/**
 * Cesium - https://github.com/CesiumGS/cesium
 *
 * Copyright 2011-2020 Cesium Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Columbus View (Pat. Pend.)
 *
 * Portions licensed separately.
 * See https://github.com/CesiumGS/cesium/blob/master/LICENSE.md for full licensing details.
 */

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
  typeof define === 'function' && define.amd ? define(['exports'], factory) :
  (global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.Cesium = {}));
}(this, (function (exports) { 'use strict';

  /**
   * @function
   *
   * @param {*} value The object.
   * @returns {Boolean} Returns true if the object is defined, returns false otherwise.
   *
   * @example
   * if (Cesium.defined(positions)) {
   *      doSomething();
   * } else {
   *      doSomethingElse();
   * }
   */
  function defined(value) {
    return value !== undefined && value !== null;
  }

  /**
   * Constructs an exception object that is thrown due to a developer error, e.g., invalid argument,
   * argument out of range, etc.  This exception should only be thrown during development;
   * it usually indicates a bug in the calling code.  This exception should never be
   * caught; instead the calling code should strive not to generate it.
   * <br /><br />
   * On the other hand, a {@link RuntimeError} indicates an exception that may
   * be thrown at runtime, e.g., out of memory, that the calling code should be prepared
   * to catch.
   *
   * @alias DeveloperError
   * @constructor
   * @extends Error
   *
   * @param {String} [message] The error message for this exception.
   *
   * @see RuntimeError
   */
  function DeveloperError(message) {
    /**
     * 'DeveloperError' indicating that this exception was thrown due to a developer error.
     * @type {String}
     * @readonly
     */
    this.name = "DeveloperError";

    /**
     * The explanation for why this exception was thrown.
     * @type {String}
     * @readonly
     */
    this.message = message;

    //Browsers such as IE don't have a stack property until you actually throw the error.
    var stack;
    try {
      throw new Error();
    } catch (e) {
      stack = e.stack;
    }

    /**
     * The stack trace of this exception, if available.
     * @type {String}
     * @readonly
     */
    this.stack = stack;
  }

  if (defined(Object.create)) {
    DeveloperError.prototype = Object.create(Error.prototype);
    DeveloperError.prototype.constructor = DeveloperError;
  }

  DeveloperError.prototype.toString = function () {
    var str = this.name + ": " + this.message;

    if (defined(this.stack)) {
      str += "\n" + this.stack.toString();
    }

    return str;
  };

  /**
   * @private
   */
  DeveloperError.throwInstantiationError = function () {
    throw new DeveloperError(
      "This function defines an interface and should not be called directly."
    );
  };

  /**
   * Contains functions for checking that supplied arguments are of a specified type
   * or meet specified conditions
   * @private
   */
  var Check = {};

  /**
   * Contains type checking functions, all using the typeof operator
   */
  Check.typeOf = {};

  function getUndefinedErrorMessage(name) {
    return name + " is required, actual value was undefined";
  }

  function getFailedTypeErrorMessage(actual, expected, name) {
    return (
      "Expected " +
      name +
      " to be typeof " +
      expected +
      ", actual typeof was " +
      actual
    );
  }

  /**
   * Throws if test is not defined
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value that is to be checked
   * @exception {DeveloperError} test must be defined
   */
  Check.defined = function (name, test) {
    if (!defined(test)) {
      throw new DeveloperError(getUndefinedErrorMessage(name));
    }
  };

  /**
   * Throws if test is not typeof 'function'
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @exception {DeveloperError} test must be typeof 'function'
   */
  Check.typeOf.func = function (name, test) {
    if (typeof test !== "function") {
      throw new DeveloperError(
        getFailedTypeErrorMessage(typeof test, "function", name)
      );
    }
  };

  /**
   * Throws if test is not typeof 'string'
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @exception {DeveloperError} test must be typeof 'string'
   */
  Check.typeOf.string = function (name, test) {
    if (typeof test !== "string") {
      throw new DeveloperError(
        getFailedTypeErrorMessage(typeof test, "string", name)
      );
    }
  };

  /**
   * Throws if test is not typeof 'number'
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @exception {DeveloperError} test must be typeof 'number'
   */
  Check.typeOf.number = function (name, test) {
    if (typeof test !== "number") {
      throw new DeveloperError(
        getFailedTypeErrorMessage(typeof test, "number", name)
      );
    }
  };

  /**
   * Throws if test is not typeof 'number' and less than limit
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @param {Number} limit The limit value to compare against
   * @exception {DeveloperError} test must be typeof 'number' and less than limit
   */
  Check.typeOf.number.lessThan = function (name, test, limit) {
    Check.typeOf.number(name, test);
    if (test >= limit) {
      throw new DeveloperError(
        "Expected " +
          name +
          " to be less than " +
          limit +
          ", actual value was " +
          test
      );
    }
  };

  /**
   * Throws if test is not typeof 'number' and less than or equal to limit
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @param {Number} limit The limit value to compare against
   * @exception {DeveloperError} test must be typeof 'number' and less than or equal to limit
   */
  Check.typeOf.number.lessThanOrEquals = function (name, test, limit) {
    Check.typeOf.number(name, test);
    if (test > limit) {
      throw new DeveloperError(
        "Expected " +
          name +
          " to be less than or equal to " +
          limit +
          ", actual value was " +
          test
      );
    }
  };

  /**
   * Throws if test is not typeof 'number' and greater than limit
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @param {Number} limit The limit value to compare against
   * @exception {DeveloperError} test must be typeof 'number' and greater than limit
   */
  Check.typeOf.number.greaterThan = function (name, test, limit) {
    Check.typeOf.number(name, test);
    if (test <= limit) {
      throw new DeveloperError(
        "Expected " +
          name +
          " to be greater than " +
          limit +
          ", actual value was " +
          test
      );
    }
  };

  /**
   * Throws if test is not typeof 'number' and greater than or equal to limit
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @param {Number} limit The limit value to compare against
   * @exception {DeveloperError} test must be typeof 'number' and greater than or equal to limit
   */
  Check.typeOf.number.greaterThanOrEquals = function (name, test, limit) {
    Check.typeOf.number(name, test);
    if (test < limit) {
      throw new DeveloperError(
        "Expected " +
          name +
          " to be greater than or equal to" +
          limit +
          ", actual value was " +
          test
      );
    }
  };

  /**
   * Throws if test is not typeof 'object'
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @exception {DeveloperError} test must be typeof 'object'
   */
  Check.typeOf.object = function (name, test) {
    if (typeof test !== "object") {
      throw new DeveloperError(
        getFailedTypeErrorMessage(typeof test, "object", name)
      );
    }
  };

  /**
   * Throws if test is not typeof 'boolean'
   *
   * @param {String} name The name of the variable being tested
   * @param {*} test The value to test
   * @exception {DeveloperError} test must be typeof 'boolean'
   */
  Check.typeOf.bool = function (name, test) {
    if (typeof test !== "boolean") {
      throw new DeveloperError(
        getFailedTypeErrorMessage(typeof test, "boolean", name)
      );
    }
  };

  /**
   * Throws if test1 and test2 is not typeof 'number' and not equal in value
   *
   * @param {String} name1 The name of the first variable being tested
   * @param {String} name2 The name of the second variable being tested against
   * @param {*} test1 The value to test
   * @param {*} test2 The value to test against
   * @exception {DeveloperError} test1 and test2 should be type of 'number' and be equal in value
   */
  Check.typeOf.number.equals = function (name1, name2, test1, test2) {
    Check.typeOf.number(name1, test1);
    Check.typeOf.number(name2, test2);
    if (test1 !== test2) {
      throw new DeveloperError(
        name1 +
          " must be equal to " +
          name2 +
          ", the actual values are " +
          test1 +
          " and " +
          test2
      );
    }
  };

  /**
   * Returns the first parameter if not undefined, otherwise the second parameter.
   * Useful for setting a default value for a parameter.
   *
   * @function
   *
   * @param {*} a
   * @param {*} b
   * @returns {*} Returns the first parameter if not undefined, otherwise the second parameter.
   *
   * @example
   * param = Cesium.defaultValue(param, 'default');
   */
  function defaultValue(a, b) {
    if (a !== undefined && a !== null) {
      return a;
    }
    return b;
  }

  /**
   * A frozen empty object that can be used as the default value for options passed as
   * an object literal.
   * @type {Object}
   * @memberof defaultValue
   */
  defaultValue.EMPTY_OBJECT = Object.freeze({});

  /*
    I've wrapped Makoto Matsumoto and Takuji Nishimura's code in a namespace
    so it's better encapsulated. Now you can have multiple random number generators
    and they won't stomp all over eachother's state.

    If you want to use this as a substitute for Math.random(), use the random()
    method like so:

    var m = new MersenneTwister();
    var randomNumber = m.random();

    You can also call the other genrand_{foo}() methods on the instance.

    If you want to use a specific seed in order to get a repeatable random
    sequence, pass an integer into the constructor:

    var m = new MersenneTwister(123);

    and that will always produce the same random sequence.

    Sean McCullough (banksean@gmail.com)
  */

  /*
     A C-program for MT19937, with initialization improved 2002/1/26.
     Coded by Takuji Nishimura and Makoto Matsumoto.

     Before using, initialize the state by using init_genrand(seed)
     or init_by_array(init_key, key_length).
  */
  /**
  @license
  mersenne-twister.js - https://gist.github.com/banksean/300494

     Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
     All rights reserved.

     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
     are met:

       1. Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

       2. Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in the
          documentation and/or other materials provided with the distribution.

       3. The names of its contributors may not be used to endorse or promote
          products derived from this software without specific prior written
          permission.

     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
  /*
     Any feedback is very welcome.
     http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
     email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
  */

  function MersenneTwister(seed) {
    if (seed == undefined) {
      seed = new Date().getTime();
    }
    /* Period parameters */
    this.N = 624;
    this.M = 397;
    this.MATRIX_A = 0x9908b0df;   /* constant vector a */
    this.UPPER_MASK = 0x80000000; /* most significant w-r bits */
    this.LOWER_MASK = 0x7fffffff; /* least significant r bits */

    this.mt = new Array(this.N); /* the array for the state vector */
    this.mti=this.N+1; /* mti==N+1 means mt[N] is not initialized */

    this.init_genrand(seed);
  }

  /* initializes mt[N] with a seed */
  MersenneTwister.prototype.init_genrand = function(s) {
    this.mt[0] = s >>> 0;
    for (this.mti=1; this.mti<this.N; this.mti++) {
        var s = this.mt[this.mti-1] ^ (this.mt[this.mti-1] >>> 30);
     this.mt[this.mti] = (((((s & 0xffff0000) >>> 16) * 1812433253) << 16) + (s & 0x0000ffff) * 1812433253)
    + this.mti;
        /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
        /* In the previous versions, MSBs of the seed affect   */
        /* only MSBs of the array mt[].                        */
        /* 2002/01/09 modified by Makoto Matsumoto             */
        this.mt[this.mti] >>>= 0;
        /* for >32 bit machines */
    }
  };

  /* initialize by an array with array-length */
  /* init_key is the array for initializing keys */
  /* key_length is its length */
  /* slight change for C++, 2004/2/26 */
  //MersenneTwister.prototype.init_by_array = function(init_key, key_length) {
  //  var i, j, k;
  //  this.init_genrand(19650218);
  //  i=1; j=0;
  //  k = (this.N>key_length ? this.N : key_length);
  //  for (; k; k--) {
  //    var s = this.mt[i-1] ^ (this.mt[i-1] >>> 30)
  //    this.mt[i] = (this.mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1664525) << 16) + ((s & 0x0000ffff) * 1664525)))
  //      + init_key[j] + j; /* non linear */
  //    this.mt[i] >>>= 0; /* for WORDSIZE > 32 machines */
  //    i++; j++;
  //    if (i>=this.N) { this.mt[0] = this.mt[this.N-1]; i=1; }
  //    if (j>=key_length) j=0;
  //  }
  //  for (k=this.N-1; k; k--) {
  //    var s = this.mt[i-1] ^ (this.mt[i-1] >>> 30);
  //    this.mt[i] = (this.mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1566083941) << 16) + (s & 0x0000ffff) * 1566083941))
  //      - i; /* non linear */
  //    this.mt[i] >>>= 0; /* for WORDSIZE > 32 machines */
  //    i++;
  //    if (i>=this.N) { this.mt[0] = this.mt[this.N-1]; i=1; }
  //  }
  //
  //  this.mt[0] = 0x80000000; /* MSB is 1; assuring non-zero initial array */
  //}

  /* generates a random number on [0,0xffffffff]-interval */
  MersenneTwister.prototype.genrand_int32 = function() {
    var y;
    var mag01 = new Array(0x0, this.MATRIX_A);
    /* mag01[x] = x * MATRIX_A  for x=0,1 */

    if (this.mti >= this.N) { /* generate N words at one time */
      var kk;

      if (this.mti == this.N+1)   /* if init_genrand() has not been called, */
        this.init_genrand(5489); /* a default initial seed is used */

      for (kk=0;kk<this.N-this.M;kk++) {
        y = (this.mt[kk]&this.UPPER_MASK)|(this.mt[kk+1]&this.LOWER_MASK);
        this.mt[kk] = this.mt[kk+this.M] ^ (y >>> 1) ^ mag01[y & 0x1];
      }
      for (;kk<this.N-1;kk++) {
        y = (this.mt[kk]&this.UPPER_MASK)|(this.mt[kk+1]&this.LOWER_MASK);
        this.mt[kk] = this.mt[kk+(this.M-this.N)] ^ (y >>> 1) ^ mag01[y & 0x1];
      }
      y = (this.mt[this.N-1]&this.UPPER_MASK)|(this.mt[0]&this.LOWER_MASK);
      this.mt[this.N-1] = this.mt[this.M-1] ^ (y >>> 1) ^ mag01[y & 0x1];

      this.mti = 0;
    }

    y = this.mt[this.mti++];

    /* Tempering */
    y ^= (y >>> 11);
    y ^= (y << 7) & 0x9d2c5680;
    y ^= (y << 15) & 0xefc60000;
    y ^= (y >>> 18);

    return y >>> 0;
  };

  /* generates a random number on [0,0x7fffffff]-interval */
  //MersenneTwister.prototype.genrand_int31 = function() {
  //  return (this.genrand_int32()>>>1);
  //}

  /* generates a random number on [0,1]-real-interval */
  //MersenneTwister.prototype.genrand_real1 = function() {
  //  return this.genrand_int32()*(1.0/4294967295.0);
  //  /* divided by 2^32-1 */
  //}

  /* generates a random number on [0,1)-real-interval */
  MersenneTwister.prototype.random = function() {
    return this.genrand_int32()*(1.0/4294967296.0);
    /* divided by 2^32 */
  };

  /**
   * Math functions.
   *
   * @exports CesiumMath
   * @alias Math
   */
  var CesiumMath = {};

  /**
   * 0.1
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON1 = 0.1;

  /**
   * 0.01
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON2 = 0.01;

  /**
   * 0.001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON3 = 0.001;

  /**
   * 0.0001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON4 = 0.0001;

  /**
   * 0.00001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON5 = 0.00001;

  /**
   * 0.000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON6 = 0.000001;

  /**
   * 0.0000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON7 = 0.0000001;

  /**
   * 0.00000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON8 = 0.00000001;

  /**
   * 0.000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON9 = 0.000000001;

  /**
   * 0.0000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON10 = 0.0000000001;

  /**
   * 0.00000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON11 = 0.00000000001;

  /**
   * 0.000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON12 = 0.000000000001;

  /**
   * 0.0000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON13 = 0.0000000000001;

  /**
   * 0.00000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON14 = 0.00000000000001;

  /**
   * 0.000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON15 = 0.000000000000001;

  /**
   * 0.0000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON16 = 0.0000000000000001;

  /**
   * 0.00000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON17 = 0.00000000000000001;

  /**
   * 0.000000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON18 = 0.000000000000000001;

  /**
   * 0.0000000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON19 = 0.0000000000000000001;

  /**
   * 0.00000000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON20 = 0.00000000000000000001;

  /**
   * 0.000000000000000000001
   * @type {Number}
   * @constant
   */
  CesiumMath.EPSILON21 = 0.000000000000000000001;

  /**
   * The gravitational parameter of the Earth in meters cubed
   * per second squared as defined by the WGS84 model: 3.986004418e14
   * @type {Number}
   * @constant
   */
  CesiumMath.GRAVITATIONALPARAMETER = 3.986004418e14;

  /**
   * Radius of the sun in meters: 6.955e8
   * @type {Number}
   * @constant
   */
  CesiumMath.SOLAR_RADIUS = 6.955e8;

  /**
   * The mean radius of the moon, according to the "Report of the IAU/IAG Working Group on
   * Cartographic Coordinates and Rotational Elements of the Planets and satellites: 2000",
   * Celestial Mechanics 82: 83-110, 2002.
   * @type {Number}
   * @constant
   */
  CesiumMath.LUNAR_RADIUS = 1737400.0;

  /**
   * 64 * 1024
   * @type {Number}
   * @constant
   */
  CesiumMath.SIXTY_FOUR_KILOBYTES = 64 * 1024;

  /**
   * 4 * 1024 * 1024 * 1024
   * @type {Number}
   * @constant
   */
  CesiumMath.FOUR_GIGABYTES = 4 * 1024 * 1024 * 1024;

  /**
   * Returns the sign of the value; 1 if the value is positive, -1 if the value is
   * negative, or 0 if the value is 0.
   *
   * @function
   * @param {Number} value The value to return the sign of.
   * @returns {Number} The sign of value.
   */
  CesiumMath.sign = defaultValue(Math.sign, function sign(value) {
    value = +value; // coerce to number
    if (value === 0 || value !== value) {
      // zero or NaN
      return value;
    }
    return value > 0 ? 1 : -1;
  });

  /**
   * Returns 1.0 if the given value is positive or zero, and -1.0 if it is negative.
   * This is similar to {@link CesiumMath#sign} except that returns 1.0 instead of
   * 0.0 when the input value is 0.0.
   * @param {Number} value The value to return the sign of.
   * @returns {Number} The sign of value.
   */
  CesiumMath.signNotZero = function (value) {
    return value < 0.0 ? -1.0 : 1.0;
  };

  /**
   * Converts a scalar value in the range [-1.0, 1.0] to a SNORM in the range [0, rangeMaximum]
   * @param {Number} value The scalar value in the range [-1.0, 1.0]
   * @param {Number} [rangeMaximum=255] The maximum value in the mapped range, 255 by default.
   * @returns {Number} A SNORM value, where 0 maps to -1.0 and rangeMaximum maps to 1.0.
   *
   * @see CesiumMath.fromSNorm
   */
  CesiumMath.toSNorm = function (value, rangeMaximum) {
    rangeMaximum = defaultValue(rangeMaximum, 255);
    return Math.round(
      (CesiumMath.clamp(value, -1.0, 1.0) * 0.5 + 0.5) * rangeMaximum
    );
  };

  /**
   * Converts a SNORM value in the range [0, rangeMaximum] to a scalar in the range [-1.0, 1.0].
   * @param {Number} value SNORM value in the range [0, rangeMaximum]
   * @param {Number} [rangeMaximum=255] The maximum value in the SNORM range, 255 by default.
   * @returns {Number} Scalar in the range [-1.0, 1.0].
   *
   * @see CesiumMath.toSNorm
   */
  CesiumMath.fromSNorm = function (value, rangeMaximum) {
    rangeMaximum = defaultValue(rangeMaximum, 255);
    return (
      (CesiumMath.clamp(value, 0.0, rangeMaximum) / rangeMaximum) * 2.0 - 1.0
    );
  };

  /**
   * Converts a scalar value in the range [rangeMinimum, rangeMaximum] to a scalar in the range [0.0, 1.0]
   * @param {Number} value The scalar value in the range [rangeMinimum, rangeMaximum]
   * @param {Number} rangeMinimum The minimum value in the mapped range.
   * @param {Number} rangeMaximum The maximum value in the mapped range.
   * @returns {Number} A scalar value, where rangeMinimum maps to 0.0 and rangeMaximum maps to 1.0.
   */
  CesiumMath.normalize = function (value, rangeMinimum, rangeMaximum) {
    rangeMaximum = Math.max(rangeMaximum - rangeMinimum, 0.0);
    return rangeMaximum === 0.0
      ? 0.0
      : CesiumMath.clamp((value - rangeMinimum) / rangeMaximum, 0.0, 1.0);
  };

  /**
   * Returns the hyperbolic sine of a number.
   * The hyperbolic sine of <em>value</em> is defined to be
   * (<em>e<sup>x</sup>&nbsp;-&nbsp;e<sup>-x</sup></em>)/2.0
   * where <i>e</i> is Euler's number, approximately 2.71828183.
   *
   * <p>Special cases:
   *   <ul>
   *     <li>If the argument is NaN, then the result is NaN.</li>
   *
   *     <li>If the argument is infinite, then the result is an infinity
   *     with the same sign as the argument.</li>
   *
   *     <li>If the argument is zero, then the result is a zero with the
   *     same sign as the argument.</li>
   *   </ul>
   *</p>
   *
   * @function
   * @param {Number} value The number whose hyperbolic sine is to be returned.
   * @returns {Number} The hyperbolic sine of <code>value</code>.
   */
  CesiumMath.sinh = defaultValue(Math.sinh, function sinh(value) {
    return (Math.exp(value) - Math.exp(-value)) / 2.0;
  });

  /**
   * Returns the hyperbolic cosine of a number.
   * The hyperbolic cosine of <strong>value</strong> is defined to be
   * (<em>e<sup>x</sup>&nbsp;+&nbsp;e<sup>-x</sup></em>)/2.0
   * where <i>e</i> is Euler's number, approximately 2.71828183.
   *
   * <p>Special cases:
   *   <ul>
   *     <li>If the argument is NaN, then the result is NaN.</li>
   *
   *     <li>If the argument is infinite, then the result is positive infinity.</li>
   *
   *     <li>If the argument is zero, then the result is 1.0.</li>
   *   </ul>
   *</p>
   *
   * @function
   * @param {Number} value The number whose hyperbolic cosine is to be returned.
   * @returns {Number} The hyperbolic cosine of <code>value</code>.
   */
  CesiumMath.cosh = defaultValue(Math.cosh, function cosh(value) {
    return (Math.exp(value) + Math.exp(-value)) / 2.0;
  });

  /**
   * Computes the linear interpolation of two values.
   *
   * @param {Number} p The start value to interpolate.
   * @param {Number} q The end value to interpolate.
   * @param {Number} time The time of interpolation generally in the range <code>[0.0, 1.0]</code>.
   * @returns {Number} The linearly interpolated value.
   *
   * @example
   * var n = Cesium.Math.lerp(0.0, 2.0, 0.5); // returns 1.0
   */
  CesiumMath.lerp = function (p, q, time) {
    return (1.0 - time) * p + time * q;
  };

  /**
   * pi
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.PI = Math.PI;

  /**
   * 1/pi
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.ONE_OVER_PI = 1.0 / Math.PI;

  /**
   * pi/2
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.PI_OVER_TWO = Math.PI / 2.0;

  /**
   * pi/3
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.PI_OVER_THREE = Math.PI / 3.0;

  /**
   * pi/4
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.PI_OVER_FOUR = Math.PI / 4.0;

  /**
   * pi/6
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.PI_OVER_SIX = Math.PI / 6.0;

  /**
   * 3pi/2
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.THREE_PI_OVER_TWO = (3.0 * Math.PI) / 2.0;

  /**
   * 2pi
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.TWO_PI = 2.0 * Math.PI;

  /**
   * 1/2pi
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.ONE_OVER_TWO_PI = 1.0 / (2.0 * Math.PI);

  /**
   * The number of radians in a degree.
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.RADIANS_PER_DEGREE = Math.PI / 180.0;

  /**
   * The number of degrees in a radian.
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.DEGREES_PER_RADIAN = 180.0 / Math.PI;

  /**
   * The number of radians in an arc second.
   *
   * @type {Number}
   * @constant
   */
  CesiumMath.RADIANS_PER_ARCSECOND = CesiumMath.RADIANS_PER_DEGREE / 3600.0;

  /**
   * Converts degrees to radians.
   * @param {Number} degrees The angle to convert in degrees.
   * @returns {Number} The corresponding angle in radians.
   */
  CesiumMath.toRadians = function (degrees) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(degrees)) {
      throw new DeveloperError("degrees is required.");
    }
    //>>includeEnd('debug');
    return degrees * CesiumMath.RADIANS_PER_DEGREE;
  };

  /**
   * Converts radians to degrees.
   * @param {Number} radians The angle to convert in radians.
   * @returns {Number} The corresponding angle in degrees.
   */
  CesiumMath.toDegrees = function (radians) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(radians)) {
      throw new DeveloperError("radians is required.");
    }
    //>>includeEnd('debug');
    return radians * CesiumMath.DEGREES_PER_RADIAN;
  };

  /**
   * Converts a longitude value, in radians, to the range [<code>-Math.PI</code>, <code>Math.PI</code>).
   *
   * @param {Number} angle The longitude value, in radians, to convert to the range [<code>-Math.PI</code>, <code>Math.PI</code>).
   * @returns {Number} The equivalent longitude value in the range [<code>-Math.PI</code>, <code>Math.PI</code>).
   *
   * @example
   * // Convert 270 degrees to -90 degrees longitude
   * var longitude = Cesium.Math.convertLongitudeRange(Cesium.Math.toRadians(270.0));
   */
  CesiumMath.convertLongitudeRange = function (angle) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(angle)) {
      throw new DeveloperError("angle is required.");
    }
    //>>includeEnd('debug');
    var twoPi = CesiumMath.TWO_PI;

    var simplified = angle - Math.floor(angle / twoPi) * twoPi;

    if (simplified < -Math.PI) {
      return simplified + twoPi;
    }
    if (simplified >= Math.PI) {
      return simplified - twoPi;
    }

    return simplified;
  };

  /**
   * Convenience function that clamps a latitude value, in radians, to the range [<code>-Math.PI/2</code>, <code>Math.PI/2</code>).
   * Useful for sanitizing data before use in objects requiring correct range.
   *
   * @param {Number} angle The latitude value, in radians, to clamp to the range [<code>-Math.PI/2</code>, <code>Math.PI/2</code>).
   * @returns {Number} The latitude value clamped to the range [<code>-Math.PI/2</code>, <code>Math.PI/2</code>).
   *
   * @example
   * // Clamp 108 degrees latitude to 90 degrees latitude
   * var latitude = Cesium.Math.clampToLatitudeRange(Cesium.Math.toRadians(108.0));
   */
  CesiumMath.clampToLatitudeRange = function (angle) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(angle)) {
      throw new DeveloperError("angle is required.");
    }
    //>>includeEnd('debug');

    return CesiumMath.clamp(
      angle,
      -1 * CesiumMath.PI_OVER_TWO,
      CesiumMath.PI_OVER_TWO
    );
  };

  /**
   * Produces an angle in the range -Pi <= angle <= Pi which is equivalent to the provided angle.
   *
   * @param {Number} angle in radians
   * @returns {Number} The angle in the range [<code>-CesiumMath.PI</code>, <code>CesiumMath.PI</code>].
   */
  CesiumMath.negativePiToPi = function (angle) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(angle)) {
      throw new DeveloperError("angle is required.");
    }
    //>>includeEnd('debug');
    return CesiumMath.zeroToTwoPi(angle + CesiumMath.PI) - CesiumMath.PI;
  };

  /**
   * Produces an angle in the range 0 <= angle <= 2Pi which is equivalent to the provided angle.
   *
   * @param {Number} angle in radians
   * @returns {Number} The angle in the range [0, <code>CesiumMath.TWO_PI</code>].
   */
  CesiumMath.zeroToTwoPi = function (angle) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(angle)) {
      throw new DeveloperError("angle is required.");
    }
    //>>includeEnd('debug');
    var mod = CesiumMath.mod(angle, CesiumMath.TWO_PI);
    if (
      Math.abs(mod) < CesiumMath.EPSILON14 &&
      Math.abs(angle) > CesiumMath.EPSILON14
    ) {
      return CesiumMath.TWO_PI;
    }
    return mod;
  };

  /**
   * The modulo operation that also works for negative dividends.
   *
   * @param {Number} m The dividend.
   * @param {Number} n The divisor.
   * @returns {Number} The remainder.
   */
  CesiumMath.mod = function (m, n) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(m)) {
      throw new DeveloperError("m is required.");
    }
    if (!defined(n)) {
      throw new DeveloperError("n is required.");
    }
    //>>includeEnd('debug');
    return ((m % n) + n) % n;
  };

  /**
   * Determines if two values are equal using an absolute or relative tolerance test. This is useful
   * to avoid problems due to roundoff error when comparing floating-point values directly. The values are
   * first compared using an absolute tolerance test. If that fails, a relative tolerance test is performed.
   * Use this test if you are unsure of the magnitudes of left and right.
   *
   * @param {Number} left The first value to compare.
   * @param {Number} right The other value to compare.
   * @param {Number} [relativeEpsilon=0] The maximum inclusive delta between <code>left</code> and <code>right</code> for the relative tolerance test.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The maximum inclusive delta between <code>left</code> and <code>right</code> for the absolute tolerance test.
   * @returns {Boolean} <code>true</code> if the values are equal within the epsilon; otherwise, <code>false</code>.
   *
   * @example
   * var a = Cesium.Math.equalsEpsilon(0.0, 0.01, Cesium.Math.EPSILON2); // true
   * var b = Cesium.Math.equalsEpsilon(0.0, 0.1, Cesium.Math.EPSILON2);  // false
   * var c = Cesium.Math.equalsEpsilon(3699175.1634344, 3699175.2, Cesium.Math.EPSILON7); // true
   * var d = Cesium.Math.equalsEpsilon(3699175.1634344, 3699175.2, Cesium.Math.EPSILON9); // false
   */
  CesiumMath.equalsEpsilon = function (
    left,
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("left is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("right is required.");
    }
    //>>includeEnd('debug');

    relativeEpsilon = defaultValue(relativeEpsilon, 0.0);
    absoluteEpsilon = defaultValue(absoluteEpsilon, relativeEpsilon);
    var absDiff = Math.abs(left - right);
    return (
      absDiff <= absoluteEpsilon ||
      absDiff <= relativeEpsilon * Math.max(Math.abs(left), Math.abs(right))
    );
  };

  /**
   * Determines if the left value is less than the right value. If the two values are within
   * <code>absoluteEpsilon</code> of each other, they are considered equal and this function returns false.
   *
   * @param {Number} left The first number to compare.
   * @param {Number} right The second number to compare.
   * @param {Number} absoluteEpsilon The absolute epsilon to use in comparison.
   * @returns {Boolean} <code>true</code> if <code>left</code> is less than <code>right</code> by more than
   *          <code>absoluteEpsilon<code>. <code>false</code> if <code>left</code> is greater or if the two
   *          values are nearly equal.
   */
  CesiumMath.lessThan = function (left, right, absoluteEpsilon) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("first is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("second is required.");
    }
    if (!defined(absoluteEpsilon)) {
      throw new DeveloperError("relativeEpsilon is required.");
    }
    //>>includeEnd('debug');
    return left - right < -absoluteEpsilon;
  };

  /**
   * Determines if the left value is less than or equal to the right value. If the two values are within
   * <code>absoluteEpsilon</code> of each other, they are considered equal and this function returns true.
   *
   * @param {Number} left The first number to compare.
   * @param {Number} right The second number to compare.
   * @param {Number} absoluteEpsilon The absolute epsilon to use in comparison.
   * @returns {Boolean} <code>true</code> if <code>left</code> is less than <code>right</code> or if the
   *          the values are nearly equal.
   */
  CesiumMath.lessThanOrEquals = function (left, right, absoluteEpsilon) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("first is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("second is required.");
    }
    if (!defined(absoluteEpsilon)) {
      throw new DeveloperError("relativeEpsilon is required.");
    }
    //>>includeEnd('debug');
    return left - right < absoluteEpsilon;
  };

  /**
   * Determines if the left value is greater the right value. If the two values are within
   * <code>absoluteEpsilon</code> of each other, they are considered equal and this function returns false.
   *
   * @param {Number} left The first number to compare.
   * @param {Number} right The second number to compare.
   * @param {Number} absoluteEpsilon The absolute epsilon to use in comparison.
   * @returns {Boolean} <code>true</code> if <code>left</code> is greater than <code>right</code> by more than
   *          <code>absoluteEpsilon<code>. <code>false</code> if <code>left</code> is less or if the two
   *          values are nearly equal.
   */
  CesiumMath.greaterThan = function (left, right, absoluteEpsilon) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("first is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("second is required.");
    }
    if (!defined(absoluteEpsilon)) {
      throw new DeveloperError("relativeEpsilon is required.");
    }
    //>>includeEnd('debug');
    return left - right > absoluteEpsilon;
  };

  /**
   * Determines if the left value is greater than or equal to the right value. If the two values are within
   * <code>absoluteEpsilon</code> of each other, they are considered equal and this function returns true.
   *
   * @param {Number} left The first number to compare.
   * @param {Number} right The second number to compare.
   * @param {Number} absoluteEpsilon The absolute epsilon to use in comparison.
   * @returns {Boolean} <code>true</code> if <code>left</code> is greater than <code>right</code> or if the
   *          the values are nearly equal.
   */
  CesiumMath.greaterThanOrEquals = function (left, right, absoluteEpsilon) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("first is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("second is required.");
    }
    if (!defined(absoluteEpsilon)) {
      throw new DeveloperError("relativeEpsilon is required.");
    }
    //>>includeEnd('debug');
    return left - right > -absoluteEpsilon;
  };

  var factorials = [1];

  /**
   * Computes the factorial of the provided number.
   *
   * @param {Number} n The number whose factorial is to be computed.
   * @returns {Number} The factorial of the provided number or undefined if the number is less than 0.
   *
   * @exception {DeveloperError} A number greater than or equal to 0 is required.
   *
   *
   * @example
   * //Compute 7!, which is equal to 5040
   * var computedFactorial = Cesium.Math.factorial(7);
   *
   * @see {@link http://en.wikipedia.org/wiki/Factorial|Factorial on Wikipedia}
   */
  CesiumMath.factorial = function (n) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof n !== "number" || n < 0) {
      throw new DeveloperError(
        "A number greater than or equal to 0 is required."
      );
    }
    //>>includeEnd('debug');

    var length = factorials.length;
    if (n >= length) {
      var sum = factorials[length - 1];
      for (var i = length; i <= n; i++) {
        var next = sum * i;
        factorials.push(next);
        sum = next;
      }
    }
    return factorials[n];
  };

  /**
   * Increments a number with a wrapping to a minimum value if the number exceeds the maximum value.
   *
   * @param {Number} [n] The number to be incremented.
   * @param {Number} [maximumValue] The maximum incremented value before rolling over to the minimum value.
   * @param {Number} [minimumValue=0.0] The number reset to after the maximum value has been exceeded.
   * @returns {Number} The incremented number.
   *
   * @exception {DeveloperError} Maximum value must be greater than minimum value.
   *
   * @example
   * var n = Cesium.Math.incrementWrap(5, 10, 0); // returns 6
   * var n = Cesium.Math.incrementWrap(10, 10, 0); // returns 0
   */
  CesiumMath.incrementWrap = function (n, maximumValue, minimumValue) {
    minimumValue = defaultValue(minimumValue, 0.0);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(n)) {
      throw new DeveloperError("n is required.");
    }
    if (maximumValue <= minimumValue) {
      throw new DeveloperError("maximumValue must be greater than minimumValue.");
    }
    //>>includeEnd('debug');

    ++n;
    if (n > maximumValue) {
      n = minimumValue;
    }
    return n;
  };

  /**
   * Determines if a positive integer is a power of two.
   *
   * @param {Number} n The positive integer to test.
   * @returns {Boolean} <code>true</code> if the number if a power of two; otherwise, <code>false</code>.
   *
   * @exception {DeveloperError} A number greater than or equal to 0 is required.
   *
   * @example
   * var t = Cesium.Math.isPowerOfTwo(16); // true
   * var f = Cesium.Math.isPowerOfTwo(20); // false
   */
  CesiumMath.isPowerOfTwo = function (n) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof n !== "number" || n < 0) {
      throw new DeveloperError(
        "A number greater than or equal to 0 is required."
      );
    }
    //>>includeEnd('debug');

    return n !== 0 && (n & (n - 1)) === 0;
  };

  /**
   * Computes the next power-of-two integer greater than or equal to the provided positive integer.
   *
   * @param {Number} n The positive integer to test.
   * @returns {Number} The next power-of-two integer.
   *
   * @exception {DeveloperError} A number greater than or equal to 0 is required.
   *
   * @example
   * var n = Cesium.Math.nextPowerOfTwo(29); // 32
   * var m = Cesium.Math.nextPowerOfTwo(32); // 32
   */
  CesiumMath.nextPowerOfTwo = function (n) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof n !== "number" || n < 0) {
      throw new DeveloperError(
        "A number greater than or equal to 0 is required."
      );
    }
    //>>includeEnd('debug');

    // From http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
    --n;
    n |= n >> 1;
    n |= n >> 2;
    n |= n >> 4;
    n |= n >> 8;
    n |= n >> 16;
    ++n;

    return n;
  };

  /**
   * Constraint a value to lie between two values.
   *
   * @param {Number} value The value to constrain.
   * @param {Number} min The minimum value.
   * @param {Number} max The maximum value.
   * @returns {Number} The value clamped so that min <= value <= max.
   */
  CesiumMath.clamp = function (value, min, max) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(min)) {
      throw new DeveloperError("min is required.");
    }
    if (!defined(max)) {
      throw new DeveloperError("max is required.");
    }
    //>>includeEnd('debug');
    return value < min ? min : value > max ? max : value;
  };

  var randomNumberGenerator = new MersenneTwister();

  /**
   * Sets the seed used by the random number generator
   * in {@link CesiumMath#nextRandomNumber}.
   *
   * @param {Number} seed An integer used as the seed.
   */
  CesiumMath.setRandomNumberSeed = function (seed) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(seed)) {
      throw new DeveloperError("seed is required.");
    }
    //>>includeEnd('debug');

    randomNumberGenerator = new MersenneTwister(seed);
  };

  /**
   * Generates a random floating point number in the range of [0.0, 1.0)
   * using a Mersenne twister.
   *
   * @returns {Number} A random number in the range of [0.0, 1.0).
   *
   * @see CesiumMath.setRandomNumberSeed
   * @see {@link http://en.wikipedia.org/wiki/Mersenne_twister|Mersenne twister on Wikipedia}
   */
  CesiumMath.nextRandomNumber = function () {
    return randomNumberGenerator.random();
  };

  /**
   * Generates a random number between two numbers.
   *
   * @param {Number} min The minimum value.
   * @param {Number} max The maximum value.
   * @returns {Number} A random number between the min and max.
   */
  CesiumMath.randomBetween = function (min, max) {
    return CesiumMath.nextRandomNumber() * (max - min) + min;
  };

  /**
   * Computes <code>Math.acos(value)</code>, but first clamps <code>value</code> to the range [-1.0, 1.0]
   * so that the function will never return NaN.
   *
   * @param {Number} value The value for which to compute acos.
   * @returns {Number} The acos of the value if the value is in the range [-1.0, 1.0], or the acos of -1.0 or 1.0,
   *          whichever is closer, if the value is outside the range.
   */
  CesiumMath.acosClamped = function (value) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required.");
    }
    //>>includeEnd('debug');
    return Math.acos(CesiumMath.clamp(value, -1.0, 1.0));
  };

  /**
   * Computes <code>Math.asin(value)</code>, but first clamps <code>value</code> to the range [-1.0, 1.0]
   * so that the function will never return NaN.
   *
   * @param {Number} value The value for which to compute asin.
   * @returns {Number} The asin of the value if the value is in the range [-1.0, 1.0], or the asin of -1.0 or 1.0,
   *          whichever is closer, if the value is outside the range.
   */
  CesiumMath.asinClamped = function (value) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required.");
    }
    //>>includeEnd('debug');
    return Math.asin(CesiumMath.clamp(value, -1.0, 1.0));
  };

  /**
   * Finds the chord length between two points given the circle's radius and the angle between the points.
   *
   * @param {Number} angle The angle between the two points.
   * @param {Number} radius The radius of the circle.
   * @returns {Number} The chord length.
   */
  CesiumMath.chordLength = function (angle, radius) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(angle)) {
      throw new DeveloperError("angle is required.");
    }
    if (!defined(radius)) {
      throw new DeveloperError("radius is required.");
    }
    //>>includeEnd('debug');
    return 2.0 * radius * Math.sin(angle * 0.5);
  };

  /**
   * Finds the logarithm of a number to a base.
   *
   * @param {Number} number The number.
   * @param {Number} base The base.
   * @returns {Number} The result.
   */
  CesiumMath.logBase = function (number, base) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(number)) {
      throw new DeveloperError("number is required.");
    }
    if (!defined(base)) {
      throw new DeveloperError("base is required.");
    }
    //>>includeEnd('debug');
    return Math.log(number) / Math.log(base);
  };

  /**
   * Finds the cube root of a number.
   * Returns NaN if <code>number</code> is not provided.
   *
   * @function
   * @param {Number} [number] The number.
   * @returns {Number} The result.
   */
  CesiumMath.cbrt = defaultValue(Math.cbrt, function cbrt(number) {
    var result = Math.pow(Math.abs(number), 1.0 / 3.0);
    return number < 0.0 ? -result : result;
  });

  /**
   * Finds the base 2 logarithm of a number.
   *
   * @function
   * @param {Number} number The number.
   * @returns {Number} The result.
   */
  CesiumMath.log2 = defaultValue(Math.log2, function log2(number) {
    return Math.log(number) * Math.LOG2E;
  });

  /**
   * @private
   */
  CesiumMath.fog = function (distanceToCamera, density) {
    var scalar = distanceToCamera * density;
    return 1.0 - Math.exp(-(scalar * scalar));
  };

  /**
   * Computes a fast approximation of Atan for input in the range [-1, 1].
   *
   * Based on Michal Drobot's approximation from ShaderFastLibs,
   * which in turn is based on "Efficient approximations for the arctangent function,"
   * Rajan, S. Sichun Wang Inkol, R. Joyal, A., May 2006.
   * Adapted from ShaderFastLibs under MIT License.
   *
   * @param {Number} x An input number in the range [-1, 1]
   * @returns {Number} An approximation of atan(x)
   */
  CesiumMath.fastApproximateAtan = function (x) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("x", x);
    //>>includeEnd('debug');

    return x * (-0.1784 * Math.abs(x) - 0.0663 * x * x + 1.0301);
  };

  /**
   * Computes a fast approximation of Atan2(x, y) for arbitrary input scalars.
   *
   * Range reduction math based on nvidia's cg reference implementation: http://developer.download.nvidia.com/cg/atan2.html
   *
   * @param {Number} x An input number that isn't zero if y is zero.
   * @param {Number} y An input number that isn't zero if x is zero.
   * @returns {Number} An approximation of atan2(x, y)
   */
  CesiumMath.fastApproximateAtan2 = function (x, y) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("x", x);
    Check.typeOf.number("y", y);
    //>>includeEnd('debug');

    // atan approximations are usually only reliable over [-1, 1]
    // So reduce the range by flipping whether x or y is on top based on which is bigger.
    var opposite;
    var adjacent;
    var t = Math.abs(x); // t used as swap and atan result.
    opposite = Math.abs(y);
    adjacent = Math.max(t, opposite);
    opposite = Math.min(t, opposite);

    var oppositeOverAdjacent = opposite / adjacent;
    //>>includeStart('debug', pragmas.debug);
    if (isNaN(oppositeOverAdjacent)) {
      throw new DeveloperError("either x or y must be nonzero");
    }
    //>>includeEnd('debug');
    t = CesiumMath.fastApproximateAtan(oppositeOverAdjacent);

    // Undo range reduction
    t = Math.abs(y) > Math.abs(x) ? CesiumMath.PI_OVER_TWO - t : t;
    t = x < 0.0 ? CesiumMath.PI - t : t;
    t = y < 0.0 ? -t : t;
    return t;
  };

  /**
   * A 3D Cartesian point.
   * @alias Cartesian3
   * @constructor
   *
   * @param {Number} [x=0.0] The X component.
   * @param {Number} [y=0.0] The Y component.
   * @param {Number} [z=0.0] The Z component.
   *
   * @see Cartesian2
   * @see Cartesian4
   * @see Packable
   */
  function Cartesian3(x, y, z) {
    /**
     * The X component.
     * @type {Number}
     * @default 0.0
     */
    this.x = defaultValue(x, 0.0);

    /**
     * The Y component.
     * @type {Number}
     * @default 0.0
     */
    this.y = defaultValue(y, 0.0);

    /**
     * The Z component.
     * @type {Number}
     * @default 0.0
     */
    this.z = defaultValue(z, 0.0);
  }

  /**
   * Converts the provided Spherical into Cartesian3 coordinates.
   *
   * @param {Spherical} spherical The Spherical to be converted to Cartesian3.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   */
  Cartesian3.fromSpherical = function (spherical, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("spherical", spherical);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    var clock = spherical.clock;
    var cone = spherical.cone;
    var magnitude = defaultValue(spherical.magnitude, 1.0);
    var radial = magnitude * Math.sin(cone);
    result.x = radial * Math.cos(clock);
    result.y = radial * Math.sin(clock);
    result.z = magnitude * Math.cos(cone);
    return result;
  };

  /**
   * Creates a Cartesian3 instance from x, y and z coordinates.
   *
   * @param {Number} x The x coordinate.
   * @param {Number} y The y coordinate.
   * @param {Number} z The z coordinate.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   */
  Cartesian3.fromElements = function (x, y, z, result) {
    if (!defined(result)) {
      return new Cartesian3(x, y, z);
    }

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Duplicates a Cartesian3 instance.
   *
   * @param {Cartesian3} cartesian The Cartesian to duplicate.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided. (Returns undefined if cartesian is undefined)
   */
  Cartesian3.clone = function (cartesian, result) {
    if (!defined(cartesian)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Cartesian3(cartesian.x, cartesian.y, cartesian.z);
    }

    result.x = cartesian.x;
    result.y = cartesian.y;
    result.z = cartesian.z;
    return result;
  };

  /**
   * Creates a Cartesian3 instance from an existing Cartesian4.  This simply takes the
   * x, y, and z properties of the Cartesian4 and drops w.
   * @function
   *
   * @param {Cartesian4} cartesian The Cartesian4 instance to create a Cartesian3 instance from.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   */
  Cartesian3.fromCartesian4 = Cartesian3.clone;

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Cartesian3.packedLength = 3;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Cartesian3} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Cartesian3.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.x;
    array[startingIndex++] = value.y;
    array[startingIndex] = value.z;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Cartesian3} [result] The object into which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   */
  Cartesian3.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Cartesian3();
    }
    result.x = array[startingIndex++];
    result.y = array[startingIndex++];
    result.z = array[startingIndex];
    return result;
  };

  /**
   * Flattens an array of Cartesian3s into an array of components.
   *
   * @param {Cartesian3[]} array The array of cartesians to pack.
   * @param {Number[]} [result] The array onto which to store the result. If this is a typed array, it must have array.length * 3 components, else a {@link DeveloperError} will be thrown. If it is a regular array, it will be resized to have (array.length * 3) elements.
   * @returns {Number[]} The packed array.
   */
  Cartesian3.packArray = function (array, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    var length = array.length;
    var resultLength = length * 3;
    if (!defined(result)) {
      result = new Array(resultLength);
    } else if (!Array.isArray(result) && result.length !== resultLength) {
      throw new DeveloperError(
        "If result is a typed array, it must have exactly array.length * 3 elements"
      );
    } else if (result.length !== resultLength) {
      result.length = resultLength;
    }

    for (var i = 0; i < length; ++i) {
      Cartesian3.pack(array[i], result, i * 3);
    }
    return result;
  };

  /**
   * Unpacks an array of cartesian components into an array of Cartesian3s.
   *
   * @param {Number[]} array The array of components to unpack.
   * @param {Cartesian3[]} [result] The array onto which to store the result.
   * @returns {Cartesian3[]} The unpacked array.
   */
  Cartesian3.unpackArray = function (array, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    Check.typeOf.number.greaterThanOrEquals("array.length", array.length, 3);
    if (array.length % 3 !== 0) {
      throw new DeveloperError("array length must be a multiple of 3.");
    }
    //>>includeEnd('debug');

    var length = array.length;
    if (!defined(result)) {
      result = new Array(length / 3);
    } else {
      result.length = length / 3;
    }

    for (var i = 0; i < length; i += 3) {
      var index = i / 3;
      result[index] = Cartesian3.unpack(array, i, result[index]);
    }
    return result;
  };

  /**
   * Creates a Cartesian3 from three consecutive elements in an array.
   * @function
   *
   * @param {Number[]} array The array whose three consecutive elements correspond to the x, y, and z components, respectively.
   * @param {Number} [startingIndex=0] The offset into the array of the first element, which corresponds to the x component.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   *
   * @example
   * // Create a Cartesian3 with (1.0, 2.0, 3.0)
   * var v = [1.0, 2.0, 3.0];
   * var p = Cesium.Cartesian3.fromArray(v);
   *
   * // Create a Cartesian3 with (1.0, 2.0, 3.0) using an offset into an array
   * var v2 = [0.0, 0.0, 1.0, 2.0, 3.0];
   * var p2 = Cesium.Cartesian3.fromArray(v2, 2);
   */
  Cartesian3.fromArray = Cartesian3.unpack;

  /**
   * Computes the value of the maximum component for the supplied Cartesian.
   *
   * @param {Cartesian3} cartesian The cartesian to use.
   * @returns {Number} The value of the maximum component.
   */
  Cartesian3.maximumComponent = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return Math.max(cartesian.x, cartesian.y, cartesian.z);
  };

  /**
   * Computes the value of the minimum component for the supplied Cartesian.
   *
   * @param {Cartesian3} cartesian The cartesian to use.
   * @returns {Number} The value of the minimum component.
   */
  Cartesian3.minimumComponent = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return Math.min(cartesian.x, cartesian.y, cartesian.z);
  };

  /**
   * Compares two Cartesians and computes a Cartesian which contains the minimum components of the supplied Cartesians.
   *
   * @param {Cartesian3} first A cartesian to compare.
   * @param {Cartesian3} second A cartesian to compare.
   * @param {Cartesian3} result The object into which to store the result.
   * @returns {Cartesian3} A cartesian with the minimum components.
   */
  Cartesian3.minimumByComponent = function (first, second, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("first", first);
    Check.typeOf.object("second", second);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.min(first.x, second.x);
    result.y = Math.min(first.y, second.y);
    result.z = Math.min(first.z, second.z);

    return result;
  };

  /**
   * Compares two Cartesians and computes a Cartesian which contains the maximum components of the supplied Cartesians.
   *
   * @param {Cartesian3} first A cartesian to compare.
   * @param {Cartesian3} second A cartesian to compare.
   * @param {Cartesian3} result The object into which to store the result.
   * @returns {Cartesian3} A cartesian with the maximum components.
   */
  Cartesian3.maximumByComponent = function (first, second, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("first", first);
    Check.typeOf.object("second", second);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.max(first.x, second.x);
    result.y = Math.max(first.y, second.y);
    result.z = Math.max(first.z, second.z);
    return result;
  };

  /**
   * Computes the provided Cartesian's squared magnitude.
   *
   * @param {Cartesian3} cartesian The Cartesian instance whose squared magnitude is to be computed.
   * @returns {Number} The squared magnitude.
   */
  Cartesian3.magnitudeSquared = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return (
      cartesian.x * cartesian.x +
      cartesian.y * cartesian.y +
      cartesian.z * cartesian.z
    );
  };

  /**
   * Computes the Cartesian's magnitude (length).
   *
   * @param {Cartesian3} cartesian The Cartesian instance whose magnitude is to be computed.
   * @returns {Number} The magnitude.
   */
  Cartesian3.magnitude = function (cartesian) {
    return Math.sqrt(Cartesian3.magnitudeSquared(cartesian));
  };

  var distanceScratch = new Cartesian3();

  /**
   * Computes the distance between two points.
   *
   * @param {Cartesian3} left The first point to compute the distance from.
   * @param {Cartesian3} right The second point to compute the distance to.
   * @returns {Number} The distance between two points.
   *
   * @example
   * // Returns 1.0
   * var d = Cesium.Cartesian3.distance(new Cesium.Cartesian3(1.0, 0.0, 0.0), new Cesium.Cartesian3(2.0, 0.0, 0.0));
   */
  Cartesian3.distance = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian3.subtract(left, right, distanceScratch);
    return Cartesian3.magnitude(distanceScratch);
  };

  /**
   * Computes the squared distance between two points.  Comparing squared distances
   * using this function is more efficient than comparing distances using {@link Cartesian3#distance}.
   *
   * @param {Cartesian3} left The first point to compute the distance from.
   * @param {Cartesian3} right The second point to compute the distance to.
   * @returns {Number} The distance between two points.
   *
   * @example
   * // Returns 4.0, not 2.0
   * var d = Cesium.Cartesian3.distanceSquared(new Cesium.Cartesian3(1.0, 0.0, 0.0), new Cesium.Cartesian3(3.0, 0.0, 0.0));
   */
  Cartesian3.distanceSquared = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian3.subtract(left, right, distanceScratch);
    return Cartesian3.magnitudeSquared(distanceScratch);
  };

  /**
   * Computes the normalized form of the supplied Cartesian.
   *
   * @param {Cartesian3} cartesian The Cartesian to be normalized.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.normalize = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var magnitude = Cartesian3.magnitude(cartesian);

    result.x = cartesian.x / magnitude;
    result.y = cartesian.y / magnitude;
    result.z = cartesian.z / magnitude;

    //>>includeStart('debug', pragmas.debug);
    if (isNaN(result.x) || isNaN(result.y) || isNaN(result.z)) {
      throw new DeveloperError("normalized result is not a number");
    }
    //>>includeEnd('debug');

    return result;
  };

  /**
   * Computes the dot (scalar) product of two Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @returns {Number} The dot product.
   */
  Cartesian3.dot = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    return left.x * right.x + left.y * right.y + left.z * right.z;
  };

  /**
   * Computes the componentwise product of two Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.multiplyComponents = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x * right.x;
    result.y = left.y * right.y;
    result.z = left.z * right.z;
    return result;
  };

  /**
   * Computes the componentwise quotient of two Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.divideComponents = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x / right.x;
    result.y = left.y / right.y;
    result.z = left.z / right.z;
    return result;
  };

  /**
   * Computes the componentwise sum of two Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x + right.x;
    result.y = left.y + right.y;
    result.z = left.z + right.z;
    return result;
  };

  /**
   * Computes the componentwise difference of two Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x - right.x;
    result.y = left.y - right.y;
    result.z = left.z - right.z;
    return result;
  };

  /**
   * Multiplies the provided Cartesian componentwise by the provided scalar.
   *
   * @param {Cartesian3} cartesian The Cartesian to be scaled.
   * @param {Number} scalar The scalar to multiply with.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.multiplyByScalar = function (cartesian, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = cartesian.x * scalar;
    result.y = cartesian.y * scalar;
    result.z = cartesian.z * scalar;
    return result;
  };

  /**
   * Divides the provided Cartesian componentwise by the provided scalar.
   *
   * @param {Cartesian3} cartesian The Cartesian to be divided.
   * @param {Number} scalar The scalar to divide by.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.divideByScalar = function (cartesian, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = cartesian.x / scalar;
    result.y = cartesian.y / scalar;
    result.z = cartesian.z / scalar;
    return result;
  };

  /**
   * Negates the provided Cartesian.
   *
   * @param {Cartesian3} cartesian The Cartesian to be negated.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.negate = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = -cartesian.x;
    result.y = -cartesian.y;
    result.z = -cartesian.z;
    return result;
  };

  /**
   * Computes the absolute value of the provided Cartesian.
   *
   * @param {Cartesian3} cartesian The Cartesian whose absolute value is to be computed.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.abs = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.abs(cartesian.x);
    result.y = Math.abs(cartesian.y);
    result.z = Math.abs(cartesian.z);
    return result;
  };

  var lerpScratch = new Cartesian3();
  /**
   * Computes the linear interpolation or extrapolation at t using the provided cartesians.
   *
   * @param {Cartesian3} start The value corresponding to t at 0.0.
   * @param {Cartesian3} end The value corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Cartesian3.lerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    Cartesian3.multiplyByScalar(end, t, lerpScratch);
    result = Cartesian3.multiplyByScalar(start, 1.0 - t, result);
    return Cartesian3.add(lerpScratch, result, result);
  };

  var angleBetweenScratch = new Cartesian3();
  var angleBetweenScratch2 = new Cartesian3();
  /**
   * Returns the angle, in radians, between the provided Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @returns {Number} The angle between the Cartesians.
   */
  Cartesian3.angleBetween = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian3.normalize(left, angleBetweenScratch);
    Cartesian3.normalize(right, angleBetweenScratch2);
    var cosine = Cartesian3.dot(angleBetweenScratch, angleBetweenScratch2);
    var sine = Cartesian3.magnitude(
      Cartesian3.cross(
        angleBetweenScratch,
        angleBetweenScratch2,
        angleBetweenScratch
      )
    );
    return Math.atan2(sine, cosine);
  };

  var mostOrthogonalAxisScratch = new Cartesian3();
  /**
   * Returns the axis that is most orthogonal to the provided Cartesian.
   *
   * @param {Cartesian3} cartesian The Cartesian on which to find the most orthogonal axis.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The most orthogonal axis.
   */
  Cartesian3.mostOrthogonalAxis = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var f = Cartesian3.normalize(cartesian, mostOrthogonalAxisScratch);
    Cartesian3.abs(f, f);

    if (f.x <= f.y) {
      if (f.x <= f.z) {
        result = Cartesian3.clone(Cartesian3.UNIT_X, result);
      } else {
        result = Cartesian3.clone(Cartesian3.UNIT_Z, result);
      }
    } else if (f.y <= f.z) {
      result = Cartesian3.clone(Cartesian3.UNIT_Y, result);
    } else {
      result = Cartesian3.clone(Cartesian3.UNIT_Z, result);
    }

    return result;
  };

  /**
   * Projects vector a onto vector b
   * @param {Cartesian3} a The vector that needs projecting
   * @param {Cartesian3} b The vector to project onto
   * @param {Cartesian3} result The result cartesian
   * @returns {Cartesian3} The modified result parameter
   */
  Cartesian3.projectVector = function (a, b, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("a", a);
    Check.defined("b", b);
    Check.defined("result", result);
    //>>includeEnd('debug');

    var scalar = Cartesian3.dot(a, b) / Cartesian3.dot(b, b);
    return Cartesian3.multiplyByScalar(b, scalar, result);
  };

  /**
   * Compares the provided Cartesians componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartesian3} [left] The first Cartesian.
   * @param {Cartesian3} [right] The second Cartesian.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Cartesian3.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.x === right.x &&
        left.y === right.y &&
        left.z === right.z)
    );
  };

  /**
   * @private
   */
  Cartesian3.equalsArray = function (cartesian, array, offset) {
    return (
      cartesian.x === array[offset] &&
      cartesian.y === array[offset + 1] &&
      cartesian.z === array[offset + 2]
    );
  };

  /**
   * Compares the provided Cartesians componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Cartesian3} [left] The first Cartesian.
   * @param {Cartesian3} [right] The second Cartesian.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartesian3.equalsEpsilon = function (
    left,
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        CesiumMath.equalsEpsilon(
          left.x,
          right.x,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.y,
          right.y,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.z,
          right.z,
          relativeEpsilon,
          absoluteEpsilon
        ))
    );
  };

  /**
   * Computes the cross (outer) product of two Cartesians.
   *
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The cross product.
   */
  Cartesian3.cross = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var leftX = left.x;
    var leftY = left.y;
    var leftZ = left.z;
    var rightX = right.x;
    var rightY = right.y;
    var rightZ = right.z;

    var x = leftY * rightZ - leftZ * rightY;
    var y = leftZ * rightX - leftX * rightZ;
    var z = leftX * rightY - leftY * rightX;

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Computes the midpoint between the right and left Cartesian.
   * @param {Cartesian3} left The first Cartesian.
   * @param {Cartesian3} right The second Cartesian.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The midpoint.
   */
  Cartesian3.midpoint = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = (left.x + right.x) * 0.5;
    result.y = (left.y + right.y) * 0.5;
    result.z = (left.z + right.z) * 0.5;

    return result;
  };

  /**
   * Returns a Cartesian3 position from longitude and latitude values given in degrees.
   *
   * @param {Number} longitude The longitude, in degrees
   * @param {Number} latitude The latitude, in degrees
   * @param {Number} [height=0.0] The height, in meters, above the ellipsoid.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The position
   *
   * @example
   * var position = Cesium.Cartesian3.fromDegrees(-115.0, 37.0);
   */
  Cartesian3.fromDegrees = function (
    longitude,
    latitude,
    height,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("longitude", longitude);
    Check.typeOf.number("latitude", latitude);
    //>>includeEnd('debug');

    longitude = CesiumMath.toRadians(longitude);
    latitude = CesiumMath.toRadians(latitude);
    return Cartesian3.fromRadians(longitude, latitude, height, ellipsoid, result);
  };

  var scratchN = new Cartesian3();
  var scratchK = new Cartesian3();
  var wgs84RadiiSquared = new Cartesian3(
    6378137.0 * 6378137.0,
    6378137.0 * 6378137.0,
    6356752.3142451793 * 6356752.3142451793
  );

  /**
   * Returns a Cartesian3 position from longitude and latitude values given in radians.
   *
   * @param {Number} longitude The longitude, in radians
   * @param {Number} latitude The latitude, in radians
   * @param {Number} [height=0.0] The height, in meters, above the ellipsoid.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The position
   *
   * @example
   * var position = Cesium.Cartesian3.fromRadians(-2.007, 0.645);
   */
  Cartesian3.fromRadians = function (
    longitude,
    latitude,
    height,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("longitude", longitude);
    Check.typeOf.number("latitude", latitude);
    //>>includeEnd('debug');

    height = defaultValue(height, 0.0);
    var radiiSquared = defined(ellipsoid)
      ? ellipsoid.radiiSquared
      : wgs84RadiiSquared;

    var cosLatitude = Math.cos(latitude);
    scratchN.x = cosLatitude * Math.cos(longitude);
    scratchN.y = cosLatitude * Math.sin(longitude);
    scratchN.z = Math.sin(latitude);
    scratchN = Cartesian3.normalize(scratchN, scratchN);

    Cartesian3.multiplyComponents(radiiSquared, scratchN, scratchK);
    var gamma = Math.sqrt(Cartesian3.dot(scratchN, scratchK));
    scratchK = Cartesian3.divideByScalar(scratchK, gamma, scratchK);
    scratchN = Cartesian3.multiplyByScalar(scratchN, height, scratchN);

    if (!defined(result)) {
      result = new Cartesian3();
    }
    return Cartesian3.add(scratchK, scratchN, result);
  };

  /**
   * Returns an array of Cartesian3 positions given an array of longitude and latitude values given in degrees.
   *
   * @param {Number[]} coordinates A list of longitude and latitude values. Values alternate [longitude, latitude, longitude, latitude...].
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the coordinates lie.
   * @param {Cartesian3[]} [result] An array of Cartesian3 objects to store the result.
   * @returns {Cartesian3[]} The array of positions.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArray([-115.0, 37.0, -107.0, 33.0]);
   */
  Cartesian3.fromDegreesArray = function (coordinates, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("coordinates", coordinates);
    if (coordinates.length < 2 || coordinates.length % 2 !== 0) {
      throw new DeveloperError(
        "the number of coordinates must be a multiple of 2 and at least 2"
      );
    }
    //>>includeEnd('debug');

    var length = coordinates.length;
    if (!defined(result)) {
      result = new Array(length / 2);
    } else {
      result.length = length / 2;
    }

    for (var i = 0; i < length; i += 2) {
      var longitude = coordinates[i];
      var latitude = coordinates[i + 1];
      var index = i / 2;
      result[index] = Cartesian3.fromDegrees(
        longitude,
        latitude,
        0,
        ellipsoid,
        result[index]
      );
    }

    return result;
  };

  /**
   * Returns an array of Cartesian3 positions given an array of longitude and latitude values given in radians.
   *
   * @param {Number[]} coordinates A list of longitude and latitude values. Values alternate [longitude, latitude, longitude, latitude...].
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the coordinates lie.
   * @param {Cartesian3[]} [result] An array of Cartesian3 objects to store the result.
   * @returns {Cartesian3[]} The array of positions.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromRadiansArray([-2.007, 0.645, -1.867, .575]);
   */
  Cartesian3.fromRadiansArray = function (coordinates, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("coordinates", coordinates);
    if (coordinates.length < 2 || coordinates.length % 2 !== 0) {
      throw new DeveloperError(
        "the number of coordinates must be a multiple of 2 and at least 2"
      );
    }
    //>>includeEnd('debug');

    var length = coordinates.length;
    if (!defined(result)) {
      result = new Array(length / 2);
    } else {
      result.length = length / 2;
    }

    for (var i = 0; i < length; i += 2) {
      var longitude = coordinates[i];
      var latitude = coordinates[i + 1];
      var index = i / 2;
      result[index] = Cartesian3.fromRadians(
        longitude,
        latitude,
        0,
        ellipsoid,
        result[index]
      );
    }

    return result;
  };

  /**
   * Returns an array of Cartesian3 positions given an array of longitude, latitude and height values where longitude and latitude are given in degrees.
   *
   * @param {Number[]} coordinates A list of longitude, latitude and height values. Values alternate [longitude, latitude, height, longitude, latitude, height...].
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
   * @param {Cartesian3[]} [result] An array of Cartesian3 objects to store the result.
   * @returns {Cartesian3[]} The array of positions.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArrayHeights([-115.0, 37.0, 100000.0, -107.0, 33.0, 150000.0]);
   */
  Cartesian3.fromDegreesArrayHeights = function (coordinates, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("coordinates", coordinates);
    if (coordinates.length < 3 || coordinates.length % 3 !== 0) {
      throw new DeveloperError(
        "the number of coordinates must be a multiple of 3 and at least 3"
      );
    }
    //>>includeEnd('debug');

    var length = coordinates.length;
    if (!defined(result)) {
      result = new Array(length / 3);
    } else {
      result.length = length / 3;
    }

    for (var i = 0; i < length; i += 3) {
      var longitude = coordinates[i];
      var latitude = coordinates[i + 1];
      var height = coordinates[i + 2];
      var index = i / 3;
      result[index] = Cartesian3.fromDegrees(
        longitude,
        latitude,
        height,
        ellipsoid,
        result[index]
      );
    }

    return result;
  };

  /**
   * Returns an array of Cartesian3 positions given an array of longitude, latitude and height values where longitude and latitude are given in radians.
   *
   * @param {Number[]} coordinates A list of longitude, latitude and height values. Values alternate [longitude, latitude, height, longitude, latitude, height...].
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
   * @param {Cartesian3[]} [result] An array of Cartesian3 objects to store the result.
   * @returns {Cartesian3[]} The array of positions.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromRadiansArrayHeights([-2.007, 0.645, 100000.0, -1.867, .575, 150000.0]);
   */
  Cartesian3.fromRadiansArrayHeights = function (coordinates, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("coordinates", coordinates);
    if (coordinates.length < 3 || coordinates.length % 3 !== 0) {
      throw new DeveloperError(
        "the number of coordinates must be a multiple of 3 and at least 3"
      );
    }
    //>>includeEnd('debug');

    var length = coordinates.length;
    if (!defined(result)) {
      result = new Array(length / 3);
    } else {
      result.length = length / 3;
    }

    for (var i = 0; i < length; i += 3) {
      var longitude = coordinates[i];
      var latitude = coordinates[i + 1];
      var height = coordinates[i + 2];
      var index = i / 3;
      result[index] = Cartesian3.fromRadians(
        longitude,
        latitude,
        height,
        ellipsoid,
        result[index]
      );
    }

    return result;
  };

  /**
   * An immutable Cartesian3 instance initialized to (0.0, 0.0, 0.0).
   *
   * @type {Cartesian3}
   * @constant
   */
  Cartesian3.ZERO = Object.freeze(new Cartesian3(0.0, 0.0, 0.0));

  /**
   * An immutable Cartesian3 instance initialized to (1.0, 0.0, 0.0).
   *
   * @type {Cartesian3}
   * @constant
   */
  Cartesian3.UNIT_X = Object.freeze(new Cartesian3(1.0, 0.0, 0.0));

  /**
   * An immutable Cartesian3 instance initialized to (0.0, 1.0, 0.0).
   *
   * @type {Cartesian3}
   * @constant
   */
  Cartesian3.UNIT_Y = Object.freeze(new Cartesian3(0.0, 1.0, 0.0));

  /**
   * An immutable Cartesian3 instance initialized to (0.0, 0.0, 1.0).
   *
   * @type {Cartesian3}
   * @constant
   */
  Cartesian3.UNIT_Z = Object.freeze(new Cartesian3(0.0, 0.0, 1.0));

  /**
   * Duplicates this Cartesian3 instance.
   *
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   */
  Cartesian3.prototype.clone = function (result) {
    return Cartesian3.clone(this, result);
  };

  /**
   * Compares this Cartesian against the provided Cartesian componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartesian3} [right] The right hand side Cartesian.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Cartesian3.prototype.equals = function (right) {
    return Cartesian3.equals(this, right);
  };

  /**
   * Compares this Cartesian against the provided Cartesian componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Cartesian3} [right] The right hand side Cartesian.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartesian3.prototype.equalsEpsilon = function (
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return Cartesian3.equalsEpsilon(
      this,
      right,
      relativeEpsilon,
      absoluteEpsilon
    );
  };

  /**
   * Creates a string representing this Cartesian in the format '(x, y, z)'.
   *
   * @returns {String} A string representing this Cartesian in the format '(x, y, z)'.
   */
  Cartesian3.prototype.toString = function () {
    return "(" + this.x + ", " + this.y + ", " + this.z + ")";
  };

  var scaleToGeodeticSurfaceIntersection = new Cartesian3();
  var scaleToGeodeticSurfaceGradient = new Cartesian3();

  /**
   * Scales the provided Cartesian position along the geodetic surface normal
   * so that it is on the surface of this ellipsoid.  If the position is
   * at the center of the ellipsoid, this function returns undefined.
   *
   * @param {Cartesian3} cartesian The Cartesian position to scale.
   * @param {Cartesian3} oneOverRadii One over radii of the ellipsoid.
   * @param {Cartesian3} oneOverRadiiSquared One over radii squared of the ellipsoid.
   * @param {Number} centerToleranceSquared Tolerance for closeness to the center.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter, a new Cartesian3 instance if none was provided, or undefined if the position is at the center.
   *
   * @function scaleToGeodeticSurface
   *
   * @private
   */
  function scaleToGeodeticSurface(
    cartesian,
    oneOverRadii,
    oneOverRadiiSquared,
    centerToleranceSquared,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    if (!defined(oneOverRadii)) {
      throw new DeveloperError("oneOverRadii is required.");
    }
    if (!defined(oneOverRadiiSquared)) {
      throw new DeveloperError("oneOverRadiiSquared is required.");
    }
    if (!defined(centerToleranceSquared)) {
      throw new DeveloperError("centerToleranceSquared is required.");
    }
    //>>includeEnd('debug');

    var positionX = cartesian.x;
    var positionY = cartesian.y;
    var positionZ = cartesian.z;

    var oneOverRadiiX = oneOverRadii.x;
    var oneOverRadiiY = oneOverRadii.y;
    var oneOverRadiiZ = oneOverRadii.z;

    var x2 = positionX * positionX * oneOverRadiiX * oneOverRadiiX;
    var y2 = positionY * positionY * oneOverRadiiY * oneOverRadiiY;
    var z2 = positionZ * positionZ * oneOverRadiiZ * oneOverRadiiZ;

    // Compute the squared ellipsoid norm.
    var squaredNorm = x2 + y2 + z2;
    var ratio = Math.sqrt(1.0 / squaredNorm);

    // As an initial approximation, assume that the radial intersection is the projection point.
    var intersection = Cartesian3.multiplyByScalar(
      cartesian,
      ratio,
      scaleToGeodeticSurfaceIntersection
    );

    // If the position is near the center, the iteration will not converge.
    if (squaredNorm < centerToleranceSquared) {
      return !isFinite(ratio)
        ? undefined
        : Cartesian3.clone(intersection, result);
    }

    var oneOverRadiiSquaredX = oneOverRadiiSquared.x;
    var oneOverRadiiSquaredY = oneOverRadiiSquared.y;
    var oneOverRadiiSquaredZ = oneOverRadiiSquared.z;

    // Use the gradient at the intersection point in place of the true unit normal.
    // The difference in magnitude will be absorbed in the multiplier.
    var gradient = scaleToGeodeticSurfaceGradient;
    gradient.x = intersection.x * oneOverRadiiSquaredX * 2.0;
    gradient.y = intersection.y * oneOverRadiiSquaredY * 2.0;
    gradient.z = intersection.z * oneOverRadiiSquaredZ * 2.0;

    // Compute the initial guess at the normal vector multiplier, lambda.
    var lambda =
      ((1.0 - ratio) * Cartesian3.magnitude(cartesian)) /
      (0.5 * Cartesian3.magnitude(gradient));
    var correction = 0.0;

    var func;
    var denominator;
    var xMultiplier;
    var yMultiplier;
    var zMultiplier;
    var xMultiplier2;
    var yMultiplier2;
    var zMultiplier2;
    var xMultiplier3;
    var yMultiplier3;
    var zMultiplier3;

    do {
      lambda -= correction;

      xMultiplier = 1.0 / (1.0 + lambda * oneOverRadiiSquaredX);
      yMultiplier = 1.0 / (1.0 + lambda * oneOverRadiiSquaredY);
      zMultiplier = 1.0 / (1.0 + lambda * oneOverRadiiSquaredZ);

      xMultiplier2 = xMultiplier * xMultiplier;
      yMultiplier2 = yMultiplier * yMultiplier;
      zMultiplier2 = zMultiplier * zMultiplier;

      xMultiplier3 = xMultiplier2 * xMultiplier;
      yMultiplier3 = yMultiplier2 * yMultiplier;
      zMultiplier3 = zMultiplier2 * zMultiplier;

      func = x2 * xMultiplier2 + y2 * yMultiplier2 + z2 * zMultiplier2 - 1.0;

      // "denominator" here refers to the use of this expression in the velocity and acceleration
      // computations in the sections to follow.
      denominator =
        x2 * xMultiplier3 * oneOverRadiiSquaredX +
        y2 * yMultiplier3 * oneOverRadiiSquaredY +
        z2 * zMultiplier3 * oneOverRadiiSquaredZ;

      var derivative = -2.0 * denominator;

      correction = func / derivative;
    } while (Math.abs(func) > CesiumMath.EPSILON12);

    if (!defined(result)) {
      return new Cartesian3(
        positionX * xMultiplier,
        positionY * yMultiplier,
        positionZ * zMultiplier
      );
    }
    result.x = positionX * xMultiplier;
    result.y = positionY * yMultiplier;
    result.z = positionZ * zMultiplier;
    return result;
  }

  /**
   * A position defined by longitude, latitude, and height.
   * @alias Cartographic
   * @constructor
   *
   * @param {Number} [longitude=0.0] The longitude, in radians.
   * @param {Number} [latitude=0.0] The latitude, in radians.
   * @param {Number} [height=0.0] The height, in meters, above the ellipsoid.
   *
   * @see Ellipsoid
   */
  function Cartographic(longitude, latitude, height) {
    /**
     * The longitude, in radians.
     * @type {Number}
     * @default 0.0
     */
    this.longitude = defaultValue(longitude, 0.0);

    /**
     * The latitude, in radians.
     * @type {Number}
     * @default 0.0
     */
    this.latitude = defaultValue(latitude, 0.0);

    /**
     * The height, in meters, above the ellipsoid.
     * @type {Number}
     * @default 0.0
     */
    this.height = defaultValue(height, 0.0);
  }

  /**
   * Creates a new Cartographic instance from longitude and latitude
   * specified in radians.
   *
   * @param {Number} longitude The longitude, in radians.
   * @param {Number} latitude The latitude, in radians.
   * @param {Number} [height=0.0] The height, in meters, above the ellipsoid.
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if one was not provided.
   */
  Cartographic.fromRadians = function (longitude, latitude, height, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("longitude", longitude);
    Check.typeOf.number("latitude", latitude);
    //>>includeEnd('debug');

    height = defaultValue(height, 0.0);

    if (!defined(result)) {
      return new Cartographic(longitude, latitude, height);
    }

    result.longitude = longitude;
    result.latitude = latitude;
    result.height = height;
    return result;
  };

  /**
   * Creates a new Cartographic instance from longitude and latitude
   * specified in degrees.  The values in the resulting object will
   * be in radians.
   *
   * @param {Number} longitude The longitude, in degrees.
   * @param {Number} latitude The latitude, in degrees.
   * @param {Number} [height=0.0] The height, in meters, above the ellipsoid.
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if one was not provided.
   */
  Cartographic.fromDegrees = function (longitude, latitude, height, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("longitude", longitude);
    Check.typeOf.number("latitude", latitude);
    //>>includeEnd('debug');
    longitude = CesiumMath.toRadians(longitude);
    latitude = CesiumMath.toRadians(latitude);

    return Cartographic.fromRadians(longitude, latitude, height, result);
  };

  var cartesianToCartographicN = new Cartesian3();
  var cartesianToCartographicP = new Cartesian3();
  var cartesianToCartographicH = new Cartesian3();
  var wgs84OneOverRadii = new Cartesian3(
    1.0 / 6378137.0,
    1.0 / 6378137.0,
    1.0 / 6356752.3142451793
  );
  var wgs84OneOverRadiiSquared = new Cartesian3(
    1.0 / (6378137.0 * 6378137.0),
    1.0 / (6378137.0 * 6378137.0),
    1.0 / (6356752.3142451793 * 6356752.3142451793)
  );
  var wgs84CenterToleranceSquared = CesiumMath.EPSILON1;

  /**
   * Creates a new Cartographic instance from a Cartesian position. The values in the
   * resulting object will be in radians.
   *
   * @param {Cartesian3} cartesian The Cartesian position to convert to cartographic representation.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter, new Cartographic instance if none was provided, or undefined if the cartesian is at the center of the ellipsoid.
   */
  Cartographic.fromCartesian = function (cartesian, ellipsoid, result) {
    var oneOverRadii = defined(ellipsoid)
      ? ellipsoid.oneOverRadii
      : wgs84OneOverRadii;
    var oneOverRadiiSquared = defined(ellipsoid)
      ? ellipsoid.oneOverRadiiSquared
      : wgs84OneOverRadiiSquared;
    var centerToleranceSquared = defined(ellipsoid)
      ? ellipsoid._centerToleranceSquared
      : wgs84CenterToleranceSquared;

    //`cartesian is required.` is thrown from scaleToGeodeticSurface
    var p = scaleToGeodeticSurface(
      cartesian,
      oneOverRadii,
      oneOverRadiiSquared,
      centerToleranceSquared,
      cartesianToCartographicP
    );

    if (!defined(p)) {
      return undefined;
    }

    var n = Cartesian3.multiplyComponents(
      p,
      oneOverRadiiSquared,
      cartesianToCartographicN
    );
    n = Cartesian3.normalize(n, n);

    var h = Cartesian3.subtract(cartesian, p, cartesianToCartographicH);

    var longitude = Math.atan2(n.y, n.x);
    var latitude = Math.asin(n.z);
    var height =
      CesiumMath.sign(Cartesian3.dot(h, cartesian)) * Cartesian3.magnitude(h);

    if (!defined(result)) {
      return new Cartographic(longitude, latitude, height);
    }
    result.longitude = longitude;
    result.latitude = latitude;
    result.height = height;
    return result;
  };

  /**
   * Creates a new Cartesian3 instance from a Cartographic input. The values in the inputted
   * object should be in radians.
   *
   * @param {Cartographic} cartographic Input to be converted into a Cartesian3 output.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the position lies.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The position
   */
  Cartographic.toCartesian = function (cartographic, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartographic", cartographic);
    //>>includeEnd('debug');

    return Cartesian3.fromRadians(
      cartographic.longitude,
      cartographic.latitude,
      cartographic.height,
      ellipsoid,
      result
    );
  };

  /**
   * Duplicates a Cartographic instance.
   *
   * @param {Cartographic} cartographic The cartographic to duplicate.
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if one was not provided. (Returns undefined if cartographic is undefined)
   */
  Cartographic.clone = function (cartographic, result) {
    if (!defined(cartographic)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Cartographic(
        cartographic.longitude,
        cartographic.latitude,
        cartographic.height
      );
    }
    result.longitude = cartographic.longitude;
    result.latitude = cartographic.latitude;
    result.height = cartographic.height;
    return result;
  };

  /**
   * Compares the provided cartographics componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartographic} [left] The first cartographic.
   * @param {Cartographic} [right] The second cartographic.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Cartographic.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.longitude === right.longitude &&
        left.latitude === right.latitude &&
        left.height === right.height)
    );
  };

  /**
   * Compares the provided cartographics componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Cartographic} [left] The first cartographic.
   * @param {Cartographic} [right] The second cartographic.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartographic.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left.longitude - right.longitude) <= epsilon &&
        Math.abs(left.latitude - right.latitude) <= epsilon &&
        Math.abs(left.height - right.height) <= epsilon)
    );
  };

  /**
   * An immutable Cartographic instance initialized to (0.0, 0.0, 0.0).
   *
   * @type {Cartographic}
   * @constant
   */
  Cartographic.ZERO = Object.freeze(new Cartographic(0.0, 0.0, 0.0));

  /**
   * Duplicates this instance.
   *
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if one was not provided.
   */
  Cartographic.prototype.clone = function (result) {
    return Cartographic.clone(this, result);
  };

  /**
   * Compares the provided against this cartographic componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartographic} [right] The second cartographic.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Cartographic.prototype.equals = function (right) {
    return Cartographic.equals(this, right);
  };

  /**
   * Compares the provided against this cartographic componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Cartographic} [right] The second cartographic.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartographic.prototype.equalsEpsilon = function (right, epsilon) {
    return Cartographic.equalsEpsilon(this, right, epsilon);
  };

  /**
   * Creates a string representing this cartographic in the format '(longitude, latitude, height)'.
   *
   * @returns {String} A string representing the provided cartographic in the format '(longitude, latitude, height)'.
   */
  Cartographic.prototype.toString = function () {
    return "(" + this.longitude + ", " + this.latitude + ", " + this.height + ")";
  };

  function initialize(ellipsoid, x, y, z) {
    x = defaultValue(x, 0.0);
    y = defaultValue(y, 0.0);
    z = defaultValue(z, 0.0);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("x", x, 0.0);
    Check.typeOf.number.greaterThanOrEquals("y", y, 0.0);
    Check.typeOf.number.greaterThanOrEquals("z", z, 0.0);
    //>>includeEnd('debug');

    ellipsoid._radii = new Cartesian3(x, y, z);

    ellipsoid._radiiSquared = new Cartesian3(x * x, y * y, z * z);

    ellipsoid._radiiToTheFourth = new Cartesian3(
      x * x * x * x,
      y * y * y * y,
      z * z * z * z
    );

    ellipsoid._oneOverRadii = new Cartesian3(
      x === 0.0 ? 0.0 : 1.0 / x,
      y === 0.0 ? 0.0 : 1.0 / y,
      z === 0.0 ? 0.0 : 1.0 / z
    );

    ellipsoid._oneOverRadiiSquared = new Cartesian3(
      x === 0.0 ? 0.0 : 1.0 / (x * x),
      y === 0.0 ? 0.0 : 1.0 / (y * y),
      z === 0.0 ? 0.0 : 1.0 / (z * z)
    );

    ellipsoid._minimumRadius = Math.min(x, y, z);

    ellipsoid._maximumRadius = Math.max(x, y, z);

    ellipsoid._centerToleranceSquared = CesiumMath.EPSILON1;

    if (ellipsoid._radiiSquared.z !== 0) {
      ellipsoid._squaredXOverSquaredZ =
        ellipsoid._radiiSquared.x / ellipsoid._radiiSquared.z;
    }
  }

  /**
   * A quadratic surface defined in Cartesian coordinates by the equation
   * <code>(x / a)^2 + (y / b)^2 + (z / c)^2 = 1</code>.  Primarily used
   * by Cesium to represent the shape of planetary bodies.
   *
   * Rather than constructing this object directly, one of the provided
   * constants is normally used.
   * @alias Ellipsoid
   * @constructor
   *
   * @param {Number} [x=0] The radius in the x direction.
   * @param {Number} [y=0] The radius in the y direction.
   * @param {Number} [z=0] The radius in the z direction.
   *
   * @exception {DeveloperError} All radii components must be greater than or equal to zero.
   *
   * @see Ellipsoid.fromCartesian3
   * @see Ellipsoid.WGS84
   * @see Ellipsoid.UNIT_SPHERE
   */
  function Ellipsoid(x, y, z) {
    this._radii = undefined;
    this._radiiSquared = undefined;
    this._radiiToTheFourth = undefined;
    this._oneOverRadii = undefined;
    this._oneOverRadiiSquared = undefined;
    this._minimumRadius = undefined;
    this._maximumRadius = undefined;
    this._centerToleranceSquared = undefined;
    this._squaredXOverSquaredZ = undefined;

    initialize(this, x, y, z);
  }

  Object.defineProperties(Ellipsoid.prototype, {
    /**
     * Gets the radii of the ellipsoid.
     * @memberof Ellipsoid.prototype
     * @type {Cartesian3}
     * @readonly
     */
    radii: {
      get: function () {
        return this._radii;
      },
    },
    /**
     * Gets the squared radii of the ellipsoid.
     * @memberof Ellipsoid.prototype
     * @type {Cartesian3}
     * @readonly
     */
    radiiSquared: {
      get: function () {
        return this._radiiSquared;
      },
    },
    /**
     * Gets the radii of the ellipsoid raise to the fourth power.
     * @memberof Ellipsoid.prototype
     * @type {Cartesian3}
     * @readonly
     */
    radiiToTheFourth: {
      get: function () {
        return this._radiiToTheFourth;
      },
    },
    /**
     * Gets one over the radii of the ellipsoid.
     * @memberof Ellipsoid.prototype
     * @type {Cartesian3}
     * @readonly
     */
    oneOverRadii: {
      get: function () {
        return this._oneOverRadii;
      },
    },
    /**
     * Gets one over the squared radii of the ellipsoid.
     * @memberof Ellipsoid.prototype
     * @type {Cartesian3}
     * @readonly
     */
    oneOverRadiiSquared: {
      get: function () {
        return this._oneOverRadiiSquared;
      },
    },
    /**
     * Gets the minimum radius of the ellipsoid.
     * @memberof Ellipsoid.prototype
     * @type {Number}
     * @readonly
     */
    minimumRadius: {
      get: function () {
        return this._minimumRadius;
      },
    },
    /**
     * Gets the maximum radius of the ellipsoid.
     * @memberof Ellipsoid.prototype
     * @type {Number}
     * @readonly
     */
    maximumRadius: {
      get: function () {
        return this._maximumRadius;
      },
    },
  });

  /**
   * Duplicates an Ellipsoid instance.
   *
   * @param {Ellipsoid} ellipsoid The ellipsoid to duplicate.
   * @param {Ellipsoid} [result] The object onto which to store the result, or undefined if a new
   *                    instance should be created.
   * @returns {Ellipsoid} The cloned Ellipsoid. (Returns undefined if ellipsoid is undefined)
   */
  Ellipsoid.clone = function (ellipsoid, result) {
    if (!defined(ellipsoid)) {
      return undefined;
    }
    var radii = ellipsoid._radii;

    if (!defined(result)) {
      return new Ellipsoid(radii.x, radii.y, radii.z);
    }

    Cartesian3.clone(radii, result._radii);
    Cartesian3.clone(ellipsoid._radiiSquared, result._radiiSquared);
    Cartesian3.clone(ellipsoid._radiiToTheFourth, result._radiiToTheFourth);
    Cartesian3.clone(ellipsoid._oneOverRadii, result._oneOverRadii);
    Cartesian3.clone(ellipsoid._oneOverRadiiSquared, result._oneOverRadiiSquared);
    result._minimumRadius = ellipsoid._minimumRadius;
    result._maximumRadius = ellipsoid._maximumRadius;
    result._centerToleranceSquared = ellipsoid._centerToleranceSquared;

    return result;
  };

  /**
   * Computes an Ellipsoid from a Cartesian specifying the radii in x, y, and z directions.
   *
   * @param {Cartesian3} [cartesian=Cartesian3.ZERO] The ellipsoid's radius in the x, y, and z directions.
   * @param {Ellipsoid} [result] The object onto which to store the result, or undefined if a new
   *                    instance should be created.
   * @returns {Ellipsoid} A new Ellipsoid instance.
   *
   * @exception {DeveloperError} All radii components must be greater than or equal to zero.
   *
   * @see Ellipsoid.WGS84
   * @see Ellipsoid.UNIT_SPHERE
   */
  Ellipsoid.fromCartesian3 = function (cartesian, result) {
    if (!defined(result)) {
      result = new Ellipsoid();
    }

    if (!defined(cartesian)) {
      return result;
    }

    initialize(result, cartesian.x, cartesian.y, cartesian.z);
    return result;
  };

  /**
   * An Ellipsoid instance initialized to the WGS84 standard.
   *
   * @type {Ellipsoid}
   * @constant
   */
  Ellipsoid.WGS84 = Object.freeze(
    new Ellipsoid(6378137.0, 6378137.0, 6356752.3142451793)
  );

  /**
   * An Ellipsoid instance initialized to radii of (1.0, 1.0, 1.0).
   *
   * @type {Ellipsoid}
   * @constant
   */
  Ellipsoid.UNIT_SPHERE = Object.freeze(new Ellipsoid(1.0, 1.0, 1.0));

  /**
   * An Ellipsoid instance initialized to a sphere with the lunar radius.
   *
   * @type {Ellipsoid}
   * @constant
   */
  Ellipsoid.MOON = Object.freeze(
    new Ellipsoid(
      CesiumMath.LUNAR_RADIUS,
      CesiumMath.LUNAR_RADIUS,
      CesiumMath.LUNAR_RADIUS
    )
  );

  /**
   * Duplicates an Ellipsoid instance.
   *
   * @param {Ellipsoid} [result] The object onto which to store the result, or undefined if a new
   *                    instance should be created.
   * @returns {Ellipsoid} The cloned Ellipsoid.
   */
  Ellipsoid.prototype.clone = function (result) {
    return Ellipsoid.clone(this, result);
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Ellipsoid.packedLength = Cartesian3.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Ellipsoid} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Ellipsoid.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._radii, array, startingIndex);

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Ellipsoid} [result] The object into which to store the result.
   * @returns {Ellipsoid} The modified result parameter or a new Ellipsoid instance if one was not provided.
   */
  Ellipsoid.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var radii = Cartesian3.unpack(array, startingIndex);
    return Ellipsoid.fromCartesian3(radii, result);
  };

  /**
   * Computes the unit vector directed from the center of this ellipsoid toward the provided Cartesian position.
   * @function
   *
   * @param {Cartesian3} cartesian The Cartesian for which to to determine the geocentric normal.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if none was provided.
   */
  Ellipsoid.prototype.geocentricSurfaceNormal = Cartesian3.normalize;

  /**
   * Computes the normal of the plane tangent to the surface of the ellipsoid at the provided position.
   *
   * @param {Cartographic} cartographic The cartographic position for which to to determine the geodetic normal.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if none was provided.
   */
  Ellipsoid.prototype.geodeticSurfaceNormalCartographic = function (
    cartographic,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartographic", cartographic);
    //>>includeEnd('debug');

    var longitude = cartographic.longitude;
    var latitude = cartographic.latitude;
    var cosLatitude = Math.cos(latitude);

    var x = cosLatitude * Math.cos(longitude);
    var y = cosLatitude * Math.sin(longitude);
    var z = Math.sin(latitude);

    if (!defined(result)) {
      result = new Cartesian3();
    }
    result.x = x;
    result.y = y;
    result.z = z;
    return Cartesian3.normalize(result, result);
  };

  /**
   * Computes the normal of the plane tangent to the surface of the ellipsoid at the provided position.
   *
   * @param {Cartesian3} cartesian The Cartesian position for which to to determine the surface normal.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if none was provided.
   */
  Ellipsoid.prototype.geodeticSurfaceNormal = function (cartesian, result) {
    if (
      Cartesian3.equalsEpsilon(cartesian, Cartesian3.ZERO, CesiumMath.EPSILON14)
    ) {
      return undefined;
    }
    if (!defined(result)) {
      result = new Cartesian3();
    }
    result = Cartesian3.multiplyComponents(
      cartesian,
      this._oneOverRadiiSquared,
      result
    );
    return Cartesian3.normalize(result, result);
  };

  var cartographicToCartesianNormal = new Cartesian3();
  var cartographicToCartesianK = new Cartesian3();

  /**
   * Converts the provided cartographic to Cartesian representation.
   *
   * @param {Cartographic} cartographic The cartographic position.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if none was provided.
   *
   * @example
   * //Create a Cartographic and determine it's Cartesian representation on a WGS84 ellipsoid.
   * var position = new Cesium.Cartographic(Cesium.Math.toRadians(21), Cesium.Math.toRadians(78), 5000);
   * var cartesianPosition = Cesium.Ellipsoid.WGS84.cartographicToCartesian(position);
   */
  Ellipsoid.prototype.cartographicToCartesian = function (cartographic, result) {
    //`cartographic is required` is thrown from geodeticSurfaceNormalCartographic.
    var n = cartographicToCartesianNormal;
    var k = cartographicToCartesianK;
    this.geodeticSurfaceNormalCartographic(cartographic, n);
    Cartesian3.multiplyComponents(this._radiiSquared, n, k);
    var gamma = Math.sqrt(Cartesian3.dot(n, k));
    Cartesian3.divideByScalar(k, gamma, k);
    Cartesian3.multiplyByScalar(n, cartographic.height, n);

    if (!defined(result)) {
      result = new Cartesian3();
    }
    return Cartesian3.add(k, n, result);
  };

  /**
   * Converts the provided array of cartographics to an array of Cartesians.
   *
   * @param {Cartographic[]} cartographics An array of cartographic positions.
   * @param {Cartesian3[]} [result] The object onto which to store the result.
   * @returns {Cartesian3[]} The modified result parameter or a new Array instance if none was provided.
   *
   * @example
   * //Convert an array of Cartographics and determine their Cartesian representation on a WGS84 ellipsoid.
   * var positions = [new Cesium.Cartographic(Cesium.Math.toRadians(21), Cesium.Math.toRadians(78), 0),
   *                  new Cesium.Cartographic(Cesium.Math.toRadians(21.321), Cesium.Math.toRadians(78.123), 100),
   *                  new Cesium.Cartographic(Cesium.Math.toRadians(21.645), Cesium.Math.toRadians(78.456), 250)];
   * var cartesianPositions = Cesium.Ellipsoid.WGS84.cartographicArrayToCartesianArray(positions);
   */
  Ellipsoid.prototype.cartographicArrayToCartesianArray = function (
    cartographics,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartographics", cartographics);
    //>>includeEnd('debug')

    var length = cartographics.length;
    if (!defined(result)) {
      result = new Array(length);
    } else {
      result.length = length;
    }
    for (var i = 0; i < length; i++) {
      result[i] = this.cartographicToCartesian(cartographics[i], result[i]);
    }
    return result;
  };

  var cartesianToCartographicN$1 = new Cartesian3();
  var cartesianToCartographicP$1 = new Cartesian3();
  var cartesianToCartographicH$1 = new Cartesian3();

  /**
   * Converts the provided cartesian to cartographic representation.
   * The cartesian is undefined at the center of the ellipsoid.
   *
   * @param {Cartesian3} cartesian The Cartesian position to convert to cartographic representation.
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter, new Cartographic instance if none was provided, or undefined if the cartesian is at the center of the ellipsoid.
   *
   * @example
   * //Create a Cartesian and determine it's Cartographic representation on a WGS84 ellipsoid.
   * var position = new Cesium.Cartesian3(17832.12, 83234.52, 952313.73);
   * var cartographicPosition = Cesium.Ellipsoid.WGS84.cartesianToCartographic(position);
   */
  Ellipsoid.prototype.cartesianToCartographic = function (cartesian, result) {
    //`cartesian is required.` is thrown from scaleToGeodeticSurface
    var p = this.scaleToGeodeticSurface(cartesian, cartesianToCartographicP$1);

    if (!defined(p)) {
      return undefined;
    }

    var n = this.geodeticSurfaceNormal(p, cartesianToCartographicN$1);
    var h = Cartesian3.subtract(cartesian, p, cartesianToCartographicH$1);

    var longitude = Math.atan2(n.y, n.x);
    var latitude = Math.asin(n.z);
    var height =
      CesiumMath.sign(Cartesian3.dot(h, cartesian)) * Cartesian3.magnitude(h);

    if (!defined(result)) {
      return new Cartographic(longitude, latitude, height);
    }
    result.longitude = longitude;
    result.latitude = latitude;
    result.height = height;
    return result;
  };

  /**
   * Converts the provided array of cartesians to an array of cartographics.
   *
   * @param {Cartesian3[]} cartesians An array of Cartesian positions.
   * @param {Cartographic[]} [result] The object onto which to store the result.
   * @returns {Cartographic[]} The modified result parameter or a new Array instance if none was provided.
   *
   * @example
   * //Create an array of Cartesians and determine their Cartographic representation on a WGS84 ellipsoid.
   * var positions = [new Cesium.Cartesian3(17832.12, 83234.52, 952313.73),
   *                  new Cesium.Cartesian3(17832.13, 83234.53, 952313.73),
   *                  new Cesium.Cartesian3(17832.14, 83234.54, 952313.73)]
   * var cartographicPositions = Cesium.Ellipsoid.WGS84.cartesianArrayToCartographicArray(positions);
   */
  Ellipsoid.prototype.cartesianArrayToCartographicArray = function (
    cartesians,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    //>>includeEnd('debug');

    var length = cartesians.length;
    if (!defined(result)) {
      result = new Array(length);
    } else {
      result.length = length;
    }
    for (var i = 0; i < length; ++i) {
      result[i] = this.cartesianToCartographic(cartesians[i], result[i]);
    }
    return result;
  };

  /**
   * Scales the provided Cartesian position along the geodetic surface normal
   * so that it is on the surface of this ellipsoid.  If the position is
   * at the center of the ellipsoid, this function returns undefined.
   *
   * @param {Cartesian3} cartesian The Cartesian position to scale.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter, a new Cartesian3 instance if none was provided, or undefined if the position is at the center.
   */
  Ellipsoid.prototype.scaleToGeodeticSurface = function (cartesian, result) {
    return scaleToGeodeticSurface(
      cartesian,
      this._oneOverRadii,
      this._oneOverRadiiSquared,
      this._centerToleranceSquared,
      result
    );
  };

  /**
   * Scales the provided Cartesian position along the geocentric surface normal
   * so that it is on the surface of this ellipsoid.
   *
   * @param {Cartesian3} cartesian The Cartesian position to scale.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if none was provided.
   */
  Ellipsoid.prototype.scaleToGeocentricSurface = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    var positionX = cartesian.x;
    var positionY = cartesian.y;
    var positionZ = cartesian.z;
    var oneOverRadiiSquared = this._oneOverRadiiSquared;

    var beta =
      1.0 /
      Math.sqrt(
        positionX * positionX * oneOverRadiiSquared.x +
          positionY * positionY * oneOverRadiiSquared.y +
          positionZ * positionZ * oneOverRadiiSquared.z
      );

    return Cartesian3.multiplyByScalar(cartesian, beta, result);
  };

  /**
   * Transforms a Cartesian X, Y, Z position to the ellipsoid-scaled space by multiplying
   * its components by the result of {@link Ellipsoid#oneOverRadii}.
   *
   * @param {Cartesian3} position The position to transform.
   * @param {Cartesian3} [result] The position to which to copy the result, or undefined to create and
   *        return a new instance.
   * @returns {Cartesian3} The position expressed in the scaled space.  The returned instance is the
   *          one passed as the result parameter if it is not undefined, or a new instance of it is.
   */
  Ellipsoid.prototype.transformPositionToScaledSpace = function (
    position,
    result
  ) {
    if (!defined(result)) {
      result = new Cartesian3();
    }

    return Cartesian3.multiplyComponents(position, this._oneOverRadii, result);
  };

  /**
   * Transforms a Cartesian X, Y, Z position from the ellipsoid-scaled space by multiplying
   * its components by the result of {@link Ellipsoid#radii}.
   *
   * @param {Cartesian3} position The position to transform.
   * @param {Cartesian3} [result] The position to which to copy the result, or undefined to create and
   *        return a new instance.
   * @returns {Cartesian3} The position expressed in the unscaled space.  The returned instance is the
   *          one passed as the result parameter if it is not undefined, or a new instance of it is.
   */
  Ellipsoid.prototype.transformPositionFromScaledSpace = function (
    position,
    result
  ) {
    if (!defined(result)) {
      result = new Cartesian3();
    }

    return Cartesian3.multiplyComponents(position, this._radii, result);
  };

  /**
   * Compares this Ellipsoid against the provided Ellipsoid componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Ellipsoid} [right] The other Ellipsoid.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Ellipsoid.prototype.equals = function (right) {
    return (
      this === right ||
      (defined(right) && Cartesian3.equals(this._radii, right._radii))
    );
  };

  /**
   * Creates a string representing this Ellipsoid in the format '(radii.x, radii.y, radii.z)'.
   *
   * @returns {String} A string representing this ellipsoid in the format '(radii.x, radii.y, radii.z)'.
   */
  Ellipsoid.prototype.toString = function () {
    return this._radii.toString();
  };

  /**
   * Computes a point which is the intersection of the surface normal with the z-axis.
   *
   * @param {Cartesian3} position the position. must be on the surface of the ellipsoid.
   * @param {Number} [buffer = 0.0] A buffer to subtract from the ellipsoid size when checking if the point is inside the ellipsoid.
   *                                In earth case, with common earth datums, there is no need for this buffer since the intersection point is always (relatively) very close to the center.
   *                                In WGS84 datum, intersection point is at max z = +-42841.31151331382 (0.673% of z-axis).
   *                                Intersection point could be outside the ellipsoid if the ratio of MajorAxis / AxisOfRotation is bigger than the square root of 2
   * @param {Cartesian3} [result] The cartesian to which to copy the result, or undefined to create and
   *        return a new instance.
   * @returns {Cartesian3 | undefined} the intersection point if it's inside the ellipsoid, undefined otherwise
   *
   * @exception {DeveloperError} position is required.
   * @exception {DeveloperError} Ellipsoid must be an ellipsoid of revolution (radii.x == radii.y).
   * @exception {DeveloperError} Ellipsoid.radii.z must be greater than 0.
   */
  Ellipsoid.prototype.getSurfaceNormalIntersectionWithZAxis = function (
    position,
    buffer,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("position", position);

    if (
      !CesiumMath.equalsEpsilon(
        this._radii.x,
        this._radii.y,
        CesiumMath.EPSILON15
      )
    ) {
      throw new DeveloperError(
        "Ellipsoid must be an ellipsoid of revolution (radii.x == radii.y)"
      );
    }

    Check.typeOf.number.greaterThan("Ellipsoid.radii.z", this._radii.z, 0);
    //>>includeEnd('debug');

    buffer = defaultValue(buffer, 0.0);

    var squaredXOverSquaredZ = this._squaredXOverSquaredZ;

    if (!defined(result)) {
      result = new Cartesian3();
    }

    result.x = 0.0;
    result.y = 0.0;
    result.z = position.z * (1 - squaredXOverSquaredZ);

    if (Math.abs(result.z) >= this._radii.z - buffer) {
      return undefined;
    }

    return result;
  };

  var abscissas = [
    0.14887433898163,
    0.43339539412925,
    0.67940956829902,
    0.86506336668898,
    0.97390652851717,
    0.0,
  ];
  var weights = [
    0.29552422471475,
    0.26926671930999,
    0.21908636251598,
    0.14945134915058,
    0.066671344308684,
    0.0,
  ];

  /**
   * Compute the 10th order Gauss-Legendre Quadrature of the given definite integral.
   *
   * @param {Number} a The lower bound for the integration.
   * @param {Number} b The upper bound for the integration.
   * @param {Ellipsoid~RealValuedScalarFunction} func The function to integrate.
   * @returns {Number} The value of the integral of the given function over the given domain.
   *
   * @private
   */
  function gaussLegendreQuadrature(a, b, func) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("a", a);
    Check.typeOf.number("b", b);
    Check.typeOf.func("func", func);
    //>>includeEnd('debug');

    // The range is half of the normal range since the five weights add to one (ten weights add to two).
    // The values of the abscissas are multiplied by two to account for this.
    var xMean = 0.5 * (b + a);
    var xRange = 0.5 * (b - a);

    var sum = 0.0;
    for (var i = 0; i < 5; i++) {
      var dx = xRange * abscissas[i];
      sum += weights[i] * (func(xMean + dx) + func(xMean - dx));
    }

    // Scale the sum to the range of x.
    sum *= xRange;
    return sum;
  }

  /**
   * A real valued scalar function.
   * @callback Ellipsoid~RealValuedScalarFunction
   *
   * @param {Number} x The value used to evaluate the function.
   * @returns {Number} The value of the function at x.
   *
   * @private
   */

  /**
   * Computes an approximation of the surface area of a rectangle on the surface of an ellipsoid using
   * Gauss-Legendre 10th order quadrature.
   *
   * @param {Rectangle} rectangle The rectangle used for computing the surface area.
   * @returns {Number} The approximate area of the rectangle on the surface of this ellipsoid.
   */
  Ellipsoid.prototype.surfaceArea = function (rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');
    var minLongitude = rectangle.west;
    var maxLongitude = rectangle.east;
    var minLatitude = rectangle.south;
    var maxLatitude = rectangle.north;

    while (maxLongitude < minLongitude) {
      maxLongitude += CesiumMath.TWO_PI;
    }

    var radiiSquared = this._radiiSquared;
    var a2 = radiiSquared.x;
    var b2 = radiiSquared.y;
    var c2 = radiiSquared.z;
    var a2b2 = a2 * b2;
    return gaussLegendreQuadrature(minLatitude, maxLatitude, function (lat) {
      // phi represents the angle measured from the north pole
      // sin(phi) = sin(pi / 2 - lat) = cos(lat), cos(phi) is similar
      var sinPhi = Math.cos(lat);
      var cosPhi = Math.sin(lat);
      return (
        Math.cos(lat) *
        gaussLegendreQuadrature(minLongitude, maxLongitude, function (lon) {
          var cosTheta = Math.cos(lon);
          var sinTheta = Math.sin(lon);
          return Math.sqrt(
            a2b2 * cosPhi * cosPhi +
              c2 *
                (b2 * cosTheta * cosTheta + a2 * sinTheta * sinTheta) *
                sinPhi *
                sinPhi
          );
        })
      );
    });
  };

  /**
   * A simple map projection where longitude and latitude are linearly mapped to X and Y by multiplying
   * them by the {@link Ellipsoid#maximumRadius}.  This projection
   * is commonly known as geographic, equirectangular, equidistant cylindrical, or plate carrée.  It
   * is also known as EPSG:4326.
   *
   * @alias GeographicProjection
   * @constructor
   *
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid.
   *
   * @see WebMercatorProjection
   */
  function GeographicProjection(ellipsoid) {
    this._ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    this._semimajorAxis = this._ellipsoid.maximumRadius;
    this._oneOverSemimajorAxis = 1.0 / this._semimajorAxis;
  }

  Object.defineProperties(GeographicProjection.prototype, {
    /**
     * Gets the {@link Ellipsoid}.
     *
     * @memberof GeographicProjection.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
  });

  /**
   * Projects a set of {@link Cartographic} coordinates, in radians, to map coordinates, in meters.
   * X and Y are the longitude and latitude, respectively, multiplied by the maximum radius of the
   * ellipsoid.  Z is the unmodified height.
   *
   * @param {Cartographic} cartographic The coordinates to project.
   * @param {Cartesian3} [result] An instance into which to copy the result.  If this parameter is
   *        undefined, a new instance is created and returned.
   * @returns {Cartesian3} The projected coordinates.  If the result parameter is not undefined, the
   *          coordinates are copied there and that instance is returned.  Otherwise, a new instance is
   *          created and returned.
   */
  GeographicProjection.prototype.project = function (cartographic, result) {
    // Actually this is the special case of equidistant cylindrical called the plate carree
    var semimajorAxis = this._semimajorAxis;
    var x = cartographic.longitude * semimajorAxis;
    var y = cartographic.latitude * semimajorAxis;
    var z = cartographic.height;

    if (!defined(result)) {
      return new Cartesian3(x, y, z);
    }

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Unprojects a set of projected {@link Cartesian3} coordinates, in meters, to {@link Cartographic}
   * coordinates, in radians.  Longitude and Latitude are the X and Y coordinates, respectively,
   * divided by the maximum radius of the ellipsoid.  Height is the unmodified Z coordinate.
   *
   * @param {Cartesian3} cartesian The Cartesian position to unproject with height (z) in meters.
   * @param {Cartographic} [result] An instance into which to copy the result.  If this parameter is
   *        undefined, a new instance is created and returned.
   * @returns {Cartographic} The unprojected coordinates.  If the result parameter is not undefined, the
   *          coordinates are copied there and that instance is returned.  Otherwise, a new instance is
   *          created and returned.
   */
  GeographicProjection.prototype.unproject = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required");
    }
    //>>includeEnd('debug');

    var oneOverEarthSemimajorAxis = this._oneOverSemimajorAxis;
    var longitude = cartesian.x * oneOverEarthSemimajorAxis;
    var latitude = cartesian.y * oneOverEarthSemimajorAxis;
    var height = cartesian.z;

    if (!defined(result)) {
      return new Cartographic(longitude, latitude, height);
    }

    result.longitude = longitude;
    result.latitude = latitude;
    result.height = height;
    return result;
  };

  /**
   * This enumerated type is used in determining where, relative to the frustum, an
   * object is located. The object can either be fully contained within the frustum (INSIDE),
   * partially inside the frustum and partially outside (INTERSECTING), or somewhere entirely
   * outside of the frustum's 6 planes (OUTSIDE).
   *
   * @enum {Number}
   */
  var Intersect = {
    /**
     * Represents that an object is not contained within the frustum.
     *
     * @type {Number}
     * @constant
     */
    OUTSIDE: -1,

    /**
     * Represents that an object intersects one of the frustum's planes.
     *
     * @type {Number}
     * @constant
     */
    INTERSECTING: 0,

    /**
     * Represents that an object is fully within the frustum.
     *
     * @type {Number}
     * @constant
     */
    INSIDE: 1,
  };
  var Intersect$1 = Object.freeze(Intersect);

  /**
   * Represents the closed interval [start, stop].
   * @alias Interval
   * @constructor
   *
   * @param {Number} [start=0.0] The beginning of the interval.
   * @param {Number} [stop=0.0] The end of the interval.
   */
  function Interval(start, stop) {
    /**
     * The beginning of the interval.
     * @type {Number}
     * @default 0.0
     */
    this.start = defaultValue(start, 0.0);
    /**
     * The end of the interval.
     * @type {Number}
     * @default 0.0
     */
    this.stop = defaultValue(stop, 0.0);
  }

  /**
   * A 3x3 matrix, indexable as a column-major order array.
   * Constructor parameters are in row-major order for code readability.
   * @alias Matrix3
   * @constructor
   * @implements {ArrayLike<number>}
   *
   * @param {Number} [column0Row0=0.0] The value for column 0, row 0.
   * @param {Number} [column1Row0=0.0] The value for column 1, row 0.
   * @param {Number} [column2Row0=0.0] The value for column 2, row 0.
   * @param {Number} [column0Row1=0.0] The value for column 0, row 1.
   * @param {Number} [column1Row1=0.0] The value for column 1, row 1.
   * @param {Number} [column2Row1=0.0] The value for column 2, row 1.
   * @param {Number} [column0Row2=0.0] The value for column 0, row 2.
   * @param {Number} [column1Row2=0.0] The value for column 1, row 2.
   * @param {Number} [column2Row2=0.0] The value for column 2, row 2.
   *
   * @see Matrix3.fromColumnMajorArray
   * @see Matrix3.fromRowMajorArray
   * @see Matrix3.fromQuaternion
   * @see Matrix3.fromScale
   * @see Matrix3.fromUniformScale
   * @see Matrix2
   * @see Matrix4
   */
  function Matrix3(
    column0Row0,
    column1Row0,
    column2Row0,
    column0Row1,
    column1Row1,
    column2Row1,
    column0Row2,
    column1Row2,
    column2Row2
  ) {
    this[0] = defaultValue(column0Row0, 0.0);
    this[1] = defaultValue(column0Row1, 0.0);
    this[2] = defaultValue(column0Row2, 0.0);
    this[3] = defaultValue(column1Row0, 0.0);
    this[4] = defaultValue(column1Row1, 0.0);
    this[5] = defaultValue(column1Row2, 0.0);
    this[6] = defaultValue(column2Row0, 0.0);
    this[7] = defaultValue(column2Row1, 0.0);
    this[8] = defaultValue(column2Row2, 0.0);
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Matrix3.packedLength = 9;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Matrix3} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Matrix3.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value[0];
    array[startingIndex++] = value[1];
    array[startingIndex++] = value[2];
    array[startingIndex++] = value[3];
    array[startingIndex++] = value[4];
    array[startingIndex++] = value[5];
    array[startingIndex++] = value[6];
    array[startingIndex++] = value[7];
    array[startingIndex++] = value[8];

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Matrix3} [result] The object into which to store the result.
   * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if one was not provided.
   */
  Matrix3.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Matrix3();
    }

    result[0] = array[startingIndex++];
    result[1] = array[startingIndex++];
    result[2] = array[startingIndex++];
    result[3] = array[startingIndex++];
    result[4] = array[startingIndex++];
    result[5] = array[startingIndex++];
    result[6] = array[startingIndex++];
    result[7] = array[startingIndex++];
    result[8] = array[startingIndex++];
    return result;
  };

  /**
   * Duplicates a Matrix3 instance.
   *
   * @param {Matrix3} matrix The matrix to duplicate.
   * @param {Matrix3} [result] The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if one was not provided. (Returns undefined if matrix is undefined)
   */
  Matrix3.clone = function (matrix, result) {
    if (!defined(matrix)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Matrix3(
        matrix[0],
        matrix[3],
        matrix[6],
        matrix[1],
        matrix[4],
        matrix[7],
        matrix[2],
        matrix[5],
        matrix[8]
      );
    }
    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    result[4] = matrix[4];
    result[5] = matrix[5];
    result[6] = matrix[6];
    result[7] = matrix[7];
    result[8] = matrix[8];
    return result;
  };

  /**
   * Creates a Matrix3 from 9 consecutive elements in an array.
   *
   * @param {Number[]} array The array whose 9 consecutive elements correspond to the positions of the matrix.  Assumes column-major order.
   * @param {Number} [startingIndex=0] The offset into the array of the first element, which corresponds to first column first row position in the matrix.
   * @param {Matrix3} [result] The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Create the Matrix3:
   * // [1.0, 2.0, 3.0]
   * // [1.0, 2.0, 3.0]
   * // [1.0, 2.0, 3.0]
   *
   * var v = [1.0, 1.0, 1.0, 2.0, 2.0, 2.0, 3.0, 3.0, 3.0];
   * var m = Cesium.Matrix3.fromArray(v);
   *
   * // Create same Matrix3 with using an offset into an array
   * var v2 = [0.0, 0.0, 1.0, 1.0, 1.0, 2.0, 2.0, 2.0, 3.0, 3.0, 3.0];
   * var m2 = Cesium.Matrix3.fromArray(v2, 2);
   */
  Matrix3.fromArray = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Matrix3();
    }

    result[0] = array[startingIndex];
    result[1] = array[startingIndex + 1];
    result[2] = array[startingIndex + 2];
    result[3] = array[startingIndex + 3];
    result[4] = array[startingIndex + 4];
    result[5] = array[startingIndex + 5];
    result[6] = array[startingIndex + 6];
    result[7] = array[startingIndex + 7];
    result[8] = array[startingIndex + 8];
    return result;
  };

  /**
   * Creates a Matrix3 instance from a column-major order array.
   *
   * @param {Number[]} values The column-major order array.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   */
  Matrix3.fromColumnMajorArray = function (values, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("values", values);
    //>>includeEnd('debug');

    return Matrix3.clone(values, result);
  };

  /**
   * Creates a Matrix3 instance from a row-major order array.
   * The resulting matrix will be in column-major order.
   *
   * @param {Number[]} values The row-major order array.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   */
  Matrix3.fromRowMajorArray = function (values, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("values", values);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix3(
        values[0],
        values[1],
        values[2],
        values[3],
        values[4],
        values[5],
        values[6],
        values[7],
        values[8]
      );
    }
    result[0] = values[0];
    result[1] = values[3];
    result[2] = values[6];
    result[3] = values[1];
    result[4] = values[4];
    result[5] = values[7];
    result[6] = values[2];
    result[7] = values[5];
    result[8] = values[8];
    return result;
  };

  /**
   * Computes a 3x3 rotation matrix from the provided quaternion.
   *
   * @param {Quaternion} quaternion the quaternion to use.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The 3x3 rotation matrix from this quaternion.
   */
  Matrix3.fromQuaternion = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    //>>includeEnd('debug');

    var x2 = quaternion.x * quaternion.x;
    var xy = quaternion.x * quaternion.y;
    var xz = quaternion.x * quaternion.z;
    var xw = quaternion.x * quaternion.w;
    var y2 = quaternion.y * quaternion.y;
    var yz = quaternion.y * quaternion.z;
    var yw = quaternion.y * quaternion.w;
    var z2 = quaternion.z * quaternion.z;
    var zw = quaternion.z * quaternion.w;
    var w2 = quaternion.w * quaternion.w;

    var m00 = x2 - y2 - z2 + w2;
    var m01 = 2.0 * (xy - zw);
    var m02 = 2.0 * (xz + yw);

    var m10 = 2.0 * (xy + zw);
    var m11 = -x2 + y2 - z2 + w2;
    var m12 = 2.0 * (yz - xw);

    var m20 = 2.0 * (xz - yw);
    var m21 = 2.0 * (yz + xw);
    var m22 = -x2 - y2 + z2 + w2;

    if (!defined(result)) {
      return new Matrix3(m00, m01, m02, m10, m11, m12, m20, m21, m22);
    }
    result[0] = m00;
    result[1] = m10;
    result[2] = m20;
    result[3] = m01;
    result[4] = m11;
    result[5] = m21;
    result[6] = m02;
    result[7] = m12;
    result[8] = m22;
    return result;
  };

  /**
   * Computes a 3x3 rotation matrix from the provided headingPitchRoll. (see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles )
   *
   * @param {HeadingPitchRoll} headingPitchRoll the headingPitchRoll to use.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The 3x3 rotation matrix from this headingPitchRoll.
   */
  Matrix3.fromHeadingPitchRoll = function (headingPitchRoll, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("headingPitchRoll", headingPitchRoll);
    //>>includeEnd('debug');

    var cosTheta = Math.cos(-headingPitchRoll.pitch);
    var cosPsi = Math.cos(-headingPitchRoll.heading);
    var cosPhi = Math.cos(headingPitchRoll.roll);
    var sinTheta = Math.sin(-headingPitchRoll.pitch);
    var sinPsi = Math.sin(-headingPitchRoll.heading);
    var sinPhi = Math.sin(headingPitchRoll.roll);

    var m00 = cosTheta * cosPsi;
    var m01 = -cosPhi * sinPsi + sinPhi * sinTheta * cosPsi;
    var m02 = sinPhi * sinPsi + cosPhi * sinTheta * cosPsi;

    var m10 = cosTheta * sinPsi;
    var m11 = cosPhi * cosPsi + sinPhi * sinTheta * sinPsi;
    var m12 = -sinPhi * cosPsi + cosPhi * sinTheta * sinPsi;

    var m20 = -sinTheta;
    var m21 = sinPhi * cosTheta;
    var m22 = cosPhi * cosTheta;

    if (!defined(result)) {
      return new Matrix3(m00, m01, m02, m10, m11, m12, m20, m21, m22);
    }
    result[0] = m00;
    result[1] = m10;
    result[2] = m20;
    result[3] = m01;
    result[4] = m11;
    result[5] = m21;
    result[6] = m02;
    result[7] = m12;
    result[8] = m22;
    return result;
  };

  /**
   * Computes a Matrix3 instance representing a non-uniform scale.
   *
   * @param {Cartesian3} scale The x, y, and z scale factors.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [7.0, 0.0, 0.0]
   * //   [0.0, 8.0, 0.0]
   * //   [0.0, 0.0, 9.0]
   * var m = Cesium.Matrix3.fromScale(new Cesium.Cartesian3(7.0, 8.0, 9.0));
   */
  Matrix3.fromScale = function (scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix3(scale.x, 0.0, 0.0, 0.0, scale.y, 0.0, 0.0, 0.0, scale.z);
    }

    result[0] = scale.x;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = scale.y;
    result[5] = 0.0;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = scale.z;
    return result;
  };

  /**
   * Computes a Matrix3 instance representing a uniform scale.
   *
   * @param {Number} scale The uniform scale factor.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [2.0, 0.0, 0.0]
   * //   [0.0, 2.0, 0.0]
   * //   [0.0, 0.0, 2.0]
   * var m = Cesium.Matrix3.fromUniformScale(2.0);
   */
  Matrix3.fromUniformScale = function (scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix3(scale, 0.0, 0.0, 0.0, scale, 0.0, 0.0, 0.0, scale);
    }

    result[0] = scale;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = scale;
    result[5] = 0.0;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = scale;
    return result;
  };

  /**
   * Computes a Matrix3 instance representing the cross product equivalent matrix of a Cartesian3 vector.
   *
   * @param {Cartesian3} vector the vector on the left hand side of the cross product operation.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [0.0, -9.0,  8.0]
   * //   [9.0,  0.0, -7.0]
   * //   [-8.0, 7.0,  0.0]
   * var m = Cesium.Matrix3.fromCrossProduct(new Cesium.Cartesian3(7.0, 8.0, 9.0));
   */
  Matrix3.fromCrossProduct = function (vector, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("vector", vector);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix3(
        0.0,
        -vector.z,
        vector.y,
        vector.z,
        0.0,
        -vector.x,
        -vector.y,
        vector.x,
        0.0
      );
    }

    result[0] = 0.0;
    result[1] = vector.z;
    result[2] = -vector.y;
    result[3] = -vector.z;
    result[4] = 0.0;
    result[5] = vector.x;
    result[6] = vector.y;
    result[7] = -vector.x;
    result[8] = 0.0;
    return result;
  };

  /**
   * Creates a rotation matrix around the x-axis.
   *
   * @param {Number} angle The angle, in radians, of the rotation.  Positive angles are counterclockwise.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Rotate a point 45 degrees counterclockwise around the x-axis.
   * var p = new Cesium.Cartesian3(5, 6, 7);
   * var m = Cesium.Matrix3.fromRotationX(Cesium.Math.toRadians(45.0));
   * var rotated = Cesium.Matrix3.multiplyByVector(m, p, new Cesium.Cartesian3());
   */
  Matrix3.fromRotationX = function (angle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("angle", angle);
    //>>includeEnd('debug');

    var cosAngle = Math.cos(angle);
    var sinAngle = Math.sin(angle);

    if (!defined(result)) {
      return new Matrix3(
        1.0,
        0.0,
        0.0,
        0.0,
        cosAngle,
        -sinAngle,
        0.0,
        sinAngle,
        cosAngle
      );
    }

    result[0] = 1.0;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = cosAngle;
    result[5] = sinAngle;
    result[6] = 0.0;
    result[7] = -sinAngle;
    result[8] = cosAngle;

    return result;
  };

  /**
   * Creates a rotation matrix around the y-axis.
   *
   * @param {Number} angle The angle, in radians, of the rotation.  Positive angles are counterclockwise.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Rotate a point 45 degrees counterclockwise around the y-axis.
   * var p = new Cesium.Cartesian3(5, 6, 7);
   * var m = Cesium.Matrix3.fromRotationY(Cesium.Math.toRadians(45.0));
   * var rotated = Cesium.Matrix3.multiplyByVector(m, p, new Cesium.Cartesian3());
   */
  Matrix3.fromRotationY = function (angle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("angle", angle);
    //>>includeEnd('debug');

    var cosAngle = Math.cos(angle);
    var sinAngle = Math.sin(angle);

    if (!defined(result)) {
      return new Matrix3(
        cosAngle,
        0.0,
        sinAngle,
        0.0,
        1.0,
        0.0,
        -sinAngle,
        0.0,
        cosAngle
      );
    }

    result[0] = cosAngle;
    result[1] = 0.0;
    result[2] = -sinAngle;
    result[3] = 0.0;
    result[4] = 1.0;
    result[5] = 0.0;
    result[6] = sinAngle;
    result[7] = 0.0;
    result[8] = cosAngle;

    return result;
  };

  /**
   * Creates a rotation matrix around the z-axis.
   *
   * @param {Number} angle The angle, in radians, of the rotation.  Positive angles are counterclockwise.
   * @param {Matrix3} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix3} The modified result parameter, or a new Matrix3 instance if one was not provided.
   *
   * @example
   * // Rotate a point 45 degrees counterclockwise around the z-axis.
   * var p = new Cesium.Cartesian3(5, 6, 7);
   * var m = Cesium.Matrix3.fromRotationZ(Cesium.Math.toRadians(45.0));
   * var rotated = Cesium.Matrix3.multiplyByVector(m, p, new Cesium.Cartesian3());
   */
  Matrix3.fromRotationZ = function (angle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("angle", angle);
    //>>includeEnd('debug');

    var cosAngle = Math.cos(angle);
    var sinAngle = Math.sin(angle);

    if (!defined(result)) {
      return new Matrix3(
        cosAngle,
        -sinAngle,
        0.0,
        sinAngle,
        cosAngle,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }

    result[0] = cosAngle;
    result[1] = sinAngle;
    result[2] = 0.0;
    result[3] = -sinAngle;
    result[4] = cosAngle;
    result[5] = 0.0;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 1.0;

    return result;
  };

  /**
   * Creates an Array from the provided Matrix3 instance.
   * The array will be in column-major order.
   *
   * @param {Matrix3} matrix The matrix to use..
   * @param {Number[]} [result] The Array onto which to store the result.
   * @returns {Number[]} The modified Array parameter or a new Array instance if one was not provided.
   */
  Matrix3.toArray = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return [
        matrix[0],
        matrix[1],
        matrix[2],
        matrix[3],
        matrix[4],
        matrix[5],
        matrix[6],
        matrix[7],
        matrix[8],
      ];
    }
    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    result[4] = matrix[4];
    result[5] = matrix[5];
    result[6] = matrix[6];
    result[7] = matrix[7];
    result[8] = matrix[8];
    return result;
  };

  /**
   * Computes the array index of the element at the provided row and column.
   *
   * @param {Number} row The zero-based index of the row.
   * @param {Number} column The zero-based index of the column.
   * @returns {Number} The index of the element at the provided row and column.
   *
   * @exception {DeveloperError} row must be 0, 1, or 2.
   * @exception {DeveloperError} column must be 0, 1, or 2.
   *
   * @example
   * var myMatrix = new Cesium.Matrix3();
   * var column1Row0Index = Cesium.Matrix3.getElementIndex(1, 0);
   * var column1Row0 = myMatrix[column1Row0Index]
   * myMatrix[column1Row0Index] = 10.0;
   */
  Matrix3.getElementIndex = function (column, row) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("row", row, 0);
    Check.typeOf.number.lessThanOrEquals("row", row, 2);
    Check.typeOf.number.greaterThanOrEquals("column", column, 0);
    Check.typeOf.number.lessThanOrEquals("column", column, 2);
    //>>includeEnd('debug');

    return column * 3 + row;
  };

  /**
   * Retrieves a copy of the matrix column at the provided index as a Cartesian3 instance.
   *
   * @param {Matrix3} matrix The matrix to use.
   * @param {Number} index The zero-based index of the column to retrieve.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, or 2.
   */
  Matrix3.getColumn = function (matrix, index, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 2);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var startIndex = index * 3;
    var x = matrix[startIndex];
    var y = matrix[startIndex + 1];
    var z = matrix[startIndex + 2];

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Computes a new matrix that replaces the specified column in the provided matrix with the provided Cartesian3 instance.
   *
   * @param {Matrix3} matrix The matrix to use.
   * @param {Number} index The zero-based index of the column to set.
   * @param {Cartesian3} cartesian The Cartesian whose values will be assigned to the specified column.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, or 2.
   */
  Matrix3.setColumn = function (matrix, index, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 2);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result = Matrix3.clone(matrix, result);
    var startIndex = index * 3;
    result[startIndex] = cartesian.x;
    result[startIndex + 1] = cartesian.y;
    result[startIndex + 2] = cartesian.z;
    return result;
  };

  /**
   * Retrieves a copy of the matrix row at the provided index as a Cartesian3 instance.
   *
   * @param {Matrix3} matrix The matrix to use.
   * @param {Number} index The zero-based index of the row to retrieve.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, or 2.
   */
  Matrix3.getRow = function (matrix, index, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 2);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var x = matrix[index];
    var y = matrix[index + 3];
    var z = matrix[index + 6];

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Computes a new matrix that replaces the specified row in the provided matrix with the provided Cartesian3 instance.
   *
   * @param {Matrix3} matrix The matrix to use.
   * @param {Number} index The zero-based index of the row to set.
   * @param {Cartesian3} cartesian The Cartesian whose values will be assigned to the specified row.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, or 2.
   */
  Matrix3.setRow = function (matrix, index, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 2);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result = Matrix3.clone(matrix, result);
    result[index] = cartesian.x;
    result[index + 3] = cartesian.y;
    result[index + 6] = cartesian.z;
    return result;
  };

  var scratchColumn = new Cartesian3();

  /**
   * Extracts the non-uniform scale assuming the matrix is an affine transformation.
   *
   * @param {Matrix3} matrix The matrix.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Matrix3.getScale = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Cartesian3.magnitude(
      Cartesian3.fromElements(matrix[0], matrix[1], matrix[2], scratchColumn)
    );
    result.y = Cartesian3.magnitude(
      Cartesian3.fromElements(matrix[3], matrix[4], matrix[5], scratchColumn)
    );
    result.z = Cartesian3.magnitude(
      Cartesian3.fromElements(matrix[6], matrix[7], matrix[8], scratchColumn)
    );
    return result;
  };

  var scratchScale = new Cartesian3();

  /**
   * Computes the maximum scale assuming the matrix is an affine transformation.
   * The maximum scale is the maximum length of the column vectors.
   *
   * @param {Matrix3} matrix The matrix.
   * @returns {Number} The maximum scale.
   */
  Matrix3.getMaximumScale = function (matrix) {
    Matrix3.getScale(matrix, scratchScale);
    return Cartesian3.maximumComponent(scratchScale);
  };

  /**
   * Computes the product of two matrices.
   *
   * @param {Matrix3} left The first matrix.
   * @param {Matrix3} right The second matrix.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.multiply = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var column0Row0 =
      left[0] * right[0] + left[3] * right[1] + left[6] * right[2];
    var column0Row1 =
      left[1] * right[0] + left[4] * right[1] + left[7] * right[2];
    var column0Row2 =
      left[2] * right[0] + left[5] * right[1] + left[8] * right[2];

    var column1Row0 =
      left[0] * right[3] + left[3] * right[4] + left[6] * right[5];
    var column1Row1 =
      left[1] * right[3] + left[4] * right[4] + left[7] * right[5];
    var column1Row2 =
      left[2] * right[3] + left[5] * right[4] + left[8] * right[5];

    var column2Row0 =
      left[0] * right[6] + left[3] * right[7] + left[6] * right[8];
    var column2Row1 =
      left[1] * right[6] + left[4] * right[7] + left[7] * right[8];
    var column2Row2 =
      left[2] * right[6] + left[5] * right[7] + left[8] * right[8];

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column0Row2;
    result[3] = column1Row0;
    result[4] = column1Row1;
    result[5] = column1Row2;
    result[6] = column2Row0;
    result[7] = column2Row1;
    result[8] = column2Row2;
    return result;
  };

  /**
   * Computes the sum of two matrices.
   *
   * @param {Matrix3} left The first matrix.
   * @param {Matrix3} right The second matrix.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = left[0] + right[0];
    result[1] = left[1] + right[1];
    result[2] = left[2] + right[2];
    result[3] = left[3] + right[3];
    result[4] = left[4] + right[4];
    result[5] = left[5] + right[5];
    result[6] = left[6] + right[6];
    result[7] = left[7] + right[7];
    result[8] = left[8] + right[8];
    return result;
  };

  /**
   * Computes the difference of two matrices.
   *
   * @param {Matrix3} left The first matrix.
   * @param {Matrix3} right The second matrix.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = left[0] - right[0];
    result[1] = left[1] - right[1];
    result[2] = left[2] - right[2];
    result[3] = left[3] - right[3];
    result[4] = left[4] - right[4];
    result[5] = left[5] - right[5];
    result[6] = left[6] - right[6];
    result[7] = left[7] - right[7];
    result[8] = left[8] - right[8];
    return result;
  };

  /**
   * Computes the product of a matrix and a column vector.
   *
   * @param {Matrix3} matrix The matrix.
   * @param {Cartesian3} cartesian The column.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Matrix3.multiplyByVector = function (matrix, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var vX = cartesian.x;
    var vY = cartesian.y;
    var vZ = cartesian.z;

    var x = matrix[0] * vX + matrix[3] * vY + matrix[6] * vZ;
    var y = matrix[1] * vX + matrix[4] * vY + matrix[7] * vZ;
    var z = matrix[2] * vX + matrix[5] * vY + matrix[8] * vZ;

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Computes the product of a matrix and a scalar.
   *
   * @param {Matrix3} matrix The matrix.
   * @param {Number} scalar The number to multiply by.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.multiplyByScalar = function (matrix, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0] * scalar;
    result[1] = matrix[1] * scalar;
    result[2] = matrix[2] * scalar;
    result[3] = matrix[3] * scalar;
    result[4] = matrix[4] * scalar;
    result[5] = matrix[5] * scalar;
    result[6] = matrix[6] * scalar;
    result[7] = matrix[7] * scalar;
    result[8] = matrix[8] * scalar;
    return result;
  };

  /**
   * Computes the product of a matrix times a (non-uniform) scale, as if the scale were a scale matrix.
   *
   * @param {Matrix3} matrix The matrix on the left-hand side.
   * @param {Cartesian3} scale The non-uniform scale on the right-hand side.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   *
   *
   * @example
   * // Instead of Cesium.Matrix3.multiply(m, Cesium.Matrix3.fromScale(scale), m);
   * Cesium.Matrix3.multiplyByScale(m, scale, m);
   *
   * @see Matrix3.fromScale
   * @see Matrix3.multiplyByUniformScale
   */
  Matrix3.multiplyByScale = function (matrix, scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("scale", scale);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0] * scale.x;
    result[1] = matrix[1] * scale.x;
    result[2] = matrix[2] * scale.x;
    result[3] = matrix[3] * scale.y;
    result[4] = matrix[4] * scale.y;
    result[5] = matrix[5] * scale.y;
    result[6] = matrix[6] * scale.z;
    result[7] = matrix[7] * scale.z;
    result[8] = matrix[8] * scale.z;
    return result;
  };

  /**
   * Creates a negated copy of the provided matrix.
   *
   * @param {Matrix3} matrix The matrix to negate.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.negate = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = -matrix[0];
    result[1] = -matrix[1];
    result[2] = -matrix[2];
    result[3] = -matrix[3];
    result[4] = -matrix[4];
    result[5] = -matrix[5];
    result[6] = -matrix[6];
    result[7] = -matrix[7];
    result[8] = -matrix[8];
    return result;
  };

  /**
   * Computes the transpose of the provided matrix.
   *
   * @param {Matrix3} matrix The matrix to transpose.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.transpose = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var column0Row0 = matrix[0];
    var column0Row1 = matrix[3];
    var column0Row2 = matrix[6];
    var column1Row0 = matrix[1];
    var column1Row1 = matrix[4];
    var column1Row2 = matrix[7];
    var column2Row0 = matrix[2];
    var column2Row1 = matrix[5];
    var column2Row2 = matrix[8];

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column0Row2;
    result[3] = column1Row0;
    result[4] = column1Row1;
    result[5] = column1Row2;
    result[6] = column2Row0;
    result[7] = column2Row1;
    result[8] = column2Row2;
    return result;
  };

  var UNIT = new Cartesian3(1, 1, 1);

  /**
   * Extracts the rotation assuming the matrix is an affine transformation.
   *
   * @param {Matrix3} matrix The matrix.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter
   */
  Matrix3.getRotation = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var inverseScale = Cartesian3.divideComponents(
      UNIT,
      Matrix3.getScale(matrix, scratchScale),
      scratchScale
    );
    result = Matrix3.multiplyByScale(matrix, inverseScale, result);

    return result;
  };

  function computeFrobeniusNorm(matrix) {
    var norm = 0.0;
    for (var i = 0; i < 9; ++i) {
      var temp = matrix[i];
      norm += temp * temp;
    }

    return Math.sqrt(norm);
  }

  var rowVal = [1, 0, 0];
  var colVal = [2, 2, 1];

  function offDiagonalFrobeniusNorm(matrix) {
    // Computes the "off-diagonal" Frobenius norm.
    // Assumes matrix is symmetric.

    var norm = 0.0;
    for (var i = 0; i < 3; ++i) {
      var temp = matrix[Matrix3.getElementIndex(colVal[i], rowVal[i])];
      norm += 2.0 * temp * temp;
    }

    return Math.sqrt(norm);
  }

  function shurDecomposition(matrix, result) {
    // This routine was created based upon Matrix Computations, 3rd ed., by Golub and Van Loan,
    // section 8.4.2 The 2by2 Symmetric Schur Decomposition.
    //
    // The routine takes a matrix, which is assumed to be symmetric, and
    // finds the largest off-diagonal term, and then creates
    // a matrix (result) which can be used to help reduce it

    var tolerance = CesiumMath.EPSILON15;

    var maxDiagonal = 0.0;
    var rotAxis = 1;

    // find pivot (rotAxis) based on max diagonal of matrix
    for (var i = 0; i < 3; ++i) {
      var temp = Math.abs(matrix[Matrix3.getElementIndex(colVal[i], rowVal[i])]);
      if (temp > maxDiagonal) {
        rotAxis = i;
        maxDiagonal = temp;
      }
    }

    var c = 1.0;
    var s = 0.0;

    var p = rowVal[rotAxis];
    var q = colVal[rotAxis];

    if (Math.abs(matrix[Matrix3.getElementIndex(q, p)]) > tolerance) {
      var qq = matrix[Matrix3.getElementIndex(q, q)];
      var pp = matrix[Matrix3.getElementIndex(p, p)];
      var qp = matrix[Matrix3.getElementIndex(q, p)];

      var tau = (qq - pp) / 2.0 / qp;
      var t;

      if (tau < 0.0) {
        t = -1.0 / (-tau + Math.sqrt(1.0 + tau * tau));
      } else {
        t = 1.0 / (tau + Math.sqrt(1.0 + tau * tau));
      }

      c = 1.0 / Math.sqrt(1.0 + t * t);
      s = t * c;
    }

    result = Matrix3.clone(Matrix3.IDENTITY, result);

    result[Matrix3.getElementIndex(p, p)] = result[
      Matrix3.getElementIndex(q, q)
    ] = c;
    result[Matrix3.getElementIndex(q, p)] = s;
    result[Matrix3.getElementIndex(p, q)] = -s;

    return result;
  }

  var jMatrix = new Matrix3();
  var jMatrixTranspose = new Matrix3();

  /**
   * Computes the eigenvectors and eigenvalues of a symmetric matrix.
   * <p>
   * Returns a diagonal matrix and unitary matrix such that:
   * <code>matrix = unitary matrix * diagonal matrix * transpose(unitary matrix)</code>
   * </p>
   * <p>
   * The values along the diagonal of the diagonal matrix are the eigenvalues. The columns
   * of the unitary matrix are the corresponding eigenvectors.
   * </p>
   *
   * @param {Matrix3} matrix The matrix to decompose into diagonal and unitary matrix. Expected to be symmetric.
   * @param {Object} [result] An object with unitary and diagonal properties which are matrices onto which to store the result.
   * @returns {Object} An object with unitary and diagonal properties which are the unitary and diagonal matrices, respectively.
   *
   * @example
   * var a = //... symetric matrix
   * var result = {
   *     unitary : new Cesium.Matrix3(),
   *     diagonal : new Cesium.Matrix3()
   * };
   * Cesium.Matrix3.computeEigenDecomposition(a, result);
   *
   * var unitaryTranspose = Cesium.Matrix3.transpose(result.unitary, new Cesium.Matrix3());
   * var b = Cesium.Matrix3.multiply(result.unitary, result.diagonal, new Cesium.Matrix3());
   * Cesium.Matrix3.multiply(b, unitaryTranspose, b); // b is now equal to a
   *
   * var lambda = Cesium.Matrix3.getColumn(result.diagonal, 0, new Cesium.Cartesian3()).x;  // first eigenvalue
   * var v = Cesium.Matrix3.getColumn(result.unitary, 0, new Cesium.Cartesian3());          // first eigenvector
   * var c = Cesium.Cartesian3.multiplyByScalar(v, lambda, new Cesium.Cartesian3());        // equal to Cesium.Matrix3.multiplyByVector(a, v)
   */
  Matrix3.computeEigenDecomposition = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    //>>includeEnd('debug');

    // This routine was created based upon Matrix Computations, 3rd ed., by Golub and Van Loan,
    // section 8.4.3 The Classical Jacobi Algorithm

    var tolerance = CesiumMath.EPSILON20;
    var maxSweeps = 10;

    var count = 0;
    var sweep = 0;

    if (!defined(result)) {
      result = {};
    }

    var unitaryMatrix = (result.unitary = Matrix3.clone(
      Matrix3.IDENTITY,
      result.unitary
    ));
    var diagMatrix = (result.diagonal = Matrix3.clone(matrix, result.diagonal));

    var epsilon = tolerance * computeFrobeniusNorm(diagMatrix);

    while (sweep < maxSweeps && offDiagonalFrobeniusNorm(diagMatrix) > epsilon) {
      shurDecomposition(diagMatrix, jMatrix);
      Matrix3.transpose(jMatrix, jMatrixTranspose);
      Matrix3.multiply(diagMatrix, jMatrix, diagMatrix);
      Matrix3.multiply(jMatrixTranspose, diagMatrix, diagMatrix);
      Matrix3.multiply(unitaryMatrix, jMatrix, unitaryMatrix);

      if (++count > 2) {
        ++sweep;
        count = 0;
      }
    }

    return result;
  };

  /**
   * Computes a matrix, which contains the absolute (unsigned) values of the provided matrix's elements.
   *
   * @param {Matrix3} matrix The matrix with signed elements.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   */
  Matrix3.abs = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = Math.abs(matrix[0]);
    result[1] = Math.abs(matrix[1]);
    result[2] = Math.abs(matrix[2]);
    result[3] = Math.abs(matrix[3]);
    result[4] = Math.abs(matrix[4]);
    result[5] = Math.abs(matrix[5]);
    result[6] = Math.abs(matrix[6]);
    result[7] = Math.abs(matrix[7]);
    result[8] = Math.abs(matrix[8]);

    return result;
  };

  /**
   * Computes the determinant of the provided matrix.
   *
   * @param {Matrix3} matrix The matrix to use.
   * @returns {Number} The value of the determinant of the matrix.
   */
  Matrix3.determinant = function (matrix) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    //>>includeEnd('debug');

    var m11 = matrix[0];
    var m21 = matrix[3];
    var m31 = matrix[6];
    var m12 = matrix[1];
    var m22 = matrix[4];
    var m32 = matrix[7];
    var m13 = matrix[2];
    var m23 = matrix[5];
    var m33 = matrix[8];

    return (
      m11 * (m22 * m33 - m23 * m32) +
      m12 * (m23 * m31 - m21 * m33) +
      m13 * (m21 * m32 - m22 * m31)
    );
  };

  /**
   * Computes the inverse of the provided matrix.
   *
   * @param {Matrix3} matrix The matrix to invert.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   *
   * @exception {DeveloperError} matrix is not invertible.
   */
  Matrix3.inverse = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var m11 = matrix[0];
    var m21 = matrix[1];
    var m31 = matrix[2];
    var m12 = matrix[3];
    var m22 = matrix[4];
    var m32 = matrix[5];
    var m13 = matrix[6];
    var m23 = matrix[7];
    var m33 = matrix[8];

    var determinant = Matrix3.determinant(matrix);

    //>>includeStart('debug', pragmas.debug);
    if (Math.abs(determinant) <= CesiumMath.EPSILON15) {
      throw new DeveloperError("matrix is not invertible");
    }
    //>>includeEnd('debug');

    result[0] = m22 * m33 - m23 * m32;
    result[1] = m23 * m31 - m21 * m33;
    result[2] = m21 * m32 - m22 * m31;
    result[3] = m13 * m32 - m12 * m33;
    result[4] = m11 * m33 - m13 * m31;
    result[5] = m12 * m31 - m11 * m32;
    result[6] = m12 * m23 - m13 * m22;
    result[7] = m13 * m21 - m11 * m23;
    result[8] = m11 * m22 - m12 * m21;

    var scale = 1.0 / determinant;
    return Matrix3.multiplyByScalar(result, scale, result);
  };

  /**
   * Compares the provided matrices componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Matrix3} [left] The first matrix.
   * @param {Matrix3} [right] The second matrix.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Matrix3.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left[0] === right[0] &&
        left[1] === right[1] &&
        left[2] === right[2] &&
        left[3] === right[3] &&
        left[4] === right[4] &&
        left[5] === right[5] &&
        left[6] === right[6] &&
        left[7] === right[7] &&
        left[8] === right[8])
    );
  };

  /**
   * Compares the provided matrices componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Matrix3} [left] The first matrix.
   * @param {Matrix3} [right] The second matrix.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Matrix3.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left[0] - right[0]) <= epsilon &&
        Math.abs(left[1] - right[1]) <= epsilon &&
        Math.abs(left[2] - right[2]) <= epsilon &&
        Math.abs(left[3] - right[3]) <= epsilon &&
        Math.abs(left[4] - right[4]) <= epsilon &&
        Math.abs(left[5] - right[5]) <= epsilon &&
        Math.abs(left[6] - right[6]) <= epsilon &&
        Math.abs(left[7] - right[7]) <= epsilon &&
        Math.abs(left[8] - right[8]) <= epsilon)
    );
  };

  /**
   * An immutable Matrix3 instance initialized to the identity matrix.
   *
   * @type {Matrix3}
   * @constant
   */
  Matrix3.IDENTITY = Object.freeze(
    new Matrix3(1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0)
  );

  /**
   * An immutable Matrix3 instance initialized to the zero matrix.
   *
   * @type {Matrix3}
   * @constant
   */
  Matrix3.ZERO = Object.freeze(
    new Matrix3(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0)
  );

  /**
   * The index into Matrix3 for column 0, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN0ROW0 = 0;

  /**
   * The index into Matrix3 for column 0, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN0ROW1 = 1;

  /**
   * The index into Matrix3 for column 0, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN0ROW2 = 2;

  /**
   * The index into Matrix3 for column 1, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN1ROW0 = 3;

  /**
   * The index into Matrix3 for column 1, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN1ROW1 = 4;

  /**
   * The index into Matrix3 for column 1, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN1ROW2 = 5;

  /**
   * The index into Matrix3 for column 2, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN2ROW0 = 6;

  /**
   * The index into Matrix3 for column 2, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN2ROW1 = 7;

  /**
   * The index into Matrix3 for column 2, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix3.COLUMN2ROW2 = 8;

  Object.defineProperties(Matrix3.prototype, {
    /**
     * Gets the number of items in the collection.
     * @memberof Matrix3.prototype
     *
     * @type {Number}
     */
    length: {
      get: function () {
        return Matrix3.packedLength;
      },
    },
  });

  /**
   * Duplicates the provided Matrix3 instance.
   *
   * @param {Matrix3} [result] The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if one was not provided.
   */
  Matrix3.prototype.clone = function (result) {
    return Matrix3.clone(this, result);
  };

  /**
   * Compares this matrix to the provided matrix componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Matrix3} [right] The right hand side matrix.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Matrix3.prototype.equals = function (right) {
    return Matrix3.equals(this, right);
  };

  /**
   * @private
   */
  Matrix3.equalsArray = function (matrix, array, offset) {
    return (
      matrix[0] === array[offset] &&
      matrix[1] === array[offset + 1] &&
      matrix[2] === array[offset + 2] &&
      matrix[3] === array[offset + 3] &&
      matrix[4] === array[offset + 4] &&
      matrix[5] === array[offset + 5] &&
      matrix[6] === array[offset + 6] &&
      matrix[7] === array[offset + 7] &&
      matrix[8] === array[offset + 8]
    );
  };

  /**
   * Compares this matrix to the provided matrix componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Matrix3} [right] The right hand side matrix.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  Matrix3.prototype.equalsEpsilon = function (right, epsilon) {
    return Matrix3.equalsEpsilon(this, right, epsilon);
  };

  /**
   * Creates a string representing this Matrix with each row being
   * on a separate line and in the format '(column0, column1, column2)'.
   *
   * @returns {String} A string representing the provided Matrix with each row being on a separate line and in the format '(column0, column1, column2)'.
   */
  Matrix3.prototype.toString = function () {
    return (
      "(" +
      this[0] +
      ", " +
      this[3] +
      ", " +
      this[6] +
      ")\n" +
      "(" +
      this[1] +
      ", " +
      this[4] +
      ", " +
      this[7] +
      ")\n" +
      "(" +
      this[2] +
      ", " +
      this[5] +
      ", " +
      this[8] +
      ")"
    );
  };

  /**
   * A 4D Cartesian point.
   * @alias Cartesian4
   * @constructor
   *
   * @param {Number} [x=0.0] The X component.
   * @param {Number} [y=0.0] The Y component.
   * @param {Number} [z=0.0] The Z component.
   * @param {Number} [w=0.0] The W component.
   *
   * @see Cartesian2
   * @see Cartesian3
   * @see Packable
   */
  function Cartesian4(x, y, z, w) {
    /**
     * The X component.
     * @type {Number}
     * @default 0.0
     */
    this.x = defaultValue(x, 0.0);

    /**
     * The Y component.
     * @type {Number}
     * @default 0.0
     */
    this.y = defaultValue(y, 0.0);

    /**
     * The Z component.
     * @type {Number}
     * @default 0.0
     */
    this.z = defaultValue(z, 0.0);

    /**
     * The W component.
     * @type {Number}
     * @default 0.0
     */
    this.w = defaultValue(w, 0.0);
  }

  /**
   * Creates a Cartesian4 instance from x, y, z and w coordinates.
   *
   * @param {Number} x The x coordinate.
   * @param {Number} y The y coordinate.
   * @param {Number} z The z coordinate.
   * @param {Number} w The w coordinate.
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter or a new Cartesian4 instance if one was not provided.
   */
  Cartesian4.fromElements = function (x, y, z, w, result) {
    if (!defined(result)) {
      return new Cartesian4(x, y, z, w);
    }

    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  /**
   * Creates a Cartesian4 instance from a {@link Color}. <code>red</code>, <code>green</code>, <code>blue</code>,
   * and <code>alpha</code> map to <code>x</code>, <code>y</code>, <code>z</code>, and <code>w</code>, respectively.
   *
   * @param {Color} color The source color.
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter or a new Cartesian4 instance if one was not provided.
   */
  Cartesian4.fromColor = function (color, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("color", color);
    //>>includeEnd('debug');
    if (!defined(result)) {
      return new Cartesian4(color.red, color.green, color.blue, color.alpha);
    }

    result.x = color.red;
    result.y = color.green;
    result.z = color.blue;
    result.w = color.alpha;
    return result;
  };

  /**
   * Duplicates a Cartesian4 instance.
   *
   * @param {Cartesian4} cartesian The Cartesian to duplicate.
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter or a new Cartesian4 instance if one was not provided. (Returns undefined if cartesian is undefined)
   */
  Cartesian4.clone = function (cartesian, result) {
    if (!defined(cartesian)) {
      return undefined;
    }

    if (!defined(result)) {
      return new Cartesian4(cartesian.x, cartesian.y, cartesian.z, cartesian.w);
    }

    result.x = cartesian.x;
    result.y = cartesian.y;
    result.z = cartesian.z;
    result.w = cartesian.w;
    return result;
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Cartesian4.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Cartesian4} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Cartesian4.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.x;
    array[startingIndex++] = value.y;
    array[startingIndex++] = value.z;
    array[startingIndex] = value.w;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Cartesian4} [result] The object into which to store the result.
   * @returns {Cartesian4}  The modified result parameter or a new Cartesian4 instance if one was not provided.
   */
  Cartesian4.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Cartesian4();
    }
    result.x = array[startingIndex++];
    result.y = array[startingIndex++];
    result.z = array[startingIndex++];
    result.w = array[startingIndex];
    return result;
  };

  /**
       * Flattens an array of Cartesian4s into and array of components.
       *
       * @param {Cartesian4[]} array The array of cartesians to pack.
       * @param {Number[]} [result] The array onto which to store the result. If this is a typed array, it must have array.length * 4 components, else a {@link DeveloperError} will be thrown. If it is a regular array, it will be resized to have (array.length * 4) elements.

       * @returns {Number[]} The packed array.
       */
  Cartesian4.packArray = function (array, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    var length = array.length;
    var resultLength = length * 4;
    if (!defined(result)) {
      result = new Array(resultLength);
    } else if (!Array.isArray(result) && result.length !== resultLength) {
      throw new DeveloperError(
        "If result is a typed array, it must have exactly array.length * 4 elements"
      );
    } else if (result.length !== resultLength) {
      result.length = resultLength;
    }

    for (var i = 0; i < length; ++i) {
      Cartesian4.pack(array[i], result, i * 4);
    }
    return result;
  };

  /**
   * Unpacks an array of cartesian components into and array of Cartesian4s.
   *
   * @param {Number[]} array The array of components to unpack.
   * @param {Cartesian4[]} [result] The array onto which to store the result.
   * @returns {Cartesian4[]} The unpacked array.
   */
  Cartesian4.unpackArray = function (array, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    Check.typeOf.number.greaterThanOrEquals("array.length", array.length, 4);
    if (array.length % 4 !== 0) {
      throw new DeveloperError("array length must be a multiple of 4.");
    }
    //>>includeEnd('debug');

    var length = array.length;
    if (!defined(result)) {
      result = new Array(length / 4);
    } else {
      result.length = length / 4;
    }

    for (var i = 0; i < length; i += 4) {
      var index = i / 4;
      result[index] = Cartesian4.unpack(array, i, result[index]);
    }
    return result;
  };

  /**
   * Creates a Cartesian4 from four consecutive elements in an array.
   * @function
   *
   * @param {Number[]} array The array whose four consecutive elements correspond to the x, y, z, and w components, respectively.
   * @param {Number} [startingIndex=0] The offset into the array of the first element, which corresponds to the x component.
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4}  The modified result parameter or a new Cartesian4 instance if one was not provided.
   *
   * @example
   * // Create a Cartesian4 with (1.0, 2.0, 3.0, 4.0)
   * var v = [1.0, 2.0, 3.0, 4.0];
   * var p = Cesium.Cartesian4.fromArray(v);
   *
   * // Create a Cartesian4 with (1.0, 2.0, 3.0, 4.0) using an offset into an array
   * var v2 = [0.0, 0.0, 1.0, 2.0, 3.0, 4.0];
   * var p2 = Cesium.Cartesian4.fromArray(v2, 2);
   */
  Cartesian4.fromArray = Cartesian4.unpack;

  /**
   * Computes the value of the maximum component for the supplied Cartesian.
   *
   * @param {Cartesian4} cartesian The cartesian to use.
   * @returns {Number} The value of the maximum component.
   */
  Cartesian4.maximumComponent = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return Math.max(cartesian.x, cartesian.y, cartesian.z, cartesian.w);
  };

  /**
   * Computes the value of the minimum component for the supplied Cartesian.
   *
   * @param {Cartesian4} cartesian The cartesian to use.
   * @returns {Number} The value of the minimum component.
   */
  Cartesian4.minimumComponent = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return Math.min(cartesian.x, cartesian.y, cartesian.z, cartesian.w);
  };

  /**
   * Compares two Cartesians and computes a Cartesian which contains the minimum components of the supplied Cartesians.
   *
   * @param {Cartesian4} first A cartesian to compare.
   * @param {Cartesian4} second A cartesian to compare.
   * @param {Cartesian4} result The object into which to store the result.
   * @returns {Cartesian4} A cartesian with the minimum components.
   */
  Cartesian4.minimumByComponent = function (first, second, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("first", first);
    Check.typeOf.object("second", second);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.min(first.x, second.x);
    result.y = Math.min(first.y, second.y);
    result.z = Math.min(first.z, second.z);
    result.w = Math.min(first.w, second.w);

    return result;
  };

  /**
   * Compares two Cartesians and computes a Cartesian which contains the maximum components of the supplied Cartesians.
   *
   * @param {Cartesian4} first A cartesian to compare.
   * @param {Cartesian4} second A cartesian to compare.
   * @param {Cartesian4} result The object into which to store the result.
   * @returns {Cartesian4} A cartesian with the maximum components.
   */
  Cartesian4.maximumByComponent = function (first, second, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("first", first);
    Check.typeOf.object("second", second);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.max(first.x, second.x);
    result.y = Math.max(first.y, second.y);
    result.z = Math.max(first.z, second.z);
    result.w = Math.max(first.w, second.w);

    return result;
  };

  /**
   * Computes the provided Cartesian's squared magnitude.
   *
   * @param {Cartesian4} cartesian The Cartesian instance whose squared magnitude is to be computed.
   * @returns {Number} The squared magnitude.
   */
  Cartesian4.magnitudeSquared = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return (
      cartesian.x * cartesian.x +
      cartesian.y * cartesian.y +
      cartesian.z * cartesian.z +
      cartesian.w * cartesian.w
    );
  };

  /**
   * Computes the Cartesian's magnitude (length).
   *
   * @param {Cartesian4} cartesian The Cartesian instance whose magnitude is to be computed.
   * @returns {Number} The magnitude.
   */
  Cartesian4.magnitude = function (cartesian) {
    return Math.sqrt(Cartesian4.magnitudeSquared(cartesian));
  };

  var distanceScratch$1 = new Cartesian4();

  /**
   * Computes the 4-space distance between two points.
   *
   * @param {Cartesian4} left The first point to compute the distance from.
   * @param {Cartesian4} right The second point to compute the distance to.
   * @returns {Number} The distance between two points.
   *
   * @example
   * // Returns 1.0
   * var d = Cesium.Cartesian4.distance(
   *   new Cesium.Cartesian4(1.0, 0.0, 0.0, 0.0),
   *   new Cesium.Cartesian4(2.0, 0.0, 0.0, 0.0));
   */
  Cartesian4.distance = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian4.subtract(left, right, distanceScratch$1);
    return Cartesian4.magnitude(distanceScratch$1);
  };

  /**
   * Computes the squared distance between two points.  Comparing squared distances
   * using this function is more efficient than comparing distances using {@link Cartesian4#distance}.
   *
   * @param {Cartesian4} left The first point to compute the distance from.
   * @param {Cartesian4} right The second point to compute the distance to.
   * @returns {Number} The distance between two points.
   *
   * @example
   * // Returns 4.0, not 2.0
   * var d = Cesium.Cartesian4.distance(
   *   new Cesium.Cartesian4(1.0, 0.0, 0.0, 0.0),
   *   new Cesium.Cartesian4(3.0, 0.0, 0.0, 0.0));
   */
  Cartesian4.distanceSquared = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian4.subtract(left, right, distanceScratch$1);
    return Cartesian4.magnitudeSquared(distanceScratch$1);
  };

  /**
   * Computes the normalized form of the supplied Cartesian.
   *
   * @param {Cartesian4} cartesian The Cartesian to be normalized.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.normalize = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var magnitude = Cartesian4.magnitude(cartesian);

    result.x = cartesian.x / magnitude;
    result.y = cartesian.y / magnitude;
    result.z = cartesian.z / magnitude;
    result.w = cartesian.w / magnitude;

    //>>includeStart('debug', pragmas.debug);
    if (
      isNaN(result.x) ||
      isNaN(result.y) ||
      isNaN(result.z) ||
      isNaN(result.w)
    ) {
      throw new DeveloperError("normalized result is not a number");
    }
    //>>includeEnd('debug');

    return result;
  };

  /**
   * Computes the dot (scalar) product of two Cartesians.
   *
   * @param {Cartesian4} left The first Cartesian.
   * @param {Cartesian4} right The second Cartesian.
   * @returns {Number} The dot product.
   */
  Cartesian4.dot = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    return (
      left.x * right.x + left.y * right.y + left.z * right.z + left.w * right.w
    );
  };

  /**
   * Computes the componentwise product of two Cartesians.
   *
   * @param {Cartesian4} left The first Cartesian.
   * @param {Cartesian4} right The second Cartesian.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.multiplyComponents = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x * right.x;
    result.y = left.y * right.y;
    result.z = left.z * right.z;
    result.w = left.w * right.w;
    return result;
  };

  /**
   * Computes the componentwise quotient of two Cartesians.
   *
   * @param {Cartesian4} left The first Cartesian.
   * @param {Cartesian4} right The second Cartesian.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.divideComponents = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x / right.x;
    result.y = left.y / right.y;
    result.z = left.z / right.z;
    result.w = left.w / right.w;
    return result;
  };

  /**
   * Computes the componentwise sum of two Cartesians.
   *
   * @param {Cartesian4} left The first Cartesian.
   * @param {Cartesian4} right The second Cartesian.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x + right.x;
    result.y = left.y + right.y;
    result.z = left.z + right.z;
    result.w = left.w + right.w;
    return result;
  };

  /**
   * Computes the componentwise difference of two Cartesians.
   *
   * @param {Cartesian4} left The first Cartesian.
   * @param {Cartesian4} right The second Cartesian.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x - right.x;
    result.y = left.y - right.y;
    result.z = left.z - right.z;
    result.w = left.w - right.w;
    return result;
  };

  /**
   * Multiplies the provided Cartesian componentwise by the provided scalar.
   *
   * @param {Cartesian4} cartesian The Cartesian to be scaled.
   * @param {Number} scalar The scalar to multiply with.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.multiplyByScalar = function (cartesian, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = cartesian.x * scalar;
    result.y = cartesian.y * scalar;
    result.z = cartesian.z * scalar;
    result.w = cartesian.w * scalar;
    return result;
  };

  /**
   * Divides the provided Cartesian componentwise by the provided scalar.
   *
   * @param {Cartesian4} cartesian The Cartesian to be divided.
   * @param {Number} scalar The scalar to divide by.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.divideByScalar = function (cartesian, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = cartesian.x / scalar;
    result.y = cartesian.y / scalar;
    result.z = cartesian.z / scalar;
    result.w = cartesian.w / scalar;
    return result;
  };

  /**
   * Negates the provided Cartesian.
   *
   * @param {Cartesian4} cartesian The Cartesian to be negated.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.negate = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = -cartesian.x;
    result.y = -cartesian.y;
    result.z = -cartesian.z;
    result.w = -cartesian.w;
    return result;
  };

  /**
   * Computes the absolute value of the provided Cartesian.
   *
   * @param {Cartesian4} cartesian The Cartesian whose absolute value is to be computed.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.abs = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.abs(cartesian.x);
    result.y = Math.abs(cartesian.y);
    result.z = Math.abs(cartesian.z);
    result.w = Math.abs(cartesian.w);
    return result;
  };

  var lerpScratch$1 = new Cartesian4();
  /**
   * Computes the linear interpolation or extrapolation at t using the provided cartesians.
   *
   * @param {Cartesian4} start The value corresponding to t at 0.0.
   * @param {Cartesian4}end The value corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Cartesian4.lerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    Cartesian4.multiplyByScalar(end, t, lerpScratch$1);
    result = Cartesian4.multiplyByScalar(start, 1.0 - t, result);
    return Cartesian4.add(lerpScratch$1, result, result);
  };

  var mostOrthogonalAxisScratch$1 = new Cartesian4();
  /**
   * Returns the axis that is most orthogonal to the provided Cartesian.
   *
   * @param {Cartesian4} cartesian The Cartesian on which to find the most orthogonal axis.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The most orthogonal axis.
   */
  Cartesian4.mostOrthogonalAxis = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var f = Cartesian4.normalize(cartesian, mostOrthogonalAxisScratch$1);
    Cartesian4.abs(f, f);

    if (f.x <= f.y) {
      if (f.x <= f.z) {
        if (f.x <= f.w) {
          result = Cartesian4.clone(Cartesian4.UNIT_X, result);
        } else {
          result = Cartesian4.clone(Cartesian4.UNIT_W, result);
        }
      } else if (f.z <= f.w) {
        result = Cartesian4.clone(Cartesian4.UNIT_Z, result);
      } else {
        result = Cartesian4.clone(Cartesian4.UNIT_W, result);
      }
    } else if (f.y <= f.z) {
      if (f.y <= f.w) {
        result = Cartesian4.clone(Cartesian4.UNIT_Y, result);
      } else {
        result = Cartesian4.clone(Cartesian4.UNIT_W, result);
      }
    } else if (f.z <= f.w) {
      result = Cartesian4.clone(Cartesian4.UNIT_Z, result);
    } else {
      result = Cartesian4.clone(Cartesian4.UNIT_W, result);
    }

    return result;
  };

  /**
   * Compares the provided Cartesians componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartesian4} [left] The first Cartesian.
   * @param {Cartesian4} [right] The second Cartesian.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Cartesian4.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.x === right.x &&
        left.y === right.y &&
        left.z === right.z &&
        left.w === right.w)
    );
  };

  /**
   * @private
   */
  Cartesian4.equalsArray = function (cartesian, array, offset) {
    return (
      cartesian.x === array[offset] &&
      cartesian.y === array[offset + 1] &&
      cartesian.z === array[offset + 2] &&
      cartesian.w === array[offset + 3]
    );
  };

  /**
   * Compares the provided Cartesians componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Cartesian4} [left] The first Cartesian.
   * @param {Cartesian4} [right] The second Cartesian.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartesian4.equalsEpsilon = function (
    left,
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        CesiumMath.equalsEpsilon(
          left.x,
          right.x,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.y,
          right.y,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.z,
          right.z,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.w,
          right.w,
          relativeEpsilon,
          absoluteEpsilon
        ))
    );
  };

  /**
   * An immutable Cartesian4 instance initialized to (0.0, 0.0, 0.0, 0.0).
   *
   * @type {Cartesian4}
   * @constant
   */
  Cartesian4.ZERO = Object.freeze(new Cartesian4(0.0, 0.0, 0.0, 0.0));

  /**
   * An immutable Cartesian4 instance initialized to (1.0, 0.0, 0.0, 0.0).
   *
   * @type {Cartesian4}
   * @constant
   */
  Cartesian4.UNIT_X = Object.freeze(new Cartesian4(1.0, 0.0, 0.0, 0.0));

  /**
   * An immutable Cartesian4 instance initialized to (0.0, 1.0, 0.0, 0.0).
   *
   * @type {Cartesian4}
   * @constant
   */
  Cartesian4.UNIT_Y = Object.freeze(new Cartesian4(0.0, 1.0, 0.0, 0.0));

  /**
   * An immutable Cartesian4 instance initialized to (0.0, 0.0, 1.0, 0.0).
   *
   * @type {Cartesian4}
   * @constant
   */
  Cartesian4.UNIT_Z = Object.freeze(new Cartesian4(0.0, 0.0, 1.0, 0.0));

  /**
   * An immutable Cartesian4 instance initialized to (0.0, 0.0, 0.0, 1.0).
   *
   * @type {Cartesian4}
   * @constant
   */
  Cartesian4.UNIT_W = Object.freeze(new Cartesian4(0.0, 0.0, 0.0, 1.0));

  /**
   * Duplicates this Cartesian4 instance.
   *
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter or a new Cartesian4 instance if one was not provided.
   */
  Cartesian4.prototype.clone = function (result) {
    return Cartesian4.clone(this, result);
  };

  /**
   * Compares this Cartesian against the provided Cartesian componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartesian4} [right] The right hand side Cartesian.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Cartesian4.prototype.equals = function (right) {
    return Cartesian4.equals(this, right);
  };

  /**
   * Compares this Cartesian against the provided Cartesian componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Cartesian4} [right] The right hand side Cartesian.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartesian4.prototype.equalsEpsilon = function (
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return Cartesian4.equalsEpsilon(
      this,
      right,
      relativeEpsilon,
      absoluteEpsilon
    );
  };

  /**
   * Creates a string representing this Cartesian in the format '(x, y, z, w)'.
   *
   * @returns {String} A string representing the provided Cartesian in the format '(x, y, z, w)'.
   */
  Cartesian4.prototype.toString = function () {
    return "(" + this.x + ", " + this.y + ", " + this.z + ", " + this.w + ")";
  };

  var scratchFloatArray = new Float32Array(1);
  var SHIFT_LEFT_8 = 256.0;
  var SHIFT_LEFT_16 = 65536.0;
  var SHIFT_LEFT_24 = 16777216.0;

  var SHIFT_RIGHT_8 = 1.0 / SHIFT_LEFT_8;
  var SHIFT_RIGHT_16 = 1.0 / SHIFT_LEFT_16;
  var SHIFT_RIGHT_24 = 1.0 / SHIFT_LEFT_24;

  var BIAS = 38.0;

  /**
   * Packs an arbitrary floating point value to 4 values representable using uint8.
   *
   * @param {Number} value A floating point number
   * @param {Cartesian4} [result] The Cartesian4 that will contain the packed float.
   * @returns {Cartesian4} A Cartesian4 representing the float packed to values in x, y, z, and w.
   */
  Cartesian4.packFloat = function (value, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("value", value);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian4();
    }

    // Force the value to 32 bit precision
    scratchFloatArray[0] = value;
    value = scratchFloatArray[0];

    if (value === 0.0) {
      return Cartesian4.clone(Cartesian4.ZERO, result);
    }

    var sign = value < 0.0 ? 1.0 : 0.0;
    var exponent;

    if (!isFinite(value)) {
      value = 0.1;
      exponent = BIAS;
    } else {
      value = Math.abs(value);
      exponent = Math.floor(CesiumMath.logBase(value, 10)) + 1.0;
      value = value / Math.pow(10.0, exponent);
    }

    var temp = value * SHIFT_LEFT_8;
    result.x = Math.floor(temp);
    temp = (temp - result.x) * SHIFT_LEFT_8;
    result.y = Math.floor(temp);
    temp = (temp - result.y) * SHIFT_LEFT_8;
    result.z = Math.floor(temp);
    result.w = (exponent + BIAS) * 2.0 + sign;

    return result;
  };

  /**
   * Unpacks a float packed using Cartesian4.packFloat.
   *
   * @param {Cartesian4} packedFloat A Cartesian4 containing a float packed to 4 values representable using uint8.
   * @returns {Number} The unpacked float.
   * @private
   */
  Cartesian4.unpackFloat = function (packedFloat) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("packedFloat", packedFloat);
    //>>includeEnd('debug');

    var temp = packedFloat.w / 2.0;
    var exponent = Math.floor(temp);
    var sign = (temp - exponent) * 2.0;
    exponent = exponent - BIAS;

    sign = sign * 2.0 - 1.0;
    sign = -sign;

    if (exponent >= BIAS) {
      return sign < 0.0 ? Number.NEGATIVE_INFINITY : Number.POSITIVE_INFINITY;
    }

    var unpacked = sign * packedFloat.x * SHIFT_RIGHT_8;
    unpacked += sign * packedFloat.y * SHIFT_RIGHT_16;
    unpacked += sign * packedFloat.z * SHIFT_RIGHT_24;

    return unpacked * Math.pow(10.0, exponent);
  };

  /**
   * Constructs an exception object that is thrown due to an error that can occur at runtime, e.g.,
   * out of memory, could not compile shader, etc.  If a function may throw this
   * exception, the calling code should be prepared to catch it.
   * <br /><br />
   * On the other hand, a {@link DeveloperError} indicates an exception due
   * to a developer error, e.g., invalid argument, that usually indicates a bug in the
   * calling code.
   *
   * @alias RuntimeError
   * @constructor
   * @extends Error
   *
   * @param {String} [message] The error message for this exception.
   *
   * @see DeveloperError
   */
  function RuntimeError(message) {
    /**
     * 'RuntimeError' indicating that this exception was thrown due to a runtime error.
     * @type {String}
     * @readonly
     */
    this.name = "RuntimeError";

    /**
     * The explanation for why this exception was thrown.
     * @type {String}
     * @readonly
     */
    this.message = message;

    //Browsers such as IE don't have a stack property until you actually throw the error.
    var stack;
    try {
      throw new Error();
    } catch (e) {
      stack = e.stack;
    }

    /**
     * The stack trace of this exception, if available.
     * @type {String}
     * @readonly
     */
    this.stack = stack;
  }

  if (defined(Object.create)) {
    RuntimeError.prototype = Object.create(Error.prototype);
    RuntimeError.prototype.constructor = RuntimeError;
  }

  RuntimeError.prototype.toString = function () {
    var str = this.name + ": " + this.message;

    if (defined(this.stack)) {
      str += "\n" + this.stack.toString();
    }

    return str;
  };

  /**
   * A 4x4 matrix, indexable as a column-major order array.
   * Constructor parameters are in row-major order for code readability.
   * @alias Matrix4
   * @constructor
   * @implements {ArrayLike<number>}
   *
   * @param {Number} [column0Row0=0.0] The value for column 0, row 0.
   * @param {Number} [column1Row0=0.0] The value for column 1, row 0.
   * @param {Number} [column2Row0=0.0] The value for column 2, row 0.
   * @param {Number} [column3Row0=0.0] The value for column 3, row 0.
   * @param {Number} [column0Row1=0.0] The value for column 0, row 1.
   * @param {Number} [column1Row1=0.0] The value for column 1, row 1.
   * @param {Number} [column2Row1=0.0] The value for column 2, row 1.
   * @param {Number} [column3Row1=0.0] The value for column 3, row 1.
   * @param {Number} [column0Row2=0.0] The value for column 0, row 2.
   * @param {Number} [column1Row2=0.0] The value for column 1, row 2.
   * @param {Number} [column2Row2=0.0] The value for column 2, row 2.
   * @param {Number} [column3Row2=0.0] The value for column 3, row 2.
   * @param {Number} [column0Row3=0.0] The value for column 0, row 3.
   * @param {Number} [column1Row3=0.0] The value for column 1, row 3.
   * @param {Number} [column2Row3=0.0] The value for column 2, row 3.
   * @param {Number} [column3Row3=0.0] The value for column 3, row 3.
   *
   * @see Matrix4.fromColumnMajorArray
   * @see Matrix4.fromRowMajorArray
   * @see Matrix4.fromRotationTranslation
   * @see Matrix4.fromTranslationRotationScale
   * @see Matrix4.fromTranslationQuaternionRotationScale
   * @see Matrix4.fromTranslation
   * @see Matrix4.fromScale
   * @see Matrix4.fromUniformScale
   * @see Matrix4.fromCamera
   * @see Matrix4.computePerspectiveFieldOfView
   * @see Matrix4.computeOrthographicOffCenter
   * @see Matrix4.computePerspectiveOffCenter
   * @see Matrix4.computeInfinitePerspectiveOffCenter
   * @see Matrix4.computeViewportTransformation
   * @see Matrix4.computeView
   * @see Matrix2
   * @see Matrix3
   * @see Packable
   */
  function Matrix4(
    column0Row0,
    column1Row0,
    column2Row0,
    column3Row0,
    column0Row1,
    column1Row1,
    column2Row1,
    column3Row1,
    column0Row2,
    column1Row2,
    column2Row2,
    column3Row2,
    column0Row3,
    column1Row3,
    column2Row3,
    column3Row3
  ) {
    this[0] = defaultValue(column0Row0, 0.0);
    this[1] = defaultValue(column0Row1, 0.0);
    this[2] = defaultValue(column0Row2, 0.0);
    this[3] = defaultValue(column0Row3, 0.0);
    this[4] = defaultValue(column1Row0, 0.0);
    this[5] = defaultValue(column1Row1, 0.0);
    this[6] = defaultValue(column1Row2, 0.0);
    this[7] = defaultValue(column1Row3, 0.0);
    this[8] = defaultValue(column2Row0, 0.0);
    this[9] = defaultValue(column2Row1, 0.0);
    this[10] = defaultValue(column2Row2, 0.0);
    this[11] = defaultValue(column2Row3, 0.0);
    this[12] = defaultValue(column3Row0, 0.0);
    this[13] = defaultValue(column3Row1, 0.0);
    this[14] = defaultValue(column3Row2, 0.0);
    this[15] = defaultValue(column3Row3, 0.0);
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Matrix4.packedLength = 16;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Matrix4} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Matrix4.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value[0];
    array[startingIndex++] = value[1];
    array[startingIndex++] = value[2];
    array[startingIndex++] = value[3];
    array[startingIndex++] = value[4];
    array[startingIndex++] = value[5];
    array[startingIndex++] = value[6];
    array[startingIndex++] = value[7];
    array[startingIndex++] = value[8];
    array[startingIndex++] = value[9];
    array[startingIndex++] = value[10];
    array[startingIndex++] = value[11];
    array[startingIndex++] = value[12];
    array[startingIndex++] = value[13];
    array[startingIndex++] = value[14];
    array[startingIndex] = value[15];

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Matrix4} [result] The object into which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if one was not provided.
   */
  Matrix4.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Matrix4();
    }

    result[0] = array[startingIndex++];
    result[1] = array[startingIndex++];
    result[2] = array[startingIndex++];
    result[3] = array[startingIndex++];
    result[4] = array[startingIndex++];
    result[5] = array[startingIndex++];
    result[6] = array[startingIndex++];
    result[7] = array[startingIndex++];
    result[8] = array[startingIndex++];
    result[9] = array[startingIndex++];
    result[10] = array[startingIndex++];
    result[11] = array[startingIndex++];
    result[12] = array[startingIndex++];
    result[13] = array[startingIndex++];
    result[14] = array[startingIndex++];
    result[15] = array[startingIndex];
    return result;
  };

  /**
   * Duplicates a Matrix4 instance.
   *
   * @param {Matrix4} matrix The matrix to duplicate.
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if one was not provided. (Returns undefined if matrix is undefined)
   */
  Matrix4.clone = function (matrix, result) {
    if (!defined(matrix)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Matrix4(
        matrix[0],
        matrix[4],
        matrix[8],
        matrix[12],
        matrix[1],
        matrix[5],
        matrix[9],
        matrix[13],
        matrix[2],
        matrix[6],
        matrix[10],
        matrix[14],
        matrix[3],
        matrix[7],
        matrix[11],
        matrix[15]
      );
    }
    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    result[4] = matrix[4];
    result[5] = matrix[5];
    result[6] = matrix[6];
    result[7] = matrix[7];
    result[8] = matrix[8];
    result[9] = matrix[9];
    result[10] = matrix[10];
    result[11] = matrix[11];
    result[12] = matrix[12];
    result[13] = matrix[13];
    result[14] = matrix[14];
    result[15] = matrix[15];
    return result;
  };

  /**
   * Creates a Matrix4 from 16 consecutive elements in an array.
   * @function
   *
   * @param {Number[]} array The array whose 16 consecutive elements correspond to the positions of the matrix.  Assumes column-major order.
   * @param {Number} [startingIndex=0] The offset into the array of the first element, which corresponds to first column first row position in the matrix.
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if one was not provided.
   *
   * @example
   * // Create the Matrix4:
   * // [1.0, 2.0, 3.0, 4.0]
   * // [1.0, 2.0, 3.0, 4.0]
   * // [1.0, 2.0, 3.0, 4.0]
   * // [1.0, 2.0, 3.0, 4.0]
   *
   * var v = [1.0, 1.0, 1.0, 1.0, 2.0, 2.0, 2.0, 2.0, 3.0, 3.0, 3.0, 3.0, 4.0, 4.0, 4.0, 4.0];
   * var m = Cesium.Matrix4.fromArray(v);
   *
   * // Create same Matrix4 with using an offset into an array
   * var v2 = [0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 2.0, 2.0, 2.0, 2.0, 3.0, 3.0, 3.0, 3.0, 4.0, 4.0, 4.0, 4.0];
   * var m2 = Cesium.Matrix4.fromArray(v2, 2);
   */
  Matrix4.fromArray = Matrix4.unpack;

  /**
   * Computes a Matrix4 instance from a column-major order array.
   *
   * @param {Number[]} values The column-major order array.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   */
  Matrix4.fromColumnMajorArray = function (values, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("values", values);
    //>>includeEnd('debug');

    return Matrix4.clone(values, result);
  };

  /**
   * Computes a Matrix4 instance from a row-major order array.
   * The resulting matrix will be in column-major order.
   *
   * @param {Number[]} values The row-major order array.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   */
  Matrix4.fromRowMajorArray = function (values, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("values", values);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix4(
        values[0],
        values[1],
        values[2],
        values[3],
        values[4],
        values[5],
        values[6],
        values[7],
        values[8],
        values[9],
        values[10],
        values[11],
        values[12],
        values[13],
        values[14],
        values[15]
      );
    }
    result[0] = values[0];
    result[1] = values[4];
    result[2] = values[8];
    result[3] = values[12];
    result[4] = values[1];
    result[5] = values[5];
    result[6] = values[9];
    result[7] = values[13];
    result[8] = values[2];
    result[9] = values[6];
    result[10] = values[10];
    result[11] = values[14];
    result[12] = values[3];
    result[13] = values[7];
    result[14] = values[11];
    result[15] = values[15];
    return result;
  };

  /**
   * Computes a Matrix4 instance from a Matrix3 representing the rotation
   * and a Cartesian3 representing the translation.
   *
   * @param {Matrix3} rotation The upper left portion of the matrix representing the rotation.
   * @param {Cartesian3} [translation=Cartesian3.ZERO] The upper right portion of the matrix representing the translation.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   */
  Matrix4.fromRotationTranslation = function (rotation, translation, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rotation", rotation);
    //>>includeEnd('debug');

    translation = defaultValue(translation, Cartesian3.ZERO);

    if (!defined(result)) {
      return new Matrix4(
        rotation[0],
        rotation[3],
        rotation[6],
        translation.x,
        rotation[1],
        rotation[4],
        rotation[7],
        translation.y,
        rotation[2],
        rotation[5],
        rotation[8],
        translation.z,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }

    result[0] = rotation[0];
    result[1] = rotation[1];
    result[2] = rotation[2];
    result[3] = 0.0;
    result[4] = rotation[3];
    result[5] = rotation[4];
    result[6] = rotation[5];
    result[7] = 0.0;
    result[8] = rotation[6];
    result[9] = rotation[7];
    result[10] = rotation[8];
    result[11] = 0.0;
    result[12] = translation.x;
    result[13] = translation.y;
    result[14] = translation.z;
    result[15] = 1.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance from a translation, rotation, and scale (TRS)
   * representation with the rotation represented as a quaternion.
   *
   * @param {Cartesian3} translation The translation transformation.
   * @param {Quaternion} rotation The rotation transformation.
   * @param {Cartesian3} scale The non-uniform scale transformation.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   *
   * @example
   * var result = Cesium.Matrix4.fromTranslationQuaternionRotationScale(
   *   new Cesium.Cartesian3(1.0, 2.0, 3.0), // translation
   *   Cesium.Quaternion.IDENTITY,           // rotation
   *   new Cesium.Cartesian3(7.0, 8.0, 9.0), // scale
   *   result);
   */
  Matrix4.fromTranslationQuaternionRotationScale = function (
    translation,
    rotation,
    scale,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("translation", translation);
    Check.typeOf.object("rotation", rotation);
    Check.typeOf.object("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Matrix4();
    }

    var scaleX = scale.x;
    var scaleY = scale.y;
    var scaleZ = scale.z;

    var x2 = rotation.x * rotation.x;
    var xy = rotation.x * rotation.y;
    var xz = rotation.x * rotation.z;
    var xw = rotation.x * rotation.w;
    var y2 = rotation.y * rotation.y;
    var yz = rotation.y * rotation.z;
    var yw = rotation.y * rotation.w;
    var z2 = rotation.z * rotation.z;
    var zw = rotation.z * rotation.w;
    var w2 = rotation.w * rotation.w;

    var m00 = x2 - y2 - z2 + w2;
    var m01 = 2.0 * (xy - zw);
    var m02 = 2.0 * (xz + yw);

    var m10 = 2.0 * (xy + zw);
    var m11 = -x2 + y2 - z2 + w2;
    var m12 = 2.0 * (yz - xw);

    var m20 = 2.0 * (xz - yw);
    var m21 = 2.0 * (yz + xw);
    var m22 = -x2 - y2 + z2 + w2;

    result[0] = m00 * scaleX;
    result[1] = m10 * scaleX;
    result[2] = m20 * scaleX;
    result[3] = 0.0;
    result[4] = m01 * scaleY;
    result[5] = m11 * scaleY;
    result[6] = m21 * scaleY;
    result[7] = 0.0;
    result[8] = m02 * scaleZ;
    result[9] = m12 * scaleZ;
    result[10] = m22 * scaleZ;
    result[11] = 0.0;
    result[12] = translation.x;
    result[13] = translation.y;
    result[14] = translation.z;
    result[15] = 1.0;

    return result;
  };

  /**
   * Creates a Matrix4 instance from a {@link TranslationRotationScale} instance.
   *
   * @param {TranslationRotationScale} translationRotationScale The instance.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   */
  Matrix4.fromTranslationRotationScale = function (
    translationRotationScale,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("translationRotationScale", translationRotationScale);
    //>>includeEnd('debug');

    return Matrix4.fromTranslationQuaternionRotationScale(
      translationRotationScale.translation,
      translationRotationScale.rotation,
      translationRotationScale.scale,
      result
    );
  };

  /**
   * Creates a Matrix4 instance from a Cartesian3 representing the translation.
   *
   * @param {Cartesian3} translation The upper right portion of the matrix representing the translation.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   *
   * @see Matrix4.multiplyByTranslation
   */
  Matrix4.fromTranslation = function (translation, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("translation", translation);
    //>>includeEnd('debug');

    return Matrix4.fromRotationTranslation(Matrix3.IDENTITY, translation, result);
  };

  /**
   * Computes a Matrix4 instance representing a non-uniform scale.
   *
   * @param {Cartesian3} scale The x, y, and z scale factors.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [7.0, 0.0, 0.0, 0.0]
   * //   [0.0, 8.0, 0.0, 0.0]
   * //   [0.0, 0.0, 9.0, 0.0]
   * //   [0.0, 0.0, 0.0, 1.0]
   * var m = Cesium.Matrix4.fromScale(new Cesium.Cartesian3(7.0, 8.0, 9.0));
   */
  Matrix4.fromScale = function (scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix4(
        scale.x,
        0.0,
        0.0,
        0.0,
        0.0,
        scale.y,
        0.0,
        0.0,
        0.0,
        0.0,
        scale.z,
        0.0,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }

    result[0] = scale.x;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = scale.y;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 0.0;
    result[9] = 0.0;
    result[10] = scale.z;
    result[11] = 0.0;
    result[12] = 0.0;
    result[13] = 0.0;
    result[14] = 0.0;
    result[15] = 1.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance representing a uniform scale.
   *
   * @param {Number} scale The uniform scale factor.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [2.0, 0.0, 0.0, 0.0]
   * //   [0.0, 2.0, 0.0, 0.0]
   * //   [0.0, 0.0, 2.0, 0.0]
   * //   [0.0, 0.0, 0.0, 1.0]
   * var m = Cesium.Matrix4.fromUniformScale(2.0);
   */
  Matrix4.fromUniformScale = function (scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix4(
        scale,
        0.0,
        0.0,
        0.0,
        0.0,
        scale,
        0.0,
        0.0,
        0.0,
        0.0,
        scale,
        0.0,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }

    result[0] = scale;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = scale;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 0.0;
    result[9] = 0.0;
    result[10] = scale;
    result[11] = 0.0;
    result[12] = 0.0;
    result[13] = 0.0;
    result[14] = 0.0;
    result[15] = 1.0;
    return result;
  };

  var fromCameraF = new Cartesian3();
  var fromCameraR = new Cartesian3();
  var fromCameraU = new Cartesian3();

  /**
   * Computes a Matrix4 instance from a Camera.
   *
   * @param {Camera} camera The camera to use.
   * @param {Matrix4} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix4} The modified result parameter, or a new Matrix4 instance if one was not provided.
   */
  Matrix4.fromCamera = function (camera, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("camera", camera);
    //>>includeEnd('debug');

    var position = camera.position;
    var direction = camera.direction;
    var up = camera.up;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("camera.position", position);
    Check.typeOf.object("camera.direction", direction);
    Check.typeOf.object("camera.up", up);
    //>>includeEnd('debug');

    Cartesian3.normalize(direction, fromCameraF);
    Cartesian3.normalize(
      Cartesian3.cross(fromCameraF, up, fromCameraR),
      fromCameraR
    );
    Cartesian3.normalize(
      Cartesian3.cross(fromCameraR, fromCameraF, fromCameraU),
      fromCameraU
    );

    var sX = fromCameraR.x;
    var sY = fromCameraR.y;
    var sZ = fromCameraR.z;
    var fX = fromCameraF.x;
    var fY = fromCameraF.y;
    var fZ = fromCameraF.z;
    var uX = fromCameraU.x;
    var uY = fromCameraU.y;
    var uZ = fromCameraU.z;
    var positionX = position.x;
    var positionY = position.y;
    var positionZ = position.z;
    var t0 = sX * -positionX + sY * -positionY + sZ * -positionZ;
    var t1 = uX * -positionX + uY * -positionY + uZ * -positionZ;
    var t2 = fX * positionX + fY * positionY + fZ * positionZ;

    // The code below this comment is an optimized
    // version of the commented lines.
    // Rather that create two matrices and then multiply,
    // we just bake in the multiplcation as part of creation.
    // var rotation = new Matrix4(
    //                 sX,  sY,  sZ, 0.0,
    //                 uX,  uY,  uZ, 0.0,
    //                -fX, -fY, -fZ, 0.0,
    //                 0.0,  0.0,  0.0, 1.0);
    // var translation = new Matrix4(
    //                 1.0, 0.0, 0.0, -position.x,
    //                 0.0, 1.0, 0.0, -position.y,
    //                 0.0, 0.0, 1.0, -position.z,
    //                 0.0, 0.0, 0.0, 1.0);
    // return rotation.multiply(translation);
    if (!defined(result)) {
      return new Matrix4(
        sX,
        sY,
        sZ,
        t0,
        uX,
        uY,
        uZ,
        t1,
        -fX,
        -fY,
        -fZ,
        t2,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }
    result[0] = sX;
    result[1] = uX;
    result[2] = -fX;
    result[3] = 0.0;
    result[4] = sY;
    result[5] = uY;
    result[6] = -fY;
    result[7] = 0.0;
    result[8] = sZ;
    result[9] = uZ;
    result[10] = -fZ;
    result[11] = 0.0;
    result[12] = t0;
    result[13] = t1;
    result[14] = t2;
    result[15] = 1.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance representing a perspective transformation matrix.
   *
   * @param {Number} fovY The field of view along the Y axis in radians.
   * @param {Number} aspectRatio The aspect ratio.
   * @param {Number} near The distance to the near plane in meters.
   * @param {Number} far The distance to the far plane in meters.
   * @param {Matrix4} result The object in which the result will be stored.
   * @returns {Matrix4} The modified result parameter.
   *
   * @exception {DeveloperError} fovY must be in (0, PI].
   * @exception {DeveloperError} aspectRatio must be greater than zero.
   * @exception {DeveloperError} near must be greater than zero.
   * @exception {DeveloperError} far must be greater than zero.
   */
  Matrix4.computePerspectiveFieldOfView = function (
    fovY,
    aspectRatio,
    near,
    far,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThan("fovY", fovY, 0.0);
    Check.typeOf.number.lessThan("fovY", fovY, Math.PI);
    Check.typeOf.number.greaterThan("near", near, 0.0);
    Check.typeOf.number.greaterThan("far", far, 0.0);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var bottom = Math.tan(fovY * 0.5);

    var column1Row1 = 1.0 / bottom;
    var column0Row0 = column1Row1 / aspectRatio;
    var column2Row2 = (far + near) / (near - far);
    var column3Row2 = (2.0 * far * near) / (near - far);

    result[0] = column0Row0;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = column1Row1;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 0.0;
    result[9] = 0.0;
    result[10] = column2Row2;
    result[11] = -1.0;
    result[12] = 0.0;
    result[13] = 0.0;
    result[14] = column3Row2;
    result[15] = 0.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance representing an orthographic transformation matrix.
   *
   * @param {Number} left The number of meters to the left of the camera that will be in view.
   * @param {Number} right The number of meters to the right of the camera that will be in view.
   * @param {Number} bottom The number of meters below of the camera that will be in view.
   * @param {Number} top The number of meters above of the camera that will be in view.
   * @param {Number} near The distance to the near plane in meters.
   * @param {Number} far The distance to the far plane in meters.
   * @param {Matrix4} result The object in which the result will be stored.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.computeOrthographicOffCenter = function (
    left,
    right,
    bottom,
    top,
    near,
    far,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("left", left);
    Check.typeOf.number("right", right);
    Check.typeOf.number("bottom", bottom);
    Check.typeOf.number("top", top);
    Check.typeOf.number("near", near);
    Check.typeOf.number("far", far);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var a = 1.0 / (right - left);
    var b = 1.0 / (top - bottom);
    var c = 1.0 / (far - near);

    var tx = -(right + left) * a;
    var ty = -(top + bottom) * b;
    var tz = -(far + near) * c;
    a *= 2.0;
    b *= 2.0;
    c *= -2.0;

    result[0] = a;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = b;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 0.0;
    result[9] = 0.0;
    result[10] = c;
    result[11] = 0.0;
    result[12] = tx;
    result[13] = ty;
    result[14] = tz;
    result[15] = 1.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance representing an off center perspective transformation.
   *
   * @param {Number} left The number of meters to the left of the camera that will be in view.
   * @param {Number} right The number of meters to the right of the camera that will be in view.
   * @param {Number} bottom The number of meters below of the camera that will be in view.
   * @param {Number} top The number of meters above of the camera that will be in view.
   * @param {Number} near The distance to the near plane in meters.
   * @param {Number} far The distance to the far plane in meters.
   * @param {Matrix4} result The object in which the result will be stored.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.computePerspectiveOffCenter = function (
    left,
    right,
    bottom,
    top,
    near,
    far,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("left", left);
    Check.typeOf.number("right", right);
    Check.typeOf.number("bottom", bottom);
    Check.typeOf.number("top", top);
    Check.typeOf.number("near", near);
    Check.typeOf.number("far", far);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var column0Row0 = (2.0 * near) / (right - left);
    var column1Row1 = (2.0 * near) / (top - bottom);
    var column2Row0 = (right + left) / (right - left);
    var column2Row1 = (top + bottom) / (top - bottom);
    var column2Row2 = -(far + near) / (far - near);
    var column2Row3 = -1.0;
    var column3Row2 = (-2.0 * far * near) / (far - near);

    result[0] = column0Row0;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = column1Row1;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = column2Row0;
    result[9] = column2Row1;
    result[10] = column2Row2;
    result[11] = column2Row3;
    result[12] = 0.0;
    result[13] = 0.0;
    result[14] = column3Row2;
    result[15] = 0.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance representing an infinite off center perspective transformation.
   *
   * @param {Number} left The number of meters to the left of the camera that will be in view.
   * @param {Number} right The number of meters to the right of the camera that will be in view.
   * @param {Number} bottom The number of meters below of the camera that will be in view.
   * @param {Number} top The number of meters above of the camera that will be in view.
   * @param {Number} near The distance to the near plane in meters.
   * @param {Matrix4} result The object in which the result will be stored.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.computeInfinitePerspectiveOffCenter = function (
    left,
    right,
    bottom,
    top,
    near,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("left", left);
    Check.typeOf.number("right", right);
    Check.typeOf.number("bottom", bottom);
    Check.typeOf.number("top", top);
    Check.typeOf.number("near", near);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var column0Row0 = (2.0 * near) / (right - left);
    var column1Row1 = (2.0 * near) / (top - bottom);
    var column2Row0 = (right + left) / (right - left);
    var column2Row1 = (top + bottom) / (top - bottom);
    var column2Row2 = -1.0;
    var column2Row3 = -1.0;
    var column3Row2 = -2.0 * near;

    result[0] = column0Row0;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = column1Row1;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = column2Row0;
    result[9] = column2Row1;
    result[10] = column2Row2;
    result[11] = column2Row3;
    result[12] = 0.0;
    result[13] = 0.0;
    result[14] = column3Row2;
    result[15] = 0.0;
    return result;
  };

  /**
   * Computes a Matrix4 instance that transforms from normalized device coordinates to window coordinates.
   *
   * @param {Object} [viewport = { x : 0.0, y : 0.0, width : 0.0, height : 0.0 }] The viewport's corners as shown in Example 1.
   * @param {Number} [nearDepthRange=0.0] The near plane distance in window coordinates.
   * @param {Number} [farDepthRange=1.0] The far plane distance in window coordinates.
   * @param {Matrix4} [result] The object in which the result will be stored.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * // Create viewport transformation using an explicit viewport and depth range.
   * var m = Cesium.Matrix4.computeViewportTransformation({
   *     x : 0.0,
   *     y : 0.0,
   *     width : 1024.0,
   *     height : 768.0
   * }, 0.0, 1.0, new Cesium.Matrix4());
   */
  Matrix4.computeViewportTransformation = function (
    viewport,
    nearDepthRange,
    farDepthRange,
    result
  ) {
    if (!defined(result)) {
      result = new Matrix4();
    }

    viewport = defaultValue(viewport, defaultValue.EMPTY_OBJECT);
    var x = defaultValue(viewport.x, 0.0);
    var y = defaultValue(viewport.y, 0.0);
    var width = defaultValue(viewport.width, 0.0);
    var height = defaultValue(viewport.height, 0.0);
    nearDepthRange = defaultValue(nearDepthRange, 0.0);
    farDepthRange = defaultValue(farDepthRange, 1.0);

    var halfWidth = width * 0.5;
    var halfHeight = height * 0.5;
    var halfDepth = (farDepthRange - nearDepthRange) * 0.5;

    var column0Row0 = halfWidth;
    var column1Row1 = halfHeight;
    var column2Row2 = halfDepth;
    var column3Row0 = x + halfWidth;
    var column3Row1 = y + halfHeight;
    var column3Row2 = nearDepthRange + halfDepth;
    var column3Row3 = 1.0;

    result[0] = column0Row0;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = 0.0;
    result[4] = 0.0;
    result[5] = column1Row1;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 0.0;
    result[9] = 0.0;
    result[10] = column2Row2;
    result[11] = 0.0;
    result[12] = column3Row0;
    result[13] = column3Row1;
    result[14] = column3Row2;
    result[15] = column3Row3;
    return result;
  };

  /**
   * Computes a Matrix4 instance that transforms from world space to view space.
   *
   * @param {Cartesian3} position The position of the camera.
   * @param {Cartesian3} direction The forward direction.
   * @param {Cartesian3} up The up direction.
   * @param {Cartesian3} right The right direction.
   * @param {Matrix4} result The object in which the result will be stored.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.computeView = function (position, direction, up, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("position", position);
    Check.typeOf.object("direction", direction);
    Check.typeOf.object("up", up);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = right.x;
    result[1] = up.x;
    result[2] = -direction.x;
    result[3] = 0.0;
    result[4] = right.y;
    result[5] = up.y;
    result[6] = -direction.y;
    result[7] = 0.0;
    result[8] = right.z;
    result[9] = up.z;
    result[10] = -direction.z;
    result[11] = 0.0;
    result[12] = -Cartesian3.dot(right, position);
    result[13] = -Cartesian3.dot(up, position);
    result[14] = Cartesian3.dot(direction, position);
    result[15] = 1.0;
    return result;
  };

  /**
   * Computes an Array from the provided Matrix4 instance.
   * The array will be in column-major order.
   *
   * @param {Matrix4} matrix The matrix to use..
   * @param {Number[]} [result] The Array onto which to store the result.
   * @returns {Number[]} The modified Array parameter or a new Array instance if one was not provided.
   *
   * @example
   * //create an array from an instance of Matrix4
   * // m = [10.0, 14.0, 18.0, 22.0]
   * //     [11.0, 15.0, 19.0, 23.0]
   * //     [12.0, 16.0, 20.0, 24.0]
   * //     [13.0, 17.0, 21.0, 25.0]
   * var a = Cesium.Matrix4.toArray(m);
   *
   * // m remains the same
   * //creates a = [10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0]
   */
  Matrix4.toArray = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return [
        matrix[0],
        matrix[1],
        matrix[2],
        matrix[3],
        matrix[4],
        matrix[5],
        matrix[6],
        matrix[7],
        matrix[8],
        matrix[9],
        matrix[10],
        matrix[11],
        matrix[12],
        matrix[13],
        matrix[14],
        matrix[15],
      ];
    }
    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    result[4] = matrix[4];
    result[5] = matrix[5];
    result[6] = matrix[6];
    result[7] = matrix[7];
    result[8] = matrix[8];
    result[9] = matrix[9];
    result[10] = matrix[10];
    result[11] = matrix[11];
    result[12] = matrix[12];
    result[13] = matrix[13];
    result[14] = matrix[14];
    result[15] = matrix[15];
    return result;
  };

  /**
   * Computes the array index of the element at the provided row and column.
   *
   * @param {Number} row The zero-based index of the row.
   * @param {Number} column The zero-based index of the column.
   * @returns {Number} The index of the element at the provided row and column.
   *
   * @exception {DeveloperError} row must be 0, 1, 2, or 3.
   * @exception {DeveloperError} column must be 0, 1, 2, or 3.
   *
   * @example
   * var myMatrix = new Cesium.Matrix4();
   * var column1Row0Index = Cesium.Matrix4.getElementIndex(1, 0);
   * var column1Row0 = myMatrix[column1Row0Index];
   * myMatrix[column1Row0Index] = 10.0;
   */
  Matrix4.getElementIndex = function (column, row) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("row", row, 0);
    Check.typeOf.number.lessThanOrEquals("row", row, 3);

    Check.typeOf.number.greaterThanOrEquals("column", column, 0);
    Check.typeOf.number.lessThanOrEquals("column", column, 3);
    //>>includeEnd('debug');

    return column * 4 + row;
  };

  /**
   * Retrieves a copy of the matrix column at the provided index as a Cartesian4 instance.
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Number} index The zero-based index of the column to retrieve.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, 2, or 3.
   *
   * @example
   * //returns a Cartesian4 instance with values from the specified column
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * //Example 1: Creates an instance of Cartesian
   * var a = Cesium.Matrix4.getColumn(m, 2, new Cesium.Cartesian4());
   *
   * @example
   * //Example 2: Sets values for Cartesian instance
   * var a = new Cesium.Cartesian4();
   * Cesium.Matrix4.getColumn(m, 2, a);
   *
   * // a.x = 12.0; a.y = 16.0; a.z = 20.0; a.w = 24.0;
   */
  Matrix4.getColumn = function (matrix, index, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 3);

    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var startIndex = index * 4;
    var x = matrix[startIndex];
    var y = matrix[startIndex + 1];
    var z = matrix[startIndex + 2];
    var w = matrix[startIndex + 3];

    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  /**
   * Computes a new matrix that replaces the specified column in the provided matrix with the provided Cartesian4 instance.
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Number} index The zero-based index of the column to set.
   * @param {Cartesian4} cartesian The Cartesian whose values will be assigned to the specified column.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, 2, or 3.
   *
   * @example
   * //creates a new Matrix4 instance with new column values from the Cartesian4 instance
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * var a = Cesium.Matrix4.setColumn(m, 2, new Cesium.Cartesian4(99.0, 98.0, 97.0, 96.0), new Cesium.Matrix4());
   *
   * // m remains the same
   * // a = [10.0, 11.0, 99.0, 13.0]
   * //     [14.0, 15.0, 98.0, 17.0]
   * //     [18.0, 19.0, 97.0, 21.0]
   * //     [22.0, 23.0, 96.0, 25.0]
   */
  Matrix4.setColumn = function (matrix, index, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 3);

    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result = Matrix4.clone(matrix, result);
    var startIndex = index * 4;
    result[startIndex] = cartesian.x;
    result[startIndex + 1] = cartesian.y;
    result[startIndex + 2] = cartesian.z;
    result[startIndex + 3] = cartesian.w;
    return result;
  };

  /**
   * Computes a new matrix that replaces the translation in the rightmost column of the provided
   * matrix with the provided translation.  This assumes the matrix is an affine transformation
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Cartesian3} translation The translation that replaces the translation of the provided matrix.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.setTranslation = function (matrix, translation, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("translation", translation);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];

    result[4] = matrix[4];
    result[5] = matrix[5];
    result[6] = matrix[6];
    result[7] = matrix[7];

    result[8] = matrix[8];
    result[9] = matrix[9];
    result[10] = matrix[10];
    result[11] = matrix[11];

    result[12] = translation.x;
    result[13] = translation.y;
    result[14] = translation.z;
    result[15] = matrix[15];

    return result;
  };

  var scaleScratch = new Cartesian3();
  /**
   * Computes a new matrix that replaces the scale with the provided scale.  This assumes the matrix is an affine transformation
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Cartesian3} scale The scale that replaces the scale of the provided matrix.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.setScale = function (matrix, scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("scale", scale);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var existingScale = Matrix4.getScale(matrix, scaleScratch);
    var newScale = Cartesian3.divideComponents(
      scale,
      existingScale,
      scaleScratch
    );
    return Matrix4.multiplyByScale(matrix, newScale, result);
  };

  /**
   * Retrieves a copy of the matrix row at the provided index as a Cartesian4 instance.
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Number} index The zero-based index of the row to retrieve.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, 2, or 3.
   *
   * @example
   * //returns a Cartesian4 instance with values from the specified column
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * //Example 1: Returns an instance of Cartesian
   * var a = Cesium.Matrix4.getRow(m, 2, new Cesium.Cartesian4());
   *
   * @example
   * //Example 2: Sets values for a Cartesian instance
   * var a = new Cesium.Cartesian4();
   * Cesium.Matrix4.getRow(m, 2, a);
   *
   * // a.x = 18.0; a.y = 19.0; a.z = 20.0; a.w = 21.0;
   */
  Matrix4.getRow = function (matrix, index, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 3);

    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var x = matrix[index];
    var y = matrix[index + 4];
    var z = matrix[index + 8];
    var w = matrix[index + 12];

    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  /**
   * Computes a new matrix that replaces the specified row in the provided matrix with the provided Cartesian4 instance.
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Number} index The zero-based index of the row to set.
   * @param {Cartesian4} cartesian The Cartesian whose values will be assigned to the specified row.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0, 1, 2, or 3.
   *
   * @example
   * //create a new Matrix4 instance with new row values from the Cartesian4 instance
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * var a = Cesium.Matrix4.setRow(m, 2, new Cesium.Cartesian4(99.0, 98.0, 97.0, 96.0), new Cesium.Matrix4());
   *
   * // m remains the same
   * // a = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [99.0, 98.0, 97.0, 96.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   */
  Matrix4.setRow = function (matrix, index, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 3);

    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result = Matrix4.clone(matrix, result);
    result[index] = cartesian.x;
    result[index + 4] = cartesian.y;
    result[index + 8] = cartesian.z;
    result[index + 12] = cartesian.w;
    return result;
  };

  var scratchColumn$1 = new Cartesian3();

  /**
   * Extracts the non-uniform scale assuming the matrix is an affine transformation.
   *
   * @param {Matrix4} matrix The matrix.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter
   */
  Matrix4.getScale = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Cartesian3.magnitude(
      Cartesian3.fromElements(matrix[0], matrix[1], matrix[2], scratchColumn$1)
    );
    result.y = Cartesian3.magnitude(
      Cartesian3.fromElements(matrix[4], matrix[5], matrix[6], scratchColumn$1)
    );
    result.z = Cartesian3.magnitude(
      Cartesian3.fromElements(matrix[8], matrix[9], matrix[10], scratchColumn$1)
    );
    return result;
  };

  var scratchScale$1 = new Cartesian3();

  /**
   * Computes the maximum scale assuming the matrix is an affine transformation.
   * The maximum scale is the maximum length of the column vectors in the upper-left
   * 3x3 matrix.
   *
   * @param {Matrix4} matrix The matrix.
   * @returns {Number} The maximum scale.
   */
  Matrix4.getMaximumScale = function (matrix) {
    Matrix4.getScale(matrix, scratchScale$1);
    return Cartesian3.maximumComponent(scratchScale$1);
  };

  /**
   * Computes the product of two matrices.
   *
   * @param {Matrix4} left The first matrix.
   * @param {Matrix4} right The second matrix.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.multiply = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var left0 = left[0];
    var left1 = left[1];
    var left2 = left[2];
    var left3 = left[3];
    var left4 = left[4];
    var left5 = left[5];
    var left6 = left[6];
    var left7 = left[7];
    var left8 = left[8];
    var left9 = left[9];
    var left10 = left[10];
    var left11 = left[11];
    var left12 = left[12];
    var left13 = left[13];
    var left14 = left[14];
    var left15 = left[15];

    var right0 = right[0];
    var right1 = right[1];
    var right2 = right[2];
    var right3 = right[3];
    var right4 = right[4];
    var right5 = right[5];
    var right6 = right[6];
    var right7 = right[7];
    var right8 = right[8];
    var right9 = right[9];
    var right10 = right[10];
    var right11 = right[11];
    var right12 = right[12];
    var right13 = right[13];
    var right14 = right[14];
    var right15 = right[15];

    var column0Row0 =
      left0 * right0 + left4 * right1 + left8 * right2 + left12 * right3;
    var column0Row1 =
      left1 * right0 + left5 * right1 + left9 * right2 + left13 * right3;
    var column0Row2 =
      left2 * right0 + left6 * right1 + left10 * right2 + left14 * right3;
    var column0Row3 =
      left3 * right0 + left7 * right1 + left11 * right2 + left15 * right3;

    var column1Row0 =
      left0 * right4 + left4 * right5 + left8 * right6 + left12 * right7;
    var column1Row1 =
      left1 * right4 + left5 * right5 + left9 * right6 + left13 * right7;
    var column1Row2 =
      left2 * right4 + left6 * right5 + left10 * right6 + left14 * right7;
    var column1Row3 =
      left3 * right4 + left7 * right5 + left11 * right6 + left15 * right7;

    var column2Row0 =
      left0 * right8 + left4 * right9 + left8 * right10 + left12 * right11;
    var column2Row1 =
      left1 * right8 + left5 * right9 + left9 * right10 + left13 * right11;
    var column2Row2 =
      left2 * right8 + left6 * right9 + left10 * right10 + left14 * right11;
    var column2Row3 =
      left3 * right8 + left7 * right9 + left11 * right10 + left15 * right11;

    var column3Row0 =
      left0 * right12 + left4 * right13 + left8 * right14 + left12 * right15;
    var column3Row1 =
      left1 * right12 + left5 * right13 + left9 * right14 + left13 * right15;
    var column3Row2 =
      left2 * right12 + left6 * right13 + left10 * right14 + left14 * right15;
    var column3Row3 =
      left3 * right12 + left7 * right13 + left11 * right14 + left15 * right15;

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column0Row2;
    result[3] = column0Row3;
    result[4] = column1Row0;
    result[5] = column1Row1;
    result[6] = column1Row2;
    result[7] = column1Row3;
    result[8] = column2Row0;
    result[9] = column2Row1;
    result[10] = column2Row2;
    result[11] = column2Row3;
    result[12] = column3Row0;
    result[13] = column3Row1;
    result[14] = column3Row2;
    result[15] = column3Row3;
    return result;
  };

  /**
   * Computes the sum of two matrices.
   *
   * @param {Matrix4} left The first matrix.
   * @param {Matrix4} right The second matrix.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = left[0] + right[0];
    result[1] = left[1] + right[1];
    result[2] = left[2] + right[2];
    result[3] = left[3] + right[3];
    result[4] = left[4] + right[4];
    result[5] = left[5] + right[5];
    result[6] = left[6] + right[6];
    result[7] = left[7] + right[7];
    result[8] = left[8] + right[8];
    result[9] = left[9] + right[9];
    result[10] = left[10] + right[10];
    result[11] = left[11] + right[11];
    result[12] = left[12] + right[12];
    result[13] = left[13] + right[13];
    result[14] = left[14] + right[14];
    result[15] = left[15] + right[15];
    return result;
  };

  /**
   * Computes the difference of two matrices.
   *
   * @param {Matrix4} left The first matrix.
   * @param {Matrix4} right The second matrix.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = left[0] - right[0];
    result[1] = left[1] - right[1];
    result[2] = left[2] - right[2];
    result[3] = left[3] - right[3];
    result[4] = left[4] - right[4];
    result[5] = left[5] - right[5];
    result[6] = left[6] - right[6];
    result[7] = left[7] - right[7];
    result[8] = left[8] - right[8];
    result[9] = left[9] - right[9];
    result[10] = left[10] - right[10];
    result[11] = left[11] - right[11];
    result[12] = left[12] - right[12];
    result[13] = left[13] - right[13];
    result[14] = left[14] - right[14];
    result[15] = left[15] - right[15];
    return result;
  };

  /**
   * Computes the product of two matrices assuming the matrices are
   * affine transformation matrices, where the upper left 3x3 elements
   * are a rotation matrix, and the upper three elements in the fourth
   * column are the translation.  The bottom row is assumed to be [0, 0, 0, 1].
   * The matrix is not verified to be in the proper form.
   * This method is faster than computing the product for general 4x4
   * matrices using {@link Matrix4.multiply}.
   *
   * @param {Matrix4} left The first matrix.
   * @param {Matrix4} right The second matrix.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * var m1 = new Cesium.Matrix4(1.0, 6.0, 7.0, 0.0, 2.0, 5.0, 8.0, 0.0, 3.0, 4.0, 9.0, 0.0, 0.0, 0.0, 0.0, 1.0);
   * var m2 = Cesium.Transforms.eastNorthUpToFixedFrame(new Cesium.Cartesian3(1.0, 1.0, 1.0));
   * var m3 = Cesium.Matrix4.multiplyTransformation(m1, m2, new Cesium.Matrix4());
   */
  Matrix4.multiplyTransformation = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var left0 = left[0];
    var left1 = left[1];
    var left2 = left[2];
    var left4 = left[4];
    var left5 = left[5];
    var left6 = left[6];
    var left8 = left[8];
    var left9 = left[9];
    var left10 = left[10];
    var left12 = left[12];
    var left13 = left[13];
    var left14 = left[14];

    var right0 = right[0];
    var right1 = right[1];
    var right2 = right[2];
    var right4 = right[4];
    var right5 = right[5];
    var right6 = right[6];
    var right8 = right[8];
    var right9 = right[9];
    var right10 = right[10];
    var right12 = right[12];
    var right13 = right[13];
    var right14 = right[14];

    var column0Row0 = left0 * right0 + left4 * right1 + left8 * right2;
    var column0Row1 = left1 * right0 + left5 * right1 + left9 * right2;
    var column0Row2 = left2 * right0 + left6 * right1 + left10 * right2;

    var column1Row0 = left0 * right4 + left4 * right5 + left8 * right6;
    var column1Row1 = left1 * right4 + left5 * right5 + left9 * right6;
    var column1Row2 = left2 * right4 + left6 * right5 + left10 * right6;

    var column2Row0 = left0 * right8 + left4 * right9 + left8 * right10;
    var column2Row1 = left1 * right8 + left5 * right9 + left9 * right10;
    var column2Row2 = left2 * right8 + left6 * right9 + left10 * right10;

    var column3Row0 =
      left0 * right12 + left4 * right13 + left8 * right14 + left12;
    var column3Row1 =
      left1 * right12 + left5 * right13 + left9 * right14 + left13;
    var column3Row2 =
      left2 * right12 + left6 * right13 + left10 * right14 + left14;

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column0Row2;
    result[3] = 0.0;
    result[4] = column1Row0;
    result[5] = column1Row1;
    result[6] = column1Row2;
    result[7] = 0.0;
    result[8] = column2Row0;
    result[9] = column2Row1;
    result[10] = column2Row2;
    result[11] = 0.0;
    result[12] = column3Row0;
    result[13] = column3Row1;
    result[14] = column3Row2;
    result[15] = 1.0;
    return result;
  };

  /**
   * Multiplies a transformation matrix (with a bottom row of <code>[0.0, 0.0, 0.0, 1.0]</code>)
   * by a 3x3 rotation matrix.  This is an optimization
   * for <code>Matrix4.multiply(m, Matrix4.fromRotationTranslation(rotation), m);</code> with less allocations and arithmetic operations.
   *
   * @param {Matrix4} matrix The matrix on the left-hand side.
   * @param {Matrix3} rotation The 3x3 rotation matrix on the right-hand side.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * // Instead of Cesium.Matrix4.multiply(m, Cesium.Matrix4.fromRotationTranslation(rotation), m);
   * Cesium.Matrix4.multiplyByMatrix3(m, rotation, m);
   */
  Matrix4.multiplyByMatrix3 = function (matrix, rotation, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("rotation", rotation);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var left0 = matrix[0];
    var left1 = matrix[1];
    var left2 = matrix[2];
    var left4 = matrix[4];
    var left5 = matrix[5];
    var left6 = matrix[6];
    var left8 = matrix[8];
    var left9 = matrix[9];
    var left10 = matrix[10];

    var right0 = rotation[0];
    var right1 = rotation[1];
    var right2 = rotation[2];
    var right4 = rotation[3];
    var right5 = rotation[4];
    var right6 = rotation[5];
    var right8 = rotation[6];
    var right9 = rotation[7];
    var right10 = rotation[8];

    var column0Row0 = left0 * right0 + left4 * right1 + left8 * right2;
    var column0Row1 = left1 * right0 + left5 * right1 + left9 * right2;
    var column0Row2 = left2 * right0 + left6 * right1 + left10 * right2;

    var column1Row0 = left0 * right4 + left4 * right5 + left8 * right6;
    var column1Row1 = left1 * right4 + left5 * right5 + left9 * right6;
    var column1Row2 = left2 * right4 + left6 * right5 + left10 * right6;

    var column2Row0 = left0 * right8 + left4 * right9 + left8 * right10;
    var column2Row1 = left1 * right8 + left5 * right9 + left9 * right10;
    var column2Row2 = left2 * right8 + left6 * right9 + left10 * right10;

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column0Row2;
    result[3] = 0.0;
    result[4] = column1Row0;
    result[5] = column1Row1;
    result[6] = column1Row2;
    result[7] = 0.0;
    result[8] = column2Row0;
    result[9] = column2Row1;
    result[10] = column2Row2;
    result[11] = 0.0;
    result[12] = matrix[12];
    result[13] = matrix[13];
    result[14] = matrix[14];
    result[15] = matrix[15];
    return result;
  };

  /**
   * Multiplies a transformation matrix (with a bottom row of <code>[0.0, 0.0, 0.0, 1.0]</code>)
   * by an implicit translation matrix defined by a {@link Cartesian3}.  This is an optimization
   * for <code>Matrix4.multiply(m, Matrix4.fromTranslation(position), m);</code> with less allocations and arithmetic operations.
   *
   * @param {Matrix4} matrix The matrix on the left-hand side.
   * @param {Cartesian3} translation The translation on the right-hand side.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * // Instead of Cesium.Matrix4.multiply(m, Cesium.Matrix4.fromTranslation(position), m);
   * Cesium.Matrix4.multiplyByTranslation(m, position, m);
   */
  Matrix4.multiplyByTranslation = function (matrix, translation, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("translation", translation);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var x = translation.x;
    var y = translation.y;
    var z = translation.z;

    var tx = x * matrix[0] + y * matrix[4] + z * matrix[8] + matrix[12];
    var ty = x * matrix[1] + y * matrix[5] + z * matrix[9] + matrix[13];
    var tz = x * matrix[2] + y * matrix[6] + z * matrix[10] + matrix[14];

    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    result[4] = matrix[4];
    result[5] = matrix[5];
    result[6] = matrix[6];
    result[7] = matrix[7];
    result[8] = matrix[8];
    result[9] = matrix[9];
    result[10] = matrix[10];
    result[11] = matrix[11];
    result[12] = tx;
    result[13] = ty;
    result[14] = tz;
    result[15] = matrix[15];
    return result;
  };

  var uniformScaleScratch = new Cartesian3();

  /**
   * Multiplies an affine transformation matrix (with a bottom row of <code>[0.0, 0.0, 0.0, 1.0]</code>)
   * by an implicit uniform scale matrix.  This is an optimization
   * for <code>Matrix4.multiply(m, Matrix4.fromUniformScale(scale), m);</code>, where
   * <code>m</code> must be an affine matrix.
   * This function performs fewer allocations and arithmetic operations.
   *
   * @param {Matrix4} matrix The affine matrix on the left-hand side.
   * @param {Number} scale The uniform scale on the right-hand side.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   *
   * @example
   * // Instead of Cesium.Matrix4.multiply(m, Cesium.Matrix4.fromUniformScale(scale), m);
   * Cesium.Matrix4.multiplyByUniformScale(m, scale, m);
   *
   * @see Matrix4.fromUniformScale
   * @see Matrix4.multiplyByScale
   */
  Matrix4.multiplyByUniformScale = function (matrix, scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number("scale", scale);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    uniformScaleScratch.x = scale;
    uniformScaleScratch.y = scale;
    uniformScaleScratch.z = scale;
    return Matrix4.multiplyByScale(matrix, uniformScaleScratch, result);
  };

  /**
   * Multiplies an affine transformation matrix (with a bottom row of <code>[0.0, 0.0, 0.0, 1.0]</code>)
   * by an implicit non-uniform scale matrix.  This is an optimization
   * for <code>Matrix4.multiply(m, Matrix4.fromUniformScale(scale), m);</code>, where
   * <code>m</code> must be an affine matrix.
   * This function performs fewer allocations and arithmetic operations.
   *
   * @param {Matrix4} matrix The affine matrix on the left-hand side.
   * @param {Cartesian3} scale The non-uniform scale on the right-hand side.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   *
   * @example
   * // Instead of Cesium.Matrix4.multiply(m, Cesium.Matrix4.fromScale(scale), m);
   * Cesium.Matrix4.multiplyByScale(m, scale, m);
   *
   * @see Matrix4.fromScale
   * @see Matrix4.multiplyByUniformScale
   */
  Matrix4.multiplyByScale = function (matrix, scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("scale", scale);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var scaleX = scale.x;
    var scaleY = scale.y;
    var scaleZ = scale.z;

    // Faster than Cartesian3.equals
    if (scaleX === 1.0 && scaleY === 1.0 && scaleZ === 1.0) {
      return Matrix4.clone(matrix, result);
    }

    result[0] = scaleX * matrix[0];
    result[1] = scaleX * matrix[1];
    result[2] = scaleX * matrix[2];
    result[3] = 0.0;
    result[4] = scaleY * matrix[4];
    result[5] = scaleY * matrix[5];
    result[6] = scaleY * matrix[6];
    result[7] = 0.0;
    result[8] = scaleZ * matrix[8];
    result[9] = scaleZ * matrix[9];
    result[10] = scaleZ * matrix[10];
    result[11] = 0.0;
    result[12] = matrix[12];
    result[13] = matrix[13];
    result[14] = matrix[14];
    result[15] = 1.0;
    return result;
  };

  /**
   * Computes the product of a matrix and a column vector.
   *
   * @param {Matrix4} matrix The matrix.
   * @param {Cartesian4} cartesian The vector.
   * @param {Cartesian4} result The object onto which to store the result.
   * @returns {Cartesian4} The modified result parameter.
   */
  Matrix4.multiplyByVector = function (matrix, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var vX = cartesian.x;
    var vY = cartesian.y;
    var vZ = cartesian.z;
    var vW = cartesian.w;

    var x = matrix[0] * vX + matrix[4] * vY + matrix[8] * vZ + matrix[12] * vW;
    var y = matrix[1] * vX + matrix[5] * vY + matrix[9] * vZ + matrix[13] * vW;
    var z = matrix[2] * vX + matrix[6] * vY + matrix[10] * vZ + matrix[14] * vW;
    var w = matrix[3] * vX + matrix[7] * vY + matrix[11] * vZ + matrix[15] * vW;

    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  /**
   * Computes the product of a matrix and a {@link Cartesian3}.  This is equivalent to calling {@link Matrix4.multiplyByVector}
   * with a {@link Cartesian4} with a <code>w</code> component of zero.
   *
   * @param {Matrix4} matrix The matrix.
   * @param {Cartesian3} cartesian The point.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   *
   * @example
   * var p = new Cesium.Cartesian3(1.0, 2.0, 3.0);
   * var result = Cesium.Matrix4.multiplyByPointAsVector(matrix, p, new Cesium.Cartesian3());
   * // A shortcut for
   * //   Cartesian3 p = ...
   * //   Cesium.Matrix4.multiplyByVector(matrix, new Cesium.Cartesian4(p.x, p.y, p.z, 0.0), result);
   */
  Matrix4.multiplyByPointAsVector = function (matrix, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var vX = cartesian.x;
    var vY = cartesian.y;
    var vZ = cartesian.z;

    var x = matrix[0] * vX + matrix[4] * vY + matrix[8] * vZ;
    var y = matrix[1] * vX + matrix[5] * vY + matrix[9] * vZ;
    var z = matrix[2] * vX + matrix[6] * vY + matrix[10] * vZ;

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Computes the product of a matrix and a {@link Cartesian3}. This is equivalent to calling {@link Matrix4.multiplyByVector}
   * with a {@link Cartesian4} with a <code>w</code> component of 1, but returns a {@link Cartesian3} instead of a {@link Cartesian4}.
   *
   * @param {Matrix4} matrix The matrix.
   * @param {Cartesian3} cartesian The point.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   *
   * @example
   * var p = new Cesium.Cartesian3(1.0, 2.0, 3.0);
   * var result = Cesium.Matrix4.multiplyByPoint(matrix, p, new Cesium.Cartesian3());
   */
  Matrix4.multiplyByPoint = function (matrix, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var vX = cartesian.x;
    var vY = cartesian.y;
    var vZ = cartesian.z;

    var x = matrix[0] * vX + matrix[4] * vY + matrix[8] * vZ + matrix[12];
    var y = matrix[1] * vX + matrix[5] * vY + matrix[9] * vZ + matrix[13];
    var z = matrix[2] * vX + matrix[6] * vY + matrix[10] * vZ + matrix[14];

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Computes the product of a matrix and a scalar.
   *
   * @param {Matrix4} matrix The matrix.
   * @param {Number} scalar The number to multiply by.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * //create a Matrix4 instance which is a scaled version of the supplied Matrix4
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * var a = Cesium.Matrix4.multiplyByScalar(m, -2, new Cesium.Matrix4());
   *
   * // m remains the same
   * // a = [-20.0, -22.0, -24.0, -26.0]
   * //     [-28.0, -30.0, -32.0, -34.0]
   * //     [-36.0, -38.0, -40.0, -42.0]
   * //     [-44.0, -46.0, -48.0, -50.0]
   */
  Matrix4.multiplyByScalar = function (matrix, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0] * scalar;
    result[1] = matrix[1] * scalar;
    result[2] = matrix[2] * scalar;
    result[3] = matrix[3] * scalar;
    result[4] = matrix[4] * scalar;
    result[5] = matrix[5] * scalar;
    result[6] = matrix[6] * scalar;
    result[7] = matrix[7] * scalar;
    result[8] = matrix[8] * scalar;
    result[9] = matrix[9] * scalar;
    result[10] = matrix[10] * scalar;
    result[11] = matrix[11] * scalar;
    result[12] = matrix[12] * scalar;
    result[13] = matrix[13] * scalar;
    result[14] = matrix[14] * scalar;
    result[15] = matrix[15] * scalar;
    return result;
  };

  /**
   * Computes a negated copy of the provided matrix.
   *
   * @param {Matrix4} matrix The matrix to negate.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * //create a new Matrix4 instance which is a negation of a Matrix4
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * var a = Cesium.Matrix4.negate(m, new Cesium.Matrix4());
   *
   * // m remains the same
   * // a = [-10.0, -11.0, -12.0, -13.0]
   * //     [-14.0, -15.0, -16.0, -17.0]
   * //     [-18.0, -19.0, -20.0, -21.0]
   * //     [-22.0, -23.0, -24.0, -25.0]
   */
  Matrix4.negate = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = -matrix[0];
    result[1] = -matrix[1];
    result[2] = -matrix[2];
    result[3] = -matrix[3];
    result[4] = -matrix[4];
    result[5] = -matrix[5];
    result[6] = -matrix[6];
    result[7] = -matrix[7];
    result[8] = -matrix[8];
    result[9] = -matrix[9];
    result[10] = -matrix[10];
    result[11] = -matrix[11];
    result[12] = -matrix[12];
    result[13] = -matrix[13];
    result[14] = -matrix[14];
    result[15] = -matrix[15];
    return result;
  };

  /**
   * Computes the transpose of the provided matrix.
   *
   * @param {Matrix4} matrix The matrix to transpose.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @example
   * //returns transpose of a Matrix4
   * // m = [10.0, 11.0, 12.0, 13.0]
   * //     [14.0, 15.0, 16.0, 17.0]
   * //     [18.0, 19.0, 20.0, 21.0]
   * //     [22.0, 23.0, 24.0, 25.0]
   *
   * var a = Cesium.Matrix4.transpose(m, new Cesium.Matrix4());
   *
   * // m remains the same
   * // a = [10.0, 14.0, 18.0, 22.0]
   * //     [11.0, 15.0, 19.0, 23.0]
   * //     [12.0, 16.0, 20.0, 24.0]
   * //     [13.0, 17.0, 21.0, 25.0]
   */
  Matrix4.transpose = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var matrix1 = matrix[1];
    var matrix2 = matrix[2];
    var matrix3 = matrix[3];
    var matrix6 = matrix[6];
    var matrix7 = matrix[7];
    var matrix11 = matrix[11];

    result[0] = matrix[0];
    result[1] = matrix[4];
    result[2] = matrix[8];
    result[3] = matrix[12];
    result[4] = matrix1;
    result[5] = matrix[5];
    result[6] = matrix[9];
    result[7] = matrix[13];
    result[8] = matrix2;
    result[9] = matrix6;
    result[10] = matrix[10];
    result[11] = matrix[14];
    result[12] = matrix3;
    result[13] = matrix7;
    result[14] = matrix11;
    result[15] = matrix[15];
    return result;
  };

  /**
   * Computes a matrix, which contains the absolute (unsigned) values of the provided matrix's elements.
   *
   * @param {Matrix4} matrix The matrix with signed elements.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.abs = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = Math.abs(matrix[0]);
    result[1] = Math.abs(matrix[1]);
    result[2] = Math.abs(matrix[2]);
    result[3] = Math.abs(matrix[3]);
    result[4] = Math.abs(matrix[4]);
    result[5] = Math.abs(matrix[5]);
    result[6] = Math.abs(matrix[6]);
    result[7] = Math.abs(matrix[7]);
    result[8] = Math.abs(matrix[8]);
    result[9] = Math.abs(matrix[9]);
    result[10] = Math.abs(matrix[10]);
    result[11] = Math.abs(matrix[11]);
    result[12] = Math.abs(matrix[12]);
    result[13] = Math.abs(matrix[13]);
    result[14] = Math.abs(matrix[14]);
    result[15] = Math.abs(matrix[15]);

    return result;
  };

  /**
   * Compares the provided matrices componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Matrix4} [left] The first matrix.
   * @param {Matrix4} [right] The second matrix.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   *
   * @example
   * //compares two Matrix4 instances
   *
   * // a = [10.0, 14.0, 18.0, 22.0]
   * //     [11.0, 15.0, 19.0, 23.0]
   * //     [12.0, 16.0, 20.0, 24.0]
   * //     [13.0, 17.0, 21.0, 25.0]
   *
   * // b = [10.0, 14.0, 18.0, 22.0]
   * //     [11.0, 15.0, 19.0, 23.0]
   * //     [12.0, 16.0, 20.0, 24.0]
   * //     [13.0, 17.0, 21.0, 25.0]
   *
   * if(Cesium.Matrix4.equals(a,b)) {
   *      console.log("Both matrices are equal");
   * } else {
   *      console.log("They are not equal");
   * }
   *
   * //Prints "Both matrices are equal" on the console
   */
  Matrix4.equals = function (left, right) {
    // Given that most matrices will be transformation matrices, the elements
    // are tested in order such that the test is likely to fail as early
    // as possible.  I _think_ this is just as friendly to the L1 cache
    // as testing in index order.  It is certainty faster in practice.
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        // Translation
        left[12] === right[12] &&
        left[13] === right[13] &&
        left[14] === right[14] &&
        // Rotation/scale
        left[0] === right[0] &&
        left[1] === right[1] &&
        left[2] === right[2] &&
        left[4] === right[4] &&
        left[5] === right[5] &&
        left[6] === right[6] &&
        left[8] === right[8] &&
        left[9] === right[9] &&
        left[10] === right[10] &&
        // Bottom row
        left[3] === right[3] &&
        left[7] === right[7] &&
        left[11] === right[11] &&
        left[15] === right[15])
    );
  };

  /**
   * Compares the provided matrices componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Matrix4} [left] The first matrix.
   * @param {Matrix4} [right] The second matrix.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   *
   * @example
   * //compares two Matrix4 instances
   *
   * // a = [10.5, 14.5, 18.5, 22.5]
   * //     [11.5, 15.5, 19.5, 23.5]
   * //     [12.5, 16.5, 20.5, 24.5]
   * //     [13.5, 17.5, 21.5, 25.5]
   *
   * // b = [10.0, 14.0, 18.0, 22.0]
   * //     [11.0, 15.0, 19.0, 23.0]
   * //     [12.0, 16.0, 20.0, 24.0]
   * //     [13.0, 17.0, 21.0, 25.0]
   *
   * if(Cesium.Matrix4.equalsEpsilon(a,b,0.1)){
   *      console.log("Difference between both the matrices is less than 0.1");
   * } else {
   *      console.log("Difference between both the matrices is not less than 0.1");
   * }
   *
   * //Prints "Difference between both the matrices is not less than 0.1" on the console
   */
  Matrix4.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left[0] - right[0]) <= epsilon &&
        Math.abs(left[1] - right[1]) <= epsilon &&
        Math.abs(left[2] - right[2]) <= epsilon &&
        Math.abs(left[3] - right[3]) <= epsilon &&
        Math.abs(left[4] - right[4]) <= epsilon &&
        Math.abs(left[5] - right[5]) <= epsilon &&
        Math.abs(left[6] - right[6]) <= epsilon &&
        Math.abs(left[7] - right[7]) <= epsilon &&
        Math.abs(left[8] - right[8]) <= epsilon &&
        Math.abs(left[9] - right[9]) <= epsilon &&
        Math.abs(left[10] - right[10]) <= epsilon &&
        Math.abs(left[11] - right[11]) <= epsilon &&
        Math.abs(left[12] - right[12]) <= epsilon &&
        Math.abs(left[13] - right[13]) <= epsilon &&
        Math.abs(left[14] - right[14]) <= epsilon &&
        Math.abs(left[15] - right[15]) <= epsilon)
    );
  };

  /**
   * Gets the translation portion of the provided matrix, assuming the matrix is a affine transformation matrix.
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Matrix4.getTranslation = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = matrix[12];
    result.y = matrix[13];
    result.z = matrix[14];
    return result;
  };

  /**
   * Gets the upper left 3x3 rotation matrix of the provided matrix, assuming the matrix is an affine transformation matrix.
   *
   * @param {Matrix4} matrix The matrix to use.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter.
   *
   * @example
   * // returns a Matrix3 instance from a Matrix4 instance
   *
   * // m = [10.0, 14.0, 18.0, 22.0]
   * //     [11.0, 15.0, 19.0, 23.0]
   * //     [12.0, 16.0, 20.0, 24.0]
   * //     [13.0, 17.0, 21.0, 25.0]
   *
   * var b = new Cesium.Matrix3();
   * Cesium.Matrix4.getMatrix3(m,b);
   *
   * // b = [10.0, 14.0, 18.0]
   * //     [11.0, 15.0, 19.0]
   * //     [12.0, 16.0, 20.0]
   */
  Matrix4.getMatrix3 = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[4];
    result[4] = matrix[5];
    result[5] = matrix[6];
    result[6] = matrix[8];
    result[7] = matrix[9];
    result[8] = matrix[10];
    return result;
  };

  var scratchInverseRotation = new Matrix3();
  var scratchMatrix3Zero = new Matrix3();
  var scratchBottomRow = new Cartesian4();
  var scratchExpectedBottomRow = new Cartesian4(0.0, 0.0, 0.0, 1.0);

  /**
   * Computes the inverse of the provided matrix using Cramers Rule.
   * If the determinant is zero, the matrix can not be inverted, and an exception is thrown.
   * If the matrix is an affine transformation matrix, it is more efficient
   * to invert it with {@link Matrix4.inverseTransformation}.
   *
   * @param {Matrix4} matrix The matrix to invert.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   *
   * @exception {RuntimeError} matrix is not invertible because its determinate is zero.
   */
  Matrix4.inverse = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');
    //
    // Ported from:
    //   ftp://download.intel.com/design/PentiumIII/sml/24504301.pdf
    //
    var src0 = matrix[0];
    var src1 = matrix[4];
    var src2 = matrix[8];
    var src3 = matrix[12];
    var src4 = matrix[1];
    var src5 = matrix[5];
    var src6 = matrix[9];
    var src7 = matrix[13];
    var src8 = matrix[2];
    var src9 = matrix[6];
    var src10 = matrix[10];
    var src11 = matrix[14];
    var src12 = matrix[3];
    var src13 = matrix[7];
    var src14 = matrix[11];
    var src15 = matrix[15];

    // calculate pairs for first 8 elements (cofactors)
    var tmp0 = src10 * src15;
    var tmp1 = src11 * src14;
    var tmp2 = src9 * src15;
    var tmp3 = src11 * src13;
    var tmp4 = src9 * src14;
    var tmp5 = src10 * src13;
    var tmp6 = src8 * src15;
    var tmp7 = src11 * src12;
    var tmp8 = src8 * src14;
    var tmp9 = src10 * src12;
    var tmp10 = src8 * src13;
    var tmp11 = src9 * src12;

    // calculate first 8 elements (cofactors)
    var dst0 =
      tmp0 * src5 +
      tmp3 * src6 +
      tmp4 * src7 -
      (tmp1 * src5 + tmp2 * src6 + tmp5 * src7);
    var dst1 =
      tmp1 * src4 +
      tmp6 * src6 +
      tmp9 * src7 -
      (tmp0 * src4 + tmp7 * src6 + tmp8 * src7);
    var dst2 =
      tmp2 * src4 +
      tmp7 * src5 +
      tmp10 * src7 -
      (tmp3 * src4 + tmp6 * src5 + tmp11 * src7);
    var dst3 =
      tmp5 * src4 +
      tmp8 * src5 +
      tmp11 * src6 -
      (tmp4 * src4 + tmp9 * src5 + tmp10 * src6);
    var dst4 =
      tmp1 * src1 +
      tmp2 * src2 +
      tmp5 * src3 -
      (tmp0 * src1 + tmp3 * src2 + tmp4 * src3);
    var dst5 =
      tmp0 * src0 +
      tmp7 * src2 +
      tmp8 * src3 -
      (tmp1 * src0 + tmp6 * src2 + tmp9 * src3);
    var dst6 =
      tmp3 * src0 +
      tmp6 * src1 +
      tmp11 * src3 -
      (tmp2 * src0 + tmp7 * src1 + tmp10 * src3);
    var dst7 =
      tmp4 * src0 +
      tmp9 * src1 +
      tmp10 * src2 -
      (tmp5 * src0 + tmp8 * src1 + tmp11 * src2);

    // calculate pairs for second 8 elements (cofactors)
    tmp0 = src2 * src7;
    tmp1 = src3 * src6;
    tmp2 = src1 * src7;
    tmp3 = src3 * src5;
    tmp4 = src1 * src6;
    tmp5 = src2 * src5;
    tmp6 = src0 * src7;
    tmp7 = src3 * src4;
    tmp8 = src0 * src6;
    tmp9 = src2 * src4;
    tmp10 = src0 * src5;
    tmp11 = src1 * src4;

    // calculate second 8 elements (cofactors)
    var dst8 =
      tmp0 * src13 +
      tmp3 * src14 +
      tmp4 * src15 -
      (tmp1 * src13 + tmp2 * src14 + tmp5 * src15);
    var dst9 =
      tmp1 * src12 +
      tmp6 * src14 +
      tmp9 * src15 -
      (tmp0 * src12 + tmp7 * src14 + tmp8 * src15);
    var dst10 =
      tmp2 * src12 +
      tmp7 * src13 +
      tmp10 * src15 -
      (tmp3 * src12 + tmp6 * src13 + tmp11 * src15);
    var dst11 =
      tmp5 * src12 +
      tmp8 * src13 +
      tmp11 * src14 -
      (tmp4 * src12 + tmp9 * src13 + tmp10 * src14);
    var dst12 =
      tmp2 * src10 +
      tmp5 * src11 +
      tmp1 * src9 -
      (tmp4 * src11 + tmp0 * src9 + tmp3 * src10);
    var dst13 =
      tmp8 * src11 +
      tmp0 * src8 +
      tmp7 * src10 -
      (tmp6 * src10 + tmp9 * src11 + tmp1 * src8);
    var dst14 =
      tmp6 * src9 +
      tmp11 * src11 +
      tmp3 * src8 -
      (tmp10 * src11 + tmp2 * src8 + tmp7 * src9);
    var dst15 =
      tmp10 * src10 +
      tmp4 * src8 +
      tmp9 * src9 -
      (tmp8 * src9 + tmp11 * src10 + tmp5 * src8);

    // calculate determinant
    var det = src0 * dst0 + src1 * dst1 + src2 * dst2 + src3 * dst3;

    if (Math.abs(det) < CesiumMath.EPSILON21) {
      // Special case for a zero scale matrix that can occur, for example,
      // when a model's node has a [0, 0, 0] scale.
      if (
        Matrix3.equalsEpsilon(
          Matrix4.getMatrix3(matrix, scratchInverseRotation),
          scratchMatrix3Zero,
          CesiumMath.EPSILON7
        ) &&
        Cartesian4.equals(
          Matrix4.getRow(matrix, 3, scratchBottomRow),
          scratchExpectedBottomRow
        )
      ) {
        result[0] = 0.0;
        result[1] = 0.0;
        result[2] = 0.0;
        result[3] = 0.0;
        result[4] = 0.0;
        result[5] = 0.0;
        result[6] = 0.0;
        result[7] = 0.0;
        result[8] = 0.0;
        result[9] = 0.0;
        result[10] = 0.0;
        result[11] = 0.0;
        result[12] = -matrix[12];
        result[13] = -matrix[13];
        result[14] = -matrix[14];
        result[15] = 1.0;
        return result;
      }

      throw new RuntimeError(
        "matrix is not invertible because its determinate is zero."
      );
    }

    // calculate matrix inverse
    det = 1.0 / det;

    result[0] = dst0 * det;
    result[1] = dst1 * det;
    result[2] = dst2 * det;
    result[3] = dst3 * det;
    result[4] = dst4 * det;
    result[5] = dst5 * det;
    result[6] = dst6 * det;
    result[7] = dst7 * det;
    result[8] = dst8 * det;
    result[9] = dst9 * det;
    result[10] = dst10 * det;
    result[11] = dst11 * det;
    result[12] = dst12 * det;
    result[13] = dst13 * det;
    result[14] = dst14 * det;
    result[15] = dst15 * det;
    return result;
  };

  /**
   * Computes the inverse of the provided matrix assuming it is
   * an affine transformation matrix, where the upper left 3x3 elements
   * are a rotation matrix, and the upper three elements in the fourth
   * column are the translation.  The bottom row is assumed to be [0, 0, 0, 1].
   * The matrix is not verified to be in the proper form.
   * This method is faster than computing the inverse for a general 4x4
   * matrix using {@link Matrix4.inverse}.
   *
   * @param {Matrix4} matrix The matrix to invert.
   * @param {Matrix4} result The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter.
   */
  Matrix4.inverseTransformation = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    //This function is an optimized version of the below 4 lines.
    //var rT = Matrix3.transpose(Matrix4.getMatrix3(matrix));
    //var rTN = Matrix3.negate(rT);
    //var rTT = Matrix3.multiplyByVector(rTN, Matrix4.getTranslation(matrix));
    //return Matrix4.fromRotationTranslation(rT, rTT, result);

    var matrix0 = matrix[0];
    var matrix1 = matrix[1];
    var matrix2 = matrix[2];
    var matrix4 = matrix[4];
    var matrix5 = matrix[5];
    var matrix6 = matrix[6];
    var matrix8 = matrix[8];
    var matrix9 = matrix[9];
    var matrix10 = matrix[10];

    var vX = matrix[12];
    var vY = matrix[13];
    var vZ = matrix[14];

    var x = -matrix0 * vX - matrix1 * vY - matrix2 * vZ;
    var y = -matrix4 * vX - matrix5 * vY - matrix6 * vZ;
    var z = -matrix8 * vX - matrix9 * vY - matrix10 * vZ;

    result[0] = matrix0;
    result[1] = matrix4;
    result[2] = matrix8;
    result[3] = 0.0;
    result[4] = matrix1;
    result[5] = matrix5;
    result[6] = matrix9;
    result[7] = 0.0;
    result[8] = matrix2;
    result[9] = matrix6;
    result[10] = matrix10;
    result[11] = 0.0;
    result[12] = x;
    result[13] = y;
    result[14] = z;
    result[15] = 1.0;
    return result;
  };

  /**
   * An immutable Matrix4 instance initialized to the identity matrix.
   *
   * @type {Matrix4}
   * @constant
   */
  Matrix4.IDENTITY = Object.freeze(
    new Matrix4(
      1.0,
      0.0,
      0.0,
      0.0,
      0.0,
      1.0,
      0.0,
      0.0,
      0.0,
      0.0,
      1.0,
      0.0,
      0.0,
      0.0,
      0.0,
      1.0
    )
  );

  /**
   * An immutable Matrix4 instance initialized to the zero matrix.
   *
   * @type {Matrix4}
   * @constant
   */
  Matrix4.ZERO = Object.freeze(
    new Matrix4(
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0,
      0.0
    )
  );

  /**
   * The index into Matrix4 for column 0, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN0ROW0 = 0;

  /**
   * The index into Matrix4 for column 0, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN0ROW1 = 1;

  /**
   * The index into Matrix4 for column 0, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN0ROW2 = 2;

  /**
   * The index into Matrix4 for column 0, row 3.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN0ROW3 = 3;

  /**
   * The index into Matrix4 for column 1, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN1ROW0 = 4;

  /**
   * The index into Matrix4 for column 1, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN1ROW1 = 5;

  /**
   * The index into Matrix4 for column 1, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN1ROW2 = 6;

  /**
   * The index into Matrix4 for column 1, row 3.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN1ROW3 = 7;

  /**
   * The index into Matrix4 for column 2, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN2ROW0 = 8;

  /**
   * The index into Matrix4 for column 2, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN2ROW1 = 9;

  /**
   * The index into Matrix4 for column 2, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN2ROW2 = 10;

  /**
   * The index into Matrix4 for column 2, row 3.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN2ROW3 = 11;

  /**
   * The index into Matrix4 for column 3, row 0.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN3ROW0 = 12;

  /**
   * The index into Matrix4 for column 3, row 1.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN3ROW1 = 13;

  /**
   * The index into Matrix4 for column 3, row 2.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN3ROW2 = 14;

  /**
   * The index into Matrix4 for column 3, row 3.
   *
   * @type {Number}
   * @constant
   */
  Matrix4.COLUMN3ROW3 = 15;

  Object.defineProperties(Matrix4.prototype, {
    /**
     * Gets the number of items in the collection.
     * @memberof Matrix4.prototype
     *
     * @type {Number}
     */
    length: {
      get: function () {
        return Matrix4.packedLength;
      },
    },
  });

  /**
   * Duplicates the provided Matrix4 instance.
   *
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if one was not provided.
   */
  Matrix4.prototype.clone = function (result) {
    return Matrix4.clone(this, result);
  };

  /**
   * Compares this matrix to the provided matrix componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Matrix4} [right] The right hand side matrix.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Matrix4.prototype.equals = function (right) {
    return Matrix4.equals(this, right);
  };

  /**
   * @private
   */
  Matrix4.equalsArray = function (matrix, array, offset) {
    return (
      matrix[0] === array[offset] &&
      matrix[1] === array[offset + 1] &&
      matrix[2] === array[offset + 2] &&
      matrix[3] === array[offset + 3] &&
      matrix[4] === array[offset + 4] &&
      matrix[5] === array[offset + 5] &&
      matrix[6] === array[offset + 6] &&
      matrix[7] === array[offset + 7] &&
      matrix[8] === array[offset + 8] &&
      matrix[9] === array[offset + 9] &&
      matrix[10] === array[offset + 10] &&
      matrix[11] === array[offset + 11] &&
      matrix[12] === array[offset + 12] &&
      matrix[13] === array[offset + 13] &&
      matrix[14] === array[offset + 14] &&
      matrix[15] === array[offset + 15]
    );
  };

  /**
   * Compares this matrix to the provided matrix componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Matrix4} [right] The right hand side matrix.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  Matrix4.prototype.equalsEpsilon = function (right, epsilon) {
    return Matrix4.equalsEpsilon(this, right, epsilon);
  };

  /**
   * Computes a string representing this Matrix with each row being
   * on a separate line and in the format '(column0, column1, column2, column3)'.
   *
   * @returns {String} A string representing the provided Matrix with each row being on a separate line and in the format '(column0, column1, column2, column3)'.
   */
  Matrix4.prototype.toString = function () {
    return (
      "(" +
      this[0] +
      ", " +
      this[4] +
      ", " +
      this[8] +
      ", " +
      this[12] +
      ")\n" +
      "(" +
      this[1] +
      ", " +
      this[5] +
      ", " +
      this[9] +
      ", " +
      this[13] +
      ")\n" +
      "(" +
      this[2] +
      ", " +
      this[6] +
      ", " +
      this[10] +
      ", " +
      this[14] +
      ")\n" +
      "(" +
      this[3] +
      ", " +
      this[7] +
      ", " +
      this[11] +
      ", " +
      this[15] +
      ")"
    );
  };

  /**
   * A two dimensional region specified as longitude and latitude coordinates.
   *
   * @alias Rectangle
   * @constructor
   *
   * @param {Number} [west=0.0] The westernmost longitude, in radians, in the range [-Pi, Pi].
   * @param {Number} [south=0.0] The southernmost latitude, in radians, in the range [-Pi/2, Pi/2].
   * @param {Number} [east=0.0] The easternmost longitude, in radians, in the range [-Pi, Pi].
   * @param {Number} [north=0.0] The northernmost latitude, in radians, in the range [-Pi/2, Pi/2].
   *
   * @see Packable
   */
  function Rectangle(west, south, east, north) {
    /**
     * The westernmost longitude in radians in the range [-Pi, Pi].
     *
     * @type {Number}
     * @default 0.0
     */
    this.west = defaultValue(west, 0.0);

    /**
     * The southernmost latitude in radians in the range [-Pi/2, Pi/2].
     *
     * @type {Number}
     * @default 0.0
     */
    this.south = defaultValue(south, 0.0);

    /**
     * The easternmost longitude in radians in the range [-Pi, Pi].
     *
     * @type {Number}
     * @default 0.0
     */
    this.east = defaultValue(east, 0.0);

    /**
     * The northernmost latitude in radians in the range [-Pi/2, Pi/2].
     *
     * @type {Number}
     * @default 0.0
     */
    this.north = defaultValue(north, 0.0);
  }

  Object.defineProperties(Rectangle.prototype, {
    /**
     * Gets the width of the rectangle in radians.
     * @memberof Rectangle.prototype
     * @type {Number}
     * @readonly
     */
    width: {
      get: function () {
        return Rectangle.computeWidth(this);
      },
    },

    /**
     * Gets the height of the rectangle in radians.
     * @memberof Rectangle.prototype
     * @type {Number}
     * @readonly
     */
    height: {
      get: function () {
        return Rectangle.computeHeight(this);
      },
    },
  });

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Rectangle.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Rectangle} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Rectangle.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.west;
    array[startingIndex++] = value.south;
    array[startingIndex++] = value.east;
    array[startingIndex] = value.north;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Rectangle} [result] The object into which to store the result.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if one was not provided.
   */
  Rectangle.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Rectangle();
    }

    result.west = array[startingIndex++];
    result.south = array[startingIndex++];
    result.east = array[startingIndex++];
    result.north = array[startingIndex];
    return result;
  };

  /**
   * Computes the width of a rectangle in radians.
   * @param {Rectangle} rectangle The rectangle to compute the width of.
   * @returns {Number} The width.
   */
  Rectangle.computeWidth = function (rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');
    var east = rectangle.east;
    var west = rectangle.west;
    if (east < west) {
      east += CesiumMath.TWO_PI;
    }
    return east - west;
  };

  /**
   * Computes the height of a rectangle in radians.
   * @param {Rectangle} rectangle The rectangle to compute the height of.
   * @returns {Number} The height.
   */
  Rectangle.computeHeight = function (rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');
    return rectangle.north - rectangle.south;
  };

  /**
   * Creates a rectangle given the boundary longitude and latitude in degrees.
   *
   * @param {Number} [west=0.0] The westernmost longitude in degrees in the range [-180.0, 180.0].
   * @param {Number} [south=0.0] The southernmost latitude in degrees in the range [-90.0, 90.0].
   * @param {Number} [east=0.0] The easternmost longitude in degrees in the range [-180.0, 180.0].
   * @param {Number} [north=0.0] The northernmost latitude in degrees in the range [-90.0, 90.0].
   * @param {Rectangle} [result] The object onto which to store the result, or undefined if a new instance should be created.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided.
   *
   * @example
   * var rectangle = Cesium.Rectangle.fromDegrees(0.0, 20.0, 10.0, 30.0);
   */
  Rectangle.fromDegrees = function (west, south, east, north, result) {
    west = CesiumMath.toRadians(defaultValue(west, 0.0));
    south = CesiumMath.toRadians(defaultValue(south, 0.0));
    east = CesiumMath.toRadians(defaultValue(east, 0.0));
    north = CesiumMath.toRadians(defaultValue(north, 0.0));

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;

    return result;
  };

  /**
   * Creates a rectangle given the boundary longitude and latitude in radians.
   *
   * @param {Number} [west=0.0] The westernmost longitude in radians in the range [-Math.PI, Math.PI].
   * @param {Number} [south=0.0] The southernmost latitude in radians in the range [-Math.PI/2, Math.PI/2].
   * @param {Number} [east=0.0] The easternmost longitude in radians in the range [-Math.PI, Math.PI].
   * @param {Number} [north=0.0] The northernmost latitude in radians in the range [-Math.PI/2, Math.PI/2].
   * @param {Rectangle} [result] The object onto which to store the result, or undefined if a new instance should be created.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided.
   *
   * @example
   * var rectangle = Cesium.Rectangle.fromRadians(0.0, Math.PI/4, Math.PI/8, 3*Math.PI/4);
   */
  Rectangle.fromRadians = function (west, south, east, north, result) {
    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = defaultValue(west, 0.0);
    result.south = defaultValue(south, 0.0);
    result.east = defaultValue(east, 0.0);
    result.north = defaultValue(north, 0.0);

    return result;
  };

  /**
   * Creates the smallest possible Rectangle that encloses all positions in the provided array.
   *
   * @param {Cartographic[]} cartographics The list of Cartographic instances.
   * @param {Rectangle} [result] The object onto which to store the result, or undefined if a new instance should be created.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided.
   */
  Rectangle.fromCartographicArray = function (cartographics, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartographics", cartographics);
    //>>includeEnd('debug');

    var west = Number.MAX_VALUE;
    var east = -Number.MAX_VALUE;
    var westOverIDL = Number.MAX_VALUE;
    var eastOverIDL = -Number.MAX_VALUE;
    var south = Number.MAX_VALUE;
    var north = -Number.MAX_VALUE;

    for (var i = 0, len = cartographics.length; i < len; i++) {
      var position = cartographics[i];
      west = Math.min(west, position.longitude);
      east = Math.max(east, position.longitude);
      south = Math.min(south, position.latitude);
      north = Math.max(north, position.latitude);

      var lonAdjusted =
        position.longitude >= 0
          ? position.longitude
          : position.longitude + CesiumMath.TWO_PI;
      westOverIDL = Math.min(westOverIDL, lonAdjusted);
      eastOverIDL = Math.max(eastOverIDL, lonAdjusted);
    }

    if (east - west > eastOverIDL - westOverIDL) {
      west = westOverIDL;
      east = eastOverIDL;

      if (east > CesiumMath.PI) {
        east = east - CesiumMath.TWO_PI;
      }
      if (west > CesiumMath.PI) {
        west = west - CesiumMath.TWO_PI;
      }
    }

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Creates the smallest possible Rectangle that encloses all positions in the provided array.
   *
   * @param {Cartesian3[]} cartesians The list of Cartesian instances.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid the cartesians are on.
   * @param {Rectangle} [result] The object onto which to store the result, or undefined if a new instance should be created.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided.
   */
  Rectangle.fromCartesianArray = function (cartesians, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    //>>includeEnd('debug');
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var west = Number.MAX_VALUE;
    var east = -Number.MAX_VALUE;
    var westOverIDL = Number.MAX_VALUE;
    var eastOverIDL = -Number.MAX_VALUE;
    var south = Number.MAX_VALUE;
    var north = -Number.MAX_VALUE;

    for (var i = 0, len = cartesians.length; i < len; i++) {
      var position = ellipsoid.cartesianToCartographic(cartesians[i]);
      west = Math.min(west, position.longitude);
      east = Math.max(east, position.longitude);
      south = Math.min(south, position.latitude);
      north = Math.max(north, position.latitude);

      var lonAdjusted =
        position.longitude >= 0
          ? position.longitude
          : position.longitude + CesiumMath.TWO_PI;
      westOverIDL = Math.min(westOverIDL, lonAdjusted);
      eastOverIDL = Math.max(eastOverIDL, lonAdjusted);
    }

    if (east - west > eastOverIDL - westOverIDL) {
      west = westOverIDL;
      east = eastOverIDL;

      if (east > CesiumMath.PI) {
        east = east - CesiumMath.TWO_PI;
      }
      if (west > CesiumMath.PI) {
        west = west - CesiumMath.TWO_PI;
      }
    }

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Duplicates a Rectangle.
   *
   * @param {Rectangle} rectangle The rectangle to clone.
   * @param {Rectangle} [result] The object onto which to store the result, or undefined if a new instance should be created.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided. (Returns undefined if rectangle is undefined)
   */
  Rectangle.clone = function (rectangle, result) {
    if (!defined(rectangle)) {
      return undefined;
    }

    if (!defined(result)) {
      return new Rectangle(
        rectangle.west,
        rectangle.south,
        rectangle.east,
        rectangle.north
      );
    }

    result.west = rectangle.west;
    result.south = rectangle.south;
    result.east = rectangle.east;
    result.north = rectangle.north;
    return result;
  };

  /**
   * Compares the provided Rectangles componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Rectangle} [left] The first Rectangle.
   * @param {Rectangle} [right] The second Rectangle.
   * @param {Number} [absoluteEpsilon=0] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Rectangle.equalsEpsilon = function (left, right, absoluteEpsilon) {
    absoluteEpsilon = defaultValue(absoluteEpsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left.west - right.west) <= absoluteEpsilon &&
        Math.abs(left.south - right.south) <= absoluteEpsilon &&
        Math.abs(left.east - right.east) <= absoluteEpsilon &&
        Math.abs(left.north - right.north) <= absoluteEpsilon)
    );
  };

  /**
   * Duplicates this Rectangle.
   *
   * @param {Rectangle} [result] The object onto which to store the result.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided.
   */
  Rectangle.prototype.clone = function (result) {
    return Rectangle.clone(this, result);
  };

  /**
   * Compares the provided Rectangle with this Rectangle componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Rectangle} [other] The Rectangle to compare.
   * @returns {Boolean} <code>true</code> if the Rectangles are equal, <code>false</code> otherwise.
   */
  Rectangle.prototype.equals = function (other) {
    return Rectangle.equals(this, other);
  };

  /**
   * Compares the provided rectangles and returns <code>true</code> if they are equal,
   * <code>false</code> otherwise.
   *
   * @param {Rectangle} [left] The first Rectangle.
   * @param {Rectangle} [right] The second Rectangle.
   * @returns {Boolean} <code>true</code> if left and right are equal; otherwise <code>false</code>.
   */
  Rectangle.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.west === right.west &&
        left.south === right.south &&
        left.east === right.east &&
        left.north === right.north)
    );
  };

  /**
   * Compares the provided Rectangle with this Rectangle componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Rectangle} [other] The Rectangle to compare.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if the Rectangles are within the provided epsilon, <code>false</code> otherwise.
   */
  Rectangle.prototype.equalsEpsilon = function (other, epsilon) {
    return Rectangle.equalsEpsilon(this, other, epsilon);
  };

  /**
   * Checks a Rectangle's properties and throws if they are not in valid ranges.
   *
   * @param {Rectangle} rectangle The rectangle to validate
   *
   * @exception {DeveloperError} <code>north</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
   * @exception {DeveloperError} <code>south</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
   * @exception {DeveloperError} <code>east</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
   * @exception {DeveloperError} <code>west</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
   */
  Rectangle.validate = function (rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);

    var north = rectangle.north;
    Check.typeOf.number.greaterThanOrEquals(
      "north",
      north,
      -CesiumMath.PI_OVER_TWO
    );
    Check.typeOf.number.lessThanOrEquals("north", north, CesiumMath.PI_OVER_TWO);

    var south = rectangle.south;
    Check.typeOf.number.greaterThanOrEquals(
      "south",
      south,
      -CesiumMath.PI_OVER_TWO
    );
    Check.typeOf.number.lessThanOrEquals("south", south, CesiumMath.PI_OVER_TWO);

    var west = rectangle.west;
    Check.typeOf.number.greaterThanOrEquals("west", west, -Math.PI);
    Check.typeOf.number.lessThanOrEquals("west", west, Math.PI);

    var east = rectangle.east;
    Check.typeOf.number.greaterThanOrEquals("east", east, -Math.PI);
    Check.typeOf.number.lessThanOrEquals("east", east, Math.PI);
    //>>includeEnd('debug');
  };

  /**
   * Computes the southwest corner of a rectangle.
   *
   * @param {Rectangle} rectangle The rectangle for which to find the corner
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if none was provided.
   */
  Rectangle.southwest = function (rectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Cartographic(rectangle.west, rectangle.south);
    }
    result.longitude = rectangle.west;
    result.latitude = rectangle.south;
    result.height = 0.0;
    return result;
  };

  /**
   * Computes the northwest corner of a rectangle.
   *
   * @param {Rectangle} rectangle The rectangle for which to find the corner
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if none was provided.
   */
  Rectangle.northwest = function (rectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Cartographic(rectangle.west, rectangle.north);
    }
    result.longitude = rectangle.west;
    result.latitude = rectangle.north;
    result.height = 0.0;
    return result;
  };

  /**
   * Computes the northeast corner of a rectangle.
   *
   * @param {Rectangle} rectangle The rectangle for which to find the corner
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if none was provided.
   */
  Rectangle.northeast = function (rectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Cartographic(rectangle.east, rectangle.north);
    }
    result.longitude = rectangle.east;
    result.latitude = rectangle.north;
    result.height = 0.0;
    return result;
  };

  /**
   * Computes the southeast corner of a rectangle.
   *
   * @param {Rectangle} rectangle The rectangle for which to find the corner
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if none was provided.
   */
  Rectangle.southeast = function (rectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Cartographic(rectangle.east, rectangle.south);
    }
    result.longitude = rectangle.east;
    result.latitude = rectangle.south;
    result.height = 0.0;
    return result;
  };

  /**
   * Computes the center of a rectangle.
   *
   * @param {Rectangle} rectangle The rectangle for which to find the center
   * @param {Cartographic} [result] The object onto which to store the result.
   * @returns {Cartographic} The modified result parameter or a new Cartographic instance if none was provided.
   */
  Rectangle.center = function (rectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    var east = rectangle.east;
    var west = rectangle.west;

    if (east < west) {
      east += CesiumMath.TWO_PI;
    }

    var longitude = CesiumMath.negativePiToPi((west + east) * 0.5);
    var latitude = (rectangle.south + rectangle.north) * 0.5;

    if (!defined(result)) {
      return new Cartographic(longitude, latitude);
    }

    result.longitude = longitude;
    result.latitude = latitude;
    result.height = 0.0;
    return result;
  };

  /**
   * Computes the intersection of two rectangles.  This function assumes that the rectangle's coordinates are
   * latitude and longitude in radians and produces a correct intersection, taking into account the fact that
   * the same angle can be represented with multiple values as well as the wrapping of longitude at the
   * anti-meridian.  For a simple intersection that ignores these factors and can be used with projected
   * coordinates, see {@link Rectangle.simpleIntersection}.
   *
   * @param {Rectangle} rectangle On rectangle to find an intersection
   * @param {Rectangle} otherRectangle Another rectangle to find an intersection
   * @param {Rectangle} [result] The object onto which to store the result.
   * @returns {Rectangle|undefined} The modified result parameter, a new Rectangle instance if none was provided or undefined if there is no intersection.
   */
  Rectangle.intersection = function (rectangle, otherRectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Check.typeOf.object("otherRectangle", otherRectangle);
    //>>includeEnd('debug');

    var rectangleEast = rectangle.east;
    var rectangleWest = rectangle.west;

    var otherRectangleEast = otherRectangle.east;
    var otherRectangleWest = otherRectangle.west;

    if (rectangleEast < rectangleWest && otherRectangleEast > 0.0) {
      rectangleEast += CesiumMath.TWO_PI;
    } else if (otherRectangleEast < otherRectangleWest && rectangleEast > 0.0) {
      otherRectangleEast += CesiumMath.TWO_PI;
    }

    if (rectangleEast < rectangleWest && otherRectangleWest < 0.0) {
      otherRectangleWest += CesiumMath.TWO_PI;
    } else if (otherRectangleEast < otherRectangleWest && rectangleWest < 0.0) {
      rectangleWest += CesiumMath.TWO_PI;
    }

    var west = CesiumMath.negativePiToPi(
      Math.max(rectangleWest, otherRectangleWest)
    );
    var east = CesiumMath.negativePiToPi(
      Math.min(rectangleEast, otherRectangleEast)
    );

    if (
      (rectangle.west < rectangle.east ||
        otherRectangle.west < otherRectangle.east) &&
      east <= west
    ) {
      return undefined;
    }

    var south = Math.max(rectangle.south, otherRectangle.south);
    var north = Math.min(rectangle.north, otherRectangle.north);

    if (south >= north) {
      return undefined;
    }

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }
    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Computes a simple intersection of two rectangles.  Unlike {@link Rectangle.intersection}, this function
   * does not attempt to put the angular coordinates into a consistent range or to account for crossing the
   * anti-meridian.  As such, it can be used for rectangles where the coordinates are not simply latitude
   * and longitude (i.e. projected coordinates).
   *
   * @param {Rectangle} rectangle On rectangle to find an intersection
   * @param {Rectangle} otherRectangle Another rectangle to find an intersection
   * @param {Rectangle} [result] The object onto which to store the result.
   * @returns {Rectangle|undefined} The modified result parameter, a new Rectangle instance if none was provided or undefined if there is no intersection.
   */
  Rectangle.simpleIntersection = function (rectangle, otherRectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Check.typeOf.object("otherRectangle", otherRectangle);
    //>>includeEnd('debug');

    var west = Math.max(rectangle.west, otherRectangle.west);
    var south = Math.max(rectangle.south, otherRectangle.south);
    var east = Math.min(rectangle.east, otherRectangle.east);
    var north = Math.min(rectangle.north, otherRectangle.north);

    if (south >= north || west >= east) {
      return undefined;
    }

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Computes a rectangle that is the union of two rectangles.
   *
   * @param {Rectangle} rectangle A rectangle to enclose in rectangle.
   * @param {Rectangle} otherRectangle A rectangle to enclose in a rectangle.
   * @param {Rectangle} [result] The object onto which to store the result.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if none was provided.
   */
  Rectangle.union = function (rectangle, otherRectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Check.typeOf.object("otherRectangle", otherRectangle);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Rectangle();
    }

    var rectangleEast = rectangle.east;
    var rectangleWest = rectangle.west;

    var otherRectangleEast = otherRectangle.east;
    var otherRectangleWest = otherRectangle.west;

    if (rectangleEast < rectangleWest && otherRectangleEast > 0.0) {
      rectangleEast += CesiumMath.TWO_PI;
    } else if (otherRectangleEast < otherRectangleWest && rectangleEast > 0.0) {
      otherRectangleEast += CesiumMath.TWO_PI;
    }

    if (rectangleEast < rectangleWest && otherRectangleWest < 0.0) {
      otherRectangleWest += CesiumMath.TWO_PI;
    } else if (otherRectangleEast < otherRectangleWest && rectangleWest < 0.0) {
      rectangleWest += CesiumMath.TWO_PI;
    }

    var west = CesiumMath.convertLongitudeRange(
      Math.min(rectangleWest, otherRectangleWest)
    );
    var east = CesiumMath.convertLongitudeRange(
      Math.max(rectangleEast, otherRectangleEast)
    );

    result.west = west;
    result.south = Math.min(rectangle.south, otherRectangle.south);
    result.east = east;
    result.north = Math.max(rectangle.north, otherRectangle.north);

    return result;
  };

  /**
   * Computes a rectangle by enlarging the provided rectangle until it contains the provided cartographic.
   *
   * @param {Rectangle} rectangle A rectangle to expand.
   * @param {Cartographic} cartographic A cartographic to enclose in a rectangle.
   * @param {Rectangle} [result] The object onto which to store the result.
   * @returns {Rectangle} The modified result parameter or a new Rectangle instance if one was not provided.
   */
  Rectangle.expand = function (rectangle, cartographic, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Check.typeOf.object("cartographic", cartographic);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Rectangle();
    }

    result.west = Math.min(rectangle.west, cartographic.longitude);
    result.south = Math.min(rectangle.south, cartographic.latitude);
    result.east = Math.max(rectangle.east, cartographic.longitude);
    result.north = Math.max(rectangle.north, cartographic.latitude);

    return result;
  };

  /**
   * Returns true if the cartographic is on or inside the rectangle, false otherwise.
   *
   * @param {Rectangle} rectangle The rectangle
   * @param {Cartographic} cartographic The cartographic to test.
   * @returns {Boolean} true if the provided cartographic is inside the rectangle, false otherwise.
   */
  Rectangle.contains = function (rectangle, cartographic) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Check.typeOf.object("cartographic", cartographic);
    //>>includeEnd('debug');

    var longitude = cartographic.longitude;
    var latitude = cartographic.latitude;

    var west = rectangle.west;
    var east = rectangle.east;

    if (east < west) {
      east += CesiumMath.TWO_PI;
      if (longitude < 0.0) {
        longitude += CesiumMath.TWO_PI;
      }
    }
    return (
      (longitude > west ||
        CesiumMath.equalsEpsilon(longitude, west, CesiumMath.EPSILON14)) &&
      (longitude < east ||
        CesiumMath.equalsEpsilon(longitude, east, CesiumMath.EPSILON14)) &&
      latitude >= rectangle.south &&
      latitude <= rectangle.north
    );
  };

  var subsampleLlaScratch = new Cartographic();
  /**
   * Samples a rectangle so that it includes a list of Cartesian points suitable for passing to
   * {@link BoundingSphere#fromPoints}.  Sampling is necessary to account
   * for rectangles that cover the poles or cross the equator.
   *
   * @param {Rectangle} rectangle The rectangle to subsample.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid to use.
   * @param {Number} [surfaceHeight=0.0] The height of the rectangle above the ellipsoid.
   * @param {Cartesian3[]} [result] The array of Cartesians onto which to store the result.
   * @returns {Cartesian3[]} The modified result parameter or a new Array of Cartesians instances if none was provided.
   */
  Rectangle.subsample = function (rectangle, ellipsoid, surfaceHeight, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    surfaceHeight = defaultValue(surfaceHeight, 0.0);

    if (!defined(result)) {
      result = [];
    }
    var length = 0;

    var north = rectangle.north;
    var south = rectangle.south;
    var east = rectangle.east;
    var west = rectangle.west;

    var lla = subsampleLlaScratch;
    lla.height = surfaceHeight;

    lla.longitude = west;
    lla.latitude = north;
    result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
    length++;

    lla.longitude = east;
    result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
    length++;

    lla.latitude = south;
    result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
    length++;

    lla.longitude = west;
    result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
    length++;

    if (north < 0.0) {
      lla.latitude = north;
    } else if (south > 0.0) {
      lla.latitude = south;
    } else {
      lla.latitude = 0.0;
    }

    for (var i = 1; i < 8; ++i) {
      lla.longitude = -Math.PI + i * CesiumMath.PI_OVER_TWO;
      if (Rectangle.contains(rectangle, lla)) {
        result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
        length++;
      }
    }

    if (lla.latitude === 0.0) {
      lla.longitude = west;
      result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
      length++;
      lla.longitude = east;
      result[length] = ellipsoid.cartographicToCartesian(lla, result[length]);
      length++;
    }
    result.length = length;
    return result;
  };

  /**
   * The largest possible rectangle.
   *
   * @type {Rectangle}
   * @constant
   */
  Rectangle.MAX_VALUE = Object.freeze(
    new Rectangle(
      -Math.PI,
      -CesiumMath.PI_OVER_TWO,
      Math.PI,
      CesiumMath.PI_OVER_TWO
    )
  );

  /**
   * A bounding sphere with a center and a radius.
   * @alias BoundingSphere
   * @constructor
   *
   * @param {Cartesian3} [center=Cartesian3.ZERO] The center of the bounding sphere.
   * @param {Number} [radius=0.0] The radius of the bounding sphere.
   *
   * @see AxisAlignedBoundingBox
   * @see BoundingRectangle
   * @see Packable
   */
  function BoundingSphere(center, radius) {
    /**
     * The center point of the sphere.
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.center = Cartesian3.clone(defaultValue(center, Cartesian3.ZERO));

    /**
     * The radius of the sphere.
     * @type {Number}
     * @default 0.0
     */
    this.radius = defaultValue(radius, 0.0);
  }

  var fromPointsXMin = new Cartesian3();
  var fromPointsYMin = new Cartesian3();
  var fromPointsZMin = new Cartesian3();
  var fromPointsXMax = new Cartesian3();
  var fromPointsYMax = new Cartesian3();
  var fromPointsZMax = new Cartesian3();
  var fromPointsCurrentPos = new Cartesian3();
  var fromPointsScratch = new Cartesian3();
  var fromPointsRitterCenter = new Cartesian3();
  var fromPointsMinBoxPt = new Cartesian3();
  var fromPointsMaxBoxPt = new Cartesian3();
  var fromPointsNaiveCenterScratch = new Cartesian3();
  var volumeConstant = (4.0 / 3.0) * CesiumMath.PI;

  /**
   * Computes a tight-fitting bounding sphere enclosing a list of 3D Cartesian points.
   * The bounding sphere is computed by running two algorithms, a naive algorithm and
   * Ritter's algorithm. The smaller of the two spheres is used to ensure a tight fit.
   *
   * @param {Cartesian3[]} [positions] An array of points that the bounding sphere will enclose.  Each point must have <code>x</code>, <code>y</code>, and <code>z</code> properties.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if one was not provided.
   *
   * @see {@link http://help.agi.com/AGIComponents/html/BlogBoundingSphere.htm|Bounding Sphere computation article}
   */
  BoundingSphere.fromPoints = function (positions, result) {
    if (!defined(result)) {
      result = new BoundingSphere();
    }

    if (!defined(positions) || positions.length === 0) {
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      result.radius = 0.0;
      return result;
    }

    var currentPos = Cartesian3.clone(positions[0], fromPointsCurrentPos);

    var xMin = Cartesian3.clone(currentPos, fromPointsXMin);
    var yMin = Cartesian3.clone(currentPos, fromPointsYMin);
    var zMin = Cartesian3.clone(currentPos, fromPointsZMin);

    var xMax = Cartesian3.clone(currentPos, fromPointsXMax);
    var yMax = Cartesian3.clone(currentPos, fromPointsYMax);
    var zMax = Cartesian3.clone(currentPos, fromPointsZMax);

    var numPositions = positions.length;
    var i;
    for (i = 1; i < numPositions; i++) {
      Cartesian3.clone(positions[i], currentPos);

      var x = currentPos.x;
      var y = currentPos.y;
      var z = currentPos.z;

      // Store points containing the the smallest and largest components
      if (x < xMin.x) {
        Cartesian3.clone(currentPos, xMin);
      }

      if (x > xMax.x) {
        Cartesian3.clone(currentPos, xMax);
      }

      if (y < yMin.y) {
        Cartesian3.clone(currentPos, yMin);
      }

      if (y > yMax.y) {
        Cartesian3.clone(currentPos, yMax);
      }

      if (z < zMin.z) {
        Cartesian3.clone(currentPos, zMin);
      }

      if (z > zMax.z) {
        Cartesian3.clone(currentPos, zMax);
      }
    }

    // Compute x-, y-, and z-spans (Squared distances b/n each component's min. and max.).
    var xSpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(xMax, xMin, fromPointsScratch)
    );
    var ySpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(yMax, yMin, fromPointsScratch)
    );
    var zSpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(zMax, zMin, fromPointsScratch)
    );

    // Set the diameter endpoints to the largest span.
    var diameter1 = xMin;
    var diameter2 = xMax;
    var maxSpan = xSpan;
    if (ySpan > maxSpan) {
      maxSpan = ySpan;
      diameter1 = yMin;
      diameter2 = yMax;
    }
    if (zSpan > maxSpan) {
      maxSpan = zSpan;
      diameter1 = zMin;
      diameter2 = zMax;
    }

    // Calculate the center of the initial sphere found by Ritter's algorithm
    var ritterCenter = fromPointsRitterCenter;
    ritterCenter.x = (diameter1.x + diameter2.x) * 0.5;
    ritterCenter.y = (diameter1.y + diameter2.y) * 0.5;
    ritterCenter.z = (diameter1.z + diameter2.z) * 0.5;

    // Calculate the radius of the initial sphere found by Ritter's algorithm
    var radiusSquared = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(diameter2, ritterCenter, fromPointsScratch)
    );
    var ritterRadius = Math.sqrt(radiusSquared);

    // Find the center of the sphere found using the Naive method.
    var minBoxPt = fromPointsMinBoxPt;
    minBoxPt.x = xMin.x;
    minBoxPt.y = yMin.y;
    minBoxPt.z = zMin.z;

    var maxBoxPt = fromPointsMaxBoxPt;
    maxBoxPt.x = xMax.x;
    maxBoxPt.y = yMax.y;
    maxBoxPt.z = zMax.z;

    var naiveCenter = Cartesian3.midpoint(
      minBoxPt,
      maxBoxPt,
      fromPointsNaiveCenterScratch
    );

    // Begin 2nd pass to find naive radius and modify the ritter sphere.
    var naiveRadius = 0;
    for (i = 0; i < numPositions; i++) {
      Cartesian3.clone(positions[i], currentPos);

      // Find the furthest point from the naive center to calculate the naive radius.
      var r = Cartesian3.magnitude(
        Cartesian3.subtract(currentPos, naiveCenter, fromPointsScratch)
      );
      if (r > naiveRadius) {
        naiveRadius = r;
      }

      // Make adjustments to the Ritter Sphere to include all points.
      var oldCenterToPointSquared = Cartesian3.magnitudeSquared(
        Cartesian3.subtract(currentPos, ritterCenter, fromPointsScratch)
      );
      if (oldCenterToPointSquared > radiusSquared) {
        var oldCenterToPoint = Math.sqrt(oldCenterToPointSquared);
        // Calculate new radius to include the point that lies outside
        ritterRadius = (ritterRadius + oldCenterToPoint) * 0.5;
        radiusSquared = ritterRadius * ritterRadius;
        // Calculate center of new Ritter sphere
        var oldToNew = oldCenterToPoint - ritterRadius;
        ritterCenter.x =
          (ritterRadius * ritterCenter.x + oldToNew * currentPos.x) /
          oldCenterToPoint;
        ritterCenter.y =
          (ritterRadius * ritterCenter.y + oldToNew * currentPos.y) /
          oldCenterToPoint;
        ritterCenter.z =
          (ritterRadius * ritterCenter.z + oldToNew * currentPos.z) /
          oldCenterToPoint;
      }
    }

    if (ritterRadius < naiveRadius) {
      Cartesian3.clone(ritterCenter, result.center);
      result.radius = ritterRadius;
    } else {
      Cartesian3.clone(naiveCenter, result.center);
      result.radius = naiveRadius;
    }

    return result;
  };

  var defaultProjection = new GeographicProjection();
  var fromRectangle2DLowerLeft = new Cartesian3();
  var fromRectangle2DUpperRight = new Cartesian3();
  var fromRectangle2DSouthwest = new Cartographic();
  var fromRectangle2DNortheast = new Cartographic();

  /**
   * Computes a bounding sphere from a rectangle projected in 2D.
   *
   * @param {Rectangle} [rectangle] The rectangle around which to create a bounding sphere.
   * @param {Object} [projection=GeographicProjection] The projection used to project the rectangle into 2D.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.fromRectangle2D = function (rectangle, projection, result) {
    return BoundingSphere.fromRectangleWithHeights2D(
      rectangle,
      projection,
      0.0,
      0.0,
      result
    );
  };

  /**
   * Computes a bounding sphere from a rectangle projected in 2D.  The bounding sphere accounts for the
   * object's minimum and maximum heights over the rectangle.
   *
   * @param {Rectangle} [rectangle] The rectangle around which to create a bounding sphere.
   * @param {Object} [projection=GeographicProjection] The projection used to project the rectangle into 2D.
   * @param {Number} [minimumHeight=0.0] The minimum height over the rectangle.
   * @param {Number} [maximumHeight=0.0] The maximum height over the rectangle.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.fromRectangleWithHeights2D = function (
    rectangle,
    projection,
    minimumHeight,
    maximumHeight,
    result
  ) {
    if (!defined(result)) {
      result = new BoundingSphere();
    }

    if (!defined(rectangle)) {
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      result.radius = 0.0;
      return result;
    }

    projection = defaultValue(projection, defaultProjection);

    Rectangle.southwest(rectangle, fromRectangle2DSouthwest);
    fromRectangle2DSouthwest.height = minimumHeight;
    Rectangle.northeast(rectangle, fromRectangle2DNortheast);
    fromRectangle2DNortheast.height = maximumHeight;

    var lowerLeft = projection.project(
      fromRectangle2DSouthwest,
      fromRectangle2DLowerLeft
    );
    var upperRight = projection.project(
      fromRectangle2DNortheast,
      fromRectangle2DUpperRight
    );

    var width = upperRight.x - lowerLeft.x;
    var height = upperRight.y - lowerLeft.y;
    var elevation = upperRight.z - lowerLeft.z;

    result.radius =
      Math.sqrt(width * width + height * height + elevation * elevation) * 0.5;
    var center = result.center;
    center.x = lowerLeft.x + width * 0.5;
    center.y = lowerLeft.y + height * 0.5;
    center.z = lowerLeft.z + elevation * 0.5;
    return result;
  };

  var fromRectangle3DScratch = [];

  /**
   * Computes a bounding sphere from a rectangle in 3D. The bounding sphere is created using a subsample of points
   * on the ellipsoid and contained in the rectangle. It may not be accurate for all rectangles on all types of ellipsoids.
   *
   * @param {Rectangle} [rectangle] The valid rectangle used to create a bounding sphere.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid used to determine positions of the rectangle.
   * @param {Number} [surfaceHeight=0.0] The height above the surface of the ellipsoid.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.fromRectangle3D = function (
    rectangle,
    ellipsoid,
    surfaceHeight,
    result
  ) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    surfaceHeight = defaultValue(surfaceHeight, 0.0);

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    if (!defined(rectangle)) {
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      result.radius = 0.0;
      return result;
    }

    var positions = Rectangle.subsample(
      rectangle,
      ellipsoid,
      surfaceHeight,
      fromRectangle3DScratch
    );
    return BoundingSphere.fromPoints(positions, result);
  };

  /**
   * Computes a tight-fitting bounding sphere enclosing a list of 3D points, where the points are
   * stored in a flat array in X, Y, Z, order.  The bounding sphere is computed by running two
   * algorithms, a naive algorithm and Ritter's algorithm. The smaller of the two spheres is used to
   * ensure a tight fit.
   *
   * @param {Number[]} [positions] An array of points that the bounding sphere will enclose.  Each point
   *        is formed from three elements in the array in the order X, Y, Z.
   * @param {Cartesian3} [center=Cartesian3.ZERO] The position to which the positions are relative, which need not be the
   *        origin of the coordinate system.  This is useful when the positions are to be used for
   *        relative-to-center (RTC) rendering.
   * @param {Number} [stride=3] The number of array elements per vertex.  It must be at least 3, but it may
   *        be higher.  Regardless of the value of this parameter, the X coordinate of the first position
   *        is at array index 0, the Y coordinate is at array index 1, and the Z coordinate is at array index
   *        2.  When stride is 3, the X coordinate of the next position then begins at array index 3.  If
   *        the stride is 5, however, two array elements are skipped and the next position begins at array
   *        index 5.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if one was not provided.
   *
   * @example
   * // Compute the bounding sphere from 3 positions, each specified relative to a center.
   * // In addition to the X, Y, and Z coordinates, the points array contains two additional
   * // elements per point which are ignored for the purpose of computing the bounding sphere.
   * var center = new Cesium.Cartesian3(1.0, 2.0, 3.0);
   * var points = [1.0, 2.0, 3.0, 0.1, 0.2,
   *               4.0, 5.0, 6.0, 0.1, 0.2,
   *               7.0, 8.0, 9.0, 0.1, 0.2];
   * var sphere = Cesium.BoundingSphere.fromVertices(points, center, 5);
   *
   * @see {@link http://blogs.agi.com/insight3d/index.php/2008/02/04/a-bounding/|Bounding Sphere computation article}
   */
  BoundingSphere.fromVertices = function (positions, center, stride, result) {
    if (!defined(result)) {
      result = new BoundingSphere();
    }

    if (!defined(positions) || positions.length === 0) {
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      result.radius = 0.0;
      return result;
    }

    center = defaultValue(center, Cartesian3.ZERO);

    stride = defaultValue(stride, 3);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("stride", stride, 3);
    //>>includeEnd('debug');

    var currentPos = fromPointsCurrentPos;
    currentPos.x = positions[0] + center.x;
    currentPos.y = positions[1] + center.y;
    currentPos.z = positions[2] + center.z;

    var xMin = Cartesian3.clone(currentPos, fromPointsXMin);
    var yMin = Cartesian3.clone(currentPos, fromPointsYMin);
    var zMin = Cartesian3.clone(currentPos, fromPointsZMin);

    var xMax = Cartesian3.clone(currentPos, fromPointsXMax);
    var yMax = Cartesian3.clone(currentPos, fromPointsYMax);
    var zMax = Cartesian3.clone(currentPos, fromPointsZMax);

    var numElements = positions.length;
    var i;
    for (i = 0; i < numElements; i += stride) {
      var x = positions[i] + center.x;
      var y = positions[i + 1] + center.y;
      var z = positions[i + 2] + center.z;

      currentPos.x = x;
      currentPos.y = y;
      currentPos.z = z;

      // Store points containing the the smallest and largest components
      if (x < xMin.x) {
        Cartesian3.clone(currentPos, xMin);
      }

      if (x > xMax.x) {
        Cartesian3.clone(currentPos, xMax);
      }

      if (y < yMin.y) {
        Cartesian3.clone(currentPos, yMin);
      }

      if (y > yMax.y) {
        Cartesian3.clone(currentPos, yMax);
      }

      if (z < zMin.z) {
        Cartesian3.clone(currentPos, zMin);
      }

      if (z > zMax.z) {
        Cartesian3.clone(currentPos, zMax);
      }
    }

    // Compute x-, y-, and z-spans (Squared distances b/n each component's min. and max.).
    var xSpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(xMax, xMin, fromPointsScratch)
    );
    var ySpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(yMax, yMin, fromPointsScratch)
    );
    var zSpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(zMax, zMin, fromPointsScratch)
    );

    // Set the diameter endpoints to the largest span.
    var diameter1 = xMin;
    var diameter2 = xMax;
    var maxSpan = xSpan;
    if (ySpan > maxSpan) {
      maxSpan = ySpan;
      diameter1 = yMin;
      diameter2 = yMax;
    }
    if (zSpan > maxSpan) {
      maxSpan = zSpan;
      diameter1 = zMin;
      diameter2 = zMax;
    }

    // Calculate the center of the initial sphere found by Ritter's algorithm
    var ritterCenter = fromPointsRitterCenter;
    ritterCenter.x = (diameter1.x + diameter2.x) * 0.5;
    ritterCenter.y = (diameter1.y + diameter2.y) * 0.5;
    ritterCenter.z = (diameter1.z + diameter2.z) * 0.5;

    // Calculate the radius of the initial sphere found by Ritter's algorithm
    var radiusSquared = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(diameter2, ritterCenter, fromPointsScratch)
    );
    var ritterRadius = Math.sqrt(radiusSquared);

    // Find the center of the sphere found using the Naive method.
    var minBoxPt = fromPointsMinBoxPt;
    minBoxPt.x = xMin.x;
    minBoxPt.y = yMin.y;
    minBoxPt.z = zMin.z;

    var maxBoxPt = fromPointsMaxBoxPt;
    maxBoxPt.x = xMax.x;
    maxBoxPt.y = yMax.y;
    maxBoxPt.z = zMax.z;

    var naiveCenter = Cartesian3.midpoint(
      minBoxPt,
      maxBoxPt,
      fromPointsNaiveCenterScratch
    );

    // Begin 2nd pass to find naive radius and modify the ritter sphere.
    var naiveRadius = 0;
    for (i = 0; i < numElements; i += stride) {
      currentPos.x = positions[i] + center.x;
      currentPos.y = positions[i + 1] + center.y;
      currentPos.z = positions[i + 2] + center.z;

      // Find the furthest point from the naive center to calculate the naive radius.
      var r = Cartesian3.magnitude(
        Cartesian3.subtract(currentPos, naiveCenter, fromPointsScratch)
      );
      if (r > naiveRadius) {
        naiveRadius = r;
      }

      // Make adjustments to the Ritter Sphere to include all points.
      var oldCenterToPointSquared = Cartesian3.magnitudeSquared(
        Cartesian3.subtract(currentPos, ritterCenter, fromPointsScratch)
      );
      if (oldCenterToPointSquared > radiusSquared) {
        var oldCenterToPoint = Math.sqrt(oldCenterToPointSquared);
        // Calculate new radius to include the point that lies outside
        ritterRadius = (ritterRadius + oldCenterToPoint) * 0.5;
        radiusSquared = ritterRadius * ritterRadius;
        // Calculate center of new Ritter sphere
        var oldToNew = oldCenterToPoint - ritterRadius;
        ritterCenter.x =
          (ritterRadius * ritterCenter.x + oldToNew * currentPos.x) /
          oldCenterToPoint;
        ritterCenter.y =
          (ritterRadius * ritterCenter.y + oldToNew * currentPos.y) /
          oldCenterToPoint;
        ritterCenter.z =
          (ritterRadius * ritterCenter.z + oldToNew * currentPos.z) /
          oldCenterToPoint;
      }
    }

    if (ritterRadius < naiveRadius) {
      Cartesian3.clone(ritterCenter, result.center);
      result.radius = ritterRadius;
    } else {
      Cartesian3.clone(naiveCenter, result.center);
      result.radius = naiveRadius;
    }

    return result;
  };

  /**
   * Computes a tight-fitting bounding sphere enclosing a list of EncodedCartesian3s, where the points are
   * stored in parallel flat arrays in X, Y, Z, order.  The bounding sphere is computed by running two
   * algorithms, a naive algorithm and Ritter's algorithm. The smaller of the two spheres is used to
   * ensure a tight fit.
   *
   * @param {Number[]} [positionsHigh] An array of high bits of the encoded cartesians that the bounding sphere will enclose.  Each point
   *        is formed from three elements in the array in the order X, Y, Z.
   * @param {Number[]} [positionsLow] An array of low bits of the encoded cartesians that the bounding sphere will enclose.  Each point
   *        is formed from three elements in the array in the order X, Y, Z.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if one was not provided.
   *
   * @see {@link http://blogs.agi.com/insight3d/index.php/2008/02/04/a-bounding/|Bounding Sphere computation article}
   */
  BoundingSphere.fromEncodedCartesianVertices = function (
    positionsHigh,
    positionsLow,
    result
  ) {
    if (!defined(result)) {
      result = new BoundingSphere();
    }

    if (
      !defined(positionsHigh) ||
      !defined(positionsLow) ||
      positionsHigh.length !== positionsLow.length ||
      positionsHigh.length === 0
    ) {
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      result.radius = 0.0;
      return result;
    }

    var currentPos = fromPointsCurrentPos;
    currentPos.x = positionsHigh[0] + positionsLow[0];
    currentPos.y = positionsHigh[1] + positionsLow[1];
    currentPos.z = positionsHigh[2] + positionsLow[2];

    var xMin = Cartesian3.clone(currentPos, fromPointsXMin);
    var yMin = Cartesian3.clone(currentPos, fromPointsYMin);
    var zMin = Cartesian3.clone(currentPos, fromPointsZMin);

    var xMax = Cartesian3.clone(currentPos, fromPointsXMax);
    var yMax = Cartesian3.clone(currentPos, fromPointsYMax);
    var zMax = Cartesian3.clone(currentPos, fromPointsZMax);

    var numElements = positionsHigh.length;
    var i;
    for (i = 0; i < numElements; i += 3) {
      var x = positionsHigh[i] + positionsLow[i];
      var y = positionsHigh[i + 1] + positionsLow[i + 1];
      var z = positionsHigh[i + 2] + positionsLow[i + 2];

      currentPos.x = x;
      currentPos.y = y;
      currentPos.z = z;

      // Store points containing the the smallest and largest components
      if (x < xMin.x) {
        Cartesian3.clone(currentPos, xMin);
      }

      if (x > xMax.x) {
        Cartesian3.clone(currentPos, xMax);
      }

      if (y < yMin.y) {
        Cartesian3.clone(currentPos, yMin);
      }

      if (y > yMax.y) {
        Cartesian3.clone(currentPos, yMax);
      }

      if (z < zMin.z) {
        Cartesian3.clone(currentPos, zMin);
      }

      if (z > zMax.z) {
        Cartesian3.clone(currentPos, zMax);
      }
    }

    // Compute x-, y-, and z-spans (Squared distances b/n each component's min. and max.).
    var xSpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(xMax, xMin, fromPointsScratch)
    );
    var ySpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(yMax, yMin, fromPointsScratch)
    );
    var zSpan = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(zMax, zMin, fromPointsScratch)
    );

    // Set the diameter endpoints to the largest span.
    var diameter1 = xMin;
    var diameter2 = xMax;
    var maxSpan = xSpan;
    if (ySpan > maxSpan) {
      maxSpan = ySpan;
      diameter1 = yMin;
      diameter2 = yMax;
    }
    if (zSpan > maxSpan) {
      maxSpan = zSpan;
      diameter1 = zMin;
      diameter2 = zMax;
    }

    // Calculate the center of the initial sphere found by Ritter's algorithm
    var ritterCenter = fromPointsRitterCenter;
    ritterCenter.x = (diameter1.x + diameter2.x) * 0.5;
    ritterCenter.y = (diameter1.y + diameter2.y) * 0.5;
    ritterCenter.z = (diameter1.z + diameter2.z) * 0.5;

    // Calculate the radius of the initial sphere found by Ritter's algorithm
    var radiusSquared = Cartesian3.magnitudeSquared(
      Cartesian3.subtract(diameter2, ritterCenter, fromPointsScratch)
    );
    var ritterRadius = Math.sqrt(radiusSquared);

    // Find the center of the sphere found using the Naive method.
    var minBoxPt = fromPointsMinBoxPt;
    minBoxPt.x = xMin.x;
    minBoxPt.y = yMin.y;
    minBoxPt.z = zMin.z;

    var maxBoxPt = fromPointsMaxBoxPt;
    maxBoxPt.x = xMax.x;
    maxBoxPt.y = yMax.y;
    maxBoxPt.z = zMax.z;

    var naiveCenter = Cartesian3.midpoint(
      minBoxPt,
      maxBoxPt,
      fromPointsNaiveCenterScratch
    );

    // Begin 2nd pass to find naive radius and modify the ritter sphere.
    var naiveRadius = 0;
    for (i = 0; i < numElements; i += 3) {
      currentPos.x = positionsHigh[i] + positionsLow[i];
      currentPos.y = positionsHigh[i + 1] + positionsLow[i + 1];
      currentPos.z = positionsHigh[i + 2] + positionsLow[i + 2];

      // Find the furthest point from the naive center to calculate the naive radius.
      var r = Cartesian3.magnitude(
        Cartesian3.subtract(currentPos, naiveCenter, fromPointsScratch)
      );
      if (r > naiveRadius) {
        naiveRadius = r;
      }

      // Make adjustments to the Ritter Sphere to include all points.
      var oldCenterToPointSquared = Cartesian3.magnitudeSquared(
        Cartesian3.subtract(currentPos, ritterCenter, fromPointsScratch)
      );
      if (oldCenterToPointSquared > radiusSquared) {
        var oldCenterToPoint = Math.sqrt(oldCenterToPointSquared);
        // Calculate new radius to include the point that lies outside
        ritterRadius = (ritterRadius + oldCenterToPoint) * 0.5;
        radiusSquared = ritterRadius * ritterRadius;
        // Calculate center of new Ritter sphere
        var oldToNew = oldCenterToPoint - ritterRadius;
        ritterCenter.x =
          (ritterRadius * ritterCenter.x + oldToNew * currentPos.x) /
          oldCenterToPoint;
        ritterCenter.y =
          (ritterRadius * ritterCenter.y + oldToNew * currentPos.y) /
          oldCenterToPoint;
        ritterCenter.z =
          (ritterRadius * ritterCenter.z + oldToNew * currentPos.z) /
          oldCenterToPoint;
      }
    }

    if (ritterRadius < naiveRadius) {
      Cartesian3.clone(ritterCenter, result.center);
      result.radius = ritterRadius;
    } else {
      Cartesian3.clone(naiveCenter, result.center);
      result.radius = naiveRadius;
    }

    return result;
  };

  /**
   * Computes a bounding sphere from the corner points of an axis-aligned bounding box.  The sphere
   * tighly and fully encompases the box.
   *
   * @param {Cartesian3} [corner] The minimum height over the rectangle.
   * @param {Cartesian3} [oppositeCorner] The maximum height over the rectangle.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   *
   * @example
   * // Create a bounding sphere around the unit cube
   * var sphere = Cesium.BoundingSphere.fromCornerPoints(new Cesium.Cartesian3(-0.5, -0.5, -0.5), new Cesium.Cartesian3(0.5, 0.5, 0.5));
   */
  BoundingSphere.fromCornerPoints = function (corner, oppositeCorner, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("corner", corner);
    Check.typeOf.object("oppositeCorner", oppositeCorner);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    var center = Cartesian3.midpoint(corner, oppositeCorner, result.center);
    result.radius = Cartesian3.distance(center, oppositeCorner);
    return result;
  };

  /**
   * Creates a bounding sphere encompassing an ellipsoid.
   *
   * @param {Ellipsoid} ellipsoid The ellipsoid around which to create a bounding sphere.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   *
   * @example
   * var boundingSphere = Cesium.BoundingSphere.fromEllipsoid(ellipsoid);
   */
  BoundingSphere.fromEllipsoid = function (ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("ellipsoid", ellipsoid);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    Cartesian3.clone(Cartesian3.ZERO, result.center);
    result.radius = ellipsoid.maximumRadius;
    return result;
  };

  var fromBoundingSpheresScratch = new Cartesian3();

  /**
   * Computes a tight-fitting bounding sphere enclosing the provided array of bounding spheres.
   *
   * @param {BoundingSphere[]} [boundingSpheres] The array of bounding spheres.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.fromBoundingSpheres = function (boundingSpheres, result) {
    if (!defined(result)) {
      result = new BoundingSphere();
    }

    if (!defined(boundingSpheres) || boundingSpheres.length === 0) {
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      result.radius = 0.0;
      return result;
    }

    var length = boundingSpheres.length;
    if (length === 1) {
      return BoundingSphere.clone(boundingSpheres[0], result);
    }

    if (length === 2) {
      return BoundingSphere.union(boundingSpheres[0], boundingSpheres[1], result);
    }

    var positions = [];
    var i;
    for (i = 0; i < length; i++) {
      positions.push(boundingSpheres[i].center);
    }

    result = BoundingSphere.fromPoints(positions, result);

    var center = result.center;
    var radius = result.radius;
    for (i = 0; i < length; i++) {
      var tmp = boundingSpheres[i];
      radius = Math.max(
        radius,
        Cartesian3.distance(center, tmp.center, fromBoundingSpheresScratch) +
          tmp.radius
      );
    }
    result.radius = radius;

    return result;
  };

  var fromOrientedBoundingBoxScratchU = new Cartesian3();
  var fromOrientedBoundingBoxScratchV = new Cartesian3();
  var fromOrientedBoundingBoxScratchW = new Cartesian3();

  /**
   * Computes a tight-fitting bounding sphere enclosing the provided oriented bounding box.
   *
   * @param {OrientedBoundingBox} orientedBoundingBox The oriented bounding box.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.fromOrientedBoundingBox = function (
    orientedBoundingBox,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("orientedBoundingBox", orientedBoundingBox);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    var halfAxes = orientedBoundingBox.halfAxes;
    var u = Matrix3.getColumn(halfAxes, 0, fromOrientedBoundingBoxScratchU);
    var v = Matrix3.getColumn(halfAxes, 1, fromOrientedBoundingBoxScratchV);
    var w = Matrix3.getColumn(halfAxes, 2, fromOrientedBoundingBoxScratchW);

    Cartesian3.add(u, v, u);
    Cartesian3.add(u, w, u);

    result.center = Cartesian3.clone(orientedBoundingBox.center, result.center);
    result.radius = Cartesian3.magnitude(u);

    return result;
  };

  /**
   * Duplicates a BoundingSphere instance.
   *
   * @param {BoundingSphere} sphere The bounding sphere to duplicate.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided. (Returns undefined if sphere is undefined)
   */
  BoundingSphere.clone = function (sphere, result) {
    if (!defined(sphere)) {
      return undefined;
    }

    if (!defined(result)) {
      return new BoundingSphere(sphere.center, sphere.radius);
    }

    result.center = Cartesian3.clone(sphere.center, result.center);
    result.radius = sphere.radius;
    return result;
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  BoundingSphere.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {BoundingSphere} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  BoundingSphere.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var center = value.center;
    array[startingIndex++] = center.x;
    array[startingIndex++] = center.y;
    array[startingIndex++] = center.z;
    array[startingIndex] = value.radius;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {BoundingSphere} [result] The object into which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if one was not provided.
   */
  BoundingSphere.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    var center = result.center;
    center.x = array[startingIndex++];
    center.y = array[startingIndex++];
    center.z = array[startingIndex++];
    result.radius = array[startingIndex];
    return result;
  };

  var unionScratch = new Cartesian3();
  var unionScratchCenter = new Cartesian3();
  /**
   * Computes a bounding sphere that contains both the left and right bounding spheres.
   *
   * @param {BoundingSphere} left A sphere to enclose in a bounding sphere.
   * @param {BoundingSphere} right A sphere to enclose in a bounding sphere.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.union = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    var leftCenter = left.center;
    var leftRadius = left.radius;
    var rightCenter = right.center;
    var rightRadius = right.radius;

    var toRightCenter = Cartesian3.subtract(
      rightCenter,
      leftCenter,
      unionScratch
    );
    var centerSeparation = Cartesian3.magnitude(toRightCenter);

    if (leftRadius >= centerSeparation + rightRadius) {
      // Left sphere wins.
      left.clone(result);
      return result;
    }

    if (rightRadius >= centerSeparation + leftRadius) {
      // Right sphere wins.
      right.clone(result);
      return result;
    }

    // There are two tangent points, one on far side of each sphere.
    var halfDistanceBetweenTangentPoints =
      (leftRadius + centerSeparation + rightRadius) * 0.5;

    // Compute the center point halfway between the two tangent points.
    var center = Cartesian3.multiplyByScalar(
      toRightCenter,
      (-leftRadius + halfDistanceBetweenTangentPoints) / centerSeparation,
      unionScratchCenter
    );
    Cartesian3.add(center, leftCenter, center);
    Cartesian3.clone(center, result.center);
    result.radius = halfDistanceBetweenTangentPoints;

    return result;
  };

  var expandScratch = new Cartesian3();
  /**
   * Computes a bounding sphere by enlarging the provided sphere to contain the provided point.
   *
   * @param {BoundingSphere} sphere A sphere to expand.
   * @param {Cartesian3} point A point to enclose in a bounding sphere.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.expand = function (sphere, point, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("point", point);
    //>>includeEnd('debug');

    result = BoundingSphere.clone(sphere, result);

    var radius = Cartesian3.magnitude(
      Cartesian3.subtract(point, result.center, expandScratch)
    );
    if (radius > result.radius) {
      result.radius = radius;
    }

    return result;
  };

  /**
   * Determines which side of a plane a sphere is located.
   *
   * @param {BoundingSphere} sphere The bounding sphere to test.
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire sphere is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire sphere is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the sphere
   *                      intersects the plane.
   */
  BoundingSphere.intersectPlane = function (sphere, plane) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("plane", plane);
    //>>includeEnd('debug');

    var center = sphere.center;
    var radius = sphere.radius;
    var normal = plane.normal;
    var distanceToPlane = Cartesian3.dot(normal, center) + plane.distance;

    if (distanceToPlane < -radius) {
      // The center point is negative side of the plane normal
      return Intersect$1.OUTSIDE;
    } else if (distanceToPlane < radius) {
      // The center point is positive side of the plane, but radius extends beyond it; partial overlap
      return Intersect$1.INTERSECTING;
    }
    return Intersect$1.INSIDE;
  };

  /**
   * Applies a 4x4 affine transformation matrix to a bounding sphere.
   *
   * @param {BoundingSphere} sphere The bounding sphere to apply the transformation to.
   * @param {Matrix4} transform The transformation matrix to apply to the bounding sphere.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.transform = function (sphere, transform, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("transform", transform);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    result.center = Matrix4.multiplyByPoint(
      transform,
      sphere.center,
      result.center
    );
    result.radius = Matrix4.getMaximumScale(transform) * sphere.radius;

    return result;
  };

  var distanceSquaredToScratch = new Cartesian3();

  /**
   * Computes the estimated distance squared from the closest point on a bounding sphere to a point.
   *
   * @param {BoundingSphere} sphere The sphere.
   * @param {Cartesian3} cartesian The point
   * @returns {Number} The estimated distance squared from the bounding sphere to the point.
   *
   * @example
   * // Sort bounding spheres from back to front
   * spheres.sort(function(a, b) {
   *     return Cesium.BoundingSphere.distanceSquaredTo(b, camera.positionWC) - Cesium.BoundingSphere.distanceSquaredTo(a, camera.positionWC);
   * });
   */
  BoundingSphere.distanceSquaredTo = function (sphere, cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    var diff = Cartesian3.subtract(
      sphere.center,
      cartesian,
      distanceSquaredToScratch
    );
    return Cartesian3.magnitudeSquared(diff) - sphere.radius * sphere.radius;
  };

  /**
   * Applies a 4x4 affine transformation matrix to a bounding sphere where there is no scale
   * The transformation matrix is not verified to have a uniform scale of 1.
   * This method is faster than computing the general bounding sphere transform using {@link BoundingSphere.transform}.
   *
   * @param {BoundingSphere} sphere The bounding sphere to apply the transformation to.
   * @param {Matrix4} transform The transformation matrix to apply to the bounding sphere.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   *
   * @example
   * var modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(positionOnEllipsoid);
   * var boundingSphere = new Cesium.BoundingSphere();
   * var newBoundingSphere = Cesium.BoundingSphere.transformWithoutScale(boundingSphere, modelMatrix);
   */
  BoundingSphere.transformWithoutScale = function (sphere, transform, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("transform", transform);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingSphere();
    }

    result.center = Matrix4.multiplyByPoint(
      transform,
      sphere.center,
      result.center
    );
    result.radius = sphere.radius;

    return result;
  };

  var scratchCartesian3 = new Cartesian3();
  /**
   * The distances calculated by the vector from the center of the bounding sphere to position projected onto direction
   * plus/minus the radius of the bounding sphere.
   * <br>
   * If you imagine the infinite number of planes with normal direction, this computes the smallest distance to the
   * closest and farthest planes from position that intersect the bounding sphere.
   *
   * @param {BoundingSphere} sphere The bounding sphere to calculate the distance to.
   * @param {Cartesian3} position The position to calculate the distance from.
   * @param {Cartesian3} direction The direction from position.
   * @param {Interval} [result] A Interval to store the nearest and farthest distances.
   * @returns {Interval} The nearest and farthest distances on the bounding sphere from position in direction.
   */
  BoundingSphere.computePlaneDistances = function (
    sphere,
    position,
    direction,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("position", position);
    Check.typeOf.object("direction", direction);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Interval();
    }

    var toCenter = Cartesian3.subtract(
      sphere.center,
      position,
      scratchCartesian3
    );
    var mag = Cartesian3.dot(direction, toCenter);

    result.start = mag - sphere.radius;
    result.stop = mag + sphere.radius;
    return result;
  };

  var projectTo2DNormalScratch = new Cartesian3();
  var projectTo2DEastScratch = new Cartesian3();
  var projectTo2DNorthScratch = new Cartesian3();
  var projectTo2DWestScratch = new Cartesian3();
  var projectTo2DSouthScratch = new Cartesian3();
  var projectTo2DCartographicScratch = new Cartographic();
  var projectTo2DPositionsScratch = new Array(8);
  for (var n = 0; n < 8; ++n) {
    projectTo2DPositionsScratch[n] = new Cartesian3();
  }

  var projectTo2DProjection = new GeographicProjection();
  /**
   * Creates a bounding sphere in 2D from a bounding sphere in 3D world coordinates.
   *
   * @param {BoundingSphere} sphere The bounding sphere to transform to 2D.
   * @param {Object} [projection=GeographicProjection] The projection to 2D.
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.projectTo2D = function (sphere, projection, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    //>>includeEnd('debug');

    projection = defaultValue(projection, projectTo2DProjection);

    var ellipsoid = projection.ellipsoid;
    var center = sphere.center;
    var radius = sphere.radius;

    var normal;
    if (Cartesian3.equals(center, Cartesian3.ZERO)) {
      // Bounding sphere is at the center. The geodetic surface normal is not
      // defined here so pick the x-axis as a fallback.
      normal = Cartesian3.clone(Cartesian3.UNIT_X, projectTo2DNormalScratch);
    } else {
      normal = ellipsoid.geodeticSurfaceNormal(center, projectTo2DNormalScratch);
    }
    var east = Cartesian3.cross(
      Cartesian3.UNIT_Z,
      normal,
      projectTo2DEastScratch
    );
    Cartesian3.normalize(east, east);
    var north = Cartesian3.cross(normal, east, projectTo2DNorthScratch);
    Cartesian3.normalize(north, north);

    Cartesian3.multiplyByScalar(normal, radius, normal);
    Cartesian3.multiplyByScalar(north, radius, north);
    Cartesian3.multiplyByScalar(east, radius, east);

    var south = Cartesian3.negate(north, projectTo2DSouthScratch);
    var west = Cartesian3.negate(east, projectTo2DWestScratch);

    var positions = projectTo2DPositionsScratch;

    // top NE corner
    var corner = positions[0];
    Cartesian3.add(normal, north, corner);
    Cartesian3.add(corner, east, corner);

    // top NW corner
    corner = positions[1];
    Cartesian3.add(normal, north, corner);
    Cartesian3.add(corner, west, corner);

    // top SW corner
    corner = positions[2];
    Cartesian3.add(normal, south, corner);
    Cartesian3.add(corner, west, corner);

    // top SE corner
    corner = positions[3];
    Cartesian3.add(normal, south, corner);
    Cartesian3.add(corner, east, corner);

    Cartesian3.negate(normal, normal);

    // bottom NE corner
    corner = positions[4];
    Cartesian3.add(normal, north, corner);
    Cartesian3.add(corner, east, corner);

    // bottom NW corner
    corner = positions[5];
    Cartesian3.add(normal, north, corner);
    Cartesian3.add(corner, west, corner);

    // bottom SW corner
    corner = positions[6];
    Cartesian3.add(normal, south, corner);
    Cartesian3.add(corner, west, corner);

    // bottom SE corner
    corner = positions[7];
    Cartesian3.add(normal, south, corner);
    Cartesian3.add(corner, east, corner);

    var length = positions.length;
    for (var i = 0; i < length; ++i) {
      var position = positions[i];
      Cartesian3.add(center, position, position);
      var cartographic = ellipsoid.cartesianToCartographic(
        position,
        projectTo2DCartographicScratch
      );
      projection.project(cartographic, position);
    }

    result = BoundingSphere.fromPoints(positions, result);

    // swizzle center components
    center = result.center;
    var x = center.x;
    var y = center.y;
    var z = center.z;
    center.x = z;
    center.y = x;
    center.z = y;

    return result;
  };

  /**
   * Determines whether or not a sphere is hidden from view by the occluder.
   *
   * @param {BoundingSphere} sphere The bounding sphere surrounding the occludee object.
   * @param {Occluder} occluder The occluder.
   * @returns {Boolean} <code>true</code> if the sphere is not visible; otherwise <code>false</code>.
   */
  BoundingSphere.isOccluded = function (sphere, occluder) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("sphere", sphere);
    Check.typeOf.object("occluder", occluder);
    //>>includeEnd('debug');
    return !occluder.isBoundingSphereVisible(sphere);
  };

  /**
   * Compares the provided BoundingSphere componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {BoundingSphere} [left] The first BoundingSphere.
   * @param {BoundingSphere} [right] The second BoundingSphere.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  BoundingSphere.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Cartesian3.equals(left.center, right.center) &&
        left.radius === right.radius)
    );
  };

  /**
   * Determines which side of a plane the sphere is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire sphere is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire sphere is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the sphere
   *                      intersects the plane.
   */
  BoundingSphere.prototype.intersectPlane = function (plane) {
    return BoundingSphere.intersectPlane(this, plane);
  };

  /**
   * Computes the estimated distance squared from the closest point on a bounding sphere to a point.
   *
   * @param {Cartesian3} cartesian The point
   * @returns {Number} The estimated distance squared from the bounding sphere to the point.
   *
   * @example
   * // Sort bounding spheres from back to front
   * spheres.sort(function(a, b) {
   *     return b.distanceSquaredTo(camera.positionWC) - a.distanceSquaredTo(camera.positionWC);
   * });
   */
  BoundingSphere.prototype.distanceSquaredTo = function (cartesian) {
    return BoundingSphere.distanceSquaredTo(this, cartesian);
  };

  /**
   * The distances calculated by the vector from the center of the bounding sphere to position projected onto direction
   * plus/minus the radius of the bounding sphere.
   * <br>
   * If you imagine the infinite number of planes with normal direction, this computes the smallest distance to the
   * closest and farthest planes from position that intersect the bounding sphere.
   *
   * @param {Cartesian3} position The position to calculate the distance from.
   * @param {Cartesian3} direction The direction from position.
   * @param {Interval} [result] A Interval to store the nearest and farthest distances.
   * @returns {Interval} The nearest and farthest distances on the bounding sphere from position in direction.
   */
  BoundingSphere.prototype.computePlaneDistances = function (
    position,
    direction,
    result
  ) {
    return BoundingSphere.computePlaneDistances(
      this,
      position,
      direction,
      result
    );
  };

  /**
   * Determines whether or not a sphere is hidden from view by the occluder.
   *
   * @param {Occluder} occluder The occluder.
   * @returns {Boolean} <code>true</code> if the sphere is not visible; otherwise <code>false</code>.
   */
  BoundingSphere.prototype.isOccluded = function (occluder) {
    return BoundingSphere.isOccluded(this, occluder);
  };

  /**
   * Compares this BoundingSphere against the provided BoundingSphere componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {BoundingSphere} [right] The right hand side BoundingSphere.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  BoundingSphere.prototype.equals = function (right) {
    return BoundingSphere.equals(this, right);
  };

  /**
   * Duplicates this BoundingSphere instance.
   *
   * @param {BoundingSphere} [result] The object onto which to store the result.
   * @returns {BoundingSphere} The modified result parameter or a new BoundingSphere instance if none was provided.
   */
  BoundingSphere.prototype.clone = function (result) {
    return BoundingSphere.clone(this, result);
  };

  /**
   * Computes the radius of the BoundingSphere.
   * @returns {Number} The radius of the BoundingSphere.
   */
  BoundingSphere.prototype.volume = function () {
    var radius = this.radius;
    return volumeConstant * radius * radius * radius;
  };

  /**
   * @license
   *
   * Grauw URI utilities
   *
   * See: http://hg.grauw.nl/grauw-lib/file/tip/src/uri.js
   *
   * @author Laurens Holst (http://www.grauw.nl/)
   *
   *   Copyright 2012 Laurens Holst
   *
   *   Licensed under the Apache License, Version 2.0 (the "License");
   *   you may not use this file except in compliance with the License.
   *   You may obtain a copy of the License at
   *
   *       http://www.apache.org/licenses/LICENSE-2.0
   *
   *   Unless required by applicable law or agreed to in writing, software
   *   distributed under the License is distributed on an "AS IS" BASIS,
   *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *   See the License for the specific language governing permissions and
   *   limitations under the License.
   *
   */

  	/**
  	 * Constructs a URI object.
  	 * @constructor
  	 * @class Implementation of URI parsing and base URI resolving algorithm in RFC 3986.
  	 * @param {string|URI} uri A string or URI object to create the object from.
  	 */
  	function URI(uri) {
  		if (uri instanceof URI) {  // copy constructor
  			this.scheme = uri.scheme;
  			this.authority = uri.authority;
  			this.path = uri.path;
  			this.query = uri.query;
  			this.fragment = uri.fragment;
  		} else if (uri) {  // uri is URI string or cast to string
  			var c = parseRegex.exec(uri);
  			this.scheme = c[1];
  			this.authority = c[2];
  			this.path = c[3];
  			this.query = c[4];
  			this.fragment = c[5];
  		}
  	}
  	// Initial values on the prototype
  	URI.prototype.scheme    = null;
  	URI.prototype.authority = null;
  	URI.prototype.path      = '';
  	URI.prototype.query     = null;
  	URI.prototype.fragment  = null;

  	// Regular expression from RFC 3986 appendix B
  	var parseRegex = new RegExp('^(?:([^:/?#]+):)?(?://([^/?#]*))?([^?#]*)(?:\\?([^#]*))?(?:#(.*))?$');

  	/**
  	 * Returns the scheme part of the URI.
  	 * In "http://example.com:80/a/b?x#y" this is "http".
  	 */
  	URI.prototype.getScheme = function() {
  		return this.scheme;
  	};

  	/**
  	 * Returns the authority part of the URI.
  	 * In "http://example.com:80/a/b?x#y" this is "example.com:80".
  	 */
  	URI.prototype.getAuthority = function() {
  		return this.authority;
  	};

  	/**
  	 * Returns the path part of the URI.
  	 * In "http://example.com:80/a/b?x#y" this is "/a/b".
  	 * In "mailto:mike@example.com" this is "mike@example.com".
  	 */
  	URI.prototype.getPath = function() {
  		return this.path;
  	};

  	/**
  	 * Returns the query part of the URI.
  	 * In "http://example.com:80/a/b?x#y" this is "x".
  	 */
  	URI.prototype.getQuery = function() {
  		return this.query;
  	};

  	/**
  	 * Returns the fragment part of the URI.
  	 * In "http://example.com:80/a/b?x#y" this is "y".
  	 */
  	URI.prototype.getFragment = function() {
  		return this.fragment;
  	};

  	/**
  	 * Tests whether the URI is an absolute URI.
  	 * See RFC 3986 section 4.3.
  	 */
  	URI.prototype.isAbsolute = function() {
  		return !!this.scheme && !this.fragment;
  	};

  	///**
  	//* Extensive validation of the URI against the ABNF in RFC 3986
  	//*/
  	//URI.prototype.validate

  	/**
  	 * Tests whether the URI is a same-document reference.
  	 * See RFC 3986 section 4.4.
  	 *
  	 * To perform more thorough comparison, you can normalise the URI objects.
  	 */
  	URI.prototype.isSameDocumentAs = function(uri) {
  		return uri.scheme == this.scheme &&
  		    uri.authority == this.authority &&
  		         uri.path == this.path &&
  		        uri.query == this.query;
  	};

  	/**
  	 * Simple String Comparison of two URIs.
  	 * See RFC 3986 section 6.2.1.
  	 *
  	 * To perform more thorough comparison, you can normalise the URI objects.
  	 */
  	URI.prototype.equals = function(uri) {
  		return this.isSameDocumentAs(uri) && uri.fragment == this.fragment;
  	};

  	/**
  	 * Normalizes the URI using syntax-based normalization.
  	 * This includes case normalization, percent-encoding normalization and path segment normalization.
  	 * XXX: Percent-encoding normalization does not escape characters that need to be escaped.
  	 *      (Although that would not be a valid URI in the first place. See validate().)
  	 * See RFC 3986 section 6.2.2.
  	 */
  	URI.prototype.normalize = function() {
  		this.removeDotSegments();
  		if (this.scheme)
  			this.scheme = this.scheme.toLowerCase();
  		if (this.authority)
  			this.authority = this.authority.replace(authorityRegex, replaceAuthority).
  									replace(caseRegex, replaceCase);
  		if (this.path)
  			this.path = this.path.replace(caseRegex, replaceCase);
  		if (this.query)
  			this.query = this.query.replace(caseRegex, replaceCase);
  		if (this.fragment)
  			this.fragment = this.fragment.replace(caseRegex, replaceCase);
  	};

  	var caseRegex = /%[0-9a-z]{2}/gi;
  	var percentRegex = /[a-zA-Z0-9\-\._~]/;
  	var authorityRegex = /(.*@)?([^@:]*)(:.*)?/;

  	function replaceCase(str) {
  		var dec = unescape(str);
  		return percentRegex.test(dec) ? dec : str.toUpperCase();
  	}

  	function replaceAuthority(str, p1, p2, p3) {
  		return (p1 || '') + p2.toLowerCase() + (p3 || '');
  	}

  	/**
  	 * Resolve a relative URI (this) against a base URI.
  	 * The base URI must be an absolute URI.
  	 * See RFC 3986 section 5.2
  	 */
  	URI.prototype.resolve = function(baseURI) {
  		var uri = new URI();
  		if (this.scheme) {
  			uri.scheme = this.scheme;
  			uri.authority = this.authority;
  			uri.path = this.path;
  			uri.query = this.query;
  		} else {
  			uri.scheme = baseURI.scheme;
  			if (this.authority) {
  				uri.authority = this.authority;
  				uri.path = this.path;
  				uri.query = this.query;
  			} else {
  				uri.authority = baseURI.authority;
  				if (this.path == '') {
  					uri.path = baseURI.path;
  					uri.query = this.query || baseURI.query;
  				} else {
  					if (this.path.charAt(0) == '/') {
  						uri.path = this.path;
  						uri.removeDotSegments();
  					} else {
  						if (baseURI.authority && baseURI.path == '') {
  							uri.path = '/' + this.path;
  						} else {
  							uri.path = baseURI.path.substring(0, baseURI.path.lastIndexOf('/') + 1) + this.path;
  						}
  						uri.removeDotSegments();
  					}
  					uri.query = this.query;
  				}
  			}
  		}
  		uri.fragment = this.fragment;
  		return uri;
  	};

  	/**
  	 * Remove dot segments from path.
  	 * See RFC 3986 section 5.2.4
  	 * @private
  	 */
  	URI.prototype.removeDotSegments = function() {
  		var input = this.path.split('/'),
  			output = [],
  			segment,
  			absPath = input[0] == '';
  		if (absPath)
  			input.shift();
  		var sFirst = input[0] == '' ? input.shift() : null;
  		while (input.length) {
  			segment = input.shift();
  			if (segment == '..') {
  				output.pop();
  			} else if (segment != '.') {
  				output.push(segment);
  			}
  		}
  		if (segment == '.' || segment == '..')
  			output.push('');
  		if (absPath)
  			output.unshift('');
  		this.path = output.join('/');
  	};

  	// We don't like this function because it builds up a cache that is never cleared.
  //	/**
  //	 * Resolves a relative URI against an absolute base URI.
  //	 * Convenience method.
  //	 * @param {String} uri the relative URI to resolve
  //	 * @param {String} baseURI the base URI (must be absolute) to resolve against
  //	 */
  //	URI.resolve = function(sURI, sBaseURI) {
  //		var uri = cache[sURI] || (cache[sURI] = new URI(sURI));
  //		var baseURI = cache[sBaseURI] || (cache[sBaseURI] = new URI(sBaseURI));
  //		return uri.resolve(baseURI).toString();
  //	};

  //	var cache = {};

  	/**
  	 * Serialises the URI to a string.
  	 */
  	URI.prototype.toString = function() {
  		var result = '';
  		if (this.scheme)
  			result += this.scheme + ':';
  		if (this.authority)
  			result += '//' + this.authority;
  		result += this.path;
  		if (this.query)
  			result += '?' + this.query;
  		if (this.fragment)
  			result += '#' + this.fragment;
  		return result;
  	};

  /**
   * Given a relative Uri and a base Uri, returns the absolute Uri of the relative Uri.
   * @function
   *
   * @param {String} relative The relative Uri.
   * @param {String} [base] The base Uri.
   * @returns {String} The absolute Uri of the given relative Uri.
   *
   * @example
   * //absolute Uri will be "https://test.com/awesome.png";
   * var absoluteUri = Cesium.getAbsoluteUri('awesome.png', 'https://test.com');
   */
  function getAbsoluteUri(relative, base) {
    var documentObject;
    if (typeof document !== "undefined") {
      documentObject = document;
    }

    return getAbsoluteUri._implementation(relative, base, documentObject);
  }

  getAbsoluteUri._implementation = function (relative, base, documentObject) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(relative)) {
      throw new DeveloperError("relative uri is required.");
    }
    //>>includeEnd('debug');

    if (!defined(base)) {
      if (typeof documentObject === "undefined") {
        return relative;
      }
      base = defaultValue(documentObject.baseURI, documentObject.location.href);
    }

    var baseUri = new URI(base);
    var relativeUri = new URI(relative);
    return relativeUri.resolve(baseUri).toString();
  };

  /**
    @license
    when.js - https://github.com/cujojs/when

    MIT License (c) copyright B Cavalier & J Hann

   * A lightweight CommonJS Promises/A and when() implementation
   * when is part of the cujo.js family of libraries (http://cujojs.com/)
   *
   * Licensed under the MIT License at:
   * http://www.opensource.org/licenses/mit-license.php
   *
   * @version 1.7.1
   */

  	var reduceArray, slice, undef;

  	//
  	// Public API
  	//

  	when.defer     = defer;     // Create a deferred
  	when.resolve   = resolve;   // Create a resolved promise
  	when.reject    = reject;    // Create a rejected promise

  	when.join      = join;      // Join 2 or more promises

  	when.all       = all;       // Resolve a list of promises
  	when.map       = map;       // Array.map() for promises
  	when.reduce    = reduce;    // Array.reduce() for promises

  	when.any       = any;       // One-winner race
  	when.some      = some;      // Multi-winner race

  	when.chain     = chain;     // Make a promise trigger another resolver

  	when.isPromise = isPromise; // Determine if a thing is a promise

  	/**
  	 * Register an observer for a promise or immediate value.
  	 *
  	 * @param {*} promiseOrValue
  	 * @param {function?} [onFulfilled] callback to be called when promiseOrValue is
  	 *   successfully fulfilled.  If promiseOrValue is an immediate value, callback
  	 *   will be invoked immediately.
  	 * @param {function?} [onRejected] callback to be called when promiseOrValue is
  	 *   rejected.
  	 * @param {function?} [onProgress] callback to be called when progress updates
  	 *   are issued for promiseOrValue.
  	 * @returns {Promise} a new {@link Promise} that will complete with the return
  	 *   value of callback or errback or the completion value of promiseOrValue if
  	 *   callback and/or errback is not supplied.
  	 */
  	function when(promiseOrValue, onFulfilled, onRejected, onProgress) {
  		// Get a trusted promise for the input promiseOrValue, and then
  		// register promise handlers
  		return resolve(promiseOrValue).then(onFulfilled, onRejected, onProgress);
  	}

  	/**
  	 * Returns promiseOrValue if promiseOrValue is a {@link Promise}, a new Promise if
  	 * promiseOrValue is a foreign promise, or a new, already-fulfilled {@link Promise}
  	 * whose value is promiseOrValue if promiseOrValue is an immediate value.
  	 *
  	 * @param {*} promiseOrValue
  	 * @returns Guaranteed to return a trusted Promise.  If promiseOrValue is a when.js {@link Promise}
  	 *   returns promiseOrValue, otherwise, returns a new, already-resolved, when.js {@link Promise}
  	 *   whose resolution value is:
  	 *   * the resolution value of promiseOrValue if it's a foreign promise, or
  	 *   * promiseOrValue if it's a value
  	 */
  	function resolve(promiseOrValue) {
  		var promise, deferred;

  		if(promiseOrValue instanceof Promise$1) {
  			// It's a when.js promise, so we trust it
  			promise = promiseOrValue;

  		} else {
  			// It's not a when.js promise. See if it's a foreign promise or a value.
  			if(isPromise(promiseOrValue)) {
  				// It's a thenable, but we don't know where it came from, so don't trust
  				// its implementation entirely.  Introduce a trusted middleman when.js promise
  				deferred = defer();

  				// IMPORTANT: This is the only place when.js should ever call .then() on an
  				// untrusted promise. Don't expose the return value to the untrusted promise
  				promiseOrValue.then(
  					function(value)  { deferred.resolve(value); },
  					function(reason) { deferred.reject(reason); },
  					function(update) { deferred.progress(update); }
  				);

  				promise = deferred.promise;

  			} else {
  				// It's a value, not a promise.  Create a resolved promise for it.
  				promise = fulfilled(promiseOrValue);
  			}
  		}

  		return promise;
  	}

  	/**
  	 * Returns a rejected promise for the supplied promiseOrValue.  The returned
  	 * promise will be rejected with:
  	 * - promiseOrValue, if it is a value, or
  	 * - if promiseOrValue is a promise
  	 *   - promiseOrValue's value after it is fulfilled
  	 *   - promiseOrValue's reason after it is rejected
  	 * @param {*} promiseOrValue the rejected value of the returned {@link Promise}
  	 * @returns {Promise} rejected {@link Promise}
  	 */
  	function reject(promiseOrValue) {
  		return when(promiseOrValue, rejected);
  	}

  	/**
  	 * Trusted Promise constructor.  A Promise created from this constructor is
  	 * a trusted when.js promise.  Any other duck-typed promise is considered
  	 * untrusted.
  	 * @constructor
  	 * @name Promise
  	 */
  	function Promise$1(then) {
  		this.then = then;
  	}

  	Promise$1.prototype = {
  		/**
  		 * Register a callback that will be called when a promise is
  		 * fulfilled or rejected.  Optionally also register a progress handler.
  		 * Shortcut for .then(onFulfilledOrRejected, onFulfilledOrRejected, onProgress)
  		 * @param {function?} [onFulfilledOrRejected]
  		 * @param {function?} [onProgress]
  		 * @returns {Promise}
  		 */
  		always: function(onFulfilledOrRejected, onProgress) {
  			return this.then(onFulfilledOrRejected, onFulfilledOrRejected, onProgress);
  		},

  		/**
  		 * Register a rejection handler.  Shortcut for .then(undefined, onRejected)
  		 * @param {function?} onRejected
  		 * @returns {Promise}
  		 */
  		otherwise: function(onRejected) {
  			return this.then(undef, onRejected);
  		},

  		/**
  		 * Shortcut for .then(function() { return value; })
  		 * @param  {*} value
  		 * @returns {Promise} a promise that:
  		 *  - is fulfilled if value is not a promise, or
  		 *  - if value is a promise, will fulfill with its value, or reject
  		 *    with its reason.
  		 */
  		yield: function(value) {
  			return this.then(function() {
  				return value;
  			});
  		},

  		/**
  		 * Assumes that this promise will fulfill with an array, and arranges
  		 * for the onFulfilled to be called with the array as its argument list
  		 * i.e. onFulfilled.spread(undefined, array).
  		 * @param {function} onFulfilled function to receive spread arguments
  		 * @returns {Promise}
  		 */
  		spread: function(onFulfilled) {
  			return this.then(function(array) {
  				// array may contain promises, so resolve its contents.
  				return all(array, function(array) {
  					return onFulfilled.apply(undef, array);
  				});
  			});
  		}
  	};

  	/**
  	 * Create an already-resolved promise for the supplied value
  	 * @private
  	 *
  	 * @param {*} value
  	 * @returns {Promise} fulfilled promise
  	 */
  	function fulfilled(value) {
  		var p = new Promise$1(function(onFulfilled) {
  			// TODO: Promises/A+ check typeof onFulfilled
  			try {
  				return resolve(onFulfilled ? onFulfilled(value) : value);
  			} catch(e) {
  				return rejected(e);
  			}
  		});

  		return p;
  	}

  	/**
  	 * Create an already-rejected {@link Promise} with the supplied
  	 * rejection reason.
  	 * @private
  	 *
  	 * @param {*} reason
  	 * @returns {Promise} rejected promise
  	 */
  	function rejected(reason) {
  		var p = new Promise$1(function(_, onRejected) {
  			// TODO: Promises/A+ check typeof onRejected
  			try {
  				return onRejected ? resolve(onRejected(reason)) : rejected(reason);
  			} catch(e) {
  				return rejected(e);
  			}
  		});

  		return p;
  	}

  	/**
  	 * Creates a new, Deferred with fully isolated resolver and promise parts,
  	 * either or both of which may be given out safely to consumers.
  	 * The Deferred itself has the full API: resolve, reject, progress, and
  	 * then. The resolver has resolve, reject, and progress.  The promise
  	 * only has then.
  	 *
  	 * @returns {Deferred}
  	 */
  	function defer() {
  		var deferred, promise, handlers, progressHandlers,
  			_then, _progress, _resolve;

  		/**
  		 * The promise for the new deferred
  		 * @type {Promise}
  		 */
  		promise = new Promise$1(then);

  		/**
  		 * The full Deferred object, with {@link Promise} and {@link Resolver} parts
  		 * @class Deferred
  		 * @name Deferred
  		 */
  		deferred = {
  			then:     then, // DEPRECATED: use deferred.promise.then
  			resolve:  promiseResolve,
  			reject:   promiseReject,
  			// TODO: Consider renaming progress() to notify()
  			progress: promiseProgress,

  			promise:  promise,

  			resolver: {
  				resolve:  promiseResolve,
  				reject:   promiseReject,
  				progress: promiseProgress
  			}
  		};

  		handlers = [];
  		progressHandlers = [];

  		/**
  		 * Pre-resolution then() that adds the supplied callback, errback, and progback
  		 * functions to the registered listeners
  		 * @private
  		 *
  		 * @param {function?} [onFulfilled] resolution handler
  		 * @param {function?} [onRejected] rejection handler
  		 * @param {function?} [onProgress] progress handler
  		 */
  		_then = function(onFulfilled, onRejected, onProgress) {
  			// TODO: Promises/A+ check typeof onFulfilled, onRejected, onProgress
  			var deferred, progressHandler;

  			deferred = defer();

  			progressHandler = typeof onProgress === 'function'
  				? function(update) {
  					try {
  						// Allow progress handler to transform progress event
  						deferred.progress(onProgress(update));
  					} catch(e) {
  						// Use caught value as progress
  						deferred.progress(e);
  					}
  				}
  				: function(update) { deferred.progress(update); };

  			handlers.push(function(promise) {
  				promise.then(onFulfilled, onRejected)
  					.then(deferred.resolve, deferred.reject, progressHandler);
  			});

  			progressHandlers.push(progressHandler);

  			return deferred.promise;
  		};

  		/**
  		 * Issue a progress event, notifying all progress listeners
  		 * @private
  		 * @param {*} update progress event payload to pass to all listeners
  		 */
  		_progress = function(update) {
  			processQueue(progressHandlers, update);
  			return update;
  		};

  		/**
  		 * Transition from pre-resolution state to post-resolution state, notifying
  		 * all listeners of the resolution or rejection
  		 * @private
  		 * @param {*} value the value of this deferred
  		 */
  		_resolve = function(value) {
  			value = resolve(value);

  			// Replace _then with one that directly notifies with the result.
  			_then = value.then;
  			// Replace _resolve so that this Deferred can only be resolved once
  			_resolve = resolve;
  			// Make _progress a noop, to disallow progress for the resolved promise.
  			_progress = noop;

  			// Notify handlers
  			processQueue(handlers, value);

  			// Free progressHandlers array since we'll never issue progress events
  			progressHandlers = handlers = undef;

  			return value;
  		};

  		return deferred;

  		/**
  		 * Wrapper to allow _then to be replaced safely
  		 * @param {function?} [onFulfilled] resolution handler
  		 * @param {function?} [onRejected] rejection handler
  		 * @param {function?} [onProgress] progress handler
  		 * @returns {Promise} new promise
  		 */
  		function then(onFulfilled, onRejected, onProgress) {
  			// TODO: Promises/A+ check typeof onFulfilled, onRejected, onProgress
  			return _then(onFulfilled, onRejected, onProgress);
  		}

  		/**
  		 * Wrapper to allow _resolve to be replaced
  		 */
  		function promiseResolve(val) {
  			return _resolve(val);
  		}

  		/**
  		 * Wrapper to allow _reject to be replaced
  		 */
  		function promiseReject(err) {
  			return _resolve(rejected(err));
  		}

  		/**
  		 * Wrapper to allow _progress to be replaced
  		 */
  		function promiseProgress(update) {
  			return _progress(update);
  		}
  	}

  	/**
  	 * Determines if promiseOrValue is a promise or not.  Uses the feature
  	 * test from http://wiki.commonjs.org/wiki/Promises/A to determine if
  	 * promiseOrValue is a promise.
  	 *
  	 * @param {*} promiseOrValue anything
  	 * @returns {boolean} true if promiseOrValue is a {@link Promise}
  	 */
  	function isPromise(promiseOrValue) {
  		return promiseOrValue && typeof promiseOrValue.then === 'function';
  	}

  	/**
  	 * Initiates a competitive race, returning a promise that will resolve when
  	 * howMany of the supplied promisesOrValues have resolved, or will reject when
  	 * it becomes impossible for howMany to resolve, for example, when
  	 * (promisesOrValues.length - howMany) + 1 input promises reject.
  	 *
  	 * @param {Array} promisesOrValues array of anything, may contain a mix
  	 *      of promises and values
  	 * @param howMany {number} number of promisesOrValues to resolve
  	 * @param {function?} [onFulfilled] resolution handler
  	 * @param {function?} [onRejected] rejection handler
  	 * @param {function?} [onProgress] progress handler
  	 * @returns {Promise} promise that will resolve to an array of howMany values that
  	 * resolved first, or will reject with an array of (promisesOrValues.length - howMany) + 1
  	 * rejection reasons.
  	 */
  	function some(promisesOrValues, howMany, onFulfilled, onRejected, onProgress) {

  		checkCallbacks(2, arguments);

  		return when(promisesOrValues, function(promisesOrValues) {

  			var toResolve, toReject, values, reasons, deferred, fulfillOne, rejectOne, progress, len, i;

  			len = promisesOrValues.length >>> 0;

  			toResolve = Math.max(0, Math.min(howMany, len));
  			values = [];

  			toReject = (len - toResolve) + 1;
  			reasons = [];

  			deferred = defer();

  			// No items in the input, resolve immediately
  			if (!toResolve) {
  				deferred.resolve(values);

  			} else {
  				progress = deferred.progress;

  				rejectOne = function(reason) {
  					reasons.push(reason);
  					if(!--toReject) {
  						fulfillOne = rejectOne = noop;
  						deferred.reject(reasons);
  					}
  				};

  				fulfillOne = function(val) {
  					// This orders the values based on promise resolution order
  					// Another strategy would be to use the original position of
  					// the corresponding promise.
  					values.push(val);

  					if (!--toResolve) {
  						fulfillOne = rejectOne = noop;
  						deferred.resolve(values);
  					}
  				};

  				for(i = 0; i < len; ++i) {
  					if(i in promisesOrValues) {
  						when(promisesOrValues[i], fulfiller, rejecter, progress);
  					}
  				}
  			}

  			return deferred.then(onFulfilled, onRejected, onProgress);

  			function rejecter(reason) {
  				rejectOne(reason);
  			}

  			function fulfiller(val) {
  				fulfillOne(val);
  			}

  		});
  	}

  	/**
  	 * Initiates a competitive race, returning a promise that will resolve when
  	 * any one of the supplied promisesOrValues has resolved or will reject when
  	 * *all* promisesOrValues have rejected.
  	 *
  	 * @param {Array|Promise} promisesOrValues array of anything, may contain a mix
  	 *      of {@link Promise}s and values
  	 * @param {function?} [onFulfilled] resolution handler
  	 * @param {function?} [onRejected] rejection handler
  	 * @param {function?} [onProgress] progress handler
  	 * @returns {Promise} promise that will resolve to the value that resolved first, or
  	 * will reject with an array of all rejected inputs.
  	 */
  	function any(promisesOrValues, onFulfilled, onRejected, onProgress) {

  		function unwrapSingleResult(val) {
  			return onFulfilled ? onFulfilled(val[0]) : val[0];
  		}

  		return some(promisesOrValues, 1, unwrapSingleResult, onRejected, onProgress);
  	}

  	/**
  	 * Return a promise that will resolve only once all the supplied promisesOrValues
  	 * have resolved. The resolution value of the returned promise will be an array
  	 * containing the resolution values of each of the promisesOrValues.
  	 * @memberOf when
  	 *
  	 * @param {Array|Promise} promisesOrValues array of anything, may contain a mix
  	 *      of {@link Promise}s and values
  	 * @param {function?} [onFulfilled] resolution handler
  	 * @param {function?} [onRejected] rejection handler
  	 * @param {function?} [onProgress] progress handler
  	 * @returns {Promise}
  	 */
  	function all(promisesOrValues, onFulfilled, onRejected, onProgress) {
  		checkCallbacks(1, arguments);
  		return map(promisesOrValues, identity).then(onFulfilled, onRejected, onProgress);
  	}

  	/**
  	 * Joins multiple promises into a single returned promise.
  	 * @returns {Promise} a promise that will fulfill when *all* the input promises
  	 * have fulfilled, or will reject when *any one* of the input promises rejects.
  	 */
  	function join(/* ...promises */) {
  		return map(arguments, identity);
  	}

  	/**
  	 * Traditional map function, similar to `Array.prototype.map()`, but allows
  	 * input to contain {@link Promise}s and/or values, and mapFunc may return
  	 * either a value or a {@link Promise}
  	 *
  	 * @param {Array|Promise} promise array of anything, may contain a mix
  	 *      of {@link Promise}s and values
  	 * @param {function} mapFunc mapping function mapFunc(value) which may return
  	 *      either a {@link Promise} or value
  	 * @returns {Promise} a {@link Promise} that will resolve to an array containing
  	 *      the mapped output values.
  	 */
  	function map(promise, mapFunc) {
  		return when(promise, function(array) {
  			var results, len, toResolve, resolve, i, d;

  			// Since we know the resulting length, we can preallocate the results
  			// array to avoid array expansions.
  			toResolve = len = array.length >>> 0;
  			results = [];
  			d = defer();

  			if(!toResolve) {
  				d.resolve(results);
  			} else {

  				resolve = function resolveOne(item, i) {
  					when(item, mapFunc).then(function(mapped) {
  						results[i] = mapped;

  						if(!--toResolve) {
  							d.resolve(results);
  						}
  					}, d.reject);
  				};

  				// Since mapFunc may be async, get all invocations of it into flight
  				for(i = 0; i < len; i++) {
  					if(i in array) {
  						resolve(array[i], i);
  					} else {
  						--toResolve;
  					}
  				}

  			}

  			return d.promise;

  		});
  	}

  	/**
  	 * Traditional reduce function, similar to `Array.prototype.reduce()`, but
  	 * input may contain promises and/or values, and reduceFunc
  	 * may return either a value or a promise, *and* initialValue may
  	 * be a promise for the starting value.
  	 *
  	 * @param {Array|Promise} promise array or promise for an array of anything,
  	 *      may contain a mix of promises and values.
  	 * @param {function} reduceFunc reduce function reduce(currentValue, nextValue, index, total),
  	 *      where total is the total number of items being reduced, and will be the same
  	 *      in each call to reduceFunc.
  	 * @returns {Promise} that will resolve to the final reduced value
  	 */
  	function reduce(promise, reduceFunc /*, initialValue */) {
  		var args = slice.call(arguments, 1);

  		return when(promise, function(array) {
  			var total;

  			total = array.length;

  			// Wrap the supplied reduceFunc with one that handles promises and then
  			// delegates to the supplied.
  			args[0] = function (current, val, i) {
  				return when(current, function (c) {
  					return when(val, function (value) {
  						return reduceFunc(c, value, i, total);
  					});
  				});
  			};

  			return reduceArray.apply(array, args);
  		});
  	}

  	/**
  	 * Ensure that resolution of promiseOrValue will trigger resolver with the
  	 * value or reason of promiseOrValue, or instead with resolveValue if it is provided.
  	 *
  	 * @param promiseOrValue
  	 * @param {Object} resolver
  	 * @param {function} resolver.resolve
  	 * @param {function} resolver.reject
  	 * @param {*} [resolveValue]
  	 * @returns {Promise}
  	 */
  	function chain(promiseOrValue, resolver, resolveValue) {
  		var useResolveValue = arguments.length > 2;

  		return when(promiseOrValue,
  			function(val) {
  				val = useResolveValue ? resolveValue : val;
  				resolver.resolve(val);
  				return val;
  			},
  			function(reason) {
  				resolver.reject(reason);
  				return rejected(reason);
  			},
  			resolver.progress
  		);
  	}

  	//
  	// Utility functions
  	//

  	/**
  	 * Apply all functions in queue to value
  	 * @param {Array} queue array of functions to execute
  	 * @param {*} value argument passed to each function
  	 */
  	function processQueue(queue, value) {
  		var handler, i = 0;

  		while (handler = queue[i++]) {
  			handler(value);
  		}
  	}

  	/**
  	 * Helper that checks arrayOfCallbacks to ensure that each element is either
  	 * a function, or null or undefined.
  	 * @private
  	 * @param {number} start index at which to start checking items in arrayOfCallbacks
  	 * @param {Array} arrayOfCallbacks array to check
  	 * @throws {Error} if any element of arrayOfCallbacks is something other than
  	 * a functions, null, or undefined.
  	 */
  	function checkCallbacks(start, arrayOfCallbacks) {
  		// TODO: Promises/A+ update type checking and docs
  		var arg, i = arrayOfCallbacks.length;

  		while(i > start) {
  			arg = arrayOfCallbacks[--i];

  			if (arg != null && typeof arg != 'function') {
  				throw new Error('arg '+i+' must be a function');
  			}
  		}
  	}

  	/**
  	 * No-Op function used in method replacement
  	 * @private
  	 */
  	function noop() {}

  	slice = [].slice;

  	// ES5 reduce implementation if native not available
  	// See: http://es5.github.com/#x15.4.4.21 as there are many
  	// specifics and edge cases.
  	reduceArray = [].reduce ||
  		function(reduceFunc /*, initialValue */) {
  			/*jshint maxcomplexity: 7*/

  			// ES5 dictates that reduce.length === 1

  			// This implementation deviates from ES5 spec in the following ways:
  			// 1. It does not check if reduceFunc is a Callable

  			var arr, args, reduced, len, i;

  			i = 0;
  			// This generates a jshint warning, despite being valid
  			// "Missing 'new' prefix when invoking a constructor."
  			// See https://github.com/jshint/jshint/issues/392
  			arr = Object(this);
  			len = arr.length >>> 0;
  			args = arguments;

  			// If no initialValue, use first item of array (we know length !== 0 here)
  			// and adjust i to start at second item
  			if(args.length <= 1) {
  				// Skip to the first real element in the array
  				for(;;) {
  					if(i in arr) {
  						reduced = arr[i++];
  						break;
  					}

  					// If we reached the end of the array without finding any real
  					// elements, it's a TypeError
  					if(++i >= len) {
  						throw new TypeError();
  					}
  				}
  			} else {
  				// If initialValue provided, use it
  				reduced = args[1];
  			}

  			// Do the actual reduce
  			for(;i < len; ++i) {
  				// Skip holes
  				if(i in arr) {
  					reduced = reduceFunc(reduced, arr[i], i, arr);
  				}
  			}

  			return reduced;
  		};

  	function identity(x) {
  		return x;
  	}

  /**
   * @private
   */
  function appendForwardSlash(url) {
    if (url.length === 0 || url[url.length - 1] !== "/") {
      url = url + "/";
    }
    return url;
  }

  /**
   * Clones an object, returning a new object containing the same properties.
   *
   * @function
   *
   * @param {Object} object The object to clone.
   * @param {Boolean} [deep=false] If true, all properties will be deep cloned recursively.
   * @returns {Object} The cloned object.
   */
  function clone(object, deep) {
    if (object === null || typeof object !== "object") {
      return object;
    }

    deep = defaultValue(deep, false);

    var result = new object.constructor();
    for (var propertyName in object) {
      if (object.hasOwnProperty(propertyName)) {
        var value = object[propertyName];
        if (deep) {
          value = clone(value, deep);
        }
        result[propertyName] = value;
      }
    }

    return result;
  }

  /**
   * Merges two objects, copying their properties onto a new combined object. When two objects have the same
   * property, the value of the property on the first object is used.  If either object is undefined,
   * it will be treated as an empty object.
   *
   * @example
   * var object1 = {
   *     propOne : 1,
   *     propTwo : {
   *         value1 : 10
   *     }
   * }
   * var object2 = {
   *     propTwo : 2
   * }
   * var final = Cesium.combine(object1, object2);
   *
   * // final === {
   * //     propOne : 1,
   * //     propTwo : {
   * //         value1 : 10
   * //     }
   * // }
   *
   * @param {Object} [object1] The first object to merge.
   * @param {Object} [object2] The second object to merge.
   * @param {Boolean} [deep=false] Perform a recursive merge.
   * @returns {Object} The combined object containing all properties from both objects.
   *
   * @function
   */
  function combine(object1, object2, deep) {
    deep = defaultValue(deep, false);

    var result = {};

    var object1Defined = defined(object1);
    var object2Defined = defined(object2);
    var property;
    var object1Value;
    var object2Value;
    if (object1Defined) {
      for (property in object1) {
        if (object1.hasOwnProperty(property)) {
          object1Value = object1[property];
          if (
            object2Defined &&
            deep &&
            typeof object1Value === "object" &&
            object2.hasOwnProperty(property)
          ) {
            object2Value = object2[property];
            if (typeof object2Value === "object") {
              result[property] = combine(object1Value, object2Value, deep);
            } else {
              result[property] = object1Value;
            }
          } else {
            result[property] = object1Value;
          }
        }
      }
    }
    if (object2Defined) {
      for (property in object2) {
        if (
          object2.hasOwnProperty(property) &&
          !result.hasOwnProperty(property)
        ) {
          object2Value = object2[property];
          result[property] = object2Value;
        }
      }
    }
    return result;
  }

  /**
   * Given a URI, returns the base path of the URI.
   * @function
   *
   * @param {String} uri The Uri.
   * @param {Boolean} [includeQuery = false] Whether or not to include the query string and fragment form the uri
   * @returns {String} The base path of the Uri.
   *
   * @example
   * // basePath will be "/Gallery/";
   * var basePath = Cesium.getBaseUri('/Gallery/simple.czml?value=true&example=false');
   *
   * // basePath will be "/Gallery/?value=true&example=false";
   * var basePath = Cesium.getBaseUri('/Gallery/simple.czml?value=true&example=false', true);
   */
  function getBaseUri(uri, includeQuery) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(uri)) {
      throw new DeveloperError("uri is required.");
    }
    //>>includeEnd('debug');

    var basePath = "";
    var i = uri.lastIndexOf("/");
    if (i !== -1) {
      basePath = uri.substring(0, i + 1);
    }

    if (!includeQuery) {
      return basePath;
    }

    uri = new URI(uri);
    if (defined(uri.query)) {
      basePath += "?" + uri.query;
    }
    if (defined(uri.fragment)) {
      basePath += "#" + uri.fragment;
    }

    return basePath;
  }

  /**
   * Given a URI, returns the extension of the URI.
   * @function getExtensionFromUri
   *
   * @param {String} uri The Uri.
   * @returns {String} The extension of the Uri.
   *
   * @example
   * //extension will be "czml";
   * var extension = Cesium.getExtensionFromUri('/Gallery/simple.czml?value=true&example=false');
   */
  function getExtensionFromUri(uri) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(uri)) {
      throw new DeveloperError("uri is required.");
    }
    //>>includeEnd('debug');

    var uriObject = new URI(uri);
    uriObject.normalize();
    var path = uriObject.path;
    var index = path.lastIndexOf("/");
    if (index !== -1) {
      path = path.substr(index + 1);
    }
    index = path.lastIndexOf(".");
    if (index === -1) {
      path = "";
    } else {
      path = path.substr(index + 1);
    }
    return path;
  }

  var blobUriRegex = /^blob:/i;

  /**
   * Determines if the specified uri is a blob uri.
   *
   * @function isBlobUri
   *
   * @param {String} uri The uri to test.
   * @returns {Boolean} true when the uri is a blob uri; otherwise, false.
   *
   * @private
   */
  function isBlobUri(uri) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("uri", uri);
    //>>includeEnd('debug');

    return blobUriRegex.test(uri);
  }

  var a;

  /**
   * Given a URL, determine whether that URL is considered cross-origin to the current page.
   *
   * @private
   */
  function isCrossOriginUrl(url) {
    if (!defined(a)) {
      a = document.createElement("a");
    }

    // copy window location into the anchor to get consistent results
    // when the port is default for the protocol (e.g. 80 for HTTP)
    a.href = window.location.href;

    // host includes both hostname and port if the port is not standard
    var host = a.host;
    var protocol = a.protocol;

    a.href = url;
    // IE only absolutizes href on get, not set
    // eslint-disable-next-line no-self-assign
    a.href = a.href;

    return protocol !== a.protocol || host !== a.host;
  }

  var dataUriRegex = /^data:/i;

  /**
   * Determines if the specified uri is a data uri.
   *
   * @function isDataUri
   *
   * @param {String} uri The uri to test.
   * @returns {Boolean} true when the uri is a data uri; otherwise, false.
   *
   * @private
   */
  function isDataUri(uri) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("uri", uri);
    //>>includeEnd('debug');

    return dataUriRegex.test(uri);
  }

  /**
   * @private
   */
  function loadAndExecuteScript(url) {
    var deferred = when.defer();
    var script = document.createElement("script");
    script.async = true;
    script.src = url;

    var head = document.getElementsByTagName("head")[0];
    script.onload = function () {
      script.onload = undefined;
      head.removeChild(script);
      deferred.resolve();
    };
    script.onerror = function (e) {
      deferred.reject(e);
    };

    head.appendChild(script);

    return deferred.promise;
  }

  /**
   * Converts an object representing a set of name/value pairs into a query string,
   * with names and values encoded properly for use in a URL.  Values that are arrays
   * will produce multiple values with the same name.
   * @function objectToQuery
   *
   * @param {Object} obj The object containing data to encode.
   * @returns {String} An encoded query string.
   *
   *
   * @example
   * var str = Cesium.objectToQuery({
   *     key1 : 'some value',
   *     key2 : 'a/b',
   *     key3 : ['x', 'y']
   * });
   *
   * @see queryToObject
   * // str will be:
   * // 'key1=some%20value&key2=a%2Fb&key3=x&key3=y'
   */
  function objectToQuery(obj) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(obj)) {
      throw new DeveloperError("obj is required.");
    }
    //>>includeEnd('debug');

    var result = "";
    for (var propName in obj) {
      if (obj.hasOwnProperty(propName)) {
        var value = obj[propName];

        var part = encodeURIComponent(propName) + "=";
        if (Array.isArray(value)) {
          for (var i = 0, len = value.length; i < len; ++i) {
            result += part + encodeURIComponent(value[i]) + "&";
          }
        } else {
          result += part + encodeURIComponent(value) + "&";
        }
      }
    }

    // trim last &
    result = result.slice(0, -1);

    // This function used to replace %20 with + which is more compact and readable.
    // However, some servers didn't properly handle + as a space.
    // https://github.com/CesiumGS/cesium/issues/2192

    return result;
  }

  /**
   * Parses a query string into an object, where the keys and values of the object are the
   * name/value pairs from the query string, decoded. If a name appears multiple times,
   * the value in the object will be an array of values.
   * @function queryToObject
   *
   * @param {String} queryString The query string.
   * @returns {Object} An object containing the parameters parsed from the query string.
   *
   *
   * @example
   * var obj = Cesium.queryToObject('key1=some%20value&key2=a%2Fb&key3=x&key3=y');
   * // obj will be:
   * // {
   * //   key1 : 'some value',
   * //   key2 : 'a/b',
   * //   key3 : ['x', 'y']
   * // }
   *
   * @see objectToQuery
   */
  function queryToObject(queryString) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(queryString)) {
      throw new DeveloperError("queryString is required.");
    }
    //>>includeEnd('debug');

    var result = {};
    if (queryString === "") {
      return result;
    }
    var parts = queryString.replace(/\+/g, "%20").split(/[&;]/);
    for (var i = 0, len = parts.length; i < len; ++i) {
      var subparts = parts[i].split("=");

      var name = decodeURIComponent(subparts[0]);
      var value = subparts[1];
      if (defined(value)) {
        value = decodeURIComponent(value);
      } else {
        value = "";
      }

      var resultValue = result[name];
      if (typeof resultValue === "string") {
        // expand the single value to an array
        result[name] = [resultValue, value];
      } else if (Array.isArray(resultValue)) {
        resultValue.push(value);
      } else {
        result[name] = value;
      }
    }
    return result;
  }

  /**
   * State of the request.
   *
   * @enum {Number}
   */
  var RequestState = {
    /**
     * Initial unissued state.
     *
     * @type Number
     * @constant
     */
    UNISSUED: 0,

    /**
     * Issued but not yet active. Will become active when open slots are available.
     *
     * @type Number
     * @constant
     */
    ISSUED: 1,

    /**
     * Actual http request has been sent.
     *
     * @type Number
     * @constant
     */
    ACTIVE: 2,

    /**
     * Request completed successfully.
     *
     * @type Number
     * @constant
     */
    RECEIVED: 3,

    /**
     * Request was cancelled, either explicitly or automatically because of low priority.
     *
     * @type Number
     * @constant
     */
    CANCELLED: 4,

    /**
     * Request failed.
     *
     * @type Number
     * @constant
     */
    FAILED: 5,
  };
  var RequestState$1 = Object.freeze(RequestState);

  /**
   * An enum identifying the type of request. Used for finer grained logging and priority sorting.
   *
   * @enum {Number}
   */
  var RequestType = {
    /**
     * Terrain request.
     *
     * @type Number
     * @constant
     */
    TERRAIN: 0,

    /**
     * Imagery request.
     *
     * @type Number
     * @constant
     */
    IMAGERY: 1,

    /**
     * 3D Tiles request.
     *
     * @type Number
     * @constant
     */
    TILES3D: 2,

    /**
     * Other request.
     *
     * @type Number
     * @constant
     */
    OTHER: 3,
  };
  var RequestType$1 = Object.freeze(RequestType);

  /**
   * Stores information for making a request. In general this does not need to be constructed directly.
   *
   * @alias Request
   * @constructor

   * @param {Object} [options] An object with the following properties:
   * @param {String} [options.url] The url to request.
   * @param {Request.RequestCallback} [options.requestFunction] The function that makes the actual data request.
   * @param {Request.CancelCallback} [options.cancelFunction] The function that is called when the request is cancelled.
   * @param {Request.PriorityCallback} [options.priorityFunction] The function that is called to update the request's priority, which occurs once per frame.
   * @param {Number} [options.priority=0.0] The initial priority of the request.
   * @param {Boolean} [options.throttle=false] Whether to throttle and prioritize the request. If false, the request will be sent immediately. If true, the request will be throttled and sent based on priority.
   * @param {Boolean} [options.throttleByServer=false] Whether to throttle the request by server.
   * @param {RequestType} [options.type=RequestType.OTHER] The type of request.
   */
  function Request(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var throttleByServer = defaultValue(options.throttleByServer, false);
    var throttle = defaultValue(options.throttle, false);

    /**
     * The URL to request.
     *
     * @type {String}
     */
    this.url = options.url;

    /**
     * The function that makes the actual data request.
     *
     * @type {Request.RequestCallback}
     */
    this.requestFunction = options.requestFunction;

    /**
     * The function that is called when the request is cancelled.
     *
     * @type {Request.CancelCallback}
     */
    this.cancelFunction = options.cancelFunction;

    /**
     * The function that is called to update the request's priority, which occurs once per frame.
     *
     * @type {Request.PriorityCallback}
     */
    this.priorityFunction = options.priorityFunction;

    /**
     * Priority is a unit-less value where lower values represent higher priority.
     * For world-based objects, this is usually the distance from the camera.
     * A request that does not have a priority function defaults to a priority of 0.
     *
     * If priorityFunction is defined, this value is updated every frame with the result of that call.
     *
     * @type {Number}
     * @default 0.0
     */
    this.priority = defaultValue(options.priority, 0.0);

    /**
     * Whether to throttle and prioritize the request. If false, the request will be sent immediately. If true, the
     * request will be throttled and sent based on priority.
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    this.throttle = throttle;

    /**
     * Whether to throttle the request by server. Browsers typically support about 6-8 parallel connections
     * for HTTP/1 servers, and an unlimited amount of connections for HTTP/2 servers. Setting this value
     * to <code>true</code> is preferable for requests going through HTTP/1 servers.
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    this.throttleByServer = throttleByServer;

    /**
     * Type of request.
     *
     * @type {RequestType}
     * @readonly
     *
     * @default RequestType.OTHER
     */
    this.type = defaultValue(options.type, RequestType$1.OTHER);

    /**
     * A key used to identify the server that a request is going to. It is derived from the url's authority and scheme.
     *
     * @type {String}
     *
     * @private
     */
    this.serverKey = undefined;

    /**
     * The current state of the request.
     *
     * @type {RequestState}
     * @readonly
     */
    this.state = RequestState$1.UNISSUED;

    /**
     * The requests's deferred promise.
     *
     * @type {Object}
     *
     * @private
     */
    this.deferred = undefined;

    /**
     * Whether the request was explicitly cancelled.
     *
     * @type {Boolean}
     *
     * @private
     */
    this.cancelled = false;
  }

  /**
   * Mark the request as cancelled.
   *
   * @private
   */
  Request.prototype.cancel = function () {
    this.cancelled = true;
  };

  /**
   * Duplicates a Request instance.
   *
   * @param {Request} [result] The object onto which to store the result.
   *
   * @returns {Request} The modified result parameter or a new Resource instance if one was not provided.
   */
  Request.prototype.clone = function (result) {
    if (!defined(result)) {
      return new Request(this);
    }

    result.url = this.url;
    result.requestFunction = this.requestFunction;
    result.cancelFunction = this.cancelFunction;
    result.priorityFunction = this.priorityFunction;
    result.priority = this.priority;
    result.throttle = this.throttle;
    result.throttleByServer = this.throttleByServer;
    result.type = this.type;
    result.serverKey = this.serverKey;

    // These get defaulted because the cloned request hasn't been issued
    result.state = this.RequestState.UNISSUED;
    result.deferred = undefined;
    result.cancelled = false;

    return result;
  };

  /**
   * Parses the result of XMLHttpRequest's getAllResponseHeaders() method into
   * a dictionary.
   *
   * @function parseResponseHeaders
   *
   * @param {String} headerString The header string returned by getAllResponseHeaders().  The format is
   *                 described here: http://www.w3.org/TR/XMLHttpRequest/#the-getallresponseheaders()-method
   * @returns {Object} A dictionary of key/value pairs, where each key is the name of a header and the corresponding value
   *                   is that header's value.
   *
   * @private
   */
  function parseResponseHeaders(headerString) {
    var headers = {};

    if (!headerString) {
      return headers;
    }

    var headerPairs = headerString.split("\u000d\u000a");

    for (var i = 0; i < headerPairs.length; ++i) {
      var headerPair = headerPairs[i];
      // Can't use split() here because it does the wrong thing
      // if the header value has the string ": " in it.
      var index = headerPair.indexOf("\u003a\u0020");
      if (index > 0) {
        var key = headerPair.substring(0, index);
        var val = headerPair.substring(index + 2);
        headers[key] = val;
      }
    }

    return headers;
  }

  /**
   * An event that is raised when a request encounters an error.
   *
   * @constructor
   * @alias RequestErrorEvent
   *
   * @param {Number} [statusCode] The HTTP error status code, such as 404.
   * @param {Object} [response] The response included along with the error.
   * @param {String|Object} [responseHeaders] The response headers, represented either as an object literal or as a
   *                        string in the format returned by XMLHttpRequest's getAllResponseHeaders() function.
   */
  function RequestErrorEvent(statusCode, response, responseHeaders) {
    /**
     * The HTTP error status code, such as 404.  If the error does not have a particular
     * HTTP code, this property will be undefined.
     *
     * @type {Number}
     */
    this.statusCode = statusCode;

    /**
     * The response included along with the error.  If the error does not include a response,
     * this property will be undefined.
     *
     * @type {Object}
     */
    this.response = response;

    /**
     * The headers included in the response, represented as an object literal of key/value pairs.
     * If the error does not include any headers, this property will be undefined.
     *
     * @type {Object}
     */
    this.responseHeaders = responseHeaders;

    if (typeof this.responseHeaders === "string") {
      this.responseHeaders = parseResponseHeaders(this.responseHeaders);
    }
  }

  /**
   * Creates a string representing this RequestErrorEvent.
   * @memberof RequestErrorEvent
   *
   * @returns {String} A string representing the provided RequestErrorEvent.
   */
  RequestErrorEvent.prototype.toString = function () {
    var str = "Request has failed.";
    if (defined(this.statusCode)) {
      str += " Status Code: " + this.statusCode;
    }
    return str;
  };

  /**
   * A generic utility class for managing subscribers for a particular event.
   * This class is usually instantiated inside of a container class and
   * exposed as a property for others to subscribe to.
   *
   * @alias Event
   * @constructor
   * @example
   * MyObject.prototype.myListener = function(arg1, arg2) {
   *     this.myArg1Copy = arg1;
   *     this.myArg2Copy = arg2;
   * }
   *
   * var myObjectInstance = new MyObject();
   * var evt = new Cesium.Event();
   * evt.addEventListener(MyObject.prototype.myListener, myObjectInstance);
   * evt.raiseEvent('1', '2');
   * evt.removeEventListener(MyObject.prototype.myListener);
   */
  function Event() {
    this._listeners = [];
    this._scopes = [];
    this._toRemove = [];
    this._insideRaiseEvent = false;
  }

  Object.defineProperties(Event.prototype, {
    /**
     * The number of listeners currently subscribed to the event.
     * @memberof Event.prototype
     * @type {Number}
     * @readonly
     */
    numberOfListeners: {
      get: function () {
        return this._listeners.length - this._toRemove.length;
      },
    },
  });

  /**
   * Registers a callback function to be executed whenever the event is raised.
   * An optional scope can be provided to serve as the <code>this</code> pointer
   * in which the function will execute.
   *
   * @param {Function} listener The function to be executed when the event is raised.
   * @param {Object} [scope] An optional object scope to serve as the <code>this</code>
   *        pointer in which the listener function will execute.
   * @returns {Event.RemoveCallback} A function that will remove this event listener when invoked.
   *
   * @see Event#raiseEvent
   * @see Event#removeEventListener
   */
  Event.prototype.addEventListener = function (listener, scope) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.func("listener", listener);
    //>>includeEnd('debug');

    this._listeners.push(listener);
    this._scopes.push(scope);

    var event = this;
    return function () {
      event.removeEventListener(listener, scope);
    };
  };

  /**
   * Unregisters a previously registered callback.
   *
   * @param {Function} listener The function to be unregistered.
   * @param {Object} [scope] The scope that was originally passed to addEventListener.
   * @returns {Boolean} <code>true</code> if the listener was removed; <code>false</code> if the listener and scope are not registered with the event.
   *
   * @see Event#addEventListener
   * @see Event#raiseEvent
   */
  Event.prototype.removeEventListener = function (listener, scope) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.func("listener", listener);
    //>>includeEnd('debug');

    var listeners = this._listeners;
    var scopes = this._scopes;

    var index = -1;
    for (var i = 0; i < listeners.length; i++) {
      if (listeners[i] === listener && scopes[i] === scope) {
        index = i;
        break;
      }
    }

    if (index !== -1) {
      if (this._insideRaiseEvent) {
        //In order to allow removing an event subscription from within
        //a callback, we don't actually remove the items here.  Instead
        //remember the index they are at and undefined their value.
        this._toRemove.push(index);
        listeners[index] = undefined;
        scopes[index] = undefined;
      } else {
        listeners.splice(index, 1);
        scopes.splice(index, 1);
      }
      return true;
    }

    return false;
  };

  function compareNumber(a, b) {
    return b - a;
  }

  /**
   * Raises the event by calling each registered listener with all supplied arguments.
   *
   * @param {...Object} arguments This method takes any number of parameters and passes them through to the listener functions.
   *
   * @see Event#addEventListener
   * @see Event#removeEventListener
   */
  Event.prototype.raiseEvent = function () {
    this._insideRaiseEvent = true;

    var i;
    var listeners = this._listeners;
    var scopes = this._scopes;
    var length = listeners.length;

    for (i = 0; i < length; i++) {
      var listener = listeners[i];
      if (defined(listener)) {
        listeners[i].apply(scopes[i], arguments);
      }
    }

    //Actually remove items removed in removeEventListener.
    var toRemove = this._toRemove;
    length = toRemove.length;
    if (length > 0) {
      toRemove.sort(compareNumber);
      for (i = 0; i < length; i++) {
        var index = toRemove[i];
        listeners.splice(index, 1);
        scopes.splice(index, 1);
      }
      toRemove.length = 0;
    }

    this._insideRaiseEvent = false;
  };

  /**
   * Array implementation of a heap.
   *
   * @alias Heap
   * @constructor
   * @private
   *
   * @param {Object} options Object with the following properties:
   * @param {Heap.ComparatorCallback} options.comparator The comparator to use for the heap. If comparator(a, b) is less than 0, sort a to a lower index than b, otherwise sort to a higher index.
   */
  function Heap(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.defined("options.comparator", options.comparator);
    //>>includeEnd('debug');

    this._comparator = options.comparator;
    this._array = [];
    this._length = 0;
    this._maximumLength = undefined;
  }

  Object.defineProperties(Heap.prototype, {
    /**
     * Gets the length of the heap.
     *
     * @memberof Heap.prototype
     *
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._length;
      },
    },

    /**
     * Gets the internal array.
     *
     * @memberof Heap.prototype
     *
     * @type {Array}
     * @readonly
     */
    internalArray: {
      get: function () {
        return this._array;
      },
    },

    /**
     * Gets and sets the maximum length of the heap.
     *
     * @memberof Heap.prototype
     *
     * @type {Number}
     */
    maximumLength: {
      get: function () {
        return this._maximumLength;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("maximumLength", value, 0);
        //>>includeEnd('debug');
        var originalLength = this._length;
        if (value < originalLength) {
          var array = this._array;
          // Remove trailing references
          for (var i = value; i < originalLength; ++i) {
            array[i] = undefined;
          }
          this._length = value;
          array.length = value;
        }
        this._maximumLength = value;
      },
    },

    /**
     * The comparator to use for the heap. If comparator(a, b) is less than 0, sort a to a lower index than b, otherwise sort to a higher index.
     *
     * @memberof Heap.prototype
     *
     * @type {Heap.ComparatorCallback}
     */
    comparator: {
      get: function () {
        return this._comparator;
      },
    },
  });

  function swap(array, a, b) {
    var temp = array[a];
    array[a] = array[b];
    array[b] = temp;
  }

  /**
   * Resizes the internal array of the heap.
   *
   * @param {Number} [length] The length to resize internal array to. Defaults to the current length of the heap.
   */
  Heap.prototype.reserve = function (length) {
    length = defaultValue(length, this._length);
    this._array.length = length;
  };

  /**
   * Update the heap so that index and all descendants satisfy the heap property.
   *
   * @param {Number} [index=0] The starting index to heapify from.
   */
  Heap.prototype.heapify = function (index) {
    index = defaultValue(index, 0);
    var length = this._length;
    var comparator = this._comparator;
    var array = this._array;
    var candidate = -1;
    var inserting = true;

    while (inserting) {
      var right = 2 * (index + 1);
      var left = right - 1;

      if (left < length && comparator(array[left], array[index]) < 0) {
        candidate = left;
      } else {
        candidate = index;
      }

      if (right < length && comparator(array[right], array[candidate]) < 0) {
        candidate = right;
      }
      if (candidate !== index) {
        swap(array, candidate, index);
        index = candidate;
      } else {
        inserting = false;
      }
    }
  };

  /**
   * Resort the heap.
   */
  Heap.prototype.resort = function () {
    var length = this._length;
    for (var i = Math.ceil(length / 2); i >= 0; --i) {
      this.heapify(i);
    }
  };

  /**
   * Insert an element into the heap. If the length would grow greater than maximumLength
   * of the heap, extra elements are removed.
   *
   * @param {*} element The element to insert
   *
   * @return {*} The element that was removed from the heap if the heap is at full capacity.
   */
  Heap.prototype.insert = function (element) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("element", element);
    //>>includeEnd('debug');

    var array = this._array;
    var comparator = this._comparator;
    var maximumLength = this._maximumLength;

    var index = this._length++;
    if (index < array.length) {
      array[index] = element;
    } else {
      array.push(element);
    }

    while (index !== 0) {
      var parent = Math.floor((index - 1) / 2);
      if (comparator(array[index], array[parent]) < 0) {
        swap(array, index, parent);
        index = parent;
      } else {
        break;
      }
    }

    var removedElement;

    if (defined(maximumLength) && this._length > maximumLength) {
      removedElement = array[maximumLength];
      this._length = maximumLength;
    }

    return removedElement;
  };

  /**
   * Remove the element specified by index from the heap and return it.
   *
   * @param {Number} [index=0] The index to remove.
   * @returns {*} The specified element of the heap.
   */
  Heap.prototype.pop = function (index) {
    index = defaultValue(index, 0);
    if (this._length === 0) {
      return undefined;
    }
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.lessThan("index", index, this._length);
    //>>includeEnd('debug');

    var array = this._array;
    var root = array[index];
    swap(array, index, --this._length);
    this.heapify(index);
    array[this._length] = undefined; // Remove trailing reference
    return root;
  };

  function sortRequests(a, b) {
    return a.priority - b.priority;
  }

  var statistics = {
    numberOfAttemptedRequests: 0,
    numberOfActiveRequests: 0,
    numberOfCancelledRequests: 0,
    numberOfCancelledActiveRequests: 0,
    numberOfFailedRequests: 0,
    numberOfActiveRequestsEver: 0,
    lastNumberOfActiveRequests: 0,
  };

  var priorityHeapLength = 20;
  var requestHeap = new Heap({
    comparator: sortRequests,
  });
  requestHeap.maximumLength = priorityHeapLength;
  requestHeap.reserve(priorityHeapLength);

  var activeRequests = [];
  var numberOfActiveRequestsByServer = {};

  var pageUri =
    typeof document !== "undefined" ? new URI(document.location.href) : new URI();

  var requestCompletedEvent = new Event();

  /**
   * The request scheduler is used to track and constrain the number of active requests in order to prioritize incoming requests. The ability
   * to retain control over the number of requests in CesiumJS is important because due to events such as changes in the camera position,
   * a lot of new requests may be generated and a lot of in-flight requests may become redundant. The request scheduler manually constrains the
   * number of requests so that newer requests wait in a shorter queue and don't have to compete for bandwidth with requests that have expired.
   *
   * @namespace RequestScheduler
   *
   */
  function RequestScheduler() {}

  /**
   * The maximum number of simultaneous active requests. Un-throttled requests do not observe this limit.
   * @type {Number}
   * @default 50
   */
  RequestScheduler.maximumRequests = 50;

  /**
   * The maximum number of simultaneous active requests per server. Un-throttled requests or servers specifically
   * listed in {@link requestsByServer} do not observe this limit.
   * @type {Number}
   * @default 6
   */
  RequestScheduler.maximumRequestsPerServer = 6;

  /**
   * A per server key list of overrides to use for throttling instead of <code>maximumRequestsPerServer</code>
   * @type {Object}
   *
   * @example
   * RequestScheduler.requestsByServer = {
   *   'api.cesium.com:443': 18,
   *   'assets.cesium.com:443': 18
   * };
   */
  RequestScheduler.requestsByServer = {
    "api.cesium.com:443": 18,
    "assets.cesium.com:443": 18,
  };

  /**
   * Specifies if the request scheduler should throttle incoming requests, or let the browser queue requests under its control.
   * @type {Boolean}
   * @default true
   */
  RequestScheduler.throttleRequests = true;

  /**
   * When true, log statistics to the console every frame
   * @type {Boolean}
   * @default false
   * @private
   */
  RequestScheduler.debugShowStatistics = false;

  /**
   * An event that's raised when a request is completed.  Event handlers are passed
   * the error object if the request fails.
   *
   * @type {Event}
   * @default Event()
   * @private
   */
  RequestScheduler.requestCompletedEvent = requestCompletedEvent;

  Object.defineProperties(RequestScheduler, {
    /**
     * Returns the statistics used by the request scheduler.
     *
     * @memberof RequestScheduler
     *
     * @type Object
     * @readonly
     * @private
     */
    statistics: {
      get: function () {
        return statistics;
      },
    },

    /**
     * The maximum size of the priority heap. This limits the number of requests that are sorted by priority. Only applies to requests that are not yet active.
     *
     * @memberof RequestScheduler
     *
     * @type {Number}
     * @default 20
     * @private
     */
    priorityHeapLength: {
      get: function () {
        return priorityHeapLength;
      },
      set: function (value) {
        // If the new length shrinks the heap, need to cancel some of the requests.
        // Since this value is not intended to be tweaked regularly it is fine to just cancel the high priority requests.
        if (value < priorityHeapLength) {
          while (requestHeap.length > value) {
            var request = requestHeap.pop();
            cancelRequest(request);
          }
        }
        priorityHeapLength = value;
        requestHeap.maximumLength = value;
        requestHeap.reserve(value);
      },
    },
  });

  function updatePriority(request) {
    if (defined(request.priorityFunction)) {
      request.priority = request.priorityFunction();
    }
  }

  function serverHasOpenSlots(serverKey) {
    var maxRequests = defaultValue(
      RequestScheduler.requestsByServer[serverKey],
      RequestScheduler.maximumRequestsPerServer
    );
    return numberOfActiveRequestsByServer[serverKey] < maxRequests;
  }

  function issueRequest(request) {
    if (request.state === RequestState$1.UNISSUED) {
      request.state = RequestState$1.ISSUED;
      request.deferred = when.defer();
    }
    return request.deferred.promise;
  }

  function getRequestReceivedFunction(request) {
    return function (results) {
      if (request.state === RequestState$1.CANCELLED) {
        // If the data request comes back but the request is cancelled, ignore it.
        return;
      }
      --statistics.numberOfActiveRequests;
      --numberOfActiveRequestsByServer[request.serverKey];
      requestCompletedEvent.raiseEvent();
      request.state = RequestState$1.RECEIVED;
      request.deferred.resolve(results);
      // explicitly set to undefined to ensure GC of request response data. See #8843
      request.deferred = undefined;
    };
  }

  function getRequestFailedFunction(request) {
    return function (error) {
      if (request.state === RequestState$1.CANCELLED) {
        // If the data request comes back but the request is cancelled, ignore it.
        return;
      }
      ++statistics.numberOfFailedRequests;
      --statistics.numberOfActiveRequests;
      --numberOfActiveRequestsByServer[request.serverKey];
      requestCompletedEvent.raiseEvent(error);
      request.state = RequestState$1.FAILED;
      request.deferred.reject(error);
    };
  }

  function startRequest(request) {
    var promise = issueRequest(request);
    request.state = RequestState$1.ACTIVE;
    activeRequests.push(request);
    ++statistics.numberOfActiveRequests;
    ++statistics.numberOfActiveRequestsEver;
    ++numberOfActiveRequestsByServer[request.serverKey];
    request
      .requestFunction()
      .then(getRequestReceivedFunction(request))
      .otherwise(getRequestFailedFunction(request));
    return promise;
  }

  function cancelRequest(request) {
    var active = request.state === RequestState$1.ACTIVE;
    request.state = RequestState$1.CANCELLED;
    ++statistics.numberOfCancelledRequests;
    // check that deferred has not been cleared since cancelRequest can be called
    // on a finished request, e.g. by clearForSpecs during tests
    if (defined(request.deferred)) {
      request.deferred.reject();
      request.deferred = undefined;
    }

    if (active) {
      --statistics.numberOfActiveRequests;
      --numberOfActiveRequestsByServer[request.serverKey];
      ++statistics.numberOfCancelledActiveRequests;
    }

    if (defined(request.cancelFunction)) {
      request.cancelFunction();
    }
  }

  /**
   * Sort requests by priority and start requests.
   * @private
   */
  RequestScheduler.update = function () {
    var i;
    var request;

    // Loop over all active requests. Cancelled, failed, or received requests are removed from the array to make room for new requests.
    var removeCount = 0;
    var activeLength = activeRequests.length;
    for (i = 0; i < activeLength; ++i) {
      request = activeRequests[i];
      if (request.cancelled) {
        // Request was explicitly cancelled
        cancelRequest(request);
      }
      if (request.state !== RequestState$1.ACTIVE) {
        // Request is no longer active, remove from array
        ++removeCount;
        continue;
      }
      if (removeCount > 0) {
        // Shift back to fill in vacated slots from completed requests
        activeRequests[i - removeCount] = request;
      }
    }
    activeRequests.length -= removeCount;

    // Update priority of issued requests and resort the heap
    var issuedRequests = requestHeap.internalArray;
    var issuedLength = requestHeap.length;
    for (i = 0; i < issuedLength; ++i) {
      updatePriority(issuedRequests[i]);
    }
    requestHeap.resort();

    // Get the number of open slots and fill with the highest priority requests.
    // Un-throttled requests are automatically added to activeRequests, so activeRequests.length may exceed maximumRequests
    var openSlots = Math.max(
      RequestScheduler.maximumRequests - activeRequests.length,
      0
    );
    var filledSlots = 0;
    while (filledSlots < openSlots && requestHeap.length > 0) {
      // Loop until all open slots are filled or the heap becomes empty
      request = requestHeap.pop();
      if (request.cancelled) {
        // Request was explicitly cancelled
        cancelRequest(request);
        continue;
      }

      if (request.throttleByServer && !serverHasOpenSlots(request.serverKey)) {
        // Open slots are available, but the request is throttled by its server. Cancel and try again later.
        cancelRequest(request);
        continue;
      }

      startRequest(request);
      ++filledSlots;
    }

    updateStatistics();
  };

  /**
   * Get the server key from a given url.
   *
   * @param {String} url The url.
   * @returns {String} The server key.
   * @private
   */
  RequestScheduler.getServerKey = function (url) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("url", url);
    //>>includeEnd('debug');

    var uri = new URI(url).resolve(pageUri);
    uri.normalize();
    var serverKey = uri.authority;
    if (!/:/.test(serverKey)) {
      // If the authority does not contain a port number, add port 443 for https or port 80 for http
      serverKey = serverKey + ":" + (uri.scheme === "https" ? "443" : "80");
    }

    var length = numberOfActiveRequestsByServer[serverKey];
    if (!defined(length)) {
      numberOfActiveRequestsByServer[serverKey] = 0;
    }

    return serverKey;
  };

  /**
   * Issue a request. If request.throttle is false, the request is sent immediately. Otherwise the request will be
   * queued and sorted by priority before being sent.
   *
   * @param {Request} request The request object.
   *
   * @returns {Promise|undefined} A Promise for the requested data, or undefined if this request does not have high enough priority to be issued.
   *
   * @private
   */
  RequestScheduler.request = function (request) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("request", request);
    Check.typeOf.string("request.url", request.url);
    Check.typeOf.func("request.requestFunction", request.requestFunction);
    //>>includeEnd('debug');

    if (isDataUri(request.url) || isBlobUri(request.url)) {
      requestCompletedEvent.raiseEvent();
      request.state = RequestState$1.RECEIVED;
      return request.requestFunction();
    }

    ++statistics.numberOfAttemptedRequests;

    if (!defined(request.serverKey)) {
      request.serverKey = RequestScheduler.getServerKey(request.url);
    }

    if (
      RequestScheduler.throttleRequests &&
      request.throttleByServer &&
      !serverHasOpenSlots(request.serverKey)
    ) {
      // Server is saturated. Try again later.
      return undefined;
    }

    if (!RequestScheduler.throttleRequests || !request.throttle) {
      return startRequest(request);
    }

    if (activeRequests.length >= RequestScheduler.maximumRequests) {
      // Active requests are saturated. Try again later.
      return undefined;
    }

    // Insert into the priority heap and see if a request was bumped off. If this request is the lowest
    // priority it will be returned.
    updatePriority(request);
    var removedRequest = requestHeap.insert(request);

    if (defined(removedRequest)) {
      if (removedRequest === request) {
        // Request does not have high enough priority to be issued
        return undefined;
      }
      // A previously issued request has been bumped off the priority heap, so cancel it
      cancelRequest(removedRequest);
    }

    return issueRequest(request);
  };

  function updateStatistics() {
    if (!RequestScheduler.debugShowStatistics) {
      return;
    }

    if (
      statistics.numberOfActiveRequests === 0 &&
      statistics.lastNumberOfActiveRequests > 0
    ) {
      if (statistics.numberOfAttemptedRequests > 0) {
        console.log(
          "Number of attempted requests: " + statistics.numberOfAttemptedRequests
        );
        statistics.numberOfAttemptedRequests = 0;
      }

      if (statistics.numberOfCancelledRequests > 0) {
        console.log(
          "Number of cancelled requests: " + statistics.numberOfCancelledRequests
        );
        statistics.numberOfCancelledRequests = 0;
      }

      if (statistics.numberOfCancelledActiveRequests > 0) {
        console.log(
          "Number of cancelled active requests: " +
            statistics.numberOfCancelledActiveRequests
        );
        statistics.numberOfCancelledActiveRequests = 0;
      }

      if (statistics.numberOfFailedRequests > 0) {
        console.log(
          "Number of failed requests: " + statistics.numberOfFailedRequests
        );
        statistics.numberOfFailedRequests = 0;
      }
    }

    statistics.lastNumberOfActiveRequests = statistics.numberOfActiveRequests;
  }

  /**
   * For testing only. Clears any requests that may not have completed from previous tests.
   *
   * @private
   */
  RequestScheduler.clearForSpecs = function () {
    while (requestHeap.length > 0) {
      var request = requestHeap.pop();
      cancelRequest(request);
    }
    var length = activeRequests.length;
    for (var i = 0; i < length; ++i) {
      cancelRequest(activeRequests[i]);
    }
    activeRequests.length = 0;
    numberOfActiveRequestsByServer = {};

    // Clear stats
    statistics.numberOfAttemptedRequests = 0;
    statistics.numberOfActiveRequests = 0;
    statistics.numberOfCancelledRequests = 0;
    statistics.numberOfCancelledActiveRequests = 0;
    statistics.numberOfFailedRequests = 0;
    statistics.numberOfActiveRequestsEver = 0;
    statistics.lastNumberOfActiveRequests = 0;
  };

  /**
   * For testing only.
   *
   * @private
   */
  RequestScheduler.numberOfActiveRequestsByServer = function (serverKey) {
    return numberOfActiveRequestsByServer[serverKey];
  };

  /**
   * For testing only.
   *
   * @private
   */
  RequestScheduler.requestHeap = requestHeap;

  /**
   * A singleton that contains all of the servers that are trusted. Credentials will be sent with
   * any requests to these servers.
   *
   * @namespace TrustedServers
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  var TrustedServers = {};
  var _servers = {};

  /**
   * Adds a trusted server to the registry
   *
   * @param {String} host The host to be added.
   * @param {Number} port The port used to access the host.
   *
   * @example
   * // Add a trusted server
   * TrustedServers.add('my.server.com', 80);
   */
  TrustedServers.add = function (host, port) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(host)) {
      throw new DeveloperError("host is required.");
    }
    if (!defined(port) || port <= 0) {
      throw new DeveloperError("port is required to be greater than 0.");
    }
    //>>includeEnd('debug');

    var authority = host.toLowerCase() + ":" + port;
    if (!defined(_servers[authority])) {
      _servers[authority] = true;
    }
  };

  /**
   * Removes a trusted server from the registry
   *
   * @param {String} host The host to be removed.
   * @param {Number} port The port used to access the host.
   *
   * @example
   * // Remove a trusted server
   * TrustedServers.remove('my.server.com', 80);
   */
  TrustedServers.remove = function (host, port) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(host)) {
      throw new DeveloperError("host is required.");
    }
    if (!defined(port) || port <= 0) {
      throw new DeveloperError("port is required to be greater than 0.");
    }
    //>>includeEnd('debug');

    var authority = host.toLowerCase() + ":" + port;
    if (defined(_servers[authority])) {
      delete _servers[authority];
    }
  };

  function getAuthority(url) {
    var uri = new URI(url);
    uri.normalize();

    // Removes username:password@ so we just have host[:port]
    var authority = uri.getAuthority();
    if (!defined(authority)) {
      return undefined; // Relative URL
    }

    if (authority.indexOf("@") !== -1) {
      var parts = authority.split("@");
      authority = parts[1];
    }

    // If the port is missing add one based on the scheme
    if (authority.indexOf(":") === -1) {
      var scheme = uri.getScheme();
      if (!defined(scheme)) {
        scheme = window.location.protocol;
        scheme = scheme.substring(0, scheme.length - 1);
      }
      if (scheme === "http") {
        authority += ":80";
      } else if (scheme === "https") {
        authority += ":443";
      } else {
        return undefined;
      }
    }

    return authority;
  }

  /**
   * Tests whether a server is trusted or not. The server must have been added with the port if it is included in the url.
   *
   * @param {String} url The url to be tested against the trusted list
   *
   * @returns {boolean} Returns true if url is trusted, false otherwise.
   *
   * @example
   * // Add server
   * TrustedServers.add('my.server.com', 81);
   *
   * // Check if server is trusted
   * if (TrustedServers.contains('https://my.server.com:81/path/to/file.png')) {
   *     // my.server.com:81 is trusted
   * }
   * if (TrustedServers.contains('https://my.server.com/path/to/file.png')) {
   *     // my.server.com isn't trusted
   * }
   */
  TrustedServers.contains = function (url) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(url)) {
      throw new DeveloperError("url is required.");
    }
    //>>includeEnd('debug');
    var authority = getAuthority(url);
    if (defined(authority) && defined(_servers[authority])) {
      return true;
    }

    return false;
  };

  /**
   * Clears the registry
   *
   * @example
   * // Remove a trusted server
   * TrustedServers.clear();
   */
  TrustedServers.clear = function () {
    _servers = {};
  };

  var xhrBlobSupported = (function () {
    try {
      var xhr = new XMLHttpRequest();
      xhr.open("GET", "#", true);
      xhr.responseType = "blob";
      return xhr.responseType === "blob";
    } catch (e) {
      return false;
    }
  })();

  /**
   * Parses a query string and returns the object equivalent.
   *
   * @param {Uri} uri The Uri with a query object.
   * @param {Resource} resource The Resource that will be assigned queryParameters.
   * @param {Boolean} merge If true, we'll merge with the resource's existing queryParameters. Otherwise they will be replaced.
   * @param {Boolean} preserveQueryParameters If true duplicate parameters will be concatenated into an array. If false, keys in uri will take precedence.
   *
   * @private
   */
  function parseQuery(uri, resource, merge, preserveQueryParameters) {
    var queryString = uri.query;
    if (!defined(queryString) || queryString.length === 0) {
      return {};
    }

    var query;
    // Special case we run into where the querystring is just a string, not key/value pairs
    if (queryString.indexOf("=") === -1) {
      var result = {};
      result[queryString] = undefined;
      query = result;
    } else {
      query = queryToObject(queryString);
    }

    if (merge) {
      resource._queryParameters = combineQueryParameters(
        query,
        resource._queryParameters,
        preserveQueryParameters
      );
    } else {
      resource._queryParameters = query;
    }
    uri.query = undefined;
  }

  /**
   * Converts a query object into a string.
   *
   * @param {Uri} uri The Uri object that will have the query object set.
   * @param {Resource} resource The resource that has queryParameters
   *
   * @private
   */
  function stringifyQuery(uri, resource) {
    var queryObject = resource._queryParameters;

    var keys = Object.keys(queryObject);

    // We have 1 key with an undefined value, so this is just a string, not key/value pairs
    if (keys.length === 1 && !defined(queryObject[keys[0]])) {
      uri.query = keys[0];
    } else {
      uri.query = objectToQuery(queryObject);
    }
  }

  /**
   * Clones a value if it is defined, otherwise returns the default value
   *
   * @param {*} [val] The value to clone.
   * @param {*} [defaultVal] The default value.
   *
   * @returns {*} A clone of val or the defaultVal.
   *
   * @private
   */
  function defaultClone(val, defaultVal) {
    if (!defined(val)) {
      return defaultVal;
    }

    return defined(val.clone) ? val.clone() : clone(val);
  }

  /**
   * Checks to make sure the Resource isn't already being requested.
   *
   * @param {Request} request The request to check.
   *
   * @private
   */
  function checkAndResetRequest(request) {
    if (
      request.state === RequestState$1.ISSUED ||
      request.state === RequestState$1.ACTIVE
    ) {
      throw new RuntimeError("The Resource is already being fetched.");
    }

    request.state = RequestState$1.UNISSUED;
    request.deferred = undefined;
  }

  /**
   * This combines a map of query parameters.
   *
   * @param {Object} q1 The first map of query parameters. Values in this map will take precedence if preserveQueryParameters is false.
   * @param {Object} q2 The second map of query parameters.
   * @param {Boolean} preserveQueryParameters If true duplicate parameters will be concatenated into an array. If false, keys in q1 will take precedence.
   *
   * @returns {Object} The combined map of query parameters.
   *
   * @example
   * var q1 = {
   *   a: 1,
   *   b: 2
   * };
   * var q2 = {
   *   a: 3,
   *   c: 4
   * };
   * var q3 = {
   *   b: [5, 6],
   *   d: 7
   * }
   *
   * // Returns
   * // {
   * //   a: [1, 3],
   * //   b: 2,
   * //   c: 4
   * // };
   * combineQueryParameters(q1, q2, true);
   *
   * // Returns
   * // {
   * //   a: 1,
   * //   b: 2,
   * //   c: 4
   * // };
   * combineQueryParameters(q1, q2, false);
   *
   * // Returns
   * // {
   * //   a: 1,
   * //   b: [2, 5, 6],
   * //   d: 7
   * // };
   * combineQueryParameters(q1, q3, true);
   *
   * // Returns
   * // {
   * //   a: 1,
   * //   b: 2,
   * //   d: 7
   * // };
   * combineQueryParameters(q1, q3, false);
   *
   * @private
   */
  function combineQueryParameters(q1, q2, preserveQueryParameters) {
    if (!preserveQueryParameters) {
      return combine(q1, q2);
    }

    var result = clone(q1, true);
    for (var param in q2) {
      if (q2.hasOwnProperty(param)) {
        var value = result[param];
        var q2Value = q2[param];
        if (defined(value)) {
          if (!Array.isArray(value)) {
            value = result[param] = [value];
          }

          result[param] = value.concat(q2Value);
        } else {
          result[param] = Array.isArray(q2Value) ? q2Value.slice() : q2Value;
        }
      }
    }

    return result;
  }

  /**
   * A resource that includes the location and any other parameters we need to retrieve it or create derived resources. It also provides the ability to retry requests.
   *
   * @alias Resource
   * @constructor
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   *
   * @example
   * function refreshTokenRetryCallback(resource, error) {
   *   if (error.statusCode === 403) {
   *     // 403 status code means a new token should be generated
   *     return getNewAccessToken()
   *       .then(function(token) {
   *         resource.queryParameters.access_token = token;
   *         return true;
   *       })
   *       .otherwise(function() {
   *         return false;
   *       });
   *   }
   *
   *   return false;
   * }
   *
   * var resource = new Resource({
   *    url: 'http://server.com/path/to/resource.json',
   *    proxy: new DefaultProxy('/proxy/'),
   *    headers: {
   *      'X-My-Header': 'valueOfHeader'
   *    },
   *    queryParameters: {
   *      'access_token': '123-435-456-000'
   *    },
   *    retryCallback: refreshTokenRetryCallback,
   *    retryAttempts: 1
   * });
   */
  function Resource(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    if (typeof options === "string") {
      options = {
        url: options,
      };
    }

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("options.url", options.url);
    //>>includeEnd('debug');

    this._url = undefined;
    this._templateValues = defaultClone(options.templateValues, {});
    this._queryParameters = defaultClone(options.queryParameters, {});

    /**
     * Additional HTTP headers that will be sent with the request.
     *
     * @type {Object}
     */
    this.headers = defaultClone(options.headers, {});

    /**
     * A Request object that will be used. Intended for internal use only.
     *
     * @type {Request}
     */
    this.request = defaultValue(options.request, new Request());

    /**
     * A proxy to be used when loading the resource.
     *
     * @type {Proxy}
     */
    this.proxy = options.proxy;

    /**
     * Function to call when a request for this resource fails. If it returns true or a Promise that resolves to true, the request will be retried.
     *
     * @type {Function}
     */
    this.retryCallback = options.retryCallback;

    /**
     * The number of times the retryCallback should be called before giving up.
     *
     * @type {Number}
     */
    this.retryAttempts = defaultValue(options.retryAttempts, 0);
    this._retryCount = 0;

    var uri = new URI(options.url);
    parseQuery(uri, this, true, true);

    // Remove the fragment as it's not sent with a request
    uri.fragment = undefined;

    this._url = uri.toString();
  }

  /**
   * A helper function to create a resource depending on whether we have a String or a Resource
   *
   * @param {Resource|String} resource A Resource or a String to use when creating a new Resource.
   *
   * @returns {Resource} If resource is a String, a Resource constructed with the url and options. Otherwise the resource parameter is returned.
   *
   * @private
   */
  Resource.createIfNeeded = function (resource) {
    if (resource instanceof Resource) {
      // Keep existing request object. This function is used internally to duplicate a Resource, so that it can't
      //  be modified outside of a class that holds it (eg. an imagery or terrain provider). Since the Request objects
      //  are managed outside of the providers, by the tile loading code, we want to keep the request property the same so if it is changed
      //  in the underlying tiling code the requests for this resource will use it.
      return resource.getDerivedResource({
        request: resource.request,
      });
    }

    if (typeof resource !== "string") {
      return resource;
    }

    return new Resource({
      url: resource,
    });
  };

  var supportsImageBitmapOptionsPromise;
  /**
   * A helper function to check whether createImageBitmap supports passing ImageBitmapOptions.
   *
   * @returns {Promise<Boolean>} A promise that resolves to true if this browser supports creating an ImageBitmap with options.
   *
   * @private
   */
  Resource.supportsImageBitmapOptions = function () {
    // Until the HTML folks figure out what to do about this, we need to actually try loading an image to
    // know if this browser supports passing options to the createImageBitmap function.
    // https://github.com/whatwg/html/pull/4248
    if (defined(supportsImageBitmapOptionsPromise)) {
      return supportsImageBitmapOptionsPromise;
    }

    if (typeof createImageBitmap !== "function") {
      supportsImageBitmapOptionsPromise = when.resolve(false);
      return supportsImageBitmapOptionsPromise;
    }

    var imageDataUri =
      "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQImWP4////fwAJ+wP9CNHoHgAAAABJRU5ErkJggg==";

    supportsImageBitmapOptionsPromise = Resource.fetchBlob({
      url: imageDataUri,
    })
      .then(function (blob) {
        return createImageBitmap(blob, {
          imageOrientation: "flipY",
          premultiplyAlpha: "none",
        });
      })
      .then(function (imageBitmap) {
        return true;
      })
      .otherwise(function () {
        return false;
      });

    return supportsImageBitmapOptionsPromise;
  };

  Object.defineProperties(Resource, {
    /**
     * Returns true if blobs are supported.
     *
     * @memberof Resource
     * @type {Boolean}
     *
     * @readonly
     */
    isBlobSupported: {
      get: function () {
        return xhrBlobSupported;
      },
    },
  });

  Object.defineProperties(Resource.prototype, {
    /**
     * Query parameters appended to the url.
     *
     * @memberof Resource.prototype
     * @type {Object}
     *
     * @readonly
     */
    queryParameters: {
      get: function () {
        return this._queryParameters;
      },
    },

    /**
     * The key/value pairs used to replace template parameters in the url.
     *
     * @memberof Resource.prototype
     * @type {Object}
     *
     * @readonly
     */
    templateValues: {
      get: function () {
        return this._templateValues;
      },
    },

    /**
     * The url to the resource with template values replaced, query string appended and encoded by proxy if one was set.
     *
     * @memberof Resource.prototype
     * @type {String}
     */
    url: {
      get: function () {
        return this.getUrlComponent(true, true);
      },
      set: function (value) {
        var uri = new URI(value);

        parseQuery(uri, this, false);

        // Remove the fragment as it's not sent with a request
        uri.fragment = undefined;

        this._url = uri.toString();
      },
    },

    /**
     * The file extension of the resource.
     *
     * @memberof Resource.prototype
     * @type {String}
     *
     * @readonly
     */
    extension: {
      get: function () {
        return getExtensionFromUri(this._url);
      },
    },

    /**
     * True if the Resource refers to a data URI.
     *
     * @memberof Resource.prototype
     * @type {Boolean}
     */
    isDataUri: {
      get: function () {
        return isDataUri(this._url);
      },
    },

    /**
     * True if the Resource refers to a blob URI.
     *
     * @memberof Resource.prototype
     * @type {Boolean}
     */
    isBlobUri: {
      get: function () {
        return isBlobUri(this._url);
      },
    },

    /**
     * True if the Resource refers to a cross origin URL.
     *
     * @memberof Resource.prototype
     * @type {Boolean}
     */
    isCrossOriginUrl: {
      get: function () {
        return isCrossOriginUrl(this._url);
      },
    },

    /**
     * True if the Resource has request headers. This is equivalent to checking if the headers property has any keys.
     *
     * @memberof Resource.prototype
     * @type {Boolean}
     */
    hasHeaders: {
      get: function () {
        return Object.keys(this.headers).length > 0;
      },
    },
  });

  /**
   * Override Object#toString so that implicit string conversion gives the
   * complete URL represented by this Resource.
   *
   * @returns {String} The URL represented by this Resource
   */
  Resource.prototype.toString = function () {
    return this.getUrlComponent(true, true);
  };

  /**
   * Returns the url, optional with the query string and processed by a proxy.
   *
   * @param {Boolean} [query=false] If true, the query string is included.
   * @param {Boolean} [proxy=false] If true, the url is processed by the proxy object, if defined.
   *
   * @returns {String} The url with all the requested components.
   */
  Resource.prototype.getUrlComponent = function (query, proxy) {
    if (this.isDataUri) {
      return this._url;
    }

    var uri = new URI(this._url);

    if (query) {
      stringifyQuery(uri, this);
    }

    // objectToQuery escapes the placeholders.  Undo that.
    var url = uri.toString().replace(/%7B/g, "{").replace(/%7D/g, "}");

    var templateValues = this._templateValues;
    url = url.replace(/{(.*?)}/g, function (match, key) {
      var replacement = templateValues[key];
      if (defined(replacement)) {
        // use the replacement value from templateValues if there is one...
        return encodeURIComponent(replacement);
      }
      // otherwise leave it unchanged
      return match;
    });

    if (proxy && defined(this.proxy)) {
      url = this.proxy.getURL(url);
    }
    return url;
  };

  /**
   * Combines the specified object and the existing query parameters. This allows you to add many parameters at once,
   *  as opposed to adding them one at a time to the queryParameters property. If a value is already set, it will be replaced with the new value.
   *
   * @param {Object} params The query parameters
   * @param {Boolean} [useAsDefault=false] If true the params will be used as the default values, so they will only be set if they are undefined.
   */
  Resource.prototype.setQueryParameters = function (params, useAsDefault) {
    if (useAsDefault) {
      this._queryParameters = combineQueryParameters(
        this._queryParameters,
        params,
        false
      );
    } else {
      this._queryParameters = combineQueryParameters(
        params,
        this._queryParameters,
        false
      );
    }
  };

  /**
   * Combines the specified object and the existing query parameters. This allows you to add many parameters at once,
   *  as opposed to adding them one at a time to the queryParameters property.
   *
   * @param {Object} params The query parameters
   */
  Resource.prototype.appendQueryParameters = function (params) {
    this._queryParameters = combineQueryParameters(
      params,
      this._queryParameters,
      true
    );
  };

  /**
   * Combines the specified object and the existing template values. This allows you to add many values at once,
   *  as opposed to adding them one at a time to the templateValues property. If a value is already set, it will become an array and the new value will be appended.
   *
   * @param {Object} template The template values
   * @param {Boolean} [useAsDefault=false] If true the values will be used as the default values, so they will only be set if they are undefined.
   */
  Resource.prototype.setTemplateValues = function (template, useAsDefault) {
    if (useAsDefault) {
      this._templateValues = combine(this._templateValues, template);
    } else {
      this._templateValues = combine(template, this._templateValues);
    }
  };

  /**
   * Returns a resource relative to the current instance. All properties remain the same as the current instance unless overridden in options.
   *
   * @param {Object} options An object with the following properties
   * @param {String} [options.url]  The url that will be resolved relative to the url of the current instance.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be combined with those of the current instance.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}). These will be combined with those of the current instance.
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The function to call when loading the resource fails.
   * @param {Number} [options.retryAttempts] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {Boolean} [options.preserveQueryParameters=false] If true, this will keep all query parameters from the current resource and derived resource. If false, derived parameters will replace those of the current resource.
   *
   * @returns {Resource} The resource derived from the current one.
   */
  Resource.prototype.getDerivedResource = function (options) {
    var resource = this.clone();
    resource._retryCount = 0;

    if (defined(options.url)) {
      var uri = new URI(options.url);

      var preserveQueryParameters = defaultValue(
        options.preserveQueryParameters,
        false
      );
      parseQuery(uri, resource, true, preserveQueryParameters);

      // Remove the fragment as it's not sent with a request
      uri.fragment = undefined;

      resource._url = uri.resolve(new URI(getAbsoluteUri(this._url))).toString();
    }

    if (defined(options.queryParameters)) {
      resource._queryParameters = combine(
        options.queryParameters,
        resource._queryParameters
      );
    }
    if (defined(options.templateValues)) {
      resource._templateValues = combine(
        options.templateValues,
        resource.templateValues
      );
    }
    if (defined(options.headers)) {
      resource.headers = combine(options.headers, resource.headers);
    }
    if (defined(options.proxy)) {
      resource.proxy = options.proxy;
    }
    if (defined(options.request)) {
      resource.request = options.request;
    }
    if (defined(options.retryCallback)) {
      resource.retryCallback = options.retryCallback;
    }
    if (defined(options.retryAttempts)) {
      resource.retryAttempts = options.retryAttempts;
    }

    return resource;
  };

  /**
   * Called when a resource fails to load. This will call the retryCallback function if defined until retryAttempts is reached.
   *
   * @param {Error} [error] The error that was encountered.
   *
   * @returns {Promise<Boolean>} A promise to a boolean, that if true will cause the resource request to be retried.
   *
   * @private
   */
  Resource.prototype.retryOnError = function (error) {
    var retryCallback = this.retryCallback;
    if (
      typeof retryCallback !== "function" ||
      this._retryCount >= this.retryAttempts
    ) {
      return when(false);
    }

    var that = this;
    return when(retryCallback(this, error)).then(function (result) {
      ++that._retryCount;

      return result;
    });
  };

  /**
   * Duplicates a Resource instance.
   *
   * @param {Resource} [result] The object onto which to store the result.
   *
   * @returns {Resource} The modified result parameter or a new Resource instance if one was not provided.
   */
  Resource.prototype.clone = function (result) {
    if (!defined(result)) {
      result = new Resource({
        url: this._url,
      });
    }

    result._url = this._url;
    result._queryParameters = clone(this._queryParameters);
    result._templateValues = clone(this._templateValues);
    result.headers = clone(this.headers);
    result.proxy = this.proxy;
    result.retryCallback = this.retryCallback;
    result.retryAttempts = this.retryAttempts;
    result._retryCount = 0;
    result.request = this.request.clone();

    return result;
  };

  /**
   * Returns the base path of the Resource.
   *
   * @param {Boolean} [includeQuery = false] Whether or not to include the query string and fragment form the uri
   *
   * @returns {String} The base URI of the resource
   */
  Resource.prototype.getBaseUri = function (includeQuery) {
    return getBaseUri(this.getUrlComponent(includeQuery), includeQuery);
  };

  /**
   * Appends a forward slash to the URL.
   */
  Resource.prototype.appendForwardSlash = function () {
    this._url = appendForwardSlash(this._url);
  };

  /**
   * Asynchronously loads the resource as raw binary data.  Returns a promise that will resolve to
   * an ArrayBuffer once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @returns {Promise.<ArrayBuffer>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   * @example
   * // load a single URL asynchronously
   * resource.fetchArrayBuffer().then(function(arrayBuffer) {
   *     // use the data
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchArrayBuffer = function () {
    return this.fetch({
      responseType: "arraybuffer",
    });
  };

  /**
   * Creates a Resource and calls fetchArrayBuffer() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @returns {Promise.<ArrayBuffer>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchArrayBuffer = function (options) {
    var resource = new Resource(options);
    return resource.fetchArrayBuffer();
  };

  /**
   * Asynchronously loads the given resource as a blob.  Returns a promise that will resolve to
   * a Blob once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @returns {Promise.<Blob>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   * @example
   * // load a single URL asynchronously
   * resource.fetchBlob().then(function(blob) {
   *     // use the data
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchBlob = function () {
    return this.fetch({
      responseType: "blob",
    });
  };

  /**
   * Creates a Resource and calls fetchBlob() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @returns {Promise.<Blob>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchBlob = function (options) {
    var resource = new Resource(options);
    return resource.fetchBlob();
  };

  /**
   * Asynchronously loads the given image resource.  Returns a promise that will resolve to
   * an {@link https://developer.mozilla.org/en-US/docs/Web/API/ImageBitmap|ImageBitmap} if <code>preferImageBitmap</code> is true and the browser supports <code>createImageBitmap</code> or otherwise an
   * {@link https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement|Image} once loaded, or reject if the image failed to load.
   *
   * @param {Object} [options] An object with the following properties.
   * @param {Boolean} [options.preferBlob=false] If true, we will load the image via a blob.
   * @param {Boolean} [options.preferImageBitmap=false] If true, image will be decoded during fetch and an <code>ImageBitmap</code> is returned.
   * @param {Boolean} [options.flipY=false] If true, image will be vertically flipped during decode. Only applies if the browser supports <code>createImageBitmap</code>.
   * @returns {Promise.<ImageBitmap>|Promise.<HTMLImageElement>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * // load a single image asynchronously
   * resource.fetchImage().then(function(image) {
   *     // use the loaded image
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * // load several images in parallel
   * when.all([resource1.fetchImage(), resource2.fetchImage()]).then(function(images) {
   *     // images is an array containing all the loaded images
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchImage = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var preferImageBitmap = defaultValue(options.preferImageBitmap, false);
    var preferBlob = defaultValue(options.preferBlob, false);
    var flipY = defaultValue(options.flipY, false);

    checkAndResetRequest(this.request);

    // We try to load the image normally if
    // 1. Blobs aren't supported
    // 2. It's a data URI
    // 3. It's a blob URI
    // 4. It doesn't have request headers and we preferBlob is false
    if (
      !xhrBlobSupported ||
      this.isDataUri ||
      this.isBlobUri ||
      (!this.hasHeaders && !preferBlob)
    ) {
      return fetchImage({
        resource: this,
        flipY: flipY,
        preferImageBitmap: preferImageBitmap,
      });
    }

    var blobPromise = this.fetchBlob();
    if (!defined(blobPromise)) {
      return;
    }

    var supportsImageBitmap;
    var useImageBitmap;
    var generatedBlobResource;
    var generatedBlob;
    return Resource.supportsImageBitmapOptions()
      .then(function (result) {
        supportsImageBitmap = result;
        useImageBitmap = supportsImageBitmap && preferImageBitmap;
        return blobPromise;
      })
      .then(function (blob) {
        if (!defined(blob)) {
          return;
        }
        generatedBlob = blob;
        if (useImageBitmap) {
          return Resource.createImageBitmapFromBlob(blob, {
            flipY: flipY,
            premultiplyAlpha: false,
          });
        }
        var blobUrl = window.URL.createObjectURL(blob);
        generatedBlobResource = new Resource({
          url: blobUrl,
        });

        return fetchImage({
          resource: generatedBlobResource,
          flipY: flipY,
          preferImageBitmap: false,
        });
      })
      .then(function (image) {
        if (!defined(image)) {
          return;
        }

        // The blob object may be needed for use by a TileDiscardPolicy,
        // so attach it to the image.
        image.blob = generatedBlob;

        if (useImageBitmap) {
          return image;
        }

        window.URL.revokeObjectURL(generatedBlobResource.url);
        return image;
      })
      .otherwise(function (error) {
        if (defined(generatedBlobResource)) {
          window.URL.revokeObjectURL(generatedBlobResource.url);
        }

        // If the blob load succeeded but the image decode failed, attach the blob
        // to the error object for use by a TileDiscardPolicy.
        // In particular, BingMapsImageryProvider uses this to detect the
        // zero-length response that is returned when a tile is not available.
        error.blob = generatedBlob;

        return when.reject(error);
      });
  };

  /**
   * Fetches an image and returns a promise to it.
   *
   * @param {Object} [options] An object with the following properties.
   * @param {Resource} [options.resource] Resource object that points to an image to fetch.
   * @param {Boolean} [options.preferImageBitmap] If true, image will be decoded during fetch and an <code>ImageBitmap</code> is returned.
   * @param {Boolean} [options.flipY] If true, image will be vertically flipped during decode. Only applies if the browser supports <code>createImageBitmap</code>.
   *
   * @private
   */
  function fetchImage(options) {
    var resource = options.resource;
    var flipY = options.flipY;
    var preferImageBitmap = options.preferImageBitmap;

    var request = resource.request;
    request.url = resource.url;
    request.requestFunction = function () {
      var crossOrigin = false;

      // data URIs can't have crossorigin set.
      if (!resource.isDataUri && !resource.isBlobUri) {
        crossOrigin = resource.isCrossOriginUrl;
      }

      var deferred = when.defer();
      Resource._Implementations.createImage(
        request,
        crossOrigin,
        deferred,
        flipY,
        preferImageBitmap
      );

      return deferred.promise;
    };

    var promise = RequestScheduler.request(request);
    if (!defined(promise)) {
      return;
    }

    return promise.otherwise(function (e) {
      // Don't retry cancelled or otherwise aborted requests
      if (request.state !== RequestState$1.FAILED) {
        return when.reject(e);
      }

      return resource.retryOnError(e).then(function (retry) {
        if (retry) {
          // Reset request so it can try again
          request.state = RequestState$1.UNISSUED;
          request.deferred = undefined;

          return fetchImage({
            resource: resource,
            flipY: flipY,
            preferImageBitmap: preferImageBitmap,
          });
        }

        return when.reject(e);
      });
    });
  }

  /**
   * Creates a Resource and calls fetchImage() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Boolean} [options.flipY=false] Whether to vertically flip the image during fetch and decode. Only applies when requesting an image and the browser supports <code>createImageBitmap</code>.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {Boolean} [options.preferBlob=false]  If true, we will load the image via a blob.
   * @param {Boolean} [options.preferImageBitmap=false] If true, image will be decoded during fetch and an <code>ImageBitmap</code> is returned.
   * @returns {Promise.<ImageBitmap>|Promise.<HTMLImageElement>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchImage = function (options) {
    var resource = new Resource(options);
    return resource.fetchImage({
      flipY: options.flipY,
      preferBlob: options.preferBlob,
      preferImageBitmap: options.preferImageBitmap,
    });
  };

  /**
   * Asynchronously loads the given resource as text.  Returns a promise that will resolve to
   * a String once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @returns {Promise.<String>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   * @example
   * // load text from a URL, setting a custom header
   * var resource = new Resource({
   *   url: 'http://someUrl.com/someJson.txt',
   *   headers: {
   *     'X-Custom-Header' : 'some value'
   *   }
   * });
   * resource.fetchText().then(function(text) {
   *     // Do something with the text
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest|XMLHttpRequest}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchText = function () {
    return this.fetch({
      responseType: "text",
    });
  };

  /**
   * Creates a Resource and calls fetchText() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @returns {Promise.<String>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchText = function (options) {
    var resource = new Resource(options);
    return resource.fetchText();
  };

  // note: &#42;&#47;&#42; below is */* but that ends the comment block early
  /**
   * Asynchronously loads the given resource as JSON.  Returns a promise that will resolve to
   * a JSON object once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled. This function
   * adds 'Accept: application/json,&#42;&#47;&#42;;q=0.01' to the request headers, if not
   * already specified.
   *
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.fetchJson().then(function(jsonData) {
   *     // Do something with the JSON object
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchJson = function () {
    var promise = this.fetch({
      responseType: "text",
      headers: {
        Accept: "application/json,*/*;q=0.01",
      },
    });

    if (!defined(promise)) {
      return undefined;
    }

    return promise.then(function (value) {
      if (!defined(value)) {
        return;
      }
      return JSON.parse(value);
    });
  };

  /**
   * Creates a Resource and calls fetchJson() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchJson = function (options) {
    var resource = new Resource(options);
    return resource.fetchJson();
  };

  /**
   * Asynchronously loads the given resource as XML.  Returns a promise that will resolve to
   * an XML Document once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @returns {Promise.<XMLDocument>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * // load XML from a URL, setting a custom header
   * Cesium.loadXML('http://someUrl.com/someXML.xml', {
   *   'X-Custom-Header' : 'some value'
   * }).then(function(document) {
   *     // Do something with the document
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest|XMLHttpRequest}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchXML = function () {
    return this.fetch({
      responseType: "document",
      overrideMimeType: "text/xml",
    });
  };

  /**
   * Creates a Resource and calls fetchXML() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @returns {Promise.<XMLDocument>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchXML = function (options) {
    var resource = new Resource(options);
    return resource.fetchXML();
  };

  /**
   * Requests a resource using JSONP.
   *
   * @param {String} [callbackParameterName='callback'] The callback parameter name that the server expects.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * // load a data asynchronously
   * resource.fetchJsonp().then(function(data) {
   *     // use the loaded data
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetchJsonp = function (callbackParameterName) {
    callbackParameterName = defaultValue(callbackParameterName, "callback");

    checkAndResetRequest(this.request);

    //generate a unique function name
    var functionName;
    do {
      functionName = "loadJsonp" + Math.random().toString().substring(2, 8);
    } while (defined(window[functionName]));

    return fetchJsonp(this, callbackParameterName, functionName);
  };

  function fetchJsonp(resource, callbackParameterName, functionName) {
    var callbackQuery = {};
    callbackQuery[callbackParameterName] = functionName;
    resource.setQueryParameters(callbackQuery);

    var request = resource.request;
    request.url = resource.url;
    request.requestFunction = function () {
      var deferred = when.defer();

      //assign a function with that name in the global scope
      window[functionName] = function (data) {
        deferred.resolve(data);

        try {
          delete window[functionName];
        } catch (e) {
          window[functionName] = undefined;
        }
      };

      Resource._Implementations.loadAndExecuteScript(
        resource.url,
        functionName,
        deferred
      );
      return deferred.promise;
    };

    var promise = RequestScheduler.request(request);
    if (!defined(promise)) {
      return;
    }

    return promise.otherwise(function (e) {
      if (request.state !== RequestState$1.FAILED) {
        return when.reject(e);
      }

      return resource.retryOnError(e).then(function (retry) {
        if (retry) {
          // Reset request so it can try again
          request.state = RequestState$1.UNISSUED;
          request.deferred = undefined;

          return fetchJsonp(resource, callbackParameterName, functionName);
        }

        return when.reject(e);
      });
    });
  }

  /**
   * Creates a Resource from a URL and calls fetchJsonp() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.callbackParameterName='callback'] The callback parameter name that the server expects.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetchJsonp = function (options) {
    var resource = new Resource(options);
    return resource.fetchJsonp(options.callbackParameterName);
  };

  /**
   * @private
   */
  Resource.prototype._makeRequest = function (options) {
    var resource = this;
    checkAndResetRequest(resource.request);

    var request = resource.request;
    request.url = resource.url;

    request.requestFunction = function () {
      var responseType = options.responseType;
      var headers = combine(options.headers, resource.headers);
      var overrideMimeType = options.overrideMimeType;
      var method = options.method;
      var data = options.data;
      var deferred = when.defer();
      var xhr = Resource._Implementations.loadWithXhr(
        resource.url,
        responseType,
        method,
        data,
        headers,
        deferred,
        overrideMimeType
      );
      if (defined(xhr) && defined(xhr.abort)) {
        request.cancelFunction = function () {
          xhr.abort();
        };
      }
      return deferred.promise;
    };

    var promise = RequestScheduler.request(request);
    if (!defined(promise)) {
      return;
    }

    return promise
      .then(function (data) {
        // explicitly set to undefined to ensure GC of request response data. See #8843
        request.cancelFunction = undefined;
        return data;
      })
      .otherwise(function (e) {
        request.cancelFunction = undefined;
        if (request.state !== RequestState$1.FAILED) {
          return when.reject(e);
        }

        return resource.retryOnError(e).then(function (retry) {
          if (retry) {
            // Reset request so it can try again
            request.state = RequestState$1.UNISSUED;
            request.deferred = undefined;

            return resource.fetch(options);
          }

          return when.reject(e);
        });
      });
  };

  var dataUriRegex$1 = /^data:(.*?)(;base64)?,(.*)$/;

  function decodeDataUriText(isBase64, data) {
    var result = decodeURIComponent(data);
    if (isBase64) {
      return atob(result);
    }
    return result;
  }

  function decodeDataUriArrayBuffer(isBase64, data) {
    var byteString = decodeDataUriText(isBase64, data);
    var buffer = new ArrayBuffer(byteString.length);
    var view = new Uint8Array(buffer);
    for (var i = 0; i < byteString.length; i++) {
      view[i] = byteString.charCodeAt(i);
    }
    return buffer;
  }

  function decodeDataUri(dataUriRegexResult, responseType) {
    responseType = defaultValue(responseType, "");
    var mimeType = dataUriRegexResult[1];
    var isBase64 = !!dataUriRegexResult[2];
    var data = dataUriRegexResult[3];

    switch (responseType) {
      case "":
      case "text":
        return decodeDataUriText(isBase64, data);
      case "arraybuffer":
        return decodeDataUriArrayBuffer(isBase64, data);
      case "blob":
        var buffer = decodeDataUriArrayBuffer(isBase64, data);
        return new Blob([buffer], {
          type: mimeType,
        });
      case "document":
        var parser = new DOMParser();
        return parser.parseFromString(
          decodeDataUriText(isBase64, data),
          mimeType
        );
      case "json":
        return JSON.parse(decodeDataUriText(isBase64, data));
      default:
        //>>includeStart('debug', pragmas.debug);
        throw new DeveloperError("Unhandled responseType: " + responseType);
      //>>includeEnd('debug');
    }
  }

  /**
   * Asynchronously loads the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled. It's recommended that you use
   * the more specific functions eg. fetchJson, fetchBlob, etc.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.fetch()
   *   .then(function(body) {
   *       // use the data
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.fetch = function (options) {
    options = defaultClone(options, {});
    options.method = "GET";

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls fetch() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.fetch = function (options) {
    var resource = new Resource(options);
    return resource.fetch({
      // Make copy of just the needed fields because headers can be passed to both the constructor and to fetch
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
    });
  };

  /**
   * Asynchronously deletes the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.delete()
   *   .then(function(body) {
   *       // use the data
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.delete = function (options) {
    options = defaultClone(options, {});
    options.method = "DELETE";

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls delete() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.data] Data that is posted with the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.delete = function (options) {
    var resource = new Resource(options);
    return resource.delete({
      // Make copy of just the needed fields because headers can be passed to both the constructor and to fetch
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
      data: options.data,
    });
  };

  /**
   * Asynchronously gets headers the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.head()
   *   .then(function(headers) {
   *       // use the data
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.head = function (options) {
    options = defaultClone(options, {});
    options.method = "HEAD";

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls head() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.head = function (options) {
    var resource = new Resource(options);
    return resource.head({
      // Make copy of just the needed fields because headers can be passed to both the constructor and to fetch
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
    });
  };

  /**
   * Asynchronously gets options the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.options()
   *   .then(function(headers) {
   *       // use the data
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.options = function (options) {
    options = defaultClone(options, {});
    options.method = "OPTIONS";

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls options() on it.
   *
   * @param {String|Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.options = function (options) {
    var resource = new Resource(options);
    return resource.options({
      // Make copy of just the needed fields because headers can be passed to both the constructor and to fetch
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
    });
  };

  /**
   * Asynchronously posts data to the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @param {Object} data Data that is posted with the resource.
   * @param {Object} [options] Object with the following properties:
   * @param {Object} [options.data] Data that is posted with the resource.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.post(data)
   *   .then(function(result) {
   *       // use the result
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.post = function (data, options) {
    Check.defined("data", data);

    options = defaultClone(options, {});
    options.method = "POST";
    options.data = data;

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls post() on it.
   *
   * @param {Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} options.data Data that is posted with the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.post = function (options) {
    var resource = new Resource(options);
    return resource.post(options.data, {
      // Make copy of just the needed fields because headers can be passed to both the constructor and to post
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
    });
  };

  /**
   * Asynchronously puts data to the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @param {Object} data Data that is posted with the resource.
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.put(data)
   *   .then(function(result) {
   *       // use the result
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.put = function (data, options) {
    Check.defined("data", data);

    options = defaultClone(options, {});
    options.method = "PUT";
    options.data = data;

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls put() on it.
   *
   * @param {Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} options.data Data that is posted with the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.put = function (options) {
    var resource = new Resource(options);
    return resource.put(options.data, {
      // Make copy of just the needed fields because headers can be passed to both the constructor and to post
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
    });
  };

  /**
   * Asynchronously patches data to the given resource.  Returns a promise that will resolve to
   * the result once loaded, or reject if the resource failed to load.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @param {Object} data Data that is posted with the resource.
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {Object} [options.headers] Additional HTTP headers to send with the request, if any.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   *
   * @example
   * resource.patch(data)
   *   .then(function(result) {
   *       // use the result
   *   }).otherwise(function(error) {
   *       // an error occurred
   *   });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  Resource.prototype.patch = function (data, options) {
    Check.defined("data", data);

    options = defaultClone(options, {});
    options.method = "PATCH";
    options.data = data;

    return this._makeRequest(options);
  };

  /**
   * Creates a Resource from a URL and calls patch() on it.
   *
   * @param {Object} options A url or an object with the following properties
   * @param {String} options.url The url of the resource.
   * @param {Object} options.data Data that is posted with the resource.
   * @param {Object} [options.queryParameters] An object containing query parameters that will be sent when retrieving the resource.
   * @param {Object} [options.templateValues] Key/Value pairs that are used to replace template values (eg. {x}).
   * @param {Object} [options.headers={}] Additional HTTP headers that will be sent.
   * @param {Proxy} [options.proxy] A proxy to be used when loading the resource.
   * @param {Resource.RetryCallback} [options.retryCallback] The Function to call when a request for this resource fails. If it returns true, the request will be retried.
   * @param {Number} [options.retryAttempts=0] The number of times the retryCallback should be called before giving up.
   * @param {Request} [options.request] A Request object that will be used. Intended for internal use only.
   * @param {String} [options.responseType] The type of response.  This controls the type of item returned.
   * @param {String} [options.overrideMimeType] Overrides the MIME type returned by the server.
   * @returns {Promise.<*>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   */
  Resource.patch = function (options) {
    var resource = new Resource(options);
    return resource.patch(options.data, {
      // Make copy of just the needed fields because headers can be passed to both the constructor and to post
      responseType: options.responseType,
      overrideMimeType: options.overrideMimeType,
    });
  };

  /**
   * Contains implementations of functions that can be replaced for testing
   *
   * @private
   */
  Resource._Implementations = {};

  function loadImageElement(url, crossOrigin, deferred) {
    var image = new Image();

    image.onload = function () {
      deferred.resolve(image);
    };

    image.onerror = function (e) {
      deferred.reject(e);
    };

    if (crossOrigin) {
      if (TrustedServers.contains(url)) {
        image.crossOrigin = "use-credentials";
      } else {
        image.crossOrigin = "";
      }
    }

    image.src = url;
  }

  Resource._Implementations.createImage = function (
    request,
    crossOrigin,
    deferred,
    flipY,
    preferImageBitmap
  ) {
    var url = request.url;
    // Passing an Image to createImageBitmap will force it to run on the main thread
    // since DOM elements don't exist on workers. We convert it to a blob so it's non-blocking.
    // See:
    //    https://bugzilla.mozilla.org/show_bug.cgi?id=1044102#c38
    //    https://bugs.chromium.org/p/chromium/issues/detail?id=580202#c10
    Resource.supportsImageBitmapOptions()
      .then(function (supportsImageBitmap) {
        // We can only use ImageBitmap if we can flip on decode.
        // See: https://github.com/CesiumGS/cesium/pull/7579#issuecomment-466146898
        if (!(supportsImageBitmap && preferImageBitmap)) {
          loadImageElement(url, crossOrigin, deferred);
          return;
        }
        var responseType = "blob";
        var method = "GET";
        var xhrDeferred = when.defer();
        var xhr = Resource._Implementations.loadWithXhr(
          url,
          responseType,
          method,
          undefined,
          undefined,
          xhrDeferred,
          undefined,
          undefined,
          undefined
        );

        if (defined(xhr) && defined(xhr.abort)) {
          request.cancelFunction = function () {
            xhr.abort();
          };
        }
        return xhrDeferred.promise
          .then(function (blob) {
            if (!defined(blob)) {
              deferred.reject(
                new RuntimeError(
                  "Successfully retrieved " +
                    url +
                    " but it contained no content."
                )
              );
              return;
            }

            return Resource.createImageBitmapFromBlob(blob, {
              flipY: flipY,
              premultiplyAlpha: false,
            });
          })
          .then(deferred.resolve);
      })
      .otherwise(deferred.reject);
  };

  /**
   * Wrapper for createImageBitmap
   *
   * @private
   */
  Resource.createImageBitmapFromBlob = function (blob, options) {
    Check.defined("options", options);
    Check.typeOf.bool("options.flipY", options.flipY);
    Check.typeOf.bool("options.premultiplyAlpha", options.premultiplyAlpha);

    return createImageBitmap(blob, {
      imageOrientation: options.flipY ? "flipY" : "none",
      premultiplyAlpha: options.premultiplyAlpha ? "premultiply" : "none",
    });
  };

  function decodeResponse(loadWithHttpResponse, responseType) {
    switch (responseType) {
      case "text":
        return loadWithHttpResponse.toString("utf8");
      case "json":
        return JSON.parse(loadWithHttpResponse.toString("utf8"));
      default:
        return new Uint8Array(loadWithHttpResponse).buffer;
    }
  }

  function loadWithHttpRequest(
    url,
    responseType,
    method,
    data,
    headers,
    deferred,
    overrideMimeType
  ) {
    // Note: only the 'json' and 'text' responseTypes transforms the loaded buffer
    /* eslint-disable no-undef */
    var URL = require("url").parse(url);
    var http = URL.protocol === "https:" ? require("https") : require("http");
    var zlib = require("zlib");
    /* eslint-enable no-undef */

    var options = {
      protocol: URL.protocol,
      hostname: URL.hostname,
      port: URL.port,
      path: URL.path,
      query: URL.query,
      method: method,
      headers: headers,
    };

    http
      .request(options)
      .on("response", function (res) {
        if (res.statusCode < 200 || res.statusCode >= 300) {
          deferred.reject(
            new RequestErrorEvent(res.statusCode, res, res.headers)
          );
          return;
        }

        var chunkArray = [];
        res.on("data", function (chunk) {
          chunkArray.push(chunk);
        });

        res.on("end", function () {
          // eslint-disable-next-line no-undef
          var result = Buffer.concat(chunkArray);
          if (res.headers["content-encoding"] === "gzip") {
            zlib.gunzip(result, function (error, resultUnzipped) {
              if (error) {
                deferred.reject(
                  new RuntimeError("Error decompressing response.")
                );
              } else {
                deferred.resolve(decodeResponse(resultUnzipped, responseType));
              }
            });
          } else {
            deferred.resolve(decodeResponse(result, responseType));
          }
        });
      })
      .on("error", function (e) {
        deferred.reject(new RequestErrorEvent());
      })
      .end();
  }

  var noXMLHttpRequest = typeof XMLHttpRequest === "undefined";
  Resource._Implementations.loadWithXhr = function (
    url,
    responseType,
    method,
    data,
    headers,
    deferred,
    overrideMimeType
  ) {
    var dataUriRegexResult = dataUriRegex$1.exec(url);
    if (dataUriRegexResult !== null) {
      deferred.resolve(decodeDataUri(dataUriRegexResult, responseType));
      return;
    }

    if (noXMLHttpRequest) {
      loadWithHttpRequest(
        url,
        responseType,
        method,
        data,
        headers,
        deferred);
      return;
    }

    var xhr = new XMLHttpRequest();

    if (TrustedServers.contains(url)) {
      xhr.withCredentials = true;
    }

    xhr.open(method, url, true);

    if (defined(overrideMimeType) && defined(xhr.overrideMimeType)) {
      xhr.overrideMimeType(overrideMimeType);
    }

    if (defined(headers)) {
      for (var key in headers) {
        if (headers.hasOwnProperty(key)) {
          xhr.setRequestHeader(key, headers[key]);
        }
      }
    }

    if (defined(responseType)) {
      xhr.responseType = responseType;
    }

    // While non-standard, file protocol always returns a status of 0 on success
    var localFile = false;
    if (typeof url === "string") {
      localFile =
        url.indexOf("file://") === 0 ||
        (typeof window !== "undefined" && window.location.origin === "file://");
    }

    xhr.onload = function () {
      if (
        (xhr.status < 200 || xhr.status >= 300) &&
        !(localFile && xhr.status === 0)
      ) {
        deferred.reject(
          new RequestErrorEvent(
            xhr.status,
            xhr.response,
            xhr.getAllResponseHeaders()
          )
        );
        return;
      }

      var response = xhr.response;
      var browserResponseType = xhr.responseType;

      if (method === "HEAD" || method === "OPTIONS") {
        var responseHeaderString = xhr.getAllResponseHeaders();
        var splitHeaders = responseHeaderString.trim().split(/[\r\n]+/);

        var responseHeaders = {};
        splitHeaders.forEach(function (line) {
          var parts = line.split(": ");
          var header = parts.shift();
          responseHeaders[header] = parts.join(": ");
        });

        deferred.resolve(responseHeaders);
        return;
      }

      //All modern browsers will go into either the first or second if block or last else block.
      //Other code paths support older browsers that either do not support the supplied responseType
      //or do not support the xhr.response property.
      if (xhr.status === 204) {
        // accept no content
        deferred.resolve();
      } else if (
        defined(response) &&
        (!defined(responseType) || browserResponseType === responseType)
      ) {
        deferred.resolve(response);
      } else if (responseType === "json" && typeof response === "string") {
        try {
          deferred.resolve(JSON.parse(response));
        } catch (e) {
          deferred.reject(e);
        }
      } else if (
        (browserResponseType === "" || browserResponseType === "document") &&
        defined(xhr.responseXML) &&
        xhr.responseXML.hasChildNodes()
      ) {
        deferred.resolve(xhr.responseXML);
      } else if (
        (browserResponseType === "" || browserResponseType === "text") &&
        defined(xhr.responseText)
      ) {
        deferred.resolve(xhr.responseText);
      } else {
        deferred.reject(
          new RuntimeError("Invalid XMLHttpRequest response type.")
        );
      }
    };

    xhr.onerror = function (e) {
      deferred.reject(new RequestErrorEvent());
    };

    xhr.send(data);

    return xhr;
  };

  Resource._Implementations.loadAndExecuteScript = function (
    url,
    functionName,
    deferred
  ) {
    return loadAndExecuteScript(url).otherwise(deferred.reject);
  };

  /**
   * The default implementations
   *
   * @private
   */
  Resource._DefaultImplementations = {};
  Resource._DefaultImplementations.createImage =
    Resource._Implementations.createImage;
  Resource._DefaultImplementations.loadWithXhr =
    Resource._Implementations.loadWithXhr;
  Resource._DefaultImplementations.loadAndExecuteScript =
    Resource._Implementations.loadAndExecuteScript;

  /**
   * A resource instance initialized to the current browser location
   *
   * @type {Resource}
   * @constant
   */
  Resource.DEFAULT = Object.freeze(
    new Resource({
      url:
        typeof document === "undefined"
          ? ""
          : document.location.href.split("?")[0],
    })
  );

  /*global CESIUM_BASE_URL*/

  var cesiumScriptRegex = /((?:.*\/)|^)Cesium\.js(?:\?|\#|$)/;
  function getBaseUrlFromCesiumScript() {
    var scripts = document.getElementsByTagName("script");
    for (var i = 0, len = scripts.length; i < len; ++i) {
      var src = scripts[i].getAttribute("src");
      var result = cesiumScriptRegex.exec(src);
      if (result !== null) {
        return result[1];
      }
    }
    return undefined;
  }

  var a$1;
  function tryMakeAbsolute(url) {
    if (typeof document === "undefined") {
      //Node.js and Web Workers. In both cases, the URL will already be absolute.
      return url;
    }

    if (!defined(a$1)) {
      a$1 = document.createElement("a");
    }
    a$1.href = url;

    // IE only absolutizes href on get, not set
    // eslint-disable-next-line no-self-assign
    a$1.href = a$1.href;
    return a$1.href;
  }

  var baseResource;
  function getCesiumBaseUrl() {
    if (defined(baseResource)) {
      return baseResource;
    }

    var baseUrlString;
    if (typeof CESIUM_BASE_URL !== "undefined") {
      baseUrlString = CESIUM_BASE_URL;
    } else if (
      typeof define === "object" &&
      defined(define.amd) &&
      !define.amd.toUrlUndefined &&
      defined(require.toUrl)
    ) {
      baseUrlString = getAbsoluteUri(
        "..",
        buildModuleUrl("Core/buildModuleUrl.js")
      );
    } else {
      baseUrlString = getBaseUrlFromCesiumScript();
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(baseUrlString)) {
      throw new DeveloperError(
        "Unable to determine Cesium base URL automatically, try defining a global variable called CESIUM_BASE_URL."
      );
    }
    //>>includeEnd('debug');

    baseResource = new Resource({
      url: tryMakeAbsolute(baseUrlString),
    });
    baseResource.appendForwardSlash();

    return baseResource;
  }

  function buildModuleUrlFromRequireToUrl(moduleID) {
    //moduleID will be non-relative, so require it relative to this module, in Core.
    return tryMakeAbsolute(require.toUrl("../" + moduleID));
  }

  function buildModuleUrlFromBaseUrl(moduleID) {
    var resource = getCesiumBaseUrl().getDerivedResource({
      url: moduleID,
    });
    return resource.url;
  }

  var implementation;

  /**
   * Given a relative URL under the Cesium base URL, returns an absolute URL.
   * @function
   *
   * @param {String} relativeUrl The relative path.
   * @returns {String} The absolutely URL representation of the provided path.
   *
   * @example
   * var viewer = new Cesium.Viewer("cesiumContainer", {
   *   imageryProvider: new Cesium.TileMapServiceImageryProvider({
   *   url: Cesium.buildModuleUrl("Assets/Textures/NaturalEarthII"),
   *   }),
   *   baseLayerPicker: false,
   * });
   */
  function buildModuleUrl(relativeUrl) {
    if (!defined(implementation)) {
      //select implementation
      if (
        typeof define === "object" &&
        defined(define.amd) &&
        !define.amd.toUrlUndefined &&
        defined(require.toUrl)
      ) {
        implementation = buildModuleUrlFromRequireToUrl;
      } else {
        implementation = buildModuleUrlFromBaseUrl;
      }
    }

    var url = implementation(relativeUrl);
    return url;
  }

  // exposed for testing
  buildModuleUrl._cesiumScriptRegex = cesiumScriptRegex;
  buildModuleUrl._buildModuleUrlFromBaseUrl = buildModuleUrlFromBaseUrl;
  buildModuleUrl._clearBaseResource = function () {
    baseResource = undefined;
  };

  /**
   * Sets the base URL for resolving modules.
   * @param {String} value The new base URL.
   */
  buildModuleUrl.setBaseUrl = function (value) {
    baseResource = Resource.DEFAULT.getDerivedResource({
      url: value,
    });
  };

  /**
   * Gets the base URL for resolving modules.
   */
  buildModuleUrl.getCesiumBaseUrl = getCesiumBaseUrl;

  /**
   * A 2D Cartesian point.
   * @alias Cartesian2
   * @constructor
   *
   * @param {Number} [x=0.0] The X component.
   * @param {Number} [y=0.0] The Y component.
   *
   * @see Cartesian3
   * @see Cartesian4
   * @see Packable
   */
  function Cartesian2(x, y) {
    /**
     * The X component.
     * @type {Number}
     * @default 0.0
     */
    this.x = defaultValue(x, 0.0);

    /**
     * The Y component.
     * @type {Number}
     * @default 0.0
     */
    this.y = defaultValue(y, 0.0);
  }

  /**
   * Creates a Cartesian2 instance from x and y coordinates.
   *
   * @param {Number} x The x coordinate.
   * @param {Number} y The y coordinate.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.
   */
  Cartesian2.fromElements = function (x, y, result) {
    if (!defined(result)) {
      return new Cartesian2(x, y);
    }

    result.x = x;
    result.y = y;
    return result;
  };

  /**
   * Duplicates a Cartesian2 instance.
   *
   * @param {Cartesian2} cartesian The Cartesian to duplicate.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided. (Returns undefined if cartesian is undefined)
   */
  Cartesian2.clone = function (cartesian, result) {
    if (!defined(cartesian)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Cartesian2(cartesian.x, cartesian.y);
    }

    result.x = cartesian.x;
    result.y = cartesian.y;
    return result;
  };

  /**
   * Creates a Cartesian2 instance from an existing Cartesian3.  This simply takes the
   * x and y properties of the Cartesian3 and drops z.
   * @function
   *
   * @param {Cartesian3} cartesian The Cartesian3 instance to create a Cartesian2 instance from.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.
   */
  Cartesian2.fromCartesian3 = Cartesian2.clone;

  /**
   * Creates a Cartesian2 instance from an existing Cartesian4.  This simply takes the
   * x and y properties of the Cartesian4 and drops z and w.
   * @function
   *
   * @param {Cartesian4} cartesian The Cartesian4 instance to create a Cartesian2 instance from.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.
   */
  Cartesian2.fromCartesian4 = Cartesian2.clone;

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Cartesian2.packedLength = 2;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Cartesian2} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Cartesian2.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.x;
    array[startingIndex] = value.y;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Cartesian2} [result] The object into which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.
   */
  Cartesian2.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Cartesian2();
    }
    result.x = array[startingIndex++];
    result.y = array[startingIndex];
    return result;
  };

  /**
       * Flattens an array of Cartesian2s into and array of components.
       *
       * @param {Cartesian2[]} array The array of cartesians to pack.
       * @param {Number[]} [result] The array onto which to store the result. If this is a typed array, it must have array.length * 2 components, else a {@link DeveloperError} will be thrown. If it is a regular array, it will be resized to have (array.length * 2) elements.

       * @returns {Number[]} The packed array.
       */
  Cartesian2.packArray = function (array, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    var length = array.length;
    var resultLength = length * 2;
    if (!defined(result)) {
      result = new Array(resultLength);
    } else if (!Array.isArray(result) && result.length !== resultLength) {
      throw new DeveloperError(
        "If result is a typed array, it must have exactly array.length * 2 elements"
      );
    } else if (result.length !== resultLength) {
      result.length = resultLength;
    }

    for (var i = 0; i < length; ++i) {
      Cartesian2.pack(array[i], result, i * 2);
    }
    return result;
  };

  /**
   * Unpacks an array of cartesian components into and array of Cartesian2s.
   *
   * @param {Number[]} array The array of components to unpack.
   * @param {Cartesian2[]} [result] The array onto which to store the result.
   * @returns {Cartesian2[]} The unpacked array.
   */
  Cartesian2.unpackArray = function (array, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    Check.typeOf.number.greaterThanOrEquals("array.length", array.length, 2);
    if (array.length % 2 !== 0) {
      throw new DeveloperError("array length must be a multiple of 2.");
    }
    //>>includeEnd('debug');

    var length = array.length;
    if (!defined(result)) {
      result = new Array(length / 2);
    } else {
      result.length = length / 2;
    }

    for (var i = 0; i < length; i += 2) {
      var index = i / 2;
      result[index] = Cartesian2.unpack(array, i, result[index]);
    }
    return result;
  };

  /**
   * Creates a Cartesian2 from two consecutive elements in an array.
   * @function
   *
   * @param {Number[]} array The array whose two consecutive elements correspond to the x and y components, respectively.
   * @param {Number} [startingIndex=0] The offset into the array of the first element, which corresponds to the x component.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.
   *
   * @example
   * // Create a Cartesian2 with (1.0, 2.0)
   * var v = [1.0, 2.0];
   * var p = Cesium.Cartesian2.fromArray(v);
   *
   * // Create a Cartesian2 with (1.0, 2.0) using an offset into an array
   * var v2 = [0.0, 0.0, 1.0, 2.0];
   * var p2 = Cesium.Cartesian2.fromArray(v2, 2);
   */
  Cartesian2.fromArray = Cartesian2.unpack;

  /**
   * Computes the value of the maximum component for the supplied Cartesian.
   *
   * @param {Cartesian2} cartesian The cartesian to use.
   * @returns {Number} The value of the maximum component.
   */
  Cartesian2.maximumComponent = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return Math.max(cartesian.x, cartesian.y);
  };

  /**
   * Computes the value of the minimum component for the supplied Cartesian.
   *
   * @param {Cartesian2} cartesian The cartesian to use.
   * @returns {Number} The value of the minimum component.
   */
  Cartesian2.minimumComponent = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return Math.min(cartesian.x, cartesian.y);
  };

  /**
   * Compares two Cartesians and computes a Cartesian which contains the minimum components of the supplied Cartesians.
   *
   * @param {Cartesian2} first A cartesian to compare.
   * @param {Cartesian2} second A cartesian to compare.
   * @param {Cartesian2} result The object into which to store the result.
   * @returns {Cartesian2} A cartesian with the minimum components.
   */
  Cartesian2.minimumByComponent = function (first, second, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("first", first);
    Check.typeOf.object("second", second);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.min(first.x, second.x);
    result.y = Math.min(first.y, second.y);

    return result;
  };

  /**
   * Compares two Cartesians and computes a Cartesian which contains the maximum components of the supplied Cartesians.
   *
   * @param {Cartesian2} first A cartesian to compare.
   * @param {Cartesian2} second A cartesian to compare.
   * @param {Cartesian2} result The object into which to store the result.
   * @returns {Cartesian2} A cartesian with the maximum components.
   */
  Cartesian2.maximumByComponent = function (first, second, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("first", first);
    Check.typeOf.object("second", second);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.max(first.x, second.x);
    result.y = Math.max(first.y, second.y);
    return result;
  };

  /**
   * Computes the provided Cartesian's squared magnitude.
   *
   * @param {Cartesian2} cartesian The Cartesian instance whose squared magnitude is to be computed.
   * @returns {Number} The squared magnitude.
   */
  Cartesian2.magnitudeSquared = function (cartesian) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    return cartesian.x * cartesian.x + cartesian.y * cartesian.y;
  };

  /**
   * Computes the Cartesian's magnitude (length).
   *
   * @param {Cartesian2} cartesian The Cartesian instance whose magnitude is to be computed.
   * @returns {Number} The magnitude.
   */
  Cartesian2.magnitude = function (cartesian) {
    return Math.sqrt(Cartesian2.magnitudeSquared(cartesian));
  };

  var distanceScratch$2 = new Cartesian2();

  /**
   * Computes the distance between two points.
   *
   * @param {Cartesian2} left The first point to compute the distance from.
   * @param {Cartesian2} right The second point to compute the distance to.
   * @returns {Number} The distance between two points.
   *
   * @example
   * // Returns 1.0
   * var d = Cesium.Cartesian2.distance(new Cesium.Cartesian2(1.0, 0.0), new Cesium.Cartesian2(2.0, 0.0));
   */
  Cartesian2.distance = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian2.subtract(left, right, distanceScratch$2);
    return Cartesian2.magnitude(distanceScratch$2);
  };

  /**
   * Computes the squared distance between two points.  Comparing squared distances
   * using this function is more efficient than comparing distances using {@link Cartesian2#distance}.
   *
   * @param {Cartesian2} left The first point to compute the distance from.
   * @param {Cartesian2} right The second point to compute the distance to.
   * @returns {Number} The distance between two points.
   *
   * @example
   * // Returns 4.0, not 2.0
   * var d = Cesium.Cartesian2.distance(new Cesium.Cartesian2(1.0, 0.0), new Cesium.Cartesian2(3.0, 0.0));
   */
  Cartesian2.distanceSquared = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian2.subtract(left, right, distanceScratch$2);
    return Cartesian2.magnitudeSquared(distanceScratch$2);
  };

  /**
   * Computes the normalized form of the supplied Cartesian.
   *
   * @param {Cartesian2} cartesian The Cartesian to be normalized.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.normalize = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var magnitude = Cartesian2.magnitude(cartesian);

    result.x = cartesian.x / magnitude;
    result.y = cartesian.y / magnitude;

    //>>includeStart('debug', pragmas.debug);
    if (isNaN(result.x) || isNaN(result.y)) {
      throw new DeveloperError("normalized result is not a number");
    }
    //>>includeEnd('debug');

    return result;
  };

  /**
   * Computes the dot (scalar) product of two Cartesians.
   *
   * @param {Cartesian2} left The first Cartesian.
   * @param {Cartesian2} right The second Cartesian.
   * @returns {Number} The dot product.
   */
  Cartesian2.dot = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    return left.x * right.x + left.y * right.y;
  };

  /**
   * Computes the componentwise product of two Cartesians.
   *
   * @param {Cartesian2} left The first Cartesian.
   * @param {Cartesian2} right The second Cartesian.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.multiplyComponents = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x * right.x;
    result.y = left.y * right.y;
    return result;
  };

  /**
   * Computes the componentwise quotient of two Cartesians.
   *
   * @param {Cartesian2} left The first Cartesian.
   * @param {Cartesian2} right The second Cartesian.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.divideComponents = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x / right.x;
    result.y = left.y / right.y;
    return result;
  };

  /**
   * Computes the componentwise sum of two Cartesians.
   *
   * @param {Cartesian2} left The first Cartesian.
   * @param {Cartesian2} right The second Cartesian.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x + right.x;
    result.y = left.y + right.y;
    return result;
  };

  /**
   * Computes the componentwise difference of two Cartesians.
   *
   * @param {Cartesian2} left The first Cartesian.
   * @param {Cartesian2} right The second Cartesian.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x - right.x;
    result.y = left.y - right.y;
    return result;
  };

  /**
   * Multiplies the provided Cartesian componentwise by the provided scalar.
   *
   * @param {Cartesian2} cartesian The Cartesian to be scaled.
   * @param {Number} scalar The scalar to multiply with.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.multiplyByScalar = function (cartesian, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = cartesian.x * scalar;
    result.y = cartesian.y * scalar;
    return result;
  };

  /**
   * Divides the provided Cartesian componentwise by the provided scalar.
   *
   * @param {Cartesian2} cartesian The Cartesian to be divided.
   * @param {Number} scalar The scalar to divide by.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.divideByScalar = function (cartesian, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = cartesian.x / scalar;
    result.y = cartesian.y / scalar;
    return result;
  };

  /**
   * Negates the provided Cartesian.
   *
   * @param {Cartesian2} cartesian The Cartesian to be negated.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.negate = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = -cartesian.x;
    result.y = -cartesian.y;
    return result;
  };

  /**
   * Computes the absolute value of the provided Cartesian.
   *
   * @param {Cartesian2} cartesian The Cartesian whose absolute value is to be computed.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.abs = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Math.abs(cartesian.x);
    result.y = Math.abs(cartesian.y);
    return result;
  };

  var lerpScratch$2 = new Cartesian2();
  /**
   * Computes the linear interpolation or extrapolation at t using the provided cartesians.
   *
   * @param {Cartesian2} start The value corresponding to t at 0.0.
   * @param {Cartesian2} end The value corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Cartesian2.lerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    Cartesian2.multiplyByScalar(end, t, lerpScratch$2);
    result = Cartesian2.multiplyByScalar(start, 1.0 - t, result);
    return Cartesian2.add(lerpScratch$2, result, result);
  };

  var angleBetweenScratch$1 = new Cartesian2();
  var angleBetweenScratch2$1 = new Cartesian2();
  /**
   * Returns the angle, in radians, between the provided Cartesians.
   *
   * @param {Cartesian2} left The first Cartesian.
   * @param {Cartesian2} right The second Cartesian.
   * @returns {Number} The angle between the Cartesians.
   */
  Cartesian2.angleBetween = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    Cartesian2.normalize(left, angleBetweenScratch$1);
    Cartesian2.normalize(right, angleBetweenScratch2$1);
    return CesiumMath.acosClamped(
      Cartesian2.dot(angleBetweenScratch$1, angleBetweenScratch2$1)
    );
  };

  var mostOrthogonalAxisScratch$2 = new Cartesian2();
  /**
   * Returns the axis that is most orthogonal to the provided Cartesian.
   *
   * @param {Cartesian2} cartesian The Cartesian on which to find the most orthogonal axis.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The most orthogonal axis.
   */
  Cartesian2.mostOrthogonalAxis = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var f = Cartesian2.normalize(cartesian, mostOrthogonalAxisScratch$2);
    Cartesian2.abs(f, f);

    if (f.x <= f.y) {
      result = Cartesian2.clone(Cartesian2.UNIT_X, result);
    } else {
      result = Cartesian2.clone(Cartesian2.UNIT_Y, result);
    }

    return result;
  };

  /**
   * Compares the provided Cartesians componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartesian2} [left] The first Cartesian.
   * @param {Cartesian2} [right] The second Cartesian.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Cartesian2.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.x === right.x &&
        left.y === right.y)
    );
  };

  /**
   * @private
   */
  Cartesian2.equalsArray = function (cartesian, array, offset) {
    return cartesian.x === array[offset] && cartesian.y === array[offset + 1];
  };

  /**
   * Compares the provided Cartesians componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Cartesian2} [left] The first Cartesian.
   * @param {Cartesian2} [right] The second Cartesian.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartesian2.equalsEpsilon = function (
    left,
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        CesiumMath.equalsEpsilon(
          left.x,
          right.x,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.y,
          right.y,
          relativeEpsilon,
          absoluteEpsilon
        ))
    );
  };

  /**
   * An immutable Cartesian2 instance initialized to (0.0, 0.0).
   *
   * @type {Cartesian2}
   * @constant
   */
  Cartesian2.ZERO = Object.freeze(new Cartesian2(0.0, 0.0));

  /**
   * An immutable Cartesian2 instance initialized to (1.0, 0.0).
   *
   * @type {Cartesian2}
   * @constant
   */
  Cartesian2.UNIT_X = Object.freeze(new Cartesian2(1.0, 0.0));

  /**
   * An immutable Cartesian2 instance initialized to (0.0, 1.0).
   *
   * @type {Cartesian2}
   * @constant
   */
  Cartesian2.UNIT_Y = Object.freeze(new Cartesian2(0.0, 1.0));

  /**
   * Duplicates this Cartesian2 instance.
   *
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.
   */
  Cartesian2.prototype.clone = function (result) {
    return Cartesian2.clone(this, result);
  };

  /**
   * Compares this Cartesian against the provided Cartesian componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Cartesian2} [right] The right hand side Cartesian.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Cartesian2.prototype.equals = function (right) {
    return Cartesian2.equals(this, right);
  };

  /**
   * Compares this Cartesian against the provided Cartesian componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {Cartesian2} [right] The right hand side Cartesian.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  Cartesian2.prototype.equalsEpsilon = function (
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return Cartesian2.equalsEpsilon(
      this,
      right,
      relativeEpsilon,
      absoluteEpsilon
    );
  };

  /**
   * Creates a string representing this Cartesian in the format '(x, y)'.
   *
   * @returns {String} A string representing the provided Cartesian in the format '(x, y)'.
   */
  Cartesian2.prototype.toString = function () {
    return "(" + this.x + ", " + this.y + ")";
  };

  /**
   * A tiling scheme for geometry referenced to a simple {@link GeographicProjection} where
   * longitude and latitude are directly mapped to X and Y.  This projection is commonly
   * known as geographic, equirectangular, equidistant cylindrical, or plate carrée.
   *
   * @alias GeographicTilingScheme
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid whose surface is being tiled. Defaults to
   * the WGS84 ellipsoid.
   * @param {Rectangle} [options.rectangle=Rectangle.MAX_VALUE] The rectangle, in radians, covered by the tiling scheme.
   * @param {Number} [options.numberOfLevelZeroTilesX=2] The number of tiles in the X direction at level zero of
   * the tile tree.
   * @param {Number} [options.numberOfLevelZeroTilesY=1] The number of tiles in the Y direction at level zero of
   * the tile tree.
   */
  function GeographicTilingScheme(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    this._rectangle = defaultValue(options.rectangle, Rectangle.MAX_VALUE);
    this._projection = new GeographicProjection(this._ellipsoid);
    this._numberOfLevelZeroTilesX = defaultValue(
      options.numberOfLevelZeroTilesX,
      2
    );
    this._numberOfLevelZeroTilesY = defaultValue(
      options.numberOfLevelZeroTilesY,
      1
    );
  }

  Object.defineProperties(GeographicTilingScheme.prototype, {
    /**
     * Gets the ellipsoid that is tiled by this tiling scheme.
     * @memberof GeographicTilingScheme.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },

    /**
     * Gets the rectangle, in radians, covered by this tiling scheme.
     * @memberof GeographicTilingScheme.prototype
     * @type {Rectangle}
     */
    rectangle: {
      get: function () {
        return this._rectangle;
      },
    },

    /**
     * Gets the map projection used by this tiling scheme.
     * @memberof GeographicTilingScheme.prototype
     * @type {MapProjection}
     */
    projection: {
      get: function () {
        return this._projection;
      },
    },
  });

  /**
   * Gets the total number of tiles in the X direction at a specified level-of-detail.
   *
   * @param {Number} level The level-of-detail.
   * @returns {Number} The number of tiles in the X direction at the given level.
   */
  GeographicTilingScheme.prototype.getNumberOfXTilesAtLevel = function (level) {
    return this._numberOfLevelZeroTilesX << level;
  };

  /**
   * Gets the total number of tiles in the Y direction at a specified level-of-detail.
   *
   * @param {Number} level The level-of-detail.
   * @returns {Number} The number of tiles in the Y direction at the given level.
   */
  GeographicTilingScheme.prototype.getNumberOfYTilesAtLevel = function (level) {
    return this._numberOfLevelZeroTilesY << level;
  };

  /**
   * Transforms a rectangle specified in geodetic radians to the native coordinate system
   * of this tiling scheme.
   *
   * @param {Rectangle} rectangle The rectangle to transform.
   * @param {Rectangle} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the native rectangle if 'result'
   *          is undefined.
   */
  GeographicTilingScheme.prototype.rectangleToNativeRectangle = function (
    rectangle,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("rectangle", rectangle);
    //>>includeEnd('debug');

    var west = CesiumMath.toDegrees(rectangle.west);
    var south = CesiumMath.toDegrees(rectangle.south);
    var east = CesiumMath.toDegrees(rectangle.east);
    var north = CesiumMath.toDegrees(rectangle.north);

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Converts tile x, y coordinates and level to a rectangle expressed in the native coordinates
   * of the tiling scheme.
   *
   * @param {Number} x The integer x coordinate of the tile.
   * @param {Number} y The integer y coordinate of the tile.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Object} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the rectangle
   *          if 'result' is undefined.
   */
  GeographicTilingScheme.prototype.tileXYToNativeRectangle = function (
    x,
    y,
    level,
    result
  ) {
    var rectangleRadians = this.tileXYToRectangle(x, y, level, result);
    rectangleRadians.west = CesiumMath.toDegrees(rectangleRadians.west);
    rectangleRadians.south = CesiumMath.toDegrees(rectangleRadians.south);
    rectangleRadians.east = CesiumMath.toDegrees(rectangleRadians.east);
    rectangleRadians.north = CesiumMath.toDegrees(rectangleRadians.north);
    return rectangleRadians;
  };

  /**
   * Converts tile x, y coordinates and level to a cartographic rectangle in radians.
   *
   * @param {Number} x The integer x coordinate of the tile.
   * @param {Number} y The integer y coordinate of the tile.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Object} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the rectangle
   *          if 'result' is undefined.
   */
  GeographicTilingScheme.prototype.tileXYToRectangle = function (
    x,
    y,
    level,
    result
  ) {
    var rectangle = this._rectangle;

    var xTiles = this.getNumberOfXTilesAtLevel(level);
    var yTiles = this.getNumberOfYTilesAtLevel(level);

    var xTileWidth = rectangle.width / xTiles;
    var west = x * xTileWidth + rectangle.west;
    var east = (x + 1) * xTileWidth + rectangle.west;

    var yTileHeight = rectangle.height / yTiles;
    var north = rectangle.north - y * yTileHeight;
    var south = rectangle.north - (y + 1) * yTileHeight;

    if (!defined(result)) {
      result = new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Calculates the tile x, y coordinates of the tile containing
   * a given cartographic position.
   *
   * @param {Cartographic} position The position.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Cartesian2} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Cartesian2} The specified 'result', or a new object containing the tile x, y coordinates
   *          if 'result' is undefined.
   */
  GeographicTilingScheme.prototype.positionToTileXY = function (
    position,
    level,
    result
  ) {
    var rectangle = this._rectangle;
    if (!Rectangle.contains(rectangle, position)) {
      // outside the bounds of the tiling scheme
      return undefined;
    }

    var xTiles = this.getNumberOfXTilesAtLevel(level);
    var yTiles = this.getNumberOfYTilesAtLevel(level);

    var xTileWidth = rectangle.width / xTiles;
    var yTileHeight = rectangle.height / yTiles;

    var longitude = position.longitude;
    if (rectangle.east < rectangle.west) {
      longitude += CesiumMath.TWO_PI;
    }

    var xTileCoordinate = ((longitude - rectangle.west) / xTileWidth) | 0;
    if (xTileCoordinate >= xTiles) {
      xTileCoordinate = xTiles - 1;
    }

    var yTileCoordinate =
      ((rectangle.north - position.latitude) / yTileHeight) | 0;
    if (yTileCoordinate >= yTiles) {
      yTileCoordinate = yTiles - 1;
    }

    if (!defined(result)) {
      return new Cartesian2(xTileCoordinate, yTileCoordinate);
    }

    result.x = xTileCoordinate;
    result.y = yTileCoordinate;
    return result;
  };

  var scratchDiagonalCartesianNE = new Cartesian3();
  var scratchDiagonalCartesianSW = new Cartesian3();
  var scratchDiagonalCartographic = new Cartographic();
  var scratchCenterCartesian = new Cartesian3();
  var scratchSurfaceCartesian = new Cartesian3();

  var scratchBoundingSphere = new BoundingSphere();
  var tilingScheme = new GeographicTilingScheme();
  var scratchCorners = [
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
  ];
  var scratchTileXY = new Cartesian2();

  /**
   * A collection of functions for approximating terrain height
   * @private
   */
  var ApproximateTerrainHeights = {};

  /**
   * Initializes the minimum and maximum terrain heights
   * @return {Promise<void>}
   */
  ApproximateTerrainHeights.initialize = function () {
    var initPromise = ApproximateTerrainHeights._initPromise;
    if (defined(initPromise)) {
      return initPromise;
    }

    initPromise = Resource.fetchJson(
      buildModuleUrl("Assets/approximateTerrainHeights.json")
    ).then(function (json) {
      ApproximateTerrainHeights._terrainHeights = json;
    });
    ApproximateTerrainHeights._initPromise = initPromise;

    return initPromise;
  };

  /**
   * Computes the minimum and maximum terrain heights for a given rectangle
   * @param {Rectangle} rectangle The bounding rectangle
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid
   * @return {{minimumTerrainHeight: Number, maximumTerrainHeight: Number}}
   */
  ApproximateTerrainHeights.getMinimumMaximumHeights = function (
    rectangle,
    ellipsoid
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("rectangle", rectangle);
    if (!defined(ApproximateTerrainHeights._terrainHeights)) {
      throw new DeveloperError(
        "You must call ApproximateTerrainHeights.initialize and wait for the promise to resolve before using this function"
      );
    }
    //>>includeEnd('debug');
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var xyLevel = getTileXYLevel(rectangle);

    // Get the terrain min/max for that tile
    var minTerrainHeight = ApproximateTerrainHeights._defaultMinTerrainHeight;
    var maxTerrainHeight = ApproximateTerrainHeights._defaultMaxTerrainHeight;
    if (defined(xyLevel)) {
      var key = xyLevel.level + "-" + xyLevel.x + "-" + xyLevel.y;
      var heights = ApproximateTerrainHeights._terrainHeights[key];
      if (defined(heights)) {
        minTerrainHeight = heights[0];
        maxTerrainHeight = heights[1];
      }

      // Compute min by taking the center of the NE->SW diagonal and finding distance to the surface
      ellipsoid.cartographicToCartesian(
        Rectangle.northeast(rectangle, scratchDiagonalCartographic),
        scratchDiagonalCartesianNE
      );
      ellipsoid.cartographicToCartesian(
        Rectangle.southwest(rectangle, scratchDiagonalCartographic),
        scratchDiagonalCartesianSW
      );

      Cartesian3.midpoint(
        scratchDiagonalCartesianSW,
        scratchDiagonalCartesianNE,
        scratchCenterCartesian
      );
      var surfacePosition = ellipsoid.scaleToGeodeticSurface(
        scratchCenterCartesian,
        scratchSurfaceCartesian
      );
      if (defined(surfacePosition)) {
        var distance = Cartesian3.distance(
          scratchCenterCartesian,
          surfacePosition
        );
        minTerrainHeight = Math.min(minTerrainHeight, -distance);
      } else {
        minTerrainHeight = ApproximateTerrainHeights._defaultMinTerrainHeight;
      }
    }

    minTerrainHeight = Math.max(
      ApproximateTerrainHeights._defaultMinTerrainHeight,
      minTerrainHeight
    );

    return {
      minimumTerrainHeight: minTerrainHeight,
      maximumTerrainHeight: maxTerrainHeight,
    };
  };

  /**
   * Computes the bounding sphere based on the tile heights in the rectangle
   * @param {Rectangle} rectangle The bounding rectangle
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid
   * @return {BoundingSphere} The result bounding sphere
   */
  ApproximateTerrainHeights.getBoundingSphere = function (rectangle, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("rectangle", rectangle);
    if (!defined(ApproximateTerrainHeights._terrainHeights)) {
      throw new DeveloperError(
        "You must call ApproximateTerrainHeights.initialize and wait for the promise to resolve before using this function"
      );
    }
    //>>includeEnd('debug');
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var xyLevel = getTileXYLevel(rectangle);

    // Get the terrain max for that tile
    var maxTerrainHeight = ApproximateTerrainHeights._defaultMaxTerrainHeight;
    if (defined(xyLevel)) {
      var key = xyLevel.level + "-" + xyLevel.x + "-" + xyLevel.y;
      var heights = ApproximateTerrainHeights._terrainHeights[key];
      if (defined(heights)) {
        maxTerrainHeight = heights[1];
      }
    }

    var result = BoundingSphere.fromRectangle3D(rectangle, ellipsoid, 0.0);
    BoundingSphere.fromRectangle3D(
      rectangle,
      ellipsoid,
      maxTerrainHeight,
      scratchBoundingSphere
    );

    return BoundingSphere.union(result, scratchBoundingSphere, result);
  };

  function getTileXYLevel(rectangle) {
    Cartographic.fromRadians(
      rectangle.east,
      rectangle.north,
      0.0,
      scratchCorners[0]
    );
    Cartographic.fromRadians(
      rectangle.west,
      rectangle.north,
      0.0,
      scratchCorners[1]
    );
    Cartographic.fromRadians(
      rectangle.east,
      rectangle.south,
      0.0,
      scratchCorners[2]
    );
    Cartographic.fromRadians(
      rectangle.west,
      rectangle.south,
      0.0,
      scratchCorners[3]
    );

    // Determine which tile the bounding rectangle is in
    var lastLevelX = 0,
      lastLevelY = 0;
    var currentX = 0,
      currentY = 0;
    var maxLevel = ApproximateTerrainHeights._terrainHeightsMaxLevel;
    var i;
    for (i = 0; i <= maxLevel; ++i) {
      var failed = false;
      for (var j = 0; j < 4; ++j) {
        var corner = scratchCorners[j];
        tilingScheme.positionToTileXY(corner, i, scratchTileXY);
        if (j === 0) {
          currentX = scratchTileXY.x;
          currentY = scratchTileXY.y;
        } else if (currentX !== scratchTileXY.x || currentY !== scratchTileXY.y) {
          failed = true;
          break;
        }
      }

      if (failed) {
        break;
      }

      lastLevelX = currentX;
      lastLevelY = currentY;
    }

    if (i === 0) {
      return undefined;
    }

    return {
      x: lastLevelX,
      y: lastLevelY,
      level: i > maxLevel ? maxLevel : i - 1,
    };
  }

  ApproximateTerrainHeights._terrainHeightsMaxLevel = 6;
  ApproximateTerrainHeights._defaultMaxTerrainHeight = 9000.0;
  ApproximateTerrainHeights._defaultMinTerrainHeight = -100000.0;
  ApproximateTerrainHeights._terrainHeights = undefined;
  ApproximateTerrainHeights._initPromise = undefined;

  Object.defineProperties(ApproximateTerrainHeights, {
    /**
     * Determines if the terrain heights are initialized and ready to use. To initialize the terrain heights,
     * call {@link ApproximateTerrainHeights#initialize} and wait for the returned promise to resolve.
     * @type {Boolean}
     * @readonly
     * @memberof ApproximateTerrainHeights
     */
    initialized: {
      get: function () {
        return defined(ApproximateTerrainHeights._terrainHeights);
      },
    },
  });

  var html = ['a', 'abbr', 'acronym', 'address', 'area', 'article', 'aside', 'audio', 'b', 'bdi', 'bdo', 'big', 'blink', 'blockquote', 'body', 'br', 'button', 'canvas', 'caption', 'center', 'cite', 'code', 'col', 'colgroup', 'content', 'data', 'datalist', 'dd', 'decorator', 'del', 'details', 'dfn', 'dir', 'div', 'dl', 'dt', 'element', 'em', 'fieldset', 'figcaption', 'figure', 'font', 'footer', 'form', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'head', 'header', 'hgroup', 'hr', 'html', 'i', 'img', 'input', 'ins', 'kbd', 'label', 'legend', 'li', 'main', 'map', 'mark', 'marquee', 'menu', 'menuitem', 'meter', 'nav', 'nobr', 'ol', 'optgroup', 'option', 'output', 'p', 'pre', 'progress', 'q', 'rp', 'rt', 'ruby', 's', 'samp', 'section', 'select', 'shadow', 'small', 'source', 'spacer', 'span', 'strike', 'strong', 'style', 'sub', 'summary', 'sup', 'table', 'tbody', 'td', 'template', 'textarea', 'tfoot', 'th', 'thead', 'time', 'tr', 'track', 'tt', 'u', 'ul', 'var', 'video', 'wbr'];

  // SVG
  var svg = ['svg', 'a', 'altglyph', 'altglyphdef', 'altglyphitem', 'animatecolor', 'animatemotion', 'animatetransform', 'audio', 'canvas', 'circle', 'clippath', 'defs', 'desc', 'ellipse', 'filter', 'font', 'g', 'glyph', 'glyphref', 'hkern', 'image', 'line', 'lineargradient', 'marker', 'mask', 'metadata', 'mpath', 'path', 'pattern', 'polygon', 'polyline', 'radialgradient', 'rect', 'stop', 'style', 'switch', 'symbol', 'text', 'textpath', 'title', 'tref', 'tspan', 'video', 'view', 'vkern'];

  var svgFilters = ['feBlend', 'feColorMatrix', 'feComponentTransfer', 'feComposite', 'feConvolveMatrix', 'feDiffuseLighting', 'feDisplacementMap', 'feDistantLight', 'feFlood', 'feFuncA', 'feFuncB', 'feFuncG', 'feFuncR', 'feGaussianBlur', 'feMerge', 'feMergeNode', 'feMorphology', 'feOffset', 'fePointLight', 'feSpecularLighting', 'feSpotLight', 'feTile', 'feTurbulence'];

  var mathMl = ['math', 'menclose', 'merror', 'mfenced', 'mfrac', 'mglyph', 'mi', 'mlabeledtr', 'mmuliscripts', 'mn', 'mo', 'mover', 'mpadded', 'mphantom', 'mroot', 'mrow', 'ms', 'mpspace', 'msqrt', 'mystyle', 'msub', 'msup', 'msubsup', 'mtable', 'mtd', 'mtext', 'mtr', 'munder', 'munderover'];

  var text = ['#text'];

  var html$1 = ['accept', 'action', 'align', 'alt', 'autocomplete', 'background', 'bgcolor', 'border', 'cellpadding', 'cellspacing', 'checked', 'cite', 'class', 'clear', 'color', 'cols', 'colspan', 'coords', 'crossorigin', 'datetime', 'default', 'dir', 'disabled', 'download', 'enctype', 'face', 'for', 'headers', 'height', 'hidden', 'high', 'href', 'hreflang', 'id', 'integrity', 'ismap', 'label', 'lang', 'list', 'loop', 'low', 'max', 'maxlength', 'media', 'method', 'min', 'multiple', 'name', 'noshade', 'novalidate', 'nowrap', 'open', 'optimum', 'pattern', 'placeholder', 'poster', 'preload', 'pubdate', 'radiogroup', 'readonly', 'rel', 'required', 'rev', 'reversed', 'role', 'rows', 'rowspan', 'spellcheck', 'scope', 'selected', 'shape', 'size', 'sizes', 'span', 'srclang', 'start', 'src', 'srcset', 'step', 'style', 'summary', 'tabindex', 'title', 'type', 'usemap', 'valign', 'value', 'width', 'xmlns'];

  var svg$1 = ['accent-height', 'accumulate', 'additivive', 'alignment-baseline', 'ascent', 'attributename', 'attributetype', 'azimuth', 'basefrequency', 'baseline-shift', 'begin', 'bias', 'by', 'class', 'clip', 'clip-path', 'clip-rule', 'color', 'color-interpolation', 'color-interpolation-filters', 'color-profile', 'color-rendering', 'cx', 'cy', 'd', 'dx', 'dy', 'diffuseconstant', 'direction', 'display', 'divisor', 'dur', 'edgemode', 'elevation', 'end', 'fill', 'fill-opacity', 'fill-rule', 'filter', 'flood-color', 'flood-opacity', 'font-family', 'font-size', 'font-size-adjust', 'font-stretch', 'font-style', 'font-variant', 'font-weight', 'fx', 'fy', 'g1', 'g2', 'glyph-name', 'glyphref', 'gradientunits', 'gradienttransform', 'height', 'href', 'id', 'image-rendering', 'in', 'in2', 'k', 'k1', 'k2', 'k3', 'k4', 'kerning', 'keypoints', 'keysplines', 'keytimes', 'lang', 'lengthadjust', 'letter-spacing', 'kernelmatrix', 'kernelunitlength', 'lighting-color', 'local', 'marker-end', 'marker-mid', 'marker-start', 'markerheight', 'markerunits', 'markerwidth', 'maskcontentunits', 'maskunits', 'max', 'mask', 'media', 'method', 'mode', 'min', 'name', 'numoctaves', 'offset', 'operator', 'opacity', 'order', 'orient', 'orientation', 'origin', 'overflow', 'paint-order', 'path', 'pathlength', 'patterncontentunits', 'patterntransform', 'patternunits', 'points', 'preservealpha', 'preserveaspectratio', 'r', 'rx', 'ry', 'radius', 'refx', 'refy', 'repeatcount', 'repeatdur', 'restart', 'result', 'rotate', 'scale', 'seed', 'shape-rendering', 'specularconstant', 'specularexponent', 'spreadmethod', 'stddeviation', 'stitchtiles', 'stop-color', 'stop-opacity', 'stroke-dasharray', 'stroke-dashoffset', 'stroke-linecap', 'stroke-linejoin', 'stroke-miterlimit', 'stroke-opacity', 'stroke', 'stroke-width', 'style', 'surfacescale', 'tabindex', 'targetx', 'targety', 'transform', 'text-anchor', 'text-decoration', 'text-rendering', 'textlength', 'type', 'u1', 'u2', 'unicode', 'values', 'viewbox', 'visibility', 'vert-adv-y', 'vert-origin-x', 'vert-origin-y', 'width', 'word-spacing', 'wrap', 'writing-mode', 'xchannelselector', 'ychannelselector', 'x', 'x1', 'x2', 'xmlns', 'y', 'y1', 'y2', 'z', 'zoomandpan'];

  var mathMl$1 = ['accent', 'accentunder', 'align', 'bevelled', 'close', 'columnsalign', 'columnlines', 'columnspan', 'denomalign', 'depth', 'dir', 'display', 'displaystyle', 'fence', 'frame', 'height', 'href', 'id', 'largeop', 'length', 'linethickness', 'lspace', 'lquote', 'mathbackground', 'mathcolor', 'mathsize', 'mathvariant', 'maxsize', 'minsize', 'movablelimits', 'notation', 'numalign', 'open', 'rowalign', 'rowlines', 'rowspacing', 'rowspan', 'rspace', 'rquote', 'scriptlevel', 'scriptminsize', 'scriptsizemultiplier', 'selection', 'separator', 'separators', 'stretchy', 'subscriptshift', 'supscriptshift', 'symmetric', 'voffset', 'width', 'xmlns'];

  var xml = ['xlink:href', 'xml:id', 'xlink:title', 'xml:space', 'xmlns:xlink'];

  /* Add properties to a lookup table */
  function addToSet(set, array) {
    var l = array.length;
    while (l--) {
      if (typeof array[l] === 'string') {
        array[l] = array[l].toLowerCase();
      }
      set[array[l]] = true;
    }
    return set;
  }

  /* Shallow clone an object */
  function clone$1(object) {
    var newObject = {};
    var property = void 0;
    for (property in object) {
      if (Object.prototype.hasOwnProperty.call(object, property)) {
        newObject[property] = object[property];
      }
    }
    return newObject;
  }

  var MUSTACHE_EXPR = /\{\{[\s\S]*|[\s\S]*\}\}/gm; // Specify template detection regex for SAFE_FOR_TEMPLATES mode
  var ERB_EXPR = /<%[\s\S]*|[\s\S]*%>/gm;
  var DATA_ATTR = /^data-[\-\w.\u00B7-\uFFFF]/; // eslint-disable-line no-useless-escape
  var ARIA_ATTR = /^aria-[\-\w]+$/; // eslint-disable-line no-useless-escape
  var IS_ALLOWED_URI = /^(?:(?:(?:f|ht)tps?|mailto|tel|callto|cid|xmpp):|[^a-z]|[a-z+.\-]+(?:[^a-z+.\-:]|$))/i; // eslint-disable-line no-useless-escape
  var IS_SCRIPT_OR_DATA = /^(?:\w+script|data):/i;
  var ATTR_WHITESPACE = /[\u0000-\u0020\u00A0\u1680\u180E\u2000-\u2029\u205f\u3000]/g; // eslint-disable-line no-control-regex

  var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };

  function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }

  var getGlobal = function getGlobal() {
    return typeof window === 'undefined' ? null : window;
  };

  function createDOMPurify() {
    var window = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : getGlobal();

    var DOMPurify = function DOMPurify(root) {
      return createDOMPurify(root);
    };

    /**
     * Version label, exposed for easier checks
     * if DOMPurify is up to date or not
     */
    DOMPurify.version = '1.0.8';

    /**
     * Array of elements that DOMPurify removed during sanitation.
     * Empty if nothing was removed.
     */
    DOMPurify.removed = [];

    if (!window || !window.document || window.document.nodeType !== 9) {
      // Not running in a browser, provide a factory function
      // so that you can pass your own Window
      DOMPurify.isSupported = false;

      return DOMPurify;
    }

    var originalDocument = window.document;
    var useDOMParser = false; // See comment below
    var removeTitle = false; // See comment below

    var document = window.document;
    var DocumentFragment = window.DocumentFragment,
        HTMLTemplateElement = window.HTMLTemplateElement,
        Node = window.Node,
        NodeFilter = window.NodeFilter,
        _window$NamedNodeMap = window.NamedNodeMap,
        NamedNodeMap = _window$NamedNodeMap === undefined ? window.NamedNodeMap || window.MozNamedAttrMap : _window$NamedNodeMap,
        Text = window.Text,
        Comment = window.Comment,
        DOMParser = window.DOMParser;

    // As per issue #47, the web-components registry is inherited by a
    // new document created via createHTMLDocument. As per the spec
    // (http://w3c.github.io/webcomponents/spec/custom/#creating-and-passing-registries)
    // a new empty registry is used when creating a template contents owner
    // document, so we use that as our parent document to ensure nothing
    // is inherited.

    if (typeof HTMLTemplateElement === 'function') {
      var template = document.createElement('template');
      if (template.content && template.content.ownerDocument) {
        document = template.content.ownerDocument;
      }
    }

    var _document = document,
        implementation = _document.implementation,
        createNodeIterator = _document.createNodeIterator,
        getElementsByTagName = _document.getElementsByTagName,
        createDocumentFragment = _document.createDocumentFragment;
    var importNode = originalDocument.importNode;


    var hooks = {};

    /**
     * Expose whether this browser supports running the full DOMPurify.
     */
    DOMPurify.isSupported = implementation && typeof implementation.createHTMLDocument !== 'undefined' && document.documentMode !== 9;

    var MUSTACHE_EXPR$$1 = MUSTACHE_EXPR,
        ERB_EXPR$$1 = ERB_EXPR,
        DATA_ATTR$$1 = DATA_ATTR,
        ARIA_ATTR$$1 = ARIA_ATTR,
        IS_SCRIPT_OR_DATA$$1 = IS_SCRIPT_OR_DATA,
        ATTR_WHITESPACE$$1 = ATTR_WHITESPACE;
    var IS_ALLOWED_URI$$1 = IS_ALLOWED_URI;
    /**
     * We consider the elements and attributes below to be safe. Ideally
     * don't add any new ones but feel free to remove unwanted ones.
     */

    /* allowed element names */

    var ALLOWED_TAGS = null;
    var DEFAULT_ALLOWED_TAGS = addToSet({}, [].concat(_toConsumableArray(html), _toConsumableArray(svg), _toConsumableArray(svgFilters), _toConsumableArray(mathMl), _toConsumableArray(text)));

    /* Allowed attribute names */
    var ALLOWED_ATTR = null;
    var DEFAULT_ALLOWED_ATTR = addToSet({}, [].concat(_toConsumableArray(html$1), _toConsumableArray(svg$1), _toConsumableArray(mathMl$1), _toConsumableArray(xml)));

    /* Explicitly forbidden tags (overrides ALLOWED_TAGS/ADD_TAGS) */
    var FORBID_TAGS = null;

    /* Explicitly forbidden attributes (overrides ALLOWED_ATTR/ADD_ATTR) */
    var FORBID_ATTR = null;

    /* Decide if ARIA attributes are okay */
    var ALLOW_ARIA_ATTR = true;

    /* Decide if custom data attributes are okay */
    var ALLOW_DATA_ATTR = true;

    /* Decide if unknown protocols are okay */
    var ALLOW_UNKNOWN_PROTOCOLS = false;

    /* Output should be safe for jQuery's $() factory? */
    var SAFE_FOR_JQUERY = false;

    /* Output should be safe for common template engines.
     * This means, DOMPurify removes data attributes, mustaches and ERB
     */
    var SAFE_FOR_TEMPLATES = false;

    /* Decide if document with <html>... should be returned */
    var WHOLE_DOCUMENT = false;

    /* Track whether config is already set on this instance of DOMPurify. */
    var SET_CONFIG = false;

    /* Decide if all elements (e.g. style, script) must be children of
     * document.body. By default, browsers might move them to document.head */
    var FORCE_BODY = false;

    /* Decide if a DOM `HTMLBodyElement` should be returned, instead of a html string.
     * If `WHOLE_DOCUMENT` is enabled a `HTMLHtmlElement` will be returned instead
     */
    var RETURN_DOM = false;

    /* Decide if a DOM `DocumentFragment` should be returned, instead of a html string */
    var RETURN_DOM_FRAGMENT = false;

    /* If `RETURN_DOM` or `RETURN_DOM_FRAGMENT` is enabled, decide if the returned DOM
     * `Node` is imported into the current `Document`. If this flag is not enabled the
     * `Node` will belong (its ownerDocument) to a fresh `HTMLDocument`, created by
     * DOMPurify. */
    var RETURN_DOM_IMPORT = false;

    /* Output should be free from DOM clobbering attacks? */
    var SANITIZE_DOM = true;

    /* Keep element content when removing element? */
    var KEEP_CONTENT = true;

    /* If a `Node` is passed to sanitize(), then performs sanitization in-place instead
     * of importing it into a new Document and returning a sanitized copy */
    var IN_PLACE = false;

    /* Allow usage of profiles like html, svg and mathMl */
    var USE_PROFILES = {};

    /* Tags to ignore content of when KEEP_CONTENT is true */
    var FORBID_CONTENTS = addToSet({}, ['audio', 'head', 'math', 'script', 'style', 'template', 'svg', 'video']);

    /* Tags that are safe for data: URIs */
    var DATA_URI_TAGS = addToSet({}, ['audio', 'video', 'img', 'source', 'image']);

    /* Attributes safe for values like "javascript:" */
    var URI_SAFE_ATTRIBUTES = addToSet({}, ['alt', 'class', 'for', 'id', 'label', 'name', 'pattern', 'placeholder', 'summary', 'title', 'value', 'style', 'xmlns']);

    /* Keep a reference to config to pass to hooks */
    var CONFIG = null;

    /* Ideally, do not touch anything below this line */
    /* ______________________________________________ */

    var formElement = document.createElement('form');

    /**
     * _parseConfig
     *
     * @param  {Object} cfg optional config literal
     */
    // eslint-disable-next-line complexity
    var _parseConfig = function _parseConfig(cfg) {
      /* Shield configuration object from tampering */
      if ((typeof cfg === 'undefined' ? 'undefined' : _typeof(cfg)) !== 'object') {
        cfg = {};
      }
      /* Set configuration parameters */
      ALLOWED_TAGS = 'ALLOWED_TAGS' in cfg ? addToSet({}, cfg.ALLOWED_TAGS) : DEFAULT_ALLOWED_TAGS;
      ALLOWED_ATTR = 'ALLOWED_ATTR' in cfg ? addToSet({}, cfg.ALLOWED_ATTR) : DEFAULT_ALLOWED_ATTR;
      FORBID_TAGS = 'FORBID_TAGS' in cfg ? addToSet({}, cfg.FORBID_TAGS) : {};
      FORBID_ATTR = 'FORBID_ATTR' in cfg ? addToSet({}, cfg.FORBID_ATTR) : {};
      USE_PROFILES = 'USE_PROFILES' in cfg ? cfg.USE_PROFILES : false;
      ALLOW_ARIA_ATTR = cfg.ALLOW_ARIA_ATTR !== false; // Default true
      ALLOW_DATA_ATTR = cfg.ALLOW_DATA_ATTR !== false; // Default true
      ALLOW_UNKNOWN_PROTOCOLS = cfg.ALLOW_UNKNOWN_PROTOCOLS || false; // Default false
      SAFE_FOR_JQUERY = cfg.SAFE_FOR_JQUERY || false; // Default false
      SAFE_FOR_TEMPLATES = cfg.SAFE_FOR_TEMPLATES || false; // Default false
      WHOLE_DOCUMENT = cfg.WHOLE_DOCUMENT || false; // Default false
      RETURN_DOM = cfg.RETURN_DOM || false; // Default false
      RETURN_DOM_FRAGMENT = cfg.RETURN_DOM_FRAGMENT || false; // Default false
      RETURN_DOM_IMPORT = cfg.RETURN_DOM_IMPORT || false; // Default false
      FORCE_BODY = cfg.FORCE_BODY || false; // Default false
      SANITIZE_DOM = cfg.SANITIZE_DOM !== false; // Default true
      KEEP_CONTENT = cfg.KEEP_CONTENT !== false; // Default true
      IN_PLACE = cfg.IN_PLACE || false; // Default false

      IS_ALLOWED_URI$$1 = cfg.ALLOWED_URI_REGEXP || IS_ALLOWED_URI$$1;

      if (SAFE_FOR_TEMPLATES) {
        ALLOW_DATA_ATTR = false;
      }

      if (RETURN_DOM_FRAGMENT) {
        RETURN_DOM = true;
      }

      /* Parse profile info */
      if (USE_PROFILES) {
        ALLOWED_TAGS = addToSet({}, [].concat(_toConsumableArray(text)));
        ALLOWED_ATTR = [];
        if (USE_PROFILES.html === true) {
          addToSet(ALLOWED_TAGS, html);
          addToSet(ALLOWED_ATTR, html$1);
        }
        if (USE_PROFILES.svg === true) {
          addToSet(ALLOWED_TAGS, svg);
          addToSet(ALLOWED_ATTR, svg$1);
          addToSet(ALLOWED_ATTR, xml);
        }
        if (USE_PROFILES.svgFilters === true) {
          addToSet(ALLOWED_TAGS, svgFilters);
          addToSet(ALLOWED_ATTR, svg$1);
          addToSet(ALLOWED_ATTR, xml);
        }
        if (USE_PROFILES.mathMl === true) {
          addToSet(ALLOWED_TAGS, mathMl);
          addToSet(ALLOWED_ATTR, mathMl$1);
          addToSet(ALLOWED_ATTR, xml);
        }
      }

      /* Merge configuration parameters */
      if (cfg.ADD_TAGS) {
        if (ALLOWED_TAGS === DEFAULT_ALLOWED_TAGS) {
          ALLOWED_TAGS = clone$1(ALLOWED_TAGS);
        }
        addToSet(ALLOWED_TAGS, cfg.ADD_TAGS);
      }
      if (cfg.ADD_ATTR) {
        if (ALLOWED_ATTR === DEFAULT_ALLOWED_ATTR) {
          ALLOWED_ATTR = clone$1(ALLOWED_ATTR);
        }
        addToSet(ALLOWED_ATTR, cfg.ADD_ATTR);
      }
      if (cfg.ADD_URI_SAFE_ATTR) {
        addToSet(URI_SAFE_ATTRIBUTES, cfg.ADD_URI_SAFE_ATTR);
      }

      /* Add #text in case KEEP_CONTENT is set to true */
      if (KEEP_CONTENT) {
        ALLOWED_TAGS['#text'] = true;
      }

      /* Add html, head and body to ALLOWED_TAGS in case WHOLE_DOCUMENT is true */
      if (WHOLE_DOCUMENT) {
        addToSet(ALLOWED_TAGS, ['html', 'head', 'body']);
      }

      /* Add tbody to ALLOWED_TAGS in case tables are permitted, see #286 */
      if (ALLOWED_TAGS.table) {
        addToSet(ALLOWED_TAGS, ['tbody']);
      }

      // Prevent further manipulation of configuration.
      // Not available in IE8, Safari 5, etc.
      if (Object && 'freeze' in Object) {
        Object.freeze(cfg);
      }

      CONFIG = cfg;
    };

    /**
     * _forceRemove
     *
     * @param  {Node} node a DOM node
     */
    var _forceRemove = function _forceRemove(node) {
      DOMPurify.removed.push({ element: node });
      try {
        node.parentNode.removeChild(node);
      } catch (err) {
        node.outerHTML = '';
      }
    };

    /**
     * _removeAttribute
     *
     * @param  {String} name an Attribute name
     * @param  {Node} node a DOM node
     */
    var _removeAttribute = function _removeAttribute(name, node) {
      try {
        DOMPurify.removed.push({
          attribute: node.getAttributeNode(name),
          from: node
        });
      } catch (err) {
        DOMPurify.removed.push({
          attribute: null,
          from: node
        });
      }
      node.removeAttribute(name);
    };

    /**
     * _initDocument
     *
     * @param  {String} dirty a string of dirty markup
     * @return {Document} a DOM, filled with the dirty markup
     */
    var _initDocument = function _initDocument(dirty) {
      /* Create a HTML document */
      var doc = void 0;
      var leadingWhitespace = void 0;

      if (FORCE_BODY) {
        dirty = '<remove></remove>' + dirty;
      } else {
        /* If FORCE_BODY isn't used, leading whitespace needs to be preserved manually */
        var matches = dirty.match(/^[\s]+/);
        leadingWhitespace = matches && matches[0];
        if (leadingWhitespace) {
          dirty = dirty.slice(leadingWhitespace.length);
        }
      }

      /* Use DOMParser to workaround Firefox bug (see comment below) */
      if (useDOMParser) {
        try {
          doc = new DOMParser().parseFromString(dirty, 'text/html');
        } catch (err) {}
      }

      /* Remove title to fix an mXSS bug in older MS Edge */
      if (removeTitle) {
        addToSet(FORBID_TAGS, ['title']);
      }

      /* Otherwise use createHTMLDocument, because DOMParser is unsafe in
      Safari (see comment below) */
      if (!doc || !doc.documentElement) {
        doc = implementation.createHTMLDocument('');
        var _doc = doc,
            body = _doc.body;

        body.parentNode.removeChild(body.parentNode.firstElementChild);
        body.outerHTML = dirty;
      }

      if (leadingWhitespace) {
        doc.body.insertBefore(document.createTextNode(leadingWhitespace), doc.body.childNodes[0] || null);
      }

      /* Work on whole document or just its body */
      return getElementsByTagName.call(doc, WHOLE_DOCUMENT ? 'html' : 'body')[0];
    };

    // Firefox uses a different parser for innerHTML rather than
    // DOMParser (see https://bugzilla.mozilla.org/show_bug.cgi?id=1205631)
    // which means that you *must* use DOMParser, otherwise the output may
    // not be safe if used in a document.write context later.
    //
    // So we feature detect the Firefox bug and use the DOMParser if necessary.
    //
    // MS Edge, in older versions, is affected by an mXSS behavior. The second
    // check tests for the behavior and fixes it if necessary.
    if (DOMPurify.isSupported) {
      (function () {
        try {
          var doc = _initDocument('<svg><p><style><img src="</style><img src=x onerror=alert(1)//">');
          if (doc.querySelector('svg img')) {
            useDOMParser = true;
          }
        } catch (err) {}
      })();
      (function () {
        try {
          var doc = _initDocument('<x/><title>&lt;/title&gt;&lt;img&gt;');
          if (doc.querySelector('title').textContent.match(/<\/title/)) {
            removeTitle = true;
          }
        } catch (err) {}
      })();
    }

    /**
     * _createIterator
     *
     * @param  {Document} root document/fragment to create iterator for
     * @return {Iterator} iterator instance
     */
    var _createIterator = function _createIterator(root) {
      return createNodeIterator.call(root.ownerDocument || root, root, NodeFilter.SHOW_ELEMENT | NodeFilter.SHOW_COMMENT | NodeFilter.SHOW_TEXT, function () {
        return NodeFilter.FILTER_ACCEPT;
      }, false);
    };

    /**
     * _isClobbered
     *
     * @param  {Node} elm element to check for clobbering attacks
     * @return {Boolean} true if clobbered, false if safe
     */
    var _isClobbered = function _isClobbered(elm) {
      if (elm instanceof Text || elm instanceof Comment) {
        return false;
      }
      if (typeof elm.nodeName !== 'string' || typeof elm.textContent !== 'string' || typeof elm.removeChild !== 'function' || !(elm.attributes instanceof NamedNodeMap) || typeof elm.removeAttribute !== 'function' || typeof elm.setAttribute !== 'function') {
        return true;
      }
      return false;
    };

    /**
     * _isNode
     *
     * @param  {Node} obj object to check whether it's a DOM node
     * @return {Boolean} true is object is a DOM node
     */
    var _isNode = function _isNode(obj) {
      return (typeof Node === 'undefined' ? 'undefined' : _typeof(Node)) === 'object' ? obj instanceof Node : obj && (typeof obj === 'undefined' ? 'undefined' : _typeof(obj)) === 'object' && typeof obj.nodeType === 'number' && typeof obj.nodeName === 'string';
    };

    /**
     * _executeHook
     * Execute user configurable hooks
     *
     * @param  {String} entryPoint  Name of the hook's entry point
     * @param  {Node} currentNode node to work on with the hook
     * @param  {Object} data additional hook parameters
     */
    var _executeHook = function _executeHook(entryPoint, currentNode, data) {
      if (!hooks[entryPoint]) {
        return;
      }

      hooks[entryPoint].forEach(function (hook) {
        hook.call(DOMPurify, currentNode, data, CONFIG);
      });
    };

    /**
     * _sanitizeElements
     *
     * @protect nodeName
     * @protect textContent
     * @protect removeChild
     *
     * @param   {Node} currentNode to check for permission to exist
     * @return  {Boolean} true if node was killed, false if left alive
     */
    var _sanitizeElements = function _sanitizeElements(currentNode) {
      var content = void 0;

      /* Execute a hook if present */
      _executeHook('beforeSanitizeElements', currentNode, null);

      /* Check if element is clobbered or can clobber */
      if (_isClobbered(currentNode)) {
        _forceRemove(currentNode);
        return true;
      }

      /* Now let's check the element's type and name */
      var tagName = currentNode.nodeName.toLowerCase();

      /* Execute a hook if present */
      _executeHook('uponSanitizeElement', currentNode, {
        tagName: tagName,
        allowedTags: ALLOWED_TAGS
      });

      /* Remove element if anything forbids its presence */
      if (!ALLOWED_TAGS[tagName] || FORBID_TAGS[tagName]) {
        /* Keep content except for black-listed elements */
        if (KEEP_CONTENT && !FORBID_CONTENTS[tagName] && typeof currentNode.insertAdjacentHTML === 'function') {
          try {
            currentNode.insertAdjacentHTML('AfterEnd', currentNode.innerHTML);
          } catch (err) {}
        }
        _forceRemove(currentNode);
        return true;
      }

      /* Convert markup to cover jQuery behavior */
      if (SAFE_FOR_JQUERY && !currentNode.firstElementChild && (!currentNode.content || !currentNode.content.firstElementChild) && /</g.test(currentNode.textContent)) {
        DOMPurify.removed.push({ element: currentNode.cloneNode() });
        if (currentNode.innerHTML) {
          currentNode.innerHTML = currentNode.innerHTML.replace(/</g, '&lt;');
        } else {
          currentNode.innerHTML = currentNode.textContent.replace(/</g, '&lt;');
        }
      }

      /* Sanitize element content to be template-safe */
      if (SAFE_FOR_TEMPLATES && currentNode.nodeType === 3) {
        /* Get the element's text content */
        content = currentNode.textContent;
        content = content.replace(MUSTACHE_EXPR$$1, ' ');
        content = content.replace(ERB_EXPR$$1, ' ');
        if (currentNode.textContent !== content) {
          DOMPurify.removed.push({ element: currentNode.cloneNode() });
          currentNode.textContent = content;
        }
      }

      /* Execute a hook if present */
      _executeHook('afterSanitizeElements', currentNode, null);

      return false;
    };

    /**
     * _isValidAttribute
     *
     * @param  {string} lcTag Lowercase tag name of containing element.
     * @param  {string} lcName Lowercase attribute name.
     * @param  {string} value Attribute value.
     * @return {Boolean} Returns true if `value` is valid, otherwise false.
     */
    var _isValidAttribute = function _isValidAttribute(lcTag, lcName, value) {
      /* Make sure attribute cannot clobber */
      if (SANITIZE_DOM && (lcName === 'id' || lcName === 'name') && (value in document || value in formElement)) {
        return false;
      }

      /* Sanitize attribute content to be template-safe */
      if (SAFE_FOR_TEMPLATES) {
        value = value.replace(MUSTACHE_EXPR$$1, ' ');
        value = value.replace(ERB_EXPR$$1, ' ');
      }

      /* Allow valid data-* attributes: At least one character after "-"
          (https://html.spec.whatwg.org/multipage/dom.html#embedding-custom-non-visible-data-with-the-data-*-attributes)
          XML-compatible (https://html.spec.whatwg.org/multipage/infrastructure.html#xml-compatible and http://www.w3.org/TR/xml/#d0e804)
          We don't need to check the value; it's always URI safe. */
      if (ALLOW_DATA_ATTR && DATA_ATTR$$1.test(lcName)) ; else if (ALLOW_ARIA_ATTR && ARIA_ATTR$$1.test(lcName)) ; else if (!ALLOWED_ATTR[lcName] || FORBID_ATTR[lcName]) {
        return false;

        /* Check value is safe. First, is attr inert? If so, is safe */
      } else if (URI_SAFE_ATTRIBUTES[lcName]) ; else if (IS_ALLOWED_URI$$1.test(value.replace(ATTR_WHITESPACE$$1, ''))) ; else if ((lcName === 'src' || lcName === 'xlink:href') && lcTag !== 'script' && value.indexOf('data:') === 0 && DATA_URI_TAGS[lcTag]) ; else if (ALLOW_UNKNOWN_PROTOCOLS && !IS_SCRIPT_OR_DATA$$1.test(value.replace(ATTR_WHITESPACE$$1, ''))) ; else if (!value) ; else {
        return false;
      }
      return true;
    };

    /**
     * _sanitizeAttributes
     *
     * @protect attributes
     * @protect nodeName
     * @protect removeAttribute
     * @protect setAttribute
     *
     * @param  {Node} node to sanitize
     */
    // eslint-disable-next-line complexity
    var _sanitizeAttributes = function _sanitizeAttributes(currentNode) {
      var attr = void 0;
      var value = void 0;
      var lcName = void 0;
      var idAttr = void 0;
      var l = void 0;
      /* Execute a hook if present */
      _executeHook('beforeSanitizeAttributes', currentNode, null);

      var attributes = currentNode.attributes;

      /* Check if we have attributes; if not we might have a text node */

      if (!attributes) {
        return;
      }

      var hookEvent = {
        attrName: '',
        attrValue: '',
        keepAttr: true,
        allowedAttributes: ALLOWED_ATTR
      };
      l = attributes.length;

      /* Go backwards over all attributes; safely remove bad ones */
      while (l--) {
        attr = attributes[l];
        var _attr = attr,
            name = _attr.name,
            namespaceURI = _attr.namespaceURI;

        value = attr.value.trim();
        lcName = name.toLowerCase();

        /* Execute a hook if present */
        hookEvent.attrName = lcName;
        hookEvent.attrValue = value;
        hookEvent.keepAttr = true;
        _executeHook('uponSanitizeAttribute', currentNode, hookEvent);
        value = hookEvent.attrValue;

        /* Remove attribute */
        // Safari (iOS + Mac), last tested v8.0.5, crashes if you try to
        // remove a "name" attribute from an <img> tag that has an "id"
        // attribute at the time.
        if (lcName === 'name' && currentNode.nodeName === 'IMG' && attributes.id) {
          idAttr = attributes.id;
          attributes = Array.prototype.slice.apply(attributes);
          _removeAttribute('id', currentNode);
          _removeAttribute(name, currentNode);
          if (attributes.indexOf(idAttr) > l) {
            currentNode.setAttribute('id', idAttr.value);
          }
        } else if (
        // This works around a bug in Safari, where input[type=file]
        // cannot be dynamically set after type has been removed
        currentNode.nodeName === 'INPUT' && lcName === 'type' && value === 'file' && (ALLOWED_ATTR[lcName] || !FORBID_ATTR[lcName])) {
          continue;
        } else {
          // This avoids a crash in Safari v9.0 with double-ids.
          // The trick is to first set the id to be empty and then to
          // remove the attribute
          if (name === 'id') {
            currentNode.setAttribute(name, '');
          }
          _removeAttribute(name, currentNode);
        }

        /* Did the hooks approve of the attribute? */
        if (!hookEvent.keepAttr) {
          continue;
        }

        /* Is `value` valid for this attribute? */
        var lcTag = currentNode.nodeName.toLowerCase();
        if (!_isValidAttribute(lcTag, lcName, value)) {
          continue;
        }

        /* Handle invalid data-* attribute set by try-catching it */
        try {
          if (namespaceURI) {
            currentNode.setAttributeNS(namespaceURI, name, value);
          } else {
            /* Fallback to setAttribute() for browser-unrecognized namespaces e.g. "x-schema". */
            currentNode.setAttribute(name, value);
          }
          DOMPurify.removed.pop();
        } catch (err) {}
      }

      /* Execute a hook if present */
      _executeHook('afterSanitizeAttributes', currentNode, null);
    };

    /**
     * _sanitizeShadowDOM
     *
     * @param  {DocumentFragment} fragment to iterate over recursively
     */
    var _sanitizeShadowDOM = function _sanitizeShadowDOM(fragment) {
      var shadowNode = void 0;
      var shadowIterator = _createIterator(fragment);

      /* Execute a hook if present */
      _executeHook('beforeSanitizeShadowDOM', fragment, null);

      while (shadowNode = shadowIterator.nextNode()) {
        /* Execute a hook if present */
        _executeHook('uponSanitizeShadowNode', shadowNode, null);

        /* Sanitize tags and elements */
        if (_sanitizeElements(shadowNode)) {
          continue;
        }

        /* Deep shadow DOM detected */
        if (shadowNode.content instanceof DocumentFragment) {
          _sanitizeShadowDOM(shadowNode.content);
        }

        /* Check attributes, sanitize if necessary */
        _sanitizeAttributes(shadowNode);
      }

      /* Execute a hook if present */
      _executeHook('afterSanitizeShadowDOM', fragment, null);
    };

    /**
     * Sanitize
     * Public method providing core sanitation functionality
     *
     * @param {String|Node} dirty string or DOM node
     * @param {Object} configuration object
     */
    // eslint-disable-next-line complexity
    DOMPurify.sanitize = function (dirty, cfg) {
      var body = void 0;
      var importedNode = void 0;
      var currentNode = void 0;
      var oldNode = void 0;
      var returnNode = void 0;
      /* Make sure we have a string to sanitize.
        DO NOT return early, as this will return the wrong type if
        the user has requested a DOM object rather than a string */
      if (!dirty) {
        dirty = '<!-->';
      }

      /* Stringify, in case dirty is an object */
      if (typeof dirty !== 'string' && !_isNode(dirty)) {
        // eslint-disable-next-line no-negated-condition
        if (typeof dirty.toString !== 'function') {
          throw new TypeError('toString is not a function');
        } else {
          dirty = dirty.toString();
          if (typeof dirty !== 'string') {
            throw new TypeError('dirty is not a string, aborting');
          }
        }
      }

      /* Check we can run. Otherwise fall back or ignore */
      if (!DOMPurify.isSupported) {
        if (_typeof(window.toStaticHTML) === 'object' || typeof window.toStaticHTML === 'function') {
          if (typeof dirty === 'string') {
            return window.toStaticHTML(dirty);
          }
          if (_isNode(dirty)) {
            return window.toStaticHTML(dirty.outerHTML);
          }
        }
        return dirty;
      }

      /* Assign config vars */
      if (!SET_CONFIG) {
        _parseConfig(cfg);
      }

      /* Clean up removed elements */
      DOMPurify.removed = [];

      if (IN_PLACE) ; else if (dirty instanceof Node) {
        /* If dirty is a DOM element, append to an empty document to avoid
           elements being stripped by the parser */
        body = _initDocument('<!-->');
        importedNode = body.ownerDocument.importNode(dirty, true);
        if (importedNode.nodeType === 1 && importedNode.nodeName === 'BODY') {
          /* Node is already a body, use as is */
          body = importedNode;
        } else {
          body.appendChild(importedNode);
        }
      } else {
        /* Exit directly if we have nothing to do */
        if (!RETURN_DOM && !WHOLE_DOCUMENT && dirty.indexOf('<') === -1) {
          return dirty;
        }

        /* Initialize the document to work on */
        body = _initDocument(dirty);

        /* Check we have a DOM node from the data */
        if (!body) {
          return RETURN_DOM ? null : '';
        }
      }

      /* Remove first element node (ours) if FORCE_BODY is set */
      if (body && FORCE_BODY) {
        _forceRemove(body.firstChild);
      }

      /* Get node iterator */
      var nodeIterator = _createIterator(IN_PLACE ? dirty : body);

      /* Now start iterating over the created document */
      while (currentNode = nodeIterator.nextNode()) {
        /* Fix IE's strange behavior with manipulated textNodes #89 */
        if (currentNode.nodeType === 3 && currentNode === oldNode) {
          continue;
        }

        /* Sanitize tags and elements */
        if (_sanitizeElements(currentNode)) {
          continue;
        }

        /* Shadow DOM detected, sanitize it */
        if (currentNode.content instanceof DocumentFragment) {
          _sanitizeShadowDOM(currentNode.content);
        }

        /* Check attributes, sanitize if necessary */
        _sanitizeAttributes(currentNode);

        oldNode = currentNode;
      }

      /* If we sanitized `dirty` in-place, return it. */
      if (IN_PLACE) {
        return dirty;
      }

      /* Return sanitized string or DOM */
      if (RETURN_DOM) {
        if (RETURN_DOM_FRAGMENT) {
          returnNode = createDocumentFragment.call(body.ownerDocument);

          while (body.firstChild) {
            returnNode.appendChild(body.firstChild);
          }
        } else {
          returnNode = body;
        }

        if (RETURN_DOM_IMPORT) {
          /* AdoptNode() is not used because internal state is not reset
                 (e.g. the past names map of a HTMLFormElement), this is safe
                 in theory but we would rather not risk another attack vector.
                 The state that is cloned by importNode() is explicitly defined
                 by the specs. */
          returnNode = importNode.call(originalDocument, returnNode, true);
        }

        return returnNode;
      }

      return WHOLE_DOCUMENT ? body.outerHTML : body.innerHTML;
    };

    /**
     * Public method to set the configuration once
     * setConfig
     *
     * @param {Object} cfg configuration object
     */
    DOMPurify.setConfig = function (cfg) {
      _parseConfig(cfg);
      SET_CONFIG = true;
    };

    /**
     * Public method to remove the configuration
     * clearConfig
     *
     */
    DOMPurify.clearConfig = function () {
      CONFIG = null;
      SET_CONFIG = false;
    };

    /**
     * Public method to check if an attribute value is valid.
     * Uses last set config, if any. Otherwise, uses config defaults.
     * isValidAttribute
     *
     * @param  {string} tag Tag name of containing element.
     * @param  {string} attr Attribute name.
     * @param  {string} value Attribute value.
     * @return {Boolean} Returns true if `value` is valid. Otherwise, returns false.
     */
    DOMPurify.isValidAttribute = function (tag, attr, value) {
      /* Initialize shared config vars if necessary. */
      if (!CONFIG) {
        _parseConfig({});
      }
      var lcTag = tag.toLowerCase();
      var lcName = attr.toLowerCase();
      return _isValidAttribute(lcTag, lcName, value);
    };

    /**
     * AddHook
     * Public method to add DOMPurify hooks
     *
     * @param {String} entryPoint entry point for the hook to add
     * @param {Function} hookFunction function to execute
     */
    DOMPurify.addHook = function (entryPoint, hookFunction) {
      if (typeof hookFunction !== 'function') {
        return;
      }
      hooks[entryPoint] = hooks[entryPoint] || [];
      hooks[entryPoint].push(hookFunction);
    };

    /**
     * RemoveHook
     * Public method to remove a DOMPurify hook at a given entryPoint
     * (pops it from the stack of hooks if more are present)
     *
     * @param {String} entryPoint entry point for the hook to remove
     */
    DOMPurify.removeHook = function (entryPoint) {
      if (hooks[entryPoint]) {
        hooks[entryPoint].pop();
      }
    };

    /**
     * RemoveHooks
     * Public method to remove all DOMPurify hooks at a given entryPoint
     *
     * @param  {String} entryPoint entry point for the hooks to remove
     */
    DOMPurify.removeHooks = function (entryPoint) {
      if (hooks[entryPoint]) {
        hooks[entryPoint] = [];
      }
    };

    /**
     * RemoveAllHooks
     * Public method to remove all DOMPurify hooks
     *
     */
    DOMPurify.removeAllHooks = function () {
      hooks = {};
    };

    return DOMPurify;
  }

  var purify = createDOMPurify();

  var nextCreditId = 0;
  var creditToId = {};

  /**
   * A credit contains data pertaining to how to display attributions/credits for certain content on the screen.
   * @param {String} html An string representing an html code snippet
   * @param {Boolean} [showOnScreen=false] If true, the credit will be visible in the main credit container.  Otherwise, it will appear in a popover
   *
   * @alias Credit
   * @constructor
   *
   * @exception {DeveloperError} html is required.
   *
   * @example
   * //Create a credit with a tooltip, image and link
   * var credit = new Cesium.Credit('<a href="https://cesium.com/" target="_blank"><img src="/images/cesium_logo.png" title="Cesium"/></a>');
   */
  function Credit(html, showOnScreen) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("html", html);
    //>>includeEnd('debug');
    var id;
    var key = html;

    if (defined(creditToId[key])) {
      id = creditToId[key];
    } else {
      id = nextCreditId++;
      creditToId[key] = id;
    }

    showOnScreen = defaultValue(showOnScreen, false);

    // Credits are immutable so generate an id to use to optimize equal()
    this._id = id;
    this._html = html;
    this._showOnScreen = showOnScreen;
    this._element = undefined;
  }

  Object.defineProperties(Credit.prototype, {
    /**
     * The credit content
     * @memberof Credit.prototype
     * @type {String}
     * @readonly
     */
    html: {
      get: function () {
        return this._html;
      },
    },

    /**
     * @memberof Credit.prototype
     * @type {Number}
     * @readonly
     *
     * @private
     */
    id: {
      get: function () {
        return this._id;
      },
    },

    /**
     * Whether the credit should be displayed on screen or in a lightbox
     * @memberof Credit.prototype
     * @type {Boolean}
     * @readonly
     */
    showOnScreen: {
      get: function () {
        return this._showOnScreen;
      },
    },

    /**
     * Gets the credit element
     * @memberof Credit.prototype
     * @type {HTMLElement}
     * @readonly
     */
    element: {
      get: function () {
        if (!defined(this._element)) {
          var html = purify.sanitize(this._html);

          var div = document.createElement("div");
          div._creditId = this._id;
          div.style.display = "inline";
          div.innerHTML = html;

          var links = div.querySelectorAll("a");
          for (var i = 0; i < links.length; i++) {
            links[i].setAttribute("target", "_blank");
          }

          this._element = div;
        }
        return this._element;
      },
    },
  });

  /**
   * Returns true if the credits are equal
   *
   * @param {Credit} left The first credit
   * @param {Credit} right The second credit
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Credit.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) && defined(right) && left._id === right._id)
    );
  };

  /**
   * Returns true if the credits are equal
   *
   * @param {Credit} credit The credit to compare to.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Credit.prototype.equals = function (credit) {
    return Credit.equals(this, credit);
  };

  /**
   * @private
   * @param attribution
   * @return {Credit}
   */
  Credit.getIonCredit = function (attribution) {
    var showOnScreen =
      defined(attribution.collapsible) && !attribution.collapsible;
    var credit = new Credit(attribution.html, showOnScreen);

    credit._isIon = credit.html.indexOf("ion-credit.png") !== -1;
    return credit;
  };

  /**
   * Duplicates a Credit instance.
   *
   * @param {Credit} [credit] The Credit to duplicate.
   * @returns {Credit} A new Credit instance that is a duplicate of the one provided. (Returns undefined if the credit is undefined)
   */
  Credit.clone = function (credit) {
    if (defined(credit)) {
      return new Credit(credit.html, credit.showOnScreen);
    }
  };

  /**
   * The encoding that is used for a heightmap
   *
   * @enum {Number}
   */
  var HeightmapEncoding = {
    /**
     * No encoding
     *
     * @type {Number}
     * @constant
     */
    NONE: 0,

    /**
     * LERC encoding
     *
     * @type {Number}
     * @constant
     *
     * @see {@link https://github.com/Esri/lerc|The LERC specification}
     */
    LERC: 1,
  };
  var HeightmapEncoding$1 = Object.freeze(HeightmapEncoding);

  /**
   * Creates an instance of an AxisAlignedBoundingBox from the minimum and maximum points along the x, y, and z axes.
   * @alias AxisAlignedBoundingBox
   * @constructor
   *
   * @param {Cartesian3} [minimum=Cartesian3.ZERO] The minimum point along the x, y, and z axes.
   * @param {Cartesian3} [maximum=Cartesian3.ZERO] The maximum point along the x, y, and z axes.
   * @param {Cartesian3} [center] The center of the box; automatically computed if not supplied.
   *
   * @see BoundingSphere
   * @see BoundingRectangle
   */
  function AxisAlignedBoundingBox(minimum, maximum, center) {
    /**
     * The minimum point defining the bounding box.
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.minimum = Cartesian3.clone(defaultValue(minimum, Cartesian3.ZERO));

    /**
     * The maximum point defining the bounding box.
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.maximum = Cartesian3.clone(defaultValue(maximum, Cartesian3.ZERO));

    //If center was not defined, compute it.
    if (!defined(center)) {
      center = Cartesian3.midpoint(this.minimum, this.maximum, new Cartesian3());
    } else {
      center = Cartesian3.clone(center);
    }

    /**
     * The center point of the bounding box.
     * @type {Cartesian3}
     */
    this.center = center;
  }

  /**
   * Computes an instance of an AxisAlignedBoundingBox. The box is determined by
   * finding the points spaced the farthest apart on the x, y, and z axes.
   *
   * @param {Cartesian3[]} positions List of points that the bounding box will enclose.  Each point must have a <code>x</code>, <code>y</code>, and <code>z</code> properties.
   * @param {AxisAlignedBoundingBox} [result] The object onto which to store the result.
   * @returns {AxisAlignedBoundingBox} The modified result parameter or a new AxisAlignedBoundingBox instance if one was not provided.
   *
   * @example
   * // Compute an axis aligned bounding box enclosing two points.
   * var box = Cesium.AxisAlignedBoundingBox.fromPoints([new Cesium.Cartesian3(2, 0, 0), new Cesium.Cartesian3(-2, 0, 0)]);
   */
  AxisAlignedBoundingBox.fromPoints = function (positions, result) {
    if (!defined(result)) {
      result = new AxisAlignedBoundingBox();
    }

    if (!defined(positions) || positions.length === 0) {
      result.minimum = Cartesian3.clone(Cartesian3.ZERO, result.minimum);
      result.maximum = Cartesian3.clone(Cartesian3.ZERO, result.maximum);
      result.center = Cartesian3.clone(Cartesian3.ZERO, result.center);
      return result;
    }

    var minimumX = positions[0].x;
    var minimumY = positions[0].y;
    var minimumZ = positions[0].z;

    var maximumX = positions[0].x;
    var maximumY = positions[0].y;
    var maximumZ = positions[0].z;

    var length = positions.length;
    for (var i = 1; i < length; i++) {
      var p = positions[i];
      var x = p.x;
      var y = p.y;
      var z = p.z;

      minimumX = Math.min(x, minimumX);
      maximumX = Math.max(x, maximumX);
      minimumY = Math.min(y, minimumY);
      maximumY = Math.max(y, maximumY);
      minimumZ = Math.min(z, minimumZ);
      maximumZ = Math.max(z, maximumZ);
    }

    var minimum = result.minimum;
    minimum.x = minimumX;
    minimum.y = minimumY;
    minimum.z = minimumZ;

    var maximum = result.maximum;
    maximum.x = maximumX;
    maximum.y = maximumY;
    maximum.z = maximumZ;

    result.center = Cartesian3.midpoint(minimum, maximum, result.center);

    return result;
  };

  /**
   * Duplicates a AxisAlignedBoundingBox instance.
   *
   * @param {AxisAlignedBoundingBox} box The bounding box to duplicate.
   * @param {AxisAlignedBoundingBox} [result] The object onto which to store the result.
   * @returns {AxisAlignedBoundingBox} The modified result parameter or a new AxisAlignedBoundingBox instance if none was provided. (Returns undefined if box is undefined)
   */
  AxisAlignedBoundingBox.clone = function (box, result) {
    if (!defined(box)) {
      return undefined;
    }

    if (!defined(result)) {
      return new AxisAlignedBoundingBox(box.minimum, box.maximum, box.center);
    }

    result.minimum = Cartesian3.clone(box.minimum, result.minimum);
    result.maximum = Cartesian3.clone(box.maximum, result.maximum);
    result.center = Cartesian3.clone(box.center, result.center);
    return result;
  };

  /**
   * Compares the provided AxisAlignedBoundingBox componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {AxisAlignedBoundingBox} [left] The first AxisAlignedBoundingBox.
   * @param {AxisAlignedBoundingBox} [right] The second AxisAlignedBoundingBox.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  AxisAlignedBoundingBox.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Cartesian3.equals(left.center, right.center) &&
        Cartesian3.equals(left.minimum, right.minimum) &&
        Cartesian3.equals(left.maximum, right.maximum))
    );
  };

  var intersectScratch = new Cartesian3();
  /**
   * Determines which side of a plane a box is located.
   *
   * @param {AxisAlignedBoundingBox} box The bounding box to test.
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
   *                      intersects the plane.
   */
  AxisAlignedBoundingBox.intersectPlane = function (box, plane) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("box", box);
    Check.defined("plane", plane);
    //>>includeEnd('debug');

    intersectScratch = Cartesian3.subtract(
      box.maximum,
      box.minimum,
      intersectScratch
    );
    var h = Cartesian3.multiplyByScalar(intersectScratch, 0.5, intersectScratch); //The positive half diagonal
    var normal = plane.normal;
    var e =
      h.x * Math.abs(normal.x) +
      h.y * Math.abs(normal.y) +
      h.z * Math.abs(normal.z);
    var s = Cartesian3.dot(box.center, normal) + plane.distance; //signed distance from center

    if (s - e > 0) {
      return Intersect$1.INSIDE;
    }

    if (s + e < 0) {
      //Not in front because normals point inward
      return Intersect$1.OUTSIDE;
    }

    return Intersect$1.INTERSECTING;
  };

  /**
   * Duplicates this AxisAlignedBoundingBox instance.
   *
   * @param {AxisAlignedBoundingBox} [result] The object onto which to store the result.
   * @returns {AxisAlignedBoundingBox} The modified result parameter or a new AxisAlignedBoundingBox instance if one was not provided.
   */
  AxisAlignedBoundingBox.prototype.clone = function (result) {
    return AxisAlignedBoundingBox.clone(this, result);
  };

  /**
   * Determines which side of a plane this box is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
   *                      intersects the plane.
   */
  AxisAlignedBoundingBox.prototype.intersectPlane = function (plane) {
    return AxisAlignedBoundingBox.intersectPlane(this, plane);
  };

  /**
   * Compares this AxisAlignedBoundingBox against the provided AxisAlignedBoundingBox componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {AxisAlignedBoundingBox} [right] The right hand side AxisAlignedBoundingBox.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  AxisAlignedBoundingBox.prototype.equals = function (right) {
    return AxisAlignedBoundingBox.equals(this, right);
  };

  /**
   * Determine whether or not other objects are visible or hidden behind the visible horizon defined by
   * an {@link Ellipsoid} and a camera position.  The ellipsoid is assumed to be located at the
   * origin of the coordinate system.  This class uses the algorithm described in the
   * {@link https://cesium.com/blog/2013/04/25/Horizon-culling/|Horizon Culling} blog post.
   *
   * @alias EllipsoidalOccluder
   *
   * @param {Ellipsoid} ellipsoid The ellipsoid to use as an occluder.
   * @param {Cartesian3} [cameraPosition] The coordinate of the viewer/camera.  If this parameter is not
   *        specified, {@link EllipsoidalOccluder#cameraPosition} must be called before
   *        testing visibility.
   *
   * @constructor
   *
   * @example
   * // Construct an ellipsoidal occluder with radii 1.0, 1.1, and 0.9.
   * var cameraPosition = new Cesium.Cartesian3(5.0, 6.0, 7.0);
   * var occluderEllipsoid = new Cesium.Ellipsoid(1.0, 1.1, 0.9);
   * var occluder = new Cesium.EllipsoidalOccluder(occluderEllipsoid, cameraPosition);
   *
   * @private
   */
  function EllipsoidalOccluder(ellipsoid, cameraPosition) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("ellipsoid", ellipsoid);
    //>>includeEnd('debug');

    this._ellipsoid = ellipsoid;
    this._cameraPosition = new Cartesian3();
    this._cameraPositionInScaledSpace = new Cartesian3();
    this._distanceToLimbInScaledSpaceSquared = 0.0;

    // cameraPosition fills in the above values
    if (defined(cameraPosition)) {
      this.cameraPosition = cameraPosition;
    }
  }

  Object.defineProperties(EllipsoidalOccluder.prototype, {
    /**
     * Gets the occluding ellipsoid.
     * @memberof EllipsoidalOccluder.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
    /**
     * Gets or sets the position of the camera.
     * @memberof EllipsoidalOccluder.prototype
     * @type {Cartesian3}
     */
    cameraPosition: {
      get: function () {
        return this._cameraPosition;
      },
      set: function (cameraPosition) {
        // See https://cesium.com/blog/2013/04/25/Horizon-culling/
        var ellipsoid = this._ellipsoid;
        var cv = ellipsoid.transformPositionToScaledSpace(
          cameraPosition,
          this._cameraPositionInScaledSpace
        );
        var vhMagnitudeSquared = Cartesian3.magnitudeSquared(cv) - 1.0;

        Cartesian3.clone(cameraPosition, this._cameraPosition);
        this._cameraPositionInScaledSpace = cv;
        this._distanceToLimbInScaledSpaceSquared = vhMagnitudeSquared;
      },
    },
  });

  var scratchCartesian = new Cartesian3();

  /**
   * Determines whether or not a point, the <code>occludee</code>, is hidden from view by the occluder.
   *
   * @param {Cartesian3} occludee The point to test for visibility.
   * @returns {Boolean} <code>true</code> if the occludee is visible; otherwise <code>false</code>.
   *
   * @example
   * var cameraPosition = new Cesium.Cartesian3(0, 0, 2.5);
   * var ellipsoid = new Cesium.Ellipsoid(1.0, 1.1, 0.9);
   * var occluder = new Cesium.EllipsoidalOccluder(ellipsoid, cameraPosition);
   * var point = new Cesium.Cartesian3(0, -3, -3);
   * occluder.isPointVisible(point); //returns true
   */
  EllipsoidalOccluder.prototype.isPointVisible = function (occludee) {
    var ellipsoid = this._ellipsoid;
    var occludeeScaledSpacePosition = ellipsoid.transformPositionToScaledSpace(
      occludee,
      scratchCartesian
    );
    return isScaledSpacePointVisible(
      occludeeScaledSpacePosition,
      this._cameraPositionInScaledSpace,
      this._distanceToLimbInScaledSpaceSquared
    );
  };

  /**
   * Determines whether or not a point expressed in the ellipsoid scaled space, is hidden from view by the
   * occluder.  To transform a Cartesian X, Y, Z position in the coordinate system aligned with the ellipsoid
   * into the scaled space, call {@link Ellipsoid#transformPositionToScaledSpace}.
   *
   * @param {Cartesian3} occludeeScaledSpacePosition The point to test for visibility, represented in the scaled space.
   * @returns {Boolean} <code>true</code> if the occludee is visible; otherwise <code>false</code>.
   *
   * @example
   * var cameraPosition = new Cesium.Cartesian3(0, 0, 2.5);
   * var ellipsoid = new Cesium.Ellipsoid(1.0, 1.1, 0.9);
   * var occluder = new Cesium.EllipsoidalOccluder(ellipsoid, cameraPosition);
   * var point = new Cesium.Cartesian3(0, -3, -3);
   * var scaledSpacePoint = ellipsoid.transformPositionToScaledSpace(point);
   * occluder.isScaledSpacePointVisible(scaledSpacePoint); //returns true
   */
  EllipsoidalOccluder.prototype.isScaledSpacePointVisible = function (
    occludeeScaledSpacePosition
  ) {
    return isScaledSpacePointVisible(
      occludeeScaledSpacePosition,
      this._cameraPositionInScaledSpace,
      this._distanceToLimbInScaledSpaceSquared
    );
  };

  var scratchCameraPositionInScaledSpaceShrunk = new Cartesian3();

  /**
   * Similar to {@link EllipsoidalOccluder#isScaledSpacePointVisible} except tests against an
   * ellipsoid that has been shrunk by the minimum height when the minimum height is below
   * the ellipsoid. This is intended to be used with points generated by
   * {@link EllipsoidalOccluder#computeHorizonCullingPointPossiblyUnderEllipsoid} or
   * {@link EllipsoidalOccluder#computeHorizonCullingPointFromVerticesPossiblyUnderEllipsoid}.
   *
   * @param {Cartesian3} occludeeScaledSpacePosition The point to test for visibility, represented in the scaled space of the possibly-shrunk ellipsoid.
   * @returns {Boolean} <code>true</code> if the occludee is visible; otherwise <code>false</code>.
   */
  EllipsoidalOccluder.prototype.isScaledSpacePointVisiblePossiblyUnderEllipsoid = function (
    occludeeScaledSpacePosition,
    minimumHeight
  ) {
    var ellipsoid = this._ellipsoid;
    var vhMagnitudeSquared;
    var cv;

    if (
      defined(minimumHeight) &&
      minimumHeight < 0.0 &&
      ellipsoid.minimumRadius > -minimumHeight
    ) {
      // This code is similar to the cameraPosition setter, but unrolled for performance because it will be called a lot.
      cv = scratchCameraPositionInScaledSpaceShrunk;
      cv.x = this._cameraPosition.x / (ellipsoid.radii.x + minimumHeight);
      cv.y = this._cameraPosition.y / (ellipsoid.radii.y + minimumHeight);
      cv.z = this._cameraPosition.z / (ellipsoid.radii.z + minimumHeight);
      vhMagnitudeSquared = cv.x * cv.x + cv.y * cv.y + cv.z * cv.z - 1.0;
    } else {
      cv = this._cameraPositionInScaledSpace;
      vhMagnitudeSquared = this._distanceToLimbInScaledSpaceSquared;
    }

    return isScaledSpacePointVisible(
      occludeeScaledSpacePosition,
      cv,
      vhMagnitudeSquared
    );
  };

  /**
   * Computes a point that can be used for horizon culling from a list of positions.  If the point is below
   * the horizon, all of the positions are guaranteed to be below the horizon as well.  The returned point
   * is expressed in the ellipsoid-scaled space and is suitable for use with
   * {@link EllipsoidalOccluder#isScaledSpacePointVisible}.
   *
   * @param {Cartesian3} directionToPoint The direction that the computed point will lie along.
   *                     A reasonable direction to use is the direction from the center of the ellipsoid to
   *                     the center of the bounding sphere computed from the positions.  The direction need not
   *                     be normalized.
   * @param {Cartesian3[]} positions The positions from which to compute the horizon culling point.  The positions
   *                       must be expressed in a reference frame centered at the ellipsoid and aligned with the
   *                       ellipsoid's axes.
   * @param {Cartesian3} [result] The instance on which to store the result instead of allocating a new instance.
   * @returns {Cartesian3} The computed horizon culling point, expressed in the ellipsoid-scaled space.
   */
  EllipsoidalOccluder.prototype.computeHorizonCullingPoint = function (
    directionToPoint,
    positions,
    result
  ) {
    return computeHorizonCullingPointFromPositions(
      this._ellipsoid,
      directionToPoint,
      positions,
      result
    );
  };

  var scratchEllipsoidShrunk = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);

  /**
   * Similar to {@link EllipsoidalOccluder#computeHorizonCullingPoint} except computes the culling
   * point relative to an ellipsoid that has been shrunk by the minimum height when the minimum height is below
   * the ellipsoid. The returned point is expressed in the possibly-shrunk ellipsoid-scaled space and is suitable
   * for use with {@link EllipsoidalOccluder#isScaledSpacePointVisiblePossiblyUnderEllipsoid}.
   *
   * @param {Cartesian3} directionToPoint The direction that the computed point will lie along.
   *                     A reasonable direction to use is the direction from the center of the ellipsoid to
   *                     the center of the bounding sphere computed from the positions.  The direction need not
   *                     be normalized.
   * @param {Cartesian3[]} positions The positions from which to compute the horizon culling point.  The positions
   *                       must be expressed in a reference frame centered at the ellipsoid and aligned with the
   *                       ellipsoid's axes.
   * @param {Number} [minimumHeight] The minimum height of all positions. If this value is undefined, all positions are assumed to be above the ellipsoid.
   * @param {Cartesian3} [result] The instance on which to store the result instead of allocating a new instance.
   * @returns {Cartesian3} The computed horizon culling point, expressed in the possibly-shrunk ellipsoid-scaled space.
   */
  EllipsoidalOccluder.prototype.computeHorizonCullingPointPossiblyUnderEllipsoid = function (
    directionToPoint,
    positions,
    minimumHeight,
    result
  ) {
    var possiblyShrunkEllipsoid = getPossiblyShrunkEllipsoid(
      this._ellipsoid,
      minimumHeight,
      scratchEllipsoidShrunk
    );
    return computeHorizonCullingPointFromPositions(
      possiblyShrunkEllipsoid,
      directionToPoint,
      positions,
      result
    );
  };
  /**
   * Computes a point that can be used for horizon culling from a list of positions.  If the point is below
   * the horizon, all of the positions are guaranteed to be below the horizon as well.  The returned point
   * is expressed in the ellipsoid-scaled space and is suitable for use with
   * {@link EllipsoidalOccluder#isScaledSpacePointVisible}.
   *
   * @param {Cartesian3} directionToPoint The direction that the computed point will lie along.
   *                     A reasonable direction to use is the direction from the center of the ellipsoid to
   *                     the center of the bounding sphere computed from the positions.  The direction need not
   *                     be normalized.
   * @param {Number[]} vertices  The vertices from which to compute the horizon culling point.  The positions
   *                   must be expressed in a reference frame centered at the ellipsoid and aligned with the
   *                   ellipsoid's axes.
   * @param {Number} [stride=3]
   * @param {Cartesian3} [center=Cartesian3.ZERO]
   * @param {Cartesian3} [result] The instance on which to store the result instead of allocating a new instance.
   * @returns {Cartesian3} The computed horizon culling point, expressed in the ellipsoid-scaled space.
   */
  EllipsoidalOccluder.prototype.computeHorizonCullingPointFromVertices = function (
    directionToPoint,
    vertices,
    stride,
    center,
    result
  ) {
    return computeHorizonCullingPointFromVertices(
      this._ellipsoid,
      directionToPoint,
      vertices,
      stride,
      center,
      result
    );
  };

  /**
   * Similar to {@link EllipsoidalOccluder#computeHorizonCullingPointFromVertices} except computes the culling
   * point relative to an ellipsoid that has been shrunk by the minimum height when the minimum height is below
   * the ellipsoid. The returned point is expressed in the possibly-shrunk ellipsoid-scaled space and is suitable
   * for use with {@link EllipsoidalOccluder#isScaledSpacePointVisiblePossiblyUnderEllipsoid}.
   *
   * @param {Cartesian3} directionToPoint The direction that the computed point will lie along.
   *                     A reasonable direction to use is the direction from the center of the ellipsoid to
   *                     the center of the bounding sphere computed from the positions.  The direction need not
   *                     be normalized.
   * @param {Number[]} vertices  The vertices from which to compute the horizon culling point.  The positions
   *                   must be expressed in a reference frame centered at the ellipsoid and aligned with the
   *                   ellipsoid's axes.
   * @param {Number} [stride=3]
   * @param {Cartesian3} [center=Cartesian3.ZERO]
   * @param {Number} [minimumHeight] The minimum height of all vertices. If this value is undefined, all vertices are assumed to be above the ellipsoid.
   * @param {Cartesian3} [result] The instance on which to store the result instead of allocating a new instance.
   * @returns {Cartesian3} The computed horizon culling point, expressed in the possibly-shrunk ellipsoid-scaled space.
   */
  EllipsoidalOccluder.prototype.computeHorizonCullingPointFromVerticesPossiblyUnderEllipsoid = function (
    directionToPoint,
    vertices,
    stride,
    center,
    minimumHeight,
    result
  ) {
    var possiblyShrunkEllipsoid = getPossiblyShrunkEllipsoid(
      this._ellipsoid,
      minimumHeight,
      scratchEllipsoidShrunk
    );
    return computeHorizonCullingPointFromVertices(
      possiblyShrunkEllipsoid,
      directionToPoint,
      vertices,
      stride,
      center,
      result
    );
  };

  var subsampleScratch = [];

  /**
   * Computes a point that can be used for horizon culling of a rectangle.  If the point is below
   * the horizon, the ellipsoid-conforming rectangle is guaranteed to be below the horizon as well.
   * The returned point is expressed in the ellipsoid-scaled space and is suitable for use with
   * {@link EllipsoidalOccluder#isScaledSpacePointVisible}.
   *
   * @param {Rectangle} rectangle The rectangle for which to compute the horizon culling point.
   * @param {Ellipsoid} ellipsoid The ellipsoid on which the rectangle is defined.  This may be different from
   *                    the ellipsoid used by this instance for occlusion testing.
   * @param {Cartesian3} [result] The instance on which to store the result instead of allocating a new instance.
   * @returns {Cartesian3} The computed horizon culling point, expressed in the ellipsoid-scaled space.
   */
  EllipsoidalOccluder.prototype.computeHorizonCullingPointFromRectangle = function (
    rectangle,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    var positions = Rectangle.subsample(
      rectangle,
      ellipsoid,
      0.0,
      subsampleScratch
    );
    var bs = BoundingSphere.fromPoints(positions);

    // If the bounding sphere center is too close to the center of the occluder, it doesn't make
    // sense to try to horizon cull it.
    if (Cartesian3.magnitude(bs.center) < 0.1 * ellipsoid.minimumRadius) {
      return undefined;
    }

    return this.computeHorizonCullingPoint(bs.center, positions, result);
  };

  var scratchEllipsoidShrunkRadii = new Cartesian3();

  function getPossiblyShrunkEllipsoid(ellipsoid, minimumHeight, result) {
    if (
      defined(minimumHeight) &&
      minimumHeight < 0.0 &&
      ellipsoid.minimumRadius > -minimumHeight
    ) {
      var ellipsoidShrunkRadii = Cartesian3.fromElements(
        ellipsoid.radii.x + minimumHeight,
        ellipsoid.radii.y + minimumHeight,
        ellipsoid.radii.z + minimumHeight,
        scratchEllipsoidShrunkRadii
      );
      ellipsoid = Ellipsoid.fromCartesian3(ellipsoidShrunkRadii, result);
    }
    return ellipsoid;
  }

  function computeHorizonCullingPointFromPositions(
    ellipsoid,
    directionToPoint,
    positions,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("directionToPoint", directionToPoint);
    Check.defined("positions", positions);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    var scaledSpaceDirectionToPoint = computeScaledSpaceDirectionToPoint(
      ellipsoid,
      directionToPoint
    );
    var resultMagnitude = 0.0;

    for (var i = 0, len = positions.length; i < len; ++i) {
      var position = positions[i];
      var candidateMagnitude = computeMagnitude(
        ellipsoid,
        position,
        scaledSpaceDirectionToPoint
      );
      if (candidateMagnitude < 0.0) {
        // all points should face the same direction, but this one doesn't, so return undefined
        return undefined;
      }
      resultMagnitude = Math.max(resultMagnitude, candidateMagnitude);
    }

    return magnitudeToPoint(scaledSpaceDirectionToPoint, resultMagnitude, result);
  }

  var positionScratch = new Cartesian3();

  function computeHorizonCullingPointFromVertices(
    ellipsoid,
    directionToPoint,
    vertices,
    stride,
    center,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("directionToPoint", directionToPoint);
    Check.defined("vertices", vertices);
    Check.typeOf.number("stride", stride);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    stride = defaultValue(stride, 3);
    center = defaultValue(center, Cartesian3.ZERO);
    var scaledSpaceDirectionToPoint = computeScaledSpaceDirectionToPoint(
      ellipsoid,
      directionToPoint
    );
    var resultMagnitude = 0.0;

    for (var i = 0, len = vertices.length; i < len; i += stride) {
      positionScratch.x = vertices[i] + center.x;
      positionScratch.y = vertices[i + 1] + center.y;
      positionScratch.z = vertices[i + 2] + center.z;

      var candidateMagnitude = computeMagnitude(
        ellipsoid,
        positionScratch,
        scaledSpaceDirectionToPoint
      );
      if (candidateMagnitude < 0.0) {
        // all points should face the same direction, but this one doesn't, so return undefined
        return undefined;
      }
      resultMagnitude = Math.max(resultMagnitude, candidateMagnitude);
    }

    return magnitudeToPoint(scaledSpaceDirectionToPoint, resultMagnitude, result);
  }

  function isScaledSpacePointVisible(
    occludeeScaledSpacePosition,
    cameraPositionInScaledSpace,
    distanceToLimbInScaledSpaceSquared
  ) {
    // See https://cesium.com/blog/2013/04/25/Horizon-culling/
    var cv = cameraPositionInScaledSpace;
    var vhMagnitudeSquared = distanceToLimbInScaledSpaceSquared;
    var vt = Cartesian3.subtract(
      occludeeScaledSpacePosition,
      cv,
      scratchCartesian
    );
    var vtDotVc = -Cartesian3.dot(vt, cv);
    // If vhMagnitudeSquared < 0 then we are below the surface of the ellipsoid and
    // in this case, set the culling plane to be on V.
    var isOccluded =
      vhMagnitudeSquared < 0
        ? vtDotVc > 0
        : vtDotVc > vhMagnitudeSquared &&
          (vtDotVc * vtDotVc) / Cartesian3.magnitudeSquared(vt) >
            vhMagnitudeSquared;
    return !isOccluded;
  }

  var scaledSpaceScratch = new Cartesian3();
  var directionScratch = new Cartesian3();

  function computeMagnitude(ellipsoid, position, scaledSpaceDirectionToPoint) {
    var scaledSpacePosition = ellipsoid.transformPositionToScaledSpace(
      position,
      scaledSpaceScratch
    );
    var magnitudeSquared = Cartesian3.magnitudeSquared(scaledSpacePosition);
    var magnitude = Math.sqrt(magnitudeSquared);
    var direction = Cartesian3.divideByScalar(
      scaledSpacePosition,
      magnitude,
      directionScratch
    );

    // For the purpose of this computation, points below the ellipsoid are consider to be on it instead.
    magnitudeSquared = Math.max(1.0, magnitudeSquared);
    magnitude = Math.max(1.0, magnitude);

    var cosAlpha = Cartesian3.dot(direction, scaledSpaceDirectionToPoint);
    var sinAlpha = Cartesian3.magnitude(
      Cartesian3.cross(direction, scaledSpaceDirectionToPoint, direction)
    );
    var cosBeta = 1.0 / magnitude;
    var sinBeta = Math.sqrt(magnitudeSquared - 1.0) * cosBeta;

    return 1.0 / (cosAlpha * cosBeta - sinAlpha * sinBeta);
  }

  function magnitudeToPoint(
    scaledSpaceDirectionToPoint,
    resultMagnitude,
    result
  ) {
    // The horizon culling point is undefined if there were no positions from which to compute it,
    // the directionToPoint is pointing opposite all of the positions,  or if we computed NaN or infinity.
    if (
      resultMagnitude <= 0.0 ||
      resultMagnitude === 1.0 / 0.0 ||
      resultMagnitude !== resultMagnitude
    ) {
      return undefined;
    }

    return Cartesian3.multiplyByScalar(
      scaledSpaceDirectionToPoint,
      resultMagnitude,
      result
    );
  }

  var directionToPointScratch = new Cartesian3();

  function computeScaledSpaceDirectionToPoint(ellipsoid, directionToPoint) {
    if (Cartesian3.equals(directionToPoint, Cartesian3.ZERO)) {
      return directionToPoint;
    }

    ellipsoid.transformPositionToScaledSpace(
      directionToPoint,
      directionToPointScratch
    );
    return Cartesian3.normalize(directionToPointScratch, directionToPointScratch);
  }

  /**
   * Defines functions for 2nd order polynomial functions of one variable with only real coefficients.
   *
   * @namespace QuadraticRealPolynomial
   */
  var QuadraticRealPolynomial = {};

  /**
   * Provides the discriminant of the quadratic equation from the supplied coefficients.
   *
   * @param {Number} a The coefficient of the 2nd order monomial.
   * @param {Number} b The coefficient of the 1st order monomial.
   * @param {Number} c The coefficient of the 0th order monomial.
   * @returns {Number} The value of the discriminant.
   */
  QuadraticRealPolynomial.computeDiscriminant = function (a, b, c) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof a !== "number") {
      throw new DeveloperError("a is a required number.");
    }
    if (typeof b !== "number") {
      throw new DeveloperError("b is a required number.");
    }
    if (typeof c !== "number") {
      throw new DeveloperError("c is a required number.");
    }
    //>>includeEnd('debug');

    var discriminant = b * b - 4.0 * a * c;
    return discriminant;
  };

  function addWithCancellationCheck(left, right, tolerance) {
    var difference = left + right;
    if (
      CesiumMath.sign(left) !== CesiumMath.sign(right) &&
      Math.abs(difference / Math.max(Math.abs(left), Math.abs(right))) < tolerance
    ) {
      return 0.0;
    }

    return difference;
  }

  /**
   * Provides the real valued roots of the quadratic polynomial with the provided coefficients.
   *
   * @param {Number} a The coefficient of the 2nd order monomial.
   * @param {Number} b The coefficient of the 1st order monomial.
   * @param {Number} c The coefficient of the 0th order monomial.
   * @returns {Number[]} The real valued roots.
   */
  QuadraticRealPolynomial.computeRealRoots = function (a, b, c) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof a !== "number") {
      throw new DeveloperError("a is a required number.");
    }
    if (typeof b !== "number") {
      throw new DeveloperError("b is a required number.");
    }
    if (typeof c !== "number") {
      throw new DeveloperError("c is a required number.");
    }
    //>>includeEnd('debug');

    var ratio;
    if (a === 0.0) {
      if (b === 0.0) {
        // Constant function: c = 0.
        return [];
      }

      // Linear function: b * x + c = 0.
      return [-c / b];
    } else if (b === 0.0) {
      if (c === 0.0) {
        // 2nd order monomial: a * x^2 = 0.
        return [0.0, 0.0];
      }

      var cMagnitude = Math.abs(c);
      var aMagnitude = Math.abs(a);

      if (
        cMagnitude < aMagnitude &&
        cMagnitude / aMagnitude < CesiumMath.EPSILON14
      ) {
        // c ~= 0.0.
        // 2nd order monomial: a * x^2 = 0.
        return [0.0, 0.0];
      } else if (
        cMagnitude > aMagnitude &&
        aMagnitude / cMagnitude < CesiumMath.EPSILON14
      ) {
        // a ~= 0.0.
        // Constant function: c = 0.
        return [];
      }

      // a * x^2 + c = 0
      ratio = -c / a;

      if (ratio < 0.0) {
        // Both roots are complex.
        return [];
      }

      // Both roots are real.
      var root = Math.sqrt(ratio);
      return [-root, root];
    } else if (c === 0.0) {
      // a * x^2 + b * x = 0
      ratio = -b / a;
      if (ratio < 0.0) {
        return [ratio, 0.0];
      }

      return [0.0, ratio];
    }

    // a * x^2 + b * x + c = 0
    var b2 = b * b;
    var four_ac = 4.0 * a * c;
    var radicand = addWithCancellationCheck(b2, -four_ac, CesiumMath.EPSILON14);

    if (radicand < 0.0) {
      // Both roots are complex.
      return [];
    }

    var q =
      -0.5 *
      addWithCancellationCheck(
        b,
        CesiumMath.sign(b) * Math.sqrt(radicand),
        CesiumMath.EPSILON14
      );
    if (b > 0.0) {
      return [q / a, c / q];
    }

    return [c / q, q / a];
  };

  /**
   * Defines functions for 3rd order polynomial functions of one variable with only real coefficients.
   *
   * @namespace CubicRealPolynomial
   */
  var CubicRealPolynomial = {};

  /**
   * Provides the discriminant of the cubic equation from the supplied coefficients.
   *
   * @param {Number} a The coefficient of the 3rd order monomial.
   * @param {Number} b The coefficient of the 2nd order monomial.
   * @param {Number} c The coefficient of the 1st order monomial.
   * @param {Number} d The coefficient of the 0th order monomial.
   * @returns {Number} The value of the discriminant.
   */
  CubicRealPolynomial.computeDiscriminant = function (a, b, c, d) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof a !== "number") {
      throw new DeveloperError("a is a required number.");
    }
    if (typeof b !== "number") {
      throw new DeveloperError("b is a required number.");
    }
    if (typeof c !== "number") {
      throw new DeveloperError("c is a required number.");
    }
    if (typeof d !== "number") {
      throw new DeveloperError("d is a required number.");
    }
    //>>includeEnd('debug');

    var a2 = a * a;
    var b2 = b * b;
    var c2 = c * c;
    var d2 = d * d;

    var discriminant =
      18.0 * a * b * c * d +
      b2 * c2 -
      27.0 * a2 * d2 -
      4.0 * (a * c2 * c + b2 * b * d);
    return discriminant;
  };

  function computeRealRoots(a, b, c, d) {
    var A = a;
    var B = b / 3.0;
    var C = c / 3.0;
    var D = d;

    var AC = A * C;
    var BD = B * D;
    var B2 = B * B;
    var C2 = C * C;
    var delta1 = A * C - B2;
    var delta2 = A * D - B * C;
    var delta3 = B * D - C2;

    var discriminant = 4.0 * delta1 * delta3 - delta2 * delta2;
    var temp;
    var temp1;

    if (discriminant < 0.0) {
      var ABar;
      var CBar;
      var DBar;

      if (B2 * BD >= AC * C2) {
        ABar = A;
        CBar = delta1;
        DBar = -2.0 * B * delta1 + A * delta2;
      } else {
        ABar = D;
        CBar = delta3;
        DBar = -D * delta2 + 2.0 * C * delta3;
      }

      var s = DBar < 0.0 ? -1.0 : 1.0; // This is not Math.Sign()!
      var temp0 = -s * Math.abs(ABar) * Math.sqrt(-discriminant);
      temp1 = -DBar + temp0;

      var x = temp1 / 2.0;
      var p = x < 0.0 ? -Math.pow(-x, 1.0 / 3.0) : Math.pow(x, 1.0 / 3.0);
      var q = temp1 === temp0 ? -p : -CBar / p;

      temp = CBar <= 0.0 ? p + q : -DBar / (p * p + q * q + CBar);

      if (B2 * BD >= AC * C2) {
        return [(temp - B) / A];
      }

      return [-D / (temp + C)];
    }

    var CBarA = delta1;
    var DBarA = -2.0 * B * delta1 + A * delta2;

    var CBarD = delta3;
    var DBarD = -D * delta2 + 2.0 * C * delta3;

    var squareRootOfDiscriminant = Math.sqrt(discriminant);
    var halfSquareRootOf3 = Math.sqrt(3.0) / 2.0;

    var theta = Math.abs(Math.atan2(A * squareRootOfDiscriminant, -DBarA) / 3.0);
    temp = 2.0 * Math.sqrt(-CBarA);
    var cosine = Math.cos(theta);
    temp1 = temp * cosine;
    var temp3 = temp * (-cosine / 2.0 - halfSquareRootOf3 * Math.sin(theta));

    var numeratorLarge = temp1 + temp3 > 2.0 * B ? temp1 - B : temp3 - B;
    var denominatorLarge = A;

    var root1 = numeratorLarge / denominatorLarge;

    theta = Math.abs(Math.atan2(D * squareRootOfDiscriminant, -DBarD) / 3.0);
    temp = 2.0 * Math.sqrt(-CBarD);
    cosine = Math.cos(theta);
    temp1 = temp * cosine;
    temp3 = temp * (-cosine / 2.0 - halfSquareRootOf3 * Math.sin(theta));

    var numeratorSmall = -D;
    var denominatorSmall = temp1 + temp3 < 2.0 * C ? temp1 + C : temp3 + C;

    var root3 = numeratorSmall / denominatorSmall;

    var E = denominatorLarge * denominatorSmall;
    var F =
      -numeratorLarge * denominatorSmall - denominatorLarge * numeratorSmall;
    var G = numeratorLarge * numeratorSmall;

    var root2 = (C * F - B * G) / (-B * F + C * E);

    if (root1 <= root2) {
      if (root1 <= root3) {
        if (root2 <= root3) {
          return [root1, root2, root3];
        }
        return [root1, root3, root2];
      }
      return [root3, root1, root2];
    }
    if (root1 <= root3) {
      return [root2, root1, root3];
    }
    if (root2 <= root3) {
      return [root2, root3, root1];
    }
    return [root3, root2, root1];
  }

  /**
   * Provides the real valued roots of the cubic polynomial with the provided coefficients.
   *
   * @param {Number} a The coefficient of the 3rd order monomial.
   * @param {Number} b The coefficient of the 2nd order monomial.
   * @param {Number} c The coefficient of the 1st order monomial.
   * @param {Number} d The coefficient of the 0th order monomial.
   * @returns {Number[]} The real valued roots.
   */
  CubicRealPolynomial.computeRealRoots = function (a, b, c, d) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof a !== "number") {
      throw new DeveloperError("a is a required number.");
    }
    if (typeof b !== "number") {
      throw new DeveloperError("b is a required number.");
    }
    if (typeof c !== "number") {
      throw new DeveloperError("c is a required number.");
    }
    if (typeof d !== "number") {
      throw new DeveloperError("d is a required number.");
    }
    //>>includeEnd('debug');

    var roots;
    var ratio;
    if (a === 0.0) {
      // Quadratic function: b * x^2 + c * x + d = 0.
      return QuadraticRealPolynomial.computeRealRoots(b, c, d);
    } else if (b === 0.0) {
      if (c === 0.0) {
        if (d === 0.0) {
          // 3rd order monomial: a * x^3 = 0.
          return [0.0, 0.0, 0.0];
        }

        // a * x^3 + d = 0
        ratio = -d / a;
        var root =
          ratio < 0.0 ? -Math.pow(-ratio, 1.0 / 3.0) : Math.pow(ratio, 1.0 / 3.0);
        return [root, root, root];
      } else if (d === 0.0) {
        // x * (a * x^2 + c) = 0.
        roots = QuadraticRealPolynomial.computeRealRoots(a, 0, c);

        // Return the roots in ascending order.
        if (roots.Length === 0) {
          return [0.0];
        }
        return [roots[0], 0.0, roots[1]];
      }

      // Deflated cubic polynomial: a * x^3 + c * x + d= 0.
      return computeRealRoots(a, 0, c, d);
    } else if (c === 0.0) {
      if (d === 0.0) {
        // x^2 * (a * x + b) = 0.
        ratio = -b / a;
        if (ratio < 0.0) {
          return [ratio, 0.0, 0.0];
        }
        return [0.0, 0.0, ratio];
      }
      // a * x^3 + b * x^2 + d = 0.
      return computeRealRoots(a, b, 0, d);
    } else if (d === 0.0) {
      // x * (a * x^2 + b * x + c) = 0
      roots = QuadraticRealPolynomial.computeRealRoots(a, b, c);

      // Return the roots in ascending order.
      if (roots.length === 0) {
        return [0.0];
      } else if (roots[1] <= 0.0) {
        return [roots[0], roots[1], 0.0];
      } else if (roots[0] >= 0.0) {
        return [0.0, roots[0], roots[1]];
      }
      return [roots[0], 0.0, roots[1]];
    }

    return computeRealRoots(a, b, c, d);
  };

  /**
   * Defines functions for 4th order polynomial functions of one variable with only real coefficients.
   *
   * @namespace QuarticRealPolynomial
   */
  var QuarticRealPolynomial = {};

  /**
   * Provides the discriminant of the quartic equation from the supplied coefficients.
   *
   * @param {Number} a The coefficient of the 4th order monomial.
   * @param {Number} b The coefficient of the 3rd order monomial.
   * @param {Number} c The coefficient of the 2nd order monomial.
   * @param {Number} d The coefficient of the 1st order monomial.
   * @param {Number} e The coefficient of the 0th order monomial.
   * @returns {Number} The value of the discriminant.
   */
  QuarticRealPolynomial.computeDiscriminant = function (a, b, c, d, e) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof a !== "number") {
      throw new DeveloperError("a is a required number.");
    }
    if (typeof b !== "number") {
      throw new DeveloperError("b is a required number.");
    }
    if (typeof c !== "number") {
      throw new DeveloperError("c is a required number.");
    }
    if (typeof d !== "number") {
      throw new DeveloperError("d is a required number.");
    }
    if (typeof e !== "number") {
      throw new DeveloperError("e is a required number.");
    }
    //>>includeEnd('debug');

    var a2 = a * a;
    var a3 = a2 * a;
    var b2 = b * b;
    var b3 = b2 * b;
    var c2 = c * c;
    var c3 = c2 * c;
    var d2 = d * d;
    var d3 = d2 * d;
    var e2 = e * e;
    var e3 = e2 * e;

    var discriminant =
      b2 * c2 * d2 -
      4.0 * b3 * d3 -
      4.0 * a * c3 * d2 +
      18 * a * b * c * d3 -
      27.0 * a2 * d2 * d2 +
      256.0 * a3 * e3 +
      e *
        (18.0 * b3 * c * d -
          4.0 * b2 * c3 +
          16.0 * a * c2 * c2 -
          80.0 * a * b * c2 * d -
          6.0 * a * b2 * d2 +
          144.0 * a2 * c * d2) +
      e2 *
        (144.0 * a * b2 * c -
          27.0 * b2 * b2 -
          128.0 * a2 * c2 -
          192.0 * a2 * b * d);
    return discriminant;
  };

  function original(a3, a2, a1, a0) {
    var a3Squared = a3 * a3;

    var p = a2 - (3.0 * a3Squared) / 8.0;
    var q = a1 - (a2 * a3) / 2.0 + (a3Squared * a3) / 8.0;
    var r =
      a0 -
      (a1 * a3) / 4.0 +
      (a2 * a3Squared) / 16.0 -
      (3.0 * a3Squared * a3Squared) / 256.0;

    // Find the roots of the cubic equations:  h^6 + 2 p h^4 + (p^2 - 4 r) h^2 - q^2 = 0.
    var cubicRoots = CubicRealPolynomial.computeRealRoots(
      1.0,
      2.0 * p,
      p * p - 4.0 * r,
      -q * q
    );

    if (cubicRoots.length > 0) {
      var temp = -a3 / 4.0;

      // Use the largest positive root.
      var hSquared = cubicRoots[cubicRoots.length - 1];

      if (Math.abs(hSquared) < CesiumMath.EPSILON14) {
        // y^4 + p y^2 + r = 0.
        var roots = QuadraticRealPolynomial.computeRealRoots(1.0, p, r);

        if (roots.length === 2) {
          var root0 = roots[0];
          var root1 = roots[1];

          var y;
          if (root0 >= 0.0 && root1 >= 0.0) {
            var y0 = Math.sqrt(root0);
            var y1 = Math.sqrt(root1);

            return [temp - y1, temp - y0, temp + y0, temp + y1];
          } else if (root0 >= 0.0 && root1 < 0.0) {
            y = Math.sqrt(root0);
            return [temp - y, temp + y];
          } else if (root0 < 0.0 && root1 >= 0.0) {
            y = Math.sqrt(root1);
            return [temp - y, temp + y];
          }
        }
        return [];
      } else if (hSquared > 0.0) {
        var h = Math.sqrt(hSquared);

        var m = (p + hSquared - q / h) / 2.0;
        var n = (p + hSquared + q / h) / 2.0;

        // Now solve the two quadratic factors:  (y^2 + h y + m)(y^2 - h y + n);
        var roots1 = QuadraticRealPolynomial.computeRealRoots(1.0, h, m);
        var roots2 = QuadraticRealPolynomial.computeRealRoots(1.0, -h, n);

        if (roots1.length !== 0) {
          roots1[0] += temp;
          roots1[1] += temp;

          if (roots2.length !== 0) {
            roots2[0] += temp;
            roots2[1] += temp;

            if (roots1[1] <= roots2[0]) {
              return [roots1[0], roots1[1], roots2[0], roots2[1]];
            } else if (roots2[1] <= roots1[0]) {
              return [roots2[0], roots2[1], roots1[0], roots1[1]];
            } else if (roots1[0] >= roots2[0] && roots1[1] <= roots2[1]) {
              return [roots2[0], roots1[0], roots1[1], roots2[1]];
            } else if (roots2[0] >= roots1[0] && roots2[1] <= roots1[1]) {
              return [roots1[0], roots2[0], roots2[1], roots1[1]];
            } else if (roots1[0] > roots2[0] && roots1[0] < roots2[1]) {
              return [roots2[0], roots1[0], roots2[1], roots1[1]];
            }
            return [roots1[0], roots2[0], roots1[1], roots2[1]];
          }
          return roots1;
        }

        if (roots2.length !== 0) {
          roots2[0] += temp;
          roots2[1] += temp;

          return roots2;
        }
        return [];
      }
    }
    return [];
  }

  function neumark(a3, a2, a1, a0) {
    var a1Squared = a1 * a1;
    var a2Squared = a2 * a2;
    var a3Squared = a3 * a3;

    var p = -2.0 * a2;
    var q = a1 * a3 + a2Squared - 4.0 * a0;
    var r = a3Squared * a0 - a1 * a2 * a3 + a1Squared;

    var cubicRoots = CubicRealPolynomial.computeRealRoots(1.0, p, q, r);

    if (cubicRoots.length > 0) {
      // Use the most positive root
      var y = cubicRoots[0];

      var temp = a2 - y;
      var tempSquared = temp * temp;

      var g1 = a3 / 2.0;
      var h1 = temp / 2.0;

      var m = tempSquared - 4.0 * a0;
      var mError = tempSquared + 4.0 * Math.abs(a0);

      var n = a3Squared - 4.0 * y;
      var nError = a3Squared + 4.0 * Math.abs(y);

      var g2;
      var h2;

      if (y < 0.0 || m * nError < n * mError) {
        var squareRootOfN = Math.sqrt(n);
        g2 = squareRootOfN / 2.0;
        h2 = squareRootOfN === 0.0 ? 0.0 : (a3 * h1 - a1) / squareRootOfN;
      } else {
        var squareRootOfM = Math.sqrt(m);
        g2 = squareRootOfM === 0.0 ? 0.0 : (a3 * h1 - a1) / squareRootOfM;
        h2 = squareRootOfM / 2.0;
      }

      var G;
      var g;
      if (g1 === 0.0 && g2 === 0.0) {
        G = 0.0;
        g = 0.0;
      } else if (CesiumMath.sign(g1) === CesiumMath.sign(g2)) {
        G = g1 + g2;
        g = y / G;
      } else {
        g = g1 - g2;
        G = y / g;
      }

      var H;
      var h;
      if (h1 === 0.0 && h2 === 0.0) {
        H = 0.0;
        h = 0.0;
      } else if (CesiumMath.sign(h1) === CesiumMath.sign(h2)) {
        H = h1 + h2;
        h = a0 / H;
      } else {
        h = h1 - h2;
        H = a0 / h;
      }

      // Now solve the two quadratic factors:  (y^2 + G y + H)(y^2 + g y + h);
      var roots1 = QuadraticRealPolynomial.computeRealRoots(1.0, G, H);
      var roots2 = QuadraticRealPolynomial.computeRealRoots(1.0, g, h);

      if (roots1.length !== 0) {
        if (roots2.length !== 0) {
          if (roots1[1] <= roots2[0]) {
            return [roots1[0], roots1[1], roots2[0], roots2[1]];
          } else if (roots2[1] <= roots1[0]) {
            return [roots2[0], roots2[1], roots1[0], roots1[1]];
          } else if (roots1[0] >= roots2[0] && roots1[1] <= roots2[1]) {
            return [roots2[0], roots1[0], roots1[1], roots2[1]];
          } else if (roots2[0] >= roots1[0] && roots2[1] <= roots1[1]) {
            return [roots1[0], roots2[0], roots2[1], roots1[1]];
          } else if (roots1[0] > roots2[0] && roots1[0] < roots2[1]) {
            return [roots2[0], roots1[0], roots2[1], roots1[1]];
          }
          return [roots1[0], roots2[0], roots1[1], roots2[1]];
        }
        return roots1;
      }
      if (roots2.length !== 0) {
        return roots2;
      }
    }
    return [];
  }

  /**
   * Provides the real valued roots of the quartic polynomial with the provided coefficients.
   *
   * @param {Number} a The coefficient of the 4th order monomial.
   * @param {Number} b The coefficient of the 3rd order monomial.
   * @param {Number} c The coefficient of the 2nd order monomial.
   * @param {Number} d The coefficient of the 1st order monomial.
   * @param {Number} e The coefficient of the 0th order monomial.
   * @returns {Number[]} The real valued roots.
   */
  QuarticRealPolynomial.computeRealRoots = function (a, b, c, d, e) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof a !== "number") {
      throw new DeveloperError("a is a required number.");
    }
    if (typeof b !== "number") {
      throw new DeveloperError("b is a required number.");
    }
    if (typeof c !== "number") {
      throw new DeveloperError("c is a required number.");
    }
    if (typeof d !== "number") {
      throw new DeveloperError("d is a required number.");
    }
    if (typeof e !== "number") {
      throw new DeveloperError("e is a required number.");
    }
    //>>includeEnd('debug');

    if (Math.abs(a) < CesiumMath.EPSILON15) {
      return CubicRealPolynomial.computeRealRoots(b, c, d, e);
    }
    var a3 = b / a;
    var a2 = c / a;
    var a1 = d / a;
    var a0 = e / a;

    var k = a3 < 0.0 ? 1 : 0;
    k += a2 < 0.0 ? k + 1 : k;
    k += a1 < 0.0 ? k + 1 : k;
    k += a0 < 0.0 ? k + 1 : k;

    switch (k) {
      case 0:
        return original(a3, a2, a1, a0);
      case 1:
        return neumark(a3, a2, a1, a0);
      case 2:
        return neumark(a3, a2, a1, a0);
      case 3:
        return original(a3, a2, a1, a0);
      case 4:
        return original(a3, a2, a1, a0);
      case 5:
        return neumark(a3, a2, a1, a0);
      case 6:
        return original(a3, a2, a1, a0);
      case 7:
        return original(a3, a2, a1, a0);
      case 8:
        return neumark(a3, a2, a1, a0);
      case 9:
        return original(a3, a2, a1, a0);
      case 10:
        return original(a3, a2, a1, a0);
      case 11:
        return neumark(a3, a2, a1, a0);
      case 12:
        return original(a3, a2, a1, a0);
      case 13:
        return original(a3, a2, a1, a0);
      case 14:
        return original(a3, a2, a1, a0);
      case 15:
        return original(a3, a2, a1, a0);
      default:
        return undefined;
    }
  };

  /**
   * Represents a ray that extends infinitely from the provided origin in the provided direction.
   * @alias Ray
   * @constructor
   *
   * @param {Cartesian3} [origin=Cartesian3.ZERO] The origin of the ray.
   * @param {Cartesian3} [direction=Cartesian3.ZERO] The direction of the ray.
   */
  function Ray(origin, direction) {
    direction = Cartesian3.clone(defaultValue(direction, Cartesian3.ZERO));
    if (!Cartesian3.equals(direction, Cartesian3.ZERO)) {
      Cartesian3.normalize(direction, direction);
    }

    /**
     * The origin of the ray.
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.origin = Cartesian3.clone(defaultValue(origin, Cartesian3.ZERO));

    /**
     * The direction of the ray.
     * @type {Cartesian3}
     */
    this.direction = direction;
  }

  /**
   * Duplicates a Ray instance.
   *
   * @param {Ray} ray The ray to duplicate.
   * @param {Ray} [result] The object onto which to store the result.
   * @returns {Ray} The modified result parameter or a new Ray instance if one was not provided. (Returns undefined if ray is undefined)
   */
  Ray.clone = function (ray, result) {
    if (!defined(ray)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Ray(ray.origin, ray.direction);
    }
    result.origin = Cartesian3.clone(ray.origin);
    result.direction = Cartesian3.clone(ray.direction);
    return result;
  };

  /**
   * Computes the point along the ray given by r(t) = o + t*d,
   * where o is the origin of the ray and d is the direction.
   *
   * @param {Ray} ray The ray.
   * @param {Number} t A scalar value.
   * @param {Cartesian3} [result] The object in which the result will be stored.
   * @returns {Cartesian3} The modified result parameter, or a new instance if none was provided.
   *
   * @example
   * //Get the first intersection point of a ray and an ellipsoid.
   * var intersection = Cesium.IntersectionTests.rayEllipsoid(ray, ellipsoid);
   * var point = Cesium.Ray.getPoint(ray, intersection.start);
   */
  Ray.getPoint = function (ray, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("ray", ray);
    Check.typeOf.number("t", t);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    result = Cartesian3.multiplyByScalar(ray.direction, t, result);
    return Cartesian3.add(ray.origin, result, result);
  };

  /**
   * Functions for computing the intersection between geometries such as rays, planes, triangles, and ellipsoids.
   *
   * @namespace IntersectionTests
   */
  var IntersectionTests = {};

  /**
   * Computes the intersection of a ray and a plane.
   *
   * @param {Ray} ray The ray.
   * @param {Plane} plane The plane.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The intersection point or undefined if there is no intersections.
   */
  IntersectionTests.rayPlane = function (ray, plane, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(ray)) {
      throw new DeveloperError("ray is required.");
    }
    if (!defined(plane)) {
      throw new DeveloperError("plane is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    var origin = ray.origin;
    var direction = ray.direction;
    var normal = plane.normal;
    var denominator = Cartesian3.dot(normal, direction);

    if (Math.abs(denominator) < CesiumMath.EPSILON15) {
      // Ray is parallel to plane.  The ray may be in the polygon's plane.
      return undefined;
    }

    var t = (-plane.distance - Cartesian3.dot(normal, origin)) / denominator;

    if (t < 0) {
      return undefined;
    }

    result = Cartesian3.multiplyByScalar(direction, t, result);
    return Cartesian3.add(origin, result, result);
  };

  var scratchEdge0 = new Cartesian3();
  var scratchEdge1 = new Cartesian3();
  var scratchPVec = new Cartesian3();
  var scratchTVec = new Cartesian3();
  var scratchQVec = new Cartesian3();

  /**
   * Computes the intersection of a ray and a triangle as a parametric distance along the input ray. The result is negative when the triangle is behind the ray.
   *
   * Implements {@link https://cadxfem.org/inf/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf|
   * Fast Minimum Storage Ray/Triangle Intersection} by Tomas Moller and Ben Trumbore.
   *
   * @memberof IntersectionTests
   *
   * @param {Ray} ray The ray.
   * @param {Cartesian3} p0 The first vertex of the triangle.
   * @param {Cartesian3} p1 The second vertex of the triangle.
   * @param {Cartesian3} p2 The third vertex of the triangle.
   * @param {Boolean} [cullBackFaces=false] If <code>true</code>, will only compute an intersection with the front face of the triangle
   *                  and return undefined for intersections with the back face.
   * @returns {Number} The intersection as a parametric distance along the ray, or undefined if there is no intersection.
   */
  IntersectionTests.rayTriangleParametric = function (
    ray,
    p0,
    p1,
    p2,
    cullBackFaces
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(ray)) {
      throw new DeveloperError("ray is required.");
    }
    if (!defined(p0)) {
      throw new DeveloperError("p0 is required.");
    }
    if (!defined(p1)) {
      throw new DeveloperError("p1 is required.");
    }
    if (!defined(p2)) {
      throw new DeveloperError("p2 is required.");
    }
    //>>includeEnd('debug');

    cullBackFaces = defaultValue(cullBackFaces, false);

    var origin = ray.origin;
    var direction = ray.direction;

    var edge0 = Cartesian3.subtract(p1, p0, scratchEdge0);
    var edge1 = Cartesian3.subtract(p2, p0, scratchEdge1);

    var p = Cartesian3.cross(direction, edge1, scratchPVec);
    var det = Cartesian3.dot(edge0, p);

    var tvec;
    var q;

    var u;
    var v;
    var t;

    if (cullBackFaces) {
      if (det < CesiumMath.EPSILON6) {
        return undefined;
      }

      tvec = Cartesian3.subtract(origin, p0, scratchTVec);
      u = Cartesian3.dot(tvec, p);
      if (u < 0.0 || u > det) {
        return undefined;
      }

      q = Cartesian3.cross(tvec, edge0, scratchQVec);

      v = Cartesian3.dot(direction, q);
      if (v < 0.0 || u + v > det) {
        return undefined;
      }

      t = Cartesian3.dot(edge1, q) / det;
    } else {
      if (Math.abs(det) < CesiumMath.EPSILON6) {
        return undefined;
      }
      var invDet = 1.0 / det;

      tvec = Cartesian3.subtract(origin, p0, scratchTVec);
      u = Cartesian3.dot(tvec, p) * invDet;
      if (u < 0.0 || u > 1.0) {
        return undefined;
      }

      q = Cartesian3.cross(tvec, edge0, scratchQVec);

      v = Cartesian3.dot(direction, q) * invDet;
      if (v < 0.0 || u + v > 1.0) {
        return undefined;
      }

      t = Cartesian3.dot(edge1, q) * invDet;
    }

    return t;
  };

  /**
   * Computes the intersection of a ray and a triangle as a Cartesian3 coordinate.
   *
   * Implements {@link https://cadxfem.org/inf/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf|
   * Fast Minimum Storage Ray/Triangle Intersection} by Tomas Moller and Ben Trumbore.
   *
   * @memberof IntersectionTests
   *
   * @param {Ray} ray The ray.
   * @param {Cartesian3} p0 The first vertex of the triangle.
   * @param {Cartesian3} p1 The second vertex of the triangle.
   * @param {Cartesian3} p2 The third vertex of the triangle.
   * @param {Boolean} [cullBackFaces=false] If <code>true</code>, will only compute an intersection with the front face of the triangle
   *                  and return undefined for intersections with the back face.
   * @param {Cartesian3} [result] The <code>Cartesian3</code> onto which to store the result.
   * @returns {Cartesian3} The intersection point or undefined if there is no intersections.
   */
  IntersectionTests.rayTriangle = function (
    ray,
    p0,
    p1,
    p2,
    cullBackFaces,
    result
  ) {
    var t = IntersectionTests.rayTriangleParametric(
      ray,
      p0,
      p1,
      p2,
      cullBackFaces
    );
    if (!defined(t) || t < 0.0) {
      return undefined;
    }

    if (!defined(result)) {
      result = new Cartesian3();
    }

    Cartesian3.multiplyByScalar(ray.direction, t, result);
    return Cartesian3.add(ray.origin, result, result);
  };

  var scratchLineSegmentTriangleRay = new Ray();

  /**
   * Computes the intersection of a line segment and a triangle.
   * @memberof IntersectionTests
   *
   * @param {Cartesian3} v0 The an end point of the line segment.
   * @param {Cartesian3} v1 The other end point of the line segment.
   * @param {Cartesian3} p0 The first vertex of the triangle.
   * @param {Cartesian3} p1 The second vertex of the triangle.
   * @param {Cartesian3} p2 The third vertex of the triangle.
   * @param {Boolean} [cullBackFaces=false] If <code>true</code>, will only compute an intersection with the front face of the triangle
   *                  and return undefined for intersections with the back face.
   * @param {Cartesian3} [result] The <code>Cartesian3</code> onto which to store the result.
   * @returns {Cartesian3} The intersection point or undefined if there is no intersections.
   */
  IntersectionTests.lineSegmentTriangle = function (
    v0,
    v1,
    p0,
    p1,
    p2,
    cullBackFaces,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(v0)) {
      throw new DeveloperError("v0 is required.");
    }
    if (!defined(v1)) {
      throw new DeveloperError("v1 is required.");
    }
    if (!defined(p0)) {
      throw new DeveloperError("p0 is required.");
    }
    if (!defined(p1)) {
      throw new DeveloperError("p1 is required.");
    }
    if (!defined(p2)) {
      throw new DeveloperError("p2 is required.");
    }
    //>>includeEnd('debug');

    var ray = scratchLineSegmentTriangleRay;
    Cartesian3.clone(v0, ray.origin);
    Cartesian3.subtract(v1, v0, ray.direction);
    Cartesian3.normalize(ray.direction, ray.direction);

    var t = IntersectionTests.rayTriangleParametric(
      ray,
      p0,
      p1,
      p2,
      cullBackFaces
    );
    if (!defined(t) || t < 0.0 || t > Cartesian3.distance(v0, v1)) {
      return undefined;
    }

    if (!defined(result)) {
      result = new Cartesian3();
    }

    Cartesian3.multiplyByScalar(ray.direction, t, result);
    return Cartesian3.add(ray.origin, result, result);
  };

  function solveQuadratic(a, b, c, result) {
    var det = b * b - 4.0 * a * c;
    if (det < 0.0) {
      return undefined;
    } else if (det > 0.0) {
      var denom = 1.0 / (2.0 * a);
      var disc = Math.sqrt(det);
      var root0 = (-b + disc) * denom;
      var root1 = (-b - disc) * denom;

      if (root0 < root1) {
        result.root0 = root0;
        result.root1 = root1;
      } else {
        result.root0 = root1;
        result.root1 = root0;
      }

      return result;
    }

    var root = -b / (2.0 * a);
    if (root === 0.0) {
      return undefined;
    }

    result.root0 = result.root1 = root;
    return result;
  }

  var raySphereRoots = {
    root0: 0.0,
    root1: 0.0,
  };

  function raySphere(ray, sphere, result) {
    if (!defined(result)) {
      result = new Interval();
    }

    var origin = ray.origin;
    var direction = ray.direction;

    var center = sphere.center;
    var radiusSquared = sphere.radius * sphere.radius;

    var diff = Cartesian3.subtract(origin, center, scratchPVec);

    var a = Cartesian3.dot(direction, direction);
    var b = 2.0 * Cartesian3.dot(direction, diff);
    var c = Cartesian3.magnitudeSquared(diff) - radiusSquared;

    var roots = solveQuadratic(a, b, c, raySphereRoots);
    if (!defined(roots)) {
      return undefined;
    }

    result.start = roots.root0;
    result.stop = roots.root1;
    return result;
  }

  /**
   * Computes the intersection points of a ray with a sphere.
   * @memberof IntersectionTests
   *
   * @param {Ray} ray The ray.
   * @param {BoundingSphere} sphere The sphere.
   * @param {Interval} [result] The result onto which to store the result.
   * @returns {Interval} The interval containing scalar points along the ray or undefined if there are no intersections.
   */
  IntersectionTests.raySphere = function (ray, sphere, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(ray)) {
      throw new DeveloperError("ray is required.");
    }
    if (!defined(sphere)) {
      throw new DeveloperError("sphere is required.");
    }
    //>>includeEnd('debug');

    result = raySphere(ray, sphere, result);
    if (!defined(result) || result.stop < 0.0) {
      return undefined;
    }

    result.start = Math.max(result.start, 0.0);
    return result;
  };

  var scratchLineSegmentRay = new Ray();

  /**
   * Computes the intersection points of a line segment with a sphere.
   * @memberof IntersectionTests
   *
   * @param {Cartesian3} p0 An end point of the line segment.
   * @param {Cartesian3} p1 The other end point of the line segment.
   * @param {BoundingSphere} sphere The sphere.
   * @param {Interval} [result] The result onto which to store the result.
   * @returns {Interval} The interval containing scalar points along the ray or undefined if there are no intersections.
   */
  IntersectionTests.lineSegmentSphere = function (p0, p1, sphere, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(p0)) {
      throw new DeveloperError("p0 is required.");
    }
    if (!defined(p1)) {
      throw new DeveloperError("p1 is required.");
    }
    if (!defined(sphere)) {
      throw new DeveloperError("sphere is required.");
    }
    //>>includeEnd('debug');

    var ray = scratchLineSegmentRay;
    Cartesian3.clone(p0, ray.origin);
    var direction = Cartesian3.subtract(p1, p0, ray.direction);

    var maxT = Cartesian3.magnitude(direction);
    Cartesian3.normalize(direction, direction);

    result = raySphere(ray, sphere, result);
    if (!defined(result) || result.stop < 0.0 || result.start > maxT) {
      return undefined;
    }

    result.start = Math.max(result.start, 0.0);
    result.stop = Math.min(result.stop, maxT);
    return result;
  };

  var scratchQ = new Cartesian3();
  var scratchW = new Cartesian3();

  /**
   * Computes the intersection points of a ray with an ellipsoid.
   *
   * @param {Ray} ray The ray.
   * @param {Ellipsoid} ellipsoid The ellipsoid.
   * @returns {Interval} The interval containing scalar points along the ray or undefined if there are no intersections.
   */
  IntersectionTests.rayEllipsoid = function (ray, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(ray)) {
      throw new DeveloperError("ray is required.");
    }
    if (!defined(ellipsoid)) {
      throw new DeveloperError("ellipsoid is required.");
    }
    //>>includeEnd('debug');

    var inverseRadii = ellipsoid.oneOverRadii;
    var q = Cartesian3.multiplyComponents(inverseRadii, ray.origin, scratchQ);
    var w = Cartesian3.multiplyComponents(inverseRadii, ray.direction, scratchW);

    var q2 = Cartesian3.magnitudeSquared(q);
    var qw = Cartesian3.dot(q, w);

    var difference, w2, product, discriminant, temp;

    if (q2 > 1.0) {
      // Outside ellipsoid.
      if (qw >= 0.0) {
        // Looking outward or tangent (0 intersections).
        return undefined;
      }

      // qw < 0.0.
      var qw2 = qw * qw;
      difference = q2 - 1.0; // Positively valued.
      w2 = Cartesian3.magnitudeSquared(w);
      product = w2 * difference;

      if (qw2 < product) {
        // Imaginary roots (0 intersections).
        return undefined;
      } else if (qw2 > product) {
        // Distinct roots (2 intersections).
        discriminant = qw * qw - product;
        temp = -qw + Math.sqrt(discriminant); // Avoid cancellation.
        var root0 = temp / w2;
        var root1 = difference / temp;
        if (root0 < root1) {
          return new Interval(root0, root1);
        }

        return {
          start: root1,
          stop: root0,
        };
      }
      // qw2 == product.  Repeated roots (2 intersections).
      var root = Math.sqrt(difference / w2);
      return new Interval(root, root);
    } else if (q2 < 1.0) {
      // Inside ellipsoid (2 intersections).
      difference = q2 - 1.0; // Negatively valued.
      w2 = Cartesian3.magnitudeSquared(w);
      product = w2 * difference; // Negatively valued.

      discriminant = qw * qw - product;
      temp = -qw + Math.sqrt(discriminant); // Positively valued.
      return new Interval(0.0, temp / w2);
    }
    // q2 == 1.0. On ellipsoid.
    if (qw < 0.0) {
      // Looking inward.
      w2 = Cartesian3.magnitudeSquared(w);
      return new Interval(0.0, -qw / w2);
    }

    // qw >= 0.0.  Looking outward or tangent.
    return undefined;
  };

  function addWithCancellationCheck$1(left, right, tolerance) {
    var difference = left + right;
    if (
      CesiumMath.sign(left) !== CesiumMath.sign(right) &&
      Math.abs(difference / Math.max(Math.abs(left), Math.abs(right))) < tolerance
    ) {
      return 0.0;
    }

    return difference;
  }

  function quadraticVectorExpression(A, b, c, x, w) {
    var xSquared = x * x;
    var wSquared = w * w;

    var l2 = (A[Matrix3.COLUMN1ROW1] - A[Matrix3.COLUMN2ROW2]) * wSquared;
    var l1 =
      w *
      (x *
        addWithCancellationCheck$1(
          A[Matrix3.COLUMN1ROW0],
          A[Matrix3.COLUMN0ROW1],
          CesiumMath.EPSILON15
        ) +
        b.y);
    var l0 =
      A[Matrix3.COLUMN0ROW0] * xSquared +
      A[Matrix3.COLUMN2ROW2] * wSquared +
      x * b.x +
      c;

    var r1 =
      wSquared *
      addWithCancellationCheck$1(
        A[Matrix3.COLUMN2ROW1],
        A[Matrix3.COLUMN1ROW2],
        CesiumMath.EPSILON15
      );
    var r0 =
      w *
      (x *
        addWithCancellationCheck$1(A[Matrix3.COLUMN2ROW0], A[Matrix3.COLUMN0ROW2]) +
        b.z);

    var cosines;
    var solutions = [];
    if (r0 === 0.0 && r1 === 0.0) {
      cosines = QuadraticRealPolynomial.computeRealRoots(l2, l1, l0);
      if (cosines.length === 0) {
        return solutions;
      }

      var cosine0 = cosines[0];
      var sine0 = Math.sqrt(Math.max(1.0 - cosine0 * cosine0, 0.0));
      solutions.push(new Cartesian3(x, w * cosine0, w * -sine0));
      solutions.push(new Cartesian3(x, w * cosine0, w * sine0));

      if (cosines.length === 2) {
        var cosine1 = cosines[1];
        var sine1 = Math.sqrt(Math.max(1.0 - cosine1 * cosine1, 0.0));
        solutions.push(new Cartesian3(x, w * cosine1, w * -sine1));
        solutions.push(new Cartesian3(x, w * cosine1, w * sine1));
      }

      return solutions;
    }

    var r0Squared = r0 * r0;
    var r1Squared = r1 * r1;
    var l2Squared = l2 * l2;
    var r0r1 = r0 * r1;

    var c4 = l2Squared + r1Squared;
    var c3 = 2.0 * (l1 * l2 + r0r1);
    var c2 = 2.0 * l0 * l2 + l1 * l1 - r1Squared + r0Squared;
    var c1 = 2.0 * (l0 * l1 - r0r1);
    var c0 = l0 * l0 - r0Squared;

    if (c4 === 0.0 && c3 === 0.0 && c2 === 0.0 && c1 === 0.0) {
      return solutions;
    }

    cosines = QuarticRealPolynomial.computeRealRoots(c4, c3, c2, c1, c0);
    var length = cosines.length;
    if (length === 0) {
      return solutions;
    }

    for (var i = 0; i < length; ++i) {
      var cosine = cosines[i];
      var cosineSquared = cosine * cosine;
      var sineSquared = Math.max(1.0 - cosineSquared, 0.0);
      var sine = Math.sqrt(sineSquared);

      //var left = l2 * cosineSquared + l1 * cosine + l0;
      var left;
      if (CesiumMath.sign(l2) === CesiumMath.sign(l0)) {
        left = addWithCancellationCheck$1(
          l2 * cosineSquared + l0,
          l1 * cosine,
          CesiumMath.EPSILON12
        );
      } else if (CesiumMath.sign(l0) === CesiumMath.sign(l1 * cosine)) {
        left = addWithCancellationCheck$1(
          l2 * cosineSquared,
          l1 * cosine + l0,
          CesiumMath.EPSILON12
        );
      } else {
        left = addWithCancellationCheck$1(
          l2 * cosineSquared + l1 * cosine,
          l0,
          CesiumMath.EPSILON12
        );
      }

      var right = addWithCancellationCheck$1(r1 * cosine, r0, CesiumMath.EPSILON15);
      var product = left * right;

      if (product < 0.0) {
        solutions.push(new Cartesian3(x, w * cosine, w * sine));
      } else if (product > 0.0) {
        solutions.push(new Cartesian3(x, w * cosine, w * -sine));
      } else if (sine !== 0.0) {
        solutions.push(new Cartesian3(x, w * cosine, w * -sine));
        solutions.push(new Cartesian3(x, w * cosine, w * sine));
        ++i;
      } else {
        solutions.push(new Cartesian3(x, w * cosine, w * sine));
      }
    }

    return solutions;
  }

  var firstAxisScratch = new Cartesian3();
  var secondAxisScratch = new Cartesian3();
  var thirdAxisScratch = new Cartesian3();
  var referenceScratch = new Cartesian3();
  var bCart = new Cartesian3();
  var bScratch = new Matrix3();
  var btScratch = new Matrix3();
  var diScratch = new Matrix3();
  var dScratch = new Matrix3();
  var cScratch = new Matrix3();
  var tempMatrix = new Matrix3();
  var aScratch = new Matrix3();
  var sScratch = new Cartesian3();
  var closestScratch = new Cartesian3();
  var surfPointScratch = new Cartographic();

  /**
   * Provides the point along the ray which is nearest to the ellipsoid.
   *
   * @param {Ray} ray The ray.
   * @param {Ellipsoid} ellipsoid The ellipsoid.
   * @returns {Cartesian3} The nearest planetodetic point on the ray.
   */
  IntersectionTests.grazingAltitudeLocation = function (ray, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(ray)) {
      throw new DeveloperError("ray is required.");
    }
    if (!defined(ellipsoid)) {
      throw new DeveloperError("ellipsoid is required.");
    }
    //>>includeEnd('debug');

    var position = ray.origin;
    var direction = ray.direction;

    if (!Cartesian3.equals(position, Cartesian3.ZERO)) {
      var normal = ellipsoid.geodeticSurfaceNormal(position, firstAxisScratch);
      if (Cartesian3.dot(direction, normal) >= 0.0) {
        // The location provided is the closest point in altitude
        return position;
      }
    }

    var intersects = defined(this.rayEllipsoid(ray, ellipsoid));

    // Compute the scaled direction vector.
    var f = ellipsoid.transformPositionToScaledSpace(direction, firstAxisScratch);

    // Constructs a basis from the unit scaled direction vector. Construct its rotation and transpose.
    var firstAxis = Cartesian3.normalize(f, f);
    var reference = Cartesian3.mostOrthogonalAxis(f, referenceScratch);
    var secondAxis = Cartesian3.normalize(
      Cartesian3.cross(reference, firstAxis, secondAxisScratch),
      secondAxisScratch
    );
    var thirdAxis = Cartesian3.normalize(
      Cartesian3.cross(firstAxis, secondAxis, thirdAxisScratch),
      thirdAxisScratch
    );
    var B = bScratch;
    B[0] = firstAxis.x;
    B[1] = firstAxis.y;
    B[2] = firstAxis.z;
    B[3] = secondAxis.x;
    B[4] = secondAxis.y;
    B[5] = secondAxis.z;
    B[6] = thirdAxis.x;
    B[7] = thirdAxis.y;
    B[8] = thirdAxis.z;

    var B_T = Matrix3.transpose(B, btScratch);

    // Get the scaling matrix and its inverse.
    var D_I = Matrix3.fromScale(ellipsoid.radii, diScratch);
    var D = Matrix3.fromScale(ellipsoid.oneOverRadii, dScratch);

    var C = cScratch;
    C[0] = 0.0;
    C[1] = -direction.z;
    C[2] = direction.y;
    C[3] = direction.z;
    C[4] = 0.0;
    C[5] = -direction.x;
    C[6] = -direction.y;
    C[7] = direction.x;
    C[8] = 0.0;

    var temp = Matrix3.multiply(
      Matrix3.multiply(B_T, D, tempMatrix),
      C,
      tempMatrix
    );
    var A = Matrix3.multiply(Matrix3.multiply(temp, D_I, aScratch), B, aScratch);
    var b = Matrix3.multiplyByVector(temp, position, bCart);

    // Solve for the solutions to the expression in standard form:
    var solutions = quadraticVectorExpression(
      A,
      Cartesian3.negate(b, firstAxisScratch),
      0.0,
      0.0,
      1.0
    );

    var s;
    var altitude;
    var length = solutions.length;
    if (length > 0) {
      var closest = Cartesian3.clone(Cartesian3.ZERO, closestScratch);
      var maximumValue = Number.NEGATIVE_INFINITY;

      for (var i = 0; i < length; ++i) {
        s = Matrix3.multiplyByVector(
          D_I,
          Matrix3.multiplyByVector(B, solutions[i], sScratch),
          sScratch
        );
        var v = Cartesian3.normalize(
          Cartesian3.subtract(s, position, referenceScratch),
          referenceScratch
        );
        var dotProduct = Cartesian3.dot(v, direction);

        if (dotProduct > maximumValue) {
          maximumValue = dotProduct;
          closest = Cartesian3.clone(s, closest);
        }
      }

      var surfacePoint = ellipsoid.cartesianToCartographic(
        closest,
        surfPointScratch
      );
      maximumValue = CesiumMath.clamp(maximumValue, 0.0, 1.0);
      altitude =
        Cartesian3.magnitude(
          Cartesian3.subtract(closest, position, referenceScratch)
        ) * Math.sqrt(1.0 - maximumValue * maximumValue);
      altitude = intersects ? -altitude : altitude;
      surfacePoint.height = altitude;
      return ellipsoid.cartographicToCartesian(surfacePoint, new Cartesian3());
    }

    return undefined;
  };

  var lineSegmentPlaneDifference = new Cartesian3();

  /**
   * Computes the intersection of a line segment and a plane.
   *
   * @param {Cartesian3} endPoint0 An end point of the line segment.
   * @param {Cartesian3} endPoint1 The other end point of the line segment.
   * @param {Plane} plane The plane.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The intersection point or undefined if there is no intersection.
   *
   * @example
   * var origin = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
   * var normal = ellipsoid.geodeticSurfaceNormal(origin);
   * var plane = Cesium.Plane.fromPointNormal(origin, normal);
   *
   * var p0 = new Cesium.Cartesian3(...);
   * var p1 = new Cesium.Cartesian3(...);
   *
   * // find the intersection of the line segment from p0 to p1 and the tangent plane at origin.
   * var intersection = Cesium.IntersectionTests.lineSegmentPlane(p0, p1, plane);
   */
  IntersectionTests.lineSegmentPlane = function (
    endPoint0,
    endPoint1,
    plane,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(endPoint0)) {
      throw new DeveloperError("endPoint0 is required.");
    }
    if (!defined(endPoint1)) {
      throw new DeveloperError("endPoint1 is required.");
    }
    if (!defined(plane)) {
      throw new DeveloperError("plane is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    var difference = Cartesian3.subtract(
      endPoint1,
      endPoint0,
      lineSegmentPlaneDifference
    );
    var normal = plane.normal;
    var nDotDiff = Cartesian3.dot(normal, difference);

    // check if the segment and plane are parallel
    if (Math.abs(nDotDiff) < CesiumMath.EPSILON6) {
      return undefined;
    }

    var nDotP0 = Cartesian3.dot(normal, endPoint0);
    var t = -(plane.distance + nDotP0) / nDotDiff;

    // intersection only if t is in [0, 1]
    if (t < 0.0 || t > 1.0) {
      return undefined;
    }

    // intersection is endPoint0 + t * (endPoint1 - endPoint0)
    Cartesian3.multiplyByScalar(difference, t, result);
    Cartesian3.add(endPoint0, result, result);
    return result;
  };

  /**
   * Computes the intersection of a triangle and a plane
   *
   * @param {Cartesian3} p0 First point of the triangle
   * @param {Cartesian3} p1 Second point of the triangle
   * @param {Cartesian3} p2 Third point of the triangle
   * @param {Plane} plane Intersection plane
   * @returns {Object} An object with properties <code>positions</code> and <code>indices</code>, which are arrays that represent three triangles that do not cross the plane. (Undefined if no intersection exists)
   *
   * @example
   * var origin = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
   * var normal = ellipsoid.geodeticSurfaceNormal(origin);
   * var plane = Cesium.Plane.fromPointNormal(origin, normal);
   *
   * var p0 = new Cesium.Cartesian3(...);
   * var p1 = new Cesium.Cartesian3(...);
   * var p2 = new Cesium.Cartesian3(...);
   *
   * // convert the triangle composed of points (p0, p1, p2) to three triangles that don't cross the plane
   * var triangles = Cesium.IntersectionTests.trianglePlaneIntersection(p0, p1, p2, plane);
   */
  IntersectionTests.trianglePlaneIntersection = function (p0, p1, p2, plane) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(p0) || !defined(p1) || !defined(p2) || !defined(plane)) {
      throw new DeveloperError("p0, p1, p2, and plane are required.");
    }
    //>>includeEnd('debug');

    var planeNormal = plane.normal;
    var planeD = plane.distance;
    var p0Behind = Cartesian3.dot(planeNormal, p0) + planeD < 0.0;
    var p1Behind = Cartesian3.dot(planeNormal, p1) + planeD < 0.0;
    var p2Behind = Cartesian3.dot(planeNormal, p2) + planeD < 0.0;
    // Given these dots products, the calls to lineSegmentPlaneIntersection
    // always have defined results.

    var numBehind = 0;
    numBehind += p0Behind ? 1 : 0;
    numBehind += p1Behind ? 1 : 0;
    numBehind += p2Behind ? 1 : 0;

    var u1, u2;
    if (numBehind === 1 || numBehind === 2) {
      u1 = new Cartesian3();
      u2 = new Cartesian3();
    }

    if (numBehind === 1) {
      if (p0Behind) {
        IntersectionTests.lineSegmentPlane(p0, p1, plane, u1);
        IntersectionTests.lineSegmentPlane(p0, p2, plane, u2);

        return {
          positions: [p0, p1, p2, u1, u2],
          indices: [
            // Behind
            0,
            3,
            4,

            // In front
            1,
            2,
            4,
            1,
            4,
            3,
          ],
        };
      } else if (p1Behind) {
        IntersectionTests.lineSegmentPlane(p1, p2, plane, u1);
        IntersectionTests.lineSegmentPlane(p1, p0, plane, u2);

        return {
          positions: [p0, p1, p2, u1, u2],
          indices: [
            // Behind
            1,
            3,
            4,

            // In front
            2,
            0,
            4,
            2,
            4,
            3,
          ],
        };
      } else if (p2Behind) {
        IntersectionTests.lineSegmentPlane(p2, p0, plane, u1);
        IntersectionTests.lineSegmentPlane(p2, p1, plane, u2);

        return {
          positions: [p0, p1, p2, u1, u2],
          indices: [
            // Behind
            2,
            3,
            4,

            // In front
            0,
            1,
            4,
            0,
            4,
            3,
          ],
        };
      }
    } else if (numBehind === 2) {
      if (!p0Behind) {
        IntersectionTests.lineSegmentPlane(p1, p0, plane, u1);
        IntersectionTests.lineSegmentPlane(p2, p0, plane, u2);

        return {
          positions: [p0, p1, p2, u1, u2],
          indices: [
            // Behind
            1,
            2,
            4,
            1,
            4,
            3,

            // In front
            0,
            3,
            4,
          ],
        };
      } else if (!p1Behind) {
        IntersectionTests.lineSegmentPlane(p2, p1, plane, u1);
        IntersectionTests.lineSegmentPlane(p0, p1, plane, u2);

        return {
          positions: [p0, p1, p2, u1, u2],
          indices: [
            // Behind
            2,
            0,
            4,
            2,
            4,
            3,

            // In front
            1,
            3,
            4,
          ],
        };
      } else if (!p2Behind) {
        IntersectionTests.lineSegmentPlane(p0, p2, plane, u1);
        IntersectionTests.lineSegmentPlane(p1, p2, plane, u2);

        return {
          positions: [p0, p1, p2, u1, u2],
          indices: [
            // Behind
            0,
            1,
            4,
            0,
            4,
            3,

            // In front
            2,
            3,
            4,
          ],
        };
      }
    }

    // if numBehind is 3, the triangle is completely behind the plane;
    // otherwise, it is completely in front (numBehind is 0).
    return undefined;
  };

  /**
   * A plane in Hessian Normal Form defined by
   * <pre>
   * ax + by + cz + d = 0
   * </pre>
   * where (a, b, c) is the plane's <code>normal</code>, d is the signed
   * <code>distance</code> to the plane, and (x, y, z) is any point on
   * the plane.
   *
   * @alias Plane
   * @constructor
   *
   * @param {Cartesian3} normal The plane's normal (normalized).
   * @param {Number} distance The shortest distance from the origin to the plane.  The sign of
   * <code>distance</code> determines which side of the plane the origin
   * is on.  If <code>distance</code> is positive, the origin is in the half-space
   * in the direction of the normal; if negative, the origin is in the half-space
   * opposite to the normal; if zero, the plane passes through the origin.
   *
   * @example
   * // The plane x=0
   * var plane = new Cesium.Plane(Cesium.Cartesian3.UNIT_X, 0.0);
   *
   * @exception {DeveloperError} Normal must be normalized
   */
  function Plane(normal, distance) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("normal", normal);
    if (
      !CesiumMath.equalsEpsilon(
        Cartesian3.magnitude(normal),
        1.0,
        CesiumMath.EPSILON6
      )
    ) {
      throw new DeveloperError("normal must be normalized.");
    }
    Check.typeOf.number("distance", distance);
    //>>includeEnd('debug');

    /**
     * The plane's normal.
     *
     * @type {Cartesian3}
     */
    this.normal = Cartesian3.clone(normal);

    /**
     * The shortest distance from the origin to the plane.  The sign of
     * <code>distance</code> determines which side of the plane the origin
     * is on.  If <code>distance</code> is positive, the origin is in the half-space
     * in the direction of the normal; if negative, the origin is in the half-space
     * opposite to the normal; if zero, the plane passes through the origin.
     *
     * @type {Number}
     */
    this.distance = distance;
  }

  /**
   * Creates a plane from a normal and a point on the plane.
   *
   * @param {Cartesian3} point The point on the plane.
   * @param {Cartesian3} normal The plane's normal (normalized).
   * @param {Plane} [result] The object onto which to store the result.
   * @returns {Plane} A new plane instance or the modified result parameter.
   *
   * @example
   * var point = Cesium.Cartesian3.fromDegrees(-72.0, 40.0);
   * var normal = ellipsoid.geodeticSurfaceNormal(point);
   * var tangentPlane = Cesium.Plane.fromPointNormal(point, normal);
   *
   * @exception {DeveloperError} Normal must be normalized
   */
  Plane.fromPointNormal = function (point, normal, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("point", point);
    Check.typeOf.object("normal", normal);
    if (
      !CesiumMath.equalsEpsilon(
        Cartesian3.magnitude(normal),
        1.0,
        CesiumMath.EPSILON6
      )
    ) {
      throw new DeveloperError("normal must be normalized.");
    }
    //>>includeEnd('debug');

    var distance = -Cartesian3.dot(normal, point);

    if (!defined(result)) {
      return new Plane(normal, distance);
    }

    Cartesian3.clone(normal, result.normal);
    result.distance = distance;
    return result;
  };

  var scratchNormal = new Cartesian3();
  /**
   * Creates a plane from the general equation
   *
   * @param {Cartesian4} coefficients The plane's normal (normalized).
   * @param {Plane} [result] The object onto which to store the result.
   * @returns {Plane} A new plane instance or the modified result parameter.
   *
   * @exception {DeveloperError} Normal must be normalized
   */
  Plane.fromCartesian4 = function (coefficients, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("coefficients", coefficients);
    //>>includeEnd('debug');

    var normal = Cartesian3.fromCartesian4(coefficients, scratchNormal);
    var distance = coefficients.w;

    //>>includeStart('debug', pragmas.debug);
    if (
      !CesiumMath.equalsEpsilon(
        Cartesian3.magnitude(normal),
        1.0,
        CesiumMath.EPSILON6
      )
    ) {
      throw new DeveloperError("normal must be normalized.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Plane(normal, distance);
    }
    Cartesian3.clone(normal, result.normal);
    result.distance = distance;
    return result;
  };

  /**
   * Computes the signed shortest distance of a point to a plane.
   * The sign of the distance determines which side of the plane the point
   * is on.  If the distance is positive, the point is in the half-space
   * in the direction of the normal; if negative, the point is in the half-space
   * opposite to the normal; if zero, the plane passes through the point.
   *
   * @param {Plane} plane The plane.
   * @param {Cartesian3} point The point.
   * @returns {Number} The signed shortest distance of the point to the plane.
   */
  Plane.getPointDistance = function (plane, point) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("plane", plane);
    Check.typeOf.object("point", point);
    //>>includeEnd('debug');

    return Cartesian3.dot(plane.normal, point) + plane.distance;
  };

  var scratchCartesian$1 = new Cartesian3();
  /**
   * Projects a point onto the plane.
   * @param {Plane} plane The plane to project the point onto
   * @param {Cartesian3} point The point to project onto the plane
   * @param {Cartesian3} [result] The result point.  If undefined, a new Cartesian3 will be created.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   */
  Plane.projectPointOntoPlane = function (plane, point, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("plane", plane);
    Check.typeOf.object("point", point);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    // projectedPoint = point - (normal.point + scale) * normal
    var pointDistance = Plane.getPointDistance(plane, point);
    var scaledNormal = Cartesian3.multiplyByScalar(
      plane.normal,
      pointDistance,
      scratchCartesian$1
    );

    return Cartesian3.subtract(point, scaledNormal, result);
  };

  var scratchPosition = new Cartesian3();
  /**
   * Transforms the plane by the given transformation matrix.
   *
   * @param {Plane} plane The plane.
   * @param {Matrix4} transform The transformation matrix.
   * @param {Plane} [result] The object into which to store the result.
   * @returns {Plane} The plane transformed by the given transformation matrix.
   */
  Plane.transform = function (plane, transform, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("plane", plane);
    Check.typeOf.object("transform", transform);
    //>>includeEnd('debug');

    Matrix4.multiplyByPointAsVector(transform, plane.normal, scratchNormal);
    Cartesian3.normalize(scratchNormal, scratchNormal);

    Cartesian3.multiplyByScalar(plane.normal, -plane.distance, scratchPosition);
    Matrix4.multiplyByPoint(transform, scratchPosition, scratchPosition);

    return Plane.fromPointNormal(scratchPosition, scratchNormal, result);
  };

  /**
   * Duplicates a Plane instance.
   *
   * @param {Plane} plane The plane to duplicate.
   * @param {Plane} [result] The object onto which to store the result.
   * @returns {Plane} The modified result parameter or a new Plane instance if one was not provided.
   */
  Plane.clone = function (plane, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("plane", plane);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Plane(plane.normal, plane.distance);
    }

    Cartesian3.clone(plane.normal, result.normal);
    result.distance = plane.distance;

    return result;
  };

  /**
   * Compares the provided Planes by normal and distance and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Plane} left The first plane.
   * @param {Plane} right The second plane.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Plane.equals = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    return (
      left.distance === right.distance &&
      Cartesian3.equals(left.normal, right.normal)
    );
  };

  /**
   * A constant initialized to the XY plane passing through the origin, with normal in positive Z.
   *
   * @type {Plane}
   * @constant
   */
  Plane.ORIGIN_XY_PLANE = Object.freeze(new Plane(Cartesian3.UNIT_Z, 0.0));

  /**
   * A constant initialized to the YZ plane passing through the origin, with normal in positive X.
   *
   * @type {Plane}
   * @constant
   */
  Plane.ORIGIN_YZ_PLANE = Object.freeze(new Plane(Cartesian3.UNIT_X, 0.0));

  /**
   * A constant initialized to the ZX plane passing through the origin, with normal in positive Y.
   *
   * @type {Plane}
   * @constant
   */
  Plane.ORIGIN_ZX_PLANE = Object.freeze(new Plane(Cartesian3.UNIT_Y, 0.0));

  /**
   * Finds an item in a sorted array.
   *
   * @function
   * @param {Array} array The sorted array to search.
   * @param {*} itemToFind The item to find in the array.
   * @param {binarySearchComparator} comparator The function to use to compare the item to
   *        elements in the array.
   * @returns {Number} The index of <code>itemToFind</code> in the array, if it exists.  If <code>itemToFind</code>
   *        does not exist, the return value is a negative number which is the bitwise complement (~)
   *        of the index before which the itemToFind should be inserted in order to maintain the
   *        sorted order of the array.
   *
   * @example
   * // Create a comparator function to search through an array of numbers.
   * function comparator(a, b) {
   *     return a - b;
   * };
   * var numbers = [0, 2, 4, 6, 8];
   * var index = Cesium.binarySearch(numbers, 6, comparator); // 3
   */
  function binarySearch(array, itemToFind, comparator) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    Check.defined("itemToFind", itemToFind);
    Check.defined("comparator", comparator);
    //>>includeEnd('debug');

    var low = 0;
    var high = array.length - 1;
    var i;
    var comparison;

    while (low <= high) {
      i = ~~((low + high) / 2);
      comparison = comparator(array[i], itemToFind);
      if (comparison < 0) {
        low = i + 1;
        continue;
      }
      if (comparison > 0) {
        high = i - 1;
        continue;
      }
      return i;
    }
    return ~(high + 1);
  }

  /**
   * A set of Earth Orientation Parameters (EOP) sampled at a time.
   *
   * @alias EarthOrientationParametersSample
   * @constructor
   *
   * @param {Number} xPoleWander The pole wander about the X axis, in radians.
   * @param {Number} yPoleWander The pole wander about the Y axis, in radians.
   * @param {Number} xPoleOffset The offset to the Celestial Intermediate Pole (CIP) about the X axis, in radians.
   * @param {Number} yPoleOffset The offset to the Celestial Intermediate Pole (CIP) about the Y axis, in radians.
   * @param {Number} ut1MinusUtc The difference in time standards, UT1 - UTC, in seconds.
   *
   * @private
   */
  function EarthOrientationParametersSample(
    xPoleWander,
    yPoleWander,
    xPoleOffset,
    yPoleOffset,
    ut1MinusUtc
  ) {
    /**
     * The pole wander about the X axis, in radians.
     * @type {Number}
     */
    this.xPoleWander = xPoleWander;

    /**
     * The pole wander about the Y axis, in radians.
     * @type {Number}
     */
    this.yPoleWander = yPoleWander;

    /**
     * The offset to the Celestial Intermediate Pole (CIP) about the X axis, in radians.
     * @type {Number}
     */
    this.xPoleOffset = xPoleOffset;

    /**
     * The offset to the Celestial Intermediate Pole (CIP) about the Y axis, in radians.
     * @type {Number}
     */
    this.yPoleOffset = yPoleOffset;

    /**
     * The difference in time standards, UT1 - UTC, in seconds.
     * @type {Number}
     */
    this.ut1MinusUtc = ut1MinusUtc;
  }

  /**
  @license
  sprintf.js from the php.js project - https://github.com/kvz/phpjs
  Directly from https://github.com/kvz/phpjs/blob/master/functions/strings/sprintf.js

  php.js is copyright 2012 Kevin van Zonneveld.

  Portions copyright Brett Zamir (http://brett-zamir.me), Kevin van Zonneveld
  (http://kevin.vanzonneveld.net), Onno Marsman, Theriault, Michael White
  (http://getsprink.com), Waldo Malqui Silva, Paulo Freitas, Jack, Jonas
  Raoni Soares Silva (http://www.jsfromhell.com), Philip Peterson, Legaev
  Andrey, Ates Goral (http://magnetiq.com), Alex, Ratheous, Martijn Wieringa,
  Rafa? Kukawski (http://blog.kukawski.pl), lmeyrick
  (https://sourceforge.net/projects/bcmath-js/), Nate, Philippe Baumann,
  Enrique Gonzalez, Webtoolkit.info (http://www.webtoolkit.info/), Carlos R.
  L. Rodrigues (http://www.jsfromhell.com), Ash Searle
  (http://hexmen.com/blog/), Jani Hartikainen, travc, Ole Vrijenhoek,
  Erkekjetter, Michael Grier, Rafa? Kukawski (http://kukawski.pl), Johnny
  Mast (http://www.phpvrouwen.nl), T.Wild, d3x,
  http://stackoverflow.com/questions/57803/how-to-convert-decimal-to-hex-in-javascript,
  Rafa? Kukawski (http://blog.kukawski.pl/), stag019, pilus, WebDevHobo
  (http://webdevhobo.blogspot.com/), marrtins, GeekFG
  (http://geekfg.blogspot.com), Andrea Giammarchi
  (http://webreflection.blogspot.com), Arpad Ray (mailto:arpad@php.net),
  gorthaur, Paul Smith, Tim de Koning (http://www.kingsquare.nl), Joris, Oleg
  Eremeev, Steve Hilder, majak, gettimeofday, KELAN, Josh Fraser
  (http://onlineaspect.com/2007/06/08/auto-detect-a-time-zone-with-javascript/),
  Marc Palau, Martin
  (http://www.erlenwiese.de/), Breaking Par Consulting Inc
  (http://www.breakingpar.com/bkp/home.nsf/0/87256B280015193F87256CFB006C45F7),
  Chris, Mirek Slugen, saulius, Alfonso Jimenez
  (http://www.alfonsojimenez.com), Diplom@t (http://difane.com/), felix,
  Mailfaker (http://www.weedem.fr/), Tyler Akins (http://rumkin.com), Caio
  Ariede (http://caioariede.com), Robin, Kankrelune
  (http://www.webfaktory.info/), Karol Kowalski, Imgen Tata
  (http://www.myipdf.com/), mdsjack (http://www.mdsjack.bo.it), Dreamer,
  Felix Geisendoerfer (http://www.debuggable.com/felix), Lars Fischer, AJ,
  David, Aman Gupta, Michael White, Public Domain
  (http://www.json.org/json2.js), Steven Levithan
  (http://blog.stevenlevithan.com), Sakimori, Pellentesque Malesuada,
  Thunder.m, Dj (http://phpjs.org/functions/htmlentities:425#comment_134018),
  Steve Clay, David James, Francois, class_exists, nobbler, T. Wild, Itsacon
  (http://www.itsacon.net/), date, Ole Vrijenhoek (http://www.nervous.nl/),
  Fox, Raphael (Ao RUDLER), Marco, noname, Mateusz "loonquawl" Zalega, Frank
  Forte, Arno, ger, mktime, john (http://www.jd-tech.net), Nick Kolosov
  (http://sammy.ru), marc andreu, Scott Cariss, Douglas Crockford
  (http://javascript.crockford.com), madipta, Slawomir Kaniecki,
  ReverseSyntax, Nathan, Alex Wilson, kenneth, Bayron Guevara, Adam Wallner
  (http://web2.bitbaro.hu/), paulo kuong, jmweb, Lincoln Ramsay, djmix,
  Pyerre, Jon Hohle, Thiago Mata (http://thiagomata.blog.com), lmeyrick
  (https://sourceforge.net/projects/bcmath-js/this.), Linuxworld, duncan,
  Gilbert, Sanjoy Roy, Shingo, sankai, Oskar Larsson H?gfeldt
  (http://oskar-lh.name/), Denny Wardhana, 0m3r, Everlasto, Subhasis Deb,
  josh, jd, Pier Paolo Ramon (http://www.mastersoup.com/), P, merabi, Soren
  Hansen, Eugene Bulkin (http://doubleaw.com/), Der Simon
  (http://innerdom.sourceforge.net/), echo is bad, Ozh, XoraX
  (http://www.xorax.info), EdorFaus, JB, J A R, Marc Jansen, Francesco, LH,
  Stoyan Kyosev (http://www.svest.org/), nord_ua, omid
  (http://phpjs.org/functions/380:380#comment_137122), Brad Touesnard, MeEtc
  (http://yass.meetcweb.com), Peter-Paul Koch
  (http://www.quirksmode.org/js/beat.html), Olivier Louvignes
  (http://mg-crea.com/), T0bsn, Tim Wiel, Bryan Elliott, Jalal Berrami,
  Martin, JT, David Randall, Thomas Beaucourt (http://www.webapp.fr), taith,
  vlado houba, Pierre-Luc Paour, Kristof Coomans (SCK-CEN Belgian Nucleair
  Research Centre), Martin Pool, Kirk Strobeck, Rick Waldron, Brant Messenger
  (http://www.brantmessenger.com/), Devan Penner-Woelk, Saulo Vallory, Wagner
  B. Soares, Artur Tchernychev, Valentina De Rosa, Jason Wong
  (http://carrot.org/), Christoph, Daniel Esteban, strftime, Mick@el, rezna,
  Simon Willison (http://simonwillison.net), Anton Ongson, Gabriel Paderni,
  Marco van Oort, penutbutterjelly, Philipp Lenssen, Bjorn Roesbeke
  (http://www.bjornroesbeke.be/), Bug?, Eric Nagel, Tomasz Wesolowski,
  Evertjan Garretsen, Bobby Drake, Blues (http://tech.bluesmoon.info/), Luke
  Godfrey, Pul, uestla, Alan C, Ulrich, Rafal Kukawski, Yves Sucaet,
  sowberry, Norman "zEh" Fuchs, hitwork, Zahlii, johnrembo, Nick Callen,
  Steven Levithan (stevenlevithan.com), ejsanders, Scott Baker, Brian Tafoya
  (http://www.premasolutions.com/), Philippe Jausions
  (http://pear.php.net/user/jausions), Aidan Lister
  (http://aidanlister.com/), Rob, e-mike, HKM, ChaosNo1, metjay, strcasecmp,
  strcmp, Taras Bogach, jpfle, Alexander Ermolaev
  (http://snippets.dzone.com/user/AlexanderErmolaev), DxGx, kilops, Orlando,
  dptr1988, Le Torbi, James (http://www.james-bell.co.uk/), Pedro Tainha
  (http://www.pedrotainha.com), James, Arnout Kazemier
  (http://www.3rd-Eden.com), Chris McMacken, gabriel paderni, Yannoo,
  FGFEmperor, baris ozdil, Tod Gentille, Greg Frazier, jakes, 3D-GRAF, Allan
  Jensen (http://www.winternet.no), Howard Yeend, Benjamin Lupton, davook,
  daniel airton wermann (http://wermann.com.br), Atli T¨®r, Maximusya, Ryan
  W Tenney (http://ryan.10e.us), Alexander M Beedie, fearphage
  (http://http/my.opera.com/fearphage/), Nathan Sepulveda, Victor, Matteo,
  Billy, stensi, Cord, Manish, T.J. Leahy, Riddler
  (http://www.frontierwebdev.com/), Rafa? Kukawski, FremyCompany, Matt
  Bradley, Tim de Koning, Luis Salazar (http://www.freaky-media.com/), Diogo
  Resende, Rival, Andrej Pavlovic, Garagoth, Le Torbi
  (http://www.letorbi.de/), Dino, Josep Sanz (http://www.ws3.es/), rem,
  Russell Walker (http://www.nbill.co.uk/), Jamie Beck
  (http://www.terabit.ca/), setcookie, Michael, YUI Library:
  http://developer.yahoo.com/yui/docs/YAHOO.util.DateLocale.html, Blues at
  http://hacks.bluesmoon.info/strftime/strftime.js, Ben
  (http://benblume.co.uk/), DtTvB
  (http://dt.in.th/2008-09-16.string-length-in-bytes.html), Andreas, William,
  meo, incidence, Cagri Ekin, Amirouche, Amir Habibi
  (http://www.residence-mixte.com/), Luke Smith (http://lucassmith.name),
  Kheang Hok Chin (http://www.distantia.ca/), Jay Klehr, Lorenzo Pisani,
  Tony, Yen-Wei Liu, Greenseed, mk.keck, Leslie Hoare, dude, booeyOH, Ben
  Bryan

  Licensed under the MIT (MIT-LICENSE.txt) license.

  Permission is hereby granted, free of charge, to any person obtaining a
  copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  IN NO EVENT SHALL KEVIN VAN ZONNEVELD BE LIABLE FOR ANY CLAIM, DAMAGES
  OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  OTHER DEALINGS IN THE SOFTWARE.
  */

  function sprintf () {
    // http://kevin.vanzonneveld.net
    // +   original by: Ash Searle (http://hexmen.com/blog/)
    // + namespaced by: Michael White (http://getsprink.com)
    // +    tweaked by: Jack
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: Paulo Freitas
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Dj
    // +   improved by: Allidylls
    // *     example 1: sprintf("%01.2f", 123.1);
    // *     returns 1: 123.10
    // *     example 2: sprintf("[%10s]", 'monkey');
    // *     returns 2: '[    monkey]'
    // *     example 3: sprintf("[%'#10s]", 'monkey');
    // *     returns 3: '[####monkey]'
    // *     example 4: sprintf("%d", 123456789012345);
    // *     returns 4: '123456789012345'
    var regex = /%%|%(\d+\$)?([-+\'#0 ]*)(\*\d+\$|\*|\d+)?(\.(\*\d+\$|\*|\d+))?([scboxXuideEfFgG])/g;
    var a = arguments,
      i = 0,
      format = a[i++];

    // pad()
    var pad = function (str, len, chr, leftJustify) {
      if (!chr) {
        chr = ' ';
      }

      var padding = (str.length >= len) ? '' : Array(1 + len - str.length >>> 0).join(chr);
      return leftJustify ? str + padding : padding + str;
    };

    // justify()
    var justify = function (value, prefix, leftJustify, minWidth, zeroPad, customPadChar) {
      var diff = minWidth - value.length;
      if (diff > 0) {
        if (leftJustify || !zeroPad) {
          value = pad(value, minWidth, customPadChar, leftJustify);
        } else {
          value = value.slice(0, prefix.length) + pad('', diff, '0', true) + value.slice(prefix.length);
        }
      }
      return value;
    };

    // formatBaseX()
    var formatBaseX = function (value, base, prefix, leftJustify, minWidth, precision, zeroPad) {
      // Note: casts negative numbers to positive ones
      var number = value >>> 0;
      prefix = prefix && number && {
        '2': '0b',
        '8': '0',
        '16': '0x'
      }[base] || '';
      value = prefix + pad(number.toString(base), precision || 0, '0', false);
      return justify(value, prefix, leftJustify, minWidth, zeroPad);
    };

    // formatString()
    var formatString = function (value, leftJustify, minWidth, precision, zeroPad, customPadChar) {
      if (precision != null) {
        value = value.slice(0, precision);
      }
      return justify(value, '', leftJustify, minWidth, zeroPad, customPadChar);
    };

    // doFormat()
    var doFormat = function (substring, valueIndex, flags, minWidth, _, precision, type) {
      var number;
      var prefix;
      var method;
      var textTransform;
      var value;

      if (substring == '%%') {
        return '%';
      }

      // parse flags
      var leftJustify = false,
        positivePrefix = '',
        zeroPad = false,
        prefixBaseX = false,
        customPadChar = ' ';
      var flagsl = flags.length;
      for (var j = 0; flags && j < flagsl; j++) {
        switch (flags.charAt(j)) {
        case ' ':
          positivePrefix = ' ';
          break;
        case '+':
          positivePrefix = '+';
          break;
        case '-':
          leftJustify = true;
          break;
        case "'":
          customPadChar = flags.charAt(j + 1);
          break;
        case '0':
          zeroPad = true;
          break;
        case '#':
          prefixBaseX = true;
          break;
        }
      }

      // parameters may be null, undefined, empty-string or real valued
      // we want to ignore null, undefined and empty-string values
      if (!minWidth) {
        minWidth = 0;
      } else if (minWidth == '*') {
        minWidth = +a[i++];
      } else if (minWidth.charAt(0) == '*') {
        minWidth = +a[minWidth.slice(1, -1)];
      } else {
        minWidth = +minWidth;
      }

      // Note: undocumented perl feature:
      if (minWidth < 0) {
        minWidth = -minWidth;
        leftJustify = true;
      }

      if (!isFinite(minWidth)) {
        throw new Error('sprintf: (minimum-)width must be finite');
      }

      if (!precision) {
        precision = 'fFeE'.indexOf(type) > -1 ? 6 : (type == 'd') ? 0 : undefined;
      } else if (precision == '*') {
        precision = +a[i++];
      } else if (precision.charAt(0) == '*') {
        precision = +a[precision.slice(1, -1)];
      } else {
        precision = +precision;
      }

      // grab value using valueIndex if required?
      value = valueIndex ? a[valueIndex.slice(0, -1)] : a[i++];

      switch (type) {
      case 's':
        return formatString(String(value), leftJustify, minWidth, precision, zeroPad, customPadChar);
      case 'c':
        return formatString(String.fromCharCode(+value), leftJustify, minWidth, precision, zeroPad);
      case 'b':
        return formatBaseX(value, 2, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'o':
        return formatBaseX(value, 8, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'x':
        return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'X':
        return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad).toUpperCase();
      case 'u':
        return formatBaseX(value, 10, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
      case 'i':
      case 'd':
        number = +value || 0;
        number = Math.round(number - number % 1); // Plain Math.round doesn't just truncate
        prefix = number < 0 ? '-' : positivePrefix;
        value = prefix + pad(String(Math.abs(number)), precision, '0', false);
        return justify(value, prefix, leftJustify, minWidth, zeroPad);
      case 'e':
      case 'E':
      case 'f': // Should handle locales (as per setlocale)
      case 'F':
      case 'g':
      case 'G':
        number = +value;
        prefix = number < 0 ? '-' : positivePrefix;
        method = ['toExponential', 'toFixed', 'toPrecision']['efg'.indexOf(type.toLowerCase())];
        textTransform = ['toString', 'toUpperCase']['eEfFgG'.indexOf(type) % 2];
        value = prefix + Math.abs(number)[method](precision);
        return justify(value, prefix, leftJustify, minWidth, zeroPad)[textTransform]();
      default:
        return substring;
      }
    };

    return format.replace(regex, doFormat);
  }

  /**
   * Represents a Gregorian date in a more precise format than the JavaScript Date object.
   * In addition to submillisecond precision, this object can also represent leap seconds.
   * @alias GregorianDate
   * @constructor
   *
   * @param {Number} [year] The year as a whole number.
   * @param {Number} [month] The month as a whole number with range [1, 12].
   * @param {Number} [day] The day of the month as a whole number starting at 1.
   * @param {Number} [hour] The hour as a whole number with range [0, 23].
   * @param {Number} [minute] The minute of the hour as a whole number with range [0, 59].
   * @param {Number} [second] The second of the minute as a whole number with range [0, 60], with 60 representing a leap second.
   * @param {Number} [millisecond] The millisecond of the second as a floating point number with range [0.0, 1000.0).
   * @param {Boolean} [isLeapSecond] Whether this time is during a leap second.
   *
   * @see JulianDate#toGregorianDate
   */
  function GregorianDate(
    year,
    month,
    day,
    hour,
    minute,
    second,
    millisecond,
    isLeapSecond
  ) {
    /**
     * Gets or sets the year as a whole number.
     * @type {Number}
     */
    this.year = year;
    /**
     * Gets or sets the month as a whole number with range [1, 12].
     * @type {Number}
     */
    this.month = month;
    /**
     * Gets or sets the day of the month as a whole number starting at 1.
     * @type {Number}
     */
    this.day = day;
    /**
     * Gets or sets the hour as a whole number with range [0, 23].
     * @type {Number}
     */
    this.hour = hour;
    /**
     * Gets or sets the minute of the hour as a whole number with range [0, 59].
     * @type {Number}
     */
    this.minute = minute;
    /**
     * Gets or sets the second of the minute as a whole number with range [0, 60], with 60 representing a leap second.
     * @type {Number}
     */
    this.second = second;
    /**
     * Gets or sets the millisecond of the second as a floating point number with range [0.0, 1000.0).
     * @type {Number}
     */
    this.millisecond = millisecond;
    /**
     * Gets or sets whether this time is during a leap second.
     * @type {Boolean}
     */
    this.isLeapSecond = isLeapSecond;
  }

  /**
   * Determines if a given date is a leap year.
   *
   * @function isLeapYear
   *
   * @param {Number} year The year to be tested.
   * @returns {Boolean} True if <code>year</code> is a leap year.
   *
   * @example
   * var leapYear = Cesium.isLeapYear(2000); // true
   */
  function isLeapYear(year) {
    //>>includeStart('debug', pragmas.debug);
    if (year === null || isNaN(year)) {
      throw new DeveloperError("year is required and must be a number.");
    }
    //>>includeEnd('debug');

    return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
  }

  /**
   * Describes a single leap second, which is constructed from a {@link JulianDate} and a
   * numerical offset representing the number of seconds TAI is ahead of the UTC time standard.
   * @alias LeapSecond
   * @constructor
   *
   * @param {JulianDate} [date] A Julian date representing the time of the leap second.
   * @param {Number} [offset] The cumulative number of seconds that TAI is ahead of UTC at the provided date.
   */
  function LeapSecond(date, offset) {
    /**
     * Gets or sets the date at which this leap second occurs.
     * @type {JulianDate}
     */
    this.julianDate = date;

    /**
     * Gets or sets the cumulative number of seconds between the UTC and TAI time standards at the time
     * of this leap second.
     * @type {Number}
     */
    this.offset = offset;
  }

  /**
   * Constants for time conversions like those done by {@link JulianDate}.
   *
   * @namespace TimeConstants
   *
   * @see JulianDate
   *
   * @private
   */
  var TimeConstants = {
    /**
     * The number of seconds in one millisecond: <code>0.001</code>
     * @type {Number}
     * @constant
     */
    SECONDS_PER_MILLISECOND: 0.001,

    /**
     * The number of seconds in one minute: <code>60</code>.
     * @type {Number}
     * @constant
     */
    SECONDS_PER_MINUTE: 60.0,

    /**
     * The number of minutes in one hour: <code>60</code>.
     * @type {Number}
     * @constant
     */
    MINUTES_PER_HOUR: 60.0,

    /**
     * The number of hours in one day: <code>24</code>.
     * @type {Number}
     * @constant
     */
    HOURS_PER_DAY: 24.0,

    /**
     * The number of seconds in one hour: <code>3600</code>.
     * @type {Number}
     * @constant
     */
    SECONDS_PER_HOUR: 3600.0,

    /**
     * The number of minutes in one day: <code>1440</code>.
     * @type {Number}
     * @constant
     */
    MINUTES_PER_DAY: 1440.0,

    /**
     * The number of seconds in one day, ignoring leap seconds: <code>86400</code>.
     * @type {Number}
     * @constant
     */
    SECONDS_PER_DAY: 86400.0,

    /**
     * The number of days in one Julian century: <code>36525</code>.
     * @type {Number}
     * @constant
     */
    DAYS_PER_JULIAN_CENTURY: 36525.0,

    /**
     * One trillionth of a second.
     * @type {Number}
     * @constant
     */
    PICOSECOND: 0.000000001,

    /**
     * The number of days to subtract from a Julian date to determine the
     * modified Julian date, which gives the number of days since midnight
     * on November 17, 1858.
     * @type {Number}
     * @constant
     */
    MODIFIED_JULIAN_DATE_DIFFERENCE: 2400000.5,
  };
  var TimeConstants$1 = Object.freeze(TimeConstants);

  /**
   * Provides the type of time standards which JulianDate can take as input.
   *
   * @enum {Number}
   *
   * @see JulianDate
   */
  var TimeStandard = {
    /**
     * Represents the coordinated Universal Time (UTC) time standard.
     *
     * UTC is related to TAI according to the relationship
     * <code>UTC = TAI - deltaT</code> where <code>deltaT</code> is the number of leap
     * seconds which have been introduced as of the time in TAI.
     *
     * @type {Number}
     * @constant
     */
    UTC: 0,

    /**
     * Represents the International Atomic Time (TAI) time standard.
     * TAI is the principal time standard to which the other time standards are related.
     *
     * @type {Number}
     * @constant
     */
    TAI: 1,
  };
  var TimeStandard$1 = Object.freeze(TimeStandard);

  var gregorianDateScratch = new GregorianDate();
  var daysInMonth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
  var daysInLeapFeburary = 29;

  function compareLeapSecondDates(leapSecond, dateToFind) {
    return JulianDate.compare(leapSecond.julianDate, dateToFind.julianDate);
  }

  // we don't really need a leap second instance, anything with a julianDate property will do
  var binarySearchScratchLeapSecond = new LeapSecond();

  function convertUtcToTai(julianDate) {
    //Even though julianDate is in UTC, we'll treat it as TAI and
    //search the leap second table for it.
    binarySearchScratchLeapSecond.julianDate = julianDate;
    var leapSeconds = JulianDate.leapSeconds;
    var index = binarySearch(
      leapSeconds,
      binarySearchScratchLeapSecond,
      compareLeapSecondDates
    );

    if (index < 0) {
      index = ~index;
    }

    if (index >= leapSeconds.length) {
      index = leapSeconds.length - 1;
    }

    var offset = leapSeconds[index].offset;
    if (index > 0) {
      //Now we have the index of the closest leap second that comes on or after our UTC time.
      //However, if the difference between the UTC date being converted and the TAI
      //defined leap second is greater than the offset, we are off by one and need to use
      //the previous leap second.
      var difference = JulianDate.secondsDifference(
        leapSeconds[index].julianDate,
        julianDate
      );
      if (difference > offset) {
        index--;
        offset = leapSeconds[index].offset;
      }
    }

    JulianDate.addSeconds(julianDate, offset, julianDate);
  }

  function convertTaiToUtc(julianDate, result) {
    binarySearchScratchLeapSecond.julianDate = julianDate;
    var leapSeconds = JulianDate.leapSeconds;
    var index = binarySearch(
      leapSeconds,
      binarySearchScratchLeapSecond,
      compareLeapSecondDates
    );
    if (index < 0) {
      index = ~index;
    }

    //All times before our first leap second get the first offset.
    if (index === 0) {
      return JulianDate.addSeconds(julianDate, -leapSeconds[0].offset, result);
    }

    //All times after our leap second get the last offset.
    if (index >= leapSeconds.length) {
      return JulianDate.addSeconds(
        julianDate,
        -leapSeconds[index - 1].offset,
        result
      );
    }

    //Compute the difference between the found leap second and the time we are converting.
    var difference = JulianDate.secondsDifference(
      leapSeconds[index].julianDate,
      julianDate
    );

    if (difference === 0) {
      //The date is in our leap second table.
      return JulianDate.addSeconds(
        julianDate,
        -leapSeconds[index].offset,
        result
      );
    }

    if (difference <= 1.0) {
      //The requested date is during the moment of a leap second, then we cannot convert to UTC
      return undefined;
    }

    //The time is in between two leap seconds, index is the leap second after the date
    //we're converting, so we subtract one to get the correct LeapSecond instance.
    return JulianDate.addSeconds(
      julianDate,
      -leapSeconds[--index].offset,
      result
    );
  }

  function setComponents(wholeDays, secondsOfDay, julianDate) {
    var extraDays = (secondsOfDay / TimeConstants$1.SECONDS_PER_DAY) | 0;
    wholeDays += extraDays;
    secondsOfDay -= TimeConstants$1.SECONDS_PER_DAY * extraDays;

    if (secondsOfDay < 0) {
      wholeDays--;
      secondsOfDay += TimeConstants$1.SECONDS_PER_DAY;
    }

    julianDate.dayNumber = wholeDays;
    julianDate.secondsOfDay = secondsOfDay;
    return julianDate;
  }

  function computeJulianDateComponents(
    year,
    month,
    day,
    hour,
    minute,
    second,
    millisecond
  ) {
    // Algorithm from page 604 of the Explanatory Supplement to the
    // Astronomical Almanac (Seidelmann 1992).

    var a = ((month - 14) / 12) | 0;
    var b = year + 4800 + a;
    var dayNumber =
      (((1461 * b) / 4) | 0) +
      (((367 * (month - 2 - 12 * a)) / 12) | 0) -
      (((3 * (((b + 100) / 100) | 0)) / 4) | 0) +
      day -
      32075;

    // JulianDates are noon-based
    hour = hour - 12;
    if (hour < 0) {
      hour += 24;
    }

    var secondsOfDay =
      second +
      (hour * TimeConstants$1.SECONDS_PER_HOUR +
        minute * TimeConstants$1.SECONDS_PER_MINUTE +
        millisecond * TimeConstants$1.SECONDS_PER_MILLISECOND);

    if (secondsOfDay >= 43200.0) {
      dayNumber -= 1;
    }

    return [dayNumber, secondsOfDay];
  }

  //Regular expressions used for ISO8601 date parsing.
  //YYYY
  var matchCalendarYear = /^(\d{4})$/;
  //YYYY-MM (YYYYMM is invalid)
  var matchCalendarMonth = /^(\d{4})-(\d{2})$/;
  //YYYY-DDD or YYYYDDD
  var matchOrdinalDate = /^(\d{4})-?(\d{3})$/;
  //YYYY-Www or YYYYWww or YYYY-Www-D or YYYYWwwD
  var matchWeekDate = /^(\d{4})-?W(\d{2})-?(\d{1})?$/;
  //YYYY-MM-DD or YYYYMMDD
  var matchCalendarDate = /^(\d{4})-?(\d{2})-?(\d{2})$/;
  // Match utc offset
  var utcOffset = /([Z+\-])?(\d{2})?:?(\d{2})?$/;
  // Match hours HH or HH.xxxxx
  var matchHours = /^(\d{2})(\.\d+)?/.source + utcOffset.source;
  // Match hours/minutes HH:MM HHMM.xxxxx
  var matchHoursMinutes = /^(\d{2}):?(\d{2})(\.\d+)?/.source + utcOffset.source;
  // Match hours/minutes HH:MM:SS HHMMSS.xxxxx
  var matchHoursMinutesSeconds =
    /^(\d{2}):?(\d{2}):?(\d{2})(\.\d+)?/.source + utcOffset.source;

  var iso8601ErrorMessage = "Invalid ISO 8601 date.";

  /**
   * Represents an astronomical Julian date, which is the number of days since noon on January 1, -4712 (4713 BC).
   * For increased precision, this class stores the whole number part of the date and the seconds
   * part of the date in separate components.  In order to be safe for arithmetic and represent
   * leap seconds, the date is always stored in the International Atomic Time standard
   * {@link TimeStandard.TAI}.
   * @alias JulianDate
   * @constructor
   *
   * @param {Number} [julianDayNumber=0.0] The Julian Day Number representing the number of whole days.  Fractional days will also be handled correctly.
   * @param {Number} [secondsOfDay=0.0] The number of seconds into the current Julian Day Number.  Fractional seconds, negative seconds and seconds greater than a day will be handled correctly.
   * @param {TimeStandard} [timeStandard=TimeStandard.UTC] The time standard in which the first two parameters are defined.
   */
  function JulianDate(julianDayNumber, secondsOfDay, timeStandard) {
    /**
     * Gets or sets the number of whole days.
     * @type {Number}
     */
    this.dayNumber = undefined;

    /**
     * Gets or sets the number of seconds into the current day.
     * @type {Number}
     */
    this.secondsOfDay = undefined;

    julianDayNumber = defaultValue(julianDayNumber, 0.0);
    secondsOfDay = defaultValue(secondsOfDay, 0.0);
    timeStandard = defaultValue(timeStandard, TimeStandard$1.UTC);

    //If julianDayNumber is fractional, make it an integer and add the number of seconds the fraction represented.
    var wholeDays = julianDayNumber | 0;
    secondsOfDay =
      secondsOfDay +
      (julianDayNumber - wholeDays) * TimeConstants$1.SECONDS_PER_DAY;

    setComponents(wholeDays, secondsOfDay, this);

    if (timeStandard === TimeStandard$1.UTC) {
      convertUtcToTai(this);
    }
  }

  /**
   * Creates a new instance from a GregorianDate.
   *
   * @param {GregorianDate} date A GregorianDate.
   * @param {JulianDate} [result] An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter or a new instance if none was provided.
   *
   * @exception {DeveloperError} date must be a valid GregorianDate.
   */
  JulianDate.fromGregorianDate = function (date, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!(date instanceof GregorianDate)) {
      throw new DeveloperError("date must be a valid GregorianDate.");
    }
    //>>includeEnd('debug');

    var components = computeJulianDateComponents(
      date.year,
      date.month,
      date.day,
      date.hour,
      date.minute,
      date.second,
      date.millisecond
    );
    if (!defined(result)) {
      return new JulianDate(components[0], components[1], TimeStandard$1.UTC);
    }
    setComponents(components[0], components[1], result);
    convertUtcToTai(result);
    return result;
  };

  /**
   * Creates a new instance from a JavaScript Date.
   *
   * @param {Date} date A JavaScript Date.
   * @param {JulianDate} [result] An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter or a new instance if none was provided.
   *
   * @exception {DeveloperError} date must be a valid JavaScript Date.
   */
  JulianDate.fromDate = function (date, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!(date instanceof Date) || isNaN(date.getTime())) {
      throw new DeveloperError("date must be a valid JavaScript Date.");
    }
    //>>includeEnd('debug');

    var components = computeJulianDateComponents(
      date.getUTCFullYear(),
      date.getUTCMonth() + 1,
      date.getUTCDate(),
      date.getUTCHours(),
      date.getUTCMinutes(),
      date.getUTCSeconds(),
      date.getUTCMilliseconds()
    );
    if (!defined(result)) {
      return new JulianDate(components[0], components[1], TimeStandard$1.UTC);
    }
    setComponents(components[0], components[1], result);
    convertUtcToTai(result);
    return result;
  };

  /**
   * Creates a new instance from a from an {@link http://en.wikipedia.org/wiki/ISO_8601|ISO 8601} date.
   * This method is superior to <code>Date.parse</code> because it will handle all valid formats defined by the ISO 8601
   * specification, including leap seconds and sub-millisecond times, which discarded by most JavaScript implementations.
   *
   * @param {String} iso8601String An ISO 8601 date.
   * @param {JulianDate} [result] An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter or a new instance if none was provided.
   *
   * @exception {DeveloperError} Invalid ISO 8601 date.
   */
  JulianDate.fromIso8601 = function (iso8601String, result) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof iso8601String !== "string") {
      throw new DeveloperError(iso8601ErrorMessage);
    }
    //>>includeEnd('debug');

    //Comma and decimal point both indicate a fractional number according to ISO 8601,
    //start out by blanket replacing , with . which is the only valid such symbol in JS.
    iso8601String = iso8601String.replace(",", ".");

    //Split the string into its date and time components, denoted by a mandatory T
    var tokens = iso8601String.split("T");
    var year;
    var month = 1;
    var day = 1;
    var hour = 0;
    var minute = 0;
    var second = 0;
    var millisecond = 0;

    //Lacking a time is okay, but a missing date is illegal.
    var date = tokens[0];
    var time = tokens[1];
    var tmp;
    var inLeapYear;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(date)) {
      throw new DeveloperError(iso8601ErrorMessage);
    }

    var dashCount;
    //>>includeEnd('debug');

    //First match the date against possible regular expressions.
    tokens = date.match(matchCalendarDate);
    if (tokens !== null) {
      //>>includeStart('debug', pragmas.debug);
      dashCount = date.split("-").length - 1;
      if (dashCount > 0 && dashCount !== 2) {
        throw new DeveloperError(iso8601ErrorMessage);
      }
      //>>includeEnd('debug');
      year = +tokens[1];
      month = +tokens[2];
      day = +tokens[3];
    } else {
      tokens = date.match(matchCalendarMonth);
      if (tokens !== null) {
        year = +tokens[1];
        month = +tokens[2];
      } else {
        tokens = date.match(matchCalendarYear);
        if (tokens !== null) {
          year = +tokens[1];
        } else {
          //Not a year/month/day so it must be an ordinal date.
          var dayOfYear;
          tokens = date.match(matchOrdinalDate);
          if (tokens !== null) {
            year = +tokens[1];
            dayOfYear = +tokens[2];
            inLeapYear = isLeapYear(year);

            //This validation is only applicable for this format.
            //>>includeStart('debug', pragmas.debug);
            if (
              dayOfYear < 1 ||
              (inLeapYear && dayOfYear > 366) ||
              (!inLeapYear && dayOfYear > 365)
            ) {
              throw new DeveloperError(iso8601ErrorMessage);
            }
            //>>includeEnd('debug')
          } else {
            tokens = date.match(matchWeekDate);
            if (tokens !== null) {
              //ISO week date to ordinal date from
              //http://en.wikipedia.org/w/index.php?title=ISO_week_date&oldid=474176775
              year = +tokens[1];
              var weekNumber = +tokens[2];
              var dayOfWeek = +tokens[3] || 0;

              //>>includeStart('debug', pragmas.debug);
              dashCount = date.split("-").length - 1;
              if (
                dashCount > 0 &&
                ((!defined(tokens[3]) && dashCount !== 1) ||
                  (defined(tokens[3]) && dashCount !== 2))
              ) {
                throw new DeveloperError(iso8601ErrorMessage);
              }
              //>>includeEnd('debug')

              var january4 = new Date(Date.UTC(year, 0, 4));
              dayOfYear = weekNumber * 7 + dayOfWeek - january4.getUTCDay() - 3;
            } else {
              //None of our regular expressions succeeded in parsing the date properly.
              //>>includeStart('debug', pragmas.debug);
              throw new DeveloperError(iso8601ErrorMessage);
              //>>includeEnd('debug')
            }
          }
          //Split an ordinal date into month/day.
          tmp = new Date(Date.UTC(year, 0, 1));
          tmp.setUTCDate(dayOfYear);
          month = tmp.getUTCMonth() + 1;
          day = tmp.getUTCDate();
        }
      }
    }

    //Now that we have all of the date components, validate them to make sure nothing is out of range.
    inLeapYear = isLeapYear(year);
    //>>includeStart('debug', pragmas.debug);
    if (
      month < 1 ||
      month > 12 ||
      day < 1 ||
      ((month !== 2 || !inLeapYear) && day > daysInMonth[month - 1]) ||
      (inLeapYear && month === 2 && day > daysInLeapFeburary)
    ) {
      throw new DeveloperError(iso8601ErrorMessage);
    }
    //>>includeEnd('debug')

    //Now move onto the time string, which is much simpler.
    //If no time is specified, it is considered the beginning of the day, UTC to match Javascript's implementation.
    var offsetIndex;
    if (defined(time)) {
      tokens = time.match(matchHoursMinutesSeconds);
      if (tokens !== null) {
        //>>includeStart('debug', pragmas.debug);
        dashCount = time.split(":").length - 1;
        if (dashCount > 0 && dashCount !== 2 && dashCount !== 3) {
          throw new DeveloperError(iso8601ErrorMessage);
        }
        //>>includeEnd('debug')

        hour = +tokens[1];
        minute = +tokens[2];
        second = +tokens[3];
        millisecond = +(tokens[4] || 0) * 1000.0;
        offsetIndex = 5;
      } else {
        tokens = time.match(matchHoursMinutes);
        if (tokens !== null) {
          //>>includeStart('debug', pragmas.debug);
          dashCount = time.split(":").length - 1;
          if (dashCount > 2) {
            throw new DeveloperError(iso8601ErrorMessage);
          }
          //>>includeEnd('debug')

          hour = +tokens[1];
          minute = +tokens[2];
          second = +(tokens[3] || 0) * 60.0;
          offsetIndex = 4;
        } else {
          tokens = time.match(matchHours);
          if (tokens !== null) {
            hour = +tokens[1];
            minute = +(tokens[2] || 0) * 60.0;
            offsetIndex = 3;
          } else {
            //>>includeStart('debug', pragmas.debug);
            throw new DeveloperError(iso8601ErrorMessage);
            //>>includeEnd('debug')
          }
        }
      }

      //Validate that all values are in proper range.  Minutes and hours have special cases at 60 and 24.
      //>>includeStart('debug', pragmas.debug);
      if (
        minute >= 60 ||
        second >= 61 ||
        hour > 24 ||
        (hour === 24 && (minute > 0 || second > 0 || millisecond > 0))
      ) {
        throw new DeveloperError(iso8601ErrorMessage);
      }
      //>>includeEnd('debug');

      //Check the UTC offset value, if no value exists, use local time
      //a Z indicates UTC, + or - are offsets.
      var offset = tokens[offsetIndex];
      var offsetHours = +tokens[offsetIndex + 1];
      var offsetMinutes = +(tokens[offsetIndex + 2] || 0);
      switch (offset) {
        case "+":
          hour = hour - offsetHours;
          minute = minute - offsetMinutes;
          break;
        case "-":
          hour = hour + offsetHours;
          minute = minute + offsetMinutes;
          break;
        case "Z":
          break;
        default:
          minute =
            minute +
            new Date(
              Date.UTC(year, month - 1, day, hour, minute)
            ).getTimezoneOffset();
          break;
      }
    }

    //ISO8601 denotes a leap second by any time having a seconds component of 60 seconds.
    //If that's the case, we need to temporarily subtract a second in order to build a UTC date.
    //Then we add it back in after converting to TAI.
    var isLeapSecond = second === 60;
    if (isLeapSecond) {
      second--;
    }

    //Even if we successfully parsed the string into its components, after applying UTC offset or
    //special cases like 24:00:00 denoting midnight, we need to normalize the data appropriately.

    //milliseconds can never be greater than 1000, and seconds can't be above 60, so we start with minutes
    while (minute >= 60) {
      minute -= 60;
      hour++;
    }

    while (hour >= 24) {
      hour -= 24;
      day++;
    }

    tmp = inLeapYear && month === 2 ? daysInLeapFeburary : daysInMonth[month - 1];
    while (day > tmp) {
      day -= tmp;
      month++;

      if (month > 12) {
        month -= 12;
        year++;
      }

      tmp =
        inLeapYear && month === 2 ? daysInLeapFeburary : daysInMonth[month - 1];
    }

    //If UTC offset is at the beginning/end of the day, minutes can be negative.
    while (minute < 0) {
      minute += 60;
      hour--;
    }

    while (hour < 0) {
      hour += 24;
      day--;
    }

    while (day < 1) {
      month--;
      if (month < 1) {
        month += 12;
        year--;
      }

      tmp =
        inLeapYear && month === 2 ? daysInLeapFeburary : daysInMonth[month - 1];
      day += tmp;
    }

    //Now create the JulianDate components from the Gregorian date and actually create our instance.
    var components = computeJulianDateComponents(
      year,
      month,
      day,
      hour,
      minute,
      second,
      millisecond
    );

    if (!defined(result)) {
      result = new JulianDate(components[0], components[1], TimeStandard$1.UTC);
    } else {
      setComponents(components[0], components[1], result);
      convertUtcToTai(result);
    }

    //If we were on a leap second, add it back.
    if (isLeapSecond) {
      JulianDate.addSeconds(result, 1, result);
    }

    return result;
  };

  /**
   * Creates a new instance that represents the current system time.
   * This is equivalent to calling <code>JulianDate.fromDate(new Date());</code>.
   *
   * @param {JulianDate} [result] An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter or a new instance if none was provided.
   */
  JulianDate.now = function (result) {
    return JulianDate.fromDate(new Date(), result);
  };

  var toGregorianDateScratch = new JulianDate(0, 0, TimeStandard$1.TAI);

  /**
   * Creates a {@link GregorianDate} from the provided instance.
   *
   * @param {JulianDate} julianDate The date to be converted.
   * @param {GregorianDate} [result] An existing instance to use for the result.
   * @returns {GregorianDate} The modified result parameter or a new instance if none was provided.
   */
  JulianDate.toGregorianDate = function (julianDate, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    //>>includeEnd('debug');

    var isLeapSecond = false;
    var thisUtc = convertTaiToUtc(julianDate, toGregorianDateScratch);
    if (!defined(thisUtc)) {
      //Conversion to UTC will fail if we are during a leap second.
      //If that's the case, subtract a second and convert again.
      //JavaScript doesn't support leap seconds, so this results in second 59 being repeated twice.
      JulianDate.addSeconds(julianDate, -1, toGregorianDateScratch);
      thisUtc = convertTaiToUtc(toGregorianDateScratch, toGregorianDateScratch);
      isLeapSecond = true;
    }

    var julianDayNumber = thisUtc.dayNumber;
    var secondsOfDay = thisUtc.secondsOfDay;

    if (secondsOfDay >= 43200.0) {
      julianDayNumber += 1;
    }

    // Algorithm from page 604 of the Explanatory Supplement to the
    // Astronomical Almanac (Seidelmann 1992).
    var L = (julianDayNumber + 68569) | 0;
    var N = ((4 * L) / 146097) | 0;
    L = (L - (((146097 * N + 3) / 4) | 0)) | 0;
    var I = ((4000 * (L + 1)) / 1461001) | 0;
    L = (L - (((1461 * I) / 4) | 0) + 31) | 0;
    var J = ((80 * L) / 2447) | 0;
    var day = (L - (((2447 * J) / 80) | 0)) | 0;
    L = (J / 11) | 0;
    var month = (J + 2 - 12 * L) | 0;
    var year = (100 * (N - 49) + I + L) | 0;

    var hour = (secondsOfDay / TimeConstants$1.SECONDS_PER_HOUR) | 0;
    var remainingSeconds = secondsOfDay - hour * TimeConstants$1.SECONDS_PER_HOUR;
    var minute = (remainingSeconds / TimeConstants$1.SECONDS_PER_MINUTE) | 0;
    remainingSeconds =
      remainingSeconds - minute * TimeConstants$1.SECONDS_PER_MINUTE;
    var second = remainingSeconds | 0;
    var millisecond =
      (remainingSeconds - second) / TimeConstants$1.SECONDS_PER_MILLISECOND;

    // JulianDates are noon-based
    hour += 12;
    if (hour > 23) {
      hour -= 24;
    }

    //If we were on a leap second, add it back.
    if (isLeapSecond) {
      second += 1;
    }

    if (!defined(result)) {
      return new GregorianDate(
        year,
        month,
        day,
        hour,
        minute,
        second,
        millisecond,
        isLeapSecond
      );
    }

    result.year = year;
    result.month = month;
    result.day = day;
    result.hour = hour;
    result.minute = minute;
    result.second = second;
    result.millisecond = millisecond;
    result.isLeapSecond = isLeapSecond;
    return result;
  };

  /**
   * Creates a JavaScript Date from the provided instance.
   * Since JavaScript dates are only accurate to the nearest millisecond and
   * cannot represent a leap second, consider using {@link JulianDate.toGregorianDate} instead.
   * If the provided JulianDate is during a leap second, the previous second is used.
   *
   * @param {JulianDate} julianDate The date to be converted.
   * @returns {Date} A new instance representing the provided date.
   */
  JulianDate.toDate = function (julianDate) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    //>>includeEnd('debug');

    var gDate = JulianDate.toGregorianDate(julianDate, gregorianDateScratch);
    var second = gDate.second;
    if (gDate.isLeapSecond) {
      second -= 1;
    }
    return new Date(
      Date.UTC(
        gDate.year,
        gDate.month - 1,
        gDate.day,
        gDate.hour,
        gDate.minute,
        second,
        gDate.millisecond
      )
    );
  };

  /**
   * Creates an ISO8601 representation of the provided date.
   *
   * @param {JulianDate} julianDate The date to be converted.
   * @param {Number} [precision] The number of fractional digits used to represent the seconds component.  By default, the most precise representation is used.
   * @returns {String} The ISO8601 representation of the provided date.
   */
  JulianDate.toIso8601 = function (julianDate, precision) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    //>>includeEnd('debug');

    var gDate = JulianDate.toGregorianDate(julianDate, gregorianDateScratch);
    var year = gDate.year;
    var month = gDate.month;
    var day = gDate.day;
    var hour = gDate.hour;
    var minute = gDate.minute;
    var second = gDate.second;
    var millisecond = gDate.millisecond;

    // special case - Iso8601.MAXIMUM_VALUE produces a string which we can't parse unless we adjust.
    // 10000-01-01T00:00:00 is the same instant as 9999-12-31T24:00:00
    if (
      year === 10000 &&
      month === 1 &&
      day === 1 &&
      hour === 0 &&
      minute === 0 &&
      second === 0 &&
      millisecond === 0
    ) {
      year = 9999;
      month = 12;
      day = 31;
      hour = 24;
    }

    var millisecondStr;

    if (!defined(precision) && millisecond !== 0) {
      //Forces milliseconds into a number with at least 3 digits to whatever the default toString() precision is.
      millisecondStr = (millisecond * 0.01).toString().replace(".", "");
      return sprintf(
        "%04d-%02d-%02dT%02d:%02d:%02d.%sZ",
        year,
        month,
        day,
        hour,
        minute,
        second,
        millisecondStr
      );
    }

    //Precision is either 0 or milliseconds is 0 with undefined precision, in either case, leave off milliseconds entirely
    if (!defined(precision) || precision === 0) {
      return sprintf(
        "%04d-%02d-%02dT%02d:%02d:%02dZ",
        year,
        month,
        day,
        hour,
        minute,
        second
      );
    }

    //Forces milliseconds into a number with at least 3 digits to whatever the specified precision is.
    millisecondStr = (millisecond * 0.01)
      .toFixed(precision)
      .replace(".", "")
      .slice(0, precision);
    return sprintf(
      "%04d-%02d-%02dT%02d:%02d:%02d.%sZ",
      year,
      month,
      day,
      hour,
      minute,
      second,
      millisecondStr
    );
  };

  /**
   * Duplicates a JulianDate instance.
   *
   * @param {JulianDate} julianDate The date to duplicate.
   * @param {JulianDate} [result] An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter or a new instance if none was provided. Returns undefined if julianDate is undefined.
   */
  JulianDate.clone = function (julianDate, result) {
    if (!defined(julianDate)) {
      return undefined;
    }
    if (!defined(result)) {
      return new JulianDate(
        julianDate.dayNumber,
        julianDate.secondsOfDay,
        TimeStandard$1.TAI
      );
    }
    result.dayNumber = julianDate.dayNumber;
    result.secondsOfDay = julianDate.secondsOfDay;
    return result;
  };

  /**
   * Compares two instances.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Number} A negative value if left is less than right, a positive value if left is greater than right, or zero if left and right are equal.
   */
  JulianDate.compare = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("left is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("right is required.");
    }
    //>>includeEnd('debug');

    var julianDayNumberDifference = left.dayNumber - right.dayNumber;
    if (julianDayNumberDifference !== 0) {
      return julianDayNumberDifference;
    }
    return left.secondsOfDay - right.secondsOfDay;
  };

  /**
   * Compares two instances and returns <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {JulianDate} [left] The first instance.
   * @param {JulianDate} [right] The second instance.
   * @returns {Boolean} <code>true</code> if the dates are equal; otherwise, <code>false</code>.
   */
  JulianDate.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.dayNumber === right.dayNumber &&
        left.secondsOfDay === right.secondsOfDay)
    );
  };

  /**
   * Compares two instances and returns <code>true</code> if they are within <code>epsilon</code> seconds of
   * each other.  That is, in order for the dates to be considered equal (and for
   * this function to return <code>true</code>), the absolute value of the difference between them, in
   * seconds, must be less than <code>epsilon</code>.
   *
   * @param {JulianDate} [left] The first instance.
   * @param {JulianDate} [right] The second instance.
   * @param {Number} [epsilon=0] The maximum number of seconds that should separate the two instances.
   * @returns {Boolean} <code>true</code> if the two dates are within <code>epsilon</code> seconds of each other; otherwise <code>false</code>.
   */
  JulianDate.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(JulianDate.secondsDifference(left, right)) <= epsilon)
    );
  };

  /**
   * Computes the total number of whole and fractional days represented by the provided instance.
   *
   * @param {JulianDate} julianDate The date.
   * @returns {Number} The Julian date as single floating point number.
   */
  JulianDate.totalDays = function (julianDate) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    //>>includeEnd('debug');
    return (
      julianDate.dayNumber +
      julianDate.secondsOfDay / TimeConstants$1.SECONDS_PER_DAY
    );
  };

  /**
   * Computes the difference in seconds between the provided instance.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Number} The difference, in seconds, when subtracting <code>right</code> from <code>left</code>.
   */
  JulianDate.secondsDifference = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("left is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("right is required.");
    }
    //>>includeEnd('debug');

    var dayDifference =
      (left.dayNumber - right.dayNumber) * TimeConstants$1.SECONDS_PER_DAY;
    return dayDifference + (left.secondsOfDay - right.secondsOfDay);
  };

  /**
   * Computes the difference in days between the provided instance.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Number} The difference, in days, when subtracting <code>right</code> from <code>left</code>.
   */
  JulianDate.daysDifference = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(left)) {
      throw new DeveloperError("left is required.");
    }
    if (!defined(right)) {
      throw new DeveloperError("right is required.");
    }
    //>>includeEnd('debug');

    var dayDifference = left.dayNumber - right.dayNumber;
    var secondDifference =
      (left.secondsOfDay - right.secondsOfDay) / TimeConstants$1.SECONDS_PER_DAY;
    return dayDifference + secondDifference;
  };

  /**
   * Computes the number of seconds the provided instance is ahead of UTC.
   *
   * @param {JulianDate} julianDate The date.
   * @returns {Number} The number of seconds the provided instance is ahead of UTC
   */
  JulianDate.computeTaiMinusUtc = function (julianDate) {
    binarySearchScratchLeapSecond.julianDate = julianDate;
    var leapSeconds = JulianDate.leapSeconds;
    var index = binarySearch(
      leapSeconds,
      binarySearchScratchLeapSecond,
      compareLeapSecondDates
    );
    if (index < 0) {
      index = ~index;
      --index;
      if (index < 0) {
        index = 0;
      }
    }
    return leapSeconds[index].offset;
  };

  /**
   * Adds the provided number of seconds to the provided date instance.
   *
   * @param {JulianDate} julianDate The date.
   * @param {Number} seconds The number of seconds to add or subtract.
   * @param {JulianDate} result An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter.
   */
  JulianDate.addSeconds = function (julianDate, seconds, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    if (!defined(seconds)) {
      throw new DeveloperError("seconds is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    return setComponents(
      julianDate.dayNumber,
      julianDate.secondsOfDay + seconds,
      result
    );
  };

  /**
   * Adds the provided number of minutes to the provided date instance.
   *
   * @param {JulianDate} julianDate The date.
   * @param {Number} minutes The number of minutes to add or subtract.
   * @param {JulianDate} result An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter.
   */
  JulianDate.addMinutes = function (julianDate, minutes, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    if (!defined(minutes)) {
      throw new DeveloperError("minutes is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var newSecondsOfDay =
      julianDate.secondsOfDay + minutes * TimeConstants$1.SECONDS_PER_MINUTE;
    return setComponents(julianDate.dayNumber, newSecondsOfDay, result);
  };

  /**
   * Adds the provided number of hours to the provided date instance.
   *
   * @param {JulianDate} julianDate The date.
   * @param {Number} hours The number of hours to add or subtract.
   * @param {JulianDate} result An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter.
   */
  JulianDate.addHours = function (julianDate, hours, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    if (!defined(hours)) {
      throw new DeveloperError("hours is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var newSecondsOfDay =
      julianDate.secondsOfDay + hours * TimeConstants$1.SECONDS_PER_HOUR;
    return setComponents(julianDate.dayNumber, newSecondsOfDay, result);
  };

  /**
   * Adds the provided number of days to the provided date instance.
   *
   * @param {JulianDate} julianDate The date.
   * @param {Number} days The number of days to add or subtract.
   * @param {JulianDate} result An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter.
   */
  JulianDate.addDays = function (julianDate, days, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(julianDate)) {
      throw new DeveloperError("julianDate is required.");
    }
    if (!defined(days)) {
      throw new DeveloperError("days is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var newJulianDayNumber = julianDate.dayNumber + days;
    return setComponents(newJulianDayNumber, julianDate.secondsOfDay, result);
  };

  /**
   * Compares the provided instances and returns <code>true</code> if <code>left</code> is earlier than <code>right</code>, <code>false</code> otherwise.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Boolean} <code>true</code> if <code>left</code> is earlier than <code>right</code>, <code>false</code> otherwise.
   */
  JulianDate.lessThan = function (left, right) {
    return JulianDate.compare(left, right) < 0;
  };

  /**
   * Compares the provided instances and returns <code>true</code> if <code>left</code> is earlier than or equal to <code>right</code>, <code>false</code> otherwise.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Boolean} <code>true</code> if <code>left</code> is earlier than or equal to <code>right</code>, <code>false</code> otherwise.
   */
  JulianDate.lessThanOrEquals = function (left, right) {
    return JulianDate.compare(left, right) <= 0;
  };

  /**
   * Compares the provided instances and returns <code>true</code> if <code>left</code> is later than <code>right</code>, <code>false</code> otherwise.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Boolean} <code>true</code> if <code>left</code> is later than <code>right</code>, <code>false</code> otherwise.
   */
  JulianDate.greaterThan = function (left, right) {
    return JulianDate.compare(left, right) > 0;
  };

  /**
   * Compares the provided instances and returns <code>true</code> if <code>left</code> is later than or equal to <code>right</code>, <code>false</code> otherwise.
   *
   * @param {JulianDate} left The first instance.
   * @param {JulianDate} right The second instance.
   * @returns {Boolean} <code>true</code> if <code>left</code> is later than or equal to <code>right</code>, <code>false</code> otherwise.
   */
  JulianDate.greaterThanOrEquals = function (left, right) {
    return JulianDate.compare(left, right) >= 0;
  };

  /**
   * Duplicates this instance.
   *
   * @param {JulianDate} [result] An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter or a new instance if none was provided.
   */
  JulianDate.prototype.clone = function (result) {
    return JulianDate.clone(this, result);
  };

  /**
   * Compares this and the provided instance and returns <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {JulianDate} [right] The second instance.
   * @returns {Boolean} <code>true</code> if the dates are equal; otherwise, <code>false</code>.
   */
  JulianDate.prototype.equals = function (right) {
    return JulianDate.equals(this, right);
  };

  /**
   * Compares this and the provided instance and returns <code>true</code> if they are within <code>epsilon</code> seconds of
   * each other.  That is, in order for the dates to be considered equal (and for
   * this function to return <code>true</code>), the absolute value of the difference between them, in
   * seconds, must be less than <code>epsilon</code>.
   *
   * @param {JulianDate} [right] The second instance.
   * @param {Number} [epsilon=0] The maximum number of seconds that should separate the two instances.
   * @returns {Boolean} <code>true</code> if the two dates are within <code>epsilon</code> seconds of each other; otherwise <code>false</code>.
   */
  JulianDate.prototype.equalsEpsilon = function (right, epsilon) {
    return JulianDate.equalsEpsilon(this, right, epsilon);
  };

  /**
   * Creates a string representing this date in ISO8601 format.
   *
   * @returns {String} A string representing this date in ISO8601 format.
   */
  JulianDate.prototype.toString = function () {
    return JulianDate.toIso8601(this);
  };

  /**
   * Gets or sets the list of leap seconds used throughout Cesium.
   * @memberof JulianDate
   * @type {LeapSecond[]}
   */
  JulianDate.leapSeconds = [
    new LeapSecond(new JulianDate(2441317, 43210.0, TimeStandard$1.TAI), 10), // January 1, 1972 00:00:00 UTC
    new LeapSecond(new JulianDate(2441499, 43211.0, TimeStandard$1.TAI), 11), // July 1, 1972 00:00:00 UTC
    new LeapSecond(new JulianDate(2441683, 43212.0, TimeStandard$1.TAI), 12), // January 1, 1973 00:00:00 UTC
    new LeapSecond(new JulianDate(2442048, 43213.0, TimeStandard$1.TAI), 13), // January 1, 1974 00:00:00 UTC
    new LeapSecond(new JulianDate(2442413, 43214.0, TimeStandard$1.TAI), 14), // January 1, 1975 00:00:00 UTC
    new LeapSecond(new JulianDate(2442778, 43215.0, TimeStandard$1.TAI), 15), // January 1, 1976 00:00:00 UTC
    new LeapSecond(new JulianDate(2443144, 43216.0, TimeStandard$1.TAI), 16), // January 1, 1977 00:00:00 UTC
    new LeapSecond(new JulianDate(2443509, 43217.0, TimeStandard$1.TAI), 17), // January 1, 1978 00:00:00 UTC
    new LeapSecond(new JulianDate(2443874, 43218.0, TimeStandard$1.TAI), 18), // January 1, 1979 00:00:00 UTC
    new LeapSecond(new JulianDate(2444239, 43219.0, TimeStandard$1.TAI), 19), // January 1, 1980 00:00:00 UTC
    new LeapSecond(new JulianDate(2444786, 43220.0, TimeStandard$1.TAI), 20), // July 1, 1981 00:00:00 UTC
    new LeapSecond(new JulianDate(2445151, 43221.0, TimeStandard$1.TAI), 21), // July 1, 1982 00:00:00 UTC
    new LeapSecond(new JulianDate(2445516, 43222.0, TimeStandard$1.TAI), 22), // July 1, 1983 00:00:00 UTC
    new LeapSecond(new JulianDate(2446247, 43223.0, TimeStandard$1.TAI), 23), // July 1, 1985 00:00:00 UTC
    new LeapSecond(new JulianDate(2447161, 43224.0, TimeStandard$1.TAI), 24), // January 1, 1988 00:00:00 UTC
    new LeapSecond(new JulianDate(2447892, 43225.0, TimeStandard$1.TAI), 25), // January 1, 1990 00:00:00 UTC
    new LeapSecond(new JulianDate(2448257, 43226.0, TimeStandard$1.TAI), 26), // January 1, 1991 00:00:00 UTC
    new LeapSecond(new JulianDate(2448804, 43227.0, TimeStandard$1.TAI), 27), // July 1, 1992 00:00:00 UTC
    new LeapSecond(new JulianDate(2449169, 43228.0, TimeStandard$1.TAI), 28), // July 1, 1993 00:00:00 UTC
    new LeapSecond(new JulianDate(2449534, 43229.0, TimeStandard$1.TAI), 29), // July 1, 1994 00:00:00 UTC
    new LeapSecond(new JulianDate(2450083, 43230.0, TimeStandard$1.TAI), 30), // January 1, 1996 00:00:00 UTC
    new LeapSecond(new JulianDate(2450630, 43231.0, TimeStandard$1.TAI), 31), // July 1, 1997 00:00:00 UTC
    new LeapSecond(new JulianDate(2451179, 43232.0, TimeStandard$1.TAI), 32), // January 1, 1999 00:00:00 UTC
    new LeapSecond(new JulianDate(2453736, 43233.0, TimeStandard$1.TAI), 33), // January 1, 2006 00:00:00 UTC
    new LeapSecond(new JulianDate(2454832, 43234.0, TimeStandard$1.TAI), 34), // January 1, 2009 00:00:00 UTC
    new LeapSecond(new JulianDate(2456109, 43235.0, TimeStandard$1.TAI), 35), // July 1, 2012 00:00:00 UTC
    new LeapSecond(new JulianDate(2457204, 43236.0, TimeStandard$1.TAI), 36), // July 1, 2015 00:00:00 UTC
    new LeapSecond(new JulianDate(2457754, 43237.0, TimeStandard$1.TAI), 37), // January 1, 2017 00:00:00 UTC
  ];

  /**
   * Specifies Earth polar motion coordinates and the difference between UT1 and UTC.
   * These Earth Orientation Parameters (EOP) are primarily used in the transformation from
   * the International Celestial Reference Frame (ICRF) to the International Terrestrial
   * Reference Frame (ITRF).
   *
   * @alias EarthOrientationParameters
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Resource|String} [options.url] The URL from which to obtain EOP data.  If neither this
   *                 parameter nor options.data is specified, all EOP values are assumed
   *                 to be 0.0.  If options.data is specified, this parameter is
   *                 ignored.
   * @param {Object} [options.data] The actual EOP data.  If neither this
   *                 parameter nor options.data is specified, all EOP values are assumed
   *                 to be 0.0.
   * @param {Boolean} [options.addNewLeapSeconds=true] True if leap seconds that
   *                  are specified in the EOP data but not in {@link JulianDate.leapSeconds}
   *                  should be added to {@link JulianDate.leapSeconds}.  False if
   *                  new leap seconds should be handled correctly in the context
   *                  of the EOP data but otherwise ignored.
   *
   * @example
   * // An example EOP data file, EOP.json:
   * {
   *   "columnNames" : ["dateIso8601","modifiedJulianDateUtc","xPoleWanderRadians","yPoleWanderRadians","ut1MinusUtcSeconds","lengthOfDayCorrectionSeconds","xCelestialPoleOffsetRadians","yCelestialPoleOffsetRadians","taiMinusUtcSeconds"],
   *   "samples" : [
   *      "2011-07-01T00:00:00Z",55743.0,2.117957047295119e-7,2.111518721609984e-6,-0.2908948,-2.956e-4,3.393695767766752e-11,3.3452143996557983e-10,34.0,
   *      "2011-07-02T00:00:00Z",55744.0,2.193297093339541e-7,2.115460256837405e-6,-0.29065,-1.824e-4,-8.241832578862112e-11,5.623838700870617e-10,34.0,
   *      "2011-07-03T00:00:00Z",55745.0,2.262286080161428e-7,2.1191157519929706e-6,-0.2905572,1.9e-6,-3.490658503988659e-10,6.981317007977318e-10,34.0
   *   ]
   * }
   *
   * @example
   * // Loading the EOP data
   * var eop = new Cesium.EarthOrientationParameters({ url : 'Data/EOP.json' });
   * Cesium.Transforms.earthOrientationParameters = eop;
   *
   * @private
   */
  function EarthOrientationParameters(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._dates = undefined;
    this._samples = undefined;

    this._dateColumn = -1;
    this._xPoleWanderRadiansColumn = -1;
    this._yPoleWanderRadiansColumn = -1;
    this._ut1MinusUtcSecondsColumn = -1;
    this._xCelestialPoleOffsetRadiansColumn = -1;
    this._yCelestialPoleOffsetRadiansColumn = -1;
    this._taiMinusUtcSecondsColumn = -1;

    this._columnCount = 0;
    this._lastIndex = -1;

    this._downloadPromise = undefined;
    this._dataError = undefined;

    this._addNewLeapSeconds = defaultValue(options.addNewLeapSeconds, true);

    if (defined(options.data)) {
      // Use supplied EOP data.
      onDataReady(this, options.data);
    } else if (defined(options.url)) {
      var resource = Resource.createIfNeeded(options.url);

      // Download EOP data.
      var that = this;
      this._downloadPromise = resource
        .fetchJson()
        .then(function (eopData) {
          onDataReady(that, eopData);
        })
        .otherwise(function () {
          that._dataError =
            "An error occurred while retrieving the EOP data from the URL " +
            resource.url +
            ".";
        });
    } else {
      // Use all zeros for EOP data.
      onDataReady(this, {
        columnNames: [
          "dateIso8601",
          "modifiedJulianDateUtc",
          "xPoleWanderRadians",
          "yPoleWanderRadians",
          "ut1MinusUtcSeconds",
          "lengthOfDayCorrectionSeconds",
          "xCelestialPoleOffsetRadians",
          "yCelestialPoleOffsetRadians",
          "taiMinusUtcSeconds",
        ],
        samples: [],
      });
    }
  }

  /**
   * A default {@link EarthOrientationParameters} instance that returns zero for all EOP values.
   */
  EarthOrientationParameters.NONE = Object.freeze({
    getPromiseToLoad: function () {
      return when.resolve();
    },
    compute: function (date, result) {
      if (!defined(result)) {
        result = new EarthOrientationParametersSample(0.0, 0.0, 0.0, 0.0, 0.0);
      } else {
        result.xPoleWander = 0.0;
        result.yPoleWander = 0.0;
        result.xPoleOffset = 0.0;
        result.yPoleOffset = 0.0;
        result.ut1MinusUtc = 0.0;
      }
      return result;
    },
  });

  /**
   * Gets a promise that, when resolved, indicates that the EOP data has been loaded and is
   * ready to use.
   *
   * @returns {Promise<void>} The promise.
   */
  EarthOrientationParameters.prototype.getPromiseToLoad = function () {
    return when(this._downloadPromise);
  };

  /**
   * Computes the Earth Orientation Parameters (EOP) for a given date by interpolating.
   * If the EOP data has not yet been download, this method returns undefined.
   *
   * @param {JulianDate} date The date for each to evaluate the EOP.
   * @param {EarthOrientationParametersSample} [result] The instance to which to copy the result.
   *        If this parameter is undefined, a new instance is created and returned.
   * @returns {EarthOrientationParametersSample} The EOP evaluated at the given date, or
   *          undefined if the data necessary to evaluate EOP at the date has not yet been
   *          downloaded.
   *
   * @exception {RuntimeError} The loaded EOP data has an error and cannot be used.
   *
   * @see EarthOrientationParameters#getPromiseToLoad
   */
  EarthOrientationParameters.prototype.compute = function (date, result) {
    // We cannot compute until the samples are available.
    if (!defined(this._samples)) {
      if (defined(this._dataError)) {
        throw new RuntimeError(this._dataError);
      }

      return undefined;
    }

    if (!defined(result)) {
      result = new EarthOrientationParametersSample(0.0, 0.0, 0.0, 0.0, 0.0);
    }

    if (this._samples.length === 0) {
      result.xPoleWander = 0.0;
      result.yPoleWander = 0.0;
      result.xPoleOffset = 0.0;
      result.yPoleOffset = 0.0;
      result.ut1MinusUtc = 0.0;
      return result;
    }

    var dates = this._dates;
    var lastIndex = this._lastIndex;

    var before = 0;
    var after = 0;
    if (defined(lastIndex)) {
      var previousIndexDate = dates[lastIndex];
      var nextIndexDate = dates[lastIndex + 1];
      var isAfterPrevious = JulianDate.lessThanOrEquals(previousIndexDate, date);
      var isAfterLastSample = !defined(nextIndexDate);
      var isBeforeNext =
        isAfterLastSample || JulianDate.greaterThanOrEquals(nextIndexDate, date);

      if (isAfterPrevious && isBeforeNext) {
        before = lastIndex;

        if (!isAfterLastSample && nextIndexDate.equals(date)) {
          ++before;
        }
        after = before + 1;

        interpolate(this, dates, this._samples, date, before, after, result);
        return result;
      }
    }

    var index = binarySearch(dates, date, JulianDate.compare, this._dateColumn);
    if (index >= 0) {
      // If the next entry is the same date, use the later entry.  This way, if two entries
      // describe the same moment, one before a leap second and the other after, then we will use
      // the post-leap second data.
      if (index < dates.length - 1 && dates[index + 1].equals(date)) {
        ++index;
      }
      before = index;
      after = index;
    } else {
      after = ~index;
      before = after - 1;

      // Use the first entry if the date requested is before the beginning of the data.
      if (before < 0) {
        before = 0;
      }
    }

    this._lastIndex = before;

    interpolate(this, dates, this._samples, date, before, after, result);
    return result;
  };

  function compareLeapSecondDates$1(leapSecond, dateToFind) {
    return JulianDate.compare(leapSecond.julianDate, dateToFind);
  }

  function onDataReady(eop, eopData) {
    if (!defined(eopData.columnNames)) {
      eop._dataError =
        "Error in loaded EOP data: The columnNames property is required.";
      return;
    }

    if (!defined(eopData.samples)) {
      eop._dataError =
        "Error in loaded EOP data: The samples property is required.";
      return;
    }

    var dateColumn = eopData.columnNames.indexOf("modifiedJulianDateUtc");
    var xPoleWanderRadiansColumn = eopData.columnNames.indexOf(
      "xPoleWanderRadians"
    );
    var yPoleWanderRadiansColumn = eopData.columnNames.indexOf(
      "yPoleWanderRadians"
    );
    var ut1MinusUtcSecondsColumn = eopData.columnNames.indexOf(
      "ut1MinusUtcSeconds"
    );
    var xCelestialPoleOffsetRadiansColumn = eopData.columnNames.indexOf(
      "xCelestialPoleOffsetRadians"
    );
    var yCelestialPoleOffsetRadiansColumn = eopData.columnNames.indexOf(
      "yCelestialPoleOffsetRadians"
    );
    var taiMinusUtcSecondsColumn = eopData.columnNames.indexOf(
      "taiMinusUtcSeconds"
    );

    if (
      dateColumn < 0 ||
      xPoleWanderRadiansColumn < 0 ||
      yPoleWanderRadiansColumn < 0 ||
      ut1MinusUtcSecondsColumn < 0 ||
      xCelestialPoleOffsetRadiansColumn < 0 ||
      yCelestialPoleOffsetRadiansColumn < 0 ||
      taiMinusUtcSecondsColumn < 0
    ) {
      eop._dataError =
        "Error in loaded EOP data: The columnNames property must include modifiedJulianDateUtc, xPoleWanderRadians, yPoleWanderRadians, ut1MinusUtcSeconds, xCelestialPoleOffsetRadians, yCelestialPoleOffsetRadians, and taiMinusUtcSeconds columns";
      return;
    }

    var samples = (eop._samples = eopData.samples);
    var dates = (eop._dates = []);

    eop._dateColumn = dateColumn;
    eop._xPoleWanderRadiansColumn = xPoleWanderRadiansColumn;
    eop._yPoleWanderRadiansColumn = yPoleWanderRadiansColumn;
    eop._ut1MinusUtcSecondsColumn = ut1MinusUtcSecondsColumn;
    eop._xCelestialPoleOffsetRadiansColumn = xCelestialPoleOffsetRadiansColumn;
    eop._yCelestialPoleOffsetRadiansColumn = yCelestialPoleOffsetRadiansColumn;
    eop._taiMinusUtcSecondsColumn = taiMinusUtcSecondsColumn;

    eop._columnCount = eopData.columnNames.length;
    eop._lastIndex = undefined;

    var lastTaiMinusUtc;

    var addNewLeapSeconds = eop._addNewLeapSeconds;

    // Convert the ISO8601 dates to JulianDates.
    for (var i = 0, len = samples.length; i < len; i += eop._columnCount) {
      var mjd = samples[i + dateColumn];
      var taiMinusUtc = samples[i + taiMinusUtcSecondsColumn];
      var day = mjd + TimeConstants$1.MODIFIED_JULIAN_DATE_DIFFERENCE;
      var date = new JulianDate(day, taiMinusUtc, TimeStandard$1.TAI);
      dates.push(date);

      if (addNewLeapSeconds) {
        if (taiMinusUtc !== lastTaiMinusUtc && defined(lastTaiMinusUtc)) {
          // We crossed a leap second boundary, so add the leap second
          // if it does not already exist.
          var leapSeconds = JulianDate.leapSeconds;
          var leapSecondIndex = binarySearch(
            leapSeconds,
            date,
            compareLeapSecondDates$1
          );
          if (leapSecondIndex < 0) {
            var leapSecond = new LeapSecond(date, taiMinusUtc);
            leapSeconds.splice(~leapSecondIndex, 0, leapSecond);
          }
        }
        lastTaiMinusUtc = taiMinusUtc;
      }
    }
  }

  function fillResultFromIndex(eop, samples, index, columnCount, result) {
    var start = index * columnCount;
    result.xPoleWander = samples[start + eop._xPoleWanderRadiansColumn];
    result.yPoleWander = samples[start + eop._yPoleWanderRadiansColumn];
    result.xPoleOffset = samples[start + eop._xCelestialPoleOffsetRadiansColumn];
    result.yPoleOffset = samples[start + eop._yCelestialPoleOffsetRadiansColumn];
    result.ut1MinusUtc = samples[start + eop._ut1MinusUtcSecondsColumn];
  }

  function linearInterp(dx, y1, y2) {
    return y1 + dx * (y2 - y1);
  }

  function interpolate(eop, dates, samples, date, before, after, result) {
    var columnCount = eop._columnCount;

    // First check the bounds on the EOP data
    // If we are after the bounds of the data, return zeros.
    // The 'before' index should never be less than zero.
    if (after > dates.length - 1) {
      result.xPoleWander = 0;
      result.yPoleWander = 0;
      result.xPoleOffset = 0;
      result.yPoleOffset = 0;
      result.ut1MinusUtc = 0;
      return result;
    }

    var beforeDate = dates[before];
    var afterDate = dates[after];
    if (beforeDate.equals(afterDate) || date.equals(beforeDate)) {
      fillResultFromIndex(eop, samples, before, columnCount, result);
      return result;
    } else if (date.equals(afterDate)) {
      fillResultFromIndex(eop, samples, after, columnCount, result);
      return result;
    }

    var factor =
      JulianDate.secondsDifference(date, beforeDate) /
      JulianDate.secondsDifference(afterDate, beforeDate);

    var startBefore = before * columnCount;
    var startAfter = after * columnCount;

    // Handle UT1 leap second edge case
    var beforeUt1MinusUtc = samples[startBefore + eop._ut1MinusUtcSecondsColumn];
    var afterUt1MinusUtc = samples[startAfter + eop._ut1MinusUtcSecondsColumn];

    var offsetDifference = afterUt1MinusUtc - beforeUt1MinusUtc;
    if (offsetDifference > 0.5 || offsetDifference < -0.5) {
      // The absolute difference between the values is more than 0.5, so we may have
      // crossed a leap second.  Check if this is the case and, if so, adjust the
      // afterValue to account for the leap second.  This way, our interpolation will
      // produce reasonable results.
      var beforeTaiMinusUtc =
        samples[startBefore + eop._taiMinusUtcSecondsColumn];
      var afterTaiMinusUtc = samples[startAfter + eop._taiMinusUtcSecondsColumn];
      if (beforeTaiMinusUtc !== afterTaiMinusUtc) {
        if (afterDate.equals(date)) {
          // If we are at the end of the leap second interval, take the second value
          // Otherwise, the interpolation below will yield the wrong side of the
          // discontinuity
          // At the end of the leap second, we need to start accounting for the jump
          beforeUt1MinusUtc = afterUt1MinusUtc;
        } else {
          // Otherwise, remove the leap second so that the interpolation is correct
          afterUt1MinusUtc -= afterTaiMinusUtc - beforeTaiMinusUtc;
        }
      }
    }

    result.xPoleWander = linearInterp(
      factor,
      samples[startBefore + eop._xPoleWanderRadiansColumn],
      samples[startAfter + eop._xPoleWanderRadiansColumn]
    );
    result.yPoleWander = linearInterp(
      factor,
      samples[startBefore + eop._yPoleWanderRadiansColumn],
      samples[startAfter + eop._yPoleWanderRadiansColumn]
    );
    result.xPoleOffset = linearInterp(
      factor,
      samples[startBefore + eop._xCelestialPoleOffsetRadiansColumn],
      samples[startAfter + eop._xCelestialPoleOffsetRadiansColumn]
    );
    result.yPoleOffset = linearInterp(
      factor,
      samples[startBefore + eop._yCelestialPoleOffsetRadiansColumn],
      samples[startAfter + eop._yCelestialPoleOffsetRadiansColumn]
    );
    result.ut1MinusUtc = linearInterp(
      factor,
      beforeUt1MinusUtc,
      afterUt1MinusUtc
    );
    return result;
  }

  /**
   * A rotation expressed as a heading, pitch, and roll. Heading is the rotation about the
   * negative z axis. Pitch is the rotation about the negative y axis. Roll is the rotation about
   * the positive x axis.
   * @alias HeadingPitchRoll
   * @constructor
   *
   * @param {Number} [heading=0.0] The heading component in radians.
   * @param {Number} [pitch=0.0] The pitch component in radians.
   * @param {Number} [roll=0.0] The roll component in radians.
   */
  function HeadingPitchRoll(heading, pitch, roll) {
    /**
     * Gets or sets the heading.
     * @type {Number}
     * @default 0.0
     */
    this.heading = defaultValue(heading, 0.0);
    /**
     * Gets or sets the pitch.
     * @type {Number}
     * @default 0.0
     */
    this.pitch = defaultValue(pitch, 0.0);
    /**
     * Gets or sets the roll.
     * @type {Number}
     * @default 0.0
     */
    this.roll = defaultValue(roll, 0.0);
  }

  /**
   * Computes the heading, pitch and roll from a quaternion (see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles )
   *
   * @param {Quaternion} quaternion The quaternion from which to retrieve heading, pitch, and roll, all expressed in radians.
   * @param {HeadingPitchRoll} [result] The object in which to store the result. If not provided, a new instance is created and returned.
   * @returns {HeadingPitchRoll} The modified result parameter or a new HeadingPitchRoll instance if one was not provided.
   */
  HeadingPitchRoll.fromQuaternion = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(quaternion)) {
      throw new DeveloperError("quaternion is required");
    }
    //>>includeEnd('debug');
    if (!defined(result)) {
      result = new HeadingPitchRoll();
    }
    var test = 2 * (quaternion.w * quaternion.y - quaternion.z * quaternion.x);
    var denominatorRoll =
      1 - 2 * (quaternion.x * quaternion.x + quaternion.y * quaternion.y);
    var numeratorRoll =
      2 * (quaternion.w * quaternion.x + quaternion.y * quaternion.z);
    var denominatorHeading =
      1 - 2 * (quaternion.y * quaternion.y + quaternion.z * quaternion.z);
    var numeratorHeading =
      2 * (quaternion.w * quaternion.z + quaternion.x * quaternion.y);
    result.heading = -Math.atan2(numeratorHeading, denominatorHeading);
    result.roll = Math.atan2(numeratorRoll, denominatorRoll);
    result.pitch = -CesiumMath.asinClamped(test);
    return result;
  };

  /**
   * Returns a new HeadingPitchRoll instance from angles given in degrees.
   *
   * @param {Number} heading the heading in degrees
   * @param {Number} pitch the pitch in degrees
   * @param {Number} roll the heading in degrees
   * @param {HeadingPitchRoll} [result] The object in which to store the result. If not provided, a new instance is created and returned.
   * @returns {HeadingPitchRoll} A new HeadingPitchRoll instance
   */
  HeadingPitchRoll.fromDegrees = function (heading, pitch, roll, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(heading)) {
      throw new DeveloperError("heading is required");
    }
    if (!defined(pitch)) {
      throw new DeveloperError("pitch is required");
    }
    if (!defined(roll)) {
      throw new DeveloperError("roll is required");
    }
    //>>includeEnd('debug');
    if (!defined(result)) {
      result = new HeadingPitchRoll();
    }
    result.heading = heading * CesiumMath.RADIANS_PER_DEGREE;
    result.pitch = pitch * CesiumMath.RADIANS_PER_DEGREE;
    result.roll = roll * CesiumMath.RADIANS_PER_DEGREE;
    return result;
  };

  /**
   * Duplicates a HeadingPitchRoll instance.
   *
   * @param {HeadingPitchRoll} headingPitchRoll The HeadingPitchRoll to duplicate.
   * @param {HeadingPitchRoll} [result] The object onto which to store the result.
   * @returns {HeadingPitchRoll} The modified result parameter or a new HeadingPitchRoll instance if one was not provided. (Returns undefined if headingPitchRoll is undefined)
   */
  HeadingPitchRoll.clone = function (headingPitchRoll, result) {
    if (!defined(headingPitchRoll)) {
      return undefined;
    }
    if (!defined(result)) {
      return new HeadingPitchRoll(
        headingPitchRoll.heading,
        headingPitchRoll.pitch,
        headingPitchRoll.roll
      );
    }
    result.heading = headingPitchRoll.heading;
    result.pitch = headingPitchRoll.pitch;
    result.roll = headingPitchRoll.roll;
    return result;
  };

  /**
   * Compares the provided HeadingPitchRolls componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {HeadingPitchRoll} [left] The first HeadingPitchRoll.
   * @param {HeadingPitchRoll} [right] The second HeadingPitchRoll.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  HeadingPitchRoll.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.heading === right.heading &&
        left.pitch === right.pitch &&
        left.roll === right.roll)
    );
  };

  /**
   * Compares the provided HeadingPitchRolls componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {HeadingPitchRoll} [left] The first HeadingPitchRoll.
   * @param {HeadingPitchRoll} [right] The second HeadingPitchRoll.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  HeadingPitchRoll.equalsEpsilon = function (
    left,
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        CesiumMath.equalsEpsilon(
          left.heading,
          right.heading,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.pitch,
          right.pitch,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          left.roll,
          right.roll,
          relativeEpsilon,
          absoluteEpsilon
        ))
    );
  };

  /**
   * Duplicates this HeadingPitchRoll instance.
   *
   * @param {HeadingPitchRoll} [result] The object onto which to store the result.
   * @returns {HeadingPitchRoll} The modified result parameter or a new HeadingPitchRoll instance if one was not provided.
   */
  HeadingPitchRoll.prototype.clone = function (result) {
    return HeadingPitchRoll.clone(this, result);
  };

  /**
   * Compares this HeadingPitchRoll against the provided HeadingPitchRoll componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {HeadingPitchRoll} [right] The right hand side HeadingPitchRoll.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  HeadingPitchRoll.prototype.equals = function (right) {
    return HeadingPitchRoll.equals(this, right);
  };

  /**
   * Compares this HeadingPitchRoll against the provided HeadingPitchRoll componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {HeadingPitchRoll} [right] The right hand side HeadingPitchRoll.
   * @param {Number} [relativeEpsilon=0] The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  HeadingPitchRoll.prototype.equalsEpsilon = function (
    right,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return HeadingPitchRoll.equalsEpsilon(
      this,
      right,
      relativeEpsilon,
      absoluteEpsilon
    );
  };

  /**
   * Creates a string representing this HeadingPitchRoll in the format '(heading, pitch, roll)' in radians.
   *
   * @returns {String} A string representing the provided HeadingPitchRoll in the format '(heading, pitch, roll)'.
   */
  HeadingPitchRoll.prototype.toString = function () {
    return "(" + this.heading + ", " + this.pitch + ", " + this.roll + ")";
  };

  /**
   * An IAU 2006 XYS value sampled at a particular time.
   *
   * @alias Iau2006XysSample
   * @constructor
   *
   * @param {Number} x The X value.
   * @param {Number} y The Y value.
   * @param {Number} s The S value.
   *
   * @private
   */
  function Iau2006XysSample(x, y, s) {
    /**
     * The X value.
     * @type {Number}
     */
    this.x = x;

    /**
     * The Y value.
     * @type {Number}
     */
    this.y = y;

    /**
     * The S value.
     * @type {Number}
     */
    this.s = s;
  }

  /**
   * A set of IAU2006 XYS data that is used to evaluate the transformation between the International
   * Celestial Reference Frame (ICRF) and the International Terrestrial Reference Frame (ITRF).
   *
   * @alias Iau2006XysData
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Resource|String} [options.xysFileUrlTemplate='Assets/IAU2006_XYS/IAU2006_XYS_{0}.json'] A template URL for obtaining the XYS data.  In the template,
   *                 `{0}` will be replaced with the file index.
   * @param {Number} [options.interpolationOrder=9] The order of interpolation to perform on the XYS data.
   * @param {Number} [options.sampleZeroJulianEphemerisDate=2442396.5] The Julian ephemeris date (JED) of the
   *                 first XYS sample.
   * @param {Number} [options.stepSizeDays=1.0] The step size, in days, between successive XYS samples.
   * @param {Number} [options.samplesPerXysFile=1000] The number of samples in each XYS file.
   * @param {Number} [options.totalSamples=27426] The total number of samples in all XYS files.
   *
   * @private
   */
  function Iau2006XysData(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._xysFileUrlTemplate = Resource.createIfNeeded(
      options.xysFileUrlTemplate
    );
    this._interpolationOrder = defaultValue(options.interpolationOrder, 9);
    this._sampleZeroJulianEphemerisDate = defaultValue(
      options.sampleZeroJulianEphemerisDate,
      2442396.5
    );
    this._sampleZeroDateTT = new JulianDate(
      this._sampleZeroJulianEphemerisDate,
      0.0,
      TimeStandard$1.TAI
    );
    this._stepSizeDays = defaultValue(options.stepSizeDays, 1.0);
    this._samplesPerXysFile = defaultValue(options.samplesPerXysFile, 1000);
    this._totalSamples = defaultValue(options.totalSamples, 27426);
    this._samples = new Array(this._totalSamples * 3);
    this._chunkDownloadsInProgress = [];

    var order = this._interpolationOrder;

    // Compute denominators and X values for interpolation.
    var denom = (this._denominators = new Array(order + 1));
    var xTable = (this._xTable = new Array(order + 1));

    var stepN = Math.pow(this._stepSizeDays, order);

    for (var i = 0; i <= order; ++i) {
      denom[i] = stepN;
      xTable[i] = i * this._stepSizeDays;

      for (var j = 0; j <= order; ++j) {
        if (j !== i) {
          denom[i] *= i - j;
        }
      }

      denom[i] = 1.0 / denom[i];
    }

    // Allocate scratch arrays for interpolation.
    this._work = new Array(order + 1);
    this._coef = new Array(order + 1);
  }

  var julianDateScratch = new JulianDate(0, 0.0, TimeStandard$1.TAI);

  function getDaysSinceEpoch(xys, dayTT, secondTT) {
    var dateTT = julianDateScratch;
    dateTT.dayNumber = dayTT;
    dateTT.secondsOfDay = secondTT;
    return JulianDate.daysDifference(dateTT, xys._sampleZeroDateTT);
  }

  /**
   * Preloads XYS data for a specified date range.
   *
   * @param {Number} startDayTT The Julian day number of the beginning of the interval to preload, expressed in
   *                 the Terrestrial Time (TT) time standard.
   * @param {Number} startSecondTT The seconds past noon of the beginning of the interval to preload, expressed in
   *                 the Terrestrial Time (TT) time standard.
   * @param {Number} stopDayTT The Julian day number of the end of the interval to preload, expressed in
   *                 the Terrestrial Time (TT) time standard.
   * @param {Number} stopSecondTT The seconds past noon of the end of the interval to preload, expressed in
   *                 the Terrestrial Time (TT) time standard.
   * @returns {Promise<void>} A promise that, when resolved, indicates that the requested interval has been
   *                    preloaded.
   */
  Iau2006XysData.prototype.preload = function (
    startDayTT,
    startSecondTT,
    stopDayTT,
    stopSecondTT
  ) {
    var startDaysSinceEpoch = getDaysSinceEpoch(this, startDayTT, startSecondTT);
    var stopDaysSinceEpoch = getDaysSinceEpoch(this, stopDayTT, stopSecondTT);

    var startIndex =
      (startDaysSinceEpoch / this._stepSizeDays - this._interpolationOrder / 2) |
      0;
    if (startIndex < 0) {
      startIndex = 0;
    }

    var stopIndex =
      (stopDaysSinceEpoch / this._stepSizeDays - this._interpolationOrder / 2) |
      (0 + this._interpolationOrder);
    if (stopIndex >= this._totalSamples) {
      stopIndex = this._totalSamples - 1;
    }

    var startChunk = (startIndex / this._samplesPerXysFile) | 0;
    var stopChunk = (stopIndex / this._samplesPerXysFile) | 0;

    var promises = [];
    for (var i = startChunk; i <= stopChunk; ++i) {
      promises.push(requestXysChunk(this, i));
    }

    return when.all(promises);
  };

  /**
   * Computes the XYS values for a given date by interpolating.  If the required data is not yet downloaded,
   * this method will return undefined.
   *
   * @param {Number} dayTT The Julian day number for which to compute the XYS value, expressed in
   *                 the Terrestrial Time (TT) time standard.
   * @param {Number} secondTT The seconds past noon of the date for which to compute the XYS value, expressed in
   *                 the Terrestrial Time (TT) time standard.
   * @param {Iau2006XysSample} [result] The instance to which to copy the interpolated result.  If this parameter
   *                           is undefined, a new instance is allocated and returned.
   * @returns {Iau2006XysSample} The interpolated XYS values, or undefined if the required data for this
   *                             computation has not yet been downloaded.
   *
   * @see Iau2006XysData#preload
   */
  Iau2006XysData.prototype.computeXysRadians = function (
    dayTT,
    secondTT,
    result
  ) {
    var daysSinceEpoch = getDaysSinceEpoch(this, dayTT, secondTT);
    if (daysSinceEpoch < 0.0) {
      // Can't evaluate prior to the epoch of the data.
      return undefined;
    }

    var centerIndex = (daysSinceEpoch / this._stepSizeDays) | 0;
    if (centerIndex >= this._totalSamples) {
      // Can't evaluate after the last sample in the data.
      return undefined;
    }

    var degree = this._interpolationOrder;

    var firstIndex = centerIndex - ((degree / 2) | 0);
    if (firstIndex < 0) {
      firstIndex = 0;
    }
    var lastIndex = firstIndex + degree;
    if (lastIndex >= this._totalSamples) {
      lastIndex = this._totalSamples - 1;
      firstIndex = lastIndex - degree;
      if (firstIndex < 0) {
        firstIndex = 0;
      }
    }

    // Are all the samples we need present?
    // We can assume so if the first and last are present
    var isDataMissing = false;
    var samples = this._samples;
    if (!defined(samples[firstIndex * 3])) {
      requestXysChunk(this, (firstIndex / this._samplesPerXysFile) | 0);
      isDataMissing = true;
    }

    if (!defined(samples[lastIndex * 3])) {
      requestXysChunk(this, (lastIndex / this._samplesPerXysFile) | 0);
      isDataMissing = true;
    }

    if (isDataMissing) {
      return undefined;
    }

    if (!defined(result)) {
      result = new Iau2006XysSample(0.0, 0.0, 0.0);
    } else {
      result.x = 0.0;
      result.y = 0.0;
      result.s = 0.0;
    }

    var x = daysSinceEpoch - firstIndex * this._stepSizeDays;

    var work = this._work;
    var denom = this._denominators;
    var coef = this._coef;
    var xTable = this._xTable;

    var i, j;
    for (i = 0; i <= degree; ++i) {
      work[i] = x - xTable[i];
    }

    for (i = 0; i <= degree; ++i) {
      coef[i] = 1.0;

      for (j = 0; j <= degree; ++j) {
        if (j !== i) {
          coef[i] *= work[j];
        }
      }

      coef[i] *= denom[i];

      var sampleIndex = (firstIndex + i) * 3;
      result.x += coef[i] * samples[sampleIndex++];
      result.y += coef[i] * samples[sampleIndex++];
      result.s += coef[i] * samples[sampleIndex];
    }

    return result;
  };

  function requestXysChunk(xysData, chunkIndex) {
    if (xysData._chunkDownloadsInProgress[chunkIndex]) {
      // Chunk has already been requested.
      return xysData._chunkDownloadsInProgress[chunkIndex];
    }

    var deferred = when.defer();

    xysData._chunkDownloadsInProgress[chunkIndex] = deferred;

    var chunkUrl;
    var xysFileUrlTemplate = xysData._xysFileUrlTemplate;
    if (defined(xysFileUrlTemplate)) {
      chunkUrl = xysFileUrlTemplate.getDerivedResource({
        templateValues: {
          "0": chunkIndex,
        },
      });
    } else {
      chunkUrl = new Resource({
        url: buildModuleUrl(
          "Assets/IAU2006_XYS/IAU2006_XYS_" + chunkIndex + ".json"
        ),
      });
    }

    when(chunkUrl.fetchJson(), function (chunk) {
      xysData._chunkDownloadsInProgress[chunkIndex] = false;

      var samples = xysData._samples;
      var newSamples = chunk.samples;
      var startIndex = chunkIndex * xysData._samplesPerXysFile * 3;

      for (var i = 0, len = newSamples.length; i < len; ++i) {
        samples[startIndex + i] = newSamples[i];
      }

      deferred.resolve();
    });

    return deferred.promise;
  }

  var _supportsFullscreen;
  var _names = {
    requestFullscreen: undefined,
    exitFullscreen: undefined,
    fullscreenEnabled: undefined,
    fullscreenElement: undefined,
    fullscreenchange: undefined,
    fullscreenerror: undefined,
  };

  /**
   * Browser-independent functions for working with the standard fullscreen API.
   *
   * @namespace Fullscreen
   *
   * @see {@link http://dvcs.w3.org/hg/fullscreen/raw-file/tip/Overview.html|W3C Fullscreen Living Specification}
   */
  var Fullscreen = {};

  Object.defineProperties(Fullscreen, {
    /**
     * The element that is currently fullscreen, if any.  To simply check if the
     * browser is in fullscreen mode or not, use {@link Fullscreen#fullscreen}.
     * @memberof Fullscreen
     * @type {Object}
     * @readonly
     */
    element: {
      get: function () {
        if (!Fullscreen.supportsFullscreen()) {
          return undefined;
        }

        return document[_names.fullscreenElement];
      },
    },

    /**
     * The name of the event on the document that is fired when fullscreen is
     * entered or exited.  This event name is intended for use with addEventListener.
     * In your event handler, to determine if the browser is in fullscreen mode or not,
     * use {@link Fullscreen#fullscreen}.
     * @memberof Fullscreen
     * @type {String}
     * @readonly
     */
    changeEventName: {
      get: function () {
        if (!Fullscreen.supportsFullscreen()) {
          return undefined;
        }

        return _names.fullscreenchange;
      },
    },

    /**
     * The name of the event that is fired when a fullscreen error
     * occurs.  This event name is intended for use with addEventListener.
     * @memberof Fullscreen
     * @type {String}
     * @readonly
     */
    errorEventName: {
      get: function () {
        if (!Fullscreen.supportsFullscreen()) {
          return undefined;
        }

        return _names.fullscreenerror;
      },
    },

    /**
     * Determine whether the browser will allow an element to be made fullscreen, or not.
     * For example, by default, iframes cannot go fullscreen unless the containing page
     * adds an "allowfullscreen" attribute (or prefixed equivalent).
     * @memberof Fullscreen
     * @type {Boolean}
     * @readonly
     */
    enabled: {
      get: function () {
        if (!Fullscreen.supportsFullscreen()) {
          return undefined;
        }

        return document[_names.fullscreenEnabled];
      },
    },

    /**
     * Determines if the browser is currently in fullscreen mode.
     * @memberof Fullscreen
     * @type {Boolean}
     * @readonly
     */
    fullscreen: {
      get: function () {
        if (!Fullscreen.supportsFullscreen()) {
          return undefined;
        }

        return Fullscreen.element !== null;
      },
    },
  });

  /**
   * Detects whether the browser supports the standard fullscreen API.
   *
   * @returns {Boolean} <code>true</code> if the browser supports the standard fullscreen API,
   * <code>false</code> otherwise.
   */
  Fullscreen.supportsFullscreen = function () {
    if (defined(_supportsFullscreen)) {
      return _supportsFullscreen;
    }

    _supportsFullscreen = false;

    var body = document.body;
    if (typeof body.requestFullscreen === "function") {
      // go with the unprefixed, standard set of names
      _names.requestFullscreen = "requestFullscreen";
      _names.exitFullscreen = "exitFullscreen";
      _names.fullscreenEnabled = "fullscreenEnabled";
      _names.fullscreenElement = "fullscreenElement";
      _names.fullscreenchange = "fullscreenchange";
      _names.fullscreenerror = "fullscreenerror";
      _supportsFullscreen = true;
      return _supportsFullscreen;
    }

    //check for the correct combination of prefix plus the various names that browsers use
    var prefixes = ["webkit", "moz", "o", "ms", "khtml"];
    var name;
    for (var i = 0, len = prefixes.length; i < len; ++i) {
      var prefix = prefixes[i];

      // casing of Fullscreen differs across browsers
      name = prefix + "RequestFullscreen";
      if (typeof body[name] === "function") {
        _names.requestFullscreen = name;
        _supportsFullscreen = true;
      } else {
        name = prefix + "RequestFullScreen";
        if (typeof body[name] === "function") {
          _names.requestFullscreen = name;
          _supportsFullscreen = true;
        }
      }

      // disagreement about whether it's "exit" as per spec, or "cancel"
      name = prefix + "ExitFullscreen";
      if (typeof document[name] === "function") {
        _names.exitFullscreen = name;
      } else {
        name = prefix + "CancelFullScreen";
        if (typeof document[name] === "function") {
          _names.exitFullscreen = name;
        }
      }

      // casing of Fullscreen differs across browsers
      name = prefix + "FullscreenEnabled";
      if (document[name] !== undefined) {
        _names.fullscreenEnabled = name;
      } else {
        name = prefix + "FullScreenEnabled";
        if (document[name] !== undefined) {
          _names.fullscreenEnabled = name;
        }
      }

      // casing of Fullscreen differs across browsers
      name = prefix + "FullscreenElement";
      if (document[name] !== undefined) {
        _names.fullscreenElement = name;
      } else {
        name = prefix + "FullScreenElement";
        if (document[name] !== undefined) {
          _names.fullscreenElement = name;
        }
      }

      // thankfully, event names are all lowercase per spec
      name = prefix + "fullscreenchange";
      // event names do not have 'on' in the front, but the property on the document does
      if (document["on" + name] !== undefined) {
        //except on IE
        if (prefix === "ms") {
          name = "MSFullscreenChange";
        }
        _names.fullscreenchange = name;
      }

      name = prefix + "fullscreenerror";
      if (document["on" + name] !== undefined) {
        //except on IE
        if (prefix === "ms") {
          name = "MSFullscreenError";
        }
        _names.fullscreenerror = name;
      }
    }

    return _supportsFullscreen;
  };

  /**
   * Asynchronously requests the browser to enter fullscreen mode on the given element.
   * If fullscreen mode is not supported by the browser, does nothing.
   *
   * @param {Object} element The HTML element which will be placed into fullscreen mode.
   * @param {Object} [vrDevice] The HMDVRDevice device.
   *
   * @example
   * // Put the entire page into fullscreen.
   * Cesium.Fullscreen.requestFullscreen(document.body)
   *
   * // Place only the Cesium canvas into fullscreen.
   * Cesium.Fullscreen.requestFullscreen(scene.canvas)
   */
  Fullscreen.requestFullscreen = function (element, vrDevice) {
    if (!Fullscreen.supportsFullscreen()) {
      return;
    }

    element[_names.requestFullscreen]({ vrDisplay: vrDevice });
  };

  /**
   * Asynchronously exits fullscreen mode.  If the browser is not currently
   * in fullscreen, or if fullscreen mode is not supported by the browser, does nothing.
   */
  Fullscreen.exitFullscreen = function () {
    if (!Fullscreen.supportsFullscreen()) {
      return;
    }

    document[_names.exitFullscreen]();
  };

  //For unit tests
  Fullscreen._names = _names;

  var theNavigator;
  if (typeof navigator !== "undefined") {
    theNavigator = navigator;
  } else {
    theNavigator = {};
  }

  function extractVersion(versionString) {
    var parts = versionString.split(".");
    for (var i = 0, len = parts.length; i < len; ++i) {
      parts[i] = parseInt(parts[i], 10);
    }
    return parts;
  }

  var isChromeResult;
  var chromeVersionResult;
  function isChrome() {
    if (!defined(isChromeResult)) {
      isChromeResult = false;
      // Edge contains Chrome in the user agent too
      if (!isEdge()) {
        var fields = / Chrome\/([\.0-9]+)/.exec(theNavigator.userAgent);
        if (fields !== null) {
          isChromeResult = true;
          chromeVersionResult = extractVersion(fields[1]);
        }
      }
    }

    return isChromeResult;
  }

  function chromeVersion() {
    return isChrome() && chromeVersionResult;
  }

  var isSafariResult;
  var safariVersionResult;
  function isSafari() {
    if (!defined(isSafariResult)) {
      isSafariResult = false;

      // Chrome and Edge contain Safari in the user agent too
      if (
        !isChrome() &&
        !isEdge() &&
        / Safari\/[\.0-9]+/.test(theNavigator.userAgent)
      ) {
        var fields = / Version\/([\.0-9]+)/.exec(theNavigator.userAgent);
        if (fields !== null) {
          isSafariResult = true;
          safariVersionResult = extractVersion(fields[1]);
        }
      }
    }

    return isSafariResult;
  }

  function safariVersion() {
    return isSafari() && safariVersionResult;
  }

  var isWebkitResult;
  var webkitVersionResult;
  function isWebkit() {
    if (!defined(isWebkitResult)) {
      isWebkitResult = false;

      var fields = / AppleWebKit\/([\.0-9]+)(\+?)/.exec(theNavigator.userAgent);
      if (fields !== null) {
        isWebkitResult = true;
        webkitVersionResult = extractVersion(fields[1]);
        webkitVersionResult.isNightly = !!fields[2];
      }
    }

    return isWebkitResult;
  }

  function webkitVersion() {
    return isWebkit() && webkitVersionResult;
  }

  var isInternetExplorerResult;
  var internetExplorerVersionResult;
  function isInternetExplorer() {
    if (!defined(isInternetExplorerResult)) {
      isInternetExplorerResult = false;

      var fields;
      if (theNavigator.appName === "Microsoft Internet Explorer") {
        fields = /MSIE ([0-9]{1,}[\.0-9]{0,})/.exec(theNavigator.userAgent);
        if (fields !== null) {
          isInternetExplorerResult = true;
          internetExplorerVersionResult = extractVersion(fields[1]);
        }
      } else if (theNavigator.appName === "Netscape") {
        fields = /Trident\/.*rv:([0-9]{1,}[\.0-9]{0,})/.exec(
          theNavigator.userAgent
        );
        if (fields !== null) {
          isInternetExplorerResult = true;
          internetExplorerVersionResult = extractVersion(fields[1]);
        }
      }
    }
    return isInternetExplorerResult;
  }

  function internetExplorerVersion() {
    return isInternetExplorer() && internetExplorerVersionResult;
  }

  var isEdgeResult;
  var edgeVersionResult;
  function isEdge() {
    if (!defined(isEdgeResult)) {
      isEdgeResult = false;
      var fields = / Edge\/([\.0-9]+)/.exec(theNavigator.userAgent);
      if (fields !== null) {
        isEdgeResult = true;
        edgeVersionResult = extractVersion(fields[1]);
      }
    }
    return isEdgeResult;
  }

  function edgeVersion() {
    return isEdge() && edgeVersionResult;
  }

  var isFirefoxResult;
  var firefoxVersionResult;
  function isFirefox() {
    if (!defined(isFirefoxResult)) {
      isFirefoxResult = false;

      var fields = /Firefox\/([\.0-9]+)/.exec(theNavigator.userAgent);
      if (fields !== null) {
        isFirefoxResult = true;
        firefoxVersionResult = extractVersion(fields[1]);
      }
    }
    return isFirefoxResult;
  }

  var isWindowsResult;
  function isWindows() {
    if (!defined(isWindowsResult)) {
      isWindowsResult = /Windows/i.test(theNavigator.appVersion);
    }
    return isWindowsResult;
  }

  function firefoxVersion() {
    return isFirefox() && firefoxVersionResult;
  }

  var hasPointerEvents;
  function supportsPointerEvents() {
    if (!defined(hasPointerEvents)) {
      //While navigator.pointerEnabled is deprecated in the W3C specification
      //we still need to use it if it exists in order to support browsers
      //that rely on it, such as the Windows WebBrowser control which defines
      //PointerEvent but sets navigator.pointerEnabled to false.

      //Firefox disabled because of https://github.com/CesiumGS/cesium/issues/6372
      hasPointerEvents =
        !isFirefox() &&
        typeof PointerEvent !== "undefined" &&
        (!defined(theNavigator.pointerEnabled) || theNavigator.pointerEnabled);
    }
    return hasPointerEvents;
  }

  var imageRenderingValueResult;
  var supportsImageRenderingPixelatedResult;
  function supportsImageRenderingPixelated() {
    if (!defined(supportsImageRenderingPixelatedResult)) {
      var canvas = document.createElement("canvas");
      canvas.setAttribute(
        "style",
        "image-rendering: -moz-crisp-edges;" + "image-rendering: pixelated;"
      );
      //canvas.style.imageRendering will be undefined, null or an empty string on unsupported browsers.
      var tmp = canvas.style.imageRendering;
      supportsImageRenderingPixelatedResult = defined(tmp) && tmp !== "";
      if (supportsImageRenderingPixelatedResult) {
        imageRenderingValueResult = tmp;
      }
    }
    return supportsImageRenderingPixelatedResult;
  }

  function imageRenderingValue() {
    return supportsImageRenderingPixelated()
      ? imageRenderingValueResult
      : undefined;
  }

  function supportsWebP() {
    //>>includeStart('debug', pragmas.debug);
    if (!supportsWebP.initialized) {
      throw new DeveloperError(
        "You must call FeatureDetection.supportsWebP.initialize and wait for the promise to resolve before calling FeatureDetection.supportsWebP"
      );
    }
    //>>includeEnd('debug');
    return supportsWebP._result;
  }
  supportsWebP._promise = undefined;
  supportsWebP._result = undefined;
  supportsWebP.initialize = function () {
    // From https://developers.google.com/speed/webp/faq#how_can_i_detect_browser_support_for_webp
    if (defined(supportsWebP._promise)) {
      return supportsWebP._promise;
    }

    var supportsWebPDeferred = when.defer();
    supportsWebP._promise = supportsWebPDeferred.promise;
    if (isEdge()) {
      // Edge's WebP support with WebGL is incomplete.
      // See bug report: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/19221241/
      supportsWebP._result = false;
      supportsWebPDeferred.resolve(supportsWebP._result);
      return supportsWebPDeferred.promise;
    }

    var image = new Image();
    image.onload = function () {
      supportsWebP._result = image.width > 0 && image.height > 0;
      supportsWebPDeferred.resolve(supportsWebP._result);
    };

    image.onerror = function () {
      supportsWebP._result = false;
      supportsWebPDeferred.resolve(supportsWebP._result);
    };

    image.src =
      "data:image/webp;base64,UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA";

    return supportsWebPDeferred.promise;
  };
  Object.defineProperties(supportsWebP, {
    initialized: {
      get: function () {
        return defined(supportsWebP._result);
      },
    },
  });

  var typedArrayTypes = [];
  if (typeof ArrayBuffer !== "undefined") {
    typedArrayTypes.push(
      Int8Array,
      Uint8Array,
      Int16Array,
      Uint16Array,
      Int32Array,
      Uint32Array,
      Float32Array,
      Float64Array
    );

    if (typeof Uint8ClampedArray !== "undefined") {
      typedArrayTypes.push(Uint8ClampedArray);
    }

    if (typeof Uint8ClampedArray !== "undefined") {
      typedArrayTypes.push(Uint8ClampedArray);
    }
  }

  /**
   * A set of functions to detect whether the current browser supports
   * various features.
   *
   * @namespace FeatureDetection
   */
  var FeatureDetection = {
    isChrome: isChrome,
    chromeVersion: chromeVersion,
    isSafari: isSafari,
    safariVersion: safariVersion,
    isWebkit: isWebkit,
    webkitVersion: webkitVersion,
    isInternetExplorer: isInternetExplorer,
    internetExplorerVersion: internetExplorerVersion,
    isEdge: isEdge,
    edgeVersion: edgeVersion,
    isFirefox: isFirefox,
    firefoxVersion: firefoxVersion,
    isWindows: isWindows,
    hardwareConcurrency: defaultValue(theNavigator.hardwareConcurrency, 3),
    supportsPointerEvents: supportsPointerEvents,
    supportsImageRenderingPixelated: supportsImageRenderingPixelated,
    supportsWebP: supportsWebP,
    imageRenderingValue: imageRenderingValue,
    typedArrayTypes: typedArrayTypes,
  };

  /**
   * Detects whether the current browser supports the full screen standard.
   *
   * @returns {Boolean} true if the browser supports the full screen standard, false if not.
   *
   * @see Fullscreen
   * @see {@link http://dvcs.w3.org/hg/fullscreen/raw-file/tip/Overview.html|W3C Fullscreen Living Specification}
   */
  FeatureDetection.supportsFullscreen = function () {
    return Fullscreen.supportsFullscreen();
  };

  /**
   * Detects whether the current browser supports typed arrays.
   *
   * @returns {Boolean} true if the browser supports typed arrays, false if not.
   *
   * @see {@link http://www.khronos.org/registry/typedarray/specs/latest/|Typed Array Specification}
   */
  FeatureDetection.supportsTypedArrays = function () {
    return typeof ArrayBuffer !== "undefined";
  };

  /**
   * Detects whether the current browser supports Web Workers.
   *
   * @returns {Boolean} true if the browsers supports Web Workers, false if not.
   *
   * @see {@link http://www.w3.org/TR/workers/}
   */
  FeatureDetection.supportsWebWorkers = function () {
    return typeof Worker !== "undefined";
  };

  /**
   * Detects whether the current browser supports Web Assembly.
   *
   * @returns {Boolean} true if the browsers supports Web Assembly, false if not.
   *
   * @see {@link https://developer.mozilla.org/en-US/docs/WebAssembly}
   */
  FeatureDetection.supportsWebAssembly = function () {
    return typeof WebAssembly !== "undefined" && !FeatureDetection.isEdge();
  };

  /**
   * A set of 4-dimensional coordinates used to represent rotation in 3-dimensional space.
   * @alias Quaternion
   * @constructor
   *
   * @param {Number} [x=0.0] The X component.
   * @param {Number} [y=0.0] The Y component.
   * @param {Number} [z=0.0] The Z component.
   * @param {Number} [w=0.0] The W component.
   *
   * @see PackableForInterpolation
   */
  function Quaternion(x, y, z, w) {
    /**
     * The X component.
     * @type {Number}
     * @default 0.0
     */
    this.x = defaultValue(x, 0.0);

    /**
     * The Y component.
     * @type {Number}
     * @default 0.0
     */
    this.y = defaultValue(y, 0.0);

    /**
     * The Z component.
     * @type {Number}
     * @default 0.0
     */
    this.z = defaultValue(z, 0.0);

    /**
     * The W component.
     * @type {Number}
     * @default 0.0
     */
    this.w = defaultValue(w, 0.0);
  }

  var fromAxisAngleScratch = new Cartesian3();

  /**
   * Computes a quaternion representing a rotation around an axis.
   *
   * @param {Cartesian3} axis The axis of rotation.
   * @param {Number} angle The angle in radians to rotate around the axis.
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if one was not provided.
   */
  Quaternion.fromAxisAngle = function (axis, angle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("axis", axis);
    Check.typeOf.number("angle", angle);
    //>>includeEnd('debug');

    var halfAngle = angle / 2.0;
    var s = Math.sin(halfAngle);
    fromAxisAngleScratch = Cartesian3.normalize(axis, fromAxisAngleScratch);

    var x = fromAxisAngleScratch.x * s;
    var y = fromAxisAngleScratch.y * s;
    var z = fromAxisAngleScratch.z * s;
    var w = Math.cos(halfAngle);
    if (!defined(result)) {
      return new Quaternion(x, y, z, w);
    }
    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  var fromRotationMatrixNext = [1, 2, 0];
  var fromRotationMatrixQuat = new Array(3);
  /**
   * Computes a Quaternion from the provided Matrix3 instance.
   *
   * @param {Matrix3} matrix The rotation matrix.
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if one was not provided.
   *
   * @see Matrix3.fromQuaternion
   */
  Quaternion.fromRotationMatrix = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    //>>includeEnd('debug');

    var root;
    var x;
    var y;
    var z;
    var w;

    var m00 = matrix[Matrix3.COLUMN0ROW0];
    var m11 = matrix[Matrix3.COLUMN1ROW1];
    var m22 = matrix[Matrix3.COLUMN2ROW2];
    var trace = m00 + m11 + m22;

    if (trace > 0.0) {
      // |w| > 1/2, may as well choose w > 1/2
      root = Math.sqrt(trace + 1.0); // 2w
      w = 0.5 * root;
      root = 0.5 / root; // 1/(4w)

      x = (matrix[Matrix3.COLUMN1ROW2] - matrix[Matrix3.COLUMN2ROW1]) * root;
      y = (matrix[Matrix3.COLUMN2ROW0] - matrix[Matrix3.COLUMN0ROW2]) * root;
      z = (matrix[Matrix3.COLUMN0ROW1] - matrix[Matrix3.COLUMN1ROW0]) * root;
    } else {
      // |w| <= 1/2
      var next = fromRotationMatrixNext;

      var i = 0;
      if (m11 > m00) {
        i = 1;
      }
      if (m22 > m00 && m22 > m11) {
        i = 2;
      }
      var j = next[i];
      var k = next[j];

      root = Math.sqrt(
        matrix[Matrix3.getElementIndex(i, i)] -
          matrix[Matrix3.getElementIndex(j, j)] -
          matrix[Matrix3.getElementIndex(k, k)] +
          1.0
      );

      var quat = fromRotationMatrixQuat;
      quat[i] = 0.5 * root;
      root = 0.5 / root;
      w =
        (matrix[Matrix3.getElementIndex(k, j)] -
          matrix[Matrix3.getElementIndex(j, k)]) *
        root;
      quat[j] =
        (matrix[Matrix3.getElementIndex(j, i)] +
          matrix[Matrix3.getElementIndex(i, j)]) *
        root;
      quat[k] =
        (matrix[Matrix3.getElementIndex(k, i)] +
          matrix[Matrix3.getElementIndex(i, k)]) *
        root;

      x = -quat[0];
      y = -quat[1];
      z = -quat[2];
    }

    if (!defined(result)) {
      return new Quaternion(x, y, z, w);
    }
    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  var scratchHPRQuaternion = new Quaternion();
  var scratchHeadingQuaternion = new Quaternion();
  var scratchPitchQuaternion = new Quaternion();
  var scratchRollQuaternion = new Quaternion();

  /**
   * Computes a rotation from the given heading, pitch and roll angles. Heading is the rotation about the
   * negative z axis. Pitch is the rotation about the negative y axis. Roll is the rotation about
   * the positive x axis.
   *
   * @param {HeadingPitchRoll} headingPitchRoll The rotation expressed as a heading, pitch and roll.
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if none was provided.
   */
  Quaternion.fromHeadingPitchRoll = function (headingPitchRoll, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("headingPitchRoll", headingPitchRoll);
    //>>includeEnd('debug');

    scratchRollQuaternion = Quaternion.fromAxisAngle(
      Cartesian3.UNIT_X,
      headingPitchRoll.roll,
      scratchHPRQuaternion
    );
    scratchPitchQuaternion = Quaternion.fromAxisAngle(
      Cartesian3.UNIT_Y,
      -headingPitchRoll.pitch,
      result
    );
    result = Quaternion.multiply(
      scratchPitchQuaternion,
      scratchRollQuaternion,
      scratchPitchQuaternion
    );
    scratchHeadingQuaternion = Quaternion.fromAxisAngle(
      Cartesian3.UNIT_Z,
      -headingPitchRoll.heading,
      scratchHPRQuaternion
    );
    return Quaternion.multiply(scratchHeadingQuaternion, result, result);
  };

  var sampledQuaternionAxis = new Cartesian3();
  var sampledQuaternionRotation = new Cartesian3();
  var sampledQuaternionTempQuaternion = new Quaternion();
  var sampledQuaternionQuaternion0 = new Quaternion();
  var sampledQuaternionQuaternion0Conjugate = new Quaternion();

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Quaternion.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Quaternion} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Quaternion.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.x;
    array[startingIndex++] = value.y;
    array[startingIndex++] = value.z;
    array[startingIndex] = value.w;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Quaternion} [result] The object into which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if one was not provided.
   */
  Quaternion.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Quaternion();
    }
    result.x = array[startingIndex];
    result.y = array[startingIndex + 1];
    result.z = array[startingIndex + 2];
    result.w = array[startingIndex + 3];
    return result;
  };

  /**
   * The number of elements used to store the object into an array in its interpolatable form.
   * @type {Number}
   */
  Quaternion.packedInterpolationLength = 3;

  /**
   * Converts a packed array into a form suitable for interpolation.
   *
   * @param {Number[]} packedArray The packed array.
   * @param {Number} [startingIndex=0] The index of the first element to be converted.
   * @param {Number} [lastIndex=packedArray.length] The index of the last element to be converted.
   * @param {Number[]} [result] The object into which to store the result.
   */
  Quaternion.convertPackedArrayForInterpolation = function (
    packedArray,
    startingIndex,
    lastIndex,
    result
  ) {
    Quaternion.unpack(
      packedArray,
      lastIndex * 4,
      sampledQuaternionQuaternion0Conjugate
    );
    Quaternion.conjugate(
      sampledQuaternionQuaternion0Conjugate,
      sampledQuaternionQuaternion0Conjugate
    );

    for (var i = 0, len = lastIndex - startingIndex + 1; i < len; i++) {
      var offset = i * 3;
      Quaternion.unpack(
        packedArray,
        (startingIndex + i) * 4,
        sampledQuaternionTempQuaternion
      );

      Quaternion.multiply(
        sampledQuaternionTempQuaternion,
        sampledQuaternionQuaternion0Conjugate,
        sampledQuaternionTempQuaternion
      );

      if (sampledQuaternionTempQuaternion.w < 0) {
        Quaternion.negate(
          sampledQuaternionTempQuaternion,
          sampledQuaternionTempQuaternion
        );
      }

      Quaternion.computeAxis(
        sampledQuaternionTempQuaternion,
        sampledQuaternionAxis
      );
      var angle = Quaternion.computeAngle(sampledQuaternionTempQuaternion);
      if (!defined(result)) {
        result = [];
      }
      result[offset] = sampledQuaternionAxis.x * angle;
      result[offset + 1] = sampledQuaternionAxis.y * angle;
      result[offset + 2] = sampledQuaternionAxis.z * angle;
    }
  };

  /**
   * Retrieves an instance from a packed array converted with {@link convertPackedArrayForInterpolation}.
   *
   * @param {Number[]} array The array previously packed for interpolation.
   * @param {Number[]} sourceArray The original packed array.
   * @param {Number} [firstIndex=0] The firstIndex used to convert the array.
   * @param {Number} [lastIndex=packedArray.length] The lastIndex used to convert the array.
   * @param {Quaternion} [result] The object into which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if one was not provided.
   */
  Quaternion.unpackInterpolationResult = function (
    array,
    sourceArray,
    firstIndex,
    lastIndex,
    result
  ) {
    if (!defined(result)) {
      result = new Quaternion();
    }
    Cartesian3.fromArray(array, 0, sampledQuaternionRotation);
    var magnitude = Cartesian3.magnitude(sampledQuaternionRotation);

    Quaternion.unpack(sourceArray, lastIndex * 4, sampledQuaternionQuaternion0);

    if (magnitude === 0) {
      Quaternion.clone(Quaternion.IDENTITY, sampledQuaternionTempQuaternion);
    } else {
      Quaternion.fromAxisAngle(
        sampledQuaternionRotation,
        magnitude,
        sampledQuaternionTempQuaternion
      );
    }

    return Quaternion.multiply(
      sampledQuaternionTempQuaternion,
      sampledQuaternionQuaternion0,
      result
    );
  };

  /**
   * Duplicates a Quaternion instance.
   *
   * @param {Quaternion} quaternion The quaternion to duplicate.
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if one was not provided. (Returns undefined if quaternion is undefined)
   */
  Quaternion.clone = function (quaternion, result) {
    if (!defined(quaternion)) {
      return undefined;
    }

    if (!defined(result)) {
      return new Quaternion(
        quaternion.x,
        quaternion.y,
        quaternion.z,
        quaternion.w
      );
    }

    result.x = quaternion.x;
    result.y = quaternion.y;
    result.z = quaternion.z;
    result.w = quaternion.w;
    return result;
  };

  /**
   * Computes the conjugate of the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to conjugate.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.conjugate = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = -quaternion.x;
    result.y = -quaternion.y;
    result.z = -quaternion.z;
    result.w = quaternion.w;
    return result;
  };

  /**
   * Computes magnitude squared for the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to conjugate.
   * @returns {Number} The magnitude squared.
   */
  Quaternion.magnitudeSquared = function (quaternion) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    //>>includeEnd('debug');

    return (
      quaternion.x * quaternion.x +
      quaternion.y * quaternion.y +
      quaternion.z * quaternion.z +
      quaternion.w * quaternion.w
    );
  };

  /**
   * Computes magnitude for the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to conjugate.
   * @returns {Number} The magnitude.
   */
  Quaternion.magnitude = function (quaternion) {
    return Math.sqrt(Quaternion.magnitudeSquared(quaternion));
  };

  /**
   * Computes the normalized form of the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to normalize.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.normalize = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var inverseMagnitude = 1.0 / Quaternion.magnitude(quaternion);
    var x = quaternion.x * inverseMagnitude;
    var y = quaternion.y * inverseMagnitude;
    var z = quaternion.z * inverseMagnitude;
    var w = quaternion.w * inverseMagnitude;

    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  /**
   * Computes the inverse of the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to normalize.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.inverse = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var magnitudeSquared = Quaternion.magnitudeSquared(quaternion);
    result = Quaternion.conjugate(quaternion, result);
    return Quaternion.multiplyByScalar(result, 1.0 / magnitudeSquared, result);
  };

  /**
   * Computes the componentwise sum of two quaternions.
   *
   * @param {Quaternion} left The first quaternion.
   * @param {Quaternion} right The second quaternion.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x + right.x;
    result.y = left.y + right.y;
    result.z = left.z + right.z;
    result.w = left.w + right.w;
    return result;
  };

  /**
   * Computes the componentwise difference of two quaternions.
   *
   * @param {Quaternion} left The first quaternion.
   * @param {Quaternion} right The second quaternion.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = left.x - right.x;
    result.y = left.y - right.y;
    result.z = left.z - right.z;
    result.w = left.w - right.w;
    return result;
  };

  /**
   * Negates the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to be negated.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.negate = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = -quaternion.x;
    result.y = -quaternion.y;
    result.z = -quaternion.z;
    result.w = -quaternion.w;
    return result;
  };

  /**
   * Computes the dot (scalar) product of two quaternions.
   *
   * @param {Quaternion} left The first quaternion.
   * @param {Quaternion} right The second quaternion.
   * @returns {Number} The dot product.
   */
  Quaternion.dot = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    return (
      left.x * right.x + left.y * right.y + left.z * right.z + left.w * right.w
    );
  };

  /**
   * Computes the product of two quaternions.
   *
   * @param {Quaternion} left The first quaternion.
   * @param {Quaternion} right The second quaternion.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.multiply = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var leftX = left.x;
    var leftY = left.y;
    var leftZ = left.z;
    var leftW = left.w;

    var rightX = right.x;
    var rightY = right.y;
    var rightZ = right.z;
    var rightW = right.w;

    var x = leftW * rightX + leftX * rightW + leftY * rightZ - leftZ * rightY;
    var y = leftW * rightY - leftX * rightZ + leftY * rightW + leftZ * rightX;
    var z = leftW * rightZ + leftX * rightY - leftY * rightX + leftZ * rightW;
    var w = leftW * rightW - leftX * rightX - leftY * rightY - leftZ * rightZ;

    result.x = x;
    result.y = y;
    result.z = z;
    result.w = w;
    return result;
  };

  /**
   * Multiplies the provided quaternion componentwise by the provided scalar.
   *
   * @param {Quaternion} quaternion The quaternion to be scaled.
   * @param {Number} scalar The scalar to multiply with.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.multiplyByScalar = function (quaternion, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = quaternion.x * scalar;
    result.y = quaternion.y * scalar;
    result.z = quaternion.z * scalar;
    result.w = quaternion.w * scalar;
    return result;
  };

  /**
   * Divides the provided quaternion componentwise by the provided scalar.
   *
   * @param {Quaternion} quaternion The quaternion to be divided.
   * @param {Number} scalar The scalar to divide by.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.divideByScalar = function (quaternion, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = quaternion.x / scalar;
    result.y = quaternion.y / scalar;
    result.z = quaternion.z / scalar;
    result.w = quaternion.w / scalar;
    return result;
  };

  /**
   * Computes the axis of rotation of the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to use.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Quaternion.computeAxis = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var w = quaternion.w;
    if (Math.abs(w - 1.0) < CesiumMath.EPSILON6) {
      result.x = result.y = result.z = 0;
      return result;
    }

    var scalar = 1.0 / Math.sqrt(1.0 - w * w);

    result.x = quaternion.x * scalar;
    result.y = quaternion.y * scalar;
    result.z = quaternion.z * scalar;
    return result;
  };

  /**
   * Computes the angle of rotation of the provided quaternion.
   *
   * @param {Quaternion} quaternion The quaternion to use.
   * @returns {Number} The angle of rotation.
   */
  Quaternion.computeAngle = function (quaternion) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    //>>includeEnd('debug');

    if (Math.abs(quaternion.w - 1.0) < CesiumMath.EPSILON6) {
      return 0.0;
    }
    return 2.0 * Math.acos(quaternion.w);
  };

  var lerpScratch$3 = new Quaternion();
  /**
   * Computes the linear interpolation or extrapolation at t using the provided quaternions.
   *
   * @param {Quaternion} start The value corresponding to t at 0.0.
   * @param {Quaternion} end The value corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.lerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    lerpScratch$3 = Quaternion.multiplyByScalar(end, t, lerpScratch$3);
    result = Quaternion.multiplyByScalar(start, 1.0 - t, result);
    return Quaternion.add(lerpScratch$3, result, result);
  };

  var slerpEndNegated = new Quaternion();
  var slerpScaledP = new Quaternion();
  var slerpScaledR = new Quaternion();
  /**
   * Computes the spherical linear interpolation or extrapolation at t using the provided quaternions.
   *
   * @param {Quaternion} start The value corresponding to t at 0.0.
   * @param {Quaternion} end The value corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   *
   * @see Quaternion#fastSlerp
   */
  Quaternion.slerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var dot = Quaternion.dot(start, end);

    // The angle between start must be acute. Since q and -q represent
    // the same rotation, negate q to get the acute angle.
    var r = end;
    if (dot < 0.0) {
      dot = -dot;
      r = slerpEndNegated = Quaternion.negate(end, slerpEndNegated);
    }

    // dot > 0, as the dot product approaches 1, the angle between the
    // quaternions vanishes. use linear interpolation.
    if (1.0 - dot < CesiumMath.EPSILON6) {
      return Quaternion.lerp(start, r, t, result);
    }

    var theta = Math.acos(dot);
    slerpScaledP = Quaternion.multiplyByScalar(
      start,
      Math.sin((1 - t) * theta),
      slerpScaledP
    );
    slerpScaledR = Quaternion.multiplyByScalar(
      r,
      Math.sin(t * theta),
      slerpScaledR
    );
    result = Quaternion.add(slerpScaledP, slerpScaledR, result);
    return Quaternion.multiplyByScalar(result, 1.0 / Math.sin(theta), result);
  };

  /**
   * The logarithmic quaternion function.
   *
   * @param {Quaternion} quaternion The unit quaternion.
   * @param {Cartesian3} result The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter.
   */
  Quaternion.log = function (quaternion, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("quaternion", quaternion);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var theta = CesiumMath.acosClamped(quaternion.w);
    var thetaOverSinTheta = 0.0;

    if (theta !== 0.0) {
      thetaOverSinTheta = theta / Math.sin(theta);
    }

    return Cartesian3.multiplyByScalar(quaternion, thetaOverSinTheta, result);
  };

  /**
   * The exponential quaternion function.
   *
   * @param {Cartesian3} cartesian The cartesian.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   */
  Quaternion.exp = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var theta = Cartesian3.magnitude(cartesian);
    var sinThetaOverTheta = 0.0;

    if (theta !== 0.0) {
      sinThetaOverTheta = Math.sin(theta) / theta;
    }

    result.x = cartesian.x * sinThetaOverTheta;
    result.y = cartesian.y * sinThetaOverTheta;
    result.z = cartesian.z * sinThetaOverTheta;
    result.w = Math.cos(theta);

    return result;
  };

  var squadScratchCartesian0 = new Cartesian3();
  var squadScratchCartesian1 = new Cartesian3();
  var squadScratchQuaternion0 = new Quaternion();
  var squadScratchQuaternion1 = new Quaternion();

  /**
   * Computes an inner quadrangle point.
   * <p>This will compute quaternions that ensure a squad curve is C<sup>1</sup>.</p>
   *
   * @param {Quaternion} q0 The first quaternion.
   * @param {Quaternion} q1 The second quaternion.
   * @param {Quaternion} q2 The third quaternion.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   *
   * @see Quaternion#squad
   */
  Quaternion.computeInnerQuadrangle = function (q0, q1, q2, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("q0", q0);
    Check.typeOf.object("q1", q1);
    Check.typeOf.object("q2", q2);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var qInv = Quaternion.conjugate(q1, squadScratchQuaternion0);
    Quaternion.multiply(qInv, q2, squadScratchQuaternion1);
    var cart0 = Quaternion.log(squadScratchQuaternion1, squadScratchCartesian0);

    Quaternion.multiply(qInv, q0, squadScratchQuaternion1);
    var cart1 = Quaternion.log(squadScratchQuaternion1, squadScratchCartesian1);

    Cartesian3.add(cart0, cart1, cart0);
    Cartesian3.multiplyByScalar(cart0, 0.25, cart0);
    Cartesian3.negate(cart0, cart0);
    Quaternion.exp(cart0, squadScratchQuaternion0);

    return Quaternion.multiply(q1, squadScratchQuaternion0, result);
  };

  /**
   * Computes the spherical quadrangle interpolation between quaternions.
   *
   * @param {Quaternion} q0 The first quaternion.
   * @param {Quaternion} q1 The second quaternion.
   * @param {Quaternion} s0 The first inner quadrangle.
   * @param {Quaternion} s1 The second inner quadrangle.
   * @param {Number} t The time in [0,1] used to interpolate.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   *
   *
   * @example
   * // 1. compute the squad interpolation between two quaternions on a curve
   * var s0 = Cesium.Quaternion.computeInnerQuadrangle(quaternions[i - 1], quaternions[i], quaternions[i + 1], new Cesium.Quaternion());
   * var s1 = Cesium.Quaternion.computeInnerQuadrangle(quaternions[i], quaternions[i + 1], quaternions[i + 2], new Cesium.Quaternion());
   * var q = Cesium.Quaternion.squad(quaternions[i], quaternions[i + 1], s0, s1, t, new Cesium.Quaternion());
   *
   * // 2. compute the squad interpolation as above but where the first quaternion is a end point.
   * var s1 = Cesium.Quaternion.computeInnerQuadrangle(quaternions[0], quaternions[1], quaternions[2], new Cesium.Quaternion());
   * var q = Cesium.Quaternion.squad(quaternions[0], quaternions[1], quaternions[0], s1, t, new Cesium.Quaternion());
   *
   * @see Quaternion#computeInnerQuadrangle
   */
  Quaternion.squad = function (q0, q1, s0, s1, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("q0", q0);
    Check.typeOf.object("q1", q1);
    Check.typeOf.object("s0", s0);
    Check.typeOf.object("s1", s1);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var slerp0 = Quaternion.slerp(q0, q1, t, squadScratchQuaternion0);
    var slerp1 = Quaternion.slerp(s0, s1, t, squadScratchQuaternion1);
    return Quaternion.slerp(slerp0, slerp1, 2.0 * t * (1.0 - t), result);
  };

  var fastSlerpScratchQuaternion = new Quaternion();
  var opmu = 1.90110745351730037;
  var u = FeatureDetection.supportsTypedArrays() ? new Float32Array(8) : [];
  var v = FeatureDetection.supportsTypedArrays() ? new Float32Array(8) : [];
  var bT = FeatureDetection.supportsTypedArrays() ? new Float32Array(8) : [];
  var bD = FeatureDetection.supportsTypedArrays() ? new Float32Array(8) : [];

  for (var i = 0; i < 7; ++i) {
    var s = i + 1.0;
    var t = 2.0 * s + 1.0;
    u[i] = 1.0 / (s * t);
    v[i] = s / t;
  }

  u[7] = opmu / (8.0 * 17.0);
  v[7] = (opmu * 8.0) / 17.0;

  /**
   * Computes the spherical linear interpolation or extrapolation at t using the provided quaternions.
   * This implementation is faster than {@link Quaternion#slerp}, but is only accurate up to 10<sup>-6</sup>.
   *
   * @param {Quaternion} start The value corresponding to t at 0.0.
   * @param {Quaternion} end The value corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter.
   *
   * @see Quaternion#slerp
   */
  Quaternion.fastSlerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var x = Quaternion.dot(start, end);

    var sign;
    if (x >= 0) {
      sign = 1.0;
    } else {
      sign = -1.0;
      x = -x;
    }

    var xm1 = x - 1.0;
    var d = 1.0 - t;
    var sqrT = t * t;
    var sqrD = d * d;

    for (var i = 7; i >= 0; --i) {
      bT[i] = (u[i] * sqrT - v[i]) * xm1;
      bD[i] = (u[i] * sqrD - v[i]) * xm1;
    }

    var cT =
      sign *
      t *
      (1.0 +
        bT[0] *
          (1.0 +
            bT[1] *
              (1.0 +
                bT[2] *
                  (1.0 +
                    bT[3] *
                      (1.0 +
                        bT[4] *
                          (1.0 + bT[5] * (1.0 + bT[6] * (1.0 + bT[7]))))))));
    var cD =
      d *
      (1.0 +
        bD[0] *
          (1.0 +
            bD[1] *
              (1.0 +
                bD[2] *
                  (1.0 +
                    bD[3] *
                      (1.0 +
                        bD[4] *
                          (1.0 + bD[5] * (1.0 + bD[6] * (1.0 + bD[7]))))))));

    var temp = Quaternion.multiplyByScalar(start, cD, fastSlerpScratchQuaternion);
    Quaternion.multiplyByScalar(end, cT, result);
    return Quaternion.add(temp, result, result);
  };

  /**
   * Computes the spherical quadrangle interpolation between quaternions.
   * An implementation that is faster than {@link Quaternion#squad}, but less accurate.
   *
   * @param {Quaternion} q0 The first quaternion.
   * @param {Quaternion} q1 The second quaternion.
   * @param {Quaternion} s0 The first inner quadrangle.
   * @param {Quaternion} s1 The second inner quadrangle.
   * @param {Number} t The time in [0,1] used to interpolate.
   * @param {Quaternion} result The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new instance if none was provided.
   *
   * @see Quaternion#squad
   */
  Quaternion.fastSquad = function (q0, q1, s0, s1, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("q0", q0);
    Check.typeOf.object("q1", q1);
    Check.typeOf.object("s0", s0);
    Check.typeOf.object("s1", s1);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var slerp0 = Quaternion.fastSlerp(q0, q1, t, squadScratchQuaternion0);
    var slerp1 = Quaternion.fastSlerp(s0, s1, t, squadScratchQuaternion1);
    return Quaternion.fastSlerp(slerp0, slerp1, 2.0 * t * (1.0 - t), result);
  };

  /**
   * Compares the provided quaternions componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Quaternion} [left] The first quaternion.
   * @param {Quaternion} [right] The second quaternion.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Quaternion.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.x === right.x &&
        left.y === right.y &&
        left.z === right.z &&
        left.w === right.w)
    );
  };

  /**
   * Compares the provided quaternions componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Quaternion} [left] The first quaternion.
   * @param {Quaternion} [right] The second quaternion.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Quaternion.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left.x - right.x) <= epsilon &&
        Math.abs(left.y - right.y) <= epsilon &&
        Math.abs(left.z - right.z) <= epsilon &&
        Math.abs(left.w - right.w) <= epsilon)
    );
  };

  /**
   * An immutable Quaternion instance initialized to (0.0, 0.0, 0.0, 0.0).
   *
   * @type {Quaternion}
   * @constant
   */
  Quaternion.ZERO = Object.freeze(new Quaternion(0.0, 0.0, 0.0, 0.0));

  /**
   * An immutable Quaternion instance initialized to (0.0, 0.0, 0.0, 1.0).
   *
   * @type {Quaternion}
   * @constant
   */
  Quaternion.IDENTITY = Object.freeze(new Quaternion(0.0, 0.0, 0.0, 1.0));

  /**
   * Duplicates this Quaternion instance.
   *
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if one was not provided.
   */
  Quaternion.prototype.clone = function (result) {
    return Quaternion.clone(this, result);
  };

  /**
   * Compares this and the provided quaternion componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Quaternion} [right] The right hand side quaternion.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Quaternion.prototype.equals = function (right) {
    return Quaternion.equals(this, right);
  };

  /**
   * Compares this and the provided quaternion componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Quaternion} [right] The right hand side quaternion.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Quaternion.prototype.equalsEpsilon = function (right, epsilon) {
    return Quaternion.equalsEpsilon(this, right, epsilon);
  };

  /**
   * Returns a string representing this quaternion in the format (x, y, z, w).
   *
   * @returns {String} A string representing this Quaternion.
   */
  Quaternion.prototype.toString = function () {
    return "(" + this.x + ", " + this.y + ", " + this.z + ", " + this.w + ")";
  };

  /**
   * Contains functions for transforming positions to various reference frames.
   *
   * @namespace Transforms
   */
  var Transforms = {};

  var vectorProductLocalFrame = {
    up: {
      south: "east",
      north: "west",
      west: "south",
      east: "north",
    },
    down: {
      south: "west",
      north: "east",
      west: "north",
      east: "south",
    },
    south: {
      up: "west",
      down: "east",
      west: "down",
      east: "up",
    },
    north: {
      up: "east",
      down: "west",
      west: "up",
      east: "down",
    },
    west: {
      up: "north",
      down: "south",
      north: "down",
      south: "up",
    },
    east: {
      up: "south",
      down: "north",
      north: "up",
      south: "down",
    },
  };

  var degeneratePositionLocalFrame = {
    north: [-1, 0, 0],
    east: [0, 1, 0],
    up: [0, 0, 1],
    south: [1, 0, 0],
    west: [0, -1, 0],
    down: [0, 0, -1],
  };

  var localFrameToFixedFrameCache = {};

  var scratchCalculateCartesian = {
    east: new Cartesian3(),
    north: new Cartesian3(),
    up: new Cartesian3(),
    west: new Cartesian3(),
    south: new Cartesian3(),
    down: new Cartesian3(),
  };
  var scratchFirstCartesian = new Cartesian3();
  var scratchSecondCartesian = new Cartesian3();
  var scratchThirdCartesian = new Cartesian3();
  /**
   * Generates a function that computes a 4x4 transformation matrix from a reference frame
   * centered at the provided origin to the provided ellipsoid's fixed reference frame.
   * @param  {String} firstAxis  name of the first axis of the local reference frame. Must be
   *  'east', 'north', 'up', 'west', 'south' or 'down'.
   * @param  {String} secondAxis  name of the second axis of the local reference frame. Must be
   *  'east', 'north', 'up', 'west', 'south' or 'down'.
   * @return {Transforms.LocalFrameToFixedFrame} The function that will computes a
   * 4x4 transformation matrix from a reference frame, with first axis and second axis compliant with the parameters,
   */
  Transforms.localFrameToFixedFrameGenerator = function (firstAxis, secondAxis) {
    if (
      !vectorProductLocalFrame.hasOwnProperty(firstAxis) ||
      !vectorProductLocalFrame[firstAxis].hasOwnProperty(secondAxis)
    ) {
      throw new DeveloperError(
        "firstAxis and secondAxis must be east, north, up, west, south or down."
      );
    }
    var thirdAxis = vectorProductLocalFrame[firstAxis][secondAxis];

    /**
     * Computes a 4x4 transformation matrix from a reference frame
     * centered at the provided origin to the provided ellipsoid's fixed reference frame.
     * @callback Transforms.LocalFrameToFixedFrame
     * @param {Cartesian3} origin The center point of the local reference frame.
     * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
     * @param {Matrix4} [result] The object onto which to store the result.
     * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if none was provided.
     */
    var resultat;
    var hashAxis = firstAxis + secondAxis;
    if (defined(localFrameToFixedFrameCache[hashAxis])) {
      resultat = localFrameToFixedFrameCache[hashAxis];
    } else {
      resultat = function (origin, ellipsoid, result) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(origin)) {
          throw new DeveloperError("origin is required.");
        }
        //>>includeEnd('debug');
        if (!defined(result)) {
          result = new Matrix4();
        }
        if (
          Cartesian3.equalsEpsilon(origin, Cartesian3.ZERO, CesiumMath.EPSILON14)
        ) {
          // If x, y, and z are zero, use the degenerate local frame, which is a special case
          Cartesian3.unpack(
            degeneratePositionLocalFrame[firstAxis],
            0,
            scratchFirstCartesian
          );
          Cartesian3.unpack(
            degeneratePositionLocalFrame[secondAxis],
            0,
            scratchSecondCartesian
          );
          Cartesian3.unpack(
            degeneratePositionLocalFrame[thirdAxis],
            0,
            scratchThirdCartesian
          );
        } else if (
          CesiumMath.equalsEpsilon(origin.x, 0.0, CesiumMath.EPSILON14) &&
          CesiumMath.equalsEpsilon(origin.y, 0.0, CesiumMath.EPSILON14)
        ) {
          // If x and y are zero, assume origin is at a pole, which is a special case.
          var sign = CesiumMath.sign(origin.z);

          Cartesian3.unpack(
            degeneratePositionLocalFrame[firstAxis],
            0,
            scratchFirstCartesian
          );
          if (firstAxis !== "east" && firstAxis !== "west") {
            Cartesian3.multiplyByScalar(
              scratchFirstCartesian,
              sign,
              scratchFirstCartesian
            );
          }

          Cartesian3.unpack(
            degeneratePositionLocalFrame[secondAxis],
            0,
            scratchSecondCartesian
          );
          if (secondAxis !== "east" && secondAxis !== "west") {
            Cartesian3.multiplyByScalar(
              scratchSecondCartesian,
              sign,
              scratchSecondCartesian
            );
          }

          Cartesian3.unpack(
            degeneratePositionLocalFrame[thirdAxis],
            0,
            scratchThirdCartesian
          );
          if (thirdAxis !== "east" && thirdAxis !== "west") {
            Cartesian3.multiplyByScalar(
              scratchThirdCartesian,
              sign,
              scratchThirdCartesian
            );
          }
        } else {
          ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
          ellipsoid.geodeticSurfaceNormal(origin, scratchCalculateCartesian.up);

          var up = scratchCalculateCartesian.up;
          var east = scratchCalculateCartesian.east;
          east.x = -origin.y;
          east.y = origin.x;
          east.z = 0.0;
          Cartesian3.normalize(east, scratchCalculateCartesian.east);
          Cartesian3.cross(up, east, scratchCalculateCartesian.north);

          Cartesian3.multiplyByScalar(
            scratchCalculateCartesian.up,
            -1,
            scratchCalculateCartesian.down
          );
          Cartesian3.multiplyByScalar(
            scratchCalculateCartesian.east,
            -1,
            scratchCalculateCartesian.west
          );
          Cartesian3.multiplyByScalar(
            scratchCalculateCartesian.north,
            -1,
            scratchCalculateCartesian.south
          );

          scratchFirstCartesian = scratchCalculateCartesian[firstAxis];
          scratchSecondCartesian = scratchCalculateCartesian[secondAxis];
          scratchThirdCartesian = scratchCalculateCartesian[thirdAxis];
        }
        result[0] = scratchFirstCartesian.x;
        result[1] = scratchFirstCartesian.y;
        result[2] = scratchFirstCartesian.z;
        result[3] = 0.0;
        result[4] = scratchSecondCartesian.x;
        result[5] = scratchSecondCartesian.y;
        result[6] = scratchSecondCartesian.z;
        result[7] = 0.0;
        result[8] = scratchThirdCartesian.x;
        result[9] = scratchThirdCartesian.y;
        result[10] = scratchThirdCartesian.z;
        result[11] = 0.0;
        result[12] = origin.x;
        result[13] = origin.y;
        result[14] = origin.z;
        result[15] = 1.0;
        return result;
      };
      localFrameToFixedFrameCache[hashAxis] = resultat;
    }
    return resultat;
  };

  /**
   * Computes a 4x4 transformation matrix from a reference frame with an east-north-up axes
   * centered at the provided origin to the provided ellipsoid's fixed reference frame.
   * The local axes are defined as:
   * <ul>
   * <li>The <code>x</code> axis points in the local east direction.</li>
   * <li>The <code>y</code> axis points in the local north direction.</li>
   * <li>The <code>z</code> axis points in the direction of the ellipsoid surface normal which passes through the position.</li>
   * </ul>
   *
   * @function
   * @param {Cartesian3} origin The center point of the local reference frame.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if none was provided.
   *
   * @example
   * // Get the transform from local east-north-up at cartographic (0.0, 0.0) to Earth's fixed frame.
   * var center = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var transform = Cesium.Transforms.eastNorthUpToFixedFrame(center);
   */
  Transforms.eastNorthUpToFixedFrame = Transforms.localFrameToFixedFrameGenerator(
    "east",
    "north"
  );

  /**
   * Computes a 4x4 transformation matrix from a reference frame with an north-east-down axes
   * centered at the provided origin to the provided ellipsoid's fixed reference frame.
   * The local axes are defined as:
   * <ul>
   * <li>The <code>x</code> axis points in the local north direction.</li>
   * <li>The <code>y</code> axis points in the local east direction.</li>
   * <li>The <code>z</code> axis points in the opposite direction of the ellipsoid surface normal which passes through the position.</li>
   * </ul>
   *
   * @function
   * @param {Cartesian3} origin The center point of the local reference frame.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if none was provided.
   *
   * @example
   * // Get the transform from local north-east-down at cartographic (0.0, 0.0) to Earth's fixed frame.
   * var center = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var transform = Cesium.Transforms.northEastDownToFixedFrame(center);
   */
  Transforms.northEastDownToFixedFrame = Transforms.localFrameToFixedFrameGenerator(
    "north",
    "east"
  );

  /**
   * Computes a 4x4 transformation matrix from a reference frame with an north-up-east axes
   * centered at the provided origin to the provided ellipsoid's fixed reference frame.
   * The local axes are defined as:
   * <ul>
   * <li>The <code>x</code> axis points in the local north direction.</li>
   * <li>The <code>y</code> axis points in the direction of the ellipsoid surface normal which passes through the position.</li>
   * <li>The <code>z</code> axis points in the local east direction.</li>
   * </ul>
   *
   * @function
   * @param {Cartesian3} origin The center point of the local reference frame.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if none was provided.
   *
   * @example
   * // Get the transform from local north-up-east at cartographic (0.0, 0.0) to Earth's fixed frame.
   * var center = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var transform = Cesium.Transforms.northUpEastToFixedFrame(center);
   */
  Transforms.northUpEastToFixedFrame = Transforms.localFrameToFixedFrameGenerator(
    "north",
    "up"
  );

  /**
   * Computes a 4x4 transformation matrix from a reference frame with an north-west-up axes
   * centered at the provided origin to the provided ellipsoid's fixed reference frame.
   * The local axes are defined as:
   * <ul>
   * <li>The <code>x</code> axis points in the local north direction.</li>
   * <li>The <code>y</code> axis points in the local west direction.</li>
   * <li>The <code>z</code> axis points in the direction of the ellipsoid surface normal which passes through the position.</li>
   * </ul>
   *
   * @function
   * @param {Cartesian3} origin The center point of the local reference frame.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if none was provided.
   *
   * @example
   * // Get the transform from local north-West-Up at cartographic (0.0, 0.0) to Earth's fixed frame.
   * var center = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var transform = Cesium.Transforms.northWestUpToFixedFrame(center);
   */
  Transforms.northWestUpToFixedFrame = Transforms.localFrameToFixedFrameGenerator(
    "north",
    "west"
  );

  var scratchHPRQuaternion$1 = new Quaternion();
  var scratchScale$2 = new Cartesian3(1.0, 1.0, 1.0);
  var scratchHPRMatrix4 = new Matrix4();

  /**
   * Computes a 4x4 transformation matrix from a reference frame with axes computed from the heading-pitch-roll angles
   * centered at the provided origin to the provided ellipsoid's fixed reference frame. Heading is the rotation from the local north
   * direction where a positive angle is increasing eastward. Pitch is the rotation from the local east-north plane. Positive pitch angles
   * are above the plane. Negative pitch angles are below the plane. Roll is the first rotation applied about the local east axis.
   *
   * @param {Cartesian3} origin The center point of the local reference frame.
   * @param {HeadingPitchRoll} headingPitchRoll The heading, pitch, and roll.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Transforms.LocalFrameToFixedFrame} [fixedFrameTransform=Transforms.eastNorthUpToFixedFrame] A 4x4 transformation
   *  matrix from a reference frame to the provided ellipsoid's fixed reference frame
   * @param {Matrix4} [result] The object onto which to store the result.
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if none was provided.
   *
   * @example
   * // Get the transform from local heading-pitch-roll at cartographic (0.0, 0.0) to Earth's fixed frame.
   * var center = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var heading = -Cesium.Math.PI_OVER_TWO;
   * var pitch = Cesium.Math.PI_OVER_FOUR;
   * var roll = 0.0;
   * var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);
   * var transform = Cesium.Transforms.headingPitchRollToFixedFrame(center, hpr);
   */
  Transforms.headingPitchRollToFixedFrame = function (
    origin,
    headingPitchRoll,
    ellipsoid,
    fixedFrameTransform,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("HeadingPitchRoll", headingPitchRoll);
    //>>includeEnd('debug');

    fixedFrameTransform = defaultValue(
      fixedFrameTransform,
      Transforms.eastNorthUpToFixedFrame
    );
    var hprQuaternion = Quaternion.fromHeadingPitchRoll(
      headingPitchRoll,
      scratchHPRQuaternion$1
    );
    var hprMatrix = Matrix4.fromTranslationQuaternionRotationScale(
      Cartesian3.ZERO,
      hprQuaternion,
      scratchScale$2,
      scratchHPRMatrix4
    );
    result = fixedFrameTransform(origin, ellipsoid, result);
    return Matrix4.multiply(result, hprMatrix, result);
  };

  var scratchENUMatrix4 = new Matrix4();
  var scratchHPRMatrix3 = new Matrix3();

  /**
   * Computes a quaternion from a reference frame with axes computed from the heading-pitch-roll angles
   * centered at the provided origin. Heading is the rotation from the local north
   * direction where a positive angle is increasing eastward. Pitch is the rotation from the local east-north plane. Positive pitch angles
   * are above the plane. Negative pitch angles are below the plane. Roll is the first rotation applied about the local east axis.
   *
   * @param {Cartesian3} origin The center point of the local reference frame.
   * @param {HeadingPitchRoll} headingPitchRoll The heading, pitch, and roll.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Transforms.LocalFrameToFixedFrame} [fixedFrameTransform=Transforms.eastNorthUpToFixedFrame] A 4x4 transformation
   *  matrix from a reference frame to the provided ellipsoid's fixed reference frame
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new Quaternion instance if none was provided.
   *
   * @example
   * // Get the quaternion from local heading-pitch-roll at cartographic (0.0, 0.0) to Earth's fixed frame.
   * var center = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var heading = -Cesium.Math.PI_OVER_TWO;
   * var pitch = Cesium.Math.PI_OVER_FOUR;
   * var roll = 0.0;
   * var hpr = new HeadingPitchRoll(heading, pitch, roll);
   * var quaternion = Cesium.Transforms.headingPitchRollQuaternion(center, hpr);
   */
  Transforms.headingPitchRollQuaternion = function (
    origin,
    headingPitchRoll,
    ellipsoid,
    fixedFrameTransform,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("HeadingPitchRoll", headingPitchRoll);
    //>>includeEnd('debug');

    var transform = Transforms.headingPitchRollToFixedFrame(
      origin,
      headingPitchRoll,
      ellipsoid,
      fixedFrameTransform,
      scratchENUMatrix4
    );
    var rotation = Matrix4.getMatrix3(transform, scratchHPRMatrix3);
    return Quaternion.fromRotationMatrix(rotation, result);
  };

  var noScale = new Cartesian3(1.0, 1.0, 1.0);
  var hprCenterScratch = new Cartesian3();
  var ffScratch = new Matrix4();
  var hprTransformScratch = new Matrix4();
  var hprRotationScratch = new Matrix3();
  var hprQuaternionScratch = new Quaternion();
  /**
   * Computes heading-pitch-roll angles from a transform in a particular reference frame. Heading is the rotation from the local north
   * direction where a positive angle is increasing eastward. Pitch is the rotation from the local east-north plane. Positive pitch angles
   * are above the plane. Negative pitch angles are below the plane. Roll is the first rotation applied about the local east axis.
   *
   * @param {Matrix4} transform The transform
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Transforms.LocalFrameToFixedFrame} [fixedFrameTransform=Transforms.eastNorthUpToFixedFrame] A 4x4 transformation
   *  matrix from a reference frame to the provided ellipsoid's fixed reference frame
   * @param {HeadingPitchRoll} [result] The object onto which to store the result.
   * @returns {HeadingPitchRoll} The modified result parameter or a new HeadingPitchRoll instance if none was provided.
   */
  Transforms.fixedFrameToHeadingPitchRoll = function (
    transform,
    ellipsoid,
    fixedFrameTransform,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("transform", transform);
    //>>includeEnd('debug');

    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    fixedFrameTransform = defaultValue(
      fixedFrameTransform,
      Transforms.eastNorthUpToFixedFrame
    );
    if (!defined(result)) {
      result = new HeadingPitchRoll();
    }

    var center = Matrix4.getTranslation(transform, hprCenterScratch);
    if (Cartesian3.equals(center, Cartesian3.ZERO)) {
      result.heading = 0;
      result.pitch = 0;
      result.roll = 0;
      return result;
    }
    var toFixedFrame = Matrix4.inverseTransformation(
      fixedFrameTransform(center, ellipsoid, ffScratch),
      ffScratch
    );
    var transformCopy = Matrix4.setScale(transform, noScale, hprTransformScratch);
    transformCopy = Matrix4.setTranslation(
      transformCopy,
      Cartesian3.ZERO,
      transformCopy
    );

    toFixedFrame = Matrix4.multiply(toFixedFrame, transformCopy, toFixedFrame);
    var quaternionRotation = Quaternion.fromRotationMatrix(
      Matrix4.getMatrix3(toFixedFrame, hprRotationScratch),
      hprQuaternionScratch
    );
    quaternionRotation = Quaternion.normalize(
      quaternionRotation,
      quaternionRotation
    );

    return HeadingPitchRoll.fromQuaternion(quaternionRotation, result);
  };

  var gmstConstant0 = 6 * 3600 + 41 * 60 + 50.54841;
  var gmstConstant1 = 8640184.812866;
  var gmstConstant2 = 0.093104;
  var gmstConstant3 = -6.2e-6;
  var rateCoef = 1.1772758384668e-19;
  var wgs84WRPrecessing = 7.2921158553e-5;
  var twoPiOverSecondsInDay = CesiumMath.TWO_PI / 86400.0;
  var dateInUtc = new JulianDate();

  /**
   * Computes a rotation matrix to transform a point or vector from True Equator Mean Equinox (TEME) axes to the
   * pseudo-fixed axes at a given time.  This method treats the UT1 time standard as equivalent to UTC.
   *
   * @param {JulianDate} date The time at which to compute the rotation matrix.
   * @param {Matrix3} [result] The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if none was provided.
   *
   * @example
   * //Set the view to the inertial frame.
   * scene.postUpdate.addEventListener(function(scene, time) {
   *    var now = Cesium.JulianDate.now();
   *    var offset = Cesium.Matrix4.multiplyByPoint(camera.transform, camera.position, new Cesium.Cartesian3());
   *    var transform = Cesium.Matrix4.fromRotationTranslation(Cesium.Transforms.computeTemeToPseudoFixedMatrix(now));
   *    var inverseTransform = Cesium.Matrix4.inverseTransformation(transform, new Cesium.Matrix4());
   *    Cesium.Matrix4.multiplyByPoint(inverseTransform, offset, offset);
   *    camera.lookAtTransform(transform, offset);
   * });
   */
  Transforms.computeTemeToPseudoFixedMatrix = function (date, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(date)) {
      throw new DeveloperError("date is required.");
    }
    //>>includeEnd('debug');

    // GMST is actually computed using UT1.  We're using UTC as an approximation of UT1.
    // We do not want to use the function like convertTaiToUtc in JulianDate because
    // we explicitly do not want to fail when inside the leap second.

    dateInUtc = JulianDate.addSeconds(
      date,
      -JulianDate.computeTaiMinusUtc(date),
      dateInUtc
    );
    var utcDayNumber = dateInUtc.dayNumber;
    var utcSecondsIntoDay = dateInUtc.secondsOfDay;

    var t;
    var diffDays = utcDayNumber - 2451545;
    if (utcSecondsIntoDay >= 43200.0) {
      t = (diffDays + 0.5) / TimeConstants$1.DAYS_PER_JULIAN_CENTURY;
    } else {
      t = (diffDays - 0.5) / TimeConstants$1.DAYS_PER_JULIAN_CENTURY;
    }

    var gmst0 =
      gmstConstant0 +
      t * (gmstConstant1 + t * (gmstConstant2 + t * gmstConstant3));
    var angle = (gmst0 * twoPiOverSecondsInDay) % CesiumMath.TWO_PI;
    var ratio = wgs84WRPrecessing + rateCoef * (utcDayNumber - 2451545.5);
    var secondsSinceMidnight =
      (utcSecondsIntoDay + TimeConstants$1.SECONDS_PER_DAY * 0.5) %
      TimeConstants$1.SECONDS_PER_DAY;
    var gha = angle + ratio * secondsSinceMidnight;
    var cosGha = Math.cos(gha);
    var sinGha = Math.sin(gha);

    if (!defined(result)) {
      return new Matrix3(
        cosGha,
        sinGha,
        0.0,
        -sinGha,
        cosGha,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }
    result[0] = cosGha;
    result[1] = -sinGha;
    result[2] = 0.0;
    result[3] = sinGha;
    result[4] = cosGha;
    result[5] = 0.0;
    result[6] = 0.0;
    result[7] = 0.0;
    result[8] = 1.0;
    return result;
  };

  /**
   * The source of IAU 2006 XYS data, used for computing the transformation between the
   * Fixed and ICRF axes.
   * @type {Iau2006XysData}
   *
   * @see Transforms.computeIcrfToFixedMatrix
   * @see Transforms.computeFixedToIcrfMatrix
   *
   * @private
   */
  Transforms.iau2006XysData = new Iau2006XysData();

  /**
   * The source of Earth Orientation Parameters (EOP) data, used for computing the transformation
   * between the Fixed and ICRF axes.  By default, zero values are used for all EOP values,
   * yielding a reasonable but not completely accurate representation of the ICRF axes.
   * @type {EarthOrientationParameters}
   *
   * @see Transforms.computeIcrfToFixedMatrix
   * @see Transforms.computeFixedToIcrfMatrix
   *
   * @private
   */
  Transforms.earthOrientationParameters = EarthOrientationParameters.NONE;

  var ttMinusTai = 32.184;
  var j2000ttDays = 2451545.0;

  /**
   * Preloads the data necessary to transform between the ICRF and Fixed axes, in either
   * direction, over a given interval.  This function returns a promise that, when resolved,
   * indicates that the preload has completed.
   *
   * @param {TimeInterval} timeInterval The interval to preload.
   * @returns {Promise<void>} A promise that, when resolved, indicates that the preload has completed
   *          and evaluation of the transformation between the fixed and ICRF axes will
   *          no longer return undefined for a time inside the interval.
   *
   *
   * @example
   * var interval = new Cesium.TimeInterval(...);
   * when(Cesium.Transforms.preloadIcrfFixed(interval), function() {
   *     // the data is now loaded
   * });
   *
   * @see Transforms.computeIcrfToFixedMatrix
   * @see Transforms.computeFixedToIcrfMatrix
   * @see when
   */
  Transforms.preloadIcrfFixed = function (timeInterval) {
    var startDayTT = timeInterval.start.dayNumber;
    var startSecondTT = timeInterval.start.secondsOfDay + ttMinusTai;
    var stopDayTT = timeInterval.stop.dayNumber;
    var stopSecondTT = timeInterval.stop.secondsOfDay + ttMinusTai;

    var xysPromise = Transforms.iau2006XysData.preload(
      startDayTT,
      startSecondTT,
      stopDayTT,
      stopSecondTT
    );
    var eopPromise = Transforms.earthOrientationParameters.getPromiseToLoad();

    return when.all([xysPromise, eopPromise]);
  };

  /**
   * Computes a rotation matrix to transform a point or vector from the International Celestial
   * Reference Frame (GCRF/ICRF) inertial frame axes to the Earth-Fixed frame axes (ITRF)
   * at a given time.  This function may return undefined if the data necessary to
   * do the transformation is not yet loaded.
   *
   * @param {JulianDate} date The time at which to compute the rotation matrix.
   * @param {Matrix3} [result] The object onto which to store the result.  If this parameter is
   *                  not specified, a new instance is created and returned.
   * @returns {Matrix3} The rotation matrix, or undefined if the data necessary to do the
   *                   transformation is not yet loaded.
   *
   *
   * @example
   * scene.postUpdate.addEventListener(function(scene, time) {
   *   // View in ICRF.
   *   var icrfToFixed = Cesium.Transforms.computeIcrfToFixedMatrix(time);
   *   if (Cesium.defined(icrfToFixed)) {
   *     var offset = Cesium.Cartesian3.clone(camera.position);
   *     var transform = Cesium.Matrix4.fromRotationTranslation(icrfToFixed);
   *     camera.lookAtTransform(transform, offset);
   *   }
   * });
   *
   * @see Transforms.preloadIcrfFixed
   */
  Transforms.computeIcrfToFixedMatrix = function (date, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(date)) {
      throw new DeveloperError("date is required.");
    }
    //>>includeEnd('debug');
    if (!defined(result)) {
      result = new Matrix3();
    }

    var fixedToIcrfMtx = Transforms.computeFixedToIcrfMatrix(date, result);
    if (!defined(fixedToIcrfMtx)) {
      return undefined;
    }

    return Matrix3.transpose(fixedToIcrfMtx, result);
  };

  var xysScratch = new Iau2006XysSample(0.0, 0.0, 0.0);
  var eopScratch = new EarthOrientationParametersSample(
    0.0,
    0.0,
    0.0,
    0.0,
    0.0,
    0.0
  );
  var rotation1Scratch = new Matrix3();
  var rotation2Scratch = new Matrix3();

  /**
   * Computes a rotation matrix to transform a point or vector from the Earth-Fixed frame axes (ITRF)
   * to the International Celestial Reference Frame (GCRF/ICRF) inertial frame axes
   * at a given time.  This function may return undefined if the data necessary to
   * do the transformation is not yet loaded.
   *
   * @param {JulianDate} date The time at which to compute the rotation matrix.
   * @param {Matrix3} [result] The object onto which to store the result.  If this parameter is
   *                  not specified, a new instance is created and returned.
   * @returns {Matrix3} The rotation matrix, or undefined if the data necessary to do the
   *                   transformation is not yet loaded.
   *
   *
   * @example
   * // Transform a point from the ICRF axes to the Fixed axes.
   * var now = Cesium.JulianDate.now();
   * var pointInFixed = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var fixedToIcrf = Cesium.Transforms.computeIcrfToFixedMatrix(now);
   * var pointInInertial = new Cesium.Cartesian3();
   * if (Cesium.defined(fixedToIcrf)) {
   *     pointInInertial = Cesium.Matrix3.multiplyByVector(fixedToIcrf, pointInFixed, pointInInertial);
   * }
   *
   * @see Transforms.preloadIcrfFixed
   */
  Transforms.computeFixedToIcrfMatrix = function (date, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(date)) {
      throw new DeveloperError("date is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Matrix3();
    }

    // Compute pole wander
    var eop = Transforms.earthOrientationParameters.compute(date, eopScratch);
    if (!defined(eop)) {
      return undefined;
    }

    // There is no external conversion to Terrestrial Time (TT).
    // So use International Atomic Time (TAI) and convert using offsets.
    // Here we are assuming that dayTT and secondTT are positive
    var dayTT = date.dayNumber;
    // It's possible here that secondTT could roll over 86400
    // This does not seem to affect the precision (unit tests check for this)
    var secondTT = date.secondsOfDay + ttMinusTai;

    var xys = Transforms.iau2006XysData.computeXysRadians(
      dayTT,
      secondTT,
      xysScratch
    );
    if (!defined(xys)) {
      return undefined;
    }

    var x = xys.x + eop.xPoleOffset;
    var y = xys.y + eop.yPoleOffset;

    // Compute XYS rotation
    var a = 1.0 / (1.0 + Math.sqrt(1.0 - x * x - y * y));

    var rotation1 = rotation1Scratch;
    rotation1[0] = 1.0 - a * x * x;
    rotation1[3] = -a * x * y;
    rotation1[6] = x;
    rotation1[1] = -a * x * y;
    rotation1[4] = 1 - a * y * y;
    rotation1[7] = y;
    rotation1[2] = -x;
    rotation1[5] = -y;
    rotation1[8] = 1 - a * (x * x + y * y);

    var rotation2 = Matrix3.fromRotationZ(-xys.s, rotation2Scratch);
    var matrixQ = Matrix3.multiply(rotation1, rotation2, rotation1Scratch);

    // Similar to TT conversions above
    // It's possible here that secondTT could roll over 86400
    // This does not seem to affect the precision (unit tests check for this)
    var dateUt1day = date.dayNumber;
    var dateUt1sec =
      date.secondsOfDay - JulianDate.computeTaiMinusUtc(date) + eop.ut1MinusUtc;

    // Compute Earth rotation angle
    // The IERS standard for era is
    //    era = 0.7790572732640 + 1.00273781191135448 * Tu
    // where
    //    Tu = JulianDateInUt1 - 2451545.0
    // However, you get much more precision if you make the following simplification
    //    era = a + (1 + b) * (JulianDayNumber + FractionOfDay - 2451545)
    //    era = a + (JulianDayNumber - 2451545) + FractionOfDay + b (JulianDayNumber - 2451545 + FractionOfDay)
    //    era = a + FractionOfDay + b (JulianDayNumber - 2451545 + FractionOfDay)
    // since (JulianDayNumber - 2451545) represents an integer number of revolutions which will be discarded anyway.
    var daysSinceJ2000 = dateUt1day - 2451545;
    var fractionOfDay = dateUt1sec / TimeConstants$1.SECONDS_PER_DAY;
    var era =
      0.779057273264 +
      fractionOfDay +
      0.00273781191135448 * (daysSinceJ2000 + fractionOfDay);
    era = (era % 1.0) * CesiumMath.TWO_PI;

    var earthRotation = Matrix3.fromRotationZ(era, rotation2Scratch);

    // pseudoFixed to ICRF
    var pfToIcrf = Matrix3.multiply(matrixQ, earthRotation, rotation1Scratch);

    // Compute pole wander matrix
    var cosxp = Math.cos(eop.xPoleWander);
    var cosyp = Math.cos(eop.yPoleWander);
    var sinxp = Math.sin(eop.xPoleWander);
    var sinyp = Math.sin(eop.yPoleWander);

    var ttt = dayTT - j2000ttDays + secondTT / TimeConstants$1.SECONDS_PER_DAY;
    ttt /= 36525.0;

    // approximate sp value in rad
    var sp = (-47.0e-6 * ttt * CesiumMath.RADIANS_PER_DEGREE) / 3600.0;
    var cossp = Math.cos(sp);
    var sinsp = Math.sin(sp);

    var fToPfMtx = rotation2Scratch;
    fToPfMtx[0] = cosxp * cossp;
    fToPfMtx[1] = cosxp * sinsp;
    fToPfMtx[2] = sinxp;
    fToPfMtx[3] = -cosyp * sinsp + sinyp * sinxp * cossp;
    fToPfMtx[4] = cosyp * cossp + sinyp * sinxp * sinsp;
    fToPfMtx[5] = -sinyp * cosxp;
    fToPfMtx[6] = -sinyp * sinsp - cosyp * sinxp * cossp;
    fToPfMtx[7] = sinyp * cossp - cosyp * sinxp * sinsp;
    fToPfMtx[8] = cosyp * cosxp;

    return Matrix3.multiply(pfToIcrf, fToPfMtx, result);
  };

  var pointToWindowCoordinatesTemp = new Cartesian4();

  /**
   * Transform a point from model coordinates to window coordinates.
   *
   * @param {Matrix4} modelViewProjectionMatrix The 4x4 model-view-projection matrix.
   * @param {Matrix4} viewportTransformation The 4x4 viewport transformation.
   * @param {Cartesian3} point The point to transform.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if none was provided.
   */
  Transforms.pointToWindowCoordinates = function (
    modelViewProjectionMatrix,
    viewportTransformation,
    point,
    result
  ) {
    result = Transforms.pointToGLWindowCoordinates(
      modelViewProjectionMatrix,
      viewportTransformation,
      point,
      result
    );
    result.y = 2.0 * viewportTransformation[5] - result.y;
    return result;
  };

  /**
   * @private
   */
  Transforms.pointToGLWindowCoordinates = function (
    modelViewProjectionMatrix,
    viewportTransformation,
    point,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(modelViewProjectionMatrix)) {
      throw new DeveloperError("modelViewProjectionMatrix is required.");
    }

    if (!defined(viewportTransformation)) {
      throw new DeveloperError("viewportTransformation is required.");
    }

    if (!defined(point)) {
      throw new DeveloperError("point is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian2();
    }

    var tmp = pointToWindowCoordinatesTemp;

    Matrix4.multiplyByVector(
      modelViewProjectionMatrix,
      Cartesian4.fromElements(point.x, point.y, point.z, 1, tmp),
      tmp
    );
    Cartesian4.multiplyByScalar(tmp, 1.0 / tmp.w, tmp);
    Matrix4.multiplyByVector(viewportTransformation, tmp, tmp);
    return Cartesian2.fromCartesian4(tmp, result);
  };

  var normalScratch = new Cartesian3();
  var rightScratch = new Cartesian3();
  var upScratch = new Cartesian3();

  /**
   * Transform a position and velocity to a rotation matrix.
   *
   * @param {Cartesian3} position The position to transform.
   * @param {Cartesian3} velocity The velocity vector to transform.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
   * @param {Matrix3} [result] The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if none was provided.
   */
  Transforms.rotationMatrixFromPositionVelocity = function (
    position,
    velocity,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(position)) {
      throw new DeveloperError("position is required.");
    }

    if (!defined(velocity)) {
      throw new DeveloperError("velocity is required.");
    }
    //>>includeEnd('debug');

    var normal = defaultValue(ellipsoid, Ellipsoid.WGS84).geodeticSurfaceNormal(
      position,
      normalScratch
    );
    var right = Cartesian3.cross(velocity, normal, rightScratch);

    if (Cartesian3.equalsEpsilon(right, Cartesian3.ZERO, CesiumMath.EPSILON6)) {
      right = Cartesian3.clone(Cartesian3.UNIT_X, right);
    }

    var up = Cartesian3.cross(right, velocity, upScratch);
    Cartesian3.normalize(up, up);
    Cartesian3.cross(velocity, up, right);
    Cartesian3.negate(right, right);
    Cartesian3.normalize(right, right);

    if (!defined(result)) {
      result = new Matrix3();
    }

    result[0] = velocity.x;
    result[1] = velocity.y;
    result[2] = velocity.z;
    result[3] = right.x;
    result[4] = right.y;
    result[5] = right.z;
    result[6] = up.x;
    result[7] = up.y;
    result[8] = up.z;

    return result;
  };

  var swizzleMatrix = new Matrix4(
    0.0,
    0.0,
    1.0,
    0.0,
    1.0,
    0.0,
    0.0,
    0.0,
    0.0,
    1.0,
    0.0,
    0.0,
    0.0,
    0.0,
    0.0,
    1.0
  );

  var scratchCartographic = new Cartographic();
  var scratchCartesian3Projection = new Cartesian3();
  var scratchCenter = new Cartesian3();
  var scratchRotation = new Matrix3();
  var scratchFromENU = new Matrix4();
  var scratchToENU = new Matrix4();

  /**
   * @private
   */
  Transforms.basisTo2D = function (projection, matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(projection)) {
      throw new DeveloperError("projection is required.");
    }
    if (!defined(matrix)) {
      throw new DeveloperError("matrix is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var rtcCenter = Matrix4.getTranslation(matrix, scratchCenter);
    var ellipsoid = projection.ellipsoid;

    // Get the 2D Center
    var cartographic = ellipsoid.cartesianToCartographic(
      rtcCenter,
      scratchCartographic
    );
    var projectedPosition = projection.project(
      cartographic,
      scratchCartesian3Projection
    );
    Cartesian3.fromElements(
      projectedPosition.z,
      projectedPosition.x,
      projectedPosition.y,
      projectedPosition
    );

    // Assuming the instance are positioned in WGS84, invert the WGS84 transform to get the local transform and then convert to 2D
    var fromENU = Transforms.eastNorthUpToFixedFrame(
      rtcCenter,
      ellipsoid,
      scratchFromENU
    );
    var toENU = Matrix4.inverseTransformation(fromENU, scratchToENU);
    var rotation = Matrix4.getMatrix3(matrix, scratchRotation);
    var local = Matrix4.multiplyByMatrix3(toENU, rotation, result);
    Matrix4.multiply(swizzleMatrix, local, result); // Swap x, y, z for 2D
    Matrix4.setTranslation(result, projectedPosition, result); // Use the projected center

    return result;
  };

  /**
   * @private
   */
  Transforms.wgs84To2DModelMatrix = function (projection, center, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(projection)) {
      throw new DeveloperError("projection is required.");
    }
    if (!defined(center)) {
      throw new DeveloperError("center is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var ellipsoid = projection.ellipsoid;

    var fromENU = Transforms.eastNorthUpToFixedFrame(
      center,
      ellipsoid,
      scratchFromENU
    );
    var toENU = Matrix4.inverseTransformation(fromENU, scratchToENU);

    var cartographic = ellipsoid.cartesianToCartographic(
      center,
      scratchCartographic
    );
    var projectedPosition = projection.project(
      cartographic,
      scratchCartesian3Projection
    );
    Cartesian3.fromElements(
      projectedPosition.z,
      projectedPosition.x,
      projectedPosition.y,
      projectedPosition
    );

    var translation = Matrix4.fromTranslation(projectedPosition, scratchFromENU);
    Matrix4.multiply(swizzleMatrix, toENU, result);
    Matrix4.multiply(translation, result, result);

    return result;
  };

  var scratchCart4 = new Cartesian4();
  /**
   * A plane tangent to the provided ellipsoid at the provided origin.
   * If origin is not on the surface of the ellipsoid, it's surface projection will be used.
   * If origin is at the center of the ellipsoid, an exception will be thrown.
   * @alias EllipsoidTangentPlane
   * @constructor
   *
   * @param {Cartesian3} origin The point on the surface of the ellipsoid where the tangent plane touches.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid to use.
   *
   * @exception {DeveloperError} origin must not be at the center of the ellipsoid.
   */
  function EllipsoidTangentPlane(origin, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("origin", origin);
    //>>includeEnd('debug');

    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    origin = ellipsoid.scaleToGeodeticSurface(origin);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(origin)) {
      throw new DeveloperError(
        "origin must not be at the center of the ellipsoid."
      );
    }
    //>>includeEnd('debug');

    var eastNorthUp = Transforms.eastNorthUpToFixedFrame(origin, ellipsoid);
    this._ellipsoid = ellipsoid;
    this._origin = origin;
    this._xAxis = Cartesian3.fromCartesian4(
      Matrix4.getColumn(eastNorthUp, 0, scratchCart4)
    );
    this._yAxis = Cartesian3.fromCartesian4(
      Matrix4.getColumn(eastNorthUp, 1, scratchCart4)
    );

    var normal = Cartesian3.fromCartesian4(
      Matrix4.getColumn(eastNorthUp, 2, scratchCart4)
    );
    this._plane = Plane.fromPointNormal(origin, normal);
  }

  Object.defineProperties(EllipsoidTangentPlane.prototype, {
    /**
     * Gets the ellipsoid.
     * @memberof EllipsoidTangentPlane.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },

    /**
     * Gets the origin.
     * @memberof EllipsoidTangentPlane.prototype
     * @type {Cartesian3}
     */
    origin: {
      get: function () {
        return this._origin;
      },
    },

    /**
     * Gets the plane which is tangent to the ellipsoid.
     * @memberof EllipsoidTangentPlane.prototype
     * @readonly
     * @type {Plane}
     */
    plane: {
      get: function () {
        return this._plane;
      },
    },

    /**
     * Gets the local X-axis (east) of the tangent plane.
     * @memberof EllipsoidTangentPlane.prototype
     * @readonly
     * @type {Cartesian3}
     */
    xAxis: {
      get: function () {
        return this._xAxis;
      },
    },

    /**
     * Gets the local Y-axis (north) of the tangent plane.
     * @memberof EllipsoidTangentPlane.prototype
     * @readonly
     * @type {Cartesian3}
     */
    yAxis: {
      get: function () {
        return this._yAxis;
      },
    },

    /**
     * Gets the local Z-axis (up) of the tangent plane.
     * @memberof EllipsoidTangentPlane.prototype
     * @readonly
     * @type {Cartesian3}
     */
    zAxis: {
      get: function () {
        return this._plane.normal;
      },
    },
  });

  var tmp = new AxisAlignedBoundingBox();
  /**
   * Creates a new instance from the provided ellipsoid and the center
   * point of the provided Cartesians.
   *
   * @param {Cartesian3[]} cartesians The list of positions surrounding the center point.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid to use.
   */
  EllipsoidTangentPlane.fromPoints = function (cartesians, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    //>>includeEnd('debug');

    var box = AxisAlignedBoundingBox.fromPoints(cartesians, tmp);
    return new EllipsoidTangentPlane(box.center, ellipsoid);
  };

  var scratchProjectPointOntoPlaneRay = new Ray();
  var scratchProjectPointOntoPlaneCartesian3 = new Cartesian3();

  /**
   * Computes the projection of the provided 3D position onto the 2D plane, radially outward from the {@link EllipsoidTangentPlane.ellipsoid} coordinate system origin.
   *
   * @param {Cartesian3} cartesian The point to project.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if none was provided. Undefined if there is no intersection point
   */
  EllipsoidTangentPlane.prototype.projectPointOntoPlane = function (
    cartesian,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesian", cartesian);
    //>>includeEnd('debug');

    var ray = scratchProjectPointOntoPlaneRay;
    ray.origin = cartesian;
    Cartesian3.normalize(cartesian, ray.direction);

    var intersectionPoint = IntersectionTests.rayPlane(
      ray,
      this._plane,
      scratchProjectPointOntoPlaneCartesian3
    );
    if (!defined(intersectionPoint)) {
      Cartesian3.negate(ray.direction, ray.direction);
      intersectionPoint = IntersectionTests.rayPlane(
        ray,
        this._plane,
        scratchProjectPointOntoPlaneCartesian3
      );
    }

    if (defined(intersectionPoint)) {
      var v = Cartesian3.subtract(
        intersectionPoint,
        this._origin,
        intersectionPoint
      );
      var x = Cartesian3.dot(this._xAxis, v);
      var y = Cartesian3.dot(this._yAxis, v);

      if (!defined(result)) {
        return new Cartesian2(x, y);
      }
      result.x = x;
      result.y = y;
      return result;
    }
    return undefined;
  };

  /**
   * Computes the projection of the provided 3D positions onto the 2D plane (where possible), radially outward from the global origin.
   * The resulting array may be shorter than the input array - if a single projection is impossible it will not be included.
   *
   * @see EllipsoidTangentPlane.projectPointOntoPlane
   *
   * @param {Cartesian3[]} cartesians The array of points to project.
   * @param {Cartesian2[]} [result] The array of Cartesian2 instances onto which to store results.
   * @returns {Cartesian2[]} The modified result parameter or a new array of Cartesian2 instances if none was provided.
   */
  EllipsoidTangentPlane.prototype.projectPointsOntoPlane = function (
    cartesians,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = [];
    }

    var count = 0;
    var length = cartesians.length;
    for (var i = 0; i < length; i++) {
      var p = this.projectPointOntoPlane(cartesians[i], result[count]);
      if (defined(p)) {
        result[count] = p;
        count++;
      }
    }
    result.length = count;
    return result;
  };

  /**
   * Computes the projection of the provided 3D position onto the 2D plane, along the plane normal.
   *
   * @param {Cartesian3} cartesian The point to project.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if none was provided.
   */
  EllipsoidTangentPlane.prototype.projectPointToNearestOnPlane = function (
    cartesian,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesian", cartesian);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian2();
    }

    var ray = scratchProjectPointOntoPlaneRay;
    ray.origin = cartesian;
    Cartesian3.clone(this._plane.normal, ray.direction);

    var intersectionPoint = IntersectionTests.rayPlane(
      ray,
      this._plane,
      scratchProjectPointOntoPlaneCartesian3
    );
    if (!defined(intersectionPoint)) {
      Cartesian3.negate(ray.direction, ray.direction);
      intersectionPoint = IntersectionTests.rayPlane(
        ray,
        this._plane,
        scratchProjectPointOntoPlaneCartesian3
      );
    }

    var v = Cartesian3.subtract(
      intersectionPoint,
      this._origin,
      intersectionPoint
    );
    var x = Cartesian3.dot(this._xAxis, v);
    var y = Cartesian3.dot(this._yAxis, v);

    result.x = x;
    result.y = y;
    return result;
  };

  /**
   * Computes the projection of the provided 3D positions onto the 2D plane, along the plane normal.
   *
   * @see EllipsoidTangentPlane.projectPointToNearestOnPlane
   *
   * @param {Cartesian3[]} cartesians The array of points to project.
   * @param {Cartesian2[]} [result] The array of Cartesian2 instances onto which to store results.
   * @returns {Cartesian2[]} The modified result parameter or a new array of Cartesian2 instances if none was provided. This will have the same length as <code>cartesians</code>.
   */
  EllipsoidTangentPlane.prototype.projectPointsToNearestOnPlane = function (
    cartesians,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = [];
    }

    var length = cartesians.length;
    result.length = length;
    for (var i = 0; i < length; i++) {
      result[i] = this.projectPointToNearestOnPlane(cartesians[i], result[i]);
    }
    return result;
  };

  var projectPointsOntoEllipsoidScratch = new Cartesian3();
  /**
   * Computes the projection of the provided 2D position onto the 3D ellipsoid.
   *
   * @param {Cartesian2} cartesian The points to project.
   * @param {Cartesian3} [result] The Cartesian3 instance to store result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if none was provided.
   */
  EllipsoidTangentPlane.prototype.projectPointOntoEllipsoid = function (
    cartesian,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesian", cartesian);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    var ellipsoid = this._ellipsoid;
    var origin = this._origin;
    var xAxis = this._xAxis;
    var yAxis = this._yAxis;
    var tmp = projectPointsOntoEllipsoidScratch;

    Cartesian3.multiplyByScalar(xAxis, cartesian.x, tmp);
    result = Cartesian3.add(origin, tmp, result);
    Cartesian3.multiplyByScalar(yAxis, cartesian.y, tmp);
    Cartesian3.add(result, tmp, result);
    ellipsoid.scaleToGeocentricSurface(result, result);

    return result;
  };

  /**
   * Computes the projection of the provided 2D positions onto the 3D ellipsoid.
   *
   * @param {Cartesian2[]} cartesians The array of points to project.
   * @param {Cartesian3[]} [result] The array of Cartesian3 instances onto which to store results.
   * @returns {Cartesian3[]} The modified result parameter or a new array of Cartesian3 instances if none was provided.
   */
  EllipsoidTangentPlane.prototype.projectPointsOntoEllipsoid = function (
    cartesians,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    //>>includeEnd('debug');

    var length = cartesians.length;
    if (!defined(result)) {
      result = new Array(length);
    } else {
      result.length = length;
    }

    for (var i = 0; i < length; ++i) {
      result[i] = this.projectPointOntoEllipsoid(cartesians[i], result[i]);
    }

    return result;
  };

  /**
   * Creates an instance of an OrientedBoundingBox.
   * An OrientedBoundingBox of some object is a closed and convex cuboid. It can provide a tighter bounding volume than {@link BoundingSphere} or {@link AxisAlignedBoundingBox} in many cases.
   * @alias OrientedBoundingBox
   * @constructor
   *
   * @param {Cartesian3} [center=Cartesian3.ZERO] The center of the box.
   * @param {Matrix3} [halfAxes=Matrix3.ZERO] The three orthogonal half-axes of the bounding box.
   *                                          Equivalently, the transformation matrix, to rotate and scale a 0x0x0
   *                                          cube centered at the origin.
   *
   *
   * @example
   * // Create an OrientedBoundingBox using a transformation matrix, a position where the box will be translated, and a scale.
   * var center = new Cesium.Cartesian3(1.0, 0.0, 0.0);
   * var halfAxes = Cesium.Matrix3.fromScale(new Cesium.Cartesian3(1.0, 3.0, 2.0), new Cesium.Matrix3());
   *
   * var obb = new Cesium.OrientedBoundingBox(center, halfAxes);
   *
   * @see BoundingSphere
   * @see BoundingRectangle
   */
  function OrientedBoundingBox(center, halfAxes) {
    /**
     * The center of the box.
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.center = Cartesian3.clone(defaultValue(center, Cartesian3.ZERO));
    /**
     * The transformation matrix, to rotate the box to the right position.
     * @type {Matrix3}
     * @default {@link Matrix3.ZERO}
     */
    this.halfAxes = Matrix3.clone(defaultValue(halfAxes, Matrix3.ZERO));
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  OrientedBoundingBox.packedLength =
    Cartesian3.packedLength + Matrix3.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {OrientedBoundingBox} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  OrientedBoundingBox.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value.center, array, startingIndex);
    Matrix3.pack(value.halfAxes, array, startingIndex + Cartesian3.packedLength);

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {OrientedBoundingBox} [result] The object into which to store the result.
   * @returns {OrientedBoundingBox} The modified result parameter or a new OrientedBoundingBox instance if one was not provided.
   */
  OrientedBoundingBox.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new OrientedBoundingBox();
    }

    Cartesian3.unpack(array, startingIndex, result.center);
    Matrix3.unpack(
      array,
      startingIndex + Cartesian3.packedLength,
      result.halfAxes
    );
    return result;
  };

  var scratchCartesian1 = new Cartesian3();
  var scratchCartesian2 = new Cartesian3();
  var scratchCartesian3$1 = new Cartesian3();
  var scratchCartesian4 = new Cartesian3();
  var scratchCartesian5 = new Cartesian3();
  var scratchCartesian6 = new Cartesian3();
  var scratchCovarianceResult = new Matrix3();
  var scratchEigenResult = {
    unitary: new Matrix3(),
    diagonal: new Matrix3(),
  };

  /**
   * Computes an instance of an OrientedBoundingBox of the given positions.
   * This is an implementation of Stefan Gottschalk's Collision Queries using Oriented Bounding Boxes solution (PHD thesis).
   * Reference: http://gamma.cs.unc.edu/users/gottschalk/main.pdf
   *
   * @param {Cartesian3[]} [positions] List of {@link Cartesian3} points that the bounding box will enclose.
   * @param {OrientedBoundingBox} [result] The object onto which to store the result.
   * @returns {OrientedBoundingBox} The modified result parameter or a new OrientedBoundingBox instance if one was not provided.
   *
   * @example
   * // Compute an object oriented bounding box enclosing two points.
   * var box = Cesium.OrientedBoundingBox.fromPoints([new Cesium.Cartesian3(2, 0, 0), new Cesium.Cartesian3(-2, 0, 0)]);
   */
  OrientedBoundingBox.fromPoints = function (positions, result) {
    if (!defined(result)) {
      result = new OrientedBoundingBox();
    }

    if (!defined(positions) || positions.length === 0) {
      result.halfAxes = Matrix3.ZERO;
      result.center = Cartesian3.ZERO;
      return result;
    }

    var i;
    var length = positions.length;

    var meanPoint = Cartesian3.clone(positions[0], scratchCartesian1);
    for (i = 1; i < length; i++) {
      Cartesian3.add(meanPoint, positions[i], meanPoint);
    }
    var invLength = 1.0 / length;
    Cartesian3.multiplyByScalar(meanPoint, invLength, meanPoint);

    var exx = 0.0;
    var exy = 0.0;
    var exz = 0.0;
    var eyy = 0.0;
    var eyz = 0.0;
    var ezz = 0.0;
    var p;

    for (i = 0; i < length; i++) {
      p = Cartesian3.subtract(positions[i], meanPoint, scratchCartesian2);
      exx += p.x * p.x;
      exy += p.x * p.y;
      exz += p.x * p.z;
      eyy += p.y * p.y;
      eyz += p.y * p.z;
      ezz += p.z * p.z;
    }

    exx *= invLength;
    exy *= invLength;
    exz *= invLength;
    eyy *= invLength;
    eyz *= invLength;
    ezz *= invLength;

    var covarianceMatrix = scratchCovarianceResult;
    covarianceMatrix[0] = exx;
    covarianceMatrix[1] = exy;
    covarianceMatrix[2] = exz;
    covarianceMatrix[3] = exy;
    covarianceMatrix[4] = eyy;
    covarianceMatrix[5] = eyz;
    covarianceMatrix[6] = exz;
    covarianceMatrix[7] = eyz;
    covarianceMatrix[8] = ezz;

    var eigenDecomposition = Matrix3.computeEigenDecomposition(
      covarianceMatrix,
      scratchEigenResult
    );
    var rotation = Matrix3.clone(eigenDecomposition.unitary, result.halfAxes);

    var v1 = Matrix3.getColumn(rotation, 0, scratchCartesian4);
    var v2 = Matrix3.getColumn(rotation, 1, scratchCartesian5);
    var v3 = Matrix3.getColumn(rotation, 2, scratchCartesian6);

    var u1 = -Number.MAX_VALUE;
    var u2 = -Number.MAX_VALUE;
    var u3 = -Number.MAX_VALUE;
    var l1 = Number.MAX_VALUE;
    var l2 = Number.MAX_VALUE;
    var l3 = Number.MAX_VALUE;

    for (i = 0; i < length; i++) {
      p = positions[i];
      u1 = Math.max(Cartesian3.dot(v1, p), u1);
      u2 = Math.max(Cartesian3.dot(v2, p), u2);
      u3 = Math.max(Cartesian3.dot(v3, p), u3);

      l1 = Math.min(Cartesian3.dot(v1, p), l1);
      l2 = Math.min(Cartesian3.dot(v2, p), l2);
      l3 = Math.min(Cartesian3.dot(v3, p), l3);
    }

    v1 = Cartesian3.multiplyByScalar(v1, 0.5 * (l1 + u1), v1);
    v2 = Cartesian3.multiplyByScalar(v2, 0.5 * (l2 + u2), v2);
    v3 = Cartesian3.multiplyByScalar(v3, 0.5 * (l3 + u3), v3);

    var center = Cartesian3.add(v1, v2, result.center);
    Cartesian3.add(center, v3, center);

    var scale = scratchCartesian3$1;
    scale.x = u1 - l1;
    scale.y = u2 - l2;
    scale.z = u3 - l3;
    Cartesian3.multiplyByScalar(scale, 0.5, scale);
    Matrix3.multiplyByScale(result.halfAxes, scale, result.halfAxes);

    return result;
  };

  var scratchOffset = new Cartesian3();
  var scratchScale$3 = new Cartesian3();
  function fromPlaneExtents(
    planeOrigin,
    planeXAxis,
    planeYAxis,
    planeZAxis,
    minimumX,
    maximumX,
    minimumY,
    maximumY,
    minimumZ,
    maximumZ,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(minimumX) ||
      !defined(maximumX) ||
      !defined(minimumY) ||
      !defined(maximumY) ||
      !defined(minimumZ) ||
      !defined(maximumZ)
    ) {
      throw new DeveloperError(
        "all extents (minimum/maximum X/Y/Z) are required."
      );
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new OrientedBoundingBox();
    }

    var halfAxes = result.halfAxes;
    Matrix3.setColumn(halfAxes, 0, planeXAxis, halfAxes);
    Matrix3.setColumn(halfAxes, 1, planeYAxis, halfAxes);
    Matrix3.setColumn(halfAxes, 2, planeZAxis, halfAxes);

    var centerOffset = scratchOffset;
    centerOffset.x = (minimumX + maximumX) / 2.0;
    centerOffset.y = (minimumY + maximumY) / 2.0;
    centerOffset.z = (minimumZ + maximumZ) / 2.0;

    var scale = scratchScale$3;
    scale.x = (maximumX - minimumX) / 2.0;
    scale.y = (maximumY - minimumY) / 2.0;
    scale.z = (maximumZ - minimumZ) / 2.0;

    var center = result.center;
    centerOffset = Matrix3.multiplyByVector(halfAxes, centerOffset, centerOffset);
    Cartesian3.add(planeOrigin, centerOffset, center);
    Matrix3.multiplyByScale(halfAxes, scale, halfAxes);

    return result;
  }

  var scratchRectangleCenterCartographic = new Cartographic();
  var scratchRectangleCenter = new Cartesian3();
  var scratchPerimeterCartographicNC = new Cartographic();
  var scratchPerimeterCartographicNW = new Cartographic();
  var scratchPerimeterCartographicCW = new Cartographic();
  var scratchPerimeterCartographicSW = new Cartographic();
  var scratchPerimeterCartographicSC = new Cartographic();
  var scratchPerimeterCartesianNC = new Cartesian3();
  var scratchPerimeterCartesianNW = new Cartesian3();
  var scratchPerimeterCartesianCW = new Cartesian3();
  var scratchPerimeterCartesianSW = new Cartesian3();
  var scratchPerimeterCartesianSC = new Cartesian3();
  var scratchPerimeterProjectedNC = new Cartesian2();
  var scratchPerimeterProjectedNW = new Cartesian2();
  var scratchPerimeterProjectedCW = new Cartesian2();
  var scratchPerimeterProjectedSW = new Cartesian2();
  var scratchPerimeterProjectedSC = new Cartesian2();

  var scratchPlaneOrigin = new Cartesian3();
  var scratchPlaneNormal = new Cartesian3();
  var scratchPlaneXAxis = new Cartesian3();
  var scratchHorizonCartesian = new Cartesian3();
  var scratchHorizonProjected = new Cartesian2();
  var scratchMaxY = new Cartesian3();
  var scratchMinY = new Cartesian3();
  var scratchZ = new Cartesian3();
  var scratchPlane = new Plane(Cartesian3.UNIT_X, 0.0);

  /**
   * Computes an OrientedBoundingBox that bounds a {@link Rectangle} on the surface of an {@link Ellipsoid}.
   * There are no guarantees about the orientation of the bounding box.
   *
   * @param {Rectangle} rectangle The cartographic rectangle on the surface of the ellipsoid.
   * @param {Number} [minimumHeight=0.0] The minimum height (elevation) within the tile.
   * @param {Number} [maximumHeight=0.0] The maximum height (elevation) within the tile.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the rectangle is defined.
   * @param {OrientedBoundingBox} [result] The object onto which to store the result.
   * @returns {OrientedBoundingBox} The modified result parameter or a new OrientedBoundingBox instance if none was provided.
   *
   * @exception {DeveloperError} rectangle.width must be between 0 and pi.
   * @exception {DeveloperError} rectangle.height must be between 0 and pi.
   * @exception {DeveloperError} ellipsoid must be an ellipsoid of revolution (<code>radii.x == radii.y</code>)
   */
  OrientedBoundingBox.fromRectangle = function (
    rectangle,
    minimumHeight,
    maximumHeight,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(rectangle)) {
      throw new DeveloperError("rectangle is required");
    }
    if (rectangle.width < 0.0 || rectangle.width > CesiumMath.TWO_PI) {
      throw new DeveloperError("Rectangle width must be between 0 and 2*pi");
    }
    if (rectangle.height < 0.0 || rectangle.height > CesiumMath.PI) {
      throw new DeveloperError("Rectangle height must be between 0 and pi");
    }
    if (
      defined(ellipsoid) &&
      !CesiumMath.equalsEpsilon(
        ellipsoid.radii.x,
        ellipsoid.radii.y,
        CesiumMath.EPSILON15
      )
    ) {
      throw new DeveloperError(
        "Ellipsoid must be an ellipsoid of revolution (radii.x == radii.y)"
      );
    }
    //>>includeEnd('debug');

    minimumHeight = defaultValue(minimumHeight, 0.0);
    maximumHeight = defaultValue(maximumHeight, 0.0);
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var minX, maxX, minY, maxY, minZ, maxZ, plane;

    if (rectangle.width <= CesiumMath.PI) {
      // The bounding box will be aligned with the tangent plane at the center of the rectangle.
      var tangentPointCartographic = Rectangle.center(
        rectangle,
        scratchRectangleCenterCartographic
      );
      var tangentPoint = ellipsoid.cartographicToCartesian(
        tangentPointCartographic,
        scratchRectangleCenter
      );
      var tangentPlane = new EllipsoidTangentPlane(tangentPoint, ellipsoid);
      plane = tangentPlane.plane;

      // If the rectangle spans the equator, CW is instead aligned with the equator (because it sticks out the farthest at the equator).
      var lonCenter = tangentPointCartographic.longitude;
      var latCenter =
        rectangle.south < 0.0 && rectangle.north > 0.0
          ? 0.0
          : tangentPointCartographic.latitude;

      // Compute XY extents using the rectangle at maximum height
      var perimeterCartographicNC = Cartographic.fromRadians(
        lonCenter,
        rectangle.north,
        maximumHeight,
        scratchPerimeterCartographicNC
      );
      var perimeterCartographicNW = Cartographic.fromRadians(
        rectangle.west,
        rectangle.north,
        maximumHeight,
        scratchPerimeterCartographicNW
      );
      var perimeterCartographicCW = Cartographic.fromRadians(
        rectangle.west,
        latCenter,
        maximumHeight,
        scratchPerimeterCartographicCW
      );
      var perimeterCartographicSW = Cartographic.fromRadians(
        rectangle.west,
        rectangle.south,
        maximumHeight,
        scratchPerimeterCartographicSW
      );
      var perimeterCartographicSC = Cartographic.fromRadians(
        lonCenter,
        rectangle.south,
        maximumHeight,
        scratchPerimeterCartographicSC
      );

      var perimeterCartesianNC = ellipsoid.cartographicToCartesian(
        perimeterCartographicNC,
        scratchPerimeterCartesianNC
      );
      var perimeterCartesianNW = ellipsoid.cartographicToCartesian(
        perimeterCartographicNW,
        scratchPerimeterCartesianNW
      );
      var perimeterCartesianCW = ellipsoid.cartographicToCartesian(
        perimeterCartographicCW,
        scratchPerimeterCartesianCW
      );
      var perimeterCartesianSW = ellipsoid.cartographicToCartesian(
        perimeterCartographicSW,
        scratchPerimeterCartesianSW
      );
      var perimeterCartesianSC = ellipsoid.cartographicToCartesian(
        perimeterCartographicSC,
        scratchPerimeterCartesianSC
      );

      var perimeterProjectedNC = tangentPlane.projectPointToNearestOnPlane(
        perimeterCartesianNC,
        scratchPerimeterProjectedNC
      );
      var perimeterProjectedNW = tangentPlane.projectPointToNearestOnPlane(
        perimeterCartesianNW,
        scratchPerimeterProjectedNW
      );
      var perimeterProjectedCW = tangentPlane.projectPointToNearestOnPlane(
        perimeterCartesianCW,
        scratchPerimeterProjectedCW
      );
      var perimeterProjectedSW = tangentPlane.projectPointToNearestOnPlane(
        perimeterCartesianSW,
        scratchPerimeterProjectedSW
      );
      var perimeterProjectedSC = tangentPlane.projectPointToNearestOnPlane(
        perimeterCartesianSC,
        scratchPerimeterProjectedSC
      );

      minX = Math.min(
        perimeterProjectedNW.x,
        perimeterProjectedCW.x,
        perimeterProjectedSW.x
      );
      maxX = -minX; // symmetrical

      maxY = Math.max(perimeterProjectedNW.y, perimeterProjectedNC.y);
      minY = Math.min(perimeterProjectedSW.y, perimeterProjectedSC.y);

      // Compute minimum Z using the rectangle at minimum height, since it will be deeper than the maximum height
      perimeterCartographicNW.height = perimeterCartographicSW.height = minimumHeight;
      perimeterCartesianNW = ellipsoid.cartographicToCartesian(
        perimeterCartographicNW,
        scratchPerimeterCartesianNW
      );
      perimeterCartesianSW = ellipsoid.cartographicToCartesian(
        perimeterCartographicSW,
        scratchPerimeterCartesianSW
      );

      minZ = Math.min(
        Plane.getPointDistance(plane, perimeterCartesianNW),
        Plane.getPointDistance(plane, perimeterCartesianSW)
      );
      maxZ = maximumHeight; // Since the tangent plane touches the surface at height = 0, this is okay

      return fromPlaneExtents(
        tangentPlane.origin,
        tangentPlane.xAxis,
        tangentPlane.yAxis,
        tangentPlane.zAxis,
        minX,
        maxX,
        minY,
        maxY,
        minZ,
        maxZ,
        result
      );
    }

    // Handle the case where rectangle width is greater than PI (wraps around more than half the ellipsoid).
    var fullyAboveEquator = rectangle.south > 0.0;
    var fullyBelowEquator = rectangle.north < 0.0;
    var latitudeNearestToEquator = fullyAboveEquator
      ? rectangle.south
      : fullyBelowEquator
      ? rectangle.north
      : 0.0;
    var centerLongitude = Rectangle.center(
      rectangle,
      scratchRectangleCenterCartographic
    ).longitude;

    // Plane is located at the rectangle's center longitude and the rectangle's latitude that is closest to the equator. It rotates around the Z axis.
    // This results in a better fit than the obb approach for smaller rectangles, which orients with the rectangle's center normal.
    var planeOrigin = Cartesian3.fromRadians(
      centerLongitude,
      latitudeNearestToEquator,
      maximumHeight,
      ellipsoid,
      scratchPlaneOrigin
    );
    planeOrigin.z = 0.0; // center the plane on the equator to simpify plane normal calculation
    var isPole =
      Math.abs(planeOrigin.x) < CesiumMath.EPSILON10 &&
      Math.abs(planeOrigin.y) < CesiumMath.EPSILON10;
    var planeNormal = !isPole
      ? Cartesian3.normalize(planeOrigin, scratchPlaneNormal)
      : Cartesian3.UNIT_X;
    var planeYAxis = Cartesian3.UNIT_Z;
    var planeXAxis = Cartesian3.cross(planeNormal, planeYAxis, scratchPlaneXAxis);
    plane = Plane.fromPointNormal(planeOrigin, planeNormal, scratchPlane);

    // Get the horizon point relative to the center. This will be the farthest extent in the plane's X dimension.
    var horizonCartesian = Cartesian3.fromRadians(
      centerLongitude + CesiumMath.PI_OVER_TWO,
      latitudeNearestToEquator,
      maximumHeight,
      ellipsoid,
      scratchHorizonCartesian
    );
    maxX = Cartesian3.dot(
      Plane.projectPointOntoPlane(
        plane,
        horizonCartesian,
        scratchHorizonProjected
      ),
      planeXAxis
    );
    minX = -maxX; // symmetrical

    // Get the min and max Y, using the height that will give the largest extent
    maxY = Cartesian3.fromRadians(
      0.0,
      rectangle.north,
      fullyBelowEquator ? minimumHeight : maximumHeight,
      ellipsoid,
      scratchMaxY
    ).z;
    minY = Cartesian3.fromRadians(
      0.0,
      rectangle.south,
      fullyAboveEquator ? minimumHeight : maximumHeight,
      ellipsoid,
      scratchMinY
    ).z;

    var farZ = Cartesian3.fromRadians(
      rectangle.east,
      latitudeNearestToEquator,
      maximumHeight,
      ellipsoid,
      scratchZ
    );
    minZ = Plane.getPointDistance(plane, farZ);
    maxZ = 0.0; // plane origin starts at maxZ already

    // min and max are local to the plane axes
    return fromPlaneExtents(
      planeOrigin,
      planeXAxis,
      planeYAxis,
      planeNormal,
      minX,
      maxX,
      minY,
      maxY,
      minZ,
      maxZ,
      result
    );
  };

  /**
   * Duplicates a OrientedBoundingBox instance.
   *
   * @param {OrientedBoundingBox} box The bounding box to duplicate.
   * @param {OrientedBoundingBox} [result] The object onto which to store the result.
   * @returns {OrientedBoundingBox} The modified result parameter or a new OrientedBoundingBox instance if none was provided. (Returns undefined if box is undefined)
   */
  OrientedBoundingBox.clone = function (box, result) {
    if (!defined(box)) {
      return undefined;
    }

    if (!defined(result)) {
      return new OrientedBoundingBox(box.center, box.halfAxes);
    }

    Cartesian3.clone(box.center, result.center);
    Matrix3.clone(box.halfAxes, result.halfAxes);

    return result;
  };

  /**
   * Determines which side of a plane the oriented bounding box is located.
   *
   * @param {OrientedBoundingBox} box The oriented bounding box to test.
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
   *                      intersects the plane.
   */
  OrientedBoundingBox.intersectPlane = function (box, plane) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(box)) {
      throw new DeveloperError("box is required.");
    }

    if (!defined(plane)) {
      throw new DeveloperError("plane is required.");
    }
    //>>includeEnd('debug');

    var center = box.center;
    var normal = plane.normal;
    var halfAxes = box.halfAxes;
    var normalX = normal.x,
      normalY = normal.y,
      normalZ = normal.z;
    // plane is used as if it is its normal; the first three components are assumed to be normalized
    var radEffective =
      Math.abs(
        normalX * halfAxes[Matrix3.COLUMN0ROW0] +
          normalY * halfAxes[Matrix3.COLUMN0ROW1] +
          normalZ * halfAxes[Matrix3.COLUMN0ROW2]
      ) +
      Math.abs(
        normalX * halfAxes[Matrix3.COLUMN1ROW0] +
          normalY * halfAxes[Matrix3.COLUMN1ROW1] +
          normalZ * halfAxes[Matrix3.COLUMN1ROW2]
      ) +
      Math.abs(
        normalX * halfAxes[Matrix3.COLUMN2ROW0] +
          normalY * halfAxes[Matrix3.COLUMN2ROW1] +
          normalZ * halfAxes[Matrix3.COLUMN2ROW2]
      );
    var distanceToPlane = Cartesian3.dot(normal, center) + plane.distance;

    if (distanceToPlane <= -radEffective) {
      // The entire box is on the negative side of the plane normal
      return Intersect$1.OUTSIDE;
    } else if (distanceToPlane >= radEffective) {
      // The entire box is on the positive side of the plane normal
      return Intersect$1.INSIDE;
    }
    return Intersect$1.INTERSECTING;
  };

  var scratchCartesianU = new Cartesian3();
  var scratchCartesianV = new Cartesian3();
  var scratchCartesianW = new Cartesian3();
  var scratchPPrime = new Cartesian3();

  /**
   * Computes the estimated distance squared from the closest point on a bounding box to a point.
   *
   * @param {OrientedBoundingBox} box The box.
   * @param {Cartesian3} cartesian The point
   * @returns {Number} The estimated distance squared from the bounding sphere to the point.
   *
   * @example
   * // Sort bounding boxes from back to front
   * boxes.sort(function(a, b) {
   *     return Cesium.OrientedBoundingBox.distanceSquaredTo(b, camera.positionWC) - Cesium.OrientedBoundingBox.distanceSquaredTo(a, camera.positionWC);
   * });
   */
  OrientedBoundingBox.distanceSquaredTo = function (box, cartesian) {
    // See Geometric Tools for Computer Graphics 10.4.2

    //>>includeStart('debug', pragmas.debug);
    if (!defined(box)) {
      throw new DeveloperError("box is required.");
    }
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    var offset = Cartesian3.subtract(cartesian, box.center, scratchOffset);

    var halfAxes = box.halfAxes;
    var u = Matrix3.getColumn(halfAxes, 0, scratchCartesianU);
    var v = Matrix3.getColumn(halfAxes, 1, scratchCartesianV);
    var w = Matrix3.getColumn(halfAxes, 2, scratchCartesianW);

    var uHalf = Cartesian3.magnitude(u);
    var vHalf = Cartesian3.magnitude(v);
    var wHalf = Cartesian3.magnitude(w);

    Cartesian3.normalize(u, u);
    Cartesian3.normalize(v, v);
    Cartesian3.normalize(w, w);

    var pPrime = scratchPPrime;
    pPrime.x = Cartesian3.dot(offset, u);
    pPrime.y = Cartesian3.dot(offset, v);
    pPrime.z = Cartesian3.dot(offset, w);

    var distanceSquared = 0.0;
    var d;

    if (pPrime.x < -uHalf) {
      d = pPrime.x + uHalf;
      distanceSquared += d * d;
    } else if (pPrime.x > uHalf) {
      d = pPrime.x - uHalf;
      distanceSquared += d * d;
    }

    if (pPrime.y < -vHalf) {
      d = pPrime.y + vHalf;
      distanceSquared += d * d;
    } else if (pPrime.y > vHalf) {
      d = pPrime.y - vHalf;
      distanceSquared += d * d;
    }

    if (pPrime.z < -wHalf) {
      d = pPrime.z + wHalf;
      distanceSquared += d * d;
    } else if (pPrime.z > wHalf) {
      d = pPrime.z - wHalf;
      distanceSquared += d * d;
    }

    return distanceSquared;
  };

  var scratchCorner = new Cartesian3();
  var scratchToCenter = new Cartesian3();

  /**
   * The distances calculated by the vector from the center of the bounding box to position projected onto direction.
   * <br>
   * If you imagine the infinite number of planes with normal direction, this computes the smallest distance to the
   * closest and farthest planes from position that intersect the bounding box.
   *
   * @param {OrientedBoundingBox} box The bounding box to calculate the distance to.
   * @param {Cartesian3} position The position to calculate the distance from.
   * @param {Cartesian3} direction The direction from position.
   * @param {Interval} [result] A Interval to store the nearest and farthest distances.
   * @returns {Interval} The nearest and farthest distances on the bounding box from position in direction.
   */
  OrientedBoundingBox.computePlaneDistances = function (
    box,
    position,
    direction,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(box)) {
      throw new DeveloperError("box is required.");
    }

    if (!defined(position)) {
      throw new DeveloperError("position is required.");
    }

    if (!defined(direction)) {
      throw new DeveloperError("direction is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Interval();
    }

    var minDist = Number.POSITIVE_INFINITY;
    var maxDist = Number.NEGATIVE_INFINITY;

    var center = box.center;
    var halfAxes = box.halfAxes;

    var u = Matrix3.getColumn(halfAxes, 0, scratchCartesianU);
    var v = Matrix3.getColumn(halfAxes, 1, scratchCartesianV);
    var w = Matrix3.getColumn(halfAxes, 2, scratchCartesianW);

    // project first corner
    var corner = Cartesian3.add(u, v, scratchCorner);
    Cartesian3.add(corner, w, corner);
    Cartesian3.add(corner, center, corner);

    var toCenter = Cartesian3.subtract(corner, position, scratchToCenter);
    var mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project second corner
    Cartesian3.add(center, u, corner);
    Cartesian3.add(corner, v, corner);
    Cartesian3.subtract(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project third corner
    Cartesian3.add(center, u, corner);
    Cartesian3.subtract(corner, v, corner);
    Cartesian3.add(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project fourth corner
    Cartesian3.add(center, u, corner);
    Cartesian3.subtract(corner, v, corner);
    Cartesian3.subtract(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project fifth corner
    Cartesian3.subtract(center, u, corner);
    Cartesian3.add(corner, v, corner);
    Cartesian3.add(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project sixth corner
    Cartesian3.subtract(center, u, corner);
    Cartesian3.add(corner, v, corner);
    Cartesian3.subtract(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project seventh corner
    Cartesian3.subtract(center, u, corner);
    Cartesian3.subtract(corner, v, corner);
    Cartesian3.add(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    // project eighth corner
    Cartesian3.subtract(center, u, corner);
    Cartesian3.subtract(corner, v, corner);
    Cartesian3.subtract(corner, w, corner);

    Cartesian3.subtract(corner, position, toCenter);
    mag = Cartesian3.dot(direction, toCenter);

    minDist = Math.min(mag, minDist);
    maxDist = Math.max(mag, maxDist);

    result.start = minDist;
    result.stop = maxDist;
    return result;
  };

  var scratchBoundingSphere$1 = new BoundingSphere();

  /**
   * Determines whether or not a bounding box is hidden from view by the occluder.
   *
   * @param {OrientedBoundingBox} box The bounding box surrounding the occludee object.
   * @param {Occluder} occluder The occluder.
   * @returns {Boolean} <code>true</code> if the box is not visible; otherwise <code>false</code>.
   */
  OrientedBoundingBox.isOccluded = function (box, occluder) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(box)) {
      throw new DeveloperError("box is required.");
    }
    if (!defined(occluder)) {
      throw new DeveloperError("occluder is required.");
    }
    //>>includeEnd('debug');

    var sphere = BoundingSphere.fromOrientedBoundingBox(
      box,
      scratchBoundingSphere$1
    );

    return !occluder.isBoundingSphereVisible(sphere);
  };

  /**
   * Determines which side of a plane the oriented bounding box is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
   *                      intersects the plane.
   */
  OrientedBoundingBox.prototype.intersectPlane = function (plane) {
    return OrientedBoundingBox.intersectPlane(this, plane);
  };

  /**
   * Computes the estimated distance squared from the closest point on a bounding box to a point.
   *
   * @param {Cartesian3} cartesian The point
   * @returns {Number} The estimated distance squared from the bounding sphere to the point.
   *
   * @example
   * // Sort bounding boxes from back to front
   * boxes.sort(function(a, b) {
   *     return b.distanceSquaredTo(camera.positionWC) - a.distanceSquaredTo(camera.positionWC);
   * });
   */
  OrientedBoundingBox.prototype.distanceSquaredTo = function (cartesian) {
    return OrientedBoundingBox.distanceSquaredTo(this, cartesian);
  };

  /**
   * The distances calculated by the vector from the center of the bounding box to position projected onto direction.
   * <br>
   * If you imagine the infinite number of planes with normal direction, this computes the smallest distance to the
   * closest and farthest planes from position that intersect the bounding box.
   *
   * @param {Cartesian3} position The position to calculate the distance from.
   * @param {Cartesian3} direction The direction from position.
   * @param {Interval} [result] A Interval to store the nearest and farthest distances.
   * @returns {Interval} The nearest and farthest distances on the bounding box from position in direction.
   */
  OrientedBoundingBox.prototype.computePlaneDistances = function (
    position,
    direction,
    result
  ) {
    return OrientedBoundingBox.computePlaneDistances(
      this,
      position,
      direction,
      result
    );
  };

  /**
   * Determines whether or not a bounding box is hidden from view by the occluder.
   *
   * @param {Occluder} occluder The occluder.
   * @returns {Boolean} <code>true</code> if the sphere is not visible; otherwise <code>false</code>.
   */
  OrientedBoundingBox.prototype.isOccluded = function (occluder) {
    return OrientedBoundingBox.isOccluded(this, occluder);
  };

  /**
   * Compares the provided OrientedBoundingBox componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {OrientedBoundingBox} left The first OrientedBoundingBox.
   * @param {OrientedBoundingBox} right The second OrientedBoundingBox.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  OrientedBoundingBox.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Cartesian3.equals(left.center, right.center) &&
        Matrix3.equals(left.halfAxes, right.halfAxes))
    );
  };

  /**
   * Duplicates this OrientedBoundingBox instance.
   *
   * @param {OrientedBoundingBox} [result] The object onto which to store the result.
   * @returns {OrientedBoundingBox} The modified result parameter or a new OrientedBoundingBox instance if one was not provided.
   */
  OrientedBoundingBox.prototype.clone = function (result) {
    return OrientedBoundingBox.clone(this, result);
  };

  /**
   * Compares this OrientedBoundingBox against the provided OrientedBoundingBox componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {OrientedBoundingBox} [right] The right hand side OrientedBoundingBox.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  OrientedBoundingBox.prototype.equals = function (right) {
    return OrientedBoundingBox.equals(this, right);
  };

  var RIGHT_SHIFT = 1.0 / 256.0;
  var LEFT_SHIFT = 256.0;

  /**
   * Attribute compression and decompression functions.
   *
   * @namespace AttributeCompression
   *
   * @private
   */
  var AttributeCompression = {};

  /**
   * Encodes a normalized vector into 2 SNORM values in the range of [0-rangeMax] following the 'oct' encoding.
   *
   * Oct encoding is a compact representation of unit length vectors.
   * The 'oct' encoding is described in "A Survey of Efficient Representations of Independent Unit Vectors",
   * Cigolle et al 2014: {@link http://jcgt.org/published/0003/02/01/}
   *
   * @param {Cartesian3} vector The normalized vector to be compressed into 2 component 'oct' encoding.
   * @param {Cartesian2} result The 2 component oct-encoded unit length vector.
   * @param {Number} rangeMax The maximum value of the SNORM range. The encoded vector is stored in log2(rangeMax+1) bits.
   * @returns {Cartesian2} The 2 component oct-encoded unit length vector.
   *
   * @exception {DeveloperError} vector must be normalized.
   *
   * @see AttributeCompression.octDecodeInRange
   */
  AttributeCompression.octEncodeInRange = function (vector, rangeMax, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("vector", vector);
    Check.defined("result", result);
    var magSquared = Cartesian3.magnitudeSquared(vector);
    if (Math.abs(magSquared - 1.0) > CesiumMath.EPSILON6) {
      throw new DeveloperError("vector must be normalized.");
    }
    //>>includeEnd('debug');

    result.x =
      vector.x / (Math.abs(vector.x) + Math.abs(vector.y) + Math.abs(vector.z));
    result.y =
      vector.y / (Math.abs(vector.x) + Math.abs(vector.y) + Math.abs(vector.z));
    if (vector.z < 0) {
      var x = result.x;
      var y = result.y;
      result.x = (1.0 - Math.abs(y)) * CesiumMath.signNotZero(x);
      result.y = (1.0 - Math.abs(x)) * CesiumMath.signNotZero(y);
    }

    result.x = CesiumMath.toSNorm(result.x, rangeMax);
    result.y = CesiumMath.toSNorm(result.y, rangeMax);

    return result;
  };

  /**
   * Encodes a normalized vector into 2 SNORM values in the range of [0-255] following the 'oct' encoding.
   *
   * @param {Cartesian3} vector The normalized vector to be compressed into 2 byte 'oct' encoding.
   * @param {Cartesian2} result The 2 byte oct-encoded unit length vector.
   * @returns {Cartesian2} The 2 byte oct-encoded unit length vector.
   *
   * @exception {DeveloperError} vector must be normalized.
   *
   * @see AttributeCompression.octEncodeInRange
   * @see AttributeCompression.octDecode
   */
  AttributeCompression.octEncode = function (vector, result) {
    return AttributeCompression.octEncodeInRange(vector, 255, result);
  };

  var octEncodeScratch = new Cartesian2();
  var uint8ForceArray = new Uint8Array(1);
  function forceUint8(value) {
    uint8ForceArray[0] = value;
    return uint8ForceArray[0];
  }
  /**
   * @param {Cartesian3} vector The normalized vector to be compressed into 4 byte 'oct' encoding.
   * @param {Cartesian4} result The 4 byte oct-encoded unit length vector.
   * @returns {Cartesian4} The 4 byte oct-encoded unit length vector.
   *
   * @exception {DeveloperError} vector must be normalized.
   *
   * @see AttributeCompression.octEncodeInRange
   * @see AttributeCompression.octDecodeFromCartesian4
   */
  AttributeCompression.octEncodeToCartesian4 = function (vector, result) {
    AttributeCompression.octEncodeInRange(vector, 65535, octEncodeScratch);
    result.x = forceUint8(octEncodeScratch.x * RIGHT_SHIFT);
    result.y = forceUint8(octEncodeScratch.x);
    result.z = forceUint8(octEncodeScratch.y * RIGHT_SHIFT);
    result.w = forceUint8(octEncodeScratch.y);
    return result;
  };

  /**
   * Decodes a unit-length vector in 'oct' encoding to a normalized 3-component vector.
   *
   * @param {Number} x The x component of the oct-encoded unit length vector.
   * @param {Number} y The y component of the oct-encoded unit length vector.
   * @param {Number} rangeMax The maximum value of the SNORM range. The encoded vector is stored in log2(rangeMax+1) bits.
   * @param {Cartesian3} result The decoded and normalized vector
   * @returns {Cartesian3} The decoded and normalized vector.
   *
   * @exception {DeveloperError} x and y must be unsigned normalized integers between 0 and rangeMax.
   *
   * @see AttributeCompression.octEncodeInRange
   */
  AttributeCompression.octDecodeInRange = function (x, y, rangeMax, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("result", result);
    if (x < 0 || x > rangeMax || y < 0 || y > rangeMax) {
      throw new DeveloperError(
        "x and y must be unsigned normalized integers between 0 and " + rangeMax
      );
    }
    //>>includeEnd('debug');

    result.x = CesiumMath.fromSNorm(x, rangeMax);
    result.y = CesiumMath.fromSNorm(y, rangeMax);
    result.z = 1.0 - (Math.abs(result.x) + Math.abs(result.y));

    if (result.z < 0.0) {
      var oldVX = result.x;
      result.x = (1.0 - Math.abs(result.y)) * CesiumMath.signNotZero(oldVX);
      result.y = (1.0 - Math.abs(oldVX)) * CesiumMath.signNotZero(result.y);
    }

    return Cartesian3.normalize(result, result);
  };

  /**
   * Decodes a unit-length vector in 2 byte 'oct' encoding to a normalized 3-component vector.
   *
   * @param {Number} x The x component of the oct-encoded unit length vector.
   * @param {Number} y The y component of the oct-encoded unit length vector.
   * @param {Cartesian3} result The decoded and normalized vector.
   * @returns {Cartesian3} The decoded and normalized vector.
   *
   * @exception {DeveloperError} x and y must be an unsigned normalized integer between 0 and 255.
   *
   * @see AttributeCompression.octDecodeInRange
   */
  AttributeCompression.octDecode = function (x, y, result) {
    return AttributeCompression.octDecodeInRange(x, y, 255, result);
  };

  /**
   * Decodes a unit-length vector in 4 byte 'oct' encoding to a normalized 3-component vector.
   *
   * @param {Cartesian4} encoded The oct-encoded unit length vector.
   * @param {Cartesian3} result The decoded and normalized vector.
   * @returns {Cartesian3} The decoded and normalized vector.
   *
   * @exception {DeveloperError} x, y, z, and w must be unsigned normalized integers between 0 and 255.
   *
   * @see AttributeCompression.octDecodeInRange
   * @see AttributeCompression.octEncodeToCartesian4
   */
  AttributeCompression.octDecodeFromCartesian4 = function (encoded, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("encoded", encoded);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');
    var x = encoded.x;
    var y = encoded.y;
    var z = encoded.z;
    var w = encoded.w;
    //>>includeStart('debug', pragmas.debug);
    if (
      x < 0 ||
      x > 255 ||
      y < 0 ||
      y > 255 ||
      z < 0 ||
      z > 255 ||
      w < 0 ||
      w > 255
    ) {
      throw new DeveloperError(
        "x, y, z, and w must be unsigned normalized integers between 0 and 255"
      );
    }
    //>>includeEnd('debug');

    var xOct16 = x * LEFT_SHIFT + y;
    var yOct16 = z * LEFT_SHIFT + w;
    return AttributeCompression.octDecodeInRange(xOct16, yOct16, 65535, result);
  };

  /**
   * Packs an oct encoded vector into a single floating-point number.
   *
   * @param {Cartesian2} encoded The oct encoded vector.
   * @returns {Number} The oct encoded vector packed into a single float.
   *
   */
  AttributeCompression.octPackFloat = function (encoded) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("encoded", encoded);
    //>>includeEnd('debug');
    return 256.0 * encoded.x + encoded.y;
  };

  var scratchEncodeCart2 = new Cartesian2();

  /**
   * Encodes a normalized vector into 2 SNORM values in the range of [0-255] following the 'oct' encoding and
   * stores those values in a single float-point number.
   *
   * @param {Cartesian3} vector The normalized vector to be compressed into 2 byte 'oct' encoding.
   * @returns {Number} The 2 byte oct-encoded unit length vector.
   *
   * @exception {DeveloperError} vector must be normalized.
   */
  AttributeCompression.octEncodeFloat = function (vector) {
    AttributeCompression.octEncode(vector, scratchEncodeCart2);
    return AttributeCompression.octPackFloat(scratchEncodeCart2);
  };

  /**
   * Decodes a unit-length vector in 'oct' encoding packed in a floating-point number to a normalized 3-component vector.
   *
   * @param {Number} value The oct-encoded unit length vector stored as a single floating-point number.
   * @param {Cartesian3} result The decoded and normalized vector
   * @returns {Cartesian3} The decoded and normalized vector.
   *
   */
  AttributeCompression.octDecodeFloat = function (value, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("value", value);
    //>>includeEnd('debug');

    var temp = value / 256.0;
    var x = Math.floor(temp);
    var y = (temp - x) * 256.0;

    return AttributeCompression.octDecode(x, y, result);
  };

  /**
   * Encodes three normalized vectors into 6 SNORM values in the range of [0-255] following the 'oct' encoding and
   * packs those into two floating-point numbers.
   *
   * @param {Cartesian3} v1 A normalized vector to be compressed.
   * @param {Cartesian3} v2 A normalized vector to be compressed.
   * @param {Cartesian3} v3 A normalized vector to be compressed.
   * @param {Cartesian2} result The 'oct' encoded vectors packed into two floating-point numbers.
   * @returns {Cartesian2} The 'oct' encoded vectors packed into two floating-point numbers.
   *
   */
  AttributeCompression.octPack = function (v1, v2, v3, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("v1", v1);
    Check.defined("v2", v2);
    Check.defined("v3", v3);
    Check.defined("result", result);
    //>>includeEnd('debug');

    var encoded1 = AttributeCompression.octEncodeFloat(v1);
    var encoded2 = AttributeCompression.octEncodeFloat(v2);

    var encoded3 = AttributeCompression.octEncode(v3, scratchEncodeCart2);
    result.x = 65536.0 * encoded3.x + encoded1;
    result.y = 65536.0 * encoded3.y + encoded2;
    return result;
  };

  /**
   * Decodes three unit-length vectors in 'oct' encoding packed into a floating-point number to a normalized 3-component vector.
   *
   * @param {Cartesian2} packed The three oct-encoded unit length vectors stored as two floating-point number.
   * @param {Cartesian3} v1 One decoded and normalized vector.
   * @param {Cartesian3} v2 One decoded and normalized vector.
   * @param {Cartesian3} v3 One decoded and normalized vector.
   */
  AttributeCompression.octUnpack = function (packed, v1, v2, v3) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("packed", packed);
    Check.defined("v1", v1);
    Check.defined("v2", v2);
    Check.defined("v3", v3);
    //>>includeEnd('debug');

    var temp = packed.x / 65536.0;
    var x = Math.floor(temp);
    var encodedFloat1 = (temp - x) * 65536.0;

    temp = packed.y / 65536.0;
    var y = Math.floor(temp);
    var encodedFloat2 = (temp - y) * 65536.0;

    AttributeCompression.octDecodeFloat(encodedFloat1, v1);
    AttributeCompression.octDecodeFloat(encodedFloat2, v2);
    AttributeCompression.octDecode(x, y, v3);
  };

  /**
   * Pack texture coordinates into a single float. The texture coordinates will only preserve 12 bits of precision.
   *
   * @param {Cartesian2} textureCoordinates The texture coordinates to compress.  Both coordinates must be in the range 0.0-1.0.
   * @returns {Number} The packed texture coordinates.
   *
   */
  AttributeCompression.compressTextureCoordinates = function (
    textureCoordinates
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("textureCoordinates", textureCoordinates);
    //>>includeEnd('debug');

    // Move x and y to the range 0-4095;
    var x = (textureCoordinates.x * 4095.0) | 0;
    var y = (textureCoordinates.y * 4095.0) | 0;
    return 4096.0 * x + y;
  };

  /**
   * Decompresses texture coordinates that were packed into a single float.
   *
   * @param {Number} compressed The compressed texture coordinates.
   * @param {Cartesian2} result The decompressed texture coordinates.
   * @returns {Cartesian2} The modified result parameter.
   *
   */
  AttributeCompression.decompressTextureCoordinates = function (
    compressed,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("compressed", compressed);
    Check.defined("result", result);
    //>>includeEnd('debug');

    var temp = compressed / 4096.0;
    var xZeroTo4095 = Math.floor(temp);
    result.x = xZeroTo4095 / 4095.0;
    result.y = (compressed - xZeroTo4095 * 4096) / 4095;
    return result;
  };

  function zigZagDecode(value) {
    return (value >> 1) ^ -(value & 1);
  }

  /**
   * Decodes delta and ZigZag encoded vertices. This modifies the buffers in place.
   *
   * @param {Uint16Array} uBuffer The buffer view of u values.
   * @param {Uint16Array} vBuffer The buffer view of v values.
   * @param {Uint16Array} [heightBuffer] The buffer view of height values.
   *
   * @see {@link https://github.com/CesiumGS/quantized-mesh|quantized-mesh-1.0 terrain format}
   */
  AttributeCompression.zigZagDeltaDecode = function (
    uBuffer,
    vBuffer,
    heightBuffer
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("uBuffer", uBuffer);
    Check.defined("vBuffer", vBuffer);
    Check.typeOf.number.equals(
      "uBuffer.length",
      "vBuffer.length",
      uBuffer.length,
      vBuffer.length
    );
    if (defined(heightBuffer)) {
      Check.typeOf.number.equals(
        "uBuffer.length",
        "heightBuffer.length",
        uBuffer.length,
        heightBuffer.length
      );
    }
    //>>includeEnd('debug');

    var count = uBuffer.length;

    var u = 0;
    var v = 0;
    var height = 0;

    for (var i = 0; i < count; ++i) {
      u += zigZagDecode(uBuffer[i]);
      v += zigZagDecode(vBuffer[i]);

      uBuffer[i] = u;
      vBuffer[i] = v;

      if (defined(heightBuffer)) {
        height += zigZagDecode(heightBuffer[i]);
        heightBuffer[i] = height;
      }
    }
  };

  /**
   * Enum containing WebGL Constant values by name.
   * for use without an active WebGL context, or in cases where certain constants are unavailable using the WebGL context
   * (For example, in [Safari 9]{@link https://github.com/CesiumGS/cesium/issues/2989}).
   *
   * These match the constants from the [WebGL 1.0]{@link https://www.khronos.org/registry/webgl/specs/latest/1.0/}
   * and [WebGL 2.0]{@link https://www.khronos.org/registry/webgl/specs/latest/2.0/}
   * specifications.
   *
   * @enum {Number}
   */
  var WebGLConstants = {
    DEPTH_BUFFER_BIT: 0x00000100,
    STENCIL_BUFFER_BIT: 0x00000400,
    COLOR_BUFFER_BIT: 0x00004000,
    POINTS: 0x0000,
    LINES: 0x0001,
    LINE_LOOP: 0x0002,
    LINE_STRIP: 0x0003,
    TRIANGLES: 0x0004,
    TRIANGLE_STRIP: 0x0005,
    TRIANGLE_FAN: 0x0006,
    ZERO: 0,
    ONE: 1,
    SRC_COLOR: 0x0300,
    ONE_MINUS_SRC_COLOR: 0x0301,
    SRC_ALPHA: 0x0302,
    ONE_MINUS_SRC_ALPHA: 0x0303,
    DST_ALPHA: 0x0304,
    ONE_MINUS_DST_ALPHA: 0x0305,
    DST_COLOR: 0x0306,
    ONE_MINUS_DST_COLOR: 0x0307,
    SRC_ALPHA_SATURATE: 0x0308,
    FUNC_ADD: 0x8006,
    BLEND_EQUATION: 0x8009,
    BLEND_EQUATION_RGB: 0x8009, // same as BLEND_EQUATION
    BLEND_EQUATION_ALPHA: 0x883d,
    FUNC_SUBTRACT: 0x800a,
    FUNC_REVERSE_SUBTRACT: 0x800b,
    BLEND_DST_RGB: 0x80c8,
    BLEND_SRC_RGB: 0x80c9,
    BLEND_DST_ALPHA: 0x80ca,
    BLEND_SRC_ALPHA: 0x80cb,
    CONSTANT_COLOR: 0x8001,
    ONE_MINUS_CONSTANT_COLOR: 0x8002,
    CONSTANT_ALPHA: 0x8003,
    ONE_MINUS_CONSTANT_ALPHA: 0x8004,
    BLEND_COLOR: 0x8005,
    ARRAY_BUFFER: 0x8892,
    ELEMENT_ARRAY_BUFFER: 0x8893,
    ARRAY_BUFFER_BINDING: 0x8894,
    ELEMENT_ARRAY_BUFFER_BINDING: 0x8895,
    STREAM_DRAW: 0x88e0,
    STATIC_DRAW: 0x88e4,
    DYNAMIC_DRAW: 0x88e8,
    BUFFER_SIZE: 0x8764,
    BUFFER_USAGE: 0x8765,
    CURRENT_VERTEX_ATTRIB: 0x8626,
    FRONT: 0x0404,
    BACK: 0x0405,
    FRONT_AND_BACK: 0x0408,
    CULL_FACE: 0x0b44,
    BLEND: 0x0be2,
    DITHER: 0x0bd0,
    STENCIL_TEST: 0x0b90,
    DEPTH_TEST: 0x0b71,
    SCISSOR_TEST: 0x0c11,
    POLYGON_OFFSET_FILL: 0x8037,
    SAMPLE_ALPHA_TO_COVERAGE: 0x809e,
    SAMPLE_COVERAGE: 0x80a0,
    NO_ERROR: 0,
    INVALID_ENUM: 0x0500,
    INVALID_VALUE: 0x0501,
    INVALID_OPERATION: 0x0502,
    OUT_OF_MEMORY: 0x0505,
    CW: 0x0900,
    CCW: 0x0901,
    LINE_WIDTH: 0x0b21,
    ALIASED_POINT_SIZE_RANGE: 0x846d,
    ALIASED_LINE_WIDTH_RANGE: 0x846e,
    CULL_FACE_MODE: 0x0b45,
    FRONT_FACE: 0x0b46,
    DEPTH_RANGE: 0x0b70,
    DEPTH_WRITEMASK: 0x0b72,
    DEPTH_CLEAR_VALUE: 0x0b73,
    DEPTH_FUNC: 0x0b74,
    STENCIL_CLEAR_VALUE: 0x0b91,
    STENCIL_FUNC: 0x0b92,
    STENCIL_FAIL: 0x0b94,
    STENCIL_PASS_DEPTH_FAIL: 0x0b95,
    STENCIL_PASS_DEPTH_PASS: 0x0b96,
    STENCIL_REF: 0x0b97,
    STENCIL_VALUE_MASK: 0x0b93,
    STENCIL_WRITEMASK: 0x0b98,
    STENCIL_BACK_FUNC: 0x8800,
    STENCIL_BACK_FAIL: 0x8801,
    STENCIL_BACK_PASS_DEPTH_FAIL: 0x8802,
    STENCIL_BACK_PASS_DEPTH_PASS: 0x8803,
    STENCIL_BACK_REF: 0x8ca3,
    STENCIL_BACK_VALUE_MASK: 0x8ca4,
    STENCIL_BACK_WRITEMASK: 0x8ca5,
    VIEWPORT: 0x0ba2,
    SCISSOR_BOX: 0x0c10,
    COLOR_CLEAR_VALUE: 0x0c22,
    COLOR_WRITEMASK: 0x0c23,
    UNPACK_ALIGNMENT: 0x0cf5,
    PACK_ALIGNMENT: 0x0d05,
    MAX_TEXTURE_SIZE: 0x0d33,
    MAX_VIEWPORT_DIMS: 0x0d3a,
    SUBPIXEL_BITS: 0x0d50,
    RED_BITS: 0x0d52,
    GREEN_BITS: 0x0d53,
    BLUE_BITS: 0x0d54,
    ALPHA_BITS: 0x0d55,
    DEPTH_BITS: 0x0d56,
    STENCIL_BITS: 0x0d57,
    POLYGON_OFFSET_UNITS: 0x2a00,
    POLYGON_OFFSET_FACTOR: 0x8038,
    TEXTURE_BINDING_2D: 0x8069,
    SAMPLE_BUFFERS: 0x80a8,
    SAMPLES: 0x80a9,
    SAMPLE_COVERAGE_VALUE: 0x80aa,
    SAMPLE_COVERAGE_INVERT: 0x80ab,
    COMPRESSED_TEXTURE_FORMATS: 0x86a3,
    DONT_CARE: 0x1100,
    FASTEST: 0x1101,
    NICEST: 0x1102,
    GENERATE_MIPMAP_HINT: 0x8192,
    BYTE: 0x1400,
    UNSIGNED_BYTE: 0x1401,
    SHORT: 0x1402,
    UNSIGNED_SHORT: 0x1403,
    INT: 0x1404,
    UNSIGNED_INT: 0x1405,
    FLOAT: 0x1406,
    DEPTH_COMPONENT: 0x1902,
    ALPHA: 0x1906,
    RGB: 0x1907,
    RGBA: 0x1908,
    LUMINANCE: 0x1909,
    LUMINANCE_ALPHA: 0x190a,
    UNSIGNED_SHORT_4_4_4_4: 0x8033,
    UNSIGNED_SHORT_5_5_5_1: 0x8034,
    UNSIGNED_SHORT_5_6_5: 0x8363,
    FRAGMENT_SHADER: 0x8b30,
    VERTEX_SHADER: 0x8b31,
    MAX_VERTEX_ATTRIBS: 0x8869,
    MAX_VERTEX_UNIFORM_VECTORS: 0x8dfb,
    MAX_VARYING_VECTORS: 0x8dfc,
    MAX_COMBINED_TEXTURE_IMAGE_UNITS: 0x8b4d,
    MAX_VERTEX_TEXTURE_IMAGE_UNITS: 0x8b4c,
    MAX_TEXTURE_IMAGE_UNITS: 0x8872,
    MAX_FRAGMENT_UNIFORM_VECTORS: 0x8dfd,
    SHADER_TYPE: 0x8b4f,
    DELETE_STATUS: 0x8b80,
    LINK_STATUS: 0x8b82,
    VALIDATE_STATUS: 0x8b83,
    ATTACHED_SHADERS: 0x8b85,
    ACTIVE_UNIFORMS: 0x8b86,
    ACTIVE_ATTRIBUTES: 0x8b89,
    SHADING_LANGUAGE_VERSION: 0x8b8c,
    CURRENT_PROGRAM: 0x8b8d,
    NEVER: 0x0200,
    LESS: 0x0201,
    EQUAL: 0x0202,
    LEQUAL: 0x0203,
    GREATER: 0x0204,
    NOTEQUAL: 0x0205,
    GEQUAL: 0x0206,
    ALWAYS: 0x0207,
    KEEP: 0x1e00,
    REPLACE: 0x1e01,
    INCR: 0x1e02,
    DECR: 0x1e03,
    INVERT: 0x150a,
    INCR_WRAP: 0x8507,
    DECR_WRAP: 0x8508,
    VENDOR: 0x1f00,
    RENDERER: 0x1f01,
    VERSION: 0x1f02,
    NEAREST: 0x2600,
    LINEAR: 0x2601,
    NEAREST_MIPMAP_NEAREST: 0x2700,
    LINEAR_MIPMAP_NEAREST: 0x2701,
    NEAREST_MIPMAP_LINEAR: 0x2702,
    LINEAR_MIPMAP_LINEAR: 0x2703,
    TEXTURE_MAG_FILTER: 0x2800,
    TEXTURE_MIN_FILTER: 0x2801,
    TEXTURE_WRAP_S: 0x2802,
    TEXTURE_WRAP_T: 0x2803,
    TEXTURE_2D: 0x0de1,
    TEXTURE: 0x1702,
    TEXTURE_CUBE_MAP: 0x8513,
    TEXTURE_BINDING_CUBE_MAP: 0x8514,
    TEXTURE_CUBE_MAP_POSITIVE_X: 0x8515,
    TEXTURE_CUBE_MAP_NEGATIVE_X: 0x8516,
    TEXTURE_CUBE_MAP_POSITIVE_Y: 0x8517,
    TEXTURE_CUBE_MAP_NEGATIVE_Y: 0x8518,
    TEXTURE_CUBE_MAP_POSITIVE_Z: 0x8519,
    TEXTURE_CUBE_MAP_NEGATIVE_Z: 0x851a,
    MAX_CUBE_MAP_TEXTURE_SIZE: 0x851c,
    TEXTURE0: 0x84c0,
    TEXTURE1: 0x84c1,
    TEXTURE2: 0x84c2,
    TEXTURE3: 0x84c3,
    TEXTURE4: 0x84c4,
    TEXTURE5: 0x84c5,
    TEXTURE6: 0x84c6,
    TEXTURE7: 0x84c7,
    TEXTURE8: 0x84c8,
    TEXTURE9: 0x84c9,
    TEXTURE10: 0x84ca,
    TEXTURE11: 0x84cb,
    TEXTURE12: 0x84cc,
    TEXTURE13: 0x84cd,
    TEXTURE14: 0x84ce,
    TEXTURE15: 0x84cf,
    TEXTURE16: 0x84d0,
    TEXTURE17: 0x84d1,
    TEXTURE18: 0x84d2,
    TEXTURE19: 0x84d3,
    TEXTURE20: 0x84d4,
    TEXTURE21: 0x84d5,
    TEXTURE22: 0x84d6,
    TEXTURE23: 0x84d7,
    TEXTURE24: 0x84d8,
    TEXTURE25: 0x84d9,
    TEXTURE26: 0x84da,
    TEXTURE27: 0x84db,
    TEXTURE28: 0x84dc,
    TEXTURE29: 0x84dd,
    TEXTURE30: 0x84de,
    TEXTURE31: 0x84df,
    ACTIVE_TEXTURE: 0x84e0,
    REPEAT: 0x2901,
    CLAMP_TO_EDGE: 0x812f,
    MIRRORED_REPEAT: 0x8370,
    FLOAT_VEC2: 0x8b50,
    FLOAT_VEC3: 0x8b51,
    FLOAT_VEC4: 0x8b52,
    INT_VEC2: 0x8b53,
    INT_VEC3: 0x8b54,
    INT_VEC4: 0x8b55,
    BOOL: 0x8b56,
    BOOL_VEC2: 0x8b57,
    BOOL_VEC3: 0x8b58,
    BOOL_VEC4: 0x8b59,
    FLOAT_MAT2: 0x8b5a,
    FLOAT_MAT3: 0x8b5b,
    FLOAT_MAT4: 0x8b5c,
    SAMPLER_2D: 0x8b5e,
    SAMPLER_CUBE: 0x8b60,
    VERTEX_ATTRIB_ARRAY_ENABLED: 0x8622,
    VERTEX_ATTRIB_ARRAY_SIZE: 0x8623,
    VERTEX_ATTRIB_ARRAY_STRIDE: 0x8624,
    VERTEX_ATTRIB_ARRAY_TYPE: 0x8625,
    VERTEX_ATTRIB_ARRAY_NORMALIZED: 0x886a,
    VERTEX_ATTRIB_ARRAY_POINTER: 0x8645,
    VERTEX_ATTRIB_ARRAY_BUFFER_BINDING: 0x889f,
    IMPLEMENTATION_COLOR_READ_TYPE: 0x8b9a,
    IMPLEMENTATION_COLOR_READ_FORMAT: 0x8b9b,
    COMPILE_STATUS: 0x8b81,
    LOW_FLOAT: 0x8df0,
    MEDIUM_FLOAT: 0x8df1,
    HIGH_FLOAT: 0x8df2,
    LOW_INT: 0x8df3,
    MEDIUM_INT: 0x8df4,
    HIGH_INT: 0x8df5,
    FRAMEBUFFER: 0x8d40,
    RENDERBUFFER: 0x8d41,
    RGBA4: 0x8056,
    RGB5_A1: 0x8057,
    RGB565: 0x8d62,
    DEPTH_COMPONENT16: 0x81a5,
    STENCIL_INDEX: 0x1901,
    STENCIL_INDEX8: 0x8d48,
    DEPTH_STENCIL: 0x84f9,
    RENDERBUFFER_WIDTH: 0x8d42,
    RENDERBUFFER_HEIGHT: 0x8d43,
    RENDERBUFFER_INTERNAL_FORMAT: 0x8d44,
    RENDERBUFFER_RED_SIZE: 0x8d50,
    RENDERBUFFER_GREEN_SIZE: 0x8d51,
    RENDERBUFFER_BLUE_SIZE: 0x8d52,
    RENDERBUFFER_ALPHA_SIZE: 0x8d53,
    RENDERBUFFER_DEPTH_SIZE: 0x8d54,
    RENDERBUFFER_STENCIL_SIZE: 0x8d55,
    FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE: 0x8cd0,
    FRAMEBUFFER_ATTACHMENT_OBJECT_NAME: 0x8cd1,
    FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL: 0x8cd2,
    FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE: 0x8cd3,
    COLOR_ATTACHMENT0: 0x8ce0,
    DEPTH_ATTACHMENT: 0x8d00,
    STENCIL_ATTACHMENT: 0x8d20,
    DEPTH_STENCIL_ATTACHMENT: 0x821a,
    NONE: 0,
    FRAMEBUFFER_COMPLETE: 0x8cd5,
    FRAMEBUFFER_INCOMPLETE_ATTACHMENT: 0x8cd6,
    FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: 0x8cd7,
    FRAMEBUFFER_INCOMPLETE_DIMENSIONS: 0x8cd9,
    FRAMEBUFFER_UNSUPPORTED: 0x8cdd,
    FRAMEBUFFER_BINDING: 0x8ca6,
    RENDERBUFFER_BINDING: 0x8ca7,
    MAX_RENDERBUFFER_SIZE: 0x84e8,
    INVALID_FRAMEBUFFER_OPERATION: 0x0506,
    UNPACK_FLIP_Y_WEBGL: 0x9240,
    UNPACK_PREMULTIPLY_ALPHA_WEBGL: 0x9241,
    CONTEXT_LOST_WEBGL: 0x9242,
    UNPACK_COLORSPACE_CONVERSION_WEBGL: 0x9243,
    BROWSER_DEFAULT_WEBGL: 0x9244,

    // WEBGL_compressed_texture_s3tc
    COMPRESSED_RGB_S3TC_DXT1_EXT: 0x83f0,
    COMPRESSED_RGBA_S3TC_DXT1_EXT: 0x83f1,
    COMPRESSED_RGBA_S3TC_DXT3_EXT: 0x83f2,
    COMPRESSED_RGBA_S3TC_DXT5_EXT: 0x83f3,

    // WEBGL_compressed_texture_pvrtc
    COMPRESSED_RGB_PVRTC_4BPPV1_IMG: 0x8c00,
    COMPRESSED_RGB_PVRTC_2BPPV1_IMG: 0x8c01,
    COMPRESSED_RGBA_PVRTC_4BPPV1_IMG: 0x8c02,
    COMPRESSED_RGBA_PVRTC_2BPPV1_IMG: 0x8c03,

    // WEBGL_compressed_texture_etc1
    COMPRESSED_RGB_ETC1_WEBGL: 0x8d64,

    // EXT_color_buffer_half_float
    HALF_FLOAT_OES: 0x8d61,

    // Desktop OpenGL
    DOUBLE: 0x140a,

    // WebGL 2
    READ_BUFFER: 0x0c02,
    UNPACK_ROW_LENGTH: 0x0cf2,
    UNPACK_SKIP_ROWS: 0x0cf3,
    UNPACK_SKIP_PIXELS: 0x0cf4,
    PACK_ROW_LENGTH: 0x0d02,
    PACK_SKIP_ROWS: 0x0d03,
    PACK_SKIP_PIXELS: 0x0d04,
    COLOR: 0x1800,
    DEPTH: 0x1801,
    STENCIL: 0x1802,
    RED: 0x1903,
    RGB8: 0x8051,
    RGBA8: 0x8058,
    RGB10_A2: 0x8059,
    TEXTURE_BINDING_3D: 0x806a,
    UNPACK_SKIP_IMAGES: 0x806d,
    UNPACK_IMAGE_HEIGHT: 0x806e,
    TEXTURE_3D: 0x806f,
    TEXTURE_WRAP_R: 0x8072,
    MAX_3D_TEXTURE_SIZE: 0x8073,
    UNSIGNED_INT_2_10_10_10_REV: 0x8368,
    MAX_ELEMENTS_VERTICES: 0x80e8,
    MAX_ELEMENTS_INDICES: 0x80e9,
    TEXTURE_MIN_LOD: 0x813a,
    TEXTURE_MAX_LOD: 0x813b,
    TEXTURE_BASE_LEVEL: 0x813c,
    TEXTURE_MAX_LEVEL: 0x813d,
    MIN: 0x8007,
    MAX: 0x8008,
    DEPTH_COMPONENT24: 0x81a6,
    MAX_TEXTURE_LOD_BIAS: 0x84fd,
    TEXTURE_COMPARE_MODE: 0x884c,
    TEXTURE_COMPARE_FUNC: 0x884d,
    CURRENT_QUERY: 0x8865,
    QUERY_RESULT: 0x8866,
    QUERY_RESULT_AVAILABLE: 0x8867,
    STREAM_READ: 0x88e1,
    STREAM_COPY: 0x88e2,
    STATIC_READ: 0x88e5,
    STATIC_COPY: 0x88e6,
    DYNAMIC_READ: 0x88e9,
    DYNAMIC_COPY: 0x88ea,
    MAX_DRAW_BUFFERS: 0x8824,
    DRAW_BUFFER0: 0x8825,
    DRAW_BUFFER1: 0x8826,
    DRAW_BUFFER2: 0x8827,
    DRAW_BUFFER3: 0x8828,
    DRAW_BUFFER4: 0x8829,
    DRAW_BUFFER5: 0x882a,
    DRAW_BUFFER6: 0x882b,
    DRAW_BUFFER7: 0x882c,
    DRAW_BUFFER8: 0x882d,
    DRAW_BUFFER9: 0x882e,
    DRAW_BUFFER10: 0x882f,
    DRAW_BUFFER11: 0x8830,
    DRAW_BUFFER12: 0x8831,
    DRAW_BUFFER13: 0x8832,
    DRAW_BUFFER14: 0x8833,
    DRAW_BUFFER15: 0x8834,
    MAX_FRAGMENT_UNIFORM_COMPONENTS: 0x8b49,
    MAX_VERTEX_UNIFORM_COMPONENTS: 0x8b4a,
    SAMPLER_3D: 0x8b5f,
    SAMPLER_2D_SHADOW: 0x8b62,
    FRAGMENT_SHADER_DERIVATIVE_HINT: 0x8b8b,
    PIXEL_PACK_BUFFER: 0x88eb,
    PIXEL_UNPACK_BUFFER: 0x88ec,
    PIXEL_PACK_BUFFER_BINDING: 0x88ed,
    PIXEL_UNPACK_BUFFER_BINDING: 0x88ef,
    FLOAT_MAT2x3: 0x8b65,
    FLOAT_MAT2x4: 0x8b66,
    FLOAT_MAT3x2: 0x8b67,
    FLOAT_MAT3x4: 0x8b68,
    FLOAT_MAT4x2: 0x8b69,
    FLOAT_MAT4x3: 0x8b6a,
    SRGB: 0x8c40,
    SRGB8: 0x8c41,
    SRGB8_ALPHA8: 0x8c43,
    COMPARE_REF_TO_TEXTURE: 0x884e,
    RGBA32F: 0x8814,
    RGB32F: 0x8815,
    RGBA16F: 0x881a,
    RGB16F: 0x881b,
    VERTEX_ATTRIB_ARRAY_INTEGER: 0x88fd,
    MAX_ARRAY_TEXTURE_LAYERS: 0x88ff,
    MIN_PROGRAM_TEXEL_OFFSET: 0x8904,
    MAX_PROGRAM_TEXEL_OFFSET: 0x8905,
    MAX_VARYING_COMPONENTS: 0x8b4b,
    TEXTURE_2D_ARRAY: 0x8c1a,
    TEXTURE_BINDING_2D_ARRAY: 0x8c1d,
    R11F_G11F_B10F: 0x8c3a,
    UNSIGNED_INT_10F_11F_11F_REV: 0x8c3b,
    RGB9_E5: 0x8c3d,
    UNSIGNED_INT_5_9_9_9_REV: 0x8c3e,
    TRANSFORM_FEEDBACK_BUFFER_MODE: 0x8c7f,
    MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS: 0x8c80,
    TRANSFORM_FEEDBACK_VARYINGS: 0x8c83,
    TRANSFORM_FEEDBACK_BUFFER_START: 0x8c84,
    TRANSFORM_FEEDBACK_BUFFER_SIZE: 0x8c85,
    TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN: 0x8c88,
    RASTERIZER_DISCARD: 0x8c89,
    MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS: 0x8c8a,
    MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS: 0x8c8b,
    INTERLEAVED_ATTRIBS: 0x8c8c,
    SEPARATE_ATTRIBS: 0x8c8d,
    TRANSFORM_FEEDBACK_BUFFER: 0x8c8e,
    TRANSFORM_FEEDBACK_BUFFER_BINDING: 0x8c8f,
    RGBA32UI: 0x8d70,
    RGB32UI: 0x8d71,
    RGBA16UI: 0x8d76,
    RGB16UI: 0x8d77,
    RGBA8UI: 0x8d7c,
    RGB8UI: 0x8d7d,
    RGBA32I: 0x8d82,
    RGB32I: 0x8d83,
    RGBA16I: 0x8d88,
    RGB16I: 0x8d89,
    RGBA8I: 0x8d8e,
    RGB8I: 0x8d8f,
    RED_INTEGER: 0x8d94,
    RGB_INTEGER: 0x8d98,
    RGBA_INTEGER: 0x8d99,
    SAMPLER_2D_ARRAY: 0x8dc1,
    SAMPLER_2D_ARRAY_SHADOW: 0x8dc4,
    SAMPLER_CUBE_SHADOW: 0x8dc5,
    UNSIGNED_INT_VEC2: 0x8dc6,
    UNSIGNED_INT_VEC3: 0x8dc7,
    UNSIGNED_INT_VEC4: 0x8dc8,
    INT_SAMPLER_2D: 0x8dca,
    INT_SAMPLER_3D: 0x8dcb,
    INT_SAMPLER_CUBE: 0x8dcc,
    INT_SAMPLER_2D_ARRAY: 0x8dcf,
    UNSIGNED_INT_SAMPLER_2D: 0x8dd2,
    UNSIGNED_INT_SAMPLER_3D: 0x8dd3,
    UNSIGNED_INT_SAMPLER_CUBE: 0x8dd4,
    UNSIGNED_INT_SAMPLER_2D_ARRAY: 0x8dd7,
    DEPTH_COMPONENT32F: 0x8cac,
    DEPTH32F_STENCIL8: 0x8cad,
    FLOAT_32_UNSIGNED_INT_24_8_REV: 0x8dad,
    FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING: 0x8210,
    FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE: 0x8211,
    FRAMEBUFFER_ATTACHMENT_RED_SIZE: 0x8212,
    FRAMEBUFFER_ATTACHMENT_GREEN_SIZE: 0x8213,
    FRAMEBUFFER_ATTACHMENT_BLUE_SIZE: 0x8214,
    FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE: 0x8215,
    FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE: 0x8216,
    FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE: 0x8217,
    FRAMEBUFFER_DEFAULT: 0x8218,
    UNSIGNED_INT_24_8: 0x84fa,
    DEPTH24_STENCIL8: 0x88f0,
    UNSIGNED_NORMALIZED: 0x8c17,
    DRAW_FRAMEBUFFER_BINDING: 0x8ca6, // Same as FRAMEBUFFER_BINDING
    READ_FRAMEBUFFER: 0x8ca8,
    DRAW_FRAMEBUFFER: 0x8ca9,
    READ_FRAMEBUFFER_BINDING: 0x8caa,
    RENDERBUFFER_SAMPLES: 0x8cab,
    FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER: 0x8cd4,
    MAX_COLOR_ATTACHMENTS: 0x8cdf,
    COLOR_ATTACHMENT1: 0x8ce1,
    COLOR_ATTACHMENT2: 0x8ce2,
    COLOR_ATTACHMENT3: 0x8ce3,
    COLOR_ATTACHMENT4: 0x8ce4,
    COLOR_ATTACHMENT5: 0x8ce5,
    COLOR_ATTACHMENT6: 0x8ce6,
    COLOR_ATTACHMENT7: 0x8ce7,
    COLOR_ATTACHMENT8: 0x8ce8,
    COLOR_ATTACHMENT9: 0x8ce9,
    COLOR_ATTACHMENT10: 0x8cea,
    COLOR_ATTACHMENT11: 0x8ceb,
    COLOR_ATTACHMENT12: 0x8cec,
    COLOR_ATTACHMENT13: 0x8ced,
    COLOR_ATTACHMENT14: 0x8cee,
    COLOR_ATTACHMENT15: 0x8cef,
    FRAMEBUFFER_INCOMPLETE_MULTISAMPLE: 0x8d56,
    MAX_SAMPLES: 0x8d57,
    HALF_FLOAT: 0x140b,
    RG: 0x8227,
    RG_INTEGER: 0x8228,
    R8: 0x8229,
    RG8: 0x822b,
    R16F: 0x822d,
    R32F: 0x822e,
    RG16F: 0x822f,
    RG32F: 0x8230,
    R8I: 0x8231,
    R8UI: 0x8232,
    R16I: 0x8233,
    R16UI: 0x8234,
    R32I: 0x8235,
    R32UI: 0x8236,
    RG8I: 0x8237,
    RG8UI: 0x8238,
    RG16I: 0x8239,
    RG16UI: 0x823a,
    RG32I: 0x823b,
    RG32UI: 0x823c,
    VERTEX_ARRAY_BINDING: 0x85b5,
    R8_SNORM: 0x8f94,
    RG8_SNORM: 0x8f95,
    RGB8_SNORM: 0x8f96,
    RGBA8_SNORM: 0x8f97,
    SIGNED_NORMALIZED: 0x8f9c,
    COPY_READ_BUFFER: 0x8f36,
    COPY_WRITE_BUFFER: 0x8f37,
    COPY_READ_BUFFER_BINDING: 0x8f36, // Same as COPY_READ_BUFFER
    COPY_WRITE_BUFFER_BINDING: 0x8f37, // Same as COPY_WRITE_BUFFER
    UNIFORM_BUFFER: 0x8a11,
    UNIFORM_BUFFER_BINDING: 0x8a28,
    UNIFORM_BUFFER_START: 0x8a29,
    UNIFORM_BUFFER_SIZE: 0x8a2a,
    MAX_VERTEX_UNIFORM_BLOCKS: 0x8a2b,
    MAX_FRAGMENT_UNIFORM_BLOCKS: 0x8a2d,
    MAX_COMBINED_UNIFORM_BLOCKS: 0x8a2e,
    MAX_UNIFORM_BUFFER_BINDINGS: 0x8a2f,
    MAX_UNIFORM_BLOCK_SIZE: 0x8a30,
    MAX_COMBINED_VERTEX_UNIFORM_COMPONENTS: 0x8a31,
    MAX_COMBINED_FRAGMENT_UNIFORM_COMPONENTS: 0x8a33,
    UNIFORM_BUFFER_OFFSET_ALIGNMENT: 0x8a34,
    ACTIVE_UNIFORM_BLOCKS: 0x8a36,
    UNIFORM_TYPE: 0x8a37,
    UNIFORM_SIZE: 0x8a38,
    UNIFORM_BLOCK_INDEX: 0x8a3a,
    UNIFORM_OFFSET: 0x8a3b,
    UNIFORM_ARRAY_STRIDE: 0x8a3c,
    UNIFORM_MATRIX_STRIDE: 0x8a3d,
    UNIFORM_IS_ROW_MAJOR: 0x8a3e,
    UNIFORM_BLOCK_BINDING: 0x8a3f,
    UNIFORM_BLOCK_DATA_SIZE: 0x8a40,
    UNIFORM_BLOCK_ACTIVE_UNIFORMS: 0x8a42,
    UNIFORM_BLOCK_ACTIVE_UNIFORM_INDICES: 0x8a43,
    UNIFORM_BLOCK_REFERENCED_BY_VERTEX_SHADER: 0x8a44,
    UNIFORM_BLOCK_REFERENCED_BY_FRAGMENT_SHADER: 0x8a46,
    INVALID_INDEX: 0xffffffff,
    MAX_VERTEX_OUTPUT_COMPONENTS: 0x9122,
    MAX_FRAGMENT_INPUT_COMPONENTS: 0x9125,
    MAX_SERVER_WAIT_TIMEOUT: 0x9111,
    OBJECT_TYPE: 0x9112,
    SYNC_CONDITION: 0x9113,
    SYNC_STATUS: 0x9114,
    SYNC_FLAGS: 0x9115,
    SYNC_FENCE: 0x9116,
    SYNC_GPU_COMMANDS_COMPLETE: 0x9117,
    UNSIGNALED: 0x9118,
    SIGNALED: 0x9119,
    ALREADY_SIGNALED: 0x911a,
    TIMEOUT_EXPIRED: 0x911b,
    CONDITION_SATISFIED: 0x911c,
    WAIT_FAILED: 0x911d,
    SYNC_FLUSH_COMMANDS_BIT: 0x00000001,
    VERTEX_ATTRIB_ARRAY_DIVISOR: 0x88fe,
    ANY_SAMPLES_PASSED: 0x8c2f,
    ANY_SAMPLES_PASSED_CONSERVATIVE: 0x8d6a,
    SAMPLER_BINDING: 0x8919,
    RGB10_A2UI: 0x906f,
    INT_2_10_10_10_REV: 0x8d9f,
    TRANSFORM_FEEDBACK: 0x8e22,
    TRANSFORM_FEEDBACK_PAUSED: 0x8e23,
    TRANSFORM_FEEDBACK_ACTIVE: 0x8e24,
    TRANSFORM_FEEDBACK_BINDING: 0x8e25,
    COMPRESSED_R11_EAC: 0x9270,
    COMPRESSED_SIGNED_R11_EAC: 0x9271,
    COMPRESSED_RG11_EAC: 0x9272,
    COMPRESSED_SIGNED_RG11_EAC: 0x9273,
    COMPRESSED_RGB8_ETC2: 0x9274,
    COMPRESSED_SRGB8_ETC2: 0x9275,
    COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2: 0x9276,
    COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2: 0x9277,
    COMPRESSED_RGBA8_ETC2_EAC: 0x9278,
    COMPRESSED_SRGB8_ALPHA8_ETC2_EAC: 0x9279,
    TEXTURE_IMMUTABLE_FORMAT: 0x912f,
    MAX_ELEMENT_INDEX: 0x8d6b,
    TEXTURE_IMMUTABLE_LEVELS: 0x82df,

    // Extensions
    MAX_TEXTURE_MAX_ANISOTROPY_EXT: 0x84ff,
  };
  var WebGLConstants$1 = Object.freeze(WebGLConstants);

  /**
   * WebGL component datatypes.  Components are intrinsics,
   * which form attributes, which form vertices.
   *
   * @enum {Number}
   */
  var ComponentDatatype = {
    /**
     * 8-bit signed byte corresponding to <code>gl.BYTE</code> and the type
     * of an element in <code>Int8Array</code>.
     *
     * @type {Number}
     * @constant
     */
    BYTE: WebGLConstants$1.BYTE,

    /**
     * 8-bit unsigned byte corresponding to <code>UNSIGNED_BYTE</code> and the type
     * of an element in <code>Uint8Array</code>.
     *
     * @type {Number}
     * @constant
     */
    UNSIGNED_BYTE: WebGLConstants$1.UNSIGNED_BYTE,

    /**
     * 16-bit signed short corresponding to <code>SHORT</code> and the type
     * of an element in <code>Int16Array</code>.
     *
     * @type {Number}
     * @constant
     */
    SHORT: WebGLConstants$1.SHORT,

    /**
     * 16-bit unsigned short corresponding to <code>UNSIGNED_SHORT</code> and the type
     * of an element in <code>Uint16Array</code>.
     *
     * @type {Number}
     * @constant
     */
    UNSIGNED_SHORT: WebGLConstants$1.UNSIGNED_SHORT,

    /**
     * 32-bit signed int corresponding to <code>INT</code> and the type
     * of an element in <code>Int32Array</code>.
     *
     * @memberOf ComponentDatatype
     *
     * @type {Number}
     * @constant
     */
    INT: WebGLConstants$1.INT,

    /**
     * 32-bit unsigned int corresponding to <code>UNSIGNED_INT</code> and the type
     * of an element in <code>Uint32Array</code>.
     *
     * @memberOf ComponentDatatype
     *
     * @type {Number}
     * @constant
     */
    UNSIGNED_INT: WebGLConstants$1.UNSIGNED_INT,

    /**
     * 32-bit floating-point corresponding to <code>FLOAT</code> and the type
     * of an element in <code>Float32Array</code>.
     *
     * @type {Number}
     * @constant
     */
    FLOAT: WebGLConstants$1.FLOAT,

    /**
     * 64-bit floating-point corresponding to <code>gl.DOUBLE</code> (in Desktop OpenGL;
     * this is not supported in WebGL, and is emulated in Cesium via {@link GeometryPipeline.encodeAttribute})
     * and the type of an element in <code>Float64Array</code>.
     *
     * @memberOf ComponentDatatype
     *
     * @type {Number}
     * @constant
     * @default 0x140A
     */
    DOUBLE: WebGLConstants$1.DOUBLE,
  };

  /**
   * Returns the size, in bytes, of the corresponding datatype.
   *
   * @param {ComponentDatatype} componentDatatype The component datatype to get the size of.
   * @returns {Number} The size in bytes.
   *
   * @exception {DeveloperError} componentDatatype is not a valid value.
   *
   * @example
   * // Returns Int8Array.BYTES_PER_ELEMENT
   * var size = Cesium.ComponentDatatype.getSizeInBytes(Cesium.ComponentDatatype.BYTE);
   */
  ComponentDatatype.getSizeInBytes = function (componentDatatype) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(componentDatatype)) {
      throw new DeveloperError("value is required.");
    }
    //>>includeEnd('debug');

    switch (componentDatatype) {
      case ComponentDatatype.BYTE:
        return Int8Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.UNSIGNED_BYTE:
        return Uint8Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.SHORT:
        return Int16Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.UNSIGNED_SHORT:
        return Uint16Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.INT:
        return Int32Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.UNSIGNED_INT:
        return Uint32Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.FLOAT:
        return Float32Array.BYTES_PER_ELEMENT;
      case ComponentDatatype.DOUBLE:
        return Float64Array.BYTES_PER_ELEMENT;
      //>>includeStart('debug', pragmas.debug);
      default:
        throw new DeveloperError("componentDatatype is not a valid value.");
      //>>includeEnd('debug');
    }
  };

  /**
   * Gets the {@link ComponentDatatype} for the provided TypedArray instance.
   *
   * @param {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} array The typed array.
   * @returns {ComponentDatatype} The ComponentDatatype for the provided array, or undefined if the array is not a TypedArray.
   */
  ComponentDatatype.fromTypedArray = function (array) {
    if (array instanceof Int8Array) {
      return ComponentDatatype.BYTE;
    }
    if (array instanceof Uint8Array) {
      return ComponentDatatype.UNSIGNED_BYTE;
    }
    if (array instanceof Int16Array) {
      return ComponentDatatype.SHORT;
    }
    if (array instanceof Uint16Array) {
      return ComponentDatatype.UNSIGNED_SHORT;
    }
    if (array instanceof Int32Array) {
      return ComponentDatatype.INT;
    }
    if (array instanceof Uint32Array) {
      return ComponentDatatype.UNSIGNED_INT;
    }
    if (array instanceof Float32Array) {
      return ComponentDatatype.FLOAT;
    }
    if (array instanceof Float64Array) {
      return ComponentDatatype.DOUBLE;
    }
  };

  /**
   * Validates that the provided component datatype is a valid {@link ComponentDatatype}
   *
   * @param {ComponentDatatype} componentDatatype The component datatype to validate.
   * @returns {Boolean} <code>true</code> if the provided component datatype is a valid value; otherwise, <code>false</code>.
   *
   * @example
   * if (!Cesium.ComponentDatatype.validate(componentDatatype)) {
   *   throw new Cesium.DeveloperError('componentDatatype must be a valid value.');
   * }
   */
  ComponentDatatype.validate = function (componentDatatype) {
    return (
      defined(componentDatatype) &&
      (componentDatatype === ComponentDatatype.BYTE ||
        componentDatatype === ComponentDatatype.UNSIGNED_BYTE ||
        componentDatatype === ComponentDatatype.SHORT ||
        componentDatatype === ComponentDatatype.UNSIGNED_SHORT ||
        componentDatatype === ComponentDatatype.INT ||
        componentDatatype === ComponentDatatype.UNSIGNED_INT ||
        componentDatatype === ComponentDatatype.FLOAT ||
        componentDatatype === ComponentDatatype.DOUBLE)
    );
  };

  /**
   * Creates a typed array corresponding to component data type.
   *
   * @param {ComponentDatatype} componentDatatype The component data type.
   * @param {Number|Array} valuesOrLength The length of the array to create or an array.
   * @returns {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} A typed array.
   *
   * @exception {DeveloperError} componentDatatype is not a valid value.
   *
   * @example
   * // creates a Float32Array with length of 100
   * var typedArray = Cesium.ComponentDatatype.createTypedArray(Cesium.ComponentDatatype.FLOAT, 100);
   */
  ComponentDatatype.createTypedArray = function (
    componentDatatype,
    valuesOrLength
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(componentDatatype)) {
      throw new DeveloperError("componentDatatype is required.");
    }
    if (!defined(valuesOrLength)) {
      throw new DeveloperError("valuesOrLength is required.");
    }
    //>>includeEnd('debug');

    switch (componentDatatype) {
      case ComponentDatatype.BYTE:
        return new Int8Array(valuesOrLength);
      case ComponentDatatype.UNSIGNED_BYTE:
        return new Uint8Array(valuesOrLength);
      case ComponentDatatype.SHORT:
        return new Int16Array(valuesOrLength);
      case ComponentDatatype.UNSIGNED_SHORT:
        return new Uint16Array(valuesOrLength);
      case ComponentDatatype.INT:
        return new Int32Array(valuesOrLength);
      case ComponentDatatype.UNSIGNED_INT:
        return new Uint32Array(valuesOrLength);
      case ComponentDatatype.FLOAT:
        return new Float32Array(valuesOrLength);
      case ComponentDatatype.DOUBLE:
        return new Float64Array(valuesOrLength);
      //>>includeStart('debug', pragmas.debug);
      default:
        throw new DeveloperError("componentDatatype is not a valid value.");
      //>>includeEnd('debug');
    }
  };

  /**
   * Creates a typed view of an array of bytes.
   *
   * @param {ComponentDatatype} componentDatatype The type of the view to create.
   * @param {ArrayBuffer} buffer The buffer storage to use for the view.
   * @param {Number} [byteOffset] The offset, in bytes, to the first element in the view.
   * @param {Number} [length] The number of elements in the view.
   * @returns {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} A typed array view of the buffer.
   *
   * @exception {DeveloperError} componentDatatype is not a valid value.
   */
  ComponentDatatype.createArrayBufferView = function (
    componentDatatype,
    buffer,
    byteOffset,
    length
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(componentDatatype)) {
      throw new DeveloperError("componentDatatype is required.");
    }
    if (!defined(buffer)) {
      throw new DeveloperError("buffer is required.");
    }
    //>>includeEnd('debug');

    byteOffset = defaultValue(byteOffset, 0);
    length = defaultValue(
      length,
      (buffer.byteLength - byteOffset) /
        ComponentDatatype.getSizeInBytes(componentDatatype)
    );

    switch (componentDatatype) {
      case ComponentDatatype.BYTE:
        return new Int8Array(buffer, byteOffset, length);
      case ComponentDatatype.UNSIGNED_BYTE:
        return new Uint8Array(buffer, byteOffset, length);
      case ComponentDatatype.SHORT:
        return new Int16Array(buffer, byteOffset, length);
      case ComponentDatatype.UNSIGNED_SHORT:
        return new Uint16Array(buffer, byteOffset, length);
      case ComponentDatatype.INT:
        return new Int32Array(buffer, byteOffset, length);
      case ComponentDatatype.UNSIGNED_INT:
        return new Uint32Array(buffer, byteOffset, length);
      case ComponentDatatype.FLOAT:
        return new Float32Array(buffer, byteOffset, length);
      case ComponentDatatype.DOUBLE:
        return new Float64Array(buffer, byteOffset, length);
      //>>includeStart('debug', pragmas.debug);
      default:
        throw new DeveloperError("componentDatatype is not a valid value.");
      //>>includeEnd('debug');
    }
  };

  /**
   * Get the ComponentDatatype from its name.
   *
   * @param {String} name The name of the ComponentDatatype.
   * @returns {ComponentDatatype} The ComponentDatatype.
   *
   * @exception {DeveloperError} name is not a valid value.
   */
  ComponentDatatype.fromName = function (name) {
    switch (name) {
      case "BYTE":
        return ComponentDatatype.BYTE;
      case "UNSIGNED_BYTE":
        return ComponentDatatype.UNSIGNED_BYTE;
      case "SHORT":
        return ComponentDatatype.SHORT;
      case "UNSIGNED_SHORT":
        return ComponentDatatype.UNSIGNED_SHORT;
      case "INT":
        return ComponentDatatype.INT;
      case "UNSIGNED_INT":
        return ComponentDatatype.UNSIGNED_INT;
      case "FLOAT":
        return ComponentDatatype.FLOAT;
      case "DOUBLE":
        return ComponentDatatype.DOUBLE;
      //>>includeStart('debug', pragmas.debug);
      default:
        throw new DeveloperError("name is not a valid value.");
      //>>includeEnd('debug');
    }
  };
  var ComponentDatatype$1 = Object.freeze(ComponentDatatype);

  /**
   * This enumerated type is used to determine how the vertices of the terrain mesh are compressed.
   *
   * @enum {Number}
   *
   * @private
   */
  var TerrainQuantization = {
    /**
     * The vertices are not compressed.
     *
     * @type {Number}
     * @constant
     */
    NONE: 0,

    /**
     * The vertices are compressed to 12 bits.
     *
     * @type {Number}
     * @constant
     */
    BITS12: 1,
  };
  var TerrainQuantization$1 = Object.freeze(TerrainQuantization);

  var cartesian3Scratch = new Cartesian3();
  var cartesian3DimScratch = new Cartesian3();
  var cartesian2Scratch = new Cartesian2();
  var matrix4Scratch = new Matrix4();
  var matrix4Scratch2 = new Matrix4();

  var SHIFT_LEFT_12 = Math.pow(2.0, 12.0);

  /**
   * Data used to quantize and pack the terrain mesh. The position can be unpacked for picking and all attributes
   * are unpacked in the vertex shader.
   *
   * @alias TerrainEncoding
   * @constructor
   *
   * @param {AxisAlignedBoundingBox} axisAlignedBoundingBox The bounds of the tile in the east-north-up coordinates at the tiles center.
   * @param {Number} minimumHeight The minimum height.
   * @param {Number} maximumHeight The maximum height.
   * @param {Matrix4} fromENU The east-north-up to fixed frame matrix at the center of the terrain mesh.
   * @param {Boolean} hasVertexNormals If the mesh has vertex normals.
   * @param {Boolean} [hasWebMercatorT=false] true if the terrain data includes a Web Mercator texture coordinate; otherwise, false.
   *
   * @private
   */
  function TerrainEncoding(
    axisAlignedBoundingBox,
    minimumHeight,
    maximumHeight,
    fromENU,
    hasVertexNormals,
    hasWebMercatorT
  ) {
    var quantization = TerrainQuantization$1.NONE;
    var center;
    var toENU;
    var matrix;

    if (
      defined(axisAlignedBoundingBox) &&
      defined(minimumHeight) &&
      defined(maximumHeight) &&
      defined(fromENU)
    ) {
      var minimum = axisAlignedBoundingBox.minimum;
      var maximum = axisAlignedBoundingBox.maximum;

      var dimensions = Cartesian3.subtract(
        maximum,
        minimum,
        cartesian3DimScratch
      );
      var hDim = maximumHeight - minimumHeight;
      var maxDim = Math.max(Cartesian3.maximumComponent(dimensions), hDim);

      if (maxDim < SHIFT_LEFT_12 - 1.0) {
        quantization = TerrainQuantization$1.BITS12;
      } else {
        quantization = TerrainQuantization$1.NONE;
      }

      center = axisAlignedBoundingBox.center;
      toENU = Matrix4.inverseTransformation(fromENU, new Matrix4());

      var translation = Cartesian3.negate(minimum, cartesian3Scratch);
      Matrix4.multiply(
        Matrix4.fromTranslation(translation, matrix4Scratch),
        toENU,
        toENU
      );

      var scale = cartesian3Scratch;
      scale.x = 1.0 / dimensions.x;
      scale.y = 1.0 / dimensions.y;
      scale.z = 1.0 / dimensions.z;
      Matrix4.multiply(Matrix4.fromScale(scale, matrix4Scratch), toENU, toENU);

      matrix = Matrix4.clone(fromENU);
      Matrix4.setTranslation(matrix, Cartesian3.ZERO, matrix);

      fromENU = Matrix4.clone(fromENU, new Matrix4());

      var translationMatrix = Matrix4.fromTranslation(minimum, matrix4Scratch);
      var scaleMatrix = Matrix4.fromScale(dimensions, matrix4Scratch2);
      var st = Matrix4.multiply(translationMatrix, scaleMatrix, matrix4Scratch);

      Matrix4.multiply(fromENU, st, fromENU);
      Matrix4.multiply(matrix, st, matrix);
    }

    /**
     * How the vertices of the mesh were compressed.
     * @type {TerrainQuantization}
     */
    this.quantization = quantization;

    /**
     * The minimum height of the tile including the skirts.
     * @type {Number}
     */
    this.minimumHeight = minimumHeight;

    /**
     * The maximum height of the tile.
     * @type {Number}
     */
    this.maximumHeight = maximumHeight;

    /**
     * The center of the tile.
     * @type {Cartesian3}
     */
    this.center = center;

    /**
     * A matrix that takes a vertex from the tile, transforms it to east-north-up at the center and scales
     * it so each component is in the [0, 1] range.
     * @type {Matrix4}
     */
    this.toScaledENU = toENU;

    /**
     * A matrix that restores a vertex transformed with toScaledENU back to the earth fixed reference frame
     * @type {Matrix4}
     */
    this.fromScaledENU = fromENU;

    /**
     * The matrix used to decompress the terrain vertices in the shader for RTE rendering.
     * @type {Matrix4}
     */
    this.matrix = matrix;

    /**
     * The terrain mesh contains normals.
     * @type {Boolean}
     */
    this.hasVertexNormals = hasVertexNormals;

    /**
     * The terrain mesh contains a vertical texture coordinate following the Web Mercator projection.
     * @type {Boolean}
     */
    this.hasWebMercatorT = defaultValue(hasWebMercatorT, false);
  }

  TerrainEncoding.prototype.encode = function (
    vertexBuffer,
    bufferIndex,
    position,
    uv,
    height,
    normalToPack,
    webMercatorT
  ) {
    var u = uv.x;
    var v = uv.y;

    if (this.quantization === TerrainQuantization$1.BITS12) {
      position = Matrix4.multiplyByPoint(
        this.toScaledENU,
        position,
        cartesian3Scratch
      );

      position.x = CesiumMath.clamp(position.x, 0.0, 1.0);
      position.y = CesiumMath.clamp(position.y, 0.0, 1.0);
      position.z = CesiumMath.clamp(position.z, 0.0, 1.0);

      var hDim = this.maximumHeight - this.minimumHeight;
      var h = CesiumMath.clamp((height - this.minimumHeight) / hDim, 0.0, 1.0);

      Cartesian2.fromElements(position.x, position.y, cartesian2Scratch);
      var compressed0 = AttributeCompression.compressTextureCoordinates(
        cartesian2Scratch
      );

      Cartesian2.fromElements(position.z, h, cartesian2Scratch);
      var compressed1 = AttributeCompression.compressTextureCoordinates(
        cartesian2Scratch
      );

      Cartesian2.fromElements(u, v, cartesian2Scratch);
      var compressed2 = AttributeCompression.compressTextureCoordinates(
        cartesian2Scratch
      );

      vertexBuffer[bufferIndex++] = compressed0;
      vertexBuffer[bufferIndex++] = compressed1;
      vertexBuffer[bufferIndex++] = compressed2;

      if (this.hasWebMercatorT) {
        Cartesian2.fromElements(webMercatorT, 0.0, cartesian2Scratch);
        var compressed3 = AttributeCompression.compressTextureCoordinates(
          cartesian2Scratch
        );
        vertexBuffer[bufferIndex++] = compressed3;
      }
    } else {
      Cartesian3.subtract(position, this.center, cartesian3Scratch);

      vertexBuffer[bufferIndex++] = cartesian3Scratch.x;
      vertexBuffer[bufferIndex++] = cartesian3Scratch.y;
      vertexBuffer[bufferIndex++] = cartesian3Scratch.z;
      vertexBuffer[bufferIndex++] = height;
      vertexBuffer[bufferIndex++] = u;
      vertexBuffer[bufferIndex++] = v;

      if (this.hasWebMercatorT) {
        vertexBuffer[bufferIndex++] = webMercatorT;
      }
    }

    if (this.hasVertexNormals) {
      vertexBuffer[bufferIndex++] = AttributeCompression.octPackFloat(
        normalToPack
      );
    }

    return bufferIndex;
  };

  TerrainEncoding.prototype.decodePosition = function (buffer, index, result) {
    if (!defined(result)) {
      result = new Cartesian3();
    }

    index *= this.getStride();

    if (this.quantization === TerrainQuantization$1.BITS12) {
      var xy = AttributeCompression.decompressTextureCoordinates(
        buffer[index],
        cartesian2Scratch
      );
      result.x = xy.x;
      result.y = xy.y;

      var zh = AttributeCompression.decompressTextureCoordinates(
        buffer[index + 1],
        cartesian2Scratch
      );
      result.z = zh.x;

      return Matrix4.multiplyByPoint(this.fromScaledENU, result, result);
    }

    result.x = buffer[index];
    result.y = buffer[index + 1];
    result.z = buffer[index + 2];
    return Cartesian3.add(result, this.center, result);
  };

  TerrainEncoding.prototype.decodeTextureCoordinates = function (
    buffer,
    index,
    result
  ) {
    if (!defined(result)) {
      result = new Cartesian2();
    }

    index *= this.getStride();

    if (this.quantization === TerrainQuantization$1.BITS12) {
      return AttributeCompression.decompressTextureCoordinates(
        buffer[index + 2],
        result
      );
    }

    return Cartesian2.fromElements(buffer[index + 4], buffer[index + 5], result);
  };

  TerrainEncoding.prototype.decodeHeight = function (buffer, index) {
    index *= this.getStride();

    if (this.quantization === TerrainQuantization$1.BITS12) {
      var zh = AttributeCompression.decompressTextureCoordinates(
        buffer[index + 1],
        cartesian2Scratch
      );
      return (
        zh.y * (this.maximumHeight - this.minimumHeight) + this.minimumHeight
      );
    }

    return buffer[index + 3];
  };

  TerrainEncoding.prototype.decodeWebMercatorT = function (buffer, index) {
    index *= this.getStride();

    if (this.quantization === TerrainQuantization$1.BITS12) {
      return AttributeCompression.decompressTextureCoordinates(
        buffer[index + 3],
        cartesian2Scratch
      ).x;
    }

    return buffer[index + 6];
  };

  TerrainEncoding.prototype.getOctEncodedNormal = function (
    buffer,
    index,
    result
  ) {
    var stride = this.getStride();
    index = (index + 1) * stride - 1;

    var temp = buffer[index] / 256.0;
    var x = Math.floor(temp);
    var y = (temp - x) * 256.0;

    return Cartesian2.fromElements(x, y, result);
  };

  TerrainEncoding.prototype.getStride = function () {
    var vertexStride;

    switch (this.quantization) {
      case TerrainQuantization$1.BITS12:
        vertexStride = 3;
        break;
      default:
        vertexStride = 6;
    }

    if (this.hasWebMercatorT) {
      ++vertexStride;
    }

    if (this.hasVertexNormals) {
      ++vertexStride;
    }

    return vertexStride;
  };

  var attributesNone = {
    position3DAndHeight: 0,
    textureCoordAndEncodedNormals: 1,
  };
  var attributes = {
    compressed0: 0,
    compressed1: 1,
  };

  TerrainEncoding.prototype.getAttributes = function (buffer) {
    var datatype = ComponentDatatype$1.FLOAT;
    var sizeInBytes = ComponentDatatype$1.getSizeInBytes(datatype);
    var stride;

    if (this.quantization === TerrainQuantization$1.NONE) {
      var position3DAndHeightLength = 4;
      var numTexCoordComponents = 2;

      if (this.hasWebMercatorT) {
        ++numTexCoordComponents;
      }

      if (this.hasVertexNormals) {
        ++numTexCoordComponents;
      }

      stride = (position3DAndHeightLength + numTexCoordComponents) * sizeInBytes;

      return [
        {
          index: attributesNone.position3DAndHeight,
          vertexBuffer: buffer,
          componentDatatype: datatype,
          componentsPerAttribute: position3DAndHeightLength,
          offsetInBytes: 0,
          strideInBytes: stride,
        },
        {
          index: attributesNone.textureCoordAndEncodedNormals,
          vertexBuffer: buffer,
          componentDatatype: datatype,
          componentsPerAttribute: numTexCoordComponents,
          offsetInBytes: position3DAndHeightLength * sizeInBytes,
          strideInBytes: stride,
        },
      ];
    }

    var numCompressed0 = 3;
    var numCompressed1 = 0;

    if (this.hasWebMercatorT || this.hasVertexNormals) {
      ++numCompressed0;
    }

    if (this.hasWebMercatorT && this.hasVertexNormals) {
      ++numCompressed1;

      stride = (numCompressed0 + numCompressed1) * sizeInBytes;

      return [
        {
          index: attributes.compressed0,
          vertexBuffer: buffer,
          componentDatatype: datatype,
          componentsPerAttribute: numCompressed0,
          offsetInBytes: 0,
          strideInBytes: stride,
        },
        {
          index: attributes.compressed1,
          vertexBuffer: buffer,
          componentDatatype: datatype,
          componentsPerAttribute: numCompressed1,
          offsetInBytes: numCompressed0 * sizeInBytes,
          strideInBytes: stride,
        },
      ];
    }
    return [
      {
        index: attributes.compressed0,
        vertexBuffer: buffer,
        componentDatatype: datatype,
        componentsPerAttribute: numCompressed0,
      },
    ];
  };

  TerrainEncoding.prototype.getAttributeLocations = function () {
    if (this.quantization === TerrainQuantization$1.NONE) {
      return attributesNone;
    }
    return attributes;
  };

  TerrainEncoding.clone = function (encoding, result) {
    if (!defined(result)) {
      result = new TerrainEncoding();
    }

    result.quantization = encoding.quantization;
    result.minimumHeight = encoding.minimumHeight;
    result.maximumHeight = encoding.maximumHeight;
    result.center = Cartesian3.clone(encoding.center);
    result.toScaledENU = Matrix4.clone(encoding.toScaledENU);
    result.fromScaledENU = Matrix4.clone(encoding.fromScaledENU);
    result.matrix = Matrix4.clone(encoding.matrix);
    result.hasVertexNormals = encoding.hasVertexNormals;
    result.hasWebMercatorT = encoding.hasWebMercatorT;
    return result;
  };

  /**
   * The map projection used by Google Maps, Bing Maps, and most of ArcGIS Online, EPSG:3857.  This
   * projection use longitude and latitude expressed with the WGS84 and transforms them to Mercator using
   * the spherical (rather than ellipsoidal) equations.
   *
   * @alias WebMercatorProjection
   * @constructor
   *
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid.
   *
   * @see GeographicProjection
   */
  function WebMercatorProjection(ellipsoid) {
    this._ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    this._semimajorAxis = this._ellipsoid.maximumRadius;
    this._oneOverSemimajorAxis = 1.0 / this._semimajorAxis;
  }

  Object.defineProperties(WebMercatorProjection.prototype, {
    /**
     * Gets the {@link Ellipsoid}.
     *
     * @memberof WebMercatorProjection.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
  });

  /**
   * Converts a Mercator angle, in the range -PI to PI, to a geodetic latitude
   * in the range -PI/2 to PI/2.
   *
   * @param {Number} mercatorAngle The angle to convert.
   * @returns {Number} The geodetic latitude in radians.
   */
  WebMercatorProjection.mercatorAngleToGeodeticLatitude = function (
    mercatorAngle
  ) {
    return CesiumMath.PI_OVER_TWO - 2.0 * Math.atan(Math.exp(-mercatorAngle));
  };

  /**
   * Converts a geodetic latitude in radians, in the range -PI/2 to PI/2, to a Mercator
   * angle in the range -PI to PI.
   *
   * @param {Number} latitude The geodetic latitude in radians.
   * @returns {Number} The Mercator angle.
   */
  WebMercatorProjection.geodeticLatitudeToMercatorAngle = function (latitude) {
    // Clamp the latitude coordinate to the valid Mercator bounds.
    if (latitude > WebMercatorProjection.MaximumLatitude) {
      latitude = WebMercatorProjection.MaximumLatitude;
    } else if (latitude < -WebMercatorProjection.MaximumLatitude) {
      latitude = -WebMercatorProjection.MaximumLatitude;
    }
    var sinLatitude = Math.sin(latitude);
    return 0.5 * Math.log((1.0 + sinLatitude) / (1.0 - sinLatitude));
  };

  /**
   * The maximum latitude (both North and South) supported by a Web Mercator
   * (EPSG:3857) projection.  Technically, the Mercator projection is defined
   * for any latitude up to (but not including) 90 degrees, but it makes sense
   * to cut it off sooner because it grows exponentially with increasing latitude.
   * The logic behind this particular cutoff value, which is the one used by
   * Google Maps, Bing Maps, and Esri, is that it makes the projection
   * square.  That is, the rectangle is equal in the X and Y directions.
   *
   * The constant value is computed by calling:
   *    WebMercatorProjection.mercatorAngleToGeodeticLatitude(Math.PI)
   *
   * @type {Number}
   */
  WebMercatorProjection.MaximumLatitude = WebMercatorProjection.mercatorAngleToGeodeticLatitude(
    Math.PI
  );

  /**
   * Converts geodetic ellipsoid coordinates, in radians, to the equivalent Web Mercator
   * X, Y, Z coordinates expressed in meters and returned in a {@link Cartesian3}.  The height
   * is copied unmodified to the Z coordinate.
   *
   * @param {Cartographic} cartographic The cartographic coordinates in radians.
   * @param {Cartesian3} [result] The instance to which to copy the result, or undefined if a
   *        new instance should be created.
   * @returns {Cartesian3} The equivalent web mercator X, Y, Z coordinates, in meters.
   */
  WebMercatorProjection.prototype.project = function (cartographic, result) {
    var semimajorAxis = this._semimajorAxis;
    var x = cartographic.longitude * semimajorAxis;
    var y =
      WebMercatorProjection.geodeticLatitudeToMercatorAngle(
        cartographic.latitude
      ) * semimajorAxis;
    var z = cartographic.height;

    if (!defined(result)) {
      return new Cartesian3(x, y, z);
    }

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Converts Web Mercator X, Y coordinates, expressed in meters, to a {@link Cartographic}
   * containing geodetic ellipsoid coordinates.  The Z coordinate is copied unmodified to the
   * height.
   *
   * @param {Cartesian3} cartesian The web mercator Cartesian position to unrproject with height (z) in meters.
   * @param {Cartographic} [result] The instance to which to copy the result, or undefined if a
   *        new instance should be created.
   * @returns {Cartographic} The equivalent cartographic coordinates.
   */
  WebMercatorProjection.prototype.unproject = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required");
    }
    //>>includeEnd('debug');

    var oneOverEarthSemimajorAxis = this._oneOverSemimajorAxis;
    var longitude = cartesian.x * oneOverEarthSemimajorAxis;
    var latitude = WebMercatorProjection.mercatorAngleToGeodeticLatitude(
      cartesian.y * oneOverEarthSemimajorAxis
    );
    var height = cartesian.z;

    if (!defined(result)) {
      return new Cartographic(longitude, latitude, height);
    }

    result.longitude = longitude;
    result.latitude = latitude;
    result.height = height;
    return result;
  };

  /**
   * Contains functions to create a mesh from a heightmap image.
   *
   * @namespace HeightmapTessellator
   *
   * @private
   */
  var HeightmapTessellator = {};

  /**
   * The default structure of a heightmap, as given to {@link HeightmapTessellator.computeVertices}.
   *
   * @constant
   */
  HeightmapTessellator.DEFAULT_STRUCTURE = Object.freeze({
    heightScale: 1.0,
    heightOffset: 0.0,
    elementsPerHeight: 1,
    stride: 1,
    elementMultiplier: 256.0,
    isBigEndian: false,
  });

  var cartesian3Scratch$1 = new Cartesian3();
  var matrix4Scratch$1 = new Matrix4();
  var minimumScratch = new Cartesian3();
  var maximumScratch = new Cartesian3();

  /**
   * Fills an array of vertices from a heightmap image.
   *
   * @param {Object} options Object with the following properties:
   * @param {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} options.heightmap The heightmap to tessellate.
   * @param {Number} options.width The width of the heightmap, in height samples.
   * @param {Number} options.height The height of the heightmap, in height samples.
   * @param {Number} options.skirtHeight The height of skirts to drape at the edges of the heightmap.
   * @param {Rectangle} options.nativeRectangle A rectangle in the native coordinates of the heightmap's projection.  For
   *                 a heightmap with a geographic projection, this is degrees.  For the web mercator
   *                 projection, this is meters.
   * @param {Number} [options.exaggeration=1.0] The scale used to exaggerate the terrain.
   * @param {Rectangle} [options.rectangle] The rectangle covered by the heightmap, in geodetic coordinates with north, south, east and
   *                 west properties in radians.  Either rectangle or nativeRectangle must be provided.  If both
   *                 are provided, they're assumed to be consistent.
   * @param {Boolean} [options.isGeographic=true] True if the heightmap uses a {@link GeographicProjection}, or false if it uses
   *                  a {@link WebMercatorProjection}.
   * @param {Cartesian3} [options.relativeToCenter=Cartesian3.ZERO] The positions will be computed as <code>Cartesian3.subtract(worldPosition, relativeToCenter)</code>.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to which the heightmap applies.
   * @param {Object} [options.structure] An object describing the structure of the height data.
   * @param {Number} [options.structure.heightScale=1.0] The factor by which to multiply height samples in order to obtain
   *                 the height above the heightOffset, in meters.  The heightOffset is added to the resulting
   *                 height after multiplying by the scale.
   * @param {Number} [options.structure.heightOffset=0.0] The offset to add to the scaled height to obtain the final
   *                 height in meters.  The offset is added after the height sample is multiplied by the
   *                 heightScale.
   * @param {Number} [options.structure.elementsPerHeight=1] The number of elements in the buffer that make up a single height
   *                 sample.  This is usually 1, indicating that each element is a separate height sample.  If
   *                 it is greater than 1, that number of elements together form the height sample, which is
   *                 computed according to the structure.elementMultiplier and structure.isBigEndian properties.
   * @param {Number} [options.structure.stride=1] The number of elements to skip to get from the first element of
   *                 one height to the first element of the next height.
   * @param {Number} [options.structure.elementMultiplier=256.0] The multiplier used to compute the height value when the
   *                 stride property is greater than 1.  For example, if the stride is 4 and the strideMultiplier
   *                 is 256, the height is computed as follows:
   *                 `height = buffer[index] + buffer[index + 1] * 256 + buffer[index + 2] * 256 * 256 + buffer[index + 3] * 256 * 256 * 256`
   *                 This is assuming that the isBigEndian property is false.  If it is true, the order of the
   *                 elements is reversed.
   * @param {Number} [options.structure.lowestEncodedHeight] The lowest value that can be stored in the height buffer.  Any heights that are lower
   *                 than this value after encoding with the `heightScale` and `heightOffset` are clamped to this value.  For example, if the height
   *                 buffer is a `Uint16Array`, this value should be 0 because a `Uint16Array` cannot store negative numbers.  If this parameter is
   *                 not specified, no minimum value is enforced.
   * @param {Number} [options.structure.highestEncodedHeight] The highest value that can be stored in the height buffer.  Any heights that are higher
   *                 than this value after encoding with the `heightScale` and `heightOffset` are clamped to this value.  For example, if the height
   *                 buffer is a `Uint16Array`, this value should be `256 * 256 - 1` or 65535 because a `Uint16Array` cannot store numbers larger
   *                 than 65535.  If this parameter is not specified, no maximum value is enforced.
   * @param {Boolean} [options.structure.isBigEndian=false] Indicates endianness of the elements in the buffer when the
   *                  stride property is greater than 1.  If this property is false, the first element is the
   *                  low-order element.  If it is true, the first element is the high-order element.
   *
   * @example
   * var width = 5;
   * var height = 5;
   * var statistics = Cesium.HeightmapTessellator.computeVertices({
   *     heightmap : [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0],
   *     width : width,
   *     height : height,
   *     skirtHeight : 0.0,
   *     nativeRectangle : {
   *         west : 10.0,
   *         east : 20.0,
   *         south : 30.0,
   *         north : 40.0
   *     }
   * });
   *
   * var encoding = statistics.encoding;
   * var position = encoding.decodePosition(statistics.vertices, index * encoding.getStride());
   */
  HeightmapTessellator.computeVertices = function (options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.heightmap)) {
      throw new DeveloperError("options.heightmap is required.");
    }
    if (!defined(options.width) || !defined(options.height)) {
      throw new DeveloperError("options.width and options.height are required.");
    }
    if (!defined(options.nativeRectangle)) {
      throw new DeveloperError("options.nativeRectangle is required.");
    }
    if (!defined(options.skirtHeight)) {
      throw new DeveloperError("options.skirtHeight is required.");
    }
    //>>includeEnd('debug');

    // This function tends to be a performance hotspot for terrain rendering,
    // so it employs a lot of inlining and unrolling as an optimization.
    // In particular, the functionality of Ellipsoid.cartographicToCartesian
    // is inlined.

    var cos = Math.cos;
    var sin = Math.sin;
    var sqrt = Math.sqrt;
    var atan = Math.atan;
    var exp = Math.exp;
    var piOverTwo = CesiumMath.PI_OVER_TWO;
    var toRadians = CesiumMath.toRadians;

    var heightmap = options.heightmap;
    var width = options.width;
    var height = options.height;
    var skirtHeight = options.skirtHeight;

    var isGeographic = defaultValue(options.isGeographic, true);
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    var oneOverGlobeSemimajorAxis = 1.0 / ellipsoid.maximumRadius;

    var nativeRectangle = options.nativeRectangle;

    var geographicWest;
    var geographicSouth;
    var geographicEast;
    var geographicNorth;

    var rectangle = options.rectangle;
    if (!defined(rectangle)) {
      if (isGeographic) {
        geographicWest = toRadians(nativeRectangle.west);
        geographicSouth = toRadians(nativeRectangle.south);
        geographicEast = toRadians(nativeRectangle.east);
        geographicNorth = toRadians(nativeRectangle.north);
      } else {
        geographicWest = nativeRectangle.west * oneOverGlobeSemimajorAxis;
        geographicSouth =
          piOverTwo -
          2.0 * atan(exp(-nativeRectangle.south * oneOverGlobeSemimajorAxis));
        geographicEast = nativeRectangle.east * oneOverGlobeSemimajorAxis;
        geographicNorth =
          piOverTwo -
          2.0 * atan(exp(-nativeRectangle.north * oneOverGlobeSemimajorAxis));
      }
    } else {
      geographicWest = rectangle.west;
      geographicSouth = rectangle.south;
      geographicEast = rectangle.east;
      geographicNorth = rectangle.north;
    }

    var relativeToCenter = options.relativeToCenter;
    var hasRelativeToCenter = defined(relativeToCenter);
    relativeToCenter = hasRelativeToCenter ? relativeToCenter : Cartesian3.ZERO;
    var exaggeration = defaultValue(options.exaggeration, 1.0);
    var includeWebMercatorT = defaultValue(options.includeWebMercatorT, false);

    var structure = defaultValue(
      options.structure,
      HeightmapTessellator.DEFAULT_STRUCTURE
    );
    var heightScale = defaultValue(
      structure.heightScale,
      HeightmapTessellator.DEFAULT_STRUCTURE.heightScale
    );
    var heightOffset = defaultValue(
      structure.heightOffset,
      HeightmapTessellator.DEFAULT_STRUCTURE.heightOffset
    );
    var elementsPerHeight = defaultValue(
      structure.elementsPerHeight,
      HeightmapTessellator.DEFAULT_STRUCTURE.elementsPerHeight
    );
    var stride = defaultValue(
      structure.stride,
      HeightmapTessellator.DEFAULT_STRUCTURE.stride
    );
    var elementMultiplier = defaultValue(
      structure.elementMultiplier,
      HeightmapTessellator.DEFAULT_STRUCTURE.elementMultiplier
    );
    var isBigEndian = defaultValue(
      structure.isBigEndian,
      HeightmapTessellator.DEFAULT_STRUCTURE.isBigEndian
    );

    var rectangleWidth = Rectangle.computeWidth(nativeRectangle);
    var rectangleHeight = Rectangle.computeHeight(nativeRectangle);

    var granularityX = rectangleWidth / (width - 1);
    var granularityY = rectangleHeight / (height - 1);

    if (!isGeographic) {
      rectangleWidth *= oneOverGlobeSemimajorAxis;
      rectangleHeight *= oneOverGlobeSemimajorAxis;
    }

    var radiiSquared = ellipsoid.radiiSquared;
    var radiiSquaredX = radiiSquared.x;
    var radiiSquaredY = radiiSquared.y;
    var radiiSquaredZ = radiiSquared.z;

    var minimumHeight = 65536.0;
    var maximumHeight = -65536.0;

    var fromENU = Transforms.eastNorthUpToFixedFrame(relativeToCenter, ellipsoid);
    var toENU = Matrix4.inverseTransformation(fromENU, matrix4Scratch$1);

    var southMercatorY;
    var oneOverMercatorHeight;
    if (includeWebMercatorT) {
      southMercatorY = WebMercatorProjection.geodeticLatitudeToMercatorAngle(
        geographicSouth
      );
      oneOverMercatorHeight =
        1.0 /
        (WebMercatorProjection.geodeticLatitudeToMercatorAngle(geographicNorth) -
          southMercatorY);
    }

    var minimum = minimumScratch;
    minimum.x = Number.POSITIVE_INFINITY;
    minimum.y = Number.POSITIVE_INFINITY;
    minimum.z = Number.POSITIVE_INFINITY;

    var maximum = maximumScratch;
    maximum.x = Number.NEGATIVE_INFINITY;
    maximum.y = Number.NEGATIVE_INFINITY;
    maximum.z = Number.NEGATIVE_INFINITY;

    var hMin = Number.POSITIVE_INFINITY;

    var gridVertexCount = width * height;
    var edgeVertexCount = skirtHeight > 0.0 ? width * 2 + height * 2 : 0;
    var vertexCount = gridVertexCount + edgeVertexCount;

    var positions = new Array(vertexCount);
    var heights = new Array(vertexCount);
    var uvs = new Array(vertexCount);
    var webMercatorTs = includeWebMercatorT ? new Array(vertexCount) : [];

    var startRow = 0;
    var endRow = height;
    var startCol = 0;
    var endCol = width;

    if (skirtHeight > 0.0) {
      --startRow;
      ++endRow;
      --startCol;
      ++endCol;
    }

    var skirtOffsetPercentage = 0.00001;

    for (var rowIndex = startRow; rowIndex < endRow; ++rowIndex) {
      var row = rowIndex;
      if (row < 0) {
        row = 0;
      }
      if (row >= height) {
        row = height - 1;
      }

      var latitude = nativeRectangle.north - granularityY * row;

      if (!isGeographic) {
        latitude =
          piOverTwo - 2.0 * atan(exp(-latitude * oneOverGlobeSemimajorAxis));
      } else {
        latitude = toRadians(latitude);
      }

      var v = (latitude - geographicSouth) / (geographicNorth - geographicSouth);
      v = CesiumMath.clamp(v, 0.0, 1.0);

      var isNorthEdge = rowIndex === startRow;
      var isSouthEdge = rowIndex === endRow - 1;
      if (skirtHeight > 0.0) {
        if (isNorthEdge) {
          latitude += skirtOffsetPercentage * rectangleHeight;
        } else if (isSouthEdge) {
          latitude -= skirtOffsetPercentage * rectangleHeight;
        }
      }

      var cosLatitude = cos(latitude);
      var nZ = sin(latitude);
      var kZ = radiiSquaredZ * nZ;

      var webMercatorT;
      if (includeWebMercatorT) {
        webMercatorT =
          (WebMercatorProjection.geodeticLatitudeToMercatorAngle(latitude) -
            southMercatorY) *
          oneOverMercatorHeight;
      }

      for (var colIndex = startCol; colIndex < endCol; ++colIndex) {
        var col = colIndex;
        if (col < 0) {
          col = 0;
        }
        if (col >= width) {
          col = width - 1;
        }

        var terrainOffset = row * (width * stride) + col * stride;

        var heightSample;
        if (elementsPerHeight === 1) {
          heightSample = heightmap[terrainOffset];
        } else {
          heightSample = 0;

          var elementOffset;
          if (isBigEndian) {
            for (
              elementOffset = 0;
              elementOffset < elementsPerHeight;
              ++elementOffset
            ) {
              heightSample =
                heightSample * elementMultiplier +
                heightmap[terrainOffset + elementOffset];
            }
          } else {
            for (
              elementOffset = elementsPerHeight - 1;
              elementOffset >= 0;
              --elementOffset
            ) {
              heightSample =
                heightSample * elementMultiplier +
                heightmap[terrainOffset + elementOffset];
            }
          }
        }

        heightSample = (heightSample * heightScale + heightOffset) * exaggeration;

        maximumHeight = Math.max(maximumHeight, heightSample);
        minimumHeight = Math.min(minimumHeight, heightSample);

        var longitude = nativeRectangle.west + granularityX * col;

        if (!isGeographic) {
          longitude = longitude * oneOverGlobeSemimajorAxis;
        } else {
          longitude = toRadians(longitude);
        }

        var u = (longitude - geographicWest) / (geographicEast - geographicWest);
        u = CesiumMath.clamp(u, 0.0, 1.0);

        var index = row * width + col;

        if (skirtHeight > 0.0) {
          var isWestEdge = colIndex === startCol;
          var isEastEdge = colIndex === endCol - 1;
          var isEdge = isNorthEdge || isSouthEdge || isWestEdge || isEastEdge;
          var isCorner =
            (isNorthEdge || isSouthEdge) && (isWestEdge || isEastEdge);
          if (isCorner) {
            // Don't generate skirts on the corners.
            continue;
          } else if (isEdge) {
            heightSample -= skirtHeight;

            if (isWestEdge) {
              // The outer loop iterates north to south but the indices are ordered south to north, hence the index flip below
              index = gridVertexCount + (height - row - 1);
              longitude -= skirtOffsetPercentage * rectangleWidth;
            } else if (isSouthEdge) {
              // Add after west indices. South indices are ordered east to west.
              index = gridVertexCount + height + (width - col - 1);
            } else if (isEastEdge) {
              // Add after west and south indices. East indices are ordered north to south. The index is flipped like above.
              index = gridVertexCount + height + width + row;
              longitude += skirtOffsetPercentage * rectangleWidth;
            } else if (isNorthEdge) {
              // Add after west, south, and east indices. North indices are ordered west to east.
              index = gridVertexCount + height + width + height + col;
            }
          }
        }

        var nX = cosLatitude * cos(longitude);
        var nY = cosLatitude * sin(longitude);

        var kX = radiiSquaredX * nX;
        var kY = radiiSquaredY * nY;

        var gamma = sqrt(kX * nX + kY * nY + kZ * nZ);
        var oneOverGamma = 1.0 / gamma;

        var rSurfaceX = kX * oneOverGamma;
        var rSurfaceY = kY * oneOverGamma;
        var rSurfaceZ = kZ * oneOverGamma;

        var position = new Cartesian3();
        position.x = rSurfaceX + nX * heightSample;
        position.y = rSurfaceY + nY * heightSample;
        position.z = rSurfaceZ + nZ * heightSample;

        positions[index] = position;
        heights[index] = heightSample;
        uvs[index] = new Cartesian2(u, v);

        if (includeWebMercatorT) {
          webMercatorTs[index] = webMercatorT;
        }

        Matrix4.multiplyByPoint(toENU, position, cartesian3Scratch$1);

        Cartesian3.minimumByComponent(cartesian3Scratch$1, minimum, minimum);
        Cartesian3.maximumByComponent(cartesian3Scratch$1, maximum, maximum);
        hMin = Math.min(hMin, heightSample);
      }
    }

    var boundingSphere3D = BoundingSphere.fromPoints(positions);
    var orientedBoundingBox;
    if (defined(rectangle)) {
      orientedBoundingBox = OrientedBoundingBox.fromRectangle(
        rectangle,
        minimumHeight,
        maximumHeight,
        ellipsoid
      );
    }

    var occludeePointInScaledSpace;
    if (hasRelativeToCenter) {
      var occluder = new EllipsoidalOccluder(ellipsoid);
      occludeePointInScaledSpace = occluder.computeHorizonCullingPointPossiblyUnderEllipsoid(
        relativeToCenter,
        positions,
        minimumHeight
      );
    }

    var aaBox = new AxisAlignedBoundingBox(minimum, maximum, relativeToCenter);
    var encoding = new TerrainEncoding(
      aaBox,
      hMin,
      maximumHeight,
      fromENU,
      false,
      includeWebMercatorT
    );
    var vertices = new Float32Array(vertexCount * encoding.getStride());

    var bufferIndex = 0;
    for (var j = 0; j < vertexCount; ++j) {
      bufferIndex = encoding.encode(
        vertices,
        bufferIndex,
        positions[j],
        uvs[j],
        heights[j],
        undefined,
        webMercatorTs[j]
      );
    }

    return {
      vertices: vertices,
      maximumHeight: maximumHeight,
      minimumHeight: minimumHeight,
      encoding: encoding,
      boundingSphere3D: boundingSphere3D,
      orientedBoundingBox: orientedBoundingBox,
      occludeePointInScaledSpace: occludeePointInScaledSpace,
    };
  };

  function returnTrue() {
    return true;
  }

  /**
   * Destroys an object.  Each of the object's functions, including functions in its prototype,
   * is replaced with a function that throws a {@link DeveloperError}, except for the object's
   * <code>isDestroyed</code> function, which is set to a function that returns <code>true</code>.
   * The object's properties are removed with <code>delete</code>.
   * <br /><br />
   * This function is used by objects that hold native resources, e.g., WebGL resources, which
   * need to be explicitly released.  Client code calls an object's <code>destroy</code> function,
   * which then releases the native resource and calls <code>destroyObject</code> to put itself
   * in a destroyed state.
   *
   * @function
   *
   * @param {Object} object The object to destroy.
   * @param {String} [message] The message to include in the exception that is thrown if
   *                           a destroyed object's function is called.
   *
   *
   * @example
   * // How a texture would destroy itself.
   * this.destroy = function () {
   *     _gl.deleteTexture(_texture);
   *     return Cesium.destroyObject(this);
   * };
   *
   * @see DeveloperError
   */
  function destroyObject(object, message) {
    message = defaultValue(
      message,
      "This object was destroyed, i.e., destroy() was called."
    );

    function throwOnDestroyed() {
      //>>includeStart('debug', pragmas.debug);
      throw new DeveloperError(message);
      //>>includeEnd('debug');
    }

    for (var key in object) {
      if (typeof object[key] === "function") {
        object[key] = throwOnDestroyed;
      }
    }

    object.isDestroyed = returnTrue;

    return undefined;
  }

  function canTransferArrayBuffer() {
    if (!defined(TaskProcessor._canTransferArrayBuffer)) {
      var worker = new Worker(getWorkerUrl("Workers/transferTypedArrayTest.js"));
      worker.postMessage = defaultValue(
        worker.webkitPostMessage,
        worker.postMessage
      );

      var value = 99;
      var array = new Int8Array([value]);

      try {
        // postMessage might fail with a DataCloneError
        // if transferring array buffers is not supported.
        worker.postMessage(
          {
            array: array,
          },
          [array.buffer]
        );
      } catch (e) {
        TaskProcessor._canTransferArrayBuffer = false;
        return TaskProcessor._canTransferArrayBuffer;
      }

      var deferred = when.defer();

      worker.onmessage = function (event) {
        var array = event.data.array;

        // some versions of Firefox silently fail to transfer typed arrays.
        // https://bugzilla.mozilla.org/show_bug.cgi?id=841904
        // Check to make sure the value round-trips successfully.
        var result = defined(array) && array[0] === value;
        deferred.resolve(result);

        worker.terminate();

        TaskProcessor._canTransferArrayBuffer = result;
      };

      TaskProcessor._canTransferArrayBuffer = deferred.promise;
    }

    return TaskProcessor._canTransferArrayBuffer;
  }

  var taskCompletedEvent = new Event();

  function completeTask(processor, data) {
    --processor._activeTasks;

    var id = data.id;
    if (!defined(id)) {
      // This is not one of ours.
      return;
    }

    var deferreds = processor._deferreds;
    var deferred = deferreds[id];

    if (defined(data.error)) {
      var error = data.error;
      if (error.name === "RuntimeError") {
        error = new RuntimeError(data.error.message);
        error.stack = data.error.stack;
      } else if (error.name === "DeveloperError") {
        error = new DeveloperError(data.error.message);
        error.stack = data.error.stack;
      }
      taskCompletedEvent.raiseEvent(error);
      deferred.reject(error);
    } else {
      taskCompletedEvent.raiseEvent();
      deferred.resolve(data.result);
    }

    delete deferreds[id];
  }

  function getWorkerUrl(moduleID) {
    var url = buildModuleUrl(moduleID);

    if (isCrossOriginUrl(url)) {
      //to load cross-origin, create a shim worker from a blob URL
      var script = 'importScripts("' + url + '");';

      var blob;
      try {
        blob = new Blob([script], {
          type: "application/javascript",
        });
      } catch (e) {
        var BlobBuilder =
          window.BlobBuilder ||
          window.WebKitBlobBuilder ||
          window.MozBlobBuilder ||
          window.MSBlobBuilder;
        var blobBuilder = new BlobBuilder();
        blobBuilder.append(script);
        blob = blobBuilder.getBlob("application/javascript");
      }

      var URL = window.URL || window.webkitURL;
      url = URL.createObjectURL(blob);
    }

    return url;
  }

  var bootstrapperUrlResult;
  function getBootstrapperUrl() {
    if (!defined(bootstrapperUrlResult)) {
      bootstrapperUrlResult = getWorkerUrl("Workers/cesiumWorkerBootstrapper.js");
    }
    return bootstrapperUrlResult;
  }

  function createWorker(processor) {
    var worker = new Worker(getBootstrapperUrl());
    worker.postMessage = defaultValue(
      worker.webkitPostMessage,
      worker.postMessage
    );

    var bootstrapMessage = {
      loaderConfig: {
        paths: {
          Workers: buildModuleUrl("Workers"),
        },
        baseUrl: buildModuleUrl.getCesiumBaseUrl().url,
      },
      workerModule: TaskProcessor._workerModulePrefix + processor._workerName,
    };

    worker.postMessage(bootstrapMessage);
    worker.onmessage = function (event) {
      completeTask(processor, event.data);
    };

    return worker;
  }

  function getWebAssemblyLoaderConfig(processor, wasmOptions) {
    var config = {
      modulePath: undefined,
      wasmBinaryFile: undefined,
      wasmBinary: undefined,
    };

    // Web assembly not supported, use fallback js module if provided
    if (!FeatureDetection.supportsWebAssembly()) {
      if (!defined(wasmOptions.fallbackModulePath)) {
        throw new RuntimeError(
          "This browser does not support Web Assembly, and no backup module was provided for " +
            processor._workerName
        );
      }

      config.modulePath = buildModuleUrl(wasmOptions.fallbackModulePath);
      return when.resolve(config);
    }

    config.modulePath = buildModuleUrl(wasmOptions.modulePath);
    config.wasmBinaryFile = buildModuleUrl(wasmOptions.wasmBinaryFile);

    return Resource.fetchArrayBuffer({
      url: config.wasmBinaryFile,
    }).then(function (arrayBuffer) {
      config.wasmBinary = arrayBuffer;
      return config;
    });
  }

  /**
   * A wrapper around a web worker that allows scheduling tasks for a given worker,
   * returning results asynchronously via a promise.
   *
   * The Worker is not constructed until a task is scheduled.
   *
   * @alias TaskProcessor
   * @constructor
   *
   * @param {String} workerName The name of the worker.  This is expected to be a script
   *                            in the Workers folder.
   * @param {Number} [maximumActiveTasks=5] The maximum number of active tasks.  Once exceeded,
   *                                        scheduleTask will not queue any more tasks, allowing
   *                                        work to be rescheduled in future frames.
   */
  function TaskProcessor(workerName, maximumActiveTasks) {
    this._workerName = workerName;
    this._maximumActiveTasks = defaultValue(maximumActiveTasks, 5);
    this._activeTasks = 0;
    this._deferreds = {};
    this._nextID = 0;
  }

  var emptyTransferableObjectArray = [];

  /**
   * Schedule a task to be processed by the web worker asynchronously.  If there are currently more
   * tasks active than the maximum set by the constructor, will immediately return undefined.
   * Otherwise, returns a promise that will resolve to the result posted back by the worker when
   * finished.
   *
   * @param {Object} parameters Any input data that will be posted to the worker.
   * @param {Object[]} [transferableObjects] An array of objects contained in parameters that should be
   *                                      transferred to the worker instead of copied.
   * @returns {Promise.<Object>|undefined} Either a promise that will resolve to the result when available, or undefined
   *                    if there are too many active tasks,
   *
   * @example
   * var taskProcessor = new Cesium.TaskProcessor('myWorkerName');
   * var promise = taskProcessor.scheduleTask({
   *     someParameter : true,
   *     another : 'hello'
   * });
   * if (!Cesium.defined(promise)) {
   *     // too many active tasks - try again later
   * } else {
   *     Cesium.when(promise, function(result) {
   *         // use the result of the task
   *     });
   * }
   */
  TaskProcessor.prototype.scheduleTask = function (
    parameters,
    transferableObjects
  ) {
    if (!defined(this._worker)) {
      this._worker = createWorker(this);
    }

    if (this._activeTasks >= this._maximumActiveTasks) {
      return undefined;
    }

    ++this._activeTasks;

    var processor = this;
    return when(canTransferArrayBuffer(), function (canTransferArrayBuffer) {
      if (!defined(transferableObjects)) {
        transferableObjects = emptyTransferableObjectArray;
      } else if (!canTransferArrayBuffer) {
        transferableObjects.length = 0;
      }

      var id = processor._nextID++;
      var deferred = when.defer();
      processor._deferreds[id] = deferred;

      processor._worker.postMessage(
        {
          id: id,
          parameters: parameters,
          canTransferArrayBuffer: canTransferArrayBuffer,
        },
        transferableObjects
      );

      return deferred.promise;
    });
  };

  /**
   * Posts a message to a web worker with configuration to initialize loading
   * and compiling a web assembly module asychronously, as well as an optional
   * fallback JavaScript module to use if Web Assembly is not supported.
   *
   * @param {Object} [webAssemblyOptions] An object with the following properties:
   * @param {String} [webAssemblyOptions.modulePath] The path of the web assembly JavaScript wrapper module.
   * @param {String} [webAssemblyOptions.wasmBinaryFile] The path of the web assembly binary file.
   * @param {String} [webAssemblyOptions.fallbackModulePath] The path of the fallback JavaScript module to use if web assembly is not supported.
   * @returns {Promise.<Object>} A promise that resolves to the result when the web worker has loaded and compiled the web assembly module and is ready to process tasks.
   */
  TaskProcessor.prototype.initWebAssemblyModule = function (webAssemblyOptions) {
    if (!defined(this._worker)) {
      this._worker = createWorker(this);
    }

    var deferred = when.defer();
    var processor = this;
    var worker = this._worker;
    getWebAssemblyLoaderConfig(this, webAssemblyOptions).then(function (
      wasmConfig
    ) {
      return when(canTransferArrayBuffer(), function (canTransferArrayBuffer) {
        var transferableObjects;
        var binary = wasmConfig.wasmBinary;
        if (defined(binary) && canTransferArrayBuffer) {
          transferableObjects = [binary];
        }

        worker.onmessage = function (event) {
          worker.onmessage = function (event) {
            completeTask(processor, event.data);
          };

          deferred.resolve(event.data);
        };

        worker.postMessage(
          { webAssemblyConfig: wasmConfig },
          transferableObjects
        );
      });
    });

    return deferred;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see TaskProcessor#destroy
   */
  TaskProcessor.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys this object.  This will immediately terminate the Worker.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   */
  TaskProcessor.prototype.destroy = function () {
    if (defined(this._worker)) {
      this._worker.terminate();
    }
    return destroyObject(this);
  };

  /**
   * An event that's raised when a task is completed successfully.  Event handlers are passed
   * the error object is a task fails.
   *
   * @type {Event}
   *
   * @private
   */
  TaskProcessor.taskCompletedEvent = taskCompletedEvent;

  // exposed for testing purposes
  TaskProcessor._defaultWorkerModulePrefix = "Workers/";
  TaskProcessor._workerModulePrefix = TaskProcessor._defaultWorkerModulePrefix;
  TaskProcessor._canTransferArrayBuffer = undefined;

  /**
   * A mesh plus related metadata for a single tile of terrain.  Instances of this type are
   * usually created from raw {@link TerrainData}.
   *
   * @alias TerrainMesh
   * @constructor
   *
   * @param {Cartesian3} center The center of the tile.  Vertex positions are specified relative to this center.
   * @param {Float32Array} vertices The vertex data, including positions, texture coordinates, and heights.
   *                       The vertex data is in the order [X, Y, Z, H, U, V], where X, Y, and Z represent
   *                       the Cartesian position of the vertex, H is the height above the ellipsoid, and
   *                       U and V are the texture coordinates.
   * @param {Uint8Array|Uint16Array|Uint32Array} indices The indices describing how the vertices are connected to form triangles.
   * @param {Number} indexCountWithoutSkirts The index count of the mesh not including skirts.
   * @param {Number} vertexCountWithoutSkirts The vertex count of the mesh not including skirts.
   * @param {Number} minimumHeight The lowest height in the tile, in meters above the ellipsoid.
   * @param {Number} maximumHeight The highest height in the tile, in meters above the ellipsoid.
   * @param {BoundingSphere} boundingSphere3D A bounding sphere that completely contains the tile.
   * @param {Cartesian3} occludeePointInScaledSpace The occludee point of the tile, represented in ellipsoid-
   *                     scaled space, and used for horizon culling.  If this point is below the horizon,
   *                     the tile is considered to be entirely below the horizon.
   * @param {Number} [vertexStride=6] The number of components in each vertex.
   * @param {OrientedBoundingBox} [orientedBoundingBox] A bounding box that completely contains the tile.
   * @param {TerrainEncoding} encoding Information used to decode the mesh.
   * @param {Number} exaggeration The amount that this mesh was exaggerated.
   * @param {Number[]} westIndicesSouthToNorth The indices of the vertices on the Western edge of the tile, ordered from South to North (clockwise).
   * @param {Number[]} southIndicesEastToWest The indices of the vertices on the Southern edge of the tile, ordered from East to West (clockwise).
   * @param {Number[]} eastIndicesNorthToSouth The indices of the vertices on the Eastern edge of the tile, ordered from North to South (clockwise).
   * @param {Number[]} northIndicesWestToEast The indices of the vertices on the Northern edge of the tile, ordered from West to East (clockwise).
   *
   * @private
   */
  function TerrainMesh(
    center,
    vertices,
    indices,
    indexCountWithoutSkirts,
    vertexCountWithoutSkirts,
    minimumHeight,
    maximumHeight,
    boundingSphere3D,
    occludeePointInScaledSpace,
    vertexStride,
    orientedBoundingBox,
    encoding,
    exaggeration,
    westIndicesSouthToNorth,
    southIndicesEastToWest,
    eastIndicesNorthToSouth,
    northIndicesWestToEast
  ) {
    /**
     * The center of the tile.  Vertex positions are specified relative to this center.
     * @type {Cartesian3}
     */
    this.center = center;

    /**
     * The vertex data, including positions, texture coordinates, and heights.
     * The vertex data is in the order [X, Y, Z, H, U, V], where X, Y, and Z represent
     * the Cartesian position of the vertex, H is the height above the ellipsoid, and
     * U and V are the texture coordinates.  The vertex data may have additional attributes after those
     * mentioned above when the {@link TerrainMesh#stride} is greater than 6.
     * @type {Float32Array}
     */
    this.vertices = vertices;

    /**
     * The number of components in each vertex.  Typically this is 6 for the 6 components
     * [X, Y, Z, H, U, V], but if each vertex has additional data (such as a vertex normal), this value
     * may be higher.
     * @type {Number}
     */
    this.stride = defaultValue(vertexStride, 6);

    /**
     * The indices describing how the vertices are connected to form triangles.
     * @type {Uint8Array|Uint16Array|Uint32Array}
     */
    this.indices = indices;

    /**
     * The index count of the mesh not including skirts.
     * @type {Number}
     */
    this.indexCountWithoutSkirts = indexCountWithoutSkirts;

    /**
     * The vertex count of the mesh not including skirts.
     * @type {Number}
     */
    this.vertexCountWithoutSkirts = vertexCountWithoutSkirts;

    /**
     * The lowest height in the tile, in meters above the ellipsoid.
     * @type {Number}
     */
    this.minimumHeight = minimumHeight;

    /**
     * The highest height in the tile, in meters above the ellipsoid.
     * @type {Number}
     */
    this.maximumHeight = maximumHeight;

    /**
     * A bounding sphere that completely contains the tile.
     * @type {BoundingSphere}
     */
    this.boundingSphere3D = boundingSphere3D;

    /**
     * The occludee point of the tile, represented in ellipsoid-
     * scaled space, and used for horizon culling.  If this point is below the horizon,
     * the tile is considered to be entirely below the horizon.
     * @type {Cartesian3}
     */
    this.occludeePointInScaledSpace = occludeePointInScaledSpace;

    /**
     * A bounding box that completely contains the tile.
     * @type {OrientedBoundingBox}
     */
    this.orientedBoundingBox = orientedBoundingBox;

    /**
     * Information for decoding the mesh vertices.
     * @type {TerrainEncoding}
     */
    this.encoding = encoding;

    /**
     * The amount that this mesh was exaggerated.
     * @type {Number}
     */
    this.exaggeration = exaggeration;

    /**
     * The indices of the vertices on the Western edge of the tile, ordered from South to North (clockwise).
     * @type {Number[]}
     */
    this.westIndicesSouthToNorth = westIndicesSouthToNorth;

    /**
     * The indices of the vertices on the Southern edge of the tile, ordered from East to West (clockwise).
     * @type {Number[]}
     */
    this.southIndicesEastToWest = southIndicesEastToWest;

    /**
     * The indices of the vertices on the Eastern edge of the tile, ordered from North to South (clockwise).
     * @type {Number[]}
     */
    this.eastIndicesNorthToSouth = eastIndicesNorthToSouth;

    /**
     * The indices of the vertices on the Northern edge of the tile, ordered from West to East (clockwise).
     * @type {Number[]}
     */
    this.northIndicesWestToEast = northIndicesWestToEast;
  }

  /**
   * Constants for WebGL index datatypes.  These corresponds to the
   * <code>type</code> parameter of {@link http://www.khronos.org/opengles/sdk/docs/man/xhtml/glDrawElements.xml|drawElements}.
   *
   * @enum {Number}
   */
  var IndexDatatype = {
    /**
     * 8-bit unsigned byte corresponding to <code>UNSIGNED_BYTE</code> and the type
     * of an element in <code>Uint8Array</code>.
     *
     * @type {Number}
     * @constant
     */
    UNSIGNED_BYTE: WebGLConstants$1.UNSIGNED_BYTE,

    /**
     * 16-bit unsigned short corresponding to <code>UNSIGNED_SHORT</code> and the type
     * of an element in <code>Uint16Array</code>.
     *
     * @type {Number}
     * @constant
     */
    UNSIGNED_SHORT: WebGLConstants$1.UNSIGNED_SHORT,

    /**
     * 32-bit unsigned int corresponding to <code>UNSIGNED_INT</code> and the type
     * of an element in <code>Uint32Array</code>.
     *
     * @type {Number}
     * @constant
     */
    UNSIGNED_INT: WebGLConstants$1.UNSIGNED_INT,
  };

  /**
   * Returns the size, in bytes, of the corresponding datatype.
   *
   * @param {IndexDatatype} indexDatatype The index datatype to get the size of.
   * @returns {Number} The size in bytes.
   *
   * @example
   * // Returns 2
   * var size = Cesium.IndexDatatype.getSizeInBytes(Cesium.IndexDatatype.UNSIGNED_SHORT);
   */
  IndexDatatype.getSizeInBytes = function (indexDatatype) {
    switch (indexDatatype) {
      case IndexDatatype.UNSIGNED_BYTE:
        return Uint8Array.BYTES_PER_ELEMENT;
      case IndexDatatype.UNSIGNED_SHORT:
        return Uint16Array.BYTES_PER_ELEMENT;
      case IndexDatatype.UNSIGNED_INT:
        return Uint32Array.BYTES_PER_ELEMENT;
    }

    //>>includeStart('debug', pragmas.debug);
    throw new DeveloperError(
      "indexDatatype is required and must be a valid IndexDatatype constant."
    );
    //>>includeEnd('debug');
  };

  /**
   * Gets the datatype with a given size in bytes.
   *
   * @param {Number} sizeInBytes The size of a single index in bytes.
   * @returns {IndexDatatype} The index datatype with the given size.
   */
  IndexDatatype.fromSizeInBytes = function (sizeInBytes) {
    switch (sizeInBytes) {
      case 2:
        return IndexDatatype.UNSIGNED_SHORT;
      case 4:
        return IndexDatatype.UNSIGNED_INT;
      case 1:
        return IndexDatatype.UNSIGNED_BYTE;
      //>>includeStart('debug', pragmas.debug);
      default:
        throw new DeveloperError(
          "Size in bytes cannot be mapped to an IndexDatatype"
        );
      //>>includeEnd('debug');
    }
  };

  /**
   * Validates that the provided index datatype is a valid {@link IndexDatatype}.
   *
   * @param {IndexDatatype} indexDatatype The index datatype to validate.
   * @returns {Boolean} <code>true</code> if the provided index datatype is a valid value; otherwise, <code>false</code>.
   *
   * @example
   * if (!Cesium.IndexDatatype.validate(indexDatatype)) {
   *   throw new Cesium.DeveloperError('indexDatatype must be a valid value.');
   * }
   */
  IndexDatatype.validate = function (indexDatatype) {
    return (
      defined(indexDatatype) &&
      (indexDatatype === IndexDatatype.UNSIGNED_BYTE ||
        indexDatatype === IndexDatatype.UNSIGNED_SHORT ||
        indexDatatype === IndexDatatype.UNSIGNED_INT)
    );
  };

  /**
   * Creates a typed array that will store indices, using either <code><Uint16Array</code>
   * or <code>Uint32Array</code> depending on the number of vertices.
   *
   * @param {Number} numberOfVertices Number of vertices that the indices will reference.
   * @param {Number|Array} indicesLengthOrArray Passed through to the typed array constructor.
   * @returns {Uint16Array|Uint32Array} A <code>Uint16Array</code> or <code>Uint32Array</code> constructed with <code>indicesLengthOrArray</code>.
   *
   * @example
   * this.indices = Cesium.IndexDatatype.createTypedArray(positions.length / 3, numberOfIndices);
   */
  IndexDatatype.createTypedArray = function (
    numberOfVertices,
    indicesLengthOrArray
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(numberOfVertices)) {
      throw new DeveloperError("numberOfVertices is required.");
    }
    //>>includeEnd('debug');

    if (numberOfVertices >= CesiumMath.SIXTY_FOUR_KILOBYTES) {
      return new Uint32Array(indicesLengthOrArray);
    }

    return new Uint16Array(indicesLengthOrArray);
  };

  /**
   * Creates a typed array from a source array buffer.  The resulting typed array will store indices, using either <code><Uint16Array</code>
   * or <code>Uint32Array</code> depending on the number of vertices.
   *
   * @param {Number} numberOfVertices Number of vertices that the indices will reference.
   * @param {ArrayBuffer} sourceArray Passed through to the typed array constructor.
   * @param {Number} byteOffset Passed through to the typed array constructor.
   * @param {Number} length Passed through to the typed array constructor.
   * @returns {Uint16Array|Uint32Array} A <code>Uint16Array</code> or <code>Uint32Array</code> constructed with <code>sourceArray</code>, <code>byteOffset</code>, and <code>length</code>.
   *
   */
  IndexDatatype.createTypedArrayFromArrayBuffer = function (
    numberOfVertices,
    sourceArray,
    byteOffset,
    length
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(numberOfVertices)) {
      throw new DeveloperError("numberOfVertices is required.");
    }
    if (!defined(sourceArray)) {
      throw new DeveloperError("sourceArray is required.");
    }
    if (!defined(byteOffset)) {
      throw new DeveloperError("byteOffset is required.");
    }
    //>>includeEnd('debug');

    if (numberOfVertices >= CesiumMath.SIXTY_FOUR_KILOBYTES) {
      return new Uint32Array(sourceArray, byteOffset, length);
    }

    return new Uint16Array(sourceArray, byteOffset, length);
  };
  var IndexDatatype$1 = Object.freeze(IndexDatatype);

  /**
   * Provides terrain or other geometry for the surface of an ellipsoid.  The surface geometry is
   * organized into a pyramid of tiles according to a {@link TilingScheme}.  This type describes an
   * interface and is not intended to be instantiated directly.
   *
   * @alias TerrainProvider
   * @constructor
   *
   * @see EllipsoidTerrainProvider
   * @see CesiumTerrainProvider
   * @see VRTheWorldTerrainProvider
   * @see GoogleEarthEnterpriseTerrainProvider
   */
  function TerrainProvider() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(TerrainProvider.prototype, {
    /**
     * Gets an event that is raised when the terrain provider encounters an asynchronous error..  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof TerrainProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the credit to display when this terrain provider is active.  Typically this is used to credit
     * the source of the terrain. This function should
     * not be called before {@link TerrainProvider#ready} returns true.
     * @memberof TerrainProvider.prototype
     * @type {Credit}
     */
    credit: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the tiling scheme used by the provider.  This function should
     * not be called before {@link TerrainProvider#ready} returns true.
     * @memberof TerrainProvider.prototype
     * @type {TilingScheme}
     */
    tilingScheme: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof TerrainProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof TerrainProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a value indicating whether or not the provider includes a water mask.  The water mask
     * indicates which areas of the globe are water rather than land, so they can be rendered
     * as a reflective surface with animated waves.  This function should not be
     * called before {@link TerrainProvider#ready} returns true.
     * @memberof TerrainProvider.prototype
     * @type {Boolean}
     */
    hasWaterMask: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a value indicating whether or not the requested tiles include vertex normals.
     * This function should not be called before {@link TerrainProvider#ready} returns true.
     * @memberof TerrainProvider.prototype
     * @type {Boolean}
     */
    hasVertexNormals: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets an object that can be used to determine availability of terrain from this provider, such as
     * at points and in rectangles.  This function should not be called before
     * {@link TerrainProvider#ready} returns true.  This property may be undefined if availability
     * information is not available.
     * @memberof TerrainProvider.prototype
     * @type {TileAvailability}
     */
    availability: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  var regularGridIndicesCache = [];

  /**
   * Gets a list of indices for a triangle mesh representing a regular grid.  Calling
   * this function multiple times with the same grid width and height returns the
   * same list of indices.  The total number of vertices must be less than or equal
   * to 65536.
   *
   * @param {Number} width The number of vertices in the regular grid in the horizontal direction.
   * @param {Number} height The number of vertices in the regular grid in the vertical direction.
   * @returns {Uint16Array|Uint32Array} The list of indices. Uint16Array gets returned for 64KB or less and Uint32Array for 4GB or less.
   */
  TerrainProvider.getRegularGridIndices = function (width, height) {
    //>>includeStart('debug', pragmas.debug);
    if (width * height >= CesiumMath.FOUR_GIGABYTES) {
      throw new DeveloperError(
        "The total number of vertices (width * height) must be less than 4,294,967,296."
      );
    }
    //>>includeEnd('debug');

    var byWidth = regularGridIndicesCache[width];
    if (!defined(byWidth)) {
      regularGridIndicesCache[width] = byWidth = [];
    }

    var indices = byWidth[height];
    if (!defined(indices)) {
      if (width * height < CesiumMath.SIXTY_FOUR_KILOBYTES) {
        indices = byWidth[height] = new Uint16Array(
          (width - 1) * (height - 1) * 6
        );
      } else {
        indices = byWidth[height] = new Uint32Array(
          (width - 1) * (height - 1) * 6
        );
      }
      addRegularGridIndices(width, height, indices, 0);
    }

    return indices;
  };

  var regularGridAndEdgeIndicesCache = [];

  /**
   * @private
   */
  TerrainProvider.getRegularGridIndicesAndEdgeIndices = function (width, height) {
    //>>includeStart('debug', pragmas.debug);
    if (width * height >= CesiumMath.FOUR_GIGABYTES) {
      throw new DeveloperError(
        "The total number of vertices (width * height) must be less than 4,294,967,296."
      );
    }
    //>>includeEnd('debug');

    var byWidth = regularGridAndEdgeIndicesCache[width];
    if (!defined(byWidth)) {
      regularGridAndEdgeIndicesCache[width] = byWidth = [];
    }

    var indicesAndEdges = byWidth[height];
    if (!defined(indicesAndEdges)) {
      var indices = TerrainProvider.getRegularGridIndices(width, height);

      var edgeIndices = getEdgeIndices(width, height);
      var westIndicesSouthToNorth = edgeIndices.westIndicesSouthToNorth;
      var southIndicesEastToWest = edgeIndices.southIndicesEastToWest;
      var eastIndicesNorthToSouth = edgeIndices.eastIndicesNorthToSouth;
      var northIndicesWestToEast = edgeIndices.northIndicesWestToEast;

      indicesAndEdges = byWidth[height] = {
        indices: indices,
        westIndicesSouthToNorth: westIndicesSouthToNorth,
        southIndicesEastToWest: southIndicesEastToWest,
        eastIndicesNorthToSouth: eastIndicesNorthToSouth,
        northIndicesWestToEast: northIndicesWestToEast,
      };
    }

    return indicesAndEdges;
  };

  var regularGridAndSkirtAndEdgeIndicesCache = [];

  /**
   * @private
   */
  TerrainProvider.getRegularGridAndSkirtIndicesAndEdgeIndices = function (
    width,
    height
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (width * height >= CesiumMath.FOUR_GIGABYTES) {
      throw new DeveloperError(
        "The total number of vertices (width * height) must be less than 4,294,967,296."
      );
    }
    //>>includeEnd('debug');

    var byWidth = regularGridAndSkirtAndEdgeIndicesCache[width];
    if (!defined(byWidth)) {
      regularGridAndSkirtAndEdgeIndicesCache[width] = byWidth = [];
    }

    var indicesAndEdges = byWidth[height];
    if (!defined(indicesAndEdges)) {
      var gridVertexCount = width * height;
      var gridIndexCount = (width - 1) * (height - 1) * 6;
      var edgeVertexCount = width * 2 + height * 2;
      var edgeIndexCount = Math.max(0, edgeVertexCount - 4) * 6;
      var vertexCount = gridVertexCount + edgeVertexCount;
      var indexCount = gridIndexCount + edgeIndexCount;

      var edgeIndices = getEdgeIndices(width, height);
      var westIndicesSouthToNorth = edgeIndices.westIndicesSouthToNorth;
      var southIndicesEastToWest = edgeIndices.southIndicesEastToWest;
      var eastIndicesNorthToSouth = edgeIndices.eastIndicesNorthToSouth;
      var northIndicesWestToEast = edgeIndices.northIndicesWestToEast;

      var indices = IndexDatatype$1.createTypedArray(vertexCount, indexCount);
      addRegularGridIndices(width, height, indices, 0);
      TerrainProvider.addSkirtIndices(
        westIndicesSouthToNorth,
        southIndicesEastToWest,
        eastIndicesNorthToSouth,
        northIndicesWestToEast,
        gridVertexCount,
        indices,
        gridIndexCount
      );

      indicesAndEdges = byWidth[height] = {
        indices: indices,
        westIndicesSouthToNorth: westIndicesSouthToNorth,
        southIndicesEastToWest: southIndicesEastToWest,
        eastIndicesNorthToSouth: eastIndicesNorthToSouth,
        northIndicesWestToEast: northIndicesWestToEast,
        indexCountWithoutSkirts: gridIndexCount,
      };
    }

    return indicesAndEdges;
  };

  /**
   * @private
   */
  TerrainProvider.addSkirtIndices = function (
    westIndicesSouthToNorth,
    southIndicesEastToWest,
    eastIndicesNorthToSouth,
    northIndicesWestToEast,
    vertexCount,
    indices,
    offset
  ) {
    var vertexIndex = vertexCount;
    offset = addSkirtIndices(
      westIndicesSouthToNorth,
      vertexIndex,
      indices,
      offset
    );
    vertexIndex += westIndicesSouthToNorth.length;
    offset = addSkirtIndices(
      southIndicesEastToWest,
      vertexIndex,
      indices,
      offset
    );
    vertexIndex += southIndicesEastToWest.length;
    offset = addSkirtIndices(
      eastIndicesNorthToSouth,
      vertexIndex,
      indices,
      offset
    );
    vertexIndex += eastIndicesNorthToSouth.length;
    addSkirtIndices(northIndicesWestToEast, vertexIndex, indices, offset);
  };

  function getEdgeIndices(width, height) {
    var westIndicesSouthToNorth = new Array(height);
    var southIndicesEastToWest = new Array(width);
    var eastIndicesNorthToSouth = new Array(height);
    var northIndicesWestToEast = new Array(width);

    var i;
    for (i = 0; i < width; ++i) {
      northIndicesWestToEast[i] = i;
      southIndicesEastToWest[i] = width * height - 1 - i;
    }

    for (i = 0; i < height; ++i) {
      eastIndicesNorthToSouth[i] = (i + 1) * width - 1;
      westIndicesSouthToNorth[i] = (height - i - 1) * width;
    }

    return {
      westIndicesSouthToNorth: westIndicesSouthToNorth,
      southIndicesEastToWest: southIndicesEastToWest,
      eastIndicesNorthToSouth: eastIndicesNorthToSouth,
      northIndicesWestToEast: northIndicesWestToEast,
    };
  }

  function addRegularGridIndices(width, height, indices, offset) {
    var index = 0;
    for (var j = 0; j < height - 1; ++j) {
      for (var i = 0; i < width - 1; ++i) {
        var upperLeft = index;
        var lowerLeft = upperLeft + width;
        var lowerRight = lowerLeft + 1;
        var upperRight = upperLeft + 1;

        indices[offset++] = upperLeft;
        indices[offset++] = lowerLeft;
        indices[offset++] = upperRight;
        indices[offset++] = upperRight;
        indices[offset++] = lowerLeft;
        indices[offset++] = lowerRight;

        ++index;
      }
      ++index;
    }
  }

  function addSkirtIndices(edgeIndices, vertexIndex, indices, offset) {
    var previousIndex = edgeIndices[0];

    var length = edgeIndices.length;
    for (var i = 1; i < length; ++i) {
      var index = edgeIndices[i];

      indices[offset++] = previousIndex;
      indices[offset++] = index;
      indices[offset++] = vertexIndex;

      indices[offset++] = vertexIndex;
      indices[offset++] = index;
      indices[offset++] = vertexIndex + 1;

      previousIndex = index;
      ++vertexIndex;
    }

    return offset;
  }

  /**
   * Specifies the quality of terrain created from heightmaps.  A value of 1.0 will
   * ensure that adjacent heightmap vertices are separated by no more than
   * {@link Globe.maximumScreenSpaceError} screen pixels and will probably go very slowly.
   * A value of 0.5 will cut the estimated level zero geometric error in half, allowing twice the
   * screen pixels between adjacent heightmap vertices and thus rendering more quickly.
   * @type {Number}
   */
  TerrainProvider.heightmapTerrainQuality = 0.25;

  /**
   * Determines an appropriate geometric error estimate when the geometry comes from a heightmap.
   *
   * @param {Ellipsoid} ellipsoid The ellipsoid to which the terrain is attached.
   * @param {Number} tileImageWidth The width, in pixels, of the heightmap associated with a single tile.
   * @param {Number} numberOfTilesAtLevelZero The number of tiles in the horizontal direction at tile level zero.
   * @returns {Number} An estimated geometric error.
   */
  TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap = function (
    ellipsoid,
    tileImageWidth,
    numberOfTilesAtLevelZero
  ) {
    return (
      (ellipsoid.maximumRadius *
        2 *
        Math.PI *
        TerrainProvider.heightmapTerrainQuality) /
      (tileImageWidth * numberOfTilesAtLevelZero)
    );
  };

  /**
   * Requests the geometry for a given tile.  This function should not be called before
   * {@link TerrainProvider#ready} returns true.  The result must include terrain data and
   * may optionally include a water mask and an indication of which child tiles are available.
   * @function
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @param {Request} [request] The request object. Intended for internal use only.
   *
   * @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry.  If this method
   *          returns undefined instead of a promise, it is an indication that too many requests are already
   *          pending and the request will be retried later.
   */
  TerrainProvider.prototype.requestTileGeometry =
    DeveloperError.throwInstantiationError;

  /**
   * Gets the maximum geometric error allowed in a tile at a given level.  This function should not be
   * called before {@link TerrainProvider#ready} returns true.
   * @function
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error.
   */
  TerrainProvider.prototype.getLevelMaximumGeometricError =
    DeveloperError.throwInstantiationError;

  /**
   * Determines whether data for a tile is available to be loaded.
   * @function
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {Boolean} Undefined if not supported by the terrain provider, otherwise true or false.
   */
  TerrainProvider.prototype.getTileDataAvailable =
    DeveloperError.throwInstantiationError;

  /**
   * Makes sure we load availability data for a tile
   * @function
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {undefined|Promise<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
   */
  TerrainProvider.prototype.loadTileDataAvailability =
    DeveloperError.throwInstantiationError;

  /**
   * Terrain data for a single tile where the terrain data is represented as a heightmap.  A heightmap
   * is a rectangular array of heights in row-major order from north to south and west to east.
   *
   * @alias HeightmapTerrainData
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} options.buffer The buffer containing height data.
   * @param {Number} options.width The width (longitude direction) of the heightmap, in samples.
   * @param {Number} options.height The height (latitude direction) of the heightmap, in samples.
   * @param {Number} [options.childTileMask=15] A bit mask indicating which of this tile's four children exist.
   *                 If a child's bit is set, geometry will be requested for that tile as well when it
   *                 is needed.  If the bit is cleared, the child tile is not requested and geometry is
   *                 instead upsampled from the parent.  The bit values are as follows:
   *                 <table>
   *                  <tr><th>Bit Position</th><th>Bit Value</th><th>Child Tile</th></tr>
   *                  <tr><td>0</td><td>1</td><td>Southwest</td></tr>
   *                  <tr><td>1</td><td>2</td><td>Southeast</td></tr>
   *                  <tr><td>2</td><td>4</td><td>Northwest</td></tr>
   *                  <tr><td>3</td><td>8</td><td>Northeast</td></tr>
   *                 </table>
   * @param {Uint8Array} [options.waterMask] The water mask included in this terrain data, if any.  A water mask is a square
   *                     Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
   *                     Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
   * @param {Object} [options.structure] An object describing the structure of the height data.
   * @param {Number} [options.structure.heightScale=1.0] The factor by which to multiply height samples in order to obtain
   *                 the height above the heightOffset, in meters.  The heightOffset is added to the resulting
   *                 height after multiplying by the scale.
   * @param {Number} [options.structure.heightOffset=0.0] The offset to add to the scaled height to obtain the final
   *                 height in meters.  The offset is added after the height sample is multiplied by the
   *                 heightScale.
   * @param {Number} [options.structure.elementsPerHeight=1] The number of elements in the buffer that make up a single height
   *                 sample.  This is usually 1, indicating that each element is a separate height sample.  If
   *                 it is greater than 1, that number of elements together form the height sample, which is
   *                 computed according to the structure.elementMultiplier and structure.isBigEndian properties.
   * @param {Number} [options.structure.stride=1] The number of elements to skip to get from the first element of
   *                 one height to the first element of the next height.
   * @param {Number} [options.structure.elementMultiplier=256.0] The multiplier used to compute the height value when the
   *                 stride property is greater than 1.  For example, if the stride is 4 and the strideMultiplier
   *                 is 256, the height is computed as follows:
   *                 `height = buffer[index] + buffer[index + 1] * 256 + buffer[index + 2] * 256 * 256 + buffer[index + 3] * 256 * 256 * 256`
   *                 This is assuming that the isBigEndian property is false.  If it is true, the order of the
   *                 elements is reversed.
   * @param {Boolean} [options.structure.isBigEndian=false] Indicates endianness of the elements in the buffer when the
   *                  stride property is greater than 1.  If this property is false, the first element is the
   *                  low-order element.  If it is true, the first element is the high-order element.
   * @param {Number} [options.structure.lowestEncodedHeight] The lowest value that can be stored in the height buffer.  Any heights that are lower
   *                 than this value after encoding with the `heightScale` and `heightOffset` are clamped to this value.  For example, if the height
   *                 buffer is a `Uint16Array`, this value should be 0 because a `Uint16Array` cannot store negative numbers.  If this parameter is
   *                 not specified, no minimum value is enforced.
   * @param {Number} [options.structure.highestEncodedHeight] The highest value that can be stored in the height buffer.  Any heights that are higher
   *                 than this value after encoding with the `heightScale` and `heightOffset` are clamped to this value.  For example, if the height
   *                 buffer is a `Uint16Array`, this value should be `256 * 256 - 1` or 65535 because a `Uint16Array` cannot store numbers larger
   *                 than 65535.  If this parameter is not specified, no maximum value is enforced.
   * @param {HeightmapEncoding} [options.encoding=HeightmapEncoding.NONE] The encoding that is used on the buffer.
   * @param {Boolean} [options.createdByUpsampling=false] True if this instance was created by upsampling another instance;
   *                  otherwise, false.
   *
   *
   * @example
   * var buffer = ...
   * var heightBuffer = new Uint16Array(buffer, 0, that._heightmapWidth * that._heightmapWidth);
   * var childTileMask = new Uint8Array(buffer, heightBuffer.byteLength, 1)[0];
   * var waterMask = new Uint8Array(buffer, heightBuffer.byteLength + 1, buffer.byteLength - heightBuffer.byteLength - 1);
   * var terrainData = new Cesium.HeightmapTerrainData({
   *   buffer : heightBuffer,
   *   width : 65,
   *   height : 65,
   *   childTileMask : childTileMask,
   *   waterMask : waterMask
   * });
   *
   * @see TerrainData
   * @see QuantizedMeshTerrainData
   * @see GoogleEarthEnterpriseTerrainData
   */
  function HeightmapTerrainData(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.buffer)) {
      throw new DeveloperError("options.buffer is required.");
    }
    if (!defined(options.width)) {
      throw new DeveloperError("options.width is required.");
    }
    if (!defined(options.height)) {
      throw new DeveloperError("options.height is required.");
    }
    //>>includeEnd('debug');

    this._buffer = options.buffer;
    this._width = options.width;
    this._height = options.height;
    this._childTileMask = defaultValue(options.childTileMask, 15);
    this._encoding = defaultValue(options.encoding, HeightmapEncoding$1.NONE);

    var defaultStructure = HeightmapTessellator.DEFAULT_STRUCTURE;
    var structure = options.structure;
    if (!defined(structure)) {
      structure = defaultStructure;
    } else if (structure !== defaultStructure) {
      structure.heightScale = defaultValue(
        structure.heightScale,
        defaultStructure.heightScale
      );
      structure.heightOffset = defaultValue(
        structure.heightOffset,
        defaultStructure.heightOffset
      );
      structure.elementsPerHeight = defaultValue(
        structure.elementsPerHeight,
        defaultStructure.elementsPerHeight
      );
      structure.stride = defaultValue(structure.stride, defaultStructure.stride);
      structure.elementMultiplier = defaultValue(
        structure.elementMultiplier,
        defaultStructure.elementMultiplier
      );
      structure.isBigEndian = defaultValue(
        structure.isBigEndian,
        defaultStructure.isBigEndian
      );
    }

    this._structure = structure;
    this._createdByUpsampling = defaultValue(options.createdByUpsampling, false);
    this._waterMask = options.waterMask;

    this._skirtHeight = undefined;
    this._bufferType =
      this._encoding === HeightmapEncoding$1.LERC
        ? Float32Array
        : this._buffer.constructor;
    this._mesh = undefined;
  }

  Object.defineProperties(HeightmapTerrainData.prototype, {
    /**
     * An array of credits for this tile.
     * @memberof HeightmapTerrainData.prototype
     * @type {Credit[]}
     */
    credits: {
      get: function () {
        return undefined;
      },
    },
    /**
     * The water mask included in this terrain data, if any.  A water mask is a square
     * Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
     * Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
     * @memberof HeightmapTerrainData.prototype
     * @type {Uint8Array|HTMLImageElement|HTMLCanvasElement}
     */
    waterMask: {
      get: function () {
        return this._waterMask;
      },
    },

    childTileMask: {
      get: function () {
        return this._childTileMask;
      },
    },
  });

  var taskProcessor = new TaskProcessor("createVerticesFromHeightmap");

  /**
   * Creates a {@link TerrainMesh} from this terrain data.
   *
   * @private
   *
   * @param {TilingScheme} tilingScheme The tiling scheme to which this tile belongs.
   * @param {Number} x The X coordinate of the tile for which to create the terrain data.
   * @param {Number} y The Y coordinate of the tile for which to create the terrain data.
   * @param {Number} level The level of the tile for which to create the terrain data.
   * @param {Number} [exaggeration=1.0] The scale used to exaggerate the terrain.
   * @returns {Promise.<TerrainMesh>|undefined} A promise for the terrain mesh, or undefined if too many
   *          asynchronous mesh creations are already in progress and the operation should
   *          be retried later.
   */
  HeightmapTerrainData.prototype.createMesh = function (
    tilingScheme,
    x,
    y,
    level,
    exaggeration
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(tilingScheme)) {
      throw new DeveloperError("tilingScheme is required.");
    }
    if (!defined(x)) {
      throw new DeveloperError("x is required.");
    }
    if (!defined(y)) {
      throw new DeveloperError("y is required.");
    }
    if (!defined(level)) {
      throw new DeveloperError("level is required.");
    }
    //>>includeEnd('debug');

    var ellipsoid = tilingScheme.ellipsoid;
    var nativeRectangle = tilingScheme.tileXYToNativeRectangle(x, y, level);
    var rectangle = tilingScheme.tileXYToRectangle(x, y, level);
    exaggeration = defaultValue(exaggeration, 1.0);

    // Compute the center of the tile for RTC rendering.
    var center = ellipsoid.cartographicToCartesian(Rectangle.center(rectangle));

    var structure = this._structure;

    var levelZeroMaxError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
      ellipsoid,
      this._width,
      tilingScheme.getNumberOfXTilesAtLevel(0)
    );
    var thisLevelMaxError = levelZeroMaxError / (1 << level);
    this._skirtHeight = Math.min(thisLevelMaxError * 4.0, 1000.0);

    var verticesPromise = taskProcessor.scheduleTask({
      heightmap: this._buffer,
      structure: structure,
      includeWebMercatorT: true,
      width: this._width,
      height: this._height,
      nativeRectangle: nativeRectangle,
      rectangle: rectangle,
      relativeToCenter: center,
      ellipsoid: ellipsoid,
      skirtHeight: this._skirtHeight,
      isGeographic: tilingScheme.projection instanceof GeographicProjection,
      exaggeration: exaggeration,
      encoding: this._encoding,
    });

    if (!defined(verticesPromise)) {
      // Postponed
      return undefined;
    }

    var that = this;
    return when(verticesPromise, function (result) {
      var indicesAndEdges;
      if (that._skirtHeight > 0.0) {
        indicesAndEdges = TerrainProvider.getRegularGridAndSkirtIndicesAndEdgeIndices(
          result.gridWidth,
          result.gridHeight
        );
      } else {
        indicesAndEdges = TerrainProvider.getRegularGridIndicesAndEdgeIndices(
          result.gridWidth,
          result.gridHeight
        );
      }

      var vertexCountWithoutSkirts = result.gridWidth * result.gridHeight;

      // Clone complex result objects because the transfer from the web worker
      // has stripped them down to JSON-style objects.
      that._mesh = new TerrainMesh(
        center,
        new Float32Array(result.vertices),
        indicesAndEdges.indices,
        indicesAndEdges.indexCountWithoutSkirts,
        vertexCountWithoutSkirts,
        result.minimumHeight,
        result.maximumHeight,
        BoundingSphere.clone(result.boundingSphere3D),
        Cartesian3.clone(result.occludeePointInScaledSpace),
        result.numberOfAttributes,
        OrientedBoundingBox.clone(result.orientedBoundingBox),
        TerrainEncoding.clone(result.encoding),
        exaggeration,
        indicesAndEdges.westIndicesSouthToNorth,
        indicesAndEdges.southIndicesEastToWest,
        indicesAndEdges.eastIndicesNorthToSouth,
        indicesAndEdges.northIndicesWestToEast
      );

      // Free memory received from server after mesh is created.
      that._buffer = undefined;
      return that._mesh;
    });
  };

  /**
   * @private
   */
  HeightmapTerrainData.prototype._createMeshSync = function (
    tilingScheme,
    x,
    y,
    level,
    exaggeration
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(tilingScheme)) {
      throw new DeveloperError("tilingScheme is required.");
    }
    if (!defined(x)) {
      throw new DeveloperError("x is required.");
    }
    if (!defined(y)) {
      throw new DeveloperError("y is required.");
    }
    if (!defined(level)) {
      throw new DeveloperError("level is required.");
    }
    //>>includeEnd('debug');

    var ellipsoid = tilingScheme.ellipsoid;
    var nativeRectangle = tilingScheme.tileXYToNativeRectangle(x, y, level);
    var rectangle = tilingScheme.tileXYToRectangle(x, y, level);
    exaggeration = defaultValue(exaggeration, 1.0);

    // Compute the center of the tile for RTC rendering.
    var center = ellipsoid.cartographicToCartesian(Rectangle.center(rectangle));

    var structure = this._structure;

    var levelZeroMaxError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
      ellipsoid,
      this._width,
      tilingScheme.getNumberOfXTilesAtLevel(0)
    );
    var thisLevelMaxError = levelZeroMaxError / (1 << level);
    this._skirtHeight = Math.min(thisLevelMaxError * 4.0, 1000.0);

    var result = HeightmapTessellator.computeVertices({
      heightmap: this._buffer,
      structure: structure,
      includeWebMercatorT: true,
      width: this._width,
      height: this._height,
      nativeRectangle: nativeRectangle,
      rectangle: rectangle,
      relativeToCenter: center,
      ellipsoid: ellipsoid,
      skirtHeight: this._skirtHeight,
      isGeographic: tilingScheme.projection instanceof GeographicProjection,
      exaggeration: exaggeration,
    });

    // Free memory received from server after mesh is created.
    this._buffer = undefined;

    var indicesAndEdges;
    if (this._skirtHeight > 0.0) {
      indicesAndEdges = TerrainProvider.getRegularGridAndSkirtIndicesAndEdgeIndices(
        this._width,
        this._height
      );
    } else {
      indicesAndEdges = TerrainProvider.getRegularGridIndicesAndEdgeIndices(
        this._width,
        this._height
      );
    }

    var vertexCountWithoutSkirts = result.gridWidth * result.gridHeight;

    // No need to clone here (as we do in the async version) because the result
    // is not coming from a web worker.
    return new TerrainMesh(
      center,
      result.vertices,
      indicesAndEdges.indices,
      indicesAndEdges.indexCountWithoutSkirts,
      vertexCountWithoutSkirts,
      result.minimumHeight,
      result.maximumHeight,
      result.boundingSphere3D,
      result.occludeePointInScaledSpace,
      result.encoding.getStride(),
      result.orientedBoundingBox,
      result.encoding,
      exaggeration,
      indicesAndEdges.westIndicesSouthToNorth,
      indicesAndEdges.southIndicesEastToWest,
      indicesAndEdges.eastIndicesNorthToSouth,
      indicesAndEdges.northIndicesWestToEast
    );
  };

  /**
   * Computes the terrain height at a specified longitude and latitude.
   *
   * @param {Rectangle} rectangle The rectangle covered by this terrain data.
   * @param {Number} longitude The longitude in radians.
   * @param {Number} latitude The latitude in radians.
   * @returns {Number} The terrain height at the specified position.  If the position
   *          is outside the rectangle, this method will extrapolate the height, which is likely to be wildly
   *          incorrect for positions far outside the rectangle.
   */
  HeightmapTerrainData.prototype.interpolateHeight = function (
    rectangle,
    longitude,
    latitude
  ) {
    var width = this._width;
    var height = this._height;

    var structure = this._structure;
    var stride = structure.stride;
    var elementsPerHeight = structure.elementsPerHeight;
    var elementMultiplier = structure.elementMultiplier;
    var isBigEndian = structure.isBigEndian;
    var heightOffset = structure.heightOffset;
    var heightScale = structure.heightScale;

    var heightSample;
    if (defined(this._mesh)) {
      var buffer = this._mesh.vertices;
      var encoding = this._mesh.encoding;
      var exaggeration = this._mesh.exaggeration;
      heightSample = interpolateMeshHeight(
        buffer,
        encoding,
        heightOffset,
        heightScale,
        rectangle,
        width,
        height,
        longitude,
        latitude,
        exaggeration
      );
    } else {
      heightSample = interpolateHeight(
        this._buffer,
        elementsPerHeight,
        elementMultiplier,
        stride,
        isBigEndian,
        rectangle,
        width,
        height,
        longitude,
        latitude
      );
      heightSample = heightSample * heightScale + heightOffset;
    }

    return heightSample;
  };

  /**
   * Upsamples this terrain data for use by a descendant tile.  The resulting instance will contain a subset of the
   * height samples in this instance, interpolated if necessary.
   *
   * @param {TilingScheme} tilingScheme The tiling scheme of this terrain data.
   * @param {Number} thisX The X coordinate of this tile in the tiling scheme.
   * @param {Number} thisY The Y coordinate of this tile in the tiling scheme.
   * @param {Number} thisLevel The level of this tile in the tiling scheme.
   * @param {Number} descendantX The X coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantY The Y coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantLevel The level within the tiling scheme of the descendant tile for which we are upsampling.
   * @returns {Promise.<HeightmapTerrainData>|undefined} A promise for upsampled heightmap terrain data for the descendant tile,
   *          or undefined if too many asynchronous upsample operations are in progress and the request has been
   *          deferred.
   */
  HeightmapTerrainData.prototype.upsample = function (
    tilingScheme,
    thisX,
    thisY,
    thisLevel,
    descendantX,
    descendantY,
    descendantLevel
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(tilingScheme)) {
      throw new DeveloperError("tilingScheme is required.");
    }
    if (!defined(thisX)) {
      throw new DeveloperError("thisX is required.");
    }
    if (!defined(thisY)) {
      throw new DeveloperError("thisY is required.");
    }
    if (!defined(thisLevel)) {
      throw new DeveloperError("thisLevel is required.");
    }
    if (!defined(descendantX)) {
      throw new DeveloperError("descendantX is required.");
    }
    if (!defined(descendantY)) {
      throw new DeveloperError("descendantY is required.");
    }
    if (!defined(descendantLevel)) {
      throw new DeveloperError("descendantLevel is required.");
    }
    var levelDifference = descendantLevel - thisLevel;
    if (levelDifference > 1) {
      throw new DeveloperError(
        "Upsampling through more than one level at a time is not currently supported."
      );
    }
    //>>includeEnd('debug');

    var meshData = this._mesh;
    if (!defined(meshData)) {
      return undefined;
    }

    var width = this._width;
    var height = this._height;
    var structure = this._structure;
    var stride = structure.stride;

    var heights = new this._bufferType(width * height * stride);

    var buffer = meshData.vertices;
    var encoding = meshData.encoding;

    // PERFORMANCE_IDEA: don't recompute these rectangles - the caller already knows them.
    var sourceRectangle = tilingScheme.tileXYToRectangle(thisX, thisY, thisLevel);
    var destinationRectangle = tilingScheme.tileXYToRectangle(
      descendantX,
      descendantY,
      descendantLevel
    );

    var heightOffset = structure.heightOffset;
    var heightScale = structure.heightScale;
    var exaggeration = meshData.exaggeration;

    var elementsPerHeight = structure.elementsPerHeight;
    var elementMultiplier = structure.elementMultiplier;
    var isBigEndian = structure.isBigEndian;

    var divisor = Math.pow(elementMultiplier, elementsPerHeight - 1);

    for (var j = 0; j < height; ++j) {
      var latitude = CesiumMath.lerp(
        destinationRectangle.north,
        destinationRectangle.south,
        j / (height - 1)
      );
      for (var i = 0; i < width; ++i) {
        var longitude = CesiumMath.lerp(
          destinationRectangle.west,
          destinationRectangle.east,
          i / (width - 1)
        );
        var heightSample = interpolateMeshHeight(
          buffer,
          encoding,
          heightOffset,
          heightScale,
          sourceRectangle,
          width,
          height,
          longitude,
          latitude,
          exaggeration
        );

        // Use conditionals here instead of Math.min and Math.max so that an undefined
        // lowestEncodedHeight or highestEncodedHeight has no effect.
        heightSample =
          heightSample < structure.lowestEncodedHeight
            ? structure.lowestEncodedHeight
            : heightSample;
        heightSample =
          heightSample > structure.highestEncodedHeight
            ? structure.highestEncodedHeight
            : heightSample;

        setHeight(
          heights,
          elementsPerHeight,
          elementMultiplier,
          divisor,
          stride,
          isBigEndian,
          j * width + i,
          heightSample
        );
      }
    }

    return new HeightmapTerrainData({
      buffer: heights,
      width: width,
      height: height,
      childTileMask: 0,
      structure: this._structure,
      createdByUpsampling: true,
    });
  };

  /**
   * Determines if a given child tile is available, based on the
   * {@link HeightmapTerrainData.childTileMask}.  The given child tile coordinates are assumed
   * to be one of the four children of this tile.  If non-child tile coordinates are
   * given, the availability of the southeast child tile is returned.
   *
   * @param {Number} thisX The tile X coordinate of this (the parent) tile.
   * @param {Number} thisY The tile Y coordinate of this (the parent) tile.
   * @param {Number} childX The tile X coordinate of the child tile to check for availability.
   * @param {Number} childY The tile Y coordinate of the child tile to check for availability.
   * @returns {Boolean} True if the child tile is available; otherwise, false.
   */
  HeightmapTerrainData.prototype.isChildAvailable = function (
    thisX,
    thisY,
    childX,
    childY
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(thisX)) {
      throw new DeveloperError("thisX is required.");
    }
    if (!defined(thisY)) {
      throw new DeveloperError("thisY is required.");
    }
    if (!defined(childX)) {
      throw new DeveloperError("childX is required.");
    }
    if (!defined(childY)) {
      throw new DeveloperError("childY is required.");
    }
    //>>includeEnd('debug');

    var bitNumber = 2; // northwest child
    if (childX !== thisX * 2) {
      ++bitNumber; // east child
    }
    if (childY !== thisY * 2) {
      bitNumber -= 2; // south child
    }

    return (this._childTileMask & (1 << bitNumber)) !== 0;
  };

  /**
   * Gets a value indicating whether or not this terrain data was created by upsampling lower resolution
   * terrain data.  If this value is false, the data was obtained from some other source, such
   * as by downloading it from a remote server.  This method should return true for instances
   * returned from a call to {@link HeightmapTerrainData#upsample}.
   *
   * @returns {Boolean} True if this instance was created by upsampling; otherwise, false.
   */
  HeightmapTerrainData.prototype.wasCreatedByUpsampling = function () {
    return this._createdByUpsampling;
  };

  function interpolateHeight(
    sourceHeights,
    elementsPerHeight,
    elementMultiplier,
    stride,
    isBigEndian,
    sourceRectangle,
    width,
    height,
    longitude,
    latitude
  ) {
    var fromWest =
      ((longitude - sourceRectangle.west) * (width - 1)) /
      (sourceRectangle.east - sourceRectangle.west);
    var fromSouth =
      ((latitude - sourceRectangle.south) * (height - 1)) /
      (sourceRectangle.north - sourceRectangle.south);

    var westInteger = fromWest | 0;
    var eastInteger = westInteger + 1;
    if (eastInteger >= width) {
      eastInteger = width - 1;
      westInteger = width - 2;
    }

    var southInteger = fromSouth | 0;
    var northInteger = southInteger + 1;
    if (northInteger >= height) {
      northInteger = height - 1;
      southInteger = height - 2;
    }

    var dx = fromWest - westInteger;
    var dy = fromSouth - southInteger;

    southInteger = height - 1 - southInteger;
    northInteger = height - 1 - northInteger;

    var southwestHeight = getHeight(
      sourceHeights,
      elementsPerHeight,
      elementMultiplier,
      stride,
      isBigEndian,
      southInteger * width + westInteger
    );
    var southeastHeight = getHeight(
      sourceHeights,
      elementsPerHeight,
      elementMultiplier,
      stride,
      isBigEndian,
      southInteger * width + eastInteger
    );
    var northwestHeight = getHeight(
      sourceHeights,
      elementsPerHeight,
      elementMultiplier,
      stride,
      isBigEndian,
      northInteger * width + westInteger
    );
    var northeastHeight = getHeight(
      sourceHeights,
      elementsPerHeight,
      elementMultiplier,
      stride,
      isBigEndian,
      northInteger * width + eastInteger
    );

    return triangleInterpolateHeight(
      dx,
      dy,
      southwestHeight,
      southeastHeight,
      northwestHeight,
      northeastHeight
    );
  }

  function interpolateMeshHeight(
    buffer,
    encoding,
    heightOffset,
    heightScale,
    sourceRectangle,
    width,
    height,
    longitude,
    latitude,
    exaggeration
  ) {
    // returns a height encoded according to the structure's heightScale and heightOffset.
    var fromWest =
      ((longitude - sourceRectangle.west) * (width - 1)) /
      (sourceRectangle.east - sourceRectangle.west);
    var fromSouth =
      ((latitude - sourceRectangle.south) * (height - 1)) /
      (sourceRectangle.north - sourceRectangle.south);

    var westInteger = fromWest | 0;
    var eastInteger = westInteger + 1;
    if (eastInteger >= width) {
      eastInteger = width - 1;
      westInteger = width - 2;
    }

    var southInteger = fromSouth | 0;
    var northInteger = southInteger + 1;
    if (northInteger >= height) {
      northInteger = height - 1;
      southInteger = height - 2;
    }

    var dx = fromWest - westInteger;
    var dy = fromSouth - southInteger;

    southInteger = height - 1 - southInteger;
    northInteger = height - 1 - northInteger;

    var southwestHeight =
      (encoding.decodeHeight(buffer, southInteger * width + westInteger) /
        exaggeration -
        heightOffset) /
      heightScale;
    var southeastHeight =
      (encoding.decodeHeight(buffer, southInteger * width + eastInteger) /
        exaggeration -
        heightOffset) /
      heightScale;
    var northwestHeight =
      (encoding.decodeHeight(buffer, northInteger * width + westInteger) /
        exaggeration -
        heightOffset) /
      heightScale;
    var northeastHeight =
      (encoding.decodeHeight(buffer, northInteger * width + eastInteger) /
        exaggeration -
        heightOffset) /
      heightScale;

    return triangleInterpolateHeight(
      dx,
      dy,
      southwestHeight,
      southeastHeight,
      northwestHeight,
      northeastHeight
    );
  }

  function triangleInterpolateHeight(
    dX,
    dY,
    southwestHeight,
    southeastHeight,
    northwestHeight,
    northeastHeight
  ) {
    // The HeightmapTessellator bisects the quad from southwest to northeast.
    if (dY < dX) {
      // Lower right triangle
      return (
        southwestHeight +
        dX * (southeastHeight - southwestHeight) +
        dY * (northeastHeight - southeastHeight)
      );
    }

    // Upper left triangle
    return (
      southwestHeight +
      dX * (northeastHeight - northwestHeight) +
      dY * (northwestHeight - southwestHeight)
    );
  }

  function getHeight(
    heights,
    elementsPerHeight,
    elementMultiplier,
    stride,
    isBigEndian,
    index
  ) {
    index *= stride;

    var height = 0;
    var i;

    if (isBigEndian) {
      for (i = 0; i < elementsPerHeight; ++i) {
        height = height * elementMultiplier + heights[index + i];
      }
    } else {
      for (i = elementsPerHeight - 1; i >= 0; --i) {
        height = height * elementMultiplier + heights[index + i];
      }
    }

    return height;
  }

  function setHeight(
    heights,
    elementsPerHeight,
    elementMultiplier,
    divisor,
    stride,
    isBigEndian,
    index,
    height
  ) {
    index *= stride;

    var i;
    if (isBigEndian) {
      for (i = 0; i < elementsPerHeight - 1; ++i) {
        heights[index + i] = (height / divisor) | 0;
        height -= heights[index + i] * divisor;
        divisor /= elementMultiplier;
      }
    } else {
      for (i = elementsPerHeight - 1; i > 0; --i) {
        heights[index + i] = (height / divisor) | 0;
        height -= heights[index + i] * divisor;
        divisor /= elementMultiplier;
      }
    }
    heights[index + i] = height;
  }

  /**
   * Reports the availability of tiles in a {@link TilingScheme}.
   *
   * @alias TileAvailability
   * @constructor
   *
   * @param {TilingScheme} tilingScheme The tiling scheme in which to report availability.
   * @param {Number} maximumLevel The maximum tile level that is potentially available.
   */
  function TileAvailability(tilingScheme, maximumLevel) {
    this._tilingScheme = tilingScheme;
    this._maximumLevel = maximumLevel;

    this._rootNodes = [];
  }

  var rectangleScratch = new Rectangle();

  function findNode(level, x, y, nodes) {
    var count = nodes.length;
    for (var i = 0; i < count; ++i) {
      var node = nodes[i];
      if (node.x === x && node.y === y && node.level === level) {
        return true;
      }
    }

    return false;
  }

  /**
   * Marks a rectangular range of tiles in a particular level as being available.  For best performance,
   * add your ranges in order of increasing level.
   *
   * @param {Number} level The level.
   * @param {Number} startX The X coordinate of the first available tiles at the level.
   * @param {Number} startY The Y coordinate of the first available tiles at the level.
   * @param {Number} endX The X coordinate of the last available tiles at the level.
   * @param {Number} endY The Y coordinate of the last available tiles at the level.
   */
  TileAvailability.prototype.addAvailableTileRange = function (
    level,
    startX,
    startY,
    endX,
    endY
  ) {
    var tilingScheme = this._tilingScheme;

    var rootNodes = this._rootNodes;
    if (level === 0) {
      for (var y = startY; y <= endY; ++y) {
        for (var x = startX; x <= endX; ++x) {
          if (!findNode(level, x, y, rootNodes)) {
            rootNodes.push(new QuadtreeNode(tilingScheme, undefined, 0, x, y));
          }
        }
      }
    }

    tilingScheme.tileXYToRectangle(startX, startY, level, rectangleScratch);
    var west = rectangleScratch.west;
    var north = rectangleScratch.north;

    tilingScheme.tileXYToRectangle(endX, endY, level, rectangleScratch);
    var east = rectangleScratch.east;
    var south = rectangleScratch.south;

    var rectangleWithLevel = new RectangleWithLevel(
      level,
      west,
      south,
      east,
      north
    );

    for (var i = 0; i < rootNodes.length; ++i) {
      var rootNode = rootNodes[i];
      if (rectanglesOverlap(rootNode.extent, rectangleWithLevel)) {
        putRectangleInQuadtree(this._maximumLevel, rootNode, rectangleWithLevel);
      }
    }
  };

  /**
   * Determines the level of the most detailed tile covering the position.  This function
   * usually completes in time logarithmic to the number of rectangles added with
   * {@link TileAvailability#addAvailableTileRange}.
   *
   * @param {Cartographic} position The position for which to determine the maximum available level.  The height component is ignored.
   * @return {Number} The level of the most detailed tile covering the position.
   * @throws {DeveloperError} If position is outside any tile according to the tiling scheme.
   */
  TileAvailability.prototype.computeMaximumLevelAtPosition = function (position) {
    // Find the root node that contains this position.
    var node;
    for (var nodeIndex = 0; nodeIndex < this._rootNodes.length; ++nodeIndex) {
      var rootNode = this._rootNodes[nodeIndex];
      if (rectangleContainsPosition(rootNode.extent, position)) {
        node = rootNode;
        break;
      }
    }

    if (!defined(node)) {
      return -1;
    }

    return findMaxLevelFromNode(undefined, node, position);
  };

  var rectanglesScratch = [];
  var remainingToCoverByLevelScratch = [];
  var westScratch = new Rectangle();
  var eastScratch = new Rectangle();

  /**
   * Finds the most detailed level that is available _everywhere_ within a given rectangle.  More detailed
   * tiles may be available in parts of the rectangle, but not the whole thing.  The return value of this
   * function may be safely passed to {@link sampleTerrain} for any position within the rectangle.  This function
   * usually completes in time logarithmic to the number of rectangles added with
   * {@link TileAvailability#addAvailableTileRange}.
   *
   * @param {Rectangle} rectangle The rectangle.
   * @return {Number} The best available level for the entire rectangle.
   */
  TileAvailability.prototype.computeBestAvailableLevelOverRectangle = function (
    rectangle
  ) {
    var rectangles = rectanglesScratch;
    rectangles.length = 0;

    if (rectangle.east < rectangle.west) {
      // Rectangle crosses the IDL, make it two rectangles.
      rectangles.push(
        Rectangle.fromRadians(
          -Math.PI,
          rectangle.south,
          rectangle.east,
          rectangle.north,
          westScratch
        )
      );
      rectangles.push(
        Rectangle.fromRadians(
          rectangle.west,
          rectangle.south,
          Math.PI,
          rectangle.north,
          eastScratch
        )
      );
    } else {
      rectangles.push(rectangle);
    }

    var remainingToCoverByLevel = remainingToCoverByLevelScratch;
    remainingToCoverByLevel.length = 0;

    var i;
    for (i = 0; i < this._rootNodes.length; ++i) {
      updateCoverageWithNode(
        remainingToCoverByLevel,
        this._rootNodes[i],
        rectangles
      );
    }

    for (i = remainingToCoverByLevel.length - 1; i >= 0; --i) {
      if (
        defined(remainingToCoverByLevel[i]) &&
        remainingToCoverByLevel[i].length === 0
      ) {
        return i;
      }
    }

    return 0;
  };

  var cartographicScratch = new Cartographic();

  /**
   * Determines if a particular tile is available.
   * @param {Number} level The tile level to check.
   * @param {Number} x The X coordinate of the tile to check.
   * @param {Number} y The Y coordinate of the tile to check.
   * @return {Boolean} True if the tile is available; otherwise, false.
   */
  TileAvailability.prototype.isTileAvailable = function (level, x, y) {
    // Get the center of the tile and find the maximum level at that position.
    // Because availability is by tile, if the level is available at that point, it
    // is sure to be available for the whole tile.  We assume that if a tile at level n exists,
    // then all its parent tiles back to level 0 exist too.  This isn't really enforced
    // anywhere, but Cesium would never load a tile for which this is not true.
    var rectangle = this._tilingScheme.tileXYToRectangle(
      x,
      y,
      level,
      rectangleScratch
    );
    Rectangle.center(rectangle, cartographicScratch);
    return this.computeMaximumLevelAtPosition(cartographicScratch) >= level;
  };

  /**
   * Computes a bit mask indicating which of a tile's four children exist.
   * If a child's bit is set, a tile is available for that child.  If it is cleared,
   * the tile is not available.  The bit values are as follows:
   * <table>
   *     <tr><th>Bit Position</th><th>Bit Value</th><th>Child Tile</th></tr>
   *     <tr><td>0</td><td>1</td><td>Southwest</td></tr>
   *     <tr><td>1</td><td>2</td><td>Southeast</td></tr>
   *     <tr><td>2</td><td>4</td><td>Northwest</td></tr>
   *     <tr><td>3</td><td>8</td><td>Northeast</td></tr>
   * </table>
   *
   * @param {Number} level The level of the parent tile.
   * @param {Number} x The X coordinate of the parent tile.
   * @param {Number} y The Y coordinate of the parent tile.
   * @return {Number} The bit mask indicating child availability.
   */
  TileAvailability.prototype.computeChildMaskForTile = function (level, x, y) {
    var childLevel = level + 1;
    if (childLevel >= this._maximumLevel) {
      return 0;
    }

    var mask = 0;

    mask |= this.isTileAvailable(childLevel, 2 * x, 2 * y + 1) ? 1 : 0;
    mask |= this.isTileAvailable(childLevel, 2 * x + 1, 2 * y + 1) ? 2 : 0;
    mask |= this.isTileAvailable(childLevel, 2 * x, 2 * y) ? 4 : 0;
    mask |= this.isTileAvailable(childLevel, 2 * x + 1, 2 * y) ? 8 : 0;

    return mask;
  };

  function QuadtreeNode(tilingScheme, parent, level, x, y) {
    this.tilingScheme = tilingScheme;
    this.parent = parent;
    this.level = level;
    this.x = x;
    this.y = y;
    this.extent = tilingScheme.tileXYToRectangle(x, y, level);

    this.rectangles = [];
    this._sw = undefined;
    this._se = undefined;
    this._nw = undefined;
    this._ne = undefined;
  }

  Object.defineProperties(QuadtreeNode.prototype, {
    nw: {
      get: function () {
        if (!this._nw) {
          this._nw = new QuadtreeNode(
            this.tilingScheme,
            this,
            this.level + 1,
            this.x * 2,
            this.y * 2
          );
        }
        return this._nw;
      },
    },

    ne: {
      get: function () {
        if (!this._ne) {
          this._ne = new QuadtreeNode(
            this.tilingScheme,
            this,
            this.level + 1,
            this.x * 2 + 1,
            this.y * 2
          );
        }
        return this._ne;
      },
    },

    sw: {
      get: function () {
        if (!this._sw) {
          this._sw = new QuadtreeNode(
            this.tilingScheme,
            this,
            this.level + 1,
            this.x * 2,
            this.y * 2 + 1
          );
        }
        return this._sw;
      },
    },

    se: {
      get: function () {
        if (!this._se) {
          this._se = new QuadtreeNode(
            this.tilingScheme,
            this,
            this.level + 1,
            this.x * 2 + 1,
            this.y * 2 + 1
          );
        }
        return this._se;
      },
    },
  });

  function RectangleWithLevel(level, west, south, east, north) {
    this.level = level;
    this.west = west;
    this.south = south;
    this.east = east;
    this.north = north;
  }

  function rectanglesOverlap(rectangle1, rectangle2) {
    var west = Math.max(rectangle1.west, rectangle2.west);
    var south = Math.max(rectangle1.south, rectangle2.south);
    var east = Math.min(rectangle1.east, rectangle2.east);
    var north = Math.min(rectangle1.north, rectangle2.north);
    return south < north && west < east;
  }

  function putRectangleInQuadtree(maxDepth, node, rectangle) {
    while (node.level < maxDepth) {
      if (rectangleFullyContainsRectangle(node.nw.extent, rectangle)) {
        node = node.nw;
      } else if (rectangleFullyContainsRectangle(node.ne.extent, rectangle)) {
        node = node.ne;
      } else if (rectangleFullyContainsRectangle(node.sw.extent, rectangle)) {
        node = node.sw;
      } else if (rectangleFullyContainsRectangle(node.se.extent, rectangle)) {
        node = node.se;
      } else {
        break;
      }
    }

    if (
      node.rectangles.length === 0 ||
      node.rectangles[node.rectangles.length - 1].level <= rectangle.level
    ) {
      node.rectangles.push(rectangle);
    } else {
      // Maintain ordering by level when inserting.
      var index = binarySearch(
        node.rectangles,
        rectangle.level,
        rectangleLevelComparator
      );
      if (index <= 0) {
        index = ~index;
      }
      node.rectangles.splice(index, 0, rectangle);
    }
  }

  function rectangleLevelComparator(a, b) {
    return a.level - b;
  }

  function rectangleFullyContainsRectangle(potentialContainer, rectangleToTest) {
    return (
      rectangleToTest.west >= potentialContainer.west &&
      rectangleToTest.east <= potentialContainer.east &&
      rectangleToTest.south >= potentialContainer.south &&
      rectangleToTest.north <= potentialContainer.north
    );
  }

  function rectangleContainsPosition(potentialContainer, positionToTest) {
    return (
      positionToTest.longitude >= potentialContainer.west &&
      positionToTest.longitude <= potentialContainer.east &&
      positionToTest.latitude >= potentialContainer.south &&
      positionToTest.latitude <= potentialContainer.north
    );
  }

  function findMaxLevelFromNode(stopNode, node, position) {
    var maxLevel = 0;

    // Find the deepest quadtree node containing this point.
    var found = false;
    while (!found) {
      var nw = node._nw && rectangleContainsPosition(node._nw.extent, position);
      var ne = node._ne && rectangleContainsPosition(node._ne.extent, position);
      var sw = node._sw && rectangleContainsPosition(node._sw.extent, position);
      var se = node._se && rectangleContainsPosition(node._se.extent, position);

      // The common scenario is that the point is in only one quadrant and we can simply
      // iterate down the tree.  But if the point is on a boundary between tiles, it is
      // in multiple tiles and we need to check all of them, so use recursion.
      if (nw + ne + sw + se > 1) {
        if (nw) {
          maxLevel = Math.max(
            maxLevel,
            findMaxLevelFromNode(node, node._nw, position)
          );
        }
        if (ne) {
          maxLevel = Math.max(
            maxLevel,
            findMaxLevelFromNode(node, node._ne, position)
          );
        }
        if (sw) {
          maxLevel = Math.max(
            maxLevel,
            findMaxLevelFromNode(node, node._sw, position)
          );
        }
        if (se) {
          maxLevel = Math.max(
            maxLevel,
            findMaxLevelFromNode(node, node._se, position)
          );
        }
        break;
      } else if (nw) {
        node = node._nw;
      } else if (ne) {
        node = node._ne;
      } else if (sw) {
        node = node._sw;
      } else if (se) {
        node = node._se;
      } else {
        found = true;
      }
    }

    // Work up the tree until we find a rectangle that contains this point.
    while (node !== stopNode) {
      var rectangles = node.rectangles;

      // Rectangles are sorted by level, lowest first.
      for (
        var i = rectangles.length - 1;
        i >= 0 && rectangles[i].level > maxLevel;
        --i
      ) {
        var rectangle = rectangles[i];
        if (rectangleContainsPosition(rectangle, position)) {
          maxLevel = rectangle.level;
        }
      }

      node = node.parent;
    }

    return maxLevel;
  }

  function updateCoverageWithNode(
    remainingToCoverByLevel,
    node,
    rectanglesToCover
  ) {
    if (!node) {
      return;
    }

    var i;
    var anyOverlap = false;
    for (i = 0; i < rectanglesToCover.length; ++i) {
      anyOverlap =
        anyOverlap || rectanglesOverlap(node.extent, rectanglesToCover[i]);
    }

    if (!anyOverlap) {
      // This node is not applicable to the rectangle(s).
      return;
    }

    var rectangles = node.rectangles;
    for (i = 0; i < rectangles.length; ++i) {
      var rectangle = rectangles[i];

      if (!remainingToCoverByLevel[rectangle.level]) {
        remainingToCoverByLevel[rectangle.level] = rectanglesToCover;
      }

      remainingToCoverByLevel[rectangle.level] = subtractRectangle(
        remainingToCoverByLevel[rectangle.level],
        rectangle
      );
    }

    // Update with child nodes.
    updateCoverageWithNode(remainingToCoverByLevel, node._nw, rectanglesToCover);
    updateCoverageWithNode(remainingToCoverByLevel, node._ne, rectanglesToCover);
    updateCoverageWithNode(remainingToCoverByLevel, node._sw, rectanglesToCover);
    updateCoverageWithNode(remainingToCoverByLevel, node._se, rectanglesToCover);
  }

  function subtractRectangle(rectangleList, rectangleToSubtract) {
    var result = [];
    for (var i = 0; i < rectangleList.length; ++i) {
      var rectangle = rectangleList[i];
      if (!rectanglesOverlap(rectangle, rectangleToSubtract)) {
        // Disjoint rectangles.  Original rectangle is unmodified.
        result.push(rectangle);
      } else {
        // rectangleToSubtract partially or completely overlaps rectangle.
        if (rectangle.west < rectangleToSubtract.west) {
          result.push(
            new Rectangle(
              rectangle.west,
              rectangle.south,
              rectangleToSubtract.west,
              rectangle.north
            )
          );
        }
        if (rectangle.east > rectangleToSubtract.east) {
          result.push(
            new Rectangle(
              rectangleToSubtract.east,
              rectangle.south,
              rectangle.east,
              rectangle.north
            )
          );
        }
        if (rectangle.south < rectangleToSubtract.south) {
          result.push(
            new Rectangle(
              Math.max(rectangleToSubtract.west, rectangle.west),
              rectangle.south,
              Math.min(rectangleToSubtract.east, rectangle.east),
              rectangleToSubtract.south
            )
          );
        }
        if (rectangle.north > rectangleToSubtract.north) {
          result.push(
            new Rectangle(
              Math.max(rectangleToSubtract.west, rectangle.west),
              rectangleToSubtract.north,
              Math.min(rectangleToSubtract.east, rectangle.east),
              rectangle.north
            )
          );
        }
      }
    }

    return result;
  }

  /**
   * Formats an error object into a String.  If available, uses name, message, and stack
   * properties, otherwise, falls back on toString().
   *
   * @function
   *
   * @param {*} object The item to find in the array.
   * @returns {String} A string containing the formatted error.
   */
  function formatError(object) {
    var result;

    var name = object.name;
    var message = object.message;
    if (defined(name) && defined(message)) {
      result = name + ": " + message;
    } else {
      result = object.toString();
    }

    var stack = object.stack;
    if (defined(stack)) {
      result += "\n" + stack;
    }

    return result;
  }

  /**
   * Provides details about an error that occurred in an {@link ImageryProvider} or a {@link TerrainProvider}.
   *
   * @alias TileProviderError
   * @constructor
   *
   * @param {ImageryProvider|TerrainProvider} provider The imagery or terrain provider that experienced the error.
   * @param {String} message A message describing the error.
   * @param {Number} [x] The X coordinate of the tile that experienced the error, or undefined if the error
   *        is not specific to a particular tile.
   * @param {Number} [y] The Y coordinate of the tile that experienced the error, or undefined if the error
   *        is not specific to a particular tile.
   * @param {Number} [level] The level of the tile that experienced the error, or undefined if the error
   *        is not specific to a particular tile.
   * @param {Number} [timesRetried=0] The number of times this operation has been retried.
   * @param {Error} [error] The error or exception that occurred, if any.
   */
  function TileProviderError(
    provider,
    message,
    x,
    y,
    level,
    timesRetried,
    error
  ) {
    /**
     * The {@link ImageryProvider} or {@link TerrainProvider} that experienced the error.
     * @type {ImageryProvider|TerrainProvider}
     */
    this.provider = provider;

    /**
     * The message describing the error.
     * @type {String}
     */
    this.message = message;

    /**
     * The X coordinate of the tile that experienced the error.  If the error is not specific
     * to a particular tile, this property will be undefined.
     * @type {Number}
     */
    this.x = x;

    /**
     * The Y coordinate of the tile that experienced the error.  If the error is not specific
     * to a particular tile, this property will be undefined.
     * @type {Number}
     */
    this.y = y;

    /**
     * The level-of-detail of the tile that experienced the error.  If the error is not specific
     * to a particular tile, this property will be undefined.
     * @type {Number}
     */
    this.level = level;

    /**
     * The number of times this operation has been retried.
     * @type {Number}
     * @default 0
     */
    this.timesRetried = defaultValue(timesRetried, 0);

    /**
     * True if the failed operation should be retried; otherwise, false.  The imagery or terrain provider
     * will set the initial value of this property before raising the event, but any listeners
     * can change it.  The value after the last listener is invoked will be acted upon.
     * @type {Boolean}
     * @default false
     */
    this.retry = false;

    /**
     * The error or exception that occurred, if any.
     * @type {Error}
     */
    this.error = error;
  }

  /**
   * Handles an error in an {@link ImageryProvider} or {@link TerrainProvider} by raising an event if it has any listeners, or by
   * logging the error to the console if the event has no listeners.  This method also tracks the number
   * of times the operation has been retried and will automatically retry if requested to do so by the
   * event listeners.
   *
   * @param {TileProviderError} previousError The error instance returned by this function the last
   *        time it was called for this error, or undefined if this is the first time this error has
   *        occurred.
   * @param {ImageryProvider|TerrainProvider} provider The imagery or terrain provider that encountered the error.
   * @param {Event} event The event to raise to inform listeners of the error.
   * @param {String} message The message describing the error.
   * @param {Number} x The X coordinate of the tile that experienced the error, or undefined if the
   *        error is not specific to a particular tile.
   * @param {Number} y The Y coordinate of the tile that experienced the error, or undefined if the
   *        error is not specific to a particular tile.
   * @param {Number} level The level-of-detail of the tile that experienced the error, or undefined if the
   *        error is not specific to a particular tile.
   * @param {TileProviderError.RetryFunction} retryFunction The function to call to retry the operation.  If undefined, the
   *        operation will not be retried.
   * @param {Error} [errorDetails] The error or exception that occurred, if any.
   * @returns {TileProviderError} The error instance that was passed to the event listeners and that
   *          should be passed to this function the next time it is called for the same error in order
   *          to track retry counts.
   */
  TileProviderError.handleError = function (
    previousError,
    provider,
    event,
    message,
    x,
    y,
    level,
    retryFunction,
    errorDetails
  ) {
    var error = previousError;
    if (!defined(previousError)) {
      error = new TileProviderError(
        provider,
        message,
        x,
        y,
        level,
        0,
        errorDetails
      );
    } else {
      error.provider = provider;
      error.message = message;
      error.x = x;
      error.y = y;
      error.level = level;
      error.retry = false;
      error.error = errorDetails;
      ++error.timesRetried;
    }

    if (event.numberOfListeners > 0) {
      event.raiseEvent(error);
    } else {
      console.log(
        'An error occurred in "' +
          provider.constructor.name +
          '": ' +
          formatError(message)
      );
    }

    if (error.retry && defined(retryFunction)) {
      retryFunction();
    }

    return error;
  };

  /**
   * Handles success of an operation by resetting the retry count of a previous error, if any.  This way,
   * if the error occurs again in the future, the listeners will be informed that it has not yet been retried.
   *
   * @param {TileProviderError} previousError The previous error, or undefined if this operation has
   *        not previously resulted in an error.
   */
  TileProviderError.handleSuccess = function (previousError) {
    if (defined(previousError)) {
      previousError.timesRetried = -1;
    }
  };

  /**
   * A tiling scheme for geometry referenced to a {@link WebMercatorProjection}, EPSG:3857.  This is
   * the tiling scheme used by Google Maps, Microsoft Bing Maps, and most of ESRI ArcGIS Online.
   *
   * @alias WebMercatorTilingScheme
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid whose surface is being tiled. Defaults to
   * the WGS84 ellipsoid.
   * @param {Number} [options.numberOfLevelZeroTilesX=1] The number of tiles in the X direction at level zero of
   *        the tile tree.
   * @param {Number} [options.numberOfLevelZeroTilesY=1] The number of tiles in the Y direction at level zero of
   *        the tile tree.
   * @param {Cartesian2} [options.rectangleSouthwestInMeters] The southwest corner of the rectangle covered by the
   *        tiling scheme, in meters.  If this parameter or rectangleNortheastInMeters is not specified, the entire
   *        globe is covered in the longitude direction and an equal distance is covered in the latitude
   *        direction, resulting in a square projection.
   * @param {Cartesian2} [options.rectangleNortheastInMeters] The northeast corner of the rectangle covered by the
   *        tiling scheme, in meters.  If this parameter or rectangleSouthwestInMeters is not specified, the entire
   *        globe is covered in the longitude direction and an equal distance is covered in the latitude
   *        direction, resulting in a square projection.
   */
  function WebMercatorTilingScheme(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    this._numberOfLevelZeroTilesX = defaultValue(
      options.numberOfLevelZeroTilesX,
      1
    );
    this._numberOfLevelZeroTilesY = defaultValue(
      options.numberOfLevelZeroTilesY,
      1
    );

    this._projection = new WebMercatorProjection(this._ellipsoid);

    if (
      defined(options.rectangleSouthwestInMeters) &&
      defined(options.rectangleNortheastInMeters)
    ) {
      this._rectangleSouthwestInMeters = options.rectangleSouthwestInMeters;
      this._rectangleNortheastInMeters = options.rectangleNortheastInMeters;
    } else {
      var semimajorAxisTimesPi = this._ellipsoid.maximumRadius * Math.PI;
      this._rectangleSouthwestInMeters = new Cartesian2(
        -semimajorAxisTimesPi,
        -semimajorAxisTimesPi
      );
      this._rectangleNortheastInMeters = new Cartesian2(
        semimajorAxisTimesPi,
        semimajorAxisTimesPi
      );
    }

    var southwest = this._projection.unproject(this._rectangleSouthwestInMeters);
    var northeast = this._projection.unproject(this._rectangleNortheastInMeters);
    this._rectangle = new Rectangle(
      southwest.longitude,
      southwest.latitude,
      northeast.longitude,
      northeast.latitude
    );
  }

  Object.defineProperties(WebMercatorTilingScheme.prototype, {
    /**
     * Gets the ellipsoid that is tiled by this tiling scheme.
     * @memberof WebMercatorTilingScheme.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },

    /**
     * Gets the rectangle, in radians, covered by this tiling scheme.
     * @memberof WebMercatorTilingScheme.prototype
     * @type {Rectangle}
     */
    rectangle: {
      get: function () {
        return this._rectangle;
      },
    },

    /**
     * Gets the map projection used by this tiling scheme.
     * @memberof WebMercatorTilingScheme.prototype
     * @type {MapProjection}
     */
    projection: {
      get: function () {
        return this._projection;
      },
    },
  });

  /**
   * Gets the total number of tiles in the X direction at a specified level-of-detail.
   *
   * @param {Number} level The level-of-detail.
   * @returns {Number} The number of tiles in the X direction at the given level.
   */
  WebMercatorTilingScheme.prototype.getNumberOfXTilesAtLevel = function (level) {
    return this._numberOfLevelZeroTilesX << level;
  };

  /**
   * Gets the total number of tiles in the Y direction at a specified level-of-detail.
   *
   * @param {Number} level The level-of-detail.
   * @returns {Number} The number of tiles in the Y direction at the given level.
   */
  WebMercatorTilingScheme.prototype.getNumberOfYTilesAtLevel = function (level) {
    return this._numberOfLevelZeroTilesY << level;
  };

  /**
   * Transforms a rectangle specified in geodetic radians to the native coordinate system
   * of this tiling scheme.
   *
   * @param {Rectangle} rectangle The rectangle to transform.
   * @param {Rectangle} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the native rectangle if 'result'
   *          is undefined.
   */
  WebMercatorTilingScheme.prototype.rectangleToNativeRectangle = function (
    rectangle,
    result
  ) {
    var projection = this._projection;
    var southwest = projection.project(Rectangle.southwest(rectangle));
    var northeast = projection.project(Rectangle.northeast(rectangle));

    if (!defined(result)) {
      return new Rectangle(southwest.x, southwest.y, northeast.x, northeast.y);
    }

    result.west = southwest.x;
    result.south = southwest.y;
    result.east = northeast.x;
    result.north = northeast.y;
    return result;
  };

  /**
   * Converts tile x, y coordinates and level to a rectangle expressed in the native coordinates
   * of the tiling scheme.
   *
   * @param {Number} x The integer x coordinate of the tile.
   * @param {Number} y The integer y coordinate of the tile.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Object} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the rectangle
   *          if 'result' is undefined.
   */
  WebMercatorTilingScheme.prototype.tileXYToNativeRectangle = function (
    x,
    y,
    level,
    result
  ) {
    var xTiles = this.getNumberOfXTilesAtLevel(level);
    var yTiles = this.getNumberOfYTilesAtLevel(level);

    var xTileWidth =
      (this._rectangleNortheastInMeters.x - this._rectangleSouthwestInMeters.x) /
      xTiles;
    var west = this._rectangleSouthwestInMeters.x + x * xTileWidth;
    var east = this._rectangleSouthwestInMeters.x + (x + 1) * xTileWidth;

    var yTileHeight =
      (this._rectangleNortheastInMeters.y - this._rectangleSouthwestInMeters.y) /
      yTiles;
    var north = this._rectangleNortheastInMeters.y - y * yTileHeight;
    var south = this._rectangleNortheastInMeters.y - (y + 1) * yTileHeight;

    if (!defined(result)) {
      return new Rectangle(west, south, east, north);
    }

    result.west = west;
    result.south = south;
    result.east = east;
    result.north = north;
    return result;
  };

  /**
   * Converts tile x, y coordinates and level to a cartographic rectangle in radians.
   *
   * @param {Number} x The integer x coordinate of the tile.
   * @param {Number} y The integer y coordinate of the tile.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Object} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the rectangle
   *          if 'result' is undefined.
   */
  WebMercatorTilingScheme.prototype.tileXYToRectangle = function (
    x,
    y,
    level,
    result
  ) {
    var nativeRectangle = this.tileXYToNativeRectangle(x, y, level, result);

    var projection = this._projection;
    var southwest = projection.unproject(
      new Cartesian2(nativeRectangle.west, nativeRectangle.south)
    );
    var northeast = projection.unproject(
      new Cartesian2(nativeRectangle.east, nativeRectangle.north)
    );

    nativeRectangle.west = southwest.longitude;
    nativeRectangle.south = southwest.latitude;
    nativeRectangle.east = northeast.longitude;
    nativeRectangle.north = northeast.latitude;
    return nativeRectangle;
  };

  /**
   * Calculates the tile x, y coordinates of the tile containing
   * a given cartographic position.
   *
   * @param {Cartographic} position The position.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Cartesian2} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Cartesian2} The specified 'result', or a new object containing the tile x, y coordinates
   *          if 'result' is undefined.
   */
  WebMercatorTilingScheme.prototype.positionToTileXY = function (
    position,
    level,
    result
  ) {
    var rectangle = this._rectangle;
    if (!Rectangle.contains(rectangle, position)) {
      // outside the bounds of the tiling scheme
      return undefined;
    }

    var xTiles = this.getNumberOfXTilesAtLevel(level);
    var yTiles = this.getNumberOfYTilesAtLevel(level);

    var overallWidth =
      this._rectangleNortheastInMeters.x - this._rectangleSouthwestInMeters.x;
    var xTileWidth = overallWidth / xTiles;
    var overallHeight =
      this._rectangleNortheastInMeters.y - this._rectangleSouthwestInMeters.y;
    var yTileHeight = overallHeight / yTiles;

    var projection = this._projection;

    var webMercatorPosition = projection.project(position);
    var distanceFromWest =
      webMercatorPosition.x - this._rectangleSouthwestInMeters.x;
    var distanceFromNorth =
      this._rectangleNortheastInMeters.y - webMercatorPosition.y;

    var xTileCoordinate = (distanceFromWest / xTileWidth) | 0;
    if (xTileCoordinate >= xTiles) {
      xTileCoordinate = xTiles - 1;
    }
    var yTileCoordinate = (distanceFromNorth / yTileHeight) | 0;
    if (yTileCoordinate >= yTiles) {
      yTileCoordinate = yTiles - 1;
    }

    if (!defined(result)) {
      return new Cartesian2(xTileCoordinate, yTileCoordinate);
    }

    result.x = xTileCoordinate;
    result.y = yTileCoordinate;
    return result;
  };

  var ALL_CHILDREN = 15;

  /**
   * A {@link TerrainProvider} that produces terrain geometry by tessellating height maps
   * retrieved from Elevation Tiles of an an ArcGIS ImageService.
   *
   * @alias ArcGISTiledElevationTerrainProvider
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String|Promise<Resource>|Promise<String>} options.url The URL of the ArcGIS ImageServer service.
   * @param {String} [options.token] The authorization token to use to connect to the service.
   * @param {Ellipsoid} [options.ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   *                    this parameter is ignored and the tiling scheme's ellipsoid is used instead.
   *                    If neither parameter is specified, the WGS84 ellipsoid is used.
   *
   * @example
   * var terrainProvider = new Cesium.ArcGISTiledElevationTerrainProvider({
   *   url : 'https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer',
   *   token : 'KED1aF_I4UzXOHy3BnhwyBHU4l5oY6rO6walkmHoYqGp4XyIWUd5YZUC1ZrLAzvV40pR6gBXQayh0eFA8m6vPg..'
   * });
   * viewer.terrainProvider = terrainProvider;
   *
   *  @see TerrainProvider
   */
  function ArcGISTiledElevationTerrainProvider(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    //>>includeEnd('debug');

    this._resource = undefined;
    this._credit = undefined;
    this._tilingScheme = undefined;
    this._levelZeroMaximumGeometricError = undefined;
    this._maxLevel = undefined;
    this._terrainDataStructure = undefined;
    this._ready = false;
    this._width = undefined;
    this._height = undefined;
    this._encoding = undefined;
    var token = options.token;

    this._hasAvailability = false;
    this._tilesAvailable = undefined;
    this._tilesAvailablityLoaded = undefined;
    this._availableCache = {};

    var that = this;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    this._readyPromise = when(options.url)
      .then(function (url) {
        var resource = Resource.createIfNeeded(url);
        resource.appendForwardSlash();
        if (defined(token)) {
          resource = resource.getDerivedResource({
            queryParameters: {
              token: token,
            },
          });
        }
        that._resource = resource;

        var metadataResource = resource.getDerivedResource({
          queryParameters: {
            f: "pjson",
          },
        });

        return metadataResource.fetchJson();
      })
      .then(function (metadata) {
        var copyrightText = metadata.copyrightText;
        if (defined(copyrightText)) {
          that._credit = new Credit(copyrightText);
        }

        var spatialReference = metadata.spatialReference;
        var wkid = defaultValue(
          spatialReference.latestWkid,
          spatialReference.wkid
        );
        var extent = metadata.extent;
        var tilingSchemeOptions = {
          ellipsoid: ellipsoid,
        };
        if (wkid === 4326) {
          tilingSchemeOptions.rectangle = Rectangle.fromDegrees(
            extent.xmin,
            extent.ymin,
            extent.xmax,
            extent.ymax
          );
          that._tilingScheme = new GeographicTilingScheme(tilingSchemeOptions);
        } else if (wkid === 3857) {
          tilingSchemeOptions.rectangleSouthwestInMeters = new Cartesian2(
            extent.xmin,
            extent.ymin
          );
          tilingSchemeOptions.rectangleNortheastInMeters = new Cartesian2(
            extent.xmax,
            extent.ymax
          );
          that._tilingScheme = new WebMercatorTilingScheme(tilingSchemeOptions);
        } else {
          return when.reject(new RuntimeError("Invalid spatial reference"));
        }

        var tileInfo = metadata.tileInfo;
        if (!defined(tileInfo)) {
          return when.reject(new RuntimeError("tileInfo is required"));
        }

        that._width = tileInfo.rows + 1;
        that._height = tileInfo.cols + 1;
        that._encoding =
          tileInfo.format === "LERC"
            ? HeightmapEncoding$1.LERC
            : HeightmapEncoding$1.NONE;
        that._lodCount = tileInfo.lods.length - 1;

        var hasAvailability = (that._hasAvailability =
          metadata.capabilities.indexOf("Tilemap") !== -1);
        if (hasAvailability) {
          that._tilesAvailable = new TileAvailability(
            that._tilingScheme,
            that._lodCount
          );
          that._tilesAvailable.addAvailableTileRange(
            0,
            0,
            0,
            that._tilingScheme.getNumberOfXTilesAtLevel(0),
            that._tilingScheme.getNumberOfYTilesAtLevel(0)
          );
          that._tilesAvailablityLoaded = new TileAvailability(
            that._tilingScheme,
            that._lodCount
          );
        }

        that._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
          that._tilingScheme.ellipsoid,
          that._width,
          that._tilingScheme.getNumberOfXTilesAtLevel(0)
        );

        if (metadata.bandCount > 1) {
          console.log(
            "ArcGISTiledElevationTerrainProvider: Terrain data has more than 1 band. Using the first one."
          );
        }

        that._terrainDataStructure = {
          elementMultiplier: 1.0,
          lowestEncodedHeight: metadata.minValues[0],
          highestEncodedHeight: metadata.maxValues[0],
        };

        that._ready = true;

        return true;
      })
      .otherwise(function (error) {
        var message =
          "An error occurred while accessing " + that._resource.url + ".";
        TileProviderError.handleError(undefined, that, that._errorEvent, message);
        return when.reject(error);
      });

    this._errorEvent = new Event();
  }

  Object.defineProperties(ArcGISTiledElevationTerrainProvider.prototype, {
    /**
     * Gets an event that is raised when the terrain provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets the credit to display when this terrain provider is active.  Typically this is used to credit
     * the source of the terrain.  This function should not be called before {@link ArcGISTiledElevationTerrainProvider#ready} returns true.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "credit must not be called before ready returns true."
          );
        }
        //>>includeEnd('debug');
        return this._credit;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link ArcGISTiledElevationTerrainProvider#ready} returns true.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {GeographicTilingScheme}
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before ready returns true."
          );
        }
        //>>includeEnd('debug');
        return this._tilingScheme;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets a value indicating whether or not the provider includes a water mask.  The water mask
     * indicates which areas of the globe are water rather than land, so they can be rendered
     * as a reflective surface with animated waves.  This function should not be
     * called before {@link ArcGISTiledElevationTerrainProvider#ready} returns true.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {Boolean}
     */
    hasWaterMask: {
      get: function () {
        return false;
      },
    },

    /**
     * Gets a value indicating whether or not the requested tiles include vertex normals.
     * This function should not be called before {@link ArcGISTiledElevationTerrainProvider#ready} returns true.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {Boolean}
     */
    hasVertexNormals: {
      get: function () {
        return false;
      },
    },
    /**
     * Gets an object that can be used to determine availability of terrain from this provider, such as
     * at points and in rectangles.  This function should not be called before
     * {@link TerrainProvider#ready} returns true.  This property may be undefined if availability
     * information is not available.
     * @memberof ArcGISTiledElevationTerrainProvider.prototype
     * @type {TileAvailability}
     */
    availability: {
      get: function () {
        return undefined;
      },
    },
  });

  /**
   * Requests the geometry for a given tile.  This function should not be called before
   * {@link ArcGISTiledElevationTerrainProvider#ready} returns true.  The result includes terrain
   * data and indicates that all child tiles are available.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry.  If this method
   *          returns undefined instead of a promise, it is an indication that too many requests are already
   *          pending and the request will be retried later.
   */
  ArcGISTiledElevationTerrainProvider.prototype.requestTileGeometry = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug)
    if (!this._ready) {
      throw new DeveloperError(
        "requestTileGeometry must not be called before the terrain provider is ready."
      );
    }
    //>>includeEnd('debug');

    var tileResource = this._resource.getDerivedResource({
      url: "tile/" + level + "/" + y + "/" + x,
      request: request,
    });

    var hasAvailability = this._hasAvailability;
    var availabilityPromise = when.resolve(true);
    var availabilityRequest;
    if (
      hasAvailability &&
      !defined(isTileAvailable(this, level + 1, x * 2, y * 2))
    ) {
      // We need to load child availability
      var availabilityResult = requestAvailability(this, level + 1, x * 2, y * 2);

      availabilityPromise = availabilityResult.promise;
      availabilityRequest = availabilityResult.request;
    }

    var promise = tileResource.fetchArrayBuffer();
    if (!defined(promise) || !defined(availabilityPromise)) {
      return undefined;
    }

    var that = this;
    var tilesAvailable = this._tilesAvailable;
    return when
      .join(promise, availabilityPromise)
      .then(function (result) {
        return new HeightmapTerrainData({
          buffer: result[0],
          width: that._width,
          height: that._height,
          childTileMask: hasAvailability
            ? tilesAvailable.computeChildMaskForTile(level, x, y)
            : ALL_CHILDREN,
          structure: that._terrainDataStructure,
          encoding: that._encoding,
        });
      })
      .otherwise(function (error) {
        if (
          defined(availabilityRequest) &&
          availabilityRequest.state === RequestState$1.CANCELLED
        ) {
          request.cancel();

          // Don't reject the promise till the request is actually cancelled
          // Otherwise it will think the request failed, but it didn't.
          return request.deferred.promise.always(function () {
            request.state = RequestState$1.CANCELLED;
            return when.reject(error);
          });
        }
        return when.reject(error);
      });
  };

  function isTileAvailable(that, level, x, y) {
    if (!that._hasAvailability) {
      return undefined;
    }

    var tilesAvailablityLoaded = that._tilesAvailablityLoaded;
    var tilesAvailable = that._tilesAvailable;

    if (level > that._lodCount) {
      return false;
    }

    // Check if tiles are known to be available
    if (tilesAvailable.isTileAvailable(level, x, y)) {
      return true;
    }

    // or to not be available
    if (tilesAvailablityLoaded.isTileAvailable(level, x, y)) {
      return false;
    }

    return undefined;
  }

  /**
   * Gets the maximum geometric error allowed in a tile at a given level.
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error.
   */
  ArcGISTiledElevationTerrainProvider.prototype.getLevelMaximumGeometricError = function (
    level
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this.ready) {
      throw new DeveloperError(
        "getLevelMaximumGeometricError must not be called before ready returns true."
      );
    }
    //>>includeEnd('debug');

    return this._levelZeroMaximumGeometricError / (1 << level);
  };

  /**
   * Determines whether data for a tile is available to be loaded.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {Boolean} Undefined if not supported, otherwise true or false.
   */
  ArcGISTiledElevationTerrainProvider.prototype.getTileDataAvailable = function (
    x,
    y,
    level
  ) {
    if (!this._hasAvailability) {
      return undefined;
    }

    var result = isTileAvailable(this, level, x, y);
    if (defined(result)) {
      return result;
    }

    requestAvailability(this, level, x, y);

    return undefined;
  };

  /**
   * Makes sure we load availability data for a tile
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {undefined|Promise<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
   */
  ArcGISTiledElevationTerrainProvider.prototype.loadTileDataAvailability = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  function findRange(origin, width, height, data) {
    var endCol = width - 1;
    var endRow = height - 1;

    var value = data[origin.y * width + origin.x];
    var endingIndices = [];
    var range = {
      startX: origin.x,
      startY: origin.y,
      endX: 0,
      endY: 0,
    };

    var corner = new Cartesian2(origin.x + 1, origin.y + 1);
    var doneX = false;
    var doneY = false;
    while (!(doneX && doneY)) {
      // We want to use the original value when checking Y,
      //  so get it before it possibly gets incremented
      var endX = corner.x;

      // If we no longer move in the Y direction we need to check the corner tile in X pass
      var endY = doneY ? corner.y + 1 : corner.y;

      // Check X range
      if (!doneX) {
        for (var y = origin.y; y < endY; ++y) {
          if (data[y * width + corner.x] !== value) {
            doneX = true;
            break;
          }
        }

        if (doneX) {
          endingIndices.push(new Cartesian2(corner.x, origin.y));

          // Use the last good column so we can continue with Y
          --corner.x;
          --endX;
          range.endX = corner.x;
        } else if (corner.x === endCol) {
          range.endX = corner.x;
          doneX = true;
        } else {
          ++corner.x;
        }
      }

      // Check Y range - The corner tile is checked here
      if (!doneY) {
        var col = corner.y * width;
        for (var x = origin.x; x <= endX; ++x) {
          if (data[col + x] !== value) {
            doneY = true;
            break;
          }
        }

        if (doneY) {
          endingIndices.push(new Cartesian2(origin.x, corner.y));

          // Use the last good row so we can continue with X
          --corner.y;
          range.endY = corner.y;
        } else if (corner.y === endRow) {
          range.endY = corner.y;
          doneY = true;
        } else {
          ++corner.y;
        }
      }
    }

    return {
      endingIndices: endingIndices,
      range: range,
      value: value,
    };
  }

  function computeAvailability(x, y, width, height, data) {
    var ranges = [];

    var singleValue = data.every(function (val) {
      return val === data[0];
    });
    if (singleValue) {
      if (data[0] === 1) {
        ranges.push({
          startX: x,
          startY: y,
          endX: x + width - 1,
          endY: y + height - 1,
        });
      }

      return ranges;
    }

    var positions = [new Cartesian2(0, 0)];
    while (positions.length > 0) {
      var origin = positions.pop();
      var result = findRange(origin, width, height, data);

      if (result.value === 1) {
        // Convert range into the array into global tile coordinates
        var range = result.range;
        range.startX += x;
        range.endX += x;
        range.startY += y;
        range.endY += y;
        ranges.push(range);
      }

      var endingIndices = result.endingIndices;
      if (endingIndices.length > 0) {
        positions = positions.concat(endingIndices);
      }
    }

    return ranges;
  }

  function requestAvailability(that, level, x, y) {
    if (!that._hasAvailability) {
      return {};
    }

    // Fetch 128x128 availability list, so we make the minimum amount of requests
    var xOffset = Math.floor(x / 128) * 128;
    var yOffset = Math.floor(y / 128) * 128;

    var dim = Math.min(1 << level, 128);
    var url =
      "tilemap/" + level + "/" + yOffset + "/" + xOffset + "/" + dim + "/" + dim;

    var availableCache = that._availableCache;
    if (defined(availableCache[url])) {
      return availableCache[url];
    }

    var request = new Request({
      throttle: true,
      throttleByServer: true,
      type: RequestType$1.TERRAIN,
    });

    var tilemapResource = that._resource.getDerivedResource({
      url: url,
      request: request,
    });

    var promise = tilemapResource.fetchJson();
    if (!defined(promise)) {
      return {};
    }

    promise = promise.then(function (result) {
      var available = computeAvailability(
        xOffset,
        yOffset,
        dim,
        dim,
        result.data
      );

      // Mark whole area as having availability loaded
      that._tilesAvailablityLoaded.addAvailableTileRange(
        xOffset,
        yOffset,
        xOffset + dim,
        yOffset + dim
      );

      var tilesAvailable = that._tilesAvailable;
      for (var i = 0; i < available.length; ++i) {
        var range = available[i];
        tilesAvailable.addAvailableTileRange(
          level,
          range.startX,
          range.startY,
          range.endX,
          range.endY
        );
      }

      // Conveniently return availability of original tile
      return isTileAvailable(that, level, x, y);
    });

    availableCache[url] = {
      promise: promise,
      request: request,
    };

    promise = promise.always(function (result) {
      delete availableCache[url];

      return result;
    });

    return {
      promise: promise,
      request: request,
    };
  }

  /**
   * ArcType defines the path that should be taken connecting vertices.
   *
   * @enum {Number}
   */
  var ArcType = {
    /**
     * Straight line that does not conform to the surface of the ellipsoid.
     *
     * @type {Number}
     * @constant
     */
    NONE: 0,

    /**
     * Follow geodesic path.
     *
     * @type {Number}
     * @constant
     */
    GEODESIC: 1,

    /**
     * Follow rhumb or loxodrome path.
     *
     * @type {Number}
     * @constant
     */
    RHUMB: 2,
  };
  var ArcType$1 = Object.freeze(ArcType);

  /**
   * A collection of key-value pairs that is stored as a hash for easy
   * lookup but also provides an array for fast iteration.
   * @alias AssociativeArray
   * @constructor
   */
  function AssociativeArray() {
    this._array = [];
    this._hash = {};
  }

  Object.defineProperties(AssociativeArray.prototype, {
    /**
     * Gets the number of items in the collection.
     * @memberof AssociativeArray.prototype
     *
     * @type {Number}
     */
    length: {
      get: function () {
        return this._array.length;
      },
    },
    /**
     * Gets an unordered array of all values in the collection.
     * This is a live array that will automatically reflect the values in the collection,
     * it should not be modified directly.
     * @memberof AssociativeArray.prototype
     *
     * @type {Array}
     */
    values: {
      get: function () {
        return this._array;
      },
    },
  });

  /**
   * Determines if the provided key is in the array.
   *
   * @param {String|Number} key The key to check.
   * @returns {Boolean} <code>true</code> if the key is in the array, <code>false</code> otherwise.
   */
  AssociativeArray.prototype.contains = function (key) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof key !== "string" && typeof key !== "number") {
      throw new DeveloperError("key is required to be a string or number.");
    }
    //>>includeEnd('debug');
    return defined(this._hash[key]);
  };

  /**
   * Associates the provided key with the provided value.  If the key already
   * exists, it is overwritten with the new value.
   *
   * @param {String|Number} key A unique identifier.
   * @param {*} value The value to associate with the provided key.
   */
  AssociativeArray.prototype.set = function (key, value) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof key !== "string" && typeof key !== "number") {
      throw new DeveloperError("key is required to be a string or number.");
    }
    //>>includeEnd('debug');

    var oldValue = this._hash[key];
    if (value !== oldValue) {
      this.remove(key);
      this._hash[key] = value;
      this._array.push(value);
    }
  };

  /**
   * Retrieves the value associated with the provided key.
   *
   * @param {String|Number} key The key whose value is to be retrieved.
   * @returns {*} The associated value, or undefined if the key does not exist in the collection.
   */
  AssociativeArray.prototype.get = function (key) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof key !== "string" && typeof key !== "number") {
      throw new DeveloperError("key is required to be a string or number.");
    }
    //>>includeEnd('debug');
    return this._hash[key];
  };

  /**
   * Removes a key-value pair from the collection.
   *
   * @param {String|Number} key The key to be removed.
   * @returns {Boolean} True if it was removed, false if the key was not in the collection.
   */
  AssociativeArray.prototype.remove = function (key) {
    //>>includeStart('debug', pragmas.debug);
    if (defined(key) && typeof key !== "string" && typeof key !== "number") {
      throw new DeveloperError("key is required to be a string or number.");
    }
    //>>includeEnd('debug');

    var value = this._hash[key];
    var hasValue = defined(value);
    if (hasValue) {
      var array = this._array;
      array.splice(array.indexOf(value), 1);
      delete this._hash[key];
    }
    return hasValue;
  };

  /**
   * Clears the collection.
   */
  AssociativeArray.prototype.removeAll = function () {
    var array = this._array;
    if (array.length > 0) {
      this._hash = {};
      array.length = 0;
    }
  };

  var warnings = {};

  /**
   * Logs a one time message to the console.  Use this function instead of
   * <code>console.log</code> directly since this does not log duplicate messages
   * unless it is called from multiple workers.
   *
   * @function oneTimeWarning
   *
   * @param {String} identifier The unique identifier for this warning.
   * @param {String} [message=identifier] The message to log to the console.
   *
   * @example
   * for(var i=0;i<foo.length;++i) {
   *    if (!defined(foo[i].bar)) {
   *       // Something that can be recovered from but may happen a lot
   *       oneTimeWarning('foo.bar undefined', 'foo.bar is undefined. Setting to 0.');
   *       foo[i].bar = 0;
   *       // ...
   *    }
   * }
   *
   * @private
   */
  function oneTimeWarning(identifier, message) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(identifier)) {
      throw new DeveloperError("identifier is required.");
    }
    //>>includeEnd('debug');

    if (!defined(warnings[identifier])) {
      warnings[identifier] = true;
      console.warn(defaultValue(message, identifier));
    }
  }

  oneTimeWarning.geometryOutlines =
    "Entity geometry outlines are unsupported on terrain. Outlines will be disabled. To enable outlines, disable geometry terrain clamping by explicitly setting height to 0.";

  oneTimeWarning.geometryZIndex =
    "Entity geometry with zIndex are unsupported when height or extrudedHeight are defined.  zIndex will be ignored";

  oneTimeWarning.geometryHeightReference =
    "Entity corridor, ellipse, polygon or rectangle with heightReference must also have a defined height.  heightReference will be ignored";
  oneTimeWarning.geometryExtrudedHeightReference =
    "Entity corridor, ellipse, polygon or rectangle with extrudedHeightReference must also have a defined extrudedHeight.  extrudedHeightReference will be ignored";

  /**
   * Logs a deprecation message to the console.  Use this function instead of
   * <code>console.log</code> directly since this does not log duplicate messages
   * unless it is called from multiple workers.
   *
   * @function deprecationWarning
   *
   * @param {String} identifier The unique identifier for this deprecated API.
   * @param {String} message The message to log to the console.
   *
   * @example
   * // Deprecated function or class
   * function Foo() {
   *    deprecationWarning('Foo', 'Foo was deprecated in Cesium 1.01.  It will be removed in 1.03.  Use newFoo instead.');
   *    // ...
   * }
   *
   * // Deprecated function
   * Bar.prototype.func = function() {
   *    deprecationWarning('Bar.func', 'Bar.func() was deprecated in Cesium 1.01.  It will be removed in 1.03.  Use Bar.newFunc() instead.');
   *    // ...
   * };
   *
   * // Deprecated property
   * Object.defineProperties(Bar.prototype, {
   *     prop : {
   *         get : function() {
   *             deprecationWarning('Bar.prop', 'Bar.prop was deprecated in Cesium 1.01.  It will be removed in 1.03.  Use Bar.newProp instead.');
   *             // ...
   *         },
   *         set : function(value) {
   *             deprecationWarning('Bar.prop', 'Bar.prop was deprecated in Cesium 1.01.  It will be removed in 1.03.  Use Bar.newProp instead.');
   *             // ...
   *         }
   *     }
   * });
   *
   * @private
   */
  function deprecationWarning(identifier, message) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(identifier) || !defined(message)) {
      throw new DeveloperError("identifier and message are required.");
    }
    //>>includeEnd('debug');

    oneTimeWarning(identifier, message);
  }

  var defaultKey;

  /**
   * Object for setting and retrieving the default Bing Maps API key.
   *
   * A Bing API key is only required if you are using {@link BingMapsImageryProvider}
   * or {@link BingMapsGeocoderService}. You can create your own key at
   * {@link https://www.bingmapsportal.com/}.
   *
   * @namespace BingMapsApi
   * @deprecated
   */
  var BingMapsApi = {};

  Object.defineProperties(BingMapsApi, {
    /**
     * The default Bing Maps API key to use if one is not provided to the
     * constructor of an object that uses the Bing Maps API.
     *
     * @type {String}
     * @memberof BingMapsApi
     * @deprecated
     */

    defaultKey: {
      set: function (value) {
        defaultKey = value;
        deprecationWarning(
          "bing-maps-api-default-key",
          "BingMapsApi.defaultKey is deprecated and will be removed in CesiumJS 1.73. Pass your access token directly to the BingMapsGeocoderService or BingMapsImageryProvider constructors."
        );
      },
      get: function () {
        return defaultKey;
      },
    },
  });

  /**
   * Gets the key to use to access the Bing Maps API. If the provided
   * key is defined, it is returned. Otherwise, returns {@link BingMapsApi.defaultKey}.
   * @param {string|null|undefined} providedKey The provided key to use if defined.
   * @returns {string|undefined} The Bing Maps API key to use.
   * @deprecated
   */
  BingMapsApi.getKey = function (providedKey) {
    deprecationWarning(
      "bing-maps-api-get-key",
      "BingMapsApi.getKey is deprecated and will be removed in CesiumJS 1.73. Pass your access token directly to the BingMapsGeocoderService or BingMapsImageryProvider constructors."
    );
    return BingMapsApi._getKeyNoDeprecate(providedKey);
  };

  BingMapsApi._getKeyNoDeprecate = function (providedKey) {
    if (defined(providedKey)) {
      return providedKey;
    }

    return BingMapsApi.defaultKey;
  };

  var url = "https://dev.virtualearth.net/REST/v1/Locations";

  /**
   * Provides geocoding through Bing Maps.
   * @alias BingMapsGeocoderService
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {String} options.key A key to use with the Bing Maps geocoding service
   */
  function BingMapsGeocoderService(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var key = BingMapsApi._getKeyNoDeprecate(options.key);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(key)) {
      throw new DeveloperError("options.key is required.");
    }
    //>>includeEnd('debug');

    this._key = key;

    this._resource = new Resource({
      url: url,
      queryParameters: {
        key: key,
      },
    });
  }

  Object.defineProperties(BingMapsGeocoderService.prototype, {
    /**
     * The URL endpoint for the Bing geocoder service
     * @type {String}
     * @memberof BingMapsGeocoderService.prototype
     * @readonly
     */
    url: {
      get: function () {
        return url;
      },
    },

    /**
     * The key for the Bing geocoder service
     * @type {String}
     * @memberof BingMapsGeocoderService.prototype
     * @readonly
     */
    key: {
      get: function () {
        return this._key;
      },
    },
  });

  /**
   * @function
   *
   * @param {String} query The query to be sent to the geocoder service
   * @returns {Promise<GeocoderService.Result[]>}
   */
  BingMapsGeocoderService.prototype.geocode = function (query) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("query", query);
    //>>includeEnd('debug');

    var resource = this._resource.getDerivedResource({
      queryParameters: {
        query: query,
      },
    });

    return resource.fetchJsonp("jsonp").then(function (result) {
      if (result.resourceSets.length === 0) {
        return [];
      }

      var results = result.resourceSets[0].resources;

      return results.map(function (resource) {
        var bbox = resource.bbox;
        var south = bbox[0];
        var west = bbox[1];
        var north = bbox[2];
        var east = bbox[3];
        return {
          displayName: resource.name,
          destination: Rectangle.fromDegrees(west, south, east, north),
        };
      });
    });
  };

  /**
   * A bounding rectangle given by a corner, width and height.
   * @alias BoundingRectangle
   * @constructor
   *
   * @param {Number} [x=0.0] The x coordinate of the rectangle.
   * @param {Number} [y=0.0] The y coordinate of the rectangle.
   * @param {Number} [width=0.0] The width of the rectangle.
   * @param {Number} [height=0.0] The height of the rectangle.
   *
   * @see BoundingSphere
   * @see Packable
   */
  function BoundingRectangle(x, y, width, height) {
    /**
     * The x coordinate of the rectangle.
     * @type {Number}
     * @default 0.0
     */
    this.x = defaultValue(x, 0.0);

    /**
     * The y coordinate of the rectangle.
     * @type {Number}
     * @default 0.0
     */
    this.y = defaultValue(y, 0.0);

    /**
     * The width of the rectangle.
     * @type {Number}
     * @default 0.0
     */
    this.width = defaultValue(width, 0.0);

    /**
     * The height of the rectangle.
     * @type {Number}
     * @default 0.0
     */
    this.height = defaultValue(height, 0.0);
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  BoundingRectangle.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {BoundingRectangle} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  BoundingRectangle.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.x;
    array[startingIndex++] = value.y;
    array[startingIndex++] = value.width;
    array[startingIndex] = value.height;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {BoundingRectangle} [result] The object into which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided.
   */
  BoundingRectangle.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new BoundingRectangle();
    }
    result.x = array[startingIndex++];
    result.y = array[startingIndex++];
    result.width = array[startingIndex++];
    result.height = array[startingIndex];
    return result;
  };

  /**
   * Computes a bounding rectangle enclosing the list of 2D points.
   * The rectangle is oriented with the corner at the bottom left.
   *
   * @param {Cartesian2[]} positions List of points that the bounding rectangle will enclose.  Each point must have <code>x</code> and <code>y</code> properties.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided.
   */
  BoundingRectangle.fromPoints = function (positions, result) {
    if (!defined(result)) {
      result = new BoundingRectangle();
    }

    if (!defined(positions) || positions.length === 0) {
      result.x = 0;
      result.y = 0;
      result.width = 0;
      result.height = 0;
      return result;
    }

    var length = positions.length;

    var minimumX = positions[0].x;
    var minimumY = positions[0].y;

    var maximumX = positions[0].x;
    var maximumY = positions[0].y;

    for (var i = 1; i < length; i++) {
      var p = positions[i];
      var x = p.x;
      var y = p.y;

      minimumX = Math.min(x, minimumX);
      maximumX = Math.max(x, maximumX);
      minimumY = Math.min(y, minimumY);
      maximumY = Math.max(y, maximumY);
    }

    result.x = minimumX;
    result.y = minimumY;
    result.width = maximumX - minimumX;
    result.height = maximumY - minimumY;
    return result;
  };

  var defaultProjection$1 = new GeographicProjection();
  var fromRectangleLowerLeft = new Cartographic();
  var fromRectangleUpperRight = new Cartographic();
  /**
   * Computes a bounding rectangle from a rectangle.
   *
   * @param {Rectangle} rectangle The valid rectangle used to create a bounding rectangle.
   * @param {Object} [projection=GeographicProjection] The projection used to project the rectangle into 2D.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided.
   */
  BoundingRectangle.fromRectangle = function (rectangle, projection, result) {
    if (!defined(result)) {
      result = new BoundingRectangle();
    }

    if (!defined(rectangle)) {
      result.x = 0;
      result.y = 0;
      result.width = 0;
      result.height = 0;
      return result;
    }

    projection = defaultValue(projection, defaultProjection$1);

    var lowerLeft = projection.project(
      Rectangle.southwest(rectangle, fromRectangleLowerLeft)
    );
    var upperRight = projection.project(
      Rectangle.northeast(rectangle, fromRectangleUpperRight)
    );

    Cartesian2.subtract(upperRight, lowerLeft, upperRight);

    result.x = lowerLeft.x;
    result.y = lowerLeft.y;
    result.width = upperRight.x;
    result.height = upperRight.y;
    return result;
  };

  /**
   * Duplicates a BoundingRectangle instance.
   *
   * @param {BoundingRectangle} rectangle The bounding rectangle to duplicate.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided. (Returns undefined if rectangle is undefined)
   */
  BoundingRectangle.clone = function (rectangle, result) {
    if (!defined(rectangle)) {
      return undefined;
    }

    if (!defined(result)) {
      return new BoundingRectangle(
        rectangle.x,
        rectangle.y,
        rectangle.width,
        rectangle.height
      );
    }

    result.x = rectangle.x;
    result.y = rectangle.y;
    result.width = rectangle.width;
    result.height = rectangle.height;
    return result;
  };

  /**
   * Computes a bounding rectangle that is the union of the left and right bounding rectangles.
   *
   * @param {BoundingRectangle} left A rectangle to enclose in bounding rectangle.
   * @param {BoundingRectangle} right A rectangle to enclose in a bounding rectangle.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided.
   */
  BoundingRectangle.union = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new BoundingRectangle();
    }

    var lowerLeftX = Math.min(left.x, right.x);
    var lowerLeftY = Math.min(left.y, right.y);
    var upperRightX = Math.max(left.x + left.width, right.x + right.width);
    var upperRightY = Math.max(left.y + left.height, right.y + right.height);

    result.x = lowerLeftX;
    result.y = lowerLeftY;
    result.width = upperRightX - lowerLeftX;
    result.height = upperRightY - lowerLeftY;
    return result;
  };

  /**
   * Computes a bounding rectangle by enlarging the provided rectangle until it contains the provided point.
   *
   * @param {BoundingRectangle} rectangle A rectangle to expand.
   * @param {Cartesian2} point A point to enclose in a bounding rectangle.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided.
   */
  BoundingRectangle.expand = function (rectangle, point, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Check.typeOf.object("point", point);
    //>>includeEnd('debug');

    result = BoundingRectangle.clone(rectangle, result);

    var width = point.x - result.x;
    var height = point.y - result.y;

    if (width > result.width) {
      result.width = width;
    } else if (width < 0) {
      result.width -= width;
      result.x = point.x;
    }

    if (height > result.height) {
      result.height = height;
    } else if (height < 0) {
      result.height -= height;
      result.y = point.y;
    }

    return result;
  };

  /**
   * Determines if two rectangles intersect.
   *
   * @param {BoundingRectangle} left A rectangle to check for intersection.
   * @param {BoundingRectangle} right The other rectangle to check for intersection.
   * @returns {Intersect} <code>Intersect.INTESECTING</code> if the rectangles intersect, <code>Intersect.OUTSIDE</code> otherwise.
   */
  BoundingRectangle.intersect = function (left, right) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    //>>includeEnd('debug');

    var leftX = left.x;
    var leftY = left.y;
    var rightX = right.x;
    var rightY = right.y;
    if (
      !(
        leftX > rightX + right.width ||
        leftX + left.width < rightX ||
        leftY + left.height < rightY ||
        leftY > rightY + right.height
      )
    ) {
      return Intersect$1.INTERSECTING;
    }

    return Intersect$1.OUTSIDE;
  };

  /**
   * Compares the provided BoundingRectangles componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {BoundingRectangle} [left] The first BoundingRectangle.
   * @param {BoundingRectangle} [right] The second BoundingRectangle.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  BoundingRectangle.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.x === right.x &&
        left.y === right.y &&
        left.width === right.width &&
        left.height === right.height)
    );
  };

  /**
   * Duplicates this BoundingRectangle instance.
   *
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The modified result parameter or a new BoundingRectangle instance if one was not provided.
   */
  BoundingRectangle.prototype.clone = function (result) {
    return BoundingRectangle.clone(this, result);
  };

  /**
   * Determines if this rectangle intersects with another.
   *
   * @param {BoundingRectangle} right A rectangle to check for intersection.
   * @returns {Intersect} <code>Intersect.INTESECTING</code> if the rectangles intersect, <code>Intersect.OUTSIDE</code> otherwise.
   */
  BoundingRectangle.prototype.intersect = function (right) {
    return BoundingRectangle.intersect(this, right);
  };

  /**
   * Compares this BoundingRectangle against the provided BoundingRectangle componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {BoundingRectangle} [right] The right hand side BoundingRectangle.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  BoundingRectangle.prototype.equals = function (right) {
    return BoundingRectangle.equals(this, right);
  };

  /**
   * Fill an array or a portion of an array with a given value.
   *
   * @param {Array} array The array to fill.
   * @param {*} value The value to fill the array with.
   * @param {Number} [start=0] The index to start filling at.
   * @param {Number} [end=array.length] The index to end stop at.
   *
   * @returns {Array} The resulting array.
   * @private
   */
  function arrayFill(array, value, start, end) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    Check.defined("value", value);
    if (defined(start)) {
      Check.typeOf.number("start", start);
    }
    if (defined(end)) {
      Check.typeOf.number("end", end);
    }
    //>>includeEnd('debug');

    if (typeof array.fill === "function") {
      return array.fill(value, start, end);
    }

    var length = array.length >>> 0;
    var relativeStart = defaultValue(start, 0);
    // If negative, find wrap around position
    var k =
      relativeStart < 0
        ? Math.max(length + relativeStart, 0)
        : Math.min(relativeStart, length);
    var relativeEnd = defaultValue(end, length);
    // If negative, find wrap around position
    var last =
      relativeEnd < 0
        ? Math.max(length + relativeEnd, 0)
        : Math.min(relativeEnd, length);

    // Fill array accordingly
    while (k < last) {
      array[k] = value;
      k++;
    }
    return array;
  }

  /**
   * @private
   */
  var GeometryType = {
    NONE: 0,
    TRIANGLES: 1,
    LINES: 2,
    POLYLINES: 3,
  };
  var GeometryType$1 = Object.freeze(GeometryType);

  /**
   * A 2x2 matrix, indexable as a column-major order array.
   * Constructor parameters are in row-major order for code readability.
   * @alias Matrix2
   * @constructor
   * @implements {ArrayLike<number>}
   *
   * @param {Number} [column0Row0=0.0] The value for column 0, row 0.
   * @param {Number} [column1Row0=0.0] The value for column 1, row 0.
   * @param {Number} [column0Row1=0.0] The value for column 0, row 1.
   * @param {Number} [column1Row1=0.0] The value for column 1, row 1.
   *
   * @see Matrix2.fromColumnMajorArray
   * @see Matrix2.fromRowMajorArray
   * @see Matrix2.fromScale
   * @see Matrix2.fromUniformScale
   * @see Matrix3
   * @see Matrix4
   */
  function Matrix2(column0Row0, column1Row0, column0Row1, column1Row1) {
    this[0] = defaultValue(column0Row0, 0.0);
    this[1] = defaultValue(column0Row1, 0.0);
    this[2] = defaultValue(column1Row0, 0.0);
    this[3] = defaultValue(column1Row1, 0.0);
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Matrix2.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Matrix2} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Matrix2.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value[0];
    array[startingIndex++] = value[1];
    array[startingIndex++] = value[2];
    array[startingIndex++] = value[3];

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Matrix2} [result] The object into which to store the result.
   * @returns {Matrix2} The modified result parameter or a new Matrix2 instance if one was not provided.
   */
  Matrix2.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Matrix2();
    }

    result[0] = array[startingIndex++];
    result[1] = array[startingIndex++];
    result[2] = array[startingIndex++];
    result[3] = array[startingIndex++];
    return result;
  };

  /**
   * Duplicates a Matrix2 instance.
   *
   * @param {Matrix2} matrix The matrix to duplicate.
   * @param {Matrix2} [result] The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter or a new Matrix2 instance if one was not provided. (Returns undefined if matrix is undefined)
   */
  Matrix2.clone = function (matrix, result) {
    if (!defined(matrix)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Matrix2(matrix[0], matrix[2], matrix[1], matrix[3]);
    }
    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    return result;
  };

  /**
   * Creates a Matrix2 from 4 consecutive elements in an array.
   *
   * @param {Number[]} array The array whose 4 consecutive elements correspond to the positions of the matrix.  Assumes column-major order.
   * @param {Number} [startingIndex=0] The offset into the array of the first element, which corresponds to first column first row position in the matrix.
   * @param {Matrix2} [result] The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter or a new Matrix2 instance if one was not provided.
   *
   * @example
   * // Create the Matrix2:
   * // [1.0, 2.0]
   * // [1.0, 2.0]
   *
   * var v = [1.0, 1.0, 2.0, 2.0];
   * var m = Cesium.Matrix2.fromArray(v);
   *
   * // Create same Matrix2 with using an offset into an array
   * var v2 = [0.0, 0.0, 1.0, 1.0, 2.0, 2.0];
   * var m2 = Cesium.Matrix2.fromArray(v2, 2);
   */
  Matrix2.fromArray = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new Matrix2();
    }

    result[0] = array[startingIndex];
    result[1] = array[startingIndex + 1];
    result[2] = array[startingIndex + 2];
    result[3] = array[startingIndex + 3];
    return result;
  };

  /**
   * Creates a Matrix2 instance from a column-major order array.
   *
   * @param {Number[]} values The column-major order array.
   * @param {Matrix2} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix2} The modified result parameter, or a new Matrix2 instance if one was not provided.
   */
  Matrix2.fromColumnMajorArray = function (values, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("values", values);
    //>>includeEnd('debug');

    return Matrix2.clone(values, result);
  };

  /**
   * Creates a Matrix2 instance from a row-major order array.
   * The resulting matrix will be in column-major order.
   *
   * @param {Number[]} values The row-major order array.
   * @param {Matrix2} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix2} The modified result parameter, or a new Matrix2 instance if one was not provided.
   */
  Matrix2.fromRowMajorArray = function (values, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("values", values);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix2(values[0], values[1], values[2], values[3]);
    }
    result[0] = values[0];
    result[1] = values[2];
    result[2] = values[1];
    result[3] = values[3];
    return result;
  };

  /**
   * Computes a Matrix2 instance representing a non-uniform scale.
   *
   * @param {Cartesian2} scale The x and y scale factors.
   * @param {Matrix2} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix2} The modified result parameter, or a new Matrix2 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [7.0, 0.0]
   * //   [0.0, 8.0]
   * var m = Cesium.Matrix2.fromScale(new Cesium.Cartesian2(7.0, 8.0));
   */
  Matrix2.fromScale = function (scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix2(scale.x, 0.0, 0.0, scale.y);
    }

    result[0] = scale.x;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = scale.y;
    return result;
  };

  /**
   * Computes a Matrix2 instance representing a uniform scale.
   *
   * @param {Number} scale The uniform scale factor.
   * @param {Matrix2} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix2} The modified result parameter, or a new Matrix2 instance if one was not provided.
   *
   * @example
   * // Creates
   * //   [2.0, 0.0]
   * //   [0.0, 2.0]
   * var m = Cesium.Matrix2.fromUniformScale(2.0);
   */
  Matrix2.fromUniformScale = function (scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("scale", scale);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Matrix2(scale, 0.0, 0.0, scale);
    }

    result[0] = scale;
    result[1] = 0.0;
    result[2] = 0.0;
    result[3] = scale;
    return result;
  };

  /**
   * Creates a rotation matrix.
   *
   * @param {Number} angle The angle, in radians, of the rotation.  Positive angles are counterclockwise.
   * @param {Matrix2} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Matrix2} The modified result parameter, or a new Matrix2 instance if one was not provided.
   *
   * @example
   * // Rotate a point 45 degrees counterclockwise.
   * var p = new Cesium.Cartesian2(5, 6);
   * var m = Cesium.Matrix2.fromRotation(Cesium.Math.toRadians(45.0));
   * var rotated = Cesium.Matrix2.multiplyByVector(m, p, new Cesium.Cartesian2());
   */
  Matrix2.fromRotation = function (angle, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("angle", angle);
    //>>includeEnd('debug');

    var cosAngle = Math.cos(angle);
    var sinAngle = Math.sin(angle);

    if (!defined(result)) {
      return new Matrix2(cosAngle, -sinAngle, sinAngle, cosAngle);
    }
    result[0] = cosAngle;
    result[1] = sinAngle;
    result[2] = -sinAngle;
    result[3] = cosAngle;
    return result;
  };

  /**
   * Creates an Array from the provided Matrix2 instance.
   * The array will be in column-major order.
   *
   * @param {Matrix2} matrix The matrix to use..
   * @param {Number[]} [result] The Array onto which to store the result.
   * @returns {Number[]} The modified Array parameter or a new Array instance if one was not provided.
   */
  Matrix2.toArray = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return [matrix[0], matrix[1], matrix[2], matrix[3]];
    }
    result[0] = matrix[0];
    result[1] = matrix[1];
    result[2] = matrix[2];
    result[3] = matrix[3];
    return result;
  };

  /**
   * Computes the array index of the element at the provided row and column.
   *
   * @param {Number} row The zero-based index of the row.
   * @param {Number} column The zero-based index of the column.
   * @returns {Number} The index of the element at the provided row and column.
   *
   * @exception {DeveloperError} row must be 0 or 1.
   * @exception {DeveloperError} column must be 0 or 1.
   *
   * @example
   * var myMatrix = new Cesium.Matrix2();
   * var column1Row0Index = Cesium.Matrix2.getElementIndex(1, 0);
   * var column1Row0 = myMatrix[column1Row0Index]
   * myMatrix[column1Row0Index] = 10.0;
   */
  Matrix2.getElementIndex = function (column, row) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("row", row, 0);
    Check.typeOf.number.lessThanOrEquals("row", row, 1);

    Check.typeOf.number.greaterThanOrEquals("column", column, 0);
    Check.typeOf.number.lessThanOrEquals("column", column, 1);
    //>>includeEnd('debug');

    return column * 2 + row;
  };

  /**
   * Retrieves a copy of the matrix column at the provided index as a Cartesian2 instance.
   *
   * @param {Matrix2} matrix The matrix to use.
   * @param {Number} index The zero-based index of the column to retrieve.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0 or 1.
   */
  Matrix2.getColumn = function (matrix, index, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 1);

    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var startIndex = index * 2;
    var x = matrix[startIndex];
    var y = matrix[startIndex + 1];

    result.x = x;
    result.y = y;
    return result;
  };

  /**
   * Computes a new matrix that replaces the specified column in the provided matrix with the provided Cartesian2 instance.
   *
   * @param {Matrix2} matrix The matrix to use.
   * @param {Number} index The zero-based index of the column to set.
   * @param {Cartesian2} cartesian The Cartesian whose values will be assigned to the specified column.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0 or 1.
   */
  Matrix2.setColumn = function (matrix, index, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 1);

    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result = Matrix2.clone(matrix, result);
    var startIndex = index * 2;
    result[startIndex] = cartesian.x;
    result[startIndex + 1] = cartesian.y;
    return result;
  };

  /**
   * Retrieves a copy of the matrix row at the provided index as a Cartesian2 instance.
   *
   * @param {Matrix2} matrix The matrix to use.
   * @param {Number} index The zero-based index of the row to retrieve.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0 or 1.
   */
  Matrix2.getRow = function (matrix, index, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 1);

    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var x = matrix[index];
    var y = matrix[index + 2];

    result.x = x;
    result.y = y;
    return result;
  };

  /**
   * Computes a new matrix that replaces the specified row in the provided matrix with the provided Cartesian2 instance.
   *
   * @param {Matrix2} matrix The matrix to use.
   * @param {Number} index The zero-based index of the row to set.
   * @param {Cartesian2} cartesian The Cartesian whose values will be assigned to the specified row.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   *
   * @exception {DeveloperError} index must be 0 or 1.
   */
  Matrix2.setRow = function (matrix, index, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);

    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThanOrEquals("index", index, 1);

    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result = Matrix2.clone(matrix, result);
    result[index] = cartesian.x;
    result[index + 2] = cartesian.y;
    return result;
  };

  var scratchColumn$2 = new Cartesian2();

  /**
   * Extracts the non-uniform scale assuming the matrix is an affine transformation.
   *
   * @param {Matrix2} matrix The matrix.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Matrix2.getScale = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.x = Cartesian2.magnitude(
      Cartesian2.fromElements(matrix[0], matrix[1], scratchColumn$2)
    );
    result.y = Cartesian2.magnitude(
      Cartesian2.fromElements(matrix[2], matrix[3], scratchColumn$2)
    );
    return result;
  };

  var scratchScale$4 = new Cartesian2();

  /**
   * Computes the maximum scale assuming the matrix is an affine transformation.
   * The maximum scale is the maximum length of the column vectors.
   *
   * @param {Matrix2} matrix The matrix.
   * @returns {Number} The maximum scale.
   */
  Matrix2.getMaximumScale = function (matrix) {
    Matrix2.getScale(matrix, scratchScale$4);
    return Cartesian2.maximumComponent(scratchScale$4);
  };

  /**
   * Computes the product of two matrices.
   *
   * @param {Matrix2} left The first matrix.
   * @param {Matrix2} right The second matrix.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.multiply = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var column0Row0 = left[0] * right[0] + left[2] * right[1];
    var column1Row0 = left[0] * right[2] + left[2] * right[3];
    var column0Row1 = left[1] * right[0] + left[3] * right[1];
    var column1Row1 = left[1] * right[2] + left[3] * right[3];

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column1Row0;
    result[3] = column1Row1;
    return result;
  };

  /**
   * Computes the sum of two matrices.
   *
   * @param {Matrix2} left The first matrix.
   * @param {Matrix2} right The second matrix.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = left[0] + right[0];
    result[1] = left[1] + right[1];
    result[2] = left[2] + right[2];
    result[3] = left[3] + right[3];
    return result;
  };

  /**
   * Computes the difference of two matrices.
   *
   * @param {Matrix2} left The first matrix.
   * @param {Matrix2} right The second matrix.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = left[0] - right[0];
    result[1] = left[1] - right[1];
    result[2] = left[2] - right[2];
    result[3] = left[3] - right[3];
    return result;
  };

  /**
   * Computes the product of a matrix and a column vector.
   *
   * @param {Matrix2} matrix The matrix.
   * @param {Cartesian2} cartesian The column.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter.
   */
  Matrix2.multiplyByVector = function (matrix, cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("cartesian", cartesian);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var x = matrix[0] * cartesian.x + matrix[2] * cartesian.y;
    var y = matrix[1] * cartesian.x + matrix[3] * cartesian.y;

    result.x = x;
    result.y = y;
    return result;
  };

  /**
   * Computes the product of a matrix and a scalar.
   *
   * @param {Matrix2} matrix The matrix.
   * @param {Number} scalar The number to multiply by.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.multiplyByScalar = function (matrix, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0] * scalar;
    result[1] = matrix[1] * scalar;
    result[2] = matrix[2] * scalar;
    result[3] = matrix[3] * scalar;
    return result;
  };

  /**
   * Computes the product of a matrix times a (non-uniform) scale, as if the scale were a scale matrix.
   *
   * @param {Matrix2} matrix The matrix on the left-hand side.
   * @param {Cartesian2} scale The non-uniform scale on the right-hand side.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   *
   *
   * @example
   * // Instead of Cesium.Matrix2.multiply(m, Cesium.Matrix2.fromScale(scale), m);
   * Cesium.Matrix2.multiplyByScale(m, scale, m);
   *
   * @see Matrix2.fromScale
   * @see Matrix2.multiplyByUniformScale
   */
  Matrix2.multiplyByScale = function (matrix, scale, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("scale", scale);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = matrix[0] * scale.x;
    result[1] = matrix[1] * scale.x;
    result[2] = matrix[2] * scale.y;
    result[3] = matrix[3] * scale.y;
    return result;
  };

  /**
   * Creates a negated copy of the provided matrix.
   *
   * @param {Matrix2} matrix The matrix to negate.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.negate = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = -matrix[0];
    result[1] = -matrix[1];
    result[2] = -matrix[2];
    result[3] = -matrix[3];
    return result;
  };

  /**
   * Computes the transpose of the provided matrix.
   *
   * @param {Matrix2} matrix The matrix to transpose.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.transpose = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var column0Row0 = matrix[0];
    var column0Row1 = matrix[2];
    var column1Row0 = matrix[1];
    var column1Row1 = matrix[3];

    result[0] = column0Row0;
    result[1] = column0Row1;
    result[2] = column1Row0;
    result[3] = column1Row1;
    return result;
  };

  /**
   * Computes a matrix, which contains the absolute (unsigned) values of the provided matrix's elements.
   *
   * @param {Matrix2} matrix The matrix with signed elements.
   * @param {Matrix2} result The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter.
   */
  Matrix2.abs = function (matrix, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("matrix", matrix);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result[0] = Math.abs(matrix[0]);
    result[1] = Math.abs(matrix[1]);
    result[2] = Math.abs(matrix[2]);
    result[3] = Math.abs(matrix[3]);

    return result;
  };

  /**
   * Compares the provided matrices componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Matrix2} [left] The first matrix.
   * @param {Matrix2} [right] The second matrix.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Matrix2.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left[0] === right[0] &&
        left[1] === right[1] &&
        left[2] === right[2] &&
        left[3] === right[3])
    );
  };

  /**
   * @private
   */
  Matrix2.equalsArray = function (matrix, array, offset) {
    return (
      matrix[0] === array[offset] &&
      matrix[1] === array[offset + 1] &&
      matrix[2] === array[offset + 2] &&
      matrix[3] === array[offset + 3]
    );
  };

  /**
   * Compares the provided matrices componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Matrix2} [left] The first matrix.
   * @param {Matrix2} [right] The second matrix.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if left and right are within the provided epsilon, <code>false</code> otherwise.
   */
  Matrix2.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0);
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left[0] - right[0]) <= epsilon &&
        Math.abs(left[1] - right[1]) <= epsilon &&
        Math.abs(left[2] - right[2]) <= epsilon &&
        Math.abs(left[3] - right[3]) <= epsilon)
    );
  };

  /**
   * An immutable Matrix2 instance initialized to the identity matrix.
   *
   * @type {Matrix2}
   * @constant
   */
  Matrix2.IDENTITY = Object.freeze(new Matrix2(1.0, 0.0, 0.0, 1.0));

  /**
   * An immutable Matrix2 instance initialized to the zero matrix.
   *
   * @type {Matrix2}
   * @constant
   */
  Matrix2.ZERO = Object.freeze(new Matrix2(0.0, 0.0, 0.0, 0.0));

  /**
   * The index into Matrix2 for column 0, row 0.
   *
   * @type {Number}
   * @constant
   *
   * @example
   * var matrix = new Cesium.Matrix2();
   * matrix[Cesium.Matrix2.COLUMN0ROW0] = 5.0; // set column 0, row 0 to 5.0
   */
  Matrix2.COLUMN0ROW0 = 0;

  /**
   * The index into Matrix2 for column 0, row 1.
   *
   * @type {Number}
   * @constant
   *
   * @example
   * var matrix = new Cesium.Matrix2();
   * matrix[Cesium.Matrix2.COLUMN0ROW1] = 5.0; // set column 0, row 1 to 5.0
   */
  Matrix2.COLUMN0ROW1 = 1;

  /**
   * The index into Matrix2 for column 1, row 0.
   *
   * @type {Number}
   * @constant
   *
   * @example
   * var matrix = new Cesium.Matrix2();
   * matrix[Cesium.Matrix2.COLUMN1ROW0] = 5.0; // set column 1, row 0 to 5.0
   */
  Matrix2.COLUMN1ROW0 = 2;

  /**
   * The index into Matrix2 for column 1, row 1.
   *
   * @type {Number}
   * @constant
   *
   * @example
   * var matrix = new Cesium.Matrix2();
   * matrix[Cesium.Matrix2.COLUMN1ROW1] = 5.0; // set column 1, row 1 to 5.0
   */
  Matrix2.COLUMN1ROW1 = 3;

  Object.defineProperties(Matrix2.prototype, {
    /**
     * Gets the number of items in the collection.
     * @memberof Matrix2.prototype
     *
     * @type {Number}
     */
    length: {
      get: function () {
        return Matrix2.packedLength;
      },
    },
  });

  /**
   * Duplicates the provided Matrix2 instance.
   *
   * @param {Matrix2} [result] The object onto which to store the result.
   * @returns {Matrix2} The modified result parameter or a new Matrix2 instance if one was not provided.
   */
  Matrix2.prototype.clone = function (result) {
    return Matrix2.clone(this, result);
  };

  /**
   * Compares this matrix to the provided matrix componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Matrix2} [right] The right hand side matrix.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  Matrix2.prototype.equals = function (right) {
    return Matrix2.equals(this, right);
  };

  /**
   * Compares this matrix to the provided matrix componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {Matrix2} [right] The right hand side matrix.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  Matrix2.prototype.equalsEpsilon = function (right, epsilon) {
    return Matrix2.equalsEpsilon(this, right, epsilon);
  };

  /**
   * Creates a string representing this Matrix with each row being
   * on a separate line and in the format '(column0, column1)'.
   *
   * @returns {String} A string representing the provided Matrix with each row being on a separate line and in the format '(column0, column1)'.
   */
  Matrix2.prototype.toString = function () {
    return (
      "(" +
      this[0] +
      ", " +
      this[2] +
      ")\n" +
      "(" +
      this[1] +
      ", " +
      this[3] +
      ")"
    );
  };

  /**
   * The type of a geometric primitive, i.e., points, lines, and triangles.
   *
   * @enum {Number}
   */
  var PrimitiveType = {
    /**
     * Points primitive where each vertex (or index) is a separate point.
     *
     * @type {Number}
     * @constant
     */
    POINTS: WebGLConstants$1.POINTS,

    /**
     * Lines primitive where each two vertices (or indices) is a line segment.  Line segments are not necessarily connected.
     *
     * @type {Number}
     * @constant
     */
    LINES: WebGLConstants$1.LINES,

    /**
     * Line loop primitive where each vertex (or index) after the first connects a line to
     * the previous vertex, and the last vertex implicitly connects to the first.
     *
     * @type {Number}
     * @constant
     */
    LINE_LOOP: WebGLConstants$1.LINE_LOOP,

    /**
     * Line strip primitive where each vertex (or index) after the first connects a line to the previous vertex.
     *
     * @type {Number}
     * @constant
     */
    LINE_STRIP: WebGLConstants$1.LINE_STRIP,

    /**
     * Triangles primitive where each three vertices (or indices) is a triangle.  Triangles do not necessarily share edges.
     *
     * @type {Number}
     * @constant
     */
    TRIANGLES: WebGLConstants$1.TRIANGLES,

    /**
     * Triangle strip primitive where each vertex (or index) after the first two connect to
     * the previous two vertices forming a triangle.  For example, this can be used to model a wall.
     *
     * @type {Number}
     * @constant
     */
    TRIANGLE_STRIP: WebGLConstants$1.TRIANGLE_STRIP,

    /**
     * Triangle fan primitive where each vertex (or index) after the first two connect to
     * the previous vertex and the first vertex forming a triangle.  For example, this can be used
     * to model a cone or circle.
     *
     * @type {Number}
     * @constant
     */
    TRIANGLE_FAN: WebGLConstants$1.TRIANGLE_FAN,
  };

  /**
   * @private
   */
  PrimitiveType.validate = function (primitiveType) {
    return (
      primitiveType === PrimitiveType.POINTS ||
      primitiveType === PrimitiveType.LINES ||
      primitiveType === PrimitiveType.LINE_LOOP ||
      primitiveType === PrimitiveType.LINE_STRIP ||
      primitiveType === PrimitiveType.TRIANGLES ||
      primitiveType === PrimitiveType.TRIANGLE_STRIP ||
      primitiveType === PrimitiveType.TRIANGLE_FAN
    );
  };

  var PrimitiveType$1 = Object.freeze(PrimitiveType);

  /**
   * A geometry representation with attributes forming vertices and optional index data
   * defining primitives.  Geometries and an {@link Appearance}, which describes the shading,
   * can be assigned to a {@link Primitive} for visualization.  A <code>Primitive</code> can
   * be created from many heterogeneous - in many cases - geometries for performance.
   * <p>
   * Geometries can be transformed and optimized using functions in {@link GeometryPipeline}.
   * </p>
   *
   * @alias Geometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {GeometryAttributes} options.attributes Attributes, which make up the geometry's vertices.
   * @param {PrimitiveType} [options.primitiveType=PrimitiveType.TRIANGLES] The type of primitives in the geometry.
   * @param {Uint16Array|Uint32Array} [options.indices] Optional index data that determines the primitives in the geometry.
   * @param {BoundingSphere} [options.boundingSphere] An optional bounding sphere that fully enclosed the geometry.
   *
   * @see PolygonGeometry
   * @see RectangleGeometry
   * @see EllipseGeometry
   * @see CircleGeometry
   * @see WallGeometry
   * @see SimplePolylineGeometry
   * @see BoxGeometry
   * @see EllipsoidGeometry
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Geometry%20and%20Appearances.html|Geometry and Appearances Demo}
   *
   * @example
   * // Create geometry with a position attribute and indexed lines.
   * var positions = new Float64Array([
   *   0.0, 0.0, 0.0,
   *   7500000.0, 0.0, 0.0,
   *   0.0, 7500000.0, 0.0
   * ]);
   *
   * var geometry = new Cesium.Geometry({
   *   attributes : {
   *     position : new Cesium.GeometryAttribute({
   *       componentDatatype : Cesium.ComponentDatatype.DOUBLE,
   *       componentsPerAttribute : 3,
   *       values : positions
   *     })
   *   },
   *   indices : new Uint16Array([0, 1, 1, 2, 2, 0]),
   *   primitiveType : Cesium.PrimitiveType.LINES,
   *   boundingSphere : Cesium.BoundingSphere.fromVertices(positions)
   * });
   */
  function Geometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options.attributes", options.attributes);
    //>>includeEnd('debug');

    /**
     * Attributes, which make up the geometry's vertices.  Each property in this object corresponds to a
     * {@link GeometryAttribute} containing the attribute's data.
     * <p>
     * Attributes are always stored non-interleaved in a Geometry.
     * </p>
     * <p>
     * There are reserved attribute names with well-known semantics.  The following attributes
     * are created by a Geometry (depending on the provided {@link VertexFormat}.
     * <ul>
     *    <li><code>position</code> - 3D vertex position.  64-bit floating-point (for precision).  3 components per attribute.  See {@link VertexFormat#position}.</li>
     *    <li><code>normal</code> - Normal (normalized), commonly used for lighting.  32-bit floating-point.  3 components per attribute.  See {@link VertexFormat#normal}.</li>
     *    <li><code>st</code> - 2D texture coordinate.  32-bit floating-point.  2 components per attribute.  See {@link VertexFormat#st}.</li>
     *    <li><code>bitangent</code> - Bitangent (normalized), used for tangent-space effects like bump mapping.  32-bit floating-point.  3 components per attribute.  See {@link VertexFormat#bitangent}.</li>
     *    <li><code>tangent</code> - Tangent (normalized), used for tangent-space effects like bump mapping.  32-bit floating-point.  3 components per attribute.  See {@link VertexFormat#tangent}.</li>
     * </ul>
     * </p>
     * <p>
     * The following attribute names are generally not created by a Geometry, but are added
     * to a Geometry by a {@link Primitive} or {@link GeometryPipeline} functions to prepare
     * the geometry for rendering.
     * <ul>
     *    <li><code>position3DHigh</code> - High 32 bits for encoded 64-bit position computed with {@link GeometryPipeline.encodeAttribute}.  32-bit floating-point.  4 components per attribute.</li>
     *    <li><code>position3DLow</code> - Low 32 bits for encoded 64-bit position computed with {@link GeometryPipeline.encodeAttribute}.  32-bit floating-point.  4 components per attribute.</li>
     *    <li><code>position3DHigh</code> - High 32 bits for encoded 64-bit 2D (Columbus view) position computed with {@link GeometryPipeline.encodeAttribute}.  32-bit floating-point.  4 components per attribute.</li>
     *    <li><code>position2DLow</code> - Low 32 bits for encoded 64-bit 2D (Columbus view) position computed with {@link GeometryPipeline.encodeAttribute}.  32-bit floating-point.  4 components per attribute.</li>
     *    <li><code>color</code> - RGBA color (normalized) usually from {@link GeometryInstance#color}.  32-bit floating-point.  4 components per attribute.</li>
     *    <li><code>pickColor</code> - RGBA color used for picking.  32-bit floating-point.  4 components per attribute.</li>
     * </ul>
     * </p>
     *
     * @type GeometryAttributes
     *
     * @default undefined
     *
     *
     * @example
     * geometry.attributes.position = new Cesium.GeometryAttribute({
     *   componentDatatype : Cesium.ComponentDatatype.FLOAT,
     *   componentsPerAttribute : 3,
     *   values : new Float32Array(0)
     * });
     *
     * @see GeometryAttribute
     * @see VertexFormat
     */
    this.attributes = options.attributes;

    /**
     * Optional index data that - along with {@link Geometry#primitiveType} -
     * determines the primitives in the geometry.
     *
     * @type Array
     *
     * @default undefined
     */
    this.indices = options.indices;

    /**
     * The type of primitives in the geometry.  This is most often {@link PrimitiveType.TRIANGLES},
     * but can varying based on the specific geometry.
     *
     * @type PrimitiveType
     *
     * @default undefined
     */
    this.primitiveType = defaultValue(
      options.primitiveType,
      PrimitiveType$1.TRIANGLES
    );

    /**
     * An optional bounding sphere that fully encloses the geometry.  This is
     * commonly used for culling.
     *
     * @type BoundingSphere
     *
     * @default undefined
     */
    this.boundingSphere = options.boundingSphere;

    /**
     * @private
     */
    this.geometryType = defaultValue(options.geometryType, GeometryType$1.NONE);

    /**
     * @private
     */
    this.boundingSphereCV = options.boundingSphereCV;

    /**
     * Used for computing the bounding sphere for geometry using the applyOffset vertex attribute
     * @private
     */
    this.offsetAttribute = options.offsetAttribute;
  }

  /**
   * Computes the number of vertices in a geometry.  The runtime is linear with
   * respect to the number of attributes in a vertex, not the number of vertices.
   *
   * @param {Geometry} geometry The geometry.
   * @returns {Number} The number of vertices in the geometry.
   *
   * @example
   * var numVertices = Cesium.Geometry.computeNumberOfVertices(geometry);
   */
  Geometry.computeNumberOfVertices = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("geometry", geometry);
    //>>includeEnd('debug');

    var numberOfVertices = -1;
    for (var property in geometry.attributes) {
      if (
        geometry.attributes.hasOwnProperty(property) &&
        defined(geometry.attributes[property]) &&
        defined(geometry.attributes[property].values)
      ) {
        var attribute = geometry.attributes[property];
        var num = attribute.values.length / attribute.componentsPerAttribute;
        //>>includeStart('debug', pragmas.debug);
        if (numberOfVertices !== num && numberOfVertices !== -1) {
          throw new DeveloperError(
            "All attribute lists must have the same number of attributes."
          );
        }
        //>>includeEnd('debug');
        numberOfVertices = num;
      }
    }

    return numberOfVertices;
  };

  var rectangleCenterScratch = new Cartographic();
  var enuCenterScratch = new Cartesian3();
  var fixedFrameToEnuScratch = new Matrix4();
  var boundingRectanglePointsCartographicScratch = [
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
  ];
  var boundingRectanglePointsEnuScratch = [
    new Cartesian2(),
    new Cartesian2(),
    new Cartesian2(),
  ];
  var points2DScratch = [new Cartesian2(), new Cartesian2(), new Cartesian2()];
  var pointEnuScratch = new Cartesian3();
  var enuRotationScratch = new Quaternion();
  var enuRotationMatrixScratch = new Matrix4();
  var rotation2DScratch = new Matrix2();

  /**
   * For remapping texture coordinates when rendering GroundPrimitives with materials.
   * GroundPrimitive texture coordinates are computed to align with the cartographic coordinate system on the globe.
   * However, EllipseGeometry, RectangleGeometry, and PolygonGeometry all bake rotations to per-vertex texture coordinates
   * using different strategies.
   *
   * This method is used by EllipseGeometry and PolygonGeometry to approximate the same visual effect.
   * We encapsulate rotation and scale by computing a "transformed" texture coordinate system and computing
   * a set of reference points from which "cartographic" texture coordinates can be remapped to the "transformed"
   * system using distances to lines in 2D.
   *
   * This approximation becomes less accurate as the covered area increases, especially for GroundPrimitives near the poles,
   * but is generally reasonable for polygons and ellipses around the size of USA states.
   *
   * RectangleGeometry has its own version of this method that computes remapping coordinates using cartographic space
   * as an intermediary instead of local ENU, which is more accurate for large-area rectangles.
   *
   * @param {Cartesian3[]} positions Array of positions outlining the geometry
   * @param {Number} stRotation Texture coordinate rotation.
   * @param {Ellipsoid} ellipsoid Ellipsoid for projecting and generating local vectors.
   * @param {Rectangle} boundingRectangle Bounding rectangle around the positions.
   * @returns {Number[]} An array of 6 numbers specifying [minimum point, u extent, v extent] as points in the "cartographic" system.
   * @private
   */
  Geometry._textureCoordinateRotationPoints = function (
    positions,
    stRotation,
    ellipsoid,
    boundingRectangle
  ) {
    var i;

    // Create a local east-north-up coordinate system centered on the polygon's bounding rectangle.
    // Project the southwest, northwest, and southeast corners of the bounding rectangle into the plane of ENU as 2D points.
    // These are the equivalents of (0,0), (0,1), and (1,0) in the texture coordiante system computed in ShadowVolumeAppearanceFS,
    // aka "ENU texture space."
    var rectangleCenter = Rectangle.center(
      boundingRectangle,
      rectangleCenterScratch
    );
    var enuCenter = Cartographic.toCartesian(
      rectangleCenter,
      ellipsoid,
      enuCenterScratch
    );
    var enuToFixedFrame = Transforms.eastNorthUpToFixedFrame(
      enuCenter,
      ellipsoid,
      fixedFrameToEnuScratch
    );
    var fixedFrameToEnu = Matrix4.inverse(
      enuToFixedFrame,
      fixedFrameToEnuScratch
    );

    var boundingPointsEnu = boundingRectanglePointsEnuScratch;
    var boundingPointsCarto = boundingRectanglePointsCartographicScratch;

    boundingPointsCarto[0].longitude = boundingRectangle.west;
    boundingPointsCarto[0].latitude = boundingRectangle.south;

    boundingPointsCarto[1].longitude = boundingRectangle.west;
    boundingPointsCarto[1].latitude = boundingRectangle.north;

    boundingPointsCarto[2].longitude = boundingRectangle.east;
    boundingPointsCarto[2].latitude = boundingRectangle.south;

    var posEnu = pointEnuScratch;

    for (i = 0; i < 3; i++) {
      Cartographic.toCartesian(boundingPointsCarto[i], ellipsoid, posEnu);
      posEnu = Matrix4.multiplyByPointAsVector(fixedFrameToEnu, posEnu, posEnu);
      boundingPointsEnu[i].x = posEnu.x;
      boundingPointsEnu[i].y = posEnu.y;
    }

    // Rotate each point in the polygon around the up vector in the ENU by -stRotation and project into ENU as 2D.
    // Compute the bounding box of these rotated points in the 2D ENU plane.
    // Rotate the corners back by stRotation, then compute their equivalents in the ENU texture space using the corners computed earlier.
    var rotation = Quaternion.fromAxisAngle(
      Cartesian3.UNIT_Z,
      -stRotation,
      enuRotationScratch
    );
    var textureMatrix = Matrix3.fromQuaternion(
      rotation,
      enuRotationMatrixScratch
    );

    var positionsLength = positions.length;
    var enuMinX = Number.POSITIVE_INFINITY;
    var enuMinY = Number.POSITIVE_INFINITY;
    var enuMaxX = Number.NEGATIVE_INFINITY;
    var enuMaxY = Number.NEGATIVE_INFINITY;
    for (i = 0; i < positionsLength; i++) {
      posEnu = Matrix4.multiplyByPointAsVector(
        fixedFrameToEnu,
        positions[i],
        posEnu
      );
      posEnu = Matrix3.multiplyByVector(textureMatrix, posEnu, posEnu);

      enuMinX = Math.min(enuMinX, posEnu.x);
      enuMinY = Math.min(enuMinY, posEnu.y);
      enuMaxX = Math.max(enuMaxX, posEnu.x);
      enuMaxY = Math.max(enuMaxY, posEnu.y);
    }

    var toDesiredInComputed = Matrix2.fromRotation(stRotation, rotation2DScratch);

    var points2D = points2DScratch;
    points2D[0].x = enuMinX;
    points2D[0].y = enuMinY;

    points2D[1].x = enuMinX;
    points2D[1].y = enuMaxY;

    points2D[2].x = enuMaxX;
    points2D[2].y = enuMinY;

    var boundingEnuMin = boundingPointsEnu[0];
    var boundingPointsWidth = boundingPointsEnu[2].x - boundingEnuMin.x;
    var boundingPointsHeight = boundingPointsEnu[1].y - boundingEnuMin.y;

    for (i = 0; i < 3; i++) {
      var point2D = points2D[i];
      // rotate back
      Matrix2.multiplyByVector(toDesiredInComputed, point2D, point2D);

      // Convert point into east-north texture coordinate space
      point2D.x = (point2D.x - boundingEnuMin.x) / boundingPointsWidth;
      point2D.y = (point2D.y - boundingEnuMin.y) / boundingPointsHeight;
    }

    var minXYCorner = points2D[0];
    var maxYCorner = points2D[1];
    var maxXCorner = points2D[2];
    var result = new Array(6);
    Cartesian2.pack(minXYCorner, result);
    Cartesian2.pack(maxYCorner, result, 2);
    Cartesian2.pack(maxXCorner, result, 4);

    return result;
  };

  /**
   * Values and type information for geometry attributes.  A {@link Geometry}
   * generally contains one or more attributes.  All attributes together form
   * the geometry's vertices.
   *
   * @alias GeometryAttribute
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {ComponentDatatype} [options.componentDatatype] The datatype of each component in the attribute, e.g., individual elements in values.
   * @param {Number} [options.componentsPerAttribute] A number between 1 and 4 that defines the number of components in an attributes.
   * @param {Boolean} [options.normalize=false] When <code>true</code> and <code>componentDatatype</code> is an integer format, indicate that the components should be mapped to the range [0, 1] (unsigned) or [-1, 1] (signed) when they are accessed as floating-point for rendering.
   * @param {number[]|Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array} [options.values] The values for the attributes stored in a typed array.
   *
   * @exception {DeveloperError} options.componentsPerAttribute must be between 1 and 4.
   *
   *
   * @example
   * var geometry = new Cesium.Geometry({
   *   attributes : {
   *     position : new Cesium.GeometryAttribute({
   *       componentDatatype : Cesium.ComponentDatatype.FLOAT,
   *       componentsPerAttribute : 3,
   *       values : new Float32Array([
   *         0.0, 0.0, 0.0,
   *         7500000.0, 0.0, 0.0,
   *         0.0, 7500000.0, 0.0
   *       ])
   *     })
   *   },
   *   primitiveType : Cesium.PrimitiveType.LINE_LOOP
   * });
   *
   * @see Geometry
   */
  function GeometryAttribute(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.componentDatatype)) {
      throw new DeveloperError("options.componentDatatype is required.");
    }
    if (!defined(options.componentsPerAttribute)) {
      throw new DeveloperError("options.componentsPerAttribute is required.");
    }
    if (
      options.componentsPerAttribute < 1 ||
      options.componentsPerAttribute > 4
    ) {
      throw new DeveloperError(
        "options.componentsPerAttribute must be between 1 and 4."
      );
    }
    if (!defined(options.values)) {
      throw new DeveloperError("options.values is required.");
    }
    //>>includeEnd('debug');

    /**
     * The datatype of each component in the attribute, e.g., individual elements in
     * {@link GeometryAttribute#values}.
     *
     * @type ComponentDatatype
     *
     * @default undefined
     */
    this.componentDatatype = options.componentDatatype;

    /**
     * A number between 1 and 4 that defines the number of components in an attributes.
     * For example, a position attribute with x, y, and z components would have 3 as
     * shown in the code example.
     *
     * @type Number
     *
     * @default undefined
     *
     * @example
     * attribute.componentDatatype = Cesium.ComponentDatatype.FLOAT;
     * attribute.componentsPerAttribute = 3;
     * attribute.values = new Float32Array([
     *   0.0, 0.0, 0.0,
     *   7500000.0, 0.0, 0.0,
     *   0.0, 7500000.0, 0.0
     * ]);
     */
    this.componentsPerAttribute = options.componentsPerAttribute;

    /**
     * When <code>true</code> and <code>componentDatatype</code> is an integer format,
     * indicate that the components should be mapped to the range [0, 1] (unsigned)
     * or [-1, 1] (signed) when they are accessed as floating-point for rendering.
     * <p>
     * This is commonly used when storing colors using {@link ComponentDatatype.UNSIGNED_BYTE}.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     *
     * @example
     * attribute.componentDatatype = Cesium.ComponentDatatype.UNSIGNED_BYTE;
     * attribute.componentsPerAttribute = 4;
     * attribute.normalize = true;
     * attribute.values = new Uint8Array([
     *   Cesium.Color.floatToByte(color.red),
     *   Cesium.Color.floatToByte(color.green),
     *   Cesium.Color.floatToByte(color.blue),
     *   Cesium.Color.floatToByte(color.alpha)
     * ]);
     */
    this.normalize = defaultValue(options.normalize, false);

    /**
     * The values for the attributes stored in a typed array.  In the code example,
     * every three elements in <code>values</code> defines one attributes since
     * <code>componentsPerAttribute</code> is 3.
     *
     * @type {number[]|Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array}
     *
     * @default undefined
     *
     * @example
     * attribute.componentDatatype = Cesium.ComponentDatatype.FLOAT;
     * attribute.componentsPerAttribute = 3;
     * attribute.values = new Float32Array([
     *   0.0, 0.0, 0.0,
     *   7500000.0, 0.0, 0.0,
     *   0.0, 7500000.0, 0.0
     * ]);
     */
    this.values = options.values;
  }

  /**
   * Attributes, which make up a geometry's vertices.  Each property in this object corresponds to a
   * {@link GeometryAttribute} containing the attribute's data.
   * <p>
   * Attributes are always stored non-interleaved in a Geometry.
   * </p>
   *
   * @alias GeometryAttributes
   * @constructor
   */
  function GeometryAttributes(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The 3D position attribute.
     * <p>
     * 64-bit floating-point (for precision).  3 components per attribute.
     * </p>
     *
     * @type GeometryAttribute
     *
     * @default undefined
     */
    this.position = options.position;

    /**
     * The normal attribute (normalized), which is commonly used for lighting.
     * <p>
     * 32-bit floating-point.  3 components per attribute.
     * </p>
     *
     * @type GeometryAttribute
     *
     * @default undefined
     */
    this.normal = options.normal;

    /**
     * The 2D texture coordinate attribute.
     * <p>
     * 32-bit floating-point.  2 components per attribute
     * </p>
     *
     * @type GeometryAttribute
     *
     * @default undefined
     */
    this.st = options.st;

    /**
     * The bitangent attribute (normalized), which is used for tangent-space effects like bump mapping.
     * <p>
     * 32-bit floating-point.  3 components per attribute.
     * </p>
     *
     * @type GeometryAttribute
     *
     * @default undefined
     */
    this.bitangent = options.bitangent;

    /**
     * The tangent attribute (normalized), which is used for tangent-space effects like bump mapping.
     * <p>
     * 32-bit floating-point.  3 components per attribute.
     * </p>
     *
     * @type GeometryAttribute
     *
     * @default undefined
     */
    this.tangent = options.tangent;

    /**
     * The color attribute.
     * <p>
     * 8-bit unsigned integer. 4 components per attribute.
     * </p>
     *
     * @type GeometryAttribute
     *
     * @default undefined
     */
    this.color = options.color;
  }

  /**
   * Represents which vertices should have a value of `true` for the `applyOffset` attribute
   * @private
   */
  var GeometryOffsetAttribute = {
    NONE: 0,
    TOP: 1,
    ALL: 2,
  };
  var GeometryOffsetAttribute$1 = Object.freeze(GeometryOffsetAttribute);

  /**
   * A vertex format defines what attributes make up a vertex.  A VertexFormat can be provided
   * to a {@link Geometry} to request that certain properties be computed, e.g., just position,
   * position and normal, etc.
   *
   * @param {Object} [options] An object with boolean properties corresponding to VertexFormat properties as shown in the code example.
   *
   * @alias VertexFormat
   * @constructor
   *
   * @example
   * // Create a vertex format with position and 2D texture coordinate attributes.
   * var format = new Cesium.VertexFormat({
   *   position : true,
   *   st : true
   * });
   *
   * @see Geometry#attributes
   * @see Packable
   */
  function VertexFormat(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * When <code>true</code>, the vertex has a 3D position attribute.
     * <p>
     * 64-bit floating-point (for precision).  3 components per attribute.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.position = defaultValue(options.position, false);

    /**
     * When <code>true</code>, the vertex has a normal attribute (normalized), which is commonly used for lighting.
     * <p>
     * 32-bit floating-point.  3 components per attribute.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.normal = defaultValue(options.normal, false);

    /**
     * When <code>true</code>, the vertex has a 2D texture coordinate attribute.
     * <p>
     * 32-bit floating-point.  2 components per attribute
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.st = defaultValue(options.st, false);

    /**
     * When <code>true</code>, the vertex has a bitangent attribute (normalized), which is used for tangent-space effects like bump mapping.
     * <p>
     * 32-bit floating-point.  3 components per attribute.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.bitangent = defaultValue(options.bitangent, false);

    /**
     * When <code>true</code>, the vertex has a tangent attribute (normalized), which is used for tangent-space effects like bump mapping.
     * <p>
     * 32-bit floating-point.  3 components per attribute.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.tangent = defaultValue(options.tangent, false);

    /**
     * When <code>true</code>, the vertex has an RGB color attribute.
     * <p>
     * 8-bit unsigned byte.  3 components per attribute.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.color = defaultValue(options.color, false);
  }

  /**
   * An immutable vertex format with only a position attribute.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   */
  VertexFormat.POSITION_ONLY = Object.freeze(
    new VertexFormat({
      position: true,
    })
  );

  /**
   * An immutable vertex format with position and normal attributes.
   * This is compatible with per-instance color appearances like {@link PerInstanceColorAppearance}.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   * @see VertexFormat#normal
   */
  VertexFormat.POSITION_AND_NORMAL = Object.freeze(
    new VertexFormat({
      position: true,
      normal: true,
    })
  );

  /**
   * An immutable vertex format with position, normal, and st attributes.
   * This is compatible with {@link MaterialAppearance} when {@link MaterialAppearance#materialSupport}
   * is <code>TEXTURED/code>.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   * @see VertexFormat#normal
   * @see VertexFormat#st
   */
  VertexFormat.POSITION_NORMAL_AND_ST = Object.freeze(
    new VertexFormat({
      position: true,
      normal: true,
      st: true,
    })
  );

  /**
   * An immutable vertex format with position and st attributes.
   * This is compatible with {@link EllipsoidSurfaceAppearance}.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   * @see VertexFormat#st
   */
  VertexFormat.POSITION_AND_ST = Object.freeze(
    new VertexFormat({
      position: true,
      st: true,
    })
  );

  /**
   * An immutable vertex format with position and color attributes.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   * @see VertexFormat#color
   */
  VertexFormat.POSITION_AND_COLOR = Object.freeze(
    new VertexFormat({
      position: true,
      color: true,
    })
  );

  /**
   * An immutable vertex format with well-known attributes: position, normal, st, tangent, and bitangent.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   * @see VertexFormat#normal
   * @see VertexFormat#st
   * @see VertexFormat#tangent
   * @see VertexFormat#bitangent
   */
  VertexFormat.ALL = Object.freeze(
    new VertexFormat({
      position: true,
      normal: true,
      st: true,
      tangent: true,
      bitangent: true,
    })
  );

  /**
   * An immutable vertex format with position, normal, and st attributes.
   * This is compatible with most appearances and materials; however
   * normal and st attributes are not always required.  When this is
   * known in advance, another <code>VertexFormat</code> should be used.
   *
   * @type {VertexFormat}
   * @constant
   *
   * @see VertexFormat#position
   * @see VertexFormat#normal
   */
  VertexFormat.DEFAULT = VertexFormat.POSITION_NORMAL_AND_ST;

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  VertexFormat.packedLength = 6;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {VertexFormat} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  VertexFormat.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.position ? 1.0 : 0.0;
    array[startingIndex++] = value.normal ? 1.0 : 0.0;
    array[startingIndex++] = value.st ? 1.0 : 0.0;
    array[startingIndex++] = value.tangent ? 1.0 : 0.0;
    array[startingIndex++] = value.bitangent ? 1.0 : 0.0;
    array[startingIndex] = value.color ? 1.0 : 0.0;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {VertexFormat} [result] The object into which to store the result.
   * @returns {VertexFormat} The modified result parameter or a new VertexFormat instance if one was not provided.
   */
  VertexFormat.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new VertexFormat();
    }

    result.position = array[startingIndex++] === 1.0;
    result.normal = array[startingIndex++] === 1.0;
    result.st = array[startingIndex++] === 1.0;
    result.tangent = array[startingIndex++] === 1.0;
    result.bitangent = array[startingIndex++] === 1.0;
    result.color = array[startingIndex] === 1.0;
    return result;
  };

  /**
   * Duplicates a VertexFormat instance.
   *
   * @param {VertexFormat} vertexFormat The vertex format to duplicate.
   * @param {VertexFormat} [result] The object onto which to store the result.
   * @returns {VertexFormat} The modified result parameter or a new VertexFormat instance if one was not provided. (Returns undefined if vertexFormat is undefined)
   */
  VertexFormat.clone = function (vertexFormat, result) {
    if (!defined(vertexFormat)) {
      return undefined;
    }
    if (!defined(result)) {
      result = new VertexFormat();
    }

    result.position = vertexFormat.position;
    result.normal = vertexFormat.normal;
    result.st = vertexFormat.st;
    result.tangent = vertexFormat.tangent;
    result.bitangent = vertexFormat.bitangent;
    result.color = vertexFormat.color;
    return result;
  };

  var diffScratch = new Cartesian3();

  /**
   * Describes a cube centered at the origin.
   *
   * @alias BoxGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.minimum The minimum x, y, and z coordinates of the box.
   * @param {Cartesian3} options.maximum The maximum x, y, and z coordinates of the box.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @see BoxGeometry.fromDimensions
   * @see BoxGeometry.createGeometry
   * @see Packable
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Box.html|Cesium Sandcastle Box Demo}
   *
   * @example
   * var box = new Cesium.BoxGeometry({
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY,
   *   maximum : new Cesium.Cartesian3(250000.0, 250000.0, 250000.0),
   *   minimum : new Cesium.Cartesian3(-250000.0, -250000.0, -250000.0)
   * });
   * var geometry = Cesium.BoxGeometry.createGeometry(box);
   */
  function BoxGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var min = options.minimum;
    var max = options.maximum;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("min", min);
    Check.typeOf.object("max", max);
    if (
      defined(options.offsetAttribute) &&
      options.offsetAttribute === GeometryOffsetAttribute$1.TOP
    ) {
      throw new DeveloperError(
        "GeometryOffsetAttribute.TOP is not a supported options.offsetAttribute for this geometry."
      );
    }
    //>>includeEnd('debug');

    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);

    this._minimum = Cartesian3.clone(min);
    this._maximum = Cartesian3.clone(max);
    this._vertexFormat = vertexFormat;
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createBoxGeometry";
  }

  /**
   * Creates a cube centered at the origin given its dimensions.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.dimensions The width, depth, and height of the box stored in the x, y, and z coordinates of the <code>Cartesian3</code>, respectively.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @returns {BoxGeometry}
   *
   * @exception {DeveloperError} All dimensions components must be greater than or equal to zero.
   *
   *
   * @example
   * var box = Cesium.BoxGeometry.fromDimensions({
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY,
   *   dimensions : new Cesium.Cartesian3(500000.0, 500000.0, 500000.0)
   * });
   * var geometry = Cesium.BoxGeometry.createGeometry(box);
   *
   * @see BoxGeometry.createGeometry
   */
  BoxGeometry.fromDimensions = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var dimensions = options.dimensions;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("dimensions", dimensions);
    Check.typeOf.number.greaterThanOrEquals("dimensions.x", dimensions.x, 0);
    Check.typeOf.number.greaterThanOrEquals("dimensions.y", dimensions.y, 0);
    Check.typeOf.number.greaterThanOrEquals("dimensions.z", dimensions.z, 0);
    //>>includeEnd('debug');

    var corner = Cartesian3.multiplyByScalar(dimensions, 0.5, new Cartesian3());

    return new BoxGeometry({
      minimum: Cartesian3.negate(corner, new Cartesian3()),
      maximum: corner,
      vertexFormat: options.vertexFormat,
      offsetAttribute: options.offsetAttribute,
    });
  };

  /**
   * Creates a cube from the dimensions of an AxisAlignedBoundingBox.
   *
   * @param {AxisAlignedBoundingBox} boundingBox A description of the AxisAlignedBoundingBox.
   * @returns {BoxGeometry}
   *
   *
   *
   * @example
   * var aabb = Cesium.AxisAlignedBoundingBox.fromPoints(Cesium.Cartesian3.fromDegreesArray([
   *      -72.0, 40.0,
   *      -70.0, 35.0,
   *      -75.0, 30.0,
   *      -70.0, 30.0,
   *      -68.0, 40.0
   * ]));
   * var box = Cesium.BoxGeometry.fromAxisAlignedBoundingBox(aabb);
   *
   * @see BoxGeometry.createGeometry
   */
  BoxGeometry.fromAxisAlignedBoundingBox = function (boundingBox) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("boundingBox", boundingBox);
    //>>includeEnd('debug');

    return new BoxGeometry({
      minimum: boundingBox.minimum,
      maximum: boundingBox.maximum,
    });
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  BoxGeometry.packedLength =
    2 * Cartesian3.packedLength + VertexFormat.packedLength + 1;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {BoxGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  BoxGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._minimum, array, startingIndex);
    Cartesian3.pack(
      value._maximum,
      array,
      startingIndex + Cartesian3.packedLength
    );
    VertexFormat.pack(
      value._vertexFormat,
      array,
      startingIndex + 2 * Cartesian3.packedLength
    );
    array[
      startingIndex + 2 * Cartesian3.packedLength + VertexFormat.packedLength
    ] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchMin = new Cartesian3();
  var scratchMax = new Cartesian3();
  var scratchVertexFormat = new VertexFormat();
  var scratchOptions = {
    minimum: scratchMin,
    maximum: scratchMax,
    vertexFormat: scratchVertexFormat,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {BoxGeometry} [result] The object into which to store the result.
   * @returns {BoxGeometry} The modified result parameter or a new BoxGeometry instance if one was not provided.
   */
  BoxGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var min = Cartesian3.unpack(array, startingIndex, scratchMin);
    var max = Cartesian3.unpack(
      array,
      startingIndex + Cartesian3.packedLength,
      scratchMax
    );
    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex + 2 * Cartesian3.packedLength,
      scratchVertexFormat
    );
    var offsetAttribute =
      array[
        startingIndex + 2 * Cartesian3.packedLength + VertexFormat.packedLength
      ];

    if (!defined(result)) {
      scratchOptions.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new BoxGeometry(scratchOptions);
    }

    result._minimum = Cartesian3.clone(min, result._minimum);
    result._maximum = Cartesian3.clone(max, result._maximum);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of a box, including its vertices, indices, and a bounding sphere.
   *
   * @param {BoxGeometry} boxGeometry A description of the box.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  BoxGeometry.createGeometry = function (boxGeometry) {
    var min = boxGeometry._minimum;
    var max = boxGeometry._maximum;
    var vertexFormat = boxGeometry._vertexFormat;

    if (Cartesian3.equals(min, max)) {
      return;
    }

    var attributes = new GeometryAttributes();
    var indices;
    var positions;

    if (
      vertexFormat.position &&
      (vertexFormat.st ||
        vertexFormat.normal ||
        vertexFormat.tangent ||
        vertexFormat.bitangent)
    ) {
      if (vertexFormat.position) {
        // 8 corner points.  Duplicated 3 times each for each incident edge/face.
        positions = new Float64Array(6 * 4 * 3);

        // +z face
        positions[0] = min.x;
        positions[1] = min.y;
        positions[2] = max.z;
        positions[3] = max.x;
        positions[4] = min.y;
        positions[5] = max.z;
        positions[6] = max.x;
        positions[7] = max.y;
        positions[8] = max.z;
        positions[9] = min.x;
        positions[10] = max.y;
        positions[11] = max.z;

        // -z face
        positions[12] = min.x;
        positions[13] = min.y;
        positions[14] = min.z;
        positions[15] = max.x;
        positions[16] = min.y;
        positions[17] = min.z;
        positions[18] = max.x;
        positions[19] = max.y;
        positions[20] = min.z;
        positions[21] = min.x;
        positions[22] = max.y;
        positions[23] = min.z;

        // +x face
        positions[24] = max.x;
        positions[25] = min.y;
        positions[26] = min.z;
        positions[27] = max.x;
        positions[28] = max.y;
        positions[29] = min.z;
        positions[30] = max.x;
        positions[31] = max.y;
        positions[32] = max.z;
        positions[33] = max.x;
        positions[34] = min.y;
        positions[35] = max.z;

        // -x face
        positions[36] = min.x;
        positions[37] = min.y;
        positions[38] = min.z;
        positions[39] = min.x;
        positions[40] = max.y;
        positions[41] = min.z;
        positions[42] = min.x;
        positions[43] = max.y;
        positions[44] = max.z;
        positions[45] = min.x;
        positions[46] = min.y;
        positions[47] = max.z;

        // +y face
        positions[48] = min.x;
        positions[49] = max.y;
        positions[50] = min.z;
        positions[51] = max.x;
        positions[52] = max.y;
        positions[53] = min.z;
        positions[54] = max.x;
        positions[55] = max.y;
        positions[56] = max.z;
        positions[57] = min.x;
        positions[58] = max.y;
        positions[59] = max.z;

        // -y face
        positions[60] = min.x;
        positions[61] = min.y;
        positions[62] = min.z;
        positions[63] = max.x;
        positions[64] = min.y;
        positions[65] = min.z;
        positions[66] = max.x;
        positions[67] = min.y;
        positions[68] = max.z;
        positions[69] = min.x;
        positions[70] = min.y;
        positions[71] = max.z;

        attributes.position = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.DOUBLE,
          componentsPerAttribute: 3,
          values: positions,
        });
      }

      if (vertexFormat.normal) {
        var normals = new Float32Array(6 * 4 * 3);

        // +z face
        normals[0] = 0.0;
        normals[1] = 0.0;
        normals[2] = 1.0;
        normals[3] = 0.0;
        normals[4] = 0.0;
        normals[5] = 1.0;
        normals[6] = 0.0;
        normals[7] = 0.0;
        normals[8] = 1.0;
        normals[9] = 0.0;
        normals[10] = 0.0;
        normals[11] = 1.0;

        // -z face
        normals[12] = 0.0;
        normals[13] = 0.0;
        normals[14] = -1.0;
        normals[15] = 0.0;
        normals[16] = 0.0;
        normals[17] = -1.0;
        normals[18] = 0.0;
        normals[19] = 0.0;
        normals[20] = -1.0;
        normals[21] = 0.0;
        normals[22] = 0.0;
        normals[23] = -1.0;

        // +x face
        normals[24] = 1.0;
        normals[25] = 0.0;
        normals[26] = 0.0;
        normals[27] = 1.0;
        normals[28] = 0.0;
        normals[29] = 0.0;
        normals[30] = 1.0;
        normals[31] = 0.0;
        normals[32] = 0.0;
        normals[33] = 1.0;
        normals[34] = 0.0;
        normals[35] = 0.0;

        // -x face
        normals[36] = -1.0;
        normals[37] = 0.0;
        normals[38] = 0.0;
        normals[39] = -1.0;
        normals[40] = 0.0;
        normals[41] = 0.0;
        normals[42] = -1.0;
        normals[43] = 0.0;
        normals[44] = 0.0;
        normals[45] = -1.0;
        normals[46] = 0.0;
        normals[47] = 0.0;

        // +y face
        normals[48] = 0.0;
        normals[49] = 1.0;
        normals[50] = 0.0;
        normals[51] = 0.0;
        normals[52] = 1.0;
        normals[53] = 0.0;
        normals[54] = 0.0;
        normals[55] = 1.0;
        normals[56] = 0.0;
        normals[57] = 0.0;
        normals[58] = 1.0;
        normals[59] = 0.0;

        // -y face
        normals[60] = 0.0;
        normals[61] = -1.0;
        normals[62] = 0.0;
        normals[63] = 0.0;
        normals[64] = -1.0;
        normals[65] = 0.0;
        normals[66] = 0.0;
        normals[67] = -1.0;
        normals[68] = 0.0;
        normals[69] = 0.0;
        normals[70] = -1.0;
        normals[71] = 0.0;

        attributes.normal = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: normals,
        });
      }

      if (vertexFormat.st) {
        var texCoords = new Float32Array(6 * 4 * 2);

        // +z face
        texCoords[0] = 0.0;
        texCoords[1] = 0.0;
        texCoords[2] = 1.0;
        texCoords[3] = 0.0;
        texCoords[4] = 1.0;
        texCoords[5] = 1.0;
        texCoords[6] = 0.0;
        texCoords[7] = 1.0;

        // -z face
        texCoords[8] = 1.0;
        texCoords[9] = 0.0;
        texCoords[10] = 0.0;
        texCoords[11] = 0.0;
        texCoords[12] = 0.0;
        texCoords[13] = 1.0;
        texCoords[14] = 1.0;
        texCoords[15] = 1.0;

        //+x face
        texCoords[16] = 0.0;
        texCoords[17] = 0.0;
        texCoords[18] = 1.0;
        texCoords[19] = 0.0;
        texCoords[20] = 1.0;
        texCoords[21] = 1.0;
        texCoords[22] = 0.0;
        texCoords[23] = 1.0;

        // -x face
        texCoords[24] = 1.0;
        texCoords[25] = 0.0;
        texCoords[26] = 0.0;
        texCoords[27] = 0.0;
        texCoords[28] = 0.0;
        texCoords[29] = 1.0;
        texCoords[30] = 1.0;
        texCoords[31] = 1.0;

        // +y face
        texCoords[32] = 1.0;
        texCoords[33] = 0.0;
        texCoords[34] = 0.0;
        texCoords[35] = 0.0;
        texCoords[36] = 0.0;
        texCoords[37] = 1.0;
        texCoords[38] = 1.0;
        texCoords[39] = 1.0;

        // -y face
        texCoords[40] = 0.0;
        texCoords[41] = 0.0;
        texCoords[42] = 1.0;
        texCoords[43] = 0.0;
        texCoords[44] = 1.0;
        texCoords[45] = 1.0;
        texCoords[46] = 0.0;
        texCoords[47] = 1.0;

        attributes.st = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 2,
          values: texCoords,
        });
      }

      if (vertexFormat.tangent) {
        var tangents = new Float32Array(6 * 4 * 3);

        // +z face
        tangents[0] = 1.0;
        tangents[1] = 0.0;
        tangents[2] = 0.0;
        tangents[3] = 1.0;
        tangents[4] = 0.0;
        tangents[5] = 0.0;
        tangents[6] = 1.0;
        tangents[7] = 0.0;
        tangents[8] = 0.0;
        tangents[9] = 1.0;
        tangents[10] = 0.0;
        tangents[11] = 0.0;

        // -z face
        tangents[12] = -1.0;
        tangents[13] = 0.0;
        tangents[14] = 0.0;
        tangents[15] = -1.0;
        tangents[16] = 0.0;
        tangents[17] = 0.0;
        tangents[18] = -1.0;
        tangents[19] = 0.0;
        tangents[20] = 0.0;
        tangents[21] = -1.0;
        tangents[22] = 0.0;
        tangents[23] = 0.0;

        // +x face
        tangents[24] = 0.0;
        tangents[25] = 1.0;
        tangents[26] = 0.0;
        tangents[27] = 0.0;
        tangents[28] = 1.0;
        tangents[29] = 0.0;
        tangents[30] = 0.0;
        tangents[31] = 1.0;
        tangents[32] = 0.0;
        tangents[33] = 0.0;
        tangents[34] = 1.0;
        tangents[35] = 0.0;

        // -x face
        tangents[36] = 0.0;
        tangents[37] = -1.0;
        tangents[38] = 0.0;
        tangents[39] = 0.0;
        tangents[40] = -1.0;
        tangents[41] = 0.0;
        tangents[42] = 0.0;
        tangents[43] = -1.0;
        tangents[44] = 0.0;
        tangents[45] = 0.0;
        tangents[46] = -1.0;
        tangents[47] = 0.0;

        // +y face
        tangents[48] = -1.0;
        tangents[49] = 0.0;
        tangents[50] = 0.0;
        tangents[51] = -1.0;
        tangents[52] = 0.0;
        tangents[53] = 0.0;
        tangents[54] = -1.0;
        tangents[55] = 0.0;
        tangents[56] = 0.0;
        tangents[57] = -1.0;
        tangents[58] = 0.0;
        tangents[59] = 0.0;

        // -y face
        tangents[60] = 1.0;
        tangents[61] = 0.0;
        tangents[62] = 0.0;
        tangents[63] = 1.0;
        tangents[64] = 0.0;
        tangents[65] = 0.0;
        tangents[66] = 1.0;
        tangents[67] = 0.0;
        tangents[68] = 0.0;
        tangents[69] = 1.0;
        tangents[70] = 0.0;
        tangents[71] = 0.0;

        attributes.tangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: tangents,
        });
      }

      if (vertexFormat.bitangent) {
        var bitangents = new Float32Array(6 * 4 * 3);

        // +z face
        bitangents[0] = 0.0;
        bitangents[1] = 1.0;
        bitangents[2] = 0.0;
        bitangents[3] = 0.0;
        bitangents[4] = 1.0;
        bitangents[5] = 0.0;
        bitangents[6] = 0.0;
        bitangents[7] = 1.0;
        bitangents[8] = 0.0;
        bitangents[9] = 0.0;
        bitangents[10] = 1.0;
        bitangents[11] = 0.0;

        // -z face
        bitangents[12] = 0.0;
        bitangents[13] = 1.0;
        bitangents[14] = 0.0;
        bitangents[15] = 0.0;
        bitangents[16] = 1.0;
        bitangents[17] = 0.0;
        bitangents[18] = 0.0;
        bitangents[19] = 1.0;
        bitangents[20] = 0.0;
        bitangents[21] = 0.0;
        bitangents[22] = 1.0;
        bitangents[23] = 0.0;

        // +x face
        bitangents[24] = 0.0;
        bitangents[25] = 0.0;
        bitangents[26] = 1.0;
        bitangents[27] = 0.0;
        bitangents[28] = 0.0;
        bitangents[29] = 1.0;
        bitangents[30] = 0.0;
        bitangents[31] = 0.0;
        bitangents[32] = 1.0;
        bitangents[33] = 0.0;
        bitangents[34] = 0.0;
        bitangents[35] = 1.0;

        // -x face
        bitangents[36] = 0.0;
        bitangents[37] = 0.0;
        bitangents[38] = 1.0;
        bitangents[39] = 0.0;
        bitangents[40] = 0.0;
        bitangents[41] = 1.0;
        bitangents[42] = 0.0;
        bitangents[43] = 0.0;
        bitangents[44] = 1.0;
        bitangents[45] = 0.0;
        bitangents[46] = 0.0;
        bitangents[47] = 1.0;

        // +y face
        bitangents[48] = 0.0;
        bitangents[49] = 0.0;
        bitangents[50] = 1.0;
        bitangents[51] = 0.0;
        bitangents[52] = 0.0;
        bitangents[53] = 1.0;
        bitangents[54] = 0.0;
        bitangents[55] = 0.0;
        bitangents[56] = 1.0;
        bitangents[57] = 0.0;
        bitangents[58] = 0.0;
        bitangents[59] = 1.0;

        // -y face
        bitangents[60] = 0.0;
        bitangents[61] = 0.0;
        bitangents[62] = 1.0;
        bitangents[63] = 0.0;
        bitangents[64] = 0.0;
        bitangents[65] = 1.0;
        bitangents[66] = 0.0;
        bitangents[67] = 0.0;
        bitangents[68] = 1.0;
        bitangents[69] = 0.0;
        bitangents[70] = 0.0;
        bitangents[71] = 1.0;

        attributes.bitangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: bitangents,
        });
      }

      // 12 triangles:  6 faces, 2 triangles each.
      indices = new Uint16Array(6 * 2 * 3);

      // +z face
      indices[0] = 0;
      indices[1] = 1;
      indices[2] = 2;
      indices[3] = 0;
      indices[4] = 2;
      indices[5] = 3;

      // -z face
      indices[6] = 4 + 2;
      indices[7] = 4 + 1;
      indices[8] = 4 + 0;
      indices[9] = 4 + 3;
      indices[10] = 4 + 2;
      indices[11] = 4 + 0;

      // +x face
      indices[12] = 8 + 0;
      indices[13] = 8 + 1;
      indices[14] = 8 + 2;
      indices[15] = 8 + 0;
      indices[16] = 8 + 2;
      indices[17] = 8 + 3;

      // -x face
      indices[18] = 12 + 2;
      indices[19] = 12 + 1;
      indices[20] = 12 + 0;
      indices[21] = 12 + 3;
      indices[22] = 12 + 2;
      indices[23] = 12 + 0;

      // +y face
      indices[24] = 16 + 2;
      indices[25] = 16 + 1;
      indices[26] = 16 + 0;
      indices[27] = 16 + 3;
      indices[28] = 16 + 2;
      indices[29] = 16 + 0;

      // -y face
      indices[30] = 20 + 0;
      indices[31] = 20 + 1;
      indices[32] = 20 + 2;
      indices[33] = 20 + 0;
      indices[34] = 20 + 2;
      indices[35] = 20 + 3;
    } else {
      // Positions only - no need to duplicate corner points
      positions = new Float64Array(8 * 3);

      positions[0] = min.x;
      positions[1] = min.y;
      positions[2] = min.z;
      positions[3] = max.x;
      positions[4] = min.y;
      positions[5] = min.z;
      positions[6] = max.x;
      positions[7] = max.y;
      positions[8] = min.z;
      positions[9] = min.x;
      positions[10] = max.y;
      positions[11] = min.z;
      positions[12] = min.x;
      positions[13] = min.y;
      positions[14] = max.z;
      positions[15] = max.x;
      positions[16] = min.y;
      positions[17] = max.z;
      positions[18] = max.x;
      positions[19] = max.y;
      positions[20] = max.z;
      positions[21] = min.x;
      positions[22] = max.y;
      positions[23] = max.z;

      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      });

      // 12 triangles:  6 faces, 2 triangles each.
      indices = new Uint16Array(6 * 2 * 3);

      // plane z = corner.Z
      indices[0] = 4;
      indices[1] = 5;
      indices[2] = 6;
      indices[3] = 4;
      indices[4] = 6;
      indices[5] = 7;

      // plane z = -corner.Z
      indices[6] = 1;
      indices[7] = 0;
      indices[8] = 3;
      indices[9] = 1;
      indices[10] = 3;
      indices[11] = 2;

      // plane x = corner.X
      indices[12] = 1;
      indices[13] = 6;
      indices[14] = 5;
      indices[15] = 1;
      indices[16] = 2;
      indices[17] = 6;

      // plane y = corner.Y
      indices[18] = 2;
      indices[19] = 3;
      indices[20] = 7;
      indices[21] = 2;
      indices[22] = 7;
      indices[23] = 6;

      // plane x = -corner.X
      indices[24] = 3;
      indices[25] = 0;
      indices[26] = 4;
      indices[27] = 3;
      indices[28] = 4;
      indices[29] = 7;

      // plane y = -corner.Y
      indices[30] = 0;
      indices[31] = 1;
      indices[32] = 5;
      indices[33] = 0;
      indices[34] = 5;
      indices[35] = 4;
    }

    var diff = Cartesian3.subtract(max, min, diffScratch);
    var radius = Cartesian3.magnitude(diff) * 0.5;

    if (defined(boxGeometry._offsetAttribute)) {
      var length = positions.length;
      var applyOffset = new Uint8Array(length / 3);
      var offsetValue =
        boxGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
      arrayFill(applyOffset, offsetValue);
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: new BoundingSphere(Cartesian3.ZERO, radius),
      offsetAttribute: boxGeometry._offsetAttribute,
    });
  };

  var unitBoxGeometry;

  /**
   * Returns the geometric representation of a unit box, including its vertices, indices, and a bounding sphere.
   * @returns {Geometry} The computed vertices and indices.
   *
   * @private
   */
  BoxGeometry.getUnitBox = function () {
    if (!defined(unitBoxGeometry)) {
      unitBoxGeometry = BoxGeometry.createGeometry(
        BoxGeometry.fromDimensions({
          dimensions: new Cartesian3(1.0, 1.0, 1.0),
          vertexFormat: VertexFormat.POSITION_ONLY,
        })
      );
    }
    return unitBoxGeometry;
  };

  var diffScratch$1 = new Cartesian3();

  /**
   * A description of the outline of a cube centered at the origin.
   *
   * @alias BoxOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.minimum The minimum x, y, and z coordinates of the box.
   * @param {Cartesian3} options.maximum The maximum x, y, and z coordinates of the box.
   *
   * @see BoxOutlineGeometry.fromDimensions
   * @see BoxOutlineGeometry.createGeometry
   * @see Packable
   *
   * @example
   * var box = new Cesium.BoxOutlineGeometry({
   *   maximum : new Cesium.Cartesian3(250000.0, 250000.0, 250000.0),
   *   minimum : new Cesium.Cartesian3(-250000.0, -250000.0, -250000.0)
   * });
   * var geometry = Cesium.BoxOutlineGeometry.createGeometry(box);
   */
  function BoxOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var min = options.minimum;
    var max = options.maximum;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("min", min);
    Check.typeOf.object("max", max);
    if (
      defined(options.offsetAttribute) &&
      options.offsetAttribute === GeometryOffsetAttribute$1.TOP
    ) {
      throw new DeveloperError(
        "GeometryOffsetAttribute.TOP is not a supported options.offsetAttribute for this geometry."
      );
    }
    //>>includeEnd('debug');

    this._min = Cartesian3.clone(min);
    this._max = Cartesian3.clone(max);
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createBoxOutlineGeometry";
  }

  /**
   * Creates an outline of a cube centered at the origin given its dimensions.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.dimensions The width, depth, and height of the box stored in the x, y, and z coordinates of the <code>Cartesian3</code>, respectively.
   * @returns {BoxOutlineGeometry}
   *
   * @exception {DeveloperError} All dimensions components must be greater than or equal to zero.
   *
   *
   * @example
   * var box = Cesium.BoxOutlineGeometry.fromDimensions({
   *   dimensions : new Cesium.Cartesian3(500000.0, 500000.0, 500000.0)
   * });
   * var geometry = Cesium.BoxOutlineGeometry.createGeometry(box);
   *
   * @see BoxOutlineGeometry.createGeometry
   */
  BoxOutlineGeometry.fromDimensions = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var dimensions = options.dimensions;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("dimensions", dimensions);
    Check.typeOf.number.greaterThanOrEquals("dimensions.x", dimensions.x, 0);
    Check.typeOf.number.greaterThanOrEquals("dimensions.y", dimensions.y, 0);
    Check.typeOf.number.greaterThanOrEquals("dimensions.z", dimensions.z, 0);
    //>>includeEnd('debug');

    var corner = Cartesian3.multiplyByScalar(dimensions, 0.5, new Cartesian3());

    return new BoxOutlineGeometry({
      minimum: Cartesian3.negate(corner, new Cartesian3()),
      maximum: corner,
      offsetAttribute: options.offsetAttribute,
    });
  };

  /**
   * Creates an outline of a cube from the dimensions of an AxisAlignedBoundingBox.
   *
   * @param {AxisAlignedBoundingBox} boundingBox A description of the AxisAlignedBoundingBox.
   * @returns {BoxOutlineGeometry}
   *
   *
   *
   * @example
   * var aabb = Cesium.AxisAlignedBoundingBox.fromPoints(Cesium.Cartesian3.fromDegreesArray([
   *      -72.0, 40.0,
   *      -70.0, 35.0,
   *      -75.0, 30.0,
   *      -70.0, 30.0,
   *      -68.0, 40.0
   * ]));
   * var box = Cesium.BoxOutlineGeometry.fromAxisAlignedBoundingBox(aabb);
   *
   *  @see BoxOutlineGeometry.createGeometry
   */
  BoxOutlineGeometry.fromAxisAlignedBoundingBox = function (boundingBox) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("boundindBox", boundingBox);
    //>>includeEnd('debug');

    return new BoxOutlineGeometry({
      minimum: boundingBox.minimum,
      maximum: boundingBox.maximum,
    });
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  BoxOutlineGeometry.packedLength = 2 * Cartesian3.packedLength + 1;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {BoxOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  BoxOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._min, array, startingIndex);
    Cartesian3.pack(value._max, array, startingIndex + Cartesian3.packedLength);
    array[startingIndex + Cartesian3.packedLength * 2] = defaultValue(
      value._offsetAttribute,
      -1
    );

    return array;
  };

  var scratchMin$1 = new Cartesian3();
  var scratchMax$1 = new Cartesian3();
  var scratchOptions$1 = {
    minimum: scratchMin$1,
    maximum: scratchMax$1,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {BoxOutlineGeometry} [result] The object into which to store the result.
   * @returns {BoxOutlineGeometry} The modified result parameter or a new BoxOutlineGeometry instance if one was not provided.
   */
  BoxOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var min = Cartesian3.unpack(array, startingIndex, scratchMin$1);
    var max = Cartesian3.unpack(
      array,
      startingIndex + Cartesian3.packedLength,
      scratchMax$1
    );
    var offsetAttribute = array[startingIndex + Cartesian3.packedLength * 2];

    if (!defined(result)) {
      scratchOptions$1.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new BoxOutlineGeometry(scratchOptions$1);
    }

    result._min = Cartesian3.clone(min, result._min);
    result._max = Cartesian3.clone(max, result._max);
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of an outline of a box, including its vertices, indices, and a bounding sphere.
   *
   * @param {BoxOutlineGeometry} boxGeometry A description of the box outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  BoxOutlineGeometry.createGeometry = function (boxGeometry) {
    var min = boxGeometry._min;
    var max = boxGeometry._max;

    if (Cartesian3.equals(min, max)) {
      return;
    }

    var attributes = new GeometryAttributes();
    var indices = new Uint16Array(12 * 2);
    var positions = new Float64Array(8 * 3);

    positions[0] = min.x;
    positions[1] = min.y;
    positions[2] = min.z;
    positions[3] = max.x;
    positions[4] = min.y;
    positions[5] = min.z;
    positions[6] = max.x;
    positions[7] = max.y;
    positions[8] = min.z;
    positions[9] = min.x;
    positions[10] = max.y;
    positions[11] = min.z;

    positions[12] = min.x;
    positions[13] = min.y;
    positions[14] = max.z;
    positions[15] = max.x;
    positions[16] = min.y;
    positions[17] = max.z;
    positions[18] = max.x;
    positions[19] = max.y;
    positions[20] = max.z;
    positions[21] = min.x;
    positions[22] = max.y;
    positions[23] = max.z;

    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: positions,
    });

    // top
    indices[0] = 4;
    indices[1] = 5;
    indices[2] = 5;
    indices[3] = 6;
    indices[4] = 6;
    indices[5] = 7;
    indices[6] = 7;
    indices[7] = 4;

    // bottom
    indices[8] = 0;
    indices[9] = 1;
    indices[10] = 1;
    indices[11] = 2;
    indices[12] = 2;
    indices[13] = 3;
    indices[14] = 3;
    indices[15] = 0;

    // left
    indices[16] = 0;
    indices[17] = 4;
    indices[18] = 1;
    indices[19] = 5;

    //right
    indices[20] = 2;
    indices[21] = 6;
    indices[22] = 3;
    indices[23] = 7;

    var diff = Cartesian3.subtract(max, min, diffScratch$1);
    var radius = Cartesian3.magnitude(diff) * 0.5;

    if (defined(boxGeometry._offsetAttribute)) {
      var length = positions.length;
      var applyOffset = new Uint8Array(length / 3);
      var offsetValue =
        boxGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
      arrayFill(applyOffset, offsetValue);
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: new BoundingSphere(Cartesian3.ZERO, radius),
      offsetAttribute: boxGeometry._offsetAttribute,
    });
  };

  /**
   * Geocodes queries containing longitude and latitude coordinates and an optional height.
   * Query format: `longitude latitude (height)` with longitude/latitude in degrees and height in meters.
   *
   * @alias CartographicGeocoderService
   * @constructor
   */
  function CartographicGeocoderService() {}

  /**
   * @function
   *
   * @param {String} query The query to be sent to the geocoder service
   * @returns {Promise<GeocoderService.Result[]>}
   */
  CartographicGeocoderService.prototype.geocode = function (query) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("query", query);
    //>>includeEnd('debug');

    var splitQuery = query.match(/[^\s,\n]+/g);
    if (splitQuery.length === 2 || splitQuery.length === 3) {
      var longitude = +splitQuery[0];
      var latitude = +splitQuery[1];
      var height = splitQuery.length === 3 ? +splitQuery[2] : 300.0;

      if (isNaN(longitude) && isNaN(latitude)) {
        var coordTest = /^(\d+.?\d*)([nsew])/i;
        for (var i = 0; i < splitQuery.length; ++i) {
          var splitCoord = splitQuery[i].match(coordTest);
          if (coordTest.test(splitQuery[i]) && splitCoord.length === 3) {
            if (/^[ns]/i.test(splitCoord[2])) {
              latitude = /^[n]/i.test(splitCoord[2])
                ? +splitCoord[1]
                : -splitCoord[1];
            } else if (/^[ew]/i.test(splitCoord[2])) {
              longitude = /^[e]/i.test(splitCoord[2])
                ? +splitCoord[1]
                : -splitCoord[1];
            }
          }
        }
      }

      if (!isNaN(longitude) && !isNaN(latitude) && !isNaN(height)) {
        var result = {
          displayName: query,
          destination: Cartesian3.fromDegrees(longitude, latitude, height),
        };
        return when.resolve([result]);
      }
    }
    return when.resolve([]);
  };

  /**
   * Creates a curve parameterized and evaluated by time. This type describes an interface
   * and is not intended to be instantiated directly.
   *
   * @alias Spline
   * @constructor
   *
   * @see CatmullRomSpline
   * @see HermiteSpline
   * @see LinearSpline
   * @see QuaternionSpline
   */
  function Spline() {
    /**
     * An array of times for the control points.
     * @type {Number[]}
     * @default undefined
     */
    this.times = undefined;

    /**
     * An array of control points.
     * @type {Cartesian3[]|Quaternion[]}
     * @default undefined
     */
    this.points = undefined;

    DeveloperError.throwInstantiationError();
  }

  /**
   * Evaluates the curve at a given time.
   * @function
   *
   * @param {Number} time The time at which to evaluate the curve.
   * @param {Cartesian3|Quaternion|Number[]} [result] The object onto which to store the result.
   * @returns {Cartesian3|Quaternion|Number[]} The modified result parameter or a new instance of the point on the curve at the given time.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  Spline.prototype.evaluate = DeveloperError.throwInstantiationError;

  /**
   * Finds an index <code>i</code> in <code>times</code> such that the parameter
   * <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
   *
   * @param {Number} time The time.
   * @param {Number} startIndex The index from which to start the search.
   * @returns {Number} The index for the element at the start of the interval.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  Spline.prototype.findTimeInterval = function (time, startIndex) {
    var times = this.times;
    var length = times.length;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    if (time < times[0] || time > times[length - 1]) {
      throw new DeveloperError("time is out of range.");
    }
    //>>includeEnd('debug');

    // Take advantage of temporal coherence by checking current, next and previous intervals
    // for containment of time.
    startIndex = defaultValue(startIndex, 0);

    if (time >= times[startIndex]) {
      if (startIndex + 1 < length && time < times[startIndex + 1]) {
        return startIndex;
      } else if (startIndex + 2 < length && time < times[startIndex + 2]) {
        return startIndex + 1;
      }
    } else if (startIndex - 1 >= 0 && time >= times[startIndex - 1]) {
      return startIndex - 1;
    }

    // The above failed so do a linear search. For the use cases so far, the
    // length of the list is less than 10. In the future, if there is a bottle neck,
    // it might be here.

    var i;
    if (time > times[startIndex]) {
      for (i = startIndex; i < length - 1; ++i) {
        if (time >= times[i] && time < times[i + 1]) {
          break;
        }
      }
    } else {
      for (i = startIndex - 1; i >= 0; --i) {
        if (time >= times[i] && time < times[i + 1]) {
          break;
        }
      }
    }

    if (i === length - 1) {
      i = length - 2;
    }

    return i;
  };

  /**
   * Wraps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, wrapped around the animation period.
   */
  Spline.prototype.wrapTime = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("time", time);
    //>>includeEnd('debug');

    var times = this.times;
    var timeEnd = times[times.length - 1];
    var timeStart = times[0];
    var timeStretch = timeEnd - timeStart;
    var divs;
    if (time < timeStart) {
      divs = Math.floor((timeStart - time) / timeStretch) + 1;
      time += divs * timeStretch;
    }
    if (time > timeEnd) {
      divs = Math.floor((time - timeEnd) / timeStretch) + 1;
      time -= divs * timeStretch;
    }
    return time;
  };

  /**
   * Clamps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, clamped to the animation period.
   */
  Spline.prototype.clampTime = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("time", time);
    //>>includeEnd('debug');

    var times = this.times;
    return CesiumMath.clamp(time, times[0], times[times.length - 1]);
  };

  /**
   * A spline that uses piecewise linear interpolation to create a curve.
   *
   * @alias LinearSpline
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times An array of strictly increasing, unit-less, floating-point times at each point.
   *                The values are in no way connected to the clock time. They are the parameterization for the curve.
   * @param {Cartesian3[]} options.points The array of {@link Cartesian3} control points.
   *
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be equal to points.length.
   *
   *
   * @example
   * var times = [ 0.0, 1.5, 3.0, 4.5, 6.0 ];
   * var spline = new Cesium.LinearSpline({
   *     times : times,
   *     points : [
   *         new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
   *         new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
   *         new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
   *         new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
   *         new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
   *     ]
   * });
   *
   * var p0 = spline.evaluate(times[0]);
   *
   * @see HermiteSpline
   * @see CatmullRomSpline
   * @see QuaternionSpline
   * @see WeightSpline
   */
  function LinearSpline(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var points = options.points;
    var times = options.times;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(points) || !defined(times)) {
      throw new DeveloperError("points and times are required.");
    }
    if (points.length < 2) {
      throw new DeveloperError(
        "points.length must be greater than or equal to 2."
      );
    }
    if (times.length !== points.length) {
      throw new DeveloperError("times.length must be equal to points.length.");
    }
    //>>includeEnd('debug');

    this._times = times;
    this._points = points;

    this._lastTimeIndex = 0;
  }

  Object.defineProperties(LinearSpline.prototype, {
    /**
     * An array of times for the control points.
     *
     * @memberof LinearSpline.prototype
     *
     * @type {Number[]}
     * @readonly
     */
    times: {
      get: function () {
        return this._times;
      },
    },

    /**
     * An array of {@link Cartesian3} control points.
     *
     * @memberof LinearSpline.prototype
     *
     * @type {Cartesian3[]}
     * @readonly
     */
    points: {
      get: function () {
        return this._points;
      },
    },
  });

  /**
   * Finds an index <code>i</code> in <code>times</code> such that the parameter
   * <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
   * @function
   *
   * @param {Number} time The time.
   * @returns {Number} The index for the element at the start of the interval.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  LinearSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;

  /**
   * Wraps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, wrapped around to the updated animation.
   */
  LinearSpline.prototype.wrapTime = Spline.prototype.wrapTime;

  /**
   * Clamps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, clamped to the animation period.
   */
  LinearSpline.prototype.clampTime = Spline.prototype.clampTime;

  /**
   * Evaluates the curve at a given time.
   *
   * @param {Number} time The time at which to evaluate the curve.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new instance of the point on the curve at the given time.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  LinearSpline.prototype.evaluate = function (time, result) {
    var points = this.points;
    var times = this.times;

    var i = (this._lastTimeIndex = this.findTimeInterval(
      time,
      this._lastTimeIndex
    ));
    var u = (time - times[i]) / (times[i + 1] - times[i]);

    if (!defined(result)) {
      result = new Cartesian3();
    }

    return Cartesian3.lerp(points[i], points[i + 1], u, result);
  };

  /**
   * Uses the Tridiagonal Matrix Algorithm, also known as the Thomas Algorithm, to solve
   * a system of linear equations where the coefficient matrix is a tridiagonal matrix.
   *
   * @namespace TridiagonalSystemSolver
   */
  var TridiagonalSystemSolver = {};

  /**
   * Solves a tridiagonal system of linear equations.
   *
   * @param {Number[]} diagonal An array with length <code>n</code> that contains the diagonal of the coefficient matrix.
   * @param {Number[]} lower An array with length <code>n - 1</code> that contains the lower diagonal of the coefficient matrix.
   * @param {Number[]} upper An array with length <code>n - 1</code> that contains the upper diagonal of the coefficient matrix.
   * @param {Cartesian3[]} right An array of Cartesians with length <code>n</code> that is the right side of the system of equations.
   *
   * @exception {DeveloperError} diagonal and right must have the same lengths.
   * @exception {DeveloperError} lower and upper must have the same lengths.
   * @exception {DeveloperError} lower and upper must be one less than the length of diagonal.
   *
   * @performance Linear time.
   *
   * @example
   * var lowerDiagonal = [1.0, 1.0, 1.0, 1.0];
   * var diagonal = [2.0, 4.0, 4.0, 4.0, 2.0];
   * var upperDiagonal = [1.0, 1.0, 1.0, 1.0];
   * var rightHandSide = [
   *     new Cesium.Cartesian3(410757.0, -1595711.0, 1375302.0),
   *     new Cesium.Cartesian3(-5986705.0, -2190640.0, 1099600.0),
   *     new Cesium.Cartesian3(-12593180.0, 288588.0, -1755549.0),
   *     new Cesium.Cartesian3(-5349898.0, 2457005.0, -2685438.0),
   *     new Cesium.Cartesian3(845820.0, 1573488.0, -1205591.0)
   * ];
   *
   * var solution = Cesium.TridiagonalSystemSolver.solve(lowerDiagonal, diagonal, upperDiagonal, rightHandSide);
   *
   * @returns {Cartesian3[]} An array of Cartesians with length <code>n</code> that is the solution to the tridiagonal system of equations.
   */
  TridiagonalSystemSolver.solve = function (lower, diagonal, upper, right) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(lower) || !(lower instanceof Array)) {
      throw new DeveloperError("The array lower is required.");
    }
    if (!defined(diagonal) || !(diagonal instanceof Array)) {
      throw new DeveloperError("The array diagonal is required.");
    }
    if (!defined(upper) || !(upper instanceof Array)) {
      throw new DeveloperError("The array upper is required.");
    }
    if (!defined(right) || !(right instanceof Array)) {
      throw new DeveloperError("The array right is required.");
    }
    if (diagonal.length !== right.length) {
      throw new DeveloperError("diagonal and right must have the same lengths.");
    }
    if (lower.length !== upper.length) {
      throw new DeveloperError("lower and upper must have the same lengths.");
    } else if (lower.length !== diagonal.length - 1) {
      throw new DeveloperError(
        "lower and upper must be one less than the length of diagonal."
      );
    }
    //>>includeEnd('debug');

    var c = new Array(upper.length);
    var d = new Array(right.length);
    var x = new Array(right.length);

    var i;
    for (i = 0; i < d.length; i++) {
      d[i] = new Cartesian3();
      x[i] = new Cartesian3();
    }

    c[0] = upper[0] / diagonal[0];
    d[0] = Cartesian3.multiplyByScalar(right[0], 1.0 / diagonal[0], d[0]);

    var scalar;
    for (i = 1; i < c.length; ++i) {
      scalar = 1.0 / (diagonal[i] - c[i - 1] * lower[i - 1]);
      c[i] = upper[i] * scalar;
      d[i] = Cartesian3.subtract(
        right[i],
        Cartesian3.multiplyByScalar(d[i - 1], lower[i - 1], d[i]),
        d[i]
      );
      d[i] = Cartesian3.multiplyByScalar(d[i], scalar, d[i]);
    }

    scalar = 1.0 / (diagonal[i] - c[i - 1] * lower[i - 1]);
    d[i] = Cartesian3.subtract(
      right[i],
      Cartesian3.multiplyByScalar(d[i - 1], lower[i - 1], d[i]),
      d[i]
    );
    d[i] = Cartesian3.multiplyByScalar(d[i], scalar, d[i]);

    x[x.length - 1] = d[d.length - 1];
    for (i = x.length - 2; i >= 0; --i) {
      x[i] = Cartesian3.subtract(
        d[i],
        Cartesian3.multiplyByScalar(x[i + 1], c[i], x[i]),
        x[i]
      );
    }

    return x;
  };

  var scratchLower = [];
  var scratchDiagonal = [];
  var scratchUpper = [];
  var scratchRight = [];

  function generateClamped(points, firstTangent, lastTangent) {
    var l = scratchLower;
    var u = scratchUpper;
    var d = scratchDiagonal;
    var r = scratchRight;

    l.length = u.length = points.length - 1;
    d.length = r.length = points.length;

    var i;
    l[0] = d[0] = 1.0;
    u[0] = 0.0;

    var right = r[0];
    if (!defined(right)) {
      right = r[0] = new Cartesian3();
    }
    Cartesian3.clone(firstTangent, right);

    for (i = 1; i < l.length - 1; ++i) {
      l[i] = u[i] = 1.0;
      d[i] = 4.0;

      right = r[i];
      if (!defined(right)) {
        right = r[i] = new Cartesian3();
      }
      Cartesian3.subtract(points[i + 1], points[i - 1], right);
      Cartesian3.multiplyByScalar(right, 3.0, right);
    }

    l[i] = 0.0;
    u[i] = 1.0;
    d[i] = 4.0;

    right = r[i];
    if (!defined(right)) {
      right = r[i] = new Cartesian3();
    }
    Cartesian3.subtract(points[i + 1], points[i - 1], right);
    Cartesian3.multiplyByScalar(right, 3.0, right);

    d[i + 1] = 1.0;
    right = r[i + 1];
    if (!defined(right)) {
      right = r[i + 1] = new Cartesian3();
    }
    Cartesian3.clone(lastTangent, right);

    return TridiagonalSystemSolver.solve(l, d, u, r);
  }

  function generateNatural(points) {
    var l = scratchLower;
    var u = scratchUpper;
    var d = scratchDiagonal;
    var r = scratchRight;

    l.length = u.length = points.length - 1;
    d.length = r.length = points.length;

    var i;
    l[0] = u[0] = 1.0;
    d[0] = 2.0;

    var right = r[0];
    if (!defined(right)) {
      right = r[0] = new Cartesian3();
    }
    Cartesian3.subtract(points[1], points[0], right);
    Cartesian3.multiplyByScalar(right, 3.0, right);

    for (i = 1; i < l.length; ++i) {
      l[i] = u[i] = 1.0;
      d[i] = 4.0;

      right = r[i];
      if (!defined(right)) {
        right = r[i] = new Cartesian3();
      }
      Cartesian3.subtract(points[i + 1], points[i - 1], right);
      Cartesian3.multiplyByScalar(right, 3.0, right);
    }

    d[i] = 2.0;

    right = r[i];
    if (!defined(right)) {
      right = r[i] = new Cartesian3();
    }
    Cartesian3.subtract(points[i], points[i - 1], right);
    Cartesian3.multiplyByScalar(right, 3.0, right);

    return TridiagonalSystemSolver.solve(l, d, u, r);
  }

  /**
   * A Hermite spline is a cubic interpolating spline. Points, incoming tangents, outgoing tangents, and times
   * must be defined for each control point. The outgoing tangents are defined for points [0, n - 2] and the incoming
   * tangents are defined for points [1, n - 1]. For example, when interpolating a segment of the curve between <code>points[i]</code> and
   * <code>points[i + 1]</code>, the tangents at the points will be <code>outTangents[i]</code> and <code>inTangents[i]</code>,
   * respectively.
   *
   * @alias HermiteSpline
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times An array of strictly increasing, unit-less, floating-point times at each point.
   *                The values are in no way connected to the clock time. They are the parameterization for the curve.
   * @param {Cartesian3[]} options.points The array of {@link Cartesian3} control points.
   * @param {Cartesian3[]} options.inTangents The array of {@link Cartesian3} incoming tangents at each control point.
   * @param {Cartesian3[]} options.outTangents The array of {@link Cartesian3} outgoing tangents at each control point.
   *
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be equal to points.length.
   * @exception {DeveloperError} inTangents and outTangents must have a length equal to points.length - 1.
   *
   *
   * @example
   * // Create a G<sup>1</sup> continuous Hermite spline
   * var times = [ 0.0, 1.5, 3.0, 4.5, 6.0 ];
   * var spline = new Cesium.HermiteSpline({
   *     times : times,
   *     points : [
   *         new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
   *         new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
   *         new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
   *         new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
   *         new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
   *     ],
   *     outTangents : [
   *         new Cesium.Cartesian3(1125196, -161816, 270551),
   *         new Cesium.Cartesian3(-996690.5, -365906.5, 184028.5),
   *         new Cesium.Cartesian3(-2096917, 48379.5, -292683.5),
   *         new Cesium.Cartesian3(-890902.5, 408999.5, -447115)
   *     ],
   *     inTangents : [
   *         new Cesium.Cartesian3(-1993381, -731813, 368057),
   *         new Cesium.Cartesian3(-4193834, 96759, -585367),
   *         new Cesium.Cartesian3(-1781805, 817999, -894230),
   *         new Cesium.Cartesian3(1165345, 112641, 47281)
   *     ]
   * });
   *
   * var p0 = spline.evaluate(times[0]);
   *
   * @see CatmullRomSpline
   * @see LinearSpline
   * @see QuaternionSpline
   * @see WeightSpline
   */
  function HermiteSpline(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var points = options.points;
    var times = options.times;
    var inTangents = options.inTangents;
    var outTangents = options.outTangents;

    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(points) ||
      !defined(times) ||
      !defined(inTangents) ||
      !defined(outTangents)
    ) {
      throw new DeveloperError(
        "times, points, inTangents, and outTangents are required."
      );
    }
    if (points.length < 2) {
      throw new DeveloperError(
        "points.length must be greater than or equal to 2."
      );
    }
    if (times.length !== points.length) {
      throw new DeveloperError("times.length must be equal to points.length.");
    }
    if (
      inTangents.length !== outTangents.length ||
      inTangents.length !== points.length - 1
    ) {
      throw new DeveloperError(
        "inTangents and outTangents must have a length equal to points.length - 1."
      );
    }
    //>>includeEnd('debug');

    this._times = times;
    this._points = points;
    this._inTangents = inTangents;
    this._outTangents = outTangents;

    this._lastTimeIndex = 0;
  }

  Object.defineProperties(HermiteSpline.prototype, {
    /**
     * An array of times for the control points.
     *
     * @memberof HermiteSpline.prototype
     *
     * @type {Number[]}
     * @readonly
     */
    times: {
      get: function () {
        return this._times;
      },
    },

    /**
     * An array of {@link Cartesian3} control points.
     *
     * @memberof HermiteSpline.prototype
     *
     * @type {Cartesian3[]}
     * @readonly
     */
    points: {
      get: function () {
        return this._points;
      },
    },

    /**
     * An array of {@link Cartesian3} incoming tangents at each control point.
     *
     * @memberof HermiteSpline.prototype
     *
     * @type {Cartesian3[]}
     * @readonly
     */
    inTangents: {
      get: function () {
        return this._inTangents;
      },
    },

    /**
     * An array of {@link Cartesian3} outgoing tangents at each control point.
     *
     * @memberof HermiteSpline.prototype
     *
     * @type {Cartesian3[]}
     * @readonly
     */
    outTangents: {
      get: function () {
        return this._outTangents;
      },
    },
  });

  /**
   * Creates a spline where the tangents at each control point are the same.
   * The curves are guaranteed to be at least in the class C<sup>1</sup>.
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times The array of control point times.
   * @param {Cartesian3[]} options.points The array of control points.
   * @param {Cartesian3[]} options.tangents The array of tangents at the control points.
   * @returns {HermiteSpline} A hermite spline.
   *
   * @exception {DeveloperError} points, times and tangents are required.
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times, points and tangents must have the same length.
   *
   * @example
   * var points = [
   *     new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
   *     new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
   *     new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
   *     new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
   *     new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
   * ];
   *
   * // Add tangents
   * var tangents = new Array(points.length);
   * tangents[0] = new Cesium.Cartesian3(1125196, -161816, 270551);
   * var temp = new Cesium.Cartesian3();
   * for (var i = 1; i < tangents.length - 1; ++i) {
   *     tangents[i] = Cesium.Cartesian3.multiplyByScalar(Cesium.Cartesian3.subtract(points[i + 1], points[i - 1], temp), 0.5, new Cesium.Cartesian3());
   * }
   * tangents[tangents.length - 1] = new Cesium.Cartesian3(1165345, 112641, 47281);
   *
   * var spline = Cesium.HermiteSpline.createC1({
   *     times : times,
   *     points : points,
   *     tangents : tangents
   * });
   */
  HermiteSpline.createC1 = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var times = options.times;
    var points = options.points;
    var tangents = options.tangents;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(points) || !defined(times) || !defined(tangents)) {
      throw new DeveloperError("points, times and tangents are required.");
    }
    if (points.length < 2) {
      throw new DeveloperError(
        "points.length must be greater than or equal to 2."
      );
    }
    if (times.length !== points.length || times.length !== tangents.length) {
      throw new DeveloperError(
        "times, points and tangents must have the same length."
      );
    }
    //>>includeEnd('debug');

    var outTangents = tangents.slice(0, tangents.length - 1);
    var inTangents = tangents.slice(1, tangents.length);

    return new HermiteSpline({
      times: times,
      points: points,
      inTangents: inTangents,
      outTangents: outTangents,
    });
  };

  /**
   * Creates a natural cubic spline. The tangents at the control points are generated
   * to create a curve in the class C<sup>2</sup>.
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times The array of control point times.
   * @param {Cartesian3[]} options.points The array of control points.
   * @returns {HermiteSpline|LinearSpline} A hermite spline or a linear spline if less than 3 control points were given.
   *
   * @exception {DeveloperError} points and times are required.
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be equal to points.length.
   *
   * @example
   * // Create a natural cubic spline above the earth from Philadelphia to Los Angeles.
   * var spline = Cesium.HermiteSpline.createNaturalCubic({
   *     times : [ 0.0, 1.5, 3.0, 4.5, 6.0 ],
   *     points : [
   *         new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
   *         new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
   *         new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
   *         new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
   *         new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
   *     ]
   * });
   */
  HermiteSpline.createNaturalCubic = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var times = options.times;
    var points = options.points;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(points) || !defined(times)) {
      throw new DeveloperError("points and times are required.");
    }
    if (points.length < 2) {
      throw new DeveloperError(
        "points.length must be greater than or equal to 2."
      );
    }
    if (times.length !== points.length) {
      throw new DeveloperError("times.length must be equal to points.length.");
    }
    //>>includeEnd('debug');

    if (points.length < 3) {
      return new LinearSpline({
        points: points,
        times: times,
      });
    }

    var tangents = generateNatural(points);
    var outTangents = tangents.slice(0, tangents.length - 1);
    var inTangents = tangents.slice(1, tangents.length);

    return new HermiteSpline({
      times: times,
      points: points,
      inTangents: inTangents,
      outTangents: outTangents,
    });
  };

  /**
   * Creates a clamped cubic spline. The tangents at the interior control points are generated
   * to create a curve in the class C<sup>2</sup>.
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times The array of control point times.
   * @param {Cartesian3[]} options.points The array of control points.
   * @param {Cartesian3} options.firstTangent The outgoing tangent of the first control point.
   * @param {Cartesian3} options.lastTangent The incoming tangent of the last control point.
   * @returns {HermiteSpline|LinearSpline} A hermite spline or a linear spline if less than 3 control points were given.
   *
   * @exception {DeveloperError} points, times, firstTangent and lastTangent are required.
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be equal to points.length.
   *
   * @example
   * // Create a clamped cubic spline above the earth from Philadelphia to Los Angeles.
   * var spline = Cesium.HermiteSpline.createClampedCubic({
   *     times : [ 0.0, 1.5, 3.0, 4.5, 6.0 ],
   *     points : [
   *         new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
   *         new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
   *         new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
   *         new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
   *         new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
   *     ],
   *     firstTangent : new Cesium.Cartesian3(1125196, -161816, 270551),
   *     lastTangent : new Cesium.Cartesian3(1165345, 112641, 47281)
   * });
   */
  HermiteSpline.createClampedCubic = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var times = options.times;
    var points = options.points;
    var firstTangent = options.firstTangent;
    var lastTangent = options.lastTangent;

    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(points) ||
      !defined(times) ||
      !defined(firstTangent) ||
      !defined(lastTangent)
    ) {
      throw new DeveloperError(
        "points, times, firstTangent and lastTangent are required."
      );
    }
    if (points.length < 2) {
      throw new DeveloperError(
        "points.length must be greater than or equal to 2."
      );
    }
    if (times.length !== points.length) {
      throw new DeveloperError("times.length must be equal to points.length.");
    }
    //>>includeEnd('debug');

    if (points.length < 3) {
      return new LinearSpline({
        points: points,
        times: times,
      });
    }

    var tangents = generateClamped(points, firstTangent, lastTangent);
    var outTangents = tangents.slice(0, tangents.length - 1);
    var inTangents = tangents.slice(1, tangents.length);

    return new HermiteSpline({
      times: times,
      points: points,
      inTangents: inTangents,
      outTangents: outTangents,
    });
  };

  HermiteSpline.hermiteCoefficientMatrix = new Matrix4(
    2.0,
    -3.0,
    0.0,
    1.0,
    -2.0,
    3.0,
    0.0,
    0.0,
    1.0,
    -2.0,
    1.0,
    0.0,
    1.0,
    -1.0,
    0.0,
    0.0
  );

  /**
   * Finds an index <code>i</code> in <code>times</code> such that the parameter
   * <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
   * @function
   *
   * @param {Number} time The time.
   * @returns {Number} The index for the element at the start of the interval.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  HermiteSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;

  var scratchTimeVec = new Cartesian4();
  var scratchTemp = new Cartesian3();

  /**
   * Wraps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, wrapped around to the updated animation.
   */
  HermiteSpline.prototype.wrapTime = Spline.prototype.wrapTime;

  /**
   * Clamps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, clamped to the animation period.
   */
  HermiteSpline.prototype.clampTime = Spline.prototype.clampTime;

  /**
   * Evaluates the curve at a given time.
   *
   * @param {Number} time The time at which to evaluate the curve.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new instance of the point on the curve at the given time.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  HermiteSpline.prototype.evaluate = function (time, result) {
    if (!defined(result)) {
      result = new Cartesian3();
    }
    var points = this.points;
    var times = this.times;
    var inTangents = this.inTangents;
    var outTangents = this.outTangents;

    var i = (this._lastTimeIndex = this.findTimeInterval(
      time,
      this._lastTimeIndex
    ));
    var u = (time - times[i]) / (times[i + 1] - times[i]);

    var timeVec = scratchTimeVec;
    timeVec.z = u;
    timeVec.y = u * u;
    timeVec.x = timeVec.y * u;
    timeVec.w = 1.0;

    var coefs = Matrix4.multiplyByVector(
      HermiteSpline.hermiteCoefficientMatrix,
      timeVec,
      timeVec
    );

    result = Cartesian3.multiplyByScalar(points[i], coefs.x, result);
    Cartesian3.multiplyByScalar(points[i + 1], coefs.y, scratchTemp);
    Cartesian3.add(result, scratchTemp, result);
    Cartesian3.multiplyByScalar(outTangents[i], coefs.z, scratchTemp);
    Cartesian3.add(result, scratchTemp, result);
    Cartesian3.multiplyByScalar(inTangents[i], coefs.w, scratchTemp);
    return Cartesian3.add(result, scratchTemp, result);
  };

  var scratchTimeVec$1 = new Cartesian4();
  var scratchTemp0 = new Cartesian3();
  var scratchTemp1 = new Cartesian3();

  function createEvaluateFunction(spline) {
    var points = spline.points;
    var times = spline.times;

    if (points.length < 3) {
      var t0 = times[0];
      var invSpan = 1.0 / (times[1] - t0);

      var p0 = points[0];
      var p1 = points[1];

      return function (time, result) {
        if (!defined(result)) {
          result = new Cartesian3();
        }
        var u = (time - t0) * invSpan;
        return Cartesian3.lerp(p0, p1, u, result);
      };
    }

    return function (time, result) {
      if (!defined(result)) {
        result = new Cartesian3();
      }
      var i = (spline._lastTimeIndex = spline.findTimeInterval(
        time,
        spline._lastTimeIndex
      ));
      var u = (time - times[i]) / (times[i + 1] - times[i]);

      var timeVec = scratchTimeVec$1;
      timeVec.z = u;
      timeVec.y = u * u;
      timeVec.x = timeVec.y * u;
      timeVec.w = 1.0;

      var p0;
      var p1;
      var p2;
      var p3;
      var coefs;

      if (i === 0) {
        p0 = points[0];
        p1 = points[1];
        p2 = spline.firstTangent;

        p3 = Cartesian3.subtract(points[2], p0, scratchTemp0);
        Cartesian3.multiplyByScalar(p3, 0.5, p3);

        coefs = Matrix4.multiplyByVector(
          HermiteSpline.hermiteCoefficientMatrix,
          timeVec,
          timeVec
        );
      } else if (i === points.length - 2) {
        p0 = points[i];
        p1 = points[i + 1];
        p3 = spline.lastTangent;

        p2 = Cartesian3.subtract(p1, points[i - 1], scratchTemp0);
        Cartesian3.multiplyByScalar(p2, 0.5, p2);

        coefs = Matrix4.multiplyByVector(
          HermiteSpline.hermiteCoefficientMatrix,
          timeVec,
          timeVec
        );
      } else {
        p0 = points[i - 1];
        p1 = points[i];
        p2 = points[i + 1];
        p3 = points[i + 2];
        coefs = Matrix4.multiplyByVector(
          CatmullRomSpline.catmullRomCoefficientMatrix,
          timeVec,
          timeVec
        );
      }
      result = Cartesian3.multiplyByScalar(p0, coefs.x, result);
      Cartesian3.multiplyByScalar(p1, coefs.y, scratchTemp1);
      Cartesian3.add(result, scratchTemp1, result);
      Cartesian3.multiplyByScalar(p2, coefs.z, scratchTemp1);
      Cartesian3.add(result, scratchTemp1, result);
      Cartesian3.multiplyByScalar(p3, coefs.w, scratchTemp1);
      return Cartesian3.add(result, scratchTemp1, result);
    };
  }

  var firstTangentScratch = new Cartesian3();
  var lastTangentScratch = new Cartesian3();

  /**
   * A Catmull-Rom spline is a cubic spline where the tangent at control points,
   * except the first and last, are computed using the previous and next control points.
   * Catmull-Rom splines are in the class C<sup>1</sup>.
   *
   * @alias CatmullRomSpline
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times An array of strictly increasing, unit-less, floating-point times at each point.
   *                The values are in no way connected to the clock time. They are the parameterization for the curve.
   * @param {Cartesian3[]} options.points The array of {@link Cartesian3} control points.
   * @param {Cartesian3} [options.firstTangent] The tangent of the curve at the first control point.
   *                     If the tangent is not given, it will be estimated.
   * @param {Cartesian3} [options.lastTangent] The tangent of the curve at the last control point.
   *                     If the tangent is not given, it will be estimated.
   *
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be equal to points.length.
   *
   *
   * @example
   * // spline above the earth from Philadelphia to Los Angeles
   * var spline = new Cesium.CatmullRomSpline({
   *     times : [ 0.0, 1.5, 3.0, 4.5, 6.0 ],
   *     points : [
   *         new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
   *         new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
   *         new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
   *         new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
   *         new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
   *     ]
   * });
   *
   * var p0 = spline.evaluate(times[i]);         // equal to positions[i]
   * var p1 = spline.evaluate(times[i] + delta); // interpolated value when delta < times[i + 1] - times[i]
   *
   * @see HermiteSpline
   * @see LinearSpline
   * @see QuaternionSpline
   * @see WeightSpline
   */
  function CatmullRomSpline(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var points = options.points;
    var times = options.times;
    var firstTangent = options.firstTangent;
    var lastTangent = options.lastTangent;

    //>>includeStart('debug', pragmas.debug);
    Check.defined("points", points);
    Check.defined("times", times);
    Check.typeOf.number.greaterThanOrEquals("points.length", points.length, 2);
    Check.typeOf.number.equals(
      "times.length",
      "points.length",
      times.length,
      points.length
    );
    //>>includeEnd('debug');

    if (points.length > 2) {
      if (!defined(firstTangent)) {
        firstTangent = firstTangentScratch;
        Cartesian3.multiplyByScalar(points[1], 2.0, firstTangent);
        Cartesian3.subtract(firstTangent, points[2], firstTangent);
        Cartesian3.subtract(firstTangent, points[0], firstTangent);
        Cartesian3.multiplyByScalar(firstTangent, 0.5, firstTangent);
      }

      if (!defined(lastTangent)) {
        var n = points.length - 1;
        lastTangent = lastTangentScratch;
        Cartesian3.multiplyByScalar(points[n - 1], 2.0, lastTangent);
        Cartesian3.subtract(points[n], lastTangent, lastTangent);
        Cartesian3.add(lastTangent, points[n - 2], lastTangent);
        Cartesian3.multiplyByScalar(lastTangent, 0.5, lastTangent);
      }
    }

    this._times = times;
    this._points = points;
    this._firstTangent = Cartesian3.clone(firstTangent);
    this._lastTangent = Cartesian3.clone(lastTangent);

    this._evaluateFunction = createEvaluateFunction(this);
    this._lastTimeIndex = 0;
  }

  Object.defineProperties(CatmullRomSpline.prototype, {
    /**
     * An array of times for the control points.
     *
     * @memberof CatmullRomSpline.prototype
     *
     * @type {Number[]}
     * @readonly
     */
    times: {
      get: function () {
        return this._times;
      },
    },

    /**
     * An array of {@link Cartesian3} control points.
     *
     * @memberof CatmullRomSpline.prototype
     *
     * @type {Cartesian3[]}
     * @readonly
     */
    points: {
      get: function () {
        return this._points;
      },
    },

    /**
     * The tangent at the first control point.
     *
     * @memberof CatmullRomSpline.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    firstTangent: {
      get: function () {
        return this._firstTangent;
      },
    },

    /**
     * The tangent at the last control point.
     *
     * @memberof CatmullRomSpline.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    lastTangent: {
      get: function () {
        return this._lastTangent;
      },
    },
  });

  /**
   * @private
   */
  CatmullRomSpline.catmullRomCoefficientMatrix = new Matrix4(
    -0.5,
    1.0,
    -0.5,
    0.0,
    1.5,
    -2.5,
    0.0,
    1.0,
    -1.5,
    2.0,
    0.5,
    0.0,
    0.5,
    -0.5,
    0.0,
    0.0
  );

  /**
   * Finds an index <code>i</code> in <code>times</code> such that the parameter
   * <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
   * @function
   *
   * @param {Number} time The time.
   * @returns {Number} The index for the element at the start of the interval.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  CatmullRomSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;

  /**
   * Wraps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, wrapped around to the updated animation.
   */
  CatmullRomSpline.prototype.wrapTime = Spline.prototype.wrapTime;

  /**
   * Clamps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, clamped to the animation period.
   */
  CatmullRomSpline.prototype.clampTime = Spline.prototype.clampTime;

  /**
   * Evaluates the curve at a given time.
   *
   * @param {Number} time The time at which to evaluate the curve.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new instance of the point on the curve at the given time.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  CatmullRomSpline.prototype.evaluate = function (time, result) {
    return this._evaluateFunction(time, result);
  };

  /**
   * @private
   */
  function getStringFromTypedArray(uint8Array, byteOffset, byteLength) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(uint8Array)) {
      throw new DeveloperError("uint8Array is required.");
    }
    if (byteOffset < 0) {
      throw new DeveloperError("byteOffset cannot be negative.");
    }
    if (byteLength < 0) {
      throw new DeveloperError("byteLength cannot be negative.");
    }
    if (byteOffset + byteLength > uint8Array.byteLength) {
      throw new DeveloperError("sub-region exceeds array bounds.");
    }
    //>>includeEnd('debug');

    byteOffset = defaultValue(byteOffset, 0);
    byteLength = defaultValue(byteLength, uint8Array.byteLength - byteOffset);

    uint8Array = uint8Array.subarray(byteOffset, byteOffset + byteLength);

    return getStringFromTypedArray.decode(uint8Array);
  }

  // Exposed functions for testing
  getStringFromTypedArray.decodeWithTextDecoder = function (view) {
    var decoder = new TextDecoder("utf-8");
    return decoder.decode(view);
  };

  getStringFromTypedArray.decodeWithFromCharCode = function (view) {
    var result = "";
    var codePoints = utf8Handler(view);
    var length = codePoints.length;
    for (var i = 0; i < length; ++i) {
      var cp = codePoints[i];
      if (cp <= 0xffff) {
        result += String.fromCharCode(cp);
      } else {
        cp -= 0x10000;
        result += String.fromCharCode((cp >> 10) + 0xd800, (cp & 0x3ff) + 0xdc00);
      }
    }
    return result;
  };

  function inRange(a, min, max) {
    return min <= a && a <= max;
  }

  // This code is inspired by public domain code found here: https://github.com/inexorabletash/text-encoding
  function utf8Handler(utfBytes) {
    var codePoint = 0;
    var bytesSeen = 0;
    var bytesNeeded = 0;
    var lowerBoundary = 0x80;
    var upperBoundary = 0xbf;

    var codePoints = [];
    var length = utfBytes.length;
    for (var i = 0; i < length; ++i) {
      var currentByte = utfBytes[i];

      // If bytesNeeded = 0, then we are starting a new character
      if (bytesNeeded === 0) {
        // 1 Byte Ascii character
        if (inRange(currentByte, 0x00, 0x7f)) {
          // Return a code point whose value is byte.
          codePoints.push(currentByte);
          continue;
        }

        // 2 Byte character
        if (inRange(currentByte, 0xc2, 0xdf)) {
          bytesNeeded = 1;
          codePoint = currentByte & 0x1f;
          continue;
        }

        // 3 Byte character
        if (inRange(currentByte, 0xe0, 0xef)) {
          // If byte is 0xE0, set utf-8 lower boundary to 0xA0.
          if (currentByte === 0xe0) {
            lowerBoundary = 0xa0;
          }
          // If byte is 0xED, set utf-8 upper boundary to 0x9F.
          if (currentByte === 0xed) {
            upperBoundary = 0x9f;
          }

          bytesNeeded = 2;
          codePoint = currentByte & 0xf;
          continue;
        }

        // 4 Byte character
        if (inRange(currentByte, 0xf0, 0xf4)) {
          // If byte is 0xF0, set utf-8 lower boundary to 0x90.
          if (currentByte === 0xf0) {
            lowerBoundary = 0x90;
          }
          // If byte is 0xF4, set utf-8 upper boundary to 0x8F.
          if (currentByte === 0xf4) {
            upperBoundary = 0x8f;
          }

          bytesNeeded = 3;
          codePoint = currentByte & 0x7;
          continue;
        }

        throw new RuntimeError("String decoding failed.");
      }

      // Out of range, so ignore the first part(s) of the character and continue with this byte on its own
      if (!inRange(currentByte, lowerBoundary, upperBoundary)) {
        codePoint = bytesNeeded = bytesSeen = 0;
        lowerBoundary = 0x80;
        upperBoundary = 0xbf;
        --i;
        continue;
      }

      // Set appropriate boundaries, since we've now checked byte 2 of a potential longer character
      lowerBoundary = 0x80;
      upperBoundary = 0xbf;

      // Add byte to code point
      codePoint = (codePoint << 6) | (currentByte & 0x3f);

      // We have the correct number of bytes, so push and reset for next character
      ++bytesSeen;
      if (bytesSeen === bytesNeeded) {
        codePoints.push(codePoint);
        codePoint = bytesNeeded = bytesSeen = 0;
      }
    }

    return codePoints;
  }

  if (typeof TextDecoder !== "undefined") {
    getStringFromTypedArray.decode =
      getStringFromTypedArray.decodeWithTextDecoder;
  } else {
    getStringFromTypedArray.decode =
      getStringFromTypedArray.decodeWithFromCharCode;
  }

  /**
   * Contains functions for operating on 2D triangles.
   *
   * @namespace Intersections2D
   */
  var Intersections2D = {};

  /**
   * Splits a 2D triangle at given axis-aligned threshold value and returns the resulting
   * polygon on a given side of the threshold.  The resulting polygon may have 0, 1, 2,
   * 3, or 4 vertices.
   *
   * @param {Number} threshold The threshold coordinate value at which to clip the triangle.
   * @param {Boolean} keepAbove true to keep the portion of the triangle above the threshold, or false
   *                            to keep the portion below.
   * @param {Number} u0 The coordinate of the first vertex in the triangle, in counter-clockwise order.
   * @param {Number} u1 The coordinate of the second vertex in the triangle, in counter-clockwise order.
   * @param {Number} u2 The coordinate of the third vertex in the triangle, in counter-clockwise order.
   * @param {Number[]} [result] The array into which to copy the result.  If this parameter is not supplied,
   *                            a new array is constructed and returned.
   * @returns {Number[]} The polygon that results after the clip, specified as a list of
   *                     vertices.  The vertices are specified in counter-clockwise order.
   *                     Each vertex is either an index from the existing list (identified as
   *                     a 0, 1, or 2) or -1 indicating a new vertex not in the original triangle.
   *                     For new vertices, the -1 is followed by three additional numbers: the
   *                     index of each of the two original vertices forming the line segment that
   *                     the new vertex lies on, and the fraction of the distance from the first
   *                     vertex to the second one.
   *
   * @example
   * var result = Cesium.Intersections2D.clipTriangleAtAxisAlignedThreshold(0.5, false, 0.2, 0.6, 0.4);
   * // result === [2, 0, -1, 1, 0, 0.25, -1, 1, 2, 0.5]
   */
  Intersections2D.clipTriangleAtAxisAlignedThreshold = function (
    threshold,
    keepAbove,
    u0,
    u1,
    u2,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(threshold)) {
      throw new DeveloperError("threshold is required.");
    }
    if (!defined(keepAbove)) {
      throw new DeveloperError("keepAbove is required.");
    }
    if (!defined(u0)) {
      throw new DeveloperError("u0 is required.");
    }
    if (!defined(u1)) {
      throw new DeveloperError("u1 is required.");
    }
    if (!defined(u2)) {
      throw new DeveloperError("u2 is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = [];
    } else {
      result.length = 0;
    }

    var u0Behind;
    var u1Behind;
    var u2Behind;
    if (keepAbove) {
      u0Behind = u0 < threshold;
      u1Behind = u1 < threshold;
      u2Behind = u2 < threshold;
    } else {
      u0Behind = u0 > threshold;
      u1Behind = u1 > threshold;
      u2Behind = u2 > threshold;
    }

    var numBehind = u0Behind + u1Behind + u2Behind;

    var u01Ratio;
    var u02Ratio;
    var u12Ratio;
    var u10Ratio;
    var u20Ratio;
    var u21Ratio;

    if (numBehind === 1) {
      if (u0Behind) {
        u01Ratio = (threshold - u0) / (u1 - u0);
        u02Ratio = (threshold - u0) / (u2 - u0);

        result.push(1);

        result.push(2);

        if (u02Ratio !== 1.0) {
          result.push(-1);
          result.push(0);
          result.push(2);
          result.push(u02Ratio);
        }

        if (u01Ratio !== 1.0) {
          result.push(-1);
          result.push(0);
          result.push(1);
          result.push(u01Ratio);
        }
      } else if (u1Behind) {
        u12Ratio = (threshold - u1) / (u2 - u1);
        u10Ratio = (threshold - u1) / (u0 - u1);

        result.push(2);

        result.push(0);

        if (u10Ratio !== 1.0) {
          result.push(-1);
          result.push(1);
          result.push(0);
          result.push(u10Ratio);
        }

        if (u12Ratio !== 1.0) {
          result.push(-1);
          result.push(1);
          result.push(2);
          result.push(u12Ratio);
        }
      } else if (u2Behind) {
        u20Ratio = (threshold - u2) / (u0 - u2);
        u21Ratio = (threshold - u2) / (u1 - u2);

        result.push(0);

        result.push(1);

        if (u21Ratio !== 1.0) {
          result.push(-1);
          result.push(2);
          result.push(1);
          result.push(u21Ratio);
        }

        if (u20Ratio !== 1.0) {
          result.push(-1);
          result.push(2);
          result.push(0);
          result.push(u20Ratio);
        }
      }
    } else if (numBehind === 2) {
      if (!u0Behind && u0 !== threshold) {
        u10Ratio = (threshold - u1) / (u0 - u1);
        u20Ratio = (threshold - u2) / (u0 - u2);

        result.push(0);

        result.push(-1);
        result.push(1);
        result.push(0);
        result.push(u10Ratio);

        result.push(-1);
        result.push(2);
        result.push(0);
        result.push(u20Ratio);
      } else if (!u1Behind && u1 !== threshold) {
        u21Ratio = (threshold - u2) / (u1 - u2);
        u01Ratio = (threshold - u0) / (u1 - u0);

        result.push(1);

        result.push(-1);
        result.push(2);
        result.push(1);
        result.push(u21Ratio);

        result.push(-1);
        result.push(0);
        result.push(1);
        result.push(u01Ratio);
      } else if (!u2Behind && u2 !== threshold) {
        u02Ratio = (threshold - u0) / (u2 - u0);
        u12Ratio = (threshold - u1) / (u2 - u1);

        result.push(2);

        result.push(-1);
        result.push(0);
        result.push(2);
        result.push(u02Ratio);

        result.push(-1);
        result.push(1);
        result.push(2);
        result.push(u12Ratio);
      }
    } else if (numBehind !== 3) {
      // Completely in front of threshold
      result.push(0);
      result.push(1);
      result.push(2);
    }
    // else Completely behind threshold

    return result;
  };

  /**
   * Compute the barycentric coordinates of a 2D position within a 2D triangle.
   *
   * @param {Number} x The x coordinate of the position for which to find the barycentric coordinates.
   * @param {Number} y The y coordinate of the position for which to find the barycentric coordinates.
   * @param {Number} x1 The x coordinate of the triangle's first vertex.
   * @param {Number} y1 The y coordinate of the triangle's first vertex.
   * @param {Number} x2 The x coordinate of the triangle's second vertex.
   * @param {Number} y2 The y coordinate of the triangle's second vertex.
   * @param {Number} x3 The x coordinate of the triangle's third vertex.
   * @param {Number} y3 The y coordinate of the triangle's third vertex.
   * @param {Cartesian3} [result] The instance into to which to copy the result.  If this parameter
   *                     is undefined, a new instance is created and returned.
   * @returns {Cartesian3} The barycentric coordinates of the position within the triangle.
   *
   * @example
   * var result = Cesium.Intersections2D.computeBarycentricCoordinates(0.0, 0.0, 0.0, 1.0, -1, -0.5, 1, -0.5);
   * // result === new Cesium.Cartesian3(1.0 / 3.0, 1.0 / 3.0, 1.0 / 3.0);
   */
  Intersections2D.computeBarycentricCoordinates = function (
    x,
    y,
    x1,
    y1,
    x2,
    y2,
    x3,
    y3,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(x)) {
      throw new DeveloperError("x is required.");
    }
    if (!defined(y)) {
      throw new DeveloperError("y is required.");
    }
    if (!defined(x1)) {
      throw new DeveloperError("x1 is required.");
    }
    if (!defined(y1)) {
      throw new DeveloperError("y1 is required.");
    }
    if (!defined(x2)) {
      throw new DeveloperError("x2 is required.");
    }
    if (!defined(y2)) {
      throw new DeveloperError("y2 is required.");
    }
    if (!defined(x3)) {
      throw new DeveloperError("x3 is required.");
    }
    if (!defined(y3)) {
      throw new DeveloperError("y3 is required.");
    }
    //>>includeEnd('debug');

    var x1mx3 = x1 - x3;
    var x3mx2 = x3 - x2;
    var y2my3 = y2 - y3;
    var y1my3 = y1 - y3;
    var inverseDeterminant = 1.0 / (y2my3 * x1mx3 + x3mx2 * y1my3);
    var ymy3 = y - y3;
    var xmx3 = x - x3;
    var l1 = (y2my3 * xmx3 + x3mx2 * ymy3) * inverseDeterminant;
    var l2 = (-y1my3 * xmx3 + x1mx3 * ymy3) * inverseDeterminant;
    var l3 = 1.0 - l1 - l2;

    if (defined(result)) {
      result.x = l1;
      result.y = l2;
      result.z = l3;
      return result;
    }
    return new Cartesian3(l1, l2, l3);
  };

  /**
   * Compute the intersection between 2 line segments
   *
   * @param {Number} x00 The x coordinate of the first line's first vertex.
   * @param {Number} y00 The y coordinate of the first line's first vertex.
   * @param {Number} x01 The x coordinate of the first line's second vertex.
   * @param {Number} y01 The y coordinate of the first line's second vertex.
   * @param {Number} x10 The x coordinate of the second line's first vertex.
   * @param {Number} y10 The y coordinate of the second line's first vertex.
   * @param {Number} x11 The x coordinate of the second line's second vertex.
   * @param {Number} y11 The y coordinate of the second line's second vertex.
   * @param {Cartesian2} [result] The instance into to which to copy the result. If this parameter
   *                     is undefined, a new instance is created and returned.
   * @returns {Cartesian2} The intersection point, undefined if there is no intersection point or lines are coincident.
   *
   * @example
   * var result = Cesium.Intersections2D.computeLineSegmentLineSegmentIntersection(0.0, 0.0, 0.0, 2.0, -1, 1, 1, 1);
   * // result === new Cesium.Cartesian2(0.0, 1.0);
   */
  Intersections2D.computeLineSegmentLineSegmentIntersection = function (
    x00,
    y00,
    x01,
    y01,
    x10,
    y10,
    x11,
    y11,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("x00", x00);
    Check.typeOf.number("y00", y00);
    Check.typeOf.number("x01", x01);
    Check.typeOf.number("y01", y01);
    Check.typeOf.number("x10", x10);
    Check.typeOf.number("y10", y10);
    Check.typeOf.number("x11", x11);
    Check.typeOf.number("y11", y11);
    //>>includeEnd('debug');

    var numerator1A = (x11 - x10) * (y00 - y10) - (y11 - y10) * (x00 - x10);
    var numerator1B = (x01 - x00) * (y00 - y10) - (y01 - y00) * (x00 - x10);
    var denominator1 = (y11 - y10) * (x01 - x00) - (x11 - x10) * (y01 - y00);

    // If denominator = 0, then lines are parallel. If denominator = 0 and both numerators are 0, then coincident
    if (denominator1 === 0) {
      return;
    }

    var ua1 = numerator1A / denominator1;
    var ub1 = numerator1B / denominator1;

    if (ua1 >= 0 && ua1 <= 1 && ub1 >= 0 && ub1 <= 1) {
      if (!defined(result)) {
        result = new Cartesian2();
      }

      result.x = x00 + ua1 * (x01 - x00);
      result.y = y00 + ua1 * (y01 - y00);

      return result;
    }
  };

  /**
   * Terrain data for a single tile where the terrain data is represented as a quantized mesh.  A quantized
   * mesh consists of three vertex attributes, longitude, latitude, and height.  All attributes are expressed
   * as 16-bit values in the range 0 to 32767.  Longitude and latitude are zero at the southwest corner
   * of the tile and 32767 at the northeast corner.  Height is zero at the minimum height in the tile
   * and 32767 at the maximum height in the tile.
   *
   * @alias QuantizedMeshTerrainData
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Uint16Array} options.quantizedVertices The buffer containing the quantized mesh.
   * @param {Uint16Array|Uint32Array} options.indices The indices specifying how the quantized vertices are linked
   *                      together into triangles.  Each three indices specifies one triangle.
   * @param {Number} options.minimumHeight The minimum terrain height within the tile, in meters above the ellipsoid.
   * @param {Number} options.maximumHeight The maximum terrain height within the tile, in meters above the ellipsoid.
   * @param {BoundingSphere} options.boundingSphere A sphere bounding all of the vertices in the mesh.
   * @param {OrientedBoundingBox} [options.orientedBoundingBox] An OrientedBoundingBox bounding all of the vertices in the mesh.
   * @param {Cartesian3} options.horizonOcclusionPoint The horizon occlusion point of the mesh.  If this point
   *                      is below the horizon, the entire tile is assumed to be below the horizon as well.
   *                      The point is expressed in ellipsoid-scaled coordinates.
   * @param {Number[]} options.westIndices The indices of the vertices on the western edge of the tile.
   * @param {Number[]} options.southIndices The indices of the vertices on the southern edge of the tile.
   * @param {Number[]} options.eastIndices The indices of the vertices on the eastern edge of the tile.
   * @param {Number[]} options.northIndices The indices of the vertices on the northern edge of the tile.
   * @param {Number} options.westSkirtHeight The height of the skirt to add on the western edge of the tile.
   * @param {Number} options.southSkirtHeight The height of the skirt to add on the southern edge of the tile.
   * @param {Number} options.eastSkirtHeight The height of the skirt to add on the eastern edge of the tile.
   * @param {Number} options.northSkirtHeight The height of the skirt to add on the northern edge of the tile.
   * @param {Number} [options.childTileMask=15] A bit mask indicating which of this tile's four children exist.
   *                 If a child's bit is set, geometry will be requested for that tile as well when it
   *                 is needed.  If the bit is cleared, the child tile is not requested and geometry is
   *                 instead upsampled from the parent.  The bit values are as follows:
   *                 <table>
   *                  <tr><th>Bit Position</th><th>Bit Value</th><th>Child Tile</th></tr>
   *                  <tr><td>0</td><td>1</td><td>Southwest</td></tr>
   *                  <tr><td>1</td><td>2</td><td>Southeast</td></tr>
   *                  <tr><td>2</td><td>4</td><td>Northwest</td></tr>
   *                  <tr><td>3</td><td>8</td><td>Northeast</td></tr>
   *                 </table>
   * @param {Boolean} [options.createdByUpsampling=false] True if this instance was created by upsampling another instance;
   *                  otherwise, false.
   * @param {Uint8Array} [options.encodedNormals] The buffer containing per vertex normals, encoded using 'oct' encoding
   * @param {Uint8Array} [options.waterMask] The buffer containing the watermask.
   * @param {Credit[]} [options.credits] Array of credits for this tile.
   *
   *
   * @example
   * var data = new Cesium.QuantizedMeshTerrainData({
   *     minimumHeight : -100,
   *     maximumHeight : 2101,
   *     quantizedVertices : new Uint16Array([// order is SW NW SE NE
   *                                          // longitude
   *                                          0, 0, 32767, 32767,
   *                                          // latitude
   *                                          0, 32767, 0, 32767,
   *                                          // heights
   *                                          16384, 0, 32767, 16384]),
   *     indices : new Uint16Array([0, 3, 1,
   *                                0, 2, 3]),
   *     boundingSphere : new Cesium.BoundingSphere(new Cesium.Cartesian3(1.0, 2.0, 3.0), 10000),
   *     orientedBoundingBox : new Cesium.OrientedBoundingBox(new Cesium.Cartesian3(1.0, 2.0, 3.0), Cesium.Matrix3.fromRotationX(Cesium.Math.PI, new Cesium.Matrix3())),
   *     horizonOcclusionPoint : new Cesium.Cartesian3(3.0, 2.0, 1.0),
   *     westIndices : [0, 1],
   *     southIndices : [0, 1],
   *     eastIndices : [2, 3],
   *     northIndices : [1, 3],
   *     westSkirtHeight : 1.0,
   *     southSkirtHeight : 1.0,
   *     eastSkirtHeight : 1.0,
   *     northSkirtHeight : 1.0
   * });
   *
   * @see TerrainData
   * @see HeightmapTerrainData
   * @see GoogleEarthEnterpriseTerrainData
   */
  function QuantizedMeshTerrainData(options) {
    //>>includeStart('debug', pragmas.debug)
    if (!defined(options) || !defined(options.quantizedVertices)) {
      throw new DeveloperError("options.quantizedVertices is required.");
    }
    if (!defined(options.indices)) {
      throw new DeveloperError("options.indices is required.");
    }
    if (!defined(options.minimumHeight)) {
      throw new DeveloperError("options.minimumHeight is required.");
    }
    if (!defined(options.maximumHeight)) {
      throw new DeveloperError("options.maximumHeight is required.");
    }
    if (!defined(options.maximumHeight)) {
      throw new DeveloperError("options.maximumHeight is required.");
    }
    if (!defined(options.boundingSphere)) {
      throw new DeveloperError("options.boundingSphere is required.");
    }
    if (!defined(options.horizonOcclusionPoint)) {
      throw new DeveloperError("options.horizonOcclusionPoint is required.");
    }
    if (!defined(options.westIndices)) {
      throw new DeveloperError("options.westIndices is required.");
    }
    if (!defined(options.southIndices)) {
      throw new DeveloperError("options.southIndices is required.");
    }
    if (!defined(options.eastIndices)) {
      throw new DeveloperError("options.eastIndices is required.");
    }
    if (!defined(options.northIndices)) {
      throw new DeveloperError("options.northIndices is required.");
    }
    if (!defined(options.westSkirtHeight)) {
      throw new DeveloperError("options.westSkirtHeight is required.");
    }
    if (!defined(options.southSkirtHeight)) {
      throw new DeveloperError("options.southSkirtHeight is required.");
    }
    if (!defined(options.eastSkirtHeight)) {
      throw new DeveloperError("options.eastSkirtHeight is required.");
    }
    if (!defined(options.northSkirtHeight)) {
      throw new DeveloperError("options.northSkirtHeight is required.");
    }
    //>>includeEnd('debug');

    this._quantizedVertices = options.quantizedVertices;
    this._encodedNormals = options.encodedNormals;
    this._indices = options.indices;
    this._minimumHeight = options.minimumHeight;
    this._maximumHeight = options.maximumHeight;
    this._boundingSphere = options.boundingSphere;
    this._orientedBoundingBox = options.orientedBoundingBox;
    this._horizonOcclusionPoint = options.horizonOcclusionPoint;
    this._credits = options.credits;

    var vertexCount = this._quantizedVertices.length / 3;
    var uValues = (this._uValues = this._quantizedVertices.subarray(
      0,
      vertexCount
    ));
    var vValues = (this._vValues = this._quantizedVertices.subarray(
      vertexCount,
      2 * vertexCount
    ));
    this._heightValues = this._quantizedVertices.subarray(
      2 * vertexCount,
      3 * vertexCount
    );

    // We don't assume that we can count on the edge vertices being sorted by u or v.
    function sortByV(a, b) {
      return vValues[a] - vValues[b];
    }

    function sortByU(a, b) {
      return uValues[a] - uValues[b];
    }

    this._westIndices = sortIndicesIfNecessary(
      options.westIndices,
      sortByV,
      vertexCount
    );
    this._southIndices = sortIndicesIfNecessary(
      options.southIndices,
      sortByU,
      vertexCount
    );
    this._eastIndices = sortIndicesIfNecessary(
      options.eastIndices,
      sortByV,
      vertexCount
    );
    this._northIndices = sortIndicesIfNecessary(
      options.northIndices,
      sortByU,
      vertexCount
    );

    this._westSkirtHeight = options.westSkirtHeight;
    this._southSkirtHeight = options.southSkirtHeight;
    this._eastSkirtHeight = options.eastSkirtHeight;
    this._northSkirtHeight = options.northSkirtHeight;

    this._childTileMask = defaultValue(options.childTileMask, 15);

    this._createdByUpsampling = defaultValue(options.createdByUpsampling, false);
    this._waterMask = options.waterMask;

    this._mesh = undefined;
  }

  Object.defineProperties(QuantizedMeshTerrainData.prototype, {
    /**
     * An array of credits for this tile.
     * @memberof QuantizedMeshTerrainData.prototype
     * @type {Credit[]}
     */
    credits: {
      get: function () {
        return this._credits;
      },
    },
    /**
     * The water mask included in this terrain data, if any.  A water mask is a rectangular
     * Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
     * Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
     * @memberof QuantizedMeshTerrainData.prototype
     * @type {Uint8Array|HTMLImageElement|HTMLCanvasElement}
     */
    waterMask: {
      get: function () {
        return this._waterMask;
      },
    },

    childTileMask: {
      get: function () {
        return this._childTileMask;
      },
    },

    canUpsample: {
      get: function () {
        return defined(this._mesh);
      },
    },
  });

  var arrayScratch = [];

  function sortIndicesIfNecessary(indices, sortFunction, vertexCount) {
    arrayScratch.length = indices.length;

    var needsSort = false;
    for (var i = 0, len = indices.length; i < len; ++i) {
      arrayScratch[i] = indices[i];
      needsSort =
        needsSort || (i > 0 && sortFunction(indices[i - 1], indices[i]) > 0);
    }

    if (needsSort) {
      arrayScratch.sort(sortFunction);
      return IndexDatatype$1.createTypedArray(vertexCount, arrayScratch);
    }
    return indices;
  }

  var createMeshTaskProcessor = new TaskProcessor(
    "createVerticesFromQuantizedTerrainMesh"
  );

  /**
   * Creates a {@link TerrainMesh} from this terrain data.
   *
   * @private
   *
   * @param {TilingScheme} tilingScheme The tiling scheme to which this tile belongs.
   * @param {Number} x The X coordinate of the tile for which to create the terrain data.
   * @param {Number} y The Y coordinate of the tile for which to create the terrain data.
   * @param {Number} level The level of the tile for which to create the terrain data.
   * @param {Number} [exaggeration=1.0] The scale used to exaggerate the terrain.
   * @returns {Promise.<TerrainMesh>|undefined} A promise for the terrain mesh, or undefined if too many
   *          asynchronous mesh creations are already in progress and the operation should
   *          be retried later.
   */
  QuantizedMeshTerrainData.prototype.createMesh = function (
    tilingScheme,
    x,
    y,
    level,
    exaggeration
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(tilingScheme)) {
      throw new DeveloperError("tilingScheme is required.");
    }
    if (!defined(x)) {
      throw new DeveloperError("x is required.");
    }
    if (!defined(y)) {
      throw new DeveloperError("y is required.");
    }
    if (!defined(level)) {
      throw new DeveloperError("level is required.");
    }
    //>>includeEnd('debug');

    var ellipsoid = tilingScheme.ellipsoid;
    var rectangle = tilingScheme.tileXYToRectangle(x, y, level);
    exaggeration = defaultValue(exaggeration, 1.0);

    var verticesPromise = createMeshTaskProcessor.scheduleTask({
      minimumHeight: this._minimumHeight,
      maximumHeight: this._maximumHeight,
      quantizedVertices: this._quantizedVertices,
      octEncodedNormals: this._encodedNormals,
      includeWebMercatorT: true,
      indices: this._indices,
      westIndices: this._westIndices,
      southIndices: this._southIndices,
      eastIndices: this._eastIndices,
      northIndices: this._northIndices,
      westSkirtHeight: this._westSkirtHeight,
      southSkirtHeight: this._southSkirtHeight,
      eastSkirtHeight: this._eastSkirtHeight,
      northSkirtHeight: this._northSkirtHeight,
      rectangle: rectangle,
      relativeToCenter: this._boundingSphere.center,
      ellipsoid: ellipsoid,
      exaggeration: exaggeration,
    });

    if (!defined(verticesPromise)) {
      // Postponed
      return undefined;
    }

    var that = this;
    return when(verticesPromise, function (result) {
      var vertexCountWithoutSkirts = that._quantizedVertices.length / 3;
      var vertexCount =
        vertexCountWithoutSkirts +
        that._westIndices.length +
        that._southIndices.length +
        that._eastIndices.length +
        that._northIndices.length;
      var indicesTypedArray = IndexDatatype$1.createTypedArray(
        vertexCount,
        result.indices
      );

      var vertices = new Float32Array(result.vertices);
      var rtc = result.center;
      var minimumHeight = result.minimumHeight;
      var maximumHeight = result.maximumHeight;
      var boundingSphere = defaultValue(
        BoundingSphere.clone(result.boundingSphere),
        that._boundingSphere
      );
      var obb = defaultValue(
        OrientedBoundingBox.clone(result.orientedBoundingBox),
        that._orientedBoundingBox
      );
      var occludeePointInScaledSpace = defaultValue(
        Cartesian3.clone(result.occludeePointInScaledSpace),
        that._horizonOcclusionPoint
      );
      var stride = result.vertexStride;
      var terrainEncoding = TerrainEncoding.clone(result.encoding);

      // Clone complex result objects because the transfer from the web worker
      // has stripped them down to JSON-style objects.
      that._mesh = new TerrainMesh(
        rtc,
        vertices,
        indicesTypedArray,
        result.indexCountWithoutSkirts,
        vertexCountWithoutSkirts,
        minimumHeight,
        maximumHeight,
        boundingSphere,
        occludeePointInScaledSpace,
        stride,
        obb,
        terrainEncoding,
        exaggeration,
        result.westIndicesSouthToNorth,
        result.southIndicesEastToWest,
        result.eastIndicesNorthToSouth,
        result.northIndicesWestToEast
      );

      // Free memory received from server after mesh is created.
      that._quantizedVertices = undefined;
      that._encodedNormals = undefined;
      that._indices = undefined;

      that._uValues = undefined;
      that._vValues = undefined;
      that._heightValues = undefined;

      that._westIndices = undefined;
      that._southIndices = undefined;
      that._eastIndices = undefined;
      that._northIndices = undefined;

      return that._mesh;
    });
  };

  var upsampleTaskProcessor = new TaskProcessor("upsampleQuantizedTerrainMesh");

  /**
   * Upsamples this terrain data for use by a descendant tile.  The resulting instance will contain a subset of the
   * vertices in this instance, interpolated if necessary.
   *
   * @param {TilingScheme} tilingScheme The tiling scheme of this terrain data.
   * @param {Number} thisX The X coordinate of this tile in the tiling scheme.
   * @param {Number} thisY The Y coordinate of this tile in the tiling scheme.
   * @param {Number} thisLevel The level of this tile in the tiling scheme.
   * @param {Number} descendantX The X coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantY The Y coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantLevel The level within the tiling scheme of the descendant tile for which we are upsampling.
   * @returns {Promise.<QuantizedMeshTerrainData>|undefined} A promise for upsampled heightmap terrain data for the descendant tile,
   *          or undefined if too many asynchronous upsample operations are in progress and the request has been
   *          deferred.
   */
  QuantizedMeshTerrainData.prototype.upsample = function (
    tilingScheme,
    thisX,
    thisY,
    thisLevel,
    descendantX,
    descendantY,
    descendantLevel
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(tilingScheme)) {
      throw new DeveloperError("tilingScheme is required.");
    }
    if (!defined(thisX)) {
      throw new DeveloperError("thisX is required.");
    }
    if (!defined(thisY)) {
      throw new DeveloperError("thisY is required.");
    }
    if (!defined(thisLevel)) {
      throw new DeveloperError("thisLevel is required.");
    }
    if (!defined(descendantX)) {
      throw new DeveloperError("descendantX is required.");
    }
    if (!defined(descendantY)) {
      throw new DeveloperError("descendantY is required.");
    }
    if (!defined(descendantLevel)) {
      throw new DeveloperError("descendantLevel is required.");
    }
    var levelDifference = descendantLevel - thisLevel;
    if (levelDifference > 1) {
      throw new DeveloperError(
        "Upsampling through more than one level at a time is not currently supported."
      );
    }
    //>>includeEnd('debug');

    var mesh = this._mesh;
    if (!defined(this._mesh)) {
      return undefined;
    }

    var isEastChild = thisX * 2 !== descendantX;
    var isNorthChild = thisY * 2 === descendantY;

    var ellipsoid = tilingScheme.ellipsoid;
    var childRectangle = tilingScheme.tileXYToRectangle(
      descendantX,
      descendantY,
      descendantLevel
    );

    var upsamplePromise = upsampleTaskProcessor.scheduleTask({
      vertices: mesh.vertices,
      vertexCountWithoutSkirts: mesh.vertexCountWithoutSkirts,
      indices: mesh.indices,
      indexCountWithoutSkirts: mesh.indexCountWithoutSkirts,
      encoding: mesh.encoding,
      minimumHeight: this._minimumHeight,
      maximumHeight: this._maximumHeight,
      isEastChild: isEastChild,
      isNorthChild: isNorthChild,
      childRectangle: childRectangle,
      ellipsoid: ellipsoid,
      exaggeration: mesh.exaggeration,
    });

    if (!defined(upsamplePromise)) {
      // Postponed
      return undefined;
    }

    var shortestSkirt = Math.min(this._westSkirtHeight, this._eastSkirtHeight);
    shortestSkirt = Math.min(shortestSkirt, this._southSkirtHeight);
    shortestSkirt = Math.min(shortestSkirt, this._northSkirtHeight);

    var westSkirtHeight = isEastChild
      ? shortestSkirt * 0.5
      : this._westSkirtHeight;
    var southSkirtHeight = isNorthChild
      ? shortestSkirt * 0.5
      : this._southSkirtHeight;
    var eastSkirtHeight = isEastChild
      ? this._eastSkirtHeight
      : shortestSkirt * 0.5;
    var northSkirtHeight = isNorthChild
      ? this._northSkirtHeight
      : shortestSkirt * 0.5;
    var credits = this._credits;

    return when(upsamplePromise).then(function (result) {
      var quantizedVertices = new Uint16Array(result.vertices);
      var indicesTypedArray = IndexDatatype$1.createTypedArray(
        quantizedVertices.length / 3,
        result.indices
      );
      var encodedNormals;
      if (defined(result.encodedNormals)) {
        encodedNormals = new Uint8Array(result.encodedNormals);
      }

      return new QuantizedMeshTerrainData({
        quantizedVertices: quantizedVertices,
        indices: indicesTypedArray,
        encodedNormals: encodedNormals,
        minimumHeight: result.minimumHeight,
        maximumHeight: result.maximumHeight,
        boundingSphere: BoundingSphere.clone(result.boundingSphere),
        orientedBoundingBox: OrientedBoundingBox.clone(
          result.orientedBoundingBox
        ),
        horizonOcclusionPoint: Cartesian3.clone(result.horizonOcclusionPoint),
        westIndices: result.westIndices,
        southIndices: result.southIndices,
        eastIndices: result.eastIndices,
        northIndices: result.northIndices,
        westSkirtHeight: westSkirtHeight,
        southSkirtHeight: southSkirtHeight,
        eastSkirtHeight: eastSkirtHeight,
        northSkirtHeight: northSkirtHeight,
        childTileMask: 0,
        credits: credits,
        createdByUpsampling: true,
      });
    });
  };

  var maxShort = 32767;
  var barycentricCoordinateScratch = new Cartesian3();

  /**
   * Computes the terrain height at a specified longitude and latitude.
   *
   * @param {Rectangle} rectangle The rectangle covered by this terrain data.
   * @param {Number} longitude The longitude in radians.
   * @param {Number} latitude The latitude in radians.
   * @returns {Number} The terrain height at the specified position.  The position is clamped to
   *          the rectangle, so expect incorrect results for positions far outside the rectangle.
   */
  QuantizedMeshTerrainData.prototype.interpolateHeight = function (
    rectangle,
    longitude,
    latitude
  ) {
    var u = CesiumMath.clamp(
      (longitude - rectangle.west) / rectangle.width,
      0.0,
      1.0
    );
    u *= maxShort;
    var v = CesiumMath.clamp(
      (latitude - rectangle.south) / rectangle.height,
      0.0,
      1.0
    );
    v *= maxShort;

    if (!defined(this._mesh)) {
      return interpolateHeight$1(this, u, v);
    }

    return interpolateMeshHeight$1(this, u, v);
  };

  function pointInBoundingBox(u, v, u0, v0, u1, v1, u2, v2) {
    var minU = Math.min(u0, u1, u2);
    var maxU = Math.max(u0, u1, u2);
    var minV = Math.min(v0, v1, v2);
    var maxV = Math.max(v0, v1, v2);
    return u >= minU && u <= maxU && v >= minV && v <= maxV;
  }

  var texCoordScratch0 = new Cartesian2();
  var texCoordScratch1 = new Cartesian2();
  var texCoordScratch2 = new Cartesian2();

  function interpolateMeshHeight$1(terrainData, u, v) {
    var mesh = terrainData._mesh;
    var vertices = mesh.vertices;
    var encoding = mesh.encoding;
    var indices = mesh.indices;

    for (var i = 0, len = indices.length; i < len; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];

      var uv0 = encoding.decodeTextureCoordinates(vertices, i0, texCoordScratch0);
      var uv1 = encoding.decodeTextureCoordinates(vertices, i1, texCoordScratch1);
      var uv2 = encoding.decodeTextureCoordinates(vertices, i2, texCoordScratch2);

      if (pointInBoundingBox(u, v, uv0.x, uv0.y, uv1.x, uv1.y, uv2.x, uv2.y)) {
        var barycentric = Intersections2D.computeBarycentricCoordinates(
          u,
          v,
          uv0.x,
          uv0.y,
          uv1.x,
          uv1.y,
          uv2.x,
          uv2.y,
          barycentricCoordinateScratch
        );
        if (
          barycentric.x >= -1e-15 &&
          barycentric.y >= -1e-15 &&
          barycentric.z >= -1e-15
        ) {
          var h0 = encoding.decodeHeight(vertices, i0);
          var h1 = encoding.decodeHeight(vertices, i1);
          var h2 = encoding.decodeHeight(vertices, i2);
          return barycentric.x * h0 + barycentric.y * h1 + barycentric.z * h2;
        }
      }
    }

    // Position does not lie in any triangle in this mesh.
    return undefined;
  }

  function interpolateHeight$1(terrainData, u, v) {
    var uBuffer = terrainData._uValues;
    var vBuffer = terrainData._vValues;
    var heightBuffer = terrainData._heightValues;

    var indices = terrainData._indices;
    for (var i = 0, len = indices.length; i < len; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];

      var u0 = uBuffer[i0];
      var u1 = uBuffer[i1];
      var u2 = uBuffer[i2];

      var v0 = vBuffer[i0];
      var v1 = vBuffer[i1];
      var v2 = vBuffer[i2];

      if (pointInBoundingBox(u, v, u0, v0, u1, v1, u2, v2)) {
        var barycentric = Intersections2D.computeBarycentricCoordinates(
          u,
          v,
          u0,
          v0,
          u1,
          v1,
          u2,
          v2,
          barycentricCoordinateScratch
        );
        if (
          barycentric.x >= -1e-15 &&
          barycentric.y >= -1e-15 &&
          barycentric.z >= -1e-15
        ) {
          var quantizedHeight =
            barycentric.x * heightBuffer[i0] +
            barycentric.y * heightBuffer[i1] +
            barycentric.z * heightBuffer[i2];
          return CesiumMath.lerp(
            terrainData._minimumHeight,
            terrainData._maximumHeight,
            quantizedHeight / maxShort
          );
        }
      }
    }

    // Position does not lie in any triangle in this mesh.
    return undefined;
  }

  /**
   * Determines if a given child tile is available, based on the
   * {@link HeightmapTerrainData.childTileMask}.  The given child tile coordinates are assumed
   * to be one of the four children of this tile.  If non-child tile coordinates are
   * given, the availability of the southeast child tile is returned.
   *
   * @param {Number} thisX The tile X coordinate of this (the parent) tile.
   * @param {Number} thisY The tile Y coordinate of this (the parent) tile.
   * @param {Number} childX The tile X coordinate of the child tile to check for availability.
   * @param {Number} childY The tile Y coordinate of the child tile to check for availability.
   * @returns {Boolean} True if the child tile is available; otherwise, false.
   */
  QuantizedMeshTerrainData.prototype.isChildAvailable = function (
    thisX,
    thisY,
    childX,
    childY
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(thisX)) {
      throw new DeveloperError("thisX is required.");
    }
    if (!defined(thisY)) {
      throw new DeveloperError("thisY is required.");
    }
    if (!defined(childX)) {
      throw new DeveloperError("childX is required.");
    }
    if (!defined(childY)) {
      throw new DeveloperError("childY is required.");
    }
    //>>includeEnd('debug');

    var bitNumber = 2; // northwest child
    if (childX !== thisX * 2) {
      ++bitNumber; // east child
    }
    if (childY !== thisY * 2) {
      bitNumber -= 2; // south child
    }

    return (this._childTileMask & (1 << bitNumber)) !== 0;
  };

  /**
   * Gets a value indicating whether or not this terrain data was created by upsampling lower resolution
   * terrain data.  If this value is false, the data was obtained from some other source, such
   * as by downloading it from a remote server.  This method should return true for instances
   * returned from a call to {@link HeightmapTerrainData#upsample}.
   *
   * @returns {Boolean} True if this instance was created by upsampling; otherwise, false.
   */
  QuantizedMeshTerrainData.prototype.wasCreatedByUpsampling = function () {
    return this._createdByUpsampling;
  };

  function LayerInformation(layer) {
    this.resource = layer.resource;
    this.version = layer.version;
    this.isHeightmap = layer.isHeightmap;
    this.tileUrlTemplates = layer.tileUrlTemplates;
    this.availability = layer.availability;
    this.hasVertexNormals = layer.hasVertexNormals;
    this.hasWaterMask = layer.hasWaterMask;
    this.hasMetadata = layer.hasMetadata;
    this.availabilityLevels = layer.availabilityLevels;
    this.availabilityTilesLoaded = layer.availabilityTilesLoaded;
    this.littleEndianExtensionSize = layer.littleEndianExtensionSize;
    this.availabilityTilesLoaded = layer.availabilityTilesLoaded;
    this.availabilityPromiseCache = {};
  }

  /**
   * A {@link TerrainProvider} that accesses terrain data in a Cesium terrain format.
   *
   * @alias CesiumTerrainProvider
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String|Promise<Resource>|Promise<String>} options.url The URL of the Cesium terrain server.
   * @param {Boolean} [options.requestVertexNormals=false] Flag that indicates if the client should request additional lighting information from the server, in the form of per vertex normals if available.
   * @param {Boolean} [options.requestWaterMask=false] Flag that indicates if the client should request per tile water masks from the server,  if available.
   * @param {Boolean} [options.requestMetadata=true] Flag that indicates if the client should request per tile metadata from the server, if available.
   * @param {Ellipsoid} [options.ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
   *
   *
   * @example
   * // Create Arctic DEM terrain with normals.
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *     terrainProvider : new Cesium.CesiumTerrainProvider({
   *         url : Cesium.IonResource.fromAssetId(3956),
   *         requestVertexNormals : true
   *     })
   * });
   *
   * @see createWorldTerrain
   * @see TerrainProvider
   */
  function CesiumTerrainProvider(options) {
    //>>includeStart('debug', pragmas.debug)
    if (!defined(options) || !defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    //>>includeEnd('debug');

    this._heightmapWidth = 65;
    this._heightmapStructure = undefined;
    this._hasWaterMask = false;
    this._hasVertexNormals = false;
    this._ellipsoid = options.ellipsoid;

    /**
     * Boolean flag that indicates if the client should request vertex normals from the server.
     * @type {Boolean}
     * @default false
     * @private
     */
    this._requestVertexNormals = defaultValue(
      options.requestVertexNormals,
      false
    );

    /**
     * Boolean flag that indicates if the client should request tile watermasks from the server.
     * @type {Boolean}
     * @default false
     * @private
     */
    this._requestWaterMask = defaultValue(options.requestWaterMask, false);

    /**
     * Boolean flag that indicates if the client should request tile metadata from the server.
     * @type {Boolean}
     * @default true
     * @private
     */
    this._requestMetadata = defaultValue(options.requestMetadata, true);

    this._errorEvent = new Event();

    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    this._availability = undefined;

    var deferred = when.defer();
    this._ready = false;
    this._readyPromise = deferred;
    this._tileCredits = undefined;

    var that = this;
    var lastResource;
    var layerJsonResource;
    var metadataError;

    var layers = (this._layers = []);
    var attribution = "";
    var overallAvailability = [];
    var overallMaxZoom = 0;
    when(options.url)
      .then(function (url) {
        var resource = Resource.createIfNeeded(url);
        resource.appendForwardSlash();
        lastResource = resource;
        layerJsonResource = lastResource.getDerivedResource({
          url: "layer.json",
        });

        // ion resources have a credits property we can use for additional attribution.
        that._tileCredits = resource.credits;

        requestLayerJson();
      })
      .otherwise(function (e) {
        deferred.reject(e);
      });

    function parseMetadataSuccess(data) {
      var message;

      if (!data.format) {
        message = "The tile format is not specified in the layer.json file.";
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestLayerJson
        );
        return;
      }

      if (!data.tiles || data.tiles.length === 0) {
        message = "The layer.json file does not specify any tile URL templates.";
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestLayerJson
        );
        return;
      }

      var hasVertexNormals = false;
      var hasWaterMask = false;
      var hasMetadata = false;
      var littleEndianExtensionSize = true;
      var isHeightmap = false;
      if (data.format === "heightmap-1.0") {
        isHeightmap = true;
        if (!defined(that._heightmapStructure)) {
          that._heightmapStructure = {
            heightScale: 1.0 / 5.0,
            heightOffset: -1000.0,
            elementsPerHeight: 1,
            stride: 1,
            elementMultiplier: 256.0,
            isBigEndian: false,
            lowestEncodedHeight: 0,
            highestEncodedHeight: 256 * 256 - 1,
          };
        }
        hasWaterMask = true;
        that._requestWaterMask = true;
      } else if (data.format.indexOf("quantized-mesh-1.") !== 0) {
        message =
          'The tile format "' + data.format + '" is invalid or not supported.';
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestLayerJson
        );
        return;
      }

      var tileUrlTemplates = data.tiles;

      var maxZoom = data.maxzoom;
      overallMaxZoom = Math.max(overallMaxZoom, maxZoom);
      // Keeps track of which of the availablity containing tiles have been loaded

      if (!data.projection || data.projection === "EPSG:4326") {
        that._tilingScheme = new GeographicTilingScheme({
          numberOfLevelZeroTilesX: 2,
          numberOfLevelZeroTilesY: 1,
          ellipsoid: that._ellipsoid,
        });
      } else if (data.projection === "EPSG:3857") {
        that._tilingScheme = new WebMercatorTilingScheme({
          numberOfLevelZeroTilesX: 1,
          numberOfLevelZeroTilesY: 1,
          ellipsoid: that._ellipsoid,
        });
      } else {
        message =
          'The projection "' + data.projection + '" is invalid or not supported.';
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestLayerJson
        );
        return;
      }

      that._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
        that._tilingScheme.ellipsoid,
        that._heightmapWidth,
        that._tilingScheme.getNumberOfXTilesAtLevel(0)
      );
      if (!data.scheme || data.scheme === "tms" || data.scheme === "slippyMap") {
        that._scheme = data.scheme;
      } else {
        message = 'The scheme "' + data.scheme + '" is invalid or not supported.';
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestLayerJson
        );
        return;
      }

      var availabilityTilesLoaded;

      // The vertex normals defined in the 'octvertexnormals' extension is identical to the original
      // contents of the original 'vertexnormals' extension.  'vertexnormals' extension is now
      // deprecated, as the extensionLength for this extension was incorrectly using big endian.
      // We maintain backwards compatibility with the legacy 'vertexnormal' implementation
      // by setting the _littleEndianExtensionSize to false. Always prefer 'octvertexnormals'
      // over 'vertexnormals' if both extensions are supported by the server.
      if (
        defined(data.extensions) &&
        data.extensions.indexOf("octvertexnormals") !== -1
      ) {
        hasVertexNormals = true;
      } else if (
        defined(data.extensions) &&
        data.extensions.indexOf("vertexnormals") !== -1
      ) {
        hasVertexNormals = true;
        littleEndianExtensionSize = false;
      }
      if (
        defined(data.extensions) &&
        data.extensions.indexOf("watermask") !== -1
      ) {
        hasWaterMask = true;
      }
      if (
        defined(data.extensions) &&
        data.extensions.indexOf("metadata") !== -1
      ) {
        hasMetadata = true;
      }

      var availabilityLevels = data.metadataAvailability;
      var availableTiles = data.available;
      var availability;
      if (defined(availableTiles) && !defined(availabilityLevels)) {
        availability = new TileAvailability(
          that._tilingScheme,
          availableTiles.length
        );
        for (var level = 0; level < availableTiles.length; ++level) {
          var rangesAtLevel = availableTiles[level];
          var yTiles = that._tilingScheme.getNumberOfYTilesAtLevel(level);
          if (!defined(overallAvailability[level])) {
            overallAvailability[level] = [];
          }

          for (
            var rangeIndex = 0;
            rangeIndex < rangesAtLevel.length;
            ++rangeIndex
          ) {
            var range = rangesAtLevel[rangeIndex];
            var yStart = yTiles - range.endY - 1;
            var yEnd = yTiles - range.startY - 1;
            overallAvailability[level].push([
              range.startX,
              yStart,
              range.endX,
              yEnd,
            ]);
            availability.addAvailableTileRange(
              level,
              range.startX,
              yStart,
              range.endX,
              yEnd
            );
          }
        }
      } else if (defined(availabilityLevels)) {
        availabilityTilesLoaded = new TileAvailability(
          that._tilingScheme,
          maxZoom
        );
        availability = new TileAvailability(that._tilingScheme, maxZoom);
        overallAvailability[0] = [[0, 0, 1, 0]];
        availability.addAvailableTileRange(0, 0, 0, 1, 0);
      }

      that._hasWaterMask = that._hasWaterMask || hasWaterMask;
      that._hasVertexNormals = that._hasVertexNormals || hasVertexNormals;
      that._hasMetadata = that._hasMetadata || hasMetadata;
      if (defined(data.attribution)) {
        if (attribution.length > 0) {
          attribution += " ";
        }
        attribution += data.attribution;
      }

      layers.push(
        new LayerInformation({
          resource: lastResource,
          version: data.version,
          isHeightmap: isHeightmap,
          tileUrlTemplates: tileUrlTemplates,
          availability: availability,
          hasVertexNormals: hasVertexNormals,
          hasWaterMask: hasWaterMask,
          hasMetadata: hasMetadata,
          availabilityLevels: availabilityLevels,
          availabilityTilesLoaded: availabilityTilesLoaded,
          littleEndianExtensionSize: littleEndianExtensionSize,
        })
      );

      var parentUrl = data.parentUrl;
      if (defined(parentUrl)) {
        if (!defined(availability)) {
          console.log(
            "A layer.json can't have a parentUrl if it does't have an available array."
          );
          return when.resolve();
        }
        lastResource = lastResource.getDerivedResource({
          url: parentUrl,
        });
        lastResource.appendForwardSlash(); // Terrain always expects a directory
        layerJsonResource = lastResource.getDerivedResource({
          url: "layer.json",
        });
        var parentMetadata = layerJsonResource.fetchJson();
        return when(parentMetadata, parseMetadataSuccess, parseMetadataFailure);
      }

      return when.resolve();
    }

    function parseMetadataFailure(data) {
      var message =
        "An error occurred while accessing " + layerJsonResource.url + ".";
      metadataError = TileProviderError.handleError(
        metadataError,
        that,
        that._errorEvent,
        message,
        undefined,
        undefined,
        undefined,
        requestLayerJson
      );
    }

    function metadataSuccess(data) {
      parseMetadataSuccess(data).then(function () {
        if (defined(metadataError)) {
          return;
        }

        var length = overallAvailability.length;
        if (length > 0) {
          var availability = (that._availability = new TileAvailability(
            that._tilingScheme,
            overallMaxZoom
          ));
          for (var level = 0; level < length; ++level) {
            var levelRanges = overallAvailability[level];
            for (var i = 0; i < levelRanges.length; ++i) {
              var range = levelRanges[i];
              availability.addAvailableTileRange(
                level,
                range[0],
                range[1],
                range[2],
                range[3]
              );
            }
          }
        }

        if (attribution.length > 0) {
          var layerJsonCredit = new Credit(attribution);

          if (defined(that._tileCredits)) {
            that._tileCredits.push(layerJsonCredit);
          } else {
            that._tileCredits = [layerJsonCredit];
          }
        }

        that._ready = true;
        that._readyPromise.resolve(true);
      });
    }

    function metadataFailure(data) {
      // If the metadata is not found, assume this is a pre-metadata heightmap tileset.
      if (defined(data) && data.statusCode === 404) {
        metadataSuccess({
          tilejson: "2.1.0",
          format: "heightmap-1.0",
          version: "1.0.0",
          scheme: "tms",
          tiles: ["{z}/{x}/{y}.terrain?v={version}"],
        });
        return;
      }
      parseMetadataFailure();
    }

    function requestLayerJson() {
      when(layerJsonResource.fetchJson())
        .then(metadataSuccess)
        .otherwise(metadataFailure);
    }
  }

  /**
   * When using the Quantized-Mesh format, a tile may be returned that includes additional extensions, such as PerVertexNormals, watermask, etc.
   * This enumeration defines the unique identifiers for each type of extension data that has been appended to the standard mesh data.
   *
   * @namespace QuantizedMeshExtensionIds
   * @see CesiumTerrainProvider
   * @private
   */
  var QuantizedMeshExtensionIds = {
    /**
     * Oct-Encoded Per-Vertex Normals are included as an extension to the tile mesh
     *
     * @type {Number}
     * @constant
     * @default 1
     */
    OCT_VERTEX_NORMALS: 1,
    /**
     * A watermask is included as an extension to the tile mesh
     *
     * @type {Number}
     * @constant
     * @default 2
     */
    WATER_MASK: 2,
    /**
     * A json object contain metadata about the tile
     *
     * @type {Number}
     * @constant
     * @default 4
     */
    METADATA: 4,
  };

  function getRequestHeader(extensionsList) {
    if (!defined(extensionsList) || extensionsList.length === 0) {
      return {
        Accept:
          "application/vnd.quantized-mesh,application/octet-stream;q=0.9,*/*;q=0.01",
      };
    }
    var extensions = extensionsList.join("-");
    return {
      Accept:
        "application/vnd.quantized-mesh;extensions=" +
        extensions +
        ",application/octet-stream;q=0.9,*/*;q=0.01",
    };
  }

  function createHeightmapTerrainData(provider, buffer, level, x, y) {
    var heightBuffer = new Uint16Array(
      buffer,
      0,
      provider._heightmapWidth * provider._heightmapWidth
    );
    return new HeightmapTerrainData({
      buffer: heightBuffer,
      childTileMask: new Uint8Array(buffer, heightBuffer.byteLength, 1)[0],
      waterMask: new Uint8Array(
        buffer,
        heightBuffer.byteLength + 1,
        buffer.byteLength - heightBuffer.byteLength - 1
      ),
      width: provider._heightmapWidth,
      height: provider._heightmapWidth,
      structure: provider._heightmapStructure,
      credits: provider._tileCredits,
    });
  }

  function createQuantizedMeshTerrainData(provider, buffer, level, x, y, layer) {
    var littleEndianExtensionSize = layer.littleEndianExtensionSize;
    var pos = 0;
    var cartesian3Elements = 3;
    var boundingSphereElements = cartesian3Elements + 1;
    var cartesian3Length = Float64Array.BYTES_PER_ELEMENT * cartesian3Elements;
    var boundingSphereLength =
      Float64Array.BYTES_PER_ELEMENT * boundingSphereElements;
    var encodedVertexElements = 3;
    var encodedVertexLength =
      Uint16Array.BYTES_PER_ELEMENT * encodedVertexElements;
    var triangleElements = 3;
    var bytesPerIndex = Uint16Array.BYTES_PER_ELEMENT;
    var triangleLength = bytesPerIndex * triangleElements;

    var view = new DataView(buffer);
    var center = new Cartesian3(
      view.getFloat64(pos, true),
      view.getFloat64(pos + 8, true),
      view.getFloat64(pos + 16, true)
    );
    pos += cartesian3Length;

    var minimumHeight = view.getFloat32(pos, true);
    pos += Float32Array.BYTES_PER_ELEMENT;
    var maximumHeight = view.getFloat32(pos, true);
    pos += Float32Array.BYTES_PER_ELEMENT;

    var boundingSphere = new BoundingSphere(
      new Cartesian3(
        view.getFloat64(pos, true),
        view.getFloat64(pos + 8, true),
        view.getFloat64(pos + 16, true)
      ),
      view.getFloat64(pos + cartesian3Length, true)
    );
    pos += boundingSphereLength;

    var horizonOcclusionPoint = new Cartesian3(
      view.getFloat64(pos, true),
      view.getFloat64(pos + 8, true),
      view.getFloat64(pos + 16, true)
    );
    pos += cartesian3Length;

    var vertexCount = view.getUint32(pos, true);
    pos += Uint32Array.BYTES_PER_ELEMENT;
    var encodedVertexBuffer = new Uint16Array(buffer, pos, vertexCount * 3);
    pos += vertexCount * encodedVertexLength;

    if (vertexCount > 64 * 1024) {
      // More than 64k vertices, so indices are 32-bit.
      bytesPerIndex = Uint32Array.BYTES_PER_ELEMENT;
      triangleLength = bytesPerIndex * triangleElements;
    }

    // Decode the vertex buffer.
    var uBuffer = encodedVertexBuffer.subarray(0, vertexCount);
    var vBuffer = encodedVertexBuffer.subarray(vertexCount, 2 * vertexCount);
    var heightBuffer = encodedVertexBuffer.subarray(
      vertexCount * 2,
      3 * vertexCount
    );

    AttributeCompression.zigZagDeltaDecode(uBuffer, vBuffer, heightBuffer);

    // skip over any additional padding that was added for 2/4 byte alignment
    if (pos % bytesPerIndex !== 0) {
      pos += bytesPerIndex - (pos % bytesPerIndex);
    }

    var triangleCount = view.getUint32(pos, true);
    pos += Uint32Array.BYTES_PER_ELEMENT;
    var indices = IndexDatatype$1.createTypedArrayFromArrayBuffer(
      vertexCount,
      buffer,
      pos,
      triangleCount * triangleElements
    );
    pos += triangleCount * triangleLength;

    // High water mark decoding based on decompressIndices_ in webgl-loader's loader.js.
    // https://code.google.com/p/webgl-loader/source/browse/trunk/samples/loader.js?r=99#55
    // Copyright 2012 Google Inc., Apache 2.0 license.
    var highest = 0;
    var length = indices.length;
    for (var i = 0; i < length; ++i) {
      var code = indices[i];
      indices[i] = highest - code;
      if (code === 0) {
        ++highest;
      }
    }

    var westVertexCount = view.getUint32(pos, true);
    pos += Uint32Array.BYTES_PER_ELEMENT;
    var westIndices = IndexDatatype$1.createTypedArrayFromArrayBuffer(
      vertexCount,
      buffer,
      pos,
      westVertexCount
    );
    pos += westVertexCount * bytesPerIndex;

    var southVertexCount = view.getUint32(pos, true);
    pos += Uint32Array.BYTES_PER_ELEMENT;
    var southIndices = IndexDatatype$1.createTypedArrayFromArrayBuffer(
      vertexCount,
      buffer,
      pos,
      southVertexCount
    );
    pos += southVertexCount * bytesPerIndex;

    var eastVertexCount = view.getUint32(pos, true);
    pos += Uint32Array.BYTES_PER_ELEMENT;
    var eastIndices = IndexDatatype$1.createTypedArrayFromArrayBuffer(
      vertexCount,
      buffer,
      pos,
      eastVertexCount
    );
    pos += eastVertexCount * bytesPerIndex;

    var northVertexCount = view.getUint32(pos, true);
    pos += Uint32Array.BYTES_PER_ELEMENT;
    var northIndices = IndexDatatype$1.createTypedArrayFromArrayBuffer(
      vertexCount,
      buffer,
      pos,
      northVertexCount
    );
    pos += northVertexCount * bytesPerIndex;

    var encodedNormalBuffer;
    var waterMaskBuffer;
    while (pos < view.byteLength) {
      var extensionId = view.getUint8(pos, true);
      pos += Uint8Array.BYTES_PER_ELEMENT;
      var extensionLength = view.getUint32(pos, littleEndianExtensionSize);
      pos += Uint32Array.BYTES_PER_ELEMENT;

      if (
        extensionId === QuantizedMeshExtensionIds.OCT_VERTEX_NORMALS &&
        provider._requestVertexNormals
      ) {
        encodedNormalBuffer = new Uint8Array(buffer, pos, vertexCount * 2);
      } else if (
        extensionId === QuantizedMeshExtensionIds.WATER_MASK &&
        provider._requestWaterMask
      ) {
        waterMaskBuffer = new Uint8Array(buffer, pos, extensionLength);
      } else if (
        extensionId === QuantizedMeshExtensionIds.METADATA &&
        provider._requestMetadata
      ) {
        var stringLength = view.getUint32(pos, true);
        if (stringLength > 0) {
          var jsonString = getStringFromTypedArray(
            new Uint8Array(buffer),
            pos + Uint32Array.BYTES_PER_ELEMENT,
            stringLength
          );
          var metadata = JSON.parse(jsonString);
          var availableTiles = metadata.available;
          if (defined(availableTiles)) {
            for (var offset = 0; offset < availableTiles.length; ++offset) {
              var availableLevel = level + offset + 1;
              var rangesAtLevel = availableTiles[offset];
              var yTiles = provider._tilingScheme.getNumberOfYTilesAtLevel(
                availableLevel
              );

              for (
                var rangeIndex = 0;
                rangeIndex < rangesAtLevel.length;
                ++rangeIndex
              ) {
                var range = rangesAtLevel[rangeIndex];
                var yStart = yTiles - range.endY - 1;
                var yEnd = yTiles - range.startY - 1;
                provider.availability.addAvailableTileRange(
                  availableLevel,
                  range.startX,
                  yStart,
                  range.endX,
                  yEnd
                );
                layer.availability.addAvailableTileRange(
                  availableLevel,
                  range.startX,
                  yStart,
                  range.endX,
                  yEnd
                );
              }
            }
          }
        }
        layer.availabilityTilesLoaded.addAvailableTileRange(level, x, y, x, y);
      }
      pos += extensionLength;
    }

    var skirtHeight = provider.getLevelMaximumGeometricError(level) * 5.0;

    // The skirt is not included in the OBB computation. If this ever
    // causes any rendering artifacts (cracks), they are expected to be
    // minor and in the corners of the screen. It's possible that this
    // might need to be changed - just change to `minimumHeight - skirtHeight`
    // A similar change might also be needed in `upsampleQuantizedTerrainMesh.js`.
    var rectangle = provider._tilingScheme.tileXYToRectangle(x, y, level);
    var orientedBoundingBox = OrientedBoundingBox.fromRectangle(
      rectangle,
      minimumHeight,
      maximumHeight,
      provider._tilingScheme.ellipsoid
    );

    return new QuantizedMeshTerrainData({
      center: center,
      minimumHeight: minimumHeight,
      maximumHeight: maximumHeight,
      boundingSphere: boundingSphere,
      orientedBoundingBox: orientedBoundingBox,
      horizonOcclusionPoint: horizonOcclusionPoint,
      quantizedVertices: encodedVertexBuffer,
      encodedNormals: encodedNormalBuffer,
      indices: indices,
      westIndices: westIndices,
      southIndices: southIndices,
      eastIndices: eastIndices,
      northIndices: northIndices,
      westSkirtHeight: skirtHeight,
      southSkirtHeight: skirtHeight,
      eastSkirtHeight: skirtHeight,
      northSkirtHeight: skirtHeight,
      childTileMask: provider.availability.computeChildMaskForTile(level, x, y),
      waterMask: waterMaskBuffer,
      credits: provider._tileCredits,
    });
  }

  /**
   * Requests the geometry for a given tile.  This function should not be called before
   * {@link CesiumTerrainProvider#ready} returns true.  The result must include terrain data and
   * may optionally include a water mask and an indication of which child tiles are available.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @param {Request} [request] The request object. Intended for internal use only.
   *
   * @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry.  If this method
   *          returns undefined instead of a promise, it is an indication that too many requests are already
   *          pending and the request will be retried later.
   *
   * @exception {DeveloperError} This function must not be called before {@link CesiumTerrainProvider#ready}
   *            returns true.
   */
  CesiumTerrainProvider.prototype.requestTileGeometry = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug)
    if (!this._ready) {
      throw new DeveloperError(
        "requestTileGeometry must not be called before the terrain provider is ready."
      );
    }
    //>>includeEnd('debug');

    var layers = this._layers;
    var layerToUse;
    var layerCount = layers.length;

    if (layerCount === 1) {
      // Optimized path for single layers
      layerToUse = layers[0];
    } else {
      for (var i = 0; i < layerCount; ++i) {
        var layer = layers[i];
        if (
          !defined(layer.availability) ||
          layer.availability.isTileAvailable(level, x, y)
        ) {
          layerToUse = layer;
          break;
        }
      }
    }

    return requestTileGeometry(this, x, y, level, layerToUse, request);
  };

  function requestTileGeometry(provider, x, y, level, layerToUse, request) {
    if (!defined(layerToUse)) {
      return when.reject(new RuntimeError("Terrain tile doesn't exist"));
    }

    var urlTemplates = layerToUse.tileUrlTemplates;
    if (urlTemplates.length === 0) {
      return undefined;
    }

    // The TileMapService scheme counts from the bottom left
    var terrainY;
    if (!provider._scheme || provider._scheme === "tms") {
      var yTiles = provider._tilingScheme.getNumberOfYTilesAtLevel(level);
      terrainY = yTiles - y - 1;
    } else {
      terrainY = y;
    }

    var extensionList = [];
    if (provider._requestVertexNormals && layerToUse.hasVertexNormals) {
      extensionList.push(
        layerToUse.littleEndianExtensionSize
          ? "octvertexnormals"
          : "vertexnormals"
      );
    }
    if (provider._requestWaterMask && layerToUse.hasWaterMask) {
      extensionList.push("watermask");
    }
    if (provider._requestMetadata && layerToUse.hasMetadata) {
      extensionList.push("metadata");
    }

    var headers;
    var query;
    var url = urlTemplates[(x + terrainY + level) % urlTemplates.length];

    var resource = layerToUse.resource;
    if (
      defined(resource._ionEndpoint) &&
      !defined(resource._ionEndpoint.externalType)
    ) {
      // ion uses query paremeters to request extensions
      if (extensionList.length !== 0) {
        query = { extensions: extensionList.join("-") };
      }
      headers = getRequestHeader(undefined);
    } else {
      //All other terrain servers
      headers = getRequestHeader(extensionList);
    }

    var promise = resource
      .getDerivedResource({
        url: url,
        templateValues: {
          version: layerToUse.version,
          z: level,
          x: x,
          y: terrainY,
        },
        queryParameters: query,
        headers: headers,
        request: request,
      })
      .fetchArrayBuffer();

    if (!defined(promise)) {
      return undefined;
    }

    return promise.then(function (buffer) {
      if (defined(provider._heightmapStructure)) {
        return createHeightmapTerrainData(provider, buffer);
      }
      return createQuantizedMeshTerrainData(
        provider,
        buffer,
        level,
        x,
        y,
        layerToUse
      );
    });
  }

  Object.defineProperties(CesiumTerrainProvider.prototype, {
    /**
     * Gets an event that is raised when the terrain provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets the credit to display when this terrain provider is active.  Typically this is used to credit
     * the source of the terrain.  This function should not be called before {@link CesiumTerrainProvider#ready} returns true.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        //>>includeStart('debug', pragmas.debug)
        if (!this._ready) {
          throw new DeveloperError(
            "credit must not be called before the terrain provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._credit;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link CesiumTerrainProvider#ready} returns true.
     * @memberof CesiumTerrainProvider.prototype
     * @type {GeographicTilingScheme}
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug)
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the terrain provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Gets a value indicating whether or not the provider includes a water mask.  The water mask
     * indicates which areas of the globe are water rather than land, so they can be rendered
     * as a reflective surface with animated waves.  This function should not be
     * called before {@link CesiumTerrainProvider#ready} returns true.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     * @exception {DeveloperError} This property must not be called before {@link CesiumTerrainProvider#ready}
     */
    hasWaterMask: {
      get: function () {
        //>>includeStart('debug', pragmas.debug)
        if (!this._ready) {
          throw new DeveloperError(
            "hasWaterMask must not be called before the terrain provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._hasWaterMask && this._requestWaterMask;
      },
    },

    /**
     * Gets a value indicating whether or not the requested tiles include vertex normals.
     * This function should not be called before {@link CesiumTerrainProvider#ready} returns true.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     * @exception {DeveloperError} This property must not be called before {@link CesiumTerrainProvider#ready}
     */
    hasVertexNormals: {
      get: function () {
        //>>includeStart('debug', pragmas.debug)
        if (!this._ready) {
          throw new DeveloperError(
            "hasVertexNormals must not be called before the terrain provider is ready."
          );
        }
        //>>includeEnd('debug');

        // returns true if we can request vertex normals from the server
        return this._hasVertexNormals && this._requestVertexNormals;
      },
    },

    /**
     * Gets a value indicating whether or not the requested tiles include metadata.
     * This function should not be called before {@link CesiumTerrainProvider#ready} returns true.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     * @exception {DeveloperError} This property must not be called before {@link CesiumTerrainProvider#ready}
     */
    hasMetadata: {
      get: function () {
        //>>includeStart('debug', pragmas.debug)
        if (!this._ready) {
          throw new DeveloperError(
            "hasMetadata must not be called before the terrain provider is ready."
          );
        }
        //>>includeEnd('debug');

        // returns true if we can request metadata from the server
        return this._hasMetadata && this._requestMetadata;
      },
    },

    /**
     * Boolean flag that indicates if the client should request vertex normals from the server.
     * Vertex normals data is appended to the standard tile mesh data only if the client requests the vertex normals and
     * if the server provides vertex normals.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     */
    requestVertexNormals: {
      get: function () {
        return this._requestVertexNormals;
      },
    },

    /**
     * Boolean flag that indicates if the client should request a watermask from the server.
     * Watermask data is appended to the standard tile mesh data only if the client requests the watermask and
     * if the server provides a watermask.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     */
    requestWaterMask: {
      get: function () {
        return this._requestWaterMask;
      },
    },

    /**
     * Boolean flag that indicates if the client should request metadata from the server.
     * Metadata is appended to the standard tile mesh data only if the client requests the metadata and
     * if the server provides a metadata.
     * @memberof CesiumTerrainProvider.prototype
     * @type {Boolean}
     */
    requestMetadata: {
      get: function () {
        return this._requestMetadata;
      },
    },

    /**
     * Gets an object that can be used to determine availability of terrain from this provider, such as
     * at points and in rectangles.  This function should not be called before
     * {@link CesiumTerrainProvider#ready} returns true.  This property may be undefined if availability
     * information is not available. Note that this reflects tiles that are known to be available currently.
     * Additional tiles may be discovered to be available in the future, e.g. if availability information
     * exists deeper in the tree rather than it all being discoverable at the root. However, a tile that
     * is available now will not become unavailable in the future.
     * @memberof CesiumTerrainProvider.prototype
     * @type {TileAvailability}
     */
    availability: {
      get: function () {
        //>>includeStart('debug', pragmas.debug)
        if (!this._ready) {
          throw new DeveloperError(
            "availability must not be called before the terrain provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._availability;
      },
    },
  });

  /**
   * Gets the maximum geometric error allowed in a tile at a given level.
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error.
   */
  CesiumTerrainProvider.prototype.getLevelMaximumGeometricError = function (
    level
  ) {
    return this._levelZeroMaximumGeometricError / (1 << level);
  };

  /**
   * Determines whether data for a tile is available to be loaded.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {Boolean} Undefined if not supported or availability is unknown, otherwise true or false.
   */
  CesiumTerrainProvider.prototype.getTileDataAvailable = function (x, y, level) {
    if (!defined(this._availability)) {
      return undefined;
    }
    if (level > this._availability._maximumLevel) {
      return false;
    }

    if (this._availability.isTileAvailable(level, x, y)) {
      // If the tile is listed as available, then we are done
      return true;
    }
    if (!this._hasMetadata) {
      // If we don't have any layers with the metadata extension then we don't have this tile
      return false;
    }

    var layers = this._layers;
    var count = layers.length;
    for (var i = 0; i < count; ++i) {
      var layerResult = checkLayer(this, x, y, level, layers[i], i === 0);
      if (layerResult.result) {
        // There is a layer that may or may not have the tile
        return undefined;
      }
    }

    return false;
  };

  /**
   * Makes sure we load availability data for a tile
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {undefined|Promise<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
   */
  CesiumTerrainProvider.prototype.loadTileDataAvailability = function (
    x,
    y,
    level
  ) {
    if (
      !defined(this._availability) ||
      level > this._availability._maximumLevel ||
      this._availability.isTileAvailable(level, x, y) ||
      !this._hasMetadata
    ) {
      // We know the tile is either available or not available so nothing to wait on
      return undefined;
    }

    var layers = this._layers;
    var count = layers.length;
    for (var i = 0; i < count; ++i) {
      var layerResult = checkLayer(this, x, y, level, layers[i], i === 0);
      if (defined(layerResult.promise)) {
        return layerResult.promise;
      }
    }
  };

  function getAvailabilityTile(layer, x, y, level) {
    if (level === 0) {
      return;
    }

    var availabilityLevels = layer.availabilityLevels;
    var parentLevel =
      level % availabilityLevels === 0
        ? level - availabilityLevels
        : ((level / availabilityLevels) | 0) * availabilityLevels;
    var divisor = 1 << (level - parentLevel);
    var parentX = (x / divisor) | 0;
    var parentY = (y / divisor) | 0;

    return {
      level: parentLevel,
      x: parentX,
      y: parentY,
    };
  }

  function checkLayer(provider, x, y, level, layer, topLayer) {
    if (!defined(layer.availabilityLevels)) {
      // It's definitely not in this layer
      return {
        result: false,
      };
    }

    var cacheKey;
    var deleteFromCache = function () {
      delete layer.availabilityPromiseCache[cacheKey];
    };
    var availabilityTilesLoaded = layer.availabilityTilesLoaded;
    var availability = layer.availability;

    var tile = getAvailabilityTile(layer, x, y, level);
    while (defined(tile)) {
      if (
        availability.isTileAvailable(tile.level, tile.x, tile.y) &&
        !availabilityTilesLoaded.isTileAvailable(tile.level, tile.x, tile.y)
      ) {
        var requestPromise;
        if (!topLayer) {
          cacheKey = tile.level + "-" + tile.x + "-" + tile.y;
          requestPromise = layer.availabilityPromiseCache[cacheKey];
          if (!defined(requestPromise)) {
            // For cutout terrain, if this isn't the top layer the availability tiles
            //  may never get loaded, so request it here.
            var request = new Request({
              throttle: true,
              throttleByServer: true,
              type: RequestType$1.TERRAIN,
            });
            requestPromise = requestTileGeometry(
              provider,
              tile.x,
              tile.y,
              tile.level,
              layer,
              request
            );
            if (defined(requestPromise)) {
              layer.availabilityPromiseCache[cacheKey] = requestPromise;
              requestPromise.then(deleteFromCache);
            }
          }
        }

        // The availability tile is available, but not loaded, so there
        //  is still a chance that it may become available at some point
        return {
          result: true,
          promise: requestPromise,
        };
      }

      tile = getAvailabilityTile(layer, tile.x, tile.y, tile.level);
    }

    return {
      result: false,
    };
  }

  // Used for testing
  CesiumTerrainProvider._getAvailabilityTile = getAvailabilityTile;

  var EllipseGeometryLibrary = {};

  var rotAxis = new Cartesian3();
  var tempVec = new Cartesian3();
  var unitQuat = new Quaternion();
  var rotMtx = new Matrix3();

  function pointOnEllipsoid(
    theta,
    rotation,
    northVec,
    eastVec,
    aSqr,
    ab,
    bSqr,
    mag,
    unitPos,
    result
  ) {
    var azimuth = theta + rotation;

    Cartesian3.multiplyByScalar(eastVec, Math.cos(azimuth), rotAxis);
    Cartesian3.multiplyByScalar(northVec, Math.sin(azimuth), tempVec);
    Cartesian3.add(rotAxis, tempVec, rotAxis);

    var cosThetaSquared = Math.cos(theta);
    cosThetaSquared = cosThetaSquared * cosThetaSquared;

    var sinThetaSquared = Math.sin(theta);
    sinThetaSquared = sinThetaSquared * sinThetaSquared;

    var radius = ab / Math.sqrt(bSqr * cosThetaSquared + aSqr * sinThetaSquared);
    var angle = radius / mag;

    // Create the quaternion to rotate the position vector to the boundary of the ellipse.
    Quaternion.fromAxisAngle(rotAxis, angle, unitQuat);
    Matrix3.fromQuaternion(unitQuat, rotMtx);

    Matrix3.multiplyByVector(rotMtx, unitPos, result);
    Cartesian3.normalize(result, result);
    Cartesian3.multiplyByScalar(result, mag, result);
    return result;
  }

  var scratchCartesian1$1 = new Cartesian3();
  var scratchCartesian2$1 = new Cartesian3();
  var scratchCartesian3$2 = new Cartesian3();
  var scratchNormal$1 = new Cartesian3();
  /**
   * Returns the positions raised to the given heights
   * @private
   */
  EllipseGeometryLibrary.raisePositionsToHeight = function (
    positions,
    options,
    extrude
  ) {
    var ellipsoid = options.ellipsoid;
    var height = options.height;
    var extrudedHeight = options.extrudedHeight;
    var size = extrude ? (positions.length / 3) * 2 : positions.length / 3;

    var finalPositions = new Float64Array(size * 3);

    var length = positions.length;
    var bottomOffset = extrude ? length : 0;
    for (var i = 0; i < length; i += 3) {
      var i1 = i + 1;
      var i2 = i + 2;

      var position = Cartesian3.fromArray(positions, i, scratchCartesian1$1);
      ellipsoid.scaleToGeodeticSurface(position, position);

      var extrudedPosition = Cartesian3.clone(position, scratchCartesian2$1);
      var normal = ellipsoid.geodeticSurfaceNormal(position, scratchNormal$1);
      var scaledNormal = Cartesian3.multiplyByScalar(
        normal,
        height,
        scratchCartesian3$2
      );
      Cartesian3.add(position, scaledNormal, position);

      if (extrude) {
        Cartesian3.multiplyByScalar(normal, extrudedHeight, scaledNormal);
        Cartesian3.add(extrudedPosition, scaledNormal, extrudedPosition);

        finalPositions[i + bottomOffset] = extrudedPosition.x;
        finalPositions[i1 + bottomOffset] = extrudedPosition.y;
        finalPositions[i2 + bottomOffset] = extrudedPosition.z;
      }

      finalPositions[i] = position.x;
      finalPositions[i1] = position.y;
      finalPositions[i2] = position.z;
    }

    return finalPositions;
  };

  var unitPosScratch = new Cartesian3();
  var eastVecScratch = new Cartesian3();
  var northVecScratch = new Cartesian3();
  /**
   * Returns an array of positions that make up the ellipse.
   * @private
   */
  EllipseGeometryLibrary.computeEllipsePositions = function (
    options,
    addFillPositions,
    addEdgePositions
  ) {
    var semiMinorAxis = options.semiMinorAxis;
    var semiMajorAxis = options.semiMajorAxis;
    var rotation = options.rotation;
    var center = options.center;

    // Computing the arc-length of the ellipse is too expensive to be practical. Estimating it using the
    // arc length of the sphere is too inaccurate and creates sharp edges when either the semi-major or
    // semi-minor axis is much bigger than the other. Instead, scale the angle delta to make
    // the distance along the ellipse boundary more closely match the granularity.
    var granularity = options.granularity * 8.0;

    var aSqr = semiMinorAxis * semiMinorAxis;
    var bSqr = semiMajorAxis * semiMajorAxis;
    var ab = semiMajorAxis * semiMinorAxis;

    var mag = Cartesian3.magnitude(center);

    var unitPos = Cartesian3.normalize(center, unitPosScratch);
    var eastVec = Cartesian3.cross(Cartesian3.UNIT_Z, center, eastVecScratch);
    eastVec = Cartesian3.normalize(eastVec, eastVec);
    var northVec = Cartesian3.cross(unitPos, eastVec, northVecScratch);

    // The number of points in the first quadrant
    var numPts = 1 + Math.ceil(CesiumMath.PI_OVER_TWO / granularity);

    var deltaTheta = CesiumMath.PI_OVER_TWO / (numPts - 1);
    var theta = CesiumMath.PI_OVER_TWO - numPts * deltaTheta;
    if (theta < 0.0) {
      numPts -= Math.ceil(Math.abs(theta) / deltaTheta);
    }

    // If the number of points were three, the ellipse
    // would be tessellated like below:
    //
    //         *---*
    //       / | \ | \
    //     *---*---*---*
    //   / | \ | \ | \ | \
    //  / .*---*---*---*. \
    // * ` | \ | \ | \ | `*
    //  \`.*---*---*---*.`/
    //   \ | \ | \ | \ | /
    //     *---*---*---*
    //       \ | \ | /
    //         *---*
    // The first and last column have one position and fan to connect to the adjacent column.
    // Each other vertical column contains an even number of positions.
    var size = 2 * (numPts * (numPts + 2));
    var positions = addFillPositions ? new Array(size * 3) : undefined;
    var positionIndex = 0;
    var position = scratchCartesian1$1;
    var reflectedPosition = scratchCartesian2$1;

    var outerPositionsLength = numPts * 4 * 3;
    var outerRightIndex = outerPositionsLength - 1;
    var outerLeftIndex = 0;
    var outerPositions = addEdgePositions
      ? new Array(outerPositionsLength)
      : undefined;

    var i;
    var j;
    var numInterior;
    var t;
    var interiorPosition;

    // Compute points in the 'eastern' half of the ellipse
    theta = CesiumMath.PI_OVER_TWO;
    position = pointOnEllipsoid(
      theta,
      rotation,
      northVec,
      eastVec,
      aSqr,
      ab,
      bSqr,
      mag,
      unitPos,
      position
    );
    if (addFillPositions) {
      positions[positionIndex++] = position.x;
      positions[positionIndex++] = position.y;
      positions[positionIndex++] = position.z;
    }
    if (addEdgePositions) {
      outerPositions[outerRightIndex--] = position.z;
      outerPositions[outerRightIndex--] = position.y;
      outerPositions[outerRightIndex--] = position.x;
    }
    theta = CesiumMath.PI_OVER_TWO - deltaTheta;
    for (i = 1; i < numPts + 1; ++i) {
      position = pointOnEllipsoid(
        theta,
        rotation,
        northVec,
        eastVec,
        aSqr,
        ab,
        bSqr,
        mag,
        unitPos,
        position
      );
      reflectedPosition = pointOnEllipsoid(
        Math.PI - theta,
        rotation,
        northVec,
        eastVec,
        aSqr,
        ab,
        bSqr,
        mag,
        unitPos,
        reflectedPosition
      );

      if (addFillPositions) {
        positions[positionIndex++] = position.x;
        positions[positionIndex++] = position.y;
        positions[positionIndex++] = position.z;

        numInterior = 2 * i + 2;
        for (j = 1; j < numInterior - 1; ++j) {
          t = j / (numInterior - 1);
          interiorPosition = Cartesian3.lerp(
            position,
            reflectedPosition,
            t,
            scratchCartesian3$2
          );
          positions[positionIndex++] = interiorPosition.x;
          positions[positionIndex++] = interiorPosition.y;
          positions[positionIndex++] = interiorPosition.z;
        }

        positions[positionIndex++] = reflectedPosition.x;
        positions[positionIndex++] = reflectedPosition.y;
        positions[positionIndex++] = reflectedPosition.z;
      }

      if (addEdgePositions) {
        outerPositions[outerRightIndex--] = position.z;
        outerPositions[outerRightIndex--] = position.y;
        outerPositions[outerRightIndex--] = position.x;
        outerPositions[outerLeftIndex++] = reflectedPosition.x;
        outerPositions[outerLeftIndex++] = reflectedPosition.y;
        outerPositions[outerLeftIndex++] = reflectedPosition.z;
      }

      theta = CesiumMath.PI_OVER_TWO - (i + 1) * deltaTheta;
    }

    // Compute points in the 'western' half of the ellipse
    for (i = numPts; i > 1; --i) {
      theta = CesiumMath.PI_OVER_TWO - (i - 1) * deltaTheta;

      position = pointOnEllipsoid(
        -theta,
        rotation,
        northVec,
        eastVec,
        aSqr,
        ab,
        bSqr,
        mag,
        unitPos,
        position
      );
      reflectedPosition = pointOnEllipsoid(
        theta + Math.PI,
        rotation,
        northVec,
        eastVec,
        aSqr,
        ab,
        bSqr,
        mag,
        unitPos,
        reflectedPosition
      );

      if (addFillPositions) {
        positions[positionIndex++] = position.x;
        positions[positionIndex++] = position.y;
        positions[positionIndex++] = position.z;

        numInterior = 2 * (i - 1) + 2;
        for (j = 1; j < numInterior - 1; ++j) {
          t = j / (numInterior - 1);
          interiorPosition = Cartesian3.lerp(
            position,
            reflectedPosition,
            t,
            scratchCartesian3$2
          );
          positions[positionIndex++] = interiorPosition.x;
          positions[positionIndex++] = interiorPosition.y;
          positions[positionIndex++] = interiorPosition.z;
        }

        positions[positionIndex++] = reflectedPosition.x;
        positions[positionIndex++] = reflectedPosition.y;
        positions[positionIndex++] = reflectedPosition.z;
      }

      if (addEdgePositions) {
        outerPositions[outerRightIndex--] = position.z;
        outerPositions[outerRightIndex--] = position.y;
        outerPositions[outerRightIndex--] = position.x;
        outerPositions[outerLeftIndex++] = reflectedPosition.x;
        outerPositions[outerLeftIndex++] = reflectedPosition.y;
        outerPositions[outerLeftIndex++] = reflectedPosition.z;
      }
    }

    theta = CesiumMath.PI_OVER_TWO;
    position = pointOnEllipsoid(
      -theta,
      rotation,
      northVec,
      eastVec,
      aSqr,
      ab,
      bSqr,
      mag,
      unitPos,
      position
    );

    var r = {};
    if (addFillPositions) {
      positions[positionIndex++] = position.x;
      positions[positionIndex++] = position.y;
      positions[positionIndex++] = position.z;
      r.positions = positions;
      r.numPts = numPts;
    }
    if (addEdgePositions) {
      outerPositions[outerRightIndex--] = position.z;
      outerPositions[outerRightIndex--] = position.y;
      outerPositions[outerRightIndex--] = position.x;
      r.outerPositions = outerPositions;
    }

    return r;
  };

  /**
   * Geometry instancing allows one {@link Geometry} object to be positions in several
   * different locations and colored uniquely.  For example, one {@link BoxGeometry} can
   * be instanced several times, each with a different <code>modelMatrix</code> to change
   * its position, rotation, and scale.
   *
   * @alias GeometryInstance
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Geometry|GeometryFactory} options.geometry The geometry to instance.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The model matrix that transforms to transform the geometry from model to world coordinates.
   * @param {Object} [options.id] A user-defined object to return when the instance is picked with {@link Scene#pick} or get/set per-instance attributes with {@link Primitive#getGeometryInstanceAttributes}.
   * @param {Object} [options.attributes] Per-instance attributes like a show or color attribute shown in the example below.
   *
   *
   * @example
   * // Create geometry for a box, and two instances that refer to it.
   * // One instance positions the box on the bottom and colored aqua.
   * // The other instance positions the box on the top and color white.
   * var geometry = Cesium.BoxGeometry.fromDimensions({
   *   vertexFormat : Cesium.VertexFormat.POSITION_AND_NORMAL,
   *   dimensions : new Cesium.Cartesian3(1000000.0, 1000000.0, 500000.0)
   * });
   * var instanceBottom = new Cesium.GeometryInstance({
   *   geometry : geometry,
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 1000000.0), new Cesium.Matrix4()),
   *   attributes : {
   *     color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.AQUA)
   *   },
   *   id : 'bottom'
   * });
   * var instanceTop = new Cesium.GeometryInstance({
   *   geometry : geometry,
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 3000000.0), new Cesium.Matrix4()),
   *   attributes : {
   *     color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.AQUA)
   *   },
   *   id : 'top'
   * });
   *
   * @see Geometry
   */
  function GeometryInstance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.geometry)) {
      throw new DeveloperError("options.geometry is required.");
    }
    //>>includeEnd('debug');

    /**
     * The geometry being instanced.
     *
     * @type Geometry
     *
     * @default undefined
     */
    this.geometry = options.geometry;

    /**
     * The 4x4 transformation matrix that transforms the geometry from model to world coordinates.
     * When this is the identity matrix, the geometry is drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type Matrix4
     *
     * @default Matrix4.IDENTITY
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );

    /**
     * User-defined object returned when the instance is picked or used to get/set per-instance attributes.
     *
     * @type Object
     *
     * @default undefined
     *
     * @see Scene#pick
     * @see Primitive#getGeometryInstanceAttributes
     */
    this.id = options.id;

    /**
     * Used for picking primitives that wrap geometry instances.
     *
     * @private
     */
    this.pickPrimitive = options.pickPrimitive;

    /**
     * Per-instance attributes like {@link ColorGeometryInstanceAttribute} or {@link ShowGeometryInstanceAttribute}.
     * {@link Geometry} attributes varying per vertex; these attributes are constant for the entire instance.
     *
     * @type Object
     *
     * @default undefined
     */
    this.attributes = defaultValue(options.attributes, {});

    /**
     * @private
     */
    this.westHemisphereGeometry = undefined;
    /**
     * @private
     */
    this.eastHemisphereGeometry = undefined;
  }

  var scratchCartesian1$2 = new Cartesian3();
  var scratchCartesian2$2 = new Cartesian3();
  var scratchCartesian3$3 = new Cartesian3();

  /**
   * Computes the barycentric coordinates for a point with respect to a triangle.
   *
   * @function
   *
   * @param {Cartesian2|Cartesian3} point The point to test.
   * @param {Cartesian2|Cartesian3} p0 The first point of the triangle, corresponding to the barycentric x-axis.
   * @param {Cartesian2|Cartesian3} p1 The second point of the triangle, corresponding to the barycentric y-axis.
   * @param {Cartesian2|Cartesian3} p2 The third point of the triangle, corresponding to the barycentric z-axis.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided.
   *
   * @example
   * // Returns Cartesian3.UNIT_X
   * var p = new Cesium.Cartesian3(-1.0, 0.0, 0.0);
   * var b = Cesium.barycentricCoordinates(p,
   *   new Cesium.Cartesian3(-1.0, 0.0, 0.0),
   *   new Cesium.Cartesian3( 1.0, 0.0, 0.0),
   *   new Cesium.Cartesian3( 0.0, 1.0, 1.0));
   */
  function barycentricCoordinates(point, p0, p1, p2, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("point", point);
    Check.defined("p0", p0);
    Check.defined("p1", p1);
    Check.defined("p2", p2);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }

    // Implementation based on http://www.blackpawn.com/texts/pointinpoly/default.html.
    var v0;
    var v1;
    var v2;
    var dot00;
    var dot01;
    var dot02;
    var dot11;
    var dot12;

    if (!defined(p0.z)) {
      if (Cartesian2.equalsEpsilon(point, p0, CesiumMath.EPSILON14)) {
        return Cartesian3.clone(Cartesian3.UNIT_X, result);
      }
      if (Cartesian2.equalsEpsilon(point, p1, CesiumMath.EPSILON14)) {
        return Cartesian3.clone(Cartesian3.UNIT_Y, result);
      }
      if (Cartesian2.equalsEpsilon(point, p2, CesiumMath.EPSILON14)) {
        return Cartesian3.clone(Cartesian3.UNIT_Z, result);
      }

      v0 = Cartesian2.subtract(p1, p0, scratchCartesian1$2);
      v1 = Cartesian2.subtract(p2, p0, scratchCartesian2$2);
      v2 = Cartesian2.subtract(point, p0, scratchCartesian3$3);

      dot00 = Cartesian2.dot(v0, v0);
      dot01 = Cartesian2.dot(v0, v1);
      dot02 = Cartesian2.dot(v0, v2);
      dot11 = Cartesian2.dot(v1, v1);
      dot12 = Cartesian2.dot(v1, v2);
    } else {
      if (Cartesian3.equalsEpsilon(point, p0, CesiumMath.EPSILON14)) {
        return Cartesian3.clone(Cartesian3.UNIT_X, result);
      }
      if (Cartesian3.equalsEpsilon(point, p1, CesiumMath.EPSILON14)) {
        return Cartesian3.clone(Cartesian3.UNIT_Y, result);
      }
      if (Cartesian3.equalsEpsilon(point, p2, CesiumMath.EPSILON14)) {
        return Cartesian3.clone(Cartesian3.UNIT_Z, result);
      }

      v0 = Cartesian3.subtract(p1, p0, scratchCartesian1$2);
      v1 = Cartesian3.subtract(p2, p0, scratchCartesian2$2);
      v2 = Cartesian3.subtract(point, p0, scratchCartesian3$3);

      dot00 = Cartesian3.dot(v0, v0);
      dot01 = Cartesian3.dot(v0, v1);
      dot02 = Cartesian3.dot(v0, v2);
      dot11 = Cartesian3.dot(v1, v1);
      dot12 = Cartesian3.dot(v1, v2);
    }

    result.y = dot11 * dot02 - dot01 * dot12;
    result.z = dot00 * dot12 - dot01 * dot02;
    var q = dot00 * dot11 - dot01 * dot01;

    // This is done to avoid dividing by infinity causing a NaN
    if (result.y !== 0) {
      result.y /= q;
    }
    if (result.z !== 0) {
      result.z /= q;
    }

    result.x = 1.0 - result.y - result.z;
    return result;
  }

  /**
   * A fixed-point encoding of a {@link Cartesian3} with 64-bit floating-point components, as two {@link Cartesian3}
   * values that, when converted to 32-bit floating-point and added, approximate the original input.
   * <p>
   * This is used to encode positions in vertex buffers for rendering without jittering artifacts
   * as described in {@link http://help.agi.com/AGIComponents/html/BlogPrecisionsPrecisions.htm|Precisions, Precisions}.
   * </p>
   *
   * @alias EncodedCartesian3
   * @constructor
   *
   * @private
   */
  function EncodedCartesian3() {
    /**
     * The high bits for each component.  Bits 0 to 22 store the whole value.  Bits 23 to 31 are not used.
     *
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.high = Cartesian3.clone(Cartesian3.ZERO);

    /**
     * The low bits for each component.  Bits 7 to 22 store the whole value, and bits 0 to 6 store the fraction.  Bits 23 to 31 are not used.
     *
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     */
    this.low = Cartesian3.clone(Cartesian3.ZERO);
  }

  /**
   * Encodes a 64-bit floating-point value as two floating-point values that, when converted to
   * 32-bit floating-point and added, approximate the original input.  The returned object
   * has <code>high</code> and <code>low</code> properties for the high and low bits, respectively.
   * <p>
   * The fixed-point encoding follows {@link http://help.agi.com/AGIComponents/html/BlogPrecisionsPrecisions.htm|Precisions, Precisions}.
   * </p>
   *
   * @param {Number} value The floating-point value to encode.
   * @param {Object} [result] The object onto which to store the result.
   * @returns {Object} The modified result parameter or a new instance if one was not provided.
   *
   * @example
   * var value = 1234567.1234567;
   * var splitValue = Cesium.EncodedCartesian3.encode(value);
   */
  EncodedCartesian3.encode = function (value, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("value", value);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = {
        high: 0.0,
        low: 0.0,
      };
    }

    var doubleHigh;
    if (value >= 0.0) {
      doubleHigh = Math.floor(value / 65536.0) * 65536.0;
      result.high = doubleHigh;
      result.low = value - doubleHigh;
    } else {
      doubleHigh = Math.floor(-value / 65536.0) * 65536.0;
      result.high = -doubleHigh;
      result.low = value + doubleHigh;
    }

    return result;
  };

  var scratchEncode = {
    high: 0.0,
    low: 0.0,
  };

  /**
   * Encodes a {@link Cartesian3} with 64-bit floating-point components as two {@link Cartesian3}
   * values that, when converted to 32-bit floating-point and added, approximate the original input.
   * <p>
   * The fixed-point encoding follows {@link http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/|Precisions, Precisions}.
   * </p>
   *
   * @param {Cartesian3} cartesian The cartesian to encode.
   * @param {EncodedCartesian3} [result] The object onto which to store the result.
   * @returns {EncodedCartesian3} The modified result parameter or a new EncodedCartesian3 instance if one was not provided.
   *
   * @example
   * var cart = new Cesium.Cartesian3(-10000000.0, 0.0, 10000000.0);
   * var encoded = Cesium.EncodedCartesian3.fromCartesian(cart);
   */
  EncodedCartesian3.fromCartesian = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new EncodedCartesian3();
    }

    var high = result.high;
    var low = result.low;

    EncodedCartesian3.encode(cartesian.x, scratchEncode);
    high.x = scratchEncode.high;
    low.x = scratchEncode.low;

    EncodedCartesian3.encode(cartesian.y, scratchEncode);
    high.y = scratchEncode.high;
    low.y = scratchEncode.low;

    EncodedCartesian3.encode(cartesian.z, scratchEncode);
    high.z = scratchEncode.high;
    low.z = scratchEncode.low;

    return result;
  };

  var encodedP = new EncodedCartesian3();

  /**
   * Encodes the provided <code>cartesian</code>, and writes it to an array with <code>high</code>
   * components followed by <code>low</code> components, i.e. <code>[high.x, high.y, high.z, low.x, low.y, low.z]</code>.
   * <p>
   * This is used to create interleaved high-precision position vertex attributes.
   * </p>
   *
   * @param {Cartesian3} cartesian The cartesian to encode.
   * @param {Number[]} cartesianArray The array to write to.
   * @param {Number} index The index into the array to start writing.  Six elements will be written.
   *
   * @exception {DeveloperError} index must be a number greater than or equal to 0.
   *
   * @example
   * var positions = [
   *    new Cesium.Cartesian3(),
   *    // ...
   * ];
   * var encodedPositions = new Float32Array(2 * 3 * positions.length);
   * var j = 0;
   * for (var i = 0; i < positions.length; ++i) {
   *   Cesium.EncodedCartesian3.writeElement(positions[i], encodedPositions, j);
   *   j += 6;
   * }
   */
  EncodedCartesian3.writeElements = function (cartesian, cartesianArray, index) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesianArray", cartesianArray);
    Check.typeOf.number("index", index);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    //>>includeEnd('debug');

    EncodedCartesian3.fromCartesian(cartesian, encodedP);
    var high = encodedP.high;
    var low = encodedP.low;

    cartesianArray[index] = high.x;
    cartesianArray[index + 1] = high.y;
    cartesianArray[index + 2] = high.z;
    cartesianArray[index + 3] = low.x;
    cartesianArray[index + 4] = low.y;
    cartesianArray[index + 5] = low.z;
  };

  /**
   * Encapsulates an algorithm to optimize triangles for the post
   * vertex-shader cache.  This is based on the 2007 SIGGRAPH paper
   * 'Fast Triangle Reordering for Vertex Locality and Reduced Overdraw.'
   * The runtime is linear but several passes are made.
   *
   * @namespace Tipsify
   *
   * @see <a href='http://gfx.cs.princeton.edu/pubs/Sander_2007_%3ETR/tipsy.pdf'>
   * Fast Triangle Reordering for Vertex Locality and Reduced Overdraw</a>
   * by Sander, Nehab, and Barczak
   *
   * @private
   */
  var Tipsify = {};

  /**
   * Calculates the average cache miss ratio (ACMR) for a given set of indices.
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.indices Lists triads of numbers corresponding to the indices of the vertices
   *                        in the vertex buffer that define the geometry's triangles.
   * @param {Number} [options.maximumIndex] The maximum value of the elements in <code>args.indices</code>.
   *                                     If not supplied, this value will be computed.
   * @param {Number} [options.cacheSize=24] The number of vertices that can be stored in the cache at any one time.
   * @returns {Number} The average cache miss ratio (ACMR).
   *
   * @exception {DeveloperError} indices length must be a multiple of three.
   * @exception {DeveloperError} cacheSize must be greater than two.
   *
   * @example
   * var indices = [0, 1, 2, 3, 4, 5];
   * var maxIndex = 5;
   * var cacheSize = 3;
   * var acmr = Cesium.Tipsify.calculateACMR({indices : indices, maxIndex : maxIndex, cacheSize : cacheSize});
   */
  Tipsify.calculateACMR = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var indices = options.indices;
    var maximumIndex = options.maximumIndex;
    var cacheSize = defaultValue(options.cacheSize, 24);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(indices)) {
      throw new DeveloperError("indices is required.");
    }
    //>>includeEnd('debug');

    var numIndices = indices.length;

    //>>includeStart('debug', pragmas.debug);
    if (numIndices < 3 || numIndices % 3 !== 0) {
      throw new DeveloperError("indices length must be a multiple of three.");
    }
    if (maximumIndex <= 0) {
      throw new DeveloperError("maximumIndex must be greater than zero.");
    }
    if (cacheSize < 3) {
      throw new DeveloperError("cacheSize must be greater than two.");
    }
    //>>includeEnd('debug');

    // Compute the maximumIndex if not given
    if (!defined(maximumIndex)) {
      maximumIndex = 0;
      var currentIndex = 0;
      var intoIndices = indices[currentIndex];
      while (currentIndex < numIndices) {
        if (intoIndices > maximumIndex) {
          maximumIndex = intoIndices;
        }
        ++currentIndex;
        intoIndices = indices[currentIndex];
      }
    }

    // Vertex time stamps
    var vertexTimeStamps = [];
    for (var i = 0; i < maximumIndex + 1; i++) {
      vertexTimeStamps[i] = 0;
    }

    // Cache processing
    var s = cacheSize + 1;
    for (var j = 0; j < numIndices; ++j) {
      if (s - vertexTimeStamps[indices[j]] > cacheSize) {
        vertexTimeStamps[indices[j]] = s;
        ++s;
      }
    }

    return (s - cacheSize + 1) / (numIndices / 3);
  };

  /**
   * Optimizes triangles for the post-vertex shader cache.
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.indices Lists triads of numbers corresponding to the indices of the vertices
   *                        in the vertex buffer that define the geometry's triangles.
   * @param {Number} [options.maximumIndex] The maximum value of the elements in <code>args.indices</code>.
   *                                     If not supplied, this value will be computed.
   * @param {Number} [options.cacheSize=24] The number of vertices that can be stored in the cache at any one time.
   * @returns {Number[]} A list of the input indices in an optimized order.
   *
   * @exception {DeveloperError} indices length must be a multiple of three.
   * @exception {DeveloperError} cacheSize must be greater than two.
   *
   * @example
   * var indices = [0, 1, 2, 3, 4, 5];
   * var maxIndex = 5;
   * var cacheSize = 3;
   * var reorderedIndices = Cesium.Tipsify.tipsify({indices : indices, maxIndex : maxIndex, cacheSize : cacheSize});
   */
  Tipsify.tipsify = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var indices = options.indices;
    var maximumIndex = options.maximumIndex;
    var cacheSize = defaultValue(options.cacheSize, 24);

    var cursor;

    function skipDeadEnd(vertices, deadEnd, indices, maximumIndexPlusOne) {
      while (deadEnd.length >= 1) {
        // while the stack is not empty
        var d = deadEnd[deadEnd.length - 1]; // top of the stack
        deadEnd.splice(deadEnd.length - 1, 1); // pop the stack

        if (vertices[d].numLiveTriangles > 0) {
          return d;
        }
      }

      while (cursor < maximumIndexPlusOne) {
        if (vertices[cursor].numLiveTriangles > 0) {
          ++cursor;
          return cursor - 1;
        }
        ++cursor;
      }
      return -1;
    }

    function getNextVertex(
      indices,
      cacheSize,
      oneRing,
      vertices,
      s,
      deadEnd,
      maximumIndexPlusOne
    ) {
      var n = -1;
      var p;
      var m = -1;
      var itOneRing = 0;
      while (itOneRing < oneRing.length) {
        var index = oneRing[itOneRing];
        if (vertices[index].numLiveTriangles) {
          p = 0;
          if (
            s -
              vertices[index].timeStamp +
              2 * vertices[index].numLiveTriangles <=
            cacheSize
          ) {
            p = s - vertices[index].timeStamp;
          }
          if (p > m || m === -1) {
            m = p;
            n = index;
          }
        }
        ++itOneRing;
      }
      if (n === -1) {
        return skipDeadEnd(vertices, deadEnd, indices, maximumIndexPlusOne);
      }
      return n;
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(indices)) {
      throw new DeveloperError("indices is required.");
    }
    //>>includeEnd('debug');

    var numIndices = indices.length;

    //>>includeStart('debug', pragmas.debug);
    if (numIndices < 3 || numIndices % 3 !== 0) {
      throw new DeveloperError("indices length must be a multiple of three.");
    }
    if (maximumIndex <= 0) {
      throw new DeveloperError("maximumIndex must be greater than zero.");
    }
    if (cacheSize < 3) {
      throw new DeveloperError("cacheSize must be greater than two.");
    }
    //>>includeEnd('debug');

    // Determine maximum index
    var maximumIndexPlusOne = 0;
    var currentIndex = 0;
    var intoIndices = indices[currentIndex];
    var endIndex = numIndices;
    if (defined(maximumIndex)) {
      maximumIndexPlusOne = maximumIndex + 1;
    } else {
      while (currentIndex < endIndex) {
        if (intoIndices > maximumIndexPlusOne) {
          maximumIndexPlusOne = intoIndices;
        }
        ++currentIndex;
        intoIndices = indices[currentIndex];
      }
      if (maximumIndexPlusOne === -1) {
        return 0;
      }
      ++maximumIndexPlusOne;
    }

    // Vertices
    var vertices = [];
    var i;
    for (i = 0; i < maximumIndexPlusOne; i++) {
      vertices[i] = {
        numLiveTriangles: 0,
        timeStamp: 0,
        vertexTriangles: [],
      };
    }
    currentIndex = 0;
    var triangle = 0;
    while (currentIndex < endIndex) {
      vertices[indices[currentIndex]].vertexTriangles.push(triangle);
      ++vertices[indices[currentIndex]].numLiveTriangles;
      vertices[indices[currentIndex + 1]].vertexTriangles.push(triangle);
      ++vertices[indices[currentIndex + 1]].numLiveTriangles;
      vertices[indices[currentIndex + 2]].vertexTriangles.push(triangle);
      ++vertices[indices[currentIndex + 2]].numLiveTriangles;
      ++triangle;
      currentIndex += 3;
    }

    // Starting index
    var f = 0;

    // Time Stamp
    var s = cacheSize + 1;
    cursor = 1;

    // Process
    var oneRing = [];
    var deadEnd = []; //Stack
    var vertex;
    var intoVertices;
    var currentOutputIndex = 0;
    var outputIndices = [];
    var numTriangles = numIndices / 3;
    var triangleEmitted = [];
    for (i = 0; i < numTriangles; i++) {
      triangleEmitted[i] = false;
    }
    var index;
    var limit;
    while (f !== -1) {
      oneRing = [];
      intoVertices = vertices[f];
      limit = intoVertices.vertexTriangles.length;
      for (var k = 0; k < limit; ++k) {
        triangle = intoVertices.vertexTriangles[k];
        if (!triangleEmitted[triangle]) {
          triangleEmitted[triangle] = true;
          currentIndex = triangle + triangle + triangle;
          for (var j = 0; j < 3; ++j) {
            // Set this index as a possible next index
            index = indices[currentIndex];
            oneRing.push(index);
            deadEnd.push(index);

            // Output index
            outputIndices[currentOutputIndex] = index;
            ++currentOutputIndex;

            // Cache processing
            vertex = vertices[index];
            --vertex.numLiveTriangles;
            if (s - vertex.timeStamp > cacheSize) {
              vertex.timeStamp = s;
              ++s;
            }
            ++currentIndex;
          }
        }
      }
      f = getNextVertex(
        indices,
        cacheSize,
        oneRing,
        vertices,
        s,
        deadEnd,
        maximumIndexPlusOne
      );
    }

    return outputIndices;
  };

  /**
   * Content pipeline functions for geometries.
   *
   * @namespace GeometryPipeline
   *
   * @see Geometry
   */
  var GeometryPipeline = {};

  function addTriangle(lines, index, i0, i1, i2) {
    lines[index++] = i0;
    lines[index++] = i1;

    lines[index++] = i1;
    lines[index++] = i2;

    lines[index++] = i2;
    lines[index] = i0;
  }

  function trianglesToLines(triangles) {
    var count = triangles.length;
    var size = (count / 3) * 6;
    var lines = IndexDatatype$1.createTypedArray(count, size);

    var index = 0;
    for (var i = 0; i < count; i += 3, index += 6) {
      addTriangle(lines, index, triangles[i], triangles[i + 1], triangles[i + 2]);
    }

    return lines;
  }

  function triangleStripToLines(triangles) {
    var count = triangles.length;
    if (count >= 3) {
      var size = (count - 2) * 6;
      var lines = IndexDatatype$1.createTypedArray(count, size);

      addTriangle(lines, 0, triangles[0], triangles[1], triangles[2]);
      var index = 6;

      for (var i = 3; i < count; ++i, index += 6) {
        addTriangle(
          lines,
          index,
          triangles[i - 1],
          triangles[i],
          triangles[i - 2]
        );
      }

      return lines;
    }

    return new Uint16Array();
  }

  function triangleFanToLines(triangles) {
    if (triangles.length > 0) {
      var count = triangles.length - 1;
      var size = (count - 1) * 6;
      var lines = IndexDatatype$1.createTypedArray(count, size);

      var base = triangles[0];
      var index = 0;
      for (var i = 1; i < count; ++i, index += 6) {
        addTriangle(lines, index, base, triangles[i], triangles[i + 1]);
      }

      return lines;
    }

    return new Uint16Array();
  }

  /**
   * Converts a geometry's triangle indices to line indices.  If the geometry has an <code>indices</code>
   * and its <code>primitiveType</code> is <code>TRIANGLES</code>, <code>TRIANGLE_STRIP</code>,
   * <code>TRIANGLE_FAN</code>, it is converted to <code>LINES</code>; otherwise, the geometry is not changed.
   * <p>
   * This is commonly used to create a wireframe geometry for visual debugging.
   * </p>
   *
   * @param {Geometry} geometry The geometry to modify.
   * @returns {Geometry} The modified <code>geometry</code> argument, with its triangle indices converted to lines.
   *
   * @exception {DeveloperError} geometry.primitiveType must be TRIANGLES, TRIANGLE_STRIP, or TRIANGLE_FAN.
   *
   * @example
   * geometry = Cesium.GeometryPipeline.toWireframe(geometry);
   */
  GeometryPipeline.toWireframe = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    //>>includeEnd('debug');

    var indices = geometry.indices;
    if (defined(indices)) {
      switch (geometry.primitiveType) {
        case PrimitiveType$1.TRIANGLES:
          geometry.indices = trianglesToLines(indices);
          break;
        case PrimitiveType$1.TRIANGLE_STRIP:
          geometry.indices = triangleStripToLines(indices);
          break;
        case PrimitiveType$1.TRIANGLE_FAN:
          geometry.indices = triangleFanToLines(indices);
          break;
        //>>includeStart('debug', pragmas.debug);
        default:
          throw new DeveloperError(
            "geometry.primitiveType must be TRIANGLES, TRIANGLE_STRIP, or TRIANGLE_FAN."
          );
        //>>includeEnd('debug');
      }

      geometry.primitiveType = PrimitiveType$1.LINES;
    }

    return geometry;
  };

  /**
   * Creates a new {@link Geometry} with <code>LINES</code> representing the provided
   * attribute (<code>attributeName</code>) for the provided geometry.  This is used to
   * visualize vector attributes like normals, tangents, and bitangents.
   *
   * @param {Geometry} geometry The <code>Geometry</code> instance with the attribute.
   * @param {String} [attributeName='normal'] The name of the attribute.
   * @param {Number} [length=10000.0] The length of each line segment in meters.  This can be negative to point the vector in the opposite direction.
   * @returns {Geometry} A new <code>Geometry</code> instance with line segments for the vector.
   *
   * @exception {DeveloperError} geometry.attributes must have an attribute with the same name as the attributeName parameter.
   *
   * @example
   * var geometry = Cesium.GeometryPipeline.createLineSegmentsForVectors(instance.geometry, 'bitangent', 100000.0);
   */
  GeometryPipeline.createLineSegmentsForVectors = function (
    geometry,
    attributeName,
    length
  ) {
    attributeName = defaultValue(attributeName, "normal");

    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    if (!defined(geometry.attributes.position)) {
      throw new DeveloperError("geometry.attributes.position is required.");
    }
    if (!defined(geometry.attributes[attributeName])) {
      throw new DeveloperError(
        "geometry.attributes must have an attribute with the same name as the attributeName parameter, " +
          attributeName +
          "."
      );
    }
    //>>includeEnd('debug');

    length = defaultValue(length, 10000.0);

    var positions = geometry.attributes.position.values;
    var vectors = geometry.attributes[attributeName].values;
    var positionsLength = positions.length;

    var newPositions = new Float64Array(2 * positionsLength);

    var j = 0;
    for (var i = 0; i < positionsLength; i += 3) {
      newPositions[j++] = positions[i];
      newPositions[j++] = positions[i + 1];
      newPositions[j++] = positions[i + 2];

      newPositions[j++] = positions[i] + vectors[i] * length;
      newPositions[j++] = positions[i + 1] + vectors[i + 1] * length;
      newPositions[j++] = positions[i + 2] + vectors[i + 2] * length;
    }

    var newBoundingSphere;
    var bs = geometry.boundingSphere;
    if (defined(bs)) {
      newBoundingSphere = new BoundingSphere(bs.center, bs.radius + length);
    }

    return new Geometry({
      attributes: {
        position: new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.DOUBLE,
          componentsPerAttribute: 3,
          values: newPositions,
        }),
      },
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: newBoundingSphere,
    });
  };

  /**
   * Creates an object that maps attribute names to unique locations (indices)
   * for matching vertex attributes and shader programs.
   *
   * @param {Geometry} geometry The geometry, which is not modified, to create the object for.
   * @returns {Object} An object with attribute name / index pairs.
   *
   * @example
   * var attributeLocations = Cesium.GeometryPipeline.createAttributeLocations(geometry);
   * // Example output
   * // {
   * //   'position' : 0,
   * //   'normal' : 1
   * // }
   */
  GeometryPipeline.createAttributeLocations = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    //>>includeEnd('debug')

    // There can be a WebGL performance hit when attribute 0 is disabled, so
    // assign attribute locations to well-known attributes.
    var semantics = [
      "position",
      "positionHigh",
      "positionLow",

      // From VertexFormat.position - after 2D projection and high-precision encoding
      "position3DHigh",
      "position3DLow",
      "position2DHigh",
      "position2DLow",

      // From Primitive
      "pickColor",

      // From VertexFormat
      "normal",
      "st",
      "tangent",
      "bitangent",

      // For shadow volumes
      "extrudeDirection",

      // From compressing texture coordinates and normals
      "compressedAttributes",
    ];

    var attributes = geometry.attributes;
    var indices = {};
    var j = 0;
    var i;
    var len = semantics.length;

    // Attribute locations for well-known attributes
    for (i = 0; i < len; ++i) {
      var semantic = semantics[i];

      if (defined(attributes[semantic])) {
        indices[semantic] = j++;
      }
    }

    // Locations for custom attributes
    for (var name in attributes) {
      if (attributes.hasOwnProperty(name) && !defined(indices[name])) {
        indices[name] = j++;
      }
    }

    return indices;
  };

  /**
   * Reorders a geometry's attributes and <code>indices</code> to achieve better performance from the GPU's pre-vertex-shader cache.
   *
   * @param {Geometry} geometry The geometry to modify.
   * @returns {Geometry} The modified <code>geometry</code> argument, with its attributes and indices reordered for the GPU's pre-vertex-shader cache.
   *
   * @exception {DeveloperError} Each attribute array in geometry.attributes must have the same number of attributes.
   *
   *
   * @example
   * geometry = Cesium.GeometryPipeline.reorderForPreVertexCache(geometry);
   *
   * @see GeometryPipeline.reorderForPostVertexCache
   */
  GeometryPipeline.reorderForPreVertexCache = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    //>>includeEnd('debug');

    var numVertices = Geometry.computeNumberOfVertices(geometry);

    var indices = geometry.indices;
    if (defined(indices)) {
      var indexCrossReferenceOldToNew = new Int32Array(numVertices);
      for (var i = 0; i < numVertices; i++) {
        indexCrossReferenceOldToNew[i] = -1;
      }

      // Construct cross reference and reorder indices
      var indicesIn = indices;
      var numIndices = indicesIn.length;
      var indicesOut = IndexDatatype$1.createTypedArray(numVertices, numIndices);

      var intoIndicesIn = 0;
      var intoIndicesOut = 0;
      var nextIndex = 0;
      var tempIndex;
      while (intoIndicesIn < numIndices) {
        tempIndex = indexCrossReferenceOldToNew[indicesIn[intoIndicesIn]];
        if (tempIndex !== -1) {
          indicesOut[intoIndicesOut] = tempIndex;
        } else {
          tempIndex = indicesIn[intoIndicesIn];
          indexCrossReferenceOldToNew[tempIndex] = nextIndex;

          indicesOut[intoIndicesOut] = nextIndex;
          ++nextIndex;
        }
        ++intoIndicesIn;
        ++intoIndicesOut;
      }
      geometry.indices = indicesOut;

      // Reorder attributes
      var attributes = geometry.attributes;
      for (var property in attributes) {
        if (
          attributes.hasOwnProperty(property) &&
          defined(attributes[property]) &&
          defined(attributes[property].values)
        ) {
          var attribute = attributes[property];
          var elementsIn = attribute.values;
          var intoElementsIn = 0;
          var numComponents = attribute.componentsPerAttribute;
          var elementsOut = ComponentDatatype$1.createTypedArray(
            attribute.componentDatatype,
            nextIndex * numComponents
          );
          while (intoElementsIn < numVertices) {
            var temp = indexCrossReferenceOldToNew[intoElementsIn];
            if (temp !== -1) {
              for (var j = 0; j < numComponents; j++) {
                elementsOut[numComponents * temp + j] =
                  elementsIn[numComponents * intoElementsIn + j];
              }
            }
            ++intoElementsIn;
          }
          attribute.values = elementsOut;
        }
      }
    }

    return geometry;
  };

  /**
   * Reorders a geometry's <code>indices</code> to achieve better performance from the GPU's
   * post vertex-shader cache by using the Tipsify algorithm.  If the geometry <code>primitiveType</code>
   * is not <code>TRIANGLES</code> or the geometry does not have an <code>indices</code>, this function has no effect.
   *
   * @param {Geometry} geometry The geometry to modify.
   * @param {Number} [cacheCapacity=24] The number of vertices that can be held in the GPU's vertex cache.
   * @returns {Geometry} The modified <code>geometry</code> argument, with its indices reordered for the post-vertex-shader cache.
   *
   * @exception {DeveloperError} cacheCapacity must be greater than two.
   *
   *
   * @example
   * geometry = Cesium.GeometryPipeline.reorderForPostVertexCache(geometry);
   *
   * @see GeometryPipeline.reorderForPreVertexCache
   * @see {@link http://gfx.cs.princ0eton.edu/pubs/Sander_2007_%3ETR/tipsy.pdf|Fast Triangle Reordering for Vertex Locality and Reduced Overdraw}
   * by Sander, Nehab, and Barczak
   */
  GeometryPipeline.reorderForPostVertexCache = function (
    geometry,
    cacheCapacity
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    //>>includeEnd('debug');

    var indices = geometry.indices;
    if (geometry.primitiveType === PrimitiveType$1.TRIANGLES && defined(indices)) {
      var numIndices = indices.length;
      var maximumIndex = 0;
      for (var j = 0; j < numIndices; j++) {
        if (indices[j] > maximumIndex) {
          maximumIndex = indices[j];
        }
      }
      geometry.indices = Tipsify.tipsify({
        indices: indices,
        maximumIndex: maximumIndex,
        cacheSize: cacheCapacity,
      });
    }

    return geometry;
  };

  function copyAttributesDescriptions(attributes) {
    var newAttributes = {};

    for (var attribute in attributes) {
      if (
        attributes.hasOwnProperty(attribute) &&
        defined(attributes[attribute]) &&
        defined(attributes[attribute].values)
      ) {
        var attr = attributes[attribute];
        newAttributes[attribute] = new GeometryAttribute({
          componentDatatype: attr.componentDatatype,
          componentsPerAttribute: attr.componentsPerAttribute,
          normalize: attr.normalize,
          values: [],
        });
      }
    }

    return newAttributes;
  }

  function copyVertex(destinationAttributes, sourceAttributes, index) {
    for (var attribute in sourceAttributes) {
      if (
        sourceAttributes.hasOwnProperty(attribute) &&
        defined(sourceAttributes[attribute]) &&
        defined(sourceAttributes[attribute].values)
      ) {
        var attr = sourceAttributes[attribute];

        for (var k = 0; k < attr.componentsPerAttribute; ++k) {
          destinationAttributes[attribute].values.push(
            attr.values[index * attr.componentsPerAttribute + k]
          );
        }
      }
    }
  }

  /**
   * Splits a geometry into multiple geometries, if necessary, to ensure that indices in the
   * <code>indices</code> fit into unsigned shorts.  This is used to meet the WebGL requirements
   * when unsigned int indices are not supported.
   * <p>
   * If the geometry does not have any <code>indices</code>, this function has no effect.
   * </p>
   *
   * @param {Geometry} geometry The geometry to be split into multiple geometries.
   * @returns {Geometry[]} An array of geometries, each with indices that fit into unsigned shorts.
   *
   * @exception {DeveloperError} geometry.primitiveType must equal to PrimitiveType.TRIANGLES, PrimitiveType.LINES, or PrimitiveType.POINTS
   * @exception {DeveloperError} All geometry attribute lists must have the same number of attributes.
   *
   * @example
   * var geometries = Cesium.GeometryPipeline.fitToUnsignedShortIndices(geometry);
   */
  GeometryPipeline.fitToUnsignedShortIndices = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    if (
      defined(geometry.indices) &&
      geometry.primitiveType !== PrimitiveType$1.TRIANGLES &&
      geometry.primitiveType !== PrimitiveType$1.LINES &&
      geometry.primitiveType !== PrimitiveType$1.POINTS
    ) {
      throw new DeveloperError(
        "geometry.primitiveType must equal to PrimitiveType.TRIANGLES, PrimitiveType.LINES, or PrimitiveType.POINTS."
      );
    }
    //>>includeEnd('debug');

    var geometries = [];

    // If there's an index list and more than 64K attributes, it is possible that
    // some indices are outside the range of unsigned short [0, 64K - 1]
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);
    if (
      defined(geometry.indices) &&
      numberOfVertices >= CesiumMath.SIXTY_FOUR_KILOBYTES
    ) {
      var oldToNewIndex = [];
      var newIndices = [];
      var currentIndex = 0;
      var newAttributes = copyAttributesDescriptions(geometry.attributes);

      var originalIndices = geometry.indices;
      var numberOfIndices = originalIndices.length;

      var indicesPerPrimitive;

      if (geometry.primitiveType === PrimitiveType$1.TRIANGLES) {
        indicesPerPrimitive = 3;
      } else if (geometry.primitiveType === PrimitiveType$1.LINES) {
        indicesPerPrimitive = 2;
      } else if (geometry.primitiveType === PrimitiveType$1.POINTS) {
        indicesPerPrimitive = 1;
      }

      for (var j = 0; j < numberOfIndices; j += indicesPerPrimitive) {
        for (var k = 0; k < indicesPerPrimitive; ++k) {
          var x = originalIndices[j + k];
          var i = oldToNewIndex[x];
          if (!defined(i)) {
            i = currentIndex++;
            oldToNewIndex[x] = i;
            copyVertex(newAttributes, geometry.attributes, x);
          }
          newIndices.push(i);
        }

        if (
          currentIndex + indicesPerPrimitive >=
          CesiumMath.SIXTY_FOUR_KILOBYTES
        ) {
          geometries.push(
            new Geometry({
              attributes: newAttributes,
              indices: newIndices,
              primitiveType: geometry.primitiveType,
              boundingSphere: geometry.boundingSphere,
              boundingSphereCV: geometry.boundingSphereCV,
            })
          );

          // Reset for next vertex-array
          oldToNewIndex = [];
          newIndices = [];
          currentIndex = 0;
          newAttributes = copyAttributesDescriptions(geometry.attributes);
        }
      }

      if (newIndices.length !== 0) {
        geometries.push(
          new Geometry({
            attributes: newAttributes,
            indices: newIndices,
            primitiveType: geometry.primitiveType,
            boundingSphere: geometry.boundingSphere,
            boundingSphereCV: geometry.boundingSphereCV,
          })
        );
      }
    } else {
      // No need to split into multiple geometries
      geometries.push(geometry);
    }

    return geometries;
  };

  var scratchProjectTo2DCartesian3 = new Cartesian3();
  var scratchProjectTo2DCartographic = new Cartographic();

  /**
   * Projects a geometry's 3D <code>position</code> attribute to 2D, replacing the <code>position</code>
   * attribute with separate <code>position3D</code> and <code>position2D</code> attributes.
   * <p>
   * If the geometry does not have a <code>position</code>, this function has no effect.
   * </p>
   *
   * @param {Geometry} geometry The geometry to modify.
   * @param {String} attributeName The name of the attribute.
   * @param {String} attributeName3D The name of the attribute in 3D.
   * @param {String} attributeName2D The name of the attribute in 2D.
   * @param {Object} [projection=new GeographicProjection()] The projection to use.
   * @returns {Geometry} The modified <code>geometry</code> argument with <code>position3D</code> and <code>position2D</code> attributes.
   *
   * @exception {DeveloperError} geometry must have attribute matching the attributeName argument.
   * @exception {DeveloperError} The attribute componentDatatype must be ComponentDatatype.DOUBLE.
   * @exception {DeveloperError} Could not project a point to 2D.
   *
   * @example
   * geometry = Cesium.GeometryPipeline.projectTo2D(geometry, 'position', 'position3D', 'position2D');
   */
  GeometryPipeline.projectTo2D = function (
    geometry,
    attributeName,
    attributeName3D,
    attributeName2D,
    projection
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    if (!defined(attributeName)) {
      throw new DeveloperError("attributeName is required.");
    }
    if (!defined(attributeName3D)) {
      throw new DeveloperError("attributeName3D is required.");
    }
    if (!defined(attributeName2D)) {
      throw new DeveloperError("attributeName2D is required.");
    }
    if (!defined(geometry.attributes[attributeName])) {
      throw new DeveloperError(
        "geometry must have attribute matching the attributeName argument: " +
          attributeName +
          "."
      );
    }
    if (
      geometry.attributes[attributeName].componentDatatype !==
      ComponentDatatype$1.DOUBLE
    ) {
      throw new DeveloperError(
        "The attribute componentDatatype must be ComponentDatatype.DOUBLE."
      );
    }
    //>>includeEnd('debug');

    var attribute = geometry.attributes[attributeName];
    projection = defined(projection) ? projection : new GeographicProjection();
    var ellipsoid = projection.ellipsoid;

    // Project original values to 2D.
    var values3D = attribute.values;
    var projectedValues = new Float64Array(values3D.length);
    var index = 0;

    for (var i = 0; i < values3D.length; i += 3) {
      var value = Cartesian3.fromArray(values3D, i, scratchProjectTo2DCartesian3);

      var lonLat = ellipsoid.cartesianToCartographic(
        value,
        scratchProjectTo2DCartographic
      );
      //>>includeStart('debug', pragmas.debug);
      if (!defined(lonLat)) {
        throw new DeveloperError(
          "Could not project point (" +
            value.x +
            ", " +
            value.y +
            ", " +
            value.z +
            ") to 2D."
        );
      }
      //>>includeEnd('debug');

      var projectedLonLat = projection.project(
        lonLat,
        scratchProjectTo2DCartesian3
      );

      projectedValues[index++] = projectedLonLat.x;
      projectedValues[index++] = projectedLonLat.y;
      projectedValues[index++] = projectedLonLat.z;
    }

    // Rename original cartesians to WGS84 cartesians.
    geometry.attributes[attributeName3D] = attribute;

    // Replace original cartesians with 2D projected cartesians
    geometry.attributes[attributeName2D] = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: projectedValues,
    });
    delete geometry.attributes[attributeName];

    return geometry;
  };

  var encodedResult = {
    high: 0.0,
    low: 0.0,
  };

  /**
   * Encodes floating-point geometry attribute values as two separate attributes to improve
   * rendering precision.
   * <p>
   * This is commonly used to create high-precision position vertex attributes.
   * </p>
   *
   * @param {Geometry} geometry The geometry to modify.
   * @param {String} attributeName The name of the attribute.
   * @param {String} attributeHighName The name of the attribute for the encoded high bits.
   * @param {String} attributeLowName The name of the attribute for the encoded low bits.
   * @returns {Geometry} The modified <code>geometry</code> argument, with its encoded attribute.
   *
   * @exception {DeveloperError} geometry must have attribute matching the attributeName argument.
   * @exception {DeveloperError} The attribute componentDatatype must be ComponentDatatype.DOUBLE.
   *
   * @example
   * geometry = Cesium.GeometryPipeline.encodeAttribute(geometry, 'position3D', 'position3DHigh', 'position3DLow');
   */
  GeometryPipeline.encodeAttribute = function (
    geometry,
    attributeName,
    attributeHighName,
    attributeLowName
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    if (!defined(attributeName)) {
      throw new DeveloperError("attributeName is required.");
    }
    if (!defined(attributeHighName)) {
      throw new DeveloperError("attributeHighName is required.");
    }
    if (!defined(attributeLowName)) {
      throw new DeveloperError("attributeLowName is required.");
    }
    if (!defined(geometry.attributes[attributeName])) {
      throw new DeveloperError(
        "geometry must have attribute matching the attributeName argument: " +
          attributeName +
          "."
      );
    }
    if (
      geometry.attributes[attributeName].componentDatatype !==
      ComponentDatatype$1.DOUBLE
    ) {
      throw new DeveloperError(
        "The attribute componentDatatype must be ComponentDatatype.DOUBLE."
      );
    }
    //>>includeEnd('debug');

    var attribute = geometry.attributes[attributeName];
    var values = attribute.values;
    var length = values.length;
    var highValues = new Float32Array(length);
    var lowValues = new Float32Array(length);

    for (var i = 0; i < length; ++i) {
      EncodedCartesian3.encode(values[i], encodedResult);
      highValues[i] = encodedResult.high;
      lowValues[i] = encodedResult.low;
    }

    var componentsPerAttribute = attribute.componentsPerAttribute;

    geometry.attributes[attributeHighName] = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: componentsPerAttribute,
      values: highValues,
    });
    geometry.attributes[attributeLowName] = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: componentsPerAttribute,
      values: lowValues,
    });
    delete geometry.attributes[attributeName];

    return geometry;
  };

  var scratchCartesian3$4 = new Cartesian3();

  function transformPoint(matrix, attribute) {
    if (defined(attribute)) {
      var values = attribute.values;
      var length = values.length;
      for (var i = 0; i < length; i += 3) {
        Cartesian3.unpack(values, i, scratchCartesian3$4);
        Matrix4.multiplyByPoint(matrix, scratchCartesian3$4, scratchCartesian3$4);
        Cartesian3.pack(scratchCartesian3$4, values, i);
      }
    }
  }

  function transformVector(matrix, attribute) {
    if (defined(attribute)) {
      var values = attribute.values;
      var length = values.length;
      for (var i = 0; i < length; i += 3) {
        Cartesian3.unpack(values, i, scratchCartesian3$4);
        Matrix3.multiplyByVector(matrix, scratchCartesian3$4, scratchCartesian3$4);
        scratchCartesian3$4 = Cartesian3.normalize(
          scratchCartesian3$4,
          scratchCartesian3$4
        );
        Cartesian3.pack(scratchCartesian3$4, values, i);
      }
    }
  }

  var inverseTranspose = new Matrix4();
  var normalMatrix = new Matrix3();

  /**
   * Transforms a geometry instance to world coordinates.  This changes
   * the instance's <code>modelMatrix</code> to {@link Matrix4.IDENTITY} and transforms the
   * following attributes if they are present: <code>position</code>, <code>normal</code>,
   * <code>tangent</code>, and <code>bitangent</code>.
   *
   * @param {GeometryInstance} instance The geometry instance to modify.
   * @returns {GeometryInstance} The modified <code>instance</code> argument, with its attributes transforms to world coordinates.
   *
   * @example
   * Cesium.GeometryPipeline.transformToWorldCoordinates(instance);
   */
  GeometryPipeline.transformToWorldCoordinates = function (instance) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(instance)) {
      throw new DeveloperError("instance is required.");
    }
    //>>includeEnd('debug');

    var modelMatrix = instance.modelMatrix;

    if (Matrix4.equals(modelMatrix, Matrix4.IDENTITY)) {
      // Already in world coordinates
      return instance;
    }

    var attributes = instance.geometry.attributes;

    // Transform attributes in known vertex formats
    transformPoint(modelMatrix, attributes.position);
    transformPoint(modelMatrix, attributes.prevPosition);
    transformPoint(modelMatrix, attributes.nextPosition);

    if (
      defined(attributes.normal) ||
      defined(attributes.tangent) ||
      defined(attributes.bitangent)
    ) {
      Matrix4.inverse(modelMatrix, inverseTranspose);
      Matrix4.transpose(inverseTranspose, inverseTranspose);
      Matrix4.getMatrix3(inverseTranspose, normalMatrix);

      transformVector(normalMatrix, attributes.normal);
      transformVector(normalMatrix, attributes.tangent);
      transformVector(normalMatrix, attributes.bitangent);
    }

    var boundingSphere = instance.geometry.boundingSphere;
    if (defined(boundingSphere)) {
      instance.geometry.boundingSphere = BoundingSphere.transform(
        boundingSphere,
        modelMatrix,
        boundingSphere
      );
    }

    instance.modelMatrix = Matrix4.clone(Matrix4.IDENTITY);

    return instance;
  };

  function findAttributesInAllGeometries(instances, propertyName) {
    var length = instances.length;

    var attributesInAllGeometries = {};

    var attributes0 = instances[0][propertyName].attributes;
    var name;

    for (name in attributes0) {
      if (
        attributes0.hasOwnProperty(name) &&
        defined(attributes0[name]) &&
        defined(attributes0[name].values)
      ) {
        var attribute = attributes0[name];
        var numberOfComponents = attribute.values.length;
        var inAllGeometries = true;

        // Does this same attribute exist in all geometries?
        for (var i = 1; i < length; ++i) {
          var otherAttribute = instances[i][propertyName].attributes[name];

          if (
            !defined(otherAttribute) ||
            attribute.componentDatatype !== otherAttribute.componentDatatype ||
            attribute.componentsPerAttribute !==
              otherAttribute.componentsPerAttribute ||
            attribute.normalize !== otherAttribute.normalize
          ) {
            inAllGeometries = false;
            break;
          }

          numberOfComponents += otherAttribute.values.length;
        }

        if (inAllGeometries) {
          attributesInAllGeometries[name] = new GeometryAttribute({
            componentDatatype: attribute.componentDatatype,
            componentsPerAttribute: attribute.componentsPerAttribute,
            normalize: attribute.normalize,
            values: ComponentDatatype$1.createTypedArray(
              attribute.componentDatatype,
              numberOfComponents
            ),
          });
        }
      }
    }

    return attributesInAllGeometries;
  }

  var tempScratch = new Cartesian3();

  function combineGeometries(instances, propertyName) {
    var length = instances.length;

    var name;
    var i;
    var j;
    var k;

    var m = instances[0].modelMatrix;
    var haveIndices = defined(instances[0][propertyName].indices);
    var primitiveType = instances[0][propertyName].primitiveType;

    //>>includeStart('debug', pragmas.debug);
    for (i = 1; i < length; ++i) {
      if (!Matrix4.equals(instances[i].modelMatrix, m)) {
        throw new DeveloperError("All instances must have the same modelMatrix.");
      }
      if (defined(instances[i][propertyName].indices) !== haveIndices) {
        throw new DeveloperError(
          "All instance geometries must have an indices or not have one."
        );
      }
      if (instances[i][propertyName].primitiveType !== primitiveType) {
        throw new DeveloperError(
          "All instance geometries must have the same primitiveType."
        );
      }
    }
    //>>includeEnd('debug');

    // Find subset of attributes in all geometries
    var attributes = findAttributesInAllGeometries(instances, propertyName);
    var values;
    var sourceValues;
    var sourceValuesLength;

    // Combine attributes from each geometry into a single typed array
    for (name in attributes) {
      if (attributes.hasOwnProperty(name)) {
        values = attributes[name].values;

        k = 0;
        for (i = 0; i < length; ++i) {
          sourceValues = instances[i][propertyName].attributes[name].values;
          sourceValuesLength = sourceValues.length;

          for (j = 0; j < sourceValuesLength; ++j) {
            values[k++] = sourceValues[j];
          }
        }
      }
    }

    // Combine index lists
    var indices;

    if (haveIndices) {
      var numberOfIndices = 0;
      for (i = 0; i < length; ++i) {
        numberOfIndices += instances[i][propertyName].indices.length;
      }

      var numberOfVertices = Geometry.computeNumberOfVertices(
        new Geometry({
          attributes: attributes,
          primitiveType: PrimitiveType$1.POINTS,
        })
      );
      var destIndices = IndexDatatype$1.createTypedArray(
        numberOfVertices,
        numberOfIndices
      );

      var destOffset = 0;
      var offset = 0;

      for (i = 0; i < length; ++i) {
        var sourceIndices = instances[i][propertyName].indices;
        var sourceIndicesLen = sourceIndices.length;

        for (k = 0; k < sourceIndicesLen; ++k) {
          destIndices[destOffset++] = offset + sourceIndices[k];
        }

        offset += Geometry.computeNumberOfVertices(instances[i][propertyName]);
      }

      indices = destIndices;
    }

    // Create bounding sphere that includes all instances
    var center = new Cartesian3();
    var radius = 0.0;
    var bs;

    for (i = 0; i < length; ++i) {
      bs = instances[i][propertyName].boundingSphere;
      if (!defined(bs)) {
        // If any geometries have an undefined bounding sphere, then so does the combined geometry
        center = undefined;
        break;
      }

      Cartesian3.add(bs.center, center, center);
    }

    if (defined(center)) {
      Cartesian3.divideByScalar(center, length, center);

      for (i = 0; i < length; ++i) {
        bs = instances[i][propertyName].boundingSphere;
        var tempRadius =
          Cartesian3.magnitude(
            Cartesian3.subtract(bs.center, center, tempScratch)
          ) + bs.radius;

        if (tempRadius > radius) {
          radius = tempRadius;
        }
      }
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: primitiveType,
      boundingSphere: defined(center)
        ? new BoundingSphere(center, radius)
        : undefined,
    });
  }

  /**
   * Combines geometry from several {@link GeometryInstance} objects into one geometry.
   * This concatenates the attributes, concatenates and adjusts the indices, and creates
   * a bounding sphere encompassing all instances.
   * <p>
   * If the instances do not have the same attributes, a subset of attributes common
   * to all instances is used, and the others are ignored.
   * </p>
   * <p>
   * This is used by {@link Primitive} to efficiently render a large amount of static data.
   * </p>
   *
   * @private
   *
   * @param {GeometryInstance[]} [instances] The array of {@link GeometryInstance} objects whose geometry will be combined.
   * @returns {Geometry} A single geometry created from the provided geometry instances.
   *
   * @exception {DeveloperError} All instances must have the same modelMatrix.
   * @exception {DeveloperError} All instance geometries must have an indices or not have one.
   * @exception {DeveloperError} All instance geometries must have the same primitiveType.
   *
   *
   * @example
   * for (var i = 0; i < instances.length; ++i) {
   *   Cesium.GeometryPipeline.transformToWorldCoordinates(instances[i]);
   * }
   * var geometries = Cesium.GeometryPipeline.combineInstances(instances);
   *
   * @see GeometryPipeline.transformToWorldCoordinates
   */
  GeometryPipeline.combineInstances = function (instances) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(instances) || instances.length < 1) {
      throw new DeveloperError(
        "instances is required and must have length greater than zero."
      );
    }
    //>>includeEnd('debug');

    var instanceGeometry = [];
    var instanceSplitGeometry = [];
    var length = instances.length;
    for (var i = 0; i < length; ++i) {
      var instance = instances[i];

      if (defined(instance.geometry)) {
        instanceGeometry.push(instance);
      } else if (
        defined(instance.westHemisphereGeometry) &&
        defined(instance.eastHemisphereGeometry)
      ) {
        instanceSplitGeometry.push(instance);
      }
    }

    var geometries = [];
    if (instanceGeometry.length > 0) {
      geometries.push(combineGeometries(instanceGeometry, "geometry"));
    }

    if (instanceSplitGeometry.length > 0) {
      geometries.push(
        combineGeometries(instanceSplitGeometry, "westHemisphereGeometry")
      );
      geometries.push(
        combineGeometries(instanceSplitGeometry, "eastHemisphereGeometry")
      );
    }

    return geometries;
  };

  var normal = new Cartesian3();
  var v0 = new Cartesian3();
  var v1 = new Cartesian3();
  var v2 = new Cartesian3();

  /**
   * Computes per-vertex normals for a geometry containing <code>TRIANGLES</code> by averaging the normals of
   * all triangles incident to the vertex.  The result is a new <code>normal</code> attribute added to the geometry.
   * This assumes a counter-clockwise winding order.
   *
   * @param {Geometry} geometry The geometry to modify.
   * @returns {Geometry} The modified <code>geometry</code> argument with the computed <code>normal</code> attribute.
   *
   * @exception {DeveloperError} geometry.indices length must be greater than 0 and be a multiple of 3.
   * @exception {DeveloperError} geometry.primitiveType must be {@link PrimitiveType.TRIANGLES}.
   *
   * @example
   * Cesium.GeometryPipeline.computeNormal(geometry);
   */
  GeometryPipeline.computeNormal = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    if (
      !defined(geometry.attributes.position) ||
      !defined(geometry.attributes.position.values)
    ) {
      throw new DeveloperError(
        "geometry.attributes.position.values is required."
      );
    }
    if (!defined(geometry.indices)) {
      throw new DeveloperError("geometry.indices is required.");
    }
    if (geometry.indices.length < 2 || geometry.indices.length % 3 !== 0) {
      throw new DeveloperError(
        "geometry.indices length must be greater than 0 and be a multiple of 3."
      );
    }
    if (geometry.primitiveType !== PrimitiveType$1.TRIANGLES) {
      throw new DeveloperError(
        "geometry.primitiveType must be PrimitiveType.TRIANGLES."
      );
    }
    //>>includeEnd('debug');

    var indices = geometry.indices;
    var attributes = geometry.attributes;
    var vertices = attributes.position.values;
    var numVertices = attributes.position.values.length / 3;
    var numIndices = indices.length;
    var normalsPerVertex = new Array(numVertices);
    var normalsPerTriangle = new Array(numIndices / 3);
    var normalIndices = new Array(numIndices);
    var i;
    for (i = 0; i < numVertices; i++) {
      normalsPerVertex[i] = {
        indexOffset: 0,
        count: 0,
        currentCount: 0,
      };
    }

    var j = 0;
    for (i = 0; i < numIndices; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];
      var i03 = i0 * 3;
      var i13 = i1 * 3;
      var i23 = i2 * 3;

      v0.x = vertices[i03];
      v0.y = vertices[i03 + 1];
      v0.z = vertices[i03 + 2];
      v1.x = vertices[i13];
      v1.y = vertices[i13 + 1];
      v1.z = vertices[i13 + 2];
      v2.x = vertices[i23];
      v2.y = vertices[i23 + 1];
      v2.z = vertices[i23 + 2];

      normalsPerVertex[i0].count++;
      normalsPerVertex[i1].count++;
      normalsPerVertex[i2].count++;

      Cartesian3.subtract(v1, v0, v1);
      Cartesian3.subtract(v2, v0, v2);
      normalsPerTriangle[j] = Cartesian3.cross(v1, v2, new Cartesian3());
      j++;
    }

    var indexOffset = 0;
    for (i = 0; i < numVertices; i++) {
      normalsPerVertex[i].indexOffset += indexOffset;
      indexOffset += normalsPerVertex[i].count;
    }

    j = 0;
    var vertexNormalData;
    for (i = 0; i < numIndices; i += 3) {
      vertexNormalData = normalsPerVertex[indices[i]];
      var index = vertexNormalData.indexOffset + vertexNormalData.currentCount;
      normalIndices[index] = j;
      vertexNormalData.currentCount++;

      vertexNormalData = normalsPerVertex[indices[i + 1]];
      index = vertexNormalData.indexOffset + vertexNormalData.currentCount;
      normalIndices[index] = j;
      vertexNormalData.currentCount++;

      vertexNormalData = normalsPerVertex[indices[i + 2]];
      index = vertexNormalData.indexOffset + vertexNormalData.currentCount;
      normalIndices[index] = j;
      vertexNormalData.currentCount++;

      j++;
    }

    var normalValues = new Float32Array(numVertices * 3);
    for (i = 0; i < numVertices; i++) {
      var i3 = i * 3;
      vertexNormalData = normalsPerVertex[i];
      Cartesian3.clone(Cartesian3.ZERO, normal);
      if (vertexNormalData.count > 0) {
        for (j = 0; j < vertexNormalData.count; j++) {
          Cartesian3.add(
            normal,
            normalsPerTriangle[normalIndices[vertexNormalData.indexOffset + j]],
            normal
          );
        }

        // We can run into an issue where a vertex is used with 2 primitives that have opposite winding order.
        if (
          Cartesian3.equalsEpsilon(Cartesian3.ZERO, normal, CesiumMath.EPSILON10)
        ) {
          Cartesian3.clone(
            normalsPerTriangle[normalIndices[vertexNormalData.indexOffset]],
            normal
          );
        }
      }

      // We end up with a zero vector probably because of a degenerate triangle
      if (
        Cartesian3.equalsEpsilon(Cartesian3.ZERO, normal, CesiumMath.EPSILON10)
      ) {
        // Default to (0,0,1)
        normal.z = 1.0;
      }

      Cartesian3.normalize(normal, normal);
      normalValues[i3] = normal.x;
      normalValues[i3 + 1] = normal.y;
      normalValues[i3 + 2] = normal.z;
    }

    geometry.attributes.normal = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      values: normalValues,
    });

    return geometry;
  };

  var normalScratch$1 = new Cartesian3();
  var normalScale = new Cartesian3();
  var tScratch = new Cartesian3();

  /**
   * Computes per-vertex tangents and bitangents for a geometry containing <code>TRIANGLES</code>.
   * The result is new <code>tangent</code> and <code>bitangent</code> attributes added to the geometry.
   * This assumes a counter-clockwise winding order.
   * <p>
   * Based on <a href="http://www.terathon.com/code/tangent.html">Computing Tangent Space Basis Vectors
   * for an Arbitrary Mesh</a> by Eric Lengyel.
   * </p>
   *
   * @param {Geometry} geometry The geometry to modify.
   * @returns {Geometry} The modified <code>geometry</code> argument with the computed <code>tangent</code> and <code>bitangent</code> attributes.
   *
   * @exception {DeveloperError} geometry.indices length must be greater than 0 and be a multiple of 3.
   * @exception {DeveloperError} geometry.primitiveType must be {@link PrimitiveType.TRIANGLES}.
   *
   * @example
   * Cesium.GeometryPipeline.computeTangentAndBiTangent(geometry);
   */
  GeometryPipeline.computeTangentAndBitangent = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    //>>includeEnd('debug');

    var attributes = geometry.attributes;
    var indices = geometry.indices;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(attributes.position) || !defined(attributes.position.values)) {
      throw new DeveloperError(
        "geometry.attributes.position.values is required."
      );
    }
    if (!defined(attributes.normal) || !defined(attributes.normal.values)) {
      throw new DeveloperError("geometry.attributes.normal.values is required.");
    }
    if (!defined(attributes.st) || !defined(attributes.st.values)) {
      throw new DeveloperError("geometry.attributes.st.values is required.");
    }
    if (!defined(indices)) {
      throw new DeveloperError("geometry.indices is required.");
    }
    if (indices.length < 2 || indices.length % 3 !== 0) {
      throw new DeveloperError(
        "geometry.indices length must be greater than 0 and be a multiple of 3."
      );
    }
    if (geometry.primitiveType !== PrimitiveType$1.TRIANGLES) {
      throw new DeveloperError(
        "geometry.primitiveType must be PrimitiveType.TRIANGLES."
      );
    }
    //>>includeEnd('debug');

    var vertices = geometry.attributes.position.values;
    var normals = geometry.attributes.normal.values;
    var st = geometry.attributes.st.values;

    var numVertices = geometry.attributes.position.values.length / 3;
    var numIndices = indices.length;
    var tan1 = new Array(numVertices * 3);

    var i;
    for (i = 0; i < tan1.length; i++) {
      tan1[i] = 0;
    }

    var i03;
    var i13;
    var i23;
    for (i = 0; i < numIndices; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];
      i03 = i0 * 3;
      i13 = i1 * 3;
      i23 = i2 * 3;
      var i02 = i0 * 2;
      var i12 = i1 * 2;
      var i22 = i2 * 2;

      var ux = vertices[i03];
      var uy = vertices[i03 + 1];
      var uz = vertices[i03 + 2];

      var wx = st[i02];
      var wy = st[i02 + 1];
      var t1 = st[i12 + 1] - wy;
      var t2 = st[i22 + 1] - wy;

      var r = 1.0 / ((st[i12] - wx) * t2 - (st[i22] - wx) * t1);
      var sdirx = (t2 * (vertices[i13] - ux) - t1 * (vertices[i23] - ux)) * r;
      var sdiry =
        (t2 * (vertices[i13 + 1] - uy) - t1 * (vertices[i23 + 1] - uy)) * r;
      var sdirz =
        (t2 * (vertices[i13 + 2] - uz) - t1 * (vertices[i23 + 2] - uz)) * r;

      tan1[i03] += sdirx;
      tan1[i03 + 1] += sdiry;
      tan1[i03 + 2] += sdirz;

      tan1[i13] += sdirx;
      tan1[i13 + 1] += sdiry;
      tan1[i13 + 2] += sdirz;

      tan1[i23] += sdirx;
      tan1[i23 + 1] += sdiry;
      tan1[i23 + 2] += sdirz;
    }

    var tangentValues = new Float32Array(numVertices * 3);
    var bitangentValues = new Float32Array(numVertices * 3);

    for (i = 0; i < numVertices; i++) {
      i03 = i * 3;
      i13 = i03 + 1;
      i23 = i03 + 2;

      var n = Cartesian3.fromArray(normals, i03, normalScratch$1);
      var t = Cartesian3.fromArray(tan1, i03, tScratch);
      var scalar = Cartesian3.dot(n, t);
      Cartesian3.multiplyByScalar(n, scalar, normalScale);
      Cartesian3.normalize(Cartesian3.subtract(t, normalScale, t), t);

      tangentValues[i03] = t.x;
      tangentValues[i13] = t.y;
      tangentValues[i23] = t.z;

      Cartesian3.normalize(Cartesian3.cross(n, t, t), t);

      bitangentValues[i03] = t.x;
      bitangentValues[i13] = t.y;
      bitangentValues[i23] = t.z;
    }

    geometry.attributes.tangent = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      values: tangentValues,
    });

    geometry.attributes.bitangent = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      values: bitangentValues,
    });

    return geometry;
  };

  var scratchCartesian2$3 = new Cartesian2();
  var toEncode1 = new Cartesian3();
  var toEncode2 = new Cartesian3();
  var toEncode3 = new Cartesian3();
  var encodeResult2 = new Cartesian2();
  /**
   * Compresses and packs geometry normal attribute values to save memory.
   *
   * @param {Geometry} geometry The geometry to modify.
   * @returns {Geometry} The modified <code>geometry</code> argument, with its normals compressed and packed.
   *
   * @example
   * geometry = Cesium.GeometryPipeline.compressVertices(geometry);
   */
  GeometryPipeline.compressVertices = function (geometry) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("geometry is required.");
    }
    //>>includeEnd('debug');

    var extrudeAttribute = geometry.attributes.extrudeDirection;
    var i;
    var numVertices;
    if (defined(extrudeAttribute)) {
      //only shadow volumes use extrudeDirection, and shadow volumes use vertexFormat: POSITION_ONLY so we don't need to check other attributes
      var extrudeDirections = extrudeAttribute.values;
      numVertices = extrudeDirections.length / 3.0;
      var compressedDirections = new Float32Array(numVertices * 2);

      var i2 = 0;
      for (i = 0; i < numVertices; ++i) {
        Cartesian3.fromArray(extrudeDirections, i * 3.0, toEncode1);
        if (Cartesian3.equals(toEncode1, Cartesian3.ZERO)) {
          i2 += 2;
          continue;
        }
        encodeResult2 = AttributeCompression.octEncodeInRange(
          toEncode1,
          65535,
          encodeResult2
        );
        compressedDirections[i2++] = encodeResult2.x;
        compressedDirections[i2++] = encodeResult2.y;
      }

      geometry.attributes.compressedAttributes = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: compressedDirections,
      });
      delete geometry.attributes.extrudeDirection;
      return geometry;
    }

    var normalAttribute = geometry.attributes.normal;
    var stAttribute = geometry.attributes.st;

    var hasNormal = defined(normalAttribute);
    var hasSt = defined(stAttribute);
    if (!hasNormal && !hasSt) {
      return geometry;
    }

    var tangentAttribute = geometry.attributes.tangent;
    var bitangentAttribute = geometry.attributes.bitangent;

    var hasTangent = defined(tangentAttribute);
    var hasBitangent = defined(bitangentAttribute);

    var normals;
    var st;
    var tangents;
    var bitangents;

    if (hasNormal) {
      normals = normalAttribute.values;
    }
    if (hasSt) {
      st = stAttribute.values;
    }
    if (hasTangent) {
      tangents = tangentAttribute.values;
    }
    if (hasBitangent) {
      bitangents = bitangentAttribute.values;
    }

    var length = hasNormal ? normals.length : st.length;
    var numComponents = hasNormal ? 3.0 : 2.0;
    numVertices = length / numComponents;

    var compressedLength = numVertices;
    var numCompressedComponents = hasSt && hasNormal ? 2.0 : 1.0;
    numCompressedComponents += hasTangent || hasBitangent ? 1.0 : 0.0;
    compressedLength *= numCompressedComponents;

    var compressedAttributes = new Float32Array(compressedLength);

    var normalIndex = 0;
    for (i = 0; i < numVertices; ++i) {
      if (hasSt) {
        Cartesian2.fromArray(st, i * 2.0, scratchCartesian2$3);
        compressedAttributes[
          normalIndex++
        ] = AttributeCompression.compressTextureCoordinates(scratchCartesian2$3);
      }

      var index = i * 3.0;
      if (hasNormal && defined(tangents) && defined(bitangents)) {
        Cartesian3.fromArray(normals, index, toEncode1);
        Cartesian3.fromArray(tangents, index, toEncode2);
        Cartesian3.fromArray(bitangents, index, toEncode3);

        AttributeCompression.octPack(
          toEncode1,
          toEncode2,
          toEncode3,
          scratchCartesian2$3
        );
        compressedAttributes[normalIndex++] = scratchCartesian2$3.x;
        compressedAttributes[normalIndex++] = scratchCartesian2$3.y;
      } else {
        if (hasNormal) {
          Cartesian3.fromArray(normals, index, toEncode1);
          compressedAttributes[
            normalIndex++
          ] = AttributeCompression.octEncodeFloat(toEncode1);
        }

        if (hasTangent) {
          Cartesian3.fromArray(tangents, index, toEncode1);
          compressedAttributes[
            normalIndex++
          ] = AttributeCompression.octEncodeFloat(toEncode1);
        }

        if (hasBitangent) {
          Cartesian3.fromArray(bitangents, index, toEncode1);
          compressedAttributes[
            normalIndex++
          ] = AttributeCompression.octEncodeFloat(toEncode1);
        }
      }
    }

    geometry.attributes.compressedAttributes = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: numCompressedComponents,
      values: compressedAttributes,
    });

    if (hasNormal) {
      delete geometry.attributes.normal;
    }
    if (hasSt) {
      delete geometry.attributes.st;
    }
    if (hasBitangent) {
      delete geometry.attributes.bitangent;
    }
    if (hasTangent) {
      delete geometry.attributes.tangent;
    }

    return geometry;
  };

  function indexTriangles(geometry) {
    if (defined(geometry.indices)) {
      return geometry;
    }
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);

    //>>includeStart('debug', pragmas.debug);
    if (numberOfVertices < 3) {
      throw new DeveloperError("The number of vertices must be at least three.");
    }
    if (numberOfVertices % 3 !== 0) {
      throw new DeveloperError(
        "The number of vertices must be a multiple of three."
      );
    }
    //>>includeEnd('debug');

    var indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      numberOfVertices
    );
    for (var i = 0; i < numberOfVertices; ++i) {
      indices[i] = i;
    }

    geometry.indices = indices;
    return geometry;
  }

  function indexTriangleFan(geometry) {
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);

    //>>includeStart('debug', pragmas.debug);
    if (numberOfVertices < 3) {
      throw new DeveloperError("The number of vertices must be at least three.");
    }
    //>>includeEnd('debug');

    var indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      (numberOfVertices - 2) * 3
    );
    indices[0] = 1;
    indices[1] = 0;
    indices[2] = 2;

    var indicesIndex = 3;
    for (var i = 3; i < numberOfVertices; ++i) {
      indices[indicesIndex++] = i - 1;
      indices[indicesIndex++] = 0;
      indices[indicesIndex++] = i;
    }

    geometry.indices = indices;
    geometry.primitiveType = PrimitiveType$1.TRIANGLES;
    return geometry;
  }

  function indexTriangleStrip(geometry) {
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);

    //>>includeStart('debug', pragmas.debug);
    if (numberOfVertices < 3) {
      throw new DeveloperError("The number of vertices must be at least 3.");
    }
    //>>includeEnd('debug');

    var indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      (numberOfVertices - 2) * 3
    );
    indices[0] = 0;
    indices[1] = 1;
    indices[2] = 2;

    if (numberOfVertices > 3) {
      indices[3] = 0;
      indices[4] = 2;
      indices[5] = 3;
    }

    var indicesIndex = 6;
    for (var i = 3; i < numberOfVertices - 1; i += 2) {
      indices[indicesIndex++] = i;
      indices[indicesIndex++] = i - 1;
      indices[indicesIndex++] = i + 1;

      if (i + 2 < numberOfVertices) {
        indices[indicesIndex++] = i;
        indices[indicesIndex++] = i + 1;
        indices[indicesIndex++] = i + 2;
      }
    }

    geometry.indices = indices;
    geometry.primitiveType = PrimitiveType$1.TRIANGLES;
    return geometry;
  }

  function indexLines(geometry) {
    if (defined(geometry.indices)) {
      return geometry;
    }
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);

    //>>includeStart('debug', pragmas.debug);
    if (numberOfVertices < 2) {
      throw new DeveloperError("The number of vertices must be at least two.");
    }
    if (numberOfVertices % 2 !== 0) {
      throw new DeveloperError("The number of vertices must be a multiple of 2.");
    }
    //>>includeEnd('debug');

    var indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      numberOfVertices
    );
    for (var i = 0; i < numberOfVertices; ++i) {
      indices[i] = i;
    }

    geometry.indices = indices;
    return geometry;
  }

  function indexLineStrip(geometry) {
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);

    //>>includeStart('debug', pragmas.debug);
    if (numberOfVertices < 2) {
      throw new DeveloperError("The number of vertices must be at least two.");
    }
    //>>includeEnd('debug');

    var indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      (numberOfVertices - 1) * 2
    );
    indices[0] = 0;
    indices[1] = 1;
    var indicesIndex = 2;
    for (var i = 2; i < numberOfVertices; ++i) {
      indices[indicesIndex++] = i - 1;
      indices[indicesIndex++] = i;
    }

    geometry.indices = indices;
    geometry.primitiveType = PrimitiveType$1.LINES;
    return geometry;
  }

  function indexLineLoop(geometry) {
    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);

    //>>includeStart('debug', pragmas.debug);
    if (numberOfVertices < 2) {
      throw new DeveloperError("The number of vertices must be at least two.");
    }
    //>>includeEnd('debug');

    var indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      numberOfVertices * 2
    );

    indices[0] = 0;
    indices[1] = 1;

    var indicesIndex = 2;
    for (var i = 2; i < numberOfVertices; ++i) {
      indices[indicesIndex++] = i - 1;
      indices[indicesIndex++] = i;
    }

    indices[indicesIndex++] = numberOfVertices - 1;
    indices[indicesIndex] = 0;

    geometry.indices = indices;
    geometry.primitiveType = PrimitiveType$1.LINES;
    return geometry;
  }

  function indexPrimitive(geometry) {
    switch (geometry.primitiveType) {
      case PrimitiveType$1.TRIANGLE_FAN:
        return indexTriangleFan(geometry);
      case PrimitiveType$1.TRIANGLE_STRIP:
        return indexTriangleStrip(geometry);
      case PrimitiveType$1.TRIANGLES:
        return indexTriangles(geometry);
      case PrimitiveType$1.LINE_STRIP:
        return indexLineStrip(geometry);
      case PrimitiveType$1.LINE_LOOP:
        return indexLineLoop(geometry);
      case PrimitiveType$1.LINES:
        return indexLines(geometry);
    }

    return geometry;
  }

  function offsetPointFromXZPlane(p, isBehind) {
    if (Math.abs(p.y) < CesiumMath.EPSILON6) {
      if (isBehind) {
        p.y = -CesiumMath.EPSILON6;
      } else {
        p.y = CesiumMath.EPSILON6;
      }
    }
  }

  function offsetTriangleFromXZPlane(p0, p1, p2) {
    if (p0.y !== 0.0 && p1.y !== 0.0 && p2.y !== 0.0) {
      offsetPointFromXZPlane(p0, p0.y < 0.0);
      offsetPointFromXZPlane(p1, p1.y < 0.0);
      offsetPointFromXZPlane(p2, p2.y < 0.0);
      return;
    }

    var p0y = Math.abs(p0.y);
    var p1y = Math.abs(p1.y);
    var p2y = Math.abs(p2.y);

    var sign;
    if (p0y > p1y) {
      if (p0y > p2y) {
        sign = CesiumMath.sign(p0.y);
      } else {
        sign = CesiumMath.sign(p2.y);
      }
    } else if (p1y > p2y) {
      sign = CesiumMath.sign(p1.y);
    } else {
      sign = CesiumMath.sign(p2.y);
    }

    var isBehind = sign < 0.0;
    offsetPointFromXZPlane(p0, isBehind);
    offsetPointFromXZPlane(p1, isBehind);
    offsetPointFromXZPlane(p2, isBehind);
  }

  var c3 = new Cartesian3();
  function getXZIntersectionOffsetPoints(p, p1, u1, v1) {
    Cartesian3.add(
      p,
      Cartesian3.multiplyByScalar(
        Cartesian3.subtract(p1, p, c3),
        p.y / (p.y - p1.y),
        c3
      ),
      u1
    );
    Cartesian3.clone(u1, v1);
    offsetPointFromXZPlane(u1, true);
    offsetPointFromXZPlane(v1, false);
  }

  var u1 = new Cartesian3();
  var u2 = new Cartesian3();
  var q1 = new Cartesian3();
  var q2 = new Cartesian3();

  var splitTriangleResult = {
    positions: new Array(7),
    indices: new Array(3 * 3),
  };

  function splitTriangle(p0, p1, p2) {
    // In WGS84 coordinates, for a triangle approximately on the
    // ellipsoid to cross the IDL, first it needs to be on the
    // negative side of the plane x = 0.
    if (p0.x >= 0.0 || p1.x >= 0.0 || p2.x >= 0.0) {
      return undefined;
    }

    offsetTriangleFromXZPlane(p0, p1, p2);

    var p0Behind = p0.y < 0.0;
    var p1Behind = p1.y < 0.0;
    var p2Behind = p2.y < 0.0;

    var numBehind = 0;
    numBehind += p0Behind ? 1 : 0;
    numBehind += p1Behind ? 1 : 0;
    numBehind += p2Behind ? 1 : 0;

    var indices = splitTriangleResult.indices;

    if (numBehind === 1) {
      indices[1] = 3;
      indices[2] = 4;
      indices[5] = 6;
      indices[7] = 6;
      indices[8] = 5;

      if (p0Behind) {
        getXZIntersectionOffsetPoints(p0, p1, u1, q1);
        getXZIntersectionOffsetPoints(p0, p2, u2, q2);

        indices[0] = 0;
        indices[3] = 1;
        indices[4] = 2;
        indices[6] = 1;
      } else if (p1Behind) {
        getXZIntersectionOffsetPoints(p1, p2, u1, q1);
        getXZIntersectionOffsetPoints(p1, p0, u2, q2);

        indices[0] = 1;
        indices[3] = 2;
        indices[4] = 0;
        indices[6] = 2;
      } else if (p2Behind) {
        getXZIntersectionOffsetPoints(p2, p0, u1, q1);
        getXZIntersectionOffsetPoints(p2, p1, u2, q2);

        indices[0] = 2;
        indices[3] = 0;
        indices[4] = 1;
        indices[6] = 0;
      }
    } else if (numBehind === 2) {
      indices[2] = 4;
      indices[4] = 4;
      indices[5] = 3;
      indices[7] = 5;
      indices[8] = 6;

      if (!p0Behind) {
        getXZIntersectionOffsetPoints(p0, p1, u1, q1);
        getXZIntersectionOffsetPoints(p0, p2, u2, q2);

        indices[0] = 1;
        indices[1] = 2;
        indices[3] = 1;
        indices[6] = 0;
      } else if (!p1Behind) {
        getXZIntersectionOffsetPoints(p1, p2, u1, q1);
        getXZIntersectionOffsetPoints(p1, p0, u2, q2);

        indices[0] = 2;
        indices[1] = 0;
        indices[3] = 2;
        indices[6] = 1;
      } else if (!p2Behind) {
        getXZIntersectionOffsetPoints(p2, p0, u1, q1);
        getXZIntersectionOffsetPoints(p2, p1, u2, q2);

        indices[0] = 0;
        indices[1] = 1;
        indices[3] = 0;
        indices[6] = 2;
      }
    }

    var positions = splitTriangleResult.positions;
    positions[0] = p0;
    positions[1] = p1;
    positions[2] = p2;
    positions.length = 3;

    if (numBehind === 1 || numBehind === 2) {
      positions[3] = u1;
      positions[4] = u2;
      positions[5] = q1;
      positions[6] = q2;
      positions.length = 7;
    }

    return splitTriangleResult;
  }

  function updateGeometryAfterSplit(geometry, computeBoundingSphere) {
    var attributes = geometry.attributes;

    if (attributes.position.values.length === 0) {
      return undefined;
    }

    for (var property in attributes) {
      if (
        attributes.hasOwnProperty(property) &&
        defined(attributes[property]) &&
        defined(attributes[property].values)
      ) {
        var attribute = attributes[property];
        attribute.values = ComponentDatatype$1.createTypedArray(
          attribute.componentDatatype,
          attribute.values
        );
      }
    }

    var numberOfVertices = Geometry.computeNumberOfVertices(geometry);
    geometry.indices = IndexDatatype$1.createTypedArray(
      numberOfVertices,
      geometry.indices
    );

    if (computeBoundingSphere) {
      geometry.boundingSphere = BoundingSphere.fromVertices(
        attributes.position.values
      );
    }

    return geometry;
  }

  function copyGeometryForSplit(geometry) {
    var attributes = geometry.attributes;
    var copiedAttributes = {};

    for (var property in attributes) {
      if (
        attributes.hasOwnProperty(property) &&
        defined(attributes[property]) &&
        defined(attributes[property].values)
      ) {
        var attribute = attributes[property];
        copiedAttributes[property] = new GeometryAttribute({
          componentDatatype: attribute.componentDatatype,
          componentsPerAttribute: attribute.componentsPerAttribute,
          normalize: attribute.normalize,
          values: [],
        });
      }
    }

    return new Geometry({
      attributes: copiedAttributes,
      indices: [],
      primitiveType: geometry.primitiveType,
    });
  }

  function updateInstanceAfterSplit(instance, westGeometry, eastGeometry) {
    var computeBoundingSphere = defined(instance.geometry.boundingSphere);

    westGeometry = updateGeometryAfterSplit(westGeometry, computeBoundingSphere);
    eastGeometry = updateGeometryAfterSplit(eastGeometry, computeBoundingSphere);

    if (defined(eastGeometry) && !defined(westGeometry)) {
      instance.geometry = eastGeometry;
    } else if (!defined(eastGeometry) && defined(westGeometry)) {
      instance.geometry = westGeometry;
    } else {
      instance.westHemisphereGeometry = westGeometry;
      instance.eastHemisphereGeometry = eastGeometry;
      instance.geometry = undefined;
    }
  }

  function generateBarycentricInterpolateFunction(
    CartesianType,
    numberOfComponents
  ) {
    var v0Scratch = new CartesianType();
    var v1Scratch = new CartesianType();
    var v2Scratch = new CartesianType();

    return function (
      i0,
      i1,
      i2,
      coords,
      sourceValues,
      currentValues,
      insertedIndex,
      normalize
    ) {
      var v0 = CartesianType.fromArray(
        sourceValues,
        i0 * numberOfComponents,
        v0Scratch
      );
      var v1 = CartesianType.fromArray(
        sourceValues,
        i1 * numberOfComponents,
        v1Scratch
      );
      var v2 = CartesianType.fromArray(
        sourceValues,
        i2 * numberOfComponents,
        v2Scratch
      );

      CartesianType.multiplyByScalar(v0, coords.x, v0);
      CartesianType.multiplyByScalar(v1, coords.y, v1);
      CartesianType.multiplyByScalar(v2, coords.z, v2);

      var value = CartesianType.add(v0, v1, v0);
      CartesianType.add(value, v2, value);

      if (normalize) {
        CartesianType.normalize(value, value);
      }

      CartesianType.pack(
        value,
        currentValues,
        insertedIndex * numberOfComponents
      );
    };
  }

  var interpolateAndPackCartesian4 = generateBarycentricInterpolateFunction(
    Cartesian4,
    4
  );
  var interpolateAndPackCartesian3 = generateBarycentricInterpolateFunction(
    Cartesian3,
    3
  );
  var interpolateAndPackCartesian2 = generateBarycentricInterpolateFunction(
    Cartesian2,
    2
  );
  var interpolateAndPackBoolean = function (
    i0,
    i1,
    i2,
    coords,
    sourceValues,
    currentValues,
    insertedIndex
  ) {
    var v1 = sourceValues[i0] * coords.x;
    var v2 = sourceValues[i1] * coords.y;
    var v3 = sourceValues[i2] * coords.z;
    currentValues[insertedIndex] = v1 + v2 + v3 > CesiumMath.EPSILON6 ? 1 : 0;
  };

  var p0Scratch = new Cartesian3();
  var p1Scratch = new Cartesian3();
  var p2Scratch = new Cartesian3();
  var barycentricScratch = new Cartesian3();

  function computeTriangleAttributes(
    i0,
    i1,
    i2,
    point,
    positions,
    normals,
    tangents,
    bitangents,
    texCoords,
    extrudeDirections,
    applyOffset,
    currentAttributes,
    customAttributeNames,
    customAttributesLength,
    allAttributes,
    insertedIndex
  ) {
    if (
      !defined(normals) &&
      !defined(tangents) &&
      !defined(bitangents) &&
      !defined(texCoords) &&
      !defined(extrudeDirections) &&
      customAttributesLength === 0
    ) {
      return;
    }

    var p0 = Cartesian3.fromArray(positions, i0 * 3, p0Scratch);
    var p1 = Cartesian3.fromArray(positions, i1 * 3, p1Scratch);
    var p2 = Cartesian3.fromArray(positions, i2 * 3, p2Scratch);
    var coords = barycentricCoordinates(point, p0, p1, p2, barycentricScratch);

    if (defined(normals)) {
      interpolateAndPackCartesian3(
        i0,
        i1,
        i2,
        coords,
        normals,
        currentAttributes.normal.values,
        insertedIndex,
        true
      );
    }

    if (defined(extrudeDirections)) {
      var d0 = Cartesian3.fromArray(extrudeDirections, i0 * 3, p0Scratch);
      var d1 = Cartesian3.fromArray(extrudeDirections, i1 * 3, p1Scratch);
      var d2 = Cartesian3.fromArray(extrudeDirections, i2 * 3, p2Scratch);

      Cartesian3.multiplyByScalar(d0, coords.x, d0);
      Cartesian3.multiplyByScalar(d1, coords.y, d1);
      Cartesian3.multiplyByScalar(d2, coords.z, d2);

      var direction;
      if (
        !Cartesian3.equals(d0, Cartesian3.ZERO) ||
        !Cartesian3.equals(d1, Cartesian3.ZERO) ||
        !Cartesian3.equals(d2, Cartesian3.ZERO)
      ) {
        direction = Cartesian3.add(d0, d1, d0);
        Cartesian3.add(direction, d2, direction);
        Cartesian3.normalize(direction, direction);
      } else {
        direction = p0Scratch;
        direction.x = 0;
        direction.y = 0;
        direction.z = 0;
      }
      Cartesian3.pack(
        direction,
        currentAttributes.extrudeDirection.values,
        insertedIndex * 3
      );
    }

    if (defined(applyOffset)) {
      interpolateAndPackBoolean(
        i0,
        i1,
        i2,
        coords,
        applyOffset,
        currentAttributes.applyOffset.values,
        insertedIndex
      );
    }

    if (defined(tangents)) {
      interpolateAndPackCartesian3(
        i0,
        i1,
        i2,
        coords,
        tangents,
        currentAttributes.tangent.values,
        insertedIndex,
        true
      );
    }

    if (defined(bitangents)) {
      interpolateAndPackCartesian3(
        i0,
        i1,
        i2,
        coords,
        bitangents,
        currentAttributes.bitangent.values,
        insertedIndex,
        true
      );
    }

    if (defined(texCoords)) {
      interpolateAndPackCartesian2(
        i0,
        i1,
        i2,
        coords,
        texCoords,
        currentAttributes.st.values,
        insertedIndex
      );
    }

    if (customAttributesLength > 0) {
      for (var i = 0; i < customAttributesLength; i++) {
        var attributeName = customAttributeNames[i];
        genericInterpolate(
          i0,
          i1,
          i2,
          coords,
          insertedIndex,
          allAttributes[attributeName],
          currentAttributes[attributeName]
        );
      }
    }
  }

  function genericInterpolate(
    i0,
    i1,
    i2,
    coords,
    insertedIndex,
    sourceAttribute,
    currentAttribute
  ) {
    var componentsPerAttribute = sourceAttribute.componentsPerAttribute;
    var sourceValues = sourceAttribute.values;
    var currentValues = currentAttribute.values;
    switch (componentsPerAttribute) {
      case 4:
        interpolateAndPackCartesian4(
          i0,
          i1,
          i2,
          coords,
          sourceValues,
          currentValues,
          insertedIndex,
          false
        );
        break;
      case 3:
        interpolateAndPackCartesian3(
          i0,
          i1,
          i2,
          coords,
          sourceValues,
          currentValues,
          insertedIndex,
          false
        );
        break;
      case 2:
        interpolateAndPackCartesian2(
          i0,
          i1,
          i2,
          coords,
          sourceValues,
          currentValues,
          insertedIndex,
          false
        );
        break;
      default:
        currentValues[insertedIndex] =
          sourceValues[i0] * coords.x +
          sourceValues[i1] * coords.y +
          sourceValues[i2] * coords.z;
    }
  }

  function insertSplitPoint(
    currentAttributes,
    currentIndices,
    currentIndexMap,
    indices,
    currentIndex,
    point
  ) {
    var insertIndex = currentAttributes.position.values.length / 3;

    if (currentIndex !== -1) {
      var prevIndex = indices[currentIndex];
      var newIndex = currentIndexMap[prevIndex];

      if (newIndex === -1) {
        currentIndexMap[prevIndex] = insertIndex;
        currentAttributes.position.values.push(point.x, point.y, point.z);
        currentIndices.push(insertIndex);
        return insertIndex;
      }

      currentIndices.push(newIndex);
      return newIndex;
    }

    currentAttributes.position.values.push(point.x, point.y, point.z);
    currentIndices.push(insertIndex);
    return insertIndex;
  }

  var NAMED_ATTRIBUTES = {
    position: true,
    normal: true,
    bitangent: true,
    tangent: true,
    st: true,
    extrudeDirection: true,
    applyOffset: true,
  };
  function splitLongitudeTriangles(instance) {
    var geometry = instance.geometry;
    var attributes = geometry.attributes;
    var positions = attributes.position.values;
    var normals = defined(attributes.normal)
      ? attributes.normal.values
      : undefined;
    var bitangents = defined(attributes.bitangent)
      ? attributes.bitangent.values
      : undefined;
    var tangents = defined(attributes.tangent)
      ? attributes.tangent.values
      : undefined;
    var texCoords = defined(attributes.st) ? attributes.st.values : undefined;
    var extrudeDirections = defined(attributes.extrudeDirection)
      ? attributes.extrudeDirection.values
      : undefined;
    var applyOffset = defined(attributes.applyOffset)
      ? attributes.applyOffset.values
      : undefined;
    var indices = geometry.indices;

    var customAttributeNames = [];
    for (var attributeName in attributes) {
      if (
        attributes.hasOwnProperty(attributeName) &&
        !NAMED_ATTRIBUTES[attributeName] &&
        defined(attributes[attributeName])
      ) {
        customAttributeNames.push(attributeName);
      }
    }
    var customAttributesLength = customAttributeNames.length;

    var eastGeometry = copyGeometryForSplit(geometry);
    var westGeometry = copyGeometryForSplit(geometry);

    var currentAttributes;
    var currentIndices;
    var currentIndexMap;
    var insertedIndex;
    var i;

    var westGeometryIndexMap = [];
    westGeometryIndexMap.length = positions.length / 3;

    var eastGeometryIndexMap = [];
    eastGeometryIndexMap.length = positions.length / 3;

    for (i = 0; i < westGeometryIndexMap.length; ++i) {
      westGeometryIndexMap[i] = -1;
      eastGeometryIndexMap[i] = -1;
    }

    var len = indices.length;
    for (i = 0; i < len; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];

      var p0 = Cartesian3.fromArray(positions, i0 * 3);
      var p1 = Cartesian3.fromArray(positions, i1 * 3);
      var p2 = Cartesian3.fromArray(positions, i2 * 3);

      var result = splitTriangle(p0, p1, p2);
      if (defined(result) && result.positions.length > 3) {
        var resultPositions = result.positions;
        var resultIndices = result.indices;
        var resultLength = resultIndices.length;

        for (var j = 0; j < resultLength; ++j) {
          var resultIndex = resultIndices[j];
          var point = resultPositions[resultIndex];

          if (point.y < 0.0) {
            currentAttributes = westGeometry.attributes;
            currentIndices = westGeometry.indices;
            currentIndexMap = westGeometryIndexMap;
          } else {
            currentAttributes = eastGeometry.attributes;
            currentIndices = eastGeometry.indices;
            currentIndexMap = eastGeometryIndexMap;
          }

          insertedIndex = insertSplitPoint(
            currentAttributes,
            currentIndices,
            currentIndexMap,
            indices,
            resultIndex < 3 ? i + resultIndex : -1,
            point
          );
          computeTriangleAttributes(
            i0,
            i1,
            i2,
            point,
            positions,
            normals,
            tangents,
            bitangents,
            texCoords,
            extrudeDirections,
            applyOffset,
            currentAttributes,
            customAttributeNames,
            customAttributesLength,
            attributes,
            insertedIndex
          );
        }
      } else {
        if (defined(result)) {
          p0 = result.positions[0];
          p1 = result.positions[1];
          p2 = result.positions[2];
        }

        if (p0.y < 0.0) {
          currentAttributes = westGeometry.attributes;
          currentIndices = westGeometry.indices;
          currentIndexMap = westGeometryIndexMap;
        } else {
          currentAttributes = eastGeometry.attributes;
          currentIndices = eastGeometry.indices;
          currentIndexMap = eastGeometryIndexMap;
        }

        insertedIndex = insertSplitPoint(
          currentAttributes,
          currentIndices,
          currentIndexMap,
          indices,
          i,
          p0
        );
        computeTriangleAttributes(
          i0,
          i1,
          i2,
          p0,
          positions,
          normals,
          tangents,
          bitangents,
          texCoords,
          extrudeDirections,
          applyOffset,
          currentAttributes,
          customAttributeNames,
          customAttributesLength,
          attributes,
          insertedIndex
        );

        insertedIndex = insertSplitPoint(
          currentAttributes,
          currentIndices,
          currentIndexMap,
          indices,
          i + 1,
          p1
        );
        computeTriangleAttributes(
          i0,
          i1,
          i2,
          p1,
          positions,
          normals,
          tangents,
          bitangents,
          texCoords,
          extrudeDirections,
          applyOffset,
          currentAttributes,
          customAttributeNames,
          customAttributesLength,
          attributes,
          insertedIndex
        );

        insertedIndex = insertSplitPoint(
          currentAttributes,
          currentIndices,
          currentIndexMap,
          indices,
          i + 2,
          p2
        );
        computeTriangleAttributes(
          i0,
          i1,
          i2,
          p2,
          positions,
          normals,
          tangents,
          bitangents,
          texCoords,
          extrudeDirections,
          applyOffset,
          currentAttributes,
          customAttributeNames,
          customAttributesLength,
          attributes,
          insertedIndex
        );
      }
    }

    updateInstanceAfterSplit(instance, westGeometry, eastGeometry);
  }

  var xzPlane = Plane.fromPointNormal(Cartesian3.ZERO, Cartesian3.UNIT_Y);

  var offsetScratch = new Cartesian3();
  var offsetPointScratch = new Cartesian3();

  function computeLineAttributes(
    i0,
    i1,
    point,
    positions,
    insertIndex,
    currentAttributes,
    applyOffset
  ) {
    if (!defined(applyOffset)) {
      return;
    }

    var p0 = Cartesian3.fromArray(positions, i0 * 3, p0Scratch);
    if (Cartesian3.equalsEpsilon(p0, point, CesiumMath.EPSILON10)) {
      currentAttributes.applyOffset.values[insertIndex] = applyOffset[i0];
    } else {
      currentAttributes.applyOffset.values[insertIndex] = applyOffset[i1];
    }
  }

  function splitLongitudeLines(instance) {
    var geometry = instance.geometry;
    var attributes = geometry.attributes;
    var positions = attributes.position.values;
    var applyOffset = defined(attributes.applyOffset)
      ? attributes.applyOffset.values
      : undefined;
    var indices = geometry.indices;

    var eastGeometry = copyGeometryForSplit(geometry);
    var westGeometry = copyGeometryForSplit(geometry);

    var i;
    var length = indices.length;

    var westGeometryIndexMap = [];
    westGeometryIndexMap.length = positions.length / 3;

    var eastGeometryIndexMap = [];
    eastGeometryIndexMap.length = positions.length / 3;

    for (i = 0; i < westGeometryIndexMap.length; ++i) {
      westGeometryIndexMap[i] = -1;
      eastGeometryIndexMap[i] = -1;
    }

    for (i = 0; i < length; i += 2) {
      var i0 = indices[i];
      var i1 = indices[i + 1];

      var p0 = Cartesian3.fromArray(positions, i0 * 3, p0Scratch);
      var p1 = Cartesian3.fromArray(positions, i1 * 3, p1Scratch);
      var insertIndex;

      if (Math.abs(p0.y) < CesiumMath.EPSILON6) {
        if (p0.y < 0.0) {
          p0.y = -CesiumMath.EPSILON6;
        } else {
          p0.y = CesiumMath.EPSILON6;
        }
      }

      if (Math.abs(p1.y) < CesiumMath.EPSILON6) {
        if (p1.y < 0.0) {
          p1.y = -CesiumMath.EPSILON6;
        } else {
          p1.y = CesiumMath.EPSILON6;
        }
      }

      var p0Attributes = eastGeometry.attributes;
      var p0Indices = eastGeometry.indices;
      var p0IndexMap = eastGeometryIndexMap;
      var p1Attributes = westGeometry.attributes;
      var p1Indices = westGeometry.indices;
      var p1IndexMap = westGeometryIndexMap;

      var intersection = IntersectionTests.lineSegmentPlane(
        p0,
        p1,
        xzPlane,
        p2Scratch
      );
      if (defined(intersection)) {
        // move point on the xz-plane slightly away from the plane
        var offset = Cartesian3.multiplyByScalar(
          Cartesian3.UNIT_Y,
          5.0 * CesiumMath.EPSILON9,
          offsetScratch
        );
        if (p0.y < 0.0) {
          Cartesian3.negate(offset, offset);

          p0Attributes = westGeometry.attributes;
          p0Indices = westGeometry.indices;
          p0IndexMap = westGeometryIndexMap;
          p1Attributes = eastGeometry.attributes;
          p1Indices = eastGeometry.indices;
          p1IndexMap = eastGeometryIndexMap;
        }

        var offsetPoint = Cartesian3.add(
          intersection,
          offset,
          offsetPointScratch
        );

        insertIndex = insertSplitPoint(
          p0Attributes,
          p0Indices,
          p0IndexMap,
          indices,
          i,
          p0
        );
        computeLineAttributes(
          i0,
          i1,
          p0,
          positions,
          insertIndex,
          p0Attributes,
          applyOffset
        );

        insertIndex = insertSplitPoint(
          p0Attributes,
          p0Indices,
          p0IndexMap,
          indices,
          -1,
          offsetPoint
        );
        computeLineAttributes(
          i0,
          i1,
          offsetPoint,
          positions,
          insertIndex,
          p0Attributes,
          applyOffset
        );

        Cartesian3.negate(offset, offset);
        Cartesian3.add(intersection, offset, offsetPoint);
        insertIndex = insertSplitPoint(
          p1Attributes,
          p1Indices,
          p1IndexMap,
          indices,
          -1,
          offsetPoint
        );
        computeLineAttributes(
          i0,
          i1,
          offsetPoint,
          positions,
          insertIndex,
          p1Attributes,
          applyOffset
        );

        insertIndex = insertSplitPoint(
          p1Attributes,
          p1Indices,
          p1IndexMap,
          indices,
          i + 1,
          p1
        );
        computeLineAttributes(
          i0,
          i1,
          p1,
          positions,
          insertIndex,
          p1Attributes,
          applyOffset
        );
      } else {
        var currentAttributes;
        var currentIndices;
        var currentIndexMap;

        if (p0.y < 0.0) {
          currentAttributes = westGeometry.attributes;
          currentIndices = westGeometry.indices;
          currentIndexMap = westGeometryIndexMap;
        } else {
          currentAttributes = eastGeometry.attributes;
          currentIndices = eastGeometry.indices;
          currentIndexMap = eastGeometryIndexMap;
        }

        insertIndex = insertSplitPoint(
          currentAttributes,
          currentIndices,
          currentIndexMap,
          indices,
          i,
          p0
        );
        computeLineAttributes(
          i0,
          i1,
          p0,
          positions,
          insertIndex,
          currentAttributes,
          applyOffset
        );

        insertIndex = insertSplitPoint(
          currentAttributes,
          currentIndices,
          currentIndexMap,
          indices,
          i + 1,
          p1
        );
        computeLineAttributes(
          i0,
          i1,
          p1,
          positions,
          insertIndex,
          currentAttributes,
          applyOffset
        );
      }
    }

    updateInstanceAfterSplit(instance, westGeometry, eastGeometry);
  }

  var cartesian2Scratch0 = new Cartesian2();
  var cartesian2Scratch1 = new Cartesian2();

  var cartesian3Scratch0 = new Cartesian3();
  var cartesian3Scratch2 = new Cartesian3();
  var cartesian3Scratch3 = new Cartesian3();
  var cartesian3Scratch4 = new Cartesian3();
  var cartesian3Scratch5 = new Cartesian3();
  var cartesian3Scratch6 = new Cartesian3();

  var cartesian4Scratch0 = new Cartesian4();

  function updateAdjacencyAfterSplit(geometry) {
    var attributes = geometry.attributes;
    var positions = attributes.position.values;
    var prevPositions = attributes.prevPosition.values;
    var nextPositions = attributes.nextPosition.values;

    var length = positions.length;
    for (var j = 0; j < length; j += 3) {
      var position = Cartesian3.unpack(positions, j, cartesian3Scratch0);
      if (position.x > 0.0) {
        continue;
      }

      var prevPosition = Cartesian3.unpack(prevPositions, j, cartesian3Scratch2);
      if (
        (position.y < 0.0 && prevPosition.y > 0.0) ||
        (position.y > 0.0 && prevPosition.y < 0.0)
      ) {
        if (j - 3 > 0) {
          prevPositions[j] = positions[j - 3];
          prevPositions[j + 1] = positions[j - 2];
          prevPositions[j + 2] = positions[j - 1];
        } else {
          Cartesian3.pack(position, prevPositions, j);
        }
      }

      var nextPosition = Cartesian3.unpack(nextPositions, j, cartesian3Scratch3);
      if (
        (position.y < 0.0 && nextPosition.y > 0.0) ||
        (position.y > 0.0 && nextPosition.y < 0.0)
      ) {
        if (j + 3 < length) {
          nextPositions[j] = positions[j + 3];
          nextPositions[j + 1] = positions[j + 4];
          nextPositions[j + 2] = positions[j + 5];
        } else {
          Cartesian3.pack(position, nextPositions, j);
        }
      }
    }
  }

  var offsetScalar = 5.0 * CesiumMath.EPSILON9;
  var coplanarOffset = CesiumMath.EPSILON6;

  function splitLongitudePolyline(instance) {
    var geometry = instance.geometry;
    var attributes = geometry.attributes;
    var positions = attributes.position.values;
    var prevPositions = attributes.prevPosition.values;
    var nextPositions = attributes.nextPosition.values;
    var expandAndWidths = attributes.expandAndWidth.values;

    var texCoords = defined(attributes.st) ? attributes.st.values : undefined;
    var colors = defined(attributes.color) ? attributes.color.values : undefined;

    var eastGeometry = copyGeometryForSplit(geometry);
    var westGeometry = copyGeometryForSplit(geometry);

    var i;
    var j;
    var index;

    var intersectionFound = false;

    var length = positions.length / 3;
    for (i = 0; i < length; i += 4) {
      var i0 = i;
      var i2 = i + 2;

      var p0 = Cartesian3.fromArray(positions, i0 * 3, cartesian3Scratch0);
      var p2 = Cartesian3.fromArray(positions, i2 * 3, cartesian3Scratch2);

      // Offset points that are close to the 180 longitude and change the previous/next point
      // to be the same offset point so it can be projected to 2D. There is special handling in the
      // shader for when position == prevPosition || position == nextPosition.
      if (Math.abs(p0.y) < coplanarOffset) {
        p0.y = coplanarOffset * (p2.y < 0.0 ? -1.0 : 1.0);
        positions[i * 3 + 1] = p0.y;
        positions[(i + 1) * 3 + 1] = p0.y;

        for (j = i0 * 3; j < i0 * 3 + 4 * 3; j += 3) {
          prevPositions[j] = positions[i * 3];
          prevPositions[j + 1] = positions[i * 3 + 1];
          prevPositions[j + 2] = positions[i * 3 + 2];
        }
      }

      // Do the same but for when the line crosses 180 longitude in the opposite direction.
      if (Math.abs(p2.y) < coplanarOffset) {
        p2.y = coplanarOffset * (p0.y < 0.0 ? -1.0 : 1.0);
        positions[(i + 2) * 3 + 1] = p2.y;
        positions[(i + 3) * 3 + 1] = p2.y;

        for (j = i0 * 3; j < i0 * 3 + 4 * 3; j += 3) {
          nextPositions[j] = positions[(i + 2) * 3];
          nextPositions[j + 1] = positions[(i + 2) * 3 + 1];
          nextPositions[j + 2] = positions[(i + 2) * 3 + 2];
        }
      }

      var p0Attributes = eastGeometry.attributes;
      var p0Indices = eastGeometry.indices;
      var p2Attributes = westGeometry.attributes;
      var p2Indices = westGeometry.indices;

      var intersection = IntersectionTests.lineSegmentPlane(
        p0,
        p2,
        xzPlane,
        cartesian3Scratch4
      );
      if (defined(intersection)) {
        intersectionFound = true;

        // move point on the xz-plane slightly away from the plane
        var offset = Cartesian3.multiplyByScalar(
          Cartesian3.UNIT_Y,
          offsetScalar,
          cartesian3Scratch5
        );
        if (p0.y < 0.0) {
          Cartesian3.negate(offset, offset);
          p0Attributes = westGeometry.attributes;
          p0Indices = westGeometry.indices;
          p2Attributes = eastGeometry.attributes;
          p2Indices = eastGeometry.indices;
        }

        var offsetPoint = Cartesian3.add(
          intersection,
          offset,
          cartesian3Scratch6
        );
        p0Attributes.position.values.push(p0.x, p0.y, p0.z, p0.x, p0.y, p0.z);
        p0Attributes.position.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p0Attributes.position.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );

        p0Attributes.prevPosition.values.push(
          prevPositions[i0 * 3],
          prevPositions[i0 * 3 + 1],
          prevPositions[i0 * 3 + 2]
        );
        p0Attributes.prevPosition.values.push(
          prevPositions[i0 * 3 + 3],
          prevPositions[i0 * 3 + 4],
          prevPositions[i0 * 3 + 5]
        );
        p0Attributes.prevPosition.values.push(p0.x, p0.y, p0.z, p0.x, p0.y, p0.z);

        p0Attributes.nextPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p0Attributes.nextPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p0Attributes.nextPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p0Attributes.nextPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );

        Cartesian3.negate(offset, offset);
        Cartesian3.add(intersection, offset, offsetPoint);
        p2Attributes.position.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p2Attributes.position.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p2Attributes.position.values.push(p2.x, p2.y, p2.z, p2.x, p2.y, p2.z);

        p2Attributes.prevPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p2Attributes.prevPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p2Attributes.prevPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );
        p2Attributes.prevPosition.values.push(
          offsetPoint.x,
          offsetPoint.y,
          offsetPoint.z
        );

        p2Attributes.nextPosition.values.push(p2.x, p2.y, p2.z, p2.x, p2.y, p2.z);
        p2Attributes.nextPosition.values.push(
          nextPositions[i2 * 3],
          nextPositions[i2 * 3 + 1],
          nextPositions[i2 * 3 + 2]
        );
        p2Attributes.nextPosition.values.push(
          nextPositions[i2 * 3 + 3],
          nextPositions[i2 * 3 + 4],
          nextPositions[i2 * 3 + 5]
        );

        var ew0 = Cartesian2.fromArray(
          expandAndWidths,
          i0 * 2,
          cartesian2Scratch0
        );
        var width = Math.abs(ew0.y);

        p0Attributes.expandAndWidth.values.push(-1, width, 1, width);
        p0Attributes.expandAndWidth.values.push(-1, -width, 1, -width);
        p2Attributes.expandAndWidth.values.push(-1, width, 1, width);
        p2Attributes.expandAndWidth.values.push(-1, -width, 1, -width);

        var t = Cartesian3.magnitudeSquared(
          Cartesian3.subtract(intersection, p0, cartesian3Scratch3)
        );
        t /= Cartesian3.magnitudeSquared(
          Cartesian3.subtract(p2, p0, cartesian3Scratch3)
        );

        if (defined(colors)) {
          var c0 = Cartesian4.fromArray(colors, i0 * 4, cartesian4Scratch0);
          var c2 = Cartesian4.fromArray(colors, i2 * 4, cartesian4Scratch0);

          var r = CesiumMath.lerp(c0.x, c2.x, t);
          var g = CesiumMath.lerp(c0.y, c2.y, t);
          var b = CesiumMath.lerp(c0.z, c2.z, t);
          var a = CesiumMath.lerp(c0.w, c2.w, t);

          for (j = i0 * 4; j < i0 * 4 + 2 * 4; ++j) {
            p0Attributes.color.values.push(colors[j]);
          }
          p0Attributes.color.values.push(r, g, b, a);
          p0Attributes.color.values.push(r, g, b, a);
          p2Attributes.color.values.push(r, g, b, a);
          p2Attributes.color.values.push(r, g, b, a);
          for (j = i2 * 4; j < i2 * 4 + 2 * 4; ++j) {
            p2Attributes.color.values.push(colors[j]);
          }
        }

        if (defined(texCoords)) {
          var s0 = Cartesian2.fromArray(texCoords, i0 * 2, cartesian2Scratch0);
          var s3 = Cartesian2.fromArray(
            texCoords,
            (i + 3) * 2,
            cartesian2Scratch1
          );

          var sx = CesiumMath.lerp(s0.x, s3.x, t);

          for (j = i0 * 2; j < i0 * 2 + 2 * 2; ++j) {
            p0Attributes.st.values.push(texCoords[j]);
          }
          p0Attributes.st.values.push(sx, s0.y);
          p0Attributes.st.values.push(sx, s3.y);
          p2Attributes.st.values.push(sx, s0.y);
          p2Attributes.st.values.push(sx, s3.y);
          for (j = i2 * 2; j < i2 * 2 + 2 * 2; ++j) {
            p2Attributes.st.values.push(texCoords[j]);
          }
        }

        index = p0Attributes.position.values.length / 3 - 4;
        p0Indices.push(index, index + 2, index + 1);
        p0Indices.push(index + 1, index + 2, index + 3);

        index = p2Attributes.position.values.length / 3 - 4;
        p2Indices.push(index, index + 2, index + 1);
        p2Indices.push(index + 1, index + 2, index + 3);
      } else {
        var currentAttributes;
        var currentIndices;

        if (p0.y < 0.0) {
          currentAttributes = westGeometry.attributes;
          currentIndices = westGeometry.indices;
        } else {
          currentAttributes = eastGeometry.attributes;
          currentIndices = eastGeometry.indices;
        }

        currentAttributes.position.values.push(p0.x, p0.y, p0.z);
        currentAttributes.position.values.push(p0.x, p0.y, p0.z);
        currentAttributes.position.values.push(p2.x, p2.y, p2.z);
        currentAttributes.position.values.push(p2.x, p2.y, p2.z);

        for (j = i * 3; j < i * 3 + 4 * 3; ++j) {
          currentAttributes.prevPosition.values.push(prevPositions[j]);
          currentAttributes.nextPosition.values.push(nextPositions[j]);
        }

        for (j = i * 2; j < i * 2 + 4 * 2; ++j) {
          currentAttributes.expandAndWidth.values.push(expandAndWidths[j]);
          if (defined(texCoords)) {
            currentAttributes.st.values.push(texCoords[j]);
          }
        }

        if (defined(colors)) {
          for (j = i * 4; j < i * 4 + 4 * 4; ++j) {
            currentAttributes.color.values.push(colors[j]);
          }
        }

        index = currentAttributes.position.values.length / 3 - 4;
        currentIndices.push(index, index + 2, index + 1);
        currentIndices.push(index + 1, index + 2, index + 3);
      }
    }

    if (intersectionFound) {
      updateAdjacencyAfterSplit(westGeometry);
      updateAdjacencyAfterSplit(eastGeometry);
    }

    updateInstanceAfterSplit(instance, westGeometry, eastGeometry);
  }

  /**
   * Splits the instances's geometry, by introducing new vertices and indices,that
   * intersect the International Date Line and Prime Meridian so that no primitives cross longitude
   * -180/180 degrees.  This is not required for 3D drawing, but is required for
   * correcting drawing in 2D and Columbus view.
   *
   * @private
   *
   * @param {GeometryInstance} instance The instance to modify.
   * @returns {GeometryInstance} The modified <code>instance</code> argument, with it's geometry split at the International Date Line.
   *
   * @example
   * instance = Cesium.GeometryPipeline.splitLongitude(instance);
   */
  GeometryPipeline.splitLongitude = function (instance) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(instance)) {
      throw new DeveloperError("instance is required.");
    }
    //>>includeEnd('debug');

    var geometry = instance.geometry;
    var boundingSphere = geometry.boundingSphere;
    if (defined(boundingSphere)) {
      var minX = boundingSphere.center.x - boundingSphere.radius;
      if (
        minX > 0 ||
        BoundingSphere.intersectPlane(boundingSphere, Plane.ORIGIN_ZX_PLANE) !==
          Intersect$1.INTERSECTING
      ) {
        return instance;
      }
    }

    if (geometry.geometryType !== GeometryType$1.NONE) {
      switch (geometry.geometryType) {
        case GeometryType$1.POLYLINES:
          splitLongitudePolyline(instance);
          break;
        case GeometryType$1.TRIANGLES:
          splitLongitudeTriangles(instance);
          break;
        case GeometryType$1.LINES:
          splitLongitudeLines(instance);
          break;
      }
    } else {
      indexPrimitive(geometry);
      if (geometry.primitiveType === PrimitiveType$1.TRIANGLES) {
        splitLongitudeTriangles(instance);
      } else if (geometry.primitiveType === PrimitiveType$1.LINES) {
        splitLongitudeLines(instance);
      }
    }

    return instance;
  };

  var scratchCartesian1$3 = new Cartesian3();
  var scratchCartesian2$4 = new Cartesian3();
  var scratchCartesian3$5 = new Cartesian3();
  var scratchCartesian4$1 = new Cartesian3();
  var texCoordScratch = new Cartesian2();
  var textureMatrixScratch = new Matrix3();
  var tangentMatrixScratch = new Matrix3();
  var quaternionScratch = new Quaternion();

  var scratchNormal$2 = new Cartesian3();
  var scratchTangent = new Cartesian3();
  var scratchBitangent = new Cartesian3();

  var scratchCartographic$1 = new Cartographic();
  var projectedCenterScratch = new Cartesian3();

  var scratchMinTexCoord = new Cartesian2();
  var scratchMaxTexCoord = new Cartesian2();

  function computeTopBottomAttributes(positions, options, extrude) {
    var vertexFormat = options.vertexFormat;
    var center = options.center;
    var semiMajorAxis = options.semiMajorAxis;
    var semiMinorAxis = options.semiMinorAxis;
    var ellipsoid = options.ellipsoid;
    var stRotation = options.stRotation;
    var size = extrude ? (positions.length / 3) * 2 : positions.length / 3;
    var shadowVolume = options.shadowVolume;

    var textureCoordinates = vertexFormat.st
      ? new Float32Array(size * 2)
      : undefined;
    var normals = vertexFormat.normal ? new Float32Array(size * 3) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(size * 3) : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(size * 3)
      : undefined;

    var extrudeNormals = shadowVolume ? new Float32Array(size * 3) : undefined;

    var textureCoordIndex = 0;

    // Raise positions to a height above the ellipsoid and compute the
    // texture coordinates, normals, tangents, and bitangents.
    var normal = scratchNormal$2;
    var tangent = scratchTangent;
    var bitangent = scratchBitangent;

    var projection = new GeographicProjection(ellipsoid);
    var projectedCenter = projection.project(
      ellipsoid.cartesianToCartographic(center, scratchCartographic$1),
      projectedCenterScratch
    );

    var geodeticNormal = ellipsoid.scaleToGeodeticSurface(
      center,
      scratchCartesian1$3
    );
    ellipsoid.geodeticSurfaceNormal(geodeticNormal, geodeticNormal);

    var textureMatrix = textureMatrixScratch;
    var tangentMatrix = tangentMatrixScratch;
    if (stRotation !== 0) {
      var rotation = Quaternion.fromAxisAngle(
        geodeticNormal,
        stRotation,
        quaternionScratch
      );
      textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrix);

      rotation = Quaternion.fromAxisAngle(
        geodeticNormal,
        -stRotation,
        quaternionScratch
      );
      tangentMatrix = Matrix3.fromQuaternion(rotation, tangentMatrix);
    } else {
      textureMatrix = Matrix3.clone(Matrix3.IDENTITY, textureMatrix);
      tangentMatrix = Matrix3.clone(Matrix3.IDENTITY, tangentMatrix);
    }

    var minTexCoord = Cartesian2.fromElements(
      Number.POSITIVE_INFINITY,
      Number.POSITIVE_INFINITY,
      scratchMinTexCoord
    );
    var maxTexCoord = Cartesian2.fromElements(
      Number.NEGATIVE_INFINITY,
      Number.NEGATIVE_INFINITY,
      scratchMaxTexCoord
    );

    var length = positions.length;
    var bottomOffset = extrude ? length : 0;
    var stOffset = (bottomOffset / 3) * 2;
    for (var i = 0; i < length; i += 3) {
      var i1 = i + 1;
      var i2 = i + 2;
      var position = Cartesian3.fromArray(positions, i, scratchCartesian1$3);

      if (vertexFormat.st) {
        var rotatedPoint = Matrix3.multiplyByVector(
          textureMatrix,
          position,
          scratchCartesian2$4
        );
        var projectedPoint = projection.project(
          ellipsoid.cartesianToCartographic(rotatedPoint, scratchCartographic$1),
          scratchCartesian3$5
        );
        Cartesian3.subtract(projectedPoint, projectedCenter, projectedPoint);

        texCoordScratch.x =
          (projectedPoint.x + semiMajorAxis) / (2.0 * semiMajorAxis);
        texCoordScratch.y =
          (projectedPoint.y + semiMinorAxis) / (2.0 * semiMinorAxis);

        minTexCoord.x = Math.min(texCoordScratch.x, minTexCoord.x);
        minTexCoord.y = Math.min(texCoordScratch.y, minTexCoord.y);
        maxTexCoord.x = Math.max(texCoordScratch.x, maxTexCoord.x);
        maxTexCoord.y = Math.max(texCoordScratch.y, maxTexCoord.y);

        if (extrude) {
          textureCoordinates[textureCoordIndex + stOffset] = texCoordScratch.x;
          textureCoordinates[textureCoordIndex + 1 + stOffset] =
            texCoordScratch.y;
        }

        textureCoordinates[textureCoordIndex++] = texCoordScratch.x;
        textureCoordinates[textureCoordIndex++] = texCoordScratch.y;
      }

      if (
        vertexFormat.normal ||
        vertexFormat.tangent ||
        vertexFormat.bitangent ||
        shadowVolume
      ) {
        normal = ellipsoid.geodeticSurfaceNormal(position, normal);

        if (shadowVolume) {
          extrudeNormals[i + bottomOffset] = -normal.x;
          extrudeNormals[i1 + bottomOffset] = -normal.y;
          extrudeNormals[i2 + bottomOffset] = -normal.z;
        }

        if (
          vertexFormat.normal ||
          vertexFormat.tangent ||
          vertexFormat.bitangent
        ) {
          if (vertexFormat.tangent || vertexFormat.bitangent) {
            tangent = Cartesian3.normalize(
              Cartesian3.cross(Cartesian3.UNIT_Z, normal, tangent),
              tangent
            );
            Matrix3.multiplyByVector(tangentMatrix, tangent, tangent);
          }
          if (vertexFormat.normal) {
            normals[i] = normal.x;
            normals[i1] = normal.y;
            normals[i2] = normal.z;
            if (extrude) {
              normals[i + bottomOffset] = -normal.x;
              normals[i1 + bottomOffset] = -normal.y;
              normals[i2 + bottomOffset] = -normal.z;
            }
          }

          if (vertexFormat.tangent) {
            tangents[i] = tangent.x;
            tangents[i1] = tangent.y;
            tangents[i2] = tangent.z;
            if (extrude) {
              tangents[i + bottomOffset] = -tangent.x;
              tangents[i1 + bottomOffset] = -tangent.y;
              tangents[i2 + bottomOffset] = -tangent.z;
            }
          }

          if (vertexFormat.bitangent) {
            bitangent = Cartesian3.normalize(
              Cartesian3.cross(normal, tangent, bitangent),
              bitangent
            );
            bitangents[i] = bitangent.x;
            bitangents[i1] = bitangent.y;
            bitangents[i2] = bitangent.z;
            if (extrude) {
              bitangents[i + bottomOffset] = bitangent.x;
              bitangents[i1 + bottomOffset] = bitangent.y;
              bitangents[i2 + bottomOffset] = bitangent.z;
            }
          }
        }
      }
    }

    if (vertexFormat.st) {
      length = textureCoordinates.length;
      for (var k = 0; k < length; k += 2) {
        textureCoordinates[k] =
          (textureCoordinates[k] - minTexCoord.x) /
          (maxTexCoord.x - minTexCoord.x);
        textureCoordinates[k + 1] =
          (textureCoordinates[k + 1] - minTexCoord.y) /
          (maxTexCoord.y - minTexCoord.y);
      }
    }

    var attributes = new GeometryAttributes();

    if (vertexFormat.position) {
      var finalPositions = EllipseGeometryLibrary.raisePositionsToHeight(
        positions,
        options,
        extrude
      );
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: finalPositions,
      });
    }

    if (vertexFormat.st) {
      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: textureCoordinates,
      });
    }

    if (vertexFormat.normal) {
      attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: normals,
      });
    }

    if (vertexFormat.tangent) {
      attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: tangents,
      });
    }

    if (vertexFormat.bitangent) {
      attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: bitangents,
      });
    }

    if (shadowVolume) {
      attributes.extrudeDirection = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: extrudeNormals,
      });
    }

    if (extrude && defined(options.offsetAttribute)) {
      var offsetAttribute = new Uint8Array(size);
      if (options.offsetAttribute === GeometryOffsetAttribute$1.TOP) {
        offsetAttribute = arrayFill(offsetAttribute, 1, 0, size / 2);
      } else {
        var offsetValue =
          options.offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        offsetAttribute = arrayFill(offsetAttribute, offsetValue);
      }

      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: offsetAttribute,
      });
    }

    return attributes;
  }

  function topIndices(numPts) {
    // numTriangles in half = 3 + 8 + 12 + ... = -1 + 4 + (4 + 4) + (4 + 4 + 4) + ... = -1 + 4 * (1 + 2 + 3 + ...)
    //              = -1 + 4 * ((n * ( n + 1)) / 2)
    // total triangles = 2 * numTrangles in half
    // indices = total triangles * 3;
    // Substitute numPts for n above

    var indices = new Array(12 * (numPts * (numPts + 1)) - 6);
    var indicesIndex = 0;
    var prevIndex;
    var numInterior;
    var positionIndex;
    var i;
    var j;
    // Indices triangles to the 'right' of the north vector

    prevIndex = 0;
    positionIndex = 1;
    for (i = 0; i < 3; i++) {
      indices[indicesIndex++] = positionIndex++;
      indices[indicesIndex++] = prevIndex;
      indices[indicesIndex++] = positionIndex;
    }

    for (i = 2; i < numPts + 1; ++i) {
      positionIndex = i * (i + 1) - 1;
      prevIndex = (i - 1) * i - 1;

      indices[indicesIndex++] = positionIndex++;
      indices[indicesIndex++] = prevIndex;
      indices[indicesIndex++] = positionIndex;

      numInterior = 2 * i;
      for (j = 0; j < numInterior - 1; ++j) {
        indices[indicesIndex++] = positionIndex;
        indices[indicesIndex++] = prevIndex++;
        indices[indicesIndex++] = prevIndex;

        indices[indicesIndex++] = positionIndex++;
        indices[indicesIndex++] = prevIndex;
        indices[indicesIndex++] = positionIndex;
      }

      indices[indicesIndex++] = positionIndex++;
      indices[indicesIndex++] = prevIndex;
      indices[indicesIndex++] = positionIndex;
    }

    // Indices for center column of triangles
    numInterior = numPts * 2;
    ++positionIndex;
    ++prevIndex;
    for (i = 0; i < numInterior - 1; ++i) {
      indices[indicesIndex++] = positionIndex;
      indices[indicesIndex++] = prevIndex++;
      indices[indicesIndex++] = prevIndex;

      indices[indicesIndex++] = positionIndex++;
      indices[indicesIndex++] = prevIndex;
      indices[indicesIndex++] = positionIndex;
    }

    indices[indicesIndex++] = positionIndex;
    indices[indicesIndex++] = prevIndex++;
    indices[indicesIndex++] = prevIndex;

    indices[indicesIndex++] = positionIndex++;
    indices[indicesIndex++] = prevIndex++;
    indices[indicesIndex++] = prevIndex;

    // Reverse the process creating indices to the 'left' of the north vector
    ++prevIndex;
    for (i = numPts - 1; i > 1; --i) {
      indices[indicesIndex++] = prevIndex++;
      indices[indicesIndex++] = prevIndex;
      indices[indicesIndex++] = positionIndex;

      numInterior = 2 * i;
      for (j = 0; j < numInterior - 1; ++j) {
        indices[indicesIndex++] = positionIndex;
        indices[indicesIndex++] = prevIndex++;
        indices[indicesIndex++] = prevIndex;

        indices[indicesIndex++] = positionIndex++;
        indices[indicesIndex++] = prevIndex;
        indices[indicesIndex++] = positionIndex;
      }

      indices[indicesIndex++] = prevIndex++;
      indices[indicesIndex++] = prevIndex++;
      indices[indicesIndex++] = positionIndex++;
    }

    for (i = 0; i < 3; i++) {
      indices[indicesIndex++] = prevIndex++;
      indices[indicesIndex++] = prevIndex;
      indices[indicesIndex++] = positionIndex;
    }
    return indices;
  }

  var boundingSphereCenter = new Cartesian3();

  function computeEllipse(options) {
    var center = options.center;
    boundingSphereCenter = Cartesian3.multiplyByScalar(
      options.ellipsoid.geodeticSurfaceNormal(center, boundingSphereCenter),
      options.height,
      boundingSphereCenter
    );
    boundingSphereCenter = Cartesian3.add(
      center,
      boundingSphereCenter,
      boundingSphereCenter
    );
    var boundingSphere = new BoundingSphere(
      boundingSphereCenter,
      options.semiMajorAxis
    );
    var cep = EllipseGeometryLibrary.computeEllipsePositions(
      options,
      true,
      false
    );
    var positions = cep.positions;
    var numPts = cep.numPts;
    var attributes = computeTopBottomAttributes(positions, options, false);
    var indices = topIndices(numPts);
    indices = IndexDatatype$1.createTypedArray(positions.length / 3, indices);
    return {
      boundingSphere: boundingSphere,
      attributes: attributes,
      indices: indices,
    };
  }

  function computeWallAttributes(positions, options) {
    var vertexFormat = options.vertexFormat;
    var center = options.center;
    var semiMajorAxis = options.semiMajorAxis;
    var semiMinorAxis = options.semiMinorAxis;
    var ellipsoid = options.ellipsoid;
    var height = options.height;
    var extrudedHeight = options.extrudedHeight;
    var stRotation = options.stRotation;
    var size = (positions.length / 3) * 2;

    var finalPositions = new Float64Array(size * 3);
    var textureCoordinates = vertexFormat.st
      ? new Float32Array(size * 2)
      : undefined;
    var normals = vertexFormat.normal ? new Float32Array(size * 3) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(size * 3) : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(size * 3)
      : undefined;

    var shadowVolume = options.shadowVolume;
    var extrudeNormals = shadowVolume ? new Float32Array(size * 3) : undefined;

    var textureCoordIndex = 0;

    // Raise positions to a height above the ellipsoid and compute the
    // texture coordinates, normals, tangents, and bitangents.
    var normal = scratchNormal$2;
    var tangent = scratchTangent;
    var bitangent = scratchBitangent;

    var projection = new GeographicProjection(ellipsoid);
    var projectedCenter = projection.project(
      ellipsoid.cartesianToCartographic(center, scratchCartographic$1),
      projectedCenterScratch
    );

    var geodeticNormal = ellipsoid.scaleToGeodeticSurface(
      center,
      scratchCartesian1$3
    );
    ellipsoid.geodeticSurfaceNormal(geodeticNormal, geodeticNormal);
    var rotation = Quaternion.fromAxisAngle(
      geodeticNormal,
      stRotation,
      quaternionScratch
    );
    var textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrixScratch);

    var minTexCoord = Cartesian2.fromElements(
      Number.POSITIVE_INFINITY,
      Number.POSITIVE_INFINITY,
      scratchMinTexCoord
    );
    var maxTexCoord = Cartesian2.fromElements(
      Number.NEGATIVE_INFINITY,
      Number.NEGATIVE_INFINITY,
      scratchMaxTexCoord
    );

    var length = positions.length;
    var stOffset = (length / 3) * 2;
    for (var i = 0; i < length; i += 3) {
      var i1 = i + 1;
      var i2 = i + 2;
      var position = Cartesian3.fromArray(positions, i, scratchCartesian1$3);
      var extrudedPosition;

      if (vertexFormat.st) {
        var rotatedPoint = Matrix3.multiplyByVector(
          textureMatrix,
          position,
          scratchCartesian2$4
        );
        var projectedPoint = projection.project(
          ellipsoid.cartesianToCartographic(rotatedPoint, scratchCartographic$1),
          scratchCartesian3$5
        );
        Cartesian3.subtract(projectedPoint, projectedCenter, projectedPoint);

        texCoordScratch.x =
          (projectedPoint.x + semiMajorAxis) / (2.0 * semiMajorAxis);
        texCoordScratch.y =
          (projectedPoint.y + semiMinorAxis) / (2.0 * semiMinorAxis);

        minTexCoord.x = Math.min(texCoordScratch.x, minTexCoord.x);
        minTexCoord.y = Math.min(texCoordScratch.y, minTexCoord.y);
        maxTexCoord.x = Math.max(texCoordScratch.x, maxTexCoord.x);
        maxTexCoord.y = Math.max(texCoordScratch.y, maxTexCoord.y);

        textureCoordinates[textureCoordIndex + stOffset] = texCoordScratch.x;
        textureCoordinates[textureCoordIndex + 1 + stOffset] = texCoordScratch.y;

        textureCoordinates[textureCoordIndex++] = texCoordScratch.x;
        textureCoordinates[textureCoordIndex++] = texCoordScratch.y;
      }

      position = ellipsoid.scaleToGeodeticSurface(position, position);
      extrudedPosition = Cartesian3.clone(position, scratchCartesian2$4);
      normal = ellipsoid.geodeticSurfaceNormal(position, normal);

      if (shadowVolume) {
        extrudeNormals[i + length] = -normal.x;
        extrudeNormals[i1 + length] = -normal.y;
        extrudeNormals[i2 + length] = -normal.z;
      }

      var scaledNormal = Cartesian3.multiplyByScalar(
        normal,
        height,
        scratchCartesian4$1
      );
      position = Cartesian3.add(position, scaledNormal, position);
      scaledNormal = Cartesian3.multiplyByScalar(
        normal,
        extrudedHeight,
        scaledNormal
      );
      extrudedPosition = Cartesian3.add(
        extrudedPosition,
        scaledNormal,
        extrudedPosition
      );

      if (vertexFormat.position) {
        finalPositions[i + length] = extrudedPosition.x;
        finalPositions[i1 + length] = extrudedPosition.y;
        finalPositions[i2 + length] = extrudedPosition.z;

        finalPositions[i] = position.x;
        finalPositions[i1] = position.y;
        finalPositions[i2] = position.z;
      }

      if (vertexFormat.normal || vertexFormat.tangent || vertexFormat.bitangent) {
        bitangent = Cartesian3.clone(normal, bitangent);
        var next = Cartesian3.fromArray(
          positions,
          (i + 3) % length,
          scratchCartesian4$1
        );
        Cartesian3.subtract(next, position, next);
        var bottom = Cartesian3.subtract(
          extrudedPosition,
          position,
          scratchCartesian3$5
        );

        normal = Cartesian3.normalize(
          Cartesian3.cross(bottom, next, normal),
          normal
        );

        if (vertexFormat.normal) {
          normals[i] = normal.x;
          normals[i1] = normal.y;
          normals[i2] = normal.z;

          normals[i + length] = normal.x;
          normals[i1 + length] = normal.y;
          normals[i2 + length] = normal.z;
        }

        if (vertexFormat.tangent) {
          tangent = Cartesian3.normalize(
            Cartesian3.cross(bitangent, normal, tangent),
            tangent
          );
          tangents[i] = tangent.x;
          tangents[i1] = tangent.y;
          tangents[i2] = tangent.z;

          tangents[i + length] = tangent.x;
          tangents[i + 1 + length] = tangent.y;
          tangents[i + 2 + length] = tangent.z;
        }

        if (vertexFormat.bitangent) {
          bitangents[i] = bitangent.x;
          bitangents[i1] = bitangent.y;
          bitangents[i2] = bitangent.z;

          bitangents[i + length] = bitangent.x;
          bitangents[i1 + length] = bitangent.y;
          bitangents[i2 + length] = bitangent.z;
        }
      }
    }

    if (vertexFormat.st) {
      length = textureCoordinates.length;
      for (var k = 0; k < length; k += 2) {
        textureCoordinates[k] =
          (textureCoordinates[k] - minTexCoord.x) /
          (maxTexCoord.x - minTexCoord.x);
        textureCoordinates[k + 1] =
          (textureCoordinates[k + 1] - minTexCoord.y) /
          (maxTexCoord.y - minTexCoord.y);
      }
    }

    var attributes = new GeometryAttributes();

    if (vertexFormat.position) {
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: finalPositions,
      });
    }

    if (vertexFormat.st) {
      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: textureCoordinates,
      });
    }

    if (vertexFormat.normal) {
      attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: normals,
      });
    }

    if (vertexFormat.tangent) {
      attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: tangents,
      });
    }

    if (vertexFormat.bitangent) {
      attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: bitangents,
      });
    }

    if (shadowVolume) {
      attributes.extrudeDirection = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: extrudeNormals,
      });
    }

    if (defined(options.offsetAttribute)) {
      var offsetAttribute = new Uint8Array(size);
      if (options.offsetAttribute === GeometryOffsetAttribute$1.TOP) {
        offsetAttribute = arrayFill(offsetAttribute, 1, 0, size / 2);
      } else {
        var offsetValue =
          options.offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        offsetAttribute = arrayFill(offsetAttribute, offsetValue);
      }
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: offsetAttribute,
      });
    }

    return attributes;
  }

  function computeWallIndices(positions) {
    var length = positions.length / 3;
    var indices = IndexDatatype$1.createTypedArray(length, length * 6);
    var index = 0;
    for (var i = 0; i < length; i++) {
      var UL = i;
      var LL = i + length;
      var UR = (UL + 1) % length;
      var LR = UR + length;
      indices[index++] = UL;
      indices[index++] = LL;
      indices[index++] = UR;
      indices[index++] = UR;
      indices[index++] = LL;
      indices[index++] = LR;
    }

    return indices;
  }

  var topBoundingSphere = new BoundingSphere();
  var bottomBoundingSphere = new BoundingSphere();

  function computeExtrudedEllipse(options) {
    var center = options.center;
    var ellipsoid = options.ellipsoid;
    var semiMajorAxis = options.semiMajorAxis;
    var scaledNormal = Cartesian3.multiplyByScalar(
      ellipsoid.geodeticSurfaceNormal(center, scratchCartesian1$3),
      options.height,
      scratchCartesian1$3
    );
    topBoundingSphere.center = Cartesian3.add(
      center,
      scaledNormal,
      topBoundingSphere.center
    );
    topBoundingSphere.radius = semiMajorAxis;

    scaledNormal = Cartesian3.multiplyByScalar(
      ellipsoid.geodeticSurfaceNormal(center, scaledNormal),
      options.extrudedHeight,
      scaledNormal
    );
    bottomBoundingSphere.center = Cartesian3.add(
      center,
      scaledNormal,
      bottomBoundingSphere.center
    );
    bottomBoundingSphere.radius = semiMajorAxis;

    var cep = EllipseGeometryLibrary.computeEllipsePositions(options, true, true);
    var positions = cep.positions;
    var numPts = cep.numPts;
    var outerPositions = cep.outerPositions;
    var boundingSphere = BoundingSphere.union(
      topBoundingSphere,
      bottomBoundingSphere
    );
    var topBottomAttributes = computeTopBottomAttributes(
      positions,
      options,
      true
    );
    var indices = topIndices(numPts);
    var length = indices.length;
    indices.length = length * 2;
    var posLength = positions.length / 3;
    for (var i = 0; i < length; i += 3) {
      indices[i + length] = indices[i + 2] + posLength;
      indices[i + 1 + length] = indices[i + 1] + posLength;
      indices[i + 2 + length] = indices[i] + posLength;
    }

    var topBottomIndices = IndexDatatype$1.createTypedArray(
      (posLength * 2) / 3,
      indices
    );

    var topBottomGeo = new Geometry({
      attributes: topBottomAttributes,
      indices: topBottomIndices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    });

    var wallAttributes = computeWallAttributes(outerPositions, options);
    indices = computeWallIndices(outerPositions);
    var wallIndices = IndexDatatype$1.createTypedArray(
      (outerPositions.length * 2) / 3,
      indices
    );

    var wallGeo = new Geometry({
      attributes: wallAttributes,
      indices: wallIndices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    });

    var geo = GeometryPipeline.combineInstances([
      new GeometryInstance({
        geometry: topBottomGeo,
      }),
      new GeometryInstance({
        geometry: wallGeo,
      }),
    ]);

    return {
      boundingSphere: boundingSphere,
      attributes: geo[0].attributes,
      indices: geo[0].indices,
    };
  }

  function computeRectangle(
    center,
    semiMajorAxis,
    semiMinorAxis,
    rotation,
    granularity,
    ellipsoid,
    result
  ) {
    var cep = EllipseGeometryLibrary.computeEllipsePositions(
      {
        center: center,
        semiMajorAxis: semiMajorAxis,
        semiMinorAxis: semiMinorAxis,
        rotation: rotation,
        granularity: granularity,
      },
      false,
      true
    );
    var positionsFlat = cep.outerPositions;
    var positionsCount = positionsFlat.length / 3;
    var positions = new Array(positionsCount);
    for (var i = 0; i < positionsCount; ++i) {
      positions[i] = Cartesian3.fromArray(positionsFlat, i * 3);
    }
    var rectangle = Rectangle.fromCartesianArray(positions, ellipsoid, result);
    // Rectangle width goes beyond 180 degrees when the ellipse crosses a pole.
    // When this happens, make the rectangle into a "circle" around the pole
    if (rectangle.width > CesiumMath.PI) {
      rectangle.north =
        rectangle.north > 0.0
          ? CesiumMath.PI_OVER_TWO - CesiumMath.EPSILON7
          : rectangle.north;
      rectangle.south =
        rectangle.south < 0.0
          ? CesiumMath.EPSILON7 - CesiumMath.PI_OVER_TWO
          : rectangle.south;
      rectangle.east = CesiumMath.PI;
      rectangle.west = -CesiumMath.PI;
    }
    return rectangle;
  }

  /**
   * A description of an ellipse on an ellipsoid. Ellipse geometry can be rendered with both {@link Primitive} and {@link GroundPrimitive}.
   *
   * @alias EllipseGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.center The ellipse's center point in the fixed frame.
   * @param {Number} options.semiMajorAxis The length of the ellipse's semi-major axis in meters.
   * @param {Number} options.semiMinorAxis The length of the ellipse's semi-minor axis in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid the ellipse will be on.
   * @param {Number} [options.height=0.0] The distance in meters between the ellipse and the ellipsoid surface.
   * @param {Number} [options.extrudedHeight] The distance in meters between the ellipse's extruded face and the ellipsoid surface.
   * @param {Number} [options.rotation=0.0] The angle of rotation counter-clockwise from north.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates counter-clockwise from north.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The angular distance between points on the ellipse in radians.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @exception {DeveloperError} semiMajorAxis and semiMinorAxis must be greater than zero.
   * @exception {DeveloperError} semiMajorAxis must be greater than or equal to the semiMinorAxis.
   * @exception {DeveloperError} granularity must be greater than zero.
   *
   *
   * @example
   * // Create an ellipse.
   * var ellipse = new Cesium.EllipseGeometry({
   *   center : Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883),
   *   semiMajorAxis : 500000.0,
   *   semiMinorAxis : 300000.0,
   *   rotation : Cesium.Math.toRadians(60.0)
   * });
   * var geometry = Cesium.EllipseGeometry.createGeometry(ellipse);
   *
   * @see EllipseGeometry.createGeometry
   */
  function EllipseGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var center = options.center;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var semiMajorAxis = options.semiMajorAxis;
    var semiMinorAxis = options.semiMinorAxis;
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.center", center);
    Check.typeOf.number("options.semiMajorAxis", semiMajorAxis);
    Check.typeOf.number("options.semiMinorAxis", semiMinorAxis);
    if (semiMajorAxis < semiMinorAxis) {
      throw new DeveloperError(
        "semiMajorAxis must be greater than or equal to the semiMinorAxis."
      );
    }
    if (granularity <= 0.0) {
      throw new DeveloperError("granularity must be greater than zero.");
    }
    //>>includeEnd('debug');

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    this._center = Cartesian3.clone(center);
    this._semiMajorAxis = semiMajorAxis;
    this._semiMinorAxis = semiMinorAxis;
    this._ellipsoid = Ellipsoid.clone(ellipsoid);
    this._rotation = defaultValue(options.rotation, 0.0);
    this._stRotation = defaultValue(options.stRotation, 0.0);
    this._height = Math.max(extrudedHeight, height);
    this._granularity = granularity;
    this._vertexFormat = VertexFormat.clone(vertexFormat);
    this._extrudedHeight = Math.min(extrudedHeight, height);
    this._shadowVolume = defaultValue(options.shadowVolume, false);
    this._workerName = "createEllipseGeometry";
    this._offsetAttribute = options.offsetAttribute;

    this._rectangle = undefined;
    this._textureCoordinateRotationPoints = undefined;
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  EllipseGeometry.packedLength =
    Cartesian3.packedLength +
    Ellipsoid.packedLength +
    VertexFormat.packedLength +
    9;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {EllipseGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  EllipseGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._center, array, startingIndex);
    startingIndex += Cartesian3.packedLength;

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._semiMajorAxis;
    array[startingIndex++] = value._semiMinorAxis;
    array[startingIndex++] = value._rotation;
    array[startingIndex++] = value._stRotation;
    array[startingIndex++] = value._height;
    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._shadowVolume ? 1.0 : 0.0;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchCenter$1 = new Cartesian3();
  var scratchEllipsoid = new Ellipsoid();
  var scratchVertexFormat$1 = new VertexFormat();
  var scratchOptions$2 = {
    center: scratchCenter$1,
    ellipsoid: scratchEllipsoid,
    vertexFormat: scratchVertexFormat$1,
    semiMajorAxis: undefined,
    semiMinorAxis: undefined,
    rotation: undefined,
    stRotation: undefined,
    height: undefined,
    granularity: undefined,
    extrudedHeight: undefined,
    shadowVolume: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {EllipseGeometry} [result] The object into which to store the result.
   * @returns {EllipseGeometry} The modified result parameter or a new EllipseGeometry instance if one was not provided.
   */
  EllipseGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var center = Cartesian3.unpack(array, startingIndex, scratchCenter$1);
    startingIndex += Cartesian3.packedLength;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$1
    );
    startingIndex += VertexFormat.packedLength;

    var semiMajorAxis = array[startingIndex++];
    var semiMinorAxis = array[startingIndex++];
    var rotation = array[startingIndex++];
    var stRotation = array[startingIndex++];
    var height = array[startingIndex++];
    var granularity = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var shadowVolume = array[startingIndex++] === 1.0;
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$2.height = height;
      scratchOptions$2.extrudedHeight = extrudedHeight;
      scratchOptions$2.granularity = granularity;
      scratchOptions$2.stRotation = stRotation;
      scratchOptions$2.rotation = rotation;
      scratchOptions$2.semiMajorAxis = semiMajorAxis;
      scratchOptions$2.semiMinorAxis = semiMinorAxis;
      scratchOptions$2.shadowVolume = shadowVolume;
      scratchOptions$2.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;

      return new EllipseGeometry(scratchOptions$2);
    }

    result._center = Cartesian3.clone(center, result._center);
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._semiMajorAxis = semiMajorAxis;
    result._semiMinorAxis = semiMinorAxis;
    result._rotation = rotation;
    result._stRotation = stRotation;
    result._height = height;
    result._granularity = granularity;
    result._extrudedHeight = extrudedHeight;
    result._shadowVolume = shadowVolume;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the bounding rectangle based on the provided options
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.center The ellipse's center point in the fixed frame.
   * @param {Number} options.semiMajorAxis The length of the ellipse's semi-major axis in meters.
   * @param {Number} options.semiMinorAxis The length of the ellipse's semi-minor axis in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid the ellipse will be on.
   * @param {Number} [options.rotation=0.0] The angle of rotation counter-clockwise from north.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The angular distance between points on the ellipse in radians.
   * @param {Rectangle} [result] An object in which to store the result
   *
   * @returns {Rectangle} The result rectangle
   */
  EllipseGeometry.computeRectangle = function (options, result) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var center = options.center;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var semiMajorAxis = options.semiMajorAxis;
    var semiMinorAxis = options.semiMinorAxis;
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var rotation = defaultValue(options.rotation, 0.0);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.center", center);
    Check.typeOf.number("options.semiMajorAxis", semiMajorAxis);
    Check.typeOf.number("options.semiMinorAxis", semiMinorAxis);
    if (semiMajorAxis < semiMinorAxis) {
      throw new DeveloperError(
        "semiMajorAxis must be greater than or equal to the semiMinorAxis."
      );
    }
    if (granularity <= 0.0) {
      throw new DeveloperError("granularity must be greater than zero.");
    }
    //>>includeEnd('debug');

    return computeRectangle(
      center,
      semiMajorAxis,
      semiMinorAxis,
      rotation,
      granularity,
      ellipsoid,
      result
    );
  };

  /**
   * Computes the geometric representation of a ellipse on an ellipsoid, including its vertices, indices, and a bounding sphere.
   *
   * @param {EllipseGeometry} ellipseGeometry A description of the ellipse.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  EllipseGeometry.createGeometry = function (ellipseGeometry) {
    if (
      ellipseGeometry._semiMajorAxis <= 0.0 ||
      ellipseGeometry._semiMinorAxis <= 0.0
    ) {
      return;
    }

    var height = ellipseGeometry._height;
    var extrudedHeight = ellipseGeometry._extrudedHeight;
    var extrude = !CesiumMath.equalsEpsilon(
      height,
      extrudedHeight,
      0,
      CesiumMath.EPSILON2
    );

    ellipseGeometry._center = ellipseGeometry._ellipsoid.scaleToGeodeticSurface(
      ellipseGeometry._center,
      ellipseGeometry._center
    );
    var options = {
      center: ellipseGeometry._center,
      semiMajorAxis: ellipseGeometry._semiMajorAxis,
      semiMinorAxis: ellipseGeometry._semiMinorAxis,
      ellipsoid: ellipseGeometry._ellipsoid,
      rotation: ellipseGeometry._rotation,
      height: height,
      granularity: ellipseGeometry._granularity,
      vertexFormat: ellipseGeometry._vertexFormat,
      stRotation: ellipseGeometry._stRotation,
    };
    var geometry;
    if (extrude) {
      options.extrudedHeight = extrudedHeight;
      options.shadowVolume = ellipseGeometry._shadowVolume;
      options.offsetAttribute = ellipseGeometry._offsetAttribute;
      geometry = computeExtrudedEllipse(options);
    } else {
      geometry = computeEllipse(options);

      if (defined(ellipseGeometry._offsetAttribute)) {
        var length = geometry.attributes.position.values.length;
        var applyOffset = new Uint8Array(length / 3);
        var offsetValue =
          ellipseGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
            ? 0
            : 1;
        arrayFill(applyOffset, offsetValue);
        geometry.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: applyOffset,
        });
      }
    }

    return new Geometry({
      attributes: geometry.attributes,
      indices: geometry.indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: geometry.boundingSphere,
      offsetAttribute: ellipseGeometry._offsetAttribute,
    });
  };

  /**
   * @private
   */
  EllipseGeometry.createShadowVolume = function (
    ellipseGeometry,
    minHeightFunc,
    maxHeightFunc
  ) {
    var granularity = ellipseGeometry._granularity;
    var ellipsoid = ellipseGeometry._ellipsoid;

    var minHeight = minHeightFunc(granularity, ellipsoid);
    var maxHeight = maxHeightFunc(granularity, ellipsoid);

    return new EllipseGeometry({
      center: ellipseGeometry._center,
      semiMajorAxis: ellipseGeometry._semiMajorAxis,
      semiMinorAxis: ellipseGeometry._semiMinorAxis,
      ellipsoid: ellipsoid,
      rotation: ellipseGeometry._rotation,
      stRotation: ellipseGeometry._stRotation,
      granularity: granularity,
      extrudedHeight: minHeight,
      height: maxHeight,
      vertexFormat: VertexFormat.POSITION_ONLY,
      shadowVolume: true,
    });
  };

  function textureCoordinateRotationPoints(ellipseGeometry) {
    var stRotation = -ellipseGeometry._stRotation;
    if (stRotation === 0.0) {
      return [0, 0, 0, 1, 1, 0];
    }

    var cep = EllipseGeometryLibrary.computeEllipsePositions(
      {
        center: ellipseGeometry._center,
        semiMajorAxis: ellipseGeometry._semiMajorAxis,
        semiMinorAxis: ellipseGeometry._semiMinorAxis,
        rotation: ellipseGeometry._rotation,
        granularity: ellipseGeometry._granularity,
      },
      false,
      true
    );
    var positionsFlat = cep.outerPositions;
    var positionsCount = positionsFlat.length / 3;
    var positions = new Array(positionsCount);
    for (var i = 0; i < positionsCount; ++i) {
      positions[i] = Cartesian3.fromArray(positionsFlat, i * 3);
    }

    var ellipsoid = ellipseGeometry._ellipsoid;
    var boundingRectangle = ellipseGeometry.rectangle;
    return Geometry._textureCoordinateRotationPoints(
      positions,
      stRotation,
      ellipsoid,
      boundingRectangle
    );
  }

  Object.defineProperties(EllipseGeometry.prototype, {
    /**
     * @private
     */
    rectangle: {
      get: function () {
        if (!defined(this._rectangle)) {
          this._rectangle = computeRectangle(
            this._center,
            this._semiMajorAxis,
            this._semiMinorAxis,
            this._rotation,
            this._granularity,
            this._ellipsoid
          );
        }
        return this._rectangle;
      },
    },
    /**
     * For remapping texture coordinates when rendering EllipseGeometries as GroundPrimitives.
     * @private
     */
    textureCoordinateRotationPoints: {
      get: function () {
        if (!defined(this._textureCoordinateRotationPoints)) {
          this._textureCoordinateRotationPoints = textureCoordinateRotationPoints(
            this
          );
        }
        return this._textureCoordinateRotationPoints;
      },
    },
  });

  /**
   * A description of a circle on the ellipsoid. Circle geometry can be rendered with both {@link Primitive} and {@link GroundPrimitive}.
   *
   * @alias CircleGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.center The circle's center point in the fixed frame.
   * @param {Number} options.radius The radius in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid the circle will be on.
   * @param {Number} [options.height=0.0] The distance in meters between the circle and the ellipsoid surface.
   * @param {Number} [options.granularity=0.02] The angular distance between points on the circle in radians.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Number} [options.extrudedHeight=0.0] The distance in meters between the circle's extruded face and the ellipsoid surface.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates, in radians. A positive rotation is counter-clockwise.
   *
   * @exception {DeveloperError} radius must be greater than zero.
   * @exception {DeveloperError} granularity must be greater than zero.
   *
   * @see CircleGeometry.createGeometry
   * @see Packable
   *
   * @example
   * // Create a circle.
   * var circle = new Cesium.CircleGeometry({
   *   center : Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883),
   *   radius : 100000.0
   * });
   * var geometry = Cesium.CircleGeometry.createGeometry(circle);
   */
  function CircleGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var radius = options.radius;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("radius", radius);
    //>>includeEnd('debug');

    var ellipseGeometryOptions = {
      center: options.center,
      semiMajorAxis: radius,
      semiMinorAxis: radius,
      ellipsoid: options.ellipsoid,
      height: options.height,
      extrudedHeight: options.extrudedHeight,
      granularity: options.granularity,
      vertexFormat: options.vertexFormat,
      stRotation: options.stRotation,
      shadowVolume: options.shadowVolume,
    };
    this._ellipseGeometry = new EllipseGeometry(ellipseGeometryOptions);
    this._workerName = "createCircleGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  CircleGeometry.packedLength = EllipseGeometry.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CircleGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CircleGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    //>>includeEnd('debug');
    return EllipseGeometry.pack(value._ellipseGeometry, array, startingIndex);
  };

  var scratchEllipseGeometry = new EllipseGeometry({
    center: new Cartesian3(),
    semiMajorAxis: 1.0,
    semiMinorAxis: 1.0,
  });
  var scratchOptions$3 = {
    center: new Cartesian3(),
    radius: undefined,
    ellipsoid: Ellipsoid.clone(Ellipsoid.UNIT_SPHERE),
    height: undefined,
    extrudedHeight: undefined,
    granularity: undefined,
    vertexFormat: new VertexFormat(),
    stRotation: undefined,
    semiMajorAxis: undefined,
    semiMinorAxis: undefined,
    shadowVolume: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CircleGeometry} [result] The object into which to store the result.
   * @returns {CircleGeometry} The modified result parameter or a new CircleGeometry instance if one was not provided.
   */
  CircleGeometry.unpack = function (array, startingIndex, result) {
    var ellipseGeometry = EllipseGeometry.unpack(
      array,
      startingIndex,
      scratchEllipseGeometry
    );
    scratchOptions$3.center = Cartesian3.clone(
      ellipseGeometry._center,
      scratchOptions$3.center
    );
    scratchOptions$3.ellipsoid = Ellipsoid.clone(
      ellipseGeometry._ellipsoid,
      scratchOptions$3.ellipsoid
    );
    scratchOptions$3.height = ellipseGeometry._height;
    scratchOptions$3.extrudedHeight = ellipseGeometry._extrudedHeight;
    scratchOptions$3.granularity = ellipseGeometry._granularity;
    scratchOptions$3.vertexFormat = VertexFormat.clone(
      ellipseGeometry._vertexFormat,
      scratchOptions$3.vertexFormat
    );
    scratchOptions$3.stRotation = ellipseGeometry._stRotation;
    scratchOptions$3.shadowVolume = ellipseGeometry._shadowVolume;

    if (!defined(result)) {
      scratchOptions$3.radius = ellipseGeometry._semiMajorAxis;
      return new CircleGeometry(scratchOptions$3);
    }

    scratchOptions$3.semiMajorAxis = ellipseGeometry._semiMajorAxis;
    scratchOptions$3.semiMinorAxis = ellipseGeometry._semiMinorAxis;
    result._ellipseGeometry = new EllipseGeometry(scratchOptions$3);
    return result;
  };

  /**
   * Computes the geometric representation of a circle on an ellipsoid, including its vertices, indices, and a bounding sphere.
   *
   * @param {CircleGeometry} circleGeometry A description of the circle.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CircleGeometry.createGeometry = function (circleGeometry) {
    return EllipseGeometry.createGeometry(circleGeometry._ellipseGeometry);
  };

  /**
   * @private
   */
  CircleGeometry.createShadowVolume = function (
    circleGeometry,
    minHeightFunc,
    maxHeightFunc
  ) {
    var granularity = circleGeometry._ellipseGeometry._granularity;
    var ellipsoid = circleGeometry._ellipseGeometry._ellipsoid;

    var minHeight = minHeightFunc(granularity, ellipsoid);
    var maxHeight = maxHeightFunc(granularity, ellipsoid);

    return new CircleGeometry({
      center: circleGeometry._ellipseGeometry._center,
      radius: circleGeometry._ellipseGeometry._semiMajorAxis,
      ellipsoid: ellipsoid,
      stRotation: circleGeometry._ellipseGeometry._stRotation,
      granularity: granularity,
      extrudedHeight: minHeight,
      height: maxHeight,
      vertexFormat: VertexFormat.POSITION_ONLY,
      shadowVolume: true,
    });
  };

  Object.defineProperties(CircleGeometry.prototype, {
    /**
     * @private
     */
    rectangle: {
      get: function () {
        return this._ellipseGeometry.rectangle;
      },
    },
    /**
     * For remapping texture coordinates when rendering CircleGeometries as GroundPrimitives.
     * @private
     */
    textureCoordinateRotationPoints: {
      get: function () {
        return this._ellipseGeometry.textureCoordinateRotationPoints;
      },
    },
  });

  var scratchCartesian1$4 = new Cartesian3();
  var boundingSphereCenter$1 = new Cartesian3();

  function computeEllipse$1(options) {
    var center = options.center;
    boundingSphereCenter$1 = Cartesian3.multiplyByScalar(
      options.ellipsoid.geodeticSurfaceNormal(center, boundingSphereCenter$1),
      options.height,
      boundingSphereCenter$1
    );
    boundingSphereCenter$1 = Cartesian3.add(
      center,
      boundingSphereCenter$1,
      boundingSphereCenter$1
    );
    var boundingSphere = new BoundingSphere(
      boundingSphereCenter$1,
      options.semiMajorAxis
    );
    var positions = EllipseGeometryLibrary.computeEllipsePositions(
      options,
      false,
      true
    ).outerPositions;

    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: EllipseGeometryLibrary.raisePositionsToHeight(
          positions,
          options,
          false
        ),
      }),
    });

    var length = positions.length / 3;
    var indices = IndexDatatype$1.createTypedArray(length, length * 2);
    var index = 0;
    for (var i = 0; i < length; ++i) {
      indices[index++] = i;
      indices[index++] = (i + 1) % length;
    }

    return {
      boundingSphere: boundingSphere,
      attributes: attributes,
      indices: indices,
    };
  }

  var topBoundingSphere$1 = new BoundingSphere();
  var bottomBoundingSphere$1 = new BoundingSphere();
  function computeExtrudedEllipse$1(options) {
    var center = options.center;
    var ellipsoid = options.ellipsoid;
    var semiMajorAxis = options.semiMajorAxis;
    var scaledNormal = Cartesian3.multiplyByScalar(
      ellipsoid.geodeticSurfaceNormal(center, scratchCartesian1$4),
      options.height,
      scratchCartesian1$4
    );
    topBoundingSphere$1.center = Cartesian3.add(
      center,
      scaledNormal,
      topBoundingSphere$1.center
    );
    topBoundingSphere$1.radius = semiMajorAxis;

    scaledNormal = Cartesian3.multiplyByScalar(
      ellipsoid.geodeticSurfaceNormal(center, scaledNormal),
      options.extrudedHeight,
      scaledNormal
    );
    bottomBoundingSphere$1.center = Cartesian3.add(
      center,
      scaledNormal,
      bottomBoundingSphere$1.center
    );
    bottomBoundingSphere$1.radius = semiMajorAxis;

    var positions = EllipseGeometryLibrary.computeEllipsePositions(
      options,
      false,
      true
    ).outerPositions;
    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: EllipseGeometryLibrary.raisePositionsToHeight(
          positions,
          options,
          true
        ),
      }),
    });

    positions = attributes.position.values;
    var boundingSphere = BoundingSphere.union(
      topBoundingSphere$1,
      bottomBoundingSphere$1
    );
    var length = positions.length / 3;

    if (defined(options.offsetAttribute)) {
      var applyOffset = new Uint8Array(length);
      if (options.offsetAttribute === GeometryOffsetAttribute$1.TOP) {
        applyOffset = arrayFill(applyOffset, 1, 0, length / 2);
      } else {
        var offsetValue =
          options.offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        applyOffset = arrayFill(applyOffset, offsetValue);
      }

      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    var numberOfVerticalLines = defaultValue(options.numberOfVerticalLines, 16);
    numberOfVerticalLines = CesiumMath.clamp(
      numberOfVerticalLines,
      0,
      length / 2
    );

    var indices = IndexDatatype$1.createTypedArray(
      length,
      length * 2 + numberOfVerticalLines * 2
    );

    length /= 2;
    var index = 0;
    var i;
    for (i = 0; i < length; ++i) {
      indices[index++] = i;
      indices[index++] = (i + 1) % length;
      indices[index++] = i + length;
      indices[index++] = ((i + 1) % length) + length;
    }

    var numSide;
    if (numberOfVerticalLines > 0) {
      var numSideLines = Math.min(numberOfVerticalLines, length);
      numSide = Math.round(length / numSideLines);

      var maxI = Math.min(numSide * numberOfVerticalLines, length);
      for (i = 0; i < maxI; i += numSide) {
        indices[index++] = i;
        indices[index++] = i + length;
      }
    }

    return {
      boundingSphere: boundingSphere,
      attributes: attributes,
      indices: indices,
    };
  }

  /**
   * A description of the outline of an ellipse on an ellipsoid.
   *
   * @alias EllipseOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.center The ellipse's center point in the fixed frame.
   * @param {Number} options.semiMajorAxis The length of the ellipse's semi-major axis in meters.
   * @param {Number} options.semiMinorAxis The length of the ellipse's semi-minor axis in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid the ellipse will be on.
   * @param {Number} [options.height=0.0] The distance in meters between the ellipse and the ellipsoid surface.
   * @param {Number} [options.extrudedHeight] The distance in meters between the ellipse's extruded face and the ellipsoid surface.
   * @param {Number} [options.rotation=0.0] The angle from north (counter-clockwise) in radians.
   * @param {Number} [options.granularity=0.02] The angular distance between points on the ellipse in radians.
   * @param {Number} [options.numberOfVerticalLines=16] Number of lines to draw between the top and bottom surface of an extruded ellipse.
   *
   * @exception {DeveloperError} semiMajorAxis and semiMinorAxis must be greater than zero.
   * @exception {DeveloperError} semiMajorAxis must be greater than or equal to the semiMinorAxis.
   * @exception {DeveloperError} granularity must be greater than zero.
   *
   * @see EllipseOutlineGeometry.createGeometry
   *
   * @example
   * var ellipse = new Cesium.EllipseOutlineGeometry({
   *   center : Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883),
   *   semiMajorAxis : 500000.0,
   *   semiMinorAxis : 300000.0,
   *   rotation : Cesium.Math.toRadians(60.0)
   * });
   * var geometry = Cesium.EllipseOutlineGeometry.createGeometry(ellipse);
   */
  function EllipseOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var center = options.center;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var semiMajorAxis = options.semiMajorAxis;
    var semiMinorAxis = options.semiMinorAxis;
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );

    //>>includeStart('debug', pragmas.debug);
    if (!defined(center)) {
      throw new DeveloperError("center is required.");
    }
    if (!defined(semiMajorAxis)) {
      throw new DeveloperError("semiMajorAxis is required.");
    }
    if (!defined(semiMinorAxis)) {
      throw new DeveloperError("semiMinorAxis is required.");
    }
    if (semiMajorAxis < semiMinorAxis) {
      throw new DeveloperError(
        "semiMajorAxis must be greater than or equal to the semiMinorAxis."
      );
    }
    if (granularity <= 0.0) {
      throw new DeveloperError("granularity must be greater than zero.");
    }
    //>>includeEnd('debug');

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    this._center = Cartesian3.clone(center);
    this._semiMajorAxis = semiMajorAxis;
    this._semiMinorAxis = semiMinorAxis;
    this._ellipsoid = Ellipsoid.clone(ellipsoid);
    this._rotation = defaultValue(options.rotation, 0.0);
    this._height = Math.max(extrudedHeight, height);
    this._granularity = granularity;
    this._extrudedHeight = Math.min(extrudedHeight, height);
    this._numberOfVerticalLines = Math.max(
      defaultValue(options.numberOfVerticalLines, 16),
      0
    );
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createEllipseOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  EllipseOutlineGeometry.packedLength =
    Cartesian3.packedLength + Ellipsoid.packedLength + 8;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {EllipseOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  EllipseOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._center, array, startingIndex);
    startingIndex += Cartesian3.packedLength;

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex++] = value._semiMajorAxis;
    array[startingIndex++] = value._semiMinorAxis;
    array[startingIndex++] = value._rotation;
    array[startingIndex++] = value._height;
    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._numberOfVerticalLines;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchCenter$2 = new Cartesian3();
  var scratchEllipsoid$1 = new Ellipsoid();
  var scratchOptions$4 = {
    center: scratchCenter$2,
    ellipsoid: scratchEllipsoid$1,
    semiMajorAxis: undefined,
    semiMinorAxis: undefined,
    rotation: undefined,
    height: undefined,
    granularity: undefined,
    extrudedHeight: undefined,
    numberOfVerticalLines: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {EllipseOutlineGeometry} [result] The object into which to store the result.
   * @returns {EllipseOutlineGeometry} The modified result parameter or a new EllipseOutlineGeometry instance if one was not provided.
   */
  EllipseOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var center = Cartesian3.unpack(array, startingIndex, scratchCenter$2);
    startingIndex += Cartesian3.packedLength;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$1);
    startingIndex += Ellipsoid.packedLength;

    var semiMajorAxis = array[startingIndex++];
    var semiMinorAxis = array[startingIndex++];
    var rotation = array[startingIndex++];
    var height = array[startingIndex++];
    var granularity = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var numberOfVerticalLines = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$4.height = height;
      scratchOptions$4.extrudedHeight = extrudedHeight;
      scratchOptions$4.granularity = granularity;
      scratchOptions$4.rotation = rotation;
      scratchOptions$4.semiMajorAxis = semiMajorAxis;
      scratchOptions$4.semiMinorAxis = semiMinorAxis;
      scratchOptions$4.numberOfVerticalLines = numberOfVerticalLines;
      scratchOptions$4.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;

      return new EllipseOutlineGeometry(scratchOptions$4);
    }

    result._center = Cartesian3.clone(center, result._center);
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._semiMajorAxis = semiMajorAxis;
    result._semiMinorAxis = semiMinorAxis;
    result._rotation = rotation;
    result._height = height;
    result._granularity = granularity;
    result._extrudedHeight = extrudedHeight;
    result._numberOfVerticalLines = numberOfVerticalLines;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of an outline of an ellipse on an ellipsoid, including its vertices, indices, and a bounding sphere.
   *
   * @param {EllipseOutlineGeometry} ellipseGeometry A description of the ellipse.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  EllipseOutlineGeometry.createGeometry = function (ellipseGeometry) {
    if (
      ellipseGeometry._semiMajorAxis <= 0.0 ||
      ellipseGeometry._semiMinorAxis <= 0.0
    ) {
      return;
    }

    var height = ellipseGeometry._height;
    var extrudedHeight = ellipseGeometry._extrudedHeight;
    var extrude = !CesiumMath.equalsEpsilon(
      height,
      extrudedHeight,
      0,
      CesiumMath.EPSILON2
    );

    ellipseGeometry._center = ellipseGeometry._ellipsoid.scaleToGeodeticSurface(
      ellipseGeometry._center,
      ellipseGeometry._center
    );
    var options = {
      center: ellipseGeometry._center,
      semiMajorAxis: ellipseGeometry._semiMajorAxis,
      semiMinorAxis: ellipseGeometry._semiMinorAxis,
      ellipsoid: ellipseGeometry._ellipsoid,
      rotation: ellipseGeometry._rotation,
      height: height,
      granularity: ellipseGeometry._granularity,
      numberOfVerticalLines: ellipseGeometry._numberOfVerticalLines,
    };
    var geometry;
    if (extrude) {
      options.extrudedHeight = extrudedHeight;
      options.offsetAttribute = ellipseGeometry._offsetAttribute;
      geometry = computeExtrudedEllipse$1(options);
    } else {
      geometry = computeEllipse$1(options);

      if (defined(ellipseGeometry._offsetAttribute)) {
        var length = geometry.attributes.position.values.length;
        var applyOffset = new Uint8Array(length / 3);
        var offsetValue =
          ellipseGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
            ? 0
            : 1;
        arrayFill(applyOffset, offsetValue);
        geometry.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: applyOffset,
        });
      }
    }

    return new Geometry({
      attributes: geometry.attributes,
      indices: geometry.indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: geometry.boundingSphere,
      offsetAttribute: ellipseGeometry._offsetAttribute,
    });
  };

  /**
   * A description of the outline of a circle on the ellipsoid.
   *
   * @alias CircleOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.center The circle's center point in the fixed frame.
   * @param {Number} options.radius The radius in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid the circle will be on.
   * @param {Number} [options.height=0.0] The distance in meters between the circle and the ellipsoid surface.
   * @param {Number} [options.granularity=0.02] The angular distance between points on the circle in radians.
   * @param {Number} [options.extrudedHeight=0.0] The distance in meters between the circle's extruded face and the ellipsoid surface.
   * @param {Number} [options.numberOfVerticalLines=16] Number of lines to draw between the top and bottom of an extruded circle.
   *
   * @exception {DeveloperError} radius must be greater than zero.
   * @exception {DeveloperError} granularity must be greater than zero.
   *
   * @see CircleOutlineGeometry.createGeometry
   * @see Packable
   *
   * @example
   * // Create a circle.
   * var circle = new Cesium.CircleOutlineGeometry({
   *   center : Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883),
   *   radius : 100000.0
   * });
   * var geometry = Cesium.CircleOutlineGeometry.createGeometry(circle);
   */
  function CircleOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var radius = options.radius;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("radius", radius);
    //>>includeEnd('debug');

    var ellipseGeometryOptions = {
      center: options.center,
      semiMajorAxis: radius,
      semiMinorAxis: radius,
      ellipsoid: options.ellipsoid,
      height: options.height,
      extrudedHeight: options.extrudedHeight,
      granularity: options.granularity,
      numberOfVerticalLines: options.numberOfVerticalLines,
    };
    this._ellipseGeometry = new EllipseOutlineGeometry(ellipseGeometryOptions);
    this._workerName = "createCircleOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  CircleOutlineGeometry.packedLength = EllipseOutlineGeometry.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CircleOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CircleOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    //>>includeEnd('debug');
    return EllipseOutlineGeometry.pack(
      value._ellipseGeometry,
      array,
      startingIndex
    );
  };

  var scratchEllipseGeometry$1 = new EllipseOutlineGeometry({
    center: new Cartesian3(),
    semiMajorAxis: 1.0,
    semiMinorAxis: 1.0,
  });
  var scratchOptions$5 = {
    center: new Cartesian3(),
    radius: undefined,
    ellipsoid: Ellipsoid.clone(Ellipsoid.UNIT_SPHERE),
    height: undefined,
    extrudedHeight: undefined,
    granularity: undefined,
    numberOfVerticalLines: undefined,
    semiMajorAxis: undefined,
    semiMinorAxis: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CircleOutlineGeometry} [result] The object into which to store the result.
   * @returns {CircleOutlineGeometry} The modified result parameter or a new CircleOutlineGeometry instance if one was not provided.
   */
  CircleOutlineGeometry.unpack = function (array, startingIndex, result) {
    var ellipseGeometry = EllipseOutlineGeometry.unpack(
      array,
      startingIndex,
      scratchEllipseGeometry$1
    );
    scratchOptions$5.center = Cartesian3.clone(
      ellipseGeometry._center,
      scratchOptions$5.center
    );
    scratchOptions$5.ellipsoid = Ellipsoid.clone(
      ellipseGeometry._ellipsoid,
      scratchOptions$5.ellipsoid
    );
    scratchOptions$5.height = ellipseGeometry._height;
    scratchOptions$5.extrudedHeight = ellipseGeometry._extrudedHeight;
    scratchOptions$5.granularity = ellipseGeometry._granularity;
    scratchOptions$5.numberOfVerticalLines = ellipseGeometry._numberOfVerticalLines;

    if (!defined(result)) {
      scratchOptions$5.radius = ellipseGeometry._semiMajorAxis;
      return new CircleOutlineGeometry(scratchOptions$5);
    }

    scratchOptions$5.semiMajorAxis = ellipseGeometry._semiMajorAxis;
    scratchOptions$5.semiMinorAxis = ellipseGeometry._semiMinorAxis;
    result._ellipseGeometry = new EllipseOutlineGeometry(scratchOptions$5);
    return result;
  };

  /**
   * Computes the geometric representation of an outline of a circle on an ellipsoid, including its vertices, indices, and a bounding sphere.
   *
   * @param {CircleOutlineGeometry} circleGeometry A description of the circle.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CircleOutlineGeometry.createGeometry = function (circleGeometry) {
    return EllipseOutlineGeometry.createGeometry(circleGeometry._ellipseGeometry);
  };

  /**
   * Constants used by {@link Clock#tick} to determine behavior
   * when {@link Clock#startTime} or {@link Clock#stopTime} is reached.
   *
   * @enum {Number}
   *
   * @see Clock
   * @see ClockStep
   */
  var ClockRange = {
    /**
     * {@link Clock#tick} will always advances the clock in its current direction.
     *
     * @type {Number}
     * @constant
     */
    UNBOUNDED: 0,

    /**
     * When {@link Clock#startTime} or {@link Clock#stopTime} is reached,
     * {@link Clock#tick} will not advance {@link Clock#currentTime} any further.
     *
     * @type {Number}
     * @constant
     */
    CLAMPED: 1,

    /**
     * When {@link Clock#stopTime} is reached, {@link Clock#tick} will advance
     * {@link Clock#currentTime} to the opposite end of the interval.  When
     * time is moving backwards, {@link Clock#tick} will not advance past
     * {@link Clock#startTime}
     *
     * @type {Number}
     * @constant
     */
    LOOP_STOP: 2,
  };
  var ClockRange$1 = Object.freeze(ClockRange);

  /**
   * Constants to determine how much time advances with each call
   * to {@link Clock#tick}.
   *
   * @enum {Number}
   *
   * @see Clock
   * @see ClockRange
   */
  var ClockStep = {
    /**
     * {@link Clock#tick} advances the current time by a fixed step,
     * which is the number of seconds specified by {@link Clock#multiplier}.
     *
     * @type {Number}
     * @constant
     */
    TICK_DEPENDENT: 0,

    /**
     * {@link Clock#tick} advances the current time by the amount of system
     * time elapsed since the previous call multiplied by {@link Clock#multiplier}.
     *
     * @type {Number}
     * @constant
     */
    SYSTEM_CLOCK_MULTIPLIER: 1,

    /**
     * {@link Clock#tick} sets the clock to the current system time;
     * ignoring all other settings.
     *
     * @type {Number}
     * @constant
     */
    SYSTEM_CLOCK: 2,
  };
  var ClockStep$1 = Object.freeze(ClockStep);

  /**
   * Gets a timestamp that can be used in measuring the time between events.  Timestamps
   * are expressed in milliseconds, but it is not specified what the milliseconds are
   * measured from.  This function uses performance.now() if it is available, or Date.now()
   * otherwise.
   *
   * @function getTimestamp
   *
   * @returns {Number} The timestamp in milliseconds since some unspecified reference time.
   */
  var getTimestamp;

  if (
    typeof performance !== "undefined" &&
    typeof performance.now === "function" &&
    isFinite(performance.now())
  ) {
    getTimestamp = function () {
      return performance.now();
    };
  } else {
    getTimestamp = function () {
      return Date.now();
    };
  }
  var getTimestamp$1 = getTimestamp;

  /**
   * A simple clock for keeping track of simulated time.
   *
   * @alias Clock
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {JulianDate} [options.startTime] The start time of the clock.
   * @param {JulianDate} [options.stopTime] The stop time of the clock.
   * @param {JulianDate} [options.currentTime] The current time.
   * @param {Number} [options.multiplier=1.0] Determines how much time advances when {@link Clock#tick} is called, negative values allow for advancing backwards.
   * @param {ClockStep} [options.clockStep=ClockStep.SYSTEM_CLOCK_MULTIPLIER] Determines if calls to {@link Clock#tick} are frame dependent or system clock dependent.
   * @param {ClockRange} [options.clockRange=ClockRange.UNBOUNDED] Determines how the clock should behave when {@link Clock#startTime} or {@link Clock#stopTime} is reached.
   * @param {Boolean} [options.canAnimate=true] Indicates whether {@link Clock#tick} can advance time.  This could be false if data is being buffered, for example.  The clock will only tick when both {@link Clock#canAnimate} and {@link Clock#shouldAnimate} are true.
   * @param {Boolean} [options.shouldAnimate=false] Indicates whether {@link Clock#tick} should attempt to advance time.  The clock will only tick when both {@link Clock#canAnimate} and {@link Clock#shouldAnimate} are true.
   *
   * @exception {DeveloperError} startTime must come before stopTime.
   *
   *
   * @example
   * // Create a clock that loops on Christmas day 2013 and runs in real-time.
   * var clock = new Cesium.Clock({
   *    startTime : Cesium.JulianDate.fromIso8601("2013-12-25"),
   *    currentTime : Cesium.JulianDate.fromIso8601("2013-12-25"),
   *    stopTime : Cesium.JulianDate.fromIso8601("2013-12-26"),
   *    clockRange : Cesium.ClockRange.LOOP_STOP,
   *    clockStep : Cesium.ClockStep.SYSTEM_CLOCK_MULTIPLIER
   * });
   *
   * @see ClockStep
   * @see ClockRange
   * @see JulianDate
   */
  function Clock(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var currentTime = options.currentTime;
    var startTime = options.startTime;
    var stopTime = options.stopTime;

    if (!defined(currentTime)) {
      // if not specified, current time is the start time,
      // or if that is not specified, 1 day before the stop time,
      // or if that is not specified, then now.
      if (defined(startTime)) {
        currentTime = JulianDate.clone(startTime);
      } else if (defined(stopTime)) {
        currentTime = JulianDate.addDays(stopTime, -1.0, new JulianDate());
      } else {
        currentTime = JulianDate.now();
      }
    } else {
      currentTime = JulianDate.clone(currentTime);
    }

    if (!defined(startTime)) {
      // if not specified, start time is the current time
      // (as determined above)
      startTime = JulianDate.clone(currentTime);
    } else {
      startTime = JulianDate.clone(startTime);
    }

    if (!defined(stopTime)) {
      // if not specified, stop time is 1 day after the start time
      // (as determined above)
      stopTime = JulianDate.addDays(startTime, 1.0, new JulianDate());
    } else {
      stopTime = JulianDate.clone(stopTime);
    }

    //>>includeStart('debug', pragmas.debug);
    if (JulianDate.greaterThan(startTime, stopTime)) {
      throw new DeveloperError("startTime must come before stopTime.");
    }
    //>>includeEnd('debug');

    /**
     * The start time of the clock.
     * @type {JulianDate}
     */
    this.startTime = startTime;

    /**
     * The stop time of the clock.
     * @type {JulianDate}
     */
    this.stopTime = stopTime;

    /**
     * Determines how the clock should behave when
     * {@link Clock#startTime} or {@link Clock#stopTime}
     * is reached.
     * @type {ClockRange}
     * @default {@link ClockRange.UNBOUNDED}
     */
    this.clockRange = defaultValue(options.clockRange, ClockRange$1.UNBOUNDED);

    /**
     * Indicates whether {@link Clock#tick} can advance time.  This could be false if data is being buffered,
     * for example.  The clock will only advance time when both
     * {@link Clock#canAnimate} and {@link Clock#shouldAnimate} are true.
     * @type {Boolean}
     * @default true
     */
    this.canAnimate = defaultValue(options.canAnimate, true);

    /**
     * An {@link Event} that is fired whenever {@link Clock#tick} is called.
     * @type {Event}
     */
    this.onTick = new Event();
    /**
     * An {@link Event} that is fired whenever {@link Clock#stopTime} is reached.
     * @type {Event}
     */
    this.onStop = new Event();

    this._currentTime = undefined;
    this._multiplier = undefined;
    this._clockStep = undefined;
    this._shouldAnimate = undefined;
    this._lastSystemTime = getTimestamp$1();

    // set values using the property setters to
    // make values consistent.

    this.currentTime = currentTime;
    this.multiplier = defaultValue(options.multiplier, 1.0);
    this.shouldAnimate = defaultValue(options.shouldAnimate, false);
    this.clockStep = defaultValue(
      options.clockStep,
      ClockStep$1.SYSTEM_CLOCK_MULTIPLIER
    );
  }

  Object.defineProperties(Clock.prototype, {
    /**
     * The current time.
     * Changing this property will change
     * {@link Clock#clockStep} from {@link ClockStep.SYSTEM_CLOCK} to
     * {@link ClockStep.SYSTEM_CLOCK_MULTIPLIER}.
     * @memberof Clock.prototype
     * @type {JulianDate}
     */
    currentTime: {
      get: function () {
        return this._currentTime;
      },
      set: function (value) {
        if (JulianDate.equals(this._currentTime, value)) {
          return;
        }

        if (this._clockStep === ClockStep$1.SYSTEM_CLOCK) {
          this._clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;
        }

        this._currentTime = value;
      },
    },

    /**
     * Gets or sets how much time advances when {@link Clock#tick} is called. Negative values allow for advancing backwards.
     * If {@link Clock#clockStep} is set to {@link ClockStep.TICK_DEPENDENT}, this is the number of seconds to advance.
     * If {@link Clock#clockStep} is set to {@link ClockStep.SYSTEM_CLOCK_MULTIPLIER}, this value is multiplied by the
     * elapsed system time since the last call to {@link Clock#tick}.
     * Changing this property will change
     * {@link Clock#clockStep} from {@link ClockStep.SYSTEM_CLOCK} to
     * {@link ClockStep.SYSTEM_CLOCK_MULTIPLIER}.
     * @memberof Clock.prototype
     * @type {Number}
     * @default 1.0
     */
    multiplier: {
      get: function () {
        return this._multiplier;
      },
      set: function (value) {
        if (this._multiplier === value) {
          return;
        }

        if (this._clockStep === ClockStep$1.SYSTEM_CLOCK) {
          this._clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;
        }

        this._multiplier = value;
      },
    },

    /**
     * Determines if calls to {@link Clock#tick} are frame dependent or system clock dependent.
     * Changing this property to {@link ClockStep.SYSTEM_CLOCK} will set
     * {@link Clock#multiplier} to 1.0, {@link Clock#shouldAnimate} to true, and
     * {@link Clock#currentTime} to the current system clock time.
     * @memberof Clock.prototype
     * @type ClockStep
     * @default {@link ClockStep.SYSTEM_CLOCK_MULTIPLIER}
     */
    clockStep: {
      get: function () {
        return this._clockStep;
      },
      set: function (value) {
        if (value === ClockStep$1.SYSTEM_CLOCK) {
          this._multiplier = 1.0;
          this._shouldAnimate = true;
          this._currentTime = JulianDate.now();
        }

        this._clockStep = value;
      },
    },

    /**
     * Indicates whether {@link Clock#tick} should attempt to advance time.
     * The clock will only advance time when both
     * {@link Clock#canAnimate} and {@link Clock#shouldAnimate} are true.
     * Changing this property will change
     * {@link Clock#clockStep} from {@link ClockStep.SYSTEM_CLOCK} to
     * {@link ClockStep.SYSTEM_CLOCK_MULTIPLIER}.
     * @memberof Clock.prototype
     * @type {Boolean}
     * @default false
     */
    shouldAnimate: {
      get: function () {
        return this._shouldAnimate;
      },
      set: function (value) {
        if (this._shouldAnimate === value) {
          return;
        }

        if (this._clockStep === ClockStep$1.SYSTEM_CLOCK) {
          this._clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;
        }

        this._shouldAnimate = value;
      },
    },
  });

  /**
   * Advances the clock from the current time based on the current configuration options.
   * tick should be called every frame, regardless of whether animation is taking place
   * or not.  To control animation, use the {@link Clock#shouldAnimate} property.
   *
   * @returns {JulianDate} The new value of the {@link Clock#currentTime} property.
   */
  Clock.prototype.tick = function () {
    var currentSystemTime = getTimestamp$1();
    var currentTime = JulianDate.clone(this._currentTime);

    if (this.canAnimate && this._shouldAnimate) {
      var clockStep = this._clockStep;
      if (clockStep === ClockStep$1.SYSTEM_CLOCK) {
        currentTime = JulianDate.now(currentTime);
      } else {
        var multiplier = this._multiplier;

        if (clockStep === ClockStep$1.TICK_DEPENDENT) {
          currentTime = JulianDate.addSeconds(
            currentTime,
            multiplier,
            currentTime
          );
        } else {
          var milliseconds = currentSystemTime - this._lastSystemTime;
          currentTime = JulianDate.addSeconds(
            currentTime,
            multiplier * (milliseconds / 1000.0),
            currentTime
          );
        }

        var clockRange = this.clockRange;
        var startTime = this.startTime;
        var stopTime = this.stopTime;

        if (clockRange === ClockRange$1.CLAMPED) {
          if (JulianDate.lessThan(currentTime, startTime)) {
            currentTime = JulianDate.clone(startTime, currentTime);
          } else if (JulianDate.greaterThan(currentTime, stopTime)) {
            currentTime = JulianDate.clone(stopTime, currentTime);
            this.onStop.raiseEvent(this);
          }
        } else if (clockRange === ClockRange$1.LOOP_STOP) {
          if (JulianDate.lessThan(currentTime, startTime)) {
            currentTime = JulianDate.clone(startTime, currentTime);
          }
          while (JulianDate.greaterThan(currentTime, stopTime)) {
            currentTime = JulianDate.addSeconds(
              startTime,
              JulianDate.secondsDifference(currentTime, stopTime),
              currentTime
            );
            this.onStop.raiseEvent(this);
          }
        }
      }
    }

    this._currentTime = currentTime;
    this._lastSystemTime = currentSystemTime;
    this.onTick.raiseEvent(this);
    return currentTime;
  };

  function hue2rgb(m1, m2, h) {
    if (h < 0) {
      h += 1;
    }
    if (h > 1) {
      h -= 1;
    }
    if (h * 6 < 1) {
      return m1 + (m2 - m1) * 6 * h;
    }
    if (h * 2 < 1) {
      return m2;
    }
    if (h * 3 < 2) {
      return m1 + (m2 - m1) * (2 / 3 - h) * 6;
    }
    return m1;
  }

  /**
   * A color, specified using red, green, blue, and alpha values,
   * which range from <code>0</code> (no intensity) to <code>1.0</code> (full intensity).
   * @param {Number} [red=1.0] The red component.
   * @param {Number} [green=1.0] The green component.
   * @param {Number} [blue=1.0] The blue component.
   * @param {Number} [alpha=1.0] The alpha component.
   *
   * @constructor
   * @alias Color
   *
   * @see Packable
   */
  function Color(red, green, blue, alpha) {
    /**
     * The red component.
     * @type {Number}
     * @default 1.0
     */
    this.red = defaultValue(red, 1.0);
    /**
     * The green component.
     * @type {Number}
     * @default 1.0
     */
    this.green = defaultValue(green, 1.0);
    /**
     * The blue component.
     * @type {Number}
     * @default 1.0
     */
    this.blue = defaultValue(blue, 1.0);
    /**
     * The alpha component.
     * @type {Number}
     * @default 1.0
     */
    this.alpha = defaultValue(alpha, 1.0);
  }

  /**
   * Creates a Color instance from a {@link Cartesian4}. <code>x</code>, <code>y</code>, <code>z</code>,
   * and <code>w</code> map to <code>red</code>, <code>green</code>, <code>blue</code>, and <code>alpha</code>, respectively.
   *
   * @param {Cartesian4} cartesian The source cartesian.
   * @param {Color} [result] The object onto which to store the result.
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   */
  Color.fromCartesian4 = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian", cartesian);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Color(cartesian.x, cartesian.y, cartesian.z, cartesian.w);
    }

    result.red = cartesian.x;
    result.green = cartesian.y;
    result.blue = cartesian.z;
    result.alpha = cartesian.w;
    return result;
  };

  /**
   * Creates a new Color specified using red, green, blue, and alpha values
   * that are in the range of 0 to 255, converting them internally to a range of 0.0 to 1.0.
   *
   * @param {Number} [red=255] The red component.
   * @param {Number} [green=255] The green component.
   * @param {Number} [blue=255] The blue component.
   * @param {Number} [alpha=255] The alpha component.
   * @param {Color} [result] The object onto which to store the result.
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   */
  Color.fromBytes = function (red, green, blue, alpha, result) {
    red = Color.byteToFloat(defaultValue(red, 255.0));
    green = Color.byteToFloat(defaultValue(green, 255.0));
    blue = Color.byteToFloat(defaultValue(blue, 255.0));
    alpha = Color.byteToFloat(defaultValue(alpha, 255.0));

    if (!defined(result)) {
      return new Color(red, green, blue, alpha);
    }

    result.red = red;
    result.green = green;
    result.blue = blue;
    result.alpha = alpha;
    return result;
  };

  /**
   * Creates a new Color that has the same red, green, and blue components
   * of the specified color, but with the specified alpha value.
   *
   * @param {Color} color The base color
   * @param {Number} alpha The new alpha component.
   * @param {Color} [result] The object onto which to store the result.
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   *
   * @example var translucentRed = Cesium.Color.fromAlpha(Cesium.Color.RED, 0.9);
   */
  Color.fromAlpha = function (color, alpha, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("color", color);
    Check.typeOf.number("alpha", alpha);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Color(color.red, color.green, color.blue, alpha);
    }

    result.red = color.red;
    result.green = color.green;
    result.blue = color.blue;
    result.alpha = alpha;
    return result;
  };

  var scratchArrayBuffer;
  var scratchUint32Array;
  var scratchUint8Array;
  if (FeatureDetection.supportsTypedArrays()) {
    scratchArrayBuffer = new ArrayBuffer(4);
    scratchUint32Array = new Uint32Array(scratchArrayBuffer);
    scratchUint8Array = new Uint8Array(scratchArrayBuffer);
  }

  /**
   * Creates a new Color from a single numeric unsigned 32-bit RGBA value, using the endianness
   * of the system.
   *
   * @param {Number} rgba A single numeric unsigned 32-bit RGBA value.
   * @param {Color} [result] The object to store the result in, if undefined a new instance will be created.
   * @returns {Color} The color object.
   *
   * @example
   * var color = Cesium.Color.fromRgba(0x67ADDFFF);
   *
   * @see Color#toRgba
   */
  Color.fromRgba = function (rgba, result) {
    // scratchUint32Array and scratchUint8Array share an underlying array buffer
    scratchUint32Array[0] = rgba;
    return Color.fromBytes(
      scratchUint8Array[0],
      scratchUint8Array[1],
      scratchUint8Array[2],
      scratchUint8Array[3],
      result
    );
  };

  /**
   * Creates a Color instance from hue, saturation, and lightness.
   *
   * @param {Number} [hue=0] The hue angle 0...1
   * @param {Number} [saturation=0] The saturation value 0...1
   * @param {Number} [lightness=0] The lightness value 0...1
   * @param {Number} [alpha=1.0] The alpha component 0...1
   * @param {Color} [result] The object to store the result in, if undefined a new instance will be created.
   * @returns {Color} The color object.
   *
   * @see {@link http://www.w3.org/TR/css3-color/#hsl-color|CSS color values}
   */
  Color.fromHsl = function (hue, saturation, lightness, alpha, result) {
    hue = defaultValue(hue, 0.0) % 1.0;
    saturation = defaultValue(saturation, 0.0);
    lightness = defaultValue(lightness, 0.0);
    alpha = defaultValue(alpha, 1.0);

    var red = lightness;
    var green = lightness;
    var blue = lightness;

    if (saturation !== 0) {
      var m2;
      if (lightness < 0.5) {
        m2 = lightness * (1 + saturation);
      } else {
        m2 = lightness + saturation - lightness * saturation;
      }

      var m1 = 2.0 * lightness - m2;
      red = hue2rgb(m1, m2, hue + 1 / 3);
      green = hue2rgb(m1, m2, hue);
      blue = hue2rgb(m1, m2, hue - 1 / 3);
    }

    if (!defined(result)) {
      return new Color(red, green, blue, alpha);
    }

    result.red = red;
    result.green = green;
    result.blue = blue;
    result.alpha = alpha;
    return result;
  };

  /**
   * Creates a random color using the provided options. For reproducible random colors, you should
   * call {@link CesiumMath#setRandomNumberSeed} once at the beginning of your application.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Number} [options.red] If specified, the red component to use instead of a randomized value.
   * @param {Number} [options.minimumRed=0.0] The maximum red value to generate if none was specified.
   * @param {Number} [options.maximumRed=1.0] The minimum red value to generate if none was specified.
   * @param {Number} [options.green] If specified, the green component to use instead of a randomized value.
   * @param {Number} [options.minimumGreen=0.0] The maximum green value to generate if none was specified.
   * @param {Number} [options.maximumGreen=1.0] The minimum green value to generate if none was specified.
   * @param {Number} [options.blue] If specified, the blue component to use instead of a randomized value.
   * @param {Number} [options.minimumBlue=0.0] The maximum blue value to generate if none was specified.
   * @param {Number} [options.maximumBlue=1.0] The minimum blue value to generate if none was specified.
   * @param {Number} [options.alpha] If specified, the alpha component to use instead of a randomized value.
   * @param {Number} [options.minimumAlpha=0.0] The maximum alpha value to generate if none was specified.
   * @param {Number} [options.maximumAlpha=1.0] The minimum alpha value to generate if none was specified.
   * @param {Color} [result] The object to store the result in, if undefined a new instance will be created.
   * @returns {Color} The modified result parameter or a new instance if result was undefined.
   *
   * @exception {DeveloperError} minimumRed must be less than or equal to maximumRed.
   * @exception {DeveloperError} minimumGreen must be less than or equal to maximumGreen.
   * @exception {DeveloperError} minimumBlue must be less than or equal to maximumBlue.
   * @exception {DeveloperError} minimumAlpha must be less than or equal to maximumAlpha.
   *
   * @example
   * //Create a completely random color
   * var color = Cesium.Color.fromRandom();
   *
   * //Create a random shade of yellow.
   * var color = Cesium.Color.fromRandom({
   *     red : 1.0,
   *     green : 1.0,
   *     alpha : 1.0
   * });
   *
   * //Create a random bright color.
   * var color = Cesium.Color.fromRandom({
   *     minimumRed : 0.75,
   *     minimumGreen : 0.75,
   *     minimumBlue : 0.75,
   *     alpha : 1.0
   * });
   */
  Color.fromRandom = function (options, result) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var red = options.red;
    if (!defined(red)) {
      var minimumRed = defaultValue(options.minimumRed, 0);
      var maximumRed = defaultValue(options.maximumRed, 1.0);

      //>>includeStart('debug', pragmas.debug);
      Check.typeOf.number.lessThanOrEquals("minimumRed", minimumRed, maximumRed);
      //>>includeEnd('debug');

      red =
        minimumRed + CesiumMath.nextRandomNumber() * (maximumRed - minimumRed);
    }

    var green = options.green;
    if (!defined(green)) {
      var minimumGreen = defaultValue(options.minimumGreen, 0);
      var maximumGreen = defaultValue(options.maximumGreen, 1.0);

      //>>includeStart('debug', pragmas.debug);
      Check.typeOf.number.lessThanOrEquals(
        "minimumGreen",
        minimumGreen,
        maximumGreen
      );
      //>>includeEnd('debug');
      green =
        minimumGreen +
        CesiumMath.nextRandomNumber() * (maximumGreen - minimumGreen);
    }

    var blue = options.blue;
    if (!defined(blue)) {
      var minimumBlue = defaultValue(options.minimumBlue, 0);
      var maximumBlue = defaultValue(options.maximumBlue, 1.0);

      //>>includeStart('debug', pragmas.debug);
      Check.typeOf.number.lessThanOrEquals(
        "minimumBlue",
        minimumBlue,
        maximumBlue
      );
      //>>includeEnd('debug');

      blue =
        minimumBlue + CesiumMath.nextRandomNumber() * (maximumBlue - minimumBlue);
    }

    var alpha = options.alpha;
    if (!defined(alpha)) {
      var minimumAlpha = defaultValue(options.minimumAlpha, 0);
      var maximumAlpha = defaultValue(options.maximumAlpha, 1.0);

      //>>includeStart('debug', pragmas.debug);
      Check.typeOf.number.lessThanOrEquals(
        "minumumAlpha",
        minimumAlpha,
        maximumAlpha
      );
      //>>includeEnd('debug');

      alpha =
        minimumAlpha +
        CesiumMath.nextRandomNumber() * (maximumAlpha - minimumAlpha);
    }

    if (!defined(result)) {
      return new Color(red, green, blue, alpha);
    }

    result.red = red;
    result.green = green;
    result.blue = blue;
    result.alpha = alpha;
    return result;
  };

  //#rgba
  var rgbaMatcher = /^#([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])?$/i;
  //#rrggbbaa
  var rrggbbaaMatcher = /^#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})?$/i;
  //rgb(), rgba(), or rgb%()
  var rgbParenthesesMatcher = /^rgba?\(\s*([0-9.]+%?)\s*,\s*([0-9.]+%?)\s*,\s*([0-9.]+%?)(?:\s*,\s*([0-9.]+))?\s*\)$/i;
  //hsl() or hsla()
  var hslParenthesesMatcher = /^hsla?\(\s*([0-9.]+)\s*,\s*([0-9.]+%)\s*,\s*([0-9.]+%)(?:\s*,\s*([0-9.]+))?\s*\)$/i;

  /**
   * Creates a Color instance from a CSS color value.
   *
   * @param {String} color The CSS color value in #rgb, #rgba, #rrggbb, #rrggbbaa, rgb(), rgba(), hsl(), or hsla() format.
   * @param {Color} [result] The object to store the result in, if undefined a new instance will be created.
   * @returns {Color} The color object, or undefined if the string was not a valid CSS color.
   *
   *
   * @example
   * var cesiumBlue = Cesium.Color.fromCssColorString('#67ADDF');
   * var green = Cesium.Color.fromCssColorString('green');
   *
   * @see {@link http://www.w3.org/TR/css3-color|CSS color values}
   */
  Color.fromCssColorString = function (color, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("color", color);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Color();
    }

    // Remove all whitespaces from the color string
    color = color.replace(/\s/g, "");

    var namedColor = Color[color.toUpperCase()];
    if (defined(namedColor)) {
      Color.clone(namedColor, result);
      return result;
    }

    var matches = rgbaMatcher.exec(color);
    if (matches !== null) {
      result.red = parseInt(matches[1], 16) / 15;
      result.green = parseInt(matches[2], 16) / 15.0;
      result.blue = parseInt(matches[3], 16) / 15.0;
      result.alpha = parseInt(defaultValue(matches[4], "f"), 16) / 15.0;
      return result;
    }

    matches = rrggbbaaMatcher.exec(color);
    if (matches !== null) {
      result.red = parseInt(matches[1], 16) / 255.0;
      result.green = parseInt(matches[2], 16) / 255.0;
      result.blue = parseInt(matches[3], 16) / 255.0;
      result.alpha = parseInt(defaultValue(matches[4], "ff"), 16) / 255.0;
      return result;
    }

    matches = rgbParenthesesMatcher.exec(color);
    if (matches !== null) {
      result.red =
        parseFloat(matches[1]) / ("%" === matches[1].substr(-1) ? 100.0 : 255.0);
      result.green =
        parseFloat(matches[2]) / ("%" === matches[2].substr(-1) ? 100.0 : 255.0);
      result.blue =
        parseFloat(matches[3]) / ("%" === matches[3].substr(-1) ? 100.0 : 255.0);
      result.alpha = parseFloat(defaultValue(matches[4], "1.0"));
      return result;
    }

    matches = hslParenthesesMatcher.exec(color);
    if (matches !== null) {
      return Color.fromHsl(
        parseFloat(matches[1]) / 360.0,
        parseFloat(matches[2]) / 100.0,
        parseFloat(matches[3]) / 100.0,
        parseFloat(defaultValue(matches[4], "1.0")),
        result
      );
    }

    result = undefined;
    return result;
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  Color.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {Color} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  Color.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);
    array[startingIndex++] = value.red;
    array[startingIndex++] = value.green;
    array[startingIndex++] = value.blue;
    array[startingIndex] = value.alpha;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {Color} [result] The object into which to store the result.
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   */
  Color.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);
    if (!defined(result)) {
      result = new Color();
    }
    result.red = array[startingIndex++];
    result.green = array[startingIndex++];
    result.blue = array[startingIndex++];
    result.alpha = array[startingIndex];
    return result;
  };

  /**
   * Converts a 'byte' color component in the range of 0 to 255 into
   * a 'float' color component in the range of 0 to 1.0.
   *
   * @param {Number} number The number to be converted.
   * @returns {Number} The converted number.
   */
  Color.byteToFloat = function (number) {
    return number / 255.0;
  };

  /**
   * Converts a 'float' color component in the range of 0 to 1.0 into
   * a 'byte' color component in the range of 0 to 255.
   *
   * @param {Number} number The number to be converted.
   * @returns {Number} The converted number.
   */
  Color.floatToByte = function (number) {
    return number === 1.0 ? 255.0 : (number * 256.0) | 0;
  };

  /**
   * Duplicates a Color.
   *
   * @param {Color} color The Color to duplicate.
   * @param {Color} [result] The object to store the result in, if undefined a new instance will be created.
   * @returns {Color} The modified result parameter or a new instance if result was undefined. (Returns undefined if color is undefined)
   */
  Color.clone = function (color, result) {
    if (!defined(color)) {
      return undefined;
    }
    if (!defined(result)) {
      return new Color(color.red, color.green, color.blue, color.alpha);
    }
    result.red = color.red;
    result.green = color.green;
    result.blue = color.blue;
    result.alpha = color.alpha;
    return result;
  };

  /**
   * Returns true if the first Color equals the second color.
   *
   * @param {Color} left The first Color to compare for equality.
   * @param {Color} right The second Color to compare for equality.
   * @returns {Boolean} <code>true</code> if the Colors are equal; otherwise, <code>false</code>.
   */
  Color.equals = function (left, right) {
    return (
      left === right || //
      (defined(left) && //
      defined(right) && //
      left.red === right.red && //
      left.green === right.green && //
      left.blue === right.blue && //
        left.alpha === right.alpha)
    );
  };

  /**
   * @private
   */
  Color.equalsArray = function (color, array, offset) {
    return (
      color.red === array[offset] &&
      color.green === array[offset + 1] &&
      color.blue === array[offset + 2] &&
      color.alpha === array[offset + 3]
    );
  };

  /**
   * Returns a duplicate of a Color instance.
   *
   * @param {Color} [result] The object to store the result in, if undefined a new instance will be created.
   * @returns {Color} The modified result parameter or a new instance if result was undefined.
   */
  Color.prototype.clone = function (result) {
    return Color.clone(this, result);
  };

  /**
   * Returns true if this Color equals other.
   *
   * @param {Color} other The Color to compare for equality.
   * @returns {Boolean} <code>true</code> if the Colors are equal; otherwise, <code>false</code>.
   */
  Color.prototype.equals = function (other) {
    return Color.equals(this, other);
  };

  /**
   * Returns <code>true</code> if this Color equals other componentwise within the specified epsilon.
   *
   * @param {Color} other The Color to compare for equality.
   * @param {Number} [epsilon=0.0] The epsilon to use for equality testing.
   * @returns {Boolean} <code>true</code> if the Colors are equal within the specified epsilon; otherwise, <code>false</code>.
   */
  Color.prototype.equalsEpsilon = function (other, epsilon) {
    return (
      this === other || //
      (defined(other) && //
      Math.abs(this.red - other.red) <= epsilon && //
      Math.abs(this.green - other.green) <= epsilon && //
      Math.abs(this.blue - other.blue) <= epsilon && //
        Math.abs(this.alpha - other.alpha) <= epsilon)
    );
  };

  /**
   * Creates a string representing this Color in the format '(red, green, blue, alpha)'.
   *
   * @returns {String} A string representing this Color in the format '(red, green, blue, alpha)'.
   */
  Color.prototype.toString = function () {
    return (
      "(" +
      this.red +
      ", " +
      this.green +
      ", " +
      this.blue +
      ", " +
      this.alpha +
      ")"
    );
  };

  /**
   * Creates a string containing the CSS color value for this color.
   *
   * @returns {String} The CSS equivalent of this color.
   *
   * @see {@link http://www.w3.org/TR/css3-color/#rgba-color|CSS RGB or RGBA color values}
   */
  Color.prototype.toCssColorString = function () {
    var red = Color.floatToByte(this.red);
    var green = Color.floatToByte(this.green);
    var blue = Color.floatToByte(this.blue);
    if (this.alpha === 1) {
      return "rgb(" + red + "," + green + "," + blue + ")";
    }
    return "rgba(" + red + "," + green + "," + blue + "," + this.alpha + ")";
  };

  /**
   * Creates a string containing CSS hex string color value for this color.
   *
   * @returns {String} The CSS hex string equivalent of this color.
   */
  Color.prototype.toCssHexString = function () {
    var r = Color.floatToByte(this.red).toString(16);
    if (r.length < 2) {
      r = "0" + r;
    }
    var g = Color.floatToByte(this.green).toString(16);
    if (g.length < 2) {
      g = "0" + g;
    }
    var b = Color.floatToByte(this.blue).toString(16);
    if (b.length < 2) {
      b = "0" + b;
    }
    if (this.alpha < 1) {
      var hexAlpha = Color.floatToByte(this.alpha).toString(16);
      if (hexAlpha.length < 2) {
        hexAlpha = "0" + hexAlpha;
      }
      return "#" + r + g + b + hexAlpha;
    }
    return "#" + r + g + b;
  };

  /**
   * Converts this color to an array of red, green, blue, and alpha values
   * that are in the range of 0 to 255.
   *
   * @param {Number[]} [result] The array to store the result in, if undefined a new instance will be created.
   * @returns {Number[]} The modified result parameter or a new instance if result was undefined.
   */
  Color.prototype.toBytes = function (result) {
    var red = Color.floatToByte(this.red);
    var green = Color.floatToByte(this.green);
    var blue = Color.floatToByte(this.blue);
    var alpha = Color.floatToByte(this.alpha);

    if (!defined(result)) {
      return [red, green, blue, alpha];
    }
    result[0] = red;
    result[1] = green;
    result[2] = blue;
    result[3] = alpha;
    return result;
  };

  /**
   * Converts this color to a single numeric unsigned 32-bit RGBA value, using the endianness
   * of the system.
   *
   * @returns {Number} A single numeric unsigned 32-bit RGBA value.
   *
   *
   * @example
   * var rgba = Cesium.Color.BLUE.toRgba();
   *
   * @see Color.fromRgba
   */
  Color.prototype.toRgba = function () {
    // scratchUint32Array and scratchUint8Array share an underlying array buffer
    scratchUint8Array[0] = Color.floatToByte(this.red);
    scratchUint8Array[1] = Color.floatToByte(this.green);
    scratchUint8Array[2] = Color.floatToByte(this.blue);
    scratchUint8Array[3] = Color.floatToByte(this.alpha);
    return scratchUint32Array[0];
  };

  /**
   * Brightens this color by the provided magnitude.
   *
   * @param {Number} magnitude A positive number indicating the amount to brighten.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   *
   * @example
   * var brightBlue = Cesium.Color.BLUE.brighten(0.5, new Cesium.Color());
   */
  Color.prototype.brighten = function (magnitude, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("magnitude", magnitude);
    Check.typeOf.number.greaterThanOrEquals("magnitude", magnitude, 0.0);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    magnitude = 1.0 - magnitude;
    result.red = 1.0 - (1.0 - this.red) * magnitude;
    result.green = 1.0 - (1.0 - this.green) * magnitude;
    result.blue = 1.0 - (1.0 - this.blue) * magnitude;
    result.alpha = this.alpha;
    return result;
  };

  /**
   * Darkens this color by the provided magnitude.
   *
   * @param {Number} magnitude A positive number indicating the amount to darken.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   *
   * @example
   * var darkBlue = Cesium.Color.BLUE.darken(0.5, new Cesium.Color());
   */
  Color.prototype.darken = function (magnitude, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("magnitude", magnitude);
    Check.typeOf.number.greaterThanOrEquals("magnitude", magnitude, 0.0);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    magnitude = 1.0 - magnitude;
    result.red = this.red * magnitude;
    result.green = this.green * magnitude;
    result.blue = this.blue * magnitude;
    result.alpha = this.alpha;
    return result;
  };

  /**
   * Creates a new Color that has the same red, green, and blue components
   * as this Color, but with the specified alpha value.
   *
   * @param {Number} alpha The new alpha component.
   * @param {Color} [result] The object onto which to store the result.
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   *
   * @example var translucentRed = Cesium.Color.RED.withAlpha(0.9);
   */
  Color.prototype.withAlpha = function (alpha, result) {
    return Color.fromAlpha(this, alpha, result);
  };

  /**
   * Computes the componentwise sum of two Colors.
   *
   * @param {Color} left The first Color.
   * @param {Color} right The second Color.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.add = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = left.red + right.red;
    result.green = left.green + right.green;
    result.blue = left.blue + right.blue;
    result.alpha = left.alpha + right.alpha;
    return result;
  };

  /**
   * Computes the componentwise difference of two Colors.
   *
   * @param {Color} left The first Color.
   * @param {Color} right The second Color.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.subtract = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = left.red - right.red;
    result.green = left.green - right.green;
    result.blue = left.blue - right.blue;
    result.alpha = left.alpha - right.alpha;
    return result;
  };

  /**
   * Computes the componentwise product of two Colors.
   *
   * @param {Color} left The first Color.
   * @param {Color} right The second Color.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.multiply = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = left.red * right.red;
    result.green = left.green * right.green;
    result.blue = left.blue * right.blue;
    result.alpha = left.alpha * right.alpha;
    return result;
  };

  /**
   * Computes the componentwise quotient of two Colors.
   *
   * @param {Color} left The first Color.
   * @param {Color} right The second Color.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.divide = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = left.red / right.red;
    result.green = left.green / right.green;
    result.blue = left.blue / right.blue;
    result.alpha = left.alpha / right.alpha;
    return result;
  };

  /**
   * Computes the componentwise modulus of two Colors.
   *
   * @param {Color} left The first Color.
   * @param {Color} right The second Color.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.mod = function (left, right, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    Check.typeOf.object("right", right);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = left.red % right.red;
    result.green = left.green % right.green;
    result.blue = left.blue % right.blue;
    result.alpha = left.alpha % right.alpha;
    return result;
  };

  /**
   * Computes the linear interpolation or extrapolation at t between the provided colors.
   *
   * @param {Color} start The color corresponding to t at 0.0.
   * @param {Color} end The color corresponding to t at 1.0.
   * @param {Number} t The point along t at which to interpolate.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.lerp = function (start, end, t, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("start", start);
    Check.typeOf.object("end", end);
    Check.typeOf.number("t", t);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = CesiumMath.lerp(start.red, end.red, t);
    result.green = CesiumMath.lerp(start.green, end.green, t);
    result.blue = CesiumMath.lerp(start.blue, end.blue, t);
    result.alpha = CesiumMath.lerp(start.alpha, end.alpha, t);
    return result;
  };

  /**
   * Multiplies the provided Color componentwise by the provided scalar.
   *
   * @param {Color} color The Color to be scaled.
   * @param {Number} scalar The scalar to multiply with.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.multiplyByScalar = function (color, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("color", color);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = color.red * scalar;
    result.green = color.green * scalar;
    result.blue = color.blue * scalar;
    result.alpha = color.alpha * scalar;
    return result;
  };

  /**
   * Divides the provided Color componentwise by the provided scalar.
   *
   * @param {Color} color The Color to be divided.
   * @param {Number} scalar The scalar to divide with.
   * @param {Color} result The object onto which to store the result.
   * @returns {Color} The modified result parameter.
   */
  Color.divideByScalar = function (color, scalar, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("color", color);
    Check.typeOf.number("scalar", scalar);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    result.red = color.red / scalar;
    result.green = color.green / scalar;
    result.blue = color.blue / scalar;
    result.alpha = color.alpha / scalar;
    return result;
  };

  /**
   * An immutable Color instance initialized to CSS color #F0F8FF
   * <span class="colorSwath" style="background: #F0F8FF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ALICEBLUE = Object.freeze(Color.fromCssColorString("#F0F8FF"));

  /**
   * An immutable Color instance initialized to CSS color #FAEBD7
   * <span class="colorSwath" style="background: #FAEBD7;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ANTIQUEWHITE = Object.freeze(Color.fromCssColorString("#FAEBD7"));

  /**
   * An immutable Color instance initialized to CSS color #00FFFF
   * <span class="colorSwath" style="background: #00FFFF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.AQUA = Object.freeze(Color.fromCssColorString("#00FFFF"));

  /**
   * An immutable Color instance initialized to CSS color #7FFFD4
   * <span class="colorSwath" style="background: #7FFFD4;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.AQUAMARINE = Object.freeze(Color.fromCssColorString("#7FFFD4"));

  /**
   * An immutable Color instance initialized to CSS color #F0FFFF
   * <span class="colorSwath" style="background: #F0FFFF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.AZURE = Object.freeze(Color.fromCssColorString("#F0FFFF"));

  /**
   * An immutable Color instance initialized to CSS color #F5F5DC
   * <span class="colorSwath" style="background: #F5F5DC;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BEIGE = Object.freeze(Color.fromCssColorString("#F5F5DC"));

  /**
   * An immutable Color instance initialized to CSS color #FFE4C4
   * <span class="colorSwath" style="background: #FFE4C4;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BISQUE = Object.freeze(Color.fromCssColorString("#FFE4C4"));

  /**
   * An immutable Color instance initialized to CSS color #000000
   * <span class="colorSwath" style="background: #000000;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BLACK = Object.freeze(Color.fromCssColorString("#000000"));

  /**
   * An immutable Color instance initialized to CSS color #FFEBCD
   * <span class="colorSwath" style="background: #FFEBCD;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BLANCHEDALMOND = Object.freeze(Color.fromCssColorString("#FFEBCD"));

  /**
   * An immutable Color instance initialized to CSS color #0000FF
   * <span class="colorSwath" style="background: #0000FF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BLUE = Object.freeze(Color.fromCssColorString("#0000FF"));

  /**
   * An immutable Color instance initialized to CSS color #8A2BE2
   * <span class="colorSwath" style="background: #8A2BE2;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BLUEVIOLET = Object.freeze(Color.fromCssColorString("#8A2BE2"));

  /**
   * An immutable Color instance initialized to CSS color #A52A2A
   * <span class="colorSwath" style="background: #A52A2A;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BROWN = Object.freeze(Color.fromCssColorString("#A52A2A"));

  /**
   * An immutable Color instance initialized to CSS color #DEB887
   * <span class="colorSwath" style="background: #DEB887;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.BURLYWOOD = Object.freeze(Color.fromCssColorString("#DEB887"));

  /**
   * An immutable Color instance initialized to CSS color #5F9EA0
   * <span class="colorSwath" style="background: #5F9EA0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CADETBLUE = Object.freeze(Color.fromCssColorString("#5F9EA0"));
  /**
   * An immutable Color instance initialized to CSS color #7FFF00
   * <span class="colorSwath" style="background: #7FFF00;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CHARTREUSE = Object.freeze(Color.fromCssColorString("#7FFF00"));

  /**
   * An immutable Color instance initialized to CSS color #D2691E
   * <span class="colorSwath" style="background: #D2691E;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CHOCOLATE = Object.freeze(Color.fromCssColorString("#D2691E"));

  /**
   * An immutable Color instance initialized to CSS color #FF7F50
   * <span class="colorSwath" style="background: #FF7F50;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CORAL = Object.freeze(Color.fromCssColorString("#FF7F50"));

  /**
   * An immutable Color instance initialized to CSS color #6495ED
   * <span class="colorSwath" style="background: #6495ED;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CORNFLOWERBLUE = Object.freeze(Color.fromCssColorString("#6495ED"));

  /**
   * An immutable Color instance initialized to CSS color #FFF8DC
   * <span class="colorSwath" style="background: #FFF8DC;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CORNSILK = Object.freeze(Color.fromCssColorString("#FFF8DC"));

  /**
   * An immutable Color instance initialized to CSS color #DC143C
   * <span class="colorSwath" style="background: #DC143C;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CRIMSON = Object.freeze(Color.fromCssColorString("#DC143C"));

  /**
   * An immutable Color instance initialized to CSS color #00FFFF
   * <span class="colorSwath" style="background: #00FFFF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.CYAN = Object.freeze(Color.fromCssColorString("#00FFFF"));

  /**
   * An immutable Color instance initialized to CSS color #00008B
   * <span class="colorSwath" style="background: #00008B;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKBLUE = Object.freeze(Color.fromCssColorString("#00008B"));

  /**
   * An immutable Color instance initialized to CSS color #008B8B
   * <span class="colorSwath" style="background: #008B8B;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKCYAN = Object.freeze(Color.fromCssColorString("#008B8B"));

  /**
   * An immutable Color instance initialized to CSS color #B8860B
   * <span class="colorSwath" style="background: #B8860B;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKGOLDENROD = Object.freeze(Color.fromCssColorString("#B8860B"));

  /**
   * An immutable Color instance initialized to CSS color #A9A9A9
   * <span class="colorSwath" style="background: #A9A9A9;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKGRAY = Object.freeze(Color.fromCssColorString("#A9A9A9"));

  /**
   * An immutable Color instance initialized to CSS color #006400
   * <span class="colorSwath" style="background: #006400;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKGREEN = Object.freeze(Color.fromCssColorString("#006400"));

  /**
   * An immutable Color instance initialized to CSS color #A9A9A9
   * <span class="colorSwath" style="background: #A9A9A9;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKGREY = Color.DARKGRAY;

  /**
   * An immutable Color instance initialized to CSS color #BDB76B
   * <span class="colorSwath" style="background: #BDB76B;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKKHAKI = Object.freeze(Color.fromCssColorString("#BDB76B"));

  /**
   * An immutable Color instance initialized to CSS color #8B008B
   * <span class="colorSwath" style="background: #8B008B;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKMAGENTA = Object.freeze(Color.fromCssColorString("#8B008B"));

  /**
   * An immutable Color instance initialized to CSS color #556B2F
   * <span class="colorSwath" style="background: #556B2F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKOLIVEGREEN = Object.freeze(Color.fromCssColorString("#556B2F"));

  /**
   * An immutable Color instance initialized to CSS color #FF8C00
   * <span class="colorSwath" style="background: #FF8C00;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKORANGE = Object.freeze(Color.fromCssColorString("#FF8C00"));

  /**
   * An immutable Color instance initialized to CSS color #9932CC
   * <span class="colorSwath" style="background: #9932CC;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKORCHID = Object.freeze(Color.fromCssColorString("#9932CC"));

  /**
   * An immutable Color instance initialized to CSS color #8B0000
   * <span class="colorSwath" style="background: #8B0000;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKRED = Object.freeze(Color.fromCssColorString("#8B0000"));

  /**
   * An immutable Color instance initialized to CSS color #E9967A
   * <span class="colorSwath" style="background: #E9967A;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKSALMON = Object.freeze(Color.fromCssColorString("#E9967A"));

  /**
   * An immutable Color instance initialized to CSS color #8FBC8F
   * <span class="colorSwath" style="background: #8FBC8F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKSEAGREEN = Object.freeze(Color.fromCssColorString("#8FBC8F"));

  /**
   * An immutable Color instance initialized to CSS color #483D8B
   * <span class="colorSwath" style="background: #483D8B;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKSLATEBLUE = Object.freeze(Color.fromCssColorString("#483D8B"));

  /**
   * An immutable Color instance initialized to CSS color #2F4F4F
   * <span class="colorSwath" style="background: #2F4F4F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKSLATEGRAY = Object.freeze(Color.fromCssColorString("#2F4F4F"));

  /**
   * An immutable Color instance initialized to CSS color #2F4F4F
   * <span class="colorSwath" style="background: #2F4F4F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKSLATEGREY = Color.DARKSLATEGRAY;

  /**
   * An immutable Color instance initialized to CSS color #00CED1
   * <span class="colorSwath" style="background: #00CED1;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKTURQUOISE = Object.freeze(Color.fromCssColorString("#00CED1"));

  /**
   * An immutable Color instance initialized to CSS color #9400D3
   * <span class="colorSwath" style="background: #9400D3;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DARKVIOLET = Object.freeze(Color.fromCssColorString("#9400D3"));

  /**
   * An immutable Color instance initialized to CSS color #FF1493
   * <span class="colorSwath" style="background: #FF1493;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DEEPPINK = Object.freeze(Color.fromCssColorString("#FF1493"));

  /**
   * An immutable Color instance initialized to CSS color #00BFFF
   * <span class="colorSwath" style="background: #00BFFF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DEEPSKYBLUE = Object.freeze(Color.fromCssColorString("#00BFFF"));

  /**
   * An immutable Color instance initialized to CSS color #696969
   * <span class="colorSwath" style="background: #696969;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DIMGRAY = Object.freeze(Color.fromCssColorString("#696969"));

  /**
   * An immutable Color instance initialized to CSS color #696969
   * <span class="colorSwath" style="background: #696969;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DIMGREY = Color.DIMGRAY;

  /**
   * An immutable Color instance initialized to CSS color #1E90FF
   * <span class="colorSwath" style="background: #1E90FF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.DODGERBLUE = Object.freeze(Color.fromCssColorString("#1E90FF"));

  /**
   * An immutable Color instance initialized to CSS color #B22222
   * <span class="colorSwath" style="background: #B22222;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.FIREBRICK = Object.freeze(Color.fromCssColorString("#B22222"));

  /**
   * An immutable Color instance initialized to CSS color #FFFAF0
   * <span class="colorSwath" style="background: #FFFAF0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.FLORALWHITE = Object.freeze(Color.fromCssColorString("#FFFAF0"));

  /**
   * An immutable Color instance initialized to CSS color #228B22
   * <span class="colorSwath" style="background: #228B22;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.FORESTGREEN = Object.freeze(Color.fromCssColorString("#228B22"));

  /**
   * An immutable Color instance initialized to CSS color #FF00FF
   * <span class="colorSwath" style="background: #FF00FF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.FUCHSIA = Object.freeze(Color.fromCssColorString("#FF00FF"));

  /**
   * An immutable Color instance initialized to CSS color #DCDCDC
   * <span class="colorSwath" style="background: #DCDCDC;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GAINSBORO = Object.freeze(Color.fromCssColorString("#DCDCDC"));

  /**
   * An immutable Color instance initialized to CSS color #F8F8FF
   * <span class="colorSwath" style="background: #F8F8FF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GHOSTWHITE = Object.freeze(Color.fromCssColorString("#F8F8FF"));

  /**
   * An immutable Color instance initialized to CSS color #FFD700
   * <span class="colorSwath" style="background: #FFD700;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GOLD = Object.freeze(Color.fromCssColorString("#FFD700"));

  /**
   * An immutable Color instance initialized to CSS color #DAA520
   * <span class="colorSwath" style="background: #DAA520;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GOLDENROD = Object.freeze(Color.fromCssColorString("#DAA520"));

  /**
   * An immutable Color instance initialized to CSS color #808080
   * <span class="colorSwath" style="background: #808080;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GRAY = Object.freeze(Color.fromCssColorString("#808080"));

  /**
   * An immutable Color instance initialized to CSS color #008000
   * <span class="colorSwath" style="background: #008000;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GREEN = Object.freeze(Color.fromCssColorString("#008000"));

  /**
   * An immutable Color instance initialized to CSS color #ADFF2F
   * <span class="colorSwath" style="background: #ADFF2F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GREENYELLOW = Object.freeze(Color.fromCssColorString("#ADFF2F"));

  /**
   * An immutable Color instance initialized to CSS color #808080
   * <span class="colorSwath" style="background: #808080;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.GREY = Color.GRAY;

  /**
   * An immutable Color instance initialized to CSS color #F0FFF0
   * <span class="colorSwath" style="background: #F0FFF0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.HONEYDEW = Object.freeze(Color.fromCssColorString("#F0FFF0"));

  /**
   * An immutable Color instance initialized to CSS color #FF69B4
   * <span class="colorSwath" style="background: #FF69B4;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.HOTPINK = Object.freeze(Color.fromCssColorString("#FF69B4"));

  /**
   * An immutable Color instance initialized to CSS color #CD5C5C
   * <span class="colorSwath" style="background: #CD5C5C;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.INDIANRED = Object.freeze(Color.fromCssColorString("#CD5C5C"));

  /**
   * An immutable Color instance initialized to CSS color #4B0082
   * <span class="colorSwath" style="background: #4B0082;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.INDIGO = Object.freeze(Color.fromCssColorString("#4B0082"));

  /**
   * An immutable Color instance initialized to CSS color #FFFFF0
   * <span class="colorSwath" style="background: #FFFFF0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.IVORY = Object.freeze(Color.fromCssColorString("#FFFFF0"));

  /**
   * An immutable Color instance initialized to CSS color #F0E68C
   * <span class="colorSwath" style="background: #F0E68C;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.KHAKI = Object.freeze(Color.fromCssColorString("#F0E68C"));

  /**
   * An immutable Color instance initialized to CSS color #E6E6FA
   * <span class="colorSwath" style="background: #E6E6FA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LAVENDER = Object.freeze(Color.fromCssColorString("#E6E6FA"));

  /**
   * An immutable Color instance initialized to CSS color #FFF0F5
   * <span class="colorSwath" style="background: #FFF0F5;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LAVENDAR_BLUSH = Object.freeze(Color.fromCssColorString("#FFF0F5"));

  /**
   * An immutable Color instance initialized to CSS color #7CFC00
   * <span class="colorSwath" style="background: #7CFC00;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LAWNGREEN = Object.freeze(Color.fromCssColorString("#7CFC00"));

  /**
   * An immutable Color instance initialized to CSS color #FFFACD
   * <span class="colorSwath" style="background: #FFFACD;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LEMONCHIFFON = Object.freeze(Color.fromCssColorString("#FFFACD"));

  /**
   * An immutable Color instance initialized to CSS color #ADD8E6
   * <span class="colorSwath" style="background: #ADD8E6;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTBLUE = Object.freeze(Color.fromCssColorString("#ADD8E6"));

  /**
   * An immutable Color instance initialized to CSS color #F08080
   * <span class="colorSwath" style="background: #F08080;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTCORAL = Object.freeze(Color.fromCssColorString("#F08080"));

  /**
   * An immutable Color instance initialized to CSS color #E0FFFF
   * <span class="colorSwath" style="background: #E0FFFF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTCYAN = Object.freeze(Color.fromCssColorString("#E0FFFF"));

  /**
   * An immutable Color instance initialized to CSS color #FAFAD2
   * <span class="colorSwath" style="background: #FAFAD2;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTGOLDENRODYELLOW = Object.freeze(Color.fromCssColorString("#FAFAD2"));

  /**
   * An immutable Color instance initialized to CSS color #D3D3D3
   * <span class="colorSwath" style="background: #D3D3D3;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTGRAY = Object.freeze(Color.fromCssColorString("#D3D3D3"));

  /**
   * An immutable Color instance initialized to CSS color #90EE90
   * <span class="colorSwath" style="background: #90EE90;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTGREEN = Object.freeze(Color.fromCssColorString("#90EE90"));

  /**
   * An immutable Color instance initialized to CSS color #D3D3D3
   * <span class="colorSwath" style="background: #D3D3D3;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTGREY = Color.LIGHTGRAY;

  /**
   * An immutable Color instance initialized to CSS color #FFB6C1
   * <span class="colorSwath" style="background: #FFB6C1;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTPINK = Object.freeze(Color.fromCssColorString("#FFB6C1"));

  /**
   * An immutable Color instance initialized to CSS color #20B2AA
   * <span class="colorSwath" style="background: #20B2AA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTSEAGREEN = Object.freeze(Color.fromCssColorString("#20B2AA"));

  /**
   * An immutable Color instance initialized to CSS color #87CEFA
   * <span class="colorSwath" style="background: #87CEFA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTSKYBLUE = Object.freeze(Color.fromCssColorString("#87CEFA"));

  /**
   * An immutable Color instance initialized to CSS color #778899
   * <span class="colorSwath" style="background: #778899;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTSLATEGRAY = Object.freeze(Color.fromCssColorString("#778899"));

  /**
   * An immutable Color instance initialized to CSS color #778899
   * <span class="colorSwath" style="background: #778899;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTSLATEGREY = Color.LIGHTSLATEGRAY;

  /**
   * An immutable Color instance initialized to CSS color #B0C4DE
   * <span class="colorSwath" style="background: #B0C4DE;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTSTEELBLUE = Object.freeze(Color.fromCssColorString("#B0C4DE"));

  /**
   * An immutable Color instance initialized to CSS color #FFFFE0
   * <span class="colorSwath" style="background: #FFFFE0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIGHTYELLOW = Object.freeze(Color.fromCssColorString("#FFFFE0"));

  /**
   * An immutable Color instance initialized to CSS color #00FF00
   * <span class="colorSwath" style="background: #00FF00;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIME = Object.freeze(Color.fromCssColorString("#00FF00"));

  /**
   * An immutable Color instance initialized to CSS color #32CD32
   * <span class="colorSwath" style="background: #32CD32;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LIMEGREEN = Object.freeze(Color.fromCssColorString("#32CD32"));

  /**
   * An immutable Color instance initialized to CSS color #FAF0E6
   * <span class="colorSwath" style="background: #FAF0E6;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.LINEN = Object.freeze(Color.fromCssColorString("#FAF0E6"));

  /**
   * An immutable Color instance initialized to CSS color #FF00FF
   * <span class="colorSwath" style="background: #FF00FF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MAGENTA = Object.freeze(Color.fromCssColorString("#FF00FF"));

  /**
   * An immutable Color instance initialized to CSS color #800000
   * <span class="colorSwath" style="background: #800000;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MAROON = Object.freeze(Color.fromCssColorString("#800000"));

  /**
   * An immutable Color instance initialized to CSS color #66CDAA
   * <span class="colorSwath" style="background: #66CDAA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMAQUAMARINE = Object.freeze(Color.fromCssColorString("#66CDAA"));

  /**
   * An immutable Color instance initialized to CSS color #0000CD
   * <span class="colorSwath" style="background: #0000CD;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMBLUE = Object.freeze(Color.fromCssColorString("#0000CD"));

  /**
   * An immutable Color instance initialized to CSS color #BA55D3
   * <span class="colorSwath" style="background: #BA55D3;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMORCHID = Object.freeze(Color.fromCssColorString("#BA55D3"));

  /**
   * An immutable Color instance initialized to CSS color #9370DB
   * <span class="colorSwath" style="background: #9370DB;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMPURPLE = Object.freeze(Color.fromCssColorString("#9370DB"));

  /**
   * An immutable Color instance initialized to CSS color #3CB371
   * <span class="colorSwath" style="background: #3CB371;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMSEAGREEN = Object.freeze(Color.fromCssColorString("#3CB371"));

  /**
   * An immutable Color instance initialized to CSS color #7B68EE
   * <span class="colorSwath" style="background: #7B68EE;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMSLATEBLUE = Object.freeze(Color.fromCssColorString("#7B68EE"));

  /**
   * An immutable Color instance initialized to CSS color #00FA9A
   * <span class="colorSwath" style="background: #00FA9A;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMSPRINGGREEN = Object.freeze(Color.fromCssColorString("#00FA9A"));

  /**
   * An immutable Color instance initialized to CSS color #48D1CC
   * <span class="colorSwath" style="background: #48D1CC;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMTURQUOISE = Object.freeze(Color.fromCssColorString("#48D1CC"));

  /**
   * An immutable Color instance initialized to CSS color #C71585
   * <span class="colorSwath" style="background: #C71585;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MEDIUMVIOLETRED = Object.freeze(Color.fromCssColorString("#C71585"));

  /**
   * An immutable Color instance initialized to CSS color #191970
   * <span class="colorSwath" style="background: #191970;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MIDNIGHTBLUE = Object.freeze(Color.fromCssColorString("#191970"));

  /**
   * An immutable Color instance initialized to CSS color #F5FFFA
   * <span class="colorSwath" style="background: #F5FFFA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MINTCREAM = Object.freeze(Color.fromCssColorString("#F5FFFA"));

  /**
   * An immutable Color instance initialized to CSS color #FFE4E1
   * <span class="colorSwath" style="background: #FFE4E1;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MISTYROSE = Object.freeze(Color.fromCssColorString("#FFE4E1"));

  /**
   * An immutable Color instance initialized to CSS color #FFE4B5
   * <span class="colorSwath" style="background: #FFE4B5;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.MOCCASIN = Object.freeze(Color.fromCssColorString("#FFE4B5"));

  /**
   * An immutable Color instance initialized to CSS color #FFDEAD
   * <span class="colorSwath" style="background: #FFDEAD;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.NAVAJOWHITE = Object.freeze(Color.fromCssColorString("#FFDEAD"));

  /**
   * An immutable Color instance initialized to CSS color #000080
   * <span class="colorSwath" style="background: #000080;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.NAVY = Object.freeze(Color.fromCssColorString("#000080"));

  /**
   * An immutable Color instance initialized to CSS color #FDF5E6
   * <span class="colorSwath" style="background: #FDF5E6;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.OLDLACE = Object.freeze(Color.fromCssColorString("#FDF5E6"));

  /**
   * An immutable Color instance initialized to CSS color #808000
   * <span class="colorSwath" style="background: #808000;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.OLIVE = Object.freeze(Color.fromCssColorString("#808000"));

  /**
   * An immutable Color instance initialized to CSS color #6B8E23
   * <span class="colorSwath" style="background: #6B8E23;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.OLIVEDRAB = Object.freeze(Color.fromCssColorString("#6B8E23"));

  /**
   * An immutable Color instance initialized to CSS color #FFA500
   * <span class="colorSwath" style="background: #FFA500;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ORANGE = Object.freeze(Color.fromCssColorString("#FFA500"));

  /**
   * An immutable Color instance initialized to CSS color #FF4500
   * <span class="colorSwath" style="background: #FF4500;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ORANGERED = Object.freeze(Color.fromCssColorString("#FF4500"));

  /**
   * An immutable Color instance initialized to CSS color #DA70D6
   * <span class="colorSwath" style="background: #DA70D6;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ORCHID = Object.freeze(Color.fromCssColorString("#DA70D6"));

  /**
   * An immutable Color instance initialized to CSS color #EEE8AA
   * <span class="colorSwath" style="background: #EEE8AA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PALEGOLDENROD = Object.freeze(Color.fromCssColorString("#EEE8AA"));

  /**
   * An immutable Color instance initialized to CSS color #98FB98
   * <span class="colorSwath" style="background: #98FB98;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PALEGREEN = Object.freeze(Color.fromCssColorString("#98FB98"));

  /**
   * An immutable Color instance initialized to CSS color #AFEEEE
   * <span class="colorSwath" style="background: #AFEEEE;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PALETURQUOISE = Object.freeze(Color.fromCssColorString("#AFEEEE"));

  /**
   * An immutable Color instance initialized to CSS color #DB7093
   * <span class="colorSwath" style="background: #DB7093;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PALEVIOLETRED = Object.freeze(Color.fromCssColorString("#DB7093"));

  /**
   * An immutable Color instance initialized to CSS color #FFEFD5
   * <span class="colorSwath" style="background: #FFEFD5;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PAPAYAWHIP = Object.freeze(Color.fromCssColorString("#FFEFD5"));

  /**
   * An immutable Color instance initialized to CSS color #FFDAB9
   * <span class="colorSwath" style="background: #FFDAB9;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PEACHPUFF = Object.freeze(Color.fromCssColorString("#FFDAB9"));

  /**
   * An immutable Color instance initialized to CSS color #CD853F
   * <span class="colorSwath" style="background: #CD853F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PERU = Object.freeze(Color.fromCssColorString("#CD853F"));

  /**
   * An immutable Color instance initialized to CSS color #FFC0CB
   * <span class="colorSwath" style="background: #FFC0CB;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PINK = Object.freeze(Color.fromCssColorString("#FFC0CB"));

  /**
   * An immutable Color instance initialized to CSS color #DDA0DD
   * <span class="colorSwath" style="background: #DDA0DD;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PLUM = Object.freeze(Color.fromCssColorString("#DDA0DD"));

  /**
   * An immutable Color instance initialized to CSS color #B0E0E6
   * <span class="colorSwath" style="background: #B0E0E6;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.POWDERBLUE = Object.freeze(Color.fromCssColorString("#B0E0E6"));

  /**
   * An immutable Color instance initialized to CSS color #800080
   * <span class="colorSwath" style="background: #800080;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.PURPLE = Object.freeze(Color.fromCssColorString("#800080"));

  /**
   * An immutable Color instance initialized to CSS color #FF0000
   * <span class="colorSwath" style="background: #FF0000;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.RED = Object.freeze(Color.fromCssColorString("#FF0000"));

  /**
   * An immutable Color instance initialized to CSS color #BC8F8F
   * <span class="colorSwath" style="background: #BC8F8F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ROSYBROWN = Object.freeze(Color.fromCssColorString("#BC8F8F"));

  /**
   * An immutable Color instance initialized to CSS color #4169E1
   * <span class="colorSwath" style="background: #4169E1;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.ROYALBLUE = Object.freeze(Color.fromCssColorString("#4169E1"));

  /**
   * An immutable Color instance initialized to CSS color #8B4513
   * <span class="colorSwath" style="background: #8B4513;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SADDLEBROWN = Object.freeze(Color.fromCssColorString("#8B4513"));

  /**
   * An immutable Color instance initialized to CSS color #FA8072
   * <span class="colorSwath" style="background: #FA8072;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SALMON = Object.freeze(Color.fromCssColorString("#FA8072"));

  /**
   * An immutable Color instance initialized to CSS color #F4A460
   * <span class="colorSwath" style="background: #F4A460;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SANDYBROWN = Object.freeze(Color.fromCssColorString("#F4A460"));

  /**
   * An immutable Color instance initialized to CSS color #2E8B57
   * <span class="colorSwath" style="background: #2E8B57;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SEAGREEN = Object.freeze(Color.fromCssColorString("#2E8B57"));

  /**
   * An immutable Color instance initialized to CSS color #FFF5EE
   * <span class="colorSwath" style="background: #FFF5EE;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SEASHELL = Object.freeze(Color.fromCssColorString("#FFF5EE"));

  /**
   * An immutable Color instance initialized to CSS color #A0522D
   * <span class="colorSwath" style="background: #A0522D;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SIENNA = Object.freeze(Color.fromCssColorString("#A0522D"));

  /**
   * An immutable Color instance initialized to CSS color #C0C0C0
   * <span class="colorSwath" style="background: #C0C0C0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SILVER = Object.freeze(Color.fromCssColorString("#C0C0C0"));

  /**
   * An immutable Color instance initialized to CSS color #87CEEB
   * <span class="colorSwath" style="background: #87CEEB;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SKYBLUE = Object.freeze(Color.fromCssColorString("#87CEEB"));

  /**
   * An immutable Color instance initialized to CSS color #6A5ACD
   * <span class="colorSwath" style="background: #6A5ACD;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SLATEBLUE = Object.freeze(Color.fromCssColorString("#6A5ACD"));

  /**
   * An immutable Color instance initialized to CSS color #708090
   * <span class="colorSwath" style="background: #708090;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SLATEGRAY = Object.freeze(Color.fromCssColorString("#708090"));

  /**
   * An immutable Color instance initialized to CSS color #708090
   * <span class="colorSwath" style="background: #708090;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SLATEGREY = Color.SLATEGRAY;

  /**
   * An immutable Color instance initialized to CSS color #FFFAFA
   * <span class="colorSwath" style="background: #FFFAFA;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SNOW = Object.freeze(Color.fromCssColorString("#FFFAFA"));

  /**
   * An immutable Color instance initialized to CSS color #00FF7F
   * <span class="colorSwath" style="background: #00FF7F;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.SPRINGGREEN = Object.freeze(Color.fromCssColorString("#00FF7F"));

  /**
   * An immutable Color instance initialized to CSS color #4682B4
   * <span class="colorSwath" style="background: #4682B4;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.STEELBLUE = Object.freeze(Color.fromCssColorString("#4682B4"));

  /**
   * An immutable Color instance initialized to CSS color #D2B48C
   * <span class="colorSwath" style="background: #D2B48C;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.TAN = Object.freeze(Color.fromCssColorString("#D2B48C"));

  /**
   * An immutable Color instance initialized to CSS color #008080
   * <span class="colorSwath" style="background: #008080;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.TEAL = Object.freeze(Color.fromCssColorString("#008080"));

  /**
   * An immutable Color instance initialized to CSS color #D8BFD8
   * <span class="colorSwath" style="background: #D8BFD8;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.THISTLE = Object.freeze(Color.fromCssColorString("#D8BFD8"));

  /**
   * An immutable Color instance initialized to CSS color #FF6347
   * <span class="colorSwath" style="background: #FF6347;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.TOMATO = Object.freeze(Color.fromCssColorString("#FF6347"));

  /**
   * An immutable Color instance initialized to CSS color #40E0D0
   * <span class="colorSwath" style="background: #40E0D0;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.TURQUOISE = Object.freeze(Color.fromCssColorString("#40E0D0"));

  /**
   * An immutable Color instance initialized to CSS color #EE82EE
   * <span class="colorSwath" style="background: #EE82EE;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.VIOLET = Object.freeze(Color.fromCssColorString("#EE82EE"));

  /**
   * An immutable Color instance initialized to CSS color #F5DEB3
   * <span class="colorSwath" style="background: #F5DEB3;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.WHEAT = Object.freeze(Color.fromCssColorString("#F5DEB3"));

  /**
   * An immutable Color instance initialized to CSS color #FFFFFF
   * <span class="colorSwath" style="background: #FFFFFF;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.WHITE = Object.freeze(Color.fromCssColorString("#FFFFFF"));

  /**
   * An immutable Color instance initialized to CSS color #F5F5F5
   * <span class="colorSwath" style="background: #F5F5F5;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.WHITESMOKE = Object.freeze(Color.fromCssColorString("#F5F5F5"));

  /**
   * An immutable Color instance initialized to CSS color #FFFF00
   * <span class="colorSwath" style="background: #FFFF00;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.YELLOW = Object.freeze(Color.fromCssColorString("#FFFF00"));

  /**
   * An immutable Color instance initialized to CSS color #9ACD32
   * <span class="colorSwath" style="background: #9ACD32;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.YELLOWGREEN = Object.freeze(Color.fromCssColorString("#9ACD32"));

  /**
   * An immutable Color instance initialized to CSS transparent.
   * <span class="colorSwath" style="background: transparent;"></span>
   *
   * @constant
   * @type {Color}
   */
  Color.TRANSPARENT = Object.freeze(new Color(0, 0, 0, 0));

  /**
   * Value and type information for per-instance geometry color.
   *
   * @alias ColorGeometryInstanceAttribute
   * @constructor
   *
   * @param {Number} [red=1.0] The red component.
   * @param {Number} [green=1.0] The green component.
   * @param {Number} [blue=1.0] The blue component.
   * @param {Number} [alpha=1.0] The alpha component.
   *
   *
   * @example
   * var instance = new Cesium.GeometryInstance({
   *   geometry : Cesium.BoxGeometry.fromDimensions({
   *     dimensions : new Cesium.Cartesian3(1000000.0, 1000000.0, 500000.0)
   *   }),
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(0.0, 0.0)), new Cesium.Cartesian3(0.0, 0.0, 1000000.0), new Cesium.Matrix4()),
   *   id : 'box',
   *   attributes : {
   *     color : new Cesium.ColorGeometryInstanceAttribute(red, green, blue, alpha)
   *   }
   * });
   *
   * @see GeometryInstance
   * @see GeometryInstanceAttribute
   */
  function ColorGeometryInstanceAttribute(red, green, blue, alpha) {
    red = defaultValue(red, 1.0);
    green = defaultValue(green, 1.0);
    blue = defaultValue(blue, 1.0);
    alpha = defaultValue(alpha, 1.0);

    /**
     * The values for the attributes stored in a typed array.
     *
     * @type Uint8Array
     *
     * @default [255, 255, 255, 255]
     */
    this.value = new Uint8Array([
      Color.floatToByte(red),
      Color.floatToByte(green),
      Color.floatToByte(blue),
      Color.floatToByte(alpha),
    ]);
  }

  Object.defineProperties(ColorGeometryInstanceAttribute.prototype, {
    /**
     * The datatype of each component in the attribute, e.g., individual elements in
     * {@link ColorGeometryInstanceAttribute#value}.
     *
     * @memberof ColorGeometryInstanceAttribute.prototype
     *
     * @type {ComponentDatatype}
     * @readonly
     *
     * @default {@link ComponentDatatype.UNSIGNED_BYTE}
     */
    componentDatatype: {
      get: function () {
        return ComponentDatatype$1.UNSIGNED_BYTE;
      },
    },

    /**
     * The number of components in the attributes, i.e., {@link ColorGeometryInstanceAttribute#value}.
     *
     * @memberof ColorGeometryInstanceAttribute.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @default 4
     */
    componentsPerAttribute: {
      get: function () {
        return 4;
      },
    },

    /**
     * When <code>true</code> and <code>componentDatatype</code> is an integer format,
     * indicate that the components should be mapped to the range [0, 1] (unsigned)
     * or [-1, 1] (signed) when they are accessed as floating-point for rendering.
     *
     * @memberof ColorGeometryInstanceAttribute.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    normalize: {
      get: function () {
        return true;
      },
    },
  });

  /**
   * Creates a new {@link ColorGeometryInstanceAttribute} instance given the provided {@link Color}.
   *
   * @param {Color} color The color.
   * @returns {ColorGeometryInstanceAttribute} The new {@link ColorGeometryInstanceAttribute} instance.
   *
   * @example
   * var instance = new Cesium.GeometryInstance({
   *   geometry : geometry,
   *   attributes : {
   *     color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.CORNFLOWERBLUE),
   *   }
   * });
   */
  ColorGeometryInstanceAttribute.fromColor = function (color) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(color)) {
      throw new DeveloperError("color is required.");
    }
    //>>includeEnd('debug');

    return new ColorGeometryInstanceAttribute(
      color.red,
      color.green,
      color.blue,
      color.alpha
    );
  };

  /**
   * Converts a color to a typed array that can be used to assign a color attribute.
   *
   * @param {Color} color The color.
   * @param {Uint8Array} [result] The array to store the result in, if undefined a new instance will be created.
   *
   * @returns {Uint8Array} The modified result parameter or a new instance if result was undefined.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA, attributes.color);
   */
  ColorGeometryInstanceAttribute.toValue = function (color, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(color)) {
      throw new DeveloperError("color is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Uint8Array(color.toBytes());
    }
    return color.toBytes(result);
  };

  /**
   * Compares the provided ColorGeometryInstanceAttributes and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {ColorGeometryInstanceAttribute} [left] The first ColorGeometryInstanceAttribute.
   * @param {ColorGeometryInstanceAttribute} [right] The second ColorGeometryInstanceAttribute.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  ColorGeometryInstanceAttribute.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.value[0] === right.value[0] &&
        left.value[1] === right.value[1] &&
        left.value[2] === right.value[2] &&
        left.value[3] === right.value[3])
    );
  };

  /**
   * Describes a compressed texture and contains a compressed texture buffer.
   * @alias CompressedTextureBuffer
   * @constructor
   *
   * @param {PixelFormat} internalFormat The pixel format of the compressed texture.
   * @param {Number} width The width of the texture.
   * @param {Number} height The height of the texture.
   * @param {Uint8Array} buffer The compressed texture buffer.
   */
  function CompressedTextureBuffer(internalFormat, width, height, buffer) {
    this._format = internalFormat;
    this._width = width;
    this._height = height;
    this._buffer = buffer;
  }

  Object.defineProperties(CompressedTextureBuffer.prototype, {
    /**
     * The format of the compressed texture.
     * @type PixelFormat
     * @readonly
     * @memberof CompressedTextureBuffer.prototype
     */
    internalFormat: {
      get: function () {
        return this._format;
      },
    },
    /**
     * The width of the texture.
     * @type Number
     * @readonly
     * @memberof CompressedTextureBuffer.prototype
     */
    width: {
      get: function () {
        return this._width;
      },
    },
    /**
     * The height of the texture.
     * @type Number
     * @readonly
     * @memberof CompressedTextureBuffer.prototype
     */
    height: {
      get: function () {
        return this._height;
      },
    },
    /**
     * The compressed texture buffer.
     * @type Uint8Array
     * @readonly
     * @memberof CompressedTextureBuffer.prototype
     */
    bufferView: {
      get: function () {
        return this._buffer;
      },
    },
  });

  /**
   * Creates a shallow clone of a compressed texture buffer.
   *
   * @param {CompressedTextureBuffer} object The compressed texture buffer to be cloned.
   * @return {CompressedTextureBuffer} A shallow clone of the compressed texture buffer.
   */
  CompressedTextureBuffer.clone = function (object) {
    if (!defined(object)) {
      return undefined;
    }

    return new CompressedTextureBuffer(
      object._format,
      object._width,
      object._height,
      object._buffer
    );
  };

  /**
   * Creates a shallow clone of this compressed texture buffer.
   *
   * @return {CompressedTextureBuffer} A shallow clone of the compressed texture buffer.
   */
  CompressedTextureBuffer.prototype.clone = function () {
    return CompressedTextureBuffer.clone(this);
  };

  var removeDuplicatesEpsilon = CesiumMath.EPSILON10;

  /**
   * Removes adjacent duplicate values in an array of values.
   *
   * @param {Array.<*>} [values] The array of values.
   * @param {Function} equalsEpsilon Function to compare values with an epsilon. Boolean equalsEpsilon(left, right, epsilon).
   * @param {Boolean} [wrapAround=false] Compare the last value in the array against the first value.
   * @returns {Array.<*>|undefined} A new array of values with no adjacent duplicate values or the input array if no duplicates were found.
   *
   * @example
   * // Returns [(1.0, 1.0, 1.0), (2.0, 2.0, 2.0), (3.0, 3.0, 3.0), (1.0, 1.0, 1.0)]
   * var values = [
   *     new Cesium.Cartesian3(1.0, 1.0, 1.0),
   *     new Cesium.Cartesian3(1.0, 1.0, 1.0),
   *     new Cesium.Cartesian3(2.0, 2.0, 2.0),
   *     new Cesium.Cartesian3(3.0, 3.0, 3.0),
   *     new Cesium.Cartesian3(1.0, 1.0, 1.0)];
   * var nonDuplicatevalues = Cesium.PolylinePipeline.removeDuplicates(values, Cartesian3.equalsEpsilon);
   *
   * @example
   * // Returns [(1.0, 1.0, 1.0), (2.0, 2.0, 2.0), (3.0, 3.0, 3.0)]
   * var values = [
   *     new Cesium.Cartesian3(1.0, 1.0, 1.0),
   *     new Cesium.Cartesian3(1.0, 1.0, 1.0),
   *     new Cesium.Cartesian3(2.0, 2.0, 2.0),
   *     new Cesium.Cartesian3(3.0, 3.0, 3.0),
   *     new Cesium.Cartesian3(1.0, 1.0, 1.0)];
   * var nonDuplicatevalues = Cesium.PolylinePipeline.removeDuplicates(values, Cartesian3.equalsEpsilon, true);
   *
   * @private
   */
  function arrayRemoveDuplicates(values, equalsEpsilon, wrapAround) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("equalsEpsilon", equalsEpsilon);
    //>>includeEnd('debug');

    if (!defined(values)) {
      return undefined;
    }

    wrapAround = defaultValue(wrapAround, false);

    var length = values.length;
    if (length < 2) {
      return values;
    }

    var i;
    var v0;
    var v1;

    for (i = 1; i < length; ++i) {
      v0 = values[i - 1];
      v1 = values[i];
      if (equalsEpsilon(v0, v1, removeDuplicatesEpsilon)) {
        break;
      }
    }

    if (i === length) {
      if (
        wrapAround &&
        equalsEpsilon(
          values[0],
          values[values.length - 1],
          removeDuplicatesEpsilon
        )
      ) {
        return values.slice(1);
      }
      return values;
    }

    var cleanedvalues = values.slice(0, i);
    for (; i < length; ++i) {
      // v0 is set by either the previous loop, or the previous clean point.
      v1 = values[i];
      if (!equalsEpsilon(v0, v1, removeDuplicatesEpsilon)) {
        cleanedvalues.push(v1);
        v0 = v1;
      }
    }

    if (
      wrapAround &&
      cleanedvalues.length > 1 &&
      equalsEpsilon(
        cleanedvalues[0],
        cleanedvalues[cleanedvalues.length - 1],
        removeDuplicatesEpsilon
      )
    ) {
      cleanedvalues.shift();
    }

    return cleanedvalues;
  }

  /**
   * @private
   */
  var CoplanarPolygonGeometryLibrary = {};

  var scratchIntersectionPoint = new Cartesian3();
  var scratchXAxis = new Cartesian3();
  var scratchYAxis = new Cartesian3();
  var scratchZAxis = new Cartesian3();
  var obbScratch = new OrientedBoundingBox();

  CoplanarPolygonGeometryLibrary.validOutline = function (positions) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("positions", positions);
    //>>includeEnd('debug');

    var orientedBoundingBox = OrientedBoundingBox.fromPoints(
      positions,
      obbScratch
    );
    var halfAxes = orientedBoundingBox.halfAxes;
    var xAxis = Matrix3.getColumn(halfAxes, 0, scratchXAxis);
    var yAxis = Matrix3.getColumn(halfAxes, 1, scratchYAxis);
    var zAxis = Matrix3.getColumn(halfAxes, 2, scratchZAxis);

    var xMag = Cartesian3.magnitude(xAxis);
    var yMag = Cartesian3.magnitude(yAxis);
    var zMag = Cartesian3.magnitude(zAxis);

    // If all the points are on a line return undefined because we can't draw a polygon
    return !(
      (xMag === 0 && (yMag === 0 || zMag === 0)) ||
      (yMag === 0 && zMag === 0)
    );
  };

  // call after removeDuplicates
  CoplanarPolygonGeometryLibrary.computeProjectTo2DArguments = function (
    positions,
    centerResult,
    planeAxis1Result,
    planeAxis2Result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("positions", positions);
    Check.defined("centerResult", centerResult);
    Check.defined("planeAxis1Result", planeAxis1Result);
    Check.defined("planeAxis2Result", planeAxis2Result);
    //>>includeEnd('debug');

    var orientedBoundingBox = OrientedBoundingBox.fromPoints(
      positions,
      obbScratch
    );
    var halfAxes = orientedBoundingBox.halfAxes;
    var xAxis = Matrix3.getColumn(halfAxes, 0, scratchXAxis);
    var yAxis = Matrix3.getColumn(halfAxes, 1, scratchYAxis);
    var zAxis = Matrix3.getColumn(halfAxes, 2, scratchZAxis);

    var xMag = Cartesian3.magnitude(xAxis);
    var yMag = Cartesian3.magnitude(yAxis);
    var zMag = Cartesian3.magnitude(zAxis);
    var min = Math.min(xMag, yMag, zMag);

    // If all the points are on a line return undefined because we can't draw a polygon
    if (
      (xMag === 0 && (yMag === 0 || zMag === 0)) ||
      (yMag === 0 && zMag === 0)
    ) {
      return false;
    }

    var planeAxis1;
    var planeAxis2;

    if (min === yMag || min === zMag) {
      planeAxis1 = xAxis;
    }
    if (min === xMag) {
      planeAxis1 = yAxis;
    } else if (min === zMag) {
      planeAxis2 = yAxis;
    }
    if (min === xMag || min === yMag) {
      planeAxis2 = zAxis;
    }

    Cartesian3.normalize(planeAxis1, planeAxis1Result);
    Cartesian3.normalize(planeAxis2, planeAxis2Result);
    Cartesian3.clone(orientedBoundingBox.center, centerResult);
    return true;
  };

  function projectTo2D(position, center, axis1, axis2, result) {
    var v = Cartesian3.subtract(position, center, scratchIntersectionPoint);
    var x = Cartesian3.dot(axis1, v);
    var y = Cartesian3.dot(axis2, v);

    return Cartesian2.fromElements(x, y, result);
  }

  CoplanarPolygonGeometryLibrary.createProjectPointsTo2DFunction = function (
    center,
    axis1,
    axis2
  ) {
    return function (positions) {
      var positionResults = new Array(positions.length);
      for (var i = 0; i < positions.length; i++) {
        positionResults[i] = projectTo2D(positions[i], center, axis1, axis2);
      }

      return positionResults;
    };
  };

  CoplanarPolygonGeometryLibrary.createProjectPointTo2DFunction = function (
    center,
    axis1,
    axis2
  ) {
    return function (position, result) {
      return projectTo2D(position, center, axis1, axis2, result);
    };
  };

  function calculateM(ellipticity, major, latitude) {
    if (ellipticity === 0.0) {
      // sphere
      return major * latitude;
    }

    var e2 = ellipticity * ellipticity;
    var e4 = e2 * e2;
    var e6 = e4 * e2;
    var e8 = e6 * e2;
    var e10 = e8 * e2;
    var e12 = e10 * e2;
    var phi = latitude;
    var sin2Phi = Math.sin(2 * phi);
    var sin4Phi = Math.sin(4 * phi);
    var sin6Phi = Math.sin(6 * phi);
    var sin8Phi = Math.sin(8 * phi);
    var sin10Phi = Math.sin(10 * phi);
    var sin12Phi = Math.sin(12 * phi);

    return (
      major *
      ((1 -
        e2 / 4 -
        (3 * e4) / 64 -
        (5 * e6) / 256 -
        (175 * e8) / 16384 -
        (441 * e10) / 65536 -
        (4851 * e12) / 1048576) *
        phi -
        ((3 * e2) / 8 +
          (3 * e4) / 32 +
          (45 * e6) / 1024 +
          (105 * e8) / 4096 +
          (2205 * e10) / 131072 +
          (6237 * e12) / 524288) *
          sin2Phi +
        ((15 * e4) / 256 +
          (45 * e6) / 1024 +
          (525 * e8) / 16384 +
          (1575 * e10) / 65536 +
          (155925 * e12) / 8388608) *
          sin4Phi -
        ((35 * e6) / 3072 +
          (175 * e8) / 12288 +
          (3675 * e10) / 262144 +
          (13475 * e12) / 1048576) *
          sin6Phi +
        ((315 * e8) / 131072 + (2205 * e10) / 524288 + (43659 * e12) / 8388608) *
          sin8Phi -
        ((693 * e10) / 1310720 + (6237 * e12) / 5242880) * sin10Phi +
        ((1001 * e12) / 8388608) * sin12Phi)
    );
  }

  function calculateInverseM(M, ellipticity, major) {
    var d = M / major;

    if (ellipticity === 0.0) {
      // sphere
      return d;
    }

    var d2 = d * d;
    var d3 = d2 * d;
    var d4 = d3 * d;
    var e = ellipticity;
    var e2 = e * e;
    var e4 = e2 * e2;
    var e6 = e4 * e2;
    var e8 = e6 * e2;
    var e10 = e8 * e2;
    var e12 = e10 * e2;
    var sin2D = Math.sin(2 * d);
    var cos2D = Math.cos(2 * d);
    var sin4D = Math.sin(4 * d);
    var cos4D = Math.cos(4 * d);
    var sin6D = Math.sin(6 * d);
    var cos6D = Math.cos(6 * d);
    var sin8D = Math.sin(8 * d);
    var cos8D = Math.cos(8 * d);
    var sin10D = Math.sin(10 * d);
    var cos10D = Math.cos(10 * d);
    var sin12D = Math.sin(12 * d);

    return (
      d +
      (d * e2) / 4 +
      (7 * d * e4) / 64 +
      (15 * d * e6) / 256 +
      (579 * d * e8) / 16384 +
      (1515 * d * e10) / 65536 +
      (16837 * d * e12) / 1048576 +
      ((3 * d * e4) / 16 +
        (45 * d * e6) / 256 -
        (d * (32 * d2 - 561) * e8) / 4096 -
        (d * (232 * d2 - 1677) * e10) / 16384 +
        (d * (399985 - 90560 * d2 + 512 * d4) * e12) / 5242880) *
        cos2D +
      ((21 * d * e6) / 256 +
        (483 * d * e8) / 4096 -
        (d * (224 * d2 - 1969) * e10) / 16384 -
        (d * (33152 * d2 - 112599) * e12) / 1048576) *
        cos4D +
      ((151 * d * e8) / 4096 +
        (4681 * d * e10) / 65536 +
        (1479 * d * e12) / 16384 -
        (453 * d3 * e12) / 32768) *
        cos6D +
      ((1097 * d * e10) / 65536 + (42783 * d * e12) / 1048576) * cos8D +
      ((8011 * d * e12) / 1048576) * cos10D +
      ((3 * e2) / 8 +
        (3 * e4) / 16 +
        (213 * e6) / 2048 -
        (3 * d2 * e6) / 64 +
        (255 * e8) / 4096 -
        (33 * d2 * e8) / 512 +
        (20861 * e10) / 524288 -
        (33 * d2 * e10) / 512 +
        (d4 * e10) / 1024 +
        (28273 * e12) / 1048576 -
        (471 * d2 * e12) / 8192 +
        (9 * d4 * e12) / 4096) *
        sin2D +
      ((21 * e4) / 256 +
        (21 * e6) / 256 +
        (533 * e8) / 8192 -
        (21 * d2 * e8) / 512 +
        (197 * e10) / 4096 -
        (315 * d2 * e10) / 4096 +
        (584039 * e12) / 16777216 -
        (12517 * d2 * e12) / 131072 +
        (7 * d4 * e12) / 2048) *
        sin4D +
      ((151 * e6) / 6144 +
        (151 * e8) / 4096 +
        (5019 * e10) / 131072 -
        (453 * d2 * e10) / 16384 +
        (26965 * e12) / 786432 -
        (8607 * d2 * e12) / 131072) *
        sin6D +
      ((1097 * e8) / 131072 +
        (1097 * e10) / 65536 +
        (225797 * e12) / 10485760 -
        (1097 * d2 * e12) / 65536) *
        sin8D +
      ((8011 * e10) / 2621440 + (8011 * e12) / 1048576) * sin10D +
      ((293393 * e12) / 251658240) * sin12D
    );
  }

  function calculateSigma(ellipticity, latitude) {
    if (ellipticity === 0.0) {
      // sphere
      return Math.log(Math.tan(0.5 * (CesiumMath.PI_OVER_TWO + latitude)));
    }

    var eSinL = ellipticity * Math.sin(latitude);
    return (
      Math.log(Math.tan(0.5 * (CesiumMath.PI_OVER_TWO + latitude))) -
      (ellipticity / 2.0) * Math.log((1 + eSinL) / (1 - eSinL))
    );
  }

  function calculateHeading(
    ellipsoidRhumbLine,
    firstLongitude,
    firstLatitude,
    secondLongitude,
    secondLatitude
  ) {
    var sigma1 = calculateSigma(ellipsoidRhumbLine._ellipticity, firstLatitude);
    var sigma2 = calculateSigma(ellipsoidRhumbLine._ellipticity, secondLatitude);
    return Math.atan2(
      CesiumMath.negativePiToPi(secondLongitude - firstLongitude),
      sigma2 - sigma1
    );
  }

  function calculateArcLength(
    ellipsoidRhumbLine,
    major,
    minor,
    firstLongitude,
    firstLatitude,
    secondLongitude,
    secondLatitude
  ) {
    var heading = ellipsoidRhumbLine._heading;
    var deltaLongitude = secondLongitude - firstLongitude;

    var distance = 0.0;

    //Check to see if the rhumb line has constant latitude
    //This equation will diverge if heading gets close to 90 degrees
    if (
      CesiumMath.equalsEpsilon(
        Math.abs(heading),
        CesiumMath.PI_OVER_TWO,
        CesiumMath.EPSILON8
      )
    ) {
      //If heading is close to 90 degrees
      if (major === minor) {
        distance =
          major *
          Math.cos(firstLatitude) *
          CesiumMath.negativePiToPi(deltaLongitude);
      } else {
        var sinPhi = Math.sin(firstLatitude);
        distance =
          (major *
            Math.cos(firstLatitude) *
            CesiumMath.negativePiToPi(deltaLongitude)) /
          Math.sqrt(1 - ellipsoidRhumbLine._ellipticitySquared * sinPhi * sinPhi);
      }
    } else {
      var M1 = calculateM(ellipsoidRhumbLine._ellipticity, major, firstLatitude);
      var M2 = calculateM(ellipsoidRhumbLine._ellipticity, major, secondLatitude);

      distance = (M2 - M1) / Math.cos(heading);
    }
    return Math.abs(distance);
  }

  var scratchCart1 = new Cartesian3();
  var scratchCart2 = new Cartesian3();

  function computeProperties(ellipsoidRhumbLine, start, end, ellipsoid) {
    var firstCartesian = Cartesian3.normalize(
      ellipsoid.cartographicToCartesian(start, scratchCart2),
      scratchCart1
    );
    var lastCartesian = Cartesian3.normalize(
      ellipsoid.cartographicToCartesian(end, scratchCart2),
      scratchCart2
    );

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals(
      "value",
      Math.abs(
        Math.abs(Cartesian3.angleBetween(firstCartesian, lastCartesian)) - Math.PI
      ),
      0.0125
    );
    //>>includeEnd('debug');

    var major = ellipsoid.maximumRadius;
    var minor = ellipsoid.minimumRadius;
    var majorSquared = major * major;
    var minorSquared = minor * minor;
    ellipsoidRhumbLine._ellipticitySquared =
      (majorSquared - minorSquared) / majorSquared;
    ellipsoidRhumbLine._ellipticity = Math.sqrt(
      ellipsoidRhumbLine._ellipticitySquared
    );

    ellipsoidRhumbLine._start = Cartographic.clone(
      start,
      ellipsoidRhumbLine._start
    );
    ellipsoidRhumbLine._start.height = 0;

    ellipsoidRhumbLine._end = Cartographic.clone(end, ellipsoidRhumbLine._end);
    ellipsoidRhumbLine._end.height = 0;

    ellipsoidRhumbLine._heading = calculateHeading(
      ellipsoidRhumbLine,
      start.longitude,
      start.latitude,
      end.longitude,
      end.latitude
    );
    ellipsoidRhumbLine._distance = calculateArcLength(
      ellipsoidRhumbLine,
      ellipsoid.maximumRadius,
      ellipsoid.minimumRadius,
      start.longitude,
      start.latitude,
      end.longitude,
      end.latitude
    );
  }

  function interpolateUsingSurfaceDistance(
    start,
    heading,
    distance,
    major,
    ellipticity,
    result
  ) {
    var ellipticitySquared = ellipticity * ellipticity;

    var longitude;
    var latitude;
    var deltaLongitude;

    //Check to see if the rhumb line has constant latitude
    //This won't converge if heading is close to 90 degrees
    if (
      Math.abs(CesiumMath.PI_OVER_TWO - Math.abs(heading)) > CesiumMath.EPSILON8
    ) {
      //Calculate latitude of the second point
      var M1 = calculateM(ellipticity, major, start.latitude);
      var deltaM = distance * Math.cos(heading);
      var M2 = M1 + deltaM;
      latitude = calculateInverseM(M2, ellipticity, major);

      //Now find the longitude of the second point
      var sigma1 = calculateSigma(ellipticity, start.latitude);
      var sigma2 = calculateSigma(ellipticity, latitude);
      deltaLongitude = Math.tan(heading) * (sigma2 - sigma1);
      longitude = CesiumMath.negativePiToPi(start.longitude + deltaLongitude);
    } else {
      //If heading is close to 90 degrees
      latitude = start.latitude;
      var localRad;

      if (ellipticity === 0.0) {
        // sphere
        localRad = major * Math.cos(start.latitude);
      } else {
        var sinPhi = Math.sin(start.latitude);
        localRad =
          (major * Math.cos(start.latitude)) /
          Math.sqrt(1 - ellipticitySquared * sinPhi * sinPhi);
      }

      deltaLongitude = distance / localRad;
      if (heading > 0.0) {
        longitude = CesiumMath.negativePiToPi(start.longitude + deltaLongitude);
      } else {
        longitude = CesiumMath.negativePiToPi(start.longitude - deltaLongitude);
      }
    }

    if (defined(result)) {
      result.longitude = longitude;
      result.latitude = latitude;
      result.height = 0;

      return result;
    }

    return new Cartographic(longitude, latitude, 0);
  }

  /**
   * Initializes a rhumb line on the ellipsoid connecting the two provided planetodetic points.
   *
   * @alias EllipsoidRhumbLine
   * @constructor
   *
   * @param {Cartographic} [start] The initial planetodetic point on the path.
   * @param {Cartographic} [end] The final planetodetic point on the path.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the rhumb line lies.
   *
   * @exception {DeveloperError} angle between start and end must be at least 0.0125 radians.
   */
  function EllipsoidRhumbLine(start, end, ellipsoid) {
    var e = defaultValue(ellipsoid, Ellipsoid.WGS84);
    this._ellipsoid = e;
    this._start = new Cartographic();
    this._end = new Cartographic();

    this._heading = undefined;
    this._distance = undefined;
    this._ellipticity = undefined;
    this._ellipticitySquared = undefined;

    if (defined(start) && defined(end)) {
      computeProperties(this, start, end, e);
    }
  }

  Object.defineProperties(EllipsoidRhumbLine.prototype, {
    /**
     * Gets the ellipsoid.
     * @memberof EllipsoidRhumbLine.prototype
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },

    /**
     * Gets the surface distance between the start and end point
     * @memberof EllipsoidRhumbLine.prototype
     * @type {Number}
     * @readonly
     */
    surfaceDistance: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("distance", this._distance);
        //>>includeEnd('debug');

        return this._distance;
      },
    },

    /**
     * Gets the initial planetodetic point on the path.
     * @memberof EllipsoidRhumbLine.prototype
     * @type {Cartographic}
     * @readonly
     */
    start: {
      get: function () {
        return this._start;
      },
    },

    /**
     * Gets the final planetodetic point on the path.
     * @memberof EllipsoidRhumbLine.prototype
     * @type {Cartographic}
     * @readonly
     */
    end: {
      get: function () {
        return this._end;
      },
    },

    /**
     * Gets the heading from the start point to the end point.
     * @memberof EllipsoidRhumbLine.prototype
     * @type {Number}
     * @readonly
     */
    heading: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("distance", this._distance);
        //>>includeEnd('debug');

        return this._heading;
      },
    },
  });

  /**
   * Create a rhumb line using an initial position with a heading and distance.
   *
   * @param {Cartographic} start The initial planetodetic point on the path.
   * @param {Number} heading The heading in radians.
   * @param {Number} distance The rhumb line distance between the start and end point.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the rhumb line lies.
   * @param {EllipsoidRhumbLine} [result] The object in which to store the result.
   * @returns {EllipsoidRhumbLine} The EllipsoidRhumbLine object.
   */
  EllipsoidRhumbLine.fromStartHeadingDistance = function (
    start,
    heading,
    distance,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("start", start);
    Check.defined("heading", heading);
    Check.defined("distance", distance);
    Check.typeOf.number.greaterThan("distance", distance, 0.0);
    //>>includeEnd('debug');

    var e = defaultValue(ellipsoid, Ellipsoid.WGS84);
    var major = e.maximumRadius;
    var minor = e.minimumRadius;
    var majorSquared = major * major;
    var minorSquared = minor * minor;
    var ellipticity = Math.sqrt((majorSquared - minorSquared) / majorSquared);

    heading = CesiumMath.negativePiToPi(heading);
    var end = interpolateUsingSurfaceDistance(
      start,
      heading,
      distance,
      e.maximumRadius,
      ellipticity
    );

    if (
      !defined(result) ||
      (defined(ellipsoid) && !ellipsoid.equals(result.ellipsoid))
    ) {
      return new EllipsoidRhumbLine(start, end, e);
    }

    result.setEndPoints(start, end);
    return result;
  };

  /**
   * Sets the start and end points of the rhumb line.
   *
   * @param {Cartographic} start The initial planetodetic point on the path.
   * @param {Cartographic} end The final planetodetic point on the path.
   */
  EllipsoidRhumbLine.prototype.setEndPoints = function (start, end) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("start", start);
    Check.defined("end", end);
    //>>includeEnd('debug');

    computeProperties(this, start, end, this._ellipsoid);
  };

  /**
   * Provides the location of a point at the indicated portion along the rhumb line.
   *
   * @param {Number} fraction The portion of the distance between the initial and final points.
   * @param {Cartographic} [result] The object in which to store the result.
   * @returns {Cartographic} The location of the point along the rhumb line.
   */
  EllipsoidRhumbLine.prototype.interpolateUsingFraction = function (
    fraction,
    result
  ) {
    return this.interpolateUsingSurfaceDistance(
      fraction * this._distance,
      result
    );
  };

  /**
   * Provides the location of a point at the indicated distance along the rhumb line.
   *
   * @param {Number} distance The distance from the inital point to the point of interest along the rhumbLine.
   * @param {Cartographic} [result] The object in which to store the result.
   * @returns {Cartographic} The location of the point along the rhumb line.
   *
   * @exception {DeveloperError} start and end must be set before calling function interpolateUsingSurfaceDistance
   */
  EllipsoidRhumbLine.prototype.interpolateUsingSurfaceDistance = function (
    distance,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("distance", distance);
    if (!defined(this._distance) || this._distance === 0.0) {
      throw new DeveloperError(
        "EllipsoidRhumbLine must have distinct start and end set."
      );
    }
    //>>includeEnd('debug');

    return interpolateUsingSurfaceDistance(
      this._start,
      this._heading,
      distance,
      this._ellipsoid.maximumRadius,
      this._ellipticity,
      result
    );
  };

  /**
   * Provides the location of a point at the indicated longitude along the rhumb line.
   * If the longitude is outside the range of start and end points, the first intersection with the longitude from the start point in the direction of the heading is returned. This follows the spiral property of a rhumb line.
   *
   * @param {Number} intersectionLongitude The longitude, in radians, at which to find the intersection point from the starting point using the heading.
   * @param {Cartographic} [result] The object in which to store the result.
   * @returns {Cartographic} The location of the intersection point along the rhumb line, undefined if there is no intersection or infinite intersections.
   *
   * @exception {DeveloperError} start and end must be set before calling function findIntersectionWithLongitude.
   */
  EllipsoidRhumbLine.prototype.findIntersectionWithLongitude = function (
    intersectionLongitude,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("intersectionLongitude", intersectionLongitude);
    if (!defined(this._distance) || this._distance === 0.0) {
      throw new DeveloperError(
        "EllipsoidRhumbLine must have distinct start and end set."
      );
    }
    //>>includeEnd('debug');

    var ellipticity = this._ellipticity;
    var heading = this._heading;
    var absHeading = Math.abs(heading);
    var start = this._start;

    intersectionLongitude = CesiumMath.negativePiToPi(intersectionLongitude);

    if (
      CesiumMath.equalsEpsilon(
        Math.abs(intersectionLongitude),
        Math.PI,
        CesiumMath.EPSILON14
      )
    ) {
      intersectionLongitude = CesiumMath.sign(start.longitude) * Math.PI;
    }

    if (!defined(result)) {
      result = new Cartographic();
    }

    // If heading is -PI/2 or PI/2, this is an E-W rhumb line
    // If heading is 0 or PI, this is an N-S rhumb line
    if (Math.abs(CesiumMath.PI_OVER_TWO - absHeading) <= CesiumMath.EPSILON8) {
      result.longitude = intersectionLongitude;
      result.latitude = start.latitude;
      result.height = 0;
      return result;
    } else if (
      CesiumMath.equalsEpsilon(
        Math.abs(CesiumMath.PI_OVER_TWO - absHeading),
        CesiumMath.PI_OVER_TWO,
        CesiumMath.EPSILON8
      )
    ) {
      if (
        CesiumMath.equalsEpsilon(
          intersectionLongitude,
          start.longitude,
          CesiumMath.EPSILON12
        )
      ) {
        return undefined;
      }

      result.longitude = intersectionLongitude;
      result.latitude =
        CesiumMath.PI_OVER_TWO *
        CesiumMath.sign(CesiumMath.PI_OVER_TWO - heading);
      result.height = 0;
      return result;
    }

    // Use iterative solver from Equation 9 from http://edwilliams.org/ellipsoid/ellipsoid.pdf
    var phi1 = start.latitude;
    var eSinPhi1 = ellipticity * Math.sin(phi1);
    var leftComponent =
      Math.tan(0.5 * (CesiumMath.PI_OVER_TWO + phi1)) *
      Math.exp((intersectionLongitude - start.longitude) / Math.tan(heading));
    var denominator = (1 + eSinPhi1) / (1 - eSinPhi1);

    var newPhi = start.latitude;
    var phi;
    do {
      phi = newPhi;
      var eSinPhi = ellipticity * Math.sin(phi);
      var numerator = (1 + eSinPhi) / (1 - eSinPhi);
      newPhi =
        2 *
          Math.atan(
            leftComponent * Math.pow(numerator / denominator, ellipticity / 2)
          ) -
        CesiumMath.PI_OVER_TWO;
    } while (!CesiumMath.equalsEpsilon(newPhi, phi, CesiumMath.EPSILON12));

    result.longitude = intersectionLongitude;
    result.latitude = newPhi;
    result.height = 0;
    return result;
  };

  /**
   * Provides the location of a point at the indicated latitude along the rhumb line.
   * If the latitude is outside the range of start and end points, the first intersection with the latitude from that start point in the direction of the heading is returned. This follows the spiral property of a rhumb line.
   *
   * @param {Number} intersectionLatitude The latitude, in radians, at which to find the intersection point from the starting point using the heading.
   * @param {Cartographic} [result] The object in which to store the result.
   * @returns {Cartographic} The location of the intersection point along the rhumb line, undefined if there is no intersection or infinite intersections.
   *
   * @exception {DeveloperError} start and end must be set before calling function findIntersectionWithLongitude.
   */
  EllipsoidRhumbLine.prototype.findIntersectionWithLatitude = function (
    intersectionLatitude,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("intersectionLatitude", intersectionLatitude);
    if (!defined(this._distance) || this._distance === 0.0) {
      throw new DeveloperError(
        "EllipsoidRhumbLine must have distinct start and end set."
      );
    }
    //>>includeEnd('debug');

    var ellipticity = this._ellipticity;
    var heading = this._heading;
    var start = this._start;

    // If start and end have same latitude, return undefined since it's either no intersection or infinite intersections
    if (
      CesiumMath.equalsEpsilon(
        Math.abs(heading),
        CesiumMath.PI_OVER_TWO,
        CesiumMath.EPSILON8
      )
    ) {
      return;
    }

    // Can be solved using the same equations from interpolateUsingSurfaceDistance
    var sigma1 = calculateSigma(ellipticity, start.latitude);
    var sigma2 = calculateSigma(ellipticity, intersectionLatitude);
    var deltaLongitude = Math.tan(heading) * (sigma2 - sigma1);
    var longitude = CesiumMath.negativePiToPi(start.longitude + deltaLongitude);

    if (defined(result)) {
      result.longitude = longitude;
      result.latitude = intersectionLatitude;
      result.height = 0;

      return result;
    }

    return new Cartographic(longitude, intersectionLatitude, 0);
  };

  function earcut(data, holeIndices, dim) {

      dim = dim || 2;

      var hasHoles = holeIndices && holeIndices.length,
          outerLen = hasHoles ? holeIndices[0] * dim : data.length,
          outerNode = linkedList(data, 0, outerLen, dim, true),
          triangles = [];

      if (!outerNode || outerNode.next === outerNode.prev) return triangles;

      var minX, minY, maxX, maxY, x, y, invSize;

      if (hasHoles) outerNode = eliminateHoles(data, holeIndices, outerNode, dim);

      // if the shape is not too simple, we'll use z-order curve hash later; calculate polygon bbox
      if (data.length > 80 * dim) {
          minX = maxX = data[0];
          minY = maxY = data[1];

          for (var i = dim; i < outerLen; i += dim) {
              x = data[i];
              y = data[i + 1];
              if (x < minX) minX = x;
              if (y < minY) minY = y;
              if (x > maxX) maxX = x;
              if (y > maxY) maxY = y;
          }

          // minX, minY and invSize are later used to transform coords into integers for z-order calculation
          invSize = Math.max(maxX - minX, maxY - minY);
          invSize = invSize !== 0 ? 1 / invSize : 0;
      }

      earcutLinked(outerNode, triangles, dim, minX, minY, invSize);

      return triangles;
  }

  // create a circular doubly linked list from polygon points in the specified winding order
  function linkedList(data, start, end, dim, clockwise) {
      var i, last;

      if (clockwise === (signedArea(data, start, end, dim) > 0)) {
          for (i = start; i < end; i += dim) last = insertNode(i, data[i], data[i + 1], last);
      } else {
          for (i = end - dim; i >= start; i -= dim) last = insertNode(i, data[i], data[i + 1], last);
      }

      if (last && equals(last, last.next)) {
          removeNode(last);
          last = last.next;
      }

      return last;
  }

  // eliminate colinear or duplicate points
  function filterPoints(start, end) {
      if (!start) return start;
      if (!end) end = start;

      var p = start,
          again;
      do {
          again = false;

          if (!p.steiner && (equals(p, p.next) || area(p.prev, p, p.next) === 0)) {
              removeNode(p);
              p = end = p.prev;
              if (p === p.next) break;
              again = true;

          } else {
              p = p.next;
          }
      } while (again || p !== end);

      return end;
  }

  // main ear slicing loop which triangulates a polygon (given as a linked list)
  function earcutLinked(ear, triangles, dim, minX, minY, invSize, pass) {
      if (!ear) return;

      // interlink polygon nodes in z-order
      if (!pass && invSize) indexCurve(ear, minX, minY, invSize);

      var stop = ear,
          prev, next;

      // iterate through ears, slicing them one by one
      while (ear.prev !== ear.next) {
          prev = ear.prev;
          next = ear.next;

          if (invSize ? isEarHashed(ear, minX, minY, invSize) : isEar(ear)) {
              // cut off the triangle
              triangles.push(prev.i / dim);
              triangles.push(ear.i / dim);
              triangles.push(next.i / dim);

              removeNode(ear);

              // skipping the next vertex leads to less sliver triangles
              ear = next.next;
              stop = next.next;

              continue;
          }

          ear = next;

          // if we looped through the whole remaining polygon and can't find any more ears
          if (ear === stop) {
              // try filtering points and slicing again
              if (!pass) {
                  earcutLinked(filterPoints(ear), triangles, dim, minX, minY, invSize, 1);

              // if this didn't work, try curing all small self-intersections locally
              } else if (pass === 1) {
                  ear = cureLocalIntersections(filterPoints(ear), triangles, dim);
                  earcutLinked(ear, triangles, dim, minX, minY, invSize, 2);

              // as a last resort, try splitting the remaining polygon into two
              } else if (pass === 2) {
                  splitEarcut(ear, triangles, dim, minX, minY, invSize);
              }

              break;
          }
      }
  }

  // check whether a polygon node forms a valid ear with adjacent nodes
  function isEar(ear) {
      var a = ear.prev,
          b = ear,
          c = ear.next;

      if (area(a, b, c) >= 0) return false; // reflex, can't be an ear

      // now make sure we don't have other points inside the potential ear
      var p = ear.next.next;

      while (p !== ear.prev) {
          if (pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
              area(p.prev, p, p.next) >= 0) return false;
          p = p.next;
      }

      return true;
  }

  function isEarHashed(ear, minX, minY, invSize) {
      var a = ear.prev,
          b = ear,
          c = ear.next;

      if (area(a, b, c) >= 0) return false; // reflex, can't be an ear

      // triangle bbox; min & max are calculated like this for speed
      var minTX = a.x < b.x ? (a.x < c.x ? a.x : c.x) : (b.x < c.x ? b.x : c.x),
          minTY = a.y < b.y ? (a.y < c.y ? a.y : c.y) : (b.y < c.y ? b.y : c.y),
          maxTX = a.x > b.x ? (a.x > c.x ? a.x : c.x) : (b.x > c.x ? b.x : c.x),
          maxTY = a.y > b.y ? (a.y > c.y ? a.y : c.y) : (b.y > c.y ? b.y : c.y);

      // z-order range for the current triangle bbox;
      var minZ = zOrder(minTX, minTY, minX, minY, invSize),
          maxZ = zOrder(maxTX, maxTY, minX, minY, invSize);

      var p = ear.prevZ,
          n = ear.nextZ;

      // look for points inside the triangle in both directions
      while (p && p.z >= minZ && n && n.z <= maxZ) {
          if (p !== ear.prev && p !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
              area(p.prev, p, p.next) >= 0) return false;
          p = p.prevZ;

          if (n !== ear.prev && n !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
              area(n.prev, n, n.next) >= 0) return false;
          n = n.nextZ;
      }

      // look for remaining points in decreasing z-order
      while (p && p.z >= minZ) {
          if (p !== ear.prev && p !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
              area(p.prev, p, p.next) >= 0) return false;
          p = p.prevZ;
      }

      // look for remaining points in increasing z-order
      while (n && n.z <= maxZ) {
          if (n !== ear.prev && n !== ear.next &&
              pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
              area(n.prev, n, n.next) >= 0) return false;
          n = n.nextZ;
      }

      return true;
  }

  // go through all polygon nodes and cure small local self-intersections
  function cureLocalIntersections(start, triangles, dim) {
      var p = start;
      do {
          var a = p.prev,
              b = p.next.next;

          if (!equals(a, b) && intersects(a, p, p.next, b) && locallyInside(a, b) && locallyInside(b, a)) {

              triangles.push(a.i / dim);
              triangles.push(p.i / dim);
              triangles.push(b.i / dim);

              // remove two nodes involved
              removeNode(p);
              removeNode(p.next);

              p = start = b;
          }
          p = p.next;
      } while (p !== start);

      return filterPoints(p);
  }

  // try splitting polygon into two and triangulate them independently
  function splitEarcut(start, triangles, dim, minX, minY, invSize) {
      // look for a valid diagonal that divides the polygon into two
      var a = start;
      do {
          var b = a.next.next;
          while (b !== a.prev) {
              if (a.i !== b.i && isValidDiagonal(a, b)) {
                  // split the polygon in two by the diagonal
                  var c = splitPolygon(a, b);

                  // filter colinear points around the cuts
                  a = filterPoints(a, a.next);
                  c = filterPoints(c, c.next);

                  // run earcut on each half
                  earcutLinked(a, triangles, dim, minX, minY, invSize);
                  earcutLinked(c, triangles, dim, minX, minY, invSize);
                  return;
              }
              b = b.next;
          }
          a = a.next;
      } while (a !== start);
  }

  // link every hole into the outer loop, producing a single-ring polygon without holes
  function eliminateHoles(data, holeIndices, outerNode, dim) {
      var queue = [],
          i, len, start, end, list;

      for (i = 0, len = holeIndices.length; i < len; i++) {
          start = holeIndices[i] * dim;
          end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
          list = linkedList(data, start, end, dim, false);
          if (list === list.next) list.steiner = true;
          queue.push(getLeftmost(list));
      }

      queue.sort(compareX);

      // process holes from left to right
      for (i = 0; i < queue.length; i++) {
          eliminateHole(queue[i], outerNode);
          outerNode = filterPoints(outerNode, outerNode.next);
      }

      return outerNode;
  }

  function compareX(a, b) {
      return a.x - b.x;
  }

  // find a bridge between vertices that connects hole with an outer ring and and link it
  function eliminateHole(hole, outerNode) {
      outerNode = findHoleBridge(hole, outerNode);
      if (outerNode) {
          var b = splitPolygon(outerNode, hole);
          filterPoints(b, b.next);
      }
  }

  // David Eberly's algorithm for finding a bridge between hole and outer polygon
  function findHoleBridge(hole, outerNode) {
      var p = outerNode,
          hx = hole.x,
          hy = hole.y,
          qx = -Infinity,
          m;

      // find a segment intersected by a ray from the hole's leftmost point to the left;
      // segment's endpoint with lesser x will be potential connection point
      do {
          if (hy <= p.y && hy >= p.next.y && p.next.y !== p.y) {
              var x = p.x + (hy - p.y) * (p.next.x - p.x) / (p.next.y - p.y);
              if (x <= hx && x > qx) {
                  qx = x;
                  if (x === hx) {
                      if (hy === p.y) return p;
                      if (hy === p.next.y) return p.next;
                  }
                  m = p.x < p.next.x ? p : p.next;
              }
          }
          p = p.next;
      } while (p !== outerNode);

      if (!m) return null;

      if (hx === qx) return m; // hole touches outer segment; pick leftmost endpoint

      // look for points inside the triangle of hole point, segment intersection and endpoint;
      // if there are no points found, we have a valid connection;
      // otherwise choose the point of the minimum angle with the ray as connection point

      var stop = m,
          mx = m.x,
          my = m.y,
          tanMin = Infinity,
          tan;

      p = m;

      do {
          if (hx >= p.x && p.x >= mx && hx !== p.x &&
                  pointInTriangle(hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy, p.x, p.y)) {

              tan = Math.abs(hy - p.y) / (hx - p.x); // tangential

              if (locallyInside(p, hole) &&
                  (tan < tanMin || (tan === tanMin && (p.x > m.x || (p.x === m.x && sectorContainsSector(m, p)))))) {
                  m = p;
                  tanMin = tan;
              }
          }

          p = p.next;
      } while (p !== stop);

      return m;
  }

  // whether sector in vertex m contains sector in vertex p in the same coordinates
  function sectorContainsSector(m, p) {
      return area(m.prev, m, p.prev) < 0 && area(p.next, m, m.next) < 0;
  }

  // interlink polygon nodes in z-order
  function indexCurve(start, minX, minY, invSize) {
      var p = start;
      do {
          if (p.z === null) p.z = zOrder(p.x, p.y, minX, minY, invSize);
          p.prevZ = p.prev;
          p.nextZ = p.next;
          p = p.next;
      } while (p !== start);

      p.prevZ.nextZ = null;
      p.prevZ = null;

      sortLinked(p);
  }

  // Simon Tatham's linked list merge sort algorithm
  // http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html
  function sortLinked(list) {
      var i, p, q, e, tail, numMerges, pSize, qSize,
          inSize = 1;

      do {
          p = list;
          list = null;
          tail = null;
          numMerges = 0;

          while (p) {
              numMerges++;
              q = p;
              pSize = 0;
              for (i = 0; i < inSize; i++) {
                  pSize++;
                  q = q.nextZ;
                  if (!q) break;
              }
              qSize = inSize;

              while (pSize > 0 || (qSize > 0 && q)) {

                  if (pSize !== 0 && (qSize === 0 || !q || p.z <= q.z)) {
                      e = p;
                      p = p.nextZ;
                      pSize--;
                  } else {
                      e = q;
                      q = q.nextZ;
                      qSize--;
                  }

                  if (tail) tail.nextZ = e;
                  else list = e;

                  e.prevZ = tail;
                  tail = e;
              }

              p = q;
          }

          tail.nextZ = null;
          inSize *= 2;

      } while (numMerges > 1);

      return list;
  }

  // z-order of a point given coords and inverse of the longer side of data bbox
  function zOrder(x, y, minX, minY, invSize) {
      // coords are transformed into non-negative 15-bit integer range
      x = 32767 * (x - minX) * invSize;
      y = 32767 * (y - minY) * invSize;

      x = (x | (x << 8)) & 0x00FF00FF;
      x = (x | (x << 4)) & 0x0F0F0F0F;
      x = (x | (x << 2)) & 0x33333333;
      x = (x | (x << 1)) & 0x55555555;

      y = (y | (y << 8)) & 0x00FF00FF;
      y = (y | (y << 4)) & 0x0F0F0F0F;
      y = (y | (y << 2)) & 0x33333333;
      y = (y | (y << 1)) & 0x55555555;

      return x | (y << 1);
  }

  // find the leftmost node of a polygon ring
  function getLeftmost(start) {
      var p = start,
          leftmost = start;
      do {
          if (p.x < leftmost.x || (p.x === leftmost.x && p.y < leftmost.y)) leftmost = p;
          p = p.next;
      } while (p !== start);

      return leftmost;
  }

  // check if a point lies within a convex triangle
  function pointInTriangle(ax, ay, bx, by, cx, cy, px, py) {
      return (cx - px) * (ay - py) - (ax - px) * (cy - py) >= 0 &&
             (ax - px) * (by - py) - (bx - px) * (ay - py) >= 0 &&
             (bx - px) * (cy - py) - (cx - px) * (by - py) >= 0;
  }

  // check if a diagonal between two polygon nodes is valid (lies in polygon interior)
  function isValidDiagonal(a, b) {
      return a.next.i !== b.i && a.prev.i !== b.i && !intersectsPolygon(a, b) && // dones't intersect other edges
             (locallyInside(a, b) && locallyInside(b, a) && middleInside(a, b) && // locally visible
              (area(a.prev, a, b.prev) || area(a, b.prev, b)) || // does not create opposite-facing sectors
              equals(a, b) && area(a.prev, a, a.next) > 0 && area(b.prev, b, b.next) > 0); // special zero-length case
  }

  // signed area of a triangle
  function area(p, q, r) {
      return (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
  }

  // check if two points are equal
  function equals(p1, p2) {
      return p1.x === p2.x && p1.y === p2.y;
  }

  // check if two segments intersect
  function intersects(p1, q1, p2, q2) {
      var o1 = sign(area(p1, q1, p2));
      var o2 = sign(area(p1, q1, q2));
      var o3 = sign(area(p2, q2, p1));
      var o4 = sign(area(p2, q2, q1));

      if (o1 !== o2 && o3 !== o4) return true; // general case

      if (o1 === 0 && onSegment(p1, p2, q1)) return true; // p1, q1 and p2 are collinear and p2 lies on p1q1
      if (o2 === 0 && onSegment(p1, q2, q1)) return true; // p1, q1 and q2 are collinear and q2 lies on p1q1
      if (o3 === 0 && onSegment(p2, p1, q2)) return true; // p2, q2 and p1 are collinear and p1 lies on p2q2
      if (o4 === 0 && onSegment(p2, q1, q2)) return true; // p2, q2 and q1 are collinear and q1 lies on p2q2

      return false;
  }

  // for collinear points p, q, r, check if point q lies on segment pr
  function onSegment(p, q, r) {
      return q.x <= Math.max(p.x, r.x) && q.x >= Math.min(p.x, r.x) && q.y <= Math.max(p.y, r.y) && q.y >= Math.min(p.y, r.y);
  }

  function sign(num) {
      return num > 0 ? 1 : num < 0 ? -1 : 0;
  }

  // check if a polygon diagonal intersects any polygon segments
  function intersectsPolygon(a, b) {
      var p = a;
      do {
          if (p.i !== a.i && p.next.i !== a.i && p.i !== b.i && p.next.i !== b.i &&
                  intersects(p, p.next, a, b)) return true;
          p = p.next;
      } while (p !== a);

      return false;
  }

  // check if a polygon diagonal is locally inside the polygon
  function locallyInside(a, b) {
      return area(a.prev, a, a.next) < 0 ?
          area(a, b, a.next) >= 0 && area(a, a.prev, b) >= 0 :
          area(a, b, a.prev) < 0 || area(a, a.next, b) < 0;
  }

  // check if the middle point of a polygon diagonal is inside the polygon
  function middleInside(a, b) {
      var p = a,
          inside = false,
          px = (a.x + b.x) / 2,
          py = (a.y + b.y) / 2;
      do {
          if (((p.y > py) !== (p.next.y > py)) && p.next.y !== p.y &&
                  (px < (p.next.x - p.x) * (py - p.y) / (p.next.y - p.y) + p.x))
              inside = !inside;
          p = p.next;
      } while (p !== a);

      return inside;
  }

  // link two polygon vertices with a bridge; if the vertices belong to the same ring, it splits polygon into two;
  // if one belongs to the outer ring and another to a hole, it merges it into a single ring
  function splitPolygon(a, b) {
      var a2 = new Node$1(a.i, a.x, a.y),
          b2 = new Node$1(b.i, b.x, b.y),
          an = a.next,
          bp = b.prev;

      a.next = b;
      b.prev = a;

      a2.next = an;
      an.prev = a2;

      b2.next = a2;
      a2.prev = b2;

      bp.next = b2;
      b2.prev = bp;

      return b2;
  }

  // create a node and optionally link it with previous one (in a circular doubly linked list)
  function insertNode(i, x, y, last) {
      var p = new Node$1(i, x, y);

      if (!last) {
          p.prev = p;
          p.next = p;

      } else {
          p.next = last.next;
          p.prev = last;
          last.next.prev = p;
          last.next = p;
      }
      return p;
  }

  function removeNode(p) {
      p.next.prev = p.prev;
      p.prev.next = p.next;

      if (p.prevZ) p.prevZ.nextZ = p.nextZ;
      if (p.nextZ) p.nextZ.prevZ = p.prevZ;
  }

  function Node$1(i, x, y) {
      // vertex index in coordinates array
      this.i = i;

      // vertex coordinates
      this.x = x;
      this.y = y;

      // previous and next vertex nodes in a polygon ring
      this.prev = null;
      this.next = null;

      // z-order curve value
      this.z = null;

      // previous and next nodes in z-order
      this.prevZ = null;
      this.nextZ = null;

      // indicates whether this is a steiner point
      this.steiner = false;
  }

  // return a percentage difference between the polygon area and its triangulation area;
  // used to verify correctness of triangulation
  earcut.deviation = function (data, holeIndices, dim, triangles) {
      var hasHoles = holeIndices && holeIndices.length;
      var outerLen = hasHoles ? holeIndices[0] * dim : data.length;

      var polygonArea = Math.abs(signedArea(data, 0, outerLen, dim));
      if (hasHoles) {
          for (var i = 0, len = holeIndices.length; i < len; i++) {
              var start = holeIndices[i] * dim;
              var end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
              polygonArea -= Math.abs(signedArea(data, start, end, dim));
          }
      }

      var trianglesArea = 0;
      for (i = 0; i < triangles.length; i += 3) {
          var a = triangles[i] * dim;
          var b = triangles[i + 1] * dim;
          var c = triangles[i + 2] * dim;
          trianglesArea += Math.abs(
              (data[a] - data[c]) * (data[b + 1] - data[a + 1]) -
              (data[a] - data[b]) * (data[c + 1] - data[a + 1]));
      }

      return polygonArea === 0 && trianglesArea === 0 ? 0 :
          Math.abs((trianglesArea - polygonArea) / polygonArea);
  };

  function signedArea(data, start, end, dim) {
      var sum = 0;
      for (var i = start, j = end - dim; i < end; i += dim) {
          sum += (data[j] - data[i]) * (data[i + 1] + data[j + 1]);
          j = i;
      }
      return sum;
  }

  // turn a polygon in a multi-dimensional array form (e.g. as in GeoJSON) into a form Earcut accepts
  earcut.flatten = function (data) {
      var dim = data[0][0].length,
          result = {vertices: [], holes: [], dimensions: dim},
          holeIndex = 0;

      for (var i = 0; i < data.length; i++) {
          for (var j = 0; j < data[i].length; j++) {
              for (var d = 0; d < dim; d++) result.vertices.push(data[i][j][d]);
          }
          if (i > 0) {
              holeIndex += data[i - 1].length;
              result.holes.push(holeIndex);
          }
      }
      return result;
  };

  /**
   * Winding order defines the order of vertices for a triangle to be considered front-facing.
   *
   * @enum {Number}
   */
  var WindingOrder = {
    /**
     * Vertices are in clockwise order.
     *
     * @type {Number}
     * @constant
     */
    CLOCKWISE: WebGLConstants$1.CW,

    /**
     * Vertices are in counter-clockwise order.
     *
     * @type {Number}
     * @constant
     */
    COUNTER_CLOCKWISE: WebGLConstants$1.CCW,
  };

  /**
   * @private
   */
  WindingOrder.validate = function (windingOrder) {
    return (
      windingOrder === WindingOrder.CLOCKWISE ||
      windingOrder === WindingOrder.COUNTER_CLOCKWISE
    );
  };

  var WindingOrder$1 = Object.freeze(WindingOrder);

  var scaleToGeodeticHeightN = new Cartesian3();
  var scaleToGeodeticHeightP = new Cartesian3();

  /**
   * @private
   */
  var PolygonPipeline = {};

  /**
   * @exception {DeveloperError} At least three positions are required.
   */
  PolygonPipeline.computeArea2D = function (positions) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("positions", positions);
    Check.typeOf.number.greaterThanOrEquals(
      "positions.length",
      positions.length,
      3
    );
    //>>includeEnd('debug');

    var length = positions.length;
    var area = 0.0;

    for (var i0 = length - 1, i1 = 0; i1 < length; i0 = i1++) {
      var v0 = positions[i0];
      var v1 = positions[i1];

      area += v0.x * v1.y - v1.x * v0.y;
    }

    return area * 0.5;
  };

  /**
   * @returns {WindingOrder} The winding order.
   *
   * @exception {DeveloperError} At least three positions are required.
   */
  PolygonPipeline.computeWindingOrder2D = function (positions) {
    var area = PolygonPipeline.computeArea2D(positions);
    return area > 0.0 ? WindingOrder$1.COUNTER_CLOCKWISE : WindingOrder$1.CLOCKWISE;
  };

  /**
   * Triangulate a polygon.
   *
   * @param {Cartesian2[]} positions Cartesian2 array containing the vertices of the polygon
   * @param {Number[]} [holes] An array of the staring indices of the holes.
   * @returns {Number[]} Index array representing triangles that fill the polygon
   */
  PolygonPipeline.triangulate = function (positions, holes) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("positions", positions);
    //>>includeEnd('debug');

    var flattenedPositions = Cartesian2.packArray(positions);
    return earcut(flattenedPositions, holes, 2);
  };

  var subdivisionV0Scratch = new Cartesian3();
  var subdivisionV1Scratch = new Cartesian3();
  var subdivisionV2Scratch = new Cartesian3();
  var subdivisionS0Scratch = new Cartesian3();
  var subdivisionS1Scratch = new Cartesian3();
  var subdivisionS2Scratch = new Cartesian3();
  var subdivisionMidScratch = new Cartesian3();

  /**
   * Subdivides positions and raises points to the surface of the ellipsoid.
   *
   * @param {Ellipsoid} ellipsoid The ellipsoid the polygon in on.
   * @param {Cartesian3[]} positions An array of {@link Cartesian3} positions of the polygon.
   * @param {Number[]} indices An array of indices that determines the triangles in the polygon.
   * @param {Number} [granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   *
   * @exception {DeveloperError} At least three indices are required.
   * @exception {DeveloperError} The number of indices must be divisable by three.
   * @exception {DeveloperError} Granularity must be greater than zero.
   */
  PolygonPipeline.computeSubdivision = function (
    ellipsoid,
    positions,
    indices,
    granularity
  ) {
    granularity = defaultValue(granularity, CesiumMath.RADIANS_PER_DEGREE);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("ellipsoid", ellipsoid);
    Check.defined("positions", positions);
    Check.defined("indices", indices);
    Check.typeOf.number.greaterThanOrEquals("indices.length", indices.length, 3);
    Check.typeOf.number.equals("indices.length % 3", "0", indices.length % 3, 0);
    Check.typeOf.number.greaterThan("granularity", granularity, 0.0);
    //>>includeEnd('debug');

    // triangles that need (or might need) to be subdivided.
    var triangles = indices.slice(0);

    // New positions due to edge splits are appended to the positions list.
    var i;
    var length = positions.length;
    var subdividedPositions = new Array(length * 3);
    var q = 0;
    for (i = 0; i < length; i++) {
      var item = positions[i];
      subdividedPositions[q++] = item.x;
      subdividedPositions[q++] = item.y;
      subdividedPositions[q++] = item.z;
    }

    var subdividedIndices = [];

    // Used to make sure shared edges are not split more than once.
    var edges = {};

    var radius = ellipsoid.maximumRadius;
    var minDistance = CesiumMath.chordLength(granularity, radius);
    var minDistanceSqrd = minDistance * minDistance;

    while (triangles.length > 0) {
      var i2 = triangles.pop();
      var i1 = triangles.pop();
      var i0 = triangles.pop();

      var v0 = Cartesian3.fromArray(
        subdividedPositions,
        i0 * 3,
        subdivisionV0Scratch
      );
      var v1 = Cartesian3.fromArray(
        subdividedPositions,
        i1 * 3,
        subdivisionV1Scratch
      );
      var v2 = Cartesian3.fromArray(
        subdividedPositions,
        i2 * 3,
        subdivisionV2Scratch
      );

      var s0 = Cartesian3.multiplyByScalar(
        Cartesian3.normalize(v0, subdivisionS0Scratch),
        radius,
        subdivisionS0Scratch
      );
      var s1 = Cartesian3.multiplyByScalar(
        Cartesian3.normalize(v1, subdivisionS1Scratch),
        radius,
        subdivisionS1Scratch
      );
      var s2 = Cartesian3.multiplyByScalar(
        Cartesian3.normalize(v2, subdivisionS2Scratch),
        radius,
        subdivisionS2Scratch
      );

      var g0 = Cartesian3.magnitudeSquared(
        Cartesian3.subtract(s0, s1, subdivisionMidScratch)
      );
      var g1 = Cartesian3.magnitudeSquared(
        Cartesian3.subtract(s1, s2, subdivisionMidScratch)
      );
      var g2 = Cartesian3.magnitudeSquared(
        Cartesian3.subtract(s2, s0, subdivisionMidScratch)
      );

      var max = Math.max(g0, g1, g2);
      var edge;
      var mid;

      // if the max length squared of a triangle edge is greater than the chord length of squared
      // of the granularity, subdivide the triangle
      if (max > minDistanceSqrd) {
        if (g0 === max) {
          edge = Math.min(i0, i1) + " " + Math.max(i0, i1);

          i = edges[edge];
          if (!defined(i)) {
            mid = Cartesian3.add(v0, v1, subdivisionMidScratch);
            Cartesian3.multiplyByScalar(mid, 0.5, mid);
            subdividedPositions.push(mid.x, mid.y, mid.z);
            i = subdividedPositions.length / 3 - 1;
            edges[edge] = i;
          }

          triangles.push(i0, i, i2);
          triangles.push(i, i1, i2);
        } else if (g1 === max) {
          edge = Math.min(i1, i2) + " " + Math.max(i1, i2);

          i = edges[edge];
          if (!defined(i)) {
            mid = Cartesian3.add(v1, v2, subdivisionMidScratch);
            Cartesian3.multiplyByScalar(mid, 0.5, mid);
            subdividedPositions.push(mid.x, mid.y, mid.z);
            i = subdividedPositions.length / 3 - 1;
            edges[edge] = i;
          }

          triangles.push(i1, i, i0);
          triangles.push(i, i2, i0);
        } else if (g2 === max) {
          edge = Math.min(i2, i0) + " " + Math.max(i2, i0);

          i = edges[edge];
          if (!defined(i)) {
            mid = Cartesian3.add(v2, v0, subdivisionMidScratch);
            Cartesian3.multiplyByScalar(mid, 0.5, mid);
            subdividedPositions.push(mid.x, mid.y, mid.z);
            i = subdividedPositions.length / 3 - 1;
            edges[edge] = i;
          }

          triangles.push(i2, i, i1);
          triangles.push(i, i0, i1);
        }
      } else {
        subdividedIndices.push(i0);
        subdividedIndices.push(i1);
        subdividedIndices.push(i2);
      }
    }

    return new Geometry({
      attributes: {
        position: new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.DOUBLE,
          componentsPerAttribute: 3,
          values: subdividedPositions,
        }),
      },
      indices: subdividedIndices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    });
  };

  var subdivisionC0Scratch = new Cartographic();
  var subdivisionC1Scratch = new Cartographic();
  var subdivisionC2Scratch = new Cartographic();
  var subdivisionCartographicScratch = new Cartographic();

  /**
   * Subdivides positions on rhumb lines and raises points to the surface of the ellipsoid.
   *
   * @param {Ellipsoid} ellipsoid The ellipsoid the polygon in on.
   * @param {Cartesian3[]} positions An array of {@link Cartesian3} positions of the polygon.
   * @param {Number[]} indices An array of indices that determines the triangles in the polygon.
   * @param {Number} [granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   *
   * @exception {DeveloperError} At least three indices are required.
   * @exception {DeveloperError} The number of indices must be divisable by three.
   * @exception {DeveloperError} Granularity must be greater than zero.
   */
  PolygonPipeline.computeRhumbLineSubdivision = function (
    ellipsoid,
    positions,
    indices,
    granularity
  ) {
    granularity = defaultValue(granularity, CesiumMath.RADIANS_PER_DEGREE);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("ellipsoid", ellipsoid);
    Check.defined("positions", positions);
    Check.defined("indices", indices);
    Check.typeOf.number.greaterThanOrEquals("indices.length", indices.length, 3);
    Check.typeOf.number.equals("indices.length % 3", "0", indices.length % 3, 0);
    Check.typeOf.number.greaterThan("granularity", granularity, 0.0);
    //>>includeEnd('debug');

    // triangles that need (or might need) to be subdivided.
    var triangles = indices.slice(0);

    // New positions due to edge splits are appended to the positions list.
    var i;
    var length = positions.length;
    var subdividedPositions = new Array(length * 3);
    var q = 0;
    for (i = 0; i < length; i++) {
      var item = positions[i];
      subdividedPositions[q++] = item.x;
      subdividedPositions[q++] = item.y;
      subdividedPositions[q++] = item.z;
    }

    var subdividedIndices = [];

    // Used to make sure shared edges are not split more than once.
    var edges = {};

    var radius = ellipsoid.maximumRadius;
    var minDistance = CesiumMath.chordLength(granularity, radius);

    var rhumb0 = new EllipsoidRhumbLine(undefined, undefined, ellipsoid);
    var rhumb1 = new EllipsoidRhumbLine(undefined, undefined, ellipsoid);
    var rhumb2 = new EllipsoidRhumbLine(undefined, undefined, ellipsoid);

    while (triangles.length > 0) {
      var i2 = triangles.pop();
      var i1 = triangles.pop();
      var i0 = triangles.pop();

      var v0 = Cartesian3.fromArray(
        subdividedPositions,
        i0 * 3,
        subdivisionV0Scratch
      );
      var v1 = Cartesian3.fromArray(
        subdividedPositions,
        i1 * 3,
        subdivisionV1Scratch
      );
      var v2 = Cartesian3.fromArray(
        subdividedPositions,
        i2 * 3,
        subdivisionV2Scratch
      );

      var c0 = ellipsoid.cartesianToCartographic(v0, subdivisionC0Scratch);
      var c1 = ellipsoid.cartesianToCartographic(v1, subdivisionC1Scratch);
      var c2 = ellipsoid.cartesianToCartographic(v2, subdivisionC2Scratch);

      rhumb0.setEndPoints(c0, c1);
      var g0 = rhumb0.surfaceDistance;
      rhumb1.setEndPoints(c1, c2);
      var g1 = rhumb1.surfaceDistance;
      rhumb2.setEndPoints(c2, c0);
      var g2 = rhumb2.surfaceDistance;

      var max = Math.max(g0, g1, g2);
      var edge;
      var mid;
      var midHeight;
      var midCartesian3;

      // if the max length squared of a triangle edge is greater than granularity, subdivide the triangle
      if (max > minDistance) {
        if (g0 === max) {
          edge = Math.min(i0, i1) + " " + Math.max(i0, i1);

          i = edges[edge];
          if (!defined(i)) {
            mid = rhumb0.interpolateUsingFraction(
              0.5,
              subdivisionCartographicScratch
            );
            midHeight = (c0.height + c1.height) * 0.5;
            midCartesian3 = Cartesian3.fromRadians(
              mid.longitude,
              mid.latitude,
              midHeight,
              ellipsoid,
              subdivisionMidScratch
            );
            subdividedPositions.push(
              midCartesian3.x,
              midCartesian3.y,
              midCartesian3.z
            );
            i = subdividedPositions.length / 3 - 1;
            edges[edge] = i;
          }

          triangles.push(i0, i, i2);
          triangles.push(i, i1, i2);
        } else if (g1 === max) {
          edge = Math.min(i1, i2) + " " + Math.max(i1, i2);

          i = edges[edge];
          if (!defined(i)) {
            mid = rhumb1.interpolateUsingFraction(
              0.5,
              subdivisionCartographicScratch
            );
            midHeight = (c1.height + c2.height) * 0.5;
            midCartesian3 = Cartesian3.fromRadians(
              mid.longitude,
              mid.latitude,
              midHeight,
              ellipsoid,
              subdivisionMidScratch
            );
            subdividedPositions.push(
              midCartesian3.x,
              midCartesian3.y,
              midCartesian3.z
            );
            i = subdividedPositions.length / 3 - 1;
            edges[edge] = i;
          }

          triangles.push(i1, i, i0);
          triangles.push(i, i2, i0);
        } else if (g2 === max) {
          edge = Math.min(i2, i0) + " " + Math.max(i2, i0);

          i = edges[edge];
          if (!defined(i)) {
            mid = rhumb2.interpolateUsingFraction(
              0.5,
              subdivisionCartographicScratch
            );
            midHeight = (c2.height + c0.height) * 0.5;
            midCartesian3 = Cartesian3.fromRadians(
              mid.longitude,
              mid.latitude,
              midHeight,
              ellipsoid,
              subdivisionMidScratch
            );
            subdividedPositions.push(
              midCartesian3.x,
              midCartesian3.y,
              midCartesian3.z
            );
            i = subdividedPositions.length / 3 - 1;
            edges[edge] = i;
          }

          triangles.push(i2, i, i1);
          triangles.push(i, i0, i1);
        }
      } else {
        subdividedIndices.push(i0);
        subdividedIndices.push(i1);
        subdividedIndices.push(i2);
      }
    }

    return new Geometry({
      attributes: {
        position: new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.DOUBLE,
          componentsPerAttribute: 3,
          values: subdividedPositions,
        }),
      },
      indices: subdividedIndices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    });
  };

  /**
   * Scales each position of a geometry's position attribute to a height, in place.
   *
   * @param {Number[]} positions The array of numbers representing the positions to be scaled
   * @param {Number} [height=0.0] The desired height to add to the positions
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the positions lie.
   * @param {Boolean} [scaleToSurface=true] <code>true</code> if the positions need to be scaled to the surface before the height is added.
   * @returns {Number[]} The input array of positions, scaled to height
   */
  PolygonPipeline.scaleToGeodeticHeight = function (
    positions,
    height,
    ellipsoid,
    scaleToSurface
  ) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var n = scaleToGeodeticHeightN;
    var p = scaleToGeodeticHeightP;

    height = defaultValue(height, 0.0);
    scaleToSurface = defaultValue(scaleToSurface, true);

    if (defined(positions)) {
      var length = positions.length;

      for (var i = 0; i < length; i += 3) {
        Cartesian3.fromArray(positions, i, p);

        if (scaleToSurface) {
          p = ellipsoid.scaleToGeodeticSurface(p, p);
        }

        if (height !== 0) {
          n = ellipsoid.geodeticSurfaceNormal(p, n);

          Cartesian3.multiplyByScalar(n, height, n);
          Cartesian3.add(p, n, p);
        }

        positions[i] = p.x;
        positions[i + 1] = p.y;
        positions[i + 2] = p.z;
      }
    }

    return positions;
  };

  /**
   * A queue that can enqueue items at the end, and dequeue items from the front.
   *
   * @alias Queue
   * @constructor
   */
  function Queue() {
    this._array = [];
    this._offset = 0;
    this._length = 0;
  }

  Object.defineProperties(Queue.prototype, {
    /**
     * The length of the queue.
     *
     * @memberof Queue.prototype
     *
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._length;
      },
    },
  });

  /**
   * Enqueues the specified item.
   *
   * @param {*} item The item to enqueue.
   */
  Queue.prototype.enqueue = function (item) {
    this._array.push(item);
    this._length++;
  };

  /**
   * Dequeues an item.  Returns undefined if the queue is empty.
   *
   * @returns {*} The the dequeued item.
   */
  Queue.prototype.dequeue = function () {
    if (this._length === 0) {
      return undefined;
    }

    var array = this._array;
    var offset = this._offset;
    var item = array[offset];
    array[offset] = undefined;

    offset++;
    if (offset > 10 && offset * 2 > array.length) {
      //compact array
      this._array = array.slice(offset);
      offset = 0;
    }

    this._offset = offset;
    this._length--;

    return item;
  };

  /**
   * Returns the item at the front of the queue.  Returns undefined if the queue is empty.
   *
   * @returns {*} The item at the front of the queue.
   */
  Queue.prototype.peek = function () {
    if (this._length === 0) {
      return undefined;
    }

    return this._array[this._offset];
  };

  /**
   * Check whether this queue contains the specified item.
   *
   * @param {*} item The item to search for.
   */
  Queue.prototype.contains = function (item) {
    return this._array.indexOf(item) !== -1;
  };

  /**
   * Remove all items from the queue.
   */
  Queue.prototype.clear = function () {
    this._array.length = this._offset = this._length = 0;
  };

  /**
   * Sort the items in the queue in-place.
   *
   * @param {Queue.Comparator} compareFunction A function that defines the sort order.
   */
  Queue.prototype.sort = function (compareFunction) {
    if (this._offset > 0) {
      //compact array
      this._array = this._array.slice(this._offset);
      this._offset = 0;
    }

    this._array.sort(compareFunction);
  };

  /**
   * @private
   */
  var PolygonGeometryLibrary = {};

  PolygonGeometryLibrary.computeHierarchyPackedLength = function (
    polygonHierarchy
  ) {
    var numComponents = 0;
    var stack = [polygonHierarchy];
    while (stack.length > 0) {
      var hierarchy = stack.pop();
      if (!defined(hierarchy)) {
        continue;
      }

      numComponents += 2;

      var positions = hierarchy.positions;
      var holes = hierarchy.holes;

      if (defined(positions)) {
        numComponents += positions.length * Cartesian3.packedLength;
      }

      if (defined(holes)) {
        var length = holes.length;
        for (var i = 0; i < length; ++i) {
          stack.push(holes[i]);
        }
      }
    }

    return numComponents;
  };

  PolygonGeometryLibrary.packPolygonHierarchy = function (
    polygonHierarchy,
    array,
    startingIndex
  ) {
    var stack = [polygonHierarchy];
    while (stack.length > 0) {
      var hierarchy = stack.pop();
      if (!defined(hierarchy)) {
        continue;
      }

      var positions = hierarchy.positions;
      var holes = hierarchy.holes;

      array[startingIndex++] = defined(positions) ? positions.length : 0;
      array[startingIndex++] = defined(holes) ? holes.length : 0;

      if (defined(positions)) {
        var positionsLength = positions.length;
        for (var i = 0; i < positionsLength; ++i, startingIndex += 3) {
          Cartesian3.pack(positions[i], array, startingIndex);
        }
      }

      if (defined(holes)) {
        var holesLength = holes.length;
        for (var j = 0; j < holesLength; ++j) {
          stack.push(holes[j]);
        }
      }
    }

    return startingIndex;
  };

  PolygonGeometryLibrary.unpackPolygonHierarchy = function (
    array,
    startingIndex
  ) {
    var positionsLength = array[startingIndex++];
    var holesLength = array[startingIndex++];

    var positions = new Array(positionsLength);
    var holes = holesLength > 0 ? new Array(holesLength) : undefined;

    for (
      var i = 0;
      i < positionsLength;
      ++i, startingIndex += Cartesian3.packedLength
    ) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    for (var j = 0; j < holesLength; ++j) {
      holes[j] = PolygonGeometryLibrary.unpackPolygonHierarchy(
        array,
        startingIndex
      );
      startingIndex = holes[j].startingIndex;
      delete holes[j].startingIndex;
    }

    return {
      positions: positions,
      holes: holes,
      startingIndex: startingIndex,
    };
  };

  var distanceScratch$3 = new Cartesian3();
  function getPointAtDistance(p0, p1, distance, length) {
    Cartesian3.subtract(p1, p0, distanceScratch$3);
    Cartesian3.multiplyByScalar(
      distanceScratch$3,
      distance / length,
      distanceScratch$3
    );
    Cartesian3.add(p0, distanceScratch$3, distanceScratch$3);
    return [distanceScratch$3.x, distanceScratch$3.y, distanceScratch$3.z];
  }

  PolygonGeometryLibrary.subdivideLineCount = function (p0, p1, minDistance) {
    var distance = Cartesian3.distance(p0, p1);
    var n = distance / minDistance;
    var countDivide = Math.max(0, Math.ceil(CesiumMath.log2(n)));
    return Math.pow(2, countDivide);
  };

  var scratchCartographic0 = new Cartographic();
  var scratchCartographic1 = new Cartographic();
  var scratchCartographic2 = new Cartographic();
  var scratchCartesian0 = new Cartesian3();
  PolygonGeometryLibrary.subdivideRhumbLineCount = function (
    ellipsoid,
    p0,
    p1,
    minDistance
  ) {
    var c0 = ellipsoid.cartesianToCartographic(p0, scratchCartographic0);
    var c1 = ellipsoid.cartesianToCartographic(p1, scratchCartographic1);
    var rhumb = new EllipsoidRhumbLine(c0, c1, ellipsoid);
    var n = rhumb.surfaceDistance / minDistance;
    var countDivide = Math.max(0, Math.ceil(CesiumMath.log2(n)));
    return Math.pow(2, countDivide);
  };

  PolygonGeometryLibrary.subdivideLine = function (p0, p1, minDistance, result) {
    var numVertices = PolygonGeometryLibrary.subdivideLineCount(
      p0,
      p1,
      minDistance
    );
    var length = Cartesian3.distance(p0, p1);
    var distanceBetweenVertices = length / numVertices;

    if (!defined(result)) {
      result = [];
    }

    var positions = result;
    positions.length = numVertices * 3;

    var index = 0;
    for (var i = 0; i < numVertices; i++) {
      var p = getPointAtDistance(p0, p1, i * distanceBetweenVertices, length);
      positions[index++] = p[0];
      positions[index++] = p[1];
      positions[index++] = p[2];
    }

    return positions;
  };

  PolygonGeometryLibrary.subdivideRhumbLine = function (
    ellipsoid,
    p0,
    p1,
    minDistance,
    result
  ) {
    var c0 = ellipsoid.cartesianToCartographic(p0, scratchCartographic0);
    var c1 = ellipsoid.cartesianToCartographic(p1, scratchCartographic1);
    var rhumb = new EllipsoidRhumbLine(c0, c1, ellipsoid);

    var n = rhumb.surfaceDistance / minDistance;
    var countDivide = Math.max(0, Math.ceil(CesiumMath.log2(n)));
    var numVertices = Math.pow(2, countDivide);
    var distanceBetweenVertices = rhumb.surfaceDistance / numVertices;

    if (!defined(result)) {
      result = [];
    }

    var positions = result;
    positions.length = numVertices * 3;

    var index = 0;
    for (var i = 0; i < numVertices; i++) {
      var c = rhumb.interpolateUsingSurfaceDistance(
        i * distanceBetweenVertices,
        scratchCartographic2
      );
      var p = ellipsoid.cartographicToCartesian(c, scratchCartesian0);
      positions[index++] = p.x;
      positions[index++] = p.y;
      positions[index++] = p.z;
    }

    return positions;
  };

  var scaleToGeodeticHeightN1 = new Cartesian3();
  var scaleToGeodeticHeightN2 = new Cartesian3();
  var scaleToGeodeticHeightP1 = new Cartesian3();
  var scaleToGeodeticHeightP2 = new Cartesian3();

  PolygonGeometryLibrary.scaleToGeodeticHeightExtruded = function (
    geometry,
    maxHeight,
    minHeight,
    ellipsoid,
    perPositionHeight
  ) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var n1 = scaleToGeodeticHeightN1;
    var n2 = scaleToGeodeticHeightN2;
    var p = scaleToGeodeticHeightP1;
    var p2 = scaleToGeodeticHeightP2;

    if (
      defined(geometry) &&
      defined(geometry.attributes) &&
      defined(geometry.attributes.position)
    ) {
      var positions = geometry.attributes.position.values;
      var length = positions.length / 2;

      for (var i = 0; i < length; i += 3) {
        Cartesian3.fromArray(positions, i, p);

        ellipsoid.geodeticSurfaceNormal(p, n1);
        p2 = ellipsoid.scaleToGeodeticSurface(p, p2);
        n2 = Cartesian3.multiplyByScalar(n1, minHeight, n2);
        n2 = Cartesian3.add(p2, n2, n2);
        positions[i + length] = n2.x;
        positions[i + 1 + length] = n2.y;
        positions[i + 2 + length] = n2.z;

        if (perPositionHeight) {
          p2 = Cartesian3.clone(p, p2);
        }
        n2 = Cartesian3.multiplyByScalar(n1, maxHeight, n2);
        n2 = Cartesian3.add(p2, n2, n2);
        positions[i] = n2.x;
        positions[i + 1] = n2.y;
        positions[i + 2] = n2.z;
      }
    }
    return geometry;
  };

  PolygonGeometryLibrary.polygonOutlinesFromHierarchy = function (
    polygonHierarchy,
    scaleToEllipsoidSurface,
    ellipsoid
  ) {
    // create from a polygon hierarchy
    // Algorithm adapted from http://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
    var polygons = [];
    var queue = new Queue();
    queue.enqueue(polygonHierarchy);
    var i;
    var j;
    var length;
    while (queue.length !== 0) {
      var outerNode = queue.dequeue();
      var outerRing = outerNode.positions;
      if (scaleToEllipsoidSurface) {
        length = outerRing.length;
        for (i = 0; i < length; i++) {
          ellipsoid.scaleToGeodeticSurface(outerRing[i], outerRing[i]);
        }
      }
      outerRing = arrayRemoveDuplicates(
        outerRing,
        Cartesian3.equalsEpsilon,
        true
      );
      if (outerRing.length < 3) {
        continue;
      }

      var numChildren = outerNode.holes ? outerNode.holes.length : 0;
      // The outer polygon contains inner polygons
      for (i = 0; i < numChildren; i++) {
        var hole = outerNode.holes[i];
        var holePositions = hole.positions;
        if (scaleToEllipsoidSurface) {
          length = holePositions.length;
          for (j = 0; j < length; ++j) {
            ellipsoid.scaleToGeodeticSurface(holePositions[j], holePositions[j]);
          }
        }
        holePositions = arrayRemoveDuplicates(
          holePositions,
          Cartesian3.equalsEpsilon,
          true
        );
        if (holePositions.length < 3) {
          continue;
        }
        polygons.push(holePositions);

        var numGrandchildren = 0;
        if (defined(hole.holes)) {
          numGrandchildren = hole.holes.length;
        }

        for (j = 0; j < numGrandchildren; j++) {
          queue.enqueue(hole.holes[j]);
        }
      }

      polygons.push(outerRing);
    }

    return polygons;
  };

  PolygonGeometryLibrary.polygonsFromHierarchy = function (
    polygonHierarchy,
    projectPointsTo2D,
    scaleToEllipsoidSurface,
    ellipsoid
  ) {
    // create from a polygon hierarchy
    // Algorithm adapted from http://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
    var hierarchy = [];
    var polygons = [];

    var queue = new Queue();
    queue.enqueue(polygonHierarchy);

    while (queue.length !== 0) {
      var outerNode = queue.dequeue();
      var outerRing = outerNode.positions;
      var holes = outerNode.holes;

      var i;
      var length;
      if (scaleToEllipsoidSurface) {
        length = outerRing.length;
        for (i = 0; i < length; i++) {
          ellipsoid.scaleToGeodeticSurface(outerRing[i], outerRing[i]);
        }
      }

      outerRing = arrayRemoveDuplicates(
        outerRing,
        Cartesian3.equalsEpsilon,
        true
      );
      if (outerRing.length < 3) {
        continue;
      }

      var positions2D = projectPointsTo2D(outerRing);
      if (!defined(positions2D)) {
        continue;
      }
      var holeIndices = [];

      var originalWindingOrder = PolygonPipeline.computeWindingOrder2D(
        positions2D
      );
      if (originalWindingOrder === WindingOrder$1.CLOCKWISE) {
        positions2D.reverse();
        outerRing = outerRing.slice().reverse();
      }

      var positions = outerRing.slice();
      var numChildren = defined(holes) ? holes.length : 0;
      var polygonHoles = [];
      var j;

      for (i = 0; i < numChildren; i++) {
        var hole = holes[i];
        var holePositions = hole.positions;
        if (scaleToEllipsoidSurface) {
          length = holePositions.length;
          for (j = 0; j < length; ++j) {
            ellipsoid.scaleToGeodeticSurface(holePositions[j], holePositions[j]);
          }
        }

        holePositions = arrayRemoveDuplicates(
          holePositions,
          Cartesian3.equalsEpsilon,
          true
        );
        if (holePositions.length < 3) {
          continue;
        }

        var holePositions2D = projectPointsTo2D(holePositions);
        if (!defined(holePositions2D)) {
          continue;
        }

        originalWindingOrder = PolygonPipeline.computeWindingOrder2D(
          holePositions2D
        );
        if (originalWindingOrder === WindingOrder$1.CLOCKWISE) {
          holePositions2D.reverse();
          holePositions = holePositions.slice().reverse();
        }

        polygonHoles.push(holePositions);
        holeIndices.push(positions.length);
        positions = positions.concat(holePositions);
        positions2D = positions2D.concat(holePositions2D);

        var numGrandchildren = 0;
        if (defined(hole.holes)) {
          numGrandchildren = hole.holes.length;
        }

        for (j = 0; j < numGrandchildren; j++) {
          queue.enqueue(hole.holes[j]);
        }
      }

      hierarchy.push({
        outerRing: outerRing,
        holes: polygonHoles,
      });
      polygons.push({
        positions: positions,
        positions2D: positions2D,
        holes: holeIndices,
      });
    }

    return {
      hierarchy: hierarchy,
      polygons: polygons,
    };
  };

  var computeBoundingRectangleCartesian2 = new Cartesian2();
  var computeBoundingRectangleCartesian3 = new Cartesian3();
  var computeBoundingRectangleQuaternion = new Quaternion();
  var computeBoundingRectangleMatrix3 = new Matrix3();
  PolygonGeometryLibrary.computeBoundingRectangle = function (
    planeNormal,
    projectPointTo2D,
    positions,
    angle,
    result
  ) {
    var rotation = Quaternion.fromAxisAngle(
      planeNormal,
      angle,
      computeBoundingRectangleQuaternion
    );
    var textureMatrix = Matrix3.fromQuaternion(
      rotation,
      computeBoundingRectangleMatrix3
    );

    var minX = Number.POSITIVE_INFINITY;
    var maxX = Number.NEGATIVE_INFINITY;
    var minY = Number.POSITIVE_INFINITY;
    var maxY = Number.NEGATIVE_INFINITY;

    var length = positions.length;
    for (var i = 0; i < length; ++i) {
      var p = Cartesian3.clone(positions[i], computeBoundingRectangleCartesian3);
      Matrix3.multiplyByVector(textureMatrix, p, p);
      var st = projectPointTo2D(p, computeBoundingRectangleCartesian2);

      if (defined(st)) {
        minX = Math.min(minX, st.x);
        maxX = Math.max(maxX, st.x);

        minY = Math.min(minY, st.y);
        maxY = Math.max(maxY, st.y);
      }
    }

    result.x = minX;
    result.y = minY;
    result.width = maxX - minX;
    result.height = maxY - minY;
    return result;
  };

  PolygonGeometryLibrary.createGeometryFromPositions = function (
    ellipsoid,
    polygon,
    granularity,
    perPositionHeight,
    vertexFormat,
    arcType
  ) {
    var indices = PolygonPipeline.triangulate(polygon.positions2D, polygon.holes);

    /* If polygon is completely unrenderable, just use the first three vertices */
    if (indices.length < 3) {
      indices = [0, 1, 2];
    }

    var positions = polygon.positions;

    if (perPositionHeight) {
      var length = positions.length;
      var flattenedPositions = new Array(length * 3);
      var index = 0;
      for (var i = 0; i < length; i++) {
        var p = positions[i];
        flattenedPositions[index++] = p.x;
        flattenedPositions[index++] = p.y;
        flattenedPositions[index++] = p.z;
      }
      var geometry = new Geometry({
        attributes: {
          position: new GeometryAttribute({
            componentDatatype: ComponentDatatype$1.DOUBLE,
            componentsPerAttribute: 3,
            values: flattenedPositions,
          }),
        },
        indices: indices,
        primitiveType: PrimitiveType$1.TRIANGLES,
      });

      if (vertexFormat.normal) {
        return GeometryPipeline.computeNormal(geometry);
      }

      return geometry;
    }

    if (arcType === ArcType$1.GEODESIC) {
      return PolygonPipeline.computeSubdivision(
        ellipsoid,
        positions,
        indices,
        granularity
      );
    } else if (arcType === ArcType$1.RHUMB) {
      return PolygonPipeline.computeRhumbLineSubdivision(
        ellipsoid,
        positions,
        indices,
        granularity
      );
    }
  };

  var computeWallIndicesSubdivided = [];
  var p1Scratch$1 = new Cartesian3();
  var p2Scratch$1 = new Cartesian3();

  PolygonGeometryLibrary.computeWallGeometry = function (
    positions,
    ellipsoid,
    granularity,
    perPositionHeight,
    arcType
  ) {
    var edgePositions;
    var topEdgeLength;
    var i;
    var p1;
    var p2;

    var length = positions.length;
    var index = 0;

    if (!perPositionHeight) {
      var minDistance = CesiumMath.chordLength(
        granularity,
        ellipsoid.maximumRadius
      );

      var numVertices = 0;
      if (arcType === ArcType$1.GEODESIC) {
        for (i = 0; i < length; i++) {
          numVertices += PolygonGeometryLibrary.subdivideLineCount(
            positions[i],
            positions[(i + 1) % length],
            minDistance
          );
        }
      } else if (arcType === ArcType$1.RHUMB) {
        for (i = 0; i < length; i++) {
          numVertices += PolygonGeometryLibrary.subdivideRhumbLineCount(
            ellipsoid,
            positions[i],
            positions[(i + 1) % length],
            minDistance
          );
        }
      }

      topEdgeLength = (numVertices + length) * 3;
      edgePositions = new Array(topEdgeLength * 2);
      for (i = 0; i < length; i++) {
        p1 = positions[i];
        p2 = positions[(i + 1) % length];

        var tempPositions;
        if (arcType === ArcType$1.GEODESIC) {
          tempPositions = PolygonGeometryLibrary.subdivideLine(
            p1,
            p2,
            minDistance,
            computeWallIndicesSubdivided
          );
        } else if (arcType === ArcType$1.RHUMB) {
          tempPositions = PolygonGeometryLibrary.subdivideRhumbLine(
            ellipsoid,
            p1,
            p2,
            minDistance,
            computeWallIndicesSubdivided
          );
        }
        var tempPositionsLength = tempPositions.length;
        for (var j = 0; j < tempPositionsLength; ++j, ++index) {
          edgePositions[index] = tempPositions[j];
          edgePositions[index + topEdgeLength] = tempPositions[j];
        }

        edgePositions[index] = p2.x;
        edgePositions[index + topEdgeLength] = p2.x;
        ++index;

        edgePositions[index] = p2.y;
        edgePositions[index + topEdgeLength] = p2.y;
        ++index;

        edgePositions[index] = p2.z;
        edgePositions[index + topEdgeLength] = p2.z;
        ++index;
      }
    } else {
      topEdgeLength = length * 3 * 2;
      edgePositions = new Array(topEdgeLength * 2);
      for (i = 0; i < length; i++) {
        p1 = positions[i];
        p2 = positions[(i + 1) % length];
        edgePositions[index] = edgePositions[index + topEdgeLength] = p1.x;
        ++index;
        edgePositions[index] = edgePositions[index + topEdgeLength] = p1.y;
        ++index;
        edgePositions[index] = edgePositions[index + topEdgeLength] = p1.z;
        ++index;
        edgePositions[index] = edgePositions[index + topEdgeLength] = p2.x;
        ++index;
        edgePositions[index] = edgePositions[index + topEdgeLength] = p2.y;
        ++index;
        edgePositions[index] = edgePositions[index + topEdgeLength] = p2.z;
        ++index;
      }
    }

    length = edgePositions.length;
    var indices = IndexDatatype$1.createTypedArray(
      length / 3,
      length - positions.length * 6
    );
    var edgeIndex = 0;
    length /= 6;

    for (i = 0; i < length; i++) {
      var UL = i;
      var UR = UL + 1;
      var LL = UL + length;
      var LR = LL + 1;

      p1 = Cartesian3.fromArray(edgePositions, UL * 3, p1Scratch$1);
      p2 = Cartesian3.fromArray(edgePositions, UR * 3, p2Scratch$1);
      if (
        Cartesian3.equalsEpsilon(
          p1,
          p2,
          CesiumMath.EPSILON10,
          CesiumMath.EPSILON10
        )
      ) {
        //skip corner
        continue;
      }

      indices[edgeIndex++] = UL;
      indices[edgeIndex++] = LL;
      indices[edgeIndex++] = UR;
      indices[edgeIndex++] = UR;
      indices[edgeIndex++] = LL;
      indices[edgeIndex++] = LR;
    }

    return new Geometry({
      attributes: new GeometryAttributes({
        position: new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.DOUBLE,
          componentsPerAttribute: 3,
          values: edgePositions,
        }),
      }),
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    });
  };

  var scratchPosition$1 = new Cartesian3();
  var scratchBR = new BoundingRectangle();
  var stScratch = new Cartesian2();
  var textureCoordinatesOrigin = new Cartesian2();
  var scratchNormal$3 = new Cartesian3();
  var scratchTangent$1 = new Cartesian3();
  var scratchBitangent$1 = new Cartesian3();
  var centerScratch = new Cartesian3();
  var axis1Scratch = new Cartesian3();
  var axis2Scratch = new Cartesian3();
  var quaternionScratch$1 = new Quaternion();
  var textureMatrixScratch$1 = new Matrix3();
  var tangentRotationScratch = new Matrix3();
  var surfaceNormalScratch = new Cartesian3();

  function createGeometryFromPolygon(
    polygon,
    vertexFormat,
    boundingRectangle,
    stRotation,
    projectPointTo2D,
    normal,
    tangent,
    bitangent
  ) {
    var positions = polygon.positions;
    var indices = PolygonPipeline.triangulate(polygon.positions2D, polygon.holes);

    /* If polygon is completely unrenderable, just use the first three vertices */
    if (indices.length < 3) {
      indices = [0, 1, 2];
    }

    var newIndices = IndexDatatype$1.createTypedArray(
      positions.length,
      indices.length
    );
    newIndices.set(indices);

    var textureMatrix = textureMatrixScratch$1;
    if (stRotation !== 0.0) {
      var rotation = Quaternion.fromAxisAngle(
        normal,
        stRotation,
        quaternionScratch$1
      );
      textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrix);

      if (vertexFormat.tangent || vertexFormat.bitangent) {
        rotation = Quaternion.fromAxisAngle(
          normal,
          -stRotation,
          quaternionScratch$1
        );
        var tangentRotation = Matrix3.fromQuaternion(
          rotation,
          tangentRotationScratch
        );

        tangent = Cartesian3.normalize(
          Matrix3.multiplyByVector(tangentRotation, tangent, tangent),
          tangent
        );
        if (vertexFormat.bitangent) {
          bitangent = Cartesian3.normalize(
            Cartesian3.cross(normal, tangent, bitangent),
            bitangent
          );
        }
      }
    } else {
      textureMatrix = Matrix3.clone(Matrix3.IDENTITY, textureMatrix);
    }

    var stOrigin = textureCoordinatesOrigin;
    if (vertexFormat.st) {
      stOrigin.x = boundingRectangle.x;
      stOrigin.y = boundingRectangle.y;
    }

    var length = positions.length;
    var size = length * 3;
    var flatPositions = new Float64Array(size);
    var normals = vertexFormat.normal ? new Float32Array(size) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(size) : undefined;
    var bitangents = vertexFormat.bitangent ? new Float32Array(size) : undefined;
    var textureCoordinates = vertexFormat.st
      ? new Float32Array(length * 2)
      : undefined;

    var positionIndex = 0;
    var normalIndex = 0;
    var bitangentIndex = 0;
    var tangentIndex = 0;
    var stIndex = 0;

    for (var i = 0; i < length; i++) {
      var position = positions[i];
      flatPositions[positionIndex++] = position.x;
      flatPositions[positionIndex++] = position.y;
      flatPositions[positionIndex++] = position.z;

      if (vertexFormat.st) {
        var p = Matrix3.multiplyByVector(
          textureMatrix,
          position,
          scratchPosition$1
        );
        var st = projectPointTo2D(p, stScratch);
        Cartesian2.subtract(st, stOrigin, st);

        var stx = CesiumMath.clamp(st.x / boundingRectangle.width, 0, 1);
        var sty = CesiumMath.clamp(st.y / boundingRectangle.height, 0, 1);
        textureCoordinates[stIndex++] = stx;
        textureCoordinates[stIndex++] = sty;
      }

      if (vertexFormat.normal) {
        normals[normalIndex++] = normal.x;
        normals[normalIndex++] = normal.y;
        normals[normalIndex++] = normal.z;
      }

      if (vertexFormat.tangent) {
        tangents[tangentIndex++] = tangent.x;
        tangents[tangentIndex++] = tangent.y;
        tangents[tangentIndex++] = tangent.z;
      }

      if (vertexFormat.bitangent) {
        bitangents[bitangentIndex++] = bitangent.x;
        bitangents[bitangentIndex++] = bitangent.y;
        bitangents[bitangentIndex++] = bitangent.z;
      }
    }

    var attributes = new GeometryAttributes();

    if (vertexFormat.position) {
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: flatPositions,
      });
    }

    if (vertexFormat.normal) {
      attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: normals,
      });
    }

    if (vertexFormat.tangent) {
      attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: tangents,
      });
    }

    if (vertexFormat.bitangent) {
      attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: bitangents,
      });
    }

    if (vertexFormat.st) {
      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: textureCoordinates,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: newIndices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    });
  }

  /**
   * A description of a polygon composed of arbitrary coplanar positions.
   *
   * @alias CoplanarPolygonGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {PolygonHierarchy} options.polygonHierarchy A polygon hierarchy that can include holes.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates, in radians. A positive rotation is counter-clockwise.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   *
   * @example
   * var polygon = new Cesium.CoplanarPolygonGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArrayHeights([
   *      -90.0, 30.0, 0.0,
   *      -90.0, 30.0, 1000.0,
   *      -80.0, 30.0, 1000.0,
   *      -80.0, 30.0, 0.0
   *   ])
   * });
   * var geometry = Cesium.CoplanarPolygonGeometry.createGeometry(polygon);
   *
   * @see CoplanarPolygonGeometry.createGeometry
   */
  function CoplanarPolygonGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var polygonHierarchy = options.polygonHierarchy;
    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.polygonHierarchy", polygonHierarchy);
    //>>includeEnd('debug');

    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);
    this._vertexFormat = VertexFormat.clone(vertexFormat);
    this._polygonHierarchy = polygonHierarchy;
    this._stRotation = defaultValue(options.stRotation, 0.0);
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._workerName = "createCoplanarPolygonGeometry";

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      PolygonGeometryLibrary.computeHierarchyPackedLength(polygonHierarchy) +
      VertexFormat.packedLength +
      Ellipsoid.packedLength +
      2;
  }

  /**
   * A description of a coplanar polygon from an array of positions.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that defined the corner points of the polygon.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates, in radians. A positive rotation is counter-clockwise.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @returns {CoplanarPolygonGeometry}
   *
   * @example
   * // create a polygon from points
   * var polygon = Cesium.CoplanarPolygonGeometry.fromPositions({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     -72.0, 40.0,
   *     -70.0, 35.0,
   *     -75.0, 30.0,
   *     -70.0, 30.0,
   *     -68.0, 40.0
   *   ])
   * });
   * var geometry = Cesium.PolygonGeometry.createGeometry(polygon);
   *
   * @see PolygonGeometry#createGeometry
   */
  CoplanarPolygonGeometry.fromPositions = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.positions", options.positions);
    //>>includeEnd('debug');

    var newOptions = {
      polygonHierarchy: {
        positions: options.positions,
      },
      vertexFormat: options.vertexFormat,
      stRotation: options.stRotation,
      ellipsoid: options.ellipsoid,
    };
    return new CoplanarPolygonGeometry(newOptions);
  };

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CoplanarPolygonGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CoplanarPolygonGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    startingIndex = PolygonGeometryLibrary.packPolygonHierarchy(
      value._polygonHierarchy,
      array,
      startingIndex
    );

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._stRotation;
    array[startingIndex] = value.packedLength;

    return array;
  };

  var scratchEllipsoid$2 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchVertexFormat$2 = new VertexFormat();
  var scratchOptions$6 = {
    polygonHierarchy: {},
  };
  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CoplanarPolygonGeometry} [result] The object into which to store the result.
   * @returns {CoplanarPolygonGeometry} The modified result parameter or a new CoplanarPolygonGeometry instance if one was not provided.
   */
  CoplanarPolygonGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var polygonHierarchy = PolygonGeometryLibrary.unpackPolygonHierarchy(
      array,
      startingIndex
    );
    startingIndex = polygonHierarchy.startingIndex;
    delete polygonHierarchy.startingIndex;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$2);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$2
    );
    startingIndex += VertexFormat.packedLength;

    var stRotation = array[startingIndex++];
    var packedLength = array[startingIndex];

    if (!defined(result)) {
      result = new CoplanarPolygonGeometry(scratchOptions$6);
    }

    result._polygonHierarchy = polygonHierarchy;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._stRotation = stRotation;
    result.packedLength = packedLength;
    return result;
  };

  /**
   * Computes the geometric representation of an arbitrary coplanar polygon, including its vertices, indices, and a bounding sphere.
   *
   * @param {CoplanarPolygonGeometry} polygonGeometry A description of the polygon.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CoplanarPolygonGeometry.createGeometry = function (polygonGeometry) {
    var vertexFormat = polygonGeometry._vertexFormat;
    var polygonHierarchy = polygonGeometry._polygonHierarchy;
    var stRotation = polygonGeometry._stRotation;

    var outerPositions = polygonHierarchy.positions;
    outerPositions = arrayRemoveDuplicates(
      outerPositions,
      Cartesian3.equalsEpsilon,
      true
    );
    if (outerPositions.length < 3) {
      return;
    }

    var normal = scratchNormal$3;
    var tangent = scratchTangent$1;
    var bitangent = scratchBitangent$1;
    var axis1 = axis1Scratch;
    var axis2 = axis2Scratch;

    var validGeometry = CoplanarPolygonGeometryLibrary.computeProjectTo2DArguments(
      outerPositions,
      centerScratch,
      axis1,
      axis2
    );
    if (!validGeometry) {
      return undefined;
    }

    normal = Cartesian3.cross(axis1, axis2, normal);
    normal = Cartesian3.normalize(normal, normal);

    if (
      !Cartesian3.equalsEpsilon(
        centerScratch,
        Cartesian3.ZERO,
        CesiumMath.EPSILON6
      )
    ) {
      var surfaceNormal = polygonGeometry._ellipsoid.geodeticSurfaceNormal(
        centerScratch,
        surfaceNormalScratch
      );
      if (Cartesian3.dot(normal, surfaceNormal) < 0) {
        normal = Cartesian3.negate(normal, normal);
        axis1 = Cartesian3.negate(axis1, axis1);
      }
    }

    var projectPoints = CoplanarPolygonGeometryLibrary.createProjectPointsTo2DFunction(
      centerScratch,
      axis1,
      axis2
    );
    var projectPoint = CoplanarPolygonGeometryLibrary.createProjectPointTo2DFunction(
      centerScratch,
      axis1,
      axis2
    );

    if (vertexFormat.tangent) {
      tangent = Cartesian3.clone(axis1, tangent);
    }
    if (vertexFormat.bitangent) {
      bitangent = Cartesian3.clone(axis2, bitangent);
    }

    var results = PolygonGeometryLibrary.polygonsFromHierarchy(
      polygonHierarchy,
      projectPoints,
      false
    );
    var hierarchy = results.hierarchy;
    var polygons = results.polygons;

    if (hierarchy.length === 0) {
      return;
    }
    outerPositions = hierarchy[0].outerRing;

    var boundingSphere = BoundingSphere.fromPoints(outerPositions);
    var boundingRectangle = PolygonGeometryLibrary.computeBoundingRectangle(
      normal,
      projectPoint,
      outerPositions,
      stRotation,
      scratchBR
    );

    var geometries = [];
    for (var i = 0; i < polygons.length; i++) {
      var geometryInstance = new GeometryInstance({
        geometry: createGeometryFromPolygon(
          polygons[i],
          vertexFormat,
          boundingRectangle,
          stRotation,
          projectPoint,
          normal,
          tangent,
          bitangent
        ),
      });

      geometries.push(geometryInstance);
    }

    var geometry = GeometryPipeline.combineInstances(geometries)[0];
    geometry.attributes.position.values = new Float64Array(
      geometry.attributes.position.values
    );
    geometry.indices = IndexDatatype$1.createTypedArray(
      geometry.attributes.position.values.length / 3,
      geometry.indices
    );

    var attributes = geometry.attributes;
    if (!vertexFormat.position) {
      delete attributes.position;
    }
    return new Geometry({
      attributes: attributes,
      indices: geometry.indices,
      primitiveType: geometry.primitiveType,
      boundingSphere: boundingSphere,
    });
  };

  function createGeometryFromPositions(positions) {
    var length = positions.length;
    var flatPositions = new Float64Array(length * 3);
    var indices = IndexDatatype$1.createTypedArray(length, length * 2);

    var positionIndex = 0;
    var index = 0;

    for (var i = 0; i < length; i++) {
      var position = positions[i];
      flatPositions[positionIndex++] = position.x;
      flatPositions[positionIndex++] = position.y;
      flatPositions[positionIndex++] = position.z;

      indices[index++] = i;
      indices[index++] = (i + 1) % length;
    }

    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: flatPositions,
      }),
    });

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
    });
  }

  /**
   * A description of the outline of a polygon composed of arbitrary coplanar positions.
   *
   * @alias CoplanarPolygonOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {PolygonHierarchy} options.polygonHierarchy A polygon hierarchy that can include holes.
   *
   * @see CoplanarPolygonOutlineGeometry.createGeometry
   *
   * @example
   * var polygonOutline = new Cesium.CoplanarPolygonOutlineGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArrayHeights([
   *      -90.0, 30.0, 0.0,
   *      -90.0, 30.0, 1000.0,
   *      -80.0, 30.0, 1000.0,
   *      -80.0, 30.0, 0.0
   *   ])
   * });
   * var geometry = Cesium.CoplanarPolygonOutlineGeometry.createGeometry(polygonOutline);
   */
  function CoplanarPolygonOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var polygonHierarchy = options.polygonHierarchy;
    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.polygonHierarchy", polygonHierarchy);
    //>>includeEnd('debug');

    this._polygonHierarchy = polygonHierarchy;
    this._workerName = "createCoplanarPolygonOutlineGeometry";

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      PolygonGeometryLibrary.computeHierarchyPackedLength(polygonHierarchy) + 1;
  }

  /**
   * A description of a coplanar polygon outline from an array of positions.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that defined the corner points of the polygon.
   * @returns {CoplanarPolygonOutlineGeometry}
   */
  CoplanarPolygonOutlineGeometry.fromPositions = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.positions", options.positions);
    //>>includeEnd('debug');

    var newOptions = {
      polygonHierarchy: {
        positions: options.positions,
      },
    };
    return new CoplanarPolygonOutlineGeometry(newOptions);
  };

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CoplanarPolygonOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CoplanarPolygonOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    startingIndex = PolygonGeometryLibrary.packPolygonHierarchy(
      value._polygonHierarchy,
      array,
      startingIndex
    );

    array[startingIndex] = value.packedLength;

    return array;
  };

  var scratchOptions$7 = {
    polygonHierarchy: {},
  };
  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CoplanarPolygonOutlineGeometry} [result] The object into which to store the result.
   * @returns {CoplanarPolygonOutlineGeometry} The modified result parameter or a new CoplanarPolygonOutlineGeometry instance if one was not provided.
   */
  CoplanarPolygonOutlineGeometry.unpack = function (
    array,
    startingIndex,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var polygonHierarchy = PolygonGeometryLibrary.unpackPolygonHierarchy(
      array,
      startingIndex
    );
    startingIndex = polygonHierarchy.startingIndex;
    delete polygonHierarchy.startingIndex;
    var packedLength = array[startingIndex];

    if (!defined(result)) {
      result = new CoplanarPolygonOutlineGeometry(scratchOptions$7);
    }

    result._polygonHierarchy = polygonHierarchy;
    result.packedLength = packedLength;

    return result;
  };

  /**
   * Computes the geometric representation of an arbitrary coplanar polygon, including its vertices, indices, and a bounding sphere.
   *
   * @param {CoplanarPolygonOutlineGeometry} polygonGeometry A description of the polygon.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CoplanarPolygonOutlineGeometry.createGeometry = function (polygonGeometry) {
    var polygonHierarchy = polygonGeometry._polygonHierarchy;

    var outerPositions = polygonHierarchy.positions;
    outerPositions = arrayRemoveDuplicates(
      outerPositions,
      Cartesian3.equalsEpsilon,
      true
    );
    if (outerPositions.length < 3) {
      return;
    }
    var isValid = CoplanarPolygonGeometryLibrary.validOutline(outerPositions);
    if (!isValid) {
      return undefined;
    }

    var polygons = PolygonGeometryLibrary.polygonOutlinesFromHierarchy(
      polygonHierarchy,
      false
    );

    if (polygons.length === 0) {
      return undefined;
    }

    var geometries = [];

    for (var i = 0; i < polygons.length; i++) {
      var geometryInstance = new GeometryInstance({
        geometry: createGeometryFromPositions(polygons[i]),
      });
      geometries.push(geometryInstance);
    }

    var geometry = GeometryPipeline.combineInstances(geometries)[0];
    var boundingSphere = BoundingSphere.fromPoints(polygonHierarchy.positions);

    return new Geometry({
      attributes: geometry.attributes,
      indices: geometry.indices,
      primitiveType: geometry.primitiveType,
      boundingSphere: boundingSphere,
    });
  };

  /**
   * Style options for corners.
   *
   * @demo The {@link https://sandcastle.cesium.com/index.html?src=Corridor.html&label=Geometries|Corridor Demo}
   * demonstrates the three corner types, as used by {@link CorridorGraphics}.
   *
   * @enum {Number}
   */
  var CornerType = {
    /**
     * <img src="Images/CornerTypeRounded.png" style="vertical-align: middle;" width="186" height="189" />
     *
     * Corner has a smooth edge.
     * @type {Number}
     * @constant
     */
    ROUNDED: 0,

    /**
     * <img src="Images/CornerTypeMitered.png" style="vertical-align: middle;" width="186" height="189" />
     *
     * Corner point is the intersection of adjacent edges.
     * @type {Number}
     * @constant
     */
    MITERED: 1,

    /**
     * <img src="Images/CornerTypeBeveled.png" style="vertical-align: middle;" width="186" height="189" />
     *
     * Corner is clipped.
     * @type {Number}
     * @constant
     */
    BEVELED: 2,
  };
  var CornerType$1 = Object.freeze(CornerType);

  function setConstants(ellipsoidGeodesic) {
    var uSquared = ellipsoidGeodesic._uSquared;
    var a = ellipsoidGeodesic._ellipsoid.maximumRadius;
    var b = ellipsoidGeodesic._ellipsoid.minimumRadius;
    var f = (a - b) / a;

    var cosineHeading = Math.cos(ellipsoidGeodesic._startHeading);
    var sineHeading = Math.sin(ellipsoidGeodesic._startHeading);

    var tanU = (1 - f) * Math.tan(ellipsoidGeodesic._start.latitude);

    var cosineU = 1.0 / Math.sqrt(1.0 + tanU * tanU);
    var sineU = cosineU * tanU;

    var sigma = Math.atan2(tanU, cosineHeading);

    var sineAlpha = cosineU * sineHeading;
    var sineSquaredAlpha = sineAlpha * sineAlpha;

    var cosineSquaredAlpha = 1.0 - sineSquaredAlpha;
    var cosineAlpha = Math.sqrt(cosineSquaredAlpha);

    var u2Over4 = uSquared / 4.0;
    var u4Over16 = u2Over4 * u2Over4;
    var u6Over64 = u4Over16 * u2Over4;
    var u8Over256 = u4Over16 * u4Over16;

    var a0 =
      1.0 +
      u2Over4 -
      (3.0 * u4Over16) / 4.0 +
      (5.0 * u6Over64) / 4.0 -
      (175.0 * u8Over256) / 64.0;
    var a1 = 1.0 - u2Over4 + (15.0 * u4Over16) / 8.0 - (35.0 * u6Over64) / 8.0;
    var a2 = 1.0 - 3.0 * u2Over4 + (35.0 * u4Over16) / 4.0;
    var a3 = 1.0 - 5.0 * u2Over4;

    var distanceRatio =
      a0 * sigma -
      (a1 * Math.sin(2.0 * sigma) * u2Over4) / 2.0 -
      (a2 * Math.sin(4.0 * sigma) * u4Over16) / 16.0 -
      (a3 * Math.sin(6.0 * sigma) * u6Over64) / 48.0 -
      (Math.sin(8.0 * sigma) * 5.0 * u8Over256) / 512;

    var constants = ellipsoidGeodesic._constants;

    constants.a = a;
    constants.b = b;
    constants.f = f;
    constants.cosineHeading = cosineHeading;
    constants.sineHeading = sineHeading;
    constants.tanU = tanU;
    constants.cosineU = cosineU;
    constants.sineU = sineU;
    constants.sigma = sigma;
    constants.sineAlpha = sineAlpha;
    constants.sineSquaredAlpha = sineSquaredAlpha;
    constants.cosineSquaredAlpha = cosineSquaredAlpha;
    constants.cosineAlpha = cosineAlpha;
    constants.u2Over4 = u2Over4;
    constants.u4Over16 = u4Over16;
    constants.u6Over64 = u6Over64;
    constants.u8Over256 = u8Over256;
    constants.a0 = a0;
    constants.a1 = a1;
    constants.a2 = a2;
    constants.a3 = a3;
    constants.distanceRatio = distanceRatio;
  }

  function computeC(f, cosineSquaredAlpha) {
    return (
      (f * cosineSquaredAlpha * (4.0 + f * (4.0 - 3.0 * cosineSquaredAlpha))) /
      16.0
    );
  }

  function computeDeltaLambda(
    f,
    sineAlpha,
    cosineSquaredAlpha,
    sigma,
    sineSigma,
    cosineSigma,
    cosineTwiceSigmaMidpoint
  ) {
    var C = computeC(f, cosineSquaredAlpha);

    return (
      (1.0 - C) *
      f *
      sineAlpha *
      (sigma +
        C *
          sineSigma *
          (cosineTwiceSigmaMidpoint +
            C *
              cosineSigma *
              (2.0 * cosineTwiceSigmaMidpoint * cosineTwiceSigmaMidpoint - 1.0)))
    );
  }

  function vincentyInverseFormula(
    ellipsoidGeodesic,
    major,
    minor,
    firstLongitude,
    firstLatitude,
    secondLongitude,
    secondLatitude
  ) {
    var eff = (major - minor) / major;
    var l = secondLongitude - firstLongitude;

    var u1 = Math.atan((1 - eff) * Math.tan(firstLatitude));
    var u2 = Math.atan((1 - eff) * Math.tan(secondLatitude));

    var cosineU1 = Math.cos(u1);
    var sineU1 = Math.sin(u1);
    var cosineU2 = Math.cos(u2);
    var sineU2 = Math.sin(u2);

    var cc = cosineU1 * cosineU2;
    var cs = cosineU1 * sineU2;
    var ss = sineU1 * sineU2;
    var sc = sineU1 * cosineU2;

    var lambda = l;
    var lambdaDot = CesiumMath.TWO_PI;

    var cosineLambda = Math.cos(lambda);
    var sineLambda = Math.sin(lambda);

    var sigma;
    var cosineSigma;
    var sineSigma;
    var cosineSquaredAlpha;
    var cosineTwiceSigmaMidpoint;

    do {
      cosineLambda = Math.cos(lambda);
      sineLambda = Math.sin(lambda);

      var temp = cs - sc * cosineLambda;
      sineSigma = Math.sqrt(
        cosineU2 * cosineU2 * sineLambda * sineLambda + temp * temp
      );
      cosineSigma = ss + cc * cosineLambda;

      sigma = Math.atan2(sineSigma, cosineSigma);

      var sineAlpha;

      if (sineSigma === 0.0) {
        sineAlpha = 0.0;
        cosineSquaredAlpha = 1.0;
      } else {
        sineAlpha = (cc * sineLambda) / sineSigma;
        cosineSquaredAlpha = 1.0 - sineAlpha * sineAlpha;
      }

      lambdaDot = lambda;

      cosineTwiceSigmaMidpoint = cosineSigma - (2.0 * ss) / cosineSquaredAlpha;

      if (isNaN(cosineTwiceSigmaMidpoint)) {
        cosineTwiceSigmaMidpoint = 0.0;
      }

      lambda =
        l +
        computeDeltaLambda(
          eff,
          sineAlpha,
          cosineSquaredAlpha,
          sigma,
          sineSigma,
          cosineSigma,
          cosineTwiceSigmaMidpoint
        );
    } while (Math.abs(lambda - lambdaDot) > CesiumMath.EPSILON12);

    var uSquared =
      (cosineSquaredAlpha * (major * major - minor * minor)) / (minor * minor);
    var A =
      1.0 +
      (uSquared *
        (4096.0 + uSquared * (uSquared * (320.0 - 175.0 * uSquared) - 768.0))) /
        16384.0;
    var B =
      (uSquared *
        (256.0 + uSquared * (uSquared * (74.0 - 47.0 * uSquared) - 128.0))) /
      1024.0;

    var cosineSquaredTwiceSigmaMidpoint =
      cosineTwiceSigmaMidpoint * cosineTwiceSigmaMidpoint;
    var deltaSigma =
      B *
      sineSigma *
      (cosineTwiceSigmaMidpoint +
        (B *
          (cosineSigma * (2.0 * cosineSquaredTwiceSigmaMidpoint - 1.0) -
            (B *
              cosineTwiceSigmaMidpoint *
              (4.0 * sineSigma * sineSigma - 3.0) *
              (4.0 * cosineSquaredTwiceSigmaMidpoint - 3.0)) /
              6.0)) /
          4.0);

    var distance = minor * A * (sigma - deltaSigma);

    var startHeading = Math.atan2(cosineU2 * sineLambda, cs - sc * cosineLambda);
    var endHeading = Math.atan2(cosineU1 * sineLambda, cs * cosineLambda - sc);

    ellipsoidGeodesic._distance = distance;
    ellipsoidGeodesic._startHeading = startHeading;
    ellipsoidGeodesic._endHeading = endHeading;
    ellipsoidGeodesic._uSquared = uSquared;
  }

  var scratchCart1$1 = new Cartesian3();
  var scratchCart2$1 = new Cartesian3();
  function computeProperties$1(ellipsoidGeodesic, start, end, ellipsoid) {
    var firstCartesian = Cartesian3.normalize(
      ellipsoid.cartographicToCartesian(start, scratchCart2$1),
      scratchCart1$1
    );
    var lastCartesian = Cartesian3.normalize(
      ellipsoid.cartographicToCartesian(end, scratchCart2$1),
      scratchCart2$1
    );

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals(
      "value",
      Math.abs(
        Math.abs(Cartesian3.angleBetween(firstCartesian, lastCartesian)) - Math.PI
      ),
      0.0125
    );
    //>>includeEnd('debug');

    vincentyInverseFormula(
      ellipsoidGeodesic,
      ellipsoid.maximumRadius,
      ellipsoid.minimumRadius,
      start.longitude,
      start.latitude,
      end.longitude,
      end.latitude
    );

    ellipsoidGeodesic._start = Cartographic.clone(
      start,
      ellipsoidGeodesic._start
    );
    ellipsoidGeodesic._end = Cartographic.clone(end, ellipsoidGeodesic._end);
    ellipsoidGeodesic._start.height = 0;
    ellipsoidGeodesic._end.height = 0;

    setConstants(ellipsoidGeodesic);
  }

  /**
   * Initializes a geodesic on the ellipsoid connecting the two provided planetodetic points.
   *
   * @alias EllipsoidGeodesic
   * @constructor
   *
   * @param {Cartographic} [start] The initial planetodetic point on the path.
   * @param {Cartographic} [end] The final planetodetic point on the path.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the geodesic lies.
   */
  function EllipsoidGeodesic(start, end, ellipsoid) {
    var e = defaultValue(ellipsoid, Ellipsoid.WGS84);
    this._ellipsoid = e;
    this._start = new Cartographic();
    this._end = new Cartographic();

    this._constants = {};
    this._startHeading = undefined;
    this._endHeading = undefined;
    this._distance = undefined;
    this._uSquared = undefined;

    if (defined(start) && defined(end)) {
      computeProperties$1(this, start, end, e);
    }
  }

  Object.defineProperties(EllipsoidGeodesic.prototype, {
    /**
     * Gets the ellipsoid.
     * @memberof EllipsoidGeodesic.prototype
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },

    /**
     * Gets the surface distance between the start and end point
     * @memberof EllipsoidGeodesic.prototype
     * @type {Number}
     * @readonly
     */
    surfaceDistance: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("distance", this._distance);
        //>>includeEnd('debug');

        return this._distance;
      },
    },

    /**
     * Gets the initial planetodetic point on the path.
     * @memberof EllipsoidGeodesic.prototype
     * @type {Cartographic}
     * @readonly
     */
    start: {
      get: function () {
        return this._start;
      },
    },

    /**
     * Gets the final planetodetic point on the path.
     * @memberof EllipsoidGeodesic.prototype
     * @type {Cartographic}
     * @readonly
     */
    end: {
      get: function () {
        return this._end;
      },
    },

    /**
     * Gets the heading at the initial point.
     * @memberof EllipsoidGeodesic.prototype
     * @type {Number}
     * @readonly
     */
    startHeading: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("distance", this._distance);
        //>>includeEnd('debug');

        return this._startHeading;
      },
    },

    /**
     * Gets the heading at the final point.
     * @memberof EllipsoidGeodesic.prototype
     * @type {Number}
     * @readonly
     */
    endHeading: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("distance", this._distance);
        //>>includeEnd('debug');

        return this._endHeading;
      },
    },
  });

  /**
   * Sets the start and end points of the geodesic
   *
   * @param {Cartographic} start The initial planetodetic point on the path.
   * @param {Cartographic} end The final planetodetic point on the path.
   */
  EllipsoidGeodesic.prototype.setEndPoints = function (start, end) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("start", start);
    Check.defined("end", end);
    //>>includeEnd('debug');

    computeProperties$1(this, start, end, this._ellipsoid);
  };

  /**
   * Provides the location of a point at the indicated portion along the geodesic.
   *
   * @param {Number} fraction The portion of the distance between the initial and final points.
   * @param {Cartographic} [result] The object in which to store the result.
   * @returns {Cartographic} The location of the point along the geodesic.
   */
  EllipsoidGeodesic.prototype.interpolateUsingFraction = function (
    fraction,
    result
  ) {
    return this.interpolateUsingSurfaceDistance(
      this._distance * fraction,
      result
    );
  };

  /**
   * Provides the location of a point at the indicated distance along the geodesic.
   *
   * @param {Number} distance The distance from the inital point to the point of interest along the geodesic
   * @param {Cartographic} [result] The object in which to store the result.
   * @returns {Cartographic} The location of the point along the geodesic.
   *
   * @exception {DeveloperError} start and end must be set before calling function interpolateUsingSurfaceDistance
   */
  EllipsoidGeodesic.prototype.interpolateUsingSurfaceDistance = function (
    distance,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("distance", this._distance);
    //>>includeEnd('debug');

    var constants = this._constants;

    var s = constants.distanceRatio + distance / constants.b;

    var cosine2S = Math.cos(2.0 * s);
    var cosine4S = Math.cos(4.0 * s);
    var cosine6S = Math.cos(6.0 * s);
    var sine2S = Math.sin(2.0 * s);
    var sine4S = Math.sin(4.0 * s);
    var sine6S = Math.sin(6.0 * s);
    var sine8S = Math.sin(8.0 * s);

    var s2 = s * s;
    var s3 = s * s2;

    var u8Over256 = constants.u8Over256;
    var u2Over4 = constants.u2Over4;
    var u6Over64 = constants.u6Over64;
    var u4Over16 = constants.u4Over16;
    var sigma =
      (2.0 * s3 * u8Over256 * cosine2S) / 3.0 +
      s *
        (1.0 -
          u2Over4 +
          (7.0 * u4Over16) / 4.0 -
          (15.0 * u6Over64) / 4.0 +
          (579.0 * u8Over256) / 64.0 -
          (u4Over16 - (15.0 * u6Over64) / 4.0 + (187.0 * u8Over256) / 16.0) *
            cosine2S -
          ((5.0 * u6Over64) / 4.0 - (115.0 * u8Over256) / 16.0) * cosine4S -
          (29.0 * u8Over256 * cosine6S) / 16.0) +
      (u2Over4 / 2.0 -
        u4Over16 +
        (71.0 * u6Over64) / 32.0 -
        (85.0 * u8Over256) / 16.0) *
        sine2S +
      ((5.0 * u4Over16) / 16.0 -
        (5.0 * u6Over64) / 4.0 +
        (383.0 * u8Over256) / 96.0) *
        sine4S -
      s2 *
        ((u6Over64 - (11.0 * u8Over256) / 2.0) * sine2S +
          (5.0 * u8Over256 * sine4S) / 2.0) +
      ((29.0 * u6Over64) / 96.0 - (29.0 * u8Over256) / 16.0) * sine6S +
      (539.0 * u8Over256 * sine8S) / 1536.0;

    var theta = Math.asin(Math.sin(sigma) * constants.cosineAlpha);
    var latitude = Math.atan((constants.a / constants.b) * Math.tan(theta));

    // Redefine in terms of relative argument of latitude.
    sigma = sigma - constants.sigma;

    var cosineTwiceSigmaMidpoint = Math.cos(2.0 * constants.sigma + sigma);

    var sineSigma = Math.sin(sigma);
    var cosineSigma = Math.cos(sigma);

    var cc = constants.cosineU * cosineSigma;
    var ss = constants.sineU * sineSigma;

    var lambda = Math.atan2(
      sineSigma * constants.sineHeading,
      cc - ss * constants.cosineHeading
    );

    var l =
      lambda -
      computeDeltaLambda(
        constants.f,
        constants.sineAlpha,
        constants.cosineSquaredAlpha,
        sigma,
        sineSigma,
        cosineSigma,
        cosineTwiceSigmaMidpoint
      );

    if (defined(result)) {
      result.longitude = this._start.longitude + l;
      result.latitude = latitude;
      result.height = 0.0;
      return result;
    }

    return new Cartographic(this._start.longitude + l, latitude, 0.0);
  };

  /**
   * @private
   */
  var PolylinePipeline = {};

  PolylinePipeline.numberOfPoints = function (p0, p1, minDistance) {
    var distance = Cartesian3.distance(p0, p1);
    return Math.ceil(distance / minDistance);
  };

  PolylinePipeline.numberOfPointsRhumbLine = function (p0, p1, granularity) {
    var radiansDistanceSquared =
      Math.pow(p0.longitude - p1.longitude, 2) +
      Math.pow(p0.latitude - p1.latitude, 2);

    return Math.max(
      1,
      Math.ceil(Math.sqrt(radiansDistanceSquared / (granularity * granularity)))
    );
  };

  var cartoScratch = new Cartographic();
  PolylinePipeline.extractHeights = function (positions, ellipsoid) {
    var length = positions.length;
    var heights = new Array(length);
    for (var i = 0; i < length; i++) {
      var p = positions[i];
      heights[i] = ellipsoid.cartesianToCartographic(p, cartoScratch).height;
    }
    return heights;
  };

  var wrapLongitudeInversMatrix = new Matrix4();
  var wrapLongitudeOrigin = new Cartesian3();
  var wrapLongitudeXZNormal = new Cartesian3();
  var wrapLongitudeXZPlane = new Plane(Cartesian3.UNIT_X, 0.0);
  var wrapLongitudeYZNormal = new Cartesian3();
  var wrapLongitudeYZPlane = new Plane(Cartesian3.UNIT_X, 0.0);
  var wrapLongitudeIntersection = new Cartesian3();
  var wrapLongitudeOffset = new Cartesian3();

  var subdivideHeightsScratchArray = [];

  function subdivideHeights(numPoints, h0, h1) {
    var heights = subdivideHeightsScratchArray;
    heights.length = numPoints;

    var i;
    if (h0 === h1) {
      for (i = 0; i < numPoints; i++) {
        heights[i] = h0;
      }
      return heights;
    }

    var dHeight = h1 - h0;
    var heightPerVertex = dHeight / numPoints;

    for (i = 0; i < numPoints; i++) {
      var h = h0 + i * heightPerVertex;
      heights[i] = h;
    }

    return heights;
  }

  var carto1 = new Cartographic();
  var carto2 = new Cartographic();
  var cartesian = new Cartesian3();
  var scaleFirst = new Cartesian3();
  var scaleLast = new Cartesian3();
  var ellipsoidGeodesic = new EllipsoidGeodesic();
  var ellipsoidRhumb = new EllipsoidRhumbLine();

  //Returns subdivided line scaled to ellipsoid surface starting at p1 and ending at p2.
  //Result includes p1, but not include p2.  This function is called for a sequence of line segments,
  //and this prevents duplication of end point.
  function generateCartesianArc(
    p0,
    p1,
    minDistance,
    ellipsoid,
    h0,
    h1,
    array,
    offset
  ) {
    var first = ellipsoid.scaleToGeodeticSurface(p0, scaleFirst);
    var last = ellipsoid.scaleToGeodeticSurface(p1, scaleLast);
    var numPoints = PolylinePipeline.numberOfPoints(p0, p1, minDistance);
    var start = ellipsoid.cartesianToCartographic(first, carto1);
    var end = ellipsoid.cartesianToCartographic(last, carto2);
    var heights = subdivideHeights(numPoints, h0, h1);

    ellipsoidGeodesic.setEndPoints(start, end);
    var surfaceDistanceBetweenPoints =
      ellipsoidGeodesic.surfaceDistance / numPoints;

    var index = offset;
    start.height = h0;
    var cart = ellipsoid.cartographicToCartesian(start, cartesian);
    Cartesian3.pack(cart, array, index);
    index += 3;

    for (var i = 1; i < numPoints; i++) {
      var carto = ellipsoidGeodesic.interpolateUsingSurfaceDistance(
        i * surfaceDistanceBetweenPoints,
        carto2
      );
      carto.height = heights[i];
      cart = ellipsoid.cartographicToCartesian(carto, cartesian);
      Cartesian3.pack(cart, array, index);
      index += 3;
    }

    return index;
  }

  //Returns subdivided line scaled to ellipsoid surface starting at p1 and ending at p2.
  //Result includes p1, but not include p2.  This function is called for a sequence of line segments,
  //and this prevents duplication of end point.
  function generateCartesianRhumbArc(
    p0,
    p1,
    granularity,
    ellipsoid,
    h0,
    h1,
    array,
    offset
  ) {
    var start = ellipsoid.cartesianToCartographic(p0, carto1);
    var end = ellipsoid.cartesianToCartographic(p1, carto2);
    var numPoints = PolylinePipeline.numberOfPointsRhumbLine(
      start,
      end,
      granularity
    );
    start.height = 0.0;
    end.height = 0.0;
    var heights = subdivideHeights(numPoints, h0, h1);

    if (!ellipsoidRhumb.ellipsoid.equals(ellipsoid)) {
      ellipsoidRhumb = new EllipsoidRhumbLine(undefined, undefined, ellipsoid);
    }
    ellipsoidRhumb.setEndPoints(start, end);
    var surfaceDistanceBetweenPoints = ellipsoidRhumb.surfaceDistance / numPoints;

    var index = offset;
    start.height = h0;
    var cart = ellipsoid.cartographicToCartesian(start, cartesian);
    Cartesian3.pack(cart, array, index);
    index += 3;

    for (var i = 1; i < numPoints; i++) {
      var carto = ellipsoidRhumb.interpolateUsingSurfaceDistance(
        i * surfaceDistanceBetweenPoints,
        carto2
      );
      carto.height = heights[i];
      cart = ellipsoid.cartographicToCartesian(carto, cartesian);
      Cartesian3.pack(cart, array, index);
      index += 3;
    }

    return index;
  }

  /**
   * Breaks a {@link Polyline} into segments such that it does not cross the &plusmn;180 degree meridian of an ellipsoid.
   *
   * @param {Cartesian3[]} positions The polyline's Cartesian positions.
   * @param {Matrix4} [modelMatrix=Matrix4.IDENTITY] The polyline's model matrix. Assumed to be an affine
   * transformation matrix, where the upper left 3x3 elements are a rotation matrix, and
   * the upper three elements in the fourth column are the translation.  The bottom row is assumed to be [0, 0, 0, 1].
   * The matrix is not verified to be in the proper form.
   * @returns {Object} An object with a <code>positions</code> property that is an array of positions and a
   * <code>segments</code> property.
   *
   *
   * @example
   * var polylines = new Cesium.PolylineCollection();
   * var polyline = polylines.add(...);
   * var positions = polyline.positions;
   * var modelMatrix = polylines.modelMatrix;
   * var segments = Cesium.PolylinePipeline.wrapLongitude(positions, modelMatrix);
   *
   * @see PolygonPipeline.wrapLongitude
   * @see Polyline
   * @see PolylineCollection
   */
  PolylinePipeline.wrapLongitude = function (positions, modelMatrix) {
    var cartesians = [];
    var segments = [];

    if (defined(positions) && positions.length > 0) {
      modelMatrix = defaultValue(modelMatrix, Matrix4.IDENTITY);
      var inverseModelMatrix = Matrix4.inverseTransformation(
        modelMatrix,
        wrapLongitudeInversMatrix
      );

      var origin = Matrix4.multiplyByPoint(
        inverseModelMatrix,
        Cartesian3.ZERO,
        wrapLongitudeOrigin
      );
      var xzNormal = Cartesian3.normalize(
        Matrix4.multiplyByPointAsVector(
          inverseModelMatrix,
          Cartesian3.UNIT_Y,
          wrapLongitudeXZNormal
        ),
        wrapLongitudeXZNormal
      );
      var xzPlane = Plane.fromPointNormal(origin, xzNormal, wrapLongitudeXZPlane);
      var yzNormal = Cartesian3.normalize(
        Matrix4.multiplyByPointAsVector(
          inverseModelMatrix,
          Cartesian3.UNIT_X,
          wrapLongitudeYZNormal
        ),
        wrapLongitudeYZNormal
      );
      var yzPlane = Plane.fromPointNormal(origin, yzNormal, wrapLongitudeYZPlane);

      var count = 1;
      cartesians.push(Cartesian3.clone(positions[0]));
      var prev = cartesians[0];

      var length = positions.length;
      for (var i = 1; i < length; ++i) {
        var cur = positions[i];

        // intersects the IDL if either endpoint is on the negative side of the yz-plane
        if (
          Plane.getPointDistance(yzPlane, prev) < 0.0 ||
          Plane.getPointDistance(yzPlane, cur) < 0.0
        ) {
          // and intersects the xz-plane
          var intersection = IntersectionTests.lineSegmentPlane(
            prev,
            cur,
            xzPlane,
            wrapLongitudeIntersection
          );
          if (defined(intersection)) {
            // move point on the xz-plane slightly away from the plane
            var offset = Cartesian3.multiplyByScalar(
              xzNormal,
              5.0e-9,
              wrapLongitudeOffset
            );
            if (Plane.getPointDistance(xzPlane, prev) < 0.0) {
              Cartesian3.negate(offset, offset);
            }

            cartesians.push(
              Cartesian3.add(intersection, offset, new Cartesian3())
            );
            segments.push(count + 1);

            Cartesian3.negate(offset, offset);
            cartesians.push(
              Cartesian3.add(intersection, offset, new Cartesian3())
            );
            count = 1;
          }
        }

        cartesians.push(Cartesian3.clone(positions[i]));
        count++;

        prev = cur;
      }

      segments.push(count);
    }

    return {
      positions: cartesians,
      lengths: segments,
    };
  };

  /**
   * Subdivides polyline and raises all points to the specified height.  Returns an array of numbers to represent the positions.
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions The array of type {Cartesian3} representing positions.
   * @param {Number|Number[]} [options.height=0.0] A number or array of numbers representing the heights of each position.
   * @param {Number} [options.granularity = CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the positions lie.
   * @returns {Number[]} A new array of positions of type {Number} that have been subdivided and raised to the surface of the ellipsoid.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArray([
   *   -105.0, 40.0,
   *   -100.0, 38.0,
   *   -105.0, 35.0,
   *   -100.0, 32.0
   * ]);
   * var surfacePositions = Cesium.PolylinePipeline.generateArc({
   *   positons: positions
   * });
   */
  PolylinePipeline.generateArc = function (options) {
    if (!defined(options)) {
      options = {};
    }
    var positions = options.positions;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions)) {
      throw new DeveloperError("options.positions is required.");
    }
    //>>includeEnd('debug');

    var length = positions.length;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var height = defaultValue(options.height, 0);
    var hasHeightArray = Array.isArray(height);

    if (length < 1) {
      return [];
    } else if (length === 1) {
      var p = ellipsoid.scaleToGeodeticSurface(positions[0], scaleFirst);
      height = hasHeightArray ? height[0] : height;
      if (height !== 0) {
        var n = ellipsoid.geodeticSurfaceNormal(p, cartesian);
        Cartesian3.multiplyByScalar(n, height, n);
        Cartesian3.add(p, n, p);
      }

      return [p.x, p.y, p.z];
    }

    var minDistance = options.minDistance;
    if (!defined(minDistance)) {
      var granularity = defaultValue(
        options.granularity,
        CesiumMath.RADIANS_PER_DEGREE
      );
      minDistance = CesiumMath.chordLength(granularity, ellipsoid.maximumRadius);
    }

    var numPoints = 0;
    var i;

    for (i = 0; i < length - 1; i++) {
      numPoints += PolylinePipeline.numberOfPoints(
        positions[i],
        positions[i + 1],
        minDistance
      );
    }

    var arrayLength = (numPoints + 1) * 3;
    var newPositions = new Array(arrayLength);
    var offset = 0;

    for (i = 0; i < length - 1; i++) {
      var p0 = positions[i];
      var p1 = positions[i + 1];

      var h0 = hasHeightArray ? height[i] : height;
      var h1 = hasHeightArray ? height[i + 1] : height;

      offset = generateCartesianArc(
        p0,
        p1,
        minDistance,
        ellipsoid,
        h0,
        h1,
        newPositions,
        offset
      );
    }

    subdivideHeightsScratchArray.length = 0;

    var lastPoint = positions[length - 1];
    var carto = ellipsoid.cartesianToCartographic(lastPoint, carto1);
    carto.height = hasHeightArray ? height[length - 1] : height;
    var cart = ellipsoid.cartographicToCartesian(carto, cartesian);
    Cartesian3.pack(cart, newPositions, arrayLength - 3);

    return newPositions;
  };

  var scratchCartographic0$1 = new Cartographic();
  var scratchCartographic1$1 = new Cartographic();

  /**
   * Subdivides polyline and raises all points to the specified height using Rhumb lines.  Returns an array of numbers to represent the positions.
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions The array of type {Cartesian3} representing positions.
   * @param {Number|Number[]} [options.height=0.0] A number or array of numbers representing the heights of each position.
   * @param {Number} [options.granularity = CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the positions lie.
   * @returns {Number[]} A new array of positions of type {Number} that have been subdivided and raised to the surface of the ellipsoid.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArray([
   *   -105.0, 40.0,
   *   -100.0, 38.0,
   *   -105.0, 35.0,
   *   -100.0, 32.0
   * ]);
   * var surfacePositions = Cesium.PolylinePipeline.generateRhumbArc({
   *   positons: positions
   * });
   */
  PolylinePipeline.generateRhumbArc = function (options) {
    if (!defined(options)) {
      options = {};
    }
    var positions = options.positions;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions)) {
      throw new DeveloperError("options.positions is required.");
    }
    //>>includeEnd('debug');

    var length = positions.length;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var height = defaultValue(options.height, 0);
    var hasHeightArray = Array.isArray(height);

    if (length < 1) {
      return [];
    } else if (length === 1) {
      var p = ellipsoid.scaleToGeodeticSurface(positions[0], scaleFirst);
      height = hasHeightArray ? height[0] : height;
      if (height !== 0) {
        var n = ellipsoid.geodeticSurfaceNormal(p, cartesian);
        Cartesian3.multiplyByScalar(n, height, n);
        Cartesian3.add(p, n, p);
      }

      return [p.x, p.y, p.z];
    }

    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );

    var numPoints = 0;
    var i;

    var c0 = ellipsoid.cartesianToCartographic(
      positions[0],
      scratchCartographic0$1
    );
    var c1;
    for (i = 0; i < length - 1; i++) {
      c1 = ellipsoid.cartesianToCartographic(
        positions[i + 1],
        scratchCartographic1$1
      );
      numPoints += PolylinePipeline.numberOfPointsRhumbLine(c0, c1, granularity);
      c0 = Cartographic.clone(c1, scratchCartographic0$1);
    }

    var arrayLength = (numPoints + 1) * 3;
    var newPositions = new Array(arrayLength);
    var offset = 0;

    for (i = 0; i < length - 1; i++) {
      var p0 = positions[i];
      var p1 = positions[i + 1];

      var h0 = hasHeightArray ? height[i] : height;
      var h1 = hasHeightArray ? height[i + 1] : height;

      offset = generateCartesianRhumbArc(
        p0,
        p1,
        granularity,
        ellipsoid,
        h0,
        h1,
        newPositions,
        offset
      );
    }

    subdivideHeightsScratchArray.length = 0;

    var lastPoint = positions[length - 1];
    var carto = ellipsoid.cartesianToCartographic(lastPoint, carto1);
    carto.height = hasHeightArray ? height[length - 1] : height;
    var cart = ellipsoid.cartographicToCartesian(carto, cartesian);
    Cartesian3.pack(cart, newPositions, arrayLength - 3);

    return newPositions;
  };

  /**
   * Subdivides polyline and raises all points to the specified height. Returns an array of new {Cartesian3} positions.
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions The array of type {Cartesian3} representing positions.
   * @param {Number|Number[]} [options.height=0.0] A number or array of numbers representing the heights of each position.
   * @param {Number} [options.granularity = CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the positions lie.
   * @returns {Cartesian3[]} A new array of cartesian3 positions that have been subdivided and raised to the surface of the ellipsoid.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArray([
   *   -105.0, 40.0,
   *   -100.0, 38.0,
   *   -105.0, 35.0,
   *   -100.0, 32.0
   * ]);
   * var surfacePositions = Cesium.PolylinePipeline.generateCartesianArc({
   *   positons: positions
   * });
   */
  PolylinePipeline.generateCartesianArc = function (options) {
    var numberArray = PolylinePipeline.generateArc(options);
    var size = numberArray.length / 3;
    var newPositions = new Array(size);
    for (var i = 0; i < size; i++) {
      newPositions[i] = Cartesian3.unpack(numberArray, i * 3);
    }
    return newPositions;
  };

  /**
   * Subdivides polyline and raises all points to the specified height using Rhumb Lines. Returns an array of new {Cartesian3} positions.
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions The array of type {Cartesian3} representing positions.
   * @param {Number|Number[]} [options.height=0.0] A number or array of numbers representing the heights of each position.
   * @param {Number} [options.granularity = CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the positions lie.
   * @returns {Cartesian3[]} A new array of cartesian3 positions that have been subdivided and raised to the surface of the ellipsoid.
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArray([
   *   -105.0, 40.0,
   *   -100.0, 38.0,
   *   -105.0, 35.0,
   *   -100.0, 32.0
   * ]);
   * var surfacePositions = Cesium.PolylinePipeline.generateCartesianRhumbArc({
   *   positons: positions
   * });
   */
  PolylinePipeline.generateCartesianRhumbArc = function (options) {
    var numberArray = PolylinePipeline.generateRhumbArc(options);
    var size = numberArray.length / 3;
    var newPositions = new Array(size);
    for (var i = 0; i < size; i++) {
      newPositions[i] = Cartesian3.unpack(numberArray, i * 3);
    }
    return newPositions;
  };

  var scratch2Array = [new Cartesian3(), new Cartesian3()];
  var scratchCartesian1$5 = new Cartesian3();
  var scratchCartesian2$5 = new Cartesian3();
  var scratchCartesian3$6 = new Cartesian3();
  var scratchCartesian4$2 = new Cartesian3();
  var scratchCartesian5$1 = new Cartesian3();
  var scratchCartesian6$1 = new Cartesian3();
  var scratchCartesian7 = new Cartesian3();
  var scratchCartesian8 = new Cartesian3();
  var scratchCartesian9 = new Cartesian3();

  var scratch1 = new Cartesian3();
  var scratch2 = new Cartesian3();

  /**
   * @private
   */
  var PolylineVolumeGeometryLibrary = {};

  var cartographic = new Cartographic();
  function scaleToSurface(positions, ellipsoid) {
    var heights = new Array(positions.length);
    for (var i = 0; i < positions.length; i++) {
      var pos = positions[i];
      cartographic = ellipsoid.cartesianToCartographic(pos, cartographic);
      heights[i] = cartographic.height;
      positions[i] = ellipsoid.scaleToGeodeticSurface(pos, pos);
    }
    return heights;
  }

  function subdivideHeights$1(points, h0, h1, granularity) {
    var p0 = points[0];
    var p1 = points[1];
    var angleBetween = Cartesian3.angleBetween(p0, p1);
    var numPoints = Math.ceil(angleBetween / granularity);
    var heights = new Array(numPoints);
    var i;
    if (h0 === h1) {
      for (i = 0; i < numPoints; i++) {
        heights[i] = h0;
      }
      heights.push(h1);
      return heights;
    }

    var dHeight = h1 - h0;
    var heightPerVertex = dHeight / numPoints;

    for (i = 1; i < numPoints; i++) {
      var h = h0 + i * heightPerVertex;
      heights[i] = h;
    }

    heights[0] = h0;
    heights.push(h1);
    return heights;
  }

  var nextScratch = new Cartesian3();
  var prevScratch = new Cartesian3();

  function computeRotationAngle(start, end, position, ellipsoid) {
    var tangentPlane = new EllipsoidTangentPlane(position, ellipsoid);
    var next = tangentPlane.projectPointOntoPlane(
      Cartesian3.add(position, start, nextScratch),
      nextScratch
    );
    var prev = tangentPlane.projectPointOntoPlane(
      Cartesian3.add(position, end, prevScratch),
      prevScratch
    );
    var angle = Cartesian2.angleBetween(next, prev);

    return prev.x * next.y - prev.y * next.x >= 0.0 ? -angle : angle;
  }

  var negativeX = new Cartesian3(-1, 0, 0);
  var transform = new Matrix4();
  var translation = new Matrix4();
  var rotationZ = new Matrix3();
  var scaleMatrix = Matrix3.IDENTITY.clone();
  var westScratch$1 = new Cartesian3();
  var finalPosScratch = new Cartesian4();
  var heightCartesian = new Cartesian3();
  function addPosition(
    center,
    left,
    shape,
    finalPositions,
    ellipsoid,
    height,
    xScalar,
    repeat
  ) {
    var west = westScratch$1;
    var finalPosition = finalPosScratch;
    transform = Transforms.eastNorthUpToFixedFrame(center, ellipsoid, transform);

    west = Matrix4.multiplyByPointAsVector(transform, negativeX, west);
    west = Cartesian3.normalize(west, west);
    var angle = computeRotationAngle(west, left, center, ellipsoid);
    rotationZ = Matrix3.fromRotationZ(angle, rotationZ);

    heightCartesian.z = height;
    transform = Matrix4.multiplyTransformation(
      transform,
      Matrix4.fromRotationTranslation(rotationZ, heightCartesian, translation),
      transform
    );
    var scale = scaleMatrix;
    scale[0] = xScalar;

    for (var j = 0; j < repeat; j++) {
      for (var i = 0; i < shape.length; i += 3) {
        finalPosition = Cartesian3.fromArray(shape, i, finalPosition);
        finalPosition = Matrix3.multiplyByVector(
          scale,
          finalPosition,
          finalPosition
        );
        finalPosition = Matrix4.multiplyByPoint(
          transform,
          finalPosition,
          finalPosition
        );
        finalPositions.push(finalPosition.x, finalPosition.y, finalPosition.z);
      }
    }

    return finalPositions;
  }

  var centerScratch$1 = new Cartesian3();
  function addPositions(
    centers,
    left,
    shape,
    finalPositions,
    ellipsoid,
    heights,
    xScalar
  ) {
    for (var i = 0; i < centers.length; i += 3) {
      var center = Cartesian3.fromArray(centers, i, centerScratch$1);
      finalPositions = addPosition(
        center,
        left,
        shape,
        finalPositions,
        ellipsoid,
        heights[i / 3],
        xScalar,
        1
      );
    }
    return finalPositions;
  }

  function convertShapeTo3DDuplicate(shape2D, boundingRectangle) {
    //orientate 2D shape to XZ plane center at (0, 0, 0), duplicate points
    var length = shape2D.length;
    var shape = new Array(length * 6);
    var index = 0;
    var xOffset = boundingRectangle.x + boundingRectangle.width / 2;
    var yOffset = boundingRectangle.y + boundingRectangle.height / 2;

    var point = shape2D[0];
    shape[index++] = point.x - xOffset;
    shape[index++] = 0.0;
    shape[index++] = point.y - yOffset;
    for (var i = 1; i < length; i++) {
      point = shape2D[i];
      var x = point.x - xOffset;
      var z = point.y - yOffset;
      shape[index++] = x;
      shape[index++] = 0.0;
      shape[index++] = z;

      shape[index++] = x;
      shape[index++] = 0.0;
      shape[index++] = z;
    }
    point = shape2D[0];
    shape[index++] = point.x - xOffset;
    shape[index++] = 0.0;
    shape[index++] = point.y - yOffset;

    return shape;
  }

  function convertShapeTo3D(shape2D, boundingRectangle) {
    //orientate 2D shape to XZ plane center at (0, 0, 0)
    var length = shape2D.length;
    var shape = new Array(length * 3);
    var index = 0;
    var xOffset = boundingRectangle.x + boundingRectangle.width / 2;
    var yOffset = boundingRectangle.y + boundingRectangle.height / 2;

    for (var i = 0; i < length; i++) {
      shape[index++] = shape2D[i].x - xOffset;
      shape[index++] = 0;
      shape[index++] = shape2D[i].y - yOffset;
    }

    return shape;
  }

  var quaterion = new Quaternion();
  var startPointScratch = new Cartesian3();
  var rotMatrix = new Matrix3();
  function computeRoundCorner(
    pivot,
    startPoint,
    endPoint,
    cornerType,
    leftIsOutside,
    ellipsoid,
    finalPositions,
    shape,
    height,
    duplicatePoints
  ) {
    var angle = Cartesian3.angleBetween(
      Cartesian3.subtract(startPoint, pivot, scratch1),
      Cartesian3.subtract(endPoint, pivot, scratch2)
    );
    var granularity =
      cornerType === CornerType$1.BEVELED
        ? 0
        : Math.ceil(angle / CesiumMath.toRadians(5));

    var m;
    if (leftIsOutside) {
      m = Matrix3.fromQuaternion(
        Quaternion.fromAxisAngle(
          Cartesian3.negate(pivot, scratch1),
          angle / (granularity + 1),
          quaterion
        ),
        rotMatrix
      );
    } else {
      m = Matrix3.fromQuaternion(
        Quaternion.fromAxisAngle(pivot, angle / (granularity + 1), quaterion),
        rotMatrix
      );
    }

    var left;
    var surfacePoint;
    startPoint = Cartesian3.clone(startPoint, startPointScratch);
    if (granularity > 0) {
      var repeat = duplicatePoints ? 2 : 1;
      for (var i = 0; i < granularity; i++) {
        startPoint = Matrix3.multiplyByVector(m, startPoint, startPoint);
        left = Cartesian3.subtract(startPoint, pivot, scratch1);
        left = Cartesian3.normalize(left, left);
        if (!leftIsOutside) {
          left = Cartesian3.negate(left, left);
        }
        surfacePoint = ellipsoid.scaleToGeodeticSurface(startPoint, scratch2);
        finalPositions = addPosition(
          surfacePoint,
          left,
          shape,
          finalPositions,
          ellipsoid,
          height,
          1,
          repeat
        );
      }
    } else {
      left = Cartesian3.subtract(startPoint, pivot, scratch1);
      left = Cartesian3.normalize(left, left);
      if (!leftIsOutside) {
        left = Cartesian3.negate(left, left);
      }
      surfacePoint = ellipsoid.scaleToGeodeticSurface(startPoint, scratch2);
      finalPositions = addPosition(
        surfacePoint,
        left,
        shape,
        finalPositions,
        ellipsoid,
        height,
        1,
        1
      );

      endPoint = Cartesian3.clone(endPoint, startPointScratch);
      left = Cartesian3.subtract(endPoint, pivot, scratch1);
      left = Cartesian3.normalize(left, left);
      if (!leftIsOutside) {
        left = Cartesian3.negate(left, left);
      }
      surfacePoint = ellipsoid.scaleToGeodeticSurface(endPoint, scratch2);
      finalPositions = addPosition(
        surfacePoint,
        left,
        shape,
        finalPositions,
        ellipsoid,
        height,
        1,
        1
      );
    }

    return finalPositions;
  }

  PolylineVolumeGeometryLibrary.removeDuplicatesFromShape = function (
    shapePositions
  ) {
    var length = shapePositions.length;
    var cleanedPositions = [];
    for (var i0 = length - 1, i1 = 0; i1 < length; i0 = i1++) {
      var v0 = shapePositions[i0];
      var v1 = shapePositions[i1];

      if (!Cartesian2.equals(v0, v1)) {
        cleanedPositions.push(v1); // Shallow copy!
      }
    }

    return cleanedPositions;
  };

  PolylineVolumeGeometryLibrary.angleIsGreaterThanPi = function (
    forward,
    backward,
    position,
    ellipsoid
  ) {
    var tangentPlane = new EllipsoidTangentPlane(position, ellipsoid);
    var next = tangentPlane.projectPointOntoPlane(
      Cartesian3.add(position, forward, nextScratch),
      nextScratch
    );
    var prev = tangentPlane.projectPointOntoPlane(
      Cartesian3.add(position, backward, prevScratch),
      prevScratch
    );

    return prev.x * next.y - prev.y * next.x >= 0.0;
  };

  var scratchForwardProjection = new Cartesian3();
  var scratchBackwardProjection = new Cartesian3();

  PolylineVolumeGeometryLibrary.computePositions = function (
    positions,
    shape2D,
    boundingRectangle,
    geometry,
    duplicatePoints
  ) {
    var ellipsoid = geometry._ellipsoid;
    var heights = scaleToSurface(positions, ellipsoid);
    var granularity = geometry._granularity;
    var cornerType = geometry._cornerType;
    var shapeForSides = duplicatePoints
      ? convertShapeTo3DDuplicate(shape2D, boundingRectangle)
      : convertShapeTo3D(shape2D, boundingRectangle);
    var shapeForEnds = duplicatePoints
      ? convertShapeTo3D(shape2D, boundingRectangle)
      : undefined;
    var heightOffset = boundingRectangle.height / 2;
    var width = boundingRectangle.width / 2;
    var length = positions.length;
    var finalPositions = [];
    var ends = duplicatePoints ? [] : undefined;

    var forward = scratchCartesian1$5;
    var backward = scratchCartesian2$5;
    var cornerDirection = scratchCartesian3$6;
    var surfaceNormal = scratchCartesian4$2;
    var pivot = scratchCartesian5$1;
    var start = scratchCartesian6$1;
    var end = scratchCartesian7;
    var left = scratchCartesian8;
    var previousPosition = scratchCartesian9;

    var position = positions[0];
    var nextPosition = positions[1];
    surfaceNormal = ellipsoid.geodeticSurfaceNormal(position, surfaceNormal);
    forward = Cartesian3.subtract(nextPosition, position, forward);
    forward = Cartesian3.normalize(forward, forward);
    left = Cartesian3.cross(surfaceNormal, forward, left);
    left = Cartesian3.normalize(left, left);
    var h0 = heights[0];
    var h1 = heights[1];
    if (duplicatePoints) {
      ends = addPosition(
        position,
        left,
        shapeForEnds,
        ends,
        ellipsoid,
        h0 + heightOffset,
        1,
        1
      );
    }
    previousPosition = Cartesian3.clone(position, previousPosition);
    position = nextPosition;
    backward = Cartesian3.negate(forward, backward);
    var subdividedHeights;
    var subdividedPositions;
    for (var i = 1; i < length - 1; i++) {
      var repeat = duplicatePoints ? 2 : 1;
      nextPosition = positions[i + 1];
      forward = Cartesian3.subtract(nextPosition, position, forward);
      forward = Cartesian3.normalize(forward, forward);
      cornerDirection = Cartesian3.add(forward, backward, cornerDirection);
      cornerDirection = Cartesian3.normalize(cornerDirection, cornerDirection);
      surfaceNormal = ellipsoid.geodeticSurfaceNormal(position, surfaceNormal);

      var forwardProjection = Cartesian3.multiplyByScalar(
        surfaceNormal,
        Cartesian3.dot(forward, surfaceNormal),
        scratchForwardProjection
      );
      Cartesian3.subtract(forward, forwardProjection, forwardProjection);
      Cartesian3.normalize(forwardProjection, forwardProjection);

      var backwardProjection = Cartesian3.multiplyByScalar(
        surfaceNormal,
        Cartesian3.dot(backward, surfaceNormal),
        scratchBackwardProjection
      );
      Cartesian3.subtract(backward, backwardProjection, backwardProjection);
      Cartesian3.normalize(backwardProjection, backwardProjection);

      var doCorner = !CesiumMath.equalsEpsilon(
        Math.abs(Cartesian3.dot(forwardProjection, backwardProjection)),
        1.0,
        CesiumMath.EPSILON7
      );

      if (doCorner) {
        cornerDirection = Cartesian3.cross(
          cornerDirection,
          surfaceNormal,
          cornerDirection
        );
        cornerDirection = Cartesian3.cross(
          surfaceNormal,
          cornerDirection,
          cornerDirection
        );
        cornerDirection = Cartesian3.normalize(cornerDirection, cornerDirection);
        var scalar =
          1 /
          Math.max(
            0.25,
            Cartesian3.magnitude(
              Cartesian3.cross(cornerDirection, backward, scratch1)
            )
          );
        var leftIsOutside = PolylineVolumeGeometryLibrary.angleIsGreaterThanPi(
          forward,
          backward,
          position,
          ellipsoid
        );
        if (leftIsOutside) {
          pivot = Cartesian3.add(
            position,
            Cartesian3.multiplyByScalar(
              cornerDirection,
              scalar * width,
              cornerDirection
            ),
            pivot
          );
          start = Cartesian3.add(
            pivot,
            Cartesian3.multiplyByScalar(left, width, start),
            start
          );
          scratch2Array[0] = Cartesian3.clone(previousPosition, scratch2Array[0]);
          scratch2Array[1] = Cartesian3.clone(start, scratch2Array[1]);
          subdividedHeights = subdivideHeights$1(
            scratch2Array,
            h0 + heightOffset,
            h1 + heightOffset,
            granularity
          );
          subdividedPositions = PolylinePipeline.generateArc({
            positions: scratch2Array,
            granularity: granularity,
            ellipsoid: ellipsoid,
          });
          finalPositions = addPositions(
            subdividedPositions,
            left,
            shapeForSides,
            finalPositions,
            ellipsoid,
            subdividedHeights,
            1
          );
          left = Cartesian3.cross(surfaceNormal, forward, left);
          left = Cartesian3.normalize(left, left);
          end = Cartesian3.add(
            pivot,
            Cartesian3.multiplyByScalar(left, width, end),
            end
          );
          if (
            cornerType === CornerType$1.ROUNDED ||
            cornerType === CornerType$1.BEVELED
          ) {
            computeRoundCorner(
              pivot,
              start,
              end,
              cornerType,
              leftIsOutside,
              ellipsoid,
              finalPositions,
              shapeForSides,
              h1 + heightOffset,
              duplicatePoints
            );
          } else {
            cornerDirection = Cartesian3.negate(cornerDirection, cornerDirection);
            finalPositions = addPosition(
              position,
              cornerDirection,
              shapeForSides,
              finalPositions,
              ellipsoid,
              h1 + heightOffset,
              scalar,
              repeat
            );
          }
          previousPosition = Cartesian3.clone(end, previousPosition);
        } else {
          pivot = Cartesian3.add(
            position,
            Cartesian3.multiplyByScalar(
              cornerDirection,
              scalar * width,
              cornerDirection
            ),
            pivot
          );
          start = Cartesian3.add(
            pivot,
            Cartesian3.multiplyByScalar(left, -width, start),
            start
          );
          scratch2Array[0] = Cartesian3.clone(previousPosition, scratch2Array[0]);
          scratch2Array[1] = Cartesian3.clone(start, scratch2Array[1]);
          subdividedHeights = subdivideHeights$1(
            scratch2Array,
            h0 + heightOffset,
            h1 + heightOffset,
            granularity
          );
          subdividedPositions = PolylinePipeline.generateArc({
            positions: scratch2Array,
            granularity: granularity,
            ellipsoid: ellipsoid,
          });
          finalPositions = addPositions(
            subdividedPositions,
            left,
            shapeForSides,
            finalPositions,
            ellipsoid,
            subdividedHeights,
            1
          );
          left = Cartesian3.cross(surfaceNormal, forward, left);
          left = Cartesian3.normalize(left, left);
          end = Cartesian3.add(
            pivot,
            Cartesian3.multiplyByScalar(left, -width, end),
            end
          );
          if (
            cornerType === CornerType$1.ROUNDED ||
            cornerType === CornerType$1.BEVELED
          ) {
            computeRoundCorner(
              pivot,
              start,
              end,
              cornerType,
              leftIsOutside,
              ellipsoid,
              finalPositions,
              shapeForSides,
              h1 + heightOffset,
              duplicatePoints
            );
          } else {
            finalPositions = addPosition(
              position,
              cornerDirection,
              shapeForSides,
              finalPositions,
              ellipsoid,
              h1 + heightOffset,
              scalar,
              repeat
            );
          }
          previousPosition = Cartesian3.clone(end, previousPosition);
        }
        backward = Cartesian3.negate(forward, backward);
      } else {
        finalPositions = addPosition(
          previousPosition,
          left,
          shapeForSides,
          finalPositions,
          ellipsoid,
          h0 + heightOffset,
          1,
          1
        );
        previousPosition = position;
      }
      h0 = h1;
      h1 = heights[i + 1];
      position = nextPosition;
    }

    scratch2Array[0] = Cartesian3.clone(previousPosition, scratch2Array[0]);
    scratch2Array[1] = Cartesian3.clone(position, scratch2Array[1]);
    subdividedHeights = subdivideHeights$1(
      scratch2Array,
      h0 + heightOffset,
      h1 + heightOffset,
      granularity
    );
    subdividedPositions = PolylinePipeline.generateArc({
      positions: scratch2Array,
      granularity: granularity,
      ellipsoid: ellipsoid,
    });
    finalPositions = addPositions(
      subdividedPositions,
      left,
      shapeForSides,
      finalPositions,
      ellipsoid,
      subdividedHeights,
      1
    );
    if (duplicatePoints) {
      ends = addPosition(
        position,
        left,
        shapeForEnds,
        ends,
        ellipsoid,
        h1 + heightOffset,
        1,
        1
      );
    }

    length = finalPositions.length;
    var posLength = duplicatePoints ? length + ends.length : length;
    var combinedPositions = new Float64Array(posLength);
    combinedPositions.set(finalPositions);
    if (duplicatePoints) {
      combinedPositions.set(ends, length);
    }

    return combinedPositions;
  };

  /**
   * @private
   */
  var CorridorGeometryLibrary = {};

  var scratch1$1 = new Cartesian3();
  var scratch2$1 = new Cartesian3();
  var scratch3 = new Cartesian3();
  var scratch4 = new Cartesian3();

  var scaleArray2 = [new Cartesian3(), new Cartesian3()];

  var cartesian1 = new Cartesian3();
  var cartesian2 = new Cartesian3();
  var cartesian3 = new Cartesian3();
  var cartesian4 = new Cartesian3();
  var cartesian5 = new Cartesian3();
  var cartesian6 = new Cartesian3();
  var cartesian7 = new Cartesian3();
  var cartesian8 = new Cartesian3();
  var cartesian9 = new Cartesian3();
  var cartesian10 = new Cartesian3();

  var quaterion$1 = new Quaternion();
  var rotMatrix$1 = new Matrix3();
  function computeRoundCorner$1(
    cornerPoint,
    startPoint,
    endPoint,
    cornerType,
    leftIsOutside
  ) {
    var angle = Cartesian3.angleBetween(
      Cartesian3.subtract(startPoint, cornerPoint, scratch1$1),
      Cartesian3.subtract(endPoint, cornerPoint, scratch2$1)
    );
    var granularity =
      cornerType === CornerType$1.BEVELED
        ? 1
        : Math.ceil(angle / CesiumMath.toRadians(5)) + 1;

    var size = granularity * 3;
    var array = new Array(size);

    array[size - 3] = endPoint.x;
    array[size - 2] = endPoint.y;
    array[size - 1] = endPoint.z;

    var m;
    if (leftIsOutside) {
      m = Matrix3.fromQuaternion(
        Quaternion.fromAxisAngle(
          Cartesian3.negate(cornerPoint, scratch1$1),
          angle / granularity,
          quaterion$1
        ),
        rotMatrix$1
      );
    } else {
      m = Matrix3.fromQuaternion(
        Quaternion.fromAxisAngle(cornerPoint, angle / granularity, quaterion$1),
        rotMatrix$1
      );
    }

    var index = 0;
    startPoint = Cartesian3.clone(startPoint, scratch1$1);
    for (var i = 0; i < granularity; i++) {
      startPoint = Matrix3.multiplyByVector(m, startPoint, startPoint);
      array[index++] = startPoint.x;
      array[index++] = startPoint.y;
      array[index++] = startPoint.z;
    }

    return array;
  }

  function addEndCaps(calculatedPositions) {
    var cornerPoint = cartesian1;
    var startPoint = cartesian2;
    var endPoint = cartesian3;

    var leftEdge = calculatedPositions[1];
    startPoint = Cartesian3.fromArray(
      calculatedPositions[1],
      leftEdge.length - 3,
      startPoint
    );
    endPoint = Cartesian3.fromArray(calculatedPositions[0], 0, endPoint);
    cornerPoint = Cartesian3.midpoint(startPoint, endPoint, cornerPoint);
    var firstEndCap = computeRoundCorner$1(
      cornerPoint,
      startPoint,
      endPoint,
      CornerType$1.ROUNDED,
      false
    );

    var length = calculatedPositions.length - 1;
    var rightEdge = calculatedPositions[length - 1];
    leftEdge = calculatedPositions[length];
    startPoint = Cartesian3.fromArray(
      rightEdge,
      rightEdge.length - 3,
      startPoint
    );
    endPoint = Cartesian3.fromArray(leftEdge, 0, endPoint);
    cornerPoint = Cartesian3.midpoint(startPoint, endPoint, cornerPoint);
    var lastEndCap = computeRoundCorner$1(
      cornerPoint,
      startPoint,
      endPoint,
      CornerType$1.ROUNDED,
      false
    );

    return [firstEndCap, lastEndCap];
  }

  function computeMiteredCorner(
    position,
    leftCornerDirection,
    lastPoint,
    leftIsOutside
  ) {
    var cornerPoint = scratch1$1;
    if (leftIsOutside) {
      cornerPoint = Cartesian3.add(position, leftCornerDirection, cornerPoint);
    } else {
      leftCornerDirection = Cartesian3.negate(
        leftCornerDirection,
        leftCornerDirection
      );
      cornerPoint = Cartesian3.add(position, leftCornerDirection, cornerPoint);
    }
    return [
      cornerPoint.x,
      cornerPoint.y,
      cornerPoint.z,
      lastPoint.x,
      lastPoint.y,
      lastPoint.z,
    ];
  }

  function addShiftedPositions(positions, left, scalar, calculatedPositions) {
    var rightPositions = new Array(positions.length);
    var leftPositions = new Array(positions.length);
    var scaledLeft = Cartesian3.multiplyByScalar(left, scalar, scratch1$1);
    var scaledRight = Cartesian3.negate(scaledLeft, scratch2$1);
    var rightIndex = 0;
    var leftIndex = positions.length - 1;

    for (var i = 0; i < positions.length; i += 3) {
      var pos = Cartesian3.fromArray(positions, i, scratch3);
      var rightPos = Cartesian3.add(pos, scaledRight, scratch4);
      rightPositions[rightIndex++] = rightPos.x;
      rightPositions[rightIndex++] = rightPos.y;
      rightPositions[rightIndex++] = rightPos.z;

      var leftPos = Cartesian3.add(pos, scaledLeft, scratch4);
      leftPositions[leftIndex--] = leftPos.z;
      leftPositions[leftIndex--] = leftPos.y;
      leftPositions[leftIndex--] = leftPos.x;
    }
    calculatedPositions.push(rightPositions, leftPositions);

    return calculatedPositions;
  }

  /**
   * @private
   */
  CorridorGeometryLibrary.addAttribute = function (
    attribute,
    value,
    front,
    back
  ) {
    var x = value.x;
    var y = value.y;
    var z = value.z;
    if (defined(front)) {
      attribute[front] = x;
      attribute[front + 1] = y;
      attribute[front + 2] = z;
    }
    if (defined(back)) {
      attribute[back] = z;
      attribute[back - 1] = y;
      attribute[back - 2] = x;
    }
  };

  var scratchForwardProjection$1 = new Cartesian3();
  var scratchBackwardProjection$1 = new Cartesian3();

  /**
   * @private
   */
  CorridorGeometryLibrary.computePositions = function (params) {
    var granularity = params.granularity;
    var positions = params.positions;
    var ellipsoid = params.ellipsoid;
    var width = params.width / 2;
    var cornerType = params.cornerType;
    var saveAttributes = params.saveAttributes;
    var normal = cartesian1;
    var forward = cartesian2;
    var backward = cartesian3;
    var left = cartesian4;
    var cornerDirection = cartesian5;
    var startPoint = cartesian6;
    var previousPos = cartesian7;
    var rightPos = cartesian8;
    var leftPos = cartesian9;
    var center = cartesian10;
    var calculatedPositions = [];
    var calculatedLefts = saveAttributes ? [] : undefined;
    var calculatedNormals = saveAttributes ? [] : undefined;
    var position = positions[0]; //add first point
    var nextPosition = positions[1];

    forward = Cartesian3.normalize(
      Cartesian3.subtract(nextPosition, position, forward),
      forward
    );
    normal = ellipsoid.geodeticSurfaceNormal(position, normal);
    left = Cartesian3.normalize(Cartesian3.cross(normal, forward, left), left);
    if (saveAttributes) {
      calculatedLefts.push(left.x, left.y, left.z);
      calculatedNormals.push(normal.x, normal.y, normal.z);
    }
    previousPos = Cartesian3.clone(position, previousPos);
    position = nextPosition;
    backward = Cartesian3.negate(forward, backward);

    var subdividedPositions;
    var corners = [];
    var i;
    var length = positions.length;
    for (i = 1; i < length - 1; i++) {
      // add middle points and corners
      normal = ellipsoid.geodeticSurfaceNormal(position, normal);
      nextPosition = positions[i + 1];
      forward = Cartesian3.normalize(
        Cartesian3.subtract(nextPosition, position, forward),
        forward
      );
      cornerDirection = Cartesian3.normalize(
        Cartesian3.add(forward, backward, cornerDirection),
        cornerDirection
      );

      var forwardProjection = Cartesian3.multiplyByScalar(
        normal,
        Cartesian3.dot(forward, normal),
        scratchForwardProjection$1
      );
      Cartesian3.subtract(forward, forwardProjection, forwardProjection);
      Cartesian3.normalize(forwardProjection, forwardProjection);

      var backwardProjection = Cartesian3.multiplyByScalar(
        normal,
        Cartesian3.dot(backward, normal),
        scratchBackwardProjection$1
      );
      Cartesian3.subtract(backward, backwardProjection, backwardProjection);
      Cartesian3.normalize(backwardProjection, backwardProjection);

      var doCorner = !CesiumMath.equalsEpsilon(
        Math.abs(Cartesian3.dot(forwardProjection, backwardProjection)),
        1.0,
        CesiumMath.EPSILON7
      );

      if (doCorner) {
        cornerDirection = Cartesian3.cross(
          cornerDirection,
          normal,
          cornerDirection
        );
        cornerDirection = Cartesian3.cross(
          normal,
          cornerDirection,
          cornerDirection
        );
        cornerDirection = Cartesian3.normalize(cornerDirection, cornerDirection);
        var scalar =
          width /
          Math.max(
            0.25,
            Cartesian3.magnitude(
              Cartesian3.cross(cornerDirection, backward, scratch1$1)
            )
          );
        var leftIsOutside = PolylineVolumeGeometryLibrary.angleIsGreaterThanPi(
          forward,
          backward,
          position,
          ellipsoid
        );
        cornerDirection = Cartesian3.multiplyByScalar(
          cornerDirection,
          scalar,
          cornerDirection
        );
        if (leftIsOutside) {
          rightPos = Cartesian3.add(position, cornerDirection, rightPos);
          center = Cartesian3.add(
            rightPos,
            Cartesian3.multiplyByScalar(left, width, center),
            center
          );
          leftPos = Cartesian3.add(
            rightPos,
            Cartesian3.multiplyByScalar(left, width * 2, leftPos),
            leftPos
          );
          scaleArray2[0] = Cartesian3.clone(previousPos, scaleArray2[0]);
          scaleArray2[1] = Cartesian3.clone(center, scaleArray2[1]);
          subdividedPositions = PolylinePipeline.generateArc({
            positions: scaleArray2,
            granularity: granularity,
            ellipsoid: ellipsoid,
          });
          calculatedPositions = addShiftedPositions(
            subdividedPositions,
            left,
            width,
            calculatedPositions
          );
          if (saveAttributes) {
            calculatedLefts.push(left.x, left.y, left.z);
            calculatedNormals.push(normal.x, normal.y, normal.z);
          }
          startPoint = Cartesian3.clone(leftPos, startPoint);
          left = Cartesian3.normalize(
            Cartesian3.cross(normal, forward, left),
            left
          );
          leftPos = Cartesian3.add(
            rightPos,
            Cartesian3.multiplyByScalar(left, width * 2, leftPos),
            leftPos
          );
          previousPos = Cartesian3.add(
            rightPos,
            Cartesian3.multiplyByScalar(left, width, previousPos),
            previousPos
          );
          if (
            cornerType === CornerType$1.ROUNDED ||
            cornerType === CornerType$1.BEVELED
          ) {
            corners.push({
              leftPositions: computeRoundCorner$1(
                rightPos,
                startPoint,
                leftPos,
                cornerType,
                leftIsOutside
              ),
            });
          } else {
            corners.push({
              leftPositions: computeMiteredCorner(
                position,
                Cartesian3.negate(cornerDirection, cornerDirection),
                leftPos,
                leftIsOutside
              ),
            });
          }
        } else {
          leftPos = Cartesian3.add(position, cornerDirection, leftPos);
          center = Cartesian3.add(
            leftPos,
            Cartesian3.negate(
              Cartesian3.multiplyByScalar(left, width, center),
              center
            ),
            center
          );
          rightPos = Cartesian3.add(
            leftPos,
            Cartesian3.negate(
              Cartesian3.multiplyByScalar(left, width * 2, rightPos),
              rightPos
            ),
            rightPos
          );
          scaleArray2[0] = Cartesian3.clone(previousPos, scaleArray2[0]);
          scaleArray2[1] = Cartesian3.clone(center, scaleArray2[1]);
          subdividedPositions = PolylinePipeline.generateArc({
            positions: scaleArray2,
            granularity: granularity,
            ellipsoid: ellipsoid,
          });
          calculatedPositions = addShiftedPositions(
            subdividedPositions,
            left,
            width,
            calculatedPositions
          );
          if (saveAttributes) {
            calculatedLefts.push(left.x, left.y, left.z);
            calculatedNormals.push(normal.x, normal.y, normal.z);
          }
          startPoint = Cartesian3.clone(rightPos, startPoint);
          left = Cartesian3.normalize(
            Cartesian3.cross(normal, forward, left),
            left
          );
          rightPos = Cartesian3.add(
            leftPos,
            Cartesian3.negate(
              Cartesian3.multiplyByScalar(left, width * 2, rightPos),
              rightPos
            ),
            rightPos
          );
          previousPos = Cartesian3.add(
            leftPos,
            Cartesian3.negate(
              Cartesian3.multiplyByScalar(left, width, previousPos),
              previousPos
            ),
            previousPos
          );
          if (
            cornerType === CornerType$1.ROUNDED ||
            cornerType === CornerType$1.BEVELED
          ) {
            corners.push({
              rightPositions: computeRoundCorner$1(
                leftPos,
                startPoint,
                rightPos,
                cornerType,
                leftIsOutside
              ),
            });
          } else {
            corners.push({
              rightPositions: computeMiteredCorner(
                position,
                cornerDirection,
                rightPos,
                leftIsOutside
              ),
            });
          }
        }
        backward = Cartesian3.negate(forward, backward);
      }
      position = nextPosition;
    }

    normal = ellipsoid.geodeticSurfaceNormal(position, normal);
    scaleArray2[0] = Cartesian3.clone(previousPos, scaleArray2[0]);
    scaleArray2[1] = Cartesian3.clone(position, scaleArray2[1]);
    subdividedPositions = PolylinePipeline.generateArc({
      positions: scaleArray2,
      granularity: granularity,
      ellipsoid: ellipsoid,
    });
    calculatedPositions = addShiftedPositions(
      subdividedPositions,
      left,
      width,
      calculatedPositions
    );
    if (saveAttributes) {
      calculatedLefts.push(left.x, left.y, left.z);
      calculatedNormals.push(normal.x, normal.y, normal.z);
    }

    var endPositions;
    if (cornerType === CornerType$1.ROUNDED) {
      endPositions = addEndCaps(calculatedPositions);
    }

    return {
      positions: calculatedPositions,
      corners: corners,
      lefts: calculatedLefts,
      normals: calculatedNormals,
      endPositions: endPositions,
    };
  };

  var cartesian1$1 = new Cartesian3();
  var cartesian2$1 = new Cartesian3();
  var cartesian3$1 = new Cartesian3();
  var cartesian4$1 = new Cartesian3();
  var cartesian5$1 = new Cartesian3();
  var cartesian6$1 = new Cartesian3();

  var scratch1$2 = new Cartesian3();
  var scratch2$2 = new Cartesian3();

  function scaleToSurface$1(positions, ellipsoid) {
    for (var i = 0; i < positions.length; i++) {
      positions[i] = ellipsoid.scaleToGeodeticSurface(positions[i], positions[i]);
    }
    return positions;
  }

  function addNormals(attr, normal, left, front, back, vertexFormat) {
    var normals = attr.normals;
    var tangents = attr.tangents;
    var bitangents = attr.bitangents;
    var forward = Cartesian3.normalize(
      Cartesian3.cross(left, normal, scratch1$2),
      scratch1$2
    );
    if (vertexFormat.normal) {
      CorridorGeometryLibrary.addAttribute(normals, normal, front, back);
    }
    if (vertexFormat.tangent) {
      CorridorGeometryLibrary.addAttribute(tangents, forward, front, back);
    }
    if (vertexFormat.bitangent) {
      CorridorGeometryLibrary.addAttribute(bitangents, left, front, back);
    }
  }

  function combine$1(computedPositions, vertexFormat, ellipsoid) {
    var positions = computedPositions.positions;
    var corners = computedPositions.corners;
    var endPositions = computedPositions.endPositions;
    var computedLefts = computedPositions.lefts;
    var computedNormals = computedPositions.normals;
    var attributes = new GeometryAttributes();
    var corner;
    var leftCount = 0;
    var rightCount = 0;
    var i;
    var indicesLength = 0;
    var length;
    for (i = 0; i < positions.length; i += 2) {
      length = positions[i].length - 3;
      leftCount += length; //subtracting 3 to account for duplicate points at corners
      indicesLength += length * 2;
      rightCount += positions[i + 1].length - 3;
    }
    leftCount += 3; //add back count for end positions
    rightCount += 3;
    for (i = 0; i < corners.length; i++) {
      corner = corners[i];
      var leftSide = corners[i].leftPositions;
      if (defined(leftSide)) {
        length = leftSide.length;
        leftCount += length;
        indicesLength += length;
      } else {
        length = corners[i].rightPositions.length;
        rightCount += length;
        indicesLength += length;
      }
    }

    var addEndPositions = defined(endPositions);
    var endPositionLength;
    if (addEndPositions) {
      endPositionLength = endPositions[0].length - 3;
      leftCount += endPositionLength;
      rightCount += endPositionLength;
      endPositionLength /= 3;
      indicesLength += endPositionLength * 6;
    }
    var size = leftCount + rightCount;
    var finalPositions = new Float64Array(size);
    var normals = vertexFormat.normal ? new Float32Array(size) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(size) : undefined;
    var bitangents = vertexFormat.bitangent ? new Float32Array(size) : undefined;
    var attr = {
      normals: normals,
      tangents: tangents,
      bitangents: bitangents,
    };
    var front = 0;
    var back = size - 1;
    var UL, LL, UR, LR;
    var normal = cartesian1$1;
    var left = cartesian2$1;
    var rightPos, leftPos;
    var halfLength = endPositionLength / 2;

    var indices = IndexDatatype$1.createTypedArray(size / 3, indicesLength);
    var index = 0;
    if (addEndPositions) {
      // add rounded end
      leftPos = cartesian3$1;
      rightPos = cartesian4$1;
      var firstEndPositions = endPositions[0];
      normal = Cartesian3.fromArray(computedNormals, 0, normal);
      left = Cartesian3.fromArray(computedLefts, 0, left);
      for (i = 0; i < halfLength; i++) {
        leftPos = Cartesian3.fromArray(
          firstEndPositions,
          (halfLength - 1 - i) * 3,
          leftPos
        );
        rightPos = Cartesian3.fromArray(
          firstEndPositions,
          (halfLength + i) * 3,
          rightPos
        );
        CorridorGeometryLibrary.addAttribute(finalPositions, rightPos, front);
        CorridorGeometryLibrary.addAttribute(
          finalPositions,
          leftPos,
          undefined,
          back
        );
        addNormals(attr, normal, left, front, back, vertexFormat);

        LL = front / 3;
        LR = LL + 1;
        UL = (back - 2) / 3;
        UR = UL - 1;
        indices[index++] = UL;
        indices[index++] = LL;
        indices[index++] = UR;
        indices[index++] = UR;
        indices[index++] = LL;
        indices[index++] = LR;

        front += 3;
        back -= 3;
      }
    }

    var posIndex = 0;
    var compIndex = 0;
    var rightEdge = positions[posIndex++]; //add first two edges
    var leftEdge = positions[posIndex++];
    finalPositions.set(rightEdge, front);
    finalPositions.set(leftEdge, back - leftEdge.length + 1);

    left = Cartesian3.fromArray(computedLefts, compIndex, left);
    var rightNormal;
    var leftNormal;
    length = leftEdge.length - 3;
    for (i = 0; i < length; i += 3) {
      rightNormal = ellipsoid.geodeticSurfaceNormal(
        Cartesian3.fromArray(rightEdge, i, scratch1$2),
        scratch1$2
      );
      leftNormal = ellipsoid.geodeticSurfaceNormal(
        Cartesian3.fromArray(leftEdge, length - i, scratch2$2),
        scratch2$2
      );
      normal = Cartesian3.normalize(
        Cartesian3.add(rightNormal, leftNormal, normal),
        normal
      );
      addNormals(attr, normal, left, front, back, vertexFormat);

      LL = front / 3;
      LR = LL + 1;
      UL = (back - 2) / 3;
      UR = UL - 1;
      indices[index++] = UL;
      indices[index++] = LL;
      indices[index++] = UR;
      indices[index++] = UR;
      indices[index++] = LL;
      indices[index++] = LR;

      front += 3;
      back -= 3;
    }

    rightNormal = ellipsoid.geodeticSurfaceNormal(
      Cartesian3.fromArray(rightEdge, length, scratch1$2),
      scratch1$2
    );
    leftNormal = ellipsoid.geodeticSurfaceNormal(
      Cartesian3.fromArray(leftEdge, length, scratch2$2),
      scratch2$2
    );
    normal = Cartesian3.normalize(
      Cartesian3.add(rightNormal, leftNormal, normal),
      normal
    );
    compIndex += 3;
    for (i = 0; i < corners.length; i++) {
      var j;
      corner = corners[i];
      var l = corner.leftPositions;
      var r = corner.rightPositions;
      var pivot;
      var start;
      var outsidePoint = cartesian6$1;
      var previousPoint = cartesian3$1;
      var nextPoint = cartesian4$1;
      normal = Cartesian3.fromArray(computedNormals, compIndex, normal);
      if (defined(l)) {
        addNormals(attr, normal, left, undefined, back, vertexFormat);
        back -= 3;
        pivot = LR;
        start = UR;
        for (j = 0; j < l.length / 3; j++) {
          outsidePoint = Cartesian3.fromArray(l, j * 3, outsidePoint);
          indices[index++] = pivot;
          indices[index++] = start - j - 1;
          indices[index++] = start - j;
          CorridorGeometryLibrary.addAttribute(
            finalPositions,
            outsidePoint,
            undefined,
            back
          );
          previousPoint = Cartesian3.fromArray(
            finalPositions,
            (start - j - 1) * 3,
            previousPoint
          );
          nextPoint = Cartesian3.fromArray(finalPositions, pivot * 3, nextPoint);
          left = Cartesian3.normalize(
            Cartesian3.subtract(previousPoint, nextPoint, left),
            left
          );
          addNormals(attr, normal, left, undefined, back, vertexFormat);
          back -= 3;
        }
        outsidePoint = Cartesian3.fromArray(
          finalPositions,
          pivot * 3,
          outsidePoint
        );
        previousPoint = Cartesian3.subtract(
          Cartesian3.fromArray(finalPositions, start * 3, previousPoint),
          outsidePoint,
          previousPoint
        );
        nextPoint = Cartesian3.subtract(
          Cartesian3.fromArray(finalPositions, (start - j) * 3, nextPoint),
          outsidePoint,
          nextPoint
        );
        left = Cartesian3.normalize(
          Cartesian3.add(previousPoint, nextPoint, left),
          left
        );
        addNormals(attr, normal, left, front, undefined, vertexFormat);
        front += 3;
      } else {
        addNormals(attr, normal, left, front, undefined, vertexFormat);
        front += 3;
        pivot = UR;
        start = LR;
        for (j = 0; j < r.length / 3; j++) {
          outsidePoint = Cartesian3.fromArray(r, j * 3, outsidePoint);
          indices[index++] = pivot;
          indices[index++] = start + j;
          indices[index++] = start + j + 1;
          CorridorGeometryLibrary.addAttribute(
            finalPositions,
            outsidePoint,
            front
          );
          previousPoint = Cartesian3.fromArray(
            finalPositions,
            pivot * 3,
            previousPoint
          );
          nextPoint = Cartesian3.fromArray(
            finalPositions,
            (start + j) * 3,
            nextPoint
          );
          left = Cartesian3.normalize(
            Cartesian3.subtract(previousPoint, nextPoint, left),
            left
          );
          addNormals(attr, normal, left, front, undefined, vertexFormat);
          front += 3;
        }
        outsidePoint = Cartesian3.fromArray(
          finalPositions,
          pivot * 3,
          outsidePoint
        );
        previousPoint = Cartesian3.subtract(
          Cartesian3.fromArray(finalPositions, (start + j) * 3, previousPoint),
          outsidePoint,
          previousPoint
        );
        nextPoint = Cartesian3.subtract(
          Cartesian3.fromArray(finalPositions, start * 3, nextPoint),
          outsidePoint,
          nextPoint
        );
        left = Cartesian3.normalize(
          Cartesian3.negate(Cartesian3.add(nextPoint, previousPoint, left), left),
          left
        );
        addNormals(attr, normal, left, undefined, back, vertexFormat);
        back -= 3;
      }
      rightEdge = positions[posIndex++];
      leftEdge = positions[posIndex++];
      rightEdge.splice(0, 3); //remove duplicate points added by corner
      leftEdge.splice(leftEdge.length - 3, 3);
      finalPositions.set(rightEdge, front);
      finalPositions.set(leftEdge, back - leftEdge.length + 1);
      length = leftEdge.length - 3;

      compIndex += 3;
      left = Cartesian3.fromArray(computedLefts, compIndex, left);
      for (j = 0; j < leftEdge.length; j += 3) {
        rightNormal = ellipsoid.geodeticSurfaceNormal(
          Cartesian3.fromArray(rightEdge, j, scratch1$2),
          scratch1$2
        );
        leftNormal = ellipsoid.geodeticSurfaceNormal(
          Cartesian3.fromArray(leftEdge, length - j, scratch2$2),
          scratch2$2
        );
        normal = Cartesian3.normalize(
          Cartesian3.add(rightNormal, leftNormal, normal),
          normal
        );
        addNormals(attr, normal, left, front, back, vertexFormat);

        LR = front / 3;
        LL = LR - 1;
        UR = (back - 2) / 3;
        UL = UR + 1;
        indices[index++] = UL;
        indices[index++] = LL;
        indices[index++] = UR;
        indices[index++] = UR;
        indices[index++] = LL;
        indices[index++] = LR;

        front += 3;
        back -= 3;
      }
      front -= 3;
      back += 3;
    }
    normal = Cartesian3.fromArray(
      computedNormals,
      computedNormals.length - 3,
      normal
    );
    addNormals(attr, normal, left, front, back, vertexFormat);

    if (addEndPositions) {
      // add rounded end
      front += 3;
      back -= 3;
      leftPos = cartesian3$1;
      rightPos = cartesian4$1;
      var lastEndPositions = endPositions[1];
      for (i = 0; i < halfLength; i++) {
        leftPos = Cartesian3.fromArray(
          lastEndPositions,
          (endPositionLength - i - 1) * 3,
          leftPos
        );
        rightPos = Cartesian3.fromArray(lastEndPositions, i * 3, rightPos);
        CorridorGeometryLibrary.addAttribute(
          finalPositions,
          leftPos,
          undefined,
          back
        );
        CorridorGeometryLibrary.addAttribute(finalPositions, rightPos, front);
        addNormals(attr, normal, left, front, back, vertexFormat);

        LR = front / 3;
        LL = LR - 1;
        UR = (back - 2) / 3;
        UL = UR + 1;
        indices[index++] = UL;
        indices[index++] = LL;
        indices[index++] = UR;
        indices[index++] = UR;
        indices[index++] = LL;
        indices[index++] = LR;

        front += 3;
        back -= 3;
      }
    }

    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: finalPositions,
    });

    if (vertexFormat.st) {
      var st = new Float32Array((size / 3) * 2);
      var rightSt;
      var leftSt;
      var stIndex = 0;
      if (addEndPositions) {
        leftCount /= 3;
        rightCount /= 3;
        var theta = Math.PI / (endPositionLength + 1);
        leftSt = 1 / (leftCount - endPositionLength + 1);
        rightSt = 1 / (rightCount - endPositionLength + 1);
        var a;
        var halfEndPos = endPositionLength / 2;
        for (i = halfEndPos + 1; i < endPositionLength + 1; i++) {
          // lower left rounded end
          a = CesiumMath.PI_OVER_TWO + theta * i;
          st[stIndex++] = rightSt * (1 + Math.cos(a));
          st[stIndex++] = 0.5 * (1 + Math.sin(a));
        }
        for (i = 1; i < rightCount - endPositionLength + 1; i++) {
          // bottom edge
          st[stIndex++] = i * rightSt;
          st[stIndex++] = 0;
        }
        for (i = endPositionLength; i > halfEndPos; i--) {
          // lower right rounded end
          a = CesiumMath.PI_OVER_TWO - i * theta;
          st[stIndex++] = 1 - rightSt * (1 + Math.cos(a));
          st[stIndex++] = 0.5 * (1 + Math.sin(a));
        }
        for (i = halfEndPos; i > 0; i--) {
          // upper right rounded end
          a = CesiumMath.PI_OVER_TWO - theta * i;
          st[stIndex++] = 1 - leftSt * (1 + Math.cos(a));
          st[stIndex++] = 0.5 * (1 + Math.sin(a));
        }
        for (i = leftCount - endPositionLength; i > 0; i--) {
          // top edge
          st[stIndex++] = i * leftSt;
          st[stIndex++] = 1;
        }
        for (i = 1; i < halfEndPos + 1; i++) {
          // upper left rounded end
          a = CesiumMath.PI_OVER_TWO + theta * i;
          st[stIndex++] = leftSt * (1 + Math.cos(a));
          st[stIndex++] = 0.5 * (1 + Math.sin(a));
        }
      } else {
        leftCount /= 3;
        rightCount /= 3;
        leftSt = 1 / (leftCount - 1);
        rightSt = 1 / (rightCount - 1);
        for (i = 0; i < rightCount; i++) {
          // bottom edge
          st[stIndex++] = i * rightSt;
          st[stIndex++] = 0;
        }
        for (i = leftCount; i > 0; i--) {
          // top edge
          st[stIndex++] = (i - 1) * leftSt;
          st[stIndex++] = 1;
        }
      }

      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: st,
      });
    }

    if (vertexFormat.normal) {
      attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: attr.normals,
      });
    }

    if (vertexFormat.tangent) {
      attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: attr.tangents,
      });
    }

    if (vertexFormat.bitangent) {
      attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: attr.bitangents,
      });
    }

    return {
      attributes: attributes,
      indices: indices,
    };
  }

  function extrudedAttributes(attributes, vertexFormat) {
    if (
      !vertexFormat.normal &&
      !vertexFormat.tangent &&
      !vertexFormat.bitangent &&
      !vertexFormat.st
    ) {
      return attributes;
    }
    var positions = attributes.position.values;
    var topNormals;
    var topBitangents;
    if (vertexFormat.normal || vertexFormat.bitangent) {
      topNormals = attributes.normal.values;
      topBitangents = attributes.bitangent.values;
    }
    var size = attributes.position.values.length / 18;
    var threeSize = size * 3;
    var twoSize = size * 2;
    var sixSize = threeSize * 2;
    var i;
    if (vertexFormat.normal || vertexFormat.bitangent || vertexFormat.tangent) {
      var normals = vertexFormat.normal
        ? new Float32Array(threeSize * 6)
        : undefined;
      var tangents = vertexFormat.tangent
        ? new Float32Array(threeSize * 6)
        : undefined;
      var bitangents = vertexFormat.bitangent
        ? new Float32Array(threeSize * 6)
        : undefined;
      var topPosition = cartesian1$1;
      var bottomPosition = cartesian2$1;
      var previousPosition = cartesian3$1;
      var normal = cartesian4$1;
      var tangent = cartesian5$1;
      var bitangent = cartesian6$1;
      var attrIndex = sixSize;
      for (i = 0; i < threeSize; i += 3) {
        var attrIndexOffset = attrIndex + sixSize;
        topPosition = Cartesian3.fromArray(positions, i, topPosition);
        bottomPosition = Cartesian3.fromArray(
          positions,
          i + threeSize,
          bottomPosition
        );
        previousPosition = Cartesian3.fromArray(
          positions,
          (i + 3) % threeSize,
          previousPosition
        );
        bottomPosition = Cartesian3.subtract(
          bottomPosition,
          topPosition,
          bottomPosition
        );
        previousPosition = Cartesian3.subtract(
          previousPosition,
          topPosition,
          previousPosition
        );
        normal = Cartesian3.normalize(
          Cartesian3.cross(bottomPosition, previousPosition, normal),
          normal
        );
        if (vertexFormat.normal) {
          CorridorGeometryLibrary.addAttribute(normals, normal, attrIndexOffset);
          CorridorGeometryLibrary.addAttribute(
            normals,
            normal,
            attrIndexOffset + 3
          );
          CorridorGeometryLibrary.addAttribute(normals, normal, attrIndex);
          CorridorGeometryLibrary.addAttribute(normals, normal, attrIndex + 3);
        }
        if (vertexFormat.tangent || vertexFormat.bitangent) {
          bitangent = Cartesian3.fromArray(topNormals, i, bitangent);
          if (vertexFormat.bitangent) {
            CorridorGeometryLibrary.addAttribute(
              bitangents,
              bitangent,
              attrIndexOffset
            );
            CorridorGeometryLibrary.addAttribute(
              bitangents,
              bitangent,
              attrIndexOffset + 3
            );
            CorridorGeometryLibrary.addAttribute(
              bitangents,
              bitangent,
              attrIndex
            );
            CorridorGeometryLibrary.addAttribute(
              bitangents,
              bitangent,
              attrIndex + 3
            );
          }

          if (vertexFormat.tangent) {
            tangent = Cartesian3.normalize(
              Cartesian3.cross(bitangent, normal, tangent),
              tangent
            );
            CorridorGeometryLibrary.addAttribute(
              tangents,
              tangent,
              attrIndexOffset
            );
            CorridorGeometryLibrary.addAttribute(
              tangents,
              tangent,
              attrIndexOffset + 3
            );
            CorridorGeometryLibrary.addAttribute(tangents, tangent, attrIndex);
            CorridorGeometryLibrary.addAttribute(
              tangents,
              tangent,
              attrIndex + 3
            );
          }
        }
        attrIndex += 6;
      }

      if (vertexFormat.normal) {
        normals.set(topNormals); //top
        for (i = 0; i < threeSize; i += 3) {
          //bottom normals
          normals[i + threeSize] = -topNormals[i];
          normals[i + threeSize + 1] = -topNormals[i + 1];
          normals[i + threeSize + 2] = -topNormals[i + 2];
        }
        attributes.normal.values = normals;
      } else {
        attributes.normal = undefined;
      }

      if (vertexFormat.bitangent) {
        bitangents.set(topBitangents); //top
        bitangents.set(topBitangents, threeSize); //bottom
        attributes.bitangent.values = bitangents;
      } else {
        attributes.bitangent = undefined;
      }

      if (vertexFormat.tangent) {
        var topTangents = attributes.tangent.values;
        tangents.set(topTangents); //top
        tangents.set(topTangents, threeSize); //bottom
        attributes.tangent.values = tangents;
      }
    }
    if (vertexFormat.st) {
      var topSt = attributes.st.values;
      var st = new Float32Array(twoSize * 6);
      st.set(topSt); //top
      st.set(topSt, twoSize); //bottom
      var index = twoSize * 2;

      for (var j = 0; j < 2; j++) {
        st[index++] = topSt[0];
        st[index++] = topSt[1];
        for (i = 2; i < twoSize; i += 2) {
          var s = topSt[i];
          var t = topSt[i + 1];
          st[index++] = s;
          st[index++] = t;
          st[index++] = s;
          st[index++] = t;
        }
        st[index++] = topSt[0];
        st[index++] = topSt[1];
      }
      attributes.st.values = st;
    }

    return attributes;
  }

  function addWallPositions(positions, index, wallPositions) {
    wallPositions[index++] = positions[0];
    wallPositions[index++] = positions[1];
    wallPositions[index++] = positions[2];
    for (var i = 3; i < positions.length; i += 3) {
      var x = positions[i];
      var y = positions[i + 1];
      var z = positions[i + 2];
      wallPositions[index++] = x;
      wallPositions[index++] = y;
      wallPositions[index++] = z;
      wallPositions[index++] = x;
      wallPositions[index++] = y;
      wallPositions[index++] = z;
    }
    wallPositions[index++] = positions[0];
    wallPositions[index++] = positions[1];
    wallPositions[index++] = positions[2];

    return wallPositions;
  }

  function computePositionsExtruded(params, vertexFormat) {
    var topVertexFormat = new VertexFormat({
      position: vertexFormat.position,
      normal:
        vertexFormat.normal || vertexFormat.bitangent || params.shadowVolume,
      tangent: vertexFormat.tangent,
      bitangent: vertexFormat.normal || vertexFormat.bitangent,
      st: vertexFormat.st,
    });
    var ellipsoid = params.ellipsoid;
    var computedPositions = CorridorGeometryLibrary.computePositions(params);
    var attr = combine$1(computedPositions, topVertexFormat, ellipsoid);
    var height = params.height;
    var extrudedHeight = params.extrudedHeight;
    var attributes = attr.attributes;
    var indices = attr.indices;
    var positions = attributes.position.values;
    var length = positions.length;
    var newPositions = new Float64Array(length * 6);
    var extrudedPositions = new Float64Array(length);
    extrudedPositions.set(positions);
    var wallPositions = new Float64Array(length * 4);

    positions = PolygonPipeline.scaleToGeodeticHeight(
      positions,
      height,
      ellipsoid
    );
    wallPositions = addWallPositions(positions, 0, wallPositions);
    extrudedPositions = PolygonPipeline.scaleToGeodeticHeight(
      extrudedPositions,
      extrudedHeight,
      ellipsoid
    );
    wallPositions = addWallPositions(
      extrudedPositions,
      length * 2,
      wallPositions
    );
    newPositions.set(positions);
    newPositions.set(extrudedPositions, length);
    newPositions.set(wallPositions, length * 2);
    attributes.position.values = newPositions;

    attributes = extrudedAttributes(attributes, vertexFormat);
    var i;
    var size = length / 3;
    if (params.shadowVolume) {
      var topNormals = attributes.normal.values;
      length = topNormals.length;

      var extrudeNormals = new Float32Array(length * 6);
      for (i = 0; i < length; i++) {
        topNormals[i] = -topNormals[i];
      }
      //only get normals for bottom layer that's going to be pushed down
      extrudeNormals.set(topNormals, length); //bottom face
      extrudeNormals = addWallPositions(topNormals, length * 4, extrudeNormals); //bottom wall
      attributes.extrudeDirection = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: extrudeNormals,
      });
      if (!vertexFormat.normal) {
        attributes.normal = undefined;
      }
    }
    if (defined(params.offsetAttribute)) {
      var applyOffset = new Uint8Array(size * 6);
      if (params.offsetAttribute === GeometryOffsetAttribute$1.TOP) {
        applyOffset = arrayFill(applyOffset, 1, 0, size); // top face
        applyOffset = arrayFill(applyOffset, 1, size * 2, size * 4); // top wall
      } else {
        var applyOffsetValue =
          params.offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        applyOffset = arrayFill(applyOffset, applyOffsetValue);
      }
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    var iLength = indices.length;
    var twoSize = size + size;
    var newIndices = IndexDatatype$1.createTypedArray(
      newPositions.length / 3,
      iLength * 2 + twoSize * 3
    );
    newIndices.set(indices);
    var index = iLength;
    for (i = 0; i < iLength; i += 3) {
      // bottom indices
      var v0 = indices[i];
      var v1 = indices[i + 1];
      var v2 = indices[i + 2];
      newIndices[index++] = v2 + size;
      newIndices[index++] = v1 + size;
      newIndices[index++] = v0 + size;
    }

    var UL, LL, UR, LR;

    for (i = 0; i < twoSize; i += 2) {
      //wall indices
      UL = i + twoSize;
      LL = UL + twoSize;
      UR = UL + 1;
      LR = LL + 1;
      newIndices[index++] = UL;
      newIndices[index++] = LL;
      newIndices[index++] = UR;
      newIndices[index++] = UR;
      newIndices[index++] = LL;
      newIndices[index++] = LR;
    }

    return {
      attributes: attributes,
      indices: newIndices,
    };
  }

  var scratchCartesian1$6 = new Cartesian3();
  var scratchCartesian2$6 = new Cartesian3();
  var scratchCartographic$2 = new Cartographic();

  function computeOffsetPoints(
    position1,
    position2,
    ellipsoid,
    halfWidth,
    min,
    max
  ) {
    // Compute direction of offset the point
    var direction = Cartesian3.subtract(position2, position1, scratchCartesian1$6);
    Cartesian3.normalize(direction, direction);
    var normal = ellipsoid.geodeticSurfaceNormal(position1, scratchCartesian2$6);
    var offsetDirection = Cartesian3.cross(direction, normal, scratchCartesian1$6);
    Cartesian3.multiplyByScalar(offsetDirection, halfWidth, offsetDirection);

    var minLat = min.latitude;
    var minLon = min.longitude;
    var maxLat = max.latitude;
    var maxLon = max.longitude;

    // Compute 2 offset points
    Cartesian3.add(position1, offsetDirection, scratchCartesian2$6);
    ellipsoid.cartesianToCartographic(scratchCartesian2$6, scratchCartographic$2);

    var lat = scratchCartographic$2.latitude;
    var lon = scratchCartographic$2.longitude;
    minLat = Math.min(minLat, lat);
    minLon = Math.min(minLon, lon);
    maxLat = Math.max(maxLat, lat);
    maxLon = Math.max(maxLon, lon);

    Cartesian3.subtract(position1, offsetDirection, scratchCartesian2$6);
    ellipsoid.cartesianToCartographic(scratchCartesian2$6, scratchCartographic$2);

    lat = scratchCartographic$2.latitude;
    lon = scratchCartographic$2.longitude;
    minLat = Math.min(minLat, lat);
    minLon = Math.min(minLon, lon);
    maxLat = Math.max(maxLat, lat);
    maxLon = Math.max(maxLon, lon);

    min.latitude = minLat;
    min.longitude = minLon;
    max.latitude = maxLat;
    max.longitude = maxLon;
  }

  var scratchCartesianOffset = new Cartesian3();
  var scratchCartesianEnds = new Cartesian3();
  var scratchCartographicMin = new Cartographic();
  var scratchCartographicMax = new Cartographic();

  function computeRectangle$1(positions, ellipsoid, width, cornerType, result) {
    positions = scaleToSurface$1(positions, ellipsoid);
    var cleanPositions = arrayRemoveDuplicates(
      positions,
      Cartesian3.equalsEpsilon
    );
    var length = cleanPositions.length;
    if (length < 2 || width <= 0) {
      return new Rectangle();
    }
    var halfWidth = width * 0.5;

    scratchCartographicMin.latitude = Number.POSITIVE_INFINITY;
    scratchCartographicMin.longitude = Number.POSITIVE_INFINITY;
    scratchCartographicMax.latitude = Number.NEGATIVE_INFINITY;
    scratchCartographicMax.longitude = Number.NEGATIVE_INFINITY;

    var lat, lon;
    if (cornerType === CornerType$1.ROUNDED) {
      // Compute start cap
      var first = cleanPositions[0];
      Cartesian3.subtract(first, cleanPositions[1], scratchCartesianOffset);
      Cartesian3.normalize(scratchCartesianOffset, scratchCartesianOffset);
      Cartesian3.multiplyByScalar(
        scratchCartesianOffset,
        halfWidth,
        scratchCartesianOffset
      );
      Cartesian3.add(first, scratchCartesianOffset, scratchCartesianEnds);

      ellipsoid.cartesianToCartographic(
        scratchCartesianEnds,
        scratchCartographic$2
      );
      lat = scratchCartographic$2.latitude;
      lon = scratchCartographic$2.longitude;
      scratchCartographicMin.latitude = Math.min(
        scratchCartographicMin.latitude,
        lat
      );
      scratchCartographicMin.longitude = Math.min(
        scratchCartographicMin.longitude,
        lon
      );
      scratchCartographicMax.latitude = Math.max(
        scratchCartographicMax.latitude,
        lat
      );
      scratchCartographicMax.longitude = Math.max(
        scratchCartographicMax.longitude,
        lon
      );
    }

    // Compute the rest
    for (var i = 0; i < length - 1; ++i) {
      computeOffsetPoints(
        cleanPositions[i],
        cleanPositions[i + 1],
        ellipsoid,
        halfWidth,
        scratchCartographicMin,
        scratchCartographicMax
      );
    }

    // Compute ending point
    var last = cleanPositions[length - 1];
    Cartesian3.subtract(last, cleanPositions[length - 2], scratchCartesianOffset);
    Cartesian3.normalize(scratchCartesianOffset, scratchCartesianOffset);
    Cartesian3.multiplyByScalar(
      scratchCartesianOffset,
      halfWidth,
      scratchCartesianOffset
    );
    Cartesian3.add(last, scratchCartesianOffset, scratchCartesianEnds);
    computeOffsetPoints(
      last,
      scratchCartesianEnds,
      ellipsoid,
      halfWidth,
      scratchCartographicMin,
      scratchCartographicMax
    );

    if (cornerType === CornerType$1.ROUNDED) {
      // Compute end cap
      ellipsoid.cartesianToCartographic(
        scratchCartesianEnds,
        scratchCartographic$2
      );
      lat = scratchCartographic$2.latitude;
      lon = scratchCartographic$2.longitude;
      scratchCartographicMin.latitude = Math.min(
        scratchCartographicMin.latitude,
        lat
      );
      scratchCartographicMin.longitude = Math.min(
        scratchCartographicMin.longitude,
        lon
      );
      scratchCartographicMax.latitude = Math.max(
        scratchCartographicMax.latitude,
        lat
      );
      scratchCartographicMax.longitude = Math.max(
        scratchCartographicMax.longitude,
        lon
      );
    }

    var rectangle = defined(result) ? result : new Rectangle();
    rectangle.north = scratchCartographicMax.latitude;
    rectangle.south = scratchCartographicMin.latitude;
    rectangle.east = scratchCartographicMax.longitude;
    rectangle.west = scratchCartographicMin.longitude;

    return rectangle;
  }

  /**
   * A description of a corridor. Corridor geometry can be rendered with both {@link Primitive} and {@link GroundPrimitive}.
   *
   * @alias CorridorGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that define the center of the corridor.
   * @param {Number} options.width The distance between the edges of the corridor in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number} [options.height=0] The distance in meters between the ellipsoid surface and the positions.
   * @param {Number} [options.extrudedHeight] The distance in meters between the ellipsoid surface and the extruded face.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {CornerType} [options.cornerType=CornerType.ROUNDED] Determines the style of the corners.
   *
   * @see CorridorGeometry.createGeometry
   * @see Packable
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Corridor.html|Cesium Sandcastle Corridor Demo}
   *
   * @example
   * var corridor = new Cesium.CorridorGeometry({
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY,
   *   positions : Cesium.Cartesian3.fromDegreesArray([-72.0, 40.0, -70.0, 35.0]),
   *   width : 100000
   * });
   */
  function CorridorGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;
    var width = options.width;

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.positions", positions);
    Check.defined("options.width", width);
    //>>includeEnd('debug');

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    this._positions = positions;
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._vertexFormat = VertexFormat.clone(
      defaultValue(options.vertexFormat, VertexFormat.DEFAULT)
    );
    this._width = width;
    this._height = Math.max(height, extrudedHeight);
    this._extrudedHeight = Math.min(height, extrudedHeight);
    this._cornerType = defaultValue(options.cornerType, CornerType$1.ROUNDED);
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._shadowVolume = defaultValue(options.shadowVolume, false);
    this._workerName = "createCorridorGeometry";
    this._offsetAttribute = options.offsetAttribute;
    this._rectangle = undefined;

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      1 +
      positions.length * Cartesian3.packedLength +
      Ellipsoid.packedLength +
      VertexFormat.packedLength +
      7;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CorridorGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CorridorGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (var i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._width;
    array[startingIndex++] = value._height;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._cornerType;
    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._shadowVolume ? 1.0 : 0.0;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchEllipsoid$3 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchVertexFormat$3 = new VertexFormat();
  var scratchOptions$8 = {
    positions: undefined,
    ellipsoid: scratchEllipsoid$3,
    vertexFormat: scratchVertexFormat$3,
    width: undefined,
    height: undefined,
    extrudedHeight: undefined,
    cornerType: undefined,
    granularity: undefined,
    shadowVolume: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CorridorGeometry} [result] The object into which to store the result.
   * @returns {CorridorGeometry} The modified result parameter or a new CorridorGeometry instance if one was not provided.
   */
  CorridorGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (var i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$3);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$3
    );
    startingIndex += VertexFormat.packedLength;

    var width = array[startingIndex++];
    var height = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var cornerType = array[startingIndex++];
    var granularity = array[startingIndex++];
    var shadowVolume = array[startingIndex++] === 1.0;
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$8.positions = positions;
      scratchOptions$8.width = width;
      scratchOptions$8.height = height;
      scratchOptions$8.extrudedHeight = extrudedHeight;
      scratchOptions$8.cornerType = cornerType;
      scratchOptions$8.granularity = granularity;
      scratchOptions$8.shadowVolume = shadowVolume;
      scratchOptions$8.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;

      return new CorridorGeometry(scratchOptions$8);
    }

    result._positions = positions;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._width = width;
    result._height = height;
    result._extrudedHeight = extrudedHeight;
    result._cornerType = cornerType;
    result._granularity = granularity;
    result._shadowVolume = shadowVolume;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the bounding rectangle given the provided options
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that define the center of the corridor.
   * @param {Number} options.width The distance between the edges of the corridor in meters.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {CornerType} [options.cornerType=CornerType.ROUNDED] Determines the style of the corners.
   * @param {Rectangle} [result] An object in which to store the result.
   *
   * @returns {Rectangle} The result rectangle.
   */
  CorridorGeometry.computeRectangle = function (options, result) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;
    var width = options.width;

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.positions", positions);
    Check.defined("options.width", width);
    //>>includeEnd('debug');

    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var cornerType = defaultValue(options.cornerType, CornerType$1.ROUNDED);

    return computeRectangle$1(positions, ellipsoid, width, cornerType, result);
  };

  /**
   * Computes the geometric representation of a corridor, including its vertices, indices, and a bounding sphere.
   *
   * @param {CorridorGeometry} corridorGeometry A description of the corridor.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CorridorGeometry.createGeometry = function (corridorGeometry) {
    var positions = corridorGeometry._positions;
    var width = corridorGeometry._width;
    var ellipsoid = corridorGeometry._ellipsoid;

    positions = scaleToSurface$1(positions, ellipsoid);
    var cleanPositions = arrayRemoveDuplicates(
      positions,
      Cartesian3.equalsEpsilon
    );

    if (cleanPositions.length < 2 || width <= 0) {
      return;
    }

    var height = corridorGeometry._height;
    var extrudedHeight = corridorGeometry._extrudedHeight;
    var extrude = !CesiumMath.equalsEpsilon(
      height,
      extrudedHeight,
      0,
      CesiumMath.EPSILON2
    );

    var vertexFormat = corridorGeometry._vertexFormat;
    var params = {
      ellipsoid: ellipsoid,
      positions: cleanPositions,
      width: width,
      cornerType: corridorGeometry._cornerType,
      granularity: corridorGeometry._granularity,
      saveAttributes: true,
    };
    var attr;
    if (extrude) {
      params.height = height;
      params.extrudedHeight = extrudedHeight;
      params.shadowVolume = corridorGeometry._shadowVolume;
      params.offsetAttribute = corridorGeometry._offsetAttribute;
      attr = computePositionsExtruded(params, vertexFormat);
    } else {
      var computedPositions = CorridorGeometryLibrary.computePositions(params);
      attr = combine$1(computedPositions, vertexFormat, ellipsoid);
      attr.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
        attr.attributes.position.values,
        height,
        ellipsoid
      );

      if (defined(corridorGeometry._offsetAttribute)) {
        var applyOffsetValue =
          corridorGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
            ? 0
            : 1;
        var length = attr.attributes.position.values.length;
        var applyOffset = new Uint8Array(length / 3);
        arrayFill(applyOffset, applyOffsetValue);
        attr.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: applyOffset,
        });
      }
    }
    var attributes = attr.attributes;
    var boundingSphere = BoundingSphere.fromVertices(
      attributes.position.values,
      undefined,
      3
    );
    if (!vertexFormat.position) {
      attr.attributes.position.values = undefined;
    }

    return new Geometry({
      attributes: attributes,
      indices: attr.indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: boundingSphere,
      offsetAttribute: corridorGeometry._offsetAttribute,
    });
  };

  /**
   * @private
   */
  CorridorGeometry.createShadowVolume = function (
    corridorGeometry,
    minHeightFunc,
    maxHeightFunc
  ) {
    var granularity = corridorGeometry._granularity;
    var ellipsoid = corridorGeometry._ellipsoid;

    var minHeight = minHeightFunc(granularity, ellipsoid);
    var maxHeight = maxHeightFunc(granularity, ellipsoid);

    return new CorridorGeometry({
      positions: corridorGeometry._positions,
      width: corridorGeometry._width,
      cornerType: corridorGeometry._cornerType,
      ellipsoid: ellipsoid,
      granularity: granularity,
      extrudedHeight: minHeight,
      height: maxHeight,
      vertexFormat: VertexFormat.POSITION_ONLY,
      shadowVolume: true,
    });
  };

  Object.defineProperties(CorridorGeometry.prototype, {
    /**
     * @private
     */
    rectangle: {
      get: function () {
        if (!defined(this._rectangle)) {
          this._rectangle = computeRectangle$1(
            this._positions,
            this._ellipsoid,
            this._width,
            this._cornerType
          );
        }
        return this._rectangle;
      },
    },
    /**
     * For remapping texture coordinates when rendering CorridorGeometries as GroundPrimitives.
     *
     * Corridors don't support stRotation,
     * so just return the corners of the original system.
     * @private
     */
    textureCoordinateRotationPoints: {
      get: function () {
        return [0, 0, 0, 1, 1, 0];
      },
    },
  });

  var cartesian1$2 = new Cartesian3();
  var cartesian2$2 = new Cartesian3();
  var cartesian3$2 = new Cartesian3();

  function scaleToSurface$2(positions, ellipsoid) {
    for (var i = 0; i < positions.length; i++) {
      positions[i] = ellipsoid.scaleToGeodeticSurface(positions[i], positions[i]);
    }
    return positions;
  }

  function combine$2(computedPositions, cornerType) {
    var wallIndices = [];
    var positions = computedPositions.positions;
    var corners = computedPositions.corners;
    var endPositions = computedPositions.endPositions;
    var attributes = new GeometryAttributes();
    var corner;
    var leftCount = 0;
    var rightCount = 0;
    var i;
    var indicesLength = 0;
    var length;
    for (i = 0; i < positions.length; i += 2) {
      length = positions[i].length - 3;
      leftCount += length; //subtracting 3 to account for duplicate points at corners
      indicesLength += (length / 3) * 4;
      rightCount += positions[i + 1].length - 3;
    }
    leftCount += 3; //add back count for end positions
    rightCount += 3;
    for (i = 0; i < corners.length; i++) {
      corner = corners[i];
      var leftSide = corners[i].leftPositions;
      if (defined(leftSide)) {
        length = leftSide.length;
        leftCount += length;
        indicesLength += (length / 3) * 2;
      } else {
        length = corners[i].rightPositions.length;
        rightCount += length;
        indicesLength += (length / 3) * 2;
      }
    }

    var addEndPositions = defined(endPositions);
    var endPositionLength;
    if (addEndPositions) {
      endPositionLength = endPositions[0].length - 3;
      leftCount += endPositionLength;
      rightCount += endPositionLength;
      endPositionLength /= 3;
      indicesLength += endPositionLength * 4;
    }
    var size = leftCount + rightCount;
    var finalPositions = new Float64Array(size);
    var front = 0;
    var back = size - 1;
    var UL, LL, UR, LR;
    var rightPos, leftPos;
    var halfLength = endPositionLength / 2;

    var indices = IndexDatatype$1.createTypedArray(size / 3, indicesLength + 4);
    var index = 0;

    indices[index++] = front / 3;
    indices[index++] = (back - 2) / 3;
    if (addEndPositions) {
      // add rounded end
      wallIndices.push(front / 3);
      leftPos = cartesian1$2;
      rightPos = cartesian2$2;
      var firstEndPositions = endPositions[0];
      for (i = 0; i < halfLength; i++) {
        leftPos = Cartesian3.fromArray(
          firstEndPositions,
          (halfLength - 1 - i) * 3,
          leftPos
        );
        rightPos = Cartesian3.fromArray(
          firstEndPositions,
          (halfLength + i) * 3,
          rightPos
        );
        CorridorGeometryLibrary.addAttribute(finalPositions, rightPos, front);
        CorridorGeometryLibrary.addAttribute(
          finalPositions,
          leftPos,
          undefined,
          back
        );

        LL = front / 3;
        LR = LL + 1;
        UL = (back - 2) / 3;
        UR = UL - 1;
        indices[index++] = UL;
        indices[index++] = UR;
        indices[index++] = LL;
        indices[index++] = LR;

        front += 3;
        back -= 3;
      }
    }

    var posIndex = 0;
    var rightEdge = positions[posIndex++]; //add first two edges
    var leftEdge = positions[posIndex++];
    finalPositions.set(rightEdge, front);
    finalPositions.set(leftEdge, back - leftEdge.length + 1);

    length = leftEdge.length - 3;
    wallIndices.push(front / 3, (back - 2) / 3);
    for (i = 0; i < length; i += 3) {
      LL = front / 3;
      LR = LL + 1;
      UL = (back - 2) / 3;
      UR = UL - 1;
      indices[index++] = UL;
      indices[index++] = UR;
      indices[index++] = LL;
      indices[index++] = LR;

      front += 3;
      back -= 3;
    }

    for (i = 0; i < corners.length; i++) {
      var j;
      corner = corners[i];
      var l = corner.leftPositions;
      var r = corner.rightPositions;
      var start;
      var outsidePoint = cartesian3$2;
      if (defined(l)) {
        back -= 3;
        start = UR;
        wallIndices.push(LR);
        for (j = 0; j < l.length / 3; j++) {
          outsidePoint = Cartesian3.fromArray(l, j * 3, outsidePoint);
          indices[index++] = start - j - 1;
          indices[index++] = start - j;
          CorridorGeometryLibrary.addAttribute(
            finalPositions,
            outsidePoint,
            undefined,
            back
          );
          back -= 3;
        }
        wallIndices.push(start - Math.floor(l.length / 6));
        if (cornerType === CornerType$1.BEVELED) {
          wallIndices.push((back - 2) / 3 + 1);
        }
        front += 3;
      } else {
        front += 3;
        start = LR;
        wallIndices.push(UR);
        for (j = 0; j < r.length / 3; j++) {
          outsidePoint = Cartesian3.fromArray(r, j * 3, outsidePoint);
          indices[index++] = start + j;
          indices[index++] = start + j + 1;
          CorridorGeometryLibrary.addAttribute(
            finalPositions,
            outsidePoint,
            front
          );
          front += 3;
        }
        wallIndices.push(start + Math.floor(r.length / 6));
        if (cornerType === CornerType$1.BEVELED) {
          wallIndices.push(front / 3 - 1);
        }
        back -= 3;
      }
      rightEdge = positions[posIndex++];
      leftEdge = positions[posIndex++];
      rightEdge.splice(0, 3); //remove duplicate points added by corner
      leftEdge.splice(leftEdge.length - 3, 3);
      finalPositions.set(rightEdge, front);
      finalPositions.set(leftEdge, back - leftEdge.length + 1);
      length = leftEdge.length - 3;

      for (j = 0; j < leftEdge.length; j += 3) {
        LR = front / 3;
        LL = LR - 1;
        UR = (back - 2) / 3;
        UL = UR + 1;
        indices[index++] = UL;
        indices[index++] = UR;
        indices[index++] = LL;
        indices[index++] = LR;
        front += 3;
        back -= 3;
      }
      front -= 3;
      back += 3;
      wallIndices.push(front / 3, (back - 2) / 3);
    }

    if (addEndPositions) {
      // add rounded end
      front += 3;
      back -= 3;
      leftPos = cartesian1$2;
      rightPos = cartesian2$2;
      var lastEndPositions = endPositions[1];
      for (i = 0; i < halfLength; i++) {
        leftPos = Cartesian3.fromArray(
          lastEndPositions,
          (endPositionLength - i - 1) * 3,
          leftPos
        );
        rightPos = Cartesian3.fromArray(lastEndPositions, i * 3, rightPos);
        CorridorGeometryLibrary.addAttribute(
          finalPositions,
          leftPos,
          undefined,
          back
        );
        CorridorGeometryLibrary.addAttribute(finalPositions, rightPos, front);

        LR = front / 3;
        LL = LR - 1;
        UR = (back - 2) / 3;
        UL = UR + 1;
        indices[index++] = UL;
        indices[index++] = UR;
        indices[index++] = LL;
        indices[index++] = LR;

        front += 3;
        back -= 3;
      }

      wallIndices.push(front / 3);
    } else {
      wallIndices.push(front / 3, (back - 2) / 3);
    }
    indices[index++] = front / 3;
    indices[index++] = (back - 2) / 3;

    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: finalPositions,
    });

    return {
      attributes: attributes,
      indices: indices,
      wallIndices: wallIndices,
    };
  }

  function computePositionsExtruded$1(params) {
    var ellipsoid = params.ellipsoid;
    var computedPositions = CorridorGeometryLibrary.computePositions(params);
    var attr = combine$2(computedPositions, params.cornerType);
    var wallIndices = attr.wallIndices;
    var height = params.height;
    var extrudedHeight = params.extrudedHeight;
    var attributes = attr.attributes;
    var indices = attr.indices;
    var positions = attributes.position.values;
    var length = positions.length;
    var extrudedPositions = new Float64Array(length);
    extrudedPositions.set(positions);
    var newPositions = new Float64Array(length * 2);

    positions = PolygonPipeline.scaleToGeodeticHeight(
      positions,
      height,
      ellipsoid
    );
    extrudedPositions = PolygonPipeline.scaleToGeodeticHeight(
      extrudedPositions,
      extrudedHeight,
      ellipsoid
    );
    newPositions.set(positions);
    newPositions.set(extrudedPositions, length);
    attributes.position.values = newPositions;

    length /= 3;
    if (defined(params.offsetAttribute)) {
      var applyOffset = new Uint8Array(length * 2);
      if (params.offsetAttribute === GeometryOffsetAttribute$1.TOP) {
        applyOffset = arrayFill(applyOffset, 1, 0, length);
      } else {
        var applyOffsetValue =
          params.offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        applyOffset = arrayFill(applyOffset, applyOffsetValue);
      }

      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    var i;
    var iLength = indices.length;
    var newIndices = IndexDatatype$1.createTypedArray(
      newPositions.length / 3,
      (iLength + wallIndices.length) * 2
    );
    newIndices.set(indices);
    var index = iLength;
    for (i = 0; i < iLength; i += 2) {
      // bottom indices
      var v0 = indices[i];
      var v1 = indices[i + 1];
      newIndices[index++] = v0 + length;
      newIndices[index++] = v1 + length;
    }

    var UL, LL;
    for (i = 0; i < wallIndices.length; i++) {
      //wall indices
      UL = wallIndices[i];
      LL = UL + length;
      newIndices[index++] = UL;
      newIndices[index++] = LL;
    }

    return {
      attributes: attributes,
      indices: newIndices,
    };
  }

  /**
   * A description of a corridor outline.
   *
   * @alias CorridorOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that define the center of the corridor outline.
   * @param {Number} options.width The distance between the edges of the corridor outline.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number} [options.height=0] The distance in meters between the positions and the ellipsoid surface.
   * @param {Number} [options.extrudedHeight] The distance in meters between the extruded face and the ellipsoid surface.
   * @param {CornerType} [options.cornerType=CornerType.ROUNDED] Determines the style of the corners.
   *
   * @see CorridorOutlineGeometry.createGeometry
   *
   * @example
   * var corridor = new Cesium.CorridorOutlineGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArray([-72.0, 40.0, -70.0, 35.0]),
   *   width : 100000
   * });
   */
  function CorridorOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;
    var width = options.width;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options.positions", positions);
    Check.typeOf.number("options.width", width);
    //>>includeEnd('debug');

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    this._positions = positions;
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._width = width;
    this._height = Math.max(height, extrudedHeight);
    this._extrudedHeight = Math.min(height, extrudedHeight);
    this._cornerType = defaultValue(options.cornerType, CornerType$1.ROUNDED);
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createCorridorOutlineGeometry";

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      1 + positions.length * Cartesian3.packedLength + Ellipsoid.packedLength + 6;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CorridorOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CorridorOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.typeOf.object("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (var i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex++] = value._width;
    array[startingIndex++] = value._height;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._cornerType;
    array[startingIndex++] = value._granularity;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchEllipsoid$4 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchOptions$9 = {
    positions: undefined,
    ellipsoid: scratchEllipsoid$4,
    width: undefined,
    height: undefined,
    extrudedHeight: undefined,
    cornerType: undefined,
    granularity: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CorridorOutlineGeometry} [result] The object into which to store the result.
   * @returns {CorridorOutlineGeometry} The modified result parameter or a new CorridorOutlineGeometry instance if one was not provided.
   */
  CorridorOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (var i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$4);
    startingIndex += Ellipsoid.packedLength;

    var width = array[startingIndex++];
    var height = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var cornerType = array[startingIndex++];
    var granularity = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$9.positions = positions;
      scratchOptions$9.width = width;
      scratchOptions$9.height = height;
      scratchOptions$9.extrudedHeight = extrudedHeight;
      scratchOptions$9.cornerType = cornerType;
      scratchOptions$9.granularity = granularity;
      scratchOptions$9.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new CorridorOutlineGeometry(scratchOptions$9);
    }

    result._positions = positions;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._width = width;
    result._height = height;
    result._extrudedHeight = extrudedHeight;
    result._cornerType = cornerType;
    result._granularity = granularity;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of a corridor, including its vertices, indices, and a bounding sphere.
   *
   * @param {CorridorOutlineGeometry} corridorOutlineGeometry A description of the corridor.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CorridorOutlineGeometry.createGeometry = function (corridorOutlineGeometry) {
    var positions = corridorOutlineGeometry._positions;
    var width = corridorOutlineGeometry._width;
    var ellipsoid = corridorOutlineGeometry._ellipsoid;

    positions = scaleToSurface$2(positions, ellipsoid);
    var cleanPositions = arrayRemoveDuplicates(
      positions,
      Cartesian3.equalsEpsilon
    );

    if (cleanPositions.length < 2 || width <= 0) {
      return;
    }

    var height = corridorOutlineGeometry._height;
    var extrudedHeight = corridorOutlineGeometry._extrudedHeight;
    var extrude = !CesiumMath.equalsEpsilon(
      height,
      extrudedHeight,
      0,
      CesiumMath.EPSILON2
    );

    var params = {
      ellipsoid: ellipsoid,
      positions: cleanPositions,
      width: width,
      cornerType: corridorOutlineGeometry._cornerType,
      granularity: corridorOutlineGeometry._granularity,
      saveAttributes: false,
    };
    var attr;
    if (extrude) {
      params.height = height;
      params.extrudedHeight = extrudedHeight;
      params.offsetAttribute = corridorOutlineGeometry._offsetAttribute;
      attr = computePositionsExtruded$1(params);
    } else {
      var computedPositions = CorridorGeometryLibrary.computePositions(params);
      attr = combine$2(computedPositions, params.cornerType);
      attr.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
        attr.attributes.position.values,
        height,
        ellipsoid
      );

      if (defined(corridorOutlineGeometry._offsetAttribute)) {
        var length = attr.attributes.position.values.length;
        var applyOffset = new Uint8Array(length / 3);
        var offsetValue =
          corridorOutlineGeometry._offsetAttribute ===
          GeometryOffsetAttribute$1.NONE
            ? 0
            : 1;
        arrayFill(applyOffset, offsetValue);
        attr.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: applyOffset,
        });
      }
    }
    var attributes = attr.attributes;
    var boundingSphere = BoundingSphere.fromVertices(
      attributes.position.values,
      undefined,
      3
    );

    return new Geometry({
      attributes: attributes,
      indices: attr.indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: boundingSphere,
      offsetAttribute: corridorOutlineGeometry._offsetAttribute,
    });
  };

  /**
   * The culling volume defined by planes.
   *
   * @alias CullingVolume
   * @constructor
   *
   * @param {Cartesian4[]} [planes] An array of clipping planes.
   */
  function CullingVolume(planes) {
    /**
     * Each plane is represented by a Cartesian4 object, where the x, y, and z components
     * define the unit vector normal to the plane, and the w component is the distance of the
     * plane from the origin.
     * @type {Cartesian4[]}
     * @default []
     */
    this.planes = defaultValue(planes, []);
  }

  var faces = [new Cartesian3(), new Cartesian3(), new Cartesian3()];
  Cartesian3.clone(Cartesian3.UNIT_X, faces[0]);
  Cartesian3.clone(Cartesian3.UNIT_Y, faces[1]);
  Cartesian3.clone(Cartesian3.UNIT_Z, faces[2]);

  var scratchPlaneCenter = new Cartesian3();
  var scratchPlaneNormal$1 = new Cartesian3();
  var scratchPlane$1 = new Plane(new Cartesian3(1.0, 0.0, 0.0), 0.0);

  /**
   * Constructs a culling volume from a bounding sphere. Creates six planes that create a box containing the sphere.
   * The planes are aligned to the x, y, and z axes in world coordinates.
   *
   * @param {BoundingSphere} boundingSphere The bounding sphere used to create the culling volume.
   * @param {CullingVolume} [result] The object onto which to store the result.
   * @returns {CullingVolume} The culling volume created from the bounding sphere.
   */
  CullingVolume.fromBoundingSphere = function (boundingSphere, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingSphere)) {
      throw new DeveloperError("boundingSphere is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new CullingVolume();
    }

    var length = faces.length;
    var planes = result.planes;
    planes.length = 2 * length;

    var center = boundingSphere.center;
    var radius = boundingSphere.radius;

    var planeIndex = 0;

    for (var i = 0; i < length; ++i) {
      var faceNormal = faces[i];

      var plane0 = planes[planeIndex];
      var plane1 = planes[planeIndex + 1];

      if (!defined(plane0)) {
        plane0 = planes[planeIndex] = new Cartesian4();
      }
      if (!defined(plane1)) {
        plane1 = planes[planeIndex + 1] = new Cartesian4();
      }

      Cartesian3.multiplyByScalar(faceNormal, -radius, scratchPlaneCenter);
      Cartesian3.add(center, scratchPlaneCenter, scratchPlaneCenter);

      plane0.x = faceNormal.x;
      plane0.y = faceNormal.y;
      plane0.z = faceNormal.z;
      plane0.w = -Cartesian3.dot(faceNormal, scratchPlaneCenter);

      Cartesian3.multiplyByScalar(faceNormal, radius, scratchPlaneCenter);
      Cartesian3.add(center, scratchPlaneCenter, scratchPlaneCenter);

      plane1.x = -faceNormal.x;
      plane1.y = -faceNormal.y;
      plane1.z = -faceNormal.z;
      plane1.w = -Cartesian3.dot(
        Cartesian3.negate(faceNormal, scratchPlaneNormal$1),
        scratchPlaneCenter
      );

      planeIndex += 2;
    }

    return result;
  };

  /**
   * Determines whether a bounding volume intersects the culling volume.
   *
   * @param {Object} boundingVolume The bounding volume whose intersection with the culling volume is to be tested.
   * @returns {Intersect}  Intersect.OUTSIDE, Intersect.INTERSECTING, or Intersect.INSIDE.
   */
  CullingVolume.prototype.computeVisibility = function (boundingVolume) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingVolume)) {
      throw new DeveloperError("boundingVolume is required.");
    }
    //>>includeEnd('debug');

    var planes = this.planes;
    var intersecting = false;
    for (var k = 0, len = planes.length; k < len; ++k) {
      var result = boundingVolume.intersectPlane(
        Plane.fromCartesian4(planes[k], scratchPlane$1)
      );
      if (result === Intersect$1.OUTSIDE) {
        return Intersect$1.OUTSIDE;
      } else if (result === Intersect$1.INTERSECTING) {
        intersecting = true;
      }
    }

    return intersecting ? Intersect$1.INTERSECTING : Intersect$1.INSIDE;
  };

  /**
   * Determines whether a bounding volume intersects the culling volume.
   *
   * @param {Object} boundingVolume The bounding volume whose intersection with the culling volume is to be tested.
   * @param {Number} parentPlaneMask A bit mask from the boundingVolume's parent's check against the same culling
   *                                 volume, such that if (planeMask & (1 << planeIndex) === 0), for k < 31, then
   *                                 the parent (and therefore this) volume is completely inside plane[planeIndex]
   *                                 and that plane check can be skipped.
   * @returns {Number} A plane mask as described above (which can be applied to this boundingVolume's children).
   *
   * @private
   */
  CullingVolume.prototype.computeVisibilityWithPlaneMask = function (
    boundingVolume,
    parentPlaneMask
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingVolume)) {
      throw new DeveloperError("boundingVolume is required.");
    }
    if (!defined(parentPlaneMask)) {
      throw new DeveloperError("parentPlaneMask is required.");
    }
    //>>includeEnd('debug');

    if (
      parentPlaneMask === CullingVolume.MASK_OUTSIDE ||
      parentPlaneMask === CullingVolume.MASK_INSIDE
    ) {
      // parent is completely outside or completely inside, so this child is as well.
      return parentPlaneMask;
    }

    // Start with MASK_INSIDE (all zeros) so that after the loop, the return value can be compared with MASK_INSIDE.
    // (Because if there are fewer than 31 planes, the upper bits wont be changed.)
    var mask = CullingVolume.MASK_INSIDE;

    var planes = this.planes;
    for (var k = 0, len = planes.length; k < len; ++k) {
      // For k greater than 31 (since 31 is the maximum number of INSIDE/INTERSECTING bits we can store), skip the optimization.
      var flag = k < 31 ? 1 << k : 0;
      if (k < 31 && (parentPlaneMask & flag) === 0) {
        // boundingVolume is known to be INSIDE this plane.
        continue;
      }

      var result = boundingVolume.intersectPlane(
        Plane.fromCartesian4(planes[k], scratchPlane$1)
      );
      if (result === Intersect$1.OUTSIDE) {
        return CullingVolume.MASK_OUTSIDE;
      } else if (result === Intersect$1.INTERSECTING) {
        mask |= flag;
      }
    }

    return mask;
  };

  /**
   * For plane masks (as used in {@link CullingVolume#computeVisibilityWithPlaneMask}), this special value
   * represents the case where the object bounding volume is entirely outside the culling volume.
   *
   * @type {Number}
   * @private
   */
  CullingVolume.MASK_OUTSIDE = 0xffffffff;

  /**
   * For plane masks (as used in {@link CullingVolume.prototype.computeVisibilityWithPlaneMask}), this value
   * represents the case where the object bounding volume is entirely inside the culling volume.
   *
   * @type {Number}
   * @private
   */
  CullingVolume.MASK_INSIDE = 0x00000000;

  /**
   * For plane masks (as used in {@link CullingVolume.prototype.computeVisibilityWithPlaneMask}), this value
   * represents the case where the object bounding volume (may) intersect all planes of the culling volume.
   *
   * @type {Number}
   * @private
   */
  CullingVolume.MASK_INDETERMINATE = 0x7fffffff;

  /**
   * @private
   */
  var CylinderGeometryLibrary = {};

  /**
   * @private
   */
  CylinderGeometryLibrary.computePositions = function (
    length,
    topRadius,
    bottomRadius,
    slices,
    fill
  ) {
    var topZ = length * 0.5;
    var bottomZ = -topZ;

    var twoSlice = slices + slices;
    var size = fill ? 2 * twoSlice : twoSlice;
    var positions = new Float64Array(size * 3);
    var i;
    var index = 0;
    var tbIndex = 0;
    var bottomOffset = fill ? twoSlice * 3 : 0;
    var topOffset = fill ? (twoSlice + slices) * 3 : slices * 3;

    for (i = 0; i < slices; i++) {
      var angle = (i / slices) * CesiumMath.TWO_PI;
      var x = Math.cos(angle);
      var y = Math.sin(angle);
      var bottomX = x * bottomRadius;
      var bottomY = y * bottomRadius;
      var topX = x * topRadius;
      var topY = y * topRadius;

      positions[tbIndex + bottomOffset] = bottomX;
      positions[tbIndex + bottomOffset + 1] = bottomY;
      positions[tbIndex + bottomOffset + 2] = bottomZ;

      positions[tbIndex + topOffset] = topX;
      positions[tbIndex + topOffset + 1] = topY;
      positions[tbIndex + topOffset + 2] = topZ;
      tbIndex += 3;
      if (fill) {
        positions[index++] = bottomX;
        positions[index++] = bottomY;
        positions[index++] = bottomZ;
        positions[index++] = topX;
        positions[index++] = topY;
        positions[index++] = topZ;
      }
    }

    return positions;
  };

  var radiusScratch = new Cartesian2();
  var normalScratch$2 = new Cartesian3();
  var bitangentScratch = new Cartesian3();
  var tangentScratch = new Cartesian3();
  var positionScratch$1 = new Cartesian3();

  /**
   * A description of a cylinder.
   *
   * @alias CylinderGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number} options.length The length of the cylinder.
   * @param {Number} options.topRadius The radius of the top of the cylinder.
   * @param {Number} options.bottomRadius The radius of the bottom of the cylinder.
   * @param {Number} [options.slices=128] The number of edges around the perimeter of the cylinder.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @exception {DeveloperError} options.slices must be greater than or equal to 3.
   *
   * @see CylinderGeometry.createGeometry
   *
   * @example
   * // create cylinder geometry
   * var cylinder = new Cesium.CylinderGeometry({
   *     length: 200000,
   *     topRadius: 80000,
   *     bottomRadius: 200000,
   * });
   * var geometry = Cesium.CylinderGeometry.createGeometry(cylinder);
   */
  function CylinderGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var length = options.length;
    var topRadius = options.topRadius;
    var bottomRadius = options.bottomRadius;
    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);
    var slices = defaultValue(options.slices, 128);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(length)) {
      throw new DeveloperError("options.length must be defined.");
    }
    if (!defined(topRadius)) {
      throw new DeveloperError("options.topRadius must be defined.");
    }
    if (!defined(bottomRadius)) {
      throw new DeveloperError("options.bottomRadius must be defined.");
    }
    if (slices < 3) {
      throw new DeveloperError(
        "options.slices must be greater than or equal to 3."
      );
    }
    if (
      defined(options.offsetAttribute) &&
      options.offsetAttribute === GeometryOffsetAttribute$1.TOP
    ) {
      throw new DeveloperError(
        "GeometryOffsetAttribute.TOP is not a supported options.offsetAttribute for this geometry."
      );
    }
    //>>includeEnd('debug');

    this._length = length;
    this._topRadius = topRadius;
    this._bottomRadius = bottomRadius;
    this._vertexFormat = VertexFormat.clone(vertexFormat);
    this._slices = slices;
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createCylinderGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  CylinderGeometry.packedLength = VertexFormat.packedLength + 5;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CylinderGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CylinderGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._length;
    array[startingIndex++] = value._topRadius;
    array[startingIndex++] = value._bottomRadius;
    array[startingIndex++] = value._slices;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchVertexFormat$4 = new VertexFormat();
  var scratchOptions$a = {
    vertexFormat: scratchVertexFormat$4,
    length: undefined,
    topRadius: undefined,
    bottomRadius: undefined,
    slices: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CylinderGeometry} [result] The object into which to store the result.
   * @returns {CylinderGeometry} The modified result parameter or a new CylinderGeometry instance if one was not provided.
   */
  CylinderGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$4
    );
    startingIndex += VertexFormat.packedLength;

    var length = array[startingIndex++];
    var topRadius = array[startingIndex++];
    var bottomRadius = array[startingIndex++];
    var slices = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$a.length = length;
      scratchOptions$a.topRadius = topRadius;
      scratchOptions$a.bottomRadius = bottomRadius;
      scratchOptions$a.slices = slices;
      scratchOptions$a.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new CylinderGeometry(scratchOptions$a);
    }

    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._length = length;
    result._topRadius = topRadius;
    result._bottomRadius = bottomRadius;
    result._slices = slices;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of a cylinder, including its vertices, indices, and a bounding sphere.
   *
   * @param {CylinderGeometry} cylinderGeometry A description of the cylinder.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CylinderGeometry.createGeometry = function (cylinderGeometry) {
    var length = cylinderGeometry._length;
    var topRadius = cylinderGeometry._topRadius;
    var bottomRadius = cylinderGeometry._bottomRadius;
    var vertexFormat = cylinderGeometry._vertexFormat;
    var slices = cylinderGeometry._slices;

    if (
      length <= 0 ||
      topRadius < 0 ||
      bottomRadius < 0 ||
      (topRadius === 0 && bottomRadius === 0)
    ) {
      return;
    }

    var twoSlices = slices + slices;
    var threeSlices = slices + twoSlices;
    var numVertices = twoSlices + twoSlices;

    var positions = CylinderGeometryLibrary.computePositions(
      length,
      topRadius,
      bottomRadius,
      slices,
      true
    );

    var st = vertexFormat.st ? new Float32Array(numVertices * 2) : undefined;
    var normals = vertexFormat.normal
      ? new Float32Array(numVertices * 3)
      : undefined;
    var tangents = vertexFormat.tangent
      ? new Float32Array(numVertices * 3)
      : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(numVertices * 3)
      : undefined;

    var i;
    var computeNormal =
      vertexFormat.normal || vertexFormat.tangent || vertexFormat.bitangent;

    if (computeNormal) {
      var computeTangent = vertexFormat.tangent || vertexFormat.bitangent;

      var normalIndex = 0;
      var tangentIndex = 0;
      var bitangentIndex = 0;

      var theta = Math.atan2(bottomRadius - topRadius, length);
      var normal = normalScratch$2;
      normal.z = Math.sin(theta);
      var normalScale = Math.cos(theta);
      var tangent = tangentScratch;
      var bitangent = bitangentScratch;

      for (i = 0; i < slices; i++) {
        var angle = (i / slices) * CesiumMath.TWO_PI;
        var x = normalScale * Math.cos(angle);
        var y = normalScale * Math.sin(angle);
        if (computeNormal) {
          normal.x = x;
          normal.y = y;

          if (computeTangent) {
            tangent = Cartesian3.normalize(
              Cartesian3.cross(Cartesian3.UNIT_Z, normal, tangent),
              tangent
            );
          }

          if (vertexFormat.normal) {
            normals[normalIndex++] = normal.x;
            normals[normalIndex++] = normal.y;
            normals[normalIndex++] = normal.z;
            normals[normalIndex++] = normal.x;
            normals[normalIndex++] = normal.y;
            normals[normalIndex++] = normal.z;
          }

          if (vertexFormat.tangent) {
            tangents[tangentIndex++] = tangent.x;
            tangents[tangentIndex++] = tangent.y;
            tangents[tangentIndex++] = tangent.z;
            tangents[tangentIndex++] = tangent.x;
            tangents[tangentIndex++] = tangent.y;
            tangents[tangentIndex++] = tangent.z;
          }

          if (vertexFormat.bitangent) {
            bitangent = Cartesian3.normalize(
              Cartesian3.cross(normal, tangent, bitangent),
              bitangent
            );
            bitangents[bitangentIndex++] = bitangent.x;
            bitangents[bitangentIndex++] = bitangent.y;
            bitangents[bitangentIndex++] = bitangent.z;
            bitangents[bitangentIndex++] = bitangent.x;
            bitangents[bitangentIndex++] = bitangent.y;
            bitangents[bitangentIndex++] = bitangent.z;
          }
        }
      }

      for (i = 0; i < slices; i++) {
        if (vertexFormat.normal) {
          normals[normalIndex++] = 0;
          normals[normalIndex++] = 0;
          normals[normalIndex++] = -1;
        }
        if (vertexFormat.tangent) {
          tangents[tangentIndex++] = 1;
          tangents[tangentIndex++] = 0;
          tangents[tangentIndex++] = 0;
        }
        if (vertexFormat.bitangent) {
          bitangents[bitangentIndex++] = 0;
          bitangents[bitangentIndex++] = -1;
          bitangents[bitangentIndex++] = 0;
        }
      }

      for (i = 0; i < slices; i++) {
        if (vertexFormat.normal) {
          normals[normalIndex++] = 0;
          normals[normalIndex++] = 0;
          normals[normalIndex++] = 1;
        }
        if (vertexFormat.tangent) {
          tangents[tangentIndex++] = 1;
          tangents[tangentIndex++] = 0;
          tangents[tangentIndex++] = 0;
        }
        if (vertexFormat.bitangent) {
          bitangents[bitangentIndex++] = 0;
          bitangents[bitangentIndex++] = 1;
          bitangents[bitangentIndex++] = 0;
        }
      }
    }

    var numIndices = 12 * slices - 12;
    var indices = IndexDatatype$1.createTypedArray(numVertices, numIndices);
    var index = 0;
    var j = 0;
    for (i = 0; i < slices - 1; i++) {
      indices[index++] = j;
      indices[index++] = j + 2;
      indices[index++] = j + 3;

      indices[index++] = j;
      indices[index++] = j + 3;
      indices[index++] = j + 1;

      j += 2;
    }

    indices[index++] = twoSlices - 2;
    indices[index++] = 0;
    indices[index++] = 1;
    indices[index++] = twoSlices - 2;
    indices[index++] = 1;
    indices[index++] = twoSlices - 1;

    for (i = 1; i < slices - 1; i++) {
      indices[index++] = twoSlices + i + 1;
      indices[index++] = twoSlices + i;
      indices[index++] = twoSlices;
    }

    for (i = 1; i < slices - 1; i++) {
      indices[index++] = threeSlices;
      indices[index++] = threeSlices + i;
      indices[index++] = threeSlices + i + 1;
    }

    var textureCoordIndex = 0;
    if (vertexFormat.st) {
      var rad = Math.max(topRadius, bottomRadius);
      for (i = 0; i < numVertices; i++) {
        var position = Cartesian3.fromArray(positions, i * 3, positionScratch$1);
        st[textureCoordIndex++] = (position.x + rad) / (2.0 * rad);
        st[textureCoordIndex++] = (position.y + rad) / (2.0 * rad);
      }
    }

    var attributes = new GeometryAttributes();
    if (vertexFormat.position) {
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      });
    }

    if (vertexFormat.normal) {
      attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: normals,
      });
    }

    if (vertexFormat.tangent) {
      attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: tangents,
      });
    }

    if (vertexFormat.bitangent) {
      attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: bitangents,
      });
    }

    if (vertexFormat.st) {
      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: st,
      });
    }

    radiusScratch.x = length * 0.5;
    radiusScratch.y = Math.max(bottomRadius, topRadius);

    var boundingSphere = new BoundingSphere(
      Cartesian3.ZERO,
      Cartesian2.magnitude(radiusScratch)
    );

    if (defined(cylinderGeometry._offsetAttribute)) {
      length = positions.length;
      var applyOffset = new Uint8Array(length / 3);
      var offsetValue =
        cylinderGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
          ? 0
          : 1;
      arrayFill(applyOffset, offsetValue);
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: boundingSphere,
      offsetAttribute: cylinderGeometry._offsetAttribute,
    });
  };

  var unitCylinderGeometry;

  /**
   * Returns the geometric representation of a unit cylinder, including its vertices, indices, and a bounding sphere.
   * @returns {Geometry} The computed vertices and indices.
   *
   * @private
   */
  CylinderGeometry.getUnitCylinder = function () {
    if (!defined(unitCylinderGeometry)) {
      unitCylinderGeometry = CylinderGeometry.createGeometry(
        new CylinderGeometry({
          topRadius: 1.0,
          bottomRadius: 1.0,
          length: 1.0,
          vertexFormat: VertexFormat.POSITION_ONLY,
        })
      );
    }
    return unitCylinderGeometry;
  };

  var radiusScratch$1 = new Cartesian2();

  /**
   * A description of the outline of a cylinder.
   *
   * @alias CylinderOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number} options.length The length of the cylinder.
   * @param {Number} options.topRadius The radius of the top of the cylinder.
   * @param {Number} options.bottomRadius The radius of the bottom of the cylinder.
   * @param {Number} [options.slices=128] The number of edges around the perimeter of the cylinder.
   * @param {Number} [options.numberOfVerticalLines=16] Number of lines to draw between the top and bottom surfaces of the cylinder.
   *
   * @exception {DeveloperError} options.length must be greater than 0.
   * @exception {DeveloperError} options.topRadius must be greater than 0.
   * @exception {DeveloperError} options.bottomRadius must be greater than 0.
   * @exception {DeveloperError} bottomRadius and topRadius cannot both equal 0.
   * @exception {DeveloperError} options.slices must be greater than or equal to 3.
   *
   * @see CylinderOutlineGeometry.createGeometry
   *
   * @example
   * // create cylinder geometry
   * var cylinder = new Cesium.CylinderOutlineGeometry({
   *     length: 200000,
   *     topRadius: 80000,
   *     bottomRadius: 200000,
   * });
   * var geometry = Cesium.CylinderOutlineGeometry.createGeometry(cylinder);
   */
  function CylinderOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var length = options.length;
    var topRadius = options.topRadius;
    var bottomRadius = options.bottomRadius;
    var slices = defaultValue(options.slices, 128);
    var numberOfVerticalLines = Math.max(
      defaultValue(options.numberOfVerticalLines, 16),
      0
    );

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("options.positions", length);
    Check.typeOf.number("options.topRadius", topRadius);
    Check.typeOf.number("options.bottomRadius", bottomRadius);
    Check.typeOf.number.greaterThanOrEquals("options.slices", slices, 3);
    if (
      defined(options.offsetAttribute) &&
      options.offsetAttribute === GeometryOffsetAttribute$1.TOP
    ) {
      throw new DeveloperError(
        "GeometryOffsetAttribute.TOP is not a supported options.offsetAttribute for this geometry."
      );
    }
    //>>includeEnd('debug');

    this._length = length;
    this._topRadius = topRadius;
    this._bottomRadius = bottomRadius;
    this._slices = slices;
    this._numberOfVerticalLines = numberOfVerticalLines;
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createCylinderOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  CylinderOutlineGeometry.packedLength = 6;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {CylinderOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  CylinderOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value._length;
    array[startingIndex++] = value._topRadius;
    array[startingIndex++] = value._bottomRadius;
    array[startingIndex++] = value._slices;
    array[startingIndex++] = value._numberOfVerticalLines;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchOptions$b = {
    length: undefined,
    topRadius: undefined,
    bottomRadius: undefined,
    slices: undefined,
    numberOfVerticalLines: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {CylinderOutlineGeometry} [result] The object into which to store the result.
   * @returns {CylinderOutlineGeometry} The modified result parameter or a new CylinderOutlineGeometry instance if one was not provided.
   */
  CylinderOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var length = array[startingIndex++];
    var topRadius = array[startingIndex++];
    var bottomRadius = array[startingIndex++];
    var slices = array[startingIndex++];
    var numberOfVerticalLines = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$b.length = length;
      scratchOptions$b.topRadius = topRadius;
      scratchOptions$b.bottomRadius = bottomRadius;
      scratchOptions$b.slices = slices;
      scratchOptions$b.numberOfVerticalLines = numberOfVerticalLines;
      scratchOptions$b.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new CylinderOutlineGeometry(scratchOptions$b);
    }

    result._length = length;
    result._topRadius = topRadius;
    result._bottomRadius = bottomRadius;
    result._slices = slices;
    result._numberOfVerticalLines = numberOfVerticalLines;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of an outline of a cylinder, including its vertices, indices, and a bounding sphere.
   *
   * @param {CylinderOutlineGeometry} cylinderGeometry A description of the cylinder outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  CylinderOutlineGeometry.createGeometry = function (cylinderGeometry) {
    var length = cylinderGeometry._length;
    var topRadius = cylinderGeometry._topRadius;
    var bottomRadius = cylinderGeometry._bottomRadius;
    var slices = cylinderGeometry._slices;
    var numberOfVerticalLines = cylinderGeometry._numberOfVerticalLines;

    if (
      length <= 0 ||
      topRadius < 0 ||
      bottomRadius < 0 ||
      (topRadius === 0 && bottomRadius === 0)
    ) {
      return;
    }

    var numVertices = slices * 2;

    var positions = CylinderGeometryLibrary.computePositions(
      length,
      topRadius,
      bottomRadius,
      slices,
      false
    );
    var numIndices = slices * 2;
    var numSide;
    if (numberOfVerticalLines > 0) {
      var numSideLines = Math.min(numberOfVerticalLines, slices);
      numSide = Math.round(slices / numSideLines);
      numIndices += numSideLines;
    }

    var indices = IndexDatatype$1.createTypedArray(numVertices, numIndices * 2);
    var index = 0;
    var i;
    for (i = 0; i < slices - 1; i++) {
      indices[index++] = i;
      indices[index++] = i + 1;
      indices[index++] = i + slices;
      indices[index++] = i + 1 + slices;
    }

    indices[index++] = slices - 1;
    indices[index++] = 0;
    indices[index++] = slices + slices - 1;
    indices[index++] = slices;

    if (numberOfVerticalLines > 0) {
      for (i = 0; i < slices; i += numSide) {
        indices[index++] = i;
        indices[index++] = i + slices;
      }
    }

    var attributes = new GeometryAttributes();
    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: positions,
    });

    radiusScratch$1.x = length * 0.5;
    radiusScratch$1.y = Math.max(bottomRadius, topRadius);

    var boundingSphere = new BoundingSphere(
      Cartesian3.ZERO,
      Cartesian2.magnitude(radiusScratch$1)
    );

    if (defined(cylinderGeometry._offsetAttribute)) {
      length = positions.length;
      var applyOffset = new Uint8Array(length / 3);
      var offsetValue =
        cylinderGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
          ? 0
          : 1;
      arrayFill(applyOffset, offsetValue);
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: boundingSphere,
      offsetAttribute: cylinderGeometry._offsetAttribute,
    });
  };

  /**
   * A simple proxy that appends the desired resource as the sole query parameter
   * to the given proxy URL.
   *
   * @alias DefaultProxy
   * @constructor
   * @extends {Proxy}
   *
   * @param {String} proxy The proxy URL that will be used to requests all resources.
   */
  function DefaultProxy(proxy) {
    this.proxy = proxy;
  }

  /**
   * Get the final URL to use to request a given resource.
   *
   * @param {String} resource The resource to request.
   * @returns {String} proxied resource
   */
  DefaultProxy.prototype.getURL = function (resource) {
    var prefix = this.proxy.indexOf("?") === -1 ? "?" : "";
    return this.proxy + prefix + encodeURIComponent(resource);
  };

  /**
   * Determines visibility based on the distance to the camera.
   *
   * @alias DistanceDisplayCondition
   * @constructor
   *
   * @param {Number} [near=0.0] The smallest distance in the interval where the object is visible.
   * @param {Number} [far=Number.MAX_VALUE] The largest distance in the interval where the object is visible.
   *
   * @example
   * // Make a billboard that is only visible when the distance to the camera is between 10 and 20 meters.
   * billboard.distanceDisplayCondition = new Cesium.DistanceDisplayCondition(10.0, 20.0);
   */
  function DistanceDisplayCondition(near, far) {
    near = defaultValue(near, 0.0);
    this._near = near;

    far = defaultValue(far, Number.MAX_VALUE);
    this._far = far;
  }

  Object.defineProperties(DistanceDisplayCondition.prototype, {
    /**
     * The smallest distance in the interval where the object is visible.
     * @memberof DistanceDisplayCondition.prototype
     * @type {Number}
     * @default 0.0
     */
    near: {
      get: function () {
        return this._near;
      },
      set: function (value) {
        this._near = value;
      },
    },
    /**
     * The largest distance in the interval where the object is visible.
     * @memberof DistanceDisplayCondition.prototype
     * @type {Number}
     * @default Number.MAX_VALUE
     */
    far: {
      get: function () {
        return this._far;
      },
      set: function (value) {
        this._far = value;
      },
    },
  });

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  DistanceDisplayCondition.packedLength = 2;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {DistanceDisplayCondition} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  DistanceDisplayCondition.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.near;
    array[startingIndex] = value.far;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {DistanceDisplayCondition} [result] The object into which to store the result.
   * @returns {DistanceDisplayCondition} The modified result parameter or a new DistanceDisplayCondition instance if one was not provided.
   */
  DistanceDisplayCondition.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new DistanceDisplayCondition();
    }
    result.near = array[startingIndex++];
    result.far = array[startingIndex];
    return result;
  };

  /**
   * Determines if two distance display conditions are equal.
   *
   * @param {DistanceDisplayCondition} left A distance display condition.
   * @param {DistanceDisplayCondition} right Another distance display condition.
   * @return {Boolean} Whether the two distance display conditions are equal.
   */
  DistanceDisplayCondition.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.near === right.near &&
        left.far === right.far)
    );
  };

  /**
   * Duplicates a distance display condition instance.
   *
   * @param {DistanceDisplayCondition} [value] The distance display condition to duplicate.
   * @param {DistanceDisplayCondition} [result] The result onto which to store the result.
   * @return {DistanceDisplayCondition} The duplicated instance.
   */
  DistanceDisplayCondition.clone = function (value, result) {
    if (!defined(value)) {
      return undefined;
    }

    if (!defined(result)) {
      result = new DistanceDisplayCondition();
    }

    result.near = value.near;
    result.far = value.far;
    return result;
  };

  /**
   * Duplicates this instance.
   *
   * @param {DistanceDisplayCondition} [result] The result onto which to store the result.
   * @return {DistanceDisplayCondition} The duplicated instance.
   */
  DistanceDisplayCondition.prototype.clone = function (result) {
    return DistanceDisplayCondition.clone(this, result);
  };

  /**
   * Determines if this distance display condition is equal to another.
   *
   * @param {DistanceDisplayCondition} other Another distance display condition.
   * @return {Boolean} Whether this distance display condition is equal to the other.
   */
  DistanceDisplayCondition.prototype.equals = function (other) {
    return DistanceDisplayCondition.equals(this, other);
  };

  /**
   * Value and type information for per-instance geometry attribute that determines if the geometry instance has a distance display condition.
   *
   * @alias DistanceDisplayConditionGeometryInstanceAttribute
   * @constructor
   *
   * @param {Number} [near=0.0] The near distance.
   * @param {Number} [far=Number.MAX_VALUE] The far distance.
   *
   * @exception {DeveloperError} far must be greater than near.
   *
   * @example
   * var instance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.BoxGeometry({
   *     vertexFormat : Cesium.VertexFormat.POSITION_AND_NORMAL,
   *     minimum : new Cesium.Cartesian3(-250000.0, -250000.0, -250000.0),
   *     maximum : new Cesium.Cartesian3(250000.0, 250000.0, 250000.0)
   *   }),
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 1000000.0), new Cesium.Matrix4()),
   *   id : 'box',
   *   attributes : {
   *     distanceDisplayCondition : new Cesium.DistanceDisplayConditionGeometryInstanceAttribute(100.0, 10000.0)
   *   }
   * });
   *
   * @see GeometryInstance
   * @see GeometryInstanceAttribute
   */
  function DistanceDisplayConditionGeometryInstanceAttribute(near, far) {
    near = defaultValue(near, 0.0);
    far = defaultValue(far, Number.MAX_VALUE);

    //>>includeStart('debug', pragmas.debug);
    if (far <= near) {
      throw new DeveloperError(
        "far distance must be greater than near distance."
      );
    }
    //>>includeEnd('debug');

    /**
     * The values for the attributes stored in a typed array.
     *
     * @type Float32Array
     *
     * @default [0.0, 0.0, Number.MAX_VALUE]
     */
    this.value = new Float32Array([near, far]);
  }

  Object.defineProperties(
    DistanceDisplayConditionGeometryInstanceAttribute.prototype,
    {
      /**
       * The datatype of each component in the attribute, e.g., individual elements in
       * {@link DistanceDisplayConditionGeometryInstanceAttribute#value}.
       *
       * @memberof DistanceDisplayConditionGeometryInstanceAttribute.prototype
       *
       * @type {ComponentDatatype}
       * @readonly
       *
       * @default {@link ComponentDatatype.FLOAT}
       */
      componentDatatype: {
        get: function () {
          return ComponentDatatype$1.FLOAT;
        },
      },

      /**
       * The number of components in the attributes, i.e., {@link DistanceDisplayConditionGeometryInstanceAttribute#value}.
       *
       * @memberof DistanceDisplayConditionGeometryInstanceAttribute.prototype
       *
       * @type {Number}
       * @readonly
       *
       * @default 3
       */
      componentsPerAttribute: {
        get: function () {
          return 2;
        },
      },

      /**
       * When <code>true</code> and <code>componentDatatype</code> is an integer format,
       * indicate that the components should be mapped to the range [0, 1] (unsigned)
       * or [-1, 1] (signed) when they are accessed as floating-point for rendering.
       *
       * @memberof DistanceDisplayConditionGeometryInstanceAttribute.prototype
       *
       * @type {Boolean}
       * @readonly
       *
       * @default false
       */
      normalize: {
        get: function () {
          return false;
        },
      },
    }
  );

  /**
   * Creates a new {@link DistanceDisplayConditionGeometryInstanceAttribute} instance given the provided an enabled flag and {@link DistanceDisplayCondition}.
   *
   * @param {DistanceDisplayCondition} distanceDisplayCondition The distance display condition.
   * @returns {DistanceDisplayConditionGeometryInstanceAttribute} The new {@link DistanceDisplayConditionGeometryInstanceAttribute} instance.
   *
   * @exception {DeveloperError} distanceDisplayCondition.far must be greater than distanceDisplayCondition.near
   *
   * @example
   * var distanceDisplayCondition = new Cesium.DistanceDisplayCondition(100.0, 10000.0);
   * var instance = new Cesium.GeometryInstance({
   *   geometry : geometry,
   *   attributes : {
   *     distanceDisplayCondition : Cesium.DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(distanceDisplayCondition)
   *   }
   * });
   */
  DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition = function (
    distanceDisplayCondition
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(distanceDisplayCondition)) {
      throw new DeveloperError("distanceDisplayCondition is required.");
    }
    if (distanceDisplayCondition.far <= distanceDisplayCondition.near) {
      throw new DeveloperError(
        "distanceDisplayCondition.far distance must be greater than distanceDisplayCondition.near distance."
      );
    }
    //>>includeEnd('debug');

    return new DistanceDisplayConditionGeometryInstanceAttribute(
      distanceDisplayCondition.near,
      distanceDisplayCondition.far
    );
  };

  /**
   * Converts a distance display condition to a typed array that can be used to assign a distance display condition attribute.
   *
   * @param {DistanceDisplayCondition} distanceDisplayCondition The distance display condition value.
   * @param {Float32Array} [result] The array to store the result in, if undefined a new instance will be created.
   * @returns {Float32Array} The modified result parameter or a new instance if result was undefined.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.distanceDisplayCondition = Cesium.DistanceDisplayConditionGeometryInstanceAttribute.toValue(distanceDisplayCondition, attributes.distanceDisplayCondition);
   */
  DistanceDisplayConditionGeometryInstanceAttribute.toValue = function (
    distanceDisplayCondition,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(distanceDisplayCondition)) {
      throw new DeveloperError("distanceDisplayCondition is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Float32Array([
        distanceDisplayCondition.near,
        distanceDisplayCondition.far,
      ]);
    }
    result[0] = distanceDisplayCondition.near;
    result[1] = distanceDisplayCondition.far;
    return result;
  };

  /**
   * @private
   */
  function DoublyLinkedList() {
    this.head = undefined;
    this.tail = undefined;
    this._length = 0;
  }

  Object.defineProperties(DoublyLinkedList.prototype, {
    length: {
      get: function () {
        return this._length;
      },
    },
  });

  /**
   * @private
   */
  function DoublyLinkedListNode(item, previous, next) {
    this.item = item;
    this.previous = previous;
    this.next = next;
  }

  /**
   * Adds the item to the end of the list
   * @param {*} [item]
   * @return {DoublyLinkedListNode}
   */
  DoublyLinkedList.prototype.add = function (item) {
    var node = new DoublyLinkedListNode(item, this.tail, undefined);

    if (defined(this.tail)) {
      this.tail.next = node;
      this.tail = node;
    } else {
      this.head = node;
      this.tail = node;
    }

    ++this._length;

    return node;
  };

  function remove(list, node) {
    if (defined(node.previous) && defined(node.next)) {
      node.previous.next = node.next;
      node.next.previous = node.previous;
    } else if (defined(node.previous)) {
      // Remove last node
      node.previous.next = undefined;
      list.tail = node.previous;
    } else if (defined(node.next)) {
      // Remove first node
      node.next.previous = undefined;
      list.head = node.next;
    } else {
      // Remove last node in the linked list
      list.head = undefined;
      list.tail = undefined;
    }

    node.next = undefined;
    node.previous = undefined;
  }

  /**
   * Removes the given node from the list
   * @param {DoublyLinkedListNode} node
   */
  DoublyLinkedList.prototype.remove = function (node) {
    if (!defined(node)) {
      return;
    }

    remove(this, node);

    --this._length;
  };

  /**
   * Moves nextNode after node
   * @param {DoublyLinkedListNode} node
   * @param {DoublyLinkedListNode} nextNode
   */
  DoublyLinkedList.prototype.splice = function (node, nextNode) {
    if (node === nextNode) {
      return;
    }

    // Remove nextNode, then insert after node
    remove(this, nextNode);

    var oldNodeNext = node.next;
    node.next = nextNode;

    // nextNode is the new tail
    if (this.tail === node) {
      this.tail = nextNode;
    } else {
      oldNodeNext.previous = nextNode;
    }

    nextNode.next = oldNodeNext;
    nextNode.previous = node;
  };

  /**
  @license
  tween.js - https://github.com/sole/tween.js

  Copyright (c) 2010-2012 Tween.js authors.

  Easing equations Copyright (c) 2001 Robert Penner http://robertpenner.com/easing/

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  */

  /**
   * @author sole / http://soledadpenades.com
   * @author mrdoob / http://mrdoob.com
   * @author Robert Eisele / http://www.xarg.org
   * @author Philippe / http://philippe.elsass.me
   * @author Robert Penner / http://www.robertpenner.com/easing_terms_of_use.html
   * @author Paul Lewis / http://www.aerotwist.com/
   * @author lechecacharro
   * @author Josh Faul / http://jocafa.com/
   * @author egraether / http://egraether.com/
   * @author endel / http://endel.me
   * @author Ben Delarre / http://delarre.net
   */

      // Date.now shim for (ahem) Internet Explo(d|r)er
      if ( Date.now === undefined ) {

          Date.now = function () {

              return new Date().valueOf();

          };

      }

      var TWEEN = TWEEN || ( function () {

          var _tweens = [];

          return {

              REVISION: '13',

              getAll: function () {

                  return _tweens;

              },

              removeAll: function () {

                  _tweens = [];

              },

              add: function ( tween ) {

                  _tweens.push( tween );

              },

              remove: function ( tween ) {

                  var i = _tweens.indexOf( tween );

                  if ( i !== -1 ) {

                      _tweens.splice( i, 1 );

                  }

              },

              update: function ( time ) {

                  if ( _tweens.length === 0 ) return false;

                  var i = 0;

                  time = time !== undefined ? time : ( typeof window !== 'undefined' && window.performance !== undefined && window.performance.now !== undefined ? window.performance.now() : Date.now() );

                  while ( i < _tweens.length ) {

                      if ( _tweens[ i ].update( time ) ) {

                          i++;

                      } else {

                          _tweens.splice( i, 1 );

                      }

                  }

                  return true;

              }
          };

      } )();

      TWEEN.Tween = function ( object ) {

          var _object = object;
          var _valuesStart = {};
          var _valuesEnd = {};
          var _valuesStartRepeat = {};
          var _duration = 1000;
          var _repeat = 0;
          var _yoyo = false;
          var _isPlaying = false;
          var _delayTime = 0;
          var _startTime = null;
          var _easingFunction = TWEEN.Easing.Linear.None;
          var _interpolationFunction = TWEEN.Interpolation.Linear;
          var _chainedTweens = [];
          var _onStartCallback = null;
          var _onStartCallbackFired = false;
          var _onUpdateCallback = null;
          var _onCompleteCallback = null;
          var _onStopCallback = null;

          // Set all starting values present on the target object
          for ( var field in object ) {

              _valuesStart[ field ] = parseFloat(object[field], 10);

          }

          this.to = function ( properties, duration ) {

              if ( duration !== undefined ) {

                  _duration = duration;

              }

              _valuesEnd = properties;

              return this;

          };

          this.start = function ( time ) {

              TWEEN.add( this );

              _isPlaying = true;

              _onStartCallbackFired = false;

              _startTime = time !== undefined ? time : ( typeof window !== 'undefined' && window.performance !== undefined && window.performance.now !== undefined ? window.performance.now() : Date.now() );
              _startTime += _delayTime;

              for ( var property in _valuesEnd ) {

                  // check if an Array was provided as property value
                  if ( _valuesEnd[ property ] instanceof Array ) {

                      if ( _valuesEnd[ property ].length === 0 ) {

                          continue;

                      }

                      // create a local copy of the Array with the start value at the front
                      _valuesEnd[ property ] = [ _object[ property ] ].concat( _valuesEnd[ property ] );

                  }

                  _valuesStart[ property ] = _object[ property ];

                  if( ( _valuesStart[ property ] instanceof Array ) === false ) {
                      _valuesStart[ property ] *= 1.0; // Ensures we're using numbers, not strings
                  }

                  _valuesStartRepeat[ property ] = _valuesStart[ property ] || 0;

              }

              return this;

          };

          this.stop = function () {

              if ( !_isPlaying ) {
                  return this;
              }

              TWEEN.remove( this );
              _isPlaying = false;

              if ( _onStopCallback !== null ) {

                  _onStopCallback.call( _object );

              }

              this.stopChainedTweens();
              return this;

          };

          this.stopChainedTweens = function () {

              for ( var i = 0, numChainedTweens = _chainedTweens.length; i < numChainedTweens; i++ ) {

                  _chainedTweens[ i ].stop();

              }

          };

          this.delay = function ( amount ) {

              _delayTime = amount;
              return this;

          };

          this.repeat = function ( times ) {

              _repeat = times;
              return this;

          };

          this.yoyo = function( yoyo ) {

              _yoyo = yoyo;
              return this;

          };


          this.easing = function ( easing ) {

              _easingFunction = easing;
              return this;

          };

          this.interpolation = function ( interpolation ) {

              _interpolationFunction = interpolation;
              return this;

          };

          this.chain = function () {

              _chainedTweens = arguments;
              return this;

          };

          this.onStart = function ( callback ) {

              _onStartCallback = callback;
              return this;

          };

          this.onUpdate = function ( callback ) {

              _onUpdateCallback = callback;
              return this;

          };

          this.onComplete = function ( callback ) {

              _onCompleteCallback = callback;
              return this;

          };

          this.onStop = function ( callback ) {

              _onStopCallback = callback;
              return this;

          };

          this.update = function ( time ) {

              var property;

              if ( time < _startTime ) {

                  return true;

              }

              if ( _onStartCallbackFired === false ) {

                  if ( _onStartCallback !== null ) {

                      _onStartCallback.call( _object );

                  }

                  _onStartCallbackFired = true;

              }

              var elapsed = ( time - _startTime ) / _duration;
              elapsed = elapsed > 1 ? 1 : elapsed;

              var value = _easingFunction( elapsed );

              for ( property in _valuesEnd ) {

                  var start = _valuesStart[ property ] || 0;
                  var end = _valuesEnd[ property ];

                  if ( end instanceof Array ) {

                      _object[ property ] = _interpolationFunction( end, value );

                  } else {

                      // Parses relative end values with start as base (e.g.: +10, -3)
                      if ( typeof(end) === "string" ) {
                          end = start + parseFloat(end, 10);
                      }

                      // protect against non numeric properties.
                      if ( typeof(end) === "number" ) {
                          _object[ property ] = start + ( end - start ) * value;
                      }

                  }

              }

              if ( _onUpdateCallback !== null ) {

                  _onUpdateCallback.call( _object, value );

              }

              if ( elapsed == 1 ) {

                  if ( _repeat > 0 ) {

                      if( isFinite( _repeat ) ) {
                          _repeat--;
                      }

                      // reassign starting values, restart by making startTime = now
                      for( property in _valuesStartRepeat ) {

                          if ( typeof( _valuesEnd[ property ] ) === "string" ) {
                              _valuesStartRepeat[ property ] = _valuesStartRepeat[ property ] + parseFloat(_valuesEnd[ property ], 10);
                          }

                          if (_yoyo) {
                              var tmp = _valuesStartRepeat[ property ];
                              _valuesStartRepeat[ property ] = _valuesEnd[ property ];
                              _valuesEnd[ property ] = tmp;
                          }

                          _valuesStart[ property ] = _valuesStartRepeat[ property ];

                      }

                      _startTime = time + _delayTime;

                      return true;

                  } else {

                      if ( _onCompleteCallback !== null ) {

                          _onCompleteCallback.call( _object );

                      }

                      for ( var i = 0, numChainedTweens = _chainedTweens.length; i < numChainedTweens; i++ ) {

                          _chainedTweens[ i ].start( time );

                      }

                      return false;

                  }

              }

              return true;

          };

      };


      TWEEN.Easing = {

          Linear: {

              None: function ( k ) {

                  return k;

              }

          },

          Quadratic: {

              In: function ( k ) {

                  return k * k;

              },

              Out: function ( k ) {

                  return k * ( 2 - k );

              },

              InOut: function ( k ) {

                  if ( ( k *= 2 ) < 1 ) return 0.5 * k * k;
                  return - 0.5 * ( --k * ( k - 2 ) - 1 );

              }

          },

          Cubic: {

              In: function ( k ) {

                  return k * k * k;

              },

              Out: function ( k ) {

                  return --k * k * k + 1;

              },

              InOut: function ( k ) {

                  if ( ( k *= 2 ) < 1 ) return 0.5 * k * k * k;
                  return 0.5 * ( ( k -= 2 ) * k * k + 2 );

              }

          },

          Quartic: {

              In: function ( k ) {

                  return k * k * k * k;

              },

              Out: function ( k ) {

                  return 1 - ( --k * k * k * k );

              },

              InOut: function ( k ) {

                  if ( ( k *= 2 ) < 1) return 0.5 * k * k * k * k;
                  return - 0.5 * ( ( k -= 2 ) * k * k * k - 2 );

              }

          },

          Quintic: {

              In: function ( k ) {

                  return k * k * k * k * k;

              },

              Out: function ( k ) {

                  return --k * k * k * k * k + 1;

              },

              InOut: function ( k ) {

                  if ( ( k *= 2 ) < 1 ) return 0.5 * k * k * k * k * k;
                  return 0.5 * ( ( k -= 2 ) * k * k * k * k + 2 );

              }

          },

          Sinusoidal: {

              In: function ( k ) {

                  return 1 - Math.cos( k * Math.PI / 2 );

              },

              Out: function ( k ) {

                  return Math.sin( k * Math.PI / 2 );

              },

              InOut: function ( k ) {

                  return 0.5 * ( 1 - Math.cos( Math.PI * k ) );

              }

          },

          Exponential: {

              In: function ( k ) {

                  return k === 0 ? 0 : Math.pow( 1024, k - 1 );

              },

              Out: function ( k ) {

                  return k === 1 ? 1 : 1 - Math.pow( 2, - 10 * k );

              },

              InOut: function ( k ) {

                  if ( k === 0 ) return 0;
                  if ( k === 1 ) return 1;
                  if ( ( k *= 2 ) < 1 ) return 0.5 * Math.pow( 1024, k - 1 );
                  return 0.5 * ( - Math.pow( 2, - 10 * ( k - 1 ) ) + 2 );

              }

          },

          Circular: {

              In: function ( k ) {

                  return 1 - Math.sqrt( 1 - k * k );

              },

              Out: function ( k ) {

                  return Math.sqrt( 1 - ( --k * k ) );

              },

              InOut: function ( k ) {

                  if ( ( k *= 2 ) < 1) return - 0.5 * ( Math.sqrt( 1 - k * k) - 1);
                  return 0.5 * ( Math.sqrt( 1 - ( k -= 2) * k) + 1);

              }

          },

          Elastic: {

              In: function ( k ) {

                  var s, a = 0.1, p = 0.4;
                  if ( k === 0 ) return 0;
                  if ( k === 1 ) return 1;
                  if ( !a || a < 1 ) { a = 1; s = p / 4; }
                  else s = p * Math.asin( 1 / a ) / ( 2 * Math.PI );
                  return - ( a * Math.pow( 2, 10 * ( k -= 1 ) ) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) );

              },

              Out: function ( k ) {

                  var s, a = 0.1, p = 0.4;
                  if ( k === 0 ) return 0;
                  if ( k === 1 ) return 1;
                  if ( !a || a < 1 ) { a = 1; s = p / 4; }
                  else s = p * Math.asin( 1 / a ) / ( 2 * Math.PI );
                  return ( a * Math.pow( 2, - 10 * k) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) + 1 );

              },

              InOut: function ( k ) {

                  var s, a = 0.1, p = 0.4;
                  if ( k === 0 ) return 0;
                  if ( k === 1 ) return 1;
                  if ( !a || a < 1 ) { a = 1; s = p / 4; }
                  else s = p * Math.asin( 1 / a ) / ( 2 * Math.PI );
                  if ( ( k *= 2 ) < 1 ) return - 0.5 * ( a * Math.pow( 2, 10 * ( k -= 1 ) ) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) );
                  return a * Math.pow( 2, -10 * ( k -= 1 ) ) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) * 0.5 + 1;

              }

          },

          Back: {

              In: function ( k ) {

                  var s = 1.70158;
                  return k * k * ( ( s + 1 ) * k - s );

              },

              Out: function ( k ) {

                  var s = 1.70158;
                  return --k * k * ( ( s + 1 ) * k + s ) + 1;

              },

              InOut: function ( k ) {

                  var s = 1.70158 * 1.525;
                  if ( ( k *= 2 ) < 1 ) return 0.5 * ( k * k * ( ( s + 1 ) * k - s ) );
                  return 0.5 * ( ( k -= 2 ) * k * ( ( s + 1 ) * k + s ) + 2 );

              }

          },

          Bounce: {

              In: function ( k ) {

                  return 1 - TWEEN.Easing.Bounce.Out( 1 - k );

              },

              Out: function ( k ) {

                  if ( k < ( 1 / 2.75 ) ) {

                      return 7.5625 * k * k;

                  } else if ( k < ( 2 / 2.75 ) ) {

                      return 7.5625 * ( k -= ( 1.5 / 2.75 ) ) * k + 0.75;

                  } else if ( k < ( 2.5 / 2.75 ) ) {

                      return 7.5625 * ( k -= ( 2.25 / 2.75 ) ) * k + 0.9375;

                  } else {

                      return 7.5625 * ( k -= ( 2.625 / 2.75 ) ) * k + 0.984375;

                  }

              },

              InOut: function ( k ) {

                  if ( k < 0.5 ) return TWEEN.Easing.Bounce.In( k * 2 ) * 0.5;
                  return TWEEN.Easing.Bounce.Out( k * 2 - 1 ) * 0.5 + 0.5;

              }

          }

      };

      TWEEN.Interpolation = {

          Linear: function ( v, k ) {

              var m = v.length - 1, f = m * k, i = Math.floor( f ), fn = TWEEN.Interpolation.Utils.Linear;

              if ( k < 0 ) return fn( v[ 0 ], v[ 1 ], f );
              if ( k > 1 ) return fn( v[ m ], v[ m - 1 ], m - f );

              return fn( v[ i ], v[ i + 1 > m ? m : i + 1 ], f - i );

          },

          Bezier: function ( v, k ) {

              var b = 0, n = v.length - 1, pw = Math.pow, bn = TWEEN.Interpolation.Utils.Bernstein, i;

              for ( i = 0; i <= n; i++ ) {
                  b += pw( 1 - k, n - i ) * pw( k, i ) * v[ i ] * bn( n, i );
              }

              return b;

          },

          CatmullRom: function ( v, k ) {

              var m = v.length - 1, f = m * k, i = Math.floor( f ), fn = TWEEN.Interpolation.Utils.CatmullRom;

              if ( v[ 0 ] === v[ m ] ) {

                  if ( k < 0 ) i = Math.floor( f = m * ( 1 + k ) );

                  return fn( v[ ( i - 1 + m ) % m ], v[ i ], v[ ( i + 1 ) % m ], v[ ( i + 2 ) % m ], f - i );

              } else {

                  if ( k < 0 ) return v[ 0 ] - ( fn( v[ 0 ], v[ 0 ], v[ 1 ], v[ 1 ], -f ) - v[ 0 ] );
                  if ( k > 1 ) return v[ m ] - ( fn( v[ m ], v[ m ], v[ m - 1 ], v[ m - 1 ], f - m ) - v[ m ] );

                  return fn( v[ i ? i - 1 : 0 ], v[ i ], v[ m < i + 1 ? m : i + 1 ], v[ m < i + 2 ? m : i + 2 ], f - i );

              }

          },

          Utils: {

              Linear: function ( p0, p1, t ) {

                  return ( p1 - p0 ) * t + p0;

              },

              Bernstein: function ( n , i ) {

                  var fc = TWEEN.Interpolation.Utils.Factorial;
                  return fc( n ) / fc( i ) / fc( n - i );

              },

              Factorial: ( function () {

                  var a = [ 1 ];

                  return function ( n ) {

                      var s = 1, i;
                      if ( a[ n ] ) return a[ n ];
                      for ( i = n; i > 1; i-- ) s *= i;
                      return a[ n ] = s;

                  };

              } )(),

              CatmullRom: function ( p0, p1, p2, p3, t ) {

                  var v0 = ( p2 - p0 ) * 0.5, v1 = ( p3 - p1 ) * 0.5, t2 = t * t, t3 = t * t2;
                  return ( 2 * p1 - 2 * p2 + v0 + v1 ) * t3 + ( - 3 * p1 + 3 * p2 - 2 * v0 - v1 ) * t2 + v0 * t + p1;

              }

          }

      };

  /**
   * Easing functions for use with TweenCollection.  These function are from
   * {@link https://github.com/sole/tween.js/|Tween.js} and Robert Penner.  See the
   * {@link http://sole.github.io/tween.js/examples/03_graphs.html|Tween.js graphs for each function}.
   *
   * @namespace
   */
  var EasingFunction = {
    /**
     * Linear easing.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    LINEAR_NONE: TWEEN.Easing.Linear.None,

    /**
     * Quadratic in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUADRACTIC_IN: TWEEN.Easing.Quadratic.In,
    /**
     * Quadratic out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUADRACTIC_OUT: TWEEN.Easing.Quadratic.Out,
    /**
     * Quadratic in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUADRACTIC_IN_OUT: TWEEN.Easing.Quadratic.InOut,

    /**
     * Cubic in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    CUBIC_IN: TWEEN.Easing.Cubic.In,
    /**
     * Cubic out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    CUBIC_OUT: TWEEN.Easing.Cubic.Out,
    /**
     * Cubic in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    CUBIC_IN_OUT: TWEEN.Easing.Cubic.InOut,

    /**
     * Quartic in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUARTIC_IN: TWEEN.Easing.Quartic.In,
    /**
     * Quartic out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUARTIC_OUT: TWEEN.Easing.Quartic.Out,
    /**
     * Quartic in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUARTIC_IN_OUT: TWEEN.Easing.Quartic.InOut,

    /**
     * Quintic in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUINTIC_IN: TWEEN.Easing.Quintic.In,
    /**
     * Quintic out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUINTIC_OUT: TWEEN.Easing.Quintic.Out,
    /**
     * Quintic in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    QUINTIC_IN_OUT: TWEEN.Easing.Quintic.InOut,

    /**
     * Sinusoidal in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    SINUSOIDAL_IN: TWEEN.Easing.Sinusoidal.In,
    /**
     * Sinusoidal out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    SINUSOIDAL_OUT: TWEEN.Easing.Sinusoidal.Out,
    /**
     * Sinusoidal in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    SINUSOIDAL_IN_OUT: TWEEN.Easing.Sinusoidal.InOut,

    /**
     * Exponential in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    EXPONENTIAL_IN: TWEEN.Easing.Exponential.In,
    /**
     * Exponential out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    EXPONENTIAL_OUT: TWEEN.Easing.Exponential.Out,
    /**
     * Exponential in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    EXPONENTIAL_IN_OUT: TWEEN.Easing.Exponential.InOut,

    /**
     * Circular in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    CIRCULAR_IN: TWEEN.Easing.Circular.In,
    /**
     * Circular out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    CIRCULAR_OUT: TWEEN.Easing.Circular.Out,
    /**
     * Circular in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    CIRCULAR_IN_OUT: TWEEN.Easing.Circular.InOut,

    /**
     * Elastic in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    ELASTIC_IN: TWEEN.Easing.Elastic.In,
    /**
     * Elastic out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    ELASTIC_OUT: TWEEN.Easing.Elastic.Out,
    /**
     * Elastic in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    ELASTIC_IN_OUT: TWEEN.Easing.Elastic.InOut,

    /**
     * Back in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    BACK_IN: TWEEN.Easing.Back.In,
    /**
     * Back out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    BACK_OUT: TWEEN.Easing.Back.Out,
    /**
     * Back in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    BACK_IN_OUT: TWEEN.Easing.Back.InOut,

    /**
     * Bounce in.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    BOUNCE_IN: TWEEN.Easing.Bounce.In,
    /**
     * Bounce out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    BOUNCE_OUT: TWEEN.Easing.Bounce.Out,
    /**
     * Bounce in then out.
     *
     * @type {EasingFunction.Callback}
     * @constant
     */
    BOUNCE_IN_OUT: TWEEN.Easing.Bounce.InOut,
  };

  /**
   * Function interface for implementing a custom easing function.
   * @callback EasingFunction.Callback
   * @param {Number} time The time in the range <code>[0, 1]</code>.
   * @returns {Number} The value of the function at the given time.
   *
   * @example
   * function quadraticIn(time) {
   *     return time * time;
   * }
   *
   * @example
   * function quadraticOut(time) {
   *     return time * (2.0 - time);
   * }
   */
  var EasingFunction$1 = Object.freeze(EasingFunction);

  var scratchPosition$2 = new Cartesian3();
  var scratchNormal$4 = new Cartesian3();
  var scratchTangent$2 = new Cartesian3();
  var scratchBitangent$2 = new Cartesian3();
  var scratchNormalST = new Cartesian3();
  var defaultRadii = new Cartesian3(1.0, 1.0, 1.0);

  var cos = Math.cos;
  var sin = Math.sin;

  /**
   * A description of an ellipsoid centered at the origin.
   *
   * @alias EllipsoidGeometry
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Cartesian3} [options.radii=Cartesian3(1.0, 1.0, 1.0)] The radii of the ellipsoid in the x, y, and z directions.
   * @param {Cartesian3} [options.innerRadii=options.radii] The inner radii of the ellipsoid in the x, y, and z directions.
   * @param {Number} [options.minimumClock=0.0] The minimum angle lying in the xy-plane measured from the positive x-axis and toward the positive y-axis.
   * @param {Number} [options.maximumClock=2*PI] The maximum angle lying in the xy-plane measured from the positive x-axis and toward the positive y-axis.
   * @param {Number} [options.minimumCone=0.0] The minimum angle measured from the positive z-axis and toward the negative z-axis.
   * @param {Number} [options.maximumCone=PI] The maximum angle measured from the positive z-axis and toward the negative z-axis.
   * @param {Number} [options.stackPartitions=64] The number of times to partition the ellipsoid into stacks.
   * @param {Number} [options.slicePartitions=64] The number of times to partition the ellipsoid into radial slices.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @exception {DeveloperError} options.slicePartitions cannot be less than three.
   * @exception {DeveloperError} options.stackPartitions cannot be less than three.
   *
   * @see EllipsoidGeometry#createGeometry
   *
   * @example
   * var ellipsoid = new Cesium.EllipsoidGeometry({
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY,
   *   radii : new Cesium.Cartesian3(1000000.0, 500000.0, 500000.0)
   * });
   * var geometry = Cesium.EllipsoidGeometry.createGeometry(ellipsoid);
   */
  function EllipsoidGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var radii = defaultValue(options.radii, defaultRadii);
    var innerRadii = defaultValue(options.innerRadii, radii);
    var minimumClock = defaultValue(options.minimumClock, 0.0);
    var maximumClock = defaultValue(options.maximumClock, CesiumMath.TWO_PI);
    var minimumCone = defaultValue(options.minimumCone, 0.0);
    var maximumCone = defaultValue(options.maximumCone, CesiumMath.PI);
    var stackPartitions = Math.round(defaultValue(options.stackPartitions, 64));
    var slicePartitions = Math.round(defaultValue(options.slicePartitions, 64));
    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);

    //>>includeStart('debug', pragmas.debug);
    if (slicePartitions < 3) {
      throw new DeveloperError(
        "options.slicePartitions cannot be less than three."
      );
    }
    if (stackPartitions < 3) {
      throw new DeveloperError(
        "options.stackPartitions cannot be less than three."
      );
    }
    //>>includeEnd('debug');

    this._radii = Cartesian3.clone(radii);
    this._innerRadii = Cartesian3.clone(innerRadii);
    this._minimumClock = minimumClock;
    this._maximumClock = maximumClock;
    this._minimumCone = minimumCone;
    this._maximumCone = maximumCone;
    this._stackPartitions = stackPartitions;
    this._slicePartitions = slicePartitions;
    this._vertexFormat = VertexFormat.clone(vertexFormat);
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createEllipsoidGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  EllipsoidGeometry.packedLength =
    2 * Cartesian3.packedLength + VertexFormat.packedLength + 7;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {EllipsoidGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  EllipsoidGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._radii, array, startingIndex);
    startingIndex += Cartesian3.packedLength;

    Cartesian3.pack(value._innerRadii, array, startingIndex);
    startingIndex += Cartesian3.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._minimumClock;
    array[startingIndex++] = value._maximumClock;
    array[startingIndex++] = value._minimumCone;
    array[startingIndex++] = value._maximumCone;
    array[startingIndex++] = value._stackPartitions;
    array[startingIndex++] = value._slicePartitions;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchRadii = new Cartesian3();
  var scratchInnerRadii = new Cartesian3();
  var scratchVertexFormat$5 = new VertexFormat();
  var scratchOptions$c = {
    radii: scratchRadii,
    innerRadii: scratchInnerRadii,
    vertexFormat: scratchVertexFormat$5,
    minimumClock: undefined,
    maximumClock: undefined,
    minimumCone: undefined,
    maximumCone: undefined,
    stackPartitions: undefined,
    slicePartitions: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {EllipsoidGeometry} [result] The object into which to store the result.
   * @returns {EllipsoidGeometry} The modified result parameter or a new EllipsoidGeometry instance if one was not provided.
   */
  EllipsoidGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var radii = Cartesian3.unpack(array, startingIndex, scratchRadii);
    startingIndex += Cartesian3.packedLength;

    var innerRadii = Cartesian3.unpack(array, startingIndex, scratchInnerRadii);
    startingIndex += Cartesian3.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$5
    );
    startingIndex += VertexFormat.packedLength;

    var minimumClock = array[startingIndex++];
    var maximumClock = array[startingIndex++];
    var minimumCone = array[startingIndex++];
    var maximumCone = array[startingIndex++];
    var stackPartitions = array[startingIndex++];
    var slicePartitions = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$c.minimumClock = minimumClock;
      scratchOptions$c.maximumClock = maximumClock;
      scratchOptions$c.minimumCone = minimumCone;
      scratchOptions$c.maximumCone = maximumCone;
      scratchOptions$c.stackPartitions = stackPartitions;
      scratchOptions$c.slicePartitions = slicePartitions;
      scratchOptions$c.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new EllipsoidGeometry(scratchOptions$c);
    }

    result._radii = Cartesian3.clone(radii, result._radii);
    result._innerRadii = Cartesian3.clone(innerRadii, result._innerRadii);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._minimumClock = minimumClock;
    result._maximumClock = maximumClock;
    result._minimumCone = minimumCone;
    result._maximumCone = maximumCone;
    result._stackPartitions = stackPartitions;
    result._slicePartitions = slicePartitions;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of an ellipsoid, including its vertices, indices, and a bounding sphere.
   *
   * @param {EllipsoidGeometry} ellipsoidGeometry A description of the ellipsoid.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  EllipsoidGeometry.createGeometry = function (ellipsoidGeometry) {
    var radii = ellipsoidGeometry._radii;
    if (radii.x <= 0 || radii.y <= 0 || radii.z <= 0) {
      return;
    }

    var innerRadii = ellipsoidGeometry._innerRadii;
    if (innerRadii.x <= 0 || innerRadii.y <= 0 || innerRadii.z <= 0) {
      return;
    }

    var minimumClock = ellipsoidGeometry._minimumClock;
    var maximumClock = ellipsoidGeometry._maximumClock;
    var minimumCone = ellipsoidGeometry._minimumCone;
    var maximumCone = ellipsoidGeometry._maximumCone;
    var vertexFormat = ellipsoidGeometry._vertexFormat;

    // Add an extra slice and stack so that the number of partitions is the
    // number of surfaces rather than the number of joints
    var slicePartitions = ellipsoidGeometry._slicePartitions + 1;
    var stackPartitions = ellipsoidGeometry._stackPartitions + 1;

    slicePartitions = Math.round(
      (slicePartitions * Math.abs(maximumClock - minimumClock)) /
        CesiumMath.TWO_PI
    );
    stackPartitions = Math.round(
      (stackPartitions * Math.abs(maximumCone - minimumCone)) / CesiumMath.PI
    );

    if (slicePartitions < 2) {
      slicePartitions = 2;
    }
    if (stackPartitions < 2) {
      stackPartitions = 2;
    }

    var i;
    var j;
    var index = 0;

    // Create arrays for theta and phi. Duplicate first and last angle to
    // allow different normals at the intersections.
    var phis = [minimumCone];
    var thetas = [minimumClock];
    for (i = 0; i < stackPartitions; i++) {
      phis.push(
        minimumCone + (i * (maximumCone - minimumCone)) / (stackPartitions - 1)
      );
    }
    phis.push(maximumCone);
    for (j = 0; j < slicePartitions; j++) {
      thetas.push(
        minimumClock + (j * (maximumClock - minimumClock)) / (slicePartitions - 1)
      );
    }
    thetas.push(maximumClock);
    var numPhis = phis.length;
    var numThetas = thetas.length;

    // Allow for extra indices if there is an inner surface and if we need
    // to close the sides if the clock range is not a full circle
    var extraIndices = 0;
    var vertexMultiplier = 1.0;
    var hasInnerSurface =
      innerRadii.x !== radii.x ||
      innerRadii.y !== radii.y ||
      innerRadii.z !== radii.z;
    var isTopOpen = false;
    var isBotOpen = false;
    var isClockOpen = false;
    if (hasInnerSurface) {
      vertexMultiplier = 2.0;
      if (minimumCone > 0.0) {
        isTopOpen = true;
        extraIndices += slicePartitions - 1;
      }
      if (maximumCone < Math.PI) {
        isBotOpen = true;
        extraIndices += slicePartitions - 1;
      }
      if ((maximumClock - minimumClock) % CesiumMath.TWO_PI) {
        isClockOpen = true;
        extraIndices += (stackPartitions - 1) * 2 + 1;
      } else {
        extraIndices += 1;
      }
    }

    var vertexCount = numThetas * numPhis * vertexMultiplier;
    var positions = new Float64Array(vertexCount * 3);
    var isInner = arrayFill(new Array(vertexCount), false);
    var negateNormal = arrayFill(new Array(vertexCount), false);

    // Multiply by 6 because there are two triangles per sector
    var indexCount = slicePartitions * stackPartitions * vertexMultiplier;
    var numIndices =
      6 *
      (indexCount +
        extraIndices +
        1 -
        (slicePartitions + stackPartitions) * vertexMultiplier);
    var indices = IndexDatatype$1.createTypedArray(indexCount, numIndices);

    var normals = vertexFormat.normal
      ? new Float32Array(vertexCount * 3)
      : undefined;
    var tangents = vertexFormat.tangent
      ? new Float32Array(vertexCount * 3)
      : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(vertexCount * 3)
      : undefined;
    var st = vertexFormat.st ? new Float32Array(vertexCount * 2) : undefined;

    // Calculate sin/cos phi
    var sinPhi = new Array(numPhis);
    var cosPhi = new Array(numPhis);
    for (i = 0; i < numPhis; i++) {
      sinPhi[i] = sin(phis[i]);
      cosPhi[i] = cos(phis[i]);
    }

    // Calculate sin/cos theta
    var sinTheta = new Array(numThetas);
    var cosTheta = new Array(numThetas);
    for (j = 0; j < numThetas; j++) {
      cosTheta[j] = cos(thetas[j]);
      sinTheta[j] = sin(thetas[j]);
    }

    // Create outer surface
    for (i = 0; i < numPhis; i++) {
      for (j = 0; j < numThetas; j++) {
        positions[index++] = radii.x * sinPhi[i] * cosTheta[j];
        positions[index++] = radii.y * sinPhi[i] * sinTheta[j];
        positions[index++] = radii.z * cosPhi[i];
      }
    }

    // Create inner surface
    var vertexIndex = vertexCount / 2.0;
    if (hasInnerSurface) {
      for (i = 0; i < numPhis; i++) {
        for (j = 0; j < numThetas; j++) {
          positions[index++] = innerRadii.x * sinPhi[i] * cosTheta[j];
          positions[index++] = innerRadii.y * sinPhi[i] * sinTheta[j];
          positions[index++] = innerRadii.z * cosPhi[i];

          // Keep track of which vertices are the inner and which ones
          // need the normal to be negated
          isInner[vertexIndex] = true;
          if (i > 0 && i !== numPhis - 1 && j !== 0 && j !== numThetas - 1) {
            negateNormal[vertexIndex] = true;
          }
          vertexIndex++;
        }
      }
    }

    // Create indices for outer surface
    index = 0;
    var topOffset;
    var bottomOffset;
    for (i = 1; i < numPhis - 2; i++) {
      topOffset = i * numThetas;
      bottomOffset = (i + 1) * numThetas;

      for (j = 1; j < numThetas - 2; j++) {
        indices[index++] = bottomOffset + j;
        indices[index++] = bottomOffset + j + 1;
        indices[index++] = topOffset + j + 1;

        indices[index++] = bottomOffset + j;
        indices[index++] = topOffset + j + 1;
        indices[index++] = topOffset + j;
      }
    }

    // Create indices for inner surface
    if (hasInnerSurface) {
      var offset = numPhis * numThetas;
      for (i = 1; i < numPhis - 2; i++) {
        topOffset = offset + i * numThetas;
        bottomOffset = offset + (i + 1) * numThetas;

        for (j = 1; j < numThetas - 2; j++) {
          indices[index++] = bottomOffset + j;
          indices[index++] = topOffset + j;
          indices[index++] = topOffset + j + 1;

          indices[index++] = bottomOffset + j;
          indices[index++] = topOffset + j + 1;
          indices[index++] = bottomOffset + j + 1;
        }
      }
    }

    var outerOffset;
    var innerOffset;
    if (hasInnerSurface) {
      if (isTopOpen) {
        // Connect the top of the inner surface to the top of the outer surface
        innerOffset = numPhis * numThetas;
        for (i = 1; i < numThetas - 2; i++) {
          indices[index++] = i;
          indices[index++] = i + 1;
          indices[index++] = innerOffset + i + 1;

          indices[index++] = i;
          indices[index++] = innerOffset + i + 1;
          indices[index++] = innerOffset + i;
        }
      }

      if (isBotOpen) {
        // Connect the bottom of the inner surface to the bottom of the outer surface
        outerOffset = numPhis * numThetas - numThetas;
        innerOffset = numPhis * numThetas * vertexMultiplier - numThetas;
        for (i = 1; i < numThetas - 2; i++) {
          indices[index++] = outerOffset + i + 1;
          indices[index++] = outerOffset + i;
          indices[index++] = innerOffset + i;

          indices[index++] = outerOffset + i + 1;
          indices[index++] = innerOffset + i;
          indices[index++] = innerOffset + i + 1;
        }
      }
    }

    // Connect the edges if clock is not closed
    if (isClockOpen) {
      for (i = 1; i < numPhis - 2; i++) {
        innerOffset = numThetas * numPhis + numThetas * i;
        outerOffset = numThetas * i;
        indices[index++] = innerOffset;
        indices[index++] = outerOffset + numThetas;
        indices[index++] = outerOffset;

        indices[index++] = innerOffset;
        indices[index++] = innerOffset + numThetas;
        indices[index++] = outerOffset + numThetas;
      }

      for (i = 1; i < numPhis - 2; i++) {
        innerOffset = numThetas * numPhis + numThetas * (i + 1) - 1;
        outerOffset = numThetas * (i + 1) - 1;
        indices[index++] = outerOffset + numThetas;
        indices[index++] = innerOffset;
        indices[index++] = outerOffset;

        indices[index++] = outerOffset + numThetas;
        indices[index++] = innerOffset + numThetas;
        indices[index++] = innerOffset;
      }
    }

    var attributes = new GeometryAttributes();

    if (vertexFormat.position) {
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      });
    }

    var stIndex = 0;
    var normalIndex = 0;
    var tangentIndex = 0;
    var bitangentIndex = 0;
    var vertexCountHalf = vertexCount / 2.0;

    var ellipsoid;
    var ellipsoidOuter = Ellipsoid.fromCartesian3(radii);
    var ellipsoidInner = Ellipsoid.fromCartesian3(innerRadii);

    if (
      vertexFormat.st ||
      vertexFormat.normal ||
      vertexFormat.tangent ||
      vertexFormat.bitangent
    ) {
      for (i = 0; i < vertexCount; i++) {
        ellipsoid = isInner[i] ? ellipsoidInner : ellipsoidOuter;
        var position = Cartesian3.fromArray(positions, i * 3, scratchPosition$2);
        var normal = ellipsoid.geodeticSurfaceNormal(position, scratchNormal$4);
        if (negateNormal[i]) {
          Cartesian3.negate(normal, normal);
        }

        if (vertexFormat.st) {
          var normalST = Cartesian2.negate(normal, scratchNormalST);
          st[stIndex++] =
            Math.atan2(normalST.y, normalST.x) / CesiumMath.TWO_PI + 0.5;
          st[stIndex++] = Math.asin(normal.z) / Math.PI + 0.5;
        }

        if (vertexFormat.normal) {
          normals[normalIndex++] = normal.x;
          normals[normalIndex++] = normal.y;
          normals[normalIndex++] = normal.z;
        }

        if (vertexFormat.tangent || vertexFormat.bitangent) {
          var tangent = scratchTangent$2;

          // Use UNIT_X for the poles
          var tangetOffset = 0;
          var unit;
          if (isInner[i]) {
            tangetOffset = vertexCountHalf;
          }
          if (
            !isTopOpen &&
            i >= tangetOffset &&
            i < tangetOffset + numThetas * 2
          ) {
            unit = Cartesian3.UNIT_X;
          } else {
            unit = Cartesian3.UNIT_Z;
          }
          Cartesian3.cross(unit, normal, tangent);
          Cartesian3.normalize(tangent, tangent);

          if (vertexFormat.tangent) {
            tangents[tangentIndex++] = tangent.x;
            tangents[tangentIndex++] = tangent.y;
            tangents[tangentIndex++] = tangent.z;
          }

          if (vertexFormat.bitangent) {
            var bitangent = Cartesian3.cross(normal, tangent, scratchBitangent$2);
            Cartesian3.normalize(bitangent, bitangent);

            bitangents[bitangentIndex++] = bitangent.x;
            bitangents[bitangentIndex++] = bitangent.y;
            bitangents[bitangentIndex++] = bitangent.z;
          }
        }
      }

      if (vertexFormat.st) {
        attributes.st = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 2,
          values: st,
        });
      }

      if (vertexFormat.normal) {
        attributes.normal = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: normals,
        });
      }

      if (vertexFormat.tangent) {
        attributes.tangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: tangents,
        });
      }

      if (vertexFormat.bitangent) {
        attributes.bitangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: bitangents,
        });
      }
    }

    if (defined(ellipsoidGeometry._offsetAttribute)) {
      var length = positions.length;
      var applyOffset = new Uint8Array(length / 3);
      var offsetValue =
        ellipsoidGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
          ? 0
          : 1;
      arrayFill(applyOffset, offsetValue);
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: BoundingSphere.fromEllipsoid(ellipsoidOuter),
      offsetAttribute: ellipsoidGeometry._offsetAttribute,
    });
  };

  var unitEllipsoidGeometry;

  /**
   * Returns the geometric representation of a unit ellipsoid, including its vertices, indices, and a bounding sphere.
   * @returns {Geometry} The computed vertices and indices.
   *
   * @private
   */
  EllipsoidGeometry.getUnitEllipsoid = function () {
    if (!defined(unitEllipsoidGeometry)) {
      unitEllipsoidGeometry = EllipsoidGeometry.createGeometry(
        new EllipsoidGeometry({
          radii: new Cartesian3(1.0, 1.0, 1.0),
          vertexFormat: VertexFormat.POSITION_ONLY,
        })
      );
    }
    return unitEllipsoidGeometry;
  };

  var defaultRadii$1 = new Cartesian3(1.0, 1.0, 1.0);
  var cos$1 = Math.cos;
  var sin$1 = Math.sin;

  /**
   * A description of the outline of an ellipsoid centered at the origin.
   *
   * @alias EllipsoidOutlineGeometry
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Cartesian3} [options.radii=Cartesian3(1.0, 1.0, 1.0)] The radii of the ellipsoid in the x, y, and z directions.
   * @param {Cartesian3} [options.innerRadii=options.radii] The inner radii of the ellipsoid in the x, y, and z directions.
   * @param {Number} [options.minimumClock=0.0] The minimum angle lying in the xy-plane measured from the positive x-axis and toward the positive y-axis.
   * @param {Number} [options.maximumClock=2*PI] The maximum angle lying in the xy-plane measured from the positive x-axis and toward the positive y-axis.
   * @param {Number} [options.minimumCone=0.0] The minimum angle measured from the positive z-axis and toward the negative z-axis.
   * @param {Number} [options.maximumCone=PI] The maximum angle measured from the positive z-axis and toward the negative z-axis.
   * @param {Number} [options.stackPartitions=10] The count of stacks for the ellipsoid (1 greater than the number of parallel lines).
   * @param {Number} [options.slicePartitions=8] The count of slices for the ellipsoid (Equal to the number of radial lines).
   * @param {Number} [options.subdivisions=128] The number of points per line, determining the granularity of the curvature.
   *
   * @exception {DeveloperError} options.stackPartitions must be greater than or equal to one.
   * @exception {DeveloperError} options.slicePartitions must be greater than or equal to zero.
   * @exception {DeveloperError} options.subdivisions must be greater than or equal to zero.
   *
   * @example
   * var ellipsoid = new Cesium.EllipsoidOutlineGeometry({
   *   radii : new Cesium.Cartesian3(1000000.0, 500000.0, 500000.0),
   *   stackPartitions: 6,
   *   slicePartitions: 5
   * });
   * var geometry = Cesium.EllipsoidOutlineGeometry.createGeometry(ellipsoid);
   */
  function EllipsoidOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var radii = defaultValue(options.radii, defaultRadii$1);
    var innerRadii = defaultValue(options.innerRadii, radii);
    var minimumClock = defaultValue(options.minimumClock, 0.0);
    var maximumClock = defaultValue(options.maximumClock, CesiumMath.TWO_PI);
    var minimumCone = defaultValue(options.minimumCone, 0.0);
    var maximumCone = defaultValue(options.maximumCone, CesiumMath.PI);
    var stackPartitions = Math.round(defaultValue(options.stackPartitions, 10));
    var slicePartitions = Math.round(defaultValue(options.slicePartitions, 8));
    var subdivisions = Math.round(defaultValue(options.subdivisions, 128));

    //>>includeStart('debug', pragmas.debug);
    if (stackPartitions < 1) {
      throw new DeveloperError("options.stackPartitions cannot be less than 1");
    }
    if (slicePartitions < 0) {
      throw new DeveloperError("options.slicePartitions cannot be less than 0");
    }
    if (subdivisions < 0) {
      throw new DeveloperError(
        "options.subdivisions must be greater than or equal to zero."
      );
    }
    if (
      defined(options.offsetAttribute) &&
      options.offsetAttribute === GeometryOffsetAttribute$1.TOP
    ) {
      throw new DeveloperError(
        "GeometryOffsetAttribute.TOP is not a supported options.offsetAttribute for this geometry."
      );
    }
    //>>includeEnd('debug');

    this._radii = Cartesian3.clone(radii);
    this._innerRadii = Cartesian3.clone(innerRadii);
    this._minimumClock = minimumClock;
    this._maximumClock = maximumClock;
    this._minimumCone = minimumCone;
    this._maximumCone = maximumCone;
    this._stackPartitions = stackPartitions;
    this._slicePartitions = slicePartitions;
    this._subdivisions = subdivisions;
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createEllipsoidOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  EllipsoidOutlineGeometry.packedLength = 2 * Cartesian3.packedLength + 8;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {EllipsoidOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  EllipsoidOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Cartesian3.pack(value._radii, array, startingIndex);
    startingIndex += Cartesian3.packedLength;

    Cartesian3.pack(value._innerRadii, array, startingIndex);
    startingIndex += Cartesian3.packedLength;

    array[startingIndex++] = value._minimumClock;
    array[startingIndex++] = value._maximumClock;
    array[startingIndex++] = value._minimumCone;
    array[startingIndex++] = value._maximumCone;
    array[startingIndex++] = value._stackPartitions;
    array[startingIndex++] = value._slicePartitions;
    array[startingIndex++] = value._subdivisions;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchRadii$1 = new Cartesian3();
  var scratchInnerRadii$1 = new Cartesian3();
  var scratchOptions$d = {
    radii: scratchRadii$1,
    innerRadii: scratchInnerRadii$1,
    minimumClock: undefined,
    maximumClock: undefined,
    minimumCone: undefined,
    maximumCone: undefined,
    stackPartitions: undefined,
    slicePartitions: undefined,
    subdivisions: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {EllipsoidOutlineGeometry} [result] The object into which to store the result.
   * @returns {EllipsoidOutlineGeometry} The modified result parameter or a new EllipsoidOutlineGeometry instance if one was not provided.
   */
  EllipsoidOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var radii = Cartesian3.unpack(array, startingIndex, scratchRadii$1);
    startingIndex += Cartesian3.packedLength;

    var innerRadii = Cartesian3.unpack(array, startingIndex, scratchInnerRadii$1);
    startingIndex += Cartesian3.packedLength;

    var minimumClock = array[startingIndex++];
    var maximumClock = array[startingIndex++];
    var minimumCone = array[startingIndex++];
    var maximumCone = array[startingIndex++];
    var stackPartitions = array[startingIndex++];
    var slicePartitions = array[startingIndex++];
    var subdivisions = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$d.minimumClock = minimumClock;
      scratchOptions$d.maximumClock = maximumClock;
      scratchOptions$d.minimumCone = minimumCone;
      scratchOptions$d.maximumCone = maximumCone;
      scratchOptions$d.stackPartitions = stackPartitions;
      scratchOptions$d.slicePartitions = slicePartitions;
      scratchOptions$d.subdivisions = subdivisions;
      scratchOptions$d.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;
      return new EllipsoidOutlineGeometry(scratchOptions$d);
    }

    result._radii = Cartesian3.clone(radii, result._radii);
    result._innerRadii = Cartesian3.clone(innerRadii, result._innerRadii);
    result._minimumClock = minimumClock;
    result._maximumClock = maximumClock;
    result._minimumCone = minimumCone;
    result._maximumCone = maximumCone;
    result._stackPartitions = stackPartitions;
    result._slicePartitions = slicePartitions;
    result._subdivisions = subdivisions;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the geometric representation of an outline of an ellipsoid, including its vertices, indices, and a bounding sphere.
   *
   * @param {EllipsoidOutlineGeometry} ellipsoidGeometry A description of the ellipsoid outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  EllipsoidOutlineGeometry.createGeometry = function (ellipsoidGeometry) {
    var radii = ellipsoidGeometry._radii;
    if (radii.x <= 0 || radii.y <= 0 || radii.z <= 0) {
      return;
    }

    var innerRadii = ellipsoidGeometry._innerRadii;
    if (innerRadii.x <= 0 || innerRadii.y <= 0 || innerRadii.z <= 0) {
      return;
    }

    var minimumClock = ellipsoidGeometry._minimumClock;
    var maximumClock = ellipsoidGeometry._maximumClock;
    var minimumCone = ellipsoidGeometry._minimumCone;
    var maximumCone = ellipsoidGeometry._maximumCone;
    var subdivisions = ellipsoidGeometry._subdivisions;
    var ellipsoid = Ellipsoid.fromCartesian3(radii);

    // Add an extra slice and stack to remain consistent with EllipsoidGeometry
    var slicePartitions = ellipsoidGeometry._slicePartitions + 1;
    var stackPartitions = ellipsoidGeometry._stackPartitions + 1;

    slicePartitions = Math.round(
      (slicePartitions * Math.abs(maximumClock - minimumClock)) /
        CesiumMath.TWO_PI
    );
    stackPartitions = Math.round(
      (stackPartitions * Math.abs(maximumCone - minimumCone)) / CesiumMath.PI
    );

    if (slicePartitions < 2) {
      slicePartitions = 2;
    }
    if (stackPartitions < 2) {
      stackPartitions = 2;
    }

    var extraIndices = 0;
    var vertexMultiplier = 1.0;
    var hasInnerSurface =
      innerRadii.x !== radii.x ||
      innerRadii.y !== radii.y ||
      innerRadii.z !== radii.z;
    var isTopOpen = false;
    var isBotOpen = false;
    if (hasInnerSurface) {
      vertexMultiplier = 2.0;
      // Add 2x slicePartitions to connect the top/bottom of the outer to
      // the top/bottom of the inner
      if (minimumCone > 0.0) {
        isTopOpen = true;
        extraIndices += slicePartitions;
      }
      if (maximumCone < Math.PI) {
        isBotOpen = true;
        extraIndices += slicePartitions;
      }
    }

    var vertexCount =
      subdivisions * vertexMultiplier * (stackPartitions + slicePartitions);
    var positions = new Float64Array(vertexCount * 3);

    // Multiply by two because two points define each line segment
    var numIndices =
      2 *
      (vertexCount +
        extraIndices -
        (slicePartitions + stackPartitions) * vertexMultiplier);
    var indices = IndexDatatype$1.createTypedArray(vertexCount, numIndices);

    var i;
    var j;
    var theta;
    var phi;
    var index = 0;

    // Calculate sin/cos phi
    var sinPhi = new Array(stackPartitions);
    var cosPhi = new Array(stackPartitions);
    for (i = 0; i < stackPartitions; i++) {
      phi =
        minimumCone + (i * (maximumCone - minimumCone)) / (stackPartitions - 1);
      sinPhi[i] = sin$1(phi);
      cosPhi[i] = cos$1(phi);
    }

    // Calculate sin/cos theta
    var sinTheta = new Array(subdivisions);
    var cosTheta = new Array(subdivisions);
    for (i = 0; i < subdivisions; i++) {
      theta =
        minimumClock + (i * (maximumClock - minimumClock)) / (subdivisions - 1);
      sinTheta[i] = sin$1(theta);
      cosTheta[i] = cos$1(theta);
    }

    // Calculate the latitude lines on the outer surface
    for (i = 0; i < stackPartitions; i++) {
      for (j = 0; j < subdivisions; j++) {
        positions[index++] = radii.x * sinPhi[i] * cosTheta[j];
        positions[index++] = radii.y * sinPhi[i] * sinTheta[j];
        positions[index++] = radii.z * cosPhi[i];
      }
    }

    // Calculate the latitude lines on the inner surface
    if (hasInnerSurface) {
      for (i = 0; i < stackPartitions; i++) {
        for (j = 0; j < subdivisions; j++) {
          positions[index++] = innerRadii.x * sinPhi[i] * cosTheta[j];
          positions[index++] = innerRadii.y * sinPhi[i] * sinTheta[j];
          positions[index++] = innerRadii.z * cosPhi[i];
        }
      }
    }

    // Calculate sin/cos phi
    sinPhi.length = subdivisions;
    cosPhi.length = subdivisions;
    for (i = 0; i < subdivisions; i++) {
      phi = minimumCone + (i * (maximumCone - minimumCone)) / (subdivisions - 1);
      sinPhi[i] = sin$1(phi);
      cosPhi[i] = cos$1(phi);
    }

    // Calculate sin/cos theta for each slice partition
    sinTheta.length = slicePartitions;
    cosTheta.length = slicePartitions;
    for (i = 0; i < slicePartitions; i++) {
      theta =
        minimumClock +
        (i * (maximumClock - minimumClock)) / (slicePartitions - 1);
      sinTheta[i] = sin$1(theta);
      cosTheta[i] = cos$1(theta);
    }

    // Calculate the longitude lines on the outer surface
    for (i = 0; i < subdivisions; i++) {
      for (j = 0; j < slicePartitions; j++) {
        positions[index++] = radii.x * sinPhi[i] * cosTheta[j];
        positions[index++] = radii.y * sinPhi[i] * sinTheta[j];
        positions[index++] = radii.z * cosPhi[i];
      }
    }

    // Calculate the longitude lines on the inner surface
    if (hasInnerSurface) {
      for (i = 0; i < subdivisions; i++) {
        for (j = 0; j < slicePartitions; j++) {
          positions[index++] = innerRadii.x * sinPhi[i] * cosTheta[j];
          positions[index++] = innerRadii.y * sinPhi[i] * sinTheta[j];
          positions[index++] = innerRadii.z * cosPhi[i];
        }
      }
    }

    // Create indices for the latitude lines
    index = 0;
    for (i = 0; i < stackPartitions * vertexMultiplier; i++) {
      var topOffset = i * subdivisions;
      for (j = 0; j < subdivisions - 1; j++) {
        indices[index++] = topOffset + j;
        indices[index++] = topOffset + j + 1;
      }
    }

    // Create indices for the outer longitude lines
    var offset = stackPartitions * subdivisions * vertexMultiplier;
    for (i = 0; i < slicePartitions; i++) {
      for (j = 0; j < subdivisions - 1; j++) {
        indices[index++] = offset + i + j * slicePartitions;
        indices[index++] = offset + i + (j + 1) * slicePartitions;
      }
    }

    // Create indices for the inner longitude lines
    if (hasInnerSurface) {
      offset =
        stackPartitions * subdivisions * vertexMultiplier +
        slicePartitions * subdivisions;
      for (i = 0; i < slicePartitions; i++) {
        for (j = 0; j < subdivisions - 1; j++) {
          indices[index++] = offset + i + j * slicePartitions;
          indices[index++] = offset + i + (j + 1) * slicePartitions;
        }
      }
    }

    if (hasInnerSurface) {
      var outerOffset = stackPartitions * subdivisions * vertexMultiplier;
      var innerOffset = outerOffset + subdivisions * slicePartitions;
      if (isTopOpen) {
        // Draw lines from the top of the inner surface to the top of the outer surface
        for (i = 0; i < slicePartitions; i++) {
          indices[index++] = outerOffset + i;
          indices[index++] = innerOffset + i;
        }
      }

      if (isBotOpen) {
        // Draw lines from the top of the inner surface to the top of the outer surface
        outerOffset += subdivisions * slicePartitions - slicePartitions;
        innerOffset += subdivisions * slicePartitions - slicePartitions;
        for (i = 0; i < slicePartitions; i++) {
          indices[index++] = outerOffset + i;
          indices[index++] = innerOffset + i;
        }
      }
    }

    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      }),
    });

    if (defined(ellipsoidGeometry._offsetAttribute)) {
      var length = positions.length;
      var applyOffset = new Uint8Array(length / 3);
      var offsetValue =
        ellipsoidGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
          ? 0
          : 1;
      arrayFill(applyOffset, offsetValue);
      attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: applyOffset,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: BoundingSphere.fromEllipsoid(ellipsoid),
      offsetAttribute: ellipsoidGeometry._offsetAttribute,
    });
  };

  /**
   * A very simple {@link TerrainProvider} that produces geometry by tessellating an ellipsoidal
   * surface.
   *
   * @alias EllipsoidTerrainProvider
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {TilingScheme} [options.tilingScheme] The tiling scheme specifying how the ellipsoidal
   * surface is broken into tiles.  If this parameter is not provided, a {@link GeographicTilingScheme}
   * is used.
   * @param {Ellipsoid} [options.ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   * this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   * parameter is specified, the WGS84 ellipsoid is used.
   *
   * @see TerrainProvider
   */
  function EllipsoidTerrainProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._tilingScheme = options.tilingScheme;
    if (!defined(this._tilingScheme)) {
      this._tilingScheme = new GeographicTilingScheme({
        ellipsoid: defaultValue(options.ellipsoid, Ellipsoid.WGS84),
      });
    }

    // Note: the 64 below does NOT need to match the actual vertex dimensions, because
    // the ellipsoid is significantly smoother than actual terrain.
    this._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
      this._tilingScheme.ellipsoid,
      64,
      this._tilingScheme.getNumberOfXTilesAtLevel(0)
    );

    this._errorEvent = new Event();
    this._readyPromise = when.resolve(true);
  }

  Object.defineProperties(EllipsoidTerrainProvider.prototype, {
    /**
     * Gets an event that is raised when the terrain provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets the credit to display when this terrain provider is active.  Typically this is used to credit
     * the source of the terrain.  This function should not be called before {@link EllipsoidTerrainProvider#ready} returns true.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link EllipsoidTerrainProvider#ready} returns true.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {GeographicTilingScheme}
     */
    tilingScheme: {
      get: function () {
        return this._tilingScheme;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: function () {
        return true;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets a value indicating whether or not the provider includes a water mask.  The water mask
     * indicates which areas of the globe are water rather than land, so they can be rendered
     * as a reflective surface with animated waves.  This function should not be
     * called before {@link EllipsoidTerrainProvider#ready} returns true.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {Boolean}
     */
    hasWaterMask: {
      get: function () {
        return false;
      },
    },

    /**
     * Gets a value indicating whether or not the requested tiles include vertex normals.
     * This function should not be called before {@link EllipsoidTerrainProvider#ready} returns true.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {Boolean}
     */
    hasVertexNormals: {
      get: function () {
        return false;
      },
    },
    /**
     * Gets an object that can be used to determine availability of terrain from this provider, such as
     * at points and in rectangles.  This function should not be called before
     * {@link TerrainProvider#ready} returns true.  This property may be undefined if availability
     * information is not available.
     * @memberof EllipsoidTerrainProvider.prototype
     * @type {TileAvailability}
     */
    availability: {
      get: function () {
        return undefined;
      },
    },
  });

  /**
   * Requests the geometry for a given tile.  This function should not be called before
   * {@link TerrainProvider#ready} returns true.  The result includes terrain
   * data and indicates that all child tiles are available.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @param {Request} [request] The request object. Intended for internal use only.
   *
   * @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry.  If this method
   *          returns undefined instead of a promise, it is an indication that too many requests are already
   *          pending and the request will be retried later.
   */
  EllipsoidTerrainProvider.prototype.requestTileGeometry = function (
    x,
    y,
    level,
    request
  ) {
    var width = 16;
    var height = 16;
    return when.resolve(
      new HeightmapTerrainData({
        buffer: new Uint8Array(width * height),
        width: width,
        height: height,
      })
    );
  };

  /**
   * Gets the maximum geometric error allowed in a tile at a given level.
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error.
   */
  EllipsoidTerrainProvider.prototype.getLevelMaximumGeometricError = function (
    level
  ) {
    return this._levelZeroMaximumGeometricError / (1 << level);
  };

  /**
   * Determines whether data for a tile is available to be loaded.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {Boolean} Undefined if not supported, otherwise true or false.
   */
  EllipsoidTerrainProvider.prototype.getTileDataAvailable = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Makes sure we load availability data for a tile
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {undefined|Promise<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
   */
  EllipsoidTerrainProvider.prototype.loadTileDataAvailability = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * A convenience object that simplifies the common pattern of attaching event listeners
   * to several events, then removing all those listeners at once later, for example, in
   * a destroy method.
   *
   * @alias EventHelper
   * @constructor
   *
   *
   * @example
   * var helper = new Cesium.EventHelper();
   *
   * helper.add(someObject.event, listener1, this);
   * helper.add(otherObject.event, listener2, this);
   *
   * // later...
   * helper.removeAll();
   *
   * @see Event
   */
  function EventHelper() {
    this._removalFunctions = [];
  }

  /**
   * Adds a listener to an event, and records the registration to be cleaned up later.
   *
   * @param {Event} event The event to attach to.
   * @param {Function} listener The function to be executed when the event is raised.
   * @param {Object} [scope] An optional object scope to serve as the <code>this</code>
   *        pointer in which the listener function will execute.
   * @returns {EventHelper.RemoveCallback} A function that will remove this event listener when invoked.
   *
   * @see Event#addEventListener
   */
  EventHelper.prototype.add = function (event, listener, scope) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(event)) {
      throw new DeveloperError("event is required");
    }
    //>>includeEnd('debug');

    var removalFunction = event.addEventListener(listener, scope);
    this._removalFunctions.push(removalFunction);

    var that = this;
    return function () {
      removalFunction();
      var removalFunctions = that._removalFunctions;
      removalFunctions.splice(removalFunctions.indexOf(removalFunction), 1);
    };
  };

  /**
   * Unregisters all previously added listeners.
   *
   * @see Event#removeEventListener
   */
  EventHelper.prototype.removeAll = function () {
    var removalFunctions = this._removalFunctions;
    for (var i = 0, len = removalFunctions.length; i < len; ++i) {
      removalFunctions[i]();
    }
    removalFunctions.length = 0;
  };

  /**
   * Constants to determine how an interpolated value is extrapolated
   * when querying outside the bounds of available data.
   *
   * @enum {Number}
   *
   * @see SampledProperty
   */
  var ExtrapolationType = {
    /**
     * No extrapolation occurs.
     *
     * @type {Number}
     * @constant
     */
    NONE: 0,

    /**
     * The first or last value is used when outside the range of sample data.
     *
     * @type {Number}
     * @constant
     */
    HOLD: 1,

    /**
     * The value is extrapolated.
     *
     * @type {Number}
     * @constant
     */
    EXTRAPOLATE: 2,
  };
  var ExtrapolationType$1 = Object.freeze(ExtrapolationType);

  /**
   * The viewing frustum is defined by 6 planes.
   * Each plane is represented by a {@link Cartesian4} object, where the x, y, and z components
   * define the unit vector normal to the plane, and the w component is the distance of the
   * plane from the origin/camera position.
   *
   * @alias OrthographicOffCenterFrustum
   * @constructor
   *
   * @param {Object} [options] An object with the following properties:
   * @param {Number} [options.left] The left clipping plane distance.
   * @param {Number} [options.right] The right clipping plane distance.
   * @param {Number} [options.top] The top clipping plane distance.
   * @param {Number} [options.bottom] The bottom clipping plane distance.
   * @param {Number} [options.near=1.0] The near clipping plane distance.
   * @param {Number} [options.far=500000000.0] The far clipping plane distance.
   *
   * @example
   * var maxRadii = ellipsoid.maximumRadius;
   *
   * var frustum = new Cesium.OrthographicOffCenterFrustum();
   * frustum.right = maxRadii * Cesium.Math.PI;
   * frustum.left = -c.frustum.right;
   * frustum.top = c.frustum.right * (canvas.clientHeight / canvas.clientWidth);
   * frustum.bottom = -c.frustum.top;
   * frustum.near = 0.01 * maxRadii;
   * frustum.far = 50.0 * maxRadii;
   */
  function OrthographicOffCenterFrustum(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The left clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.left = options.left;
    this._left = undefined;

    /**
     * The right clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.right = options.right;
    this._right = undefined;

    /**
     * The top clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.top = options.top;
    this._top = undefined;

    /**
     * The bottom clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.bottom = options.bottom;
    this._bottom = undefined;

    /**
     * The distance of the near plane.
     * @type {Number}
     * @default 1.0
     */
    this.near = defaultValue(options.near, 1.0);
    this._near = this.near;

    /**
     * The distance of the far plane.
     * @type {Number}
     * @default 500000000.0;
     */
    this.far = defaultValue(options.far, 500000000.0);
    this._far = this.far;

    this._cullingVolume = new CullingVolume();
    this._orthographicMatrix = new Matrix4();
  }

  function update(frustum) {
    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(frustum.right) ||
      !defined(frustum.left) ||
      !defined(frustum.top) ||
      !defined(frustum.bottom) ||
      !defined(frustum.near) ||
      !defined(frustum.far)
    ) {
      throw new DeveloperError(
        "right, left, top, bottom, near, or far parameters are not set."
      );
    }
    //>>includeEnd('debug');

    if (
      frustum.top !== frustum._top ||
      frustum.bottom !== frustum._bottom ||
      frustum.left !== frustum._left ||
      frustum.right !== frustum._right ||
      frustum.near !== frustum._near ||
      frustum.far !== frustum._far
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (frustum.left > frustum.right) {
        throw new DeveloperError("right must be greater than left.");
      }
      if (frustum.bottom > frustum.top) {
        throw new DeveloperError("top must be greater than bottom.");
      }
      if (frustum.near <= 0 || frustum.near > frustum.far) {
        throw new DeveloperError(
          "near must be greater than zero and less than far."
        );
      }
      //>>includeEnd('debug');

      frustum._left = frustum.left;
      frustum._right = frustum.right;
      frustum._top = frustum.top;
      frustum._bottom = frustum.bottom;
      frustum._near = frustum.near;
      frustum._far = frustum.far;
      frustum._orthographicMatrix = Matrix4.computeOrthographicOffCenter(
        frustum.left,
        frustum.right,
        frustum.bottom,
        frustum.top,
        frustum.near,
        frustum.far,
        frustum._orthographicMatrix
      );
    }
  }

  Object.defineProperties(OrthographicOffCenterFrustum.prototype, {
    /**
     * Gets the orthographic projection matrix computed from the view frustum.
     * @memberof OrthographicOffCenterFrustum.prototype
     * @type {Matrix4}
     * @readonly
     */
    projectionMatrix: {
      get: function () {
        update(this);
        return this._orthographicMatrix;
      },
    },
  });

  var getPlanesRight = new Cartesian3();
  var getPlanesNearCenter = new Cartesian3();
  var getPlanesPoint = new Cartesian3();
  var negateScratch = new Cartesian3();

  /**
   * Creates a culling volume for this frustum.
   *
   * @param {Cartesian3} position The eye position.
   * @param {Cartesian3} direction The view direction.
   * @param {Cartesian3} up The up direction.
   * @returns {CullingVolume} A culling volume at the given position and orientation.
   *
   * @example
   * // Check if a bounding volume intersects the frustum.
   * var cullingVolume = frustum.computeCullingVolume(cameraPosition, cameraDirection, cameraUp);
   * var intersect = cullingVolume.computeVisibility(boundingVolume);
   */
  OrthographicOffCenterFrustum.prototype.computeCullingVolume = function (
    position,
    direction,
    up
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(position)) {
      throw new DeveloperError("position is required.");
    }
    if (!defined(direction)) {
      throw new DeveloperError("direction is required.");
    }
    if (!defined(up)) {
      throw new DeveloperError("up is required.");
    }
    //>>includeEnd('debug');

    var planes = this._cullingVolume.planes;
    var t = this.top;
    var b = this.bottom;
    var r = this.right;
    var l = this.left;
    var n = this.near;
    var f = this.far;

    var right = Cartesian3.cross(direction, up, getPlanesRight);
    Cartesian3.normalize(right, right);
    var nearCenter = getPlanesNearCenter;
    Cartesian3.multiplyByScalar(direction, n, nearCenter);
    Cartesian3.add(position, nearCenter, nearCenter);

    var point = getPlanesPoint;

    // Left plane
    Cartesian3.multiplyByScalar(right, l, point);
    Cartesian3.add(nearCenter, point, point);

    var plane = planes[0];
    if (!defined(plane)) {
      plane = planes[0] = new Cartesian4();
    }
    plane.x = right.x;
    plane.y = right.y;
    plane.z = right.z;
    plane.w = -Cartesian3.dot(right, point);

    // Right plane
    Cartesian3.multiplyByScalar(right, r, point);
    Cartesian3.add(nearCenter, point, point);

    plane = planes[1];
    if (!defined(plane)) {
      plane = planes[1] = new Cartesian4();
    }
    plane.x = -right.x;
    plane.y = -right.y;
    plane.z = -right.z;
    plane.w = -Cartesian3.dot(Cartesian3.negate(right, negateScratch), point);

    // Bottom plane
    Cartesian3.multiplyByScalar(up, b, point);
    Cartesian3.add(nearCenter, point, point);

    plane = planes[2];
    if (!defined(plane)) {
      plane = planes[2] = new Cartesian4();
    }
    plane.x = up.x;
    plane.y = up.y;
    plane.z = up.z;
    plane.w = -Cartesian3.dot(up, point);

    // Top plane
    Cartesian3.multiplyByScalar(up, t, point);
    Cartesian3.add(nearCenter, point, point);

    plane = planes[3];
    if (!defined(plane)) {
      plane = planes[3] = new Cartesian4();
    }
    plane.x = -up.x;
    plane.y = -up.y;
    plane.z = -up.z;
    plane.w = -Cartesian3.dot(Cartesian3.negate(up, negateScratch), point);

    // Near plane
    plane = planes[4];
    if (!defined(plane)) {
      plane = planes[4] = new Cartesian4();
    }
    plane.x = direction.x;
    plane.y = direction.y;
    plane.z = direction.z;
    plane.w = -Cartesian3.dot(direction, nearCenter);

    // Far plane
    Cartesian3.multiplyByScalar(direction, f, point);
    Cartesian3.add(position, point, point);

    plane = planes[5];
    if (!defined(plane)) {
      plane = planes[5] = new Cartesian4();
    }
    plane.x = -direction.x;
    plane.y = -direction.y;
    plane.z = -direction.z;
    plane.w = -Cartesian3.dot(Cartesian3.negate(direction, negateScratch), point);

    return this._cullingVolume;
  };

  /**
   * Returns the pixel's width and height in meters.
   *
   * @param {Number} drawingBufferWidth The width of the drawing buffer.
   * @param {Number} drawingBufferHeight The height of the drawing buffer.
   * @param {Number} distance The distance to the near plane in meters.
   * @param {Number} pixelRatio The scaling factor from pixel space to coordinate space.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new instance of {@link Cartesian2} with the pixel's width and height in the x and y properties, respectively.
   *
   * @exception {DeveloperError} drawingBufferWidth must be greater than zero.
   * @exception {DeveloperError} drawingBufferHeight must be greater than zero.
   * @exception {DeveloperError} pixelRatio must be greater than zero.
   *
   * @example
   * // Example 1
   * // Get the width and height of a pixel.
   * var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 0.0, scene.pixelRatio, new Cesium.Cartesian2());
   */
  OrthographicOffCenterFrustum.prototype.getPixelDimensions = function (
    drawingBufferWidth,
    drawingBufferHeight,
    distance,
    pixelRatio,
    result
  ) {
    update(this);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(drawingBufferWidth) || !defined(drawingBufferHeight)) {
      throw new DeveloperError(
        "Both drawingBufferWidth and drawingBufferHeight are required."
      );
    }
    if (drawingBufferWidth <= 0) {
      throw new DeveloperError("drawingBufferWidth must be greater than zero.");
    }
    if (drawingBufferHeight <= 0) {
      throw new DeveloperError("drawingBufferHeight must be greater than zero.");
    }
    if (!defined(distance)) {
      throw new DeveloperError("distance is required.");
    }
    if (!defined(pixelRatio)) {
      throw new DeveloperError("pixelRatio is required.");
    }
    if (pixelRatio <= 0) {
      throw new DeveloperError("pixelRatio must be greater than zero.");
    }
    if (!defined(result)) {
      throw new DeveloperError("A result object is required.");
    }
    //>>includeEnd('debug');

    var frustumWidth = this.right - this.left;
    var frustumHeight = this.top - this.bottom;
    var pixelWidth = (pixelRatio * frustumWidth) / drawingBufferWidth;
    var pixelHeight = (pixelRatio * frustumHeight) / drawingBufferHeight;

    result.x = pixelWidth;
    result.y = pixelHeight;
    return result;
  };

  /**
   * Returns a duplicate of a OrthographicOffCenterFrustum instance.
   *
   * @param {OrthographicOffCenterFrustum} [result] The object onto which to store the result.
   * @returns {OrthographicOffCenterFrustum} The modified result parameter or a new OrthographicOffCenterFrustum instance if one was not provided.
   */
  OrthographicOffCenterFrustum.prototype.clone = function (result) {
    if (!defined(result)) {
      result = new OrthographicOffCenterFrustum();
    }

    result.left = this.left;
    result.right = this.right;
    result.top = this.top;
    result.bottom = this.bottom;
    result.near = this.near;
    result.far = this.far;

    // force update of clone to compute matrices
    result._left = undefined;
    result._right = undefined;
    result._top = undefined;
    result._bottom = undefined;
    result._near = undefined;
    result._far = undefined;

    return result;
  };

  /**
   * Compares the provided OrthographicOffCenterFrustum componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {OrthographicOffCenterFrustum} [other] The right hand side OrthographicOffCenterFrustum.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  OrthographicOffCenterFrustum.prototype.equals = function (other) {
    return (
      defined(other) &&
      other instanceof OrthographicOffCenterFrustum &&
      this.right === other.right &&
      this.left === other.left &&
      this.top === other.top &&
      this.bottom === other.bottom &&
      this.near === other.near &&
      this.far === other.far
    );
  };

  /**
   * Compares the provided OrthographicOffCenterFrustum componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {OrthographicOffCenterFrustum} other The right hand side OrthographicOffCenterFrustum.
   * @param {Number} relativeEpsilon The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if this and other are within the provided epsilon, <code>false</code> otherwise.
   */
  OrthographicOffCenterFrustum.prototype.equalsEpsilon = function (
    other,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return (
      other === this ||
      (defined(other) &&
        other instanceof OrthographicOffCenterFrustum &&
        CesiumMath.equalsEpsilon(
          this.right,
          other.right,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.left,
          other.left,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.top,
          other.top,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.bottom,
          other.bottom,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.near,
          other.near,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.far,
          other.far,
          relativeEpsilon,
          absoluteEpsilon
        ))
    );
  };

  /**
   * The viewing frustum is defined by 6 planes.
   * Each plane is represented by a {@link Cartesian4} object, where the x, y, and z components
   * define the unit vector normal to the plane, and the w component is the distance of the
   * plane from the origin/camera position.
   *
   * @alias OrthographicFrustum
   * @constructor
   *
   * @param {Object} [options] An object with the following properties:
   * @param {Number} [options.width] The width of the frustum in meters.
   * @param {Number} [options.aspectRatio] The aspect ratio of the frustum's width to it's height.
   * @param {Number} [options.near=1.0] The distance of the near plane.
   * @param {Number} [options.far=500000000.0] The distance of the far plane.
   *
   * @example
   * var maxRadii = ellipsoid.maximumRadius;
   *
   * var frustum = new Cesium.OrthographicFrustum();
   * frustum.near = 0.01 * maxRadii;
   * frustum.far = 50.0 * maxRadii;
   */
  function OrthographicFrustum(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._offCenterFrustum = new OrthographicOffCenterFrustum();

    /**
     * The horizontal width of the frustum in meters.
     * @type {Number}
     * @default undefined
     */
    this.width = options.width;
    this._width = undefined;

    /**
     * The aspect ratio of the frustum's width to it's height.
     * @type {Number}
     * @default undefined
     */
    this.aspectRatio = options.aspectRatio;
    this._aspectRatio = undefined;

    /**
     * The distance of the near plane.
     * @type {Number}
     * @default 1.0
     */
    this.near = defaultValue(options.near, 1.0);
    this._near = this.near;

    /**
     * The distance of the far plane.
     * @type {Number}
     * @default 500000000.0;
     */
    this.far = defaultValue(options.far, 500000000.0);
    this._far = this.far;
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  OrthographicFrustum.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {OrthographicFrustum} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  OrthographicFrustum.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.width;
    array[startingIndex++] = value.aspectRatio;
    array[startingIndex++] = value.near;
    array[startingIndex] = value.far;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {OrthographicFrustum} [result] The object into which to store the result.
   * @returns {OrthographicFrustum} The modified result parameter or a new OrthographicFrustum instance if one was not provided.
   */
  OrthographicFrustum.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new OrthographicFrustum();
    }

    result.width = array[startingIndex++];
    result.aspectRatio = array[startingIndex++];
    result.near = array[startingIndex++];
    result.far = array[startingIndex];

    return result;
  };

  function update$1(frustum) {
    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(frustum.width) ||
      !defined(frustum.aspectRatio) ||
      !defined(frustum.near) ||
      !defined(frustum.far)
    ) {
      throw new DeveloperError(
        "width, aspectRatio, near, or far parameters are not set."
      );
    }
    //>>includeEnd('debug');

    var f = frustum._offCenterFrustum;

    if (
      frustum.width !== frustum._width ||
      frustum.aspectRatio !== frustum._aspectRatio ||
      frustum.near !== frustum._near ||
      frustum.far !== frustum._far
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (frustum.aspectRatio < 0) {
        throw new DeveloperError("aspectRatio must be positive.");
      }
      if (frustum.near < 0 || frustum.near > frustum.far) {
        throw new DeveloperError(
          "near must be greater than zero and less than far."
        );
      }
      //>>includeEnd('debug');

      frustum._aspectRatio = frustum.aspectRatio;
      frustum._width = frustum.width;
      frustum._near = frustum.near;
      frustum._far = frustum.far;

      var ratio = 1.0 / frustum.aspectRatio;
      f.right = frustum.width * 0.5;
      f.left = -f.right;
      f.top = ratio * f.right;
      f.bottom = -f.top;
      f.near = frustum.near;
      f.far = frustum.far;
    }
  }

  Object.defineProperties(OrthographicFrustum.prototype, {
    /**
     * Gets the orthographic projection matrix computed from the view frustum.
     * @memberof OrthographicFrustum.prototype
     * @type {Matrix4}
     * @readonly
     */
    projectionMatrix: {
      get: function () {
        update$1(this);
        return this._offCenterFrustum.projectionMatrix;
      },
    },
  });

  /**
   * Creates a culling volume for this frustum.
   *
   * @param {Cartesian3} position The eye position.
   * @param {Cartesian3} direction The view direction.
   * @param {Cartesian3} up The up direction.
   * @returns {CullingVolume} A culling volume at the given position and orientation.
   *
   * @example
   * // Check if a bounding volume intersects the frustum.
   * var cullingVolume = frustum.computeCullingVolume(cameraPosition, cameraDirection, cameraUp);
   * var intersect = cullingVolume.computeVisibility(boundingVolume);
   */
  OrthographicFrustum.prototype.computeCullingVolume = function (
    position,
    direction,
    up
  ) {
    update$1(this);
    return this._offCenterFrustum.computeCullingVolume(position, direction, up);
  };

  /**
   * Returns the pixel's width and height in meters.
   *
   * @param {Number} drawingBufferWidth The width of the drawing buffer.
   * @param {Number} drawingBufferHeight The height of the drawing buffer.
   * @param {Number} distance The distance to the near plane in meters.
   * @param {Number} pixelRatio The scaling factor from pixel space to coordinate space.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new instance of {@link Cartesian2} with the pixel's width and height in the x and y properties, respectively.
   *
   * @exception {DeveloperError} drawingBufferWidth must be greater than zero.
   * @exception {DeveloperError} drawingBufferHeight must be greater than zero.
   * @exception {DeveloperError} pixelRatio must be greater than zero.
   *
   * @example
   * // Example 1
   * // Get the width and height of a pixel.
   * var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 0.0, scene.pixelRatio, new Cesium.Cartesian2());
   */
  OrthographicFrustum.prototype.getPixelDimensions = function (
    drawingBufferWidth,
    drawingBufferHeight,
    distance,
    pixelRatio,
    result
  ) {
    update$1(this);
    return this._offCenterFrustum.getPixelDimensions(
      drawingBufferWidth,
      drawingBufferHeight,
      distance,
      pixelRatio,
      result
    );
  };

  /**
   * Returns a duplicate of a OrthographicFrustum instance.
   *
   * @param {OrthographicFrustum} [result] The object onto which to store the result.
   * @returns {OrthographicFrustum} The modified result parameter or a new OrthographicFrustum instance if one was not provided.
   */
  OrthographicFrustum.prototype.clone = function (result) {
    if (!defined(result)) {
      result = new OrthographicFrustum();
    }

    result.aspectRatio = this.aspectRatio;
    result.width = this.width;
    result.near = this.near;
    result.far = this.far;

    // force update of clone to compute matrices
    result._aspectRatio = undefined;
    result._width = undefined;
    result._near = undefined;
    result._far = undefined;

    this._offCenterFrustum.clone(result._offCenterFrustum);

    return result;
  };

  /**
   * Compares the provided OrthographicFrustum componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {OrthographicFrustum} [other] The right hand side OrthographicFrustum.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  OrthographicFrustum.prototype.equals = function (other) {
    if (!defined(other) || !(other instanceof OrthographicFrustum)) {
      return false;
    }

    update$1(this);
    update$1(other);

    return (
      this.width === other.width &&
      this.aspectRatio === other.aspectRatio &&
      this._offCenterFrustum.equals(other._offCenterFrustum)
    );
  };

  /**
   * Compares the provided OrthographicFrustum componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {OrthographicFrustum} other The right hand side OrthographicFrustum.
   * @param {Number} relativeEpsilon The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if this and other are within the provided epsilon, <code>false</code> otherwise.
   */
  OrthographicFrustum.prototype.equalsEpsilon = function (
    other,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    if (!defined(other) || !(other instanceof OrthographicFrustum)) {
      return false;
    }

    update$1(this);
    update$1(other);

    return (
      CesiumMath.equalsEpsilon(
        this.width,
        other.width,
        relativeEpsilon,
        absoluteEpsilon
      ) &&
      CesiumMath.equalsEpsilon(
        this.aspectRatio,
        other.aspectRatio,
        relativeEpsilon,
        absoluteEpsilon
      ) &&
      this._offCenterFrustum.equalsEpsilon(
        other._offCenterFrustum,
        relativeEpsilon,
        absoluteEpsilon
      )
    );
  };

  /**
   * The viewing frustum is defined by 6 planes.
   * Each plane is represented by a {@link Cartesian4} object, where the x, y, and z components
   * define the unit vector normal to the plane, and the w component is the distance of the
   * plane from the origin/camera position.
   *
   * @alias PerspectiveOffCenterFrustum
   * @constructor
   *
   * @param {Object} [options] An object with the following properties:
   * @param {Number} [options.left] The left clipping plane distance.
   * @param {Number} [options.right] The right clipping plane distance.
   * @param {Number} [options.top] The top clipping plane distance.
   * @param {Number} [options.bottom] The bottom clipping plane distance.
   * @param {Number} [options.near=1.0] The near clipping plane distance.
   * @param {Number} [options.far=500000000.0] The far clipping plane distance.
   *
   * @example
   * var frustum = new Cesium.PerspectiveOffCenterFrustum({
   *     left : -1.0,
   *     right : 1.0,
   *     top : 1.0,
   *     bottom : -1.0,
   *     near : 1.0,
   *     far : 100.0
   * });
   *
   * @see PerspectiveFrustum
   */
  function PerspectiveOffCenterFrustum(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * Defines the left clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.left = options.left;
    this._left = undefined;

    /**
     * Defines the right clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.right = options.right;
    this._right = undefined;

    /**
     * Defines the top clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.top = options.top;
    this._top = undefined;

    /**
     * Defines the bottom clipping plane.
     * @type {Number}
     * @default undefined
     */
    this.bottom = options.bottom;
    this._bottom = undefined;

    /**
     * The distance of the near plane.
     * @type {Number}
     * @default 1.0
     */
    this.near = defaultValue(options.near, 1.0);
    this._near = this.near;

    /**
     * The distance of the far plane.
     * @type {Number}
     * @default 500000000.0
     */
    this.far = defaultValue(options.far, 500000000.0);
    this._far = this.far;

    this._cullingVolume = new CullingVolume();
    this._perspectiveMatrix = new Matrix4();
    this._infinitePerspective = new Matrix4();
  }

  function update$2(frustum) {
    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(frustum.right) ||
      !defined(frustum.left) ||
      !defined(frustum.top) ||
      !defined(frustum.bottom) ||
      !defined(frustum.near) ||
      !defined(frustum.far)
    ) {
      throw new DeveloperError(
        "right, left, top, bottom, near, or far parameters are not set."
      );
    }
    //>>includeEnd('debug');

    var t = frustum.top;
    var b = frustum.bottom;
    var r = frustum.right;
    var l = frustum.left;
    var n = frustum.near;
    var f = frustum.far;

    if (
      t !== frustum._top ||
      b !== frustum._bottom ||
      l !== frustum._left ||
      r !== frustum._right ||
      n !== frustum._near ||
      f !== frustum._far
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (frustum.near <= 0 || frustum.near > frustum.far) {
        throw new DeveloperError(
          "near must be greater than zero and less than far."
        );
      }
      //>>includeEnd('debug');

      frustum._left = l;
      frustum._right = r;
      frustum._top = t;
      frustum._bottom = b;
      frustum._near = n;
      frustum._far = f;
      frustum._perspectiveMatrix = Matrix4.computePerspectiveOffCenter(
        l,
        r,
        b,
        t,
        n,
        f,
        frustum._perspectiveMatrix
      );
      frustum._infinitePerspective = Matrix4.computeInfinitePerspectiveOffCenter(
        l,
        r,
        b,
        t,
        n,
        frustum._infinitePerspective
      );
    }
  }

  Object.defineProperties(PerspectiveOffCenterFrustum.prototype, {
    /**
     * Gets the perspective projection matrix computed from the view frustum.
     * @memberof PerspectiveOffCenterFrustum.prototype
     * @type {Matrix4}
     * @readonly
     *
     * @see PerspectiveOffCenterFrustum#infiniteProjectionMatrix
     */
    projectionMatrix: {
      get: function () {
        update$2(this);
        return this._perspectiveMatrix;
      },
    },

    /**
     * Gets the perspective projection matrix computed from the view frustum with an infinite far plane.
     * @memberof PerspectiveOffCenterFrustum.prototype
     * @type {Matrix4}
     * @readonly
     *
     * @see PerspectiveOffCenterFrustum#projectionMatrix
     */
    infiniteProjectionMatrix: {
      get: function () {
        update$2(this);
        return this._infinitePerspective;
      },
    },
  });

  var getPlanesRight$1 = new Cartesian3();
  var getPlanesNearCenter$1 = new Cartesian3();
  var getPlanesFarCenter = new Cartesian3();
  var getPlanesNormal = new Cartesian3();
  /**
   * Creates a culling volume for this frustum.
   *
   * @param {Cartesian3} position The eye position.
   * @param {Cartesian3} direction The view direction.
   * @param {Cartesian3} up The up direction.
   * @returns {CullingVolume} A culling volume at the given position and orientation.
   *
   * @example
   * // Check if a bounding volume intersects the frustum.
   * var cullingVolume = frustum.computeCullingVolume(cameraPosition, cameraDirection, cameraUp);
   * var intersect = cullingVolume.computeVisibility(boundingVolume);
   */
  PerspectiveOffCenterFrustum.prototype.computeCullingVolume = function (
    position,
    direction,
    up
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(position)) {
      throw new DeveloperError("position is required.");
    }

    if (!defined(direction)) {
      throw new DeveloperError("direction is required.");
    }

    if (!defined(up)) {
      throw new DeveloperError("up is required.");
    }
    //>>includeEnd('debug');

    var planes = this._cullingVolume.planes;

    var t = this.top;
    var b = this.bottom;
    var r = this.right;
    var l = this.left;
    var n = this.near;
    var f = this.far;

    var right = Cartesian3.cross(direction, up, getPlanesRight$1);

    var nearCenter = getPlanesNearCenter$1;
    Cartesian3.multiplyByScalar(direction, n, nearCenter);
    Cartesian3.add(position, nearCenter, nearCenter);

    var farCenter = getPlanesFarCenter;
    Cartesian3.multiplyByScalar(direction, f, farCenter);
    Cartesian3.add(position, farCenter, farCenter);

    var normal = getPlanesNormal;

    //Left plane computation
    Cartesian3.multiplyByScalar(right, l, normal);
    Cartesian3.add(nearCenter, normal, normal);
    Cartesian3.subtract(normal, position, normal);
    Cartesian3.normalize(normal, normal);
    Cartesian3.cross(normal, up, normal);
    Cartesian3.normalize(normal, normal);

    var plane = planes[0];
    if (!defined(plane)) {
      plane = planes[0] = new Cartesian4();
    }
    plane.x = normal.x;
    plane.y = normal.y;
    plane.z = normal.z;
    plane.w = -Cartesian3.dot(normal, position);

    //Right plane computation
    Cartesian3.multiplyByScalar(right, r, normal);
    Cartesian3.add(nearCenter, normal, normal);
    Cartesian3.subtract(normal, position, normal);
    Cartesian3.cross(up, normal, normal);
    Cartesian3.normalize(normal, normal);

    plane = planes[1];
    if (!defined(plane)) {
      plane = planes[1] = new Cartesian4();
    }
    plane.x = normal.x;
    plane.y = normal.y;
    plane.z = normal.z;
    plane.w = -Cartesian3.dot(normal, position);

    //Bottom plane computation
    Cartesian3.multiplyByScalar(up, b, normal);
    Cartesian3.add(nearCenter, normal, normal);
    Cartesian3.subtract(normal, position, normal);
    Cartesian3.cross(right, normal, normal);
    Cartesian3.normalize(normal, normal);

    plane = planes[2];
    if (!defined(plane)) {
      plane = planes[2] = new Cartesian4();
    }
    plane.x = normal.x;
    plane.y = normal.y;
    plane.z = normal.z;
    plane.w = -Cartesian3.dot(normal, position);

    //Top plane computation
    Cartesian3.multiplyByScalar(up, t, normal);
    Cartesian3.add(nearCenter, normal, normal);
    Cartesian3.subtract(normal, position, normal);
    Cartesian3.cross(normal, right, normal);
    Cartesian3.normalize(normal, normal);

    plane = planes[3];
    if (!defined(plane)) {
      plane = planes[3] = new Cartesian4();
    }
    plane.x = normal.x;
    plane.y = normal.y;
    plane.z = normal.z;
    plane.w = -Cartesian3.dot(normal, position);

    //Near plane computation
    plane = planes[4];
    if (!defined(plane)) {
      plane = planes[4] = new Cartesian4();
    }
    plane.x = direction.x;
    plane.y = direction.y;
    plane.z = direction.z;
    plane.w = -Cartesian3.dot(direction, nearCenter);

    //Far plane computation
    Cartesian3.negate(direction, normal);

    plane = planes[5];
    if (!defined(plane)) {
      plane = planes[5] = new Cartesian4();
    }
    plane.x = normal.x;
    plane.y = normal.y;
    plane.z = normal.z;
    plane.w = -Cartesian3.dot(normal, farCenter);

    return this._cullingVolume;
  };

  /**
   * Returns the pixel's width and height in meters.
   *
   * @param {Number} drawingBufferWidth The width of the drawing buffer.
   * @param {Number} drawingBufferHeight The height of the drawing buffer.
   * @param {Number} distance The distance to the near plane in meters.
   * @param {Number} pixelRatio The scaling factor from pixel space to coordinate space.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new instance of {@link Cartesian2} with the pixel's width and height in the x and y properties, respectively.
   *
   * @exception {DeveloperError} drawingBufferWidth must be greater than zero.
   * @exception {DeveloperError} drawingBufferHeight must be greater than zero.
   * @exception {DeveloperError} pixelRatio must be greater than zero.
   *
   * @example
   * // Example 1
   * // Get the width and height of a pixel.
   * var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 1.0, scene.pixelRatio, new Cesium.Cartesian2());
   *
   * @example
   * // Example 2
   * // Get the width and height of a pixel if the near plane was set to 'distance'.
   * // For example, get the size of a pixel of an image on a billboard.
   * var position = camera.position;
   * var direction = camera.direction;
   * var toCenter = Cesium.Cartesian3.subtract(primitive.boundingVolume.center, position, new Cesium.Cartesian3());      // vector from camera to a primitive
   * var toCenterProj = Cesium.Cartesian3.multiplyByScalar(direction, Cesium.Cartesian3.dot(direction, toCenter), new Cesium.Cartesian3()); // project vector onto camera direction vector
   * var distance = Cesium.Cartesian3.magnitude(toCenterProj);
   * var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, distance, scene.pixelRatio, new Cesium.Cartesian2());
   */
  PerspectiveOffCenterFrustum.prototype.getPixelDimensions = function (
    drawingBufferWidth,
    drawingBufferHeight,
    distance,
    pixelRatio,
    result
  ) {
    update$2(this);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(drawingBufferWidth) || !defined(drawingBufferHeight)) {
      throw new DeveloperError(
        "Both drawingBufferWidth and drawingBufferHeight are required."
      );
    }
    if (drawingBufferWidth <= 0) {
      throw new DeveloperError("drawingBufferWidth must be greater than zero.");
    }
    if (drawingBufferHeight <= 0) {
      throw new DeveloperError("drawingBufferHeight must be greater than zero.");
    }
    if (!defined(distance)) {
      throw new DeveloperError("distance is required.");
    }
    if (!defined(pixelRatio)) {
      throw new DeveloperError("pixelRatio is required");
    }
    if (pixelRatio <= 0) {
      throw new DeveloperError("pixelRatio must be greater than zero.");
    }
    if (!defined(result)) {
      throw new DeveloperError("A result object is required.");
    }
    //>>includeEnd('debug');

    var inverseNear = 1.0 / this.near;
    var tanTheta = this.top * inverseNear;
    var pixelHeight =
      (2.0 * pixelRatio * distance * tanTheta) / drawingBufferHeight;
    tanTheta = this.right * inverseNear;
    var pixelWidth =
      (2.0 * pixelRatio * distance * tanTheta) / drawingBufferWidth;

    result.x = pixelWidth;
    result.y = pixelHeight;
    return result;
  };

  /**
   * Returns a duplicate of a PerspectiveOffCenterFrustum instance.
   *
   * @param {PerspectiveOffCenterFrustum} [result] The object onto which to store the result.
   * @returns {PerspectiveOffCenterFrustum} The modified result parameter or a new PerspectiveFrustum instance if one was not provided.
   */
  PerspectiveOffCenterFrustum.prototype.clone = function (result) {
    if (!defined(result)) {
      result = new PerspectiveOffCenterFrustum();
    }

    result.right = this.right;
    result.left = this.left;
    result.top = this.top;
    result.bottom = this.bottom;
    result.near = this.near;
    result.far = this.far;

    // force update of clone to compute matrices
    result._left = undefined;
    result._right = undefined;
    result._top = undefined;
    result._bottom = undefined;
    result._near = undefined;
    result._far = undefined;

    return result;
  };

  /**
   * Compares the provided PerspectiveOffCenterFrustum componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {PerspectiveOffCenterFrustum} [other] The right hand side PerspectiveOffCenterFrustum.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  PerspectiveOffCenterFrustum.prototype.equals = function (other) {
    return (
      defined(other) &&
      other instanceof PerspectiveOffCenterFrustum &&
      this.right === other.right &&
      this.left === other.left &&
      this.top === other.top &&
      this.bottom === other.bottom &&
      this.near === other.near &&
      this.far === other.far
    );
  };

  /**
   * Compares the provided PerspectiveOffCenterFrustum componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {PerspectiveOffCenterFrustum} other The right hand side PerspectiveOffCenterFrustum.
   * @param {Number} relativeEpsilon The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if this and other are within the provided epsilon, <code>false</code> otherwise.
   */
  PerspectiveOffCenterFrustum.prototype.equalsEpsilon = function (
    other,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    return (
      other === this ||
      (defined(other) &&
        other instanceof PerspectiveOffCenterFrustum &&
        CesiumMath.equalsEpsilon(
          this.right,
          other.right,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.left,
          other.left,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.top,
          other.top,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.bottom,
          other.bottom,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.near,
          other.near,
          relativeEpsilon,
          absoluteEpsilon
        ) &&
        CesiumMath.equalsEpsilon(
          this.far,
          other.far,
          relativeEpsilon,
          absoluteEpsilon
        ))
    );
  };

  /**
   * The viewing frustum is defined by 6 planes.
   * Each plane is represented by a {@link Cartesian4} object, where the x, y, and z components
   * define the unit vector normal to the plane, and the w component is the distance of the
   * plane from the origin/camera position.
   *
   * @alias PerspectiveFrustum
   * @constructor
   *
   * @param {Object} [options] An object with the following properties:
   * @param {Number} [options.fov] The angle of the field of view (FOV), in radians.
   * @param {Number} [options.aspectRatio] The aspect ratio of the frustum's width to it's height.
   * @param {Number} [options.near=1.0] The distance of the near plane.
   * @param {Number} [options.far=500000000.0] The distance of the far plane.
   * @param {Number} [options.xOffset=0.0] The offset in the x direction.
   * @param {Number} [options.yOffset=0.0] The offset in the y direction.
   *
   * @example
   * var frustum = new Cesium.PerspectiveFrustum({
   *     fov : Cesium.Math.PI_OVER_THREE,
   *     aspectRatio : canvas.clientWidth / canvas.clientHeight
   *     near : 1.0,
   *     far : 1000.0
   * });
   *
   * @see PerspectiveOffCenterFrustum
   */
  function PerspectiveFrustum(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._offCenterFrustum = new PerspectiveOffCenterFrustum();

    /**
     * The angle of the field of view (FOV), in radians.  This angle will be used
     * as the horizontal FOV if the width is greater than the height, otherwise
     * it will be the vertical FOV.
     * @type {Number}
     * @default undefined
     */
    this.fov = options.fov;
    this._fov = undefined;
    this._fovy = undefined;

    this._sseDenominator = undefined;

    /**
     * The aspect ratio of the frustum's width to it's height.
     * @type {Number}
     * @default undefined
     */
    this.aspectRatio = options.aspectRatio;
    this._aspectRatio = undefined;

    /**
     * The distance of the near plane.
     * @type {Number}
     * @default 1.0
     */
    this.near = defaultValue(options.near, 1.0);
    this._near = this.near;

    /**
     * The distance of the far plane.
     * @type {Number}
     * @default 500000000.0
     */
    this.far = defaultValue(options.far, 500000000.0);
    this._far = this.far;

    /**
     * Offsets the frustum in the x direction.
     * @type {Number}
     * @default 0.0
     */
    this.xOffset = defaultValue(options.xOffset, 0.0);
    this._xOffset = this.xOffset;

    /**
     * Offsets the frustum in the y direction.
     * @type {Number}
     * @default 0.0
     */
    this.yOffset = defaultValue(options.yOffset, 0.0);
    this._yOffset = this.yOffset;
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  PerspectiveFrustum.packedLength = 6;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PerspectiveFrustum} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PerspectiveFrustum.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.fov;
    array[startingIndex++] = value.aspectRatio;
    array[startingIndex++] = value.near;
    array[startingIndex++] = value.far;
    array[startingIndex++] = value.xOffset;
    array[startingIndex] = value.yOffset;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PerspectiveFrustum} [result] The object into which to store the result.
   * @returns {PerspectiveFrustum} The modified result parameter or a new PerspectiveFrustum instance if one was not provided.
   */
  PerspectiveFrustum.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new PerspectiveFrustum();
    }

    result.fov = array[startingIndex++];
    result.aspectRatio = array[startingIndex++];
    result.near = array[startingIndex++];
    result.far = array[startingIndex++];
    result.xOffset = array[startingIndex++];
    result.yOffset = array[startingIndex];

    return result;
  };

  function update$3(frustum) {
    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(frustum.fov) ||
      !defined(frustum.aspectRatio) ||
      !defined(frustum.near) ||
      !defined(frustum.far)
    ) {
      throw new DeveloperError(
        "fov, aspectRatio, near, or far parameters are not set."
      );
    }
    //>>includeEnd('debug');

    var f = frustum._offCenterFrustum;

    if (
      frustum.fov !== frustum._fov ||
      frustum.aspectRatio !== frustum._aspectRatio ||
      frustum.near !== frustum._near ||
      frustum.far !== frustum._far ||
      frustum.xOffset !== frustum._xOffset ||
      frustum.yOffset !== frustum._yOffset
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (frustum.fov < 0 || frustum.fov >= Math.PI) {
        throw new DeveloperError("fov must be in the range [0, PI).");
      }

      if (frustum.aspectRatio < 0) {
        throw new DeveloperError("aspectRatio must be positive.");
      }

      if (frustum.near < 0 || frustum.near > frustum.far) {
        throw new DeveloperError(
          "near must be greater than zero and less than far."
        );
      }
      //>>includeEnd('debug');

      frustum._aspectRatio = frustum.aspectRatio;
      frustum._fov = frustum.fov;
      frustum._fovy =
        frustum.aspectRatio <= 1
          ? frustum.fov
          : Math.atan(Math.tan(frustum.fov * 0.5) / frustum.aspectRatio) * 2.0;
      frustum._near = frustum.near;
      frustum._far = frustum.far;
      frustum._sseDenominator = 2.0 * Math.tan(0.5 * frustum._fovy);
      frustum._xOffset = frustum.xOffset;
      frustum._yOffset = frustum.yOffset;

      f.top = frustum.near * Math.tan(0.5 * frustum._fovy);
      f.bottom = -f.top;
      f.right = frustum.aspectRatio * f.top;
      f.left = -f.right;
      f.near = frustum.near;
      f.far = frustum.far;

      f.right += frustum.xOffset;
      f.left += frustum.xOffset;
      f.top += frustum.yOffset;
      f.bottom += frustum.yOffset;
    }
  }

  Object.defineProperties(PerspectiveFrustum.prototype, {
    /**
     * Gets the perspective projection matrix computed from the view frustum.
     * @memberof PerspectiveFrustum.prototype
     * @type {Matrix4}
     * @readonly
     *
     * @see PerspectiveFrustum#infiniteProjectionMatrix
     */
    projectionMatrix: {
      get: function () {
        update$3(this);
        return this._offCenterFrustum.projectionMatrix;
      },
    },

    /**
     * The perspective projection matrix computed from the view frustum with an infinite far plane.
     * @memberof PerspectiveFrustum.prototype
     * @type {Matrix4}
     * @readonly
     *
     * @see PerspectiveFrustum#projectionMatrix
     */
    infiniteProjectionMatrix: {
      get: function () {
        update$3(this);
        return this._offCenterFrustum.infiniteProjectionMatrix;
      },
    },

    /**
     * Gets the angle of the vertical field of view, in radians.
     * @memberof PerspectiveFrustum.prototype
     * @type {Number}
     * @readonly
     * @default undefined
     */
    fovy: {
      get: function () {
        update$3(this);
        return this._fovy;
      },
    },

    /**
     * @readonly
     * @private
     */
    sseDenominator: {
      get: function () {
        update$3(this);
        return this._sseDenominator;
      },
    },
  });

  /**
   * Creates a culling volume for this frustum.
   *
   * @param {Cartesian3} position The eye position.
   * @param {Cartesian3} direction The view direction.
   * @param {Cartesian3} up The up direction.
   * @returns {CullingVolume} A culling volume at the given position and orientation.
   *
   * @example
   * // Check if a bounding volume intersects the frustum.
   * var cullingVolume = frustum.computeCullingVolume(cameraPosition, cameraDirection, cameraUp);
   * var intersect = cullingVolume.computeVisibility(boundingVolume);
   */
  PerspectiveFrustum.prototype.computeCullingVolume = function (
    position,
    direction,
    up
  ) {
    update$3(this);
    return this._offCenterFrustum.computeCullingVolume(position, direction, up);
  };

  /**
   * Returns the pixel's width and height in meters.
   *
   * @param {Number} drawingBufferWidth The width of the drawing buffer.
   * @param {Number} drawingBufferHeight The height of the drawing buffer.
   * @param {Number} distance The distance to the near plane in meters.
   * @param {Number} pixelRatio The scaling factor from pixel space to coordinate space.
   * @param {Cartesian2} result The object onto which to store the result.
   * @returns {Cartesian2} The modified result parameter or a new instance of {@link Cartesian2} with the pixel's width and height in the x and y properties, respectively.
   *
   * @exception {DeveloperError} drawingBufferWidth must be greater than zero.
   * @exception {DeveloperError} drawingBufferHeight must be greater than zero.
   * @exception {DeveloperError} pixelRatio must be greater than zero.
   *
   * @example
   * // Example 1
   * // Get the width and height of a pixel.
   * var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 1.0, scene.pixelRatio, new Cesium.Cartesian2());
   *
   * @example
   * // Example 2
   * // Get the width and height of a pixel if the near plane was set to 'distance'.
   * // For example, get the size of a pixel of an image on a billboard.
   * var position = camera.position;
   * var direction = camera.direction;
   * var toCenter = Cesium.Cartesian3.subtract(primitive.boundingVolume.center, position, new Cesium.Cartesian3());      // vector from camera to a primitive
   * var toCenterProj = Cesium.Cartesian3.multiplyByScalar(direction, Cesium.Cartesian3.dot(direction, toCenter), new Cesium.Cartesian3()); // project vector onto camera direction vector
   * var distance = Cesium.Cartesian3.magnitude(toCenterProj);
   * var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, distance, scene.pixelRatio, new Cesium.Cartesian2());
   */
  PerspectiveFrustum.prototype.getPixelDimensions = function (
    drawingBufferWidth,
    drawingBufferHeight,
    distance,
    pixelRatio,
    result
  ) {
    update$3(this);
    return this._offCenterFrustum.getPixelDimensions(
      drawingBufferWidth,
      drawingBufferHeight,
      distance,
      pixelRatio,
      result
    );
  };

  /**
   * Returns a duplicate of a PerspectiveFrustum instance.
   *
   * @param {PerspectiveFrustum} [result] The object onto which to store the result.
   * @returns {PerspectiveFrustum} The modified result parameter or a new PerspectiveFrustum instance if one was not provided.
   */
  PerspectiveFrustum.prototype.clone = function (result) {
    if (!defined(result)) {
      result = new PerspectiveFrustum();
    }

    result.aspectRatio = this.aspectRatio;
    result.fov = this.fov;
    result.near = this.near;
    result.far = this.far;

    // force update of clone to compute matrices
    result._aspectRatio = undefined;
    result._fov = undefined;
    result._near = undefined;
    result._far = undefined;

    this._offCenterFrustum.clone(result._offCenterFrustum);

    return result;
  };

  /**
   * Compares the provided PerspectiveFrustum componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {PerspectiveFrustum} [other] The right hand side PerspectiveFrustum.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  PerspectiveFrustum.prototype.equals = function (other) {
    if (!defined(other) || !(other instanceof PerspectiveFrustum)) {
      return false;
    }

    update$3(this);
    update$3(other);

    return (
      this.fov === other.fov &&
      this.aspectRatio === other.aspectRatio &&
      this._offCenterFrustum.equals(other._offCenterFrustum)
    );
  };

  /**
   * Compares the provided PerspectiveFrustum componentwise and returns
   * <code>true</code> if they pass an absolute or relative tolerance test,
   * <code>false</code> otherwise.
   *
   * @param {PerspectiveFrustum} other The right hand side PerspectiveFrustum.
   * @param {Number} relativeEpsilon The relative epsilon tolerance to use for equality testing.
   * @param {Number} [absoluteEpsilon=relativeEpsilon] The absolute epsilon tolerance to use for equality testing.
   * @returns {Boolean} <code>true</code> if this and other are within the provided epsilon, <code>false</code> otherwise.
   */
  PerspectiveFrustum.prototype.equalsEpsilon = function (
    other,
    relativeEpsilon,
    absoluteEpsilon
  ) {
    if (!defined(other) || !(other instanceof PerspectiveFrustum)) {
      return false;
    }

    update$3(this);
    update$3(other);

    return (
      CesiumMath.equalsEpsilon(
        this.fov,
        other.fov,
        relativeEpsilon,
        absoluteEpsilon
      ) &&
      CesiumMath.equalsEpsilon(
        this.aspectRatio,
        other.aspectRatio,
        relativeEpsilon,
        absoluteEpsilon
      ) &&
      this._offCenterFrustum.equalsEpsilon(
        other._offCenterFrustum,
        relativeEpsilon,
        absoluteEpsilon
      )
    );
  };

  var PERSPECTIVE = 0;
  var ORTHOGRAPHIC = 1;

  /**
   * Describes a frustum at the given the origin and orientation.
   *
   * @alias FrustumGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {PerspectiveFrustum|OrthographicFrustum} options.frustum The frustum.
   * @param {Cartesian3} options.origin The origin of the frustum.
   * @param {Quaternion} options.orientation The orientation of the frustum.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   */
  function FrustumGeometry(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.frustum", options.frustum);
    Check.typeOf.object("options.origin", options.origin);
    Check.typeOf.object("options.orientation", options.orientation);
    //>>includeEnd('debug');

    var frustum = options.frustum;
    var orientation = options.orientation;
    var origin = options.origin;
    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);

    // This is private because it is used by DebugCameraPrimitive to draw a multi-frustum by
    // creating multiple FrustumGeometrys. This way the near plane of one frustum doesn't overlap
    // the far plane of another.
    var drawNearPlane = defaultValue(options._drawNearPlane, true);

    var frustumType;
    var frustumPackedLength;
    if (frustum instanceof PerspectiveFrustum) {
      frustumType = PERSPECTIVE;
      frustumPackedLength = PerspectiveFrustum.packedLength;
    } else if (frustum instanceof OrthographicFrustum) {
      frustumType = ORTHOGRAPHIC;
      frustumPackedLength = OrthographicFrustum.packedLength;
    }

    this._frustumType = frustumType;
    this._frustum = frustum.clone();
    this._origin = Cartesian3.clone(origin);
    this._orientation = Quaternion.clone(orientation);
    this._drawNearPlane = drawNearPlane;
    this._vertexFormat = vertexFormat;
    this._workerName = "createFrustumGeometry";

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      2 +
      frustumPackedLength +
      Cartesian3.packedLength +
      Quaternion.packedLength +
      VertexFormat.packedLength;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {FrustumGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  FrustumGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var frustumType = value._frustumType;
    var frustum = value._frustum;

    array[startingIndex++] = frustumType;

    if (frustumType === PERSPECTIVE) {
      PerspectiveFrustum.pack(frustum, array, startingIndex);
      startingIndex += PerspectiveFrustum.packedLength;
    } else {
      OrthographicFrustum.pack(frustum, array, startingIndex);
      startingIndex += OrthographicFrustum.packedLength;
    }

    Cartesian3.pack(value._origin, array, startingIndex);
    startingIndex += Cartesian3.packedLength;
    Quaternion.pack(value._orientation, array, startingIndex);
    startingIndex += Quaternion.packedLength;
    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;
    array[startingIndex] = value._drawNearPlane ? 1.0 : 0.0;

    return array;
  };

  var scratchPackPerspective = new PerspectiveFrustum();
  var scratchPackOrthographic = new OrthographicFrustum();
  var scratchPackQuaternion = new Quaternion();
  var scratchPackorigin = new Cartesian3();
  var scratchVertexFormat$6 = new VertexFormat();

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {FrustumGeometry} [result] The object into which to store the result.
   */
  FrustumGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var frustumType = array[startingIndex++];

    var frustum;
    if (frustumType === PERSPECTIVE) {
      frustum = PerspectiveFrustum.unpack(
        array,
        startingIndex,
        scratchPackPerspective
      );
      startingIndex += PerspectiveFrustum.packedLength;
    } else {
      frustum = OrthographicFrustum.unpack(
        array,
        startingIndex,
        scratchPackOrthographic
      );
      startingIndex += OrthographicFrustum.packedLength;
    }

    var origin = Cartesian3.unpack(array, startingIndex, scratchPackorigin);
    startingIndex += Cartesian3.packedLength;
    var orientation = Quaternion.unpack(
      array,
      startingIndex,
      scratchPackQuaternion
    );
    startingIndex += Quaternion.packedLength;
    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$6
    );
    startingIndex += VertexFormat.packedLength;
    var drawNearPlane = array[startingIndex] === 1.0;

    if (!defined(result)) {
      return new FrustumGeometry({
        frustum: frustum,
        origin: origin,
        orientation: orientation,
        vertexFormat: vertexFormat,
        _drawNearPlane: drawNearPlane,
      });
    }

    var frustumResult =
      frustumType === result._frustumType ? result._frustum : undefined;
    result._frustum = frustum.clone(frustumResult);

    result._frustumType = frustumType;
    result._origin = Cartesian3.clone(origin, result._origin);
    result._orientation = Quaternion.clone(orientation, result._orientation);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._drawNearPlane = drawNearPlane;

    return result;
  };

  function getAttributes(
    offset,
    normals,
    tangents,
    bitangents,
    st,
    normal,
    tangent,
    bitangent
  ) {
    var stOffset = (offset / 3) * 2;

    for (var i = 0; i < 4; ++i) {
      if (defined(normals)) {
        normals[offset] = normal.x;
        normals[offset + 1] = normal.y;
        normals[offset + 2] = normal.z;
      }
      if (defined(tangents)) {
        tangents[offset] = tangent.x;
        tangents[offset + 1] = tangent.y;
        tangents[offset + 2] = tangent.z;
      }
      if (defined(bitangents)) {
        bitangents[offset] = bitangent.x;
        bitangents[offset + 1] = bitangent.y;
        bitangents[offset + 2] = bitangent.z;
      }
      offset += 3;
    }

    st[stOffset] = 0.0;
    st[stOffset + 1] = 0.0;
    st[stOffset + 2] = 1.0;
    st[stOffset + 3] = 0.0;
    st[stOffset + 4] = 1.0;
    st[stOffset + 5] = 1.0;
    st[stOffset + 6] = 0.0;
    st[stOffset + 7] = 1.0;
  }

  var scratchRotationMatrix = new Matrix3();
  var scratchViewMatrix = new Matrix4();
  var scratchInverseMatrix = new Matrix4();

  var scratchXDirection = new Cartesian3();
  var scratchYDirection = new Cartesian3();
  var scratchZDirection = new Cartesian3();
  var scratchNegativeX = new Cartesian3();
  var scratchNegativeY = new Cartesian3();
  var scratchNegativeZ = new Cartesian3();

  var frustumSplits = new Array(3);

  var frustumCornersNDC = new Array(4);
  frustumCornersNDC[0] = new Cartesian4(-1.0, -1.0, 1.0, 1.0);
  frustumCornersNDC[1] = new Cartesian4(1.0, -1.0, 1.0, 1.0);
  frustumCornersNDC[2] = new Cartesian4(1.0, 1.0, 1.0, 1.0);
  frustumCornersNDC[3] = new Cartesian4(-1.0, 1.0, 1.0, 1.0);

  var scratchFrustumCorners = new Array(4);
  for (var i$1 = 0; i$1 < 4; ++i$1) {
    scratchFrustumCorners[i$1] = new Cartesian4();
  }

  FrustumGeometry._computeNearFarPlanes = function (
    origin,
    orientation,
    frustumType,
    frustum,
    positions,
    xDirection,
    yDirection,
    zDirection
  ) {
    var rotationMatrix = Matrix3.fromQuaternion(
      orientation,
      scratchRotationMatrix
    );
    var x = defaultValue(xDirection, scratchXDirection);
    var y = defaultValue(yDirection, scratchYDirection);
    var z = defaultValue(zDirection, scratchZDirection);

    x = Matrix3.getColumn(rotationMatrix, 0, x);
    y = Matrix3.getColumn(rotationMatrix, 1, y);
    z = Matrix3.getColumn(rotationMatrix, 2, z);

    Cartesian3.normalize(x, x);
    Cartesian3.normalize(y, y);
    Cartesian3.normalize(z, z);

    Cartesian3.negate(x, x);

    var view = Matrix4.computeView(origin, z, y, x, scratchViewMatrix);

    var inverseView;
    var inverseViewProjection;
    if (frustumType === PERSPECTIVE) {
      var projection = frustum.projectionMatrix;
      var viewProjection = Matrix4.multiply(
        projection,
        view,
        scratchInverseMatrix
      );
      inverseViewProjection = Matrix4.inverse(
        viewProjection,
        scratchInverseMatrix
      );
    } else {
      inverseView = Matrix4.inverseTransformation(view, scratchInverseMatrix);
    }

    if (defined(inverseViewProjection)) {
      frustumSplits[0] = frustum.near;
      frustumSplits[1] = frustum.far;
    } else {
      frustumSplits[0] = 0.0;
      frustumSplits[1] = frustum.near;
      frustumSplits[2] = frustum.far;
    }

    for (var i = 0; i < 2; ++i) {
      for (var j = 0; j < 4; ++j) {
        var corner = Cartesian4.clone(
          frustumCornersNDC[j],
          scratchFrustumCorners[j]
        );

        if (!defined(inverseViewProjection)) {
          if (defined(frustum._offCenterFrustum)) {
            frustum = frustum._offCenterFrustum;
          }

          var near = frustumSplits[i];
          var far = frustumSplits[i + 1];

          corner.x =
            (corner.x * (frustum.right - frustum.left) +
              frustum.left +
              frustum.right) *
            0.5;
          corner.y =
            (corner.y * (frustum.top - frustum.bottom) +
              frustum.bottom +
              frustum.top) *
            0.5;
          corner.z = (corner.z * (near - far) - near - far) * 0.5;
          corner.w = 1.0;

          Matrix4.multiplyByVector(inverseView, corner, corner);
        } else {
          corner = Matrix4.multiplyByVector(
            inverseViewProjection,
            corner,
            corner
          );

          // Reverse perspective divide
          var w = 1.0 / corner.w;
          Cartesian3.multiplyByScalar(corner, w, corner);

          Cartesian3.subtract(corner, origin, corner);
          Cartesian3.normalize(corner, corner);

          var fac = Cartesian3.dot(z, corner);
          Cartesian3.multiplyByScalar(corner, frustumSplits[i] / fac, corner);
          Cartesian3.add(corner, origin, corner);
        }

        positions[12 * i + j * 3] = corner.x;
        positions[12 * i + j * 3 + 1] = corner.y;
        positions[12 * i + j * 3 + 2] = corner.z;
      }
    }
  };

  /**
   * Computes the geometric representation of a frustum, including its vertices, indices, and a bounding sphere.
   *
   * @param {FrustumGeometry} frustumGeometry A description of the frustum.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  FrustumGeometry.createGeometry = function (frustumGeometry) {
    var frustumType = frustumGeometry._frustumType;
    var frustum = frustumGeometry._frustum;
    var origin = frustumGeometry._origin;
    var orientation = frustumGeometry._orientation;
    var drawNearPlane = frustumGeometry._drawNearPlane;
    var vertexFormat = frustumGeometry._vertexFormat;

    var numberOfPlanes = drawNearPlane ? 6 : 5;
    var positions = new Float64Array(3 * 4 * 6);
    FrustumGeometry._computeNearFarPlanes(
      origin,
      orientation,
      frustumType,
      frustum,
      positions
    );

    // -x plane
    var offset = 3 * 4 * 2;
    positions[offset] = positions[3 * 4];
    positions[offset + 1] = positions[3 * 4 + 1];
    positions[offset + 2] = positions[3 * 4 + 2];
    positions[offset + 3] = positions[0];
    positions[offset + 4] = positions[1];
    positions[offset + 5] = positions[2];
    positions[offset + 6] = positions[3 * 3];
    positions[offset + 7] = positions[3 * 3 + 1];
    positions[offset + 8] = positions[3 * 3 + 2];
    positions[offset + 9] = positions[3 * 7];
    positions[offset + 10] = positions[3 * 7 + 1];
    positions[offset + 11] = positions[3 * 7 + 2];

    // -y plane
    offset += 3 * 4;
    positions[offset] = positions[3 * 5];
    positions[offset + 1] = positions[3 * 5 + 1];
    positions[offset + 2] = positions[3 * 5 + 2];
    positions[offset + 3] = positions[3];
    positions[offset + 4] = positions[3 + 1];
    positions[offset + 5] = positions[3 + 2];
    positions[offset + 6] = positions[0];
    positions[offset + 7] = positions[1];
    positions[offset + 8] = positions[2];
    positions[offset + 9] = positions[3 * 4];
    positions[offset + 10] = positions[3 * 4 + 1];
    positions[offset + 11] = positions[3 * 4 + 2];

    // +x plane
    offset += 3 * 4;
    positions[offset] = positions[3];
    positions[offset + 1] = positions[3 + 1];
    positions[offset + 2] = positions[3 + 2];
    positions[offset + 3] = positions[3 * 5];
    positions[offset + 4] = positions[3 * 5 + 1];
    positions[offset + 5] = positions[3 * 5 + 2];
    positions[offset + 6] = positions[3 * 6];
    positions[offset + 7] = positions[3 * 6 + 1];
    positions[offset + 8] = positions[3 * 6 + 2];
    positions[offset + 9] = positions[3 * 2];
    positions[offset + 10] = positions[3 * 2 + 1];
    positions[offset + 11] = positions[3 * 2 + 2];

    // +y plane
    offset += 3 * 4;
    positions[offset] = positions[3 * 2];
    positions[offset + 1] = positions[3 * 2 + 1];
    positions[offset + 2] = positions[3 * 2 + 2];
    positions[offset + 3] = positions[3 * 6];
    positions[offset + 4] = positions[3 * 6 + 1];
    positions[offset + 5] = positions[3 * 6 + 2];
    positions[offset + 6] = positions[3 * 7];
    positions[offset + 7] = positions[3 * 7 + 1];
    positions[offset + 8] = positions[3 * 7 + 2];
    positions[offset + 9] = positions[3 * 3];
    positions[offset + 10] = positions[3 * 3 + 1];
    positions[offset + 11] = positions[3 * 3 + 2];

    if (!drawNearPlane) {
      positions = positions.subarray(3 * 4);
    }

    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      }),
    });

    if (
      defined(vertexFormat.normal) ||
      defined(vertexFormat.tangent) ||
      defined(vertexFormat.bitangent) ||
      defined(vertexFormat.st)
    ) {
      var normals = defined(vertexFormat.normal)
        ? new Float32Array(3 * 4 * numberOfPlanes)
        : undefined;
      var tangents = defined(vertexFormat.tangent)
        ? new Float32Array(3 * 4 * numberOfPlanes)
        : undefined;
      var bitangents = defined(vertexFormat.bitangent)
        ? new Float32Array(3 * 4 * numberOfPlanes)
        : undefined;
      var st = defined(vertexFormat.st)
        ? new Float32Array(2 * 4 * numberOfPlanes)
        : undefined;

      var x = scratchXDirection;
      var y = scratchYDirection;
      var z = scratchZDirection;

      var negativeX = Cartesian3.negate(x, scratchNegativeX);
      var negativeY = Cartesian3.negate(y, scratchNegativeY);
      var negativeZ = Cartesian3.negate(z, scratchNegativeZ);

      offset = 0;
      if (drawNearPlane) {
        getAttributes(offset, normals, tangents, bitangents, st, negativeZ, x, y); // near
        offset += 3 * 4;
      }
      getAttributes(offset, normals, tangents, bitangents, st, z, negativeX, y); // far
      offset += 3 * 4;
      getAttributes(
        offset,
        normals,
        tangents,
        bitangents,
        st,
        negativeX,
        negativeZ,
        y
      ); // -x
      offset += 3 * 4;
      getAttributes(
        offset,
        normals,
        tangents,
        bitangents,
        st,
        negativeY,
        negativeZ,
        negativeX
      ); // -y
      offset += 3 * 4;
      getAttributes(offset, normals, tangents, bitangents, st, x, z, y); // +x
      offset += 3 * 4;
      getAttributes(offset, normals, tangents, bitangents, st, y, z, negativeX); // +y

      if (defined(normals)) {
        attributes.normal = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: normals,
        });
      }
      if (defined(tangents)) {
        attributes.tangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: tangents,
        });
      }
      if (defined(bitangents)) {
        attributes.bitangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: bitangents,
        });
      }
      if (defined(st)) {
        attributes.st = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 2,
          values: st,
        });
      }
    }

    var indices = new Uint16Array(6 * numberOfPlanes);
    for (var i = 0; i < numberOfPlanes; ++i) {
      var indexOffset = i * 6;
      var index = i * 4;

      indices[indexOffset] = index;
      indices[indexOffset + 1] = index + 1;
      indices[indexOffset + 2] = index + 2;
      indices[indexOffset + 3] = index;
      indices[indexOffset + 4] = index + 2;
      indices[indexOffset + 5] = index + 3;
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: BoundingSphere.fromVertices(positions),
    });
  };

  var PERSPECTIVE$1 = 0;
  var ORTHOGRAPHIC$1 = 1;

  /**
   * A description of the outline of a frustum with the given the origin and orientation.
   *
   * @alias FrustumOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {PerspectiveFrustum|OrthographicFrustum} options.frustum The frustum.
   * @param {Cartesian3} options.origin The origin of the frustum.
   * @param {Quaternion} options.orientation The orientation of the frustum.
   */
  function FrustumOutlineGeometry(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.frustum", options.frustum);
    Check.typeOf.object("options.origin", options.origin);
    Check.typeOf.object("options.orientation", options.orientation);
    //>>includeEnd('debug');

    var frustum = options.frustum;
    var orientation = options.orientation;
    var origin = options.origin;

    // This is private because it is used by DebugCameraPrimitive to draw a multi-frustum by
    // creating multiple FrustumOutlineGeometrys. This way the near plane of one frustum doesn't overlap
    // the far plane of another.
    var drawNearPlane = defaultValue(options._drawNearPlane, true);

    var frustumType;
    var frustumPackedLength;
    if (frustum instanceof PerspectiveFrustum) {
      frustumType = PERSPECTIVE$1;
      frustumPackedLength = PerspectiveFrustum.packedLength;
    } else if (frustum instanceof OrthographicFrustum) {
      frustumType = ORTHOGRAPHIC$1;
      frustumPackedLength = OrthographicFrustum.packedLength;
    }

    this._frustumType = frustumType;
    this._frustum = frustum.clone();
    this._origin = Cartesian3.clone(origin);
    this._orientation = Quaternion.clone(orientation);
    this._drawNearPlane = drawNearPlane;
    this._workerName = "createFrustumOutlineGeometry";

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      2 + frustumPackedLength + Cartesian3.packedLength + Quaternion.packedLength;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {FrustumOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  FrustumOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var frustumType = value._frustumType;
    var frustum = value._frustum;

    array[startingIndex++] = frustumType;

    if (frustumType === PERSPECTIVE$1) {
      PerspectiveFrustum.pack(frustum, array, startingIndex);
      startingIndex += PerspectiveFrustum.packedLength;
    } else {
      OrthographicFrustum.pack(frustum, array, startingIndex);
      startingIndex += OrthographicFrustum.packedLength;
    }

    Cartesian3.pack(value._origin, array, startingIndex);
    startingIndex += Cartesian3.packedLength;
    Quaternion.pack(value._orientation, array, startingIndex);
    startingIndex += Quaternion.packedLength;
    array[startingIndex] = value._drawNearPlane ? 1.0 : 0.0;

    return array;
  };

  var scratchPackPerspective$1 = new PerspectiveFrustum();
  var scratchPackOrthographic$1 = new OrthographicFrustum();
  var scratchPackQuaternion$1 = new Quaternion();
  var scratchPackorigin$1 = new Cartesian3();

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {FrustumOutlineGeometry} [result] The object into which to store the result.
   */
  FrustumOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var frustumType = array[startingIndex++];

    var frustum;
    if (frustumType === PERSPECTIVE$1) {
      frustum = PerspectiveFrustum.unpack(
        array,
        startingIndex,
        scratchPackPerspective$1
      );
      startingIndex += PerspectiveFrustum.packedLength;
    } else {
      frustum = OrthographicFrustum.unpack(
        array,
        startingIndex,
        scratchPackOrthographic$1
      );
      startingIndex += OrthographicFrustum.packedLength;
    }

    var origin = Cartesian3.unpack(array, startingIndex, scratchPackorigin$1);
    startingIndex += Cartesian3.packedLength;
    var orientation = Quaternion.unpack(
      array,
      startingIndex,
      scratchPackQuaternion$1
    );
    startingIndex += Quaternion.packedLength;
    var drawNearPlane = array[startingIndex] === 1.0;

    if (!defined(result)) {
      return new FrustumOutlineGeometry({
        frustum: frustum,
        origin: origin,
        orientation: orientation,
        _drawNearPlane: drawNearPlane,
      });
    }

    var frustumResult =
      frustumType === result._frustumType ? result._frustum : undefined;
    result._frustum = frustum.clone(frustumResult);

    result._frustumType = frustumType;
    result._origin = Cartesian3.clone(origin, result._origin);
    result._orientation = Quaternion.clone(orientation, result._orientation);
    result._drawNearPlane = drawNearPlane;

    return result;
  };

  /**
   * Computes the geometric representation of a frustum outline, including its vertices, indices, and a bounding sphere.
   *
   * @param {FrustumOutlineGeometry} frustumGeometry A description of the frustum.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  FrustumOutlineGeometry.createGeometry = function (frustumGeometry) {
    var frustumType = frustumGeometry._frustumType;
    var frustum = frustumGeometry._frustum;
    var origin = frustumGeometry._origin;
    var orientation = frustumGeometry._orientation;
    var drawNearPlane = frustumGeometry._drawNearPlane;

    var positions = new Float64Array(3 * 4 * 2);
    FrustumGeometry._computeNearFarPlanes(
      origin,
      orientation,
      frustumType,
      frustum,
      positions
    );

    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      }),
    });

    var offset;
    var index;

    var numberOfPlanes = drawNearPlane ? 2 : 1;
    var indices = new Uint16Array(8 * (numberOfPlanes + 1));

    // Build the near/far planes
    var i = drawNearPlane ? 0 : 1;
    for (; i < 2; ++i) {
      offset = drawNearPlane ? i * 8 : 0;
      index = i * 4;

      indices[offset] = index;
      indices[offset + 1] = index + 1;
      indices[offset + 2] = index + 1;
      indices[offset + 3] = index + 2;
      indices[offset + 4] = index + 2;
      indices[offset + 5] = index + 3;
      indices[offset + 6] = index + 3;
      indices[offset + 7] = index;
    }

    // Build the sides of the frustums
    for (i = 0; i < 2; ++i) {
      offset = (numberOfPlanes + i) * 8;
      index = i * 4;

      indices[offset] = index;
      indices[offset + 1] = index + 4;
      indices[offset + 2] = index + 1;
      indices[offset + 3] = index + 5;
      indices[offset + 4] = index + 2;
      indices[offset + 5] = index + 6;
      indices[offset + 6] = index + 3;
      indices[offset + 7] = index + 7;
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: BoundingSphere.fromVertices(positions),
    });
  };

  /**
   * The type of geocoding to be performed by a {@link GeocoderService}.
   * @enum {Number}
   * @see Geocoder
   */
  var GeocodeType = {
    /**
     * Perform a search where the input is considered complete.
     *
     * @type {Number}
     * @constant
     */
    SEARCH: 0,

    /**
     * Perform an auto-complete using partial input, typically
     * reserved for providing possible results as a user is typing.
     *
     * @type {Number}
     * @constant
     */
    AUTOCOMPLETE: 1,
  };
  var GeocodeType$1 = Object.freeze(GeocodeType);

  /**
   * @typedef {Object} GeocoderService.Result
   * @property {String} displayName The display name for a location
   * @property {Rectangle|Cartesian3} destination The bounding box for a location
   */

  /**
   * Provides geocoding through an external service. This type describes an interface and
   * is not intended to be used.
   * @alias GeocoderService
   * @constructor
   *
   * @see BingMapsGeocoderService
   * @see PeliasGeocoderService
   * @see OpenCageGeocoderService
   */
  function GeocoderService() {}

  /**
   * @function
   *
   * @param {String} query The query to be sent to the geocoder service
   * @param {GeocodeType} [type=GeocodeType.SEARCH] The type of geocode to perform.
   * @returns {Promise<GeocoderService.Result[]>}
   */
  GeocoderService.prototype.geocode = DeveloperError.throwInstantiationError;

  /**
   * Base class for all geometry creation utility classes that can be passed to {@link GeometryInstance}
   * for asynchronous geometry creation.
   *
   * @constructor
   * @class
   * @abstract
   */
  function GeometryFactory() {
    DeveloperError.throwInstantiationError();
  }

  /**
   * Returns a geometry.
   *
   * @param {GeometryFactory} geometryFactory A description of the circle.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  GeometryFactory.createGeometry = function (geometryFactory) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Values and type information for per-instance geometry attributes.
   *
   * @alias GeometryInstanceAttribute
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {ComponentDatatype} options.componentDatatype The datatype of each component in the attribute, e.g., individual elements in values.
   * @param {Number} options.componentsPerAttribute A number between 1 and 4 that defines the number of components in an attributes.
   * @param {Boolean} [options.normalize=false] When <code>true</code> and <code>componentDatatype</code> is an integer format, indicate that the components should be mapped to the range [0, 1] (unsigned) or [-1, 1] (signed) when they are accessed as floating-point for rendering.
   * @param {Number[]} options.value The value for the attribute.
   *
   * @exception {DeveloperError} options.componentsPerAttribute must be between 1 and 4.
   *
   *
   * @example
   * var instance = new Cesium.GeometryInstance({
   *   geometry : Cesium.BoxGeometry.fromDimensions({
   *     dimensions : new Cesium.Cartesian3(1000000.0, 1000000.0, 500000.0)
   *   }),
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(0.0, 0.0)), new Cesium.Cartesian3(0.0, 0.0, 1000000.0), new Cesium.Matrix4()),
   *   id : 'box',
   *   attributes : {
   *     color : new Cesium.GeometryInstanceAttribute({
   *       componentDatatype : Cesium.ComponentDatatype.UNSIGNED_BYTE,
   *       componentsPerAttribute : 4,
   *       normalize : true,
   *       value : [255, 255, 0, 255]
   *     })
   *   }
   * });
   *
   * @see ColorGeometryInstanceAttribute
   * @see ShowGeometryInstanceAttribute
   * @see DistanceDisplayConditionGeometryInstanceAttribute
   */
  function GeometryInstanceAttribute(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.componentDatatype)) {
      throw new DeveloperError("options.componentDatatype is required.");
    }
    if (!defined(options.componentsPerAttribute)) {
      throw new DeveloperError("options.componentsPerAttribute is required.");
    }
    if (
      options.componentsPerAttribute < 1 ||
      options.componentsPerAttribute > 4
    ) {
      throw new DeveloperError(
        "options.componentsPerAttribute must be between 1 and 4."
      );
    }
    if (!defined(options.value)) {
      throw new DeveloperError("options.value is required.");
    }
    //>>includeEnd('debug');

    /**
     * The datatype of each component in the attribute, e.g., individual elements in
     * {@link GeometryInstanceAttribute#value}.
     *
     * @type ComponentDatatype
     *
     * @default undefined
     */
    this.componentDatatype = options.componentDatatype;

    /**
     * A number between 1 and 4 that defines the number of components in an attributes.
     * For example, a position attribute with x, y, and z components would have 3 as
     * shown in the code example.
     *
     * @type Number
     *
     * @default undefined
     *
     * @example
     * show : new Cesium.GeometryInstanceAttribute({
     *   componentDatatype : Cesium.ComponentDatatype.UNSIGNED_BYTE,
     *   componentsPerAttribute : 1,
     *   normalize : true,
     *   value : [1.0]
     * })
     */
    this.componentsPerAttribute = options.componentsPerAttribute;

    /**
     * When <code>true</code> and <code>componentDatatype</code> is an integer format,
     * indicate that the components should be mapped to the range [0, 1] (unsigned)
     * or [-1, 1] (signed) when they are accessed as floating-point for rendering.
     * <p>
     * This is commonly used when storing colors using {@link ComponentDatatype.UNSIGNED_BYTE}.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     *
     * @example
     * attribute.componentDatatype = Cesium.ComponentDatatype.UNSIGNED_BYTE;
     * attribute.componentsPerAttribute = 4;
     * attribute.normalize = true;
     * attribute.value = [
     *   Cesium.Color.floatToByte(color.red),
     *   Cesium.Color.floatToByte(color.green),
     *   Cesium.Color.floatToByte(color.blue),
     *   Cesium.Color.floatToByte(color.alpha)
     * ];
     */
    this.normalize = defaultValue(options.normalize, false);

    /**
     * The values for the attributes stored in a typed array.  In the code example,
     * every three elements in <code>values</code> defines one attributes since
     * <code>componentsPerAttribute</code> is 3.
     *
     * @type {Number[]}
     *
     * @default undefined
     *
     * @example
     * show : new Cesium.GeometryInstanceAttribute({
     *   componentDatatype : Cesium.ComponentDatatype.UNSIGNED_BYTE,
     *   componentsPerAttribute : 1,
     *   normalize : true,
     *   value : [1.0]
     * })
     */
    this.value = options.value;
  }

  var tmp$1 = {};
  /*!
   * protobuf.js v6.7.0 (c) 2016, Daniel Wirtz
   * Compiled Wed, 22 Mar 2017 17:30:26 UTC
   * Licensed under the BSD-3-Clause License
   * see: https://github.com/dcodeIO/protobuf.js for details
   */
  (function(global,undefined$1){(function prelude(modules, cache, entries) {

      // This is the prelude used to bundle protobuf.js for the browser. Wraps up the CommonJS
      // sources through a conflict-free require shim and is again wrapped within an iife that
      // provides a unified `global` and a minification-friendly `undefined` var plus a global
      // "use strict" directive so that minification can remove the directives of each module.

      function $require(name) {
          var $module = cache[name];
          if (!$module)
              modules[name][0].call($module = cache[name] = { exports: {} }, $require, $module, $module.exports);
          return $module.exports;
      }

      // Expose globally
      var protobuf = global.protobuf = $require(entries[0]);

      // Commented out to avoid polluing the global scope in Node.js
      // // Be nice to AMD
      // if (typeof define === "function" && define.amd)
      //     define([], function() {
      //         protobuf.configure();
      //         return protobuf;
      //     });

      // // Be nice to CommonJS
      // if (typeof module === "object" && module && module.exports)
      //     module.exports = protobuf;

  })/* end of prelude */({1:[function(require,module,exports){
  module.exports = asPromise;

  /**
   * Returns a promise from a node-style callback function.
   * @memberof util
   * @param {function(?Error, ...*)} fn Function to call
   * @param {*} ctx Function context
   * @param {...*} params Function arguments
   * @returns {Promise<*>} Promisified function
   */
  function asPromise(fn, ctx/*, varargs */) {
      var params = [];
      for (var i = 2; i < arguments.length;)
          params.push(arguments[i++]);
      var pending = true;
      return new Promise(function asPromiseExecutor(resolve, reject) {
          params.push(function asPromiseCallback(err/*, varargs */) {
              if (pending) {
                  pending = false;
                  if (err)
                      reject(err);
                  else {
                      var args = [];
                      for (var i = 1; i < arguments.length;)
                          args.push(arguments[i++]);
                      resolve.apply(null, args);
                  }
              }
          });
          try {
              fn.apply(ctx || this, params); // eslint-disable-line no-invalid-this
          } catch (err) {
              if (pending) {
                  pending = false;
                  reject(err);
              }
          }
      });
  }

  },{}],2:[function(require,module,exports){

  /**
   * A minimal base64 implementation for number arrays.
   * @memberof util
   * @namespace
   */
  var base64 = exports;

  /**
   * Calculates the byte length of a base64 encoded string.
   * @param {string} string Base64 encoded string
   * @returns {number} Byte length
   */
  base64.length = function length(string) {
      var p = string.length;
      if (!p)
          return 0;
      var n = 0;
      while (--p % 4 > 1 && string.charAt(p) === "=")
          ++n;
      return Math.ceil(string.length * 3) / 4 - n;
  };

  // Base64 encoding table
  var b64 = new Array(64);

  // Base64 decoding table
  var s64 = new Array(123);

  // 65..90, 97..122, 48..57, 43, 47
  for (var i = 0; i < 64;)
      s64[b64[i] = i < 26 ? i + 65 : i < 52 ? i + 71 : i < 62 ? i - 4 : i - 59 | 43] = i++;

  /**
   * Encodes a buffer to a base64 encoded string.
   * @param {Uint8Array} buffer Source buffer
   * @param {number} start Source start
   * @param {number} end Source end
   * @returns {string} Base64 encoded string
   */
  base64.encode = function encode(buffer, start, end) {
      var string = []; // alt: new Array(Math.ceil((end - start) / 3) * 4);
      var i = 0, // output index
          j = 0, // goto index
          t;     // temporary
      while (start < end) {
          var b = buffer[start++];
          switch (j) {
              case 0:
                  string[i++] = b64[b >> 2];
                  t = (b & 3) << 4;
                  j = 1;
                  break;
              case 1:
                  string[i++] = b64[t | b >> 4];
                  t = (b & 15) << 2;
                  j = 2;
                  break;
              case 2:
                  string[i++] = b64[t | b >> 6];
                  string[i++] = b64[b & 63];
                  j = 0;
                  break;
          }
      }
      if (j) {
          string[i++] = b64[t];
          string[i  ] = 61;
          if (j === 1)
              string[i + 1] = 61;
      }
      return String.fromCharCode.apply(String, string);
  };

  var invalidEncoding = "invalid encoding";

  /**
   * Decodes a base64 encoded string to a buffer.
   * @param {string} string Source string
   * @param {Uint8Array} buffer Destination buffer
   * @param {number} offset Destination offset
   * @returns {number} Number of bytes written
   * @throws {Error} If encoding is invalid
   */
  base64.decode = function decode(string, buffer, offset) {
      var start = offset;
      var j = 0, // goto index
          t;     // temporary
      for (var i = 0; i < string.length;) {
          var c = string.charCodeAt(i++);
          if (c === 61 && j > 1)
              break;
          if ((c = s64[c]) === undefined$1)
              throw Error(invalidEncoding);
          switch (j) {
              case 0:
                  t = c;
                  j = 1;
                  break;
              case 1:
                  buffer[offset++] = t << 2 | (c & 48) >> 4;
                  t = c;
                  j = 2;
                  break;
              case 2:
                  buffer[offset++] = (t & 15) << 4 | (c & 60) >> 2;
                  t = c;
                  j = 3;
                  break;
              case 3:
                  buffer[offset++] = (t & 3) << 6 | c;
                  j = 0;
                  break;
          }
      }
      if (j === 1)
          throw Error(invalidEncoding);
      return offset - start;
  };

  /**
   * Tests if the specified string appears to be base64 encoded.
   * @param {string} string String to test
   * @returns {boolean} `true` if probably base64 encoded, otherwise false
   */
  base64.test = function test(string) {
      return /^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$/.test(string);
  };

  },{}],3:[function(require,module,exports){
  module.exports = EventEmitter;

  /**
   * Constructs a new event emitter instance.
   * @classdesc A minimal event emitter.
   * @memberof util
   * @constructor
   */
  function EventEmitter() {

      /**
       * Registered listeners.
       * @type {Object.<string,*>}
       * @private
       */
      this._listeners = {};
  }

  /**
   * Registers an event listener.
   * @param {string} evt Event name
   * @param {function} fn Listener
   * @param {*} [ctx] Listener context
   * @returns {util.EventEmitter} `this`
   */
  EventEmitter.prototype.on = function on(evt, fn, ctx) {
      (this._listeners[evt] || (this._listeners[evt] = [])).push({
          fn  : fn,
          ctx : ctx || this
      });
      return this;
  };

  /**
   * Removes an event listener or any matching listeners if arguments are omitted.
   * @param {string} [evt] Event name. Removes all listeners if omitted.
   * @param {function} [fn] Listener to remove. Removes all listeners of `evt` if omitted.
   * @returns {util.EventEmitter} `this`
   */
  EventEmitter.prototype.off = function off(evt, fn) {
      if (evt === undefined$1)
          this._listeners = {};
      else {
          if (fn === undefined$1)
              this._listeners[evt] = [];
          else {
              var listeners = this._listeners[evt];
              for (var i = 0; i < listeners.length;)
                  if (listeners[i].fn === fn)
                      listeners.splice(i, 1);
                  else
                      ++i;
          }
      }
      return this;
  };

  /**
   * Emits an event by calling its listeners with the specified arguments.
   * @param {string} evt Event name
   * @param {...*} args Arguments
   * @returns {util.EventEmitter} `this`
   */
  EventEmitter.prototype.emit = function emit(evt) {
      var listeners = this._listeners[evt];
      if (listeners) {
          var args = [],
              i = 1;
          for (; i < arguments.length;)
              args.push(arguments[i++]);
          for (i = 0; i < listeners.length;)
              listeners[i].fn.apply(listeners[i++].ctx, args);
      }
      return this;
  };

  },{}],4:[function(require,module,exports){
  module.exports = inquire;

  /**
   * Requires a module only if available.
   * @memberof util
   * @param {string} moduleName Module to require
   * @returns {?Object} Required module if available and not empty, otherwise `null`
   */
  function inquire(moduleName) {
      try {
          var mod = eval("quire".replace(/^/,"re"))(moduleName); // eslint-disable-line no-eval
          if (mod && (mod.length || Object.keys(mod).length))
              return mod;
      } catch (e) {} // eslint-disable-line no-empty
      return null;
  }

  },{}],5:[function(require,module,exports){
  module.exports = pool;

  /**
   * An allocator as used by {@link util.pool}.
   * @typedef PoolAllocator
   * @type {function}
   * @param {number} size Buffer size
   * @returns {Uint8Array} Buffer
   */

  /**
   * A slicer as used by {@link util.pool}.
   * @typedef PoolSlicer
   * @type {function}
   * @param {number} start Start offset
   * @param {number} end End offset
   * @returns {Uint8Array} Buffer slice
   * @this {Uint8Array}
   */

  /**
   * A general purpose buffer pool.
   * @memberof util
   * @function
   * @param {PoolAllocator} alloc Allocator
   * @param {PoolSlicer} slice Slicer
   * @param {number} [size=8192] Slab size
   * @returns {PoolAllocator} Pooled allocator
   */
  function pool(alloc, slice, size) {
      var SIZE   = size || 8192;
      var MAX    = SIZE >>> 1;
      var slab   = null;
      var offset = SIZE;
      return function pool_alloc(size) {
          if (size < 1 || size > MAX)
              return alloc(size);
          if (offset + size > SIZE) {
              slab = alloc(SIZE);
              offset = 0;
          }
          var buf = slice.call(slab, offset, offset += size);
          if (offset & 7) // align to 32 bit
              offset = (offset | 7) + 1;
          return buf;
      };
  }

  },{}],6:[function(require,module,exports){

  /**
   * A minimal UTF8 implementation for number arrays.
   * @memberof util
   * @namespace
   */
  var utf8 = exports;

  /**
   * Calculates the UTF8 byte length of a string.
   * @param {string} string String
   * @returns {number} Byte length
   */
  utf8.length = function utf8_length(string) {
      var len = 0,
          c = 0;
      for (var i = 0; i < string.length; ++i) {
          c = string.charCodeAt(i);
          if (c < 128)
              len += 1;
          else if (c < 2048)
              len += 2;
          else if ((c & 0xFC00) === 0xD800 && (string.charCodeAt(i + 1) & 0xFC00) === 0xDC00) {
              ++i;
              len += 4;
          } else
              len += 3;
      }
      return len;
  };

  /**
   * Reads UTF8 bytes as a string.
   * @param {Uint8Array} buffer Source buffer
   * @param {number} start Source start
   * @param {number} end Source end
   * @returns {string} String read
   */
  utf8.read = function utf8_read(buffer, start, end) {
      var len = end - start;
      if (len < 1)
          return "";
      var parts = null,
          chunk = [],
          i = 0, // char offset
          t;     // temporary
      while (start < end) {
          t = buffer[start++];
          if (t < 128)
              chunk[i++] = t;
          else if (t > 191 && t < 224)
              chunk[i++] = (t & 31) << 6 | buffer[start++] & 63;
          else if (t > 239 && t < 365) {
              t = ((t & 7) << 18 | (buffer[start++] & 63) << 12 | (buffer[start++] & 63) << 6 | buffer[start++] & 63) - 0x10000;
              chunk[i++] = 0xD800 + (t >> 10);
              chunk[i++] = 0xDC00 + (t & 1023);
          } else
              chunk[i++] = (t & 15) << 12 | (buffer[start++] & 63) << 6 | buffer[start++] & 63;
          if (i > 8191) {
              (parts || (parts = [])).push(String.fromCharCode.apply(String, chunk));
              i = 0;
          }
      }
      if (parts) {
          if (i)
              parts.push(String.fromCharCode.apply(String, chunk.slice(0, i)));
          return parts.join("");
      }
      return String.fromCharCode.apply(String, chunk.slice(0, i));
  };

  /**
   * Writes a string as UTF8 bytes.
   * @param {string} string Source string
   * @param {Uint8Array} buffer Destination buffer
   * @param {number} offset Destination offset
   * @returns {number} Bytes written
   */
  utf8.write = function utf8_write(string, buffer, offset) {
      var start = offset,
          c1, // character 1
          c2; // character 2
      for (var i = 0; i < string.length; ++i) {
          c1 = string.charCodeAt(i);
          if (c1 < 128) {
              buffer[offset++] = c1;
          } else if (c1 < 2048) {
              buffer[offset++] = c1 >> 6       | 192;
              buffer[offset++] = c1       & 63 | 128;
          } else if ((c1 & 0xFC00) === 0xD800 && ((c2 = string.charCodeAt(i + 1)) & 0xFC00) === 0xDC00) {
              c1 = 0x10000 + ((c1 & 0x03FF) << 10) + (c2 & 0x03FF);
              ++i;
              buffer[offset++] = c1 >> 18      | 240;
              buffer[offset++] = c1 >> 12 & 63 | 128;
              buffer[offset++] = c1 >> 6  & 63 | 128;
              buffer[offset++] = c1       & 63 | 128;
          } else {
              buffer[offset++] = c1 >> 12      | 224;
              buffer[offset++] = c1 >> 6  & 63 | 128;
              buffer[offset++] = c1       & 63 | 128;
          }
      }
      return offset - start;
  };

  },{}],7:[function(require,module,exports){
  var protobuf = exports;

  /**
   * Build type, one of `"full"`, `"light"` or `"minimal"`.
   * @name build
   * @type {string}
   * @const
   */
  protobuf.build = "minimal";

  /**
   * Named roots.
   * This is where pbjs stores generated structures (the option `-r, --root` specifies a name).
   * Can also be used manually to make roots available accross modules.
   * @name roots
   * @type {Object.<string,Root>}
   * @example
   * // pbjs -r myroot -o compiled.js ...
   *
   * // in another module:
   * require("./compiled.js");
   *
   * // in any subsequent module:
   * var root = protobuf.roots["myroot"];
   */
  protobuf.roots = {};

  // Serialization
  protobuf.Writer       = require(14);
  protobuf.BufferWriter = require(15);
  protobuf.Reader       = require(8);
  protobuf.BufferReader = require(9);

  // Utility
  protobuf.util         = require(13);
  protobuf.rpc          = require(10);
  protobuf.configure    = configure;

  /* istanbul ignore next */
  /**
   * Reconfigures the library according to the environment.
   * @returns {undefined}
   */
  function configure() {
      protobuf.Reader._configure(protobuf.BufferReader);
      protobuf.util._configure();
  }

  // Configure serialization
  protobuf.Writer._configure(protobuf.BufferWriter);
  configure();

  },{"10":10,"13":13,"14":14,"15":15,"8":8,"9":9}],8:[function(require,module,exports){
  module.exports = Reader;

  var util      = require(13);

  var BufferReader; // cyclic

  var LongBits  = util.LongBits,
      utf8      = util.utf8;

  /* istanbul ignore next */
  function indexOutOfRange(reader, writeLength) {
      return RangeError("index out of range: " + reader.pos + " + " + (writeLength || 1) + " > " + reader.len);
  }

  /**
   * Constructs a new reader instance using the specified buffer.
   * @classdesc Wire format reader using `Uint8Array` if available, otherwise `Array`.
   * @constructor
   * @param {Uint8Array} buffer Buffer to read from
   */
  function Reader(buffer) {

      /**
       * Read buffer.
       * @type {Uint8Array}
       */
      this.buf = buffer;

      /**
       * Read buffer position.
       * @type {number}
       */
      this.pos = 0;

      /**
       * Read buffer length.
       * @type {number}
       */
      this.len = buffer.length;
  }

  var create_array = typeof Uint8Array !== "undefined"
      ? function create_typed_array(buffer) {
          if (buffer instanceof Uint8Array || Array.isArray(buffer))
              return new Reader(buffer);
          throw Error("illegal buffer");
      }
      /* istanbul ignore next */
      : function create_array(buffer) {
          if (Array.isArray(buffer))
              return new Reader(buffer);
          throw Error("illegal buffer");
      };

  /**
   * Creates a new reader using the specified buffer.
   * @function
   * @param {Uint8Array|Buffer} buffer Buffer to read from
   * @returns {Reader|BufferReader} A {@link BufferReader} if `buffer` is a Buffer, otherwise a {@link Reader}
   * @throws {Error} If `buffer` is not a valid buffer
   */
  Reader.create = util.Buffer
      ? function create_buffer_setup(buffer) {
          return (Reader.create = function create_buffer(buffer) {
              return util.Buffer.isBuffer(buffer)
                  ? new BufferReader(buffer)
                  /* istanbul ignore next */
                  : create_array(buffer);
          })(buffer);
      }
      /* istanbul ignore next */
      : create_array;

  Reader.prototype._slice = util.Array.prototype.subarray || /* istanbul ignore next */ util.Array.prototype.slice;

  /**
   * Reads a varint as an unsigned 32 bit value.
   * @function
   * @returns {number} Value read
   */
  Reader.prototype.uint32 = (function read_uint32_setup() {
      var value = 4294967295; // optimizer type-hint, tends to deopt otherwise (?!)
      return function read_uint32() {
          value = (         this.buf[this.pos] & 127       ) >>> 0; if (this.buf[this.pos++] < 128) return value;
          value = (value | (this.buf[this.pos] & 127) <<  7) >>> 0; if (this.buf[this.pos++] < 128) return value;
          value = (value | (this.buf[this.pos] & 127) << 14) >>> 0; if (this.buf[this.pos++] < 128) return value;
          value = (value | (this.buf[this.pos] & 127) << 21) >>> 0; if (this.buf[this.pos++] < 128) return value;
          value = (value | (this.buf[this.pos] &  15) << 28) >>> 0; if (this.buf[this.pos++] < 128) return value;

          /* istanbul ignore next */
          if ((this.pos += 5) > this.len) {
              this.pos = this.len;
              throw indexOutOfRange(this, 10);
          }
          return value;
      };
  })();

  /**
   * Reads a varint as a signed 32 bit value.
   * @returns {number} Value read
   */
  Reader.prototype.int32 = function read_int32() {
      return this.uint32() | 0;
  };

  /**
   * Reads a zig-zag encoded varint as a signed 32 bit value.
   * @returns {number} Value read
   */
  Reader.prototype.sint32 = function read_sint32() {
      var value = this.uint32();
      return value >>> 1 ^ -(value & 1) | 0;
  };

  /* eslint-disable no-invalid-this */

  function readLongVarint() {
      // tends to deopt with local vars for octet etc.
      var bits = new LongBits(0, 0);
      var i = 0;
      if (this.len - this.pos > 4) { // fast route (lo)
          for (; i < 4; ++i) {
              // 1st..4th
              bits.lo = (bits.lo | (this.buf[this.pos] & 127) << i * 7) >>> 0;
              if (this.buf[this.pos++] < 128)
                  return bits;
          }
          // 5th
          bits.lo = (bits.lo | (this.buf[this.pos] & 127) << 28) >>> 0;
          bits.hi = (bits.hi | (this.buf[this.pos] & 127) >>  4) >>> 0;
          if (this.buf[this.pos++] < 128)
              return bits;
          i = 0;
      } else {
          for (; i < 3; ++i) {
              /* istanbul ignore next */
              if (this.pos >= this.len)
                  throw indexOutOfRange(this);
              // 1st..3th
              bits.lo = (bits.lo | (this.buf[this.pos] & 127) << i * 7) >>> 0;
              if (this.buf[this.pos++] < 128)
                  return bits;
          }
          // 4th
          bits.lo = (bits.lo | (this.buf[this.pos++] & 127) << i * 7) >>> 0;
          return bits;
      }
      if (this.len - this.pos > 4) { // fast route (hi)
          for (; i < 5; ++i) {
              // 6th..10th
              bits.hi = (bits.hi | (this.buf[this.pos] & 127) << i * 7 + 3) >>> 0;
              if (this.buf[this.pos++] < 128)
                  return bits;
          }
      } else {
          for (; i < 5; ++i) {
              /* istanbul ignore next */
              if (this.pos >= this.len)
                  throw indexOutOfRange(this);
              // 6th..10th
              bits.hi = (bits.hi | (this.buf[this.pos] & 127) << i * 7 + 3) >>> 0;
              if (this.buf[this.pos++] < 128)
                  return bits;
          }
      }
      /* istanbul ignore next */
      throw Error("invalid varint encoding");
  }

  /* eslint-enable no-invalid-this */

  /**
   * Reads a varint as a signed 64 bit value.
   * @name Reader#int64
   * @function
   * @returns {Long|number} Value read
   */

  /**
   * Reads a varint as an unsigned 64 bit value.
   * @name Reader#uint64
   * @function
   * @returns {Long|number} Value read
   */

  /**
   * Reads a zig-zag encoded varint as a signed 64 bit value.
   * @name Reader#sint64
   * @function
   * @returns {Long|number} Value read
   */

  /**
   * Reads a varint as a boolean.
   * @returns {boolean} Value read
   */
  Reader.prototype.bool = function read_bool() {
      return this.uint32() !== 0;
  };

  function readFixed32(buf, end) {
      return (buf[end - 4]
            | buf[end - 3] << 8
            | buf[end - 2] << 16
            | buf[end - 1] << 24) >>> 0;
  }

  /**
   * Reads fixed 32 bits as an unsigned 32 bit integer.
   * @returns {number} Value read
   */
  Reader.prototype.fixed32 = function read_fixed32() {

      /* istanbul ignore next */
      if (this.pos + 4 > this.len)
          throw indexOutOfRange(this, 4);

      return readFixed32(this.buf, this.pos += 4);
  };

  /**
   * Reads fixed 32 bits as a signed 32 bit integer.
   * @returns {number} Value read
   */
  Reader.prototype.sfixed32 = function read_sfixed32() {

      /* istanbul ignore next */
      if (this.pos + 4 > this.len)
          throw indexOutOfRange(this, 4);

      return readFixed32(this.buf, this.pos += 4) | 0;
  };

  /* eslint-disable no-invalid-this */

  function readFixed64(/* this: Reader */) {

      /* istanbul ignore next */
      if (this.pos + 8 > this.len)
          throw indexOutOfRange(this, 8);

      return new LongBits(readFixed32(this.buf, this.pos += 4), readFixed32(this.buf, this.pos += 4));
  }

  /* eslint-enable no-invalid-this */

  /**
   * Reads fixed 64 bits.
   * @name Reader#fixed64
   * @function
   * @returns {Long|number} Value read
   */

  /**
   * Reads zig-zag encoded fixed 64 bits.
   * @name Reader#sfixed64
   * @function
   * @returns {Long|number} Value read
   */

  var readFloat = typeof Float32Array !== "undefined"
      ? (function() {
          var f32 = new Float32Array(1),
              f8b = new Uint8Array(f32.buffer);
          f32[0] = -0;
          return f8b[3] // already le?
              ? function readFloat_f32(buf, pos) {
                  f8b[0] = buf[pos    ];
                  f8b[1] = buf[pos + 1];
                  f8b[2] = buf[pos + 2];
                  f8b[3] = buf[pos + 3];
                  return f32[0];
              }
              /* istanbul ignore next */
              : function readFloat_f32_le(buf, pos) {
                  f8b[0] = buf[pos + 3];
                  f8b[1] = buf[pos + 2];
                  f8b[2] = buf[pos + 1];
                  f8b[3] = buf[pos    ];
                  return f32[0];
              };
      })()
      /* istanbul ignore next */
      : function readFloat_ieee754(buf, pos) {
          var uint = readFixed32(buf, pos + 4),
              sign = (uint >> 31) * 2 + 1,
              exponent = uint >>> 23 & 255,
              mantissa = uint & 8388607;
          return exponent === 255
              ? mantissa
                ? NaN
                : sign * Infinity
              : exponent === 0 // denormal
                ? sign * 1.401298464324817e-45 * mantissa
                : sign * Math.pow(2, exponent - 150) * (mantissa + 8388608);
      };

  /**
   * Reads a float (32 bit) as a number.
   * @function
   * @returns {number} Value read
   */
  Reader.prototype.float = function read_float() {

      /* istanbul ignore next */
      if (this.pos + 4 > this.len)
          throw indexOutOfRange(this, 4);

      var value = readFloat(this.buf, this.pos);
      this.pos += 4;
      return value;
  };

  var readDouble = typeof Float64Array !== "undefined"
      ? (function() {
          var f64 = new Float64Array(1),
              f8b = new Uint8Array(f64.buffer);
          f64[0] = -0;
          return f8b[7] // already le?
              ? function readDouble_f64(buf, pos) {
                  f8b[0] = buf[pos    ];
                  f8b[1] = buf[pos + 1];
                  f8b[2] = buf[pos + 2];
                  f8b[3] = buf[pos + 3];
                  f8b[4] = buf[pos + 4];
                  f8b[5] = buf[pos + 5];
                  f8b[6] = buf[pos + 6];
                  f8b[7] = buf[pos + 7];
                  return f64[0];
              }
              /* istanbul ignore next */
              : function readDouble_f64_le(buf, pos) {
                  f8b[0] = buf[pos + 7];
                  f8b[1] = buf[pos + 6];
                  f8b[2] = buf[pos + 5];
                  f8b[3] = buf[pos + 4];
                  f8b[4] = buf[pos + 3];
                  f8b[5] = buf[pos + 2];
                  f8b[6] = buf[pos + 1];
                  f8b[7] = buf[pos    ];
                  return f64[0];
              };
      })()
      /* istanbul ignore next */
      : function readDouble_ieee754(buf, pos) {
          var lo = readFixed32(buf, pos + 4),
              hi = readFixed32(buf, pos + 8);
          var sign = (hi >> 31) * 2 + 1,
              exponent = hi >>> 20 & 2047,
              mantissa = 4294967296 * (hi & 1048575) + lo;
          return exponent === 2047
              ? mantissa
                ? NaN
                : sign * Infinity
              : exponent === 0 // denormal
                ? sign * 5e-324 * mantissa
                : sign * Math.pow(2, exponent - 1075) * (mantissa + 4503599627370496);
      };

  /**
   * Reads a double (64 bit float) as a number.
   * @function
   * @returns {number} Value read
   */
  Reader.prototype.double = function read_double() {

      /* istanbul ignore next */
      if (this.pos + 8 > this.len)
          throw indexOutOfRange(this, 4);

      var value = readDouble(this.buf, this.pos);
      this.pos += 8;
      return value;
  };

  /**
   * Reads a sequence of bytes preceeded by its length as a varint.
   * @returns {Uint8Array} Value read
   */
  Reader.prototype.bytes = function read_bytes() {
      var length = this.uint32(),
          start  = this.pos,
          end    = this.pos + length;

      /* istanbul ignore next */
      if (end > this.len)
          throw indexOutOfRange(this, length);

      this.pos += length;
      return start === end // fix for IE 10/Win8 and others' subarray returning array of size 1
          ? new this.buf.constructor(0)
          : this._slice.call(this.buf, start, end);
  };

  /**
   * Reads a string preceeded by its byte length as a varint.
   * @returns {string} Value read
   */
  Reader.prototype.string = function read_string() {
      var bytes = this.bytes();
      return utf8.read(bytes, 0, bytes.length);
  };

  /**
   * Skips the specified number of bytes if specified, otherwise skips a varint.
   * @param {number} [length] Length if known, otherwise a varint is assumed
   * @returns {Reader} `this`
   */
  Reader.prototype.skip = function skip(length) {
      if (typeof length === "number") {
          /* istanbul ignore next */
          if (this.pos + length > this.len)
              throw indexOutOfRange(this, length);
          this.pos += length;
      } else {
          /* istanbul ignore next */
          do {
              if (this.pos >= this.len)
                  throw indexOutOfRange(this);
          } while (this.buf[this.pos++] & 128);
      }
      return this;
  };

  /**
   * Skips the next element of the specified wire type.
   * @param {number} wireType Wire type received
   * @returns {Reader} `this`
   */
  Reader.prototype.skipType = function(wireType) {
      switch (wireType) {
          case 0:
              this.skip();
              break;
          case 1:
              this.skip(8);
              break;
          case 2:
              this.skip(this.uint32());
              break;
          case 3:
              do { // eslint-disable-line no-constant-condition
                  if ((wireType = this.uint32() & 7) === 4)
                      break;
                  this.skipType(wireType);
              } while (true);
              break;
          case 5:
              this.skip(4);
              break;

          /* istanbul ignore next */
          default:
              throw Error("invalid wire type " + wireType + " at offset " + this.pos);
      }
      return this;
  };

  Reader._configure = function(BufferReader_) {
      BufferReader = BufferReader_;

      var fn = util.Long ? "toLong" : /* istanbul ignore next */ "toNumber";
      util.merge(Reader.prototype, {

          int64: function read_int64() {
              return readLongVarint.call(this)[fn](false);
          },

          uint64: function read_uint64() {
              return readLongVarint.call(this)[fn](true);
          },

          sint64: function read_sint64() {
              return readLongVarint.call(this).zzDecode()[fn](false);
          },

          fixed64: function read_fixed64() {
              return readFixed64.call(this)[fn](true);
          },

          sfixed64: function read_sfixed64() {
              return readFixed64.call(this)[fn](false);
          }

      });
  };

  },{"13":13}],9:[function(require,module,exports){
  module.exports = BufferReader;

  // extends Reader
  var Reader = require(8);
  (BufferReader.prototype = Object.create(Reader.prototype)).constructor = BufferReader;

  var util = require(13);

  /**
   * Constructs a new buffer reader instance.
   * @classdesc Wire format reader using node buffers.
   * @extends Reader
   * @constructor
   * @param {Buffer} buffer Buffer to read from
   */
  function BufferReader(buffer) {
      Reader.call(this, buffer);

      /**
       * Read buffer.
       * @name BufferReader#buf
       * @type {Buffer}
       */
  }

  /* istanbul ignore else */
  if (util.Buffer)
      BufferReader.prototype._slice = util.Buffer.prototype.slice;

  /**
   * @override
   */
  BufferReader.prototype.string = function read_string_buffer() {
      var len = this.uint32(); // modifies pos
      return this.buf.utf8Slice(this.pos, this.pos = Math.min(this.pos + len, this.len));
  };

  /**
   * Reads a sequence of bytes preceeded by its length as a varint.
   * @name BufferReader#bytes
   * @function
   * @returns {Buffer} Value read
   */

  },{"13":13,"8":8}],10:[function(require,module,exports){

  /**
   * Streaming RPC helpers.
   * @namespace
   */
  var rpc = exports;

  /**
   * RPC implementation passed to {@link Service#create} performing a service request on network level, i.e. by utilizing http requests or websockets.
   * @typedef RPCImpl
   * @type {function}
   * @param {Method|rpc.ServiceMethod} method Reflected or static method being called
   * @param {Uint8Array} requestData Request data
   * @param {RPCImplCallback} callback Callback function
   * @returns {undefined}
   * @example
   * function rpcImpl(method, requestData, callback) {
   *     if (protobuf.util.lcFirst(method.name) !== "myMethod") // compatible with static code
   *         throw Error("no such method");
   *     asynchronouslyObtainAResponse(requestData, function(err, responseData) {
   *         callback(err, responseData);
   *     });
   * }
   */

  /**
   * Node-style callback as used by {@link RPCImpl}.
   * @typedef RPCImplCallback
   * @type {function}
   * @param {?Error} error Error, if any, otherwise `null`
   * @param {?Uint8Array} [response] Response data or `null` to signal end of stream, if there hasn't been an error
   * @returns {undefined}
   */

  rpc.Service = require(11);

  },{"11":11}],11:[function(require,module,exports){
  module.exports = Service;

  var util = require(13);

  // Extends EventEmitter
  (Service.prototype = Object.create(util.EventEmitter.prototype)).constructor = Service;

  /**
   * A service method callback as used by {@link rpc.ServiceMethod|ServiceMethod}.
   *
   * Differs from {@link RPCImplCallback} in that it is an actual callback of a service method which may not return `response = null`.
   * @typedef rpc.ServiceMethodCallback
   * @type {function}
   * @param {?Error} error Error, if any
   * @param {?Message} [response] Response message
   * @returns {undefined}
   */

  /**
   * A service method part of a {@link rpc.ServiceMethodMixin|ServiceMethodMixin} and thus {@link rpc.Service} as created by {@link Service.create}.
   * @typedef rpc.ServiceMethod
   * @type {function}
   * @param {Message|Object.<string,*>} request Request message or plain object
   * @param {rpc.ServiceMethodCallback} [callback] Node-style callback called with the error, if any, and the response message
   * @returns {Promise<Message>} Promise if `callback` has been omitted, otherwise `undefined`
   */

  /**
   * A service method mixin.
   *
   * When using TypeScript, mixed in service methods are only supported directly with a type definition of a static module (used with reflection). Otherwise, explicit casting is required.
   * @typedef rpc.ServiceMethodMixin
   * @type {Object.<string,rpc.ServiceMethod>}
   * @example
   * // Explicit casting with TypeScript
   * (myRpcService["myMethod"] as protobuf.rpc.ServiceMethod)(...)
   */

  /**
   * Constructs a new RPC service instance.
   * @classdesc An RPC service as returned by {@link Service#create}.
   * @exports rpc.Service
   * @extends util.EventEmitter
   * @augments rpc.ServiceMethodMixin
   * @constructor
   * @param {RPCImpl} rpcImpl RPC implementation
   * @param {boolean} [requestDelimited=false] Whether requests are length-delimited
   * @param {boolean} [responseDelimited=false] Whether responses are length-delimited
   */
  function Service(rpcImpl, requestDelimited, responseDelimited) {

      if (typeof rpcImpl !== "function")
          throw TypeError("rpcImpl must be a function");

      util.EventEmitter.call(this);

      /**
       * RPC implementation. Becomes `null` once the service is ended.
       * @type {?RPCImpl}
       */
      this.rpcImpl = rpcImpl;

      /**
       * Whether requests are length-delimited.
       * @type {boolean}
       */
      this.requestDelimited = Boolean(requestDelimited);

      /**
       * Whether responses are length-delimited.
       * @type {boolean}
       */
      this.responseDelimited = Boolean(responseDelimited);
  }

  /**
   * Calls a service method through {@link rpc.Service#rpcImpl|rpcImpl}.
   * @param {Method|rpc.ServiceMethod} method Reflected or static method
   * @param {function} requestCtor Request constructor
   * @param {function} responseCtor Response constructor
   * @param {Message|Object.<string,*>} request Request message or plain object
   * @param {rpc.ServiceMethodCallback} callback Service callback
   * @returns {undefined}
   */
  Service.prototype.rpcCall = function rpcCall(method, requestCtor, responseCtor, request, callback) {

      if (!request)
          throw TypeError("request must be specified");

      var self = this;
      if (!callback)
          return util.asPromise(rpcCall, self, method, requestCtor, responseCtor, request);

      if (!self.rpcImpl) {
          setTimeout(function() { callback(Error("already ended")); }, 0);
          return undefined$1;
      }

      try {
          return self.rpcImpl(
              method,
              requestCtor[self.requestDelimited ? "encodeDelimited" : "encode"](request).finish(),
              function rpcCallback(err, response) {

                  if (err) {
                      self.emit("error", err, method);
                      return callback(err);
                  }

                  if (response === null) {
                      self.end(/* endedByRPC */ true);
                      return undefined$1;
                  }

                  if (!(response instanceof responseCtor)) {
                      try {
                          response = responseCtor[self.responseDelimited ? "decodeDelimited" : "decode"](response);
                      } catch (err) {
                          self.emit("error", err, method);
                          return callback(err);
                      }
                  }

                  self.emit("data", response, method);
                  return callback(null, response);
              }
          );
      } catch (err) {
          self.emit("error", err, method);
          setTimeout(function() { callback(err); }, 0);
          return undefined$1;
      }
  };

  /**
   * Ends this service and emits the `end` event.
   * @param {boolean} [endedByRPC=false] Whether the service has been ended by the RPC implementation.
   * @returns {rpc.Service} `this`
   */
  Service.prototype.end = function end(endedByRPC) {
      if (this.rpcImpl) {
          if (!endedByRPC) // signal end to rpcImpl
              this.rpcImpl(null, null, null);
          this.rpcImpl = null;
          this.emit("end").off();
      }
      return this;
  };

  },{"13":13}],12:[function(require,module,exports){
  module.exports = LongBits;

  var util = require(13);

  /**
   * Any compatible Long instance.
   *
   * This is a minimal stand-alone definition of a Long instance. The actual type is that exported by long.js.
   * @typedef Long
   * @type {Object}
   * @property {number} low Low bits
   * @property {number} high High bits
   * @property {boolean} unsigned Whether unsigned or not
   */

  /**
   * Constructs new long bits.
   * @classdesc Helper class for working with the low and high bits of a 64 bit value.
   * @memberof util
   * @constructor
   * @param {number} lo Low 32 bits, unsigned
   * @param {number} hi High 32 bits, unsigned
   */
  function LongBits(lo, hi) {

      // note that the casts below are theoretically unnecessary as of today, but older statically
      // generated converter code might still call the ctor with signed 32bits. kept for compat.

      /**
       * Low bits.
       * @type {number}
       */
      this.lo = lo >>> 0;

      /**
       * High bits.
       * @type {number}
       */
      this.hi = hi >>> 0;
  }

  /**
   * Zero bits.
   * @memberof util.LongBits
   * @type {util.LongBits}
   */
  var zero = LongBits.zero = new LongBits(0, 0);

  zero.toNumber = function() { return 0; };
  zero.zzEncode = zero.zzDecode = function() { return this; };
  zero.length = function() { return 1; };

  /**
   * Zero hash.
   * @memberof util.LongBits
   * @type {string}
   */
  var zeroHash = LongBits.zeroHash = "\0\0\0\0\0\0\0\0";

  /**
   * Constructs new long bits from the specified number.
   * @param {number} value Value
   * @returns {util.LongBits} Instance
   */
  LongBits.fromNumber = function fromNumber(value) {
      if (value === 0)
          return zero;
      var sign = value < 0;
      if (sign)
          value = -value;
      var lo = value >>> 0,
          hi = (value - lo) / 4294967296 >>> 0;
      if (sign) {
          hi = ~hi >>> 0;
          lo = ~lo >>> 0;
          if (++lo > 4294967295) {
              lo = 0;
              if (++hi > 4294967295)
                  hi = 0;
          }
      }
      return new LongBits(lo, hi);
  };

  /**
   * Constructs new long bits from a number, long or string.
   * @param {Long|number|string} value Value
   * @returns {util.LongBits} Instance
   */
  LongBits.from = function from(value) {
      if (typeof value === "number")
          return LongBits.fromNumber(value);
      if (util.isString(value)) {
          /* istanbul ignore else */
          if (util.Long)
              value = util.Long.fromString(value);
          else
              return LongBits.fromNumber(parseInt(value, 10));
      }
      return value.low || value.high ? new LongBits(value.low >>> 0, value.high >>> 0) : zero;
  };

  /**
   * Converts this long bits to a possibly unsafe JavaScript number.
   * @param {boolean} [unsigned=false] Whether unsigned or not
   * @returns {number} Possibly unsafe number
   */
  LongBits.prototype.toNumber = function toNumber(unsigned) {
      if (!unsigned && this.hi >>> 31) {
          var lo = ~this.lo + 1 >>> 0,
              hi = ~this.hi     >>> 0;
          if (!lo)
              hi = hi + 1 >>> 0;
          return -(lo + hi * 4294967296);
      }
      return this.lo + this.hi * 4294967296;
  };

  /**
   * Converts this long bits to a long.
   * @param {boolean} [unsigned=false] Whether unsigned or not
   * @returns {Long} Long
   */
  LongBits.prototype.toLong = function toLong(unsigned) {
      return util.Long
          ? new util.Long(this.lo | 0, this.hi | 0, Boolean(unsigned))
          /* istanbul ignore next */
          : { low: this.lo | 0, high: this.hi | 0, unsigned: Boolean(unsigned) };
  };

  var charCodeAt = String.prototype.charCodeAt;

  /**
   * Constructs new long bits from the specified 8 characters long hash.
   * @param {string} hash Hash
   * @returns {util.LongBits} Bits
   */
  LongBits.fromHash = function fromHash(hash) {
      if (hash === zeroHash)
          return zero;
      return new LongBits(
          ( charCodeAt.call(hash, 0)
          | charCodeAt.call(hash, 1) << 8
          | charCodeAt.call(hash, 2) << 16
          | charCodeAt.call(hash, 3) << 24) >>> 0
      ,
          ( charCodeAt.call(hash, 4)
          | charCodeAt.call(hash, 5) << 8
          | charCodeAt.call(hash, 6) << 16
          | charCodeAt.call(hash, 7) << 24) >>> 0
      );
  };

  /**
   * Converts this long bits to a 8 characters long hash.
   * @returns {string} Hash
   */
  LongBits.prototype.toHash = function toHash() {
      return String.fromCharCode(
          this.lo        & 255,
          this.lo >>> 8  & 255,
          this.lo >>> 16 & 255,
          this.lo >>> 24      ,
          this.hi        & 255,
          this.hi >>> 8  & 255,
          this.hi >>> 16 & 255,
          this.hi >>> 24
      );
  };

  /**
   * Zig-zag encodes this long bits.
   * @returns {util.LongBits} `this`
   */
  LongBits.prototype.zzEncode = function zzEncode() {
      var mask =   this.hi >> 31;
      this.hi  = ((this.hi << 1 | this.lo >>> 31) ^ mask) >>> 0;
      this.lo  = ( this.lo << 1                   ^ mask) >>> 0;
      return this;
  };

  /**
   * Zig-zag decodes this long bits.
   * @returns {util.LongBits} `this`
   */
  LongBits.prototype.zzDecode = function zzDecode() {
      var mask = -(this.lo & 1);
      this.lo  = ((this.lo >>> 1 | this.hi << 31) ^ mask) >>> 0;
      this.hi  = ( this.hi >>> 1                  ^ mask) >>> 0;
      return this;
  };

  /**
   * Calculates the length of this longbits when encoded as a varint.
   * @returns {number} Length
   */
  LongBits.prototype.length = function length() {
      var part0 =  this.lo,
          part1 = (this.lo >>> 28 | this.hi << 4) >>> 0,
          part2 =  this.hi >>> 24;
      return part2 === 0
           ? part1 === 0
             ? part0 < 16384
               ? part0 < 128 ? 1 : 2
               : part0 < 2097152 ? 3 : 4
             : part1 < 16384
               ? part1 < 128 ? 5 : 6
               : part1 < 2097152 ? 7 : 8
           : part2 < 128 ? 9 : 10;
  };

  },{"13":13}],13:[function(require,module,exports){
  var util = exports;

  // used to return a Promise where callback is omitted
  util.asPromise = require(1);

  // converts to / from base64 encoded strings
  util.base64 = require(2);

  // base class of rpc.Service
  util.EventEmitter = require(3);

  // requires modules optionally and hides the call from bundlers
  util.inquire = require(4);

  // converts to / from utf8 encoded strings
  util.utf8 = require(6);

  // provides a node-like buffer pool in the browser
  util.pool = require(5);

  // utility to work with the low and high bits of a 64 bit value
  util.LongBits = require(12);

  /**
   * An immuable empty array.
   * @memberof util
   * @type {Array.<*>}
   */
  util.emptyArray = Object.freeze ? Object.freeze([]) : /* istanbul ignore next */ []; // used on prototypes

  /**
   * An immutable empty object.
   * @type {Object}
   */
  util.emptyObject = Object.freeze ? Object.freeze({}) : /* istanbul ignore next */ {}; // used on prototypes

  /**
   * Whether running within node or not.
   * @memberof util
   * @type {boolean}
   */
  util.isNode = Boolean(global.process && global.process.versions && global.process.versions.node);

  /**
   * Tests if the specified value is an integer.
   * @function
   * @param {*} value Value to test
   * @returns {boolean} `true` if the value is an integer
   */
  util.isInteger = Number.isInteger || /* istanbul ignore next */ function isInteger(value) {
      return typeof value === "number" && isFinite(value) && Math.floor(value) === value;
  };

  /**
   * Tests if the specified value is a string.
   * @param {*} value Value to test
   * @returns {boolean} `true` if the value is a string
   */
  util.isString = function isString(value) {
      return typeof value === "string" || value instanceof String;
  };

  /**
   * Tests if the specified value is a non-null object.
   * @param {*} value Value to test
   * @returns {boolean} `true` if the value is a non-null object
   */
  util.isObject = function isObject(value) {
      return value && typeof value === "object";
  };

  /**
   * Node's Buffer class if available.
   * @type {?function(new: Buffer)}
   */
  util.Buffer = (function() {
      try {
          var Buffer = util.inquire("buffer").Buffer;
          // refuse to use non-node buffers if not explicitly assigned (perf reasons):
          return Buffer.prototype.utf8Write ? Buffer : /* istanbul ignore next */ null;
      } catch (e) {
          /* istanbul ignore next */
          return null;
      }
  })();

  /**
   * Internal alias of or polyfull for Buffer.from.
   * @type {?function}
   * @param {string|number[]} value Value
   * @param {string} [encoding] Encoding if value is a string
   * @returns {Uint8Array}
   * @private
   */
  util._Buffer_from = null;

  /**
   * Internal alias of or polyfill for Buffer.allocUnsafe.
   * @type {?function}
   * @param {number} size Buffer size
   * @returns {Uint8Array}
   * @private
   */
  util._Buffer_allocUnsafe = null;

  /**
   * Creates a new buffer of whatever type supported by the environment.
   * @param {number|number[]} [sizeOrArray=0] Buffer size or number array
   * @returns {Uint8Array|Buffer} Buffer
   */
  util.newBuffer = function newBuffer(sizeOrArray) {
      /* istanbul ignore next */
      return typeof sizeOrArray === "number"
          ? util.Buffer
              ? util._Buffer_allocUnsafe(sizeOrArray)
              : new util.Array(sizeOrArray)
          : util.Buffer
              ? util._Buffer_from(sizeOrArray)
              : typeof Uint8Array === "undefined"
                  ? sizeOrArray
                  : new Uint8Array(sizeOrArray);
  };

  /**
   * Array implementation used in the browser. `Uint8Array` if supported, otherwise `Array`.
   * @type {?function(new: Uint8Array, *)}
   */
  util.Array = typeof Uint8Array !== "undefined" ? Uint8Array /* istanbul ignore next */ : Array;

  /**
   * Long.js's Long class if available.
   * @type {?function(new: Long)}
   */
  util.Long = /* istanbul ignore next */ global.dcodeIO && /* istanbul ignore next */ global.dcodeIO.Long || util.inquire("long");

  /**
   * Regular expression used to verify 2 bit (`bool`) map keys.
   * @type {RegExp}
   */
  util.key2Re = /^true|false|0|1$/;

  /**
   * Regular expression used to verify 32 bit (`int32` etc.) map keys.
   * @type {RegExp}
   */
  util.key32Re = /^-?(?:0|[1-9][0-9]*)$/;

  /**
   * Regular expression used to verify 64 bit (`int64` etc.) map keys.
   * @type {RegExp}
   */
  util.key64Re = /^(?:[\\x00-\\xff]{8}|-?(?:0|[1-9][0-9]*))$/;

  /**
   * Converts a number or long to an 8 characters long hash string.
   * @param {Long|number} value Value to convert
   * @returns {string} Hash
   */
  util.longToHash = function longToHash(value) {
      return value
          ? util.LongBits.from(value).toHash()
          : util.LongBits.zeroHash;
  };

  /**
   * Converts an 8 characters long hash string to a long or number.
   * @param {string} hash Hash
   * @param {boolean} [unsigned=false] Whether unsigned or not
   * @returns {Long|number} Original value
   */
  util.longFromHash = function longFromHash(hash, unsigned) {
      var bits = util.LongBits.fromHash(hash);
      if (util.Long)
          return util.Long.fromBits(bits.lo, bits.hi, unsigned);
      return bits.toNumber(Boolean(unsigned));
  };

  /**
   * Merges the properties of the source object into the destination object.
   * @memberof util
   * @param {Object.<string,*>} dst Destination object
   * @param {Object.<string,*>} src Source object
   * @param {boolean} [ifNotSet=false] Merges only if the key is not already set
   * @returns {Object.<string,*>} Destination object
   */
  function merge(dst, src, ifNotSet) { // used by converters
      for (var keys = Object.keys(src), i = 0; i < keys.length; ++i)
          if (dst[keys[i]] === undefined$1 || !ifNotSet)
              dst[keys[i]] = src[keys[i]];
      return dst;
  }

  util.merge = merge;

  /**
   * Converts the first character of a string to lower case.
   * @param {string} str String to convert
   * @returns {string} Converted string
   */
  util.lcFirst = function lcFirst(str) {
      return str.charAt(0).toLowerCase() + str.substring(1);
  };

  /**
   * Creates a custom error constructor.
   * @memberof util
   * @param {string} name Error name
   * @returns {function} Custom error constructor
   */
  function newError(name) {

      function CustomError(message, properties) {

          if (!(this instanceof CustomError))
              return new CustomError(message, properties);

          // Error.call(this, message);
          // ^ just returns a new error instance because the ctor can be called as a function

          Object.defineProperty(this, "message", { get: function() { return message; } });

          /* istanbul ignore next */
          if (Error.captureStackTrace) // node
              Error.captureStackTrace(this, CustomError);
          else
              Object.defineProperty(this, "stack", { value: (new Error()).stack || "" });

          if (properties)
              merge(this, properties);
      }

      (CustomError.prototype = Object.create(Error.prototype)).constructor = CustomError;

      Object.defineProperty(CustomError.prototype, "name", { get: function() { return name; } });

      CustomError.prototype.toString = function toString() {
          return this.name + ": " + this.message;
      };

      return CustomError;
  }

  util.newError = newError;

  /**
   * Constructs a new protocol error.
   * @classdesc Error subclass indicating a protocol specifc error.
   * @memberof util
   * @extends Error
   * @constructor
   * @param {string} message Error message
   * @param {Object.<string,*>=} properties Additional properties
   * @example
   * try {
   *     MyMessage.decode(someBuffer); // throws if required fields are missing
   * } catch (e) {
   *     if (e instanceof ProtocolError && e.instance)
   *         console.log("decoded so far: " + JSON.stringify(e.instance));
   * }
   */
  util.ProtocolError = newError("ProtocolError");

  /**
   * So far decoded message instance.
   * @name util.ProtocolError#instance
   * @type {Message}
   */

  /**
   * Builds a getter for a oneof's present field name.
   * @param {string[]} fieldNames Field names
   * @returns {function():string|undefined} Unbound getter
   */
  util.oneOfGetter = function getOneOf(fieldNames) {
      var fieldMap = {};
      for (var i = 0; i < fieldNames.length; ++i)
          fieldMap[fieldNames[i]] = 1;

      /**
       * @returns {string|undefined} Set field name, if any
       * @this Object
       * @ignore
       */
      return function() { // eslint-disable-line consistent-return
          for (var keys = Object.keys(this), i = keys.length - 1; i > -1; --i)
              if (fieldMap[keys[i]] === 1 && this[keys[i]] !== undefined$1 && this[keys[i]] !== null)
                  return keys[i];
      };
  };

  /**
   * Builds a setter for a oneof's present field name.
   * @param {string[]} fieldNames Field names
   * @returns {function(?string):undefined} Unbound setter
   */
  util.oneOfSetter = function setOneOf(fieldNames) {

      /**
       * @param {string} name Field name
       * @returns {undefined}
       * @this Object
       * @ignore
       */
      return function(name) {
          for (var i = 0; i < fieldNames.length; ++i)
              if (fieldNames[i] !== name)
                  delete this[fieldNames[i]];
      };
  };

  /**
   * Lazily resolves fully qualified type names against the specified root.
   * @param {Root} root Root instanceof
   * @param {Object.<number,string|ReflectionObject>} lazyTypes Type names
   * @returns {undefined}
   */
  util.lazyResolve = function lazyResolve(root, lazyTypes) {
      for (var i = 0; i < lazyTypes.length; ++i) {
          for (var keys = Object.keys(lazyTypes[i]), j = 0; j < keys.length; ++j) {
              var path = lazyTypes[i][keys[j]].split("."),
                  ptr  = root;
              while (path.length)
                  ptr = ptr[path.shift()];
              lazyTypes[i][keys[j]] = ptr;
          }
      }
  };

  /**
   * Default conversion options used for {@link Message#toJSON} implementations. Longs, enums and bytes are converted to strings by default.
   * @type {ConversionOptions}
   */
  util.toJSONOptions = {
      longs: String,
      enums: String,
      bytes: String
  };

  util._configure = function() {
      var Buffer = util.Buffer;
      /* istanbul ignore if */
      if (!Buffer) {
          util._Buffer_from = util._Buffer_allocUnsafe = null;
          return;
      }
      // because node 4.x buffers are incompatible & immutable
      // see: https://github.com/dcodeIO/protobuf.js/pull/665
      util._Buffer_from = Buffer.from !== Uint8Array.from && Buffer.from ||
          /* istanbul ignore next */
          function Buffer_from(value, encoding) {
              return new Buffer(value, encoding);
          };
      util._Buffer_allocUnsafe = Buffer.allocUnsafe ||
          /* istanbul ignore next */
          function Buffer_allocUnsafe(size) {
              return new Buffer(size);
          };
  };

  },{"1":1,"12":12,"2":2,"3":3,"4":4,"5":5,"6":6}],14:[function(require,module,exports){
  module.exports = Writer;

  var util      = require(13);

  var BufferWriter; // cyclic

  var LongBits  = util.LongBits,
      base64    = util.base64,
      utf8      = util.utf8;

  /**
   * Constructs a new writer operation instance.
   * @classdesc Scheduled writer operation.
   * @constructor
   * @param {function(*, Uint8Array, number)} fn Function to call
   * @param {number} len Value byte length
   * @param {*} val Value to write
   * @ignore
   */
  function Op(fn, len, val) {

      /**
       * Function to call.
       * @type {function(Uint8Array, number, *)}
       */
      this.fn = fn;

      /**
       * Value byte length.
       * @type {number}
       */
      this.len = len;

      /**
       * Next operation.
       * @type {Writer.Op|undefined}
       */
      this.next = undefined$1;

      /**
       * Value to write.
       * @type {*}
       */
      this.val = val; // type varies
  }

  /* istanbul ignore next */
  function noop() {} // eslint-disable-line no-empty-function

  /**
   * Constructs a new writer state instance.
   * @classdesc Copied writer state.
   * @memberof Writer
   * @constructor
   * @param {Writer} writer Writer to copy state from
   * @private
   * @ignore
   */
  function State(writer) {

      /**
       * Current head.
       * @type {Writer.Op}
       */
      this.head = writer.head;

      /**
       * Current tail.
       * @type {Writer.Op}
       */
      this.tail = writer.tail;

      /**
       * Current buffer length.
       * @type {number}
       */
      this.len = writer.len;

      /**
       * Next state.
       * @type {?State}
       */
      this.next = writer.states;
  }

  /**
   * Constructs a new writer instance.
   * @classdesc Wire format writer using `Uint8Array` if available, otherwise `Array`.
   * @constructor
   */
  function Writer() {

      /**
       * Current length.
       * @type {number}
       */
      this.len = 0;

      /**
       * Operations head.
       * @type {Object}
       */
      this.head = new Op(noop, 0, 0);

      /**
       * Operations tail
       * @type {Object}
       */
      this.tail = this.head;

      /**
       * Linked forked states.
       * @type {?Object}
       */
      this.states = null;

      // When a value is written, the writer calculates its byte length and puts it into a linked
      // list of operations to perform when finish() is called. This both allows us to allocate
      // buffers of the exact required size and reduces the amount of work we have to do compared
      // to first calculating over objects and then encoding over objects. In our case, the encoding
      // part is just a linked list walk calling operations with already prepared values.
  }

  /**
   * Creates a new writer.
   * @function
   * @returns {BufferWriter|Writer} A {@link BufferWriter} when Buffers are supported, otherwise a {@link Writer}
   */
  Writer.create = util.Buffer
      ? function create_buffer_setup() {
          return (Writer.create = function create_buffer() {
              return new BufferWriter();
          })();
      }
      /* istanbul ignore next */
      : function create_array() {
          return new Writer();
      };

  /**
   * Allocates a buffer of the specified size.
   * @param {number} size Buffer size
   * @returns {Uint8Array} Buffer
   */
  Writer.alloc = function alloc(size) {
      return new util.Array(size);
  };

  // Use Uint8Array buffer pool in the browser, just like node does with buffers
  /* istanbul ignore else */
  if (util.Array !== Array)
      Writer.alloc = util.pool(Writer.alloc, util.Array.prototype.subarray);

  /**
   * Pushes a new operation to the queue.
   * @param {function(Uint8Array, number, *)} fn Function to call
   * @param {number} len Value byte length
   * @param {number} val Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.push = function push(fn, len, val) {
      this.tail = this.tail.next = new Op(fn, len, val);
      this.len += len;
      return this;
  };

  function writeByte(val, buf, pos) {
      buf[pos] = val & 255;
  }

  function writeVarint32(val, buf, pos) {
      while (val > 127) {
          buf[pos++] = val & 127 | 128;
          val >>>= 7;
      }
      buf[pos] = val;
  }

  /**
   * Constructs a new varint writer operation instance.
   * @classdesc Scheduled varint writer operation.
   * @extends Op
   * @constructor
   * @param {number} len Value byte length
   * @param {number} val Value to write
   * @ignore
   */
  function VarintOp(len, val) {
      this.len = len;
      this.next = undefined$1;
      this.val = val;
  }

  VarintOp.prototype = Object.create(Op.prototype);
  VarintOp.prototype.fn = writeVarint32;

  /**
   * Writes an unsigned 32 bit value as a varint.
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.uint32 = function write_uint32(value) {
      // here, the call to this.push has been inlined and a varint specific Op subclass is used.
      // uint32 is by far the most frequently used operation and benefits significantly from this.
      this.len += (this.tail = this.tail.next = new VarintOp(
          (value = value >>> 0)
                  < 128       ? 1
          : value < 16384     ? 2
          : value < 2097152   ? 3
          : value < 268435456 ? 4
          :                     5,
      value)).len;
      return this;
  };

  /**
   * Writes a signed 32 bit value as a varint.
   * @function
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.int32 = function write_int32(value) {
      return value < 0
          ? this.push(writeVarint64, 10, LongBits.fromNumber(value)) // 10 bytes per spec
          : this.uint32(value);
  };

  /**
   * Writes a 32 bit value as a varint, zig-zag encoded.
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.sint32 = function write_sint32(value) {
      return this.uint32((value << 1 ^ value >> 31) >>> 0);
  };

  function writeVarint64(val, buf, pos) {
      while (val.hi) {
          buf[pos++] = val.lo & 127 | 128;
          val.lo = (val.lo >>> 7 | val.hi << 25) >>> 0;
          val.hi >>>= 7;
      }
      while (val.lo > 127) {
          buf[pos++] = val.lo & 127 | 128;
          val.lo = val.lo >>> 7;
      }
      buf[pos++] = val.lo;
  }

  /**
   * Writes an unsigned 64 bit value as a varint.
   * @param {Long|number|string} value Value to write
   * @returns {Writer} `this`
   * @throws {TypeError} If `value` is a string and no long library is present.
   */
  Writer.prototype.uint64 = function write_uint64(value) {
      var bits = LongBits.from(value);
      return this.push(writeVarint64, bits.length(), bits);
  };

  /**
   * Writes a signed 64 bit value as a varint.
   * @function
   * @param {Long|number|string} value Value to write
   * @returns {Writer} `this`
   * @throws {TypeError} If `value` is a string and no long library is present.
   */
  Writer.prototype.int64 = Writer.prototype.uint64;

  /**
   * Writes a signed 64 bit value as a varint, zig-zag encoded.
   * @param {Long|number|string} value Value to write
   * @returns {Writer} `this`
   * @throws {TypeError} If `value` is a string and no long library is present.
   */
  Writer.prototype.sint64 = function write_sint64(value) {
      var bits = LongBits.from(value).zzEncode();
      return this.push(writeVarint64, bits.length(), bits);
  };

  /**
   * Writes a boolish value as a varint.
   * @param {boolean} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.bool = function write_bool(value) {
      return this.push(writeByte, 1, value ? 1 : 0);
  };

  function writeFixed32(val, buf, pos) {
      buf[pos++] =  val         & 255;
      buf[pos++] =  val >>> 8   & 255;
      buf[pos++] =  val >>> 16  & 255;
      buf[pos  ] =  val >>> 24;
  }

  /**
   * Writes an unsigned 32 bit value as fixed 32 bits.
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.fixed32 = function write_fixed32(value) {
      return this.push(writeFixed32, 4, value >>> 0);
  };

  /**
   * Writes a signed 32 bit value as fixed 32 bits.
   * @function
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.sfixed32 = Writer.prototype.fixed32;

  /**
   * Writes an unsigned 64 bit value as fixed 64 bits.
   * @param {Long|number|string} value Value to write
   * @returns {Writer} `this`
   * @throws {TypeError} If `value` is a string and no long library is present.
   */
  Writer.prototype.fixed64 = function write_fixed64(value) {
      var bits = LongBits.from(value);
      return this.push(writeFixed32, 4, bits.lo).push(writeFixed32, 4, bits.hi);
  };

  /**
   * Writes a signed 64 bit value as fixed 64 bits.
   * @function
   * @param {Long|number|string} value Value to write
   * @returns {Writer} `this`
   * @throws {TypeError} If `value` is a string and no long library is present.
   */
  Writer.prototype.sfixed64 = Writer.prototype.fixed64;

  var writeFloat = typeof Float32Array !== "undefined"
      ? (function() {
          var f32 = new Float32Array(1),
              f8b = new Uint8Array(f32.buffer);
          f32[0] = -0;
          return f8b[3] // already le?
              ? function writeFloat_f32(val, buf, pos) {
                  f32[0] = val;
                  buf[pos++] = f8b[0];
                  buf[pos++] = f8b[1];
                  buf[pos++] = f8b[2];
                  buf[pos  ] = f8b[3];
              }
              /* istanbul ignore next */
              : function writeFloat_f32_le(val, buf, pos) {
                  f32[0] = val;
                  buf[pos++] = f8b[3];
                  buf[pos++] = f8b[2];
                  buf[pos++] = f8b[1];
                  buf[pos  ] = f8b[0];
              };
      })()
      /* istanbul ignore next */
      : function writeFloat_ieee754(value, buf, pos) {
          var sign = value < 0 ? 1 : 0;
          if (sign)
              value = -value;
          if (value === 0)
              writeFixed32(1 / value > 0 ? /* positive */ 0 : /* negative 0 */ 2147483648, buf, pos);
          else if (isNaN(value))
              writeFixed32(2147483647, buf, pos);
          else if (value > 3.4028234663852886e+38) // +-Infinity
              writeFixed32((sign << 31 | 2139095040) >>> 0, buf, pos);
          else if (value < 1.1754943508222875e-38) // denormal
              writeFixed32((sign << 31 | Math.round(value / 1.401298464324817e-45)) >>> 0, buf, pos);
          else {
              var exponent = Math.floor(Math.log(value) / Math.LN2),
                  mantissa = Math.round(value * Math.pow(2, -exponent) * 8388608) & 8388607;
              writeFixed32((sign << 31 | exponent + 127 << 23 | mantissa) >>> 0, buf, pos);
          }
      };

  /**
   * Writes a float (32 bit).
   * @function
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.float = function write_float(value) {
      return this.push(writeFloat, 4, value);
  };

  var writeDouble = typeof Float64Array !== "undefined"
      ? (function() {
          var f64 = new Float64Array(1),
              f8b = new Uint8Array(f64.buffer);
          f64[0] = -0;
          return f8b[7] // already le?
              ? function writeDouble_f64(val, buf, pos) {
                  f64[0] = val;
                  buf[pos++] = f8b[0];
                  buf[pos++] = f8b[1];
                  buf[pos++] = f8b[2];
                  buf[pos++] = f8b[3];
                  buf[pos++] = f8b[4];
                  buf[pos++] = f8b[5];
                  buf[pos++] = f8b[6];
                  buf[pos  ] = f8b[7];
              }
              /* istanbul ignore next */
              : function writeDouble_f64_le(val, buf, pos) {
                  f64[0] = val;
                  buf[pos++] = f8b[7];
                  buf[pos++] = f8b[6];
                  buf[pos++] = f8b[5];
                  buf[pos++] = f8b[4];
                  buf[pos++] = f8b[3];
                  buf[pos++] = f8b[2];
                  buf[pos++] = f8b[1];
                  buf[pos  ] = f8b[0];
              };
      })()
      /* istanbul ignore next */
      : function writeDouble_ieee754(value, buf, pos) {
          var sign = value < 0 ? 1 : 0;
          if (sign)
              value = -value;
          if (value === 0) {
              writeFixed32(0, buf, pos);
              writeFixed32(1 / value > 0 ? /* positive */ 0 : /* negative 0 */ 2147483648, buf, pos + 4);
          } else if (isNaN(value)) {
              writeFixed32(4294967295, buf, pos);
              writeFixed32(2147483647, buf, pos + 4);
          } else if (value > 1.7976931348623157e+308) { // +-Infinity
              writeFixed32(0, buf, pos);
              writeFixed32((sign << 31 | 2146435072) >>> 0, buf, pos + 4);
          } else {
              var mantissa;
              if (value < 2.2250738585072014e-308) { // denormal
                  mantissa = value / 5e-324;
                  writeFixed32(mantissa >>> 0, buf, pos);
                  writeFixed32((sign << 31 | mantissa / 4294967296) >>> 0, buf, pos + 4);
              } else {
                  var exponent = Math.floor(Math.log(value) / Math.LN2);
                  if (exponent === 1024)
                      exponent = 1023;
                  mantissa = value * Math.pow(2, -exponent);
                  writeFixed32(mantissa * 4503599627370496 >>> 0, buf, pos);
                  writeFixed32((sign << 31 | exponent + 1023 << 20 | mantissa * 1048576 & 1048575) >>> 0, buf, pos + 4);
              }
          }
      };

  /**
   * Writes a double (64 bit float).
   * @function
   * @param {number} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.double = function write_double(value) {
      return this.push(writeDouble, 8, value);
  };

  var writeBytes = util.Array.prototype.set
      ? function writeBytes_set(val, buf, pos) {
          buf.set(val, pos); // also works for plain array values
      }
      /* istanbul ignore next */
      : function writeBytes_for(val, buf, pos) {
          for (var i = 0; i < val.length; ++i)
              buf[pos + i] = val[i];
      };

  /**
   * Writes a sequence of bytes.
   * @param {Uint8Array|string} value Buffer or base64 encoded string to write
   * @returns {Writer} `this`
   */
  Writer.prototype.bytes = function write_bytes(value) {
      var len = value.length >>> 0;
      if (!len)
          return this.push(writeByte, 1, 0);
      if (util.isString(value)) {
          var buf = Writer.alloc(len = base64.length(value));
          base64.decode(value, buf, 0);
          value = buf;
      }
      return this.uint32(len).push(writeBytes, len, value);
  };

  /**
   * Writes a string.
   * @param {string} value Value to write
   * @returns {Writer} `this`
   */
  Writer.prototype.string = function write_string(value) {
      var len = utf8.length(value);
      return len
          ? this.uint32(len).push(utf8.write, len, value)
          : this.push(writeByte, 1, 0);
  };

  /**
   * Forks this writer's state by pushing it to a stack.
   * Calling {@link Writer#reset|reset} or {@link Writer#ldelim|ldelim} resets the writer to the previous state.
   * @returns {Writer} `this`
   */
  Writer.prototype.fork = function fork() {
      this.states = new State(this);
      this.head = this.tail = new Op(noop, 0, 0);
      this.len = 0;
      return this;
  };

  /**
   * Resets this instance to the last state.
   * @returns {Writer} `this`
   */
  Writer.prototype.reset = function reset() {
      if (this.states) {
          this.head   = this.states.head;
          this.tail   = this.states.tail;
          this.len    = this.states.len;
          this.states = this.states.next;
      } else {
          this.head = this.tail = new Op(noop, 0, 0);
          this.len  = 0;
      }
      return this;
  };

  /**
   * Resets to the last state and appends the fork state's current write length as a varint followed by its operations.
   * @returns {Writer} `this`
   */
  Writer.prototype.ldelim = function ldelim() {
      var head = this.head,
          tail = this.tail,
          len  = this.len;
      this.reset().uint32(len);
      if (len) {
          this.tail.next = head.next; // skip noop
          this.tail = tail;
          this.len += len;
      }
      return this;
  };

  /**
   * Finishes the write operation.
   * @returns {Uint8Array} Finished buffer
   */
  Writer.prototype.finish = function finish() {
      var head = this.head.next, // skip noop
          buf  = this.constructor.alloc(this.len),
          pos  = 0;
      while (head) {
          head.fn(head.val, buf, pos);
          pos += head.len;
          head = head.next;
      }
      // this.head = this.tail = null;
      return buf;
  };

  Writer._configure = function(BufferWriter_) {
      BufferWriter = BufferWriter_;
  };

  },{"13":13}],15:[function(require,module,exports){
  module.exports = BufferWriter;

  // extends Writer
  var Writer = require(14);
  (BufferWriter.prototype = Object.create(Writer.prototype)).constructor = BufferWriter;

  var util = require(13);

  var Buffer = util.Buffer;

  /**
   * Constructs a new buffer writer instance.
   * @classdesc Wire format writer using node buffers.
   * @extends Writer
   * @constructor
   */
  function BufferWriter() {
      Writer.call(this);
  }

  /**
   * Allocates a buffer of the specified size.
   * @param {number} size Buffer size
   * @returns {Buffer} Buffer
   */
  BufferWriter.alloc = function alloc_buffer(size) {
      return (BufferWriter.alloc = util._Buffer_allocUnsafe)(size);
  };

  var writeBytesBuffer = Buffer && Buffer.prototype instanceof Uint8Array && Buffer.prototype.set.name === "set"
      ? function writeBytesBuffer_set(val, buf, pos) {
          buf.set(val, pos); // faster than copy (requires node >= 4 where Buffers extend Uint8Array and set is properly inherited)
                             // also works for plain array values
      }
      /* istanbul ignore next */
      : function writeBytesBuffer_copy(val, buf, pos) {
          if (val.copy) // Buffer values
              val.copy(buf, pos, 0, val.length);
          else for (var i = 0; i < val.length;) // plain array values
              buf[pos++] = val[i++];
      };

  /**
   * @override
   */
  BufferWriter.prototype.bytes = function write_bytes_buffer(value) {
      if (util.isString(value))
          value = util._Buffer_from(value, "base64");
      var len = value.length >>> 0;
      this.uint32(len);
      if (len)
          this.push(writeBytesBuffer, len, value);
      return this;
  };

  function writeStringBuffer(val, buf, pos) {
      if (val.length < 40) // plain js is faster for short strings (probably due to redundant assertions)
          util.utf8.write(val, buf, pos);
      else
          buf.utf8Write(val, pos);
  }

  /**
   * @override
   */
  BufferWriter.prototype.string = function write_string_buffer(value) {
      var len = Buffer.byteLength(value);
      this.uint32(len);
      if (len)
          this.push(writeStringBuffer, len, value);
      return this;
  };


  /**
   * Finishes the write operation.
   * @name BufferWriter#finish
   * @function
   * @returns {Buffer} Finished buffer
   */

  },{"13":13,"14":14}]},{},[7]);

  })(tmp$1);


  var protobuf = tmp$1.protobuf;

  /**
   * @private
   */
  function isBitSet(bits, mask) {
    return (bits & mask) !== 0;
  }

  // Bitmask for checking tile properties
  var childrenBitmasks = [0x01, 0x02, 0x04, 0x08];
  var anyChildBitmask = 0x0f;
  var cacheFlagBitmask = 0x10; // True if there is a child subtree
  var imageBitmask = 0x40;
  var terrainBitmask = 0x80;

  /**
   * Contains information about each tile from a Google Earth Enterprise server
   *
   * @param {Number} bits Bitmask that contains the type of data and available children for each tile.
   * @param {Number} cnodeVersion Version of the request for subtree metadata.
   * @param {Number} imageryVersion Version of the request for imagery tile.
   * @param {Number} terrainVersion Version of the request for terrain tile.
   * @param {Number} imageryProvider Id of imagery provider.
   * @param {Number} terrainProvider Id of terrain provider.
   *
   * @private
   */
  function GoogleEarthEnterpriseTileInformation(
    bits,
    cnodeVersion,
    imageryVersion,
    terrainVersion,
    imageryProvider,
    terrainProvider
  ) {
    this._bits = bits;
    this.cnodeVersion = cnodeVersion;
    this.imageryVersion = imageryVersion;
    this.terrainVersion = terrainVersion;
    this.imageryProvider = imageryProvider;
    this.terrainProvider = terrainProvider;
    this.ancestorHasTerrain = false; // Set it later once we find its parent
    this.terrainState = undefined;
  }

  /**
   * Creates GoogleEarthEnterpriseTileInformation from an object
   *
   * @param {Object} info Object to be cloned
   * @param {GoogleEarthEnterpriseTileInformation} [result] The object onto which to store the result.
   * @returns {GoogleEarthEnterpriseTileInformation} The modified result parameter or a new GoogleEarthEnterpriseTileInformation instance if none was provided.
   */
  GoogleEarthEnterpriseTileInformation.clone = function (info, result) {
    if (!defined(result)) {
      result = new GoogleEarthEnterpriseTileInformation(
        info._bits,
        info.cnodeVersion,
        info.imageryVersion,
        info.terrainVersion,
        info.imageryProvider,
        info.terrainProvider
      );
    } else {
      result._bits = info._bits;
      result.cnodeVersion = info.cnodeVersion;
      result.imageryVersion = info.imageryVersion;
      result.terrainVersion = info.terrainVersion;
      result.imageryProvider = info.imageryProvider;
      result.terrainProvider = info.terrainProvider;
    }
    result.ancestorHasTerrain = info.ancestorHasTerrain;
    result.terrainState = info.terrainState;

    return result;
  };

  /**
   * Sets the parent for the tile
   *
   * @param {GoogleEarthEnterpriseTileInformation} parent Parent tile
   */
  GoogleEarthEnterpriseTileInformation.prototype.setParent = function (parent) {
    this.ancestorHasTerrain = parent.ancestorHasTerrain || this.hasTerrain();
  };

  /**
   * Gets whether a subtree is available
   *
   * @returns {Boolean} true if subtree is available, false otherwise.
   */
  GoogleEarthEnterpriseTileInformation.prototype.hasSubtree = function () {
    return isBitSet(this._bits, cacheFlagBitmask);
  };

  /**
   * Gets whether imagery is available
   *
   * @returns {Boolean} true if imagery is available, false otherwise.
   */
  GoogleEarthEnterpriseTileInformation.prototype.hasImagery = function () {
    return isBitSet(this._bits, imageBitmask);
  };

  /**
   * Gets whether terrain is available
   *
   * @returns {Boolean} true if terrain is available, false otherwise.
   */
  GoogleEarthEnterpriseTileInformation.prototype.hasTerrain = function () {
    return isBitSet(this._bits, terrainBitmask);
  };

  /**
   * Gets whether any children are present
   *
   * @returns {Boolean} true if any children are available, false otherwise.
   */
  GoogleEarthEnterpriseTileInformation.prototype.hasChildren = function () {
    return isBitSet(this._bits, anyChildBitmask);
  };

  /**
   * Gets whether a specified child is available
   *
   * @param {Number} index Index of child tile
   *
   * @returns {Boolean} true if child is available, false otherwise
   */
  GoogleEarthEnterpriseTileInformation.prototype.hasChild = function (index) {
    return isBitSet(this._bits, childrenBitmasks[index]);
  };

  /**
   * Gets bitmask containing children
   *
   * @returns {Number} Children bitmask
   */
  GoogleEarthEnterpriseTileInformation.prototype.getChildBitmask = function () {
    return this._bits & anyChildBitmask;
  };

  function stringToBuffer(str) {
    var len = str.length;
    var buffer = new ArrayBuffer(len);
    var ui8 = new Uint8Array(buffer);
    for (var i = 0; i < len; ++i) {
      ui8[i] = str.charCodeAt(i);
    }

    return buffer;
  }

  // Decodes packet with a key that has been around since the beginning of Google Earth Enterprise
  var defaultKey$1 = stringToBuffer(
    "\x45\xf4\xbd\x0b\x79\xe2\x6a\x45\x22\x05\x92\x2c\x17\xcd\x06\x71\xf8\x49\x10\x46\x67\x51\x00\x42\x25\xc6\xe8\x61\x2c\x66\x29\x08\xc6\x34\xdc\x6a\x62\x25\x79\x0a\x77\x1d\x6d\x69\xd6\xf0\x9c\x6b\x93\xa1\xbd\x4e\x75\xe0\x41\x04\x5b\xdf\x40\x56\x0c\xd9\xbb\x72\x9b\x81\x7c\x10\x33\x53\xee\x4f\x6c\xd4\x71\x05\xb0\x7b\xc0\x7f\x45\x03\x56\x5a\xad\x77\x55\x65\x0b\x33\x92\x2a\xac\x19\x6c\x35\x14\xc5\x1d\x30\x73\xf8\x33\x3e\x6d\x46\x38\x4a\xb4\xdd\xf0\x2e\xdd\x17\x75\x16\xda\x8c\x44\x74\x22\x06\xfa\x61\x22\x0c\x33\x22\x53\x6f\xaf\x39\x44\x0b\x8c\x0e\x39\xd9\x39\x13\x4c\xb9\xbf\x7f\xab\x5c\x8c\x50\x5f\x9f\x22\x75\x78\x1f\xe9\x07\x71\x91\x68\x3b\xc1\xc4\x9b\x7f\xf0\x3c\x56\x71\x48\x82\x05\x27\x55\x66\x59\x4e\x65\x1d\x98\x75\xa3\x61\x46\x7d\x61\x3f\x15\x41\x00\x9f\x14\x06\xd7\xb4\x34\x4d\xce\x13\x87\x46\xb0\x1a\xd5\x05\x1c\xb8\x8a\x27\x7b\x8b\xdc\x2b\xbb\x4d\x67\x30\xc8\xd1\xf6\x5c\x8f\x50\xfa\x5b\x2f\x46\x9b\x6e\x35\x18\x2f\x27\x43\x2e\xeb\x0a\x0c\x5e\x10\x05\x10\xa5\x73\x1b\x65\x34\xe5\x6c\x2e\x6a\x43\x27\x63\x14\x23\x55\xa9\x3f\x71\x7b\x67\x43\x7d\x3a\xaf\xcd\xe2\x54\x55\x9c\xfd\x4b\xc6\xe2\x9f\x2f\x28\xed\xcb\x5c\xc6\x2d\x66\x07\x88\xa7\x3b\x2f\x18\x2a\x22\x4e\x0e\xb0\x6b\x2e\xdd\x0d\x95\x7d\x7d\x47\xba\x43\xb2\x11\xb2\x2b\x3e\x4d\xaa\x3e\x7d\xe6\xce\x49\x89\xc6\xe6\x78\x0c\x61\x31\x05\x2d\x01\xa4\x4f\xa5\x7e\x71\x20\x88\xec\x0d\x31\xe8\x4e\x0b\x00\x6e\x50\x68\x7d\x17\x3d\x08\x0d\x17\x95\xa6\x6e\xa3\x68\x97\x24\x5b\x6b\xf3\x17\x23\xf3\xb6\x73\xb3\x0d\x0b\x40\xc0\x9f\xd8\x04\x51\x5d\xfa\x1a\x17\x22\x2e\x15\x6a\xdf\x49\x00\xb9\xa0\x77\x55\xc6\xef\x10\x6a\xbf\x7b\x47\x4c\x7f\x83\x17\x05\xee\xdc\xdc\x46\x85\xa9\xad\x53\x07\x2b\x53\x34\x06\x07\xff\x14\x94\x59\x19\x02\xe4\x38\xe8\x31\x83\x4e\xb9\x58\x46\x6b\xcb\x2d\x23\x86\x92\x70\x00\x35\x88\x22\xcf\x31\xb2\x26\x2f\xe7\xc3\x75\x2d\x36\x2c\x72\x74\xb0\x23\x47\xb7\xd3\xd1\x26\x16\x85\x37\x72\xe2\x00\x8c\x44\xcf\x10\xda\x33\x2d\x1a\xde\x60\x86\x69\x23\x69\x2a\x7c\xcd\x4b\x51\x0d\x95\x54\x39\x77\x2e\x29\xea\x1b\xa6\x50\xa2\x6a\x8f\x6f\x50\x99\x5c\x3e\x54\xfb\xef\x50\x5b\x0b\x07\x45\x17\x89\x6d\x28\x13\x77\x37\x1d\xdb\x8e\x1e\x4a\x05\x66\x4a\x6f\x99\x20\xe5\x70\xe2\xb9\x71\x7e\x0c\x6d\x49\x04\x2d\x7a\xfe\x72\xc7\xf2\x59\x30\x8f\xbb\x02\x5d\x73\xe5\xc9\x20\xea\x78\xec\x20\x90\xf0\x8a\x7f\x42\x17\x7c\x47\x19\x60\xb0\x16\xbd\x26\xb7\x71\xb6\xc7\x9f\x0e\xd1\x33\x82\x3d\xd3\xab\xee\x63\x99\xc8\x2b\x53\xa0\x44\x5c\x71\x01\xc6\xcc\x44\x1f\x32\x4f\x3c\xca\xc0\x29\x3d\x52\xd3\x61\x19\x58\xa9\x7d\x65\xb4\xdc\xcf\x0d\xf4\x3d\xf1\x08\xa9\x42\xda\x23\x09\xd8\xbf\x5e\x50\x49\xf8\x4d\xc0\xcb\x47\x4c\x1c\x4f\xf7\x7b\x2b\xd8\x16\x18\xc5\x31\x92\x3b\xb5\x6f\xdc\x6c\x0d\x92\x88\x16\xd1\x9e\xdb\x3f\xe2\xe9\xda\x5f\xd4\x84\xe2\x46\x61\x5a\xde\x1c\x55\xcf\xa4\x00\xbe\xfd\xce\x67\xf1\x4a\x69\x1c\x97\xe6\x20\x48\xd8\x5d\x7f\x7e\xae\x71\x20\x0e\x4e\xae\xc0\x56\xa9\x91\x01\x3c\x82\x1d\x0f\x72\xe7\x76\xec\x29\x49\xd6\x5d\x2d\x83\xe3\xdb\x36\x06\xa9\x3b\x66\x13\x97\x87\x6a\xd5\xb6\x3d\x50\x5e\x52\xb9\x4b\xc7\x73\x57\x78\xc9\xf4\x2e\x59\x07\x95\x93\x6f\xd0\x4b\x17\x57\x19\x3e\x27\x27\xc7\x60\xdb\x3b\xed\x9a\x0e\x53\x44\x16\x3e\x3f\x8d\x92\x6d\x77\xa2\x0a\xeb\x3f\x52\xa8\xc6\x55\x5e\x31\x49\x37\x85\xf4\xc5\x1f\x26\x2d\xa9\x1c\xbf\x8b\x27\x54\xda\xc3\x6a\x20\xe5\x2a\x78\x04\xb0\xd6\x90\x70\x72\xaa\x8b\x68\xbd\x88\xf7\x02\x5f\x48\xb1\x7e\xc0\x58\x4c\x3f\x66\x1a\xf9\x3e\xe1\x65\xc0\x70\xa7\xcf\x38\x69\xaf\xf0\x56\x6c\x64\x49\x9c\x27\xad\x78\x74\x4f\xc2\x87\xde\x56\x39\x00\xda\x77\x0b\xcb\x2d\x1b\x89\xfb\x35\x4f\x02\xf5\x08\x51\x13\x60\xc1\x0a\x5a\x47\x4d\x26\x1c\x33\x30\x78\xda\xc0\x9c\x46\x47\xe2\x5b\x79\x60\x49\x6e\x37\x67\x53\x0a\x3e\xe9\xec\x46\x39\xb2\xf1\x34\x0d\xc6\x84\x53\x75\x6e\xe1\x0c\x59\xd9\x1e\xde\x29\x85\x10\x7b\x49\x49\xa5\x77\x79\xbe\x49\x56\x2e\x36\xe7\x0b\x3a\xbb\x4f\x03\x62\x7b\xd2\x4d\x31\x95\x2f\xbd\x38\x7b\xa8\x4f\x21\xe1\xec\x46\x70\x76\x95\x7d\x29\x22\x78\x88\x0a\x90\xdd\x9d\x5c\xda\xde\x19\x51\xcf\xf0\xfc\x59\x52\x65\x7c\x33\x13\xdf\xf3\x48\xda\xbb\x2a\x75\xdb\x60\xb2\x02\x15\xd4\xfc\x19\xed\x1b\xec\x7f\x35\xa8\xff\x28\x31\x07\x2d\x12\xc8\xdc\x88\x46\x7c\x8a\x5b\x22"
  );

  /**
   * Provides metadata using the Google Earth Enterprise REST API. This is used by the GoogleEarthEnterpriseImageryProvider
   *  and GoogleEarthEnterpriseTerrainProvider to share metadata requests.
   *
   * @alias GoogleEarthEnterpriseMetadata
   * @constructor
   *
   * @param {Resource|String} resourceOrUrl The url of the Google Earth Enterprise server hosting the imagery
   *
   * @see GoogleEarthEnterpriseImageryProvider
   * @see GoogleEarthEnterpriseTerrainProvider
   *
   */
  function GoogleEarthEnterpriseMetadata(resourceOrUrl) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("resourceOrUrl", resourceOrUrl);
    //>>includeEnd('debug');

    var url = resourceOrUrl;

    if (typeof url !== "string" && !(url instanceof Resource)) {
      //>>includeStart('debug', pragmas.debug);
      Check.typeOf.string("resourceOrUrl.url", resourceOrUrl.url);
      //>>includeEnd('debug');

      url = resourceOrUrl.url;
    }

    var resource = Resource.createIfNeeded(url);
    resource.appendForwardSlash();
    this._resource = resource;

    /**
     * True if imagery is available.
     * @type {Boolean}
     * @default true
     */
    this.imageryPresent = true;

    /**
     * True if imagery is sent as a protocol buffer, false if sent as plain images. If undefined we will try both.
     * @type {Boolean}
     * @default undefined
     */
    this.protoImagery = undefined;

    /**
     * True if terrain is available.
     * @type {Boolean}
     * @default true
     */
    this.terrainPresent = true;

    /**
     * Exponent used to compute constant to calculate negative height values.
     * @type {Number}
     * @default 32
     */
    this.negativeAltitudeExponentBias = 32;

    /**
     * Threshold where any numbers smaller are actually negative values. They are multiplied by -2^negativeAltitudeExponentBias.
     * @type {Number}
     * @default EPSILON12
     */
    this.negativeAltitudeThreshold = CesiumMath.EPSILON12;

    /**
     * Dictionary of provider id to copyright strings.
     * @type {Object}
     * @default {}
     */
    this.providers = {};

    /**
     * Key used to decode packets
     * @type {ArrayBuffer}
     */
    this.key = undefined;

    this._quadPacketVersion = 1;

    this._tileInfo = {};
    this._subtreePromises = {};

    var that = this;
    this._readyPromise = requestDbRoot(this)
      .then(function () {
        return that.getQuadTreePacket("", that._quadPacketVersion);
      })
      .then(function () {
        return true;
      })
      .otherwise(function (e) {
        var message =
          "An error occurred while accessing " +
          getMetadataResource(that, "", 1).url +
          ".";
        return when.reject(new RuntimeError(message));
      });
  }

  Object.defineProperties(GoogleEarthEnterpriseMetadata.prototype, {
    /**
     * Gets the name of the Google Earth Enterprise server.
     * @memberof GoogleEarthEnterpriseMetadata.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource.url;
      },
    },

    /**
     * Gets the proxy used for metadata requests.
     * @memberof GoogleEarthEnterpriseMetadata.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the resource used for metadata requests.
     * @memberof GoogleEarthEnterpriseMetadata.prototype
     * @type {Resource}
     * @readonly
     */
    resource: {
      get: function () {
        return this._resource;
      },
    },

    /**
     * Gets a promise that resolves to true when the metadata is ready for use.
     * @memberof GoogleEarthEnterpriseMetadata.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },
  });

  /**
   * Converts a tiles (x, y, level) position into a quadkey used to request an image
   * from a Google Earth Enterprise server.
   *
   * @param {Number} x The tile's x coordinate.
   * @param {Number} y The tile's y coordinate.
   * @param {Number} level The tile's zoom level.
   *
   * @see GoogleEarthEnterpriseMetadata#quadKeyToTileXY
   */
  GoogleEarthEnterpriseMetadata.tileXYToQuadKey = function (x, y, level) {
    var quadkey = "";
    for (var i = level; i >= 0; --i) {
      var bitmask = 1 << i;
      var digit = 0;

      // Tile Layout
      // ___ ___
      //|   |   |
      //| 3 | 2 |
      //|-------|
      //| 0 | 1 |
      //|___|___|
      //

      if (!isBitSet(y, bitmask)) {
        // Top Row
        digit |= 2;
        if (!isBitSet(x, bitmask)) {
          // Right to left
          digit |= 1;
        }
      } else if (isBitSet(x, bitmask)) {
        // Left to right
        digit |= 1;
      }

      quadkey += digit;
    }
    return quadkey;
  };

  /**
   * Converts a tile's quadkey used to request an image from a Google Earth Enterprise server into the
   * (x, y, level) position.
   *
   * @param {String} quadkey The tile's quad key
   *
   * @see GoogleEarthEnterpriseMetadata#tileXYToQuadKey
   */
  GoogleEarthEnterpriseMetadata.quadKeyToTileXY = function (quadkey) {
    var x = 0;
    var y = 0;
    var level = quadkey.length - 1;
    for (var i = level; i >= 0; --i) {
      var bitmask = 1 << i;
      var digit = +quadkey[level - i];

      if (isBitSet(digit, 2)) {
        // Top Row
        if (!isBitSet(digit, 1)) {
          // // Right to left
          x |= bitmask;
        }
      } else {
        y |= bitmask;
        if (isBitSet(digit, 1)) {
          // Left to right
          x |= bitmask;
        }
      }
    }
    return {
      x: x,
      y: y,
      level: level,
    };
  };

  GoogleEarthEnterpriseMetadata.prototype.isValid = function (quadKey) {
    var info = this.getTileInformationFromQuadKey(quadKey);
    if (defined(info)) {
      return info !== null;
    }

    var valid = true;
    var q = quadKey;
    var last;
    while (q.length > 1) {
      last = q.substring(q.length - 1);
      q = q.substring(0, q.length - 1);
      info = this.getTileInformationFromQuadKey(q);
      if (defined(info)) {
        if (!info.hasSubtree() && !info.hasChild(parseInt(last))) {
          // We have no subtree or child available at some point in this node's ancestry
          valid = false;
        }

        break;
      } else if (info === null) {
        // Some node in the ancestry was loaded and said there wasn't a subtree
        valid = false;
        break;
      }
    }

    return valid;
  };

  var taskProcessor$1 = new TaskProcessor(
    "decodeGoogleEarthEnterprisePacket",
    Number.POSITIVE_INFINITY
  );

  /**
   * Retrieves a Google Earth Enterprise quadtree packet.
   *
   * @param {String} [quadKey=''] The quadkey to retrieve the packet for.
   * @param {Number} [version=1] The cnode version to be used in the request.
   * @param {Request} [request] The request object. Intended for internal use only.
   *
   * @private
   */
  GoogleEarthEnterpriseMetadata.prototype.getQuadTreePacket = function (
    quadKey,
    version,
    request
  ) {
    version = defaultValue(version, 1);
    quadKey = defaultValue(quadKey, "");
    var resource = getMetadataResource(this, quadKey, version, request);

    var promise = resource.fetchArrayBuffer();

    if (!defined(promise)) {
      return undefined; // Throttled
    }

    var tileInfo = this._tileInfo;
    var key = this.key;
    return promise.then(function (metadata) {
      var decodePromise = taskProcessor$1.scheduleTask(
        {
          buffer: metadata,
          quadKey: quadKey,
          type: "Metadata",
          key: key,
        },
        [metadata]
      );

      return decodePromise.then(function (result) {
        var root;
        var topLevelKeyLength = -1;
        if (quadKey !== "") {
          // Root tile has no data except children bits, so put them into the tile info
          topLevelKeyLength = quadKey.length + 1;
          var top = result[quadKey];
          root = tileInfo[quadKey];
          root._bits |= top._bits;

          delete result[quadKey];
        }

        // Copy the resulting objects into tileInfo
        // Make sure we start with shorter quadkeys first, so we know the parents have
        //  already been processed. Otherwise we can lose ancestorHasTerrain along the way.
        var keys = Object.keys(result);
        keys.sort(function (a, b) {
          return a.length - b.length;
        });
        var keysLength = keys.length;
        for (var i = 0; i < keysLength; ++i) {
          var key = keys[i];
          var r = result[key];
          if (r !== null) {
            var info = GoogleEarthEnterpriseTileInformation.clone(result[key]);
            var keyLength = key.length;
            if (keyLength === topLevelKeyLength) {
              info.setParent(root);
            } else if (keyLength > 1) {
              var parent = tileInfo[key.substring(0, key.length - 1)];
              info.setParent(parent);
            }
            tileInfo[key] = info;
          } else {
            tileInfo[key] = null;
          }
        }
      });
    });
  };

  /**
   * Populates the metadata subtree down to the specified tile.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   *
   * @returns {Promise<GoogleEarthEnterpriseTileInformation>} A promise that resolves to the tile info for the requested quad key
   *
   * @private
   */
  GoogleEarthEnterpriseMetadata.prototype.populateSubtree = function (
    x,
    y,
    level,
    request
  ) {
    var quadkey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
    return populateSubtree(this, quadkey, request);
  };

  function populateSubtree(that, quadKey, request) {
    var tileInfo = that._tileInfo;
    var q = quadKey;
    var t = tileInfo[q];
    // If we have tileInfo make sure sure it is not a node with a subtree that's not loaded
    if (defined(t) && (!t.hasSubtree() || t.hasChildren())) {
      return t;
    }

    while (t === undefined && q.length > 1) {
      q = q.substring(0, q.length - 1);
      t = tileInfo[q];
    }

    var subtreeRequest;
    var subtreePromises = that._subtreePromises;
    var promise = subtreePromises[q];
    if (defined(promise)) {
      return promise.then(function () {
        // Recursively call this in case we need multiple subtree requests
        subtreeRequest = new Request({
          throttle: request.throttle,
          throttleByServer: request.throttleByServer,
          type: request.type,
          priorityFunction: request.priorityFunction,
        });
        return populateSubtree(that, quadKey, subtreeRequest);
      });
    }

    // t is either
    //   null so one of its parents was a leaf node, so this tile doesn't exist
    //   exists but doesn't have a subtree to request
    //   undefined so no parent exists - this shouldn't ever happen once the provider is ready
    if (!defined(t) || !t.hasSubtree()) {
      return when.reject(
        new RuntimeError("Couldn't load metadata for tile " + quadKey)
      );
    }

    // We need to split up the promise here because when will execute syncronously if getQuadTreePacket
    //  is already resolved (like in the tests), so subtreePromises will never get cleared out.
    //  Only the initial request will also remove the promise from subtreePromises.
    promise = that.getQuadTreePacket(q, t.cnodeVersion, request);
    if (!defined(promise)) {
      return undefined;
    }
    subtreePromises[q] = promise;

    return promise
      .then(function () {
        // Recursively call this in case we need multiple subtree requests
        subtreeRequest = new Request({
          throttle: request.throttle,
          throttleByServer: request.throttleByServer,
          type: request.type,
          priorityFunction: request.priorityFunction,
        });
        return populateSubtree(that, quadKey, subtreeRequest);
      })
      .always(function () {
        delete subtreePromises[q];
      });
  }

  /**
   * Gets information about a tile
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @returns {GoogleEarthEnterpriseTileInformation|undefined} Information about the tile or undefined if it isn't loaded.
   *
   * @private
   */
  GoogleEarthEnterpriseMetadata.prototype.getTileInformation = function (
    x,
    y,
    level
  ) {
    var quadkey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
    return this._tileInfo[quadkey];
  };

  /**
   * Gets information about a tile from a quadKey
   *
   * @param {String} quadkey The quadkey for the tile
   * @returns {GoogleEarthEnterpriseTileInformation|undefined} Information about the tile or undefined if it isn't loaded.
   *
   * @private
   */
  GoogleEarthEnterpriseMetadata.prototype.getTileInformationFromQuadKey = function (
    quadkey
  ) {
    return this._tileInfo[quadkey];
  };

  function getMetadataResource(that, quadKey, version, request) {
    return that._resource.getDerivedResource({
      url: "flatfile?q2-0" + quadKey + "-q." + version.toString(),
      request: request,
    });
  }

  var dbrootParser;
  var dbrootParserPromise;
  function requestDbRoot(that) {
    var resource = that._resource.getDerivedResource({
      url: "dbRoot.v5",
      queryParameters: {
        output: "proto",
      },
    });

    if (!defined(dbrootParserPromise)) {
      var url = buildModuleUrl("ThirdParty/google-earth-dbroot-parser.js");
      var oldValue = window.cesiumGoogleEarthDbRootParser;
      dbrootParserPromise = loadAndExecuteScript(url).then(function () {
        dbrootParser = window.cesiumGoogleEarthDbRootParser(protobuf);
        if (defined(oldValue)) {
          window.cesiumGoogleEarthDbRootParser = oldValue;
        } else {
          delete window.cesiumGoogleEarthDbRootParser;
        }
      });
    }

    return dbrootParserPromise
      .then(function () {
        return resource.fetchArrayBuffer();
      })
      .then(function (buf) {
        var encryptedDbRootProto = dbrootParser.EncryptedDbRootProto.decode(
          new Uint8Array(buf)
        );

        var byteArray = encryptedDbRootProto.encryptionData;
        var offset = byteArray.byteOffset;
        var end = offset + byteArray.byteLength;
        var key = (that.key = byteArray.buffer.slice(offset, end));

        byteArray = encryptedDbRootProto.dbrootData;
        offset = byteArray.byteOffset;
        end = offset + byteArray.byteLength;
        var dbRootCompressed = byteArray.buffer.slice(offset, end);
        return taskProcessor$1.scheduleTask(
          {
            buffer: dbRootCompressed,
            type: "DbRoot",
            key: key,
          },
          [dbRootCompressed]
        );
      })
      .then(function (result) {
        var dbRoot = dbrootParser.DbRootProto.decode(
          new Uint8Array(result.buffer)
        );
        that.imageryPresent = defaultValue(
          dbRoot.imageryPresent,
          that.imageryPresent
        );
        that.protoImagery = dbRoot.protoImagery;
        that.terrainPresent = defaultValue(
          dbRoot.terrainPresent,
          that.terrainPresent
        );
        if (defined(dbRoot.endSnippet) && defined(dbRoot.endSnippet.model)) {
          var model = dbRoot.endSnippet.model;
          that.negativeAltitudeExponentBias = defaultValue(
            model.negativeAltitudeExponentBias,
            that.negativeAltitudeExponentBias
          );
          that.negativeAltitudeThreshold = defaultValue(
            model.compressedNegativeAltitudeThreshold,
            that.negativeAltitudeThreshold
          );
        }
        if (defined(dbRoot.databaseVersion)) {
          that._quadPacketVersion = defaultValue(
            dbRoot.databaseVersion.quadtreeVersion,
            that._quadPacketVersion
          );
        }
        var providers = that.providers;
        var providerInfo = defaultValue(dbRoot.providerInfo, []);
        var count = providerInfo.length;
        for (var i = 0; i < count; ++i) {
          var provider = providerInfo[i];
          var copyrightString = provider.copyrightString;
          if (defined(copyrightString)) {
            providers[provider.providerId] = new Credit(copyrightString.value);
          }
        }
      })
      .otherwise(function () {
        // Just eat the error and use the default values.
        console.log("Failed to retrieve " + resource.url + ". Using defaults.");
        that.key = defaultKey$1;
      });
  }

  /**
   * Terrain data for a single tile from a Google Earth Enterprise server.
   *
   * @alias GoogleEarthEnterpriseTerrainData
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {ArrayBuffer} options.buffer The buffer containing terrain data.
   * @param {Number} options.negativeAltitudeExponentBias Multiplier for negative terrain heights that are encoded as very small positive values.
   * @param {Number} options.negativeElevationThreshold Threshold for negative values
   * @param {Number} [options.childTileMask=15] A bit mask indicating which of this tile's four children exist.
   *                 If a child's bit is set, geometry will be requested for that tile as well when it
   *                 is needed.  If the bit is cleared, the child tile is not requested and geometry is
   *                 instead upsampled from the parent.  The bit values are as follows:
   *                 <table>
   *                  <tr><th>Bit Position</th><th>Bit Value</th><th>Child Tile</th></tr>
   *                  <tr><td>0</td><td>1</td><td>Southwest</td></tr>
   *                  <tr><td>1</td><td>2</td><td>Southeast</td></tr>
   *                  <tr><td>2</td><td>4</td><td>Northeast</td></tr>
   *                  <tr><td>3</td><td>8</td><td>Northwest</td></tr>
   *                 </table>
   * @param {Boolean} [options.createdByUpsampling=false] True if this instance was created by upsampling another instance;
   *                  otherwise, false.
   * @param {Credit[]} [options.credits] Array of credits for this tile.
   *
   *
   * @example
   * var buffer = ...
   * var childTileMask = ...
   * var terrainData = new Cesium.GoogleEarthEnterpriseTerrainData({
   *   buffer : heightBuffer,
   *   childTileMask : childTileMask
   * });
   *
   * @see TerrainData
   * @see HeightmapTerrainData
   * @see QuantizedMeshTerrainData
   */
  function GoogleEarthEnterpriseTerrainData(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options.buffer", options.buffer);
    Check.typeOf.number(
      "options.negativeAltitudeExponentBias",
      options.negativeAltitudeExponentBias
    );
    Check.typeOf.number(
      "options.negativeElevationThreshold",
      options.negativeElevationThreshold
    );
    //>>includeEnd('debug');

    this._buffer = options.buffer;
    this._credits = options.credits;
    this._negativeAltitudeExponentBias = options.negativeAltitudeExponentBias;
    this._negativeElevationThreshold = options.negativeElevationThreshold;

    // Convert from google layout to layout of other providers
    // 3 2 -> 2 3
    // 0 1 -> 0 1
    var googleChildTileMask = defaultValue(options.childTileMask, 15);
    var childTileMask = googleChildTileMask & 3; // Bottom row is identical
    childTileMask |= googleChildTileMask & 4 ? 8 : 0; // NE
    childTileMask |= googleChildTileMask & 8 ? 4 : 0; // NW

    this._childTileMask = childTileMask;

    this._createdByUpsampling = defaultValue(options.createdByUpsampling, false);

    this._skirtHeight = undefined;
    this._bufferType = this._buffer.constructor;
    this._mesh = undefined;
    this._minimumHeight = undefined;
    this._maximumHeight = undefined;
  }

  Object.defineProperties(GoogleEarthEnterpriseTerrainData.prototype, {
    /**
     * An array of credits for this tile
     * @memberof GoogleEarthEnterpriseTerrainData.prototype
     * @type {Credit[]}
     */
    credits: {
      get: function () {
        return this._credits;
      },
    },
    /**
     * The water mask included in this terrain data, if any.  A water mask is a rectangular
     * Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
     * Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
     * @memberof GoogleEarthEnterpriseTerrainData.prototype
     * @type {Uint8Array|HTMLImageElement|HTMLCanvasElement}
     */
    waterMask: {
      get: function () {
        return undefined;
      },
    },
  });

  var taskProcessor$2 = new TaskProcessor(
    "createVerticesFromGoogleEarthEnterpriseBuffer"
  );

  var nativeRectangleScratch = new Rectangle();
  var rectangleScratch$1 = new Rectangle();

  /**
   * Creates a {@link TerrainMesh} from this terrain data.
   *
   * @private
   *
   * @param {TilingScheme} tilingScheme The tiling scheme to which this tile belongs.
   * @param {Number} x The X coordinate of the tile for which to create the terrain data.
   * @param {Number} y The Y coordinate of the tile for which to create the terrain data.
   * @param {Number} level The level of the tile for which to create the terrain data.
   * @param {Number} [exaggeration=1.0] The scale used to exaggerate the terrain.
   * @returns {Promise.<TerrainMesh>|undefined} A promise for the terrain mesh, or undefined if too many
   *          asynchronous mesh creations are already in progress and the operation should
   *          be retried later.
   */
  GoogleEarthEnterpriseTerrainData.prototype.createMesh = function (
    tilingScheme,
    x,
    y,
    level,
    exaggeration
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("tilingScheme", tilingScheme);
    Check.typeOf.number("x", x);
    Check.typeOf.number("y", y);
    Check.typeOf.number("level", level);
    //>>includeEnd('debug');

    var ellipsoid = tilingScheme.ellipsoid;
    tilingScheme.tileXYToNativeRectangle(x, y, level, nativeRectangleScratch);
    tilingScheme.tileXYToRectangle(x, y, level, rectangleScratch$1);
    exaggeration = defaultValue(exaggeration, 1.0);

    // Compute the center of the tile for RTC rendering.
    var center = ellipsoid.cartographicToCartesian(
      Rectangle.center(rectangleScratch$1)
    );

    var levelZeroMaxError = 40075.16; // From Google's Doc
    var thisLevelMaxError = levelZeroMaxError / (1 << level);
    this._skirtHeight = Math.min(thisLevelMaxError * 8.0, 1000.0);

    var verticesPromise = taskProcessor$2.scheduleTask({
      buffer: this._buffer,
      nativeRectangle: nativeRectangleScratch,
      rectangle: rectangleScratch$1,
      relativeToCenter: center,
      ellipsoid: ellipsoid,
      skirtHeight: this._skirtHeight,
      exaggeration: exaggeration,
      includeWebMercatorT: true,
      negativeAltitudeExponentBias: this._negativeAltitudeExponentBias,
      negativeElevationThreshold: this._negativeElevationThreshold,
    });

    if (!defined(verticesPromise)) {
      // Postponed
      return undefined;
    }

    var that = this;
    return verticesPromise.then(function (result) {
      // Clone complex result objects because the transfer from the web worker
      // has stripped them down to JSON-style objects.
      that._mesh = new TerrainMesh(
        center,
        new Float32Array(result.vertices),
        new Uint16Array(result.indices),
        result.indexCountWithoutSkirts,
        result.vertexCountWithoutSkirts,
        result.minimumHeight,
        result.maximumHeight,
        BoundingSphere.clone(result.boundingSphere3D),
        Cartesian3.clone(result.occludeePointInScaledSpace),
        result.numberOfAttributes,
        OrientedBoundingBox.clone(result.orientedBoundingBox),
        TerrainEncoding.clone(result.encoding),
        exaggeration,
        result.westIndicesSouthToNorth,
        result.southIndicesEastToWest,
        result.eastIndicesNorthToSouth,
        result.northIndicesWestToEast
      );

      that._minimumHeight = result.minimumHeight;
      that._maximumHeight = result.maximumHeight;

      // Free memory received from server after mesh is created.
      that._buffer = undefined;
      return that._mesh;
    });
  };

  /**
   * Computes the terrain height at a specified longitude and latitude.
   *
   * @param {Rectangle} rectangle The rectangle covered by this terrain data.
   * @param {Number} longitude The longitude in radians.
   * @param {Number} latitude The latitude in radians.
   * @returns {Number} The terrain height at the specified position.  If the position
   *          is outside the rectangle, this method will extrapolate the height, which is likely to be wildly
   *          incorrect for positions far outside the rectangle.
   */
  GoogleEarthEnterpriseTerrainData.prototype.interpolateHeight = function (
    rectangle,
    longitude,
    latitude
  ) {
    var u = CesiumMath.clamp(
      (longitude - rectangle.west) / rectangle.width,
      0.0,
      1.0
    );
    var v = CesiumMath.clamp(
      (latitude - rectangle.south) / rectangle.height,
      0.0,
      1.0
    );

    if (!defined(this._mesh)) {
      return interpolateHeight$2(this, u, v, rectangle);
    }

    return interpolateMeshHeight$2(this, u, v);
  };

  var upsampleTaskProcessor$1 = new TaskProcessor("upsampleQuantizedTerrainMesh");

  /**
   * Upsamples this terrain data for use by a descendant tile.  The resulting instance will contain a subset of the
   * height samples in this instance, interpolated if necessary.
   *
   * @param {TilingScheme} tilingScheme The tiling scheme of this terrain data.
   * @param {Number} thisX The X coordinate of this tile in the tiling scheme.
   * @param {Number} thisY The Y coordinate of this tile in the tiling scheme.
   * @param {Number} thisLevel The level of this tile in the tiling scheme.
   * @param {Number} descendantX The X coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantY The Y coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantLevel The level within the tiling scheme of the descendant tile for which we are upsampling.
   * @returns {Promise.<HeightmapTerrainData>|undefined} A promise for upsampled heightmap terrain data for the descendant tile,
   *          or undefined if too many asynchronous upsample operations are in progress and the request has been
   *          deferred.
   */
  GoogleEarthEnterpriseTerrainData.prototype.upsample = function (
    tilingScheme,
    thisX,
    thisY,
    thisLevel,
    descendantX,
    descendantY,
    descendantLevel
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("tilingScheme", tilingScheme);
    Check.typeOf.number("thisX", thisX);
    Check.typeOf.number("thisY", thisY);
    Check.typeOf.number("thisLevel", thisLevel);
    Check.typeOf.number("descendantX", descendantX);
    Check.typeOf.number("descendantY", descendantY);
    Check.typeOf.number("descendantLevel", descendantLevel);
    var levelDifference = descendantLevel - thisLevel;
    if (levelDifference > 1) {
      throw new DeveloperError(
        "Upsampling through more than one level at a time is not currently supported."
      );
    }
    //>>includeEnd('debug');

    var mesh = this._mesh;
    if (!defined(this._mesh)) {
      return undefined;
    }

    var isEastChild = thisX * 2 !== descendantX;
    var isNorthChild = thisY * 2 === descendantY;

    var ellipsoid = tilingScheme.ellipsoid;
    var childRectangle = tilingScheme.tileXYToRectangle(
      descendantX,
      descendantY,
      descendantLevel
    );

    var upsamplePromise = upsampleTaskProcessor$1.scheduleTask({
      vertices: mesh.vertices,
      indices: mesh.indices,
      indexCountWithoutSkirts: mesh.indexCountWithoutSkirts,
      vertexCountWithoutSkirts: mesh.vertexCountWithoutSkirts,
      encoding: mesh.encoding,
      minimumHeight: this._minimumHeight,
      maximumHeight: this._maximumHeight,
      isEastChild: isEastChild,
      isNorthChild: isNorthChild,
      childRectangle: childRectangle,
      ellipsoid: ellipsoid,
      exaggeration: mesh.exaggeration,
    });

    if (!defined(upsamplePromise)) {
      // Postponed
      return undefined;
    }

    var that = this;
    return upsamplePromise.then(function (result) {
      var quantizedVertices = new Uint16Array(result.vertices);
      var indicesTypedArray = IndexDatatype$1.createTypedArray(
        quantizedVertices.length / 3,
        result.indices
      );

      var skirtHeight = that._skirtHeight;

      // Use QuantizedMeshTerrainData since we have what we need already parsed
      return new QuantizedMeshTerrainData({
        quantizedVertices: quantizedVertices,
        indices: indicesTypedArray,
        minimumHeight: result.minimumHeight,
        maximumHeight: result.maximumHeight,
        boundingSphere: BoundingSphere.clone(result.boundingSphere),
        orientedBoundingBox: OrientedBoundingBox.clone(
          result.orientedBoundingBox
        ),
        horizonOcclusionPoint: Cartesian3.clone(result.horizonOcclusionPoint),
        westIndices: result.westIndices,
        southIndices: result.southIndices,
        eastIndices: result.eastIndices,
        northIndices: result.northIndices,
        westSkirtHeight: skirtHeight,
        southSkirtHeight: skirtHeight,
        eastSkirtHeight: skirtHeight,
        northSkirtHeight: skirtHeight,
        childTileMask: 0,
        createdByUpsampling: true,
        credits: that._credits,
      });
    });
  };

  /**
   * Determines if a given child tile is available, based on the
   * {@link HeightmapTerrainData.childTileMask}.  The given child tile coordinates are assumed
   * to be one of the four children of this tile.  If non-child tile coordinates are
   * given, the availability of the southeast child tile is returned.
   *
   * @param {Number} thisX The tile X coordinate of this (the parent) tile.
   * @param {Number} thisY The tile Y coordinate of this (the parent) tile.
   * @param {Number} childX The tile X coordinate of the child tile to check for availability.
   * @param {Number} childY The tile Y coordinate of the child tile to check for availability.
   * @returns {Boolean} True if the child tile is available; otherwise, false.
   */
  GoogleEarthEnterpriseTerrainData.prototype.isChildAvailable = function (
    thisX,
    thisY,
    childX,
    childY
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("thisX", thisX);
    Check.typeOf.number("thisY", thisY);
    Check.typeOf.number("childX", childX);
    Check.typeOf.number("childY", childY);
    //>>includeEnd('debug');

    var bitNumber = 2; // northwest child
    if (childX !== thisX * 2) {
      ++bitNumber; // east child
    }
    if (childY !== thisY * 2) {
      bitNumber -= 2; // south child
    }

    return (this._childTileMask & (1 << bitNumber)) !== 0;
  };

  /**
   * Gets a value indicating whether or not this terrain data was created by upsampling lower resolution
   * terrain data.  If this value is false, the data was obtained from some other source, such
   * as by downloading it from a remote server.  This method should return true for instances
   * returned from a call to {@link HeightmapTerrainData#upsample}.
   *
   * @returns {Boolean} True if this instance was created by upsampling; otherwise, false.
   */
  GoogleEarthEnterpriseTerrainData.prototype.wasCreatedByUpsampling = function () {
    return this._createdByUpsampling;
  };

  var texCoordScratch0$1 = new Cartesian2();
  var texCoordScratch1$1 = new Cartesian2();
  var texCoordScratch2$1 = new Cartesian2();
  var barycentricCoordinateScratch$1 = new Cartesian3();

  function interpolateMeshHeight$2(terrainData, u, v) {
    var mesh = terrainData._mesh;
    var vertices = mesh.vertices;
    var encoding = mesh.encoding;
    var indices = mesh.indices;

    for (var i = 0, len = indices.length; i < len; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];

      var uv0 = encoding.decodeTextureCoordinates(vertices, i0, texCoordScratch0$1);
      var uv1 = encoding.decodeTextureCoordinates(vertices, i1, texCoordScratch1$1);
      var uv2 = encoding.decodeTextureCoordinates(vertices, i2, texCoordScratch2$1);

      var barycentric = Intersections2D.computeBarycentricCoordinates(
        u,
        v,
        uv0.x,
        uv0.y,
        uv1.x,
        uv1.y,
        uv2.x,
        uv2.y,
        barycentricCoordinateScratch$1
      );
      if (
        barycentric.x >= -1e-15 &&
        barycentric.y >= -1e-15 &&
        barycentric.z >= -1e-15
      ) {
        var h0 = encoding.decodeHeight(vertices, i0);
        var h1 = encoding.decodeHeight(vertices, i1);
        var h2 = encoding.decodeHeight(vertices, i2);
        return barycentric.x * h0 + barycentric.y * h1 + barycentric.z * h2;
      }
    }

    // Position does not lie in any triangle in this mesh.
    return undefined;
  }

  var sizeOfUint16 = Uint16Array.BYTES_PER_ELEMENT;
  var sizeOfUint32 = Uint32Array.BYTES_PER_ELEMENT;
  var sizeOfInt32 = Int32Array.BYTES_PER_ELEMENT;
  var sizeOfFloat = Float32Array.BYTES_PER_ELEMENT;
  var sizeOfDouble = Float64Array.BYTES_PER_ELEMENT;

  function interpolateHeight$2(terrainData, u, v, rectangle) {
    var buffer = terrainData._buffer;
    var quad = 0; // SW
    var uStart = 0.0;
    var vStart = 0.0;
    if (v > 0.5) {
      // Upper row
      if (u > 0.5) {
        // NE
        quad = 2;
        uStart = 0.5;
      } else {
        // NW
        quad = 3;
      }
      vStart = 0.5;
    } else if (u > 0.5) {
      // SE
      quad = 1;
      uStart = 0.5;
    }

    var dv = new DataView(buffer);
    var offset = 0;
    for (var q = 0; q < quad; ++q) {
      offset += dv.getUint32(offset, true);
      offset += sizeOfUint32;
    }
    offset += sizeOfUint32; // Skip length of quad
    offset += 2 * sizeOfDouble; // Skip origin

    // Read sizes
    var xSize = CesiumMath.toRadians(dv.getFloat64(offset, true) * 180.0);
    offset += sizeOfDouble;
    var ySize = CesiumMath.toRadians(dv.getFloat64(offset, true) * 180.0);
    offset += sizeOfDouble;

    // Samples per quad
    var xScale = rectangle.width / xSize / 2;
    var yScale = rectangle.height / ySize / 2;

    // Number of points
    var numPoints = dv.getInt32(offset, true);
    offset += sizeOfInt32;

    // Number of faces
    var numIndices = dv.getInt32(offset, true) * 3;
    offset += sizeOfInt32;

    offset += sizeOfInt32; // Skip Level

    var uBuffer = new Array(numPoints);
    var vBuffer = new Array(numPoints);
    var heights = new Array(numPoints);
    var i;
    for (i = 0; i < numPoints; ++i) {
      uBuffer[i] = uStart + dv.getUint8(offset++) * xScale;
      vBuffer[i] = vStart + dv.getUint8(offset++) * yScale;

      // Height is stored in units of (1/EarthRadius) or (1/6371010.0)
      heights[i] = dv.getFloat32(offset, true) * 6371010.0;
      offset += sizeOfFloat;
    }

    var indices = new Array(numIndices);
    for (i = 0; i < numIndices; ++i) {
      indices[i] = dv.getUint16(offset, true);
      offset += sizeOfUint16;
    }

    for (i = 0; i < numIndices; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];

      var u0 = uBuffer[i0];
      var u1 = uBuffer[i1];
      var u2 = uBuffer[i2];

      var v0 = vBuffer[i0];
      var v1 = vBuffer[i1];
      var v2 = vBuffer[i2];

      var barycentric = Intersections2D.computeBarycentricCoordinates(
        u,
        v,
        u0,
        v0,
        u1,
        v1,
        u2,
        v2,
        barycentricCoordinateScratch$1
      );
      if (
        barycentric.x >= -1e-15 &&
        barycentric.y >= -1e-15 &&
        barycentric.z >= -1e-15
      ) {
        return (
          barycentric.x * heights[i0] +
          barycentric.y * heights[i1] +
          barycentric.z * heights[i2]
        );
      }
    }

    // Position does not lie in any triangle in this mesh.
    return undefined;
  }

  var TerrainState = {
    UNKNOWN: 0,
    NONE: 1,
    SELF: 2,
    PARENT: 3,
  };

  var julianDateScratch$1 = new JulianDate();

  function TerrainCache() {
    this._terrainCache = {};
    this._lastTidy = JulianDate.now();
  }

  TerrainCache.prototype.add = function (quadKey, buffer) {
    this._terrainCache[quadKey] = {
      buffer: buffer,
      timestamp: JulianDate.now(),
    };
  };

  TerrainCache.prototype.get = function (quadKey) {
    var terrainCache = this._terrainCache;
    var result = terrainCache[quadKey];
    if (defined(result)) {
      delete this._terrainCache[quadKey];
      return result.buffer;
    }
  };

  TerrainCache.prototype.tidy = function () {
    JulianDate.now(julianDateScratch$1);
    if (JulianDate.secondsDifference(julianDateScratch$1, this._lastTidy) > 10) {
      var terrainCache = this._terrainCache;
      var keys = Object.keys(terrainCache);
      var count = keys.length;
      for (var i = 0; i < count; ++i) {
        var k = keys[i];
        var e = terrainCache[k];
        if (JulianDate.secondsDifference(julianDateScratch$1, e.timestamp) > 10) {
          delete terrainCache[k];
        }
      }

      JulianDate.clone(julianDateScratch$1, this._lastTidy);
    }
  };

  /**
   * Provides tiled terrain using the Google Earth Enterprise REST API.
   *
   * @alias GoogleEarthEnterpriseTerrainProvider
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String} options.url The url of the Google Earth Enterprise server hosting the imagery.
   * @param {GoogleEarthEnterpriseMetadata} options.metadata A metadata object that can be used to share metadata requests with a GoogleEarthEnterpriseImageryProvider.
   * @param {Ellipsoid} [options.ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
   *
   * @see GoogleEarthEnterpriseImageryProvider
   * @see CesiumTerrainProvider
   *
   * @example
   * var geeMetadata = new GoogleEarthEnterpriseMetadata('http://www.earthenterprise.org/3d');
   * var gee = new Cesium.GoogleEarthEnterpriseTerrainProvider({
   *     metadata : geeMetadata
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  function GoogleEarthEnterpriseTerrainProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!(defined(options.url) || defined(options.metadata))) {
      throw new DeveloperError("options.url or options.metadata is required.");
    }
    //>>includeEnd('debug');

    var metadata;
    if (defined(options.metadata)) {
      metadata = options.metadata;
    } else {
      var resource = Resource.createIfNeeded(options.url);
      metadata = new GoogleEarthEnterpriseMetadata(resource);
    }

    this._metadata = metadata;
    this._tilingScheme = new GeographicTilingScheme({
      numberOfLevelZeroTilesX: 2,
      numberOfLevelZeroTilesY: 2,
      rectangle: new Rectangle(
        -CesiumMath.PI,
        -CesiumMath.PI,
        CesiumMath.PI,
        CesiumMath.PI
      ),
      ellipsoid: options.ellipsoid,
    });

    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    // Pulled from Google's documentation
    this._levelZeroMaximumGeometricError = 40075.16;

    this._terrainCache = new TerrainCache();
    this._terrainPromises = {};
    this._terrainRequests = {};

    this._errorEvent = new Event();

    this._ready = false;
    var that = this;
    var metadataError;
    this._readyPromise = metadata.readyPromise
      .then(function (result) {
        if (!metadata.terrainPresent) {
          var e = new RuntimeError(
            "The server " + metadata.url + " doesn't have terrain"
          );
          metadataError = TileProviderError.handleError(
            metadataError,
            that,
            that._errorEvent,
            e.message,
            undefined,
            undefined,
            undefined,
            e
          );
          return when.reject(e);
        }

        TileProviderError.handleSuccess(metadataError);
        that._ready = result;
        return result;
      })
      .otherwise(function (e) {
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          e.message,
          undefined,
          undefined,
          undefined,
          e
        );
        return when.reject(e);
      });
  }

  Object.defineProperties(GoogleEarthEnterpriseTerrainProvider.prototype, {
    /**
     * Gets the name of the Google Earth Enterprise server url hosting the imagery.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._metadata.url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._metadata.proxy;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link GoogleEarthEnterpriseTerrainProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the credit to display when this terrain provider is active.  Typically this is used to credit
     * the source of the terrain.  This function should not be called before {@link GoogleEarthEnterpriseTerrainProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the provider includes a water mask.  The water mask
     * indicates which areas of the globe are water rather than land, so they can be rendered
     * as a reflective surface with animated waves.  This function should not be
     * called before {@link GoogleEarthEnterpriseTerrainProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Boolean}
     */
    hasWaterMask: {
      get: function () {
        return false;
      },
    },

    /**
     * Gets a value indicating whether or not the requested tiles include vertex normals.
     * This function should not be called before {@link GoogleEarthEnterpriseTerrainProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {Boolean}
     */
    hasVertexNormals: {
      get: function () {
        return false;
      },
    },

    /**
     * Gets an object that can be used to determine availability of terrain from this provider, such as
     * at points and in rectangles.  This function should not be called before
     * {@link GoogleEarthEnterpriseTerrainProvider#ready} returns true.  This property may be undefined if availability
     * information is not available.
     * @memberof GoogleEarthEnterpriseTerrainProvider.prototype
     * @type {TileAvailability}
     */
    availability: {
      get: function () {
        return undefined;
      },
    },
  });

  var taskProcessor$3 = new TaskProcessor(
    "decodeGoogleEarthEnterprisePacket",
    Number.POSITIVE_INFINITY
  );

  // If the tile has its own terrain, then you can just use its child bitmask. If it was requested using it's parent
  //  then you need to check all of its children to see if they have terrain.
  function computeChildMask(quadKey, info, metadata) {
    var childMask = info.getChildBitmask();
    if (info.terrainState === TerrainState.PARENT) {
      childMask = 0;
      for (var i = 0; i < 4; ++i) {
        var child = metadata.getTileInformationFromQuadKey(
          quadKey + i.toString()
        );
        if (defined(child) && child.hasTerrain()) {
          childMask |= 1 << i;
        }
      }
    }

    return childMask;
  }

  /**
   * Requests the geometry for a given tile.  This function should not be called before
   * {@link GoogleEarthEnterpriseTerrainProvider#ready} returns true.  The result must include terrain data and
   * may optionally include a water mask and an indication of which child tiles are available.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry.  If this method
   *          returns undefined instead of a promise, it is an indication that too many requests are already
   *          pending and the request will be retried later.
   *
   * @exception {DeveloperError} This function must not be called before {@link GoogleEarthEnterpriseTerrainProvider#ready}
   *            returns true.
   */
  GoogleEarthEnterpriseTerrainProvider.prototype.requestTileGeometry = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug)
    if (!this._ready) {
      throw new DeveloperError(
        "requestTileGeometry must not be called before the terrain provider is ready."
      );
    }
    //>>includeEnd('debug');

    var quadKey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
    var terrainCache = this._terrainCache;
    var metadata = this._metadata;
    var info = metadata.getTileInformationFromQuadKey(quadKey);

    // Check if this tile is even possibly available
    if (!defined(info)) {
      return when.reject(new RuntimeError("Terrain tile doesn't exist"));
    }

    var terrainState = info.terrainState;
    if (!defined(terrainState)) {
      // First time we have tried to load this tile, so set terrain state to UNKNOWN
      terrainState = info.terrainState = TerrainState.UNKNOWN;
    }

    // If its in the cache, return it
    var buffer = terrainCache.get(quadKey);
    if (defined(buffer)) {
      var credit = metadata.providers[info.terrainProvider];
      return when.resolve(
        new GoogleEarthEnterpriseTerrainData({
          buffer: buffer,
          childTileMask: computeChildMask(quadKey, info, metadata),
          credits: defined(credit) ? [credit] : undefined,
          negativeAltitudeExponentBias: metadata.negativeAltitudeExponentBias,
          negativeElevationThreshold: metadata.negativeAltitudeThreshold,
        })
      );
    }

    // Clean up the cache
    terrainCache.tidy();

    // We have a tile, check to see if no ancestors have terrain or that we know for sure it doesn't
    if (!info.ancestorHasTerrain) {
      // We haven't reached a level with terrain, so return the ellipsoid
      return when.resolve(
        new HeightmapTerrainData({
          buffer: new Uint8Array(16 * 16),
          width: 16,
          height: 16,
        })
      );
    } else if (terrainState === TerrainState.NONE) {
      // Already have info and there isn't any terrain here
      return when.reject(new RuntimeError("Terrain tile doesn't exist"));
    }

    // Figure out where we are getting the terrain and what version
    var parentInfo;
    var q = quadKey;
    var terrainVersion = -1;
    switch (terrainState) {
      case TerrainState.SELF: // We have terrain and have retrieved it before
        terrainVersion = info.terrainVersion;
        break;
      case TerrainState.PARENT: // We have terrain in our parent
        q = q.substring(0, q.length - 1);
        parentInfo = metadata.getTileInformationFromQuadKey(q);
        terrainVersion = parentInfo.terrainVersion;
        break;
      case TerrainState.UNKNOWN: // We haven't tried to retrieve terrain yet
        if (info.hasTerrain()) {
          terrainVersion = info.terrainVersion; // We should have terrain
        } else {
          q = q.substring(0, q.length - 1);
          parentInfo = metadata.getTileInformationFromQuadKey(q);
          if (defined(parentInfo) && parentInfo.hasTerrain()) {
            terrainVersion = parentInfo.terrainVersion; // Try checking in the parent
          }
        }
        break;
    }

    // We can't figure out where to get the terrain
    if (terrainVersion < 0) {
      return when.reject(new RuntimeError("Terrain tile doesn't exist"));
    }

    // Load that terrain
    var terrainPromises = this._terrainPromises;
    var terrainRequests = this._terrainRequests;
    var sharedPromise;
    var sharedRequest;
    if (defined(terrainPromises[q])) {
      // Already being loaded possibly from another child, so return existing promise
      sharedPromise = terrainPromises[q];
      sharedRequest = terrainRequests[q];
    } else {
      // Create new request for terrain
      sharedRequest = request;
      var requestPromise = buildTerrainResource(
        this,
        q,
        terrainVersion,
        sharedRequest
      ).fetchArrayBuffer();

      if (!defined(requestPromise)) {
        return undefined; // Throttled
      }

      sharedPromise = requestPromise.then(function (terrain) {
        if (defined(terrain)) {
          return taskProcessor$3
            .scheduleTask(
              {
                buffer: terrain,
                type: "Terrain",
                key: metadata.key,
              },
              [terrain]
            )
            .then(function (terrainTiles) {
              // Add requested tile and mark it as SELF
              var requestedInfo = metadata.getTileInformationFromQuadKey(q);
              requestedInfo.terrainState = TerrainState.SELF;
              terrainCache.add(q, terrainTiles[0]);
              var provider = requestedInfo.terrainProvider;

              // Add children to cache
              var count = terrainTiles.length - 1;
              for (var j = 0; j < count; ++j) {
                var childKey = q + j.toString();
                var child = metadata.getTileInformationFromQuadKey(childKey);
                if (defined(child)) {
                  terrainCache.add(childKey, terrainTiles[j + 1]);
                  child.terrainState = TerrainState.PARENT;
                  if (child.terrainProvider === 0) {
                    child.terrainProvider = provider;
                  }
                }
              }
            });
        }

        return when.reject(new RuntimeError("Failed to load terrain."));
      });

      terrainPromises[q] = sharedPromise; // Store promise without delete from terrainPromises
      terrainRequests[q] = sharedRequest;

      // Set promise so we remove from terrainPromises just one time
      sharedPromise = sharedPromise.always(function () {
        delete terrainPromises[q];
        delete terrainRequests[q];
      });
    }

    return sharedPromise
      .then(function () {
        var buffer = terrainCache.get(quadKey);
        if (defined(buffer)) {
          var credit = metadata.providers[info.terrainProvider];
          return new GoogleEarthEnterpriseTerrainData({
            buffer: buffer,
            childTileMask: computeChildMask(quadKey, info, metadata),
            credits: defined(credit) ? [credit] : undefined,
            negativeAltitudeExponentBias: metadata.negativeAltitudeExponentBias,
            negativeElevationThreshold: metadata.negativeAltitudeThreshold,
          });
        }

        return when.reject(new RuntimeError("Failed to load terrain."));
      })
      .otherwise(function (error) {
        if (sharedRequest.state === RequestState$1.CANCELLED) {
          request.state = sharedRequest.state;
          return when.reject(error);
        }
        info.terrainState = TerrainState.NONE;
        return when.reject(error);
      });
  };

  /**
   * Gets the maximum geometric error allowed in a tile at a given level.
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error.
   */
  GoogleEarthEnterpriseTerrainProvider.prototype.getLevelMaximumGeometricError = function (
    level
  ) {
    return this._levelZeroMaximumGeometricError / (1 << level);
  };

  /**
   * Determines whether data for a tile is available to be loaded.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {Boolean} Undefined if not supported, otherwise true or false.
   */
  GoogleEarthEnterpriseTerrainProvider.prototype.getTileDataAvailable = function (
    x,
    y,
    level
  ) {
    var metadata = this._metadata;
    var quadKey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);

    var info = metadata.getTileInformation(x, y, level);
    if (info === null) {
      return false;
    }

    if (defined(info)) {
      if (!info.ancestorHasTerrain) {
        return true; // We'll just return the ellipsoid
      }

      var terrainState = info.terrainState;
      if (terrainState === TerrainState.NONE) {
        return false; // Terrain is not available
      }

      if (!defined(terrainState) || terrainState === TerrainState.UNKNOWN) {
        info.terrainState = TerrainState.UNKNOWN;
        if (!info.hasTerrain()) {
          quadKey = quadKey.substring(0, quadKey.length - 1);
          var parentInfo = metadata.getTileInformationFromQuadKey(quadKey);
          if (!defined(parentInfo) || !parentInfo.hasTerrain()) {
            return false;
          }
        }
      }

      return true;
    }

    if (metadata.isValid(quadKey)) {
      // We will need this tile, so request metadata and return false for now
      var request = new Request({
        throttle: true,
        throttleByServer: true,
        type: RequestType$1.TERRAIN,
      });
      metadata.populateSubtree(x, y, level, request);
    }
    return false;
  };

  /**
   * Makes sure we load availability data for a tile
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {undefined|Promise<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
   */
  GoogleEarthEnterpriseTerrainProvider.prototype.loadTileDataAvailability = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  //
  // Functions to handle imagery packets
  //
  function buildTerrainResource(terrainProvider, quadKey, version, request) {
    version = defined(version) && version > 0 ? version : 1;
    return terrainProvider._metadata.resource.getDerivedResource({
      url: "flatfile?f1c-0" + quadKey + "-t." + version.toString(),
      request: request,
    });
  }

  var PROJECTIONS = [GeographicProjection, WebMercatorProjection];
  var PROJECTION_COUNT = PROJECTIONS.length;

  var MITER_BREAK_SMALL = Math.cos(CesiumMath.toRadians(30.0));
  var MITER_BREAK_LARGE = Math.cos(CesiumMath.toRadians(150.0));

  // Initial heights for constructing the wall.
  // Keeping WALL_INITIAL_MIN_HEIGHT near the ellipsoid surface helps
  // prevent precision problems with planes in the shader.
  // Putting the start point of a plane at ApproximateTerrainHeights._defaultMinTerrainHeight,
  // which is a highly conservative bound, usually puts the plane origin several thousands
  // of meters away from the actual terrain, causing floating point problems when checking
  // fragments on terrain against the plane.
  // Ellipsoid height is generally much closer.
  // The initial max height is arbitrary.
  // Both heights are corrected using ApproximateTerrainHeights for computing the actual volume geometry.
  var WALL_INITIAL_MIN_HEIGHT = 0.0;
  var WALL_INITIAL_MAX_HEIGHT = 1000.0;

  /**
   * A description of a polyline on terrain or 3D Tiles. Only to be used with {@link GroundPolylinePrimitive}.
   *
   * @alias GroundPolylineGeometry
   * @constructor
   *
   * @param {Object} options Options with the following properties:
   * @param {Cartesian3[]} options.positions An array of {@link Cartesian3} defining the polyline's points. Heights above the ellipsoid will be ignored.
   * @param {Number} [options.width=1.0] The screen space width in pixels.
   * @param {Number} [options.granularity=9999.0] The distance interval in meters used for interpolating options.points. Defaults to 9999.0 meters. Zero indicates no interpolation.
   * @param {Boolean} [options.loop=false] Whether during geometry creation a line segment will be added between the last and first line positions to make this Polyline a loop.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of line the polyline segments must follow. Valid options are {@link ArcType.GEODESIC} and {@link ArcType.RHUMB}.
   *
   * @exception {DeveloperError} At least two positions are required.
   *
   * @see GroundPolylinePrimitive
   *
   * @example
   * var positions = Cesium.Cartesian3.fromDegreesArray([
   *   -112.1340164450331, 36.05494287836128,
   *   -112.08821010582645, 36.097804071380715,
   *   -112.13296079730024, 36.168769146801104
   * ]);
   *
   * var geometry = new Cesium.GroundPolylineGeometry({
   *   positions : positions
   * });
   */
  function GroundPolylineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions) || positions.length < 2) {
      throw new DeveloperError("At least two positions are required.");
    }
    if (
      defined(options.arcType) &&
      options.arcType !== ArcType$1.GEODESIC &&
      options.arcType !== ArcType$1.RHUMB
    ) {
      throw new DeveloperError(
        "Valid options for arcType are ArcType.GEODESIC and ArcType.RHUMB."
      );
    }
    //>>includeEnd('debug');

    /**
     * The screen space width in pixels.
     * @type {Number}
     */
    this.width = defaultValue(options.width, 1.0); // Doesn't get packed, not necessary for computing geometry.

    this._positions = positions;

    /**
     * The distance interval used for interpolating options.points. Zero indicates no interpolation.
     * Default of 9999.0 allows centimeter accuracy with 32 bit floating point.
     * @type {Boolean}
     * @default 9999.0
     */
    this.granularity = defaultValue(options.granularity, 9999.0);

    /**
     * Whether during geometry creation a line segment will be added between the last and first line positions to make this Polyline a loop.
     * If the geometry has two positions this parameter will be ignored.
     * @type {Boolean}
     * @default false
     */
    this.loop = defaultValue(options.loop, false);

    /**
     * The type of path the polyline must follow. Valid options are {@link ArcType.GEODESIC} and {@link ArcType.RHUMB}.
     * @type {ArcType}
     * @default ArcType.GEODESIC
     */
    this.arcType = defaultValue(options.arcType, ArcType$1.GEODESIC);

    this._ellipsoid = Ellipsoid.WGS84;

    // MapProjections can't be packed, so store the index to a known MapProjection.
    this._projectionIndex = 0;
    this._workerName = "createGroundPolylineGeometry";

    // Used by GroundPolylinePrimitive to signal worker that scenemode is 3D only.
    this._scene3DOnly = false;
  }

  Object.defineProperties(GroundPolylineGeometry.prototype, {
    /**
     * The number of elements used to pack the object into an array.
     * @memberof GroundPolylineGeometry.prototype
     * @type {Number}
     * @readonly
     * @private
     */
    packedLength: {
      get: function () {
        return (
          1.0 +
          this._positions.length * 3 +
          1.0 +
          1.0 +
          1.0 +
          Ellipsoid.packedLength +
          1.0 +
          1.0
        );
      },
    },
  });

  /**
   * Set the GroundPolylineGeometry's projection and ellipsoid.
   * Used by GroundPolylinePrimitive to signal scene information to the geometry for generating 2D attributes.
   *
   * @param {GroundPolylineGeometry} groundPolylineGeometry GroundPolylinGeometry describing a polyline on terrain or 3D Tiles.
   * @param {Projection} mapProjection A MapProjection used for projecting cartographic coordinates to 2D.
   * @private
   */
  GroundPolylineGeometry.setProjectionAndEllipsoid = function (
    groundPolylineGeometry,
    mapProjection
  ) {
    var projectionIndex = 0;
    for (var i = 0; i < PROJECTION_COUNT; i++) {
      if (mapProjection instanceof PROJECTIONS[i]) {
        projectionIndex = i;
        break;
      }
    }

    groundPolylineGeometry._projectionIndex = projectionIndex;
    groundPolylineGeometry._ellipsoid = mapProjection.ellipsoid;
  };

  var cart3Scratch1 = new Cartesian3();
  var cart3Scratch2 = new Cartesian3();
  var cart3Scratch3 = new Cartesian3();
  function computeRightNormal(start, end, maxHeight, ellipsoid, result) {
    var startBottom = getPosition(ellipsoid, start, 0.0, cart3Scratch1);
    var startTop = getPosition(ellipsoid, start, maxHeight, cart3Scratch2);
    var endBottom = getPosition(ellipsoid, end, 0.0, cart3Scratch3);

    var up = direction(startTop, startBottom, cart3Scratch2);
    var forward = direction(endBottom, startBottom, cart3Scratch3);

    Cartesian3.cross(forward, up, result);
    return Cartesian3.normalize(result, result);
  }

  var interpolatedCartographicScratch = new Cartographic();
  var interpolatedBottomScratch = new Cartesian3();
  var interpolatedTopScratch = new Cartesian3();
  var interpolatedNormalScratch = new Cartesian3();
  function interpolateSegment(
    start,
    end,
    minHeight,
    maxHeight,
    granularity,
    arcType,
    ellipsoid,
    normalsArray,
    bottomPositionsArray,
    topPositionsArray,
    cartographicsArray
  ) {
    if (granularity === 0.0) {
      return;
    }

    var ellipsoidLine;
    if (arcType === ArcType$1.GEODESIC) {
      ellipsoidLine = new EllipsoidGeodesic(start, end, ellipsoid);
    } else if (arcType === ArcType$1.RHUMB) {
      ellipsoidLine = new EllipsoidRhumbLine(start, end, ellipsoid);
    }

    var surfaceDistance = ellipsoidLine.surfaceDistance;
    if (surfaceDistance < granularity) {
      return;
    }

    // Compute rightwards normal applicable at all interpolated points
    var interpolatedNormal = computeRightNormal(
      start,
      end,
      maxHeight,
      ellipsoid,
      interpolatedNormalScratch
    );

    var segments = Math.ceil(surfaceDistance / granularity);
    var interpointDistance = surfaceDistance / segments;
    var distanceFromStart = interpointDistance;
    var pointsToAdd = segments - 1;
    var packIndex = normalsArray.length;
    for (var i = 0; i < pointsToAdd; i++) {
      var interpolatedCartographic = ellipsoidLine.interpolateUsingSurfaceDistance(
        distanceFromStart,
        interpolatedCartographicScratch
      );
      var interpolatedBottom = getPosition(
        ellipsoid,
        interpolatedCartographic,
        minHeight,
        interpolatedBottomScratch
      );
      var interpolatedTop = getPosition(
        ellipsoid,
        interpolatedCartographic,
        maxHeight,
        interpolatedTopScratch
      );

      Cartesian3.pack(interpolatedNormal, normalsArray, packIndex);
      Cartesian3.pack(interpolatedBottom, bottomPositionsArray, packIndex);
      Cartesian3.pack(interpolatedTop, topPositionsArray, packIndex);
      cartographicsArray.push(interpolatedCartographic.latitude);
      cartographicsArray.push(interpolatedCartographic.longitude);

      packIndex += 3;
      distanceFromStart += interpointDistance;
    }
  }

  var heightlessCartographicScratch = new Cartographic();
  function getPosition(ellipsoid, cartographic, height, result) {
    Cartographic.clone(cartographic, heightlessCartographicScratch);
    heightlessCartographicScratch.height = height;
    return Cartographic.toCartesian(
      heightlessCartographicScratch,
      ellipsoid,
      result
    );
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PolygonGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  GroundPolylineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    var index = defaultValue(startingIndex, 0);

    var positions = value._positions;
    var positionsLength = positions.length;

    array[index++] = positionsLength;

    for (var i = 0; i < positionsLength; ++i) {
      var cartesian = positions[i];
      Cartesian3.pack(cartesian, array, index);
      index += 3;
    }

    array[index++] = value.granularity;
    array[index++] = value.loop ? 1.0 : 0.0;
    array[index++] = value.arcType;

    Ellipsoid.pack(value._ellipsoid, array, index);
    index += Ellipsoid.packedLength;

    array[index++] = value._projectionIndex;
    array[index++] = value._scene3DOnly ? 1.0 : 0.0;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PolygonGeometry} [result] The object into which to store the result.
   */
  GroundPolylineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    var index = defaultValue(startingIndex, 0);
    var positionsLength = array[index++];
    var positions = new Array(positionsLength);

    for (var i = 0; i < positionsLength; i++) {
      positions[i] = Cartesian3.unpack(array, index);
      index += 3;
    }

    var granularity = array[index++];
    var loop = array[index++] === 1.0;
    var arcType = array[index++];

    var ellipsoid = Ellipsoid.unpack(array, index);
    index += Ellipsoid.packedLength;

    var projectionIndex = array[index++];
    var scene3DOnly = array[index++] === 1.0;

    if (!defined(result)) {
      result = new GroundPolylineGeometry({
        positions: positions,
      });
    }

    result._positions = positions;
    result.granularity = granularity;
    result.loop = loop;
    result.arcType = arcType;
    result._ellipsoid = ellipsoid;
    result._projectionIndex = projectionIndex;
    result._scene3DOnly = scene3DOnly;

    return result;
  };

  function direction(target, origin, result) {
    Cartesian3.subtract(target, origin, result);
    Cartesian3.normalize(result, result);
    return result;
  }

  function tangentDirection(target, origin, up, result) {
    result = direction(target, origin, result);

    // orthogonalize
    result = Cartesian3.cross(result, up, result);
    result = Cartesian3.normalize(result, result);
    result = Cartesian3.cross(up, result, result);
    return result;
  }

  var toPreviousScratch = new Cartesian3();
  var toNextScratch = new Cartesian3();
  var forwardScratch = new Cartesian3();
  var vertexUpScratch = new Cartesian3();
  var cosine90 = 0.0;
  var cosine180 = -1.0;
  function computeVertexMiterNormal(
    previousBottom,
    vertexBottom,
    vertexTop,
    nextBottom,
    result
  ) {
    var up = direction(vertexTop, vertexBottom, vertexUpScratch);

    // Compute vectors pointing towards neighboring points but tangent to this point on the ellipsoid
    var toPrevious = tangentDirection(
      previousBottom,
      vertexBottom,
      up,
      toPreviousScratch
    );
    var toNext = tangentDirection(nextBottom, vertexBottom, up, toNextScratch);

    // Check if tangents are almost opposite - if so, no need to miter.
    if (
      CesiumMath.equalsEpsilon(
        Cartesian3.dot(toPrevious, toNext),
        cosine180,
        CesiumMath.EPSILON5
      )
    ) {
      result = Cartesian3.cross(up, toPrevious, result);
      result = Cartesian3.normalize(result, result);
      return result;
    }

    // Average directions to previous and to next in the plane of Up
    result = Cartesian3.add(toNext, toPrevious, result);
    result = Cartesian3.normalize(result, result);

    // Flip the normal if it isn't pointing roughly bound right (aka if forward is pointing more "backwards")
    var forward = Cartesian3.cross(up, result, forwardScratch);
    if (Cartesian3.dot(toNext, forward) < cosine90) {
      result = Cartesian3.negate(result, result);
    }

    return result;
  }

  var XZ_PLANE = Plane.fromPointNormal(Cartesian3.ZERO, Cartesian3.UNIT_Y);

  var previousBottomScratch = new Cartesian3();
  var vertexBottomScratch = new Cartesian3();
  var vertexTopScratch = new Cartesian3();
  var nextBottomScratch = new Cartesian3();
  var vertexNormalScratch = new Cartesian3();
  var intersectionScratch = new Cartesian3();
  var cartographicScratch0 = new Cartographic();
  var cartographicScratch1 = new Cartographic();
  var cartographicIntersectionScratch = new Cartographic();
  /**
   * Computes shadow volumes for the ground polyline, consisting of its vertices, indices, and a bounding sphere.
   * Vertices are "fat," packing all the data needed in each volume to describe a line on terrain or 3D Tiles.
   * Should not be called independent of {@link GroundPolylinePrimitive}.
   *
   * @param {GroundPolylineGeometry} groundPolylineGeometry
   * @private
   */
  GroundPolylineGeometry.createGeometry = function (groundPolylineGeometry) {
    var compute2dAttributes = !groundPolylineGeometry._scene3DOnly;
    var loop = groundPolylineGeometry.loop;
    var ellipsoid = groundPolylineGeometry._ellipsoid;
    var granularity = groundPolylineGeometry.granularity;
    var arcType = groundPolylineGeometry.arcType;
    var projection = new PROJECTIONS[groundPolylineGeometry._projectionIndex](
      ellipsoid
    );

    var minHeight = WALL_INITIAL_MIN_HEIGHT;
    var maxHeight = WALL_INITIAL_MAX_HEIGHT;

    var index;
    var i;

    var positions = groundPolylineGeometry._positions;
    var positionsLength = positions.length;

    if (positionsLength === 2) {
      loop = false;
    }

    // Split positions across the IDL and the Prime Meridian as well.
    // Split across prime meridian because very large geometries crossing the Prime Meridian but not the IDL
    // may get split by the plane of IDL + Prime Meridian.
    var p0;
    var p1;
    var c0;
    var c1;
    var rhumbLine = new EllipsoidRhumbLine(undefined, undefined, ellipsoid);
    var intersection;
    var intersectionCartographic;
    var intersectionLongitude;
    var splitPositions = [positions[0]];
    for (i = 0; i < positionsLength - 1; i++) {
      p0 = positions[i];
      p1 = positions[i + 1];
      intersection = IntersectionTests.lineSegmentPlane(
        p0,
        p1,
        XZ_PLANE,
        intersectionScratch
      );
      if (
        defined(intersection) &&
        !Cartesian3.equalsEpsilon(intersection, p0, CesiumMath.EPSILON7) &&
        !Cartesian3.equalsEpsilon(intersection, p1, CesiumMath.EPSILON7)
      ) {
        if (groundPolylineGeometry.arcType === ArcType$1.GEODESIC) {
          splitPositions.push(Cartesian3.clone(intersection));
        } else if (groundPolylineGeometry.arcType === ArcType$1.RHUMB) {
          intersectionLongitude = ellipsoid.cartesianToCartographic(
            intersection,
            cartographicScratch0
          ).longitude;
          c0 = ellipsoid.cartesianToCartographic(p0, cartographicScratch0);
          c1 = ellipsoid.cartesianToCartographic(p1, cartographicScratch1);
          rhumbLine.setEndPoints(c0, c1);
          intersectionCartographic = rhumbLine.findIntersectionWithLongitude(
            intersectionLongitude,
            cartographicIntersectionScratch
          );
          intersection = ellipsoid.cartographicToCartesian(
            intersectionCartographic,
            intersectionScratch
          );
          if (
            defined(intersection) &&
            !Cartesian3.equalsEpsilon(intersection, p0, CesiumMath.EPSILON7) &&
            !Cartesian3.equalsEpsilon(intersection, p1, CesiumMath.EPSILON7)
          ) {
            splitPositions.push(Cartesian3.clone(intersection));
          }
        }
      }
      splitPositions.push(p1);
    }

    if (loop) {
      p0 = positions[positionsLength - 1];
      p1 = positions[0];
      intersection = IntersectionTests.lineSegmentPlane(
        p0,
        p1,
        XZ_PLANE,
        intersectionScratch
      );
      if (
        defined(intersection) &&
        !Cartesian3.equalsEpsilon(intersection, p0, CesiumMath.EPSILON7) &&
        !Cartesian3.equalsEpsilon(intersection, p1, CesiumMath.EPSILON7)
      ) {
        if (groundPolylineGeometry.arcType === ArcType$1.GEODESIC) {
          splitPositions.push(Cartesian3.clone(intersection));
        } else if (groundPolylineGeometry.arcType === ArcType$1.RHUMB) {
          intersectionLongitude = ellipsoid.cartesianToCartographic(
            intersection,
            cartographicScratch0
          ).longitude;
          c0 = ellipsoid.cartesianToCartographic(p0, cartographicScratch0);
          c1 = ellipsoid.cartesianToCartographic(p1, cartographicScratch1);
          rhumbLine.setEndPoints(c0, c1);
          intersectionCartographic = rhumbLine.findIntersectionWithLongitude(
            intersectionLongitude,
            cartographicIntersectionScratch
          );
          intersection = ellipsoid.cartographicToCartesian(
            intersectionCartographic,
            intersectionScratch
          );
          if (
            defined(intersection) &&
            !Cartesian3.equalsEpsilon(intersection, p0, CesiumMath.EPSILON7) &&
            !Cartesian3.equalsEpsilon(intersection, p1, CesiumMath.EPSILON7)
          ) {
            splitPositions.push(Cartesian3.clone(intersection));
          }
        }
      }
    }
    var cartographicsLength = splitPositions.length;

    var cartographics = new Array(cartographicsLength);
    for (i = 0; i < cartographicsLength; i++) {
      var cartographic = Cartographic.fromCartesian(splitPositions[i], ellipsoid);
      cartographic.height = 0.0;
      cartographics[i] = cartographic;
    }

    cartographics = arrayRemoveDuplicates(
      cartographics,
      Cartographic.equalsEpsilon
    );
    cartographicsLength = cartographics.length;

    if (cartographicsLength < 2) {
      return undefined;
    }

    /**** Build heap-side arrays for positions, interpolated cartographics, and normals from which to compute vertices ****/
    // We build a "wall" and then decompose it into separately connected component "volumes" because we need a lot
    // of information about the wall. Also, this simplifies interpolation.
    // Convention: "next" and "end" are locally forward to each segment of the wall,
    // and we are computing normals pointing towards the local right side of the vertices in each segment.
    var cartographicsArray = [];
    var normalsArray = [];
    var bottomPositionsArray = [];
    var topPositionsArray = [];

    var previousBottom = previousBottomScratch;
    var vertexBottom = vertexBottomScratch;
    var vertexTop = vertexTopScratch;
    var nextBottom = nextBottomScratch;
    var vertexNormal = vertexNormalScratch;

    // First point - either loop or attach a "perpendicular" normal
    var startCartographic = cartographics[0];
    var nextCartographic = cartographics[1];

    var prestartCartographic = cartographics[cartographicsLength - 1];
    previousBottom = getPosition(
      ellipsoid,
      prestartCartographic,
      minHeight,
      previousBottom
    );
    nextBottom = getPosition(ellipsoid, nextCartographic, minHeight, nextBottom);
    vertexBottom = getPosition(
      ellipsoid,
      startCartographic,
      minHeight,
      vertexBottom
    );
    vertexTop = getPosition(ellipsoid, startCartographic, maxHeight, vertexTop);

    if (loop) {
      vertexNormal = computeVertexMiterNormal(
        previousBottom,
        vertexBottom,
        vertexTop,
        nextBottom,
        vertexNormal
      );
    } else {
      vertexNormal = computeRightNormal(
        startCartographic,
        nextCartographic,
        maxHeight,
        ellipsoid,
        vertexNormal
      );
    }

    Cartesian3.pack(vertexNormal, normalsArray, 0);
    Cartesian3.pack(vertexBottom, bottomPositionsArray, 0);
    Cartesian3.pack(vertexTop, topPositionsArray, 0);
    cartographicsArray.push(startCartographic.latitude);
    cartographicsArray.push(startCartographic.longitude);

    interpolateSegment(
      startCartographic,
      nextCartographic,
      minHeight,
      maxHeight,
      granularity,
      arcType,
      ellipsoid,
      normalsArray,
      bottomPositionsArray,
      topPositionsArray,
      cartographicsArray
    );

    // All inbetween points
    for (i = 1; i < cartographicsLength - 1; ++i) {
      previousBottom = Cartesian3.clone(vertexBottom, previousBottom);
      vertexBottom = Cartesian3.clone(nextBottom, vertexBottom);
      var vertexCartographic = cartographics[i];
      getPosition(ellipsoid, vertexCartographic, maxHeight, vertexTop);
      getPosition(ellipsoid, cartographics[i + 1], minHeight, nextBottom);

      computeVertexMiterNormal(
        previousBottom,
        vertexBottom,
        vertexTop,
        nextBottom,
        vertexNormal
      );

      index = normalsArray.length;
      Cartesian3.pack(vertexNormal, normalsArray, index);
      Cartesian3.pack(vertexBottom, bottomPositionsArray, index);
      Cartesian3.pack(vertexTop, topPositionsArray, index);
      cartographicsArray.push(vertexCartographic.latitude);
      cartographicsArray.push(vertexCartographic.longitude);

      interpolateSegment(
        cartographics[i],
        cartographics[i + 1],
        minHeight,
        maxHeight,
        granularity,
        arcType,
        ellipsoid,
        normalsArray,
        bottomPositionsArray,
        topPositionsArray,
        cartographicsArray
      );
    }

    // Last point - either loop or attach a normal "perpendicular" to the wall.
    var endCartographic = cartographics[cartographicsLength - 1];
    var preEndCartographic = cartographics[cartographicsLength - 2];

    vertexBottom = getPosition(
      ellipsoid,
      endCartographic,
      minHeight,
      vertexBottom
    );
    vertexTop = getPosition(ellipsoid, endCartographic, maxHeight, vertexTop);

    if (loop) {
      var postEndCartographic = cartographics[0];
      previousBottom = getPosition(
        ellipsoid,
        preEndCartographic,
        minHeight,
        previousBottom
      );
      nextBottom = getPosition(
        ellipsoid,
        postEndCartographic,
        minHeight,
        nextBottom
      );

      vertexNormal = computeVertexMiterNormal(
        previousBottom,
        vertexBottom,
        vertexTop,
        nextBottom,
        vertexNormal
      );
    } else {
      vertexNormal = computeRightNormal(
        preEndCartographic,
        endCartographic,
        maxHeight,
        ellipsoid,
        vertexNormal
      );
    }

    index = normalsArray.length;
    Cartesian3.pack(vertexNormal, normalsArray, index);
    Cartesian3.pack(vertexBottom, bottomPositionsArray, index);
    Cartesian3.pack(vertexTop, topPositionsArray, index);
    cartographicsArray.push(endCartographic.latitude);
    cartographicsArray.push(endCartographic.longitude);

    if (loop) {
      interpolateSegment(
        endCartographic,
        startCartographic,
        minHeight,
        maxHeight,
        granularity,
        arcType,
        ellipsoid,
        normalsArray,
        bottomPositionsArray,
        topPositionsArray,
        cartographicsArray
      );
      index = normalsArray.length;
      for (i = 0; i < 3; ++i) {
        normalsArray[index + i] = normalsArray[i];
        bottomPositionsArray[index + i] = bottomPositionsArray[i];
        topPositionsArray[index + i] = topPositionsArray[i];
      }
      cartographicsArray.push(startCartographic.latitude);
      cartographicsArray.push(startCartographic.longitude);
    }

    return generateGeometryAttributes(
      loop,
      projection,
      bottomPositionsArray,
      topPositionsArray,
      normalsArray,
      cartographicsArray,
      compute2dAttributes
    );
  };

  // If the end normal angle is too steep compared to the direction of the line segment,
  // "break" the miter by rotating the normal 90 degrees around the "up" direction at the point
  // For ultra precision we would want to project into a plane, but in practice this is sufficient.
  var lineDirectionScratch = new Cartesian3();
  var matrix3Scratch = new Matrix3();
  var quaternionScratch$2 = new Quaternion();
  function breakMiter(endGeometryNormal, startBottom, endBottom, endTop) {
    var lineDirection = direction(endBottom, startBottom, lineDirectionScratch);

    var dot = Cartesian3.dot(lineDirection, endGeometryNormal);
    if (dot > MITER_BREAK_SMALL || dot < MITER_BREAK_LARGE) {
      var vertexUp = direction(endTop, endBottom, vertexUpScratch);
      var angle =
        dot < MITER_BREAK_LARGE
          ? CesiumMath.PI_OVER_TWO
          : -CesiumMath.PI_OVER_TWO;
      var quaternion = Quaternion.fromAxisAngle(
        vertexUp,
        angle,
        quaternionScratch$2
      );
      var rotationMatrix = Matrix3.fromQuaternion(quaternion, matrix3Scratch);
      Matrix3.multiplyByVector(
        rotationMatrix,
        endGeometryNormal,
        endGeometryNormal
      );
      return true;
    }
    return false;
  }

  var endPosCartographicScratch = new Cartographic();
  var normalStartpointScratch = new Cartesian3();
  var normalEndpointScratch = new Cartesian3();
  function projectNormal(
    projection,
    cartographic,
    normal,
    projectedPosition,
    result
  ) {
    var position = Cartographic.toCartesian(
      cartographic,
      projection._ellipsoid,
      normalStartpointScratch
    );
    var normalEndpoint = Cartesian3.add(position, normal, normalEndpointScratch);
    var flipNormal = false;

    var ellipsoid = projection._ellipsoid;
    var normalEndpointCartographic = ellipsoid.cartesianToCartographic(
      normalEndpoint,
      endPosCartographicScratch
    );
    // If normal crosses the IDL, go the other way and flip the result.
    // In practice this almost never happens because the cartographic start
    // and end points of each segment are "nudged" to be on the same side
    // of the IDL and slightly away from the IDL.
    if (
      Math.abs(cartographic.longitude - normalEndpointCartographic.longitude) >
      CesiumMath.PI_OVER_TWO
    ) {
      flipNormal = true;
      normalEndpoint = Cartesian3.subtract(
        position,
        normal,
        normalEndpointScratch
      );
      normalEndpointCartographic = ellipsoid.cartesianToCartographic(
        normalEndpoint,
        endPosCartographicScratch
      );
    }

    normalEndpointCartographic.height = 0.0;
    var normalEndpointProjected = projection.project(
      normalEndpointCartographic,
      result
    );
    result = Cartesian3.subtract(
      normalEndpointProjected,
      projectedPosition,
      result
    );
    result.z = 0.0;
    result = Cartesian3.normalize(result, result);
    if (flipNormal) {
      Cartesian3.negate(result, result);
    }
    return result;
  }

  var adjustHeightNormalScratch = new Cartesian3();
  var adjustHeightOffsetScratch = new Cartesian3();
  function adjustHeights(
    bottom,
    top,
    minHeight,
    maxHeight,
    adjustHeightBottom,
    adjustHeightTop
  ) {
    // bottom and top should be at WALL_INITIAL_MIN_HEIGHT and WALL_INITIAL_MAX_HEIGHT, respectively
    var adjustHeightNormal = Cartesian3.subtract(
      top,
      bottom,
      adjustHeightNormalScratch
    );
    Cartesian3.normalize(adjustHeightNormal, adjustHeightNormal);

    var distanceForBottom = minHeight - WALL_INITIAL_MIN_HEIGHT;
    var adjustHeightOffset = Cartesian3.multiplyByScalar(
      adjustHeightNormal,
      distanceForBottom,
      adjustHeightOffsetScratch
    );
    Cartesian3.add(bottom, adjustHeightOffset, adjustHeightBottom);

    var distanceForTop = maxHeight - WALL_INITIAL_MAX_HEIGHT;
    adjustHeightOffset = Cartesian3.multiplyByScalar(
      adjustHeightNormal,
      distanceForTop,
      adjustHeightOffsetScratch
    );
    Cartesian3.add(top, adjustHeightOffset, adjustHeightTop);
  }

  var nudgeDirectionScratch = new Cartesian3();
  function nudgeXZ(start, end) {
    var startToXZdistance = Plane.getPointDistance(XZ_PLANE, start);
    var endToXZdistance = Plane.getPointDistance(XZ_PLANE, end);
    var offset = nudgeDirectionScratch;
    // Larger epsilon than what's used in GeometryPipeline, a centimeter in world space
    if (CesiumMath.equalsEpsilon(startToXZdistance, 0.0, CesiumMath.EPSILON2)) {
      offset = direction(end, start, offset);
      Cartesian3.multiplyByScalar(offset, CesiumMath.EPSILON2, offset);
      Cartesian3.add(start, offset, start);
    } else if (
      CesiumMath.equalsEpsilon(endToXZdistance, 0.0, CesiumMath.EPSILON2)
    ) {
      offset = direction(start, end, offset);
      Cartesian3.multiplyByScalar(offset, CesiumMath.EPSILON2, offset);
      Cartesian3.add(end, offset, end);
    }
  }

  // "Nudge" cartographic coordinates so start and end are on the same side of the IDL.
  // Nudge amounts are tiny, basically just an IDL flip.
  // Only used for 2D/CV.
  function nudgeCartographic(start, end) {
    var absStartLon = Math.abs(start.longitude);
    var absEndLon = Math.abs(end.longitude);
    if (
      CesiumMath.equalsEpsilon(absStartLon, CesiumMath.PI, CesiumMath.EPSILON11)
    ) {
      var endSign = CesiumMath.sign(end.longitude);
      start.longitude = endSign * (absStartLon - CesiumMath.EPSILON11);
      return 1;
    } else if (
      CesiumMath.equalsEpsilon(absEndLon, CesiumMath.PI, CesiumMath.EPSILON11)
    ) {
      var startSign = CesiumMath.sign(start.longitude);
      end.longitude = startSign * (absEndLon - CesiumMath.EPSILON11);
      return 2;
    }
    return 0;
  }

  var startCartographicScratch = new Cartographic();
  var endCartographicScratch = new Cartographic();

  var segmentStartTopScratch = new Cartesian3();
  var segmentEndTopScratch = new Cartesian3();
  var segmentStartBottomScratch = new Cartesian3();
  var segmentEndBottomScratch = new Cartesian3();
  var segmentStartNormalScratch = new Cartesian3();
  var segmentEndNormalScratch = new Cartesian3();

  var getHeightCartographics = [startCartographicScratch, endCartographicScratch];
  var getHeightRectangleScratch = new Rectangle();

  var adjustHeightStartTopScratch = new Cartesian3();
  var adjustHeightEndTopScratch = new Cartesian3();
  var adjustHeightStartBottomScratch = new Cartesian3();
  var adjustHeightEndBottomScratch = new Cartesian3();

  var segmentStart2DScratch = new Cartesian3();
  var segmentEnd2DScratch = new Cartesian3();
  var segmentStartNormal2DScratch = new Cartesian3();
  var segmentEndNormal2DScratch = new Cartesian3();

  var offsetScratch$1 = new Cartesian3();
  var startUpScratch = new Cartesian3();
  var endUpScratch = new Cartesian3();
  var rightScratch$1 = new Cartesian3();
  var startPlaneNormalScratch = new Cartesian3();
  var endPlaneNormalScratch = new Cartesian3();
  var encodeScratch = new EncodedCartesian3();

  var encodeScratch2D = new EncodedCartesian3();
  var forwardOffset2DScratch = new Cartesian3();
  var right2DScratch = new Cartesian3();

  var normalNudgeScratch = new Cartesian3();

  var scratchBoundingSpheres = [new BoundingSphere(), new BoundingSphere()];

  // Winding order is reversed so each segment's volume is inside-out
  var REFERENCE_INDICES = [
    0,
    2,
    1,
    0,
    3,
    2, // right
    0,
    7,
    3,
    0,
    4,
    7, // start
    0,
    5,
    4,
    0,
    1,
    5, // bottom
    5,
    7,
    4,
    5,
    6,
    7, // left
    5,
    2,
    6,
    5,
    1,
    2, // end
    3,
    6,
    2,
    3,
    7,
    6, // top
  ];
  var REFERENCE_INDICES_LENGTH = REFERENCE_INDICES.length;

  // Decompose the "wall" into a series of shadow volumes.
  // Each shadow volume's vertices encode a description of the line it contains,
  // including mitering planes at the end points, a plane along the line itself,
  // and attributes for computing length-wise texture coordinates.
  function generateGeometryAttributes(
    loop,
    projection,
    bottomPositionsArray,
    topPositionsArray,
    normalsArray,
    cartographicsArray,
    compute2dAttributes
  ) {
    var i;
    var index;
    var ellipsoid = projection._ellipsoid;

    // Each segment will have 8 vertices
    var segmentCount = bottomPositionsArray.length / 3 - 1;
    var vertexCount = segmentCount * 8;
    var arraySizeVec4 = vertexCount * 4;
    var indexCount = segmentCount * 36;

    var indices =
      vertexCount > 65535
        ? new Uint32Array(indexCount)
        : new Uint16Array(indexCount);
    var positionsArray = new Float64Array(vertexCount * 3);

    var startHiAndForwardOffsetX = new Float32Array(arraySizeVec4);
    var startLoAndForwardOffsetY = new Float32Array(arraySizeVec4);
    var startNormalAndForwardOffsetZ = new Float32Array(arraySizeVec4);
    var endNormalAndTextureCoordinateNormalizationX = new Float32Array(
      arraySizeVec4
    );
    var rightNormalAndTextureCoordinateNormalizationY = new Float32Array(
      arraySizeVec4
    );

    var startHiLo2D;
    var offsetAndRight2D;
    var startEndNormals2D;
    var texcoordNormalization2D;

    if (compute2dAttributes) {
      startHiLo2D = new Float32Array(arraySizeVec4);
      offsetAndRight2D = new Float32Array(arraySizeVec4);
      startEndNormals2D = new Float32Array(arraySizeVec4);
      texcoordNormalization2D = new Float32Array(vertexCount * 2);
    }

    /*** Compute total lengths for texture coordinate normalization ***/
    // 2D
    var cartographicsLength = cartographicsArray.length / 2;
    var length2D = 0.0;

    var startCartographic = startCartographicScratch;
    startCartographic.height = 0.0;
    var endCartographic = endCartographicScratch;
    endCartographic.height = 0.0;

    var segmentStartCartesian = segmentStartTopScratch;
    var segmentEndCartesian = segmentEndTopScratch;

    if (compute2dAttributes) {
      index = 0;
      for (i = 1; i < cartographicsLength; i++) {
        // Don't clone anything from previous segment b/c possible IDL touch
        startCartographic.latitude = cartographicsArray[index];
        startCartographic.longitude = cartographicsArray[index + 1];
        endCartographic.latitude = cartographicsArray[index + 2];
        endCartographic.longitude = cartographicsArray[index + 3];

        segmentStartCartesian = projection.project(
          startCartographic,
          segmentStartCartesian
        );
        segmentEndCartesian = projection.project(
          endCartographic,
          segmentEndCartesian
        );
        length2D += Cartesian3.distance(
          segmentStartCartesian,
          segmentEndCartesian
        );
        index += 2;
      }
    }

    // 3D
    var positionsLength = topPositionsArray.length / 3;
    segmentEndCartesian = Cartesian3.unpack(
      topPositionsArray,
      0,
      segmentEndCartesian
    );
    var length3D = 0.0;

    index = 3;
    for (i = 1; i < positionsLength; i++) {
      segmentStartCartesian = Cartesian3.clone(
        segmentEndCartesian,
        segmentStartCartesian
      );
      segmentEndCartesian = Cartesian3.unpack(
        topPositionsArray,
        index,
        segmentEndCartesian
      );
      length3D += Cartesian3.distance(segmentStartCartesian, segmentEndCartesian);
      index += 3;
    }

    /*** Generate segments ***/
    var j;
    index = 3;
    var cartographicsIndex = 0;
    var vec2sWriteIndex = 0;
    var vec3sWriteIndex = 0;
    var vec4sWriteIndex = 0;
    var miterBroken = false;

    var endBottom = Cartesian3.unpack(
      bottomPositionsArray,
      0,
      segmentEndBottomScratch
    );
    var endTop = Cartesian3.unpack(topPositionsArray, 0, segmentEndTopScratch);
    var endGeometryNormal = Cartesian3.unpack(
      normalsArray,
      0,
      segmentEndNormalScratch
    );

    if (loop) {
      var preEndBottom = Cartesian3.unpack(
        bottomPositionsArray,
        bottomPositionsArray.length - 6,
        segmentStartBottomScratch
      );
      if (breakMiter(endGeometryNormal, preEndBottom, endBottom, endTop)) {
        // Miter broken as if for the last point in the loop, needs to be inverted for first point (clone of endBottom)
        endGeometryNormal = Cartesian3.negate(
          endGeometryNormal,
          endGeometryNormal
        );
      }
    }

    var lengthSoFar3D = 0.0;
    var lengthSoFar2D = 0.0;

    // For translating bounding volume
    var sumHeights = 0.0;

    for (i = 0; i < segmentCount; i++) {
      var startBottom = Cartesian3.clone(endBottom, segmentStartBottomScratch);
      var startTop = Cartesian3.clone(endTop, segmentStartTopScratch);
      var startGeometryNormal = Cartesian3.clone(
        endGeometryNormal,
        segmentStartNormalScratch
      );

      if (miterBroken) {
        startGeometryNormal = Cartesian3.negate(
          startGeometryNormal,
          startGeometryNormal
        );
      }

      endBottom = Cartesian3.unpack(
        bottomPositionsArray,
        index,
        segmentEndBottomScratch
      );
      endTop = Cartesian3.unpack(topPositionsArray, index, segmentEndTopScratch);
      endGeometryNormal = Cartesian3.unpack(
        normalsArray,
        index,
        segmentEndNormalScratch
      );

      miterBroken = breakMiter(endGeometryNormal, startBottom, endBottom, endTop);

      // 2D - don't clone anything from previous segment b/c possible IDL touch
      startCartographic.latitude = cartographicsArray[cartographicsIndex];
      startCartographic.longitude = cartographicsArray[cartographicsIndex + 1];
      endCartographic.latitude = cartographicsArray[cartographicsIndex + 2];
      endCartographic.longitude = cartographicsArray[cartographicsIndex + 3];
      var start2D;
      var end2D;
      var startGeometryNormal2D;
      var endGeometryNormal2D;

      if (compute2dAttributes) {
        var nudgeResult = nudgeCartographic(startCartographic, endCartographic);
        start2D = projection.project(startCartographic, segmentStart2DScratch);
        end2D = projection.project(endCartographic, segmentEnd2DScratch);
        var direction2D = direction(end2D, start2D, forwardOffset2DScratch);
        direction2D.y = Math.abs(direction2D.y);

        startGeometryNormal2D = segmentStartNormal2DScratch;
        endGeometryNormal2D = segmentEndNormal2DScratch;
        if (
          nudgeResult === 0 ||
          Cartesian3.dot(direction2D, Cartesian3.UNIT_Y) > MITER_BREAK_SMALL
        ) {
          // No nudge - project the original normal
          // Or, if the line's angle relative to the IDL is very acute,
          // in which case snapping will produce oddly shaped volumes.
          startGeometryNormal2D = projectNormal(
            projection,
            startCartographic,
            startGeometryNormal,
            start2D,
            segmentStartNormal2DScratch
          );
          endGeometryNormal2D = projectNormal(
            projection,
            endCartographic,
            endGeometryNormal,
            end2D,
            segmentEndNormal2DScratch
          );
        } else if (nudgeResult === 1) {
          // Start is close to IDL - snap start normal to align with IDL
          endGeometryNormal2D = projectNormal(
            projection,
            endCartographic,
            endGeometryNormal,
            end2D,
            segmentEndNormal2DScratch
          );
          startGeometryNormal2D.x = 0.0;
          // If start longitude is negative and end longitude is less negative, relative right is unit -Y
          // If start longitude is positive and end longitude is less positive, relative right is unit +Y
          startGeometryNormal2D.y = CesiumMath.sign(
            startCartographic.longitude - Math.abs(endCartographic.longitude)
          );
          startGeometryNormal2D.z = 0.0;
        } else {
          // End is close to IDL - snap end normal to align with IDL
          startGeometryNormal2D = projectNormal(
            projection,
            startCartographic,
            startGeometryNormal,
            start2D,
            segmentStartNormal2DScratch
          );
          endGeometryNormal2D.x = 0.0;
          // If end longitude is negative and start longitude is less negative, relative right is unit Y
          // If end longitude is positive and start longitude is less positive, relative right is unit -Y
          endGeometryNormal2D.y = CesiumMath.sign(
            startCartographic.longitude - endCartographic.longitude
          );
          endGeometryNormal2D.z = 0.0;
        }
      }

      /****************************************
       * Geometry descriptors of a "line on terrain,"
       * as opposed to the "shadow volume used to draw
       * the line on terrain":
       * - position of start + offset to end
       * - start, end, and right-facing planes
       * - encoded texture coordinate offsets
       ****************************************/

      /* 3D */
      var segmentLength3D = Cartesian3.distance(startTop, endTop);

      var encodedStart = EncodedCartesian3.fromCartesian(
        startBottom,
        encodeScratch
      );
      var forwardOffset = Cartesian3.subtract(
        endBottom,
        startBottom,
        offsetScratch$1
      );
      var forward = Cartesian3.normalize(forwardOffset, rightScratch$1);

      var startUp = Cartesian3.subtract(startTop, startBottom, startUpScratch);
      startUp = Cartesian3.normalize(startUp, startUp);
      var rightNormal = Cartesian3.cross(forward, startUp, rightScratch$1);
      rightNormal = Cartesian3.normalize(rightNormal, rightNormal);

      var startPlaneNormal = Cartesian3.cross(
        startUp,
        startGeometryNormal,
        startPlaneNormalScratch
      );
      startPlaneNormal = Cartesian3.normalize(startPlaneNormal, startPlaneNormal);

      var endUp = Cartesian3.subtract(endTop, endBottom, endUpScratch);
      endUp = Cartesian3.normalize(endUp, endUp);
      var endPlaneNormal = Cartesian3.cross(
        endGeometryNormal,
        endUp,
        endPlaneNormalScratch
      );
      endPlaneNormal = Cartesian3.normalize(endPlaneNormal, endPlaneNormal);

      var texcoordNormalization3DX = segmentLength3D / length3D;
      var texcoordNormalization3DY = lengthSoFar3D / length3D;

      /* 2D */
      var segmentLength2D = 0.0;
      var encodedStart2D;
      var forwardOffset2D;
      var right2D;
      var texcoordNormalization2DX = 0.0;
      var texcoordNormalization2DY = 0.0;
      if (compute2dAttributes) {
        segmentLength2D = Cartesian3.distance(start2D, end2D);

        encodedStart2D = EncodedCartesian3.fromCartesian(
          start2D,
          encodeScratch2D
        );
        forwardOffset2D = Cartesian3.subtract(
          end2D,
          start2D,
          forwardOffset2DScratch
        );

        // Right direction is just forward direction rotated by -90 degrees around Z
        // Similarly with plane normals
        right2D = Cartesian3.normalize(forwardOffset2D, right2DScratch);
        var swap = right2D.x;
        right2D.x = right2D.y;
        right2D.y = -swap;

        texcoordNormalization2DX = segmentLength2D / length2D;
        texcoordNormalization2DY = lengthSoFar2D / length2D;
      }
      /** Pack **/
      for (j = 0; j < 8; j++) {
        var vec4Index = vec4sWriteIndex + j * 4;
        var vec2Index = vec2sWriteIndex + j * 2;
        var wIndex = vec4Index + 3;

        // Encode sidedness of vertex relative to right plane in texture coordinate normalization X,
        // whether vertex is top or bottom of volume in sign/magnitude of normalization Y.
        var rightPlaneSide = j < 4 ? 1.0 : -1.0;
        var topBottomSide = j === 2 || j === 3 || j === 6 || j === 7 ? 1.0 : -1.0;

        // 3D
        Cartesian3.pack(encodedStart.high, startHiAndForwardOffsetX, vec4Index);
        startHiAndForwardOffsetX[wIndex] = forwardOffset.x;

        Cartesian3.pack(encodedStart.low, startLoAndForwardOffsetY, vec4Index);
        startLoAndForwardOffsetY[wIndex] = forwardOffset.y;

        Cartesian3.pack(
          startPlaneNormal,
          startNormalAndForwardOffsetZ,
          vec4Index
        );
        startNormalAndForwardOffsetZ[wIndex] = forwardOffset.z;

        Cartesian3.pack(
          endPlaneNormal,
          endNormalAndTextureCoordinateNormalizationX,
          vec4Index
        );
        endNormalAndTextureCoordinateNormalizationX[wIndex] =
          texcoordNormalization3DX * rightPlaneSide;

        Cartesian3.pack(
          rightNormal,
          rightNormalAndTextureCoordinateNormalizationY,
          vec4Index
        );

        var texcoordNormalization = texcoordNormalization3DY * topBottomSide;
        if (texcoordNormalization === 0.0 && topBottomSide < 0.0) {
          texcoordNormalization = 9.0; // some value greater than 1.0
        }
        rightNormalAndTextureCoordinateNormalizationY[
          wIndex
        ] = texcoordNormalization;

        // 2D
        if (compute2dAttributes) {
          startHiLo2D[vec4Index] = encodedStart2D.high.x;
          startHiLo2D[vec4Index + 1] = encodedStart2D.high.y;
          startHiLo2D[vec4Index + 2] = encodedStart2D.low.x;
          startHiLo2D[vec4Index + 3] = encodedStart2D.low.y;

          startEndNormals2D[vec4Index] = -startGeometryNormal2D.y;
          startEndNormals2D[vec4Index + 1] = startGeometryNormal2D.x;
          startEndNormals2D[vec4Index + 2] = endGeometryNormal2D.y;
          startEndNormals2D[vec4Index + 3] = -endGeometryNormal2D.x;

          offsetAndRight2D[vec4Index] = forwardOffset2D.x;
          offsetAndRight2D[vec4Index + 1] = forwardOffset2D.y;
          offsetAndRight2D[vec4Index + 2] = right2D.x;
          offsetAndRight2D[vec4Index + 3] = right2D.y;

          texcoordNormalization2D[vec2Index] =
            texcoordNormalization2DX * rightPlaneSide;

          texcoordNormalization = texcoordNormalization2DY * topBottomSide;
          if (texcoordNormalization === 0.0 && topBottomSide < 0.0) {
            texcoordNormalization = 9.0; // some value greater than 1.0
          }
          texcoordNormalization2D[vec2Index + 1] = texcoordNormalization;
        }
      }

      // Adjust height of volume in 3D
      var adjustHeightStartBottom = adjustHeightStartBottomScratch;
      var adjustHeightEndBottom = adjustHeightEndBottomScratch;
      var adjustHeightStartTop = adjustHeightStartTopScratch;
      var adjustHeightEndTop = adjustHeightEndTopScratch;

      var getHeightsRectangle = Rectangle.fromCartographicArray(
        getHeightCartographics,
        getHeightRectangleScratch
      );
      var minMaxHeights = ApproximateTerrainHeights.getMinimumMaximumHeights(
        getHeightsRectangle,
        ellipsoid
      );
      var minHeight = minMaxHeights.minimumTerrainHeight;
      var maxHeight = minMaxHeights.maximumTerrainHeight;

      sumHeights += minHeight;
      sumHeights += maxHeight;

      adjustHeights(
        startBottom,
        startTop,
        minHeight,
        maxHeight,
        adjustHeightStartBottom,
        adjustHeightStartTop
      );
      adjustHeights(
        endBottom,
        endTop,
        minHeight,
        maxHeight,
        adjustHeightEndBottom,
        adjustHeightEndTop
      );

      // Nudge the positions away from the "polyline" a little bit to prevent errors in GeometryPipeline
      var normalNudge = Cartesian3.multiplyByScalar(
        rightNormal,
        CesiumMath.EPSILON5,
        normalNudgeScratch
      );
      Cartesian3.add(
        adjustHeightStartBottom,
        normalNudge,
        adjustHeightStartBottom
      );
      Cartesian3.add(adjustHeightEndBottom, normalNudge, adjustHeightEndBottom);
      Cartesian3.add(adjustHeightStartTop, normalNudge, adjustHeightStartTop);
      Cartesian3.add(adjustHeightEndTop, normalNudge, adjustHeightEndTop);

      // If the segment is very close to the XZ plane, nudge the vertices slightly to avoid touching it.
      nudgeXZ(adjustHeightStartBottom, adjustHeightEndBottom);
      nudgeXZ(adjustHeightStartTop, adjustHeightEndTop);

      Cartesian3.pack(adjustHeightStartBottom, positionsArray, vec3sWriteIndex);
      Cartesian3.pack(adjustHeightEndBottom, positionsArray, vec3sWriteIndex + 3);
      Cartesian3.pack(adjustHeightEndTop, positionsArray, vec3sWriteIndex + 6);
      Cartesian3.pack(adjustHeightStartTop, positionsArray, vec3sWriteIndex + 9);

      normalNudge = Cartesian3.multiplyByScalar(
        rightNormal,
        -2.0 * CesiumMath.EPSILON5,
        normalNudgeScratch
      );
      Cartesian3.add(
        adjustHeightStartBottom,
        normalNudge,
        adjustHeightStartBottom
      );
      Cartesian3.add(adjustHeightEndBottom, normalNudge, adjustHeightEndBottom);
      Cartesian3.add(adjustHeightStartTop, normalNudge, adjustHeightStartTop);
      Cartesian3.add(adjustHeightEndTop, normalNudge, adjustHeightEndTop);

      nudgeXZ(adjustHeightStartBottom, adjustHeightEndBottom);
      nudgeXZ(adjustHeightStartTop, adjustHeightEndTop);

      Cartesian3.pack(
        adjustHeightStartBottom,
        positionsArray,
        vec3sWriteIndex + 12
      );
      Cartesian3.pack(
        adjustHeightEndBottom,
        positionsArray,
        vec3sWriteIndex + 15
      );
      Cartesian3.pack(adjustHeightEndTop, positionsArray, vec3sWriteIndex + 18);
      Cartesian3.pack(adjustHeightStartTop, positionsArray, vec3sWriteIndex + 21);

      cartographicsIndex += 2;
      index += 3;

      vec2sWriteIndex += 16;
      vec3sWriteIndex += 24;
      vec4sWriteIndex += 32;

      lengthSoFar3D += segmentLength3D;
      lengthSoFar2D += segmentLength2D;
    }

    index = 0;
    var indexOffset = 0;
    for (i = 0; i < segmentCount; i++) {
      for (j = 0; j < REFERENCE_INDICES_LENGTH; j++) {
        indices[index + j] = REFERENCE_INDICES[j] + indexOffset;
      }
      indexOffset += 8;
      index += REFERENCE_INDICES_LENGTH;
    }

    var boundingSpheres = scratchBoundingSpheres;
    BoundingSphere.fromVertices(
      bottomPositionsArray,
      Cartesian3.ZERO,
      3,
      boundingSpheres[0]
    );
    BoundingSphere.fromVertices(
      topPositionsArray,
      Cartesian3.ZERO,
      3,
      boundingSpheres[1]
    );
    var boundingSphere = BoundingSphere.fromBoundingSpheres(boundingSpheres);

    // Adjust bounding sphere height and radius to cover more of the volume
    boundingSphere.radius += sumHeights / (segmentCount * 2.0);

    var attributes = {
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        normalize: false,
        values: positionsArray,
      }),
      startHiAndForwardOffsetX: getVec4GeometryAttribute(
        startHiAndForwardOffsetX
      ),
      startLoAndForwardOffsetY: getVec4GeometryAttribute(
        startLoAndForwardOffsetY
      ),
      startNormalAndForwardOffsetZ: getVec4GeometryAttribute(
        startNormalAndForwardOffsetZ
      ),
      endNormalAndTextureCoordinateNormalizationX: getVec4GeometryAttribute(
        endNormalAndTextureCoordinateNormalizationX
      ),
      rightNormalAndTextureCoordinateNormalizationY: getVec4GeometryAttribute(
        rightNormalAndTextureCoordinateNormalizationY
      ),
    };

    if (compute2dAttributes) {
      attributes.startHiLo2D = getVec4GeometryAttribute(startHiLo2D);
      attributes.offsetAndRight2D = getVec4GeometryAttribute(offsetAndRight2D);
      attributes.startEndNormals2D = getVec4GeometryAttribute(startEndNormals2D);
      attributes.texcoordNormalization2D = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        normalize: false,
        values: texcoordNormalization2D,
      });
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      boundingSphere: boundingSphere,
    });
  }

  function getVec4GeometryAttribute(typedArray) {
    return new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 4,
      normalize: false,
      values: typedArray,
    });
  }

  /**
   * Approximates an ellipsoid-tangent vector in 2D by projecting the end point into 2D.
   * Exposed for testing.
   *
   * @param {MapProjection} projection Map Projection for projecting coordinates to 2D.
   * @param {Cartographic} cartographic The cartographic origin point of the normal.
   *   Used to check if the normal crosses the IDL during projection.
   * @param {Cartesian3} normal The normal in 3D.
   * @param {Cartesian3} projectedPosition The projected origin point of the normal in 2D.
   * @param {Cartesian3} result Result parameter on which to store the projected normal.
   * @private
   */
  GroundPolylineGeometry._projectNormal = projectNormal;

  /**
   * Defines a heading angle, pitch angle, and range in a local frame.
   * Heading is the rotation from the local north direction where a positive angle is increasing eastward.
   * Pitch is the rotation from the local xy-plane. Positive pitch angles are above the plane. Negative pitch
   * angles are below the plane. Range is the distance from the center of the frame.
   * @alias HeadingPitchRange
   * @constructor
   *
   * @param {Number} [heading=0.0] The heading angle in radians.
   * @param {Number} [pitch=0.0] The pitch angle in radians.
   * @param {Number} [range=0.0] The distance from the center in meters.
   */
  function HeadingPitchRange(heading, pitch, range) {
    /**
     * Heading is the rotation from the local north direction where a positive angle is increasing eastward.
     * @type {Number}
     * @default 0.0
     */
    this.heading = defaultValue(heading, 0.0);

    /**
     * Pitch is the rotation from the local xy-plane. Positive pitch angles
     * are above the plane. Negative pitch angles are below the plane.
     * @type {Number}
     * @default 0.0
     */
    this.pitch = defaultValue(pitch, 0.0);

    /**
     * Range is the distance from the center of the local frame.
     * @type {Number}
     * @default 0.0
     */
    this.range = defaultValue(range, 0.0);
  }

  /**
   * Duplicates a HeadingPitchRange instance.
   *
   * @param {HeadingPitchRange} hpr The HeadingPitchRange to duplicate.
   * @param {HeadingPitchRange} [result] The object onto which to store the result.
   * @returns {HeadingPitchRange} The modified result parameter or a new HeadingPitchRange instance if one was not provided. (Returns undefined if hpr is undefined)
   */
  HeadingPitchRange.clone = function (hpr, result) {
    if (!defined(hpr)) {
      return undefined;
    }
    if (!defined(result)) {
      result = new HeadingPitchRange();
    }

    result.heading = hpr.heading;
    result.pitch = hpr.pitch;
    result.range = hpr.range;
    return result;
  };

  var factorial = CesiumMath.factorial;

  function calculateCoefficientTerm(
    x,
    zIndices,
    xTable,
    derivOrder,
    termOrder,
    reservedIndices
  ) {
    var result = 0;
    var reserved;
    var i;
    var j;

    if (derivOrder > 0) {
      for (i = 0; i < termOrder; i++) {
        reserved = false;
        for (j = 0; j < reservedIndices.length && !reserved; j++) {
          if (i === reservedIndices[j]) {
            reserved = true;
          }
        }

        if (!reserved) {
          reservedIndices.push(i);
          result += calculateCoefficientTerm(
            x,
            zIndices,
            xTable,
            derivOrder - 1,
            termOrder,
            reservedIndices
          );
          reservedIndices.splice(reservedIndices.length - 1, 1);
        }
      }

      return result;
    }

    result = 1;
    for (i = 0; i < termOrder; i++) {
      reserved = false;
      for (j = 0; j < reservedIndices.length && !reserved; j++) {
        if (i === reservedIndices[j]) {
          reserved = true;
        }
      }

      if (!reserved) {
        result *= x - xTable[zIndices[i]];
      }
    }

    return result;
  }

  /**
   * An {@link InterpolationAlgorithm} for performing Hermite interpolation.
   *
   * @namespace HermitePolynomialApproximation
   */
  var HermitePolynomialApproximation = {
    type: "Hermite",
  };

  /**
   * Given the desired degree, returns the number of data points required for interpolation.
   *
   * @param {Number} degree The desired degree of interpolation.
   * @param {Number} [inputOrder=0]  The order of the inputs (0 means just the data, 1 means the data and its derivative, etc).
   * @returns {Number} The number of required data points needed for the desired degree of interpolation.
   * @exception {DeveloperError} degree must be 0 or greater.
   * @exception {DeveloperError} inputOrder must be 0 or greater.
   */
  HermitePolynomialApproximation.getRequiredDataPoints = function (
    degree,
    inputOrder
  ) {
    inputOrder = defaultValue(inputOrder, 0);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(degree)) {
      throw new DeveloperError("degree is required.");
    }
    if (degree < 0) {
      throw new DeveloperError("degree must be 0 or greater.");
    }
    if (inputOrder < 0) {
      throw new DeveloperError("inputOrder must be 0 or greater.");
    }
    //>>includeEnd('debug');

    return Math.max(Math.floor((degree + 1) / (inputOrder + 1)), 2);
  };

  /**
   * Interpolates values using Hermite Polynomial Approximation.
   *
   * @param {Number} x The independent variable for which the dependent variables will be interpolated.
   * @param {Number[]} xTable The array of independent variables to use to interpolate.  The values
   * in this array must be in increasing order and the same value must not occur twice in the array.
   * @param {Number[]} yTable The array of dependent variables to use to interpolate.  For a set of three
   * dependent values (p,q,w) at time 1 and time 2 this should be as follows: {p1, q1, w1, p2, q2, w2}.
   * @param {Number} yStride The number of dependent variable values in yTable corresponding to
   * each independent variable value in xTable.
   * @param {Number[]} [result] An existing array into which to store the result.
   * @returns {Number[]} The array of interpolated values, or the result parameter if one was provided.
   */
  HermitePolynomialApproximation.interpolateOrderZero = function (
    x,
    xTable,
    yTable,
    yStride,
    result
  ) {
    if (!defined(result)) {
      result = new Array(yStride);
    }

    var i;
    var j;
    var d;
    var s;
    var len;
    var index;
    var length = xTable.length;
    var coefficients = new Array(yStride);

    for (i = 0; i < yStride; i++) {
      result[i] = 0;

      var l = new Array(length);
      coefficients[i] = l;
      for (j = 0; j < length; j++) {
        l[j] = [];
      }
    }

    var zIndicesLength = length,
      zIndices = new Array(zIndicesLength);

    for (i = 0; i < zIndicesLength; i++) {
      zIndices[i] = i;
    }

    var highestNonZeroCoef = length - 1;
    for (s = 0; s < yStride; s++) {
      for (j = 0; j < zIndicesLength; j++) {
        index = zIndices[j] * yStride + s;
        coefficients[s][0].push(yTable[index]);
      }

      for (i = 1; i < zIndicesLength; i++) {
        var nonZeroCoefficients = false;
        for (j = 0; j < zIndicesLength - i; j++) {
          var zj = xTable[zIndices[j]];
          var zn = xTable[zIndices[j + i]];

          var numerator;
          if (zn - zj <= 0) {
            index = zIndices[j] * yStride + yStride * i + s;
            numerator = yTable[index];
            coefficients[s][i].push(numerator / factorial(i));
          } else {
            numerator = coefficients[s][i - 1][j + 1] - coefficients[s][i - 1][j];
            coefficients[s][i].push(numerator / (zn - zj));
          }
          nonZeroCoefficients = nonZeroCoefficients || numerator !== 0;
        }

        if (!nonZeroCoefficients) {
          highestNonZeroCoef = i - 1;
        }
      }
    }

    for (d = 0, len = 0; d <= len; d++) {
      for (i = d; i <= highestNonZeroCoef; i++) {
        var tempTerm = calculateCoefficientTerm(x, zIndices, xTable, d, i, []);
        for (s = 0; s < yStride; s++) {
          var coeff = coefficients[s][i][0];
          result[s + d * yStride] += coeff * tempTerm;
        }
      }
    }

    return result;
  };

  var arrayScratch$1 = [];

  /**
   * Interpolates values using Hermite Polynomial Approximation.
   *
   * @param {Number} x The independent variable for which the dependent variables will be interpolated.
   * @param {Number[]} xTable The array of independent variables to use to interpolate.  The values
   * in this array must be in increasing order and the same value must not occur twice in the array.
   * @param {Number[]} yTable The array of dependent variables to use to interpolate.  For a set of three
   * dependent values (p,q,w) at time 1 and time 2 this should be as follows: {p1, q1, w1, p2, q2, w2}.
   * @param {Number} yStride The number of dependent variable values in yTable corresponding to
   * each independent variable value in xTable.
   * @param {Number} inputOrder The number of derivatives supplied for input.
   * @param {Number} outputOrder The number of derivatives desired for output.
   * @param {Number[]} [result] An existing array into which to store the result.
   *
   * @returns {Number[]} The array of interpolated values, or the result parameter if one was provided.
   */
  HermitePolynomialApproximation.interpolate = function (
    x,
    xTable,
    yTable,
    yStride,
    inputOrder,
    outputOrder,
    result
  ) {
    var resultLength = yStride * (outputOrder + 1);
    if (!defined(result)) {
      result = new Array(resultLength);
    }
    for (var r = 0; r < resultLength; r++) {
      result[r] = 0;
    }

    var length = xTable.length;
    // The zIndices array holds copies of the addresses of the xTable values
    // in the range we're looking at. Even though this just holds information already
    // available in xTable this is a much more convenient format.
    var zIndices = new Array(length * (inputOrder + 1));
    var i;
    for (i = 0; i < length; i++) {
      for (var j = 0; j < inputOrder + 1; j++) {
        zIndices[i * (inputOrder + 1) + j] = i;
      }
    }

    var zIndiceslength = zIndices.length;
    var coefficients = arrayScratch$1;
    var highestNonZeroCoef = fillCoefficientList(
      coefficients,
      zIndices,
      xTable,
      yTable,
      yStride,
      inputOrder
    );
    var reservedIndices = [];

    var tmp = (zIndiceslength * (zIndiceslength + 1)) / 2;
    var loopStop = Math.min(highestNonZeroCoef, outputOrder);
    for (var d = 0; d <= loopStop; d++) {
      for (i = d; i <= highestNonZeroCoef; i++) {
        reservedIndices.length = 0;
        var tempTerm = calculateCoefficientTerm(
          x,
          zIndices,
          xTable,
          d,
          i,
          reservedIndices
        );
        var dimTwo = Math.floor((i * (1 - i)) / 2) + zIndiceslength * i;

        for (var s = 0; s < yStride; s++) {
          var dimOne = Math.floor(s * tmp);
          var coef = coefficients[dimOne + dimTwo];
          result[s + d * yStride] += coef * tempTerm;
        }
      }
    }

    return result;
  };

  function fillCoefficientList(
    coefficients,
    zIndices,
    xTable,
    yTable,
    yStride,
    inputOrder
  ) {
    var j;
    var index;
    var highestNonZero = -1;
    var zIndiceslength = zIndices.length;
    var tmp = (zIndiceslength * (zIndiceslength + 1)) / 2;

    for (var s = 0; s < yStride; s++) {
      var dimOne = Math.floor(s * tmp);

      for (j = 0; j < zIndiceslength; j++) {
        index = zIndices[j] * yStride * (inputOrder + 1) + s;
        coefficients[dimOne + j] = yTable[index];
      }

      for (var i = 1; i < zIndiceslength; i++) {
        var coefIndex = 0;
        var dimTwo = Math.floor((i * (1 - i)) / 2) + zIndiceslength * i;
        var nonZeroCoefficients = false;

        for (j = 0; j < zIndiceslength - i; j++) {
          var zj = xTable[zIndices[j]];
          var zn = xTable[zIndices[j + i]];

          var numerator;
          var coefficient;
          if (zn - zj <= 0) {
            index = zIndices[j] * yStride * (inputOrder + 1) + yStride * i + s;
            numerator = yTable[index];
            coefficient = numerator / CesiumMath.factorial(i);
            coefficients[dimOne + dimTwo + coefIndex] = coefficient;
            coefIndex++;
          } else {
            var dimTwoMinusOne =
              Math.floor(((i - 1) * (2 - i)) / 2) + zIndiceslength * (i - 1);
            numerator =
              coefficients[dimOne + dimTwoMinusOne + j + 1] -
              coefficients[dimOne + dimTwoMinusOne + j];
            coefficient = numerator / (zn - zj);
            coefficients[dimOne + dimTwo + coefIndex] = coefficient;
            coefIndex++;
          }
          nonZeroCoefficients = nonZeroCoefficients || numerator !== 0.0;
        }

        if (nonZeroCoefficients) {
          highestNonZero = Math.max(highestNonZero, i);
        }
      }
    }

    return highestNonZero;
  }

  /**
   * A structure containing the orientation data computed at a particular time. The data
   * represents the direction of the pole of rotation and the rotation about that pole.
   * <p>
   * These parameters correspond to the parameters in the Report from the IAU/IAG Working Group
   * except that they are expressed in radians.
   * </p>
   *
   * @namespace IauOrientationParameters
   *
   * @private
   */
  function IauOrientationParameters(
    rightAscension,
    declination,
    rotation,
    rotationRate
  ) {
    /**
     * The right ascension of the north pole of the body with respect to
     * the International Celestial Reference Frame, in radians.
     * @type {Number}
     *
     * @private
     */
    this.rightAscension = rightAscension;

    /**
     * The declination of the north pole of the body with respect to
     * the International Celestial Reference Frame, in radians.
     * @type {Number}
     *
     * @private
     */
    this.declination = declination;

    /**
     * The rotation about the north pole used to align a set of axes with
     * the meridian defined by the IAU report, in radians.
     * @type {Number}
     *
     * @private
     */
    this.rotation = rotation;

    /**
     * The instantaneous rotation rate about the north pole, in radians per second.
     * @type {Number}
     *
     * @private
     */
    this.rotationRate = rotationRate;
  }

  /**
   * This is a collection of the orientation information available for central bodies.
   * The data comes from the Report of the IAU/IAG Working Group on Cartographic
   * Coordinates and Rotational Elements: 2000.
   *
   * @namespace Iau2000Orientation
   *
   * @private
   */
  var Iau2000Orientation = {};

  var TdtMinusTai = 32.184;
  var J2000d = 2451545.0;

  var c1 = -0.0529921;
  var c2 = -0.1059842;
  var c3$1 = 13.0120009;
  var c4 = 13.3407154;
  var c5 = 0.9856003;
  var c6 = 26.4057084;
  var c7 = 13.064993;
  var c8 = 0.3287146;
  var c9 = 1.7484877;
  var c10 = -0.1589763;
  var c11 = 0.0036096;
  var c12 = 0.1643573;
  var c13 = 12.9590088;
  var dateTT = new JulianDate();

  /**
   * Compute the orientation parameters for the Moon.
   *
   * @param {JulianDate} [date=JulianDate.now()] The date to evaluate the parameters.
   * @param {IauOrientationParameters} [result] The object onto which to store the result.
   * @returns {IauOrientationParameters} The modified result parameter or a new instance representing the orientation of the Earth's Moon.
   * @private
   */
  Iau2000Orientation.ComputeMoon = function (date, result) {
    if (!defined(date)) {
      date = JulianDate.now();
    }

    dateTT = JulianDate.addSeconds(date, TdtMinusTai, dateTT);
    var d = JulianDate.totalDays(dateTT) - J2000d;
    var T = d / TimeConstants$1.DAYS_PER_JULIAN_CENTURY;

    var E1 = (125.045 + c1 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E2 = (250.089 + c2 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E3 = (260.008 + c3$1 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E4 = (176.625 + c4 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E5 = (357.529 + c5 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E6 = (311.589 + c6 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E7 = (134.963 + c7 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E8 = (276.617 + c8 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E9 = (34.226 + c9 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E10 = (15.134 + c10 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E11 = (119.743 + c11 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E12 = (239.961 + c12 * d) * CesiumMath.RADIANS_PER_DEGREE;
    var E13 = (25.053 + c13 * d) * CesiumMath.RADIANS_PER_DEGREE;

    var sinE1 = Math.sin(E1);
    var sinE2 = Math.sin(E2);
    var sinE3 = Math.sin(E3);
    var sinE4 = Math.sin(E4);
    var sinE5 = Math.sin(E5);
    var sinE6 = Math.sin(E6);
    var sinE7 = Math.sin(E7);
    var sinE8 = Math.sin(E8);
    var sinE9 = Math.sin(E9);
    var sinE10 = Math.sin(E10);
    var sinE11 = Math.sin(E11);
    var sinE12 = Math.sin(E12);
    var sinE13 = Math.sin(E13);

    var cosE1 = Math.cos(E1);
    var cosE2 = Math.cos(E2);
    var cosE3 = Math.cos(E3);
    var cosE4 = Math.cos(E4);
    var cosE5 = Math.cos(E5);
    var cosE6 = Math.cos(E6);
    var cosE7 = Math.cos(E7);
    var cosE8 = Math.cos(E8);
    var cosE9 = Math.cos(E9);
    var cosE10 = Math.cos(E10);
    var cosE11 = Math.cos(E11);
    var cosE12 = Math.cos(E12);
    var cosE13 = Math.cos(E13);

    var rightAscension =
      (269.9949 +
        0.0031 * T -
        3.8787 * sinE1 -
        0.1204 * sinE2 +
        0.07 * sinE3 -
        0.0172 * sinE4 +
        0.0072 * sinE6 -
        0.0052 * sinE10 +
        0.0043 * sinE13) *
      CesiumMath.RADIANS_PER_DEGREE;
    var declination =
      (66.5392 +
        0.013 * T +
        1.5419 * cosE1 +
        0.0239 * cosE2 -
        0.0278 * cosE3 +
        0.0068 * cosE4 -
        0.0029 * cosE6 +
        0.0009 * cosE7 +
        0.0008 * cosE10 -
        0.0009 * cosE13) *
      CesiumMath.RADIANS_PER_DEGREE;
    var rotation =
      (38.3213 +
        13.17635815 * d -
        1.4e-12 * d * d +
        3.561 * sinE1 +
        0.1208 * sinE2 -
        0.0642 * sinE3 +
        0.0158 * sinE4 +
        0.0252 * sinE5 -
        0.0066 * sinE6 -
        0.0047 * sinE7 -
        0.0046 * sinE8 +
        0.0028 * sinE9 +
        0.0052 * sinE10 +
        0.004 * sinE11 +
        0.0019 * sinE12 -
        0.0044 * sinE13) *
      CesiumMath.RADIANS_PER_DEGREE;

    var rotationRate =
      ((13.17635815 -
        1.4e-12 * (2.0 * d) +
        3.561 * cosE1 * c1 +
        0.1208 * cosE2 * c2 -
        0.0642 * cosE3 * c3$1 +
        0.0158 * cosE4 * c4 +
        0.0252 * cosE5 * c5 -
        0.0066 * cosE6 * c6 -
        0.0047 * cosE7 * c7 -
        0.0046 * cosE8 * c8 +
        0.0028 * cosE9 * c9 +
        0.0052 * cosE10 * c10 +
        0.004 * cosE11 * c11 +
        0.0019 * cosE12 * c12 -
        0.0044 * cosE13 * c13) /
        86400.0) *
      CesiumMath.RADIANS_PER_DEGREE;

    if (!defined(result)) {
      result = new IauOrientationParameters();
    }

    result.rightAscension = rightAscension;
    result.declination = declination;
    result.rotation = rotation;
    result.rotationRate = rotationRate;

    return result;
  };

  /**
   * The Axes representing the orientation of a Globe as represented by the data
   * from the IAU/IAG Working Group reports on rotational elements.
   * @alias IauOrientationAxes
   * @constructor
   *
   * @param {IauOrientationAxes.ComputeFunction} [computeFunction] The function that computes the {@link IauOrientationParameters} given a {@link JulianDate}.
   *
   * @see Iau2000Orientation
   *
   * @private
   */
  function IauOrientationAxes(computeFunction) {
    if (!defined(computeFunction) || typeof computeFunction !== "function") {
      computeFunction = Iau2000Orientation.ComputeMoon;
    }

    this._computeFunction = computeFunction;
  }

  var xAxisScratch = new Cartesian3();
  var yAxisScratch = new Cartesian3();
  var zAxisScratch = new Cartesian3();

  function computeRotationMatrix(alpha, delta, result) {
    var xAxis = xAxisScratch;
    xAxis.x = Math.cos(alpha + CesiumMath.PI_OVER_TWO);
    xAxis.y = Math.sin(alpha + CesiumMath.PI_OVER_TWO);
    xAxis.z = 0.0;

    var cosDec = Math.cos(delta);

    var zAxis = zAxisScratch;
    zAxis.x = cosDec * Math.cos(alpha);
    zAxis.y = cosDec * Math.sin(alpha);
    zAxis.z = Math.sin(delta);

    var yAxis = Cartesian3.cross(zAxis, xAxis, yAxisScratch);

    if (!defined(result)) {
      result = new Matrix3();
    }

    result[0] = xAxis.x;
    result[1] = yAxis.x;
    result[2] = zAxis.x;
    result[3] = xAxis.y;
    result[4] = yAxis.y;
    result[5] = zAxis.y;
    result[6] = xAxis.z;
    result[7] = yAxis.z;
    result[8] = zAxis.z;

    return result;
  }

  var rotMtxScratch = new Matrix3();
  var quatScratch = new Quaternion();

  /**
   * Computes a rotation from ICRF to a Globe's Fixed axes.
   *
   * @param {JulianDate} date The date to evaluate the matrix.
   * @param {Matrix3} result The object onto which to store the result.
   * @returns {Matrix3} The modified result parameter or a new instance of the rotation from ICRF to Fixed.
   */
  IauOrientationAxes.prototype.evaluate = function (date, result) {
    if (!defined(date)) {
      date = JulianDate.now();
    }

    var alphaDeltaW = this._computeFunction(date);
    var precMtx = computeRotationMatrix(
      alphaDeltaW.rightAscension,
      alphaDeltaW.declination,
      result
    );

    var rot = CesiumMath.zeroToTwoPi(alphaDeltaW.rotation);
    var quat = Quaternion.fromAxisAngle(Cartesian3.UNIT_Z, rot, quatScratch);
    var rotMtx = Matrix3.fromQuaternion(
      Quaternion.conjugate(quat, quat),
      rotMtxScratch
    );

    var cbi2cbf = Matrix3.multiply(rotMtx, precMtx, precMtx);
    return cbi2cbf;
  };

  /**
   * The interface for interpolation algorithms.
   *
   * @interface InterpolationAlgorithm
   *
   * @see LagrangePolynomialApproximation
   * @see LinearApproximation
   * @see HermitePolynomialApproximation
   */
  var InterpolationAlgorithm = {};

  /**
   * Gets the name of this interpolation algorithm.
   * @type {String}
   */
  InterpolationAlgorithm.type = undefined;

  /**
   * Given the desired degree, returns the number of data points required for interpolation.
   * @function
   *
   * @param {Number} degree The desired degree of interpolation.
   * @returns {Number} The number of required data points needed for the desired degree of interpolation.
   */
  InterpolationAlgorithm.getRequiredDataPoints =
    DeveloperError.throwInstantiationError;

  /**
   * Performs zero order interpolation.
   * @function
   *
   * @param {Number} x The independent variable for which the dependent variables will be interpolated.
   * @param {Number[]} xTable The array of independent variables to use to interpolate.  The values
   * in this array must be in increasing order and the same value must not occur twice in the array.
   * @param {Number[]} yTable The array of dependent variables to use to interpolate.  For a set of three
   * dependent values (p,q,w) at time 1 and time 2 this should be as follows: {p1, q1, w1, p2, q2, w2}.
   * @param {Number} yStride The number of dependent variable values in yTable corresponding to
   * each independent variable value in xTable.
   * @param {Number[]} [result] An existing array into which to store the result.
   *
   * @returns {Number[]} The array of interpolated values, or the result parameter if one was provided.
   */
  InterpolationAlgorithm.interpolateOrderZero =
    DeveloperError.throwInstantiationError;

  /**
   * Performs higher order interpolation.  Not all interpolators need to support high-order interpolation,
   * if this function remains undefined on implementing objects, interpolateOrderZero will be used instead.
   * @function
   * @param {Number} x The independent variable for which the dependent variables will be interpolated.
   * @param {Number[]} xTable The array of independent variables to use to interpolate.  The values
   * in this array must be in increasing order and the same value must not occur twice in the array.
   * @param {Number[]} yTable The array of dependent variables to use to interpolate.  For a set of three
   * dependent values (p,q,w) at time 1 and time 2 this should be as follows: {p1, q1, w1, p2, q2, w2}.
   * @param {Number} yStride The number of dependent variable values in yTable corresponding to
   * each independent variable value in xTable.
   * @param {Number} inputOrder The number of derivatives supplied for input.
   * @param {Number} outputOrder The number of derivatives desired for output.
   * @param {Number[]} [result] An existing array into which to store the result.
   * @returns {Number[]} The array of interpolated values, or the result parameter if one was provided.
   */
  InterpolationAlgorithm.interpolate = DeveloperError.throwInstantiationError;

  var defaultTokenCredit;
  var defaultAccessToken =
    "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiI3N2JjMzBlOC1hZTdjLTQwZDItOTkxYi05M2JhMTI5ZGM0YWYiLCJpZCI6MjU5LCJzY29wZXMiOlsiYXNyIiwiZ2MiXSwiaWF0IjoxNTk2NDY1OTgyfQ.5YL6fQO9PaD4pomg0ivU1sD1FbFt1aCqzNXUcfk1eZw";
  /**
   * Default settings for accessing the Cesium ion API.
   *
   * An ion access token is only required if you are using any ion related APIs.
   * A default access token is provided for evaluation purposes only.
   * Sign up for a free ion account and get your own access token at {@link https://cesium.com}
   *
   * @see IonResource
   * @see IonImageryProvider
   * @see IonGeocoderService
   * @see createWorldImagery
   * @see createWorldTerrain
   * @namespace Ion
   */
  var Ion = {};

  /**
   * Gets or sets the default Cesium ion access token.
   *
   * @type {String}
   */
  Ion.defaultAccessToken = defaultAccessToken;

  /**
   * Gets or sets the default Cesium ion server.
   *
   * @type {String|Resource}
   * @default https://api.cesium.com
   */
  Ion.defaultServer = new Resource({ url: "https://api.cesium.com/" });

  Ion.getDefaultTokenCredit = function (providedKey) {
    if (providedKey !== defaultAccessToken) {
      return undefined;
    }

    if (!defined(defaultTokenCredit)) {
      var defaultTokenMessage =
        '<b> \
            This application is using Cesium\'s default ion access token. Please assign <i>Cesium.Ion.defaultAccessToken</i> \
            with an access token from your ion account before making any Cesium API calls. \
            You can sign up for a free ion account at <a href="https://cesium.com">https://cesium.com</a>.</b>';

      defaultTokenCredit = new Credit(defaultTokenMessage, true);
    }

    return defaultTokenCredit;
  };

  /**
   * Provides geocoding via a {@link https://pelias.io/|Pelias} server.
   * @alias PeliasGeocoderService
   * @constructor
   *
   * @param {Resource|String} url The endpoint to the Pelias server.
   *
   * @example
   * // Configure a Viewer to use the Pelias server hosted by https://geocode.earth/
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *   geocoder: new Cesium.PeliasGeocoderService(new Cesium.Resource({
   *     url: 'https://api.geocode.earth/v1/',
   *       queryParameters: {
   *         api_key: '<Your geocode.earth API key>'
   *     }
   *   }))
   * });
   */
  function PeliasGeocoderService(url) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("url", url);
    //>>includeEnd('debug');

    this._url = Resource.createIfNeeded(url);
    this._url.appendForwardSlash();
  }

  Object.defineProperties(PeliasGeocoderService.prototype, {
    /**
     * The Resource used to access the Pelias endpoint.
     * @type {Resource}
     * @memberof PeliasGeocoderService.prototype
     * @readonly
     */
    url: {
      get: function () {
        return this._url;
      },
    },
  });

  /**
   * @function
   *
   * @param {String} query The query to be sent to the geocoder service
   * @param {GeocodeType} [type=GeocodeType.SEARCH] The type of geocode to perform.
   * @returns {Promise<GeocoderService.Result[]>}
   */
  PeliasGeocoderService.prototype.geocode = function (query, type) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("query", query);
    //>>includeEnd('debug');

    var resource = this._url.getDerivedResource({
      url: type === GeocodeType$1.AUTOCOMPLETE ? "autocomplete" : "search",
      queryParameters: {
        text: query,
      },
    });

    return resource.fetchJson().then(function (results) {
      return results.features.map(function (resultObject) {
        var destination;
        var bboxDegrees = resultObject.bbox;

        if (defined(bboxDegrees)) {
          destination = Rectangle.fromDegrees(
            bboxDegrees[0],
            bboxDegrees[1],
            bboxDegrees[2],
            bboxDegrees[3]
          );
        } else {
          var lon = resultObject.geometry.coordinates[0];
          var lat = resultObject.geometry.coordinates[1];
          destination = Cartesian3.fromDegrees(lon, lat);
        }

        return {
          displayName: resultObject.properties.label,
          destination: destination,
        };
      });
    });
  };

  /**
   * Provides geocoding through Cesium ion.
   * @alias IonGeocoderService
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Scene} options.scene The scene
   * @param {String} [options.accessToken=Ion.defaultAccessToken] The access token to use.
   * @param {String|Resource} [options.server=Ion.defaultServer] The resource to the Cesium ion API server.
   *
   * @see Ion
   */
  function IonGeocoderService(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options.scene", options.scene);
    //>>includeEnd('debug');

    var accessToken = defaultValue(options.accessToken, Ion.defaultAccessToken);
    var server = Resource.createIfNeeded(
      defaultValue(options.server, Ion.defaultServer)
    );
    server.appendForwardSlash();

    var defaultTokenCredit = Ion.getDefaultTokenCredit(accessToken);
    if (defined(defaultTokenCredit)) {
      options.scene.frameState.creditDisplay.addDefaultCredit(
        Credit.clone(defaultTokenCredit)
      );
    }

    var searchEndpoint = server.getDerivedResource({
      url: "v1/geocode",
    });

    if (defined(accessToken)) {
      searchEndpoint.appendQueryParameters({ access_token: accessToken });
    }

    this._accessToken = accessToken;
    this._server = server;
    this._pelias = new PeliasGeocoderService(searchEndpoint);
  }

  /**
   * @function
   *
   * @param {String} query The query to be sent to the geocoder service
   * @param {GeocodeType} [type=GeocodeType.SEARCH] The type of geocode to perform.
   * @returns {Promise<GeocoderService.Result[]>}
   */
  IonGeocoderService.prototype.geocode = function (query, geocodeType) {
    return this._pelias.geocode(query, geocodeType);
  };

  /**
   * A {@link Resource} instance that encapsulates Cesium ion asset access.
   * This object is normally not instantiated directly, use {@link IonResource.fromAssetId}.
   *
   * @alias IonResource
   * @constructor
   * @augments Resource
   *
   * @param {Object} endpoint The result of the Cesium ion asset endpoint service.
   * @param {Resource} endpointResource The resource used to retreive the endpoint.
   *
   * @see Ion
   * @see IonImageryProvider
   * @see createWorldTerrain
   * @see https://cesium.com
   */
  function IonResource(endpoint, endpointResource) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("endpoint", endpoint);
    Check.defined("endpointResource", endpointResource);
    //>>includeEnd('debug');

    var options;
    var externalType = endpoint.externalType;
    var isExternal = defined(externalType);

    if (!isExternal) {
      options = {
        url: endpoint.url,
        retryAttempts: 1,
        retryCallback: retryCallback,
      };
    } else if (
      externalType === "3DTILES" ||
      externalType === "STK_TERRAIN_SERVER"
    ) {
      // 3D Tiles and STK Terrain Server external assets can still be represented as an IonResource
      options = { url: endpoint.options.url };
    } else {
      //External imagery assets have additional configuration that can't be represented as a Resource
      throw new RuntimeError(
        "Ion.createResource does not support external imagery assets; use IonImageryProvider instead."
      );
    }

    Resource.call(this, options);

    // The asset endpoint data returned from ion.
    this._ionEndpoint = endpoint;
    this._ionEndpointDomain = isExternal
      ? undefined
      : new URI(endpoint.url).authority;

    // The endpoint resource to fetch when a new token is needed
    this._ionEndpointResource = endpointResource;

    // The primary IonResource from which an instance is derived
    this._ionRoot = undefined;

    // Shared promise for endpooint requests amd credits (only ever set on the root request)
    this._pendingPromise = undefined;
    this._credits = undefined;
    this._isExternal = isExternal;
  }

  if (defined(Object.create)) {
    IonResource.prototype = Object.create(Resource.prototype);
    IonResource.prototype.constructor = IonResource;
  }

  /**
   * Asynchronously creates an instance.
   *
   * @param {Number} assetId The Cesium ion asset id.
   * @param {Object} [options] An object with the following properties:
   * @param {String} [options.accessToken=Ion.defaultAccessToken] The access token to use.
   * @param {String|Resource} [options.server=Ion.defaultServer] The resource to the Cesium ion API server.
   * @returns {Promise.<IonResource>} A Promise to am instance representing the Cesium ion Asset.
   *
   * @example
   * //Load a Cesium3DTileset with asset ID of 124624234
   * viewer.scene.primitives.add(new Cesium.Cesium3DTileset({ url: Cesium.IonResource.fromAssetId(124624234) }));
   *
   * @example
   * //Load a CZML file with asset ID of 10890
   * Cesium.IonResource.fromAssetId(10890)
   *   .then(function (resource) {
   *     viewer.dataSources.add(Cesium.CzmlDataSource.load(resource));
   *   });
   */
  IonResource.fromAssetId = function (assetId, options) {
    var endpointResource = IonResource._createEndpointResource(assetId, options);

    return endpointResource.fetchJson().then(function (endpoint) {
      return new IonResource(endpoint, endpointResource);
    });
  };

  Object.defineProperties(IonResource.prototype, {
    /**
     * Gets the credits required for attribution of the asset.
     *
     * @memberof IonResource.prototype
     * @type {Credit[]}
     * @readonly
     */
    credits: {
      get: function () {
        // Only we're not the root, return its credits;
        if (defined(this._ionRoot)) {
          return this._ionRoot.credits;
        }

        // We are the root
        if (defined(this._credits)) {
          return this._credits;
        }

        this._credits = IonResource.getCreditsFromEndpoint(
          this._ionEndpoint,
          this._ionEndpointResource
        );

        return this._credits;
      },
    },
  });

  /** @private */
  IonResource.getCreditsFromEndpoint = function (endpoint, endpointResource) {
    var credits = endpoint.attributions.map(Credit.getIonCredit);
    var defaultTokenCredit = Ion.getDefaultTokenCredit(
      endpointResource.queryParameters.access_token
    );
    if (defined(defaultTokenCredit)) {
      credits.push(Credit.clone(defaultTokenCredit));
    }
    return credits;
  };

  /** @inheritdoc */
  IonResource.prototype.clone = function (result) {
    // We always want to use the root's information because it's the most up-to-date
    var ionRoot = defaultValue(this._ionRoot, this);

    if (!defined(result)) {
      result = new IonResource(
        ionRoot._ionEndpoint,
        ionRoot._ionEndpointResource
      );
    }

    result = Resource.prototype.clone.call(this, result);
    result._ionRoot = ionRoot;
    result._isExternal = this._isExternal;

    return result;
  };

  IonResource.prototype.fetchImage = function (options) {
    if (!this._isExternal) {
      var userOptions = options;
      options = {
        preferBlob: true,
      };
      if (defined(userOptions)) {
        options.flipY = userOptions.flipY;
        options.preferImageBitmap = userOptions.preferImageBitmap;
      }
    }

    return Resource.prototype.fetchImage.call(this, options);
  };

  IonResource.prototype._makeRequest = function (options) {
    // Don't send ion access token to non-ion servers.
    if (
      this._isExternal ||
      new URI(this.url).authority !== this._ionEndpointDomain
    ) {
      return Resource.prototype._makeRequest.call(this, options);
    }

    if (!defined(options.headers)) {
      options.headers = {};
    }
    options.headers.Authorization = "Bearer " + this._ionEndpoint.accessToken;

    return Resource.prototype._makeRequest.call(this, options);
  };

  /**
   * @private
   */
  IonResource._createEndpointResource = function (assetId, options) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("assetId", assetId);
    //>>includeEnd('debug');

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var server = defaultValue(options.server, Ion.defaultServer);
    var accessToken = defaultValue(options.accessToken, Ion.defaultAccessToken);
    server = Resource.createIfNeeded(server);

    var resourceOptions = {
      url: "v1/assets/" + assetId + "/endpoint",
    };

    if (defined(accessToken)) {
      resourceOptions.queryParameters = { access_token: accessToken };
    }

    return server.getDerivedResource(resourceOptions);
  };

  function retryCallback(that, error) {
    var ionRoot = defaultValue(that._ionRoot, that);
    var endpointResource = ionRoot._ionEndpointResource;

    // We only want to retry in the case of invalid credentials (401) or image
    // requests(since Image failures can not provide a status code)
    if (
      !defined(error) ||
      (error.statusCode !== 401 && !(error.target instanceof Image))
    ) {
      return when.resolve(false);
    }

    // We use a shared pending promise for all derived assets, since they share
    // a common access_token.  If we're already requesting a new token for this
    // asset, we wait on the same promise.
    if (!defined(ionRoot._pendingPromise)) {
      ionRoot._pendingPromise = endpointResource
        .fetchJson()
        .then(function (newEndpoint) {
          //Set the token for root resource so new derived resources automatically pick it up
          ionRoot._ionEndpoint = newEndpoint;
          return newEndpoint;
        })
        .always(function (newEndpoint) {
          // Pass or fail, we're done with this promise, the next failure should use a new one.
          ionRoot._pendingPromise = undefined;
          return newEndpoint;
        });
    }

    return ionRoot._pendingPromise.then(function (newEndpoint) {
      // Set the new token and endpoint for this resource
      that._ionEndpoint = newEndpoint;
      return true;
    });
  }

  /**
   * An interval defined by a start and a stop time; optionally including those times as part of the interval.
   * Arbitrary data can optionally be associated with each instance for used with {@link TimeIntervalCollection}.
   *
   * @alias TimeInterval
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {JulianDate} [options.start=new JulianDate()] The start time of the interval.
   * @param {JulianDate} [options.stop=new JulianDate()] The stop time of the interval.
   * @param {Boolean} [options.isStartIncluded=true] <code>true</code> if <code>options.start</code> is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded=true] <code>true</code> if <code>options.stop</code> is included in the interval, <code>false</code> otherwise.
   * @param {Object} [options.data] Arbitrary data associated with this interval.
   *
   * @example
   * // Create an instance that spans August 1st, 1980 and is associated
   * // with a Cartesian position.
   * var timeInterval = new Cesium.TimeInterval({
   *     start : Cesium.JulianDate.fromIso8601('1980-08-01T00:00:00Z'),
   *     stop : Cesium.JulianDate.fromIso8601('1980-08-02T00:00:00Z'),
   *     isStartIncluded : true,
   *     isStopIncluded : false,
   *     data : Cesium.Cartesian3.fromDegrees(39.921037, -75.170082)
   * });
   *
   * @example
   * // Create two instances from ISO 8601 intervals with associated numeric data
   * // then compute their intersection, summing the data they contain.
   * var left = Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2000/2010',
   *     data : 2
   * });
   *
   * var right = Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '1995/2005',
   *     data : 3
   * });
   *
   * //The result of the below intersection will be an interval equivalent to
   * //var intersection = Cesium.TimeInterval.fromIso8601({
   * //  iso8601 : '2000/2005',
   * //  data : 5
   * //});
   * var intersection = new Cesium.TimeInterval();
   * Cesium.TimeInterval.intersect(left, right, intersection, function(leftData, rightData) {
   *     return leftData + rightData;
   * });
   *
   * @example
   * // Check if an interval contains a specific time.
   * var dateToCheck = Cesium.JulianDate.fromIso8601('1982-09-08T11:30:00Z');
   * var containsDate = Cesium.TimeInterval.contains(timeInterval, dateToCheck);
   */
  function TimeInterval(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    /**
     * Gets or sets the start time of this interval.
     * @type {JulianDate}
     */
    this.start = defined(options.start)
      ? JulianDate.clone(options.start)
      : new JulianDate();

    /**
     * Gets or sets the stop time of this interval.
     * @type {JulianDate}
     */
    this.stop = defined(options.stop)
      ? JulianDate.clone(options.stop)
      : new JulianDate();

    /**
     * Gets or sets the data associated with this interval.
     * @type {*}
     */
    this.data = options.data;

    /**
     * Gets or sets whether or not the start time is included in this interval.
     * @type {Boolean}
     * @default true
     */
    this.isStartIncluded = defaultValue(options.isStartIncluded, true);

    /**
     * Gets or sets whether or not the stop time is included in this interval.
     * @type {Boolean}
     * @default true
     */
    this.isStopIncluded = defaultValue(options.isStopIncluded, true);
  }

  Object.defineProperties(TimeInterval.prototype, {
    /**
     * Gets whether or not this interval is empty.
     * @memberof TimeInterval.prototype
     * @type {Boolean}
     * @readonly
     */
    isEmpty: {
      get: function () {
        var stopComparedToStart = JulianDate.compare(this.stop, this.start);
        return (
          stopComparedToStart < 0 ||
          (stopComparedToStart === 0 &&
            (!this.isStartIncluded || !this.isStopIncluded))
        );
      },
    },
  });

  var scratchInterval = {
    start: undefined,
    stop: undefined,
    isStartIncluded: undefined,
    isStopIncluded: undefined,
    data: undefined,
  };

  /**
   * Creates a new instance from a {@link http://en.wikipedia.org/wiki/ISO_8601|ISO 8601} interval.
   *
   * @throws DeveloperError if options.iso8601 does not match proper formatting.
   *
   * @param {Object} options Object with the following properties:
   * @param {String} options.iso8601 An ISO 8601 interval.
   * @param {Boolean} [options.isStartIncluded=true] <code>true</code> if <code>options.start</code> is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded=true] <code>true</code> if <code>options.stop</code> is included in the interval, <code>false</code> otherwise.
   * @param {Object} [options.data] Arbitrary data associated with this interval.
   * @param {TimeInterval} [result] An existing instance to use for the result.
   * @returns {TimeInterval} The modified result parameter or a new instance if none was provided.
   */
  TimeInterval.fromIso8601 = function (options, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.string("options.iso8601", options.iso8601);
    //>>includeEnd('debug');

    var dates = options.iso8601.split("/");
    if (dates.length !== 2) {
      throw new DeveloperError(
        "options.iso8601 is an invalid ISO 8601 interval."
      );
    }
    var start = JulianDate.fromIso8601(dates[0]);
    var stop = JulianDate.fromIso8601(dates[1]);
    var isStartIncluded = defaultValue(options.isStartIncluded, true);
    var isStopIncluded = defaultValue(options.isStopIncluded, true);
    var data = options.data;

    if (!defined(result)) {
      scratchInterval.start = start;
      scratchInterval.stop = stop;
      scratchInterval.isStartIncluded = isStartIncluded;
      scratchInterval.isStopIncluded = isStopIncluded;
      scratchInterval.data = data;
      return new TimeInterval(scratchInterval);
    }

    result.start = start;
    result.stop = stop;
    result.isStartIncluded = isStartIncluded;
    result.isStopIncluded = isStopIncluded;
    result.data = data;
    return result;
  };

  /**
   * Creates an ISO8601 representation of the provided interval.
   *
   * @param {TimeInterval} timeInterval The interval to be converted.
   * @param {Number} [precision] The number of fractional digits used to represent the seconds component.  By default, the most precise representation is used.
   * @returns {String} The ISO8601 representation of the provided interval.
   */
  TimeInterval.toIso8601 = function (timeInterval, precision) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("timeInterval", timeInterval);
    //>>includeEnd('debug');

    return (
      JulianDate.toIso8601(timeInterval.start, precision) +
      "/" +
      JulianDate.toIso8601(timeInterval.stop, precision)
    );
  };

  /**
   * Duplicates the provided instance.
   *
   * @param {TimeInterval} [timeInterval] The instance to clone.
   * @param {TimeInterval} [result] An existing instance to use for the result.
   * @returns {TimeInterval} The modified result parameter or a new instance if none was provided.
   */
  TimeInterval.clone = function (timeInterval, result) {
    if (!defined(timeInterval)) {
      return undefined;
    }
    if (!defined(result)) {
      return new TimeInterval(timeInterval);
    }
    result.start = timeInterval.start;
    result.stop = timeInterval.stop;
    result.isStartIncluded = timeInterval.isStartIncluded;
    result.isStopIncluded = timeInterval.isStopIncluded;
    result.data = timeInterval.data;
    return result;
  };

  /**
   * Compares two instances and returns <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {TimeInterval} [left] The first instance.
   * @param {TimeInterval} [right] The second instance.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   * @returns {Boolean} <code>true</code> if the dates are equal; otherwise, <code>false</code>.
   */
  TimeInterval.equals = function (left, right, dataComparer) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        ((left.isEmpty && right.isEmpty) ||
          (left.isStartIncluded === right.isStartIncluded &&
            left.isStopIncluded === right.isStopIncluded &&
            JulianDate.equals(left.start, right.start) &&
            JulianDate.equals(left.stop, right.stop) &&
            (left.data === right.data ||
              (defined(dataComparer) && dataComparer(left.data, right.data))))))
    );
  };

  /**
   * Compares two instances and returns <code>true</code> if they are within <code>epsilon</code> seconds of
   * each other.  That is, in order for the dates to be considered equal (and for
   * this function to return <code>true</code>), the absolute value of the difference between them, in
   * seconds, must be less than <code>epsilon</code>.
   *
   * @param {TimeInterval} [left] The first instance.
   * @param {TimeInterval} [right] The second instance.
   * @param {Number} [epsilon=0] The maximum number of seconds that should separate the two instances.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   * @returns {Boolean} <code>true</code> if the two dates are within <code>epsilon</code> seconds of each other; otherwise <code>false</code>.
   */
  TimeInterval.equalsEpsilon = function (left, right, epsilon, dataComparer) {
    epsilon = defaultValue(epsilon, 0);

    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        ((left.isEmpty && right.isEmpty) ||
          (left.isStartIncluded === right.isStartIncluded &&
            left.isStopIncluded === right.isStopIncluded &&
            JulianDate.equalsEpsilon(left.start, right.start, epsilon) &&
            JulianDate.equalsEpsilon(left.stop, right.stop, epsilon) &&
            (left.data === right.data ||
              (defined(dataComparer) && dataComparer(left.data, right.data))))))
    );
  };

  /**
   * Computes the intersection of two intervals, optionally merging their data.
   *
   * @param {TimeInterval} left The first interval.
   * @param {TimeInterval} [right] The second interval.
   * @param {TimeInterval} [result] An existing instance to use for the result.
   * @param {TimeInterval.MergeCallback} [mergeCallback] A function which merges the data of the two intervals. If omitted, the data from the left interval will be used.
   * @returns {TimeInterval} The modified result parameter.
   */
  TimeInterval.intersect = function (left, right, result, mergeCallback) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("left", left);
    //>>includeEnd('debug');

    if (!defined(right)) {
      return TimeInterval.clone(TimeInterval.EMPTY, result);
    }

    var leftStart = left.start;
    var leftStop = left.stop;

    var rightStart = right.start;
    var rightStop = right.stop;

    var intersectsStartRight =
      JulianDate.greaterThanOrEquals(rightStart, leftStart) &&
      JulianDate.greaterThanOrEquals(leftStop, rightStart);
    var intersectsStartLeft =
      !intersectsStartRight &&
      JulianDate.lessThanOrEquals(rightStart, leftStart) &&
      JulianDate.lessThanOrEquals(leftStart, rightStop);

    if (!intersectsStartRight && !intersectsStartLeft) {
      return TimeInterval.clone(TimeInterval.EMPTY, result);
    }

    var leftIsStartIncluded = left.isStartIncluded;
    var leftIsStopIncluded = left.isStopIncluded;
    var rightIsStartIncluded = right.isStartIncluded;
    var rightIsStopIncluded = right.isStopIncluded;
    var leftLessThanRight = JulianDate.lessThan(leftStop, rightStop);

    if (!defined(result)) {
      result = new TimeInterval();
    }

    result.start = intersectsStartRight ? rightStart : leftStart;
    result.isStartIncluded =
      (leftIsStartIncluded && rightIsStartIncluded) ||
      (!JulianDate.equals(rightStart, leftStart) &&
        ((intersectsStartRight && rightIsStartIncluded) ||
          (intersectsStartLeft && leftIsStartIncluded)));
    result.stop = leftLessThanRight ? leftStop : rightStop;
    result.isStopIncluded = leftLessThanRight
      ? leftIsStopIncluded
      : (leftIsStopIncluded && rightIsStopIncluded) ||
        (!JulianDate.equals(rightStop, leftStop) && rightIsStopIncluded);
    result.data = defined(mergeCallback)
      ? mergeCallback(left.data, right.data)
      : left.data;
    return result;
  };

  /**
   * Checks if the specified date is inside the provided interval.
   *
   * @param {TimeInterval} timeInterval The interval.
   * @param {JulianDate} julianDate The date to check.
   * @returns {Boolean} <code>true</code> if the interval contains the specified date, <code>false</code> otherwise.
   */
  TimeInterval.contains = function (timeInterval, julianDate) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("timeInterval", timeInterval);
    Check.typeOf.object("julianDate", julianDate);
    //>>includeEnd('debug');

    if (timeInterval.isEmpty) {
      return false;
    }

    var startComparedToDate = JulianDate.compare(timeInterval.start, julianDate);
    if (startComparedToDate === 0) {
      return timeInterval.isStartIncluded;
    }

    var dateComparedToStop = JulianDate.compare(julianDate, timeInterval.stop);
    if (dateComparedToStop === 0) {
      return timeInterval.isStopIncluded;
    }

    return startComparedToDate < 0 && dateComparedToStop < 0;
  };

  /**
   * Duplicates this instance.
   *
   * @param {TimeInterval} [result] An existing instance to use for the result.
   * @returns {TimeInterval} The modified result parameter or a new instance if none was provided.
   */
  TimeInterval.prototype.clone = function (result) {
    return TimeInterval.clone(this, result);
  };

  /**
   * Compares this instance against the provided instance componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {TimeInterval} [right] The right hand side interval.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  TimeInterval.prototype.equals = function (right, dataComparer) {
    return TimeInterval.equals(this, right, dataComparer);
  };

  /**
   * Compares this instance against the provided instance componentwise and returns
   * <code>true</code> if they are within the provided epsilon,
   * <code>false</code> otherwise.
   *
   * @param {TimeInterval} [right] The right hand side interval.
   * @param {Number} [epsilon=0] The epsilon to use for equality testing.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   * @returns {Boolean} <code>true</code> if they are within the provided epsilon, <code>false</code> otherwise.
   */
  TimeInterval.prototype.equalsEpsilon = function (right, epsilon, dataComparer) {
    return TimeInterval.equalsEpsilon(this, right, epsilon, dataComparer);
  };

  /**
   * Creates a string representing this TimeInterval in ISO8601 format.
   *
   * @returns {String} A string representing this TimeInterval in ISO8601 format.
   */
  TimeInterval.prototype.toString = function () {
    return TimeInterval.toIso8601(this);
  };

  /**
   * An immutable empty interval.
   *
   * @type {TimeInterval}
   * @constant
   */
  TimeInterval.EMPTY = Object.freeze(
    new TimeInterval({
      start: new JulianDate(),
      stop: new JulianDate(),
      isStartIncluded: false,
      isStopIncluded: false,
    })
  );

  var MINIMUM_VALUE = Object.freeze(
    JulianDate.fromIso8601("0000-01-01T00:00:00Z")
  );
  var MAXIMUM_VALUE = Object.freeze(
    JulianDate.fromIso8601("9999-12-31T24:00:00Z")
  );
  var MAXIMUM_INTERVAL = Object.freeze(
    new TimeInterval({
      start: MINIMUM_VALUE,
      stop: MAXIMUM_VALUE,
    })
  );

  /**
   * Constants related to ISO8601 support.
   *
   * @namespace
   *
   * @see {@link http://en.wikipedia.org/wiki/ISO_8601|ISO 8601 on Wikipedia}
   * @see JulianDate
   * @see TimeInterval
   */
  var Iso8601 = {
    /**
     * A {@link JulianDate} representing the earliest time representable by an ISO8601 date.
     * This is equivalent to the date string '0000-01-01T00:00:00Z'
     *
     * @type {JulianDate}
     * @constant
     */
    MINIMUM_VALUE: MINIMUM_VALUE,

    /**
     * A {@link JulianDate} representing the latest time representable by an ISO8601 date.
     * This is equivalent to the date string '9999-12-31T24:00:00Z'
     *
     * @type {JulianDate}
     * @constant
     */
    MAXIMUM_VALUE: MAXIMUM_VALUE,

    /**
     * A {@link TimeInterval} representing the largest interval representable by an ISO8601 interval.
     * This is equivalent to the interval string '0000-01-01T00:00:00Z/9999-12-31T24:00:00Z'
     *
     * @type {JulianDate}
     * @constant
     */
    MAXIMUM_INTERVAL: MAXIMUM_INTERVAL,
  };

  /**
   * This enumerated type is for representing keyboard modifiers. These are keys
   * that are held down in addition to other event types.
   *
   * @enum {Number}
   */
  var KeyboardEventModifier = {
    /**
     * Represents the shift key being held down.
     *
     * @type {Number}
     * @constant
     */
    SHIFT: 0,

    /**
     * Represents the control key being held down.
     *
     * @type {Number}
     * @constant
     */
    CTRL: 1,

    /**
     * Represents the alt key being held down.
     *
     * @type {Number}
     * @constant
     */
    ALT: 2,
  };
  var KeyboardEventModifier$1 = Object.freeze(KeyboardEventModifier);

  /**
   * An {@link InterpolationAlgorithm} for performing Lagrange interpolation.
   *
   * @namespace LagrangePolynomialApproximation
   */
  var LagrangePolynomialApproximation = {
    type: "Lagrange",
  };

  /**
   * Given the desired degree, returns the number of data points required for interpolation.
   *
   * @param {Number} degree The desired degree of interpolation.
   * @returns {Number} The number of required data points needed for the desired degree of interpolation.
   */
  LagrangePolynomialApproximation.getRequiredDataPoints = function (degree) {
    return Math.max(degree + 1.0, 2);
  };

  /**
   * Interpolates values using Lagrange Polynomial Approximation.
   *
   * @param {Number} x The independent variable for which the dependent variables will be interpolated.
   * @param {Number[]} xTable The array of independent variables to use to interpolate.  The values
   * in this array must be in increasing order and the same value must not occur twice in the array.
   * @param {Number[]} yTable The array of dependent variables to use to interpolate.  For a set of three
   * dependent values (p,q,w) at time 1 and time 2 this should be as follows: {p1, q1, w1, p2, q2, w2}.
   * @param {Number} yStride The number of dependent variable values in yTable corresponding to
   * each independent variable value in xTable.
   * @param {Number[]} [result] An existing array into which to store the result.
   * @returns {Number[]} The array of interpolated values, or the result parameter if one was provided.
   */
  LagrangePolynomialApproximation.interpolateOrderZero = function (
    x,
    xTable,
    yTable,
    yStride,
    result
  ) {
    if (!defined(result)) {
      result = new Array(yStride);
    }

    var i;
    var j;
    var length = xTable.length;

    for (i = 0; i < yStride; i++) {
      result[i] = 0;
    }

    for (i = 0; i < length; i++) {
      var coefficient = 1;

      for (j = 0; j < length; j++) {
        if (j !== i) {
          var diffX = xTable[i] - xTable[j];
          coefficient *= (x - xTable[j]) / diffX;
        }
      }

      for (j = 0; j < yStride; j++) {
        result[j] += coefficient * yTable[i * yStride + j];
      }
    }

    return result;
  };

  /**
   * An {@link InterpolationAlgorithm} for performing linear interpolation.
   *
   * @namespace LinearApproximation
   */
  var LinearApproximation = {
    type: "Linear",
  };

  /**
   * Given the desired degree, returns the number of data points required for interpolation.
   * Since linear interpolation can only generate a first degree polynomial, this function
   * always returns 2.
   * @param {Number} degree The desired degree of interpolation.
   * @returns {Number} This function always returns 2.
   *
   */
  LinearApproximation.getRequiredDataPoints = function (degree) {
    return 2;
  };

  /**
   * Interpolates values using linear approximation.
   *
   * @param {Number} x The independent variable for which the dependent variables will be interpolated.
   * @param {Number[]} xTable The array of independent variables to use to interpolate.  The values
   * in this array must be in increasing order and the same value must not occur twice in the array.
   * @param {Number[]} yTable The array of dependent variables to use to interpolate.  For a set of three
   * dependent values (p,q,w) at time 1 and time 2 this should be as follows: {p1, q1, w1, p2, q2, w2}.
   * @param {Number} yStride The number of dependent variable values in yTable corresponding to
   * each independent variable value in xTable.
   * @param {Number[]} [result] An existing array into which to store the result.
   * @returns {Number[]} The array of interpolated values, or the result parameter if one was provided.
   */
  LinearApproximation.interpolateOrderZero = function (
    x,
    xTable,
    yTable,
    yStride,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (xTable.length !== 2) {
      throw new DeveloperError(
        "The xTable provided to the linear interpolator must have exactly two elements."
      );
    } else if (yStride <= 0) {
      throw new DeveloperError(
        "There must be at least 1 dependent variable for each independent variable."
      );
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Array(yStride);
    }

    var i;
    var y0;
    var y1;
    var x0 = xTable[0];
    var x1 = xTable[1];

    //>>includeStart('debug', pragmas.debug);
    if (x0 === x1) {
      throw new DeveloperError(
        "Divide by zero error: xTable[0] and xTable[1] are equal"
      );
    }
    //>>includeEnd('debug');

    for (i = 0; i < yStride; i++) {
      y0 = yTable[i];
      y1 = yTable[i + yStride];
      result[i] = ((y1 - y0) * x + x1 * y0 - x0 * y1) / (x1 - x0);
    }

    return result;
  };

  /**
   * A wrapper around arrays so that the internal length of the array can be manually managed.
   *
   * @alias ManagedArray
   * @constructor
   * @private
   *
   * @param {Number} [length=0] The initial length of the array.
   */
  function ManagedArray(length) {
    length = defaultValue(length, 0);
    this._array = new Array(length);
    this._length = length;
  }

  Object.defineProperties(ManagedArray.prototype, {
    /**
     * Gets or sets the length of the array.
     * If the set length is greater than the length of the internal array, the internal array is resized.
     *
     * @memberof ManagedArray.prototype
     * @type Number
     */
    length: {
      get: function () {
        return this._length;
      },
      set: function (length) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("length", length, 0);
        //>>includeEnd('debug');
        var array = this._array;
        var originalLength = this._length;
        if (length < originalLength) {
          // Remove trailing references
          for (var i = length; i < originalLength; ++i) {
            array[i] = undefined;
          }
        } else if (length > array.length) {
          array.length = length;
        }
        this._length = length;
      },
    },

    /**
     * Gets the internal array.
     *
     * @memberof ManagedArray.prototype
     * @type Array
     * @readonly
     */
    values: {
      get: function () {
        return this._array;
      },
    },
  });

  /**
   * Gets the element at an index.
   *
   * @param {Number} index The index to get.
   */
  ManagedArray.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.lessThan("index", index, this._array.length);
    //>>includeEnd('debug');

    return this._array[index];
  };

  /**
   * Sets the element at an index. Resizes the array if index is greater than the length of the array.
   *
   * @param {Number} index The index to set.
   * @param {*} element The element to set at index.
   */
  ManagedArray.prototype.set = function (index, element) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("index", index);
    //>>includeEnd('debug');

    if (index >= this._length) {
      this.length = index + 1;
    }
    this._array[index] = element;
  };

  /**
   * Returns the last element in the array without modifying the array.
   *
   * @returns {*} The last element in the array.
   */
  ManagedArray.prototype.peek = function () {
    return this._array[this._length - 1];
  };

  /**
   * Push an element into the array.
   *
   * @param {*} element The element to push.
   */
  ManagedArray.prototype.push = function (element) {
    var index = this.length++;
    this._array[index] = element;
  };

  /**
   * Pop an element from the array.
   *
   * @returns {*} The last element in the array.
   */
  ManagedArray.prototype.pop = function () {
    if (this._length === 0) {
      return undefined;
    }
    var element = this._array[this._length - 1];
    --this.length;
    return element;
  };

  /**
   * Resize the internal array if length > _array.length.
   *
   * @param {Number} length The length.
   */
  ManagedArray.prototype.reserve = function (length) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("length", length, 0);
    //>>includeEnd('debug');

    if (length > this._array.length) {
      this._array.length = length;
    }
  };

  /**
   * Resize the array.
   *
   * @param {Number} length The length.
   */
  ManagedArray.prototype.resize = function (length) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("length", length, 0);
    //>>includeEnd('debug');

    this.length = length;
  };

  /**
   * Trim the internal array to the specified length. Defaults to the current length.
   *
   * @param {Number} [length] The length.
   */
  ManagedArray.prototype.trim = function (length) {
    length = defaultValue(length, this._length);
    this._array.length = length;
  };

  /**
   * Defines how geodetic ellipsoid coordinates ({@link Cartographic}) project to a
   * flat map like Cesium's 2D and Columbus View modes.
   *
   * @alias MapProjection
   * @constructor
   *
   * @see GeographicProjection
   * @see WebMercatorProjection
   */
  function MapProjection() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(MapProjection.prototype, {
    /**
     * Gets the {@link Ellipsoid}.
     *
     * @memberof MapProjection.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Projects {@link Cartographic} coordinates, in radians, to projection-specific map coordinates, in meters.
   *
   * @memberof MapProjection
   * @function
   *
   * @param {Cartographic} cartographic The coordinates to project.
   * @param {Cartesian3} [result] An instance into which to copy the result.  If this parameter is
   *        undefined, a new instance is created and returned.
   * @returns {Cartesian3} The projected coordinates.  If the result parameter is not undefined, the
   *          coordinates are copied there and that instance is returned.  Otherwise, a new instance is
   *          created and returned.
   */
  MapProjection.prototype.project = DeveloperError.throwInstantiationError;

  /**
   * Unprojects projection-specific map {@link Cartesian3} coordinates, in meters, to {@link Cartographic}
   * coordinates, in radians.
   *
   * @memberof MapProjection
   * @function
   *
   * @param {Cartesian3} cartesian The Cartesian position to unproject with height (z) in meters.
   * @param {Cartographic} [result] An instance into which to copy the result.  If this parameter is
   *        undefined, a new instance is created and returned.
   * @returns {Cartographic} The unprojected coordinates.  If the result parameter is not undefined, the
   *          coordinates are copied there and that instance is returned.  Otherwise, a new instance is
   *          created and returned.
   */
  MapProjection.prototype.unproject = DeveloperError.throwInstantiationError;

  var defaultAccessToken$1;

  /**
   * @namespace MapboxApi
   */
  var MapboxApi = {};

  Object.defineProperties(MapboxApi, {
    /**
     * The default Mapbox API access token to use if one is not provided to the
     * constructor of an object that uses the Mapbox API.  If this property is undefined,
     * Cesium's default access token is used, which is only suitable for use early in development.
     * Please supply your own access token as soon as possible and prior to deployment.
     * Visit {@link https://www.mapbox.com/help/create-api-access-token/} for details.
     * When Cesium's default access token is used, a message is printed to the console the first
     * time the Mapbox API is used.
     *
     * @type {String}
     * @memberof MapboxApi
     * @deprecated
     */
    defaultAccessToken: {
      set: function (value) {
        defaultAccessToken$1 = value;
        deprecationWarning(
          "mapbox-token",
          "MapboxApi.defaultAccessToken is deprecated and will be removed in CesiumJS 1.73. Pass your access token directly to the MapboxImageryProvider or MapboxStyleImageryProvider constructors."
        );
      },
      get: function () {
        return defaultAccessToken$1;
      },
    },
  });

  MapboxApi.getAccessToken = function (providedToken) {
    if (defined(providedToken)) {
      return providedToken;
    }

    return MapboxApi.defaultAccessToken;
  };

  /**
   * Represents a scalar value's lower and upper bound at a near distance and far distance in eye space.
   * @alias NearFarScalar
   * @constructor
   *
   * @param {Number} [near=0.0] The lower bound of the camera range.
   * @param {Number} [nearValue=0.0] The value at the lower bound of the camera range.
   * @param {Number} [far=1.0] The upper bound of the camera range.
   * @param {Number} [farValue=0.0] The value at the upper bound of the camera range.
   *
   * @see Packable
   */
  function NearFarScalar(near, nearValue, far, farValue) {
    /**
     * The lower bound of the camera range.
     * @type {Number}
     * @default 0.0
     */
    this.near = defaultValue(near, 0.0);
    /**
     * The value at the lower bound of the camera range.
     * @type {Number}
     * @default 0.0
     */
    this.nearValue = defaultValue(nearValue, 0.0);
    /**
     * The upper bound of the camera range.
     * @type {Number}
     * @default 1.0
     */
    this.far = defaultValue(far, 1.0);
    /**
     * The value at the upper bound of the camera range.
     * @type {Number}
     * @default 0.0
     */
    this.farValue = defaultValue(farValue, 0.0);
  }

  /**
   * Duplicates a NearFarScalar instance.
   *
   * @param {NearFarScalar} nearFarScalar The NearFarScalar to duplicate.
   * @param {NearFarScalar} [result] The object onto which to store the result.
   * @returns {NearFarScalar} The modified result parameter or a new NearFarScalar instance if one was not provided. (Returns undefined if nearFarScalar is undefined)
   */
  NearFarScalar.clone = function (nearFarScalar, result) {
    if (!defined(nearFarScalar)) {
      return undefined;
    }

    if (!defined(result)) {
      return new NearFarScalar(
        nearFarScalar.near,
        nearFarScalar.nearValue,
        nearFarScalar.far,
        nearFarScalar.farValue
      );
    }

    result.near = nearFarScalar.near;
    result.nearValue = nearFarScalar.nearValue;
    result.far = nearFarScalar.far;
    result.farValue = nearFarScalar.farValue;
    return result;
  };

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  NearFarScalar.packedLength = 4;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {NearFarScalar} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  NearFarScalar.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    array[startingIndex++] = value.near;
    array[startingIndex++] = value.nearValue;
    array[startingIndex++] = value.far;
    array[startingIndex] = value.farValue;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {NearFarScalar} [result] The object into which to store the result.
   * @returns {NearFarScalar} The modified result parameter or a new NearFarScalar instance if one was not provided.
   */
  NearFarScalar.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    if (!defined(result)) {
      result = new NearFarScalar();
    }
    result.near = array[startingIndex++];
    result.nearValue = array[startingIndex++];
    result.far = array[startingIndex++];
    result.farValue = array[startingIndex];
    return result;
  };

  /**
   * Compares the provided NearFarScalar and returns <code>true</code> if they are equal,
   * <code>false</code> otherwise.
   *
   * @param {NearFarScalar} [left] The first NearFarScalar.
   * @param {NearFarScalar} [right] The second NearFarScalar.
   * @returns {Boolean} <code>true</code> if left and right are equal; otherwise <code>false</code>.
   */
  NearFarScalar.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.near === right.near &&
        left.nearValue === right.nearValue &&
        left.far === right.far &&
        left.farValue === right.farValue)
    );
  };

  /**
   * Duplicates this instance.
   *
   * @param {NearFarScalar} [result] The object onto which to store the result.
   * @returns {NearFarScalar} The modified result parameter or a new NearFarScalar instance if one was not provided.
   */
  NearFarScalar.prototype.clone = function (result) {
    return NearFarScalar.clone(this, result);
  };

  /**
   * Compares this instance to the provided NearFarScalar and returns <code>true</code> if they are equal,
   * <code>false</code> otherwise.
   *
   * @param {NearFarScalar} [right] The right hand side NearFarScalar.
   * @returns {Boolean} <code>true</code> if left and right are equal; otherwise <code>false</code>.
   */
  NearFarScalar.prototype.equals = function (right) {
    return NearFarScalar.equals(this, right);
  };

  /**
   * This enumerated type is used in determining to what extent an object, the occludee,
   * is visible during horizon culling. An occluder may fully block an occludee, in which case
   * it has no visibility, may partially block an occludee from view, or may not block it at all,
   * leading to full visibility.
   *
   * @enum {Number}
   */
  var Visibility = {
    /**
     * Represents that no part of an object is visible.
     *
     * @type {Number}
     * @constant
     */
    NONE: -1,

    /**
     * Represents that part, but not all, of an object is visible
     *
     * @type {Number}
     * @constant
     */
    PARTIAL: 0,

    /**
     * Represents that an object is visible in its entirety.
     *
     * @type {Number}
     * @constant
     */
    FULL: 1,
  };
  var Visibility$1 = Object.freeze(Visibility);

  /**
   * Creates an Occluder derived from an object's position and radius, as well as the camera position.
   * The occluder can be used to determine whether or not other objects are visible or hidden behind the
   * visible horizon defined by the occluder and camera position.
   *
   * @alias Occluder
   *
   * @param {BoundingSphere} occluderBoundingSphere The bounding sphere surrounding the occluder.
   * @param {Cartesian3} cameraPosition The coordinate of the viewer/camera.
   *
   * @constructor
   *
   * @example
   * // Construct an occluder one unit away from the origin with a radius of one.
   * var cameraPosition = Cesium.Cartesian3.ZERO;
   * var occluderBoundingSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 1);
   * var occluder = new Cesium.Occluder(occluderBoundingSphere, cameraPosition);
   */
  function Occluder(occluderBoundingSphere, cameraPosition) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(occluderBoundingSphere)) {
      throw new DeveloperError("occluderBoundingSphere is required.");
    }
    if (!defined(cameraPosition)) {
      throw new DeveloperError("camera position is required.");
    }
    //>>includeEnd('debug');

    this._occluderPosition = Cartesian3.clone(occluderBoundingSphere.center);
    this._occluderRadius = occluderBoundingSphere.radius;

    this._horizonDistance = 0.0;
    this._horizonPlaneNormal = undefined;
    this._horizonPlanePosition = undefined;
    this._cameraPosition = undefined;

    // cameraPosition fills in the above values
    this.cameraPosition = cameraPosition;
  }

  var scratchCartesian3$7 = new Cartesian3();

  Object.defineProperties(Occluder.prototype, {
    /**
     * The position of the occluder.
     * @memberof Occluder.prototype
     * @type {Cartesian3}
     */
    position: {
      get: function () {
        return this._occluderPosition;
      },
    },

    /**
     * The radius of the occluder.
     * @memberof Occluder.prototype
     * @type {Number}
     */
    radius: {
      get: function () {
        return this._occluderRadius;
      },
    },

    /**
     * The position of the camera.
     * @memberof Occluder.prototype
     * @type {Cartesian3}
     */
    cameraPosition: {
      set: function (cameraPosition) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(cameraPosition)) {
          throw new DeveloperError("cameraPosition is required.");
        }
        //>>includeEnd('debug');

        cameraPosition = Cartesian3.clone(cameraPosition, this._cameraPosition);

        var cameraToOccluderVec = Cartesian3.subtract(
          this._occluderPosition,
          cameraPosition,
          scratchCartesian3$7
        );
        var invCameraToOccluderDistance = Cartesian3.magnitudeSquared(
          cameraToOccluderVec
        );
        var occluderRadiusSqrd = this._occluderRadius * this._occluderRadius;

        var horizonDistance;
        var horizonPlaneNormal;
        var horizonPlanePosition;
        if (invCameraToOccluderDistance > occluderRadiusSqrd) {
          horizonDistance = Math.sqrt(
            invCameraToOccluderDistance - occluderRadiusSqrd
          );
          invCameraToOccluderDistance =
            1.0 / Math.sqrt(invCameraToOccluderDistance);
          horizonPlaneNormal = Cartesian3.multiplyByScalar(
            cameraToOccluderVec,
            invCameraToOccluderDistance,
            scratchCartesian3$7
          );
          var nearPlaneDistance =
            horizonDistance * horizonDistance * invCameraToOccluderDistance;
          horizonPlanePosition = Cartesian3.add(
            cameraPosition,
            Cartesian3.multiplyByScalar(
              horizonPlaneNormal,
              nearPlaneDistance,
              scratchCartesian3$7
            ),
            scratchCartesian3$7
          );
        } else {
          horizonDistance = Number.MAX_VALUE;
        }

        this._horizonDistance = horizonDistance;
        this._horizonPlaneNormal = horizonPlaneNormal;
        this._horizonPlanePosition = horizonPlanePosition;
        this._cameraPosition = cameraPosition;
      },
    },
  });

  /**
   * Creates an occluder from a bounding sphere and the camera position.
   *
   * @param {BoundingSphere} occluderBoundingSphere The bounding sphere surrounding the occluder.
   * @param {Cartesian3} cameraPosition The coordinate of the viewer/camera.
   * @param {Occluder} [result] The object onto which to store the result.
   * @returns {Occluder} The occluder derived from an object's position and radius, as well as the camera position.
   */
  Occluder.fromBoundingSphere = function (
    occluderBoundingSphere,
    cameraPosition,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(occluderBoundingSphere)) {
      throw new DeveloperError("occluderBoundingSphere is required.");
    }

    if (!defined(cameraPosition)) {
      throw new DeveloperError("camera position is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Occluder(occluderBoundingSphere, cameraPosition);
    }

    Cartesian3.clone(occluderBoundingSphere.center, result._occluderPosition);
    result._occluderRadius = occluderBoundingSphere.radius;
    result.cameraPosition = cameraPosition;

    return result;
  };

  var tempVecScratch = new Cartesian3();

  /**
   * Determines whether or not a point, the <code>occludee</code>, is hidden from view by the occluder.
   *
   * @param {Cartesian3} occludee The point surrounding the occludee object.
   * @returns {Boolean} <code>true</code> if the occludee is visible; otherwise <code>false</code>.
   *
   *
   * @example
   * var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
   * var littleSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 0.25);
   * var occluder = new Cesium.Occluder(littleSphere, cameraPosition);
   * var point = new Cesium.Cartesian3(0, 0, -3);
   * occluder.isPointVisible(point); //returns true
   *
   * @see Occluder#computeVisibility
   */
  Occluder.prototype.isPointVisible = function (occludee) {
    if (this._horizonDistance !== Number.MAX_VALUE) {
      var tempVec = Cartesian3.subtract(
        occludee,
        this._occluderPosition,
        tempVecScratch
      );
      var temp = this._occluderRadius;
      temp = Cartesian3.magnitudeSquared(tempVec) - temp * temp;
      if (temp > 0.0) {
        temp = Math.sqrt(temp) + this._horizonDistance;
        tempVec = Cartesian3.subtract(occludee, this._cameraPosition, tempVec);
        return temp * temp > Cartesian3.magnitudeSquared(tempVec);
      }
    }
    return false;
  };

  var occludeePositionScratch = new Cartesian3();

  /**
   * Determines whether or not a sphere, the <code>occludee</code>, is hidden from view by the occluder.
   *
   * @param {BoundingSphere} occludee The bounding sphere surrounding the occludee object.
   * @returns {Boolean} <code>true</code> if the occludee is visible; otherwise <code>false</code>.
   *
   *
   * @example
   * var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
   * var littleSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 0.25);
   * var occluder = new Cesium.Occluder(littleSphere, cameraPosition);
   * var bigSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -3), 1);
   * occluder.isBoundingSphereVisible(bigSphere); //returns true
   *
   * @see Occluder#computeVisibility
   */
  Occluder.prototype.isBoundingSphereVisible = function (occludee) {
    var occludeePosition = Cartesian3.clone(
      occludee.center,
      occludeePositionScratch
    );
    var occludeeRadius = occludee.radius;

    if (this._horizonDistance !== Number.MAX_VALUE) {
      var tempVec = Cartesian3.subtract(
        occludeePosition,
        this._occluderPosition,
        tempVecScratch
      );
      var temp = this._occluderRadius - occludeeRadius;
      temp = Cartesian3.magnitudeSquared(tempVec) - temp * temp;
      if (occludeeRadius < this._occluderRadius) {
        if (temp > 0.0) {
          temp = Math.sqrt(temp) + this._horizonDistance;
          tempVec = Cartesian3.subtract(
            occludeePosition,
            this._cameraPosition,
            tempVec
          );
          return (
            temp * temp + occludeeRadius * occludeeRadius >
            Cartesian3.magnitudeSquared(tempVec)
          );
        }
        return false;
      }

      // Prevent against the case where the occludee radius is larger than the occluder's; since this is
      // an uncommon case, the following code should rarely execute.
      if (temp > 0.0) {
        tempVec = Cartesian3.subtract(
          occludeePosition,
          this._cameraPosition,
          tempVec
        );
        var tempVecMagnitudeSquared = Cartesian3.magnitudeSquared(tempVec);
        var occluderRadiusSquared = this._occluderRadius * this._occluderRadius;
        var occludeeRadiusSquared = occludeeRadius * occludeeRadius;
        if (
          (this._horizonDistance * this._horizonDistance +
            occluderRadiusSquared) *
            occludeeRadiusSquared >
          tempVecMagnitudeSquared * occluderRadiusSquared
        ) {
          // The occludee is close enough that the occluder cannot possible occlude the occludee
          return true;
        }
        temp = Math.sqrt(temp) + this._horizonDistance;
        return temp * temp + occludeeRadiusSquared > tempVecMagnitudeSquared;
      }

      // The occludee completely encompasses the occluder
      return true;
    }

    return false;
  };

  var tempScratch$1 = new Cartesian3();
  /**
   * Determine to what extent an occludee is visible (not visible, partially visible,  or fully visible).
   *
   * @param {BoundingSphere} occludeeBS The bounding sphere of the occludee.
   * @returns {Visibility} Visibility.NONE if the occludee is not visible,
   *                       Visibility.PARTIAL if the occludee is partially visible, or
   *                       Visibility.FULL if the occludee is fully visible.
   *
   *
   * @example
   * var sphere1 = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1.5), 0.5);
   * var sphere2 = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -2.5), 0.5);
   * var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
   * var occluder = new Cesium.Occluder(sphere1, cameraPosition);
   * occluder.computeVisibility(sphere2); //returns Visibility.NONE
   *
   * @see Occluder#isVisible
   */
  Occluder.prototype.computeVisibility = function (occludeeBS) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(occludeeBS)) {
      throw new DeveloperError("occludeeBS is required.");
    }
    //>>includeEnd('debug');

    // If the occludee radius is larger than the occluders, this will return that
    // the entire ocludee is visible, even though that may not be the case, though this should
    // not occur too often.
    var occludeePosition = Cartesian3.clone(occludeeBS.center);
    var occludeeRadius = occludeeBS.radius;

    if (occludeeRadius > this._occluderRadius) {
      return Visibility$1.FULL;
    }

    if (this._horizonDistance !== Number.MAX_VALUE) {
      // The camera is outside the occluder
      var tempVec = Cartesian3.subtract(
        occludeePosition,
        this._occluderPosition,
        tempScratch$1
      );
      var temp = this._occluderRadius - occludeeRadius;
      var occluderToOccludeeDistSqrd = Cartesian3.magnitudeSquared(tempVec);
      temp = occluderToOccludeeDistSqrd - temp * temp;
      if (temp > 0.0) {
        // The occludee is not completely inside the occluder
        // Check to see if the occluder completely hides the occludee
        temp = Math.sqrt(temp) + this._horizonDistance;
        tempVec = Cartesian3.subtract(
          occludeePosition,
          this._cameraPosition,
          tempVec
        );
        var cameraToOccludeeDistSqrd = Cartesian3.magnitudeSquared(tempVec);
        if (
          temp * temp + occludeeRadius * occludeeRadius <
          cameraToOccludeeDistSqrd
        ) {
          return Visibility$1.NONE;
        }

        // Check to see whether the occluder is fully or partially visible
        // when the occludee does not intersect the occluder
        temp = this._occluderRadius + occludeeRadius;
        temp = occluderToOccludeeDistSqrd - temp * temp;
        if (temp > 0.0) {
          // The occludee does not intersect the occluder.
          temp = Math.sqrt(temp) + this._horizonDistance;
          return cameraToOccludeeDistSqrd <
            temp * temp + occludeeRadius * occludeeRadius
            ? Visibility$1.FULL
            : Visibility$1.PARTIAL;
        }

        //Check to see if the occluder is fully or partially visible when the occludee DOES
        //intersect the occluder
        tempVec = Cartesian3.subtract(
          occludeePosition,
          this._horizonPlanePosition,
          tempVec
        );
        return Cartesian3.dot(tempVec, this._horizonPlaneNormal) > -occludeeRadius
          ? Visibility$1.PARTIAL
          : Visibility$1.FULL;
      }
    }
    return Visibility$1.NONE;
  };

  var occludeePointScratch = new Cartesian3();
  /**
   * Computes a point that can be used as the occludee position to the visibility functions.
   * Use a radius of zero for the occludee radius.  Typically, a user computes a bounding sphere around
   * an object that is used for visibility; however it is also possible to compute a point that if
   * seen/not seen would also indicate if an object is visible/not visible.  This function is better
   * called for objects that do not move relative to the occluder and is large, such as a chunk of
   * terrain.  You are better off not calling this and using the object's bounding sphere for objects
   * such as a satellite or ground vehicle.
   *
   * @param {BoundingSphere} occluderBoundingSphere The bounding sphere surrounding the occluder.
   * @param {Cartesian3} occludeePosition The point where the occludee (bounding sphere of radius 0) is located.
   * @param {Cartesian3[]} positions List of altitude points on the horizon near the surface of the occluder.
   * @returns {Object} An object containing two attributes: <code>occludeePoint</code> and <code>valid</code>
   * which is a boolean value.
   *
   * @exception {DeveloperError} <code>positions</code> must contain at least one element.
   * @exception {DeveloperError} <code>occludeePosition</code> must have a value other than <code>occluderBoundingSphere.center</code>.
   *
   * @example
   * var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
   * var occluderBoundingSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -8), 2);
   * var occluder = new Cesium.Occluder(occluderBoundingSphere, cameraPosition);
   * var positions = [new Cesium.Cartesian3(-0.25, 0, -5.3), new Cesium.Cartesian3(0.25, 0, -5.3)];
   * var tileOccluderSphere = Cesium.BoundingSphere.fromPoints(positions);
   * var occludeePosition = tileOccluderSphere.center;
   * var occludeePt = Cesium.Occluder.computeOccludeePoint(occluderBoundingSphere, occludeePosition, positions);
   */
  Occluder.computeOccludeePoint = function (
    occluderBoundingSphere,
    occludeePosition,
    positions
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(occluderBoundingSphere)) {
      throw new DeveloperError("occluderBoundingSphere is required.");
    }
    if (!defined(positions)) {
      throw new DeveloperError("positions is required.");
    }
    if (positions.length === 0) {
      throw new DeveloperError("positions must contain at least one element");
    }
    //>>includeEnd('debug');

    var occludeePos = Cartesian3.clone(occludeePosition);
    var occluderPosition = Cartesian3.clone(occluderBoundingSphere.center);
    var occluderRadius = occluderBoundingSphere.radius;
    var numPositions = positions.length;

    //>>includeStart('debug', pragmas.debug);
    if (Cartesian3.equals(occluderPosition, occludeePosition)) {
      throw new DeveloperError(
        "occludeePosition must be different than occluderBoundingSphere.center"
      );
    }
    //>>includeEnd('debug');

    // Compute a plane with a normal from the occluder to the occludee position.
    var occluderPlaneNormal = Cartesian3.normalize(
      Cartesian3.subtract(occludeePos, occluderPosition, occludeePointScratch),
      occludeePointScratch
    );
    var occluderPlaneD = -Cartesian3.dot(occluderPlaneNormal, occluderPosition);

    //For each position, determine the horizon intersection. Choose the position and intersection
    //that results in the greatest angle with the occcluder plane.
    var aRotationVector = Occluder._anyRotationVector(
      occluderPosition,
      occluderPlaneNormal,
      occluderPlaneD
    );
    var dot = Occluder._horizonToPlaneNormalDotProduct(
      occluderBoundingSphere,
      occluderPlaneNormal,
      occluderPlaneD,
      aRotationVector,
      positions[0]
    );
    if (!dot) {
      //The position is inside the mimimum radius, which is invalid
      return undefined;
    }
    var tempDot;
    for (var i = 1; i < numPositions; ++i) {
      tempDot = Occluder._horizonToPlaneNormalDotProduct(
        occluderBoundingSphere,
        occluderPlaneNormal,
        occluderPlaneD,
        aRotationVector,
        positions[i]
      );
      if (!tempDot) {
        //The position is inside the minimum radius, which is invalid
        return undefined;
      }
      if (tempDot < dot) {
        dot = tempDot;
      }
    }
    //Verify that the dot is not near 90 degress
    if (dot < 0.00174532836589830883577820272085) {
      return undefined;
    }

    var distance = occluderRadius / dot;
    return Cartesian3.add(
      occluderPosition,
      Cartesian3.multiplyByScalar(
        occluderPlaneNormal,
        distance,
        occludeePointScratch
      ),
      occludeePointScratch
    );
  };

  var computeOccludeePointFromRectangleScratch = [];
  /**
   * Computes a point that can be used as the occludee position to the visibility functions from a rectangle.
   *
   * @param {Rectangle} rectangle The rectangle used to create a bounding sphere.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid used to determine positions of the rectangle.
   * @returns {Object} An object containing two attributes: <code>occludeePoint</code> and <code>valid</code>
   * which is a boolean value.
   */
  Occluder.computeOccludeePointFromRectangle = function (rectangle, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(rectangle)) {
      throw new DeveloperError("rectangle is required.");
    }
    //>>includeEnd('debug');

    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    var positions = Rectangle.subsample(
      rectangle,
      ellipsoid,
      0.0,
      computeOccludeePointFromRectangleScratch
    );
    var bs = BoundingSphere.fromPoints(positions);

    // TODO: get correct ellipsoid center
    var ellipsoidCenter = Cartesian3.ZERO;
    if (!Cartesian3.equals(ellipsoidCenter, bs.center)) {
      return Occluder.computeOccludeePoint(
        new BoundingSphere(ellipsoidCenter, ellipsoid.minimumRadius),
        bs.center,
        positions
      );
    }

    return undefined;
  };

  var tempVec0Scratch = new Cartesian3();
  Occluder._anyRotationVector = function (
    occluderPosition,
    occluderPlaneNormal,
    occluderPlaneD
  ) {
    var tempVec0 = Cartesian3.abs(occluderPlaneNormal, tempVec0Scratch);
    var majorAxis = tempVec0.x > tempVec0.y ? 0 : 1;
    if (
      (majorAxis === 0 && tempVec0.z > tempVec0.x) ||
      (majorAxis === 1 && tempVec0.z > tempVec0.y)
    ) {
      majorAxis = 2;
    }
    var tempVec = new Cartesian3();
    var tempVec1;
    if (majorAxis === 0) {
      tempVec0.x = occluderPosition.x;
      tempVec0.y = occluderPosition.y + 1.0;
      tempVec0.z = occluderPosition.z + 1.0;
      tempVec1 = Cartesian3.UNIT_X;
    } else if (majorAxis === 1) {
      tempVec0.x = occluderPosition.x + 1.0;
      tempVec0.y = occluderPosition.y;
      tempVec0.z = occluderPosition.z + 1.0;
      tempVec1 = Cartesian3.UNIT_Y;
    } else {
      tempVec0.x = occluderPosition.x + 1.0;
      tempVec0.y = occluderPosition.y + 1.0;
      tempVec0.z = occluderPosition.z;
      tempVec1 = Cartesian3.UNIT_Z;
    }
    var u =
      (Cartesian3.dot(occluderPlaneNormal, tempVec0) + occluderPlaneD) /
      -Cartesian3.dot(occluderPlaneNormal, tempVec1);
    return Cartesian3.normalize(
      Cartesian3.subtract(
        Cartesian3.add(
          tempVec0,
          Cartesian3.multiplyByScalar(tempVec1, u, tempVec),
          tempVec0
        ),
        occluderPosition,
        tempVec0
      ),
      tempVec0
    );
  };

  var posDirectionScratch = new Cartesian3();
  Occluder._rotationVector = function (
    occluderPosition,
    occluderPlaneNormal,
    occluderPlaneD,
    position,
    anyRotationVector
  ) {
    //Determine the angle between the occluder plane normal and the position direction
    var positionDirection = Cartesian3.subtract(
      position,
      occluderPosition,
      posDirectionScratch
    );
    positionDirection = Cartesian3.normalize(
      positionDirection,
      positionDirection
    );
    if (
      Cartesian3.dot(occluderPlaneNormal, positionDirection) <
      0.99999998476912904932780850903444
    ) {
      var crossProduct = Cartesian3.cross(
        occluderPlaneNormal,
        positionDirection,
        positionDirection
      );
      var length = Cartesian3.magnitude(crossProduct);
      if (length > CesiumMath.EPSILON13) {
        return Cartesian3.normalize(crossProduct, new Cartesian3());
      }
    }
    //The occluder plane normal and the position direction are colinear. Use any
    //vector in the occluder plane as the rotation vector
    return anyRotationVector;
  };

  var posScratch1 = new Cartesian3();
  var occluerPosScratch = new Cartesian3();
  var posScratch2 = new Cartesian3();
  var horizonPlanePosScratch = new Cartesian3();
  Occluder._horizonToPlaneNormalDotProduct = function (
    occluderBS,
    occluderPlaneNormal,
    occluderPlaneD,
    anyRotationVector,
    position
  ) {
    var pos = Cartesian3.clone(position, posScratch1);
    var occluderPosition = Cartesian3.clone(occluderBS.center, occluerPosScratch);
    var occluderRadius = occluderBS.radius;

    //Verify that the position is outside the occluder
    var positionToOccluder = Cartesian3.subtract(
      occluderPosition,
      pos,
      posScratch2
    );
    var occluderToPositionDistanceSquared = Cartesian3.magnitudeSquared(
      positionToOccluder
    );
    var occluderRadiusSquared = occluderRadius * occluderRadius;
    if (occluderToPositionDistanceSquared < occluderRadiusSquared) {
      return false;
    }

    //Horizon parameters
    var horizonDistanceSquared =
      occluderToPositionDistanceSquared - occluderRadiusSquared;
    var horizonDistance = Math.sqrt(horizonDistanceSquared);
    var occluderToPositionDistance = Math.sqrt(occluderToPositionDistanceSquared);
    var invOccluderToPositionDistance = 1.0 / occluderToPositionDistance;
    var cosTheta = horizonDistance * invOccluderToPositionDistance;
    var horizonPlaneDistance = cosTheta * horizonDistance;
    positionToOccluder = Cartesian3.normalize(
      positionToOccluder,
      positionToOccluder
    );
    var horizonPlanePosition = Cartesian3.add(
      pos,
      Cartesian3.multiplyByScalar(
        positionToOccluder,
        horizonPlaneDistance,
        horizonPlanePosScratch
      ),
      horizonPlanePosScratch
    );
    var horizonCrossDistance = Math.sqrt(
      horizonDistanceSquared - horizonPlaneDistance * horizonPlaneDistance
    );

    //Rotate the position to occluder vector 90 degrees
    var tempVec = this._rotationVector(
      occluderPosition,
      occluderPlaneNormal,
      occluderPlaneD,
      pos,
      anyRotationVector
    );
    var horizonCrossDirection = Cartesian3.fromElements(
      tempVec.x * tempVec.x * positionToOccluder.x +
        (tempVec.x * tempVec.y - tempVec.z) * positionToOccluder.y +
        (tempVec.x * tempVec.z + tempVec.y) * positionToOccluder.z,
      (tempVec.x * tempVec.y + tempVec.z) * positionToOccluder.x +
        tempVec.y * tempVec.y * positionToOccluder.y +
        (tempVec.y * tempVec.z - tempVec.x) * positionToOccluder.z,
      (tempVec.x * tempVec.z - tempVec.y) * positionToOccluder.x +
        (tempVec.y * tempVec.z + tempVec.x) * positionToOccluder.y +
        tempVec.z * tempVec.z * positionToOccluder.z,
      posScratch1
    );
    horizonCrossDirection = Cartesian3.normalize(
      horizonCrossDirection,
      horizonCrossDirection
    );

    //Horizon positions
    var offset = Cartesian3.multiplyByScalar(
      horizonCrossDirection,
      horizonCrossDistance,
      posScratch1
    );
    tempVec = Cartesian3.normalize(
      Cartesian3.subtract(
        Cartesian3.add(horizonPlanePosition, offset, posScratch2),
        occluderPosition,
        posScratch2
      ),
      posScratch2
    );
    var dot0 = Cartesian3.dot(occluderPlaneNormal, tempVec);
    tempVec = Cartesian3.normalize(
      Cartesian3.subtract(
        Cartesian3.subtract(horizonPlanePosition, offset, tempVec),
        occluderPosition,
        tempVec
      ),
      tempVec
    );
    var dot1 = Cartesian3.dot(occluderPlaneNormal, tempVec);
    return dot0 < dot1 ? dot0 : dot1;
  };

  /**
   * Value and type information for per-instance geometry attribute that determines the geometry instance offset
   *
   * @alias OffsetGeometryInstanceAttribute
   * @constructor
   *
   * @param {Number} [x=0] The x translation
   * @param {Number} [y=0] The y translation
   * @param {Number} [z=0] The z translation
   *
   * @private
   *
   * @see GeometryInstance
   * @see GeometryInstanceAttribute
   */
  function OffsetGeometryInstanceAttribute(x, y, z) {
    x = defaultValue(x, 0);
    y = defaultValue(y, 0);
    z = defaultValue(z, 0);

    /**
     * The values for the attributes stored in a typed array.
     *
     * @type Float32Array
     */
    this.value = new Float32Array([x, y, z]);
  }

  Object.defineProperties(OffsetGeometryInstanceAttribute.prototype, {
    /**
     * The datatype of each component in the attribute, e.g., individual elements in
     * {@link OffsetGeometryInstanceAttribute#value}.
     *
     * @memberof OffsetGeometryInstanceAttribute.prototype
     *
     * @type {ComponentDatatype}
     * @readonly
     *
     * @default {@link ComponentDatatype.FLOAT}
     */
    componentDatatype: {
      get: function () {
        return ComponentDatatype$1.FLOAT;
      },
    },

    /**
     * The number of components in the attributes, i.e., {@link OffsetGeometryInstanceAttribute#value}.
     *
     * @memberof OffsetGeometryInstanceAttribute.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @default 3
     */
    componentsPerAttribute: {
      get: function () {
        return 3;
      },
    },

    /**
     * When <code>true</code> and <code>componentDatatype</code> is an integer format,
     * indicate that the components should be mapped to the range [0, 1] (unsigned)
     * or [-1, 1] (signed) when they are accessed as floating-point for rendering.
     *
     * @memberof OffsetGeometryInstanceAttribute.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    normalize: {
      get: function () {
        return false;
      },
    },
  });

  /**
   * Creates a new {@link OffsetGeometryInstanceAttribute} instance given the provided an enabled flag and {@link DistanceDisplayCondition}.
   *
   * @param {Cartesian3} offset The cartesian offset
   * @returns {OffsetGeometryInstanceAttribute} The new {@link OffsetGeometryInstanceAttribute} instance.
   */
  OffsetGeometryInstanceAttribute.fromCartesian3 = function (offset) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("offset", offset);
    //>>includeEnd('debug');

    return new OffsetGeometryInstanceAttribute(offset.x, offset.y, offset.z);
  };

  /**
   * Converts a distance display condition to a typed array that can be used to assign a distance display condition attribute.
   *
   * @param {Cartesian3} offset The cartesian offset
   * @param {Float32Array} [result] The array to store the result in, if undefined a new instance will be created.
   * @returns {Float32Array} The modified result parameter or a new instance if result was undefined.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.modelMatrix = Cesium.OffsetGeometryInstanceAttribute.toValue(modelMatrix, attributes.modelMatrix);
   */
  OffsetGeometryInstanceAttribute.toValue = function (offset, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("offset", offset);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Float32Array([offset.x, offset.y, offset.z]);
    }

    result[0] = offset.x;
    result[1] = offset.y;
    result[2] = offset.z;
    return result;
  };

  /**
   * Provides geocoding via a {@link https://opencagedata.com/|OpenCage} server.
   * @alias OpenCageGeocoderService
   * @constructor
   *
   * @param {Resource|String} url The endpoint to the OpenCage server.
   * @param {String} apiKey The OpenCage API Key.
   * @param {Object} [params] An object with the following properties (See https://opencagedata.com/api#forward-opt):
   * @param {Number} [params.abbrv] When set to 1 we attempt to abbreviate and shorten the formatted string we return.
   * @param {Number} [options.add_request] When set to 1 the various request parameters are added to the response for ease of debugging.
   * @param {String} [options.bounds] Provides the geocoder with a hint to the region that the query resides in.
   * @param {String} [options.countrycode] Restricts the results to the specified country or countries (as defined by the ISO 3166-1 Alpha 2 standard).
   * @param {String} [options.jsonp] Wraps the returned JSON with a function name.
   * @param {String} [options.language] An IETF format language code.
   * @param {Number} [options.limit] The maximum number of results we should return.
   * @param {Number} [options.min_confidence] An integer from 1-10. Only results with at least this confidence will be returned.
   * @param {Number} [options.no_annotations] When set to 1 results will not contain annotations.
   * @param {Number} [options.no_dedupe] When set to 1 results will not be deduplicated.
   * @param {Number} [options.no_record] When set to 1 the query contents are not logged.
   * @param {Number} [options.pretty] When set to 1 results are 'pretty' printed for easier reading. Useful for debugging.
   * @param {String} [options.proximity] Provides the geocoder with a hint to bias results in favour of those closer to the specified location (For example: 41.40139,2.12870).
   *
   * @example
   * // Configure a Viewer to use the OpenCage Geocoder
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *   geocoder: new Cesium.OpenCageGeocoderService('https://api.opencagedata.com/geocode/v1/', '<API key>')
   * });
   */
  function OpenCageGeocoderService(url, apiKey, params) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("url", url);
    Check.defined("apiKey", apiKey);
    if (defined(params)) {
      Check.typeOf.object("params", params);
    }
    //>>includeEnd('debug');

    url = Resource.createIfNeeded(url);
    url.appendForwardSlash();
    url.setQueryParameters({ key: apiKey });
    this._url = url;
    this._params = defaultValue(params, {});
  }

  Object.defineProperties(OpenCageGeocoderService.prototype, {
    /**
     * The Resource used to access the OpenCage endpoint.
     * @type {Resource}
     * @memberof OpenCageGeocoderService.prototype
     * @readonly
     */
    url: {
      get: function () {
        return this._url;
      },
    },
    /**
     * Optional params passed to OpenCage in order to customize geocoding
     * @type {Object}
     * @memberof OpenCageGeocoderService.prototype
     * @readonly
     */
    params: {
      get: function () {
        return this._params;
      },
    },
  });

  /**
   * @function
   *
   * @param {String} query The query to be sent to the geocoder service
   * @returns {Promise<GeocoderService.Result[]>}
   */
  OpenCageGeocoderService.prototype.geocode = function (query) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("query", query);
    //>>includeEnd('debug');

    var resource = this._url.getDerivedResource({
      url: "json",
      queryParameters: combine(this._params, { q: query }),
    });
    return resource.fetchJson().then(function (response) {
      return response.results.map(function (resultObject) {
        var destination;
        var bounds = resultObject.bounds;

        if (defined(bounds)) {
          destination = Rectangle.fromDegrees(
            bounds.southwest.lng,
            bounds.southwest.lat,
            bounds.northeast.lng,
            bounds.northeast.lat
          );
        } else {
          var lon = resultObject.geometry.lat;
          var lat = resultObject.geometry.lng;
          destination = Cartesian3.fromDegrees(lon, lat);
        }

        return {
          displayName: resultObject.formatted,
          destination: destination,
        };
      });
    });
  };

  /**
   * Static interface for types which can store their values as packed
   * elements in an array.  These methods and properties are expected to be
   * defined on a constructor function.
   *
   * @interface Packable
   *
   * @see PackableForInterpolation
   */
  var Packable = {
    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    packedLength: undefined,

    /**
     * Stores the provided instance into the provided array.
     * @function
     *
     * @param {*} value The value to pack.
     * @param {Number[]} array The array to pack into.
     * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
     */
    pack: DeveloperError.throwInstantiationError,

    /**
     * Retrieves an instance from a packed array.
     * @function
     *
     * @param {Number[]} array The packed array.
     * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
     * @param {Object} [result] The object into which to store the result.
     * @returns {Object} The modified result parameter or a new Object instance if one was not provided.
     */
    unpack: DeveloperError.throwInstantiationError,
  };

  /**
   * Static interface for {@link Packable} types which are interpolated in a
   * different representation than their packed value.  These methods and
   * properties are expected to be defined on a constructor function.
   *
   * @namespace PackableForInterpolation
   *
   * @see Packable
   */
  var PackableForInterpolation = {
    /**
     * The number of elements used to store the object into an array in its interpolatable form.
     * @type {Number}
     */
    packedInterpolationLength: undefined,

    /**
     * Converts a packed array into a form suitable for interpolation.
     * @function
     *
     * @param {Number[]} packedArray The packed array.
     * @param {Number} [startingIndex=0] The index of the first element to be converted.
     * @param {Number} [lastIndex=packedArray.length] The index of the last element to be converted.
     * @param {Number[]} [result] The object into which to store the result.
     */
    convertPackedArrayForInterpolation: DeveloperError.throwInstantiationError,

    /**
     * Retrieves an instance from a packed array converted with {@link PackableForInterpolation.convertPackedArrayForInterpolation}.
     * @function
     *
     * @param {Number[]} array The array previously packed for interpolation.
     * @param {Number[]} sourceArray The original packed array.
     * @param {Number} [startingIndex=0] The startingIndex used to convert the array.
     * @param {Number} [lastIndex=packedArray.length] The lastIndex used to convert the array.
     * @param {Object} [result] The object into which to store the result.
     * @returns {Object} The modified result parameter or a new Object instance if one was not provided.
     */
    unpackInterpolationResult: DeveloperError.throwInstantiationError,
  };

  /*
    This library rewrites the Canvas2D "measureText" function
    so that it returns a more complete metrics object.

  ** -----------------------------------------------------------------------------

    CHANGELOG:

      2012-01-21 - Whitespace handling added by Joe Turner
                   (https://github.com/oampo)

  ** -----------------------------------------------------------------------------
  */
  /**
    @license
    fontmetrics.js - https://github.com/Pomax/fontmetrics.js

    Copyright (C) 2011 by Mike "Pomax" Kamermans

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    THE SOFTWARE.
  **/

  /*
    var NAME = "FontMetrics Library"
    var VERSION = "1-2012.0121.1300";

    // if there is no getComputedStyle, this library won't work.
    if(!document.defaultView.getComputedStyle) {
      throw("ERROR: 'document.defaultView.getComputedStyle' not found. This library only works in browsers that can report computed CSS values.");
    }

    // store the old text metrics function on the Canvas2D prototype
    CanvasRenderingContext2D.prototype.measureTextWidth = CanvasRenderingContext2D.prototype.measureText;
  */
    /**
     *  shortcut function for getting computed CSS values
     */
    var getCSSValue = function(element, property) {
      return document.defaultView.getComputedStyle(element,null).getPropertyValue(property);
    };
  /*
    // debug function
    var show = function(canvas, ctx, xstart, w, h, metrics)
    {
      document.body.appendChild(canvas);
      ctx.strokeStyle = 'rgba(0, 0, 0, 0.5)';

      ctx.beginPath();
      ctx.moveTo(xstart,0);
      ctx.lineTo(xstart,h);
      ctx.closePath();
      ctx.stroke();

      ctx.beginPath();
      ctx.moveTo(xstart+metrics.bounds.maxx,0);
      ctx.lineTo(xstart+metrics.bounds.maxx,h);
      ctx.closePath();
      ctx.stroke();

      ctx.beginPath();
      ctx.moveTo(0,h/2-metrics.ascent);
      ctx.lineTo(w,h/2-metrics.ascent);
      ctx.closePath();
      ctx.stroke();

      ctx.beginPath();
      ctx.moveTo(0,h/2+metrics.descent);
      ctx.lineTo(w,h/2+metrics.descent);
      ctx.closePath();
      ctx.stroke();
    }
  */
    /**
     * The new text metrics function
     */
    var measureText = function(context2D, textstring, stroke, fill) {
      var metrics = context2D.measureText(textstring),
          fontFamily = getCSSValue(context2D.canvas,"font-family"),
          fontSize = getCSSValue(context2D.canvas,"font-size").replace("px",""),
          fontStyle = getCSSValue(context2D.canvas,"font-style"),
          fontWeight = getCSSValue(context2D.canvas,"font-weight"),
          isSpace = !(/\S/.test(textstring));
          metrics.fontsize = fontSize;

      // for text lead values, we meaure a multiline text container.
      var leadDiv = document.createElement("div");
      leadDiv.style.position = "absolute";
      leadDiv.style.opacity = 0;
      leadDiv.style.font = fontStyle + " " + fontWeight + " " + fontSize + "px " + fontFamily;
      leadDiv.innerHTML = textstring + "<br/>" + textstring;
      document.body.appendChild(leadDiv);

      // make some initial guess at the text leading (using the standard TeX ratio)
      metrics.leading = 1.2 * fontSize;

      // then we try to get the real value from the browser
      var leadDivHeight = getCSSValue(leadDiv,"height");
      leadDivHeight = leadDivHeight.replace("px","");
      if (leadDivHeight >= fontSize * 2) { metrics.leading = (leadDivHeight/2) | 0; }
      document.body.removeChild(leadDiv);

      // if we're not dealing with white space, we can compute metrics
      if (!isSpace) {
          // Have characters, so measure the text
          var canvas = document.createElement("canvas");
          var padding = 100;
          canvas.width = metrics.width + padding;
          canvas.height = 3*fontSize;
          canvas.style.opacity = 1;
          canvas.style.fontFamily = fontFamily;
          canvas.style.fontSize = fontSize;
          canvas.style.fontStyle = fontStyle;
          canvas.style.fontWeight = fontWeight;
          var ctx = canvas.getContext("2d");
          ctx.font = fontStyle + " " + fontWeight + " " + fontSize + "px " + fontFamily;

          var w = canvas.width,
              h = canvas.height,
              baseline = h/2;

          // Set all canvas pixeldata values to 255, with all the content
          // data being 0. This lets us scan for data[i] != 255.
          ctx.fillStyle = "white";
          ctx.fillRect(-1, -1, w + 2, h + 2);

          if (stroke) {
              ctx.strokeStyle = "black";
              ctx.lineWidth = context2D.lineWidth;
              ctx.strokeText(textstring, (padding / 2), baseline);
          }

          if (fill) {
              ctx.fillStyle = "black";
              ctx.fillText(textstring, padding / 2, baseline);
          }

          var pixelData = ctx.getImageData(0, 0, w, h).data;

          // canvas pixel data is w*4 by h*4, because R, G, B and A are separate,
          // consecutive values in the array, rather than stored as 32 bit ints.
          var i = 0,
              w4 = w * 4,
              len = pixelData.length;

          // Finding the ascent uses a normal, forward scanline
          while (++i < len && pixelData[i] === 255) {}
          var ascent = (i/w4)|0;

          // Finding the descent uses a reverse scanline
          i = len - 1;
          while (--i > 0 && pixelData[i] === 255) {}
          var descent = (i/w4)|0;

          // find the min-x coordinate
          for(i = 0; i<len && pixelData[i] === 255; ) {
            i += w4;
            if(i>=len) { i = (i-len) + 4; }}
          var minx = ((i%w4)/4) | 0;

          // find the max-x coordinate
          var step = 1;
          for(i = len-3; i>=0 && pixelData[i] === 255; ) {
            i -= w4;
            if(i<0) { i = (len - 3) - (step++)*4; }}
          var maxx = ((i%w4)/4) + 1 | 0;

          // set font metrics
          metrics.ascent = (baseline - ascent);
          metrics.descent = (descent - baseline);
          metrics.bounds = { minx: minx - (padding/2),
                             maxx: maxx - (padding/2),
                             miny: 0,
                             maxy: descent-ascent };
          metrics.height = 1+(descent - ascent);
      }

      // if we ARE dealing with whitespace, most values will just be zero.
      else {
          // Only whitespace, so we can't measure the text
          metrics.ascent = 0;
          metrics.descent = 0;
          metrics.bounds = { minx: 0,
                             maxx: metrics.width, // Best guess
                             miny: 0,
                             maxy: 0 };
          metrics.height = 0;
      }
      return metrics;
    };

  var imageSmoothingEnabledName;

  /**
   * Writes the given text into a new canvas.  The canvas will be sized to fit the text.
   * If text is blank, returns undefined.
   *
   * @param {String} text The text to write.
   * @param {Object} [options] Object with the following properties:
   * @param {String} [options.font='10px sans-serif'] The CSS font to use.
   * @param {String} [options.textBaseline='bottom'] The baseline of the text.
   * @param {Boolean} [options.fill=true] Whether to fill the text.
   * @param {Boolean} [options.stroke=false] Whether to stroke the text.
   * @param {Color} [options.fillColor=Color.WHITE] The fill color.
   * @param {Color} [options.strokeColor=Color.BLACK] The stroke color.
   * @param {Number} [options.strokeWidth=1] The stroke width.
   * @param {Color} [options.backgroundColor=Color.TRANSPARENT] The background color of the canvas.
   * @param {Number} [options.padding=0] The pixel size of the padding to add around the text.
   * @returns {HTMLCanvasElement} A new canvas with the given text drawn into it.  The dimensions object
   *                   from measureText will also be added to the returned canvas. If text is
   *                   blank, returns undefined.
   * @function writeTextToCanvas
   */
  function writeTextToCanvas(text, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(text)) {
      throw new DeveloperError("text is required.");
    }
    //>>includeEnd('debug');
    if (text === "") {
      return undefined;
    }

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var font = defaultValue(options.font, "10px sans-serif");
    var stroke = defaultValue(options.stroke, false);
    var fill = defaultValue(options.fill, true);
    var strokeWidth = defaultValue(options.strokeWidth, 1);
    var backgroundColor = defaultValue(
      options.backgroundColor,
      Color.TRANSPARENT
    );
    var padding = defaultValue(options.padding, 0);
    var doublePadding = padding * 2.0;

    var canvas = document.createElement("canvas");
    canvas.width = 1;
    canvas.height = 1;
    canvas.style.font = font;

    var context2D = canvas.getContext("2d");

    if (!defined(imageSmoothingEnabledName)) {
      if (defined(context2D.imageSmoothingEnabled)) {
        imageSmoothingEnabledName = "imageSmoothingEnabled";
      } else if (defined(context2D.mozImageSmoothingEnabled)) {
        imageSmoothingEnabledName = "mozImageSmoothingEnabled";
      } else if (defined(context2D.webkitImageSmoothingEnabled)) {
        imageSmoothingEnabledName = "webkitImageSmoothingEnabled";
      } else if (defined(context2D.msImageSmoothingEnabled)) {
        imageSmoothingEnabledName = "msImageSmoothingEnabled";
      }
    }

    context2D.font = font;
    context2D.lineJoin = "round";
    context2D.lineWidth = strokeWidth;
    context2D[imageSmoothingEnabledName] = false;

    // textBaseline needs to be set before the measureText call. It won't work otherwise.
    // It's magic.
    context2D.textBaseline = defaultValue(options.textBaseline, "bottom");

    // in order for measureText to calculate style, the canvas has to be
    // (temporarily) added to the DOM.
    canvas.style.visibility = "hidden";
    document.body.appendChild(canvas);

    var dimensions = measureText(context2D, text, stroke, fill);
    canvas.dimensions = dimensions;

    document.body.removeChild(canvas);
    canvas.style.visibility = "";

    //Some characters, such as the letter j, have a non-zero starting position.
    //This value is used for kerning later, but we need to take it into account
    //now in order to draw the text completely on the canvas
    var x = -dimensions.bounds.minx;

    //Expand the width to include the starting position.
    var width = Math.ceil(dimensions.width) + x + doublePadding;

    //While the height of the letter is correct, we need to adjust
    //where we start drawing it so that letters like j and y properly dip
    //below the line.

    var height = dimensions.height + doublePadding;
    var baseline = height - dimensions.ascent + padding;
    var y = height - baseline + doublePadding;

    canvas.width = width;
    canvas.height = height;

    // Properties must be explicitly set again after changing width and height
    context2D.font = font;
    context2D.lineJoin = "round";
    context2D.lineWidth = strokeWidth;
    context2D[imageSmoothingEnabledName] = false;

    // Draw background
    if (backgroundColor !== Color.TRANSPARENT) {
      context2D.fillStyle = backgroundColor.toCssColorString();
      context2D.fillRect(0, 0, canvas.width, canvas.height);
    }

    if (stroke) {
      var strokeColor = defaultValue(options.strokeColor, Color.BLACK);
      context2D.strokeStyle = strokeColor.toCssColorString();
      context2D.strokeText(text, x + padding, y);
    }

    if (fill) {
      var fillColor = defaultValue(options.fillColor, Color.WHITE);
      context2D.fillStyle = fillColor.toCssColorString();
      context2D.fillText(text, x + padding, y);
    }

    return canvas;
  }

  /**
   * A utility class for generating custom map pins as canvas elements.
   * <br /><br />
   * <div align='center'>
   * <img src='Images/PinBuilder.png' width='500'/><br />
   * Example pins generated using both the maki icon set, which ships with Cesium, and single character text.
   * </div>
   *
   * @alias PinBuilder
   * @constructor
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Map%20Pins.html|Cesium Sandcastle PinBuilder Demo}
   */
  function PinBuilder() {
    this._cache = {};
  }

  /**
   * Creates an empty pin of the specified color and size.
   *
   * @param {Color} color The color of the pin.
   * @param {Number} size The size of the pin, in pixels.
   * @returns {HTMLCanvasElement} The canvas element that represents the generated pin.
   */
  PinBuilder.prototype.fromColor = function (color, size) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(color)) {
      throw new DeveloperError("color is required");
    }
    if (!defined(size)) {
      throw new DeveloperError("size is required");
    }
    //>>includeEnd('debug');
    return createPin(undefined, undefined, color, size, this._cache);
  };

  /**
   * Creates a pin with the specified icon, color, and size.
   *
   * @param {Resource|String} url The url of the image to be stamped onto the pin.
   * @param {Color} color The color of the pin.
   * @param {Number} size The size of the pin, in pixels.
   * @returns {HTMLCanvasElement|Promise.<HTMLCanvasElement>} The canvas element or a Promise to the canvas element that represents the generated pin.
   */
  PinBuilder.prototype.fromUrl = function (url, color, size) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(url)) {
      throw new DeveloperError("url is required");
    }
    if (!defined(color)) {
      throw new DeveloperError("color is required");
    }
    if (!defined(size)) {
      throw new DeveloperError("size is required");
    }
    //>>includeEnd('debug');
    return createPin(url, undefined, color, size, this._cache);
  };

  /**
   * Creates a pin with the specified {@link https://www.mapbox.com/maki/|maki} icon identifier, color, and size.
   *
   * @param {String} id The id of the maki icon to be stamped onto the pin.
   * @param {Color} color The color of the pin.
   * @param {Number} size The size of the pin, in pixels.
   * @returns {HTMLCanvasElement|Promise.<HTMLCanvasElement>} The canvas element or a Promise to the canvas element that represents the generated pin.
   */
  PinBuilder.prototype.fromMakiIconId = function (id, color, size) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required");
    }
    if (!defined(color)) {
      throw new DeveloperError("color is required");
    }
    if (!defined(size)) {
      throw new DeveloperError("size is required");
    }
    //>>includeEnd('debug');
    return createPin(
      buildModuleUrl("Assets/Textures/maki/" + encodeURIComponent(id) + ".png"),
      undefined,
      color,
      size,
      this._cache
    );
  };

  /**
   * Creates a pin with the specified text, color, and size.  The text will be sized to be as large as possible
   * while still being contained completely within the pin.
   *
   * @param {String} text The text to be stamped onto the pin.
   * @param {Color} color The color of the pin.
   * @param {Number} size The size of the pin, in pixels.
   * @returns {HTMLCanvasElement} The canvas element that represents the generated pin.
   */
  PinBuilder.prototype.fromText = function (text, color, size) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(text)) {
      throw new DeveloperError("text is required");
    }
    if (!defined(color)) {
      throw new DeveloperError("color is required");
    }
    if (!defined(size)) {
      throw new DeveloperError("size is required");
    }
    //>>includeEnd('debug');

    return createPin(undefined, text, color, size, this._cache);
  };

  var colorScratch = new Color();

  //This function (except for the 3 commented lines) was auto-generated from an online tool,
  //http://www.professorcloud.com/svg-to-canvas/, using Assets/Textures/pin.svg as input.
  //The reason we simply can't load and draw the SVG directly to the canvas is because
  //it taints the canvas in Internet Explorer (and possibly some other browsers); making
  //it impossible to create a WebGL texture from the result.
  function drawPin(context2D, color, size) {
    context2D.save();
    context2D.scale(size / 24, size / 24); //Added to auto-generated code to scale up to desired size.
    context2D.fillStyle = color.toCssColorString(); //Modified from auto-generated code.
    context2D.strokeStyle = color.brighten(0.6, colorScratch).toCssColorString(); //Modified from auto-generated code.
    context2D.lineWidth = 0.846;
    context2D.beginPath();
    context2D.moveTo(6.72, 0.422);
    context2D.lineTo(17.28, 0.422);
    context2D.bezierCurveTo(18.553, 0.422, 19.577, 1.758, 19.577, 3.415);
    context2D.lineTo(19.577, 10.973);
    context2D.bezierCurveTo(19.577, 12.63, 18.553, 13.966, 17.282, 13.966);
    context2D.lineTo(14.386, 14.008);
    context2D.lineTo(11.826, 23.578);
    context2D.lineTo(9.614, 14.008);
    context2D.lineTo(6.719, 13.965);
    context2D.bezierCurveTo(5.446, 13.983, 4.422, 12.629, 4.422, 10.972);
    context2D.lineTo(4.422, 3.416);
    context2D.bezierCurveTo(4.423, 1.76, 5.447, 0.423, 6.718, 0.423);
    context2D.closePath();
    context2D.fill();
    context2D.stroke();
    context2D.restore();
  }

  //This function takes an image or canvas and uses it as a template
  //to "stamp" the pin with a white image outlined in black.  The color
  //values of the input image are ignored completely and only the alpha
  //values are used.
  function drawIcon(context2D, image, size) {
    //Size is the largest image that looks good inside of pin box.
    var imageSize = size / 2.5;
    var sizeX = imageSize;
    var sizeY = imageSize;

    if (image.width > image.height) {
      sizeY = imageSize * (image.height / image.width);
    } else if (image.width < image.height) {
      sizeX = imageSize * (image.width / image.height);
    }

    //x and y are the center of the pin box
    var x = Math.round((size - sizeX) / 2);
    var y = Math.round((7 / 24) * size - sizeY / 2);

    context2D.globalCompositeOperation = "destination-out";
    context2D.drawImage(image, x - 1, y, sizeX, sizeY);
    context2D.drawImage(image, x, y - 1, sizeX, sizeY);
    context2D.drawImage(image, x + 1, y, sizeX, sizeY);
    context2D.drawImage(image, x, y + 1, sizeX, sizeY);

    context2D.globalCompositeOperation = "destination-over";
    context2D.fillStyle = Color.BLACK.toCssColorString();
    context2D.fillRect(x - 1, y - 1, sizeX + 2, sizeY + 2);

    context2D.globalCompositeOperation = "destination-out";
    context2D.drawImage(image, x, y, sizeX, sizeY);

    context2D.globalCompositeOperation = "destination-over";
    context2D.fillStyle = Color.WHITE.toCssColorString();
    context2D.fillRect(x - 1, y - 2, sizeX + 2, sizeY + 2);
  }

  var stringifyScratch = new Array(4);
  function createPin(url, label, color, size, cache) {
    //Use the parameters as a unique ID for caching.
    stringifyScratch[0] = url;
    stringifyScratch[1] = label;
    stringifyScratch[2] = color;
    stringifyScratch[3] = size;
    var id = JSON.stringify(stringifyScratch);

    var item = cache[id];
    if (defined(item)) {
      return item;
    }

    var canvas = document.createElement("canvas");
    canvas.width = size;
    canvas.height = size;

    var context2D = canvas.getContext("2d");
    drawPin(context2D, color, size);

    if (defined(url)) {
      var resource = Resource.createIfNeeded(url);

      //If we have an image url, load it and then stamp the pin.
      var promise = resource.fetchImage().then(function (image) {
        drawIcon(context2D, image, size);
        cache[id] = canvas;
        return canvas;
      });
      cache[id] = promise;
      return promise;
    } else if (defined(label)) {
      //If we have a label, write it to a canvas and then stamp the pin.
      var image = writeTextToCanvas(label, {
        font: "bold " + size + "px sans-serif",
      });
      drawIcon(context2D, image, size);
    }

    cache[id] = canvas;
    return canvas;
  }

  /**
   * The data type of a pixel.
   *
   * @enum {Number}
   * @see PostProcessStage
   */
  var PixelDatatype = {
    UNSIGNED_BYTE: WebGLConstants$1.UNSIGNED_BYTE,
    UNSIGNED_SHORT: WebGLConstants$1.UNSIGNED_SHORT,
    UNSIGNED_INT: WebGLConstants$1.UNSIGNED_INT,
    FLOAT: WebGLConstants$1.FLOAT,
    HALF_FLOAT: WebGLConstants$1.HALF_FLOAT_OES,
    UNSIGNED_INT_24_8: WebGLConstants$1.UNSIGNED_INT_24_8,
    UNSIGNED_SHORT_4_4_4_4: WebGLConstants$1.UNSIGNED_SHORT_4_4_4_4,
    UNSIGNED_SHORT_5_5_5_1: WebGLConstants$1.UNSIGNED_SHORT_5_5_5_1,
    UNSIGNED_SHORT_5_6_5: WebGLConstants$1.UNSIGNED_SHORT_5_6_5,
  };

  /**
    @private
  */
  PixelDatatype.toWebGLConstant = function (pixelDatatype, context) {
    switch (pixelDatatype) {
      case PixelDatatype.UNSIGNED_BYTE:
        return WebGLConstants$1.UNSIGNED_BYTE;
      case PixelDatatype.UNSIGNED_SHORT:
        return WebGLConstants$1.UNSIGNED_SHORT;
      case PixelDatatype.UNSIGNED_INT:
        return WebGLConstants$1.UNSIGNED_INT;
      case PixelDatatype.FLOAT:
        return WebGLConstants$1.FLOAT;
      case PixelDatatype.HALF_FLOAT:
        return context.webgl2
          ? WebGLConstants$1.HALF_FLOAT
          : WebGLConstants$1.HALF_FLOAT_OES;
      case PixelDatatype.UNSIGNED_INT_24_8:
        return WebGLConstants$1.UNSIGNED_INT_24_8;
      case PixelDatatype.UNSIGNED_SHORT_4_4_4_4:
        return WebGLConstants$1.UNSIGNED_SHORT_4_4_4_4;
      case PixelDatatype.UNSIGNED_SHORT_5_5_5_1:
        return WebGLConstants$1.UNSIGNED_SHORT_5_5_5_1;
      case PixelDatatype.UNSIGNED_SHORT_5_6_5:
        return PixelDatatype.UNSIGNED_SHORT_5_6_5;
    }
  };

  /**
    @private
  */
  PixelDatatype.isPacked = function (pixelDatatype) {
    return (
      pixelDatatype === PixelDatatype.UNSIGNED_INT_24_8 ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT_4_4_4_4 ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT_5_5_5_1 ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT_5_6_5
    );
  };

  /**
    @private
  */
  PixelDatatype.sizeInBytes = function (pixelDatatype) {
    switch (pixelDatatype) {
      case PixelDatatype.UNSIGNED_BYTE:
        return 1;
      case PixelDatatype.UNSIGNED_SHORT:
      case PixelDatatype.UNSIGNED_SHORT_4_4_4_4:
      case PixelDatatype.UNSIGNED_SHORT_5_5_5_1:
      case PixelDatatype.UNSIGNED_SHORT_5_6_5:
      case PixelDatatype.HALF_FLOAT:
        return 2;
      case PixelDatatype.UNSIGNED_INT:
      case PixelDatatype.FLOAT:
      case PixelDatatype.UNSIGNED_INT_24_8:
        return 4;
    }
  };

  /**
    @private
  */
  PixelDatatype.validate = function (pixelDatatype) {
    return (
      pixelDatatype === PixelDatatype.UNSIGNED_BYTE ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT ||
      pixelDatatype === PixelDatatype.UNSIGNED_INT ||
      pixelDatatype === PixelDatatype.FLOAT ||
      pixelDatatype === PixelDatatype.HALF_FLOAT ||
      pixelDatatype === PixelDatatype.UNSIGNED_INT_24_8 ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT_4_4_4_4 ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT_5_5_5_1 ||
      pixelDatatype === PixelDatatype.UNSIGNED_SHORT_5_6_5
    );
  };

  var PixelDatatype$1 = Object.freeze(PixelDatatype);

  /**
   * The format of a pixel, i.e., the number of components it has and what they represent.
   *
   * @enum {Number}
   */
  var PixelFormat = {
    /**
     * A pixel format containing a depth value.
     *
     * @type {Number}
     * @constant
     */
    DEPTH_COMPONENT: WebGLConstants$1.DEPTH_COMPONENT,

    /**
     * A pixel format containing a depth and stencil value, most often used with {@link PixelDatatype.UNSIGNED_INT_24_8}.
     *
     * @type {Number}
     * @constant
     */
    DEPTH_STENCIL: WebGLConstants$1.DEPTH_STENCIL,

    /**
     * A pixel format containing an alpha channel.
     *
     * @type {Number}
     * @constant
     */
    ALPHA: WebGLConstants$1.ALPHA,

    /**
     * A pixel format containing red, green, and blue channels.
     *
     * @type {Number}
     * @constant
     */
    RGB: WebGLConstants$1.RGB,

    /**
     * A pixel format containing red, green, blue, and alpha channels.
     *
     * @type {Number}
     * @constant
     */
    RGBA: WebGLConstants$1.RGBA,

    /**
     * A pixel format containing a luminance (intensity) channel.
     *
     * @type {Number}
     * @constant
     */
    LUMINANCE: WebGLConstants$1.LUMINANCE,

    /**
     * A pixel format containing luminance (intensity) and alpha channels.
     *
     * @type {Number}
     * @constant
     */
    LUMINANCE_ALPHA: WebGLConstants$1.LUMINANCE_ALPHA,

    /**
     * A pixel format containing red, green, and blue channels that is DXT1 compressed.
     *
     * @type {Number}
     * @constant
     */
    RGB_DXT1: WebGLConstants$1.COMPRESSED_RGB_S3TC_DXT1_EXT,

    /**
     * A pixel format containing red, green, blue, and alpha channels that is DXT1 compressed.
     *
     * @type {Number}
     * @constant
     */
    RGBA_DXT1: WebGLConstants$1.COMPRESSED_RGBA_S3TC_DXT1_EXT,

    /**
     * A pixel format containing red, green, blue, and alpha channels that is DXT3 compressed.
     *
     * @type {Number}
     * @constant
     */
    RGBA_DXT3: WebGLConstants$1.COMPRESSED_RGBA_S3TC_DXT3_EXT,

    /**
     * A pixel format containing red, green, blue, and alpha channels that is DXT5 compressed.
     *
     * @type {Number}
     * @constant
     */
    RGBA_DXT5: WebGLConstants$1.COMPRESSED_RGBA_S3TC_DXT5_EXT,

    /**
     * A pixel format containing red, green, and blue channels that is PVR 4bpp compressed.
     *
     * @type {Number}
     * @constant
     */
    RGB_PVRTC_4BPPV1: WebGLConstants$1.COMPRESSED_RGB_PVRTC_4BPPV1_IMG,

    /**
     * A pixel format containing red, green, and blue channels that is PVR 2bpp compressed.
     *
     * @type {Number}
     * @constant
     */
    RGB_PVRTC_2BPPV1: WebGLConstants$1.COMPRESSED_RGB_PVRTC_2BPPV1_IMG,

    /**
     * A pixel format containing red, green, blue, and alpha channels that is PVR 4bpp compressed.
     *
     * @type {Number}
     * @constant
     */
    RGBA_PVRTC_4BPPV1: WebGLConstants$1.COMPRESSED_RGBA_PVRTC_4BPPV1_IMG,

    /**
     * A pixel format containing red, green, blue, and alpha channels that is PVR 2bpp compressed.
     *
     * @type {Number}
     * @constant
     */
    RGBA_PVRTC_2BPPV1: WebGLConstants$1.COMPRESSED_RGBA_PVRTC_2BPPV1_IMG,

    /**
     * A pixel format containing red, green, and blue channels that is ETC1 compressed.
     *
     * @type {Number}
     * @constant
     */
    RGB_ETC1: WebGLConstants$1.COMPRESSED_RGB_ETC1_WEBGL,
  };

  /**
   * @private
   */
  PixelFormat.componentsLength = function (pixelFormat) {
    switch (pixelFormat) {
      case PixelFormat.RGB:
        return 3;
      case PixelFormat.RGBA:
        return 4;
      case PixelFormat.LUMINANCE_ALPHA:
        return 2;
      case PixelFormat.ALPHA:
      case PixelFormat.LUMINANCE:
        return 1;
      default:
        return 1;
    }
  };

  /**
   * @private
   */
  PixelFormat.validate = function (pixelFormat) {
    return (
      pixelFormat === PixelFormat.DEPTH_COMPONENT ||
      pixelFormat === PixelFormat.DEPTH_STENCIL ||
      pixelFormat === PixelFormat.ALPHA ||
      pixelFormat === PixelFormat.RGB ||
      pixelFormat === PixelFormat.RGBA ||
      pixelFormat === PixelFormat.LUMINANCE ||
      pixelFormat === PixelFormat.LUMINANCE_ALPHA ||
      pixelFormat === PixelFormat.RGB_DXT1 ||
      pixelFormat === PixelFormat.RGBA_DXT1 ||
      pixelFormat === PixelFormat.RGBA_DXT3 ||
      pixelFormat === PixelFormat.RGBA_DXT5 ||
      pixelFormat === PixelFormat.RGB_PVRTC_4BPPV1 ||
      pixelFormat === PixelFormat.RGB_PVRTC_2BPPV1 ||
      pixelFormat === PixelFormat.RGBA_PVRTC_4BPPV1 ||
      pixelFormat === PixelFormat.RGBA_PVRTC_2BPPV1 ||
      pixelFormat === PixelFormat.RGB_ETC1
    );
  };

  /**
   * @private
   */
  PixelFormat.isColorFormat = function (pixelFormat) {
    return (
      pixelFormat === PixelFormat.ALPHA ||
      pixelFormat === PixelFormat.RGB ||
      pixelFormat === PixelFormat.RGBA ||
      pixelFormat === PixelFormat.LUMINANCE ||
      pixelFormat === PixelFormat.LUMINANCE_ALPHA
    );
  };

  /**
   * @private
   */
  PixelFormat.isDepthFormat = function (pixelFormat) {
    return (
      pixelFormat === PixelFormat.DEPTH_COMPONENT ||
      pixelFormat === PixelFormat.DEPTH_STENCIL
    );
  };

  /**
   * @private
   */
  PixelFormat.isCompressedFormat = function (pixelFormat) {
    return (
      pixelFormat === PixelFormat.RGB_DXT1 ||
      pixelFormat === PixelFormat.RGBA_DXT1 ||
      pixelFormat === PixelFormat.RGBA_DXT3 ||
      pixelFormat === PixelFormat.RGBA_DXT5 ||
      pixelFormat === PixelFormat.RGB_PVRTC_4BPPV1 ||
      pixelFormat === PixelFormat.RGB_PVRTC_2BPPV1 ||
      pixelFormat === PixelFormat.RGBA_PVRTC_4BPPV1 ||
      pixelFormat === PixelFormat.RGBA_PVRTC_2BPPV1 ||
      pixelFormat === PixelFormat.RGB_ETC1
    );
  };

  /**
   * @private
   */
  PixelFormat.isDXTFormat = function (pixelFormat) {
    return (
      pixelFormat === PixelFormat.RGB_DXT1 ||
      pixelFormat === PixelFormat.RGBA_DXT1 ||
      pixelFormat === PixelFormat.RGBA_DXT3 ||
      pixelFormat === PixelFormat.RGBA_DXT5
    );
  };

  /**
   * @private
   */
  PixelFormat.isPVRTCFormat = function (pixelFormat) {
    return (
      pixelFormat === PixelFormat.RGB_PVRTC_4BPPV1 ||
      pixelFormat === PixelFormat.RGB_PVRTC_2BPPV1 ||
      pixelFormat === PixelFormat.RGBA_PVRTC_4BPPV1 ||
      pixelFormat === PixelFormat.RGBA_PVRTC_2BPPV1
    );
  };

  /**
   * @private
   */
  PixelFormat.isETC1Format = function (pixelFormat) {
    return pixelFormat === PixelFormat.RGB_ETC1;
  };

  /**
   * @private
   */
  PixelFormat.compressedTextureSizeInBytes = function (
    pixelFormat,
    width,
    height
  ) {
    switch (pixelFormat) {
      case PixelFormat.RGB_DXT1:
      case PixelFormat.RGBA_DXT1:
      case PixelFormat.RGB_ETC1:
        return Math.floor((width + 3) / 4) * Math.floor((height + 3) / 4) * 8;

      case PixelFormat.RGBA_DXT3:
      case PixelFormat.RGBA_DXT5:
        return Math.floor((width + 3) / 4) * Math.floor((height + 3) / 4) * 16;

      case PixelFormat.RGB_PVRTC_4BPPV1:
      case PixelFormat.RGBA_PVRTC_4BPPV1:
        return Math.floor((Math.max(width, 8) * Math.max(height, 8) * 4 + 7) / 8);

      case PixelFormat.RGB_PVRTC_2BPPV1:
      case PixelFormat.RGBA_PVRTC_2BPPV1:
        return Math.floor(
          (Math.max(width, 16) * Math.max(height, 8) * 2 + 7) / 8
        );

      default:
        return 0;
    }
  };

  /**
   * @private
   */
  PixelFormat.textureSizeInBytes = function (
    pixelFormat,
    pixelDatatype,
    width,
    height
  ) {
    var componentsLength = PixelFormat.componentsLength(pixelFormat);
    if (PixelDatatype$1.isPacked(pixelDatatype)) {
      componentsLength = 1;
    }
    return (
      componentsLength * PixelDatatype$1.sizeInBytes(pixelDatatype) * width * height
    );
  };

  /**
   * @private
   */
  PixelFormat.alignmentInBytes = function (pixelFormat, pixelDatatype, width) {
    var mod =
      PixelFormat.textureSizeInBytes(pixelFormat, pixelDatatype, width, 1) % 4;
    return mod === 0 ? 4 : mod === 2 ? 2 : 1;
  };

  /**
   * @private
   */
  PixelFormat.createTypedArray = function (
    pixelFormat,
    pixelDatatype,
    width,
    height
  ) {
    var constructor;
    var sizeInBytes = PixelDatatype$1.sizeInBytes(pixelDatatype);
    if (sizeInBytes === Uint8Array.BYTES_PER_ELEMENT) {
      constructor = Uint8Array;
    } else if (sizeInBytes === Uint16Array.BYTES_PER_ELEMENT) {
      constructor = Uint16Array;
    } else if (
      sizeInBytes === Float32Array.BYTES_PER_ELEMENT &&
      pixelDatatype === PixelDatatype$1.FLOAT
    ) {
      constructor = Float32Array;
    } else {
      constructor = Uint32Array;
    }

    var size = PixelFormat.componentsLength(pixelFormat) * width * height;
    return new constructor(size);
  };

  /**
   * @private
   */
  PixelFormat.flipY = function (
    bufferView,
    pixelFormat,
    pixelDatatype,
    width,
    height
  ) {
    if (height === 1) {
      return bufferView;
    }
    var flipped = PixelFormat.createTypedArray(
      pixelFormat,
      pixelDatatype,
      width,
      height
    );
    var numberOfComponents = PixelFormat.componentsLength(pixelFormat);
    var textureWidth = width * numberOfComponents;
    for (var i = 0; i < height; ++i) {
      var row = i * width * numberOfComponents;
      var flippedRow = (height - i - 1) * width * numberOfComponents;
      for (var j = 0; j < textureWidth; ++j) {
        flipped[flippedRow + j] = bufferView[row + j];
      }
    }
    return flipped;
  };

  /**
   * @private
   */
  PixelFormat.toInternalFormat = function (pixelFormat, pixelDatatype, context) {
    // WebGL 1 require internalFormat to be the same as PixelFormat
    if (!context.webgl2) {
      return pixelFormat;
    }

    // Convert pixelFormat to correct internalFormat for WebGL 2
    if (pixelFormat === PixelFormat.DEPTH_STENCIL) {
      return WebGLConstants$1.DEPTH24_STENCIL8;
    }

    if (pixelFormat === PixelFormat.DEPTH_COMPONENT) {
      if (pixelDatatype === PixelDatatype$1.UNSIGNED_SHORT) {
        return WebGLConstants$1.DEPTH_COMPONENT16;
      } else if (pixelDatatype === PixelDatatype$1.UNSIGNED_INT) {
        return WebGLConstants$1.DEPTH_COMPONENT24;
      }
    }

    if (pixelDatatype === PixelDatatype$1.FLOAT) {
      switch (pixelFormat) {
        case PixelFormat.RGBA:
          return WebGLConstants$1.RGBA32F;
        case PixelFormat.RGB:
          return WebGLConstants$1.RGB32F;
        case PixelFormat.RG:
          return WebGLConstants$1.RG32F;
        case PixelFormat.R:
          return WebGLConstants$1.R32F;
      }
    }

    if (pixelDatatype === PixelDatatype$1.HALF_FLOAT) {
      switch (pixelFormat) {
        case PixelFormat.RGBA:
          return WebGLConstants$1.RGBA16F;
        case PixelFormat.RGB:
          return WebGLConstants$1.RGB16F;
        case PixelFormat.RG:
          return WebGLConstants$1.RG16F;
        case PixelFormat.R:
          return WebGLConstants$1.R16F;
      }
    }

    return pixelFormat;
  };

  var PixelFormat$1 = Object.freeze(PixelFormat);

  /**
   * Describes geometry representing a plane centered at the origin, with a unit width and length.
   *
   * @alias PlaneGeometry
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @example
   * var planeGeometry = new Cesium.PlaneGeometry({
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY
   * });
   */
  function PlaneGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);

    this._vertexFormat = vertexFormat;
    this._workerName = "createPlaneGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  PlaneGeometry.packedLength = VertexFormat.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PlaneGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PlaneGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    VertexFormat.pack(value._vertexFormat, array, startingIndex);

    return array;
  };

  var scratchVertexFormat$7 = new VertexFormat();
  var scratchOptions$e = {
    vertexFormat: scratchVertexFormat$7,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PlaneGeometry} [result] The object into which to store the result.
   * @returns {PlaneGeometry} The modified result parameter or a new PlaneGeometry instance if one was not provided.
   */
  PlaneGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$7
    );

    if (!defined(result)) {
      return new PlaneGeometry(scratchOptions$e);
    }

    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);

    return result;
  };

  var min = new Cartesian3(-0.5, -0.5, 0.0);
  var max = new Cartesian3(0.5, 0.5, 0.0);

  /**
   * Computes the geometric representation of a plane, including its vertices, indices, and a bounding sphere.
   *
   * @param {PlaneGeometry} planeGeometry A description of the plane.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PlaneGeometry.createGeometry = function (planeGeometry) {
    var vertexFormat = planeGeometry._vertexFormat;

    var attributes = new GeometryAttributes();
    var indices;
    var positions;

    if (vertexFormat.position) {
      // 4 corner points.  Duplicated 3 times each for each incident edge/face.
      positions = new Float64Array(4 * 3);

      // +z face
      positions[0] = min.x;
      positions[1] = min.y;
      positions[2] = 0.0;
      positions[3] = max.x;
      positions[4] = min.y;
      positions[5] = 0.0;
      positions[6] = max.x;
      positions[7] = max.y;
      positions[8] = 0.0;
      positions[9] = min.x;
      positions[10] = max.y;
      positions[11] = 0.0;

      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      });

      if (vertexFormat.normal) {
        var normals = new Float32Array(4 * 3);

        // +z face
        normals[0] = 0.0;
        normals[1] = 0.0;
        normals[2] = 1.0;
        normals[3] = 0.0;
        normals[4] = 0.0;
        normals[5] = 1.0;
        normals[6] = 0.0;
        normals[7] = 0.0;
        normals[8] = 1.0;
        normals[9] = 0.0;
        normals[10] = 0.0;
        normals[11] = 1.0;

        attributes.normal = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: normals,
        });
      }

      if (vertexFormat.st) {
        var texCoords = new Float32Array(4 * 2);

        // +z face
        texCoords[0] = 0.0;
        texCoords[1] = 0.0;
        texCoords[2] = 1.0;
        texCoords[3] = 0.0;
        texCoords[4] = 1.0;
        texCoords[5] = 1.0;
        texCoords[6] = 0.0;
        texCoords[7] = 1.0;

        attributes.st = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 2,
          values: texCoords,
        });
      }

      if (vertexFormat.tangent) {
        var tangents = new Float32Array(4 * 3);

        // +z face
        tangents[0] = 1.0;
        tangents[1] = 0.0;
        tangents[2] = 0.0;
        tangents[3] = 1.0;
        tangents[4] = 0.0;
        tangents[5] = 0.0;
        tangents[6] = 1.0;
        tangents[7] = 0.0;
        tangents[8] = 0.0;
        tangents[9] = 1.0;
        tangents[10] = 0.0;
        tangents[11] = 0.0;

        attributes.tangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: tangents,
        });
      }

      if (vertexFormat.bitangent) {
        var bitangents = new Float32Array(4 * 3);

        // +z face
        bitangents[0] = 0.0;
        bitangents[1] = 1.0;
        bitangents[2] = 0.0;
        bitangents[3] = 0.0;
        bitangents[4] = 1.0;
        bitangents[5] = 0.0;
        bitangents[6] = 0.0;
        bitangents[7] = 1.0;
        bitangents[8] = 0.0;
        bitangents[9] = 0.0;
        bitangents[10] = 1.0;
        bitangents[11] = 0.0;

        attributes.bitangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: bitangents,
        });
      }

      // 2 triangles
      indices = new Uint16Array(2 * 3);

      // +z face
      indices[0] = 0;
      indices[1] = 1;
      indices[2] = 2;
      indices[3] = 0;
      indices[4] = 2;
      indices[5] = 3;
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: new BoundingSphere(Cartesian3.ZERO, Math.sqrt(2.0)),
    });
  };

  /**
   * Describes geometry representing the outline of a plane centered at the origin, with a unit width and length.
   *
   * @alias PlaneOutlineGeometry
   * @constructor
   *
   */
  function PlaneOutlineGeometry() {
    this._workerName = "createPlaneOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  PlaneOutlineGeometry.packedLength = 0;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PlaneOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   *
   * @returns {Number[]} The array that was packed into
   */
  PlaneOutlineGeometry.pack = function (value, array) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PlaneOutlineGeometry} [result] The object into which to store the result.
   * @returns {PlaneOutlineGeometry} The modified result parameter or a new PlaneOutlineGeometry instance if one was not provided.
   */
  PlaneOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new PlaneOutlineGeometry();
    }

    return result;
  };

  var min$1 = new Cartesian3(-0.5, -0.5, 0.0);
  var max$1 = new Cartesian3(0.5, 0.5, 0.0);

  /**
   * Computes the geometric representation of an outline of a plane, including its vertices, indices, and a bounding sphere.
   *
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PlaneOutlineGeometry.createGeometry = function () {
    var attributes = new GeometryAttributes();
    var indices = new Uint16Array(4 * 2);
    var positions = new Float64Array(4 * 3);

    positions[0] = min$1.x;
    positions[1] = min$1.y;
    positions[2] = min$1.z;
    positions[3] = max$1.x;
    positions[4] = min$1.y;
    positions[5] = min$1.z;
    positions[6] = max$1.x;
    positions[7] = max$1.y;
    positions[8] = min$1.z;
    positions[9] = min$1.x;
    positions[10] = max$1.y;
    positions[11] = min$1.z;

    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: positions,
    });

    indices[0] = 0;
    indices[1] = 1;
    indices[2] = 1;
    indices[3] = 2;
    indices[4] = 2;
    indices[5] = 3;
    indices[6] = 3;
    indices[7] = 0;

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: new BoundingSphere(Cartesian3.ZERO, Math.sqrt(2.0)),
    });
  };

  var scratchCarto1 = new Cartographic();
  var scratchCarto2 = new Cartographic();
  function adjustPosHeightsForNormal(position, p1, p2, ellipsoid) {
    var carto1 = ellipsoid.cartesianToCartographic(position, scratchCarto1);
    var height = carto1.height;
    var p1Carto = ellipsoid.cartesianToCartographic(p1, scratchCarto2);
    p1Carto.height = height;
    ellipsoid.cartographicToCartesian(p1Carto, p1);

    var p2Carto = ellipsoid.cartesianToCartographic(p2, scratchCarto2);
    p2Carto.height = height - 100;
    ellipsoid.cartographicToCartesian(p2Carto, p2);
  }

  var scratchBoundingRectangle = new BoundingRectangle();
  var scratchPosition$3 = new Cartesian3();
  var scratchNormal$5 = new Cartesian3();
  var scratchTangent$3 = new Cartesian3();
  var scratchBitangent$3 = new Cartesian3();
  var p1Scratch$2 = new Cartesian3();
  var p2Scratch$2 = new Cartesian3();
  var scratchPerPosNormal = new Cartesian3();
  var scratchPerPosTangent = new Cartesian3();
  var scratchPerPosBitangent = new Cartesian3();

  var appendTextureCoordinatesOrigin = new Cartesian2();
  var appendTextureCoordinatesCartesian2 = new Cartesian2();
  var appendTextureCoordinatesCartesian3 = new Cartesian3();
  var appendTextureCoordinatesQuaternion = new Quaternion();
  var appendTextureCoordinatesMatrix3 = new Matrix3();
  var tangentMatrixScratch$1 = new Matrix3();

  function computeAttributes(options) {
    var vertexFormat = options.vertexFormat;
    var geometry = options.geometry;
    var shadowVolume = options.shadowVolume;
    var flatPositions = geometry.attributes.position.values;
    var length = flatPositions.length;
    var wall = options.wall;
    var top = options.top || wall;
    var bottom = options.bottom || wall;
    if (
      vertexFormat.st ||
      vertexFormat.normal ||
      vertexFormat.tangent ||
      vertexFormat.bitangent ||
      shadowVolume
    ) {
      // PERFORMANCE_IDEA: Compute before subdivision, then just interpolate during subdivision.
      // PERFORMANCE_IDEA: Compute with createGeometryFromPositions() for fast path when there's no holes.
      var boundingRectangle = options.boundingRectangle;
      var tangentPlane = options.tangentPlane;
      var ellipsoid = options.ellipsoid;
      var stRotation = options.stRotation;
      var perPositionHeight = options.perPositionHeight;

      var origin = appendTextureCoordinatesOrigin;
      origin.x = boundingRectangle.x;
      origin.y = boundingRectangle.y;

      var textureCoordinates = vertexFormat.st
        ? new Float32Array(2 * (length / 3))
        : undefined;
      var normals;
      if (vertexFormat.normal) {
        if (perPositionHeight && top && !wall) {
          normals = geometry.attributes.normal.values;
        } else {
          normals = new Float32Array(length);
        }
      }
      var tangents = vertexFormat.tangent ? new Float32Array(length) : undefined;
      var bitangents = vertexFormat.bitangent
        ? new Float32Array(length)
        : undefined;
      var extrudeNormals = shadowVolume ? new Float32Array(length) : undefined;

      var textureCoordIndex = 0;
      var attrIndex = 0;

      var normal = scratchNormal$5;
      var tangent = scratchTangent$3;
      var bitangent = scratchBitangent$3;
      var recomputeNormal = true;

      var textureMatrix = appendTextureCoordinatesMatrix3;
      var tangentRotationMatrix = tangentMatrixScratch$1;
      if (stRotation !== 0.0) {
        var rotation = Quaternion.fromAxisAngle(
          tangentPlane._plane.normal,
          stRotation,
          appendTextureCoordinatesQuaternion
        );
        textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrix);

        rotation = Quaternion.fromAxisAngle(
          tangentPlane._plane.normal,
          -stRotation,
          appendTextureCoordinatesQuaternion
        );
        tangentRotationMatrix = Matrix3.fromQuaternion(
          rotation,
          tangentRotationMatrix
        );
      } else {
        textureMatrix = Matrix3.clone(Matrix3.IDENTITY, textureMatrix);
        tangentRotationMatrix = Matrix3.clone(
          Matrix3.IDENTITY,
          tangentRotationMatrix
        );
      }

      var bottomOffset = 0;
      var bottomOffset2 = 0;

      if (top && bottom) {
        bottomOffset = length / 2;
        bottomOffset2 = length / 3;

        length /= 2;
      }

      for (var i = 0; i < length; i += 3) {
        var position = Cartesian3.fromArray(
          flatPositions,
          i,
          appendTextureCoordinatesCartesian3
        );

        if (vertexFormat.st) {
          var p = Matrix3.multiplyByVector(
            textureMatrix,
            position,
            scratchPosition$3
          );
          p = ellipsoid.scaleToGeodeticSurface(p, p);
          var st = tangentPlane.projectPointOntoPlane(
            p,
            appendTextureCoordinatesCartesian2
          );
          Cartesian2.subtract(st, origin, st);

          var stx = CesiumMath.clamp(st.x / boundingRectangle.width, 0, 1);
          var sty = CesiumMath.clamp(st.y / boundingRectangle.height, 0, 1);
          if (bottom) {
            textureCoordinates[textureCoordIndex + bottomOffset2] = stx;
            textureCoordinates[textureCoordIndex + 1 + bottomOffset2] = sty;
          }
          if (top) {
            textureCoordinates[textureCoordIndex] = stx;
            textureCoordinates[textureCoordIndex + 1] = sty;
          }

          textureCoordIndex += 2;
        }

        if (
          vertexFormat.normal ||
          vertexFormat.tangent ||
          vertexFormat.bitangent ||
          shadowVolume
        ) {
          var attrIndex1 = attrIndex + 1;
          var attrIndex2 = attrIndex + 2;

          if (wall) {
            if (i + 3 < length) {
              var p1 = Cartesian3.fromArray(flatPositions, i + 3, p1Scratch$2);

              if (recomputeNormal) {
                var p2 = Cartesian3.fromArray(
                  flatPositions,
                  i + length,
                  p2Scratch$2
                );
                if (perPositionHeight) {
                  adjustPosHeightsForNormal(position, p1, p2, ellipsoid);
                }
                Cartesian3.subtract(p1, position, p1);
                Cartesian3.subtract(p2, position, p2);
                normal = Cartesian3.normalize(
                  Cartesian3.cross(p2, p1, normal),
                  normal
                );
                recomputeNormal = false;
              }

              if (Cartesian3.equalsEpsilon(p1, position, CesiumMath.EPSILON10)) {
                // if we've reached a corner
                recomputeNormal = true;
              }
            }

            if (vertexFormat.tangent || vertexFormat.bitangent) {
              bitangent = ellipsoid.geodeticSurfaceNormal(position, bitangent);
              if (vertexFormat.tangent) {
                tangent = Cartesian3.normalize(
                  Cartesian3.cross(bitangent, normal, tangent),
                  tangent
                );
              }
            }
          } else {
            normal = ellipsoid.geodeticSurfaceNormal(position, normal);
            if (vertexFormat.tangent || vertexFormat.bitangent) {
              if (perPositionHeight) {
                scratchPerPosNormal = Cartesian3.fromArray(
                  normals,
                  attrIndex,
                  scratchPerPosNormal
                );
                scratchPerPosTangent = Cartesian3.cross(
                  Cartesian3.UNIT_Z,
                  scratchPerPosNormal,
                  scratchPerPosTangent
                );
                scratchPerPosTangent = Cartesian3.normalize(
                  Matrix3.multiplyByVector(
                    tangentRotationMatrix,
                    scratchPerPosTangent,
                    scratchPerPosTangent
                  ),
                  scratchPerPosTangent
                );
                if (vertexFormat.bitangent) {
                  scratchPerPosBitangent = Cartesian3.normalize(
                    Cartesian3.cross(
                      scratchPerPosNormal,
                      scratchPerPosTangent,
                      scratchPerPosBitangent
                    ),
                    scratchPerPosBitangent
                  );
                }
              }

              tangent = Cartesian3.cross(Cartesian3.UNIT_Z, normal, tangent);
              tangent = Cartesian3.normalize(
                Matrix3.multiplyByVector(tangentRotationMatrix, tangent, tangent),
                tangent
              );
              if (vertexFormat.bitangent) {
                bitangent = Cartesian3.normalize(
                  Cartesian3.cross(normal, tangent, bitangent),
                  bitangent
                );
              }
            }
          }

          if (vertexFormat.normal) {
            if (options.wall) {
              normals[attrIndex + bottomOffset] = normal.x;
              normals[attrIndex1 + bottomOffset] = normal.y;
              normals[attrIndex2 + bottomOffset] = normal.z;
            } else if (bottom) {
              normals[attrIndex + bottomOffset] = -normal.x;
              normals[attrIndex1 + bottomOffset] = -normal.y;
              normals[attrIndex2 + bottomOffset] = -normal.z;
            }

            if ((top && !perPositionHeight) || wall) {
              normals[attrIndex] = normal.x;
              normals[attrIndex1] = normal.y;
              normals[attrIndex2] = normal.z;
            }
          }

          if (shadowVolume) {
            if (wall) {
              normal = ellipsoid.geodeticSurfaceNormal(position, normal);
            }
            extrudeNormals[attrIndex + bottomOffset] = -normal.x;
            extrudeNormals[attrIndex1 + bottomOffset] = -normal.y;
            extrudeNormals[attrIndex2 + bottomOffset] = -normal.z;
          }

          if (vertexFormat.tangent) {
            if (options.wall) {
              tangents[attrIndex + bottomOffset] = tangent.x;
              tangents[attrIndex1 + bottomOffset] = tangent.y;
              tangents[attrIndex2 + bottomOffset] = tangent.z;
            } else if (bottom) {
              tangents[attrIndex + bottomOffset] = -tangent.x;
              tangents[attrIndex1 + bottomOffset] = -tangent.y;
              tangents[attrIndex2 + bottomOffset] = -tangent.z;
            }

            if (top) {
              if (perPositionHeight) {
                tangents[attrIndex] = scratchPerPosTangent.x;
                tangents[attrIndex1] = scratchPerPosTangent.y;
                tangents[attrIndex2] = scratchPerPosTangent.z;
              } else {
                tangents[attrIndex] = tangent.x;
                tangents[attrIndex1] = tangent.y;
                tangents[attrIndex2] = tangent.z;
              }
            }
          }

          if (vertexFormat.bitangent) {
            if (bottom) {
              bitangents[attrIndex + bottomOffset] = bitangent.x;
              bitangents[attrIndex1 + bottomOffset] = bitangent.y;
              bitangents[attrIndex2 + bottomOffset] = bitangent.z;
            }
            if (top) {
              if (perPositionHeight) {
                bitangents[attrIndex] = scratchPerPosBitangent.x;
                bitangents[attrIndex1] = scratchPerPosBitangent.y;
                bitangents[attrIndex2] = scratchPerPosBitangent.z;
              } else {
                bitangents[attrIndex] = bitangent.x;
                bitangents[attrIndex1] = bitangent.y;
                bitangents[attrIndex2] = bitangent.z;
              }
            }
          }
          attrIndex += 3;
        }
      }

      if (vertexFormat.st) {
        geometry.attributes.st = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 2,
          values: textureCoordinates,
        });
      }

      if (vertexFormat.normal) {
        geometry.attributes.normal = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: normals,
        });
      }

      if (vertexFormat.tangent) {
        geometry.attributes.tangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: tangents,
        });
      }

      if (vertexFormat.bitangent) {
        geometry.attributes.bitangent = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: bitangents,
        });
      }

      if (shadowVolume) {
        geometry.attributes.extrudeDirection = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
          values: extrudeNormals,
        });
      }
    }

    if (options.extrude && defined(options.offsetAttribute)) {
      var size = flatPositions.length / 3;
      var offsetAttribute = new Uint8Array(size);

      if (options.offsetAttribute === GeometryOffsetAttribute$1.TOP) {
        if ((top && bottom) || wall) {
          offsetAttribute = arrayFill(offsetAttribute, 1, 0, size / 2);
        } else if (top) {
          offsetAttribute = arrayFill(offsetAttribute, 1);
        }
      } else {
        var offsetValue =
          options.offsetAttribute === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        offsetAttribute = arrayFill(offsetAttribute, offsetValue);
      }

      geometry.attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: offsetAttribute,
      });
    }

    return geometry;
  }

  var startCartographicScratch$1 = new Cartographic();
  var endCartographicScratch$1 = new Cartographic();
  var idlCross = {
    westOverIDL: 0.0,
    eastOverIDL: 0.0,
  };
  var ellipsoidGeodesic$1 = new EllipsoidGeodesic();
  function computeRectangle$2(positions, ellipsoid, arcType, granularity, result) {
    result = defaultValue(result, new Rectangle());
    if (!defined(positions) || positions.length < 3) {
      result.west = 0.0;
      result.north = 0.0;
      result.south = 0.0;
      result.east = 0.0;
      return result;
    }

    if (arcType === ArcType$1.RHUMB) {
      return Rectangle.fromCartesianArray(positions, ellipsoid, result);
    }

    if (!ellipsoidGeodesic$1.ellipsoid.equals(ellipsoid)) {
      ellipsoidGeodesic$1 = new EllipsoidGeodesic(undefined, undefined, ellipsoid);
    }

    result.west = Number.POSITIVE_INFINITY;
    result.east = Number.NEGATIVE_INFINITY;
    result.south = Number.POSITIVE_INFINITY;
    result.north = Number.NEGATIVE_INFINITY;

    idlCross.westOverIDL = Number.POSITIVE_INFINITY;
    idlCross.eastOverIDL = Number.NEGATIVE_INFINITY;

    var inverseChordLength =
      1.0 / CesiumMath.chordLength(granularity, ellipsoid.maximumRadius);
    var positionsLength = positions.length;
    var endCartographic = ellipsoid.cartesianToCartographic(
      positions[0],
      endCartographicScratch$1
    );
    var startCartographic = startCartographicScratch$1;
    var swap;

    for (var i = 1; i < positionsLength; i++) {
      swap = startCartographic;
      startCartographic = endCartographic;
      endCartographic = ellipsoid.cartesianToCartographic(positions[i], swap);
      ellipsoidGeodesic$1.setEndPoints(startCartographic, endCartographic);
      interpolateAndGrowRectangle(
        ellipsoidGeodesic$1,
        inverseChordLength,
        result,
        idlCross
      );
    }

    swap = startCartographic;
    startCartographic = endCartographic;
    endCartographic = ellipsoid.cartesianToCartographic(positions[0], swap);
    ellipsoidGeodesic$1.setEndPoints(startCartographic, endCartographic);
    interpolateAndGrowRectangle(
      ellipsoidGeodesic$1,
      inverseChordLength,
      result,
      idlCross
    );

    if (result.east - result.west > idlCross.eastOverIDL - idlCross.westOverIDL) {
      result.west = idlCross.westOverIDL;
      result.east = idlCross.eastOverIDL;

      if (result.east > CesiumMath.PI) {
        result.east = result.east - CesiumMath.TWO_PI;
      }
      if (result.west > CesiumMath.PI) {
        result.west = result.west - CesiumMath.TWO_PI;
      }
    }

    return result;
  }

  var interpolatedCartographicScratch$1 = new Cartographic();
  function interpolateAndGrowRectangle(
    ellipsoidGeodesic,
    inverseChordLength,
    result,
    idlCross
  ) {
    var segmentLength = ellipsoidGeodesic.surfaceDistance;

    var numPoints = Math.ceil(segmentLength * inverseChordLength);
    var subsegmentDistance =
      numPoints > 0 ? segmentLength / (numPoints - 1) : Number.POSITIVE_INFINITY;
    var interpolationDistance = 0.0;

    for (var i = 0; i < numPoints; i++) {
      var interpolatedCartographic = ellipsoidGeodesic.interpolateUsingSurfaceDistance(
        interpolationDistance,
        interpolatedCartographicScratch$1
      );
      interpolationDistance += subsegmentDistance;
      var longitude = interpolatedCartographic.longitude;
      var latitude = interpolatedCartographic.latitude;

      result.west = Math.min(result.west, longitude);
      result.east = Math.max(result.east, longitude);
      result.south = Math.min(result.south, latitude);
      result.north = Math.max(result.north, latitude);

      var lonAdjusted =
        longitude >= 0 ? longitude : longitude + CesiumMath.TWO_PI;
      idlCross.westOverIDL = Math.min(idlCross.westOverIDL, lonAdjusted);
      idlCross.eastOverIDL = Math.max(idlCross.eastOverIDL, lonAdjusted);
    }
  }

  var createGeometryFromPositionsExtrudedPositions = [];

  function createGeometryFromPositionsExtruded(
    ellipsoid,
    polygon,
    granularity,
    hierarchy,
    perPositionHeight,
    closeTop,
    closeBottom,
    vertexFormat,
    arcType
  ) {
    var geos = {
      walls: [],
    };
    var i;

    if (closeTop || closeBottom) {
      var topGeo = PolygonGeometryLibrary.createGeometryFromPositions(
        ellipsoid,
        polygon,
        granularity,
        perPositionHeight,
        vertexFormat,
        arcType
      );

      var edgePoints = topGeo.attributes.position.values;
      var indices = topGeo.indices;
      var numPositions;
      var newIndices;

      if (closeTop && closeBottom) {
        var topBottomPositions = edgePoints.concat(edgePoints);

        numPositions = topBottomPositions.length / 3;

        newIndices = IndexDatatype$1.createTypedArray(
          numPositions,
          indices.length * 2
        );
        newIndices.set(indices);
        var ilength = indices.length;

        var length = numPositions / 2;

        for (i = 0; i < ilength; i += 3) {
          var i0 = newIndices[i] + length;
          var i1 = newIndices[i + 1] + length;
          var i2 = newIndices[i + 2] + length;

          newIndices[i + ilength] = i2;
          newIndices[i + 1 + ilength] = i1;
          newIndices[i + 2 + ilength] = i0;
        }

        topGeo.attributes.position.values = topBottomPositions;
        if (perPositionHeight && vertexFormat.normal) {
          var normals = topGeo.attributes.normal.values;
          topGeo.attributes.normal.values = new Float32Array(
            topBottomPositions.length
          );
          topGeo.attributes.normal.values.set(normals);
        }
        topGeo.indices = newIndices;
      } else if (closeBottom) {
        numPositions = edgePoints.length / 3;
        newIndices = IndexDatatype$1.createTypedArray(numPositions, indices.length);

        for (i = 0; i < indices.length; i += 3) {
          newIndices[i] = indices[i + 2];
          newIndices[i + 1] = indices[i + 1];
          newIndices[i + 2] = indices[i];
        }

        topGeo.indices = newIndices;
      }

      geos.topAndBottom = new GeometryInstance({
        geometry: topGeo,
      });
    }

    var outerRing = hierarchy.outerRing;
    var tangentPlane = EllipsoidTangentPlane.fromPoints(outerRing, ellipsoid);
    var positions2D = tangentPlane.projectPointsOntoPlane(
      outerRing,
      createGeometryFromPositionsExtrudedPositions
    );

    var windingOrder = PolygonPipeline.computeWindingOrder2D(positions2D);
    if (windingOrder === WindingOrder$1.CLOCKWISE) {
      outerRing = outerRing.slice().reverse();
    }

    var wallGeo = PolygonGeometryLibrary.computeWallGeometry(
      outerRing,
      ellipsoid,
      granularity,
      perPositionHeight,
      arcType
    );
    geos.walls.push(
      new GeometryInstance({
        geometry: wallGeo,
      })
    );

    var holes = hierarchy.holes;
    for (i = 0; i < holes.length; i++) {
      var hole = holes[i];

      tangentPlane = EllipsoidTangentPlane.fromPoints(hole, ellipsoid);
      positions2D = tangentPlane.projectPointsOntoPlane(
        hole,
        createGeometryFromPositionsExtrudedPositions
      );

      windingOrder = PolygonPipeline.computeWindingOrder2D(positions2D);
      if (windingOrder === WindingOrder$1.COUNTER_CLOCKWISE) {
        hole = hole.slice().reverse();
      }

      wallGeo = PolygonGeometryLibrary.computeWallGeometry(
        hole,
        ellipsoid,
        granularity,
        perPositionHeight,
        arcType
      );
      geos.walls.push(
        new GeometryInstance({
          geometry: wallGeo,
        })
      );
    }

    return geos;
  }

  /**
   * A description of a polygon on the ellipsoid. The polygon is defined by a polygon hierarchy. Polygon geometry can be rendered with both {@link Primitive} and {@link GroundPrimitive}.
   *
   * @alias PolygonGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {PolygonHierarchy} options.polygonHierarchy A polygon hierarchy that can include holes.
   * @param {Number} [options.height=0.0] The distance in meters between the polygon and the ellipsoid surface.
   * @param {Number} [options.extrudedHeight] The distance in meters between the polygon's extruded face and the ellipsoid surface.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates, in radians. A positive rotation is counter-clockwise.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Boolean} [options.perPositionHeight=false] Use the height of options.positions for each position instead of using options.height to determine the height.
   * @param {Boolean} [options.closeTop=true] When false, leaves off the top of an extruded polygon open.
   * @param {Boolean} [options.closeBottom=true] When false, leaves off the bottom of an extruded polygon open.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of line the polygon edges must follow. Valid options are {@link ArcType.GEODESIC} and {@link ArcType.RHUMB}.
   *
   * @see PolygonGeometry#createGeometry
   * @see PolygonGeometry#fromPositions
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Polygon.html|Cesium Sandcastle Polygon Demo}
   *
   * @example
   * // 1. create a polygon from points
   * var polygon = new Cesium.PolygonGeometry({
   *   polygonHierarchy : new Cesium.PolygonHierarchy(
   *     Cesium.Cartesian3.fromDegreesArray([
   *       -72.0, 40.0,
   *       -70.0, 35.0,
   *       -75.0, 30.0,
   *       -70.0, 30.0,
   *       -68.0, 40.0
   *     ])
   *   )
   * });
   * var geometry = Cesium.PolygonGeometry.createGeometry(polygon);
   *
   * // 2. create a nested polygon with holes
   * var polygonWithHole = new Cesium.PolygonGeometry({
   *   polygonHierarchy : new Cesium.PolygonHierarchy(
   *     Cesium.Cartesian3.fromDegreesArray([
   *       -109.0, 30.0,
   *       -95.0, 30.0,
   *       -95.0, 40.0,
   *       -109.0, 40.0
   *     ]),
   *     [new Cesium.PolygonHierarchy(
   *       Cesium.Cartesian3.fromDegreesArray([
   *         -107.0, 31.0,
   *         -107.0, 39.0,
   *         -97.0, 39.0,
   *         -97.0, 31.0
   *       ]),
   *       [new Cesium.PolygonHierarchy(
   *         Cesium.Cartesian3.fromDegreesArray([
   *           -105.0, 33.0,
   *           -99.0, 33.0,
   *           -99.0, 37.0,
   *           -105.0, 37.0
   *         ]),
   *         [new Cesium.PolygonHierarchy(
   *           Cesium.Cartesian3.fromDegreesArray([
   *             -103.0, 34.0,
   *             -101.0, 34.0,
   *             -101.0, 36.0,
   *             -103.0, 36.0
   *           ])
   *         )]
   *       )]
   *     )]
   *   )
   * });
   * var geometry = Cesium.PolygonGeometry.createGeometry(polygonWithHole);
   *
   * // 3. create extruded polygon
   * var extrudedPolygon = new Cesium.PolygonGeometry({
   *   polygonHierarchy : new Cesium.PolygonHierarchy(
   *     Cesium.Cartesian3.fromDegreesArray([
   *       -72.0, 40.0,
   *       -70.0, 35.0,
   *       -75.0, 30.0,
   *       -70.0, 30.0,
   *       -68.0, 40.0
   *     ])
   *   ),
   *   extrudedHeight: 300000
   * });
   * var geometry = Cesium.PolygonGeometry.createGeometry(extrudedPolygon);
   */
  function PolygonGeometry(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.polygonHierarchy", options.polygonHierarchy);
    if (
      defined(options.perPositionHeight) &&
      options.perPositionHeight &&
      defined(options.height)
    ) {
      throw new DeveloperError(
        "Cannot use both options.perPositionHeight and options.height"
      );
    }
    if (
      defined(options.arcType) &&
      options.arcType !== ArcType$1.GEODESIC &&
      options.arcType !== ArcType$1.RHUMB
    ) {
      throw new DeveloperError(
        "Invalid arcType. Valid options are ArcType.GEODESIC and ArcType.RHUMB."
      );
    }
    //>>includeEnd('debug');

    var polygonHierarchy = options.polygonHierarchy;
    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var stRotation = defaultValue(options.stRotation, 0.0);
    var perPositionHeight = defaultValue(options.perPositionHeight, false);
    var perPositionHeightExtrude =
      perPositionHeight && defined(options.extrudedHeight);
    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    if (!perPositionHeightExtrude) {
      var h = Math.max(height, extrudedHeight);
      extrudedHeight = Math.min(height, extrudedHeight);
      height = h;
    }

    this._vertexFormat = VertexFormat.clone(vertexFormat);
    this._ellipsoid = Ellipsoid.clone(ellipsoid);
    this._granularity = granularity;
    this._stRotation = stRotation;
    this._height = height;
    this._extrudedHeight = extrudedHeight;
    this._closeTop = defaultValue(options.closeTop, true);
    this._closeBottom = defaultValue(options.closeBottom, true);
    this._polygonHierarchy = polygonHierarchy;
    this._perPositionHeight = perPositionHeight;
    this._perPositionHeightExtrude = perPositionHeightExtrude;
    this._shadowVolume = defaultValue(options.shadowVolume, false);
    this._workerName = "createPolygonGeometry";
    this._offsetAttribute = options.offsetAttribute;
    this._arcType = defaultValue(options.arcType, ArcType$1.GEODESIC);

    this._rectangle = undefined;
    this._textureCoordinateRotationPoints = undefined;

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      PolygonGeometryLibrary.computeHierarchyPackedLength(polygonHierarchy) +
      Ellipsoid.packedLength +
      VertexFormat.packedLength +
      12;
  }

  /**
   * A description of a polygon from an array of positions. Polygon geometry can be rendered with both {@link Primitive} and {@link GroundPrimitive}.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that defined the corner points of the polygon.
   * @param {Number} [options.height=0.0] The height of the polygon.
   * @param {Number} [options.extrudedHeight] The height of the polygon extrusion.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates, in radians. A positive rotation is counter-clockwise.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Boolean} [options.perPositionHeight=false] Use the height of options.positions for each position instead of using options.height to determine the height.
   * @param {Boolean} [options.closeTop=true] When false, leaves off the top of an extruded polygon open.
   * @param {Boolean} [options.closeBottom=true] When false, leaves off the bottom of an extruded polygon open.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of line the polygon edges must follow. Valid options are {@link ArcType.GEODESIC} and {@link ArcType.RHUMB}.
   * @returns {PolygonGeometry}
   *
   *
   * @example
   * // create a polygon from points
   * var polygon = Cesium.PolygonGeometry.fromPositions({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     -72.0, 40.0,
   *     -70.0, 35.0,
   *     -75.0, 30.0,
   *     -70.0, 30.0,
   *     -68.0, 40.0
   *   ])
   * });
   * var geometry = Cesium.PolygonGeometry.createGeometry(polygon);
   *
   * @see PolygonGeometry#createGeometry
   */
  PolygonGeometry.fromPositions = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.positions", options.positions);
    //>>includeEnd('debug');

    var newOptions = {
      polygonHierarchy: {
        positions: options.positions,
      },
      height: options.height,
      extrudedHeight: options.extrudedHeight,
      vertexFormat: options.vertexFormat,
      stRotation: options.stRotation,
      ellipsoid: options.ellipsoid,
      granularity: options.granularity,
      perPositionHeight: options.perPositionHeight,
      closeTop: options.closeTop,
      closeBottom: options.closeBottom,
      offsetAttribute: options.offsetAttribute,
      arcType: options.arcType,
    };
    return new PolygonGeometry(newOptions);
  };

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PolygonGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PolygonGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    startingIndex = PolygonGeometryLibrary.packPolygonHierarchy(
      value._polygonHierarchy,
      array,
      startingIndex
    );

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._height;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._stRotation;
    array[startingIndex++] = value._perPositionHeightExtrude ? 1.0 : 0.0;
    array[startingIndex++] = value._perPositionHeight ? 1.0 : 0.0;
    array[startingIndex++] = value._closeTop ? 1.0 : 0.0;
    array[startingIndex++] = value._closeBottom ? 1.0 : 0.0;
    array[startingIndex++] = value._shadowVolume ? 1.0 : 0.0;
    array[startingIndex++] = defaultValue(value._offsetAttribute, -1);
    array[startingIndex++] = value._arcType;
    array[startingIndex] = value.packedLength;

    return array;
  };

  var scratchEllipsoid$5 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchVertexFormat$8 = new VertexFormat();

  //Only used to avoid inability to default construct.
  var dummyOptions = {
    polygonHierarchy: {},
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PolygonGeometry} [result] The object into which to store the result.
   */
  PolygonGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var polygonHierarchy = PolygonGeometryLibrary.unpackPolygonHierarchy(
      array,
      startingIndex
    );
    startingIndex = polygonHierarchy.startingIndex;
    delete polygonHierarchy.startingIndex;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$5);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$8
    );
    startingIndex += VertexFormat.packedLength;

    var height = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var granularity = array[startingIndex++];
    var stRotation = array[startingIndex++];
    var perPositionHeightExtrude = array[startingIndex++] === 1.0;
    var perPositionHeight = array[startingIndex++] === 1.0;
    var closeTop = array[startingIndex++] === 1.0;
    var closeBottom = array[startingIndex++] === 1.0;
    var shadowVolume = array[startingIndex++] === 1.0;
    var offsetAttribute = array[startingIndex++];
    var arcType = array[startingIndex++];
    var packedLength = array[startingIndex];

    if (!defined(result)) {
      result = new PolygonGeometry(dummyOptions);
    }

    result._polygonHierarchy = polygonHierarchy;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._height = height;
    result._extrudedHeight = extrudedHeight;
    result._granularity = granularity;
    result._stRotation = stRotation;
    result._perPositionHeightExtrude = perPositionHeightExtrude;
    result._perPositionHeight = perPositionHeight;
    result._closeTop = closeTop;
    result._closeBottom = closeBottom;
    result._shadowVolume = shadowVolume;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;
    result._arcType = arcType;
    result.packedLength = packedLength;
    return result;
  };

  /**
   * Returns the bounding rectangle given the provided options
   *
   * @param {Object} options Object with the following properties:
   * @param {PolygonHierarchy} options.polygonHierarchy A polygon hierarchy that can include holes.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions sampled.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of line the polygon edges must follow. Valid options are {@link ArcType.GEODESIC} and {@link ArcType.RHUMB}.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Rectangle} [result] An object in which to store the result.
   *
   * @returns {Rectangle} The result rectangle
   */
  PolygonGeometry.computeRectangle = function (options, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.polygonHierarchy", options.polygonHierarchy);
    //>>includeEnd('debug');

    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var arcType = defaultValue(options.arcType, ArcType$1.GEODESIC);
    //>>includeStart('debug', pragmas.debug);
    if (arcType !== ArcType$1.GEODESIC && arcType !== ArcType$1.RHUMB) {
      throw new DeveloperError(
        "Invalid arcType. Valid options are ArcType.GEODESIC and ArcType.RHUMB."
      );
    }
    //>>includeEnd('debug');

    var polygonHierarchy = options.polygonHierarchy;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    return computeRectangle$2(
      polygonHierarchy.positions,
      ellipsoid,
      arcType,
      granularity,
      result
    );
  };

  /**
   * Computes the geometric representation of a polygon, including its vertices, indices, and a bounding sphere.
   *
   * @param {PolygonGeometry} polygonGeometry A description of the polygon.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PolygonGeometry.createGeometry = function (polygonGeometry) {
    var vertexFormat = polygonGeometry._vertexFormat;
    var ellipsoid = polygonGeometry._ellipsoid;
    var granularity = polygonGeometry._granularity;
    var stRotation = polygonGeometry._stRotation;
    var polygonHierarchy = polygonGeometry._polygonHierarchy;
    var perPositionHeight = polygonGeometry._perPositionHeight;
    var closeTop = polygonGeometry._closeTop;
    var closeBottom = polygonGeometry._closeBottom;
    var arcType = polygonGeometry._arcType;

    var outerPositions = polygonHierarchy.positions;
    if (outerPositions.length < 3) {
      return;
    }

    var tangentPlane = EllipsoidTangentPlane.fromPoints(
      outerPositions,
      ellipsoid
    );

    var results = PolygonGeometryLibrary.polygonsFromHierarchy(
      polygonHierarchy,
      tangentPlane.projectPointsOntoPlane.bind(tangentPlane),
      !perPositionHeight,
      ellipsoid
    );

    var hierarchy = results.hierarchy;
    var polygons = results.polygons;

    if (hierarchy.length === 0) {
      return;
    }

    outerPositions = hierarchy[0].outerRing;
    var boundingRectangle = PolygonGeometryLibrary.computeBoundingRectangle(
      tangentPlane.plane.normal,
      tangentPlane.projectPointOntoPlane.bind(tangentPlane),
      outerPositions,
      stRotation,
      scratchBoundingRectangle
    );

    var geometries = [];

    var height = polygonGeometry._height;
    var extrudedHeight = polygonGeometry._extrudedHeight;
    var extrude =
      polygonGeometry._perPositionHeightExtrude ||
      !CesiumMath.equalsEpsilon(height, extrudedHeight, 0, CesiumMath.EPSILON2);

    var options = {
      perPositionHeight: perPositionHeight,
      vertexFormat: vertexFormat,
      geometry: undefined,
      tangentPlane: tangentPlane,
      boundingRectangle: boundingRectangle,
      ellipsoid: ellipsoid,
      stRotation: stRotation,
      bottom: false,
      top: true,
      wall: false,
      extrude: false,
      arcType: arcType,
    };

    var i;

    if (extrude) {
      options.extrude = true;
      options.top = closeTop;
      options.bottom = closeBottom;
      options.shadowVolume = polygonGeometry._shadowVolume;
      options.offsetAttribute = polygonGeometry._offsetAttribute;
      for (i = 0; i < polygons.length; i++) {
        var splitGeometry = createGeometryFromPositionsExtruded(
          ellipsoid,
          polygons[i],
          granularity,
          hierarchy[i],
          perPositionHeight,
          closeTop,
          closeBottom,
          vertexFormat,
          arcType
        );

        var topAndBottom;
        if (closeTop && closeBottom) {
          topAndBottom = splitGeometry.topAndBottom;
          options.geometry = PolygonGeometryLibrary.scaleToGeodeticHeightExtruded(
            topAndBottom.geometry,
            height,
            extrudedHeight,
            ellipsoid,
            perPositionHeight
          );
        } else if (closeTop) {
          topAndBottom = splitGeometry.topAndBottom;
          topAndBottom.geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
            topAndBottom.geometry.attributes.position.values,
            height,
            ellipsoid,
            !perPositionHeight
          );
          options.geometry = topAndBottom.geometry;
        } else if (closeBottom) {
          topAndBottom = splitGeometry.topAndBottom;
          topAndBottom.geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
            topAndBottom.geometry.attributes.position.values,
            extrudedHeight,
            ellipsoid,
            true
          );
          options.geometry = topAndBottom.geometry;
        }
        if (closeTop || closeBottom) {
          options.wall = false;
          topAndBottom.geometry = computeAttributes(options);
          geometries.push(topAndBottom);
        }

        var walls = splitGeometry.walls;
        options.wall = true;
        for (var k = 0; k < walls.length; k++) {
          var wall = walls[k];
          options.geometry = PolygonGeometryLibrary.scaleToGeodeticHeightExtruded(
            wall.geometry,
            height,
            extrudedHeight,
            ellipsoid,
            perPositionHeight
          );
          wall.geometry = computeAttributes(options);
          geometries.push(wall);
        }
      }
    } else {
      for (i = 0; i < polygons.length; i++) {
        var geometryInstance = new GeometryInstance({
          geometry: PolygonGeometryLibrary.createGeometryFromPositions(
            ellipsoid,
            polygons[i],
            granularity,
            perPositionHeight,
            vertexFormat,
            arcType
          ),
        });
        geometryInstance.geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
          geometryInstance.geometry.attributes.position.values,
          height,
          ellipsoid,
          !perPositionHeight
        );
        options.geometry = geometryInstance.geometry;
        geometryInstance.geometry = computeAttributes(options);

        if (defined(polygonGeometry._offsetAttribute)) {
          var length =
            geometryInstance.geometry.attributes.position.values.length;
          var applyOffset = new Uint8Array(length / 3);
          var offsetValue =
            polygonGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
              ? 0
              : 1;
          arrayFill(applyOffset, offsetValue);
          geometryInstance.geometry.attributes.applyOffset = new GeometryAttribute(
            {
              componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
              componentsPerAttribute: 1,
              values: applyOffset,
            }
          );
        }

        geometries.push(geometryInstance);
      }
    }

    var geometry = GeometryPipeline.combineInstances(geometries)[0];
    geometry.attributes.position.values = new Float64Array(
      geometry.attributes.position.values
    );
    geometry.indices = IndexDatatype$1.createTypedArray(
      geometry.attributes.position.values.length / 3,
      geometry.indices
    );

    var attributes = geometry.attributes;
    var boundingSphere = BoundingSphere.fromVertices(attributes.position.values);

    if (!vertexFormat.position) {
      delete attributes.position;
    }

    return new Geometry({
      attributes: attributes,
      indices: geometry.indices,
      primitiveType: geometry.primitiveType,
      boundingSphere: boundingSphere,
      offsetAttribute: polygonGeometry._offsetAttribute,
    });
  };

  /**
   * @private
   */
  PolygonGeometry.createShadowVolume = function (
    polygonGeometry,
    minHeightFunc,
    maxHeightFunc
  ) {
    var granularity = polygonGeometry._granularity;
    var ellipsoid = polygonGeometry._ellipsoid;

    var minHeight = minHeightFunc(granularity, ellipsoid);
    var maxHeight = maxHeightFunc(granularity, ellipsoid);

    return new PolygonGeometry({
      polygonHierarchy: polygonGeometry._polygonHierarchy,
      ellipsoid: ellipsoid,
      stRotation: polygonGeometry._stRotation,
      granularity: granularity,
      perPositionHeight: false,
      extrudedHeight: minHeight,
      height: maxHeight,
      vertexFormat: VertexFormat.POSITION_ONLY,
      shadowVolume: true,
      arcType: polygonGeometry._arcType,
    });
  };

  function textureCoordinateRotationPoints$1(polygonGeometry) {
    var stRotation = -polygonGeometry._stRotation;
    if (stRotation === 0.0) {
      return [0, 0, 0, 1, 1, 0];
    }
    var ellipsoid = polygonGeometry._ellipsoid;
    var positions = polygonGeometry._polygonHierarchy.positions;
    var boundingRectangle = polygonGeometry.rectangle;
    return Geometry._textureCoordinateRotationPoints(
      positions,
      stRotation,
      ellipsoid,
      boundingRectangle
    );
  }

  Object.defineProperties(PolygonGeometry.prototype, {
    /**
     * @private
     */
    rectangle: {
      get: function () {
        if (!defined(this._rectangle)) {
          var positions = this._polygonHierarchy.positions;
          this._rectangle = computeRectangle$2(
            positions,
            this._ellipsoid,
            this._arcType,
            this._granularity
          );
        }

        return this._rectangle;
      },
    },
    /**
     * For remapping texture coordinates when rendering PolygonGeometries as GroundPrimitives.
     * @private
     */
    textureCoordinateRotationPoints: {
      get: function () {
        if (!defined(this._textureCoordinateRotationPoints)) {
          this._textureCoordinateRotationPoints = textureCoordinateRotationPoints$1(
            this
          );
        }
        return this._textureCoordinateRotationPoints;
      },
    },
  });

  /**
   * An hierarchy of linear rings which define a polygon and its holes.
   * The holes themselves may also have holes which nest inner polygons.
   * @alias PolygonHierarchy
   * @constructor
   *
   * @param {Cartesian3[]} [positions] A linear ring defining the outer boundary of the polygon or hole.
   * @param {PolygonHierarchy[]} [holes] An array of polygon hierarchies defining holes in the polygon.
   */
  function PolygonHierarchy(positions, holes) {
    /**
     * A linear ring defining the outer boundary of the polygon or hole.
     * @type {Cartesian3[]}
     */
    this.positions = defined(positions) ? positions : [];

    /**
     * An array of polygon hierarchies defining holes in the polygon.
     * @type {PolygonHierarchy[]}
     */
    this.holes = defined(holes) ? holes : [];
  }

  var createGeometryFromPositionsPositions = [];
  var createGeometryFromPositionsSubdivided = [];

  function createGeometryFromPositions$1(
    ellipsoid,
    positions,
    minDistance,
    perPositionHeight,
    arcType
  ) {
    var tangentPlane = EllipsoidTangentPlane.fromPoints(positions, ellipsoid);
    var positions2D = tangentPlane.projectPointsOntoPlane(
      positions,
      createGeometryFromPositionsPositions
    );

    var originalWindingOrder = PolygonPipeline.computeWindingOrder2D(positions2D);
    if (originalWindingOrder === WindingOrder$1.CLOCKWISE) {
      positions2D.reverse();
      positions = positions.slice().reverse();
    }

    var subdividedPositions;
    var i;

    var length = positions.length;
    var index = 0;

    if (!perPositionHeight) {
      var numVertices = 0;
      if (arcType === ArcType$1.GEODESIC) {
        for (i = 0; i < length; i++) {
          numVertices += PolygonGeometryLibrary.subdivideLineCount(
            positions[i],
            positions[(i + 1) % length],
            minDistance
          );
        }
      } else if (arcType === ArcType$1.RHUMB) {
        for (i = 0; i < length; i++) {
          numVertices += PolygonGeometryLibrary.subdivideRhumbLineCount(
            ellipsoid,
            positions[i],
            positions[(i + 1) % length],
            minDistance
          );
        }
      }
      subdividedPositions = new Float64Array(numVertices * 3);
      for (i = 0; i < length; i++) {
        var tempPositions;
        if (arcType === ArcType$1.GEODESIC) {
          tempPositions = PolygonGeometryLibrary.subdivideLine(
            positions[i],
            positions[(i + 1) % length],
            minDistance,
            createGeometryFromPositionsSubdivided
          );
        } else if (arcType === ArcType$1.RHUMB) {
          tempPositions = PolygonGeometryLibrary.subdivideRhumbLine(
            ellipsoid,
            positions[i],
            positions[(i + 1) % length],
            minDistance,
            createGeometryFromPositionsSubdivided
          );
        }
        var tempPositionsLength = tempPositions.length;
        for (var j = 0; j < tempPositionsLength; ++j) {
          subdividedPositions[index++] = tempPositions[j];
        }
      }
    } else {
      subdividedPositions = new Float64Array(length * 2 * 3);
      for (i = 0; i < length; i++) {
        var p0 = positions[i];
        var p1 = positions[(i + 1) % length];
        subdividedPositions[index++] = p0.x;
        subdividedPositions[index++] = p0.y;
        subdividedPositions[index++] = p0.z;
        subdividedPositions[index++] = p1.x;
        subdividedPositions[index++] = p1.y;
        subdividedPositions[index++] = p1.z;
      }
    }

    length = subdividedPositions.length / 3;
    var indicesSize = length * 2;
    var indices = IndexDatatype$1.createTypedArray(length, indicesSize);
    index = 0;
    for (i = 0; i < length - 1; i++) {
      indices[index++] = i;
      indices[index++] = i + 1;
    }
    indices[index++] = length - 1;
    indices[index++] = 0;

    return new GeometryInstance({
      geometry: new Geometry({
        attributes: new GeometryAttributes({
          position: new GeometryAttribute({
            componentDatatype: ComponentDatatype$1.DOUBLE,
            componentsPerAttribute: 3,
            values: subdividedPositions,
          }),
        }),
        indices: indices,
        primitiveType: PrimitiveType$1.LINES,
      }),
    });
  }

  function createGeometryFromPositionsExtruded$1(
    ellipsoid,
    positions,
    minDistance,
    perPositionHeight,
    arcType
  ) {
    var tangentPlane = EllipsoidTangentPlane.fromPoints(positions, ellipsoid);
    var positions2D = tangentPlane.projectPointsOntoPlane(
      positions,
      createGeometryFromPositionsPositions
    );

    var originalWindingOrder = PolygonPipeline.computeWindingOrder2D(positions2D);
    if (originalWindingOrder === WindingOrder$1.CLOCKWISE) {
      positions2D.reverse();
      positions = positions.slice().reverse();
    }

    var subdividedPositions;
    var i;

    var length = positions.length;
    var corners = new Array(length);
    var index = 0;

    if (!perPositionHeight) {
      var numVertices = 0;
      if (arcType === ArcType$1.GEODESIC) {
        for (i = 0; i < length; i++) {
          numVertices += PolygonGeometryLibrary.subdivideLineCount(
            positions[i],
            positions[(i + 1) % length],
            minDistance
          );
        }
      } else if (arcType === ArcType$1.RHUMB) {
        for (i = 0; i < length; i++) {
          numVertices += PolygonGeometryLibrary.subdivideRhumbLineCount(
            ellipsoid,
            positions[i],
            positions[(i + 1) % length],
            minDistance
          );
        }
      }

      subdividedPositions = new Float64Array(numVertices * 3 * 2);
      for (i = 0; i < length; ++i) {
        corners[i] = index / 3;
        var tempPositions;
        if (arcType === ArcType$1.GEODESIC) {
          tempPositions = PolygonGeometryLibrary.subdivideLine(
            positions[i],
            positions[(i + 1) % length],
            minDistance,
            createGeometryFromPositionsSubdivided
          );
        } else if (arcType === ArcType$1.RHUMB) {
          tempPositions = PolygonGeometryLibrary.subdivideRhumbLine(
            ellipsoid,
            positions[i],
            positions[(i + 1) % length],
            minDistance,
            createGeometryFromPositionsSubdivided
          );
        }
        var tempPositionsLength = tempPositions.length;
        for (var j = 0; j < tempPositionsLength; ++j) {
          subdividedPositions[index++] = tempPositions[j];
        }
      }
    } else {
      subdividedPositions = new Float64Array(length * 2 * 3 * 2);
      for (i = 0; i < length; ++i) {
        corners[i] = index / 3;
        var p0 = positions[i];
        var p1 = positions[(i + 1) % length];

        subdividedPositions[index++] = p0.x;
        subdividedPositions[index++] = p0.y;
        subdividedPositions[index++] = p0.z;
        subdividedPositions[index++] = p1.x;
        subdividedPositions[index++] = p1.y;
        subdividedPositions[index++] = p1.z;
      }
    }

    length = subdividedPositions.length / (3 * 2);
    var cornersLength = corners.length;

    var indicesSize = (length * 2 + cornersLength) * 2;
    var indices = IndexDatatype$1.createTypedArray(
      length + cornersLength,
      indicesSize
    );

    index = 0;
    for (i = 0; i < length; ++i) {
      indices[index++] = i;
      indices[index++] = (i + 1) % length;
      indices[index++] = i + length;
      indices[index++] = ((i + 1) % length) + length;
    }

    for (i = 0; i < cornersLength; i++) {
      var corner = corners[i];
      indices[index++] = corner;
      indices[index++] = corner + length;
    }

    return new GeometryInstance({
      geometry: new Geometry({
        attributes: new GeometryAttributes({
          position: new GeometryAttribute({
            componentDatatype: ComponentDatatype$1.DOUBLE,
            componentsPerAttribute: 3,
            values: subdividedPositions,
          }),
        }),
        indices: indices,
        primitiveType: PrimitiveType$1.LINES,
      }),
    });
  }

  /**
   * A description of the outline of a polygon on the ellipsoid. The polygon is defined by a polygon hierarchy.
   *
   * @alias PolygonOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {PolygonHierarchy} options.polygonHierarchy A polygon hierarchy that can include holes.
   * @param {Number} [options.height=0.0] The distance in meters between the polygon and the ellipsoid surface.
   * @param {Number} [options.extrudedHeight] The distance in meters between the polygon's extruded face and the ellipsoid surface.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Boolean} [options.perPositionHeight=false] Use the height of options.positions for each position instead of using options.height to determine the height.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of path the outline must follow. Valid options are {@link ArcType.GEODESIC} and {@link ArcType.RHUMB}.
   *
   * @see PolygonOutlineGeometry#createGeometry
   * @see PolygonOutlineGeometry#fromPositions
   *
   * @example
   * // 1. create a polygon outline from points
   * var polygon = new Cesium.PolygonOutlineGeometry({
   *   polygonHierarchy : new Cesium.PolygonHierarchy(
   *     Cesium.Cartesian3.fromDegreesArray([
   *       -72.0, 40.0,
   *       -70.0, 35.0,
   *       -75.0, 30.0,
   *       -70.0, 30.0,
   *       -68.0, 40.0
   *     ])
   *   )
   * });
   * var geometry = Cesium.PolygonOutlineGeometry.createGeometry(polygon);
   *
   * // 2. create a nested polygon with holes outline
   * var polygonWithHole = new Cesium.PolygonOutlineGeometry({
   *   polygonHierarchy : new Cesium.PolygonHierarchy(
   *     Cesium.Cartesian3.fromDegreesArray([
   *       -109.0, 30.0,
   *       -95.0, 30.0,
   *       -95.0, 40.0,
   *       -109.0, 40.0
   *     ]),
   *     [new Cesium.PolygonHierarchy(
   *       Cesium.Cartesian3.fromDegreesArray([
   *         -107.0, 31.0,
   *         -107.0, 39.0,
   *         -97.0, 39.0,
   *         -97.0, 31.0
   *       ]),
   *       [new Cesium.PolygonHierarchy(
   *         Cesium.Cartesian3.fromDegreesArray([
   *           -105.0, 33.0,
   *           -99.0, 33.0,
   *           -99.0, 37.0,
   *           -105.0, 37.0
   *         ]),
   *         [new Cesium.PolygonHierarchy(
   *           Cesium.Cartesian3.fromDegreesArray([
   *             -103.0, 34.0,
   *             -101.0, 34.0,
   *             -101.0, 36.0,
   *             -103.0, 36.0
   *           ])
   *         )]
   *       )]
   *     )]
   *   )
   * });
   * var geometry = Cesium.PolygonOutlineGeometry.createGeometry(polygonWithHole);
   *
   * // 3. create extruded polygon outline
   * var extrudedPolygon = new Cesium.PolygonOutlineGeometry({
   *   polygonHierarchy : new Cesium.PolygonHierarchy(
   *     Cesium.Cartesian3.fromDegreesArray([
   *       -72.0, 40.0,
   *       -70.0, 35.0,
   *       -75.0, 30.0,
   *       -70.0, 30.0,
   *       -68.0, 40.0
   *     ])
   *   ),
   *   extrudedHeight: 300000
   * });
   * var geometry = Cesium.PolygonOutlineGeometry.createGeometry(extrudedPolygon);
   */
  function PolygonOutlineGeometry(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.polygonHierarchy", options.polygonHierarchy);

    if (options.perPositionHeight && defined(options.height)) {
      throw new DeveloperError(
        "Cannot use both options.perPositionHeight and options.height"
      );
    }
    if (
      defined(options.arcType) &&
      options.arcType !== ArcType$1.GEODESIC &&
      options.arcType !== ArcType$1.RHUMB
    ) {
      throw new DeveloperError(
        "Invalid arcType. Valid options are ArcType.GEODESIC and ArcType.RHUMB."
      );
    }
    //>>includeEnd('debug');

    var polygonHierarchy = options.polygonHierarchy;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var perPositionHeight = defaultValue(options.perPositionHeight, false);
    var perPositionHeightExtrude =
      perPositionHeight && defined(options.extrudedHeight);
    var arcType = defaultValue(options.arcType, ArcType$1.GEODESIC);

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    if (!perPositionHeightExtrude) {
      var h = Math.max(height, extrudedHeight);
      extrudedHeight = Math.min(height, extrudedHeight);
      height = h;
    }

    this._ellipsoid = Ellipsoid.clone(ellipsoid);
    this._granularity = granularity;
    this._height = height;
    this._extrudedHeight = extrudedHeight;
    this._arcType = arcType;
    this._polygonHierarchy = polygonHierarchy;
    this._perPositionHeight = perPositionHeight;
    this._perPositionHeightExtrude = perPositionHeightExtrude;
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createPolygonOutlineGeometry";

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      PolygonGeometryLibrary.computeHierarchyPackedLength(polygonHierarchy) +
      Ellipsoid.packedLength +
      8;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PolygonOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PolygonOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    startingIndex = PolygonGeometryLibrary.packPolygonHierarchy(
      value._polygonHierarchy,
      array,
      startingIndex
    );

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex++] = value._height;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._perPositionHeightExtrude ? 1.0 : 0.0;
    array[startingIndex++] = value._perPositionHeight ? 1.0 : 0.0;
    array[startingIndex++] = value._arcType;
    array[startingIndex++] = defaultValue(value._offsetAttribute, -1);
    array[startingIndex] = value.packedLength;

    return array;
  };

  var scratchEllipsoid$6 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var dummyOptions$1 = {
    polygonHierarchy: {},
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PolygonOutlineGeometry} [result] The object into which to store the result.
   * @returns {PolygonOutlineGeometry} The modified result parameter or a new PolygonOutlineGeometry instance if one was not provided.
   */
  PolygonOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var polygonHierarchy = PolygonGeometryLibrary.unpackPolygonHierarchy(
      array,
      startingIndex
    );
    startingIndex = polygonHierarchy.startingIndex;
    delete polygonHierarchy.startingIndex;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$6);
    startingIndex += Ellipsoid.packedLength;

    var height = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var granularity = array[startingIndex++];
    var perPositionHeightExtrude = array[startingIndex++] === 1.0;
    var perPositionHeight = array[startingIndex++] === 1.0;
    var arcType = array[startingIndex++];
    var offsetAttribute = array[startingIndex++];
    var packedLength = array[startingIndex];

    if (!defined(result)) {
      result = new PolygonOutlineGeometry(dummyOptions$1);
    }

    result._polygonHierarchy = polygonHierarchy;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._height = height;
    result._extrudedHeight = extrudedHeight;
    result._granularity = granularity;
    result._perPositionHeight = perPositionHeight;
    result._perPositionHeightExtrude = perPositionHeightExtrude;
    result._arcType = arcType;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;
    result.packedLength = packedLength;

    return result;
  };

  /**
   * A description of a polygon outline from an array of positions.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of positions that defined the corner points of the polygon.
   * @param {Number} [options.height=0.0] The height of the polygon.
   * @param {Number} [options.extrudedHeight] The height of the polygon extrusion.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Boolean} [options.perPositionHeight=false] Use the height of options.positions for each position instead of using options.height to determine the height.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of path the outline must follow. Valid options are {@link LinkType.GEODESIC} and {@link ArcType.RHUMB}.
   * @returns {PolygonOutlineGeometry}
   *
   *
   * @example
   * // create a polygon from points
   * var polygon = Cesium.PolygonOutlineGeometry.fromPositions({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     -72.0, 40.0,
   *     -70.0, 35.0,
   *     -75.0, 30.0,
   *     -70.0, 30.0,
   *     -68.0, 40.0
   *   ])
   * });
   * var geometry = Cesium.PolygonOutlineGeometry.createGeometry(polygon);
   *
   * @see PolygonOutlineGeometry#createGeometry
   */
  PolygonOutlineGeometry.fromPositions = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.positions", options.positions);
    //>>includeEnd('debug');

    var newOptions = {
      polygonHierarchy: {
        positions: options.positions,
      },
      height: options.height,
      extrudedHeight: options.extrudedHeight,
      ellipsoid: options.ellipsoid,
      granularity: options.granularity,
      perPositionHeight: options.perPositionHeight,
      arcType: options.arcType,
      offsetAttribute: options.offsetAttribute,
    };
    return new PolygonOutlineGeometry(newOptions);
  };

  /**
   * Computes the geometric representation of a polygon outline, including its vertices, indices, and a bounding sphere.
   *
   * @param {PolygonOutlineGeometry} polygonGeometry A description of the polygon outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PolygonOutlineGeometry.createGeometry = function (polygonGeometry) {
    var ellipsoid = polygonGeometry._ellipsoid;
    var granularity = polygonGeometry._granularity;
    var polygonHierarchy = polygonGeometry._polygonHierarchy;
    var perPositionHeight = polygonGeometry._perPositionHeight;
    var arcType = polygonGeometry._arcType;

    var polygons = PolygonGeometryLibrary.polygonOutlinesFromHierarchy(
      polygonHierarchy,
      !perPositionHeight,
      ellipsoid
    );

    if (polygons.length === 0) {
      return undefined;
    }

    var geometryInstance;
    var geometries = [];
    var minDistance = CesiumMath.chordLength(
      granularity,
      ellipsoid.maximumRadius
    );

    var height = polygonGeometry._height;
    var extrudedHeight = polygonGeometry._extrudedHeight;
    var extrude =
      polygonGeometry._perPositionHeightExtrude ||
      !CesiumMath.equalsEpsilon(height, extrudedHeight, 0, CesiumMath.EPSILON2);
    var offsetValue;
    var i;
    if (extrude) {
      for (i = 0; i < polygons.length; i++) {
        geometryInstance = createGeometryFromPositionsExtruded$1(
          ellipsoid,
          polygons[i],
          minDistance,
          perPositionHeight,
          arcType
        );
        geometryInstance.geometry = PolygonGeometryLibrary.scaleToGeodeticHeightExtruded(
          geometryInstance.geometry,
          height,
          extrudedHeight,
          ellipsoid,
          perPositionHeight
        );
        if (defined(polygonGeometry._offsetAttribute)) {
          var size =
            geometryInstance.geometry.attributes.position.values.length / 3;
          var offsetAttribute = new Uint8Array(size);
          if (polygonGeometry._offsetAttribute === GeometryOffsetAttribute$1.TOP) {
            offsetAttribute = arrayFill(offsetAttribute, 1, 0, size / 2);
          } else {
            offsetValue =
              polygonGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
                ? 0
                : 1;
            offsetAttribute = arrayFill(offsetAttribute, offsetValue);
          }

          geometryInstance.geometry.attributes.applyOffset = new GeometryAttribute(
            {
              componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
              componentsPerAttribute: 1,
              values: offsetAttribute,
            }
          );
        }
        geometries.push(geometryInstance);
      }
    } else {
      for (i = 0; i < polygons.length; i++) {
        geometryInstance = createGeometryFromPositions$1(
          ellipsoid,
          polygons[i],
          minDistance,
          perPositionHeight,
          arcType
        );
        geometryInstance.geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
          geometryInstance.geometry.attributes.position.values,
          height,
          ellipsoid,
          !perPositionHeight
        );

        if (defined(polygonGeometry._offsetAttribute)) {
          var length =
            geometryInstance.geometry.attributes.position.values.length;
          var applyOffset = new Uint8Array(length / 3);
          offsetValue =
            polygonGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
              ? 0
              : 1;
          arrayFill(applyOffset, offsetValue);
          geometryInstance.geometry.attributes.applyOffset = new GeometryAttribute(
            {
              componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
              componentsPerAttribute: 1,
              values: applyOffset,
            }
          );
        }

        geometries.push(geometryInstance);
      }
    }

    var geometry = GeometryPipeline.combineInstances(geometries)[0];
    var boundingSphere = BoundingSphere.fromVertices(
      geometry.attributes.position.values
    );

    return new Geometry({
      attributes: geometry.attributes,
      indices: geometry.indices,
      primitiveType: geometry.primitiveType,
      boundingSphere: boundingSphere,
      offsetAttribute: polygonGeometry._offsetAttribute,
    });
  };

  var scratchInterpolateColorsArray = [];

  function interpolateColors(p0, p1, color0, color1, numPoints) {
    var colors = scratchInterpolateColorsArray;
    colors.length = numPoints;
    var i;

    var r0 = color0.red;
    var g0 = color0.green;
    var b0 = color0.blue;
    var a0 = color0.alpha;

    var r1 = color1.red;
    var g1 = color1.green;
    var b1 = color1.blue;
    var a1 = color1.alpha;

    if (Color.equals(color0, color1)) {
      for (i = 0; i < numPoints; i++) {
        colors[i] = Color.clone(color0);
      }
      return colors;
    }

    var redPerVertex = (r1 - r0) / numPoints;
    var greenPerVertex = (g1 - g0) / numPoints;
    var bluePerVertex = (b1 - b0) / numPoints;
    var alphaPerVertex = (a1 - a0) / numPoints;

    for (i = 0; i < numPoints; i++) {
      colors[i] = new Color(
        r0 + i * redPerVertex,
        g0 + i * greenPerVertex,
        b0 + i * bluePerVertex,
        a0 + i * alphaPerVertex
      );
    }

    return colors;
  }

  /**
   * A description of a polyline modeled as a line strip; the first two positions define a line segment,
   * and each additional position defines a line segment from the previous position. The polyline is capable of
   * displaying with a material.
   *
   * @alias PolylineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of {@link Cartesian3} defining the positions in the polyline as a line strip.
   * @param {Number} [options.width=1.0] The width in pixels.
   * @param {Color[]} [options.colors] An Array of {@link Color} defining the per vertex or per segment colors.
   * @param {Boolean} [options.colorsPerVertex=false] A boolean that determines whether the colors will be flat across each segment of the line or interpolated across the vertices.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of line the polyline segments must follow.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude if options.arcType is not ArcType.NONE. Determines the number of positions in the buffer.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   *
   * @exception {DeveloperError} At least two positions are required.
   * @exception {DeveloperError} width must be greater than or equal to one.
   * @exception {DeveloperError} colors has an invalid length.
   *
   * @see PolylineGeometry#createGeometry
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Polyline.html|Cesium Sandcastle Polyline Demo}
   *
   * @example
   * // A polyline with two connected line segments
   * var polyline = new Cesium.PolylineGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     0.0, 0.0,
   *     5.0, 0.0,
   *     5.0, 5.0
   *   ]),
   *   width : 10.0
   * });
   * var geometry = Cesium.PolylineGeometry.createGeometry(polyline);
   */
  function PolylineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;
    var colors = options.colors;
    var width = defaultValue(options.width, 1.0);
    var colorsPerVertex = defaultValue(options.colorsPerVertex, false);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions) || positions.length < 2) {
      throw new DeveloperError("At least two positions are required.");
    }
    if (typeof width !== "number") {
      throw new DeveloperError("width must be a number");
    }
    if (
      defined(colors) &&
      ((colorsPerVertex && colors.length < positions.length) ||
        (!colorsPerVertex && colors.length < positions.length - 1))
    ) {
      throw new DeveloperError("colors has an invalid length.");
    }
    //>>includeEnd('debug');

    this._positions = positions;
    this._colors = colors;
    this._width = width;
    this._colorsPerVertex = colorsPerVertex;
    this._vertexFormat = VertexFormat.clone(
      defaultValue(options.vertexFormat, VertexFormat.DEFAULT)
    );

    this._arcType = defaultValue(options.arcType, ArcType$1.GEODESIC);
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._workerName = "createPolylineGeometry";

    var numComponents = 1 + positions.length * Cartesian3.packedLength;
    numComponents += defined(colors) ? 1 + colors.length * Color.packedLength : 1;

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      numComponents + Ellipsoid.packedLength + VertexFormat.packedLength + 4;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PolylineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PolylineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    var colors = value._colors;
    length = defined(colors) ? colors.length : 0.0;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Color.packedLength) {
      Color.pack(colors[i], array, startingIndex);
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._width;
    array[startingIndex++] = value._colorsPerVertex ? 1.0 : 0.0;
    array[startingIndex++] = value._arcType;
    array[startingIndex] = value._granularity;

    return array;
  };

  var scratchEllipsoid$7 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchVertexFormat$9 = new VertexFormat();
  var scratchOptions$f = {
    positions: undefined,
    colors: undefined,
    ellipsoid: scratchEllipsoid$7,
    vertexFormat: scratchVertexFormat$9,
    width: undefined,
    colorsPerVertex: undefined,
    arcType: undefined,
    granularity: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PolylineGeometry} [result] The object into which to store the result.
   * @returns {PolylineGeometry} The modified result parameter or a new PolylineGeometry instance if one was not provided.
   */
  PolylineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    length = array[startingIndex++];
    var colors = length > 0 ? new Array(length) : undefined;

    for (i = 0; i < length; ++i, startingIndex += Color.packedLength) {
      colors[i] = Color.unpack(array, startingIndex);
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$7);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$9
    );
    startingIndex += VertexFormat.packedLength;

    var width = array[startingIndex++];
    var colorsPerVertex = array[startingIndex++] === 1.0;
    var arcType = array[startingIndex++];
    var granularity = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$f.positions = positions;
      scratchOptions$f.colors = colors;
      scratchOptions$f.width = width;
      scratchOptions$f.colorsPerVertex = colorsPerVertex;
      scratchOptions$f.arcType = arcType;
      scratchOptions$f.granularity = granularity;
      return new PolylineGeometry(scratchOptions$f);
    }

    result._positions = positions;
    result._colors = colors;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._width = width;
    result._colorsPerVertex = colorsPerVertex;
    result._arcType = arcType;
    result._granularity = granularity;

    return result;
  };

  var scratchCartesian3$8 = new Cartesian3();
  var scratchPosition$4 = new Cartesian3();
  var scratchPrevPosition = new Cartesian3();
  var scratchNextPosition = new Cartesian3();

  /**
   * Computes the geometric representation of a polyline, including its vertices, indices, and a bounding sphere.
   *
   * @param {PolylineGeometry} polylineGeometry A description of the polyline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PolylineGeometry.createGeometry = function (polylineGeometry) {
    var width = polylineGeometry._width;
    var vertexFormat = polylineGeometry._vertexFormat;
    var colors = polylineGeometry._colors;
    var colorsPerVertex = polylineGeometry._colorsPerVertex;
    var arcType = polylineGeometry._arcType;
    var granularity = polylineGeometry._granularity;
    var ellipsoid = polylineGeometry._ellipsoid;

    var i;
    var j;
    var k;

    var positions = arrayRemoveDuplicates(
      polylineGeometry._positions,
      Cartesian3.equalsEpsilon
    );
    var positionsLength = positions.length;

    // A width of a pixel or less is not a valid geometry, but in order to support external data
    // that may have errors we treat this as an empty geometry.
    if (positionsLength < 2 || width <= 0.0) {
      return undefined;
    }

    if (arcType === ArcType$1.GEODESIC || arcType === ArcType$1.RHUMB) {
      var subdivisionSize;
      var numberOfPointsFunction;
      if (arcType === ArcType$1.GEODESIC) {
        subdivisionSize = CesiumMath.chordLength(
          granularity,
          ellipsoid.maximumRadius
        );
        numberOfPointsFunction = PolylinePipeline.numberOfPoints;
      } else {
        subdivisionSize = granularity;
        numberOfPointsFunction = PolylinePipeline.numberOfPointsRhumbLine;
      }

      var heights = PolylinePipeline.extractHeights(positions, ellipsoid);

      if (defined(colors)) {
        var colorLength = 1;
        for (i = 0; i < positionsLength - 1; ++i) {
          colorLength += numberOfPointsFunction(
            positions[i],
            positions[i + 1],
            subdivisionSize
          );
        }

        var newColors = new Array(colorLength);
        var newColorIndex = 0;

        for (i = 0; i < positionsLength - 1; ++i) {
          var p0 = positions[i];
          var p1 = positions[i + 1];
          var c0 = colors[i];

          var numColors = numberOfPointsFunction(p0, p1, subdivisionSize);
          if (colorsPerVertex && i < colorLength) {
            var c1 = colors[i + 1];
            var interpolatedColors = interpolateColors(p0, p1, c0, c1, numColors);
            var interpolatedColorsLength = interpolatedColors.length;
            for (j = 0; j < interpolatedColorsLength; ++j) {
              newColors[newColorIndex++] = interpolatedColors[j];
            }
          } else {
            for (j = 0; j < numColors; ++j) {
              newColors[newColorIndex++] = Color.clone(c0);
            }
          }
        }

        newColors[newColorIndex] = Color.clone(colors[colors.length - 1]);
        colors = newColors;

        scratchInterpolateColorsArray.length = 0;
      }

      if (arcType === ArcType$1.GEODESIC) {
        positions = PolylinePipeline.generateCartesianArc({
          positions: positions,
          minDistance: subdivisionSize,
          ellipsoid: ellipsoid,
          height: heights,
        });
      } else {
        positions = PolylinePipeline.generateCartesianRhumbArc({
          positions: positions,
          granularity: subdivisionSize,
          ellipsoid: ellipsoid,
          height: heights,
        });
      }
    }

    positionsLength = positions.length;
    var size = positionsLength * 4.0 - 4.0;

    var finalPositions = new Float64Array(size * 3);
    var prevPositions = new Float64Array(size * 3);
    var nextPositions = new Float64Array(size * 3);
    var expandAndWidth = new Float32Array(size * 2);
    var st = vertexFormat.st ? new Float32Array(size * 2) : undefined;
    var finalColors = defined(colors) ? new Uint8Array(size * 4) : undefined;

    var positionIndex = 0;
    var expandAndWidthIndex = 0;
    var stIndex = 0;
    var colorIndex = 0;
    var position;

    for (j = 0; j < positionsLength; ++j) {
      if (j === 0) {
        position = scratchCartesian3$8;
        Cartesian3.subtract(positions[0], positions[1], position);
        Cartesian3.add(positions[0], position, position);
      } else {
        position = positions[j - 1];
      }

      Cartesian3.clone(position, scratchPrevPosition);
      Cartesian3.clone(positions[j], scratchPosition$4);

      if (j === positionsLength - 1) {
        position = scratchCartesian3$8;
        Cartesian3.subtract(
          positions[positionsLength - 1],
          positions[positionsLength - 2],
          position
        );
        Cartesian3.add(positions[positionsLength - 1], position, position);
      } else {
        position = positions[j + 1];
      }

      Cartesian3.clone(position, scratchNextPosition);

      var color0, color1;
      if (defined(finalColors)) {
        if (j !== 0 && !colorsPerVertex) {
          color0 = colors[j - 1];
        } else {
          color0 = colors[j];
        }

        if (j !== positionsLength - 1) {
          color1 = colors[j];
        }
      }

      var startK = j === 0 ? 2 : 0;
      var endK = j === positionsLength - 1 ? 2 : 4;

      for (k = startK; k < endK; ++k) {
        Cartesian3.pack(scratchPosition$4, finalPositions, positionIndex);
        Cartesian3.pack(scratchPrevPosition, prevPositions, positionIndex);
        Cartesian3.pack(scratchNextPosition, nextPositions, positionIndex);
        positionIndex += 3;

        var direction = k - 2 < 0 ? -1.0 : 1.0;
        expandAndWidth[expandAndWidthIndex++] = 2 * (k % 2) - 1; // expand direction
        expandAndWidth[expandAndWidthIndex++] = direction * width;

        if (vertexFormat.st) {
          st[stIndex++] = j / (positionsLength - 1);
          st[stIndex++] = Math.max(expandAndWidth[expandAndWidthIndex - 2], 0.0);
        }

        if (defined(finalColors)) {
          var color = k < 2 ? color0 : color1;

          finalColors[colorIndex++] = Color.floatToByte(color.red);
          finalColors[colorIndex++] = Color.floatToByte(color.green);
          finalColors[colorIndex++] = Color.floatToByte(color.blue);
          finalColors[colorIndex++] = Color.floatToByte(color.alpha);
        }
      }
    }

    var attributes = new GeometryAttributes();

    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: finalPositions,
    });

    attributes.prevPosition = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: prevPositions,
    });

    attributes.nextPosition = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: nextPositions,
    });

    attributes.expandAndWidth = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 2,
      values: expandAndWidth,
    });

    if (vertexFormat.st) {
      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: st,
      });
    }

    if (defined(finalColors)) {
      attributes.color = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 4,
        values: finalColors,
        normalize: true,
      });
    }

    var indices = IndexDatatype$1.createTypedArray(size, positionsLength * 6 - 6);
    var index = 0;
    var indicesIndex = 0;
    var length = positionsLength - 1.0;
    for (j = 0; j < length; ++j) {
      indices[indicesIndex++] = index;
      indices[indicesIndex++] = index + 2;
      indices[indicesIndex++] = index + 1;

      indices[indicesIndex++] = index + 1;
      indices[indicesIndex++] = index + 2;
      indices[indicesIndex++] = index + 3;

      index += 4;
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: BoundingSphere.fromPoints(positions),
      geometryType: GeometryType$1.POLYLINES,
    });
  };

  function computeAttributes$1(
    combinedPositions,
    shape,
    boundingRectangle,
    vertexFormat
  ) {
    var attributes = new GeometryAttributes();
    if (vertexFormat.position) {
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: combinedPositions,
      });
    }
    var shapeLength = shape.length;
    var vertexCount = combinedPositions.length / 3;
    var length = (vertexCount - shapeLength * 2) / (shapeLength * 2);
    var firstEndIndices = PolygonPipeline.triangulate(shape);

    var indicesCount =
      (length - 1) * shapeLength * 6 + firstEndIndices.length * 2;
    var indices = IndexDatatype$1.createTypedArray(vertexCount, indicesCount);
    var i, j;
    var ll, ul, ur, lr;
    var offset = shapeLength * 2;
    var index = 0;
    for (i = 0; i < length - 1; i++) {
      for (j = 0; j < shapeLength - 1; j++) {
        ll = j * 2 + i * shapeLength * 2;
        lr = ll + offset;
        ul = ll + 1;
        ur = ul + offset;

        indices[index++] = ul;
        indices[index++] = ll;
        indices[index++] = ur;
        indices[index++] = ur;
        indices[index++] = ll;
        indices[index++] = lr;
      }
      ll = shapeLength * 2 - 2 + i * shapeLength * 2;
      ul = ll + 1;
      ur = ul + offset;
      lr = ll + offset;

      indices[index++] = ul;
      indices[index++] = ll;
      indices[index++] = ur;
      indices[index++] = ur;
      indices[index++] = ll;
      indices[index++] = lr;
    }

    if (vertexFormat.st || vertexFormat.tangent || vertexFormat.bitangent) {
      // st required for tangent/bitangent calculation
      var st = new Float32Array(vertexCount * 2);
      var lengthSt = 1 / (length - 1);
      var heightSt = 1 / boundingRectangle.height;
      var heightOffset = boundingRectangle.height / 2;
      var s, t;
      var stindex = 0;
      for (i = 0; i < length; i++) {
        s = i * lengthSt;
        t = heightSt * (shape[0].y + heightOffset);
        st[stindex++] = s;
        st[stindex++] = t;
        for (j = 1; j < shapeLength; j++) {
          t = heightSt * (shape[j].y + heightOffset);
          st[stindex++] = s;
          st[stindex++] = t;
          st[stindex++] = s;
          st[stindex++] = t;
        }
        t = heightSt * (shape[0].y + heightOffset);
        st[stindex++] = s;
        st[stindex++] = t;
      }
      for (j = 0; j < shapeLength; j++) {
        s = 0;
        t = heightSt * (shape[j].y + heightOffset);
        st[stindex++] = s;
        st[stindex++] = t;
      }
      for (j = 0; j < shapeLength; j++) {
        s = (length - 1) * lengthSt;
        t = heightSt * (shape[j].y + heightOffset);
        st[stindex++] = s;
        st[stindex++] = t;
      }

      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: new Float32Array(st),
      });
    }

    var endOffset = vertexCount - shapeLength * 2;
    for (i = 0; i < firstEndIndices.length; i += 3) {
      var v0 = firstEndIndices[i] + endOffset;
      var v1 = firstEndIndices[i + 1] + endOffset;
      var v2 = firstEndIndices[i + 2] + endOffset;

      indices[index++] = v0;
      indices[index++] = v1;
      indices[index++] = v2;
      indices[index++] = v2 + shapeLength;
      indices[index++] = v1 + shapeLength;
      indices[index++] = v0 + shapeLength;
    }

    var geometry = new Geometry({
      attributes: attributes,
      indices: indices,
      boundingSphere: BoundingSphere.fromVertices(combinedPositions),
      primitiveType: PrimitiveType$1.TRIANGLES,
    });

    if (vertexFormat.normal) {
      geometry = GeometryPipeline.computeNormal(geometry);
    }

    if (vertexFormat.tangent || vertexFormat.bitangent) {
      try {
        geometry = GeometryPipeline.computeTangentAndBitangent(geometry);
      } catch (e) {
        oneTimeWarning(
          "polyline-volume-tangent-bitangent",
          "Unable to compute tangents and bitangents for polyline volume geometry"
        );
        //TODO https://github.com/CesiumGS/cesium/issues/3609
      }

      if (!vertexFormat.tangent) {
        geometry.attributes.tangent = undefined;
      }
      if (!vertexFormat.bitangent) {
        geometry.attributes.bitangent = undefined;
      }
      if (!vertexFormat.st) {
        geometry.attributes.st = undefined;
      }
    }

    return geometry;
  }

  /**
   * A description of a polyline with a volume (a 2D shape extruded along a polyline).
   *
   * @alias PolylineVolumeGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.polylinePositions An array of {@link Cartesain3} positions that define the center of the polyline volume.
   * @param {Cartesian2[]} options.shapePositions An array of {@link Cartesian2} positions that define the shape to be extruded along the polyline
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {CornerType} [options.cornerType=CornerType.ROUNDED] Determines the style of the corners.
   *
   * @see PolylineVolumeGeometry#createGeometry
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Polyline%20Volume.html|Cesium Sandcastle Polyline Volume Demo}
   *
   * @example
   * function computeCircle(radius) {
   *   var positions = [];
   *   for (var i = 0; i < 360; i++) {
   *     var radians = Cesium.Math.toRadians(i);
   *     positions.push(new Cesium.Cartesian2(radius * Math.cos(radians), radius * Math.sin(radians)));
   *   }
   *   return positions;
   * }
   *
   * var volume = new Cesium.PolylineVolumeGeometry({
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY,
   *   polylinePositions : Cesium.Cartesian3.fromDegreesArray([
   *     -72.0, 40.0,
   *     -70.0, 35.0
   *   ]),
   *   shapePositions : computeCircle(100000.0)
   * });
   */
  function PolylineVolumeGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.polylinePositions;
    var shape = options.shapePositions;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions)) {
      throw new DeveloperError("options.polylinePositions is required.");
    }
    if (!defined(shape)) {
      throw new DeveloperError("options.shapePositions is required.");
    }
    //>>includeEnd('debug');

    this._positions = positions;
    this._shape = shape;
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._cornerType = defaultValue(options.cornerType, CornerType$1.ROUNDED);
    this._vertexFormat = VertexFormat.clone(
      defaultValue(options.vertexFormat, VertexFormat.DEFAULT)
    );
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._workerName = "createPolylineVolumeGeometry";

    var numComponents = 1 + positions.length * Cartesian3.packedLength;
    numComponents += 1 + shape.length * Cartesian2.packedLength;

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      numComponents + Ellipsoid.packedLength + VertexFormat.packedLength + 2;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PolylineVolumeGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PolylineVolumeGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    var shape = value._shape;
    length = shape.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian2.packedLength) {
      Cartesian2.pack(shape[i], array, startingIndex);
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._cornerType;
    array[startingIndex] = value._granularity;

    return array;
  };

  var scratchEllipsoid$8 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchVertexFormat$a = new VertexFormat();
  var scratchOptions$g = {
    polylinePositions: undefined,
    shapePositions: undefined,
    ellipsoid: scratchEllipsoid$8,
    vertexFormat: scratchVertexFormat$a,
    cornerType: undefined,
    granularity: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PolylineVolumeGeometry} [result] The object into which to store the result.
   * @returns {PolylineVolumeGeometry} The modified result parameter or a new PolylineVolumeGeometry instance if one was not provided.
   */
  PolylineVolumeGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    length = array[startingIndex++];
    var shape = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian2.packedLength) {
      shape[i] = Cartesian2.unpack(array, startingIndex);
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$8);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$a
    );
    startingIndex += VertexFormat.packedLength;

    var cornerType = array[startingIndex++];
    var granularity = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$g.polylinePositions = positions;
      scratchOptions$g.shapePositions = shape;
      scratchOptions$g.cornerType = cornerType;
      scratchOptions$g.granularity = granularity;
      return new PolylineVolumeGeometry(scratchOptions$g);
    }

    result._positions = positions;
    result._shape = shape;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._cornerType = cornerType;
    result._granularity = granularity;

    return result;
  };

  var brScratch = new BoundingRectangle();

  /**
   * Computes the geometric representation of a polyline with a volume, including its vertices, indices, and a bounding sphere.
   *
   * @param {PolylineVolumeGeometry} polylineVolumeGeometry A description of the polyline volume.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PolylineVolumeGeometry.createGeometry = function (polylineVolumeGeometry) {
    var positions = polylineVolumeGeometry._positions;
    var cleanPositions = arrayRemoveDuplicates(
      positions,
      Cartesian3.equalsEpsilon
    );
    var shape2D = polylineVolumeGeometry._shape;
    shape2D = PolylineVolumeGeometryLibrary.removeDuplicatesFromShape(shape2D);

    if (cleanPositions.length < 2 || shape2D.length < 3) {
      return undefined;
    }

    if (
      PolygonPipeline.computeWindingOrder2D(shape2D) === WindingOrder$1.CLOCKWISE
    ) {
      shape2D.reverse();
    }
    var boundingRectangle = BoundingRectangle.fromPoints(shape2D, brScratch);

    var computedPositions = PolylineVolumeGeometryLibrary.computePositions(
      cleanPositions,
      shape2D,
      boundingRectangle,
      polylineVolumeGeometry,
      true
    );
    return computeAttributes$1(
      computedPositions,
      shape2D,
      boundingRectangle,
      polylineVolumeGeometry._vertexFormat
    );
  };

  function computeAttributes$2(positions, shape) {
    var attributes = new GeometryAttributes();
    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: positions,
    });

    var shapeLength = shape.length;
    var vertexCount = attributes.position.values.length / 3;
    var positionLength = positions.length / 3;
    var shapeCount = positionLength / shapeLength;
    var indices = IndexDatatype$1.createTypedArray(
      vertexCount,
      2 * shapeLength * (shapeCount + 1)
    );
    var i, j;
    var index = 0;
    i = 0;
    var offset = i * shapeLength;
    for (j = 0; j < shapeLength - 1; j++) {
      indices[index++] = j + offset;
      indices[index++] = j + offset + 1;
    }
    indices[index++] = shapeLength - 1 + offset;
    indices[index++] = offset;

    i = shapeCount - 1;
    offset = i * shapeLength;
    for (j = 0; j < shapeLength - 1; j++) {
      indices[index++] = j + offset;
      indices[index++] = j + offset + 1;
    }
    indices[index++] = shapeLength - 1 + offset;
    indices[index++] = offset;

    for (i = 0; i < shapeCount - 1; i++) {
      var firstOffset = shapeLength * i;
      var secondOffset = firstOffset + shapeLength;
      for (j = 0; j < shapeLength; j++) {
        indices[index++] = j + firstOffset;
        indices[index++] = j + secondOffset;
      }
    }

    var geometry = new Geometry({
      attributes: attributes,
      indices: IndexDatatype$1.createTypedArray(vertexCount, indices),
      boundingSphere: BoundingSphere.fromVertices(positions),
      primitiveType: PrimitiveType$1.LINES,
    });

    return geometry;
  }

  /**
   * A description of a polyline with a volume (a 2D shape extruded along a polyline).
   *
   * @alias PolylineVolumeOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.polylinePositions An array of positions that define the center of the polyline volume.
   * @param {Cartesian2[]} options.shapePositions An array of positions that define the shape to be extruded along the polyline
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {CornerType} [options.cornerType=CornerType.ROUNDED] Determines the style of the corners.
   *
   * @see PolylineVolumeOutlineGeometry#createGeometry
   *
   * @example
   * function computeCircle(radius) {
   *   var positions = [];
   *   for (var i = 0; i < 360; i++) {
   *     var radians = Cesium.Math.toRadians(i);
   *     positions.push(new Cesium.Cartesian2(radius * Math.cos(radians), radius * Math.sin(radians)));
   *   }
   *   return positions;
   * }
   *
   * var volumeOutline = new Cesium.PolylineVolumeOutlineGeometry({
   *   polylinePositions : Cesium.Cartesian3.fromDegreesArray([
   *     -72.0, 40.0,
   *     -70.0, 35.0
   *   ]),
   *   shapePositions : computeCircle(100000.0)
   * });
   */
  function PolylineVolumeOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.polylinePositions;
    var shape = options.shapePositions;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions)) {
      throw new DeveloperError("options.polylinePositions is required.");
    }
    if (!defined(shape)) {
      throw new DeveloperError("options.shapePositions is required.");
    }
    //>>includeEnd('debug');

    this._positions = positions;
    this._shape = shape;
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._cornerType = defaultValue(options.cornerType, CornerType$1.ROUNDED);
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._workerName = "createPolylineVolumeOutlineGeometry";

    var numComponents = 1 + positions.length * Cartesian3.packedLength;
    numComponents += 1 + shape.length * Cartesian2.packedLength;

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength = numComponents + Ellipsoid.packedLength + 2;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {PolylineVolumeOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  PolylineVolumeOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    var shape = value._shape;
    length = shape.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian2.packedLength) {
      Cartesian2.pack(shape[i], array, startingIndex);
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex++] = value._cornerType;
    array[startingIndex] = value._granularity;

    return array;
  };

  var scratchEllipsoid$9 = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchOptions$h = {
    polylinePositions: undefined,
    shapePositions: undefined,
    ellipsoid: scratchEllipsoid$9,
    height: undefined,
    cornerType: undefined,
    granularity: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {PolylineVolumeOutlineGeometry} [result] The object into which to store the result.
   * @returns {PolylineVolumeOutlineGeometry} The modified result parameter or a new PolylineVolumeOutlineGeometry instance if one was not provided.
   */
  PolylineVolumeOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    length = array[startingIndex++];
    var shape = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian2.packedLength) {
      shape[i] = Cartesian2.unpack(array, startingIndex);
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$9);
    startingIndex += Ellipsoid.packedLength;

    var cornerType = array[startingIndex++];
    var granularity = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$h.polylinePositions = positions;
      scratchOptions$h.shapePositions = shape;
      scratchOptions$h.cornerType = cornerType;
      scratchOptions$h.granularity = granularity;
      return new PolylineVolumeOutlineGeometry(scratchOptions$h);
    }

    result._positions = positions;
    result._shape = shape;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._cornerType = cornerType;
    result._granularity = granularity;

    return result;
  };

  var brScratch$1 = new BoundingRectangle();

  /**
   * Computes the geometric representation of the outline of a polyline with a volume, including its vertices, indices, and a bounding sphere.
   *
   * @param {PolylineVolumeOutlineGeometry} polylineVolumeOutlineGeometry A description of the polyline volume outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  PolylineVolumeOutlineGeometry.createGeometry = function (
    polylineVolumeOutlineGeometry
  ) {
    var positions = polylineVolumeOutlineGeometry._positions;
    var cleanPositions = arrayRemoveDuplicates(
      positions,
      Cartesian3.equalsEpsilon
    );
    var shape2D = polylineVolumeOutlineGeometry._shape;
    shape2D = PolylineVolumeGeometryLibrary.removeDuplicatesFromShape(shape2D);

    if (cleanPositions.length < 2 || shape2D.length < 3) {
      return undefined;
    }

    if (
      PolygonPipeline.computeWindingOrder2D(shape2D) === WindingOrder$1.CLOCKWISE
    ) {
      shape2D.reverse();
    }
    var boundingRectangle = BoundingRectangle.fromPoints(shape2D, brScratch$1);

    var computedPositions = PolylineVolumeGeometryLibrary.computePositions(
      cleanPositions,
      shape2D,
      boundingRectangle,
      polylineVolumeOutlineGeometry,
      false
    );
    return computeAttributes$2(computedPositions, shape2D);
  };

  /**
   * Base class for proxying requested made by {@link Resource}.
   *
   * @alias Proxy
   * @constructor
   *
   * @see DefaultProxy
   */
  function Proxy() {
    DeveloperError.throwInstantiationError();
  }

  /**
   * Get the final URL to use to request a given resource.
   *
   * @param {String} resource The resource to request.
   * @returns {String} proxied resource
   * @function
   */
  Proxy.prototype.getURL = DeveloperError.throwInstantiationError;

  function createEvaluateFunction$1(spline) {
    var points = spline.points;
    var times = spline.times;

    // use slerp interpolation
    return function (time, result) {
      if (!defined(result)) {
        result = new Quaternion();
      }
      var i = (spline._lastTimeIndex = spline.findTimeInterval(
        time,
        spline._lastTimeIndex
      ));
      var u = (time - times[i]) / (times[i + 1] - times[i]);

      var q0 = points[i];
      var q1 = points[i + 1];

      return Quaternion.fastSlerp(q0, q1, u, result);
    };
  }

  /**
   * A spline that uses spherical linear (slerp) interpolation to create a quaternion curve.
   * The generated curve is in the class C<sup>1</sup>.
   *
   * @alias QuaternionSpline
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times An array of strictly increasing, unit-less, floating-point times at each point.
   *                The values are in no way connected to the clock time. They are the parameterization for the curve.
   * @param {Quaternion[]} options.points The array of {@link Quaternion} control points.
   *
   * @exception {DeveloperError} points.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be equal to points.length.
   *
   * @see HermiteSpline
   * @see CatmullRomSpline
   * @see LinearSpline
   * @see WeightSpline
   */
  function QuaternionSpline(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var points = options.points;
    var times = options.times;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(points) || !defined(times)) {
      throw new DeveloperError("points and times are required.");
    }
    if (points.length < 2) {
      throw new DeveloperError(
        "points.length must be greater than or equal to 2."
      );
    }
    if (times.length !== points.length) {
      throw new DeveloperError("times.length must be equal to points.length.");
    }
    //>>includeEnd('debug');

    this._times = times;
    this._points = points;

    this._evaluateFunction = createEvaluateFunction$1(this);
    this._lastTimeIndex = 0;
  }

  Object.defineProperties(QuaternionSpline.prototype, {
    /**
     * An array of times for the control points.
     *
     * @memberof QuaternionSpline.prototype
     *
     * @type {Number[]}
     * @readonly
     */
    times: {
      get: function () {
        return this._times;
      },
    },

    /**
     * An array of {@link Quaternion} control points.
     *
     * @memberof QuaternionSpline.prototype
     *
     * @type {Quaternion[]}
     * @readonly
     */
    points: {
      get: function () {
        return this._points;
      },
    },
  });

  /**
   * Finds an index <code>i</code> in <code>times</code> such that the parameter
   * <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
   * @function
   *
   * @param {Number} time The time.
   * @returns {Number} The index for the element at the start of the interval.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  QuaternionSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;

  /**
   * Wraps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, wrapped around to the updated animation.
   */
  QuaternionSpline.prototype.wrapTime = Spline.prototype.wrapTime;

  /**
   * Clamps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, clamped to the animation period.
   */
  QuaternionSpline.prototype.clampTime = Spline.prototype.clampTime;

  /**
   * Evaluates the curve at a given time.
   *
   * @param {Number} time The time at which to evaluate the curve.
   * @param {Quaternion} [result] The object onto which to store the result.
   * @returns {Quaternion} The modified result parameter or a new instance of the point on the curve at the given time.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  QuaternionSpline.prototype.evaluate = function (time, result) {
    return this._evaluateFunction(time, result);
  };

  function quickselect(arr, k, left, right, compare) {
      quickselectStep(arr, k, left || 0, right || (arr.length - 1), compare || defaultCompare);
  }

  function quickselectStep(arr, k, left, right, compare) {

      while (right > left) {
          if (right - left > 600) {
              var n = right - left + 1;
              var m = k - left + 1;
              var z = Math.log(n);
              var s = 0.5 * Math.exp(2 * z / 3);
              var sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1);
              var newLeft = Math.max(left, Math.floor(k - m * s / n + sd));
              var newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd));
              quickselectStep(arr, k, newLeft, newRight, compare);
          }

          var t = arr[k];
          var i = left;
          var j = right;

          swap$1(arr, left, k);
          if (compare(arr[right], t) > 0) { swap$1(arr, left, right); }

          while (i < j) {
              swap$1(arr, i, j);
              i++;
              j--;
              while (compare(arr[i], t) < 0) { i++; }
              while (compare(arr[j], t) > 0) { j--; }
          }

          if (compare(arr[left], t) === 0) { swap$1(arr, left, j); }
          else {
              j++;
              swap$1(arr, j, right);
          }

          if (j <= k) { left = j + 1; }
          if (k <= j) { right = j - 1; }
      }
  }

  function swap$1(arr, i, j) {
      var tmp = arr[i];
      arr[i] = arr[j];
      arr[j] = tmp;
  }

  function defaultCompare(a, b) {
      return a < b ? -1 : a > b ? 1 : 0;
  }

  function RBush(maxEntries) {
      if ( maxEntries === void 0 ) maxEntries = 9;

      // max entries in a node is 9 by default; min node fill is 40% for best performance
      this._maxEntries = Math.max(4, maxEntries);
      this._minEntries = Math.max(2, Math.ceil(this._maxEntries * 0.4));
      this.clear();
  }
  RBush.prototype.all = function all () {
      return this._all(this.data, []);
  };

  RBush.prototype.search = function search (bbox) {
      var node = this.data;
      var result = [];

      if (!intersects$1(bbox, node)) { return result; }

      var toBBox = this.toBBox;
      var nodesToSearch = [];

      while (node) {
          for (var i = 0; i < node.children.length; i++) {
              var child = node.children[i];
              var childBBox = node.leaf ? toBBox(child) : child;

              if (intersects$1(bbox, childBBox)) {
                  if (node.leaf) { result.push(child); }
                  else if (contains(bbox, childBBox)) { this._all(child, result); }
                  else { nodesToSearch.push(child); }
              }
          }
          node = nodesToSearch.pop();
      }

      return result;
  };

  RBush.prototype.collides = function collides (bbox) {
      var node = this.data;

      if (!intersects$1(bbox, node)) { return false; }

      var nodesToSearch = [];
      while (node) {
          for (var i = 0; i < node.children.length; i++) {
              var child = node.children[i];
              var childBBox = node.leaf ? this.toBBox(child) : child;

              if (intersects$1(bbox, childBBox)) {
                  if (node.leaf || contains(bbox, childBBox)) { return true; }
                  nodesToSearch.push(child);
              }
          }
          node = nodesToSearch.pop();
      }

      return false;
  };

  RBush.prototype.load = function load (data) {
      if (!(data && data.length)) { return this; }

      if (data.length < this._minEntries) {
          for (var i = 0; i < data.length; i++) {
              this.insert(data[i]);
          }
          return this;
      }

      // recursively build the tree with the given data from scratch using OMT algorithm
      var node = this._build(data.slice(), 0, data.length - 1, 0);

      if (!this.data.children.length) {
          // save as is if tree is empty
          this.data = node;

      } else if (this.data.height === node.height) {
          // split root if trees have the same height
          this._splitRoot(this.data, node);

      } else {
          if (this.data.height < node.height) {
              // swap trees if inserted one is bigger
              var tmpNode = this.data;
              this.data = node;
              node = tmpNode;
          }

          // insert the small tree into the large tree at appropriate level
          this._insert(node, this.data.height - node.height - 1, true);
      }

      return this;
  };

  RBush.prototype.insert = function insert (item) {
      if (item) { this._insert(item, this.data.height - 1); }
      return this;
  };

  RBush.prototype.clear = function clear () {
      this.data = createNode([]);
      return this;
  };

  RBush.prototype.remove = function remove (item, equalsFn) {
      if (!item) { return this; }

      var node = this.data;
      var bbox = this.toBBox(item);
      var path = [];
      var indexes = [];
      var i, parent, goingUp;

      // depth-first iterative tree traversal
      while (node || path.length) {

          if (!node) { // go up
              node = path.pop();
              parent = path[path.length - 1];
              i = indexes.pop();
              goingUp = true;
          }

          if (node.leaf) { // check current node
              var index = findItem(item, node.children, equalsFn);

              if (index !== -1) {
                  // item found, remove the item and condense tree upwards
                  node.children.splice(index, 1);
                  path.push(node);
                  this._condense(path);
                  return this;
              }
          }

          if (!goingUp && !node.leaf && contains(node, bbox)) { // go down
              path.push(node);
              indexes.push(i);
              i = 0;
              parent = node;
              node = node.children[0];

          } else if (parent) { // go right
              i++;
              node = parent.children[i];
              goingUp = false;

          } else { node = null; } // nothing found
      }

      return this;
  };

  RBush.prototype.toBBox = function toBBox (item) { return item; };

  RBush.prototype.compareMinX = function compareMinX (a, b) { return a.minX - b.minX; };
  RBush.prototype.compareMinY = function compareMinY (a, b) { return a.minY - b.minY; };

  RBush.prototype.toJSON = function toJSON () { return this.data; };

  RBush.prototype.fromJSON = function fromJSON (data) {
      this.data = data;
      return this;
  };

  RBush.prototype._all = function _all (node, result) {
      var nodesToSearch = [];
      while (node) {
          if (node.leaf) { result.push.apply(result, node.children); }
          else { nodesToSearch.push.apply(nodesToSearch, node.children); }

          node = nodesToSearch.pop();
      }
      return result;
  };

  RBush.prototype._build = function _build (items, left, right, height) {

      var N = right - left + 1;
      var M = this._maxEntries;
      var node;

      if (N <= M) {
          // reached leaf level; return leaf
          node = createNode(items.slice(left, right + 1));
          calcBBox(node, this.toBBox);
          return node;
      }

      if (!height) {
          // target height of the bulk-loaded tree
          height = Math.ceil(Math.log(N) / Math.log(M));

          // target number of root entries to maximize storage utilization
          M = Math.ceil(N / Math.pow(M, height - 1));
      }

      node = createNode([]);
      node.leaf = false;
      node.height = height;

      // split the items into M mostly square tiles

      var N2 = Math.ceil(N / M);
      var N1 = N2 * Math.ceil(Math.sqrt(M));

      multiSelect(items, left, right, N1, this.compareMinX);

      for (var i = left; i <= right; i += N1) {

          var right2 = Math.min(i + N1 - 1, right);

          multiSelect(items, i, right2, N2, this.compareMinY);

          for (var j = i; j <= right2; j += N2) {

              var right3 = Math.min(j + N2 - 1, right2);

              // pack each entry recursively
              node.children.push(this._build(items, j, right3, height - 1));
          }
      }

      calcBBox(node, this.toBBox);

      return node;
  };

  RBush.prototype._chooseSubtree = function _chooseSubtree (bbox, node, level, path) {
      while (true) {
          path.push(node);

          if (node.leaf || path.length - 1 === level) { break; }

          var minArea = Infinity;
          var minEnlargement = Infinity;
          var targetNode = (void 0);

          for (var i = 0; i < node.children.length; i++) {
              var child = node.children[i];
              var area = bboxArea(child);
              var enlargement = enlargedArea(bbox, child) - area;

              // choose entry with the least area enlargement
              if (enlargement < minEnlargement) {
                  minEnlargement = enlargement;
                  minArea = area < minArea ? area : minArea;
                  targetNode = child;

              } else if (enlargement === minEnlargement) {
                  // otherwise choose one with the smallest area
                  if (area < minArea) {
                      minArea = area;
                      targetNode = child;
                  }
              }
          }

          node = targetNode || node.children[0];
      }

      return node;
  };

  RBush.prototype._insert = function _insert (item, level, isNode) {
      var bbox = isNode ? item : this.toBBox(item);
      var insertPath = [];

      // find the best node for accommodating the item, saving all nodes along the path too
      var node = this._chooseSubtree(bbox, this.data, level, insertPath);

      // put the item into the node
      node.children.push(item);
      extend(node, bbox);

      // split on node overflow; propagate upwards if necessary
      while (level >= 0) {
          if (insertPath[level].children.length > this._maxEntries) {
              this._split(insertPath, level);
              level--;
          } else { break; }
      }

      // adjust bboxes along the insertion path
      this._adjustParentBBoxes(bbox, insertPath, level);
  };

  // split overflowed node into two
  RBush.prototype._split = function _split (insertPath, level) {
      var node = insertPath[level];
      var M = node.children.length;
      var m = this._minEntries;

      this._chooseSplitAxis(node, m, M);

      var splitIndex = this._chooseSplitIndex(node, m, M);

      var newNode = createNode(node.children.splice(splitIndex, node.children.length - splitIndex));
      newNode.height = node.height;
      newNode.leaf = node.leaf;

      calcBBox(node, this.toBBox);
      calcBBox(newNode, this.toBBox);

      if (level) { insertPath[level - 1].children.push(newNode); }
      else { this._splitRoot(node, newNode); }
  };

  RBush.prototype._splitRoot = function _splitRoot (node, newNode) {
      // split root node
      this.data = createNode([node, newNode]);
      this.data.height = node.height + 1;
      this.data.leaf = false;
      calcBBox(this.data, this.toBBox);
  };

  RBush.prototype._chooseSplitIndex = function _chooseSplitIndex (node, m, M) {
      var index;
      var minOverlap = Infinity;
      var minArea = Infinity;

      for (var i = m; i <= M - m; i++) {
          var bbox1 = distBBox(node, 0, i, this.toBBox);
          var bbox2 = distBBox(node, i, M, this.toBBox);

          var overlap = intersectionArea(bbox1, bbox2);
          var area = bboxArea(bbox1) + bboxArea(bbox2);

          // choose distribution with minimum overlap
          if (overlap < minOverlap) {
              minOverlap = overlap;
              index = i;

              minArea = area < minArea ? area : minArea;

          } else if (overlap === minOverlap) {
              // otherwise choose distribution with minimum area
              if (area < minArea) {
                  minArea = area;
                  index = i;
              }
          }
      }

      return index || M - m;
  };

  // sorts node children by the best axis for split
  RBush.prototype._chooseSplitAxis = function _chooseSplitAxis (node, m, M) {
      var compareMinX = node.leaf ? this.compareMinX : compareNodeMinX;
      var compareMinY = node.leaf ? this.compareMinY : compareNodeMinY;
      var xMargin = this._allDistMargin(node, m, M, compareMinX);
      var yMargin = this._allDistMargin(node, m, M, compareMinY);

      // if total distributions margin value is minimal for x, sort by minX,
      // otherwise it's already sorted by minY
      if (xMargin < yMargin) { node.children.sort(compareMinX); }
  };

  // total margin of all possible split distributions where each node is at least m full
  RBush.prototype._allDistMargin = function _allDistMargin (node, m, M, compare) {
      node.children.sort(compare);

      var toBBox = this.toBBox;
      var leftBBox = distBBox(node, 0, m, toBBox);
      var rightBBox = distBBox(node, M - m, M, toBBox);
      var margin = bboxMargin(leftBBox) + bboxMargin(rightBBox);

      for (var i = m; i < M - m; i++) {
          var child = node.children[i];
          extend(leftBBox, node.leaf ? toBBox(child) : child);
          margin += bboxMargin(leftBBox);
      }

      for (var i$1 = M - m - 1; i$1 >= m; i$1--) {
          var child$1 = node.children[i$1];
          extend(rightBBox, node.leaf ? toBBox(child$1) : child$1);
          margin += bboxMargin(rightBBox);
      }

      return margin;
  };

  RBush.prototype._adjustParentBBoxes = function _adjustParentBBoxes (bbox, path, level) {
      // adjust bboxes along the given tree path
      for (var i = level; i >= 0; i--) {
          extend(path[i], bbox);
      }
  };

  RBush.prototype._condense = function _condense (path) {
      // go through the path, removing empty nodes and updating bboxes
      for (var i = path.length - 1, siblings = (void 0); i >= 0; i--) {
          if (path[i].children.length === 0) {
              if (i > 0) {
                  siblings = path[i - 1].children;
                  siblings.splice(siblings.indexOf(path[i]), 1);

              } else { this.clear(); }

          } else { calcBBox(path[i], this.toBBox); }
      }
  };

  function findItem(item, items, equalsFn) {
      if (!equalsFn) { return items.indexOf(item); }

      for (var i = 0; i < items.length; i++) {
          if (equalsFn(item, items[i])) { return i; }
      }
      return -1;
  }

  // calculate node's bbox from bboxes of its children
  function calcBBox(node, toBBox) {
      distBBox(node, 0, node.children.length, toBBox, node);
  }

  // min bounding rectangle of node children from k to p-1
  function distBBox(node, k, p, toBBox, destNode) {
      if (!destNode) { destNode = createNode(null); }
      destNode.minX = Infinity;
      destNode.minY = Infinity;
      destNode.maxX = -Infinity;
      destNode.maxY = -Infinity;

      for (var i = k; i < p; i++) {
          var child = node.children[i];
          extend(destNode, node.leaf ? toBBox(child) : child);
      }

      return destNode;
  }

  function extend(a, b) {
      a.minX = Math.min(a.minX, b.minX);
      a.minY = Math.min(a.minY, b.minY);
      a.maxX = Math.max(a.maxX, b.maxX);
      a.maxY = Math.max(a.maxY, b.maxY);
      return a;
  }

  function compareNodeMinX(a, b) { return a.minX - b.minX; }
  function compareNodeMinY(a, b) { return a.minY - b.minY; }

  function bboxArea(a)   { return (a.maxX - a.minX) * (a.maxY - a.minY); }
  function bboxMargin(a) { return (a.maxX - a.minX) + (a.maxY - a.minY); }

  function enlargedArea(a, b) {
      return (Math.max(b.maxX, a.maxX) - Math.min(b.minX, a.minX)) *
             (Math.max(b.maxY, a.maxY) - Math.min(b.minY, a.minY));
  }

  function intersectionArea(a, b) {
      var minX = Math.max(a.minX, b.minX);
      var minY = Math.max(a.minY, b.minY);
      var maxX = Math.min(a.maxX, b.maxX);
      var maxY = Math.min(a.maxY, b.maxY);

      return Math.max(0, maxX - minX) *
             Math.max(0, maxY - minY);
  }

  function contains(a, b) {
      return a.minX <= b.minX &&
             a.minY <= b.minY &&
             b.maxX <= a.maxX &&
             b.maxY <= a.maxY;
  }

  function intersects$1(a, b) {
      return b.minX <= a.maxX &&
             b.minY <= a.maxY &&
             b.maxX >= a.minX &&
             b.maxY >= a.minY;
  }

  function createNode(children) {
      return {
          children: children,
          height: 1,
          leaf: true,
          minX: Infinity,
          minY: Infinity,
          maxX: -Infinity,
          maxY: -Infinity
      };
  }

  // sort an array so that items come in groups of n unsorted items, with groups sorted between each other;
  // combines selection algorithm with binary divide & conquer approach

  function multiSelect(arr, left, right, n, compare) {
      var stack = [left, right];

      while (stack.length) {
          right = stack.pop();
          left = stack.pop();

          if (right - left <= n) { continue; }

          var mid = left + Math.ceil((right - left) / n / 2) * n;
          quickselect(arr, mid, left, right, compare);

          stack.push(left, mid, mid, right);
      }
  }

  /**
   * Wrapper around rbush for use with Rectangle types.
   * @private
   */
  function RectangleCollisionChecker() {
    this._tree = new RBush();
  }

  function RectangleWithId() {
    this.minX = 0.0;
    this.minY = 0.0;
    this.maxX = 0.0;
    this.maxY = 0.0;
    this.id = "";
  }

  RectangleWithId.fromRectangleAndId = function (id, rectangle, result) {
    result.minX = rectangle.west;
    result.minY = rectangle.south;
    result.maxX = rectangle.east;
    result.maxY = rectangle.north;
    result.id = id;
    return result;
  };

  /**
   * Insert a rectangle into the collision checker.
   *
   * @param {String} id Unique string ID for the rectangle being inserted.
   * @param {Rectangle} rectangle A Rectangle
   * @private
   */
  RectangleCollisionChecker.prototype.insert = function (id, rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("id", id);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    var withId = RectangleWithId.fromRectangleAndId(
      id,
      rectangle,
      new RectangleWithId()
    );
    this._tree.insert(withId);
  };

  function idCompare(a, b) {
    return a.id === b.id;
  }

  var removalScratch = new RectangleWithId();
  /**
   * Remove a rectangle from the collision checker.
   *
   * @param {String} id Unique string ID for the rectangle being removed.
   * @param {Rectangle} rectangle A Rectangle
   * @private
   */
  RectangleCollisionChecker.prototype.remove = function (id, rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("id", id);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    var withId = RectangleWithId.fromRectangleAndId(
      id,
      rectangle,
      removalScratch
    );
    this._tree.remove(withId, idCompare);
  };

  var collisionScratch = new RectangleWithId();
  /**
   * Checks if a given rectangle collides with any of the rectangles in the collection.
   *
   * @param {Rectangle} rectangle A Rectangle that should be checked against the rectangles in the collision checker.
   * @returns {Boolean} Whether the rectangle collides with any of the rectangles in the collision checker.
   */
  RectangleCollisionChecker.prototype.collides = function (rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    var withId = RectangleWithId.fromRectangleAndId(
      "",
      rectangle,
      collisionScratch
    );
    return this._tree.collides(withId);
  };

  var cos$2 = Math.cos;
  var sin$2 = Math.sin;
  var sqrt = Math.sqrt;

  /**
   * @private
   */
  var RectangleGeometryLibrary = {};

  /**
   * @private
   */
  RectangleGeometryLibrary.computePosition = function (
    computedOptions,
    ellipsoid,
    computeST,
    row,
    col,
    position,
    st
  ) {
    var radiiSquared = ellipsoid.radiiSquared;
    var nwCorner = computedOptions.nwCorner;
    var rectangle = computedOptions.boundingRectangle;

    var stLatitude =
      nwCorner.latitude -
      computedOptions.granYCos * row +
      col * computedOptions.granXSin;
    var cosLatitude = cos$2(stLatitude);
    var nZ = sin$2(stLatitude);
    var kZ = radiiSquared.z * nZ;

    var stLongitude =
      nwCorner.longitude +
      row * computedOptions.granYSin +
      col * computedOptions.granXCos;
    var nX = cosLatitude * cos$2(stLongitude);
    var nY = cosLatitude * sin$2(stLongitude);

    var kX = radiiSquared.x * nX;
    var kY = radiiSquared.y * nY;

    var gamma = sqrt(kX * nX + kY * nY + kZ * nZ);

    position.x = kX / gamma;
    position.y = kY / gamma;
    position.z = kZ / gamma;

    if (computeST) {
      var stNwCorner = computedOptions.stNwCorner;
      if (defined(stNwCorner)) {
        stLatitude =
          stNwCorner.latitude -
          computedOptions.stGranYCos * row +
          col * computedOptions.stGranXSin;
        stLongitude =
          stNwCorner.longitude +
          row * computedOptions.stGranYSin +
          col * computedOptions.stGranXCos;

        st.x = (stLongitude - computedOptions.stWest) * computedOptions.lonScalar;
        st.y = (stLatitude - computedOptions.stSouth) * computedOptions.latScalar;
      } else {
        st.x = (stLongitude - rectangle.west) * computedOptions.lonScalar;
        st.y = (stLatitude - rectangle.south) * computedOptions.latScalar;
      }
    }
  };

  var rotationMatrixScratch = new Matrix2();
  var nwCartesian = new Cartesian3();
  var centerScratch$2 = new Cartographic();
  var centerCartesian = new Cartesian3();
  var proj = new GeographicProjection();

  function getRotationOptions(
    nwCorner,
    rotation,
    granularityX,
    granularityY,
    center,
    width,
    height
  ) {
    var cosRotation = Math.cos(rotation);
    var granYCos = granularityY * cosRotation;
    var granXCos = granularityX * cosRotation;

    var sinRotation = Math.sin(rotation);
    var granYSin = granularityY * sinRotation;
    var granXSin = granularityX * sinRotation;

    nwCartesian = proj.project(nwCorner, nwCartesian);

    nwCartesian = Cartesian3.subtract(nwCartesian, centerCartesian, nwCartesian);
    var rotationMatrix = Matrix2.fromRotation(rotation, rotationMatrixScratch);
    nwCartesian = Matrix2.multiplyByVector(
      rotationMatrix,
      nwCartesian,
      nwCartesian
    );
    nwCartesian = Cartesian3.add(nwCartesian, centerCartesian, nwCartesian);
    nwCorner = proj.unproject(nwCartesian, nwCorner);

    width -= 1;
    height -= 1;

    var latitude = nwCorner.latitude;
    var latitude0 = latitude + width * granXSin;
    var latitude1 = latitude - granYCos * height;
    var latitude2 = latitude - granYCos * height + width * granXSin;

    var north = Math.max(latitude, latitude0, latitude1, latitude2);
    var south = Math.min(latitude, latitude0, latitude1, latitude2);

    var longitude = nwCorner.longitude;
    var longitude0 = longitude + width * granXCos;
    var longitude1 = longitude + height * granYSin;
    var longitude2 = longitude + height * granYSin + width * granXCos;

    var east = Math.max(longitude, longitude0, longitude1, longitude2);
    var west = Math.min(longitude, longitude0, longitude1, longitude2);

    return {
      north: north,
      south: south,
      east: east,
      west: west,
      granYCos: granYCos,
      granYSin: granYSin,
      granXCos: granXCos,
      granXSin: granXSin,
      nwCorner: nwCorner,
    };
  }

  /**
   * @private
   */
  RectangleGeometryLibrary.computeOptions = function (
    rectangle,
    granularity,
    rotation,
    stRotation,
    boundingRectangleScratch,
    nwCornerResult,
    stNwCornerResult
  ) {
    var east = rectangle.east;
    var west = rectangle.west;
    var north = rectangle.north;
    var south = rectangle.south;

    var northCap = false;
    var southCap = false;

    if (north === CesiumMath.PI_OVER_TWO) {
      northCap = true;
    }
    if (south === -CesiumMath.PI_OVER_TWO) {
      southCap = true;
    }

    var width;
    var height;
    var granularityX;
    var granularityY;
    var dx;
    var dy = north - south;
    if (west > east) {
      dx = CesiumMath.TWO_PI - west + east;
    } else {
      dx = east - west;
    }

    width = Math.ceil(dx / granularity) + 1;
    height = Math.ceil(dy / granularity) + 1;
    granularityX = dx / (width - 1);
    granularityY = dy / (height - 1);

    var nwCorner = Rectangle.northwest(rectangle, nwCornerResult);
    var center = Rectangle.center(rectangle, centerScratch$2);
    if (rotation !== 0 || stRotation !== 0) {
      if (center.longitude < nwCorner.longitude) {
        center.longitude += CesiumMath.TWO_PI;
      }
      centerCartesian = proj.project(center, centerCartesian);
    }

    var granYCos = granularityY;
    var granXCos = granularityX;
    var granYSin = 0.0;
    var granXSin = 0.0;

    var boundingRectangle = Rectangle.clone(rectangle, boundingRectangleScratch);

    var computedOptions = {
      granYCos: granYCos,
      granYSin: granYSin,
      granXCos: granXCos,
      granXSin: granXSin,
      nwCorner: nwCorner,
      boundingRectangle: boundingRectangle,
      width: width,
      height: height,
      northCap: northCap,
      southCap: southCap,
    };

    if (rotation !== 0) {
      var rotationOptions = getRotationOptions(
        nwCorner,
        rotation,
        granularityX,
        granularityY,
        center,
        width,
        height
      );
      north = rotationOptions.north;
      south = rotationOptions.south;
      east = rotationOptions.east;
      west = rotationOptions.west;

      //>>includeStart('debug', pragmas.debug);
      if (
        north < -CesiumMath.PI_OVER_TWO ||
        north > CesiumMath.PI_OVER_TWO ||
        south < -CesiumMath.PI_OVER_TWO ||
        south > CesiumMath.PI_OVER_TWO
      ) {
        throw new DeveloperError(
          "Rotated rectangle is invalid.  It crosses over either the north or south pole."
        );
      }
      //>>includeEnd('debug')

      computedOptions.granYCos = rotationOptions.granYCos;
      computedOptions.granYSin = rotationOptions.granYSin;
      computedOptions.granXCos = rotationOptions.granXCos;
      computedOptions.granXSin = rotationOptions.granXSin;

      boundingRectangle.north = north;
      boundingRectangle.south = south;
      boundingRectangle.east = east;
      boundingRectangle.west = west;
    }

    if (stRotation !== 0) {
      rotation = rotation - stRotation;
      var stNwCorner = Rectangle.northwest(boundingRectangle, stNwCornerResult);

      var stRotationOptions = getRotationOptions(
        stNwCorner,
        rotation,
        granularityX,
        granularityY,
        center,
        width,
        height
      );

      computedOptions.stGranYCos = stRotationOptions.granYCos;
      computedOptions.stGranXCos = stRotationOptions.granXCos;
      computedOptions.stGranYSin = stRotationOptions.granYSin;
      computedOptions.stGranXSin = stRotationOptions.granXSin;
      computedOptions.stNwCorner = stNwCorner;
      computedOptions.stWest = stRotationOptions.west;
      computedOptions.stSouth = stRotationOptions.south;
    }

    return computedOptions;
  };

  var positionScratch$2 = new Cartesian3();
  var normalScratch$3 = new Cartesian3();
  var tangentScratch$1 = new Cartesian3();
  var bitangentScratch$1 = new Cartesian3();
  var rectangleScratch$2 = new Rectangle();
  var stScratch$1 = new Cartesian2();
  var bottomBoundingSphere$2 = new BoundingSphere();
  var topBoundingSphere$2 = new BoundingSphere();

  function createAttributes(vertexFormat, attributes) {
    var geo = new Geometry({
      attributes: new GeometryAttributes(),
      primitiveType: PrimitiveType$1.TRIANGLES,
    });

    geo.attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: attributes.positions,
    });
    if (vertexFormat.normal) {
      geo.attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: attributes.normals,
      });
    }
    if (vertexFormat.tangent) {
      geo.attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: attributes.tangents,
      });
    }
    if (vertexFormat.bitangent) {
      geo.attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: attributes.bitangents,
      });
    }
    return geo;
  }

  function calculateAttributes(
    positions,
    vertexFormat,
    ellipsoid,
    tangentRotationMatrix
  ) {
    var length = positions.length;

    var normals = vertexFormat.normal ? new Float32Array(length) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(length) : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(length)
      : undefined;

    var attrIndex = 0;
    var bitangent = bitangentScratch$1;
    var tangent = tangentScratch$1;
    var normal = normalScratch$3;
    if (vertexFormat.normal || vertexFormat.tangent || vertexFormat.bitangent) {
      for (var i = 0; i < length; i += 3) {
        var p = Cartesian3.fromArray(positions, i, positionScratch$2);
        var attrIndex1 = attrIndex + 1;
        var attrIndex2 = attrIndex + 2;

        normal = ellipsoid.geodeticSurfaceNormal(p, normal);
        if (vertexFormat.tangent || vertexFormat.bitangent) {
          Cartesian3.cross(Cartesian3.UNIT_Z, normal, tangent);
          Matrix3.multiplyByVector(tangentRotationMatrix, tangent, tangent);
          Cartesian3.normalize(tangent, tangent);

          if (vertexFormat.bitangent) {
            Cartesian3.normalize(
              Cartesian3.cross(normal, tangent, bitangent),
              bitangent
            );
          }
        }

        if (vertexFormat.normal) {
          normals[attrIndex] = normal.x;
          normals[attrIndex1] = normal.y;
          normals[attrIndex2] = normal.z;
        }
        if (vertexFormat.tangent) {
          tangents[attrIndex] = tangent.x;
          tangents[attrIndex1] = tangent.y;
          tangents[attrIndex2] = tangent.z;
        }
        if (vertexFormat.bitangent) {
          bitangents[attrIndex] = bitangent.x;
          bitangents[attrIndex1] = bitangent.y;
          bitangents[attrIndex2] = bitangent.z;
        }
        attrIndex += 3;
      }
    }
    return createAttributes(vertexFormat, {
      positions: positions,
      normals: normals,
      tangents: tangents,
      bitangents: bitangents,
    });
  }

  var v1Scratch = new Cartesian3();
  var v2Scratch = new Cartesian3();

  function calculateAttributesWall(positions, vertexFormat, ellipsoid) {
    var length = positions.length;

    var normals = vertexFormat.normal ? new Float32Array(length) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(length) : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(length)
      : undefined;

    var normalIndex = 0;
    var tangentIndex = 0;
    var bitangentIndex = 0;
    var recomputeNormal = true;

    var bitangent = bitangentScratch$1;
    var tangent = tangentScratch$1;
    var normal = normalScratch$3;
    if (vertexFormat.normal || vertexFormat.tangent || vertexFormat.bitangent) {
      for (var i = 0; i < length; i += 6) {
        var p = Cartesian3.fromArray(positions, i, positionScratch$2);
        var p1 = Cartesian3.fromArray(positions, (i + 6) % length, v1Scratch);
        if (recomputeNormal) {
          var p2 = Cartesian3.fromArray(positions, (i + 3) % length, v2Scratch);
          Cartesian3.subtract(p1, p, p1);
          Cartesian3.subtract(p2, p, p2);
          normal = Cartesian3.normalize(Cartesian3.cross(p2, p1, normal), normal);
          recomputeNormal = false;
        }

        if (Cartesian3.equalsEpsilon(p1, p, CesiumMath.EPSILON10)) {
          // if we've reached a corner
          recomputeNormal = true;
        }

        if (vertexFormat.tangent || vertexFormat.bitangent) {
          bitangent = ellipsoid.geodeticSurfaceNormal(p, bitangent);
          if (vertexFormat.tangent) {
            tangent = Cartesian3.normalize(
              Cartesian3.cross(bitangent, normal, tangent),
              tangent
            );
          }
        }

        if (vertexFormat.normal) {
          normals[normalIndex++] = normal.x;
          normals[normalIndex++] = normal.y;
          normals[normalIndex++] = normal.z;
          normals[normalIndex++] = normal.x;
          normals[normalIndex++] = normal.y;
          normals[normalIndex++] = normal.z;
        }

        if (vertexFormat.tangent) {
          tangents[tangentIndex++] = tangent.x;
          tangents[tangentIndex++] = tangent.y;
          tangents[tangentIndex++] = tangent.z;
          tangents[tangentIndex++] = tangent.x;
          tangents[tangentIndex++] = tangent.y;
          tangents[tangentIndex++] = tangent.z;
        }

        if (vertexFormat.bitangent) {
          bitangents[bitangentIndex++] = bitangent.x;
          bitangents[bitangentIndex++] = bitangent.y;
          bitangents[bitangentIndex++] = bitangent.z;
          bitangents[bitangentIndex++] = bitangent.x;
          bitangents[bitangentIndex++] = bitangent.y;
          bitangents[bitangentIndex++] = bitangent.z;
        }
      }
    }

    return createAttributes(vertexFormat, {
      positions: positions,
      normals: normals,
      tangents: tangents,
      bitangents: bitangents,
    });
  }

  function constructRectangle(rectangleGeometry, computedOptions) {
    var vertexFormat = rectangleGeometry._vertexFormat;
    var ellipsoid = rectangleGeometry._ellipsoid;
    var height = computedOptions.height;
    var width = computedOptions.width;
    var northCap = computedOptions.northCap;
    var southCap = computedOptions.southCap;

    var rowStart = 0;
    var rowEnd = height;
    var rowHeight = height;
    var size = 0;
    if (northCap) {
      rowStart = 1;
      rowHeight -= 1;
      size += 1;
    }
    if (southCap) {
      rowEnd -= 1;
      rowHeight -= 1;
      size += 1;
    }
    size += width * rowHeight;

    var positions = vertexFormat.position
      ? new Float64Array(size * 3)
      : undefined;
    var textureCoordinates = vertexFormat.st
      ? new Float32Array(size * 2)
      : undefined;

    var posIndex = 0;
    var stIndex = 0;

    var position = positionScratch$2;
    var st = stScratch$1;

    var minX = Number.MAX_VALUE;
    var minY = Number.MAX_VALUE;
    var maxX = -Number.MAX_VALUE;
    var maxY = -Number.MAX_VALUE;

    for (var row = rowStart; row < rowEnd; ++row) {
      for (var col = 0; col < width; ++col) {
        RectangleGeometryLibrary.computePosition(
          computedOptions,
          ellipsoid,
          vertexFormat.st,
          row,
          col,
          position,
          st
        );

        positions[posIndex++] = position.x;
        positions[posIndex++] = position.y;
        positions[posIndex++] = position.z;

        if (vertexFormat.st) {
          textureCoordinates[stIndex++] = st.x;
          textureCoordinates[stIndex++] = st.y;

          minX = Math.min(minX, st.x);
          minY = Math.min(minY, st.y);
          maxX = Math.max(maxX, st.x);
          maxY = Math.max(maxY, st.y);
        }
      }
    }
    if (northCap) {
      RectangleGeometryLibrary.computePosition(
        computedOptions,
        ellipsoid,
        vertexFormat.st,
        0,
        0,
        position,
        st
      );

      positions[posIndex++] = position.x;
      positions[posIndex++] = position.y;
      positions[posIndex++] = position.z;

      if (vertexFormat.st) {
        textureCoordinates[stIndex++] = st.x;
        textureCoordinates[stIndex++] = st.y;

        minX = st.x;
        minY = st.y;
        maxX = st.x;
        maxY = st.y;
      }
    }
    if (southCap) {
      RectangleGeometryLibrary.computePosition(
        computedOptions,
        ellipsoid,
        vertexFormat.st,
        height - 1,
        0,
        position,
        st
      );

      positions[posIndex++] = position.x;
      positions[posIndex++] = position.y;
      positions[posIndex] = position.z;

      if (vertexFormat.st) {
        textureCoordinates[stIndex++] = st.x;
        textureCoordinates[stIndex] = st.y;

        minX = Math.min(minX, st.x);
        minY = Math.min(minY, st.y);
        maxX = Math.max(maxX, st.x);
        maxY = Math.max(maxY, st.y);
      }
    }

    if (
      vertexFormat.st &&
      (minX < 0.0 || minY < 0.0 || maxX > 1.0 || maxY > 1.0)
    ) {
      for (var k = 0; k < textureCoordinates.length; k += 2) {
        textureCoordinates[k] = (textureCoordinates[k] - minX) / (maxX - minX);
        textureCoordinates[k + 1] =
          (textureCoordinates[k + 1] - minY) / (maxY - minY);
      }
    }

    var geo = calculateAttributes(
      positions,
      vertexFormat,
      ellipsoid,
      computedOptions.tangentRotationMatrix
    );

    var indicesSize = 6 * (width - 1) * (rowHeight - 1);
    if (northCap) {
      indicesSize += 3 * (width - 1);
    }
    if (southCap) {
      indicesSize += 3 * (width - 1);
    }
    var indices = IndexDatatype$1.createTypedArray(size, indicesSize);
    var index = 0;
    var indicesIndex = 0;
    var i;
    for (i = 0; i < rowHeight - 1; ++i) {
      for (var j = 0; j < width - 1; ++j) {
        var upperLeft = index;
        var lowerLeft = upperLeft + width;
        var lowerRight = lowerLeft + 1;
        var upperRight = upperLeft + 1;
        indices[indicesIndex++] = upperLeft;
        indices[indicesIndex++] = lowerLeft;
        indices[indicesIndex++] = upperRight;
        indices[indicesIndex++] = upperRight;
        indices[indicesIndex++] = lowerLeft;
        indices[indicesIndex++] = lowerRight;
        ++index;
      }
      ++index;
    }
    if (northCap || southCap) {
      var northIndex = size - 1;
      var southIndex = size - 1;
      if (northCap && southCap) {
        northIndex = size - 2;
      }

      var p1;
      var p2;
      index = 0;

      if (northCap) {
        for (i = 0; i < width - 1; i++) {
          p1 = index;
          p2 = p1 + 1;
          indices[indicesIndex++] = northIndex;
          indices[indicesIndex++] = p1;
          indices[indicesIndex++] = p2;
          ++index;
        }
      }
      if (southCap) {
        index = (rowHeight - 1) * width;
        for (i = 0; i < width - 1; i++) {
          p1 = index;
          p2 = p1 + 1;
          indices[indicesIndex++] = p1;
          indices[indicesIndex++] = southIndex;
          indices[indicesIndex++] = p2;
          ++index;
        }
      }
    }

    geo.indices = indices;
    if (vertexFormat.st) {
      geo.attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: textureCoordinates,
      });
    }

    return geo;
  }

  function addWallPositions$1(
    wallPositions,
    posIndex,
    i,
    topPositions,
    bottomPositions
  ) {
    wallPositions[posIndex++] = topPositions[i];
    wallPositions[posIndex++] = topPositions[i + 1];
    wallPositions[posIndex++] = topPositions[i + 2];
    wallPositions[posIndex++] = bottomPositions[i];
    wallPositions[posIndex++] = bottomPositions[i + 1];
    wallPositions[posIndex] = bottomPositions[i + 2];
    return wallPositions;
  }

  function addWallTextureCoordinates(wallTextures, stIndex, i, st) {
    wallTextures[stIndex++] = st[i];
    wallTextures[stIndex++] = st[i + 1];
    wallTextures[stIndex++] = st[i];
    wallTextures[stIndex] = st[i + 1];
    return wallTextures;
  }

  var scratchVertexFormat$b = new VertexFormat();

  function constructExtrudedRectangle(rectangleGeometry, computedOptions) {
    var shadowVolume = rectangleGeometry._shadowVolume;
    var offsetAttributeValue = rectangleGeometry._offsetAttribute;
    var vertexFormat = rectangleGeometry._vertexFormat;
    var minHeight = rectangleGeometry._extrudedHeight;
    var maxHeight = rectangleGeometry._surfaceHeight;
    var ellipsoid = rectangleGeometry._ellipsoid;

    var height = computedOptions.height;
    var width = computedOptions.width;

    var i;

    if (shadowVolume) {
      var newVertexFormat = VertexFormat.clone(vertexFormat, scratchVertexFormat$b);
      newVertexFormat.normal = true;
      rectangleGeometry._vertexFormat = newVertexFormat;
    }

    var topBottomGeo = constructRectangle(rectangleGeometry, computedOptions);

    if (shadowVolume) {
      rectangleGeometry._vertexFormat = vertexFormat;
    }

    var topPositions = PolygonPipeline.scaleToGeodeticHeight(
      topBottomGeo.attributes.position.values,
      maxHeight,
      ellipsoid,
      false
    );
    topPositions = new Float64Array(topPositions);
    var length = topPositions.length;
    var newLength = length * 2;
    var positions = new Float64Array(newLength);
    positions.set(topPositions);
    var bottomPositions = PolygonPipeline.scaleToGeodeticHeight(
      topBottomGeo.attributes.position.values,
      minHeight,
      ellipsoid
    );
    positions.set(bottomPositions, length);
    topBottomGeo.attributes.position.values = positions;

    var normals = vertexFormat.normal ? new Float32Array(newLength) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(newLength) : undefined;
    var bitangents = vertexFormat.bitangent
      ? new Float32Array(newLength)
      : undefined;
    var textures = vertexFormat.st
      ? new Float32Array((newLength / 3) * 2)
      : undefined;
    var topSt;
    var topNormals;
    if (vertexFormat.normal) {
      topNormals = topBottomGeo.attributes.normal.values;
      normals.set(topNormals);
      for (i = 0; i < length; i++) {
        topNormals[i] = -topNormals[i];
      }
      normals.set(topNormals, length);
      topBottomGeo.attributes.normal.values = normals;
    }
    if (shadowVolume) {
      topNormals = topBottomGeo.attributes.normal.values;
      if (!vertexFormat.normal) {
        topBottomGeo.attributes.normal = undefined;
      }
      var extrudeNormals = new Float32Array(newLength);
      for (i = 0; i < length; i++) {
        topNormals[i] = -topNormals[i];
      }
      extrudeNormals.set(topNormals, length); //only get normals for bottom layer that's going to be pushed down
      topBottomGeo.attributes.extrudeDirection = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: extrudeNormals,
      });
    }

    var offsetValue;
    var hasOffsets = defined(offsetAttributeValue);
    if (hasOffsets) {
      var size = (length / 3) * 2;
      var offsetAttribute = new Uint8Array(size);
      if (offsetAttributeValue === GeometryOffsetAttribute$1.TOP) {
        offsetAttribute = arrayFill(offsetAttribute, 1, 0, size / 2);
      } else {
        offsetValue =
          offsetAttributeValue === GeometryOffsetAttribute$1.NONE ? 0 : 1;
        offsetAttribute = arrayFill(offsetAttribute, offsetValue);
      }

      topBottomGeo.attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: offsetAttribute,
      });
    }

    if (vertexFormat.tangent) {
      var topTangents = topBottomGeo.attributes.tangent.values;
      tangents.set(topTangents);
      for (i = 0; i < length; i++) {
        topTangents[i] = -topTangents[i];
      }
      tangents.set(topTangents, length);
      topBottomGeo.attributes.tangent.values = tangents;
    }
    if (vertexFormat.bitangent) {
      var topBitangents = topBottomGeo.attributes.bitangent.values;
      bitangents.set(topBitangents);
      bitangents.set(topBitangents, length);
      topBottomGeo.attributes.bitangent.values = bitangents;
    }
    if (vertexFormat.st) {
      topSt = topBottomGeo.attributes.st.values;
      textures.set(topSt);
      textures.set(topSt, (length / 3) * 2);
      topBottomGeo.attributes.st.values = textures;
    }

    var indices = topBottomGeo.indices;
    var indicesLength = indices.length;
    var posLength = length / 3;
    var newIndices = IndexDatatype$1.createTypedArray(
      newLength / 3,
      indicesLength * 2
    );
    newIndices.set(indices);
    for (i = 0; i < indicesLength; i += 3) {
      newIndices[i + indicesLength] = indices[i + 2] + posLength;
      newIndices[i + 1 + indicesLength] = indices[i + 1] + posLength;
      newIndices[i + 2 + indicesLength] = indices[i] + posLength;
    }
    topBottomGeo.indices = newIndices;

    var northCap = computedOptions.northCap;
    var southCap = computedOptions.southCap;

    var rowHeight = height;
    var widthMultiplier = 2;
    var perimeterPositions = 0;
    var corners = 4;
    var dupliateCorners = 4;
    if (northCap) {
      widthMultiplier -= 1;
      rowHeight -= 1;
      perimeterPositions += 1;
      corners -= 2;
      dupliateCorners -= 1;
    }
    if (southCap) {
      widthMultiplier -= 1;
      rowHeight -= 1;
      perimeterPositions += 1;
      corners -= 2;
      dupliateCorners -= 1;
    }
    perimeterPositions += widthMultiplier * width + 2 * rowHeight - corners;

    var wallCount = (perimeterPositions + dupliateCorners) * 2;

    var wallPositions = new Float64Array(wallCount * 3);
    var wallExtrudeNormals = shadowVolume
      ? new Float32Array(wallCount * 3)
      : undefined;
    var wallOffsetAttribute = hasOffsets ? new Uint8Array(wallCount) : undefined;
    var wallTextures = vertexFormat.st
      ? new Float32Array(wallCount * 2)
      : undefined;

    var computeTopOffsets = offsetAttributeValue === GeometryOffsetAttribute$1.TOP;
    if (hasOffsets && !computeTopOffsets) {
      offsetValue = offsetAttributeValue === GeometryOffsetAttribute$1.ALL ? 1 : 0;
      wallOffsetAttribute = arrayFill(wallOffsetAttribute, offsetValue);
    }

    var posIndex = 0;
    var stIndex = 0;
    var extrudeNormalIndex = 0;
    var wallOffsetIndex = 0;
    var area = width * rowHeight;
    var threeI;
    for (i = 0; i < area; i += width) {
      threeI = i * 3;
      wallPositions = addWallPositions$1(
        wallPositions,
        posIndex,
        threeI,
        topPositions,
        bottomPositions
      );
      posIndex += 6;
      if (vertexFormat.st) {
        wallTextures = addWallTextureCoordinates(
          wallTextures,
          stIndex,
          i * 2,
          topSt
        );
        stIndex += 4;
      }
      if (shadowVolume) {
        extrudeNormalIndex += 3;
        wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI];
        wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 1];
        wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 2];
      }
      if (computeTopOffsets) {
        wallOffsetAttribute[wallOffsetIndex++] = 1;
        wallOffsetIndex += 1;
      }
    }

    if (!southCap) {
      for (i = area - width; i < area; i++) {
        threeI = i * 3;
        wallPositions = addWallPositions$1(
          wallPositions,
          posIndex,
          threeI,
          topPositions,
          bottomPositions
        );
        posIndex += 6;
        if (vertexFormat.st) {
          wallTextures = addWallTextureCoordinates(
            wallTextures,
            stIndex,
            i * 2,
            topSt
          );
          stIndex += 4;
        }
        if (shadowVolume) {
          extrudeNormalIndex += 3;
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 1];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 2];
        }
        if (computeTopOffsets) {
          wallOffsetAttribute[wallOffsetIndex++] = 1;
          wallOffsetIndex += 1;
        }
      }
    } else {
      var southIndex = northCap ? area + 1 : area;
      threeI = southIndex * 3;

      for (i = 0; i < 2; i++) {
        // duplicate corner points
        wallPositions = addWallPositions$1(
          wallPositions,
          posIndex,
          threeI,
          topPositions,
          bottomPositions
        );
        posIndex += 6;
        if (vertexFormat.st) {
          wallTextures = addWallTextureCoordinates(
            wallTextures,
            stIndex,
            southIndex * 2,
            topSt
          );
          stIndex += 4;
        }
        if (shadowVolume) {
          extrudeNormalIndex += 3;
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 1];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 2];
        }
        if (computeTopOffsets) {
          wallOffsetAttribute[wallOffsetIndex++] = 1;
          wallOffsetIndex += 1;
        }
      }
    }

    for (i = area - 1; i > 0; i -= width) {
      threeI = i * 3;
      wallPositions = addWallPositions$1(
        wallPositions,
        posIndex,
        threeI,
        topPositions,
        bottomPositions
      );
      posIndex += 6;
      if (vertexFormat.st) {
        wallTextures = addWallTextureCoordinates(
          wallTextures,
          stIndex,
          i * 2,
          topSt
        );
        stIndex += 4;
      }
      if (shadowVolume) {
        extrudeNormalIndex += 3;
        wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI];
        wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 1];
        wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 2];
      }
      if (computeTopOffsets) {
        wallOffsetAttribute[wallOffsetIndex++] = 1;
        wallOffsetIndex += 1;
      }
    }

    if (!northCap) {
      for (i = width - 1; i >= 0; i--) {
        threeI = i * 3;
        wallPositions = addWallPositions$1(
          wallPositions,
          posIndex,
          threeI,
          topPositions,
          bottomPositions
        );
        posIndex += 6;
        if (vertexFormat.st) {
          wallTextures = addWallTextureCoordinates(
            wallTextures,
            stIndex,
            i * 2,
            topSt
          );
          stIndex += 4;
        }
        if (shadowVolume) {
          extrudeNormalIndex += 3;
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 1];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 2];
        }
        if (computeTopOffsets) {
          wallOffsetAttribute[wallOffsetIndex++] = 1;
          wallOffsetIndex += 1;
        }
      }
    } else {
      var northIndex = area;
      threeI = northIndex * 3;

      for (i = 0; i < 2; i++) {
        // duplicate corner points
        wallPositions = addWallPositions$1(
          wallPositions,
          posIndex,
          threeI,
          topPositions,
          bottomPositions
        );
        posIndex += 6;
        if (vertexFormat.st) {
          wallTextures = addWallTextureCoordinates(
            wallTextures,
            stIndex,
            northIndex * 2,
            topSt
          );
          stIndex += 4;
        }
        if (shadowVolume) {
          extrudeNormalIndex += 3;
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 1];
          wallExtrudeNormals[extrudeNormalIndex++] = topNormals[threeI + 2];
        }
        if (computeTopOffsets) {
          wallOffsetAttribute[wallOffsetIndex++] = 1;
          wallOffsetIndex += 1;
        }
      }
    }

    var geo = calculateAttributesWall(wallPositions, vertexFormat, ellipsoid);

    if (vertexFormat.st) {
      geo.attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: wallTextures,
      });
    }
    if (shadowVolume) {
      geo.attributes.extrudeDirection = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: wallExtrudeNormals,
      });
    }
    if (hasOffsets) {
      geo.attributes.applyOffset = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 1,
        values: wallOffsetAttribute,
      });
    }

    var wallIndices = IndexDatatype$1.createTypedArray(
      wallCount,
      perimeterPositions * 6
    );

    var upperLeft;
    var lowerLeft;
    var lowerRight;
    var upperRight;
    length = wallPositions.length / 3;
    var index = 0;
    for (i = 0; i < length - 1; i += 2) {
      upperLeft = i;
      upperRight = (upperLeft + 2) % length;
      var p1 = Cartesian3.fromArray(wallPositions, upperLeft * 3, v1Scratch);
      var p2 = Cartesian3.fromArray(wallPositions, upperRight * 3, v2Scratch);
      if (Cartesian3.equalsEpsilon(p1, p2, CesiumMath.EPSILON10)) {
        continue;
      }
      lowerLeft = (upperLeft + 1) % length;
      lowerRight = (lowerLeft + 2) % length;
      wallIndices[index++] = upperLeft;
      wallIndices[index++] = lowerLeft;
      wallIndices[index++] = upperRight;
      wallIndices[index++] = upperRight;
      wallIndices[index++] = lowerLeft;
      wallIndices[index++] = lowerRight;
    }

    geo.indices = wallIndices;

    geo = GeometryPipeline.combineInstances([
      new GeometryInstance({
        geometry: topBottomGeo,
      }),
      new GeometryInstance({
        geometry: geo,
      }),
    ]);

    return geo[0];
  }

  var scratchRectanglePoints = [
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
  ];
  var nwScratch = new Cartographic();
  var stNwScratch = new Cartographic();
  function computeRectangle$3(rectangle, granularity, rotation, ellipsoid, result) {
    if (rotation === 0.0) {
      return Rectangle.clone(rectangle, result);
    }

    var computedOptions = RectangleGeometryLibrary.computeOptions(
      rectangle,
      granularity,
      rotation,
      0,
      rectangleScratch$2,
      nwScratch
    );

    var height = computedOptions.height;
    var width = computedOptions.width;

    var positions = scratchRectanglePoints;
    RectangleGeometryLibrary.computePosition(
      computedOptions,
      ellipsoid,
      false,
      0,
      0,
      positions[0]
    );
    RectangleGeometryLibrary.computePosition(
      computedOptions,
      ellipsoid,
      false,
      0,
      width - 1,
      positions[1]
    );
    RectangleGeometryLibrary.computePosition(
      computedOptions,
      ellipsoid,
      false,
      height - 1,
      0,
      positions[2]
    );
    RectangleGeometryLibrary.computePosition(
      computedOptions,
      ellipsoid,
      false,
      height - 1,
      width - 1,
      positions[3]
    );

    return Rectangle.fromCartesianArray(positions, ellipsoid, result);
  }

  /**
   * A description of a cartographic rectangle on an ellipsoid centered at the origin. Rectangle geometry can be rendered with both {@link Primitive} and {@link GroundPrimitive}.
   *
   * @alias RectangleGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Rectangle} options.rectangle A cartographic rectangle with north, south, east and west properties in radians.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the rectangle lies.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number} [options.height=0.0] The distance in meters between the rectangle and the ellipsoid surface.
   * @param {Number} [options.rotation=0.0] The rotation of the rectangle, in radians. A positive rotation is counter-clockwise.
   * @param {Number} [options.stRotation=0.0] The rotation of the texture coordinates, in radians. A positive rotation is counter-clockwise.
   * @param {Number} [options.extrudedHeight] The distance in meters between the rectangle's extruded face and the ellipsoid surface.
   *
   * @exception {DeveloperError} <code>options.rectangle.north</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
   * @exception {DeveloperError} <code>options.rectangle.south</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
   * @exception {DeveloperError} <code>options.rectangle.east</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
   * @exception {DeveloperError} <code>options.rectangle.west</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
   * @exception {DeveloperError} <code>options.rectangle.north</code> must be greater than <code>options.rectangle.south</code>.
   *
   * @see RectangleGeometry#createGeometry
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Rectangle.html|Cesium Sandcastle Rectangle Demo}
   *
   * @example
   * // 1. create a rectangle
   * var rectangle = new Cesium.RectangleGeometry({
   *   ellipsoid : Cesium.Ellipsoid.WGS84,
   *   rectangle : Cesium.Rectangle.fromDegrees(-80.0, 39.0, -74.0, 42.0),
   *   height : 10000.0
   * });
   * var geometry = Cesium.RectangleGeometry.createGeometry(rectangle);
   *
   * // 2. create an extruded rectangle without a top
   * var rectangle = new Cesium.RectangleGeometry({
   *   ellipsoid : Cesium.Ellipsoid.WGS84,
   *   rectangle : Cesium.Rectangle.fromDegrees(-80.0, 39.0, -74.0, 42.0),
   *   height : 10000.0,
   *   extrudedHeight: 300000
   * });
   * var geometry = Cesium.RectangleGeometry.createGeometry(rectangle);
   */
  function RectangleGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var rectangle = options.rectangle;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Rectangle.validate(rectangle);
    if (rectangle.north < rectangle.south) {
      throw new DeveloperError(
        "options.rectangle.north must be greater than or equal to options.rectangle.south"
      );
    }
    //>>includeEnd('debug');

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    this._rectangle = Rectangle.clone(rectangle);
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._ellipsoid = Ellipsoid.clone(
      defaultValue(options.ellipsoid, Ellipsoid.WGS84)
    );
    this._surfaceHeight = Math.max(height, extrudedHeight);
    this._rotation = defaultValue(options.rotation, 0.0);
    this._stRotation = defaultValue(options.stRotation, 0.0);
    this._vertexFormat = VertexFormat.clone(
      defaultValue(options.vertexFormat, VertexFormat.DEFAULT)
    );
    this._extrudedHeight = Math.min(height, extrudedHeight);
    this._shadowVolume = defaultValue(options.shadowVolume, false);
    this._workerName = "createRectangleGeometry";
    this._offsetAttribute = options.offsetAttribute;
    this._rotatedRectangle = undefined;

    this._textureCoordinateRotationPoints = undefined;
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  RectangleGeometry.packedLength =
    Rectangle.packedLength +
    Ellipsoid.packedLength +
    VertexFormat.packedLength +
    7;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {RectangleGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  RectangleGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Rectangle.pack(value._rectangle, array, startingIndex);
    startingIndex += Rectangle.packedLength;

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._surfaceHeight;
    array[startingIndex++] = value._rotation;
    array[startingIndex++] = value._stRotation;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex++] = value._shadowVolume ? 1.0 : 0.0;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchRectangle = new Rectangle();
  var scratchEllipsoid$a = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchOptions$i = {
    rectangle: scratchRectangle,
    ellipsoid: scratchEllipsoid$a,
    vertexFormat: scratchVertexFormat$b,
    granularity: undefined,
    height: undefined,
    rotation: undefined,
    stRotation: undefined,
    extrudedHeight: undefined,
    shadowVolume: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {RectangleGeometry} [result] The object into which to store the result.
   * @returns {RectangleGeometry} The modified result parameter or a new RectangleGeometry instance if one was not provided.
   */
  RectangleGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var rectangle = Rectangle.unpack(array, startingIndex, scratchRectangle);
    startingIndex += Rectangle.packedLength;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$a);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$b
    );
    startingIndex += VertexFormat.packedLength;

    var granularity = array[startingIndex++];
    var surfaceHeight = array[startingIndex++];
    var rotation = array[startingIndex++];
    var stRotation = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var shadowVolume = array[startingIndex++] === 1.0;
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$i.granularity = granularity;
      scratchOptions$i.height = surfaceHeight;
      scratchOptions$i.rotation = rotation;
      scratchOptions$i.stRotation = stRotation;
      scratchOptions$i.extrudedHeight = extrudedHeight;
      scratchOptions$i.shadowVolume = shadowVolume;
      scratchOptions$i.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;

      return new RectangleGeometry(scratchOptions$i);
    }

    result._rectangle = Rectangle.clone(rectangle, result._rectangle);
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._granularity = granularity;
    result._surfaceHeight = surfaceHeight;
    result._rotation = rotation;
    result._stRotation = stRotation;
    result._extrudedHeight = extrudedHeight;
    result._shadowVolume = shadowVolume;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  /**
   * Computes the bounding rectangle based on the provided options
   *
   * @param {Object} options Object with the following properties:
   * @param {Rectangle} options.rectangle A cartographic rectangle with north, south, east and west properties in radians.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the rectangle lies.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number} [options.rotation=0.0] The rotation of the rectangle, in radians. A positive rotation is counter-clockwise.
   * @param {Rectangle} [result] An object in which to store the result.
   *
   * @returns {Rectangle} The result rectangle
   */
  RectangleGeometry.computeRectangle = function (options, result) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var rectangle = options.rectangle;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    Rectangle.validate(rectangle);
    if (rectangle.north < rectangle.south) {
      throw new DeveloperError(
        "options.rectangle.north must be greater than or equal to options.rectangle.south"
      );
    }
    //>>includeEnd('debug');

    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var rotation = defaultValue(options.rotation, 0.0);

    return computeRectangle$3(rectangle, granularity, rotation, ellipsoid, result);
  };

  var tangentRotationMatrixScratch = new Matrix3();
  var quaternionScratch$3 = new Quaternion();
  var centerScratch$3 = new Cartographic();
  /**
   * Computes the geometric representation of a rectangle, including its vertices, indices, and a bounding sphere.
   *
   * @param {RectangleGeometry} rectangleGeometry A description of the rectangle.
   * @returns {Geometry|undefined} The computed vertices and indices.
   *
   * @exception {DeveloperError} Rotated rectangle is invalid.
   */
  RectangleGeometry.createGeometry = function (rectangleGeometry) {
    if (
      CesiumMath.equalsEpsilon(
        rectangleGeometry._rectangle.north,
        rectangleGeometry._rectangle.south,
        CesiumMath.EPSILON10
      ) ||
      CesiumMath.equalsEpsilon(
        rectangleGeometry._rectangle.east,
        rectangleGeometry._rectangle.west,
        CesiumMath.EPSILON10
      )
    ) {
      return undefined;
    }

    var rectangle = rectangleGeometry._rectangle;
    var ellipsoid = rectangleGeometry._ellipsoid;
    var rotation = rectangleGeometry._rotation;
    var stRotation = rectangleGeometry._stRotation;
    var vertexFormat = rectangleGeometry._vertexFormat;

    var computedOptions = RectangleGeometryLibrary.computeOptions(
      rectangle,
      rectangleGeometry._granularity,
      rotation,
      stRotation,
      rectangleScratch$2,
      nwScratch,
      stNwScratch
    );

    var tangentRotationMatrix = tangentRotationMatrixScratch;
    if (stRotation !== 0 || rotation !== 0) {
      var center = Rectangle.center(rectangle, centerScratch$3);
      var axis = ellipsoid.geodeticSurfaceNormalCartographic(center, v1Scratch);
      Quaternion.fromAxisAngle(axis, -stRotation, quaternionScratch$3);
      Matrix3.fromQuaternion(quaternionScratch$3, tangentRotationMatrix);
    } else {
      Matrix3.clone(Matrix3.IDENTITY, tangentRotationMatrix);
    }

    var surfaceHeight = rectangleGeometry._surfaceHeight;
    var extrudedHeight = rectangleGeometry._extrudedHeight;
    var extrude = !CesiumMath.equalsEpsilon(
      surfaceHeight,
      extrudedHeight,
      0,
      CesiumMath.EPSILON2
    );

    computedOptions.lonScalar = 1.0 / rectangleGeometry._rectangle.width;
    computedOptions.latScalar = 1.0 / rectangleGeometry._rectangle.height;
    computedOptions.tangentRotationMatrix = tangentRotationMatrix;

    var geometry;
    var boundingSphere;
    rectangle = rectangleGeometry._rectangle;
    if (extrude) {
      geometry = constructExtrudedRectangle(rectangleGeometry, computedOptions);
      var topBS = BoundingSphere.fromRectangle3D(
        rectangle,
        ellipsoid,
        surfaceHeight,
        topBoundingSphere$2
      );
      var bottomBS = BoundingSphere.fromRectangle3D(
        rectangle,
        ellipsoid,
        extrudedHeight,
        bottomBoundingSphere$2
      );
      boundingSphere = BoundingSphere.union(topBS, bottomBS);
    } else {
      geometry = constructRectangle(rectangleGeometry, computedOptions);
      geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
        geometry.attributes.position.values,
        surfaceHeight,
        ellipsoid,
        false
      );

      if (defined(rectangleGeometry._offsetAttribute)) {
        var length = geometry.attributes.position.values.length;
        var applyOffset = new Uint8Array(length / 3);
        var offsetValue =
          rectangleGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
            ? 0
            : 1;
        arrayFill(applyOffset, offsetValue);
        geometry.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: applyOffset,
        });
      }

      boundingSphere = BoundingSphere.fromRectangle3D(
        rectangle,
        ellipsoid,
        surfaceHeight
      );
    }

    if (!vertexFormat.position) {
      delete geometry.attributes.position;
    }

    return new Geometry({
      attributes: geometry.attributes,
      indices: geometry.indices,
      primitiveType: geometry.primitiveType,
      boundingSphere: boundingSphere,
      offsetAttribute: rectangleGeometry._offsetAttribute,
    });
  };

  /**
   * @private
   */
  RectangleGeometry.createShadowVolume = function (
    rectangleGeometry,
    minHeightFunc,
    maxHeightFunc
  ) {
    var granularity = rectangleGeometry._granularity;
    var ellipsoid = rectangleGeometry._ellipsoid;

    var minHeight = minHeightFunc(granularity, ellipsoid);
    var maxHeight = maxHeightFunc(granularity, ellipsoid);

    return new RectangleGeometry({
      rectangle: rectangleGeometry._rectangle,
      rotation: rectangleGeometry._rotation,
      ellipsoid: ellipsoid,
      stRotation: rectangleGeometry._stRotation,
      granularity: granularity,
      extrudedHeight: maxHeight,
      height: minHeight,
      vertexFormat: VertexFormat.POSITION_ONLY,
      shadowVolume: true,
    });
  };

  var unrotatedTextureRectangleScratch = new Rectangle();
  var points2DScratch$1 = [new Cartesian2(), new Cartesian2(), new Cartesian2()];
  var rotation2DScratch$1 = new Matrix2();
  var rectangleCenterScratch$1 = new Cartographic();

  function textureCoordinateRotationPoints$2(rectangleGeometry) {
    if (rectangleGeometry._stRotation === 0.0) {
      return [0, 0, 0, 1, 1, 0];
    }

    var rectangle = Rectangle.clone(
      rectangleGeometry._rectangle,
      unrotatedTextureRectangleScratch
    );
    var granularity = rectangleGeometry._granularity;
    var ellipsoid = rectangleGeometry._ellipsoid;

    // Rotate to align the texture coordinates with ENU
    var rotation = rectangleGeometry._rotation - rectangleGeometry._stRotation;

    var unrotatedTextureRectangle = computeRectangle$3(
      rectangle,
      granularity,
      rotation,
      ellipsoid,
      unrotatedTextureRectangleScratch
    );

    // Assume a computed "east-north" texture coordinate system based on spherical or planar tricks, bounded by `boundingRectangle`.
    // The "desired" texture coordinate system forms an oriented rectangle (un-oriented computed) around the geometry that completely and tightly bounds it.
    // We want to map from the "east-north" texture coordinate system into the "desired" system using a pair of lines (analagous planes in 2D)
    // Compute 3 corners of the "desired" texture coordinate system in "east-north" texture space by the following in cartographic space:
    // - rotate 3 of the corners in unrotatedTextureRectangle by stRotation around the center of the bounding rectangle
    // - apply the "east-north" system's normalization formula to the rotated cartographics, even though this is likely to produce values outside [0-1].
    // This gives us a set of points in the "east-north" texture coordinate system that can be used to map "east-north" texture coordinates to "desired."

    var points2D = points2DScratch$1;
    points2D[0].x = unrotatedTextureRectangle.west;
    points2D[0].y = unrotatedTextureRectangle.south;

    points2D[1].x = unrotatedTextureRectangle.west;
    points2D[1].y = unrotatedTextureRectangle.north;

    points2D[2].x = unrotatedTextureRectangle.east;
    points2D[2].y = unrotatedTextureRectangle.south;

    var boundingRectangle = rectangleGeometry.rectangle;
    var toDesiredInComputed = Matrix2.fromRotation(
      rectangleGeometry._stRotation,
      rotation2DScratch$1
    );
    var boundingRectangleCenter = Rectangle.center(
      boundingRectangle,
      rectangleCenterScratch$1
    );

    for (var i = 0; i < 3; ++i) {
      var point2D = points2D[i];
      point2D.x -= boundingRectangleCenter.longitude;
      point2D.y -= boundingRectangleCenter.latitude;
      Matrix2.multiplyByVector(toDesiredInComputed, point2D, point2D);
      point2D.x += boundingRectangleCenter.longitude;
      point2D.y += boundingRectangleCenter.latitude;

      // Convert point into east-north texture coordinate space
      point2D.x = (point2D.x - boundingRectangle.west) / boundingRectangle.width;
      point2D.y =
        (point2D.y - boundingRectangle.south) / boundingRectangle.height;
    }

    var minXYCorner = points2D[0];
    var maxYCorner = points2D[1];
    var maxXCorner = points2D[2];
    var result = new Array(6);
    Cartesian2.pack(minXYCorner, result);
    Cartesian2.pack(maxYCorner, result, 2);
    Cartesian2.pack(maxXCorner, result, 4);
    return result;
  }

  Object.defineProperties(RectangleGeometry.prototype, {
    /**
     * @private
     */
    rectangle: {
      get: function () {
        if (!defined(this._rotatedRectangle)) {
          this._rotatedRectangle = computeRectangle$3(
            this._rectangle,
            this._granularity,
            this._rotation,
            this._ellipsoid
          );
        }
        return this._rotatedRectangle;
      },
    },
    /**
     * For remapping texture coordinates when rendering RectangleGeometries as GroundPrimitives.
     * This version permits skew in textures by computing offsets directly in cartographic space and
     * more accurately approximates rendering RectangleGeometries with height as standard Primitives.
     * @see Geometry#_textureCoordinateRotationPoints
     * @private
     */
    textureCoordinateRotationPoints: {
      get: function () {
        if (!defined(this._textureCoordinateRotationPoints)) {
          this._textureCoordinateRotationPoints = textureCoordinateRotationPoints$2(
            this
          );
        }
        return this._textureCoordinateRotationPoints;
      },
    },
  });

  var bottomBoundingSphere$3 = new BoundingSphere();
  var topBoundingSphere$3 = new BoundingSphere();
  var positionScratch$3 = new Cartesian3();
  var rectangleScratch$3 = new Rectangle();

  function constructRectangle$1(geometry, computedOptions) {
    var ellipsoid = geometry._ellipsoid;
    var height = computedOptions.height;
    var width = computedOptions.width;
    var northCap = computedOptions.northCap;
    var southCap = computedOptions.southCap;

    var rowHeight = height;
    var widthMultiplier = 2;
    var size = 0;
    var corners = 4;
    if (northCap) {
      widthMultiplier -= 1;
      rowHeight -= 1;
      size += 1;
      corners -= 2;
    }
    if (southCap) {
      widthMultiplier -= 1;
      rowHeight -= 1;
      size += 1;
      corners -= 2;
    }
    size += widthMultiplier * width + 2 * rowHeight - corners;

    var positions = new Float64Array(size * 3);

    var posIndex = 0;
    var row = 0;
    var col;
    var position = positionScratch$3;
    if (northCap) {
      RectangleGeometryLibrary.computePosition(
        computedOptions,
        ellipsoid,
        false,
        row,
        0,
        position
      );
      positions[posIndex++] = position.x;
      positions[posIndex++] = position.y;
      positions[posIndex++] = position.z;
    } else {
      for (col = 0; col < width; col++) {
        RectangleGeometryLibrary.computePosition(
          computedOptions,
          ellipsoid,
          false,
          row,
          col,
          position
        );
        positions[posIndex++] = position.x;
        positions[posIndex++] = position.y;
        positions[posIndex++] = position.z;
      }
    }

    col = width - 1;
    for (row = 1; row < height; row++) {
      RectangleGeometryLibrary.computePosition(
        computedOptions,
        ellipsoid,
        false,
        row,
        col,
        position
      );
      positions[posIndex++] = position.x;
      positions[posIndex++] = position.y;
      positions[posIndex++] = position.z;
    }

    row = height - 1;
    if (!southCap) {
      // if southCap is true, we dont need to add any more points because the south pole point was added by the iteration above
      for (col = width - 2; col >= 0; col--) {
        RectangleGeometryLibrary.computePosition(
          computedOptions,
          ellipsoid,
          false,
          row,
          col,
          position
        );
        positions[posIndex++] = position.x;
        positions[posIndex++] = position.y;
        positions[posIndex++] = position.z;
      }
    }

    col = 0;
    for (row = height - 2; row > 0; row--) {
      RectangleGeometryLibrary.computePosition(
        computedOptions,
        ellipsoid,
        false,
        row,
        col,
        position
      );
      positions[posIndex++] = position.x;
      positions[posIndex++] = position.y;
      positions[posIndex++] = position.z;
    }

    var indicesSize = (positions.length / 3) * 2;
    var indices = IndexDatatype$1.createTypedArray(
      positions.length / 3,
      indicesSize
    );

    var index = 0;
    for (var i = 0; i < positions.length / 3 - 1; i++) {
      indices[index++] = i;
      indices[index++] = i + 1;
    }
    indices[index++] = positions.length / 3 - 1;
    indices[index++] = 0;

    var geo = new Geometry({
      attributes: new GeometryAttributes(),
      primitiveType: PrimitiveType$1.LINES,
    });

    geo.attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: positions,
    });
    geo.indices = indices;

    return geo;
  }

  function constructExtrudedRectangle$1(rectangleGeometry, computedOptions) {
    var surfaceHeight = rectangleGeometry._surfaceHeight;
    var extrudedHeight = rectangleGeometry._extrudedHeight;
    var ellipsoid = rectangleGeometry._ellipsoid;
    var minHeight = extrudedHeight;
    var maxHeight = surfaceHeight;
    var geo = constructRectangle$1(rectangleGeometry, computedOptions);

    var height = computedOptions.height;
    var width = computedOptions.width;

    var topPositions = PolygonPipeline.scaleToGeodeticHeight(
      geo.attributes.position.values,
      maxHeight,
      ellipsoid,
      false
    );
    var length = topPositions.length;
    var positions = new Float64Array(length * 2);
    positions.set(topPositions);
    var bottomPositions = PolygonPipeline.scaleToGeodeticHeight(
      geo.attributes.position.values,
      minHeight,
      ellipsoid
    );
    positions.set(bottomPositions, length);
    geo.attributes.position.values = positions;

    var northCap = computedOptions.northCap;
    var southCap = computedOptions.southCap;
    var corners = 4;
    if (northCap) {
      corners -= 1;
    }
    if (southCap) {
      corners -= 1;
    }

    var indicesSize = (positions.length / 3 + corners) * 2;
    var indices = IndexDatatype$1.createTypedArray(
      positions.length / 3,
      indicesSize
    );
    length = positions.length / 6;
    var index = 0;
    for (var i = 0; i < length - 1; i++) {
      indices[index++] = i;
      indices[index++] = i + 1;
      indices[index++] = i + length;
      indices[index++] = i + length + 1;
    }
    indices[index++] = length - 1;
    indices[index++] = 0;
    indices[index++] = length + length - 1;
    indices[index++] = length;

    indices[index++] = 0;
    indices[index++] = length;

    var bottomCorner;
    if (northCap) {
      bottomCorner = height - 1;
    } else {
      var topRightCorner = width - 1;
      indices[index++] = topRightCorner;
      indices[index++] = topRightCorner + length;
      bottomCorner = width + height - 2;
    }

    indices[index++] = bottomCorner;
    indices[index++] = bottomCorner + length;

    if (!southCap) {
      var bottomLeftCorner = width + bottomCorner - 1;
      indices[index++] = bottomLeftCorner;
      indices[index] = bottomLeftCorner + length;
    }

    geo.indices = indices;

    return geo;
  }

  /**
   * A description of the outline of a a cartographic rectangle on an ellipsoid centered at the origin.
   *
   * @alias RectangleOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Rectangle} options.rectangle A cartographic rectangle with north, south, east and west properties in radians.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid on which the rectangle lies.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number} [options.height=0.0] The distance in meters between the rectangle and the ellipsoid surface.
   * @param {Number} [options.rotation=0.0] The rotation of the rectangle, in radians. A positive rotation is counter-clockwise.
   * @param {Number} [options.extrudedHeight] The distance in meters between the rectangle's extruded face and the ellipsoid surface.
   *
   * @exception {DeveloperError} <code>options.rectangle.north</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
   * @exception {DeveloperError} <code>options.rectangle.south</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
   * @exception {DeveloperError} <code>options.rectangle.east</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
   * @exception {DeveloperError} <code>options.rectangle.west</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
   * @exception {DeveloperError} <code>options.rectangle.north</code> must be greater than <code>rectangle.south</code>.
   *
   * @see RectangleOutlineGeometry#createGeometry
   *
   * @example
   * var rectangle = new Cesium.RectangleOutlineGeometry({
   *   ellipsoid : Cesium.Ellipsoid.WGS84,
   *   rectangle : Cesium.Rectangle.fromDegrees(-80.0, 39.0, -74.0, 42.0),
   *   height : 10000.0
   * });
   * var geometry = Cesium.RectangleOutlineGeometry.createGeometry(rectangle);
   */
  function RectangleOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var rectangle = options.rectangle;
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    var rotation = defaultValue(options.rotation, 0.0);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(rectangle)) {
      throw new DeveloperError("rectangle is required.");
    }
    Rectangle.validate(rectangle);
    if (rectangle.north < rectangle.south) {
      throw new DeveloperError(
        "options.rectangle.north must be greater than options.rectangle.south"
      );
    }
    //>>includeEnd('debug');

    var height = defaultValue(options.height, 0.0);
    var extrudedHeight = defaultValue(options.extrudedHeight, height);

    this._rectangle = Rectangle.clone(rectangle);
    this._granularity = granularity;
    this._ellipsoid = ellipsoid;
    this._surfaceHeight = Math.max(height, extrudedHeight);
    this._rotation = rotation;
    this._extrudedHeight = Math.min(height, extrudedHeight);
    this._offsetAttribute = options.offsetAttribute;
    this._workerName = "createRectangleOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  RectangleOutlineGeometry.packedLength =
    Rectangle.packedLength + Ellipsoid.packedLength + 5;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {RectangleOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  RectangleOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }

    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    Rectangle.pack(value._rectangle, array, startingIndex);
    startingIndex += Rectangle.packedLength;

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex++] = value._granularity;
    array[startingIndex++] = value._surfaceHeight;
    array[startingIndex++] = value._rotation;
    array[startingIndex++] = value._extrudedHeight;
    array[startingIndex] = defaultValue(value._offsetAttribute, -1);

    return array;
  };

  var scratchRectangle$1 = new Rectangle();
  var scratchEllipsoid$b = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchOptions$j = {
    rectangle: scratchRectangle$1,
    ellipsoid: scratchEllipsoid$b,
    granularity: undefined,
    height: undefined,
    rotation: undefined,
    extrudedHeight: undefined,
    offsetAttribute: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {RectangleOutlineGeometry} [result] The object into which to store the result.
   * @returns {RectangleOutlineGeometry} The modified result parameter or a new Quaternion instance if one was not provided.
   */
  RectangleOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var rectangle = Rectangle.unpack(array, startingIndex, scratchRectangle$1);
    startingIndex += Rectangle.packedLength;

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$b);
    startingIndex += Ellipsoid.packedLength;

    var granularity = array[startingIndex++];
    var height = array[startingIndex++];
    var rotation = array[startingIndex++];
    var extrudedHeight = array[startingIndex++];
    var offsetAttribute = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$j.granularity = granularity;
      scratchOptions$j.height = height;
      scratchOptions$j.rotation = rotation;
      scratchOptions$j.extrudedHeight = extrudedHeight;
      scratchOptions$j.offsetAttribute =
        offsetAttribute === -1 ? undefined : offsetAttribute;

      return new RectangleOutlineGeometry(scratchOptions$j);
    }

    result._rectangle = Rectangle.clone(rectangle, result._rectangle);
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._surfaceHeight = height;
    result._rotation = rotation;
    result._extrudedHeight = extrudedHeight;
    result._offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;

    return result;
  };

  var nwScratch$1 = new Cartographic();
  /**
   * Computes the geometric representation of an outline of a rectangle, including its vertices, indices, and a bounding sphere.
   *
   * @param {RectangleOutlineGeometry} rectangleGeometry A description of the rectangle outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   *
   * @exception {DeveloperError} Rotated rectangle is invalid.
   */
  RectangleOutlineGeometry.createGeometry = function (rectangleGeometry) {
    var rectangle = rectangleGeometry._rectangle;
    var ellipsoid = rectangleGeometry._ellipsoid;
    var computedOptions = RectangleGeometryLibrary.computeOptions(
      rectangle,
      rectangleGeometry._granularity,
      rectangleGeometry._rotation,
      0,
      rectangleScratch$3,
      nwScratch$1
    );

    var geometry;
    var boundingSphere;

    if (
      CesiumMath.equalsEpsilon(
        rectangle.north,
        rectangle.south,
        CesiumMath.EPSILON10
      ) ||
      CesiumMath.equalsEpsilon(
        rectangle.east,
        rectangle.west,
        CesiumMath.EPSILON10
      )
    ) {
      return undefined;
    }

    var surfaceHeight = rectangleGeometry._surfaceHeight;
    var extrudedHeight = rectangleGeometry._extrudedHeight;
    var extrude = !CesiumMath.equalsEpsilon(
      surfaceHeight,
      extrudedHeight,
      0,
      CesiumMath.EPSILON2
    );
    var offsetValue;
    if (extrude) {
      geometry = constructExtrudedRectangle$1(rectangleGeometry, computedOptions);
      if (defined(rectangleGeometry._offsetAttribute)) {
        var size = geometry.attributes.position.values.length / 3;
        var offsetAttribute = new Uint8Array(size);
        if (rectangleGeometry._offsetAttribute === GeometryOffsetAttribute$1.TOP) {
          offsetAttribute = arrayFill(offsetAttribute, 1, 0, size / 2);
        } else {
          offsetValue =
            rectangleGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
              ? 0
              : 1;
          offsetAttribute = arrayFill(offsetAttribute, offsetValue);
        }

        geometry.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: offsetAttribute,
        });
      }
      var topBS = BoundingSphere.fromRectangle3D(
        rectangle,
        ellipsoid,
        surfaceHeight,
        topBoundingSphere$3
      );
      var bottomBS = BoundingSphere.fromRectangle3D(
        rectangle,
        ellipsoid,
        extrudedHeight,
        bottomBoundingSphere$3
      );
      boundingSphere = BoundingSphere.union(topBS, bottomBS);
    } else {
      geometry = constructRectangle$1(rectangleGeometry, computedOptions);
      geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(
        geometry.attributes.position.values,
        surfaceHeight,
        ellipsoid,
        false
      );

      if (defined(rectangleGeometry._offsetAttribute)) {
        var length = geometry.attributes.position.values.length;
        var applyOffset = new Uint8Array(length / 3);
        offsetValue =
          rectangleGeometry._offsetAttribute === GeometryOffsetAttribute$1.NONE
            ? 0
            : 1;
        arrayFill(applyOffset, offsetValue);
        geometry.attributes.applyOffset = new GeometryAttribute({
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          componentsPerAttribute: 1,
          values: applyOffset,
        });
      }

      boundingSphere = BoundingSphere.fromRectangle3D(
        rectangle,
        ellipsoid,
        surfaceHeight
      );
    }

    return new Geometry({
      attributes: geometry.attributes,
      indices: geometry.indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: boundingSphere,
      offsetAttribute: rectangleGeometry._offsetAttribute,
    });
  };

  /**
   * Constants for identifying well-known reference frames.
   *
   * @enum {Number}
   */
  var ReferenceFrame = {
    /**
     * The fixed frame.
     *
     * @type {Number}
     * @constant
     */
    FIXED: 0,

    /**
     * The inertial frame.
     *
     * @type {Number}
     * @constant
     */
    INERTIAL: 1,
  };
  var ReferenceFrame$1 = Object.freeze(ReferenceFrame);

  /**
   * This enumerated type is for classifying mouse events: down, up, click, double click, move and move while a button is held down.
   *
   * @enum {Number}
   */
  var ScreenSpaceEventType = {
    /**
     * Represents a mouse left button down event.
     *
     * @type {Number}
     * @constant
     */
    LEFT_DOWN: 0,

    /**
     * Represents a mouse left button up event.
     *
     * @type {Number}
     * @constant
     */
    LEFT_UP: 1,

    /**
     * Represents a mouse left click event.
     *
     * @type {Number}
     * @constant
     */
    LEFT_CLICK: 2,

    /**
     * Represents a mouse left double click event.
     *
     * @type {Number}
     * @constant
     */
    LEFT_DOUBLE_CLICK: 3,

    /**
     * Represents a mouse left button down event.
     *
     * @type {Number}
     * @constant
     */
    RIGHT_DOWN: 5,

    /**
     * Represents a mouse right button up event.
     *
     * @type {Number}
     * @constant
     */
    RIGHT_UP: 6,

    /**
     * Represents a mouse right click event.
     *
     * @type {Number}
     * @constant
     */
    RIGHT_CLICK: 7,

    /**
     * Represents a mouse middle button down event.
     *
     * @type {Number}
     * @constant
     */
    MIDDLE_DOWN: 10,

    /**
     * Represents a mouse middle button up event.
     *
     * @type {Number}
     * @constant
     */
    MIDDLE_UP: 11,

    /**
     * Represents a mouse middle click event.
     *
     * @type {Number}
     * @constant
     */
    MIDDLE_CLICK: 12,

    /**
     * Represents a mouse move event.
     *
     * @type {Number}
     * @constant
     */
    MOUSE_MOVE: 15,

    /**
     * Represents a mouse wheel event.
     *
     * @type {Number}
     * @constant
     */
    WHEEL: 16,

    /**
     * Represents the start of a two-finger event on a touch surface.
     *
     * @type {Number}
     * @constant
     */
    PINCH_START: 17,

    /**
     * Represents the end of a two-finger event on a touch surface.
     *
     * @type {Number}
     * @constant
     */
    PINCH_END: 18,

    /**
     * Represents a change of a two-finger event on a touch surface.
     *
     * @type {Number}
     * @constant
     */
    PINCH_MOVE: 19,
  };
  var ScreenSpaceEventType$1 = Object.freeze(ScreenSpaceEventType);

  function getPosition$1(screenSpaceEventHandler, event, result) {
    var element = screenSpaceEventHandler._element;
    if (element === document) {
      result.x = event.clientX;
      result.y = event.clientY;
      return result;
    }

    var rect = element.getBoundingClientRect();
    result.x = event.clientX - rect.left;
    result.y = event.clientY - rect.top;
    return result;
  }

  function getInputEventKey(type, modifier) {
    var key = type;
    if (defined(modifier)) {
      key += "+" + modifier;
    }
    return key;
  }

  function getModifier(event) {
    if (event.shiftKey) {
      return KeyboardEventModifier$1.SHIFT;
    } else if (event.ctrlKey) {
      return KeyboardEventModifier$1.CTRL;
    } else if (event.altKey) {
      return KeyboardEventModifier$1.ALT;
    }

    return undefined;
  }

  var MouseButton = {
    LEFT: 0,
    MIDDLE: 1,
    RIGHT: 2,
  };

  function registerListener(screenSpaceEventHandler, domType, element, callback) {
    function listener(e) {
      callback(screenSpaceEventHandler, e);
    }

    if (FeatureDetection.isInternetExplorer()) {
      element.addEventListener(domType, listener, false);
    } else {
      element.addEventListener(domType, listener, {
        capture: false,
        passive: false,
      });
    }

    screenSpaceEventHandler._removalFunctions.push(function () {
      element.removeEventListener(domType, listener, false);
    });
  }

  function registerListeners(screenSpaceEventHandler) {
    var element = screenSpaceEventHandler._element;

    // some listeners may be registered on the document, so we still get events even after
    // leaving the bounds of element.
    // this is affected by the existence of an undocumented disableRootEvents property on element.
    var alternateElement = !defined(element.disableRootEvents)
      ? document
      : element;

    if (FeatureDetection.supportsPointerEvents()) {
      registerListener(
        screenSpaceEventHandler,
        "pointerdown",
        element,
        handlePointerDown
      );
      registerListener(
        screenSpaceEventHandler,
        "pointerup",
        element,
        handlePointerUp
      );
      registerListener(
        screenSpaceEventHandler,
        "pointermove",
        element,
        handlePointerMove
      );
      registerListener(
        screenSpaceEventHandler,
        "pointercancel",
        element,
        handlePointerUp
      );
    } else {
      registerListener(
        screenSpaceEventHandler,
        "mousedown",
        element,
        handleMouseDown
      );
      registerListener(
        screenSpaceEventHandler,
        "mouseup",
        alternateElement,
        handleMouseUp
      );
      registerListener(
        screenSpaceEventHandler,
        "mousemove",
        alternateElement,
        handleMouseMove
      );
      registerListener(
        screenSpaceEventHandler,
        "touchstart",
        element,
        handleTouchStart
      );
      registerListener(
        screenSpaceEventHandler,
        "touchend",
        alternateElement,
        handleTouchEnd
      );
      registerListener(
        screenSpaceEventHandler,
        "touchmove",
        alternateElement,
        handleTouchMove
      );
      registerListener(
        screenSpaceEventHandler,
        "touchcancel",
        alternateElement,
        handleTouchEnd
      );
    }

    registerListener(
      screenSpaceEventHandler,
      "dblclick",
      element,
      handleDblClick
    );

    // detect available wheel event
    var wheelEvent;
    if ("onwheel" in element) {
      // spec event type
      wheelEvent = "wheel";
    } else if (document.onmousewheel !== undefined) {
      // legacy event type
      wheelEvent = "mousewheel";
    } else {
      // older Firefox
      wheelEvent = "DOMMouseScroll";
    }

    registerListener(screenSpaceEventHandler, wheelEvent, element, handleWheel);
  }

  function unregisterListeners(screenSpaceEventHandler) {
    var removalFunctions = screenSpaceEventHandler._removalFunctions;
    for (var i = 0; i < removalFunctions.length; ++i) {
      removalFunctions[i]();
    }
  }

  var mouseDownEvent = {
    position: new Cartesian2(),
  };

  function gotTouchEvent(screenSpaceEventHandler) {
    screenSpaceEventHandler._lastSeenTouchEvent = getTimestamp$1();
  }

  function canProcessMouseEvent(screenSpaceEventHandler) {
    return (
      getTimestamp$1() - screenSpaceEventHandler._lastSeenTouchEvent >
      ScreenSpaceEventHandler.mouseEmulationIgnoreMilliseconds
    );
  }

  function checkPixelTolerance(startPosition, endPosition, pixelTolerance) {
    var xDiff = startPosition.x - endPosition.x;
    var yDiff = startPosition.y - endPosition.y;
    var totalPixels = Math.sqrt(xDiff * xDiff + yDiff * yDiff);

    return totalPixels < pixelTolerance;
  }

  function handleMouseDown(screenSpaceEventHandler, event) {
    if (!canProcessMouseEvent(screenSpaceEventHandler)) {
      return;
    }

    var button = event.button;
    screenSpaceEventHandler._buttonDown[button] = true;

    var screenSpaceEventType;
    if (button === MouseButton.LEFT) {
      screenSpaceEventType = ScreenSpaceEventType$1.LEFT_DOWN;
    } else if (button === MouseButton.MIDDLE) {
      screenSpaceEventType = ScreenSpaceEventType$1.MIDDLE_DOWN;
    } else if (button === MouseButton.RIGHT) {
      screenSpaceEventType = ScreenSpaceEventType$1.RIGHT_DOWN;
    } else {
      return;
    }

    var position = getPosition$1(
      screenSpaceEventHandler,
      event,
      screenSpaceEventHandler._primaryPosition
    );
    Cartesian2.clone(position, screenSpaceEventHandler._primaryStartPosition);
    Cartesian2.clone(position, screenSpaceEventHandler._primaryPreviousPosition);

    var modifier = getModifier(event);

    var action = screenSpaceEventHandler.getInputAction(
      screenSpaceEventType,
      modifier
    );

    if (defined(action)) {
      Cartesian2.clone(position, mouseDownEvent.position);

      action(mouseDownEvent);

      event.preventDefault();
    }
  }

  var mouseUpEvent = {
    position: new Cartesian2(),
  };
  var mouseClickEvent = {
    position: new Cartesian2(),
  };

  function cancelMouseEvent(
    screenSpaceEventHandler,
    screenSpaceEventType,
    clickScreenSpaceEventType,
    event
  ) {
    var modifier = getModifier(event);

    var action = screenSpaceEventHandler.getInputAction(
      screenSpaceEventType,
      modifier
    );
    var clickAction = screenSpaceEventHandler.getInputAction(
      clickScreenSpaceEventType,
      modifier
    );

    if (defined(action) || defined(clickAction)) {
      var position = getPosition$1(
        screenSpaceEventHandler,
        event,
        screenSpaceEventHandler._primaryPosition
      );

      if (defined(action)) {
        Cartesian2.clone(position, mouseUpEvent.position);

        action(mouseUpEvent);
      }

      if (defined(clickAction)) {
        var startPosition = screenSpaceEventHandler._primaryStartPosition;
        if (
          checkPixelTolerance(
            startPosition,
            position,
            screenSpaceEventHandler._clickPixelTolerance
          )
        ) {
          Cartesian2.clone(position, mouseClickEvent.position);

          clickAction(mouseClickEvent);
        }
      }
    }
  }

  function handleMouseUp(screenSpaceEventHandler, event) {
    if (!canProcessMouseEvent(screenSpaceEventHandler)) {
      return;
    }

    var button = event.button;

    if (
      button !== MouseButton.LEFT &&
      button !== MouseButton.MIDDLE &&
      button !== MouseButton.RIGHT
    ) {
      return;
    }

    if (screenSpaceEventHandler._buttonDown[MouseButton.LEFT]) {
      cancelMouseEvent(
        screenSpaceEventHandler,
        ScreenSpaceEventType$1.LEFT_UP,
        ScreenSpaceEventType$1.LEFT_CLICK,
        event
      );
      screenSpaceEventHandler._buttonDown[MouseButton.LEFT] = false;
    }
    if (screenSpaceEventHandler._buttonDown[MouseButton.MIDDLE]) {
      cancelMouseEvent(
        screenSpaceEventHandler,
        ScreenSpaceEventType$1.MIDDLE_UP,
        ScreenSpaceEventType$1.MIDDLE_CLICK,
        event
      );
      screenSpaceEventHandler._buttonDown[MouseButton.MIDDLE] = false;
    }
    if (screenSpaceEventHandler._buttonDown[MouseButton.RIGHT]) {
      cancelMouseEvent(
        screenSpaceEventHandler,
        ScreenSpaceEventType$1.RIGHT_UP,
        ScreenSpaceEventType$1.RIGHT_CLICK,
        event
      );
      screenSpaceEventHandler._buttonDown[MouseButton.RIGHT] = false;
    }
  }

  var mouseMoveEvent = {
    startPosition: new Cartesian2(),
    endPosition: new Cartesian2(),
  };

  function handleMouseMove(screenSpaceEventHandler, event) {
    if (!canProcessMouseEvent(screenSpaceEventHandler)) {
      return;
    }

    var modifier = getModifier(event);

    var position = getPosition$1(
      screenSpaceEventHandler,
      event,
      screenSpaceEventHandler._primaryPosition
    );
    var previousPosition = screenSpaceEventHandler._primaryPreviousPosition;

    var action = screenSpaceEventHandler.getInputAction(
      ScreenSpaceEventType$1.MOUSE_MOVE,
      modifier
    );

    if (defined(action)) {
      Cartesian2.clone(previousPosition, mouseMoveEvent.startPosition);
      Cartesian2.clone(position, mouseMoveEvent.endPosition);

      action(mouseMoveEvent);
    }

    Cartesian2.clone(position, previousPosition);

    if (
      screenSpaceEventHandler._buttonDown[MouseButton.LEFT] ||
      screenSpaceEventHandler._buttonDown[MouseButton.MIDDLE] ||
      screenSpaceEventHandler._buttonDown[MouseButton.RIGHT]
    ) {
      event.preventDefault();
    }
  }

  var mouseDblClickEvent = {
    position: new Cartesian2(),
  };

  function handleDblClick(screenSpaceEventHandler, event) {
    var button = event.button;

    var screenSpaceEventType;
    if (button === MouseButton.LEFT) {
      screenSpaceEventType = ScreenSpaceEventType$1.LEFT_DOUBLE_CLICK;
    } else {
      return;
    }

    var modifier = getModifier(event);

    var action = screenSpaceEventHandler.getInputAction(
      screenSpaceEventType,
      modifier
    );

    if (defined(action)) {
      getPosition$1(screenSpaceEventHandler, event, mouseDblClickEvent.position);

      action(mouseDblClickEvent);
    }
  }

  function handleWheel(screenSpaceEventHandler, event) {
    // currently this event exposes the delta value in terms of
    // the obsolete mousewheel event type.  so, for now, we adapt the other
    // values to that scheme.
    var delta;

    // standard wheel event uses deltaY.  sign is opposite wheelDelta.
    // deltaMode indicates what unit it is in.
    if (defined(event.deltaY)) {
      var deltaMode = event.deltaMode;
      if (deltaMode === event.DOM_DELTA_PIXEL) {
        delta = -event.deltaY;
      } else if (deltaMode === event.DOM_DELTA_LINE) {
        delta = -event.deltaY * 40;
      } else {
        // DOM_DELTA_PAGE
        delta = -event.deltaY * 120;
      }
    } else if (event.detail > 0) {
      // old Firefox versions use event.detail to count the number of clicks. The sign
      // of the integer is the direction the wheel is scrolled.
      delta = event.detail * -120;
    } else {
      delta = event.wheelDelta;
    }

    if (!defined(delta)) {
      return;
    }

    var modifier = getModifier(event);
    var action = screenSpaceEventHandler.getInputAction(
      ScreenSpaceEventType$1.WHEEL,
      modifier
    );

    if (defined(action)) {
      action(delta);

      event.preventDefault();
    }
  }

  function handleTouchStart(screenSpaceEventHandler, event) {
    gotTouchEvent(screenSpaceEventHandler);

    var changedTouches = event.changedTouches;

    var i;
    var length = changedTouches.length;
    var touch;
    var identifier;
    var positions = screenSpaceEventHandler._positions;

    for (i = 0; i < length; ++i) {
      touch = changedTouches[i];
      identifier = touch.identifier;
      positions.set(
        identifier,
        getPosition$1(screenSpaceEventHandler, touch, new Cartesian2())
      );
    }

    fireTouchEvents(screenSpaceEventHandler, event);

    var previousPositions = screenSpaceEventHandler._previousPositions;

    for (i = 0; i < length; ++i) {
      touch = changedTouches[i];
      identifier = touch.identifier;
      previousPositions.set(
        identifier,
        Cartesian2.clone(positions.get(identifier))
      );
    }
  }

  function handleTouchEnd(screenSpaceEventHandler, event) {
    gotTouchEvent(screenSpaceEventHandler);

    var changedTouches = event.changedTouches;

    var i;
    var length = changedTouches.length;
    var touch;
    var identifier;
    var positions = screenSpaceEventHandler._positions;

    for (i = 0; i < length; ++i) {
      touch = changedTouches[i];
      identifier = touch.identifier;
      positions.remove(identifier);
    }

    fireTouchEvents(screenSpaceEventHandler, event);

    var previousPositions = screenSpaceEventHandler._previousPositions;

    for (i = 0; i < length; ++i) {
      touch = changedTouches[i];
      identifier = touch.identifier;
      previousPositions.remove(identifier);
    }
  }

  var touchStartEvent = {
    position: new Cartesian2(),
  };
  var touch2StartEvent = {
    position1: new Cartesian2(),
    position2: new Cartesian2(),
  };
  var touchEndEvent = {
    position: new Cartesian2(),
  };
  var touchClickEvent = {
    position: new Cartesian2(),
  };
  var touchHoldEvent = {
    position: new Cartesian2(),
  };

  function fireTouchEvents(screenSpaceEventHandler, event) {
    var modifier = getModifier(event);
    var positions = screenSpaceEventHandler._positions;
    var numberOfTouches = positions.length;
    var action;
    var clickAction;
    var pinching = screenSpaceEventHandler._isPinching;

    if (
      numberOfTouches !== 1 &&
      screenSpaceEventHandler._buttonDown[MouseButton.LEFT]
    ) {
      // transitioning from single touch, trigger UP and might trigger CLICK
      screenSpaceEventHandler._buttonDown[MouseButton.LEFT] = false;

      if (defined(screenSpaceEventHandler._touchHoldTimer)) {
        clearTimeout(screenSpaceEventHandler._touchHoldTimer);
        screenSpaceEventHandler._touchHoldTimer = undefined;
      }

      action = screenSpaceEventHandler.getInputAction(
        ScreenSpaceEventType$1.LEFT_UP,
        modifier
      );

      if (defined(action)) {
        Cartesian2.clone(
          screenSpaceEventHandler._primaryPosition,
          touchEndEvent.position
        );

        action(touchEndEvent);
      }

      if (numberOfTouches === 0 && !screenSpaceEventHandler._isTouchHolding) {
        // releasing single touch, check for CLICK
        clickAction = screenSpaceEventHandler.getInputAction(
          ScreenSpaceEventType$1.LEFT_CLICK,
          modifier
        );

        if (defined(clickAction)) {
          var startPosition = screenSpaceEventHandler._primaryStartPosition;
          var endPosition = screenSpaceEventHandler._previousPositions.values[0];
          if (
            checkPixelTolerance(
              startPosition,
              endPosition,
              screenSpaceEventHandler._clickPixelTolerance
            )
          ) {
            Cartesian2.clone(
              screenSpaceEventHandler._primaryPosition,
              touchClickEvent.position
            );

            clickAction(touchClickEvent);
          }
        }
      }

      screenSpaceEventHandler._isTouchHolding = false;

      // Otherwise don't trigger CLICK, because we are adding more touches.
    }

    if (numberOfTouches === 0 && pinching) {
      // transitioning from pinch, trigger PINCH_END
      screenSpaceEventHandler._isPinching = false;

      action = screenSpaceEventHandler.getInputAction(
        ScreenSpaceEventType$1.PINCH_END,
        modifier
      );

      if (defined(action)) {
        action();
      }
    }

    if (numberOfTouches === 1 && !pinching) {
      // transitioning to single touch, trigger DOWN
      var position = positions.values[0];
      Cartesian2.clone(position, screenSpaceEventHandler._primaryPosition);
      Cartesian2.clone(position, screenSpaceEventHandler._primaryStartPosition);
      Cartesian2.clone(
        position,
        screenSpaceEventHandler._primaryPreviousPosition
      );

      screenSpaceEventHandler._buttonDown[MouseButton.LEFT] = true;

      action = screenSpaceEventHandler.getInputAction(
        ScreenSpaceEventType$1.LEFT_DOWN,
        modifier
      );

      if (defined(action)) {
        Cartesian2.clone(position, touchStartEvent.position);

        action(touchStartEvent);
      }

      screenSpaceEventHandler._touchHoldTimer = setTimeout(function () {
        if (!screenSpaceEventHandler.isDestroyed()) {
          screenSpaceEventHandler._touchHoldTimer = undefined;
          screenSpaceEventHandler._isTouchHolding = true;

          clickAction = screenSpaceEventHandler.getInputAction(
            ScreenSpaceEventType$1.RIGHT_CLICK,
            modifier
          );

          if (defined(clickAction)) {
            var startPosition = screenSpaceEventHandler._primaryStartPosition;
            var endPosition =
              screenSpaceEventHandler._previousPositions.values[0];
            if (
              checkPixelTolerance(
                startPosition,
                endPosition,
                screenSpaceEventHandler._holdPixelTolerance
              )
            ) {
              Cartesian2.clone(
                screenSpaceEventHandler._primaryPosition,
                touchHoldEvent.position
              );

              clickAction(touchHoldEvent);
            }
          }
        }
      }, ScreenSpaceEventHandler.touchHoldDelayMilliseconds);

      event.preventDefault();
    }

    if (numberOfTouches === 2 && !pinching) {
      // transitioning to pinch, trigger PINCH_START
      screenSpaceEventHandler._isPinching = true;

      action = screenSpaceEventHandler.getInputAction(
        ScreenSpaceEventType$1.PINCH_START,
        modifier
      );

      if (defined(action)) {
        Cartesian2.clone(positions.values[0], touch2StartEvent.position1);
        Cartesian2.clone(positions.values[1], touch2StartEvent.position2);

        action(touch2StartEvent);

        // Touch-enabled devices, in particular iOS can have many default behaviours for
        // "pinch" events, which can still be executed unless we prevent them here.
        event.preventDefault();
      }
    }
  }

  function handleTouchMove(screenSpaceEventHandler, event) {
    gotTouchEvent(screenSpaceEventHandler);

    var changedTouches = event.changedTouches;

    var i;
    var length = changedTouches.length;
    var touch;
    var identifier;
    var positions = screenSpaceEventHandler._positions;

    for (i = 0; i < length; ++i) {
      touch = changedTouches[i];
      identifier = touch.identifier;
      var position = positions.get(identifier);
      if (defined(position)) {
        getPosition$1(screenSpaceEventHandler, touch, position);
      }
    }

    fireTouchMoveEvents(screenSpaceEventHandler, event);

    var previousPositions = screenSpaceEventHandler._previousPositions;

    for (i = 0; i < length; ++i) {
      touch = changedTouches[i];
      identifier = touch.identifier;
      Cartesian2.clone(
        positions.get(identifier),
        previousPositions.get(identifier)
      );
    }
  }

  var touchMoveEvent = {
    startPosition: new Cartesian2(),
    endPosition: new Cartesian2(),
  };
  var touchPinchMovementEvent = {
    distance: {
      startPosition: new Cartesian2(),
      endPosition: new Cartesian2(),
    },
    angleAndHeight: {
      startPosition: new Cartesian2(),
      endPosition: new Cartesian2(),
    },
  };

  function fireTouchMoveEvents(screenSpaceEventHandler, event) {
    var modifier = getModifier(event);
    var positions = screenSpaceEventHandler._positions;
    var previousPositions = screenSpaceEventHandler._previousPositions;
    var numberOfTouches = positions.length;
    var action;

    if (
      numberOfTouches === 1 &&
      screenSpaceEventHandler._buttonDown[MouseButton.LEFT]
    ) {
      // moving single touch
      var position = positions.values[0];
      Cartesian2.clone(position, screenSpaceEventHandler._primaryPosition);

      var previousPosition = screenSpaceEventHandler._primaryPreviousPosition;

      action = screenSpaceEventHandler.getInputAction(
        ScreenSpaceEventType$1.MOUSE_MOVE,
        modifier
      );

      if (defined(action)) {
        Cartesian2.clone(previousPosition, touchMoveEvent.startPosition);
        Cartesian2.clone(position, touchMoveEvent.endPosition);

        action(touchMoveEvent);
      }

      Cartesian2.clone(position, previousPosition);

      event.preventDefault();
    } else if (numberOfTouches === 2 && screenSpaceEventHandler._isPinching) {
      // moving pinch

      action = screenSpaceEventHandler.getInputAction(
        ScreenSpaceEventType$1.PINCH_MOVE,
        modifier
      );
      if (defined(action)) {
        var position1 = positions.values[0];
        var position2 = positions.values[1];
        var previousPosition1 = previousPositions.values[0];
        var previousPosition2 = previousPositions.values[1];

        var dX = position2.x - position1.x;
        var dY = position2.y - position1.y;
        var dist = Math.sqrt(dX * dX + dY * dY) * 0.25;

        var prevDX = previousPosition2.x - previousPosition1.x;
        var prevDY = previousPosition2.y - previousPosition1.y;
        var prevDist = Math.sqrt(prevDX * prevDX + prevDY * prevDY) * 0.25;

        var cY = (position2.y + position1.y) * 0.125;
        var prevCY = (previousPosition2.y + previousPosition1.y) * 0.125;
        var angle = Math.atan2(dY, dX);
        var prevAngle = Math.atan2(prevDY, prevDX);

        Cartesian2.fromElements(
          0.0,
          prevDist,
          touchPinchMovementEvent.distance.startPosition
        );
        Cartesian2.fromElements(
          0.0,
          dist,
          touchPinchMovementEvent.distance.endPosition
        );

        Cartesian2.fromElements(
          prevAngle,
          prevCY,
          touchPinchMovementEvent.angleAndHeight.startPosition
        );
        Cartesian2.fromElements(
          angle,
          cY,
          touchPinchMovementEvent.angleAndHeight.endPosition
        );

        action(touchPinchMovementEvent);
      }
    }
  }

  function handlePointerDown(screenSpaceEventHandler, event) {
    event.target.setPointerCapture(event.pointerId);

    if (event.pointerType === "touch") {
      var positions = screenSpaceEventHandler._positions;

      var identifier = event.pointerId;
      positions.set(
        identifier,
        getPosition$1(screenSpaceEventHandler, event, new Cartesian2())
      );

      fireTouchEvents(screenSpaceEventHandler, event);

      var previousPositions = screenSpaceEventHandler._previousPositions;
      previousPositions.set(
        identifier,
        Cartesian2.clone(positions.get(identifier))
      );
    } else {
      handleMouseDown(screenSpaceEventHandler, event);
    }
  }

  function handlePointerUp(screenSpaceEventHandler, event) {
    if (event.pointerType === "touch") {
      var positions = screenSpaceEventHandler._positions;

      var identifier = event.pointerId;
      positions.remove(identifier);

      fireTouchEvents(screenSpaceEventHandler, event);

      var previousPositions = screenSpaceEventHandler._previousPositions;
      previousPositions.remove(identifier);
    } else {
      handleMouseUp(screenSpaceEventHandler, event);
    }
  }

  function handlePointerMove(screenSpaceEventHandler, event) {
    if (event.pointerType === "touch") {
      var positions = screenSpaceEventHandler._positions;

      var identifier = event.pointerId;
      var position = positions.get(identifier);
      if (!defined(position)) {
        return;
      }

      getPosition$1(screenSpaceEventHandler, event, position);
      fireTouchMoveEvents(screenSpaceEventHandler, event);

      var previousPositions = screenSpaceEventHandler._previousPositions;
      Cartesian2.clone(
        positions.get(identifier),
        previousPositions.get(identifier)
      );
    } else {
      handleMouseMove(screenSpaceEventHandler, event);
    }
  }

  /**
   * Handles user input events. Custom functions can be added to be executed on
   * when the user enters input.
   *
   * @alias ScreenSpaceEventHandler
   *
   * @param {HTMLCanvasElement} [element=document] The element to add events to.
   *
   * @constructor
   */
  function ScreenSpaceEventHandler(element) {
    this._inputEvents = {};
    this._buttonDown = {
      LEFT: false,
      MIDDLE: false,
      RIGHT: false,
    };
    this._isPinching = false;
    this._isTouchHolding = false;
    this._lastSeenTouchEvent = -ScreenSpaceEventHandler.mouseEmulationIgnoreMilliseconds;

    this._primaryStartPosition = new Cartesian2();
    this._primaryPosition = new Cartesian2();
    this._primaryPreviousPosition = new Cartesian2();

    this._positions = new AssociativeArray();
    this._previousPositions = new AssociativeArray();

    this._removalFunctions = [];

    this._touchHoldTimer = undefined;

    // TODO: Revisit when doing mobile development. May need to be configurable
    // or determined based on the platform?
    this._clickPixelTolerance = 5;
    this._holdPixelTolerance = 25;

    this._element = defaultValue(element, document);

    registerListeners(this);
  }

  /**
   * Set a function to be executed on an input event.
   *
   * @param {Function} action Function to be executed when the input event occurs.
   * @param {Number} type The ScreenSpaceEventType of input event.
   * @param {Number} [modifier] A KeyboardEventModifier key that is held when a <code>type</code>
   * event occurs.
   *
   * @see ScreenSpaceEventHandler#getInputAction
   * @see ScreenSpaceEventHandler#removeInputAction
   */
  ScreenSpaceEventHandler.prototype.setInputAction = function (
    action,
    type,
    modifier
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(action)) {
      throw new DeveloperError("action is required.");
    }
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getInputEventKey(type, modifier);
    this._inputEvents[key] = action;
  };

  /**
   * Returns the function to be executed on an input event.
   *
   * @param {Number} type The ScreenSpaceEventType of input event.
   * @param {Number} [modifier] A KeyboardEventModifier key that is held when a <code>type</code>
   * event occurs.
   *
   * @returns {Function} The function to be executed on an input event.
   *
   * @see ScreenSpaceEventHandler#setInputAction
   * @see ScreenSpaceEventHandler#removeInputAction
   */
  ScreenSpaceEventHandler.prototype.getInputAction = function (type, modifier) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getInputEventKey(type, modifier);
    return this._inputEvents[key];
  };

  /**
   * Removes the function to be executed on an input event.
   *
   * @param {Number} type The ScreenSpaceEventType of input event.
   * @param {Number} [modifier] A KeyboardEventModifier key that is held when a <code>type</code>
   * event occurs.
   *
   * @see ScreenSpaceEventHandler#getInputAction
   * @see ScreenSpaceEventHandler#setInputAction
   */
  ScreenSpaceEventHandler.prototype.removeInputAction = function (
    type,
    modifier
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getInputEventKey(type, modifier);
    delete this._inputEvents[key];
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see ScreenSpaceEventHandler#destroy
   */
  ScreenSpaceEventHandler.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes listeners held by this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * handler = handler && handler.destroy();
   *
   * @see ScreenSpaceEventHandler#isDestroyed
   */
  ScreenSpaceEventHandler.prototype.destroy = function () {
    unregisterListeners(this);

    return destroyObject(this);
  };

  /**
   * The amount of time, in milliseconds, that mouse events will be disabled after
   * receiving any touch events, such that any emulated mouse events will be ignored.
   * @type {Number}
   * @default 800
   */
  ScreenSpaceEventHandler.mouseEmulationIgnoreMilliseconds = 800;

  /**
   * The amount of time, in milliseconds, before a touch on the screen becomes a
   * touch and hold.
   * @type {Number}
   * @default 1500
   */
  ScreenSpaceEventHandler.touchHoldDelayMilliseconds = 1500;

  /**
   * Value and type information for per-instance geometry attribute that determines if the geometry instance will be shown.
   *
   * @alias ShowGeometryInstanceAttribute
   * @constructor
   *
   * @param {Boolean} [show=true] Determines if the geometry instance will be shown.
   *
   *
   * @example
   * var instance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.BoxGeometry({
   *     vertexFormat : Cesium.VertexFormat.POSITION_AND_NORMAL,
   *     minimum : new Cesium.Cartesian3(-250000.0, -250000.0, -250000.0),
   *     maximum : new Cesium.Cartesian3(250000.0, 250000.0, 250000.0)
   *   }),
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 1000000.0), new Cesium.Matrix4()),
   *   id : 'box',
   *   attributes : {
   *     show : new Cesium.ShowGeometryInstanceAttribute(false)
   *   }
   * });
   *
   * @see GeometryInstance
   * @see GeometryInstanceAttribute
   */
  function ShowGeometryInstanceAttribute(show) {
    show = defaultValue(show, true);

    /**
     * The values for the attributes stored in a typed array.
     *
     * @type Uint8Array
     *
     * @default [1.0]
     */
    this.value = ShowGeometryInstanceAttribute.toValue(show);
  }

  Object.defineProperties(ShowGeometryInstanceAttribute.prototype, {
    /**
     * The datatype of each component in the attribute, e.g., individual elements in
     * {@link ColorGeometryInstanceAttribute#value}.
     *
     * @memberof ShowGeometryInstanceAttribute.prototype
     *
     * @type {ComponentDatatype}
     * @readonly
     *
     * @default {@link ComponentDatatype.UNSIGNED_BYTE}
     */
    componentDatatype: {
      get: function () {
        return ComponentDatatype$1.UNSIGNED_BYTE;
      },
    },

    /**
     * The number of components in the attributes, i.e., {@link ColorGeometryInstanceAttribute#value}.
     *
     * @memberof ShowGeometryInstanceAttribute.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @default 1
     */
    componentsPerAttribute: {
      get: function () {
        return 1;
      },
    },

    /**
     * When <code>true</code> and <code>componentDatatype</code> is an integer format,
     * indicate that the components should be mapped to the range [0, 1] (unsigned)
     * or [-1, 1] (signed) when they are accessed as floating-point for rendering.
     *
     * @memberof ShowGeometryInstanceAttribute.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    normalize: {
      get: function () {
        return false;
      },
    },
  });

  /**
   * Converts a boolean show to a typed array that can be used to assign a show attribute.
   *
   * @param {Boolean} show The show value.
   * @param {Uint8Array} [result] The array to store the result in, if undefined a new instance will be created.
   * @returns {Uint8Array} The modified result parameter or a new instance if result was undefined.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true, attributes.show);
   */
  ShowGeometryInstanceAttribute.toValue = function (show, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(show)) {
      throw new DeveloperError("show is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Uint8Array([show]);
    }
    result[0] = show;
    return result;
  };

  /**
   * Contains functions for finding the Cartesian coordinates of the sun and the moon in the
   * Earth-centered inertial frame.
   *
   * @namespace Simon1994PlanetaryPositions
   */
  var Simon1994PlanetaryPositions = {};

  function computeTdbMinusTtSpice(daysSinceJ2000InTerrestrialTime) {
    /* STK Comments ------------------------------------------------------
     * This function uses constants designed to be consistent with
     * the SPICE Toolkit from JPL version N0051 (unitim.c)
     * M0 = 6.239996
     * M0Dot = 1.99096871e-7 rad/s = 0.01720197 rad/d
     * EARTH_ECC = 1.671e-2
     * TDB_AMPL = 1.657e-3 secs
     *--------------------------------------------------------------------*/

    //* Values taken as specified in STK Comments except: 0.01720197 rad/day = 1.99096871e-7 rad/sec
    //* Here we use the more precise value taken from the SPICE value 1.99096871e-7 rad/sec converted to rad/day
    //* All other constants are consistent with the SPICE implementation of the TDB conversion
    //* except where we treat the independent time parameter to be in TT instead of TDB.
    //* This is an approximation made to facilitate performance due to the higher prevalance of
    //* the TT2TDB conversion over TDB2TT in order to avoid having to iterate when converting to TDB for the JPL ephemeris.
    //* Days are used instead of seconds to provide a slight improvement in numerical precision.

    //* For more information see:
    //* http://www.cv.nrao.edu/~rfisher/Ephemerides/times.html#TDB
    //* ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf

    var g = 6.239996 + 0.0172019696544 * daysSinceJ2000InTerrestrialTime;
    return 1.657e-3 * Math.sin(g + 1.671e-2 * Math.sin(g));
  }

  var TdtMinusTai$1 = 32.184;
  var J2000d$1 = 2451545;
  function taiToTdb(date, result) {
    //Converts TAI to TT
    result = JulianDate.addSeconds(date, TdtMinusTai$1, result);

    //Converts TT to TDB
    var days = JulianDate.totalDays(result) - J2000d$1;
    result = JulianDate.addSeconds(result, computeTdbMinusTtSpice(days), result);

    return result;
  }

  var epoch = new JulianDate(2451545, 0, TimeStandard$1.TAI); //Actually TDB (not TAI)
  var MetersPerKilometer = 1000.0;
  var RadiansPerDegree = CesiumMath.RADIANS_PER_DEGREE;
  var RadiansPerArcSecond = CesiumMath.RADIANS_PER_ARCSECOND;
  var MetersPerAstronomicalUnit = 1.4959787e11; // IAU 1976 value

  var perifocalToEquatorial = new Matrix3();
  function elementsToCartesian(
    semimajorAxis,
    eccentricity,
    inclination,
    longitudeOfPerigee,
    longitudeOfNode,
    meanLongitude,
    result
  ) {
    if (inclination < 0.0) {
      inclination = -inclination;
      longitudeOfNode += CesiumMath.PI;
    }

    //>>includeStart('debug', pragmas.debug);
    if (inclination < 0 || inclination > CesiumMath.PI) {
      throw new DeveloperError(
        "The inclination is out of range. Inclination must be greater than or equal to zero and less than or equal to Pi radians."
      );
    }
    //>>includeEnd('debug')

    var radiusOfPeriapsis = semimajorAxis * (1.0 - eccentricity);
    var argumentOfPeriapsis = longitudeOfPerigee - longitudeOfNode;
    var rightAscensionOfAscendingNode = longitudeOfNode;
    var trueAnomaly = meanAnomalyToTrueAnomaly(
      meanLongitude - longitudeOfPerigee,
      eccentricity
    );
    var type = chooseOrbit(eccentricity, 0.0);

    //>>includeStart('debug', pragmas.debug);
    if (
      type === "Hyperbolic" &&
      Math.abs(CesiumMath.negativePiToPi(trueAnomaly)) >=
        Math.acos(-1.0 / eccentricity)
    ) {
      throw new DeveloperError(
        "The true anomaly of the hyperbolic orbit lies outside of the bounds of the hyperbola."
      );
    }
    //>>includeEnd('debug')

    perifocalToCartesianMatrix(
      argumentOfPeriapsis,
      inclination,
      rightAscensionOfAscendingNode,
      perifocalToEquatorial
    );
    var semilatus = radiusOfPeriapsis * (1.0 + eccentricity);
    var costheta = Math.cos(trueAnomaly);
    var sintheta = Math.sin(trueAnomaly);

    var denom = 1.0 + eccentricity * costheta;

    //>>includeStart('debug', pragmas.debug);
    if (denom <= CesiumMath.Epsilon10) {
      throw new DeveloperError("elements cannot be converted to cartesian");
    }
    //>>includeEnd('debug')

    var radius = semilatus / denom;
    if (!defined(result)) {
      result = new Cartesian3(radius * costheta, radius * sintheta, 0.0);
    } else {
      result.x = radius * costheta;
      result.y = radius * sintheta;
      result.z = 0.0;
    }

    return Matrix3.multiplyByVector(perifocalToEquatorial, result, result);
  }

  function chooseOrbit(eccentricity, tolerance) {
    //>>includeStart('debug', pragmas.debug);
    if (eccentricity < 0) {
      throw new DeveloperError("eccentricity cannot be negative.");
    }
    //>>includeEnd('debug')

    if (eccentricity <= tolerance) {
      return "Circular";
    } else if (eccentricity < 1.0 - tolerance) {
      return "Elliptical";
    } else if (eccentricity <= 1.0 + tolerance) {
      return "Parabolic";
    }
    return "Hyperbolic";
  }

  // Calculates the true anomaly given the mean anomaly and the eccentricity.
  function meanAnomalyToTrueAnomaly(meanAnomaly, eccentricity) {
    //>>includeStart('debug', pragmas.debug);
    if (eccentricity < 0.0 || eccentricity >= 1.0) {
      throw new DeveloperError("eccentricity out of range.");
    }
    //>>includeEnd('debug')

    var eccentricAnomaly = meanAnomalyToEccentricAnomaly(
      meanAnomaly,
      eccentricity
    );
    return eccentricAnomalyToTrueAnomaly(eccentricAnomaly, eccentricity);
  }

  var maxIterationCount = 50;
  var keplerEqConvergence = CesiumMath.EPSILON8;
  // Calculates the eccentric anomaly given the mean anomaly and the eccentricity.
  function meanAnomalyToEccentricAnomaly(meanAnomaly, eccentricity) {
    //>>includeStart('debug', pragmas.debug);
    if (eccentricity < 0.0 || eccentricity >= 1.0) {
      throw new DeveloperError("eccentricity out of range.");
    }
    //>>includeEnd('debug')

    var revs = Math.floor(meanAnomaly / CesiumMath.TWO_PI);

    // Find angle in current revolution
    meanAnomaly -= revs * CesiumMath.TWO_PI;

    // calculate starting value for iteration sequence
    var iterationValue =
      meanAnomaly +
      (eccentricity * Math.sin(meanAnomaly)) /
        (1.0 - Math.sin(meanAnomaly + eccentricity) + Math.sin(meanAnomaly));

    // Perform Newton-Raphson iteration on Kepler's equation
    var eccentricAnomaly = Number.MAX_VALUE;

    var count;
    for (
      count = 0;
      count < maxIterationCount &&
      Math.abs(eccentricAnomaly - iterationValue) > keplerEqConvergence;
      ++count
    ) {
      eccentricAnomaly = iterationValue;
      var NRfunction =
        eccentricAnomaly -
        eccentricity * Math.sin(eccentricAnomaly) -
        meanAnomaly;
      var dNRfunction = 1 - eccentricity * Math.cos(eccentricAnomaly);
      iterationValue = eccentricAnomaly - NRfunction / dNRfunction;
    }

    //>>includeStart('debug', pragmas.debug);
    if (count >= maxIterationCount) {
      throw new DeveloperError("Kepler equation did not converge");
      // STK Components uses a numerical method to find the eccentric anomaly in the case that Kepler's
      // equation does not converge. We don't expect that to ever be necessary for the reasonable orbits used here.
    }
    //>>includeEnd('debug')

    eccentricAnomaly = iterationValue + revs * CesiumMath.TWO_PI;
    return eccentricAnomaly;
  }

  // Calculates the true anomaly given the eccentric anomaly and the eccentricity.
  function eccentricAnomalyToTrueAnomaly(eccentricAnomaly, eccentricity) {
    //>>includeStart('debug', pragmas.debug);
    if (eccentricity < 0.0 || eccentricity >= 1.0) {
      throw new DeveloperError("eccentricity out of range.");
    }
    //>>includeEnd('debug')

    // Calculate the number of previous revolutions
    var revs = Math.floor(eccentricAnomaly / CesiumMath.TWO_PI);

    // Find angle in current revolution
    eccentricAnomaly -= revs * CesiumMath.TWO_PI;

    // Calculate true anomaly from eccentric anomaly
    var trueAnomalyX = Math.cos(eccentricAnomaly) - eccentricity;
    var trueAnomalyY =
      Math.sin(eccentricAnomaly) * Math.sqrt(1 - eccentricity * eccentricity);

    var trueAnomaly = Math.atan2(trueAnomalyY, trueAnomalyX);

    // Ensure the correct quadrant
    trueAnomaly = CesiumMath.zeroToTwoPi(trueAnomaly);
    if (eccentricAnomaly < 0) {
      trueAnomaly -= CesiumMath.TWO_PI;
    }

    // Add on previous revolutions
    trueAnomaly += revs * CesiumMath.TWO_PI;

    return trueAnomaly;
  }

  // Calculates the transformation matrix to convert from the perifocal (PQW) coordinate
  // system to inertial cartesian coordinates.
  function perifocalToCartesianMatrix(
    argumentOfPeriapsis,
    inclination,
    rightAscension,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (inclination < 0 || inclination > CesiumMath.PI) {
      throw new DeveloperError("inclination out of range");
    }
    //>>includeEnd('debug')

    var cosap = Math.cos(argumentOfPeriapsis);
    var sinap = Math.sin(argumentOfPeriapsis);

    var cosi = Math.cos(inclination);
    var sini = Math.sin(inclination);

    var cosraan = Math.cos(rightAscension);
    var sinraan = Math.sin(rightAscension);
    if (!defined(result)) {
      result = new Matrix3(
        cosraan * cosap - sinraan * sinap * cosi,
        -cosraan * sinap - sinraan * cosap * cosi,
        sinraan * sini,

        sinraan * cosap + cosraan * sinap * cosi,
        -sinraan * sinap + cosraan * cosap * cosi,
        -cosraan * sini,

        sinap * sini,
        cosap * sini,
        cosi
      );
    } else {
      result[0] = cosraan * cosap - sinraan * sinap * cosi;
      result[1] = sinraan * cosap + cosraan * sinap * cosi;
      result[2] = sinap * sini;
      result[3] = -cosraan * sinap - sinraan * cosap * cosi;
      result[4] = -sinraan * sinap + cosraan * cosap * cosi;
      result[5] = cosap * sini;
      result[6] = sinraan * sini;
      result[7] = -cosraan * sini;
      result[8] = cosi;
    }
    return result;
  }

  // From section 5.8
  var semiMajorAxis0 = 1.0000010178 * MetersPerAstronomicalUnit;
  var meanLongitude0 = 100.46645683 * RadiansPerDegree;
  var meanLongitude1 = 1295977422.83429 * RadiansPerArcSecond;

  // From table 6
  var p1u = 16002;
  var p2u = 21863;
  var p3u = 32004;
  var p4u = 10931;
  var p5u = 14529;
  var p6u = 16368;
  var p7u = 15318;
  var p8u = 32794;

  var Ca1 = 64 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca2 = -152 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca3 = 62 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca4 = -8 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca5 = 32 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca6 = -41 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca7 = 19 * 1e-7 * MetersPerAstronomicalUnit;
  var Ca8 = -11 * 1e-7 * MetersPerAstronomicalUnit;

  var Sa1 = -150 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa2 = -46 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa3 = 68 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa4 = 54 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa5 = 14 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa6 = 24 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa7 = -28 * 1e-7 * MetersPerAstronomicalUnit;
  var Sa8 = 22 * 1e-7 * MetersPerAstronomicalUnit;

  var q1u = 10;
  var q2u = 16002;
  var q3u = 21863;
  var q4u = 10931;
  var q5u = 1473;
  var q6u = 32004;
  var q7u = 4387;
  var q8u = 73;

  var Cl1 = -325 * 1e-7;
  var Cl2 = -322 * 1e-7;
  var Cl3 = -79 * 1e-7;
  var Cl4 = 232 * 1e-7;
  var Cl5 = -52 * 1e-7;
  var Cl6 = 97 * 1e-7;
  var Cl7 = 55 * 1e-7;
  var Cl8 = -41 * 1e-7;

  var Sl1 = -105 * 1e-7;
  var Sl2 = -137 * 1e-7;
  var Sl3 = 258 * 1e-7;
  var Sl4 = 35 * 1e-7;
  var Sl5 = -116 * 1e-7;
  var Sl6 = -88 * 1e-7;
  var Sl7 = -112 * 1e-7;
  var Sl8 = -80 * 1e-7;

  var scratchDate = new JulianDate(0, 0.0, TimeStandard$1.TAI);
  // Gets a point describing the motion of the Earth-Moon barycenter according to the equations described in section 6.
  function computeSimonEarthMoonBarycenter(date, result) {
    // t is thousands of years from J2000 TDB
    taiToTdb(date, scratchDate);
    var x =
      scratchDate.dayNumber -
      epoch.dayNumber +
      (scratchDate.secondsOfDay - epoch.secondsOfDay) /
        TimeConstants$1.SECONDS_PER_DAY;
    var t = x / (TimeConstants$1.DAYS_PER_JULIAN_CENTURY * 10.0);

    var u = 0.3595362 * t;
    var semimajorAxis =
      semiMajorAxis0 +
      Ca1 * Math.cos(p1u * u) +
      Sa1 * Math.sin(p1u * u) +
      Ca2 * Math.cos(p2u * u) +
      Sa2 * Math.sin(p2u * u) +
      Ca3 * Math.cos(p3u * u) +
      Sa3 * Math.sin(p3u * u) +
      Ca4 * Math.cos(p4u * u) +
      Sa4 * Math.sin(p4u * u) +
      Ca5 * Math.cos(p5u * u) +
      Sa5 * Math.sin(p5u * u) +
      Ca6 * Math.cos(p6u * u) +
      Sa6 * Math.sin(p6u * u) +
      Ca7 * Math.cos(p7u * u) +
      Sa7 * Math.sin(p7u * u) +
      Ca8 * Math.cos(p8u * u) +
      Sa8 * Math.sin(p8u * u);
    var meanLongitude =
      meanLongitude0 +
      meanLongitude1 * t +
      Cl1 * Math.cos(q1u * u) +
      Sl1 * Math.sin(q1u * u) +
      Cl2 * Math.cos(q2u * u) +
      Sl2 * Math.sin(q2u * u) +
      Cl3 * Math.cos(q3u * u) +
      Sl3 * Math.sin(q3u * u) +
      Cl4 * Math.cos(q4u * u) +
      Sl4 * Math.sin(q4u * u) +
      Cl5 * Math.cos(q5u * u) +
      Sl5 * Math.sin(q5u * u) +
      Cl6 * Math.cos(q6u * u) +
      Sl6 * Math.sin(q6u * u) +
      Cl7 * Math.cos(q7u * u) +
      Sl7 * Math.sin(q7u * u) +
      Cl8 * Math.cos(q8u * u) +
      Sl8 * Math.sin(q8u * u);

    // All constants in this part are from section 5.8
    var eccentricity = 0.0167086342 - 0.0004203654 * t;
    var longitudeOfPerigee =
      102.93734808 * RadiansPerDegree + 11612.3529 * RadiansPerArcSecond * t;
    var inclination = 469.97289 * RadiansPerArcSecond * t;
    var longitudeOfNode =
      174.87317577 * RadiansPerDegree - 8679.27034 * RadiansPerArcSecond * t;

    return elementsToCartesian(
      semimajorAxis,
      eccentricity,
      inclination,
      longitudeOfPerigee,
      longitudeOfNode,
      meanLongitude,
      result
    );
  }

  // Gets a point describing the position of the moon according to the equations described in section 4.
  function computeSimonMoon(date, result) {
    taiToTdb(date, scratchDate);
    var x =
      scratchDate.dayNumber -
      epoch.dayNumber +
      (scratchDate.secondsOfDay - epoch.secondsOfDay) /
        TimeConstants$1.SECONDS_PER_DAY;
    var t = x / TimeConstants$1.DAYS_PER_JULIAN_CENTURY;
    var t2 = t * t;
    var t3 = t2 * t;
    var t4 = t3 * t;

    // Terms from section 3.4 (b.1)
    var semimajorAxis = 383397.7725 + 0.004 * t;
    var eccentricity = 0.055545526 - 0.000000016 * t;
    var inclinationConstant = 5.15668983 * RadiansPerDegree;
    var inclinationSecPart =
      -0.00008 * t + 0.02966 * t2 - 0.000042 * t3 - 0.00000013 * t4;
    var longitudeOfPerigeeConstant = 83.35324312 * RadiansPerDegree;
    var longitudeOfPerigeeSecPart =
      14643420.2669 * t - 38.2702 * t2 - 0.045047 * t3 + 0.00021301 * t4;
    var longitudeOfNodeConstant = 125.04455501 * RadiansPerDegree;
    var longitudeOfNodeSecPart =
      -6967919.3631 * t + 6.3602 * t2 + 0.007625 * t3 - 0.00003586 * t4;
    var meanLongitudeConstant = 218.31664563 * RadiansPerDegree;
    var meanLongitudeSecPart =
      1732559343.4847 * t - 6.391 * t2 + 0.006588 * t3 - 0.00003169 * t4;

    // Delaunay arguments from section 3.5 b
    var D =
      297.85019547 * RadiansPerDegree +
      RadiansPerArcSecond *
        (1602961601.209 * t - 6.3706 * t2 + 0.006593 * t3 - 0.00003169 * t4);
    var F =
      93.27209062 * RadiansPerDegree +
      RadiansPerArcSecond *
        (1739527262.8478 * t - 12.7512 * t2 - 0.001037 * t3 + 0.00000417 * t4);
    var l =
      134.96340251 * RadiansPerDegree +
      RadiansPerArcSecond *
        (1717915923.2178 * t + 31.8792 * t2 + 0.051635 * t3 - 0.0002447 * t4);
    var lprime =
      357.52910918 * RadiansPerDegree +
      RadiansPerArcSecond *
        (129596581.0481 * t - 0.5532 * t2 + 0.000136 * t3 - 0.00001149 * t4);
    var psi =
      310.17137918 * RadiansPerDegree -
      RadiansPerArcSecond *
        (6967051.436 * t + 6.2068 * t2 + 0.007618 * t3 - 0.00003219 * t4);

    // Add terms from Table 4
    var twoD = 2.0 * D;
    var fourD = 4.0 * D;
    var sixD = 6.0 * D;
    var twol = 2.0 * l;
    var threel = 3.0 * l;
    var fourl = 4.0 * l;
    var twoF = 2.0 * F;
    semimajorAxis +=
      3400.4 * Math.cos(twoD) -
      635.6 * Math.cos(twoD - l) -
      235.6 * Math.cos(l) +
      218.1 * Math.cos(twoD - lprime) +
      181.0 * Math.cos(twoD + l);
    eccentricity +=
      0.014216 * Math.cos(twoD - l) +
      0.008551 * Math.cos(twoD - twol) -
      0.001383 * Math.cos(l) +
      0.001356 * Math.cos(twoD + l) -
      0.001147 * Math.cos(fourD - threel) -
      0.000914 * Math.cos(fourD - twol) +
      0.000869 * Math.cos(twoD - lprime - l) -
      0.000627 * Math.cos(twoD) -
      0.000394 * Math.cos(fourD - fourl) +
      0.000282 * Math.cos(twoD - lprime - twol) -
      0.000279 * Math.cos(D - l) -
      0.000236 * Math.cos(twol) +
      0.000231 * Math.cos(fourD) +
      0.000229 * Math.cos(sixD - fourl) -
      0.000201 * Math.cos(twol - twoF);
    inclinationSecPart +=
      486.26 * Math.cos(twoD - twoF) -
      40.13 * Math.cos(twoD) +
      37.51 * Math.cos(twoF) +
      25.73 * Math.cos(twol - twoF) +
      19.97 * Math.cos(twoD - lprime - twoF);
    longitudeOfPerigeeSecPart +=
      -55609 * Math.sin(twoD - l) -
      34711 * Math.sin(twoD - twol) -
      9792 * Math.sin(l) +
      9385 * Math.sin(fourD - threel) +
      7505 * Math.sin(fourD - twol) +
      5318 * Math.sin(twoD + l) +
      3484 * Math.sin(fourD - fourl) -
      3417 * Math.sin(twoD - lprime - l) -
      2530 * Math.sin(sixD - fourl) -
      2376 * Math.sin(twoD) -
      2075 * Math.sin(twoD - threel) -
      1883 * Math.sin(twol) -
      1736 * Math.sin(sixD - 5.0 * l) +
      1626 * Math.sin(lprime) -
      1370 * Math.sin(sixD - threel);
    longitudeOfNodeSecPart +=
      -5392 * Math.sin(twoD - twoF) -
      540 * Math.sin(lprime) -
      441 * Math.sin(twoD) +
      423 * Math.sin(twoF) -
      288 * Math.sin(twol - twoF);
    meanLongitudeSecPart +=
      -3332.9 * Math.sin(twoD) +
      1197.4 * Math.sin(twoD - l) -
      662.5 * Math.sin(lprime) +
      396.3 * Math.sin(l) -
      218.0 * Math.sin(twoD - lprime);

    // Add terms from Table 5
    var twoPsi = 2.0 * psi;
    var threePsi = 3.0 * psi;
    inclinationSecPart +=
      46.997 * Math.cos(psi) * t -
      0.614 * Math.cos(twoD - twoF + psi) * t +
      0.614 * Math.cos(twoD - twoF - psi) * t -
      0.0297 * Math.cos(twoPsi) * t2 -
      0.0335 * Math.cos(psi) * t2 +
      0.0012 * Math.cos(twoD - twoF + twoPsi) * t2 -
      0.00016 * Math.cos(psi) * t3 +
      0.00004 * Math.cos(threePsi) * t3 +
      0.00004 * Math.cos(twoPsi) * t3;
    var perigeeAndMean =
      2.116 * Math.sin(psi) * t -
      0.111 * Math.sin(twoD - twoF - psi) * t -
      0.0015 * Math.sin(psi) * t2;
    longitudeOfPerigeeSecPart += perigeeAndMean;
    meanLongitudeSecPart += perigeeAndMean;
    longitudeOfNodeSecPart +=
      -520.77 * Math.sin(psi) * t +
      13.66 * Math.sin(twoD - twoF + psi) * t +
      1.12 * Math.sin(twoD - psi) * t -
      1.06 * Math.sin(twoF - psi) * t +
      0.66 * Math.sin(twoPsi) * t2 +
      0.371 * Math.sin(psi) * t2 -
      0.035 * Math.sin(twoD - twoF + twoPsi) * t2 -
      0.015 * Math.sin(twoD - twoF + psi) * t2 +
      0.0014 * Math.sin(psi) * t3 -
      0.0011 * Math.sin(threePsi) * t3 -
      0.0009 * Math.sin(twoPsi) * t3;

    // Add constants and convert units
    semimajorAxis *= MetersPerKilometer;
    var inclination =
      inclinationConstant + inclinationSecPart * RadiansPerArcSecond;
    var longitudeOfPerigee =
      longitudeOfPerigeeConstant +
      longitudeOfPerigeeSecPart * RadiansPerArcSecond;
    var meanLongitude =
      meanLongitudeConstant + meanLongitudeSecPart * RadiansPerArcSecond;
    var longitudeOfNode =
      longitudeOfNodeConstant + longitudeOfNodeSecPart * RadiansPerArcSecond;

    return elementsToCartesian(
      semimajorAxis,
      eccentricity,
      inclination,
      longitudeOfPerigee,
      longitudeOfNode,
      meanLongitude,
      result
    );
  }

  // Gets a point describing the motion of the Earth.  This point uses the Moon point and
  // the 1992 mu value (ratio between Moon and Earth masses) in Table 2 of the paper in order
  // to determine the position of the Earth relative to the Earth-Moon barycenter.
  var moonEarthMassRatio = 0.012300034; // From 1992 mu value in Table 2
  var factor = (moonEarthMassRatio / (moonEarthMassRatio + 1.0)) * -1;
  function computeSimonEarth(date, result) {
    result = computeSimonMoon(date, result);
    return Cartesian3.multiplyByScalar(result, factor, result);
  }

  // Values for the <code>axesTransformation</code> needed for the rotation were found using the STK Components
  // GreographicTransformer on the position of the sun center of mass point and the earth J2000 frame.

  var axesTransformation = new Matrix3(
    1.0000000000000002,
    5.619723173785822e-16,
    4.690511510146299e-19,
    -5.154129427414611e-16,
    0.9174820620691819,
    -0.39777715593191376,
    -2.23970096136568e-16,
    0.39777715593191376,
    0.9174820620691819
  );
  var translation$1 = new Cartesian3();
  /**
   * Computes the position of the Sun in the Earth-centered inertial frame
   *
   * @param {JulianDate} [julianDate] The time at which to compute the Sun's position, if not provided the current system time is used.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} Calculated sun position
   */
  Simon1994PlanetaryPositions.computeSunPositionInEarthInertialFrame = function (
    julianDate,
    result
  ) {
    if (!defined(julianDate)) {
      julianDate = JulianDate.now();
    }

    if (!defined(result)) {
      result = new Cartesian3();
    }

    //first forward transformation
    translation$1 = computeSimonEarthMoonBarycenter(julianDate, translation$1);
    result = Cartesian3.negate(translation$1, result);

    //second forward transformation
    computeSimonEarth(julianDate, translation$1);

    Cartesian3.subtract(result, translation$1, result);
    Matrix3.multiplyByVector(axesTransformation, result, result);

    return result;
  };

  /**
   * Computes the position of the Moon in the Earth-centered inertial frame
   *
   * @param {JulianDate} [julianDate] The time at which to compute the Sun's position, if not provided the current system time is used.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} Calculated moon position
   */
  Simon1994PlanetaryPositions.computeMoonPositionInEarthInertialFrame = function (
    julianDate,
    result
  ) {
    if (!defined(julianDate)) {
      julianDate = JulianDate.now();
    }

    result = computeSimonMoon(julianDate, result);
    Matrix3.multiplyByVector(axesTransformation, result, result);

    return result;
  };

  function interpolateColors$1(p0, p1, color0, color1, minDistance, array, offset) {
    var numPoints = PolylinePipeline.numberOfPoints(p0, p1, minDistance);
    var i;

    var r0 = color0.red;
    var g0 = color0.green;
    var b0 = color0.blue;
    var a0 = color0.alpha;

    var r1 = color1.red;
    var g1 = color1.green;
    var b1 = color1.blue;
    var a1 = color1.alpha;

    if (Color.equals(color0, color1)) {
      for (i = 0; i < numPoints; i++) {
        array[offset++] = Color.floatToByte(r0);
        array[offset++] = Color.floatToByte(g0);
        array[offset++] = Color.floatToByte(b0);
        array[offset++] = Color.floatToByte(a0);
      }
      return offset;
    }

    var redPerVertex = (r1 - r0) / numPoints;
    var greenPerVertex = (g1 - g0) / numPoints;
    var bluePerVertex = (b1 - b0) / numPoints;
    var alphaPerVertex = (a1 - a0) / numPoints;

    var index = offset;
    for (i = 0; i < numPoints; i++) {
      array[index++] = Color.floatToByte(r0 + i * redPerVertex);
      array[index++] = Color.floatToByte(g0 + i * greenPerVertex);
      array[index++] = Color.floatToByte(b0 + i * bluePerVertex);
      array[index++] = Color.floatToByte(a0 + i * alphaPerVertex);
    }

    return index;
  }

  /**
   * A description of a polyline modeled as a line strip; the first two positions define a line segment,
   * and each additional position defines a line segment from the previous position.
   *
   * @alias SimplePolylineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of {@link Cartesian3} defining the positions in the polyline as a line strip.
   * @param {Color[]} [options.colors] An Array of {@link Color} defining the per vertex or per segment colors.
   * @param {Boolean} [options.colorsPerVertex=false] A boolean that determines whether the colors will be flat across each segment of the line or interpolated across the vertices.
   * @param {ArcType} [options.arcType=ArcType.GEODESIC] The type of line the polyline segments must follow.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude if options.arcType is not ArcType.NONE. Determines the number of positions in the buffer.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid to be used as a reference.
   *
   * @exception {DeveloperError} At least two positions are required.
   * @exception {DeveloperError} colors has an invalid length.
   *
   * @see SimplePolylineGeometry#createGeometry
   *
   * @example
   * // A polyline with two connected line segments
   * var polyline = new Cesium.SimplePolylineGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     0.0, 0.0,
   *     5.0, 0.0,
   *     5.0, 5.0
   *   ])
   * });
   * var geometry = Cesium.SimplePolylineGeometry.createGeometry(polyline);
   */
  function SimplePolylineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;
    var colors = options.colors;
    var colorsPerVertex = defaultValue(options.colorsPerVertex, false);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions) || positions.length < 2) {
      throw new DeveloperError("At least two positions are required.");
    }
    if (
      defined(colors) &&
      ((colorsPerVertex && colors.length < positions.length) ||
        (!colorsPerVertex && colors.length < positions.length - 1))
    ) {
      throw new DeveloperError("colors has an invalid length.");
    }
    //>>includeEnd('debug');

    this._positions = positions;
    this._colors = colors;
    this._colorsPerVertex = colorsPerVertex;

    this._arcType = defaultValue(options.arcType, ArcType$1.GEODESIC);
    this._granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    this._workerName = "createSimplePolylineGeometry";

    var numComponents = 1 + positions.length * Cartesian3.packedLength;
    numComponents += defined(colors) ? 1 + colors.length * Color.packedLength : 1;

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength = numComponents + Ellipsoid.packedLength + 3;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {SimplePolylineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  SimplePolylineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    var colors = value._colors;
    length = defined(colors) ? colors.length : 0.0;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Color.packedLength) {
      Color.pack(colors[i], array, startingIndex);
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex++] = value._colorsPerVertex ? 1.0 : 0.0;
    array[startingIndex++] = value._arcType;
    array[startingIndex] = value._granularity;

    return array;
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {SimplePolylineGeometry} [result] The object into which to store the result.
   * @returns {SimplePolylineGeometry} The modified result parameter or a new SimplePolylineGeometry instance if one was not provided.
   */
  SimplePolylineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    length = array[startingIndex++];
    var colors = length > 0 ? new Array(length) : undefined;

    for (i = 0; i < length; ++i, startingIndex += Color.packedLength) {
      colors[i] = Color.unpack(array, startingIndex);
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    var colorsPerVertex = array[startingIndex++] === 1.0;
    var arcType = array[startingIndex++];
    var granularity = array[startingIndex];

    if (!defined(result)) {
      return new SimplePolylineGeometry({
        positions: positions,
        colors: colors,
        ellipsoid: ellipsoid,
        colorsPerVertex: colorsPerVertex,
        arcType: arcType,
        granularity: granularity,
      });
    }

    result._positions = positions;
    result._colors = colors;
    result._ellipsoid = ellipsoid;
    result._colorsPerVertex = colorsPerVertex;
    result._arcType = arcType;
    result._granularity = granularity;

    return result;
  };

  var scratchArray1 = new Array(2);
  var scratchArray2 = new Array(2);
  var generateArcOptionsScratch = {
    positions: scratchArray1,
    height: scratchArray2,
    ellipsoid: undefined,
    minDistance: undefined,
    granularity: undefined,
  };

  /**
   * Computes the geometric representation of a simple polyline, including its vertices, indices, and a bounding sphere.
   *
   * @param {SimplePolylineGeometry} simplePolylineGeometry A description of the polyline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  SimplePolylineGeometry.createGeometry = function (simplePolylineGeometry) {
    var positions = simplePolylineGeometry._positions;
    var colors = simplePolylineGeometry._colors;
    var colorsPerVertex = simplePolylineGeometry._colorsPerVertex;
    var arcType = simplePolylineGeometry._arcType;
    var granularity = simplePolylineGeometry._granularity;
    var ellipsoid = simplePolylineGeometry._ellipsoid;

    var minDistance = CesiumMath.chordLength(
      granularity,
      ellipsoid.maximumRadius
    );
    var perSegmentColors = defined(colors) && !colorsPerVertex;

    var i;
    var length = positions.length;

    var positionValues;
    var numberOfPositions;
    var colorValues;
    var color;
    var offset = 0;

    if (arcType === ArcType$1.GEODESIC || arcType === ArcType$1.RHUMB) {
      var subdivisionSize;
      var numberOfPointsFunction;
      var generateArcFunction;
      if (arcType === ArcType$1.GEODESIC) {
        subdivisionSize = CesiumMath.chordLength(
          granularity,
          ellipsoid.maximumRadius
        );
        numberOfPointsFunction = PolylinePipeline.numberOfPoints;
        generateArcFunction = PolylinePipeline.generateArc;
      } else {
        subdivisionSize = granularity;
        numberOfPointsFunction = PolylinePipeline.numberOfPointsRhumbLine;
        generateArcFunction = PolylinePipeline.generateRhumbArc;
      }

      var heights = PolylinePipeline.extractHeights(positions, ellipsoid);

      var generateArcOptions = generateArcOptionsScratch;
      if (arcType === ArcType$1.GEODESIC) {
        generateArcOptions.minDistance = minDistance;
      } else {
        generateArcOptions.granularity = granularity;
      }
      generateArcOptions.ellipsoid = ellipsoid;

      if (perSegmentColors) {
        var positionCount = 0;
        for (i = 0; i < length - 1; i++) {
          positionCount +=
            numberOfPointsFunction(
              positions[i],
              positions[i + 1],
              subdivisionSize
            ) + 1;
        }

        positionValues = new Float64Array(positionCount * 3);
        colorValues = new Uint8Array(positionCount * 4);

        generateArcOptions.positions = scratchArray1;
        generateArcOptions.height = scratchArray2;

        var ci = 0;
        for (i = 0; i < length - 1; ++i) {
          scratchArray1[0] = positions[i];
          scratchArray1[1] = positions[i + 1];

          scratchArray2[0] = heights[i];
          scratchArray2[1] = heights[i + 1];

          var pos = generateArcFunction(generateArcOptions);

          if (defined(colors)) {
            var segLen = pos.length / 3;
            color = colors[i];
            for (var k = 0; k < segLen; ++k) {
              colorValues[ci++] = Color.floatToByte(color.red);
              colorValues[ci++] = Color.floatToByte(color.green);
              colorValues[ci++] = Color.floatToByte(color.blue);
              colorValues[ci++] = Color.floatToByte(color.alpha);
            }
          }

          positionValues.set(pos, offset);
          offset += pos.length;
        }
      } else {
        generateArcOptions.positions = positions;
        generateArcOptions.height = heights;
        positionValues = new Float64Array(
          generateArcFunction(generateArcOptions)
        );

        if (defined(colors)) {
          colorValues = new Uint8Array((positionValues.length / 3) * 4);

          for (i = 0; i < length - 1; ++i) {
            var p0 = positions[i];
            var p1 = positions[i + 1];
            var c0 = colors[i];
            var c1 = colors[i + 1];
            offset = interpolateColors$1(
              p0,
              p1,
              c0,
              c1,
              minDistance,
              colorValues,
              offset
            );
          }

          var lastColor = colors[length - 1];
          colorValues[offset++] = Color.floatToByte(lastColor.red);
          colorValues[offset++] = Color.floatToByte(lastColor.green);
          colorValues[offset++] = Color.floatToByte(lastColor.blue);
          colorValues[offset++] = Color.floatToByte(lastColor.alpha);
        }
      }
    } else {
      numberOfPositions = perSegmentColors ? length * 2 - 2 : length;
      positionValues = new Float64Array(numberOfPositions * 3);
      colorValues = defined(colors)
        ? new Uint8Array(numberOfPositions * 4)
        : undefined;

      var positionIndex = 0;
      var colorIndex = 0;

      for (i = 0; i < length; ++i) {
        var p = positions[i];

        if (perSegmentColors && i > 0) {
          Cartesian3.pack(p, positionValues, positionIndex);
          positionIndex += 3;

          color = colors[i - 1];
          colorValues[colorIndex++] = Color.floatToByte(color.red);
          colorValues[colorIndex++] = Color.floatToByte(color.green);
          colorValues[colorIndex++] = Color.floatToByte(color.blue);
          colorValues[colorIndex++] = Color.floatToByte(color.alpha);
        }

        if (perSegmentColors && i === length - 1) {
          break;
        }

        Cartesian3.pack(p, positionValues, positionIndex);
        positionIndex += 3;

        if (defined(colors)) {
          color = colors[i];
          colorValues[colorIndex++] = Color.floatToByte(color.red);
          colorValues[colorIndex++] = Color.floatToByte(color.green);
          colorValues[colorIndex++] = Color.floatToByte(color.blue);
          colorValues[colorIndex++] = Color.floatToByte(color.alpha);
        }
      }
    }

    var attributes = new GeometryAttributes();
    attributes.position = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.DOUBLE,
      componentsPerAttribute: 3,
      values: positionValues,
    });

    if (defined(colors)) {
      attributes.color = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 4,
        values: colorValues,
        normalize: true,
      });
    }

    numberOfPositions = positionValues.length / 3;
    var numberOfIndices = (numberOfPositions - 1) * 2;
    var indices = IndexDatatype$1.createTypedArray(
      numberOfPositions,
      numberOfIndices
    );

    var index = 0;
    for (i = 0; i < numberOfPositions - 1; ++i) {
      indices[index++] = i;
      indices[index++] = i + 1;
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: BoundingSphere.fromPoints(positions),
    });
  };

  /**
   * A description of a sphere centered at the origin.
   *
   * @alias SphereGeometry
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Number} [options.radius=1.0] The radius of the sphere.
   * @param {Number} [options.stackPartitions=64] The number of times to partition the ellipsoid into stacks.
   * @param {Number} [options.slicePartitions=64] The number of times to partition the ellipsoid into radial slices.
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @exception {DeveloperError} options.slicePartitions cannot be less than three.
   * @exception {DeveloperError} options.stackPartitions cannot be less than three.
   *
   * @see SphereGeometry#createGeometry
   *
   * @example
   * var sphere = new Cesium.SphereGeometry({
   *   radius : 100.0,
   *   vertexFormat : Cesium.VertexFormat.POSITION_ONLY
   * });
   * var geometry = Cesium.SphereGeometry.createGeometry(sphere);
   */
  function SphereGeometry(options) {
    var radius = defaultValue(options.radius, 1.0);
    var radii = new Cartesian3(radius, radius, radius);
    var ellipsoidOptions = {
      radii: radii,
      stackPartitions: options.stackPartitions,
      slicePartitions: options.slicePartitions,
      vertexFormat: options.vertexFormat,
    };

    this._ellipsoidGeometry = new EllipsoidGeometry(ellipsoidOptions);
    this._workerName = "createSphereGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  SphereGeometry.packedLength = EllipsoidGeometry.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {SphereGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  SphereGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    //>>includeEnd('debug');

    return EllipsoidGeometry.pack(value._ellipsoidGeometry, array, startingIndex);
  };

  var scratchEllipsoidGeometry = new EllipsoidGeometry();
  var scratchOptions$k = {
    radius: undefined,
    radii: new Cartesian3(),
    vertexFormat: new VertexFormat(),
    stackPartitions: undefined,
    slicePartitions: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {SphereGeometry} [result] The object into which to store the result.
   * @returns {SphereGeometry} The modified result parameter or a new SphereGeometry instance if one was not provided.
   */
  SphereGeometry.unpack = function (array, startingIndex, result) {
    var ellipsoidGeometry = EllipsoidGeometry.unpack(
      array,
      startingIndex,
      scratchEllipsoidGeometry
    );
    scratchOptions$k.vertexFormat = VertexFormat.clone(
      ellipsoidGeometry._vertexFormat,
      scratchOptions$k.vertexFormat
    );
    scratchOptions$k.stackPartitions = ellipsoidGeometry._stackPartitions;
    scratchOptions$k.slicePartitions = ellipsoidGeometry._slicePartitions;

    if (!defined(result)) {
      scratchOptions$k.radius = ellipsoidGeometry._radii.x;
      return new SphereGeometry(scratchOptions$k);
    }

    Cartesian3.clone(ellipsoidGeometry._radii, scratchOptions$k.radii);
    result._ellipsoidGeometry = new EllipsoidGeometry(scratchOptions$k);
    return result;
  };

  /**
   * Computes the geometric representation of a sphere, including its vertices, indices, and a bounding sphere.
   *
   * @param {SphereGeometry} sphereGeometry A description of the sphere.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  SphereGeometry.createGeometry = function (sphereGeometry) {
    return EllipsoidGeometry.createGeometry(sphereGeometry._ellipsoidGeometry);
  };

  /**
   * A description of the outline of a sphere.
   *
   * @alias SphereOutlineGeometry
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Number} [options.radius=1.0] The radius of the sphere.
   * @param {Number} [options.stackPartitions=10] The count of stacks for the sphere (1 greater than the number of parallel lines).
   * @param {Number} [options.slicePartitions=8] The count of slices for the sphere (Equal to the number of radial lines).
   * @param {Number} [options.subdivisions=200] The number of points per line, determining the granularity of the curvature .
   *
   * @exception {DeveloperError} options.stackPartitions must be greater than or equal to one.
   * @exception {DeveloperError} options.slicePartitions must be greater than or equal to zero.
   * @exception {DeveloperError} options.subdivisions must be greater than or equal to zero.
   *
   * @example
   * var sphere = new Cesium.SphereOutlineGeometry({
   *   radius : 100.0,
   *   stackPartitions : 6,
   *   slicePartitions: 5
   * });
   * var geometry = Cesium.SphereOutlineGeometry.createGeometry(sphere);
   */
  function SphereOutlineGeometry(options) {
    var radius = defaultValue(options.radius, 1.0);
    var radii = new Cartesian3(radius, radius, radius);
    var ellipsoidOptions = {
      radii: radii,
      stackPartitions: options.stackPartitions,
      slicePartitions: options.slicePartitions,
      subdivisions: options.subdivisions,
    };

    this._ellipsoidGeometry = new EllipsoidOutlineGeometry(ellipsoidOptions);
    this._workerName = "createSphereOutlineGeometry";
  }

  /**
   * The number of elements used to pack the object into an array.
   * @type {Number}
   */
  SphereOutlineGeometry.packedLength = EllipsoidOutlineGeometry.packedLength;

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {SphereOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  SphereOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("value", value);
    //>>includeEnd('debug');

    return EllipsoidOutlineGeometry.pack(
      value._ellipsoidGeometry,
      array,
      startingIndex
    );
  };

  var scratchEllipsoidGeometry$1 = new EllipsoidOutlineGeometry();
  var scratchOptions$l = {
    radius: undefined,
    radii: new Cartesian3(),
    stackPartitions: undefined,
    slicePartitions: undefined,
    subdivisions: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {SphereOutlineGeometry} [result] The object into which to store the result.
   * @returns {SphereOutlineGeometry} The modified result parameter or a new SphereOutlineGeometry instance if one was not provided.
   */
  SphereOutlineGeometry.unpack = function (array, startingIndex, result) {
    var ellipsoidGeometry = EllipsoidOutlineGeometry.unpack(
      array,
      startingIndex,
      scratchEllipsoidGeometry$1
    );
    scratchOptions$l.stackPartitions = ellipsoidGeometry._stackPartitions;
    scratchOptions$l.slicePartitions = ellipsoidGeometry._slicePartitions;
    scratchOptions$l.subdivisions = ellipsoidGeometry._subdivisions;

    if (!defined(result)) {
      scratchOptions$l.radius = ellipsoidGeometry._radii.x;
      return new SphereOutlineGeometry(scratchOptions$l);
    }

    Cartesian3.clone(ellipsoidGeometry._radii, scratchOptions$l.radii);
    result._ellipsoidGeometry = new EllipsoidOutlineGeometry(scratchOptions$l);
    return result;
  };

  /**
   * Computes the geometric representation of an outline of a sphere, including its vertices, indices, and a bounding sphere.
   *
   * @param {SphereOutlineGeometry} sphereGeometry A description of the sphere outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  SphereOutlineGeometry.createGeometry = function (sphereGeometry) {
    return EllipsoidOutlineGeometry.createGeometry(
      sphereGeometry._ellipsoidGeometry
    );
  };

  /**
   * A set of curvilinear 3-dimensional coordinates.
   *
   * @alias Spherical
   * @constructor
   *
   * @param {Number} [clock=0.0] The angular coordinate lying in the xy-plane measured from the positive x-axis and toward the positive y-axis.
   * @param {Number} [cone=0.0] The angular coordinate measured from the positive z-axis and toward the negative z-axis.
   * @param {Number} [magnitude=1.0] The linear coordinate measured from the origin.
   */
  function Spherical(clock, cone, magnitude) {
    /**
     * The clock component.
     * @type {Number}
     * @default 0.0
     */
    this.clock = defaultValue(clock, 0.0);
    /**
     * The cone component.
     * @type {Number}
     * @default 0.0
     */
    this.cone = defaultValue(cone, 0.0);
    /**
     * The magnitude component.
     * @type {Number}
     * @default 1.0
     */
    this.magnitude = defaultValue(magnitude, 1.0);
  }

  /**
   * Converts the provided Cartesian3 into Spherical coordinates.
   *
   * @param {Cartesian3} cartesian3 The Cartesian3 to be converted to Spherical.
   * @param {Spherical} [result] The object in which the result will be stored, if undefined a new instance will be created.
   * @returns {Spherical} The modified result parameter, or a new instance if one was not provided.
   */
  Spherical.fromCartesian3 = function (cartesian3, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("cartesian3", cartesian3);
    //>>includeEnd('debug');

    var x = cartesian3.x;
    var y = cartesian3.y;
    var z = cartesian3.z;
    var radialSquared = x * x + y * y;

    if (!defined(result)) {
      result = new Spherical();
    }

    result.clock = Math.atan2(y, x);
    result.cone = Math.atan2(Math.sqrt(radialSquared), z);
    result.magnitude = Math.sqrt(radialSquared + z * z);
    return result;
  };

  /**
   * Creates a duplicate of a Spherical.
   *
   * @param {Spherical} spherical The spherical to clone.
   * @param {Spherical} [result] The object to store the result into, if undefined a new instance will be created.
   * @returns {Spherical} The modified result parameter or a new instance if result was undefined. (Returns undefined if spherical is undefined)
   */
  Spherical.clone = function (spherical, result) {
    if (!defined(spherical)) {
      return undefined;
    }

    if (!defined(result)) {
      return new Spherical(spherical.clock, spherical.cone, spherical.magnitude);
    }

    result.clock = spherical.clock;
    result.cone = spherical.cone;
    result.magnitude = spherical.magnitude;
    return result;
  };

  /**
   * Computes the normalized version of the provided spherical.
   *
   * @param {Spherical} spherical The spherical to be normalized.
   * @param {Spherical} [result] The object to store the result into, if undefined a new instance will be created.
   * @returns {Spherical} The modified result parameter or a new instance if result was undefined.
   */
  Spherical.normalize = function (spherical, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("spherical", spherical);
    //>>includeEnd('debug');

    if (!defined(result)) {
      return new Spherical(spherical.clock, spherical.cone, 1.0);
    }

    result.clock = spherical.clock;
    result.cone = spherical.cone;
    result.magnitude = 1.0;
    return result;
  };

  /**
   * Returns true if the first spherical is equal to the second spherical, false otherwise.
   *
   * @param {Spherical} left The first Spherical to be compared.
   * @param {Spherical} right The second Spherical to be compared.
   * @returns {Boolean} true if the first spherical is equal to the second spherical, false otherwise.
   */
  Spherical.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left.clock === right.clock &&
        left.cone === right.cone &&
        left.magnitude === right.magnitude)
    );
  };

  /**
   * Returns true if the first spherical is within the provided epsilon of the second spherical, false otherwise.
   *
   * @param {Spherical} left The first Spherical to be compared.
   * @param {Spherical} right The second Spherical to be compared.
   * @param {Number} [epsilon=0.0] The epsilon to compare against.
   * @returns {Boolean} true if the first spherical is within the provided epsilon of the second spherical, false otherwise.
   */
  Spherical.equalsEpsilon = function (left, right, epsilon) {
    epsilon = defaultValue(epsilon, 0.0);
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        Math.abs(left.clock - right.clock) <= epsilon &&
        Math.abs(left.cone - right.cone) <= epsilon &&
        Math.abs(left.magnitude - right.magnitude) <= epsilon)
    );
  };

  /**
   * Returns true if this spherical is equal to the provided spherical, false otherwise.
   *
   * @param {Spherical} other The Spherical to be compared.
   * @returns {Boolean} true if this spherical is equal to the provided spherical, false otherwise.
   */
  Spherical.prototype.equals = function (other) {
    return Spherical.equals(this, other);
  };

  /**
   * Creates a duplicate of this Spherical.
   *
   * @param {Spherical} [result] The object to store the result into, if undefined a new instance will be created.
   * @returns {Spherical} The modified result parameter or a new instance if result was undefined.
   */
  Spherical.prototype.clone = function (result) {
    return Spherical.clone(this, result);
  };

  /**
   * Returns true if this spherical is within the provided epsilon of the provided spherical, false otherwise.
   *
   * @param {Spherical} other The Spherical to be compared.
   * @param {Number} epsilon The epsilon to compare against.
   * @returns {Boolean} true if this spherical is within the provided epsilon of the provided spherical, false otherwise.
   */
  Spherical.prototype.equalsEpsilon = function (other, epsilon) {
    return Spherical.equalsEpsilon(this, other, epsilon);
  };

  /**
   * Returns a string representing this instance in the format (clock, cone, magnitude).
   *
   * @returns {String} A string representing this instance.
   */
  Spherical.prototype.toString = function () {
    return "(" + this.clock + ", " + this.cone + ", " + this.magnitude + ")";
  };

  /**
   * Terrain data for a single tile.  This type describes an
   * interface and is not intended to be instantiated directly.
   *
   * @alias TerrainData
   * @constructor
   *
   * @see HeightmapTerrainData
   * @see QuantizedMeshTerrainData
   * @see GoogleEarthEnterpriseTerrainData
   */
  function TerrainData() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(TerrainData.prototype, {
    /**
     * An array of credits for this tile.
     * @memberof TerrainData.prototype
     * @type {Credit[]}
     */
    credits: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * The water mask included in this terrain data, if any.  A water mask is a rectangular
     * Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land.
     * Values in between 0 and 255 are allowed as well to smoothly blend between land and water.
     * @memberof TerrainData.prototype
     * @type {Uint8Array|HTMLImageElement|HTMLCanvasElement}
     */
    waterMask: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Computes the terrain height at a specified longitude and latitude.
   * @function
   *
   * @param {Rectangle} rectangle The rectangle covered by this terrain data.
   * @param {Number} longitude The longitude in radians.
   * @param {Number} latitude The latitude in radians.
   * @returns {Number} The terrain height at the specified position.  If the position
   *          is outside the rectangle, this method will extrapolate the height, which is likely to be wildly
   *          incorrect for positions far outside the rectangle.
   */
  TerrainData.prototype.interpolateHeight =
    DeveloperError.throwInstantiationError;

  /**
   * Determines if a given child tile is available, based on the
   * {@link TerrainData#childTileMask}.  The given child tile coordinates are assumed
   * to be one of the four children of this tile.  If non-child tile coordinates are
   * given, the availability of the southeast child tile is returned.
   * @function
   *
   * @param {Number} thisX The tile X coordinate of this (the parent) tile.
   * @param {Number} thisY The tile Y coordinate of this (the parent) tile.
   * @param {Number} childX The tile X coordinate of the child tile to check for availability.
   * @param {Number} childY The tile Y coordinate of the child tile to check for availability.
   * @returns {Boolean} True if the child tile is available; otherwise, false.
   */
  TerrainData.prototype.isChildAvailable = DeveloperError.throwInstantiationError;

  /**
   * Creates a {@link TerrainMesh} from this terrain data.
   * @function
   *
   * @private
   *
   * @param {TilingScheme} tilingScheme The tiling scheme to which this tile belongs.
   * @param {Number} x The X coordinate of the tile for which to create the terrain data.
   * @param {Number} y The Y coordinate of the tile for which to create the terrain data.
   * @param {Number} level The level of the tile for which to create the terrain data.
   * @returns {Promise.<TerrainMesh>|undefined} A promise for the terrain mesh, or undefined if too many
   *          asynchronous mesh creations are already in progress and the operation should
   *          be retried later.
   */
  TerrainData.prototype.createMesh = DeveloperError.throwInstantiationError;

  /**
   * Upsamples this terrain data for use by a descendant tile.
   * @function
   *
   * @param {TilingScheme} tilingScheme The tiling scheme of this terrain data.
   * @param {Number} thisX The X coordinate of this tile in the tiling scheme.
   * @param {Number} thisY The Y coordinate of this tile in the tiling scheme.
   * @param {Number} thisLevel The level of this tile in the tiling scheme.
   * @param {Number} descendantX The X coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantY The Y coordinate within the tiling scheme of the descendant tile for which we are upsampling.
   * @param {Number} descendantLevel The level within the tiling scheme of the descendant tile for which we are upsampling.
   * @returns {Promise.<TerrainData>|undefined} A promise for upsampled terrain data for the descendant tile,
   *          or undefined if too many asynchronous upsample operations are in progress and the request has been
   *          deferred.
   */
  TerrainData.prototype.upsample = DeveloperError.throwInstantiationError;

  /**
   * Gets a value indicating whether or not this terrain data was created by upsampling lower resolution
   * terrain data.  If this value is false, the data was obtained from some other source, such
   * as by downloading it from a remote server.  This method should return true for instances
   * returned from a call to {@link TerrainData#upsample}.
   * @function
   *
   * @returns {Boolean} True if this instance was created by upsampling; otherwise, false.
   */
  TerrainData.prototype.wasCreatedByUpsampling =
    DeveloperError.throwInstantiationError;

  /**
   * @private
   */
  var TileEdge = {
    WEST: 0,
    NORTH: 1,
    EAST: 2,
    SOUTH: 3,
    NORTHWEST: 4,
    NORTHEAST: 5,
    SOUTHWEST: 6,
    SOUTHEAST: 7,
  };

  /**
   * A tiling scheme for geometry or imagery on the surface of an ellipsoid.  At level-of-detail zero,
   * the coarsest, least-detailed level, the number of tiles is configurable.
   * At level of detail one, each of the level zero tiles has four children, two in each direction.
   * At level of detail two, each of the level one tiles has four children, two in each direction.
   * This continues for as many levels as are present in the geometry or imagery source.
   *
   * @alias TilingScheme
   * @constructor
   *
   * @see WebMercatorTilingScheme
   * @see GeographicTilingScheme
   */
  function TilingScheme(options) {
    //>>includeStart('debug', pragmas.debug);
    throw new DeveloperError(
      "This type should not be instantiated directly.  Instead, use WebMercatorTilingScheme or GeographicTilingScheme."
    );
    //>>includeEnd('debug');
  }

  Object.defineProperties(TilingScheme.prototype, {
    /**
     * Gets the ellipsoid that is tiled by the tiling scheme.
     * @memberof TilingScheme.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the rectangle, in radians, covered by this tiling scheme.
     * @memberof TilingScheme.prototype
     * @type {Rectangle}
     */
    rectangle: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the map projection used by the tiling scheme.
     * @memberof TilingScheme.prototype
     * @type {MapProjection}
     */
    projection: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Gets the total number of tiles in the X direction at a specified level-of-detail.
   * @function
   *
   * @param {Number} level The level-of-detail.
   * @returns {Number} The number of tiles in the X direction at the given level.
   */
  TilingScheme.prototype.getNumberOfXTilesAtLevel =
    DeveloperError.throwInstantiationError;

  /**
   * Gets the total number of tiles in the Y direction at a specified level-of-detail.
   * @function
   *
   * @param {Number} level The level-of-detail.
   * @returns {Number} The number of tiles in the Y direction at the given level.
   */
  TilingScheme.prototype.getNumberOfYTilesAtLevel =
    DeveloperError.throwInstantiationError;

  /**
   * Transforms a rectangle specified in geodetic radians to the native coordinate system
   * of this tiling scheme.
   * @function
   *
   * @param {Rectangle} rectangle The rectangle to transform.
   * @param {Rectangle} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the native rectangle if 'result'
   *          is undefined.
   */
  TilingScheme.prototype.rectangleToNativeRectangle =
    DeveloperError.throwInstantiationError;

  /**
   * Converts tile x, y coordinates and level to a rectangle expressed in the native coordinates
   * of the tiling scheme.
   * @function
   *
   * @param {Number} x The integer x coordinate of the tile.
   * @param {Number} y The integer y coordinate of the tile.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Object} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the rectangle
   *          if 'result' is undefined.
   */
  TilingScheme.prototype.tileXYToNativeRectangle =
    DeveloperError.throwInstantiationError;

  /**
   * Converts tile x, y coordinates and level to a cartographic rectangle in radians.
   * @function
   *
   * @param {Number} x The integer x coordinate of the tile.
   * @param {Number} y The integer y coordinate of the tile.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Object} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Rectangle} The specified 'result', or a new object containing the rectangle
   *          if 'result' is undefined.
   */
  TilingScheme.prototype.tileXYToRectangle =
    DeveloperError.throwInstantiationError;

  /**
   * Calculates the tile x, y coordinates of the tile containing
   * a given cartographic position.
   * @function
   *
   * @param {Cartographic} position The position.
   * @param {Number} level The tile level-of-detail.  Zero is the least detailed.
   * @param {Cartesian2} [result] The instance to which to copy the result, or undefined if a new instance
   *        should be created.
   * @returns {Cartesian2} The specified 'result', or a new object containing the tile x, y coordinates
   *          if 'result' is undefined.
   */
  TilingScheme.prototype.positionToTileXY =
    DeveloperError.throwInstantiationError;

  function compareIntervalStartTimes(left, right) {
    return JulianDate.compare(left.start, right.start);
  }

  /**
   * A non-overlapping collection of {@link TimeInterval} instances sorted by start time.
   * @alias TimeIntervalCollection
   * @constructor
   *
   * @param {TimeInterval[]} [intervals] An array of intervals to add to the collection.
   */
  function TimeIntervalCollection(intervals) {
    this._intervals = [];
    this._changedEvent = new Event();

    if (defined(intervals)) {
      var length = intervals.length;
      for (var i = 0; i < length; i++) {
        this.addInterval(intervals[i]);
      }
    }
  }

  Object.defineProperties(TimeIntervalCollection.prototype, {
    /**
     * Gets an event that is raised whenever the collection of intervals change.
     * @memberof TimeIntervalCollection.prototype
     * @type {Event}
     * @readonly
     */
    changedEvent: {
      get: function () {
        return this._changedEvent;
      },
    },

    /**
     * Gets the start time of the collection.
     * @memberof TimeIntervalCollection.prototype
     * @type {JulianDate}
     * @readonly
     */
    start: {
      get: function () {
        var intervals = this._intervals;
        return intervals.length === 0 ? undefined : intervals[0].start;
      },
    },

    /**
     * Gets whether or not the start time is included in the collection.
     * @memberof TimeIntervalCollection.prototype
     * @type {Boolean}
     * @readonly
     */
    isStartIncluded: {
      get: function () {
        var intervals = this._intervals;
        return intervals.length === 0 ? false : intervals[0].isStartIncluded;
      },
    },

    /**
     * Gets the stop time of the collection.
     * @memberof TimeIntervalCollection.prototype
     * @type {JulianDate}
     * @readonly
     */
    stop: {
      get: function () {
        var intervals = this._intervals;
        var length = intervals.length;
        return length === 0 ? undefined : intervals[length - 1].stop;
      },
    },

    /**
     * Gets whether or not the stop time is included in the collection.
     * @memberof TimeIntervalCollection.prototype
     * @type {Boolean}
     * @readonly
     */
    isStopIncluded: {
      get: function () {
        var intervals = this._intervals;
        var length = intervals.length;
        return length === 0 ? false : intervals[length - 1].isStopIncluded;
      },
    },

    /**
     * Gets the number of intervals in the collection.
     * @memberof TimeIntervalCollection.prototype
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._intervals.length;
      },
    },

    /**
     * Gets whether or not the collection is empty.
     * @memberof TimeIntervalCollection.prototype
     * @type {Boolean}
     * @readonly
     */
    isEmpty: {
      get: function () {
        return this._intervals.length === 0;
      },
    },
  });

  /**
   * Compares this instance against the provided instance componentwise and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {TimeIntervalCollection} [right] The right hand side collection.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  TimeIntervalCollection.prototype.equals = function (right, dataComparer) {
    if (this === right) {
      return true;
    }
    if (!(right instanceof TimeIntervalCollection)) {
      return false;
    }
    var intervals = this._intervals;
    var rightIntervals = right._intervals;
    var length = intervals.length;
    if (length !== rightIntervals.length) {
      return false;
    }
    for (var i = 0; i < length; i++) {
      if (!TimeInterval.equals(intervals[i], rightIntervals[i], dataComparer)) {
        return false;
      }
    }
    return true;
  };

  /**
   * Gets the interval at the specified index.
   *
   * @param {Number} index The index of the interval to retrieve.
   * @returns {TimeInterval|undefined} The interval at the specified index, or <code>undefined</code> if no interval exists as that index.
   */
  TimeIntervalCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    return this._intervals[index];
  };

  /**
   * Removes all intervals from the collection.
   */
  TimeIntervalCollection.prototype.removeAll = function () {
    if (this._intervals.length > 0) {
      this._intervals.length = 0;
      this._changedEvent.raiseEvent(this);
    }
  };

  /**
   * Finds and returns the interval that contains the specified date.
   *
   * @param {JulianDate} date The date to search for.
   * @returns {TimeInterval|undefined} The interval containing the specified date, <code>undefined</code> if no such interval exists.
   */
  TimeIntervalCollection.prototype.findIntervalContainingDate = function (date) {
    var index = this.indexOf(date);
    return index >= 0 ? this._intervals[index] : undefined;
  };

  /**
   * Finds and returns the data for the interval that contains the specified date.
   *
   * @param {JulianDate} date The date to search for.
   * @returns {Object} The data for the interval containing the specified date, or <code>undefined</code> if no such interval exists.
   */
  TimeIntervalCollection.prototype.findDataForIntervalContainingDate = function (
    date
  ) {
    var index = this.indexOf(date);
    return index >= 0 ? this._intervals[index].data : undefined;
  };

  /**
   * Checks if the specified date is inside this collection.
   *
   * @param {JulianDate} julianDate The date to check.
   * @returns {Boolean} <code>true</code> if the collection contains the specified date, <code>false</code> otherwise.
   */
  TimeIntervalCollection.prototype.contains = function (julianDate) {
    return this.indexOf(julianDate) >= 0;
  };

  var indexOfScratch = new TimeInterval();

  /**
   * Finds and returns the index of the interval in the collection that contains the specified date.
   *
   * @param {JulianDate} date The date to search for.
   * @returns {Number} The index of the interval that contains the specified date, if no such interval exists,
   * it returns a negative number which is the bitwise complement of the index of the next interval that
   * starts after the date, or if no interval starts after the specified date, the bitwise complement of
   * the length of the collection.
   */
  TimeIntervalCollection.prototype.indexOf = function (date) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(date)) {
      throw new DeveloperError("date is required");
    }
    //>>includeEnd('debug');

    var intervals = this._intervals;
    indexOfScratch.start = date;
    indexOfScratch.stop = date;
    var index = binarySearch(
      intervals,
      indexOfScratch,
      compareIntervalStartTimes
    );
    if (index >= 0) {
      if (intervals[index].isStartIncluded) {
        return index;
      }

      if (
        index > 0 &&
        intervals[index - 1].stop.equals(date) &&
        intervals[index - 1].isStopIncluded
      ) {
        return index - 1;
      }
      return ~index;
    }

    index = ~index;
    if (
      index > 0 &&
      index - 1 < intervals.length &&
      TimeInterval.contains(intervals[index - 1], date)
    ) {
      return index - 1;
    }
    return ~index;
  };

  /**
   * Returns the first interval in the collection that matches the specified parameters.
   * All parameters are optional and <code>undefined</code> parameters are treated as a don't care condition.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {JulianDate} [options.start] The start time of the interval.
   * @param {JulianDate} [options.stop] The stop time of the interval.
   * @param {Boolean} [options.isStartIncluded] <code>true</code> if <code>options.start</code> is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded] <code>true</code> if <code>options.stop</code> is included in the interval, <code>false</code> otherwise.
   * @returns {TimeInterval|undefined} The first interval in the collection that matches the specified parameters.
   */
  TimeIntervalCollection.prototype.findInterval = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var start = options.start;
    var stop = options.stop;
    var isStartIncluded = options.isStartIncluded;
    var isStopIncluded = options.isStopIncluded;

    var intervals = this._intervals;
    for (var i = 0, len = intervals.length; i < len; i++) {
      var interval = intervals[i];
      if (
        (!defined(start) || interval.start.equals(start)) &&
        (!defined(stop) || interval.stop.equals(stop)) &&
        (!defined(isStartIncluded) ||
          interval.isStartIncluded === isStartIncluded) &&
        (!defined(isStopIncluded) || interval.isStopIncluded === isStopIncluded)
      ) {
        return intervals[i];
      }
    }
    return undefined;
  };

  /**
   * Adds an interval to the collection, merging intervals that contain the same data and
   * splitting intervals of different data as needed in order to maintain a non-overlapping collection.
   * The data in the new interval takes precedence over any existing intervals in the collection.
   *
   * @param {TimeInterval} interval The interval to add.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   */
  TimeIntervalCollection.prototype.addInterval = function (
    interval,
    dataComparer
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(interval)) {
      throw new DeveloperError("interval is required");
    }
    //>>includeEnd('debug');

    if (interval.isEmpty) {
      return;
    }

    var intervals = this._intervals;

    // Handle the common case quickly: we're adding a new interval which is after all existing intervals.
    if (
      intervals.length === 0 ||
      JulianDate.greaterThan(interval.start, intervals[intervals.length - 1].stop)
    ) {
      intervals.push(interval);
      this._changedEvent.raiseEvent(this);
      return;
    }

    // Keep the list sorted by the start date
    var index = binarySearch(intervals, interval, compareIntervalStartTimes);
    if (index < 0) {
      index = ~index;
    } else {
      // interval's start date exactly equals the start date of at least one interval in the collection.
      // It could actually equal the start date of two intervals if one of them does not actually
      // include the date.  In that case, the binary search could have found either.  We need to
      // look at the surrounding intervals and their IsStartIncluded properties in order to make sure
      // we're working with the correct interval.

      // eslint-disable-next-line no-lonely-if
      if (
        index > 0 &&
        interval.isStartIncluded &&
        intervals[index - 1].isStartIncluded &&
        intervals[index - 1].start.equals(interval.start)
      ) {
        --index;
      } else if (
        index < intervals.length &&
        !interval.isStartIncluded &&
        intervals[index].isStartIncluded &&
        intervals[index].start.equals(interval.start)
      ) {
        ++index;
      }
    }

    var comparison;
    if (index > 0) {
      // Not the first thing in the list, so see if the interval before this one
      // overlaps this one.

      comparison = JulianDate.compare(intervals[index - 1].stop, interval.start);
      if (
        comparison > 0 ||
        (comparison === 0 &&
          (intervals[index - 1].isStopIncluded || interval.isStartIncluded))
      ) {
        // There is an overlap
        if (
          defined(dataComparer)
            ? dataComparer(intervals[index - 1].data, interval.data)
            : intervals[index - 1].data === interval.data
        ) {
          // Overlapping intervals have the same data, so combine them
          if (JulianDate.greaterThan(interval.stop, intervals[index - 1].stop)) {
            interval = new TimeInterval({
              start: intervals[index - 1].start,
              stop: interval.stop,
              isStartIncluded: intervals[index - 1].isStartIncluded,
              isStopIncluded: interval.isStopIncluded,
              data: interval.data,
            });
          } else {
            interval = new TimeInterval({
              start: intervals[index - 1].start,
              stop: intervals[index - 1].stop,
              isStartIncluded: intervals[index - 1].isStartIncluded,
              isStopIncluded:
                intervals[index - 1].isStopIncluded ||
                (interval.stop.equals(intervals[index - 1].stop) &&
                  interval.isStopIncluded),
              data: interval.data,
            });
          }
          intervals.splice(index - 1, 1);
          --index;
        } else {
          // Overlapping intervals have different data.  The new interval
          // being added 'wins' so truncate the previous interval.
          // If the existing interval extends past the end of the new one,
          // split the existing interval into two intervals.
          comparison = JulianDate.compare(
            intervals[index - 1].stop,
            interval.stop
          );
          if (
            comparison > 0 ||
            (comparison === 0 &&
              intervals[index - 1].isStopIncluded &&
              !interval.isStopIncluded)
          ) {
            intervals.splice(
              index,
              0,
              new TimeInterval({
                start: interval.stop,
                stop: intervals[index - 1].stop,
                isStartIncluded: !interval.isStopIncluded,
                isStopIncluded: intervals[index - 1].isStopIncluded,
                data: intervals[index - 1].data,
              })
            );
          }
          intervals[index - 1] = new TimeInterval({
            start: intervals[index - 1].start,
            stop: interval.start,
            isStartIncluded: intervals[index - 1].isStartIncluded,
            isStopIncluded: !interval.isStartIncluded,
            data: intervals[index - 1].data,
          });
        }
      }
    }

    while (index < intervals.length) {
      // Not the last thing in the list, so see if the intervals after this one overlap this one.
      comparison = JulianDate.compare(interval.stop, intervals[index].start);
      if (
        comparison > 0 ||
        (comparison === 0 &&
          (interval.isStopIncluded || intervals[index].isStartIncluded))
      ) {
        // There is an overlap
        if (
          defined(dataComparer)
            ? dataComparer(intervals[index].data, interval.data)
            : intervals[index].data === interval.data
        ) {
          // Overlapping intervals have the same data, so combine them
          interval = new TimeInterval({
            start: interval.start,
            stop: JulianDate.greaterThan(intervals[index].stop, interval.stop)
              ? intervals[index].stop
              : interval.stop,
            isStartIncluded: interval.isStartIncluded,
            isStopIncluded: JulianDate.greaterThan(
              intervals[index].stop,
              interval.stop
            )
              ? intervals[index].isStopIncluded
              : interval.isStopIncluded,
            data: interval.data,
          });
          intervals.splice(index, 1);
        } else {
          // Overlapping intervals have different data.  The new interval
          // being added 'wins' so truncate the next interval.
          intervals[index] = new TimeInterval({
            start: interval.stop,
            stop: intervals[index].stop,
            isStartIncluded: !interval.isStopIncluded,
            isStopIncluded: intervals[index].isStopIncluded,
            data: intervals[index].data,
          });

          if (intervals[index].isEmpty) {
            intervals.splice(index, 1);
          } else {
            // Found a partial span, so it is not possible for the next
            // interval to be spanned at all.  Stop looking.
            break;
          }
        }
      } else {
        // Found the last one we're spanning, so stop looking.
        break;
      }
    }

    // Add the new interval
    intervals.splice(index, 0, interval);
    this._changedEvent.raiseEvent(this);
  };

  /**
   * Removes the specified interval from this interval collection, creating a hole over the specified interval.
   * The data property of the input interval is ignored.
   *
   * @param {TimeInterval} interval The interval to remove.
   * @returns {Boolean} <code>true</code> if the interval was removed, <code>false</code> if no part of the interval was in the collection.
   */
  TimeIntervalCollection.prototype.removeInterval = function (interval) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(interval)) {
      throw new DeveloperError("interval is required");
    }
    //>>includeEnd('debug');

    if (interval.isEmpty) {
      return false;
    }

    var intervals = this._intervals;

    var index = binarySearch(intervals, interval, compareIntervalStartTimes);
    if (index < 0) {
      index = ~index;
    }

    var result = false;

    // Check for truncation of the end of the previous interval.
    if (
      index > 0 &&
      (JulianDate.greaterThan(intervals[index - 1].stop, interval.start) ||
        (intervals[index - 1].stop.equals(interval.start) &&
          intervals[index - 1].isStopIncluded &&
          interval.isStartIncluded))
    ) {
      result = true;

      if (
        JulianDate.greaterThan(intervals[index - 1].stop, interval.stop) ||
        (intervals[index - 1].isStopIncluded &&
          !interval.isStopIncluded &&
          intervals[index - 1].stop.equals(interval.stop))
      ) {
        // Break the existing interval into two pieces
        intervals.splice(
          index,
          0,
          new TimeInterval({
            start: interval.stop,
            stop: intervals[index - 1].stop,
            isStartIncluded: !interval.isStopIncluded,
            isStopIncluded: intervals[index - 1].isStopIncluded,
            data: intervals[index - 1].data,
          })
        );
      }
      intervals[index - 1] = new TimeInterval({
        start: intervals[index - 1].start,
        stop: interval.start,
        isStartIncluded: intervals[index - 1].isStartIncluded,
        isStopIncluded: !interval.isStartIncluded,
        data: intervals[index - 1].data,
      });
    }

    // Check if the Start of the current interval should remain because interval.start is the same but
    // it is not included.
    if (
      index < intervals.length &&
      !interval.isStartIncluded &&
      intervals[index].isStartIncluded &&
      interval.start.equals(intervals[index].start)
    ) {
      result = true;

      intervals.splice(
        index,
        0,
        new TimeInterval({
          start: intervals[index].start,
          stop: intervals[index].start,
          isStartIncluded: true,
          isStopIncluded: true,
          data: intervals[index].data,
        })
      );
      ++index;
    }

    // Remove any intervals that are completely overlapped by the input interval.
    while (
      index < intervals.length &&
      JulianDate.greaterThan(interval.stop, intervals[index].stop)
    ) {
      result = true;
      intervals.splice(index, 1);
    }

    // Check for the case where the input interval ends on the same date
    // as an existing interval.
    if (index < intervals.length && interval.stop.equals(intervals[index].stop)) {
      result = true;

      if (!interval.isStopIncluded && intervals[index].isStopIncluded) {
        // Last point of interval should remain because the stop date is included in
        // the existing interval but is not included in the input interval.
        if (
          index + 1 < intervals.length &&
          intervals[index + 1].start.equals(interval.stop) &&
          intervals[index].data === intervals[index + 1].data
        ) {
          // Combine single point with the next interval
          intervals.splice(index, 1);
          intervals[index] = new TimeInterval({
            start: intervals[index].start,
            stop: intervals[index].stop,
            isStartIncluded: true,
            isStopIncluded: intervals[index].isStopIncluded,
            data: intervals[index].data,
          });
        } else {
          intervals[index] = new TimeInterval({
            start: interval.stop,
            stop: interval.stop,
            isStartIncluded: true,
            isStopIncluded: true,
            data: intervals[index].data,
          });
        }
      } else {
        // Interval is completely overlapped
        intervals.splice(index, 1);
      }
    }

    // Truncate any partially-overlapped intervals.
    if (
      index < intervals.length &&
      (JulianDate.greaterThan(interval.stop, intervals[index].start) ||
        (interval.stop.equals(intervals[index].start) &&
          interval.isStopIncluded &&
          intervals[index].isStartIncluded))
    ) {
      result = true;
      intervals[index] = new TimeInterval({
        start: interval.stop,
        stop: intervals[index].stop,
        isStartIncluded: !interval.isStopIncluded,
        isStopIncluded: intervals[index].isStopIncluded,
        data: intervals[index].data,
      });
    }

    if (result) {
      this._changedEvent.raiseEvent(this);
    }

    return result;
  };

  /**
   * Creates a new instance that is the intersection of this collection and the provided collection.
   *
   * @param {TimeIntervalCollection} other The collection to intersect with.
   * @param {TimeInterval.DataComparer} [dataComparer] A function which compares the data of the two intervals.  If omitted, reference equality is used.
   * @param {TimeInterval.MergeCallback} [mergeCallback] A function which merges the data of the two intervals. If omitted, the data from the left interval will be used.
   * @returns {TimeIntervalCollection} A new TimeIntervalCollection which is the intersection of this collection and the provided collection.
   */
  TimeIntervalCollection.prototype.intersect = function (
    other,
    dataComparer,
    mergeCallback
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(other)) {
      throw new DeveloperError("other is required.");
    }
    //>>includeEnd('debug');

    var result = new TimeIntervalCollection();
    var left = 0;
    var right = 0;
    var intervals = this._intervals;
    var otherIntervals = other._intervals;

    while (left < intervals.length && right < otherIntervals.length) {
      var leftInterval = intervals[left];
      var rightInterval = otherIntervals[right];
      if (JulianDate.lessThan(leftInterval.stop, rightInterval.start)) {
        ++left;
      } else if (JulianDate.lessThan(rightInterval.stop, leftInterval.start)) {
        ++right;
      } else {
        // The following will return an intersection whose data is 'merged' if the callback is defined
        if (
          defined(mergeCallback) ||
          (defined(dataComparer) &&
            dataComparer(leftInterval.data, rightInterval.data)) ||
          (!defined(dataComparer) && rightInterval.data === leftInterval.data)
        ) {
          var intersection = TimeInterval.intersect(
            leftInterval,
            rightInterval,
            new TimeInterval(),
            mergeCallback
          );
          if (!intersection.isEmpty) {
            // Since we start with an empty collection for 'result', and there are no overlapping intervals in 'this' (as a rule),
            // the 'intersection' will never overlap with a previous interval in 'result'.  So, no need to do any additional 'merging'.
            result.addInterval(intersection, dataComparer);
          }
        }

        if (
          JulianDate.lessThan(leftInterval.stop, rightInterval.stop) ||
          (leftInterval.stop.equals(rightInterval.stop) &&
            !leftInterval.isStopIncluded &&
            rightInterval.isStopIncluded)
        ) {
          ++left;
        } else {
          ++right;
        }
      }
    }
    return result;
  };

  /**
   * Creates a new instance from a JulianDate array.
   *
   * @param {Object} options Object with the following properties:
   * @param {JulianDate[]} options.julianDates An array of ISO 8601 dates.
   * @param {Boolean} [options.isStartIncluded=true] <code>true</code> if start time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded=true] <code>true</code> if stop time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.leadingInterval=false] <code>true</code> if you want to add a interval from Iso8601.MINIMUM_VALUE to start time,  <code>false</code> otherwise.
   * @param {Boolean} [options.trailingInterval=false] <code>true</code> if you want to add a interval from stop time to Iso8601.MAXIMUM_VALUE,  <code>false</code> otherwise.
   * @param {Function} [options.dataCallback] A function that will be return the data that is called with each interval before it is added to the collection. If unspecified, the data will be the index in the collection.
   * @param {TimeIntervalCollection} [result] An existing instance to use for the result.
   * @returns {TimeIntervalCollection} The modified result parameter or a new instance if none was provided.
   */
  TimeIntervalCollection.fromJulianDateArray = function (options, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!defined(options.julianDates)) {
      throw new DeveloperError("options.iso8601Array is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new TimeIntervalCollection();
    }

    var julianDates = options.julianDates;
    var length = julianDates.length;
    var dataCallback = options.dataCallback;

    var isStartIncluded = defaultValue(options.isStartIncluded, true);
    var isStopIncluded = defaultValue(options.isStopIncluded, true);
    var leadingInterval = defaultValue(options.leadingInterval, false);
    var trailingInterval = defaultValue(options.trailingInterval, false);
    var interval;

    // Add a default interval, which will only end up being used up to first interval
    var startIndex = 0;
    if (leadingInterval) {
      ++startIndex;
      interval = new TimeInterval({
        start: Iso8601.MINIMUM_VALUE,
        stop: julianDates[0],
        isStartIncluded: true,
        isStopIncluded: !isStartIncluded,
      });
      interval.data = defined(dataCallback)
        ? dataCallback(interval, result.length)
        : result.length;
      result.addInterval(interval);
    }

    for (var i = 0; i < length - 1; ++i) {
      var startDate = julianDates[i];
      var endDate = julianDates[i + 1];

      interval = new TimeInterval({
        start: startDate,
        stop: endDate,
        isStartIncluded: result.length === startIndex ? isStartIncluded : true,
        isStopIncluded: i === length - 2 ? isStopIncluded : false,
      });
      interval.data = defined(dataCallback)
        ? dataCallback(interval, result.length)
        : result.length;
      result.addInterval(interval);

      startDate = endDate;
    }

    if (trailingInterval) {
      interval = new TimeInterval({
        start: julianDates[length - 1],
        stop: Iso8601.MAXIMUM_VALUE,
        isStartIncluded: !isStopIncluded,
        isStopIncluded: true,
      });
      interval.data = defined(dataCallback)
        ? dataCallback(interval, result.length)
        : result.length;
      result.addInterval(interval);
    }

    return result;
  };

  var scratchGregorianDate = new GregorianDate();
  var monthLengths = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];

  /**
   * Adds duration represented as a GregorianDate to a JulianDate
   *
   * @param {JulianDate} julianDate The date.
   * @param {GregorianDate} duration An duration represented as a GregorianDate.
   * @param {JulianDate} result An existing instance to use for the result.
   * @returns {JulianDate} The modified result parameter.
   *
   * @private
   */
  function addToDate(julianDate, duration, result) {
    if (!defined(result)) {
      result = new JulianDate();
    }
    JulianDate.toGregorianDate(julianDate, scratchGregorianDate);

    var millisecond = scratchGregorianDate.millisecond + duration.millisecond;
    var second = scratchGregorianDate.second + duration.second;
    var minute = scratchGregorianDate.minute + duration.minute;
    var hour = scratchGregorianDate.hour + duration.hour;
    var day = scratchGregorianDate.day + duration.day;
    var month = scratchGregorianDate.month + duration.month;
    var year = scratchGregorianDate.year + duration.year;

    if (millisecond >= 1000) {
      second += Math.floor(millisecond / 1000);
      millisecond = millisecond % 1000;
    }

    if (second >= 60) {
      minute += Math.floor(second / 60);
      second = second % 60;
    }

    if (minute >= 60) {
      hour += Math.floor(minute / 60);
      minute = minute % 60;
    }

    if (hour >= 24) {
      day += Math.floor(hour / 24);
      hour = hour % 24;
    }

    // If days is greater than the month's length we need to remove those number of days,
    //  readjust month and year and repeat until days is less than the month's length.
    monthLengths[2] = isLeapYear(year) ? 29 : 28;
    while (day > monthLengths[month] || month >= 13) {
      if (day > monthLengths[month]) {
        day -= monthLengths[month];
        ++month;
      }

      if (month >= 13) {
        --month;
        year += Math.floor(month / 12);
        month = month % 12;
        ++month;
      }

      monthLengths[2] = isLeapYear(year) ? 29 : 28;
    }

    scratchGregorianDate.millisecond = millisecond;
    scratchGregorianDate.second = second;
    scratchGregorianDate.minute = minute;
    scratchGregorianDate.hour = hour;
    scratchGregorianDate.day = day;
    scratchGregorianDate.month = month;
    scratchGregorianDate.year = year;

    return JulianDate.fromGregorianDate(scratchGregorianDate, result);
  }

  var scratchJulianDate = new JulianDate();
  var durationRegex = /P(?:([\d.,]+)Y)?(?:([\d.,]+)M)?(?:([\d.,]+)W)?(?:([\d.,]+)D)?(?:T(?:([\d.,]+)H)?(?:([\d.,]+)M)?(?:([\d.,]+)S)?)?/;

  /**
   * Parses ISO8601 duration string
   *
   * @param {String} iso8601 An ISO 8601 duration.
   * @param {GregorianDate} result An existing instance to use for the result.
   * @returns {Boolean} True is parsing succeeded, false otherwise
   *
   * @private
   */
  function parseDuration(iso8601, result) {
    if (!defined(iso8601) || iso8601.length === 0) {
      return false;
    }

    // Reset object
    result.year = 0;
    result.month = 0;
    result.day = 0;
    result.hour = 0;
    result.minute = 0;
    result.second = 0;
    result.millisecond = 0;

    if (iso8601[0] === "P") {
      var matches = iso8601.match(durationRegex);
      if (!defined(matches)) {
        return false;
      }
      if (defined(matches[1])) {
        // Years
        result.year = Number(matches[1].replace(",", "."));
      }
      if (defined(matches[2])) {
        // Months
        result.month = Number(matches[2].replace(",", "."));
      }
      if (defined(matches[3])) {
        // Weeks
        result.day = Number(matches[3].replace(",", ".")) * 7;
      }
      if (defined(matches[4])) {
        // Days
        result.day += Number(matches[4].replace(",", "."));
      }
      if (defined(matches[5])) {
        // Hours
        result.hour = Number(matches[5].replace(",", "."));
      }
      if (defined(matches[6])) {
        // Weeks
        result.minute = Number(matches[6].replace(",", "."));
      }
      if (defined(matches[7])) {
        // Seconds
        var seconds = Number(matches[7].replace(",", "."));
        result.second = Math.floor(seconds);
        result.millisecond = (seconds % 1) * 1000;
      }
    } else {
      // They can technically specify the duration as a normal date with some caveats. Try our best to load it.
      if (iso8601[iso8601.length - 1] !== "Z") {
        // It's not a date, its a duration, so it always has to be UTC
        iso8601 += "Z";
      }
      JulianDate.toGregorianDate(
        JulianDate.fromIso8601(iso8601, scratchJulianDate),
        result
      );
    }

    // A duration of 0 will cause an infinite loop, so just make sure something is non-zero
    return (
      result.year ||
      result.month ||
      result.day ||
      result.hour ||
      result.minute ||
      result.second ||
      result.millisecond
    );
  }

  var scratchDuration = new GregorianDate();
  /**
   * Creates a new instance from an {@link http://en.wikipedia.org/wiki/ISO_8601|ISO 8601} time interval (start/end/duration).
   *
   * @param {Object} options Object with the following properties:
   * @param {String} options.iso8601 An ISO 8601 interval.
   * @param {Boolean} [options.isStartIncluded=true] <code>true</code> if start time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded=true] <code>true</code> if stop time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.leadingInterval=false] <code>true</code> if you want to add a interval from Iso8601.MINIMUM_VALUE to start time,  <code>false</code> otherwise.
   * @param {Boolean} [options.trailingInterval=false] <code>true</code> if you want to add a interval from stop time to Iso8601.MAXIMUM_VALUE,  <code>false</code> otherwise.
   * @param {Function} [options.dataCallback] A function that will be return the data that is called with each interval before it is added to the collection. If unspecified, the data will be the index in the collection.
   * @param {TimeIntervalCollection} [result] An existing instance to use for the result.
   * @returns {TimeIntervalCollection} The modified result parameter or a new instance if none was provided.
   */
  TimeIntervalCollection.fromIso8601 = function (options, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!defined(options.iso8601)) {
      throw new DeveloperError("options.iso8601 is required.");
    }
    //>>includeEnd('debug');

    var dates = options.iso8601.split("/");
    var start = JulianDate.fromIso8601(dates[0]);
    var stop = JulianDate.fromIso8601(dates[1]);
    var julianDates = [];

    if (!parseDuration(dates[2], scratchDuration)) {
      julianDates.push(start, stop);
    } else {
      var date = JulianDate.clone(start);
      julianDates.push(date);
      while (JulianDate.compare(date, stop) < 0) {
        date = addToDate(date, scratchDuration);
        var afterStop = JulianDate.compare(stop, date) <= 0;
        if (afterStop) {
          JulianDate.clone(stop, date);
        }

        julianDates.push(date);
      }
    }

    return TimeIntervalCollection.fromJulianDateArray(
      {
        julianDates: julianDates,
        isStartIncluded: options.isStartIncluded,
        isStopIncluded: options.isStopIncluded,
        leadingInterval: options.leadingInterval,
        trailingInterval: options.trailingInterval,
        dataCallback: options.dataCallback,
      },
      result
    );
  };

  /**
   * Creates a new instance from a {@link http://en.wikipedia.org/wiki/ISO_8601|ISO 8601} date array.
   *
   * @param {Object} options Object with the following properties:
   * @param {String[]} options.iso8601Dates An array of ISO 8601 dates.
   * @param {Boolean} [options.isStartIncluded=true] <code>true</code> if start time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded=true] <code>true</code> if stop time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.leadingInterval=false] <code>true</code> if you want to add a interval from Iso8601.MINIMUM_VALUE to start time,  <code>false</code> otherwise.
   * @param {Boolean} [options.trailingInterval=false] <code>true</code> if you want to add a interval from stop time to Iso8601.MAXIMUM_VALUE,  <code>false</code> otherwise.
   * @param {Function} [options.dataCallback] A function that will be return the data that is called with each interval before it is added to the collection. If unspecified, the data will be the index in the collection.
   * @param {TimeIntervalCollection} [result] An existing instance to use for the result.
   * @returns {TimeIntervalCollection} The modified result parameter or a new instance if none was provided.
   */
  TimeIntervalCollection.fromIso8601DateArray = function (options, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!defined(options.iso8601Dates)) {
      throw new DeveloperError("options.iso8601Dates is required.");
    }
    //>>includeEnd('debug');

    return TimeIntervalCollection.fromJulianDateArray(
      {
        julianDates: options.iso8601Dates.map(function (date) {
          return JulianDate.fromIso8601(date);
        }),
        isStartIncluded: options.isStartIncluded,
        isStopIncluded: options.isStopIncluded,
        leadingInterval: options.leadingInterval,
        trailingInterval: options.trailingInterval,
        dataCallback: options.dataCallback,
      },
      result
    );
  };

  /**
   * Creates a new instance from a {@link http://en.wikipedia.org/wiki/ISO_8601|ISO 8601} duration array.
   *
   * @param {Object} options Object with the following properties:
   * @param {JulianDate} options.epoch An date that the durations are relative to.
   * @param {String} options.iso8601Durations An array of ISO 8601 durations.
   * @param {Boolean} [options.relativeToPrevious=false] <code>true</code> if durations are relative to previous date, <code>false</code> if always relative to the epoch.
   * @param {Boolean} [options.isStartIncluded=true] <code>true</code> if start time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.isStopIncluded=true] <code>true</code> if stop time is included in the interval, <code>false</code> otherwise.
   * @param {Boolean} [options.leadingInterval=false] <code>true</code> if you want to add a interval from Iso8601.MINIMUM_VALUE to start time,  <code>false</code> otherwise.
   * @param {Boolean} [options.trailingInterval=false] <code>true</code> if you want to add a interval from stop time to Iso8601.MAXIMUM_VALUE,  <code>false</code> otherwise.
   * @param {Function} [options.dataCallback] A function that will be return the data that is called with each interval before it is added to the collection. If unspecified, the data will be the index in the collection.
   * @param {TimeIntervalCollection} [result] An existing instance to use for the result.
   * @returns {TimeIntervalCollection} The modified result parameter or a new instance if none was provided.
   */
  TimeIntervalCollection.fromIso8601DurationArray = function (options, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!defined(options.epoch)) {
      throw new DeveloperError("options.epoch is required.");
    }
    if (!defined(options.iso8601Durations)) {
      throw new DeveloperError("options.iso8601Durations is required.");
    }
    //>>includeEnd('debug');

    var epoch = options.epoch;
    var iso8601Durations = options.iso8601Durations;
    var relativeToPrevious = defaultValue(options.relativeToPrevious, false);
    var julianDates = [];
    var date, previousDate;

    var length = iso8601Durations.length;
    for (var i = 0; i < length; ++i) {
      // Allow a duration of 0 on the first iteration, because then it is just the epoch
      if (parseDuration(iso8601Durations[i], scratchDuration) || i === 0) {
        if (relativeToPrevious && defined(previousDate)) {
          date = addToDate(previousDate, scratchDuration);
        } else {
          date = addToDate(epoch, scratchDuration);
        }
        julianDates.push(date);
        previousDate = date;
      }
    }

    return TimeIntervalCollection.fromJulianDateArray(
      {
        julianDates: julianDates,
        isStartIncluded: options.isStartIncluded,
        isStopIncluded: options.isStopIncluded,
        leadingInterval: options.leadingInterval,
        trailingInterval: options.trailingInterval,
        dataCallback: options.dataCallback,
      },
      result
    );
  };

  var defaultScale = new Cartesian3(1.0, 1.0, 1.0);
  var defaultTranslation = Cartesian3.ZERO;
  var defaultRotation = Quaternion.IDENTITY;

  /**
   * An affine transformation defined by a translation, rotation, and scale.
   * @alias TranslationRotationScale
   * @constructor
   *
   * @param {Cartesian3} [translation=Cartesian3.ZERO] A {@link Cartesian3} specifying the (x, y, z) translation to apply to the node.
   * @param {Quaternion} [rotation=Quaternion.IDENTITY] A {@link Quaternion} specifying the (x, y, z, w) rotation to apply to the node.
   * @param {Cartesian3} [scale=new Cartesian3(1.0, 1.0, 1.0)] A {@link Cartesian3} specifying the (x, y, z) scaling to apply to the node.
   */
  function TranslationRotationScale(translation, rotation, scale) {
    /**
     * Gets or sets the (x, y, z) translation to apply to the node.
     * @type {Cartesian3}
     * @default Cartesian3.ZERO
     */
    this.translation = Cartesian3.clone(
      defaultValue(translation, defaultTranslation)
    );

    /**
     * Gets or sets the (x, y, z, w) rotation to apply to the node.
     * @type {Quaternion}
     * @default Quaternion.IDENTITY
     */
    this.rotation = Quaternion.clone(defaultValue(rotation, defaultRotation));

    /**
     * Gets or sets the (x, y, z) scaling to apply to the node.
     * @type {Cartesian3}
     * @default new Cartesian3(1.0, 1.0, 1.0)
     */
    this.scale = Cartesian3.clone(defaultValue(scale, defaultScale));
  }

  /**
   * Compares this instance against the provided instance and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {TranslationRotationScale} [right] The right hand side TranslationRotationScale.
   * @returns {Boolean} <code>true</code> if they are equal, <code>false</code> otherwise.
   */
  TranslationRotationScale.prototype.equals = function (right) {
    return (
      this === right ||
      (defined(right) &&
        Cartesian3.equals(this.translation, right.translation) &&
        Quaternion.equals(this.rotation, right.rotation) &&
        Cartesian3.equals(this.scale, right.scale))
    );
  };

  var context2DsByWidthAndHeight = {};

  /**
   * Extract a pixel array from a loaded image.  Draws the image
   * into a canvas so it can read the pixels back.
   *
   * @function getImagePixels
   *
   * @param {HTMLImageElement} image The image to extract pixels from.
   * @param {Number} width The width of the image. If not defined, then image.width is assigned.
   * @param {Number} height The height of the image. If not defined, then image.height is assigned.
   * @returns {ImageData} The pixels of the image.
   */
  function getImagePixels(image, width, height) {
    if (!defined(width)) {
      width = image.width;
    }
    if (!defined(height)) {
      height = image.height;
    }

    var context2DsByHeight = context2DsByWidthAndHeight[width];
    if (!defined(context2DsByHeight)) {
      context2DsByHeight = {};
      context2DsByWidthAndHeight[width] = context2DsByHeight;
    }

    var context2d = context2DsByHeight[height];
    if (!defined(context2d)) {
      var canvas = document.createElement("canvas");
      canvas.width = width;
      canvas.height = height;
      context2d = canvas.getContext("2d");
      context2d.globalCompositeOperation = "copy";
      context2DsByHeight[height] = context2d;
    }

    context2d.drawImage(image, 0, 0, width, height);
    return context2d.getImageData(0, 0, width, height).data;
  }

  function DataRectangle(rectangle, maxLevel) {
    this.rectangle = rectangle;
    this.maxLevel = maxLevel;
  }

  /**
   * A {@link TerrainProvider} that produces terrain geometry by tessellating height maps
   * retrieved from a {@link http://vr-theworld.com/|VT MÄK VR-TheWorld server}.
   *
   * @alias VRTheWorldTerrainProvider
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String} options.url The URL of the VR-TheWorld TileMap.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid.  If this parameter is not
   *                    specified, the WGS84 ellipsoid is used.
   * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
   *
   *
   * @example
   * var terrainProvider = new Cesium.VRTheWorldTerrainProvider({
   *   url : 'https://www.vr-theworld.com/vr-theworld/tiles1.0.0/73/'
   * });
   * viewer.terrainProvider = terrainProvider;
   *
   * @see TerrainProvider
   */
  function VRTheWorldTerrainProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    //>>includeEnd('debug');

    var resource = Resource.createIfNeeded(options.url);

    this._resource = resource;

    this._errorEvent = new Event();
    this._ready = false;
    this._readyPromise = when.defer();

    this._terrainDataStructure = {
      heightScale: 1.0 / 1000.0,
      heightOffset: -1000.0,
      elementsPerHeight: 3,
      stride: 4,
      elementMultiplier: 256.0,
      isBigEndian: true,
      lowestEncodedHeight: 0,
      highestEncodedHeight: 256 * 256 * 256 - 1,
    };

    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    this._tilingScheme = undefined;
    this._rectangles = [];

    var that = this;
    var metadataError;
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    function metadataSuccess(xml) {
      var srs = xml.getElementsByTagName("SRS")[0].textContent;
      if (srs === "EPSG:4326") {
        that._tilingScheme = new GeographicTilingScheme({ ellipsoid: ellipsoid });
      } else {
        metadataFailure("SRS " + srs + " is not supported.");
        return;
      }

      var tileFormat = xml.getElementsByTagName("TileFormat")[0];
      that._heightmapWidth = parseInt(tileFormat.getAttribute("width"), 10);
      that._heightmapHeight = parseInt(tileFormat.getAttribute("height"), 10);
      that._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
        ellipsoid,
        Math.min(that._heightmapWidth, that._heightmapHeight),
        that._tilingScheme.getNumberOfXTilesAtLevel(0)
      );

      var dataRectangles = xml.getElementsByTagName("DataExtent");

      for (var i = 0; i < dataRectangles.length; ++i) {
        var dataRectangle = dataRectangles[i];

        var west = CesiumMath.toRadians(
          parseFloat(dataRectangle.getAttribute("minx"))
        );
        var south = CesiumMath.toRadians(
          parseFloat(dataRectangle.getAttribute("miny"))
        );
        var east = CesiumMath.toRadians(
          parseFloat(dataRectangle.getAttribute("maxx"))
        );
        var north = CesiumMath.toRadians(
          parseFloat(dataRectangle.getAttribute("maxy"))
        );
        var maxLevel = parseInt(dataRectangle.getAttribute("maxlevel"), 10);

        that._rectangles.push(
          new DataRectangle(new Rectangle(west, south, east, north), maxLevel)
        );
      }

      that._ready = true;
      that._readyPromise.resolve(true);
    }

    function metadataFailure(e) {
      var message = defaultValue(
        e,
        "An error occurred while accessing " + that._resource.url + "."
      );
      metadataError = TileProviderError.handleError(
        metadataError,
        that,
        that._errorEvent,
        message,
        undefined,
        undefined,
        undefined,
        requestMetadata
      );
    }

    function requestMetadata() {
      when(that._resource.fetchXML(), metadataSuccess, metadataFailure);
    }

    requestMetadata();
  }

  Object.defineProperties(VRTheWorldTerrainProvider.prototype, {
    /**
     * Gets an event that is raised when the terrain provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets the credit to display when this terrain provider is active.  Typically this is used to credit
     * the source of the terrain.  This function should not be called before {@link VRTheWorldTerrainProvider#ready} returns true.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link VRTheWorldTerrainProvider#ready} returns true.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {GeographicTilingScheme}
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "requestTileGeometry must not be called before ready returns true."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Gets a value indicating whether or not the provider includes a water mask.  The water mask
     * indicates which areas of the globe are water rather than land, so they can be rendered
     * as a reflective surface with animated waves.  This function should not be
     * called before {@link VRTheWorldTerrainProvider#ready} returns true.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {Boolean}
     */
    hasWaterMask: {
      get: function () {
        return false;
      },
    },

    /**
     * Gets a value indicating whether or not the requested tiles include vertex normals.
     * This function should not be called before {@link VRTheWorldTerrainProvider#ready} returns true.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {Boolean}
     */
    hasVertexNormals: {
      get: function () {
        return false;
      },
    },
    /**
     * Gets an object that can be used to determine availability of terrain from this provider, such as
     * at points and in rectangles.  This function should not be called before
     * {@link TerrainProvider#ready} returns true.  This property may be undefined if availability
     * information is not available.
     * @memberof VRTheWorldTerrainProvider.prototype
     * @type {TileAvailability}
     */
    availability: {
      get: function () {
        return undefined;
      },
    },
  });

  /**
   * Requests the geometry for a given tile.  This function should not be called before
   * {@link VRTheWorldTerrainProvider#ready} returns true.  The result includes terrain
   * data and indicates that all child tiles are available.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry.  If this method
   *          returns undefined instead of a promise, it is an indication that too many requests are already
   *          pending and the request will be retried later.
   */
  VRTheWorldTerrainProvider.prototype.requestTileGeometry = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this.ready) {
      throw new DeveloperError(
        "requestTileGeometry must not be called before ready returns true."
      );
    }
    //>>includeEnd('debug');

    var yTiles = this._tilingScheme.getNumberOfYTilesAtLevel(level);
    var resource = this._resource.getDerivedResource({
      url: level + "/" + x + "/" + (yTiles - y - 1) + ".tif",
      queryParameters: {
        cesium: true,
      },
      request: request,
    });
    var promise = resource.fetchImage({
      preferImageBitmap: true,
    });
    if (!defined(promise)) {
      return undefined;
    }

    var that = this;
    return when(promise).then(function (image) {
      return new HeightmapTerrainData({
        buffer: getImagePixels(image),
        width: that._heightmapWidth,
        height: that._heightmapHeight,
        childTileMask: getChildMask(that, x, y, level),
        structure: that._terrainDataStructure,
      });
    });
  };

  /**
   * Gets the maximum geometric error allowed in a tile at a given level.
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error.
   */
  VRTheWorldTerrainProvider.prototype.getLevelMaximumGeometricError = function (
    level
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this.ready) {
      throw new DeveloperError(
        "requestTileGeometry must not be called before ready returns true."
      );
    }
    //>>includeEnd('debug');
    return this._levelZeroMaximumGeometricError / (1 << level);
  };

  var rectangleScratch$4 = new Rectangle();

  function getChildMask(provider, x, y, level) {
    var tilingScheme = provider._tilingScheme;
    var rectangles = provider._rectangles;
    var parentRectangle = tilingScheme.tileXYToRectangle(x, y, level);

    var childMask = 0;

    for (var i = 0; i < rectangles.length && childMask !== 15; ++i) {
      var rectangle = rectangles[i];
      if (rectangle.maxLevel <= level) {
        continue;
      }

      var testRectangle = rectangle.rectangle;

      var intersection = Rectangle.intersection(
        testRectangle,
        parentRectangle,
        rectangleScratch$4
      );
      if (defined(intersection)) {
        // Parent tile is inside this rectangle, so at least one child is, too.
        if (
          isTileInRectangle(tilingScheme, testRectangle, x * 2, y * 2, level + 1)
        ) {
          childMask |= 4; // northwest
        }
        if (
          isTileInRectangle(
            tilingScheme,
            testRectangle,
            x * 2 + 1,
            y * 2,
            level + 1
          )
        ) {
          childMask |= 8; // northeast
        }
        if (
          isTileInRectangle(
            tilingScheme,
            testRectangle,
            x * 2,
            y * 2 + 1,
            level + 1
          )
        ) {
          childMask |= 1; // southwest
        }
        if (
          isTileInRectangle(
            tilingScheme,
            testRectangle,
            x * 2 + 1,
            y * 2 + 1,
            level + 1
          )
        ) {
          childMask |= 2; // southeast
        }
      }
    }

    return childMask;
  }

  function isTileInRectangle(tilingScheme, rectangle, x, y, level) {
    var tileRectangle = tilingScheme.tileXYToRectangle(x, y, level);
    return defined(
      Rectangle.intersection(tileRectangle, rectangle, rectangleScratch$4)
    );
  }

  /**
   * Determines whether data for a tile is available to be loaded.
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {Boolean} Undefined if not supported, otherwise true or false.
   */
  VRTheWorldTerrainProvider.prototype.getTileDataAvailable = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Makes sure we load availability data for a tile
   *
   * @param {Number} x The X coordinate of the tile for which to request geometry.
   * @param {Number} y The Y coordinate of the tile for which to request geometry.
   * @param {Number} level The level of the tile for which to request geometry.
   * @returns {undefined|Promise<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
   */
  VRTheWorldTerrainProvider.prototype.loadTileDataAvailability = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Synchronizes a video element with a simulation clock.
   *
   * @alias VideoSynchronizer
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Clock} [options.clock] The clock instance used to drive the video.
   * @param {HTMLVideoElement} [options.element] The video element to be synchronized.
   * @param {JulianDate} [options.epoch=Iso8601.MINIMUM_VALUE] The simulation time that marks the start of the video.
   * @param {Number} [options.tolerance=1.0] The maximum amount of time, in seconds, that the clock and video can diverge.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Video.html|Video Material Demo}
   */
  function VideoSynchronizer(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._clock = undefined;
    this._element = undefined;
    this._clockSubscription = undefined;
    this._seekFunction = undefined;
    this._lastPlaybackRate = undefined;

    this.clock = options.clock;
    this.element = options.element;

    /**
     * Gets or sets the simulation time that marks the start of the video.
     * @type {JulianDate}
     * @default Iso8601.MINIMUM_VALUE
     */
    this.epoch = defaultValue(options.epoch, Iso8601.MINIMUM_VALUE);

    /**
     * Gets or sets the amount of time in seconds the video's currentTime
     * and the clock's currentTime can diverge before a video seek is performed.
     * Lower values make the synchronization more accurate but video
     * performance might suffer.  Higher values provide better performance
     * but at the cost of accuracy.
     * @type {Number}
     * @default 1.0
     */
    this.tolerance = defaultValue(options.tolerance, 1.0);

    this._seeking = false;
    this._seekFunction = undefined;
    this._firstTickAfterSeek = false;
  }

  Object.defineProperties(VideoSynchronizer.prototype, {
    /**
     * Gets or sets the clock used to drive the video element.
     *
     * @memberof VideoSynchronizer.prototype
     * @type {Clock}
     */
    clock: {
      get: function () {
        return this._clock;
      },
      set: function (value) {
        var oldValue = this._clock;

        if (oldValue === value) {
          return;
        }

        if (defined(oldValue)) {
          this._clockSubscription();
          this._clockSubscription = undefined;
        }

        if (defined(value)) {
          this._clockSubscription = value.onTick.addEventListener(
            VideoSynchronizer.prototype._onTick,
            this
          );
        }

        this._clock = value;
      },
    },
    /**
     * Gets or sets the video element to synchronize.
     *
     * @memberof VideoSynchronizer.prototype
     * @type {HTMLVideoElement}
     */
    element: {
      get: function () {
        return this._element;
      },
      set: function (value) {
        var oldValue = this._element;

        if (oldValue === value) {
          return;
        }

        if (defined(oldValue)) {
          oldValue.removeEventListener("seeked", this._seekFunction, false);
        }

        if (defined(value)) {
          this._seeking = false;
          this._seekFunction = createSeekFunction(this);
          value.addEventListener("seeked", this._seekFunction, false);
        }

        this._element = value;
        this._seeking = false;
        this._firstTickAfterSeek = false;
      },
    },
  });

  /**
   * Destroys and resources used by the object.  Once an object is destroyed, it should not be used.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  VideoSynchronizer.prototype.destroy = function () {
    this.element = undefined;
    this.clock = undefined;
    return destroyObject(this);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  VideoSynchronizer.prototype.isDestroyed = function () {
    return false;
  };

  VideoSynchronizer.prototype._trySetPlaybackRate = function (clock) {
    if (this._lastPlaybackRate === clock.multiplier) {
      return;
    }

    var element = this._element;
    try {
      element.playbackRate = clock.multiplier;
    } catch (error) {
      // Seek manually for unsupported playbackRates.
      element.playbackRate = 0.0;
    }
    this._lastPlaybackRate = clock.multiplier;
  };

  VideoSynchronizer.prototype._onTick = function (clock) {
    var element = this._element;
    if (!defined(element) || element.readyState < 2) {
      return;
    }

    var paused = element.paused;
    var shouldAnimate = clock.shouldAnimate;
    if (shouldAnimate === paused) {
      if (shouldAnimate) {
        element.play();
      } else {
        element.pause();
      }
    }

    //We need to avoid constant seeking or the video will
    //never contain a complete frame for us to render.
    //So don't do anything if we're seeing or on the first
    //tick after a seek (the latter of which allows the frame
    //to actually be rendered.
    if (this._seeking || this._firstTickAfterSeek) {
      this._firstTickAfterSeek = false;
      return;
    }

    this._trySetPlaybackRate(clock);

    var clockTime = clock.currentTime;
    var epoch = defaultValue(this.epoch, Iso8601.MINIMUM_VALUE);
    var videoTime = JulianDate.secondsDifference(clockTime, epoch);

    var duration = element.duration;
    var desiredTime;
    var currentTime = element.currentTime;
    if (element.loop) {
      videoTime = videoTime % duration;
      if (videoTime < 0.0) {
        videoTime = duration - videoTime;
      }
      desiredTime = videoTime;
    } else if (videoTime > duration) {
      desiredTime = duration;
    } else if (videoTime < 0.0) {
      desiredTime = 0.0;
    } else {
      desiredTime = videoTime;
    }

    //If the playing video's time and the scene's clock time
    //ever drift too far apart, we want to set the video to match
    var tolerance = shouldAnimate ? defaultValue(this.tolerance, 1.0) : 0.001;
    if (Math.abs(desiredTime - currentTime) > tolerance) {
      this._seeking = true;
      element.currentTime = desiredTime;
    }
  };

  function createSeekFunction(that) {
    return function () {
      that._seeking = false;
      that._firstTickAfterSeek = true;
    };
  }

  /**
   * @private
   */
  var WallGeometryLibrary = {};

  function latLonEquals(c0, c1) {
    return (
      CesiumMath.equalsEpsilon(c0.latitude, c1.latitude, CesiumMath.EPSILON10) &&
      CesiumMath.equalsEpsilon(c0.longitude, c1.longitude, CesiumMath.EPSILON10)
    );
  }

  var scratchCartographic1$2 = new Cartographic();
  var scratchCartographic2$1 = new Cartographic();
  function removeDuplicates(ellipsoid, positions, topHeights, bottomHeights) {
    positions = arrayRemoveDuplicates(positions, Cartesian3.equalsEpsilon);

    var length = positions.length;
    if (length < 2) {
      return;
    }

    var hasBottomHeights = defined(bottomHeights);
    var hasTopHeights = defined(topHeights);

    var cleanedPositions = new Array(length);
    var cleanedTopHeights = new Array(length);
    var cleanedBottomHeights = new Array(length);

    var v0 = positions[0];
    cleanedPositions[0] = v0;

    var c0 = ellipsoid.cartesianToCartographic(v0, scratchCartographic1$2);
    if (hasTopHeights) {
      c0.height = topHeights[0];
    }

    cleanedTopHeights[0] = c0.height;

    if (hasBottomHeights) {
      cleanedBottomHeights[0] = bottomHeights[0];
    } else {
      cleanedBottomHeights[0] = 0.0;
    }

    var startTopHeight = cleanedTopHeights[0];
    var startBottomHeight = cleanedBottomHeights[0];
    var hasAllSameHeights = startTopHeight === startBottomHeight;

    var index = 1;
    for (var i = 1; i < length; ++i) {
      var v1 = positions[i];
      var c1 = ellipsoid.cartesianToCartographic(v1, scratchCartographic2$1);
      if (hasTopHeights) {
        c1.height = topHeights[i];
      }
      hasAllSameHeights = hasAllSameHeights && c1.height === 0;

      if (!latLonEquals(c0, c1)) {
        cleanedPositions[index] = v1; // Shallow copy!
        cleanedTopHeights[index] = c1.height;

        if (hasBottomHeights) {
          cleanedBottomHeights[index] = bottomHeights[i];
        } else {
          cleanedBottomHeights[index] = 0.0;
        }
        hasAllSameHeights =
          hasAllSameHeights &&
          cleanedTopHeights[index] === cleanedBottomHeights[index];

        Cartographic.clone(c1, c0);
        ++index;
      } else if (c0.height < c1.height) {
        // two adjacent positions are the same, so use whichever has the greater height
        cleanedTopHeights[index - 1] = c1.height;
      }
    }

    if (hasAllSameHeights || index < 2) {
      return;
    }

    cleanedPositions.length = index;
    cleanedTopHeights.length = index;
    cleanedBottomHeights.length = index;

    return {
      positions: cleanedPositions,
      topHeights: cleanedTopHeights,
      bottomHeights: cleanedBottomHeights,
    };
  }

  var positionsArrayScratch = new Array(2);
  var heightsArrayScratch = new Array(2);
  var generateArcOptionsScratch$1 = {
    positions: undefined,
    height: undefined,
    granularity: undefined,
    ellipsoid: undefined,
  };

  /**
   * @private
   */
  WallGeometryLibrary.computePositions = function (
    ellipsoid,
    wallPositions,
    maximumHeights,
    minimumHeights,
    granularity,
    duplicateCorners
  ) {
    var o = removeDuplicates(
      ellipsoid,
      wallPositions,
      maximumHeights,
      minimumHeights
    );

    if (!defined(o)) {
      return;
    }

    wallPositions = o.positions;
    maximumHeights = o.topHeights;
    minimumHeights = o.bottomHeights;

    var length = wallPositions.length;
    var numCorners = length - 2;
    var topPositions;
    var bottomPositions;

    var minDistance = CesiumMath.chordLength(
      granularity,
      ellipsoid.maximumRadius
    );

    var generateArcOptions = generateArcOptionsScratch$1;
    generateArcOptions.minDistance = minDistance;
    generateArcOptions.ellipsoid = ellipsoid;

    if (duplicateCorners) {
      var count = 0;
      var i;

      for (i = 0; i < length - 1; i++) {
        count +=
          PolylinePipeline.numberOfPoints(
            wallPositions[i],
            wallPositions[i + 1],
            minDistance
          ) + 1;
      }

      topPositions = new Float64Array(count * 3);
      bottomPositions = new Float64Array(count * 3);

      var generateArcPositions = positionsArrayScratch;
      var generateArcHeights = heightsArrayScratch;
      generateArcOptions.positions = generateArcPositions;
      generateArcOptions.height = generateArcHeights;

      var offset = 0;
      for (i = 0; i < length - 1; i++) {
        generateArcPositions[0] = wallPositions[i];
        generateArcPositions[1] = wallPositions[i + 1];

        generateArcHeights[0] = maximumHeights[i];
        generateArcHeights[1] = maximumHeights[i + 1];

        var pos = PolylinePipeline.generateArc(generateArcOptions);
        topPositions.set(pos, offset);

        generateArcHeights[0] = minimumHeights[i];
        generateArcHeights[1] = minimumHeights[i + 1];

        bottomPositions.set(
          PolylinePipeline.generateArc(generateArcOptions),
          offset
        );

        offset += pos.length;
      }
    } else {
      generateArcOptions.positions = wallPositions;
      generateArcOptions.height = maximumHeights;
      topPositions = new Float64Array(
        PolylinePipeline.generateArc(generateArcOptions)
      );

      generateArcOptions.height = minimumHeights;
      bottomPositions = new Float64Array(
        PolylinePipeline.generateArc(generateArcOptions)
      );
    }

    return {
      bottomPositions: bottomPositions,
      topPositions: topPositions,
      numCorners: numCorners,
    };
  };

  var scratchCartesian3Position1 = new Cartesian3();
  var scratchCartesian3Position2 = new Cartesian3();
  var scratchCartesian3Position4 = new Cartesian3();
  var scratchCartesian3Position5 = new Cartesian3();
  var scratchBitangent$4 = new Cartesian3();
  var scratchTangent$4 = new Cartesian3();
  var scratchNormal$6 = new Cartesian3();

  /**
   * A description of a wall, which is similar to a KML line string. A wall is defined by a series of points,
   * which extrude down to the ground. Optionally, they can extrude downwards to a specified height.
   *
   * @alias WallGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of Cartesian objects, which are the points of the wall.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number[]} [options.maximumHeights] An array parallel to <code>positions</code> that give the maximum height of the
   *        wall at <code>positions</code>. If undefined, the height of each position in used.
   * @param {Number[]} [options.minimumHeights] An array parallel to <code>positions</code> that give the minimum height of the
   *        wall at <code>positions</code>. If undefined, the height at each position is 0.0.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid for coordinate manipulation
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   *
   * @exception {DeveloperError} positions length must be greater than or equal to 2.
   * @exception {DeveloperError} positions and maximumHeights must have the same length.
   * @exception {DeveloperError} positions and minimumHeights must have the same length.
   *
   * @see WallGeometry#createGeometry
   * @see WallGeometry#fromConstantHeight
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Wall.html|Cesium Sandcastle Wall Demo}
   *
   * @example
   * // create a wall that spans from ground level to 10000 meters
   * var wall = new Cesium.WallGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArrayHeights([
   *     19.0, 47.0, 10000.0,
   *     19.0, 48.0, 10000.0,
   *     20.0, 48.0, 10000.0,
   *     20.0, 47.0, 10000.0,
   *     19.0, 47.0, 10000.0
   *   ])
   * });
   * var geometry = Cesium.WallGeometry.createGeometry(wall);
   */
  function WallGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var wallPositions = options.positions;
    var maximumHeights = options.maximumHeights;
    var minimumHeights = options.minimumHeights;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(wallPositions)) {
      throw new DeveloperError("options.positions is required.");
    }
    if (
      defined(maximumHeights) &&
      maximumHeights.length !== wallPositions.length
    ) {
      throw new DeveloperError(
        "options.positions and options.maximumHeights must have the same length."
      );
    }
    if (
      defined(minimumHeights) &&
      minimumHeights.length !== wallPositions.length
    ) {
      throw new DeveloperError(
        "options.positions and options.minimumHeights must have the same length."
      );
    }
    //>>includeEnd('debug');

    var vertexFormat = defaultValue(options.vertexFormat, VertexFormat.DEFAULT);
    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    this._positions = wallPositions;
    this._minimumHeights = minimumHeights;
    this._maximumHeights = maximumHeights;
    this._vertexFormat = VertexFormat.clone(vertexFormat);
    this._granularity = granularity;
    this._ellipsoid = Ellipsoid.clone(ellipsoid);
    this._workerName = "createWallGeometry";

    var numComponents = 1 + wallPositions.length * Cartesian3.packedLength + 2;
    if (defined(minimumHeights)) {
      numComponents += minimumHeights.length;
    }
    if (defined(maximumHeights)) {
      numComponents += maximumHeights.length;
    }

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength =
      numComponents + Ellipsoid.packedLength + VertexFormat.packedLength + 1;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {WallGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  WallGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    var minimumHeights = value._minimumHeights;
    length = defined(minimumHeights) ? minimumHeights.length : 0;
    array[startingIndex++] = length;

    if (defined(minimumHeights)) {
      for (i = 0; i < length; ++i) {
        array[startingIndex++] = minimumHeights[i];
      }
    }

    var maximumHeights = value._maximumHeights;
    length = defined(maximumHeights) ? maximumHeights.length : 0;
    array[startingIndex++] = length;

    if (defined(maximumHeights)) {
      for (i = 0; i < length; ++i) {
        array[startingIndex++] = maximumHeights[i];
      }
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    VertexFormat.pack(value._vertexFormat, array, startingIndex);
    startingIndex += VertexFormat.packedLength;

    array[startingIndex] = value._granularity;

    return array;
  };

  var scratchEllipsoid$c = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchVertexFormat$c = new VertexFormat();
  var scratchOptions$m = {
    positions: undefined,
    minimumHeights: undefined,
    maximumHeights: undefined,
    ellipsoid: scratchEllipsoid$c,
    vertexFormat: scratchVertexFormat$c,
    granularity: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {WallGeometry} [result] The object into which to store the result.
   * @returns {WallGeometry} The modified result parameter or a new WallGeometry instance if one was not provided.
   */
  WallGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    length = array[startingIndex++];
    var minimumHeights;

    if (length > 0) {
      minimumHeights = new Array(length);
      for (i = 0; i < length; ++i) {
        minimumHeights[i] = array[startingIndex++];
      }
    }

    length = array[startingIndex++];
    var maximumHeights;

    if (length > 0) {
      maximumHeights = new Array(length);
      for (i = 0; i < length; ++i) {
        maximumHeights[i] = array[startingIndex++];
      }
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$c);
    startingIndex += Ellipsoid.packedLength;

    var vertexFormat = VertexFormat.unpack(
      array,
      startingIndex,
      scratchVertexFormat$c
    );
    startingIndex += VertexFormat.packedLength;

    var granularity = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$m.positions = positions;
      scratchOptions$m.minimumHeights = minimumHeights;
      scratchOptions$m.maximumHeights = maximumHeights;
      scratchOptions$m.granularity = granularity;
      return new WallGeometry(scratchOptions$m);
    }

    result._positions = positions;
    result._minimumHeights = minimumHeights;
    result._maximumHeights = maximumHeights;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._vertexFormat = VertexFormat.clone(vertexFormat, result._vertexFormat);
    result._granularity = granularity;

    return result;
  };

  /**
   * A description of a wall, which is similar to a KML line string. A wall is defined by a series of points,
   * which extrude down to the ground. Optionally, they can extrude downwards to a specified height.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of Cartesian objects, which are the points of the wall.
   * @param {Number} [options.maximumHeight] A constant that defines the maximum height of the
   *        wall at <code>positions</code>. If undefined, the height of each position in used.
   * @param {Number} [options.minimumHeight] A constant that defines the minimum height of the
   *        wall at <code>positions</code>. If undefined, the height at each position is 0.0.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid for coordinate manipulation
   * @param {VertexFormat} [options.vertexFormat=VertexFormat.DEFAULT] The vertex attributes to be computed.
   * @returns {WallGeometry}
   *
   *
   * @example
   * // create a wall that spans from 10000 meters to 20000 meters
   * var wall = Cesium.WallGeometry.fromConstantHeights({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     19.0, 47.0,
   *     19.0, 48.0,
   *     20.0, 48.0,
   *     20.0, 47.0,
   *     19.0, 47.0,
   *   ]),
   *   minimumHeight : 20000.0,
   *   maximumHeight : 10000.0
   * });
   * var geometry = Cesium.WallGeometry.createGeometry(wall);
   *
   * @see WallGeometry#createGeometry
   */
  WallGeometry.fromConstantHeights = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions)) {
      throw new DeveloperError("options.positions is required.");
    }
    //>>includeEnd('debug');

    var minHeights;
    var maxHeights;

    var min = options.minimumHeight;
    var max = options.maximumHeight;

    var doMin = defined(min);
    var doMax = defined(max);
    if (doMin || doMax) {
      var length = positions.length;
      minHeights = doMin ? new Array(length) : undefined;
      maxHeights = doMax ? new Array(length) : undefined;

      for (var i = 0; i < length; ++i) {
        if (doMin) {
          minHeights[i] = min;
        }

        if (doMax) {
          maxHeights[i] = max;
        }
      }
    }

    var newOptions = {
      positions: positions,
      maximumHeights: maxHeights,
      minimumHeights: minHeights,
      ellipsoid: options.ellipsoid,
      vertexFormat: options.vertexFormat,
    };
    return new WallGeometry(newOptions);
  };

  /**
   * Computes the geometric representation of a wall, including its vertices, indices, and a bounding sphere.
   *
   * @param {WallGeometry} wallGeometry A description of the wall.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  WallGeometry.createGeometry = function (wallGeometry) {
    var wallPositions = wallGeometry._positions;
    var minimumHeights = wallGeometry._minimumHeights;
    var maximumHeights = wallGeometry._maximumHeights;
    var vertexFormat = wallGeometry._vertexFormat;
    var granularity = wallGeometry._granularity;
    var ellipsoid = wallGeometry._ellipsoid;

    var pos = WallGeometryLibrary.computePositions(
      ellipsoid,
      wallPositions,
      maximumHeights,
      minimumHeights,
      granularity,
      true
    );
    if (!defined(pos)) {
      return;
    }

    var bottomPositions = pos.bottomPositions;
    var topPositions = pos.topPositions;
    var numCorners = pos.numCorners;

    var length = topPositions.length;
    var size = length * 2;

    var positions = vertexFormat.position ? new Float64Array(size) : undefined;
    var normals = vertexFormat.normal ? new Float32Array(size) : undefined;
    var tangents = vertexFormat.tangent ? new Float32Array(size) : undefined;
    var bitangents = vertexFormat.bitangent ? new Float32Array(size) : undefined;
    var textureCoordinates = vertexFormat.st
      ? new Float32Array((size / 3) * 2)
      : undefined;

    var positionIndex = 0;
    var normalIndex = 0;
    var bitangentIndex = 0;
    var tangentIndex = 0;
    var stIndex = 0;

    // add lower and upper points one after the other, lower
    // points being even and upper points being odd
    var normal = scratchNormal$6;
    var tangent = scratchTangent$4;
    var bitangent = scratchBitangent$4;
    var recomputeNormal = true;
    length /= 3;
    var i;
    var s = 0;
    var ds = 1 / (length - numCorners - 1);
    for (i = 0; i < length; ++i) {
      var i3 = i * 3;
      var topPosition = Cartesian3.fromArray(
        topPositions,
        i3,
        scratchCartesian3Position1
      );
      var bottomPosition = Cartesian3.fromArray(
        bottomPositions,
        i3,
        scratchCartesian3Position2
      );
      if (vertexFormat.position) {
        // insert the lower point
        positions[positionIndex++] = bottomPosition.x;
        positions[positionIndex++] = bottomPosition.y;
        positions[positionIndex++] = bottomPosition.z;

        // insert the upper point
        positions[positionIndex++] = topPosition.x;
        positions[positionIndex++] = topPosition.y;
        positions[positionIndex++] = topPosition.z;
      }

      if (vertexFormat.st) {
        textureCoordinates[stIndex++] = s;
        textureCoordinates[stIndex++] = 0.0;

        textureCoordinates[stIndex++] = s;
        textureCoordinates[stIndex++] = 1.0;
      }

      if (vertexFormat.normal || vertexFormat.tangent || vertexFormat.bitangent) {
        var nextTop = Cartesian3.clone(
          Cartesian3.ZERO,
          scratchCartesian3Position5
        );
        var groundPosition = Cartesian3.subtract(
          topPosition,
          ellipsoid.geodeticSurfaceNormal(
            topPosition,
            scratchCartesian3Position2
          ),
          scratchCartesian3Position2
        );
        if (i + 1 < length) {
          nextTop = Cartesian3.fromArray(
            topPositions,
            i3 + 3,
            scratchCartesian3Position5
          );
        }

        if (recomputeNormal) {
          var scalednextPosition = Cartesian3.subtract(
            nextTop,
            topPosition,
            scratchCartesian3Position4
          );
          var scaledGroundPosition = Cartesian3.subtract(
            groundPosition,
            topPosition,
            scratchCartesian3Position1
          );
          normal = Cartesian3.normalize(
            Cartesian3.cross(scaledGroundPosition, scalednextPosition, normal),
            normal
          );
          recomputeNormal = false;
        }

        if (
          Cartesian3.equalsEpsilon(topPosition, nextTop, CesiumMath.EPSILON10)
        ) {
          recomputeNormal = true;
        } else {
          s += ds;
          if (vertexFormat.tangent) {
            tangent = Cartesian3.normalize(
              Cartesian3.subtract(nextTop, topPosition, tangent),
              tangent
            );
          }
          if (vertexFormat.bitangent) {
            bitangent = Cartesian3.normalize(
              Cartesian3.cross(normal, tangent, bitangent),
              bitangent
            );
          }
        }

        if (vertexFormat.normal) {
          normals[normalIndex++] = normal.x;
          normals[normalIndex++] = normal.y;
          normals[normalIndex++] = normal.z;

          normals[normalIndex++] = normal.x;
          normals[normalIndex++] = normal.y;
          normals[normalIndex++] = normal.z;
        }

        if (vertexFormat.tangent) {
          tangents[tangentIndex++] = tangent.x;
          tangents[tangentIndex++] = tangent.y;
          tangents[tangentIndex++] = tangent.z;

          tangents[tangentIndex++] = tangent.x;
          tangents[tangentIndex++] = tangent.y;
          tangents[tangentIndex++] = tangent.z;
        }

        if (vertexFormat.bitangent) {
          bitangents[bitangentIndex++] = bitangent.x;
          bitangents[bitangentIndex++] = bitangent.y;
          bitangents[bitangentIndex++] = bitangent.z;

          bitangents[bitangentIndex++] = bitangent.x;
          bitangents[bitangentIndex++] = bitangent.y;
          bitangents[bitangentIndex++] = bitangent.z;
        }
      }
    }

    var attributes = new GeometryAttributes();

    if (vertexFormat.position) {
      attributes.position = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      });
    }

    if (vertexFormat.normal) {
      attributes.normal = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: normals,
      });
    }

    if (vertexFormat.tangent) {
      attributes.tangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: tangents,
      });
    }

    if (vertexFormat.bitangent) {
      attributes.bitangent = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
        values: bitangents,
      });
    }

    if (vertexFormat.st) {
      attributes.st = new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
        values: textureCoordinates,
      });
    }

    // prepare the side walls, two triangles for each wall
    //
    //    A (i+1)  B (i+3) E
    //    +--------+-------+
    //    |      / |      /|    triangles:  A C B
    //    |     /  |     / |                B C D
    //    |    /   |    /  |
    //    |   /    |   /   |
    //    |  /     |  /    |
    //    | /      | /     |
    //    +--------+-------+
    //    C (i)    D (i+2) F
    //

    var numVertices = size / 3;
    size -= 6 * (numCorners + 1);
    var indices = IndexDatatype$1.createTypedArray(numVertices, size);

    var edgeIndex = 0;
    for (i = 0; i < numVertices - 2; i += 2) {
      var LL = i;
      var LR = i + 2;
      var pl = Cartesian3.fromArray(
        positions,
        LL * 3,
        scratchCartesian3Position1
      );
      var pr = Cartesian3.fromArray(
        positions,
        LR * 3,
        scratchCartesian3Position2
      );
      if (Cartesian3.equalsEpsilon(pl, pr, CesiumMath.EPSILON10)) {
        continue;
      }
      var UL = i + 1;
      var UR = i + 3;

      indices[edgeIndex++] = UL;
      indices[edgeIndex++] = LL;
      indices[edgeIndex++] = UR;
      indices[edgeIndex++] = UR;
      indices[edgeIndex++] = LL;
      indices[edgeIndex++] = LR;
    }

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingSphere: new BoundingSphere.fromVertices(positions),
    });
  };

  var scratchCartesian3Position1$1 = new Cartesian3();
  var scratchCartesian3Position2$1 = new Cartesian3();

  /**
   * A description of a wall outline. A wall is defined by a series of points,
   * which extrude down to the ground. Optionally, they can extrude downwards to a specified height.
   *
   * @alias WallOutlineGeometry
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of Cartesian objects, which are the points of the wall.
   * @param {Number} [options.granularity=CesiumMath.RADIANS_PER_DEGREE] The distance, in radians, between each latitude and longitude. Determines the number of positions in the buffer.
   * @param {Number[]} [options.maximumHeights] An array parallel to <code>positions</code> that give the maximum height of the
   *        wall at <code>positions</code>. If undefined, the height of each position in used.
   * @param {Number[]} [options.minimumHeights] An array parallel to <code>positions</code> that give the minimum height of the
   *        wall at <code>positions</code>. If undefined, the height at each position is 0.0.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid for coordinate manipulation
   *
   * @exception {DeveloperError} positions length must be greater than or equal to 2.
   * @exception {DeveloperError} positions and maximumHeights must have the same length.
   * @exception {DeveloperError} positions and minimumHeights must have the same length.
   *
   * @see WallGeometry#createGeometry
   * @see WallGeometry#fromConstantHeight
   *
   * @example
   * // create a wall outline that spans from ground level to 10000 meters
   * var wall = new Cesium.WallOutlineGeometry({
   *   positions : Cesium.Cartesian3.fromDegreesArrayHeights([
   *     19.0, 47.0, 10000.0,
   *     19.0, 48.0, 10000.0,
   *     20.0, 48.0, 10000.0,
   *     20.0, 47.0, 10000.0,
   *     19.0, 47.0, 10000.0
   *   ])
   * });
   * var geometry = Cesium.WallOutlineGeometry.createGeometry(wall);
   */
  function WallOutlineGeometry(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var wallPositions = options.positions;
    var maximumHeights = options.maximumHeights;
    var minimumHeights = options.minimumHeights;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(wallPositions)) {
      throw new DeveloperError("options.positions is required.");
    }
    if (
      defined(maximumHeights) &&
      maximumHeights.length !== wallPositions.length
    ) {
      throw new DeveloperError(
        "options.positions and options.maximumHeights must have the same length."
      );
    }
    if (
      defined(minimumHeights) &&
      minimumHeights.length !== wallPositions.length
    ) {
      throw new DeveloperError(
        "options.positions and options.minimumHeights must have the same length."
      );
    }
    //>>includeEnd('debug');

    var granularity = defaultValue(
      options.granularity,
      CesiumMath.RADIANS_PER_DEGREE
    );
    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    this._positions = wallPositions;
    this._minimumHeights = minimumHeights;
    this._maximumHeights = maximumHeights;
    this._granularity = granularity;
    this._ellipsoid = Ellipsoid.clone(ellipsoid);
    this._workerName = "createWallOutlineGeometry";

    var numComponents = 1 + wallPositions.length * Cartesian3.packedLength + 2;
    if (defined(minimumHeights)) {
      numComponents += minimumHeights.length;
    }
    if (defined(maximumHeights)) {
      numComponents += maximumHeights.length;
    }

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    this.packedLength = numComponents + Ellipsoid.packedLength + 1;
  }

  /**
   * Stores the provided instance into the provided array.
   *
   * @param {WallOutlineGeometry} value The value to pack.
   * @param {Number[]} array The array to pack into.
   * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
   *
   * @returns {Number[]} The array that was packed into
   */
  WallOutlineGeometry.pack = function (value, array, startingIndex) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required");
    }
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var positions = value._positions;
    var length = positions.length;
    array[startingIndex++] = length;

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      Cartesian3.pack(positions[i], array, startingIndex);
    }

    var minimumHeights = value._minimumHeights;
    length = defined(minimumHeights) ? minimumHeights.length : 0;
    array[startingIndex++] = length;

    if (defined(minimumHeights)) {
      for (i = 0; i < length; ++i) {
        array[startingIndex++] = minimumHeights[i];
      }
    }

    var maximumHeights = value._maximumHeights;
    length = defined(maximumHeights) ? maximumHeights.length : 0;
    array[startingIndex++] = length;

    if (defined(maximumHeights)) {
      for (i = 0; i < length; ++i) {
        array[startingIndex++] = maximumHeights[i];
      }
    }

    Ellipsoid.pack(value._ellipsoid, array, startingIndex);
    startingIndex += Ellipsoid.packedLength;

    array[startingIndex] = value._granularity;

    return array;
  };

  var scratchEllipsoid$d = Ellipsoid.clone(Ellipsoid.UNIT_SPHERE);
  var scratchOptions$n = {
    positions: undefined,
    minimumHeights: undefined,
    maximumHeights: undefined,
    ellipsoid: scratchEllipsoid$d,
    granularity: undefined,
  };

  /**
   * Retrieves an instance from a packed array.
   *
   * @param {Number[]} array The packed array.
   * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
   * @param {WallOutlineGeometry} [result] The object into which to store the result.
   * @returns {WallOutlineGeometry} The modified result parameter or a new WallOutlineGeometry instance if one was not provided.
   */
  WallOutlineGeometry.unpack = function (array, startingIndex, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required");
    }
    //>>includeEnd('debug');

    startingIndex = defaultValue(startingIndex, 0);

    var i;

    var length = array[startingIndex++];
    var positions = new Array(length);

    for (i = 0; i < length; ++i, startingIndex += Cartesian3.packedLength) {
      positions[i] = Cartesian3.unpack(array, startingIndex);
    }

    length = array[startingIndex++];
    var minimumHeights;

    if (length > 0) {
      minimumHeights = new Array(length);
      for (i = 0; i < length; ++i) {
        minimumHeights[i] = array[startingIndex++];
      }
    }

    length = array[startingIndex++];
    var maximumHeights;

    if (length > 0) {
      maximumHeights = new Array(length);
      for (i = 0; i < length; ++i) {
        maximumHeights[i] = array[startingIndex++];
      }
    }

    var ellipsoid = Ellipsoid.unpack(array, startingIndex, scratchEllipsoid$d);
    startingIndex += Ellipsoid.packedLength;

    var granularity = array[startingIndex];

    if (!defined(result)) {
      scratchOptions$n.positions = positions;
      scratchOptions$n.minimumHeights = minimumHeights;
      scratchOptions$n.maximumHeights = maximumHeights;
      scratchOptions$n.granularity = granularity;
      return new WallOutlineGeometry(scratchOptions$n);
    }

    result._positions = positions;
    result._minimumHeights = minimumHeights;
    result._maximumHeights = maximumHeights;
    result._ellipsoid = Ellipsoid.clone(ellipsoid, result._ellipsoid);
    result._granularity = granularity;

    return result;
  };

  /**
   * A description of a walloutline. A wall is defined by a series of points,
   * which extrude down to the ground. Optionally, they can extrude downwards to a specified height.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3[]} options.positions An array of Cartesian objects, which are the points of the wall.
   * @param {Number} [options.maximumHeight] A constant that defines the maximum height of the
   *        wall at <code>positions</code>. If undefined, the height of each position in used.
   * @param {Number} [options.minimumHeight] A constant that defines the minimum height of the
   *        wall at <code>positions</code>. If undefined, the height at each position is 0.0.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid for coordinate manipulation
   * @returns {WallOutlineGeometry}
   *
   *
   * @example
   * // create a wall that spans from 10000 meters to 20000 meters
   * var wall = Cesium.WallOutlineGeometry.fromConstantHeights({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     19.0, 47.0,
   *     19.0, 48.0,
   *     20.0, 48.0,
   *     20.0, 47.0,
   *     19.0, 47.0,
   *   ]),
   *   minimumHeight : 20000.0,
   *   maximumHeight : 10000.0
   * });
   * var geometry = Cesium.WallOutlineGeometry.createGeometry(wall);
   *
   * @see WallOutlineGeometry#createGeometry
   */
  WallOutlineGeometry.fromConstantHeights = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var positions = options.positions;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(positions)) {
      throw new DeveloperError("options.positions is required.");
    }
    //>>includeEnd('debug');

    var minHeights;
    var maxHeights;

    var min = options.minimumHeight;
    var max = options.maximumHeight;

    var doMin = defined(min);
    var doMax = defined(max);
    if (doMin || doMax) {
      var length = positions.length;
      minHeights = doMin ? new Array(length) : undefined;
      maxHeights = doMax ? new Array(length) : undefined;

      for (var i = 0; i < length; ++i) {
        if (doMin) {
          minHeights[i] = min;
        }

        if (doMax) {
          maxHeights[i] = max;
        }
      }
    }

    var newOptions = {
      positions: positions,
      maximumHeights: maxHeights,
      minimumHeights: minHeights,
      ellipsoid: options.ellipsoid,
    };
    return new WallOutlineGeometry(newOptions);
  };

  /**
   * Computes the geometric representation of a wall outline, including its vertices, indices, and a bounding sphere.
   *
   * @param {WallOutlineGeometry} wallGeometry A description of the wall outline.
   * @returns {Geometry|undefined} The computed vertices and indices.
   */
  WallOutlineGeometry.createGeometry = function (wallGeometry) {
    var wallPositions = wallGeometry._positions;
    var minimumHeights = wallGeometry._minimumHeights;
    var maximumHeights = wallGeometry._maximumHeights;
    var granularity = wallGeometry._granularity;
    var ellipsoid = wallGeometry._ellipsoid;

    var pos = WallGeometryLibrary.computePositions(
      ellipsoid,
      wallPositions,
      maximumHeights,
      minimumHeights,
      granularity,
      false
    );
    if (!defined(pos)) {
      return;
    }

    var bottomPositions = pos.bottomPositions;
    var topPositions = pos.topPositions;

    var length = topPositions.length;
    var size = length * 2;

    var positions = new Float64Array(size);
    var positionIndex = 0;

    // add lower and upper points one after the other, lower
    // points being even and upper points being odd
    length /= 3;
    var i;
    for (i = 0; i < length; ++i) {
      var i3 = i * 3;
      var topPosition = Cartesian3.fromArray(
        topPositions,
        i3,
        scratchCartesian3Position1$1
      );
      var bottomPosition = Cartesian3.fromArray(
        bottomPositions,
        i3,
        scratchCartesian3Position2$1
      );

      // insert the lower point
      positions[positionIndex++] = bottomPosition.x;
      positions[positionIndex++] = bottomPosition.y;
      positions[positionIndex++] = bottomPosition.z;

      // insert the upper point
      positions[positionIndex++] = topPosition.x;
      positions[positionIndex++] = topPosition.y;
      positions[positionIndex++] = topPosition.z;
    }

    var attributes = new GeometryAttributes({
      position: new GeometryAttribute({
        componentDatatype: ComponentDatatype$1.DOUBLE,
        componentsPerAttribute: 3,
        values: positions,
      }),
    });

    var numVertices = size / 3;
    size = 2 * numVertices - 4 + numVertices;
    var indices = IndexDatatype$1.createTypedArray(numVertices, size);

    var edgeIndex = 0;
    for (i = 0; i < numVertices - 2; i += 2) {
      var LL = i;
      var LR = i + 2;
      var pl = Cartesian3.fromArray(
        positions,
        LL * 3,
        scratchCartesian3Position1$1
      );
      var pr = Cartesian3.fromArray(
        positions,
        LR * 3,
        scratchCartesian3Position2$1
      );
      if (Cartesian3.equalsEpsilon(pl, pr, CesiumMath.EPSILON10)) {
        continue;
      }
      var UL = i + 1;
      var UR = i + 3;

      indices[edgeIndex++] = UL;
      indices[edgeIndex++] = LL;
      indices[edgeIndex++] = UL;
      indices[edgeIndex++] = UR;
      indices[edgeIndex++] = LL;
      indices[edgeIndex++] = LR;
    }

    indices[edgeIndex++] = numVertices - 2;
    indices[edgeIndex++] = numVertices - 1;

    return new Geometry({
      attributes: attributes,
      indices: indices,
      primitiveType: PrimitiveType$1.LINES,
      boundingSphere: new BoundingSphere.fromVertices(positions),
    });
  };

  /**
   * A spline that linearly interpolates over an array of weight values used by morph targets.
   *
   * @alias WeightSpline
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Number[]} options.times An array of strictly increasing, unit-less, floating-point times at each point.
   *                The values are in no way connected to the clock time. They are the parameterization for the curve.
   * @param {Number[]} options.weights The array of floating-point control weights given. The weights are ordered such
   *                that all weights for the targets are given in chronological order and order in which they appear in
   *                the glTF from which the morph targets come. This means for 2 targets, weights = [w(0,0), w(0,1), w(1,0), w(1,1) ...]
   *                where i and j in w(i,j) are the time indices and target indices, respectively.
   *
   * @exception {DeveloperError} weights.length must be greater than or equal to 2.
   * @exception {DeveloperError} times.length must be a factor of weights.length.
   *
   *
   * @example
   * var times = [ 0.0, 1.5, 3.0, 4.5, 6.0 ];
   * var weights = [0.0, 1.0, 0.25, 0.75, 0.5, 0.5, 0.75, 0.25, 1.0, 0.0]; //Two targets
   * var spline = new Cesium.WeightSpline({
   *     times : times,
   *     weights : weights
   * });
   *
   * var p0 = spline.evaluate(times[0]);
   *
   * @see LinearSpline
   * @see HermiteSpline
   * @see CatmullRomSpline
   * @see QuaternionSpline
   */
  function WeightSpline(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var weights = options.weights;
    var times = options.times;

    //>>includeStart('debug', pragmas.debug);
    Check.defined("weights", weights);
    Check.defined("times", times);
    Check.typeOf.number.greaterThanOrEquals("weights.length", weights.length, 3);
    if (weights.length % times.length !== 0) {
      throw new DeveloperError(
        "times.length must be a factor of weights.length."
      );
    }
    //>>includeEnd('debug');

    this._times = times;
    this._weights = weights;
    this._count = weights.length / times.length;

    this._lastTimeIndex = 0;
  }

  Object.defineProperties(WeightSpline.prototype, {
    /**
     * An array of times for the control weights.
     *
     * @memberof WeightSpline.prototype
     *
     * @type {Number[]}
     * @readonly
     */
    times: {
      get: function () {
        return this._times;
      },
    },

    /**
     * An array of floating-point array control weights.
     *
     * @memberof WeightSpline.prototype
     *
     * @type {Number[]}
     * @readonly
     */
    weights: {
      get: function () {
        return this._weights;
      },
    },
  });

  /**
   * Finds an index <code>i</code> in <code>times</code> such that the parameter
   * <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
   * @function
   *
   * @param {Number} time The time.
   * @returns {Number} The index for the element at the start of the interval.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  WeightSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;

  /**
   * Wraps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, wrapped around to the updated animation.
   */
  WeightSpline.prototype.wrapTime = Spline.prototype.wrapTime;

  /**
   * Clamps the given time to the period covered by the spline.
   * @function
   *
   * @param {Number} time The time.
   * @return {Number} The time, clamped to the animation period.
   */
  WeightSpline.prototype.clampTime = Spline.prototype.clampTime;

  /**
   * Evaluates the curve at a given time.
   *
   * @param {Number} time The time at which to evaluate the curve.
   * @param {Number[]} [result] The object onto which to store the result.
   * @returns {Number[]} The modified result parameter or a new instance of the point on the curve at the given time.
   *
   * @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
   *                             is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
   *                             in the array <code>times</code>.
   */
  WeightSpline.prototype.evaluate = function (time, result) {
    var weights = this.weights;
    var times = this.times;

    var i = (this._lastTimeIndex = this.findTimeInterval(
      time,
      this._lastTimeIndex
    ));
    var u = (time - times[i]) / (times[i + 1] - times[i]);

    if (!defined(result)) {
      result = new Array(this._count);
    }

    for (var j = 0; j < this._count; j++) {
      var index = i * this._count + j;
      result[j] = weights[index] * (1.0 - u) + weights[index + this._count] * u;
    }

    return result;
  };

  /**
   * Create a shallow copy of an array from begin to end.
   *
   * @param {Array} array The array to fill.
   * @param {Number} [begin=0] The index to start at.
   * @param {Number} [end=array.length] The index to end at which is not included.
   *
   * @returns {Array} The resulting array.
   * @private
   */
  function arraySlice(array, begin, end) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("array", array);
    if (defined(begin)) {
      Check.typeOf.number("begin", begin);
    }
    if (defined(end)) {
      Check.typeOf.number("end", end);
    }
    //>>includeEnd('debug');

    if (typeof array.slice === "function") {
      return array.slice(begin, end);
    }

    var copy = Array.prototype.slice.call(array, begin, end);
    var typedArrayTypes = FeatureDetection.typedArrayTypes;
    var length = typedArrayTypes.length;
    for (var i = 0; i < length; ++i) {
      if (array instanceof typedArrayTypes[i]) {
        copy = new typedArrayTypes[i](copy);
        break;
      }
    }

    return copy;
  }

  var implementation$1;
  if (typeof cancelAnimationFrame !== "undefined") {
    implementation$1 = cancelAnimationFrame;
  }

  (function () {
    // look for vendor prefixed function
    if (!defined(implementation$1) && typeof window !== "undefined") {
      var vendors = ["webkit", "moz", "ms", "o"];
      var i = 0;
      var len = vendors.length;
      while (i < len && !defined(implementation$1)) {
        implementation$1 = window[vendors[i] + "CancelAnimationFrame"];
        if (!defined(implementation$1)) {
          implementation$1 = window[vendors[i] + "CancelRequestAnimationFrame"];
        }
        ++i;
      }
    }

    // otherwise, assume requestAnimationFrame is based on setTimeout, so use clearTimeout
    if (!defined(implementation$1)) {
      implementation$1 = clearTimeout;
    }
  })();

  /**
   * A browser-independent function to cancel an animation frame requested using {@link requestAnimationFrame}.
   *
   * @function cancelAnimationFrame
   *
   * @param {Number} requestID The value returned by {@link requestAnimationFrame}.
   *
   * @see {@link http://www.w3.org/TR/animation-timing/#the-WindowAnimationTiming-interface|The WindowAnimationTiming interface}
   */
  function cancelAnimationFramePolyfill(requestID) {
    // we need this extra wrapper function because the native cancelAnimationFrame
    // functions must be invoked on the global scope (window), which is not the case
    // if invoked as Cesium.cancelAnimationFrame(requestID)
    implementation$1(requestID);
  }

  /**
   * Creates a Globally unique identifier (GUID) string.  A GUID is 128 bits long, and can guarantee uniqueness across space and time.
   *
   * @function
   *
   * @returns {String}
   *
   *
   * @example
   * this.guid = Cesium.createGuid();
   *
   * @see {@link http://www.ietf.org/rfc/rfc4122.txt|RFC 4122 A Universally Unique IDentifier (UUID) URN Namespace}
   */
  function createGuid() {
    // http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript
    return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function (c) {
      var r = (Math.random() * 16) | 0;
      var v = c === "x" ? r : (r & 0x3) | 0x8;
      return v.toString(16);
    });
  }

  /**
   * Creates a {@link CesiumTerrainProvider} instance for the {@link https://cesium.com/content/#cesium-world-terrain|Cesium World Terrain}.
   *
   * @function
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.requestVertexNormals=false] Flag that indicates if the client should request additional lighting information from the server if available.
   * @param {Boolean} [options.requestWaterMask=false] Flag that indicates if the client should request per tile water masks from the server if available.
   * @returns {CesiumTerrainProvider}
   *
   * @see Ion
   *
   * @example
   * // Create Cesium World Terrain with default settings
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *     terrainProvider : Cesium.createWorldTerrain();
   * });
   *
   * @example
   * // Create Cesium World Terrain with water and normals.
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *     terrainProvider : Cesium.createWorldTerrain({
   *         requestWaterMask : true,
   *         requestVertexNormals : true
   *     });
   * });
   *
   */
  function createWorldTerrain(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    return new CesiumTerrainProvider({
      url: IonResource.fromAssetId(1),
      requestVertexNormals: defaultValue(options.requestVertexNormals, false),
      requestWaterMask: defaultValue(options.requestWaterMask, false),
    });
  }

  var compressedMagic = 0x7468dead;
  var compressedMagicSwap = 0xadde6874;

  /**
   * Decodes data that is received from the Google Earth Enterprise server.
   *
   * @param {ArrayBuffer} key The key used during decoding.
   * @param {ArrayBuffer} data The data to be decoded.
   *
   * @private
   */
  function decodeGoogleEarthEnterpriseData(key, data) {
    if (decodeGoogleEarthEnterpriseData.passThroughDataForTesting) {
      return data;
    }

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("key", key);
    Check.typeOf.object("data", data);
    //>>includeEnd('debug');

    var keyLength = key.byteLength;
    if (keyLength === 0 || keyLength % 4 !== 0) {
      throw new RuntimeError(
        "The length of key must be greater than 0 and a multiple of 4."
      );
    }

    var dataView = new DataView(data);
    var magic = dataView.getUint32(0, true);
    if (magic === compressedMagic || magic === compressedMagicSwap) {
      // Occasionally packets don't come back encoded, so just return
      return data;
    }

    var keyView = new DataView(key);

    var dp = 0;
    var dpend = data.byteLength;
    var dpend64 = dpend - (dpend % 8);
    var kpend = keyLength;
    var kp;
    var off = 8;

    // This algorithm is intentionally asymmetric to make it more difficult to
    // guess. Security through obscurity. :-(

    // while we have a full uint64 (8 bytes) left to do
    // assumes buffer is 64bit aligned (or processor doesn't care)
    while (dp < dpend64) {
      // rotate the key each time through by using the offets 16,0,8,16,0,8,...
      off = (off + 8) % 24;
      kp = off;

      // run through one key length xor'ing one uint64 at a time
      // then drop out to rotate the key for the next bit
      while (dp < dpend64 && kp < kpend) {
        dataView.setUint32(
          dp,
          dataView.getUint32(dp, true) ^ keyView.getUint32(kp, true),
          true
        );
        dataView.setUint32(
          dp + 4,
          dataView.getUint32(dp + 4, true) ^ keyView.getUint32(kp + 4, true),
          true
        );
        dp += 8;
        kp += 24;
      }
    }

    // now the remaining 1 to 7 bytes
    if (dp < dpend) {
      if (kp >= kpend) {
        // rotate the key one last time (if necessary)
        off = (off + 8) % 24;
        kp = off;
      }

      while (dp < dpend) {
        dataView.setUint8(dp, dataView.getUint8(dp) ^ keyView.getUint8(kp));
        dp++;
        kp++;
      }
    }
  }

  decodeGoogleEarthEnterpriseData.passThroughDataForTesting = false;

  /**
   * Given a URI, returns the last segment of the URI, removing any path or query information.
   * @function getFilenameFromUri
   *
   * @param {String} uri The Uri.
   * @returns {String} The last segment of the Uri.
   *
   * @example
   * //fileName will be"simple.czml";
   * var fileName = Cesium.getFilenameFromUri('/Gallery/simple.czml?value=true&example=false');
   */
  function getFilenameFromUri(uri) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(uri)) {
      throw new DeveloperError("uri is required.");
    }
    //>>includeEnd('debug');

    var uriObject = new URI(uri);
    uriObject.normalize();
    var path = uriObject.path;
    var index = path.lastIndexOf("/");
    if (index !== -1) {
      path = path.substr(index + 1);
    }
    return path;
  }

  /**
   * @private
   */
  function getMagic(uint8Array, byteOffset) {
    byteOffset = defaultValue(byteOffset, 0);
    return getStringFromTypedArray(
      uint8Array,
      byteOffset,
      Math.min(4, uint8Array.length)
    );
  }

  var transcodeTaskProcessor = new TaskProcessor(
    "transcodeCRNToDXT",
    Number.POSITIVE_INFINITY
  );

  /**
   * Asynchronously loads and parses the given URL to a CRN file or parses the raw binary data of a CRN file.
   * Returns a promise that will resolve to an object containing the image buffer, width, height and format once loaded,
   * or reject if the URL failed to load or failed to parse the data.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   *
   * @function loadCRN
   *
   * @param {Resource|String|ArrayBuffer} resourceOrUrlOrBuffer The URL of the binary data or an ArrayBuffer.
   * @returns {Promise.<CompressedTextureBuffer>|undefined} A promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   * @exception {RuntimeError} Unsupported compressed format.
   *
   * @example
   * // load a single URL asynchronously
   * Cesium.loadCRN('some/url').then(function(textureData) {
   *     var width = textureData.width;
   *     var height = textureData.height;
   *     var format = textureData.internalFormat;
   *     var arrayBufferView = textureData.bufferView;
   *     // use the data to create a texture
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link https://github.com/BinomialLLC/crunch|crunch DXTc texture compression and transcoding library}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  function loadCRN(resourceOrUrlOrBuffer) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(resourceOrUrlOrBuffer)) {
      throw new DeveloperError("resourceOrUrlOrBuffer is required.");
    }
    //>>includeEnd('debug');

    var loadPromise;
    if (
      resourceOrUrlOrBuffer instanceof ArrayBuffer ||
      ArrayBuffer.isView(resourceOrUrlOrBuffer)
    ) {
      loadPromise = when.resolve(resourceOrUrlOrBuffer);
    } else {
      var resource = Resource.createIfNeeded(resourceOrUrlOrBuffer);
      loadPromise = resource.fetchArrayBuffer();
    }

    if (!defined(loadPromise)) {
      return undefined;
    }

    return loadPromise
      .then(function (data) {
        if (!defined(data)) {
          return;
        }
        var transferrableObjects = [];
        if (data instanceof ArrayBuffer) {
          transferrableObjects.push(data);
        } else if (
          data.byteOffset === 0 &&
          data.byteLength === data.buffer.byteLength
        ) {
          transferrableObjects.push(data.buffer);
        } else {
          // data is a view of an array buffer. need to copy so it is transferrable to web worker
          data = data.slice(0, data.length);
          transferrableObjects.push(data.buffer);
        }

        return transcodeTaskProcessor.scheduleTask(data, transferrableObjects);
      })
      .then(function (compressedTextureBuffer) {
        return CompressedTextureBuffer.clone(compressedTextureBuffer);
      });
  }

  /**
   * @private
   */
  function loadImageFromTypedArray(options) {
    var uint8Array = options.uint8Array;
    var format = options.format;
    var request = options.request;
    var flipY = defaultValue(options.flipY, false);
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("uint8Array", uint8Array);
    Check.typeOf.string("format", format);
    //>>includeEnd('debug');

    var blob = new Blob([uint8Array], {
      type: format,
    });

    var blobUrl;
    return Resource.supportsImageBitmapOptions()
      .then(function (result) {
        if (result) {
          return when(
            Resource.createImageBitmapFromBlob(blob, {
              flipY: flipY,
              premultiplyAlpha: false,
            })
          );
        }

        blobUrl = window.URL.createObjectURL(blob);
        var resource = new Resource({
          url: blobUrl,
          request: request,
        });

        return resource.fetchImage({
          flipY: flipY,
        });
      })
      .then(function (result) {
        if (defined(blobUrl)) {
          window.URL.revokeObjectURL(blobUrl);
        }
        return result;
      })
      .otherwise(function (error) {
        if (defined(blobUrl)) {
          window.URL.revokeObjectURL(blobUrl);
        }
        return when.reject(error);
      });
  }

  /**
   * Asynchronously loads and parses the given URL to a KTX file or parses the raw binary data of a KTX file.
   * Returns a promise that will resolve to an object containing the image buffer, width, height and format once loaded,
   * or reject if the URL failed to load or failed to parse the data.  The data is loaded
   * using XMLHttpRequest, which means that in order to make requests to another origin,
   * the server must have Cross-Origin Resource Sharing (CORS) headers enabled.
   * <p>
   * The following are part of the KTX format specification but are not supported:
   * <ul>
   *     <li>Big-endian files</li>
   *     <li>Metadata</li>
   *     <li>3D textures</li>
   *     <li>Texture Arrays</li>
   *     <li>Cubemaps</li>
   *     <li>Mipmaps</li>
   * </ul>
   * </p>
   *
   * @function loadKTX
   *
   * @param {Resource|String|ArrayBuffer} resourceOrUrlOrBuffer The URL of the binary data or an ArrayBuffer.
   * @returns {Promise.<CompressedTextureBuffer>|undefined} A promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
   *
   * @exception {RuntimeError} Invalid KTX file.
   * @exception {RuntimeError} File is the wrong endianness.
   * @exception {RuntimeError} glInternalFormat is not a valid format.
   * @exception {RuntimeError} glType must be zero when the texture is compressed.
   * @exception {RuntimeError} The type size for compressed textures must be 1.
   * @exception {RuntimeError} glFormat must be zero when the texture is compressed.
   * @exception {RuntimeError} Generating mipmaps for a compressed texture is unsupported.
   * @exception {RuntimeError} The base internal format must be the same as the format for uncompressed textures.
   * @exception {RuntimeError} 3D textures are not supported.
   * @exception {RuntimeError} Texture arrays are not supported.
   * @exception {RuntimeError} Cubemaps are not supported.
   *
   * @example
   * // load a single URL asynchronously
   * Cesium.loadKTX('some/url').then(function(ktxData) {
   *     var width = ktxData.width;
   *     var height = ktxData.height;
   *     var format = ktxData.internalFormat;
   *     var arrayBufferView = ktxData.bufferView;
   *     // use the data to create a texture
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link https://www.khronos.org/opengles/sdk/tools/KTX/file_format_spec/|KTX file format}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   */
  function loadKTX(resourceOrUrlOrBuffer) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("resourceOrUrlOrBuffer", resourceOrUrlOrBuffer);
    //>>includeEnd('debug');

    var loadPromise;
    if (
      resourceOrUrlOrBuffer instanceof ArrayBuffer ||
      ArrayBuffer.isView(resourceOrUrlOrBuffer)
    ) {
      loadPromise = when.resolve(resourceOrUrlOrBuffer);
    } else {
      var resource = Resource.createIfNeeded(resourceOrUrlOrBuffer);
      loadPromise = resource.fetchArrayBuffer();
    }

    if (!defined(loadPromise)) {
      return undefined;
    }

    return loadPromise.then(function (data) {
      if (defined(data)) {
        return parseKTX(data);
      }
    });
  }

  var fileIdentifier = [
    0xab,
    0x4b,
    0x54,
    0x58,
    0x20,
    0x31,
    0x31,
    0xbb,
    0x0d,
    0x0a,
    0x1a,
    0x0a,
  ];
  var endiannessTest = 0x04030201;
  var faceOrder = [
    "positiveX",
    "negativeX",
    "positiveY",
    "negativeY",
    "positiveZ",
    "negativeZ",
  ];

  var sizeOfUint32$1 = 4;

  function parseKTX(data) {
    var byteBuffer = new Uint8Array(data);

    var isKTX = true;
    var i;
    for (i = 0; i < fileIdentifier.length; ++i) {
      if (fileIdentifier[i] !== byteBuffer[i]) {
        isKTX = false;
        break;
      }
    }

    if (!isKTX) {
      throw new RuntimeError("Invalid KTX file.");
    }

    var view;
    var byteOffset;

    if (defined(data.buffer)) {
      view = new DataView(data.buffer);
      byteOffset = data.byteOffset;
    } else {
      view = new DataView(data);
      byteOffset = 0;
    }

    byteOffset += 12; // skip identifier

    var endianness = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    if (endianness !== endiannessTest) {
      throw new RuntimeError("File is the wrong endianness.");
    }

    var glType = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var glTypeSize = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var glFormat = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var glInternalFormat = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var glBaseInternalFormat = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var pixelWidth = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var pixelHeight = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var pixelDepth = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var numberOfArrayElements = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var numberOfFaces = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var numberOfMipmapLevels = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;
    var bytesOfKeyValueByteSize = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;

    // skip metadata
    byteOffset += bytesOfKeyValueByteSize;

    var imageSize = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$1;

    var texture;
    if (defined(data.buffer)) {
      texture = new Uint8Array(data.buffer, byteOffset, imageSize);
    } else {
      texture = new Uint8Array(data, byteOffset, imageSize);
    }

    // Some tools use a sized internal format.
    // See table 2: https://www.opengl.org/sdk/docs/man/html/glTexImage2D.xhtml
    if (glInternalFormat === WebGLConstants$1.RGB8) {
      glInternalFormat = PixelFormat$1.RGB;
    } else if (glInternalFormat === WebGLConstants$1.RGBA8) {
      glInternalFormat = PixelFormat$1.RGBA;
    }

    if (!PixelFormat$1.validate(glInternalFormat)) {
      throw new RuntimeError("glInternalFormat is not a valid format.");
    }

    if (PixelFormat$1.isCompressedFormat(glInternalFormat)) {
      if (glType !== 0) {
        throw new RuntimeError(
          "glType must be zero when the texture is compressed."
        );
      }
      if (glTypeSize !== 1) {
        throw new RuntimeError(
          "The type size for compressed textures must be 1."
        );
      }
      if (glFormat !== 0) {
        throw new RuntimeError(
          "glFormat must be zero when the texture is compressed."
        );
      }
    } else if (glType !== WebGLConstants$1.UNSIGNED_BYTE) {
      throw new RuntimeError("Only unsigned byte buffers are supported.");
    } else if (glBaseInternalFormat !== glFormat) {
      throw new RuntimeError(
        "The base internal format must be the same as the format for uncompressed textures."
      );
    }

    if (pixelDepth !== 0) {
      throw new RuntimeError("3D textures are unsupported.");
    }

    if (numberOfArrayElements !== 0) {
      throw new RuntimeError("Texture arrays are unsupported.");
    }

    var offset = texture.byteOffset;
    var mipmaps = new Array(numberOfMipmapLevels);
    for (i = 0; i < numberOfMipmapLevels; ++i) {
      var level = (mipmaps[i] = {});
      for (var j = 0; j < numberOfFaces; ++j) {
        var width = pixelWidth >> i;
        var height = pixelHeight >> i;
        var levelSize = PixelFormat$1.isCompressedFormat(glInternalFormat)
          ? PixelFormat$1.compressedTextureSizeInBytes(
              glInternalFormat,
              width,
              height
            )
          : PixelFormat$1.textureSizeInBytes(
              glInternalFormat,
              glType,
              width,
              height
            );
        var levelBuffer = new Uint8Array(texture.buffer, offset, levelSize);
        level[faceOrder[j]] = new CompressedTextureBuffer(
          glInternalFormat,
          width,
          height,
          levelBuffer
        );
        offset += levelSize;
      }
      offset += 3 - ((offset + 3) % 4) + 4;
    }

    var result = mipmaps;
    if (numberOfFaces === 1) {
      for (i = 0; i < numberOfMipmapLevels; ++i) {
        result[i] = result[i][faceOrder[0]];
      }
    }
    if (numberOfMipmapLevels === 1) {
      result = result[0];
    }

    return result;
  }

  var leftScratchArray = [];
  var rightScratchArray = [];

  function merge(array, compare, userDefinedObject, start, middle, end) {
    var leftLength = middle - start + 1;
    var rightLength = end - middle;

    var left = leftScratchArray;
    var right = rightScratchArray;

    var i;
    var j;

    for (i = 0; i < leftLength; ++i) {
      left[i] = array[start + i];
    }

    for (j = 0; j < rightLength; ++j) {
      right[j] = array[middle + j + 1];
    }

    i = 0;
    j = 0;
    for (var k = start; k <= end; ++k) {
      var leftElement = left[i];
      var rightElement = right[j];
      if (
        i < leftLength &&
        (j >= rightLength ||
          compare(leftElement, rightElement, userDefinedObject) <= 0)
      ) {
        array[k] = leftElement;
        ++i;
      } else if (j < rightLength) {
        array[k] = rightElement;
        ++j;
      }
    }
  }

  function sort(array, compare, userDefinedObject, start, end) {
    if (start >= end) {
      return;
    }

    var middle = Math.floor((start + end) * 0.5);
    sort(array, compare, userDefinedObject, start, middle);
    sort(array, compare, userDefinedObject, middle + 1, end);
    merge(array, compare, userDefinedObject, start, middle, end);
  }

  /**
   * A stable merge sort.
   *
   * @function mergeSort
   * @param {Array} array The array to sort.
   * @param {mergeSortComparator} comparator The function to use to compare elements in the array.
   * @param {*} [userDefinedObject] Any item to pass as the third parameter to <code>comparator</code>.
   *
   * @example
   * // Assume array contains BoundingSpheres in world coordinates.
   * // Sort them in ascending order of distance from the camera.
   * var position = camera.positionWC;
   * Cesium.mergeSort(array, function(a, b, position) {
   *     return Cesium.BoundingSphere.distanceSquaredTo(b, position) - Cesium.BoundingSphere.distanceSquaredTo(a, position);
   * }, position);
   */
  function mergeSort(array, comparator, userDefinedObject) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required.");
    }
    if (!defined(comparator)) {
      throw new DeveloperError("comparator is required.");
    }
    //>>includeEnd('debug');

    var length = array.length;
    var scratchLength = Math.ceil(length * 0.5);

    // preallocate space in scratch arrays
    leftScratchArray.length = scratchLength;
    rightScratchArray.length = scratchLength;

    sort(array, comparator, userDefinedObject, 0, length - 1);

    // trim scratch arrays
    leftScratchArray.length = 0;
    rightScratchArray.length = 0;
  }

  var coords = new Cartesian3();

  /**
   * Determines if a point is inside a triangle.
   *
   * @function pointInsideTriangle
   *
   * @param {Cartesian2|Cartesian3} point The point to test.
   * @param {Cartesian2|Cartesian3} p0 The first point of the triangle.
   * @param {Cartesian2|Cartesian3} p1 The second point of the triangle.
   * @param {Cartesian2|Cartesian3} p2 The third point of the triangle.
   * @returns {Boolean} <code>true</code> if the point is inside the triangle; otherwise, <code>false</code>.
   *
   * @example
   * // Returns true
   * var p = new Cesium.Cartesian2(0.25, 0.25);
   * var b = Cesium.pointInsideTriangle(p,
   *   new Cesium.Cartesian2(0.0, 0.0),
   *   new Cesium.Cartesian2(1.0, 0.0),
   *   new Cesium.Cartesian2(0.0, 1.0));
   */
  function pointInsideTriangle(point, p0, p1, p2) {
    barycentricCoordinates(point, p0, p1, p2, coords);
    return coords.x > 0.0 && coords.y > 0.0 && coords.z > 0;
  }

  var implementation$2;
  if (typeof requestAnimationFrame !== "undefined") {
    implementation$2 = requestAnimationFrame;
  }

  (function () {
    // look for vendor prefixed function
    if (!defined(implementation$2) && typeof window !== "undefined") {
      var vendors = ["webkit", "moz", "ms", "o"];
      var i = 0;
      var len = vendors.length;
      while (i < len && !defined(implementation$2)) {
        implementation$2 = window[vendors[i] + "RequestAnimationFrame"];
        ++i;
      }
    }

    // build an implementation based on setTimeout
    if (!defined(implementation$2)) {
      var msPerFrame = 1000.0 / 60.0;
      var lastFrameTime = 0;
      implementation$2 = function (callback) {
        var currentTime = getTimestamp$1();

        // schedule the callback to target 60fps, 16.7ms per frame,
        // accounting for the time taken by the callback
        var delay = Math.max(msPerFrame - (currentTime - lastFrameTime), 0);
        lastFrameTime = currentTime + delay;

        return setTimeout(function () {
          callback(lastFrameTime);
        }, delay);
      };
    }
  })();

  /**
   * A browser-independent function to request a new animation frame.  This is used to create
   * an application's draw loop as shown in the example below.
   *
   * @function requestAnimationFrame
   *
   * @param {requestAnimationFrameCallback} callback The function to call when the next frame should be drawn.
   * @returns {Number} An ID that can be passed to {@link cancelAnimationFrame} to cancel the request.
   *
   *
   * @example
   * // Create a draw loop using requestAnimationFrame. The
   * // tick callback function is called for every animation frame.
   * function tick() {
   *   scene.render();
   *   Cesium.requestAnimationFrame(tick);
   * }
   * tick();
   *
   * @see {@link https://www.w3.org/TR/html51/webappapis.html#animation-frames|The Web API Animation Frames interface}
   */
  function requestAnimationFramePolyFill(callback) {
    // we need this extra wrapper function because the native requestAnimationFrame
    // functions must be invoked on the global scope (window), which is not the case
    // if invoked as Cesium.requestAnimationFrame(callback)
    return implementation$2(callback);
  }

  /**
   * Initiates a terrain height query for an array of {@link Cartographic} positions by
   * requesting tiles from a terrain provider, sampling, and interpolating.  The interpolation
   * matches the triangles used to render the terrain at the specified level.  The query
   * happens asynchronously, so this function returns a promise that is resolved when
   * the query completes.  Each point height is modified in place.  If a height can not be
   * determined because no terrain data is available for the specified level at that location,
   * or another error occurs, the height is set to undefined.  As is typical of the
   * {@link Cartographic} type, the supplied height is a height above the reference ellipsoid
   * (such as {@link Ellipsoid.WGS84}) rather than an altitude above mean sea level.  In other
   * words, it will not necessarily be 0.0 if sampled in the ocean. This function needs the
   * terrain level of detail as input, if you need to get the altitude of the terrain as precisely
   * as possible (i.e. with maximum level of detail) use {@link sampleTerrainMostDetailed}.
   *
   * @function sampleTerrain
   *
   * @param {TerrainProvider} terrainProvider The terrain provider from which to query heights.
   * @param {Number} level The terrain level-of-detail from which to query terrain heights.
   * @param {Cartographic[]} positions The positions to update with terrain heights.
   * @returns {Promise.<Cartographic[]>} A promise that resolves to the provided list of positions when terrain the query has completed.
   *
   * @see sampleTerrainMostDetailed
   *
   * @example
   * // Query the terrain height of two Cartographic positions
   * var terrainProvider = Cesium.createWorldTerrain();
   * var positions = [
   *     Cesium.Cartographic.fromDegrees(86.925145, 27.988257),
   *     Cesium.Cartographic.fromDegrees(87.0, 28.0)
   * ];
   * var promise = Cesium.sampleTerrain(terrainProvider, 11, positions);
   * Cesium.when(promise, function(updatedPositions) {
   *     // positions[0].height and positions[1].height have been updated.
   *     // updatedPositions is just a reference to positions.
   * });
   */
  function sampleTerrain(terrainProvider, level, positions) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("terrainProvider", terrainProvider);
    Check.typeOf.number("level", level);
    Check.defined("positions", positions);
    //>>includeEnd('debug');

    return terrainProvider.readyPromise.then(function () {
      return doSampling(terrainProvider, level, positions);
    });
  }

  function doSampling(terrainProvider, level, positions) {
    var tilingScheme = terrainProvider.tilingScheme;

    var i;

    // Sort points into a set of tiles
    var tileRequests = []; // Result will be an Array as it's easier to work with
    var tileRequestSet = {}; // A unique set
    for (i = 0; i < positions.length; ++i) {
      var xy = tilingScheme.positionToTileXY(positions[i], level);
      var key = xy.toString();

      if (!tileRequestSet.hasOwnProperty(key)) {
        // When tile is requested for the first time
        var value = {
          x: xy.x,
          y: xy.y,
          level: level,
          tilingScheme: tilingScheme,
          terrainProvider: terrainProvider,
          positions: [],
        };
        tileRequestSet[key] = value;
        tileRequests.push(value);
      }

      // Now append to array of points for the tile
      tileRequestSet[key].positions.push(positions[i]);
    }

    // Send request for each required tile
    var tilePromises = [];
    for (i = 0; i < tileRequests.length; ++i) {
      var tileRequest = tileRequests[i];
      var requestPromise = tileRequest.terrainProvider.requestTileGeometry(
        tileRequest.x,
        tileRequest.y,
        tileRequest.level
      );
      var tilePromise = requestPromise
        .then(createInterpolateFunction(tileRequest))
        .otherwise(createMarkFailedFunction(tileRequest));
      tilePromises.push(tilePromise);
    }

    return when.all(tilePromises, function () {
      return positions;
    });
  }

  function createInterpolateFunction(tileRequest) {
    var tilePositions = tileRequest.positions;
    var rectangle = tileRequest.tilingScheme.tileXYToRectangle(
      tileRequest.x,
      tileRequest.y,
      tileRequest.level
    );
    return function (terrainData) {
      for (var i = 0; i < tilePositions.length; ++i) {
        var position = tilePositions[i];
        position.height = terrainData.interpolateHeight(
          rectangle,
          position.longitude,
          position.latitude
        );
      }
    };
  }

  function createMarkFailedFunction(tileRequest) {
    var tilePositions = tileRequest.positions;
    return function () {
      for (var i = 0; i < tilePositions.length; ++i) {
        var position = tilePositions[i];
        position.height = undefined;
      }
    };
  }

  var scratchCartesian2$7 = new Cartesian2();

  /**
   * Initiates a sampleTerrain() request at the maximum available tile level for a terrain dataset.
   *
   * @function sampleTerrainMostDetailed
   *
   * @param {TerrainProvider} terrainProvider The terrain provider from which to query heights.
   * @param {Cartographic[]} positions The positions to update with terrain heights.
   * @returns {Promise.<Cartographic[]>} A promise that resolves to the provided list of positions when terrain the query has completed.  This
   *                                     promise will reject if the terrain provider's `availability` property is undefined.
   *
   * @example
   * // Query the terrain height of two Cartographic positions
   * var terrainProvider = Cesium.createWorldTerrain();
   * var positions = [
   *     Cesium.Cartographic.fromDegrees(86.925145, 27.988257),
   *     Cesium.Cartographic.fromDegrees(87.0, 28.0)
   * ];
   * var promise = Cesium.sampleTerrainMostDetailed(terrainProvider, positions);
   * Cesium.when(promise, function(updatedPositions) {
   *     // positions[0].height and positions[1].height have been updated.
   *     // updatedPositions is just a reference to positions.
   * });
   */
  function sampleTerrainMostDetailed(terrainProvider, positions) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(terrainProvider)) {
      throw new DeveloperError("terrainProvider is required.");
    }
    if (!defined(positions)) {
      throw new DeveloperError("positions is required.");
    }
    //>>includeEnd('debug');

    return terrainProvider.readyPromise.then(function () {
      var byLevel = [];
      var maxLevels = [];

      var availability = terrainProvider.availability;

      //>>includeStart('debug', pragmas.debug);
      if (!defined(availability)) {
        throw new DeveloperError(
          "sampleTerrainMostDetailed requires a terrain provider that has tile availability."
        );
      }
      //>>includeEnd('debug');

      var promises = [];
      for (var i = 0; i < positions.length; ++i) {
        var position = positions[i];
        var maxLevel = availability.computeMaximumLevelAtPosition(position);
        maxLevels[i] = maxLevel;
        if (maxLevel === 0) {
          // This is a special case where we have a parent terrain and we are requesting
          // heights from an area that isn't covered by the top level terrain at all.
          // This will essentially trigger the loading of the parent terrains root tile
          terrainProvider.tilingScheme.positionToTileXY(
            position,
            1,
            scratchCartesian2$7
          );
          var promise = terrainProvider.loadTileDataAvailability(
            scratchCartesian2$7.x,
            scratchCartesian2$7.y,
            1
          );
          if (defined(promise)) {
            promises.push(promise);
          }
        }

        var atLevel = byLevel[maxLevel];
        if (!defined(atLevel)) {
          byLevel[maxLevel] = atLevel = [];
        }
        atLevel.push(position);
      }

      return when
        .all(promises)
        .then(function () {
          return when.all(
            byLevel.map(function (positionsAtLevel, index) {
              if (defined(positionsAtLevel)) {
                return sampleTerrain(terrainProvider, index, positionsAtLevel);
              }
            })
          );
        })
        .then(function () {
          var changedPositions = [];
          for (var i = 0; i < positions.length; ++i) {
            var position = positions[i];
            var maxLevel = availability.computeMaximumLevelAtPosition(position);

            if (maxLevel !== maxLevels[i]) {
              // Now that we loaded the max availability, a higher level has become available
              changedPositions.push(position);
            }
          }

          if (changedPositions.length > 0) {
            return sampleTerrainMostDetailed(terrainProvider, changedPositions);
          }
        })
        .then(function () {
          return positions;
        });
    });
  }

  /**
   * Subdivides an array into a number of smaller, equal sized arrays.
   *
   * @function subdivideArray
   *
   * @param {Array} array The array to divide.
   * @param {Number} numberOfArrays The number of arrays to divide the provided array into.
   *
   * @exception {DeveloperError} numberOfArrays must be greater than 0.
   */
  function subdivideArray(array, numberOfArrays) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(array)) {
      throw new DeveloperError("array is required.");
    }

    if (!defined(numberOfArrays) || numberOfArrays < 1) {
      throw new DeveloperError("numberOfArrays must be greater than 0.");
    }
    //>>includeEnd('debug');

    var result = [];
    var len = array.length;
    var i = 0;
    while (i < len) {
      var size = Math.ceil((len - i) / numberOfArrays--);
      result.push(array.slice(i, i + size));
      i += size;
    }
    return result;
  }

  function webGLConstantToGlslType(webGLValue) {
    switch (webGLValue) {
      case WebGLConstants$1.FLOAT:
        return "float";
      case WebGLConstants$1.FLOAT_VEC2:
        return "vec2";
      case WebGLConstants$1.FLOAT_VEC3:
        return "vec3";
      case WebGLConstants$1.FLOAT_VEC4:
        return "vec4";
      case WebGLConstants$1.FLOAT_MAT2:
        return "mat2";
      case WebGLConstants$1.FLOAT_MAT3:
        return "mat3";
      case WebGLConstants$1.FLOAT_MAT4:
        return "mat4";
      case WebGLConstants$1.SAMPLER_2D:
        return "sampler2D";
      case WebGLConstants$1.BOOL:
        return "bool";
    }
  }

  /**
   * Wraps a function on the provided objects with another function called in the
   * object's context so that the new function is always called immediately
   * before the old one.
   *
   * @private
   */
  function wrapFunction(obj, oldFunction, newFunction) {
    //>>includeStart('debug', pragmas.debug);
    if (typeof oldFunction !== "function") {
      throw new DeveloperError("oldFunction is required to be a function.");
    }

    if (typeof newFunction !== "function") {
      throw new DeveloperError("oldFunction is required to be a function.");
    }
    //>>includeEnd('debug');

    return function () {
      newFunction.apply(obj, arguments);
      oldFunction.apply(obj, arguments);
    };
  }

  /**
   * A {@link Property} whose value does not change with respect to simulation time.
   *
   * @alias ConstantProperty
   * @constructor
   *
   * @param {*} [value] The property value.
   *
   * @see ConstantPositionProperty
   */
  function ConstantProperty(value) {
    this._value = undefined;
    this._hasClone = false;
    this._hasEquals = false;
    this._definitionChanged = new Event();
    this.setValue(value);
  }

  Object.defineProperties(ConstantProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.
     * This property always returns <code>true</code>.
     * @memberof ConstantProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      value: true,
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value.
     * @memberof ConstantProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
  });

  /**
   * Gets the value of the property.
   *
   * @param {JulianDate} [time] The time for which to retrieve the value.  This parameter is unused since the value does not change with respect to time.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ConstantProperty.prototype.getValue = function (time, result) {
    return this._hasClone ? this._value.clone(result) : this._value;
  };

  /**
   * Sets the value of the property.
   *
   * @param {*} value The property value.
   */
  ConstantProperty.prototype.setValue = function (value) {
    var oldValue = this._value;
    if (oldValue !== value) {
      var isDefined = defined(value);
      var hasClone = isDefined && typeof value.clone === "function";
      var hasEquals = isDefined && typeof value.equals === "function";

      var changed = !hasEquals || !value.equals(oldValue);
      if (changed) {
        this._hasClone = hasClone;
        this._hasEquals = hasEquals;
        this._value = !hasClone ? value : value.clone(this._value);
        this._definitionChanged.raiseEvent(this);
      }
    }
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  ConstantProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof ConstantProperty && //
        ((!this._hasEquals && this._value === other._value) || //
          (this._hasEquals && this._value.equals(other._value))))
    );
  };

  /**
   * Gets this property's value.
   *
   * @returns {*} This property's value.
   */
  ConstantProperty.prototype.valueOf = function () {
    return this._value;
  };

  /**
   * Creates a string representing this property's value.
   *
   * @returns {String} A string representing the property's value.
   */
  ConstantProperty.prototype.toString = function () {
    return String(this._value);
  };

  function createProperty(
    name,
    privateName,
    subscriptionName,
    configurable,
    createPropertyCallback
  ) {
    return {
      configurable: configurable,
      get: function () {
        return this[privateName];
      },
      set: function (value) {
        var oldValue = this[privateName];
        var subscription = this[subscriptionName];
        if (defined(subscription)) {
          subscription();
          this[subscriptionName] = undefined;
        }

        var hasValue = value !== undefined;
        if (
          hasValue &&
          (!defined(value) || !defined(value.getValue)) &&
          defined(createPropertyCallback)
        ) {
          value = createPropertyCallback(value);
        }

        if (oldValue !== value) {
          this[privateName] = value;
          this._definitionChanged.raiseEvent(this, name, value, oldValue);
        }

        if (defined(value) && defined(value.definitionChanged)) {
          this[subscriptionName] = value.definitionChanged.addEventListener(
            function () {
              this._definitionChanged.raiseEvent(this, name, value, value);
            },
            this
          );
        }
      },
    };
  }

  function createConstantProperty(value) {
    return new ConstantProperty(value);
  }

  /**
   * Used to consistently define all DataSources graphics objects.
   * This is broken into two functions because the Chrome profiler does a better
   * job of optimizing lookups if it notices that the string is constant throughout the function.
   * @private
   */
  function createPropertyDescriptor(name, configurable, createPropertyCallback) {
    //Safari 8.0.3 has a JavaScript bug that causes it to confuse two variables and treat them as the same.
    //The two extra toString calls work around the issue.
    return createProperty(
      name,
      "_" + name.toString(),
      "_" + name.toString() + "Subscription",
      defaultValue(configurable, false),
      defaultValue(createPropertyCallback, createConstantProperty)
    );
  }

  /**
   * @typedef {Object} BillboardGraphics.ConstructorOptions
   *
   * Initialization options for the BillboardGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the billboard.
   * @property {Property | string | HTMLCanvasElement} [image] A Property specifying the Image, URI, or Canvas to use for the billboard.
   * @property {Property | number} [scale=1.0] A numeric Property specifying the scale to apply to the image size.
   * @property {Property | Cartesian2} [pixelOffset=Cartesian2.ZERO] A {@link Cartesian2} Property specifying the pixel offset.
   * @property {Property | Cartesian3} [eyeOffset=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the eye offset.
   * @property {Property | HorizontalOrigin} [horizontalOrigin=HorizontalOrigin.CENTER] A Property specifying the {@link HorizontalOrigin}.
   * @property {Property | VerticalOrigin} [verticalOrigin=VerticalOrigin.CENTER] A Property specifying the {@link VerticalOrigin}.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | Color} [color=Color.WHITE] A Property specifying the tint {@link Color} of the image.
   * @property {Property | number} [rotation=0] A numeric Property specifying the rotation about the alignedAxis.
   * @property {Property | Cartesian3} [alignedAxis=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the unit vector axis of rotation.
   * @property {Property | boolean} [sizeInMeters] A boolean Property specifying whether this billboard's size should be measured in meters.
   * @property {Property | number} [width] A numeric Property specifying the width of the billboard in pixels, overriding the native size.
   * @property {Property | number} [height] A numeric Property specifying the height of the billboard in pixels, overriding the native size.
   * @property {Property | NearFarScalar} [scaleByDistance] A {@link NearFarScalar} Property used to scale the point based on distance from the camera.
   * @property {Property | NearFarScalar} [translucencyByDistance] A {@link NearFarScalar} Property used to set translucency based on distance from the camera.
   * @property {Property | NearFarScalar} [pixelOffsetScaleByDistance] A {@link NearFarScalar} Property used to set pixelOffset based on distance from the camera.
   * @property {Property | BoundingRectangle} [imageSubRegion] A Property specifying a {@link BoundingRectangle} that defines a sub-region of the image to use for the billboard, rather than the entire image, measured in pixels from the bottom-left.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this billboard will be displayed.
   * @property {Property | number} [disableDepthTestDistance] A Property specifying the distance from the camera at which to disable the depth test to.
   */

  /**
   * Describes a two dimensional icon located at the position of the containing {@link Entity}.
   * <p>
   * <div align='center'>
   * <img src='Images/Billboard.png' width='400' height='300' /><br />
   * Example billboards
   * </div>
   * </p>
   *
   * @alias BillboardGraphics
   * @constructor
   *
   * @param {BillboardGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Billboards.html|Cesium Sandcastle Billboard Demo}
   */
  function BillboardGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._image = undefined;
    this._imageSubscription = undefined;
    this._scale = undefined;
    this._scaleSubscription = undefined;
    this._pixelOffset = undefined;
    this._pixelOffsetSubscription = undefined;
    this._eyeOffset = undefined;
    this._eyeOffsetSubscription = undefined;
    this._horizontalOrigin = undefined;
    this._horizontalOriginSubscription = undefined;
    this._verticalOrigin = undefined;
    this._verticalOriginSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._color = undefined;
    this._colorSubscription = undefined;
    this._rotation = undefined;
    this._rotationSubscription = undefined;
    this._alignedAxis = undefined;
    this._alignedAxisSubscription = undefined;
    this._sizeInMeters = undefined;
    this._sizeInMetersSubscription = undefined;
    this._width = undefined;
    this._widthSubscription = undefined;
    this._height = undefined;
    this._heightSubscription = undefined;
    this._scaleByDistance = undefined;
    this._scaleByDistanceSubscription = undefined;
    this._translucencyByDistance = undefined;
    this._translucencyByDistanceSubscription = undefined;
    this._pixelOffsetScaleByDistance = undefined;
    this._pixelOffsetScaleByDistanceSubscription = undefined;
    this._imageSubRegion = undefined;
    this._imageSubRegionSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._disableDepthTestDistance = undefined;
    this._disableDepthTestDistanceSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(BillboardGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof BillboardGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the billboard.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the Image, URI, or Canvas to use for the billboard.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    image: createPropertyDescriptor("image"),

    /**
     * Gets or sets the numeric Property specifying the uniform scale to apply to the image.
     * A scale greater than <code>1.0</code> enlarges the billboard while a scale less than <code>1.0</code> shrinks it.
     * <p>
     * <div align='center'>
     * <img src='Images/Billboard.setScale.png' width='400' height='300' /><br/>
     * From left to right in the above image, the scales are <code>0.5</code>, <code>1.0</code>, and <code>2.0</code>.
     * </div>
     * </p>
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    scale: createPropertyDescriptor("scale"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the billboard's pixel offset in screen space
     * from the origin of this billboard.  This is commonly used to align multiple billboards and labels at
     * the same position, e.g., an image and text.  The screen space origin is the top, left corner of the
     * canvas; <code>x</code> increases from left to right, and <code>y</code> increases from top to bottom.
     * <p>
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><code>default</code><br/><img src='Images/Billboard.setPixelOffset.default.png' width='250' height='188' /></td>
     * <td align='center'><code>b.pixeloffset = new Cartesian2(50, 25);</code><br/><img src='Images/Billboard.setPixelOffset.x50y-25.png' width='250' height='188' /></td>
     * </tr></table>
     * The billboard's origin is indicated by the yellow point.
     * </div>
     * </p>
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default Cartesian2.ZERO
     */
    pixelOffset: createPropertyDescriptor("pixelOffset"),

    /**
     * Gets or sets the {@link Cartesian3} Property specifying the billboard's offset in eye coordinates.
     * Eye coordinates is a left-handed coordinate system, where <code>x</code> points towards the viewer's
     * right, <code>y</code> points up, and <code>z</code> points into the screen.
     * <p>
     * An eye offset is commonly used to arrange multiple billboards or objects at the same position, e.g., to
     * arrange a billboard above its corresponding 3D model.
     * </p>
     * Below, the billboard is positioned at the center of the Earth but an eye offset makes it always
     * appear on top of the Earth regardless of the viewer's or Earth's orientation.
     * <p>
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.one.png' width='250' height='188' /></td>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.two.png' width='250' height='188' /></td>
     * </tr></table>
     * <code>b.eyeOffset = new Cartesian3(0.0, 8000000.0, 0.0);</code>
     * </div>
     * </p>
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default Cartesian3.ZERO
     */
    eyeOffset: createPropertyDescriptor("eyeOffset"),

    /**
     * Gets or sets the Property specifying the {@link HorizontalOrigin}.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default HorizontalOrigin.CENTER
     */
    horizontalOrigin: createPropertyDescriptor("horizontalOrigin"),

    /**
     * Gets or sets the Property specifying the {@link VerticalOrigin}.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default VerticalOrigin.CENTER
     */
    verticalOrigin: createPropertyDescriptor("verticalOrigin"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the Property specifying the {@link Color} that is multiplied with the <code>image</code>.
     * This has two common use cases.  First, the same white texture may be used by many different billboards,
     * each with a different color, to create colored billboards. Second, the color's alpha component can be
     * used to make the billboard translucent as shown below. An alpha of <code>0.0</code> makes the billboard
     * transparent, and <code>1.0</code> makes the billboard opaque.
     * <p>
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><code>default</code><br/><img src='Images/Billboard.setColor.Alpha255.png' width='250' height='188' /></td>
     * <td align='center'><code>alpha : 0.5</code><br/><img src='Images/Billboard.setColor.Alpha127.png' width='250' height='188' /></td>
     * </tr></table>
     * </div>
     * </p>
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the numeric Property specifying the rotation of the image
     * counter clockwise from the <code>alignedAxis</code>.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    rotation: createPropertyDescriptor("rotation"),

    /**
     * Gets or sets the {@link Cartesian3} Property specifying the unit vector axis of rotation
     * in the fixed frame. When set to Cartesian3.ZERO the rotation is from the top of the screen.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default Cartesian3.ZERO
     */
    alignedAxis: createPropertyDescriptor("alignedAxis"),

    /**
     * Gets or sets the boolean Property specifying if this billboard's size will be measured in meters.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    sizeInMeters: createPropertyDescriptor("sizeInMeters"),

    /**
     * Gets or sets the numeric Property specifying the width of the billboard in pixels.
     * When undefined, the native width is used.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    width: createPropertyDescriptor("width"),

    /**
     * Gets or sets the numeric Property specifying the height of the billboard in pixels.
     * When undefined, the native height is used.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    height: createPropertyDescriptor("height"),

    /**
     * Gets or sets {@link NearFarScalar} Property specifying the scale of the billboard based on the distance from the camera.
     * A billboard's scale will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the billboard's scale remains clamped to the nearest bound.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    scaleByDistance: createPropertyDescriptor("scaleByDistance"),

    /**
     * Gets or sets {@link NearFarScalar} Property specifying the translucency of the billboard based on the distance from the camera.
     * A billboard's translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the billboard's translucency remains clamped to the nearest bound.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    translucencyByDistance: createPropertyDescriptor("translucencyByDistance"),

    /**
     * Gets or sets {@link NearFarScalar} Property specifying the pixel offset of the billboard based on the distance from the camera.
     * A billboard's pixel offset will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the billboard's pixel offset remains clamped to the nearest bound.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    pixelOffsetScaleByDistance: createPropertyDescriptor(
      "pixelOffsetScaleByDistance"
    ),

    /**
     * Gets or sets the Property specifying a {@link BoundingRectangle} that defines a
     * sub-region of the <code>image</code> to use for the billboard, rather than the entire image,
     * measured in pixels from the bottom-left.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    imageSubRegion: createPropertyDescriptor("imageSubRegion"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this billboard will be displayed.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
     * When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.
     * @memberof BillboardGraphics.prototype
     * @type {Property|undefined}
     */
    disableDepthTestDistance: createPropertyDescriptor(
      "disableDepthTestDistance"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {BillboardGraphics} [result] The object onto which to store the result.
   * @returns {BillboardGraphics} The modified result parameter or a new instance if one was not provided.
   */
  BillboardGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new BillboardGraphics(this);
    }
    result.show = this._show;
    result.image = this._image;
    result.scale = this._scale;
    result.pixelOffset = this._pixelOffset;
    result.eyeOffset = this._eyeOffset;
    result.horizontalOrigin = this._horizontalOrigin;
    result.verticalOrigin = this._verticalOrigin;
    result.heightReference = this._heightReference;
    result.color = this._color;
    result.rotation = this._rotation;
    result.alignedAxis = this._alignedAxis;
    result.sizeInMeters = this._sizeInMeters;
    result.width = this._width;
    result.height = this._height;
    result.scaleByDistance = this._scaleByDistance;
    result.translucencyByDistance = this._translucencyByDistance;
    result.pixelOffsetScaleByDistance = this._pixelOffsetScaleByDistance;
    result.imageSubRegion = this._imageSubRegion;
    result.distanceDisplayCondition = this._distanceDisplayCondition;
    result.disableDepthTestDistance = this._disableDepthTestDistance;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {BillboardGraphics} source The object to be merged into this object.
   */
  BillboardGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this._show, source.show);
    this.image = defaultValue(this._image, source.image);
    this.scale = defaultValue(this._scale, source.scale);
    this.pixelOffset = defaultValue(this._pixelOffset, source.pixelOffset);
    this.eyeOffset = defaultValue(this._eyeOffset, source.eyeOffset);
    this.horizontalOrigin = defaultValue(
      this._horizontalOrigin,
      source.horizontalOrigin
    );
    this.verticalOrigin = defaultValue(
      this._verticalOrigin,
      source.verticalOrigin
    );
    this.heightReference = defaultValue(
      this._heightReference,
      source.heightReference
    );
    this.color = defaultValue(this._color, source.color);
    this.rotation = defaultValue(this._rotation, source.rotation);
    this.alignedAxis = defaultValue(this._alignedAxis, source.alignedAxis);
    this.sizeInMeters = defaultValue(this._sizeInMeters, source.sizeInMeters);
    this.width = defaultValue(this._width, source.width);
    this.height = defaultValue(this._height, source.height);
    this.scaleByDistance = defaultValue(
      this._scaleByDistance,
      source.scaleByDistance
    );
    this.translucencyByDistance = defaultValue(
      this._translucencyByDistance,
      source.translucencyByDistance
    );
    this.pixelOffsetScaleByDistance = defaultValue(
      this._pixelOffsetScaleByDistance,
      source.pixelOffsetScaleByDistance
    );
    this.imageSubRegion = defaultValue(
      this._imageSubRegion,
      source.imageSubRegion
    );
    this.distanceDisplayCondition = defaultValue(
      this._distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.disableDepthTestDistance = defaultValue(
      this._disableDepthTestDistance,
      source.disableDepthTestDistance
    );
  };

  /**
   * Represents the position relative to the terrain.
   *
   * @enum {Number}
   */
  var HeightReference = {
    /**
     * The position is absolute.
     * @type {Number}
     * @constant
     */
    NONE: 0,

    /**
     * The position is clamped to the terrain.
     * @type {Number}
     * @constant
     */
    CLAMP_TO_GROUND: 1,

    /**
     * The position height is the height above the terrain.
     * @type {Number}
     * @constant
     */
    RELATIVE_TO_GROUND: 2,
  };
  var HeightReference$1 = Object.freeze(HeightReference);

  /**
   * The horizontal location of an origin relative to an object, e.g., a {@link Billboard}
   * or {@link Label}.  For example, setting the horizontal origin to <code>LEFT</code>
   * or <code>RIGHT</code> will display a billboard to the left or right (in screen space)
   * of the anchor position.
   * <br /><br />
   * <div align='center'>
   * <img src='Images/Billboard.setHorizontalOrigin.png' width='648' height='196' /><br />
   * </div>
   *
   * @enum {Number}
   *
   * @see Billboard#horizontalOrigin
   * @see Label#horizontalOrigin
   */
  var HorizontalOrigin = {
    /**
     * The origin is at the horizontal center of the object.
     *
     * @type {Number}
     * @constant
     */
    CENTER: 0,

    /**
     * The origin is on the left side of the object.
     *
     * @type {Number}
     * @constant
     */
    LEFT: 1,

    /**
     * The origin is on the right side of the object.
     *
     * @type {Number}
     * @constant
     */
    RIGHT: -1,
  };
  var HorizontalOrigin$1 = Object.freeze(HorizontalOrigin);

  /**
   * The vertical location of an origin relative to an object, e.g., a {@link Billboard}
   * or {@link Label}.  For example, setting the vertical origin to <code>TOP</code>
   * or <code>BOTTOM</code> will display a billboard above or below (in screen space)
   * the anchor position.
   * <br /><br />
   * <div align='center'>
   * <img src='Images/Billboard.setVerticalOrigin.png' width='695' height='175' /><br />
   * </div>
   *
   * @enum {Number}
   *
   * @see Billboard#verticalOrigin
   * @see Label#verticalOrigin
   */
  var VerticalOrigin = {
    /**
     * The origin is at the vertical center between <code>BASELINE</code> and <code>TOP</code>.
     *
     * @type {Number}
     * @constant
     */
    CENTER: 0,

    /**
     * The origin is at the bottom of the object.
     *
     * @type {Number}
     * @constant
     */
    BOTTOM: 1,

    /**
     * If the object contains text, the origin is at the baseline of the text, else the origin is at the bottom of the object.
     *
     * @type {Number}
     * @constant
     */
    BASELINE: 2,

    /**
     * The origin is at the top of the object.
     *
     * @type {Number}
     * @constant
     */
    TOP: -1,
  };
  var VerticalOrigin$1 = Object.freeze(VerticalOrigin);

  /**
   * The state of a BoundingSphere computation being performed by a {@link Visualizer}.
   * @enum {Number}
   * @private
   */
  var BoundingSphereState = {
    /**
     * The BoundingSphere has been computed.
     * @type BoundingSphereState
     * @constant
     */
    DONE: 0,
    /**
     * The BoundingSphere is still being computed.
     * @type BoundingSphereState
     * @constant
     */
    PENDING: 1,
    /**
     * The BoundingSphere does not exist.
     * @type BoundingSphereState
     * @constant
     */
    FAILED: 2,
  };
  var BoundingSphereState$1 = Object.freeze(BoundingSphereState);

  /**
   * The interface for all properties, which represent a value that can optionally vary over time.
   * This type defines an interface and cannot be instantiated directly.
   *
   * @alias Property
   * @constructor
   * @abstract
   *
   * @see CompositeProperty
   * @see ConstantProperty
   * @see SampledProperty
   * @see TimeIntervalCollectionProperty
   * @see MaterialProperty
   * @see PositionProperty
   * @see ReferenceProperty
   */
  function Property() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(Property.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof Property.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof Property.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Gets the value of the property at the provided time.
   * @function
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  Property.prototype.getValue = DeveloperError.throwInstantiationError;

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   * @function
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  Property.prototype.equals = DeveloperError.throwInstantiationError;

  /**
   * @private
   */
  Property.equals = function (left, right) {
    return left === right || (defined(left) && left.equals(right));
  };

  /**
   * @private
   */
  Property.arrayEquals = function (left, right) {
    if (left === right) {
      return true;
    }
    if (!defined(left) || !defined(right) || left.length !== right.length) {
      return false;
    }
    var length = left.length;
    for (var i = 0; i < length; i++) {
      if (!Property.equals(left[i], right[i])) {
        return false;
      }
    }
    return true;
  };

  /**
   * @private
   */
  Property.isConstant = function (property) {
    return !defined(property) || property.isConstant;
  };

  /**
   * @private
   */
  Property.getValueOrUndefined = function (property, time, result) {
    return defined(property) ? property.getValue(time, result) : undefined;
  };

  /**
   * @private
   */
  Property.getValueOrDefault = function (property, time, valueDefault, result) {
    return defined(property)
      ? defaultValue(property.getValue(time, result), valueDefault)
      : valueDefault;
  };

  /**
   * @private
   */
  Property.getValueOrClonedDefault = function (
    property,
    time,
    valueDefault,
    result
  ) {
    var value;
    if (defined(property)) {
      value = property.getValue(time, result);
    }
    if (!defined(value)) {
      value = valueDefault.clone(value);
    }
    return value;
  };

  var defaultColor = Color.WHITE;
  var defaultEyeOffset = Cartesian3.ZERO;
  var defaultHeightReference = HeightReference$1.NONE;
  var defaultPixelOffset = Cartesian2.ZERO;
  var defaultScale$1 = 1.0;
  var defaultRotation$1 = 0.0;
  var defaultAlignedAxis = Cartesian3.ZERO;
  var defaultHorizontalOrigin = HorizontalOrigin$1.CENTER;
  var defaultVerticalOrigin = VerticalOrigin$1.CENTER;
  var defaultSizeInMeters = false;

  var positionScratch$4 = new Cartesian3();
  var colorScratch$1 = new Color();
  var eyeOffsetScratch = new Cartesian3();
  var pixelOffsetScratch = new Cartesian2();
  var scaleByDistanceScratch = new NearFarScalar();
  var translucencyByDistanceScratch = new NearFarScalar();
  var pixelOffsetScaleByDistanceScratch = new NearFarScalar();
  var boundingRectangleScratch = new BoundingRectangle();
  var distanceDisplayConditionScratch = new DistanceDisplayCondition();

  function EntityData(entity) {
    this.entity = entity;
    this.billboard = undefined;
    this.textureValue = undefined;
  }

  /**
   * A {@link Visualizer} which maps {@link Entity#billboard} to a {@link Billboard}.
   * @alias BillboardVisualizer
   * @constructor
   *
   * @param {EntityCluster} entityCluster The entity cluster to manage the collection of billboards and optionally cluster with other entities.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   */
  function BillboardVisualizer(entityCluster, entityCollection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entityCluster)) {
      throw new DeveloperError("entityCluster is required.");
    }
    if (!defined(entityCollection)) {
      throw new DeveloperError("entityCollection is required.");
    }
    //>>includeEnd('debug');

    entityCollection.collectionChanged.addEventListener(
      BillboardVisualizer.prototype._onCollectionChanged,
      this
    );

    this._cluster = entityCluster;
    this._entityCollection = entityCollection;
    this._items = new AssociativeArray();
    this._onCollectionChanged(entityCollection, entityCollection.values, [], []);
  }

  /**
   * Updates the primitives created by this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} This function always returns true.
   */
  BillboardVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var items = this._items.values;
    var cluster = this._cluster;

    for (var i = 0, len = items.length; i < len; i++) {
      var item = items[i];
      var entity = item.entity;
      var billboardGraphics = entity._billboard;
      var textureValue;
      var billboard = item.billboard;
      var show =
        entity.isShowing &&
        entity.isAvailable(time) &&
        Property.getValueOrDefault(billboardGraphics._show, time, true);
      var position;
      if (show) {
        position = Property.getValueOrUndefined(
          entity._position,
          time,
          positionScratch$4
        );
        textureValue = Property.getValueOrUndefined(
          billboardGraphics._image,
          time
        );
        show = defined(position) && defined(textureValue);
      }

      if (!show) {
        //don't bother creating or updating anything else
        returnPrimitive(item, entity, cluster);
        continue;
      }

      if (!Property.isConstant(entity._position)) {
        cluster._clusterDirty = true;
      }

      if (!defined(billboard)) {
        billboard = cluster.getBillboard(entity);
        billboard.id = entity;
        billboard.image = undefined;
        item.billboard = billboard;
      }

      billboard.show = show;
      if (!defined(billboard.image) || item.textureValue !== textureValue) {
        billboard.image = textureValue;
        item.textureValue = textureValue;
      }
      billboard.position = position;
      billboard.color = Property.getValueOrDefault(
        billboardGraphics._color,
        time,
        defaultColor,
        colorScratch$1
      );
      billboard.eyeOffset = Property.getValueOrDefault(
        billboardGraphics._eyeOffset,
        time,
        defaultEyeOffset,
        eyeOffsetScratch
      );
      billboard.heightReference = Property.getValueOrDefault(
        billboardGraphics._heightReference,
        time,
        defaultHeightReference
      );
      billboard.pixelOffset = Property.getValueOrDefault(
        billboardGraphics._pixelOffset,
        time,
        defaultPixelOffset,
        pixelOffsetScratch
      );
      billboard.scale = Property.getValueOrDefault(
        billboardGraphics._scale,
        time,
        defaultScale$1
      );
      billboard.rotation = Property.getValueOrDefault(
        billboardGraphics._rotation,
        time,
        defaultRotation$1
      );
      billboard.alignedAxis = Property.getValueOrDefault(
        billboardGraphics._alignedAxis,
        time,
        defaultAlignedAxis
      );
      billboard.horizontalOrigin = Property.getValueOrDefault(
        billboardGraphics._horizontalOrigin,
        time,
        defaultHorizontalOrigin
      );
      billboard.verticalOrigin = Property.getValueOrDefault(
        billboardGraphics._verticalOrigin,
        time,
        defaultVerticalOrigin
      );
      billboard.width = Property.getValueOrUndefined(
        billboardGraphics._width,
        time
      );
      billboard.height = Property.getValueOrUndefined(
        billboardGraphics._height,
        time
      );
      billboard.scaleByDistance = Property.getValueOrUndefined(
        billboardGraphics._scaleByDistance,
        time,
        scaleByDistanceScratch
      );
      billboard.translucencyByDistance = Property.getValueOrUndefined(
        billboardGraphics._translucencyByDistance,
        time,
        translucencyByDistanceScratch
      );
      billboard.pixelOffsetScaleByDistance = Property.getValueOrUndefined(
        billboardGraphics._pixelOffsetScaleByDistance,
        time,
        pixelOffsetScaleByDistanceScratch
      );
      billboard.sizeInMeters = Property.getValueOrDefault(
        billboardGraphics._sizeInMeters,
        time,
        defaultSizeInMeters
      );
      billboard.distanceDisplayCondition = Property.getValueOrUndefined(
        billboardGraphics._distanceDisplayCondition,
        time,
        distanceDisplayConditionScratch
      );
      billboard.disableDepthTestDistance = Property.getValueOrUndefined(
        billboardGraphics._disableDepthTestDistance,
        time
      );

      var subRegion = Property.getValueOrUndefined(
        billboardGraphics._imageSubRegion,
        time,
        boundingRectangleScratch
      );
      if (defined(subRegion)) {
        billboard.setImageSubRegion(billboard._imageId, subRegion);
      }
    }
    return true;
  };

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  BillboardVisualizer.prototype.getBoundingSphere = function (entity, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var item = this._items.get(entity.id);
    if (!defined(item) || !defined(item.billboard)) {
      return BoundingSphereState$1.FAILED;
    }

    var billboard = item.billboard;
    if (billboard.heightReference === HeightReference$1.NONE) {
      result.center = Cartesian3.clone(billboard.position, result.center);
    } else {
      if (!defined(billboard._clampedPosition)) {
        return BoundingSphereState$1.PENDING;
      }
      result.center = Cartesian3.clone(billboard._clampedPosition, result.center);
    }
    result.radius = 0;
    return BoundingSphereState$1.DONE;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  BillboardVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  BillboardVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      BillboardVisualizer.prototype._onCollectionChanged,
      this
    );
    var entities = this._entityCollection.values;
    for (var i = 0; i < entities.length; i++) {
      this._cluster.removeBillboard(entities[i]);
    }
    return destroyObject(this);
  };

  BillboardVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed,
    changed
  ) {
    var i;
    var entity;
    var items = this._items;
    var cluster = this._cluster;

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      if (defined(entity._billboard) && defined(entity._position)) {
        items.set(entity.id, new EntityData(entity));
      }
    }

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      if (defined(entity._billboard) && defined(entity._position)) {
        if (!items.contains(entity.id)) {
          items.set(entity.id, new EntityData(entity));
        }
      } else {
        returnPrimitive(items.get(entity.id), entity, cluster);
        items.remove(entity.id);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      returnPrimitive(items.get(entity.id), entity, cluster);
      items.remove(entity.id);
    }
  };

  function returnPrimitive(item, entity, cluster) {
    if (defined(item)) {
      item.billboard = undefined;
      cluster.removeBillboard(entity);
    }
  }

  //This file is automatically rebuilt by the Cesium build process.
  var AllMaterialAppearanceFS = "varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
varying vec3 v_tangentEC;\n\
varying vec3 v_bitangentEC;\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
vec3 positionToEyeEC = -v_positionEC;\n\
mat3 tangentToEyeMatrix = czm_tangentToEyeSpaceMatrix(v_normalEC, v_tangentEC, v_bitangentEC);\n\
vec3 normalEC = normalize(v_normalEC);\n\
#ifdef FACE_FORWARD\n\
normalEC = faceforward(normalEC, vec3(0.0, 0.0, 1.0), -normalEC);\n\
#endif\n\
czm_materialInput materialInput;\n\
materialInput.normalEC = normalEC;\n\
materialInput.tangentToEyeMatrix = tangentToEyeMatrix;\n\
materialInput.positionToEyeEC = positionToEyeEC;\n\
materialInput.st = v_st;\n\
czm_material material = czm_getMaterial(materialInput);\n\
#ifdef FLAT\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#else\n\
gl_FragColor = czm_phong(normalize(positionToEyeEC), material, czm_lightDirectionEC);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var AllMaterialAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 normal;\n\
attribute vec3 tangent;\n\
attribute vec3 bitangent;\n\
attribute vec2 st;\n\
attribute float batchId;\n\
varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
varying vec3 v_tangentEC;\n\
varying vec3 v_bitangentEC;\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
vec4 p = czm_computePosition();\n\
v_positionEC = (czm_modelViewRelativeToEye * p).xyz;\n\
v_normalEC = czm_normal * normal;\n\
v_tangentEC = czm_normal * tangent;\n\
v_bitangentEC = czm_normal * bitangent;\n\
v_st = st;\n\
gl_Position = czm_modelViewProjectionRelativeToEye * p;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BasicMaterialAppearanceFS = "varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
void main()\n\
{\n\
vec3 positionToEyeEC = -v_positionEC;\n\
vec3 normalEC = normalize(v_normalEC);\n\
#ifdef FACE_FORWARD\n\
normalEC = faceforward(normalEC, vec3(0.0, 0.0, 1.0), -normalEC);\n\
#endif\n\
czm_materialInput materialInput;\n\
materialInput.normalEC = normalEC;\n\
materialInput.positionToEyeEC = positionToEyeEC;\n\
czm_material material = czm_getMaterial(materialInput);\n\
#ifdef FLAT\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#else\n\
gl_FragColor = czm_phong(normalize(positionToEyeEC), material, czm_lightDirectionEC);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BasicMaterialAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 normal;\n\
attribute float batchId;\n\
varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
void main()\n\
{\n\
vec4 p = czm_computePosition();\n\
v_positionEC = (czm_modelViewRelativeToEye * p).xyz;\n\
v_normalEC = czm_normal * normal;\n\
gl_Position = czm_modelViewProjectionRelativeToEye * p;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var TexturedMaterialAppearanceFS = "varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
vec3 positionToEyeEC = -v_positionEC;\n\
vec3 normalEC = normalize(v_normalEC);\n\
#ifdef FACE_FORWARD\n\
normalEC = faceforward(normalEC, vec3(0.0, 0.0, 1.0), -normalEC);\n\
#endif\n\
czm_materialInput materialInput;\n\
materialInput.normalEC = normalEC;\n\
materialInput.positionToEyeEC = positionToEyeEC;\n\
materialInput.st = v_st;\n\
czm_material material = czm_getMaterial(materialInput);\n\
#ifdef FLAT\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#else\n\
gl_FragColor = czm_phong(normalize(positionToEyeEC), material, czm_lightDirectionEC);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var TexturedMaterialAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 normal;\n\
attribute vec2 st;\n\
attribute float batchId;\n\
varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
vec4 p = czm_computePosition();\n\
v_positionEC = (czm_modelViewRelativeToEye * p).xyz;\n\
v_normalEC = czm_normal * normal;\n\
v_st = st;\n\
gl_Position = czm_modelViewProjectionRelativeToEye * p;\n\
}\n\
";

  /**
   * Determines how two pixels' values are combined.
   *
   * @enum {Number}
   */
  var BlendEquation = {
    /**
     * Pixel values are added componentwise.  This is used in additive blending for translucency.
     *
     * @type {Number}
     * @constant
     */
    ADD: WebGLConstants$1.FUNC_ADD,

    /**
     * Pixel values are subtracted componentwise (source - destination).  This is used in alpha blending for translucency.
     *
     * @type {Number}
     * @constant
     */
    SUBTRACT: WebGLConstants$1.FUNC_SUBTRACT,

    /**
     * Pixel values are subtracted componentwise (destination - source).
     *
     * @type {Number}
     * @constant
     */
    REVERSE_SUBTRACT: WebGLConstants$1.FUNC_REVERSE_SUBTRACT,

    /**
     * Pixel values are given to the minimum function (min(source, destination)).
     *
     * This equation operates on each pixel color component.
     *
     * @type {Number}
     * @constant
     */
    MIN: WebGLConstants$1.MIN,

    /**
     * Pixel values are given to the maximum function (max(source, destination)).
     *
     * This equation operates on each pixel color component.
     *
     * @type {Number}
     * @constant
     */
    MAX: WebGLConstants$1.MAX,
  };
  var BlendEquation$1 = Object.freeze(BlendEquation);

  /**
   * Determines how blending factors are computed.
   *
   * @enum {Number}
   */
  var BlendFunction = {
    /**
     * The blend factor is zero.
     *
     * @type {Number}
     * @constant
     */
    ZERO: WebGLConstants$1.ZERO,

    /**
     * The blend factor is one.
     *
     * @type {Number}
     * @constant
     */
    ONE: WebGLConstants$1.ONE,

    /**
     * The blend factor is the source color.
     *
     * @type {Number}
     * @constant
     */
    SOURCE_COLOR: WebGLConstants$1.SRC_COLOR,

    /**
     * The blend factor is one minus the source color.
     *
     * @type {Number}
     * @constant
     */
    ONE_MINUS_SOURCE_COLOR: WebGLConstants$1.ONE_MINUS_SRC_COLOR,

    /**
     * The blend factor is the destination color.
     *
     * @type {Number}
     * @constant
     */
    DESTINATION_COLOR: WebGLConstants$1.DST_COLOR,

    /**
     * The blend factor is one minus the destination color.
     *
     * @type {Number}
     * @constant
     */
    ONE_MINUS_DESTINATION_COLOR: WebGLConstants$1.ONE_MINUS_DST_COLOR,

    /**
     * The blend factor is the source alpha.
     *
     * @type {Number}
     * @constant
     */
    SOURCE_ALPHA: WebGLConstants$1.SRC_ALPHA,

    /**
     * The blend factor is one minus the source alpha.
     *
     * @type {Number}
     * @constant
     */
    ONE_MINUS_SOURCE_ALPHA: WebGLConstants$1.ONE_MINUS_SRC_ALPHA,

    /**
     * The blend factor is the destination alpha.
     *
     * @type {Number}
     * @constant
     */
    DESTINATION_ALPHA: WebGLConstants$1.DST_ALPHA,

    /**
     * The blend factor is one minus the destination alpha.
     *
     * @type {Number}
     * @constant
     */
    ONE_MINUS_DESTINATION_ALPHA: WebGLConstants$1.ONE_MINUS_DST_ALPHA,

    /**
     * The blend factor is the constant color.
     *
     * @type {Number}
     * @constant
     */
    CONSTANT_COLOR: WebGLConstants$1.CONSTANT_COLOR,

    /**
     * The blend factor is one minus the constant color.
     *
     * @type {Number}
     * @constant
     */
    ONE_MINUS_CONSTANT_COLOR: WebGLConstants$1.ONE_MINUS_CONSTANT_COLOR,

    /**
     * The blend factor is the constant alpha.
     *
     * @type {Number}
     * @constant
     */
    CONSTANT_ALPHA: WebGLConstants$1.CONSTANT_ALPHA,

    /**
     * The blend factor is one minus the constant alpha.
     *
     * @type {Number}
     * @constant
     */
    ONE_MINUS_CONSTANT_ALPHA: WebGLConstants$1.ONE_MINUS_CONSTANT_ALPHA,

    /**
     * The blend factor is the saturated source alpha.
     *
     * @type {Number}
     * @constant
     */
    SOURCE_ALPHA_SATURATE: WebGLConstants$1.SRC_ALPHA_SATURATE,
  };
  var BlendFunction$1 = Object.freeze(BlendFunction);

  /**
   * The blending state combines {@link BlendEquation} and {@link BlendFunction} and the
   * <code>enabled</code> flag to define the full blending state for combining source and
   * destination fragments when rendering.
   * <p>
   * This is a helper when using custom render states with {@link Appearance#renderState}.
   * </p>
   *
   * @namespace
   */
  var BlendingState = {
    /**
     * Blending is disabled.
     *
     * @type {Object}
     * @constant
     */
    DISABLED: Object.freeze({
      enabled: false,
    }),

    /**
     * Blending is enabled using alpha blending, <code>source(source.alpha) + destination(1 - source.alpha)</code>.
     *
     * @type {Object}
     * @constant
     */
    ALPHA_BLEND: Object.freeze({
      enabled: true,
      equationRgb: BlendEquation$1.ADD,
      equationAlpha: BlendEquation$1.ADD,
      functionSourceRgb: BlendFunction$1.SOURCE_ALPHA,
      functionSourceAlpha: BlendFunction$1.ONE,
      functionDestinationRgb: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
      functionDestinationAlpha: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
    }),

    /**
     * Blending is enabled using alpha blending with premultiplied alpha, <code>source + destination(1 - source.alpha)</code>.
     *
     * @type {Object}
     * @constant
     */
    PRE_MULTIPLIED_ALPHA_BLEND: Object.freeze({
      enabled: true,
      equationRgb: BlendEquation$1.ADD,
      equationAlpha: BlendEquation$1.ADD,
      functionSourceRgb: BlendFunction$1.ONE,
      functionSourceAlpha: BlendFunction$1.ONE,
      functionDestinationRgb: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
      functionDestinationAlpha: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
    }),

    /**
     * Blending is enabled using additive blending, <code>source(source.alpha) + destination</code>.
     *
     * @type {Object}
     * @constant
     */
    ADDITIVE_BLEND: Object.freeze({
      enabled: true,
      equationRgb: BlendEquation$1.ADD,
      equationAlpha: BlendEquation$1.ADD,
      functionSourceRgb: BlendFunction$1.SOURCE_ALPHA,
      functionSourceAlpha: BlendFunction$1.ONE,
      functionDestinationRgb: BlendFunction$1.ONE,
      functionDestinationAlpha: BlendFunction$1.ONE,
    }),
  };
  var BlendingState$1 = Object.freeze(BlendingState);

  /**
   * Determines which triangles, if any, are culled.
   *
   * @enum {Number}
   */
  var CullFace = {
    /**
     * Front-facing triangles are culled.
     *
     * @type {Number}
     * @constant
     */
    FRONT: WebGLConstants$1.FRONT,

    /**
     * Back-facing triangles are culled.
     *
     * @type {Number}
     * @constant
     */
    BACK: WebGLConstants$1.BACK,

    /**
     * Both front-facing and back-facing triangles are culled.
     *
     * @type {Number}
     * @constant
     */
    FRONT_AND_BACK: WebGLConstants$1.FRONT_AND_BACK,
  };
  var CullFace$1 = Object.freeze(CullFace);

  /**
   * An appearance defines the full GLSL vertex and fragment shaders and the
   * render state used to draw a {@link Primitive}.  All appearances implement
   * this base <code>Appearance</code> interface.
   *
   * @alias Appearance
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.translucent=true] When <code>true</code>, the geometry is expected to appear translucent so {@link Appearance#renderState} has alpha blending enabled.
   * @param {Boolean} [options.closed=false] When <code>true</code>, the geometry is expected to be closed so {@link Appearance#renderState} has backface culling enabled.
   * @param {Material} [options.material=Material.ColorType] The material used to determine the fragment color.
   * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
   * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
   * @param {Object} [options.renderState] Optional render state to override the default render state.
   *
   * @see MaterialAppearance
   * @see EllipsoidSurfaceAppearance
   * @see PerInstanceColorAppearance
   * @see DebugAppearance
   * @see PolylineColorAppearance
   * @see PolylineMaterialAppearance
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Geometry%20and%20Appearances.html|Geometry and Appearances Demo}
   */
  function Appearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The material used to determine the fragment color.  Unlike other {@link Appearance}
     * properties, this is not read-only, so an appearance's material can change on the fly.
     *
     * @type Material
     *
     * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
     */
    this.material = options.material;

    /**
     * When <code>true</code>, the geometry is expected to appear translucent.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.translucent = defaultValue(options.translucent, true);

    this._vertexShaderSource = options.vertexShaderSource;
    this._fragmentShaderSource = options.fragmentShaderSource;
    this._renderState = options.renderState;
    this._closed = defaultValue(options.closed, false);
  }

  Object.defineProperties(Appearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof Appearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },

    /**
     * The GLSL source code for the fragment shader.  The full fragment shader
     * source is built procedurally taking into account the {@link Appearance#material}.
     * Use {@link Appearance#getFragmentShaderSource} to get the full source.
     *
     * @memberof Appearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     *
     * @memberof Appearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed.
     *
     * @memberof Appearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },
  });

  /**
   * Procedurally creates the full GLSL fragment shader source for this appearance
   * taking into account {@link Appearance#fragmentShaderSource} and {@link Appearance#material}.
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  Appearance.prototype.getFragmentShaderSource = function () {
    var parts = [];
    if (this.flat) {
      parts.push("#define FLAT");
    }
    if (this.faceForward) {
      parts.push("#define FACE_FORWARD");
    }
    if (defined(this.material)) {
      parts.push(this.material.shaderSource);
    }
    parts.push(this.fragmentShaderSource);

    return parts.join("\n");
  };

  /**
   * Determines if the geometry is translucent based on {@link Appearance#translucent} and {@link Material#isTranslucent}.
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  Appearance.prototype.isTranslucent = function () {
    return (
      (defined(this.material) && this.material.isTranslucent()) ||
      (!defined(this.material) && this.translucent)
    );
  };

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @returns {Object} The render state.
   */
  Appearance.prototype.getRenderState = function () {
    var translucent = this.isTranslucent();
    var rs = clone(this.renderState, false);
    if (translucent) {
      rs.depthMask = false;
      rs.blending = BlendingState$1.ALPHA_BLEND;
    } else {
      rs.depthMask = true;
    }
    return rs;
  };

  /**
   * @private
   */
  Appearance.getDefaultRenderState = function (translucent, closed, existing) {
    var rs = {
      depthTest: {
        enabled: true,
      },
    };

    if (translucent) {
      rs.depthMask = false;
      rs.blending = BlendingState$1.ALPHA_BLEND;
    }

    if (closed) {
      rs.cull = {
        enabled: true,
        face: CullFace$1.BACK,
      };
    }

    if (defined(existing)) {
      rs = combine(existing, rs, true);
    }

    return rs;
  };

  /**
   * @private
   */
  var ContextLimits = {
    _maximumCombinedTextureImageUnits: 0,
    _maximumCubeMapSize: 0,
    _maximumFragmentUniformVectors: 0,
    _maximumTextureImageUnits: 0,
    _maximumRenderbufferSize: 0,
    _maximumTextureSize: 0,
    _maximumVaryingVectors: 0,
    _maximumVertexAttributes: 0,
    _maximumVertexTextureImageUnits: 0,
    _maximumVertexUniformVectors: 0,
    _minimumAliasedLineWidth: 0,
    _maximumAliasedLineWidth: 0,
    _minimumAliasedPointSize: 0,
    _maximumAliasedPointSize: 0,
    _maximumViewportWidth: 0,
    _maximumViewportHeight: 0,
    _maximumTextureFilterAnisotropy: 0,
    _maximumDrawBuffers: 0,
    _maximumColorAttachments: 0,
    _highpFloatSupported: false,
    _highpIntSupported: false,
  };

  Object.defineProperties(ContextLimits, {
    /**
     * The maximum number of texture units that can be used from the vertex and fragment
     * shader with this WebGL implementation.  The minimum is eight.  If both shaders access the
     * same texture unit, this counts as two texture units.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_COMBINED_TEXTURE_IMAGE_UNITS</code>.
     */
    maximumCombinedTextureImageUnits: {
      get: function () {
        return ContextLimits._maximumCombinedTextureImageUnits;
      },
    },

    /**
     * The approximate maximum cube mape width and height supported by this WebGL implementation.
     * The minimum is 16, but most desktop and laptop implementations will support much larger sizes like 8,192.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_CUBE_MAP_TEXTURE_SIZE</code>.
     */
    maximumCubeMapSize: {
      get: function () {
        return ContextLimits._maximumCubeMapSize;
      },
    },

    /**
     * The maximum number of <code>vec4</code>, <code>ivec4</code>, and <code>bvec4</code>
     * uniforms that can be used by a fragment shader with this WebGL implementation.  The minimum is 16.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_FRAGMENT_UNIFORM_VECTORS</code>.
     */
    maximumFragmentUniformVectors: {
      get: function () {
        return ContextLimits._maximumFragmentUniformVectors;
      },
    },

    /**
     * The maximum number of texture units that can be used from the fragment shader with this WebGL implementation.  The minimum is eight.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_TEXTURE_IMAGE_UNITS</code>.
     */
    maximumTextureImageUnits: {
      get: function () {
        return ContextLimits._maximumTextureImageUnits;
      },
    },

    /**
     * The maximum renderbuffer width and height supported by this WebGL implementation.
     * The minimum is 16, but most desktop and laptop implementations will support much larger sizes like 8,192.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_RENDERBUFFER_SIZE</code>.
     */
    maximumRenderbufferSize: {
      get: function () {
        return ContextLimits._maximumRenderbufferSize;
      },
    },

    /**
     * The approximate maximum texture width and height supported by this WebGL implementation.
     * The minimum is 64, but most desktop and laptop implementations will support much larger sizes like 8,192.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_TEXTURE_SIZE</code>.
     */
    maximumTextureSize: {
      get: function () {
        return ContextLimits._maximumTextureSize;
      },
    },

    /**
     * The maximum number of <code>vec4</code> varying variables supported by this WebGL implementation.
     * The minimum is eight.  Matrices and arrays count as multiple <code>vec4</code>s.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_VARYING_VECTORS</code>.
     */
    maximumVaryingVectors: {
      get: function () {
        return ContextLimits._maximumVaryingVectors;
      },
    },

    /**
     * The maximum number of <code>vec4</code> vertex attributes supported by this WebGL implementation.  The minimum is eight.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_VERTEX_ATTRIBS</code>.
     */
    maximumVertexAttributes: {
      get: function () {
        return ContextLimits._maximumVertexAttributes;
      },
    },

    /**
     * The maximum number of texture units that can be used from the vertex shader with this WebGL implementation.
     * The minimum is zero, which means the GL does not support vertex texture fetch.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_VERTEX_TEXTURE_IMAGE_UNITS</code>.
     */
    maximumVertexTextureImageUnits: {
      get: function () {
        return ContextLimits._maximumVertexTextureImageUnits;
      },
    },

    /**
     * The maximum number of <code>vec4</code>, <code>ivec4</code>, and <code>bvec4</code>
     * uniforms that can be used by a vertex shader with this WebGL implementation.  The minimum is 16.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_VERTEX_UNIFORM_VECTORS</code>.
     */
    maximumVertexUniformVectors: {
      get: function () {
        return ContextLimits._maximumVertexUniformVectors;
      },
    },

    /**
     * The minimum aliased line width, in pixels, supported by this WebGL implementation.  It will be at most one.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>ALIASED_LINE_WIDTH_RANGE</code>.
     */
    minimumAliasedLineWidth: {
      get: function () {
        return ContextLimits._minimumAliasedLineWidth;
      },
    },

    /**
     * The maximum aliased line width, in pixels, supported by this WebGL implementation.  It will be at least one.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>ALIASED_LINE_WIDTH_RANGE</code>.
     */
    maximumAliasedLineWidth: {
      get: function () {
        return ContextLimits._maximumAliasedLineWidth;
      },
    },

    /**
     * The minimum aliased point size, in pixels, supported by this WebGL implementation.  It will be at most one.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>ALIASED_POINT_SIZE_RANGE</code>.
     */
    minimumAliasedPointSize: {
      get: function () {
        return ContextLimits._minimumAliasedPointSize;
      },
    },

    /**
     * The maximum aliased point size, in pixels, supported by this WebGL implementation.  It will be at least one.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>ALIASED_POINT_SIZE_RANGE</code>.
     */
    maximumAliasedPointSize: {
      get: function () {
        return ContextLimits._maximumAliasedPointSize;
      },
    },

    /**
     * The maximum supported width of the viewport.  It will be at least as large as the visible width of the associated canvas.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_VIEWPORT_DIMS</code>.
     */
    maximumViewportWidth: {
      get: function () {
        return ContextLimits._maximumViewportWidth;
      },
    },

    /**
     * The maximum supported height of the viewport.  It will be at least as large as the visible height of the associated canvas.
     * @memberof ContextLimits
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>MAX_VIEWPORT_DIMS</code>.
     */
    maximumViewportHeight: {
      get: function () {
        return ContextLimits._maximumViewportHeight;
      },
    },

    /**
     * The maximum degree of anisotropy for texture filtering
     * @memberof ContextLimits
     * @type {Number}
     */
    maximumTextureFilterAnisotropy: {
      get: function () {
        return ContextLimits._maximumTextureFilterAnisotropy;
      },
    },

    /**
     * The maximum number of simultaneous outputs that may be written in a fragment shader.
     * @memberof ContextLimits
     * @type {Number}
     */
    maximumDrawBuffers: {
      get: function () {
        return ContextLimits._maximumDrawBuffers;
      },
    },

    /**
     * The maximum number of color attachments supported.
     * @memberof ContextLimits
     * @type {Number}
     */
    maximumColorAttachments: {
      get: function () {
        return ContextLimits._maximumColorAttachments;
      },
    },

    /**
     * High precision float supported (<code>highp</code>) in fragment shaders.
     * @memberof ContextLimits
     * @type {Boolean}
     */
    highpFloatSupported: {
      get: function () {
        return ContextLimits._highpFloatSupported;
      },
    },

    /**
     * High precision int supported (<code>highp</code>) in fragment shaders.
     * @memberof ContextLimits
     * @type {Boolean}
     */
    highpIntSupported: {
      get: function () {
        return ContextLimits._highpIntSupported;
      },
    },
  });

  /**
   * @private
   */
  function CubeMapFace(
    context,
    texture,
    textureTarget,
    targetFace,
    internalFormat,
    pixelFormat,
    pixelDatatype,
    size,
    preMultiplyAlpha,
    flipY,
    initialized
  ) {
    this._context = context;
    this._texture = texture;
    this._textureTarget = textureTarget;
    this._targetFace = targetFace;
    this._pixelDatatype = pixelDatatype;
    this._internalFormat = internalFormat;
    this._pixelFormat = pixelFormat;
    this._size = size;
    this._preMultiplyAlpha = preMultiplyAlpha;
    this._flipY = flipY;
    this._initialized = initialized;
  }

  Object.defineProperties(CubeMapFace.prototype, {
    pixelFormat: {
      get: function () {
        return this._pixelFormat;
      },
    },
    pixelDatatype: {
      get: function () {
        return this._pixelDatatype;
      },
    },
    _target: {
      get: function () {
        return this._targetFace;
      },
    },
  });

  /**
   * Copies texels from the source to the cubemap's face.
   *
   * @param {Object} source The source ImageData, HTMLImageElement, HTMLCanvasElement, HTMLVideoElement, or an object with a width, height, and typed array as shown in the example.
   * @param {Number} [xOffset=0] An offset in the x direction in the cubemap where copying begins.
   * @param {Number} [yOffset=0] An offset in the y direction in the cubemap where copying begins.
   *
   * @exception {DeveloperError} xOffset must be greater than or equal to zero.
   * @exception {DeveloperError} yOffset must be greater than or equal to zero.
   * @exception {DeveloperError} xOffset + source.width must be less than or equal to width.
   * @exception {DeveloperError} yOffset + source.height must be less than or equal to height.
   * @exception {DeveloperError} This CubeMap was destroyed, i.e., destroy() was called.
   *
   * @example
   * // Create a cubemap with 1x1 faces, and make the +x face red.
   * var cubeMap = new CubeMap({
   *   context : context
   *   width : 1,
   *   height : 1
   * });
   * cubeMap.positiveX.copyFrom({
   *   width : 1,
   *   height : 1,
   *   arrayBufferView : new Uint8Array([255, 0, 0, 255])
   * });
   */
  CubeMapFace.prototype.copyFrom = function (source, xOffset, yOffset) {
    xOffset = defaultValue(xOffset, 0);
    yOffset = defaultValue(yOffset, 0);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("source", source);
    Check.typeOf.number.greaterThanOrEquals("xOffset", xOffset, 0);
    Check.typeOf.number.greaterThanOrEquals("yOffset", yOffset, 0);
    if (xOffset + source.width > this._size) {
      throw new DeveloperError(
        "xOffset + source.width must be less than or equal to width."
      );
    }
    if (yOffset + source.height > this._size) {
      throw new DeveloperError(
        "yOffset + source.height must be less than or equal to height."
      );
    }
    //>>includeEnd('debug');

    var gl = this._context._gl;
    var target = this._textureTarget;
    var targetFace = this._targetFace;

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(target, this._texture);

    var width = source.width;
    var height = source.height;
    var arrayBufferView = source.arrayBufferView;

    var size = this._size;
    var pixelFormat = this._pixelFormat;
    var internalFormat = this._internalFormat;
    var pixelDatatype = this._pixelDatatype;

    var preMultiplyAlpha = this._preMultiplyAlpha;
    var flipY = this._flipY;

    var unpackAlignment = 4;
    if (defined(arrayBufferView)) {
      unpackAlignment = PixelFormat$1.alignmentInBytes(
        pixelFormat,
        pixelDatatype,
        width
      );
    }

    gl.pixelStorei(gl.UNPACK_ALIGNMENT, unpackAlignment);

    var uploaded = false;
    if (!this._initialized) {
      if (xOffset === 0 && yOffset === 0 && width === size && height === size) {
        // initialize the entire texture
        if (defined(arrayBufferView)) {
          gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
          gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

          if (flipY) {
            arrayBufferView = PixelFormat$1.flipY(
              arrayBufferView,
              pixelFormat,
              pixelDatatype,
              size,
              size
            );
          }
          gl.texImage2D(
            targetFace,
            0,
            internalFormat,
            size,
            size,
            0,
            pixelFormat,
            PixelDatatype$1.toWebGLConstant(pixelDatatype, this._context),
            arrayBufferView
          );
        } else {
          // Only valid for DOM-Element uploads
          gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, preMultiplyAlpha);
          gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

          gl.texImage2D(
            targetFace,
            0,
            internalFormat,
            pixelFormat,
            PixelDatatype$1.toWebGLConstant(pixelDatatype, this._context),
            source
          );
        }
        uploaded = true;
      } else {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        // initialize the entire texture to zero
        var bufferView = PixelFormat$1.createTypedArray(
          pixelFormat,
          pixelDatatype,
          size,
          size
        );
        gl.texImage2D(
          targetFace,
          0,
          internalFormat,
          size,
          size,
          0,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, this._context),
          bufferView
        );
      }
      this._initialized = true;
    }

    if (!uploaded) {
      if (defined(arrayBufferView)) {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        if (flipY) {
          arrayBufferView = PixelFormat$1.flipY(
            arrayBufferView,
            pixelFormat,
            pixelDatatype,
            width,
            height
          );
        }
        gl.texSubImage2D(
          targetFace,
          0,
          xOffset,
          yOffset,
          width,
          height,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, this._context),
          arrayBufferView
        );
      } else {
        // Only valid for DOM-Element uploads
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, preMultiplyAlpha);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

        // Source: ImageData, HTMLImageElement, HTMLCanvasElement, or HTMLVideoElement
        gl.texSubImage2D(
          targetFace,
          0,
          xOffset,
          yOffset,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, this._context),
          source
        );
      }
    }

    gl.bindTexture(target, null);
  };

  /**
   * Copies texels from the framebuffer to the cubemap's face.
   *
   * @param {Number} [xOffset=0] An offset in the x direction in the cubemap where copying begins.
   * @param {Number} [yOffset=0] An offset in the y direction in the cubemap where copying begins.
   * @param {Number} [framebufferXOffset=0] An offset in the x direction in the framebuffer where copying begins from.
   * @param {Number} [framebufferYOffset=0] An offset in the y direction in the framebuffer where copying begins from.
   * @param {Number} [width=CubeMap's width] The width of the subimage to copy.
   * @param {Number} [height=CubeMap's height] The height of the subimage to copy.
   *
   * @exception {DeveloperError} Cannot call copyFromFramebuffer when the texture pixel data type is FLOAT.
   * @exception {DeveloperError} Cannot call copyFromFramebuffer when the texture pixel data type is HALF_FLOAT.
   * @exception {DeveloperError} This CubeMap was destroyed, i.e., destroy() was called.
   * @exception {DeveloperError} xOffset must be greater than or equal to zero.
   * @exception {DeveloperError} yOffset must be greater than or equal to zero.
   * @exception {DeveloperError} framebufferXOffset must be greater than or equal to zero.
   * @exception {DeveloperError} framebufferYOffset must be greater than or equal to zero.
   * @exception {DeveloperError} xOffset + source.width must be less than or equal to width.
   * @exception {DeveloperError} yOffset + source.height must be less than or equal to height.
   * @exception {DeveloperError} This CubeMap was destroyed, i.e., destroy() was called.
   *
   * @example
   * // Copy the framebuffer contents to the +x cube map face.
   * cubeMap.positiveX.copyFromFramebuffer();
   */
  CubeMapFace.prototype.copyFromFramebuffer = function (
    xOffset,
    yOffset,
    framebufferXOffset,
    framebufferYOffset,
    width,
    height
  ) {
    xOffset = defaultValue(xOffset, 0);
    yOffset = defaultValue(yOffset, 0);
    framebufferXOffset = defaultValue(framebufferXOffset, 0);
    framebufferYOffset = defaultValue(framebufferYOffset, 0);
    width = defaultValue(width, this._size);
    height = defaultValue(height, this._size);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("xOffset", xOffset, 0);
    Check.typeOf.number.greaterThanOrEquals("yOffset", yOffset, 0);
    Check.typeOf.number.greaterThanOrEquals(
      "framebufferXOffset",
      framebufferXOffset,
      0
    );
    Check.typeOf.number.greaterThanOrEquals(
      "framebufferYOffset",
      framebufferYOffset,
      0
    );
    if (xOffset + width > this._size) {
      throw new DeveloperError(
        "xOffset + source.width must be less than or equal to width."
      );
    }
    if (yOffset + height > this._size) {
      throw new DeveloperError(
        "yOffset + source.height must be less than or equal to height."
      );
    }
    if (this._pixelDatatype === PixelDatatype$1.FLOAT) {
      throw new DeveloperError(
        "Cannot call copyFromFramebuffer when the texture pixel data type is FLOAT."
      );
    }
    if (this._pixelDatatype === PixelDatatype$1.HALF_FLOAT) {
      throw new DeveloperError(
        "Cannot call copyFromFramebuffer when the texture pixel data type is HALF_FLOAT."
      );
    }
    //>>includeEnd('debug');

    var gl = this._context._gl;
    var target = this._textureTarget;

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(target, this._texture);
    gl.copyTexSubImage2D(
      this._targetFace,
      0,
      xOffset,
      yOffset,
      framebufferXOffset,
      framebufferYOffset,
      width,
      height
    );
    gl.bindTexture(target, null);
    this._initialized = true;
  };

  /**
   * @private
   */
  var MipmapHint = {
    DONT_CARE: WebGLConstants$1.DONT_CARE,
    FASTEST: WebGLConstants$1.FASTEST,
    NICEST: WebGLConstants$1.NICEST,

    validate: function (mipmapHint) {
      return (
        mipmapHint === MipmapHint.DONT_CARE ||
        mipmapHint === MipmapHint.FASTEST ||
        mipmapHint === MipmapHint.NICEST
      );
    },
  };
  var MipmapHint$1 = Object.freeze(MipmapHint);

  /**
   * Enumerates all possible filters used when magnifying WebGL textures.
   *
   * @enum {Number}
   *
   * @see TextureMinificationFilter
   */
  var TextureMagnificationFilter = {
    /**
     * Samples the texture by returning the closest pixel.
     *
     * @type {Number}
     * @constant
     */
    NEAREST: WebGLConstants$1.NEAREST,
    /**
     * Samples the texture through bi-linear interpolation of the four nearest pixels. This produces smoother results than <code>NEAREST</code> filtering.
     *
     * @type {Number}
     * @constant
     */
    LINEAR: WebGLConstants$1.LINEAR,
  };

  /**
   * Validates the given <code>textureMinificationFilter</code> with respect to the possible enum values.
   * @param textureMagnificationFilter
   * @returns {Boolean} <code>true</code> if <code>textureMagnificationFilter</code> is valid.
   *
   * @private
   */
  TextureMagnificationFilter.validate = function (textureMagnificationFilter) {
    return (
      textureMagnificationFilter === TextureMagnificationFilter.NEAREST ||
      textureMagnificationFilter === TextureMagnificationFilter.LINEAR
    );
  };

  var TextureMagnificationFilter$1 = Object.freeze(TextureMagnificationFilter);

  /**
   * Enumerates all possible filters used when minifying WebGL textures.
   *
   * @enum {Number}
   *
   * @see TextureMagnificationFilter
   */
  var TextureMinificationFilter = {
    /**
     * Samples the texture by returning the closest pixel.
     *
     * @type {Number}
     * @constant
     */
    NEAREST: WebGLConstants$1.NEAREST,
    /**
     * Samples the texture through bi-linear interpolation of the four nearest pixels. This produces smoother results than <code>NEAREST</code> filtering.
     *
     * @type {Number}
     * @constant
     */
    LINEAR: WebGLConstants$1.LINEAR,
    /**
     * Selects the nearest mip level and applies nearest sampling within that level.
     * <p>
     * Requires that the texture has a mipmap. The mip level is chosen by the view angle and screen-space size of the texture.
     * </p>
     *
     * @type {Number}
     * @constant
     */
    NEAREST_MIPMAP_NEAREST: WebGLConstants$1.NEAREST_MIPMAP_NEAREST,
    /**
     * Selects the nearest mip level and applies linear sampling within that level.
     * <p>
     * Requires that the texture has a mipmap. The mip level is chosen by the view angle and screen-space size of the texture.
     * </p>
     *
     * @type {Number}
     * @constant
     */
    LINEAR_MIPMAP_NEAREST: WebGLConstants$1.LINEAR_MIPMAP_NEAREST,
    /**
     * Read texture values with nearest sampling from two adjacent mip levels and linearly interpolate the results.
     * <p>
     * This option provides a good balance of visual quality and speed when sampling from a mipmapped texture.
     * </p>
     * <p>
     * Requires that the texture has a mipmap. The mip level is chosen by the view angle and screen-space size of the texture.
     * </p>
     *
     * @type {Number}
     * @constant
     */
    NEAREST_MIPMAP_LINEAR: WebGLConstants$1.NEAREST_MIPMAP_LINEAR,
    /**
     * Read texture values with linear sampling from two adjacent mip levels and linearly interpolate the results.
     * <p>
     * This option provides a good balance of visual quality and speed when sampling from a mipmapped texture.
     * </p>
     * <p>
     * Requires that the texture has a mipmap. The mip level is chosen by the view angle and screen-space size of the texture.
     * </p>
     * @type {Number}
     * @constant
     */
    LINEAR_MIPMAP_LINEAR: WebGLConstants$1.LINEAR_MIPMAP_LINEAR,
  };

  /**
   * Validates the given <code>textureMinificationFilter</code> with respect to the possible enum values.
   *
   * @private
   *
   * @param textureMinificationFilter
   * @returns {Boolean} <code>true</code> if <code>textureMinificationFilter</code> is valid.
   */
  TextureMinificationFilter.validate = function (textureMinificationFilter) {
    return (
      textureMinificationFilter === TextureMinificationFilter.NEAREST ||
      textureMinificationFilter === TextureMinificationFilter.LINEAR ||
      textureMinificationFilter ===
        TextureMinificationFilter.NEAREST_MIPMAP_NEAREST ||
      textureMinificationFilter ===
        TextureMinificationFilter.LINEAR_MIPMAP_NEAREST ||
      textureMinificationFilter ===
        TextureMinificationFilter.NEAREST_MIPMAP_LINEAR ||
      textureMinificationFilter === TextureMinificationFilter.LINEAR_MIPMAP_LINEAR
    );
  };

  var TextureMinificationFilter$1 = Object.freeze(TextureMinificationFilter);

  /**
   * @private
   */
  var TextureWrap = {
    CLAMP_TO_EDGE: WebGLConstants$1.CLAMP_TO_EDGE,
    REPEAT: WebGLConstants$1.REPEAT,
    MIRRORED_REPEAT: WebGLConstants$1.MIRRORED_REPEAT,

    validate: function (textureWrap) {
      return (
        textureWrap === TextureWrap.CLAMP_TO_EDGE ||
        textureWrap === TextureWrap.REPEAT ||
        textureWrap === TextureWrap.MIRRORED_REPEAT
      );
    },
  };
  var TextureWrap$1 = Object.freeze(TextureWrap);

  /**
   * @private
   */
  function Sampler(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var wrapS = defaultValue(options.wrapS, TextureWrap$1.CLAMP_TO_EDGE);
    var wrapT = defaultValue(options.wrapT, TextureWrap$1.CLAMP_TO_EDGE);
    var minificationFilter = defaultValue(
      options.minificationFilter,
      TextureMinificationFilter$1.LINEAR
    );
    var magnificationFilter = defaultValue(
      options.magnificationFilter,
      TextureMagnificationFilter$1.LINEAR
    );
    var maximumAnisotropy = defined(options.maximumAnisotropy)
      ? options.maximumAnisotropy
      : 1.0;

    //>>includeStart('debug', pragmas.debug);
    if (!TextureWrap$1.validate(wrapS)) {
      throw new DeveloperError("Invalid sampler.wrapS.");
    }

    if (!TextureWrap$1.validate(wrapT)) {
      throw new DeveloperError("Invalid sampler.wrapT.");
    }

    if (!TextureMinificationFilter$1.validate(minificationFilter)) {
      throw new DeveloperError("Invalid sampler.minificationFilter.");
    }

    if (!TextureMagnificationFilter$1.validate(magnificationFilter)) {
      throw new DeveloperError("Invalid sampler.magnificationFilter.");
    }

    Check.typeOf.number.greaterThanOrEquals(
      "maximumAnisotropy",
      maximumAnisotropy,
      1.0
    );
    //>>includeEnd('debug');

    this._wrapS = wrapS;
    this._wrapT = wrapT;
    this._minificationFilter = minificationFilter;
    this._magnificationFilter = magnificationFilter;
    this._maximumAnisotropy = maximumAnisotropy;
  }

  Object.defineProperties(Sampler.prototype, {
    wrapS: {
      get: function () {
        return this._wrapS;
      },
    },
    wrapT: {
      get: function () {
        return this._wrapT;
      },
    },
    minificationFilter: {
      get: function () {
        return this._minificationFilter;
      },
    },
    magnificationFilter: {
      get: function () {
        return this._magnificationFilter;
      },
    },
    maximumAnisotropy: {
      get: function () {
        return this._maximumAnisotropy;
      },
    },
  });

  Sampler.equals = function (left, right) {
    return (
      left === right ||
      (defined(left) &&
        defined(right) &&
        left._wrapS === right._wrapS &&
        left._wrapT === right._wrapT &&
        left._minificationFilter === right._minificationFilter &&
        left._magnificationFilter === right._magnificationFilter &&
        left._maximumAnisotropy === right._maximumAnisotropy)
    );
  };

  Sampler.NEAREST = Object.freeze(
    new Sampler({
      wrapS: TextureWrap$1.CLAMP_TO_EDGE,
      wrapT: TextureWrap$1.CLAMP_TO_EDGE,
      minificationFilter: TextureMinificationFilter$1.NEAREST,
      magnificationFilter: TextureMagnificationFilter$1.NEAREST,
    })
  );

  /**
   * @private
   */
  function CubeMap(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    var context = options.context;
    var source = options.source;
    var width;
    var height;

    if (defined(source)) {
      var faces = [
        source.positiveX,
        source.negativeX,
        source.positiveY,
        source.negativeY,
        source.positiveZ,
        source.negativeZ,
      ];

      //>>includeStart('debug', pragmas.debug);
      if (
        !faces[0] ||
        !faces[1] ||
        !faces[2] ||
        !faces[3] ||
        !faces[4] ||
        !faces[5]
      ) {
        throw new DeveloperError(
          "options.source requires positiveX, negativeX, positiveY, negativeY, positiveZ, and negativeZ faces."
        );
      }
      //>>includeEnd('debug');

      width = faces[0].width;
      height = faces[0].height;

      //>>includeStart('debug', pragmas.debug);
      for (var i = 1; i < 6; ++i) {
        if (
          Number(faces[i].width) !== width ||
          Number(faces[i].height) !== height
        ) {
          throw new DeveloperError(
            "Each face in options.source must have the same width and height."
          );
        }
      }
      //>>includeEnd('debug');
    } else {
      width = options.width;
      height = options.height;
    }

    var size = width;
    var pixelDatatype = defaultValue(
      options.pixelDatatype,
      PixelDatatype$1.UNSIGNED_BYTE
    );
    var pixelFormat = defaultValue(options.pixelFormat, PixelFormat$1.RGBA);
    var internalFormat = PixelFormat$1.toInternalFormat(
      pixelFormat,
      pixelDatatype,
      context
    );

    //>>includeStart('debug', pragmas.debug);
    if (!defined(width) || !defined(height)) {
      throw new DeveloperError(
        "options requires a source field to create an initialized cube map or width and height fields to create a blank cube map."
      );
    }

    if (width !== height) {
      throw new DeveloperError("Width must equal height.");
    }

    if (size <= 0) {
      throw new DeveloperError("Width and height must be greater than zero.");
    }

    if (size > ContextLimits.maximumCubeMapSize) {
      throw new DeveloperError(
        "Width and height must be less than or equal to the maximum cube map size (" +
          ContextLimits.maximumCubeMapSize +
          ").  Check maximumCubeMapSize."
      );
    }

    if (!PixelFormat$1.validate(pixelFormat)) {
      throw new DeveloperError("Invalid options.pixelFormat.");
    }

    if (PixelFormat$1.isDepthFormat(pixelFormat)) {
      throw new DeveloperError(
        "options.pixelFormat cannot be DEPTH_COMPONENT or DEPTH_STENCIL."
      );
    }

    if (!PixelDatatype$1.validate(pixelDatatype)) {
      throw new DeveloperError("Invalid options.pixelDatatype.");
    }

    if (pixelDatatype === PixelDatatype$1.FLOAT && !context.floatingPointTexture) {
      throw new DeveloperError(
        "When options.pixelDatatype is FLOAT, this WebGL implementation must support the OES_texture_float extension."
      );
    }

    if (
      pixelDatatype === PixelDatatype$1.HALF_FLOAT &&
      !context.halfFloatingPointTexture
    ) {
      throw new DeveloperError(
        "When options.pixelDatatype is HALF_FLOAT, this WebGL implementation must support the OES_texture_half_float extension."
      );
    }
    //>>includeEnd('debug');

    var sizeInBytes =
      PixelFormat$1.textureSizeInBytes(pixelFormat, pixelDatatype, size, size) * 6;

    // Use premultiplied alpha for opaque textures should perform better on Chrome:
    // http://media.tojicode.com/webglCamp4/#20
    var preMultiplyAlpha =
      options.preMultiplyAlpha ||
      pixelFormat === PixelFormat$1.RGB ||
      pixelFormat === PixelFormat$1.LUMINANCE;
    var flipY = defaultValue(options.flipY, true);

    var gl = context._gl;
    var textureTarget = gl.TEXTURE_CUBE_MAP;
    var texture = gl.createTexture();

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(textureTarget, texture);

    function createFace(target, sourceFace, preMultiplyAlpha, flipY) {
      var arrayBufferView = sourceFace.arrayBufferView;
      if (!defined(arrayBufferView)) {
        arrayBufferView = sourceFace.bufferView;
      }

      var unpackAlignment = 4;
      if (defined(arrayBufferView)) {
        unpackAlignment = PixelFormat$1.alignmentInBytes(
          pixelFormat,
          pixelDatatype,
          width
        );
      }

      gl.pixelStorei(gl.UNPACK_ALIGNMENT, unpackAlignment);

      if (defined(arrayBufferView)) {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        if (flipY) {
          arrayBufferView = PixelFormat$1.flipY(
            arrayBufferView,
            pixelFormat,
            pixelDatatype,
            size,
            size
          );
        }
        gl.texImage2D(
          target,
          0,
          internalFormat,
          size,
          size,
          0,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
          arrayBufferView
        );
      } else {
        // Only valid for DOM-Element uploads
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, preMultiplyAlpha);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

        // Source: ImageData, HTMLImageElement, HTMLCanvasElement, or HTMLVideoElement
        gl.texImage2D(
          target,
          0,
          internalFormat,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
          sourceFace
        );
      }
    }

    if (defined(source)) {
      createFace(
        gl.TEXTURE_CUBE_MAP_POSITIVE_X,
        source.positiveX,
        preMultiplyAlpha,
        flipY
      );
      createFace(
        gl.TEXTURE_CUBE_MAP_NEGATIVE_X,
        source.negativeX,
        preMultiplyAlpha,
        flipY
      );
      createFace(
        gl.TEXTURE_CUBE_MAP_POSITIVE_Y,
        source.positiveY,
        preMultiplyAlpha,
        flipY
      );
      createFace(
        gl.TEXTURE_CUBE_MAP_NEGATIVE_Y,
        source.negativeY,
        preMultiplyAlpha,
        flipY
      );
      createFace(
        gl.TEXTURE_CUBE_MAP_POSITIVE_Z,
        source.positiveZ,
        preMultiplyAlpha,
        flipY
      );
      createFace(
        gl.TEXTURE_CUBE_MAP_NEGATIVE_Z,
        source.negativeZ,
        preMultiplyAlpha,
        flipY
      );
    } else {
      gl.texImage2D(
        gl.TEXTURE_CUBE_MAP_POSITIVE_X,
        0,
        internalFormat,
        size,
        size,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
      gl.texImage2D(
        gl.TEXTURE_CUBE_MAP_NEGATIVE_X,
        0,
        internalFormat,
        size,
        size,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
      gl.texImage2D(
        gl.TEXTURE_CUBE_MAP_POSITIVE_Y,
        0,
        internalFormat,
        size,
        size,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
      gl.texImage2D(
        gl.TEXTURE_CUBE_MAP_NEGATIVE_Y,
        0,
        internalFormat,
        size,
        size,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
      gl.texImage2D(
        gl.TEXTURE_CUBE_MAP_POSITIVE_Z,
        0,
        internalFormat,
        size,
        size,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
      gl.texImage2D(
        gl.TEXTURE_CUBE_MAP_NEGATIVE_Z,
        0,
        internalFormat,
        size,
        size,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
    }
    gl.bindTexture(textureTarget, null);

    this._context = context;
    this._textureFilterAnisotropic = context._textureFilterAnisotropic;
    this._textureTarget = textureTarget;
    this._texture = texture;
    this._pixelFormat = pixelFormat;
    this._pixelDatatype = pixelDatatype;
    this._size = size;
    this._hasMipmap = false;
    this._sizeInBytes = sizeInBytes;
    this._preMultiplyAlpha = preMultiplyAlpha;
    this._flipY = flipY;
    this._sampler = undefined;

    var initialized = defined(source);
    this._positiveX = new CubeMapFace(
      context,
      texture,
      textureTarget,
      gl.TEXTURE_CUBE_MAP_POSITIVE_X,
      internalFormat,
      pixelFormat,
      pixelDatatype,
      size,
      preMultiplyAlpha,
      flipY,
      initialized
    );
    this._negativeX = new CubeMapFace(
      context,
      texture,
      textureTarget,
      gl.TEXTURE_CUBE_MAP_NEGATIVE_X,
      internalFormat,
      pixelFormat,
      pixelDatatype,
      size,
      preMultiplyAlpha,
      flipY,
      initialized
    );
    this._positiveY = new CubeMapFace(
      context,
      texture,
      textureTarget,
      gl.TEXTURE_CUBE_MAP_POSITIVE_Y,
      internalFormat,
      pixelFormat,
      pixelDatatype,
      size,
      preMultiplyAlpha,
      flipY,
      initialized
    );
    this._negativeY = new CubeMapFace(
      context,
      texture,
      textureTarget,
      gl.TEXTURE_CUBE_MAP_NEGATIVE_Y,
      internalFormat,
      pixelFormat,
      pixelDatatype,
      size,
      preMultiplyAlpha,
      flipY,
      initialized
    );
    this._positiveZ = new CubeMapFace(
      context,
      texture,
      textureTarget,
      gl.TEXTURE_CUBE_MAP_POSITIVE_Z,
      internalFormat,
      pixelFormat,
      pixelDatatype,
      size,
      preMultiplyAlpha,
      flipY,
      initialized
    );
    this._negativeZ = new CubeMapFace(
      context,
      texture,
      textureTarget,
      gl.TEXTURE_CUBE_MAP_NEGATIVE_Z,
      internalFormat,
      pixelFormat,
      pixelDatatype,
      size,
      preMultiplyAlpha,
      flipY,
      initialized
    );

    this.sampler = defined(options.sampler) ? options.sampler : new Sampler();
  }

  Object.defineProperties(CubeMap.prototype, {
    positiveX: {
      get: function () {
        return this._positiveX;
      },
    },
    negativeX: {
      get: function () {
        return this._negativeX;
      },
    },
    positiveY: {
      get: function () {
        return this._positiveY;
      },
    },
    negativeY: {
      get: function () {
        return this._negativeY;
      },
    },
    positiveZ: {
      get: function () {
        return this._positiveZ;
      },
    },
    negativeZ: {
      get: function () {
        return this._negativeZ;
      },
    },
    sampler: {
      get: function () {
        return this._sampler;
      },
      set: function (sampler) {
        var minificationFilter = sampler.minificationFilter;
        var magnificationFilter = sampler.magnificationFilter;

        var mipmap =
          minificationFilter ===
            TextureMinificationFilter$1.NEAREST_MIPMAP_NEAREST ||
          minificationFilter ===
            TextureMinificationFilter$1.NEAREST_MIPMAP_LINEAR ||
          minificationFilter ===
            TextureMinificationFilter$1.LINEAR_MIPMAP_NEAREST ||
          minificationFilter === TextureMinificationFilter$1.LINEAR_MIPMAP_LINEAR;

        var context = this._context;
        var pixelDatatype = this._pixelDatatype;

        // float textures only support nearest filtering unless the linear extensions are supported, so override the sampler's settings
        if (
          (pixelDatatype === PixelDatatype$1.FLOAT &&
            !context.textureFloatLinear) ||
          (pixelDatatype === PixelDatatype$1.HALF_FLOAT &&
            !context.textureHalfFloatLinear)
        ) {
          minificationFilter = mipmap
            ? TextureMinificationFilter$1.NEAREST_MIPMAP_NEAREST
            : TextureMinificationFilter$1.NEAREST;
          magnificationFilter = TextureMagnificationFilter$1.NEAREST;
        }

        var gl = context._gl;
        var target = this._textureTarget;

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(target, this._texture);
        gl.texParameteri(target, gl.TEXTURE_MIN_FILTER, minificationFilter);
        gl.texParameteri(target, gl.TEXTURE_MAG_FILTER, magnificationFilter);
        gl.texParameteri(target, gl.TEXTURE_WRAP_S, sampler.wrapS);
        gl.texParameteri(target, gl.TEXTURE_WRAP_T, sampler.wrapT);
        if (defined(this._textureFilterAnisotropic)) {
          gl.texParameteri(
            target,
            this._textureFilterAnisotropic.TEXTURE_MAX_ANISOTROPY_EXT,
            sampler.maximumAnisotropy
          );
        }
        gl.bindTexture(target, null);

        this._sampler = sampler;
      },
    },
    pixelFormat: {
      get: function () {
        return this._pixelFormat;
      },
    },
    pixelDatatype: {
      get: function () {
        return this._pixelDatatype;
      },
    },
    width: {
      get: function () {
        return this._size;
      },
    },
    height: {
      get: function () {
        return this._size;
      },
    },
    sizeInBytes: {
      get: function () {
        if (this._hasMipmap) {
          return Math.floor((this._sizeInBytes * 4) / 3);
        }
        return this._sizeInBytes;
      },
    },
    preMultiplyAlpha: {
      get: function () {
        return this._preMultiplyAlpha;
      },
    },
    flipY: {
      get: function () {
        return this._flipY;
      },
    },

    _target: {
      get: function () {
        return this._textureTarget;
      },
    },
  });

  /**
   * Generates a complete mipmap chain for each cubemap face.
   *
   * @param {MipmapHint} [hint=MipmapHint.DONT_CARE] A performance vs. quality hint.
   *
   * @exception {DeveloperError} hint is invalid.
   * @exception {DeveloperError} This CubeMap's width must be a power of two to call generateMipmap().
   * @exception {DeveloperError} This CubeMap's height must be a power of two to call generateMipmap().
   * @exception {DeveloperError} This CubeMap was destroyed, i.e., destroy() was called.
   *
   * @example
   * // Generate mipmaps, and then set the sampler so mipmaps are used for
   * // minification when the cube map is sampled.
   * cubeMap.generateMipmap();
   * cubeMap.sampler = new Sampler({
   *   minificationFilter : Cesium.TextureMinificationFilter.NEAREST_MIPMAP_LINEAR
   * });
   */
  CubeMap.prototype.generateMipmap = function (hint) {
    hint = defaultValue(hint, MipmapHint$1.DONT_CARE);

    //>>includeStart('debug', pragmas.debug);
    if (this._size > 1 && !CesiumMath.isPowerOfTwo(this._size)) {
      throw new DeveloperError(
        "width and height must be a power of two to call generateMipmap()."
      );
    }
    if (!MipmapHint$1.validate(hint)) {
      throw new DeveloperError("hint is invalid.");
    }
    //>>includeEnd('debug');

    this._hasMipmap = true;

    var gl = this._context._gl;
    var target = this._textureTarget;
    gl.hint(gl.GENERATE_MIPMAP_HINT, hint);
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(target, this._texture);
    gl.generateMipmap(target);
    gl.bindTexture(target, null);
  };

  CubeMap.prototype.isDestroyed = function () {
    return false;
  };

  CubeMap.prototype.destroy = function () {
    this._context._gl.deleteTexture(this._texture);
    this._positiveX = destroyObject(this._positiveX);
    this._negativeX = destroyObject(this._negativeX);
    this._positiveY = destroyObject(this._positiveY);
    this._negativeY = destroyObject(this._negativeY);
    this._positiveZ = destroyObject(this._positiveZ);
    this._negativeZ = destroyObject(this._negativeZ);
    return destroyObject(this);
  };

  /**
   * @private
   */
  function Texture(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    var context = options.context;
    var width = options.width;
    var height = options.height;
    var source = options.source;

    if (defined(source)) {
      if (!defined(width)) {
        width = defaultValue(source.videoWidth, source.width);
      }
      if (!defined(height)) {
        height = defaultValue(source.videoHeight, source.height);
      }
    }

    var pixelFormat = defaultValue(options.pixelFormat, PixelFormat$1.RGBA);
    var pixelDatatype = defaultValue(
      options.pixelDatatype,
      PixelDatatype$1.UNSIGNED_BYTE
    );
    var internalFormat = PixelFormat$1.toInternalFormat(
      pixelFormat,
      pixelDatatype,
      context
    );

    var isCompressed = PixelFormat$1.isCompressedFormat(internalFormat);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(width) || !defined(height)) {
      throw new DeveloperError(
        "options requires a source field to create an initialized texture or width and height fields to create a blank texture."
      );
    }

    Check.typeOf.number.greaterThan("width", width, 0);

    if (width > ContextLimits.maximumTextureSize) {
      throw new DeveloperError(
        "Width must be less than or equal to the maximum texture size (" +
          ContextLimits.maximumTextureSize +
          ").  Check maximumTextureSize."
      );
    }

    Check.typeOf.number.greaterThan("height", height, 0);

    if (height > ContextLimits.maximumTextureSize) {
      throw new DeveloperError(
        "Height must be less than or equal to the maximum texture size (" +
          ContextLimits.maximumTextureSize +
          ").  Check maximumTextureSize."
      );
    }

    if (!PixelFormat$1.validate(pixelFormat)) {
      throw new DeveloperError("Invalid options.pixelFormat.");
    }

    if (!isCompressed && !PixelDatatype$1.validate(pixelDatatype)) {
      throw new DeveloperError("Invalid options.pixelDatatype.");
    }

    if (
      pixelFormat === PixelFormat$1.DEPTH_COMPONENT &&
      pixelDatatype !== PixelDatatype$1.UNSIGNED_SHORT &&
      pixelDatatype !== PixelDatatype$1.UNSIGNED_INT
    ) {
      throw new DeveloperError(
        "When options.pixelFormat is DEPTH_COMPONENT, options.pixelDatatype must be UNSIGNED_SHORT or UNSIGNED_INT."
      );
    }

    if (
      pixelFormat === PixelFormat$1.DEPTH_STENCIL &&
      pixelDatatype !== PixelDatatype$1.UNSIGNED_INT_24_8
    ) {
      throw new DeveloperError(
        "When options.pixelFormat is DEPTH_STENCIL, options.pixelDatatype must be UNSIGNED_INT_24_8."
      );
    }

    if (pixelDatatype === PixelDatatype$1.FLOAT && !context.floatingPointTexture) {
      throw new DeveloperError(
        "When options.pixelDatatype is FLOAT, this WebGL implementation must support the OES_texture_float extension.  Check context.floatingPointTexture."
      );
    }

    if (
      pixelDatatype === PixelDatatype$1.HALF_FLOAT &&
      !context.halfFloatingPointTexture
    ) {
      throw new DeveloperError(
        "When options.pixelDatatype is HALF_FLOAT, this WebGL implementation must support the OES_texture_half_float extension. Check context.halfFloatingPointTexture."
      );
    }

    if (PixelFormat$1.isDepthFormat(pixelFormat)) {
      if (defined(source)) {
        throw new DeveloperError(
          "When options.pixelFormat is DEPTH_COMPONENT or DEPTH_STENCIL, source cannot be provided."
        );
      }

      if (!context.depthTexture) {
        throw new DeveloperError(
          "When options.pixelFormat is DEPTH_COMPONENT or DEPTH_STENCIL, this WebGL implementation must support WEBGL_depth_texture.  Check context.depthTexture."
        );
      }
    }

    if (isCompressed) {
      if (!defined(source) || !defined(source.arrayBufferView)) {
        throw new DeveloperError(
          "When options.pixelFormat is compressed, options.source.arrayBufferView must be defined."
        );
      }

      if (PixelFormat$1.isDXTFormat(internalFormat) && !context.s3tc) {
        throw new DeveloperError(
          "When options.pixelFormat is S3TC compressed, this WebGL implementation must support the WEBGL_texture_compression_s3tc extension. Check context.s3tc."
        );
      } else if (PixelFormat$1.isPVRTCFormat(internalFormat) && !context.pvrtc) {
        throw new DeveloperError(
          "When options.pixelFormat is PVRTC compressed, this WebGL implementation must support the WEBGL_texture_compression_pvrtc extension. Check context.pvrtc."
        );
      } else if (PixelFormat$1.isETC1Format(internalFormat) && !context.etc1) {
        throw new DeveloperError(
          "When options.pixelFormat is ETC1 compressed, this WebGL implementation must support the WEBGL_texture_compression_etc1 extension. Check context.etc1."
        );
      }

      if (
        PixelFormat$1.compressedTextureSizeInBytes(
          internalFormat,
          width,
          height
        ) !== source.arrayBufferView.byteLength
      ) {
        throw new DeveloperError(
          "The byte length of the array buffer is invalid for the compressed texture with the given width and height."
        );
      }
    }
    //>>includeEnd('debug');

    // Use premultiplied alpha for opaque textures should perform better on Chrome:
    // http://media.tojicode.com/webglCamp4/#20
    var preMultiplyAlpha =
      options.preMultiplyAlpha ||
      pixelFormat === PixelFormat$1.RGB ||
      pixelFormat === PixelFormat$1.LUMINANCE;
    var flipY = defaultValue(options.flipY, true);

    var initialized = true;

    var gl = context._gl;
    var textureTarget = gl.TEXTURE_2D;
    var texture = gl.createTexture();

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(textureTarget, texture);

    var unpackAlignment = 4;
    if (defined(source) && defined(source.arrayBufferView) && !isCompressed) {
      unpackAlignment = PixelFormat$1.alignmentInBytes(
        pixelFormat,
        pixelDatatype,
        width
      );
    }

    gl.pixelStorei(gl.UNPACK_ALIGNMENT, unpackAlignment);

    if (defined(source)) {
      if (defined(source.arrayBufferView)) {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        // Source: typed array
        var arrayBufferView = source.arrayBufferView;
        if (isCompressed) {
          gl.compressedTexImage2D(
            textureTarget,
            0,
            internalFormat,
            width,
            height,
            0,
            arrayBufferView
          );
        } else {
          if (flipY) {
            arrayBufferView = PixelFormat$1.flipY(
              arrayBufferView,
              pixelFormat,
              pixelDatatype,
              width,
              height
            );
          }
          gl.texImage2D(
            textureTarget,
            0,
            internalFormat,
            width,
            height,
            0,
            pixelFormat,
            PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
            arrayBufferView
          );

          if (defined(source.mipLevels)) {
            var mipWidth = width;
            var mipHeight = height;
            for (var i = 0; i < source.mipLevels.length; ++i) {
              mipWidth = Math.floor(mipWidth / 2) | 0;
              if (mipWidth < 1) {
                mipWidth = 1;
              }
              mipHeight = Math.floor(mipHeight / 2) | 0;
              if (mipHeight < 1) {
                mipHeight = 1;
              }
              gl.texImage2D(
                textureTarget,
                i + 1,
                internalFormat,
                mipWidth,
                mipHeight,
                0,
                pixelFormat,
                PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
                source.mipLevels[i]
              );
            }
          }
        }
      } else if (defined(source.framebuffer)) {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        // Source: framebuffer
        if (source.framebuffer !== context.defaultFramebuffer) {
          source.framebuffer._bind();
        }

        gl.copyTexImage2D(
          textureTarget,
          0,
          internalFormat,
          source.xOffset,
          source.yOffset,
          width,
          height,
          0
        );

        if (source.framebuffer !== context.defaultFramebuffer) {
          source.framebuffer._unBind();
        }
      } else {
        // Only valid for DOM-Element uploads
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, preMultiplyAlpha);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

        // Source: ImageData, HTMLImageElement, HTMLCanvasElement, or HTMLVideoElement
        gl.texImage2D(
          textureTarget,
          0,
          internalFormat,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
          source
        );
      }
    } else {
      gl.texImage2D(
        textureTarget,
        0,
        internalFormat,
        width,
        height,
        0,
        pixelFormat,
        PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
        null
      );
      initialized = false;
    }
    gl.bindTexture(textureTarget, null);

    var sizeInBytes;
    if (isCompressed) {
      sizeInBytes = PixelFormat$1.compressedTextureSizeInBytes(
        pixelFormat,
        width,
        height
      );
    } else {
      sizeInBytes = PixelFormat$1.textureSizeInBytes(
        pixelFormat,
        pixelDatatype,
        width,
        height
      );
    }

    this._id = createGuid();
    this._context = context;
    this._textureFilterAnisotropic = context._textureFilterAnisotropic;
    this._textureTarget = textureTarget;
    this._texture = texture;
    this._internalFormat = internalFormat;
    this._pixelFormat = pixelFormat;
    this._pixelDatatype = pixelDatatype;
    this._width = width;
    this._height = height;
    this._dimensions = new Cartesian2(width, height);
    this._hasMipmap = false;
    this._sizeInBytes = sizeInBytes;
    this._preMultiplyAlpha = preMultiplyAlpha;
    this._flipY = flipY;
    this._initialized = initialized;
    this._sampler = undefined;

    this.sampler = defined(options.sampler) ? options.sampler : new Sampler();
  }

  /**
   * This function is identical to using the Texture constructor except that it can be
   * replaced with a mock/spy in tests.
   * @private
   */
  Texture.create = function (options) {
    return new Texture(options);
  };

  /**
   * Creates a texture, and copies a subimage of the framebuffer to it.  When called without arguments,
   * the texture is the same width and height as the framebuffer and contains its contents.
   *
   * @param {Object} options Object with the following properties:
   * @param {Context} options.context The context in which the Texture gets created.
   * @param {PixelFormat} [options.pixelFormat=PixelFormat.RGB] The texture's internal pixel format.
   * @param {Number} [options.framebufferXOffset=0] An offset in the x direction in the framebuffer where copying begins from.
   * @param {Number} [options.framebufferYOffset=0] An offset in the y direction in the framebuffer where copying begins from.
   * @param {Number} [options.width=canvas.clientWidth] The width of the texture in texels.
   * @param {Number} [options.height=canvas.clientHeight] The height of the texture in texels.
   * @param {Framebuffer} [options.framebuffer=defaultFramebuffer] The framebuffer from which to create the texture.  If this
   *        parameter is not specified, the default framebuffer is used.
   * @returns {Texture} A texture with contents from the framebuffer.
   *
   * @exception {DeveloperError} Invalid pixelFormat.
   * @exception {DeveloperError} pixelFormat cannot be DEPTH_COMPONENT, DEPTH_STENCIL or a compressed format.
   * @exception {DeveloperError} framebufferXOffset must be greater than or equal to zero.
   * @exception {DeveloperError} framebufferYOffset must be greater than or equal to zero.
   * @exception {DeveloperError} framebufferXOffset + width must be less than or equal to canvas.clientWidth.
   * @exception {DeveloperError} framebufferYOffset + height must be less than or equal to canvas.clientHeight.
   *
   *
   * @example
   * // Create a texture with the contents of the framebuffer.
   * var t = Texture.fromFramebuffer({
   *     context : context
   * });
   *
   * @see Sampler
   *
   * @private
   */
  Texture.fromFramebuffer = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    var context = options.context;
    var gl = context._gl;

    var pixelFormat = defaultValue(options.pixelFormat, PixelFormat$1.RGB);
    var framebufferXOffset = defaultValue(options.framebufferXOffset, 0);
    var framebufferYOffset = defaultValue(options.framebufferYOffset, 0);
    var width = defaultValue(options.width, gl.drawingBufferWidth);
    var height = defaultValue(options.height, gl.drawingBufferHeight);
    var framebuffer = options.framebuffer;

    //>>includeStart('debug', pragmas.debug);
    if (!PixelFormat$1.validate(pixelFormat)) {
      throw new DeveloperError("Invalid pixelFormat.");
    }
    if (
      PixelFormat$1.isDepthFormat(pixelFormat) ||
      PixelFormat$1.isCompressedFormat(pixelFormat)
    ) {
      throw new DeveloperError(
        "pixelFormat cannot be DEPTH_COMPONENT, DEPTH_STENCIL or a compressed format."
      );
    }
    Check.defined("options.context", options.context);
    Check.typeOf.number.greaterThanOrEquals(
      "framebufferXOffset",
      framebufferXOffset,
      0
    );
    Check.typeOf.number.greaterThanOrEquals(
      "framebufferYOffset",
      framebufferYOffset,
      0
    );
    if (framebufferXOffset + width > gl.drawingBufferWidth) {
      throw new DeveloperError(
        "framebufferXOffset + width must be less than or equal to drawingBufferWidth"
      );
    }
    if (framebufferYOffset + height > gl.drawingBufferHeight) {
      throw new DeveloperError(
        "framebufferYOffset + height must be less than or equal to drawingBufferHeight."
      );
    }
    //>>includeEnd('debug');

    var texture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: pixelFormat,
      source: {
        framebuffer: defined(framebuffer)
          ? framebuffer
          : context.defaultFramebuffer,
        xOffset: framebufferXOffset,
        yOffset: framebufferYOffset,
        width: width,
        height: height,
      },
    });

    return texture;
  };

  Object.defineProperties(Texture.prototype, {
    /**
     * A unique id for the texture
     * @memberof Texture.prototype
     * @type {String}
     * @readonly
     * @private
     */
    id: {
      get: function () {
        return this._id;
      },
    },
    /**
     * The sampler to use when sampling this texture.
     * Create a sampler by calling {@link Sampler}.  If this
     * parameter is not specified, a default sampler is used.  The default sampler clamps texture
     * coordinates in both directions, uses linear filtering for both magnification and minification,
     * and uses a maximum anisotropy of 1.0.
     * @memberof Texture.prototype
     * @type {Object}
     */
    sampler: {
      get: function () {
        return this._sampler;
      },
      set: function (sampler) {
        var minificationFilter = sampler.minificationFilter;
        var magnificationFilter = sampler.magnificationFilter;
        var context = this._context;
        var pixelFormat = this._pixelFormat;
        var pixelDatatype = this._pixelDatatype;

        var mipmap =
          minificationFilter ===
            TextureMinificationFilter$1.NEAREST_MIPMAP_NEAREST ||
          minificationFilter ===
            TextureMinificationFilter$1.NEAREST_MIPMAP_LINEAR ||
          minificationFilter ===
            TextureMinificationFilter$1.LINEAR_MIPMAP_NEAREST ||
          minificationFilter === TextureMinificationFilter$1.LINEAR_MIPMAP_LINEAR;

        // float textures only support nearest filtering unless the linear extensions are supported, so override the sampler's settings
        if (
          (pixelDatatype === PixelDatatype$1.FLOAT &&
            !context.textureFloatLinear) ||
          (pixelDatatype === PixelDatatype$1.HALF_FLOAT &&
            !context.textureHalfFloatLinear)
        ) {
          minificationFilter = mipmap
            ? TextureMinificationFilter$1.NEAREST_MIPMAP_NEAREST
            : TextureMinificationFilter$1.NEAREST;
          magnificationFilter = TextureMagnificationFilter$1.NEAREST;
        }

        // WebGL 2 depth texture only support nearest filtering. See section 3.8.13 OpenGL ES 3 spec
        if (context.webgl2) {
          if (PixelFormat$1.isDepthFormat(pixelFormat)) {
            minificationFilter = TextureMinificationFilter$1.NEAREST;
            magnificationFilter = TextureMagnificationFilter$1.NEAREST;
          }
        }

        var gl = context._gl;
        var target = this._textureTarget;

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(target, this._texture);
        gl.texParameteri(target, gl.TEXTURE_MIN_FILTER, minificationFilter);
        gl.texParameteri(target, gl.TEXTURE_MAG_FILTER, magnificationFilter);
        gl.texParameteri(target, gl.TEXTURE_WRAP_S, sampler.wrapS);
        gl.texParameteri(target, gl.TEXTURE_WRAP_T, sampler.wrapT);
        if (defined(this._textureFilterAnisotropic)) {
          gl.texParameteri(
            target,
            this._textureFilterAnisotropic.TEXTURE_MAX_ANISOTROPY_EXT,
            sampler.maximumAnisotropy
          );
        }
        gl.bindTexture(target, null);

        this._sampler = sampler;
      },
    },
    pixelFormat: {
      get: function () {
        return this._pixelFormat;
      },
    },
    pixelDatatype: {
      get: function () {
        return this._pixelDatatype;
      },
    },
    dimensions: {
      get: function () {
        return this._dimensions;
      },
    },
    preMultiplyAlpha: {
      get: function () {
        return this._preMultiplyAlpha;
      },
    },
    flipY: {
      get: function () {
        return this._flipY;
      },
    },
    width: {
      get: function () {
        return this._width;
      },
    },
    height: {
      get: function () {
        return this._height;
      },
    },
    sizeInBytes: {
      get: function () {
        if (this._hasMipmap) {
          return Math.floor((this._sizeInBytes * 4) / 3);
        }
        return this._sizeInBytes;
      },
    },
    _target: {
      get: function () {
        return this._textureTarget;
      },
    },
  });

  /**
   * Copy new image data into this texture, from a source {@link ImageData}, {@link HTMLImageElement}, {@link HTMLCanvasElement}, or {@link HTMLVideoElement}.
   * or an object with width, height, and arrayBufferView properties.
   *
   * @param {Object} source The source {@link ImageData}, {@link HTMLImageElement}, {@link HTMLCanvasElement}, or {@link HTMLVideoElement},
   *                        or an object with width, height, and arrayBufferView properties.
   * @param {Number} [xOffset=0] The offset in the x direction within the texture to copy into.
   * @param {Number} [yOffset=0] The offset in the y direction within the texture to copy into.
   *
   * @exception {DeveloperError} Cannot call copyFrom when the texture pixel format is DEPTH_COMPONENT or DEPTH_STENCIL.
   * @exception {DeveloperError} Cannot call copyFrom with a compressed texture pixel format.
   * @exception {DeveloperError} xOffset must be greater than or equal to zero.
   * @exception {DeveloperError} yOffset must be greater than or equal to zero.
   * @exception {DeveloperError} xOffset + source.width must be less than or equal to width.
   * @exception {DeveloperError} yOffset + source.height must be less than or equal to height.
   * @exception {DeveloperError} This texture was destroyed, i.e., destroy() was called.
   *
   * @example
   * texture.copyFrom({
   *   width : 1,
   *   height : 1,
   *   arrayBufferView : new Uint8Array([255, 0, 0, 255])
   * });
   */
  Texture.prototype.copyFrom = function (source, xOffset, yOffset) {
    xOffset = defaultValue(xOffset, 0);
    yOffset = defaultValue(yOffset, 0);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("source", source);
    if (PixelFormat$1.isDepthFormat(this._pixelFormat)) {
      throw new DeveloperError(
        "Cannot call copyFrom when the texture pixel format is DEPTH_COMPONENT or DEPTH_STENCIL."
      );
    }
    if (PixelFormat$1.isCompressedFormat(this._pixelFormat)) {
      throw new DeveloperError(
        "Cannot call copyFrom with a compressed texture pixel format."
      );
    }
    Check.typeOf.number.greaterThanOrEquals("xOffset", xOffset, 0);
    Check.typeOf.number.greaterThanOrEquals("yOffset", yOffset, 0);
    Check.typeOf.number.lessThanOrEquals(
      "xOffset + source.width",
      xOffset + source.width,
      this._width
    );
    Check.typeOf.number.lessThanOrEquals(
      "yOffset + source.height",
      yOffset + source.height,
      this._height
    );
    //>>includeEnd('debug');

    var context = this._context;
    var gl = context._gl;
    var target = this._textureTarget;

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(target, this._texture);

    var width = source.width;
    var height = source.height;
    var arrayBufferView = source.arrayBufferView;

    var textureWidth = this._width;
    var textureHeight = this._height;
    var internalFormat = this._internalFormat;
    var pixelFormat = this._pixelFormat;
    var pixelDatatype = this._pixelDatatype;

    var preMultiplyAlpha = this._preMultiplyAlpha;
    var flipY = this._flipY;

    var unpackAlignment = 4;
    if (defined(arrayBufferView)) {
      unpackAlignment = PixelFormat$1.alignmentInBytes(
        pixelFormat,
        pixelDatatype,
        width
      );
    }

    gl.pixelStorei(gl.UNPACK_ALIGNMENT, unpackAlignment);

    var uploaded = false;
    if (!this._initialized) {
      if (
        xOffset === 0 &&
        yOffset === 0 &&
        width === textureWidth &&
        height === textureHeight
      ) {
        // initialize the entire texture
        if (defined(arrayBufferView)) {
          gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
          gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

          if (flipY) {
            arrayBufferView = PixelFormat$1.flipY(
              arrayBufferView,
              pixelFormat,
              pixelDatatype,
              textureWidth,
              textureHeight
            );
          }
          gl.texImage2D(
            target,
            0,
            internalFormat,
            textureWidth,
            textureHeight,
            0,
            pixelFormat,
            PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
            arrayBufferView
          );
        } else {
          // Only valid for DOM-Element uploads
          gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, preMultiplyAlpha);
          gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

          gl.texImage2D(
            target,
            0,
            internalFormat,
            pixelFormat,
            PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
            source
          );
        }
        uploaded = true;
      } else {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        // initialize the entire texture to zero
        var bufferView = PixelFormat$1.createTypedArray(
          pixelFormat,
          pixelDatatype,
          textureWidth,
          textureHeight
        );
        gl.texImage2D(
          target,
          0,
          internalFormat,
          textureWidth,
          textureHeight,
          0,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
          bufferView
        );
      }
      this._initialized = true;
    }

    if (!uploaded) {
      if (defined(arrayBufferView)) {
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        if (flipY) {
          arrayBufferView = PixelFormat$1.flipY(
            arrayBufferView,
            pixelFormat,
            pixelDatatype,
            width,
            height
          );
        }
        gl.texSubImage2D(
          target,
          0,
          xOffset,
          yOffset,
          width,
          height,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
          arrayBufferView
        );
      } else {
        // Only valid for DOM-Element uploads
        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, preMultiplyAlpha);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

        gl.texSubImage2D(
          target,
          0,
          xOffset,
          yOffset,
          pixelFormat,
          PixelDatatype$1.toWebGLConstant(pixelDatatype, context),
          source
        );
      }
    }

    gl.bindTexture(target, null);
  };

  /**
   * @param {Number} [xOffset=0] The offset in the x direction within the texture to copy into.
   * @param {Number} [yOffset=0] The offset in the y direction within the texture to copy into.
   * @param {Number} [framebufferXOffset=0] optional
   * @param {Number} [framebufferYOffset=0] optional
   * @param {Number} [width=width] optional
   * @param {Number} [height=height] optional
   *
   * @exception {DeveloperError} Cannot call copyFromFramebuffer when the texture pixel format is DEPTH_COMPONENT or DEPTH_STENCIL.
   * @exception {DeveloperError} Cannot call copyFromFramebuffer when the texture pixel data type is FLOAT.
   * @exception {DeveloperError} Cannot call copyFromFramebuffer when the texture pixel data type is HALF_FLOAT.
   * @exception {DeveloperError} Cannot call copyFrom with a compressed texture pixel format.
   * @exception {DeveloperError} This texture was destroyed, i.e., destroy() was called.
   * @exception {DeveloperError} xOffset must be greater than or equal to zero.
   * @exception {DeveloperError} yOffset must be greater than or equal to zero.
   * @exception {DeveloperError} framebufferXOffset must be greater than or equal to zero.
   * @exception {DeveloperError} framebufferYOffset must be greater than or equal to zero.
   * @exception {DeveloperError} xOffset + width must be less than or equal to width.
   * @exception {DeveloperError} yOffset + height must be less than or equal to height.
   */
  Texture.prototype.copyFromFramebuffer = function (
    xOffset,
    yOffset,
    framebufferXOffset,
    framebufferYOffset,
    width,
    height
  ) {
    xOffset = defaultValue(xOffset, 0);
    yOffset = defaultValue(yOffset, 0);
    framebufferXOffset = defaultValue(framebufferXOffset, 0);
    framebufferYOffset = defaultValue(framebufferYOffset, 0);
    width = defaultValue(width, this._width);
    height = defaultValue(height, this._height);

    //>>includeStart('debug', pragmas.debug);
    if (PixelFormat$1.isDepthFormat(this._pixelFormat)) {
      throw new DeveloperError(
        "Cannot call copyFromFramebuffer when the texture pixel format is DEPTH_COMPONENT or DEPTH_STENCIL."
      );
    }
    if (this._pixelDatatype === PixelDatatype$1.FLOAT) {
      throw new DeveloperError(
        "Cannot call copyFromFramebuffer when the texture pixel data type is FLOAT."
      );
    }
    if (this._pixelDatatype === PixelDatatype$1.HALF_FLOAT) {
      throw new DeveloperError(
        "Cannot call copyFromFramebuffer when the texture pixel data type is HALF_FLOAT."
      );
    }
    if (PixelFormat$1.isCompressedFormat(this._pixelFormat)) {
      throw new DeveloperError(
        "Cannot call copyFrom with a compressed texture pixel format."
      );
    }

    Check.typeOf.number.greaterThanOrEquals("xOffset", xOffset, 0);
    Check.typeOf.number.greaterThanOrEquals("yOffset", yOffset, 0);
    Check.typeOf.number.greaterThanOrEquals(
      "framebufferXOffset",
      framebufferXOffset,
      0
    );
    Check.typeOf.number.greaterThanOrEquals(
      "framebufferYOffset",
      framebufferYOffset,
      0
    );
    Check.typeOf.number.lessThanOrEquals(
      "xOffset + width",
      xOffset + width,
      this._width
    );
    Check.typeOf.number.lessThanOrEquals(
      "yOffset + height",
      yOffset + height,
      this._height
    );
    //>>includeEnd('debug');

    var gl = this._context._gl;
    var target = this._textureTarget;

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(target, this._texture);
    gl.copyTexSubImage2D(
      target,
      0,
      xOffset,
      yOffset,
      framebufferXOffset,
      framebufferYOffset,
      width,
      height
    );
    gl.bindTexture(target, null);
    this._initialized = true;
  };

  /**
   * @param {MipmapHint} [hint=MipmapHint.DONT_CARE] optional.
   *
   * @exception {DeveloperError} Cannot call generateMipmap when the texture pixel format is DEPTH_COMPONENT or DEPTH_STENCIL.
   * @exception {DeveloperError} Cannot call generateMipmap when the texture pixel format is a compressed format.
   * @exception {DeveloperError} hint is invalid.
   * @exception {DeveloperError} This texture's width must be a power of two to call generateMipmap().
   * @exception {DeveloperError} This texture's height must be a power of two to call generateMipmap().
   * @exception {DeveloperError} This texture was destroyed, i.e., destroy() was called.
   */
  Texture.prototype.generateMipmap = function (hint) {
    hint = defaultValue(hint, MipmapHint$1.DONT_CARE);

    //>>includeStart('debug', pragmas.debug);
    if (PixelFormat$1.isDepthFormat(this._pixelFormat)) {
      throw new DeveloperError(
        "Cannot call generateMipmap when the texture pixel format is DEPTH_COMPONENT or DEPTH_STENCIL."
      );
    }
    if (PixelFormat$1.isCompressedFormat(this._pixelFormat)) {
      throw new DeveloperError(
        "Cannot call generateMipmap with a compressed pixel format."
      );
    }
    if (this._width > 1 && !CesiumMath.isPowerOfTwo(this._width)) {
      throw new DeveloperError(
        "width must be a power of two to call generateMipmap()."
      );
    }
    if (this._height > 1 && !CesiumMath.isPowerOfTwo(this._height)) {
      throw new DeveloperError(
        "height must be a power of two to call generateMipmap()."
      );
    }
    if (!MipmapHint$1.validate(hint)) {
      throw new DeveloperError("hint is invalid.");
    }
    //>>includeEnd('debug');

    this._hasMipmap = true;

    var gl = this._context._gl;
    var target = this._textureTarget;

    gl.hint(gl.GENERATE_MIPMAP_HINT, hint);
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(target, this._texture);
    gl.generateMipmap(target);
    gl.bindTexture(target, null);
  };

  Texture.prototype.isDestroyed = function () {
    return false;
  };

  Texture.prototype.destroy = function () {
    this._context._gl.deleteTexture(this._texture);
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var AspectRampMaterial = "uniform sampler2D image;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec4 rampColor = texture2D(image, vec2(materialInput.aspect / (2.0 * czm_pi), 0.5));\n\
rampColor = czm_gammaCorrect(rampColor);\n\
material.diffuse = rampColor.rgb;\n\
material.alpha = rampColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BumpMapMaterial = "uniform sampler2D image;\n\
uniform float strength;\n\
uniform vec2 repeat;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
vec2 centerPixel = fract(repeat * st);\n\
float centerBump = texture2D(image, centerPixel).channel;\n\
float imageWidth = float(imageDimensions.x);\n\
vec2 rightPixel = fract(repeat * (st + vec2(1.0 / imageWidth, 0.0)));\n\
float rightBump = texture2D(image, rightPixel).channel;\n\
float imageHeight = float(imageDimensions.y);\n\
vec2 leftPixel = fract(repeat * (st + vec2(0.0, 1.0 / imageHeight)));\n\
float topBump = texture2D(image, leftPixel).channel;\n\
vec3 normalTangentSpace = normalize(vec3(centerBump - rightBump, centerBump - topBump, clamp(1.0 - strength, 0.1, 1.0)));\n\
vec3 normalEC = materialInput.tangentToEyeMatrix * normalTangentSpace;\n\
material.normal = normalEC;\n\
material.diffuse = vec3(0.01);\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var CheckerboardMaterial = "uniform vec4 lightColor;\n\
uniform vec4 darkColor;\n\
uniform vec2 repeat;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
float b = mod(floor(repeat.s * st.s) + floor(repeat.t * st.t), 2.0);\n\
float scaledWidth = fract(repeat.s * st.s);\n\
scaledWidth = abs(scaledWidth - floor(scaledWidth + 0.5));\n\
float scaledHeight = fract(repeat.t * st.t);\n\
scaledHeight = abs(scaledHeight - floor(scaledHeight + 0.5));\n\
float value = min(scaledWidth, scaledHeight);\n\
vec4 currentColor = mix(lightColor, darkColor, b);\n\
vec4 color = czm_antialias(lightColor, darkColor, currentColor, value, 0.03);\n\
color = czm_gammaCorrect(color);\n\
material.diffuse = color.rgb;\n\
material.alpha = color.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var DotMaterial = "uniform vec4 lightColor;\n\
uniform vec4 darkColor;\n\
uniform vec2 repeat;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
float b = smoothstep(0.3, 0.32, length(fract(repeat * materialInput.st) - 0.5));\n\
vec4 color = mix(lightColor, darkColor, b);\n\
color = czm_gammaCorrect(color);\n\
material.diffuse = color.rgb;\n\
material.alpha = color.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ElevationContourMaterial = "#ifdef GL_OES_standard_derivatives\n\
#extension GL_OES_standard_derivatives : enable\n\
#endif\n\
uniform vec4 color;\n\
uniform float spacing;\n\
uniform float width;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
float distanceToContour = mod(materialInput.height, spacing);\n\
#ifdef GL_OES_standard_derivatives\n\
float dxc = abs(dFdx(materialInput.height));\n\
float dyc = abs(dFdy(materialInput.height));\n\
float dF = max(dxc, dyc) * czm_pixelRatio * width;\n\
float alpha = (distanceToContour < dF) ? 1.0 : 0.0;\n\
#else\n\
float alpha = (distanceToContour < (czm_pixelRatio * width)) ? 1.0 : 0.0;\n\
#endif\n\
vec4 outColor = czm_gammaCorrect(vec4(color.rgb, alpha * color.a));\n\
material.diffuse = outColor.rgb;\n\
material.alpha = outColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ElevationRampMaterial = "uniform sampler2D image;\n\
uniform float minimumHeight;\n\
uniform float maximumHeight;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
float scaledHeight = clamp((materialInput.height - minimumHeight) / (maximumHeight - minimumHeight), 0.0, 1.0);\n\
vec4 rampColor = texture2D(image, vec2(scaledHeight, 0.5));\n\
rampColor = czm_gammaCorrect(rampColor);\n\
material.diffuse = rampColor.rgb;\n\
material.alpha = rampColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var FadeMaterial = "uniform vec4 fadeInColor;\n\
uniform vec4 fadeOutColor;\n\
uniform float maximumDistance;\n\
uniform bool repeat;\n\
uniform vec2 fadeDirection;\n\
uniform vec2 time;\n\
float getTime(float t, float coord)\n\
{\n\
float scalar = 1.0 / maximumDistance;\n\
float q  = distance(t, coord) * scalar;\n\
if (repeat)\n\
{\n\
float r = distance(t, coord + 1.0) * scalar;\n\
float s = distance(t, coord - 1.0) * scalar;\n\
q = min(min(r, s), q);\n\
}\n\
return clamp(q, 0.0, 1.0);\n\
}\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
float s = getTime(time.x, st.s) * fadeDirection.s;\n\
float t = getTime(time.y, st.t) * fadeDirection.t;\n\
float u = length(vec2(s, t));\n\
vec4 color = mix(fadeInColor, fadeOutColor, u);\n\
color = czm_gammaCorrect(color);\n\
material.emission = color.rgb;\n\
material.alpha = color.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var GridMaterial = "#ifdef GL_OES_standard_derivatives\n\
#extension GL_OES_standard_derivatives : enable\n\
#endif\n\
uniform vec4 color;\n\
uniform float cellAlpha;\n\
uniform vec2 lineCount;\n\
uniform vec2 lineThickness;\n\
uniform vec2 lineOffset;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
float scaledWidth = fract(lineCount.s * st.s - lineOffset.s);\n\
scaledWidth = abs(scaledWidth - floor(scaledWidth + 0.5));\n\
float scaledHeight = fract(lineCount.t * st.t - lineOffset.t);\n\
scaledHeight = abs(scaledHeight - floor(scaledHeight + 0.5));\n\
float value;\n\
#ifdef GL_OES_standard_derivatives\n\
const float fuzz = 1.2;\n\
vec2 thickness = (lineThickness * czm_pixelRatio) - 1.0;\n\
vec2 dx = abs(dFdx(st));\n\
vec2 dy = abs(dFdy(st));\n\
vec2 dF = vec2(max(dx.s, dy.s), max(dx.t, dy.t)) * lineCount;\n\
value = min(\n\
smoothstep(dF.s * thickness.s, dF.s * (fuzz + thickness.s), scaledWidth),\n\
smoothstep(dF.t * thickness.t, dF.t * (fuzz + thickness.t), scaledHeight));\n\
#else\n\
const float fuzz = 0.05;\n\
vec2 range = 0.5 - (lineThickness * 0.05);\n\
value = min(\n\
1.0 - smoothstep(range.s, range.s + fuzz, scaledWidth),\n\
1.0 - smoothstep(range.t, range.t + fuzz, scaledHeight));\n\
#endif\n\
float dRim = 1.0 - abs(dot(materialInput.normalEC, normalize(materialInput.positionToEyeEC)));\n\
float sRim = smoothstep(0.8, 1.0, dRim);\n\
value *= (1.0 - sRim);\n\
vec4 halfColor;\n\
halfColor.rgb = color.rgb * 0.5;\n\
halfColor.a = color.a * (1.0 - ((1.0 - cellAlpha) * value));\n\
halfColor = czm_gammaCorrect(halfColor);\n\
material.diffuse = halfColor.rgb;\n\
material.emission = halfColor.rgb;\n\
material.alpha = halfColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var NormalMapMaterial = "uniform sampler2D image;\n\
uniform float strength;\n\
uniform vec2 repeat;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec4 textureValue = texture2D(image, fract(repeat * materialInput.st));\n\
vec3 normalTangentSpace = textureValue.channels;\n\
normalTangentSpace.xy = normalTangentSpace.xy * 2.0 - 1.0;\n\
normalTangentSpace.z = clamp(1.0 - strength, 0.1, 1.0);\n\
normalTangentSpace = normalize(normalTangentSpace);\n\
vec3 normalEC = materialInput.tangentToEyeMatrix * normalTangentSpace;\n\
material.normal = normalEC;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineArrowMaterial = "#ifdef GL_OES_standard_derivatives\n\
#extension GL_OES_standard_derivatives : enable\n\
#endif\n\
uniform vec4 color;\n\
float getPointOnLine(vec2 p0, vec2 p1, float x)\n\
{\n\
float slope = (p0.y - p1.y) / (p0.x - p1.x);\n\
return slope * (x - p0.x) + p0.y;\n\
}\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
#ifdef GL_OES_standard_derivatives\n\
float base = 1.0 - abs(fwidth(st.s)) * 10.0 * czm_pixelRatio;\n\
#else\n\
float base = 0.975;\n\
#endif\n\
vec2 center = vec2(1.0, 0.5);\n\
float ptOnUpperLine = getPointOnLine(vec2(base, 1.0), center, st.s);\n\
float ptOnLowerLine = getPointOnLine(vec2(base, 0.0), center, st.s);\n\
float halfWidth = 0.15;\n\
float s = step(0.5 - halfWidth, st.t);\n\
s *= 1.0 - step(0.5 + halfWidth, st.t);\n\
s *= 1.0 - step(base, st.s);\n\
float t = step(base, materialInput.st.s);\n\
t *= 1.0 - step(ptOnUpperLine, st.t);\n\
t *= step(ptOnLowerLine, st.t);\n\
float dist;\n\
if (st.s < base)\n\
{\n\
float d1 = abs(st.t - (0.5 - halfWidth));\n\
float d2 = abs(st.t - (0.5 + halfWidth));\n\
dist = min(d1, d2);\n\
}\n\
else\n\
{\n\
float d1 = czm_infinity;\n\
if (st.t < 0.5 - halfWidth && st.t > 0.5 + halfWidth)\n\
{\n\
d1 = abs(st.s - base);\n\
}\n\
float d2 = abs(st.t - ptOnUpperLine);\n\
float d3 = abs(st.t - ptOnLowerLine);\n\
dist = min(min(d1, d2), d3);\n\
}\n\
vec4 outsideColor = vec4(0.0);\n\
vec4 currentColor = mix(outsideColor, color, clamp(s + t, 0.0, 1.0));\n\
vec4 outColor = czm_antialias(outsideColor, color, currentColor, dist);\n\
outColor = czm_gammaCorrect(outColor);\n\
material.diffuse = outColor.rgb;\n\
material.alpha = outColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineDashMaterial = "uniform vec4 color;\n\
uniform vec4 gapColor;\n\
uniform float dashLength;\n\
uniform float dashPattern;\n\
varying float v_polylineAngle;\n\
const float maskLength = 16.0;\n\
mat2 rotate(float rad) {\n\
float c = cos(rad);\n\
float s = sin(rad);\n\
return mat2(\n\
c, s,\n\
-s, c\n\
);\n\
}\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 pos = rotate(v_polylineAngle) * gl_FragCoord.xy;\n\
float dashPosition = fract(pos.x / (dashLength * czm_pixelRatio));\n\
float maskIndex = floor(dashPosition * maskLength);\n\
float maskTest = floor(dashPattern / pow(2.0, maskIndex));\n\
vec4 fragColor = (mod(maskTest, 2.0) < 1.0) ? gapColor : color;\n\
if (fragColor.a < 0.005) {\n\
discard;\n\
}\n\
fragColor = czm_gammaCorrect(fragColor);\n\
material.emission = fragColor.rgb;\n\
material.alpha = fragColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineGlowMaterial = "uniform vec4 color;\n\
uniform float glowPower;\n\
uniform float taperPower;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
float glow = glowPower / abs(st.t - 0.5) - (glowPower / 0.5);\n\
if (taperPower <= 0.99999) {\n\
glow *= min(1.0, taperPower / (0.5 - st.s * 0.5) - (taperPower / 0.5));\n\
}\n\
vec4 fragColor;\n\
fragColor.rgb = max(vec3(glow - 1.0 + color.rgb), color.rgb);\n\
fragColor.a = clamp(0.0, 1.0, glow) * color.a;\n\
fragColor = czm_gammaCorrect(fragColor);\n\
material.emission = fragColor.rgb;\n\
material.alpha = fragColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineOutlineMaterial = "uniform vec4 color;\n\
uniform vec4 outlineColor;\n\
uniform float outlineWidth;\n\
varying float v_width;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
float halfInteriorWidth =  0.5 * (v_width - outlineWidth) / v_width;\n\
float b = step(0.5 - halfInteriorWidth, st.t);\n\
b *= 1.0 - step(0.5 + halfInteriorWidth, st.t);\n\
float d1 = abs(st.t - (0.5 - halfInteriorWidth));\n\
float d2 = abs(st.t - (0.5 + halfInteriorWidth));\n\
float dist = min(d1, d2);\n\
vec4 currentColor = mix(outlineColor, color, b);\n\
vec4 outColor = czm_antialias(outlineColor, color, currentColor, dist);\n\
outColor = czm_gammaCorrect(outColor);\n\
material.diffuse = outColor.rgb;\n\
material.alpha = outColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var RimLightingMaterial = "uniform vec4 color;\n\
uniform vec4 rimColor;\n\
uniform float width;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
float d = 1.0 - dot(materialInput.normalEC, normalize(materialInput.positionToEyeEC));\n\
float s = smoothstep(1.0 - width, 1.0, d);\n\
vec4 outColor = czm_gammaCorrect(color);\n\
vec4 outRimColor = czm_gammaCorrect(rimColor);\n\
material.diffuse = outColor.rgb;\n\
material.emission = outRimColor.rgb * s;\n\
material.alpha = mix(outColor.a, outRimColor.a, s);\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var SlopeRampMaterial = "uniform sampler2D image;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec4 rampColor = texture2D(image, vec2(materialInput.slope / (czm_pi / 2.0), 0.5));\n\
rampColor = czm_gammaCorrect(rampColor);\n\
material.diffuse = rampColor.rgb;\n\
material.alpha = rampColor.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var StripeMaterial = "uniform vec4 evenColor;\n\
uniform vec4 oddColor;\n\
uniform float offset;\n\
uniform float repeat;\n\
uniform bool horizontal;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
float coord = mix(materialInput.st.s, materialInput.st.t, float(horizontal));\n\
float value = fract((coord - offset) * (repeat * 0.5));\n\
float dist = min(value, min(abs(value - 0.5), 1.0 - value));\n\
vec4 currentColor = mix(evenColor, oddColor, step(0.5, value));\n\
vec4 color = czm_antialias(evenColor, oddColor, currentColor, dist);\n\
color = czm_gammaCorrect(color);\n\
material.diffuse = color.rgb;\n\
material.alpha = color.a;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var WaterMaterial = "uniform sampler2D specularMap;\n\
uniform sampler2D normalMap;\n\
uniform vec4 baseWaterColor;\n\
uniform vec4 blendColor;\n\
uniform float frequency;\n\
uniform float animationSpeed;\n\
uniform float amplitude;\n\
uniform float specularIntensity;\n\
uniform float fadeFactor;\n\
czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
float time = czm_frameNumber * animationSpeed;\n\
float fade = max(1.0, (length(materialInput.positionToEyeEC) / 10000000000.0) * frequency * fadeFactor);\n\
float specularMapValue = texture2D(specularMap, materialInput.st).r;\n\
vec4 noise = czm_getWaterNoise(normalMap, materialInput.st * frequency, time, 0.0);\n\
vec3 normalTangentSpace = noise.xyz * vec3(1.0, 1.0, (1.0 / amplitude));\n\
normalTangentSpace.xy /= fade;\n\
normalTangentSpace = mix(vec3(0.0, 0.0, 50.0), normalTangentSpace, specularMapValue);\n\
normalTangentSpace = normalize(normalTangentSpace);\n\
float tsPerturbationRatio = clamp(dot(normalTangentSpace, vec3(0.0, 0.0, 1.0)), 0.0, 1.0);\n\
material.alpha = mix(blendColor.a, baseWaterColor.a, specularMapValue) * specularMapValue;\n\
material.diffuse = mix(blendColor.rgb, baseWaterColor.rgb, specularMapValue);\n\
material.diffuse += (0.1 * tsPerturbationRatio);\n\
material.diffuse = material.diffuse;\n\
material.normal = normalize(materialInput.tangentToEyeMatrix * normalTangentSpace);\n\
material.specular = specularIntensity;\n\
material.shininess = 10.0;\n\
return material;\n\
}\n\
";

  /**
   * A Material defines surface appearance through a combination of diffuse, specular,
   * normal, emission, and alpha components. These values are specified using a
   * JSON schema called Fabric which gets parsed and assembled into glsl shader code
   * behind-the-scenes. Check out the {@link https://github.com/CesiumGS/cesium/wiki/Fabric|wiki page}
   * for more details on Fabric.
   * <br /><br />
   * <style type="text/css">
   *  #materialDescriptions code {
   *      font-weight: normal;
   *      font-family: Consolas, 'Lucida Console', Monaco, monospace;
   *      color: #A35A00;
   *  }
   *  #materialDescriptions ul, #materialDescriptions ul ul {
   *      list-style-type: none;
   *  }
   *  #materialDescriptions ul ul {
   *      margin-bottom: 10px;
   *  }
   *  #materialDescriptions ul ul li {
   *      font-weight: normal;
   *      color: #000000;
   *      text-indent: -2em;
   *      margin-left: 2em;
   *  }
   *  #materialDescriptions ul li {
   *      font-weight: bold;
   *      color: #0053CF;
   *  }
   * </style>
   *
   * Base material types and their uniforms:
   * <div id='materialDescriptions'>
   * <ul>
   *  <li>Color</li>
   *  <ul>
   *      <li><code>color</code>:  rgba color object.</li>
   *  </ul>
   *  <li>Image</li>
   *  <ul>
   *      <li><code>image</code>:  path to image.</li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of times to repeat the image.</li>
   *  </ul>
   *  <li>DiffuseMap</li>
   *  <ul>
   *      <li><code>image</code>:  path to image.</li>
   *      <li><code>channels</code>:  Three character string containing any combination of r, g, b, and a for selecting the desired image channels.</li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of times to repeat the image.</li>
   *  </ul>
   *  <li>AlphaMap</li>
   *  <ul>
   *      <li><code>image</code>:  path to image.</li>
   *      <li><code>channel</code>:  One character string containing r, g, b, or a for selecting the desired image channel. </li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of times to repeat the image.</li>
   *  </ul>
   *  <li>SpecularMap</li>
   *  <ul>
   *      <li><code>image</code>: path to image.</li>
   *      <li><code>channel</code>: One character string containing r, g, b, or a for selecting the desired image channel. </li>
   *      <li><code>repeat</code>: Object with x and y values specifying the number of times to repeat the image.</li>
   *  </ul>
   *  <li>EmissionMap</li>
   *  <ul>
   *      <li><code>image</code>:  path to image.</li>
   *      <li><code>channels</code>:  Three character string containing any combination of r, g, b, and a for selecting the desired image channels. </li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of times to repeat the image.</li>
   *  </ul>
   *  <li>BumpMap</li>
   *  <ul>
   *      <li><code>image</code>:  path to image.</li>
   *      <li><code>channel</code>:  One character string containing r, g, b, or a for selecting the desired image channel. </li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of times to repeat the image.</li>
   *      <li><code>strength</code>:  Bump strength value between 0.0 and 1.0 where 0.0 is small bumps and 1.0 is large bumps.</li>
   *  </ul>
   *  <li>NormalMap</li>
   *  <ul>
   *      <li><code>image</code>:  path to image.</li>
   *      <li><code>channels</code>:  Three character string containing any combination of r, g, b, and a for selecting the desired image channels. </li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of times to repeat the image.</li>
   *      <li><code>strength</code>:  Bump strength value between 0.0 and 1.0 where 0.0 is small bumps and 1.0 is large bumps.</li>
   *  </ul>
   *  <li>Grid</li>
   *  <ul>
   *      <li><code>color</code>:  rgba color object for the whole material.</li>
   *      <li><code>cellAlpha</code>: Alpha value for the cells between grid lines.  This will be combined with color.alpha.</li>
   *      <li><code>lineCount</code>:  Object with x and y values specifying the number of columns and rows respectively.</li>
   *      <li><code>lineThickness</code>:  Object with x and y values specifying the thickness of grid lines (in pixels where available).</li>
   *      <li><code>lineOffset</code>:  Object with x and y values specifying the offset of grid lines (range is 0 to 1).</li>
   *  </ul>
   *  <li>Stripe</li>
   *  <ul>
   *      <li><code>horizontal</code>:  Boolean that determines if the stripes are horizontal or vertical.</li>
   *      <li><code>evenColor</code>:  rgba color object for the stripe's first color.</li>
   *      <li><code>oddColor</code>:  rgba color object for the stripe's second color.</li>
   *      <li><code>offset</code>:  Number that controls at which point into the pattern to begin drawing; with 0.0 being the beginning of the even color, 1.0 the beginning of the odd color, 2.0 being the even color again, and any multiple or fractional values being in between.</li>
   *      <li><code>repeat</code>:  Number that controls the total number of stripes, half light and half dark.</li>
   *  </ul>
   *  <li>Checkerboard</li>
   *  <ul>
   *      <li><code>lightColor</code>:  rgba color object for the checkerboard's light alternating color.</li>
   *      <li><code>darkColor</code>: rgba color object for the checkerboard's dark alternating color.</li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of columns and rows respectively.</li>
   *  </ul>
   *  <li>Dot</li>
   *  <ul>
   *      <li><code>lightColor</code>:  rgba color object for the dot color.</li>
   *      <li><code>darkColor</code>:  rgba color object for the background color.</li>
   *      <li><code>repeat</code>:  Object with x and y values specifying the number of columns and rows of dots respectively.</li>
   *  </ul>
   *  <li>Water</li>
   *  <ul>
   *      <li><code>baseWaterColor</code>:  rgba color object base color of the water.</li>
   *      <li><code>blendColor</code>:  rgba color object used when blending from water to non-water areas.</li>
   *      <li><code>specularMap</code>:  Single channel texture used to indicate areas of water.</li>
   *      <li><code>normalMap</code>:  Normal map for water normal perturbation.</li>
   *      <li><code>frequency</code>:  Number that controls the number of waves.</li>
   *      <li><code>normalMap</code>:  Normal map for water normal perturbation.</li>
   *      <li><code>animationSpeed</code>:  Number that controls the animations speed of the water.</li>
   *      <li><code>amplitude</code>:  Number that controls the amplitude of water waves.</li>
   *      <li><code>specularIntensity</code>:  Number that controls the intensity of specular reflections.</li>
   *  </ul>
   *  <li>RimLighting</li>
   *  <ul>
   *      <li><code>color</code>:  diffuse color and alpha.</li>
   *      <li><code>rimColor</code>:  diffuse color and alpha of the rim.</li>
   *      <li><code>width</code>:  Number that determines the rim's width.</li>
   *  </ul>
   *  <li>Fade</li>
   *  <ul>
   *      <li><code>fadeInColor</code>: diffuse color and alpha at <code>time</code></li>
   *      <li><code>fadeOutColor</code>: diffuse color and alpha at <code>maximumDistance</code> from <code>time</code></li>
   *      <li><code>maximumDistance</code>: Number between 0.0 and 1.0 where the <code>fadeInColor</code> becomes the <code>fadeOutColor</code>. A value of 0.0 gives the entire material a color of <code>fadeOutColor</code> and a value of 1.0 gives the the entire material a color of <code>fadeInColor</code></li>
   *      <li><code>repeat</code>: true if the fade should wrap around the texture coodinates.</li>
   *      <li><code>fadeDirection</code>: Object with x and y values specifying if the fade should be in the x and y directions.</li>
   *      <li><code>time</code>: Object with x and y values between 0.0 and 1.0 of the <code>fadeInColor</code> position</li>
   *  </ul>
   *  <li>PolylineArrow</li>
   *  <ul>
   *      <li><code>color</code>: diffuse color and alpha.</li>
   *  </ul>
   *  <li>PolylineDash</li>
   *  <ul>
   *      <li><code>color</code>: color for the line.</li>
   *      <li><code>gapColor</code>: color for the gaps in the line.</li>
   *      <li><code>dashLength</code>: Dash length in pixels.</li>
   *      <li><code>dashPattern</code>: The 16 bit stipple pattern for the line..</li>
   *  </ul>
   *  <li>PolylineGlow</li>
   *  <ul>
   *      <li><code>color</code>: color and maximum alpha for the glow on the line.</li>
   *      <li><code>glowPower</code>: strength of the glow, as a percentage of the total line width (less than 1.0).</li>
   *      <li><code>taperPower</code>: strength of the tapering effect, as a percentage of the total line length.  If 1.0 or higher, no taper effect is used.</li>
   *  </ul>
   *  <li>PolylineOutline</li>
   *  <ul>
   *      <li><code>color</code>: diffuse color and alpha for the interior of the line.</li>
   *      <li><code>outlineColor</code>: diffuse color and alpha for the outline.</li>
   *      <li><code>outlineWidth</code>: width of the outline in pixels.</li>
   *  </ul>
   *  <li>ElevationContour</li>
   *  <ul>
   *      <li><code>color</code>: color and alpha for the contour line.</li>
   *      <li><code>spacing</code>: spacing for contour lines in meters.</li>
   *      <li><code>width</code>: Number specifying the width of the grid lines in pixels.</li>
   *  </ul>
   *  <li>ElevationRamp</li>
   *  <ul>
   *      <li><code>image</code>: color ramp image to use for coloring the terrain.</li>
   *      <li><code>minimumHeight</code>: minimum height for the ramp.</li>
   *      <li><code>maximumHeight</code>: maximum height for the ramp.</li>
   *  </ul>
   *  <li>SlopeRamp</li>
   *  <ul>
   *      <li><code>image</code>: color ramp image to use for coloring the terrain by slope.</li>
   *  </ul>
   *  <li>AspectRamp</li>
   *  <ul>
   *      <li><code>image</code>: color ramp image to use for color the terrain by aspect.</li>
   *  </ul>
   * </ul>
   * </ul>
   * </div>
   *
   * @alias Material
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.strict=false] Throws errors for issues that would normally be ignored, including unused uniforms or materials.
   * @param {Boolean|Function} [options.translucent=true] When <code>true</code> or a function that returns <code>true</code>, the geometry
   *                           with this material is expected to appear translucent.
   * @param {TextureMinificationFilter} [options.minificationFilter=TextureMinificationFilter.LINEAR] The {@link TextureMinificationFilter} to apply to this material's textures.
   * @param {TextureMagnificationFilter} [options.magnificationFilter=TextureMagnificationFilter.LINEAR] The {@link TextureMagnificationFilter} to apply to this material's textures.
   * @param {Object} options.fabric The fabric JSON used to generate the material.
   *
   * @constructor
   *
   * @exception {DeveloperError} fabric: uniform has invalid type.
   * @exception {DeveloperError} fabric: uniforms and materials cannot share the same property.
   * @exception {DeveloperError} fabric: cannot have source and components in the same section.
   * @exception {DeveloperError} fabric: property name is not valid. It should be 'type', 'materials', 'uniforms', 'components', or 'source'.
   * @exception {DeveloperError} fabric: property name is not valid. It should be 'diffuse', 'specular', 'shininess', 'normal', 'emission', or 'alpha'.
   * @exception {DeveloperError} strict: shader source does not use string.
   * @exception {DeveloperError} strict: shader source does not use uniform.
   * @exception {DeveloperError} strict: shader source does not use material.
   *
   * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric wiki page} for a more detailed options of Fabric.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Materials.html|Cesium Sandcastle Materials Demo}
   *
   * @example
   * // Create a color material with fromType:
   * polygon.material = Cesium.Material.fromType('Color');
   * polygon.material.uniforms.color = new Cesium.Color(1.0, 1.0, 0.0, 1.0);
   *
   * // Create the default material:
   * polygon.material = new Cesium.Material();
   *
   * // Create a color material with full Fabric notation:
   * polygon.material = new Cesium.Material({
   *     fabric : {
   *         type : 'Color',
   *         uniforms : {
   *             color : new Cesium.Color(1.0, 1.0, 0.0, 1.0)
   *         }
   *     }
   * });
   */
  function Material(options) {
    /**
     * The material type. Can be an existing type or a new type. If no type is specified in fabric, type is a GUID.
     * @type {String}
     * @default undefined
     */
    this.type = undefined;

    /**
     * The glsl shader source for this material.
     * @type {String}
     * @default undefined
     */
    this.shaderSource = undefined;

    /**
     * Maps sub-material names to Material objects.
     * @type {Object}
     * @default undefined
     */
    this.materials = undefined;

    /**
     * Maps uniform names to their values.
     * @type {Object}
     * @default undefined
     */
    this.uniforms = undefined;
    this._uniforms = undefined;

    /**
     * When <code>true</code> or a function that returns <code>true</code>,
     * the geometry is expected to appear translucent.
     * @type {Boolean|Function}
     * @default undefined
     */
    this.translucent = undefined;

    this._minificationFilter = defaultValue(
      options.minificationFilter,
      TextureMinificationFilter$1.LINEAR
    );
    this._magnificationFilter = defaultValue(
      options.magnificationFilter,
      TextureMagnificationFilter$1.LINEAR
    );

    this._strict = undefined;
    this._template = undefined;
    this._count = undefined;

    this._texturePaths = {};
    this._loadedImages = [];
    this._loadedCubeMaps = [];

    this._textures = {};

    this._updateFunctions = [];

    this._defaultTexture = undefined;

    initializeMaterial(options, this);
    Object.defineProperties(this, {
      type: {
        value: this.type,
        writable: false,
      },
    });

    if (!defined(Material._uniformList[this.type])) {
      Material._uniformList[this.type] = Object.keys(this._uniforms);
    }
  }

  // Cached list of combined uniform names indexed by type.
  // Used to get the list of uniforms in the same order.
  Material._uniformList = {};

  /**
   * Creates a new material using an existing material type.
   * <br /><br />
   * Shorthand for: new Material({fabric : {type : type}});
   *
   * @param {String} type The base material type.
   * @param {Object} [uniforms] Overrides for the default uniforms.
   * @returns {Material} New material object.
   *
   * @exception {DeveloperError} material with that type does not exist.
   *
   * @example
   * var material = Cesium.Material.fromType('Color', {
   *     color : new Cesium.Color(1.0, 0.0, 0.0, 1.0)
   * });
   */
  Material.fromType = function (type, uniforms) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(Material._materialCache.getMaterial(type))) {
      throw new DeveloperError(
        "material with type '" + type + "' does not exist."
      );
    }
    //>>includeEnd('debug');

    var material = new Material({
      fabric: {
        type: type,
      },
    });

    if (defined(uniforms)) {
      for (var name in uniforms) {
        if (uniforms.hasOwnProperty(name)) {
          material.uniforms[name] = uniforms[name];
        }
      }
    }

    return material;
  };

  /**
   * Gets whether or not this material is translucent.
   * @returns {Boolean} <code>true</code> if this material is translucent, <code>false</code> otherwise.
   */
  Material.prototype.isTranslucent = function () {
    if (defined(this.translucent)) {
      if (typeof this.translucent === "function") {
        return this.translucent();
      }

      return this.translucent;
    }

    var translucent = true;
    var funcs = this._translucentFunctions;
    var length = funcs.length;
    for (var i = 0; i < length; ++i) {
      var func = funcs[i];
      if (typeof func === "function") {
        translucent = translucent && func();
      } else {
        translucent = translucent && func;
      }

      if (!translucent) {
        break;
      }
    }
    return translucent;
  };

  /**
   * @private
   */
  Material.prototype.update = function (context) {
    var i;
    var uniformId;

    var loadedImages = this._loadedImages;
    var length = loadedImages.length;

    for (i = 0; i < length; ++i) {
      var loadedImage = loadedImages[i];
      uniformId = loadedImage.id;
      var image = loadedImage.image;

      var sampler = new Sampler({
        minificationFilter: this._minificationFilter,
        magnificationFilter: this._magnificationFilter,
      });

      var texture;
      if (defined(image.internalFormat)) {
        texture = new Texture({
          context: context,
          pixelFormat: image.internalFormat,
          width: image.width,
          height: image.height,
          source: {
            arrayBufferView: image.bufferView,
          },
          sampler: sampler,
        });
      } else {
        texture = new Texture({
          context: context,
          source: image,
          sampler: sampler,
        });
      }

      this._textures[uniformId] = texture;

      var uniformDimensionsName = uniformId + "Dimensions";
      if (this.uniforms.hasOwnProperty(uniformDimensionsName)) {
        var uniformDimensions = this.uniforms[uniformDimensionsName];
        uniformDimensions.x = texture._width;
        uniformDimensions.y = texture._height;
      }
    }

    loadedImages.length = 0;

    var loadedCubeMaps = this._loadedCubeMaps;
    length = loadedCubeMaps.length;

    for (i = 0; i < length; ++i) {
      var loadedCubeMap = loadedCubeMaps[i];
      uniformId = loadedCubeMap.id;
      var images = loadedCubeMap.images;

      var cubeMap = new CubeMap({
        context: context,
        source: {
          positiveX: images[0],
          negativeX: images[1],
          positiveY: images[2],
          negativeY: images[3],
          positiveZ: images[4],
          negativeZ: images[5],
        },
        sampler: new Sampler({
          minificationFilter: this._minificationFilter,
          magnificationFilter: this._magnificationFilter,
        }),
      });

      this._textures[uniformId] = cubeMap;
    }

    loadedCubeMaps.length = 0;

    var updateFunctions = this._updateFunctions;
    length = updateFunctions.length;
    for (i = 0; i < length; ++i) {
      updateFunctions[i](this, context);
    }

    var subMaterials = this.materials;
    for (var name in subMaterials) {
      if (subMaterials.hasOwnProperty(name)) {
        subMaterials[name].update(context);
      }
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see Material#destroy
   */
  Material.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * material = material && material.destroy();
   *
   * @see Material#isDestroyed
   */
  Material.prototype.destroy = function () {
    var textures = this._textures;
    for (var texture in textures) {
      if (textures.hasOwnProperty(texture)) {
        var instance = textures[texture];
        if (instance !== this._defaultTexture) {
          instance.destroy();
        }
      }
    }

    var materials = this.materials;
    for (var material in materials) {
      if (materials.hasOwnProperty(material)) {
        materials[material].destroy();
      }
    }
    return destroyObject(this);
  };

  function initializeMaterial(options, result) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    result._strict = defaultValue(options.strict, false);
    result._count = defaultValue(options.count, 0);
    result._template = clone(
      defaultValue(options.fabric, defaultValue.EMPTY_OBJECT)
    );
    result._template.uniforms = clone(
      defaultValue(result._template.uniforms, defaultValue.EMPTY_OBJECT)
    );
    result._template.materials = clone(
      defaultValue(result._template.materials, defaultValue.EMPTY_OBJECT)
    );

    result.type = defined(result._template.type)
      ? result._template.type
      : createGuid();

    result.shaderSource = "";
    result.materials = {};
    result.uniforms = {};
    result._uniforms = {};
    result._translucentFunctions = [];

    var translucent;

    // If the cache contains this material type, build the material template off of the stored template.
    var cachedMaterial = Material._materialCache.getMaterial(result.type);
    if (defined(cachedMaterial)) {
      var template = clone(cachedMaterial.fabric, true);
      result._template = combine(result._template, template, true);
      translucent = cachedMaterial.translucent;
    }

    // Make sure the template has no obvious errors. More error checking happens later.
    checkForTemplateErrors(result);

    // If the material has a new type, add it to the cache.
    if (!defined(cachedMaterial)) {
      Material._materialCache.addMaterial(result.type, result);
    }

    createMethodDefinition(result);
    createUniforms(result);
    createSubMaterials(result);

    var defaultTranslucent =
      result._translucentFunctions.length === 0 ? true : undefined;
    translucent = defaultValue(translucent, defaultTranslucent);
    translucent = defaultValue(options.translucent, translucent);

    if (defined(translucent)) {
      if (typeof translucent === "function") {
        var wrappedTranslucent = function () {
          return translucent(result);
        };
        result._translucentFunctions.push(wrappedTranslucent);
      } else {
        result._translucentFunctions.push(translucent);
      }
    }
  }

  function checkForValidProperties(object, properties, result, throwNotFound) {
    if (defined(object)) {
      for (var property in object) {
        if (object.hasOwnProperty(property)) {
          var hasProperty = properties.indexOf(property) !== -1;
          if (
            (throwNotFound && !hasProperty) ||
            (!throwNotFound && hasProperty)
          ) {
            result(property, properties);
          }
        }
      }
    }
  }

  function invalidNameError(property, properties) {
    //>>includeStart('debug', pragmas.debug);
    var errorString =
      "fabric: property name '" + property + "' is not valid. It should be ";
    for (var i = 0; i < properties.length; i++) {
      var propertyName = "'" + properties[i] + "'";
      errorString +=
        i === properties.length - 1
          ? "or " + propertyName + "."
          : propertyName + ", ";
    }
    throw new DeveloperError(errorString);
    //>>includeEnd('debug');
  }

  function duplicateNameError(property, properties) {
    //>>includeStart('debug', pragmas.debug);
    var errorString =
      "fabric: uniforms and materials cannot share the same property '" +
      property +
      "'";
    throw new DeveloperError(errorString);
    //>>includeEnd('debug');
  }

  var templateProperties = [
    "type",
    "materials",
    "uniforms",
    "components",
    "source",
  ];
  var componentProperties = [
    "diffuse",
    "specular",
    "shininess",
    "normal",
    "emission",
    "alpha",
  ];

  function checkForTemplateErrors(material) {
    var template = material._template;
    var uniforms = template.uniforms;
    var materials = template.materials;
    var components = template.components;

    // Make sure source and components do not exist in the same template.
    //>>includeStart('debug', pragmas.debug);
    if (defined(components) && defined(template.source)) {
      throw new DeveloperError(
        "fabric: cannot have source and components in the same template."
      );
    }
    //>>includeEnd('debug');

    // Make sure all template and components properties are valid.
    checkForValidProperties(template, templateProperties, invalidNameError, true);
    checkForValidProperties(
      components,
      componentProperties,
      invalidNameError,
      true
    );

    // Make sure uniforms and materials do not share any of the same names.
    var materialNames = [];
    for (var property in materials) {
      if (materials.hasOwnProperty(property)) {
        materialNames.push(property);
      }
    }
    checkForValidProperties(uniforms, materialNames, duplicateNameError, false);
  }

  function isMaterialFused(shaderComponent, material) {
    var materials = material._template.materials;
    for (var subMaterialId in materials) {
      if (materials.hasOwnProperty(subMaterialId)) {
        if (shaderComponent.indexOf(subMaterialId) > -1) {
          return true;
        }
      }
    }

    return false;
  }

  // Create the czm_getMaterial method body using source or components.
  function createMethodDefinition(material) {
    var components = material._template.components;
    var source = material._template.source;
    if (defined(source)) {
      material.shaderSource += source + "\n";
    } else {
      material.shaderSource +=
        "czm_material czm_getMaterial(czm_materialInput materialInput)\n{\n";
      material.shaderSource +=
        "czm_material material = czm_getDefaultMaterial(materialInput);\n";
      if (defined(components)) {
        var isMultiMaterial =
          Object.keys(material._template.materials).length > 0;
        for (var component in components) {
          if (components.hasOwnProperty(component)) {
            if (component === "diffuse" || component === "emission") {
              var isFusion =
                isMultiMaterial &&
                isMaterialFused(components[component], material);
              var componentSource = isFusion
                ? components[component]
                : "czm_gammaCorrect(" + components[component] + ")";
              material.shaderSource +=
                "material." + component + " = " + componentSource + "; \n";
            } else if (component === "alpha") {
              material.shaderSource +=
                "material.alpha = " + components.alpha + "; \n";
            } else {
              material.shaderSource +=
                "material." + component + " = " + components[component] + ";\n";
            }
          }
        }
      }
      material.shaderSource += "return material;\n}\n";
    }
  }

  var matrixMap = {
    mat2: Matrix2,
    mat3: Matrix3,
    mat4: Matrix4,
  };

  var ktxRegex = /\.ktx$/i;
  var crnRegex = /\.crn$/i;

  function createTexture2DUpdateFunction(uniformId) {
    var oldUniformValue;
    return function (material, context) {
      var uniforms = material.uniforms;
      var uniformValue = uniforms[uniformId];
      var uniformChanged = oldUniformValue !== uniformValue;
      oldUniformValue = uniformValue;
      var texture = material._textures[uniformId];

      var uniformDimensionsName;
      var uniformDimensions;

      if (uniformValue instanceof HTMLVideoElement) {
        // HTMLVideoElement.readyState >=2 means we have enough data for the current frame.
        // See: https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/readyState
        if (uniformValue.readyState >= 2) {
          if (uniformChanged && defined(texture)) {
            if (texture !== context.defaultTexture) {
              texture.destroy();
            }
            texture = undefined;
          }

          if (!defined(texture) || texture === context.defaultTexture) {
            var sampler = new Sampler({
              minificationFilter: material._minificationFilter,
              magnificationFilter: material._magnificationFilter,
            });
            texture = new Texture({
              context: context,
              source: uniformValue,
              sampler: sampler,
            });
            material._textures[uniformId] = texture;
            return;
          }

          texture.copyFrom(uniformValue);
        } else if (!defined(texture)) {
          material._textures[uniformId] = context.defaultTexture;
        }
        return;
      }

      if (uniformValue instanceof Texture && uniformValue !== texture) {
        material._texturePaths[uniformId] = undefined;
        var tmp = material._textures[uniformId];
        if (tmp !== material._defaultTexture) {
          tmp.destroy();
        }
        material._textures[uniformId] = uniformValue;

        uniformDimensionsName = uniformId + "Dimensions";
        if (uniforms.hasOwnProperty(uniformDimensionsName)) {
          uniformDimensions = uniforms[uniformDimensionsName];
          uniformDimensions.x = uniformValue._width;
          uniformDimensions.y = uniformValue._height;
        }

        return;
      }

      if (!defined(texture)) {
        material._texturePaths[uniformId] = undefined;
        if (!defined(material._defaultTexture)) {
          material._defaultTexture = context.defaultTexture;
        }
        texture = material._textures[uniformId] = material._defaultTexture;

        uniformDimensionsName = uniformId + "Dimensions";
        if (uniforms.hasOwnProperty(uniformDimensionsName)) {
          uniformDimensions = uniforms[uniformDimensionsName];
          uniformDimensions.x = texture._width;
          uniformDimensions.y = texture._height;
        }
      }

      if (uniformValue === Material.DefaultImageId) {
        return;
      }

      // When using the entity layer, the Resource objects get recreated on getValue because
      //  they are clonable. That's why we check the url property for Resources
      //  because the instances aren't the same and we keep trying to load the same
      //  image if it fails to load.
      var isResource = uniformValue instanceof Resource;
      if (
        !defined(material._texturePaths[uniformId]) ||
        (isResource &&
          uniformValue.url !== material._texturePaths[uniformId].url) ||
        (!isResource && uniformValue !== material._texturePaths[uniformId])
      ) {
        if (typeof uniformValue === "string" || isResource) {
          var resource = isResource
            ? uniformValue
            : Resource.createIfNeeded(uniformValue);

          var promise;
          if (ktxRegex.test(resource.url)) {
            promise = loadKTX(resource);
          } else if (crnRegex.test(resource.url)) {
            promise = loadCRN(resource);
          } else {
            promise = resource.fetchImage();
          }
          when(promise, function (image) {
            material._loadedImages.push({
              id: uniformId,
              image: image,
            });
          });
        } else if (
          uniformValue instanceof HTMLCanvasElement ||
          uniformValue instanceof HTMLImageElement
        ) {
          material._loadedImages.push({
            id: uniformId,
            image: uniformValue,
          });
        }

        material._texturePaths[uniformId] = uniformValue;
      }
    };
  }

  function createCubeMapUpdateFunction(uniformId) {
    return function (material, context) {
      var uniformValue = material.uniforms[uniformId];

      if (uniformValue instanceof CubeMap) {
        var tmp = material._textures[uniformId];
        if (tmp !== material._defaultTexture) {
          tmp.destroy();
        }
        material._texturePaths[uniformId] = undefined;
        material._textures[uniformId] = uniformValue;
        return;
      }

      if (!defined(material._textures[uniformId])) {
        material._texturePaths[uniformId] = undefined;
        material._textures[uniformId] = context.defaultCubeMap;
      }

      if (uniformValue === Material.DefaultCubeMapId) {
        return;
      }

      var path =
        uniformValue.positiveX +
        uniformValue.negativeX +
        uniformValue.positiveY +
        uniformValue.negativeY +
        uniformValue.positiveZ +
        uniformValue.negativeZ;

      if (path !== material._texturePaths[uniformId]) {
        var promises = [
          Resource.createIfNeeded(uniformValue.positiveX).fetchImage(),
          Resource.createIfNeeded(uniformValue.negativeX).fetchImage(),
          Resource.createIfNeeded(uniformValue.positiveY).fetchImage(),
          Resource.createIfNeeded(uniformValue.negativeY).fetchImage(),
          Resource.createIfNeeded(uniformValue.positiveZ).fetchImage(),
          Resource.createIfNeeded(uniformValue.negativeZ).fetchImage(),
        ];

        when.all(promises).then(function (images) {
          material._loadedCubeMaps.push({
            id: uniformId,
            images: images,
          });
        });

        material._texturePaths[uniformId] = path;
      }
    };
  }

  function createUniforms(material) {
    var uniforms = material._template.uniforms;
    for (var uniformId in uniforms) {
      if (uniforms.hasOwnProperty(uniformId)) {
        createUniform(material, uniformId);
      }
    }
  }

  // Writes uniform declarations to the shader file and connects uniform values with
  // corresponding material properties through the returnUniforms function.
  function createUniform(material, uniformId) {
    var strict = material._strict;
    var materialUniforms = material._template.uniforms;
    var uniformValue = materialUniforms[uniformId];
    var uniformType = getUniformType(uniformValue);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(uniformType)) {
      throw new DeveloperError(
        "fabric: uniform '" + uniformId + "' has invalid type."
      );
    }
    //>>includeEnd('debug');

    var replacedTokenCount;
    if (uniformType === "channels") {
      replacedTokenCount = replaceToken(material, uniformId, uniformValue, false);
      //>>includeStart('debug', pragmas.debug);
      if (replacedTokenCount === 0 && strict) {
        throw new DeveloperError(
          "strict: shader source does not use channels '" + uniformId + "'."
        );
      }
      //>>includeEnd('debug');
    } else {
      // Since webgl doesn't allow texture dimension queries in glsl, create a uniform to do it.
      // Check if the shader source actually uses texture dimensions before creating the uniform.
      if (uniformType === "sampler2D") {
        var imageDimensionsUniformName = uniformId + "Dimensions";
        if (getNumberOfTokens(material, imageDimensionsUniformName) > 0) {
          materialUniforms[imageDimensionsUniformName] = {
            type: "ivec3",
            x: 1,
            y: 1,
          };
          createUniform(material, imageDimensionsUniformName);
        }
      }

      // Add uniform declaration to source code.
      var uniformDeclarationRegex = new RegExp(
        "uniform\\s+" + uniformType + "\\s+" + uniformId + "\\s*;"
      );
      if (!uniformDeclarationRegex.test(material.shaderSource)) {
        var uniformDeclaration = "uniform " + uniformType + " " + uniformId + ";";
        material.shaderSource = uniformDeclaration + material.shaderSource;
      }

      var newUniformId = uniformId + "_" + material._count++;
      replacedTokenCount = replaceToken(material, uniformId, newUniformId);
      //>>includeStart('debug', pragmas.debug);
      if (replacedTokenCount === 1 && strict) {
        throw new DeveloperError(
          "strict: shader source does not use uniform '" + uniformId + "'."
        );
      }
      //>>includeEnd('debug');

      // Set uniform value
      material.uniforms[uniformId] = uniformValue;

      if (uniformType === "sampler2D") {
        material._uniforms[newUniformId] = function () {
          return material._textures[uniformId];
        };
        material._updateFunctions.push(createTexture2DUpdateFunction(uniformId));
      } else if (uniformType === "samplerCube") {
        material._uniforms[newUniformId] = function () {
          return material._textures[uniformId];
        };
        material._updateFunctions.push(createCubeMapUpdateFunction(uniformId));
      } else if (uniformType.indexOf("mat") !== -1) {
        var scratchMatrix = new matrixMap[uniformType]();
        material._uniforms[newUniformId] = function () {
          return matrixMap[uniformType].fromColumnMajorArray(
            material.uniforms[uniformId],
            scratchMatrix
          );
        };
      } else {
        material._uniforms[newUniformId] = function () {
          return material.uniforms[uniformId];
        };
      }
    }
  }

  // Determines the uniform type based on the uniform in the template.
  function getUniformType(uniformValue) {
    var uniformType = uniformValue.type;
    if (!defined(uniformType)) {
      var type = typeof uniformValue;
      if (type === "number") {
        uniformType = "float";
      } else if (type === "boolean") {
        uniformType = "bool";
      } else if (
        type === "string" ||
        uniformValue instanceof Resource ||
        uniformValue instanceof HTMLCanvasElement ||
        uniformValue instanceof HTMLImageElement
      ) {
        if (/^([rgba]){1,4}$/i.test(uniformValue)) {
          uniformType = "channels";
        } else if (uniformValue === Material.DefaultCubeMapId) {
          uniformType = "samplerCube";
        } else {
          uniformType = "sampler2D";
        }
      } else if (type === "object") {
        if (Array.isArray(uniformValue)) {
          if (
            uniformValue.length === 4 ||
            uniformValue.length === 9 ||
            uniformValue.length === 16
          ) {
            uniformType = "mat" + Math.sqrt(uniformValue.length);
          }
        } else {
          var numAttributes = 0;
          for (var attribute in uniformValue) {
            if (uniformValue.hasOwnProperty(attribute)) {
              numAttributes += 1;
            }
          }
          if (numAttributes >= 2 && numAttributes <= 4) {
            uniformType = "vec" + numAttributes;
          } else if (numAttributes === 6) {
            uniformType = "samplerCube";
          }
        }
      }
    }
    return uniformType;
  }

  // Create all sub-materials by combining source and uniforms together.
  function createSubMaterials(material) {
    var strict = material._strict;
    var subMaterialTemplates = material._template.materials;
    for (var subMaterialId in subMaterialTemplates) {
      if (subMaterialTemplates.hasOwnProperty(subMaterialId)) {
        // Construct the sub-material.
        var subMaterial = new Material({
          strict: strict,
          fabric: subMaterialTemplates[subMaterialId],
          count: material._count,
        });

        material._count = subMaterial._count;
        material._uniforms = combine(
          material._uniforms,
          subMaterial._uniforms,
          true
        );
        material.materials[subMaterialId] = subMaterial;
        material._translucentFunctions = material._translucentFunctions.concat(
          subMaterial._translucentFunctions
        );

        // Make the material's czm_getMaterial unique by appending the sub-material type.
        var originalMethodName = "czm_getMaterial";
        var newMethodName = originalMethodName + "_" + material._count++;
        replaceToken(subMaterial, originalMethodName, newMethodName);
        material.shaderSource = subMaterial.shaderSource + material.shaderSource;

        // Replace each material id with an czm_getMaterial method call.
        var materialMethodCall = newMethodName + "(materialInput)";
        var tokensReplacedCount = replaceToken(
          material,
          subMaterialId,
          materialMethodCall
        );
        //>>includeStart('debug', pragmas.debug);
        if (tokensReplacedCount === 0 && strict) {
          throw new DeveloperError(
            "strict: shader source does not use material '" + subMaterialId + "'."
          );
        }
        //>>includeEnd('debug');
      }
    }
  }

  // Used for searching or replacing a token in a material's shader source with something else.
  // If excludePeriod is true, do not accept tokens that are preceded by periods.
  // http://stackoverflow.com/questions/641407/javascript-negative-lookbehind-equivalent
  function replaceToken(material, token, newToken, excludePeriod) {
    excludePeriod = defaultValue(excludePeriod, true);
    var count = 0;
    var suffixChars = "([\\w])?";
    var prefixChars = "([\\w" + (excludePeriod ? "." : "") + "])?";
    var regExp = new RegExp(prefixChars + token + suffixChars, "g");
    material.shaderSource = material.shaderSource.replace(regExp, function (
      $0,
      $1,
      $2
    ) {
      if ($1 || $2) {
        return $0;
      }
      count += 1;
      return newToken;
    });
    return count;
  }

  function getNumberOfTokens(material, token, excludePeriod) {
    return replaceToken(material, token, token, excludePeriod);
  }

  Material._materialCache = {
    _materials: {},
    addMaterial: function (type, materialTemplate) {
      this._materials[type] = materialTemplate;
    },
    getMaterial: function (type) {
      return this._materials[type];
    },
  };

  /**
   * Gets or sets the default texture uniform value.
   * @type {String}
   */
  Material.DefaultImageId = "czm_defaultImage";

  /**
   * Gets or sets the default cube map texture uniform value.
   * @type {String}
   */
  Material.DefaultCubeMapId = "czm_defaultCubeMap";

  /**
   * Gets the name of the color material.
   * @type {String}
   * @readonly
   */
  Material.ColorType = "Color";
  Material._materialCache.addMaterial(Material.ColorType, {
    fabric: {
      type: Material.ColorType,
      uniforms: {
        color: new Color(1.0, 0.0, 0.0, 0.5),
      },
      components: {
        diffuse: "color.rgb",
        alpha: "color.a",
      },
    },
    translucent: function (material) {
      return material.uniforms.color.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the image material.
   * @type {String}
   * @readonly
   */
  Material.ImageType = "Image";
  Material._materialCache.addMaterial(Material.ImageType, {
    fabric: {
      type: Material.ImageType,
      uniforms: {
        image: Material.DefaultImageId,
        repeat: new Cartesian2(1.0, 1.0),
        color: new Color(1.0, 1.0, 1.0, 1.0),
      },
      components: {
        diffuse:
          "texture2D(image, fract(repeat * materialInput.st)).rgb * color.rgb",
        alpha: "texture2D(image, fract(repeat * materialInput.st)).a * color.a",
      },
    },
    translucent: function (material) {
      return material.uniforms.color.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the diffuce map material.
   * @type {String}
   * @readonly
   */
  Material.DiffuseMapType = "DiffuseMap";
  Material._materialCache.addMaterial(Material.DiffuseMapType, {
    fabric: {
      type: Material.DiffuseMapType,
      uniforms: {
        image: Material.DefaultImageId,
        channels: "rgb",
        repeat: new Cartesian2(1.0, 1.0),
      },
      components: {
        diffuse: "texture2D(image, fract(repeat * materialInput.st)).channels",
      },
    },
    translucent: false,
  });

  /**
   * Gets the name of the alpha map material.
   * @type {String}
   * @readonly
   */
  Material.AlphaMapType = "AlphaMap";
  Material._materialCache.addMaterial(Material.AlphaMapType, {
    fabric: {
      type: Material.AlphaMapType,
      uniforms: {
        image: Material.DefaultImageId,
        channel: "a",
        repeat: new Cartesian2(1.0, 1.0),
      },
      components: {
        alpha: "texture2D(image, fract(repeat * materialInput.st)).channel",
      },
    },
    translucent: true,
  });

  /**
   * Gets the name of the specular map material.
   * @type {String}
   * @readonly
   */
  Material.SpecularMapType = "SpecularMap";
  Material._materialCache.addMaterial(Material.SpecularMapType, {
    fabric: {
      type: Material.SpecularMapType,
      uniforms: {
        image: Material.DefaultImageId,
        channel: "r",
        repeat: new Cartesian2(1.0, 1.0),
      },
      components: {
        specular: "texture2D(image, fract(repeat * materialInput.st)).channel",
      },
    },
    translucent: false,
  });

  /**
   * Gets the name of the emmision map material.
   * @type {String}
   * @readonly
   */
  Material.EmissionMapType = "EmissionMap";
  Material._materialCache.addMaterial(Material.EmissionMapType, {
    fabric: {
      type: Material.EmissionMapType,
      uniforms: {
        image: Material.DefaultImageId,
        channels: "rgb",
        repeat: new Cartesian2(1.0, 1.0),
      },
      components: {
        emission: "texture2D(image, fract(repeat * materialInput.st)).channels",
      },
    },
    translucent: false,
  });

  /**
   * Gets the name of the bump map material.
   * @type {String}
   * @readonly
   */
  Material.BumpMapType = "BumpMap";
  Material._materialCache.addMaterial(Material.BumpMapType, {
    fabric: {
      type: Material.BumpMapType,
      uniforms: {
        image: Material.DefaultImageId,
        channel: "r",
        strength: 0.8,
        repeat: new Cartesian2(1.0, 1.0),
      },
      source: BumpMapMaterial,
    },
    translucent: false,
  });

  /**
   * Gets the name of the normal map material.
   * @type {String}
   * @readonly
   */
  Material.NormalMapType = "NormalMap";
  Material._materialCache.addMaterial(Material.NormalMapType, {
    fabric: {
      type: Material.NormalMapType,
      uniforms: {
        image: Material.DefaultImageId,
        channels: "rgb",
        strength: 0.8,
        repeat: new Cartesian2(1.0, 1.0),
      },
      source: NormalMapMaterial,
    },
    translucent: false,
  });

  /**
   * Gets the name of the grid material.
   * @type {String}
   * @readonly
   */
  Material.GridType = "Grid";
  Material._materialCache.addMaterial(Material.GridType, {
    fabric: {
      type: Material.GridType,
      uniforms: {
        color: new Color(0.0, 1.0, 0.0, 1.0),
        cellAlpha: 0.1,
        lineCount: new Cartesian2(8.0, 8.0),
        lineThickness: new Cartesian2(1.0, 1.0),
        lineOffset: new Cartesian2(0.0, 0.0),
      },
      source: GridMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return uniforms.color.alpha < 1.0 || uniforms.cellAlpha < 1.0;
    },
  });

  /**
   * Gets the name of the stripe material.
   * @type {String}
   * @readonly
   */
  Material.StripeType = "Stripe";
  Material._materialCache.addMaterial(Material.StripeType, {
    fabric: {
      type: Material.StripeType,
      uniforms: {
        horizontal: true,
        evenColor: new Color(1.0, 1.0, 1.0, 0.5),
        oddColor: new Color(0.0, 0.0, 1.0, 0.5),
        offset: 0.0,
        repeat: 5.0,
      },
      source: StripeMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return uniforms.evenColor.alpha < 1.0 || uniforms.oddColor.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the checkerboard material.
   * @type {String}
   * @readonly
   */
  Material.CheckerboardType = "Checkerboard";
  Material._materialCache.addMaterial(Material.CheckerboardType, {
    fabric: {
      type: Material.CheckerboardType,
      uniforms: {
        lightColor: new Color(1.0, 1.0, 1.0, 0.5),
        darkColor: new Color(0.0, 0.0, 0.0, 0.5),
        repeat: new Cartesian2(5.0, 5.0),
      },
      source: CheckerboardMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return uniforms.lightColor.alpha < 1.0 || uniforms.darkColor.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the dot material.
   * @type {String}
   * @readonly
   */
  Material.DotType = "Dot";
  Material._materialCache.addMaterial(Material.DotType, {
    fabric: {
      type: Material.DotType,
      uniforms: {
        lightColor: new Color(1.0, 1.0, 0.0, 0.75),
        darkColor: new Color(0.0, 1.0, 1.0, 0.75),
        repeat: new Cartesian2(5.0, 5.0),
      },
      source: DotMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return uniforms.lightColor.alpha < 1.0 || uniforms.darkColor.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the water material.
   * @type {String}
   * @readonly
   */
  Material.WaterType = "Water";
  Material._materialCache.addMaterial(Material.WaterType, {
    fabric: {
      type: Material.WaterType,
      uniforms: {
        baseWaterColor: new Color(0.2, 0.3, 0.6, 1.0),
        blendColor: new Color(0.0, 1.0, 0.699, 1.0),
        specularMap: Material.DefaultImageId,
        normalMap: Material.DefaultImageId,
        frequency: 10.0,
        animationSpeed: 0.01,
        amplitude: 1.0,
        specularIntensity: 0.5,
        fadeFactor: 1.0,
      },
      source: WaterMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return (
        uniforms.baseWaterColor.alpha < 1.0 || uniforms.blendColor.alpha < 1.0
      );
    },
  });

  /**
   * Gets the name of the rim lighting material.
   * @type {String}
   * @readonly
   */
  Material.RimLightingType = "RimLighting";
  Material._materialCache.addMaterial(Material.RimLightingType, {
    fabric: {
      type: Material.RimLightingType,
      uniforms: {
        color: new Color(1.0, 0.0, 0.0, 0.7),
        rimColor: new Color(1.0, 1.0, 1.0, 0.4),
        width: 0.3,
      },
      source: RimLightingMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return uniforms.color.alpha < 1.0 || uniforms.rimColor.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the fade material.
   * @type {String}
   * @readonly
   */
  Material.FadeType = "Fade";
  Material._materialCache.addMaterial(Material.FadeType, {
    fabric: {
      type: Material.FadeType,
      uniforms: {
        fadeInColor: new Color(1.0, 0.0, 0.0, 1.0),
        fadeOutColor: new Color(0.0, 0.0, 0.0, 0.0),
        maximumDistance: 0.5,
        repeat: true,
        fadeDirection: {
          x: true,
          y: true,
        },
        time: new Cartesian2(0.5, 0.5),
      },
      source: FadeMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return (
        uniforms.fadeInColor.alpha < 1.0 || uniforms.fadeOutColor.alpha < 1.0
      );
    },
  });

  /**
   * Gets the name of the polyline arrow material.
   * @type {String}
   * @readonly
   */
  Material.PolylineArrowType = "PolylineArrow";
  Material._materialCache.addMaterial(Material.PolylineArrowType, {
    fabric: {
      type: Material.PolylineArrowType,
      uniforms: {
        color: new Color(1.0, 1.0, 1.0, 1.0),
      },
      source: PolylineArrowMaterial,
    },
    translucent: true,
  });

  /**
   * Gets the name of the polyline glow material.
   * @type {String}
   * @readonly
   */
  Material.PolylineDashType = "PolylineDash";
  Material._materialCache.addMaterial(Material.PolylineDashType, {
    fabric: {
      type: Material.PolylineDashType,
      uniforms: {
        color: new Color(1.0, 0.0, 1.0, 1.0),
        gapColor: new Color(0.0, 0.0, 0.0, 0.0),
        dashLength: 16.0,
        dashPattern: 255.0,
      },
      source: PolylineDashMaterial,
    },
    translucent: true,
  });

  /**
   * Gets the name of the polyline glow material.
   * @type {String}
   * @readonly
   */
  Material.PolylineGlowType = "PolylineGlow";
  Material._materialCache.addMaterial(Material.PolylineGlowType, {
    fabric: {
      type: Material.PolylineGlowType,
      uniforms: {
        color: new Color(0.0, 0.5, 1.0, 1.0),
        glowPower: 0.25,
        taperPower: 1.0,
      },
      source: PolylineGlowMaterial,
    },
    translucent: true,
  });

  /**
   * Gets the name of the polyline outline material.
   * @type {String}
   * @readonly
   */
  Material.PolylineOutlineType = "PolylineOutline";
  Material._materialCache.addMaterial(Material.PolylineOutlineType, {
    fabric: {
      type: Material.PolylineOutlineType,
      uniforms: {
        color: new Color(1.0, 1.0, 1.0, 1.0),
        outlineColor: new Color(1.0, 0.0, 0.0, 1.0),
        outlineWidth: 1.0,
      },
      source: PolylineOutlineMaterial,
    },
    translucent: function (material) {
      var uniforms = material.uniforms;
      return uniforms.color.alpha < 1.0 || uniforms.outlineColor.alpha < 1.0;
    },
  });

  /**
   * Gets the name of the elevation contour material.
   * @type {String}
   * @readonly
   */
  Material.ElevationContourType = "ElevationContour";
  Material._materialCache.addMaterial(Material.ElevationContourType, {
    fabric: {
      type: Material.ElevationContourType,
      uniforms: {
        spacing: 100.0,
        color: new Color(1.0, 0.0, 0.0, 1.0),
        width: 1.0,
      },
      source: ElevationContourMaterial,
    },
    translucent: false,
  });

  /**
   * Gets the name of the elevation contour material.
   * @type {String}
   * @readonly
   */
  Material.ElevationRampType = "ElevationRamp";
  Material._materialCache.addMaterial(Material.ElevationRampType, {
    fabric: {
      type: Material.ElevationRampType,
      uniforms: {
        image: Material.DefaultImageId,
        minimumHeight: 0.0,
        maximumHeight: 10000.0,
      },
      source: ElevationRampMaterial,
    },
    translucent: false,
  });

  /**
   * Gets the name of the slope ramp material.
   * @type {String}
   * @readonly
   */
  Material.SlopeRampMaterialType = "SlopeRamp";
  Material._materialCache.addMaterial(Material.SlopeRampMaterialType, {
    fabric: {
      type: Material.SlopeRampMaterialType,
      uniforms: {
        image: Material.DefaultImageId,
      },
      source: SlopeRampMaterial,
    },
    translucent: false,
  });

  /**
   * Gets the name of the aspect ramp material.
   * @type {String}
   * @readonly
   */
  Material.AspectRampMaterialType = "AspectRamp";
  Material._materialCache.addMaterial(Material.AspectRampMaterialType, {
    fabric: {
      type: Material.AspectRampMaterialType,
      uniforms: {
        image: Material.DefaultImageId,
      },
      source: AspectRampMaterial,
    },
    translucent: false,
  });

  /**
       * An appearance for arbitrary geometry (as opposed to {@link EllipsoidSurfaceAppearance}, for example)
       * that supports shading with materials.
       *
       * @alias MaterialAppearance
       * @constructor
       *
       * @param {Object} [options] Object with the following properties:
       * @param {Boolean} [options.flat=false] When <code>true</code>, flat shading is used in the fragment shader, which means lighting is not taking into account.
       * @param {Boolean} [options.faceForward=!options.closed] When <code>true</code>, the fragment shader flips the surface normal as needed to ensure that the normal faces the viewer to avoid dark spots.  This is useful when both sides of a geometry should be shaded like {@link WallGeometry}.
       * @param {Boolean} [options.translucent=true] When <code>true</code>, the geometry is expected to appear translucent so {@link MaterialAppearance#renderState} has alpha blending enabled.
       * @param {Boolean} [options.closed=false] When <code>true</code>, the geometry is expected to be closed so {@link MaterialAppearance#renderState} has backface culling enabled.
       * @param {MaterialAppearance.MaterialSupportType} [options.materialSupport=MaterialAppearance.MaterialSupport.TEXTURED] The type of materials that will be supported.
       * @param {Material} [options.material=Material.ColorType] The material used to determine the fragment color.
       * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
       * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
       * @param {Object} [options.renderState] Optional render state to override the default render state.
       *
       * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
       * @demo {@link https://sandcastle.cesium.com/index.html?src=Materials.html|Cesium Sandcastle Material Appearance Demo}
       *
       * @example
       * var primitive = new Cesium.Primitive({
       *   geometryInstances : new Cesium.GeometryInstance({
       *     geometry : new Cesium.WallGeometry({
              materialSupport :  Cesium.MaterialAppearance.MaterialSupport.BASIC.vertexFormat,
       *       // ...
       *     })
       *   }),
       *   appearance : new Cesium.MaterialAppearance({
       *     material : Cesium.Material.fromType('Color'),
       *     faceForward : true
       *   })
       *
       * });
       */
  function MaterialAppearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var translucent = defaultValue(options.translucent, true);
    var closed = defaultValue(options.closed, false);
    var materialSupport = defaultValue(
      options.materialSupport,
      MaterialAppearance.MaterialSupport.TEXTURED
    );

    /**
     * The material used to determine the fragment color.  Unlike other {@link MaterialAppearance}
     * properties, this is not read-only, so an appearance's material can change on the fly.
     *
     * @type Material
     *
     * @default {@link Material.ColorType}
     *
     * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
     */
    this.material = defined(options.material)
      ? options.material
      : Material.fromType(Material.ColorType);

    /**
     * When <code>true</code>, the geometry is expected to appear translucent.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.translucent = translucent;

    this._vertexShaderSource = defaultValue(
      options.vertexShaderSource,
      materialSupport.vertexShaderSource
    );
    this._fragmentShaderSource = defaultValue(
      options.fragmentShaderSource,
      materialSupport.fragmentShaderSource
    );
    this._renderState = Appearance.getDefaultRenderState(
      translucent,
      closed,
      options.renderState
    );
    this._closed = closed;

    // Non-derived members

    this._materialSupport = materialSupport;
    this._vertexFormat = materialSupport.vertexFormat;
    this._flat = defaultValue(options.flat, false);
    this._faceForward = defaultValue(options.faceForward, !closed);
  }

  Object.defineProperties(MaterialAppearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },

    /**
     * The GLSL source code for the fragment shader.  The full fragment shader
     * source is built procedurally taking into account {@link MaterialAppearance#material},
     * {@link MaterialAppearance#flat}, and {@link MaterialAppearance#faceForward}.
     * Use {@link MaterialAppearance#getFragmentShaderSource} to get the full source.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     * <p>
     * The render state can be explicitly defined when constructing a {@link MaterialAppearance}
     * instance, or it is set implicitly via {@link MaterialAppearance#translucent}
     * and {@link MaterialAppearance#closed}.
     * </p>
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed so
     * {@link MaterialAppearance#renderState} has backface culling enabled.
     * If the viewer enters the geometry, it will not be visible.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },

    /**
     * The type of materials supported by this instance.  This impacts the required
     * {@link VertexFormat} and the complexity of the vertex and fragment shaders.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {MaterialAppearance.MaterialSupportType}
     * @readonly
     *
     * @default {@link MaterialAppearance.MaterialSupport.TEXTURED}
     */
    materialSupport: {
      get: function () {
        return this._materialSupport;
      },
    },

    /**
     * The {@link VertexFormat} that this appearance instance is compatible with.
     * A geometry can have more vertex attributes and still be compatible - at a
     * potential performance cost - but it can't have less.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type VertexFormat
     * @readonly
     *
     * @default {@link MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat}
     */
    vertexFormat: {
      get: function () {
        return this._vertexFormat;
      },
    },

    /**
     * When <code>true</code>, flat shading is used in the fragment shader,
     * which means lighting is not taking into account.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    flat: {
      get: function () {
        return this._flat;
      },
    },

    /**
     * When <code>true</code>, the fragment shader flips the surface normal
     * as needed to ensure that the normal faces the viewer to avoid
     * dark spots.  This is useful when both sides of a geometry should be
     * shaded like {@link WallGeometry}.
     *
     * @memberof MaterialAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    faceForward: {
      get: function () {
        return this._faceForward;
      },
    },
  });

  /**
   * Procedurally creates the full GLSL fragment shader source.  For {@link MaterialAppearance},
   * this is derived from {@link MaterialAppearance#fragmentShaderSource}, {@link MaterialAppearance#material},
   * {@link MaterialAppearance#flat}, and {@link MaterialAppearance#faceForward}.
   *
   * @function
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  MaterialAppearance.prototype.getFragmentShaderSource =
    Appearance.prototype.getFragmentShaderSource;

  /**
   * Determines if the geometry is translucent based on {@link MaterialAppearance#translucent} and {@link Material#isTranslucent}.
   *
   * @function
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  MaterialAppearance.prototype.isTranslucent = Appearance.prototype.isTranslucent;

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @function
   *
   * @returns {Object} The render state.
   */
  MaterialAppearance.prototype.getRenderState =
    Appearance.prototype.getRenderState;

  /**
   * @typedef MaterialAppearance.MaterialSupportType
   * @type {Object}
   * @property {VertexFormat} vertexFormat
   * @property {String} vertexShaderSource
   * @property {String} fragmentShaderSource
   */

  /**
   * Determines the type of {@link Material} that is supported by a
   * {@link MaterialAppearance} instance.  This is a trade-off between
   * flexibility (a wide array of materials) and memory/performance
   * (required vertex format and GLSL shader complexity.
   * @namespace
   */
  MaterialAppearance.MaterialSupport = {
    /**
     * Only basic materials, which require just <code>position</code> and
     * <code>normal</code> vertex attributes, are supported.
     *
     * @type {MaterialAppearance.MaterialSupportType}
     * @constant
     */
    BASIC: Object.freeze({
      vertexFormat: VertexFormat.POSITION_AND_NORMAL,
      vertexShaderSource: BasicMaterialAppearanceVS,
      fragmentShaderSource: BasicMaterialAppearanceFS,
    }),
    /**
     * Materials with textures, which require <code>position</code>,
     * <code>normal</code>, and <code>st</code> vertex attributes,
     * are supported.  The vast majority of materials fall into this category.
     *
     * @type {MaterialAppearance.MaterialSupportType}
     * @constant
     */
    TEXTURED: Object.freeze({
      vertexFormat: VertexFormat.POSITION_NORMAL_AND_ST,
      vertexShaderSource: TexturedMaterialAppearanceVS,
      fragmentShaderSource: TexturedMaterialAppearanceFS,
    }),
    /**
     * All materials, including those that work in tangent space, are supported.
     * This requires <code>position</code>, <code>normal</code>, <code>st</code>,
     * <code>tangent</code>, and <code>bitangent</code> vertex attributes.
     *
     * @type {MaterialAppearance.MaterialSupportType}
     * @constant
     */
    ALL: Object.freeze({
      vertexFormat: VertexFormat.ALL,
      vertexShaderSource: AllMaterialAppearanceVS,
      fragmentShaderSource: AllMaterialAppearanceFS,
    }),
  };

  //This file is automatically rebuilt by the Cesium build process.
  var PerInstanceColorAppearanceFS = "varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
varying vec4 v_color;\n\
void main()\n\
{\n\
vec3 positionToEyeEC = -v_positionEC;\n\
vec3 normalEC = normalize(v_normalEC);\n\
#ifdef FACE_FORWARD\n\
normalEC = faceforward(normalEC, vec3(0.0, 0.0, 1.0), -normalEC);\n\
#endif\n\
vec4 color = czm_gammaCorrect(v_color);\n\
czm_materialInput materialInput;\n\
materialInput.normalEC = normalEC;\n\
materialInput.positionToEyeEC = positionToEyeEC;\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
material.diffuse = color.rgb;\n\
material.alpha = color.a;\n\
gl_FragColor = czm_phong(normalize(positionToEyeEC), material, czm_lightDirectionEC);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PerInstanceColorAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 normal;\n\
attribute vec4 color;\n\
attribute float batchId;\n\
varying vec3 v_positionEC;\n\
varying vec3 v_normalEC;\n\
varying vec4 v_color;\n\
void main()\n\
{\n\
vec4 p = czm_computePosition();\n\
v_positionEC = (czm_modelViewRelativeToEye * p).xyz;\n\
v_normalEC = czm_normal * normal;\n\
v_color = color;\n\
gl_Position = czm_modelViewProjectionRelativeToEye * p;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PerInstanceFlatColorAppearanceFS = "varying vec4 v_color;\n\
void main()\n\
{\n\
gl_FragColor = czm_gammaCorrect(v_color);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PerInstanceFlatColorAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec4 color;\n\
attribute float batchId;\n\
varying vec4 v_color;\n\
void main()\n\
{\n\
vec4 p = czm_computePosition();\n\
v_color = color;\n\
gl_Position = czm_modelViewProjectionRelativeToEye * p;\n\
}\n\
";

  /**
   * An appearance for {@link GeometryInstance} instances with color attributes.
   * This allows several geometry instances, each with a different color, to
   * be drawn with the same {@link Primitive} as shown in the second example below.
   *
   * @alias PerInstanceColorAppearance
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.flat=false] When <code>true</code>, flat shading is used in the fragment shader, which means lighting is not taking into account.
   * @param {Boolean} [options.faceForward=!options.closed] When <code>true</code>, the fragment shader flips the surface normal as needed to ensure that the normal faces the viewer to avoid dark spots.  This is useful when both sides of a geometry should be shaded like {@link WallGeometry}.
   * @param {Boolean} [options.translucent=true] When <code>true</code>, the geometry is expected to appear translucent so {@link PerInstanceColorAppearance#renderState} has alpha blending enabled.
   * @param {Boolean} [options.closed=false] When <code>true</code>, the geometry is expected to be closed so {@link PerInstanceColorAppearance#renderState} has backface culling enabled.
   * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
   * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
   * @param {Object} [options.renderState] Optional render state to override the default render state.
   *
   * @example
   * // A solid white line segment
   * var primitive = new Cesium.Primitive({
   *   geometryInstances : new Cesium.GeometryInstance({
   *     geometry : new Cesium.SimplePolylineGeometry({
   *       positions : Cesium.Cartesian3.fromDegreesArray([
   *         0.0, 0.0,
   *         5.0, 0.0
   *       ])
   *     }),
   *     attributes : {
   *       color : Cesium.ColorGeometryInstanceAttribute.fromColor(new Cesium.Color(1.0, 1.0, 1.0, 1.0))
   *     }
   *   }),
   *   appearance : new Cesium.PerInstanceColorAppearance({
   *     flat : true,
   *     translucent : false
   *   })
   * });
   *
   * // Two rectangles in a primitive, each with a different color
   * var instance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.RectangleGeometry({
   *     rectangle : Cesium.Rectangle.fromDegrees(0.0, 20.0, 10.0, 30.0)
   *   }),
   *   attributes : {
   *     color : new Cesium.ColorGeometryInstanceAttribute(1.0, 0.0, 0.0, 0.5)
   *   }
   * });
   *
   * var anotherInstance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.RectangleGeometry({
   *     rectangle : Cesium.Rectangle.fromDegrees(0.0, 40.0, 10.0, 50.0)
   *   }),
   *   attributes : {
   *     color : new Cesium.ColorGeometryInstanceAttribute(0.0, 0.0, 1.0, 0.5)
   *   }
   * });
   *
   * var rectanglePrimitive = new Cesium.Primitive({
   *   geometryInstances : [instance, anotherInstance],
   *   appearance : new Cesium.PerInstanceColorAppearance()
   * });
   */
  function PerInstanceColorAppearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var translucent = defaultValue(options.translucent, true);
    var closed = defaultValue(options.closed, false);
    var flat = defaultValue(options.flat, false);
    var vs = flat
      ? PerInstanceFlatColorAppearanceVS
      : PerInstanceColorAppearanceVS;
    var fs = flat
      ? PerInstanceFlatColorAppearanceFS
      : PerInstanceColorAppearanceFS;
    var vertexFormat = flat
      ? PerInstanceColorAppearance.FLAT_VERTEX_FORMAT
      : PerInstanceColorAppearance.VERTEX_FORMAT;

    /**
     * This property is part of the {@link Appearance} interface, but is not
     * used by {@link PerInstanceColorAppearance} since a fully custom fragment shader is used.
     *
     * @type Material
     *
     * @default undefined
     */
    this.material = undefined;

    /**
     * When <code>true</code>, the geometry is expected to appear translucent so
     * {@link PerInstanceColorAppearance#renderState} has alpha blending enabled.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.translucent = translucent;

    this._vertexShaderSource = defaultValue(options.vertexShaderSource, vs);
    this._fragmentShaderSource = defaultValue(options.fragmentShaderSource, fs);
    this._renderState = Appearance.getDefaultRenderState(
      translucent,
      closed,
      options.renderState
    );
    this._closed = closed;

    // Non-derived members

    this._vertexFormat = vertexFormat;
    this._flat = flat;
    this._faceForward = defaultValue(options.faceForward, !closed);
  }

  Object.defineProperties(PerInstanceColorAppearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },

    /**
     * The GLSL source code for the fragment shader.
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     * <p>
     * The render state can be explicitly defined when constructing a {@link PerInstanceColorAppearance}
     * instance, or it is set implicitly via {@link PerInstanceColorAppearance#translucent}
     * and {@link PerInstanceColorAppearance#closed}.
     * </p>
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed so
     * {@link PerInstanceColorAppearance#renderState} has backface culling enabled.
     * If the viewer enters the geometry, it will not be visible.
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },

    /**
     * The {@link VertexFormat} that this appearance instance is compatible with.
     * A geometry can have more vertex attributes and still be compatible - at a
     * potential performance cost - but it can't have less.
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type VertexFormat
     * @readonly
     */
    vertexFormat: {
      get: function () {
        return this._vertexFormat;
      },
    },

    /**
     * When <code>true</code>, flat shading is used in the fragment shader,
     * which means lighting is not taking into account.
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    flat: {
      get: function () {
        return this._flat;
      },
    },

    /**
     * When <code>true</code>, the fragment shader flips the surface normal
     * as needed to ensure that the normal faces the viewer to avoid
     * dark spots.  This is useful when both sides of a geometry should be
     * shaded like {@link WallGeometry}.
     *
     * @memberof PerInstanceColorAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    faceForward: {
      get: function () {
        return this._faceForward;
      },
    },
  });

  /**
   * The {@link VertexFormat} that all {@link PerInstanceColorAppearance} instances
   * are compatible with.  This requires only <code>position</code> and <code>normal</code>
   * attributes.
   *
   * @type VertexFormat
   *
   * @constant
   */
  PerInstanceColorAppearance.VERTEX_FORMAT = VertexFormat.POSITION_AND_NORMAL;

  /**
   * The {@link VertexFormat} that all {@link PerInstanceColorAppearance} instances
   * are compatible with when {@link PerInstanceColorAppearance#flat} is <code>true</code>.
   * This requires only a <code>position</code> attribute.
   *
   * @type VertexFormat
   *
   * @constant
   */
  PerInstanceColorAppearance.FLAT_VERTEX_FORMAT = VertexFormat.POSITION_ONLY;

  /**
   * Procedurally creates the full GLSL fragment shader source.  For {@link PerInstanceColorAppearance},
   * this is derived from {@link PerInstanceColorAppearance#fragmentShaderSource}, {@link PerInstanceColorAppearance#flat},
   * and {@link PerInstanceColorAppearance#faceForward}.
   *
   * @function
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  PerInstanceColorAppearance.prototype.getFragmentShaderSource =
    Appearance.prototype.getFragmentShaderSource;

  /**
   * Determines if the geometry is translucent based on {@link PerInstanceColorAppearance#translucent}.
   *
   * @function
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  PerInstanceColorAppearance.prototype.isTranslucent =
    Appearance.prototype.isTranslucent;

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @function
   *
   * @returns {Object} The render state.
   */
  PerInstanceColorAppearance.prototype.getRenderState =
    Appearance.prototype.getRenderState;

  /**
   * A {@link MaterialProperty} that maps to solid color {@link Material} uniforms.
   *
   * @param {Property|Color} [color=Color.WHITE] The {@link Color} Property to be used.
   *
   * @alias ColorMaterialProperty
   * @constructor
   */
  function ColorMaterialProperty(color) {
    this._definitionChanged = new Event();
    this._color = undefined;
    this._colorSubscription = undefined;

    this.color = color;
  }

  Object.defineProperties(ColorMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof ColorMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return Property.isConstant(this._color);
      },
    },

    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof ColorMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the {@link Color} {@link Property}.
     * @memberof ColorMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  ColorMaterialProperty.prototype.getType = function (time) {
    return "Color";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ColorMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      Color.WHITE,
      result.color
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  ColorMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof ColorMaterialProperty && //
        Property.equals(this._color, other._color))
    );
  };

  /**
   * Represents a command to the renderer for drawing.
   *
   * @private
   */
  function DrawCommand(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._boundingVolume = options.boundingVolume;
    this._orientedBoundingBox = options.orientedBoundingBox;
    this._cull = defaultValue(options.cull, true);
    this._occlude = defaultValue(options.occlude, true);
    this._modelMatrix = options.modelMatrix;
    this._primitiveType = defaultValue(
      options.primitiveType,
      PrimitiveType$1.TRIANGLES
    );
    this._vertexArray = options.vertexArray;
    this._count = options.count;
    this._offset = defaultValue(options.offset, 0);
    this._instanceCount = defaultValue(options.instanceCount, 0);
    this._shaderProgram = options.shaderProgram;
    this._uniformMap = options.uniformMap;
    this._renderState = options.renderState;
    this._framebuffer = options.framebuffer;
    this._pass = options.pass;
    this._executeInClosestFrustum = defaultValue(
      options.executeInClosestFrustum,
      false
    );
    this._owner = options.owner;
    this._debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );
    this._debugOverlappingFrustums = 0;
    this._castShadows = defaultValue(options.castShadows, false);
    this._receiveShadows = defaultValue(options.receiveShadows, false);
    this._pickId = options.pickId;
    this._pickOnly = defaultValue(options.pickOnly, false);

    this.dirty = true;
    this.lastDirtyTime = 0;

    /**
     * @private
     */
    this.derivedCommands = {};
  }

  Object.defineProperties(DrawCommand.prototype, {
    /**
     * The bounding volume of the geometry in world space.  This is used for culling and frustum selection.
     * <p>
     * For best rendering performance, use the tightest possible bounding volume.  Although
     * <code>undefined</code> is allowed, always try to provide a bounding volume to
     * allow the tightest possible near and far planes to be computed for the scene, and
     * minimize the number of frustums needed.
     * </p>
     *
     * @memberof DrawCommand.prototype
     * @type {Object}
     * @default undefined
     *
     * @see DrawCommand#debugShowBoundingVolume
     */
    boundingVolume: {
      get: function () {
        return this._boundingVolume;
      },
      set: function (value) {
        if (this._boundingVolume !== value) {
          this._boundingVolume = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The oriented bounding box of the geometry in world space. If this is defined, it is used instead of
     * {@link DrawCommand#boundingVolume} for plane intersection testing.
     *
     * @memberof DrawCommand.prototype
     * @type {OrientedBoundingBox}
     * @default undefined
     *
     * @see DrawCommand#debugShowBoundingVolume
     */
    orientedBoundingBox: {
      get: function () {
        return this._orientedBoundingBox;
      },
      set: function (value) {
        if (this._orientedBoundingBox !== value) {
          this._orientedBoundingBox = value;
          this.dirty = true;
        }
      },
    },

    /**
     * When <code>true</code>, the renderer frustum and horizon culls the command based on its {@link DrawCommand#boundingVolume}.
     * If the command was already culled, set this to <code>false</code> for a performance improvement.
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default true
     */
    cull: {
      get: function () {
        return this._cull;
      },
      set: function (value) {
        if (this._cull !== value) {
          this._cull = value;
          this.dirty = true;
        }
      },
    },

    /**
     * When <code>true</code>, the horizon culls the command based on its {@link DrawCommand#boundingVolume}.
     * {@link DrawCommand#cull} must also be <code>true</code> in order for the command to be culled.
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default true
     */
    occlude: {
      get: function () {
        return this._occlude;
      },
      set: function (value) {
        if (this._occlude !== value) {
          this._occlude = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The transformation from the geometry in model space to world space.
     * <p>
     * When <code>undefined</code>, the geometry is assumed to be defined in world space.
     * </p>
     *
     * @memberof DrawCommand.prototype
     * @type {Matrix4}
     * @default undefined
     */
    modelMatrix: {
      get: function () {
        return this._modelMatrix;
      },
      set: function (value) {
        if (this._modelMatrix !== value) {
          this._modelMatrix = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The type of geometry in the vertex array.
     *
     * @memberof DrawCommand.prototype
     * @type {PrimitiveType}
     * @default PrimitiveType.TRIANGLES
     */
    primitiveType: {
      get: function () {
        return this._primitiveType;
      },
      set: function (value) {
        if (this._primitiveType !== value) {
          this._primitiveType = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The vertex array.
     *
     * @memberof DrawCommand.prototype
     * @type {VertexArray}
     * @default undefined
     */
    vertexArray: {
      get: function () {
        return this._vertexArray;
      },
      set: function (value) {
        if (this._vertexArray !== value) {
          this._vertexArray = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The number of vertices to draw in the vertex array.
     *
     * @memberof DrawCommand.prototype
     * @type {Number}
     * @default undefined
     */
    count: {
      get: function () {
        return this._count;
      },
      set: function (value) {
        if (this._count !== value) {
          this._count = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The offset to start drawing in the vertex array.
     *
     * @memberof DrawCommand.prototype
     * @type {Number}
     * @default 0
     */
    offset: {
      get: function () {
        return this._offset;
      },
      set: function (value) {
        if (this._offset !== value) {
          this._offset = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The number of instances to draw.
     *
     * @memberof DrawCommand.prototype
     * @type {Number}
     * @default 0
     */
    instanceCount: {
      get: function () {
        return this._instanceCount;
      },
      set: function (value) {
        if (this._instanceCount !== value) {
          this._instanceCount = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The shader program to apply.
     *
     * @memberof DrawCommand.prototype
     * @type {ShaderProgram}
     * @default undefined
     */
    shaderProgram: {
      get: function () {
        return this._shaderProgram;
      },
      set: function (value) {
        if (this._shaderProgram !== value) {
          this._shaderProgram = value;
          this.dirty = true;
        }
      },
    },

    /**
     * Whether this command should cast shadows when shadowing is enabled.
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default false
     */
    castShadows: {
      get: function () {
        return this._castShadows;
      },
      set: function (value) {
        if (this._castShadows !== value) {
          this._castShadows = value;
          this.dirty = true;
        }
      },
    },

    /**
     * Whether this command should receive shadows when shadowing is enabled.
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default false
     */
    receiveShadows: {
      get: function () {
        return this._receiveShadows;
      },
      set: function (value) {
        if (this._receiveShadows !== value) {
          this._receiveShadows = value;
          this.dirty = true;
        }
      },
    },

    /**
     * An object with functions whose names match the uniforms in the shader program
     * and return values to set those uniforms.
     *
     * @memberof DrawCommand.prototype
     * @type {Object}
     * @default undefined
     */
    uniformMap: {
      get: function () {
        return this._uniformMap;
      },
      set: function (value) {
        if (this._uniformMap !== value) {
          this._uniformMap = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The render state.
     *
     * @memberof DrawCommand.prototype
     * @type {RenderState}
     * @default undefined
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
      set: function (value) {
        if (this._renderState !== value) {
          this._renderState = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The framebuffer to draw to.
     *
     * @memberof DrawCommand.prototype
     * @type {Framebuffer}
     * @default undefined
     */
    framebuffer: {
      get: function () {
        return this._framebuffer;
      },
      set: function (value) {
        if (this._framebuffer !== value) {
          this._framebuffer = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The pass when to render.
     *
     * @memberof DrawCommand.prototype
     * @type {Pass}
     * @default undefined
     */
    pass: {
      get: function () {
        return this._pass;
      },
      set: function (value) {
        if (this._pass !== value) {
          this._pass = value;
          this.dirty = true;
        }
      },
    },

    /**
     * Specifies if this command is only to be executed in the frustum closest
     * to the eye containing the bounding volume. Defaults to <code>false</code>.
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default false
     */
    executeInClosestFrustum: {
      get: function () {
        return this._executeInClosestFrustum;
      },
      set: function (value) {
        if (this._executeInClosestFrustum !== value) {
          this._executeInClosestFrustum = value;
          this.dirty = true;
        }
      },
    },

    /**
     * The object who created this command.  This is useful for debugging command
     * execution; it allows us to see who created a command when we only have a
     * reference to the command, and can be used to selectively execute commands
     * with {@link Scene#debugCommandFilter}.
     *
     * @memberof DrawCommand.prototype
     * @type {Object}
     * @default undefined
     *
     * @see Scene#debugCommandFilter
     */
    owner: {
      get: function () {
        return this._owner;
      },
      set: function (value) {
        if (this._owner !== value) {
          this._owner = value;
          this.dirty = true;
        }
      },
    },

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the {@link DrawCommand#boundingVolume} for this command, assuming it is a sphere, when the command executes.
     * </p>
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default false
     *
     * @see DrawCommand#boundingVolume
     */
    debugShowBoundingVolume: {
      get: function () {
        return this._debugShowBoundingVolume;
      },
      set: function (value) {
        if (this._debugShowBoundingVolume !== value) {
          this._debugShowBoundingVolume = value;
          this.dirty = true;
        }
      },
    },

    /**
     * Used to implement Scene.debugShowFrustums.
     * @private
     */
    debugOverlappingFrustums: {
      get: function () {
        return this._debugOverlappingFrustums;
      },
      set: function (value) {
        if (this._debugOverlappingFrustums !== value) {
          this._debugOverlappingFrustums = value;
          this.dirty = true;
        }
      },
    },
    /**
     * A GLSL string that will evaluate to a pick id. When <code>undefined</code>, the command will only draw depth
     * during the pick pass.
     *
     * @memberof DrawCommand.prototype
     * @type {String}
     * @default undefined
     */
    pickId: {
      get: function () {
        return this._pickId;
      },
      set: function (value) {
        if (this._pickId !== value) {
          this._pickId = value;
          this.dirty = true;
        }
      },
    },
    /**
     * Whether this command should be executed in the pick pass only.
     *
     * @memberof DrawCommand.prototype
     * @type {Boolean}
     * @default false
     */
    pickOnly: {
      get: function () {
        return this._pickOnly;
      },
      set: function (value) {
        if (this._pickOnly !== value) {
          this._pickOnly = value;
          this.dirty = true;
        }
      },
    },
  });

  /**
   * @private
   */
  DrawCommand.shallowClone = function (command, result) {
    if (!defined(command)) {
      return undefined;
    }
    if (!defined(result)) {
      result = new DrawCommand();
    }

    result._boundingVolume = command._boundingVolume;
    result._orientedBoundingBox = command._orientedBoundingBox;
    result._cull = command._cull;
    result._occlude = command._occlude;
    result._modelMatrix = command._modelMatrix;
    result._primitiveType = command._primitiveType;
    result._vertexArray = command._vertexArray;
    result._count = command._count;
    result._offset = command._offset;
    result._instanceCount = command._instanceCount;
    result._shaderProgram = command._shaderProgram;
    result._uniformMap = command._uniformMap;
    result._renderState = command._renderState;
    result._framebuffer = command._framebuffer;
    result._pass = command._pass;
    result._executeInClosestFrustum = command._executeInClosestFrustum;
    result._owner = command._owner;
    result._debugShowBoundingVolume = command._debugShowBoundingVolume;
    result._debugOverlappingFrustums = command._debugOverlappingFrustums;
    result._castShadows = command._castShadows;
    result._receiveShadows = command._receiveShadows;
    result._pickId = command._pickId;
    result._pickOnly = command._pickOnly;

    result.dirty = true;
    result.lastDirtyTime = 0;

    return result;
  };

  /**
   * Executes the draw command.
   *
   * @param {Context} context The renderer context in which to draw.
   * @param {PassState} [passState] The state for the current render pass.
   */
  DrawCommand.prototype.execute = function (context, passState) {
    context.draw(this, passState);
  };

  /**
   * The render pass for a command.
   *
   * @private
   */
  var Pass = {
    // If you add/modify/remove Pass constants, also change the automatic GLSL constants
    // that start with 'czm_pass'
    //
    // Commands are executed in order by pass up to the translucent pass.
    // Translucent geometry needs special handling (sorting/OIT). The compute pass
    // is executed first and the overlay pass is executed last. Both are not sorted
    // by frustum.
    ENVIRONMENT: 0,
    COMPUTE: 1,
    GLOBE: 2,
    TERRAIN_CLASSIFICATION: 3,
    CESIUM_3D_TILE: 4,
    CESIUM_3D_TILE_CLASSIFICATION: 5,
    CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW: 6,
    OPAQUE: 7,
    TRANSLUCENT: 8,
    OVERLAY: 9,
    NUMBER_OF_PASSES: 10,
  };
  var Pass$1 = Object.freeze(Pass);

  /**
   * Returns frozen renderState as well as all of the object literal properties. This function is deep object freeze
   * function ignoring properties named "_applyFunctions".
   *
   * @private
   *
   * @param {Object} renderState
   * @returns {Object} Returns frozen renderState.
   *
   */
  function freezeRenderState(renderState) {
    if (typeof renderState !== "object" || renderState === null) {
      return renderState;
    }

    var propName;
    var propNames = Object.keys(renderState);

    for (var i = 0; i < propNames.length; i++) {
      propName = propNames[i];
      if (
        renderState.hasOwnProperty(propName) &&
        propName !== "_applyFunctions"
      ) {
        renderState[propName] = freezeRenderState(renderState[propName]);
      }
    }
    return Object.freeze(renderState);
  }

  function validateBlendEquation(blendEquation) {
    return (
      blendEquation === WebGLConstants$1.FUNC_ADD ||
      blendEquation === WebGLConstants$1.FUNC_SUBTRACT ||
      blendEquation === WebGLConstants$1.FUNC_REVERSE_SUBTRACT ||
      blendEquation === WebGLConstants$1.MIN ||
      blendEquation === WebGLConstants$1.MAX
    );
  }

  function validateBlendFunction(blendFunction) {
    return (
      blendFunction === WebGLConstants$1.ZERO ||
      blendFunction === WebGLConstants$1.ONE ||
      blendFunction === WebGLConstants$1.SRC_COLOR ||
      blendFunction === WebGLConstants$1.ONE_MINUS_SRC_COLOR ||
      blendFunction === WebGLConstants$1.DST_COLOR ||
      blendFunction === WebGLConstants$1.ONE_MINUS_DST_COLOR ||
      blendFunction === WebGLConstants$1.SRC_ALPHA ||
      blendFunction === WebGLConstants$1.ONE_MINUS_SRC_ALPHA ||
      blendFunction === WebGLConstants$1.DST_ALPHA ||
      blendFunction === WebGLConstants$1.ONE_MINUS_DST_ALPHA ||
      blendFunction === WebGLConstants$1.CONSTANT_COLOR ||
      blendFunction === WebGLConstants$1.ONE_MINUS_CONSTANT_COLOR ||
      blendFunction === WebGLConstants$1.CONSTANT_ALPHA ||
      blendFunction === WebGLConstants$1.ONE_MINUS_CONSTANT_ALPHA ||
      blendFunction === WebGLConstants$1.SRC_ALPHA_SATURATE
    );
  }

  function validateCullFace(cullFace) {
    return (
      cullFace === WebGLConstants$1.FRONT ||
      cullFace === WebGLConstants$1.BACK ||
      cullFace === WebGLConstants$1.FRONT_AND_BACK
    );
  }

  function validateDepthFunction(depthFunction) {
    return (
      depthFunction === WebGLConstants$1.NEVER ||
      depthFunction === WebGLConstants$1.LESS ||
      depthFunction === WebGLConstants$1.EQUAL ||
      depthFunction === WebGLConstants$1.LEQUAL ||
      depthFunction === WebGLConstants$1.GREATER ||
      depthFunction === WebGLConstants$1.NOTEQUAL ||
      depthFunction === WebGLConstants$1.GEQUAL ||
      depthFunction === WebGLConstants$1.ALWAYS
    );
  }

  function validateStencilFunction(stencilFunction) {
    return (
      stencilFunction === WebGLConstants$1.NEVER ||
      stencilFunction === WebGLConstants$1.LESS ||
      stencilFunction === WebGLConstants$1.EQUAL ||
      stencilFunction === WebGLConstants$1.LEQUAL ||
      stencilFunction === WebGLConstants$1.GREATER ||
      stencilFunction === WebGLConstants$1.NOTEQUAL ||
      stencilFunction === WebGLConstants$1.GEQUAL ||
      stencilFunction === WebGLConstants$1.ALWAYS
    );
  }

  function validateStencilOperation(stencilOperation) {
    return (
      stencilOperation === WebGLConstants$1.ZERO ||
      stencilOperation === WebGLConstants$1.KEEP ||
      stencilOperation === WebGLConstants$1.REPLACE ||
      stencilOperation === WebGLConstants$1.INCR ||
      stencilOperation === WebGLConstants$1.DECR ||
      stencilOperation === WebGLConstants$1.INVERT ||
      stencilOperation === WebGLConstants$1.INCR_WRAP ||
      stencilOperation === WebGLConstants$1.DECR_WRAP
    );
  }

  /**
   * @private
   */
  function RenderState(renderState) {
    var rs = defaultValue(renderState, defaultValue.EMPTY_OBJECT);
    var cull = defaultValue(rs.cull, defaultValue.EMPTY_OBJECT);
    var polygonOffset = defaultValue(rs.polygonOffset, defaultValue.EMPTY_OBJECT);
    var scissorTest = defaultValue(rs.scissorTest, defaultValue.EMPTY_OBJECT);
    var scissorTestRectangle = defaultValue(
      scissorTest.rectangle,
      defaultValue.EMPTY_OBJECT
    );
    var depthRange = defaultValue(rs.depthRange, defaultValue.EMPTY_OBJECT);
    var depthTest = defaultValue(rs.depthTest, defaultValue.EMPTY_OBJECT);
    var colorMask = defaultValue(rs.colorMask, defaultValue.EMPTY_OBJECT);
    var blending = defaultValue(rs.blending, defaultValue.EMPTY_OBJECT);
    var blendingColor = defaultValue(blending.color, defaultValue.EMPTY_OBJECT);
    var stencilTest = defaultValue(rs.stencilTest, defaultValue.EMPTY_OBJECT);
    var stencilTestFrontOperation = defaultValue(
      stencilTest.frontOperation,
      defaultValue.EMPTY_OBJECT
    );
    var stencilTestBackOperation = defaultValue(
      stencilTest.backOperation,
      defaultValue.EMPTY_OBJECT
    );
    var sampleCoverage = defaultValue(
      rs.sampleCoverage,
      defaultValue.EMPTY_OBJECT
    );
    var viewport = rs.viewport;

    this.frontFace = defaultValue(rs.frontFace, WindingOrder$1.COUNTER_CLOCKWISE);
    this.cull = {
      enabled: defaultValue(cull.enabled, false),
      face: defaultValue(cull.face, WebGLConstants$1.BACK),
    };
    this.lineWidth = defaultValue(rs.lineWidth, 1.0);
    this.polygonOffset = {
      enabled: defaultValue(polygonOffset.enabled, false),
      factor: defaultValue(polygonOffset.factor, 0),
      units: defaultValue(polygonOffset.units, 0),
    };
    this.scissorTest = {
      enabled: defaultValue(scissorTest.enabled, false),
      rectangle: BoundingRectangle.clone(scissorTestRectangle),
    };
    this.depthRange = {
      near: defaultValue(depthRange.near, 0),
      far: defaultValue(depthRange.far, 1),
    };
    this.depthTest = {
      enabled: defaultValue(depthTest.enabled, false),
      func: defaultValue(depthTest.func, WebGLConstants$1.LESS), // func, because function is a JavaScript keyword
    };
    this.colorMask = {
      red: defaultValue(colorMask.red, true),
      green: defaultValue(colorMask.green, true),
      blue: defaultValue(colorMask.blue, true),
      alpha: defaultValue(colorMask.alpha, true),
    };
    this.depthMask = defaultValue(rs.depthMask, true);
    this.stencilMask = defaultValue(rs.stencilMask, ~0);
    this.blending = {
      enabled: defaultValue(blending.enabled, false),
      color: new Color(
        defaultValue(blendingColor.red, 0.0),
        defaultValue(blendingColor.green, 0.0),
        defaultValue(blendingColor.blue, 0.0),
        defaultValue(blendingColor.alpha, 0.0)
      ),
      equationRgb: defaultValue(blending.equationRgb, WebGLConstants$1.FUNC_ADD),
      equationAlpha: defaultValue(
        blending.equationAlpha,
        WebGLConstants$1.FUNC_ADD
      ),
      functionSourceRgb: defaultValue(
        blending.functionSourceRgb,
        WebGLConstants$1.ONE
      ),
      functionSourceAlpha: defaultValue(
        blending.functionSourceAlpha,
        WebGLConstants$1.ONE
      ),
      functionDestinationRgb: defaultValue(
        blending.functionDestinationRgb,
        WebGLConstants$1.ZERO
      ),
      functionDestinationAlpha: defaultValue(
        blending.functionDestinationAlpha,
        WebGLConstants$1.ZERO
      ),
    };
    this.stencilTest = {
      enabled: defaultValue(stencilTest.enabled, false),
      frontFunction: defaultValue(
        stencilTest.frontFunction,
        WebGLConstants$1.ALWAYS
      ),
      backFunction: defaultValue(stencilTest.backFunction, WebGLConstants$1.ALWAYS),
      reference: defaultValue(stencilTest.reference, 0),
      mask: defaultValue(stencilTest.mask, ~0),
      frontOperation: {
        fail: defaultValue(stencilTestFrontOperation.fail, WebGLConstants$1.KEEP),
        zFail: defaultValue(stencilTestFrontOperation.zFail, WebGLConstants$1.KEEP),
        zPass: defaultValue(stencilTestFrontOperation.zPass, WebGLConstants$1.KEEP),
      },
      backOperation: {
        fail: defaultValue(stencilTestBackOperation.fail, WebGLConstants$1.KEEP),
        zFail: defaultValue(stencilTestBackOperation.zFail, WebGLConstants$1.KEEP),
        zPass: defaultValue(stencilTestBackOperation.zPass, WebGLConstants$1.KEEP),
      },
    };
    this.sampleCoverage = {
      enabled: defaultValue(sampleCoverage.enabled, false),
      value: defaultValue(sampleCoverage.value, 1.0),
      invert: defaultValue(sampleCoverage.invert, false),
    };
    this.viewport = defined(viewport)
      ? new BoundingRectangle(
          viewport.x,
          viewport.y,
          viewport.width,
          viewport.height
        )
      : undefined;

    //>>includeStart('debug', pragmas.debug);
    if (
      this.lineWidth < ContextLimits.minimumAliasedLineWidth ||
      this.lineWidth > ContextLimits.maximumAliasedLineWidth
    ) {
      throw new DeveloperError(
        "renderState.lineWidth is out of range.  Check minimumAliasedLineWidth and maximumAliasedLineWidth."
      );
    }
    if (!WindingOrder$1.validate(this.frontFace)) {
      throw new DeveloperError("Invalid renderState.frontFace.");
    }
    if (!validateCullFace(this.cull.face)) {
      throw new DeveloperError("Invalid renderState.cull.face.");
    }
    if (
      this.scissorTest.rectangle.width < 0 ||
      this.scissorTest.rectangle.height < 0
    ) {
      throw new DeveloperError(
        "renderState.scissorTest.rectangle.width and renderState.scissorTest.rectangle.height must be greater than or equal to zero."
      );
    }
    if (this.depthRange.near > this.depthRange.far) {
      // WebGL specific - not an error in GL ES
      throw new DeveloperError(
        "renderState.depthRange.near can not be greater than renderState.depthRange.far."
      );
    }
    if (this.depthRange.near < 0) {
      // Would be clamped by GL
      throw new DeveloperError(
        "renderState.depthRange.near must be greater than or equal to zero."
      );
    }
    if (this.depthRange.far > 1) {
      // Would be clamped by GL
      throw new DeveloperError(
        "renderState.depthRange.far must be less than or equal to one."
      );
    }
    if (!validateDepthFunction(this.depthTest.func)) {
      throw new DeveloperError("Invalid renderState.depthTest.func.");
    }
    if (
      this.blending.color.red < 0.0 ||
      this.blending.color.red > 1.0 ||
      this.blending.color.green < 0.0 ||
      this.blending.color.green > 1.0 ||
      this.blending.color.blue < 0.0 ||
      this.blending.color.blue > 1.0 ||
      this.blending.color.alpha < 0.0 ||
      this.blending.color.alpha > 1.0
    ) {
      // Would be clamped by GL
      throw new DeveloperError(
        "renderState.blending.color components must be greater than or equal to zero and less than or equal to one."
      );
    }
    if (!validateBlendEquation(this.blending.equationRgb)) {
      throw new DeveloperError("Invalid renderState.blending.equationRgb.");
    }
    if (!validateBlendEquation(this.blending.equationAlpha)) {
      throw new DeveloperError("Invalid renderState.blending.equationAlpha.");
    }
    if (!validateBlendFunction(this.blending.functionSourceRgb)) {
      throw new DeveloperError("Invalid renderState.blending.functionSourceRgb.");
    }
    if (!validateBlendFunction(this.blending.functionSourceAlpha)) {
      throw new DeveloperError(
        "Invalid renderState.blending.functionSourceAlpha."
      );
    }
    if (!validateBlendFunction(this.blending.functionDestinationRgb)) {
      throw new DeveloperError(
        "Invalid renderState.blending.functionDestinationRgb."
      );
    }
    if (!validateBlendFunction(this.blending.functionDestinationAlpha)) {
      throw new DeveloperError(
        "Invalid renderState.blending.functionDestinationAlpha."
      );
    }
    if (!validateStencilFunction(this.stencilTest.frontFunction)) {
      throw new DeveloperError("Invalid renderState.stencilTest.frontFunction.");
    }
    if (!validateStencilFunction(this.stencilTest.backFunction)) {
      throw new DeveloperError("Invalid renderState.stencilTest.backFunction.");
    }
    if (!validateStencilOperation(this.stencilTest.frontOperation.fail)) {
      throw new DeveloperError(
        "Invalid renderState.stencilTest.frontOperation.fail."
      );
    }
    if (!validateStencilOperation(this.stencilTest.frontOperation.zFail)) {
      throw new DeveloperError(
        "Invalid renderState.stencilTest.frontOperation.zFail."
      );
    }
    if (!validateStencilOperation(this.stencilTest.frontOperation.zPass)) {
      throw new DeveloperError(
        "Invalid renderState.stencilTest.frontOperation.zPass."
      );
    }
    if (!validateStencilOperation(this.stencilTest.backOperation.fail)) {
      throw new DeveloperError(
        "Invalid renderState.stencilTest.backOperation.fail."
      );
    }
    if (!validateStencilOperation(this.stencilTest.backOperation.zFail)) {
      throw new DeveloperError(
        "Invalid renderState.stencilTest.backOperation.zFail."
      );
    }
    if (!validateStencilOperation(this.stencilTest.backOperation.zPass)) {
      throw new DeveloperError(
        "Invalid renderState.stencilTest.backOperation.zPass."
      );
    }

    if (defined(this.viewport)) {
      if (this.viewport.width < 0) {
        throw new DeveloperError(
          "renderState.viewport.width must be greater than or equal to zero."
        );
      }
      if (this.viewport.height < 0) {
        throw new DeveloperError(
          "renderState.viewport.height must be greater than or equal to zero."
        );
      }

      if (this.viewport.width > ContextLimits.maximumViewportWidth) {
        throw new DeveloperError(
          "renderState.viewport.width must be less than or equal to the maximum viewport width (" +
            ContextLimits.maximumViewportWidth.toString() +
            ").  Check maximumViewportWidth."
        );
      }
      if (this.viewport.height > ContextLimits.maximumViewportHeight) {
        throw new DeveloperError(
          "renderState.viewport.height must be less than or equal to the maximum viewport height (" +
            ContextLimits.maximumViewportHeight.toString() +
            ").  Check maximumViewportHeight."
        );
      }
    }
    //>>includeEnd('debug');

    this.id = 0;
    this._applyFunctions = [];
  }

  var nextRenderStateId = 0;
  var renderStateCache = {};

  /**
   * Validates and then finds or creates an immutable render state, which defines the pipeline
   * state for a {@link DrawCommand} or {@link ClearCommand}.  All inputs states are optional.  Omitted states
   * use the defaults shown in the example below.
   *
   * @param {Object} [renderState] The states defining the render state as shown in the example below.
   *
   * @exception {RuntimeError} renderState.lineWidth is out of range.
   * @exception {DeveloperError} Invalid renderState.frontFace.
   * @exception {DeveloperError} Invalid renderState.cull.face.
   * @exception {DeveloperError} scissorTest.rectangle.width and scissorTest.rectangle.height must be greater than or equal to zero.
   * @exception {DeveloperError} renderState.depthRange.near can't be greater than renderState.depthRange.far.
   * @exception {DeveloperError} renderState.depthRange.near must be greater than or equal to zero.
   * @exception {DeveloperError} renderState.depthRange.far must be less than or equal to zero.
   * @exception {DeveloperError} Invalid renderState.depthTest.func.
   * @exception {DeveloperError} renderState.blending.color components must be greater than or equal to zero and less than or equal to one
   * @exception {DeveloperError} Invalid renderState.blending.equationRgb.
   * @exception {DeveloperError} Invalid renderState.blending.equationAlpha.
   * @exception {DeveloperError} Invalid renderState.blending.functionSourceRgb.
   * @exception {DeveloperError} Invalid renderState.blending.functionSourceAlpha.
   * @exception {DeveloperError} Invalid renderState.blending.functionDestinationRgb.
   * @exception {DeveloperError} Invalid renderState.blending.functionDestinationAlpha.
   * @exception {DeveloperError} Invalid renderState.stencilTest.frontFunction.
   * @exception {DeveloperError} Invalid renderState.stencilTest.backFunction.
   * @exception {DeveloperError} Invalid renderState.stencilTest.frontOperation.fail.
   * @exception {DeveloperError} Invalid renderState.stencilTest.frontOperation.zFail.
   * @exception {DeveloperError} Invalid renderState.stencilTest.frontOperation.zPass.
   * @exception {DeveloperError} Invalid renderState.stencilTest.backOperation.fail.
   * @exception {DeveloperError} Invalid renderState.stencilTest.backOperation.zFail.
   * @exception {DeveloperError} Invalid renderState.stencilTest.backOperation.zPass.
   * @exception {DeveloperError} renderState.viewport.width must be greater than or equal to zero.
   * @exception {DeveloperError} renderState.viewport.width must be less than or equal to the maximum viewport width.
   * @exception {DeveloperError} renderState.viewport.height must be greater than or equal to zero.
   * @exception {DeveloperError} renderState.viewport.height must be less than or equal to the maximum viewport height.
   *
   *
   * @example
   * var defaults = {
   *     frontFace : WindingOrder.COUNTER_CLOCKWISE,
   *     cull : {
   *         enabled : false,
   *         face : CullFace.BACK
   *     },
   *     lineWidth : 1,
   *     polygonOffset : {
   *         enabled : false,
   *         factor : 0,
   *         units : 0
   *     },
   *     scissorTest : {
   *         enabled : false,
   *         rectangle : {
   *             x : 0,
   *             y : 0,
   *             width : 0,
   *             height : 0
   *         }
   *     },
   *     depthRange : {
   *         near : 0,
   *         far : 1
   *     },
   *     depthTest : {
   *         enabled : false,
   *         func : DepthFunction.LESS
   *      },
   *     colorMask : {
   *         red : true,
   *         green : true,
   *         blue : true,
   *         alpha : true
   *     },
   *     depthMask : true,
   *     stencilMask : ~0,
   *     blending : {
   *         enabled : false,
   *         color : {
   *             red : 0.0,
   *             green : 0.0,
   *             blue : 0.0,
   *             alpha : 0.0
   *         },
   *         equationRgb : BlendEquation.ADD,
   *         equationAlpha : BlendEquation.ADD,
   *         functionSourceRgb : BlendFunction.ONE,
   *         functionSourceAlpha : BlendFunction.ONE,
   *         functionDestinationRgb : BlendFunction.ZERO,
   *         functionDestinationAlpha : BlendFunction.ZERO
   *     },
   *     stencilTest : {
   *         enabled : false,
   *         frontFunction : StencilFunction.ALWAYS,
   *         backFunction : StencilFunction.ALWAYS,
   *         reference : 0,
   *         mask : ~0,
   *         frontOperation : {
   *             fail : StencilOperation.KEEP,
   *             zFail : StencilOperation.KEEP,
   *             zPass : StencilOperation.KEEP
   *         },
   *         backOperation : {
   *             fail : StencilOperation.KEEP,
   *             zFail : StencilOperation.KEEP,
   *             zPass : StencilOperation.KEEP
   *         }
   *     },
   *     sampleCoverage : {
   *         enabled : false,
   *         value : 1.0,
   *         invert : false
   *      }
   * };
   *
   * var rs = RenderState.fromCache(defaults);
   *
   * @see DrawCommand
   * @see ClearCommand
   *
   * @private
   */
  RenderState.fromCache = function (renderState) {
    var partialKey = JSON.stringify(renderState);
    var cachedState = renderStateCache[partialKey];
    if (defined(cachedState)) {
      ++cachedState.referenceCount;
      return cachedState.state;
    }

    // Cache miss.  Fully define render state and try again.
    var states = new RenderState(renderState);
    var fullKey = JSON.stringify(states);
    cachedState = renderStateCache[fullKey];
    if (!defined(cachedState)) {
      states.id = nextRenderStateId++;
      //>>includeStart('debug', pragmas.debug);
      states = freezeRenderState(states);
      //>>includeEnd('debug');
      cachedState = {
        referenceCount: 0,
        state: states,
      };

      // Cache full render state.  Multiple partially defined render states may map to this.
      renderStateCache[fullKey] = cachedState;
    }

    ++cachedState.referenceCount;

    // Cache partial render state so we can skip validation on a cache hit for a partially defined render state
    renderStateCache[partialKey] = {
      referenceCount: 1,
      state: cachedState.state,
    };

    return cachedState.state;
  };

  /**
   * @private
   */
  RenderState.removeFromCache = function (renderState) {
    var states = new RenderState(renderState);
    var fullKey = JSON.stringify(states);
    var fullCachedState = renderStateCache[fullKey];

    // decrement partial key reference count
    var partialKey = JSON.stringify(renderState);
    var cachedState = renderStateCache[partialKey];
    if (defined(cachedState)) {
      --cachedState.referenceCount;

      if (cachedState.referenceCount === 0) {
        // remove partial key
        delete renderStateCache[partialKey];

        // decrement full key reference count
        if (defined(fullCachedState)) {
          --fullCachedState.referenceCount;
        }
      }
    }

    // remove full key if reference count is zero
    if (defined(fullCachedState) && fullCachedState.referenceCount === 0) {
      delete renderStateCache[fullKey];
    }
  };

  /**
   * This function is for testing purposes only.
   * @private
   */
  RenderState.getCache = function () {
    return renderStateCache;
  };

  /**
   * This function is for testing purposes only.
   * @private
   */
  RenderState.clearCache = function () {
    renderStateCache = {};
  };

  function enableOrDisable(gl, glEnum, enable) {
    if (enable) {
      gl.enable(glEnum);
    } else {
      gl.disable(glEnum);
    }
  }

  function applyFrontFace(gl, renderState) {
    gl.frontFace(renderState.frontFace);
  }

  function applyCull(gl, renderState) {
    var cull = renderState.cull;
    var enabled = cull.enabled;

    enableOrDisable(gl, gl.CULL_FACE, enabled);

    if (enabled) {
      gl.cullFace(cull.face);
    }
  }

  function applyLineWidth(gl, renderState) {
    gl.lineWidth(renderState.lineWidth);
  }

  function applyPolygonOffset(gl, renderState) {
    var polygonOffset = renderState.polygonOffset;
    var enabled = polygonOffset.enabled;

    enableOrDisable(gl, gl.POLYGON_OFFSET_FILL, enabled);

    if (enabled) {
      gl.polygonOffset(polygonOffset.factor, polygonOffset.units);
    }
  }

  function applyScissorTest(gl, renderState, passState) {
    var scissorTest = renderState.scissorTest;
    var enabled = defined(passState.scissorTest)
      ? passState.scissorTest.enabled
      : scissorTest.enabled;

    enableOrDisable(gl, gl.SCISSOR_TEST, enabled);

    if (enabled) {
      var rectangle = defined(passState.scissorTest)
        ? passState.scissorTest.rectangle
        : scissorTest.rectangle;
      gl.scissor(rectangle.x, rectangle.y, rectangle.width, rectangle.height);
    }
  }

  function applyDepthRange(gl, renderState) {
    var depthRange = renderState.depthRange;
    gl.depthRange(depthRange.near, depthRange.far);
  }

  function applyDepthTest(gl, renderState) {
    var depthTest = renderState.depthTest;
    var enabled = depthTest.enabled;

    enableOrDisable(gl, gl.DEPTH_TEST, enabled);

    if (enabled) {
      gl.depthFunc(depthTest.func);
    }
  }

  function applyColorMask(gl, renderState) {
    var colorMask = renderState.colorMask;
    gl.colorMask(colorMask.red, colorMask.green, colorMask.blue, colorMask.alpha);
  }

  function applyDepthMask(gl, renderState) {
    gl.depthMask(renderState.depthMask);
  }

  function applyStencilMask(gl, renderState) {
    gl.stencilMask(renderState.stencilMask);
  }

  function applyBlendingColor(gl, color) {
    gl.blendColor(color.red, color.green, color.blue, color.alpha);
  }

  function applyBlending(gl, renderState, passState) {
    var blending = renderState.blending;
    var enabled = defined(passState.blendingEnabled)
      ? passState.blendingEnabled
      : blending.enabled;

    enableOrDisable(gl, gl.BLEND, enabled);

    if (enabled) {
      applyBlendingColor(gl, blending.color);
      gl.blendEquationSeparate(blending.equationRgb, blending.equationAlpha);
      gl.blendFuncSeparate(
        blending.functionSourceRgb,
        blending.functionDestinationRgb,
        blending.functionSourceAlpha,
        blending.functionDestinationAlpha
      );
    }
  }

  function applyStencilTest(gl, renderState) {
    var stencilTest = renderState.stencilTest;
    var enabled = stencilTest.enabled;

    enableOrDisable(gl, gl.STENCIL_TEST, enabled);

    if (enabled) {
      var frontFunction = stencilTest.frontFunction;
      var backFunction = stencilTest.backFunction;
      var reference = stencilTest.reference;
      var mask = stencilTest.mask;

      // Section 6.8 of the WebGL spec requires the reference and masks to be the same for
      // front- and back-face tests.  This call prevents invalid operation errors when calling
      // stencilFuncSeparate on Firefox.  Perhaps they should delay validation to avoid requiring this.
      gl.stencilFunc(frontFunction, reference, mask);
      gl.stencilFuncSeparate(gl.BACK, backFunction, reference, mask);
      gl.stencilFuncSeparate(gl.FRONT, frontFunction, reference, mask);

      var frontOperation = stencilTest.frontOperation;
      var frontOperationFail = frontOperation.fail;
      var frontOperationZFail = frontOperation.zFail;
      var frontOperationZPass = frontOperation.zPass;

      gl.stencilOpSeparate(
        gl.FRONT,
        frontOperationFail,
        frontOperationZFail,
        frontOperationZPass
      );

      var backOperation = stencilTest.backOperation;
      var backOperationFail = backOperation.fail;
      var backOperationZFail = backOperation.zFail;
      var backOperationZPass = backOperation.zPass;

      gl.stencilOpSeparate(
        gl.BACK,
        backOperationFail,
        backOperationZFail,
        backOperationZPass
      );
    }
  }

  function applySampleCoverage(gl, renderState) {
    var sampleCoverage = renderState.sampleCoverage;
    var enabled = sampleCoverage.enabled;

    enableOrDisable(gl, gl.SAMPLE_COVERAGE, enabled);

    if (enabled) {
      gl.sampleCoverage(sampleCoverage.value, sampleCoverage.invert);
    }
  }

  var scratchViewport = new BoundingRectangle();

  function applyViewport(gl, renderState, passState) {
    var viewport = defaultValue(renderState.viewport, passState.viewport);
    if (!defined(viewport)) {
      viewport = scratchViewport;
      viewport.width = passState.context.drawingBufferWidth;
      viewport.height = passState.context.drawingBufferHeight;
    }

    passState.context.uniformState.viewport = viewport;
    gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height);
  }

  RenderState.apply = function (gl, renderState, passState) {
    applyFrontFace(gl, renderState);
    applyCull(gl, renderState);
    applyLineWidth(gl, renderState);
    applyPolygonOffset(gl, renderState);
    applyDepthRange(gl, renderState);
    applyDepthTest(gl, renderState);
    applyColorMask(gl, renderState);
    applyDepthMask(gl, renderState);
    applyStencilMask(gl, renderState);
    applyStencilTest(gl, renderState);
    applySampleCoverage(gl, renderState);
    applyScissorTest(gl, renderState, passState);
    applyBlending(gl, renderState, passState);
    applyViewport(gl, renderState, passState);
  };

  function createFuncs(previousState, nextState) {
    var funcs = [];

    if (previousState.frontFace !== nextState.frontFace) {
      funcs.push(applyFrontFace);
    }

    if (
      previousState.cull.enabled !== nextState.cull.enabled ||
      previousState.cull.face !== nextState.cull.face
    ) {
      funcs.push(applyCull);
    }

    if (previousState.lineWidth !== nextState.lineWidth) {
      funcs.push(applyLineWidth);
    }

    if (
      previousState.polygonOffset.enabled !== nextState.polygonOffset.enabled ||
      previousState.polygonOffset.factor !== nextState.polygonOffset.factor ||
      previousState.polygonOffset.units !== nextState.polygonOffset.units
    ) {
      funcs.push(applyPolygonOffset);
    }

    if (
      previousState.depthRange.near !== nextState.depthRange.near ||
      previousState.depthRange.far !== nextState.depthRange.far
    ) {
      funcs.push(applyDepthRange);
    }

    if (
      previousState.depthTest.enabled !== nextState.depthTest.enabled ||
      previousState.depthTest.func !== nextState.depthTest.func
    ) {
      funcs.push(applyDepthTest);
    }

    if (
      previousState.colorMask.red !== nextState.colorMask.red ||
      previousState.colorMask.green !== nextState.colorMask.green ||
      previousState.colorMask.blue !== nextState.colorMask.blue ||
      previousState.colorMask.alpha !== nextState.colorMask.alpha
    ) {
      funcs.push(applyColorMask);
    }

    if (previousState.depthMask !== nextState.depthMask) {
      funcs.push(applyDepthMask);
    }

    if (previousState.stencilMask !== nextState.stencilMask) {
      funcs.push(applyStencilMask);
    }

    if (
      previousState.stencilTest.enabled !== nextState.stencilTest.enabled ||
      previousState.stencilTest.frontFunction !==
        nextState.stencilTest.frontFunction ||
      previousState.stencilTest.backFunction !==
        nextState.stencilTest.backFunction ||
      previousState.stencilTest.reference !== nextState.stencilTest.reference ||
      previousState.stencilTest.mask !== nextState.stencilTest.mask ||
      previousState.stencilTest.frontOperation.fail !==
        nextState.stencilTest.frontOperation.fail ||
      previousState.stencilTest.frontOperation.zFail !==
        nextState.stencilTest.frontOperation.zFail ||
      previousState.stencilTest.backOperation.fail !==
        nextState.stencilTest.backOperation.fail ||
      previousState.stencilTest.backOperation.zFail !==
        nextState.stencilTest.backOperation.zFail ||
      previousState.stencilTest.backOperation.zPass !==
        nextState.stencilTest.backOperation.zPass
    ) {
      funcs.push(applyStencilTest);
    }

    if (
      previousState.sampleCoverage.enabled !== nextState.sampleCoverage.enabled ||
      previousState.sampleCoverage.value !== nextState.sampleCoverage.value ||
      previousState.sampleCoverage.invert !== nextState.sampleCoverage.invert
    ) {
      funcs.push(applySampleCoverage);
    }

    return funcs;
  }

  RenderState.partialApply = function (
    gl,
    previousRenderState,
    renderState,
    previousPassState,
    passState,
    clear
  ) {
    if (previousRenderState !== renderState) {
      // When a new render state is applied, instead of making WebGL calls for all the states or first
      // comparing the states one-by-one with the previous state (basically a linear search), we take
      // advantage of RenderState's immutability, and store a dynamically populated sparse data structure
      // containing functions that make the minimum number of WebGL calls when transitioning from one state
      // to the other.  In practice, this works well since state-to-state transitions generally only require a
      // few WebGL calls, especially if commands are stored by state.
      var funcs = renderState._applyFunctions[previousRenderState.id];
      if (!defined(funcs)) {
        funcs = createFuncs(previousRenderState, renderState);
        renderState._applyFunctions[previousRenderState.id] = funcs;
      }

      var len = funcs.length;
      for (var i = 0; i < len; ++i) {
        funcs[i](gl, renderState);
      }
    }

    var previousScissorTest = defined(previousPassState.scissorTest)
      ? previousPassState.scissorTest
      : previousRenderState.scissorTest;
    var scissorTest = defined(passState.scissorTest)
      ? passState.scissorTest
      : renderState.scissorTest;

    // Our scissor rectangle can get out of sync with the GL scissor rectangle on clears.
    // Seems to be a problem only on ANGLE. See https://github.com/CesiumGS/cesium/issues/2994
    if (previousScissorTest !== scissorTest || clear) {
      applyScissorTest(gl, renderState, passState);
    }

    var previousBlendingEnabled = defined(previousPassState.blendingEnabled)
      ? previousPassState.blendingEnabled
      : previousRenderState.blending.enabled;
    var blendingEnabled = defined(passState.blendingEnabled)
      ? passState.blendingEnabled
      : renderState.blending.enabled;
    if (
      previousBlendingEnabled !== blendingEnabled ||
      (blendingEnabled && previousRenderState.blending !== renderState.blending)
    ) {
      applyBlending(gl, renderState, passState);
    }

    if (
      previousRenderState !== renderState ||
      previousPassState !== passState ||
      previousPassState.context !== passState.context
    ) {
      applyViewport(gl, renderState, passState);
    }
  };

  RenderState.getState = function (renderState) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(renderState)) {
      throw new DeveloperError("renderState is required.");
    }
    //>>includeEnd('debug');

    return {
      frontFace: renderState.frontFace,
      cull: {
        enabled: renderState.cull.enabled,
        face: renderState.cull.face,
      },
      lineWidth: renderState.lineWidth,
      polygonOffset: {
        enabled: renderState.polygonOffset.enabled,
        factor: renderState.polygonOffset.factor,
        units: renderState.polygonOffset.units,
      },
      scissorTest: {
        enabled: renderState.scissorTest.enabled,
        rectangle: BoundingRectangle.clone(renderState.scissorTest.rectangle),
      },
      depthRange: {
        near: renderState.depthRange.near,
        far: renderState.depthRange.far,
      },
      depthTest: {
        enabled: renderState.depthTest.enabled,
        func: renderState.depthTest.func,
      },
      colorMask: {
        red: renderState.colorMask.red,
        green: renderState.colorMask.green,
        blue: renderState.colorMask.blue,
        alpha: renderState.colorMask.alpha,
      },
      depthMask: renderState.depthMask,
      stencilMask: renderState.stencilMask,
      blending: {
        enabled: renderState.blending.enabled,
        color: Color.clone(renderState.blending.color),
        equationRgb: renderState.blending.equationRgb,
        equationAlpha: renderState.blending.equationAlpha,
        functionSourceRgb: renderState.blending.functionSourceRgb,
        functionSourceAlpha: renderState.blending.functionSourceAlpha,
        functionDestinationRgb: renderState.blending.functionDestinationRgb,
        functionDestinationAlpha: renderState.blending.functionDestinationAlpha,
      },
      stencilTest: {
        enabled: renderState.stencilTest.enabled,
        frontFunction: renderState.stencilTest.frontFunction,
        backFunction: renderState.stencilTest.backFunction,
        reference: renderState.stencilTest.reference,
        mask: renderState.stencilTest.mask,
        frontOperation: {
          fail: renderState.stencilTest.frontOperation.fail,
          zFail: renderState.stencilTest.frontOperation.zFail,
          zPass: renderState.stencilTest.frontOperation.zPass,
        },
        backOperation: {
          fail: renderState.stencilTest.backOperation.fail,
          zFail: renderState.stencilTest.backOperation.zFail,
          zPass: renderState.stencilTest.backOperation.zPass,
        },
      },
      sampleCoverage: {
        enabled: renderState.sampleCoverage.enabled,
        value: renderState.sampleCoverage.value,
        invert: renderState.sampleCoverage.invert,
      },
      viewport: defined(renderState.viewport)
        ? BoundingRectangle.clone(renderState.viewport)
        : undefined,
    };
  };

  var viewerPositionWCScratch = new Cartesian3();

  function AutomaticUniform(options) {
    this._size = options.size;
    this._datatype = options.datatype;
    this.getValue = options.getValue;
  }

  var datatypeToGlsl = {};
  datatypeToGlsl[WebGLConstants$1.FLOAT] = "float";
  datatypeToGlsl[WebGLConstants$1.FLOAT_VEC2] = "vec2";
  datatypeToGlsl[WebGLConstants$1.FLOAT_VEC3] = "vec3";
  datatypeToGlsl[WebGLConstants$1.FLOAT_VEC4] = "vec4";
  datatypeToGlsl[WebGLConstants$1.INT] = "int";
  datatypeToGlsl[WebGLConstants$1.INT_VEC2] = "ivec2";
  datatypeToGlsl[WebGLConstants$1.INT_VEC3] = "ivec3";
  datatypeToGlsl[WebGLConstants$1.INT_VEC4] = "ivec4";
  datatypeToGlsl[WebGLConstants$1.BOOL] = "bool";
  datatypeToGlsl[WebGLConstants$1.BOOL_VEC2] = "bvec2";
  datatypeToGlsl[WebGLConstants$1.BOOL_VEC3] = "bvec3";
  datatypeToGlsl[WebGLConstants$1.BOOL_VEC4] = "bvec4";
  datatypeToGlsl[WebGLConstants$1.FLOAT_MAT2] = "mat2";
  datatypeToGlsl[WebGLConstants$1.FLOAT_MAT3] = "mat3";
  datatypeToGlsl[WebGLConstants$1.FLOAT_MAT4] = "mat4";
  datatypeToGlsl[WebGLConstants$1.SAMPLER_2D] = "sampler2D";
  datatypeToGlsl[WebGLConstants$1.SAMPLER_CUBE] = "samplerCube";

  AutomaticUniform.prototype.getDeclaration = function (name) {
    var declaration = "uniform " + datatypeToGlsl[this._datatype] + " " + name;

    var size = this._size;
    if (size === 1) {
      declaration += ";";
    } else {
      declaration += "[" + size.toString() + "];";
    }

    return declaration;
  };

  /**
   * @private
   */
  var AutomaticUniforms = {
    /**
     * An automatic GLSL uniform containing the viewport's <code>x</code>, <code>y</code>, <code>width</code>,
     * and <code>height</code> properties in an <code>vec4</code>'s <code>x</code>, <code>y</code>, <code>z</code>,
     * and <code>w</code> components, respectively.
     *
     * @example
     * // GLSL declaration
     * uniform vec4 czm_viewport;
     *
     * // Scale the window coordinate components to [0, 1] by dividing
     * // by the viewport's width and height.
     * vec2 v = gl_FragCoord.xy / czm_viewport.zw;
     *
     * @see Context#getViewport
     */
    czm_viewport: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC4,
      getValue: function (uniformState) {
        return uniformState.viewportCartesian4;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 orthographic projection matrix that
     * transforms window coordinates to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     * <br /><br />
     * This transform is useful when a vertex shader inputs or manipulates window coordinates
     * as done by {@link BillboardCollection}.
     * <br /><br />
     * Do not confuse {@link czm_viewportTransformation} with <code>czm_viewportOrthographic</code>.
     * The former transforms from normalized device coordinates to window coordinates; the later transforms
     * from window coordinates to clip coordinates, and is often used to assign to <code>gl_Position</code>.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_viewportOrthographic;
     *
     * // Example
     * gl_Position = czm_viewportOrthographic * vec4(windowPosition, 0.0, 1.0);
     *
     * @see UniformState#viewportOrthographic
     * @see czm_viewport
     * @see czm_viewportTransformation
     * @see BillboardCollection
     */
    czm_viewportOrthographic: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.viewportOrthographic;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 transformation matrix that
     * transforms normalized device coordinates to window coordinates.  The context's
     * full viewport is used, and the depth range is assumed to be <code>near = 0</code>
     * and <code>far = 1</code>.
     * <br /><br />
     * This transform is useful when there is a need to manipulate window coordinates
     * in a vertex shader as done by {@link BillboardCollection}.  In many cases,
     * this matrix will not be used directly; instead, {@link czm_modelToWindowCoordinates}
     * will be used to transform directly from model to window coordinates.
     * <br /><br />
     * Do not confuse <code>czm_viewportTransformation</code> with {@link czm_viewportOrthographic}.
     * The former transforms from normalized device coordinates to window coordinates; the later transforms
     * from window coordinates to clip coordinates, and is often used to assign to <code>gl_Position</code>.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_viewportTransformation;
     *
     * // Use czm_viewportTransformation as part of the
     * // transform from model to window coordinates.
     * vec4 q = czm_modelViewProjection * positionMC;               // model to clip coordinates
     * q.xyz /= q.w;                                                // clip to normalized device coordinates (ndc)
     * q.xyz = (czm_viewportTransformation * vec4(q.xyz, 1.0)).xyz; // ndc to window coordinates
     *
     * @see UniformState#viewportTransformation
     * @see czm_viewport
     * @see czm_viewportOrthographic
     * @see czm_modelToWindowCoordinates
     * @see BillboardCollection
     */
    czm_viewportTransformation: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.viewportTransformation;
      },
    }),

    /**
     * An automatic GLSL uniform representing the depth of the scene
     * after the globe pass and then updated after the 3D Tiles pass.
     * The depth is packed into an RGBA texture.
     *
     * @example
     * // GLSL declaration
     * uniform sampler2D czm_globeDepthTexture;
     *
     * // Get the depth at the current fragment
     * vec2 coords = gl_FragCoord.xy / czm_viewport.zw;
     * float depth = czm_unpackDepth(texture2D(czm_globeDepthTexture, coords));
     */
    czm_globeDepthTexture: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.SAMPLER_2D,
      getValue: function (uniformState) {
        return uniformState.globeDepthTexture;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model transformation matrix that
     * transforms model coordinates to world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_model;
     *
     * // Example
     * vec4 worldPosition = czm_model * modelPosition;
     *
     * @see UniformState#model
     * @see czm_inverseModel
     * @see czm_modelView
     * @see czm_modelViewProjection
     */
    czm_model: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.model;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model transformation matrix that
     * transforms world coordinates to model coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseModel;
     *
     * // Example
     * vec4 modelPosition = czm_inverseModel * worldPosition;
     *
     * @see UniformState#inverseModel
     * @see czm_model
     * @see czm_inverseModelView
     */
    czm_inverseModel: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseModel;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 view transformation matrix that
     * transforms world coordinates to eye coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_view;
     *
     * // Example
     * vec4 eyePosition = czm_view * worldPosition;
     *
     * @see UniformState#view
     * @see czm_viewRotation
     * @see czm_modelView
     * @see czm_viewProjection
     * @see czm_modelViewProjection
     * @see czm_inverseView
     */
    czm_view: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.view;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 view transformation matrix that
     * transforms 3D world coordinates to eye coordinates.  In 3D mode, this is identical to
     * {@link czm_view}, but in 2D and Columbus View it represents the view matrix
     * as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_view3D;
     *
     * // Example
     * vec4 eyePosition3D = czm_view3D * worldPosition3D;
     *
     * @see UniformState#view3D
     * @see czm_view
     */
    czm_view3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.view3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 view rotation matrix that
     * transforms vectors in world coordinates to eye coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_viewRotation;
     *
     * // Example
     * vec3 eyeVector = czm_viewRotation * worldVector;
     *
     * @see UniformState#viewRotation
     * @see czm_view
     * @see czm_inverseView
     * @see czm_inverseViewRotation
     */
    czm_viewRotation: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.viewRotation;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 view rotation matrix that
     * transforms vectors in 3D world coordinates to eye coordinates.  In 3D mode, this is identical to
     * {@link czm_viewRotation}, but in 2D and Columbus View it represents the view matrix
     * as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_viewRotation3D;
     *
     * // Example
     * vec3 eyeVector = czm_viewRotation3D * worldVector;
     *
     * @see UniformState#viewRotation3D
     * @see czm_viewRotation
     */
    czm_viewRotation3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.viewRotation3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 transformation matrix that
     * transforms from eye coordinates to world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseView;
     *
     * // Example
     * vec4 worldPosition = czm_inverseView * eyePosition;
     *
     * @see UniformState#inverseView
     * @see czm_view
     * @see czm_inverseNormal
     */
    czm_inverseView: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseView;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 transformation matrix that
     * transforms from 3D eye coordinates to world coordinates.  In 3D mode, this is identical to
     * {@link czm_inverseView}, but in 2D and Columbus View it represents the inverse view matrix
     * as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseView3D;
     *
     * // Example
     * vec4 worldPosition = czm_inverseView3D * eyePosition;
     *
     * @see UniformState#inverseView3D
     * @see czm_inverseView
     */
    czm_inverseView3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseView3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 rotation matrix that
     * transforms vectors from eye coordinates to world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_inverseViewRotation;
     *
     * // Example
     * vec4 worldVector = czm_inverseViewRotation * eyeVector;
     *
     * @see UniformState#inverseView
     * @see czm_view
     * @see czm_viewRotation
     * @see czm_inverseViewRotation
     */
    czm_inverseViewRotation: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.inverseViewRotation;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 rotation matrix that
     * transforms vectors from 3D eye coordinates to world coordinates.  In 3D mode, this is identical to
     * {@link czm_inverseViewRotation}, but in 2D and Columbus View it represents the inverse view matrix
     * as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_inverseViewRotation3D;
     *
     * // Example
     * vec4 worldVector = czm_inverseViewRotation3D * eyeVector;
     *
     * @see UniformState#inverseView3D
     * @see czm_inverseViewRotation
     */
    czm_inverseViewRotation3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.inverseViewRotation3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 projection transformation matrix that
     * transforms eye coordinates to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_projection;
     *
     * // Example
     * gl_Position = czm_projection * eyePosition;
     *
     * @see UniformState#projection
     * @see czm_viewProjection
     * @see czm_modelViewProjection
     * @see czm_infiniteProjection
     */
    czm_projection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.projection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 inverse projection transformation matrix that
     * transforms from clip coordinates to eye coordinates. Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseProjection;
     *
     * // Example
     * vec4 eyePosition = czm_inverseProjection * clipPosition;
     *
     * @see UniformState#inverseProjection
     * @see czm_projection
     */
    czm_inverseProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseProjection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 projection transformation matrix with the far plane at infinity,
     * that transforms eye coordinates to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.  An infinite far plane is used
     * in algorithms like shadow volumes and GPU ray casting with proxy geometry to ensure that triangles
     * are not clipped by the far plane.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_infiniteProjection;
     *
     * // Example
     * gl_Position = czm_infiniteProjection * eyePosition;
     *
     * @see UniformState#infiniteProjection
     * @see czm_projection
     * @see czm_modelViewInfiniteProjection
     */
    czm_infiniteProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.infiniteProjection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model-view transformation matrix that
     * transforms model coordinates to eye coordinates.
     * <br /><br />
     * Positions should be transformed to eye coordinates using <code>czm_modelView</code> and
     * normals should be transformed using {@link czm_normal}.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_modelView;
     *
     * // Example
     * vec4 eyePosition = czm_modelView * modelPosition;
     *
     * // The above is equivalent to, but more efficient than:
     * vec4 eyePosition = czm_view * czm_model * modelPosition;
     *
     * @see UniformState#modelView
     * @see czm_model
     * @see czm_view
     * @see czm_modelViewProjection
     * @see czm_normal
     */
    czm_modelView: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.modelView;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model-view transformation matrix that
     * transforms 3D model coordinates to eye coordinates.  In 3D mode, this is identical to
     * {@link czm_modelView}, but in 2D and Columbus View it represents the model-view matrix
     * as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     * <br /><br />
     * Positions should be transformed to eye coordinates using <code>czm_modelView3D</code> and
     * normals should be transformed using {@link czm_normal3D}.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_modelView3D;
     *
     * // Example
     * vec4 eyePosition = czm_modelView3D * modelPosition;
     *
     * // The above is equivalent to, but more efficient than:
     * vec4 eyePosition = czm_view3D * czm_model * modelPosition;
     *
     * @see UniformState#modelView3D
     * @see czm_modelView
     */
    czm_modelView3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.modelView3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model-view transformation matrix that
     * transforms model coordinates, relative to the eye, to eye coordinates.  This is used
     * in conjunction with {@link czm_translateRelativeToEye}.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_modelViewRelativeToEye;
     *
     * // Example
     * attribute vec3 positionHigh;
     * attribute vec3 positionLow;
     *
     * void main()
     * {
     *   vec4 p = czm_translateRelativeToEye(positionHigh, positionLow);
     *   gl_Position = czm_projection * (czm_modelViewRelativeToEye * p);
     * }
     *
     * @see czm_modelViewProjectionRelativeToEye
     * @see czm_translateRelativeToEye
     * @see EncodedCartesian3
     */
    czm_modelViewRelativeToEye: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.modelViewRelativeToEye;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 transformation matrix that
     * transforms from eye coordinates to model coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseModelView;
     *
     * // Example
     * vec4 modelPosition = czm_inverseModelView * eyePosition;
     *
     * @see UniformState#inverseModelView
     * @see czm_modelView
     */
    czm_inverseModelView: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseModelView;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 transformation matrix that
     * transforms from eye coordinates to 3D model coordinates.  In 3D mode, this is identical to
     * {@link czm_inverseModelView}, but in 2D and Columbus View it represents the inverse model-view matrix
     * as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseModelView3D;
     *
     * // Example
     * vec4 modelPosition = czm_inverseModelView3D * eyePosition;
     *
     * @see UniformState#inverseModelView
     * @see czm_inverseModelView
     * @see czm_modelView3D
     */
    czm_inverseModelView3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseModelView3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 view-projection transformation matrix that
     * transforms world coordinates to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_viewProjection;
     *
     * // Example
     * vec4 gl_Position = czm_viewProjection * czm_model * modelPosition;
     *
     * // The above is equivalent to, but more efficient than:
     * gl_Position = czm_projection * czm_view * czm_model * modelPosition;
     *
     * @see UniformState#viewProjection
     * @see czm_view
     * @see czm_projection
     * @see czm_modelViewProjection
     * @see czm_inverseViewProjection
     */
    czm_viewProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.viewProjection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 view-projection transformation matrix that
     * transforms clip coordinates to world coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseViewProjection;
     *
     * // Example
     * vec4 worldPosition = czm_inverseViewProjection * clipPosition;
     *
     * @see UniformState#inverseViewProjection
     * @see czm_viewProjection
     */
    czm_inverseViewProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseViewProjection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model-view-projection transformation matrix that
     * transforms model coordinates to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_modelViewProjection;
     *
     * // Example
     * vec4 gl_Position = czm_modelViewProjection * modelPosition;
     *
     * // The above is equivalent to, but more efficient than:
     * gl_Position = czm_projection * czm_view * czm_model * modelPosition;
     *
     * @see UniformState#modelViewProjection
     * @see czm_model
     * @see czm_view
     * @see czm_projection
     * @see czm_modelView
     * @see czm_viewProjection
     * @see czm_modelViewInfiniteProjection
     * @see czm_inverseModelViewProjection
     */
    czm_modelViewProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.modelViewProjection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 inverse model-view-projection transformation matrix that
     * transforms clip coordinates to model coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_inverseModelViewProjection;
     *
     * // Example
     * vec4 modelPosition = czm_inverseModelViewProjection * clipPosition;
     *
     * @see UniformState#modelViewProjection
     * @see czm_modelViewProjection
     */
    czm_inverseModelViewProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.inverseModelViewProjection;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model-view-projection transformation matrix that
     * transforms model coordinates, relative to the eye, to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.  This is used in
     * conjunction with {@link czm_translateRelativeToEye}.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_modelViewProjectionRelativeToEye;
     *
     * // Example
     * attribute vec3 positionHigh;
     * attribute vec3 positionLow;
     *
     * void main()
     * {
     *   vec4 p = czm_translateRelativeToEye(positionHigh, positionLow);
     *   gl_Position = czm_modelViewProjectionRelativeToEye * p;
     * }
     *
     * @see czm_modelViewRelativeToEye
     * @see czm_translateRelativeToEye
     * @see EncodedCartesian3
     */
    czm_modelViewProjectionRelativeToEye: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.modelViewProjectionRelativeToEye;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 4x4 model-view-projection transformation matrix that
     * transforms model coordinates to clip coordinates.  Clip coordinates is the
     * coordinate system for a vertex shader's <code>gl_Position</code> output.  The projection matrix places
     * the far plane at infinity.  This is useful in algorithms like shadow volumes and GPU ray casting with
     * proxy geometry to ensure that triangles are not clipped by the far plane.
     *
     * @example
     * // GLSL declaration
     * uniform mat4 czm_modelViewInfiniteProjection;
     *
     * // Example
     * vec4 gl_Position = czm_modelViewInfiniteProjection * modelPosition;
     *
     * // The above is equivalent to, but more efficient than:
     * gl_Position = czm_infiniteProjection * czm_view * czm_model * modelPosition;
     *
     * @see UniformState#modelViewInfiniteProjection
     * @see czm_model
     * @see czm_view
     * @see czm_infiniteProjection
     * @see czm_modelViewProjection
     */
    czm_modelViewInfiniteProjection: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT4,
      getValue: function (uniformState) {
        return uniformState.modelViewInfiniteProjection;
      },
    }),

    /**
     * An automatic GLSL uniform that indicates if the current camera is orthographic in 3D.
     *
     * @see UniformState#orthographicIn3D
     */
    czm_orthographicIn3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.orthographicIn3D ? 1 : 0;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 normal transformation matrix that
     * transforms normal vectors in model coordinates to eye coordinates.
     * <br /><br />
     * Positions should be transformed to eye coordinates using {@link czm_modelView} and
     * normals should be transformed using <code>czm_normal</code>.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_normal;
     *
     * // Example
     * vec3 eyeNormal = czm_normal * normal;
     *
     * @see UniformState#normal
     * @see czm_inverseNormal
     * @see czm_modelView
     */
    czm_normal: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.normal;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 normal transformation matrix that
     * transforms normal vectors in 3D model coordinates to eye coordinates.
     * In 3D mode, this is identical to
     * {@link czm_normal}, but in 2D and Columbus View it represents the normal transformation
     * matrix as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     * <br /><br />
     * Positions should be transformed to eye coordinates using {@link czm_modelView3D} and
     * normals should be transformed using <code>czm_normal3D</code>.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_normal3D;
     *
     * // Example
     * vec3 eyeNormal = czm_normal3D * normal;
     *
     * @see UniformState#normal3D
     * @see czm_normal
     */
    czm_normal3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.normal3D;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 normal transformation matrix that
     * transforms normal vectors in eye coordinates to model coordinates.  This is
     * the opposite of the transform provided by {@link czm_normal}.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_inverseNormal;
     *
     * // Example
     * vec3 normalMC = czm_inverseNormal * normalEC;
     *
     * @see UniformState#inverseNormal
     * @see czm_normal
     * @see czm_modelView
     * @see czm_inverseView
     */
    czm_inverseNormal: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.inverseNormal;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 normal transformation matrix that
     * transforms normal vectors in eye coordinates to 3D model coordinates.  This is
     * the opposite of the transform provided by {@link czm_normal}.
     * In 3D mode, this is identical to
     * {@link czm_inverseNormal}, but in 2D and Columbus View it represents the inverse normal transformation
     * matrix as if the camera were at an equivalent location in 3D mode.  This is useful for lighting
     * 2D and Columbus View in the same way that 3D is lit.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_inverseNormal3D;
     *
     * // Example
     * vec3 normalMC = czm_inverseNormal3D * normalEC;
     *
     * @see UniformState#inverseNormal3D
     * @see czm_inverseNormal
     */
    czm_inverseNormal3D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.inverseNormal3D;
      },
    }),

    /**
     * An automatic GLSL uniform containing the height in meters of the
     * eye (camera) above or below the ellipsoid.
     *
     * @see UniformState#eyeHeight
     */
    czm_eyeHeight: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.eyeHeight;
      },
    }),

    /**
     * An automatic GLSL uniform containing height (<code>x</code>) and height squared (<code>y</code>)
     * in meters of the eye (camera) above the 2D world plane. This uniform is only valid
     * when the {@link SceneMode} is <code>SCENE2D</code>.
     *
     * @see UniformState#eyeHeight2D
     */
    czm_eyeHeight2D: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC2,
      getValue: function (uniformState) {
        return uniformState.eyeHeight2D;
      },
    }),

    /**
     * An automatic GLSL uniform containing the near distance (<code>x</code>) and the far distance (<code>y</code>)
     * of the frustum defined by the camera.  This is the largest possible frustum, not an individual
     * frustum used for multi-frustum rendering.
     *
     * @example
     * // GLSL declaration
     * uniform vec2 czm_entireFrustum;
     *
     * // Example
     * float frustumLength = czm_entireFrustum.y - czm_entireFrustum.x;
     *
     * @see UniformState#entireFrustum
     * @see czm_currentFrustum
     */
    czm_entireFrustum: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC2,
      getValue: function (uniformState) {
        return uniformState.entireFrustum;
      },
    }),

    /**
     * An automatic GLSL uniform containing the near distance (<code>x</code>) and the far distance (<code>y</code>)
     * of the frustum defined by the camera.  This is the individual
     * frustum used for multi-frustum rendering.
     *
     * @example
     * // GLSL declaration
     * uniform vec2 czm_currentFrustum;
     *
     * // Example
     * float frustumLength = czm_currentFrustum.y - czm_currentFrustum.x;
     *
     * @see UniformState#currentFrustum
     * @see czm_entireFrustum
     */
    czm_currentFrustum: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC2,
      getValue: function (uniformState) {
        return uniformState.currentFrustum;
      },
    }),

    /**
     * The distances to the frustum planes. The top, bottom, left and right distances are
     * the x, y, z, and w components, respectively.
     */
    czm_frustumPlanes: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC4,
      getValue: function (uniformState) {
        return uniformState.frustumPlanes;
      },
    }),

    /**
     * Gets the far plane's distance from the near plane, plus 1.0.
     */
    czm_farDepthFromNearPlusOne: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.farDepthFromNearPlusOne;
      },
    }),

    /**
     * Gets the log2 of {@link AutomaticUniforms#czm_farDepthFromNearPlusOne}.
     */
    czm_log2FarDepthFromNearPlusOne: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.log2FarDepthFromNearPlusOne;
      },
    }),

    /**
     * Gets 1.0 divided by {@link AutomaticUniforms#czm_log2FarDepthFromNearPlusOne}.
     */
    czm_oneOverLog2FarDepthFromNearPlusOne: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.oneOverLog2FarDepthFromNearPlusOne;
      },
    }),

    /**
     * An automatic GLSL uniform representing the sun position in world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_sunPositionWC;
     *
     * @see UniformState#sunPositionWC
     * @see czm_sunPositionColumbusView
     * @see czm_sunDirectionWC
     */
    czm_sunPositionWC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.sunPositionWC;
      },
    }),

    /**
     * An automatic GLSL uniform representing the sun position in Columbus view world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_sunPositionColumbusView;
     *
     * @see UniformState#sunPositionColumbusView
     * @see czm_sunPositionWC
     */
    czm_sunPositionColumbusView: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.sunPositionColumbusView;
      },
    }),

    /**
     * An automatic GLSL uniform representing the normalized direction to the sun in eye coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_sunDirectionEC;
     *
     * // Example
     * float diffuse = max(dot(czm_sunDirectionEC, normalEC), 0.0);
     *
     * @see UniformState#sunDirectionEC
     * @see czm_moonDirectionEC
     * @see czm_sunDirectionWC
     */
    czm_sunDirectionEC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.sunDirectionEC;
      },
    }),

    /**
     * An automatic GLSL uniform representing the normalized direction to the sun in world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_sunDirectionWC;
     *
     * // Example
     * float diffuse = max(dot(czm_sunDirectionWC, normalWC), 0.0);
     *
     * @see UniformState#sunDirectionWC
     * @see czm_sunPositionWC
     * @see czm_sunDirectionEC
     */
    czm_sunDirectionWC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.sunDirectionWC;
      },
    }),

    /**
     * An automatic GLSL uniform representing the normalized direction to the moon in eye coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_moonDirectionEC;
     *
     * // Example
     * float diffuse = max(dot(czm_moonDirectionEC, normalEC), 0.0);
     *
     * @see UniformState#moonDirectionEC
     * @see czm_sunDirectionEC
     */
    czm_moonDirectionEC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.moonDirectionEC;
      },
    }),

    /**
     * An automatic GLSL uniform representing the normalized direction to the scene's light source in eye coordinates.
     * This is commonly used for directional lighting computations.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_lightDirectionEC;
     *
     * // Example
     * float diffuse = max(dot(czm_lightDirectionEC, normalEC), 0.0);
     *
     * @see UniformState#lightDirectionEC
     * @see czm_lightDirectionWC
     */
    czm_lightDirectionEC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.lightDirectionEC;
      },
    }),

    /**
     * An automatic GLSL uniform representing the normalized direction to the scene's light source in world coordinates.
     * This is commonly used for directional lighting computations.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_lightDirectionWC;
     *
     * // Example
     * float diffuse = max(dot(czm_lightDirectionWC, normalWC), 0.0);
     *
     * @see UniformState#lightDirectionWC
     * @see czm_lightDirectionEC
     */
    czm_lightDirectionWC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.lightDirectionWC;
      },
    }),

    /**
     * An automatic GLSL uniform that represents the color of light emitted by the scene's light source. This
     * is equivalent to the light color multiplied by the light intensity limited to a maximum luminance of 1.0
     * suitable for non-HDR lighting.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_lightColor;
     *
     * // Example
     * vec3 diffuseColor = czm_lightColor * max(dot(czm_lightDirectionWC, normalWC), 0.0);
     *
     * @see UniformState#lightColor
     * @see czm_lightColorHdr
     */
    czm_lightColor: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.lightColor;
      },
    }),

    /**
     * An automatic GLSL uniform that represents the high dynamic range color of light emitted by the scene's light
     * source. This is equivalent to the light color multiplied by the light intensity suitable for HDR lighting.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_lightColorHdr;
     *
     * // Example
     * vec3 diffuseColor = czm_lightColorHdr * max(dot(czm_lightDirectionWC, normalWC), 0.0);
     *
     * @see UniformState#lightColorHdr
     * @see czm_lightColor
     */
    czm_lightColorHdr: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.lightColorHdr;
      },
    }),

    /**
     * An automatic GLSL uniform representing the high bits of the camera position in model
     * coordinates.  This is used for GPU RTE to eliminate jittering artifacts when rendering
     * as described in {@link http://help.agi.com/AGIComponents/html/BlogPrecisionsPrecisions.htm|Precisions, Precisions}.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_encodedCameraPositionMCHigh;
     *
     * @see czm_encodedCameraPositionMCLow
     * @see czm_modelViewRelativeToEye
     * @see czm_modelViewProjectionRelativeToEye
     */
    czm_encodedCameraPositionMCHigh: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.encodedCameraPositionMCHigh;
      },
    }),

    /**
     * An automatic GLSL uniform representing the low bits of the camera position in model
     * coordinates.  This is used for GPU RTE to eliminate jittering artifacts when rendering
     * as described in {@linkhttp://help.agi.com/AGIComponents/html/BlogPrecisionsPrecisions.htm|Precisions, Precisions}.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_encodedCameraPositionMCLow;
     *
     * @see czm_encodedCameraPositionMCHigh
     * @see czm_modelViewRelativeToEye
     * @see czm_modelViewProjectionRelativeToEye
     */
    czm_encodedCameraPositionMCLow: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.encodedCameraPositionMCLow;
      },
    }),

    /**
     * An automatic GLSL uniform representing the position of the viewer (camera) in world coordinates.
     *
     * @example
     * // GLSL declaration
     * uniform vec3 czm_viewerPositionWC;
     */
    czm_viewerPositionWC: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return Matrix4.getTranslation(
          uniformState.inverseView,
          viewerPositionWCScratch
        );
      },
    }),

    /**
     * An automatic GLSL uniform representing the frame number. This uniform is automatically incremented
     * every frame.
     *
     * @example
     * // GLSL declaration
     * uniform float czm_frameNumber;
     */
    czm_frameNumber: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.frameState.frameNumber;
      },
    }),

    /**
     * An automatic GLSL uniform representing the current morph transition time between
     * 2D/Columbus View and 3D, with 0.0 being 2D or Columbus View and 1.0 being 3D.
     *
     * @example
     * // GLSL declaration
     * uniform float czm_morphTime;
     *
     * // Example
     * vec4 p = czm_columbusViewMorph(position2D, position3D, czm_morphTime);
     */
    czm_morphTime: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.frameState.morphTime;
      },
    }),

    /**
     * An automatic GLSL uniform representing the current {@link SceneMode}, expressed
     * as a float.
     *
     * @example
     * // GLSL declaration
     * uniform float czm_sceneMode;
     *
     * // Example
     * if (czm_sceneMode == czm_sceneMode2D)
     * {
     *     eyeHeightSq = czm_eyeHeight2D.y;
     * }
     *
     * @see czm_sceneMode2D
     * @see czm_sceneModeColumbusView
     * @see czm_sceneMode3D
     * @see czm_sceneModeMorphing
     */
    czm_sceneMode: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.frameState.mode;
      },
    }),

    /**
     * An automatic GLSL uniform representing the current rendering pass.
     *
     * @example
     * // GLSL declaration
     * uniform float czm_pass;
     *
     * // Example
     * if ((czm_pass == czm_passTranslucent) && isOpaque())
     * {
     *     gl_Position *= 0.0; // Cull opaque geometry in the translucent pass
     * }
     */
    czm_pass: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.pass;
      },
    }),

    /**
     * An automatic GLSL uniform representing the current scene background color.
     *
     * @example
     * // GLSL declaration
     * uniform vec4 czm_backgroundColor;
     *
     * // Example: If the given color's RGB matches the background color, invert it.
     * vec4 adjustColorForContrast(vec4 color)
     * {
     *     if (czm_backgroundColor.rgb == color.rgb)
     *     {
     *         color.rgb = vec3(1.0) - color.rgb;
     *     }
     *
     *     return color;
     * }
     */
    czm_backgroundColor: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC4,
      getValue: function (uniformState) {
        return uniformState.backgroundColor;
      },
    }),

    /**
     * An automatic GLSL uniform containing the BRDF look up texture used for image-based lighting computations.
     *
     * @example
     * // GLSL declaration
     * uniform sampler2D czm_brdfLut;
     *
     * // Example: For a given roughness and NdotV value, find the material's BRDF information in the red and green channels
     * float roughness = 0.5;
     * float NdotV = dot(normal, view);
     * vec2 brdfLut = texture2D(czm_brdfLut, vec2(NdotV, 1.0 - roughness)).rg;
     */
    czm_brdfLut: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.SAMPLER_2D,
      getValue: function (uniformState) {
        return uniformState.brdfLut;
      },
    }),

    /**
     * An automatic GLSL uniform containing the environment map used within the scene.
     *
     * @example
     * // GLSL declaration
     * uniform samplerCube czm_environmentMap;
     *
     * // Example: Create a perfect reflection of the environment map on a  model
     * float reflected = reflect(view, normal);
     * vec4 reflectedColor = textureCube(czm_environmentMap, reflected);
     */
    czm_environmentMap: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.SAMPLER_CUBE,
      getValue: function (uniformState) {
        return uniformState.environmentMap;
      },
    }),

    /**
     * An automatic GLSL uniform containing the specular environment map atlas used within the scene.
     *
     * @example
     * // GLSL declaration
     * uniform sampler2D czm_specularEnvironmentMaps;
     */
    czm_specularEnvironmentMaps: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.SAMPLER_2D,
      getValue: function (uniformState) {
        return uniformState.specularEnvironmentMaps;
      },
    }),

    /**
     * An automatic GLSL uniform containing the size of the specular environment map atlas used within the scene.
     *
     * @example
     * // GLSL declaration
     * uniform vec2 czm_specularEnvironmentMapSize;
     */
    czm_specularEnvironmentMapSize: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC2,
      getValue: function (uniformState) {
        return uniformState.specularEnvironmentMapsDimensions;
      },
    }),

    /**
     * An automatic GLSL uniform containing the maximum level-of-detail of the specular environment map atlas used within the scene.
     *
     * @example
     * // GLSL declaration
     * uniform float czm_specularEnvironmentMapsMaximumLOD;
     */
    czm_specularEnvironmentMapsMaximumLOD: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.specularEnvironmentMapsMaximumLOD;
      },
    }),

    /**
     * An automatic GLSL uniform containing the spherical harmonic coefficients used within the scene.
     *
     * @example
     * // GLSL declaration
     * uniform vec3[9] czm_sphericalHarmonicCoefficients;
     */
    czm_sphericalHarmonicCoefficients: new AutomaticUniform({
      size: 9,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.sphericalHarmonicCoefficients;
      },
    }),

    /**
     * An automatic GLSL uniform representing a 3x3 rotation matrix that transforms
     * from True Equator Mean Equinox (TEME) axes to the pseudo-fixed axes at the current scene time.
     *
     * @example
     * // GLSL declaration
     * uniform mat3 czm_temeToPseudoFixed;
     *
     * // Example
     * vec3 pseudoFixed = czm_temeToPseudoFixed * teme;
     *
     * @see UniformState#temeToPseudoFixedMatrix
     * @see Transforms.computeTemeToPseudoFixedMatrix
     */
    czm_temeToPseudoFixed: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_MAT3,
      getValue: function (uniformState) {
        return uniformState.temeToPseudoFixedMatrix;
      },
    }),

    /**
     * An automatic GLSL uniform representing the ratio of canvas coordinate space to canvas pixel space.
     *
     * @example
     * uniform float czm_pixelRatio;
     */
    czm_pixelRatio: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.pixelRatio;
      },
    }),

    /**
     * An automatic GLSL uniform scalar used to mix a color with the fog color based on the distance to the camera.
     *
     * @see czm_fog
     */
    czm_fogDensity: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.fogDensity;
      },
    }),

    /**
     * An automatic GLSL uniform representing the splitter position to use when rendering imagery layers with a splitter.
     * This will be in pixel coordinates relative to the canvas.
     *
     * @example
     * // GLSL declaration
     * uniform float czm_imagerySplitPosition;
     */
    czm_imagerySplitPosition: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.imagerySplitPosition;
      },
    }),

    /**
     * An automatic GLSL uniform scalar representing the geometric tolerance per meter
     */
    czm_geometricToleranceOverMeter: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.geometricToleranceOverMeter;
      },
    }),

    /**
     * An automatic GLSL uniform representing the distance from the camera at which to disable the depth test of billboards, labels and points
     * to, for example, prevent clipping against terrain. When set to zero, the depth test should always be applied. When less than zero,
     * the depth test should never be applied.
     */
    czm_minimumDisableDepthTestDistance: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.minimumDisableDepthTestDistance;
      },
    }),

    /**
     * An automatic GLSL uniform that will be the highlight color of unclassified 3D Tiles.
     */
    czm_invertClassificationColor: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC4,
      getValue: function (uniformState) {
        return uniformState.invertClassificationColor;
      },
    }),

    /**
     * An automatic GLSL uniform that is used for gamma correction.
     */
    czm_gamma: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT,
      getValue: function (uniformState) {
        return uniformState.gamma;
      },
    }),

    /**
     * An automatic GLSL uniform that stores the ellipsoid radii.
     */
    czm_ellipsoidRadii: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.ellipsoid.radii;
      },
    }),

    /**
     * An automatic GLSL uniform that stores the ellipsoid inverse radii.
     */
    czm_ellipsoidInverseRadii: new AutomaticUniform({
      size: 1,
      datatype: WebGLConstants$1.FLOAT_VEC3,
      getValue: function (uniformState) {
        return uniformState.ellipsoid.oneOverRadii;
      },
    }),
  };

  /**
   * @private
   * @constructor
   */
  function createUniform$1(gl, activeUniform, uniformName, location) {
    switch (activeUniform.type) {
      case gl.FLOAT:
        return new UniformFloat(gl, activeUniform, uniformName, location);
      case gl.FLOAT_VEC2:
        return new UniformFloatVec2(gl, activeUniform, uniformName, location);
      case gl.FLOAT_VEC3:
        return new UniformFloatVec3(gl, activeUniform, uniformName, location);
      case gl.FLOAT_VEC4:
        return new UniformFloatVec4(gl, activeUniform, uniformName, location);
      case gl.SAMPLER_2D:
      case gl.SAMPLER_CUBE:
        return new UniformSampler(gl, activeUniform, uniformName, location);
      case gl.INT:
      case gl.BOOL:
        return new UniformInt(gl, activeUniform, uniformName, location);
      case gl.INT_VEC2:
      case gl.BOOL_VEC2:
        return new UniformIntVec2(gl, activeUniform, uniformName, location);
      case gl.INT_VEC3:
      case gl.BOOL_VEC3:
        return new UniformIntVec3(gl, activeUniform, uniformName, location);
      case gl.INT_VEC4:
      case gl.BOOL_VEC4:
        return new UniformIntVec4(gl, activeUniform, uniformName, location);
      case gl.FLOAT_MAT2:
        return new UniformMat2(gl, activeUniform, uniformName, location);
      case gl.FLOAT_MAT3:
        return new UniformMat3(gl, activeUniform, uniformName, location);
      case gl.FLOAT_MAT4:
        return new UniformMat4(gl, activeUniform, uniformName, location);
      default:
        throw new RuntimeError(
          "Unrecognized uniform type: " +
            activeUniform.type +
            ' for uniform "' +
            uniformName +
            '".'
        );
    }
  }

  /**
   * @private
   * @constructor
   */
  function UniformFloat(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = 0.0;

    this._gl = gl;
    this._location = location;
  }

  UniformFloat.prototype.set = function () {
    if (this.value !== this._value) {
      this._value = this.value;
      this._gl.uniform1f(this._location, this.value);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformFloatVec2(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Cartesian2();

    this._gl = gl;
    this._location = location;
  }

  UniformFloatVec2.prototype.set = function () {
    var v = this.value;
    if (!Cartesian2.equals(v, this._value)) {
      Cartesian2.clone(v, this._value);
      this._gl.uniform2f(this._location, v.x, v.y);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformFloatVec3(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = undefined;

    this._gl = gl;
    this._location = location;
  }

  UniformFloatVec3.prototype.set = function () {
    var v = this.value;

    if (defined(v.red)) {
      if (!Color.equals(v, this._value)) {
        this._value = Color.clone(v, this._value);
        this._gl.uniform3f(this._location, v.red, v.green, v.blue);
      }
    } else if (defined(v.x)) {
      if (!Cartesian3.equals(v, this._value)) {
        this._value = Cartesian3.clone(v, this._value);
        this._gl.uniform3f(this._location, v.x, v.y, v.z);
      }
    } else {
      //>>includeStart('debug', pragmas.debug);
      throw new DeveloperError(
        'Invalid vec3 value for uniform "' + this.name + '".'
      );
      //>>includeEnd('debug');
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformFloatVec4(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = undefined;

    this._gl = gl;
    this._location = location;
  }

  UniformFloatVec4.prototype.set = function () {
    var v = this.value;

    if (defined(v.red)) {
      if (!Color.equals(v, this._value)) {
        this._value = Color.clone(v, this._value);
        this._gl.uniform4f(this._location, v.red, v.green, v.blue, v.alpha);
      }
    } else if (defined(v.x)) {
      if (!Cartesian4.equals(v, this._value)) {
        this._value = Cartesian4.clone(v, this._value);
        this._gl.uniform4f(this._location, v.x, v.y, v.z, v.w);
      }
    } else {
      //>>includeStart('debug', pragmas.debug);
      throw new DeveloperError(
        'Invalid vec4 value for uniform "' + this.name + '".'
      );
      //>>includeEnd('debug');
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformSampler(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;

    this._gl = gl;
    this._location = location;

    this.textureUnitIndex = undefined;
  }

  UniformSampler.prototype.set = function () {
    var gl = this._gl;
    gl.activeTexture(gl.TEXTURE0 + this.textureUnitIndex);

    var v = this.value;
    gl.bindTexture(v._target, v._texture);
  };

  UniformSampler.prototype._setSampler = function (textureUnitIndex) {
    this.textureUnitIndex = textureUnitIndex;
    this._gl.uniform1i(this._location, textureUnitIndex);
    return textureUnitIndex + 1;
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformInt(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = 0.0;

    this._gl = gl;
    this._location = location;
  }

  UniformInt.prototype.set = function () {
    if (this.value !== this._value) {
      this._value = this.value;
      this._gl.uniform1i(this._location, this.value);
    }
  };

  ///////////////////////////////////////////////////////////////////////////
  /**
   * @private
   * @constructor
   */
  function UniformIntVec2(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Cartesian2();

    this._gl = gl;
    this._location = location;
  }

  UniformIntVec2.prototype.set = function () {
    var v = this.value;
    if (!Cartesian2.equals(v, this._value)) {
      Cartesian2.clone(v, this._value);
      this._gl.uniform2i(this._location, v.x, v.y);
    }
  };

  ///////////////////////////////////////////////////////////////////////////
  /**
   * @private
   * @constructor
   */
  function UniformIntVec3(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Cartesian3();

    this._gl = gl;
    this._location = location;
  }

  UniformIntVec3.prototype.set = function () {
    var v = this.value;
    if (!Cartesian3.equals(v, this._value)) {
      Cartesian3.clone(v, this._value);
      this._gl.uniform3i(this._location, v.x, v.y, v.z);
    }
  };

  ///////////////////////////////////////////////////////////////////////////
  /**
   * @private
   * @constructor
   */
  function UniformIntVec4(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Cartesian4();

    this._gl = gl;
    this._location = location;
  }

  UniformIntVec4.prototype.set = function () {
    var v = this.value;
    if (!Cartesian4.equals(v, this._value)) {
      Cartesian4.clone(v, this._value);
      this._gl.uniform4i(this._location, v.x, v.y, v.z, v.w);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  var scratchUniformArray = new Float32Array(4);
  /**
   * @private
   * @constructor
   */
  function UniformMat2(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Matrix2();

    this._gl = gl;
    this._location = location;
  }

  UniformMat2.prototype.set = function () {
    if (!Matrix2.equalsArray(this.value, this._value, 0)) {
      Matrix2.clone(this.value, this._value);

      var array = Matrix2.toArray(this.value, scratchUniformArray);
      this._gl.uniformMatrix2fv(this._location, false, array);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  var scratchMat3Array = new Float32Array(9);
  /**
   * @private
   * @constructor
   */
  function UniformMat3(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Matrix3();

    this._gl = gl;
    this._location = location;
  }

  UniformMat3.prototype.set = function () {
    if (!Matrix3.equalsArray(this.value, this._value, 0)) {
      Matrix3.clone(this.value, this._value);

      var array = Matrix3.toArray(this.value, scratchMat3Array);
      this._gl.uniformMatrix3fv(this._location, false, array);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  var scratchMat4Array = new Float32Array(16);
  /**
   * @private
   * @constructor
   */
  function UniformMat4(gl, activeUniform, uniformName, location) {
    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = undefined;
    this._value = new Matrix4();

    this._gl = gl;
    this._location = location;
  }

  UniformMat4.prototype.set = function () {
    if (!Matrix4.equalsArray(this.value, this._value, 0)) {
      Matrix4.clone(this.value, this._value);

      var array = Matrix4.toArray(this.value, scratchMat4Array);
      this._gl.uniformMatrix4fv(this._location, false, array);
    }
  };

  /**
   * @private
   * @constructor
   */
  function createUniformArray(gl, activeUniform, uniformName, locations) {
    switch (activeUniform.type) {
      case gl.FLOAT:
        return new UniformArrayFloat(gl, activeUniform, uniformName, locations);
      case gl.FLOAT_VEC2:
        return new UniformArrayFloatVec2(
          gl,
          activeUniform,
          uniformName,
          locations
        );
      case gl.FLOAT_VEC3:
        return new UniformArrayFloatVec3(
          gl,
          activeUniform,
          uniformName,
          locations
        );
      case gl.FLOAT_VEC4:
        return new UniformArrayFloatVec4(
          gl,
          activeUniform,
          uniformName,
          locations
        );
      case gl.SAMPLER_2D:
      case gl.SAMPLER_CUBE:
        return new UniformArraySampler(gl, activeUniform, uniformName, locations);
      case gl.INT:
      case gl.BOOL:
        return new UniformArrayInt(gl, activeUniform, uniformName, locations);
      case gl.INT_VEC2:
      case gl.BOOL_VEC2:
        return new UniformArrayIntVec2(gl, activeUniform, uniformName, locations);
      case gl.INT_VEC3:
      case gl.BOOL_VEC3:
        return new UniformArrayIntVec3(gl, activeUniform, uniformName, locations);
      case gl.INT_VEC4:
      case gl.BOOL_VEC4:
        return new UniformArrayIntVec4(gl, activeUniform, uniformName, locations);
      case gl.FLOAT_MAT2:
        return new UniformArrayMat2(gl, activeUniform, uniformName, locations);
      case gl.FLOAT_MAT3:
        return new UniformArrayMat3(gl, activeUniform, uniformName, locations);
      case gl.FLOAT_MAT4:
        return new UniformArrayMat4(gl, activeUniform, uniformName, locations);
      default:
        throw new RuntimeError(
          "Unrecognized uniform type: " +
            activeUniform.type +
            ' for uniform "' +
            uniformName +
            '".'
        );
    }
  }

  /**
   * @private
   * @constructor
   */
  function UniformArrayFloat(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayFloat.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (v !== arraybuffer[i]) {
        arraybuffer[i] = v;
        changed = true;
      }
    }

    if (changed) {
      this._gl.uniform1fv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayFloatVec2(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length * 2);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayFloatVec2.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Cartesian2.equalsArray(v, arraybuffer, j)) {
        Cartesian2.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 2;
    }

    if (changed) {
      this._gl.uniform2fv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayFloatVec3(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length * 3);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayFloatVec3.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (defined(v.red)) {
        if (
          v.red !== arraybuffer[j] ||
          v.green !== arraybuffer[j + 1] ||
          v.blue !== arraybuffer[j + 2]
        ) {
          arraybuffer[j] = v.red;
          arraybuffer[j + 1] = v.green;
          arraybuffer[j + 2] = v.blue;
          changed = true;
        }
      } else if (defined(v.x)) {
        if (!Cartesian3.equalsArray(v, arraybuffer, j)) {
          Cartesian3.pack(v, arraybuffer, j);
          changed = true;
        }
      } else {
        //>>includeStart('debug', pragmas.debug);
        throw new DeveloperError("Invalid vec3 value.");
        //>>includeEnd('debug');
      }

      j += 3;
    }

    if (changed) {
      this._gl.uniform3fv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayFloatVec4(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length * 4);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayFloatVec4.prototype.set = function () {
    // PERFORMANCE_IDEA: if it is a common case that only a few elements
    // in a uniform array change, we could use heuristics to determine
    // when it is better to call uniform4f for each element that changed
    // vs. call uniform4fv once to set the entire array.  This applies
    // to all uniform array types, not just vec4.  We might not care
    // once we have uniform buffers since that will be the fast path.

    // PERFORMANCE_IDEA: Micro-optimization (I bet it works though):
    // As soon as changed is true, break into a separate loop that
    // does the copy without the equals check.

    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (defined(v.red)) {
        if (!Color.equalsArray(v, arraybuffer, j)) {
          Color.pack(v, arraybuffer, j);
          changed = true;
        }
      } else if (defined(v.x)) {
        if (!Cartesian4.equalsArray(v, arraybuffer, j)) {
          Cartesian4.pack(v, arraybuffer, j);
          changed = true;
        }
      } else {
        //>>includeStart('debug', pragmas.debug);
        throw new DeveloperError("Invalid vec4 value.");
        //>>includeEnd('debug');
      }

      j += 4;
    }

    if (changed) {
      this._gl.uniform4fv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArraySampler(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length);

    this._gl = gl;
    this._locations = locations;

    this.textureUnitIndex = undefined;
  }

  UniformArraySampler.prototype.set = function () {
    var gl = this._gl;
    var textureUnitIndex = gl.TEXTURE0 + this.textureUnitIndex;

    var value = this.value;
    var length = value.length;
    for (var i = 0; i < length; ++i) {
      var v = value[i];
      gl.activeTexture(textureUnitIndex + i);
      gl.bindTexture(v._target, v._texture);
    }
  };

  UniformArraySampler.prototype._setSampler = function (textureUnitIndex) {
    this.textureUnitIndex = textureUnitIndex;

    var locations = this._locations;
    var length = locations.length;
    for (var i = 0; i < length; ++i) {
      var index = textureUnitIndex + i;
      this._gl.uniform1i(locations[i], index);
    }

    return textureUnitIndex + length;
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayInt(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Int32Array(length);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayInt.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (v !== arraybuffer[i]) {
        arraybuffer[i] = v;
        changed = true;
      }
    }

    if (changed) {
      this._gl.uniform1iv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayIntVec2(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Int32Array(length * 2);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayIntVec2.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Cartesian2.equalsArray(v, arraybuffer, j)) {
        Cartesian2.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 2;
    }

    if (changed) {
      this._gl.uniform2iv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayIntVec3(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Int32Array(length * 3);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayIntVec3.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Cartesian3.equalsArray(v, arraybuffer, j)) {
        Cartesian3.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 3;
    }

    if (changed) {
      this._gl.uniform3iv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayIntVec4(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Int32Array(length * 4);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayIntVec4.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Cartesian4.equalsArray(v, arraybuffer, j)) {
        Cartesian4.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 4;
    }

    if (changed) {
      this._gl.uniform4iv(this._location, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayMat2(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length * 4);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayMat2.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Matrix2.equalsArray(v, arraybuffer, j)) {
        Matrix2.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 4;
    }

    if (changed) {
      this._gl.uniformMatrix2fv(this._location, false, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayMat3(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length * 9);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayMat3.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Matrix3.equalsArray(v, arraybuffer, j)) {
        Matrix3.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 9;
    }

    if (changed) {
      this._gl.uniformMatrix3fv(this._location, false, arraybuffer);
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  /**
   * @private
   * @constructor
   */
  function UniformArrayMat4(gl, activeUniform, uniformName, locations) {
    var length = locations.length;

    /**
     * @type {String}
     * @readonly
     */
    this.name = uniformName;

    this.value = new Array(length);
    this._value = new Float32Array(length * 16);

    this._gl = gl;
    this._location = locations[0];
  }

  UniformArrayMat4.prototype.set = function () {
    var value = this.value;
    var length = value.length;
    var arraybuffer = this._value;
    var changed = false;
    var j = 0;

    for (var i = 0; i < length; ++i) {
      var v = value[i];

      if (!Matrix4.equalsArray(v, arraybuffer, j)) {
        Matrix4.pack(v, arraybuffer, j);
        changed = true;
      }
      j += 16;
    }

    if (changed) {
      this._gl.uniformMatrix4fv(this._location, false, arraybuffer);
    }
  };

  var nextShaderProgramId = 0;

  /**
   * @private
   */
  function ShaderProgram(options) {
    var vertexShaderText = options.vertexShaderText;
    var fragmentShaderText = options.fragmentShaderText;

    if (typeof spector !== "undefined") {
      // The #line statements common in Cesium shaders interfere with the ability of the
      // SpectorJS to show errors on the correct line. So remove them when SpectorJS
      // is active.
      vertexShaderText = vertexShaderText.replace(/^#line/gm, "//#line");
      fragmentShaderText = fragmentShaderText.replace(/^#line/gm, "//#line");
    }

    var modifiedFS = handleUniformPrecisionMismatches(
      vertexShaderText,
      fragmentShaderText
    );

    this._gl = options.gl;
    this._logShaderCompilation = options.logShaderCompilation;
    this._debugShaders = options.debugShaders;
    this._attributeLocations = options.attributeLocations;

    this._program = undefined;
    this._numberOfVertexAttributes = undefined;
    this._vertexAttributes = undefined;
    this._uniformsByName = undefined;
    this._uniforms = undefined;
    this._automaticUniforms = undefined;
    this._manualUniforms = undefined;
    this._duplicateUniformNames = modifiedFS.duplicateUniformNames;
    this._cachedShader = undefined; // Used by ShaderCache

    /**
     * @private
     */
    this.maximumTextureUnitIndex = undefined;

    this._vertexShaderSource = options.vertexShaderSource;
    this._vertexShaderText = options.vertexShaderText;
    this._fragmentShaderSource = options.fragmentShaderSource;
    this._fragmentShaderText = modifiedFS.fragmentShaderText;

    /**
     * @private
     */
    this.id = nextShaderProgramId++;
  }

  ShaderProgram.fromCache = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    return options.context.shaderCache.getShaderProgram(options);
  };

  ShaderProgram.replaceCache = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    return options.context.shaderCache.replaceShaderProgram(options);
  };

  Object.defineProperties(ShaderProgram.prototype, {
    /**
     * GLSL source for the shader program's vertex shader.
     * @memberof ShaderProgram.prototype
     *
     * @type {ShaderSource}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },
    /**
     * GLSL source for the shader program's fragment shader.
     * @memberof ShaderProgram.prototype
     *
     * @type {ShaderSource}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },
    vertexAttributes: {
      get: function () {
        initialize$1(this);
        return this._vertexAttributes;
      },
    },
    numberOfVertexAttributes: {
      get: function () {
        initialize$1(this);
        return this._numberOfVertexAttributes;
      },
    },
    allUniforms: {
      get: function () {
        initialize$1(this);
        return this._uniformsByName;
      },
    },
  });

  function extractUniforms(shaderText) {
    var uniformNames = [];
    var uniformLines = shaderText.match(/uniform.*?(?![^{]*})(?=[=\[;])/g);
    if (defined(uniformLines)) {
      var len = uniformLines.length;
      for (var i = 0; i < len; i++) {
        var line = uniformLines[i].trim();
        var name = line.slice(line.lastIndexOf(" ") + 1);
        uniformNames.push(name);
      }
    }
    return uniformNames;
  }

  function handleUniformPrecisionMismatches(
    vertexShaderText,
    fragmentShaderText
  ) {
    // If a uniform exists in both the vertex and fragment shader but with different precision qualifiers,
    // give the fragment shader uniform a different name. This fixes shader compilation errors on devices
    // that only support mediump in the fragment shader.
    var duplicateUniformNames = {};

    if (!ContextLimits.highpFloatSupported || !ContextLimits.highpIntSupported) {
      var i, j;
      var uniformName;
      var duplicateName;
      var vertexShaderUniforms = extractUniforms(vertexShaderText);
      var fragmentShaderUniforms = extractUniforms(fragmentShaderText);
      var vertexUniformsCount = vertexShaderUniforms.length;
      var fragmentUniformsCount = fragmentShaderUniforms.length;

      for (i = 0; i < vertexUniformsCount; i++) {
        for (j = 0; j < fragmentUniformsCount; j++) {
          if (vertexShaderUniforms[i] === fragmentShaderUniforms[j]) {
            uniformName = vertexShaderUniforms[i];
            duplicateName = "czm_mediump_" + uniformName;
            // Update fragmentShaderText with renamed uniforms
            var re = new RegExp(uniformName + "\\b", "g");
            fragmentShaderText = fragmentShaderText.replace(re, duplicateName);
            duplicateUniformNames[duplicateName] = uniformName;
          }
        }
      }
    }

    return {
      fragmentShaderText: fragmentShaderText,
      duplicateUniformNames: duplicateUniformNames,
    };
  }

  var consolePrefix = "[Cesium WebGL] ";

  function createAndLinkProgram(gl, shader) {
    var vsSource = shader._vertexShaderText;
    var fsSource = shader._fragmentShaderText;

    var vertexShader = gl.createShader(gl.VERTEX_SHADER);
    gl.shaderSource(vertexShader, vsSource);
    gl.compileShader(vertexShader);

    var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
    gl.shaderSource(fragmentShader, fsSource);
    gl.compileShader(fragmentShader);

    var program = gl.createProgram();
    gl.attachShader(program, vertexShader);
    gl.attachShader(program, fragmentShader);

    gl.deleteShader(vertexShader);
    gl.deleteShader(fragmentShader);

    var attributeLocations = shader._attributeLocations;
    if (defined(attributeLocations)) {
      for (var attribute in attributeLocations) {
        if (attributeLocations.hasOwnProperty(attribute)) {
          gl.bindAttribLocation(
            program,
            attributeLocations[attribute],
            attribute
          );
        }
      }
    }

    gl.linkProgram(program);

    var log;
    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
      var debugShaders = shader._debugShaders;

      // For performance, only check compile errors if there is a linker error.
      if (!gl.getShaderParameter(fragmentShader, gl.COMPILE_STATUS)) {
        log = gl.getShaderInfoLog(fragmentShader);
        console.error(consolePrefix + "Fragment shader compile log: " + log);
        if (defined(debugShaders)) {
          var fragmentSourceTranslation = debugShaders.getTranslatedShaderSource(
            fragmentShader
          );
          if (fragmentSourceTranslation !== "") {
            console.error(
              consolePrefix +
                "Translated fragment shader source:\n" +
                fragmentSourceTranslation
            );
          } else {
            console.error(consolePrefix + "Fragment shader translation failed.");
          }
        }

        gl.deleteProgram(program);
        throw new RuntimeError(
          "Fragment shader failed to compile.  Compile log: " + log
        );
      }

      if (!gl.getShaderParameter(vertexShader, gl.COMPILE_STATUS)) {
        log = gl.getShaderInfoLog(vertexShader);
        console.error(consolePrefix + "Vertex shader compile log: " + log);
        if (defined(debugShaders)) {
          var vertexSourceTranslation = debugShaders.getTranslatedShaderSource(
            vertexShader
          );
          if (vertexSourceTranslation !== "") {
            console.error(
              consolePrefix +
                "Translated vertex shader source:\n" +
                vertexSourceTranslation
            );
          } else {
            console.error(consolePrefix + "Vertex shader translation failed.");
          }
        }

        gl.deleteProgram(program);
        throw new RuntimeError(
          "Vertex shader failed to compile.  Compile log: " + log
        );
      }

      log = gl.getProgramInfoLog(program);
      console.error(consolePrefix + "Shader program link log: " + log);
      if (defined(debugShaders)) {
        console.error(
          consolePrefix +
            "Translated vertex shader source:\n" +
            debugShaders.getTranslatedShaderSource(vertexShader)
        );
        console.error(
          consolePrefix +
            "Translated fragment shader source:\n" +
            debugShaders.getTranslatedShaderSource(fragmentShader)
        );
      }

      gl.deleteProgram(program);
      throw new RuntimeError("Program failed to link.  Link log: " + log);
    }

    var logShaderCompilation = shader._logShaderCompilation;

    if (logShaderCompilation) {
      log = gl.getShaderInfoLog(vertexShader);
      if (defined(log) && log.length > 0) {
        console.log(consolePrefix + "Vertex shader compile log: " + log);
      }
    }

    if (logShaderCompilation) {
      log = gl.getShaderInfoLog(fragmentShader);
      if (defined(log) && log.length > 0) {
        console.log(consolePrefix + "Fragment shader compile log: " + log);
      }
    }

    if (logShaderCompilation) {
      log = gl.getProgramInfoLog(program);
      if (defined(log) && log.length > 0) {
        console.log(consolePrefix + "Shader program link log: " + log);
      }
    }

    return program;
  }

  function findVertexAttributes(gl, program, numberOfAttributes) {
    var attributes = {};
    for (var i = 0; i < numberOfAttributes; ++i) {
      var attr = gl.getActiveAttrib(program, i);
      var location = gl.getAttribLocation(program, attr.name);

      attributes[attr.name] = {
        name: attr.name,
        type: attr.type,
        index: location,
      };
    }

    return attributes;
  }

  function findUniforms(gl, program) {
    var uniformsByName = {};
    var uniforms = [];
    var samplerUniforms = [];

    var numberOfUniforms = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);

    for (var i = 0; i < numberOfUniforms; ++i) {
      var activeUniform = gl.getActiveUniform(program, i);
      var suffix = "[0]";
      var uniformName =
        activeUniform.name.indexOf(
          suffix,
          activeUniform.name.length - suffix.length
        ) !== -1
          ? activeUniform.name.slice(0, activeUniform.name.length - 3)
          : activeUniform.name;

      // Ignore GLSL built-in uniforms returned in Firefox.
      if (uniformName.indexOf("gl_") !== 0) {
        if (activeUniform.name.indexOf("[") < 0) {
          // Single uniform
          var location = gl.getUniformLocation(program, uniformName);

          // IE 11.0.9 needs this check since getUniformLocation can return null
          // if the uniform is not active (e.g., it is optimized out).  Looks like
          // getActiveUniform() above returns uniforms that are not actually active.
          if (location !== null) {
            var uniform = createUniform$1(gl, activeUniform, uniformName, location);

            uniformsByName[uniformName] = uniform;
            uniforms.push(uniform);

            if (uniform._setSampler) {
              samplerUniforms.push(uniform);
            }
          }
        } else {
          // Uniform array

          var uniformArray;
          var locations;
          var value;
          var loc;

          // On some platforms - Nexus 4 in Firefox for one - an array of sampler2D ends up being represented
          // as separate uniforms, one for each array element.  Check for and handle that case.
          var indexOfBracket = uniformName.indexOf("[");
          if (indexOfBracket >= 0) {
            // We're assuming the array elements show up in numerical order - it seems to be true.
            uniformArray = uniformsByName[uniformName.slice(0, indexOfBracket)];

            // Nexus 4 with Android 4.3 needs this check, because it reports a uniform
            // with the strange name webgl_3467e0265d05c3c1[1] in our globe surface shader.
            if (!defined(uniformArray)) {
              continue;
            }

            locations = uniformArray._locations;

            // On the Nexus 4 in Chrome, we get one uniform per sampler, just like in Firefox,
            // but the size is not 1 like it is in Firefox.  So if we push locations here,
            // we'll end up adding too many locations.
            if (locations.length <= 1) {
              value = uniformArray.value;
              loc = gl.getUniformLocation(program, uniformName);

              // Workaround for IE 11.0.9.  See above.
              if (loc !== null) {
                locations.push(loc);
                value.push(gl.getUniform(program, loc));
              }
            }
          } else {
            locations = [];
            for (var j = 0; j < activeUniform.size; ++j) {
              loc = gl.getUniformLocation(program, uniformName + "[" + j + "]");

              // Workaround for IE 11.0.9.  See above.
              if (loc !== null) {
                locations.push(loc);
              }
            }
            uniformArray = createUniformArray(
              gl,
              activeUniform,
              uniformName,
              locations
            );

            uniformsByName[uniformName] = uniformArray;
            uniforms.push(uniformArray);

            if (uniformArray._setSampler) {
              samplerUniforms.push(uniformArray);
            }
          }
        }
      }
    }

    return {
      uniformsByName: uniformsByName,
      uniforms: uniforms,
      samplerUniforms: samplerUniforms,
    };
  }

  function partitionUniforms(shader, uniforms) {
    var automaticUniforms = [];
    var manualUniforms = [];

    for (var uniform in uniforms) {
      if (uniforms.hasOwnProperty(uniform)) {
        var uniformObject = uniforms[uniform];
        var uniformName = uniform;
        // if it's a duplicate uniform, use its original name so it is updated correctly
        var duplicateUniform = shader._duplicateUniformNames[uniformName];
        if (defined(duplicateUniform)) {
          uniformObject.name = duplicateUniform;
          uniformName = duplicateUniform;
        }
        var automaticUniform = AutomaticUniforms[uniformName];
        if (defined(automaticUniform)) {
          automaticUniforms.push({
            uniform: uniformObject,
            automaticUniform: automaticUniform,
          });
        } else {
          manualUniforms.push(uniformObject);
        }
      }
    }

    return {
      automaticUniforms: automaticUniforms,
      manualUniforms: manualUniforms,
    };
  }

  function setSamplerUniforms(gl, program, samplerUniforms) {
    gl.useProgram(program);

    var textureUnitIndex = 0;
    var length = samplerUniforms.length;
    for (var i = 0; i < length; ++i) {
      textureUnitIndex = samplerUniforms[i]._setSampler(textureUnitIndex);
    }

    gl.useProgram(null);

    return textureUnitIndex;
  }

  function initialize$1(shader) {
    if (defined(shader._program)) {
      return;
    }

    reinitialize(shader);
  }

  function reinitialize(shader) {
    var oldProgram = shader._program;

    var gl = shader._gl;
    var program = createAndLinkProgram(gl, shader, shader._debugShaders);
    var numberOfVertexAttributes = gl.getProgramParameter(
      program,
      gl.ACTIVE_ATTRIBUTES
    );
    var uniforms = findUniforms(gl, program);
    var partitionedUniforms = partitionUniforms(shader, uniforms.uniformsByName);

    shader._program = program;
    shader._numberOfVertexAttributes = numberOfVertexAttributes;
    shader._vertexAttributes = findVertexAttributes(
      gl,
      program,
      numberOfVertexAttributes
    );
    shader._uniformsByName = uniforms.uniformsByName;
    shader._uniforms = uniforms.uniforms;
    shader._automaticUniforms = partitionedUniforms.automaticUniforms;
    shader._manualUniforms = partitionedUniforms.manualUniforms;

    shader.maximumTextureUnitIndex = setSamplerUniforms(
      gl,
      program,
      uniforms.samplerUniforms
    );

    if (oldProgram) {
      shader._gl.deleteProgram(oldProgram);
    }

    // If SpectorJS is active, add the hook to make the shader editor work.
    // https://github.com/BabylonJS/Spector.js/blob/master/documentation/extension.md#shader-editor
    if (typeof spector !== "undefined") {
      shader._program.__SPECTOR_rebuildProgram = function (
        vertexSourceCode, // The new vertex shader source
        fragmentSourceCode, // The new fragment shader source
        onCompiled, // Callback triggered by your engine when the compilation is successful. It needs to send back the new linked program.
        onError // Callback triggered by your engine in case of error. It needs to send the WebGL error to allow the editor to display the error in the gutter.
      ) {
        var originalVS = shader._vertexShaderText;
        var originalFS = shader._fragmentShaderText;

        // SpectorJS likes to replace `!=` with `! =` for unknown reasons,
        // and that causes glsl compile failures. So fix that up.
        var regex = / ! = /g;
        shader._vertexShaderText = vertexSourceCode.replace(regex, " != ");
        shader._fragmentShaderText = fragmentSourceCode.replace(regex, " != ");

        try {
          reinitialize(shader);
          onCompiled(shader._program);
        } catch (e) {
          shader._vertexShaderText = originalVS;
          shader._fragmentShaderText = originalFS;

          // Only pass on the WebGL error:
          var errorMatcher = /(?:Compile|Link) error: ([^]*)/;
          var match = errorMatcher.exec(e.message);
          if (match) {
            onError(match[1]);
          } else {
            onError(e.message);
          }
        }
      };
    }
  }

  ShaderProgram.prototype._bind = function () {
    initialize$1(this);
    this._gl.useProgram(this._program);
  };

  ShaderProgram.prototype._setUniforms = function (
    uniformMap,
    uniformState,
    validate
  ) {
    var len;
    var i;

    if (defined(uniformMap)) {
      var manualUniforms = this._manualUniforms;
      len = manualUniforms.length;
      for (i = 0; i < len; ++i) {
        var mu = manualUniforms[i];
        mu.value = uniformMap[mu.name]();
      }
    }

    var automaticUniforms = this._automaticUniforms;
    len = automaticUniforms.length;
    for (i = 0; i < len; ++i) {
      var au = automaticUniforms[i];
      au.uniform.value = au.automaticUniform.getValue(uniformState);
    }

    ///////////////////////////////////////////////////////////////////

    // It appears that assigning the uniform values above and then setting them here
    // (which makes the GL calls) is faster than removing this loop and making
    // the GL calls above.  I suspect this is because each GL call pollutes the
    // L2 cache making our JavaScript and the browser/driver ping-pong cache lines.
    var uniforms = this._uniforms;
    len = uniforms.length;
    for (i = 0; i < len; ++i) {
      uniforms[i].set();
    }

    if (validate) {
      var gl = this._gl;
      var program = this._program;

      gl.validateProgram(program);
      //>>includeStart('debug', pragmas.debug);
      if (!gl.getProgramParameter(program, gl.VALIDATE_STATUS)) {
        throw new DeveloperError(
          "Program validation failed.  Program info log: " +
            gl.getProgramInfoLog(program)
        );
      }
      //>>includeEnd('debug');
    }
  };

  ShaderProgram.prototype.isDestroyed = function () {
    return false;
  };

  ShaderProgram.prototype.destroy = function () {
    this._cachedShader.cache.releaseShaderProgram(this);
    return undefined;
  };

  ShaderProgram.prototype.finalDestroy = function () {
    this._gl.deleteProgram(this._program);
    return destroyObject(this);
  };

  /**
   * A function to port GLSL shaders from GLSL ES 1.00 to GLSL ES 3.00
   *
   * This function is nowhere near comprehensive or complete. It just
   * handles some common cases.
   *
   * Note that this function requires the presence of the
   * "#define OUTPUT_DECLARATION" line that is appended
   * by ShaderSource.
   *
   * @private
   */
  function modernizeShader(source, isFragmentShader) {
    var outputDeclarationRegex = /#define OUTPUT_DECLARATION/;
    var splitSource = source.split("\n");

    if (/#version 300 es/g.test(source)) {
      return source;
    }

    var outputDeclarationLine = -1;
    var i, line;
    for (i = 0; i < splitSource.length; ++i) {
      line = splitSource[i];
      if (outputDeclarationRegex.test(line)) {
        outputDeclarationLine = i;
        break;
      }
    }

    if (outputDeclarationLine === -1) {
      throw new DeveloperError("Could not find a #define OUTPUT_DECLARATION!");
    }

    var outputVariables = [];

    for (i = 0; i < 10; i++) {
      var fragDataString = "gl_FragData\\[" + i + "\\]";
      var newOutput = "czm_out" + i;
      var regex = new RegExp(fragDataString, "g");
      if (regex.test(source)) {
        setAdd(newOutput, outputVariables);
        replaceInSourceString(fragDataString, newOutput, splitSource);
        splitSource.splice(
          outputDeclarationLine,
          0,
          "layout(location = " + i + ") out vec4 " + newOutput + ";"
        );
        outputDeclarationLine += 1;
      }
    }

    var czmFragColor = "czm_fragColor";
    if (findInSource("gl_FragColor", splitSource)) {
      setAdd(czmFragColor, outputVariables);
      replaceInSourceString("gl_FragColor", czmFragColor, splitSource);
      splitSource.splice(
        outputDeclarationLine,
        0,
        "layout(location = 0) out vec4 czm_fragColor;"
      );
      outputDeclarationLine += 1;
    }

    var variableMap = getVariablePreprocessorBranch(outputVariables, splitSource);
    var lineAdds = {};
    for (i = 0; i < splitSource.length; i++) {
      line = splitSource[i];
      for (var variable in variableMap) {
        if (variableMap.hasOwnProperty(variable)) {
          var matchVar = new RegExp(
            "(layout)[^]+(out)[^]+(" + variable + ")[^]+",
            "g"
          );
          if (matchVar.test(line)) {
            lineAdds[line] = variable;
          }
        }
      }
    }

    for (var layoutDeclaration in lineAdds) {
      if (lineAdds.hasOwnProperty(layoutDeclaration)) {
        var variableName = lineAdds[layoutDeclaration];
        var lineNumber = splitSource.indexOf(layoutDeclaration);
        var entry = variableMap[variableName];
        var depth = entry.length;
        var d;
        for (d = 0; d < depth; d++) {
          splitSource.splice(lineNumber, 0, entry[d]);
        }
        lineNumber += depth + 1;
        for (d = depth - 1; d >= 0; d--) {
          splitSource.splice(lineNumber, 0, "#endif //" + entry[d]);
        }
      }
    }

    var webgl2UniqueID = "WEBGL_2";
    var webgl2DefineMacro = "#define " + webgl2UniqueID;
    var versionThree = "#version 300 es";
    var foundVersion = false;
    for (i = 0; i < splitSource.length; i++) {
      if (/#version/.test(splitSource[i])) {
        splitSource[i] = versionThree;
        foundVersion = true;
        break;
      }
    }

    if (!foundVersion) {
      splitSource.splice(0, 0, versionThree);
    }

    splitSource.splice(1, 0, webgl2DefineMacro);

    removeExtension("EXT_draw_buffers", webgl2UniqueID, splitSource);
    removeExtension("EXT_frag_depth", webgl2UniqueID, splitSource);
    removeExtension("OES_standard_derivatives", webgl2UniqueID, splitSource);

    replaceInSourceString("texture2D", "texture", splitSource);
    replaceInSourceString("texture3D", "texture", splitSource);
    replaceInSourceString("textureCube", "texture", splitSource);
    replaceInSourceString("gl_FragDepthEXT", "gl_FragDepth", splitSource);

    if (isFragmentShader) {
      replaceInSourceString("varying", "in", splitSource);
    } else {
      replaceInSourceString("attribute", "in", splitSource);
      replaceInSourceString("varying", "out", splitSource);
    }

    return compileSource(splitSource);
  }

  // Note that this fails if your string looks like
  // searchString[singleCharacter]searchString
  function replaceInSourceString(str, replacement, splitSource) {
    var regexStr = "(^|[^\\w])(" + str + ")($|[^\\w])";
    var regex = new RegExp(regexStr, "g");

    var splitSourceLength = splitSource.length;
    for (var i = 0; i < splitSourceLength; ++i) {
      var line = splitSource[i];
      splitSource[i] = line.replace(regex, "$1" + replacement + "$3");
    }
  }

  function replaceInSourceRegex(regex, replacement, splitSource) {
    var splitSourceLength = splitSource.length;
    for (var i = 0; i < splitSourceLength; ++i) {
      var line = splitSource[i];
      splitSource[i] = line.replace(regex, replacement);
    }
  }

  function findInSource(str, splitSource) {
    var regexStr = "(^|[^\\w])(" + str + ")($|[^\\w])";
    var regex = new RegExp(regexStr, "g");

    var splitSourceLength = splitSource.length;
    for (var i = 0; i < splitSourceLength; ++i) {
      var line = splitSource[i];
      if (regex.test(line)) {
        return true;
      }
    }
    return false;
  }

  function compileSource(splitSource) {
    var wholeSource = "";

    var splitSourceLength = splitSource.length;
    for (var i = 0; i < splitSourceLength; ++i) {
      wholeSource += splitSource[i] + "\n";
    }
    return wholeSource;
  }

  function setAdd(variable, set) {
    if (set.indexOf(variable) === -1) {
      set.push(variable);
    }
  }

  function getVariablePreprocessorBranch(layoutVariables, splitSource) {
    var variableMap = {};

    var numLayoutVariables = layoutVariables.length;

    var stack = [];
    for (var i = 0; i < splitSource.length; ++i) {
      var line = splitSource[i];
      var hasIF = /(#ifdef|#if)/g.test(line);
      var hasELSE = /#else/g.test(line);
      var hasENDIF = /#endif/g.test(line);

      if (hasIF) {
        stack.push(line);
      } else if (hasELSE) {
        var top = stack[stack.length - 1];
        var op = top.replace("ifdef", "ifndef");
        if (/if/g.test(op)) {
          op = op.replace(/(#if\s+)(\S*)([^]*)/, "$1!($2)$3");
        }
        stack.pop();
        stack.push(op);
      } else if (hasENDIF) {
        stack.pop();
      } else if (!/layout/g.test(line)) {
        for (var varIndex = 0; varIndex < numLayoutVariables; ++varIndex) {
          var varName = layoutVariables[varIndex];
          if (line.indexOf(varName) !== -1) {
            if (!defined(variableMap[varName])) {
              variableMap[varName] = stack.slice();
            } else {
              variableMap[varName] = variableMap[varName].filter(function (x) {
                return stack.indexOf(x) >= 0;
              });
            }
          }
        }
      }
    }

    return variableMap;
  }

  function removeExtension(name, webgl2UniqueID, splitSource) {
    var regex = "#extension\\s+GL_" + name + "\\s+:\\s+[a-zA-Z0-9]+\\s*$";
    replaceInSourceRegex(new RegExp(regex, "g"), "", splitSource);

    // replace any possible directive #ifdef (GL_EXT_extension) with WEBGL_2 unique directive
    replaceInSourceString("GL_" + name, webgl2UniqueID, splitSource);
  }

  //This file is automatically rebuilt by the Cesium build process.
  var czm_degreesPerRadian = "const float czm_degreesPerRadian = 57.29577951308232;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_depthRange = "const czm_depthRangeStruct czm_depthRange = czm_depthRangeStruct(0.0, 1.0);\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon1 = "const float czm_epsilon1 = 0.1;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon2 = "const float czm_epsilon2 = 0.01;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon3 = "const float czm_epsilon3 = 0.001;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon4 = "const float czm_epsilon4 = 0.0001;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon5 = "const float czm_epsilon5 = 0.00001;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon6 = "const float czm_epsilon6 = 0.000001;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_epsilon7 = "const float czm_epsilon7 = 0.0000001;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_infinity = "const float czm_infinity = 5906376272000.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_oneOverPi = "const float czm_oneOverPi = 0.3183098861837907;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_oneOverTwoPi = "const float czm_oneOverTwoPi = 0.15915494309189535;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passCesium3DTile = "const float czm_passCesium3DTile = 4.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passCesium3DTileClassification = "const float czm_passCesium3DTileClassification = 5.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passCesium3DTileClassificationIgnoreShow = "const float czm_passCesium3DTileClassificationIgnoreShow = 6.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passClassification = "const float czm_passClassification = 7.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passCompute = "const float czm_passCompute = 1.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passEnvironment = "const float czm_passEnvironment = 0.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passGlobe = "const float czm_passGlobe = 2.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passOpaque = "const float czm_passOpaque = 7.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passOverlay = "const float czm_passOverlay = 9.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passTerrainClassification = "const float czm_passTerrainClassification = 3.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_passTranslucent = "const float czm_passTranslucent = 8.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_pi = "const float czm_pi = 3.141592653589793;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_piOverFour = "const float czm_piOverFour = 0.7853981633974483;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_piOverSix = "const float czm_piOverSix = 0.5235987755982988;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_piOverThree = "const float czm_piOverThree = 1.0471975511965976;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_piOverTwo = "const float czm_piOverTwo = 1.5707963267948966;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_radiansPerDegree = "const float czm_radiansPerDegree = 0.017453292519943295;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_sceneMode2D = "const float czm_sceneMode2D = 2.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_sceneMode3D = "const float czm_sceneMode3D = 3.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_sceneModeColumbusView = "const float czm_sceneModeColumbusView = 1.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_sceneModeMorphing = "const float czm_sceneModeMorphing = 0.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_solarRadius = "const float czm_solarRadius = 695500000.0;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_threePiOver2 = "const float czm_threePiOver2 = 4.71238898038469;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_twoPi = "const float czm_twoPi = 6.283185307179586;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_webMercatorMaxLatitude = "const float czm_webMercatorMaxLatitude = 1.4844222297453324;\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_depthRangeStruct = "struct czm_depthRangeStruct\n\
{\n\
float near;\n\
float far;\n\
};\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_material = "struct czm_material\n\
{\n\
vec3 diffuse;\n\
float specular;\n\
float shininess;\n\
vec3 normal;\n\
vec3 emission;\n\
float alpha;\n\
};\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_materialInput = "struct czm_materialInput\n\
{\n\
float s;\n\
vec2 st;\n\
vec3 str;\n\
vec3 normalEC;\n\
mat3 tangentToEyeMatrix;\n\
vec3 positionToEyeEC;\n\
float height;\n\
float slope;\n\
float aspect;\n\
};\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_ray = "struct czm_ray\n\
{\n\
vec3 origin;\n\
vec3 direction;\n\
};\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_raySegment = "struct czm_raySegment\n\
{\n\
float start;\n\
float stop;\n\
};\n\
const czm_raySegment czm_emptyRaySegment = czm_raySegment(-czm_infinity, -czm_infinity);\n\
const czm_raySegment czm_fullRaySegment = czm_raySegment(0.0, czm_infinity);\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_shadowParameters = "struct czm_shadowParameters\n\
{\n\
#ifdef USE_CUBE_MAP_SHADOW\n\
vec3 texCoords;\n\
#else\n\
vec2 texCoords;\n\
#endif\n\
float depthBias;\n\
float depth;\n\
float nDotL;\n\
vec2 texelStepSize;\n\
float normalShadingSmooth;\n\
float darkness;\n\
};\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_HSBToRGB = "const vec4 K_HSB2RGB = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);\n\
vec3 czm_HSBToRGB(vec3 hsb)\n\
{\n\
vec3 p = abs(fract(hsb.xxx + K_HSB2RGB.xyz) * 6.0 - K_HSB2RGB.www);\n\
return hsb.z * mix(K_HSB2RGB.xxx, clamp(p - K_HSB2RGB.xxx, 0.0, 1.0), hsb.y);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_HSLToRGB = "vec3 hueToRGB(float hue)\n\
{\n\
float r = abs(hue * 6.0 - 3.0) - 1.0;\n\
float g = 2.0 - abs(hue * 6.0 - 2.0);\n\
float b = 2.0 - abs(hue * 6.0 - 4.0);\n\
return clamp(vec3(r, g, b), 0.0, 1.0);\n\
}\n\
vec3 czm_HSLToRGB(vec3 hsl)\n\
{\n\
vec3 rgb = hueToRGB(hsl.x);\n\
float c = (1.0 - abs(2.0 * hsl.z - 1.0)) * hsl.y;\n\
return (rgb - 0.5) * c + hsl.z;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_RGBToHSB = "const vec4 K_RGB2HSB = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);\n\
vec3 czm_RGBToHSB(vec3 rgb)\n\
{\n\
vec4 p = mix(vec4(rgb.bg, K_RGB2HSB.wz), vec4(rgb.gb, K_RGB2HSB.xy), step(rgb.b, rgb.g));\n\
vec4 q = mix(vec4(p.xyw, rgb.r), vec4(rgb.r, p.yzx), step(p.x, rgb.r));\n\
float d = q.x - min(q.w, q.y);\n\
return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + czm_epsilon7)), d / (q.x + czm_epsilon7), q.x);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_RGBToHSL = "vec3 RGBtoHCV(vec3 rgb)\n\
{\n\
vec4 p = (rgb.g < rgb.b) ? vec4(rgb.bg, -1.0, 2.0 / 3.0) : vec4(rgb.gb, 0.0, -1.0 / 3.0);\n\
vec4 q = (rgb.r < p.x) ? vec4(p.xyw, rgb.r) : vec4(rgb.r, p.yzx);\n\
float c = q.x - min(q.w, q.y);\n\
float h = abs((q.w - q.y) / (6.0 * c + czm_epsilon7) + q.z);\n\
return vec3(h, c, q.x);\n\
}\n\
vec3 czm_RGBToHSL(vec3 rgb)\n\
{\n\
vec3 hcv = RGBtoHCV(rgb);\n\
float l = hcv.z - hcv.y * 0.5;\n\
float s = hcv.y / (1.0 - abs(l * 2.0 - 1.0) + czm_epsilon7);\n\
return vec3(hcv.x, s, l);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_RGBToXYZ = "vec3 czm_RGBToXYZ(vec3 rgb)\n\
{\n\
const mat3 RGB2XYZ = mat3(0.4124, 0.2126, 0.0193,\n\
0.3576, 0.7152, 0.1192,\n\
0.1805, 0.0722, 0.9505);\n\
vec3 xyz = RGB2XYZ * rgb;\n\
vec3 Yxy;\n\
Yxy.r = xyz.g;\n\
float temp = dot(vec3(1.0), xyz);\n\
Yxy.gb = xyz.rg / temp;\n\
return Yxy;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_XYZToRGB = "vec3 czm_XYZToRGB(vec3 Yxy)\n\
{\n\
const mat3 XYZ2RGB = mat3( 3.2405, -0.9693,  0.0556,\n\
-1.5371,  1.8760, -0.2040,\n\
-0.4985,  0.0416,  1.0572);\n\
vec3 xyz;\n\
xyz.r = Yxy.r * Yxy.g / Yxy.b;\n\
xyz.g = Yxy.r;\n\
xyz.b = Yxy.r * (1.0 - Yxy.g - Yxy.b) / Yxy.b;\n\
return XYZ2RGB * xyz;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_acesTonemapping = "vec3 czm_acesTonemapping(vec3 color) {\n\
float g = 0.985;\n\
float a = 0.065;\n\
float b = 0.0001;\n\
float c = 0.433;\n\
float d = 0.238;\n\
color = (color * (color + a) - b) / (color * (g * color + c) + d);\n\
color = clamp(color, 0.0, 1.0);\n\
return color;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_alphaWeight = "float czm_alphaWeight(float a)\n\
{\n\
float z = (gl_FragCoord.z - czm_viewportTransformation[3][2]) / czm_viewportTransformation[2][2];\n\
return pow(a + 0.01, 4.0) + max(1e-2, min(3.0 * 1e3, 0.003 / (1e-5 + pow(abs(z) / 200.0, 4.0))));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_antialias = "vec4 czm_antialias(vec4 color1, vec4 color2, vec4 currentColor, float dist, float fuzzFactor)\n\
{\n\
float val1 = clamp(dist / fuzzFactor, 0.0, 1.0);\n\
float val2 = clamp((dist - 0.5) / fuzzFactor, 0.0, 1.0);\n\
val1 = val1 * (1.0 - val2);\n\
val1 = val1 * val1 * (3.0 - (2.0 * val1));\n\
val1 = pow(val1, 0.5);\n\
vec4 midColor = (color1 + color2) * 0.5;\n\
return mix(midColor, currentColor, val1);\n\
}\n\
vec4 czm_antialias(vec4 color1, vec4 color2, vec4 currentColor, float dist)\n\
{\n\
return czm_antialias(color1, color2, currentColor, dist, 0.1);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_approximateSphericalCoordinates = "vec2 czm_approximateSphericalCoordinates(vec3 normal) {\n\
float latitudeApproximation = czm_fastApproximateAtan(sqrt(normal.x * normal.x + normal.y * normal.y), normal.z);\n\
float longitudeApproximation = czm_fastApproximateAtan(normal.x, normal.y);\n\
return vec2(latitudeApproximation, longitudeApproximation);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_backFacing = "bool czm_backFacing()\n\
{\n\
return gl_FrontFacing == false;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_branchFreeTernary = "float czm_branchFreeTernary(bool comparison, float a, float b) {\n\
float useA = float(comparison);\n\
return a * useA + b * (1.0 - useA);\n\
}\n\
vec2 czm_branchFreeTernary(bool comparison, vec2 a, vec2 b) {\n\
float useA = float(comparison);\n\
return a * useA + b * (1.0 - useA);\n\
}\n\
vec3 czm_branchFreeTernary(bool comparison, vec3 a, vec3 b) {\n\
float useA = float(comparison);\n\
return a * useA + b * (1.0 - useA);\n\
}\n\
vec4 czm_branchFreeTernary(bool comparison, vec4 a, vec4 b) {\n\
float useA = float(comparison);\n\
return a * useA + b * (1.0 - useA);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_cascadeColor = "vec4 czm_cascadeColor(vec4 weights)\n\
{\n\
return vec4(1.0, 0.0, 0.0, 1.0) * weights.x +\n\
vec4(0.0, 1.0, 0.0, 1.0) * weights.y +\n\
vec4(0.0, 0.0, 1.0, 1.0) * weights.z +\n\
vec4(1.0, 0.0, 1.0, 1.0) * weights.w;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_cascadeDistance = "uniform vec4 shadowMap_cascadeDistances;\n\
float czm_cascadeDistance(vec4 weights)\n\
{\n\
return dot(shadowMap_cascadeDistances, weights);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_cascadeMatrix = "uniform mat4 shadowMap_cascadeMatrices[4];\n\
mat4 czm_cascadeMatrix(vec4 weights)\n\
{\n\
return shadowMap_cascadeMatrices[0] * weights.x +\n\
shadowMap_cascadeMatrices[1] * weights.y +\n\
shadowMap_cascadeMatrices[2] * weights.z +\n\
shadowMap_cascadeMatrices[3] * weights.w;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_cascadeWeights = "uniform vec4 shadowMap_cascadeSplits[2];\n\
vec4 czm_cascadeWeights(float depthEye)\n\
{\n\
vec4 near = step(shadowMap_cascadeSplits[0], vec4(depthEye));\n\
vec4 far = step(depthEye, shadowMap_cascadeSplits[1]);\n\
return near * far;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_columbusViewMorph = "vec4 czm_columbusViewMorph(vec4 position2D, vec4 position3D, float time)\n\
{\n\
vec3 p = mix(position2D.xyz, position3D.xyz, time);\n\
return vec4(p, 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_computePosition = "vec4 czm_computePosition();\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_cosineAndSine = "vec2 cordic(float angle)\n\
{\n\
vec2 vector = vec2(6.0725293500888267e-1, 0.0);\n\
float sense = (angle < 0.0) ? -1.0 : 1.0;\n\
mat2 rotation = mat2(1.0, sense, -sense, 1.0);\n\
vector = rotation * vector;\n\
angle -= sense * 7.8539816339744828e-1;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
float factor = sense * 5.0e-1;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 4.6364760900080609e-1;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 2.5e-1;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 2.4497866312686414e-1;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.25e-1;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 1.2435499454676144e-1;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 6.25e-2;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 6.2418809995957350e-2;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 3.125e-2;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 3.1239833430268277e-2;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.5625e-2;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 1.5623728620476831e-2;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 7.8125e-3;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 7.8123410601011111e-3;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 3.90625e-3;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 3.9062301319669718e-3;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.953125e-3;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 1.9531225164788188e-3;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 9.765625e-4;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 9.7656218955931946e-4;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 4.8828125e-4;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 4.8828121119489829e-4;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 2.44140625e-4;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 2.4414062014936177e-4;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.220703125e-4;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 1.2207031189367021e-4;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 6.103515625e-5;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 6.1035156174208773e-5;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 3.0517578125e-5;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 3.0517578115526096e-5;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.52587890625e-5;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 1.5258789061315762e-5;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 7.62939453125e-6;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 7.6293945311019700e-6;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 3.814697265625e-6;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 3.8146972656064961e-6;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.9073486328125e-6;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 1.9073486328101870e-6;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 9.5367431640625e-7;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 9.5367431640596084e-7;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 4.76837158203125e-7;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 4.7683715820308884e-7;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 2.384185791015625e-7;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
angle -= sense * 2.3841857910155797e-7;\n\
sense = (angle < 0.0) ? -1.0 : 1.0;\n\
factor = sense * 1.1920928955078125e-7;\n\
rotation[0][1] = factor;\n\
rotation[1][0] = -factor;\n\
vector = rotation * vector;\n\
return vector;\n\
}\n\
vec2 czm_cosineAndSine(float angle)\n\
{\n\
if (angle < -czm_piOverTwo || angle > czm_piOverTwo)\n\
{\n\
if (angle < 0.0)\n\
{\n\
return -cordic(angle + czm_pi);\n\
}\n\
else\n\
{\n\
return -cordic(angle - czm_pi);\n\
}\n\
}\n\
else\n\
{\n\
return cordic(angle);\n\
}\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_decompressTextureCoordinates = "vec2 czm_decompressTextureCoordinates(float encoded)\n\
{\n\
float temp = encoded / 4096.0;\n\
float xZeroTo4095 = floor(temp);\n\
float stx = xZeroTo4095 / 4095.0;\n\
float sty = (encoded - xZeroTo4095 * 4096.0) / 4095.0;\n\
return vec2(stx, sty);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_depthClamp = "#ifndef LOG_DEPTH\n\
varying float v_WindowZ;\n\
#endif\n\
vec4 czm_depthClamp(vec4 coords)\n\
{\n\
#ifndef LOG_DEPTH\n\
v_WindowZ = (0.5 * (coords.z / coords.w) + 0.5) * coords.w;\n\
coords.z = clamp(coords.z, -coords.w, +coords.w);\n\
#endif\n\
return coords;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_eastNorthUpToEyeCoordinates = "mat3 czm_eastNorthUpToEyeCoordinates(vec3 positionMC, vec3 normalEC)\n\
{\n\
vec3 tangentMC = normalize(vec3(-positionMC.y, positionMC.x, 0.0));\n\
vec3 tangentEC = normalize(czm_normal3D * tangentMC);\n\
vec3 bitangentEC = normalize(cross(normalEC, tangentEC));\n\
return mat3(\n\
tangentEC.x,   tangentEC.y,   tangentEC.z,\n\
bitangentEC.x, bitangentEC.y, bitangentEC.z,\n\
normalEC.x,    normalEC.y,    normalEC.z);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_ellipsoidContainsPoint = "bool czm_ellipsoidContainsPoint(vec3 ellipsoid_inverseRadii, vec3 point)\n\
{\n\
vec3 scaled = ellipsoid_inverseRadii * (czm_inverseModelView * vec4(point, 1.0)).xyz;\n\
return (dot(scaled, scaled) <= 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_ellipsoidWgs84TextureCoordinates = "vec2 czm_ellipsoidWgs84TextureCoordinates(vec3 normal)\n\
{\n\
return vec2(atan(normal.y, normal.x) * czm_oneOverTwoPi + 0.5, asin(normal.z) * czm_oneOverPi + 0.5);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_equalsEpsilon = "bool czm_equalsEpsilon(vec4 left, vec4 right, float epsilon) {\n\
return all(lessThanEqual(abs(left - right), vec4(epsilon)));\n\
}\n\
bool czm_equalsEpsilon(vec3 left, vec3 right, float epsilon) {\n\
return all(lessThanEqual(abs(left - right), vec3(epsilon)));\n\
}\n\
bool czm_equalsEpsilon(vec2 left, vec2 right, float epsilon) {\n\
return all(lessThanEqual(abs(left - right), vec2(epsilon)));\n\
}\n\
bool czm_equalsEpsilon(float left, float right, float epsilon) {\n\
return (abs(left - right) <= epsilon);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_eyeOffset = "vec4 czm_eyeOffset(vec4 positionEC, vec3 eyeOffset)\n\
{\n\
vec4 p = positionEC;\n\
vec4 zEyeOffset = normalize(p) * eyeOffset.z;\n\
p.xy += eyeOffset.xy + zEyeOffset.xy;\n\
p.z += zEyeOffset.z;\n\
return p;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_eyeToWindowCoordinates = "vec4 czm_eyeToWindowCoordinates(vec4 positionEC)\n\
{\n\
vec4 q = czm_projection * positionEC;\n\
q.xyz /= q.w;\n\
q.xyz = (czm_viewportTransformation * vec4(q.xyz, 1.0)).xyz;\n\
return q;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_fastApproximateAtan = "float czm_fastApproximateAtan(float x) {\n\
return x * (-0.1784 * x - 0.0663 * x * x + 1.0301);\n\
}\n\
float czm_fastApproximateAtan(float x, float y) {\n\
float t = abs(x);\n\
float opposite = abs(y);\n\
float adjacent = max(t, opposite);\n\
opposite = min(t, opposite);\n\
t = czm_fastApproximateAtan(opposite / adjacent);\n\
t = czm_branchFreeTernary(abs(y) > abs(x), czm_piOverTwo - t, t);\n\
t = czm_branchFreeTernary(x < 0.0, czm_pi - t, t);\n\
t = czm_branchFreeTernary(y < 0.0, -t, t);\n\
return t;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_fog = "vec3 czm_fog(float distanceToCamera, vec3 color, vec3 fogColor)\n\
{\n\
float scalar = distanceToCamera * czm_fogDensity;\n\
float fog = 1.0 - exp(-(scalar * scalar));\n\
return mix(color, fogColor, fog);\n\
}\n\
vec3 czm_fog(float distanceToCamera, vec3 color, vec3 fogColor, float fogModifierConstant)\n\
{\n\
float scalar = distanceToCamera * czm_fogDensity;\n\
float fog = 1.0 - exp(-((fogModifierConstant * scalar + fogModifierConstant) * (scalar * (1.0 + fogModifierConstant))));\n\
return mix(color, fogColor, fog);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_gammaCorrect = "vec3 czm_gammaCorrect(vec3 color) {\n\
#ifdef HDR\n\
color = pow(color, vec3(czm_gamma));\n\
#endif\n\
return color;\n\
}\n\
vec4 czm_gammaCorrect(vec4 color) {\n\
#ifdef HDR\n\
color.rgb = pow(color.rgb, vec3(czm_gamma));\n\
#endif\n\
return color;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_geodeticSurfaceNormal = "vec3 czm_geodeticSurfaceNormal(vec3 positionOnEllipsoid, vec3 ellipsoidCenter, vec3 oneOverEllipsoidRadiiSquared)\n\
{\n\
return normalize((positionOnEllipsoid - ellipsoidCenter) * oneOverEllipsoidRadiiSquared);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_getDefaultMaterial = "czm_material czm_getDefaultMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material;\n\
material.diffuse = vec3(0.0);\n\
material.specular = 0.0;\n\
material.shininess = 1.0;\n\
material.normal = materialInput.normalEC;\n\
material.emission = vec3(0.0);\n\
material.alpha = 1.0;\n\
return material;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_getLambertDiffuse = "float czm_getLambertDiffuse(vec3 lightDirectionEC, vec3 normalEC)\n\
{\n\
return max(dot(lightDirectionEC, normalEC), 0.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_getSpecular = "float czm_getSpecular(vec3 lightDirectionEC, vec3 toEyeEC, vec3 normalEC, float shininess)\n\
{\n\
vec3 toReflectedLight = reflect(-lightDirectionEC, normalEC);\n\
float specular = max(dot(toReflectedLight, toEyeEC), 0.0);\n\
return pow(specular, max(shininess, czm_epsilon2));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_getWaterNoise = "vec4 czm_getWaterNoise(sampler2D normalMap, vec2 uv, float time, float angleInRadians)\n\
{\n\
float cosAngle = cos(angleInRadians);\n\
float sinAngle = sin(angleInRadians);\n\
vec2 s0 = vec2(1.0/17.0, 0.0);\n\
vec2 s1 = vec2(-1.0/29.0, 0.0);\n\
vec2 s2 = vec2(1.0/101.0, 1.0/59.0);\n\
vec2 s3 = vec2(-1.0/109.0, -1.0/57.0);\n\
s0 = vec2((cosAngle * s0.x) - (sinAngle * s0.y), (sinAngle * s0.x) + (cosAngle * s0.y));\n\
s1 = vec2((cosAngle * s1.x) - (sinAngle * s1.y), (sinAngle * s1.x) + (cosAngle * s1.y));\n\
s2 = vec2((cosAngle * s2.x) - (sinAngle * s2.y), (sinAngle * s2.x) + (cosAngle * s2.y));\n\
s3 = vec2((cosAngle * s3.x) - (sinAngle * s3.y), (sinAngle * s3.x) + (cosAngle * s3.y));\n\
vec2 uv0 = (uv/103.0) + (time * s0);\n\
vec2 uv1 = uv/107.0 + (time * s1) + vec2(0.23);\n\
vec2 uv2 = uv/vec2(897.0, 983.0) + (time * s2) + vec2(0.51);\n\
vec2 uv3 = uv/vec2(991.0, 877.0) + (time * s3) + vec2(0.71);\n\
uv0 = fract(uv0);\n\
uv1 = fract(uv1);\n\
uv2 = fract(uv2);\n\
uv3 = fract(uv3);\n\
vec4 noise = (texture2D(normalMap, uv0)) +\n\
(texture2D(normalMap, uv1)) +\n\
(texture2D(normalMap, uv2)) +\n\
(texture2D(normalMap, uv3));\n\
return ((noise / 4.0) - 0.5) * 2.0;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_hue = "vec3 czm_hue(vec3 rgb, float adjustment)\n\
{\n\
const mat3 toYIQ = mat3(0.299,     0.587,     0.114,\n\
0.595716, -0.274453, -0.321263,\n\
0.211456, -0.522591,  0.311135);\n\
const mat3 toRGB = mat3(1.0,  0.9563,  0.6210,\n\
1.0, -0.2721, -0.6474,\n\
1.0, -1.107,   1.7046);\n\
vec3 yiq = toYIQ * rgb;\n\
float hue = atan(yiq.z, yiq.y) + adjustment;\n\
float chroma = sqrt(yiq.z * yiq.z + yiq.y * yiq.y);\n\
vec3 color = vec3(yiq.x, chroma * cos(hue), chroma * sin(hue));\n\
return toRGB * color;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_inverseGamma = "vec3 czm_inverseGamma(vec3 color) {\n\
return pow(color, vec3(1.0 / czm_gamma));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_isEmpty = "bool czm_isEmpty(czm_raySegment interval)\n\
{\n\
return (interval.stop < 0.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_isFull = "bool czm_isFull(czm_raySegment interval)\n\
{\n\
return (interval.start == 0.0 && interval.stop == czm_infinity);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_latitudeToWebMercatorFraction = "float czm_latitudeToWebMercatorFraction(float latitude, float southMercatorY, float oneOverMercatorHeight)\n\
{\n\
float sinLatitude = sin(latitude);\n\
float mercatorY = 0.5 * log((1.0 + sinLatitude) / (1.0 - sinLatitude));\n\
return (mercatorY - southMercatorY) * oneOverMercatorHeight;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_lineDistance = "float czm_lineDistance(vec2 point1, vec2 point2, vec2 point) {\n\
return abs((point2.y - point1.y) * point.x - (point2.x - point1.x) * point.y + point2.x * point1.y - point2.y * point1.x) / distance(point2, point1);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_luminance = "float czm_luminance(vec3 rgb)\n\
{\n\
const vec3 W = vec3(0.2125, 0.7154, 0.0721);\n\
return dot(rgb, W);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_metersPerPixel = "float czm_metersPerPixel(vec4 positionEC, float pixelRatio)\n\
{\n\
float width = czm_viewport.z;\n\
float height = czm_viewport.w;\n\
float pixelWidth;\n\
float pixelHeight;\n\
float top = czm_frustumPlanes.x;\n\
float bottom = czm_frustumPlanes.y;\n\
float left = czm_frustumPlanes.z;\n\
float right = czm_frustumPlanes.w;\n\
if (czm_sceneMode == czm_sceneMode2D || czm_orthographicIn3D == 1.0)\n\
{\n\
float frustumWidth = right - left;\n\
float frustumHeight = top - bottom;\n\
pixelWidth = frustumWidth / width;\n\
pixelHeight = frustumHeight / height;\n\
}\n\
else\n\
{\n\
float distanceToPixel = -positionEC.z;\n\
float inverseNear = 1.0 / czm_currentFrustum.x;\n\
float tanTheta = top * inverseNear;\n\
pixelHeight = 2.0 * distanceToPixel * tanTheta / height;\n\
tanTheta = right * inverseNear;\n\
pixelWidth = 2.0 * distanceToPixel * tanTheta / width;\n\
}\n\
return max(pixelWidth, pixelHeight) * pixelRatio;\n\
}\n\
float czm_metersPerPixel(vec4 positionEC)\n\
{\n\
return czm_metersPerPixel(positionEC, czm_pixelRatio);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_modelToWindowCoordinates = "vec4 czm_modelToWindowCoordinates(vec4 position)\n\
{\n\
vec4 q = czm_modelViewProjection * position;\n\
q.xyz /= q.w;\n\
q.xyz = (czm_viewportTransformation * vec4(q.xyz, 1.0)).xyz;\n\
return q;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_multiplyWithColorBalance = "vec3 czm_multiplyWithColorBalance(vec3 left, vec3 right)\n\
{\n\
const vec3 W = vec3(0.2125, 0.7154, 0.0721);\n\
vec3 target = left * right;\n\
float leftLuminance = dot(left, W);\n\
float rightLuminance = dot(right, W);\n\
float targetLuminance = dot(target, W);\n\
return ((leftLuminance + rightLuminance) / (2.0 * targetLuminance)) * target;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_nearFarScalar = "float czm_nearFarScalar(vec4 nearFarScalar, float cameraDistSq)\n\
{\n\
float valueAtMin = nearFarScalar.y;\n\
float valueAtMax = nearFarScalar.w;\n\
float nearDistanceSq = nearFarScalar.x * nearFarScalar.x;\n\
float farDistanceSq = nearFarScalar.z * nearFarScalar.z;\n\
float t = (cameraDistSq - nearDistanceSq) / (farDistanceSq - nearDistanceSq);\n\
t = pow(clamp(t, 0.0, 1.0), 0.2);\n\
return mix(valueAtMin, valueAtMax, t);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_octDecode = "vec3 czm_octDecode(vec2 encoded, float range)\n\
{\n\
if (encoded.x == 0.0 && encoded.y == 0.0) {\n\
return vec3(0.0, 0.0, 0.0);\n\
}\n\
encoded = encoded / range * 2.0 - 1.0;\n\
vec3 v = vec3(encoded.x, encoded.y, 1.0 - abs(encoded.x) - abs(encoded.y));\n\
if (v.z < 0.0)\n\
{\n\
v.xy = (1.0 - abs(v.yx)) * czm_signNotZero(v.xy);\n\
}\n\
return normalize(v);\n\
}\n\
vec3 czm_octDecode(vec2 encoded)\n\
{\n\
return czm_octDecode(encoded, 255.0);\n\
}\n\
vec3 czm_octDecode(float encoded)\n\
{\n\
float temp = encoded / 256.0;\n\
float x = floor(temp);\n\
float y = (temp - x) * 256.0;\n\
return czm_octDecode(vec2(x, y));\n\
}\n\
void czm_octDecode(vec2 encoded, out vec3 vector1, out vec3 vector2, out vec3 vector3)\n\
{\n\
float temp = encoded.x / 65536.0;\n\
float x = floor(temp);\n\
float encodedFloat1 = (temp - x) * 65536.0;\n\
temp = encoded.y / 65536.0;\n\
float y = floor(temp);\n\
float encodedFloat2 = (temp - y) * 65536.0;\n\
vector1 = czm_octDecode(encodedFloat1);\n\
vector2 = czm_octDecode(encodedFloat2);\n\
vector3 = czm_octDecode(vec2(x, y));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_packDepth = "vec4 czm_packDepth(float depth)\n\
{\n\
vec4 enc = vec4(1.0, 255.0, 65025.0, 16581375.0) * depth;\n\
enc = fract(enc);\n\
enc -= enc.yzww * vec4(1.0 / 255.0, 1.0 / 255.0, 1.0 / 255.0, 0.0);\n\
return enc;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_phong = "float czm_private_getLambertDiffuseOfMaterial(vec3 lightDirectionEC, czm_material material)\n\
{\n\
return czm_getLambertDiffuse(lightDirectionEC, material.normal);\n\
}\n\
float czm_private_getSpecularOfMaterial(vec3 lightDirectionEC, vec3 toEyeEC, czm_material material)\n\
{\n\
return czm_getSpecular(lightDirectionEC, toEyeEC, material.normal, material.shininess);\n\
}\n\
vec4 czm_phong(vec3 toEye, czm_material material, vec3 lightDirectionEC)\n\
{\n\
float diffuse = czm_private_getLambertDiffuseOfMaterial(vec3(0.0, 0.0, 1.0), material);\n\
if (czm_sceneMode == czm_sceneMode3D) {\n\
diffuse += czm_private_getLambertDiffuseOfMaterial(vec3(0.0, 1.0, 0.0), material);\n\
}\n\
float specular = czm_private_getSpecularOfMaterial(lightDirectionEC, toEye, material);\n\
vec3 materialDiffuse = material.diffuse * 0.5;\n\
vec3 ambient = materialDiffuse;\n\
vec3 color = ambient + material.emission;\n\
color += materialDiffuse * diffuse * czm_lightColor;\n\
color += material.specular * specular * czm_lightColor;\n\
return vec4(color, material.alpha);\n\
}\n\
vec4 czm_private_phong(vec3 toEye, czm_material material, vec3 lightDirectionEC)\n\
{\n\
float diffuse = czm_private_getLambertDiffuseOfMaterial(lightDirectionEC, material);\n\
float specular = czm_private_getSpecularOfMaterial(lightDirectionEC, toEye, material);\n\
vec3 ambient = vec3(0.0);\n\
vec3 color = ambient + material.emission;\n\
color += material.diffuse * diffuse * czm_lightColor;\n\
color += material.specular * specular * czm_lightColor;\n\
return vec4(color, material.alpha);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_planeDistance = "float czm_planeDistance(vec4 plane, vec3 point) {\n\
return (dot(plane.xyz, point) + plane.w);\n\
}\n\
float czm_planeDistance(vec3 planeNormal, float planeDistance, vec3 point) {\n\
return (dot(planeNormal, point) + planeDistance);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_pointAlongRay = "vec3 czm_pointAlongRay(czm_ray ray, float time)\n\
{\n\
return ray.origin + (time * ray.direction);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_rayEllipsoidIntersectionInterval = "czm_raySegment czm_rayEllipsoidIntersectionInterval(czm_ray ray, vec3 ellipsoid_center, vec3 ellipsoid_inverseRadii)\n\
{\n\
vec3 q = ellipsoid_inverseRadii * (czm_inverseModelView * vec4(ray.origin, 1.0)).xyz;\n\
vec3 w = ellipsoid_inverseRadii * (czm_inverseModelView * vec4(ray.direction, 0.0)).xyz;\n\
q = q - ellipsoid_inverseRadii * (czm_inverseModelView * vec4(ellipsoid_center, 1.0)).xyz;\n\
float q2 = dot(q, q);\n\
float qw = dot(q, w);\n\
if (q2 > 1.0)\n\
{\n\
if (qw >= 0.0)\n\
{\n\
return czm_emptyRaySegment;\n\
}\n\
else\n\
{\n\
float qw2 = qw * qw;\n\
float difference = q2 - 1.0;\n\
float w2 = dot(w, w);\n\
float product = w2 * difference;\n\
if (qw2 < product)\n\
{\n\
return czm_emptyRaySegment;\n\
}\n\
else if (qw2 > product)\n\
{\n\
float discriminant = qw * qw - product;\n\
float temp = -qw + sqrt(discriminant);\n\
float root0 = temp / w2;\n\
float root1 = difference / temp;\n\
if (root0 < root1)\n\
{\n\
czm_raySegment i = czm_raySegment(root0, root1);\n\
return i;\n\
}\n\
else\n\
{\n\
czm_raySegment i = czm_raySegment(root1, root0);\n\
return i;\n\
}\n\
}\n\
else\n\
{\n\
float root = sqrt(difference / w2);\n\
czm_raySegment i = czm_raySegment(root, root);\n\
return i;\n\
}\n\
}\n\
}\n\
else if (q2 < 1.0)\n\
{\n\
float difference = q2 - 1.0;\n\
float w2 = dot(w, w);\n\
float product = w2 * difference;\n\
float discriminant = qw * qw - product;\n\
float temp = -qw + sqrt(discriminant);\n\
czm_raySegment i = czm_raySegment(0.0, temp / w2);\n\
return i;\n\
}\n\
else\n\
{\n\
if (qw < 0.0)\n\
{\n\
float w2 = dot(w, w);\n\
czm_raySegment i = czm_raySegment(0.0, -qw / w2);\n\
return i;\n\
}\n\
else\n\
{\n\
return czm_emptyRaySegment;\n\
}\n\
}\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_readDepth = "float czm_readDepth(sampler2D depthTexture, vec2 texCoords)\n\
{\n\
return czm_reverseLogDepth(texture2D(depthTexture, texCoords).r);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_readNonPerspective = "float czm_readNonPerspective(float value, float oneOverW) {\n\
return value * oneOverW;\n\
}\n\
vec2 czm_readNonPerspective(vec2 value, float oneOverW) {\n\
return value * oneOverW;\n\
}\n\
vec3 czm_readNonPerspective(vec3 value, float oneOverW) {\n\
return value * oneOverW;\n\
}\n\
vec4 czm_readNonPerspective(vec4 value, float oneOverW) {\n\
return value * oneOverW;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_reverseLogDepth = "float czm_reverseLogDepth(float logZ)\n\
{\n\
#ifdef LOG_DEPTH\n\
float near = czm_currentFrustum.x;\n\
float far = czm_currentFrustum.y;\n\
float log2Depth = logZ * czm_log2FarDepthFromNearPlusOne;\n\
float depthFromNear = pow(2.0, log2Depth) - 1.0;\n\
return far * (1.0 - near / (depthFromNear + near)) / (far - near);\n\
#endif\n\
return logZ;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_sampleOctahedralProjection = "vec3 czm_sampleOctahedralProjectionWithFiltering(sampler2D projectedMap, vec2 textureSize, vec3 direction, float lod)\n\
{\n\
direction /= dot(vec3(1.0), abs(direction));\n\
vec2 rev = abs(direction.zx) - vec2(1.0);\n\
vec2 neg = vec2(direction.x < 0.0 ? rev.x : -rev.x,\n\
direction.z < 0.0 ? rev.y : -rev.y);\n\
vec2 uv = direction.y < 0.0 ? neg : direction.xz;\n\
vec2 coord = 0.5 * uv + vec2(0.5);\n\
vec2 pixel = 1.0 / textureSize;\n\
if (lod > 0.0)\n\
{\n\
float scale = 1.0 / pow(2.0, lod);\n\
float offset = ((textureSize.y + 1.0) / textureSize.x);\n\
coord.x *= offset;\n\
coord *= scale;\n\
coord.x += offset + pixel.x;\n\
coord.y += (1.0 - (1.0 / pow(2.0, lod - 1.0))) + pixel.y * (lod - 1.0) * 2.0;\n\
}\n\
else\n\
{\n\
coord.x *= (textureSize.y / textureSize.x);\n\
}\n\
#ifndef OES_texture_float_linear\n\
vec3 color1 = texture2D(projectedMap, coord + vec2(0.0, pixel.y)).rgb;\n\
vec3 color2 = texture2D(projectedMap, coord + vec2(pixel.x, 0.0)).rgb;\n\
vec3 color3 = texture2D(projectedMap, coord + pixel).rgb;\n\
vec3 color4 = texture2D(projectedMap, coord).rgb;\n\
vec2 texturePosition = coord * textureSize;\n\
float fu = fract(texturePosition.x);\n\
float fv = fract(texturePosition.y);\n\
vec3 average1 = mix(color4, color2, fu);\n\
vec3 average2 = mix(color1, color3, fu);\n\
vec3 color = mix(average1, average2, fv);\n\
#else\n\
vec3 color = texture2D(projectedMap, coord).rgb;\n\
#endif\n\
return color;\n\
}\n\
vec3 czm_sampleOctahedralProjection(sampler2D projectedMap, vec2 textureSize, vec3 direction, float lod, float maxLod) {\n\
float currentLod = floor(lod + 0.5);\n\
float nextLod = min(currentLod + 1.0, maxLod);\n\
vec3 colorCurrentLod = czm_sampleOctahedralProjectionWithFiltering(projectedMap, textureSize, direction, currentLod);\n\
vec3 colorNextLod = czm_sampleOctahedralProjectionWithFiltering(projectedMap, textureSize, direction, nextLod);\n\
return mix(colorNextLod, colorCurrentLod, nextLod - lod);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_saturation = "vec3 czm_saturation(vec3 rgb, float adjustment)\n\
{\n\
const vec3 W = vec3(0.2125, 0.7154, 0.0721);\n\
vec3 intensity = vec3(dot(rgb, W));\n\
return mix(intensity, rgb, adjustment);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_shadowDepthCompare = "float czm_sampleShadowMap(samplerCube shadowMap, vec3 d)\n\
{\n\
return czm_unpackDepth(textureCube(shadowMap, d));\n\
}\n\
float czm_sampleShadowMap(sampler2D shadowMap, vec2 uv)\n\
{\n\
#ifdef USE_SHADOW_DEPTH_TEXTURE\n\
return texture2D(shadowMap, uv).r;\n\
#else\n\
return czm_unpackDepth(texture2D(shadowMap, uv));\n\
#endif\n\
}\n\
float czm_shadowDepthCompare(samplerCube shadowMap, vec3 uv, float depth)\n\
{\n\
return step(depth, czm_sampleShadowMap(shadowMap, uv));\n\
}\n\
float czm_shadowDepthCompare(sampler2D shadowMap, vec2 uv, float depth)\n\
{\n\
return step(depth, czm_sampleShadowMap(shadowMap, uv));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_shadowVisibility = "float czm_private_shadowVisibility(float visibility, float nDotL, float normalShadingSmooth, float darkness)\n\
{\n\
#ifdef USE_NORMAL_SHADING\n\
#ifdef USE_NORMAL_SHADING_SMOOTH\n\
float strength = clamp(nDotL / normalShadingSmooth, 0.0, 1.0);\n\
#else\n\
float strength = step(0.0, nDotL);\n\
#endif\n\
visibility *= strength;\n\
#endif\n\
visibility = max(visibility, darkness);\n\
return visibility;\n\
}\n\
#ifdef USE_CUBE_MAP_SHADOW\n\
float czm_shadowVisibility(samplerCube shadowMap, czm_shadowParameters shadowParameters)\n\
{\n\
float depthBias = shadowParameters.depthBias;\n\
float depth = shadowParameters.depth;\n\
float nDotL = shadowParameters.nDotL;\n\
float normalShadingSmooth = shadowParameters.normalShadingSmooth;\n\
float darkness = shadowParameters.darkness;\n\
vec3 uvw = shadowParameters.texCoords;\n\
depth -= depthBias;\n\
float visibility = czm_shadowDepthCompare(shadowMap, uvw, depth);\n\
return czm_private_shadowVisibility(visibility, nDotL, normalShadingSmooth, darkness);\n\
}\n\
#else\n\
float czm_shadowVisibility(sampler2D shadowMap, czm_shadowParameters shadowParameters)\n\
{\n\
float depthBias = shadowParameters.depthBias;\n\
float depth = shadowParameters.depth;\n\
float nDotL = shadowParameters.nDotL;\n\
float normalShadingSmooth = shadowParameters.normalShadingSmooth;\n\
float darkness = shadowParameters.darkness;\n\
vec2 uv = shadowParameters.texCoords;\n\
depth -= depthBias;\n\
#ifdef USE_SOFT_SHADOWS\n\
vec2 texelStepSize = shadowParameters.texelStepSize;\n\
float radius = 1.0;\n\
float dx0 = -texelStepSize.x * radius;\n\
float dy0 = -texelStepSize.y * radius;\n\
float dx1 = texelStepSize.x * radius;\n\
float dy1 = texelStepSize.y * radius;\n\
float visibility = (\n\
czm_shadowDepthCompare(shadowMap, uv, depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(dx0, dy0), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(0.0, dy0), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(dx1, dy0), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(dx0, 0.0), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(dx1, 0.0), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(dx0, dy1), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(0.0, dy1), depth) +\n\
czm_shadowDepthCompare(shadowMap, uv + vec2(dx1, dy1), depth)\n\
) * (1.0 / 9.0);\n\
#else\n\
float visibility = czm_shadowDepthCompare(shadowMap, uv, depth);\n\
#endif\n\
return czm_private_shadowVisibility(visibility, nDotL, normalShadingSmooth, darkness);\n\
}\n\
#endif\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_signNotZero = "float czm_signNotZero(float value)\n\
{\n\
return value >= 0.0 ? 1.0 : -1.0;\n\
}\n\
vec2 czm_signNotZero(vec2 value)\n\
{\n\
return vec2(czm_signNotZero(value.x), czm_signNotZero(value.y));\n\
}\n\
vec3 czm_signNotZero(vec3 value)\n\
{\n\
return vec3(czm_signNotZero(value.x), czm_signNotZero(value.y), czm_signNotZero(value.z));\n\
}\n\
vec4 czm_signNotZero(vec4 value)\n\
{\n\
return vec4(czm_signNotZero(value.x), czm_signNotZero(value.y), czm_signNotZero(value.z), czm_signNotZero(value.w));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_sphericalHarmonics = "vec3 czm_sphericalHarmonics(vec3 normal, vec3 coefficients[9])\n\
{\n\
const float c1 = 0.429043;\n\
const float c2 = 0.511664;\n\
const float c3 = 0.743125;\n\
const float c4 = 0.886227;\n\
const float c5 = 0.247708;\n\
vec3 L00 = coefficients[0];\n\
vec3 L1_1 = coefficients[1];\n\
vec3 L10 = coefficients[2];\n\
vec3 L11 = coefficients[3];\n\
vec3 L2_2 = coefficients[4];\n\
vec3 L2_1 = coefficients[5];\n\
vec3 L20 = coefficients[6];\n\
vec3 L21 = coefficients[7];\n\
vec3 L22 = coefficients[8];\n\
float x = normal.x;\n\
float y = normal.y;\n\
float z = normal.z;\n\
return c1 * L22 * (x * x - y * y) + c3 * L20 * z * z + c4 * L00 - c5 * L20 +\n\
2.0 * c1 * (L2_2 * x * y + L21 * x * z + L2_1 * y * z) +\n\
2.0 * c2 * (L11 * x + L1_1 * y + L10 * z);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_tangentToEyeSpaceMatrix = "mat3 czm_tangentToEyeSpaceMatrix(vec3 normalEC, vec3 tangentEC, vec3 bitangentEC)\n\
{\n\
vec3 normal = normalize(normalEC);\n\
vec3 tangent = normalize(tangentEC);\n\
vec3 bitangent = normalize(bitangentEC);\n\
return mat3(tangent.x  , tangent.y  , tangent.z,\n\
bitangent.x, bitangent.y, bitangent.z,\n\
normal.x   , normal.y   , normal.z);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_transformPlane = "vec4 czm_transformPlane(vec4 clippingPlane, mat4 transform) {\n\
vec3 transformedDirection = normalize((transform * vec4(clippingPlane.xyz, 0.0)).xyz);\n\
vec3 transformedPosition = (transform * vec4(clippingPlane.xyz * -clippingPlane.w, 1.0)).xyz;\n\
vec4 transformedPlane;\n\
transformedPlane.xyz = transformedDirection;\n\
transformedPlane.w = -dot(transformedDirection, transformedPosition);\n\
return transformedPlane;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_translateRelativeToEye = "vec4 czm_translateRelativeToEye(vec3 high, vec3 low)\n\
{\n\
vec3 highDifference = high - czm_encodedCameraPositionMCHigh;\n\
vec3 lowDifference = low - czm_encodedCameraPositionMCLow;\n\
return vec4(highDifference + lowDifference, 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_translucentPhong = "vec4 czm_translucentPhong(vec3 toEye, czm_material material, vec3 lightDirectionEC)\n\
{\n\
float diffuse = czm_getLambertDiffuse(vec3(0.0, 0.0, 1.0), material.normal);\n\
if (czm_sceneMode == czm_sceneMode3D) {\n\
diffuse += czm_getLambertDiffuse(vec3(0.0, 1.0, 0.0), material.normal);\n\
}\n\
diffuse = clamp(diffuse, 0.0, 1.0);\n\
float specular = czm_getSpecular(lightDirectionEC, toEye, material.normal, material.shininess);\n\
vec3 materialDiffuse = material.diffuse * 0.5;\n\
vec3 ambient = materialDiffuse;\n\
vec3 color = ambient + material.emission;\n\
color += materialDiffuse * diffuse * czm_lightColor;\n\
color += material.specular * specular * czm_lightColor;\n\
return vec4(color, material.alpha);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_transpose = "mat2 czm_transpose(mat2 matrix)\n\
{\n\
return mat2(\n\
matrix[0][0], matrix[1][0],\n\
matrix[0][1], matrix[1][1]);\n\
}\n\
mat3 czm_transpose(mat3 matrix)\n\
{\n\
return mat3(\n\
matrix[0][0], matrix[1][0], matrix[2][0],\n\
matrix[0][1], matrix[1][1], matrix[2][1],\n\
matrix[0][2], matrix[1][2], matrix[2][2]);\n\
}\n\
mat4 czm_transpose(mat4 matrix)\n\
{\n\
return mat4(\n\
matrix[0][0], matrix[1][0], matrix[2][0], matrix[3][0],\n\
matrix[0][1], matrix[1][1], matrix[2][1], matrix[3][1],\n\
matrix[0][2], matrix[1][2], matrix[2][2], matrix[3][2],\n\
matrix[0][3], matrix[1][3], matrix[2][3], matrix[3][3]);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_unpackDepth = "float czm_unpackDepth(vec4 packedDepth)\n\
{\n\
return dot(packedDepth, vec4(1.0, 1.0 / 255.0, 1.0 / 65025.0, 1.0 / 16581375.0));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_unpackFloat = "#define SHIFT_RIGHT_8 0.00390625 //1.0 / 256.0\n\
#define SHIFT_RIGHT_16 0.00001525878 //1.0 / 65536.0\n\
#define SHIFT_RIGHT_24 5.960464477539063e-8//1.0 / 16777216.0\n\
#define BIAS 38.0\n\
float czm_unpackFloat(vec4 packedFloat)\n\
{\n\
packedFloat *= 255.0;\n\
float temp = packedFloat.w / 2.0;\n\
float exponent = floor(temp);\n\
float sign = (temp - exponent) * 2.0;\n\
exponent = exponent - float(BIAS);\n\
sign = sign * 2.0 - 1.0;\n\
sign = -sign;\n\
float unpacked = sign * packedFloat.x * float(SHIFT_RIGHT_8);\n\
unpacked += sign * packedFloat.y * float(SHIFT_RIGHT_16);\n\
unpacked += sign * packedFloat.z * float(SHIFT_RIGHT_24);\n\
return unpacked * pow(10.0, exponent);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_vertexLogDepth = "#ifdef LOG_DEPTH\n\
varying float v_depthFromNearPlusOne;\n\
#ifdef SHADOW_MAP\n\
varying vec3 v_logPositionEC;\n\
#endif\n\
#endif\n\
vec4 czm_updatePositionDepth(vec4 coords) {\n\
#if defined(LOG_DEPTH)\n\
#ifdef SHADOW_MAP\n\
vec3 logPositionEC = (czm_inverseProjection * coords).xyz;\n\
v_logPositionEC = logPositionEC;\n\
#endif\n\
coords.z = clamp(coords.z / coords.w, -1.0, 1.0) * coords.w;\n\
#endif\n\
return coords;\n\
}\n\
void czm_vertexLogDepth()\n\
{\n\
#ifdef LOG_DEPTH\n\
v_depthFromNearPlusOne = (gl_Position.w - czm_currentFrustum.x) + 1.0;\n\
gl_Position = czm_updatePositionDepth(gl_Position);\n\
#endif\n\
}\n\
void czm_vertexLogDepth(vec4 clipCoords)\n\
{\n\
#ifdef LOG_DEPTH\n\
v_depthFromNearPlusOne = (clipCoords.w - czm_currentFrustum.x) + 1.0;\n\
czm_updatePositionDepth(clipCoords);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_windowToEyeCoordinates = "vec4 czm_windowToEyeCoordinates(vec4 fragmentCoordinate)\n\
{\n\
float x = 2.0 * (fragmentCoordinate.x - czm_viewport.x) / czm_viewport.z - 1.0;\n\
float y = 2.0 * (fragmentCoordinate.y - czm_viewport.y) / czm_viewport.w - 1.0;\n\
float z = (fragmentCoordinate.z - czm_viewportTransformation[3][2]) / czm_viewportTransformation[2][2];\n\
vec4 q = vec4(x, y, z, 1.0);\n\
q /= fragmentCoordinate.w;\n\
if (!(czm_inverseProjection == mat4(0.0)))\n\
{\n\
q = czm_inverseProjection * q;\n\
}\n\
else\n\
{\n\
float top = czm_frustumPlanes.x;\n\
float bottom = czm_frustumPlanes.y;\n\
float left = czm_frustumPlanes.z;\n\
float right = czm_frustumPlanes.w;\n\
float near = czm_currentFrustum.x;\n\
float far = czm_currentFrustum.y;\n\
q.x = (q.x * (right - left) + left + right) * 0.5;\n\
q.y = (q.y * (top - bottom) + bottom + top) * 0.5;\n\
q.z = (q.z * (near - far) - near - far) * 0.5;\n\
q.w = 1.0;\n\
}\n\
return q;\n\
}\n\
vec4 czm_windowToEyeCoordinates(vec2 fragmentCoordinateXY, float depthOrLogDepth)\n\
{\n\
#ifdef LOG_DEPTH\n\
float near = czm_currentFrustum.x;\n\
float far = czm_currentFrustum.y;\n\
float log2Depth = depthOrLogDepth * czm_log2FarDepthFromNearPlusOne;\n\
float depthFromNear = pow(2.0, log2Depth) - 1.0;\n\
float depthFromCamera = depthFromNear + near;\n\
vec4 windowCoord = vec4(fragmentCoordinateXY, far * (1.0 - near / depthFromCamera) / (far - near), 1.0);\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(windowCoord);\n\
eyeCoordinate.w = 1.0 / depthFromCamera;\n\
return eyeCoordinate;\n\
#else\n\
vec4 windowCoord = vec4(fragmentCoordinateXY, depthOrLogDepth, 1.0);\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(windowCoord);\n\
#endif\n\
return eyeCoordinate;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_writeDepthClamp = "#ifndef LOG_DEPTH\n\
varying float v_WindowZ;\n\
#endif\n\
void czm_writeDepthClamp()\n\
{\n\
#if defined(GL_EXT_frag_depth) && !defined(LOG_DEPTH)\n\
gl_FragDepthEXT = clamp(v_WindowZ * gl_FragCoord.w, 0.0, 1.0);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_writeLogDepth = "#ifdef LOG_DEPTH\n\
varying float v_depthFromNearPlusOne;\n\
#ifdef POLYGON_OFFSET\n\
uniform vec2 u_polygonOffset;\n\
#endif\n\
#endif\n\
void czm_writeLogDepth(float depth)\n\
{\n\
#if defined(GL_EXT_frag_depth) && defined(LOG_DEPTH)\n\
if (depth <= 0.9999999 || depth > czm_farDepthFromNearPlusOne) {\n\
discard;\n\
}\n\
#ifdef POLYGON_OFFSET\n\
float factor = u_polygonOffset[0];\n\
float units = u_polygonOffset[1];\n\
#ifdef GL_OES_standard_derivatives\n\
float x = dFdx(depth);\n\
float y = dFdy(depth);\n\
float m = sqrt(x * x + y * y);\n\
depth += m * factor;\n\
#endif\n\
#endif\n\
gl_FragDepthEXT = log2(depth) * czm_oneOverLog2FarDepthFromNearPlusOne;\n\
#ifdef POLYGON_OFFSET\n\
gl_FragDepthEXT += czm_epsilon7 * units;\n\
#endif\n\
#endif\n\
}\n\
void czm_writeLogDepth() {\n\
#ifdef LOG_DEPTH\n\
czm_writeLogDepth(v_depthFromNearPlusOne);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var czm_writeNonPerspective = "float czm_writeNonPerspective(float value, float w) {\n\
return value * w;\n\
}\n\
vec2 czm_writeNonPerspective(vec2 value, float w) {\n\
return value * w;\n\
}\n\
vec3 czm_writeNonPerspective(vec3 value, float w) {\n\
return value * w;\n\
}\n\
vec4 czm_writeNonPerspective(vec4 value, float w) {\n\
return value * w;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.

  var CzmBuiltins = {
      czm_degreesPerRadian : czm_degreesPerRadian,
      czm_depthRange : czm_depthRange,
      czm_epsilon1 : czm_epsilon1,
      czm_epsilon2 : czm_epsilon2,
      czm_epsilon3 : czm_epsilon3,
      czm_epsilon4 : czm_epsilon4,
      czm_epsilon5 : czm_epsilon5,
      czm_epsilon6 : czm_epsilon6,
      czm_epsilon7 : czm_epsilon7,
      czm_infinity : czm_infinity,
      czm_oneOverPi : czm_oneOverPi,
      czm_oneOverTwoPi : czm_oneOverTwoPi,
      czm_passCesium3DTile : czm_passCesium3DTile,
      czm_passCesium3DTileClassification : czm_passCesium3DTileClassification,
      czm_passCesium3DTileClassificationIgnoreShow : czm_passCesium3DTileClassificationIgnoreShow,
      czm_passClassification : czm_passClassification,
      czm_passCompute : czm_passCompute,
      czm_passEnvironment : czm_passEnvironment,
      czm_passGlobe : czm_passGlobe,
      czm_passOpaque : czm_passOpaque,
      czm_passOverlay : czm_passOverlay,
      czm_passTerrainClassification : czm_passTerrainClassification,
      czm_passTranslucent : czm_passTranslucent,
      czm_pi : czm_pi,
      czm_piOverFour : czm_piOverFour,
      czm_piOverSix : czm_piOverSix,
      czm_piOverThree : czm_piOverThree,
      czm_piOverTwo : czm_piOverTwo,
      czm_radiansPerDegree : czm_radiansPerDegree,
      czm_sceneMode2D : czm_sceneMode2D,
      czm_sceneMode3D : czm_sceneMode3D,
      czm_sceneModeColumbusView : czm_sceneModeColumbusView,
      czm_sceneModeMorphing : czm_sceneModeMorphing,
      czm_solarRadius : czm_solarRadius,
      czm_threePiOver2 : czm_threePiOver2,
      czm_twoPi : czm_twoPi,
      czm_webMercatorMaxLatitude : czm_webMercatorMaxLatitude,
      czm_depthRangeStruct : czm_depthRangeStruct,
      czm_material : czm_material,
      czm_materialInput : czm_materialInput,
      czm_ray : czm_ray,
      czm_raySegment : czm_raySegment,
      czm_shadowParameters : czm_shadowParameters,
      czm_HSBToRGB : czm_HSBToRGB,
      czm_HSLToRGB : czm_HSLToRGB,
      czm_RGBToHSB : czm_RGBToHSB,
      czm_RGBToHSL : czm_RGBToHSL,
      czm_RGBToXYZ : czm_RGBToXYZ,
      czm_XYZToRGB : czm_XYZToRGB,
      czm_acesTonemapping : czm_acesTonemapping,
      czm_alphaWeight : czm_alphaWeight,
      czm_antialias : czm_antialias,
      czm_approximateSphericalCoordinates : czm_approximateSphericalCoordinates,
      czm_backFacing : czm_backFacing,
      czm_branchFreeTernary : czm_branchFreeTernary,
      czm_cascadeColor : czm_cascadeColor,
      czm_cascadeDistance : czm_cascadeDistance,
      czm_cascadeMatrix : czm_cascadeMatrix,
      czm_cascadeWeights : czm_cascadeWeights,
      czm_columbusViewMorph : czm_columbusViewMorph,
      czm_computePosition : czm_computePosition,
      czm_cosineAndSine : czm_cosineAndSine,
      czm_decompressTextureCoordinates : czm_decompressTextureCoordinates,
      czm_depthClamp : czm_depthClamp,
      czm_eastNorthUpToEyeCoordinates : czm_eastNorthUpToEyeCoordinates,
      czm_ellipsoidContainsPoint : czm_ellipsoidContainsPoint,
      czm_ellipsoidWgs84TextureCoordinates : czm_ellipsoidWgs84TextureCoordinates,
      czm_equalsEpsilon : czm_equalsEpsilon,
      czm_eyeOffset : czm_eyeOffset,
      czm_eyeToWindowCoordinates : czm_eyeToWindowCoordinates,
      czm_fastApproximateAtan : czm_fastApproximateAtan,
      czm_fog : czm_fog,
      czm_gammaCorrect : czm_gammaCorrect,
      czm_geodeticSurfaceNormal : czm_geodeticSurfaceNormal,
      czm_getDefaultMaterial : czm_getDefaultMaterial,
      czm_getLambertDiffuse : czm_getLambertDiffuse,
      czm_getSpecular : czm_getSpecular,
      czm_getWaterNoise : czm_getWaterNoise,
      czm_hue : czm_hue,
      czm_inverseGamma : czm_inverseGamma,
      czm_isEmpty : czm_isEmpty,
      czm_isFull : czm_isFull,
      czm_latitudeToWebMercatorFraction : czm_latitudeToWebMercatorFraction,
      czm_lineDistance : czm_lineDistance,
      czm_luminance : czm_luminance,
      czm_metersPerPixel : czm_metersPerPixel,
      czm_modelToWindowCoordinates : czm_modelToWindowCoordinates,
      czm_multiplyWithColorBalance : czm_multiplyWithColorBalance,
      czm_nearFarScalar : czm_nearFarScalar,
      czm_octDecode : czm_octDecode,
      czm_packDepth : czm_packDepth,
      czm_phong : czm_phong,
      czm_planeDistance : czm_planeDistance,
      czm_pointAlongRay : czm_pointAlongRay,
      czm_rayEllipsoidIntersectionInterval : czm_rayEllipsoidIntersectionInterval,
      czm_readDepth : czm_readDepth,
      czm_readNonPerspective : czm_readNonPerspective,
      czm_reverseLogDepth : czm_reverseLogDepth,
      czm_sampleOctahedralProjection : czm_sampleOctahedralProjection,
      czm_saturation : czm_saturation,
      czm_shadowDepthCompare : czm_shadowDepthCompare,
      czm_shadowVisibility : czm_shadowVisibility,
      czm_signNotZero : czm_signNotZero,
      czm_sphericalHarmonics : czm_sphericalHarmonics,
      czm_tangentToEyeSpaceMatrix : czm_tangentToEyeSpaceMatrix,
      czm_transformPlane : czm_transformPlane,
      czm_translateRelativeToEye : czm_translateRelativeToEye,
      czm_translucentPhong : czm_translucentPhong,
      czm_transpose : czm_transpose,
      czm_unpackDepth : czm_unpackDepth,
      czm_unpackFloat : czm_unpackFloat,
      czm_vertexLogDepth : czm_vertexLogDepth,
      czm_windowToEyeCoordinates : czm_windowToEyeCoordinates,
      czm_writeDepthClamp : czm_writeDepthClamp,
      czm_writeLogDepth : czm_writeLogDepth,
      czm_writeNonPerspective : czm_writeNonPerspective
  };

  function removeComments(source) {
    // remove inline comments
    source = source.replace(/\/\/.*/g, "");
    // remove multiline comment block
    return source.replace(/\/\*\*[\s\S]*?\*\//gm, function (match) {
      // preserve the number of lines in the comment block so the line numbers will be correct when debugging shaders
      var numberOfLines = match.match(/\n/gm).length;
      var replacement = "";
      for (var lineNumber = 0; lineNumber < numberOfLines; ++lineNumber) {
        replacement += "\n";
      }
      return replacement;
    });
  }

  function getDependencyNode(name, glslSource, nodes) {
    var dependencyNode;

    // check if already loaded
    for (var i = 0; i < nodes.length; ++i) {
      if (nodes[i].name === name) {
        dependencyNode = nodes[i];
      }
    }

    if (!defined(dependencyNode)) {
      // strip doc comments so we don't accidentally try to determine a dependency for something found
      // in a comment
      glslSource = removeComments(glslSource);

      // create new node
      dependencyNode = {
        name: name,
        glslSource: glslSource,
        dependsOn: [],
        requiredBy: [],
        evaluated: false,
      };
      nodes.push(dependencyNode);
    }

    return dependencyNode;
  }

  function generateDependencies(currentNode, dependencyNodes) {
    if (currentNode.evaluated) {
      return;
    }

    currentNode.evaluated = true;

    // identify all dependencies that are referenced from this glsl source code
    var czmMatches = currentNode.glslSource.match(/\bczm_[a-zA-Z0-9_]*/g);
    if (defined(czmMatches) && czmMatches !== null) {
      // remove duplicates
      czmMatches = czmMatches.filter(function (elem, pos) {
        return czmMatches.indexOf(elem) === pos;
      });

      czmMatches.forEach(function (element) {
        if (
          element !== currentNode.name &&
          ShaderSource._czmBuiltinsAndUniforms.hasOwnProperty(element)
        ) {
          var referencedNode = getDependencyNode(
            element,
            ShaderSource._czmBuiltinsAndUniforms[element],
            dependencyNodes
          );
          currentNode.dependsOn.push(referencedNode);
          referencedNode.requiredBy.push(currentNode);

          // recursive call to find any dependencies of the new node
          generateDependencies(referencedNode, dependencyNodes);
        }
      });
    }
  }

  function sortDependencies(dependencyNodes) {
    var nodesWithoutIncomingEdges = [];
    var allNodes = [];

    while (dependencyNodes.length > 0) {
      var node = dependencyNodes.pop();
      allNodes.push(node);

      if (node.requiredBy.length === 0) {
        nodesWithoutIncomingEdges.push(node);
      }
    }

    while (nodesWithoutIncomingEdges.length > 0) {
      var currentNode = nodesWithoutIncomingEdges.shift();

      dependencyNodes.push(currentNode);

      for (var i = 0; i < currentNode.dependsOn.length; ++i) {
        // remove the edge from the graph
        var referencedNode = currentNode.dependsOn[i];
        var index = referencedNode.requiredBy.indexOf(currentNode);
        referencedNode.requiredBy.splice(index, 1);

        // if referenced node has no more incoming edges, add to list
        if (referencedNode.requiredBy.length === 0) {
          nodesWithoutIncomingEdges.push(referencedNode);
        }
      }
    }

    // if there are any nodes left with incoming edges, then there was a circular dependency somewhere in the graph
    var badNodes = [];
    for (var j = 0; j < allNodes.length; ++j) {
      if (allNodes[j].requiredBy.length !== 0) {
        badNodes.push(allNodes[j]);
      }
    }

    //>>includeStart('debug', pragmas.debug);
    if (badNodes.length !== 0) {
      var message =
        "A circular dependency was found in the following built-in functions/structs/constants: \n";
      for (var k = 0; k < badNodes.length; ++k) {
        message = message + badNodes[k].name + "\n";
      }
      throw new DeveloperError(message);
    }
    //>>includeEnd('debug');
  }

  function getBuiltinsAndAutomaticUniforms(shaderSource) {
    // generate a dependency graph for builtin functions
    var dependencyNodes = [];
    var root = getDependencyNode("main", shaderSource, dependencyNodes);
    generateDependencies(root, dependencyNodes);
    sortDependencies(dependencyNodes);

    // Concatenate the source code for the function dependencies.
    // Iterate in reverse so that dependent items are declared before they are used.
    var builtinsSource = "";
    for (var i = dependencyNodes.length - 1; i >= 0; --i) {
      builtinsSource = builtinsSource + dependencyNodes[i].glslSource + "\n";
    }

    return builtinsSource.replace(root.glslSource, "");
  }

  function combineShader(shaderSource, isFragmentShader, context) {
    var i;
    var length;

    // Combine shader sources, generally for pseudo-polymorphism, e.g., czm_getMaterial.
    var combinedSources = "";
    var sources = shaderSource.sources;
    if (defined(sources)) {
      for (i = 0, length = sources.length; i < length; ++i) {
        // #line needs to be on its own line.
        combinedSources += "\n#line 0\n" + sources[i];
      }
    }

    combinedSources = removeComments(combinedSources);

    // Extract existing shader version from sources
    var version;
    combinedSources = combinedSources.replace(/#version\s+(.*?)\n/gm, function (
      match,
      group1
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (defined(version) && version !== group1) {
        throw new DeveloperError(
          "inconsistent versions found: " + version + " and " + group1
        );
      }
      //>>includeEnd('debug');

      // Extract #version to put at the top
      version = group1;

      // Replace original #version directive with a new line so the line numbers
      // are not off by one.  There can be only one #version directive
      // and it must appear at the top of the source, only preceded by
      // whitespace and comments.
      return "\n";
    });

    // Extract shader extensions from sources
    var extensions = [];
    combinedSources = combinedSources.replace(/#extension.*\n/gm, function (
      match
    ) {
      // Extract extension to put at the top
      extensions.push(match);

      // Replace original #extension directive with a new line so the line numbers
      // are not off by one.
      return "\n";
    });

    // Remove precision qualifier
    combinedSources = combinedSources.replace(
      /precision\s(lowp|mediump|highp)\s(float|int);/,
      ""
    );

    // Replace main() for picked if desired.
    var pickColorQualifier = shaderSource.pickColorQualifier;
    if (defined(pickColorQualifier)) {
      combinedSources = ShaderSource.createPickFragmentShaderSource(
        combinedSources,
        pickColorQualifier
      );
    }

    // combine into single string
    var result = "";

    // #version must be first
    // defaults to #version 100 if not specified
    if (defined(version)) {
      result = "#version " + version + "\n";
    }

    var extensionsLength = extensions.length;
    for (i = 0; i < extensionsLength; i++) {
      result += extensions[i];
    }

    if (isFragmentShader) {
      result +=
        "\
#ifdef GL_FRAGMENT_PRECISION_HIGH\n\
    precision highp float;\n\
#else\n\
    precision mediump float;\n\
#endif\n\n";
    }

    // Prepend #defines for uber-shaders
    var defines = shaderSource.defines;
    if (defined(defines)) {
      for (i = 0, length = defines.length; i < length; ++i) {
        var define = defines[i];
        if (define.length !== 0) {
          result += "#define " + define + "\n";
        }
      }
    }

    // GLSLModernizer inserts its own layout qualifiers
    // at this position in the source
    if (context.webgl2) {
      result += "#define OUTPUT_DECLARATION\n\n";
    }

    // Define a constant for the OES_texture_float_linear extension since WebGL does not.
    if (context.textureFloatLinear) {
      result += "#define OES_texture_float_linear\n\n";
    }

    // append built-ins
    if (shaderSource.includeBuiltIns) {
      result += getBuiltinsAndAutomaticUniforms(combinedSources);
    }

    // reset line number
    result += "\n#line 0\n";

    // append actual source
    result += combinedSources;

    // modernize the source
    if (context.webgl2) {
      result = modernizeShader(result, isFragmentShader);
    }

    return result;
  }

  /**
   * An object containing various inputs that will be combined to form a final GLSL shader string.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {String[]} [options.sources] An array of strings to combine containing GLSL code for the shader.
   * @param {String[]} [options.defines] An array of strings containing GLSL identifiers to <code>#define</code>.
   * @param {String} [options.pickColorQualifier] The GLSL qualifier, <code>uniform</code> or <code>varying</code>, for the input <code>czm_pickColor</code>.  When defined, a pick fragment shader is generated.
   * @param {Boolean} [options.includeBuiltIns=true] If true, referenced built-in functions will be included with the combined shader.  Set to false if this shader will become a source in another shader, to avoid duplicating functions.
   *
   * @exception {DeveloperError} options.pickColorQualifier must be 'uniform' or 'varying'.
   *
   * @example
   * // 1. Prepend #defines to a shader
   * var source = new Cesium.ShaderSource({
   *   defines : ['WHITE'],
   *   sources : ['void main() { \n#ifdef WHITE\n gl_FragColor = vec4(1.0); \n#else\n gl_FragColor = vec4(0.0); \n#endif\n }']
   * });
   *
   * // 2. Modify a fragment shader for picking
   * var source = new Cesium.ShaderSource({
   *   sources : ['void main() { gl_FragColor = vec4(1.0); }'],
   *   pickColorQualifier : 'uniform'
   * });
   *
   * @private
   */
  function ShaderSource(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var pickColorQualifier = options.pickColorQualifier;

    //>>includeStart('debug', pragmas.debug);
    if (
      defined(pickColorQualifier) &&
      pickColorQualifier !== "uniform" &&
      pickColorQualifier !== "varying"
    ) {
      throw new DeveloperError(
        "options.pickColorQualifier must be 'uniform' or 'varying'."
      );
    }
    //>>includeEnd('debug');

    this.defines = defined(options.defines) ? options.defines.slice(0) : [];
    this.sources = defined(options.sources) ? options.sources.slice(0) : [];
    this.pickColorQualifier = pickColorQualifier;
    this.includeBuiltIns = defaultValue(options.includeBuiltIns, true);
  }

  ShaderSource.prototype.clone = function () {
    return new ShaderSource({
      sources: this.sources,
      defines: this.defines,
      pickColorQualifier: this.pickColorQualifier,
      includeBuiltIns: this.includeBuiltIns,
    });
  };

  ShaderSource.replaceMain = function (source, renamedMain) {
    renamedMain = "void " + renamedMain + "()";
    return source.replace(/void\s+main\s*\(\s*(?:void)?\s*\)/g, renamedMain);
  };

  /**
   * Create a single string containing the full, combined vertex shader with all dependencies and defines.
   *
   * @param {Context} context The current rendering context
   *
   * @returns {String} The combined shader string.
   */
  ShaderSource.prototype.createCombinedVertexShader = function (context) {
    return combineShader(this, false, context);
  };

  /**
   * Create a single string containing the full, combined fragment shader with all dependencies and defines.
   *
   * @param {Context} context The current rendering context
   *
   * @returns {String} The combined shader string.
   */
  ShaderSource.prototype.createCombinedFragmentShader = function (context) {
    return combineShader(this, true, context);
  };

  /**
   * For ShaderProgram testing
   * @private
   */
  ShaderSource._czmBuiltinsAndUniforms = {};

  // combine automatic uniforms and Cesium built-ins
  for (var builtinName in CzmBuiltins) {
    if (CzmBuiltins.hasOwnProperty(builtinName)) {
      ShaderSource._czmBuiltinsAndUniforms[builtinName] =
        CzmBuiltins[builtinName];
    }
  }
  for (var uniformName in AutomaticUniforms) {
    if (AutomaticUniforms.hasOwnProperty(uniformName)) {
      var uniform = AutomaticUniforms[uniformName];
      if (typeof uniform.getDeclaration === "function") {
        ShaderSource._czmBuiltinsAndUniforms[
          uniformName
        ] = uniform.getDeclaration(uniformName);
      }
    }
  }

  ShaderSource.createPickVertexShaderSource = function (vertexShaderSource) {
    var renamedVS = ShaderSource.replaceMain(vertexShaderSource, "czm_old_main");
    var pickMain =
      "attribute vec4 pickColor; \n" +
      "varying vec4 czm_pickColor; \n" +
      "void main() \n" +
      "{ \n" +
      "    czm_old_main(); \n" +
      "    czm_pickColor = pickColor; \n" +
      "}";

    return renamedVS + "\n" + pickMain;
  };

  ShaderSource.createPickFragmentShaderSource = function (
    fragmentShaderSource,
    pickColorQualifier
  ) {
    var renamedFS = ShaderSource.replaceMain(
      fragmentShaderSource,
      "czm_old_main"
    );
    var pickMain =
      pickColorQualifier +
      " vec4 czm_pickColor; \n" +
      "void main() \n" +
      "{ \n" +
      "    czm_old_main(); \n" +
      "    if (gl_FragColor.a == 0.0) { \n" +
      "       discard; \n" +
      "    } \n" +
      "    gl_FragColor = czm_pickColor; \n" +
      "}";

    return renamedFS + "\n" + pickMain;
  };

  ShaderSource.findVarying = function (shaderSource, names) {
    var sources = shaderSource.sources;

    var namesLength = names.length;
    for (var i = 0; i < namesLength; ++i) {
      var name = names[i];

      var sourcesLength = sources.length;
      for (var j = 0; j < sourcesLength; ++j) {
        if (sources[j].indexOf(name) !== -1) {
          return name;
        }
      }
    }

    return undefined;
  };

  var normalVaryingNames = ["v_normalEC", "v_normal"];

  ShaderSource.findNormalVarying = function (shaderSource) {
    return ShaderSource.findVarying(shaderSource, normalVaryingNames);
  };

  var positionVaryingNames = ["v_positionEC"];

  ShaderSource.findPositionVarying = function (shaderSource) {
    return ShaderSource.findVarying(shaderSource, positionVaryingNames);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var ShadowVolumeAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute float batchId;\n\
#ifdef EXTRUDED_GEOMETRY\n\
attribute vec3 extrudeDirection;\n\
uniform float u_globeMinimumAltitude;\n\
#endif // EXTRUDED_GEOMETRY\n\
#ifdef PER_INSTANCE_COLOR\n\
varying vec4 v_color;\n\
#endif // PER_INSTANCE_COLOR\n\
#ifdef TEXTURE_COORDINATES\n\
#ifdef SPHERICAL\n\
varying vec4 v_sphericalExtents;\n\
#else // SPHERICAL\n\
varying vec2 v_inversePlaneExtents;\n\
varying vec4 v_westPlane;\n\
varying vec4 v_southPlane;\n\
#endif // SPHERICAL\n\
varying vec3 v_uvMinAndSphericalLongitudeRotation;\n\
varying vec3 v_uMaxAndInverseDistance;\n\
varying vec3 v_vMaxAndInverseDistance;\n\
#endif // TEXTURE_COORDINATES\n\
void main()\n\
{\n\
vec4 position = czm_computePosition();\n\
#ifdef EXTRUDED_GEOMETRY\n\
float delta = min(u_globeMinimumAltitude, czm_geometricToleranceOverMeter * length(position.xyz));\n\
delta *= czm_sceneMode == czm_sceneMode3D ? 1.0 : 0.0;\n\
position = position + vec4(extrudeDirection * delta, 0.0);\n\
#endif\n\
#ifdef TEXTURE_COORDINATES\n\
#ifdef SPHERICAL\n\
v_sphericalExtents = czm_batchTable_sphericalExtents(batchId);\n\
v_uvMinAndSphericalLongitudeRotation.z = czm_batchTable_longitudeRotation(batchId);\n\
#else // SPHERICAL\n\
#ifdef COLUMBUS_VIEW_2D\n\
vec4 planes2D_high = czm_batchTable_planes2D_HIGH(batchId);\n\
vec4 planes2D_low = czm_batchTable_planes2D_LOW(batchId);\n\
vec2 idlSplitNewPlaneHiLow = vec2(EAST_MOST_X_HIGH - (WEST_MOST_X_HIGH - planes2D_high.w), EAST_MOST_X_LOW - (WEST_MOST_X_LOW - planes2D_low.w));\n\
bool idlSplit = planes2D_high.x > planes2D_high.w && position3DLow.y > 0.0;\n\
planes2D_high.w = czm_branchFreeTernary(idlSplit, idlSplitNewPlaneHiLow.x, planes2D_high.w);\n\
planes2D_low.w = czm_branchFreeTernary(idlSplit, idlSplitNewPlaneHiLow.y, planes2D_low.w);\n\
idlSplit = planes2D_high.x > planes2D_high.w && position3DLow.y < 0.0;\n\
idlSplitNewPlaneHiLow = vec2(WEST_MOST_X_HIGH - (EAST_MOST_X_HIGH - planes2D_high.x), WEST_MOST_X_LOW - (EAST_MOST_X_LOW - planes2D_low.x));\n\
planes2D_high.x = czm_branchFreeTernary(idlSplit, idlSplitNewPlaneHiLow.x, planes2D_high.x);\n\
planes2D_low.x = czm_branchFreeTernary(idlSplit, idlSplitNewPlaneHiLow.y, planes2D_low.x);\n\
vec3 southWestCorner = (czm_modelViewRelativeToEye * czm_translateRelativeToEye(vec3(0.0, planes2D_high.xy), vec3(0.0, planes2D_low.xy))).xyz;\n\
vec3 northWestCorner = (czm_modelViewRelativeToEye * czm_translateRelativeToEye(vec3(0.0, planes2D_high.x, planes2D_high.z), vec3(0.0, planes2D_low.x, planes2D_low.z))).xyz;\n\
vec3 southEastCorner = (czm_modelViewRelativeToEye * czm_translateRelativeToEye(vec3(0.0, planes2D_high.w, planes2D_high.y), vec3(0.0, planes2D_low.w, planes2D_low.y))).xyz;\n\
#else // COLUMBUS_VIEW_2D\n\
vec3 southWestCorner = (czm_modelViewRelativeToEye * czm_translateRelativeToEye(czm_batchTable_southWest_HIGH(batchId), czm_batchTable_southWest_LOW(batchId))).xyz;\n\
vec3 northWestCorner = czm_normal * czm_batchTable_northward(batchId) + southWestCorner;\n\
vec3 southEastCorner = czm_normal * czm_batchTable_eastward(batchId) + southWestCorner;\n\
#endif // COLUMBUS_VIEW_2D\n\
vec3 eastWard = southEastCorner - southWestCorner;\n\
float eastExtent = length(eastWard);\n\
eastWard /= eastExtent;\n\
vec3 northWard = northWestCorner - southWestCorner;\n\
float northExtent = length(northWard);\n\
northWard /= northExtent;\n\
v_westPlane = vec4(eastWard, -dot(eastWard, southWestCorner));\n\
v_southPlane = vec4(northWard, -dot(northWard, southWestCorner));\n\
v_inversePlaneExtents = vec2(1.0 / eastExtent, 1.0 / northExtent);\n\
#endif // SPHERICAL\n\
vec4 uvMinAndExtents = czm_batchTable_uvMinAndExtents(batchId);\n\
vec4 uMaxVmax = czm_batchTable_uMaxVmax(batchId);\n\
v_uMaxAndInverseDistance = vec3(uMaxVmax.xy, uvMinAndExtents.z);\n\
v_vMaxAndInverseDistance = vec3(uMaxVmax.zw, uvMinAndExtents.w);\n\
v_uvMinAndSphericalLongitudeRotation.xy = uvMinAndExtents.xy;\n\
#endif // TEXTURE_COORDINATES\n\
#ifdef PER_INSTANCE_COLOR\n\
v_color = czm_batchTable_color(batchId);\n\
#endif\n\
gl_Position = czm_depthClamp(czm_modelViewProjectionRelativeToEye * position);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ShadowVolumeFS = "#ifdef GL_EXT_frag_depth\n\
#extension GL_EXT_frag_depth : enable\n\
#endif\n\
#ifdef VECTOR_TILE\n\
uniform vec4 u_highlightColor;\n\
#endif\n\
void main(void)\n\
{\n\
#ifdef VECTOR_TILE\n\
gl_FragColor = czm_gammaCorrect(u_highlightColor);\n\
#else\n\
gl_FragColor = vec4(1.0);\n\
#endif\n\
czm_writeDepthClamp();\n\
}\n\
";

  /**
   * Whether a classification affects terrain, 3D Tiles or both.
   *
   * @enum {Number}
   */
  var ClassificationType = {
    /**
     * Only terrain will be classified.
     *
     * @type {Number}
     * @constant
     */
    TERRAIN: 0,
    /**
     * Only 3D Tiles will be classified.
     *
     * @type {Number}
     * @constant
     */
    CESIUM_3D_TILE: 1,
    /**
     * Both terrain and 3D Tiles will be classified.
     *
     * @type {Number}
     * @constant
     */
    BOTH: 2,
  };

  /**
   * @private
   */
  ClassificationType.NUMBER_OF_CLASSIFICATION_TYPES = 3;

  var ClassificationType$1 = Object.freeze(ClassificationType);

  /**
   * Determines the function used to compare two depths for the depth test.
   *
   * @enum {Number}
   */
  var DepthFunction = {
    /**
     * The depth test never passes.
     *
     * @type {Number}
     * @constant
     */
    NEVER: WebGLConstants$1.NEVER,

    /**
     * The depth test passes if the incoming depth is less than the stored depth.
     *
     * @type {Number}
     * @constant
     */
    LESS: WebGLConstants$1.LESS,

    /**
     * The depth test passes if the incoming depth is equal to the stored depth.
     *
     * @type {Number}
     * @constant
     */
    EQUAL: WebGLConstants$1.EQUAL,

    /**
     * The depth test passes if the incoming depth is less than or equal to the stored depth.
     *
     * @type {Number}
     * @constant
     */
    LESS_OR_EQUAL: WebGLConstants$1.LEQUAL,

    /**
     * The depth test passes if the incoming depth is greater than the stored depth.
     *
     * @type {Number}
     * @constant
     */
    GREATER: WebGLConstants$1.GREATER,

    /**
     * The depth test passes if the incoming depth is not equal to the stored depth.
     *
     * @type {Number}
     * @constant
     */
    NOT_EQUAL: WebGLConstants$1.NOTEQUAL,

    /**
     * The depth test passes if the incoming depth is greater than or equal to the stored depth.
     *
     * @type {Number}
     * @constant
     */
    GREATER_OR_EQUAL: WebGLConstants$1.GEQUAL,

    /**
     * The depth test always passes.
     *
     * @type {Number}
     * @constant
     */
    ALWAYS: WebGLConstants$1.ALWAYS,
  };
  var DepthFunction$1 = Object.freeze(DepthFunction);

  /**
   * @private
   */
  var BufferUsage = {
    STREAM_DRAW: WebGLConstants$1.STREAM_DRAW,
    STATIC_DRAW: WebGLConstants$1.STATIC_DRAW,
    DYNAMIC_DRAW: WebGLConstants$1.DYNAMIC_DRAW,

    validate: function (bufferUsage) {
      return (
        bufferUsage === BufferUsage.STREAM_DRAW ||
        bufferUsage === BufferUsage.STATIC_DRAW ||
        bufferUsage === BufferUsage.DYNAMIC_DRAW
      );
    },
  };
  var BufferUsage$1 = Object.freeze(BufferUsage);

  /**
   * @private
   */
  function Buffer$1(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);

    if (!defined(options.typedArray) && !defined(options.sizeInBytes)) {
      throw new DeveloperError(
        "Either options.sizeInBytes or options.typedArray is required."
      );
    }

    if (defined(options.typedArray) && defined(options.sizeInBytes)) {
      throw new DeveloperError(
        "Cannot pass in both options.sizeInBytes and options.typedArray."
      );
    }

    if (defined(options.typedArray)) {
      Check.typeOf.object("options.typedArray", options.typedArray);
      Check.typeOf.number(
        "options.typedArray.byteLength",
        options.typedArray.byteLength
      );
    }

    if (!BufferUsage$1.validate(options.usage)) {
      throw new DeveloperError("usage is invalid.");
    }
    //>>includeEnd('debug');

    var gl = options.context._gl;
    var bufferTarget = options.bufferTarget;
    var typedArray = options.typedArray;
    var sizeInBytes = options.sizeInBytes;
    var usage = options.usage;
    var hasArray = defined(typedArray);

    if (hasArray) {
      sizeInBytes = typedArray.byteLength;
    }

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThan("sizeInBytes", sizeInBytes, 0);
    //>>includeEnd('debug');

    var buffer = gl.createBuffer();
    gl.bindBuffer(bufferTarget, buffer);
    gl.bufferData(bufferTarget, hasArray ? typedArray : sizeInBytes, usage);
    gl.bindBuffer(bufferTarget, null);

    this._gl = gl;
    this._webgl2 = options.context._webgl2;
    this._bufferTarget = bufferTarget;
    this._sizeInBytes = sizeInBytes;
    this._usage = usage;
    this._buffer = buffer;
    this.vertexArrayDestroyable = true;
  }

  /**
   * Creates a vertex buffer, which contains untyped vertex data in GPU-controlled memory.
   * <br /><br />
   * A vertex array defines the actual makeup of a vertex, e.g., positions, normals, texture coordinates,
   * etc., by interpreting the raw data in one or more vertex buffers.
   *
   * @param {Object} options An object containing the following properties:
   * @param {Context} options.context The context in which to create the buffer
   * @param {ArrayBufferView} [options.typedArray] A typed array containing the data to copy to the buffer.
   * @param {Number} [options.sizeInBytes] A <code>Number</code> defining the size of the buffer in bytes. Required if options.typedArray is not given.
   * @param {BufferUsage} options.usage Specifies the expected usage pattern of the buffer. On some GL implementations, this can significantly affect performance. See {@link BufferUsage}.
   * @returns {VertexBuffer} The vertex buffer, ready to be attached to a vertex array.
   *
   * @exception {DeveloperError} Must specify either <options.typedArray> or <options.sizeInBytes>, but not both.
   * @exception {DeveloperError} The buffer size must be greater than zero.
   * @exception {DeveloperError} Invalid <code>usage</code>.
   *
   *
   * @example
   * // Example 1. Create a dynamic vertex buffer 16 bytes in size.
   * var buffer = Buffer.createVertexBuffer({
   *     context : context,
   *     sizeInBytes : 16,
   *     usage : BufferUsage.DYNAMIC_DRAW
   * });
   *
   * @example
   * // Example 2. Create a dynamic vertex buffer from three floating-point values.
   * // The data copied to the vertex buffer is considered raw bytes until it is
   * // interpreted as vertices using a vertex array.
   * var positionBuffer = buffer.createVertexBuffer({
   *     context : context,
   *     typedArray : new Float32Array([0, 0, 0]),
   *     usage : BufferUsage.STATIC_DRAW
   * });
   *
   * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGenBuffer.xml|glGenBuffer}
   * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glBindBuffer.xml|glBindBuffer} with <code>ARRAY_BUFFER</code>
   * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glBufferData.xml|glBufferData} with <code>ARRAY_BUFFER</code>
   */
  Buffer$1.createVertexBuffer = function (options) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    return new Buffer$1({
      context: options.context,
      bufferTarget: WebGLConstants$1.ARRAY_BUFFER,
      typedArray: options.typedArray,
      sizeInBytes: options.sizeInBytes,
      usage: options.usage,
    });
  };

  /**
   * Creates an index buffer, which contains typed indices in GPU-controlled memory.
   * <br /><br />
   * An index buffer can be attached to a vertex array to select vertices for rendering.
   * <code>Context.draw</code> can render using the entire index buffer or a subset
   * of the index buffer defined by an offset and count.
   *
   * @param {Object} options An object containing the following properties:
   * @param {Context} options.context The context in which to create the buffer
   * @param {ArrayBufferView} [options.typedArray] A typed array containing the data to copy to the buffer.
   * @param {Number} [options.sizeInBytes] A <code>Number</code> defining the size of the buffer in bytes. Required if options.typedArray is not given.
   * @param {BufferUsage} options.usage Specifies the expected usage pattern of the buffer. On some GL implementations, this can significantly affect performance. See {@link BufferUsage}.
   * @param {IndexDatatype} options.indexDatatype The datatype of indices in the buffer.
   * @returns {IndexBuffer} The index buffer, ready to be attached to a vertex array.
   *
   * @exception {DeveloperError} Must specify either <options.typedArray> or <options.sizeInBytes>, but not both.
   * @exception {DeveloperError} IndexDatatype.UNSIGNED_INT requires OES_element_index_uint, which is not supported on this system. Check context.elementIndexUint.
   * @exception {DeveloperError} The size in bytes must be greater than zero.
   * @exception {DeveloperError} Invalid <code>usage</code>.
   * @exception {DeveloperError} Invalid <code>indexDatatype</code>.
   *
   *
   * @example
   * // Example 1. Create a stream index buffer of unsigned shorts that is
   * // 16 bytes in size.
   * var buffer = Buffer.createIndexBuffer({
   *     context : context,
   *     sizeInBytes : 16,
   *     usage : BufferUsage.STREAM_DRAW,
   *     indexDatatype : IndexDatatype.UNSIGNED_SHORT
   * });
   *
   * @example
   * // Example 2. Create a static index buffer containing three unsigned shorts.
   * var buffer = Buffer.createIndexBuffer({
   *     context : context,
   *     typedArray : new Uint16Array([0, 1, 2]),
   *     usage : BufferUsage.STATIC_DRAW,
   *     indexDatatype : IndexDatatype.UNSIGNED_SHORT
   * });
   *
   * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGenBuffer.xml|glGenBuffer}
   * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glBindBuffer.xml|glBindBuffer} with <code>ELEMENT_ARRAY_BUFFER</code>
   * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glBufferData.xml|glBufferData} with <code>ELEMENT_ARRAY_BUFFER</code>
   */
  Buffer$1.createIndexBuffer = function (options) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);

    if (!IndexDatatype$1.validate(options.indexDatatype)) {
      throw new DeveloperError("Invalid indexDatatype.");
    }

    if (
      options.indexDatatype === IndexDatatype$1.UNSIGNED_INT &&
      !options.context.elementIndexUint
    ) {
      throw new DeveloperError(
        "IndexDatatype.UNSIGNED_INT requires OES_element_index_uint, which is not supported on this system.  Check context.elementIndexUint."
      );
    }
    //>>includeEnd('debug');

    var context = options.context;
    var indexDatatype = options.indexDatatype;

    var bytesPerIndex = IndexDatatype$1.getSizeInBytes(indexDatatype);
    var buffer = new Buffer$1({
      context: context,
      bufferTarget: WebGLConstants$1.ELEMENT_ARRAY_BUFFER,
      typedArray: options.typedArray,
      sizeInBytes: options.sizeInBytes,
      usage: options.usage,
    });

    var numberOfIndices = buffer.sizeInBytes / bytesPerIndex;

    Object.defineProperties(buffer, {
      indexDatatype: {
        get: function () {
          return indexDatatype;
        },
      },
      bytesPerIndex: {
        get: function () {
          return bytesPerIndex;
        },
      },
      numberOfIndices: {
        get: function () {
          return numberOfIndices;
        },
      },
    });

    return buffer;
  };

  Object.defineProperties(Buffer$1.prototype, {
    sizeInBytes: {
      get: function () {
        return this._sizeInBytes;
      },
    },

    usage: {
      get: function () {
        return this._usage;
      },
    },
  });

  Buffer$1.prototype._getBuffer = function () {
    return this._buffer;
  };

  Buffer$1.prototype.copyFromArrayView = function (arrayView, offsetInBytes) {
    offsetInBytes = defaultValue(offsetInBytes, 0);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("arrayView", arrayView);
    Check.typeOf.number.lessThanOrEquals(
      "offsetInBytes + arrayView.byteLength",
      offsetInBytes + arrayView.byteLength,
      this._sizeInBytes
    );
    //>>includeEnd('debug');

    var gl = this._gl;
    var target = this._bufferTarget;
    gl.bindBuffer(target, this._buffer);
    gl.bufferSubData(target, offsetInBytes, arrayView);
    gl.bindBuffer(target, null);
  };

  Buffer$1.prototype.copyFromBuffer = function (
    readBuffer,
    readOffset,
    writeOffset,
    sizeInBytes
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._webgl2) {
      throw new DeveloperError("A WebGL 2 context is required.");
    }
    if (!defined(readBuffer)) {
      throw new DeveloperError("readBuffer must be defined.");
    }
    if (!defined(sizeInBytes) || sizeInBytes <= 0) {
      throw new DeveloperError(
        "sizeInBytes must be defined and be greater than zero."
      );
    }
    if (
      !defined(readOffset) ||
      readOffset < 0 ||
      readOffset + sizeInBytes > readBuffer._sizeInBytes
    ) {
      throw new DeveloperError(
        "readOffset must be greater than or equal to zero and readOffset + sizeInBytes must be less than of equal to readBuffer.sizeInBytes."
      );
    }
    if (
      !defined(writeOffset) ||
      writeOffset < 0 ||
      writeOffset + sizeInBytes > this._sizeInBytes
    ) {
      throw new DeveloperError(
        "writeOffset must be greater than or equal to zero and writeOffset + sizeInBytes must be less than of equal to this.sizeInBytes."
      );
    }
    if (
      this._buffer === readBuffer._buffer &&
      ((writeOffset >= readOffset && writeOffset < readOffset + sizeInBytes) ||
        (readOffset > writeOffset && readOffset < writeOffset + sizeInBytes))
    ) {
      throw new DeveloperError(
        "When readBuffer is equal to this, the ranges [readOffset + sizeInBytes) and [writeOffset, writeOffset + sizeInBytes) must not overlap."
      );
    }
    if (
      (this._bufferTarget === WebGLConstants$1.ELEMENT_ARRAY_BUFFER &&
        readBuffer._bufferTarget !== WebGLConstants$1.ELEMENT_ARRAY_BUFFER) ||
      (this._bufferTarget !== WebGLConstants$1.ELEMENT_ARRAY_BUFFER &&
        readBuffer._bufferTarget === WebGLConstants$1.ELEMENT_ARRAY_BUFFER)
    ) {
      throw new DeveloperError(
        "Can not copy an index buffer into another buffer type."
      );
    }
    //>>includeEnd('debug');

    var readTarget = WebGLConstants$1.COPY_READ_BUFFER;
    var writeTarget = WebGLConstants$1.COPY_WRITE_BUFFER;

    var gl = this._gl;
    gl.bindBuffer(writeTarget, this._buffer);
    gl.bindBuffer(readTarget, readBuffer._buffer);
    gl.copyBufferSubData(
      readTarget,
      writeTarget,
      readOffset,
      writeOffset,
      sizeInBytes
    );
    gl.bindBuffer(writeTarget, null);
    gl.bindBuffer(readTarget, null);
  };

  Buffer$1.prototype.getBufferData = function (
    arrayView,
    sourceOffset,
    destinationOffset,
    length
  ) {
    sourceOffset = defaultValue(sourceOffset, 0);
    destinationOffset = defaultValue(destinationOffset, 0);

    //>>includeStart('debug', pragmas.debug);
    if (!this._webgl2) {
      throw new DeveloperError("A WebGL 2 context is required.");
    }
    if (!defined(arrayView)) {
      throw new DeveloperError("arrayView is required.");
    }

    var copyLength;
    var elementSize;
    var arrayLength = arrayView.byteLength;
    if (!defined(length)) {
      if (defined(arrayLength)) {
        copyLength = arrayLength - destinationOffset;
        elementSize = 1;
      } else {
        arrayLength = arrayView.length;
        copyLength = arrayLength - destinationOffset;
        elementSize = arrayView.BYTES_PER_ELEMENT;
      }
    } else {
      copyLength = length;
      if (defined(arrayLength)) {
        elementSize = 1;
      } else {
        arrayLength = arrayView.length;
        elementSize = arrayView.BYTES_PER_ELEMENT;
      }
    }

    if (destinationOffset < 0 || destinationOffset > arrayLength) {
      throw new DeveloperError(
        "destinationOffset must be greater than zero and less than the arrayView length."
      );
    }
    if (destinationOffset + copyLength > arrayLength) {
      throw new DeveloperError(
        "destinationOffset + length must be less than or equal to the arrayViewLength."
      );
    }
    if (sourceOffset < 0 || sourceOffset > this._sizeInBytes) {
      throw new DeveloperError(
        "sourceOffset must be greater than zero and less than the buffers size."
      );
    }
    if (sourceOffset + copyLength * elementSize > this._sizeInBytes) {
      throw new DeveloperError(
        "sourceOffset + length must be less than the buffers size."
      );
    }
    //>>includeEnd('debug');

    var gl = this._gl;
    var target = WebGLConstants$1.COPY_READ_BUFFER;
    gl.bindBuffer(target, this._buffer);
    gl.getBufferSubData(
      target,
      sourceOffset,
      arrayView,
      destinationOffset,
      length
    );
    gl.bindBuffer(target, null);
  };

  Buffer$1.prototype.isDestroyed = function () {
    return false;
  };

  Buffer$1.prototype.destroy = function () {
    this._gl.deleteBuffer(this._buffer);
    return destroyObject(this);
  };

  function addAttribute(attributes, attribute, index, context) {
    var hasVertexBuffer = defined(attribute.vertexBuffer);
    var hasValue = defined(attribute.value);
    var componentsPerAttribute = attribute.value
      ? attribute.value.length
      : attribute.componentsPerAttribute;

    //>>includeStart('debug', pragmas.debug);
    if (!hasVertexBuffer && !hasValue) {
      throw new DeveloperError("attribute must have a vertexBuffer or a value.");
    }
    if (hasVertexBuffer && hasValue) {
      throw new DeveloperError(
        "attribute cannot have both a vertexBuffer and a value.  It must have either a vertexBuffer property defining per-vertex data or a value property defining data for all vertices."
      );
    }
    if (
      componentsPerAttribute !== 1 &&
      componentsPerAttribute !== 2 &&
      componentsPerAttribute !== 3 &&
      componentsPerAttribute !== 4
    ) {
      if (hasValue) {
        throw new DeveloperError(
          "attribute.value.length must be in the range [1, 4]."
        );
      }

      throw new DeveloperError(
        "attribute.componentsPerAttribute must be in the range [1, 4]."
      );
    }
    if (
      defined(attribute.componentDatatype) &&
      !ComponentDatatype$1.validate(attribute.componentDatatype)
    ) {
      throw new DeveloperError(
        "attribute must have a valid componentDatatype or not specify it."
      );
    }
    if (defined(attribute.strideInBytes) && attribute.strideInBytes > 255) {
      // WebGL limit.  Not in GL ES.
      throw new DeveloperError(
        "attribute must have a strideInBytes less than or equal to 255 or not specify it."
      );
    }
    if (
      defined(attribute.instanceDivisor) &&
      attribute.instanceDivisor > 0 &&
      !context.instancedArrays
    ) {
      throw new DeveloperError("instanced arrays is not supported");
    }
    if (defined(attribute.instanceDivisor) && attribute.instanceDivisor < 0) {
      throw new DeveloperError(
        "attribute must have an instanceDivisor greater than or equal to zero"
      );
    }
    if (defined(attribute.instanceDivisor) && hasValue) {
      throw new DeveloperError(
        "attribute cannot have have an instanceDivisor if it is not backed by a buffer"
      );
    }
    if (
      defined(attribute.instanceDivisor) &&
      attribute.instanceDivisor > 0 &&
      attribute.index === 0
    ) {
      throw new DeveloperError(
        "attribute zero cannot have an instanceDivisor greater than 0"
      );
    }
    //>>includeEnd('debug');

    // Shallow copy the attribute; we do not want to copy the vertex buffer.
    var attr = {
      index: defaultValue(attribute.index, index),
      enabled: defaultValue(attribute.enabled, true),
      vertexBuffer: attribute.vertexBuffer,
      value: hasValue ? attribute.value.slice(0) : undefined,
      componentsPerAttribute: componentsPerAttribute,
      componentDatatype: defaultValue(
        attribute.componentDatatype,
        ComponentDatatype$1.FLOAT
      ),
      normalize: defaultValue(attribute.normalize, false),
      offsetInBytes: defaultValue(attribute.offsetInBytes, 0),
      strideInBytes: defaultValue(attribute.strideInBytes, 0),
      instanceDivisor: defaultValue(attribute.instanceDivisor, 0),
    };

    if (hasVertexBuffer) {
      // Common case: vertex buffer for per-vertex data
      attr.vertexAttrib = function (gl) {
        var index = this.index;
        gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer._getBuffer());
        gl.vertexAttribPointer(
          index,
          this.componentsPerAttribute,
          this.componentDatatype,
          this.normalize,
          this.strideInBytes,
          this.offsetInBytes
        );
        gl.enableVertexAttribArray(index);
        if (this.instanceDivisor > 0) {
          context.glVertexAttribDivisor(index, this.instanceDivisor);
          context._vertexAttribDivisors[index] = this.instanceDivisor;
          context._previousDrawInstanced = true;
        }
      };

      attr.disableVertexAttribArray = function (gl) {
        gl.disableVertexAttribArray(this.index);
        if (this.instanceDivisor > 0) {
          context.glVertexAttribDivisor(index, 0);
        }
      };
    } else {
      // Less common case: value array for the same data for each vertex
      switch (attr.componentsPerAttribute) {
        case 1:
          attr.vertexAttrib = function (gl) {
            gl.vertexAttrib1fv(this.index, this.value);
          };
          break;
        case 2:
          attr.vertexAttrib = function (gl) {
            gl.vertexAttrib2fv(this.index, this.value);
          };
          break;
        case 3:
          attr.vertexAttrib = function (gl) {
            gl.vertexAttrib3fv(this.index, this.value);
          };
          break;
        case 4:
          attr.vertexAttrib = function (gl) {
            gl.vertexAttrib4fv(this.index, this.value);
          };
          break;
      }

      attr.disableVertexAttribArray = function (gl) {};
    }

    attributes.push(attr);
  }

  function bind(gl, attributes, indexBuffer) {
    for (var i = 0; i < attributes.length; ++i) {
      var attribute = attributes[i];
      if (attribute.enabled) {
        attribute.vertexAttrib(gl);
      }
    }

    if (defined(indexBuffer)) {
      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer._getBuffer());
    }
  }

  /**
   * Creates a vertex array, which defines the attributes making up a vertex, and contains an optional index buffer
   * to select vertices for rendering.  Attributes are defined using object literals as shown in Example 1 below.
   *
   * @param {Object} options Object with the following properties:
   * @param {Context} options.context The context in which the VertexArray gets created.
   * @param {Object[]} options.attributes An array of attributes.
   * @param {IndexBuffer} [options.indexBuffer] An optional index buffer.
   *
   * @returns {VertexArray} The vertex array, ready for use with drawing.
   *
   * @exception {DeveloperError} Attribute must have a <code>vertexBuffer</code>.
   * @exception {DeveloperError} Attribute must have a <code>componentsPerAttribute</code>.
   * @exception {DeveloperError} Attribute must have a valid <code>componentDatatype</code> or not specify it.
   * @exception {DeveloperError} Attribute must have a <code>strideInBytes</code> less than or equal to 255 or not specify it.
   * @exception {DeveloperError} Index n is used by more than one attribute.
   *
   *
   * @example
   * // Example 1. Create a vertex array with vertices made up of three floating point
   * // values, e.g., a position, from a single vertex buffer.  No index buffer is used.
   * var positionBuffer = Buffer.createVertexBuffer({
   *     context : context,
   *     sizeInBytes : 12,
   *     usage : BufferUsage.STATIC_DRAW
   * });
   * var attributes = [
   *     {
   *         index                  : 0,
   *         enabled                : true,
   *         vertexBuffer           : positionBuffer,
   *         componentsPerAttribute : 3,
   *         componentDatatype      : ComponentDatatype.FLOAT,
   *         normalize              : false,
   *         offsetInBytes          : 0,
   *         strideInBytes          : 0 // tightly packed
   *         instanceDivisor        : 0 // not instanced
   *     }
   * ];
   * var va = new VertexArray({
   *     context : context,
   *     attributes : attributes
   * });
   *
   * @example
   * // Example 2. Create a vertex array with vertices from two different vertex buffers.
   * // Each vertex has a three-component position and three-component normal.
   * var positionBuffer = Buffer.createVertexBuffer({
   *     context : context,
   *     sizeInBytes : 12,
   *     usage : BufferUsage.STATIC_DRAW
   * });
   * var normalBuffer = Buffer.createVertexBuffer({
   *     context : context,
   *     sizeInBytes : 12,
   *     usage : BufferUsage.STATIC_DRAW
   * });
   * var attributes = [
   *     {
   *         index                  : 0,
   *         vertexBuffer           : positionBuffer,
   *         componentsPerAttribute : 3,
   *         componentDatatype      : ComponentDatatype.FLOAT
   *     },
   *     {
   *         index                  : 1,
   *         vertexBuffer           : normalBuffer,
   *         componentsPerAttribute : 3,
   *         componentDatatype      : ComponentDatatype.FLOAT
   *     }
   * ];
   * var va = new VertexArray({
   *     context : context,
   *     attributes : attributes
   * });
   *
   * @example
   * // Example 3. Creates the same vertex layout as Example 2 using a single
   * // vertex buffer, instead of two.
   * var buffer = Buffer.createVertexBuffer({
   *     context : context,
   *     sizeInBytes : 24,
   *     usage : BufferUsage.STATIC_DRAW
   * });
   * var attributes = [
   *     {
   *         vertexBuffer           : buffer,
   *         componentsPerAttribute : 3,
   *         componentDatatype      : ComponentDatatype.FLOAT,
   *         offsetInBytes          : 0,
   *         strideInBytes          : 24
   *     },
   *     {
   *         vertexBuffer           : buffer,
   *         componentsPerAttribute : 3,
   *         componentDatatype      : ComponentDatatype.FLOAT,
   *         normalize              : true,
   *         offsetInBytes          : 12,
   *         strideInBytes          : 24
   *     }
   * ];
   * var va = new VertexArray({
   *     context : context,
   *     attributes : attributes
   * });
   *
   * @see Buffer#createVertexBuffer
   * @see Buffer#createIndexBuffer
   * @see Context#draw
   *
   * @private
   */
  function VertexArray(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    Check.defined("options.attributes", options.attributes);
    //>>includeEnd('debug');

    var context = options.context;
    var gl = context._gl;
    var attributes = options.attributes;
    var indexBuffer = options.indexBuffer;

    var i;
    var vaAttributes = [];
    var numberOfVertices = 1; // if every attribute is backed by a single value
    var hasInstancedAttributes = false;
    var hasConstantAttributes = false;

    var length = attributes.length;
    for (i = 0; i < length; ++i) {
      addAttribute(vaAttributes, attributes[i], i, context);
    }

    length = vaAttributes.length;
    for (i = 0; i < length; ++i) {
      var attribute = vaAttributes[i];

      if (defined(attribute.vertexBuffer) && attribute.instanceDivisor === 0) {
        // This assumes that each vertex buffer in the vertex array has the same number of vertices.
        var bytes =
          attribute.strideInBytes ||
          attribute.componentsPerAttribute *
            ComponentDatatype$1.getSizeInBytes(attribute.componentDatatype);
        numberOfVertices = attribute.vertexBuffer.sizeInBytes / bytes;
        break;
      }
    }

    for (i = 0; i < length; ++i) {
      if (vaAttributes[i].instanceDivisor > 0) {
        hasInstancedAttributes = true;
      }
      if (defined(vaAttributes[i].value)) {
        hasConstantAttributes = true;
      }
    }

    //>>includeStart('debug', pragmas.debug);
    // Verify all attribute names are unique
    var uniqueIndices = {};
    for (i = 0; i < length; ++i) {
      var index = vaAttributes[i].index;
      if (uniqueIndices[index]) {
        throw new DeveloperError(
          "Index " + index + " is used by more than one attribute."
        );
      }
      uniqueIndices[index] = true;
    }
    //>>includeEnd('debug');

    var vao;

    // Setup VAO if supported
    if (context.vertexArrayObject) {
      vao = context.glCreateVertexArray();
      context.glBindVertexArray(vao);
      bind(gl, vaAttributes, indexBuffer);
      context.glBindVertexArray(null);
    }

    this._numberOfVertices = numberOfVertices;
    this._hasInstancedAttributes = hasInstancedAttributes;
    this._hasConstantAttributes = hasConstantAttributes;
    this._context = context;
    this._gl = gl;
    this._vao = vao;
    this._attributes = vaAttributes;
    this._indexBuffer = indexBuffer;
  }

  function computeNumberOfVertices(attribute) {
    return attribute.values.length / attribute.componentsPerAttribute;
  }

  function computeAttributeSizeInBytes(attribute) {
    return (
      ComponentDatatype$1.getSizeInBytes(attribute.componentDatatype) *
      attribute.componentsPerAttribute
    );
  }

  function interleaveAttributes(attributes) {
    var j;
    var name;
    var attribute;

    // Extract attribute names.
    var names = [];
    for (name in attributes) {
      // Attribute needs to have per-vertex values; not a constant value for all vertices.
      if (
        attributes.hasOwnProperty(name) &&
        defined(attributes[name]) &&
        defined(attributes[name].values)
      ) {
        names.push(name);

        if (attributes[name].componentDatatype === ComponentDatatype$1.DOUBLE) {
          attributes[name].componentDatatype = ComponentDatatype$1.FLOAT;
          attributes[name].values = ComponentDatatype$1.createTypedArray(
            ComponentDatatype$1.FLOAT,
            attributes[name].values
          );
        }
      }
    }

    // Validation.  Compute number of vertices.
    var numberOfVertices;
    var namesLength = names.length;

    if (namesLength > 0) {
      numberOfVertices = computeNumberOfVertices(attributes[names[0]]);

      for (j = 1; j < namesLength; ++j) {
        var currentNumberOfVertices = computeNumberOfVertices(
          attributes[names[j]]
        );

        if (currentNumberOfVertices !== numberOfVertices) {
          throw new RuntimeError(
            "Each attribute list must have the same number of vertices.  " +
              "Attribute " +
              names[j] +
              " has a different number of vertices " +
              "(" +
              currentNumberOfVertices.toString() +
              ")" +
              " than attribute " +
              names[0] +
              " (" +
              numberOfVertices.toString() +
              ")."
          );
        }
      }
    }

    // Sort attributes by the size of their components.  From left to right, a vertex stores floats, shorts, and then bytes.
    names.sort(function (left, right) {
      return (
        ComponentDatatype$1.getSizeInBytes(attributes[right].componentDatatype) -
        ComponentDatatype$1.getSizeInBytes(attributes[left].componentDatatype)
      );
    });

    // Compute sizes and strides.
    var vertexSizeInBytes = 0;
    var offsetsInBytes = {};

    for (j = 0; j < namesLength; ++j) {
      name = names[j];
      attribute = attributes[name];

      offsetsInBytes[name] = vertexSizeInBytes;
      vertexSizeInBytes += computeAttributeSizeInBytes(attribute);
    }

    if (vertexSizeInBytes > 0) {
      // Pad each vertex to be a multiple of the largest component datatype so each
      // attribute can be addressed using typed arrays.
      var maxComponentSizeInBytes = ComponentDatatype$1.getSizeInBytes(
        attributes[names[0]].componentDatatype
      ); // Sorted large to small
      var remainder = vertexSizeInBytes % maxComponentSizeInBytes;
      if (remainder !== 0) {
        vertexSizeInBytes += maxComponentSizeInBytes - remainder;
      }

      // Total vertex buffer size in bytes, including per-vertex padding.
      var vertexBufferSizeInBytes = numberOfVertices * vertexSizeInBytes;

      // Create array for interleaved vertices.  Each attribute has a different view (pointer) into the array.
      var buffer = new ArrayBuffer(vertexBufferSizeInBytes);
      var views = {};

      for (j = 0; j < namesLength; ++j) {
        name = names[j];
        var sizeInBytes = ComponentDatatype$1.getSizeInBytes(
          attributes[name].componentDatatype
        );

        views[name] = {
          pointer: ComponentDatatype$1.createTypedArray(
            attributes[name].componentDatatype,
            buffer
          ),
          index: offsetsInBytes[name] / sizeInBytes, // Offset in ComponentType
          strideInComponentType: vertexSizeInBytes / sizeInBytes,
        };
      }

      // Copy attributes into one interleaved array.
      // PERFORMANCE_IDEA:  Can we optimize these loops?
      for (j = 0; j < numberOfVertices; ++j) {
        for (var n = 0; n < namesLength; ++n) {
          name = names[n];
          attribute = attributes[name];
          var values = attribute.values;
          var view = views[name];
          var pointer = view.pointer;

          var numberOfComponents = attribute.componentsPerAttribute;
          for (var k = 0; k < numberOfComponents; ++k) {
            pointer[view.index + k] = values[j * numberOfComponents + k];
          }

          view.index += view.strideInComponentType;
        }
      }

      return {
        buffer: buffer,
        offsetsInBytes: offsetsInBytes,
        vertexSizeInBytes: vertexSizeInBytes,
      };
    }

    // No attributes to interleave.
    return undefined;
  }

  /**
   * Creates a vertex array from a geometry.  A geometry contains vertex attributes and optional index data
   * in system memory, whereas a vertex array contains vertex buffers and an optional index buffer in WebGL
   * memory for use with rendering.
   * <br /><br />
   * The <code>geometry</code> argument should use the standard layout like the geometry returned by {@link BoxGeometry}.
   * <br /><br />
   * <code>options</code> can have four properties:
   * <ul>
   *   <li><code>geometry</code>:  The source geometry containing data used to create the vertex array.</li>
   *   <li><code>attributeLocations</code>:  An object that maps geometry attribute names to vertex shader attribute locations.</li>
   *   <li><code>bufferUsage</code>:  The expected usage pattern of the vertex array's buffers.  On some WebGL implementations, this can significantly affect performance.  See {@link BufferUsage}.  Default: <code>BufferUsage.DYNAMIC_DRAW</code>.</li>
   *   <li><code>interleave</code>:  Determines if all attributes are interleaved in a single vertex buffer or if each attribute is stored in a separate vertex buffer.  Default: <code>false</code>.</li>
   * </ul>
   * <br />
   * If <code>options</code> is not specified or the <code>geometry</code> contains no data, the returned vertex array is empty.
   *
   * @param {Object} options An object defining the geometry, attribute indices, buffer usage, and vertex layout used to create the vertex array.
   *
   * @exception {RuntimeError} Each attribute list must have the same number of vertices.
   * @exception {DeveloperError} The geometry must have zero or one index lists.
   * @exception {DeveloperError} Index n is used by more than one attribute.
   *
   *
   * @example
   * // Example 1. Creates a vertex array for rendering a box.  The default dynamic draw
   * // usage is used for the created vertex and index buffer.  The attributes are not
   * // interleaved by default.
   * var geometry = new BoxGeometry();
   * var va = VertexArray.fromGeometry({
   *     context            : context,
   *     geometry           : geometry,
   *     attributeLocations : GeometryPipeline.createAttributeLocations(geometry),
   * });
   *
   * @example
   * // Example 2. Creates a vertex array with interleaved attributes in a
   * // single vertex buffer.  The vertex and index buffer have static draw usage.
   * var va = VertexArray.fromGeometry({
   *     context            : context,
   *     geometry           : geometry,
   *     attributeLocations : GeometryPipeline.createAttributeLocations(geometry),
   *     bufferUsage        : BufferUsage.STATIC_DRAW,
   *     interleave         : true
   * });
   *
   * @example
   * // Example 3.  When the caller destroys the vertex array, it also destroys the
   * // attached vertex buffer(s) and index buffer.
   * va = va.destroy();
   *
   * @see Buffer#createVertexBuffer
   * @see Buffer#createIndexBuffer
   * @see GeometryPipeline.createAttributeLocations
   * @see ShaderProgram
   */
  VertexArray.fromGeometry = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    var context = options.context;
    var geometry = defaultValue(options.geometry, defaultValue.EMPTY_OBJECT);

    var bufferUsage = defaultValue(options.bufferUsage, BufferUsage$1.DYNAMIC_DRAW);

    var attributeLocations = defaultValue(
      options.attributeLocations,
      defaultValue.EMPTY_OBJECT
    );
    var interleave = defaultValue(options.interleave, false);
    var createdVAAttributes = options.vertexArrayAttributes;

    var name;
    var attribute;
    var vertexBuffer;
    var vaAttributes = defined(createdVAAttributes) ? createdVAAttributes : [];
    var attributes = geometry.attributes;

    if (interleave) {
      // Use a single vertex buffer with interleaved vertices.
      var interleavedAttributes = interleaveAttributes(attributes);
      if (defined(interleavedAttributes)) {
        vertexBuffer = Buffer$1.createVertexBuffer({
          context: context,
          typedArray: interleavedAttributes.buffer,
          usage: bufferUsage,
        });
        var offsetsInBytes = interleavedAttributes.offsetsInBytes;
        var strideInBytes = interleavedAttributes.vertexSizeInBytes;

        for (name in attributes) {
          if (attributes.hasOwnProperty(name) && defined(attributes[name])) {
            attribute = attributes[name];

            if (defined(attribute.values)) {
              // Common case: per-vertex attributes
              vaAttributes.push({
                index: attributeLocations[name],
                vertexBuffer: vertexBuffer,
                componentDatatype: attribute.componentDatatype,
                componentsPerAttribute: attribute.componentsPerAttribute,
                normalize: attribute.normalize,
                offsetInBytes: offsetsInBytes[name],
                strideInBytes: strideInBytes,
              });
            } else {
              // Constant attribute for all vertices
              vaAttributes.push({
                index: attributeLocations[name],
                value: attribute.value,
                componentDatatype: attribute.componentDatatype,
                normalize: attribute.normalize,
              });
            }
          }
        }
      }
    } else {
      // One vertex buffer per attribute.
      for (name in attributes) {
        if (attributes.hasOwnProperty(name) && defined(attributes[name])) {
          attribute = attributes[name];

          var componentDatatype = attribute.componentDatatype;
          if (componentDatatype === ComponentDatatype$1.DOUBLE) {
            componentDatatype = ComponentDatatype$1.FLOAT;
          }

          vertexBuffer = undefined;
          if (defined(attribute.values)) {
            vertexBuffer = Buffer$1.createVertexBuffer({
              context: context,
              typedArray: ComponentDatatype$1.createTypedArray(
                componentDatatype,
                attribute.values
              ),
              usage: bufferUsage,
            });
          }

          vaAttributes.push({
            index: attributeLocations[name],
            vertexBuffer: vertexBuffer,
            value: attribute.value,
            componentDatatype: componentDatatype,
            componentsPerAttribute: attribute.componentsPerAttribute,
            normalize: attribute.normalize,
          });
        }
      }
    }

    var indexBuffer;
    var indices = geometry.indices;
    if (defined(indices)) {
      if (
        Geometry.computeNumberOfVertices(geometry) >=
          CesiumMath.SIXTY_FOUR_KILOBYTES &&
        context.elementIndexUint
      ) {
        indexBuffer = Buffer$1.createIndexBuffer({
          context: context,
          typedArray: new Uint32Array(indices),
          usage: bufferUsage,
          indexDatatype: IndexDatatype$1.UNSIGNED_INT,
        });
      } else {
        indexBuffer = Buffer$1.createIndexBuffer({
          context: context,
          typedArray: new Uint16Array(indices),
          usage: bufferUsage,
          indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
        });
      }
    }

    return new VertexArray({
      context: context,
      attributes: vaAttributes,
      indexBuffer: indexBuffer,
    });
  };

  Object.defineProperties(VertexArray.prototype, {
    numberOfAttributes: {
      get: function () {
        return this._attributes.length;
      },
    },
    numberOfVertices: {
      get: function () {
        return this._numberOfVertices;
      },
    },
    indexBuffer: {
      get: function () {
        return this._indexBuffer;
      },
    },
  });

  /**
   * index is the location in the array of attributes, not the index property of an attribute.
   */
  VertexArray.prototype.getAttribute = function (index) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("index", index);
    //>>includeEnd('debug');

    return this._attributes[index];
  };

  // Workaround for ANGLE, where the attribute divisor seems to be part of the global state instead
  // of the VAO state. This function is called when the vao is bound, and should be removed
  // once the ANGLE issue is resolved. Setting the divisor should normally happen in vertexAttrib and
  // disableVertexAttribArray.
  function setVertexAttribDivisor(vertexArray) {
    var context = vertexArray._context;
    var hasInstancedAttributes = vertexArray._hasInstancedAttributes;
    if (!hasInstancedAttributes && !context._previousDrawInstanced) {
      return;
    }
    context._previousDrawInstanced = hasInstancedAttributes;

    var divisors = context._vertexAttribDivisors;
    var attributes = vertexArray._attributes;
    var maxAttributes = ContextLimits.maximumVertexAttributes;
    var i;

    if (hasInstancedAttributes) {
      var length = attributes.length;
      for (i = 0; i < length; ++i) {
        var attribute = attributes[i];
        if (attribute.enabled) {
          var divisor = attribute.instanceDivisor;
          var index = attribute.index;
          if (divisor !== divisors[index]) {
            context.glVertexAttribDivisor(index, divisor);
            divisors[index] = divisor;
          }
        }
      }
    } else {
      for (i = 0; i < maxAttributes; ++i) {
        if (divisors[i] > 0) {
          context.glVertexAttribDivisor(i, 0);
          divisors[i] = 0;
        }
      }
    }
  }

  // Vertex attributes backed by a constant value go through vertexAttrib[1234]f[v]
  // which is part of context state rather than VAO state.
  function setConstantAttributes(vertexArray, gl) {
    var attributes = vertexArray._attributes;
    var length = attributes.length;
    for (var i = 0; i < length; ++i) {
      var attribute = attributes[i];
      if (attribute.enabled && defined(attribute.value)) {
        attribute.vertexAttrib(gl);
      }
    }
  }

  VertexArray.prototype._bind = function () {
    if (defined(this._vao)) {
      this._context.glBindVertexArray(this._vao);
      if (this._context.instancedArrays) {
        setVertexAttribDivisor(this);
      }
      if (this._hasConstantAttributes) {
        setConstantAttributes(this, this._gl);
      }
    } else {
      bind(this._gl, this._attributes, this._indexBuffer);
    }
  };

  VertexArray.prototype._unBind = function () {
    if (defined(this._vao)) {
      this._context.glBindVertexArray(null);
    } else {
      var attributes = this._attributes;
      var gl = this._gl;

      for (var i = 0; i < attributes.length; ++i) {
        var attribute = attributes[i];
        if (attribute.enabled) {
          attribute.disableVertexAttribArray(gl);
        }
      }
      if (this._indexBuffer) {
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, null);
      }
    }
  };

  VertexArray.prototype.isDestroyed = function () {
    return false;
  };

  VertexArray.prototype.destroy = function () {
    var attributes = this._attributes;
    for (var i = 0; i < attributes.length; ++i) {
      var vertexBuffer = attributes[i].vertexBuffer;
      if (
        defined(vertexBuffer) &&
        !vertexBuffer.isDestroyed() &&
        vertexBuffer.vertexArrayDestroyable
      ) {
        vertexBuffer.destroy();
      }
    }

    var indexBuffer = this._indexBuffer;
    if (
      defined(indexBuffer) &&
      !indexBuffer.isDestroyed() &&
      indexBuffer.vertexArrayDestroyable
    ) {
      indexBuffer.destroy();
    }

    if (defined(this._vao)) {
      this._context.glDeleteVertexArray(this._vao);
    }

    return destroyObject(this);
  };

  /**
   * Creates a texture to look up per instance attributes for batched primitives. For example, store each primitive's pick color in the texture.
   *
   * @alias BatchTable
   * @constructor
   * @private
   *
   * @param {Context} context The context in which the batch table is created.
   * @param {Object[]} attributes An array of objects describing a per instance attribute. Each object contains a datatype, components per attributes, whether it is normalized and a function name
   *     to retrieve the value in the vertex shader.
   * @param {Number} numberOfInstances The number of instances in a batch table.
   *
   * @example
   * // create the batch table
   * var attributes = [{
   *     functionName : 'getShow',
   *     componentDatatype : ComponentDatatype.UNSIGNED_BYTE,
   *     componentsPerAttribute : 1
   * }, {
   *     functionName : 'getPickColor',
   *     componentDatatype : ComponentDatatype.UNSIGNED_BYTE,
   *     componentsPerAttribute : 4,
   *     normalize : true
   * }];
   * var batchTable = new BatchTable(context, attributes, 5);
   *
   * // when creating the draw commands, update the uniform map and the vertex shader
   * vertexShaderSource = batchTable.getVertexShaderCallback()(vertexShaderSource);
   * var shaderProgram = ShaderProgram.fromCache({
   *    // ...
   *    vertexShaderSource : vertexShaderSource,
   * });
   *
   * drawCommand.shaderProgram = shaderProgram;
   * drawCommand.uniformMap = batchTable.getUniformMapCallback()(uniformMap);
   *
   * // use the attribute function names in the shader to retrieve the instance values
   * // ...
   * attribute float batchId;
   *
   * void main() {
   *     // ...
   *     float show = getShow(batchId);
   *     vec3 pickColor = getPickColor(batchId);
   *     // ...
   * }
   */
  function BatchTable(context, attributes, numberOfInstances) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(context)) {
      throw new DeveloperError("context is required");
    }
    if (!defined(attributes)) {
      throw new DeveloperError("attributes is required");
    }
    if (!defined(numberOfInstances)) {
      throw new DeveloperError("numberOfInstances is required");
    }
    //>>includeEnd('debug');

    this._attributes = attributes;
    this._numberOfInstances = numberOfInstances;

    if (attributes.length === 0) {
      return;
    }

    // PERFORMANCE_IDEA: We may be able to arrange the attributes so they can be packing into fewer texels.
    // Right now, an attribute with one component uses an entire texel when 4 single component attributes can
    // be packed into a texel.
    //
    // Packing floats into unsigned byte textures makes the problem worse. A single component float attribute
    // will be packed into a single texel leaving 3 texels unused. 4 texels are reserved for each float attribute
    // regardless of how many components it has.
    var pixelDatatype = getDatatype(attributes);
    var textureFloatSupported = context.floatingPointTexture;
    var packFloats =
      pixelDatatype === PixelDatatype$1.FLOAT && !textureFloatSupported;
    var offsets = createOffsets(attributes, packFloats);

    var stride = getStride(offsets, attributes, packFloats);
    var maxNumberOfInstancesPerRow = Math.floor(
      ContextLimits.maximumTextureSize / stride
    );

    var instancesPerWidth = Math.min(
      numberOfInstances,
      maxNumberOfInstancesPerRow
    );
    var width = stride * instancesPerWidth;
    var height = Math.ceil(numberOfInstances / instancesPerWidth);

    var stepX = 1.0 / width;
    var centerX = stepX * 0.5;
    var stepY = 1.0 / height;
    var centerY = stepY * 0.5;

    this._textureDimensions = new Cartesian2(width, height);
    this._textureStep = new Cartesian4(stepX, centerX, stepY, centerY);
    this._pixelDatatype = !packFloats
      ? pixelDatatype
      : PixelDatatype$1.UNSIGNED_BYTE;
    this._packFloats = packFloats;
    this._offsets = offsets;
    this._stride = stride;
    this._texture = undefined;

    var batchLength = 4 * width * height;
    this._batchValues =
      pixelDatatype === PixelDatatype$1.FLOAT && !packFloats
        ? new Float32Array(batchLength)
        : new Uint8Array(batchLength);
    this._batchValuesDirty = false;
  }

  Object.defineProperties(BatchTable.prototype, {
    /**
     * The attribute descriptions.
     * @memberOf BatchTable.prototype
     * @type {Object[]}
     * @readonly
     */
    attributes: {
      get: function () {
        return this._attributes;
      },
    },
    /**
     * The number of instances.
     * @memberOf BatchTable.prototype
     * @type {Number}
     * @readonly
     */
    numberOfInstances: {
      get: function () {
        return this._numberOfInstances;
      },
    },
  });

  function getDatatype(attributes) {
    var foundFloatDatatype = false;
    var length = attributes.length;
    for (var i = 0; i < length; ++i) {
      if (attributes[i].componentDatatype !== ComponentDatatype$1.UNSIGNED_BYTE) {
        foundFloatDatatype = true;
        break;
      }
    }
    return foundFloatDatatype ? PixelDatatype$1.FLOAT : PixelDatatype$1.UNSIGNED_BYTE;
  }

  function getAttributeType(attributes, attributeIndex) {
    var componentsPerAttribute =
      attributes[attributeIndex].componentsPerAttribute;
    if (componentsPerAttribute === 2) {
      return Cartesian2;
    } else if (componentsPerAttribute === 3) {
      return Cartesian3;
    } else if (componentsPerAttribute === 4) {
      return Cartesian4;
    }
    return Number;
  }

  function createOffsets(attributes, packFloats) {
    var offsets = new Array(attributes.length);

    var currentOffset = 0;
    var attributesLength = attributes.length;
    for (var i = 0; i < attributesLength; ++i) {
      var attribute = attributes[i];
      var componentDatatype = attribute.componentDatatype;

      offsets[i] = currentOffset;

      if (componentDatatype !== ComponentDatatype$1.UNSIGNED_BYTE && packFloats) {
        currentOffset += 4;
      } else {
        ++currentOffset;
      }
    }

    return offsets;
  }

  function getStride(offsets, attributes, packFloats) {
    var length = offsets.length;
    var lastOffset = offsets[length - 1];
    var lastAttribute = attributes[length - 1];
    var componentDatatype = lastAttribute.componentDatatype;

    if (componentDatatype !== ComponentDatatype$1.UNSIGNED_BYTE && packFloats) {
      return lastOffset + 4;
    }
    return lastOffset + 1;
  }

  var scratchPackedFloatCartesian4 = new Cartesian4();

  function getPackedFloat(array, index, result) {
    var packed = Cartesian4.unpack(array, index, scratchPackedFloatCartesian4);
    var x = Cartesian4.unpackFloat(packed);

    packed = Cartesian4.unpack(array, index + 4, scratchPackedFloatCartesian4);
    var y = Cartesian4.unpackFloat(packed);

    packed = Cartesian4.unpack(array, index + 8, scratchPackedFloatCartesian4);
    var z = Cartesian4.unpackFloat(packed);

    packed = Cartesian4.unpack(array, index + 12, scratchPackedFloatCartesian4);
    var w = Cartesian4.unpackFloat(packed);

    return Cartesian4.fromElements(x, y, z, w, result);
  }

  function setPackedAttribute(value, array, index) {
    var packed = Cartesian4.packFloat(value.x, scratchPackedFloatCartesian4);
    Cartesian4.pack(packed, array, index);

    packed = Cartesian4.packFloat(value.y, packed);
    Cartesian4.pack(packed, array, index + 4);

    packed = Cartesian4.packFloat(value.z, packed);
    Cartesian4.pack(packed, array, index + 8);

    packed = Cartesian4.packFloat(value.w, packed);
    Cartesian4.pack(packed, array, index + 12);
  }

  var scratchGetAttributeCartesian4 = new Cartesian4();

  /**
   * Gets the value of an attribute in the table.
   *
   * @param {Number} instanceIndex The index of the instance.
   * @param {Number} attributeIndex The index of the attribute.
   * @param {undefined|Cartesian2|Cartesian3|Cartesian4} [result] The object onto which to store the result. The type is dependent on the attribute's number of components.
   * @returns {Number|Cartesian2|Cartesian3|Cartesian4} The attribute value stored for the instance.
   *
   * @exception {DeveloperError} instanceIndex is out of range.
   * @exception {DeveloperError} attributeIndex is out of range.
   */
  BatchTable.prototype.getBatchedAttribute = function (
    instanceIndex,
    attributeIndex,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (instanceIndex < 0 || instanceIndex >= this._numberOfInstances) {
      throw new DeveloperError("instanceIndex is out of range.");
    }
    if (attributeIndex < 0 || attributeIndex >= this._attributes.length) {
      throw new DeveloperError("attributeIndex is out of range");
    }
    //>>includeEnd('debug');

    var attributes = this._attributes;
    var offset = this._offsets[attributeIndex];
    var stride = this._stride;

    var index = 4 * stride * instanceIndex + 4 * offset;
    var value;

    if (
      this._packFloats &&
      attributes[attributeIndex].componentDatatype !== PixelDatatype$1.UNSIGNED_BYTE
    ) {
      value = getPackedFloat(
        this._batchValues,
        index,
        scratchGetAttributeCartesian4
      );
    } else {
      value = Cartesian4.unpack(
        this._batchValues,
        index,
        scratchGetAttributeCartesian4
      );
    }

    var attributeType = getAttributeType(attributes, attributeIndex);
    if (defined(attributeType.fromCartesian4)) {
      return attributeType.fromCartesian4(value, result);
    } else if (defined(attributeType.clone)) {
      return attributeType.clone(value, result);
    }

    return value.x;
  };

  var setAttributeScratchValues = [
    undefined,
    undefined,
    new Cartesian2(),
    new Cartesian3(),
    new Cartesian4(),
  ];
  var setAttributeScratchCartesian4 = new Cartesian4();

  /**
   * Sets the value of an attribute in the table.
   *
   * @param {Number} instanceIndex The index of the instance.
   * @param {Number} attributeIndex The index of the attribute.
   * @param {Number|Cartesian2|Cartesian3|Cartesian4} value The value to be stored in the table. The type of value will depend on the number of components of the attribute.
   *
   * @exception {DeveloperError} instanceIndex is out of range.
   * @exception {DeveloperError} attributeIndex is out of range.
   */
  BatchTable.prototype.setBatchedAttribute = function (
    instanceIndex,
    attributeIndex,
    value
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (instanceIndex < 0 || instanceIndex >= this._numberOfInstances) {
      throw new DeveloperError("instanceIndex is out of range.");
    }
    if (attributeIndex < 0 || attributeIndex >= this._attributes.length) {
      throw new DeveloperError("attributeIndex is out of range");
    }
    if (!defined(value)) {
      throw new DeveloperError("value is required.");
    }
    //>>includeEnd('debug');

    var attributes = this._attributes;
    var result =
      setAttributeScratchValues[
        attributes[attributeIndex].componentsPerAttribute
      ];
    var currentAttribute = this.getBatchedAttribute(
      instanceIndex,
      attributeIndex,
      result
    );
    var attributeType = getAttributeType(this._attributes, attributeIndex);
    var entriesEqual = defined(attributeType.equals)
      ? attributeType.equals(currentAttribute, value)
      : currentAttribute === value;
    if (entriesEqual) {
      return;
    }

    var attributeValue = setAttributeScratchCartesian4;
    attributeValue.x = defined(value.x) ? value.x : value;
    attributeValue.y = defined(value.y) ? value.y : 0.0;
    attributeValue.z = defined(value.z) ? value.z : 0.0;
    attributeValue.w = defined(value.w) ? value.w : 0.0;

    var offset = this._offsets[attributeIndex];
    var stride = this._stride;
    var index = 4 * stride * instanceIndex + 4 * offset;

    if (
      this._packFloats &&
      attributes[attributeIndex].componentDatatype !== PixelDatatype$1.UNSIGNED_BYTE
    ) {
      setPackedAttribute(attributeValue, this._batchValues, index);
    } else {
      Cartesian4.pack(attributeValue, this._batchValues, index);
    }

    this._batchValuesDirty = true;
  };

  function createTexture(batchTable, context) {
    var dimensions = batchTable._textureDimensions;
    batchTable._texture = new Texture({
      context: context,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: batchTable._pixelDatatype,
      width: dimensions.x,
      height: dimensions.y,
      sampler: Sampler.NEAREST,
      flipY: false,
    });
  }

  function updateTexture(batchTable) {
    var dimensions = batchTable._textureDimensions;
    batchTable._texture.copyFrom({
      width: dimensions.x,
      height: dimensions.y,
      arrayBufferView: batchTable._batchValues,
    });
  }

  /**
   * Creates/updates the batch table texture.
   * @param {FrameState} frameState The frame state.
   *
   * @exception {RuntimeError} The floating point texture extension is required but not supported.
   */
  BatchTable.prototype.update = function (frameState) {
    if (
      (defined(this._texture) && !this._batchValuesDirty) ||
      this._attributes.length === 0
    ) {
      return;
    }

    this._batchValuesDirty = false;

    if (!defined(this._texture)) {
      createTexture(this, frameState.context);
    }
    updateTexture(this);
  };

  /**
   * Gets a function that will update a uniform map to contain values for looking up values in the batch table.
   *
   * @returns {BatchTable.updateUniformMapCallback} A callback for updating uniform maps.
   */
  BatchTable.prototype.getUniformMapCallback = function () {
    var that = this;
    return function (uniformMap) {
      if (that._attributes.length === 0) {
        return uniformMap;
      }

      var batchUniformMap = {
        batchTexture: function () {
          return that._texture;
        },
        batchTextureDimensions: function () {
          return that._textureDimensions;
        },
        batchTextureStep: function () {
          return that._textureStep;
        },
      };
      return combine(uniformMap, batchUniformMap);
    };
  };

  function getGlslComputeSt(batchTable) {
    var stride = batchTable._stride;

    // GLSL batchId is zero-based: [0, numberOfInstances - 1]
    if (batchTable._textureDimensions.y === 1) {
      return (
        "uniform vec4 batchTextureStep; \n" +
        "vec2 computeSt(float batchId) \n" +
        "{ \n" +
        "    float stepX = batchTextureStep.x; \n" +
        "    float centerX = batchTextureStep.y; \n" +
        "    float numberOfAttributes = float(" +
        stride +
        "); \n" +
        "    return vec2(centerX + (batchId * numberOfAttributes * stepX), 0.5); \n" +
        "} \n"
      );
    }

    return (
      "uniform vec4 batchTextureStep; \n" +
      "uniform vec2 batchTextureDimensions; \n" +
      "vec2 computeSt(float batchId) \n" +
      "{ \n" +
      "    float stepX = batchTextureStep.x; \n" +
      "    float centerX = batchTextureStep.y; \n" +
      "    float stepY = batchTextureStep.z; \n" +
      "    float centerY = batchTextureStep.w; \n" +
      "    float numberOfAttributes = float(" +
      stride +
      "); \n" +
      "    float xId = mod(batchId * numberOfAttributes, batchTextureDimensions.x); \n" +
      "    float yId = floor(batchId * numberOfAttributes / batchTextureDimensions.x); \n" +
      "    return vec2(centerX + (xId * stepX), centerY + (yId * stepY)); \n" +
      "} \n"
    );
  }

  function getComponentType(componentsPerAttribute) {
    if (componentsPerAttribute === 1) {
      return "float";
    }
    return "vec" + componentsPerAttribute;
  }

  function getComponentSwizzle(componentsPerAttribute) {
    if (componentsPerAttribute === 1) {
      return ".x";
    } else if (componentsPerAttribute === 2) {
      return ".xy";
    } else if (componentsPerAttribute === 3) {
      return ".xyz";
    }
    return "";
  }

  function getGlslAttributeFunction(batchTable, attributeIndex) {
    var attributes = batchTable._attributes;
    var attribute = attributes[attributeIndex];
    var componentsPerAttribute = attribute.componentsPerAttribute;
    var functionName = attribute.functionName;
    var functionReturnType = getComponentType(componentsPerAttribute);
    var functionReturnValue = getComponentSwizzle(componentsPerAttribute);

    var offset = batchTable._offsets[attributeIndex];

    var glslFunction =
      functionReturnType +
      " " +
      functionName +
      "(float batchId) \n" +
      "{ \n" +
      "    vec2 st = computeSt(batchId); \n" +
      "    st.x += batchTextureStep.x * float(" +
      offset +
      "); \n";

    if (
      batchTable._packFloats &&
      attribute.componentDatatype !== PixelDatatype$1.UNSIGNED_BYTE
    ) {
      glslFunction +=
        "vec4 textureValue; \n" +
        "textureValue.x = czm_unpackFloat(texture2D(batchTexture, st)); \n" +
        "textureValue.y = czm_unpackFloat(texture2D(batchTexture, st + vec2(batchTextureStep.x, 0.0))); \n" +
        "textureValue.z = czm_unpackFloat(texture2D(batchTexture, st + vec2(batchTextureStep.x * 2.0, 0.0))); \n" +
        "textureValue.w = czm_unpackFloat(texture2D(batchTexture, st + vec2(batchTextureStep.x * 3.0, 0.0))); \n";
    } else {
      glslFunction += "    vec4 textureValue = texture2D(batchTexture, st); \n";
    }

    glslFunction +=
      "    " +
      functionReturnType +
      " value = textureValue" +
      functionReturnValue +
      "; \n";

    if (
      batchTable._pixelDatatype === PixelDatatype$1.UNSIGNED_BYTE &&
      attribute.componentDatatype === ComponentDatatype$1.UNSIGNED_BYTE &&
      !attribute.normalize
    ) {
      glslFunction += "value *= 255.0; \n";
    } else if (
      batchTable._pixelDatatype === PixelDatatype$1.FLOAT &&
      attribute.componentDatatype === ComponentDatatype$1.UNSIGNED_BYTE &&
      attribute.normalize
    ) {
      glslFunction += "value /= 255.0; \n";
    }

    glslFunction += "    return value; \n" + "} \n";
    return glslFunction;
  }

  /**
   * Gets a function that will update a vertex shader to contain functions for looking up values in the batch table.
   *
   * @returns {BatchTable.updateVertexShaderSourceCallback} A callback for updating a vertex shader source.
   */
  BatchTable.prototype.getVertexShaderCallback = function () {
    var attributes = this._attributes;
    if (attributes.length === 0) {
      return function (source) {
        return source;
      };
    }

    var batchTableShader = "uniform highp sampler2D batchTexture; \n";
    batchTableShader += getGlslComputeSt(this) + "\n";

    var length = attributes.length;
    for (var i = 0; i < length; ++i) {
      batchTableShader += getGlslAttributeFunction(this, i);
    }

    return function (source) {
      var mainIndex = source.indexOf("void main");
      var beforeMain = source.substring(0, mainIndex);
      var afterMain = source.substring(mainIndex);
      return beforeMain + "\n" + batchTableShader + "\n" + afterMain;
    };
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see BatchTable#destroy
   */
  BatchTable.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see BatchTable#isDestroyed
   */
  BatchTable.prototype.destroy = function () {
    this._texture = this._texture && this._texture.destroy();
    return destroyObject(this);
  };

  function transformToWorldCoordinates(
    instances,
    primitiveModelMatrix,
    scene3DOnly
  ) {
    var toWorld = !scene3DOnly;
    var length = instances.length;
    var i;

    if (!toWorld && length > 1) {
      var modelMatrix = instances[0].modelMatrix;

      for (i = 1; i < length; ++i) {
        if (!Matrix4.equals(modelMatrix, instances[i].modelMatrix)) {
          toWorld = true;
          break;
        }
      }
    }

    if (toWorld) {
      for (i = 0; i < length; ++i) {
        if (defined(instances[i].geometry)) {
          GeometryPipeline.transformToWorldCoordinates(instances[i]);
        }
      }
    } else {
      // Leave geometry in local coordinate system; auto update model-matrix.
      Matrix4.multiplyTransformation(
        primitiveModelMatrix,
        instances[0].modelMatrix,
        primitiveModelMatrix
      );
    }
  }

  function addGeometryBatchId(geometry, batchId) {
    var attributes = geometry.attributes;
    var positionAttr = attributes.position;
    var numberOfComponents =
      positionAttr.values.length / positionAttr.componentsPerAttribute;

    attributes.batchId = new GeometryAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 1,
      values: new Float32Array(numberOfComponents),
    });

    var values = attributes.batchId.values;
    for (var j = 0; j < numberOfComponents; ++j) {
      values[j] = batchId;
    }
  }

  function addBatchIds(instances) {
    var length = instances.length;

    for (var i = 0; i < length; ++i) {
      var instance = instances[i];
      if (defined(instance.geometry)) {
        addGeometryBatchId(instance.geometry, i);
      } else if (
        defined(instance.westHemisphereGeometry) &&
        defined(instance.eastHemisphereGeometry)
      ) {
        addGeometryBatchId(instance.westHemisphereGeometry, i);
        addGeometryBatchId(instance.eastHemisphereGeometry, i);
      }
    }
  }

  function geometryPipeline(parameters) {
    var instances = parameters.instances;
    var projection = parameters.projection;
    var uintIndexSupport = parameters.elementIndexUintSupported;
    var scene3DOnly = parameters.scene3DOnly;
    var vertexCacheOptimize = parameters.vertexCacheOptimize;
    var compressVertices = parameters.compressVertices;
    var modelMatrix = parameters.modelMatrix;

    var i;
    var geometry;
    var primitiveType;
    var length = instances.length;

    for (i = 0; i < length; ++i) {
      if (defined(instances[i].geometry)) {
        primitiveType = instances[i].geometry.primitiveType;
        break;
      }
    }

    //>>includeStart('debug', pragmas.debug);
    for (i = 1; i < length; ++i) {
      if (
        defined(instances[i].geometry) &&
        instances[i].geometry.primitiveType !== primitiveType
      ) {
        throw new DeveloperError(
          "All instance geometries must have the same primitiveType."
        );
      }
    }
    //>>includeEnd('debug');

    // Unify to world coordinates before combining.
    transformToWorldCoordinates(instances, modelMatrix, scene3DOnly);

    // Clip to IDL
    if (!scene3DOnly) {
      for (i = 0; i < length; ++i) {
        if (defined(instances[i].geometry)) {
          GeometryPipeline.splitLongitude(instances[i]);
        }
      }
    }

    addBatchIds(instances);

    // Optimize for vertex shader caches
    if (vertexCacheOptimize) {
      for (i = 0; i < length; ++i) {
        var instance = instances[i];
        if (defined(instance.geometry)) {
          GeometryPipeline.reorderForPostVertexCache(instance.geometry);
          GeometryPipeline.reorderForPreVertexCache(instance.geometry);
        } else if (
          defined(instance.westHemisphereGeometry) &&
          defined(instance.eastHemisphereGeometry)
        ) {
          GeometryPipeline.reorderForPostVertexCache(
            instance.westHemisphereGeometry
          );
          GeometryPipeline.reorderForPreVertexCache(
            instance.westHemisphereGeometry
          );

          GeometryPipeline.reorderForPostVertexCache(
            instance.eastHemisphereGeometry
          );
          GeometryPipeline.reorderForPreVertexCache(
            instance.eastHemisphereGeometry
          );
        }
      }
    }

    // Combine into single geometry for better rendering performance.
    var geometries = GeometryPipeline.combineInstances(instances);

    length = geometries.length;
    for (i = 0; i < length; ++i) {
      geometry = geometries[i];

      // Split positions for GPU RTE
      var attributes = geometry.attributes;
      var name;
      if (!scene3DOnly) {
        for (name in attributes) {
          if (
            attributes.hasOwnProperty(name) &&
            attributes[name].componentDatatype === ComponentDatatype$1.DOUBLE
          ) {
            var name3D = name + "3D";
            var name2D = name + "2D";

            // Compute 2D positions
            GeometryPipeline.projectTo2D(
              geometry,
              name,
              name3D,
              name2D,
              projection
            );
            if (defined(geometry.boundingSphere) && name === "position") {
              geometry.boundingSphereCV = BoundingSphere.fromVertices(
                geometry.attributes.position2D.values
              );
            }

            GeometryPipeline.encodeAttribute(
              geometry,
              name3D,
              name3D + "High",
              name3D + "Low"
            );
            GeometryPipeline.encodeAttribute(
              geometry,
              name2D,
              name2D + "High",
              name2D + "Low"
            );
          }
        }
      } else {
        for (name in attributes) {
          if (
            attributes.hasOwnProperty(name) &&
            attributes[name].componentDatatype === ComponentDatatype$1.DOUBLE
          ) {
            GeometryPipeline.encodeAttribute(
              geometry,
              name,
              name + "3DHigh",
              name + "3DLow"
            );
          }
        }
      }

      // oct encode and pack normals, compress texture coordinates
      if (compressVertices) {
        GeometryPipeline.compressVertices(geometry);
      }
    }

    if (!uintIndexSupport) {
      // Break into multiple geometries to fit within unsigned short indices if needed
      var splitGeometries = [];
      length = geometries.length;
      for (i = 0; i < length; ++i) {
        geometry = geometries[i];
        splitGeometries = splitGeometries.concat(
          GeometryPipeline.fitToUnsignedShortIndices(geometry)
        );
      }

      geometries = splitGeometries;
    }

    return geometries;
  }

  function createPickOffsets(instances, geometryName, geometries, pickOffsets) {
    var offset;
    var indexCount;
    var geometryIndex;

    var offsetIndex = pickOffsets.length - 1;
    if (offsetIndex >= 0) {
      var pickOffset = pickOffsets[offsetIndex];
      offset = pickOffset.offset + pickOffset.count;
      geometryIndex = pickOffset.index;
      indexCount = geometries[geometryIndex].indices.length;
    } else {
      offset = 0;
      geometryIndex = 0;
      indexCount = geometries[geometryIndex].indices.length;
    }

    var length = instances.length;
    for (var i = 0; i < length; ++i) {
      var instance = instances[i];
      var geometry = instance[geometryName];
      if (!defined(geometry)) {
        continue;
      }

      var count = geometry.indices.length;

      if (offset + count > indexCount) {
        offset = 0;
        indexCount = geometries[++geometryIndex].indices.length;
      }

      pickOffsets.push({
        index: geometryIndex,
        offset: offset,
        count: count,
      });
      offset += count;
    }
  }

  function createInstancePickOffsets(instances, geometries) {
    var pickOffsets = [];
    createPickOffsets(instances, "geometry", geometries, pickOffsets);
    createPickOffsets(
      instances,
      "westHemisphereGeometry",
      geometries,
      pickOffsets
    );
    createPickOffsets(
      instances,
      "eastHemisphereGeometry",
      geometries,
      pickOffsets
    );
    return pickOffsets;
  }

  /**
   * @private
   */
  var PrimitivePipeline = {};

  /**
   * @private
   */
  PrimitivePipeline.combineGeometry = function (parameters) {
    var geometries;
    var attributeLocations;
    var instances = parameters.instances;
    var length = instances.length;
    var pickOffsets;

    var offsetInstanceExtend;
    var hasOffset = false;
    if (length > 0) {
      geometries = geometryPipeline(parameters);
      if (geometries.length > 0) {
        attributeLocations = GeometryPipeline.createAttributeLocations(
          geometries[0]
        );
        if (parameters.createPickOffsets) {
          pickOffsets = createInstancePickOffsets(instances, geometries);
        }
      }
      if (
        defined(instances[0].attributes) &&
        defined(instances[0].attributes.offset)
      ) {
        offsetInstanceExtend = new Array(length);
        hasOffset = true;
      }
    }

    var boundingSpheres = new Array(length);
    var boundingSpheresCV = new Array(length);
    for (var i = 0; i < length; ++i) {
      var instance = instances[i];
      var geometry = instance.geometry;
      if (defined(geometry)) {
        boundingSpheres[i] = geometry.boundingSphere;
        boundingSpheresCV[i] = geometry.boundingSphereCV;
        if (hasOffset) {
          offsetInstanceExtend[i] = instance.geometry.offsetAttribute;
        }
      }

      var eastHemisphereGeometry = instance.eastHemisphereGeometry;
      var westHemisphereGeometry = instance.westHemisphereGeometry;
      if (defined(eastHemisphereGeometry) && defined(westHemisphereGeometry)) {
        if (
          defined(eastHemisphereGeometry.boundingSphere) &&
          defined(westHemisphereGeometry.boundingSphere)
        ) {
          boundingSpheres[i] = BoundingSphere.union(
            eastHemisphereGeometry.boundingSphere,
            westHemisphereGeometry.boundingSphere
          );
        }
        if (
          defined(eastHemisphereGeometry.boundingSphereCV) &&
          defined(westHemisphereGeometry.boundingSphereCV)
        ) {
          boundingSpheresCV[i] = BoundingSphere.union(
            eastHemisphereGeometry.boundingSphereCV,
            westHemisphereGeometry.boundingSphereCV
          );
        }
      }
    }

    return {
      geometries: geometries,
      modelMatrix: parameters.modelMatrix,
      attributeLocations: attributeLocations,
      pickOffsets: pickOffsets,
      offsetInstanceExtend: offsetInstanceExtend,
      boundingSpheres: boundingSpheres,
      boundingSpheresCV: boundingSpheresCV,
    };
  };

  function transferGeometry(geometry, transferableObjects) {
    var attributes = geometry.attributes;
    for (var name in attributes) {
      if (attributes.hasOwnProperty(name)) {
        var attribute = attributes[name];

        if (defined(attribute) && defined(attribute.values)) {
          transferableObjects.push(attribute.values.buffer);
        }
      }
    }

    if (defined(geometry.indices)) {
      transferableObjects.push(geometry.indices.buffer);
    }
  }

  function transferGeometries(geometries, transferableObjects) {
    var length = geometries.length;
    for (var i = 0; i < length; ++i) {
      transferGeometry(geometries[i], transferableObjects);
    }
  }

  // This function was created by simplifying packCreateGeometryResults into a count-only operation.
  function countCreateGeometryResults(items) {
    var count = 1;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      var geometry = items[i];
      ++count;

      if (!defined(geometry)) {
        continue;
      }

      var attributes = geometry.attributes;

      count +=
        7 +
        2 * BoundingSphere.packedLength +
        (defined(geometry.indices) ? geometry.indices.length : 0);

      for (var property in attributes) {
        if (
          attributes.hasOwnProperty(property) &&
          defined(attributes[property])
        ) {
          var attribute = attributes[property];
          count += 5 + attribute.values.length;
        }
      }
    }

    return count;
  }

  /**
   * @private
   */
  PrimitivePipeline.packCreateGeometryResults = function (
    items,
    transferableObjects
  ) {
    var packedData = new Float64Array(countCreateGeometryResults(items));
    var stringTable = [];
    var stringHash = {};

    var length = items.length;
    var count = 0;
    packedData[count++] = length;
    for (var i = 0; i < length; i++) {
      var geometry = items[i];

      var validGeometry = defined(geometry);
      packedData[count++] = validGeometry ? 1.0 : 0.0;

      if (!validGeometry) {
        continue;
      }

      packedData[count++] = geometry.primitiveType;
      packedData[count++] = geometry.geometryType;
      packedData[count++] = defaultValue(geometry.offsetAttribute, -1);

      var validBoundingSphere = defined(geometry.boundingSphere) ? 1.0 : 0.0;
      packedData[count++] = validBoundingSphere;
      if (validBoundingSphere) {
        BoundingSphere.pack(geometry.boundingSphere, packedData, count);
      }

      count += BoundingSphere.packedLength;

      var validBoundingSphereCV = defined(geometry.boundingSphereCV) ? 1.0 : 0.0;
      packedData[count++] = validBoundingSphereCV;
      if (validBoundingSphereCV) {
        BoundingSphere.pack(geometry.boundingSphereCV, packedData, count);
      }

      count += BoundingSphere.packedLength;

      var attributes = geometry.attributes;
      var attributesToWrite = [];
      for (var property in attributes) {
        if (
          attributes.hasOwnProperty(property) &&
          defined(attributes[property])
        ) {
          attributesToWrite.push(property);
          if (!defined(stringHash[property])) {
            stringHash[property] = stringTable.length;
            stringTable.push(property);
          }
        }
      }

      packedData[count++] = attributesToWrite.length;
      for (var q = 0; q < attributesToWrite.length; q++) {
        var name = attributesToWrite[q];
        var attribute = attributes[name];
        packedData[count++] = stringHash[name];
        packedData[count++] = attribute.componentDatatype;
        packedData[count++] = attribute.componentsPerAttribute;
        packedData[count++] = attribute.normalize ? 1 : 0;
        packedData[count++] = attribute.values.length;
        packedData.set(attribute.values, count);
        count += attribute.values.length;
      }

      var indicesLength = defined(geometry.indices) ? geometry.indices.length : 0;
      packedData[count++] = indicesLength;

      if (indicesLength > 0) {
        packedData.set(geometry.indices, count);
        count += indicesLength;
      }
    }

    transferableObjects.push(packedData.buffer);

    return {
      stringTable: stringTable,
      packedData: packedData,
    };
  };

  /**
   * @private
   */
  PrimitivePipeline.unpackCreateGeometryResults = function (
    createGeometryResult
  ) {
    var stringTable = createGeometryResult.stringTable;
    var packedGeometry = createGeometryResult.packedData;

    var i;
    var result = new Array(packedGeometry[0]);
    var resultIndex = 0;

    var packedGeometryIndex = 1;
    while (packedGeometryIndex < packedGeometry.length) {
      var valid = packedGeometry[packedGeometryIndex++] === 1.0;
      if (!valid) {
        result[resultIndex++] = undefined;
        continue;
      }

      var primitiveType = packedGeometry[packedGeometryIndex++];
      var geometryType = packedGeometry[packedGeometryIndex++];
      var offsetAttribute = packedGeometry[packedGeometryIndex++];
      if (offsetAttribute === -1) {
        offsetAttribute = undefined;
      }

      var boundingSphere;
      var boundingSphereCV;

      var validBoundingSphere = packedGeometry[packedGeometryIndex++] === 1.0;
      if (validBoundingSphere) {
        boundingSphere = BoundingSphere.unpack(
          packedGeometry,
          packedGeometryIndex
        );
      }

      packedGeometryIndex += BoundingSphere.packedLength;

      var validBoundingSphereCV = packedGeometry[packedGeometryIndex++] === 1.0;
      if (validBoundingSphereCV) {
        boundingSphereCV = BoundingSphere.unpack(
          packedGeometry,
          packedGeometryIndex
        );
      }

      packedGeometryIndex += BoundingSphere.packedLength;

      var length;
      var values;
      var componentsPerAttribute;
      var attributes = new GeometryAttributes();
      var numAttributes = packedGeometry[packedGeometryIndex++];
      for (i = 0; i < numAttributes; i++) {
        var name = stringTable[packedGeometry[packedGeometryIndex++]];
        var componentDatatype = packedGeometry[packedGeometryIndex++];
        componentsPerAttribute = packedGeometry[packedGeometryIndex++];
        var normalize = packedGeometry[packedGeometryIndex++] !== 0;

        length = packedGeometry[packedGeometryIndex++];
        values = ComponentDatatype$1.createTypedArray(componentDatatype, length);
        for (var valuesIndex = 0; valuesIndex < length; valuesIndex++) {
          values[valuesIndex] = packedGeometry[packedGeometryIndex++];
        }

        attributes[name] = new GeometryAttribute({
          componentDatatype: componentDatatype,
          componentsPerAttribute: componentsPerAttribute,
          normalize: normalize,
          values: values,
        });
      }

      var indices;
      length = packedGeometry[packedGeometryIndex++];

      if (length > 0) {
        var numberOfVertices = values.length / componentsPerAttribute;
        indices = IndexDatatype$1.createTypedArray(numberOfVertices, length);
        for (i = 0; i < length; i++) {
          indices[i] = packedGeometry[packedGeometryIndex++];
        }
      }

      result[resultIndex++] = new Geometry({
        primitiveType: primitiveType,
        geometryType: geometryType,
        boundingSphere: boundingSphere,
        boundingSphereCV: boundingSphereCV,
        indices: indices,
        attributes: attributes,
        offsetAttribute: offsetAttribute,
      });
    }

    return result;
  };

  function packInstancesForCombine(instances, transferableObjects) {
    var length = instances.length;
    var packedData = new Float64Array(1 + length * 19);
    var count = 0;
    packedData[count++] = length;
    for (var i = 0; i < length; i++) {
      var instance = instances[i];
      Matrix4.pack(instance.modelMatrix, packedData, count);
      count += Matrix4.packedLength;
      if (defined(instance.attributes) && defined(instance.attributes.offset)) {
        var values = instance.attributes.offset.value;
        packedData[count] = values[0];
        packedData[count + 1] = values[1];
        packedData[count + 2] = values[2];
      }
      count += 3;
    }
    transferableObjects.push(packedData.buffer);

    return packedData;
  }

  function unpackInstancesForCombine(data) {
    var packedInstances = data;
    var result = new Array(packedInstances[0]);
    var count = 0;

    var i = 1;
    while (i < packedInstances.length) {
      var modelMatrix = Matrix4.unpack(packedInstances, i);
      var attributes;
      i += Matrix4.packedLength;
      if (defined(packedInstances[i])) {
        attributes = {
          offset: new OffsetGeometryInstanceAttribute(
            packedInstances[i],
            packedInstances[i + 1],
            packedInstances[i + 2]
          ),
        };
      }
      i += 3;

      result[count++] = {
        modelMatrix: modelMatrix,
        attributes: attributes,
      };
    }

    return result;
  }

  /**
   * @private
   */
  PrimitivePipeline.packCombineGeometryParameters = function (
    parameters,
    transferableObjects
  ) {
    var createGeometryResults = parameters.createGeometryResults;
    var length = createGeometryResults.length;

    for (var i = 0; i < length; i++) {
      transferableObjects.push(createGeometryResults[i].packedData.buffer);
    }

    return {
      createGeometryResults: parameters.createGeometryResults,
      packedInstances: packInstancesForCombine(
        parameters.instances,
        transferableObjects
      ),
      ellipsoid: parameters.ellipsoid,
      isGeographic: parameters.projection instanceof GeographicProjection,
      elementIndexUintSupported: parameters.elementIndexUintSupported,
      scene3DOnly: parameters.scene3DOnly,
      vertexCacheOptimize: parameters.vertexCacheOptimize,
      compressVertices: parameters.compressVertices,
      modelMatrix: parameters.modelMatrix,
      createPickOffsets: parameters.createPickOffsets,
    };
  };

  /**
   * @private
   */
  PrimitivePipeline.unpackCombineGeometryParameters = function (
    packedParameters
  ) {
    var instances = unpackInstancesForCombine(packedParameters.packedInstances);
    var createGeometryResults = packedParameters.createGeometryResults;
    var length = createGeometryResults.length;
    var instanceIndex = 0;

    for (var resultIndex = 0; resultIndex < length; resultIndex++) {
      var geometries = PrimitivePipeline.unpackCreateGeometryResults(
        createGeometryResults[resultIndex]
      );
      var geometriesLength = geometries.length;
      for (
        var geometryIndex = 0;
        geometryIndex < geometriesLength;
        geometryIndex++
      ) {
        var geometry = geometries[geometryIndex];
        var instance = instances[instanceIndex];
        instance.geometry = geometry;
        ++instanceIndex;
      }
    }

    var ellipsoid = Ellipsoid.clone(packedParameters.ellipsoid);
    var projection = packedParameters.isGeographic
      ? new GeographicProjection(ellipsoid)
      : new WebMercatorProjection(ellipsoid);

    return {
      instances: instances,
      ellipsoid: ellipsoid,
      projection: projection,
      elementIndexUintSupported: packedParameters.elementIndexUintSupported,
      scene3DOnly: packedParameters.scene3DOnly,
      vertexCacheOptimize: packedParameters.vertexCacheOptimize,
      compressVertices: packedParameters.compressVertices,
      modelMatrix: Matrix4.clone(packedParameters.modelMatrix),
      createPickOffsets: packedParameters.createPickOffsets,
    };
  };

  function packBoundingSpheres(boundingSpheres) {
    var length = boundingSpheres.length;
    var bufferLength = 1 + (BoundingSphere.packedLength + 1) * length;
    var buffer = new Float32Array(bufferLength);

    var bufferIndex = 0;
    buffer[bufferIndex++] = length;

    for (var i = 0; i < length; ++i) {
      var bs = boundingSpheres[i];
      if (!defined(bs)) {
        buffer[bufferIndex++] = 0.0;
      } else {
        buffer[bufferIndex++] = 1.0;
        BoundingSphere.pack(boundingSpheres[i], buffer, bufferIndex);
      }
      bufferIndex += BoundingSphere.packedLength;
    }

    return buffer;
  }

  function unpackBoundingSpheres(buffer) {
    var result = new Array(buffer[0]);
    var count = 0;

    var i = 1;
    while (i < buffer.length) {
      if (buffer[i++] === 1.0) {
        result[count] = BoundingSphere.unpack(buffer, i);
      }
      ++count;
      i += BoundingSphere.packedLength;
    }

    return result;
  }

  /**
   * @private
   */
  PrimitivePipeline.packCombineGeometryResults = function (
    results,
    transferableObjects
  ) {
    if (defined(results.geometries)) {
      transferGeometries(results.geometries, transferableObjects);
    }

    var packedBoundingSpheres = packBoundingSpheres(results.boundingSpheres);
    var packedBoundingSpheresCV = packBoundingSpheres(results.boundingSpheresCV);
    transferableObjects.push(
      packedBoundingSpheres.buffer,
      packedBoundingSpheresCV.buffer
    );

    return {
      geometries: results.geometries,
      attributeLocations: results.attributeLocations,
      modelMatrix: results.modelMatrix,
      pickOffsets: results.pickOffsets,
      offsetInstanceExtend: results.offsetInstanceExtend,
      boundingSpheres: packedBoundingSpheres,
      boundingSpheresCV: packedBoundingSpheresCV,
    };
  };

  /**
   * @private
   */
  PrimitivePipeline.unpackCombineGeometryResults = function (packedResult) {
    return {
      geometries: packedResult.geometries,
      attributeLocations: packedResult.attributeLocations,
      modelMatrix: packedResult.modelMatrix,
      pickOffsets: packedResult.pickOffsets,
      offsetInstanceExtend: packedResult.offsetInstanceExtend,
      boundingSpheres: unpackBoundingSpheres(packedResult.boundingSpheres),
      boundingSpheresCV: unpackBoundingSpheres(packedResult.boundingSpheresCV),
    };
  };

  /**
   * @private
   */
  var PrimitiveState = {
    READY: 0,
    CREATING: 1,
    CREATED: 2,
    COMBINING: 3,
    COMBINED: 4,
    COMPLETE: 5,
    FAILED: 6,
  };
  var PrimitiveState$1 = Object.freeze(PrimitiveState);

  /**
   * Indicates if the scene is viewed in 3D, 2D, or 2.5D Columbus view.
   *
   * @enum {Number}
   * @see Scene#mode
   */
  var SceneMode = {
    /**
     * Morphing between mode, e.g., 3D to 2D.
     *
     * @type {Number}
     * @constant
     */
    MORPHING: 0,

    /**
     * Columbus View mode.  A 2.5D perspective view where the map is laid out
     * flat and objects with non-zero height are drawn above it.
     *
     * @type {Number}
     * @constant
     */
    COLUMBUS_VIEW: 1,

    /**
     * 2D mode.  The map is viewed top-down with an orthographic projection.
     *
     * @type {Number}
     * @constant
     */
    SCENE2D: 2,

    /**
     * 3D mode.  A traditional 3D perspective view of the globe.
     *
     * @type {Number}
     * @constant
     */
    SCENE3D: 3,
  };

  /**
   * Returns the morph time for the given scene mode.
   *
   * @param {SceneMode} value The scene mode
   * @returns {Number} The morph time
   */
  SceneMode.getMorphTime = function (value) {
    if (value === SceneMode.SCENE3D) {
      return 1.0;
    } else if (value === SceneMode.MORPHING) {
      return undefined;
    }
    return 0.0;
  };
  var SceneMode$1 = Object.freeze(SceneMode);

  /**
   * Specifies whether the object casts or receives shadows from light sources when
   * shadows are enabled.
   *
   * @enum {Number}
   */
  var ShadowMode = {
    /**
     * The object does not cast or receive shadows.
     *
     * @type {Number}
     * @constant
     */
    DISABLED: 0,

    /**
     * The object casts and receives shadows.
     *
     * @type {Number}
     * @constant
     */
    ENABLED: 1,

    /**
     * The object casts shadows only.
     *
     * @type {Number}
     * @constant
     */
    CAST_ONLY: 2,

    /**
     * The object receives shadows only.
     *
     * @type {Number}
     * @constant
     */
    RECEIVE_ONLY: 3,
  };

  /**
   * @private
   */
  ShadowMode.NUMBER_OF_SHADOW_MODES = 4;

  /**
   * @private
   */
  ShadowMode.castShadows = function (shadowMode) {
    return (
      shadowMode === ShadowMode.ENABLED || shadowMode === ShadowMode.CAST_ONLY
    );
  };

  /**
   * @private
   */
  ShadowMode.receiveShadows = function (shadowMode) {
    return (
      shadowMode === ShadowMode.ENABLED || shadowMode === ShadowMode.RECEIVE_ONLY
    );
  };

  /**
   * @private
   */
  ShadowMode.fromCastReceive = function (castShadows, receiveShadows) {
    if (castShadows && receiveShadows) {
      return ShadowMode.ENABLED;
    } else if (castShadows) {
      return ShadowMode.CAST_ONLY;
    } else if (receiveShadows) {
      return ShadowMode.RECEIVE_ONLY;
    }
    return ShadowMode.DISABLED;
  };

  var ShadowMode$1 = Object.freeze(ShadowMode);

  /**
   * A primitive represents geometry in the {@link Scene}.  The geometry can be from a single {@link GeometryInstance}
   * as shown in example 1 below, or from an array of instances, even if the geometry is from different
   * geometry types, e.g., an {@link RectangleGeometry} and an {@link EllipsoidGeometry} as shown in Code Example 2.
   * <p>
   * A primitive combines geometry instances with an {@link Appearance} that describes the full shading, including
   * {@link Material} and {@link RenderState}.  Roughly, the geometry instance defines the structure and placement,
   * and the appearance defines the visual characteristics.  Decoupling geometry and appearance allows us to mix
   * and match most of them and add a new geometry or appearance independently of each other.
   * </p>
   * <p>
   * Combining multiple instances into one primitive is called batching, and significantly improves performance for static data.
   * Instances can be individually picked; {@link Scene#pick} returns their {@link GeometryInstance#id}.  Using
   * per-instance appearances like {@link PerInstanceColorAppearance}, each instance can also have a unique color.
   * </p>
   * <p>
   * {@link Geometry} can either be created and batched on a web worker or the main thread. The first two examples
   * show geometry that will be created on a web worker by using the descriptions of the geometry. The third example
   * shows how to create the geometry on the main thread by explicitly calling the <code>createGeometry</code> method.
   * </p>
   *
   * @alias Primitive
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {GeometryInstance[]|GeometryInstance} [options.geometryInstances] The geometry instances - or a single geometry instance - to render.
   * @param {Appearance} [options.appearance] The appearance used to render the primitive.
   * @param {Appearance} [options.depthFailAppearance] The appearance used to shade this primitive when it fails the depth test.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the primitive (all geometry instances) from model to world coordinates.
   * @param {Boolean} [options.vertexCacheOptimize=false] When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
   * @param {Boolean} [options.interleave=false] When <code>true</code>, geometry vertex attributes are interleaved, which can slightly improve rendering performance but increases load time.
   * @param {Boolean} [options.compressVertices=true] When <code>true</code>, the geometry vertices are compressed, which will save memory.
   * @param {Boolean} [options.releaseGeometryInstances=true] When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
   * @param {Boolean} [options.cull=true] When <code>true</code>, the renderer frustum culls and horizon culls the primitive's commands based on their bounding volume.  Set this to <code>false</code> for a small performance gain if you are manually culling the primitive.
   * @param {Boolean} [options.asynchronous=true] Determines if the primitive will be created asynchronously or block until ready.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {ShadowMode} [options.shadows=ShadowMode.DISABLED] Determines whether this primitive casts or receives shadows from light sources.
   *
   * @example
   * // 1. Draw a translucent ellipse on the surface with a checkerboard pattern
   * var instance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.EllipseGeometry({
   *       center : Cesium.Cartesian3.fromDegrees(-100.0, 20.0),
   *       semiMinorAxis : 500000.0,
   *       semiMajorAxis : 1000000.0,
   *       rotation : Cesium.Math.PI_OVER_FOUR,
   *       vertexFormat : Cesium.VertexFormat.POSITION_AND_ST
   *   }),
   *   id : 'object returned when this instance is picked and to get/set per-instance attributes'
   * });
   * scene.primitives.add(new Cesium.Primitive({
   *   geometryInstances : instance,
   *   appearance : new Cesium.EllipsoidSurfaceAppearance({
   *     material : Cesium.Material.fromType('Checkerboard')
   *   })
   * }));
   *
   * @example
   * // 2. Draw different instances each with a unique color
   * var rectangleInstance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.RectangleGeometry({
   *     rectangle : Cesium.Rectangle.fromDegrees(-140.0, 30.0, -100.0, 40.0),
   *     vertexFormat : Cesium.PerInstanceColorAppearance.VERTEX_FORMAT
   *   }),
   *   id : 'rectangle',
   *   attributes : {
   *     color : new Cesium.ColorGeometryInstanceAttribute(0.0, 1.0, 1.0, 0.5)
   *   }
   * });
   * var ellipsoidInstance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.EllipsoidGeometry({
   *     radii : new Cesium.Cartesian3(500000.0, 500000.0, 1000000.0),
   *     vertexFormat : Cesium.VertexFormat.POSITION_AND_NORMAL
   *   }),
   *   modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *     Cesium.Cartesian3.fromDegrees(-95.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 500000.0), new Cesium.Matrix4()),
   *   id : 'ellipsoid',
   *   attributes : {
   *     color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.AQUA)
   *   }
   * });
   * scene.primitives.add(new Cesium.Primitive({
   *   geometryInstances : [rectangleInstance, ellipsoidInstance],
   *   appearance : new Cesium.PerInstanceColorAppearance()
   * }));
   *
   * @example
   * // 3. Create the geometry on the main thread.
   * scene.primitives.add(new Cesium.Primitive({
   *   geometryInstances : new Cesium.GeometryInstance({
   *       geometry : Cesium.EllipsoidGeometry.createGeometry(new Cesium.EllipsoidGeometry({
   *         radii : new Cesium.Cartesian3(500000.0, 500000.0, 1000000.0),
   *         vertexFormat : Cesium.VertexFormat.POSITION_AND_NORMAL
   *       })),
   *       modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
   *         Cesium.Cartesian3.fromDegrees(-95.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 500000.0), new Cesium.Matrix4()),
   *       id : 'ellipsoid',
   *       attributes : {
   *         color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.AQUA)
   *       }
   *   }),
   *   appearance : new Cesium.PerInstanceColorAppearance()
   * }));
   *
   * @see GeometryInstance
   * @see Appearance
   * @see ClassificationPrimitive
   * @see GroundPrimitive
   */
  function Primitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The geometry instances rendered with this primitive.  This may
     * be <code>undefined</code> if <code>options.releaseGeometryInstances</code>
     * is <code>true</code> when the primitive is constructed.
     * <p>
     * Changing this property after the primitive is rendered has no effect.
     * </p>
     *
     * @readonly
     * @type GeometryInstance[]|GeometryInstance
     *
     * @default undefined
     */
    this.geometryInstances = options.geometryInstances;

    /**
     * The {@link Appearance} used to shade this primitive. Each geometry
     * instance is shaded with the same appearance.  Some appearances, like
     * {@link PerInstanceColorAppearance} allow giving each instance unique
     * properties.
     *
     * @type Appearance
     *
     * @default undefined
     */
    this.appearance = options.appearance;
    this._appearance = undefined;
    this._material = undefined;

    /**
     * The {@link Appearance} used to shade this primitive when it fails the depth test. Each geometry
     * instance is shaded with the same appearance.  Some appearances, like
     * {@link PerInstanceColorAppearance} allow giving each instance unique
     * properties.
     *
     * <p>
     * When using an appearance that requires a color attribute, like PerInstanceColorAppearance,
     * add a depthFailColor per-instance attribute instead.
     * </p>
     *
     * <p>
     * Requires the EXT_frag_depth WebGL extension to render properly. If the extension is not supported,
     * there may be artifacts.
     * </p>
     * @type Appearance
     *
     * @default undefined
     */
    this.depthFailAppearance = options.depthFailAppearance;
    this._depthFailAppearance = undefined;
    this._depthFailMaterial = undefined;

    /**
     * The 4x4 transformation matrix that transforms the primitive (all geometry instances) from model to world coordinates.
     * When this is the identity matrix, the primitive is drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * <p>
     * This property is only supported in 3D mode.
     * </p>
     *
     * @type Matrix4
     *
     * @default Matrix4.IDENTITY
     *
     * @example
     * var origin = Cesium.Cartesian3.fromDegrees(-95.0, 40.0, 200000.0);
     * p.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = new Matrix4();

    /**
     * Determines if the primitive will be shown.  This affects all geometry
     * instances in the primitive.
     *
     * @type Boolean
     *
     * @default true
     */
    this.show = defaultValue(options.show, true);

    this._vertexCacheOptimize = defaultValue(options.vertexCacheOptimize, false);
    this._interleave = defaultValue(options.interleave, false);
    this._releaseGeometryInstances = defaultValue(
      options.releaseGeometryInstances,
      true
    );
    this._allowPicking = defaultValue(options.allowPicking, true);
    this._asynchronous = defaultValue(options.asynchronous, true);
    this._compressVertices = defaultValue(options.compressVertices, true);

    /**
     * When <code>true</code>, the renderer frustum culls and horizon culls the primitive's commands
     * based on their bounding volume.  Set this to <code>false</code> for a small performance gain
     * if you are manually culling the primitive.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.cull = defaultValue(options.cull, true);

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * @private
     */
    this.rtcCenter = options.rtcCenter;

    //>>includeStart('debug', pragmas.debug);
    if (
      defined(this.rtcCenter) &&
      (!defined(this.geometryInstances) ||
        (Array.isArray(this.geometryInstances) &&
          this.geometryInstances.length !== 1))
    ) {
      throw new DeveloperError(
        "Relative-to-center rendering only supports one geometry instance."
      );
    }
    //>>includeEnd('debug');

    /**
     * Determines whether this primitive casts or receives shadows from light sources.
     *
     * @type {ShadowMode}
     *
     * @default ShadowMode.DISABLED
     */
    this.shadows = defaultValue(options.shadows, ShadowMode$1.DISABLED);

    this._translucent = undefined;

    this._state = PrimitiveState$1.READY;
    this._geometries = [];
    this._error = undefined;
    this._numberOfInstances = 0;

    this._boundingSpheres = [];
    this._boundingSphereWC = [];
    this._boundingSphereCV = [];
    this._boundingSphere2D = [];
    this._boundingSphereMorph = [];
    this._perInstanceAttributeCache = [];
    this._instanceIds = [];
    this._lastPerInstanceAttributeIndex = 0;

    this._va = [];
    this._attributeLocations = undefined;
    this._primitiveType = undefined;

    this._frontFaceRS = undefined;
    this._backFaceRS = undefined;
    this._sp = undefined;

    this._depthFailAppearance = undefined;
    this._spDepthFail = undefined;
    this._frontFaceDepthFailRS = undefined;
    this._backFaceDepthFailRS = undefined;

    this._pickIds = [];

    this._colorCommands = [];
    this._pickCommands = [];

    this._createBoundingVolumeFunction = options._createBoundingVolumeFunction;
    this._createRenderStatesFunction = options._createRenderStatesFunction;
    this._createShaderProgramFunction = options._createShaderProgramFunction;
    this._createCommandsFunction = options._createCommandsFunction;
    this._updateAndQueueCommandsFunction =
      options._updateAndQueueCommandsFunction;

    this._createPickOffsets = options._createPickOffsets;
    this._pickOffsets = undefined;

    this._createGeometryResults = undefined;
    this._ready = false;
    this._readyPromise = when.defer();

    this._batchTable = undefined;
    this._batchTableAttributeIndices = undefined;
    this._offsetInstanceExtend = undefined;
    this._batchTableOffsetAttribute2DIndex = undefined;
    this._batchTableOffsetsUpdated = false;
    this._instanceBoundingSpheres = undefined;
    this._instanceBoundingSpheresCV = undefined;
    this._tempBoundingSpheres = undefined;
    this._recomputeBoundingSpheres = false;
    this._batchTableBoundingSpheresUpdated = false;
    this._batchTableBoundingSphereAttributeIndices = undefined;
  }

  Object.defineProperties(Primitive.prototype, {
    /**
     * When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    vertexCacheOptimize: {
      get: function () {
        return this._vertexCacheOptimize;
      },
    },

    /**
     * Determines if geometry vertex attributes are interleaved, which can slightly improve rendering performance.
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    interleave: {
      get: function () {
        return this._interleave;
      },
    },

    /**
     * When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    releaseGeometryInstances: {
      get: function () {
        return this._releaseGeometryInstances;
      },
    },

    /**
     * When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.         *
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    allowPicking: {
      get: function () {
        return this._allowPicking;
      },
    },

    /**
     * Determines if the geometry instances will be created and batched on a web worker.
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    asynchronous: {
      get: function () {
        return this._asynchronous;
      },
    },

    /**
     * When <code>true</code>, geometry vertices are compressed, which will save memory.
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    compressVertices: {
      get: function () {
        return this._compressVertices;
      },
    },

    /**
     * Determines if the primitive is complete and ready to render.  If this property is
     * true, the primitive will be rendered the next time that {@link Primitive#update}
     * is called.
     *
     * @memberof Primitive.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof Primitive.prototype
     * @type {Promise.<Primitive>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  function getCommonPerInstanceAttributeNames(instances) {
    var length = instances.length;

    var attributesInAllInstances = [];
    var attributes0 = instances[0].attributes;
    var name;

    for (name in attributes0) {
      if (attributes0.hasOwnProperty(name) && defined(attributes0[name])) {
        var attribute = attributes0[name];
        var inAllInstances = true;

        // Does this same attribute exist in all instances?
        for (var i = 1; i < length; ++i) {
          var otherAttribute = instances[i].attributes[name];

          if (
            !defined(otherAttribute) ||
            attribute.componentDatatype !== otherAttribute.componentDatatype ||
            attribute.componentsPerAttribute !==
              otherAttribute.componentsPerAttribute ||
            attribute.normalize !== otherAttribute.normalize
          ) {
            inAllInstances = false;
            break;
          }
        }

        if (inAllInstances) {
          attributesInAllInstances.push(name);
        }
      }
    }

    return attributesInAllInstances;
  }

  var scratchGetAttributeCartesian2 = new Cartesian2();
  var scratchGetAttributeCartesian3 = new Cartesian3();
  var scratchGetAttributeCartesian4$1 = new Cartesian4();

  function getAttributeValue(value) {
    var componentsPerAttribute = value.length;
    if (componentsPerAttribute === 1) {
      return value[0];
    } else if (componentsPerAttribute === 2) {
      return Cartesian2.unpack(value, 0, scratchGetAttributeCartesian2);
    } else if (componentsPerAttribute === 3) {
      return Cartesian3.unpack(value, 0, scratchGetAttributeCartesian3);
    } else if (componentsPerAttribute === 4) {
      return Cartesian4.unpack(value, 0, scratchGetAttributeCartesian4$1);
    }
  }

  function createBatchTable(primitive, context) {
    var geometryInstances = primitive.geometryInstances;
    var instances = Array.isArray(geometryInstances)
      ? geometryInstances
      : [geometryInstances];
    var numberOfInstances = instances.length;
    if (numberOfInstances === 0) {
      return;
    }

    var names = getCommonPerInstanceAttributeNames(instances);
    var length = names.length;

    var attributes = [];
    var attributeIndices = {};
    var boundingSphereAttributeIndices = {};
    var offset2DIndex;

    var firstInstance = instances[0];
    var instanceAttributes = firstInstance.attributes;

    var i;
    var name;
    var attribute;

    for (i = 0; i < length; ++i) {
      name = names[i];
      attribute = instanceAttributes[name];

      attributeIndices[name] = i;
      attributes.push({
        functionName: "czm_batchTable_" + name,
        componentDatatype: attribute.componentDatatype,
        componentsPerAttribute: attribute.componentsPerAttribute,
        normalize: attribute.normalize,
      });
    }

    if (names.indexOf("distanceDisplayCondition") !== -1) {
      attributes.push(
        {
          functionName: "czm_batchTable_boundingSphereCenter3DHigh",
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          functionName: "czm_batchTable_boundingSphereCenter3DLow",
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          functionName: "czm_batchTable_boundingSphereCenter2DHigh",
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          functionName: "czm_batchTable_boundingSphereCenter2DLow",
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          functionName: "czm_batchTable_boundingSphereRadius",
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 1,
        }
      );
      boundingSphereAttributeIndices.center3DHigh = attributes.length - 5;
      boundingSphereAttributeIndices.center3DLow = attributes.length - 4;
      boundingSphereAttributeIndices.center2DHigh = attributes.length - 3;
      boundingSphereAttributeIndices.center2DLow = attributes.length - 2;
      boundingSphereAttributeIndices.radius = attributes.length - 1;
    }

    if (names.indexOf("offset") !== -1) {
      attributes.push({
        functionName: "czm_batchTable_offset2D",
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
      });
      offset2DIndex = attributes.length - 1;
    }

    attributes.push({
      functionName: "czm_batchTable_pickColor",
      componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
      componentsPerAttribute: 4,
      normalize: true,
    });

    var attributesLength = attributes.length;
    var batchTable = new BatchTable(context, attributes, numberOfInstances);

    for (i = 0; i < numberOfInstances; ++i) {
      var instance = instances[i];
      instanceAttributes = instance.attributes;

      for (var j = 0; j < length; ++j) {
        name = names[j];
        attribute = instanceAttributes[name];
        var value = getAttributeValue(attribute.value);
        var attributeIndex = attributeIndices[name];
        batchTable.setBatchedAttribute(i, attributeIndex, value);
      }

      var pickObject = {
        primitive: defaultValue(instance.pickPrimitive, primitive),
      };

      if (defined(instance.id)) {
        pickObject.id = instance.id;
      }

      var pickId = context.createPickId(pickObject);
      primitive._pickIds.push(pickId);

      var pickColor = pickId.color;
      var color = scratchGetAttributeCartesian4$1;
      color.x = Color.floatToByte(pickColor.red);
      color.y = Color.floatToByte(pickColor.green);
      color.z = Color.floatToByte(pickColor.blue);
      color.w = Color.floatToByte(pickColor.alpha);

      batchTable.setBatchedAttribute(i, attributesLength - 1, color);
    }

    primitive._batchTable = batchTable;
    primitive._batchTableAttributeIndices = attributeIndices;
    primitive._batchTableBoundingSphereAttributeIndices = boundingSphereAttributeIndices;
    primitive._batchTableOffsetAttribute2DIndex = offset2DIndex;
  }

  function cloneAttribute(attribute) {
    var clonedValues;
    if (Array.isArray(attribute.values)) {
      clonedValues = attribute.values.slice(0);
    } else {
      clonedValues = new attribute.values.constructor(attribute.values);
    }
    return new GeometryAttribute({
      componentDatatype: attribute.componentDatatype,
      componentsPerAttribute: attribute.componentsPerAttribute,
      normalize: attribute.normalize,
      values: clonedValues,
    });
  }

  function cloneGeometry(geometry) {
    var attributes = geometry.attributes;
    var newAttributes = new GeometryAttributes();
    for (var property in attributes) {
      if (attributes.hasOwnProperty(property) && defined(attributes[property])) {
        newAttributes[property] = cloneAttribute(attributes[property]);
      }
    }

    var indices;
    if (defined(geometry.indices)) {
      var sourceValues = geometry.indices;
      if (Array.isArray(sourceValues)) {
        indices = sourceValues.slice(0);
      } else {
        indices = new sourceValues.constructor(sourceValues);
      }
    }

    return new Geometry({
      attributes: newAttributes,
      indices: indices,
      primitiveType: geometry.primitiveType,
      boundingSphere: BoundingSphere.clone(geometry.boundingSphere),
    });
  }

  function cloneInstance(instance, geometry) {
    return {
      geometry: geometry,
      attributes: instance.attributes,
      modelMatrix: Matrix4.clone(instance.modelMatrix),
      pickPrimitive: instance.pickPrimitive,
      id: instance.id,
    };
  }

  var positionRegex = /attribute\s+vec(?:3|4)\s+(.*)3DHigh;/g;

  Primitive._modifyShaderPosition = function (
    primitive,
    vertexShaderSource,
    scene3DOnly
  ) {
    var match;

    var forwardDecl = "";
    var attributes = "";
    var computeFunctions = "";

    while ((match = positionRegex.exec(vertexShaderSource)) !== null) {
      var name = match[1];

      var functionName =
        "vec4 czm_compute" + name[0].toUpperCase() + name.substr(1) + "()";

      // Don't forward-declare czm_computePosition because computePosition.glsl already does.
      if (functionName !== "vec4 czm_computePosition()") {
        forwardDecl += functionName + ";\n";
      }

      if (!defined(primitive.rtcCenter)) {
        // Use GPU RTE
        if (!scene3DOnly) {
          attributes +=
            "attribute vec3 " +
            name +
            "2DHigh;\n" +
            "attribute vec3 " +
            name +
            "2DLow;\n";

          computeFunctions +=
            functionName +
            "\n" +
            "{\n" +
            "    vec4 p;\n" +
            "    if (czm_morphTime == 1.0)\n" +
            "    {\n" +
            "        p = czm_translateRelativeToEye(" +
            name +
            "3DHigh, " +
            name +
            "3DLow);\n" +
            "    }\n" +
            "    else if (czm_morphTime == 0.0)\n" +
            "    {\n" +
            "        p = czm_translateRelativeToEye(" +
            name +
            "2DHigh.zxy, " +
            name +
            "2DLow.zxy);\n" +
            "    }\n" +
            "    else\n" +
            "    {\n" +
            "        p = czm_columbusViewMorph(\n" +
            "                czm_translateRelativeToEye(" +
            name +
            "2DHigh.zxy, " +
            name +
            "2DLow.zxy),\n" +
            "                czm_translateRelativeToEye(" +
            name +
            "3DHigh, " +
            name +
            "3DLow),\n" +
            "                czm_morphTime);\n" +
            "    }\n" +
            "    return p;\n" +
            "}\n\n";
        } else {
          computeFunctions +=
            functionName +
            "\n" +
            "{\n" +
            "    return czm_translateRelativeToEye(" +
            name +
            "3DHigh, " +
            name +
            "3DLow);\n" +
            "}\n\n";
        }
      } else {
        // Use RTC
        vertexShaderSource = vertexShaderSource.replace(
          /attribute\s+vec(?:3|4)\s+position3DHigh;/g,
          ""
        );
        vertexShaderSource = vertexShaderSource.replace(
          /attribute\s+vec(?:3|4)\s+position3DLow;/g,
          ""
        );

        forwardDecl += "uniform mat4 u_modifiedModelView;\n";
        attributes += "attribute vec4 position;\n";

        computeFunctions +=
          functionName +
          "\n" +
          "{\n" +
          "    return u_modifiedModelView * position;\n" +
          "}\n\n";

        vertexShaderSource = vertexShaderSource.replace(
          /czm_modelViewRelativeToEye\s+\*\s+/g,
          ""
        );
        vertexShaderSource = vertexShaderSource.replace(
          /czm_modelViewProjectionRelativeToEye/g,
          "czm_projection"
        );
      }
    }

    return [forwardDecl, attributes, vertexShaderSource, computeFunctions].join(
      "\n"
    );
  };

  Primitive._appendShowToShader = function (primitive, vertexShaderSource) {
    if (!defined(primitive._batchTableAttributeIndices.show)) {
      return vertexShaderSource;
    }

    var renamedVS = ShaderSource.replaceMain(
      vertexShaderSource,
      "czm_non_show_main"
    );
    var showMain =
      "void main() \n" +
      "{ \n" +
      "    czm_non_show_main(); \n" +
      "    gl_Position *= czm_batchTable_show(batchId); \n" +
      "}";

    return renamedVS + "\n" + showMain;
  };

  Primitive._updateColorAttribute = function (
    primitive,
    vertexShaderSource,
    isDepthFail
  ) {
    // some appearances have a color attribute for per vertex color.
    // only remove if color is a per instance attribute.
    if (
      !defined(primitive._batchTableAttributeIndices.color) &&
      !defined(primitive._batchTableAttributeIndices.depthFailColor)
    ) {
      return vertexShaderSource;
    }

    if (vertexShaderSource.search(/attribute\s+vec4\s+color;/g) === -1) {
      return vertexShaderSource;
    }

    //>>includeStart('debug', pragmas.debug);
    if (
      isDepthFail &&
      !defined(primitive._batchTableAttributeIndices.depthFailColor)
    ) {
      throw new DeveloperError(
        "A depthFailColor per-instance attribute is required when using a depth fail appearance that uses a color attribute."
      );
    }
    //>>includeEnd('debug');

    var modifiedVS = vertexShaderSource;
    modifiedVS = modifiedVS.replace(/attribute\s+vec4\s+color;/g, "");
    if (!isDepthFail) {
      modifiedVS = modifiedVS.replace(
        /(\b)color(\b)/g,
        "$1czm_batchTable_color(batchId)$2"
      );
    } else {
      modifiedVS = modifiedVS.replace(
        /(\b)color(\b)/g,
        "$1czm_batchTable_depthFailColor(batchId)$2"
      );
    }
    return modifiedVS;
  };

  function appendPickToVertexShader(source) {
    var renamedVS = ShaderSource.replaceMain(source, "czm_non_pick_main");
    var pickMain =
      "varying vec4 v_pickColor; \n" +
      "void main() \n" +
      "{ \n" +
      "    czm_non_pick_main(); \n" +
      "    v_pickColor = czm_batchTable_pickColor(batchId); \n" +
      "}";

    return renamedVS + "\n" + pickMain;
  }

  function appendPickToFragmentShader(source) {
    return "varying vec4 v_pickColor;\n" + source;
  }

  Primitive._updatePickColorAttribute = function (source) {
    var vsPick = source.replace(/attribute\s+vec4\s+pickColor;/g, "");
    vsPick = vsPick.replace(
      /(\b)pickColor(\b)/g,
      "$1czm_batchTable_pickColor(batchId)$2"
    );
    return vsPick;
  };

  Primitive._appendOffsetToShader = function (primitive, vertexShaderSource) {
    if (!defined(primitive._batchTableAttributeIndices.offset)) {
      return vertexShaderSource;
    }

    var attr = "attribute float batchId;\n";
    attr += "attribute float applyOffset;";
    var modifiedShader = vertexShaderSource.replace(
      /attribute\s+float\s+batchId;/g,
      attr
    );

    var str = "vec4 $1 = czm_computePosition();\n";
    str += "    if (czm_sceneMode == czm_sceneMode3D)\n";
    str += "    {\n";
    str +=
      "        $1 = $1 + vec4(czm_batchTable_offset(batchId) * applyOffset, 0.0);";
    str += "    }\n";
    str += "    else\n";
    str += "    {\n";
    str +=
      "        $1 = $1 + vec4(czm_batchTable_offset2D(batchId) * applyOffset, 0.0);";
    str += "    }\n";
    modifiedShader = modifiedShader.replace(
      /vec4\s+([A-Za-z0-9_]+)\s+=\s+czm_computePosition\(\);/g,
      str
    );
    return modifiedShader;
  };

  Primitive._appendDistanceDisplayConditionToShader = function (
    primitive,
    vertexShaderSource,
    scene3DOnly
  ) {
    if (
      !defined(primitive._batchTableAttributeIndices.distanceDisplayCondition)
    ) {
      return vertexShaderSource;
    }

    var renamedVS = ShaderSource.replaceMain(
      vertexShaderSource,
      "czm_non_distanceDisplayCondition_main"
    );
    var distanceDisplayConditionMain =
      "void main() \n" +
      "{ \n" +
      "    czm_non_distanceDisplayCondition_main(); \n" +
      "    vec2 distanceDisplayCondition = czm_batchTable_distanceDisplayCondition(batchId);\n" +
      "    vec3 boundingSphereCenter3DHigh = czm_batchTable_boundingSphereCenter3DHigh(batchId);\n" +
      "    vec3 boundingSphereCenter3DLow = czm_batchTable_boundingSphereCenter3DLow(batchId);\n" +
      "    float boundingSphereRadius = czm_batchTable_boundingSphereRadius(batchId);\n";

    if (!scene3DOnly) {
      distanceDisplayConditionMain +=
        "    vec3 boundingSphereCenter2DHigh = czm_batchTable_boundingSphereCenter2DHigh(batchId);\n" +
        "    vec3 boundingSphereCenter2DLow = czm_batchTable_boundingSphereCenter2DLow(batchId);\n" +
        "    vec4 centerRTE;\n" +
        "    if (czm_morphTime == 1.0)\n" +
        "    {\n" +
        "        centerRTE = czm_translateRelativeToEye(boundingSphereCenter3DHigh, boundingSphereCenter3DLow);\n" +
        "    }\n" +
        "    else if (czm_morphTime == 0.0)\n" +
        "    {\n" +
        "        centerRTE = czm_translateRelativeToEye(boundingSphereCenter2DHigh.zxy, boundingSphereCenter2DLow.zxy);\n" +
        "    }\n" +
        "    else\n" +
        "    {\n" +
        "        centerRTE = czm_columbusViewMorph(\n" +
        "                czm_translateRelativeToEye(boundingSphereCenter2DHigh.zxy, boundingSphereCenter2DLow.zxy),\n" +
        "                czm_translateRelativeToEye(boundingSphereCenter3DHigh, boundingSphereCenter3DLow),\n" +
        "                czm_morphTime);\n" +
        "    }\n";
    } else {
      distanceDisplayConditionMain +=
        "    vec4 centerRTE = czm_translateRelativeToEye(boundingSphereCenter3DHigh, boundingSphereCenter3DLow);\n";
    }

    distanceDisplayConditionMain +=
      "    float radiusSq = boundingSphereRadius * boundingSphereRadius; \n" +
      "    float distanceSq; \n" +
      "    if (czm_sceneMode == czm_sceneMode2D) \n" +
      "    { \n" +
      "        distanceSq = czm_eyeHeight2D.y - radiusSq; \n" +
      "    } \n" +
      "    else \n" +
      "    { \n" +
      "        distanceSq = dot(centerRTE.xyz, centerRTE.xyz) - radiusSq; \n" +
      "    } \n" +
      "    distanceSq = max(distanceSq, 0.0); \n" +
      "    float nearSq = distanceDisplayCondition.x * distanceDisplayCondition.x; \n" +
      "    float farSq = distanceDisplayCondition.y * distanceDisplayCondition.y; \n" +
      "    float show = (distanceSq >= nearSq && distanceSq <= farSq) ? 1.0 : 0.0; \n" +
      "    gl_Position *= show; \n" +
      "}";
    return renamedVS + "\n" + distanceDisplayConditionMain;
  };

  function modifyForEncodedNormals(primitive, vertexShaderSource) {
    if (!primitive.compressVertices) {
      return vertexShaderSource;
    }

    var containsNormal =
      vertexShaderSource.search(/attribute\s+vec3\s+normal;/g) !== -1;
    var containsSt = vertexShaderSource.search(/attribute\s+vec2\s+st;/g) !== -1;
    if (!containsNormal && !containsSt) {
      return vertexShaderSource;
    }

    var containsTangent =
      vertexShaderSource.search(/attribute\s+vec3\s+tangent;/g) !== -1;
    var containsBitangent =
      vertexShaderSource.search(/attribute\s+vec3\s+bitangent;/g) !== -1;

    var numComponents = containsSt && containsNormal ? 2.0 : 1.0;
    numComponents += containsTangent || containsBitangent ? 1 : 0;

    var type = numComponents > 1 ? "vec" + numComponents : "float";

    var attributeName = "compressedAttributes";
    var attributeDecl = "attribute " + type + " " + attributeName + ";";

    var globalDecl = "";
    var decode = "";

    if (containsSt) {
      globalDecl += "vec2 st;\n";
      var stComponent = numComponents > 1 ? attributeName + ".x" : attributeName;
      decode +=
        "    st = czm_decompressTextureCoordinates(" + stComponent + ");\n";
    }

    if (containsNormal && containsTangent && containsBitangent) {
      globalDecl += "vec3 normal;\n" + "vec3 tangent;\n" + "vec3 bitangent;\n";
      decode +=
        "    czm_octDecode(" +
        attributeName +
        "." +
        (containsSt ? "yz" : "xy") +
        ", normal, tangent, bitangent);\n";
    } else {
      if (containsNormal) {
        globalDecl += "vec3 normal;\n";
        decode +=
          "    normal = czm_octDecode(" +
          attributeName +
          (numComponents > 1 ? "." + (containsSt ? "y" : "x") : "") +
          ");\n";
      }

      if (containsTangent) {
        globalDecl += "vec3 tangent;\n";
        decode +=
          "    tangent = czm_octDecode(" +
          attributeName +
          "." +
          (containsSt && containsNormal ? "z" : "y") +
          ");\n";
      }

      if (containsBitangent) {
        globalDecl += "vec3 bitangent;\n";
        decode +=
          "    bitangent = czm_octDecode(" +
          attributeName +
          "." +
          (containsSt && containsNormal ? "z" : "y") +
          ");\n";
      }
    }

    var modifiedVS = vertexShaderSource;
    modifiedVS = modifiedVS.replace(/attribute\s+vec3\s+normal;/g, "");
    modifiedVS = modifiedVS.replace(/attribute\s+vec2\s+st;/g, "");
    modifiedVS = modifiedVS.replace(/attribute\s+vec3\s+tangent;/g, "");
    modifiedVS = modifiedVS.replace(/attribute\s+vec3\s+bitangent;/g, "");
    modifiedVS = ShaderSource.replaceMain(modifiedVS, "czm_non_compressed_main");
    var compressedMain =
      "void main() \n" +
      "{ \n" +
      decode +
      "    czm_non_compressed_main(); \n" +
      "}";

    return [attributeDecl, globalDecl, modifiedVS, compressedMain].join("\n");
  }

  function depthClampVS(vertexShaderSource) {
    var modifiedVS = ShaderSource.replaceMain(
      vertexShaderSource,
      "czm_non_depth_clamp_main"
    );
    modifiedVS +=
      "void main() {\n" +
      "    czm_non_depth_clamp_main();\n" +
      "    gl_Position = czm_depthClamp(gl_Position);" +
      "}\n";
    return modifiedVS;
  }

  function depthClampFS(fragmentShaderSource) {
    var modifiedFS = ShaderSource.replaceMain(
      fragmentShaderSource,
      "czm_non_depth_clamp_main"
    );
    modifiedFS +=
      "void main() {\n" +
      "    czm_non_depth_clamp_main();\n" +
      "#if defined(GL_EXT_frag_depth)\n" +
      "    #if defined(LOG_DEPTH)\n" +
      "        czm_writeLogDepth();\n" +
      "    #else\n" +
      "        czm_writeDepthClamp();\n" +
      "    #endif\n" +
      "#endif\n" +
      "}\n";
    modifiedFS =
      "#ifdef GL_EXT_frag_depth\n" +
      "#extension GL_EXT_frag_depth : enable\n" +
      "#endif\n" +
      modifiedFS;
    return modifiedFS;
  }

  function validateShaderMatching(shaderProgram, attributeLocations) {
    // For a VAO and shader program to be compatible, the VAO must have
    // all active attribute in the shader program.  The VAO may have
    // extra attributes with the only concern being a potential
    // performance hit due to extra memory bandwidth and cache pollution.
    // The shader source could have extra attributes that are not used,
    // but there is no guarantee they will be optimized out.
    //
    // Here, we validate that the VAO has all attributes required
    // to match the shader program.
    var shaderAttributes = shaderProgram.vertexAttributes;

    //>>includeStart('debug', pragmas.debug);
    for (var name in shaderAttributes) {
      if (shaderAttributes.hasOwnProperty(name)) {
        if (!defined(attributeLocations[name])) {
          throw new DeveloperError(
            "Appearance/Geometry mismatch.  The appearance requires vertex shader attribute input '" +
              name +
              "', which was not computed as part of the Geometry.  Use the appearance's vertexFormat property when constructing the geometry."
          );
        }
      }
    }
    //>>includeEnd('debug');
  }

  function getUniformFunction(uniforms, name) {
    return function () {
      return uniforms[name];
    };
  }

  var numberOfCreationWorkers = Math.max(
    FeatureDetection.hardwareConcurrency - 1,
    1
  );
  var createGeometryTaskProcessors;
  var combineGeometryTaskProcessor = new TaskProcessor(
    "combineGeometry",
    Number.POSITIVE_INFINITY
  );

  function loadAsynchronous(primitive, frameState) {
    var instances;
    var geometry;
    var i;
    var j;

    var instanceIds = primitive._instanceIds;

    if (primitive._state === PrimitiveState$1.READY) {
      instances = Array.isArray(primitive.geometryInstances)
        ? primitive.geometryInstances
        : [primitive.geometryInstances];
      var length = (primitive._numberOfInstances = instances.length);

      var promises = [];
      var subTasks = [];
      for (i = 0; i < length; ++i) {
        geometry = instances[i].geometry;
        instanceIds.push(instances[i].id);

        //>>includeStart('debug', pragmas.debug);
        if (!defined(geometry._workerName)) {
          throw new DeveloperError(
            "_workerName must be defined for asynchronous geometry."
          );
        }
        //>>includeEnd('debug');

        subTasks.push({
          moduleName: geometry._workerName,
          geometry: geometry,
        });
      }

      if (!defined(createGeometryTaskProcessors)) {
        createGeometryTaskProcessors = new Array(numberOfCreationWorkers);
        for (i = 0; i < numberOfCreationWorkers; i++) {
          createGeometryTaskProcessors[i] = new TaskProcessor(
            "createGeometry",
            Number.POSITIVE_INFINITY
          );
        }
      }

      var subTask;
      subTasks = subdivideArray(subTasks, numberOfCreationWorkers);

      for (i = 0; i < subTasks.length; i++) {
        var packedLength = 0;
        var workerSubTasks = subTasks[i];
        var workerSubTasksLength = workerSubTasks.length;
        for (j = 0; j < workerSubTasksLength; ++j) {
          subTask = workerSubTasks[j];
          geometry = subTask.geometry;
          if (defined(geometry.constructor.pack)) {
            subTask.offset = packedLength;
            packedLength += defaultValue(
              geometry.constructor.packedLength,
              geometry.packedLength
            );
          }
        }

        var subTaskTransferableObjects;

        if (packedLength > 0) {
          var array = new Float64Array(packedLength);
          subTaskTransferableObjects = [array.buffer];

          for (j = 0; j < workerSubTasksLength; ++j) {
            subTask = workerSubTasks[j];
            geometry = subTask.geometry;
            if (defined(geometry.constructor.pack)) {
              geometry.constructor.pack(geometry, array, subTask.offset);
              subTask.geometry = array;
            }
          }
        }

        promises.push(
          createGeometryTaskProcessors[i].scheduleTask(
            {
              subTasks: subTasks[i],
            },
            subTaskTransferableObjects
          )
        );
      }

      primitive._state = PrimitiveState$1.CREATING;

      when
        .all(promises, function (results) {
          primitive._createGeometryResults = results;
          primitive._state = PrimitiveState$1.CREATED;
        })
        .otherwise(function (error) {
          setReady(primitive, frameState, PrimitiveState$1.FAILED, error);
        });
    } else if (primitive._state === PrimitiveState$1.CREATED) {
      var transferableObjects = [];
      instances = Array.isArray(primitive.geometryInstances)
        ? primitive.geometryInstances
        : [primitive.geometryInstances];

      var scene3DOnly = frameState.scene3DOnly;
      var projection = frameState.mapProjection;

      var promise = combineGeometryTaskProcessor.scheduleTask(
        PrimitivePipeline.packCombineGeometryParameters(
          {
            createGeometryResults: primitive._createGeometryResults,
            instances: instances,
            ellipsoid: projection.ellipsoid,
            projection: projection,
            elementIndexUintSupported: frameState.context.elementIndexUint,
            scene3DOnly: scene3DOnly,
            vertexCacheOptimize: primitive.vertexCacheOptimize,
            compressVertices: primitive.compressVertices,
            modelMatrix: primitive.modelMatrix,
            createPickOffsets: primitive._createPickOffsets,
          },
          transferableObjects
        ),
        transferableObjects
      );

      primitive._createGeometryResults = undefined;
      primitive._state = PrimitiveState$1.COMBINING;

      when(promise, function (packedResult) {
        var result = PrimitivePipeline.unpackCombineGeometryResults(packedResult);
        primitive._geometries = result.geometries;
        primitive._attributeLocations = result.attributeLocations;
        primitive.modelMatrix = Matrix4.clone(
          result.modelMatrix,
          primitive.modelMatrix
        );
        primitive._pickOffsets = result.pickOffsets;
        primitive._offsetInstanceExtend = result.offsetInstanceExtend;
        primitive._instanceBoundingSpheres = result.boundingSpheres;
        primitive._instanceBoundingSpheresCV = result.boundingSpheresCV;

        if (defined(primitive._geometries) && primitive._geometries.length > 0) {
          primitive._recomputeBoundingSpheres = true;
          primitive._state = PrimitiveState$1.COMBINED;
        } else {
          setReady(primitive, frameState, PrimitiveState$1.FAILED, undefined);
        }
      }).otherwise(function (error) {
        setReady(primitive, frameState, PrimitiveState$1.FAILED, error);
      });
    }
  }

  function loadSynchronous(primitive, frameState) {
    var instances = Array.isArray(primitive.geometryInstances)
      ? primitive.geometryInstances
      : [primitive.geometryInstances];
    var length = (primitive._numberOfInstances = instances.length);
    var clonedInstances = new Array(length);
    var instanceIds = primitive._instanceIds;

    var instance;
    var i;

    var geometryIndex = 0;
    for (i = 0; i < length; i++) {
      instance = instances[i];
      var geometry = instance.geometry;

      var createdGeometry;
      if (defined(geometry.attributes) && defined(geometry.primitiveType)) {
        createdGeometry = cloneGeometry(geometry);
      } else {
        createdGeometry = geometry.constructor.createGeometry(geometry);
      }

      clonedInstances[geometryIndex++] = cloneInstance(instance, createdGeometry);
      instanceIds.push(instance.id);
    }

    clonedInstances.length = geometryIndex;

    var scene3DOnly = frameState.scene3DOnly;
    var projection = frameState.mapProjection;

    var result = PrimitivePipeline.combineGeometry({
      instances: clonedInstances,
      ellipsoid: projection.ellipsoid,
      projection: projection,
      elementIndexUintSupported: frameState.context.elementIndexUint,
      scene3DOnly: scene3DOnly,
      vertexCacheOptimize: primitive.vertexCacheOptimize,
      compressVertices: primitive.compressVertices,
      modelMatrix: primitive.modelMatrix,
      createPickOffsets: primitive._createPickOffsets,
    });

    primitive._geometries = result.geometries;
    primitive._attributeLocations = result.attributeLocations;
    primitive.modelMatrix = Matrix4.clone(
      result.modelMatrix,
      primitive.modelMatrix
    );
    primitive._pickOffsets = result.pickOffsets;
    primitive._offsetInstanceExtend = result.offsetInstanceExtend;
    primitive._instanceBoundingSpheres = result.boundingSpheres;
    primitive._instanceBoundingSpheresCV = result.boundingSpheresCV;

    if (defined(primitive._geometries) && primitive._geometries.length > 0) {
      primitive._recomputeBoundingSpheres = true;
      primitive._state = PrimitiveState$1.COMBINED;
    } else {
      setReady(primitive, frameState, PrimitiveState$1.FAILED, undefined);
    }
  }

  function recomputeBoundingSpheres(primitive, frameState) {
    var offsetIndex = primitive._batchTableAttributeIndices.offset;
    if (!primitive._recomputeBoundingSpheres || !defined(offsetIndex)) {
      primitive._recomputeBoundingSpheres = false;
      return;
    }

    var i;
    var offsetInstanceExtend = primitive._offsetInstanceExtend;
    var boundingSpheres = primitive._instanceBoundingSpheres;
    var length = boundingSpheres.length;
    var newBoundingSpheres = primitive._tempBoundingSpheres;
    if (!defined(newBoundingSpheres)) {
      newBoundingSpheres = new Array(length);
      for (i = 0; i < length; i++) {
        newBoundingSpheres[i] = new BoundingSphere();
      }
      primitive._tempBoundingSpheres = newBoundingSpheres;
    }
    for (i = 0; i < length; ++i) {
      var newBS = newBoundingSpheres[i];
      var offset = primitive._batchTable.getBatchedAttribute(
        i,
        offsetIndex,
        new Cartesian3()
      );
      newBS = boundingSpheres[i].clone(newBS);
      transformBoundingSphere(newBS, offset, offsetInstanceExtend[i]);
    }
    var combinedBS = [];
    var combinedWestBS = [];
    var combinedEastBS = [];

    for (i = 0; i < length; ++i) {
      var bs = newBoundingSpheres[i];

      var minX = bs.center.x - bs.radius;
      if (
        minX > 0 ||
        BoundingSphere.intersectPlane(bs, Plane.ORIGIN_ZX_PLANE) !==
          Intersect$1.INTERSECTING
      ) {
        combinedBS.push(bs);
      } else {
        combinedWestBS.push(bs);
        combinedEastBS.push(bs);
      }
    }

    var resultBS1 = combinedBS[0];
    var resultBS2 = combinedEastBS[0];
    var resultBS3 = combinedWestBS[0];

    for (i = 1; i < combinedBS.length; i++) {
      resultBS1 = BoundingSphere.union(resultBS1, combinedBS[i]);
    }
    for (i = 1; i < combinedEastBS.length; i++) {
      resultBS2 = BoundingSphere.union(resultBS2, combinedEastBS[i]);
    }
    for (i = 1; i < combinedWestBS.length; i++) {
      resultBS3 = BoundingSphere.union(resultBS3, combinedWestBS[i]);
    }
    var result = [];
    if (defined(resultBS1)) {
      result.push(resultBS1);
    }
    if (defined(resultBS2)) {
      result.push(resultBS2);
    }
    if (defined(resultBS3)) {
      result.push(resultBS3);
    }

    for (i = 0; i < result.length; i++) {
      var boundingSphere = result[i].clone(primitive._boundingSpheres[i]);
      primitive._boundingSpheres[i] = boundingSphere;
      primitive._boundingSphereCV[i] = BoundingSphere.projectTo2D(
        boundingSphere,
        frameState.mapProjection,
        primitive._boundingSphereCV[i]
      );
    }

    Primitive._updateBoundingVolumes(
      primitive,
      frameState,
      primitive.modelMatrix,
      true
    );
    primitive._recomputeBoundingSpheres = false;
  }

  var scratchBoundingSphereCenterEncoded = new EncodedCartesian3();
  var scratchBoundingSphereCartographic = new Cartographic();
  var scratchBoundingSphereCenter2D = new Cartesian3();
  var scratchBoundingSphere$2 = new BoundingSphere();

  function updateBatchTableBoundingSpheres(primitive, frameState) {
    var hasDistanceDisplayCondition = defined(
      primitive._batchTableAttributeIndices.distanceDisplayCondition
    );
    if (
      !hasDistanceDisplayCondition ||
      primitive._batchTableBoundingSpheresUpdated
    ) {
      return;
    }

    var indices = primitive._batchTableBoundingSphereAttributeIndices;
    var center3DHighIndex = indices.center3DHigh;
    var center3DLowIndex = indices.center3DLow;
    var center2DHighIndex = indices.center2DHigh;
    var center2DLowIndex = indices.center2DLow;
    var radiusIndex = indices.radius;

    var projection = frameState.mapProjection;
    var ellipsoid = projection.ellipsoid;

    var batchTable = primitive._batchTable;
    var boundingSpheres = primitive._instanceBoundingSpheres;
    var length = boundingSpheres.length;

    for (var i = 0; i < length; ++i) {
      var boundingSphere = boundingSpheres[i];
      if (!defined(boundingSphere)) {
        continue;
      }

      var modelMatrix = primitive.modelMatrix;
      if (defined(modelMatrix)) {
        boundingSphere = BoundingSphere.transform(
          boundingSphere,
          modelMatrix,
          scratchBoundingSphere$2
        );
      }

      var center = boundingSphere.center;
      var radius = boundingSphere.radius;

      var encodedCenter = EncodedCartesian3.fromCartesian(
        center,
        scratchBoundingSphereCenterEncoded
      );
      batchTable.setBatchedAttribute(i, center3DHighIndex, encodedCenter.high);
      batchTable.setBatchedAttribute(i, center3DLowIndex, encodedCenter.low);

      if (!frameState.scene3DOnly) {
        var cartographic = ellipsoid.cartesianToCartographic(
          center,
          scratchBoundingSphereCartographic
        );
        var center2D = projection.project(
          cartographic,
          scratchBoundingSphereCenter2D
        );
        encodedCenter = EncodedCartesian3.fromCartesian(
          center2D,
          scratchBoundingSphereCenterEncoded
        );
        batchTable.setBatchedAttribute(i, center2DHighIndex, encodedCenter.high);
        batchTable.setBatchedAttribute(i, center2DLowIndex, encodedCenter.low);
      }

      batchTable.setBatchedAttribute(i, radiusIndex, radius);
    }

    primitive._batchTableBoundingSpheresUpdated = true;
  }

  var offsetScratchCartesian = new Cartesian3();
  var offsetCenterScratch = new Cartesian3();
  function updateBatchTableOffsets(primitive, frameState) {
    var hasOffset = defined(primitive._batchTableAttributeIndices.offset);
    if (
      !hasOffset ||
      primitive._batchTableOffsetsUpdated ||
      frameState.scene3DOnly
    ) {
      return;
    }

    var index2D = primitive._batchTableOffsetAttribute2DIndex;

    var projection = frameState.mapProjection;
    var ellipsoid = projection.ellipsoid;

    var batchTable = primitive._batchTable;
    var boundingSpheres = primitive._instanceBoundingSpheres;
    var length = boundingSpheres.length;

    for (var i = 0; i < length; ++i) {
      var boundingSphere = boundingSpheres[i];
      if (!defined(boundingSphere)) {
        continue;
      }
      var offset = batchTable.getBatchedAttribute(
        i,
        primitive._batchTableAttributeIndices.offset
      );
      if (Cartesian3.equals(offset, Cartesian3.ZERO)) {
        batchTable.setBatchedAttribute(i, index2D, Cartesian3.ZERO);
        continue;
      }

      var modelMatrix = primitive.modelMatrix;
      if (defined(modelMatrix)) {
        boundingSphere = BoundingSphere.transform(
          boundingSphere,
          modelMatrix,
          scratchBoundingSphere$2
        );
      }

      var center = boundingSphere.center;
      center = ellipsoid.scaleToGeodeticSurface(center, offsetCenterScratch);
      var cartographic = ellipsoid.cartesianToCartographic(
        center,
        scratchBoundingSphereCartographic
      );
      var center2D = projection.project(
        cartographic,
        scratchBoundingSphereCenter2D
      );

      var newPoint = Cartesian3.add(offset, center, offsetScratchCartesian);
      cartographic = ellipsoid.cartesianToCartographic(newPoint, cartographic);

      var newPointProjected = projection.project(
        cartographic,
        offsetScratchCartesian
      );

      var newVector = Cartesian3.subtract(
        newPointProjected,
        center2D,
        offsetScratchCartesian
      );

      var x = newVector.x;
      newVector.x = newVector.z;
      newVector.z = newVector.y;
      newVector.y = x;

      batchTable.setBatchedAttribute(i, index2D, newVector);
    }

    primitive._batchTableOffsetsUpdated = true;
  }

  function createVertexArray(primitive, frameState) {
    var attributeLocations = primitive._attributeLocations;
    var geometries = primitive._geometries;
    var scene3DOnly = frameState.scene3DOnly;
    var context = frameState.context;

    var va = [];
    var length = geometries.length;
    for (var i = 0; i < length; ++i) {
      var geometry = geometries[i];

      va.push(
        VertexArray.fromGeometry({
          context: context,
          geometry: geometry,
          attributeLocations: attributeLocations,
          bufferUsage: BufferUsage$1.STATIC_DRAW,
          interleave: primitive._interleave,
        })
      );

      if (defined(primitive._createBoundingVolumeFunction)) {
        primitive._createBoundingVolumeFunction(frameState, geometry);
      } else {
        primitive._boundingSpheres.push(
          BoundingSphere.clone(geometry.boundingSphere)
        );
        primitive._boundingSphereWC.push(new BoundingSphere());

        if (!scene3DOnly) {
          var center = geometry.boundingSphereCV.center;
          var x = center.x;
          var y = center.y;
          var z = center.z;
          center.x = z;
          center.y = x;
          center.z = y;

          primitive._boundingSphereCV.push(
            BoundingSphere.clone(geometry.boundingSphereCV)
          );
          primitive._boundingSphere2D.push(new BoundingSphere());
          primitive._boundingSphereMorph.push(new BoundingSphere());
        }
      }
    }

    primitive._va = va;
    primitive._primitiveType = geometries[0].primitiveType;

    if (primitive.releaseGeometryInstances) {
      primitive.geometryInstances = undefined;
    }

    primitive._geometries = undefined;
    setReady(primitive, frameState, PrimitiveState$1.COMPLETE, undefined);
  }

  function createRenderStates(primitive, context, appearance, twoPasses) {
    var renderState = appearance.getRenderState();
    var rs;

    if (twoPasses) {
      rs = clone(renderState, false);
      rs.cull = {
        enabled: true,
        face: CullFace$1.BACK,
      };
      primitive._frontFaceRS = RenderState.fromCache(rs);

      rs.cull.face = CullFace$1.FRONT;
      primitive._backFaceRS = RenderState.fromCache(rs);
    } else {
      primitive._frontFaceRS = RenderState.fromCache(renderState);
      primitive._backFaceRS = primitive._frontFaceRS;
    }

    rs = clone(renderState, false);
    if (defined(primitive._depthFailAppearance)) {
      rs.depthTest.enabled = false;
    }

    if (defined(primitive._depthFailAppearance)) {
      renderState = primitive._depthFailAppearance.getRenderState();
      rs = clone(renderState, false);
      rs.depthTest.func = DepthFunction$1.GREATER;
      if (twoPasses) {
        rs.cull = {
          enabled: true,
          face: CullFace$1.BACK,
        };
        primitive._frontFaceDepthFailRS = RenderState.fromCache(rs);

        rs.cull.face = CullFace$1.FRONT;
        primitive._backFaceDepthFailRS = RenderState.fromCache(rs);
      } else {
        primitive._frontFaceDepthFailRS = RenderState.fromCache(rs);
        primitive._backFaceDepthFailRS = primitive._frontFaceRS;
      }
    }
  }

  function createShaderProgram(primitive, frameState, appearance) {
    var context = frameState.context;

    var attributeLocations = primitive._attributeLocations;

    var vs = primitive._batchTable.getVertexShaderCallback()(
      appearance.vertexShaderSource
    );
    vs = Primitive._appendOffsetToShader(primitive, vs);
    vs = Primitive._appendShowToShader(primitive, vs);
    vs = Primitive._appendDistanceDisplayConditionToShader(
      primitive,
      vs,
      frameState.scene3DOnly
    );
    vs = appendPickToVertexShader(vs);
    vs = Primitive._updateColorAttribute(primitive, vs, false);
    vs = modifyForEncodedNormals(primitive, vs);
    vs = Primitive._modifyShaderPosition(primitive, vs, frameState.scene3DOnly);
    var fs = appearance.getFragmentShaderSource();
    fs = appendPickToFragmentShader(fs);

    primitive._sp = ShaderProgram.replaceCache({
      context: context,
      shaderProgram: primitive._sp,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations,
    });
    validateShaderMatching(primitive._sp, attributeLocations);

    if (defined(primitive._depthFailAppearance)) {
      vs = primitive._batchTable.getVertexShaderCallback()(
        primitive._depthFailAppearance.vertexShaderSource
      );
      vs = Primitive._appendShowToShader(primitive, vs);
      vs = Primitive._appendDistanceDisplayConditionToShader(
        primitive,
        vs,
        frameState.scene3DOnly
      );
      vs = appendPickToVertexShader(vs);
      vs = Primitive._updateColorAttribute(primitive, vs, true);
      vs = modifyForEncodedNormals(primitive, vs);
      vs = Primitive._modifyShaderPosition(primitive, vs, frameState.scene3DOnly);
      vs = depthClampVS(vs);

      fs = primitive._depthFailAppearance.getFragmentShaderSource();
      fs = appendPickToFragmentShader(fs);
      fs = depthClampFS(fs);

      primitive._spDepthFail = ShaderProgram.replaceCache({
        context: context,
        shaderProgram: primitive._spDepthFail,
        vertexShaderSource: vs,
        fragmentShaderSource: fs,
        attributeLocations: attributeLocations,
      });
      validateShaderMatching(primitive._spDepthFail, attributeLocations);
    }
  }

  var modifiedModelViewScratch = new Matrix4();
  var rtcScratch = new Cartesian3();

  function getUniforms(primitive, appearance, material, frameState) {
    // Create uniform map by combining uniforms from the appearance and material if either have uniforms.
    var materialUniformMap = defined(material) ? material._uniforms : undefined;
    var appearanceUniformMap = {};
    var appearanceUniforms = appearance.uniforms;
    if (defined(appearanceUniforms)) {
      // Convert to uniform map of functions for the renderer
      for (var name in appearanceUniforms) {
        if (appearanceUniforms.hasOwnProperty(name)) {
          //>>includeStart('debug', pragmas.debug);
          if (defined(materialUniformMap) && defined(materialUniformMap[name])) {
            // Later, we could rename uniforms behind-the-scenes if needed.
            throw new DeveloperError(
              "Appearance and material have a uniform with the same name: " + name
            );
          }
          //>>includeEnd('debug');

          appearanceUniformMap[name] = getUniformFunction(
            appearanceUniforms,
            name
          );
        }
      }
    }
    var uniforms = combine(appearanceUniformMap, materialUniformMap);
    uniforms = primitive._batchTable.getUniformMapCallback()(uniforms);

    if (defined(primitive.rtcCenter)) {
      uniforms.u_modifiedModelView = function () {
        var viewMatrix = frameState.context.uniformState.view;
        Matrix4.multiply(
          viewMatrix,
          primitive._modelMatrix,
          modifiedModelViewScratch
        );
        Matrix4.multiplyByPoint(
          modifiedModelViewScratch,
          primitive.rtcCenter,
          rtcScratch
        );
        Matrix4.setTranslation(
          modifiedModelViewScratch,
          rtcScratch,
          modifiedModelViewScratch
        );
        return modifiedModelViewScratch;
      };
    }

    return uniforms;
  }

  function createCommands(
    primitive,
    appearance,
    material,
    translucent,
    twoPasses,
    colorCommands,
    pickCommands,
    frameState
  ) {
    var uniforms = getUniforms(primitive, appearance, material, frameState);

    var depthFailUniforms;
    if (defined(primitive._depthFailAppearance)) {
      depthFailUniforms = getUniforms(
        primitive,
        primitive._depthFailAppearance,
        primitive._depthFailAppearance.material,
        frameState
      );
    }

    var pass = translucent ? Pass$1.TRANSLUCENT : Pass$1.OPAQUE;

    var multiplier = twoPasses ? 2 : 1;
    multiplier *= defined(primitive._depthFailAppearance) ? 2 : 1;
    colorCommands.length = primitive._va.length * multiplier;

    var length = colorCommands.length;
    var vaIndex = 0;
    for (var i = 0; i < length; ++i) {
      var colorCommand;

      if (twoPasses) {
        colorCommand = colorCommands[i];
        if (!defined(colorCommand)) {
          colorCommand = colorCommands[i] = new DrawCommand({
            owner: primitive,
            primitiveType: primitive._primitiveType,
          });
        }
        colorCommand.vertexArray = primitive._va[vaIndex];
        colorCommand.renderState = primitive._backFaceRS;
        colorCommand.shaderProgram = primitive._sp;
        colorCommand.uniformMap = uniforms;
        colorCommand.pass = pass;

        ++i;
      }

      colorCommand = colorCommands[i];
      if (!defined(colorCommand)) {
        colorCommand = colorCommands[i] = new DrawCommand({
          owner: primitive,
          primitiveType: primitive._primitiveType,
        });
      }
      colorCommand.vertexArray = primitive._va[vaIndex];
      colorCommand.renderState = primitive._frontFaceRS;
      colorCommand.shaderProgram = primitive._sp;
      colorCommand.uniformMap = uniforms;
      colorCommand.pass = pass;

      if (defined(primitive._depthFailAppearance)) {
        if (twoPasses) {
          ++i;

          colorCommand = colorCommands[i];
          if (!defined(colorCommand)) {
            colorCommand = colorCommands[i] = new DrawCommand({
              owner: primitive,
              primitiveType: primitive._primitiveType,
            });
          }
          colorCommand.vertexArray = primitive._va[vaIndex];
          colorCommand.renderState = primitive._backFaceDepthFailRS;
          colorCommand.shaderProgram = primitive._spDepthFail;
          colorCommand.uniformMap = depthFailUniforms;
          colorCommand.pass = pass;
        }

        ++i;

        colorCommand = colorCommands[i];
        if (!defined(colorCommand)) {
          colorCommand = colorCommands[i] = new DrawCommand({
            owner: primitive,
            primitiveType: primitive._primitiveType,
          });
        }
        colorCommand.vertexArray = primitive._va[vaIndex];
        colorCommand.renderState = primitive._frontFaceDepthFailRS;
        colorCommand.shaderProgram = primitive._spDepthFail;
        colorCommand.uniformMap = depthFailUniforms;
        colorCommand.pass = pass;
      }

      ++vaIndex;
    }
  }

  Primitive._updateBoundingVolumes = function (
    primitive,
    frameState,
    modelMatrix,
    forceUpdate
  ) {
    var i;
    var length;
    var boundingSphere;

    if (forceUpdate || !Matrix4.equals(modelMatrix, primitive._modelMatrix)) {
      Matrix4.clone(modelMatrix, primitive._modelMatrix);
      length = primitive._boundingSpheres.length;
      for (i = 0; i < length; ++i) {
        boundingSphere = primitive._boundingSpheres[i];
        if (defined(boundingSphere)) {
          primitive._boundingSphereWC[i] = BoundingSphere.transform(
            boundingSphere,
            modelMatrix,
            primitive._boundingSphereWC[i]
          );
          if (!frameState.scene3DOnly) {
            primitive._boundingSphere2D[i] = BoundingSphere.clone(
              primitive._boundingSphereCV[i],
              primitive._boundingSphere2D[i]
            );
            primitive._boundingSphere2D[i].center.x = 0.0;
            primitive._boundingSphereMorph[i] = BoundingSphere.union(
              primitive._boundingSphereWC[i],
              primitive._boundingSphereCV[i]
            );
          }
        }
      }
    }

    // Update bounding volumes for primitives that are sized in pixels.
    // The pixel size in meters varies based on the distance from the camera.
    var pixelSize = primitive.appearance.pixelSize;
    if (defined(pixelSize)) {
      length = primitive._boundingSpheres.length;
      for (i = 0; i < length; ++i) {
        boundingSphere = primitive._boundingSpheres[i];
        var boundingSphereWC = primitive._boundingSphereWC[i];
        var pixelSizeInMeters = frameState.camera.getPixelSize(
          boundingSphere,
          frameState.context.drawingBufferWidth,
          frameState.context.drawingBufferHeight
        );
        var sizeInMeters = pixelSizeInMeters * pixelSize;
        boundingSphereWC.radius = boundingSphere.radius + sizeInMeters;
      }
    }
  };

  function updateAndQueueCommands(
    primitive,
    frameState,
    colorCommands,
    pickCommands,
    modelMatrix,
    cull,
    debugShowBoundingVolume,
    twoPasses
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (
      frameState.mode !== SceneMode$1.SCENE3D &&
      !Matrix4.equals(modelMatrix, Matrix4.IDENTITY)
    ) {
      throw new DeveloperError(
        "Primitive.modelMatrix is only supported in 3D mode."
      );
    }
    //>>includeEnd('debug');

    Primitive._updateBoundingVolumes(primitive, frameState, modelMatrix);

    var boundingSpheres;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      boundingSpheres = primitive._boundingSphereWC;
    } else if (frameState.mode === SceneMode$1.COLUMBUS_VIEW) {
      boundingSpheres = primitive._boundingSphereCV;
    } else if (
      frameState.mode === SceneMode$1.SCENE2D &&
      defined(primitive._boundingSphere2D)
    ) {
      boundingSpheres = primitive._boundingSphere2D;
    } else if (defined(primitive._boundingSphereMorph)) {
      boundingSpheres = primitive._boundingSphereMorph;
    }

    var commandList = frameState.commandList;
    var passes = frameState.passes;
    if (passes.render || passes.pick) {
      var allowPicking = primitive.allowPicking;
      var castShadows = ShadowMode$1.castShadows(primitive.shadows);
      var receiveShadows = ShadowMode$1.receiveShadows(primitive.shadows);
      var colorLength = colorCommands.length;

      var factor = twoPasses ? 2 : 1;
      factor *= defined(primitive._depthFailAppearance) ? 2 : 1;

      for (var j = 0; j < colorLength; ++j) {
        var sphereIndex = Math.floor(j / factor);
        var colorCommand = colorCommands[j];
        colorCommand.modelMatrix = modelMatrix;
        colorCommand.boundingVolume = boundingSpheres[sphereIndex];
        colorCommand.cull = cull;
        colorCommand.debugShowBoundingVolume = debugShowBoundingVolume;
        colorCommand.castShadows = castShadows;
        colorCommand.receiveShadows = receiveShadows;

        if (allowPicking) {
          colorCommand.pickId = "v_pickColor";
        } else {
          colorCommand.pickId = undefined;
        }

        commandList.push(colorCommand);
      }
    }
  }

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} All instance geometries must have the same primitiveType.
   * @exception {DeveloperError} Appearance and material have a uniform with the same name.
   * @exception {DeveloperError} Primitive.modelMatrix is only supported in 3D mode.
   * @exception {RuntimeError} Vertex texture fetch support is required to render primitives with per-instance attributes. The maximum number of vertex texture image units must be greater than zero.
   */
  Primitive.prototype.update = function (frameState) {
    if (
      (!defined(this.geometryInstances) && this._va.length === 0) ||
      (defined(this.geometryInstances) &&
        Array.isArray(this.geometryInstances) &&
        this.geometryInstances.length === 0) ||
      !defined(this.appearance) ||
      (frameState.mode !== SceneMode$1.SCENE3D && frameState.scene3DOnly) ||
      (!frameState.passes.render && !frameState.passes.pick)
    ) {
      return;
    }

    if (defined(this._error)) {
      throw this._error;
    }

    //>>includeStart('debug', pragmas.debug);
    if (defined(this.rtcCenter) && !frameState.scene3DOnly) {
      throw new DeveloperError(
        "RTC rendering is only available for 3D only scenes."
      );
    }
    //>>includeEnd('debug');

    if (this._state === PrimitiveState$1.FAILED) {
      return;
    }

    var context = frameState.context;
    if (!defined(this._batchTable)) {
      createBatchTable(this, context);
    }
    if (this._batchTable.attributes.length > 0) {
      if (ContextLimits.maximumVertexTextureImageUnits === 0) {
        throw new RuntimeError(
          "Vertex texture fetch support is required to render primitives with per-instance attributes. The maximum number of vertex texture image units must be greater than zero."
        );
      }
      this._batchTable.update(frameState);
    }

    if (
      this._state !== PrimitiveState$1.COMPLETE &&
      this._state !== PrimitiveState$1.COMBINED
    ) {
      if (this.asynchronous) {
        loadAsynchronous(this, frameState);
      } else {
        loadSynchronous(this, frameState);
      }
    }

    if (this._state === PrimitiveState$1.COMBINED) {
      updateBatchTableBoundingSpheres(this, frameState);
      updateBatchTableOffsets(this, frameState);
      createVertexArray(this, frameState);
    }

    if (!this.show || this._state !== PrimitiveState$1.COMPLETE) {
      return;
    }

    if (!this._batchTableOffsetsUpdated) {
      updateBatchTableOffsets(this, frameState);
    }
    if (this._recomputeBoundingSpheres) {
      recomputeBoundingSpheres(this, frameState);
    }

    // Create or recreate render state and shader program if appearance/material changed
    var appearance = this.appearance;
    var material = appearance.material;
    var createRS = false;
    var createSP = false;

    if (this._appearance !== appearance) {
      this._appearance = appearance;
      this._material = material;
      createRS = true;
      createSP = true;
    } else if (this._material !== material) {
      this._material = material;
      createSP = true;
    }

    var depthFailAppearance = this.depthFailAppearance;
    var depthFailMaterial = defined(depthFailAppearance)
      ? depthFailAppearance.material
      : undefined;

    if (this._depthFailAppearance !== depthFailAppearance) {
      this._depthFailAppearance = depthFailAppearance;
      this._depthFailMaterial = depthFailMaterial;
      createRS = true;
      createSP = true;
    } else if (this._depthFailMaterial !== depthFailMaterial) {
      this._depthFailMaterial = depthFailMaterial;
      createSP = true;
    }

    var translucent = this._appearance.isTranslucent();
    if (this._translucent !== translucent) {
      this._translucent = translucent;
      createRS = true;
    }

    if (defined(this._material)) {
      this._material.update(context);
    }

    var twoPasses = appearance.closed && translucent;

    if (createRS) {
      var rsFunc = defaultValue(
        this._createRenderStatesFunction,
        createRenderStates
      );
      rsFunc(this, context, appearance, twoPasses);
    }

    if (createSP) {
      var spFunc = defaultValue(
        this._createShaderProgramFunction,
        createShaderProgram
      );
      spFunc(this, frameState, appearance);
    }

    if (createRS || createSP) {
      var commandFunc = defaultValue(
        this._createCommandsFunction,
        createCommands
      );
      commandFunc(
        this,
        appearance,
        material,
        translucent,
        twoPasses,
        this._colorCommands,
        this._pickCommands,
        frameState
      );
    }

    var updateAndQueueCommandsFunc = defaultValue(
      this._updateAndQueueCommandsFunction,
      updateAndQueueCommands
    );
    updateAndQueueCommandsFunc(
      this,
      frameState,
      this._colorCommands,
      this._pickCommands,
      this.modelMatrix,
      this.cull,
      this.debugShowBoundingVolume,
      twoPasses
    );
  };

  var offsetBoundingSphereScratch1 = new BoundingSphere();
  var offsetBoundingSphereScratch2 = new BoundingSphere();
  function transformBoundingSphere(boundingSphere, offset, offsetAttribute) {
    if (offsetAttribute === GeometryOffsetAttribute$1.TOP) {
      var origBS = BoundingSphere.clone(
        boundingSphere,
        offsetBoundingSphereScratch1
      );
      var offsetBS = BoundingSphere.clone(
        boundingSphere,
        offsetBoundingSphereScratch2
      );
      offsetBS.center = Cartesian3.add(offsetBS.center, offset, offsetBS.center);
      boundingSphere = BoundingSphere.union(origBS, offsetBS, boundingSphere);
    } else if (offsetAttribute === GeometryOffsetAttribute$1.ALL) {
      boundingSphere.center = Cartesian3.add(
        boundingSphere.center,
        offset,
        boundingSphere.center
      );
    }

    return boundingSphere;
  }

  function createGetFunction(batchTable, instanceIndex, attributeIndex) {
    return function () {
      var attributeValue = batchTable.getBatchedAttribute(
        instanceIndex,
        attributeIndex
      );
      var attribute = batchTable.attributes[attributeIndex];
      var componentsPerAttribute = attribute.componentsPerAttribute;
      var value = ComponentDatatype$1.createTypedArray(
        attribute.componentDatatype,
        componentsPerAttribute
      );
      if (defined(attributeValue.constructor.pack)) {
        attributeValue.constructor.pack(attributeValue, value, 0);
      } else {
        value[0] = attributeValue;
      }
      return value;
    };
  }

  function createSetFunction(
    batchTable,
    instanceIndex,
    attributeIndex,
    primitive,
    name
  ) {
    return function (value) {
      //>>includeStart('debug', pragmas.debug);
      if (
        !defined(value) ||
        !defined(value.length) ||
        value.length < 1 ||
        value.length > 4
      ) {
        throw new DeveloperError(
          "value must be and array with length between 1 and 4."
        );
      }
      //>>includeEnd('debug');
      var attributeValue = getAttributeValue(value);
      batchTable.setBatchedAttribute(
        instanceIndex,
        attributeIndex,
        attributeValue
      );
      if (name === "offset") {
        primitive._recomputeBoundingSpheres = true;
        primitive._batchTableOffsetsUpdated = false;
      }
    };
  }

  var offsetScratch$2 = new Cartesian3();

  function createBoundingSphereProperties(primitive, properties, index) {
    properties.boundingSphere = {
      get: function () {
        var boundingSphere = primitive._instanceBoundingSpheres[index];
        if (defined(boundingSphere)) {
          boundingSphere = boundingSphere.clone();
          var modelMatrix = primitive.modelMatrix;
          var offset = properties.offset;
          if (defined(offset)) {
            transformBoundingSphere(
              boundingSphere,
              Cartesian3.fromArray(offset.get(), 0, offsetScratch$2),
              primitive._offsetInstanceExtend[index]
            );
          }
          if (defined(modelMatrix)) {
            boundingSphere = BoundingSphere.transform(
              boundingSphere,
              modelMatrix
            );
          }
        }

        return boundingSphere;
      },
    };
    properties.boundingSphereCV = {
      get: function () {
        return primitive._instanceBoundingSpheresCV[index];
      },
    };
  }

  function createPickIdProperty(primitive, properties, index) {
    properties.pickId = {
      get: function () {
        return primitive._pickIds[index];
      },
    };
  }

  /**
   * Returns the modifiable per-instance attributes for a {@link GeometryInstance}.
   *
   * @param {*} id The id of the {@link GeometryInstance}.
   * @returns {Object} The typed array in the attribute's format or undefined if the is no instance with id.
   *
   * @exception {DeveloperError} must call update before calling getGeometryInstanceAttributes.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA);
   * attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true);
   * attributes.distanceDisplayCondition = Cesium.DistanceDisplayConditionGeometryInstanceAttribute.toValue(100.0, 10000.0);
   * attributes.offset = Cesium.OffsetGeometryInstanceAttribute.toValue(Cartesian3.IDENTITY);
   */
  Primitive.prototype.getGeometryInstanceAttributes = function (id) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required");
    }
    if (!defined(this._batchTable)) {
      throw new DeveloperError(
        "must call update before calling getGeometryInstanceAttributes"
      );
    }
    //>>includeEnd('debug');

    var index = -1;
    var lastIndex = this._lastPerInstanceAttributeIndex;
    var ids = this._instanceIds;
    var length = ids.length;
    for (var i = 0; i < length; ++i) {
      var curIndex = (lastIndex + i) % length;
      if (id === ids[curIndex]) {
        index = curIndex;
        break;
      }
    }

    if (index === -1) {
      return undefined;
    }

    var attributes = this._perInstanceAttributeCache[index];
    if (defined(attributes)) {
      return attributes;
    }

    var batchTable = this._batchTable;
    var perInstanceAttributeIndices = this._batchTableAttributeIndices;
    attributes = {};
    var properties = {};

    for (var name in perInstanceAttributeIndices) {
      if (perInstanceAttributeIndices.hasOwnProperty(name)) {
        var attributeIndex = perInstanceAttributeIndices[name];
        properties[name] = {
          get: createGetFunction(batchTable, index, attributeIndex),
          set: createSetFunction(batchTable, index, attributeIndex, this, name),
        };
      }
    }

    createBoundingSphereProperties(this, properties, index);
    createPickIdProperty(this, properties, index);
    Object.defineProperties(attributes, properties);

    this._lastPerInstanceAttributeIndex = index;
    this._perInstanceAttributeCache[index] = attributes;
    return attributes;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Primitive#destroy
   */
  Primitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * e = e && e.destroy();
   *
   * @see Primitive#isDestroyed
   */
  Primitive.prototype.destroy = function () {
    var length;
    var i;

    this._sp = this._sp && this._sp.destroy();
    this._spDepthFail = this._spDepthFail && this._spDepthFail.destroy();

    var va = this._va;
    length = va.length;
    for (i = 0; i < length; ++i) {
      va[i].destroy();
    }
    this._va = undefined;

    var pickIds = this._pickIds;
    length = pickIds.length;
    for (i = 0; i < length; ++i) {
      pickIds[i].destroy();
    }
    this._pickIds = undefined;

    this._batchTable = this._batchTable && this._batchTable.destroy();

    //These objects may be fairly large and reference other large objects (like Entities)
    //We explicitly set them to undefined here so that the memory can be freed
    //even if a reference to the destroyed Primitive has been kept around.
    this._instanceIds = undefined;
    this._perInstanceAttributeCache = undefined;
    this._attributeLocations = undefined;

    return destroyObject(this);
  };

  function setReady(primitive, frameState, state, error) {
    primitive._error = error;
    primitive._state = state;
    frameState.afterRender.push(function () {
      primitive._ready =
        primitive._state === PrimitiveState$1.COMPLETE ||
        primitive._state === PrimitiveState$1.FAILED;
      if (!defined(error)) {
        primitive._readyPromise.resolve(primitive);
      } else {
        primitive._readyPromise.reject(error);
      }
    });
  }

  //This file is automatically rebuilt by the Cesium build process.
  var ShadowVolumeAppearanceFS = "#ifdef GL_EXT_frag_depth\n\
#extension GL_EXT_frag_depth : enable\n\
#endif\n\
#ifdef TEXTURE_COORDINATES\n\
#ifdef SPHERICAL\n\
varying vec4 v_sphericalExtents;\n\
#else // SPHERICAL\n\
varying vec2 v_inversePlaneExtents;\n\
varying vec4 v_westPlane;\n\
varying vec4 v_southPlane;\n\
#endif // SPHERICAL\n\
varying vec3 v_uvMinAndSphericalLongitudeRotation;\n\
varying vec3 v_uMaxAndInverseDistance;\n\
varying vec3 v_vMaxAndInverseDistance;\n\
#endif // TEXTURE_COORDINATES\n\
#ifdef PER_INSTANCE_COLOR\n\
varying vec4 v_color;\n\
#endif\n\
#ifdef NORMAL_EC\n\
vec3 getEyeCoordinate3FromWindowCoordinate(vec2 fragCoord, float logDepthOrDepth) {\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(fragCoord, logDepthOrDepth);\n\
return eyeCoordinate.xyz / eyeCoordinate.w;\n\
}\n\
vec3 vectorFromOffset(vec4 eyeCoordinate, vec2 positiveOffset) {\n\
vec2 glFragCoordXY = gl_FragCoord.xy;\n\
float upOrRightLogDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, (glFragCoordXY + positiveOffset) / czm_viewport.zw));\n\
float downOrLeftLogDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, (glFragCoordXY - positiveOffset) / czm_viewport.zw));\n\
bvec2 upOrRightInBounds = lessThan(glFragCoordXY + positiveOffset, czm_viewport.zw);\n\
float useUpOrRight = float(upOrRightLogDepth > 0.0 && upOrRightInBounds.x && upOrRightInBounds.y);\n\
float useDownOrLeft = float(useUpOrRight == 0.0);\n\
vec3 upOrRightEC = getEyeCoordinate3FromWindowCoordinate(glFragCoordXY + positiveOffset, upOrRightLogDepth);\n\
vec3 downOrLeftEC = getEyeCoordinate3FromWindowCoordinate(glFragCoordXY - positiveOffset, downOrLeftLogDepth);\n\
return (upOrRightEC - (eyeCoordinate.xyz / eyeCoordinate.w)) * useUpOrRight + ((eyeCoordinate.xyz / eyeCoordinate.w) - downOrLeftEC) * useDownOrLeft;\n\
}\n\
#endif // NORMAL_EC\n\
void main(void)\n\
{\n\
#ifdef REQUIRES_EC\n\
float logDepthOrDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, gl_FragCoord.xy / czm_viewport.zw));\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(gl_FragCoord.xy, logDepthOrDepth);\n\
#endif\n\
#ifdef REQUIRES_WC\n\
vec4 worldCoordinate4 = czm_inverseView * eyeCoordinate;\n\
vec3 worldCoordinate = worldCoordinate4.xyz / worldCoordinate4.w;\n\
#endif\n\
#ifdef TEXTURE_COORDINATES\n\
vec2 uv;\n\
#ifdef SPHERICAL\n\
vec2 sphericalLatLong = czm_approximateSphericalCoordinates(worldCoordinate);\n\
sphericalLatLong.y += v_uvMinAndSphericalLongitudeRotation.z;\n\
sphericalLatLong.y = czm_branchFreeTernary(sphericalLatLong.y < czm_pi, sphericalLatLong.y, sphericalLatLong.y - czm_twoPi);\n\
uv.x = (sphericalLatLong.y - v_sphericalExtents.y) * v_sphericalExtents.w;\n\
uv.y = (sphericalLatLong.x - v_sphericalExtents.x) * v_sphericalExtents.z;\n\
#else // SPHERICAL\n\
uv.x = czm_planeDistance(v_westPlane, eyeCoordinate.xyz / eyeCoordinate.w) * v_inversePlaneExtents.x;\n\
uv.y = czm_planeDistance(v_southPlane, eyeCoordinate.xyz / eyeCoordinate.w) * v_inversePlaneExtents.y;\n\
#endif // SPHERICAL\n\
#endif // TEXTURE_COORDINATES\n\
#ifdef PICK\n\
#ifdef CULL_FRAGMENTS\n\
if (0.0 <= uv.x && uv.x <= 1.0 && 0.0 <= uv.y && uv.y <= 1.0) {\n\
gl_FragColor.a = 1.0;\n\
czm_writeDepthClamp();\n\
}\n\
#else // CULL_FRAGMENTS\n\
gl_FragColor.a = 1.0;\n\
#endif // CULL_FRAGMENTS\n\
#else // PICK\n\
#ifdef CULL_FRAGMENTS\n\
if (uv.x <= 0.0 || 1.0 <= uv.x || uv.y <= 0.0 || 1.0 <= uv.y) {\n\
discard;\n\
}\n\
#endif\n\
#ifdef NORMAL_EC\n\
vec3 downUp = vectorFromOffset(eyeCoordinate, vec2(0.0, 1.0));\n\
vec3 leftRight = vectorFromOffset(eyeCoordinate, vec2(1.0, 0.0));\n\
vec3 normalEC = normalize(cross(leftRight, downUp));\n\
#endif\n\
#ifdef PER_INSTANCE_COLOR\n\
vec4 color = czm_gammaCorrect(v_color);\n\
#ifdef FLAT\n\
gl_FragColor = color;\n\
#else // FLAT\n\
czm_materialInput materialInput;\n\
materialInput.normalEC = normalEC;\n\
materialInput.positionToEyeEC = -eyeCoordinate.xyz;\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
material.diffuse = color.rgb;\n\
material.alpha = color.a;\n\
gl_FragColor = czm_phong(normalize(-eyeCoordinate.xyz), material, czm_lightDirectionEC);\n\
#endif // FLAT\n\
gl_FragColor.rgb *= gl_FragColor.a;\n\
#else // PER_INSTANCE_COLOR\n\
czm_materialInput materialInput;\n\
#ifdef USES_NORMAL_EC\n\
materialInput.normalEC = normalEC;\n\
#endif\n\
#ifdef USES_POSITION_TO_EYE_EC\n\
materialInput.positionToEyeEC = -eyeCoordinate.xyz;\n\
#endif\n\
#ifdef USES_TANGENT_TO_EYE\n\
materialInput.tangentToEyeMatrix = czm_eastNorthUpToEyeCoordinates(worldCoordinate, normalEC);\n\
#endif\n\
#ifdef USES_ST\n\
materialInput.st.x = czm_lineDistance(v_uvMinAndSphericalLongitudeRotation.xy, v_uMaxAndInverseDistance.xy, uv) * v_uMaxAndInverseDistance.z;\n\
materialInput.st.y = czm_lineDistance(v_uvMinAndSphericalLongitudeRotation.xy, v_vMaxAndInverseDistance.xy, uv) * v_vMaxAndInverseDistance.z;\n\
#endif\n\
czm_material material = czm_getMaterial(materialInput);\n\
#ifdef FLAT\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#else // FLAT\n\
gl_FragColor = czm_phong(normalize(-eyeCoordinate.xyz), material, czm_lightDirectionEC);\n\
#endif // FLAT\n\
gl_FragColor.rgb *= gl_FragColor.a;\n\
#endif // PER_INSTANCE_COLOR\n\
czm_writeDepthClamp();\n\
#endif // PICK\n\
}\n\
";

  /**
   * Creates shaders for a ClassificationPrimitive to use a given Appearance, as well as for picking.
   *
   * @param {Boolean} extentsCulling Discard fragments outside the instance's texture coordinate extents.
   * @param {Boolean} planarExtents If true, texture coordinates will be computed using planes instead of spherical coordinates.
   * @param {Appearance} appearance An Appearance to be used with a ClassificationPrimitive via GroundPrimitive.
   * @private
   */
  function ShadowVolumeAppearance(extentsCulling, planarExtents, appearance) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.bool("extentsCulling", extentsCulling);
    Check.typeOf.bool("planarExtents", planarExtents);
    Check.typeOf.object("appearance", appearance);
    //>>includeEnd('debug');

    this._projectionExtentDefines = {
      eastMostYhighDefine: "",
      eastMostYlowDefine: "",
      westMostYhighDefine: "",
      westMostYlowDefine: "",
    };

    // Compute shader dependencies
    var colorShaderDependencies = new ShaderDependencies();
    colorShaderDependencies.requiresTextureCoordinates = extentsCulling;
    colorShaderDependencies.requiresEC = !appearance.flat;

    var pickShaderDependencies = new ShaderDependencies();
    pickShaderDependencies.requiresTextureCoordinates = extentsCulling;

    if (appearance instanceof PerInstanceColorAppearance) {
      // PerInstanceColorAppearance doesn't have material.shaderSource, instead it has its own vertex and fragment shaders
      colorShaderDependencies.requiresNormalEC = !appearance.flat;
    } else {
      // Scan material source for what hookups are needed. Assume czm_materialInput materialInput.
      var materialShaderSource =
        appearance.material.shaderSource + "\n" + appearance.fragmentShaderSource;

      colorShaderDependencies.normalEC =
        materialShaderSource.indexOf("materialInput.normalEC") !== -1 ||
        materialShaderSource.indexOf("czm_getDefaultMaterial") !== -1;
      colorShaderDependencies.positionToEyeEC =
        materialShaderSource.indexOf("materialInput.positionToEyeEC") !== -1;
      colorShaderDependencies.tangentToEyeMatrix =
        materialShaderSource.indexOf("materialInput.tangentToEyeMatrix") !== -1;
      colorShaderDependencies.st =
        materialShaderSource.indexOf("materialInput.st") !== -1;
    }

    this._colorShaderDependencies = colorShaderDependencies;
    this._pickShaderDependencies = pickShaderDependencies;
    this._appearance = appearance;
    this._extentsCulling = extentsCulling;
    this._planarExtents = planarExtents;
  }

  /**
   * Create the fragment shader for a ClassificationPrimitive's color pass when rendering for color.
   *
   * @param {Boolean} columbusView2D Whether the shader will be used for Columbus View or 2D.
   * @returns {ShaderSource} Shader source for the fragment shader.
   */
  ShadowVolumeAppearance.prototype.createFragmentShader = function (
    columbusView2D
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.bool("columbusView2D", columbusView2D);
    //>>includeEnd('debug');

    var appearance = this._appearance;
    var dependencies = this._colorShaderDependencies;

    var defines = [];
    if (!columbusView2D && !this._planarExtents) {
      defines.push("SPHERICAL");
    }
    if (dependencies.requiresEC) {
      defines.push("REQUIRES_EC");
    }
    if (dependencies.requiresWC) {
      defines.push("REQUIRES_WC");
    }
    if (dependencies.requiresTextureCoordinates) {
      defines.push("TEXTURE_COORDINATES");
    }
    if (this._extentsCulling) {
      defines.push("CULL_FRAGMENTS");
    }
    if (dependencies.requiresNormalEC) {
      defines.push("NORMAL_EC");
    }
    if (appearance instanceof PerInstanceColorAppearance) {
      defines.push("PER_INSTANCE_COLOR");
    }

    // Material inputs. Use of parameters in the material is different
    // from requirement of the parameters in the overall shader, for example,
    // texture coordinates may be used for fragment culling but not for the material itself.
    if (dependencies.normalEC) {
      defines.push("USES_NORMAL_EC");
    }
    if (dependencies.positionToEyeEC) {
      defines.push("USES_POSITION_TO_EYE_EC");
    }
    if (dependencies.tangentToEyeMatrix) {
      defines.push("USES_TANGENT_TO_EYE");
    }
    if (dependencies.st) {
      defines.push("USES_ST");
    }

    if (appearance.flat) {
      defines.push("FLAT");
    }

    var materialSource = "";
    if (!(appearance instanceof PerInstanceColorAppearance)) {
      materialSource = appearance.material.shaderSource;
    }

    return new ShaderSource({
      defines: defines,
      sources: [materialSource, ShadowVolumeAppearanceFS],
    });
  };

  ShadowVolumeAppearance.prototype.createPickFragmentShader = function (
    columbusView2D
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.bool("columbusView2D", columbusView2D);
    //>>includeEnd('debug');

    var dependencies = this._pickShaderDependencies;

    var defines = ["PICK"];
    if (!columbusView2D && !this._planarExtents) {
      defines.push("SPHERICAL");
    }
    if (dependencies.requiresEC) {
      defines.push("REQUIRES_EC");
    }
    if (dependencies.requiresWC) {
      defines.push("REQUIRES_WC");
    }
    if (dependencies.requiresTextureCoordinates) {
      defines.push("TEXTURE_COORDINATES");
    }
    if (this._extentsCulling) {
      defines.push("CULL_FRAGMENTS");
    }
    return new ShaderSource({
      defines: defines,
      sources: [ShadowVolumeAppearanceFS],
      pickColorQualifier: "varying",
    });
  };

  /**
   * Create the vertex shader for a ClassificationPrimitive's color pass on the final of 3 shadow volume passes
   *
   * @param {String[]} defines External defines to pass to the vertex shader.
   * @param {String} vertexShaderSource ShadowVolumeAppearanceVS with any required modifications for computing position.
   * @param {Boolean} columbusView2D Whether the shader will be used for Columbus View or 2D.
   * @param {MapProjection} mapProjection Current scene's map projection.
   * @returns {String} Shader source for the vertex shader.
   */
  ShadowVolumeAppearance.prototype.createVertexShader = function (
    defines,
    vertexShaderSource,
    columbusView2D,
    mapProjection
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("defines", defines);
    Check.typeOf.string("vertexShaderSource", vertexShaderSource);
    Check.typeOf.bool("columbusView2D", columbusView2D);
    Check.defined("mapProjection", mapProjection);
    //>>includeEnd('debug');
    return createShadowVolumeAppearanceVS(
      this._colorShaderDependencies,
      this._planarExtents,
      columbusView2D,
      defines,
      vertexShaderSource,
      this._appearance,
      mapProjection,
      this._projectionExtentDefines
    );
  };

  /**
   * Create the vertex shader for a ClassificationPrimitive's pick pass on the final of 3 shadow volume passes
   *
   * @param {String[]} defines External defines to pass to the vertex shader.
   * @param {String} vertexShaderSource ShadowVolumeAppearanceVS with any required modifications for computing position and picking.
   * @param {Boolean} columbusView2D Whether the shader will be used for Columbus View or 2D.
   * @param {MapProjection} mapProjection Current scene's map projection.
   * @returns {String} Shader source for the vertex shader.
   */
  ShadowVolumeAppearance.prototype.createPickVertexShader = function (
    defines,
    vertexShaderSource,
    columbusView2D,
    mapProjection
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("defines", defines);
    Check.typeOf.string("vertexShaderSource", vertexShaderSource);
    Check.typeOf.bool("columbusView2D", columbusView2D);
    Check.defined("mapProjection", mapProjection);
    //>>includeEnd('debug');
    return createShadowVolumeAppearanceVS(
      this._pickShaderDependencies,
      this._planarExtents,
      columbusView2D,
      defines,
      vertexShaderSource,
      undefined,
      mapProjection,
      this._projectionExtentDefines
    );
  };

  var longitudeExtentsCartesianScratch = new Cartesian3();
  var longitudeExtentsCartographicScratch = new Cartographic();
  var longitudeExtentsEncodeScratch = {
    high: 0.0,
    low: 0.0,
  };
  function createShadowVolumeAppearanceVS(
    shaderDependencies,
    planarExtents,
    columbusView2D,
    defines,
    vertexShaderSource,
    appearance,
    mapProjection,
    projectionExtentDefines
  ) {
    var allDefines = defines.slice();

    if (projectionExtentDefines.eastMostYhighDefine === "") {
      var eastMostCartographic = longitudeExtentsCartographicScratch;
      eastMostCartographic.longitude = CesiumMath.PI;
      eastMostCartographic.latitude = 0.0;
      eastMostCartographic.height = 0.0;
      var eastMostCartesian = mapProjection.project(
        eastMostCartographic,
        longitudeExtentsCartesianScratch
      );
      var encoded = EncodedCartesian3.encode(
        eastMostCartesian.x,
        longitudeExtentsEncodeScratch
      );
      projectionExtentDefines.eastMostYhighDefine =
        "EAST_MOST_X_HIGH " +
        encoded.high.toFixed((encoded.high + "").length + 1);
      projectionExtentDefines.eastMostYlowDefine =
        "EAST_MOST_X_LOW " + encoded.low.toFixed((encoded.low + "").length + 1);

      var westMostCartographic = longitudeExtentsCartographicScratch;
      westMostCartographic.longitude = -CesiumMath.PI;
      westMostCartographic.latitude = 0.0;
      westMostCartographic.height = 0.0;
      var westMostCartesian = mapProjection.project(
        westMostCartographic,
        longitudeExtentsCartesianScratch
      );
      encoded = EncodedCartesian3.encode(
        westMostCartesian.x,
        longitudeExtentsEncodeScratch
      );
      projectionExtentDefines.westMostYhighDefine =
        "WEST_MOST_X_HIGH " +
        encoded.high.toFixed((encoded.high + "").length + 1);
      projectionExtentDefines.westMostYlowDefine =
        "WEST_MOST_X_LOW " + encoded.low.toFixed((encoded.low + "").length + 1);
    }

    if (columbusView2D) {
      allDefines.push(projectionExtentDefines.eastMostYhighDefine);
      allDefines.push(projectionExtentDefines.eastMostYlowDefine);
      allDefines.push(projectionExtentDefines.westMostYhighDefine);
      allDefines.push(projectionExtentDefines.westMostYlowDefine);
    }

    if (defined(appearance) && appearance instanceof PerInstanceColorAppearance) {
      allDefines.push("PER_INSTANCE_COLOR");
    }
    if (shaderDependencies.requiresTextureCoordinates) {
      allDefines.push("TEXTURE_COORDINATES");
      if (!(planarExtents || columbusView2D)) {
        allDefines.push("SPHERICAL");
      }
      if (columbusView2D) {
        allDefines.push("COLUMBUS_VIEW_2D");
      }
    }

    return new ShaderSource({
      defines: allDefines,
      sources: [vertexShaderSource],
    });
  }

  /**
   * Tracks shader dependencies.
   * @private
   */
  function ShaderDependencies() {
    this._requiresEC = false;
    this._requiresWC = false; // depends on eye coordinates, needed for material and for phong
    this._requiresNormalEC = false; // depends on eye coordinates, needed for material
    this._requiresTextureCoordinates = false; // depends on world coordinates, needed for material and for culling

    this._usesNormalEC = false;
    this._usesPositionToEyeEC = false;
    this._usesTangentToEyeMat = false;
    this._usesSt = false;
  }

  Object.defineProperties(ShaderDependencies.prototype, {
    // Set when assessing final shading (flat vs. phong) and culling using computed texture coordinates
    requiresEC: {
      get: function () {
        return this._requiresEC;
      },
      set: function (value) {
        this._requiresEC = value || this._requiresEC;
      },
    },
    requiresWC: {
      get: function () {
        return this._requiresWC;
      },
      set: function (value) {
        this._requiresWC = value || this._requiresWC;
        this.requiresEC = this._requiresWC;
      },
    },
    requiresNormalEC: {
      get: function () {
        return this._requiresNormalEC;
      },
      set: function (value) {
        this._requiresNormalEC = value || this._requiresNormalEC;
        this.requiresEC = this._requiresNormalEC;
      },
    },
    requiresTextureCoordinates: {
      get: function () {
        return this._requiresTextureCoordinates;
      },
      set: function (value) {
        this._requiresTextureCoordinates =
          value || this._requiresTextureCoordinates;
        this.requiresWC = this._requiresTextureCoordinates;
      },
    },
    // Get/Set when assessing material hookups
    normalEC: {
      set: function (value) {
        this.requiresNormalEC = value;
        this._usesNormalEC = value;
      },
      get: function () {
        return this._usesNormalEC;
      },
    },
    tangentToEyeMatrix: {
      set: function (value) {
        this.requiresWC = value;
        this.requiresNormalEC = value;
        this._usesTangentToEyeMat = value;
      },
      get: function () {
        return this._usesTangentToEyeMat;
      },
    },
    positionToEyeEC: {
      set: function (value) {
        this.requiresEC = value;
        this._usesPositionToEyeEC = value;
      },
      get: function () {
        return this._usesPositionToEyeEC;
      },
    },
    st: {
      set: function (value) {
        this.requiresTextureCoordinates = value;
        this._usesSt = value;
      },
      get: function () {
        return this._usesSt;
      },
    },
  });

  function pointLineDistance(point1, point2, point) {
    return (
      Math.abs(
        (point2.y - point1.y) * point.x -
          (point2.x - point1.x) * point.y +
          point2.x * point1.y -
          point2.y * point1.x
      ) / Cartesian2.distance(point2, point1)
    );
  }

  var points2DScratch$2 = [
    new Cartesian2(),
    new Cartesian2(),
    new Cartesian2(),
    new Cartesian2(),
  ];

  // textureCoordinateRotationPoints form 2 lines in the computed UV space that remap to desired texture coordinates.
  // This allows simulation of baked texture coordinates for EllipseGeometry, RectangleGeometry, and PolygonGeometry.
  function addTextureCoordinateRotationAttributes(
    attributes,
    textureCoordinateRotationPoints
  ) {
    var points2D = points2DScratch$2;

    var minXYCorner = Cartesian2.unpack(
      textureCoordinateRotationPoints,
      0,
      points2D[0]
    );
    var maxYCorner = Cartesian2.unpack(
      textureCoordinateRotationPoints,
      2,
      points2D[1]
    );
    var maxXCorner = Cartesian2.unpack(
      textureCoordinateRotationPoints,
      4,
      points2D[2]
    );

    attributes.uMaxVmax = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 4,
      normalize: false,
      value: [maxYCorner.x, maxYCorner.y, maxXCorner.x, maxXCorner.y],
    });

    var inverseExtentX =
      1.0 / pointLineDistance(minXYCorner, maxYCorner, maxXCorner);
    var inverseExtentY =
      1.0 / pointLineDistance(minXYCorner, maxXCorner, maxYCorner);

    attributes.uvMinAndExtents = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 4,
      normalize: false,
      value: [minXYCorner.x, minXYCorner.y, inverseExtentX, inverseExtentY],
    });
  }

  var cartographicScratch$1 = new Cartographic();
  var cornerScratch = new Cartesian3();
  var northWestScratch = new Cartesian3();
  var southEastScratch = new Cartesian3();
  var highLowScratch = { high: 0.0, low: 0.0 };
  function add2DTextureCoordinateAttributes(rectangle, projection, attributes) {
    // Compute corner positions in double precision
    var carto = cartographicScratch$1;
    carto.height = 0.0;

    carto.longitude = rectangle.west;
    carto.latitude = rectangle.south;

    var southWestCorner = projection.project(carto, cornerScratch);

    carto.latitude = rectangle.north;
    var northWest = projection.project(carto, northWestScratch);

    carto.longitude = rectangle.east;
    carto.latitude = rectangle.south;
    var southEast = projection.project(carto, southEastScratch);

    // Since these positions are all in the 2D plane, there's a lot of zeros
    // and a lot of repetition. So we only need to encode 4 values.
    // Encode:
    // x: x value for southWestCorner
    // y: y value for southWestCorner
    // z: y value for northWest
    // w: x value for southEast

    var valuesHigh = [0, 0, 0, 0];
    var valuesLow = [0, 0, 0, 0];
    var encoded = EncodedCartesian3.encode(southWestCorner.x, highLowScratch);
    valuesHigh[0] = encoded.high;
    valuesLow[0] = encoded.low;

    encoded = EncodedCartesian3.encode(southWestCorner.y, highLowScratch);
    valuesHigh[1] = encoded.high;
    valuesLow[1] = encoded.low;

    encoded = EncodedCartesian3.encode(northWest.y, highLowScratch);
    valuesHigh[2] = encoded.high;
    valuesLow[2] = encoded.low;

    encoded = EncodedCartesian3.encode(southEast.x, highLowScratch);
    valuesHigh[3] = encoded.high;
    valuesLow[3] = encoded.low;

    attributes.planes2D_HIGH = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 4,
      normalize: false,
      value: valuesHigh,
    });

    attributes.planes2D_LOW = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 4,
      normalize: false,
      value: valuesLow,
    });
  }

  var enuMatrixScratch = new Matrix4();
  var inverseEnuScratch = new Matrix4();
  var rectanglePointCartesianScratch = new Cartesian3();
  var rectangleCenterScratch$2 = new Cartographic();
  var pointsCartographicScratch = [
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
  ];
  /**
   * When computing planes to bound the rectangle,
   * need to factor in "bulge" and other distortion.
   * Flatten the ellipsoid-centered corners and edge-centers of the rectangle
   * into the plane of the local ENU system, compute bounds in 2D, and
   * project back to ellipsoid-centered.
   *
   * @private
   */
  function computeRectangleBounds(
    rectangle,
    ellipsoid,
    height,
    southWestCornerResult,
    eastVectorResult,
    northVectorResult
  ) {
    // Compute center of rectangle
    var centerCartographic = Rectangle.center(rectangle, rectangleCenterScratch$2);
    centerCartographic.height = height;
    var centerCartesian = Cartographic.toCartesian(
      centerCartographic,
      ellipsoid,
      rectanglePointCartesianScratch
    );
    var enuMatrix = Transforms.eastNorthUpToFixedFrame(
      centerCartesian,
      ellipsoid,
      enuMatrixScratch
    );
    var inverseEnu = Matrix4.inverse(enuMatrix, inverseEnuScratch);

    var west = rectangle.west;
    var east = rectangle.east;
    var north = rectangle.north;
    var south = rectangle.south;

    var cartographics = pointsCartographicScratch;
    cartographics[0].latitude = south;
    cartographics[0].longitude = west;
    cartographics[1].latitude = north;
    cartographics[1].longitude = west;
    cartographics[2].latitude = north;
    cartographics[2].longitude = east;
    cartographics[3].latitude = south;
    cartographics[3].longitude = east;

    var longitudeCenter = (west + east) * 0.5;
    var latitudeCenter = (north + south) * 0.5;

    cartographics[4].latitude = south;
    cartographics[4].longitude = longitudeCenter;
    cartographics[5].latitude = north;
    cartographics[5].longitude = longitudeCenter;
    cartographics[6].latitude = latitudeCenter;
    cartographics[6].longitude = west;
    cartographics[7].latitude = latitudeCenter;
    cartographics[7].longitude = east;

    var minX = Number.POSITIVE_INFINITY;
    var maxX = Number.NEGATIVE_INFINITY;
    var minY = Number.POSITIVE_INFINITY;
    var maxY = Number.NEGATIVE_INFINITY;
    for (var i = 0; i < 8; i++) {
      cartographics[i].height = height;
      var pointCartesian = Cartographic.toCartesian(
        cartographics[i],
        ellipsoid,
        rectanglePointCartesianScratch
      );
      Matrix4.multiplyByPoint(inverseEnu, pointCartesian, pointCartesian);
      pointCartesian.z = 0.0; // flatten into XY plane of ENU coordinate system
      minX = Math.min(minX, pointCartesian.x);
      maxX = Math.max(maxX, pointCartesian.x);
      minY = Math.min(minY, pointCartesian.y);
      maxY = Math.max(maxY, pointCartesian.y);
    }

    var southWestCorner = southWestCornerResult;
    southWestCorner.x = minX;
    southWestCorner.y = minY;
    southWestCorner.z = 0.0;
    Matrix4.multiplyByPoint(enuMatrix, southWestCorner, southWestCorner);

    var southEastCorner = eastVectorResult;
    southEastCorner.x = maxX;
    southEastCorner.y = minY;
    southEastCorner.z = 0.0;
    Matrix4.multiplyByPoint(enuMatrix, southEastCorner, southEastCorner);
    // make eastward vector
    Cartesian3.subtract(southEastCorner, southWestCorner, eastVectorResult);

    var northWestCorner = northVectorResult;
    northWestCorner.x = minX;
    northWestCorner.y = maxY;
    northWestCorner.z = 0.0;
    Matrix4.multiplyByPoint(enuMatrix, northWestCorner, northWestCorner);
    // make eastward vector
    Cartesian3.subtract(northWestCorner, southWestCorner, northVectorResult);
  }

  var eastwardScratch = new Cartesian3();
  var northwardScratch = new Cartesian3();
  var encodeScratch$1 = new EncodedCartesian3();
  /**
   * Gets an attributes object containing:
   * - 3 high-precision points as 6 GeometryInstanceAttributes. These points are used to compute eye-space planes.
   * - 1 texture coordinate rotation GeometryInstanceAttributes
   * - 2 GeometryInstanceAttributes used to compute high-precision points in 2D and Columbus View.
   *   These points are used to compute eye-space planes like above.
   *
   * Used to compute texture coordinates for small-area ClassificationPrimitives with materials or multiple non-overlapping instances.
   *
   * @see ShadowVolumeAppearance
   * @private
   *
   * @param {Rectangle} boundingRectangle Rectangle object that the points will approximately bound
   * @param {Number[]} textureCoordinateRotationPoints Points in the computed texture coordinate system for remapping texture coordinates
   * @param {Ellipsoid} ellipsoid Ellipsoid for converting Rectangle points to world coordinates
   * @param {MapProjection} projection The MapProjection used for 2D and Columbus View.
   * @param {Number} [height=0] The maximum height for the shadow volume.
   * @returns {Object} An attributes dictionary containing planar texture coordinate attributes.
   */
  ShadowVolumeAppearance.getPlanarTextureCoordinateAttributes = function (
    boundingRectangle,
    textureCoordinateRotationPoints,
    ellipsoid,
    projection,
    height
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("boundingRectangle", boundingRectangle);
    Check.defined(
      "textureCoordinateRotationPoints",
      textureCoordinateRotationPoints
    );
    Check.typeOf.object("ellipsoid", ellipsoid);
    Check.typeOf.object("projection", projection);
    //>>includeEnd('debug');

    var corner = cornerScratch;
    var eastward = eastwardScratch;
    var northward = northwardScratch;
    computeRectangleBounds(
      boundingRectangle,
      ellipsoid,
      defaultValue(height, 0.0),
      corner,
      eastward,
      northward
    );

    var attributes = {};
    addTextureCoordinateRotationAttributes(
      attributes,
      textureCoordinateRotationPoints
    );

    var encoded = EncodedCartesian3.fromCartesian(corner, encodeScratch$1);

    attributes.southWest_HIGH = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      normalize: false,
      value: Cartesian3.pack(encoded.high, [0, 0, 0]),
    });
    attributes.southWest_LOW = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      normalize: false,
      value: Cartesian3.pack(encoded.low, [0, 0, 0]),
    });
    attributes.eastward = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      normalize: false,
      value: Cartesian3.pack(eastward, [0, 0, 0]),
    });
    attributes.northward = new GeometryInstanceAttribute({
      componentDatatype: ComponentDatatype$1.FLOAT,
      componentsPerAttribute: 3,
      normalize: false,
      value: Cartesian3.pack(northward, [0, 0, 0]),
    });

    add2DTextureCoordinateAttributes(boundingRectangle, projection, attributes);
    return attributes;
  };

  var spherePointScratch = new Cartesian3();
  function latLongToSpherical(latitude, longitude, ellipsoid, result) {
    var cartographic = cartographicScratch$1;
    cartographic.latitude = latitude;
    cartographic.longitude = longitude;
    cartographic.height = 0.0;

    var spherePoint = Cartographic.toCartesian(
      cartographic,
      ellipsoid,
      spherePointScratch
    );

    // Project into plane with vertical for latitude
    var magXY = Math.sqrt(
      spherePoint.x * spherePoint.x + spherePoint.y * spherePoint.y
    );

    // Use fastApproximateAtan2 for alignment with shader
    var sphereLatitude = CesiumMath.fastApproximateAtan2(magXY, spherePoint.z);
    var sphereLongitude = CesiumMath.fastApproximateAtan2(
      spherePoint.x,
      spherePoint.y
    );

    result.x = sphereLatitude;
    result.y = sphereLongitude;

    return result;
  }

  var sphericalScratch = new Cartesian2();
  /**
   * Gets an attributes object containing:
   * - the southwest corner of a rectangular area in spherical coordinates, as well as the inverse of the latitude/longitude range.
   *   These are computed using the same atan2 approximation used in the shader.
   * - 1 texture coordinate rotation GeometryInstanceAttributes
   * - 2 GeometryInstanceAttributes used to compute high-precision points in 2D and Columbus View.
   *   These points are used to compute eye-space planes like above.
   *
   * Used when computing texture coordinates for large-area ClassificationPrimitives with materials or
   * multiple non-overlapping instances.
   * @see ShadowVolumeAppearance
   * @private
   *
   * @param {Rectangle} boundingRectangle Rectangle object that the spherical extents will approximately bound
   * @param {Number[]} textureCoordinateRotationPoints Points in the computed texture coordinate system for remapping texture coordinates
   * @param {Ellipsoid} ellipsoid Ellipsoid for converting Rectangle points to world coordinates
   * @param {MapProjection} projection The MapProjection used for 2D and Columbus View.
   * @returns {Object} An attributes dictionary containing spherical texture coordinate attributes.
   */
  ShadowVolumeAppearance.getSphericalExtentGeometryInstanceAttributes = function (
    boundingRectangle,
    textureCoordinateRotationPoints,
    ellipsoid,
    projection
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("boundingRectangle", boundingRectangle);
    Check.defined(
      "textureCoordinateRotationPoints",
      textureCoordinateRotationPoints
    );
    Check.typeOf.object("ellipsoid", ellipsoid);
    Check.typeOf.object("projection", projection);
    //>>includeEnd('debug');

    // rectangle cartographic coords !== spherical because it's on an ellipsoid
    var southWestExtents = latLongToSpherical(
      boundingRectangle.south,
      boundingRectangle.west,
      ellipsoid,
      sphericalScratch
    );

    var south = southWestExtents.x;
    var west = southWestExtents.y;

    var northEastExtents = latLongToSpherical(
      boundingRectangle.north,
      boundingRectangle.east,
      ellipsoid,
      sphericalScratch
    );
    var north = northEastExtents.x;
    var east = northEastExtents.y;

    // If the bounding rectangle crosses the IDL, rotate the spherical extents so the cross no longer happens.
    // This rotation must happen in the shader too.
    var rotationRadians = 0.0;
    if (west > east) {
      rotationRadians = CesiumMath.PI - west;
      west = -CesiumMath.PI;
      east += rotationRadians;
    }

    // Slightly pad extents to avoid floating point error when fragment culling at edges.
    south -= CesiumMath.EPSILON5;
    west -= CesiumMath.EPSILON5;
    north += CesiumMath.EPSILON5;
    east += CesiumMath.EPSILON5;

    var longitudeRangeInverse = 1.0 / (east - west);
    var latitudeRangeInverse = 1.0 / (north - south);

    var attributes = {
      sphericalExtents: new GeometryInstanceAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 4,
        normalize: false,
        value: [south, west, latitudeRangeInverse, longitudeRangeInverse],
      }),
      longitudeRotation: new GeometryInstanceAttribute({
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 1,
        normalize: false,
        value: [rotationRadians],
      }),
    };

    addTextureCoordinateRotationAttributes(
      attributes,
      textureCoordinateRotationPoints
    );
    add2DTextureCoordinateAttributes(boundingRectangle, projection, attributes);
    return attributes;
  };

  ShadowVolumeAppearance.hasAttributesForTextureCoordinatePlanes = function (
    attributes
  ) {
    return (
      defined(attributes.southWest_HIGH) &&
      defined(attributes.southWest_LOW) &&
      defined(attributes.northward) &&
      defined(attributes.eastward) &&
      defined(attributes.planes2D_HIGH) &&
      defined(attributes.planes2D_LOW) &&
      defined(attributes.uMaxVmax) &&
      defined(attributes.uvMinAndExtents)
    );
  };

  ShadowVolumeAppearance.hasAttributesForSphericalExtents = function (
    attributes
  ) {
    return (
      defined(attributes.sphericalExtents) &&
      defined(attributes.longitudeRotation) &&
      defined(attributes.planes2D_HIGH) &&
      defined(attributes.planes2D_LOW) &&
      defined(attributes.uMaxVmax) &&
      defined(attributes.uvMinAndExtents)
    );
  };

  function shouldUseSpherical(rectangle) {
    return (
      Math.max(rectangle.width, rectangle.height) >
      ShadowVolumeAppearance.MAX_WIDTH_FOR_PLANAR_EXTENTS
    );
  }

  /**
   * Computes whether the given rectangle is wide enough that texture coordinates
   * over its area should be computed using spherical extents instead of distance to planes.
   *
   * @param {Rectangle} rectangle A rectangle
   * @private
   */
  ShadowVolumeAppearance.shouldUseSphericalCoordinates = function (rectangle) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("rectangle", rectangle);
    //>>includeEnd('debug');

    return shouldUseSpherical(rectangle);
  };

  /**
   * Texture coordinates for ground primitives are computed either using spherical coordinates for large areas or
   * using distance from planes for small areas.
   *
   * @type {Number}
   * @constant
   * @private
   */
  ShadowVolumeAppearance.MAX_WIDTH_FOR_PLANAR_EXTENTS = CesiumMath.toRadians(1.0);

  /**
   * Determines the function used to compare stencil values for the stencil test.
   *
   * @enum {Number}
   */
  var StencilFunction = {
    /**
     * The stencil test never passes.
     *
     * @type {Number}
     * @constant
     */
    NEVER: WebGLConstants$1.NEVER,

    /**
     * The stencil test passes when the masked reference value is less than the masked stencil value.
     *
     * @type {Number}
     * @constant
     */
    LESS: WebGLConstants$1.LESS,

    /**
     * The stencil test passes when the masked reference value is equal to the masked stencil value.
     *
     * @type {Number}
     * @constant
     */
    EQUAL: WebGLConstants$1.EQUAL,

    /**
     * The stencil test passes when the masked reference value is less than or equal to the masked stencil value.
     *
     * @type {Number}
     * @constant
     */
    LESS_OR_EQUAL: WebGLConstants$1.LEQUAL,

    /**
     * The stencil test passes when the masked reference value is greater than the masked stencil value.
     *
     * @type {Number}
     * @constant
     */
    GREATER: WebGLConstants$1.GREATER,

    /**
     * The stencil test passes when the masked reference value is not equal to the masked stencil value.
     *
     * @type {Number}
     * @constant
     */
    NOT_EQUAL: WebGLConstants$1.NOTEQUAL,

    /**
     * The stencil test passes when the masked reference value is greater than or equal to the masked stencil value.
     *
     * @type {Number}
     * @constant
     */
    GREATER_OR_EQUAL: WebGLConstants$1.GEQUAL,

    /**
     * The stencil test always passes.
     *
     * @type {Number}
     * @constant
     */
    ALWAYS: WebGLConstants$1.ALWAYS,
  };
  var StencilFunction$1 = Object.freeze(StencilFunction);

  /**
   * Determines the action taken based on the result of the stencil test.
   *
   * @enum {Number}
   */
  var StencilOperation = {
    /**
     * Sets the stencil buffer value to zero.
     *
     * @type {Number}
     * @constant
     */
    ZERO: WebGLConstants$1.ZERO,

    /**
     * Does not change the stencil buffer.
     *
     * @type {Number}
     * @constant
     */
    KEEP: WebGLConstants$1.KEEP,

    /**
     * Replaces the stencil buffer value with the reference value.
     *
     * @type {Number}
     * @constant
     */
    REPLACE: WebGLConstants$1.REPLACE,

    /**
     * Increments the stencil buffer value, clamping to unsigned byte.
     *
     * @type {Number}
     * @constant
     */
    INCREMENT: WebGLConstants$1.INCR,

    /**
     * Decrements the stencil buffer value, clamping to zero.
     *
     * @type {Number}
     * @constant
     */
    DECREMENT: WebGLConstants$1.DECR,

    /**
     * Bitwise inverts the existing stencil buffer value.
     *
     * @type {Number}
     * @constant
     */
    INVERT: WebGLConstants$1.INVERT,

    /**
     * Increments the stencil buffer value, wrapping to zero when exceeding the unsigned byte range.
     *
     * @type {Number}
     * @constant
     */
    INCREMENT_WRAP: WebGLConstants$1.INCR_WRAP,

    /**
     * Decrements the stencil buffer value, wrapping to the maximum unsigned byte instead of going below zero.
     *
     * @type {Number}
     * @constant
     */
    DECREMENT_WRAP: WebGLConstants$1.DECR_WRAP,
  };
  var StencilOperation$1 = Object.freeze(StencilOperation);

  /**
   * The most significant bit is used to identify whether the pixel is 3D Tiles.
   * The next three bits store selection depth for the skip LODs optimization.
   * The last four bits are for increment/decrement shadow volume operations for classification.
   *
   * @private
   */
  var StencilConstants = {
    CESIUM_3D_TILE_MASK: 0x80,
    SKIP_LOD_MASK: 0x70,
    SKIP_LOD_BIT_SHIFT: 4,
    CLASSIFICATION_MASK: 0x0f,
  };

  StencilConstants.setCesium3DTileBit = function () {
    return {
      enabled: true,
      frontFunction: StencilFunction$1.ALWAYS,
      frontOperation: {
        fail: StencilOperation$1.KEEP,
        zFail: StencilOperation$1.KEEP,
        zPass: StencilOperation$1.REPLACE,
      },
      backFunction: StencilFunction$1.ALWAYS,
      backOperation: {
        fail: StencilOperation$1.KEEP,
        zFail: StencilOperation$1.KEEP,
        zPass: StencilOperation$1.REPLACE,
      },
      reference: StencilConstants.CESIUM_3D_TILE_MASK,
      mask: StencilConstants.CESIUM_3D_TILE_MASK,
    };
  };
  var StencilConstants$1 = Object.freeze(StencilConstants);

  /**
   * A classification primitive represents a volume enclosing geometry in the {@link Scene} to be highlighted.
   * <p>
   * A primitive combines geometry instances with an {@link Appearance} that describes the full shading, including
   * {@link Material} and {@link RenderState}.  Roughly, the geometry instance defines the structure and placement,
   * and the appearance defines the visual characteristics.  Decoupling geometry and appearance allows us to mix
   * and match most of them and add a new geometry or appearance independently of each other.
   * Only {@link PerInstanceColorAppearance} with the same color across all instances is supported at this time when using
   * ClassificationPrimitive directly.
   * For full {@link Appearance} support when classifying terrain or 3D Tiles use {@link GroundPrimitive} instead.
   * </p>
   * <p>
   * For correct rendering, this feature requires the EXT_frag_depth WebGL extension. For hardware that do not support this extension, there
   * will be rendering artifacts for some viewing angles.
   * </p>
   * <p>
   * Valid geometries are {@link BoxGeometry}, {@link CylinderGeometry}, {@link EllipsoidGeometry}, {@link PolylineVolumeGeometry}, and {@link SphereGeometry}.
   * </p>
   * <p>
   * Geometries that follow the surface of the ellipsoid, such as {@link CircleGeometry}, {@link CorridorGeometry}, {@link EllipseGeometry}, {@link PolygonGeometry}, and {@link RectangleGeometry},
   * are also valid if they are extruded volumes; otherwise, they will not be rendered.
   * </p>
   *
   * @alias ClassificationPrimitive
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Array|GeometryInstance} [options.geometryInstances] The geometry instances to render. This can either be a single instance or an array of length one.
   * @param {Appearance} [options.appearance] The appearance used to render the primitive. Defaults to PerInstanceColorAppearance when GeometryInstances have a color attribute.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Boolean} [options.vertexCacheOptimize=false] When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
   * @param {Boolean} [options.interleave=false] When <code>true</code>, geometry vertex attributes are interleaved, which can slightly improve rendering performance but increases load time.
   * @param {Boolean} [options.compressVertices=true] When <code>true</code>, the geometry vertices are compressed, which will save memory.
   * @param {Boolean} [options.releaseGeometryInstances=true] When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
   * @param {Boolean} [options.asynchronous=true] Determines if the primitive will be created asynchronously or block until ready. If false initializeTerrainHeights() must be called first.
   * @param {ClassificationType} [options.classificationType=ClassificationType.BOTH] Determines whether terrain, 3D Tiles or both will be classified.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {Boolean} [options.debugShowShadowVolume=false] For debugging only. Determines if the shadow volume for each geometry in the primitive is drawn. Must be <code>true</code> on
   *                  creation for the volumes to be created before the geometry is released or options.releaseGeometryInstance must be <code>false</code>.
   *
   * @see Primitive
   * @see GroundPrimitive
   * @see GeometryInstance
   * @see Appearance
   */
  function ClassificationPrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var geometryInstances = options.geometryInstances;

    /**
     * The geometry instance rendered with this primitive.  This may
     * be <code>undefined</code> if <code>options.releaseGeometryInstances</code>
     * is <code>true</code> when the primitive is constructed.
     * <p>
     * Changing this property after the primitive is rendered has no effect.
     * </p>
     * <p>
     * Because of the rendering technique used, all geometry instances must be the same color.
     * If there is an instance with a differing color, a <code>DeveloperError</code> will be thrown
     * on the first attempt to render.
     * </p>
     *
     * @readonly
     * @type {Array|GeometryInstance}
     *
     * @default undefined
     */
    this.geometryInstances = geometryInstances;
    /**
     * Determines if the primitive will be shown.  This affects all geometry
     * instances in the primitive.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.show = defaultValue(options.show, true);
    /**
     * Determines whether terrain, 3D Tiles or both will be classified.
     *
     * @type {ClassificationType}
     *
     * @default ClassificationType.BOTH
     */
    this.classificationType = defaultValue(
      options.classificationType,
      ClassificationType$1.BOTH
    );
    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );
    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the shadow volume for each geometry in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowShadowVolume = defaultValue(
      options.debugShowShadowVolume,
      false
    );
    this._debugShowShadowVolume = false;

    // These are used by GroundPrimitive to augment the shader and uniform map.
    this._extruded = defaultValue(options._extruded, false);
    this._uniformMap = options._uniformMap;

    this._sp = undefined;
    this._spStencil = undefined;
    this._spPick = undefined;
    this._spColor = undefined;

    this._spPick2D = undefined; // only derived if necessary
    this._spColor2D = undefined; // only derived if necessary

    this._rsStencilDepthPass = undefined;
    this._rsStencilDepthPass3DTiles = undefined;
    this._rsColorPass = undefined;
    this._rsPickPass = undefined;

    this._commandsIgnoreShow = [];

    this._ready = false;
    this._readyPromise = when.defer();

    this._primitive = undefined;
    this._pickPrimitive = options._pickPrimitive;

    // Set in update
    this._hasSphericalExtentsAttribute = false;
    this._hasPlanarExtentsAttributes = false;
    this._hasPerColorAttribute = false;

    this.appearance = options.appearance;

    this._createBoundingVolumeFunction = options._createBoundingVolumeFunction;
    this._updateAndQueueCommandsFunction =
      options._updateAndQueueCommandsFunction;

    this._usePickOffsets = false;

    this._primitiveOptions = {
      geometryInstances: undefined,
      appearance: undefined,
      vertexCacheOptimize: defaultValue(options.vertexCacheOptimize, false),
      interleave: defaultValue(options.interleave, false),
      releaseGeometryInstances: defaultValue(
        options.releaseGeometryInstances,
        true
      ),
      allowPicking: defaultValue(options.allowPicking, true),
      asynchronous: defaultValue(options.asynchronous, true),
      compressVertices: defaultValue(options.compressVertices, true),
      _createBoundingVolumeFunction: undefined,
      _createRenderStatesFunction: undefined,
      _createShaderProgramFunction: undefined,
      _createCommandsFunction: undefined,
      _updateAndQueueCommandsFunction: undefined,
      _createPickOffsets: true,
    };
  }

  Object.defineProperties(ClassificationPrimitive.prototype, {
    /**
     * When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    vertexCacheOptimize: {
      get: function () {
        return this._primitiveOptions.vertexCacheOptimize;
      },
    },

    /**
     * Determines if geometry vertex attributes are interleaved, which can slightly improve rendering performance.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    interleave: {
      get: function () {
        return this._primitiveOptions.interleave;
      },
    },

    /**
     * When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    releaseGeometryInstances: {
      get: function () {
        return this._primitiveOptions.releaseGeometryInstances;
      },
    },

    /**
     * When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    allowPicking: {
      get: function () {
        return this._primitiveOptions.allowPicking;
      },
    },

    /**
     * Determines if the geometry instances will be created and batched on a web worker.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    asynchronous: {
      get: function () {
        return this._primitiveOptions.asynchronous;
      },
    },

    /**
     * When <code>true</code>, geometry vertices are compressed, which will save memory.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    compressVertices: {
      get: function () {
        return this._primitiveOptions.compressVertices;
      },
    },

    /**
     * Determines if the primitive is complete and ready to render.  If this property is
     * true, the primitive will be rendered the next time that {@link ClassificationPrimitive#update}
     * is called.
     *
     * @memberof ClassificationPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof ClassificationPrimitive.prototype
     * @type {Promise.<ClassificationPrimitive>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Returns true if the ClassificationPrimitive needs a separate shader and commands for 2D.
     * This is because texture coordinates on ClassificationPrimitives are computed differently,
     * and are used for culling when multiple GeometryInstances are batched in one ClassificationPrimitive.
     * @memberof ClassificationPrimitive.prototype
     * @type {Boolean}
     * @readonly
     * @private
     */
    _needs2DShader: {
      get: function () {
        return (
          this._hasPlanarExtentsAttributes || this._hasSphericalExtentsAttribute
        );
      },
    },
  });

  /**
   * Determines if ClassificationPrimitive rendering is supported.
   *
   * @param {Scene} scene The scene.
   * @returns {Boolean} <code>true</code> if ClassificationPrimitives are supported; otherwise, returns <code>false</code>
   */
  ClassificationPrimitive.isSupported = function (scene) {
    return scene.context.stencilBuffer;
  };

  function getStencilDepthRenderState(enableStencil, mask3DTiles) {
    var stencilFunction = mask3DTiles
      ? StencilFunction$1.EQUAL
      : StencilFunction$1.ALWAYS;
    return {
      colorMask: {
        red: false,
        green: false,
        blue: false,
        alpha: false,
      },
      stencilTest: {
        enabled: enableStencil,
        frontFunction: stencilFunction,
        frontOperation: {
          fail: StencilOperation$1.KEEP,
          zFail: StencilOperation$1.DECREMENT_WRAP,
          zPass: StencilOperation$1.KEEP,
        },
        backFunction: stencilFunction,
        backOperation: {
          fail: StencilOperation$1.KEEP,
          zFail: StencilOperation$1.INCREMENT_WRAP,
          zPass: StencilOperation$1.KEEP,
        },
        reference: StencilConstants$1.CESIUM_3D_TILE_MASK,
        mask: StencilConstants$1.CESIUM_3D_TILE_MASK,
      },
      stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
      depthTest: {
        enabled: true,
        func: DepthFunction$1.LESS_OR_EQUAL,
      },
      depthMask: false,
    };
  }

  function getColorRenderState(enableStencil) {
    return {
      stencilTest: {
        enabled: enableStencil,
        frontFunction: StencilFunction$1.NOT_EQUAL,
        frontOperation: {
          fail: StencilOperation$1.ZERO,
          zFail: StencilOperation$1.ZERO,
          zPass: StencilOperation$1.ZERO,
        },
        backFunction: StencilFunction$1.NOT_EQUAL,
        backOperation: {
          fail: StencilOperation$1.ZERO,
          zFail: StencilOperation$1.ZERO,
          zPass: StencilOperation$1.ZERO,
        },
        reference: 0,
        mask: StencilConstants$1.CLASSIFICATION_MASK,
      },
      stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
      depthTest: {
        enabled: false,
      },
      depthMask: false,
      blending: BlendingState$1.PRE_MULTIPLIED_ALPHA_BLEND,
    };
  }

  var pickRenderState = {
    stencilTest: {
      enabled: true,
      frontFunction: StencilFunction$1.NOT_EQUAL,
      frontOperation: {
        fail: StencilOperation$1.ZERO,
        zFail: StencilOperation$1.ZERO,
        zPass: StencilOperation$1.ZERO,
      },
      backFunction: StencilFunction$1.NOT_EQUAL,
      backOperation: {
        fail: StencilOperation$1.ZERO,
        zFail: StencilOperation$1.ZERO,
        zPass: StencilOperation$1.ZERO,
      },
      reference: 0,
      mask: StencilConstants$1.CLASSIFICATION_MASK,
    },
    stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
    depthTest: {
      enabled: false,
    },
    depthMask: false,
  };

  function createRenderStates$1(
    classificationPrimitive,
    context,
    appearance,
    twoPasses
  ) {
    if (defined(classificationPrimitive._rsStencilDepthPass)) {
      return;
    }
    var stencilEnabled = !classificationPrimitive.debugShowShadowVolume;

    classificationPrimitive._rsStencilDepthPass = RenderState.fromCache(
      getStencilDepthRenderState(stencilEnabled, false)
    );
    classificationPrimitive._rsStencilDepthPass3DTiles = RenderState.fromCache(
      getStencilDepthRenderState(stencilEnabled, true)
    );
    classificationPrimitive._rsColorPass = RenderState.fromCache(
      getColorRenderState(stencilEnabled)
    );
    classificationPrimitive._rsPickPass = RenderState.fromCache(pickRenderState);
  }

  function modifyForEncodedNormals$1(primitive, vertexShaderSource) {
    if (!primitive.compressVertices) {
      return vertexShaderSource;
    }

    if (
      vertexShaderSource.search(/attribute\s+vec3\s+extrudeDirection;/g) !== -1
    ) {
      var attributeName = "compressedAttributes";

      //only shadow volumes use extrudeDirection, and shadow volumes use vertexFormat: POSITION_ONLY so we don't need to check other attributes
      var attributeDecl = "attribute vec2 " + attributeName + ";";

      var globalDecl = "vec3 extrudeDirection;\n";
      var decode =
        "    extrudeDirection = czm_octDecode(" + attributeName + ", 65535.0);\n";

      var modifiedVS = vertexShaderSource;
      modifiedVS = modifiedVS.replace(
        /attribute\s+vec3\s+extrudeDirection;/g,
        ""
      );
      modifiedVS = ShaderSource.replaceMain(
        modifiedVS,
        "czm_non_compressed_main"
      );
      var compressedMain =
        "void main() \n" +
        "{ \n" +
        decode +
        "    czm_non_compressed_main(); \n" +
        "}";

      return [attributeDecl, globalDecl, modifiedVS, compressedMain].join("\n");
    }
  }

  function createShaderProgram$1(classificationPrimitive, frameState) {
    var context = frameState.context;
    var primitive = classificationPrimitive._primitive;
    var vs = ShadowVolumeAppearanceVS;
    vs = classificationPrimitive._primitive._batchTable.getVertexShaderCallback()(
      vs
    );
    vs = Primitive._appendDistanceDisplayConditionToShader(primitive, vs);
    vs = Primitive._modifyShaderPosition(
      classificationPrimitive,
      vs,
      frameState.scene3DOnly
    );
    vs = Primitive._updateColorAttribute(primitive, vs);

    var planarExtents = classificationPrimitive._hasPlanarExtentsAttributes;
    var cullFragmentsUsingExtents =
      planarExtents || classificationPrimitive._hasSphericalExtentsAttribute;

    if (classificationPrimitive._extruded) {
      vs = modifyForEncodedNormals$1(primitive, vs);
    }

    var extrudedDefine = classificationPrimitive._extruded
      ? "EXTRUDED_GEOMETRY"
      : "";

    var vsSource = new ShaderSource({
      defines: [extrudedDefine],
      sources: [vs],
    });
    var fsSource = new ShaderSource({
      sources: [ShadowVolumeFS],
    });
    var attributeLocations =
      classificationPrimitive._primitive._attributeLocations;

    var shadowVolumeAppearance = new ShadowVolumeAppearance(
      cullFragmentsUsingExtents,
      planarExtents,
      classificationPrimitive.appearance
    );

    classificationPrimitive._spStencil = ShaderProgram.replaceCache({
      context: context,
      shaderProgram: classificationPrimitive._spStencil,
      vertexShaderSource: vsSource,
      fragmentShaderSource: fsSource,
      attributeLocations: attributeLocations,
    });

    if (classificationPrimitive._primitive.allowPicking) {
      var vsPick = ShaderSource.createPickVertexShaderSource(vs);
      vsPick = Primitive._appendShowToShader(primitive, vsPick);
      vsPick = Primitive._updatePickColorAttribute(vsPick);

      var pickFS3D = shadowVolumeAppearance.createPickFragmentShader(false);
      var pickVS3D = shadowVolumeAppearance.createPickVertexShader(
        [extrudedDefine],
        vsPick,
        false,
        frameState.mapProjection
      );

      classificationPrimitive._spPick = ShaderProgram.replaceCache({
        context: context,
        shaderProgram: classificationPrimitive._spPick,
        vertexShaderSource: pickVS3D,
        fragmentShaderSource: pickFS3D,
        attributeLocations: attributeLocations,
      });

      // Derive a 2D pick shader if the primitive uses texture coordinate-based fragment culling,
      // since texture coordinates are computed differently in 2D.
      if (cullFragmentsUsingExtents) {
        var pickProgram2D = context.shaderCache.getDerivedShaderProgram(
          classificationPrimitive._spPick,
          "2dPick"
        );
        if (!defined(pickProgram2D)) {
          var pickFS2D = shadowVolumeAppearance.createPickFragmentShader(true);
          var pickVS2D = shadowVolumeAppearance.createPickVertexShader(
            [extrudedDefine],
            vsPick,
            true,
            frameState.mapProjection
          );

          pickProgram2D = context.shaderCache.createDerivedShaderProgram(
            classificationPrimitive._spPick,
            "2dPick",
            {
              vertexShaderSource: pickVS2D,
              fragmentShaderSource: pickFS2D,
              attributeLocations: attributeLocations,
            }
          );
        }
        classificationPrimitive._spPick2D = pickProgram2D;
      }
    } else {
      classificationPrimitive._spPick = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: vsSource,
        fragmentShaderSource: fsSource,
        attributeLocations: attributeLocations,
      });
    }

    vs = Primitive._appendShowToShader(primitive, vs);
    vsSource = new ShaderSource({
      defines: [extrudedDefine],
      sources: [vs],
    });

    classificationPrimitive._sp = ShaderProgram.replaceCache({
      context: context,
      shaderProgram: classificationPrimitive._sp,
      vertexShaderSource: vsSource,
      fragmentShaderSource: fsSource,
      attributeLocations: attributeLocations,
    });

    // Create a fragment shader that computes only required material hookups using screen space techniques
    var fsColorSource = shadowVolumeAppearance.createFragmentShader(false);
    var vsColorSource = shadowVolumeAppearance.createVertexShader(
      [extrudedDefine],
      vs,
      false,
      frameState.mapProjection
    );

    classificationPrimitive._spColor = ShaderProgram.replaceCache({
      context: context,
      shaderProgram: classificationPrimitive._spColor,
      vertexShaderSource: vsColorSource,
      fragmentShaderSource: fsColorSource,
      attributeLocations: attributeLocations,
    });

    // Derive a 2D shader if the primitive uses texture coordinate-based fragment culling,
    // since texture coordinates are computed differently in 2D.
    // Any material that uses texture coordinates will also equip texture coordinate-based fragment culling.
    if (cullFragmentsUsingExtents) {
      var colorProgram2D = context.shaderCache.getDerivedShaderProgram(
        classificationPrimitive._spColor,
        "2dColor"
      );
      if (!defined(colorProgram2D)) {
        var fsColorSource2D = shadowVolumeAppearance.createFragmentShader(true);
        var vsColorSource2D = shadowVolumeAppearance.createVertexShader(
          [extrudedDefine],
          vs,
          true,
          frameState.mapProjection
        );

        colorProgram2D = context.shaderCache.createDerivedShaderProgram(
          classificationPrimitive._spColor,
          "2dColor",
          {
            vertexShaderSource: vsColorSource2D,
            fragmentShaderSource: fsColorSource2D,
            attributeLocations: attributeLocations,
          }
        );
      }
      classificationPrimitive._spColor2D = colorProgram2D;
    }
  }

  function createColorCommands(classificationPrimitive, colorCommands) {
    var primitive = classificationPrimitive._primitive;
    var length = primitive._va.length * 2; // each geometry (pack of vertex attributes) needs 2 commands: front/back stencils and fill
    colorCommands.length = length;

    var i;
    var command;
    var derivedCommand;
    var vaIndex = 0;
    var uniformMap = primitive._batchTable.getUniformMapCallback()(
      classificationPrimitive._uniformMap
    );

    var needs2DShader = classificationPrimitive._needs2DShader;

    for (i = 0; i < length; i += 2) {
      var vertexArray = primitive._va[vaIndex++];

      // Stencil depth command
      command = colorCommands[i];
      if (!defined(command)) {
        command = colorCommands[i] = new DrawCommand({
          owner: classificationPrimitive,
          primitiveType: primitive._primitiveType,
        });
      }

      command.vertexArray = vertexArray;
      command.renderState = classificationPrimitive._rsStencilDepthPass;
      command.shaderProgram = classificationPrimitive._sp;
      command.uniformMap = uniformMap;
      command.pass = Pass$1.TERRAIN_CLASSIFICATION;

      derivedCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.tileset
      );
      derivedCommand.renderState =
        classificationPrimitive._rsStencilDepthPass3DTiles;
      derivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      command.derivedCommands.tileset = derivedCommand;

      // Color command
      command = colorCommands[i + 1];
      if (!defined(command)) {
        command = colorCommands[i + 1] = new DrawCommand({
          owner: classificationPrimitive,
          primitiveType: primitive._primitiveType,
        });
      }

      command.vertexArray = vertexArray;
      command.renderState = classificationPrimitive._rsColorPass;
      command.shaderProgram = classificationPrimitive._spColor;
      command.pass = Pass$1.TERRAIN_CLASSIFICATION;

      var appearance = classificationPrimitive.appearance;
      var material = appearance.material;
      if (defined(material)) {
        uniformMap = combine(uniformMap, material._uniforms);
      }

      command.uniformMap = uniformMap;

      derivedCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.tileset
      );
      derivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      command.derivedCommands.tileset = derivedCommand;

      // Derive for 2D if texture coordinates are ever computed
      if (needs2DShader) {
        // First derive from the terrain command
        var derived2DCommand = DrawCommand.shallowClone(
          command,
          command.derivedCommands.appearance2D
        );
        derived2DCommand.shaderProgram = classificationPrimitive._spColor2D;
        command.derivedCommands.appearance2D = derived2DCommand;

        // Then derive from the 3D Tiles command
        derived2DCommand = DrawCommand.shallowClone(
          derivedCommand,
          derivedCommand.derivedCommands.appearance2D
        );
        derived2DCommand.shaderProgram = classificationPrimitive._spColor2D;
        derivedCommand.derivedCommands.appearance2D = derived2DCommand;
      }
    }

    var commandsIgnoreShow = classificationPrimitive._commandsIgnoreShow;
    var spStencil = classificationPrimitive._spStencil;

    var commandIndex = 0;
    length = commandsIgnoreShow.length = length / 2;

    for (var j = 0; j < length; ++j) {
      var commandIgnoreShow = (commandsIgnoreShow[j] = DrawCommand.shallowClone(
        colorCommands[commandIndex],
        commandsIgnoreShow[j]
      ));
      commandIgnoreShow.shaderProgram = spStencil;
      commandIgnoreShow.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW;

      commandIndex += 2;
    }
  }

  function createPickCommands(classificationPrimitive, pickCommands) {
    var usePickOffsets = classificationPrimitive._usePickOffsets;

    var primitive = classificationPrimitive._primitive;
    var length = primitive._va.length * 2; // each geometry (pack of vertex attributes) needs 2 commands: front/back stencils and fill

    // Fallback for batching same-color geometry instances
    var pickOffsets;
    var pickIndex = 0;
    var pickOffset;
    if (usePickOffsets) {
      pickOffsets = primitive._pickOffsets;
      length = pickOffsets.length * 2;
    }

    pickCommands.length = length;

    var j;
    var command;
    var derivedCommand;
    var vaIndex = 0;
    var uniformMap = primitive._batchTable.getUniformMapCallback()(
      classificationPrimitive._uniformMap
    );

    var needs2DShader = classificationPrimitive._needs2DShader;

    for (j = 0; j < length; j += 2) {
      var vertexArray = primitive._va[vaIndex++];
      if (usePickOffsets) {
        pickOffset = pickOffsets[pickIndex++];
        vertexArray = primitive._va[pickOffset.index];
      }

      // Stencil depth command
      command = pickCommands[j];
      if (!defined(command)) {
        command = pickCommands[j] = new DrawCommand({
          owner: classificationPrimitive,
          primitiveType: primitive._primitiveType,
          pickOnly: true,
        });
      }

      command.vertexArray = vertexArray;
      command.renderState = classificationPrimitive._rsStencilDepthPass;
      command.shaderProgram = classificationPrimitive._sp;
      command.uniformMap = uniformMap;
      command.pass = Pass$1.TERRAIN_CLASSIFICATION;
      if (usePickOffsets) {
        command.offset = pickOffset.offset;
        command.count = pickOffset.count;
      }

      // Derive for 3D Tiles classification
      derivedCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.tileset
      );
      derivedCommand.renderState =
        classificationPrimitive._rsStencilDepthPass3DTiles;
      derivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      command.derivedCommands.tileset = derivedCommand;

      // Pick color command
      command = pickCommands[j + 1];
      if (!defined(command)) {
        command = pickCommands[j + 1] = new DrawCommand({
          owner: classificationPrimitive,
          primitiveType: primitive._primitiveType,
          pickOnly: true,
        });
      }

      command.vertexArray = vertexArray;
      command.renderState = classificationPrimitive._rsPickPass;
      command.shaderProgram = classificationPrimitive._spPick;
      command.uniformMap = uniformMap;
      command.pass = Pass$1.TERRAIN_CLASSIFICATION;
      if (usePickOffsets) {
        command.offset = pickOffset.offset;
        command.count = pickOffset.count;
      }

      derivedCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.tileset
      );
      derivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      command.derivedCommands.tileset = derivedCommand;

      // Derive for 2D if texture coordinates are ever computed
      if (needs2DShader) {
        // First derive from the terrain command
        var derived2DCommand = DrawCommand.shallowClone(
          command,
          command.derivedCommands.pick2D
        );
        derived2DCommand.shaderProgram = classificationPrimitive._spPick2D;
        command.derivedCommands.pick2D = derived2DCommand;

        // Then derive from the 3D Tiles command
        derived2DCommand = DrawCommand.shallowClone(
          derivedCommand,
          derivedCommand.derivedCommands.pick2D
        );
        derived2DCommand.shaderProgram = classificationPrimitive._spPick2D;
        derivedCommand.derivedCommands.pick2D = derived2DCommand;
      }
    }
  }

  function createCommands$1(
    classificationPrimitive,
    appearance,
    material,
    translucent,
    twoPasses,
    colorCommands,
    pickCommands
  ) {
    createColorCommands(classificationPrimitive, colorCommands);
    createPickCommands(classificationPrimitive, pickCommands);
  }

  function boundingVolumeIndex(commandIndex, length) {
    return Math.floor((commandIndex % length) / 2);
  }

  function updateAndQueueRenderCommand(
    command,
    frameState,
    modelMatrix,
    cull,
    boundingVolume,
    debugShowBoundingVolume
  ) {
    command.modelMatrix = modelMatrix;
    command.boundingVolume = boundingVolume;
    command.cull = cull;
    command.debugShowBoundingVolume = debugShowBoundingVolume;

    frameState.commandList.push(command);
  }

  function updateAndQueuePickCommand(
    command,
    frameState,
    modelMatrix,
    cull,
    boundingVolume
  ) {
    command.modelMatrix = modelMatrix;
    command.boundingVolume = boundingVolume;
    command.cull = cull;

    frameState.commandList.push(command);
  }

  function updateAndQueueCommands$1(
    classificationPrimitive,
    frameState,
    colorCommands,
    pickCommands,
    modelMatrix,
    cull,
    debugShowBoundingVolume,
    twoPasses
  ) {
    var primitive = classificationPrimitive._primitive;
    Primitive._updateBoundingVolumes(primitive, frameState, modelMatrix);

    var boundingVolumes;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      boundingVolumes = primitive._boundingSphereWC;
    } else if (frameState.mode === SceneMode$1.COLUMBUS_VIEW) {
      boundingVolumes = primitive._boundingSphereCV;
    } else if (
      frameState.mode === SceneMode$1.SCENE2D &&
      defined(primitive._boundingSphere2D)
    ) {
      boundingVolumes = primitive._boundingSphere2D;
    } else if (defined(primitive._boundingSphereMorph)) {
      boundingVolumes = primitive._boundingSphereMorph;
    }

    var classificationType = classificationPrimitive.classificationType;
    var queueTerrainCommands =
      classificationType !== ClassificationType$1.CESIUM_3D_TILE;
    var queue3DTilesCommands = classificationType !== ClassificationType$1.TERRAIN;

    var passes = frameState.passes;

    var i;
    var boundingVolume;
    var command;

    if (passes.render) {
      var colorLength = colorCommands.length;
      for (i = 0; i < colorLength; ++i) {
        boundingVolume = boundingVolumes[boundingVolumeIndex(i, colorLength)];
        if (queueTerrainCommands) {
          command = colorCommands[i];
          updateAndQueueRenderCommand(
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
        if (queue3DTilesCommands) {
          command = colorCommands[i].derivedCommands.tileset;
          updateAndQueueRenderCommand(
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
      }

      if (frameState.invertClassification) {
        var ignoreShowCommands = classificationPrimitive._commandsIgnoreShow;
        var ignoreShowCommandsLength = ignoreShowCommands.length;
        for (i = 0; i < ignoreShowCommandsLength; ++i) {
          boundingVolume = boundingVolumes[i];
          command = ignoreShowCommands[i];
          updateAndQueueRenderCommand(
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
      }
    }

    if (passes.pick) {
      var pickLength = pickCommands.length;
      var pickOffsets = primitive._pickOffsets;
      for (i = 0; i < pickLength; ++i) {
        var pickOffset = pickOffsets[boundingVolumeIndex(i, pickLength)];
        boundingVolume = boundingVolumes[pickOffset.index];
        if (queueTerrainCommands) {
          command = pickCommands[i];
          updateAndQueuePickCommand(
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume
          );
        }
        if (queue3DTilesCommands) {
          command = pickCommands[i].derivedCommands.tileset;
          updateAndQueuePickCommand(
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume
          );
        }
      }
    }
  }

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} All instance geometries must have the same primitiveType.
   * @exception {DeveloperError} Appearance and material have a uniform with the same name.
   * @exception {DeveloperError} Not all of the geometry instances have the same color attribute.
   */
  ClassificationPrimitive.prototype.update = function (frameState) {
    if (!defined(this._primitive) && !defined(this.geometryInstances)) {
      return;
    }

    var appearance = this.appearance;
    if (defined(appearance) && defined(appearance.material)) {
      appearance.material.update(frameState.context);
    }

    var that = this;
    var primitiveOptions = this._primitiveOptions;

    if (!defined(this._primitive)) {
      var instances = Array.isArray(this.geometryInstances)
        ? this.geometryInstances
        : [this.geometryInstances];
      var length = instances.length;

      var i;
      var instance;
      var attributes;

      var hasPerColorAttribute = false;
      var allColorsSame = true;
      var firstColor;
      var hasSphericalExtentsAttribute = false;
      var hasPlanarExtentsAttributes = false;

      if (length > 0) {
        attributes = instances[0].attributes;
        // Not expecting these to be set by users, should only be set via GroundPrimitive.
        // So don't check for mismatch.
        hasSphericalExtentsAttribute = ShadowVolumeAppearance.hasAttributesForSphericalExtents(
          attributes
        );
        hasPlanarExtentsAttributes = ShadowVolumeAppearance.hasAttributesForTextureCoordinatePlanes(
          attributes
        );
        firstColor = attributes.color;
      }

      for (i = 0; i < length; i++) {
        instance = instances[i];
        var color = instance.attributes.color;
        if (defined(color)) {
          hasPerColorAttribute = true;
        }
        //>>includeStart('debug', pragmas.debug);
        else if (hasPerColorAttribute) {
          throw new DeveloperError(
            "All GeometryInstances must have color attributes to use per-instance color."
          );
        }
        //>>includeEnd('debug');

        allColorsSame =
          allColorsSame &&
          defined(color) &&
          ColorGeometryInstanceAttribute.equals(firstColor, color);
      }

      // If no attributes exist for computing spherical extents or fragment culling,
      // throw if the colors aren't all the same.
      if (
        !allColorsSame &&
        !hasSphericalExtentsAttribute &&
        !hasPlanarExtentsAttributes
      ) {
        throw new DeveloperError(
          "All GeometryInstances must have the same color attribute except via GroundPrimitives"
        );
      }

      // default to a color appearance
      if (hasPerColorAttribute && !defined(appearance)) {
        appearance = new PerInstanceColorAppearance({
          flat: true,
        });
        this.appearance = appearance;
      }

      //>>includeStart('debug', pragmas.debug);
      if (
        !hasPerColorAttribute &&
        appearance instanceof PerInstanceColorAppearance
      ) {
        throw new DeveloperError(
          "PerInstanceColorAppearance requires color GeometryInstanceAttributes on all GeometryInstances"
        );
      }
      if (
        defined(appearance.material) &&
        !hasSphericalExtentsAttribute &&
        !hasPlanarExtentsAttributes
      ) {
        throw new DeveloperError(
          "Materials on ClassificationPrimitives are not supported except via GroundPrimitives"
        );
      }
      //>>includeEnd('debug');

      this._usePickOffsets =
        !hasSphericalExtentsAttribute && !hasPlanarExtentsAttributes;
      this._hasSphericalExtentsAttribute = hasSphericalExtentsAttribute;
      this._hasPlanarExtentsAttributes = hasPlanarExtentsAttributes;
      this._hasPerColorAttribute = hasPerColorAttribute;

      var geometryInstances = new Array(length);
      for (i = 0; i < length; ++i) {
        instance = instances[i];
        geometryInstances[i] = new GeometryInstance({
          geometry: instance.geometry,
          attributes: instance.attributes,
          modelMatrix: instance.modelMatrix,
          id: instance.id,
          pickPrimitive: defaultValue(this._pickPrimitive, that),
        });
      }

      primitiveOptions.appearance = appearance;
      primitiveOptions.geometryInstances = geometryInstances;

      if (defined(this._createBoundingVolumeFunction)) {
        primitiveOptions._createBoundingVolumeFunction = function (
          frameState,
          geometry
        ) {
          that._createBoundingVolumeFunction(frameState, geometry);
        };
      }

      primitiveOptions._createRenderStatesFunction = function (
        primitive,
        context,
        appearance,
        twoPasses
      ) {
        createRenderStates$1(that);
      };
      primitiveOptions._createShaderProgramFunction = function (
        primitive,
        frameState,
        appearance
      ) {
        createShaderProgram$1(that, frameState);
      };
      primitiveOptions._createCommandsFunction = function (
        primitive,
        appearance,
        material,
        translucent,
        twoPasses,
        colorCommands,
        pickCommands
      ) {
        createCommands$1(
          that,
          undefined,
          undefined,
          true,
          false,
          colorCommands,
          pickCommands
        );
      };

      if (defined(this._updateAndQueueCommandsFunction)) {
        primitiveOptions._updateAndQueueCommandsFunction = function (
          primitive,
          frameState,
          colorCommands,
          pickCommands,
          modelMatrix,
          cull,
          debugShowBoundingVolume,
          twoPasses
        ) {
          that._updateAndQueueCommandsFunction(
            primitive,
            frameState,
            colorCommands,
            pickCommands,
            modelMatrix,
            cull,
            debugShowBoundingVolume,
            twoPasses
          );
        };
      } else {
        primitiveOptions._updateAndQueueCommandsFunction = function (
          primitive,
          frameState,
          colorCommands,
          pickCommands,
          modelMatrix,
          cull,
          debugShowBoundingVolume,
          twoPasses
        ) {
          updateAndQueueCommands$1(
            that,
            frameState,
            colorCommands,
            pickCommands,
            modelMatrix,
            cull,
            debugShowBoundingVolume);
        };
      }

      this._primitive = new Primitive(primitiveOptions);
      this._primitive.readyPromise.then(function (primitive) {
        that._ready = true;

        if (that.releaseGeometryInstances) {
          that.geometryInstances = undefined;
        }

        var error = primitive._error;
        if (!defined(error)) {
          that._readyPromise.resolve(that);
        } else {
          that._readyPromise.reject(error);
        }
      });
    }

    if (
      this.debugShowShadowVolume &&
      !this._debugShowShadowVolume &&
      this._ready
    ) {
      this._debugShowShadowVolume = true;
      this._rsStencilDepthPass = RenderState.fromCache(
        getStencilDepthRenderState(false, false)
      );
      this._rsStencilDepthPass3DTiles = RenderState.fromCache(
        getStencilDepthRenderState(false, true)
      );
      this._rsColorPass = RenderState.fromCache(getColorRenderState(false));
    } else if (!this.debugShowShadowVolume && this._debugShowShadowVolume) {
      this._debugShowShadowVolume = false;
      this._rsStencilDepthPass = RenderState.fromCache(
        getStencilDepthRenderState(true, false)
      );
      this._rsStencilDepthPass3DTiles = RenderState.fromCache(
        getStencilDepthRenderState(true, true)
      );
      this._rsColorPass = RenderState.fromCache(getColorRenderState(true));
    }
    // Update primitive appearance
    if (this._primitive.appearance !== appearance) {
      //>>includeStart('debug', pragmas.debug);
      // Check if the appearance is supported by the geometry attributes
      if (
        !this._hasSphericalExtentsAttribute &&
        !this._hasPlanarExtentsAttributes &&
        defined(appearance.material)
      ) {
        throw new DeveloperError(
          "Materials on ClassificationPrimitives are not supported except via GroundPrimitive"
        );
      }
      if (
        !this._hasPerColorAttribute &&
        appearance instanceof PerInstanceColorAppearance
      ) {
        throw new DeveloperError(
          "PerInstanceColorAppearance requires color GeometryInstanceAttribute"
        );
      }
      //>>includeEnd('debug');
      this._primitive.appearance = appearance;
    }

    this._primitive.show = this.show;
    this._primitive.debugShowBoundingVolume = this.debugShowBoundingVolume;
    this._primitive.update(frameState);
  };

  /**
   * Returns the modifiable per-instance attributes for a {@link GeometryInstance}.
   *
   * @param {*} id The id of the {@link GeometryInstance}.
   * @returns {Object} The typed array in the attribute's format or undefined if the is no instance with id.
   *
   * @exception {DeveloperError} must call update before calling getGeometryInstanceAttributes.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA);
   * attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true);
   */
  ClassificationPrimitive.prototype.getGeometryInstanceAttributes = function (
    id
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(this._primitive)) {
      throw new DeveloperError(
        "must call update before calling getGeometryInstanceAttributes"
      );
    }
    //>>includeEnd('debug');
    return this._primitive.getGeometryInstanceAttributes(id);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see ClassificationPrimitive#destroy
   */
  ClassificationPrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * e = e && e.destroy();
   *
   * @see ClassificationPrimitive#isDestroyed
   */
  ClassificationPrimitive.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    this._sp = this._sp && this._sp.destroy();
    this._spPick = this._spPick && this._spPick.destroy();
    this._spColor = this._spColor && this._spColor.destroy();

    // Derived programs, destroyed above if they existed.
    this._spPick2D = undefined;
    this._spColor2D = undefined;
    return destroyObject(this);
  };

  var GroundPrimitiveUniformMap = {
    u_globeMinimumAltitude: function () {
      return 55000.0;
    },
  };

  /**
   * A ground primitive represents geometry draped over terrain or 3D Tiles in the {@link Scene}.
   * <p>
   * A primitive combines geometry instances with an {@link Appearance} that describes the full shading, including
   * {@link Material} and {@link RenderState}.  Roughly, the geometry instance defines the structure and placement,
   * and the appearance defines the visual characteristics.  Decoupling geometry and appearance allows us to mix
   * and match most of them and add a new geometry or appearance independently of each other.
   * </p>
   * <p>
   * Support for the WEBGL_depth_texture extension is required to use GeometryInstances with different PerInstanceColors
   * or materials besides PerInstanceColorAppearance.
   * </p>
   * <p>
   * Textured GroundPrimitives were designed for notional patterns and are not meant for precisely mapping
   * textures to terrain - for that use case, use {@link SingleTileImageryProvider}.
   * </p>
   * <p>
   * For correct rendering, this feature requires the EXT_frag_depth WebGL extension. For hardware that do not support this extension, there
   * will be rendering artifacts for some viewing angles.
   * </p>
   * <p>
   * Valid geometries are {@link CircleGeometry}, {@link CorridorGeometry}, {@link EllipseGeometry}, {@link PolygonGeometry}, and {@link RectangleGeometry}.
   * </p>
   *
   * @alias GroundPrimitive
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Array|GeometryInstance} [options.geometryInstances] The geometry instances to render.
   * @param {Appearance} [options.appearance] The appearance used to render the primitive. Defaults to a flat PerInstanceColorAppearance when GeometryInstances have a color attribute.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Boolean} [options.vertexCacheOptimize=false] When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
   * @param {Boolean} [options.interleave=false] When <code>true</code>, geometry vertex attributes are interleaved, which can slightly improve rendering performance but increases load time.
   * @param {Boolean} [options.compressVertices=true] When <code>true</code>, the geometry vertices are compressed, which will save memory.
   * @param {Boolean} [options.releaseGeometryInstances=true] When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
   * @param {Boolean} [options.asynchronous=true] Determines if the primitive will be created asynchronously or block until ready. If false initializeTerrainHeights() must be called first.
   * @param {ClassificationType} [options.classificationType=ClassificationType.BOTH] Determines whether terrain, 3D Tiles or both will be classified.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {Boolean} [options.debugShowShadowVolume=false] For debugging only. Determines if the shadow volume for each geometry in the primitive is drawn. Must be <code>true</code> on
   *                  creation for the volumes to be created before the geometry is released or options.releaseGeometryInstance must be <code>false</code>.
   *
   * @example
   * // Example 1: Create primitive with a single instance
   * var rectangleInstance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.RectangleGeometry({
   *     rectangle : Cesium.Rectangle.fromDegrees(-140.0, 30.0, -100.0, 40.0)
   *   }),
   *   id : 'rectangle',
   *   attributes : {
   *     color : new Cesium.ColorGeometryInstanceAttribute(0.0, 1.0, 1.0, 0.5)
   *   }
   * });
   * scene.primitives.add(new Cesium.GroundPrimitive({
   *   geometryInstances : rectangleInstance
   * }));
   *
   * // Example 2: Batch instances
   * var color = new Cesium.ColorGeometryInstanceAttribute(0.0, 1.0, 1.0, 0.5); // Both instances must have the same color.
   * var rectangleInstance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.RectangleGeometry({
   *     rectangle : Cesium.Rectangle.fromDegrees(-140.0, 30.0, -100.0, 40.0)
   *   }),
   *   id : 'rectangle',
   *   attributes : {
   *     color : color
   *   }
   * });
   * var ellipseInstance = new Cesium.GeometryInstance({
   *     geometry : new Cesium.EllipseGeometry({
   *         center : Cesium.Cartesian3.fromDegrees(-105.0, 40.0),
   *         semiMinorAxis : 300000.0,
   *         semiMajorAxis : 400000.0
   *     }),
   *     id : 'ellipse',
   *     attributes : {
   *         color : color
   *     }
   * });
   * scene.primitives.add(new Cesium.GroundPrimitive({
   *   geometryInstances : [rectangleInstance, ellipseInstance]
   * }));
   *
   * @see Primitive
   * @see ClassificationPrimitive
   * @see GeometryInstance
   * @see Appearance
   */
  function GroundPrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var appearance = options.appearance;
    var geometryInstances = options.geometryInstances;
    if (!defined(appearance) && defined(geometryInstances)) {
      var geometryInstancesArray = Array.isArray(geometryInstances)
        ? geometryInstances
        : [geometryInstances];
      var geometryInstanceCount = geometryInstancesArray.length;
      for (var i = 0; i < geometryInstanceCount; i++) {
        var attributes = geometryInstancesArray[i].attributes;
        if (defined(attributes) && defined(attributes.color)) {
          appearance = new PerInstanceColorAppearance({
            flat: true,
          });
          break;
        }
      }
    }
    /**
     * The {@link Appearance} used to shade this primitive. Each geometry
     * instance is shaded with the same appearance.  Some appearances, like
     * {@link PerInstanceColorAppearance} allow giving each instance unique
     * properties.
     *
     * @type Appearance
     *
     * @default undefined
     */
    this.appearance = appearance;

    /**
     * The geometry instances rendered with this primitive.  This may
     * be <code>undefined</code> if <code>options.releaseGeometryInstances</code>
     * is <code>true</code> when the primitive is constructed.
     * <p>
     * Changing this property after the primitive is rendered has no effect.
     * </p>
     *
     * @readonly
     * @type {Array|GeometryInstance}
     *
     * @default undefined
     */
    this.geometryInstances = options.geometryInstances;
    /**
     * Determines if the primitive will be shown.  This affects all geometry
     * instances in the primitive.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.show = defaultValue(options.show, true);
    /**
     * Determines whether terrain, 3D Tiles or both will be classified.
     *
     * @type {ClassificationType}
     *
     * @default ClassificationType.BOTH
     */
    this.classificationType = defaultValue(
      options.classificationType,
      ClassificationType$1.BOTH
    );
    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the shadow volume for each geometry in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowShadowVolume = defaultValue(
      options.debugShowShadowVolume,
      false
    );

    this._boundingVolumes = [];
    this._boundingVolumes2D = [];

    this._ready = false;
    this._readyPromise = when.defer();

    this._primitive = undefined;

    this._maxHeight = undefined;
    this._minHeight = undefined;

    this._maxTerrainHeight = ApproximateTerrainHeights._defaultMaxTerrainHeight;
    this._minTerrainHeight = ApproximateTerrainHeights._defaultMinTerrainHeight;

    this._boundingSpheresKeys = [];
    this._boundingSpheres = [];

    this._useFragmentCulling = false;
    // Used when inserting in an OrderedPrimitiveCollection
    this._zIndex = undefined;

    var that = this;
    this._classificationPrimitiveOptions = {
      geometryInstances: undefined,
      appearance: undefined,
      vertexCacheOptimize: defaultValue(options.vertexCacheOptimize, false),
      interleave: defaultValue(options.interleave, false),
      releaseGeometryInstances: defaultValue(
        options.releaseGeometryInstances,
        true
      ),
      allowPicking: defaultValue(options.allowPicking, true),
      asynchronous: defaultValue(options.asynchronous, true),
      compressVertices: defaultValue(options.compressVertices, true),
      _createBoundingVolumeFunction: undefined,
      _updateAndQueueCommandsFunction: undefined,
      _pickPrimitive: that,
      _extruded: true,
      _uniformMap: GroundPrimitiveUniformMap,
    };
  }

  Object.defineProperties(GroundPrimitive.prototype, {
    /**
     * When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    vertexCacheOptimize: {
      get: function () {
        return this._classificationPrimitiveOptions.vertexCacheOptimize;
      },
    },

    /**
     * Determines if geometry vertex attributes are interleaved, which can slightly improve rendering performance.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    interleave: {
      get: function () {
        return this._classificationPrimitiveOptions.interleave;
      },
    },

    /**
     * When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    releaseGeometryInstances: {
      get: function () {
        return this._classificationPrimitiveOptions.releaseGeometryInstances;
      },
    },

    /**
     * When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    allowPicking: {
      get: function () {
        return this._classificationPrimitiveOptions.allowPicking;
      },
    },

    /**
     * Determines if the geometry instances will be created and batched on a web worker.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    asynchronous: {
      get: function () {
        return this._classificationPrimitiveOptions.asynchronous;
      },
    },

    /**
     * When <code>true</code>, geometry vertices are compressed, which will save memory.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    compressVertices: {
      get: function () {
        return this._classificationPrimitiveOptions.compressVertices;
      },
    },

    /**
     * Determines if the primitive is complete and ready to render.  If this property is
     * true, the primitive will be rendered the next time that {@link GroundPrimitive#update}
     * is called.
     *
     * @memberof GroundPrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof GroundPrimitive.prototype
     * @type {Promise.<GroundPrimitive>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  /**
   * Determines if GroundPrimitive rendering is supported.
   *
   * @function
   * @param {Scene} scene The scene.
   * @returns {Boolean} <code>true</code> if GroundPrimitives are supported; otherwise, returns <code>false</code>
   */
  GroundPrimitive.isSupported = ClassificationPrimitive.isSupported;

  function getComputeMaximumHeightFunction(primitive) {
    return function (granularity, ellipsoid) {
      var r = ellipsoid.maximumRadius;
      var delta = r / Math.cos(granularity * 0.5) - r;
      return primitive._maxHeight + delta;
    };
  }

  function getComputeMinimumHeightFunction(primitive) {
    return function (granularity, ellipsoid) {
      return primitive._minHeight;
    };
  }

  var scratchBVCartesianHigh = new Cartesian3();
  var scratchBVCartesianLow = new Cartesian3();
  var scratchBVCartesian = new Cartesian3();
  var scratchBVCartographic = new Cartographic();
  var scratchBVRectangle = new Rectangle();

  function getRectangle(frameState, geometry) {
    var ellipsoid = frameState.mapProjection.ellipsoid;

    if (
      !defined(geometry.attributes) ||
      !defined(geometry.attributes.position3DHigh)
    ) {
      if (defined(geometry.rectangle)) {
        return geometry.rectangle;
      }

      return undefined;
    }

    var highPositions = geometry.attributes.position3DHigh.values;
    var lowPositions = geometry.attributes.position3DLow.values;
    var length = highPositions.length;

    var minLat = Number.POSITIVE_INFINITY;
    var minLon = Number.POSITIVE_INFINITY;
    var maxLat = Number.NEGATIVE_INFINITY;
    var maxLon = Number.NEGATIVE_INFINITY;

    for (var i = 0; i < length; i += 3) {
      var highPosition = Cartesian3.unpack(
        highPositions,
        i,
        scratchBVCartesianHigh
      );
      var lowPosition = Cartesian3.unpack(lowPositions, i, scratchBVCartesianLow);

      var position = Cartesian3.add(
        highPosition,
        lowPosition,
        scratchBVCartesian
      );
      var cartographic = ellipsoid.cartesianToCartographic(
        position,
        scratchBVCartographic
      );

      var latitude = cartographic.latitude;
      var longitude = cartographic.longitude;

      minLat = Math.min(minLat, latitude);
      minLon = Math.min(minLon, longitude);
      maxLat = Math.max(maxLat, latitude);
      maxLon = Math.max(maxLon, longitude);
    }

    var rectangle = scratchBVRectangle;
    rectangle.north = maxLat;
    rectangle.south = minLat;
    rectangle.east = maxLon;
    rectangle.west = minLon;

    return rectangle;
  }

  function setMinMaxTerrainHeights(primitive, rectangle, ellipsoid) {
    var result = ApproximateTerrainHeights.getMinimumMaximumHeights(
      rectangle,
      ellipsoid
    );

    primitive._minTerrainHeight = result.minimumTerrainHeight;
    primitive._maxTerrainHeight = result.maximumTerrainHeight;
  }

  function createBoundingVolume(groundPrimitive, frameState, geometry) {
    var ellipsoid = frameState.mapProjection.ellipsoid;
    var rectangle = getRectangle(frameState, geometry);

    var obb = OrientedBoundingBox.fromRectangle(
      rectangle,
      groundPrimitive._minHeight,
      groundPrimitive._maxHeight,
      ellipsoid
    );
    groundPrimitive._boundingVolumes.push(obb);

    if (!frameState.scene3DOnly) {
      var projection = frameState.mapProjection;
      var boundingVolume = BoundingSphere.fromRectangleWithHeights2D(
        rectangle,
        projection,
        groundPrimitive._maxHeight,
        groundPrimitive._minHeight
      );
      Cartesian3.fromElements(
        boundingVolume.center.z,
        boundingVolume.center.x,
        boundingVolume.center.y,
        boundingVolume.center
      );

      groundPrimitive._boundingVolumes2D.push(boundingVolume);
    }
  }

  function boundingVolumeIndex$1(commandIndex, length) {
    return Math.floor((commandIndex % length) / 2);
  }

  function updateAndQueueRenderCommand$1(
    groundPrimitive,
    command,
    frameState,
    modelMatrix,
    cull,
    boundingVolume,
    debugShowBoundingVolume
  ) {
    // Use derived appearance command for 2D if needed
    var classificationPrimitive = groundPrimitive._primitive;
    if (
      frameState.mode !== SceneMode$1.SCENE3D &&
      command.shaderProgram === classificationPrimitive._spColor &&
      classificationPrimitive._needs2DShader
    ) {
      command = command.derivedCommands.appearance2D;
    }

    command.owner = groundPrimitive;
    command.modelMatrix = modelMatrix;
    command.boundingVolume = boundingVolume;
    command.cull = cull;
    command.debugShowBoundingVolume = debugShowBoundingVolume;

    frameState.commandList.push(command);
  }

  function updateAndQueuePickCommand$1(
    groundPrimitive,
    command,
    frameState,
    modelMatrix,
    cull,
    boundingVolume
  ) {
    // Use derived pick command for 2D if needed
    var classificationPrimitive = groundPrimitive._primitive;
    if (
      frameState.mode !== SceneMode$1.SCENE3D &&
      command.shaderProgram === classificationPrimitive._spPick &&
      classificationPrimitive._needs2DShader
    ) {
      command = command.derivedCommands.pick2D;
    }

    command.owner = groundPrimitive;
    command.modelMatrix = modelMatrix;
    command.boundingVolume = boundingVolume;
    command.cull = cull;

    frameState.commandList.push(command);
  }

  function updateAndQueueCommands$2(
    groundPrimitive,
    frameState,
    colorCommands,
    pickCommands,
    modelMatrix,
    cull,
    debugShowBoundingVolume,
    twoPasses
  ) {
    var boundingVolumes;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      boundingVolumes = groundPrimitive._boundingVolumes;
    } else {
      boundingVolumes = groundPrimitive._boundingVolumes2D;
    }

    var classificationType = groundPrimitive.classificationType;
    var queueTerrainCommands =
      classificationType !== ClassificationType$1.CESIUM_3D_TILE;
    var queue3DTilesCommands = classificationType !== ClassificationType$1.TERRAIN;

    var passes = frameState.passes;
    var classificationPrimitive = groundPrimitive._primitive;

    var i;
    var boundingVolume;
    var command;

    if (passes.render) {
      var colorLength = colorCommands.length;

      for (i = 0; i < colorLength; ++i) {
        boundingVolume = boundingVolumes[boundingVolumeIndex$1(i, colorLength)];
        if (queueTerrainCommands) {
          command = colorCommands[i];
          updateAndQueueRenderCommand$1(
            groundPrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
        if (queue3DTilesCommands) {
          command = colorCommands[i].derivedCommands.tileset;
          updateAndQueueRenderCommand$1(
            groundPrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
      }

      if (frameState.invertClassification) {
        var ignoreShowCommands = classificationPrimitive._commandsIgnoreShow;
        var ignoreShowCommandsLength = ignoreShowCommands.length;
        for (i = 0; i < ignoreShowCommandsLength; ++i) {
          boundingVolume = boundingVolumes[i];
          command = ignoreShowCommands[i];
          updateAndQueueRenderCommand$1(
            groundPrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
      }
    }

    if (passes.pick) {
      var pickLength = pickCommands.length;

      var pickOffsets;
      if (!groundPrimitive._useFragmentCulling) {
        // Must be using pick offsets
        pickOffsets = classificationPrimitive._primitive._pickOffsets;
      }
      for (i = 0; i < pickLength; ++i) {
        boundingVolume = boundingVolumes[boundingVolumeIndex$1(i, pickLength)];
        if (!groundPrimitive._useFragmentCulling) {
          var pickOffset = pickOffsets[boundingVolumeIndex$1(i, pickLength)];
          boundingVolume = boundingVolumes[pickOffset.index];
        }
        if (queueTerrainCommands) {
          command = pickCommands[i];
          updateAndQueuePickCommand$1(
            groundPrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume
          );
        }
        if (queue3DTilesCommands) {
          command = pickCommands[i].derivedCommands.tileset;
          updateAndQueuePickCommand$1(
            groundPrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume
          );
        }
      }
    }
  }

  /**
   * Initializes the minimum and maximum terrain heights. This only needs to be called if you are creating the
   * GroundPrimitive synchronously.
   *
   * @returns {Promise<void>} A promise that will resolve once the terrain heights have been loaded.
   *
   */
  GroundPrimitive.initializeTerrainHeights = function () {
    return ApproximateTerrainHeights.initialize();
  };

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} For synchronous GroundPrimitive, you must call GroundPrimitive.initializeTerrainHeights() and wait for the returned promise to resolve.
   * @exception {DeveloperError} All instance geometries must have the same primitiveType.
   * @exception {DeveloperError} Appearance and material have a uniform with the same name.
   */
  GroundPrimitive.prototype.update = function (frameState) {
    if (!defined(this._primitive) && !defined(this.geometryInstances)) {
      return;
    }

    if (!ApproximateTerrainHeights.initialized) {
      //>>includeStart('debug', pragmas.debug);
      if (!this.asynchronous) {
        throw new DeveloperError(
          "For synchronous GroundPrimitives, you must call GroundPrimitive.initializeTerrainHeights() and wait for the returned promise to resolve."
        );
      }
      //>>includeEnd('debug');

      GroundPrimitive.initializeTerrainHeights();
      return;
    }

    var that = this;
    var primitiveOptions = this._classificationPrimitiveOptions;

    if (!defined(this._primitive)) {
      var ellipsoid = frameState.mapProjection.ellipsoid;

      var instance;
      var geometry;
      var instanceType;

      var instances = Array.isArray(this.geometryInstances)
        ? this.geometryInstances
        : [this.geometryInstances];
      var length = instances.length;
      var groundInstances = new Array(length);

      var i;
      var rectangle;
      for (i = 0; i < length; ++i) {
        instance = instances[i];
        geometry = instance.geometry;
        var instanceRectangle = getRectangle(frameState, geometry);
        if (!defined(rectangle)) {
          rectangle = Rectangle.clone(instanceRectangle);
        } else if (defined(instanceRectangle)) {
          Rectangle.union(rectangle, instanceRectangle, rectangle);
        }

        var id = instance.id;
        if (defined(id) && defined(instanceRectangle)) {
          var boundingSphere = ApproximateTerrainHeights.getBoundingSphere(
            instanceRectangle,
            ellipsoid
          );
          this._boundingSpheresKeys.push(id);
          this._boundingSpheres.push(boundingSphere);
        }

        instanceType = geometry.constructor;
        if (!defined(instanceType) || !defined(instanceType.createShadowVolume)) {
          //>>includeStart('debug', pragmas.debug);
          throw new DeveloperError(
            "Not all of the geometry instances have GroundPrimitive support."
          );
          //>>includeEnd('debug');
        }
      }

      // Now compute the min/max heights for the primitive
      setMinMaxTerrainHeights(this, rectangle, ellipsoid);
      var exaggeration = frameState.terrainExaggeration;
      this._minHeight = this._minTerrainHeight * exaggeration;
      this._maxHeight = this._maxTerrainHeight * exaggeration;

      var useFragmentCulling = GroundPrimitive._supportsMaterials(
        frameState.context
      );
      this._useFragmentCulling = useFragmentCulling;

      if (useFragmentCulling) {
        // Determine whether to add spherical or planar extent attributes for computing texture coordinates.
        // This depends on the size of the GeometryInstances.
        var attributes;
        var usePlanarExtents = true;
        for (i = 0; i < length; ++i) {
          instance = instances[i];
          geometry = instance.geometry;
          rectangle = getRectangle(frameState, geometry);
          if (ShadowVolumeAppearance.shouldUseSphericalCoordinates(rectangle)) {
            usePlanarExtents = false;
            break;
          }
        }

        for (i = 0; i < length; ++i) {
          instance = instances[i];
          geometry = instance.geometry;
          instanceType = geometry.constructor;

          var boundingRectangle = getRectangle(frameState, geometry);
          var textureCoordinateRotationPoints =
            geometry.textureCoordinateRotationPoints;

          if (usePlanarExtents) {
            attributes = ShadowVolumeAppearance.getPlanarTextureCoordinateAttributes(
              boundingRectangle,
              textureCoordinateRotationPoints,
              ellipsoid,
              frameState.mapProjection,
              this._maxHeight
            );
          } else {
            attributes = ShadowVolumeAppearance.getSphericalExtentGeometryInstanceAttributes(
              boundingRectangle,
              textureCoordinateRotationPoints,
              ellipsoid,
              frameState.mapProjection
            );
          }

          var instanceAttributes = instance.attributes;
          for (var attributeKey in instanceAttributes) {
            if (instanceAttributes.hasOwnProperty(attributeKey)) {
              attributes[attributeKey] = instanceAttributes[attributeKey];
            }
          }

          groundInstances[i] = new GeometryInstance({
            geometry: instanceType.createShadowVolume(
              geometry,
              getComputeMinimumHeightFunction(this),
              getComputeMaximumHeightFunction(this)
            ),
            attributes: attributes,
            id: instance.id,
          });
        }
      } else {
        // ClassificationPrimitive will check if the colors are all the same if it detects lack of fragment culling attributes
        for (i = 0; i < length; ++i) {
          instance = instances[i];
          geometry = instance.geometry;
          instanceType = geometry.constructor;
          groundInstances[i] = new GeometryInstance({
            geometry: instanceType.createShadowVolume(
              geometry,
              getComputeMinimumHeightFunction(this),
              getComputeMaximumHeightFunction(this)
            ),
            attributes: instance.attributes,
            id: instance.id,
          });
        }
      }

      primitiveOptions.geometryInstances = groundInstances;
      primitiveOptions.appearance = this.appearance;

      primitiveOptions._createBoundingVolumeFunction = function (
        frameState,
        geometry
      ) {
        createBoundingVolume(that, frameState, geometry);
      };
      primitiveOptions._updateAndQueueCommandsFunction = function (
        primitive,
        frameState,
        colorCommands,
        pickCommands,
        modelMatrix,
        cull,
        debugShowBoundingVolume,
        twoPasses
      ) {
        updateAndQueueCommands$2(
          that,
          frameState,
          colorCommands,
          pickCommands,
          modelMatrix,
          cull,
          debugShowBoundingVolume);
      };

      this._primitive = new ClassificationPrimitive(primitiveOptions);
      this._primitive.readyPromise.then(function (primitive) {
        that._ready = true;

        if (that.releaseGeometryInstances) {
          that.geometryInstances = undefined;
        }

        var error = primitive._error;
        if (!defined(error)) {
          that._readyPromise.resolve(that);
        } else {
          that._readyPromise.reject(error);
        }
      });
    }

    this._primitive.appearance = this.appearance;
    this._primitive.show = this.show;
    this._primitive.debugShowShadowVolume = this.debugShowShadowVolume;
    this._primitive.debugShowBoundingVolume = this.debugShowBoundingVolume;
    this._primitive.update(frameState);
  };

  /**
   * @private
   */
  GroundPrimitive.prototype.getBoundingSphere = function (id) {
    var index = this._boundingSpheresKeys.indexOf(id);
    if (index !== -1) {
      return this._boundingSpheres[index];
    }

    return undefined;
  };

  /**
   * Returns the modifiable per-instance attributes for a {@link GeometryInstance}.
   *
   * @param {*} id The id of the {@link GeometryInstance}.
   * @returns {Object} The typed array in the attribute's format or undefined if the is no instance with id.
   *
   * @exception {DeveloperError} must call update before calling getGeometryInstanceAttributes.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA);
   * attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true);
   */
  GroundPrimitive.prototype.getGeometryInstanceAttributes = function (id) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(this._primitive)) {
      throw new DeveloperError(
        "must call update before calling getGeometryInstanceAttributes"
      );
    }
    //>>includeEnd('debug');
    return this._primitive.getGeometryInstanceAttributes(id);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see GroundPrimitive#destroy
   */
  GroundPrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * e = e && e.destroy();
   *
   * @see GroundPrimitive#isDestroyed
   */
  GroundPrimitive.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    return destroyObject(this);
  };

  /**
   * Exposed for testing.
   *
   * @param {Context} context Rendering context
   * @returns {Boolean} Whether or not the current context supports materials on GroundPrimitives.
   * @private
   */
  GroundPrimitive._supportsMaterials = function (context) {
    return context.depthTexture;
  };

  /**
   * Checks if the given Scene supports materials on GroundPrimitives.
   * Materials on GroundPrimitives require support for the WEBGL_depth_texture extension.
   *
   * @param {Scene} scene The current scene.
   * @returns {Boolean} Whether or not the current scene supports materials on GroundPrimitives.
   */
  GroundPrimitive.supportsMaterials = function (scene) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("scene", scene);
    //>>includeEnd('debug');

    return GroundPrimitive._supportsMaterials(scene.frameState.context);
  };

  /**
   * The interface for all {@link Property} objects that represent {@link Material} uniforms.
   * This type defines an interface and cannot be instantiated directly.
   *
   * @alias MaterialProperty
   * @constructor
   * @abstract
   *
   * @see ColorMaterialProperty
   * @see CompositeMaterialProperty
   * @see GridMaterialProperty
   * @see ImageMaterialProperty
   * @see PolylineGlowMaterialProperty
   * @see PolylineOutlineMaterialProperty
   * @see StripeMaterialProperty
   */
  function MaterialProperty() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(MaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof MaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof MaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Gets the {@link Material} type at the provided time.
   * @function
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  MaterialProperty.prototype.getType = DeveloperError.throwInstantiationError;

  /**
   * Gets the value of the property at the provided time.
   * @function
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  MaterialProperty.prototype.getValue = DeveloperError.throwInstantiationError;

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   * @function
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  MaterialProperty.prototype.equals = DeveloperError.throwInstantiationError;

  /**
   * @private
   */
  MaterialProperty.getValue = function (time, materialProperty, material) {
    var type;

    if (defined(materialProperty)) {
      type = materialProperty.getType(time);
      if (defined(type)) {
        if (!defined(material) || material.type !== type) {
          material = Material.fromType(type);
        }
        materialProperty.getValue(time, material.uniforms);
        return material;
      }
    }

    if (!defined(material) || material.type !== Material.ColorType) {
      material = Material.fromType(Material.ColorType);
    }
    Color.clone(Color.WHITE, material.uniforms.color);

    return material;
  };

  /**
   * Defines the interface for a dynamic geometry updater.  A DynamicGeometryUpdater
   * is responsible for handling visualization of a specific type of geometry
   * that needs to be recomputed based on simulation time.
   * This object is never used directly by client code, but is instead created by
   * {@link GeometryUpdater} implementations which contain dynamic geometry.
   *
   * This type defines an interface and cannot be instantiated directly.
   *
   * @alias DynamicGeometryUpdater
   * @constructor
   * @private
   * @abstract
   */
  function DynamicGeometryUpdater(
    geometryUpdater,
    primitives,
    orderedGroundPrimitives
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("geometryUpdater", geometryUpdater);
    Check.defined("primitives", primitives);
    Check.defined("orderedGroundPrimitives", orderedGroundPrimitives);
    //>>includeEnd('debug');

    this._primitives = primitives;
    this._orderedGroundPrimitives = orderedGroundPrimitives;
    this._primitive = undefined;
    this._outlinePrimitive = undefined;
    this._geometryUpdater = geometryUpdater;
    this._options = geometryUpdater._options;
    this._entity = geometryUpdater._entity;
    this._material = undefined;
  }

  DynamicGeometryUpdater.prototype._isHidden = function (entity, geometry, time) {
    return (
      !entity.isShowing ||
      !entity.isAvailable(time) ||
      !Property.getValueOrDefault(geometry.show, time, true)
    );
  };

  DynamicGeometryUpdater.prototype._setOptions =
    DeveloperError.throwInstantiationError;

  /**
   * Updates the geometry to the specified time.
   * @memberof DynamicGeometryUpdater
   * @function
   *
   * @param {JulianDate} time The current time.
   */
  DynamicGeometryUpdater.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var geometryUpdater = this._geometryUpdater;
    var onTerrain = geometryUpdater._onTerrain;

    var primitives = this._primitives;
    var orderedGroundPrimitives = this._orderedGroundPrimitives;
    if (onTerrain) {
      orderedGroundPrimitives.remove(this._primitive);
    } else {
      primitives.removeAndDestroy(this._primitive);
      primitives.removeAndDestroy(this._outlinePrimitive);
      this._outlinePrimitive = undefined;
    }
    this._primitive = undefined;

    var entity = this._entity;
    var geometry = entity[this._geometryUpdater._geometryPropertyName];
    this._setOptions(entity, geometry, time);
    if (this._isHidden(entity, geometry, time)) {
      return;
    }

    var shadows = this._geometryUpdater.shadowsProperty.getValue(time);
    var options = this._options;
    if (!defined(geometry.fill) || geometry.fill.getValue(time)) {
      var fillMaterialProperty = geometryUpdater.fillMaterialProperty;
      var isColorAppearance =
        fillMaterialProperty instanceof ColorMaterialProperty;
      var appearance;
      var closed = geometryUpdater._getIsClosed(options);
      if (isColorAppearance) {
        appearance = new PerInstanceColorAppearance({
          closed: closed,
          flat:
            onTerrain && !geometryUpdater._supportsMaterialsforEntitiesOnTerrain,
        });
      } else {
        var material = MaterialProperty.getValue(
          time,
          fillMaterialProperty,
          this._material
        );
        this._material = material;
        appearance = new MaterialAppearance({
          material: material,
          translucent: material.isTranslucent(),
          closed: closed,
        });
      }

      if (onTerrain) {
        options.vertexFormat = PerInstanceColorAppearance.VERTEX_FORMAT;
        this._primitive = orderedGroundPrimitives.add(
          new GroundPrimitive({
            geometryInstances: this._geometryUpdater.createFillGeometryInstance(
              time
            ),
            appearance: appearance,
            asynchronous: false,
            shadows: shadows,
            classificationType: this._geometryUpdater.classificationTypeProperty.getValue(
              time
            ),
          }),
          Property.getValueOrUndefined(this._geometryUpdater.zIndex, time)
        );
      } else {
        options.vertexFormat = appearance.vertexFormat;

        var fillInstance = this._geometryUpdater.createFillGeometryInstance(time);

        if (isColorAppearance) {
          appearance.translucent = fillInstance.attributes.color.value[3] !== 255;
        }

        this._primitive = primitives.add(
          new Primitive({
            geometryInstances: fillInstance,
            appearance: appearance,
            asynchronous: false,
            shadows: shadows,
          })
        );
      }
    }

    if (
      !onTerrain &&
      defined(geometry.outline) &&
      geometry.outline.getValue(time)
    ) {
      var outlineInstance = this._geometryUpdater.createOutlineGeometryInstance(
        time
      );
      var outlineWidth = Property.getValueOrDefault(
        geometry.outlineWidth,
        time,
        1.0
      );

      this._outlinePrimitive = primitives.add(
        new Primitive({
          geometryInstances: outlineInstance,
          appearance: new PerInstanceColorAppearance({
            flat: true,
            translucent: outlineInstance.attributes.color.value[3] !== 255,
            renderState: {
              lineWidth: geometryUpdater._scene.clampLineWidth(outlineWidth),
            },
          }),
          asynchronous: false,
          shadows: shadows,
        })
      );
    }
  };

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   * @function
   *
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  DynamicGeometryUpdater.prototype.getBoundingSphere = function (result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');
    var entity = this._entity;
    var primitive = this._primitive;
    var outlinePrimitive = this._outlinePrimitive;

    var attributes;

    //Outline and Fill geometries have the same bounding sphere, so just use whichever one is defined and ready
    if (defined(primitive) && primitive.show && primitive.ready) {
      attributes = primitive.getGeometryInstanceAttributes(entity);
      if (defined(attributes) && defined(attributes.boundingSphere)) {
        BoundingSphere.clone(attributes.boundingSphere, result);
        return BoundingSphereState$1.DONE;
      }
    }

    if (
      defined(outlinePrimitive) &&
      outlinePrimitive.show &&
      outlinePrimitive.ready
    ) {
      attributes = outlinePrimitive.getGeometryInstanceAttributes(entity);
      if (defined(attributes) && defined(attributes.boundingSphere)) {
        BoundingSphere.clone(attributes.boundingSphere, result);
        return BoundingSphereState$1.DONE;
      }
    }

    if (
      (defined(primitive) && !primitive.ready) ||
      (defined(outlinePrimitive) && !outlinePrimitive.ready)
    ) {
      return BoundingSphereState$1.PENDING;
    }

    return BoundingSphereState$1.FAILED;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * @memberof DynamicGeometryUpdater
   * @function
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  DynamicGeometryUpdater.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys and resources used by the object.  Once an object is destroyed, it should not be used.
   * @memberof DynamicGeometryUpdater
   * @function
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  DynamicGeometryUpdater.prototype.destroy = function () {
    var primitives = this._primitives;
    var orderedGroundPrimitives = this._orderedGroundPrimitives;
    if (this._geometryUpdater._onTerrain) {
      orderedGroundPrimitives.remove(this._primitive);
    } else {
      primitives.removeAndDestroy(this._primitive);
    }
    primitives.removeAndDestroy(this._outlinePrimitive);
    destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineShadowVolumeFS = "#ifdef GL_EXT_frag_depth\n\
#extension GL_EXT_frag_depth : enable\n\
#endif\n\
varying vec4 v_startPlaneNormalEcAndHalfWidth;\n\
varying vec4 v_endPlaneNormalEcAndBatchId;\n\
varying vec4 v_rightPlaneEC;\n\
varying vec4 v_endEcAndStartEcX;\n\
varying vec4 v_texcoordNormalizationAndStartEcYZ;\n\
#ifdef PER_INSTANCE_COLOR\n\
varying vec4 v_color;\n\
#endif\n\
void main(void)\n\
{\n\
float logDepthOrDepth = czm_branchFreeTernary(czm_sceneMode == czm_sceneMode2D, gl_FragCoord.z, czm_unpackDepth(texture2D(czm_globeDepthTexture, gl_FragCoord.xy / czm_viewport.zw)));\n\
vec3 ecStart = vec3(v_endEcAndStartEcX.w, v_texcoordNormalizationAndStartEcYZ.zw);\n\
if (logDepthOrDepth == 0.0) {\n\
#ifdef DEBUG_SHOW_VOLUME\n\
gl_FragColor = vec4(1.0, 0.0, 0.0, 0.5);\n\
return;\n\
#else // DEBUG_SHOW_VOLUME\n\
discard;\n\
#endif // DEBUG_SHOW_VOLUME\n\
}\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(gl_FragCoord.xy, logDepthOrDepth);\n\
eyeCoordinate /= eyeCoordinate.w;\n\
float halfMaxWidth = v_startPlaneNormalEcAndHalfWidth.w * czm_metersPerPixel(eyeCoordinate);\n\
float widthwiseDistance = czm_planeDistance(v_rightPlaneEC, eyeCoordinate.xyz);\n\
float distanceFromStart = czm_planeDistance(v_startPlaneNormalEcAndHalfWidth.xyz, -dot(ecStart, v_startPlaneNormalEcAndHalfWidth.xyz), eyeCoordinate.xyz);\n\
float distanceFromEnd = czm_planeDistance(v_endPlaneNormalEcAndBatchId.xyz, -dot(v_endEcAndStartEcX.xyz, v_endPlaneNormalEcAndBatchId.xyz), eyeCoordinate.xyz);\n\
if (abs(widthwiseDistance) > halfMaxWidth || distanceFromStart < 0.0 || distanceFromEnd < 0.0) {\n\
#ifdef DEBUG_SHOW_VOLUME\n\
gl_FragColor = vec4(1.0, 0.0, 0.0, 0.5);\n\
return;\n\
#else // DEBUG_SHOW_VOLUME\n\
discard;\n\
#endif // DEBUG_SHOW_VOLUME\n\
}\n\
vec3 alignedPlaneNormal;\n\
alignedPlaneNormal = cross(v_rightPlaneEC.xyz, v_startPlaneNormalEcAndHalfWidth.xyz);\n\
alignedPlaneNormal = normalize(cross(alignedPlaneNormal, v_rightPlaneEC.xyz));\n\
distanceFromStart = czm_planeDistance(alignedPlaneNormal, -dot(alignedPlaneNormal, ecStart), eyeCoordinate.xyz);\n\
alignedPlaneNormal = cross(v_rightPlaneEC.xyz, v_endPlaneNormalEcAndBatchId.xyz);\n\
alignedPlaneNormal = normalize(cross(alignedPlaneNormal, v_rightPlaneEC.xyz));\n\
distanceFromEnd = czm_planeDistance(alignedPlaneNormal, -dot(alignedPlaneNormal, v_endEcAndStartEcX.xyz), eyeCoordinate.xyz);\n\
#ifdef PER_INSTANCE_COLOR\n\
gl_FragColor = czm_gammaCorrect(v_color);\n\
#else // PER_INSTANCE_COLOR\n\
float s = clamp(distanceFromStart / (distanceFromStart + distanceFromEnd), 0.0, 1.0);\n\
s = (s * v_texcoordNormalizationAndStartEcYZ.x) + v_texcoordNormalizationAndStartEcYZ.y;\n\
float t = (widthwiseDistance + halfMaxWidth) / (2.0 * halfMaxWidth);\n\
czm_materialInput materialInput;\n\
materialInput.s = s;\n\
materialInput.st = vec2(s, t);\n\
materialInput.str = vec3(s, t, 0.0);\n\
czm_material material = czm_getMaterial(materialInput);\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#endif // PER_INSTANCE_COLOR\n\
gl_FragColor.rgb *= gl_FragColor.a;\n\
czm_writeDepthClamp();\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineShadowVolumeMorphFS = "varying vec3 v_forwardDirectionEC;\n\
varying vec3 v_texcoordNormalizationAndHalfWidth;\n\
varying float v_batchId;\n\
#ifdef PER_INSTANCE_COLOR\n\
varying vec4 v_color;\n\
#else\n\
varying vec2 v_alignedPlaneDistances;\n\
varying float v_texcoordT;\n\
#endif\n\
float rayPlaneDistanceUnsafe(vec3 origin, vec3 direction, vec3 planeNormal, float planeDistance) {\n\
return (-planeDistance - dot(planeNormal, origin)) / dot(planeNormal, direction);\n\
}\n\
void main(void)\n\
{\n\
vec4 eyeCoordinate = gl_FragCoord;\n\
eyeCoordinate /= eyeCoordinate.w;\n\
#ifdef PER_INSTANCE_COLOR\n\
gl_FragColor = czm_gammaCorrect(v_color);\n\
#else // PER_INSTANCE_COLOR\n\
float distanceFromStart = rayPlaneDistanceUnsafe(eyeCoordinate.xyz, -v_forwardDirectionEC, v_forwardDirectionEC.xyz, v_alignedPlaneDistances.x);\n\
float distanceFromEnd = rayPlaneDistanceUnsafe(eyeCoordinate.xyz, v_forwardDirectionEC, -v_forwardDirectionEC.xyz, v_alignedPlaneDistances.y);\n\
distanceFromStart = max(0.0, distanceFromStart);\n\
distanceFromEnd = max(0.0, distanceFromEnd);\n\
float s = distanceFromStart / (distanceFromStart + distanceFromEnd);\n\
s = (s * v_texcoordNormalizationAndHalfWidth.x) + v_texcoordNormalizationAndHalfWidth.y;\n\
czm_materialInput materialInput;\n\
materialInput.s = s;\n\
materialInput.st = vec2(s, v_texcoordT);\n\
materialInput.str = vec3(s, v_texcoordT, 0.0);\n\
czm_material material = czm_getMaterial(materialInput);\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#endif // PER_INSTANCE_COLOR\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineShadowVolumeMorphVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec4 startHiAndForwardOffsetX;\n\
attribute vec4 startLoAndForwardOffsetY;\n\
attribute vec4 startNormalAndForwardOffsetZ;\n\
attribute vec4 endNormalAndTextureCoordinateNormalizationX;\n\
attribute vec4 rightNormalAndTextureCoordinateNormalizationY;\n\
attribute vec4 startHiLo2D;\n\
attribute vec4 offsetAndRight2D;\n\
attribute vec4 startEndNormals2D;\n\
attribute vec2 texcoordNormalization2D;\n\
attribute float batchId;\n\
varying vec3 v_forwardDirectionEC;\n\
varying vec3 v_texcoordNormalizationAndHalfWidth;\n\
varying float v_batchId;\n\
#ifdef WIDTH_VARYING\n\
varying float v_width;\n\
#endif\n\
#ifdef ANGLE_VARYING\n\
varying float v_polylineAngle;\n\
#endif\n\
#ifdef PER_INSTANCE_COLOR\n\
varying vec4 v_color;\n\
#else\n\
varying vec2 v_alignedPlaneDistances;\n\
varying float v_texcoordT;\n\
#endif\n\
void main()\n\
{\n\
v_batchId = batchId;\n\
vec4 posRelativeToEye2D = czm_translateRelativeToEye(vec3(0.0, startHiLo2D.xy), vec3(0.0, startHiLo2D.zw));\n\
vec4 posRelativeToEye3D = czm_translateRelativeToEye(startHiAndForwardOffsetX.xyz, startLoAndForwardOffsetY.xyz);\n\
vec4 posRelativeToEye = czm_columbusViewMorph(posRelativeToEye2D, posRelativeToEye3D, czm_morphTime);\n\
vec3 posEc2D = (czm_modelViewRelativeToEye * posRelativeToEye2D).xyz;\n\
vec3 posEc3D = (czm_modelViewRelativeToEye * posRelativeToEye3D).xyz;\n\
vec3 startEC = (czm_modelViewRelativeToEye * posRelativeToEye).xyz;\n\
vec4 startPlane2D;\n\
vec4 startPlane3D;\n\
startPlane2D.xyz = czm_normal * vec3(0.0, startEndNormals2D.xy);\n\
startPlane3D.xyz = czm_normal * startNormalAndForwardOffsetZ.xyz;\n\
startPlane2D.w = -dot(startPlane2D.xyz, posEc2D);\n\
startPlane3D.w = -dot(startPlane3D.xyz, posEc3D);\n\
vec4 rightPlane2D;\n\
vec4 rightPlane3D;\n\
rightPlane2D.xyz = czm_normal * vec3(0.0, offsetAndRight2D.zw);\n\
rightPlane3D.xyz = czm_normal * rightNormalAndTextureCoordinateNormalizationY.xyz;\n\
rightPlane2D.w = -dot(rightPlane2D.xyz, posEc2D);\n\
rightPlane3D.w = -dot(rightPlane3D.xyz, posEc3D);\n\
posRelativeToEye2D = posRelativeToEye2D + vec4(0.0, offsetAndRight2D.xy, 0.0);\n\
posRelativeToEye3D = posRelativeToEye3D + vec4(startHiAndForwardOffsetX.w, startLoAndForwardOffsetY.w, startNormalAndForwardOffsetZ.w, 0.0);\n\
posRelativeToEye = czm_columbusViewMorph(posRelativeToEye2D, posRelativeToEye3D, czm_morphTime);\n\
posEc2D = (czm_modelViewRelativeToEye * posRelativeToEye2D).xyz;\n\
posEc3D = (czm_modelViewRelativeToEye * posRelativeToEye3D).xyz;\n\
vec3 endEC = (czm_modelViewRelativeToEye * posRelativeToEye).xyz;\n\
vec3 forwardEc3D = czm_normal * normalize(vec3(startHiAndForwardOffsetX.w, startLoAndForwardOffsetY.w, startNormalAndForwardOffsetZ.w));\n\
vec3 forwardEc2D = czm_normal * normalize(vec3(0.0, offsetAndRight2D.xy));\n\
vec4 endPlane2D;\n\
vec4 endPlane3D;\n\
endPlane2D.xyz = czm_normal * vec3(0.0, startEndNormals2D.zw);\n\
endPlane3D.xyz = czm_normal * endNormalAndTextureCoordinateNormalizationX.xyz;\n\
endPlane2D.w = -dot(endPlane2D.xyz, posEc2D);\n\
endPlane3D.w = -dot(endPlane3D.xyz, posEc3D);\n\
v_forwardDirectionEC = normalize(endEC - startEC);\n\
vec2 cleanTexcoordNormalization2D;\n\
cleanTexcoordNormalization2D.x = abs(texcoordNormalization2D.x);\n\
cleanTexcoordNormalization2D.y = czm_branchFreeTernary(texcoordNormalization2D.y > 1.0, 0.0, abs(texcoordNormalization2D.y));\n\
vec2 cleanTexcoordNormalization3D;\n\
cleanTexcoordNormalization3D.x = abs(endNormalAndTextureCoordinateNormalizationX.w);\n\
cleanTexcoordNormalization3D.y = rightNormalAndTextureCoordinateNormalizationY.w;\n\
cleanTexcoordNormalization3D.y = czm_branchFreeTernary(cleanTexcoordNormalization3D.y > 1.0, 0.0, abs(cleanTexcoordNormalization3D.y));\n\
v_texcoordNormalizationAndHalfWidth.xy = mix(cleanTexcoordNormalization2D, cleanTexcoordNormalization3D, czm_morphTime);\n\
#ifdef PER_INSTANCE_COLOR\n\
v_color = czm_batchTable_color(batchId);\n\
#else // PER_INSTANCE_COLOR\n\
v_alignedPlaneDistances.x = -dot(v_forwardDirectionEC, startEC);\n\
v_alignedPlaneDistances.y = -dot(-v_forwardDirectionEC, endEC);\n\
#endif // PER_INSTANCE_COLOR\n\
#ifdef WIDTH_VARYING\n\
float width = czm_batchTable_width(batchId);\n\
float halfWidth = width * 0.5;\n\
v_width = width;\n\
v_texcoordNormalizationAndHalfWidth.z = halfWidth;\n\
#else\n\
float halfWidth = 0.5 * czm_batchTable_width(batchId);\n\
v_texcoordNormalizationAndHalfWidth.z = halfWidth;\n\
#endif\n\
vec4 positionEc3D = czm_modelViewRelativeToEye * czm_translateRelativeToEye(position3DHigh, position3DLow);\n\
float absStartPlaneDistance = abs(czm_planeDistance(startPlane3D, positionEc3D.xyz));\n\
float absEndPlaneDistance = abs(czm_planeDistance(endPlane3D, positionEc3D.xyz));\n\
vec3 planeDirection = czm_branchFreeTernary(absStartPlaneDistance < absEndPlaneDistance, startPlane3D.xyz, endPlane3D.xyz);\n\
vec3 upOrDown = normalize(cross(rightPlane3D.xyz, planeDirection));\n\
vec3 normalEC = normalize(cross(planeDirection, upOrDown));\n\
vec3 geodeticSurfaceNormal = normalize(cross(normalEC, forwardEc3D));\n\
geodeticSurfaceNormal *= float(0.0 <= rightNormalAndTextureCoordinateNormalizationY.w && rightNormalAndTextureCoordinateNormalizationY.w <= 1.0);\n\
geodeticSurfaceNormal *= MAX_TERRAIN_HEIGHT;\n\
positionEc3D.xyz += geodeticSurfaceNormal;\n\
normalEC *= sign(endNormalAndTextureCoordinateNormalizationX.w);\n\
positionEc3D.xyz += halfWidth * max(0.0, czm_metersPerPixel(positionEc3D)) * normalEC;\n\
vec4 positionEc2D = czm_modelViewRelativeToEye * czm_translateRelativeToEye(position2DHigh.zxy, position2DLow.zxy);\n\
absStartPlaneDistance = abs(czm_planeDistance(startPlane2D, positionEc2D.xyz));\n\
absEndPlaneDistance = abs(czm_planeDistance(endPlane2D, positionEc2D.xyz));\n\
planeDirection = czm_branchFreeTernary(absStartPlaneDistance < absEndPlaneDistance, startPlane2D.xyz, endPlane2D.xyz);\n\
upOrDown = normalize(cross(rightPlane2D.xyz, planeDirection));\n\
normalEC = normalize(cross(planeDirection, upOrDown));\n\
geodeticSurfaceNormal = normalize(cross(normalEC, forwardEc2D));\n\
geodeticSurfaceNormal *= float(0.0 <= texcoordNormalization2D.y && texcoordNormalization2D.y <= 1.0);\n\
geodeticSurfaceNormal *= MAX_TERRAIN_HEIGHT;\n\
positionEc2D.xyz += geodeticSurfaceNormal;\n\
normalEC *= sign(texcoordNormalization2D.x);\n\
#ifndef PER_INSTANCE_COLOR\n\
v_texcoordT = clamp(sign(texcoordNormalization2D.x), 0.0, 1.0);\n\
#endif\n\
positionEc2D.xyz += halfWidth * max(0.0, czm_metersPerPixel(positionEc2D)) * normalEC;\n\
gl_Position = czm_projection * mix(positionEc2D, positionEc3D, czm_morphTime);\n\
#ifdef ANGLE_VARYING\n\
vec2 approxLineDirection = normalize(vec2(v_forwardDirectionEC.x, -v_forwardDirectionEC.y));\n\
approxLineDirection.y = czm_branchFreeTernary(approxLineDirection.x == 0.0 && approxLineDirection.y == 0.0, -1.0, approxLineDirection.y);\n\
v_polylineAngle = czm_fastApproximateAtan(approxLineDirection.x, approxLineDirection.y);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineShadowVolumeVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
#ifndef COLUMBUS_VIEW_2D\n\
attribute vec4 startHiAndForwardOffsetX;\n\
attribute vec4 startLoAndForwardOffsetY;\n\
attribute vec4 startNormalAndForwardOffsetZ;\n\
attribute vec4 endNormalAndTextureCoordinateNormalizationX;\n\
attribute vec4 rightNormalAndTextureCoordinateNormalizationY;\n\
#else\n\
attribute vec4 startHiLo2D;\n\
attribute vec4 offsetAndRight2D;\n\
attribute vec4 startEndNormals2D;\n\
attribute vec2 texcoordNormalization2D;\n\
#endif\n\
attribute float batchId;\n\
varying vec4 v_startPlaneNormalEcAndHalfWidth;\n\
varying vec4 v_endPlaneNormalEcAndBatchId;\n\
varying vec4 v_rightPlaneEC;\n\
varying vec4 v_endEcAndStartEcX;\n\
varying vec4 v_texcoordNormalizationAndStartEcYZ;\n\
#ifdef WIDTH_VARYING\n\
varying float v_width;\n\
#endif\n\
#ifdef ANGLE_VARYING\n\
varying float v_polylineAngle;\n\
#endif\n\
#ifdef PER_INSTANCE_COLOR\n\
varying vec4 v_color;\n\
#endif\n\
void main()\n\
{\n\
#ifdef COLUMBUS_VIEW_2D\n\
vec3 ecStart = (czm_modelViewRelativeToEye * czm_translateRelativeToEye(vec3(0.0, startHiLo2D.xy), vec3(0.0, startHiLo2D.zw))).xyz;\n\
vec3 forwardDirectionEC = czm_normal * vec3(0.0, offsetAndRight2D.xy);\n\
vec3 ecEnd = forwardDirectionEC + ecStart;\n\
forwardDirectionEC = normalize(forwardDirectionEC);\n\
v_rightPlaneEC.xyz = czm_normal * vec3(0.0, offsetAndRight2D.zw);\n\
v_rightPlaneEC.w = -dot(v_rightPlaneEC.xyz, ecStart);\n\
vec4 startPlaneEC;\n\
startPlaneEC.xyz =  czm_normal * vec3(0.0, startEndNormals2D.xy);\n\
startPlaneEC.w = -dot(startPlaneEC.xyz, ecStart);\n\
vec4 endPlaneEC;\n\
endPlaneEC.xyz =  czm_normal * vec3(0.0, startEndNormals2D.zw);\n\
endPlaneEC.w = -dot(endPlaneEC.xyz, ecEnd);\n\
v_texcoordNormalizationAndStartEcYZ.x = abs(texcoordNormalization2D.x);\n\
v_texcoordNormalizationAndStartEcYZ.y = texcoordNormalization2D.y;\n\
#else // COLUMBUS_VIEW_2D\n\
vec3 ecStart = (czm_modelViewRelativeToEye * czm_translateRelativeToEye(startHiAndForwardOffsetX.xyz, startLoAndForwardOffsetY.xyz)).xyz;\n\
vec3 offset = czm_normal * vec3(startHiAndForwardOffsetX.w, startLoAndForwardOffsetY.w, startNormalAndForwardOffsetZ.w);\n\
vec3 ecEnd = ecStart + offset;\n\
vec3 forwardDirectionEC = normalize(offset);\n\
vec4 startPlaneEC;\n\
startPlaneEC.xyz = czm_normal * startNormalAndForwardOffsetZ.xyz;\n\
startPlaneEC.w = -dot(startPlaneEC.xyz, ecStart);\n\
vec4 endPlaneEC;\n\
endPlaneEC.xyz = czm_normal * endNormalAndTextureCoordinateNormalizationX.xyz;\n\
endPlaneEC.w = -dot(endPlaneEC.xyz, ecEnd);\n\
v_rightPlaneEC.xyz = czm_normal * rightNormalAndTextureCoordinateNormalizationY.xyz;\n\
v_rightPlaneEC.w = -dot(v_rightPlaneEC.xyz, ecStart);\n\
v_texcoordNormalizationAndStartEcYZ.x = abs(endNormalAndTextureCoordinateNormalizationX.w);\n\
v_texcoordNormalizationAndStartEcYZ.y = rightNormalAndTextureCoordinateNormalizationY.w;\n\
#endif // COLUMBUS_VIEW_2D\n\
v_endEcAndStartEcX.xyz = ecEnd;\n\
v_endEcAndStartEcX.w = ecStart.x;\n\
v_texcoordNormalizationAndStartEcYZ.zw = ecStart.yz;\n\
#ifdef PER_INSTANCE_COLOR\n\
v_color = czm_batchTable_color(batchId);\n\
#endif // PER_INSTANCE_COLOR\n\
vec4 positionRelativeToEye = czm_computePosition();\n\
vec4 positionEC = czm_modelViewRelativeToEye * positionRelativeToEye;\n\
float absStartPlaneDistance = abs(czm_planeDistance(startPlaneEC, positionEC.xyz));\n\
float absEndPlaneDistance = abs(czm_planeDistance(endPlaneEC, positionEC.xyz));\n\
vec3 planeDirection = czm_branchFreeTernary(absStartPlaneDistance < absEndPlaneDistance, startPlaneEC.xyz, endPlaneEC.xyz);\n\
vec3 upOrDown = normalize(cross(v_rightPlaneEC.xyz, planeDirection));\n\
vec3 normalEC = normalize(cross(planeDirection, upOrDown));\n\
upOrDown = cross(forwardDirectionEC, normalEC);\n\
upOrDown = float(czm_sceneMode == czm_sceneMode3D) * upOrDown;\n\
upOrDown = float(v_texcoordNormalizationAndStartEcYZ.y > 1.0 || v_texcoordNormalizationAndStartEcYZ.y < 0.0) * upOrDown;\n\
upOrDown = min(GLOBE_MINIMUM_ALTITUDE, czm_geometricToleranceOverMeter * length(positionRelativeToEye.xyz)) * upOrDown;\n\
positionEC.xyz += upOrDown;\n\
v_texcoordNormalizationAndStartEcYZ.y = czm_branchFreeTernary(v_texcoordNormalizationAndStartEcYZ.y > 1.0, 0.0, abs(v_texcoordNormalizationAndStartEcYZ.y));\n\
float width = czm_batchTable_width(batchId);\n\
#ifdef WIDTH_VARYING\n\
v_width = width;\n\
#endif\n\
v_startPlaneNormalEcAndHalfWidth.xyz = startPlaneEC.xyz;\n\
v_startPlaneNormalEcAndHalfWidth.w = width * 0.5;\n\
v_endPlaneNormalEcAndBatchId.xyz = endPlaneEC.xyz;\n\
v_endPlaneNormalEcAndBatchId.w = batchId;\n\
width = width * max(0.0, czm_metersPerPixel(positionEC));\n\
width = width / dot(normalEC, v_rightPlaneEC.xyz);\n\
#ifdef COLUMBUS_VIEW_2D\n\
normalEC *= sign(texcoordNormalization2D.x);\n\
#else\n\
normalEC *= sign(endNormalAndTextureCoordinateNormalizationX.w);\n\
#endif\n\
positionEC.xyz += width * normalEC;\n\
gl_Position = czm_depthClamp(czm_projection * positionEC);\n\
#ifdef ANGLE_VARYING\n\
vec2 approxLineDirection = normalize(vec2(forwardDirectionEC.x, -forwardDirectionEC.y));\n\
approxLineDirection.y = czm_branchFreeTernary(approxLineDirection.x == 0.0 && approxLineDirection.y == 0.0, -1.0, approxLineDirection.y);\n\
v_polylineAngle = czm_fastApproximateAtan(approxLineDirection.x, approxLineDirection.y);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineColorAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 prevPosition3DHigh;\n\
attribute vec3 prevPosition3DLow;\n\
attribute vec3 nextPosition3DHigh;\n\
attribute vec3 nextPosition3DLow;\n\
attribute vec2 expandAndWidth;\n\
attribute vec4 color;\n\
attribute float batchId;\n\
varying vec4 v_color;\n\
void main()\n\
{\n\
float expandDir = expandAndWidth.x;\n\
float width = abs(expandAndWidth.y) + 0.5;\n\
bool usePrev = expandAndWidth.y < 0.0;\n\
vec4 p = czm_computePosition();\n\
vec4 prev = czm_computePrevPosition();\n\
vec4 next = czm_computeNextPosition();\n\
float angle;\n\
vec4 positionWC = getPolylineWindowCoordinates(p, prev, next, expandDir, width, usePrev, angle);\n\
gl_Position = czm_viewportOrthographic * positionWC;\n\
v_color = color;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineCommon = "void clipLineSegmentToNearPlane(\n\
vec3 p0,\n\
vec3 p1,\n\
out vec4 positionWC,\n\
out bool clipped,\n\
out bool culledByNearPlane,\n\
out vec4 clippedPositionEC)\n\
{\n\
culledByNearPlane = false;\n\
clipped = false;\n\
vec3 p0ToP1 = p1 - p0;\n\
float magnitude = length(p0ToP1);\n\
vec3 direction = normalize(p0ToP1);\n\
float endPoint0Distance =  czm_currentFrustum.x + p0.z;\n\
float denominator = -direction.z;\n\
if (endPoint0Distance > 0.0 && abs(denominator) < czm_epsilon7)\n\
{\n\
culledByNearPlane = true;\n\
}\n\
else if (endPoint0Distance > 0.0)\n\
{\n\
float t = endPoint0Distance / denominator;\n\
if (t < 0.0 || t > magnitude)\n\
{\n\
culledByNearPlane = true;\n\
}\n\
else\n\
{\n\
p0 = p0 + t * direction;\n\
p0.z = min(p0.z, -czm_currentFrustum.x);\n\
clipped = true;\n\
}\n\
}\n\
clippedPositionEC = vec4(p0, 1.0);\n\
positionWC = czm_eyeToWindowCoordinates(clippedPositionEC);\n\
}\n\
vec4 getPolylineWindowCoordinatesEC(vec4 positionEC, vec4 prevEC, vec4 nextEC, float expandDirection, float width, bool usePrevious, out float angle)\n\
{\n\
#ifdef POLYLINE_DASH\n\
vec4 positionWindow = czm_eyeToWindowCoordinates(positionEC);\n\
vec4 previousWindow = czm_eyeToWindowCoordinates(prevEC);\n\
vec4 nextWindow = czm_eyeToWindowCoordinates(nextEC);\n\
vec2 lineDir;\n\
if (usePrevious) {\n\
lineDir = normalize(positionWindow.xy - previousWindow.xy);\n\
}\n\
else {\n\
lineDir = normalize(nextWindow.xy - positionWindow.xy);\n\
}\n\
angle = atan(lineDir.x, lineDir.y) - 1.570796327;\n\
angle = floor(angle / czm_piOverFour + 0.5) * czm_piOverFour;\n\
#endif\n\
vec4 clippedPrevWC, clippedPrevEC;\n\
bool prevSegmentClipped, prevSegmentCulled;\n\
clipLineSegmentToNearPlane(prevEC.xyz, positionEC.xyz, clippedPrevWC, prevSegmentClipped, prevSegmentCulled, clippedPrevEC);\n\
vec4 clippedNextWC, clippedNextEC;\n\
bool nextSegmentClipped, nextSegmentCulled;\n\
clipLineSegmentToNearPlane(nextEC.xyz, positionEC.xyz, clippedNextWC, nextSegmentClipped, nextSegmentCulled, clippedNextEC);\n\
bool segmentClipped, segmentCulled;\n\
vec4 clippedPositionWC, clippedPositionEC;\n\
clipLineSegmentToNearPlane(positionEC.xyz, usePrevious ? prevEC.xyz : nextEC.xyz, clippedPositionWC, segmentClipped, segmentCulled, clippedPositionEC);\n\
if (segmentCulled)\n\
{\n\
return vec4(0.0, 0.0, 0.0, 1.0);\n\
}\n\
vec2 directionToPrevWC = normalize(clippedPrevWC.xy - clippedPositionWC.xy);\n\
vec2 directionToNextWC = normalize(clippedNextWC.xy - clippedPositionWC.xy);\n\
if (prevSegmentCulled)\n\
{\n\
directionToPrevWC = -directionToNextWC;\n\
}\n\
else if (nextSegmentCulled)\n\
{\n\
directionToNextWC = -directionToPrevWC;\n\
}\n\
vec2 thisSegmentForwardWC, otherSegmentForwardWC;\n\
if (usePrevious)\n\
{\n\
thisSegmentForwardWC = -directionToPrevWC;\n\
otherSegmentForwardWC = directionToNextWC;\n\
}\n\
else\n\
{\n\
thisSegmentForwardWC = directionToNextWC;\n\
otherSegmentForwardWC =  -directionToPrevWC;\n\
}\n\
vec2 thisSegmentLeftWC = vec2(-thisSegmentForwardWC.y, thisSegmentForwardWC.x);\n\
vec2 leftWC = thisSegmentLeftWC;\n\
float expandWidth = width * 0.5;\n\
if (!czm_equalsEpsilon(prevEC.xyz - positionEC.xyz, vec3(0.0), czm_epsilon1) && !czm_equalsEpsilon(nextEC.xyz - positionEC.xyz, vec3(0.0), czm_epsilon1))\n\
{\n\
vec2 otherSegmentLeftWC = vec2(-otherSegmentForwardWC.y, otherSegmentForwardWC.x);\n\
vec2 leftSumWC = thisSegmentLeftWC + otherSegmentLeftWC;\n\
float leftSumLength = length(leftSumWC);\n\
leftWC = leftSumLength < czm_epsilon6 ? thisSegmentLeftWC : (leftSumWC / leftSumLength);\n\
vec2 u = -thisSegmentForwardWC;\n\
vec2 v = leftWC;\n\
float sinAngle = abs(u.x * v.y - u.y * v.x);\n\
expandWidth = clamp(expandWidth / sinAngle, 0.0, width * 2.0);\n\
}\n\
vec2 offset = leftWC * expandDirection * expandWidth * czm_pixelRatio;\n\
return vec4(clippedPositionWC.xy + offset, -clippedPositionWC.z, 1.0) * (czm_projection * clippedPositionEC).w;\n\
}\n\
vec4 getPolylineWindowCoordinates(vec4 position, vec4 previous, vec4 next, float expandDirection, float width, bool usePrevious, out float angle)\n\
{\n\
vec4 positionEC = czm_modelViewRelativeToEye * position;\n\
vec4 prevEC = czm_modelViewRelativeToEye * previous;\n\
vec4 nextEC = czm_modelViewRelativeToEye * next;\n\
return getPolylineWindowCoordinatesEC(positionEC, prevEC, nextEC, expandDirection, width, usePrevious, angle);\n\
}\n\
";

  var defaultVertexShaderSource =
    PolylineCommon + "\n" + PolylineColorAppearanceVS;
  var defaultFragmentShaderSource = PerInstanceFlatColorAppearanceFS;

  if (!FeatureDetection.isInternetExplorer()) {
    defaultVertexShaderSource =
      "#define CLIP_POLYLINE \n" + defaultVertexShaderSource;
  }

  /**
   * An appearance for {@link GeometryInstance} instances with color attributes and
   * {@link PolylineGeometry} or {@link GroundPolylineGeometry}.
   * This allows several geometry instances, each with a different color, to
   * be drawn with the same {@link Primitive}.
   *
   * @alias PolylineColorAppearance
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.translucent=true] When <code>true</code>, the geometry is expected to appear translucent so {@link PolylineColorAppearance#renderState} has alpha blending enabled.
   * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
   * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
   * @param {Object} [options.renderState] Optional render state to override the default render state.
   *
   * @example
   * // A solid white line segment
   * var primitive = new Cesium.Primitive({
   *   geometryInstances : new Cesium.GeometryInstance({
   *     geometry : new Cesium.PolylineGeometry({
   *       positions : Cesium.Cartesian3.fromDegreesArray([
   *         0.0, 0.0,
   *         5.0, 0.0
   *       ]),
   *       width : 10.0,
   *       vertexFormat : Cesium.PolylineColorAppearance.VERTEX_FORMAT
   *     }),
   *     attributes : {
   *       color : Cesium.ColorGeometryInstanceAttribute.fromColor(new Cesium.Color(1.0, 1.0, 1.0, 1.0))
   *     }
   *   }),
   *   appearance : new Cesium.PolylineColorAppearance({
   *     translucent : false
   *   })
   * });
   */
  function PolylineColorAppearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var translucent = defaultValue(options.translucent, true);
    var closed = false;
    var vertexFormat = PolylineColorAppearance.VERTEX_FORMAT;

    /**
     * This property is part of the {@link Appearance} interface, but is not
     * used by {@link PolylineColorAppearance} since a fully custom fragment shader is used.
     *
     * @type Material
     *
     * @default undefined
     */
    this.material = undefined;

    /**
     * When <code>true</code>, the geometry is expected to appear translucent so
     * {@link PolylineColorAppearance#renderState} has alpha blending enabled.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.translucent = translucent;

    this._vertexShaderSource = defaultValue(
      options.vertexShaderSource,
      defaultVertexShaderSource
    );
    this._fragmentShaderSource = defaultValue(
      options.fragmentShaderSource,
      defaultFragmentShaderSource
    );
    this._renderState = Appearance.getDefaultRenderState(
      translucent,
      closed,
      options.renderState
    );
    this._closed = closed;

    // Non-derived members

    this._vertexFormat = vertexFormat;
  }

  Object.defineProperties(PolylineColorAppearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof PolylineColorAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },

    /**
     * The GLSL source code for the fragment shader.
     *
     * @memberof PolylineColorAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     * <p>
     * The render state can be explicitly defined when constructing a {@link PolylineColorAppearance}
     * instance, or it is set implicitly via {@link PolylineColorAppearance#translucent}.
     * </p>
     *
     * @memberof PolylineColorAppearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed so
     * {@link PolylineColorAppearance#renderState} has backface culling enabled.
     * This is always <code>false</code> for <code>PolylineColorAppearance</code>.
     *
     * @memberof PolylineColorAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },

    /**
     * The {@link VertexFormat} that this appearance instance is compatible with.
     * A geometry can have more vertex attributes and still be compatible - at a
     * potential performance cost - but it can't have less.
     *
     * @memberof PolylineColorAppearance.prototype
     *
     * @type VertexFormat
     * @readonly
     *
     * @default {@link PolylineColorAppearance.VERTEX_FORMAT}
     */
    vertexFormat: {
      get: function () {
        return this._vertexFormat;
      },
    },
  });

  /**
   * The {@link VertexFormat} that all {@link PolylineColorAppearance} instances
   * are compatible with. This requires only a <code>position</code> attribute.
   *
   * @type VertexFormat
   *
   * @constant
   */
  PolylineColorAppearance.VERTEX_FORMAT = VertexFormat.POSITION_ONLY;

  /**
   * Procedurally creates the full GLSL fragment shader source.
   *
   * @function
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  PolylineColorAppearance.prototype.getFragmentShaderSource =
    Appearance.prototype.getFragmentShaderSource;

  /**
   * Determines if the geometry is translucent based on {@link PolylineColorAppearance#translucent}.
   *
   * @function
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  PolylineColorAppearance.prototype.isTranslucent =
    Appearance.prototype.isTranslucent;

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @function
   *
   * @returns {Object} The render state.
   */
  PolylineColorAppearance.prototype.getRenderState =
    Appearance.prototype.getRenderState;

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineMaterialAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 prevPosition3DHigh;\n\
attribute vec3 prevPosition3DLow;\n\
attribute vec3 nextPosition3DHigh;\n\
attribute vec3 nextPosition3DLow;\n\
attribute vec2 expandAndWidth;\n\
attribute vec2 st;\n\
attribute float batchId;\n\
varying float v_width;\n\
varying vec2 v_st;\n\
varying float v_polylineAngle;\n\
void main()\n\
{\n\
float expandDir = expandAndWidth.x;\n\
float width = abs(expandAndWidth.y) + 0.5;\n\
bool usePrev = expandAndWidth.y < 0.0;\n\
vec4 p = czm_computePosition();\n\
vec4 prev = czm_computePrevPosition();\n\
vec4 next = czm_computeNextPosition();\n\
float angle;\n\
vec4 positionWC = getPolylineWindowCoordinates(p, prev, next, expandDir, width, usePrev, angle);\n\
gl_Position = czm_viewportOrthographic * positionWC;\n\
v_width = width;\n\
v_st.s = st.s;\n\
v_st.t = czm_writeNonPerspective(st.t, gl_Position.w);\n\
v_polylineAngle = angle;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineFS = "#ifdef VECTOR_TILE\n\
uniform vec4 u_highlightColor;\n\
#endif\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
czm_materialInput materialInput;\n\
vec2 st = v_st;\n\
st.t = czm_readNonPerspective(st.t, gl_FragCoord.w);\n\
materialInput.s = st.s;\n\
materialInput.st = st;\n\
materialInput.str = vec3(st, 0.0);\n\
czm_material material = czm_getMaterial(materialInput);\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#ifdef VECTOR_TILE\n\
gl_FragColor *= u_highlightColor;\n\
#endif\n\
czm_writeLogDepth();\n\
}\n\
";

  var defaultVertexShaderSource$1 =
    PolylineCommon + "\n" + PolylineMaterialAppearanceVS;
  var defaultFragmentShaderSource$1 = PolylineFS;

  if (!FeatureDetection.isInternetExplorer()) {
    defaultVertexShaderSource$1 =
      "#define CLIP_POLYLINE \n" + defaultVertexShaderSource$1;
  }

  /**
   * An appearance for {@link PolylineGeometry} that supports shading with materials.
   *
   * @alias PolylineMaterialAppearance
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.translucent=true] When <code>true</code>, the geometry is expected to appear translucent so {@link PolylineMaterialAppearance#renderState} has alpha blending enabled.
   * @param {Material} [options.material=Material.ColorType] The material used to determine the fragment color.
   * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
   * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
   * @param {Object} [options.renderState] Optional render state to override the default render state.
   *
   * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
   *
   * @example
   * var primitive = new Cesium.Primitive({
   *   geometryInstances : new Cesium.GeometryInstance({
   *     geometry : new Cesium.PolylineGeometry({
   *       positions : Cesium.Cartesian3.fromDegreesArray([
   *         0.0, 0.0,
   *         5.0, 0.0
   *       ]),
   *       width : 10.0,
   *       vertexFormat : Cesium.PolylineMaterialAppearance.VERTEX_FORMAT
   *     })
   *   }),
   *   appearance : new Cesium.PolylineMaterialAppearance({
   *     material : Cesium.Material.fromType('Color')
   *   })
   * });
   */
  function PolylineMaterialAppearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var translucent = defaultValue(options.translucent, true);
    var closed = false;
    var vertexFormat = PolylineMaterialAppearance.VERTEX_FORMAT;

    /**
     * The material used to determine the fragment color.  Unlike other {@link PolylineMaterialAppearance}
     * properties, this is not read-only, so an appearance's material can change on the fly.
     *
     * @type Material
     *
     * @default {@link Material.ColorType}
     *
     * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
     */
    this.material = defined(options.material)
      ? options.material
      : Material.fromType(Material.ColorType);

    /**
     * When <code>true</code>, the geometry is expected to appear translucent so
     * {@link PolylineMaterialAppearance#renderState} has alpha blending enabled.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.translucent = translucent;

    this._vertexShaderSource = defaultValue(
      options.vertexShaderSource,
      defaultVertexShaderSource$1
    );
    this._fragmentShaderSource = defaultValue(
      options.fragmentShaderSource,
      defaultFragmentShaderSource$1
    );
    this._renderState = Appearance.getDefaultRenderState(
      translucent,
      closed,
      options.renderState
    );
    this._closed = closed;

    // Non-derived members

    this._vertexFormat = vertexFormat;
  }

  Object.defineProperties(PolylineMaterialAppearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof PolylineMaterialAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        var vs = this._vertexShaderSource;
        if (
          this.material.shaderSource.search(
            /varying\s+float\s+v_polylineAngle;/g
          ) !== -1
        ) {
          vs = "#define POLYLINE_DASH\n" + vs;
        }
        return vs;
      },
    },

    /**
     * The GLSL source code for the fragment shader.
     *
     * @memberof PolylineMaterialAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     * <p>
     * The render state can be explicitly defined when constructing a {@link PolylineMaterialAppearance}
     * instance, or it is set implicitly via {@link PolylineMaterialAppearance#translucent}
     * and {@link PolylineMaterialAppearance#closed}.
     * </p>
     *
     * @memberof PolylineMaterialAppearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed so
     * {@link PolylineMaterialAppearance#renderState} has backface culling enabled.
     * This is always <code>false</code> for <code>PolylineMaterialAppearance</code>.
     *
     * @memberof PolylineMaterialAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },

    /**
     * The {@link VertexFormat} that this appearance instance is compatible with.
     * A geometry can have more vertex attributes and still be compatible - at a
     * potential performance cost - but it can't have less.
     *
     * @memberof PolylineMaterialAppearance.prototype
     *
     * @type VertexFormat
     * @readonly
     *
     * @default {@link PolylineMaterialAppearance.VERTEX_FORMAT}
     */
    vertexFormat: {
      get: function () {
        return this._vertexFormat;
      },
    },
  });

  /**
   * The {@link VertexFormat} that all {@link PolylineMaterialAppearance} instances
   * are compatible with. This requires <code>position</code> and <code>st</code> attributes.
   *
   * @type VertexFormat
   *
   * @constant
   */
  PolylineMaterialAppearance.VERTEX_FORMAT = VertexFormat.POSITION_AND_ST;

  /**
   * Procedurally creates the full GLSL fragment shader source.  For {@link PolylineMaterialAppearance},
   * this is derived from {@link PolylineMaterialAppearance#fragmentShaderSource} and {@link PolylineMaterialAppearance#material}.
   *
   * @function
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  PolylineMaterialAppearance.prototype.getFragmentShaderSource =
    Appearance.prototype.getFragmentShaderSource;

  /**
   * Determines if the geometry is translucent based on {@link PolylineMaterialAppearance#translucent} and {@link Material#isTranslucent}.
   *
   * @function
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  PolylineMaterialAppearance.prototype.isTranslucent =
    Appearance.prototype.isTranslucent;

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @function
   *
   * @returns {Object} The render state.
   */
  PolylineMaterialAppearance.prototype.getRenderState =
    Appearance.prototype.getRenderState;

  /**
   * A GroundPolylinePrimitive represents a polyline draped over the terrain or 3D Tiles in the {@link Scene}.
   * <p>
   * Only to be used with GeometryInstances containing {@link GroundPolylineGeometry}.
   * </p>
   *
   * @alias GroundPolylinePrimitive
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Array|GeometryInstance} [options.geometryInstances] GeometryInstances containing GroundPolylineGeometry
   * @param {Appearance} [options.appearance] The Appearance used to render the polyline. Defaults to a white color {@link Material} on a {@link PolylineMaterialAppearance}.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Boolean} [options.interleave=false] When <code>true</code>, geometry vertex attributes are interleaved, which can slightly improve rendering performance but increases load time.
   * @param {Boolean} [options.releaseGeometryInstances=true] When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
   * @param {Boolean} [options.asynchronous=true] Determines if the primitive will be created asynchronously or block until ready. If false initializeTerrainHeights() must be called first.
   * @param {ClassificationType} [options.classificationType=ClassificationType.BOTH] Determines whether terrain, 3D Tiles or both will be classified.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {Boolean} [options.debugShowShadowVolume=false] For debugging only. Determines if the shadow volume for each geometry in the primitive is drawn. Must be <code>true</code> on creation to have effect.
   *
   * @example
   * // 1. Draw a polyline on terrain with a basic color material
   *
   * var instance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.GroundPolylineGeometry({
   *      positions : Cesium.Cartesian3.fromDegreesArray([
   *          -112.1340164450331, 36.05494287836128,
   *          -112.08821010582645, 36.097804071380715
   *      ]),
   *      width : 4.0
   *   }),
   *   id : 'object returned when this instance is picked and to get/set per-instance attributes'
   * });
   *
   * scene.groundPrimitives.add(new Cesium.GroundPolylinePrimitive({
   *   geometryInstances : instance,
   *   appearance : new Cesium.PolylineMaterialAppearance()
   * }));
   *
   * // 2. Draw a looped polyline on terrain with per-instance color and a distance display condition.
   * // Distance display conditions for polylines on terrain are based on an approximate terrain height
   * // instead of true terrain height.
   *
   * var instance = new Cesium.GeometryInstance({
   *   geometry : new Cesium.GroundPolylineGeometry({
   *      positions : Cesium.Cartesian3.fromDegreesArray([
   *          -112.1340164450331, 36.05494287836128,
   *          -112.08821010582645, 36.097804071380715,
   *          -112.13296079730024, 36.168769146801104
   *      ]),
   *      loop : true,
   *      width : 4.0
   *   }),
   *   attributes : {
   *      color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromCssColorString('green').withAlpha(0.7)),
   *      distanceDisplayCondition : new Cesium.DistanceDisplayConditionGeometryInstanceAttribute(1000, 30000)
   *   },
   *   id : 'object returned when this instance is picked and to get/set per-instance attributes'
   * });
   *
   * scene.groundPrimitives.add(new Cesium.GroundPolylinePrimitive({
   *   geometryInstances : instance,
   *   appearance : new Cesium.PolylineColorAppearance()
   * }));
   */
  function GroundPolylinePrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The geometry instances rendered with this primitive. This may
     * be <code>undefined</code> if <code>options.releaseGeometryInstances</code>
     * is <code>true</code> when the primitive is constructed.
     * <p>
     * Changing this property after the primitive is rendered has no effect.
     * </p>
     *
     * @readonly
     * @type {Array|GeometryInstance}
     *
     * @default undefined
     */
    this.geometryInstances = options.geometryInstances;
    this._hasPerInstanceColors = true;

    var appearance = options.appearance;
    if (!defined(appearance)) {
      appearance = new PolylineMaterialAppearance();
    }
    /**
     * The {@link Appearance} used to shade this primitive. Each geometry
     * instance is shaded with the same appearance.  Some appearances, like
     * {@link PolylineColorAppearance} allow giving each instance unique
     * properties.
     *
     * @type Appearance
     *
     * @default undefined
     */
    this.appearance = appearance;

    /**
     * Determines if the primitive will be shown.  This affects all geometry
     * instances in the primitive.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * Determines whether terrain, 3D Tiles or both will be classified.
     *
     * @type {ClassificationType}
     *
     * @default ClassificationType.BOTH
     */
    this.classificationType = defaultValue(
      options.classificationType,
      ClassificationType$1.BOTH
    );

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    // Shadow volume is shown by removing a discard in the shader, so this isn't toggleable.
    this._debugShowShadowVolume = defaultValue(
      options.debugShowShadowVolume,
      false
    );

    this._primitiveOptions = {
      geometryInstances: undefined,
      appearance: undefined,
      vertexCacheOptimize: false,
      interleave: defaultValue(options.interleave, false),
      releaseGeometryInstances: defaultValue(
        options.releaseGeometryInstances,
        true
      ),
      allowPicking: defaultValue(options.allowPicking, true),
      asynchronous: defaultValue(options.asynchronous, true),
      compressVertices: false,
      _createShaderProgramFunction: undefined,
      _createCommandsFunction: undefined,
      _updateAndQueueCommandsFunction: undefined,
    };

    // Used when inserting in an OrderedPrimitiveCollection
    this._zIndex = undefined;

    this._ready = false;
    this._readyPromise = when.defer();

    this._primitive = undefined;

    this._sp = undefined;
    this._sp2D = undefined;
    this._spMorph = undefined;

    this._renderState = getRenderState(false);
    this._renderState3DTiles = getRenderState(true);

    this._renderStateMorph = RenderState.fromCache({
      cull: {
        enabled: true,
        face: CullFace$1.FRONT, // Geometry is "inverted," so cull front when materials on volume instead of on terrain (morph)
      },
      depthTest: {
        enabled: true,
      },
      blending: BlendingState$1.PRE_MULTIPLIED_ALPHA_BLEND,
      depthMask: false,
    });
  }

  Object.defineProperties(GroundPolylinePrimitive.prototype, {
    /**
     * Determines if geometry vertex attributes are interleaved, which can slightly improve rendering performance.
     *
     * @memberof GroundPolylinePrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    interleave: {
      get: function () {
        return this._primitiveOptions.interleave;
      },
    },

    /**
     * When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
     *
     * @memberof GroundPolylinePrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    releaseGeometryInstances: {
      get: function () {
        return this._primitiveOptions.releaseGeometryInstances;
      },
    },

    /**
     * When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
     *
     * @memberof GroundPolylinePrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    allowPicking: {
      get: function () {
        return this._primitiveOptions.allowPicking;
      },
    },

    /**
     * Determines if the geometry instances will be created and batched on a web worker.
     *
     * @memberof GroundPolylinePrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    asynchronous: {
      get: function () {
        return this._primitiveOptions.asynchronous;
      },
    },

    /**
     * Determines if the primitive is complete and ready to render.  If this property is
     * true, the primitive will be rendered the next time that {@link GroundPolylinePrimitive#update}
     * is called.
     *
     * @memberof GroundPolylinePrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof GroundPolylinePrimitive.prototype
     * @type {Promise.<GroundPolylinePrimitive>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * If true, draws the shadow volume for each geometry in the primitive.
     * </p>
     *
     * @memberof GroundPolylinePrimitive.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    debugShowShadowVolume: {
      get: function () {
        return this._debugShowShadowVolume;
      },
    },
  });

  /**
   * Initializes the minimum and maximum terrain heights. This only needs to be called if you are creating the
   * GroundPolylinePrimitive synchronously.
   *
   * @returns {Promise<void>} A promise that will resolve once the terrain heights have been loaded.
   */
  GroundPolylinePrimitive.initializeTerrainHeights = function () {
    return ApproximateTerrainHeights.initialize();
  };

  function createShaderProgram$2(groundPolylinePrimitive, frameState, appearance) {
    var context = frameState.context;
    var primitive = groundPolylinePrimitive._primitive;
    var attributeLocations = primitive._attributeLocations;

    var vs = primitive._batchTable.getVertexShaderCallback()(
      PolylineShadowVolumeVS
    );
    vs = Primitive._appendShowToShader(primitive, vs);
    vs = Primitive._appendDistanceDisplayConditionToShader(primitive, vs);
    vs = Primitive._modifyShaderPosition(
      groundPolylinePrimitive,
      vs,
      frameState.scene3DOnly
    );

    var vsMorph = primitive._batchTable.getVertexShaderCallback()(
      PolylineShadowVolumeMorphVS
    );
    vsMorph = Primitive._appendShowToShader(primitive, vsMorph);
    vsMorph = Primitive._appendDistanceDisplayConditionToShader(
      primitive,
      vsMorph
    );
    vsMorph = Primitive._modifyShaderPosition(
      groundPolylinePrimitive,
      vsMorph,
      frameState.scene3DOnly
    );

    // Access pick color from fragment shader.
    // Helps with varying budget.
    var fs = primitive._batchTable.getVertexShaderCallback()(
      PolylineShadowVolumeFS
    );

    var vsDefines = [
      "GLOBE_MINIMUM_ALTITUDE " +
        frameState.mapProjection.ellipsoid.minimumRadius.toFixed(1),
    ];
    var colorDefine = "";
    var materialShaderSource = "";
    if (defined(appearance.material)) {
      materialShaderSource = defined(appearance.material)
        ? appearance.material.shaderSource
        : "";

      // Check for use of v_width and v_polylineAngle in material shader
      // to determine whether these varyings should be active in the vertex shader.
      if (
        materialShaderSource.search(/varying\s+float\s+v_polylineAngle;/g) !== -1
      ) {
        vsDefines.push("ANGLE_VARYING");
      }
      if (materialShaderSource.search(/varying\s+float\s+v_width;/g) !== -1) {
        vsDefines.push("WIDTH_VARYING");
      }
    } else {
      colorDefine = "PER_INSTANCE_COLOR";
    }

    vsDefines.push(colorDefine);
    var fsDefines = groundPolylinePrimitive.debugShowShadowVolume
      ? ["DEBUG_SHOW_VOLUME", colorDefine]
      : [colorDefine];

    var vsColor3D = new ShaderSource({
      defines: vsDefines,
      sources: [vs],
    });
    var fsColor3D = new ShaderSource({
      defines: fsDefines,
      sources: [materialShaderSource, fs],
    });
    groundPolylinePrimitive._sp = ShaderProgram.replaceCache({
      context: context,
      shaderProgram: primitive._sp,
      vertexShaderSource: vsColor3D,
      fragmentShaderSource: fsColor3D,
      attributeLocations: attributeLocations,
    });

    // Derive 2D/CV
    var colorProgram2D = context.shaderCache.getDerivedShaderProgram(
      groundPolylinePrimitive._sp,
      "2dColor"
    );
    if (!defined(colorProgram2D)) {
      var vsColor2D = new ShaderSource({
        defines: vsDefines.concat(["COLUMBUS_VIEW_2D"]),
        sources: [vs],
      });
      colorProgram2D = context.shaderCache.createDerivedShaderProgram(
        groundPolylinePrimitive._sp,
        "2dColor",
        {
          context: context,
          shaderProgram: groundPolylinePrimitive._sp2D,
          vertexShaderSource: vsColor2D,
          fragmentShaderSource: fsColor3D,
          attributeLocations: attributeLocations,
        }
      );
    }
    groundPolylinePrimitive._sp2D = colorProgram2D;

    // Derive Morph
    var colorProgramMorph = context.shaderCache.getDerivedShaderProgram(
      groundPolylinePrimitive._sp,
      "MorphColor"
    );
    if (!defined(colorProgramMorph)) {
      var vsColorMorph = new ShaderSource({
        defines: vsDefines.concat([
          "MAX_TERRAIN_HEIGHT " +
            ApproximateTerrainHeights._defaultMaxTerrainHeight.toFixed(1),
        ]),
        sources: [vsMorph],
      });

      fs = primitive._batchTable.getVertexShaderCallback()(
        PolylineShadowVolumeMorphFS
      );
      var fsColorMorph = new ShaderSource({
        defines: fsDefines,
        sources: [materialShaderSource, fs],
      });
      colorProgramMorph = context.shaderCache.createDerivedShaderProgram(
        groundPolylinePrimitive._sp,
        "MorphColor",
        {
          context: context,
          shaderProgram: groundPolylinePrimitive._spMorph,
          vertexShaderSource: vsColorMorph,
          fragmentShaderSource: fsColorMorph,
          attributeLocations: attributeLocations,
        }
      );
    }
    groundPolylinePrimitive._spMorph = colorProgramMorph;
  }

  function getRenderState(mask3DTiles) {
    return RenderState.fromCache({
      cull: {
        enabled: true, // prevent double-draw. Geometry is "inverted" (reversed winding order) so we're drawing backfaces.
      },
      blending: BlendingState$1.PRE_MULTIPLIED_ALPHA_BLEND,
      depthMask: false,
      stencilTest: {
        enabled: mask3DTiles,
        frontFunction: StencilFunction$1.EQUAL,
        frontOperation: {
          fail: StencilOperation$1.KEEP,
          zFail: StencilOperation$1.KEEP,
          zPass: StencilOperation$1.KEEP,
        },
        backFunction: StencilFunction$1.EQUAL,
        backOperation: {
          fail: StencilOperation$1.KEEP,
          zFail: StencilOperation$1.KEEP,
          zPass: StencilOperation$1.KEEP,
        },
        reference: StencilConstants$1.CESIUM_3D_TILE_MASK,
        mask: StencilConstants$1.CESIUM_3D_TILE_MASK,
      },
    });
  }

  function createCommands$2(
    groundPolylinePrimitive,
    appearance,
    material,
    translucent,
    colorCommands,
    pickCommands
  ) {
    var primitive = groundPolylinePrimitive._primitive;
    var length = primitive._va.length;
    colorCommands.length = length;
    pickCommands.length = length;

    var isPolylineColorAppearance = appearance instanceof PolylineColorAppearance;

    var materialUniforms = isPolylineColorAppearance ? {} : material._uniforms;
    var uniformMap = primitive._batchTable.getUniformMapCallback()(
      materialUniforms
    );

    for (var i = 0; i < length; i++) {
      var vertexArray = primitive._va[i];

      var command = colorCommands[i];
      if (!defined(command)) {
        command = colorCommands[i] = new DrawCommand({
          owner: groundPolylinePrimitive,
          primitiveType: primitive._primitiveType,
        });
      }

      command.vertexArray = vertexArray;
      command.renderState = groundPolylinePrimitive._renderState;
      command.shaderProgram = groundPolylinePrimitive._sp;
      command.uniformMap = uniformMap;
      command.pass = Pass$1.TERRAIN_CLASSIFICATION;
      command.pickId = "czm_batchTable_pickColor(v_endPlaneNormalEcAndBatchId.w)";

      var derivedTilesetCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.tileset
      );
      derivedTilesetCommand.renderState =
        groundPolylinePrimitive._renderState3DTiles;
      derivedTilesetCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      command.derivedCommands.tileset = derivedTilesetCommand;

      // derive for 2D
      var derived2DCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.color2D
      );
      derived2DCommand.shaderProgram = groundPolylinePrimitive._sp2D;
      command.derivedCommands.color2D = derived2DCommand;

      var derived2DTilesetCommand = DrawCommand.shallowClone(
        derivedTilesetCommand,
        derivedTilesetCommand.derivedCommands.color2D
      );
      derived2DTilesetCommand.shaderProgram = groundPolylinePrimitive._sp2D;
      derivedTilesetCommand.derivedCommands.color2D = derived2DTilesetCommand;

      // derive for Morph
      var derivedMorphCommand = DrawCommand.shallowClone(
        command,
        command.derivedCommands.colorMorph
      );
      derivedMorphCommand.renderState = groundPolylinePrimitive._renderStateMorph;
      derivedMorphCommand.shaderProgram = groundPolylinePrimitive._spMorph;
      derivedMorphCommand.pickId = "czm_batchTable_pickColor(v_batchId)";
      command.derivedCommands.colorMorph = derivedMorphCommand;
    }
  }

  function updateAndQueueCommand(
    groundPolylinePrimitive,
    command,
    frameState,
    modelMatrix,
    cull,
    boundingVolume,
    debugShowBoundingVolume
  ) {
    // Use derived appearance command for morph and 2D
    if (frameState.mode === SceneMode$1.MORPHING) {
      command = command.derivedCommands.colorMorph;
    } else if (frameState.mode !== SceneMode$1.SCENE3D) {
      command = command.derivedCommands.color2D;
    }
    command.modelMatrix = modelMatrix;
    command.boundingVolume = boundingVolume;
    command.cull = cull;
    command.debugShowBoundingVolume = debugShowBoundingVolume;

    frameState.commandList.push(command);
  }

  function updateAndQueueCommands$3(
    groundPolylinePrimitive,
    frameState,
    colorCommands,
    pickCommands,
    modelMatrix,
    cull,
    debugShowBoundingVolume
  ) {
    var primitive = groundPolylinePrimitive._primitive;

    Primitive._updateBoundingVolumes(primitive, frameState, modelMatrix); // Expected to be identity - GroundPrimitives don't support other model matrices

    var boundingSpheres;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      boundingSpheres = primitive._boundingSphereWC;
    } else if (frameState.mode === SceneMode$1.COLUMBUS_VIEW) {
      boundingSpheres = primitive._boundingSphereCV;
    } else if (
      frameState.mode === SceneMode$1.SCENE2D &&
      defined(primitive._boundingSphere2D)
    ) {
      boundingSpheres = primitive._boundingSphere2D;
    } else if (defined(primitive._boundingSphereMorph)) {
      boundingSpheres = primitive._boundingSphereMorph;
    }

    var morphing = frameState.mode === SceneMode$1.MORPHING;
    var classificationType = groundPolylinePrimitive.classificationType;
    var queueTerrainCommands =
      classificationType !== ClassificationType$1.CESIUM_3D_TILE;
    var queue3DTilesCommands =
      classificationType !== ClassificationType$1.TERRAIN && !morphing;

    var command;
    var passes = frameState.passes;
    if (passes.render || (passes.pick && primitive.allowPicking)) {
      var colorLength = colorCommands.length;
      for (var j = 0; j < colorLength; ++j) {
        var boundingVolume = boundingSpheres[j];
        if (queueTerrainCommands) {
          command = colorCommands[j];
          updateAndQueueCommand(
            groundPolylinePrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
        if (queue3DTilesCommands) {
          command = colorCommands[j].derivedCommands.tileset;
          updateAndQueueCommand(
            groundPolylinePrimitive,
            command,
            frameState,
            modelMatrix,
            cull,
            boundingVolume,
            debugShowBoundingVolume
          );
        }
      }
    }
  }

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} For synchronous GroundPolylinePrimitives, you must call GroundPolylinePrimitives.initializeTerrainHeights() and wait for the returned promise to resolve.
   * @exception {DeveloperError} All GeometryInstances must have color attributes to use PolylineColorAppearance with GroundPolylinePrimitive.
   */
  GroundPolylinePrimitive.prototype.update = function (frameState) {
    if (!defined(this._primitive) && !defined(this.geometryInstances)) {
      return;
    }

    if (!ApproximateTerrainHeights.initialized) {
      //>>includeStart('debug', pragmas.debug);
      if (!this.asynchronous) {
        throw new DeveloperError(
          "For synchronous GroundPolylinePrimitives, you must call GroundPolylinePrimitives.initializeTerrainHeights() and wait for the returned promise to resolve."
        );
      }
      //>>includeEnd('debug');

      GroundPolylinePrimitive.initializeTerrainHeights();
      return;
    }

    var i;

    var that = this;
    var primitiveOptions = this._primitiveOptions;
    if (!defined(this._primitive)) {
      var geometryInstances = Array.isArray(this.geometryInstances)
        ? this.geometryInstances
        : [this.geometryInstances];
      var geometryInstancesLength = geometryInstances.length;
      var groundInstances = new Array(geometryInstancesLength);

      var attributes;

      // Check if each instance has a color attribute.
      for (i = 0; i < geometryInstancesLength; ++i) {
        attributes = geometryInstances[i].attributes;
        if (!defined(attributes) || !defined(attributes.color)) {
          this._hasPerInstanceColors = false;
          break;
        }
      }

      for (i = 0; i < geometryInstancesLength; ++i) {
        var geometryInstance = geometryInstances[i];
        attributes = {};
        var instanceAttributes = geometryInstance.attributes;
        for (var attributeKey in instanceAttributes) {
          if (instanceAttributes.hasOwnProperty(attributeKey)) {
            attributes[attributeKey] = instanceAttributes[attributeKey];
          }
        }

        // Automatically create line width attribute if not already given
        if (!defined(attributes.width)) {
          attributes.width = new GeometryInstanceAttribute({
            componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
            componentsPerAttribute: 1.0,
            value: [geometryInstance.geometry.width],
          });
        }

        // Update each geometry for framestate.scene3DOnly = true and projection
        geometryInstance.geometry._scene3DOnly = frameState.scene3DOnly;
        GroundPolylineGeometry.setProjectionAndEllipsoid(
          geometryInstance.geometry,
          frameState.mapProjection
        );

        groundInstances[i] = new GeometryInstance({
          geometry: geometryInstance.geometry,
          attributes: attributes,
          id: geometryInstance.id,
          pickPrimitive: that,
        });
      }

      primitiveOptions.geometryInstances = groundInstances;
      primitiveOptions.appearance = this.appearance;

      primitiveOptions._createShaderProgramFunction = function (
        primitive,
        frameState,
        appearance
      ) {
        createShaderProgram$2(that, frameState, appearance);
      };
      primitiveOptions._createCommandsFunction = function (
        primitive,
        appearance,
        material,
        translucent,
        twoPasses,
        colorCommands,
        pickCommands
      ) {
        createCommands$2(
          that,
          appearance,
          material,
          translucent,
          colorCommands,
          pickCommands
        );
      };
      primitiveOptions._updateAndQueueCommandsFunction = function (
        primitive,
        frameState,
        colorCommands,
        pickCommands,
        modelMatrix,
        cull,
        debugShowBoundingVolume,
        twoPasses
      ) {
        updateAndQueueCommands$3(
          that,
          frameState,
          colorCommands,
          pickCommands,
          modelMatrix,
          cull,
          debugShowBoundingVolume
        );
      };

      this._primitive = new Primitive(primitiveOptions);
      this._primitive.readyPromise.then(function (primitive) {
        that._ready = true;

        if (that.releaseGeometryInstances) {
          that.geometryInstances = undefined;
        }

        var error = primitive._error;
        if (!defined(error)) {
          that._readyPromise.resolve(that);
        } else {
          that._readyPromise.reject(error);
        }
      });
    }

    if (
      this.appearance instanceof PolylineColorAppearance &&
      !this._hasPerInstanceColors
    ) {
      throw new DeveloperError(
        "All GeometryInstances must have color attributes to use PolylineColorAppearance with GroundPolylinePrimitive."
      );
    }

    this._primitive.appearance = this.appearance;
    this._primitive.show = this.show;
    this._primitive.debugShowBoundingVolume = this.debugShowBoundingVolume;
    this._primitive.update(frameState);
  };

  /**
   * Returns the modifiable per-instance attributes for a {@link GeometryInstance}.
   *
   * @param {*} id The id of the {@link GeometryInstance}.
   * @returns {Object} The typed array in the attribute's format or undefined if the is no instance with id.
   *
   * @exception {DeveloperError} must call update before calling getGeometryInstanceAttributes.
   *
   * @example
   * var attributes = primitive.getGeometryInstanceAttributes('an id');
   * attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA);
   * attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true);
   */
  GroundPolylinePrimitive.prototype.getGeometryInstanceAttributes = function (
    id
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(this._primitive)) {
      throw new DeveloperError(
        "must call update before calling getGeometryInstanceAttributes"
      );
    }
    //>>includeEnd('debug');
    return this._primitive.getGeometryInstanceAttributes(id);
  };

  /**
   * Checks if the given Scene supports GroundPolylinePrimitives.
   * GroundPolylinePrimitives require support for the WEBGL_depth_texture extension.
   *
   * @param {Scene} scene The current scene.
   * @returns {Boolean} Whether or not the current scene supports GroundPolylinePrimitives.
   */
  GroundPolylinePrimitive.isSupported = function (scene) {
    return scene.frameState.context.depthTexture;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see GroundPolylinePrimitive#destroy
   */
  GroundPolylinePrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * e = e && e.destroy();
   *
   * @see GroundPolylinePrimitive#isDestroyed
   */
  GroundPolylinePrimitive.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    this._sp = this._sp && this._sp.destroy();

    // Derived programs, destroyed above if they existed.
    this._sp2D = undefined;
    this._spMorph = undefined;

    return destroyObject(this);
  };

  var defaultRepeat = new Cartesian2(1, 1);
  var defaultTransparent = false;
  var defaultColor$1 = Color.WHITE;

  /**
   * A {@link MaterialProperty} that maps to image {@link Material} uniforms.
   * @alias ImageMaterialProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|String|HTMLImageElement|HTMLCanvasElement|HTMLVideoElement} [options.image] A Property specifying the Image, URL, Canvas, or Video.
   * @param {Property|Cartesian2} [options.repeat=new Cartesian2(1.0, 1.0)] A {@link Cartesian2} Property specifying the number of times the image repeats in each direction.
   * @param {Property|Color} [options.color=Color.WHITE] The color applied to the image
   * @param {Property|Boolean} [options.transparent=false] Set to true when the image has transparency (for example, when a png has transparent sections)
   */
  function ImageMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._image = undefined;
    this._imageSubscription = undefined;
    this._repeat = undefined;
    this._repeatSubscription = undefined;
    this._color = undefined;
    this._colorSubscription = undefined;
    this._transparent = undefined;
    this._transparentSubscription = undefined;

    this.image = options.image;
    this.repeat = options.repeat;
    this.color = options.color;
    this.transparent = options.transparent;
  }

  Object.defineProperties(ImageMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof ImageMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._image) && Property.isConstant(this._repeat)
        );
      },
    },

    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof ImageMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the Property specifying Image, URL, Canvas, or Video to use.
     * @memberof ImageMaterialProperty.prototype
     * @type {Property|undefined}
     */
    image: createPropertyDescriptor("image"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the number of times the image repeats in each direction.
     * @memberof ImageMaterialProperty.prototype
     * @type {Property|undefined}
     * @default new Cartesian2(1, 1)
     */
    repeat: createPropertyDescriptor("repeat"),

    /**
     * Gets or sets the Color Property specifying the desired color applied to the image.
     * @memberof ImageMaterialProperty.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the Boolean Property specifying whether the image has transparency
     * @memberof ImageMaterialProperty.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    transparent: createPropertyDescriptor("transparent"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  ImageMaterialProperty.prototype.getType = function (time) {
    return "Image";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ImageMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }

    result.image = Property.getValueOrUndefined(this._image, time);
    result.repeat = Property.getValueOrClonedDefault(
      this._repeat,
      time,
      defaultRepeat,
      result.repeat
    );
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      defaultColor$1,
      result.color
    );
    if (Property.getValueOrDefault(this._transparent, time, defaultTransparent)) {
      result.color.alpha = Math.min(0.99, result.color.alpha);
    }

    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  ImageMaterialProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof ImageMaterialProperty &&
        Property.equals(this._image, other._image) &&
        Property.equals(this._repeat, other._repeat) &&
        Property.equals(this._color, other._color) &&
        Property.equals(this._transparent, other._transparent))
    );
  };

  function createMaterialProperty(value) {
    if (value instanceof Color) {
      return new ColorMaterialProperty(value);
    }

    if (
      typeof value === "string" ||
      value instanceof Resource ||
      value instanceof HTMLCanvasElement ||
      value instanceof HTMLVideoElement
    ) {
      var result = new ImageMaterialProperty();
      result.image = value;
      return result;
    }

    //>>includeStart('debug', pragmas.debug);
    throw new DeveloperError("Unable to infer material type: " + value);
    //>>includeEnd('debug');
  }

  /**
   * @private
   */
  function createMaterialPropertyDescriptor(name, configurable) {
    return createPropertyDescriptor(name, configurable, createMaterialProperty);
  }

  /**
   * @typedef {Object} BoxGraphics.ConstructorOptions
   *
   * Initialization options for the BoxGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the box.
   * @property {Property | Cartesian3} [dimensions] A {@link Cartesian3} Property specifying the length, width, and height of the box.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height from the entity position is relative to.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the box is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the box.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the box is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the box casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this box will be displayed.
   *
   */

  /**
   * Describes a box. The center position and orientation are determined by the containing {@link Entity}.
   *
   * @alias BoxGraphics
   * @constructor
   *
   * @param {BoxGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Box.html|Cesium Sandcastle Box Demo}
   */
  function BoxGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._dimensions = undefined;
    this._dimensionsSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(BoxGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof BoxGraphics.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the box.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets {@link Cartesian3} Property property specifying the length, width, and height of the box.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     */
    dimensions: createPropertyDescriptor("dimensions"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the boolean Property specifying whether the box is filled with the provided material.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the material used to fill the box.
     * @memberof BoxGraphics.prototype
     * @type {MaterialProperty|undefined}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the box is outlined.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Get or sets the enum Property specifying whether the box
     * casts or receives shadows from light sources.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this box will be displayed.
     * @memberof BoxGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {BoxGraphics} [result] The object onto which to store the result.
   * @returns {BoxGraphics} The modified result parameter or a new instance if one was not provided.
   */
  BoxGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new BoxGraphics(this);
    }
    result.show = this.show;
    result.dimensions = this.dimensions;
    result.heightReference = this.heightReference;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {BoxGraphics} source The object to be merged into this object.
   */
  BoxGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.dimensions = defaultValue(this.dimensions, source.dimensions);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  /**
   * The interface for all {@link Property} objects that define a world
   * location as a {@link Cartesian3} with an associated {@link ReferenceFrame}.
   * This type defines an interface and cannot be instantiated directly.
   *
   * @alias PositionProperty
   * @constructor
   * @abstract
   *
   * @see CompositePositionProperty
   * @see ConstantPositionProperty
   * @see SampledPositionProperty
   * @see TimeIntervalCollectionPositionProperty
   */
  function PositionProperty() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(PositionProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof PositionProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof PositionProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets the reference frame that the position is defined in.
     * @memberof PositionProperty.prototype
     * @type {ReferenceFrame}
     */
    referenceFrame: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Gets the value of the property at the provided time in the fixed frame.
   * @function
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PositionProperty.prototype.getValue = DeveloperError.throwInstantiationError;

  /**
   * Gets the value of the property at the provided time and in the provided reference frame.
   * @function
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PositionProperty.prototype.getValueInReferenceFrame =
    DeveloperError.throwInstantiationError;

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   * @function
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PositionProperty.prototype.equals = DeveloperError.throwInstantiationError;

  var scratchMatrix3 = new Matrix3();

  /**
   * @private
   */
  PositionProperty.convertToReferenceFrame = function (
    time,
    value,
    inputFrame,
    outputFrame,
    result
  ) {
    if (!defined(value)) {
      return value;
    }
    if (!defined(result)) {
      result = new Cartesian3();
    }

    if (inputFrame === outputFrame) {
      return Cartesian3.clone(value, result);
    }

    var icrfToFixed = Transforms.computeIcrfToFixedMatrix(time, scratchMatrix3);
    if (!defined(icrfToFixed)) {
      icrfToFixed = Transforms.computeTemeToPseudoFixedMatrix(
        time,
        scratchMatrix3
      );
    }
    if (inputFrame === ReferenceFrame$1.INERTIAL) {
      return Matrix3.multiplyByVector(icrfToFixed, value, result);
    }
    if (inputFrame === ReferenceFrame$1.FIXED) {
      return Matrix3.multiplyByVector(
        Matrix3.transpose(icrfToFixed, scratchMatrix3),
        value,
        result
      );
    }
  };

  /**
   * A {@link PositionProperty} whose value does not change in respect to the
   * {@link ReferenceFrame} in which is it defined.
   *
   * @alias ConstantPositionProperty
   * @constructor
   *
   * @param {Cartesian3} [value] The property value.
   * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
   */
  function ConstantPositionProperty(value, referenceFrame) {
    this._definitionChanged = new Event();
    this._value = Cartesian3.clone(value);
    this._referenceFrame = defaultValue(referenceFrame, ReferenceFrame$1.FIXED);
  }

  Object.defineProperties(ConstantPositionProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof ConstantPositionProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          !defined(this._value) || this._referenceFrame === ReferenceFrame$1.FIXED
        );
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof ConstantPositionProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the reference frame in which the position is defined.
     * @memberof ConstantPositionProperty.prototype
     * @type {ReferenceFrame}
     * @default ReferenceFrame.FIXED;
     */
    referenceFrame: {
      get: function () {
        return this._referenceFrame;
      },
    },
  });

  /**
   * Gets the value of the property at the provided time in the fixed frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ConstantPositionProperty.prototype.getValue = function (time, result) {
    return this.getValueInReferenceFrame(time, ReferenceFrame$1.FIXED, result);
  };

  /**
   * Sets the value of the property.
   *
   * @param {Cartesian3} value The property value.
   * @param {ReferenceFrame} [referenceFrame=this.referenceFrame] The reference frame in which the position is defined.
   */
  ConstantPositionProperty.prototype.setValue = function (value, referenceFrame) {
    var definitionChanged = false;
    if (!Cartesian3.equals(this._value, value)) {
      definitionChanged = true;
      this._value = Cartesian3.clone(value);
    }
    if (defined(referenceFrame) && this._referenceFrame !== referenceFrame) {
      definitionChanged = true;
      this._referenceFrame = referenceFrame;
    }
    if (definitionChanged) {
      this._definitionChanged.raiseEvent(this);
    }
  };

  /**
   * Gets the value of the property at the provided time and in the provided reference frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ConstantPositionProperty.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    if (!defined(referenceFrame)) {
      throw new DeveloperError("referenceFrame is required.");
    }
    //>>includeEnd('debug');

    return PositionProperty.convertToReferenceFrame(
      time,
      this._value,
      this._referenceFrame,
      referenceFrame,
      result
    );
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  ConstantPositionProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof ConstantPositionProperty &&
        Cartesian3.equals(this._value, other._value) &&
        this._referenceFrame === other._referenceFrame)
    );
  };

  /**
   * @typedef {Object} CorridorGraphics.ConstructorOptions
   *
   * Initialization options for the CorridorGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the corridor.
   * @property {Property | Cartesian3} [positions] A Property specifying the array of {@link Cartesian3} positions that define the centerline of the corridor.
   * @property {Property | number} [width] A numeric Property specifying the distance between the edges of the corridor.
   * @property {Property | number} [height=0] A numeric Property specifying the altitude of the corridor relative to the ellipsoid surface.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | number} [extrudedHeight] A numeric Property specifying the altitude of the corridor's extruded face relative to the ellipsoid surface.
   * @property {Property | HeightReference} [extrudedHeightReference=HeightReference.NONE] A Property specifying what the extrudedHeight is relative to.
   * @property {Property | CornerType} [cornerType=CornerType.ROUNDED] A {@link CornerType} Property specifying the style of the corners.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the distance between each latitude and longitude.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the corridor is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the corridor.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the corridor is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the corridor casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this corridor will be displayed.
   * @property {Property | ClassificationType} [classificationType=ClassificationType.BOTH] An enum Property specifying whether this corridor will classify terrain, 3D Tiles, or both when on the ground.
   * @property {ConstantProperty | number} [zIndex] A Property specifying the zIndex of the corridor, used for ordering.  Only has an effect if height and extrudedHeight are undefined, and if the corridor is static.
   */

  /**
   * Describes a corridor, which is a shape defined by a centerline and width that
   * conforms to the curvature of the globe. It can be placed on the surface or at altitude
   * and can optionally be extruded into a volume.
   *
   * @alias CorridorGraphics
   * @constructor
   *
   * @param {CorridorGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see Entity
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Corridor.html|Cesium Sandcastle Corridor Demo}
   */
  function CorridorGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._positions = undefined;
    this._positionsSubscription = undefined;
    this._width = undefined;
    this._widthSubscription = undefined;
    this._height = undefined;
    this._heightSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._extrudedHeight = undefined;
    this._extrudedHeightSubscription = undefined;
    this._extrudedHeightReference = undefined;
    this._extrudedHeightReferenceSubscription = undefined;
    this._cornerType = undefined;
    this._cornerTypeSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._classificationType = undefined;
    this._classificationTypeSubscription = undefined;
    this._zIndex = undefined;
    this._zIndexSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(CorridorGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof CorridorGraphics.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the corridor.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets a Property specifying the array of {@link Cartesian3} positions that define the centerline of the corridor.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     */
    positions: createPropertyDescriptor("positions"),

    /**
     * Gets or sets the numeric Property specifying the width of the corridor.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     */
    width: createPropertyDescriptor("width"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the corridor.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    height: createPropertyDescriptor("height"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the corridor extrusion.
     * Setting this property creates a corridor shaped volume starting at height and ending
     * at this altitude.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     */
    extrudedHeight: createPropertyDescriptor("extrudedHeight"),

    /**
     * Gets or sets the Property specifying the extruded {@link HeightReference}.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    extrudedHeightReference: createPropertyDescriptor("extrudedHeightReference"),

    /**
     * Gets or sets the {@link CornerType} Property specifying how corners are styled.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default CornerType.ROUNDED
     */
    cornerType: createPropertyDescriptor("cornerType"),

    /**
     * Gets or sets the numeric Property specifying the sampling distance between each latitude and longitude point.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default {CesiumMath.RADIANS_PER_DEGREE}
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the boolean Property specifying whether the corridor is filled with the provided material.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the corridor.
     * @memberof CorridorGraphics.prototype
     * @type {MaterialProperty|undefined}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the corridor is outlined.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Get or sets the enum Property specifying whether the corridor
     * casts or receives shadows from light sources.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this corridor will be displayed.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the {@link ClassificationType} Property specifying whether this corridor will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof CorridorGraphics.prototype
     * @type {Property|undefined}
     * @default ClassificationType.BOTH
     */
    classificationType: createPropertyDescriptor("classificationType"),

    /**
     * Gets or sets the zIndex Property specifying the ordering of the corridor.  Only has an effect if the coridor is static and neither height or exturdedHeight are specified.
     * @memberof CorridorGraphics.prototype
     * @type {ConstantProperty|undefined}
     * @default 0
     */
    zIndex: createPropertyDescriptor("zIndex"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {CorridorGraphics} [result] The object onto which to store the result.
   * @returns {CorridorGraphics} The modified result parameter or a new instance if one was not provided.
   */
  CorridorGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new CorridorGraphics(this);
    }
    result.show = this.show;
    result.positions = this.positions;
    result.width = this.width;
    result.height = this.height;
    result.heightReference = this.heightReference;
    result.extrudedHeight = this.extrudedHeight;
    result.extrudedHeightReference = this.extrudedHeightReference;
    result.cornerType = this.cornerType;
    result.granularity = this.granularity;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.classificationType = this.classificationType;
    result.zIndex = this.zIndex;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {CorridorGraphics} source The object to be merged into this object.
   */
  CorridorGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.positions = defaultValue(this.positions, source.positions);
    this.width = defaultValue(this.width, source.width);
    this.height = defaultValue(this.height, source.height);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.extrudedHeight = defaultValue(
      this.extrudedHeight,
      source.extrudedHeight
    );
    this.extrudedHeightReference = defaultValue(
      this.extrudedHeightReference,
      source.extrudedHeightReference
    );
    this.cornerType = defaultValue(this.cornerType, source.cornerType);
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.classificationType = defaultValue(
      this.classificationType,
      source.classificationType
    );
    this.zIndex = defaultValue(this.zIndex, source.zIndex);
  };

  function createRawProperty(value) {
    return value;
  }

  /**
   * @private
   */
  function createRawPropertyDescriptor(name, configurable) {
    return createPropertyDescriptor(name, configurable, createRawProperty);
  }

  /**
   * @typedef {Object} CylinderGraphics.ConstructorOptions
   *
   * Initialization options for the CylinderGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the cylinder.
   * @property {Property | number} [length] A numeric Property specifying the length of the cylinder.
   * @property {Property | number} [topRadius] A numeric Property specifying the radius of the top of the cylinder.
   * @property {Property | number} [bottomRadius] A numeric Property specifying the radius of the bottom of the cylinder.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height from the entity position is relative to.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the cylinder is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the cylinder.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the cylinder is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | number} [numberOfVerticalLines=16] A numeric Property specifying the number of vertical lines to draw along the perimeter for the outline.
   * @property {Property | number} [slices=128] The number of edges around the perimeter of the cylinder.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the cylinder casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this cylinder will be displayed.
   */

  /**
   * Describes a cylinder, truncated cone, or cone defined by a length, top radius, and bottom radius.
   * The center position and orientation are determined by the containing {@link Entity}.
   *
   * @alias CylinderGraphics
   * @constructor
   *
   * @param {CylinderGraphics.ConstructorOptions} [options] Object describing initialization options
   */
  function CylinderGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._length = undefined;
    this._lengthSubscription = undefined;
    this._topRadius = undefined;
    this._topRadiusSubscription = undefined;
    this._bottomRadius = undefined;
    this._bottomRadiusSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._numberOfVerticalLines = undefined;
    this._numberOfVerticalLinesSubscription = undefined;
    this._slices = undefined;
    this._slicesSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(CylinderGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof CylinderGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the cylinder.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the numeric Property specifying the length of the cylinder.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     */
    length: createPropertyDescriptor("length"),

    /**
     * Gets or sets the numeric Property specifying the radius of the top of the cylinder.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     */
    topRadius: createPropertyDescriptor("topRadius"),

    /**
     * Gets or sets the numeric Property specifying the radius of the bottom of the cylinder.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     */
    bottomRadius: createPropertyDescriptor("bottomRadius"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the boolean Property specifying whether the cylinder is filled with the provided material.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the cylinder.
     * @memberof CylinderGraphics.prototype
     * @type {MaterialProperty|undefined}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the boolean Property specifying whether the cylinder is outlined.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Gets or sets the Property specifying the number of vertical lines to draw along the perimeter for the outline.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default 16
     */
    numberOfVerticalLines: createPropertyDescriptor("numberOfVerticalLines"),

    /**
     * Gets or sets the Property specifying the number of edges around the perimeter of the cylinder.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default 128
     */
    slices: createPropertyDescriptor("slices"),

    /**
     * Get or sets the enum Property specifying whether the cylinder
     * casts or receives shadows from light sources.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this cylinder will be displayed.
     * @memberof CylinderGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {CylinderGraphics} [result] The object onto which to store the result.
   * @returns {CylinderGraphics} The modified result parameter or a new instance if one was not provided.
   */
  CylinderGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new CylinderGraphics(this);
    }
    result.show = this.show;
    result.length = this.length;
    result.topRadius = this.topRadius;
    result.bottomRadius = this.bottomRadius;
    result.heightReference = this.heightReference;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.numberOfVerticalLines = this.numberOfVerticalLines;
    result.slices = this.slices;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {CylinderGraphics} source The object to be merged into this object.
   */
  CylinderGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.length = defaultValue(this.length, source.length);
    this.topRadius = defaultValue(this.topRadius, source.topRadius);
    this.bottomRadius = defaultValue(this.bottomRadius, source.bottomRadius);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.numberOfVerticalLines = defaultValue(
      this.numberOfVerticalLines,
      source.numberOfVerticalLines
    );
    this.slices = defaultValue(this.slices, source.slices);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  /**
   * @typedef {Object} EllipseGraphics.ConstructorOptions
   *
   * Initialization options for the EllipseGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the ellipse.
   * @property {Property | number} [semiMajorAxis] The numeric Property specifying the semi-major axis.
   * @property {Property | number} [semiMinorAxis] The numeric Property specifying the semi-minor axis.
   * @property {Property | number} [height=0] A numeric Property specifying the altitude of the ellipse relative to the ellipsoid surface.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | number} [extrudedHeight] A numeric Property specifying the altitude of the ellipse's extruded face relative to the ellipsoid surface.
   * @property {Property | HeightReference} [extrudedHeightReference=HeightReference.NONE] A Property specifying what the extrudedHeight is relative to.
   * @property {Property | number} [rotation=0.0] A numeric property specifying the rotation of the ellipse counter-clockwise from north.
   * @property {Property | number} [stRotation=0.0] A numeric property specifying the rotation of the ellipse texture counter-clockwise from north.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between points on the ellipse.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the ellipse is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the ellipse.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the ellipse is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | number} [numberOfVerticalLines=16] A numeric Property specifying the number of vertical lines to draw along the perimeter for the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the ellipse casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this ellipse will be displayed.
   * @property {Property | ClassificationType} [classificationType=ClassificationType.BOTH] An enum Property specifying whether this ellipse will classify terrain, 3D Tiles, or both when on the ground.
   * @property {ConstantProperty | number} [zIndex=0] A property specifying the zIndex of the Ellipse.  Used for ordering ground geometry.  Only has an effect if the ellipse is constant and neither height or exturdedHeight are specified.
   */

  /**
   * Describes an ellipse defined by a center point and semi-major and semi-minor axes.
   * The ellipse conforms to the curvature of the globe and can be placed on the surface or
   * at altitude and can optionally be extruded into a volume.
   * The center point is determined by the containing {@link Entity}.
   *
   * @alias EllipseGraphics
   * @constructor
   *
   * @param {EllipseGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Circles and Ellipses.html|Cesium Sandcastle Circles and Ellipses Demo}
   */
  function EllipseGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._semiMajorAxis = undefined;
    this._semiMajorAxisSubscription = undefined;
    this._semiMinorAxis = undefined;
    this._semiMinorAxisSubscription = undefined;
    this._height = undefined;
    this._heightSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._extrudedHeight = undefined;
    this._extrudedHeightSubscription = undefined;
    this._extrudedHeightReference = undefined;
    this._extrudedHeightReferenceSubscription = undefined;
    this._rotation = undefined;
    this._rotationSubscription = undefined;
    this._stRotation = undefined;
    this._stRotationSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._numberOfVerticalLines = undefined;
    this._numberOfVerticalLinesSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._classificationType = undefined;
    this._classificationTypeSubscription = undefined;
    this._zIndex = undefined;
    this._zIndexSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(EllipseGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof EllipseGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the ellipse.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the numeric Property specifying the semi-major axis.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     */
    semiMajorAxis: createPropertyDescriptor("semiMajorAxis"),

    /**
     * Gets or sets the numeric Property specifying the semi-minor axis.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     */
    semiMinorAxis: createPropertyDescriptor("semiMinorAxis"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the ellipse.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    height: createPropertyDescriptor("height"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the ellipse extrusion.
     * Setting this property creates volume starting at height and ending at this altitude.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     */
    extrudedHeight: createPropertyDescriptor("extrudedHeight"),

    /**
     * Gets or sets the Property specifying the extruded {@link HeightReference}.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    extrudedHeightReference: createPropertyDescriptor("extrudedHeightReference"),

    /**
     * Gets or sets the numeric property specifying the rotation of the ellipse clockwise from north.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    rotation: createPropertyDescriptor("rotation"),

    /**
     * Gets or sets the numeric property specifying the rotation of the ellipse texture counter-clockwise from north.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    stRotation: createPropertyDescriptor("stRotation"),

    /**
     * Gets or sets the numeric Property specifying the angular distance between points on the ellipse.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default {CesiumMath.RADIANS_PER_DEGREE}
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the boolean Property specifying whether the ellipse is filled with the provided material.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the ellipse.
     * @memberof EllipseGraphics.prototype
     * @type {MaterialProperty|undefined}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the ellipse is outlined.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Gets or sets the numeric Property specifying the number of vertical lines to draw along the perimeter for the outline.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default 16
     */
    numberOfVerticalLines: createPropertyDescriptor("numberOfVerticalLines"),

    /**
     * Get or sets the enum Property specifying whether the ellipse
     * casts or receives shadows from light sources.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this ellipse will be displayed.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the {@link ClassificationType} Property specifying whether this ellipse will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof EllipseGraphics.prototype
     * @type {Property|undefined}
     * @default ClassificationType.BOTH
     */
    classificationType: createPropertyDescriptor("classificationType"),

    /**
     * Gets or sets the zIndex Property specifying the ellipse ordering.  Only has an effect if the ellipse is constant and neither height or extrudedHeight are specified
     * @memberof EllipseGraphics.prototype
     * @type {ConstantProperty|undefined}
     * @default 0
     */
    zIndex: createPropertyDescriptor("zIndex"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {EllipseGraphics} [result] The object onto which to store the result.
   * @returns {EllipseGraphics} The modified result parameter or a new instance if one was not provided.
   */
  EllipseGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new EllipseGraphics(this);
    }
    result.show = this.show;
    result.semiMajorAxis = this.semiMajorAxis;
    result.semiMinorAxis = this.semiMinorAxis;
    result.height = this.height;
    result.heightReference = this.heightReference;
    result.extrudedHeight = this.extrudedHeight;
    result.extrudedHeightReference = this.extrudedHeightReference;
    result.rotation = this.rotation;
    result.stRotation = this.stRotation;
    result.granularity = this.granularity;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.numberOfVerticalLines = this.numberOfVerticalLines;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.classificationType = this.classificationType;
    result.zIndex = this.zIndex;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {EllipseGraphics} source The object to be merged into this object.
   */
  EllipseGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.semiMajorAxis = defaultValue(this.semiMajorAxis, source.semiMajorAxis);
    this.semiMinorAxis = defaultValue(this.semiMinorAxis, source.semiMinorAxis);
    this.height = defaultValue(this.height, source.height);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.extrudedHeight = defaultValue(
      this.extrudedHeight,
      source.extrudedHeight
    );
    this.extrudedHeightReference = defaultValue(
      this.extrudedHeightReference,
      source.extrudedHeightReference
    );
    this.rotation = defaultValue(this.rotation, source.rotation);
    this.stRotation = defaultValue(this.stRotation, source.stRotation);
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.numberOfVerticalLines = defaultValue(
      this.numberOfVerticalLines,
      source.numberOfVerticalLines
    );
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.classificationType = defaultValue(
      this.classificationType,
      source.classificationType
    );
    this.zIndex = defaultValue(this.zIndex, source.zIndex);
  };

  /**
   * @typedef {Object} EllipsoidGraphics.ConstructorOptions
   *
   * Initialization options for the EllipsoidGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the ellipsoid.
   * @property {Property | Cartesian3} [radii] A {@link Cartesian3} Property specifying the radii of the ellipsoid.
   * @property {Property | Cartesian3} [innerRadii] A {@link Cartesian3} Property specifying the inner radii of the ellipsoid.
   * @property {Property | number} [minimumClock=0.0] A Property specifying the minimum clock angle of the ellipsoid.
   * @property {Property | number} [maximumClock=2*PI] A Property specifying the maximum clock angle of the ellipsoid.
   * @property {Property | number} [minimumCone=0.0] A Property specifying the minimum cone angle of the ellipsoid.
   * @property {Property | number} [maximumCone=PI] A Property specifying the maximum cone angle of the ellipsoid.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height from the entity position is relative to.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the ellipsoid is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the ellipsoid.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the ellipsoid is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | number} [stackPartitions=64] A Property specifying the number of stacks.
   * @property {Property | number} [slicePartitions=64] A Property specifying the number of radial slices.
   * @property {Property | number} [subdivisions=128] A Property specifying the number of samples per outline ring, determining the granularity of the curvature.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the ellipsoid casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this ellipsoid will be displayed.
   */

  /**
   * Describe an ellipsoid or sphere.  The center position and orientation are determined by the containing {@link Entity}.
   *
   * @alias EllipsoidGraphics
   * @constructor
   *
   * @param {EllipsoidGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Spheres%20and%20Ellipsoids.html|Cesium Sandcastle Spheres and Ellipsoids Demo}
   */
  function EllipsoidGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._radii = undefined;
    this._radiiSubscription = undefined;
    this._innerRadii = undefined;
    this._innerRadiiSubscription = undefined;
    this._minimumClock = undefined;
    this._minimumClockSubscription = undefined;
    this._maximumClock = undefined;
    this._maximumClockSubscription = undefined;
    this._minimumCone = undefined;
    this._minimumConeSubscription = undefined;
    this._maximumCone = undefined;
    this._maximumConeSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._stackPartitions = undefined;
    this._stackPartitionsSubscription = undefined;
    this._slicePartitions = undefined;
    this._slicePartitionsSubscription = undefined;
    this._subdivisions = undefined;
    this._subdivisionsSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(EllipsoidGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof EllipsoidGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the {@link Cartesian3} {@link Property} specifying the radii of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     */
    radii: createPropertyDescriptor("radii"),

    /**
     * Gets or sets the {@link Cartesian3} {@link Property} specifying the inner radii of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default radii
     */
    innerRadii: createPropertyDescriptor("innerRadii"),

    /**
     * Gets or sets the Property specifying the minimum clock angle of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    minimumClock: createPropertyDescriptor("minimumClock"),

    /**
     * Gets or sets the Property specifying the maximum clock angle of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 2*PI
     */
    maximumClock: createPropertyDescriptor("maximumClock"),

    /**
     * Gets or sets the Property specifying the minimum cone angle of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    minimumCone: createPropertyDescriptor("minimumCone"),

    /**
     * Gets or sets the Property specifying the maximum cone angle of the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default PI
     */
    maximumCone: createPropertyDescriptor("maximumCone"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the boolean Property specifying whether the ellipsoid is filled with the provided material.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the ellipsoid.
     * @memberof EllipsoidGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the ellipsoid is outlined.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Gets or sets the Property specifying the number of stacks.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 64
     */
    stackPartitions: createPropertyDescriptor("stackPartitions"),

    /**
     * Gets or sets the Property specifying the number of radial slices per 360 degrees.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 64
     */
    slicePartitions: createPropertyDescriptor("slicePartitions"),

    /**
     * Gets or sets the Property specifying the number of samples per outline ring, determining the granularity of the curvature.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default 128
     */
    subdivisions: createPropertyDescriptor("subdivisions"),

    /**
     * Get or sets the enum Property specifying whether the ellipsoid
     * casts or receives shadows from light sources.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this ellipsoid will be displayed.
     * @memberof EllipsoidGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {EllipsoidGraphics} [result] The object onto which to store the result.
   * @returns {EllipsoidGraphics} The modified result parameter or a new instance if one was not provided.
   */
  EllipsoidGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new EllipsoidGraphics(this);
    }
    result.show = this.show;
    result.radii = this.radii;
    result.innerRadii = this.innerRadii;
    result.minimumClock = this.minimumClock;
    result.maximumClock = this.maximumClock;
    result.minimumCone = this.minimumCone;
    result.maximumCone = this.maximumCone;
    result.heightReference = this.heightReference;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.stackPartitions = this.stackPartitions;
    result.slicePartitions = this.slicePartitions;
    result.subdivisions = this.subdivisions;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {EllipsoidGraphics} source The object to be merged into this object.
   */
  EllipsoidGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.radii = defaultValue(this.radii, source.radii);
    this.innerRadii = defaultValue(this.innerRadii, source.innerRadii);
    this.minimumClock = defaultValue(this.minimumClock, source.minimumClock);
    this.maximumClock = defaultValue(this.maximumClock, source.maximumClock);
    this.minimumCone = defaultValue(this.minimumCone, source.minimumCone);
    this.maximumCone = defaultValue(this.maximumCone, source.maximumCone);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.stackPartitions = defaultValue(
      this.stackPartitions,
      source.stackPartitions
    );
    this.slicePartitions = defaultValue(
      this.slicePartitions,
      source.slicePartitions
    );
    this.subdivisions = defaultValue(this.subdivisions, source.subdivisions);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  /**
   * @typedef {Object} LabelGraphics.ConstructorOptions
   *
   * Initialization options for the LabelGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the label.
   * @property {Property | string} [text] A Property specifying the text. Explicit newlines '\n' are supported.
   * @property {Property | string} [font='30px sans-serif'] A Property specifying the CSS font.
   * @property {Property | LabelStyle} [style=LabelStyle.FILL] A Property specifying the {@link LabelStyle}.
   * @property {Property | number} [scale=1.0] A numeric Property specifying the scale to apply to the text.
   * @property {Property | boolean} [showBackground=false] A boolean Property specifying the visibility of the background behind the label.
   * @property {Property | Color} [backgroundColor=new Color(0.165, 0.165, 0.165, 0.8)] A Property specifying the background {@link Color}.
   * @property {Property | Cartesian2} [backgroundPadding=new Cartesian2(7, 5)] A {@link Cartesian2} Property specifying the horizontal and vertical background padding in pixels.
   * @property {Property | Cartesian2} [pixelOffset=Cartesian2.ZERO] A {@link Cartesian2} Property specifying the pixel offset.
   * @property {Property | Cartesian3} [eyeOffset=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the eye offset.
   * @property {Property | HorizontalOrigin} [horizontalOrigin=HorizontalOrigin.CENTER] A Property specifying the {@link HorizontalOrigin}.
   * @property {Property | VerticalOrigin} [verticalOrigin=VerticalOrigin.CENTER] A Property specifying the {@link VerticalOrigin}.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | Color} [fillColor=Color.WHITE] A Property specifying the fill {@link Color}.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the outline {@link Color}.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the outline width.
   * @property {Property | NearFarScalar} [translucencyByDistance] A {@link NearFarScalar} Property used to set translucency based on distance from the camera.
   * @property {Property | NearFarScalar} [pixelOffsetScaleByDistance] A {@link NearFarScalar} Property used to set pixelOffset based on distance from the camera.
   * @property {Property | NearFarScalar} [scaleByDistance] A {@link NearFarScalar} Property used to set scale based on distance from the camera.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this label will be displayed.
   * @property {Property | number} [disableDepthTestDistance] A Property specifying the distance from the camera at which to disable the depth test to.
   */

  /**
   * Describes a two dimensional label located at the position of the containing {@link Entity}.
   * <p>
   * <div align='center'>
   * <img src='Images/Label.png' width='400' height='300' /><br />
   * Example labels
   * </div>
   * </p>
   *
   * @alias LabelGraphics
   * @constructor
   *
   * @param {LabelGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Labels.html|Cesium Sandcastle Labels Demo}
   */
  function LabelGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._text = undefined;
    this._textSubscription = undefined;
    this._font = undefined;
    this._fontSubscription = undefined;
    this._style = undefined;
    this._styleSubscription = undefined;
    this._scale = undefined;
    this._scaleSubscription = undefined;
    this._showBackground = undefined;
    this._showBackgroundSubscription = undefined;
    this._backgroundColor = undefined;
    this._backgroundColorSubscription = undefined;
    this._backgroundPadding = undefined;
    this._backgroundPaddingSubscription = undefined;
    this._pixelOffset = undefined;
    this._pixelOffsetSubscription = undefined;
    this._eyeOffset = undefined;
    this._eyeOffsetSubscription = undefined;
    this._horizontalOrigin = undefined;
    this._horizontalOriginSubscription = undefined;
    this._verticalOrigin = undefined;
    this._verticalOriginSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._fillColor = undefined;
    this._fillColorSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._translucencyByDistance = undefined;
    this._translucencyByDistanceSubscription = undefined;
    this._pixelOffsetScaleByDistance = undefined;
    this._pixelOffsetScaleByDistanceSubscription = undefined;
    this._scaleByDistance = undefined;
    this._scaleByDistanceSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._disableDepthTestDistance = undefined;
    this._disableDepthTestDistanceSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(LabelGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof LabelGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the label.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the string Property specifying the text of the label.
     * Explicit newlines '\n' are supported.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    text: createPropertyDescriptor("text"),

    /**
     * Gets or sets the string Property specifying the font in CSS syntax.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/CSS/font|CSS font on MDN}
     */
    font: createPropertyDescriptor("font"),

    /**
     * Gets or sets the Property specifying the {@link LabelStyle}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    style: createPropertyDescriptor("style"),

    /**
     * Gets or sets the numeric Property specifying the uniform scale to apply to the image.
     * A scale greater than <code>1.0</code> enlarges the label while a scale less than <code>1.0</code> shrinks it.
     * <p>
     * <div align='center'>
     * <img src='Images/Label.setScale.png' width='400' height='300' /><br/>
     * From left to right in the above image, the scales are <code>0.5</code>, <code>1.0</code>,
     * and <code>2.0</code>.
     * </div>
     * </p>
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    scale: createPropertyDescriptor("scale"),

    /**
     * Gets or sets the boolean Property specifying the visibility of the background behind the label.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    showBackground: createPropertyDescriptor("showBackground"),

    /**
     * Gets or sets the Property specifying the background {@link Color}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default new Color(0.165, 0.165, 0.165, 0.8)
     */
    backgroundColor: createPropertyDescriptor("backgroundColor"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the label's horizontal and vertical
     * background padding in pixels.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default new Cartesian2(7, 5)
     */
    backgroundPadding: createPropertyDescriptor("backgroundPadding"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the label's pixel offset in screen space
     * from the origin of this label.  This is commonly used to align multiple labels and labels at
     * the same position, e.g., an image and text.  The screen space origin is the top, left corner of the
     * canvas; <code>x</code> increases from left to right, and <code>y</code> increases from top to bottom.
     * <p>
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><code>default</code><br/><img src='Images/Label.setPixelOffset.default.png' width='250' height='188' /></td>
     * <td align='center'><code>l.pixeloffset = new Cartesian2(25, 75);</code><br/><img src='Images/Label.setPixelOffset.x50y-25.png' width='250' height='188' /></td>
     * </tr></table>
     * The label's origin is indicated by the yellow point.
     * </div>
     * </p>
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default Cartesian2.ZERO
     */
    pixelOffset: createPropertyDescriptor("pixelOffset"),

    /**
     * Gets or sets the {@link Cartesian3} Property specifying the label's offset in eye coordinates.
     * Eye coordinates is a left-handed coordinate system, where <code>x</code> points towards the viewer's
     * right, <code>y</code> points up, and <code>z</code> points into the screen.
     * <p>
     * An eye offset is commonly used to arrange multiple labels or objects at the same position, e.g., to
     * arrange a label above its corresponding 3D model.
     * </p>
     * Below, the label is positioned at the center of the Earth but an eye offset makes it always
     * appear on top of the Earth regardless of the viewer's or Earth's orientation.
     * <p>
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.one.png' width='250' height='188' /></td>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.two.png' width='250' height='188' /></td>
     * </tr></table>
     * <code>l.eyeOffset = new Cartesian3(0.0, 8000000.0, 0.0);</code><br /><br />
     * </div>
     * </p>
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default Cartesian3.ZERO
     */
    eyeOffset: createPropertyDescriptor("eyeOffset"),

    /**
     * Gets or sets the Property specifying the {@link HorizontalOrigin}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    horizontalOrigin: createPropertyDescriptor("horizontalOrigin"),

    /**
     * Gets or sets the Property specifying the {@link VerticalOrigin}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    verticalOrigin: createPropertyDescriptor("verticalOrigin"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the Property specifying the fill {@link Color}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    fillColor: createPropertyDescriptor("fillColor"),

    /**
     * Gets or sets the Property specifying the outline {@link Color}.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the outline width.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Gets or sets {@link NearFarScalar} Property specifying the translucency of the label based on the distance from the camera.
     * A label's translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the label's translucency remains clamped to the nearest bound.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    translucencyByDistance: createPropertyDescriptor("translucencyByDistance"),

    /**
     * Gets or sets {@link NearFarScalar} Property specifying the pixel offset of the label based on the distance from the camera.
     * A label's pixel offset will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the label's pixel offset remains clamped to the nearest bound.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    pixelOffsetScaleByDistance: createPropertyDescriptor(
      "pixelOffsetScaleByDistance"
    ),

    /**
     * Gets or sets near and far scaling properties of a Label based on the label's distance from the camera.
     * A label's scale will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the label's scale remains clamped to the nearest bound.  If undefined,
     * scaleByDistance will be disabled.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    scaleByDistance: createPropertyDescriptor("scaleByDistance"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this label will be displayed.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
     * When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.
     * @memberof LabelGraphics.prototype
     * @type {Property|undefined}
     */
    disableDepthTestDistance: createPropertyDescriptor(
      "disableDepthTestDistance"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {LabelGraphics} [result] The object onto which to store the result.
   * @returns {LabelGraphics} The modified result parameter or a new instance if one was not provided.
   */
  LabelGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new LabelGraphics(this);
    }
    result.show = this.show;
    result.text = this.text;
    result.font = this.font;
    result.style = this.style;
    result.scale = this.scale;
    result.showBackground = this.showBackground;
    result.backgroundColor = this.backgroundColor;
    result.backgroundPadding = this.backgroundPadding;
    result.pixelOffset = this.pixelOffset;
    result.eyeOffset = this.eyeOffset;
    result.horizontalOrigin = this.horizontalOrigin;
    result.verticalOrigin = this.verticalOrigin;
    result.heightReference = this.heightReference;
    result.fillColor = this.fillColor;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.translucencyByDistance = this.translucencyByDistance;
    result.pixelOffsetScaleByDistance = this.pixelOffsetScaleByDistance;
    result.scaleByDistance = this.scaleByDistance;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.disableDepthTestDistance = this.disableDepthTestDistance;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {LabelGraphics} source The object to be merged into this object.
   */
  LabelGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.text = defaultValue(this.text, source.text);
    this.font = defaultValue(this.font, source.font);
    this.style = defaultValue(this.style, source.style);
    this.scale = defaultValue(this.scale, source.scale);
    this.showBackground = defaultValue(
      this.showBackground,
      source.showBackground
    );
    this.backgroundColor = defaultValue(
      this.backgroundColor,
      source.backgroundColor
    );
    this.backgroundPadding = defaultValue(
      this.backgroundPadding,
      source.backgroundPadding
    );
    this.pixelOffset = defaultValue(this.pixelOffset, source.pixelOffset);
    this.eyeOffset = defaultValue(this.eyeOffset, source.eyeOffset);
    this.horizontalOrigin = defaultValue(
      this.horizontalOrigin,
      source.horizontalOrigin
    );
    this.verticalOrigin = defaultValue(
      this.verticalOrigin,
      source.verticalOrigin
    );
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.fillColor = defaultValue(this.fillColor, source.fillColor);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.translucencyByDistance = defaultValue(
      this.translucencyByDistance,
      source.translucencyByDistance
    );
    this.pixelOffsetScaleByDistance = defaultValue(
      this.pixelOffsetScaleByDistance,
      source.pixelOffsetScaleByDistance
    );
    this.scaleByDistance = defaultValue(
      this.scaleByDistance,
      source.scaleByDistance
    );
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.disableDepthTestDistance = defaultValue(
      this.disableDepthTestDistance,
      source.disableDepthTestDistance
    );
  };

  var defaultNodeTransformation = new TranslationRotationScale();

  /**
   * A {@link Property} that produces {@link TranslationRotationScale} data.
   * @alias NodeTransformationProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|Cartesian3} [options.translation=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the (x, y, z) translation to apply to the node.
   * @param {Property|Quaternion} [options.rotation=Quaternion.IDENTITY] A {@link Quaternion} Property specifying the (x, y, z, w) rotation to apply to the node.
   * @param {Property|Cartesian3} [options.scale=new Cartesian3(1.0, 1.0, 1.0)] A {@link Cartesian3} Property specifying the (x, y, z) scaling to apply to the node.
   */
  function NodeTransformationProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._translation = undefined;
    this._translationSubscription = undefined;
    this._rotation = undefined;
    this._rotationSubscription = undefined;
    this._scale = undefined;
    this._scaleSubscription = undefined;

    this.translation = options.translation;
    this.rotation = options.rotation;
    this.scale = options.scale;
  }

  Object.defineProperties(NodeTransformationProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof NodeTransformationProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._translation) &&
          Property.isConstant(this._rotation) &&
          Property.isConstant(this._scale)
        );
      },
    },

    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof NodeTransformationProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the {@link Cartesian3} Property specifying the (x, y, z) translation to apply to the node.
     * @memberof NodeTransformationProperty.prototype
     * @type {Property|undefined}
     * @default Cartesian3.ZERO
     */
    translation: createPropertyDescriptor("translation"),

    /**
     * Gets or sets the {@link Quaternion} Property specifying the (x, y, z, w) rotation to apply to the node.
     * @memberof NodeTransformationProperty.prototype
     * @type {Property|undefined}
     * @default Quaternion.IDENTITY
     */
    rotation: createPropertyDescriptor("rotation"),

    /**
     * Gets or sets the {@link Cartesian3} Property specifying the (x, y, z) scaling to apply to the node.
     * @memberof NodeTransformationProperty.prototype
     * @type {Property|undefined}
     * @default new Cartesian3(1.0, 1.0, 1.0)
     */
    scale: createPropertyDescriptor("scale"),
  });

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {TranslationRotationScale} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {TranslationRotationScale} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  NodeTransformationProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = new TranslationRotationScale();
    }

    result.translation = Property.getValueOrClonedDefault(
      this._translation,
      time,
      defaultNodeTransformation.translation,
      result.translation
    );
    result.rotation = Property.getValueOrClonedDefault(
      this._rotation,
      time,
      defaultNodeTransformation.rotation,
      result.rotation
    );
    result.scale = Property.getValueOrClonedDefault(
      this._scale,
      time,
      defaultNodeTransformation.scale,
      result.scale
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  NodeTransformationProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof NodeTransformationProperty &&
        Property.equals(this._translation, other._translation) &&
        Property.equals(this._rotation, other._rotation) &&
        Property.equals(this._scale, other._scale))
    );
  };

  /**
   * A {@link Property} whose value is a key-value mapping of property names to the computed value of other properties.
   *
   * @alias PropertyBag
   * @constructor
   * @implements {DictionaryLike}
   *
   * @param {Object} [value] An object, containing key-value mapping of property names to properties.
   * @param {Function} [createPropertyCallback] A function that will be called when the value of any of the properties in value are not a Property.
   */
  function PropertyBag(value, createPropertyCallback) {
    this._propertyNames = [];
    this._definitionChanged = new Event();

    if (defined(value)) {
      this.merge(value, createPropertyCallback);
    }
  }

  Object.defineProperties(PropertyBag.prototype, {
    /**
     * Gets the names of all properties registered on this instance.
     * @memberof PropertyBag.prototype
     * @type {Array}
     */
    propertyNames: {
      get: function () {
        return this._propertyNames;
      },
    },
    /**
     * Gets a value indicating if this property is constant.  This property
     * is considered constant if all property items in this object are constant.
     * @memberof PropertyBag.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        var propertyNames = this._propertyNames;
        for (var i = 0, len = propertyNames.length; i < len; i++) {
          if (!Property.isConstant(this[propertyNames[i]])) {
            return false;
          }
        }
        return true;
      },
    },
    /**
     * Gets the event that is raised whenever the set of properties contained in this
     * object changes, or one of the properties itself changes.
     *
     * @memberof PropertyBag.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
  });

  /**
   * Determines if this object has defined a property with the given name.
   *
   * @param {String} propertyName The name of the property to check for.
   *
   * @returns {Boolean} True if this object has defined a property with the given name, false otherwise.
   */
  PropertyBag.prototype.hasProperty = function (propertyName) {
    return this._propertyNames.indexOf(propertyName) !== -1;
  };

  function createConstantProperty$1(value) {
    return new ConstantProperty(value);
  }

  /**
   * Adds a property to this object.
   *
   * @param {String} propertyName The name of the property to add.
   * @param {*} [value] The value of the new property, if provided.
   * @param {Function} [createPropertyCallback] A function that will be called when the value of this new property is set to a value that is not a Property.
   *
   * @exception {DeveloperError} "propertyName" is already a registered property.
   */
  PropertyBag.prototype.addProperty = function (
    propertyName,
    value,
    createPropertyCallback
  ) {
    var propertyNames = this._propertyNames;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(propertyName)) {
      throw new DeveloperError("propertyName is required.");
    }
    if (propertyNames.indexOf(propertyName) !== -1) {
      throw new DeveloperError(
        propertyName + " is already a registered property."
      );
    }
    //>>includeEnd('debug');

    propertyNames.push(propertyName);
    Object.defineProperty(
      this,
      propertyName,
      createPropertyDescriptor(
        propertyName,
        true,
        defaultValue(createPropertyCallback, createConstantProperty$1)
      )
    );

    if (defined(value)) {
      this[propertyName] = value;
    }

    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Removed a property previously added with addProperty.
   *
   * @param {String} propertyName The name of the property to remove.
   *
   * @exception {DeveloperError} "propertyName" is not a registered property.
   */
  PropertyBag.prototype.removeProperty = function (propertyName) {
    var propertyNames = this._propertyNames;
    var index = propertyNames.indexOf(propertyName);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(propertyName)) {
      throw new DeveloperError("propertyName is required.");
    }
    if (index === -1) {
      throw new DeveloperError(propertyName + " is not a registered property.");
    }
    //>>includeEnd('debug');

    this._propertyNames.splice(index, 1);
    delete this[propertyName];

    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Gets the value of this property.  Each contained property will be evaluated at the given time, and the overall
   * result will be an object, mapping property names to those values.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * Note that any properties in result which are not part of this PropertyBag will be left as-is.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PropertyBag.prototype.getValue = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = {};
    }

    var propertyNames = this._propertyNames;
    for (var i = 0, len = propertyNames.length; i < len; i++) {
      var propertyName = propertyNames[i];
      result[propertyName] = Property.getValueOrUndefined(
        this[propertyName],
        time,
        result[propertyName]
      );
    }
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {Object} source The object to be merged into this object.
   * @param {Function} [createPropertyCallback] A function that will be called when the value of any of the properties in value are not a Property.
   */
  PropertyBag.prototype.merge = function (source, createPropertyCallback) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    var propertyNames = this._propertyNames;
    var sourcePropertyNames = defined(source._propertyNames)
      ? source._propertyNames
      : Object.keys(source);
    for (var i = 0, len = sourcePropertyNames.length; i < len; i++) {
      var name = sourcePropertyNames[i];

      var targetProperty = this[name];
      var sourceProperty = source[name];

      //Custom properties that are registered on the source must also be added to this.
      if (targetProperty === undefined && propertyNames.indexOf(name) === -1) {
        this.addProperty(name, undefined, createPropertyCallback);
      }

      if (sourceProperty !== undefined) {
        if (targetProperty !== undefined) {
          if (defined(targetProperty) && defined(targetProperty.merge)) {
            targetProperty.merge(sourceProperty);
          }
        } else if (
          defined(sourceProperty) &&
          defined(sourceProperty.merge) &&
          defined(sourceProperty.clone)
        ) {
          this[name] = sourceProperty.clone();
        } else {
          this[name] = sourceProperty;
        }
      }
    }
  };

  function propertiesEqual(a, b) {
    var aPropertyNames = a._propertyNames;
    var bPropertyNames = b._propertyNames;

    var len = aPropertyNames.length;
    if (len !== bPropertyNames.length) {
      return false;
    }

    for (var aIndex = 0; aIndex < len; ++aIndex) {
      var name = aPropertyNames[aIndex];
      var bIndex = bPropertyNames.indexOf(name);
      if (bIndex === -1) {
        return false;
      }
      if (!Property.equals(a[name], b[name])) {
        return false;
      }
    }
    return true;
  }

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PropertyBag.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof PropertyBag && //
        propertiesEqual(this, other))
    );
  };

  function createNodeTransformationProperty(value) {
    return new NodeTransformationProperty(value);
  }

  function createNodeTransformationPropertyBag(value) {
    return new PropertyBag(value, createNodeTransformationProperty);
  }

  function createArticulationStagePropertyBag(value) {
    return new PropertyBag(value);
  }

  /**
   * @typedef {Object} ModelGraphics.ConstructorOptions
   *
   * Initialization options for the ModelGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the model.
   * @property {Property | string | Resource} [uri] A string or Resource Property specifying the URI of the glTF asset.
   * @property {Property | number} [scale=1.0] A numeric Property specifying a uniform linear scale.
   * @property {Property | number} [minimumPixelSize=0.0] A numeric Property specifying the approximate minimum pixel size of the model regardless of zoom.
   * @property {Property | number} [maximumScale] The maximum scale size of a model. An upper limit for minimumPixelSize.
   * @property {Property | boolean} [incrementallyLoadTextures=true] Determine if textures may continue to stream in after the model is loaded.
   * @property {Property | boolean} [runAnimations=true] A boolean Property specifying if glTF animations specified in the model should be started.
   * @property {Property | boolean} [clampAnimations=true] A boolean Property specifying if glTF animations should hold the last pose for time durations with no keyframes.
   * @property {Property | ShadowMode} [shadows=ShadowMode.ENABLED] An enum Property specifying whether the model casts or receives shadows from light sources.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | Color} [silhouetteColor=Color.RED] A Property specifying the {@link Color} of the silhouette.
   * @property {Property | number} [silhouetteSize=0.0] A numeric Property specifying the size of the silhouette in pixels.
   * @property {Property | Color} [color=Color.WHITE] A Property specifying the {@link Color} that blends with the model's rendered color.
   * @property {Property | ColorBlendMode} [colorBlendMode=ColorBlendMode.HIGHLIGHT] An enum Property specifying how the color blends with the model.
   * @property {Property | number} [colorBlendAmount=0.5] A numeric Property specifying the color strength when the <code>colorBlendMode</code> is <code>MIX</code>. A value of 0.0 results in the model's rendered color while a value of 1.0 results in a solid color, with any value in-between resulting in a mix of the two.
   * @property {Property | Cartesian2} [imageBasedLightingFactor=new Cartesian2(1.0, 1.0)] A property specifying the contribution from diffuse and specular image-based lighting.
   * @property {Property | Color} [lightColor] A property specifying the light color when shading the model. When <code>undefined</code> the scene's light color is used instead.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this model will be displayed.
   * @property {PropertyBag | Object.<string, TranslationRotationScale>} [nodeTransformations] An object, where keys are names of nodes, and values are {@link TranslationRotationScale} Properties describing the transformation to apply to that node. The transformation is applied after the node's existing transformation as specified in the glTF, and does not replace the node's existing transformation.
   * @property {PropertyBag | Object.<string, number>} [articulations] An object, where keys are composed of an articulation name, a single space, and a stage name, and the values are numeric properties.
   * @property {Property | ClippingPlaneCollection} [clippingPlanes] A property specifying the {@link ClippingPlaneCollection} used to selectively disable rendering the model.
   */

  /**
   * A 3D model based on {@link https://github.com/KhronosGroup/glTF|glTF}, the runtime asset format for WebGL, OpenGL ES, and OpenGL.
   * The position and orientation of the model is determined by the containing {@link Entity}.
   * <p>
   * Cesium includes support for glTF geometry, materials, animations, and skinning.
   * Cameras and lights are not currently supported.
   * </p>
   *
   * @alias ModelGraphics
   * @constructor
   *
   * @param {ModelGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see {@link https://cesium.com/docs/tutorials/3d-models/|3D Models Tutorial}
   * @demo {@link https://sandcastle.cesium.com/index.html?src=3D%20Models.html|Cesium Sandcastle 3D Models Demo}
   */
  function ModelGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._uri = undefined;
    this._uriSubscription = undefined;
    this._scale = undefined;
    this._scaleSubscription = undefined;
    this._minimumPixelSize = undefined;
    this._minimumPixelSizeSubscription = undefined;
    this._maximumScale = undefined;
    this._maximumScaleSubscription = undefined;
    this._incrementallyLoadTextures = undefined;
    this._incrementallyLoadTexturesSubscription = undefined;
    this._runAnimations = undefined;
    this._runAnimationsSubscription = undefined;
    this._clampAnimations = undefined;
    this._clampAnimationsSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._silhouetteColor = undefined;
    this._silhouetteColorSubscription = undefined;
    this._silhouetteSize = undefined;
    this._silhouetteSizeSubscription = undefined;
    this._color = undefined;
    this._colorSubscription = undefined;
    this._colorBlendMode = undefined;
    this._colorBlendModeSubscription = undefined;
    this._colorBlendAmount = undefined;
    this._colorBlendAmountSubscription = undefined;
    this._imageBasedLightingFactor = undefined;
    this._imageBasedLightingFactorSubscription = undefined;
    this._lightColor = undefined;
    this._lightColorSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._nodeTransformations = undefined;
    this._nodeTransformationsSubscription = undefined;
    this._articulations = undefined;
    this._articulationsSubscription = undefined;
    this._clippingPlanes = undefined;
    this._clippingPlanesSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(ModelGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof ModelGraphics.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the model.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the string Property specifying the URI of the glTF asset.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     */
    uri: createPropertyDescriptor("uri"),

    /**
     * Gets or sets the numeric Property specifying a uniform linear scale
     * for this model. Values greater than 1.0 increase the size of the model while
     * values less than 1.0 decrease it.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    scale: createPropertyDescriptor("scale"),

    /**
     * Gets or sets the numeric Property specifying the approximate minimum
     * pixel size of the model regardless of zoom. This can be used to ensure that
     * a model is visible even when the viewer zooms out.  When <code>0.0</code>,
     * no minimum size is enforced.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    minimumPixelSize: createPropertyDescriptor("minimumPixelSize"),

    /**
     * Gets or sets the numeric Property specifying the maximum scale
     * size of a model. This property is used as an upper limit for
     * {@link ModelGraphics#minimumPixelSize}.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     */
    maximumScale: createPropertyDescriptor("maximumScale"),

    /**
     * Get or sets the boolean Property specifying whether textures
     * may continue to stream in after the model is loaded.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     */
    incrementallyLoadTextures: createPropertyDescriptor(
      "incrementallyLoadTextures"
    ),

    /**
     * Gets or sets the boolean Property specifying if glTF animations should be run.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    runAnimations: createPropertyDescriptor("runAnimations"),

    /**
     * Gets or sets the boolean Property specifying if glTF animations should hold the last pose for time durations with no keyframes.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    clampAnimations: createPropertyDescriptor("clampAnimations"),

    /**
     * Get or sets the enum Property specifying whether the model
     * casts or receives shadows from light sources.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.ENABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the silhouette.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default Color.RED
     */
    silhouetteColor: createPropertyDescriptor("silhouetteColor"),

    /**
     * Gets or sets the numeric Property specifying the size of the silhouette in pixels.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    silhouetteSize: createPropertyDescriptor("silhouetteSize"),

    /**
     * Gets or sets the Property specifying the {@link Color} that blends with the model's rendered color.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the enum Property specifying how the color blends with the model.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default ColorBlendMode.HIGHLIGHT
     */
    colorBlendMode: createPropertyDescriptor("colorBlendMode"),

    /**
     * A numeric Property specifying the color strength when the <code>colorBlendMode</code> is MIX.
     * A value of 0.0 results in the model's rendered color while a value of 1.0 results in a solid color, with
     * any value in-between resulting in a mix of the two.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     * @default 0.5
     */
    colorBlendAmount: createPropertyDescriptor("colorBlendAmount"),

    /**
     * A property specifying the {@link Cartesian2} used to scale the diffuse and specular image-based lighting contribution to the final color.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     */
    imageBasedLightingFactor: createPropertyDescriptor(
      "imageBasedLightingFactor"
    ),

    /**
     * A property specifying the {@link Cartesian3} light color when shading the model. When <code>undefined</code> the scene's light color is used instead.
     * @memberOf ModelGraphics.prototype
     * @type {Property|undefined}
     */
    lightColor: createPropertyDescriptor("lightColor"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this model will be displayed.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the set of node transformations to apply to this model.  This is represented as an {@link PropertyBag}, where keys are
     * names of nodes, and values are {@link TranslationRotationScale} Properties describing the transformation to apply to that node.
     * The transformation is applied after the node's existing transformation as specified in the glTF, and does not replace the node's existing transformation.
     * @memberof ModelGraphics.prototype
     * @type {PropertyBag}
     */
    nodeTransformations: createPropertyDescriptor(
      "nodeTransformations",
      undefined,
      createNodeTransformationPropertyBag
    ),

    /**
     * Gets or sets the set of articulation values to apply to this model.  This is represented as an {@link PropertyBag}, where keys are
     * composed as the name of the articulation, a single space, and the name of the stage.
     * @memberof ModelGraphics.prototype
     * @type {PropertyBag}
     */
    articulations: createPropertyDescriptor(
      "articulations",
      undefined,
      createArticulationStagePropertyBag
    ),

    /**
     * A property specifying the {@link ClippingPlaneCollection} used to selectively disable rendering the model.
     * @memberof ModelGraphics.prototype
     * @type {Property|undefined}
     */
    clippingPlanes: createPropertyDescriptor("clippingPlanes"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {ModelGraphics} [result] The object onto which to store the result.
   * @returns {ModelGraphics} The modified result parameter or a new instance if one was not provided.
   */
  ModelGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new ModelGraphics(this);
    }
    result.show = this.show;
    result.uri = this.uri;
    result.scale = this.scale;
    result.minimumPixelSize = this.minimumPixelSize;
    result.maximumScale = this.maximumScale;
    result.incrementallyLoadTextures = this.incrementallyLoadTextures;
    result.runAnimations = this.runAnimations;
    result.clampAnimations = this.clampAnimations;
    result.heightReference = this._heightReference;
    result.silhouetteColor = this.silhouetteColor;
    result.silhouetteSize = this.silhouetteSize;
    result.color = this.color;
    result.colorBlendMode = this.colorBlendMode;
    result.colorBlendAmount = this.colorBlendAmount;
    result.imageBasedLightingFactor = this.imageBasedLightingFactor;
    result.lightColor = this.lightColor;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.nodeTransformations = this.nodeTransformations;
    result.articulations = this.articulations;
    result.clippingPlanes = this.clippingPlanes;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {ModelGraphics} source The object to be merged into this object.
   */
  ModelGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.uri = defaultValue(this.uri, source.uri);
    this.scale = defaultValue(this.scale, source.scale);
    this.minimumPixelSize = defaultValue(
      this.minimumPixelSize,
      source.minimumPixelSize
    );
    this.maximumScale = defaultValue(this.maximumScale, source.maximumScale);
    this.incrementallyLoadTextures = defaultValue(
      this.incrementallyLoadTextures,
      source.incrementallyLoadTextures
    );
    this.runAnimations = defaultValue(this.runAnimations, source.runAnimations);
    this.clampAnimations = defaultValue(
      this.clampAnimations,
      source.clampAnimations
    );
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.silhouetteColor = defaultValue(
      this.silhouetteColor,
      source.silhouetteColor
    );
    this.silhouetteSize = defaultValue(
      this.silhouetteSize,
      source.silhouetteSize
    );
    this.color = defaultValue(this.color, source.color);
    this.colorBlendMode = defaultValue(
      this.colorBlendMode,
      source.colorBlendMode
    );
    this.colorBlendAmount = defaultValue(
      this.colorBlendAmount,
      source.colorBlendAmount
    );
    this.imageBasedLightingFactor = defaultValue(
      this.imageBasedLightingFactor,
      source.imageBasedLightingFactor
    );
    this.lightColor = defaultValue(this.lightColor, source.lightColor);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.clippingPlanes = defaultValue(
      this.clippingPlanes,
      source.clippingPlanes
    );

    var sourceNodeTransformations = source.nodeTransformations;
    if (defined(sourceNodeTransformations)) {
      var targetNodeTransformations = this.nodeTransformations;
      if (defined(targetNodeTransformations)) {
        targetNodeTransformations.merge(sourceNodeTransformations);
      } else {
        this.nodeTransformations = new PropertyBag(
          sourceNodeTransformations,
          createNodeTransformationProperty
        );
      }
    }

    var sourceArticulations = source.articulations;
    if (defined(sourceArticulations)) {
      var targetArticulations = this.articulations;
      if (defined(targetArticulations)) {
        targetArticulations.merge(sourceArticulations);
      } else {
        this.articulations = new PropertyBag(sourceArticulations);
      }
    }
  };

  /**
   * @typedef {Object} Cesium3DTilesetGraphics.ConstructorOptions
   *
   * Initialization options for the Cesium3DTilesetGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the tileset.
   * @property {Property | string | Resource} [uri] A string or Resource Property specifying the URI of the tileset.
   * @property {Property | number} [maximumScreenSpaceError] A number or Property specifying the maximum screen space error used to drive level of detail refinement.
   */

  /**
   * A 3D Tiles tileset represented by an {@link Entity}.
   * The tileset modelMatrix is determined by the containing Entity position and orientation
   * or is left unset if position is undefined.
   *
   * @alias Cesium3DTilesetGraphics
   * @constructor
   *
   * @param {Cesium3DTilesetGraphics.ConstructorOptions} [options] Object describing initialization options
   */
  function Cesium3DTilesetGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._uri = undefined;
    this._uriSubscription = undefined;
    this._maximumScreenSpaceError = undefined;
    this._maximumScreenSpaceErrorSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(Cesium3DTilesetGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof Cesium3DTilesetGraphics.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the model.
     * @memberof Cesium3DTilesetGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the string Property specifying the URI of the glTF asset.
     * @memberof Cesium3DTilesetGraphics.prototype
     * @type {Property|undefined}
     */
    uri: createPropertyDescriptor("uri"),

    /**
     * Gets or sets the maximum screen space error used to drive level of detail refinement.
     * @memberof Cesium3DTilesetGraphics.prototype
     * @type {Property|undefined}
     */
    maximumScreenSpaceError: createPropertyDescriptor("maximumScreenSpaceError"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {Cesium3DTilesetGraphics} [result] The object onto which to store the result.
   * @returns {Cesium3DTilesetGraphics} The modified result parameter or a new instance if one was not provided.
   */
  Cesium3DTilesetGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new Cesium3DTilesetGraphics(this);
    }
    result.show = this.show;
    result.uri = this.uri;
    result.maximumScreenSpaceError = this.maximumScreenSpaceError;

    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {Cesium3DTilesetGraphics} source The object to be merged into this object.
   */
  Cesium3DTilesetGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.uri = defaultValue(this.uri, source.uri);
    this.maximumScreenSpaceError = defaultValue(
      this.maximumScreenSpaceError,
      source.maximumScreenSpaceError
    );
  };

  /**
   * @typedef {Object} PathGraphics.ConstructorOptions
   *
   * Initialization options for the PathGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the path.
   * @property {Property | number} [leadTime] A Property specifying the number of seconds in front the object to show.
   * @property {Property | number} [trailTime] A Property specifying the number of seconds behind of the object to show.
   * @property {Property | number} [width=1.0] A numeric Property specifying the width in pixels.
   * @property {Property | number} [resolution=60] A numeric Property specifying the maximum number of seconds to step when sampling the position.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to draw the path.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this path will be displayed.
   */

  /**
   * Describes a polyline defined as the path made by an {@link Entity} as it moves over time.
   *
   * @alias PathGraphics
   * @constructor
   *
   * @param {PathGraphics.ConstructorOptions} [options] Object describing initialization options
   */
  function PathGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._leadTime = undefined;
    this._leadTimeSubscription = undefined;
    this._trailTime = undefined;
    this._trailTimeSubscription = undefined;
    this._width = undefined;
    this._widthSubscription = undefined;
    this._resolution = undefined;
    this._resolutionSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(PathGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof PathGraphics.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the path.
     * @memberof PathGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the number of seconds in front of the object to show.
     * @memberof PathGraphics.prototype
     * @type {Property|undefined}
     */
    leadTime: createPropertyDescriptor("leadTime"),

    /**
     * Gets or sets the Property specifying the number of seconds behind the object to show.
     * @memberof PathGraphics.prototype
     * @type {Property|undefined}
     */
    trailTime: createPropertyDescriptor("trailTime"),

    /**
     * Gets or sets the numeric Property specifying the width in pixels.
     * @memberof PathGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    width: createPropertyDescriptor("width"),

    /**
     * Gets or sets the Property specifying the maximum number of seconds to step when sampling the position.
     * @memberof PathGraphics.prototype
     * @type {Property|undefined}
     * @default 60
     */
    resolution: createPropertyDescriptor("resolution"),

    /**
     * Gets or sets the Property specifying the material used to draw the path.
     * @memberof PathGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this path will be displayed.
     * @memberof PathGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {PathGraphics} [result] The object onto which to store the result.
   * @returns {PathGraphics} The modified result parameter or a new instance if one was not provided.
   */
  PathGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new PathGraphics(this);
    }
    result.show = this.show;
    result.leadTime = this.leadTime;
    result.trailTime = this.trailTime;
    result.width = this.width;
    result.resolution = this.resolution;
    result.material = this.material;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {PathGraphics} source The object to be merged into this object.
   */
  PathGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.leadTime = defaultValue(this.leadTime, source.leadTime);
    this.trailTime = defaultValue(this.trailTime, source.trailTime);
    this.width = defaultValue(this.width, source.width);
    this.resolution = defaultValue(this.resolution, source.resolution);
    this.material = defaultValue(this.material, source.material);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  /**
   * @typedef {Object} PlaneGraphics.ConstructorOptions
   *
   * Initialization options for the PlaneGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the plane.
   * @property {Property | Plane} [plane] A {@link Plane} Property specifying the normal and distance for the plane.
   * @property {Property | Cartesian2} [dimensions] A {@link Cartesian2} Property specifying the width and height of the plane.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the plane is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the plane.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the plane is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the plane casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this plane will be displayed.
   */

  /**
   * Describes a plane. The center position and orientation are determined by the containing {@link Entity}.
   *
   * @alias PlaneGraphics
   * @constructor
   *
   * @param {PlaneGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Plane.html|Cesium Sandcastle Plane Demo}
   */
  function PlaneGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._plane = undefined;
    this._planeSubscription = undefined;
    this._dimensions = undefined;
    this._dimensionsSubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(PlaneGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof PlaneGraphics.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the plane.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the {@link Plane} Property specifying the normal and distance of the plane.
     *
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     */
    plane: createPropertyDescriptor("plane"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the width and height of the plane.
     *
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     */
    dimensions: createPropertyDescriptor("dimensions"),

    /**
     * Gets or sets the boolean Property specifying whether the plane is filled with the provided material.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the material used to fill the plane.
     * @memberof PlaneGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the plane is outlined.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Get or sets the enum Property specifying whether the plane
     * casts or receives shadows from light sources.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this plane will be displayed.
     * @memberof PlaneGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {PlaneGraphics} [result] The object onto which to store the result.
   * @returns {PlaneGraphics} The modified result parameter or a new instance if one was not provided.
   */
  PlaneGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new PlaneGraphics(this);
    }
    result.show = this.show;
    result.plane = this.plane;
    result.dimensions = this.dimensions;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {PlaneGraphics} source The object to be merged into this object.
   */
  PlaneGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.plane = defaultValue(this.plane, source.plane);
    this.dimensions = defaultValue(this.dimensions, source.dimensions);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  /**
   * @typedef {Object} PointGraphics.ConstructorOptions
   *
   * Initialization options for the PointGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the point.
   * @property {Property | number} [pixelSize=1] A numeric Property specifying the size in pixels.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | Color} [color=Color.WHITE] A Property specifying the {@link Color} of the point.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=0] A numeric Property specifying the the outline width in pixels.
   * @property {Property | NearFarScalar} [scaleByDistance] A {@link NearFarScalar} Property used to scale the point based on distance.
   * @property {Property | NearFarScalar} [translucencyByDistance] A {@link NearFarScalar} Property used to set translucency based on distance from the camera.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this point will be displayed.
   * @property {Property | number} [disableDepthTestDistance] A Property specifying the distance from the camera at which to disable the depth test to.
   */

  /**
   * Describes a graphical point located at the position of the containing {@link Entity}.
   *
   * @alias PointGraphics
   * @constructor
   *
   * @param {PointGraphics.ConstructorOptions} [options] Object describing initialization options
   */
  function PointGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._pixelSize = undefined;
    this._pixelSizeSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._color = undefined;
    this._colorSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._scaleByDistance = undefined;
    this._scaleByDistanceSubscription = undefined;
    this._translucencyByDistance = undefined;
    this._translucencyByDistanceSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._disableDepthTestDistance = undefined;
    this._disableDepthTestDistanceSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(PointGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof PointGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the point.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the numeric Property specifying the size in pixels.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     * @default 1
     */
    pixelSize: createPropertyDescriptor("pixelSize"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the point.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the the outline width in pixels.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Gets or sets the {@link NearFarScalar} Property used to scale the point based on distance.
     * If undefined, a constant size is used.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     */
    scaleByDistance: createPropertyDescriptor("scaleByDistance"),

    /**
     * Gets or sets {@link NearFarScalar} Property specifying the translucency of the point based on the distance from the camera.
     * A point's translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the points's translucency remains clamped to the nearest bound.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     */
    translucencyByDistance: createPropertyDescriptor("translucencyByDistance"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this point will be displayed.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
     * When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.
     * @memberof PointGraphics.prototype
     * @type {Property|undefined}
     */
    disableDepthTestDistance: createPropertyDescriptor(
      "disableDepthTestDistance"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {PointGraphics} [result] The object onto which to store the result.
   * @returns {PointGraphics} The modified result parameter or a new instance if one was not provided.
   */
  PointGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new PointGraphics(this);
    }
    result.show = this.show;
    result.pixelSize = this.pixelSize;
    result.heightReference = this.heightReference;
    result.color = this.color;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.scaleByDistance = this.scaleByDistance;
    result.translucencyByDistance = this._translucencyByDistance;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.disableDepthTestDistance = this.disableDepthTestDistance;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {PointGraphics} source The object to be merged into this object.
   */
  PointGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.pixelSize = defaultValue(this.pixelSize, source.pixelSize);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.color = defaultValue(this.color, source.color);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.scaleByDistance = defaultValue(
      this.scaleByDistance,
      source.scaleByDistance
    );
    this.translucencyByDistance = defaultValue(
      this._translucencyByDistance,
      source.translucencyByDistance
    );
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.disableDepthTestDistance = defaultValue(
      this.disableDepthTestDistance,
      source.disableDepthTestDistance
    );
  };

  function createPolygonHierarchyProperty(value) {
    if (Array.isArray(value)) {
      // convert array of positions to PolygonHierarchy object
      value = new PolygonHierarchy(value);
    }
    return new ConstantProperty(value);
  }

  /**
   * @typedef {Object} PolygonGraphics.ConstructorOptions
   *
   * Initialization options for the PolygonGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the polygon.
   * @property {Property | PolygonHierarchy} [hierarchy] A Property specifying the {@link PolygonHierarchy}.
   * @property {Property | number} [height=0] A numeric Property specifying the altitude of the polygon relative to the ellipsoid surface.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | number} [extrudedHeight] A numeric Property specifying the altitude of the polygon's extruded face relative to the ellipsoid surface.
   * @property {Property | HeightReference} [extrudedHeightReference=HeightReference.NONE] A Property specifying what the extrudedHeight is relative to.
   * @property {Property | number} [stRotation=0.0] A numeric property specifying the rotation of the polygon texture counter-clockwise from north.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between each latitude and longitude point.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the polygon is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the polygon.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the polygon is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | boolean} [perPositionHeight=false] A boolean specifying whether or not the height of each position is used.
   * @property {Boolean | boolean} [closeTop=true] When false, leaves off the top of an extruded polygon open.
   * @property {Boolean | boolean} [closeBottom=true] When false, leaves off the bottom of an extruded polygon open.
   * @property {Property | ArcType} [arcType=ArcType.GEODESIC] The type of line the polygon edges must follow.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the polygon casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this polygon will be displayed.
   * @property {Property | ClassificationType} [classificationType=ClassificationType.BOTH] An enum Property specifying whether this polygon will classify terrain, 3D Tiles, or both when on the ground.
   * @property {ConstantProperty | number} [zIndex=0] A property specifying the zIndex used for ordering ground geometry.  Only has an effect if the polygon is constant and neither height or extrudedHeight are specified.
   */

  /**
   * Describes a polygon defined by an hierarchy of linear rings which make up the outer shape and any nested holes.
   * The polygon conforms to the curvature of the globe and can be placed on the surface or
   * at altitude and can optionally be extruded into a volume.
   *
   * @alias PolygonGraphics
   * @constructor
   *
   * @param {PolygonGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see Entity
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Polygon.html|Cesium Sandcastle Polygon Demo}
   */
  function PolygonGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._hierarchy = undefined;
    this._hierarchySubscription = undefined;
    this._height = undefined;
    this._heightSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._extrudedHeight = undefined;
    this._extrudedHeightSubscription = undefined;
    this._extrudedHeightReference = undefined;
    this._extrudedHeightReferenceSubscription = undefined;
    this._stRotation = undefined;
    this._stRotationSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._perPositionHeight = undefined;
    this._perPositionHeightSubscription = undefined;
    this._closeTop = undefined;
    this._closeTopSubscription = undefined;
    this._closeBottom = undefined;
    this._closeBottomSubscription = undefined;
    this._arcType = undefined;
    this._arcTypeSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._classificationType = undefined;
    this._classificationTypeSubscription = undefined;
    this._zIndex = undefined;
    this._zIndexSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(PolygonGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof PolygonGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the polygon.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the {@link PolygonHierarchy}.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     */
    hierarchy: createPropertyDescriptor(
      "hierarchy",
      undefined,
      createPolygonHierarchyProperty
    ),

    /**
     * Gets or sets the numeric Property specifying the constant altitude of the polygon.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    height: createPropertyDescriptor("height"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the polygon extrusion.
     * If {@link PolygonGraphics#perPositionHeight} is false, the volume starts at {@link PolygonGraphics#height} and ends at this altitude.
     * If {@link PolygonGraphics#perPositionHeight} is true, the volume starts at the height of each {@link PolygonGraphics#hierarchy} position and ends at this altitude.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     */
    extrudedHeight: createPropertyDescriptor("extrudedHeight"),

    /**
     * Gets or sets the Property specifying the extruded {@link HeightReference}.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    extrudedHeightReference: createPropertyDescriptor("extrudedHeightReference"),

    /**
     * Gets or sets the numeric property specifying the rotation of the polygon texture counter-clockwise from north.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    stRotation: createPropertyDescriptor("stRotation"),

    /**
     * Gets or sets the numeric Property specifying the angular distance between points on the polygon.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default {CesiumMath.RADIANS_PER_DEGREE}
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the boolean Property specifying whether the polygon is filled with the provided material.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the polygon.
     * @memberof PolygonGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the polygon is outlined.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Gets or sets the boolean specifying whether or not the the height of each position is used.
     * If true, the shape will have non-uniform altitude defined by the height of each {@link PolygonGraphics#hierarchy} position.
     * If false, the shape will have a constant altitude as specified by {@link PolygonGraphics#height}.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     */
    perPositionHeight: createPropertyDescriptor("perPositionHeight"),

    /**
     * Gets or sets a boolean specifying whether or not the top of an extruded polygon is included.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     */
    closeTop: createPropertyDescriptor("closeTop"),

    /**
     * Gets or sets a boolean specifying whether or not the bottom of an extruded polygon is included.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     */
    closeBottom: createPropertyDescriptor("closeBottom"),

    /**
     * Gets or sets the {@link ArcType} Property specifying the type of lines the polygon edges use.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default ArcType.GEODESIC
     */
    arcType: createPropertyDescriptor("arcType"),

    /**
     * Get or sets the enum Property specifying whether the polygon
     * casts or receives shadows from light sources.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this polygon will be displayed.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the {@link ClassificationType} Property specifying whether this polygon will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof PolygonGraphics.prototype
     * @type {Property|undefined}
     * @default ClassificationType.BOTH
     */
    classificationType: createPropertyDescriptor("classificationType"),

    /**
     * Gets or sets the zIndex Prperty specifying the ordering of ground geometry.  Only has an effect if the polygon is constant and neither height or extrudedHeight are specified.
     * @memberof PolygonGraphics.prototype
     * @type {ConstantProperty|undefined}
     * @default 0
     */
    zIndex: createPropertyDescriptor("zIndex"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {PolygonGraphics} [result] The object onto which to store the result.
   * @returns {PolygonGraphics} The modified result parameter or a new instance if one was not provided.
   */
  PolygonGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new PolygonGraphics(this);
    }
    result.show = this.show;
    result.hierarchy = this.hierarchy;
    result.height = this.height;
    result.heightReference = this.heightReference;
    result.extrudedHeight = this.extrudedHeight;
    result.extrudedHeightReference = this.extrudedHeightReference;
    result.stRotation = this.stRotation;
    result.granularity = this.granularity;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.perPositionHeight = this.perPositionHeight;
    result.closeTop = this.closeTop;
    result.closeBottom = this.closeBottom;
    result.arcType = this.arcType;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.classificationType = this.classificationType;
    result.zIndex = this.zIndex;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {PolygonGraphics} source The object to be merged into this object.
   */
  PolygonGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.hierarchy = defaultValue(this.hierarchy, source.hierarchy);
    this.height = defaultValue(this.height, source.height);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.extrudedHeight = defaultValue(
      this.extrudedHeight,
      source.extrudedHeight
    );
    this.extrudedHeightReference = defaultValue(
      this.extrudedHeightReference,
      source.extrudedHeightReference
    );
    this.stRotation = defaultValue(this.stRotation, source.stRotation);
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.perPositionHeight = defaultValue(
      this.perPositionHeight,
      source.perPositionHeight
    );
    this.closeTop = defaultValue(this.closeTop, source.closeTop);
    this.closeBottom = defaultValue(this.closeBottom, source.closeBottom);
    this.arcType = defaultValue(this.arcType, source.arcType);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.classificationType = defaultValue(
      this.classificationType,
      source.classificationType
    );
    this.zIndex = defaultValue(this.zIndex, source.zIndex);
  };

  /**
   * @typedef {Object} PolylineGraphics.ConstructorOptions
   *
   * Initialization options for the PolylineGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the polyline.
   * @property {Property | Array<Cartesian3>} [positions] A Property specifying the array of {@link Cartesian3} positions that define the line strip.
   * @property {Property | number} [width=1.0] A numeric Property specifying the width in pixels.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between each latitude and longitude if arcType is not ArcType.NONE.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to draw the polyline.
   * @property {MaterialProperty | Color} [depthFailMaterial] A property specifying the material used to draw the polyline when it is below the terrain.
   * @property {Property | ArcType} [arcType=ArcType.GEODESIC] The type of line the polyline segments must follow.
   * @property {Property | boolean} [clampToGround=false] A boolean Property specifying whether the Polyline should be clamped to the ground.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the polyline casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this polyline will be displayed.
   * @property {Property | ClassificationType} [classificationType=ClassificationType.BOTH] An enum Property specifying whether this polyline will classify terrain, 3D Tiles, or both when on the ground.
   * @property {Property | number} [zIndex=0] A Property specifying the zIndex used for ordering ground geometry. Only has an effect if `clampToGround` is true and polylines on terrain is supported.
   */

  /**
   * Describes a polyline. The first two positions define a line segment,
   * and each additional position defines a line segment from the previous position. The segments
   * can be linear connected points, great arcs, or clamped to terrain.
   *
   * @alias PolylineGraphics
   * @constructor
   *
   * @param {PolylineGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see Entity
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Polyline.html|Cesium Sandcastle Polyline Demo}
   */
  function PolylineGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._positions = undefined;
    this._positionsSubscription = undefined;
    this._width = undefined;
    this._widthSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._depthFailMaterial = undefined;
    this._depthFailMaterialSubscription = undefined;
    this._arcType = undefined;
    this._arcTypeSubscription = undefined;
    this._clampToGround = undefined;
    this._clampToGroundSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;
    this._classificationType = undefined;
    this._classificationTypeSubscription = undefined;
    this._zIndex = undefined;
    this._zIndexSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(PolylineGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof PolylineGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the polyline.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the array of {@link Cartesian3}
     * positions that define the line strip.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     */
    positions: createPropertyDescriptor("positions"),

    /**
     * Gets or sets the numeric Property specifying the width in pixels.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    width: createPropertyDescriptor("width"),

    /**
     * Gets or sets the numeric Property specifying the angular distance between each latitude and longitude if arcType is not ArcType.NONE and clampToGround is false.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default Cesium.Math.RADIANS_PER_DEGREE
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the Property specifying the material used to draw the polyline.
     * @memberof PolylineGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying the material used to draw the polyline when it fails the depth test.
     * <p>
     * Requires the EXT_frag_depth WebGL extension to render properly. If the extension is not supported,
     * there may be artifacts.
     * </p>
     * @memberof PolylineGraphics.prototype
     * @type {MaterialProperty}
     * @default undefined
     */
    depthFailMaterial: createMaterialPropertyDescriptor("depthFailMaterial"),

    /**
     * Gets or sets the {@link ArcType} Property specifying whether the line segments should be great arcs, rhumb lines or linearly connected.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default ArcType.GEODESIC
     */
    arcType: createPropertyDescriptor("arcType"),

    /**
     * Gets or sets the boolean Property specifying whether the polyline
     * should be clamped to the ground.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    clampToGround: createPropertyDescriptor("clampToGround"),

    /**
     * Get or sets the enum Property specifying whether the polyline
     * casts or receives shadows from light sources.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this polyline will be displayed.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the {@link ClassificationType} Property specifying whether this polyline will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof PolylineGraphics.prototype
     * @type {Property|undefined}
     * @default ClassificationType.BOTH
     */
    classificationType: createPropertyDescriptor("classificationType"),

    /**
     * Gets or sets the zIndex Property specifying the ordering of the polyline. Only has an effect if `clampToGround` is true and polylines on terrain is supported.
     * @memberof PolylineGraphics.prototype
     * @type {ConstantProperty|undefined}
     * @default 0
     */
    zIndex: createPropertyDescriptor("zIndex"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {PolylineGraphics} [result] The object onto which to store the result.
   * @returns {PolylineGraphics} The modified result parameter or a new instance if one was not provided.
   */
  PolylineGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new PolylineGraphics(this);
    }
    result.show = this.show;
    result.positions = this.positions;
    result.width = this.width;
    result.granularity = this.granularity;
    result.material = this.material;
    result.depthFailMaterial = this.depthFailMaterial;
    result.arcType = this.arcType;
    result.clampToGround = this.clampToGround;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.classificationType = this.classificationType;
    result.zIndex = this.zIndex;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {PolylineGraphics} source The object to be merged into this object.
   */
  PolylineGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.positions = defaultValue(this.positions, source.positions);
    this.width = defaultValue(this.width, source.width);
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.material = defaultValue(this.material, source.material);
    this.depthFailMaterial = defaultValue(
      this.depthFailMaterial,
      source.depthFailMaterial
    );
    this.arcType = defaultValue(this.arcType, source.arcType);
    this.clampToGround = defaultValue(this.clampToGround, source.clampToGround);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.classificationType = defaultValue(
      this.classificationType,
      source.classificationType
    );
    this.zIndex = defaultValue(this.zIndex, source.zIndex);
  };

  /**
   * @typedef {Object} PolylineVolumeGraphics.ConstructorOptions
   *
   * Initialization options for the PolylineVolumeGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the volume.
   * @property {Property | Array<Cartesian3>} [positions] A Property specifying the array of {@link Cartesian3} positions which define the line strip.
   * @property {Property | Array<Cartesian2>} [shape] A Property specifying the array of {@link Cartesian2} positions which define the shape to be extruded.
   * @property {Property | CornerType} [cornerType=CornerType.ROUNDED] A {@link CornerType} Property specifying the style of the corners.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between each latitude and longitude point.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the volume is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the volume.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the volume is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the volume casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this volume will be displayed.
   */

  /**
   * Describes a polyline volume defined as a line strip and corresponding two dimensional shape which is extruded along it.
   * The resulting volume conforms to the curvature of the globe.
   *
   * @alias PolylineVolumeGraphics
   * @constructor
   *
   * @param {PolylineVolumeGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see Entity
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Polyline%20Volume.html|Cesium Sandcastle Polyline Volume Demo}
   */
  function PolylineVolumeGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._positions = undefined;
    this._positionsSubscription = undefined;
    this._shape = undefined;
    this._shapeSubscription = undefined;
    this._cornerType = undefined;
    this._cornerTypeSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubsription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(PolylineVolumeGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof PolylineVolumeGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the volume.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the array of {@link Cartesian3} positions which define the line strip.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     */
    positions: createPropertyDescriptor("positions"),

    /**
     * Gets or sets the Property specifying the array of {@link Cartesian2} positions which define the shape to be extruded.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     */
    shape: createPropertyDescriptor("shape"),

    /**
     * Gets or sets the {@link CornerType} Property specifying the style of the corners.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default CornerType.ROUNDED
     */
    cornerType: createPropertyDescriptor("cornerType"),

    /**
     * Gets or sets the numeric Property specifying the angular distance between points on the volume.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default {CesiumMath.RADIANS_PER_DEGREE}
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the boolean Property specifying whether the volume is filled with the provided material.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the volume.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the volume is outlined.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Get or sets the enum Property specifying whether the volume
     * casts or receives shadows from light sources.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this volume will be displayed.
     * @memberof PolylineVolumeGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {PolylineVolumeGraphics} [result] The object onto which to store the result.
   * @returns {PolylineVolumeGraphics} The modified result parameter or a new instance if one was not provided.
   */
  PolylineVolumeGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new PolylineVolumeGraphics(this);
    }
    result.show = this.show;
    result.positions = this.positions;
    result.shape = this.shape;
    result.cornerType = this.cornerType;
    result.granularity = this.granularity;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {PolylineVolumeGraphics} source The object to be merged into this object.
   */
  PolylineVolumeGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.positions = defaultValue(this.positions, source.positions);
    this.shape = defaultValue(this.shape, source.shape);
    this.cornerType = defaultValue(this.cornerType, source.cornerType);
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  /**
   * @typedef {Object} RectangleGraphics.ConstructorOptions
   *
   * Initialization options for the RectangleGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the rectangle.
   * @property {Property | Rectangle} [coordinates] The Property specifying the {@link Rectangle}.
   * @property {Property | number} [height=0] A numeric Property specifying the altitude of the rectangle relative to the ellipsoid surface.
   * @property {Property | HeightReference} [heightReference=HeightReference.NONE] A Property specifying what the height is relative to.
   * @property {Property | number} [extrudedHeight] A numeric Property specifying the altitude of the rectangle's extruded face relative to the ellipsoid surface.
   * @property {Property | HeightReference} [extrudedHeightReference=HeightReference.NONE] A Property specifying what the extrudedHeight is relative to.
   * @property {Property | number} [rotation=0.0] A numeric property specifying the rotation of the rectangle clockwise from north.
   * @property {Property | number} [stRotation=0.0] A numeric property specifying the rotation of the rectangle texture counter-clockwise from north.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between points on the rectangle.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the rectangle is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the rectangle.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the rectangle is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the rectangle casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this rectangle will be displayed.
   * @property {Property | ClassificationType} [classificationType=ClassificationType.BOTH] An enum Property specifying whether this rectangle will classify terrain, 3D Tiles, or both when on the ground.
   * @property {Property | number} [zIndex=0] A Property specifying the zIndex used for ordering ground geometry.  Only has an effect if the rectangle is constant and neither height or extrudedHeight are specified.
   */

  /**
   * Describes graphics for a {@link Rectangle}.
   * The rectangle conforms to the curvature of the globe and can be placed on the surface or
   * at altitude and can optionally be extruded into a volume.
   *
   * @alias RectangleGraphics
   * @constructor
   *
   * @param {RectangleGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see Entity
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Rectangle.html|Cesium Sandcastle Rectangle Demo}
   */
  function RectangleGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._coordinates = undefined;
    this._coordinatesSubscription = undefined;
    this._height = undefined;
    this._heightSubscription = undefined;
    this._heightReference = undefined;
    this._heightReferenceSubscription = undefined;
    this._extrudedHeight = undefined;
    this._extrudedHeightSubscription = undefined;
    this._extrudedHeightReference = undefined;
    this._extrudedHeightReferenceSubscription = undefined;
    this._rotation = undefined;
    this._rotationSubscription = undefined;
    this._stRotation = undefined;
    this._stRotationSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distancedisplayConditionSubscription = undefined;
    this._classificationType = undefined;
    this._classificationTypeSubscription = undefined;
    this._zIndex = undefined;
    this._zIndexSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(RectangleGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof RectangleGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the rectangle.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the {@link Rectangle}.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     */
    coordinates: createPropertyDescriptor("coordinates"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the rectangle.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    height: createPropertyDescriptor("height"),

    /**
     * Gets or sets the Property specifying the {@link HeightReference}.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    heightReference: createPropertyDescriptor("heightReference"),

    /**
     * Gets or sets the numeric Property specifying the altitude of the rectangle extrusion.
     * Setting this property creates volume starting at height and ending at this altitude.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     */
    extrudedHeight: createPropertyDescriptor("extrudedHeight"),

    /**
     * Gets or sets the Property specifying the extruded {@link HeightReference}.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default HeightReference.NONE
     */
    extrudedHeightReference: createPropertyDescriptor("extrudedHeightReference"),

    /**
     * Gets or sets the numeric property specifying the rotation of the rectangle clockwise from north.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    rotation: createPropertyDescriptor("rotation"),

    /**
     * Gets or sets the numeric property specifying the rotation of the rectangle texture counter-clockwise from north.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default 0
     */
    stRotation: createPropertyDescriptor("stRotation"),

    /**
     * Gets or sets the numeric Property specifying the angular distance between points on the rectangle.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default {CesiumMath.RADIANS_PER_DEGREE}
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the boolean Property specifying whether the rectangle is filled with the provided material.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the rectangle.
     * @memberof RectangleGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the rectangle is outlined.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Get or sets the enum Property specifying whether the rectangle
     * casts or receives shadows from light sources.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this rectangle will be displayed.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),

    /**
     * Gets or sets the {@link ClassificationType} Property specifying whether this rectangle will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof RectangleGraphics.prototype
     * @type {Property|undefined}
     * @default ClassificationType.BOTH
     */
    classificationType: createPropertyDescriptor("classificationType"),

    /**
     * Gets or sets the zIndex Property specifying the ordering of the rectangle.  Only has an effect if the rectangle is constant and neither height or extrudedHeight are specified.
     * @memberof RectangleGraphics.prototype
     * @type {ConstantProperty|undefined}
     * @default 0
     */
    zIndex: createPropertyDescriptor("zIndex"),
  });

  /**
   * Duplicates this instance.
   *
   * @param {RectangleGraphics} [result] The object onto which to store the result.
   * @returns {RectangleGraphics} The modified result parameter or a new instance if one was not provided.
   */
  RectangleGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new RectangleGraphics(this);
    }
    result.show = this.show;
    result.coordinates = this.coordinates;
    result.height = this.height;
    result.heightReference = this.heightReference;
    result.extrudedHeight = this.extrudedHeight;
    result.extrudedHeightReference = this.extrudedHeightReference;
    result.rotation = this.rotation;
    result.stRotation = this.stRotation;
    result.granularity = this.granularity;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    result.classificationType = this.classificationType;
    result.zIndex = this.zIndex;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {RectangleGraphics} source The object to be merged into this object.
   */
  RectangleGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.coordinates = defaultValue(this.coordinates, source.coordinates);
    this.height = defaultValue(this.height, source.height);
    this.heightReference = defaultValue(
      this.heightReference,
      source.heightReference
    );
    this.extrudedHeight = defaultValue(
      this.extrudedHeight,
      source.extrudedHeight
    );
    this.extrudedHeightReference = defaultValue(
      this.extrudedHeightReference,
      source.extrudedHeightReference
    );
    this.rotation = defaultValue(this.rotation, source.rotation);
    this.stRotation = defaultValue(this.stRotation, source.stRotation);
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
    this.classificationType = defaultValue(
      this.classificationType,
      source.classificationType
    );
    this.zIndex = defaultValue(this.zIndex, source.zIndex);
  };

  /**
   * @typedef {Object} WallGraphics.ConstructorOptions
   *
   * Initialization options for the WallGraphics constructor
   *
   * @property {Property | boolean} [show=true] A boolean Property specifying the visibility of the wall.
   * @property {Property | Array<Cartesian3>} [positions] A Property specifying the array of {@link Cartesian3} positions which define the top of the wall.
   * @property {Property | Array<number>} [minimumHeights] A Property specifying an array of heights to be used for the bottom of the wall instead of the globe surface.
   * @property {Property | Array<number>} [maximumHeights] A Property specifying an array of heights to be used for the top of the wall instead of the height of each position.
   * @property {Property | number} [granularity=Cesium.Math.RADIANS_PER_DEGREE] A numeric Property specifying the angular distance between each latitude and longitude point.
   * @property {Property | boolean} [fill=true] A boolean Property specifying whether the wall is filled with the provided material.
   * @property {MaterialProperty | Color} [material=Color.WHITE] A Property specifying the material used to fill the wall.
   * @property {Property | boolean} [outline=false] A boolean Property specifying whether the wall is outlined.
   * @property {Property | Color} [outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @property {Property | number} [outlineWidth=1.0] A numeric Property specifying the width of the outline.
   * @property {Property | ShadowMode} [shadows=ShadowMode.DISABLED] An enum Property specifying whether the wall casts or receives shadows from light sources.
   * @property {Property | DistanceDisplayCondition} [distanceDisplayCondition] A Property specifying at what distance from the camera that this wall will be displayed.
   */

  /**
   * Describes a two dimensional wall defined as a line strip and optional maximum and minimum heights.
   * The wall conforms to the curvature of the globe and can be placed along the surface or at altitude.
   *
   * @alias WallGraphics
   * @constructor
   *
   * @param {WallGraphics.ConstructorOptions} [options] Object describing initialization options
   *
   * @see Entity
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Wall.html|Cesium Sandcastle Wall Demo}
   */
  function WallGraphics(options) {
    this._definitionChanged = new Event();
    this._show = undefined;
    this._showSubscription = undefined;
    this._positions = undefined;
    this._positionsSubscription = undefined;
    this._minimumHeights = undefined;
    this._minimumHeightsSubscription = undefined;
    this._maximumHeights = undefined;
    this._maximumHeightsSubscription = undefined;
    this._granularity = undefined;
    this._granularitySubscription = undefined;
    this._fill = undefined;
    this._fillSubscription = undefined;
    this._material = undefined;
    this._materialSubscription = undefined;
    this._outline = undefined;
    this._outlineSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;
    this._shadows = undefined;
    this._shadowsSubscription = undefined;
    this._distanceDisplayCondition = undefined;
    this._distanceDisplayConditionSubscription = undefined;

    this.merge(defaultValue(options, defaultValue.EMPTY_OBJECT));
  }

  Object.defineProperties(WallGraphics.prototype, {
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof WallGraphics.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the boolean Property specifying the visibility of the wall.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    show: createPropertyDescriptor("show"),

    /**
     * Gets or sets the Property specifying the array of {@link Cartesian3} positions which define the top of the wall.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     */
    positions: createPropertyDescriptor("positions"),

    /**
     * Gets or sets the Property specifying an array of heights to be used for the bottom of the wall instead of the surface of the globe.
     * If defined, the array must be the same length as {@link Wall#positions}.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     */
    minimumHeights: createPropertyDescriptor("minimumHeights"),

    /**
     * Gets or sets the Property specifying an array of heights to be used for the top of the wall instead of the height of each position.
     * If defined, the array must be the same length as {@link Wall#positions}.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     */
    maximumHeights: createPropertyDescriptor("maximumHeights"),

    /**
     * Gets or sets the numeric Property specifying the angular distance between points on the wall.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default {CesiumMath.RADIANS_PER_DEGREE}
     */
    granularity: createPropertyDescriptor("granularity"),

    /**
     * Gets or sets the boolean Property specifying whether the wall is filled with the provided material.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default true
     */
    fill: createPropertyDescriptor("fill"),

    /**
     * Gets or sets the Property specifying the material used to fill the wall.
     * @memberof WallGraphics.prototype
     * @type {MaterialProperty}
     * @default Color.WHITE
     */
    material: createMaterialPropertyDescriptor("material"),

    /**
     * Gets or sets the Property specifying whether the wall is outlined.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default false
     */
    outline: createPropertyDescriptor("outline"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),

    /**
     * Get or sets the enum Property specifying whether the wall
     * casts or receives shadows from light sources.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     * @default ShadowMode.DISABLED
     */
    shadows: createPropertyDescriptor("shadows"),

    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this wall will be displayed.
     * @memberof WallGraphics.prototype
     * @type {Property|undefined}
     */
    distanceDisplayCondition: createPropertyDescriptor(
      "distanceDisplayCondition"
    ),
  });

  /**
   * Duplicates this instance.
   *
   * @param {WallGraphics} [result] The object onto which to store the result.
   * @returns {WallGraphics} The modified result parameter or a new instance if one was not provided.
   */
  WallGraphics.prototype.clone = function (result) {
    if (!defined(result)) {
      return new WallGraphics(this);
    }
    result.show = this.show;
    result.positions = this.positions;
    result.minimumHeights = this.minimumHeights;
    result.maximumHeights = this.maximumHeights;
    result.granularity = this.granularity;
    result.fill = this.fill;
    result.material = this.material;
    result.outline = this.outline;
    result.outlineColor = this.outlineColor;
    result.outlineWidth = this.outlineWidth;
    result.shadows = this.shadows;
    result.distanceDisplayCondition = this.distanceDisplayCondition;
    return result;
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {WallGraphics} source The object to be merged into this object.
   */
  WallGraphics.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.show = defaultValue(this.show, source.show);
    this.positions = defaultValue(this.positions, source.positions);
    this.minimumHeights = defaultValue(
      this.minimumHeights,
      source.minimumHeights
    );
    this.maximumHeights = defaultValue(
      this.maximumHeights,
      source.maximumHeights
    );
    this.granularity = defaultValue(this.granularity, source.granularity);
    this.fill = defaultValue(this.fill, source.fill);
    this.material = defaultValue(this.material, source.material);
    this.outline = defaultValue(this.outline, source.outline);
    this.outlineColor = defaultValue(this.outlineColor, source.outlineColor);
    this.outlineWidth = defaultValue(this.outlineWidth, source.outlineWidth);
    this.shadows = defaultValue(this.shadows, source.shadows);
    this.distanceDisplayCondition = defaultValue(
      this.distanceDisplayCondition,
      source.distanceDisplayCondition
    );
  };

  var cartoScratch$1 = new Cartographic();

  function createConstantPositionProperty(value) {
    return new ConstantPositionProperty(value);
  }

  function createPositionPropertyDescriptor(name) {
    return createPropertyDescriptor(
      name,
      undefined,
      createConstantPositionProperty
    );
  }

  function createPropertyTypeDescriptor(name, Type) {
    return createPropertyDescriptor(name, undefined, function (value) {
      if (value instanceof Type) {
        return value;
      }
      return new Type(value);
    });
  }

  /**
   * @typedef {Object} Entity.ConstructorOptions
   *
   * Initialization options for the Entity constructor
   *
   * @property {String} [id] A unique identifier for this object. If none is provided, a GUID is generated.
   * @property {String} [name] A human readable name to display to users. It does not have to be unique.
   * @property {TimeIntervalCollection} [availability] The availability, if any, associated with this object.
   * @property {Boolean} [show] A boolean value indicating if the entity and its children are displayed.
   * @property {Property | string} [description] A string Property specifying an HTML description for this entity.
   * @property {PositionProperty | Cartesian3} [position] A Property specifying the entity position.
   * @property {Property} [orientation] A Property specifying the entity orientation.
   * @property {Property} [viewFrom] A suggested initial offset for viewing this object.
   * @property {Entity} [parent] A parent entity to associate with this entity.
   * @property {BillboardGraphics | BillboardGraphics.ConstructorOptions} [billboard] A billboard to associate with this entity.
   * @property {BoxGraphics | BoxGraphics.ConstructorOptions} [box] A box to associate with this entity.
   * @property {CorridorGraphics | CorridorGraphics.ConstructorOptions} [corridor] A corridor to associate with this entity.
   * @property {CylinderGraphics | CylinderGraphics.ConstructorOptions} [cylinder] A cylinder to associate with this entity.
   * @property {EllipseGraphics | EllipseGraphics.ConstructorOptions} [ellipse] A ellipse to associate with this entity.
   * @property {EllipsoidGraphics | EllipsoidGraphics.ConstructorOptions} [ellipsoid] A ellipsoid to associate with this entity.
   * @property {LabelGraphics | LabelGraphics.ConstructorOptions} [label] A options.label to associate with this entity.
   * @property {ModelGraphics | ModelGraphics.ConstructorOptions} [model] A model to associate with this entity.
   * @property {Cesium3DTilesetGraphics | Cesium3DTilesetGraphics.ConstructorOptions} [tileset] A 3D Tiles tileset to associate with this entity.
   * @property {PathGraphics | PathGraphics.ConstructorOptions} [path] A path to associate with this entity.
   * @property {PlaneGraphics | PlaneGraphics.ConstructorOptions} [plane] A plane to associate with this entity.
   * @property {PointGraphics | PointGraphics.ConstructorOptions} [point] A point to associate with this entity.
   * @property {PolygonGraphics | PolygonGraphics.ConstructorOptions} [polygon] A polygon to associate with this entity.
   * @property {PolylineGraphics | PolylineGraphics.ConstructorOptions} [polyline] A polyline to associate with this entity.
   * @property {PropertyBag | Object.<string,*>} [properties] Arbitrary properties to associate with this entity.
   * @property {PolylineVolumeGraphics | PolylineVolumeGraphics.ConstructorOptions} [polylineVolume] A polylineVolume to associate with this entity.
   * @property {RectangleGraphics | RectangleGraphics.ConstructorOptions} [rectangle] A rectangle to associate with this entity.
   * @property {WallGraphics | WallGraphics.ConstructorOptions} [wall] A wall to associate with this entity.
   */

  /**
   * Entity instances aggregate multiple forms of visualization into a single high-level object.
   * They can be created manually and added to {@link Viewer#entities} or be produced by
   * data sources, such as {@link CzmlDataSource} and {@link GeoJsonDataSource}.
   * @alias Entity
   * @constructor
   *
   * @param {Entity.ConstructorOptions} [options] Object describing initialization options
   *
   * @see {@link https://cesium.com/docs/tutorials/creating-entities/|Creating Entities}
   */
  function Entity(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var id = options.id;
    if (!defined(id)) {
      id = createGuid();
    }

    this._availability = undefined;
    this._id = id;
    this._definitionChanged = new Event();
    this._name = options.name;
    this._show = defaultValue(options.show, true);
    this._parent = undefined;
    this._propertyNames = [
      "billboard",
      "box",
      "corridor",
      "cylinder",
      "description",
      "ellipse", //
      "ellipsoid",
      "label",
      "model",
      "tileset",
      "orientation",
      "path",
      "plane",
      "point",
      "polygon", //
      "polyline",
      "polylineVolume",
      "position",
      "properties",
      "rectangle",
      "viewFrom",
      "wall",
    ];

    this._billboard = undefined;
    this._billboardSubscription = undefined;
    this._box = undefined;
    this._boxSubscription = undefined;
    this._corridor = undefined;
    this._corridorSubscription = undefined;
    this._cylinder = undefined;
    this._cylinderSubscription = undefined;
    this._description = undefined;
    this._descriptionSubscription = undefined;
    this._ellipse = undefined;
    this._ellipseSubscription = undefined;
    this._ellipsoid = undefined;
    this._ellipsoidSubscription = undefined;
    this._label = undefined;
    this._labelSubscription = undefined;
    this._model = undefined;
    this._modelSubscription = undefined;
    this._tileset = undefined;
    this._tilesetSubscription = undefined;
    this._orientation = undefined;
    this._orientationSubscription = undefined;
    this._path = undefined;
    this._pathSubscription = undefined;
    this._plane = undefined;
    this._planeSubscription = undefined;
    this._point = undefined;
    this._pointSubscription = undefined;
    this._polygon = undefined;
    this._polygonSubscription = undefined;
    this._polyline = undefined;
    this._polylineSubscription = undefined;
    this._polylineVolume = undefined;
    this._polylineVolumeSubscription = undefined;
    this._position = undefined;
    this._positionSubscription = undefined;
    this._properties = undefined;
    this._propertiesSubscription = undefined;
    this._rectangle = undefined;
    this._rectangleSubscription = undefined;
    this._viewFrom = undefined;
    this._viewFromSubscription = undefined;
    this._wall = undefined;
    this._wallSubscription = undefined;
    this._children = [];

    /**
     * Gets or sets the entity collection that this entity belongs to.
     * @type {EntityCollection}
     */
    this.entityCollection = undefined;

    this.parent = options.parent;
    this.merge(options);
  }

  function updateShow(entity, children, isShowing) {
    var length = children.length;
    for (var i = 0; i < length; i++) {
      var child = children[i];
      var childShow = child._show;
      var oldValue = !isShowing && childShow;
      var newValue = isShowing && childShow;
      if (oldValue !== newValue) {
        updateShow(child, child._children, isShowing);
      }
    }
    entity._definitionChanged.raiseEvent(
      entity,
      "isShowing",
      isShowing,
      !isShowing
    );
  }

  Object.defineProperties(Entity.prototype, {
    /**
     * The availability, if any, associated with this object.
     * If availability is undefined, it is assumed that this object's
     * other properties will return valid data for any provided time.
     * If availability exists, the objects other properties will only
     * provide valid data if queried within the given interval.
     * @memberof Entity.prototype
     * @type {TimeIntervalCollection|undefined}
     */
    availability: createRawPropertyDescriptor("availability"),
    /**
     * Gets the unique ID associated with this object.
     * @memberof Entity.prototype
     * @type {String}
     */
    id: {
      get: function () {
        return this._id;
      },
    },
    /**
     * Gets the event that is raised whenever a property or sub-property is changed or modified.
     * @memberof Entity.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the name of the object.  The name is intended for end-user
     * consumption and does not need to be unique.
     * @memberof Entity.prototype
     * @type {String|undefined}
     */
    name: createRawPropertyDescriptor("name"),
    /**
     * Gets or sets whether this entity should be displayed. When set to true,
     * the entity is only displayed if the parent entity's show property is also true.
     * @memberof Entity.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (value === this._show) {
          return;
        }

        var wasShowing = this.isShowing;
        this._show = value;
        var isShowing = this.isShowing;

        if (wasShowing !== isShowing) {
          updateShow(this, this._children, isShowing);
        }

        this._definitionChanged.raiseEvent(this, "show", value, !value);
      },
    },
    /**
     * Gets whether this entity is being displayed, taking into account
     * the visibility of any ancestor entities.
     * @memberof Entity.prototype
     * @type {Boolean}
     */
    isShowing: {
      get: function () {
        return (
          this._show &&
          (!defined(this.entityCollection) || this.entityCollection.show) &&
          (!defined(this._parent) || this._parent.isShowing)
        );
      },
    },
    /**
     * Gets or sets the parent object.
     * @memberof Entity.prototype
     * @type {Entity|undefined}
     */
    parent: {
      get: function () {
        return this._parent;
      },
      set: function (value) {
        var oldValue = this._parent;

        if (oldValue === value) {
          return;
        }

        var wasShowing = this.isShowing;
        if (defined(oldValue)) {
          var index = oldValue._children.indexOf(this);
          oldValue._children.splice(index, 1);
        }

        this._parent = value;
        if (defined(value)) {
          value._children.push(this);
        }

        var isShowing = this.isShowing;

        if (wasShowing !== isShowing) {
          updateShow(this, this._children, isShowing);
        }

        this._definitionChanged.raiseEvent(this, "parent", value, oldValue);
      },
    },
    /**
     * Gets the names of all properties registered on this instance.
     * @memberof Entity.prototype
     * @type {string[]}
     */
    propertyNames: {
      get: function () {
        return this._propertyNames;
      },
    },
    /**
     * Gets or sets the billboard.
     * @memberof Entity.prototype
     * @type {BillboardGraphics|undefined}
     */
    billboard: createPropertyTypeDescriptor("billboard", BillboardGraphics),
    /**
     * Gets or sets the box.
     * @memberof Entity.prototype
     * @type {BoxGraphics|undefined}
     */
    box: createPropertyTypeDescriptor("box", BoxGraphics),
    /**
     * Gets or sets the corridor.
     * @memberof Entity.prototype
     * @type {CorridorGraphics|undefined}
     */
    corridor: createPropertyTypeDescriptor("corridor", CorridorGraphics),
    /**
     * Gets or sets the cylinder.
     * @memberof Entity.prototype
     * @type {CylinderGraphics|undefined}
     */
    cylinder: createPropertyTypeDescriptor("cylinder", CylinderGraphics),
    /**
     * Gets or sets the description.
     * @memberof Entity.prototype
     * @type {Property|undefined}
     */
    description: createPropertyDescriptor("description"),
    /**
     * Gets or sets the ellipse.
     * @memberof Entity.prototype
     * @type {EllipseGraphics|undefined}
     */
    ellipse: createPropertyTypeDescriptor("ellipse", EllipseGraphics),
    /**
     * Gets or sets the ellipsoid.
     * @memberof Entity.prototype
     * @type {EllipsoidGraphics|undefined}
     */
    ellipsoid: createPropertyTypeDescriptor("ellipsoid", EllipsoidGraphics),
    /**
     * Gets or sets the label.
     * @memberof Entity.prototype
     * @type {LabelGraphics|undefined}
     */
    label: createPropertyTypeDescriptor("label", LabelGraphics),
    /**
     * Gets or sets the model.
     * @memberof Entity.prototype
     * @type {ModelGraphics|undefined}
     */
    model: createPropertyTypeDescriptor("model", ModelGraphics),
    /**
     * Gets or sets the tileset.
     * @memberof Entity.prototype
     * @type {Cesium3DTilesetGraphics|undefined}
     */
    tileset: createPropertyTypeDescriptor("tileset", Cesium3DTilesetGraphics),
    /**
     * Gets or sets the orientation.
     * @memberof Entity.prototype
     * @type {Property|undefined}
     */
    orientation: createPropertyDescriptor("orientation"),
    /**
     * Gets or sets the path.
     * @memberof Entity.prototype
     * @type {PathGraphics|undefined}
     */
    path: createPropertyTypeDescriptor("path", PathGraphics),
    /**
     * Gets or sets the plane.
     * @memberof Entity.prototype
     * @type {PlaneGraphics|undefined}
     */
    plane: createPropertyTypeDescriptor("plane", PlaneGraphics),
    /**
     * Gets or sets the point graphic.
     * @memberof Entity.prototype
     * @type {PointGraphics|undefined}
     */
    point: createPropertyTypeDescriptor("point", PointGraphics),
    /**
     * Gets or sets the polygon.
     * @memberof Entity.prototype
     * @type {PolygonGraphics|undefined}
     */
    polygon: createPropertyTypeDescriptor("polygon", PolygonGraphics),
    /**
     * Gets or sets the polyline.
     * @memberof Entity.prototype
     * @type {PolylineGraphics|undefined}
     */
    polyline: createPropertyTypeDescriptor("polyline", PolylineGraphics),
    /**
     * Gets or sets the polyline volume.
     * @memberof Entity.prototype
     * @type {PolylineVolumeGraphics|undefined}
     */
    polylineVolume: createPropertyTypeDescriptor(
      "polylineVolume",
      PolylineVolumeGraphics
    ),
    /**
     * Gets or sets the bag of arbitrary properties associated with this entity.
     * @memberof Entity.prototype
     * @type {PropertyBag|undefined}
     */
    properties: createPropertyTypeDescriptor("properties", PropertyBag),
    /**
     * Gets or sets the position.
     * @memberof Entity.prototype
     * @type {PositionProperty|undefined}
     */
    position: createPositionPropertyDescriptor("position"),
    /**
     * Gets or sets the rectangle.
     * @memberof Entity.prototype
     * @type {RectangleGraphics|undefined}
     */
    rectangle: createPropertyTypeDescriptor("rectangle", RectangleGraphics),
    /**
     * Gets or sets the suggested initial offset when tracking this object.
     * The offset is typically defined in the east-north-up reference frame,
     * but may be another frame depending on the object's velocity.
     * @memberof Entity.prototype
     * @type {Property|undefined}
     */
    viewFrom: createPropertyDescriptor("viewFrom"),
    /**
     * Gets or sets the wall.
     * @memberof Entity.prototype
     * @type {WallGraphics|undefined}
     */
    wall: createPropertyTypeDescriptor("wall", WallGraphics),
  });

  /**
   * Given a time, returns true if this object should have data during that time.
   *
   * @param {JulianDate} time The time to check availability for.
   * @returns {Boolean} true if the object should have data during the provided time, false otherwise.
   */
  Entity.prototype.isAvailable = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var availability = this._availability;
    return !defined(availability) || availability.contains(time);
  };

  /**
   * Adds a property to this object.  Once a property is added, it can be
   * observed with {@link Entity#definitionChanged} and composited
   * with {@link CompositeEntityCollection}
   *
   * @param {String} propertyName The name of the property to add.
   *
   * @exception {DeveloperError} "propertyName" is a reserved property name.
   * @exception {DeveloperError} "propertyName" is already a registered property.
   */
  Entity.prototype.addProperty = function (propertyName) {
    var propertyNames = this._propertyNames;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(propertyName)) {
      throw new DeveloperError("propertyName is required.");
    }
    if (propertyNames.indexOf(propertyName) !== -1) {
      throw new DeveloperError(
        propertyName + " is already a registered property."
      );
    }
    if (propertyName in this) {
      throw new DeveloperError(propertyName + " is a reserved property name.");
    }
    //>>includeEnd('debug');

    propertyNames.push(propertyName);
    Object.defineProperty(
      this,
      propertyName,
      createRawPropertyDescriptor(propertyName, true)
    );
  };

  /**
   * Removed a property previously added with addProperty.
   *
   * @param {String} propertyName The name of the property to remove.
   *
   * @exception {DeveloperError} "propertyName" is a reserved property name.
   * @exception {DeveloperError} "propertyName" is not a registered property.
   */
  Entity.prototype.removeProperty = function (propertyName) {
    var propertyNames = this._propertyNames;
    var index = propertyNames.indexOf(propertyName);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(propertyName)) {
      throw new DeveloperError("propertyName is required.");
    }
    if (index === -1) {
      throw new DeveloperError(propertyName + " is not a registered property.");
    }
    //>>includeEnd('debug');

    this._propertyNames.splice(index, 1);
    delete this[propertyName];
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {Entity} source The object to be merged into this object.
   */
  Entity.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    //Name, show, and availability are not Property objects and are currently handled differently.
    //source.show is intentionally ignored because this.show always has a value.
    this.name = defaultValue(this.name, source.name);
    this.availability = defaultValue(this.availability, source.availability);

    var propertyNames = this._propertyNames;
    var sourcePropertyNames = defined(source._propertyNames)
      ? source._propertyNames
      : Object.keys(source);
    var propertyNamesLength = sourcePropertyNames.length;
    for (var i = 0; i < propertyNamesLength; i++) {
      var name = sourcePropertyNames[i];

      //While source is required by the API to be an Entity, we internally call this method from the
      //constructor with an options object to configure initial custom properties.
      //So we need to ignore reserved-non-property.
      if (name === "parent" || name === "name" || name === "availability") {
        continue;
      }

      var targetProperty = this[name];
      var sourceProperty = source[name];

      //Custom properties that are registered on the source entity must also
      //get registered on this entity.
      if (!defined(targetProperty) && propertyNames.indexOf(name) === -1) {
        this.addProperty(name);
      }

      if (defined(sourceProperty)) {
        if (defined(targetProperty)) {
          if (defined(targetProperty.merge)) {
            targetProperty.merge(sourceProperty);
          }
        } else if (
          defined(sourceProperty.merge) &&
          defined(sourceProperty.clone)
        ) {
          this[name] = sourceProperty.clone();
        } else {
          this[name] = sourceProperty;
        }
      }
    }
  };

  var matrix3Scratch$1 = new Matrix3();
  var positionScratch$5 = new Cartesian3();
  var orientationScratch = new Quaternion();

  /**
   * Computes the model matrix for the entity's transform at specified time. Returns undefined if orientation or position
   * are undefined.
   *
   * @param {JulianDate} time The time to retrieve model matrix for.
   * @param {Matrix4} [result] The object onto which to store the result.
   *
   * @returns {Matrix4} The modified result parameter or a new Matrix4 instance if one was not provided. Result is undefined if position or orientation are undefined.
   */
  Entity.prototype.computeModelMatrix = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("time", time);
    //>>includeEnd('debug');
    var position = Property.getValueOrUndefined(
      this._position,
      time,
      positionScratch$5
    );
    if (!defined(position)) {
      return undefined;
    }

    var orientation = Property.getValueOrUndefined(
      this._orientation,
      time,
      orientationScratch
    );
    if (!defined(orientation)) {
      result = Transforms.eastNorthUpToFixedFrame(position, undefined, result);
    } else {
      result = Matrix4.fromRotationTranslation(
        Matrix3.fromQuaternion(orientation, matrix3Scratch$1),
        position,
        result
      );
    }
    return result;
  };

  /**
   * @private
   */
  Entity.prototype.computeModelMatrixForHeightReference = function (
    time,
    heightReferenceProperty,
    heightOffset,
    ellipsoid,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("time", time);
    //>>includeEnd('debug');
    var heightReference = Property.getValueOrDefault(
      heightReferenceProperty,
      time,
      HeightReference$1.NONE
    );
    var position = Property.getValueOrUndefined(
      this._position,
      time,
      positionScratch$5
    );
    if (
      heightReference === HeightReference$1.NONE ||
      !defined(position) ||
      Cartesian3.equalsEpsilon(position, Cartesian3.ZERO, CesiumMath.EPSILON8)
    ) {
      return this.computeModelMatrix(time, result);
    }

    var carto = ellipsoid.cartesianToCartographic(position, cartoScratch$1);
    if (heightReference === HeightReference$1.CLAMP_TO_GROUND) {
      carto.height = heightOffset;
    } else {
      carto.height += heightOffset;
    }
    position = ellipsoid.cartographicToCartesian(carto, position);

    var orientation = Property.getValueOrUndefined(
      this._orientation,
      time,
      orientationScratch
    );
    if (!defined(orientation)) {
      result = Transforms.eastNorthUpToFixedFrame(position, undefined, result);
    } else {
      result = Matrix4.fromRotationTranslation(
        Matrix3.fromQuaternion(orientation, matrix3Scratch$1),
        position,
        result
      );
    }
    return result;
  };

  /**
   * Checks if the given Scene supports materials besides Color on Entities draped on terrain or 3D Tiles.
   * If this feature is not supported, Entities with non-color materials but no `height` will
   * instead be rendered as if height is 0.
   *
   * @param {Scene} scene The current scene.
   * @returns {Boolean} Whether or not the current scene supports materials for entities on terrain.
   */
  Entity.supportsMaterialsforEntitiesOnTerrain = function (scene) {
    return GroundPrimitive.supportsMaterials(scene);
  };

  /**
   * Checks if the given Scene supports polylines clamped to terrain or 3D Tiles.
   * If this feature is not supported, Entities with PolylineGraphics will be rendered with vertices at
   * the provided heights and using the `arcType` parameter instead of clamped to the ground.
   *
   * @param {Scene} scene The current scene.
   * @returns {Boolean} Whether or not the current scene supports polylines on terrain or 3D TIles.
   */
  Entity.supportsPolylinesOnTerrain = function (scene) {
    return GroundPolylinePrimitive.isSupported(scene);
  };

  var defaultMaterial = new ColorMaterialProperty(Color.WHITE);
  var defaultShow = new ConstantProperty(true);
  var defaultFill = new ConstantProperty(true);
  var defaultOutline = new ConstantProperty(false);
  var defaultOutlineColor = new ConstantProperty(Color.BLACK);
  var defaultShadows = new ConstantProperty(ShadowMode$1.DISABLED);
  var defaultDistanceDisplayCondition = new ConstantProperty(
    new DistanceDisplayCondition()
  );
  var defaultClassificationType = new ConstantProperty(ClassificationType$1.BOTH);

  /**
   * An abstract class for updating geometry entities.
   * @alias GeometryUpdater
   * @constructor
   *
   * @param {Object} options An object with the following properties:
   * @param {Entity} options.entity The entity containing the geometry to be visualized.
   * @param {Scene} options.scene The scene where visualization is taking place.
   * @param {Object} options.geometryOptions Options for the geometry
   * @param {String} options.geometryPropertyName The geometry property name
   * @param {String[]} options.observedPropertyNames The entity properties this geometry cares about
   */
  function GeometryUpdater(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.entity", options.entity);
    Check.defined("options.scene", options.scene);
    Check.defined("options.geometryOptions", options.geometryOptions);
    Check.defined("options.geometryPropertyName", options.geometryPropertyName);
    Check.defined("options.observedPropertyNames", options.observedPropertyNames);
    //>>includeEnd('debug');

    var entity = options.entity;
    var geometryPropertyName = options.geometryPropertyName;

    this._entity = entity;
    this._scene = options.scene;
    this._fillEnabled = false;
    this._isClosed = false;
    this._onTerrain = false;
    this._dynamic = false;
    this._outlineEnabled = false;
    this._geometryChanged = new Event();
    this._showProperty = undefined;
    this._materialProperty = undefined;
    this._showOutlineProperty = undefined;
    this._outlineColorProperty = undefined;
    this._outlineWidth = 1.0;
    this._shadowsProperty = undefined;
    this._distanceDisplayConditionProperty = undefined;
    this._classificationTypeProperty = undefined;
    this._options = options.geometryOptions;
    this._geometryPropertyName = geometryPropertyName;
    this._id = geometryPropertyName + "-" + entity.id;
    this._observedPropertyNames = options.observedPropertyNames;
    this._supportsMaterialsforEntitiesOnTerrain = Entity.supportsMaterialsforEntitiesOnTerrain(
      options.scene
    );
  }

  Object.defineProperties(GeometryUpdater.prototype, {
    /**
     * Gets the unique ID associated with this updater
     * @memberof GeometryUpdater.prototype
     * @type {String}
     * @readonly
     */
    id: {
      get: function () {
        return this._id;
      },
    },
    /**
     * Gets the entity associated with this geometry.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Entity}
     * @readonly
     */
    entity: {
      get: function () {
        return this._entity;
      },
    },
    /**
     * Gets a value indicating if the geometry has a fill component.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    fillEnabled: {
      get: function () {
        return this._fillEnabled;
      },
    },
    /**
     * Gets a value indicating if fill visibility varies with simulation time.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    hasConstantFill: {
      get: function () {
        return (
          !this._fillEnabled ||
          (!defined(this._entity.availability) &&
            Property.isConstant(this._showProperty) &&
            Property.isConstant(this._fillProperty))
        );
      },
    },
    /**
     * Gets the material property used to fill the geometry.
     * @memberof GeometryUpdater.prototype
     *
     * @type {MaterialProperty}
     * @readonly
     */
    fillMaterialProperty: {
      get: function () {
        return this._materialProperty;
      },
    },
    /**
     * Gets a value indicating if the geometry has an outline component.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    outlineEnabled: {
      get: function () {
        return this._outlineEnabled;
      },
    },
    /**
     * Gets a value indicating if the geometry has an outline component.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    hasConstantOutline: {
      get: function () {
        return (
          !this._outlineEnabled ||
          (!defined(this._entity.availability) &&
            Property.isConstant(this._showProperty) &&
            Property.isConstant(this._showOutlineProperty))
        );
      },
    },
    /**
     * Gets the {@link Color} property for the geometry outline.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    outlineColorProperty: {
      get: function () {
        return this._outlineColorProperty;
      },
    },
    /**
     * Gets the constant with of the geometry outline, in pixels.
     * This value is only valid if isDynamic is false.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Number}
     * @readonly
     */
    outlineWidth: {
      get: function () {
        return this._outlineWidth;
      },
    },
    /**
     * Gets the property specifying whether the geometry
     * casts or receives shadows from light sources.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    shadowsProperty: {
      get: function () {
        return this._shadowsProperty;
      },
    },
    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this geometry will be displayed.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    distanceDisplayConditionProperty: {
      get: function () {
        return this._distanceDisplayConditionProperty;
      },
    },
    /**
     * Gets or sets the {@link ClassificationType} Property specifying if this geometry will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    classificationTypeProperty: {
      get: function () {
        return this._classificationTypeProperty;
      },
    },
    /**
     * Gets a value indicating if the geometry is time-varying.
     * If true, all visualization is delegated to a DynamicGeometryUpdater
     * returned by GeometryUpdater#createDynamicUpdater.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isDynamic: {
      get: function () {
        return this._dynamic;
      },
    },
    /**
     * Gets a value indicating if the geometry is closed.
     * This property is only valid for static geometry.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isClosed: {
      get: function () {
        return this._isClosed;
      },
    },
    /**
     * Gets a value indicating if the geometry should be drawn on terrain.
     * @memberof EllipseGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    onTerrain: {
      get: function () {
        return this._onTerrain;
      },
    },
    /**
     * Gets an event that is raised whenever the public properties
     * of this updater change.
     * @memberof GeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    geometryChanged: {
      get: function () {
        return this._geometryChanged;
      },
    },
  });

  /**
   * Checks if the geometry is outlined at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve visibility.
   * @returns {Boolean} true if geometry is outlined at the provided time, false otherwise.
   */
  GeometryUpdater.prototype.isOutlineVisible = function (time) {
    var entity = this._entity;
    var visible =
      this._outlineEnabled &&
      entity.isAvailable(time) &&
      this._showProperty.getValue(time) &&
      this._showOutlineProperty.getValue(time);
    return defaultValue(visible, false);
  };

  /**
   * Checks if the geometry is filled at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve visibility.
   * @returns {Boolean} true if geometry is filled at the provided time, false otherwise.
   */
  GeometryUpdater.prototype.isFilled = function (time) {
    var entity = this._entity;
    var visible =
      this._fillEnabled &&
      entity.isAvailable(time) &&
      this._showProperty.getValue(time) &&
      this._fillProperty.getValue(time);
    return defaultValue(visible, false);
  };

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @function
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  GeometryUpdater.prototype.createFillGeometryInstance =
    DeveloperError.throwInstantiationError;

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @function
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  GeometryUpdater.prototype.createOutlineGeometryInstance =
    DeveloperError.throwInstantiationError;

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  GeometryUpdater.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys and resources used by the object.  Once an object is destroyed, it should not be used.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  GeometryUpdater.prototype.destroy = function () {
    destroyObject(this);
  };
  /**
   * @param {Entity} entity
   * @param {Object} geometry
   * @private
   */
  GeometryUpdater.prototype._isHidden = function (entity, geometry) {
    var show = geometry.show;
    return (
      defined(show) && show.isConstant && !show.getValue(Iso8601.MINIMUM_VALUE)
    );
  };

  /**
   * @param {Entity} entity
   * @param {Object} geometry
   * @private
   */
  GeometryUpdater.prototype._isOnTerrain = function (entity, geometry) {
    return false;
  };

  /**
   * @param {GeometryOptions} options
   * @private
   */
  GeometryUpdater.prototype._getIsClosed = function (options) {
    return true;
  };

  /**
   * @param {Entity} entity
   * @param {Object} geometry
   * @private
   */
  GeometryUpdater.prototype._isDynamic = DeveloperError.throwInstantiationError;

  /**
   * @param {Entity} entity
   * @param {Object} geometry
   * @private
   */
  GeometryUpdater.prototype._setStaticOptions =
    DeveloperError.throwInstantiationError;

  /**
   * @param {Entity} entity
   * @param {String} propertyName
   * @param {*} newValue
   * @param {*} oldValue
   * @private
   */
  GeometryUpdater.prototype._onEntityPropertyChanged = function (
    entity,
    propertyName,
    newValue,
    oldValue
  ) {
    if (this._observedPropertyNames.indexOf(propertyName) === -1) {
      return;
    }

    var geometry = this._entity[this._geometryPropertyName];

    if (!defined(geometry)) {
      if (this._fillEnabled || this._outlineEnabled) {
        this._fillEnabled = false;
        this._outlineEnabled = false;
        this._geometryChanged.raiseEvent(this);
      }
      return;
    }

    var fillProperty = geometry.fill;
    var fillEnabled =
      defined(fillProperty) && fillProperty.isConstant
        ? fillProperty.getValue(Iso8601.MINIMUM_VALUE)
        : true;

    var outlineProperty = geometry.outline;
    var outlineEnabled = defined(outlineProperty);
    if (outlineEnabled && outlineProperty.isConstant) {
      outlineEnabled = outlineProperty.getValue(Iso8601.MINIMUM_VALUE);
    }

    if (!fillEnabled && !outlineEnabled) {
      if (this._fillEnabled || this._outlineEnabled) {
        this._fillEnabled = false;
        this._outlineEnabled = false;
        this._geometryChanged.raiseEvent(this);
      }
      return;
    }

    var show = geometry.show;
    if (this._isHidden(entity, geometry)) {
      if (this._fillEnabled || this._outlineEnabled) {
        this._fillEnabled = false;
        this._outlineEnabled = false;
        this._geometryChanged.raiseEvent(this);
      }
      return;
    }

    this._materialProperty = defaultValue(geometry.material, defaultMaterial);
    this._fillProperty = defaultValue(fillProperty, defaultFill);
    this._showProperty = defaultValue(show, defaultShow);
    this._showOutlineProperty = defaultValue(geometry.outline, defaultOutline);
    this._outlineColorProperty = outlineEnabled
      ? defaultValue(geometry.outlineColor, defaultOutlineColor)
      : undefined;
    this._shadowsProperty = defaultValue(geometry.shadows, defaultShadows);
    this._distanceDisplayConditionProperty = defaultValue(
      geometry.distanceDisplayCondition,
      defaultDistanceDisplayCondition
    );
    this._classificationTypeProperty = defaultValue(
      geometry.classificationType,
      defaultClassificationType
    );

    this._fillEnabled = fillEnabled;

    var onTerrain =
      this._isOnTerrain(entity, geometry) &&
      (this._supportsMaterialsforEntitiesOnTerrain ||
        this._materialProperty instanceof ColorMaterialProperty);

    if (outlineEnabled && onTerrain) {
      oneTimeWarning(oneTimeWarning.geometryOutlines);
      outlineEnabled = false;
    }

    this._onTerrain = onTerrain;
    this._outlineEnabled = outlineEnabled;

    if (this._isDynamic(entity, geometry)) {
      if (!this._dynamic) {
        this._dynamic = true;
        this._geometryChanged.raiseEvent(this);
      }
    } else {
      this._setStaticOptions(entity, geometry);
      this._isClosed = this._getIsClosed(this._options);
      var outlineWidth = geometry.outlineWidth;
      this._outlineWidth = defined(outlineWidth)
        ? outlineWidth.getValue(Iso8601.MINIMUM_VALUE)
        : 1.0;
      this._dynamic = false;
      this._geometryChanged.raiseEvent(this);
    }
  };

  /**
   * Creates the dynamic updater to be used when GeometryUpdater#isDynamic is true.
   *
   * @param {PrimitiveCollection} primitives The primitive collection to use.
   * @param {PrimitiveCollection} [groundPrimitives] The primitive collection to use for ground primitives.
   *
   * @returns {DynamicGeometryUpdater} The dynamic updater used to update the geometry each frame.
   *
   * @exception {DeveloperError} This instance does not represent dynamic geometry.
   * @private
   */
  GeometryUpdater.prototype.createDynamicUpdater = function (
    primitives,
    groundPrimitives
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("primitives", primitives);
    Check.defined("groundPrimitives", groundPrimitives);

    if (!this._dynamic) {
      throw new DeveloperError(
        "This instance does not represent dynamic geometry."
      );
    }
    //>>includeEnd('debug');

    return new this.constructor.DynamicGeometryUpdater(
      this,
      primitives,
      groundPrimitives
    );
  };

  /**
   * A {@link Property} whose value is lazily evaluated by a callback function.
   *
   * @alias CallbackProperty
   * @constructor
   *
   * @param {CallbackProperty.Callback} callback The function to be called when the property is evaluated.
   * @param {Boolean} isConstant <code>true</code> when the callback function returns the same value every time, <code>false</code> if the value will change.
   */
  function CallbackProperty(callback, isConstant) {
    this._callback = undefined;
    this._isConstant = undefined;
    this._definitionChanged = new Event();
    this.setCallback(callback, isConstant);
  }

  Object.defineProperties(CallbackProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.
     * @memberof CallbackProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._isConstant;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setCallback is called.
     * @memberof CallbackProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
  });

  /**
   * Gets the value of the property.
   *
   * @param {JulianDate} [time] The time for which to retrieve the value.  This parameter is unused since the value does not change with respect to time.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied or is unsupported.
   */
  CallbackProperty.prototype.getValue = function (time, result) {
    return this._callback(time, result);
  };

  /**
   * Sets the callback to be used.
   *
   * @param {CallbackProperty.Callback} callback The function to be called when the property is evaluated.
   * @param {Boolean} isConstant <code>true</code> when the callback function returns the same value every time, <code>false</code> if the value will change.
   */
  CallbackProperty.prototype.setCallback = function (callback, isConstant) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(callback)) {
      throw new DeveloperError("callback is required.");
    }
    if (!defined(isConstant)) {
      throw new DeveloperError("isConstant is required.");
    }
    //>>includeEnd('debug');

    var changed = this._callback !== callback || this._isConstant !== isConstant;

    this._callback = callback;
    this._isConstant = isConstant;

    if (changed) {
      this._definitionChanged.raiseEvent(this);
    }
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  CallbackProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof CallbackProperty &&
        this._callback === other._callback &&
        this._isConstant === other._isConstant)
    );
  };

  var scratchPosition$5 = new Cartesian3();
  var scratchCarto = new Cartographic();

  /**
   * @private
   */
  function TerrainOffsetProperty(
    scene,
    positionProperty,
    heightReferenceProperty,
    extrudedHeightReferenceProperty
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("scene", scene);
    Check.defined("positionProperty", positionProperty);
    //>>includeEnd('debug');

    this._scene = scene;
    this._heightReference = heightReferenceProperty;
    this._extrudedHeightReference = extrudedHeightReferenceProperty;
    this._positionProperty = positionProperty;

    this._position = new Cartesian3();
    this._cartographicPosition = new Cartographic();
    this._normal = new Cartesian3();

    this._definitionChanged = new Event();
    this._terrainHeight = 0;
    this._removeCallbackFunc = undefined;
    this._removeEventListener = undefined;
    this._removeModeListener = undefined;

    var that = this;
    if (defined(scene.globe)) {
      this._removeEventListener = scene.terrainProviderChanged.addEventListener(
        function () {
          that._updateClamping();
        }
      );
      this._removeModeListener = scene.morphComplete.addEventListener(
        function () {
          that._updateClamping();
        }
      );
    }

    if (positionProperty.isConstant) {
      var position = positionProperty.getValue(
        Iso8601.MINIMUM_VALUE,
        scratchPosition$5
      );
      if (
        !defined(position) ||
        Cartesian3.equals(position, Cartesian3.ZERO) ||
        !defined(scene.globe)
      ) {
        return;
      }
      this._position = Cartesian3.clone(position, this._position);

      this._updateClamping();

      this._normal = scene.globe.ellipsoid.geodeticSurfaceNormal(
        position,
        this._normal
      );
    }
  }

  Object.defineProperties(TerrainOffsetProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.
     * @memberof TerrainOffsetProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return false;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * @memberof TerrainOffsetProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
  });

  /**
   * @private
   */
  TerrainOffsetProperty.prototype._updateClamping = function () {
    if (defined(this._removeCallbackFunc)) {
      this._removeCallbackFunc();
    }

    var scene = this._scene;
    var globe = scene.globe;
    var position = this._position;

    if (!defined(globe) || Cartesian3.equals(position, Cartesian3.ZERO)) {
      this._terrainHeight = 0;
      return;
    }
    var ellipsoid = globe.ellipsoid;
    var surface = globe._surface;

    var that = this;
    var cartographicPosition = ellipsoid.cartesianToCartographic(
      position,
      this._cartographicPosition
    );
    var height = globe.getHeight(cartographicPosition);
    if (defined(height)) {
      this._terrainHeight = height;
    } else {
      this._terrainHeight = 0;
    }

    function updateFunction(clampedPosition) {
      if (scene.mode === SceneMode$1.SCENE3D) {
        var carto = ellipsoid.cartesianToCartographic(
          clampedPosition,
          scratchCarto
        );
        that._terrainHeight = carto.height;
      } else {
        that._terrainHeight = clampedPosition.x;
      }
      that.definitionChanged.raiseEvent();
    }
    this._removeCallbackFunc = surface.updateHeight(
      cartographicPosition,
      updateFunction
    );
  };

  /**
   * Gets the height relative to the terrain based on the positions.
   *
   * @returns {Cartesian3} The offset
   */
  TerrainOffsetProperty.prototype.getValue = function (time, result) {
    var heightReference = Property.getValueOrDefault(
      this._heightReference,
      time,
      HeightReference$1.NONE
    );
    var extrudedHeightReference = Property.getValueOrDefault(
      this._extrudedHeightReference,
      time,
      HeightReference$1.NONE
    );

    if (
      heightReference === HeightReference$1.NONE &&
      extrudedHeightReference !== HeightReference$1.RELATIVE_TO_GROUND
    ) {
      this._position = Cartesian3.clone(Cartesian3.ZERO, this._position);
      return Cartesian3.clone(Cartesian3.ZERO, result);
    }

    if (this._positionProperty.isConstant) {
      return Cartesian3.multiplyByScalar(
        this._normal,
        this._terrainHeight,
        result
      );
    }

    var scene = this._scene;
    var position = this._positionProperty.getValue(time, scratchPosition$5);
    if (
      !defined(position) ||
      Cartesian3.equals(position, Cartesian3.ZERO) ||
      !defined(scene.globe)
    ) {
      return Cartesian3.clone(Cartesian3.ZERO, result);
    }

    if (
      Cartesian3.equalsEpsilon(this._position, position, CesiumMath.EPSILON10)
    ) {
      return Cartesian3.multiplyByScalar(
        this._normal,
        this._terrainHeight,
        result
      );
    }

    this._position = Cartesian3.clone(position, this._position);

    this._updateClamping();

    var normal = scene.globe.ellipsoid.geodeticSurfaceNormal(
      position,
      this._normal
    );
    return Cartesian3.multiplyByScalar(normal, this._terrainHeight, result);
  };

  TerrainOffsetProperty.prototype.isDestroyed = function () {
    return false;
  };

  TerrainOffsetProperty.prototype.destroy = function () {
    if (defined(this._removeEventListener)) {
      this._removeEventListener();
    }
    if (defined(this._removeModeListener)) {
      this._removeModeListener();
    }
    if (defined(this._removeCallbackFunc)) {
      this._removeCallbackFunc();
    }
    return destroyObject(this);
  };

  function heightReferenceOnEntityPropertyChanged(
    entity,
    propertyName,
    newValue,
    oldValue
  ) {
    GeometryUpdater.prototype._onEntityPropertyChanged.call(
      this,
      entity,
      propertyName,
      newValue,
      oldValue
    );
    if (this._observedPropertyNames.indexOf(propertyName) === -1) {
      return;
    }

    var geometry = this._entity[this._geometryPropertyName];
    if (!defined(geometry)) {
      return;
    }

    if (defined(this._terrainOffsetProperty)) {
      this._terrainOffsetProperty.destroy();
      this._terrainOffsetProperty = undefined;
    }

    var heightReferenceProperty = geometry.heightReference;

    if (defined(heightReferenceProperty)) {
      var centerPosition = new CallbackProperty(
        this._computeCenter.bind(this),
        !this._dynamic
      );
      this._terrainOffsetProperty = new TerrainOffsetProperty(
        this._scene,
        centerPosition,
        heightReferenceProperty
      );
    }
  }

  var defaultOffset = Cartesian3.ZERO;

  var offsetScratch$3 = new Cartesian3();
  var positionScratch$6 = new Cartesian3();
  var scratchColor = new Color();

  function BoxGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.dimensions = undefined;
    this.offsetAttribute = undefined;
  }

  /**
   * A {@link GeometryUpdater} for boxes.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias BoxGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function BoxGeometryUpdater(entity, scene) {
    GeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new BoxGeometryOptions(entity),
      geometryPropertyName: "box",
      observedPropertyNames: ["availability", "position", "orientation", "box"],
    });

    this._onEntityPropertyChanged(entity, "box", entity.box, undefined);
  }

  if (defined(Object.create)) {
    BoxGeometryUpdater.prototype = Object.create(GeometryUpdater.prototype);
    BoxGeometryUpdater.prototype.constructor = BoxGeometryUpdater;
  }

  Object.defineProperties(BoxGeometryUpdater.prototype, {
    /**
     * Gets the terrain offset property
     * @type {TerrainOffsetProperty}
     * @memberof BoxGeometryUpdater.prototype
     * @readonly
     * @private
     */
    terrainOffsetProperty: {
      get: function () {
        return this._terrainOffsetProperty;
      },
    },
  });

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  BoxGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var show = new ShowGeometryInstanceAttribute(
      isAvailable &&
        entity.isShowing &&
        this._showProperty.getValue(time) &&
        this._fillProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );

    var attributes = {
      show: show,
      distanceDisplayCondition: distanceDisplayConditionAttribute,
      color: undefined,
      offset: undefined,
    };
    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }
    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset,
          offsetScratch$3
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: BoxGeometry.fromDimensions(this._options),
      modelMatrix: entity.computeModelMatrixForHeightReference(
        time,
        entity.box.heightReference,
        this._options.dimensions.z * 0.5,
        this._scene.mapProjection.ellipsoid
      ),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  BoxGeometryUpdater.prototype.createOutlineGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        distanceDisplayCondition
      ),
      offset: undefined,
    };
    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset,
          offsetScratch$3
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: BoxOutlineGeometry.fromDimensions(this._options),
      modelMatrix: entity.computeModelMatrixForHeightReference(
        time,
        entity.box.heightReference,
        this._options.dimensions.z * 0.5,
        this._scene.mapProjection.ellipsoid
      ),
      attributes: attributes,
    });
  };

  BoxGeometryUpdater.prototype._computeCenter = function (time, result) {
    return Property.getValueOrUndefined(this._entity.position, time, result);
  };

  BoxGeometryUpdater.prototype._isHidden = function (entity, box) {
    return (
      !defined(box.dimensions) ||
      !defined(entity.position) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, box)
    );
  };

  BoxGeometryUpdater.prototype._isDynamic = function (entity, box) {
    return (
      !entity.position.isConstant ||
      !Property.isConstant(entity.orientation) ||
      !box.dimensions.isConstant ||
      !Property.isConstant(box.outlineWidth)
    );
  };

  BoxGeometryUpdater.prototype._setStaticOptions = function (entity, box) {
    var heightReference = Property.getValueOrDefault(
      box.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );

    var options = this._options;
    options.vertexFormat =
      this._materialProperty instanceof ColorMaterialProperty
        ? PerInstanceColorAppearance.VERTEX_FORMAT
        : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.dimensions = box.dimensions.getValue(
      Iso8601.MINIMUM_VALUE,
      options.dimensions
    );
    options.offsetAttribute =
      heightReference !== HeightReference$1.NONE
        ? GeometryOffsetAttribute$1.ALL
        : undefined;
  };

  BoxGeometryUpdater.prototype._onEntityPropertyChanged = heightReferenceOnEntityPropertyChanged;

  BoxGeometryUpdater.DynamicGeometryUpdater = DynamicBoxGeometryUpdater;

  /**
   * @private
   */
  function DynamicBoxGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicBoxGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicBoxGeometryUpdater.prototype.constructor = DynamicBoxGeometryUpdater;
  }

  DynamicBoxGeometryUpdater.prototype._isHidden = function (entity, box, time) {
    var position = Property.getValueOrUndefined(
      entity.position,
      time,
      positionScratch$6
    );
    var dimensions = this._options.dimensions;
    return (
      !defined(position) ||
      !defined(dimensions) ||
      DynamicGeometryUpdater.prototype._isHidden.call(this, entity, box, time)
    );
  };

  DynamicBoxGeometryUpdater.prototype._setOptions = function (entity, box, time) {
    var heightReference = Property.getValueOrDefault(
      box.heightReference,
      time,
      HeightReference$1.NONE
    );
    var options = this._options;
    options.dimensions = Property.getValueOrUndefined(
      box.dimensions,
      time,
      options.dimensions
    );
    options.offsetAttribute =
      heightReference !== HeightReference$1.NONE
        ? GeometryOffsetAttribute$1.ALL
        : undefined;
  };

  /**
   * Represents a command to the renderer for clearing a framebuffer.
   *
   * @private
   * @constructor
   */
  function ClearCommand(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The value to clear the color buffer to.  When <code>undefined</code>, the color buffer is not cleared.
     *
     * @type {Color}
     *
     * @default undefined
     */
    this.color = options.color;

    /**
     * The value to clear the depth buffer to.  When <code>undefined</code>, the depth buffer is not cleared.
     *
     * @type {Number}
     *
     * @default undefined
     */
    this.depth = options.depth;

    /**
     * The value to clear the stencil buffer to.  When <code>undefined</code>, the stencil buffer is not cleared.
     *
     * @type {Number}
     *
     * @default undefined
     */
    this.stencil = options.stencil;

    /**
     * The render state to apply when executing the clear command.  The following states affect clearing:
     * scissor test, color mask, depth mask, and stencil mask.  When the render state is
     * <code>undefined</code>, the default render state is used.
     *
     * @type {RenderState}
     *
     * @default undefined
     */
    this.renderState = options.renderState;

    /**
     * The framebuffer to clear.
     *
     * @type {Framebuffer}
     *
     * @default undefined
     */
    this.framebuffer = options.framebuffer;

    /**
     * The object who created this command.  This is useful for debugging command
     * execution; it allows you to see who created a command when you only have a
     * reference to the command, and can be used to selectively execute commands
     * with {@link Scene#debugCommandFilter}.
     *
     * @type {Object}
     *
     * @default undefined
     *
     * @see Scene#debugCommandFilter
     */
    this.owner = options.owner;

    /**
     * The pass in which to run this command.
     *
     * @type {Pass}
     *
     * @default undefined
     */
    this.pass = options.pass;
  }

  /**
   * Clears color to (0.0, 0.0, 0.0, 0.0); depth to 1.0; and stencil to 0.
   *
   * @type {ClearCommand}
   *
   * @constant
   */
  ClearCommand.ALL = Object.freeze(
    new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 0.0),
      depth: 1.0,
      stencil: 0.0,
    })
  );

  ClearCommand.prototype.execute = function (context, passState) {
    context.clear(this, passState);
  };

  /**
   * An enum describing the x, y, and z axes and helper conversion functions.
   *
   * @enum {Number}
   */
  var Axis = {
    /**
     * Denotes the x-axis.
     *
     * @type {Number}
     * @constant
     */
    X: 0,

    /**
     * Denotes the y-axis.
     *
     * @type {Number}
     * @constant
     */
    Y: 1,

    /**
     * Denotes the z-axis.
     *
     * @type {Number}
     * @constant
     */
    Z: 2,
  };

  /**
   * Matrix used to convert from y-up to z-up
   *
   * @type {Matrix4}
   * @constant
   */
  Axis.Y_UP_TO_Z_UP = Matrix4.fromRotationTranslation(
    Matrix3.fromRotationX(CesiumMath.PI_OVER_TWO)
  );

  /**
   * Matrix used to convert from z-up to y-up
   *
   * @type {Matrix4}
   * @constant
   */
  Axis.Z_UP_TO_Y_UP = Matrix4.fromRotationTranslation(
    Matrix3.fromRotationX(-CesiumMath.PI_OVER_TWO)
  );

  /**
   * Matrix used to convert from x-up to z-up
   *
   * @type {Matrix4}
   * @constant
   */
  Axis.X_UP_TO_Z_UP = Matrix4.fromRotationTranslation(
    Matrix3.fromRotationY(-CesiumMath.PI_OVER_TWO)
  );

  /**
   * Matrix used to convert from z-up to x-up
   *
   * @type {Matrix4}
   * @constant
   */
  Axis.Z_UP_TO_X_UP = Matrix4.fromRotationTranslation(
    Matrix3.fromRotationY(CesiumMath.PI_OVER_TWO)
  );

  /**
   * Matrix used to convert from x-up to y-up
   *
   * @type {Matrix4}
   * @constant
   */
  Axis.X_UP_TO_Y_UP = Matrix4.fromRotationTranslation(
    Matrix3.fromRotationZ(CesiumMath.PI_OVER_TWO)
  );

  /**
   * Matrix used to convert from y-up to x-up
   *
   * @type {Matrix4}
   * @constant
   */
  Axis.Y_UP_TO_X_UP = Matrix4.fromRotationTranslation(
    Matrix3.fromRotationZ(-CesiumMath.PI_OVER_TWO)
  );

  /**
   * Gets the axis by name
   *
   * @param {String} name The name of the axis.
   * @returns {Number} The axis enum.
   */
  Axis.fromName = function (name) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("name", name);
    //>>includeEnd('debug');

    return Axis[name];
  };

  var Axis$1 = Object.freeze(Axis);

  /**
   * An enum describing the attribute type for glTF and 3D Tiles.
   *
   * @enum {String}
   *
   * @private
   */
  var AttributeType = {
    /**
     * The attribute is a single component.
     *
     * @type {String}
     * @constant
     */
    SCALAR: "SCALAR",

    /**
     * The attribute is a two-component vector.
     *
     * @type {String}
     * @constant
     */
    VEC2: "VEC2",

    /**
     * The attribute is a three-component vector.
     *
     * @type {String}
     * @constant
     */
    VEC3: "VEC3",

    /**
     * The attribute is a four-component vector.
     *
     * @type {String}
     * @constant
     */
    VEC4: "VEC4",

    /**
     * The attribute is a 2x2 matrix.
     *
     * @type {String}
     * @constant
     */
    MAT2: "MAT2",

    /**
     * The attribute is a 3x3 matrix.
     *
     * @type {String}
     * @constant
     */
    MAT3: "MAT3",

    /**
     * The attribute is a 4x4 matrix.
     *
     * @type {String}
     * @constant
     */
    MAT4: "MAT4",
  };
  var AttributeType$1 = Object.freeze(AttributeType);

  /**
   * Defines how per-feature colors set from the Cesium API or declarative styling blend with the source colors from
   * the original feature, e.g. glTF material or per-point color in the tile.
   * <p>
   * When <code>REPLACE</code> or <code>MIX</code> are used and the source color is a glTF material, the technique must assign the
   * <code>_3DTILESDIFFUSE</code> semantic to the diffuse color parameter. Otherwise only <code>HIGHLIGHT</code> is supported.
   * </p>
   * <p>
   * A feature whose color evaluates to white (1.0, 1.0, 1.0) is always rendered without color blending, regardless of the
   * tileset's color blend mode.
   * </p>
   * <pre><code>
   * "techniques": {
   *   "technique0": {
   *     "parameters": {
   *       "diffuse": {
   *         "semantic": "_3DTILESDIFFUSE",
   *         "type": 35666
   *       }
   *     }
   *   }
   * }
   * </code></pre>
   *
   * @enum {Number}
   */
  var Cesium3DTileColorBlendMode = {
    /**
     * Multiplies the source color by the feature color.
     *
     * @type {Number}
     * @constant
     */
    HIGHLIGHT: 0,

    /**
     * Replaces the source color with the feature color.
     *
     * @type {Number}
     * @constant
     */
    REPLACE: 1,

    /**
     * Blends the source color and feature color together.
     *
     * @type {Number}
     * @constant
     */
    MIX: 2,
  };
  var Cesium3DTileColorBlendMode$1 = Object.freeze(Cesium3DTileColorBlendMode);

  var ComponentsPerAttribute = {
    SCALAR: 1,
    VEC2: 2,
    VEC3: 3,
    VEC4: 4,
    MAT2: 4,
    MAT3: 9,
    MAT4: 16,
  };

  var ClassPerType = {
    SCALAR: undefined,
    VEC2: Cartesian2,
    VEC3: Cartesian3,
    VEC4: Cartesian4,
    MAT2: Matrix2,
    MAT3: Matrix3,
    MAT4: Matrix4,
  };

  /**
   * @private
   */
  function getBinaryAccessor(accessor) {
    var componentType = accessor.componentType;
    var componentDatatype;
    if (typeof componentType === "string") {
      componentDatatype = ComponentDatatype$1.fromName(componentType);
    } else {
      componentDatatype = componentType;
    }

    var componentsPerAttribute = ComponentsPerAttribute[accessor.type];
    var classType = ClassPerType[accessor.type];
    return {
      componentsPerAttribute: componentsPerAttribute,
      classType: classType,
      createArrayBufferView: function (buffer, byteOffset, length) {
        return ComponentDatatype$1.createArrayBufferView(
          componentDatatype,
          buffer,
          byteOffset,
          componentsPerAttribute * length
        );
      },
    };
  }

  var DEFAULT_COLOR_VALUE = Color.WHITE;
  var DEFAULT_SHOW_VALUE = true;

  /**
   * @private
   * @constructor
   */
  function Cesium3DTileBatchTable(
    content,
    featuresLength,
    batchTableJson,
    batchTableBinary,
    colorChangedCallback
  ) {
    /**
     * @readonly
     */
    this.featuresLength = featuresLength;

    this._translucentFeaturesLength = 0; // Number of features in the tile that are translucent

    var extensions;
    if (defined(batchTableJson)) {
      extensions = batchTableJson.extensions;
    }
    this._extensions = defaultValue(extensions, {});

    var properties = initializeProperties(batchTableJson);
    this._properties = properties;

    this._batchTableHierarchy = initializeHierarchy(
      this,
      batchTableJson,
      batchTableBinary
    );
    this._batchTableBinaryProperties = getBinaryProperties(
      featuresLength,
      properties,
      batchTableBinary
    );

    // PERFORMANCE_IDEA: These parallel arrays probably generate cache misses in get/set color/show
    // and use A LOT of memory.  How can we use less memory?
    this._showAlphaProperties = undefined; // [Show (0 or 255), Alpha (0 to 255)] property for each feature
    this._batchValues = undefined; // Per-feature RGBA (A is based on the color's alpha and feature's show property)

    this._batchValuesDirty = false;
    this._batchTexture = undefined;
    this._defaultTexture = undefined;

    this._pickTexture = undefined;
    this._pickIds = [];

    this._content = content;

    this._colorChangedCallback = colorChangedCallback;

    // Dimensions for batch and pick textures
    var textureDimensions;
    var textureStep;

    if (featuresLength > 0) {
      // PERFORMANCE_IDEA: this can waste memory in the last row in the uncommon case
      // when more than one row is needed (e.g., > 16K features in one tile)
      var width = Math.min(featuresLength, ContextLimits.maximumTextureSize);
      var height = Math.ceil(featuresLength / ContextLimits.maximumTextureSize);
      var stepX = 1.0 / width;
      var centerX = stepX * 0.5;
      var stepY = 1.0 / height;
      var centerY = stepY * 0.5;

      textureDimensions = new Cartesian2(width, height);
      textureStep = new Cartesian4(stepX, centerX, stepY, centerY);
    }

    this._textureDimensions = textureDimensions;
    this._textureStep = textureStep;
  }

  // This can be overridden for testing purposes
  Cesium3DTileBatchTable._deprecationWarning = deprecationWarning;

  Object.defineProperties(Cesium3DTileBatchTable.prototype, {
    memorySizeInBytes: {
      get: function () {
        var memory = 0;
        if (defined(this._pickTexture)) {
          memory += this._pickTexture.sizeInBytes;
        }
        if (defined(this._batchTexture)) {
          memory += this._batchTexture.sizeInBytes;
        }
        return memory;
      },
    },
  });

  function initializeProperties(jsonHeader) {
    var properties = {};

    if (!defined(jsonHeader)) {
      return properties;
    }

    for (var propertyName in jsonHeader) {
      if (
        jsonHeader.hasOwnProperty(propertyName) &&
        propertyName !== "HIERARCHY" && // Deprecated HIERARCHY property
        propertyName !== "extensions" &&
        propertyName !== "extras"
      ) {
        properties[propertyName] = clone(jsonHeader[propertyName], true);
      }
    }

    return properties;
  }

  function initializeHierarchy(batchTable, jsonHeader, binaryBody) {
    if (!defined(jsonHeader)) {
      return;
    }

    var hierarchy = batchTable._extensions["3DTILES_batch_table_hierarchy"];

    var legacyHierarchy = jsonHeader.HIERARCHY;
    if (defined(legacyHierarchy)) {
      Cesium3DTileBatchTable._deprecationWarning(
        "batchTableHierarchyExtension",
        "The batch table HIERARCHY property has been moved to an extension. Use extensions.3DTILES_batch_table_hierarchy instead."
      );
      batchTable._extensions["3DTILES_batch_table_hierarchy"] = legacyHierarchy;
      hierarchy = legacyHierarchy;
    }

    if (!defined(hierarchy)) {
      return;
    }

    return initializeHierarchyValues(hierarchy, binaryBody);
  }

  function initializeHierarchyValues(hierarchyJson, binaryBody) {
    var i;
    var classId;
    var binaryAccessor;

    var instancesLength = hierarchyJson.instancesLength;
    var classes = hierarchyJson.classes;
    var classIds = hierarchyJson.classIds;
    var parentCounts = hierarchyJson.parentCounts;
    var parentIds = hierarchyJson.parentIds;
    var parentIdsLength = instancesLength;

    if (defined(classIds.byteOffset)) {
      classIds.componentType = defaultValue(
        classIds.componentType,
        ComponentDatatype$1.UNSIGNED_SHORT
      );
      classIds.type = AttributeType$1.SCALAR;
      binaryAccessor = getBinaryAccessor(classIds);
      classIds = binaryAccessor.createArrayBufferView(
        binaryBody.buffer,
        binaryBody.byteOffset + classIds.byteOffset,
        instancesLength
      );
    }

    var parentIndexes;
    if (defined(parentCounts)) {
      if (defined(parentCounts.byteOffset)) {
        parentCounts.componentType = defaultValue(
          parentCounts.componentType,
          ComponentDatatype$1.UNSIGNED_SHORT
        );
        parentCounts.type = AttributeType$1.SCALAR;
        binaryAccessor = getBinaryAccessor(parentCounts);
        parentCounts = binaryAccessor.createArrayBufferView(
          binaryBody.buffer,
          binaryBody.byteOffset + parentCounts.byteOffset,
          instancesLength
        );
      }
      parentIndexes = new Uint16Array(instancesLength);
      parentIdsLength = 0;
      for (i = 0; i < instancesLength; ++i) {
        parentIndexes[i] = parentIdsLength;
        parentIdsLength += parentCounts[i];
      }
    }

    if (defined(parentIds) && defined(parentIds.byteOffset)) {
      parentIds.componentType = defaultValue(
        parentIds.componentType,
        ComponentDatatype$1.UNSIGNED_SHORT
      );
      parentIds.type = AttributeType$1.SCALAR;
      binaryAccessor = getBinaryAccessor(parentIds);
      parentIds = binaryAccessor.createArrayBufferView(
        binaryBody.buffer,
        binaryBody.byteOffset + parentIds.byteOffset,
        parentIdsLength
      );
    }

    var classesLength = classes.length;
    for (i = 0; i < classesLength; ++i) {
      var classInstancesLength = classes[i].length;
      var properties = classes[i].instances;
      var binaryProperties = getBinaryProperties(
        classInstancesLength,
        properties,
        binaryBody
      );
      classes[i].instances = combine(binaryProperties, properties);
    }

    var classCounts = arrayFill(new Array(classesLength), 0);
    var classIndexes = new Uint16Array(instancesLength);
    for (i = 0; i < instancesLength; ++i) {
      classId = classIds[i];
      classIndexes[i] = classCounts[classId];
      ++classCounts[classId];
    }

    var hierarchy = {
      classes: classes,
      classIds: classIds,
      classIndexes: classIndexes,
      parentCounts: parentCounts,
      parentIndexes: parentIndexes,
      parentIds: parentIds,
    };

    //>>includeStart('debug', pragmas.debug);
    validateHierarchy(hierarchy);
    //>>includeEnd('debug');

    return hierarchy;
  }

  //>>includeStart('debug', pragmas.debug);
  var scratchValidateStack = [];
  function validateHierarchy(hierarchy) {
    var stack = scratchValidateStack;
    stack.length = 0;

    var classIds = hierarchy.classIds;
    var instancesLength = classIds.length;

    for (var i = 0; i < instancesLength; ++i) {
      validateInstance(hierarchy, i, stack);
    }
  }

  function validateInstance(hierarchy, instanceIndex, stack) {
    var parentCounts = hierarchy.parentCounts;
    var parentIds = hierarchy.parentIds;
    var parentIndexes = hierarchy.parentIndexes;
    var classIds = hierarchy.classIds;
    var instancesLength = classIds.length;

    if (!defined(parentIds)) {
      // No need to validate if there are no parents
      return;
    }

    if (instanceIndex >= instancesLength) {
      throw new DeveloperError(
        "Parent index " +
          instanceIndex +
          " exceeds the total number of instances: " +
          instancesLength
      );
    }
    if (stack.indexOf(instanceIndex) > -1) {
      throw new DeveloperError(
        "Circular dependency detected in the batch table hierarchy."
      );
    }

    stack.push(instanceIndex);
    var parentCount = defined(parentCounts) ? parentCounts[instanceIndex] : 1;
    var parentIndex = defined(parentCounts)
      ? parentIndexes[instanceIndex]
      : instanceIndex;
    for (var i = 0; i < parentCount; ++i) {
      var parentId = parentIds[parentIndex + i];
      // Stop the traversal when the instance has no parent (its parentId equals itself), else continue the traversal.
      if (parentId !== instanceIndex) {
        validateInstance(hierarchy, parentId, stack);
      }
    }
    stack.pop(instanceIndex);
  }
  //>>includeEnd('debug');

  function getBinaryProperties(featuresLength, properties, binaryBody) {
    var binaryProperties;
    for (var name in properties) {
      if (properties.hasOwnProperty(name)) {
        var property = properties[name];
        var byteOffset = property.byteOffset;
        if (defined(byteOffset)) {
          // This is a binary property
          var componentType = property.componentType;
          var type = property.type;
          if (!defined(componentType)) {
            throw new RuntimeError("componentType is required.");
          }
          if (!defined(type)) {
            throw new RuntimeError("type is required.");
          }
          if (!defined(binaryBody)) {
            throw new RuntimeError(
              "Property " + name + " requires a batch table binary."
            );
          }

          var binaryAccessor = getBinaryAccessor(property);
          var componentCount = binaryAccessor.componentsPerAttribute;
          var classType = binaryAccessor.classType;
          var typedArray = binaryAccessor.createArrayBufferView(
            binaryBody.buffer,
            binaryBody.byteOffset + byteOffset,
            featuresLength
          );

          if (!defined(binaryProperties)) {
            binaryProperties = {};
          }

          // Store any information needed to access the binary data, including the typed array,
          // componentCount (e.g. a VEC4 would be 4), and the type used to pack and unpack (e.g. Cartesian4).
          binaryProperties[name] = {
            typedArray: typedArray,
            componentCount: componentCount,
            type: classType,
          };
        }
      }
    }
    return binaryProperties;
  }

  Cesium3DTileBatchTable.getBinaryProperties = function (
    featuresLength,
    batchTableJson,
    batchTableBinary
  ) {
    return getBinaryProperties(featuresLength, batchTableJson, batchTableBinary);
  };

  function getByteLength(batchTable) {
    var dimensions = batchTable._textureDimensions;
    return dimensions.x * dimensions.y * 4;
  }

  function getBatchValues(batchTable) {
    if (!defined(batchTable._batchValues)) {
      // Default batch texture to RGBA = 255: white highlight (RGB) and show/alpha = true/255 (A).
      var byteLength = getByteLength(batchTable);
      var bytes = new Uint8Array(byteLength);
      arrayFill(bytes, 255);
      batchTable._batchValues = bytes;
    }

    return batchTable._batchValues;
  }

  function getShowAlphaProperties(batchTable) {
    if (!defined(batchTable._showAlphaProperties)) {
      var byteLength = 2 * batchTable.featuresLength;
      var bytes = new Uint8Array(byteLength);
      // [Show = true, Alpha = 255]
      arrayFill(bytes, 255);
      batchTable._showAlphaProperties = bytes;
    }
    return batchTable._showAlphaProperties;
  }

  function checkBatchId(batchId, featuresLength) {
    if (!defined(batchId) || batchId < 0 || batchId > featuresLength) {
      throw new DeveloperError(
        "batchId is required and between zero and featuresLength - 1 (" +
          featuresLength -
          +")."
      );
    }
  }

  Cesium3DTileBatchTable.prototype.setShow = function (batchId, show) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    Check.typeOf.bool("show", show);
    //>>includeEnd('debug');

    if (show && !defined(this._showAlphaProperties)) {
      // Avoid allocating since the default is show = true
      return;
    }

    var showAlphaProperties = getShowAlphaProperties(this);
    var propertyOffset = batchId * 2;

    var newShow = show ? 255 : 0;
    if (showAlphaProperties[propertyOffset] !== newShow) {
      showAlphaProperties[propertyOffset] = newShow;

      var batchValues = getBatchValues(this);

      // Compute alpha used in the shader based on show and color.alpha properties
      var offset = batchId * 4 + 3;
      batchValues[offset] = show ? showAlphaProperties[propertyOffset + 1] : 0;

      this._batchValuesDirty = true;
    }
  };

  Cesium3DTileBatchTable.prototype.setAllShow = function (show) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.bool("show", show);
    //>>includeEnd('debug');

    var featuresLength = this.featuresLength;
    for (var i = 0; i < featuresLength; ++i) {
      this.setShow(i, show);
    }
  };

  Cesium3DTileBatchTable.prototype.getShow = function (batchId) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    //>>includeEnd('debug');

    if (!defined(this._showAlphaProperties)) {
      // Avoid allocating since the default is show = true
      return true;
    }

    var offset = batchId * 2;
    return this._showAlphaProperties[offset] === 255;
  };

  var scratchColorBytes = new Array(4);

  Cesium3DTileBatchTable.prototype.setColor = function (batchId, color) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    Check.typeOf.object("color", color);
    //>>includeEnd('debug');

    if (Color.equals(color, DEFAULT_COLOR_VALUE) && !defined(this._batchValues)) {
      // Avoid allocating since the default is white
      return;
    }

    var newColor = color.toBytes(scratchColorBytes);
    var newAlpha = newColor[3];

    var batchValues = getBatchValues(this);
    var offset = batchId * 4;

    var showAlphaProperties = getShowAlphaProperties(this);
    var propertyOffset = batchId * 2;

    if (
      batchValues[offset] !== newColor[0] ||
      batchValues[offset + 1] !== newColor[1] ||
      batchValues[offset + 2] !== newColor[2] ||
      showAlphaProperties[propertyOffset + 1] !== newAlpha
    ) {
      batchValues[offset] = newColor[0];
      batchValues[offset + 1] = newColor[1];
      batchValues[offset + 2] = newColor[2];

      var wasTranslucent = showAlphaProperties[propertyOffset + 1] !== 255;

      // Compute alpha used in the shader based on show and color.alpha properties
      var show = showAlphaProperties[propertyOffset] !== 0;
      batchValues[offset + 3] = show ? newAlpha : 0;
      showAlphaProperties[propertyOffset + 1] = newAlpha;

      // Track number of translucent features so we know if this tile needs
      // opaque commands, translucent commands, or both for rendering.
      var isTranslucent = newAlpha !== 255;
      if (isTranslucent && !wasTranslucent) {
        ++this._translucentFeaturesLength;
      } else if (!isTranslucent && wasTranslucent) {
        --this._translucentFeaturesLength;
      }

      this._batchValuesDirty = true;

      if (defined(this._colorChangedCallback)) {
        this._colorChangedCallback(batchId, color);
      }
    }
  };

  Cesium3DTileBatchTable.prototype.setAllColor = function (color) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("color", color);
    //>>includeEnd('debug');

    var featuresLength = this.featuresLength;
    for (var i = 0; i < featuresLength; ++i) {
      this.setColor(i, color);
    }
  };

  Cesium3DTileBatchTable.prototype.getColor = function (batchId, result) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    if (!defined(this._batchValues)) {
      return Color.clone(DEFAULT_COLOR_VALUE, result);
    }

    var batchValues = this._batchValues;
    var offset = batchId * 4;

    var showAlphaProperties = this._showAlphaProperties;
    var propertyOffset = batchId * 2;

    return Color.fromBytes(
      batchValues[offset],
      batchValues[offset + 1],
      batchValues[offset + 2],
      showAlphaProperties[propertyOffset + 1],
      result
    );
  };

  Cesium3DTileBatchTable.prototype.getPickColor = function (batchId) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    //>>includeEnd('debug');
    return this._pickIds[batchId];
  };

  var scratchColor$1 = new Color();

  Cesium3DTileBatchTable.prototype.applyStyle = function (style) {
    if (!defined(style)) {
      this.setAllColor(DEFAULT_COLOR_VALUE);
      this.setAllShow(DEFAULT_SHOW_VALUE);
      return;
    }

    var content = this._content;
    var length = this.featuresLength;
    for (var i = 0; i < length; ++i) {
      var feature = content.getFeature(i);
      var color = defined(style.color)
        ? style.color.evaluateColor(feature, scratchColor$1)
        : DEFAULT_COLOR_VALUE;
      var show = defined(style.show)
        ? style.show.evaluate(feature)
        : DEFAULT_SHOW_VALUE;
      this.setColor(i, color);
      this.setShow(i, show);
    }
  };

  function getBinaryProperty(binaryProperty, index) {
    var typedArray = binaryProperty.typedArray;
    var componentCount = binaryProperty.componentCount;
    if (componentCount === 1) {
      return typedArray[index];
    }
    return binaryProperty.type.unpack(typedArray, index * componentCount);
  }

  function setBinaryProperty(binaryProperty, index, value) {
    var typedArray = binaryProperty.typedArray;
    var componentCount = binaryProperty.componentCount;
    if (componentCount === 1) {
      typedArray[index] = value;
    } else {
      binaryProperty.type.pack(value, typedArray, index * componentCount);
    }
  }

  // The size of this array equals the maximum instance count among all loaded tiles, which has the potential to be large.
  var scratchVisited = [];
  var scratchStack = [];
  var marker = 0;
  function traverseHierarchyMultipleParents(
    hierarchy,
    instanceIndex,
    endConditionCallback
  ) {
    var classIds = hierarchy.classIds;
    var parentCounts = hierarchy.parentCounts;
    var parentIds = hierarchy.parentIds;
    var parentIndexes = hierarchy.parentIndexes;
    var instancesLength = classIds.length;

    // Ignore instances that have already been visited. This occurs in diamond inheritance situations.
    // Use a marker value to indicate that an instance has been visited, which increments with each run.
    // This is more efficient than clearing the visited array every time.
    var visited = scratchVisited;
    visited.length = Math.max(visited.length, instancesLength);
    var visitedMarker = ++marker;

    var stack = scratchStack;
    stack.length = 0;
    stack.push(instanceIndex);

    while (stack.length > 0) {
      instanceIndex = stack.pop();
      if (visited[instanceIndex] === visitedMarker) {
        // This instance has already been visited, stop traversal
        continue;
      }
      visited[instanceIndex] = visitedMarker;
      var result = endConditionCallback(hierarchy, instanceIndex);
      if (defined(result)) {
        // The end condition was met, stop the traversal and return the result
        return result;
      }
      var parentCount = parentCounts[instanceIndex];
      var parentIndex = parentIndexes[instanceIndex];
      for (var i = 0; i < parentCount; ++i) {
        var parentId = parentIds[parentIndex + i];
        // Stop the traversal when the instance has no parent (its parentId equals itself)
        // else add the parent to the stack to continue the traversal.
        if (parentId !== instanceIndex) {
          stack.push(parentId);
        }
      }
    }
  }

  function traverseHierarchySingleParent(
    hierarchy,
    instanceIndex,
    endConditionCallback
  ) {
    var hasParent = true;
    while (hasParent) {
      var result = endConditionCallback(hierarchy, instanceIndex);
      if (defined(result)) {
        // The end condition was met, stop the traversal and return the result
        return result;
      }
      var parentId = hierarchy.parentIds[instanceIndex];
      hasParent = parentId !== instanceIndex;
      instanceIndex = parentId;
    }
  }

  function traverseHierarchy(hierarchy, instanceIndex, endConditionCallback) {
    // Traverse over the hierarchy and process each instance with the endConditionCallback.
    // When the endConditionCallback returns a value, the traversal stops and that value is returned.
    var parentCounts = hierarchy.parentCounts;
    var parentIds = hierarchy.parentIds;
    if (!defined(parentIds)) {
      return endConditionCallback(hierarchy, instanceIndex);
    } else if (defined(parentCounts)) {
      return traverseHierarchyMultipleParents(
        hierarchy,
        instanceIndex,
        endConditionCallback
      );
    }
    return traverseHierarchySingleParent(
      hierarchy,
      instanceIndex,
      endConditionCallback
    );
  }

  function hasPropertyInHierarchy(batchTable, batchId, name) {
    var hierarchy = batchTable._batchTableHierarchy;
    var result = traverseHierarchy(hierarchy, batchId, function (
      hierarchy,
      instanceIndex
    ) {
      var classId = hierarchy.classIds[instanceIndex];
      var instances = hierarchy.classes[classId].instances;
      if (defined(instances[name])) {
        return true;
      }
    });
    return defined(result);
  }

  function getPropertyNamesInHierarchy(batchTable, batchId, results) {
    var hierarchy = batchTable._batchTableHierarchy;
    traverseHierarchy(hierarchy, batchId, function (hierarchy, instanceIndex) {
      var classId = hierarchy.classIds[instanceIndex];
      var instances = hierarchy.classes[classId].instances;
      for (var name in instances) {
        if (instances.hasOwnProperty(name)) {
          if (results.indexOf(name) === -1) {
            results.push(name);
          }
        }
      }
    });
  }

  function getHierarchyProperty(batchTable, batchId, name) {
    var hierarchy = batchTable._batchTableHierarchy;
    return traverseHierarchy(hierarchy, batchId, function (
      hierarchy,
      instanceIndex
    ) {
      var classId = hierarchy.classIds[instanceIndex];
      var instanceClass = hierarchy.classes[classId];
      var indexInClass = hierarchy.classIndexes[instanceIndex];
      var propertyValues = instanceClass.instances[name];
      if (defined(propertyValues)) {
        if (defined(propertyValues.typedArray)) {
          return getBinaryProperty(propertyValues, indexInClass);
        }
        return clone(propertyValues[indexInClass], true);
      }
    });
  }

  function setHierarchyProperty(batchTable, batchId, name, value) {
    var hierarchy = batchTable._batchTableHierarchy;
    var result = traverseHierarchy(hierarchy, batchId, function (
      hierarchy,
      instanceIndex
    ) {
      var classId = hierarchy.classIds[instanceIndex];
      var instanceClass = hierarchy.classes[classId];
      var indexInClass = hierarchy.classIndexes[instanceIndex];
      var propertyValues = instanceClass.instances[name];
      if (defined(propertyValues)) {
        //>>includeStart('debug', pragmas.debug);
        if (instanceIndex !== batchId) {
          throw new DeveloperError(
            'Inherited property "' + name + '" is read-only.'
          );
        }
        //>>includeEnd('debug');
        if (defined(propertyValues.typedArray)) {
          setBinaryProperty(propertyValues, indexInClass, value);
        } else {
          propertyValues[indexInClass] = clone(value, true);
        }
        return true;
      }
    });
    return defined(result);
  }

  Cesium3DTileBatchTable.prototype.isClass = function (batchId, className) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    Check.typeOf.string("className", className);
    //>>includeEnd('debug');

    // PERFORMANCE_IDEA : cache results in the ancestor classes to speed up this check if this area becomes a hotspot
    var hierarchy = this._batchTableHierarchy;
    if (!defined(hierarchy)) {
      return false;
    }

    // PERFORMANCE_IDEA : treat class names as integers for faster comparisons
    var result = traverseHierarchy(hierarchy, batchId, function (
      hierarchy,
      instanceIndex
    ) {
      var classId = hierarchy.classIds[instanceIndex];
      var instanceClass = hierarchy.classes[classId];
      if (instanceClass.name === className) {
        return true;
      }
    });
    return defined(result);
  };

  Cesium3DTileBatchTable.prototype.isExactClass = function (batchId, className) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("className", className);
    //>>includeEnd('debug');

    return this.getExactClassName(batchId) === className;
  };

  Cesium3DTileBatchTable.prototype.getExactClassName = function (batchId) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    //>>includeEnd('debug');

    var hierarchy = this._batchTableHierarchy;
    if (!defined(hierarchy)) {
      return undefined;
    }
    var classId = hierarchy.classIds[batchId];
    var instanceClass = hierarchy.classes[classId];
    return instanceClass.name;
  };

  Cesium3DTileBatchTable.prototype.hasProperty = function (batchId, name) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    Check.typeOf.string("name", name);
    //>>includeEnd('debug');

    return (
      defined(this._properties[name]) ||
      (defined(this._batchTableHierarchy) &&
        hasPropertyInHierarchy(this, batchId, name))
    );
  };

  Cesium3DTileBatchTable.prototype.getPropertyNames = function (
    batchId,
    results
  ) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    //>>includeEnd('debug');

    results = defined(results) ? results : [];
    results.length = 0;

    var propertyNames = Object.keys(this._properties);
    results.push.apply(results, propertyNames);

    if (defined(this._batchTableHierarchy)) {
      getPropertyNamesInHierarchy(this, batchId, results);
    }

    return results;
  };

  Cesium3DTileBatchTable.prototype.getProperty = function (batchId, name) {
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, this.featuresLength);
    Check.typeOf.string("name", name);
    //>>includeEnd('debug');

    if (defined(this._batchTableBinaryProperties)) {
      var binaryProperty = this._batchTableBinaryProperties[name];
      if (defined(binaryProperty)) {
        return getBinaryProperty(binaryProperty, batchId);
      }
    }

    var propertyValues = this._properties[name];
    if (defined(propertyValues)) {
      return clone(propertyValues[batchId], true);
    }

    if (defined(this._batchTableHierarchy)) {
      var hierarchyProperty = getHierarchyProperty(this, batchId, name);
      if (defined(hierarchyProperty)) {
        return hierarchyProperty;
      }
    }

    return undefined;
  };

  Cesium3DTileBatchTable.prototype.setProperty = function (batchId, name, value) {
    var featuresLength = this.featuresLength;
    //>>includeStart('debug', pragmas.debug);
    checkBatchId(batchId, featuresLength);
    Check.typeOf.string("name", name);
    //>>includeEnd('debug');

    if (defined(this._batchTableBinaryProperties)) {
      var binaryProperty = this._batchTableBinaryProperties[name];
      if (defined(binaryProperty)) {
        setBinaryProperty(binaryProperty, batchId, value);
        return;
      }
    }

    if (defined(this._batchTableHierarchy)) {
      if (setHierarchyProperty(this, batchId, name, value)) {
        return;
      }
    }

    var propertyValues = this._properties[name];
    if (!defined(propertyValues)) {
      // Property does not exist. Create it.
      this._properties[name] = new Array(featuresLength);
      propertyValues = this._properties[name];
    }

    propertyValues[batchId] = clone(value, true);
  };

  function getGlslComputeSt$1(batchTable) {
    // GLSL batchId is zero-based: [0, featuresLength - 1]
    if (batchTable._textureDimensions.y === 1) {
      return (
        "uniform vec4 tile_textureStep; \n" +
        "vec2 computeSt(float batchId) \n" +
        "{ \n" +
        "    float stepX = tile_textureStep.x; \n" +
        "    float centerX = tile_textureStep.y; \n" +
        "    return vec2(centerX + (batchId * stepX), 0.5); \n" +
        "} \n"
      );
    }

    return (
      "uniform vec4 tile_textureStep; \n" +
      "uniform vec2 tile_textureDimensions; \n" +
      "vec2 computeSt(float batchId) \n" +
      "{ \n" +
      "    float stepX = tile_textureStep.x; \n" +
      "    float centerX = tile_textureStep.y; \n" +
      "    float stepY = tile_textureStep.z; \n" +
      "    float centerY = tile_textureStep.w; \n" +
      "    float xId = mod(batchId, tile_textureDimensions.x); \n" +
      "    float yId = floor(batchId / tile_textureDimensions.x); \n" +
      "    return vec2(centerX + (xId * stepX), centerY + (yId * stepY)); \n" +
      "} \n"
    );
  }

  Cesium3DTileBatchTable.prototype.getVertexShaderCallback = function (
    handleTranslucent,
    batchIdAttributeName,
    diffuseAttributeOrUniformName
  ) {
    if (this.featuresLength === 0) {
      return;
    }

    var that = this;
    return function (source) {
      // If the color blend mode is HIGHLIGHT, the highlight color will always be applied in the fragment shader.
      // No need to apply the highlight color in the vertex shader as well.
      var renamedSource = modifyDiffuse(
        source,
        diffuseAttributeOrUniformName,
        false
      );
      var newMain;

      if (ContextLimits.maximumVertexTextureImageUnits > 0) {
        // When VTF is supported, perform per-feature show/hide in the vertex shader
        newMain = "";
        if (handleTranslucent) {
          newMain += "uniform bool tile_translucentCommand; \n";
        }
        newMain +=
          "uniform sampler2D tile_batchTexture; \n" +
          "varying vec4 tile_featureColor; \n" +
          "varying vec2 tile_featureSt; \n" +
          "void main() \n" +
          "{ \n" +
          "    vec2 st = computeSt(" +
          batchIdAttributeName +
          "); \n" +
          "    vec4 featureProperties = texture2D(tile_batchTexture, st); \n" +
          "    tile_color(featureProperties); \n" +
          "    float show = ceil(featureProperties.a); \n" + // 0 - false, non-zeo - true
          "    gl_Position *= show; \n"; // Per-feature show/hide
        if (handleTranslucent) {
          newMain +=
            "    bool isStyleTranslucent = (featureProperties.a != 1.0); \n" +
            "    if (czm_pass == czm_passTranslucent) \n" +
            "    { \n" +
            "        if (!isStyleTranslucent && !tile_translucentCommand) \n" + // Do not render opaque features in the translucent pass
            "        { \n" +
            "            gl_Position *= 0.0; \n" +
            "        } \n" +
            "    } \n" +
            "    else \n" +
            "    { \n" +
            "        if (isStyleTranslucent) \n" + // Do not render translucent features in the opaque pass
            "        { \n" +
            "            gl_Position *= 0.0; \n" +
            "        } \n" +
            "    } \n";
        }
        newMain +=
          "    tile_featureColor = featureProperties; \n" +
          "    tile_featureSt = st; \n" +
          "}";
      } else {
        // When VTF is not supported, color blend mode MIX will look incorrect due to the feature's color not being available in the vertex shader
        newMain =
          "varying vec2 tile_featureSt; \n" +
          "void main() \n" +
          "{ \n" +
          "    tile_color(vec4(1.0)); \n" +
          "    tile_featureSt = computeSt(" +
          batchIdAttributeName +
          "); \n" +
          "}";
      }

      return renamedSource + "\n" + getGlslComputeSt$1(that) + newMain;
    };
  };

  function getDefaultShader(source, applyHighlight) {
    source = ShaderSource.replaceMain(source, "tile_main");

    if (!applyHighlight) {
      return (
        source +
        "void tile_color(vec4 tile_featureColor) \n" +
        "{ \n" +
        "    tile_main(); \n" +
        "} \n"
      );
    }

    // The color blend mode is intended for the RGB channels so alpha is always just multiplied.
    // gl_FragColor is multiplied by the tile color only when tile_colorBlend is 0.0 (highlight)
    return (
      source +
      "uniform float tile_colorBlend; \n" +
      "void tile_color(vec4 tile_featureColor) \n" +
      "{ \n" +
      "    tile_main(); \n" +
      "    tile_featureColor = czm_gammaCorrect(tile_featureColor); \n" +
      "    gl_FragColor.a *= tile_featureColor.a; \n" +
      "    float highlight = ceil(tile_colorBlend); \n" +
      "    gl_FragColor.rgb *= mix(tile_featureColor.rgb, vec3(1.0), highlight); \n" +
      "} \n"
    );
  }

  function replaceDiffuseTextureCalls(source, diffuseAttributeOrUniformName) {
    var functionCall = "texture2D(" + diffuseAttributeOrUniformName;

    var fromIndex = 0;
    var startIndex = source.indexOf(functionCall, fromIndex);
    var endIndex;

    while (startIndex > -1) {
      var nestedLevel = 0;
      for (var i = startIndex; i < source.length; ++i) {
        var character = source.charAt(i);
        if (character === "(") {
          ++nestedLevel;
        } else if (character === ")") {
          --nestedLevel;
          if (nestedLevel === 0) {
            endIndex = i + 1;
            break;
          }
        }
      }
      var extractedFunction = source.slice(startIndex, endIndex);
      var replacedFunction =
        "tile_diffuse_final(" + extractedFunction + ", tile_diffuse)";

      source =
        source.slice(0, startIndex) + replacedFunction + source.slice(endIndex);
      fromIndex = startIndex + replacedFunction.length;
      startIndex = source.indexOf(functionCall, fromIndex);
    }

    return source;
  }

  function modifyDiffuse(source, diffuseAttributeOrUniformName, applyHighlight) {
    // If the glTF does not specify the _3DTILESDIFFUSE semantic, return the default shader.
    // Otherwise if _3DTILESDIFFUSE is defined prefer the shader below that can switch the color mode at runtime.
    if (!defined(diffuseAttributeOrUniformName)) {
      return getDefaultShader(source, applyHighlight);
    }

    // Find the diffuse uniform. Examples matches:
    //   uniform vec3 u_diffuseColor;
    //   uniform sampler2D diffuseTexture;
    var regex = new RegExp(
      "(uniform|attribute|in)\\s+(vec[34]|sampler2D)\\s+" +
        diffuseAttributeOrUniformName +
        ";"
    );
    var uniformMatch = source.match(regex);

    if (!defined(uniformMatch)) {
      // Could not find uniform declaration of type vec3, vec4, or sampler2D
      return getDefaultShader(source, applyHighlight);
    }

    var declaration = uniformMatch[0];
    var type = uniformMatch[2];

    source = ShaderSource.replaceMain(source, "tile_main");
    source = source.replace(declaration, ""); // Remove uniform declaration for now so the replace below doesn't affect it

    // If the tile color is white, use the source color. This implies the feature has not been styled.
    // Highlight: tile_colorBlend is 0.0 and the source color is used
    // Replace: tile_colorBlend is 1.0 and the tile color is used
    // Mix: tile_colorBlend is between 0.0 and 1.0, causing the source color and tile color to mix
    var finalDiffuseFunction =
      "bool isWhite(vec3 color) \n" +
      "{ \n" +
      "    return all(greaterThan(color, vec3(1.0 - czm_epsilon3))); \n" +
      "} \n" +
      "vec4 tile_diffuse_final(vec4 sourceDiffuse, vec4 tileDiffuse) \n" +
      "{ \n" +
      "    vec4 blendDiffuse = mix(sourceDiffuse, tileDiffuse, tile_colorBlend); \n" +
      "    vec4 diffuse = isWhite(tileDiffuse.rgb) ? sourceDiffuse : blendDiffuse; \n" +
      "    return vec4(diffuse.rgb, sourceDiffuse.a); \n" +
      "} \n";

    // The color blend mode is intended for the RGB channels so alpha is always just multiplied.
    // gl_FragColor is multiplied by the tile color only when tile_colorBlend is 0.0 (highlight)
    var highlight =
      "    tile_featureColor = czm_gammaCorrect(tile_featureColor); \n" +
      "    gl_FragColor.a *= tile_featureColor.a; \n" +
      "    float highlight = ceil(tile_colorBlend); \n" +
      "    gl_FragColor.rgb *= mix(tile_featureColor.rgb, vec3(1.0), highlight); \n";

    var setColor;
    if (type === "vec3" || type === "vec4") {
      var sourceDiffuse =
        type === "vec3"
          ? "vec4(" + diffuseAttributeOrUniformName + ", 1.0)"
          : diffuseAttributeOrUniformName;
      var replaceDiffuse = type === "vec3" ? "tile_diffuse.xyz" : "tile_diffuse";
      regex = new RegExp(diffuseAttributeOrUniformName, "g");
      source = source.replace(regex, replaceDiffuse);
      setColor =
        "    vec4 source = " +
        sourceDiffuse +
        "; \n" +
        "    tile_diffuse = tile_diffuse_final(source, tile_featureColor); \n" +
        "    tile_main(); \n";
    } else if (type === "sampler2D") {
      // Handles any number of nested parentheses
      // E.g. texture2D(u_diffuse, uv)
      // E.g. texture2D(u_diffuse, computeUV(index))
      source = replaceDiffuseTextureCalls(source, diffuseAttributeOrUniformName);
      setColor =
        "    tile_diffuse = tile_featureColor; \n" + "    tile_main(); \n";
    }

    source =
      "uniform float tile_colorBlend; \n" +
      "vec4 tile_diffuse = vec4(1.0); \n" +
      finalDiffuseFunction +
      declaration +
      "\n" +
      source +
      "\n" +
      "void tile_color(vec4 tile_featureColor) \n" +
      "{ \n" +
      setColor;

    if (applyHighlight) {
      source += highlight;
    }

    source += "} \n";
    return source;
  }

  Cesium3DTileBatchTable.prototype.getFragmentShaderCallback = function (
    handleTranslucent,
    diffuseAttributeOrUniformName
  ) {
    if (this.featuresLength === 0) {
      return;
    }
    return function (source) {
      source = modifyDiffuse(source, diffuseAttributeOrUniformName, true);
      if (ContextLimits.maximumVertexTextureImageUnits > 0) {
        // When VTF is supported, per-feature show/hide already happened in the fragment shader
        source +=
          "uniform sampler2D tile_pickTexture; \n" +
          "varying vec2 tile_featureSt; \n" +
          "varying vec4 tile_featureColor; \n" +
          "void main() \n" +
          "{ \n" +
          "    tile_color(tile_featureColor); \n" +
          "}";
      } else {
        if (handleTranslucent) {
          source += "uniform bool tile_translucentCommand; \n";
        }
        source +=
          "uniform sampler2D tile_pickTexture; \n" +
          "uniform sampler2D tile_batchTexture; \n" +
          "varying vec2 tile_featureSt; \n" +
          "void main() \n" +
          "{ \n" +
          "    vec4 featureProperties = texture2D(tile_batchTexture, tile_featureSt); \n" +
          "    if (featureProperties.a == 0.0) { \n" + // show: alpha == 0 - false, non-zeo - true
          "        discard; \n" +
          "    } \n";

        if (handleTranslucent) {
          source +=
            "    bool isStyleTranslucent = (featureProperties.a != 1.0); \n" +
            "    if (czm_pass == czm_passTranslucent) \n" +
            "    { \n" +
            "        if (!isStyleTranslucent && !tile_translucentCommand) \n" + // Do not render opaque features in the translucent pass
            "        { \n" +
            "            discard; \n" +
            "        } \n" +
            "    } \n" +
            "    else \n" +
            "    { \n" +
            "        if (isStyleTranslucent) \n" + // Do not render translucent features in the opaque pass
            "        { \n" +
            "            discard; \n" +
            "        } \n" +
            "    } \n";
        }

        source += "    tile_color(featureProperties); \n" + "} \n";
      }
      return source;
    };
  };

  Cesium3DTileBatchTable.prototype.getClassificationFragmentShaderCallback = function () {
    if (this.featuresLength === 0) {
      return;
    }
    return function (source) {
      source = ShaderSource.replaceMain(source, "tile_main");
      if (ContextLimits.maximumVertexTextureImageUnits > 0) {
        // When VTF is supported, per-feature show/hide already happened in the fragment shader
        source +=
          "uniform sampler2D tile_pickTexture;\n" +
          "varying vec2 tile_featureSt; \n" +
          "varying vec4 tile_featureColor; \n" +
          "void main() \n" +
          "{ \n" +
          "    tile_main(); \n" +
          "    gl_FragColor = tile_featureColor; \n" +
          "}";
      } else {
        source +=
          "uniform sampler2D tile_batchTexture; \n" +
          "uniform sampler2D tile_pickTexture;\n" +
          "varying vec2 tile_featureSt; \n" +
          "void main() \n" +
          "{ \n" +
          "    tile_main(); \n" +
          "    vec4 featureProperties = texture2D(tile_batchTexture, tile_featureSt); \n" +
          "    if (featureProperties.a == 0.0) { \n" + // show: alpha == 0 - false, non-zeo - true
          "        discard; \n" +
          "    } \n" +
          "    gl_FragColor = featureProperties; \n" +
          "} \n";
      }
      return source;
    };
  };

  function getColorBlend(batchTable) {
    var tileset = batchTable._content.tileset;
    var colorBlendMode = tileset.colorBlendMode;
    var colorBlendAmount = tileset.colorBlendAmount;
    if (colorBlendMode === Cesium3DTileColorBlendMode$1.HIGHLIGHT) {
      return 0.0;
    }
    if (colorBlendMode === Cesium3DTileColorBlendMode$1.REPLACE) {
      return 1.0;
    }
    if (colorBlendMode === Cesium3DTileColorBlendMode$1.MIX) {
      // The value 0.0 is reserved for highlight, so clamp to just above 0.0.
      return CesiumMath.clamp(colorBlendAmount, CesiumMath.EPSILON4, 1.0);
    }
    //>>includeStart('debug', pragmas.debug);
    throw new DeveloperError(
      'Invalid color blend mode "' + colorBlendMode + '".'
    );
    //>>includeEnd('debug');
  }

  Cesium3DTileBatchTable.prototype.getUniformMapCallback = function () {
    if (this.featuresLength === 0) {
      return;
    }

    var that = this;
    return function (uniformMap) {
      var batchUniformMap = {
        tile_batchTexture: function () {
          // PERFORMANCE_IDEA: we could also use a custom shader that avoids the texture read.
          return defaultValue(that._batchTexture, that._defaultTexture);
        },
        tile_textureDimensions: function () {
          return that._textureDimensions;
        },
        tile_textureStep: function () {
          return that._textureStep;
        },
        tile_colorBlend: function () {
          return getColorBlend(that);
        },
        tile_pickTexture: function () {
          return that._pickTexture;
        },
      };

      return combine(uniformMap, batchUniformMap);
    };
  };

  Cesium3DTileBatchTable.prototype.getPickId = function () {
    return "texture2D(tile_pickTexture, tile_featureSt)";
  };

  ///////////////////////////////////////////////////////////////////////////

  var StyleCommandsNeeded = {
    ALL_OPAQUE: 0,
    ALL_TRANSLUCENT: 1,
    OPAQUE_AND_TRANSLUCENT: 2,
  };

  Cesium3DTileBatchTable.prototype.addDerivedCommands = function (
    frameState,
    commandStart
  ) {
    var commandList = frameState.commandList;
    var commandEnd = commandList.length;
    var tile = this._content._tile;
    var finalResolution = tile._finalResolution;
    var tileset = tile.tileset;
    var bivariateVisibilityTest =
      tileset._skipLevelOfDetail &&
      tileset._hasMixedContent &&
      frameState.context.stencilBuffer;
    var styleCommandsNeeded = getStyleCommandsNeeded(this);

    for (var i = commandStart; i < commandEnd; ++i) {
      var command = commandList[i];
      var derivedCommands = command.derivedCommands.tileset;
      if (!defined(derivedCommands) || command.dirty) {
        derivedCommands = {};
        command.derivedCommands.tileset = derivedCommands;
        derivedCommands.originalCommand = deriveCommand(command);
        command.dirty = false;
      }
      var originalCommand = derivedCommands.originalCommand;

      if (
        styleCommandsNeeded !== StyleCommandsNeeded.ALL_OPAQUE &&
        command.pass !== Pass$1.TRANSLUCENT
      ) {
        if (!defined(derivedCommands.translucent)) {
          derivedCommands.translucent = deriveTranslucentCommand(originalCommand);
        }
      }

      if (
        styleCommandsNeeded !== StyleCommandsNeeded.ALL_TRANSLUCENT &&
        command.pass !== Pass$1.TRANSLUCENT
      ) {
        if (!defined(derivedCommands.opaque)) {
          derivedCommands.opaque = deriveOpaqueCommand(originalCommand);
        }

        if (bivariateVisibilityTest) {
          if (!finalResolution) {
            if (!defined(derivedCommands.zback)) {
              derivedCommands.zback = deriveZBackfaceCommand(
                frameState.context,
                originalCommand
              );
            }
            tileset._backfaceCommands.push(derivedCommands.zback);
          }
          if (
            !defined(derivedCommands.stencil) ||
            tile._selectionDepth !==
              getLastSelectionDepth(derivedCommands.stencil)
          ) {
            if (command.renderState.depthMask) {
              derivedCommands.stencil = deriveStencilCommand(
                originalCommand,
                tile._selectionDepth
              );
            } else {
              // Ignore if tile does not write depth
              derivedCommands.stencil = derivedCommands.opaque;
            }
          }
        }
      }

      var opaqueCommand = bivariateVisibilityTest
        ? derivedCommands.stencil
        : derivedCommands.opaque;
      var translucentCommand = derivedCommands.translucent;

      // If the command was originally opaque:
      //    * If the styling applied to the tile is all opaque, use the opaque command
      //      (with one additional uniform needed for the shader).
      //    * If the styling is all translucent, use new (cached) derived commands (front
      //      and back faces) with a translucent render state.
      //    * If the styling causes both opaque and translucent features in this tile,
      //      then use both sets of commands.
      if (command.pass !== Pass$1.TRANSLUCENT) {
        if (styleCommandsNeeded === StyleCommandsNeeded.ALL_OPAQUE) {
          commandList[i] = opaqueCommand;
        }
        if (styleCommandsNeeded === StyleCommandsNeeded.ALL_TRANSLUCENT) {
          commandList[i] = translucentCommand;
        }
        if (styleCommandsNeeded === StyleCommandsNeeded.OPAQUE_AND_TRANSLUCENT) {
          // PERFORMANCE_IDEA: if the tile has multiple commands, we do not know what features are in what
          // commands so this case may be overkill.
          commandList[i] = opaqueCommand;
          commandList.push(translucentCommand);
        }
      } else {
        // Command was originally translucent so no need to derive new commands;
        // as of now, a style can't change an originally translucent feature to
        // opaque since the style's alpha is modulated, not a replacement.  When
        // this changes, we need to derive new opaque commands here.
        commandList[i] = originalCommand;
      }
    }
  };

  function getStyleCommandsNeeded(batchTable) {
    var translucentFeaturesLength = batchTable._translucentFeaturesLength;

    if (translucentFeaturesLength === 0) {
      return StyleCommandsNeeded.ALL_OPAQUE;
    } else if (translucentFeaturesLength === batchTable.featuresLength) {
      return StyleCommandsNeeded.ALL_TRANSLUCENT;
    }

    return StyleCommandsNeeded.OPAQUE_AND_TRANSLUCENT;
  }

  function deriveCommand(command) {
    var derivedCommand = DrawCommand.shallowClone(command);

    // Add a uniform to indicate if the original command was translucent so
    // the shader knows not to cull vertices that were originally transparent
    // even though their style is opaque.
    var translucentCommand = derivedCommand.pass === Pass$1.TRANSLUCENT;

    derivedCommand.uniformMap = defined(derivedCommand.uniformMap)
      ? derivedCommand.uniformMap
      : {};
    derivedCommand.uniformMap.tile_translucentCommand = function () {
      return translucentCommand;
    };

    return derivedCommand;
  }

  function deriveTranslucentCommand(command) {
    var derivedCommand = DrawCommand.shallowClone(command);
    derivedCommand.pass = Pass$1.TRANSLUCENT;
    derivedCommand.renderState = getTranslucentRenderState(command.renderState);
    return derivedCommand;
  }

  function deriveOpaqueCommand(command) {
    var derivedCommand = DrawCommand.shallowClone(command);
    derivedCommand.renderState = getOpaqueRenderState(command.renderState);
    return derivedCommand;
  }

  function getLogDepthPolygonOffsetFragmentShaderProgram(context, shaderProgram) {
    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      "zBackfaceLogDepth"
    );
    if (!defined(shader)) {
      var fs = shaderProgram.fragmentShaderSource.clone();
      fs.defines = defined(fs.defines) ? fs.defines.slice(0) : [];
      fs.defines.push("POLYGON_OFFSET");

      fs.sources.unshift(
        "#ifdef GL_OES_standard_derivatives\n#extension GL_OES_standard_derivatives : enable\n#endif\n"
      );
      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        "zBackfaceLogDepth",
        {
          vertexShaderSource: shaderProgram.vertexShaderSource,
          fragmentShaderSource: fs,
          attributeLocations: shaderProgram._attributeLocations,
        }
      );
    }

    return shader;
  }

  function deriveZBackfaceCommand(context, command) {
    // Write just backface depth of unresolved tiles so resolved stenciled tiles do not appear in front
    var derivedCommand = DrawCommand.shallowClone(command);
    var rs = clone(derivedCommand.renderState, true);
    rs.cull.enabled = true;
    rs.cull.face = CullFace$1.FRONT;
    // Back faces do not need to write color.
    rs.colorMask = {
      red: false,
      green: false,
      blue: false,
      alpha: false,
    };
    // Push back face depth away from the camera so it is less likely that back faces and front faces of the same tile
    // intersect and overlap. This helps avoid flickering for very thin double-sided walls.
    rs.polygonOffset = {
      enabled: true,
      factor: 5.0,
      units: 5.0,
    };
    // Set the 3D Tiles bit
    rs.stencilTest = StencilConstants$1.setCesium3DTileBit();
    rs.stencilMask = StencilConstants$1.CESIUM_3D_TILE_MASK;

    derivedCommand.renderState = RenderState.fromCache(rs);
    derivedCommand.castShadows = false;
    derivedCommand.receiveShadows = false;
    derivedCommand.uniformMap = clone(command.uniformMap);

    var polygonOffset = new Cartesian2(5.0, 5.0);
    derivedCommand.uniformMap.u_polygonOffset = function () {
      return polygonOffset;
    };

    // Make the log depth depth fragment write account for the polygon offset, too.
    // Otherwise, the back face commands will cause the higher resolution
    // tiles to disappear.
    derivedCommand.shaderProgram = getLogDepthPolygonOffsetFragmentShaderProgram(
      context,
      command.shaderProgram
    );
    return derivedCommand;
  }

  function deriveStencilCommand(command, reference) {
    // Tiles only draw if their selection depth is >= the tile drawn already. They write their
    // selection depth to the stencil buffer to prevent ancestor tiles from drawing on top
    var derivedCommand = DrawCommand.shallowClone(command);
    var rs = clone(derivedCommand.renderState, true);
    // Stencil test is masked to the most significant 3 bits so the reference is shifted. Writes 0 for the terrain bit
    rs.stencilTest.enabled = true;
    rs.stencilTest.mask = StencilConstants$1.SKIP_LOD_MASK;
    rs.stencilTest.reference =
      StencilConstants$1.CESIUM_3D_TILE_MASK |
      (reference << StencilConstants$1.SKIP_LOD_BIT_SHIFT);
    rs.stencilTest.frontFunction = StencilFunction$1.GREATER_OR_EQUAL;
    rs.stencilTest.frontOperation.zPass = StencilOperation$1.REPLACE;
    rs.stencilTest.backFunction = StencilFunction$1.GREATER_OR_EQUAL;
    rs.stencilTest.backOperation.zPass = StencilOperation$1.REPLACE;
    rs.stencilMask =
      StencilConstants$1.CESIUM_3D_TILE_MASK | StencilConstants$1.SKIP_LOD_MASK;
    derivedCommand.renderState = RenderState.fromCache(rs);
    return derivedCommand;
  }

  function getLastSelectionDepth(stencilCommand) {
    // Isolate the selection depth from the stencil reference.
    var reference = stencilCommand.renderState.stencilTest.reference;
    return (
      (reference & StencilConstants$1.SKIP_LOD_MASK) >>>
      StencilConstants$1.SKIP_LOD_BIT_SHIFT
    );
  }

  function getTranslucentRenderState(renderState) {
    var rs = clone(renderState, true);
    rs.cull.enabled = false;
    rs.depthTest.enabled = true;
    rs.depthMask = false;
    rs.blending = BlendingState$1.ALPHA_BLEND;

    return RenderState.fromCache(rs);
  }

  function getOpaqueRenderState(renderState) {
    var rs = clone(renderState, true);
    rs.stencilTest = StencilConstants$1.setCesium3DTileBit();
    rs.stencilMask = StencilConstants$1.CESIUM_3D_TILE_MASK;

    return RenderState.fromCache(rs);
  }

  ///////////////////////////////////////////////////////////////////////////

  function createTexture$1(batchTable, context, bytes) {
    var dimensions = batchTable._textureDimensions;
    return new Texture({
      context: context,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      source: {
        width: dimensions.x,
        height: dimensions.y,
        arrayBufferView: bytes,
      },
      flipY: false,
      sampler: Sampler.NEAREST,
    });
  }

  function createPickTexture(batchTable, context) {
    var featuresLength = batchTable.featuresLength;
    if (!defined(batchTable._pickTexture) && featuresLength > 0) {
      var pickIds = batchTable._pickIds;
      var byteLength = getByteLength(batchTable);
      var bytes = new Uint8Array(byteLength);
      var content = batchTable._content;

      // PERFORMANCE_IDEA: we could skip the pick texture completely by allocating
      // a continuous range of pickIds and then converting the base pickId + batchId
      // to RGBA in the shader.  The only consider is precision issues, which might
      // not be an issue in WebGL 2.
      for (var i = 0; i < featuresLength; ++i) {
        var pickId = context.createPickId(content.getFeature(i));
        pickIds.push(pickId);

        var pickColor = pickId.color;
        var offset = i * 4;
        bytes[offset] = Color.floatToByte(pickColor.red);
        bytes[offset + 1] = Color.floatToByte(pickColor.green);
        bytes[offset + 2] = Color.floatToByte(pickColor.blue);
        bytes[offset + 3] = Color.floatToByte(pickColor.alpha);
      }

      batchTable._pickTexture = createTexture$1(batchTable, context, bytes);
      content.tileset._statistics.batchTableByteLength +=
        batchTable._pickTexture.sizeInBytes;
    }
  }

  function updateBatchTexture(batchTable) {
    var dimensions = batchTable._textureDimensions;
    // PERFORMANCE_IDEA: Instead of rewriting the entire texture, use fine-grained
    // texture updates when less than, for example, 10%, of the values changed.  Or
    // even just optimize the common case when one feature show/color changed.
    batchTable._batchTexture.copyFrom({
      width: dimensions.x,
      height: dimensions.y,
      arrayBufferView: batchTable._batchValues,
    });
  }

  Cesium3DTileBatchTable.prototype.update = function (tileset, frameState) {
    var context = frameState.context;
    this._defaultTexture = context.defaultTexture;

    var passes = frameState.passes;
    if (passes.pick || passes.postProcess) {
      createPickTexture(this, context);
    }

    if (this._batchValuesDirty) {
      this._batchValuesDirty = false;

      // Create batch texture on-demand
      if (!defined(this._batchTexture)) {
        this._batchTexture = createTexture$1(this, context, this._batchValues);
        tileset._statistics.batchTableByteLength += this._batchTexture.sizeInBytes;
      }

      updateBatchTexture(this); // Apply per-feature show/color updates
    }
  };

  Cesium3DTileBatchTable.prototype.isDestroyed = function () {
    return false;
  };

  Cesium3DTileBatchTable.prototype.destroy = function () {
    this._batchTexture = this._batchTexture && this._batchTexture.destroy();
    this._pickTexture = this._pickTexture && this._pickTexture.destroy();

    var pickIds = this._pickIds;
    var length = pickIds.length;
    for (var i = 0; i < length; ++i) {
      pickIds[i].destroy();
    }

    return destroyObject(this);
  };

  /**
   * A feature of a {@link Cesium3DTileset}.
   * <p>
   * Provides access to a feature's properties stored in the tile's batch table, as well
   * as the ability to show/hide a feature and change its highlight color via
   * {@link Cesium3DTileFeature#show} and {@link Cesium3DTileFeature#color}, respectively.
   * </p>
   * <p>
   * Modifications to a <code>Cesium3DTileFeature</code> object have the lifetime of the tile's
   * content.  If the tile's content is unloaded, e.g., due to it going out of view and needing
   * to free space in the cache for visible tiles, listen to the {@link Cesium3DTileset#tileUnload} event to save any
   * modifications. Also listen to the {@link Cesium3DTileset#tileVisible} event to reapply any modifications.
   * </p>
   * <p>
   * Do not construct this directly.  Access it through {@link Cesium3DTileContent#getFeature}
   * or picking using {@link Scene#pick} and {@link Scene#pickPosition}.
   * </p>
   *
   * @alias Cesium3DTileFeature
   * @constructor
   *
   * @example
   * // On mouse over, display all the properties for a feature in the console log.
   * handler.setInputAction(function(movement) {
   *     var feature = scene.pick(movement.endPosition);
   *     if (feature instanceof Cesium.Cesium3DTileFeature) {
   *         var propertyNames = feature.getPropertyNames();
   *         var length = propertyNames.length;
   *         for (var i = 0; i < length; ++i) {
   *             var propertyName = propertyNames[i];
   *             console.log(propertyName + ': ' + feature.getProperty(propertyName));
   *         }
   *     }
   * }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
   */
  function Cesium3DTileFeature(content, batchId) {
    this._content = content;
    this._batchId = batchId;
    this._color = undefined; // for calling getColor
  }

  Object.defineProperties(Cesium3DTileFeature.prototype, {
    /**
     * Gets or sets if the feature will be shown. This is set for all features
     * when a style's show is evaluated.
     *
     * @memberof Cesium3DTileFeature.prototype
     *
     * @type {Boolean}
     *
     * @default true
     */
    show: {
      get: function () {
        return this._content.batchTable.getShow(this._batchId);
      },
      set: function (value) {
        this._content.batchTable.setShow(this._batchId, value);
      },
    },

    /**
     * Gets or sets the highlight color multiplied with the feature's color.  When
     * this is white, the feature's color is not changed. This is set for all features
     * when a style's color is evaluated.
     *
     * @memberof Cesium3DTileFeature.prototype
     *
     * @type {Color}
     *
     * @default {@link Color.WHITE}
     */
    color: {
      get: function () {
        if (!defined(this._color)) {
          this._color = new Color();
        }
        return this._content.batchTable.getColor(this._batchId, this._color);
      },
      set: function (value) {
        this._content.batchTable.setColor(this._batchId, value);
      },
    },

    /**
     * Gets the content of the tile containing the feature.
     *
     * @memberof Cesium3DTileFeature.prototype
     *
     * @type {Cesium3DTileContent}
     *
     * @readonly
     * @private
     */
    content: {
      get: function () {
        return this._content;
      },
    },

    /**
     * Gets the tileset containing the feature.
     *
     * @memberof Cesium3DTileFeature.prototype
     *
     * @type {Cesium3DTileset}
     *
     * @readonly
     */
    tileset: {
      get: function () {
        return this._content.tileset;
      },
    },

    /**
     * All objects returned by {@link Scene#pick} have a <code>primitive</code> property. This returns
     * the tileset containing the feature.
     *
     * @memberof Cesium3DTileFeature.prototype
     *
     * @type {Cesium3DTileset}
     *
     * @readonly
     */
    primitive: {
      get: function () {
        return this._content.tileset;
      },
    },

    /**
     * @private
     */
    pickId: {
      get: function () {
        return this._content.batchTable.getPickColor(this._batchId);
      },
    },
  });

  /**
   * Returns whether the feature contains this property. This includes properties from this feature's
   * class and inherited classes when using a batch table hierarchy.
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/extensions/3DTILES_batch_table_hierarchy}
   *
   * @param {String} name The case-sensitive name of the property.
   * @returns {Boolean} Whether the feature contains this property.
   */
  Cesium3DTileFeature.prototype.hasProperty = function (name) {
    return this._content.batchTable.hasProperty(this._batchId, name);
  };

  /**
   * Returns an array of property names for the feature. This includes properties from this feature's
   * class and inherited classes when using a batch table hierarchy.
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/extensions/3DTILES_batch_table_hierarchy}
   *
   * @param {String[]} [results] An array into which to store the results.
   * @returns {String[]} The names of the feature's properties.
   */
  Cesium3DTileFeature.prototype.getPropertyNames = function (results) {
    return this._content.batchTable.getPropertyNames(this._batchId, results);
  };

  /**
   * Returns a copy of the value of the feature's property with the given name. This includes properties from this feature's
   * class and inherited classes when using a batch table hierarchy.
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/extensions/3DTILES_batch_table_hierarchy}
   *
   * @param {String} name The case-sensitive name of the property.
   * @returns {*} The value of the property or <code>undefined</code> if the property does not exist.
   *
   * @example
   * // Display all the properties for a feature in the console log.
   * var propertyNames = feature.getPropertyNames();
   * var length = propertyNames.length;
   * for (var i = 0; i < length; ++i) {
   *     var propertyName = propertyNames[i];
   *     console.log(propertyName + ': ' + feature.getProperty(propertyName));
   * }
   */
  Cesium3DTileFeature.prototype.getProperty = function (name) {
    return this._content.batchTable.getProperty(this._batchId, name);
  };

  /**
   * Sets the value of the feature's property with the given name.
   * <p>
   * If a property with the given name doesn't exist, it is created.
   * </p>
   *
   * @param {String} name The case-sensitive name of the property.
   * @param {*} value The value of the property that will be copied.
   *
   * @exception {DeveloperError} Inherited batch table hierarchy property is read only.
   *
   * @example
   * var height = feature.getProperty('Height'); // e.g., the height of a building
   *
   * @example
   * var name = 'clicked';
   * if (feature.getProperty(name)) {
   *     console.log('already clicked');
   * } else {
   *     feature.setProperty(name, true);
   *     console.log('first click');
   * }
   */
  Cesium3DTileFeature.prototype.setProperty = function (name, value) {
    this._content.batchTable.setProperty(this._batchId, name, value);

    // PERFORMANCE_IDEA: Probably overkill, but maybe only mark the tile dirty if the
    // property is in one of the style's expressions or - if it can be done quickly -
    // if the new property value changed the result of an expression.
    this._content.featurePropertiesDirty = true;
  };

  /**
   * Returns whether the feature's class name equals <code>className</code>. Unlike {@link Cesium3DTileFeature#isClass}
   * this function only checks the feature's exact class and not inherited classes.
   * <p>
   * This function returns <code>false</code> if no batch table hierarchy is present.
   * </p>
   *
   * @param {String} className The name to check against.
   * @returns {Boolean} Whether the feature's class name equals <code>className</code>
   *
   * @private
   */
  Cesium3DTileFeature.prototype.isExactClass = function (className) {
    return this._content.batchTable.isExactClass(this._batchId, className);
  };

  /**
   * Returns whether the feature's class or any inherited classes are named <code>className</code>.
   * <p>
   * This function returns <code>false</code> if no batch table hierarchy is present.
   * </p>
   *
   * @param {String} className The name to check against.
   * @returns {Boolean} Whether the feature's class or inherited classes are named <code>className</code>
   *
   * @private
   */
  Cesium3DTileFeature.prototype.isClass = function (className) {
    return this._content.batchTable.isClass(this._batchId, className);
  };

  /**
   * Returns the feature's class name.
   * <p>
   * This function returns <code>undefined</code> if no batch table hierarchy is present.
   * </p>
   *
   * @returns {String} The feature's class name.
   *
   * @private
   */
  Cesium3DTileFeature.prototype.getExactClassName = function () {
    return this._content.batchTable.getExactClassName(this._batchId);
  };

  /**
   * @private
   */
  function Cesium3DTileFeatureTable(featureTableJson, featureTableBinary) {
    this.json = featureTableJson;
    this.buffer = featureTableBinary;
    this._cachedTypedArrays = {};
    this.featuresLength = 0;
  }

  function getTypedArrayFromBinary(
    featureTable,
    semantic,
    componentType,
    componentLength,
    count,
    byteOffset
  ) {
    var cachedTypedArrays = featureTable._cachedTypedArrays;
    var typedArray = cachedTypedArrays[semantic];
    if (!defined(typedArray)) {
      typedArray = ComponentDatatype$1.createArrayBufferView(
        componentType,
        featureTable.buffer.buffer,
        featureTable.buffer.byteOffset + byteOffset,
        count * componentLength
      );
      cachedTypedArrays[semantic] = typedArray;
    }
    return typedArray;
  }

  function getTypedArrayFromArray(featureTable, semantic, componentType, array) {
    var cachedTypedArrays = featureTable._cachedTypedArrays;
    var typedArray = cachedTypedArrays[semantic];
    if (!defined(typedArray)) {
      typedArray = ComponentDatatype$1.createTypedArray(componentType, array);
      cachedTypedArrays[semantic] = typedArray;
    }
    return typedArray;
  }

  Cesium3DTileFeatureTable.prototype.getGlobalProperty = function (
    semantic,
    componentType,
    componentLength
  ) {
    var jsonValue = this.json[semantic];
    if (!defined(jsonValue)) {
      return undefined;
    }

    if (defined(jsonValue.byteOffset)) {
      componentType = defaultValue(componentType, ComponentDatatype$1.UNSIGNED_INT);
      componentLength = defaultValue(componentLength, 1);
      return getTypedArrayFromBinary(
        this,
        semantic,
        componentType,
        componentLength,
        1,
        jsonValue.byteOffset
      );
    }

    return jsonValue;
  };

  Cesium3DTileFeatureTable.prototype.getPropertyArray = function (
    semantic,
    componentType,
    componentLength
  ) {
    var jsonValue = this.json[semantic];
    if (!defined(jsonValue)) {
      return undefined;
    }

    if (defined(jsonValue.byteOffset)) {
      if (defined(jsonValue.componentType)) {
        componentType = ComponentDatatype$1.fromName(jsonValue.componentType);
      }
      return getTypedArrayFromBinary(
        this,
        semantic,
        componentType,
        componentLength,
        this.featuresLength,
        jsonValue.byteOffset
      );
    }

    return getTypedArrayFromArray(this, semantic, componentType, jsonValue);
  };

  Cesium3DTileFeatureTable.prototype.getProperty = function (
    semantic,
    componentType,
    componentLength,
    featureId,
    result
  ) {
    var jsonValue = this.json[semantic];
    if (!defined(jsonValue)) {
      return undefined;
    }

    var typedArray = this.getPropertyArray(
      semantic,
      componentType,
      componentLength
    );

    if (componentLength === 1) {
      return typedArray[featureId];
    }

    for (var i = 0; i < componentLength; ++i) {
      result[i] = typedArray[componentLength * featureId + i];
    }

    return result;
  };

  /**
       * Adds an element to an array and returns the element's index.
       *
       * @param {Array} array The array to add to.
       * @param {Object} element The element to add.
       * @param {Boolean} [checkDuplicates=false] When <code>true</code>, if a duplicate element is found its index is returned and <code>element</code> is not added to the array.
       *
       * @private
       */
      function addToArray(array, element, checkDuplicates) {
          checkDuplicates = defaultValue(checkDuplicates, false);
          if (checkDuplicates) {
              var index = array.indexOf(element);
              if (index > -1) {
                  return index;
              }
          }

          array.push(element);
          return array.length - 1;
      }

  /**
       * Checks whether the glTF has the given extension.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {String} extension The name of the extension.
       * @returns {Boolean} Whether the glTF has the given extension.
       *
       * @private
       */
      function hasExtension(gltf, extension) {
          return defined(gltf.extensionsUsed) && (gltf.extensionsUsed.indexOf(extension) >= 0);
      }

  /**
       * Contains traversal functions for processing elements of the glTF hierarchy.
       * @constructor
       *
       * @private
       */
      function ForEach() {
      }

      /**
       * Fallback for glTF 1.0
       * @private
       */
      ForEach.objectLegacy = function(objects, handler) {
          if (defined(objects)) {
              for (var objectId in objects) {
                  if (Object.prototype.hasOwnProperty.call(objects, objectId)) {
                      var object = objects[objectId];
                      var value = handler(object, objectId);

                      if (defined(value)) {
                          return value;
                      }
                  }
              }
          }
      };

      /**
       * @private
       */
      ForEach.object = function(arrayOfObjects, handler) {
          if (defined(arrayOfObjects)) {
              var length = arrayOfObjects.length;
              for (var i = 0; i < length; i++) {
                  var object = arrayOfObjects[i];
                  var value = handler(object, i);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      /**
       * Supports glTF 1.0 and 2.0
       * @private
       */
      ForEach.topLevel = function(gltf, name, handler) {
          var gltfProperty = gltf[name];
          if (defined(gltfProperty) && !Array.isArray(gltfProperty)) {
              return ForEach.objectLegacy(gltfProperty, handler);
          }

          return ForEach.object(gltfProperty, handler);
      };

      ForEach.accessor = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'accessors', handler);
      };

      ForEach.accessorWithSemantic = function(gltf, semantic, handler) {
          var visited = {};
          return ForEach.mesh(gltf, function(mesh) {
              return ForEach.meshPrimitive(mesh, function(primitive) {
                  var valueForEach = ForEach.meshPrimitiveAttribute(primitive, function(accessorId, attributeSemantic) {
                      if (attributeSemantic.indexOf(semantic) === 0 && !defined(visited[accessorId])) {
                          visited[accessorId] = true;
                          var value = handler(accessorId);

                          if (defined(value)) {
                              return value;
                          }
                      }
                  });

                  if (defined(valueForEach)) {
                      return valueForEach;
                  }

                  return ForEach.meshPrimitiveTarget(primitive, function(target) {
                      return ForEach.meshPrimitiveTargetAttribute(target, function(accessorId, attributeSemantic) {
                          if (attributeSemantic.indexOf(semantic) === 0 && !defined(visited[accessorId])) {
                              visited[accessorId] = true;
                              var value = handler(accessorId);

                              if (defined(value)) {
                                  return value;
                              }
                          }
                      });
                  });
              });
          });
      };

      ForEach.accessorContainingVertexAttributeData = function(gltf, handler) {
          var visited = {};
          return ForEach.mesh(gltf, function(mesh) {
              return ForEach.meshPrimitive(mesh, function(primitive) {
                  var valueForEach = ForEach.meshPrimitiveAttribute(primitive, function(accessorId) {
                      if (!defined(visited[accessorId])) {
                          visited[accessorId] = true;
                          var value = handler(accessorId);

                          if (defined(value)) {
                              return value;
                          }
                      }
                  });

                  if (defined(valueForEach)) {
                      return valueForEach;
                  }

                  return ForEach.meshPrimitiveTarget(primitive, function(target) {
                      return ForEach.meshPrimitiveTargetAttribute(target, function(accessorId) {
                          if (!defined(visited[accessorId])) {
                              visited[accessorId] = true;
                              var value = handler(accessorId);

                              if (defined(value)) {
                                  return value;
                              }
                          }
                      });
                  });
              });
          });
      };

      ForEach.accessorContainingIndexData = function(gltf, handler) {
          var visited = {};
          return ForEach.mesh(gltf, function(mesh) {
              return ForEach.meshPrimitive(mesh, function(primitive) {
                  var indices = primitive.indices;
                  if (defined(indices) && !defined(visited[indices])) {
                      visited[indices] = true;
                      var value = handler(indices);

                      if (defined(value)) {
                          return value;
                      }
                  }
              });
          });
      };

      ForEach.animation = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'animations', handler);
      };

      ForEach.animationChannel = function(animation, handler) {
          var channels = animation.channels;
          return ForEach.object(channels, handler);
      };

      ForEach.animationSampler = function(animation, handler) {
          var samplers = animation.samplers;
          return ForEach.object(samplers, handler);
      };

      ForEach.buffer = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'buffers', handler);
      };

      ForEach.bufferView = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'bufferViews', handler);
      };

      ForEach.camera = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'cameras', handler);
      };

      ForEach.image = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'images', handler);
      };

      ForEach.compressedImage = function(image, handler) {
          if (defined(image.extras)) {
              var compressedImages = image.extras.compressedImage3DTiles;
              for (var type in compressedImages) {
                  if (Object.prototype.hasOwnProperty.call(compressedImages, type)) {
                      var compressedImage = compressedImages[type];
                      var value = handler(compressedImage, type);

                      if (defined(value)) {
                          return value;
                      }
                  }
              }
          }
      };

      ForEach.material = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'materials', handler);
      };

      ForEach.materialValue = function(material, handler) {
          var values = material.values;
          if (defined(material.extensions) && defined(material.extensions.KHR_techniques_webgl)) {
              values = material.extensions.KHR_techniques_webgl.values;
          }

          for (var name in values) {
              if (Object.prototype.hasOwnProperty.call(values, name)) {
                  var value = handler(values[name], name);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.mesh = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'meshes', handler);
      };

      ForEach.meshPrimitive = function(mesh, handler) {
          var primitives = mesh.primitives;
          if (defined(primitives)) {
              var primitivesLength = primitives.length;
              for (var i = 0; i < primitivesLength; i++) {
                  var primitive = primitives[i];
                  var value = handler(primitive, i);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.meshPrimitiveAttribute = function(primitive, handler) {
          var attributes = primitive.attributes;
          for (var semantic in attributes) {
              if (Object.prototype.hasOwnProperty.call(attributes, semantic)) {
                  var value = handler(attributes[semantic], semantic);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.meshPrimitiveTarget = function(primitive, handler) {
          var targets = primitive.targets;
          if (defined(targets)) {
              var length = targets.length;
              for (var i = 0; i < length; ++i) {
                  var value = handler(targets[i], i);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.meshPrimitiveTargetAttribute = function(target, handler) {
          for (var semantic in target) {
              if (Object.prototype.hasOwnProperty.call(target, semantic)) {
                  var accessorId = target[semantic];
                  var value = handler(accessorId, semantic);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.node = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'nodes', handler);
      };

      ForEach.nodeInTree = function(gltf, nodeIds, handler) {
          var nodes = gltf.nodes;
          if (defined(nodes)) {
              var length = nodeIds.length;
              for (var i = 0; i < length; i++) {
                  var nodeId = nodeIds[i];
                  var node = nodes[nodeId];
                  if (defined(node)) {
                      var value = handler(node, nodeId);

                      if (defined(value)) {
                          return value;
                      }

                      var children = node.children;
                      if (defined(children)) {
                          value = ForEach.nodeInTree(gltf, children, handler);

                          if (defined(value)) {
                              return value;
                          }
                      }
                  }
              }
          }
      };

      ForEach.nodeInScene = function(gltf, scene, handler) {
          var sceneNodeIds = scene.nodes;
          if (defined(sceneNodeIds)) {
              return ForEach.nodeInTree(gltf, sceneNodeIds, handler);
          }
      };

      ForEach.program = function(gltf, handler) {
          if (hasExtension(gltf, 'KHR_techniques_webgl')) {
              return ForEach.object(gltf.extensions.KHR_techniques_webgl.programs, handler);
          }

          return ForEach.topLevel(gltf, 'programs', handler);
      };

      ForEach.sampler = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'samplers', handler);
      };

      ForEach.scene = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'scenes', handler);
      };

      ForEach.shader = function(gltf, handler) {
          if (hasExtension(gltf, 'KHR_techniques_webgl')) {
              return ForEach.object(gltf.extensions.KHR_techniques_webgl.shaders, handler);
          }

          return ForEach.topLevel(gltf, 'shaders', handler);
      };

      ForEach.skin = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'skins', handler);
      };

      ForEach.skinJoint = function(skin, handler) {
          var joints = skin.joints;
          if (defined(joints)) {
              var jointsLength = joints.length;
              for (var i = 0; i < jointsLength; i++) {
                  var joint = joints[i];
                  var value = handler(joint);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.techniqueAttribute = function(technique, handler) {
          var attributes = technique.attributes;
          for (var attributeName in attributes) {
              if (Object.prototype.hasOwnProperty.call(attributes, attributeName)) {
                  var value = handler(attributes[attributeName], attributeName);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.techniqueUniform = function(technique, handler) {
          var uniforms = technique.uniforms;
          for (var uniformName in uniforms) {
              if (Object.prototype.hasOwnProperty.call(uniforms, uniformName)) {
                  var value = handler(uniforms[uniformName], uniformName);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.techniqueParameter = function(technique, handler) {
          var parameters = technique.parameters;
          for (var parameterName in parameters) {
              if (Object.prototype.hasOwnProperty.call(parameters, parameterName)) {
                  var value = handler(parameters[parameterName], parameterName);

                  if (defined(value)) {
                      return value;
                  }
              }
          }
      };

      ForEach.technique = function(gltf, handler) {
          if (hasExtension(gltf, 'KHR_techniques_webgl')) {
              return ForEach.object(gltf.extensions.KHR_techniques_webgl.techniques, handler);
          }

          return ForEach.topLevel(gltf, 'techniques', handler);
      };

      ForEach.texture = function(gltf, handler) {
          return ForEach.topLevel(gltf, 'textures', handler);
      };

  /**
       * Utility function for retrieving the number of components in a given type.
       *
       * @param {String} type glTF type
       * @returns {Number} The number of components in that type.
       *
       * @private
       */
      function numberOfComponentsForType(type) {
          switch (type) {
              case 'SCALAR':
                  return 1;
              case 'VEC2':
                  return 2;
              case 'VEC3':
                  return 3;
              case 'VEC4':
              case 'MAT2':
                  return 4;
              case 'MAT3':
                  return 9;
              case 'MAT4':
                  return 16;
          }
      }

  /**
       * Returns the byte stride of the provided accessor.
       * If the byteStride is 0, it is calculated based on type and componentType
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {Object} accessor The accessor.
       * @returns {Number} The byte stride of the accessor.
       *
       * @private
       */
      function getAccessorByteStride(gltf, accessor) {
          var bufferViewId = accessor.bufferView;
          if (defined(bufferViewId)) {
              var bufferView = gltf.bufferViews[bufferViewId];
              if (defined(bufferView.byteStride) && bufferView.byteStride > 0) {
                  return bufferView.byteStride;
              }
          }
          return ComponentDatatype$1.getSizeInBytes(accessor.componentType) * numberOfComponentsForType(accessor.type);
      }

  /**
       * Adds default glTF values if they don't exist.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @returns {Object} The modified glTF.
       *
       * @private
       */
      function addDefaults(gltf) {
          ForEach.accessor(gltf, function(accessor) {
              if (defined(accessor.bufferView)) {
                  accessor.byteOffset = defaultValue(accessor.byteOffset, 0);
              }
          });

          ForEach.bufferView(gltf, function(bufferView) {
              if (defined(bufferView.buffer)) {
                  bufferView.byteOffset = defaultValue(bufferView.byteOffset, 0);
              }
          });

          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  primitive.mode = defaultValue(primitive.mode, WebGLConstants$1.TRIANGLES);
                  if (!defined(primitive.material)) {
                      if (!defined(gltf.materials)) {
                          gltf.materials = [];
                      }
                      var defaultMaterial = {
                          name: 'default'
                      };
                      primitive.material = addToArray(gltf.materials, defaultMaterial);
                  }
              });
          });

          ForEach.accessorContainingVertexAttributeData(gltf, function(accessorId) {
              var accessor = gltf.accessors[accessorId];
              var bufferViewId = accessor.bufferView;
              accessor.normalized = defaultValue(accessor.normalized, false);
              if (defined(bufferViewId)) {
                  var bufferView = gltf.bufferViews[bufferViewId];
                  bufferView.byteStride = getAccessorByteStride(gltf, accessor);
                  bufferView.target = WebGLConstants$1.ARRAY_BUFFER;
              }
          });

          ForEach.accessorContainingIndexData(gltf, function(accessorId) {
              var accessor = gltf.accessors[accessorId];
              var bufferViewId = accessor.bufferView;
              if (defined(bufferViewId)) {
                  var bufferView = gltf.bufferViews[bufferViewId];
                  bufferView.target = WebGLConstants$1.ELEMENT_ARRAY_BUFFER;
              }
          });

          ForEach.material(gltf, function(material) {
              var extensions = defaultValue(material.extensions, defaultValue.EMPTY_OBJECT);
              var materialsCommon = extensions.KHR_materials_common;
              if (defined(materialsCommon)) {
                  var technique = materialsCommon.technique;
                  var values = defined(materialsCommon.values) ? materialsCommon.values : {};
                  materialsCommon.values = values;

                  values.ambient = defined(values.ambient) ? values.ambient : [0.0, 0.0, 0.0, 1.0];
                  values.emission = defined(values.emission) ? values.emission : [0.0, 0.0, 0.0, 1.0];

                  values.transparency = defaultValue(values.transparency, 1.0);
                  values.transparent = defaultValue(values.transparent, false);
                  values.doubleSided = defaultValue(values.doubleSided, false);

                  if (technique !== 'CONSTANT') {
                      values.diffuse = defined(values.diffuse) ? values.diffuse : [0.0, 0.0, 0.0, 1.0];
                      if (technique !== 'LAMBERT') {
                          values.specular = defined(values.specular) ? values.specular : [0.0, 0.0, 0.0, 1.0];
                          values.shininess = defaultValue(values.shininess, 0.0);
                      }
                  }
                  return;
              }

              material.emissiveFactor = defaultValue(material.emissiveFactor, [0.0, 0.0, 0.0]);
              material.alphaMode = defaultValue(material.alphaMode, 'OPAQUE');
              material.doubleSided = defaultValue(material.doubleSided, false);

              if (material.alphaMode === 'MASK') {
                  material.alphaCutoff = defaultValue(material.alphaCutoff, 0.5);
              }

              var techniquesExtension = extensions.KHR_techniques_webgl;
              if (defined(techniquesExtension)) {
                  ForEach.materialValue(material, function (materialValue) {
                      // Check if material value is a TextureInfo object
                      if (defined(materialValue.index)) {
                          addTextureDefaults(materialValue);
                      }
                  });
              }

              addTextureDefaults(material.emissiveTexture);
              addTextureDefaults(material.normalTexture);
              addTextureDefaults(material.occlusionTexture);

              var pbrMetallicRoughness = material.pbrMetallicRoughness;
              if (defined(pbrMetallicRoughness)) {
                  pbrMetallicRoughness.baseColorFactor = defaultValue(pbrMetallicRoughness.baseColorFactor, [1.0, 1.0, 1.0, 1.0]);
                  pbrMetallicRoughness.metallicFactor = defaultValue(pbrMetallicRoughness.metallicFactor, 1.0);
                  pbrMetallicRoughness.roughnessFactor = defaultValue(pbrMetallicRoughness.roughnessFactor, 1.0);
                  addTextureDefaults(pbrMetallicRoughness.baseColorTexture);
                  addTextureDefaults(pbrMetallicRoughness.metallicRoughnessTexture);
              }

              var pbrSpecularGlossiness = extensions.pbrSpecularGlossiness;
              if (defined(pbrSpecularGlossiness)) {
                  pbrSpecularGlossiness.diffuseFactor = defaultValue(pbrSpecularGlossiness.diffuseFactor, [1.0, 1.0, 1.0, 1.0]);
                  pbrSpecularGlossiness.specularFactor = defaultValue(pbrSpecularGlossiness.specularFactor, [1.0, 1.0, 1.0]);
                  pbrSpecularGlossiness.glossinessFactor = defaultValue(pbrSpecularGlossiness.glossinessFactor, 1.0);
                  addTextureDefaults(pbrSpecularGlossiness.specularGlossinessTexture);
              }
          });

          ForEach.animation(gltf, function(animation) {
              ForEach.animationSampler(animation, function(sampler) {
                  sampler.interpolation = defaultValue(sampler.interpolation, 'LINEAR');
              });
          });

          var animatedNodes = getAnimatedNodes(gltf);
          ForEach.node(gltf, function(node, id) {
              var animated = defined(animatedNodes[id]);
              if (animated || defined(node.translation) || defined(node.rotation) || defined(node.scale)) {
                  node.translation = defaultValue(node.translation, [0.0, 0.0, 0.0]);
                  node.rotation = defaultValue(node.rotation, [0.0, 0.0, 0.0, 1.0]);
                  node.scale = defaultValue(node.scale, [1.0, 1.0, 1.0]);
              } else {
                  node.matrix = defaultValue(node.matrix, [1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0]);
              }
          });

          ForEach.sampler(gltf, function(sampler) {
              sampler.wrapS = defaultValue(sampler.wrapS, WebGLConstants$1.REPEAT);
              sampler.wrapT = defaultValue(sampler.wrapT, WebGLConstants$1.REPEAT);
          });

          if (defined(gltf.scenes) && !defined(gltf.scene)) {
              gltf.scene = 0;
          }

          return gltf;
      }

      function getAnimatedNodes(gltf) {
          var nodes = {};
          ForEach.animation(gltf, function(animation) {
              ForEach.animationChannel(animation, function(channel) {
                  var target = channel.target;
                  var nodeId = target.node;
                  var path = target.path;
                  // Ignore animations that target 'weights'
                  if (path === 'translation' || path === 'rotation' || path === 'scale') {
                      nodes[nodeId] = true;
                  }
              });
          });
          return nodes;
      }

      function addTextureDefaults(texture) {
          if (defined(texture)) {
              texture.texCoord = defaultValue(texture.texCoord, 0);
          }
      }

  /**
       * Adds extras._pipeline to each object that can have extras in the glTF asset.
       * This stage runs before updateVersion and handles both glTF 1.0 and glTF 2.0 assets.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @returns {Object} The glTF asset with the added pipeline extras.
       *
       * @private
       */
      function addPipelineExtras(gltf) {
          ForEach.shader(gltf, function(shader) {
              addExtras(shader);
          });
          ForEach.buffer(gltf, function(buffer) {
              addExtras(buffer);
          });
          ForEach.image(gltf, function (image) {
              addExtras(image);
              ForEach.compressedImage(image, function(compressedImage) {
                  addExtras(compressedImage);
              });
          });

          addExtras(gltf);

          return gltf;
      }

      function addExtras(object) {
          object.extras = defined(object.extras) ? object.extras : {};
          object.extras._pipeline = defined(object.extras._pipeline) ? object.extras._pipeline : {};
      }

  /**
       * Removes an extension from gltf.extensionsRequired if it is present.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {String} extension The extension to remove.
       *
       * @private
       */
      function removeExtensionsRequired(gltf, extension) {
          var extensionsRequired = gltf.extensionsRequired;
          if (defined(extensionsRequired)) {
              var index = extensionsRequired.indexOf(extension);
              if (index >= 0) {
                  extensionsRequired.splice(index, 1);
              }
              if (extensionsRequired.length === 0) {
                  delete gltf.extensionsRequired;
              }
          }
      }

  /**
       * Removes an extension from gltf.extensionsUsed and gltf.extensionsRequired if it is present.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {String} extension The extension to remove.
       *
       * @private
       */
      function removeExtensionsUsed(gltf, extension) {
          var extensionsUsed = gltf.extensionsUsed;
          if (defined(extensionsUsed)) {
              var index = extensionsUsed.indexOf(extension);
              if (index >= 0) {
                  extensionsUsed.splice(index, 1);
              }
              removeExtensionsRequired(gltf, extension);
              if (extensionsUsed.length === 0) {
                  delete gltf.extensionsUsed;
              }
          }
      }

  var sizeOfUint32$2 = 4;

      /**
       * Convert a binary glTF to glTF.
       *
       * The returned glTF has pipeline extras included. The embedded binary data is stored in gltf.buffers[0].extras._pipeline.source.
       *
       * @param {Buffer} glb The glb data to parse.
       * @returns {Object} A javascript object containing a glTF asset with pipeline extras included.
       *
       * @private
       */
      function parseGlb(glb) {
          // Check that the magic string is present
          var magic = getMagic(glb);
          if (magic !== 'glTF') {
              throw new RuntimeError('File is not valid binary glTF');
          }

          var header = readHeader(glb, 0, 5);
          var version = header[1];
          if (version !== 1 && version !== 2) {
              throw new RuntimeError('Binary glTF version is not 1 or 2');
          }

          if (version === 1) {
              return parseGlbVersion1(glb, header);
          }

          return parseGlbVersion2(glb, header);
      }

      function readHeader(glb, byteOffset, count) {
          var dataView = new DataView(glb.buffer);
          var header = new Array(count);
          for (var i = 0; i < count; ++i) {
              header[i] = dataView.getUint32(glb.byteOffset + byteOffset + i * sizeOfUint32$2, true);
          }
          return header;
      }

      function parseGlbVersion1(glb, header) {
          var length = header[2];
          var contentLength = header[3];
          var contentFormat = header[4];

          // Check that the content format is 0, indicating that it is JSON
          if (contentFormat !== 0) {
              throw new RuntimeError('Binary glTF scene format is not JSON');
          }

          var jsonStart = 20;
          var binaryStart = jsonStart + contentLength;

          var contentString = getStringFromTypedArray(glb, jsonStart, contentLength);
          var gltf = JSON.parse(contentString);
          addPipelineExtras(gltf);

          var binaryBuffer = glb.subarray(binaryStart, length);

          var buffers = gltf.buffers;
          if (defined(buffers) && Object.keys(buffers).length > 0) {
              // In some older models, the binary glTF buffer is named KHR_binary_glTF
              var binaryGltfBuffer = defaultValue(buffers.binary_glTF, buffers.KHR_binary_glTF);
              if (defined(binaryGltfBuffer)) {
                  binaryGltfBuffer.extras._pipeline.source = binaryBuffer;
              }
          }
          // Remove the KHR_binary_glTF extension
          removeExtensionsUsed(gltf, 'KHR_binary_glTF');
          return gltf;
      }

      function parseGlbVersion2(glb, header) {
          var length = header[2];
          var byteOffset = 12;
          var gltf;
          var binaryBuffer;
          while (byteOffset < length) {
              var chunkHeader = readHeader(glb, byteOffset, 2);
              var chunkLength = chunkHeader[0];
              var chunkType = chunkHeader[1];
              byteOffset += 8;
              var chunkBuffer = glb.subarray(byteOffset, byteOffset + chunkLength);
              byteOffset += chunkLength;
              // Load JSON chunk
              if (chunkType === 0x4E4F534A) {
                  var jsonString = getStringFromTypedArray(chunkBuffer);
                  gltf = JSON.parse(jsonString);
                  addPipelineExtras(gltf);
              }
              // Load Binary chunk
              else if (chunkType === 0x004E4942) {
                  binaryBuffer = chunkBuffer;
              }
          }
          if (defined(gltf) && defined(binaryBuffer)) {
              var buffers = gltf.buffers;
              if (defined(buffers) && buffers.length > 0) {
                  var buffer = buffers[0];
                  buffer.extras._pipeline.source = binaryBuffer;
              }
          }
          return gltf;
      }

  /**
       * Adds an extension to gltf.extensionsUsed if it does not already exist.
       * Initializes extensionsUsed if it is not defined.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {String} extension The extension to add.
       *
       * @private
       */
      function addExtensionsUsed(gltf, extension) {
          var extensionsUsed = gltf.extensionsUsed;
          if (!defined(extensionsUsed)) {
              extensionsUsed = [];
              gltf.extensionsUsed = extensionsUsed;
          }
          addToArray(extensionsUsed, extension, true);
      }

  /**
       * Returns a function to read and convert data from a DataView into an array.
       *
       * @param {Number} componentType Type to convert the data to.
       * @returns {ComponentReader} Function that reads and converts data.
       *
       * @private
       */
      function getComponentReader(componentType) {
          switch (componentType) {
              case ComponentDatatype$1.BYTE:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getInt8(byteOffset + i * componentTypeByteLength);
                      }
                  };
              case ComponentDatatype$1.UNSIGNED_BYTE:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getUint8(byteOffset + i * componentTypeByteLength);
                      }
                  };
              case ComponentDatatype$1.SHORT:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getInt16(byteOffset + i * componentTypeByteLength, true);
                      }
                  };
              case ComponentDatatype$1.UNSIGNED_SHORT:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getUint16(byteOffset + i * componentTypeByteLength, true);
                      }
                  };
              case ComponentDatatype$1.INT:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getInt32(byteOffset + i * componentTypeByteLength, true);
                      }
                  };
              case ComponentDatatype$1.UNSIGNED_INT:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getUint32(byteOffset + i * componentTypeByteLength, true);
                      }
                  };
              case ComponentDatatype$1.FLOAT:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getFloat32(byteOffset + i * componentTypeByteLength, true);
                      }
                  };
              case ComponentDatatype$1.DOUBLE:
                  return function (dataView, byteOffset, numberOfComponents, componentTypeByteLength, result) {
                      for (var i = 0; i < numberOfComponents; ++i) {
                          result[i] = dataView.getFloat64(byteOffset + i * componentTypeByteLength, true);
                      }
                  };
          }
      }

  /**
       * Finds the min and max values of the accessor.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {Object} accessor The accessor object from the glTF asset to read.
       * @returns {{min: Array, max: Array}} min holding the array of minimum values and max holding the array of maximum values.
       *
       * @private
       */
      function findAccessorMinMax(gltf, accessor) {
          var bufferViews = gltf.bufferViews;
          var buffers = gltf.buffers;
          var bufferViewId = accessor.bufferView;
          var numberOfComponents = numberOfComponentsForType(accessor.type);

          // According to the spec, when bufferView is not defined, accessor must be initialized with zeros
          if (!defined(accessor.bufferView)) {
              return {
                  min: arrayFill(new Array(numberOfComponents), 0.0),
                  max: arrayFill(new Array(numberOfComponents), 0.0)
              };
          }

          var min = arrayFill(new Array(numberOfComponents), Number.POSITIVE_INFINITY);
          var max = arrayFill(new Array(numberOfComponents), Number.NEGATIVE_INFINITY);

          var bufferView = bufferViews[bufferViewId];
          var bufferId = bufferView.buffer;
          var buffer = buffers[bufferId];
          var source = buffer.extras._pipeline.source;

          var count = accessor.count;
          var byteStride = getAccessorByteStride(gltf, accessor);
          var byteOffset = accessor.byteOffset + bufferView.byteOffset + source.byteOffset;
          var componentType = accessor.componentType;
          var componentTypeByteLength = ComponentDatatype$1.getSizeInBytes(componentType);
          var dataView = new DataView(source.buffer);
          var components = new Array(numberOfComponents);
          var componentReader = getComponentReader(componentType);

          for (var i = 0; i < count; i++) {
              componentReader(dataView, byteOffset, numberOfComponents, componentTypeByteLength, components);
              for (var j = 0; j < numberOfComponents; j++) {
                  var value = components[j];
                  min[j] = Math.min(min[j], value);
                  max[j] = Math.max(max[j], value);
              }
              byteOffset += byteStride;
          }

          return {
              min: min,
              max: max
          };
      }

  var defaultBlendEquation = [
          WebGLConstants$1.FUNC_ADD,
          WebGLConstants$1.FUNC_ADD
      ];

      var defaultBlendFactors = [
          WebGLConstants$1.ONE,
          WebGLConstants$1.ZERO,
          WebGLConstants$1.ONE,
          WebGLConstants$1.ZERO
      ];

      function isStateEnabled(renderStates, state) {
          var enabled = renderStates.enable;
          if (!defined(enabled)) {
              return false;
          }

          return (enabled.indexOf(state) > -1);
      }

      var supportedBlendFactors = [
          WebGLConstants$1.ZERO,
          WebGLConstants$1.ONE,
          WebGLConstants$1.SRC_COLOR,
          WebGLConstants$1.ONE_MINUS_SRC_COLOR,
          WebGLConstants$1.SRC_ALPHA,
          WebGLConstants$1.ONE_MINUS_SRC_ALPHA,
          WebGLConstants$1.DST_ALPHA,
          WebGLConstants$1.ONE_MINUS_DST_ALPHA,
          WebGLConstants$1.DST_COLOR,
          WebGLConstants$1.ONE_MINUS_DST_COLOR
      ];

      // If any of the blend factors are not supported, return the default
      function getSupportedBlendFactors(value, defaultValue) {
          if (!defined(value)) {
              return defaultValue;
          }

          for (var i = 0; i < 4; i++) {
              if (supportedBlendFactors.indexOf(value[i]) === -1) {
                  return defaultValue;
              }
          }

          return value;
      }

      /**
       * Move glTF 1.0 technique render states to glTF 2.0 materials properties and KHR_blend extension.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @returns {Object} The updated glTF asset.
       *
       * @private
       */
      function moveTechniqueRenderStates(gltf) {
          var blendingForTechnique = {};
          var materialPropertiesForTechnique = {};
          var techniquesLegacy = gltf.techniques;
          if (!defined(techniquesLegacy)) {
              return gltf;
          }

          ForEach.technique(gltf, function (techniqueLegacy, techniqueIndex) {
              var renderStates = techniqueLegacy.states;
              if (defined(renderStates)) {
                  var materialProperties = materialPropertiesForTechnique[techniqueIndex] = {};

                  // If BLEND is enabled, the material should have alpha mode BLEND
                  if (isStateEnabled(renderStates, WebGLConstants$1.BLEND)) {
                      materialProperties.alphaMode = 'BLEND';

                      var blendFunctions = renderStates.functions;
                      if (defined(blendFunctions) && (defined(blendFunctions.blendEquationSeparate)
                              || defined(blendFunctions.blendFuncSeparate))) {
                          blendingForTechnique[techniqueIndex] = {
                              blendEquation: defaultValue(blendFunctions.blendEquationSeparate, defaultBlendEquation),
                              blendFactors: getSupportedBlendFactors(blendFunctions.blendFuncSeparate, defaultBlendFactors)
                          };
                      }
                  }

                  // If CULL_FACE is not enabled, the material should be doubleSided
                  if (!isStateEnabled(renderStates, WebGLConstants$1.CULL_FACE)) {
                      materialProperties.doubleSided = true;
                  }

                  delete techniqueLegacy.states;
              }
          });

          if (Object.keys(blendingForTechnique).length > 0) {
              if (!defined(gltf.extensions)) {
                  gltf.extensions = {};
              }

              addExtensionsUsed(gltf, 'KHR_blend');
          }

          ForEach.material(gltf, function (material) {
              if (defined(material.technique)) {
                  var materialProperties = materialPropertiesForTechnique[material.technique];
                  ForEach.objectLegacy(materialProperties, function (value, property) {
                      material[property] = value;
                  });

                  var blending = blendingForTechnique[material.technique];
                  if (defined(blending)) {
                      if (!defined(material.extensions)) {
                          material.extensions = {};
                      }

                      material.extensions.KHR_blend = blending;
                  }
              }
          });

          return gltf;
      }

  /**
       * Adds an extension to gltf.extensionsRequired if it does not already exist.
       * Initializes extensionsRequired if it is not defined.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {String} extension The extension to add.
       *
       * @private
       */
      function addExtensionsRequired(gltf, extension) {
          var extensionsRequired = gltf.extensionsRequired;
          if (!defined(extensionsRequired)) {
              extensionsRequired = [];
              gltf.extensionsRequired = extensionsRequired;
          }
          addToArray(extensionsRequired, extension, true);
          addExtensionsUsed(gltf, extension);
      }

  /**
       * Move glTF 1.0 material techniques to glTF 2.0 KHR_techniques_webgl extension.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @returns {Object} The updated glTF asset.
       *
       * @private
       */
      function moveTechniquesToExtension(gltf) {
          var techniquesLegacy = gltf.techniques;
          var mappedUniforms = {};
          var updatedTechniqueIndices = {};
          if (defined(techniquesLegacy)) {
              var extension = {
                  programs: [],
                  shaders: [],
                  techniques: []
              };

              // Some 1.1 models have a glExtensionsUsed property that can be transferred to program.glExtensions
              var glExtensions = gltf.glExtensionsUsed;
              delete gltf.glExtensionsUsed;

              ForEach.technique(gltf, function (techniqueLegacy, techniqueIndex) {
                  var technique = {
                      name: techniqueLegacy.name,
                      program: undefined,
                      attributes: {},
                      uniforms: {}
                  };

                  var parameterLegacy;
                  ForEach.techniqueAttribute(techniqueLegacy, function (parameterName, attributeName) {
                      parameterLegacy = techniqueLegacy.parameters[parameterName];
                      technique.attributes[attributeName] = {
                          semantic: parameterLegacy.semantic
                      };
                  });

                  ForEach.techniqueUniform(techniqueLegacy, function (parameterName, uniformName) {
                      parameterLegacy = techniqueLegacy.parameters[parameterName];
                      technique.uniforms[uniformName] = {
                          count: parameterLegacy.count,
                          node: parameterLegacy.node,
                          type: parameterLegacy.type,
                          semantic: parameterLegacy.semantic,
                          value: parameterLegacy.value
                      };

                      // Store the name of the uniform to update material values.
                      mappedUniforms[parameterName] = uniformName;
                  });

                  var programLegacy = gltf.programs[techniqueLegacy.program];
                  var program = {
                      name: programLegacy.name,
                      fragmentShader: undefined,
                      vertexShader: undefined,
                      glExtensions: glExtensions
                  };

                  var fs = gltf.shaders[programLegacy.fragmentShader];
                  program.fragmentShader = addToArray(extension.shaders, fs, true);

                  var vs = gltf.shaders[programLegacy.vertexShader];
                  program.vertexShader = addToArray(extension.shaders, vs, true);

                  technique.program = addToArray(extension.programs, program);

                  // Store the index of the new technique to reference instead.
                  updatedTechniqueIndices[techniqueIndex] = addToArray(extension.techniques, technique);
              });

              if (extension.techniques.length > 0) {
                  if (!defined(gltf.extensions)) {
                      gltf.extensions = {};
                  }

                  gltf.extensions.KHR_techniques_webgl = extension;
                  addExtensionsUsed(gltf, 'KHR_techniques_webgl');
                  addExtensionsRequired(gltf, 'KHR_techniques_webgl');
              }
          }

          ForEach.material(gltf, function (material) {
              if (defined(material.technique)) {
                  var materialExtension = {
                      technique: updatedTechniqueIndices[material.technique]
                  };

                  ForEach.objectLegacy(material.values, function (value, parameterName) {
                      if (!defined(materialExtension.values)) {
                          materialExtension.values = {};
                      }

                      var uniformName = mappedUniforms[parameterName];
                      materialExtension.values[uniformName] = value;
                  });

                  if (!defined(material.extensions)) {
                      material.extensions = {};
                  }

                  material.extensions.KHR_techniques_webgl = materialExtension;
              }

              delete material.technique;
              delete material.values;
          });

          delete gltf.techniques;
          delete gltf.programs;
          delete gltf.shaders;

          return gltf;
      }

  var allElementTypes = ['mesh', 'node', 'material', 'accessor', 'bufferView', 'buffer'];

      /**
       * Removes unused elements from gltf.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {String[]} [elementTypes=['mesh', 'node', 'material', 'accessor', 'bufferView', 'buffer']] Element types to be removed. Needs to be a subset of ['mesh', 'node', 'material', 'accessor', 'bufferView', 'buffer'], other items will be ignored.
       *
       * @private
       */
      function removeUnusedElements(gltf, elementTypes) {
          elementTypes = defaultValue(elementTypes, allElementTypes);
          allElementTypes.forEach(function(type) {
              if (elementTypes.indexOf(type) > -1) {
                  removeUnusedElementsByType(gltf, type);
              }
          });
          return gltf;
      }

      var TypeToGltfElementName = {
          accessor: 'accessors',
          buffer: 'buffers',
          bufferView: 'bufferViews',
          node: 'nodes',
          material: 'materials',
          mesh: 'meshes'
      };

      function removeUnusedElementsByType(gltf, type) {
          var name = TypeToGltfElementName[type];
          var arrayOfObjects = gltf[name];

          if (defined(arrayOfObjects)) {
              var removed = 0;
              var usedIds = getListOfElementsIdsInUse[type](gltf);
              var length = arrayOfObjects.length;

              for (var i = 0; i < length; ++i) {
                  if (!usedIds[i]) {
                      Remove[type](gltf, i - removed);
                      removed++;
                  }
              }
          }
      }

      /**
       * Contains functions for removing elements from a glTF hierarchy.
       * Since top-level glTF elements are arrays, when something is removed, referring
       * indices need to be updated.
       * @constructor
       *
       * @private
       */
      function Remove() {}

      Remove.accessor = function(gltf, accessorId) {
          var accessors = gltf.accessors;

          accessors.splice(accessorId, 1);

          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  // Update accessor ids for the primitives.
                  ForEach.meshPrimitiveAttribute(primitive, function(attributeAccessorId, semantic) {
                      if (attributeAccessorId > accessorId) {
                          primitive.attributes[semantic]--;
                      }
                  });

                  // Update accessor ids for the targets.
                  ForEach.meshPrimitiveTarget(primitive, function(target) {
                      ForEach.meshPrimitiveTargetAttribute(target, function(attributeAccessorId, semantic) {
                          if (attributeAccessorId > accessorId) {
                              target[semantic]--;
                          }
                      });
                  });
                  var indices = primitive.indices;
                  if (defined(indices) && indices > accessorId) {
                      primitive.indices--;
                  }
              });
          });

          ForEach.skin(gltf, function(skin) {
              if (defined(skin.inverseBindMatrices) && skin.inverseBindMatrices > accessorId) {
                  skin.inverseBindMatrices--;
              }
          });

          ForEach.animation(gltf, function(animation) {
              ForEach.animationSampler(animation, function(sampler) {
                  if (defined(sampler.input) && sampler.input > accessorId) {
                      sampler.input--;
                  }
                  if (defined(sampler.output) && sampler.output > accessorId) {
                      sampler.output--;
                  }
              });
          });
      };

      Remove.buffer = function(gltf, bufferId) {
          var buffers = gltf.buffers;

          buffers.splice(bufferId, 1);

          ForEach.bufferView(gltf, function(bufferView) {
              if (defined(bufferView.buffer) && bufferView.buffer > bufferId) {
                  bufferView.buffer--;
              }
          });
      };

      Remove.bufferView = function(gltf, bufferViewId) {
          var bufferViews = gltf.bufferViews;

          bufferViews.splice(bufferViewId, 1);

          ForEach.accessor(gltf, function(accessor) {
              if (defined(accessor.bufferView) && accessor.bufferView > bufferViewId) {
                  accessor.bufferView--;
              }
          });

          ForEach.shader(gltf, function(shader) {
              if (defined(shader.bufferView) && shader.bufferView > bufferViewId) {
                  shader.bufferView--;
              }
          });

          ForEach.image(gltf, function(image) {
              if (defined(image.bufferView) && image.bufferView > bufferViewId) {
                  image.bufferView--;
              }
              ForEach.compressedImage(image, function(compressedImage) {
                  var compressedImageBufferView = compressedImage.bufferView;
                  if (defined(compressedImageBufferView) && compressedImageBufferView > bufferViewId) {
                      compressedImage.bufferView--;
                  }
              });
          });

          if (hasExtension(gltf, 'KHR_draco_mesh_compression')) {
              ForEach.mesh(gltf, function(mesh) {
                  ForEach.meshPrimitive(mesh, function(primitive) {
                      if (defined(primitive.extensions) &&
                          defined(primitive.extensions.KHR_draco_mesh_compression)) {
                          if (primitive.extensions.KHR_draco_mesh_compression.bufferView > bufferViewId) {
                              primitive.extensions.KHR_draco_mesh_compression.bufferView--;
                          }
                      }
                  });
              });
          }
      };

      Remove.mesh = function(gltf, meshId) {
          var meshes = gltf.meshes;
          meshes.splice(meshId, 1);

          ForEach.node(gltf, function(node) {
              if (defined(node.mesh)) {
                  if (node.mesh > meshId) {
                      node.mesh--;
                  } else if (node.mesh === meshId) {
                      // Remove reference to deleted mesh
                      delete node.mesh;
                  }
              }
          });
      };

      Remove.node = function(gltf, nodeId) {
          var nodes = gltf.nodes;
          nodes.splice(nodeId, 1);

          // Shift all node references
          ForEach.skin(gltf, function(skin) {
              if (defined(skin.skeleton) && skin.skeleton > nodeId) {
                  skin.skeleton--;
              }

              skin.joints = skin.joints.map(function(x) {
                  return x > nodeId ? x - 1 : x;
              });
          });
          ForEach.animation(gltf, function(animation) {
              ForEach.animationChannel(animation, function(channel) {
                  if (defined(channel.target) && defined(channel.target.node) && (channel.target.node > nodeId)) {
                      channel.target.node--;
                  }
              });
          });
          ForEach.technique(gltf, function(technique) {
              ForEach.techniqueUniform(technique, function(uniform) {
                  if (defined(uniform.node) && uniform.node > nodeId) {
                      uniform.node--;
                  }
              });
          });
          ForEach.node(gltf, function(node) {
              if (!defined(node.children)) {
                  return;
              }

              node.children = node.children
                  .filter(function(x) {
                      return x !== nodeId; // Remove
                  })
                  .map(function(x) {
                      return x > nodeId ? x - 1 : x; // Shift indices
                  });
          });
          ForEach.scene(gltf, function(scene) {
              scene.nodes = scene.nodes
                  .filter(function(x) {
                      return x !== nodeId; // Remove
                  })
                  .map(function(x) {
                      return x > nodeId ? x - 1 : x; // Shift indices
                  });
          });
      };

      Remove.material = function(gltf, materialId) {
          var materials = gltf.materials;
          materials.splice(materialId, 1);

          // Shift other material ids
          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  if (defined(primitive.material) && primitive.material > materialId) {
                      primitive.material--;
                  }
              });
          });
      };

      /**
       * Contains functions for getting a list of element ids in use by the glTF asset.
       * @constructor
       *
       * @private
       */
      function getListOfElementsIdsInUse() {}

      getListOfElementsIdsInUse.accessor = function(gltf) {
          // Calculate accessor's that are currently in use.
          var usedAccessorIds = {};

          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  ForEach.meshPrimitiveAttribute(primitive, function(accessorId) {
                      usedAccessorIds[accessorId] = true;
                  });
                  ForEach.meshPrimitiveTarget(primitive, function(target) {
                      ForEach.meshPrimitiveTargetAttribute(target, function(accessorId) {
                          usedAccessorIds[accessorId] = true;
                      });
                  });
                  var indices = primitive.indices;
                  if (defined(indices)) {
                      usedAccessorIds[indices] = true;
                  }
              });
          });

          ForEach.skin(gltf, function(skin) {
              if (defined(skin.inverseBindMatrices)) {
                  usedAccessorIds[skin.inverseBindMatrices] = true;
              }
          });

          ForEach.animation(gltf, function(animation) {
              ForEach.animationSampler(animation, function(sampler) {
                  if (defined(sampler.input)) {
                      usedAccessorIds[sampler.input] = true;
                  }
                  if (defined(sampler.output)) {
                      usedAccessorIds[sampler.output] = true;
                  }
              });
          });

          return usedAccessorIds;
      };

      getListOfElementsIdsInUse.buffer = function(gltf) {
          // Calculate buffer's that are currently in use.
          var usedBufferIds = {};

          ForEach.bufferView(gltf, function(bufferView) {
              if (defined(bufferView.buffer)) {
                  usedBufferIds[bufferView.buffer] = true;
              }
          });

          return usedBufferIds;
      };

      getListOfElementsIdsInUse.bufferView = function(gltf) {
          // Calculate bufferView's that are currently in use.
          var usedBufferViewIds = {};

          ForEach.accessor(gltf, function(accessor) {
              if (defined(accessor.bufferView)) {
                  usedBufferViewIds[accessor.bufferView] = true;
              }
          });

          ForEach.shader(gltf, function(shader) {
              if (defined(shader.bufferView)) {
                  usedBufferViewIds[shader.bufferView] = true;
              }
          });

          ForEach.image(gltf, function(image) {
              if (defined(image.bufferView)) {
                  usedBufferViewIds[image.bufferView] = true;
              }
              ForEach.compressedImage(image, function(compressedImage) {
                  if (defined(compressedImage.bufferView)) {
                      usedBufferViewIds[compressedImage.bufferView] = true;
                  }
              });
          });

          if (hasExtension(gltf, 'KHR_draco_mesh_compression')) {
              ForEach.mesh(gltf, function(mesh) {
                  ForEach.meshPrimitive(mesh, function(primitive) {
                      if (defined(primitive.extensions) &&
                          defined(primitive.extensions.KHR_draco_mesh_compression)) {
                          usedBufferViewIds[primitive.extensions.KHR_draco_mesh_compression.bufferView] = true;
                      }
                  });
              });
          }

          return usedBufferViewIds;
      };

      getListOfElementsIdsInUse.mesh = function(gltf) {
          var usedMeshIds = {};
          ForEach.node(gltf, function(node) {
              if (defined(node.mesh && defined(gltf.meshes))) {
                  var mesh = gltf.meshes[node.mesh];
                  if (defined(mesh) && defined(mesh.primitives) && (mesh.primitives.length > 0)) {
                      usedMeshIds[node.mesh] = true;
                  }
              }
          });

          return usedMeshIds;
      };

      // Check if node is empty. It is considered empty if neither referencing
      // mesh, camera, extensions and has no children
      function nodeIsEmpty(gltf, node) {
          if (defined(node.mesh) || defined(node.camera) || defined(node.skin)
              || defined(node.weights) || defined(node.extras)
              || (defined(node.extensions) && node.extensions.length !== 0)) {
              return false;
          }

          // Empty if no children or children are all empty nodes
          return !defined(node.children)
              || node.children.filter(function(n) {
                  return !nodeIsEmpty(gltf, gltf.nodes[n]);
              }).length === 0;
      }

      getListOfElementsIdsInUse.node = function(gltf) {
          var usedNodeIds = {};
          ForEach.node(gltf, function(node, nodeId) {
              if (!nodeIsEmpty(gltf, node)) {
                  usedNodeIds[nodeId] = true;
              }
          });
          ForEach.skin(gltf, function(skin) {
              if (defined(skin.skeleton)) {
                  usedNodeIds[skin.skeleton] = true;
              }

              ForEach.skinJoint(skin, function(joint) {
                  usedNodeIds[joint] = true;
              });
          });
          ForEach.animation(gltf, function(animation) {
              ForEach.animationChannel(animation, function(channel) {
                  if (defined(channel.target) && defined(channel.target.node)) {
                      usedNodeIds[channel.target.node] = true;
                  }
              });
          });
          ForEach.technique(gltf, function(technique) {
              ForEach.techniqueUniform(technique, function(uniform) {
                  if (defined(uniform.node)) {
                      usedNodeIds[uniform.node] = true;
                  }
              });
          });

          return usedNodeIds;
      };

      getListOfElementsIdsInUse.material = function(gltf) {
          var usedMaterialIds = {};

          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  if (defined(primitive.material)) {
                      usedMaterialIds[primitive.material] = true;
                  }
              });
          });

          return usedMaterialIds;
      };

  /**
       * Adds buffer to gltf.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {Buffer} buffer A Buffer object which will be added to gltf.buffers.
       * @returns {Number} The bufferView id of the newly added bufferView.
       *
       * @private
       */
      function addBuffer(gltf, buffer) {
          var newBuffer = {
              byteLength: buffer.length,
              extras: {
                  _pipeline: {
                      source: buffer
                  }
              }
          };
          var bufferId = addToArray(gltf.buffers, newBuffer);
          var bufferView = {
              buffer: bufferId,
              byteOffset: 0,
              byteLength: buffer.length
          };
          return addToArray(gltf.bufferViews, bufferView);
      }

  /**
       * Returns the accessor data in a contiguous array.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {Object} accessor The accessor.
       * @returns {Array} The accessor values in a contiguous array.
       *
       * @private
       */
      function readAccessorPacked(gltf, accessor) {
          var byteStride = getAccessorByteStride(gltf, accessor);
          var componentTypeByteLength = ComponentDatatype$1.getSizeInBytes(accessor.componentType);
          var numberOfComponents = numberOfComponentsForType(accessor.type);
          var count = accessor.count;
          var values = new Array(numberOfComponents * count);

          if (!defined(accessor.bufferView)) {
              arrayFill(values, 0);
              return values;
          }

          var bufferView = gltf.bufferViews[accessor.bufferView];
          var source = gltf.buffers[bufferView.buffer].extras._pipeline.source;
          var byteOffset = accessor.byteOffset + bufferView.byteOffset + source.byteOffset;

          var dataView = new DataView(source.buffer);
          var components = new Array(numberOfComponents);
          var componentReader = getComponentReader(accessor.componentType);

          for (var i = 0; i < count; ++i) {
              componentReader(dataView, byteOffset, numberOfComponents, componentTypeByteLength, components);
              for (var j = 0; j < numberOfComponents; ++j) {
                  values[i * numberOfComponents + j] = components[j];
              }
              byteOffset += byteStride;
          }
          return values;
      }

  /**
       * Update accessors referenced by JOINTS_0 and WEIGHTS_0 attributes to use correct component types.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @returns {Object} The glTF asset with compressed meshes.
       *
       * @private
       */
      function updateAccessorComponentTypes(gltf) {
          var componentType;
          ForEach.accessorWithSemantic(gltf, 'JOINTS_0', function(accessorId) {
              var accessor = gltf.accessors[accessorId];
              componentType = accessor.componentType;
              if (componentType === WebGLConstants$1.BYTE) {
                  convertType(gltf, accessor, ComponentDatatype$1.UNSIGNED_BYTE);
              } else if (componentType !== WebGLConstants$1.UNSIGNED_BYTE
                      && componentType !== WebGLConstants$1.UNSIGNED_SHORT) {
                  convertType(gltf, accessor, ComponentDatatype$1.UNSIGNED_SHORT);
              }
          });
          ForEach.accessorWithSemantic(gltf, 'WEIGHTS_0', function(accessorId) {
              var accessor = gltf.accessors[accessorId];
              componentType = accessor.componentType;
              if (componentType === WebGLConstants$1.BYTE) {
                  convertType(gltf, accessor, ComponentDatatype$1.UNSIGNED_BYTE);
              } else if (componentType === WebGLConstants$1.SHORT) {
                  convertType(gltf, accessor, ComponentDatatype$1.UNSIGNED_SHORT);
              }
          });

          return gltf;
      }

      function convertType(gltf, accessor, updatedComponentType) {
          var typedArray = ComponentDatatype$1.createTypedArray(updatedComponentType, readAccessorPacked(gltf, accessor));
          var newBuffer = new Uint8Array(typedArray.buffer);
          accessor.bufferView = addBuffer(gltf, newBuffer);
          accessor.componentType = updatedComponentType;
          accessor.byteOffset = 0;
      }

  var updateFunctions = {
          '0.8': glTF08to10,
          '1.0': glTF10to20,
          '2.0': undefined
      };

      /**
       * Update the glTF version to the latest version (2.0), or targetVersion if specified.
       * Applies changes made to the glTF spec between revisions so that the core library
       * only has to handle the latest version.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @param {Object} [options] Options for updating the glTF.
       * @param {String} [options.targetVersion] The glTF will be upgraded until it hits the specified version.
       * @returns {Object} The updated glTF asset.
       *
       * @private
       */
      function updateVersion(gltf, options) {
          options = defaultValue(options, defaultValue.EMPTY_OBJECT);
          var targetVersion = options.targetVersion;
          var version = gltf.version;

          gltf.asset = defaultValue(gltf.asset, {
              version: '1.0'
          });

          gltf.asset.version = defaultValue(gltf.asset.version, '1.0');
          version = defaultValue(version, gltf.asset.version).toString();

          // Invalid version
          if (!Object.prototype.hasOwnProperty.call(updateFunctions, version)) {
              // Try truncating trailing version numbers, could be a number as well if it is 0.8
              if (defined(version)) {
                  version = version.substring(0, 3);
              }
              // Default to 1.0 if it cannot be determined
              if (!Object.prototype.hasOwnProperty.call(updateFunctions, version)) {
                  version = '1.0';
              }
          }

          var updateFunction = updateFunctions[version];

          while (defined(updateFunction)) {
              if (version === targetVersion) {
                  break;
              }
              updateFunction(gltf, options);
              version = gltf.asset.version;
              updateFunction = updateFunctions[version];
          }
          return gltf;
      }

      function updateInstanceTechniques(gltf) {
          var materials = gltf.materials;
          for (var materialId in materials) {
              if (Object.prototype.hasOwnProperty.call(materials, materialId)) {
                  var material = materials[materialId];
                  var instanceTechnique = material.instanceTechnique;
                  if (defined(instanceTechnique)) {
                      material.technique = instanceTechnique.technique;
                      material.values = instanceTechnique.values;
                      delete material.instanceTechnique;
                  }
              }
          }
      }

      function setPrimitiveModes(gltf) {
          var meshes = gltf.meshes;
          for (var meshId in meshes) {
              if (Object.prototype.hasOwnProperty.call(meshes, meshId)) {
                  var mesh = meshes[meshId];
                  var primitives = mesh.primitives;
                  if (defined(primitives)) {
                      var primitivesLength = primitives.length;
                      for (var i = 0; i < primitivesLength; ++i) {
                          var primitive = primitives[i];
                          var defaultMode = defaultValue(primitive.primitive, WebGLConstants$1.TRIANGLES);
                          primitive.mode = defaultValue(primitive.mode, defaultMode);
                          delete primitive.primitive;
                      }
                  }
              }
          }
      }

      function updateNodes(gltf) {
          var nodes = gltf.nodes;
          var axis = new Cartesian3();
          var quat = new Quaternion();
          for (var nodeId in nodes) {
              if (Object.prototype.hasOwnProperty.call(nodes, nodeId)) {
                  var node = nodes[nodeId];
                  if (defined(node.rotation)) {
                      var rotation = node.rotation;
                      Cartesian3.fromArray(rotation, 0, axis);
                      Quaternion.fromAxisAngle(axis, rotation[3], quat);
                      node.rotation = [quat.x, quat.y, quat.z, quat.w];
                  }
                  var instanceSkin = node.instanceSkin;
                  if (defined(instanceSkin)) {
                      node.skeletons = instanceSkin.skeletons;
                      node.skin = instanceSkin.skin;
                      node.meshes = instanceSkin.meshes;
                      delete node.instanceSkin;
                  }
              }
          }
      }

      function updateAnimations(gltf) {
          var animations = gltf.animations;
          var accessors = gltf.accessors;
          var bufferViews = gltf.bufferViews;
          var buffers = gltf.buffers;
          var updatedAccessors = {};
          var axis = new Cartesian3();
          var quat = new Quaternion();
          for (var animationId in animations) {
              if (Object.prototype.hasOwnProperty.call(animations, animationId)) {
                  var animation = animations[animationId];
                  var channels = animation.channels;
                  var parameters = animation.parameters;
                  var samplers = animation.samplers;
                  if (defined(channels)) {
                      var channelsLength = channels.length;
                      for (var i = 0; i < channelsLength; ++i) {
                          var channel = channels[i];
                          if (channel.target.path === 'rotation') {
                              var accessorId = parameters[samplers[channel.sampler].output];
                              if (defined(updatedAccessors[accessorId])) {
                                  continue;
                              }
                              updatedAccessors[accessorId] = true;
                              var accessor = accessors[accessorId];
                              var bufferView = bufferViews[accessor.bufferView];
                              var buffer = buffers[bufferView.buffer];
                              var source = buffer.extras._pipeline.source;
                              var byteOffset = source.byteOffset + bufferView.byteOffset + accessor.byteOffset;
                              var componentType = accessor.componentType;
                              var count = accessor.count;
                              var componentsLength = numberOfComponentsForType(accessor.type);
                              var length = accessor.count * componentsLength;
                              var typedArray = ComponentDatatype$1.createArrayBufferView(componentType, source.buffer, byteOffset, length);

                              for (var j = 0; j < count; j++) {
                                  var offset = j * componentsLength;
                                  Cartesian3.unpack(typedArray, offset, axis);
                                  var angle = typedArray[offset + 3];
                                  Quaternion.fromAxisAngle(axis, angle, quat);
                                  Quaternion.pack(quat, typedArray, offset);
                              }
                          }
                      }
                  }
              }
          }
      }

      function removeTechniquePasses(gltf) {
          var techniques = gltf.techniques;
          for (var techniqueId in techniques) {
              if (Object.prototype.hasOwnProperty.call(techniques, techniqueId)) {
                  var technique = techniques[techniqueId];
                  var passes = technique.passes;
                  if (defined(passes)) {
                      var passName = defaultValue(technique.pass, 'defaultPass');
                      if (Object.prototype.hasOwnProperty.call(passes, passName)) {
                          var pass = passes[passName];
                          var instanceProgram = pass.instanceProgram;
                          technique.attributes = defaultValue(technique.attributes, instanceProgram.attributes);
                          technique.program = defaultValue(technique.program, instanceProgram.program);
                          technique.uniforms = defaultValue(technique.uniforms, instanceProgram.uniforms);
                          technique.states = defaultValue(technique.states, pass.states);
                      }
                      delete technique.passes;
                      delete technique.pass;
                  }
              }
          }
      }

      function glTF08to10(gltf) {
          if (!defined(gltf.asset)) {
              gltf.asset = {};
          }
          var asset = gltf.asset;
          asset.version = '1.0';
          // Profile should be an object, not a string
          if (typeof asset.profile === 'string') {
              var split = asset.profile.split(' ');
              asset.profile = {
                  api: split[0],
                  version: split[1]
              };
          } else {
              asset.profile = {};
          }

          // Version property should be in asset, not on the root element
          if (defined(gltf.version)) {
              delete gltf.version;
          }
          // material.instanceTechnique properties should be directly on the material
          updateInstanceTechniques(gltf);
          // primitive.primitive should be primitive.mode
          setPrimitiveModes(gltf);
          // Node rotation should be quaternion, not axis-angle
          // node.instanceSkin is deprecated
          updateNodes(gltf);
          // Animations that target rotations should be quaternion, not axis-angle
          updateAnimations(gltf);
          // technique.pass and techniques.passes are deprecated
          removeTechniquePasses(gltf);
          // gltf.allExtensions -> extensionsUsed
          if (defined(gltf.allExtensions)) {
              gltf.extensionsUsed = gltf.allExtensions;
              delete gltf.allExtensions;
          }
          // gltf.lights -> khrMaterialsCommon.lights
          if (defined(gltf.lights)) {
              var extensions = defaultValue(gltf.extensions, {});
              gltf.extensions = extensions;
              var materialsCommon = defaultValue(extensions.KHR_materials_common, {});
              extensions.KHR_materials_common = materialsCommon;
              materialsCommon.lights = gltf.lights;
              delete gltf.lights;
              addExtensionsUsed(gltf, 'KHR_materials_common');
          }
      }

      function removeAnimationSamplersIndirection(gltf) {
          var animations = gltf.animations;
          for (var animationId in animations) {
              if (Object.prototype.hasOwnProperty.call(animations, animationId)) {
                  var animation = animations[animationId];
                  var parameters = animation.parameters;
                  if (defined(parameters)) {
                      var samplers = animation.samplers;
                      for (var samplerId in samplers) {
                          if (Object.prototype.hasOwnProperty.call(samplers, samplerId)) {
                              var sampler = samplers[samplerId];
                              sampler.input = parameters[sampler.input];
                              sampler.output = parameters[sampler.output];
                          }
                      }
                      delete animation.parameters;
                  }
              }
          }
      }

      function objectToArray(object, mapping) {
          var array = [];
          for (var id in object) {
              if (Object.prototype.hasOwnProperty.call(object, id)) {
                  var value = object[id];
                  mapping[id] = array.length;
                  array.push(value);
                  if (!defined(value.name)) {
                      value.name = id;
                  }
              }
          }
          return array;
      }

      function objectsToArrays(gltf) {
          var i;
          var globalMapping = {
              accessors: {},
              animations: {},
              buffers: {},
              bufferViews: {},
              cameras: {},
              images: {},
              materials: {},
              meshes: {},
              nodes: {},
              programs: {},
              samplers: {},
              scenes: {},
              shaders: {},
              skins: {},
              textures: {},
              techniques: {}
          };

          // Map joint names to id names
          var jointName;
          var jointNameToId = {};
          var nodes = gltf.nodes;
          for (var id in nodes) {
              if (Object.prototype.hasOwnProperty.call(nodes, id)) {
                  jointName = nodes[id].jointName;
                  if (defined(jointName)) {
                      jointNameToId[jointName] = id;
                  }
              }
          }

          // Convert top level objects to arrays
          for (var topLevelId in gltf) {
              if (Object.prototype.hasOwnProperty.call(gltf, topLevelId) && defined(globalMapping[topLevelId])) {
                  var objectMapping = {};
                  var object = gltf[topLevelId];
                  gltf[topLevelId] = objectToArray(object, objectMapping);
                  globalMapping[topLevelId] = objectMapping;
              }
          }

          // Remap joint names to array indexes
          for (jointName in jointNameToId) {
              if (Object.prototype.hasOwnProperty.call(jointNameToId, jointName)) {
                  jointNameToId[jointName] = globalMapping.nodes[jointNameToId[jointName]];
              }
          }

          // Fix references
          if (defined(gltf.scene)) {
              gltf.scene = globalMapping.scenes[gltf.scene];
          }
          ForEach.bufferView(gltf, function(bufferView) {
              if (defined(bufferView.buffer)) {
                  bufferView.buffer = globalMapping.buffers[bufferView.buffer];
              }
          });
          ForEach.accessor(gltf, function(accessor) {
              if (defined(accessor.bufferView)) {
                  accessor.bufferView = globalMapping.bufferViews[accessor.bufferView];
              }
          });
          ForEach.shader(gltf, function(shader) {
              var extensions = shader.extensions;
              if (defined(extensions)) {
                  var binaryGltf = extensions.KHR_binary_glTF;
                  if (defined(binaryGltf)) {
                      shader.bufferView = globalMapping.bufferViews[binaryGltf.bufferView];
                      delete extensions.KHR_binary_glTF;
                  }
                  if (Object.keys(extensions).length === 0) {
                      delete shader.extensions;
                  }
              }
          });
          ForEach.program(gltf, function(program) {
              if (defined(program.vertexShader)) {
                  program.vertexShader = globalMapping.shaders[program.vertexShader];
              }
              if (defined(program.fragmentShader)) {
                  program.fragmentShader = globalMapping.shaders[program.fragmentShader];
              }
          });
          ForEach.technique(gltf, function(technique) {
              if (defined(technique.program)) {
                  technique.program = globalMapping.programs[technique.program];
              }
              ForEach.techniqueParameter(technique, function(parameter) {
                  if (defined(parameter.node)) {
                      parameter.node = globalMapping.nodes[parameter.node];
                  }
                  var value = parameter.value;
                  if (typeof value === 'string') {
                      parameter.value = {
                          index: globalMapping.textures[value]
                      };
                  }
              });
          });
          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  if (defined(primitive.indices)) {
                      primitive.indices = globalMapping.accessors[primitive.indices];
                  }
                  ForEach.meshPrimitiveAttribute(primitive, function(accessorId, semantic) {
                      primitive.attributes[semantic] = globalMapping.accessors[accessorId];
                  });
                  if (defined(primitive.material)) {
                      primitive.material = globalMapping.materials[primitive.material];
                  }
              });
          });
          ForEach.node(gltf, function(node) {
              var children = node.children;
              if (defined(children)) {
                  var childrenLength = children.length;
                  for (i = 0; i < childrenLength; ++i) {
                      children[i] = globalMapping.nodes[children[i]];
                  }
              }
              if (defined(node.meshes)) {
                  // Split out meshes on nodes
                  var meshes = node.meshes;
                  var meshesLength = meshes.length;
                  if (meshesLength > 0) {
                      node.mesh = globalMapping.meshes[meshes[0]];
                      for (i = 1; i < meshesLength; ++i) {
                          var meshNode = {
                              mesh: globalMapping.meshes[meshes[i]]
                          };
                          var meshNodeId = addToArray(gltf.nodes, meshNode);
                          if (!defined(children)) {
                              children = [];
                              node.children = children;
                          }
                          children.push(meshNodeId);
                      }
                  }
                  delete node.meshes;
              }
              if (defined(node.camera)) {
                  node.camera = globalMapping.cameras[node.camera];
              }
              if (defined(node.skin)) {
                  node.skin = globalMapping.skins[node.skin];
              }
              if (defined(node.skeletons)) {
                  // Assign skeletons to skins
                  var skeletons = node.skeletons;
                  var skeletonsLength = skeletons.length;
                  if ((skeletonsLength > 0) && defined(node.skin)) {
                      var skin = gltf.skins[node.skin];
                      skin.skeleton = globalMapping.nodes[skeletons[0]];
                  }
                  delete node.skeletons;
              }
              if (defined(node.jointName)) {
                  delete node.jointName;
              }
          });
          ForEach.skin(gltf, function(skin) {
              if (defined(skin.inverseBindMatrices)) {
                  skin.inverseBindMatrices = globalMapping.accessors[skin.inverseBindMatrices];
              }
              var jointNames = skin.jointNames;
              if (defined(jointNames)) {
                  var joints = [];
                  var jointNamesLength = jointNames.length;
                  for (i = 0; i < jointNamesLength; ++i) {
                      joints[i] = jointNameToId[jointNames[i]];
                  }
                  skin.joints = joints;
                  delete skin.jointNames;
              }
          });
          ForEach.scene(gltf, function(scene) {
              var sceneNodes = scene.nodes;
              if (defined(sceneNodes)) {
                  var sceneNodesLength = sceneNodes.length;
                  for (i = 0; i < sceneNodesLength; ++i) {
                      sceneNodes[i] = globalMapping.nodes[sceneNodes[i]];
                  }
              }
          });
          ForEach.animation(gltf, function(animation) {
              var samplerMapping = {};
              animation.samplers = objectToArray(animation.samplers, samplerMapping);
              ForEach.animationSampler(animation, function(sampler) {
                  sampler.input = globalMapping.accessors[sampler.input];
                  sampler.output = globalMapping.accessors[sampler.output];
              });
              ForEach.animationChannel(animation, function(channel) {
                  channel.sampler = samplerMapping[channel.sampler];
                  var target = channel.target;
                  if (defined(target)) {
                      target.node = globalMapping.nodes[target.id];
                      delete target.id;
                  }
              });
          });
          ForEach.material(gltf, function(material) {
              if (defined(material.technique)) {
                  material.technique = globalMapping.techniques[material.technique];
              }
              ForEach.materialValue(material, function(value, name) {
                  if (typeof value === 'string') {
                      material.values[name] = {
                          index: globalMapping.textures[value]
                      };
                  }
              });
              var extensions = material.extensions;
              if (defined(extensions)) {
                  var materialsCommon = extensions.KHR_materials_common;
                  if (defined(materialsCommon)) {
                      ForEach.materialValue(materialsCommon, function(value, name) {
                          if (typeof value === 'string') {
                              materialsCommon.values[name] = {
                                  index: globalMapping.textures[value]
                              };
                          }
                      });
                  }
              }
          });
          ForEach.image(gltf, function(image) {
              var extensions = image.extensions;
              if (defined(extensions)) {
                  var binaryGltf = extensions.KHR_binary_glTF;
                  if (defined(binaryGltf)) {
                      image.bufferView = globalMapping.bufferViews[binaryGltf.bufferView];
                      image.mimeType = binaryGltf.mimeType;
                      delete extensions.KHR_binary_glTF;
                  }
                  if (Object.keys(extensions).length === 0) {
                      delete image.extensions;
                  }
              }
              ForEach.compressedImage(image, function(compressedImage) {
                  var compressedExtensions = compressedImage.extensions;
                  if (defined(compressedExtensions)) {
                      var compressedBinaryGltf = compressedExtensions.KHR_binary_glTF;
                      if (defined(compressedBinaryGltf)) {
                          compressedImage.bufferView = globalMapping.bufferViews[compressedBinaryGltf.bufferView];
                          compressedImage.mimeType = compressedBinaryGltf.mimeType;
                          delete compressedExtensions.KHR_binary_glTF;
                      }
                      if (Object.keys(extensions).length === 0) {
                          delete compressedImage.extensions;
                      }
                  }
              });
          });
          ForEach.texture(gltf, function(texture) {
              if (defined(texture.sampler)) {
                  texture.sampler = globalMapping.samplers[texture.sampler];
              }
              if (defined(texture.source)) {
                  texture.source = globalMapping.images[texture.source];
              }
          });
      }

      function removeAnimationSamplerNames(gltf) {
          ForEach.animation(gltf, function(animation) {
              ForEach.animationSampler(animation, function(sampler) {
                  delete sampler.name;
              });
          });
      }

      function removeEmptyArrays(gltf) {
          for (var topLevelId in gltf) {
              if (Object.prototype.hasOwnProperty.call(gltf, topLevelId)) {
                  var array = gltf[topLevelId];
                  if (Array.isArray(array) && array.length === 0) {
                      delete gltf[topLevelId];
                  }
              }
          }
          ForEach.node(gltf, function(node) {
              if (defined(node.children) && node.children.length === 0) {
                  delete node.children;
              }
          });
      }

      function stripAsset(gltf) {
          var asset = gltf.asset;
          delete asset.profile;
          delete asset.premultipliedAlpha;
      }

      var knownExtensions = {
          CESIUM_RTC: true,
          KHR_materials_common: true,
          WEB3D_quantized_attributes: true
      };
      function requireKnownExtensions(gltf) {
          var extensionsUsed = gltf.extensionsUsed;
          gltf.extensionsRequired = defaultValue(gltf.extensionsRequired, []);
          if (defined(extensionsUsed)) {
              var extensionsUsedLength = extensionsUsed.length;
              for (var i = 0; i < extensionsUsedLength; ++i) {
                  var extension = extensionsUsed[i];
                  if (defined(knownExtensions[extension])) {
                      gltf.extensionsRequired.push(extension);
                  }
              }
          }
      }

      function removeBufferType(gltf) {
          ForEach.buffer(gltf, function(buffer) {
              delete buffer.type;
          });
      }

      function removeTextureProperties(gltf) {
          ForEach.texture(gltf, function(texture) {
              delete texture.format;
              delete texture.internalFormat;
              delete texture.target;
              delete texture.type;
          });
      }

      function requireAttributeSetIndex(gltf) {
          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  ForEach.meshPrimitiveAttribute(primitive, function(accessorId, semantic) {
                      if (semantic === 'TEXCOORD') {
                          primitive.attributes.TEXCOORD_0 = accessorId;
                      } else if (semantic === 'COLOR') {
                          primitive.attributes.COLOR_0 = accessorId;
                      }
                  });
                  delete primitive.attributes.TEXCOORD;
                  delete primitive.attributes.COLOR;
              });
          });
          ForEach.technique(gltf, function(technique) {
              ForEach.techniqueParameter(technique, function(parameter) {
                  var semantic = parameter.semantic;
                  if (defined(semantic)) {
                      if (semantic === 'TEXCOORD') {
                          parameter.semantic = 'TEXCOORD_0';
                      } else if (semantic === 'COLOR') {
                          parameter.semantic = 'COLOR_0';
                      }
                  }
              });
          });
      }

      var knownSemantics = {
          POSITION: true,
          NORMAL: true,
          TANGENT: true
      };
      var indexedSemantics = {
          COLOR: 'COLOR',
          JOINT : 'JOINTS',
          JOINTS: 'JOINTS',
          TEXCOORD: 'TEXCOORD',
          WEIGHT: 'WEIGHTS',
          WEIGHTS: 'WEIGHTS'
      };
      function underscoreApplicationSpecificSemantics(gltf) {
          var mappedSemantics = {};
          ForEach.mesh(gltf, function(mesh) {
              ForEach.meshPrimitive(mesh, function(primitive) {
                  /*eslint-disable no-unused-vars*/
                  ForEach.meshPrimitiveAttribute(primitive, function(accessorId, semantic) {
                      if (semantic.charAt(0) !== '_') {
                          var setIndex = semantic.search(/_[0-9]+/g);
                          var strippedSemantic = semantic;
                          var suffix = '_0';
                          if (setIndex >= 0) {
                              strippedSemantic = semantic.substring(0, setIndex);
                              suffix = semantic.substring(setIndex);
                          }
                          var newSemantic;
                          var indexedSemantic = indexedSemantics[strippedSemantic];
                          if (defined(indexedSemantic)) {
                              newSemantic = indexedSemantic + suffix;
                              mappedSemantics[semantic] = newSemantic;
                          } else if (!defined(knownSemantics[strippedSemantic])) {
                              newSemantic = '_' + semantic;
                              mappedSemantics[semantic] = newSemantic;
                          }
                      }
                  });
                  for (var semantic in mappedSemantics) {
                      if (Object.prototype.hasOwnProperty.call(mappedSemantics, semantic)) {
                          var mappedSemantic = mappedSemantics[semantic];
                          var accessorId = primitive.attributes[semantic];
                          if (defined(accessorId)) {
                              delete primitive.attributes[semantic];
                              primitive.attributes[mappedSemantic] = accessorId;
                          }
                      }
                  }
              });
          });
          ForEach.technique(gltf, function(technique) {
              ForEach.techniqueParameter(technique, function(parameter) {
                  var mappedSemantic = mappedSemantics[parameter.semantic];
                  if (defined(mappedSemantic)) {
                      parameter.semantic = mappedSemantic;
                  }
              });
          });
      }

      function clampCameraParameters(gltf) {
          ForEach.camera(gltf, function(camera) {
              var perspective = camera.perspective;
              if (defined(perspective)) {
                  var aspectRatio = perspective.aspectRatio;
                  if (defined(aspectRatio) && aspectRatio === 0.0) {
                      delete perspective.aspectRatio;
                  }
                  var yfov = perspective.yfov;
                  if (defined(yfov) && yfov === 0.0) {
                      perspective.yfov = 1.0;
                  }
              }
          });
      }

      function computeAccessorByteStride(gltf, accessor) {
          return (defined(accessor.byteStride) && accessor.byteStride !== 0) ? accessor.byteStride : getAccessorByteStride(gltf, accessor);
      }

      function requireByteLength(gltf) {
          ForEach.buffer(gltf, function(buffer) {
              if (!defined(buffer.byteLength)) {
                  buffer.byteLength = buffer.extras._pipeline.source.length;
              }
          });
          ForEach.accessor(gltf, function(accessor) {
              var bufferViewId = accessor.bufferView;
              if (defined(bufferViewId)) {
                  var bufferView = gltf.bufferViews[bufferViewId];
                  var accessorByteStride = computeAccessorByteStride(gltf, accessor);
                  var accessorByteEnd = accessor.byteOffset + accessor.count * accessorByteStride;
                  bufferView.byteLength = Math.max(defaultValue(bufferView.byteLength, 0), accessorByteEnd);
              }
          });
      }

      function moveByteStrideToBufferView(gltf) {
          var i;
          var j;
          var bufferView;
          var bufferViews = gltf.bufferViews;

          var bufferViewHasVertexAttributes = {};
          ForEach.accessorContainingVertexAttributeData(gltf, function(accessorId) {
              var accessor = gltf.accessors[accessorId];
              if (defined(accessor.bufferView)) {
                  bufferViewHasVertexAttributes[accessor.bufferView] = true;
              }
          });

          // Map buffer views to a list of accessors
          var bufferViewMap = {};
          ForEach.accessor(gltf, function(accessor) {
              if (defined(accessor.bufferView)) {
                  bufferViewMap[accessor.bufferView] = defaultValue(bufferViewMap[accessor.bufferView], []);
                  bufferViewMap[accessor.bufferView].push(accessor);
              }
          });

          // Split accessors with different byte strides
          for (var bufferViewId in bufferViewMap) {
              if (Object.prototype.hasOwnProperty.call(bufferViewMap, bufferViewId)) {
                  bufferView = bufferViews[bufferViewId];
                  var accessors = bufferViewMap[bufferViewId];
                  accessors.sort(function(a, b) {
                      return a.byteOffset - b.byteOffset;
                  });
                  var currentByteOffset = 0;
                  var currentIndex = 0;
                  var accessorsLength = accessors.length;
                  for (i = 0; i < accessorsLength; ++i) {
                      var accessor = accessors[i];
                      var accessorByteStride = computeAccessorByteStride(gltf, accessor);
                      var accessorByteOffset = accessor.byteOffset;
                      var accessorByteLength = accessor.count * accessorByteStride;
                      delete accessor.byteStride;

                      var hasNextAccessor = (i < accessorsLength - 1);
                      var nextAccessorByteStride = hasNextAccessor ? computeAccessorByteStride(gltf, accessors[i + 1]) : undefined;
                      if (accessorByteStride !== nextAccessorByteStride) {
                          var newBufferView = clone(bufferView, true);
                          if (bufferViewHasVertexAttributes[bufferViewId]) {
                              newBufferView.byteStride = accessorByteStride;
                          }
                          newBufferView.byteOffset += currentByteOffset;
                          newBufferView.byteLength = accessorByteOffset + accessorByteLength - currentByteOffset;
                          var newBufferViewId = addToArray(bufferViews, newBufferView);
                          for (j = currentIndex; j <= i; ++j) {
                              accessor = accessors[j];
                              accessor.bufferView = newBufferViewId;
                              accessor.byteOffset = accessor.byteOffset - currentByteOffset;
                          }
                          // Set current byte offset to next accessor's byte offset
                          currentByteOffset = hasNextAccessor ? accessors[i + 1].byteOffset : undefined;
                          currentIndex = i + 1;
                      }
                  }
              }
          }

          // Remove unused buffer views
          removeUnusedElements(gltf, ['accessor', 'bufferView', 'buffer']);
      }

      function requirePositionAccessorMinMax(gltf) {
          ForEach.accessorWithSemantic(gltf, 'POSITION', function(accessorId) {
              var accessor = gltf.accessors[accessorId];
              if (!defined(accessor.min) || !defined(accessor.max)) {
                  var minMax = findAccessorMinMax(gltf, accessor);
                  accessor.min = minMax.min;
                  accessor.max = minMax.max;
              }
          });
      }

      function isNodeEmpty(node) {
          return (!defined(node.children) || node.children.length === 0) &&
              (!defined(node.meshes) || node.meshes.length === 0) &&
              !defined(node.camera) && !defined(node.skin) && !defined(node.skeletons) && !defined(node.jointName) &&
              (!defined(node.translation) || Cartesian3.fromArray(node.translation).equals(Cartesian3.ZERO)) &&
              (!defined(node.scale) || Cartesian3.fromArray(node.scale).equals(new Cartesian3(1.0, 1.0, 1.0))) &&
              (!defined(node.rotation) || Cartesian4.fromArray(node.rotation).equals(new Cartesian4(0.0, 0.0, 0.0, 1.0))) &&
              (!defined(node.matrix) || Matrix4.fromColumnMajorArray(node.matrix).equals(Matrix4.IDENTITY)) &&
              !defined(node.extensions) && !defined(node.extras);
      }

      function deleteNode(gltf, nodeId) {
          // Remove from list of nodes in scene
          ForEach.scene(gltf, function(scene) {
              var sceneNodes = scene.nodes;
              if (defined(sceneNodes)) {
                  var sceneNodesLength = sceneNodes.length;
                  for (var i = sceneNodesLength; i >= 0; --i) {
                      if (sceneNodes[i] === nodeId) {
                          sceneNodes.splice(i, 1);
                          return;
                      }
                  }
              }
          });

          // Remove parent node's reference to this node, and delete the parent if also empty
          ForEach.node(gltf, function(parentNode, parentNodeId) {
              if (defined(parentNode.children)) {
                  var index = parentNode.children.indexOf(nodeId);
                  if (index > -1) {
                      parentNode.children.splice(index, 1);

                      if (isNodeEmpty(parentNode)) {
                          deleteNode(gltf, parentNodeId);
                      }
                  }
              }
          });

          delete gltf.nodes[nodeId];
      }

      function removeEmptyNodes(gltf) {
          ForEach.node(gltf, function(node, nodeId) {
              if (isNodeEmpty(node)) {
                  deleteNode(gltf, nodeId);
              }
          });

          return gltf;
      }

      function requireAnimationAccessorMinMax(gltf) {
          ForEach.animation(gltf, function(animation) {
              ForEach.animationSampler(animation, function(sampler) {
                  var accessor = gltf.accessors[sampler.input];
                  if (!defined(accessor.min) || !defined(accessor.max)) {
                      var minMax = findAccessorMinMax(gltf, accessor);
                      accessor.min = minMax.min;
                      accessor.max = minMax.max;
                  }
              });
          });
      }

      function glTF10to20(gltf) {
          gltf.asset = defaultValue(gltf.asset, {});
          gltf.asset.version = '2.0';
          // material.instanceTechnique properties should be directly on the material. instanceTechnique is a gltf 0.8 property but is seen in some 1.0 models.
          updateInstanceTechniques(gltf);
          // animation.samplers now refers directly to accessors and animation.parameters should be removed
          removeAnimationSamplersIndirection(gltf);
          // Remove empty nodes and re-assign referencing indices
          removeEmptyNodes(gltf);
          // Top-level objects are now arrays referenced by index instead of id
          objectsToArrays(gltf);
          // Animation.sampler objects cannot have names
          removeAnimationSamplerNames(gltf);
          // asset.profile no longer exists
          stripAsset(gltf);
          // Move known extensions from extensionsUsed to extensionsRequired
          requireKnownExtensions(gltf);
          // bufferView.byteLength and buffer.byteLength are required
          requireByteLength(gltf);
          // byteStride moved from accessor to bufferView
          moveByteStrideToBufferView(gltf);
          // accessor.min and accessor.max must be defined for accessors containing POSITION attributes
          requirePositionAccessorMinMax(gltf);
          // An animation sampler's input accessor must have min and max properties defined
          requireAnimationAccessorMinMax(gltf);
          // buffer.type is unnecessary and should be removed
          removeBufferType(gltf);
          // Remove format, internalFormat, target, and type
          removeTextureProperties(gltf);
          // TEXCOORD and COLOR attributes must be written with a set index (TEXCOORD_#)
          requireAttributeSetIndex(gltf);
          // Add underscores to application-specific parameters
          underscoreApplicationSpecificSemantics(gltf);
          // Accessors referenced by JOINTS_0 and WEIGHTS_0 attributes must have correct component types
          updateAccessorComponentTypes(gltf);
          // Clamp camera parameters
          clampCameraParameters(gltf);
          // Move legacy technique render states to material properties and add KHR_blend extension blending functions
          moveTechniqueRenderStates(gltf);
          // Add material techniques to KHR_techniques_webgl extension, removing shaders, programs, and techniques
          moveTechniquesToExtension(gltf);
          // Remove empty arrays
          removeEmptyArrays(gltf);
      }

  /**
   * @private
   */
  function ModelLoadResources() {
    this.initialized = false;
    this.resourcesParsed = false;

    this.vertexBuffersToCreate = new Queue();
    this.indexBuffersToCreate = new Queue();
    this.buffers = {};
    this.pendingBufferLoads = 0;

    this.programsToCreate = new Queue();
    this.shaders = {};
    this.pendingShaderLoads = 0;

    this.texturesToCreate = new Queue();
    this.pendingTextureLoads = 0;

    this.texturesToCreateFromBufferView = new Queue();
    this.pendingBufferViewToImage = 0;

    this.createSamplers = true;
    this.createSkins = true;
    this.createRuntimeAnimations = true;
    this.createVertexArrays = true;
    this.createRenderStates = true;
    this.createUniformMaps = true;
    this.createRuntimeNodes = true;

    this.createdBufferViews = {};
    this.primitivesToDecode = new Queue();
    this.activeDecodingTasks = 0;
    this.pendingDecodingCache = false;

    this.skinnedNodesIds = [];
  }

  /**
   * This function differs from the normal subarray function
   * because it takes offset and length, rather than begin and end.
   * @private
   */
  function getSubarray(array, offset, length) {
    return array.subarray(offset, offset + length);
  }

  ModelLoadResources.prototype.getBuffer = function (bufferView) {
    return getSubarray(
      this.buffers[bufferView.buffer],
      bufferView.byteOffset,
      bufferView.byteLength
    );
  };

  ModelLoadResources.prototype.finishedPendingBufferLoads = function () {
    return this.pendingBufferLoads === 0;
  };

  ModelLoadResources.prototype.finishedBuffersCreation = function () {
    return (
      this.pendingBufferLoads === 0 &&
      this.vertexBuffersToCreate.length === 0 &&
      this.indexBuffersToCreate.length === 0
    );
  };

  ModelLoadResources.prototype.finishedProgramCreation = function () {
    return this.pendingShaderLoads === 0 && this.programsToCreate.length === 0;
  };

  ModelLoadResources.prototype.finishedTextureCreation = function () {
    var finishedPendingLoads = this.pendingTextureLoads === 0;
    var finishedResourceCreation =
      this.texturesToCreate.length === 0 &&
      this.texturesToCreateFromBufferView.length === 0;

    return finishedPendingLoads && finishedResourceCreation;
  };

  ModelLoadResources.prototype.finishedEverythingButTextureCreation = function () {
    var finishedPendingLoads =
      this.pendingBufferLoads === 0 && this.pendingShaderLoads === 0;
    var finishedResourceCreation =
      this.vertexBuffersToCreate.length === 0 &&
      this.indexBuffersToCreate.length === 0 &&
      this.programsToCreate.length === 0 &&
      this.pendingBufferViewToImage === 0;

    return (
      this.finishedDecoding() && finishedPendingLoads && finishedResourceCreation
    );
  };

  ModelLoadResources.prototype.finishedDecoding = function () {
    return (
      this.primitivesToDecode.length === 0 &&
      this.activeDecodingTasks === 0 &&
      !this.pendingDecodingCache
    );
  };

  ModelLoadResources.prototype.finished = function () {
    return (
      this.finishedDecoding() &&
      this.finishedTextureCreation() &&
      this.finishedEverythingButTextureCreation()
    );
  };

  /**
   * @private
   */
  var ModelUtility = {};

  /**
   * Updates the model's forward axis if the model is not a 2.0 model.
   *
   * @param {Object} model The model to update.
   */
  ModelUtility.updateForwardAxis = function (model) {
    var cachedSourceVersion = model.gltf.extras.sourceVersion;

    if (
      (defined(cachedSourceVersion) && cachedSourceVersion !== "2.0") ||
      ModelUtility.getAssetVersion(model.gltf) !== "2.0"
    ) {
      model._gltfForwardAxis = Axis$1.X;
    }
  };

  /**
   *  Gets the string representing the glTF asset version.
   *
   *  @param {Object} gltf A javascript object containing a glTF asset.
   *  @returns {String} The glTF asset version string.
   */
  ModelUtility.getAssetVersion = function (gltf) {
    // In glTF 1.0 it was valid to omit the version number.
    if (!defined(gltf.asset) || !defined(gltf.asset.version)) {
      return "1.0";
    }

    return gltf.asset.version;
  };

  /**
   * Splits primitive materials with values incompatible for generating techniques.
   *
   * @param {Object} gltf A javascript object containing a glTF asset.
   * @returns {Object} The glTF asset with modified materials.
   */
  ModelUtility.splitIncompatibleMaterials = function (gltf) {
    var accessors = gltf.accessors;
    var materials = gltf.materials;
    var primitiveInfoByMaterial = {};
    ForEach.mesh(gltf, function (mesh) {
      ForEach.meshPrimitive(mesh, function (primitive) {
        var materialIndex = primitive.material;
        var material = materials[materialIndex];

        var jointAccessorId = primitive.attributes.JOINTS_0;
        var componentType;
        var accessorType;
        if (defined(jointAccessorId)) {
          var jointAccessor = accessors[jointAccessorId];
          componentType = jointAccessor.componentType;
          accessorType = jointAccessor.type;
        }
        var isSkinned = defined(jointAccessorId) && accessorType === "VEC4";
        var hasVertexColors = defined(primitive.attributes.COLOR_0);
        var hasMorphTargets = defined(primitive.targets);
        var hasNormals = defined(primitive.attributes.NORMAL);
        var hasTangents = defined(primitive.attributes.TANGENT);
        var hasTexCoords = defined(primitive.attributes.TEXCOORD_0);
        var hasTexCoord1 =
          hasTexCoords && defined(primitive.attributes.TEXCOORD_1);
        var hasOutline =
          defined(primitive.extensions) &&
          defined(primitive.extensions.CESIUM_primitive_outline);

        var primitiveInfo = primitiveInfoByMaterial[materialIndex];
        if (!defined(primitiveInfo)) {
          primitiveInfoByMaterial[materialIndex] = {
            skinning: {
              skinned: isSkinned,
              componentType: componentType,
            },
            hasVertexColors: hasVertexColors,
            hasMorphTargets: hasMorphTargets,
            hasNormals: hasNormals,
            hasTangents: hasTangents,
            hasTexCoords: hasTexCoords,
            hasTexCoord1: hasTexCoord1,
            hasOutline: hasOutline,
          };
        } else if (
          primitiveInfo.skinning.skinned !== isSkinned ||
          primitiveInfo.hasVertexColors !== hasVertexColors ||
          primitiveInfo.hasMorphTargets !== hasMorphTargets ||
          primitiveInfo.hasNormals !== hasNormals ||
          primitiveInfo.hasTangents !== hasTangents ||
          primitiveInfo.hasTexCoords !== hasTexCoords ||
          primitiveInfo.hasTexCoord1 !== hasTexCoord1 ||
          primitiveInfo.hasOutline !== hasOutline
        ) {
          // This primitive uses the same material as another one that either:
          // * Isn't skinned
          // * Uses a different type to store joints and weights
          // * Doesn't have vertex colors, morph targets, normals, tangents, or texCoords
          // * Doesn't have a CESIUM_primitive_outline extension.
          var clonedMaterial = clone(material, true);
          // Split this off as a separate material
          materialIndex = addToArray(materials, clonedMaterial);
          primitive.material = materialIndex;
          primitiveInfoByMaterial[materialIndex] = {
            skinning: {
              skinned: isSkinned,
              componentType: componentType,
            },
            hasVertexColors: hasVertexColors,
            hasMorphTargets: hasMorphTargets,
            hasNormals: hasNormals,
            hasTangents: hasTangents,
            hasTexCoords: hasTexCoords,
            hasTexCoord1: hasTexCoord1,
            hasOutline: hasOutline,
          };
        }
      });
    });

    return primitiveInfoByMaterial;
  };

  ModelUtility.getShaderVariable = function (type) {
    if (type === "SCALAR") {
      return "float";
    }
    return type.toLowerCase();
  };

  ModelUtility.ModelState = {
    NEEDS_LOAD: 0,
    LOADING: 1,
    LOADED: 2, // Renderable, but textures can still be pending when incrementallyLoadTextures is true.
    FAILED: 3,
  };

  ModelUtility.getFailedLoadFunction = function (model, type, path) {
    return function (error) {
      model._state = ModelUtility.ModelState.FAILED;
      var message = "Failed to load " + type + ": " + path;
      if (defined(error)) {
        message += "\n" + error.message;
      }
      model._readyPromise.reject(new RuntimeError(message));
    };
  };

  ModelUtility.parseBuffers = function (model, bufferLoad) {
    var loadResources = model._loadResources;
    ForEach.buffer(model.gltf, function (buffer, bufferViewId) {
      if (defined(buffer.extras._pipeline.source)) {
        loadResources.buffers[bufferViewId] = buffer.extras._pipeline.source;
      } else if (defined(bufferLoad)) {
        var bufferResource = model._resource.getDerivedResource({
          url: buffer.uri,
        });
        ++loadResources.pendingBufferLoads;
        bufferResource
          .fetchArrayBuffer()
          .then(bufferLoad(model, bufferViewId))
          .otherwise(
            ModelUtility.getFailedLoadFunction(
              model,
              "buffer",
              bufferResource.url
            )
          );
      }
    });
  };

  var aMinScratch = new Cartesian3();
  var aMaxScratch = new Cartesian3();

  ModelUtility.computeBoundingSphere = function (model) {
    var gltf = model.gltf;
    var gltfNodes = gltf.nodes;
    var gltfMeshes = gltf.meshes;
    var rootNodes = gltf.scenes[gltf.scene].nodes;
    var rootNodesLength = rootNodes.length;

    var nodeStack = [];

    var min = new Cartesian3(
      Number.MAX_VALUE,
      Number.MAX_VALUE,
      Number.MAX_VALUE
    );
    var max = new Cartesian3(
      -Number.MAX_VALUE,
      -Number.MAX_VALUE,
      -Number.MAX_VALUE
    );

    for (var i = 0; i < rootNodesLength; ++i) {
      var n = gltfNodes[rootNodes[i]];
      n._transformToRoot = ModelUtility.getTransform(n);
      nodeStack.push(n);

      while (nodeStack.length > 0) {
        n = nodeStack.pop();
        var transformToRoot = n._transformToRoot;

        var meshId = n.mesh;
        if (defined(meshId)) {
          var mesh = gltfMeshes[meshId];
          var primitives = mesh.primitives;
          var primitivesLength = primitives.length;
          for (var m = 0; m < primitivesLength; ++m) {
            var positionAccessor = primitives[m].attributes.POSITION;
            if (defined(positionAccessor)) {
              var minMax = ModelUtility.getAccessorMinMax(gltf, positionAccessor);
              if (defined(minMax.min) && defined(minMax.max)) {
                var aMin = Cartesian3.fromArray(minMax.min, 0, aMinScratch);
                var aMax = Cartesian3.fromArray(minMax.max, 0, aMaxScratch);

                Matrix4.multiplyByPoint(transformToRoot, aMin, aMin);
                Matrix4.multiplyByPoint(transformToRoot, aMax, aMax);
                Cartesian3.minimumByComponent(min, aMin, min);
                Cartesian3.maximumByComponent(max, aMax, max);
              }
            }
          }
        }

        var children = n.children;
        if (defined(children)) {
          var childrenLength = children.length;
          for (var k = 0; k < childrenLength; ++k) {
            var child = gltfNodes[children[k]];
            child._transformToRoot = ModelUtility.getTransform(child);
            Matrix4.multiplyTransformation(
              transformToRoot,
              child._transformToRoot,
              child._transformToRoot
            );
            nodeStack.push(child);
          }
        }
        delete n._transformToRoot;
      }
    }

    var boundingSphere = BoundingSphere.fromCornerPoints(min, max);
    if (model._forwardAxis === Axis$1.Z) {
      // glTF 2.0 has a Z-forward convention that must be adapted here to X-forward.
      BoundingSphere.transformWithoutScale(
        boundingSphere,
        Axis$1.Z_UP_TO_X_UP,
        boundingSphere
      );
    }
    if (model._upAxis === Axis$1.Y) {
      BoundingSphere.transformWithoutScale(
        boundingSphere,
        Axis$1.Y_UP_TO_Z_UP,
        boundingSphere
      );
    } else if (model._upAxis === Axis$1.X) {
      BoundingSphere.transformWithoutScale(
        boundingSphere,
        Axis$1.X_UP_TO_Z_UP,
        boundingSphere
      );
    }
    return boundingSphere;
  };

  function techniqueAttributeForSemantic(technique, semantic) {
    return ForEach.techniqueAttribute(technique, function (
      attribute,
      attributeName
    ) {
      if (attribute.semantic === semantic) {
        return attributeName;
      }
    });
  }

  function ensureSemanticExistenceForPrimitive(gltf, primitive) {
    var accessors = gltf.accessors;
    var materials = gltf.materials;
    var techniquesWebgl = gltf.extensions.KHR_techniques_webgl;

    var techniques = techniquesWebgl.techniques;
    var programs = techniquesWebgl.programs;
    var shaders = techniquesWebgl.shaders;
    var targets = primitive.targets;

    var attributes = primitive.attributes;
    for (var target in targets) {
      if (targets.hasOwnProperty(target)) {
        var targetAttributes = targets[target];
        for (var attribute in targetAttributes) {
          if (attribute !== "extras") {
            attributes[attribute + "_" + target] = targetAttributes[attribute];
          }
        }
      }
    }

    var material = materials[primitive.material];
    var technique =
      techniques[material.extensions.KHR_techniques_webgl.technique];
    var program = programs[technique.program];
    var vertexShader = shaders[program.vertexShader];

    for (var semantic in attributes) {
      if (attributes.hasOwnProperty(semantic)) {
        if (!defined(techniqueAttributeForSemantic(technique, semantic))) {
          var accessorId = attributes[semantic];
          var accessor = accessors[accessorId];
          var lowerCase = semantic.toLowerCase();
          if (lowerCase.charAt(0) === "_") {
            lowerCase = lowerCase.slice(1);
          }
          var attributeName = "a_" + lowerCase;
          technique.attributes[attributeName] = {
            semantic: semantic,
            type: accessor.componentType,
          };
          var pipelineExtras = vertexShader.extras._pipeline;
          var shaderText = pipelineExtras.source;
          shaderText =
            "attribute " +
            ModelUtility.getShaderVariable(accessor.type) +
            " " +
            attributeName +
            ";\n" +
            shaderText;
          pipelineExtras.source = shaderText;
        }
      }
    }
  }

  /**
   * Ensures all attributes present on the primitive are present in the technique and
   * vertex shader.
   *
   * @param {Object} gltf A javascript object containing a glTF asset.
   * @returns {Object} The glTF asset, including any additional attributes.
   */
  ModelUtility.ensureSemanticExistence = function (gltf) {
    ForEach.mesh(gltf, function (mesh) {
      ForEach.meshPrimitive(mesh, function (primitive) {
        ensureSemanticExistenceForPrimitive(gltf, primitive);
      });
    });

    return gltf;
  };

  /**
   * Creates attribute location for all attributes required by a technique.
   *
   * @param {Object} technique A glTF KHR_techniques_webgl technique object.
   * @param {Object} precreatedAttributes A dictionary object of pre-created attributes for which to also create locations.
   * @returns {Object} A dictionary object containing attribute names and their locations.
   */
  ModelUtility.createAttributeLocations = function (
    technique,
    precreatedAttributes
  ) {
    var attributeLocations = {};
    var hasIndex0 = false;
    var i = 1;

    ForEach.techniqueAttribute(technique, function (attribute, attributeName) {
      // Set the position attribute to the 0th index. In some WebGL implementations the shader
      // will not work correctly if the 0th attribute is not active. For example, some glTF models
      // list the normal attribute first but derived shaders like the cast-shadows shader do not use
      // the normal attribute.
      if (/pos/i.test(attributeName) && !hasIndex0) {
        attributeLocations[attributeName] = 0;
        hasIndex0 = true;
      } else {
        attributeLocations[attributeName] = i++;
      }
    });

    if (defined(precreatedAttributes)) {
      for (var attributeName in precreatedAttributes) {
        if (precreatedAttributes.hasOwnProperty(attributeName)) {
          attributeLocations[attributeName] = i++;
        }
      }
    }

    return attributeLocations;
  };

  ModelUtility.getAccessorMinMax = function (gltf, accessorId) {
    var accessor = gltf.accessors[accessorId];
    var extensions = accessor.extensions;
    var accessorMin = accessor.min;
    var accessorMax = accessor.max;
    // If this accessor is quantized, we should use the decoded min and max
    if (defined(extensions)) {
      var quantizedAttributes = extensions.WEB3D_quantized_attributes;
      if (defined(quantizedAttributes)) {
        accessorMin = quantizedAttributes.decodedMin;
        accessorMax = quantizedAttributes.decodedMax;
      }
    }
    return {
      min: accessorMin,
      max: accessorMax,
    };
  };

  function getTechniqueAttributeOrUniformFunction(
    gltf,
    technique,
    semantic,
    ignoreNodes
  ) {
    if (hasExtension(gltf, "KHR_techniques_webgl")) {
      return function (attributeOrUniform, attributeOrUniformName) {
        if (
          attributeOrUniform.semantic === semantic &&
          (!ignoreNodes || !defined(attributeOrUniform.node))
        ) {
          return attributeOrUniformName;
        }
      };
    }

    return function (parameterName, attributeOrUniformName) {
      var attributeOrUniform = technique.parameters[parameterName];
      if (
        attributeOrUniform.semantic === semantic &&
        (!ignoreNodes || !defined(attributeOrUniform.node))
      ) {
        return attributeOrUniformName;
      }
    };
  }

  ModelUtility.getAttributeOrUniformBySemantic = function (
    gltf,
    semantic,
    programId,
    ignoreNodes
  ) {
    return ForEach.technique(gltf, function (technique) {
      if (defined(programId) && technique.program !== programId) {
        return;
      }

      var value = ForEach.techniqueAttribute(
        technique,
        getTechniqueAttributeOrUniformFunction(
          gltf,
          technique,
          semantic,
          ignoreNodes
        )
      );

      if (defined(value)) {
        return value;
      }

      return ForEach.techniqueUniform(
        technique,
        getTechniqueAttributeOrUniformFunction(
          gltf,
          technique,
          semantic,
          ignoreNodes
        )
      );
    });
  };

  ModelUtility.getDiffuseAttributeOrUniform = function (gltf, programId) {
    var diffuseUniformName = ModelUtility.getAttributeOrUniformBySemantic(
      gltf,
      "COLOR_0",
      programId
    );
    if (!defined(diffuseUniformName)) {
      diffuseUniformName = ModelUtility.getAttributeOrUniformBySemantic(
        gltf,
        "_3DTILESDIFFUSE",
        programId
      );
    }
    return diffuseUniformName;
  };

  var nodeTranslationScratch = new Cartesian3();
  var nodeQuaternionScratch = new Quaternion();
  var nodeScaleScratch = new Cartesian3();

  ModelUtility.getTransform = function (node, result) {
    if (defined(node.matrix)) {
      return Matrix4.fromColumnMajorArray(node.matrix, result);
    }

    return Matrix4.fromTranslationQuaternionRotationScale(
      Cartesian3.fromArray(node.translation, 0, nodeTranslationScratch),
      Quaternion.unpack(node.rotation, 0, nodeQuaternionScratch),
      Cartesian3.fromArray(node.scale, 0, nodeScaleScratch),
      result
    );
  };

  ModelUtility.getUsedExtensions = function (gltf) {
    var extensionsUsed = gltf.extensionsUsed;
    var cachedExtensionsUsed = {};

    if (defined(extensionsUsed)) {
      var extensionsUsedLength = extensionsUsed.length;
      for (var i = 0; i < extensionsUsedLength; i++) {
        var extension = extensionsUsed[i];
        cachedExtensionsUsed[extension] = true;
      }
    }
    return cachedExtensionsUsed;
  };

  ModelUtility.getRequiredExtensions = function (gltf) {
    var extensionsRequired = gltf.extensionsRequired;
    var cachedExtensionsRequired = {};

    if (defined(extensionsRequired)) {
      var extensionsRequiredLength = extensionsRequired.length;
      for (var i = 0; i < extensionsRequiredLength; i++) {
        var extension = extensionsRequired[i];
        cachedExtensionsRequired[extension] = true;
      }
    }

    return cachedExtensionsRequired;
  };

  ModelUtility.supportedExtensions = {
    AGI_articulations: true,
    CESIUM_RTC: true,
    EXT_texture_webp: true,
    KHR_blend: true,
    KHR_binary_glTF: true,
    KHR_draco_mesh_compression: true,
    KHR_materials_common: true,
    KHR_techniques_webgl: true,
    KHR_materials_unlit: true,
    KHR_materials_pbrSpecularGlossiness: true,
    KHR_texture_transform: true,
    WEB3D_quantized_attributes: true,
  };

  ModelUtility.checkSupportedExtensions = function (
    extensionsRequired,
    browserSupportsWebp
  ) {
    for (var extension in extensionsRequired) {
      if (extensionsRequired.hasOwnProperty(extension)) {
        if (!ModelUtility.supportedExtensions[extension]) {
          throw new RuntimeError("Unsupported glTF Extension: " + extension);
        }

        if (extension === "EXT_texture_webp" && browserSupportsWebp === false) {
          throw new RuntimeError(
            "Loaded model requires WebP but browser does not support it."
          );
        }
      }
    }
  };

  ModelUtility.checkSupportedGlExtensions = function (extensionsUsed, context) {
    if (defined(extensionsUsed)) {
      var glExtensionsUsedLength = extensionsUsed.length;
      for (var i = 0; i < glExtensionsUsedLength; i++) {
        var extension = extensionsUsed[i];
        if (extension !== "OES_element_index_uint") {
          throw new RuntimeError("Unsupported WebGL Extension: " + extension);
        } else if (!context.elementIndexUint) {
          throw new RuntimeError(
            "OES_element_index_uint WebGL extension is not enabled."
          );
        }
      }
    }
  };

  function replaceAllButFirstInString(string, find, replace) {
    // Limit search to strings that are not a subset of other tokens.
    find += "(?!\\w)";
    find = new RegExp(find, "g");

    var index = string.search(find);
    return string.replace(find, function (match, offset) {
      return index === offset ? match : replace;
    });
  }

  function getQuantizedAttributes(gltf, accessorId) {
    var accessor = gltf.accessors[accessorId];
    var extensions = accessor.extensions;
    if (defined(extensions)) {
      return extensions.WEB3D_quantized_attributes;
    }
    return undefined;
  }

  function getAttributeVariableName(gltf, primitive, attributeSemantic) {
    var materialId = primitive.material;
    var material = gltf.materials[materialId];

    if (
      !hasExtension(gltf, "KHR_techniques_webgl") ||
      !defined(material.extensions) ||
      !defined(material.extensions.KHR_techniques_webgl)
    ) {
      return;
    }

    var techniqueId = material.extensions.KHR_techniques_webgl.technique;
    var techniquesWebgl = gltf.extensions.KHR_techniques_webgl;
    var technique = techniquesWebgl.techniques[techniqueId];
    return ForEach.techniqueAttribute(technique, function (
      attribute,
      attributeName
    ) {
      var semantic = attribute.semantic;
      if (semantic === attributeSemantic) {
        return attributeName;
      }
    });
  }

  ModelUtility.modifyShaderForDracoQuantizedAttributes = function (
    gltf,
    primitive,
    shader,
    decodedAttributes
  ) {
    var quantizedUniforms = {};
    for (var attributeSemantic in decodedAttributes) {
      if (decodedAttributes.hasOwnProperty(attributeSemantic)) {
        var attribute = decodedAttributes[attributeSemantic];
        var quantization = attribute.quantization;
        if (!defined(quantization)) {
          continue;
        }

        var attributeVarName = getAttributeVariableName(
          gltf,
          primitive,
          attributeSemantic
        );

        if (attributeSemantic.charAt(0) === "_") {
          attributeSemantic = attributeSemantic.substring(1);
        }
        var decodeUniformVarName =
          "gltf_u_dec_" + attributeSemantic.toLowerCase();

        if (!defined(quantizedUniforms[decodeUniformVarName])) {
          var newMain = "gltf_decoded_" + attributeSemantic;
          var decodedAttributeVarName = attributeVarName.replace(
            "a_",
            "gltf_a_dec_"
          );
          var size = attribute.componentsPerAttribute;

          // replace usages of the original attribute with the decoded version, but not the declaration
          shader = replaceAllButFirstInString(
            shader,
            attributeVarName,
            decodedAttributeVarName
          );

          // declare decoded attribute
          var variableType;
          if (quantization.octEncoded) {
            variableType = "vec3";
          } else if (size > 1) {
            variableType = "vec" + size;
          } else {
            variableType = "float";
          }
          shader = variableType + " " + decodedAttributeVarName + ";\n" + shader;

          // The gltf 2.0 COLOR_0 vertex attribute can be VEC4 or VEC3
          var vec3Color = size === 3 && attributeSemantic === "COLOR_0";
          if (vec3Color) {
            shader = replaceAllButFirstInString(
              shader,
              decodedAttributeVarName,
              "vec4(" + decodedAttributeVarName + ", 1.0)"
            );
          }

          // splice decode function into the shader
          var decode = "";
          if (quantization.octEncoded) {
            var decodeUniformVarNameRangeConstant =
              decodeUniformVarName + "_rangeConstant";
            shader =
              "uniform float " +
              decodeUniformVarNameRangeConstant +
              ";\n" +
              shader;
            decode =
              "\n" +
              "void main() {\n" +
              // Draco oct-encoding decodes to zxy order
              "    " +
              decodedAttributeVarName +
              " = czm_octDecode(" +
              attributeVarName +
              ".xy, " +
              decodeUniformVarNameRangeConstant +
              ").zxy;\n" +
              "    " +
              newMain +
              "();\n" +
              "}\n";
          } else {
            var decodeUniformVarNameNormConstant =
              decodeUniformVarName + "_normConstant";
            var decodeUniformVarNameMin = decodeUniformVarName + "_min";
            shader =
              "uniform float " +
              decodeUniformVarNameNormConstant +
              ";\n" +
              "uniform " +
              variableType +
              " " +
              decodeUniformVarNameMin +
              ";\n" +
              shader;
            var attributeVarAccess = vec3Color ? ".xyz" : "";
            decode =
              "\n" +
              "void main() {\n" +
              "    " +
              decodedAttributeVarName +
              " = " +
              decodeUniformVarNameMin +
              " + " +
              attributeVarName +
              attributeVarAccess +
              " * " +
              decodeUniformVarNameNormConstant +
              ";\n" +
              "    " +
              newMain +
              "();\n" +
              "}\n";
          }

          shader = ShaderSource.replaceMain(shader, newMain);
          shader += decode;
        }
      }
    }
    return {
      shader: shader,
    };
  };

  ModelUtility.modifyShaderForQuantizedAttributes = function (
    gltf,
    primitive,
    shader
  ) {
    var quantizedUniforms = {};
    var attributes = primitive.attributes;
    for (var attributeSemantic in attributes) {
      if (attributes.hasOwnProperty(attributeSemantic)) {
        var attributeVarName = getAttributeVariableName(
          gltf,
          primitive,
          attributeSemantic
        );
        var accessorId = primitive.attributes[attributeSemantic];

        if (attributeSemantic.charAt(0) === "_") {
          attributeSemantic = attributeSemantic.substring(1);
        }
        var decodeUniformVarName =
          "gltf_u_dec_" + attributeSemantic.toLowerCase();

        var decodeUniformVarNameScale = decodeUniformVarName + "_scale";
        var decodeUniformVarNameTranslate = decodeUniformVarName + "_translate";
        if (
          !defined(quantizedUniforms[decodeUniformVarName]) &&
          !defined(quantizedUniforms[decodeUniformVarNameScale])
        ) {
          var quantizedAttributes = getQuantizedAttributes(gltf, accessorId);
          if (defined(quantizedAttributes)) {
            var decodeMatrix = quantizedAttributes.decodeMatrix;
            var newMain = "gltf_decoded_" + attributeSemantic;
            var decodedAttributeVarName = attributeVarName.replace(
              "a_",
              "gltf_a_dec_"
            );
            var size = Math.floor(Math.sqrt(decodeMatrix.length));

            // replace usages of the original attribute with the decoded version, but not the declaration
            shader = replaceAllButFirstInString(
              shader,
              attributeVarName,
              decodedAttributeVarName
            );
            // declare decoded attribute
            var variableType;
            if (size > 2) {
              variableType = "vec" + (size - 1);
            } else {
              variableType = "float";
            }
            shader =
              variableType + " " + decodedAttributeVarName + ";\n" + shader;
            // splice decode function into the shader - attributes are pre-multiplied with the decode matrix
            // uniform in the shader (32-bit floating point)
            var decode = "";
            if (size === 5) {
              // separate scale and translate since glsl doesn't have mat5
              shader =
                "uniform mat4 " + decodeUniformVarNameScale + ";\n" + shader;
              shader =
                "uniform vec4 " + decodeUniformVarNameTranslate + ";\n" + shader;
              decode =
                "\n" +
                "void main() {\n" +
                "    " +
                decodedAttributeVarName +
                " = " +
                decodeUniformVarNameScale +
                " * " +
                attributeVarName +
                " + " +
                decodeUniformVarNameTranslate +
                ";\n" +
                "    " +
                newMain +
                "();\n" +
                "}\n";

              quantizedUniforms[decodeUniformVarNameScale] = { mat: 4 };
              quantizedUniforms[decodeUniformVarNameTranslate] = { vec: 4 };
            } else {
              shader =
                "uniform mat" +
                size +
                " " +
                decodeUniformVarName +
                ";\n" +
                shader;
              decode =
                "\n" +
                "void main() {\n" +
                "    " +
                decodedAttributeVarName +
                " = " +
                variableType +
                "(" +
                decodeUniformVarName +
                " * vec" +
                size +
                "(" +
                attributeVarName +
                ",1.0));\n" +
                "    " +
                newMain +
                "();\n" +
                "}\n";

              quantizedUniforms[decodeUniformVarName] = { mat: size };
            }
            shader = ShaderSource.replaceMain(shader, newMain);
            shader += decode;
          }
        }
      }
    }
    return {
      shader: shader,
      uniforms: quantizedUniforms,
    };
  };

  function getScalarUniformFunction(value) {
    var that = {
      value: value,
      clone: function (source, result) {
        return source;
      },
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  function getVec2UniformFunction(value) {
    var that = {
      value: Cartesian2.fromArray(value),
      clone: Cartesian2.clone,
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  function getVec3UniformFunction(value) {
    var that = {
      value: Cartesian3.fromArray(value),
      clone: Cartesian3.clone,
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  function getVec4UniformFunction(value) {
    var that = {
      value: Cartesian4.fromArray(value),
      clone: Cartesian4.clone,
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  function getMat2UniformFunction(value) {
    var that = {
      value: Matrix2.fromColumnMajorArray(value),
      clone: Matrix2.clone,
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  function getMat3UniformFunction(value) {
    var that = {
      value: Matrix3.fromColumnMajorArray(value),
      clone: Matrix3.clone,
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  function getMat4UniformFunction(value) {
    var that = {
      value: Matrix4.fromColumnMajorArray(value),
      clone: Matrix4.clone,
      func: function () {
        return that.value;
      },
    };
    return that;
  }

  ///////////////////////////////////////////////////////////////////////////

  function DelayLoadedTextureUniform(value, textures, defaultTexture) {
    this._value = undefined;
    this._textureId = value.index;
    this._textures = textures;
    this._defaultTexture = defaultTexture;
  }

  Object.defineProperties(DelayLoadedTextureUniform.prototype, {
    value: {
      get: function () {
        // Use the default texture (1x1 white) until the model's texture is loaded
        if (!defined(this._value)) {
          var texture = this._textures[this._textureId];
          if (defined(texture)) {
            this._value = texture;
          } else {
            return this._defaultTexture;
          }
        }

        return this._value;
      },
      set: function (value) {
        this._value = value;
      },
    },
  });

  DelayLoadedTextureUniform.prototype.clone = function (source) {
    return source;
  };

  DelayLoadedTextureUniform.prototype.func = undefined;

  ///////////////////////////////////////////////////////////////////////////

  function getTextureUniformFunction(value, textures, defaultTexture) {
    var uniform = new DelayLoadedTextureUniform(value, textures, defaultTexture);
    // Define function here to access closure since 'this' can't be
    // used when the Renderer sets uniforms.
    uniform.func = function () {
      return uniform.value;
    };
    return uniform;
  }

  var gltfUniformFunctions = {};
  gltfUniformFunctions[WebGLConstants$1.FLOAT] = getScalarUniformFunction;
  gltfUniformFunctions[WebGLConstants$1.FLOAT_VEC2] = getVec2UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.FLOAT_VEC3] = getVec3UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.FLOAT_VEC4] = getVec4UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.INT] = getScalarUniformFunction;
  gltfUniformFunctions[WebGLConstants$1.INT_VEC2] = getVec2UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.INT_VEC3] = getVec3UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.INT_VEC4] = getVec4UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.BOOL] = getScalarUniformFunction;
  gltfUniformFunctions[WebGLConstants$1.BOOL_VEC2] = getVec2UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.BOOL_VEC3] = getVec3UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.BOOL_VEC4] = getVec4UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.FLOAT_MAT2] = getMat2UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.FLOAT_MAT3] = getMat3UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.FLOAT_MAT4] = getMat4UniformFunction;
  gltfUniformFunctions[WebGLConstants$1.SAMPLER_2D] = getTextureUniformFunction;
  // GLTF_SPEC: Support SAMPLER_CUBE. https://github.com/KhronosGroup/glTF/issues/40

  ModelUtility.createUniformFunction = function (
    type,
    value,
    textures,
    defaultTexture
  ) {
    return gltfUniformFunctions[type](value, textures, defaultTexture);
  };

  function scaleFromMatrix5Array(matrix) {
    return [
      matrix[0],
      matrix[1],
      matrix[2],
      matrix[3],
      matrix[5],
      matrix[6],
      matrix[7],
      matrix[8],
      matrix[10],
      matrix[11],
      matrix[12],
      matrix[13],
      matrix[15],
      matrix[16],
      matrix[17],
      matrix[18],
    ];
  }

  function translateFromMatrix5Array(matrix) {
    return [matrix[20], matrix[21], matrix[22], matrix[23]];
  }

  ModelUtility.createUniformsForDracoQuantizedAttributes = function (
    decodedAttributes
  ) {
    var uniformMap = {};
    for (var attribute in decodedAttributes) {
      if (decodedAttributes.hasOwnProperty(attribute)) {
        var decodedData = decodedAttributes[attribute];
        var quantization = decodedData.quantization;

        if (!defined(quantization)) {
          continue;
        }

        if (attribute.charAt(0) === "_") {
          attribute = attribute.substring(1);
        }

        var uniformVarName = "gltf_u_dec_" + attribute.toLowerCase();

        if (quantization.octEncoded) {
          var uniformVarNameRangeConstant = uniformVarName + "_rangeConstant";
          var rangeConstant = (1 << quantization.quantizationBits) - 1.0;
          uniformMap[uniformVarNameRangeConstant] = getScalarUniformFunction(
            rangeConstant
          ).func;
          continue;
        }

        var uniformVarNameNormConstant = uniformVarName + "_normConstant";
        var normConstant =
          quantization.range / (1 << quantization.quantizationBits);
        uniformMap[uniformVarNameNormConstant] = getScalarUniformFunction(
          normConstant
        ).func;

        var uniformVarNameMin = uniformVarName + "_min";
        switch (decodedData.componentsPerAttribute) {
          case 1:
            uniformMap[uniformVarNameMin] = getScalarUniformFunction(
              quantization.minValues
            ).func;
            break;
          case 2:
            uniformMap[uniformVarNameMin] = getVec2UniformFunction(
              quantization.minValues
            ).func;
            break;
          case 3:
            uniformMap[uniformVarNameMin] = getVec3UniformFunction(
              quantization.minValues
            ).func;
            break;
          case 4:
            uniformMap[uniformVarNameMin] = getVec4UniformFunction(
              quantization.minValues
            ).func;
            break;
        }
      }
    }

    return uniformMap;
  };

  ModelUtility.createUniformsForQuantizedAttributes = function (
    gltf,
    primitive,
    quantizedUniforms
  ) {
    var accessors = gltf.accessors;
    var setUniforms = {};
    var uniformMap = {};

    var attributes = primitive.attributes;
    for (var attribute in attributes) {
      if (attributes.hasOwnProperty(attribute)) {
        var accessorId = attributes[attribute];
        var a = accessors[accessorId];
        var extensions = a.extensions;

        if (attribute.charAt(0) === "_") {
          attribute = attribute.substring(1);
        }

        if (defined(extensions)) {
          var quantizedAttributes = extensions.WEB3D_quantized_attributes;
          if (defined(quantizedAttributes)) {
            var decodeMatrix = quantizedAttributes.decodeMatrix;
            var uniformVariable = "gltf_u_dec_" + attribute.toLowerCase();

            switch (a.type) {
              case AttributeType$1.SCALAR:
                uniformMap[uniformVariable] = getMat2UniformFunction(
                  decodeMatrix
                ).func;
                setUniforms[uniformVariable] = true;
                break;
              case AttributeType$1.VEC2:
                uniformMap[uniformVariable] = getMat3UniformFunction(
                  decodeMatrix
                ).func;
                setUniforms[uniformVariable] = true;
                break;
              case AttributeType$1.VEC3:
                uniformMap[uniformVariable] = getMat4UniformFunction(
                  decodeMatrix
                ).func;
                setUniforms[uniformVariable] = true;
                break;
              case AttributeType$1.VEC4:
                // VEC4 attributes are split into scale and translate because there is no mat5 in GLSL
                var uniformVariableScale = uniformVariable + "_scale";
                var uniformVariableTranslate = uniformVariable + "_translate";
                uniformMap[uniformVariableScale] = getMat4UniformFunction(
                  scaleFromMatrix5Array(decodeMatrix)
                ).func;
                uniformMap[uniformVariableTranslate] = getVec4UniformFunction(
                  translateFromMatrix5Array(decodeMatrix)
                ).func;
                setUniforms[uniformVariableScale] = true;
                setUniforms[uniformVariableTranslate] = true;
                break;
            }
          }
        }
      }
    }

    // If there are any unset quantized uniforms in this program, they should be set to the identity
    for (var quantizedUniform in quantizedUniforms) {
      if (quantizedUniforms.hasOwnProperty(quantizedUniform)) {
        if (!setUniforms[quantizedUniform]) {
          var properties = quantizedUniforms[quantizedUniform];
          if (defined(properties.mat)) {
            if (properties.mat === 2) {
              uniformMap[quantizedUniform] = getMat2UniformFunction(
                Matrix2.IDENTITY
              ).func;
            } else if (properties.mat === 3) {
              uniformMap[quantizedUniform] = getMat3UniformFunction(
                Matrix3.IDENTITY
              ).func;
            } else if (properties.mat === 4) {
              uniformMap[quantizedUniform] = getMat4UniformFunction(
                Matrix4.IDENTITY
              ).func;
            }
          }
          if (defined(properties.vec)) {
            if (properties.vec === 4) {
              uniformMap[quantizedUniform] = getVec4UniformFunction([
                0,
                0,
                0,
                0,
              ]).func;
            }
          }
        }
      }
    }
    return uniformMap;
  };

  // This doesn't support LOCAL, which we could add if it is ever used.
  var scratchTranslationRtc = new Cartesian3();
  var gltfSemanticUniforms = {
    MODEL: function (uniformState, model) {
      return function () {
        return uniformState.model;
      };
    },
    VIEW: function (uniformState, model) {
      return function () {
        return uniformState.view;
      };
    },
    PROJECTION: function (uniformState, model) {
      return function () {
        return uniformState.projection;
      };
    },
    MODELVIEW: function (uniformState, model) {
      return function () {
        return uniformState.modelView;
      };
    },
    CESIUM_RTC_MODELVIEW: function (uniformState, model) {
      // CESIUM_RTC extension
      var mvRtc = new Matrix4();
      return function () {
        if (defined(model._rtcCenter)) {
          Matrix4.getTranslation(uniformState.model, scratchTranslationRtc);
          Cartesian3.add(
            scratchTranslationRtc,
            model._rtcCenter,
            scratchTranslationRtc
          );
          Matrix4.multiplyByPoint(
            uniformState.view,
            scratchTranslationRtc,
            scratchTranslationRtc
          );
          return Matrix4.setTranslation(
            uniformState.modelView,
            scratchTranslationRtc,
            mvRtc
          );
        }
        return uniformState.modelView;
      };
    },
    MODELVIEWPROJECTION: function (uniformState, model) {
      return function () {
        return uniformState.modelViewProjection;
      };
    },
    MODELINVERSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseModel;
      };
    },
    VIEWINVERSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseView;
      };
    },
    PROJECTIONINVERSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseProjection;
      };
    },
    MODELVIEWINVERSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseModelView;
      };
    },
    MODELVIEWPROJECTIONINVERSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseModelViewProjection;
      };
    },
    MODELINVERSETRANSPOSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseTransposeModel;
      };
    },
    MODELVIEWINVERSETRANSPOSE: function (uniformState, model) {
      return function () {
        return uniformState.normal;
      };
    },
    VIEWPORT: function (uniformState, model) {
      return function () {
        return uniformState.viewportCartesian4;
      };
    },
    // JOINTMATRIX created in createCommand()
  };

  ModelUtility.getGltfSemanticUniforms = function () {
    return gltfSemanticUniforms;
  };

  /**
   * @private
   */
  function processModelMaterialsCommon(gltf, options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    if (!defined(gltf)) {
      return;
    }

    if (!hasExtension(gltf, "KHR_materials_common")) {
      return;
    }

    if (!hasExtension(gltf, "KHR_techniques_webgl")) {
      if (!defined(gltf.extensions)) {
        gltf.extensions = {};
      }

      gltf.extensions.KHR_techniques_webgl = {
        programs: [],
        shaders: [],
        techniques: [],
      };
      gltf.extensionsUsed.push("KHR_techniques_webgl");
      gltf.extensionsRequired.push("KHR_techniques_webgl");
    }

    var techniquesWebgl = gltf.extensions.KHR_techniques_webgl;

    lightDefaults(gltf);

    var lightParameters = generateLightParameters(gltf);

    var primitiveByMaterial = ModelUtility.splitIncompatibleMaterials(gltf);

    var techniques = {};
    var generatedTechniques = false;
    ForEach.material(gltf, function (material, materialIndex) {
      if (
        defined(material.extensions) &&
        defined(material.extensions.KHR_materials_common)
      ) {
        var khrMaterialsCommon = material.extensions.KHR_materials_common;
        var primitiveInfo = primitiveByMaterial[materialIndex];

        var techniqueKey = getTechniqueKey(khrMaterialsCommon, primitiveInfo);
        var technique = techniques[techniqueKey];

        if (!defined(technique)) {
          technique = generateTechnique(
            gltf,
            techniquesWebgl,
            primitiveInfo,
            khrMaterialsCommon,
            lightParameters,
            options.addBatchIdToGeneratedShaders
          );
          techniques[techniqueKey] = technique;
          generatedTechniques = true;
        }

        var materialValues = {};
        var values = khrMaterialsCommon.values;
        var uniformName;
        for (var valueName in values) {
          if (
            values.hasOwnProperty(valueName) &&
            valueName !== "transparent" &&
            valueName !== "doubleSided"
          ) {
            uniformName = "u_" + valueName.toLowerCase();
            materialValues[uniformName] = values[valueName];
          }
        }

        material.extensions.KHR_techniques_webgl = {
          technique: technique,
          values: materialValues,
        };

        material.alphaMode = "OPAQUE";
        if (khrMaterialsCommon.transparent) {
          material.alphaMode = "BLEND";
        }

        if (khrMaterialsCommon.doubleSided) {
          material.doubleSided = true;
        }
      }
    });

    if (!generatedTechniques) {
      return gltf;
    }

    // If any primitives have semantics that aren't declared in the generated
    // shaders, we want to preserve them.
    ModelUtility.ensureSemanticExistence(gltf);

    return gltf;
  }

  function generateLightParameters(gltf) {
    var result = {};

    var lights;
    if (
      defined(gltf.extensions) &&
      defined(gltf.extensions.KHR_materials_common)
    ) {
      lights = gltf.extensions.KHR_materials_common.lights;
    }

    if (defined(lights)) {
      // Figure out which node references the light
      var nodes = gltf.nodes;
      for (var nodeName in nodes) {
        if (nodes.hasOwnProperty(nodeName)) {
          var node = nodes[nodeName];
          if (
            defined(node.extensions) &&
            defined(node.extensions.KHR_materials_common)
          ) {
            var nodeLightId = node.extensions.KHR_materials_common.light;
            if (defined(nodeLightId) && defined(lights[nodeLightId])) {
              lights[nodeLightId].node = nodeName;
            }
            delete node.extensions.KHR_materials_common;
          }
        }
      }

      // Add light parameters to result
      var lightCount = 0;
      for (var lightName in lights) {
        if (lights.hasOwnProperty(lightName)) {
          var light = lights[lightName];
          var lightType = light.type;
          if (lightType !== "ambient" && !defined(light.node)) {
            delete lights[lightName];
            continue;
          }
          var lightBaseName = "light" + lightCount.toString();
          light.baseName = lightBaseName;
          switch (lightType) {
            case "ambient":
              var ambient = light.ambient;
              result[lightBaseName + "Color"] = {
                type: WebGLConstants$1.FLOAT_VEC3,
                value: ambient.color,
              };
              break;
            case "directional":
              var directional = light.directional;
              result[lightBaseName + "Color"] = {
                type: WebGLConstants$1.FLOAT_VEC3,
                value: directional.color,
              };
              if (defined(light.node)) {
                result[lightBaseName + "Transform"] = {
                  node: light.node,
                  semantic: "MODELVIEW",
                  type: WebGLConstants$1.FLOAT_MAT4,
                };
              }
              break;
            case "point":
              var point = light.point;
              result[lightBaseName + "Color"] = {
                type: WebGLConstants$1.FLOAT_VEC3,
                value: point.color,
              };
              if (defined(light.node)) {
                result[lightBaseName + "Transform"] = {
                  node: light.node,
                  semantic: "MODELVIEW",
                  type: WebGLConstants$1.FLOAT_MAT4,
                };
              }
              result[lightBaseName + "Attenuation"] = {
                type: WebGLConstants$1.FLOAT_VEC3,
                value: [
                  point.constantAttenuation,
                  point.linearAttenuation,
                  point.quadraticAttenuation,
                ],
              };
              break;
            case "spot":
              var spot = light.spot;
              result[lightBaseName + "Color"] = {
                type: WebGLConstants$1.FLOAT_VEC3,
                value: spot.color,
              };
              if (defined(light.node)) {
                result[lightBaseName + "Transform"] = {
                  node: light.node,
                  semantic: "MODELVIEW",
                  type: WebGLConstants$1.FLOAT_MAT4,
                };
                result[lightBaseName + "InverseTransform"] = {
                  node: light.node,
                  semantic: "MODELVIEWINVERSE",
                  type: WebGLConstants$1.FLOAT_MAT4,
                  useInFragment: true,
                };
              }
              result[lightBaseName + "Attenuation"] = {
                type: WebGLConstants$1.FLOAT_VEC3,
                value: [
                  spot.constantAttenuation,
                  spot.linearAttenuation,
                  spot.quadraticAttenuation,
                ],
              };

              result[lightBaseName + "FallOff"] = {
                type: WebGLConstants$1.FLOAT_VEC2,
                value: [spot.fallOffAngle, spot.fallOffExponent],
              };
              break;
          }
          ++lightCount;
        }
      }
    }

    return result;
  }

  function generateTechnique(
    gltf,
    techniquesWebgl,
    primitiveInfo,
    khrMaterialsCommon,
    lightParameters,
    addBatchIdToGeneratedShaders
  ) {
    if (!defined(khrMaterialsCommon)) {
      khrMaterialsCommon = {};
    }

    addBatchIdToGeneratedShaders = defaultValue(
      addBatchIdToGeneratedShaders,
      false
    );

    var techniques = techniquesWebgl.techniques;
    var shaders = techniquesWebgl.shaders;
    var programs = techniquesWebgl.programs;
    var lightingModel = khrMaterialsCommon.technique.toUpperCase();
    var lights;
    if (
      defined(gltf.extensions) &&
      defined(gltf.extensions.KHR_materials_common)
    ) {
      lights = gltf.extensions.KHR_materials_common.lights;
    }

    var parameterValues = khrMaterialsCommon.values;
    var jointCount = defaultValue(khrMaterialsCommon.jointCount, 0);

    var skinningInfo;
    var hasSkinning = false;
    var hasVertexColors = false;

    if (defined(primitiveInfo)) {
      skinningInfo = primitiveInfo.skinning;
      hasSkinning = skinningInfo.skinned;
      hasVertexColors = primitiveInfo.hasVertexColors;
    }

    var vertexShader = "precision highp float;\n";
    var fragmentShader = "precision highp float;\n";

    var hasNormals = lightingModel !== "CONSTANT";

    // Add techniques
    var techniqueUniforms = {
      u_modelViewMatrix: {
        semantic: hasExtension(gltf, "CESIUM_RTC")
          ? "CESIUM_RTC_MODELVIEW"
          : "MODELVIEW",
        type: WebGLConstants$1.FLOAT_MAT4,
      },
      u_projectionMatrix: {
        semantic: "PROJECTION",
        type: WebGLConstants$1.FLOAT_MAT4,
      },
    };

    if (hasNormals) {
      techniqueUniforms.u_normalMatrix = {
        semantic: "MODELVIEWINVERSETRANSPOSE",
        type: WebGLConstants$1.FLOAT_MAT3,
      };
    }

    if (hasSkinning) {
      techniqueUniforms.u_jointMatrix = {
        count: jointCount,
        semantic: "JOINTMATRIX",
        type: WebGLConstants$1.FLOAT_MAT4,
      };
    }

    // Add material values
    var uniformName;
    var hasTexCoords = false;
    for (var name in parameterValues) {
      //generate shader parameters for KHR_materials_common attributes
      //(including a check, because some boolean flags should not be used as shader parameters)
      if (
        parameterValues.hasOwnProperty(name) &&
        name !== "transparent" &&
        name !== "doubleSided"
      ) {
        var uniformType = getKHRMaterialsCommonValueType(
          name,
          parameterValues[name]
        );
        uniformName = "u_" + name.toLowerCase();
        if (!hasTexCoords && uniformType === WebGLConstants$1.SAMPLER_2D) {
          hasTexCoords = true;
        }

        techniqueUniforms[uniformName] = {
          type: uniformType,
        };
      }
    }

    // Give the diffuse uniform a semantic to support color replacement in 3D Tiles
    if (defined(techniqueUniforms.u_diffuse)) {
      techniqueUniforms.u_diffuse.semantic = "_3DTILESDIFFUSE";
    }

    // Copy light parameters into technique parameters
    if (defined(lightParameters)) {
      for (var lightParamName in lightParameters) {
        if (lightParameters.hasOwnProperty(lightParamName)) {
          uniformName = "u_" + lightParamName;
          techniqueUniforms[uniformName] = lightParameters[lightParamName];
        }
      }
    }

    // Add uniforms to shaders
    for (uniformName in techniqueUniforms) {
      if (techniqueUniforms.hasOwnProperty(uniformName)) {
        var uniform = techniqueUniforms[uniformName];
        var arraySize = defined(uniform.count) ? "[" + uniform.count + "]" : "";
        if (
          (uniform.type !== WebGLConstants$1.FLOAT_MAT3 &&
            uniform.type !== WebGLConstants$1.FLOAT_MAT4) ||
          uniform.useInFragment
        ) {
          fragmentShader +=
            "uniform " +
            webGLConstantToGlslType(uniform.type) +
            " " +
            uniformName +
            arraySize +
            ";\n";
          delete uniform.useInFragment;
        } else {
          vertexShader +=
            "uniform " +
            webGLConstantToGlslType(uniform.type) +
            " " +
            uniformName +
            arraySize +
            ";\n";
        }
      }
    }

    // Add attributes with semantics
    var vertexShaderMain = "";
    if (hasSkinning) {
      vertexShaderMain +=
        "    mat4 skinMatrix =\n" +
        "        a_weight.x * u_jointMatrix[int(a_joint.x)] +\n" +
        "        a_weight.y * u_jointMatrix[int(a_joint.y)] +\n" +
        "        a_weight.z * u_jointMatrix[int(a_joint.z)] +\n" +
        "        a_weight.w * u_jointMatrix[int(a_joint.w)];\n";
    }

    // Add position always
    var techniqueAttributes = {
      a_position: {
        semantic: "POSITION",
      },
    };
    vertexShader += "attribute vec3 a_position;\n";
    vertexShader += "varying vec3 v_positionEC;\n";
    if (hasSkinning) {
      vertexShaderMain +=
        "  vec4 pos = u_modelViewMatrix * skinMatrix * vec4(a_position,1.0);\n";
    } else {
      vertexShaderMain +=
        "  vec4 pos = u_modelViewMatrix * vec4(a_position,1.0);\n";
    }
    vertexShaderMain += "  v_positionEC = pos.xyz;\n";
    vertexShaderMain += "  gl_Position = u_projectionMatrix * pos;\n";
    fragmentShader += "varying vec3 v_positionEC;\n";

    // Add normal if we don't have constant lighting
    if (hasNormals) {
      techniqueAttributes.a_normal = {
        semantic: "NORMAL",
      };
      vertexShader += "attribute vec3 a_normal;\n";
      vertexShader += "varying vec3 v_normal;\n";
      if (hasSkinning) {
        vertexShaderMain +=
          "  v_normal = u_normalMatrix * mat3(skinMatrix) * a_normal;\n";
      } else {
        vertexShaderMain += "  v_normal = u_normalMatrix * a_normal;\n";
      }

      fragmentShader += "varying vec3 v_normal;\n";
    }

    // Add texture coordinates if the material uses them
    var v_texcoord;
    if (hasTexCoords) {
      techniqueAttributes.a_texcoord_0 = {
        semantic: "TEXCOORD_0",
      };

      v_texcoord = "v_texcoord_0";
      vertexShader += "attribute vec2 a_texcoord_0;\n";
      vertexShader += "varying vec2 " + v_texcoord + ";\n";
      vertexShaderMain += "  " + v_texcoord + " = a_texcoord_0;\n";

      fragmentShader += "varying vec2 " + v_texcoord + ";\n";
    }

    if (hasSkinning) {
      techniqueAttributes.a_joint = {
        semantic: "JOINTS_0",
      };
      techniqueAttributes.a_weight = {
        semantic: "WEIGHTS_0",
      };

      vertexShader += "attribute vec4 a_joint;\n";
      vertexShader += "attribute vec4 a_weight;\n";
    }

    if (hasVertexColors) {
      techniqueAttributes.a_vertexColor = {
        semantic: "COLOR_0",
      };
      vertexShader += "attribute vec4 a_vertexColor;\n";
      vertexShader += "varying vec4 v_vertexColor;\n";
      vertexShaderMain += "  v_vertexColor = a_vertexColor;\n";
      fragmentShader += "varying vec4 v_vertexColor;\n";
    }

    if (addBatchIdToGeneratedShaders) {
      techniqueAttributes.a_batchId = {
        semantic: "_BATCHID",
      };
      vertexShader += "attribute float a_batchId;\n";
    }

    var hasSpecular =
      hasNormals &&
      (lightingModel === "BLINN" || lightingModel === "PHONG") &&
      defined(techniqueUniforms.u_specular) &&
      defined(techniqueUniforms.u_shininess) &&
      techniqueUniforms.u_shininess > 0.0;

    // Generate lighting code blocks
    var hasNonAmbientLights = false;
    var hasAmbientLights = false;
    var fragmentLightingBlock = "";
    for (var lightName in lights) {
      if (lights.hasOwnProperty(lightName)) {
        var light = lights[lightName];
        var lightType = light.type.toLowerCase();
        var lightBaseName = light.baseName;
        fragmentLightingBlock += "  {\n";
        var lightColorName = "u_" + lightBaseName + "Color";
        var varyingDirectionName;
        var varyingPositionName;
        if (lightType === "ambient") {
          hasAmbientLights = true;
          fragmentLightingBlock +=
            "    ambientLight += " + lightColorName + ";\n";
        } else if (hasNormals) {
          hasNonAmbientLights = true;
          varyingDirectionName = "v_" + lightBaseName + "Direction";
          varyingPositionName = "v_" + lightBaseName + "Position";

          if (lightType !== "point") {
            vertexShader += "varying vec3 " + varyingDirectionName + ";\n";
            fragmentShader += "varying vec3 " + varyingDirectionName + ";\n";

            vertexShaderMain +=
              "  " +
              varyingDirectionName +
              " = mat3(u_" +
              lightBaseName +
              "Transform) * vec3(0.,0.,1.);\n";
            if (lightType === "directional") {
              fragmentLightingBlock +=
                "    vec3 l = normalize(" + varyingDirectionName + ");\n";
            }
          }

          if (lightType !== "directional") {
            vertexShader += "varying vec3 " + varyingPositionName + ";\n";
            fragmentShader += "varying vec3 " + varyingPositionName + ";\n";

            vertexShaderMain +=
              "  " +
              varyingPositionName +
              " = u_" +
              lightBaseName +
              "Transform[3].xyz;\n";
            fragmentLightingBlock +=
              "    vec3 VP = " + varyingPositionName + " - v_positionEC;\n";
            fragmentLightingBlock += "    vec3 l = normalize(VP);\n";
            fragmentLightingBlock += "    float range = length(VP);\n";
            fragmentLightingBlock +=
              "    float attenuation = 1.0 / (u_" +
              lightBaseName +
              "Attenuation.x + ";
            fragmentLightingBlock +=
              "(u_" + lightBaseName + "Attenuation.y * range) + ";
            fragmentLightingBlock +=
              "(u_" + lightBaseName + "Attenuation.z * range * range));\n";
          } else {
            fragmentLightingBlock += "    float attenuation = 1.0;\n";
          }

          if (lightType === "spot") {
            fragmentLightingBlock +=
              "    float spotDot = dot(l, normalize(" +
              varyingDirectionName +
              "));\n";
            fragmentLightingBlock +=
              "    if (spotDot < cos(u_" + lightBaseName + "FallOff.x * 0.5))\n";
            fragmentLightingBlock += "    {\n";
            fragmentLightingBlock += "      attenuation = 0.0;\n";
            fragmentLightingBlock += "    }\n";
            fragmentLightingBlock += "    else\n";
            fragmentLightingBlock += "    {\n";
            fragmentLightingBlock +=
              "        attenuation *= max(0.0, pow(spotDot, u_" +
              lightBaseName +
              "FallOff.y));\n";
            fragmentLightingBlock += "    }\n";
          }

          fragmentLightingBlock +=
            "    diffuseLight += " +
            lightColorName +
            "* max(dot(normal,l), 0.) * attenuation;\n";

          if (hasSpecular) {
            if (lightingModel === "BLINN") {
              fragmentLightingBlock += "    vec3 h = normalize(l + viewDir);\n";
              fragmentLightingBlock +=
                "    float specularIntensity = max(0., pow(max(dot(normal, h), 0.), u_shininess)) * attenuation;\n";
            } else {
              // PHONG
              fragmentLightingBlock +=
                "    vec3 reflectDir = reflect(-l, normal);\n";
              fragmentLightingBlock +=
                "    float specularIntensity = max(0., pow(max(dot(reflectDir, viewDir), 0.), u_shininess)) * attenuation;\n";
            }
            fragmentLightingBlock +=
              "    specularLight += " +
              lightColorName +
              " * specularIntensity;\n";
          }
        }
        fragmentLightingBlock += "  }\n";
      }
    }

    if (!hasAmbientLights) {
      // Add an ambient light if we don't have one
      fragmentLightingBlock += "  ambientLight += vec3(0.2, 0.2, 0.2);\n";
    }

    if (!hasNonAmbientLights && lightingModel !== "CONSTANT") {
      fragmentShader += "#ifdef USE_CUSTOM_LIGHT_COLOR \n";
      fragmentShader += "uniform vec3 gltf_lightColor; \n";
      fragmentShader += "#endif \n";

      fragmentLightingBlock += "#ifndef USE_CUSTOM_LIGHT_COLOR \n";
      fragmentLightingBlock += "    vec3 lightColor = czm_lightColor;\n";
      fragmentLightingBlock += "#else \n";
      fragmentLightingBlock += "    vec3 lightColor = gltf_lightColor;\n";
      fragmentLightingBlock += "#endif \n";

      fragmentLightingBlock += "  vec3 l = normalize(czm_lightDirectionEC);\n";
      var minimumLighting = "0.2"; // Use strings instead of values as 0.0 -> 0 when stringified
      fragmentLightingBlock +=
        "  diffuseLight += lightColor * max(dot(normal,l), " +
        minimumLighting +
        ");\n";

      if (hasSpecular) {
        if (lightingModel === "BLINN") {
          fragmentLightingBlock += "  vec3 h = normalize(l + viewDir);\n";
          fragmentLightingBlock +=
            "  float specularIntensity = max(0., pow(max(dot(normal, h), 0.), u_shininess));\n";
        } else {
          // PHONG
          fragmentLightingBlock += "  vec3 reflectDir = reflect(-l, normal);\n";
          fragmentLightingBlock +=
            "  float specularIntensity = max(0., pow(max(dot(reflectDir, viewDir), 0.), u_shininess));\n";
        }

        fragmentLightingBlock +=
          "  specularLight += lightColor * specularIntensity;\n";
      }
    }

    vertexShader += "void main(void) {\n";
    vertexShader += vertexShaderMain;
    vertexShader += "}\n";

    fragmentShader += "void main(void) {\n";
    var colorCreationBlock = "  vec3 color = vec3(0.0, 0.0, 0.0);\n";
    if (hasNormals) {
      fragmentShader += "  vec3 normal = normalize(v_normal);\n";
      if (khrMaterialsCommon.doubleSided) {
        fragmentShader += "  if (czm_backFacing())\n";
        fragmentShader += "  {\n";
        fragmentShader += "    normal = -normal;\n";
        fragmentShader += "  }\n";
      }
    }

    var finalColorComputation;
    if (lightingModel !== "CONSTANT") {
      if (defined(techniqueUniforms.u_diffuse)) {
        if (techniqueUniforms.u_diffuse.type === WebGLConstants$1.SAMPLER_2D) {
          fragmentShader +=
            "  vec4 diffuse = texture2D(u_diffuse, " + v_texcoord + ");\n";
        } else {
          fragmentShader += "  vec4 diffuse = u_diffuse;\n";
        }
        fragmentShader += "  vec3 diffuseLight = vec3(0.0, 0.0, 0.0);\n";
        colorCreationBlock += "  color += diffuse.rgb * diffuseLight;\n";
      }

      if (hasSpecular) {
        if (techniqueUniforms.u_specular.type === WebGLConstants$1.SAMPLER_2D) {
          fragmentShader +=
            "  vec3 specular = texture2D(u_specular, " + v_texcoord + ").rgb;\n";
        } else {
          fragmentShader += "  vec3 specular = u_specular.rgb;\n";
        }
        fragmentShader += "  vec3 specularLight = vec3(0.0, 0.0, 0.0);\n";
        colorCreationBlock += "  color += specular * specularLight;\n";
      }

      if (defined(techniqueUniforms.u_transparency)) {
        finalColorComputation =
          "  gl_FragColor = vec4(color * diffuse.a * u_transparency, diffuse.a * u_transparency);\n";
      } else {
        finalColorComputation =
          "  gl_FragColor = vec4(color * diffuse.a, diffuse.a);\n";
      }
    } else if (defined(techniqueUniforms.u_transparency)) {
      finalColorComputation =
        "  gl_FragColor = vec4(color * u_transparency, u_transparency);\n";
    } else {
      finalColorComputation = "  gl_FragColor = vec4(color, 1.0);\n";
    }

    if (hasVertexColors) {
      colorCreationBlock += "  color *= v_vertexColor.rgb;\n";
    }

    if (defined(techniqueUniforms.u_emission)) {
      if (techniqueUniforms.u_emission.type === WebGLConstants$1.SAMPLER_2D) {
        fragmentShader +=
          "  vec3 emission = texture2D(u_emission, " + v_texcoord + ").rgb;\n";
      } else {
        fragmentShader += "  vec3 emission = u_emission.rgb;\n";
      }
      colorCreationBlock += "  color += emission;\n";
    }

    if (defined(techniqueUniforms.u_ambient) || lightingModel !== "CONSTANT") {
      if (defined(techniqueUniforms.u_ambient)) {
        if (techniqueUniforms.u_ambient.type === WebGLConstants$1.SAMPLER_2D) {
          fragmentShader +=
            "  vec3 ambient = texture2D(u_ambient, " + v_texcoord + ").rgb;\n";
        } else {
          fragmentShader += "  vec3 ambient = u_ambient.rgb;\n";
        }
      } else {
        fragmentShader += "  vec3 ambient = diffuse.rgb;\n";
      }
      colorCreationBlock += "  color += ambient * ambientLight;\n";
    }
    fragmentShader += "  vec3 viewDir = -normalize(v_positionEC);\n";
    fragmentShader += "  vec3 ambientLight = vec3(0.0, 0.0, 0.0);\n";

    // Add in light computations
    fragmentShader += fragmentLightingBlock;

    fragmentShader += colorCreationBlock;
    fragmentShader += finalColorComputation;
    fragmentShader += "}\n";

    // Add shaders
    var vertexShaderId = addToArray(shaders, {
      type: WebGLConstants$1.VERTEX_SHADER,
      extras: {
        _pipeline: {
          source: vertexShader,
          extension: ".glsl",
        },
      },
    });

    var fragmentShaderId = addToArray(shaders, {
      type: WebGLConstants$1.FRAGMENT_SHADER,
      extras: {
        _pipeline: {
          source: fragmentShader,
          extension: ".glsl",
        },
      },
    });

    // Add program
    var programId = addToArray(programs, {
      fragmentShader: fragmentShaderId,
      vertexShader: vertexShaderId,
    });

    var techniqueId = addToArray(techniques, {
      attributes: techniqueAttributes,
      program: programId,
      uniforms: techniqueUniforms,
    });

    return techniqueId;
  }

  function getKHRMaterialsCommonValueType(paramName, paramValue) {
    var value;

    // Backwards compatibility for COLLADA2GLTF v1.0-draft when it encoding
    // materials using KHR_materials_common with explicit type/value members
    if (defined(paramValue.value)) {
      value = paramValue.value;
    } else if (defined(paramValue.index)) {
      value = [paramValue.index];
    } else {
      value = paramValue;
    }

    switch (paramName) {
      case "ambient":
        return value.length === 1
          ? WebGLConstants$1.SAMPLER_2D
          : WebGLConstants$1.FLOAT_VEC4;
      case "diffuse":
        return value.length === 1
          ? WebGLConstants$1.SAMPLER_2D
          : WebGLConstants$1.FLOAT_VEC4;
      case "emission":
        return value.length === 1
          ? WebGLConstants$1.SAMPLER_2D
          : WebGLConstants$1.FLOAT_VEC4;
      case "specular":
        return value.length === 1
          ? WebGLConstants$1.SAMPLER_2D
          : WebGLConstants$1.FLOAT_VEC4;
      case "shininess":
        return WebGLConstants$1.FLOAT;
      case "transparency":
        return WebGLConstants$1.FLOAT;

      // these two are usually not used directly within shaders,
      // they are just added here for completeness
      case "transparent":
        return WebGLConstants$1.BOOL;
      case "doubleSided":
        return WebGLConstants$1.BOOL;
    }
  }

  function getTechniqueKey(khrMaterialsCommon, primitiveInfo) {
    var techniqueKey = "";
    techniqueKey += "technique:" + khrMaterialsCommon.technique + ";";

    var values = khrMaterialsCommon.values;
    var keys = Object.keys(values).sort();
    var keysCount = keys.length;
    for (var i = 0; i < keysCount; ++i) {
      var name = keys[i];
      if (values.hasOwnProperty(name)) {
        techniqueKey +=
          name + ":" + getKHRMaterialsCommonValueType(name, values[name]);
        techniqueKey += ";";
      }
    }

    var jointCount = defaultValue(khrMaterialsCommon.jointCount, 0);
    techniqueKey += jointCount.toString() + ";";
    if (defined(primitiveInfo)) {
      var skinningInfo = primitiveInfo.skinning;
      if (jointCount > 0) {
        techniqueKey += skinningInfo.type + ";";
      }
      techniqueKey += primitiveInfo.hasVertexColors;
    }

    return techniqueKey;
  }

  function lightDefaults(gltf) {
    var khrMaterialsCommon = gltf.extensions.KHR_materials_common;
    if (!defined(khrMaterialsCommon) || !defined(khrMaterialsCommon.lights)) {
      return;
    }

    var lights = khrMaterialsCommon.lights;

    var lightsLength = lights.length;
    for (var lightId = 0; lightId < lightsLength; lightId++) {
      var light = lights[lightId];
      if (light.type === "ambient") {
        if (!defined(light.ambient)) {
          light.ambient = {};
        }
        var ambientLight = light.ambient;

        if (!defined(ambientLight.color)) {
          ambientLight.color = [1.0, 1.0, 1.0];
        }
      } else if (light.type === "directional") {
        if (!defined(light.directional)) {
          light.directional = {};
        }
        var directionalLight = light.directional;

        if (!defined(directionalLight.color)) {
          directionalLight.color = [1.0, 1.0, 1.0];
        }
      } else if (light.type === "point") {
        if (!defined(light.point)) {
          light.point = {};
        }
        var pointLight = light.point;

        if (!defined(pointLight.color)) {
          pointLight.color = [1.0, 1.0, 1.0];
        }

        pointLight.constantAttenuation = defaultValue(
          pointLight.constantAttenuation,
          1.0
        );
        pointLight.linearAttenuation = defaultValue(
          pointLight.linearAttenuation,
          0.0
        );
        pointLight.quadraticAttenuation = defaultValue(
          pointLight.quadraticAttenuation,
          0.0
        );
      } else if (light.type === "spot") {
        if (!defined(light.spot)) {
          light.spot = {};
        }
        var spotLight = light.spot;

        if (!defined(spotLight.color)) {
          spotLight.color = [1.0, 1.0, 1.0];
        }

        spotLight.constantAttenuation = defaultValue(
          spotLight.constantAttenuation,
          1.0
        );
        spotLight.fallOffAngle = defaultValue(spotLight.fallOffAngle, 3.14159265);
        spotLight.fallOffExponent = defaultValue(spotLight.fallOffExponent, 0.0);
        spotLight.linearAttenuation = defaultValue(
          spotLight.linearAttenuation,
          0.0
        );
        spotLight.quadraticAttenuation = defaultValue(
          spotLight.quadraticAttenuation,
          0.0
        );
      }
    }
  }

  /**
   * @private
   */
  function processPbrMaterials(gltf, options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    // No need to create new techniques if they already exist,
    // the shader should handle these values
    if (hasExtension(gltf, "KHR_techniques_webgl")) {
      return gltf;
    }

    // All materials in glTF are PBR by default,
    // so we should apply PBR unless no materials are found.
    if (!defined(gltf.materials) || gltf.materials.length === 0) {
      return gltf;
    }

    if (!defined(gltf.extensions)) {
      gltf.extensions = {};
    }

    if (!defined(gltf.extensionsUsed)) {
      gltf.extensionsUsed = [];
    }

    if (!defined(gltf.extensionsRequired)) {
      gltf.extensionsRequired = [];
    }

    gltf.extensions.KHR_techniques_webgl = {
      programs: [],
      shaders: [],
      techniques: [],
    };

    gltf.extensionsUsed.push("KHR_techniques_webgl");
    gltf.extensionsRequired.push("KHR_techniques_webgl");

    var primitiveByMaterial = ModelUtility.splitIncompatibleMaterials(gltf);

    ForEach.material(gltf, function (material, materialIndex) {
      var generatedMaterialValues = {};
      var technique = generateTechnique$1(
        gltf,
        material,
        materialIndex,
        generatedMaterialValues,
        primitiveByMaterial,
        options
      );

      if (!defined(material.extensions)) {
        material.extensions = {};
      }

      material.extensions.KHR_techniques_webgl = {
        values: generatedMaterialValues,
        technique: technique,
      };
    });

    // If any primitives have semantics that aren't declared in the generated
    // shaders, we want to preserve them.
    ModelUtility.ensureSemanticExistence(gltf);

    return gltf;
  }

  function isSpecularGlossinessMaterial(material) {
    return (
      defined(material.extensions) &&
      defined(material.extensions.KHR_materials_pbrSpecularGlossiness)
    );
  }

  function addTextureCoordinates(
    gltf,
    textureName,
    generatedMaterialValues,
    defaultTexCoord,
    result
  ) {
    var texCoord;
    var texInfo = generatedMaterialValues[textureName];
    if (defined(texInfo) && defined(texInfo.texCoord) && texInfo.texCoord === 1) {
      defaultTexCoord = defaultTexCoord.replace("0", "1");
    }
    if (defined(generatedMaterialValues[textureName + "Offset"])) {
      texCoord = textureName + "Coord";
      result.fragmentShaderMain +=
        "    vec2 " +
        texCoord +
        " = computeTexCoord(" +
        defaultTexCoord +
        ", " +
        textureName +
        "Offset, " +
        textureName +
        "Rotation, " +
        textureName +
        "Scale);\n";
    } else {
      texCoord = defaultTexCoord;
    }
    return texCoord;
  }

  var DEFAULT_TEXTURE_OFFSET = [0.0, 0.0];
  var DEFAULT_TEXTURE_ROTATION = [0.0];
  var DEFAULT_TEXTURE_SCALE = [1.0, 1.0];

  function handleKHRTextureTransform(
    parameterName,
    value,
    generatedMaterialValues
  ) {
    if (
      parameterName.indexOf("Texture") === -1 ||
      !defined(value.extensions) ||
      !defined(value.extensions.KHR_texture_transform)
    ) {
      return;
    }

    var uniformName = "u_" + parameterName;
    var extension = value.extensions.KHR_texture_transform;
    generatedMaterialValues[uniformName + "Offset"] = defaultValue(
      extension.offset,
      DEFAULT_TEXTURE_OFFSET
    );
    generatedMaterialValues[uniformName + "Rotation"] = defaultValue(
      extension.rotation,
      DEFAULT_TEXTURE_ROTATION
    );
    generatedMaterialValues[uniformName + "Scale"] = defaultValue(
      extension.scale,
      DEFAULT_TEXTURE_SCALE
    );

    if (defined(value.texCoord) && defined(extension.texCoord)) {
      generatedMaterialValues[uniformName].texCoord = extension.texCoord;
    }
  }

  function generateTechnique$1(
    gltf,
    material,
    materialIndex,
    generatedMaterialValues,
    primitiveByMaterial,
    options
  ) {
    var addBatchIdToGeneratedShaders = defaultValue(
      options.addBatchIdToGeneratedShaders,
      false
    );

    var techniquesWebgl = gltf.extensions.KHR_techniques_webgl;
    var techniques = techniquesWebgl.techniques;
    var shaders = techniquesWebgl.shaders;
    var programs = techniquesWebgl.programs;

    var useSpecGloss = isSpecularGlossinessMaterial(material);

    var uniformName;
    var parameterName;
    var value;
    var pbrMetallicRoughness = material.pbrMetallicRoughness;
    if (defined(pbrMetallicRoughness) && !useSpecGloss) {
      for (parameterName in pbrMetallicRoughness) {
        if (pbrMetallicRoughness.hasOwnProperty(parameterName)) {
          value = pbrMetallicRoughness[parameterName];
          uniformName = "u_" + parameterName;
          generatedMaterialValues[uniformName] = value;
          handleKHRTextureTransform(
            parameterName,
            value,
            generatedMaterialValues
          );
        }
      }
    }

    if (useSpecGloss) {
      var pbrSpecularGlossiness =
        material.extensions.KHR_materials_pbrSpecularGlossiness;
      for (parameterName in pbrSpecularGlossiness) {
        if (pbrSpecularGlossiness.hasOwnProperty(parameterName)) {
          value = pbrSpecularGlossiness[parameterName];
          uniformName = "u_" + parameterName;
          generatedMaterialValues[uniformName] = value;
          handleKHRTextureTransform(
            parameterName,
            value,
            generatedMaterialValues
          );
        }
      }
    }

    for (var additional in material) {
      if (
        material.hasOwnProperty(additional) &&
        (additional.indexOf("Texture") >= 0 || additional.indexOf("Factor") >= 0)
      ) {
        value = material[additional];
        uniformName = "u_" + additional;
        generatedMaterialValues[uniformName] = value;
        handleKHRTextureTransform(additional, value, generatedMaterialValues);
      }
    }

    var vertexShader = "precision highp float;\n";
    var fragmentShader = "precision highp float;\n";

    var skin;
    if (defined(gltf.skins)) {
      skin = gltf.skins[0];
    }
    var joints = defined(skin) ? skin.joints : [];
    var jointCount = joints.length;

    var primitiveInfo = primitiveByMaterial[materialIndex];

    var skinningInfo;
    var hasSkinning = false;
    var hasVertexColors = false;
    var hasMorphTargets = false;
    var hasNormals = false;
    var hasTangents = false;
    var hasTexCoords = false;
    var hasTexCoord1 = false;
    var hasOutline = false;
    var isUnlit = false;

    if (defined(primitiveInfo)) {
      skinningInfo = primitiveInfo.skinning;
      hasSkinning = skinningInfo.skinned && joints.length > 0;
      hasVertexColors = primitiveInfo.hasVertexColors;
      hasMorphTargets = primitiveInfo.hasMorphTargets;
      hasNormals = primitiveInfo.hasNormals;
      hasTangents = primitiveInfo.hasTangents;
      hasTexCoords = primitiveInfo.hasTexCoords;
      hasTexCoord1 = primitiveInfo.hasTexCoord1;
      hasOutline = primitiveInfo.hasOutline;
    }

    var morphTargets;
    if (hasMorphTargets) {
      ForEach.mesh(gltf, function (mesh) {
        ForEach.meshPrimitive(mesh, function (primitive) {
          if (primitive.material === materialIndex) {
            var targets = primitive.targets;
            if (defined(targets)) {
              morphTargets = targets;
            }
          }
        });
      });
    }

    // Add techniques
    var techniqueUniforms = {
      // Add matrices
      u_modelViewMatrix: {
        semantic: hasExtension(gltf, "CESIUM_RTC")
          ? "CESIUM_RTC_MODELVIEW"
          : "MODELVIEW",
        type: WebGLConstants$1.FLOAT_MAT4,
      },
      u_projectionMatrix: {
        semantic: "PROJECTION",
        type: WebGLConstants$1.FLOAT_MAT4,
      },
    };

    if (
      defined(material.extensions) &&
      defined(material.extensions.KHR_materials_unlit)
    ) {
      isUnlit = true;
      hasNormals = false;
      hasTangents = false;
    }

    if (hasNormals) {
      techniqueUniforms.u_normalMatrix = {
        semantic: "MODELVIEWINVERSETRANSPOSE",
        type: WebGLConstants$1.FLOAT_MAT3,
      };
    }

    if (hasSkinning) {
      techniqueUniforms.u_jointMatrix = {
        count: jointCount,
        semantic: "JOINTMATRIX",
        type: WebGLConstants$1.FLOAT_MAT4,
      };
    }

    if (hasMorphTargets) {
      techniqueUniforms.u_morphWeights = {
        count: morphTargets.length,
        semantic: "MORPHWEIGHTS",
        type: WebGLConstants$1.FLOAT,
      };
    }

    var alphaMode = material.alphaMode;
    if (defined(alphaMode) && alphaMode === "MASK") {
      techniqueUniforms.u_alphaCutoff = {
        semantic: "ALPHACUTOFF",
        type: WebGLConstants$1.FLOAT,
      };
    }

    // Add material values
    for (uniformName in generatedMaterialValues) {
      if (generatedMaterialValues.hasOwnProperty(uniformName)) {
        techniqueUniforms[uniformName] = {
          type: getPBRValueType(uniformName),
        };
      }
    }

    var baseColorUniform = defaultValue(
      techniqueUniforms.u_baseColorTexture,
      techniqueUniforms.u_baseColorFactor
    );
    if (defined(baseColorUniform)) {
      baseColorUniform.semantic = "_3DTILESDIFFUSE";
    }

    // Add uniforms to shaders
    for (uniformName in techniqueUniforms) {
      if (techniqueUniforms.hasOwnProperty(uniformName)) {
        var uniform = techniqueUniforms[uniformName];
        var arraySize = defined(uniform.count) ? "[" + uniform.count + "]" : "";
        if (
          (uniform.type !== WebGLConstants$1.FLOAT_MAT3 &&
            uniform.type !== WebGLConstants$1.FLOAT_MAT4 &&
            uniformName !== "u_morphWeights") ||
          uniform.useInFragment
        ) {
          fragmentShader +=
            "uniform " +
            webGLConstantToGlslType(uniform.type) +
            " " +
            uniformName +
            arraySize +
            ";\n";
          delete uniform.useInFragment;
        } else {
          vertexShader +=
            "uniform " +
            webGLConstantToGlslType(uniform.type) +
            " " +
            uniformName +
            arraySize +
            ";\n";
        }
      }
    }

    if (hasOutline) {
      fragmentShader += "uniform sampler2D u_outlineTexture;\n";
    }

    // Add attributes with semantics
    var vertexShaderMain = "";
    if (hasSkinning) {
      vertexShaderMain +=
        "    mat4 skinMatrix =\n" +
        "        a_weight.x * u_jointMatrix[int(a_joint.x)] +\n" +
        "        a_weight.y * u_jointMatrix[int(a_joint.y)] +\n" +
        "        a_weight.z * u_jointMatrix[int(a_joint.z)] +\n" +
        "        a_weight.w * u_jointMatrix[int(a_joint.w)];\n";
    }

    // Add position always
    var techniqueAttributes = {
      a_position: {
        semantic: "POSITION",
      },
    };

    if (hasOutline) {
      techniqueAttributes.a_outlineCoordinates = {
        semantic: "_OUTLINE_COORDINATES",
      };
    }

    vertexShader += "attribute vec3 a_position;\n";
    if (hasNormals) {
      vertexShader += "varying vec3 v_positionEC;\n";
    }
    if (hasOutline) {
      vertexShader += "attribute vec3 a_outlineCoordinates;\n";
      vertexShader += "varying vec3 v_outlineCoordinates;\n";
    }

    // Morph Target Weighting
    vertexShaderMain += "    vec3 weightedPosition = a_position;\n";
    if (hasNormals) {
      vertexShaderMain += "    vec3 weightedNormal = a_normal;\n";
    }
    if (hasTangents) {
      vertexShaderMain += "    vec4 weightedTangent = a_tangent;\n";
    }
    if (hasMorphTargets) {
      for (var k = 0; k < morphTargets.length; k++) {
        var targetAttributes = morphTargets[k];
        for (var targetAttribute in targetAttributes) {
          if (
            targetAttributes.hasOwnProperty(targetAttribute) &&
            targetAttribute !== "extras"
          ) {
            var attributeName = "a_" + targetAttribute + "_" + k;
            techniqueAttributes[attributeName] = {
              semantic: targetAttribute + "_" + k,
            };
            vertexShader += "attribute vec3 " + attributeName + ";\n";
            if (targetAttribute === "POSITION") {
              vertexShaderMain +=
                "    weightedPosition += u_morphWeights[" +
                k +
                "] * " +
                attributeName +
                ";\n";
            } else if (targetAttribute === "NORMAL") {
              vertexShaderMain +=
                "    weightedNormal += u_morphWeights[" +
                k +
                "] * " +
                attributeName +
                ";\n";
            } else if (hasTangents && targetAttribute === "TANGENT") {
              vertexShaderMain +=
                "    weightedTangent.xyz += u_morphWeights[" +
                k +
                "] * " +
                attributeName +
                ";\n";
            }
          }
        }
      }
    }

    // Final position computation
    if (hasSkinning) {
      vertexShaderMain +=
        "    vec4 position = skinMatrix * vec4(weightedPosition, 1.0);\n";
    } else {
      vertexShaderMain += "    vec4 position = vec4(weightedPosition, 1.0);\n";
    }
    vertexShaderMain += "    position = u_modelViewMatrix * position;\n";
    if (hasNormals) {
      vertexShaderMain += "    v_positionEC = position.xyz;\n";
    }
    vertexShaderMain += "    gl_Position = u_projectionMatrix * position;\n";

    if (hasOutline) {
      vertexShaderMain += "    v_outlineCoordinates = a_outlineCoordinates;\n";
    }

    // Final normal computation
    if (hasNormals) {
      techniqueAttributes.a_normal = {
        semantic: "NORMAL",
      };
      vertexShader += "attribute vec3 a_normal;\n";
      vertexShader += "varying vec3 v_normal;\n";
      if (hasSkinning) {
        vertexShaderMain +=
          "    v_normal = u_normalMatrix * mat3(skinMatrix) * weightedNormal;\n";
      } else {
        vertexShaderMain += "    v_normal = u_normalMatrix * weightedNormal;\n";
      }

      fragmentShader += "varying vec3 v_normal;\n";
      fragmentShader += "varying vec3 v_positionEC;\n";
    }

    // Read tangents if available
    if (hasTangents) {
      techniqueAttributes.a_tangent = {
        semantic: "TANGENT",
      };
      vertexShader += "attribute vec4 a_tangent;\n";
      vertexShader += "varying vec4 v_tangent;\n";
      vertexShaderMain +=
        "    v_tangent.xyz = u_normalMatrix * weightedTangent.xyz;\n";
      vertexShaderMain += "    v_tangent.w = weightedTangent.w;\n";

      fragmentShader += "varying vec4 v_tangent;\n";
    }

    if (hasOutline) {
      fragmentShader += "varying vec3 v_outlineCoordinates;\n";
    }

    var fragmentShaderMain = "";

    // Add texture coordinates if the material uses them
    var v_texCoord;
    var normalTexCoord;
    var baseColorTexCoord;
    var specularGlossinessTexCoord;
    var diffuseTexCoord;
    var metallicRoughnessTexCoord;
    var occlusionTexCoord;
    var emissiveTexCoord;

    if (hasTexCoords) {
      techniqueAttributes.a_texcoord_0 = {
        semantic: "TEXCOORD_0",
      };

      v_texCoord = "v_texcoord_0";
      vertexShader += "attribute vec2 a_texcoord_0;\n";
      vertexShader += "varying vec2 " + v_texCoord + ";\n";
      vertexShaderMain += "    " + v_texCoord + " = a_texcoord_0;\n";

      fragmentShader += "varying vec2 " + v_texCoord + ";\n";

      if (hasTexCoord1) {
        techniqueAttributes.a_texcoord_1 = {
          semantic: "TEXCOORD_1",
        };

        var v_texCoord1 = v_texCoord.replace("0", "1");
        vertexShader += "attribute vec2 a_texcoord_1;\n";
        vertexShader += "varying vec2 " + v_texCoord1 + ";\n";
        vertexShaderMain += "    " + v_texCoord1 + " = a_texcoord_1;\n";

        fragmentShader += "varying vec2 " + v_texCoord1 + ";\n";
      }

      var result = {
        fragmentShaderMain: fragmentShaderMain,
      };
      normalTexCoord = addTextureCoordinates(
        gltf,
        "u_normalTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );
      baseColorTexCoord = addTextureCoordinates(
        gltf,
        "u_baseColorTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );
      specularGlossinessTexCoord = addTextureCoordinates(
        gltf,
        "u_specularGlossinessTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );
      diffuseTexCoord = addTextureCoordinates(
        gltf,
        "u_diffuseTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );
      metallicRoughnessTexCoord = addTextureCoordinates(
        gltf,
        "u_metallicRoughnessTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );
      occlusionTexCoord = addTextureCoordinates(
        gltf,
        "u_occlusionTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );
      emissiveTexCoord = addTextureCoordinates(
        gltf,
        "u_emissiveTexture",
        generatedMaterialValues,
        v_texCoord,
        result
      );

      fragmentShaderMain = result.fragmentShaderMain;
    }

    // Add skinning information if available
    if (hasSkinning) {
      techniqueAttributes.a_joint = {
        semantic: "JOINTS_0",
      };
      techniqueAttributes.a_weight = {
        semantic: "WEIGHTS_0",
      };

      vertexShader += "attribute vec4 a_joint;\n";
      vertexShader += "attribute vec4 a_weight;\n";
    }

    if (hasVertexColors) {
      techniqueAttributes.a_vertexColor = {
        semantic: "COLOR_0",
      };
      vertexShader += "attribute vec4 a_vertexColor;\n";
      vertexShader += "varying vec4 v_vertexColor;\n";
      vertexShaderMain += "  v_vertexColor = a_vertexColor;\n";
      fragmentShader += "varying vec4 v_vertexColor;\n";
    }

    if (addBatchIdToGeneratedShaders) {
      techniqueAttributes.a_batchId = {
        semantic: "_BATCHID",
      };
      vertexShader += "attribute float a_batchId;\n";
    }

    vertexShader += "void main(void) \n{\n";
    vertexShader += vertexShaderMain;
    vertexShader += "}\n";

    // Fragment shader lighting
    if (hasNormals) {
      fragmentShader += "const float M_PI = 3.141592653589793;\n";

      fragmentShader +=
        "vec3 lambertianDiffuse(vec3 diffuseColor) \n" +
        "{\n" +
        "    return diffuseColor / M_PI;\n" +
        "}\n\n";

      fragmentShader +=
        "vec3 fresnelSchlick2(vec3 f0, vec3 f90, float VdotH) \n" +
        "{\n" +
        "    return f0 + (f90 - f0) * pow(clamp(1.0 - VdotH, 0.0, 1.0), 5.0);\n" +
        "}\n\n";

      fragmentShader +=
        "vec3 fresnelSchlick(float metalness, float VdotH) \n" +
        "{\n" +
        "    return metalness + (vec3(1.0) - metalness) * pow(1.0 - VdotH, 5.0);\n" +
        "}\n\n";

      fragmentShader +=
        "float smithVisibilityG1(float NdotV, float roughness) \n" +
        "{\n" +
        "    float k = (roughness + 1.0) * (roughness + 1.0) / 8.0;\n" +
        "    return NdotV / (NdotV * (1.0 - k) + k);\n" +
        "}\n\n";

      fragmentShader +=
        "float smithVisibilityGGX(float roughness, float NdotL, float NdotV) \n" +
        "{\n" +
        "    return smithVisibilityG1(NdotL, roughness) * smithVisibilityG1(NdotV, roughness);\n" +
        "}\n\n";

      fragmentShader +=
        "float GGX(float roughness, float NdotH) \n" +
        "{\n" +
        "    float roughnessSquared = roughness * roughness;\n" +
        "    float f = (NdotH * roughnessSquared - NdotH) * NdotH + 1.0;\n" +
        "    return roughnessSquared / (M_PI * f * f);\n" +
        "}\n\n";
    }

    fragmentShader +=
      "vec3 SRGBtoLINEAR3(vec3 srgbIn) \n" +
      "{\n" +
      "    return pow(srgbIn, vec3(2.2));\n" +
      "}\n\n";

    fragmentShader +=
      "vec4 SRGBtoLINEAR4(vec4 srgbIn) \n" +
      "{\n" +
      "    vec3 linearOut = pow(srgbIn.rgb, vec3(2.2));\n" +
      "    return vec4(linearOut, srgbIn.a);\n" +
      "}\n\n";

    fragmentShader +=
      "vec3 applyTonemapping(vec3 linearIn) \n" +
      "{\n" +
      "#ifndef HDR \n" +
      "    return czm_acesTonemapping(linearIn);\n" +
      "#else \n" +
      "    return linearIn;\n" +
      "#endif \n" +
      "}\n\n";

    fragmentShader +=
      "vec3 LINEARtoSRGB(vec3 linearIn) \n" +
      "{\n" +
      "#ifndef HDR \n" +
      "    return pow(linearIn, vec3(1.0/2.2));\n" +
      "#else \n" +
      "    return linearIn;\n" +
      "#endif \n" +
      "}\n\n";

    fragmentShader +=
      "vec2 computeTexCoord(vec2 texCoords, vec2 offset, float rotation, vec2 scale) \n" +
      "{\n" +
      "    rotation = -rotation; \n" +
      "    mat3 transform = mat3(\n" +
      "        cos(rotation) * scale.x, sin(rotation) * scale.x, 0.0, \n" +
      "       -sin(rotation) * scale.y, cos(rotation) * scale.y, 0.0, \n" +
      "        offset.x, offset.y, 1.0); \n" +
      "    vec2 transformedTexCoords = (transform * vec3(fract(texCoords), 1.0)).xy; \n" +
      "    return transformedTexCoords; \n" +
      "}\n\n";

    fragmentShader += "#ifdef USE_IBL_LIGHTING \n";
    fragmentShader += "uniform vec2 gltf_iblFactor; \n";
    fragmentShader += "#endif \n";
    fragmentShader += "#ifdef USE_CUSTOM_LIGHT_COLOR \n";
    fragmentShader += "uniform vec3 gltf_lightColor; \n";
    fragmentShader += "#endif \n";

    fragmentShader += "void main(void) \n{\n";
    fragmentShader += fragmentShaderMain;

    // Add normal mapping to fragment shader
    if (hasNormals) {
      fragmentShader += "    vec3 ng = normalize(v_normal);\n";
      fragmentShader +=
        "    vec3 positionWC = vec3(czm_inverseView * vec4(v_positionEC, 1.0));\n";
      if (defined(generatedMaterialValues.u_normalTexture)) {
        if (hasTangents) {
          // Read tangents from varying
          fragmentShader += "    vec3 t = normalize(v_tangent.xyz);\n";
          fragmentShader +=
            "    vec3 b = normalize(cross(ng, t) * v_tangent.w);\n";
          fragmentShader += "    mat3 tbn = mat3(t, b, ng);\n";
          fragmentShader +=
            "    vec3 n = texture2D(u_normalTexture, " +
            normalTexCoord +
            ").rgb;\n";
          fragmentShader += "    n = normalize(tbn * (2.0 * n - 1.0));\n";
        } else {
          // Add standard derivatives extension
          fragmentShader =
            "#ifdef GL_OES_standard_derivatives\n" +
            "#extension GL_OES_standard_derivatives : enable\n" +
            "#endif\n" +
            fragmentShader;
          // Compute tangents
          fragmentShader += "#ifdef GL_OES_standard_derivatives\n";
          fragmentShader += "    vec3 pos_dx = dFdx(v_positionEC);\n";
          fragmentShader += "    vec3 pos_dy = dFdy(v_positionEC);\n";
          fragmentShader +=
            "    vec3 tex_dx = dFdx(vec3(" + normalTexCoord + ",0.0));\n";
          fragmentShader +=
            "    vec3 tex_dy = dFdy(vec3(" + normalTexCoord + ",0.0));\n";
          fragmentShader +=
            "    vec3 t = (tex_dy.t * pos_dx - tex_dx.t * pos_dy) / (tex_dx.s * tex_dy.t - tex_dy.s * tex_dx.t);\n";
          fragmentShader += "    t = normalize(t - ng * dot(ng, t));\n";
          fragmentShader += "    vec3 b = normalize(cross(ng, t));\n";
          fragmentShader += "    mat3 tbn = mat3(t, b, ng);\n";
          fragmentShader +=
            "    vec3 n = texture2D(u_normalTexture, " +
            normalTexCoord +
            ").rgb;\n";
          fragmentShader += "    n = normalize(tbn * (2.0 * n - 1.0));\n";
          fragmentShader += "#else\n";
          fragmentShader += "    vec3 n = ng;\n";
          fragmentShader += "#endif\n";
        }
      } else {
        fragmentShader += "    vec3 n = ng;\n";
      }
      if (material.doubleSided) {
        fragmentShader += "    if (czm_backFacing())\n";
        fragmentShader += "    {\n";
        fragmentShader += "        n = -n;\n";
        fragmentShader += "    }\n";
      }
    }

    // Add base color to fragment shader
    if (defined(generatedMaterialValues.u_baseColorTexture)) {
      fragmentShader +=
        "    vec4 baseColorWithAlpha = SRGBtoLINEAR4(texture2D(u_baseColorTexture, " +
        baseColorTexCoord +
        "));\n";
      if (defined(generatedMaterialValues.u_baseColorFactor)) {
        fragmentShader += "    baseColorWithAlpha *= u_baseColorFactor;\n";
      }
    } else if (defined(generatedMaterialValues.u_baseColorFactor)) {
      fragmentShader += "    vec4 baseColorWithAlpha = u_baseColorFactor;\n";
    } else {
      fragmentShader += "    vec4 baseColorWithAlpha = vec4(1.0);\n";
    }

    if (hasVertexColors) {
      fragmentShader += "    baseColorWithAlpha *= v_vertexColor;\n";
    }

    fragmentShader += "    vec3 baseColor = baseColorWithAlpha.rgb;\n";

    if (hasNormals) {
      if (useSpecGloss) {
        if (defined(generatedMaterialValues.u_specularGlossinessTexture)) {
          fragmentShader +=
            "    vec4 specularGlossiness = SRGBtoLINEAR4(texture2D(u_specularGlossinessTexture, " +
            specularGlossinessTexCoord +
            "));\n";
          fragmentShader += "    vec3 specular = specularGlossiness.rgb;\n";
          fragmentShader += "    float glossiness = specularGlossiness.a;\n";
          if (defined(generatedMaterialValues.u_specularFactor)) {
            fragmentShader += "    specular *= u_specularFactor;\n";
          }
          if (defined(generatedMaterialValues.u_glossinessFactor)) {
            fragmentShader += "    glossiness *= u_glossinessFactor;\n";
          }
        } else {
          if (defined(generatedMaterialValues.u_specularFactor)) {
            fragmentShader +=
              "    vec3 specular = clamp(u_specularFactor, vec3(0.0), vec3(1.0));\n";
          } else {
            fragmentShader += "    vec3 specular = vec3(1.0);\n";
          }
          if (defined(generatedMaterialValues.u_glossinessFactor)) {
            fragmentShader +=
              "    float glossiness = clamp(u_glossinessFactor, 0.0, 1.0);\n";
          } else {
            fragmentShader += "    float glossiness = 1.0;\n";
          }
        }
        if (defined(generatedMaterialValues.u_diffuseTexture)) {
          fragmentShader +=
            "    vec4 diffuse = SRGBtoLINEAR4(texture2D(u_diffuseTexture, " +
            diffuseTexCoord +
            "));\n";
          if (defined(generatedMaterialValues.u_diffuseFactor)) {
            fragmentShader += "    diffuse *= u_diffuseFactor;\n";
          }
        } else if (defined(generatedMaterialValues.u_diffuseFactor)) {
          fragmentShader +=
            "    vec4 diffuse = clamp(u_diffuseFactor, vec4(0.0), vec4(1.0));\n";
        } else {
          fragmentShader += "    vec4 diffuse = vec4(1.0);\n";
        }
      } else if (defined(generatedMaterialValues.u_metallicRoughnessTexture)) {
        fragmentShader +=
          "    vec3 metallicRoughness = texture2D(u_metallicRoughnessTexture, " +
          metallicRoughnessTexCoord +
          ").rgb;\n";
        fragmentShader +=
          "    float metalness = clamp(metallicRoughness.b, 0.0, 1.0);\n";
        fragmentShader +=
          "    float roughness = clamp(metallicRoughness.g, 0.04, 1.0);\n";
        if (defined(generatedMaterialValues.u_metallicFactor)) {
          fragmentShader += "    metalness *= u_metallicFactor;\n";
        }
        if (defined(generatedMaterialValues.u_roughnessFactor)) {
          fragmentShader += "    roughness *= u_roughnessFactor;\n";
        }
      } else {
        if (defined(generatedMaterialValues.u_metallicFactor)) {
          fragmentShader +=
            "    float metalness = clamp(u_metallicFactor, 0.0, 1.0);\n";
        } else {
          fragmentShader += "    float metalness = 1.0;\n";
        }
        if (defined(generatedMaterialValues.u_roughnessFactor)) {
          fragmentShader +=
            "    float roughness = clamp(u_roughnessFactor, 0.04, 1.0);\n";
        } else {
          fragmentShader += "    float roughness = 1.0;\n";
        }
      }

      fragmentShader += "    vec3 v = -normalize(v_positionEC);\n";

      // Generate fragment shader's lighting block
      fragmentShader += "#ifndef USE_CUSTOM_LIGHT_COLOR \n";
      fragmentShader += "    vec3 lightColorHdr = czm_lightColorHdr;\n";
      fragmentShader += "#else \n";
      fragmentShader += "    vec3 lightColorHdr = gltf_lightColor;\n";
      fragmentShader += "#endif \n";
      fragmentShader += "    vec3 l = normalize(czm_lightDirectionEC);\n";
      fragmentShader += "    vec3 h = normalize(v + l);\n";
      fragmentShader += "    float NdotL = clamp(dot(n, l), 0.001, 1.0);\n";
      fragmentShader += "    float NdotV = abs(dot(n, v)) + 0.001;\n";
      fragmentShader += "    float NdotH = clamp(dot(n, h), 0.0, 1.0);\n";
      fragmentShader += "    float LdotH = clamp(dot(l, h), 0.0, 1.0);\n";
      fragmentShader += "    float VdotH = clamp(dot(v, h), 0.0, 1.0);\n";
      fragmentShader += "    vec3 f0 = vec3(0.04);\n";
      // Whether the material uses metallic-roughness or specular-glossiness changes how the BRDF inputs are computed.
      // It does not change the implementation of the BRDF itself.
      if (useSpecGloss) {
        fragmentShader += "    float roughness = 1.0 - glossiness;\n";
        fragmentShader +=
          "    vec3 diffuseColor = diffuse.rgb * (1.0 - max(max(specular.r, specular.g), specular.b));\n";
        fragmentShader += "    vec3 specularColor = specular;\n";
      } else {
        fragmentShader +=
          "    vec3 diffuseColor = baseColor * (1.0 - metalness) * (1.0 - f0);\n";
        fragmentShader +=
          "    vec3 specularColor = mix(f0, baseColor, metalness);\n";
      }

      fragmentShader += "    float alpha = roughness * roughness;\n";
      fragmentShader +=
        "    float reflectance = max(max(specularColor.r, specularColor.g), specularColor.b);\n";
      fragmentShader +=
        "    vec3 r90 = vec3(clamp(reflectance * 25.0, 0.0, 1.0));\n";
      fragmentShader += "    vec3 r0 = specularColor.rgb;\n";

      fragmentShader += "    vec3 F = fresnelSchlick2(r0, r90, VdotH);\n";
      fragmentShader +=
        "    float G = smithVisibilityGGX(alpha, NdotL, NdotV);\n";
      fragmentShader += "    float D = GGX(alpha, NdotH);\n";

      fragmentShader +=
        "    vec3 diffuseContribution = (1.0 - F) * lambertianDiffuse(diffuseColor);\n";
      fragmentShader +=
        "    vec3 specularContribution = F * G * D / (4.0 * NdotL * NdotV);\n";
      fragmentShader +=
        "    vec3 color = NdotL * lightColorHdr * (diffuseContribution + specularContribution);\n";

      // Use the procedural IBL if there are no environment maps
      fragmentShader +=
        "#if defined(USE_IBL_LIGHTING) && !defined(DIFFUSE_IBL) && !defined(SPECULAR_IBL) \n";

      fragmentShader +=
        "    vec3 r = normalize(czm_inverseViewRotation * normalize(reflect(v, n)));\n";
      // Figure out if the reflection vector hits the ellipsoid
      fragmentShader += "    float vertexRadius = length(positionWC);\n";
      fragmentShader +=
        "    float horizonDotNadir = 1.0 - min(1.0, czm_ellipsoidRadii.x / vertexRadius);\n";
      fragmentShader +=
        "    float reflectionDotNadir = dot(r, normalize(positionWC));\n";
      // Flipping the X vector is a cheap way to get the inverse of czm_temeToPseudoFixed, since that's a rotation about Z.
      fragmentShader += "    r.x = -r.x;\n";
      fragmentShader += "    r = -normalize(czm_temeToPseudoFixed * r);\n";
      fragmentShader += "    r.x = -r.x;\n";

      fragmentShader += "    float inverseRoughness = 1.04 - roughness;\n";
      fragmentShader += "    inverseRoughness *= inverseRoughness;\n";
      fragmentShader +=
        "    vec3 sceneSkyBox = textureCube(czm_environmentMap, r).rgb * inverseRoughness;\n";

      fragmentShader += "    float atmosphereHeight = 0.05;\n";
      fragmentShader +=
        "    float blendRegionSize = 0.1 * ((1.0 - inverseRoughness) * 8.0 + 1.1 - horizonDotNadir);\n";
      fragmentShader += "    float blendRegionOffset = roughness * -1.0;\n";
      fragmentShader +=
        "    float farAboveHorizon = clamp(horizonDotNadir - blendRegionSize * 0.5 + blendRegionOffset, 1.0e-10 - blendRegionSize, 0.99999);\n";
      fragmentShader +=
        "    float aroundHorizon = clamp(horizonDotNadir + blendRegionSize * 0.5, 1.0e-10 - blendRegionSize, 0.99999);\n";
      fragmentShader +=
        "    float farBelowHorizon = clamp(horizonDotNadir + blendRegionSize * 1.5, 1.0e-10 - blendRegionSize, 0.99999);\n";
      fragmentShader +=
        "    float smoothstepHeight = smoothstep(0.0, atmosphereHeight, horizonDotNadir);\n";

      fragmentShader +=
        "    vec3 belowHorizonColor = mix(vec3(0.1, 0.15, 0.25), vec3(0.4, 0.7, 0.9), smoothstepHeight);\n";
      fragmentShader += "    vec3 nadirColor = belowHorizonColor * 0.5;\n";
      fragmentShader +=
        "    vec3 aboveHorizonColor = mix(vec3(0.9, 1.0, 1.2), belowHorizonColor, roughness * 0.5);\n";
      fragmentShader +=
        "    vec3 blueSkyColor = mix(vec3(0.18, 0.26, 0.48), aboveHorizonColor, reflectionDotNadir * inverseRoughness * 0.5 + 0.75);\n";
      fragmentShader +=
        "    vec3 zenithColor = mix(blueSkyColor, sceneSkyBox, smoothstepHeight);\n";

      fragmentShader += "    vec3 blueSkyDiffuseColor = vec3(0.7, 0.85, 0.9);\n";
      fragmentShader +=
        "    float diffuseIrradianceFromEarth = (1.0 - horizonDotNadir) * (reflectionDotNadir * 0.25 + 0.75) * smoothstepHeight;\n";
      fragmentShader +=
        "    float diffuseIrradianceFromSky = (1.0 - smoothstepHeight) * (1.0 - (reflectionDotNadir * 0.25 + 0.25));\n";
      fragmentShader +=
        "    vec3 diffuseIrradiance = blueSkyDiffuseColor * clamp(diffuseIrradianceFromEarth + diffuseIrradianceFromSky, 0.0, 1.0);\n";

      fragmentShader +=
        "    float notDistantRough = (1.0 - horizonDotNadir * roughness * 0.8);\n";
      fragmentShader +=
        "    vec3 specularIrradiance = mix(zenithColor, aboveHorizonColor, smoothstep(farAboveHorizon, aroundHorizon, reflectionDotNadir) * notDistantRough);\n";
      fragmentShader +=
        "    specularIrradiance = mix(specularIrradiance, belowHorizonColor, smoothstep(aroundHorizon, farBelowHorizon, reflectionDotNadir) * inverseRoughness);\n";
      fragmentShader +=
        "    specularIrradiance = mix(specularIrradiance, nadirColor, smoothstep(farBelowHorizon, 1.0, reflectionDotNadir) * inverseRoughness);\n";

      // Luminance model from page 40 of http://silviojemma.com/public/papers/lighting/spherical-harmonic-lighting.pdf
      fragmentShader += "#ifdef USE_SUN_LUMINANCE \n";
      // Angle between sun and zenith
      fragmentShader +=
        "    float LdotZenith = clamp(dot(normalize(czm_inverseViewRotation * l), normalize(positionWC * -1.0)), 0.001, 1.0);\n";
      fragmentShader += "    float S = acos(LdotZenith);\n";
      // Angle between zenith and current pixel
      fragmentShader +=
        "    float NdotZenith = clamp(dot(normalize(czm_inverseViewRotation * n), normalize(positionWC * -1.0)), 0.001, 1.0);\n";
      // Angle between sun and current pixel
      fragmentShader += "    float gamma = acos(NdotL);\n";
      fragmentShader +=
        "    float numerator = ((0.91 + 10.0 * exp(-3.0 * gamma) + 0.45 * pow(NdotL, 2.0)) * (1.0 - exp(-0.32 / NdotZenith)));\n";
      fragmentShader +=
        "    float denominator = (0.91 + 10.0 * exp(-3.0 * S) + 0.45 * pow(LdotZenith,2.0)) * (1.0 - exp(-0.32));\n";
      fragmentShader +=
        "    float luminance = gltf_luminanceAtZenith * (numerator / denominator);\n";
      fragmentShader += "#endif \n";

      fragmentShader +=
        "    vec2 brdfLut = texture2D(czm_brdfLut, vec2(NdotV, roughness)).rg;\n";
      fragmentShader +=
        "    vec3 IBLColor = (diffuseIrradiance * diffuseColor * gltf_iblFactor.x) + (specularIrradiance * SRGBtoLINEAR3(specularColor * brdfLut.x + brdfLut.y) * gltf_iblFactor.y);\n";

      fragmentShader +=
        "    float maximumComponent = max(max(lightColorHdr.x, lightColorHdr.y), lightColorHdr.z);\n";
      fragmentShader +=
        "    vec3 lightColor = lightColorHdr / max(maximumComponent, 1.0);\n";
      fragmentShader += "    IBLColor *= lightColor;\n";

      fragmentShader += "#ifdef USE_SUN_LUMINANCE \n";
      fragmentShader += "    color += IBLColor * luminance;\n";
      fragmentShader += "#else \n";
      fragmentShader += "    color += IBLColor; \n";
      fragmentShader += "#endif \n";

      // Environment maps were provided, use them for IBL
      fragmentShader += "#elif defined(DIFFUSE_IBL) || defined(SPECULAR_IBL) \n";

      fragmentShader +=
        "    mat3 fixedToENU = mat3(gltf_clippingPlanesMatrix[0][0], gltf_clippingPlanesMatrix[1][0], gltf_clippingPlanesMatrix[2][0], \n";
      fragmentShader +=
        "                           gltf_clippingPlanesMatrix[0][1], gltf_clippingPlanesMatrix[1][1], gltf_clippingPlanesMatrix[2][1], \n";
      fragmentShader +=
        "                           gltf_clippingPlanesMatrix[0][2], gltf_clippingPlanesMatrix[1][2], gltf_clippingPlanesMatrix[2][2]); \n";
      fragmentShader +=
        "    const mat3 yUpToZUp = mat3(-1.0, 0.0, 0.0, 0.0, 0.0, -1.0, 0.0, 1.0, 0.0); \n";
      fragmentShader +=
        "    vec3 cubeDir = normalize(yUpToZUp * fixedToENU * normalize(reflect(-v, n))); \n";

      fragmentShader += "#ifdef DIFFUSE_IBL \n";
      fragmentShader += "#ifdef CUSTOM_SPHERICAL_HARMONICS \n";
      fragmentShader +=
        "    vec3 diffuseIrradiance = czm_sphericalHarmonics(cubeDir, gltf_sphericalHarmonicCoefficients); \n";
      fragmentShader += "#else \n";
      fragmentShader +=
        "    vec3 diffuseIrradiance = czm_sphericalHarmonics(cubeDir, czm_sphericalHarmonicCoefficients); \n";
      fragmentShader += "#endif \n";
      fragmentShader += "#else \n";
      fragmentShader += "    vec3 diffuseIrradiance = vec3(0.0); \n";
      fragmentShader += "#endif \n";

      fragmentShader += "#ifdef SPECULAR_IBL \n";
      fragmentShader +=
        "    vec2 brdfLut = texture2D(czm_brdfLut, vec2(NdotV, roughness)).rg;\n";
      fragmentShader += "#ifdef CUSTOM_SPECULAR_IBL \n";
      fragmentShader +=
        "    vec3 specularIBL = czm_sampleOctahedralProjection(gltf_specularMap, gltf_specularMapSize, cubeDir,  roughness * gltf_maxSpecularLOD, gltf_maxSpecularLOD);\n";
      fragmentShader += "#else \n";
      fragmentShader +=
        "    vec3 specularIBL = czm_sampleOctahedralProjection(czm_specularEnvironmentMaps, czm_specularEnvironmentMapSize, cubeDir,  roughness * czm_specularEnvironmentMapsMaximumLOD, czm_specularEnvironmentMapsMaximumLOD);\n";
      fragmentShader += "#endif \n";
      fragmentShader += "    specularIBL *= F * brdfLut.x + brdfLut.y;\n";
      fragmentShader += "#else \n";
      fragmentShader += "    vec3 specularIBL = vec3(0.0); \n";
      fragmentShader += "#endif \n";

      fragmentShader +=
        "    color += diffuseIrradiance * diffuseColor + specularColor * specularIBL;\n";

      fragmentShader += "#endif \n";
    } else {
      fragmentShader += "    vec3 color = baseColor;\n";
    }

    // Ignore occlusion and emissive when unlit
    if (!isUnlit) {
      if (defined(generatedMaterialValues.u_occlusionTexture)) {
        fragmentShader +=
          "    color *= texture2D(u_occlusionTexture, " +
          occlusionTexCoord +
          ").r;\n";
      }
      if (defined(generatedMaterialValues.u_emissiveTexture)) {
        fragmentShader +=
          "    vec3 emissive = SRGBtoLINEAR3(texture2D(u_emissiveTexture, " +
          emissiveTexCoord +
          ").rgb);\n";
        if (defined(generatedMaterialValues.u_emissiveFactor)) {
          fragmentShader += "    emissive *= u_emissiveFactor;\n";
        }
        fragmentShader += "    color += emissive;\n";
      } else if (defined(generatedMaterialValues.u_emissiveFactor)) {
        fragmentShader += "    color += u_emissiveFactor;\n";
      }
    }

    if (!isUnlit) {
      fragmentShader += "    color = applyTonemapping(color);\n";
    }

    fragmentShader += "    color = LINEARtoSRGB(color);\n";

    if (hasOutline) {
      fragmentShader += "    float outlineness = max(\n";
      fragmentShader +=
        "        texture2D(u_outlineTexture, vec2(v_outlineCoordinates.x, 0.5)).r,\n";
      fragmentShader += "        max(\n";
      fragmentShader +=
        "          texture2D(u_outlineTexture, vec2(v_outlineCoordinates.y, 0.5)).r,\n";
      fragmentShader +=
        "          texture2D(u_outlineTexture, vec2(v_outlineCoordinates.z, 0.5)).r));\n";
      fragmentShader +=
        "    color = mix(color, vec3(0.0, 0.0, 0.0), outlineness);\n";
    }

    if (defined(alphaMode)) {
      if (alphaMode === "MASK") {
        fragmentShader += "    if (baseColorWithAlpha.a < u_alphaCutoff) {\n";
        fragmentShader += "        discard;\n";
        fragmentShader += "    }\n";
        fragmentShader += "    gl_FragColor = vec4(color, 1.0);\n";
      } else if (alphaMode === "BLEND") {
        fragmentShader +=
          "    gl_FragColor = vec4(color, baseColorWithAlpha.a);\n";
      } else {
        fragmentShader += "    gl_FragColor = vec4(color, 1.0);\n";
      }
    } else {
      fragmentShader += "    gl_FragColor = vec4(color, 1.0);\n";
    }

    fragmentShader += "}\n";

    // Add shaders
    var vertexShaderId = addToArray(shaders, {
      type: WebGLConstants$1.VERTEX_SHADER,
      extras: {
        _pipeline: {
          source: vertexShader,
          extension: ".glsl",
        },
      },
    });

    var fragmentShaderId = addToArray(shaders, {
      type: WebGLConstants$1.FRAGMENT_SHADER,
      extras: {
        _pipeline: {
          source: fragmentShader,
          extension: ".glsl",
        },
      },
    });

    // Add program
    var programId = addToArray(programs, {
      fragmentShader: fragmentShaderId,
      vertexShader: vertexShaderId,
    });

    var techniqueId = addToArray(techniques, {
      attributes: techniqueAttributes,
      program: programId,
      uniforms: techniqueUniforms,
    });

    return techniqueId;
  }

  function getPBRValueType(paramName) {
    if (paramName.indexOf("Offset") !== -1) {
      return WebGLConstants$1.FLOAT_VEC2;
    } else if (paramName.indexOf("Rotation") !== -1) {
      return WebGLConstants$1.FLOAT;
    } else if (paramName.indexOf("Scale") !== -1) {
      return WebGLConstants$1.FLOAT_VEC2;
    } else if (paramName.indexOf("Texture") !== -1) {
      return WebGLConstants$1.SAMPLER_2D;
    }

    switch (paramName) {
      case "u_baseColorFactor":
        return WebGLConstants$1.FLOAT_VEC4;
      case "u_metallicFactor":
        return WebGLConstants$1.FLOAT;
      case "u_roughnessFactor":
        return WebGLConstants$1.FLOAT;
      case "u_emissiveFactor":
        return WebGLConstants$1.FLOAT_VEC3;
      // Specular Glossiness Types
      case "u_diffuseFactor":
        return WebGLConstants$1.FLOAT_VEC4;
      case "u_specularFactor":
        return WebGLConstants$1.FLOAT_VEC3;
      case "u_glossinessFactor":
        return WebGLConstants$1.FLOAT;
    }
  }

  /**
   * Describes a renderable batch of geometry.
   *
   * @alias Vector3DTileBatch
   * @constructor
   *
   * @param {Object} options An object with the following properties:
   * @param {Number} options.offset The offset of the batch into the indices buffer.
   * @param {Number} options.count The number of indices in the batch.
   * @param {Color} options.color The color of the geometry in the batch.
   * @param {Number[]} options.batchIds An array where each element is the batch id of the geometry in the batch.
   *
   * @private
   */
  function Vector3DTileBatch(options) {
    /**
     * The offset of the batch into the indices buffer.
     * @type {Number}
     */
    this.offset = options.offset;
    /**
     * The number of indices in the batch.
     * @type {Number}
     */
    this.count = options.count;
    /**
     * The color of the geometry in the batch.
     * @type {Color}
     */
    this.color = options.color;
    /**
     * An array where each element is the batch id of the geometry in the batch.
     * @type {Number[]}
     */
    this.batchIds = options.batchIds;
  }

  //This file is automatically rebuilt by the Cesium build process.
  var VectorTileVS = "attribute vec3 position;\n\
attribute float a_batchId;\n\
uniform mat4 u_modifiedModelViewProjection;\n\
void main()\n\
{\n\
gl_Position = czm_depthClamp(u_modifiedModelViewProjection * vec4(position, 1.0));\n\
}\n\
";

  //     JavaScript Expression Parser (JSEP) 0.3.1
  //     JSEP may be freely distributed under the MIT License
  //     http://jsep.from.so/

  var tmp$2 = {};

  /*global module: true, exports: true, console: true */
  (function (root) {
  	// Node Types
  	// ----------

  	// This is the full set of types that any JSEP node can be.
  	// Store them here to save space when minified
  	var COMPOUND = 'Compound',
  		IDENTIFIER = 'Identifier',
  		MEMBER_EXP = 'MemberExpression',
  		LITERAL = 'Literal',
  		THIS_EXP = 'ThisExpression',
  		CALL_EXP = 'CallExpression',
  		UNARY_EXP = 'UnaryExpression',
  		BINARY_EXP = 'BinaryExpression',
  		LOGICAL_EXP = 'LogicalExpression',
  		CONDITIONAL_EXP = 'ConditionalExpression',
  		ARRAY_EXP = 'ArrayExpression',

  		PERIOD_CODE = 46, // '.'
  		COMMA_CODE  = 44, // ','
  		SQUOTE_CODE = 39, // single quote
  		DQUOTE_CODE = 34, // double quotes
  		OPAREN_CODE = 40, // (
  		CPAREN_CODE = 41, // )
  		OBRACK_CODE = 91, // [
  		CBRACK_CODE = 93, // ]
  		QUMARK_CODE = 63, // ?
  		SEMCOL_CODE = 59, // ;
  		COLON_CODE  = 58, // :

  		throwError = function(message, index) {
  			var error = new Error(message + ' at character ' + index);
  			error.index = index;
  			error.description = message;
  			throw error;
  		},

  	// Operations
  	// ----------

  	// Set `t` to `true` to save space (when minified, not gzipped)
  		t = true,
  	// Use a quickly-accessible map to store all of the unary operators
  	// Values are set to `true` (it really doesn't matter)
  		unary_ops = {'-': t, '!': t, '~': t, '+': t},
  	// Also use a map for the binary operations but set their values to their
  	// binary precedence for quick reference:
  	// see [Order of operations](http://en.wikipedia.org/wiki/Order_of_operations#Programming_language)
  		binary_ops = {
  			'||': 1, '&&': 2, '|': 3,  '^': 4,  '&': 5,
  			'==': 6, '!=': 6, '===': 6, '!==': 6,
  			'<': 7,  '>': 7,  '<=': 7,  '>=': 7,
  			'<<':8,  '>>': 8, '>>>': 8,
  			'+': 9, '-': 9,
  			'*': 10, '/': 10, '%': 10
  		},
  	// Get return the longest key length of any object
  		getMaxKeyLen = function(obj) {
  			var max_len = 0, len;
  			for(var key in obj) {
  				if((len = key.length) > max_len && obj.hasOwnProperty(key)) {
  					max_len = len;
  				}
  			}
  			return max_len;
  		},
  		max_unop_len = getMaxKeyLen(unary_ops),
  		max_binop_len = getMaxKeyLen(binary_ops),
  	// Literals
  	// ----------
  	// Store the values to return for the various literals we may encounter
  		literals = {
  			'true': true,
  			'false': false,
  			'null': null
  		},
  	// Except for `this`, which is special. This could be changed to something like `'self'` as well
  		this_str = 'this',
  	// Returns the precedence of a binary operator or `0` if it isn't a binary operator
  		binaryPrecedence = function(op_val) {
  			return binary_ops[op_val] || 0;
  		},
  	// Utility function (gets called from multiple places)
  	// Also note that `a && b` and `a || b` are *logical* expressions, not binary expressions
  		createBinaryExpression = function (operator, left, right) {
  			var type = (operator === '||' || operator === '&&') ? LOGICAL_EXP : BINARY_EXP;
  			return {
  				type: type,
  				operator: operator,
  				left: left,
  				right: right
  			};
  		},
  		// `ch` is a character code in the next three functions
  		isDecimalDigit = function(ch) {
  			return (ch >= 48 && ch <= 57); // 0...9
  		},
  		isIdentifierStart = function(ch) {
  			return (ch === 36) || (ch === 95) || // `$` and `_`
  					(ch >= 65 && ch <= 90) || // A...Z
  					(ch >= 97 && ch <= 122) || // a...z
                      (ch >= 128 && !binary_ops[String.fromCharCode(ch)]); // any non-ASCII that is not an operator
  		},
  		isIdentifierPart = function(ch) {
  			return (ch === 36) || (ch === 95) || // `$` and `_`
  					(ch >= 65 && ch <= 90) || // A...Z
  					(ch >= 97 && ch <= 122) || // a...z
  					(ch >= 48 && ch <= 57) || // 0...9
                      (ch >= 128 && !binary_ops[String.fromCharCode(ch)]); // any non-ASCII that is not an operator
  		},

  		// Parsing
  		// -------
  		// `expr` is a string with the passed in expression
  		jsep = function(expr) {
  			// `index` stores the character number we are currently at while `length` is a constant
  			// All of the gobbles below will modify `index` as we move along
  			var index = 0,
  				charAtFunc = expr.charAt,
  				charCodeAtFunc = expr.charCodeAt,
  				exprI = function(i) { return charAtFunc.call(expr, i); },
  				exprICode = function(i) { return charCodeAtFunc.call(expr, i); },
  				length = expr.length,

  				// Push `index` up to the next non-space character
  				gobbleSpaces = function() {
  					var ch = exprICode(index);
  					// space or tab
  					while(ch === 32 || ch === 9) {
  						ch = exprICode(++index);
  					}
  				},

  				// The main parsing function. Much of this code is dedicated to ternary expressions
  				gobbleExpression = function() {
  					var test = gobbleBinaryExpression(),
  						consequent, alternate;
  					gobbleSpaces();
  					if(exprICode(index) === QUMARK_CODE) {
  						// Ternary expression: test ? consequent : alternate
  						index++;
  						consequent = gobbleExpression();
  						if(!consequent) {
  							throwError('Expected expression', index);
  						}
  						gobbleSpaces();
  						if(exprICode(index) === COLON_CODE) {
  							index++;
  							alternate = gobbleExpression();
  							if(!alternate) {
  								throwError('Expected expression', index);
  							}
  							return {
  								type: CONDITIONAL_EXP,
  								test: test,
  								consequent: consequent,
  								alternate: alternate
  							};
  						} else {
  							throwError('Expected :', index);
  						}
  					} else {
  						return test;
  					}
  				},

  				// Search for the operation portion of the string (e.g. `+`, `===`)
  				// Start by taking the longest possible binary operations (3 characters: `===`, `!==`, `>>>`)
  				// and move down from 3 to 2 to 1 character until a matching binary operation is found
  				// then, return that binary operation
  				gobbleBinaryOp = function() {
  					gobbleSpaces();
  					var to_check = expr.substr(index, max_binop_len), tc_len = to_check.length;
  					while(tc_len > 0) {
  						if(binary_ops.hasOwnProperty(to_check)) {
  							index += tc_len;
  							return to_check;
  						}
  						to_check = to_check.substr(0, --tc_len);
  					}
  					return false;
  				},

  				// This function is responsible for gobbling an individual expression,
  				// e.g. `1`, `1+2`, `a+(b*2)-Math.sqrt(2)`
  				gobbleBinaryExpression = function() {
  					var node, biop, prec, stack, biop_info, left, right, i;

  					// First, try to get the leftmost thing
  					// Then, check to see if there's a binary operator operating on that leftmost thing
  					left = gobbleToken();
  					biop = gobbleBinaryOp();

  					// If there wasn't a binary operator, just return the leftmost node
  					if(!biop) {
  						return left;
  					}

  					// Otherwise, we need to start a stack to properly place the binary operations in their
  					// precedence structure
  					biop_info = { value: biop, prec: binaryPrecedence(biop)};

  					right = gobbleToken();
  					if(!right) {
  						throwError("Expected expression after " + biop, index);
  					}
  					stack = [left, biop_info, right];

  					// Properly deal with precedence using [recursive descent](http://www.engr.mun.ca/~theo/Misc/exp_parsing.htm)
  					while((biop = gobbleBinaryOp())) {
  						prec = binaryPrecedence(biop);

  						if(prec === 0) {
  							break;
  						}
  						biop_info = { value: biop, prec: prec };

  						// Reduce: make a binary expression from the three topmost entries.
  						while ((stack.length > 2) && (prec <= stack[stack.length - 2].prec)) {
  							right = stack.pop();
  							biop = stack.pop().value;
  							left = stack.pop();
  							node = createBinaryExpression(biop, left, right);
  							stack.push(node);
  						}

  						node = gobbleToken();
  						if(!node) {
  							throwError("Expected expression after " + biop, index);
  						}
  						stack.push(biop_info, node);
  					}

  					i = stack.length - 1;
  					node = stack[i];
  					while(i > 1) {
  						node = createBinaryExpression(stack[i - 1].value, stack[i - 2], node);
  						i -= 2;
  					}
  					return node;
  				},

  				// An individual part of a binary expression:
  				// e.g. `foo.bar(baz)`, `1`, `"abc"`, `(a % 2)` (because it's in parenthesis)
  				gobbleToken = function() {
  					var ch, to_check, tc_len;

  					gobbleSpaces();
  					ch = exprICode(index);

  					if(isDecimalDigit(ch) || ch === PERIOD_CODE) {
  						// Char code 46 is a dot `.` which can start off a numeric literal
  						return gobbleNumericLiteral();
  					} else if(ch === SQUOTE_CODE || ch === DQUOTE_CODE) {
  						// Single or double quotes
  						return gobbleStringLiteral();
  					} else if(isIdentifierStart(ch) || ch === OPAREN_CODE) { // open parenthesis
  						// `foo`, `bar.baz`
  						return gobbleVariable();
  					} else if (ch === OBRACK_CODE) {
  						return gobbleArray();
  					} else {
  						to_check = expr.substr(index, max_unop_len);
  						tc_len = to_check.length;
  						while(tc_len > 0) {
  							if(unary_ops.hasOwnProperty(to_check)) {
  								index += tc_len;
  								return {
  									type: UNARY_EXP,
  									operator: to_check,
  									argument: gobbleToken(),
  									prefix: true
  								};
  							}
  							to_check = to_check.substr(0, --tc_len);
  						}

  						return false;
  					}
  				},
  				// Parse simple numeric literals: `12`, `3.4`, `.5`. Do this by using a string to
  				// keep track of everything in the numeric literal and then calling `parseFloat` on that string
  				gobbleNumericLiteral = function() {
  					var number = '', ch, chCode;
  					while(isDecimalDigit(exprICode(index))) {
  						number += exprI(index++);
  					}

  					if(exprICode(index) === PERIOD_CODE) { // can start with a decimal marker
  						number += exprI(index++);

  						while(isDecimalDigit(exprICode(index))) {
  							number += exprI(index++);
  						}
  					}

  					ch = exprI(index);
  					if(ch === 'e' || ch === 'E') { // exponent marker
  						number += exprI(index++);
  						ch = exprI(index);
  						if(ch === '+' || ch === '-') { // exponent sign
  							number += exprI(index++);
  						}
  						while(isDecimalDigit(exprICode(index))) { //exponent itself
  							number += exprI(index++);
  						}
  						if(!isDecimalDigit(exprICode(index-1)) ) {
  							throwError('Expected exponent (' + number + exprI(index) + ')', index);
  						}
  					}


  					chCode = exprICode(index);
  					// Check to make sure this isn't a variable name that start with a number (123abc)
  					if(isIdentifierStart(chCode)) {
  						throwError('Variable names cannot start with a number (' +
  									number + exprI(index) + ')', index);
  					} else if(chCode === PERIOD_CODE) {
  						throwError('Unexpected period', index);
  					}

  					return {
  						type: LITERAL,
  						value: parseFloat(number),
  						raw: number
  					};
  				},

  				// Parses a string literal, staring with single or double quotes with basic support for escape codes
  				// e.g. `"hello world"`, `'this is\nJSEP'`
  				gobbleStringLiteral = function() {
  					var str = '', quote = exprI(index++), closed = false, ch;

  					while(index < length) {
  						ch = exprI(index++);
  						if(ch === quote) {
  							closed = true;
  							break;
  						} else if(ch === '\\') {
  							// Check for all of the common escape codes
  							ch = exprI(index++);
  							switch(ch) {
  								case 'n': str += '\n'; break;
  								case 'r': str += '\r'; break;
  								case 't': str += '\t'; break;
  								case 'b': str += '\b'; break;
  								case 'f': str += '\f'; break;
  								case 'v': str += '\x0B'; break;
  								default : str += '\\' + ch;
  							}
  						} else {
  							str += ch;
  						}
  					}

  					if(!closed) {
  						throwError('Unclosed quote after "'+str+'"', index);
  					}

  					return {
  						type: LITERAL,
  						value: str,
  						raw: quote + str + quote
  					};
  				},

  				// Gobbles only identifiers
  				// e.g.: `foo`, `_value`, `$x1`
  				// Also, this function checks if that identifier is a literal:
  				// (e.g. `true`, `false`, `null`) or `this`
  				gobbleIdentifier = function() {
  					var ch = exprICode(index), start = index, identifier;

  					if(isIdentifierStart(ch)) {
  						index++;
  					} else {
  						throwError('Unexpected ' + exprI(index), index);
  					}

  					while(index < length) {
  						ch = exprICode(index);
  						if(isIdentifierPart(ch)) {
  							index++;
  						} else {
  							break;
  						}
  					}
  					identifier = expr.slice(start, index);

  					if(literals.hasOwnProperty(identifier)) {
  						return {
  							type: LITERAL,
  							value: literals[identifier],
  							raw: identifier
  						};
  					} else if(identifier === this_str) {
  						return { type: THIS_EXP };
  					} else {
  						return {
  							type: IDENTIFIER,
  							name: identifier
  						};
  					}
  				},

  				// Gobbles a list of arguments within the context of a function call
  				// or array literal. This function also assumes that the opening character
  				// `(` or `[` has already been gobbled, and gobbles expressions and commas
  				// until the terminator character `)` or `]` is encountered.
  				// e.g. `foo(bar, baz)`, `my_func()`, or `[bar, baz]`
  				gobbleArguments = function(termination) {
  					var ch_i, args = [], node, closed = false;
  					while(index < length) {
  						gobbleSpaces();
  						ch_i = exprICode(index);
  						if(ch_i === termination) { // done parsing
  							closed = true;
  							index++;
  							break;
  						} else if (ch_i === COMMA_CODE) { // between expressions
  							index++;
  						} else {
  							node = gobbleExpression();
  							if(!node || node.type === COMPOUND) {
  								throwError('Expected comma', index);
  							}
  							args.push(node);
  						}
  					}
  					if (!closed) {
  						throwError('Expected ' + String.fromCharCode(termination), index);
  					}
  					return args;
  				},

  				// Gobble a non-literal variable name. This variable name may include properties
  				// e.g. `foo`, `bar.baz`, `foo['bar'].baz`
  				// It also gobbles function calls:
  				// e.g. `Math.acos(obj.angle)`
  				gobbleVariable = function() {
  					var ch_i, node;
  					ch_i = exprICode(index);

  					if(ch_i === OPAREN_CODE) {
  						node = gobbleGroup();
  					} else {
  						node = gobbleIdentifier();
  					}
  					gobbleSpaces();
  					ch_i = exprICode(index);
  					while(ch_i === PERIOD_CODE || ch_i === OBRACK_CODE || ch_i === OPAREN_CODE) {
  						index++;
  						if(ch_i === PERIOD_CODE) {
  							gobbleSpaces();
  							node = {
  								type: MEMBER_EXP,
  								computed: false,
  								object: node,
  								property: gobbleIdentifier()
  							};
  						} else if(ch_i === OBRACK_CODE) {
  							node = {
  								type: MEMBER_EXP,
  								computed: true,
  								object: node,
  								property: gobbleExpression()
  							};
  							gobbleSpaces();
  							ch_i = exprICode(index);
  							if(ch_i !== CBRACK_CODE) {
  								throwError('Unclosed [', index);
  							}
  							index++;
  						} else if(ch_i === OPAREN_CODE) {
  							// A function call is being made; gobble all the arguments
  							node = {
  								type: CALL_EXP,
  								'arguments': gobbleArguments(CPAREN_CODE),
  								callee: node
  							};
  						}
  						gobbleSpaces();
  						ch_i = exprICode(index);
  					}
  					return node;
  				},

  				// Responsible for parsing a group of things within parentheses `()`
  				// This function assumes that it needs to gobble the opening parenthesis
  				// and then tries to gobble everything within that parenthesis, assuming
  				// that the next thing it should see is the close parenthesis. If not,
  				// then the expression probably doesn't have a `)`
  				gobbleGroup = function() {
  					index++;
  					var node = gobbleExpression();
  					gobbleSpaces();
  					if(exprICode(index) === CPAREN_CODE) {
  						index++;
  						return node;
  					} else {
  						throwError('Unclosed (', index);
  					}
  				},

  				// Responsible for parsing Array literals `[1, 2, 3]`
  				// This function assumes that it needs to gobble the opening bracket
  				// and then tries to gobble the expressions as arguments.
  				gobbleArray = function() {
  					index++;
  					return {
  						type: ARRAY_EXP,
  						elements: gobbleArguments(CBRACK_CODE)
  					};
  				},

  				nodes = [], ch_i, node;

  			while(index < length) {
  				ch_i = exprICode(index);

  				// Expressions can be separated by semicolons, commas, or just inferred without any
  				// separators
  				if(ch_i === SEMCOL_CODE || ch_i === COMMA_CODE) {
  					index++; // ignore separators
  				} else {
  					// Try to gobble each expression individually
  					if((node = gobbleExpression())) {
  						nodes.push(node);
  					// If we weren't able to find a binary expression and are out of room, then
  					// the expression passed in probably has too much
  					} else if(index < length) {
  						throwError('Unexpected "' + exprI(index) + '"', index);
  					}
  				}
  			}

  			// If there's only one expression just try returning the expression
  			if(nodes.length === 1) {
  				return nodes[0];
  			} else {
  				return {
  					type: COMPOUND,
  					body: nodes
  				};
  			}
  		};

  	// To be filled in by the template
  	jsep.version = '0.3.1';
  	jsep.toString = function() { return 'JavaScript Expression Parser (JSEP) v' + jsep.version; };

  	/**
  	 * @method jsep.addUnaryOp
  	 * @param {string} op_name The name of the unary op to add
  	 * @return jsep
  	 */
  	jsep.addUnaryOp = function(op_name) {
  		max_unop_len = Math.max(op_name.length, max_unop_len);
  		unary_ops[op_name] = t; return this;
  	};

  	/**
  	 * @method jsep.addBinaryOp
  	 * @param {string} op_name The name of the binary op to add
  	 * @param {number} precedence The precedence of the binary op (can be a float)
  	 * @return jsep
  	 */
  	jsep.addBinaryOp = function(op_name, precedence) {
  		max_binop_len = Math.max(op_name.length, max_binop_len);
  		binary_ops[op_name] = precedence;
  		return this;
  	};

  	/**
  	 * @method jsep.addLiteral
  	 * @param {string} literal_name The name of the literal to add
  	 * @param {*} literal_value The value of the literal
  	 * @return jsep
  	 */
  	jsep.addLiteral = function(literal_name, literal_value) {
  		literals[literal_name] = literal_value;
  		return this;
  	};

  	/**
  	 * @method jsep.removeUnaryOp
  	 * @param {string} op_name The name of the unary op to remove
  	 * @return jsep
  	 */
  	jsep.removeUnaryOp = function(op_name) {
  		delete unary_ops[op_name];
  		if(op_name.length === max_unop_len) {
  			max_unop_len = getMaxKeyLen(unary_ops);
  		}
  		return this;
  	};

  	/**
  	 * @method jsep.removeAllUnaryOps
  	 * @return jsep
  	 */
  	jsep.removeAllUnaryOps = function() {
  		unary_ops = {};
  		max_unop_len = 0;

  		return this;
  	};

  	/**
  	 * @method jsep.removeBinaryOp
  	 * @param {string} op_name The name of the binary op to remove
  	 * @return jsep
  	 */
  	jsep.removeBinaryOp = function(op_name) {
  		delete binary_ops[op_name];
  		if(op_name.length === max_binop_len) {
  			max_binop_len = getMaxKeyLen(binary_ops);
  		}
  		return this;
  	};

  	/**
  	 * @method jsep.removeAllBinaryOps
  	 * @return jsep
  	 */
  	jsep.removeAllBinaryOps = function() {
  		binary_ops = {};
  		max_binop_len = 0;

  		return this;
  	};

  	/**
  	 * @method jsep.removeLiteral
  	 * @param {string} literal_name The name of the literal to remove
  	 * @return jsep
  	 */
  	jsep.removeLiteral = function(literal_name) {
  		delete literals[literal_name];
  		return this;
  	};

  	/**
  	 * @method jsep.removeAllLiterals
  	 * @return jsep
  	 */
  	jsep.removeAllLiterals = function() {
  		literals = {};

  		return this;
  	};

      root.jsep = jsep;
  }(tmp$2));

  var jsep = tmp$2.jsep;

  /**
   * @private
   */
  var ExpressionNodeType = {
    VARIABLE: 0,
    UNARY: 1,
    BINARY: 2,
    TERNARY: 3,
    CONDITIONAL: 4,
    MEMBER: 5,
    FUNCTION_CALL: 6,
    ARRAY: 7,
    REGEX: 8,
    VARIABLE_IN_STRING: 9,
    LITERAL_NULL: 10,
    LITERAL_BOOLEAN: 11,
    LITERAL_NUMBER: 12,
    LITERAL_STRING: 13,
    LITERAL_COLOR: 14,
    LITERAL_VECTOR: 15,
    LITERAL_REGEX: 16,
    LITERAL_UNDEFINED: 17,
    BUILTIN_VARIABLE: 18,
  };
  var ExpressionNodeType$1 = Object.freeze(ExpressionNodeType);

  /**
   * An expression for a style applied to a {@link Cesium3DTileset}.
   * <p>
   * Evaluates an expression defined using the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}.
   * </p>
   * <p>
   * Implements the {@link StyleExpression} interface.
   * </p>
   *
   * @alias Expression
   * @constructor
   *
   * @param {String} [expression] The expression defined using the 3D Tiles Styling language.
   * @param {Object} [defines] Defines in the style.
   *
   * @example
   * var expression = new Cesium.Expression('(regExp("^Chest").test(${County})) && (${YearBuilt} >= 1970)');
   * expression.evaluate(feature); // returns true or false depending on the feature's properties
   *
   * @example
   * var expression = new Cesium.Expression('(${Temperature} > 90) ? color("red") : color("white")');
   * expression.evaluateColor(feature, result); // returns a Cesium.Color object
   */
  function Expression(expression, defines) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("expression", expression);
    //>>includeEnd('debug');

    this._expression = expression;
    expression = replaceDefines(expression, defines);
    expression = replaceVariables(removeBackslashes(expression));

    // customize jsep operators
    jsep.addBinaryOp("=~", 0);
    jsep.addBinaryOp("!~", 0);

    var ast;
    try {
      ast = jsep(expression);
    } catch (e) {
      throw new RuntimeError(e);
    }

    this._runtimeAst = createRuntimeAst(this, ast);
  }

  Object.defineProperties(Expression.prototype, {
    /**
     * Gets the expression defined in the 3D Tiles Styling language.
     *
     * @memberof Expression.prototype
     *
     * @type {String}
     * @readonly
     *
     * @default undefined
     */
    expression: {
      get: function () {
        return this._expression;
      },
    },
  });

  // Scratch storage manager while evaluating deep expressions.
  // For example, an expression like dot(vec4(${red}), vec4(${green}) * vec4(${blue}) requires 3 scratch Cartesian4's
  var scratchStorage = {
    arrayIndex: 0,
    arrayArray: [[]],
    cartesian2Index: 0,
    cartesian3Index: 0,
    cartesian4Index: 0,
    cartesian2Array: [new Cartesian2()],
    cartesian3Array: [new Cartesian3()],
    cartesian4Array: [new Cartesian4()],
    reset: function () {
      this.arrayIndex = 0;
      this.cartesian2Index = 0;
      this.cartesian3Index = 0;
      this.cartesian4Index = 0;
    },
    getArray: function () {
      if (this.arrayIndex >= this.arrayArray.length) {
        this.arrayArray.push([]);
      }
      var array = this.arrayArray[this.arrayIndex++];
      array.length = 0;
      return array;
    },
    getCartesian2: function () {
      if (this.cartesian2Index >= this.cartesian2Array.length) {
        this.cartesian2Array.push(new Cartesian2());
      }
      return this.cartesian2Array[this.cartesian2Index++];
    },
    getCartesian3: function () {
      if (this.cartesian3Index >= this.cartesian3Array.length) {
        this.cartesian3Array.push(new Cartesian3());
      }
      return this.cartesian3Array[this.cartesian3Index++];
    },
    getCartesian4: function () {
      if (this.cartesian4Index >= this.cartesian4Array.length) {
        this.cartesian4Array.push(new Cartesian4());
      }
      return this.cartesian4Array[this.cartesian4Index++];
    },
  };

  /**
   * Evaluates the result of an expression, optionally using the provided feature's properties. If the result of
   * the expression in the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
   * is of type <code>Boolean</code>, <code>Number</code>, or <code>String</code>, the corresponding JavaScript
   * primitive type will be returned. If the result is a <code>RegExp</code>, a Javascript <code>RegExp</code>
   * object will be returned. If the result is a <code>Cartesian2</code>, <code>Cartesian3</code>, or <code>Cartesian4</code>,
   * a {@link Cartesian2}, {@link Cartesian3}, or {@link Cartesian4} object will be returned. If the <code>result</code> argument is
   * a {@link Color}, the {@link Cartesian4} value is converted to a {@link Color} and then returned.
   *
   * @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
   * @param {Object} [result] The object onto which to store the result.
   * @returns {Boolean|Number|String|RegExp|Cartesian2|Cartesian3|Cartesian4|Color} The result of evaluating the expression.
   */
  Expression.prototype.evaluate = function (feature, result) {
    scratchStorage.reset();
    var value = this._runtimeAst.evaluate(feature);
    if (result instanceof Color && value instanceof Cartesian4) {
      return Color.fromCartesian4(value, result);
    }
    if (
      value instanceof Cartesian2 ||
      value instanceof Cartesian3 ||
      value instanceof Cartesian4
    ) {
      return value.clone(result);
    }
    return value;
  };

  /**
   * Evaluates the result of a Color expression, optionally using the provided feature's properties.
   * <p>
   * This is equivalent to {@link Expression#evaluate} but always returns a {@link Color} object.
   * </p>
   *
   * @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
   * @param {Color} [result] The object in which to store the result
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   */
  Expression.prototype.evaluateColor = function (feature, result) {
    scratchStorage.reset();
    var color = this._runtimeAst.evaluate(feature);
    return Color.fromCartesian4(color, result);
  };

  /**
   * Gets the shader function for this expression.
   * Returns undefined if the shader function can't be generated from this expression.
   *
   * @param {String} functionName Name to give to the generated function.
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   * @param {String} returnType The return type of the generated function.
   *
   * @returns {String} The shader function.
   *
   * @private
   */
  Expression.prototype.getShaderFunction = function (
    functionName,
    propertyNameMap,
    shaderState,
    returnType
  ) {
    var shaderExpression = this.getShaderExpression(propertyNameMap, shaderState);

    shaderExpression =
      returnType +
      " " +
      functionName +
      "() \n" +
      "{ \n" +
      "    return " +
      shaderExpression +
      "; \n" +
      "} \n";

    return shaderExpression;
  };

  /**
   * Gets the shader expression for this expression.
   * Returns undefined if the shader expression can't be generated from this expression.
   *
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   *
   * @returns {String} The shader expression.
   *
   * @private
   */
  Expression.prototype.getShaderExpression = function (
    propertyNameMap,
    shaderState
  ) {
    return this._runtimeAst.getShaderExpression(propertyNameMap, shaderState);
  };

  var unaryOperators = ["!", "-", "+"];
  var binaryOperators = [
    "+",
    "-",
    "*",
    "/",
    "%",
    "===",
    "!==",
    ">",
    ">=",
    "<",
    "<=",
    "&&",
    "||",
    "!~",
    "=~",
  ];

  var variableRegex = /\${(.*?)}/g; // Matches ${variable_name}
  var backslashRegex = /\\/g;
  var backslashReplacement = "@#%";
  var replacementRegex = /@#%/g;

  var scratchColor$2 = new Color();

  var unaryFunctions = {
    abs: getEvaluateUnaryComponentwise(Math.abs),
    sqrt: getEvaluateUnaryComponentwise(Math.sqrt),
    cos: getEvaluateUnaryComponentwise(Math.cos),
    sin: getEvaluateUnaryComponentwise(Math.sin),
    tan: getEvaluateUnaryComponentwise(Math.tan),
    acos: getEvaluateUnaryComponentwise(Math.acos),
    asin: getEvaluateUnaryComponentwise(Math.asin),
    atan: getEvaluateUnaryComponentwise(Math.atan),
    radians: getEvaluateUnaryComponentwise(CesiumMath.toRadians),
    degrees: getEvaluateUnaryComponentwise(CesiumMath.toDegrees),
    sign: getEvaluateUnaryComponentwise(CesiumMath.sign),
    floor: getEvaluateUnaryComponentwise(Math.floor),
    ceil: getEvaluateUnaryComponentwise(Math.ceil),
    round: getEvaluateUnaryComponentwise(Math.round),
    exp: getEvaluateUnaryComponentwise(Math.exp),
    exp2: getEvaluateUnaryComponentwise(exp2),
    log: getEvaluateUnaryComponentwise(Math.log),
    log2: getEvaluateUnaryComponentwise(log2),
    fract: getEvaluateUnaryComponentwise(fract),
    length: length,
    normalize: normalize,
  };

  var binaryFunctions = {
    atan2: getEvaluateBinaryComponentwise(Math.atan2, false),
    pow: getEvaluateBinaryComponentwise(Math.pow, false),
    min: getEvaluateBinaryComponentwise(Math.min, true),
    max: getEvaluateBinaryComponentwise(Math.max, true),
    distance: distance,
    dot: dot,
    cross: cross,
  };

  var ternaryFunctions = {
    clamp: getEvaluateTernaryComponentwise(CesiumMath.clamp, true),
    mix: getEvaluateTernaryComponentwise(CesiumMath.lerp, true),
  };

  function fract(number) {
    return number - Math.floor(number);
  }

  function exp2(exponent) {
    return Math.pow(2.0, exponent);
  }

  function log2(number) {
    return CesiumMath.log2(number);
  }

  function getEvaluateUnaryComponentwise(operation) {
    return function (call, left) {
      if (typeof left === "number") {
        return operation(left);
      } else if (left instanceof Cartesian2) {
        return Cartesian2.fromElements(
          operation(left.x),
          operation(left.y),
          scratchStorage.getCartesian2()
        );
      } else if (left instanceof Cartesian3) {
        return Cartesian3.fromElements(
          operation(left.x),
          operation(left.y),
          operation(left.z),
          scratchStorage.getCartesian3()
        );
      } else if (left instanceof Cartesian4) {
        return Cartesian4.fromElements(
          operation(left.x),
          operation(left.y),
          operation(left.z),
          operation(left.w),
          scratchStorage.getCartesian4()
        );
      }
      throw new RuntimeError(
        'Function "' +
          call +
          '" requires a vector or number argument. Argument is ' +
          left +
          "."
      );
    };
  }

  function getEvaluateBinaryComponentwise(operation, allowScalar) {
    return function (call, left, right) {
      if (allowScalar && typeof right === "number") {
        if (typeof left === "number") {
          return operation(left, right);
        } else if (left instanceof Cartesian2) {
          return Cartesian2.fromElements(
            operation(left.x, right),
            operation(left.y, right),
            scratchStorage.getCartesian2()
          );
        } else if (left instanceof Cartesian3) {
          return Cartesian3.fromElements(
            operation(left.x, right),
            operation(left.y, right),
            operation(left.z, right),
            scratchStorage.getCartesian3()
          );
        } else if (left instanceof Cartesian4) {
          return Cartesian4.fromElements(
            operation(left.x, right),
            operation(left.y, right),
            operation(left.z, right),
            operation(left.w, right),
            scratchStorage.getCartesian4()
          );
        }
      }

      if (typeof left === "number" && typeof right === "number") {
        return operation(left, right);
      } else if (left instanceof Cartesian2 && right instanceof Cartesian2) {
        return Cartesian2.fromElements(
          operation(left.x, right.x),
          operation(left.y, right.y),
          scratchStorage.getCartesian2()
        );
      } else if (left instanceof Cartesian3 && right instanceof Cartesian3) {
        return Cartesian3.fromElements(
          operation(left.x, right.x),
          operation(left.y, right.y),
          operation(left.z, right.z),
          scratchStorage.getCartesian3()
        );
      } else if (left instanceof Cartesian4 && right instanceof Cartesian4) {
        return Cartesian4.fromElements(
          operation(left.x, right.x),
          operation(left.y, right.y),
          operation(left.z, right.z),
          operation(left.w, right.w),
          scratchStorage.getCartesian4()
        );
      }

      throw new RuntimeError(
        'Function "' +
          call +
          '" requires vector or number arguments of matching types. Arguments are ' +
          left +
          " and " +
          right +
          "."
      );
    };
  }

  function getEvaluateTernaryComponentwise(operation, allowScalar) {
    return function (call, left, right, test) {
      if (allowScalar && typeof test === "number") {
        if (typeof left === "number" && typeof right === "number") {
          return operation(left, right, test);
        } else if (left instanceof Cartesian2 && right instanceof Cartesian2) {
          return Cartesian2.fromElements(
            operation(left.x, right.x, test),
            operation(left.y, right.y, test),
            scratchStorage.getCartesian2()
          );
        } else if (left instanceof Cartesian3 && right instanceof Cartesian3) {
          return Cartesian3.fromElements(
            operation(left.x, right.x, test),
            operation(left.y, right.y, test),
            operation(left.z, right.z, test),
            scratchStorage.getCartesian3()
          );
        } else if (left instanceof Cartesian4 && right instanceof Cartesian4) {
          return Cartesian4.fromElements(
            operation(left.x, right.x, test),
            operation(left.y, right.y, test),
            operation(left.z, right.z, test),
            operation(left.w, right.w, test),
            scratchStorage.getCartesian4()
          );
        }
      }

      if (
        typeof left === "number" &&
        typeof right === "number" &&
        typeof test === "number"
      ) {
        return operation(left, right, test);
      } else if (
        left instanceof Cartesian2 &&
        right instanceof Cartesian2 &&
        test instanceof Cartesian2
      ) {
        return Cartesian2.fromElements(
          operation(left.x, right.x, test.x),
          operation(left.y, right.y, test.y),
          scratchStorage.getCartesian2()
        );
      } else if (
        left instanceof Cartesian3 &&
        right instanceof Cartesian3 &&
        test instanceof Cartesian3
      ) {
        return Cartesian3.fromElements(
          operation(left.x, right.x, test.x),
          operation(left.y, right.y, test.y),
          operation(left.z, right.z, test.z),
          scratchStorage.getCartesian3()
        );
      } else if (
        left instanceof Cartesian4 &&
        right instanceof Cartesian4 &&
        test instanceof Cartesian4
      ) {
        return Cartesian4.fromElements(
          operation(left.x, right.x, test.x),
          operation(left.y, right.y, test.y),
          operation(left.z, right.z, test.z),
          operation(left.w, right.w, test.w),
          scratchStorage.getCartesian4()
        );
      }

      throw new RuntimeError(
        'Function "' +
          call +
          '" requires vector or number arguments of matching types. Arguments are ' +
          left +
          ", " +
          right +
          ", and " +
          test +
          "."
      );
    };
  }

  function length(call, left) {
    if (typeof left === "number") {
      return Math.abs(left);
    } else if (left instanceof Cartesian2) {
      return Cartesian2.magnitude(left);
    } else if (left instanceof Cartesian3) {
      return Cartesian3.magnitude(left);
    } else if (left instanceof Cartesian4) {
      return Cartesian4.magnitude(left);
    }

    throw new RuntimeError(
      'Function "' +
        call +
        '" requires a vector or number argument. Argument is ' +
        left +
        "."
    );
  }

  function normalize(call, left) {
    if (typeof left === "number") {
      return 1.0;
    } else if (left instanceof Cartesian2) {
      return Cartesian2.normalize(left, scratchStorage.getCartesian2());
    } else if (left instanceof Cartesian3) {
      return Cartesian3.normalize(left, scratchStorage.getCartesian3());
    } else if (left instanceof Cartesian4) {
      return Cartesian4.normalize(left, scratchStorage.getCartesian4());
    }

    throw new RuntimeError(
      'Function "' +
        call +
        '" requires a vector or number argument. Argument is ' +
        left +
        "."
    );
  }

  function distance(call, left, right) {
    if (typeof left === "number" && typeof right === "number") {
      return Math.abs(left - right);
    } else if (left instanceof Cartesian2 && right instanceof Cartesian2) {
      return Cartesian2.distance(left, right);
    } else if (left instanceof Cartesian3 && right instanceof Cartesian3) {
      return Cartesian3.distance(left, right);
    } else if (left instanceof Cartesian4 && right instanceof Cartesian4) {
      return Cartesian4.distance(left, right);
    }

    throw new RuntimeError(
      'Function "' +
        call +
        '" requires vector or number arguments of matching types. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  }

  function dot(call, left, right) {
    if (typeof left === "number" && typeof right === "number") {
      return left * right;
    } else if (left instanceof Cartesian2 && right instanceof Cartesian2) {
      return Cartesian2.dot(left, right);
    } else if (left instanceof Cartesian3 && right instanceof Cartesian3) {
      return Cartesian3.dot(left, right);
    } else if (left instanceof Cartesian4 && right instanceof Cartesian4) {
      return Cartesian4.dot(left, right);
    }

    throw new RuntimeError(
      'Function "' +
        call +
        '" requires vector or number arguments of matching types. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  }

  function cross(call, left, right) {
    if (left instanceof Cartesian3 && right instanceof Cartesian3) {
      return Cartesian3.cross(left, right, scratchStorage.getCartesian3());
    }

    throw new RuntimeError(
      'Function "' +
        call +
        '" requires vec3 arguments. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  }

  function Node$2(type, value, left, right, test) {
    this._type = type;
    this._value = value;
    this._left = left;
    this._right = right;
    this._test = test;
    this.evaluate = undefined;

    setEvaluateFunction(this);
  }

  function replaceDefines(expression, defines) {
    if (!defined(defines)) {
      return expression;
    }
    for (var key in defines) {
      if (defines.hasOwnProperty(key)) {
        var definePlaceholder = new RegExp("\\$\\{" + key + "\\}", "g");
        var defineReplace = "(" + defines[key] + ")";
        if (defined(defineReplace)) {
          expression = expression.replace(definePlaceholder, defineReplace);
        }
      }
    }
    return expression;
  }

  function removeBackslashes(expression) {
    return expression.replace(backslashRegex, backslashReplacement);
  }

  function replaceBackslashes(expression) {
    return expression.replace(replacementRegex, "\\");
  }

  function replaceVariables(expression) {
    var exp = expression;
    var result = "";
    var i = exp.indexOf("${");
    while (i >= 0) {
      // Check if string is inside quotes
      var openSingleQuote = exp.indexOf("'");
      var openDoubleQuote = exp.indexOf('"');
      var closeQuote;
      if (openSingleQuote >= 0 && openSingleQuote < i) {
        closeQuote = exp.indexOf("'", openSingleQuote + 1);
        result += exp.substr(0, closeQuote + 1);
        exp = exp.substr(closeQuote + 1);
        i = exp.indexOf("${");
      } else if (openDoubleQuote >= 0 && openDoubleQuote < i) {
        closeQuote = exp.indexOf('"', openDoubleQuote + 1);
        result += exp.substr(0, closeQuote + 1);
        exp = exp.substr(closeQuote + 1);
        i = exp.indexOf("${");
      } else {
        result += exp.substr(0, i);
        var j = exp.indexOf("}");
        if (j < 0) {
          throw new RuntimeError("Unmatched {.");
        }
        result += "czm_" + exp.substr(i + 2, j - (i + 2));
        exp = exp.substr(j + 1);
        i = exp.indexOf("${");
      }
    }
    result += exp;
    return result;
  }

  function parseLiteral(ast) {
    var type = typeof ast.value;
    if (ast.value === null) {
      return new Node$2(ExpressionNodeType$1.LITERAL_NULL, null);
    } else if (type === "boolean") {
      return new Node$2(ExpressionNodeType$1.LITERAL_BOOLEAN, ast.value);
    } else if (type === "number") {
      return new Node$2(ExpressionNodeType$1.LITERAL_NUMBER, ast.value);
    } else if (type === "string") {
      if (ast.value.indexOf("${") >= 0) {
        return new Node$2(ExpressionNodeType$1.VARIABLE_IN_STRING, ast.value);
      }
      return new Node$2(
        ExpressionNodeType$1.LITERAL_STRING,
        replaceBackslashes(ast.value)
      );
    }
  }

  function parseCall(expression, ast) {
    var args = ast.arguments;
    var argsLength = args.length;
    var call;
    var val, left, right;

    // Member function calls
    if (ast.callee.type === "MemberExpression") {
      call = ast.callee.property.name;
      var object = ast.callee.object;
      if (call === "test" || call === "exec") {
        // Make sure this is called on a valid type
        if (object.callee.name !== "regExp") {
          throw new RuntimeError(call + " is not a function.");
        }
        if (argsLength === 0) {
          if (call === "test") {
            return new Node$2(ExpressionNodeType$1.LITERAL_BOOLEAN, false);
          }
          return new Node$2(ExpressionNodeType$1.LITERAL_NULL, null);
        }
        left = createRuntimeAst(expression, object);
        right = createRuntimeAst(expression, args[0]);
        return new Node$2(ExpressionNodeType$1.FUNCTION_CALL, call, left, right);
      } else if (call === "toString") {
        val = createRuntimeAst(expression, object);
        return new Node$2(ExpressionNodeType$1.FUNCTION_CALL, call, val);
      }

      throw new RuntimeError('Unexpected function call "' + call + '".');
    }

    // Non-member function calls
    call = ast.callee.name;
    if (call === "color") {
      if (argsLength === 0) {
        return new Node$2(ExpressionNodeType$1.LITERAL_COLOR, call);
      }
      val = createRuntimeAst(expression, args[0]);
      if (defined(args[1])) {
        var alpha = createRuntimeAst(expression, args[1]);
        return new Node$2(ExpressionNodeType$1.LITERAL_COLOR, call, [val, alpha]);
      }
      return new Node$2(ExpressionNodeType$1.LITERAL_COLOR, call, [val]);
    } else if (call === "rgb" || call === "hsl") {
      if (argsLength < 3) {
        throw new RuntimeError(call + " requires three arguments.");
      }
      val = [
        createRuntimeAst(expression, args[0]),
        createRuntimeAst(expression, args[1]),
        createRuntimeAst(expression, args[2]),
      ];
      return new Node$2(ExpressionNodeType$1.LITERAL_COLOR, call, val);
    } else if (call === "rgba" || call === "hsla") {
      if (argsLength < 4) {
        throw new RuntimeError(call + " requires four arguments.");
      }
      val = [
        createRuntimeAst(expression, args[0]),
        createRuntimeAst(expression, args[1]),
        createRuntimeAst(expression, args[2]),
        createRuntimeAst(expression, args[3]),
      ];
      return new Node$2(ExpressionNodeType$1.LITERAL_COLOR, call, val);
    } else if (call === "vec2" || call === "vec3" || call === "vec4") {
      // Check for invalid constructors at evaluation time
      val = new Array(argsLength);
      for (var i = 0; i < argsLength; ++i) {
        val[i] = createRuntimeAst(expression, args[i]);
      }
      return new Node$2(ExpressionNodeType$1.LITERAL_VECTOR, call, val);
    } else if (call === "isNaN" || call === "isFinite") {
      if (argsLength === 0) {
        if (call === "isNaN") {
          return new Node$2(ExpressionNodeType$1.LITERAL_BOOLEAN, true);
        }
        return new Node$2(ExpressionNodeType$1.LITERAL_BOOLEAN, false);
      }
      val = createRuntimeAst(expression, args[0]);
      return new Node$2(ExpressionNodeType$1.UNARY, call, val);
    } else if (call === "isExactClass" || call === "isClass") {
      if (argsLength < 1 || argsLength > 1) {
        throw new RuntimeError(call + " requires exactly one argument.");
      }
      val = createRuntimeAst(expression, args[0]);
      return new Node$2(ExpressionNodeType$1.UNARY, call, val);
    } else if (call === "getExactClassName") {
      if (argsLength > 0) {
        throw new RuntimeError(call + " does not take any argument.");
      }
      return new Node$2(ExpressionNodeType$1.UNARY, call);
    } else if (defined(unaryFunctions[call])) {
      if (argsLength !== 1) {
        throw new RuntimeError(call + " requires exactly one argument.");
      }
      val = createRuntimeAst(expression, args[0]);
      return new Node$2(ExpressionNodeType$1.UNARY, call, val);
    } else if (defined(binaryFunctions[call])) {
      if (argsLength !== 2) {
        throw new RuntimeError(call + " requires exactly two arguments.");
      }
      left = createRuntimeAst(expression, args[0]);
      right = createRuntimeAst(expression, args[1]);
      return new Node$2(ExpressionNodeType$1.BINARY, call, left, right);
    } else if (defined(ternaryFunctions[call])) {
      if (argsLength !== 3) {
        throw new RuntimeError(call + " requires exactly three arguments.");
      }
      left = createRuntimeAst(expression, args[0]);
      right = createRuntimeAst(expression, args[1]);
      var test = createRuntimeAst(expression, args[2]);
      return new Node$2(ExpressionNodeType$1.TERNARY, call, left, right, test);
    } else if (call === "Boolean") {
      if (argsLength === 0) {
        return new Node$2(ExpressionNodeType$1.LITERAL_BOOLEAN, false);
      }
      val = createRuntimeAst(expression, args[0]);
      return new Node$2(ExpressionNodeType$1.UNARY, call, val);
    } else if (call === "Number") {
      if (argsLength === 0) {
        return new Node$2(ExpressionNodeType$1.LITERAL_NUMBER, 0);
      }
      val = createRuntimeAst(expression, args[0]);
      return new Node$2(ExpressionNodeType$1.UNARY, call, val);
    } else if (call === "String") {
      if (argsLength === 0) {
        return new Node$2(ExpressionNodeType$1.LITERAL_STRING, "");
      }
      val = createRuntimeAst(expression, args[0]);
      return new Node$2(ExpressionNodeType$1.UNARY, call, val);
    } else if (call === "regExp") {
      return parseRegex$1(expression, ast);
    }

    throw new RuntimeError('Unexpected function call "' + call + '".');
  }

  function parseRegex$1(expression, ast) {
    var args = ast.arguments;
    // no arguments, return default regex
    if (args.length === 0) {
      return new Node$2(ExpressionNodeType$1.LITERAL_REGEX, new RegExp());
    }

    var pattern = createRuntimeAst(expression, args[0]);
    var exp;

    // optional flag argument supplied
    if (args.length > 1) {
      var flags = createRuntimeAst(expression, args[1]);
      if (isLiteralType(pattern) && isLiteralType(flags)) {
        try {
          exp = new RegExp(
            replaceBackslashes(String(pattern._value)),
            flags._value
          );
        } catch (e) {
          throw new RuntimeError(e);
        }
        return new Node$2(ExpressionNodeType$1.LITERAL_REGEX, exp);
      }
      return new Node$2(ExpressionNodeType$1.REGEX, pattern, flags);
    }

    // only pattern argument supplied
    if (isLiteralType(pattern)) {
      try {
        exp = new RegExp(replaceBackslashes(String(pattern._value)));
      } catch (e) {
        throw new RuntimeError(e);
      }
      return new Node$2(ExpressionNodeType$1.LITERAL_REGEX, exp);
    }
    return new Node$2(ExpressionNodeType$1.REGEX, pattern);
  }

  function parseKeywordsAndVariables(ast) {
    if (isVariable(ast.name)) {
      var name = getPropertyName(ast.name);
      if (name.substr(0, 8) === "tiles3d_") {
        return new Node$2(ExpressionNodeType$1.BUILTIN_VARIABLE, name);
      }
      return new Node$2(ExpressionNodeType$1.VARIABLE, name);
    } else if (ast.name === "NaN") {
      return new Node$2(ExpressionNodeType$1.LITERAL_NUMBER, NaN);
    } else if (ast.name === "Infinity") {
      return new Node$2(ExpressionNodeType$1.LITERAL_NUMBER, Infinity);
    } else if (ast.name === "undefined") {
      return new Node$2(ExpressionNodeType$1.LITERAL_UNDEFINED, undefined);
    }

    throw new RuntimeError(ast.name + " is not defined.");
  }

  function parseMathConstant(ast) {
    var name = ast.property.name;
    if (name === "PI") {
      return new Node$2(ExpressionNodeType$1.LITERAL_NUMBER, Math.PI);
    } else if (name === "E") {
      return new Node$2(ExpressionNodeType$1.LITERAL_NUMBER, Math.E);
    }
  }

  function parseNumberConstant(ast) {
    var name = ast.property.name;
    if (name === "POSITIVE_INFINITY") {
      return new Node$2(
        ExpressionNodeType$1.LITERAL_NUMBER,
        Number.POSITIVE_INFINITY
      );
    }
  }

  function parseMemberExpression(expression, ast) {
    if (ast.object.name === "Math") {
      return parseMathConstant(ast);
    } else if (ast.object.name === "Number") {
      return parseNumberConstant(ast);
    }

    var val;
    var obj = createRuntimeAst(expression, ast.object);
    if (ast.computed) {
      val = createRuntimeAst(expression, ast.property);
      return new Node$2(ExpressionNodeType$1.MEMBER, "brackets", obj, val);
    }

    val = new Node$2(ExpressionNodeType$1.LITERAL_STRING, ast.property.name);
    return new Node$2(ExpressionNodeType$1.MEMBER, "dot", obj, val);
  }

  function isLiteralType(node) {
    return node._type >= ExpressionNodeType$1.LITERAL_NULL;
  }

  function isVariable(name) {
    return name.substr(0, 4) === "czm_";
  }

  function getPropertyName(variable) {
    return variable.substr(4);
  }

  function createRuntimeAst(expression, ast) {
    var node;
    var op;
    var left;
    var right;

    if (ast.type === "Literal") {
      node = parseLiteral(ast);
    } else if (ast.type === "CallExpression") {
      node = parseCall(expression, ast);
    } else if (ast.type === "Identifier") {
      node = parseKeywordsAndVariables(ast);
    } else if (ast.type === "UnaryExpression") {
      op = ast.operator;
      var child = createRuntimeAst(expression, ast.argument);
      if (unaryOperators.indexOf(op) > -1) {
        node = new Node$2(ExpressionNodeType$1.UNARY, op, child);
      } else {
        throw new RuntimeError('Unexpected operator "' + op + '".');
      }
    } else if (ast.type === "BinaryExpression") {
      op = ast.operator;
      left = createRuntimeAst(expression, ast.left);
      right = createRuntimeAst(expression, ast.right);
      if (binaryOperators.indexOf(op) > -1) {
        node = new Node$2(ExpressionNodeType$1.BINARY, op, left, right);
      } else {
        throw new RuntimeError('Unexpected operator "' + op + '".');
      }
    } else if (ast.type === "LogicalExpression") {
      op = ast.operator;
      left = createRuntimeAst(expression, ast.left);
      right = createRuntimeAst(expression, ast.right);
      if (binaryOperators.indexOf(op) > -1) {
        node = new Node$2(ExpressionNodeType$1.BINARY, op, left, right);
      }
    } else if (ast.type === "ConditionalExpression") {
      var test = createRuntimeAst(expression, ast.test);
      left = createRuntimeAst(expression, ast.consequent);
      right = createRuntimeAst(expression, ast.alternate);
      node = new Node$2(ExpressionNodeType$1.CONDITIONAL, "?", left, right, test);
    } else if (ast.type === "MemberExpression") {
      node = parseMemberExpression(expression, ast);
    } else if (ast.type === "ArrayExpression") {
      var val = [];
      for (var i = 0; i < ast.elements.length; i++) {
        val[i] = createRuntimeAst(expression, ast.elements[i]);
      }
      node = new Node$2(ExpressionNodeType$1.ARRAY, val);
    } else if (ast.type === "Compound") {
      // empty expression or multiple expressions
      throw new RuntimeError("Provide exactly one expression.");
    } else {
      throw new RuntimeError("Cannot parse expression.");
    }

    return node;
  }

  function setEvaluateFunction(node) {
    if (node._type === ExpressionNodeType$1.CONDITIONAL) {
      node.evaluate = node._evaluateConditional;
    } else if (node._type === ExpressionNodeType$1.FUNCTION_CALL) {
      if (node._value === "test") {
        node.evaluate = node._evaluateRegExpTest;
      } else if (node._value === "exec") {
        node.evaluate = node._evaluateRegExpExec;
      } else if (node._value === "toString") {
        node.evaluate = node._evaluateToString;
      }
    } else if (node._type === ExpressionNodeType$1.UNARY) {
      if (node._value === "!") {
        node.evaluate = node._evaluateNot;
      } else if (node._value === "-") {
        node.evaluate = node._evaluateNegative;
      } else if (node._value === "+") {
        node.evaluate = node._evaluatePositive;
      } else if (node._value === "isNaN") {
        node.evaluate = node._evaluateNaN;
      } else if (node._value === "isFinite") {
        node.evaluate = node._evaluateIsFinite;
      } else if (node._value === "isExactClass") {
        node.evaluate = node._evaluateIsExactClass;
      } else if (node._value === "isClass") {
        node.evaluate = node._evaluateIsClass;
      } else if (node._value === "getExactClassName") {
        node.evaluate = node._evaluateGetExactClassName;
      } else if (node._value === "Boolean") {
        node.evaluate = node._evaluateBooleanConversion;
      } else if (node._value === "Number") {
        node.evaluate = node._evaluateNumberConversion;
      } else if (node._value === "String") {
        node.evaluate = node._evaluateStringConversion;
      } else if (defined(unaryFunctions[node._value])) {
        node.evaluate = getEvaluateUnaryFunction(node._value);
      }
    } else if (node._type === ExpressionNodeType$1.BINARY) {
      if (node._value === "+") {
        node.evaluate = node._evaluatePlus;
      } else if (node._value === "-") {
        node.evaluate = node._evaluateMinus;
      } else if (node._value === "*") {
        node.evaluate = node._evaluateTimes;
      } else if (node._value === "/") {
        node.evaluate = node._evaluateDivide;
      } else if (node._value === "%") {
        node.evaluate = node._evaluateMod;
      } else if (node._value === "===") {
        node.evaluate = node._evaluateEqualsStrict;
      } else if (node._value === "!==") {
        node.evaluate = node._evaluateNotEqualsStrict;
      } else if (node._value === "<") {
        node.evaluate = node._evaluateLessThan;
      } else if (node._value === "<=") {
        node.evaluate = node._evaluateLessThanOrEquals;
      } else if (node._value === ">") {
        node.evaluate = node._evaluateGreaterThan;
      } else if (node._value === ">=") {
        node.evaluate = node._evaluateGreaterThanOrEquals;
      } else if (node._value === "&&") {
        node.evaluate = node._evaluateAnd;
      } else if (node._value === "||") {
        node.evaluate = node._evaluateOr;
      } else if (node._value === "=~") {
        node.evaluate = node._evaluateRegExpMatch;
      } else if (node._value === "!~") {
        node.evaluate = node._evaluateRegExpNotMatch;
      } else if (defined(binaryFunctions[node._value])) {
        node.evaluate = getEvaluateBinaryFunction(node._value);
      }
    } else if (node._type === ExpressionNodeType$1.TERNARY) {
      node.evaluate = getEvaluateTernaryFunction(node._value);
    } else if (node._type === ExpressionNodeType$1.MEMBER) {
      if (node._value === "brackets") {
        node.evaluate = node._evaluateMemberBrackets;
      } else {
        node.evaluate = node._evaluateMemberDot;
      }
    } else if (node._type === ExpressionNodeType$1.ARRAY) {
      node.evaluate = node._evaluateArray;
    } else if (node._type === ExpressionNodeType$1.VARIABLE) {
      node.evaluate = node._evaluateVariable;
    } else if (node._type === ExpressionNodeType$1.VARIABLE_IN_STRING) {
      node.evaluate = node._evaluateVariableString;
    } else if (node._type === ExpressionNodeType$1.LITERAL_COLOR) {
      node.evaluate = node._evaluateLiteralColor;
    } else if (node._type === ExpressionNodeType$1.LITERAL_VECTOR) {
      node.evaluate = node._evaluateLiteralVector;
    } else if (node._type === ExpressionNodeType$1.LITERAL_STRING) {
      node.evaluate = node._evaluateLiteralString;
    } else if (node._type === ExpressionNodeType$1.REGEX) {
      node.evaluate = node._evaluateRegExp;
    } else if (node._type === ExpressionNodeType$1.BUILTIN_VARIABLE) {
      if (node._value === "tiles3d_tileset_time") {
        node.evaluate = evaluateTilesetTime;
      }
    } else {
      node.evaluate = node._evaluateLiteral;
    }
  }

  function evaluateTilesetTime(feature) {
    if (!defined(feature)) {
      return 0.0;
    }
    return feature.content.tileset.timeSinceLoad;
  }

  function getEvaluateUnaryFunction(call) {
    var evaluate = unaryFunctions[call];
    return function (feature) {
      var left = this._left.evaluate(feature);
      return evaluate(call, left);
    };
  }

  function getEvaluateBinaryFunction(call) {
    var evaluate = binaryFunctions[call];
    return function (feature) {
      var left = this._left.evaluate(feature);
      var right = this._right.evaluate(feature);
      return evaluate(call, left, right);
    };
  }

  function getEvaluateTernaryFunction(call) {
    var evaluate = ternaryFunctions[call];
    return function (feature) {
      var left = this._left.evaluate(feature);
      var right = this._right.evaluate(feature);
      var test = this._test.evaluate(feature);
      return evaluate(call, left, right, test);
    };
  }

  function getFeatureProperty(feature, name) {
    // Returns undefined if the feature is not defined or the property name is not defined for that feature
    if (defined(feature)) {
      return feature.getProperty(name);
    }
  }

  Node$2.prototype._evaluateLiteral = function () {
    return this._value;
  };

  Node$2.prototype._evaluateLiteralColor = function (feature) {
    var color = scratchColor$2;
    var args = this._left;
    if (this._value === "color") {
      if (!defined(args)) {
        Color.fromBytes(255, 255, 255, 255, color);
      } else if (args.length > 1) {
        Color.fromCssColorString(args[0].evaluate(feature), color);
        color.alpha = args[1].evaluate(feature);
      } else {
        Color.fromCssColorString(args[0].evaluate(feature), color);
      }
    } else if (this._value === "rgb") {
      Color.fromBytes(
        args[0].evaluate(feature),
        args[1].evaluate(feature),
        args[2].evaluate(feature),
        255,
        color
      );
    } else if (this._value === "rgba") {
      // convert between css alpha (0 to 1) and cesium alpha (0 to 255)
      var a = args[3].evaluate(feature) * 255;
      Color.fromBytes(
        args[0].evaluate(feature),
        args[1].evaluate(feature),
        args[2].evaluate(feature),
        a,
        color
      );
    } else if (this._value === "hsl") {
      Color.fromHsl(
        args[0].evaluate(feature),
        args[1].evaluate(feature),
        args[2].evaluate(feature),
        1.0,
        color
      );
    } else if (this._value === "hsla") {
      Color.fromHsl(
        args[0].evaluate(feature),
        args[1].evaluate(feature),
        args[2].evaluate(feature),
        args[3].evaluate(feature),
        color
      );
    }
    return Cartesian4.fromColor(color, scratchStorage.getCartesian4());
  };

  Node$2.prototype._evaluateLiteralVector = function (feature) {
    // Gather the components that make up the vector, which includes components from interior vectors.
    // For example vec3(1, 2, 3) or vec3(vec2(1, 2), 3) are both valid.
    //
    // If the number of components does not equal the vector's size, then a RuntimeError is thrown - with two exceptions:
    // 1. A vector may be constructed from a larger vector and drop the extra components.
    // 2. A vector may be constructed from a single component - vec3(1) will become vec3(1, 1, 1).
    //
    // Examples of invalid constructors include:
    // vec4(1, 2)        // not enough components
    // vec3(vec2(1, 2))  // not enough components
    // vec3(1, 2, 3, 4)  // too many components
    // vec2(vec4(1), 1)  // too many components

    var components = scratchStorage.getArray();
    var call = this._value;
    var args = this._left;
    var argsLength = args.length;
    for (var i = 0; i < argsLength; ++i) {
      var value = args[i].evaluate(feature);
      if (typeof value === "number") {
        components.push(value);
      } else if (value instanceof Cartesian2) {
        components.push(value.x, value.y);
      } else if (value instanceof Cartesian3) {
        components.push(value.x, value.y, value.z);
      } else if (value instanceof Cartesian4) {
        components.push(value.x, value.y, value.z, value.w);
      } else {
        throw new RuntimeError(
          call +
            " argument must be a vector or number. Argument is " +
            value +
            "."
        );
      }
    }

    var componentsLength = components.length;
    var vectorLength = parseInt(call.charAt(3));

    if (componentsLength === 0) {
      throw new RuntimeError(
        "Invalid " + call + " constructor. No valid arguments."
      );
    } else if (componentsLength < vectorLength && componentsLength > 1) {
      throw new RuntimeError(
        "Invalid " + call + " constructor. Not enough arguments."
      );
    } else if (componentsLength > vectorLength && argsLength > 1) {
      throw new RuntimeError(
        "Invalid " + call + " constructor. Too many arguments."
      );
    }

    if (componentsLength === 1) {
      // Add the same component 3 more times
      var component = components[0];
      components.push(component, component, component);
    }

    if (call === "vec2") {
      return Cartesian2.fromArray(components, 0, scratchStorage.getCartesian2());
    } else if (call === "vec3") {
      return Cartesian3.fromArray(components, 0, scratchStorage.getCartesian3());
    } else if (call === "vec4") {
      return Cartesian4.fromArray(components, 0, scratchStorage.getCartesian4());
    }
  };

  Node$2.prototype._evaluateLiteralString = function () {
    return this._value;
  };

  Node$2.prototype._evaluateVariableString = function (feature) {
    var result = this._value;
    var match = variableRegex.exec(result);
    while (match !== null) {
      var placeholder = match[0];
      var variableName = match[1];
      var property = getFeatureProperty(feature, variableName);
      if (!defined(property)) {
        property = "";
      }
      result = result.replace(placeholder, property);
      match = variableRegex.exec(result);
    }
    return result;
  };

  Node$2.prototype._evaluateVariable = function (feature) {
    // evaluates to undefined if the property name is not defined for that feature
    return getFeatureProperty(feature, this._value);
  };

  function checkFeature(ast) {
    return ast._value === "feature";
  }

  // PERFORMANCE_IDEA: Determine if parent property needs to be computed before runtime
  Node$2.prototype._evaluateMemberDot = function (feature) {
    if (checkFeature(this._left)) {
      return getFeatureProperty(feature, this._right.evaluate(feature));
    }
    var property = this._left.evaluate(feature);
    if (!defined(property)) {
      return undefined;
    }

    var member = this._right.evaluate(feature);
    if (
      property instanceof Cartesian2 ||
      property instanceof Cartesian3 ||
      property instanceof Cartesian4
    ) {
      // Vector components may be accessed with .r, .g, .b, .a and implicitly with .x, .y, .z, .w
      if (member === "r") {
        return property.x;
      } else if (member === "g") {
        return property.y;
      } else if (member === "b") {
        return property.z;
      } else if (member === "a") {
        return property.w;
      }
    }
    return property[member];
  };

  Node$2.prototype._evaluateMemberBrackets = function (feature) {
    if (checkFeature(this._left)) {
      return getFeatureProperty(feature, this._right.evaluate(feature));
    }
    var property = this._left.evaluate(feature);
    if (!defined(property)) {
      return undefined;
    }

    var member = this._right.evaluate(feature);
    if (
      property instanceof Cartesian2 ||
      property instanceof Cartesian3 ||
      property instanceof Cartesian4
    ) {
      // Vector components may be accessed with [0][1][2][3], ['r']['g']['b']['a'] and implicitly with ['x']['y']['z']['w']
      // For Cartesian2 and Cartesian3 out-of-range components will just return undefined
      if (member === 0 || member === "r") {
        return property.x;
      } else if (member === 1 || member === "g") {
        return property.y;
      } else if (member === 2 || member === "b") {
        return property.z;
      } else if (member === 3 || member === "a") {
        return property.w;
      }
    }
    return property[member];
  };

  Node$2.prototype._evaluateArray = function (feature) {
    var array = [];
    for (var i = 0; i < this._value.length; i++) {
      array[i] = this._value[i].evaluate(feature);
    }
    return array;
  };

  // PERFORMANCE_IDEA: Have "fast path" functions that deal only with specific types
  // that we can assign if we know the types before runtime

  Node$2.prototype._evaluateNot = function (feature) {
    var left = this._left.evaluate(feature);
    if (typeof left !== "boolean") {
      throw new RuntimeError(
        'Operator "!" requires a boolean argument. Argument is ' + left + "."
      );
    }
    return !left;
  };

  Node$2.prototype._evaluateNegative = function (feature) {
    var left = this._left.evaluate(feature);
    if (left instanceof Cartesian2) {
      return Cartesian2.negate(left, scratchStorage.getCartesian2());
    } else if (left instanceof Cartesian3) {
      return Cartesian3.negate(left, scratchStorage.getCartesian3());
    } else if (left instanceof Cartesian4) {
      return Cartesian4.negate(left, scratchStorage.getCartesian4());
    } else if (typeof left === "number") {
      return -left;
    }

    throw new RuntimeError(
      'Operator "-" requires a vector or number argument. Argument is ' +
        left +
        "."
    );
  };

  Node$2.prototype._evaluatePositive = function (feature) {
    var left = this._left.evaluate(feature);

    if (
      !(
        left instanceof Cartesian2 ||
        left instanceof Cartesian3 ||
        left instanceof Cartesian4 ||
        typeof left === "number"
      )
    ) {
      throw new RuntimeError(
        'Operator "+" requires a vector or number argument. Argument is ' +
          left +
          "."
      );
    }

    return left;
  };

  Node$2.prototype._evaluateLessThan = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (typeof left !== "number" || typeof right !== "number") {
      throw new RuntimeError(
        'Operator "<" requires number arguments. Arguments are ' +
          left +
          " and " +
          right +
          "."
      );
    }

    return left < right;
  };

  Node$2.prototype._evaluateLessThanOrEquals = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (typeof left !== "number" || typeof right !== "number") {
      throw new RuntimeError(
        'Operator "<=" requires number arguments. Arguments are ' +
          left +
          " and " +
          right +
          "."
      );
    }

    return left <= right;
  };

  Node$2.prototype._evaluateGreaterThan = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (typeof left !== "number" || typeof right !== "number") {
      throw new RuntimeError(
        'Operator ">" requires number arguments. Arguments are ' +
          left +
          " and " +
          right +
          "."
      );
    }

    return left > right;
  };

  Node$2.prototype._evaluateGreaterThanOrEquals = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (typeof left !== "number" || typeof right !== "number") {
      throw new RuntimeError(
        'Operator ">=" requires number arguments. Arguments are ' +
          left +
          " and " +
          right +
          "."
      );
    }

    return left >= right;
  };

  Node$2.prototype._evaluateOr = function (feature) {
    var left = this._left.evaluate(feature);
    if (typeof left !== "boolean") {
      throw new RuntimeError(
        'Operator "||" requires boolean arguments. First argument is ' +
          left +
          "."
      );
    }

    // short circuit the expression
    if (left) {
      return true;
    }

    var right = this._right.evaluate(feature);
    if (typeof right !== "boolean") {
      throw new RuntimeError(
        'Operator "||" requires boolean arguments. Second argument is ' +
          right +
          "."
      );
    }

    return left || right;
  };

  Node$2.prototype._evaluateAnd = function (feature) {
    var left = this._left.evaluate(feature);
    if (typeof left !== "boolean") {
      throw new RuntimeError(
        'Operator "&&" requires boolean arguments. First argument is ' +
          left +
          "."
      );
    }

    // short circuit the expression
    if (!left) {
      return false;
    }

    var right = this._right.evaluate(feature);
    if (typeof right !== "boolean") {
      throw new RuntimeError(
        'Operator "&&" requires boolean arguments. Second argument is ' +
          right +
          "."
      );
    }

    return left && right;
  };

  Node$2.prototype._evaluatePlus = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (right instanceof Cartesian2 && left instanceof Cartesian2) {
      return Cartesian2.add(left, right, scratchStorage.getCartesian2());
    } else if (right instanceof Cartesian3 && left instanceof Cartesian3) {
      return Cartesian3.add(left, right, scratchStorage.getCartesian3());
    } else if (right instanceof Cartesian4 && left instanceof Cartesian4) {
      return Cartesian4.add(left, right, scratchStorage.getCartesian4());
    } else if (typeof left === "string" || typeof right === "string") {
      // If only one argument is a string the other argument calls its toString function.
      return left + right;
    } else if (typeof left === "number" && typeof right === "number") {
      return left + right;
    }

    throw new RuntimeError(
      'Operator "+" requires vector or number arguments of matching types, or at least one string argument. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateMinus = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (right instanceof Cartesian2 && left instanceof Cartesian2) {
      return Cartesian2.subtract(left, right, scratchStorage.getCartesian2());
    } else if (right instanceof Cartesian3 && left instanceof Cartesian3) {
      return Cartesian3.subtract(left, right, scratchStorage.getCartesian3());
    } else if (right instanceof Cartesian4 && left instanceof Cartesian4) {
      return Cartesian4.subtract(left, right, scratchStorage.getCartesian4());
    } else if (typeof left === "number" && typeof right === "number") {
      return left - right;
    }

    throw new RuntimeError(
      'Operator "-" requires vector or number arguments of matching types. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateTimes = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (right instanceof Cartesian2 && left instanceof Cartesian2) {
      return Cartesian2.multiplyComponents(
        left,
        right,
        scratchStorage.getCartesian2()
      );
    } else if (right instanceof Cartesian2 && typeof left === "number") {
      return Cartesian2.multiplyByScalar(
        right,
        left,
        scratchStorage.getCartesian2()
      );
    } else if (left instanceof Cartesian2 && typeof right === "number") {
      return Cartesian2.multiplyByScalar(
        left,
        right,
        scratchStorage.getCartesian2()
      );
    } else if (right instanceof Cartesian3 && left instanceof Cartesian3) {
      return Cartesian3.multiplyComponents(
        left,
        right,
        scratchStorage.getCartesian3()
      );
    } else if (right instanceof Cartesian3 && typeof left === "number") {
      return Cartesian3.multiplyByScalar(
        right,
        left,
        scratchStorage.getCartesian3()
      );
    } else if (left instanceof Cartesian3 && typeof right === "number") {
      return Cartesian3.multiplyByScalar(
        left,
        right,
        scratchStorage.getCartesian3()
      );
    } else if (right instanceof Cartesian4 && left instanceof Cartesian4) {
      return Cartesian4.multiplyComponents(
        left,
        right,
        scratchStorage.getCartesian4()
      );
    } else if (right instanceof Cartesian4 && typeof left === "number") {
      return Cartesian4.multiplyByScalar(
        right,
        left,
        scratchStorage.getCartesian4()
      );
    } else if (left instanceof Cartesian4 && typeof right === "number") {
      return Cartesian4.multiplyByScalar(
        left,
        right,
        scratchStorage.getCartesian4()
      );
    } else if (typeof left === "number" && typeof right === "number") {
      return left * right;
    }

    throw new RuntimeError(
      'Operator "*" requires vector or number arguments. If both arguments are vectors they must be matching types. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateDivide = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (right instanceof Cartesian2 && left instanceof Cartesian2) {
      return Cartesian2.divideComponents(
        left,
        right,
        scratchStorage.getCartesian2()
      );
    } else if (left instanceof Cartesian2 && typeof right === "number") {
      return Cartesian2.divideByScalar(
        left,
        right,
        scratchStorage.getCartesian2()
      );
    } else if (right instanceof Cartesian3 && left instanceof Cartesian3) {
      return Cartesian3.divideComponents(
        left,
        right,
        scratchStorage.getCartesian3()
      );
    } else if (left instanceof Cartesian3 && typeof right === "number") {
      return Cartesian3.divideByScalar(
        left,
        right,
        scratchStorage.getCartesian3()
      );
    } else if (right instanceof Cartesian4 && left instanceof Cartesian4) {
      return Cartesian4.divideComponents(
        left,
        right,
        scratchStorage.getCartesian4()
      );
    } else if (left instanceof Cartesian4 && typeof right === "number") {
      return Cartesian4.divideByScalar(
        left,
        right,
        scratchStorage.getCartesian4()
      );
    } else if (typeof left === "number" && typeof right === "number") {
      return left / right;
    }

    throw new RuntimeError(
      'Operator "/" requires vector or number arguments of matching types, or a number as the second argument. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateMod = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (right instanceof Cartesian2 && left instanceof Cartesian2) {
      return Cartesian2.fromElements(
        left.x % right.x,
        left.y % right.y,
        scratchStorage.getCartesian2()
      );
    } else if (right instanceof Cartesian3 && left instanceof Cartesian3) {
      return Cartesian3.fromElements(
        left.x % right.x,
        left.y % right.y,
        left.z % right.z,
        scratchStorage.getCartesian3()
      );
    } else if (right instanceof Cartesian4 && left instanceof Cartesian4) {
      return Cartesian4.fromElements(
        left.x % right.x,
        left.y % right.y,
        left.z % right.z,
        left.w % right.w,
        scratchStorage.getCartesian4()
      );
    } else if (typeof left === "number" && typeof right === "number") {
      return left % right;
    }

    throw new RuntimeError(
      'Operator "%" requires vector or number arguments of matching types. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateEqualsStrict = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (
      (right instanceof Cartesian2 && left instanceof Cartesian2) ||
      (right instanceof Cartesian3 && left instanceof Cartesian3) ||
      (right instanceof Cartesian4 && left instanceof Cartesian4)
    ) {
      return left.equals(right);
    }
    return left === right;
  };

  Node$2.prototype._evaluateNotEqualsStrict = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);
    if (
      (right instanceof Cartesian2 && left instanceof Cartesian2) ||
      (right instanceof Cartesian3 && left instanceof Cartesian3) ||
      (right instanceof Cartesian4 && left instanceof Cartesian4)
    ) {
      return !left.equals(right);
    }
    return left !== right;
  };

  Node$2.prototype._evaluateConditional = function (feature) {
    var test = this._test.evaluate(feature);

    if (typeof test !== "boolean") {
      throw new RuntimeError(
        "Conditional argument of conditional expression must be a boolean. Argument is " +
          test +
          "."
      );
    }

    if (test) {
      return this._left.evaluate(feature);
    }
    return this._right.evaluate(feature);
  };

  Node$2.prototype._evaluateNaN = function (feature) {
    return isNaN(this._left.evaluate(feature));
  };

  Node$2.prototype._evaluateIsFinite = function (feature) {
    return isFinite(this._left.evaluate(feature));
  };

  Node$2.prototype._evaluateIsExactClass = function (feature) {
    if (defined(feature)) {
      return feature.isExactClass(this._left.evaluate(feature));
    }
    return false;
  };

  Node$2.prototype._evaluateIsClass = function (feature) {
    if (defined(feature)) {
      return feature.isClass(this._left.evaluate(feature));
    }
    return false;
  };

  Node$2.prototype._evaluateGetExactClassName = function (feature) {
    if (defined(feature)) {
      return feature.getExactClassName();
    }
  };

  Node$2.prototype._evaluateBooleanConversion = function (feature) {
    return Boolean(this._left.evaluate(feature));
  };

  Node$2.prototype._evaluateNumberConversion = function (feature) {
    return Number(this._left.evaluate(feature));
  };

  Node$2.prototype._evaluateStringConversion = function (feature) {
    return String(this._left.evaluate(feature));
  };

  Node$2.prototype._evaluateRegExp = function (feature) {
    var pattern = this._value.evaluate(feature);
    var flags = "";

    if (defined(this._left)) {
      flags = this._left.evaluate(feature);
    }

    var exp;
    try {
      exp = new RegExp(pattern, flags);
    } catch (e) {
      throw new RuntimeError(e);
    }
    return exp;
  };

  Node$2.prototype._evaluateRegExpTest = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (!(left instanceof RegExp && typeof right === "string")) {
      throw new RuntimeError(
        "RegExp.test requires the first argument to be a RegExp and the second argument to be a string. Arguments are " +
          left +
          " and " +
          right +
          "."
      );
    }

    return left.test(right);
  };

  Node$2.prototype._evaluateRegExpMatch = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (left instanceof RegExp && typeof right === "string") {
      return left.test(right);
    } else if (right instanceof RegExp && typeof left === "string") {
      return right.test(left);
    }

    throw new RuntimeError(
      'Operator "=~" requires one RegExp argument and one string argument. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateRegExpNotMatch = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (left instanceof RegExp && typeof right === "string") {
      return !left.test(right);
    } else if (right instanceof RegExp && typeof left === "string") {
      return !right.test(left);
    }

    throw new RuntimeError(
      'Operator "!~" requires one RegExp argument and one string argument. Arguments are ' +
        left +
        " and " +
        right +
        "."
    );
  };

  Node$2.prototype._evaluateRegExpExec = function (feature) {
    var left = this._left.evaluate(feature);
    var right = this._right.evaluate(feature);

    if (!(left instanceof RegExp && typeof right === "string")) {
      throw new RuntimeError(
        "RegExp.exec requires the first argument to be a RegExp and the second argument to be a string. Arguments are " +
          left +
          " and " +
          right +
          "."
      );
    }

    var exec = left.exec(right);
    if (!defined(exec)) {
      return null;
    }
    return exec[1];
  };

  Node$2.prototype._evaluateToString = function (feature) {
    var left = this._left.evaluate(feature);
    if (
      left instanceof RegExp ||
      left instanceof Cartesian2 ||
      left instanceof Cartesian3 ||
      left instanceof Cartesian4
    ) {
      return String(left);
    }

    throw new RuntimeError('Unexpected function call "' + this._value + '".');
  };

  function convertHSLToRGB(ast) {
    // Check if the color contains any nested expressions to see if the color can be converted here.
    // E.g. "hsl(0.9, 0.6, 0.7)" is able to convert directly to rgb, "hsl(0.9, 0.6, ${Height})" is not.
    var channels = ast._left;
    var length = channels.length;
    for (var i = 0; i < length; ++i) {
      if (channels[i]._type !== ExpressionNodeType$1.LITERAL_NUMBER) {
        return undefined;
      }
    }
    var h = channels[0]._value;
    var s = channels[1]._value;
    var l = channels[2]._value;
    var a = length === 4 ? channels[3]._value : 1.0;
    return Color.fromHsl(h, s, l, a, scratchColor$2);
  }

  function convertRGBToColor(ast) {
    // Check if the color contains any nested expressions to see if the color can be converted here.
    // E.g. "rgb(255, 255, 255)" is able to convert directly to Color, "rgb(255, 255, ${Height})" is not.
    var channels = ast._left;
    var length = channels.length;
    for (var i = 0; i < length; ++i) {
      if (channels[i]._type !== ExpressionNodeType$1.LITERAL_NUMBER) {
        return undefined;
      }
    }
    var color = scratchColor$2;
    color.red = channels[0]._value / 255.0;
    color.green = channels[1]._value / 255.0;
    color.blue = channels[2]._value / 255.0;
    color.alpha = length === 4 ? channels[3]._value : 1.0;
    return color;
  }

  function numberToString(number) {
    if (number % 1 === 0) {
      // Add a .0 to whole numbers
      return number.toFixed(1);
    }

    return number.toString();
  }

  function colorToVec3(color) {
    var r = numberToString(color.red);
    var g = numberToString(color.green);
    var b = numberToString(color.blue);
    return "vec3(" + r + ", " + g + ", " + b + ")";
  }

  function colorToVec4(color) {
    var r = numberToString(color.red);
    var g = numberToString(color.green);
    var b = numberToString(color.blue);
    var a = numberToString(color.alpha);
    return "vec4(" + r + ", " + g + ", " + b + ", " + a + ")";
  }

  function getExpressionArray(array, propertyNameMap, shaderState, parent) {
    var length = array.length;
    var expressions = new Array(length);
    for (var i = 0; i < length; ++i) {
      expressions[i] = array[i].getShaderExpression(
        propertyNameMap,
        shaderState,
        parent
      );
    }
    return expressions;
  }

  function getVariableName(variableName, propertyNameMap) {
    if (!defined(propertyNameMap[variableName])) {
      throw new RuntimeError(
        'Style references a property "' +
          variableName +
          '" that does not exist or is not styleable.'
      );
    }

    return propertyNameMap[variableName];
  }

  var nullSentinel = "czm_infinity"; // null just needs to be some sentinel value that will cause "[expression] === null" to be false in nearly all cases. GLSL doesn't have a NaN constant so use czm_infinity.

  Node$2.prototype.getShaderExpression = function (
    propertyNameMap,
    shaderState,
    parent
  ) {
    var color;
    var left;
    var right;
    var test;

    var type = this._type;
    var value = this._value;

    if (defined(this._left)) {
      if (Array.isArray(this._left)) {
        // Left can be an array if the type is LITERAL_COLOR or LITERAL_VECTOR
        left = getExpressionArray(this._left, propertyNameMap, shaderState, this);
      } else {
        left = this._left.getShaderExpression(propertyNameMap, shaderState, this);
      }
    }

    if (defined(this._right)) {
      right = this._right.getShaderExpression(propertyNameMap, shaderState, this);
    }

    if (defined(this._test)) {
      test = this._test.getShaderExpression(propertyNameMap, shaderState, this);
    }

    if (Array.isArray(this._value)) {
      // For ARRAY type
      value = getExpressionArray(this._value, propertyNameMap, shaderState, this);
    }

    switch (type) {
      case ExpressionNodeType$1.VARIABLE:
        if (checkFeature(this)) {
          return undefined;
        }
        return getVariableName(value, propertyNameMap);
      case ExpressionNodeType$1.UNARY:
        // Supported types: +, -, !, Boolean, Number
        if (value === "Boolean") {
          return "bool(" + left + ")";
        } else if (value === "Number") {
          return "float(" + left + ")";
        } else if (value === "round") {
          return "floor(" + left + " + 0.5)";
        } else if (defined(unaryFunctions[value])) {
          return value + "(" + left + ")";
        } else if (value === "isNaN") {
          // In GLSL 2.0 use isnan instead
          return "(" + left + " != " + left + ")";
        } else if (value === "isFinite") {
          // In GLSL 2.0 use isinf instead. GLSL doesn't have an infinity constant so use czm_infinity which is an arbitrarily big enough number.
          return "(abs(" + left + ") < czm_infinity)";
        } else if (
          value === "String" ||
          value === "isExactClass" ||
          value === "isClass" ||
          value === "getExactClassName"
        ) {
          throw new RuntimeError(
            'Error generating style shader: "' + value + '" is not supported.'
          );
        }
        return value + left;
      case ExpressionNodeType$1.BINARY:
        // Supported types: ||, &&, ===, !==, <, >, <=, >=, +, -, *, /, %
        if (value === "%") {
          return "mod(" + left + ", " + right + ")";
        } else if (value === "===") {
          return "(" + left + " == " + right + ")";
        } else if (value === "!==") {
          return "(" + left + " != " + right + ")";
        } else if (value === "atan2") {
          return "atan(" + left + ", " + right + ")";
        } else if (defined(binaryFunctions[value])) {
          return value + "(" + left + ", " + right + ")";
        }
        return "(" + left + " " + value + " " + right + ")";
      case ExpressionNodeType$1.TERNARY:
        if (defined(ternaryFunctions[value])) {
          return value + "(" + left + ", " + right + ", " + test + ")";
        }
        break;
      case ExpressionNodeType$1.CONDITIONAL:
        return "(" + test + " ? " + left + " : " + right + ")";
      case ExpressionNodeType$1.MEMBER:
        if (checkFeature(this._left)) {
          return getVariableName(right, propertyNameMap);
        }
        // This is intended for accessing the components of vector properties. String members aren't supported.
        // Check for 0.0 rather than 0 because all numbers are previously converted to decimals.
        if (right === "r" || right === "x" || right === "0.0") {
          return left + "[0]";
        } else if (right === "g" || right === "y" || right === "1.0") {
          return left + "[1]";
        } else if (right === "b" || right === "z" || right === "2.0") {
          return left + "[2]";
        } else if (right === "a" || right === "w" || right === "3.0") {
          return left + "[3]";
        }
        return left + "[int(" + right + ")]";
      case ExpressionNodeType$1.FUNCTION_CALL:
        throw new RuntimeError(
          'Error generating style shader: "' + value + '" is not supported.'
        );
      case ExpressionNodeType$1.ARRAY:
        if (value.length === 4) {
          return (
            "vec4(" +
            value[0] +
            ", " +
            value[1] +
            ", " +
            value[2] +
            ", " +
            value[3] +
            ")"
          );
        } else if (value.length === 3) {
          return "vec3(" + value[0] + ", " + value[1] + ", " + value[2] + ")";
        } else if (value.length === 2) {
          return "vec2(" + value[0] + ", " + value[1] + ")";
        }
        throw new RuntimeError(
          "Error generating style shader: Invalid array length. Array length should be 2, 3, or 4."
        );
      case ExpressionNodeType$1.REGEX:
        throw new RuntimeError(
          "Error generating style shader: Regular expressions are not supported."
        );
      case ExpressionNodeType$1.VARIABLE_IN_STRING:
        throw new RuntimeError(
          "Error generating style shader: Converting a variable to a string is not supported."
        );
      case ExpressionNodeType$1.LITERAL_NULL:
        return nullSentinel;
      case ExpressionNodeType$1.LITERAL_BOOLEAN:
        return value ? "true" : "false";
      case ExpressionNodeType$1.LITERAL_NUMBER:
        return numberToString(value);
      case ExpressionNodeType$1.LITERAL_STRING:
        if (defined(parent) && parent._type === ExpressionNodeType$1.MEMBER) {
          if (
            value === "r" ||
            value === "g" ||
            value === "b" ||
            value === "a" ||
            value === "x" ||
            value === "y" ||
            value === "z" ||
            value === "w" ||
            checkFeature(parent._left)
          ) {
            return value;
          }
        }
        // Check for css color strings
        color = Color.fromCssColorString(value, scratchColor$2);
        if (defined(color)) {
          return colorToVec3(color);
        }
        throw new RuntimeError(
          "Error generating style shader: String literals are not supported."
        );
      case ExpressionNodeType$1.LITERAL_COLOR:
        var args = left;
        if (value === "color") {
          if (!defined(args)) {
            return "vec4(1.0)";
          } else if (args.length > 1) {
            var rgb = args[0];
            var alpha = args[1];
            if (alpha !== "1.0") {
              shaderState.translucent = true;
            }
            return "vec4(" + rgb + ", " + alpha + ")";
          }
          return "vec4(" + args[0] + ", 1.0)";
        } else if (value === "rgb") {
          color = convertRGBToColor(this);
          if (defined(color)) {
            return colorToVec4(color);
          }
          return (
            "vec4(" +
            args[0] +
            " / 255.0, " +
            args[1] +
            " / 255.0, " +
            args[2] +
            " / 255.0, 1.0)"
          );
        } else if (value === "rgba") {
          if (args[3] !== "1.0") {
            shaderState.translucent = true;
          }
          color = convertRGBToColor(this);
          if (defined(color)) {
            return colorToVec4(color);
          }
          return (
            "vec4(" +
            args[0] +
            " / 255.0, " +
            args[1] +
            " / 255.0, " +
            args[2] +
            " / 255.0, " +
            args[3] +
            ")"
          );
        } else if (value === "hsl") {
          color = convertHSLToRGB(this);
          if (defined(color)) {
            return colorToVec4(color);
          }
          return (
            "vec4(czm_HSLToRGB(vec3(" +
            args[0] +
            ", " +
            args[1] +
            ", " +
            args[2] +
            ")), 1.0)"
          );
        } else if (value === "hsla") {
          color = convertHSLToRGB(this);
          if (defined(color)) {
            if (color.alpha !== 1.0) {
              shaderState.translucent = true;
            }
            return colorToVec4(color);
          }
          if (args[3] !== "1.0") {
            shaderState.translucent = true;
          }
          return (
            "vec4(czm_HSLToRGB(vec3(" +
            args[0] +
            ", " +
            args[1] +
            ", " +
            args[2] +
            ")), " +
            args[3] +
            ")"
          );
        }
        break;
      case ExpressionNodeType$1.LITERAL_VECTOR:
        //>>includeStart('debug', pragmas.debug);
        if (!defined(left)) {
          throw new DeveloperError(
            "left should always be defined for type ExpressionNodeType.LITERAL_VECTOR"
          );
        }
        //>>includeEnd('debug');
        var length = left.length;
        var vectorExpression = value + "(";
        for (var i = 0; i < length; ++i) {
          vectorExpression += left[i];
          if (i < length - 1) {
            vectorExpression += ", ";
          }
        }
        vectorExpression += ")";
        return vectorExpression;
      case ExpressionNodeType$1.LITERAL_REGEX:
        throw new RuntimeError(
          "Error generating style shader: Regular expressions are not supported."
        );
      case ExpressionNodeType$1.LITERAL_UNDEFINED:
        return nullSentinel;
      case ExpressionNodeType$1.BUILTIN_VARIABLE:
        if (value === "tiles3d_tileset_time") {
          return "u_time";
        }
    }
  };

  /**
   * Creates a batch of classification meshes.
   *
   * @alias Vector3DTilePrimitive
   * @constructor
   *
   * @param {Object} options An object with following properties:
   * @param {Float32Array} options.positions The positions of the meshes.
   * @param {Uint16Array|Uint32Array} options.indices The indices of the triangulated meshes. The indices must be contiguous so that
   * the indices for mesh n are in [i, i + indexCounts[n]] where i = sum{indexCounts[0], indexCounts[n - 1]}.
   * @param {Uint32Array} options.indexCounts The number of indices for each mesh.
   * @param {Uint32Array} options.indexOffsets The offset into the index buffer for each mesh.
   * @param {Vector3DTileBatch[]} options.batchedIndices The index offset and count for each batch with the same color.
   * @param {Cartesian3} [options.center=Cartesian3.ZERO] The RTC center.
   * @param {Cesium3DTileBatchTable} options.batchTable The batch table for the tile containing the batched meshes.
   * @param {Uint16Array} options.batchIds The batch ids for each mesh.
   * @param {Uint16Array} options.vertexBatchIds The batch id for each vertex.
   * @param {BoundingSphere} options.boundingVolume The bounding volume for the entire batch of meshes.
   * @param {BoundingSphere[]} options.boundingVolumes The bounding volume for each mesh.
   * @param {ClassificationType} [options.classificationType] What this tile will classify.
   *
   * @private
   */
  function Vector3DTilePrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._batchTable = options.batchTable;
    this._batchIds = options.batchIds;

    // These arrays are released after VAO creation.
    this._positions = options.positions;
    this._vertexBatchIds = options.vertexBatchIds;

    // These arrays are kept for re-batching indices based on colors.
    // If WebGL 2 is supported, indices will be released and re-batching uses buffer-to-buffer copies.
    this._indices = options.indices;
    this._indexCounts = options.indexCounts;
    this._indexOffsets = options.indexOffsets;
    this._batchedIndices = options.batchedIndices;

    this._boundingVolume = options.boundingVolume;
    this._boundingVolumes = options.boundingVolumes;

    this._center = defaultValue(options.center, Cartesian3.ZERO);

    this._va = undefined;
    this._sp = undefined;
    this._spStencil = undefined;
    this._spPick = undefined;
    this._uniformMap = undefined;

    // Only used with WebGL 2 to ping-pong ibos after copy.
    this._vaSwap = undefined;

    this._rsStencilDepthPass = undefined;
    this._rsStencilDepthPass3DTiles = undefined;
    this._rsColorPass = undefined;
    this._rsPickPass = undefined;
    this._rsWireframe = undefined;

    this._commands = [];
    this._commandsIgnoreShow = [];
    this._pickCommands = [];

    this._constantColor = Color.clone(Color.WHITE);
    this._highlightColor = this._constantColor;

    this._batchDirty = true;
    this._pickCommandsDirty = true;
    this._framesSinceLastRebatch = 0;

    this._updatingAllCommands = false;

    this._trianglesLength = this._indices.length / 3;
    this._geometryByteLength =
      this._indices.byteLength +
      this._positions.byteLength +
      this._vertexBatchIds.byteLength;

    /**
     * Draw the wireframe of the classification meshes.
     * @type {Boolean}
     * @default false
     */
    this.debugWireframe = false;
    this._debugWireframe = this.debugWireframe;
    this._wireframeDirty = false;

    /**
     * Forces a re-batch instead of waiting after a number of frames have been rendered. For testing only.
     * @type {Boolean}
     * @default false
     */
    this.forceRebatch = false;

    /**
     * What this tile will classify.
     * @type {ClassificationType}
     * @default ClassificationType.BOTH
     */
    this.classificationType = defaultValue(
      options.classificationType,
      ClassificationType$1.BOTH
    );

    // Hidden options
    this._vertexShaderSource = options._vertexShaderSource;
    this._fragmentShaderSource = options._fragmentShaderSource;
    this._attributeLocations = options._attributeLocations;
    this._uniformMap = options._uniformMap;
    this._pickId = options._pickId;
    this._modelMatrix = options._modelMatrix;
    this._boundingSphere = options._boundingSphere;

    this._batchIdLookUp = {};

    var length = this._batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = this._batchIds[i];
      this._batchIdLookUp[batchId] = i;
    }
  }

  Object.defineProperties(Vector3DTilePrimitive.prototype, {
    /**
     * Gets the number of triangles.
     *
     * @memberof Vector3DTilePrimitive.prototype
     *
     * @type {Number}
     * @readonly
     */
    trianglesLength: {
      get: function () {
        return this._trianglesLength;
      },
    },

    /**
     * Gets the geometry memory in bytes.
     *
     * @memberof Vector3DTilePrimitive.prototype
     *
     * @type {Number}
     * @readonly
     */
    geometryByteLength: {
      get: function () {
        return this._geometryByteLength;
      },
    },
  });

  var defaultAttributeLocations = {
    position: 0,
    a_batchId: 1,
  };

  function createVertexArray$1(primitive, context) {
    if (defined(primitive._va)) {
      return;
    }

    var positionBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: primitive._positions,
      usage: BufferUsage$1.STATIC_DRAW,
    });
    var idBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: primitive._vertexBatchIds,
      usage: BufferUsage$1.STATIC_DRAW,
    });
    var indexBuffer = Buffer$1.createIndexBuffer({
      context: context,
      typedArray: primitive._indices,
      usage: BufferUsage$1.DYNAMIC_DRAW,
      indexDatatype:
        primitive._indices.BYTES_PER_ELEMENT === 2
          ? IndexDatatype$1.UNSIGNED_SHORT
          : IndexDatatype$1.UNSIGNED_INT,
    });

    var vertexAttributes = [
      {
        index: 0,
        vertexBuffer: positionBuffer,
        componentDatatype: ComponentDatatype$1.fromTypedArray(primitive._positions),
        componentsPerAttribute: 3,
      },
      {
        index: 1,
        vertexBuffer: idBuffer,
        componentDatatype: ComponentDatatype$1.fromTypedArray(
          primitive._vertexBatchIds
        ),
        componentsPerAttribute: 1,
      },
    ];

    primitive._va = new VertexArray({
      context: context,
      attributes: vertexAttributes,
      indexBuffer: indexBuffer,
    });

    if (context.webgl2) {
      primitive._vaSwap = new VertexArray({
        context: context,
        attributes: vertexAttributes,
        indexBuffer: Buffer$1.createIndexBuffer({
          context: context,
          sizeInBytes: indexBuffer.sizeInBytes,
          usage: BufferUsage$1.DYNAMIC_DRAW,
          indexDatatype: indexBuffer.indexDatatype,
        }),
      });
    }

    primitive._batchedPositions = undefined;
    primitive._transferrableBatchIds = undefined;
    primitive._vertexBatchIds = undefined;
    primitive._verticesPromise = undefined;
  }

  function createShaders(primitive, context) {
    if (defined(primitive._sp)) {
      return;
    }

    var batchTable = primitive._batchTable;
    var attributeLocations = defaultValue(
      primitive._attributeLocations,
      defaultAttributeLocations
    );

    var pickId = primitive._pickId;
    var vertexShaderSource = primitive._vertexShaderSource;
    var fragmentShaderSource = primitive._fragmentShaderSource;
    if (defined(vertexShaderSource)) {
      primitive._sp = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: vertexShaderSource,
        fragmentShaderSource: fragmentShaderSource,
        attributeLocations: attributeLocations,
      });
      primitive._spStencil = primitive._sp;

      fragmentShaderSource = ShaderSource.replaceMain(
        fragmentShaderSource,
        "czm_non_pick_main"
      );
      fragmentShaderSource =
        fragmentShaderSource +
        "void main() \n" +
        "{ \n" +
        "    czm_non_pick_main(); \n" +
        "    gl_FragColor = " +
        pickId +
        "; \n" +
        "} \n";
      primitive._spPick = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: vertexShaderSource,
        fragmentShaderSource: fragmentShaderSource,
        attributeLocations: attributeLocations,
      });
      return;
    }

    var vsSource = batchTable.getVertexShaderCallback(
      false,
      "a_batchId",
      undefined
    )(VectorTileVS);
    var fsSource = batchTable.getFragmentShaderCallback()(
      ShadowVolumeFS,
      false,
      undefined
    );

    pickId = batchTable.getPickId();

    var vs = new ShaderSource({
      sources: [vsSource],
    });
    var fs = new ShaderSource({
      defines: ["VECTOR_TILE"],
      sources: [fsSource],
    });

    primitive._sp = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations,
    });

    vs = new ShaderSource({
      sources: [VectorTileVS],
    });
    fs = new ShaderSource({
      defines: ["VECTOR_TILE"],
      sources: [ShadowVolumeFS],
    });

    primitive._spStencil = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations,
    });

    fsSource = ShaderSource.replaceMain(fsSource, "czm_non_pick_main");
    fsSource =
      fsSource +
      "\n" +
      "void main() \n" +
      "{ \n" +
      "    czm_non_pick_main(); \n" +
      "    gl_FragColor = " +
      pickId +
      "; \n" +
      "} \n";

    var pickVS = new ShaderSource({
      sources: [vsSource],
    });
    var pickFS = new ShaderSource({
      defines: ["VECTOR_TILE"],
      sources: [fsSource],
    });
    primitive._spPick = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: pickVS,
      fragmentShaderSource: pickFS,
      attributeLocations: attributeLocations,
    });
  }

  function getStencilDepthRenderState$1(mask3DTiles) {
    var stencilFunction = mask3DTiles
      ? StencilFunction$1.EQUAL
      : StencilFunction$1.ALWAYS;
    return {
      colorMask: {
        red: false,
        green: false,
        blue: false,
        alpha: false,
      },
      stencilTest: {
        enabled: true,
        frontFunction: stencilFunction,
        frontOperation: {
          fail: StencilOperation$1.KEEP,
          zFail: StencilOperation$1.DECREMENT_WRAP,
          zPass: StencilOperation$1.KEEP,
        },
        backFunction: stencilFunction,
        backOperation: {
          fail: StencilOperation$1.KEEP,
          zFail: StencilOperation$1.INCREMENT_WRAP,
          zPass: StencilOperation$1.KEEP,
        },
        reference: StencilConstants$1.CESIUM_3D_TILE_MASK,
        mask: StencilConstants$1.CESIUM_3D_TILE_MASK,
      },
      stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
      depthTest: {
        enabled: true,
        func: DepthFunction$1.LESS_OR_EQUAL,
      },
      depthMask: false,
    };
  }

  var colorRenderState = {
    stencilTest: {
      enabled: true,
      frontFunction: StencilFunction$1.NOT_EQUAL,
      frontOperation: {
        fail: StencilOperation$1.ZERO,
        zFail: StencilOperation$1.ZERO,
        zPass: StencilOperation$1.ZERO,
      },
      backFunction: StencilFunction$1.NOT_EQUAL,
      backOperation: {
        fail: StencilOperation$1.ZERO,
        zFail: StencilOperation$1.ZERO,
        zPass: StencilOperation$1.ZERO,
      },
      reference: 0,
      mask: StencilConstants$1.CLASSIFICATION_MASK,
    },
    stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
    depthTest: {
      enabled: false,
    },
    depthMask: false,
    blending: BlendingState$1.ALPHA_BLEND,
  };

  var pickRenderState$1 = {
    stencilTest: {
      enabled: true,
      frontFunction: StencilFunction$1.NOT_EQUAL,
      frontOperation: {
        fail: StencilOperation$1.ZERO,
        zFail: StencilOperation$1.ZERO,
        zPass: StencilOperation$1.ZERO,
      },
      backFunction: StencilFunction$1.NOT_EQUAL,
      backOperation: {
        fail: StencilOperation$1.ZERO,
        zFail: StencilOperation$1.ZERO,
        zPass: StencilOperation$1.ZERO,
      },
      reference: 0,
      mask: StencilConstants$1.CLASSIFICATION_MASK,
    },
    stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
    depthTest: {
      enabled: false,
    },
    depthMask: false,
  };

  function createRenderStates$2(primitive) {
    if (defined(primitive._rsStencilDepthPass)) {
      return;
    }

    primitive._rsStencilDepthPass = RenderState.fromCache(
      getStencilDepthRenderState$1(false)
    );
    primitive._rsStencilDepthPass3DTiles = RenderState.fromCache(
      getStencilDepthRenderState$1(true)
    );
    primitive._rsColorPass = RenderState.fromCache(colorRenderState);
    primitive._rsPickPass = RenderState.fromCache(pickRenderState$1);
  }

  var modifiedModelViewScratch$1 = new Matrix4();
  var rtcScratch$1 = new Cartesian3();

  function createUniformMap(primitive, context) {
    if (defined(primitive._uniformMap)) {
      return;
    }

    var uniformMap = {
      u_modifiedModelViewProjection: function () {
        var viewMatrix = context.uniformState.view;
        var projectionMatrix = context.uniformState.projection;
        Matrix4.clone(viewMatrix, modifiedModelViewScratch$1);
        Matrix4.multiplyByPoint(
          modifiedModelViewScratch$1,
          primitive._center,
          rtcScratch$1
        );
        Matrix4.setTranslation(
          modifiedModelViewScratch$1,
          rtcScratch$1,
          modifiedModelViewScratch$1
        );
        Matrix4.multiply(
          projectionMatrix,
          modifiedModelViewScratch$1,
          modifiedModelViewScratch$1
        );
        return modifiedModelViewScratch$1;
      },
      u_highlightColor: function () {
        return primitive._highlightColor;
      },
    };

    primitive._uniformMap = primitive._batchTable.getUniformMapCallback()(
      uniformMap
    );
  }

  function copyIndicesCPU(
    indices,
    newIndices,
    currentOffset,
    offsets,
    counts,
    batchIds,
    batchIdLookUp
  ) {
    var sizeInBytes = indices.constructor.BYTES_PER_ELEMENT;

    var batchedIdsLength = batchIds.length;
    for (var j = 0; j < batchedIdsLength; ++j) {
      var batchedId = batchIds[j];
      var index = batchIdLookUp[batchedId];
      var offset = offsets[index];
      var count = counts[index];

      var subarray = new indices.constructor(
        indices.buffer,
        sizeInBytes * offset,
        count
      );
      newIndices.set(subarray, currentOffset);

      offsets[index] = currentOffset;
      currentOffset += count;
    }

    return currentOffset;
  }

  function rebatchCPU(primitive, batchedIndices) {
    var indices = primitive._indices;
    var indexOffsets = primitive._indexOffsets;
    var indexCounts = primitive._indexCounts;
    var batchIdLookUp = primitive._batchIdLookUp;

    var newIndices = new indices.constructor(indices.length);

    var current = batchedIndices.pop();
    var newBatchedIndices = [current];

    var currentOffset = copyIndicesCPU(
      indices,
      newIndices,
      0,
      indexOffsets,
      indexCounts,
      current.batchIds,
      batchIdLookUp
    );

    current.offset = 0;
    current.count = currentOffset;

    while (batchedIndices.length > 0) {
      var next = batchedIndices.pop();
      if (Color.equals(next.color, current.color)) {
        currentOffset = copyIndicesCPU(
          indices,
          newIndices,
          currentOffset,
          indexOffsets,
          indexCounts,
          next.batchIds,
          batchIdLookUp
        );
        current.batchIds = current.batchIds.concat(next.batchIds);
        current.count = currentOffset - current.offset;
      } else {
        var offset = currentOffset;
        currentOffset = copyIndicesCPU(
          indices,
          newIndices,
          currentOffset,
          indexOffsets,
          indexCounts,
          next.batchIds,
          batchIdLookUp
        );

        next.offset = offset;
        next.count = currentOffset - offset;
        newBatchedIndices.push(next);
        current = next;
      }
    }

    primitive._va.indexBuffer.copyFromArrayView(newIndices);

    primitive._indices = newIndices;
    primitive._batchedIndices = newBatchedIndices;
  }

  function copyIndicesGPU(
    readBuffer,
    writeBuffer,
    currentOffset,
    offsets,
    counts,
    batchIds,
    batchIdLookUp
  ) {
    var sizeInBytes = readBuffer.bytesPerIndex;

    var batchedIdsLength = batchIds.length;
    for (var j = 0; j < batchedIdsLength; ++j) {
      var batchedId = batchIds[j];
      var index = batchIdLookUp[batchedId];
      var offset = offsets[index];
      var count = counts[index];

      writeBuffer.copyFromBuffer(
        readBuffer,
        offset * sizeInBytes,
        currentOffset * sizeInBytes,
        count * sizeInBytes
      );

      offsets[index] = currentOffset;
      currentOffset += count;
    }

    return currentOffset;
  }

  function rebatchGPU(primitive, batchedIndices) {
    var indexOffsets = primitive._indexOffsets;
    var indexCounts = primitive._indexCounts;
    var batchIdLookUp = primitive._batchIdLookUp;

    var current = batchedIndices.pop();
    var newBatchedIndices = [current];

    var readBuffer = primitive._va.indexBuffer;
    var writeBuffer = primitive._vaSwap.indexBuffer;

    var currentOffset = copyIndicesGPU(
      readBuffer,
      writeBuffer,
      0,
      indexOffsets,
      indexCounts,
      current.batchIds,
      batchIdLookUp
    );

    current.offset = 0;
    current.count = currentOffset;

    while (batchedIndices.length > 0) {
      var next = batchedIndices.pop();
      if (Color.equals(next.color, current.color)) {
        currentOffset = copyIndicesGPU(
          readBuffer,
          writeBuffer,
          currentOffset,
          indexOffsets,
          indexCounts,
          next.batchIds,
          batchIdLookUp
        );
        current.batchIds = current.batchIds.concat(next.batchIds);
        current.count = currentOffset - current.offset;
      } else {
        var offset = currentOffset;
        currentOffset = copyIndicesGPU(
          readBuffer,
          writeBuffer,
          currentOffset,
          indexOffsets,
          indexCounts,
          next.batchIds,
          batchIdLookUp
        );
        next.offset = offset;
        next.count = currentOffset - offset;
        newBatchedIndices.push(next);
        current = next;
      }
    }

    var temp = primitive._va;
    primitive._va = primitive._vaSwap;
    primitive._vaSwap = temp;

    primitive._batchedIndices = newBatchedIndices;
  }

  function compareColors(a, b) {
    return b.color.toRgba() - a.color.toRgba();
  }

  // PERFORMANCE_IDEA: For WebGL 2, we can use copyBufferSubData for buffer-to-buffer copies.
  // PERFORMANCE_IDEA: Not supported, but we could use glMultiDrawElements here.
  function rebatchCommands(primitive, context) {
    if (!primitive._batchDirty) {
      return false;
    }

    var batchedIndices = primitive._batchedIndices;
    var length = batchedIndices.length;

    var needToRebatch = false;
    var colorCounts = {};

    for (var i = 0; i < length; ++i) {
      var color = batchedIndices[i].color;
      var rgba = color.toRgba();
      if (defined(colorCounts[rgba])) {
        needToRebatch = true;
        break;
      } else {
        colorCounts[rgba] = true;
      }
    }

    if (!needToRebatch) {
      primitive._batchDirty = false;
      return false;
    }

    if (
      needToRebatch &&
      !primitive.forceRebatch &&
      primitive._framesSinceLastRebatch < 120
    ) {
      ++primitive._framesSinceLastRebatch;
      return;
    }

    batchedIndices.sort(compareColors);

    if (context.webgl2) {
      rebatchGPU(primitive, batchedIndices);
    } else {
      rebatchCPU(primitive, batchedIndices);
    }

    primitive._framesSinceLastRebatch = 0;
    primitive._batchDirty = false;
    primitive._pickCommandsDirty = true;
    primitive._wireframeDirty = true;
    return true;
  }

  function createColorCommands$1(primitive, context) {
    var needsRebatch = rebatchCommands(primitive, context);

    var commands = primitive._commands;
    var batchedIndices = primitive._batchedIndices;
    var length = batchedIndices.length;
    var commandsLength = length * 2;

    if (
      defined(commands) &&
      !needsRebatch &&
      commands.length === commandsLength
    ) {
      return;
    }

    commands.length = commandsLength;

    var vertexArray = primitive._va;
    var sp = primitive._sp;
    var modelMatrix = defaultValue(primitive._modelMatrix, Matrix4.IDENTITY);
    var uniformMap = primitive._uniformMap;
    var bv = primitive._boundingVolume;

    for (var j = 0; j < length; ++j) {
      var offset = batchedIndices[j].offset;
      var count = batchedIndices[j].count;

      var stencilDepthCommand = commands[j * 2];
      if (!defined(stencilDepthCommand)) {
        stencilDepthCommand = commands[j * 2] = new DrawCommand({
          owner: primitive,
        });
      }

      stencilDepthCommand.vertexArray = vertexArray;
      stencilDepthCommand.modelMatrix = modelMatrix;
      stencilDepthCommand.offset = offset;
      stencilDepthCommand.count = count;
      stencilDepthCommand.renderState = primitive._rsStencilDepthPass;
      stencilDepthCommand.shaderProgram = sp;
      stencilDepthCommand.uniformMap = uniformMap;
      stencilDepthCommand.boundingVolume = bv;
      stencilDepthCommand.cull = false;
      stencilDepthCommand.pass = Pass$1.TERRAIN_CLASSIFICATION;

      var stencilDepthDerivedCommand = DrawCommand.shallowClone(
        stencilDepthCommand,
        stencilDepthCommand.derivedCommands.tileset
      );
      stencilDepthDerivedCommand.renderState =
        primitive._rsStencilDepthPass3DTiles;
      stencilDepthDerivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      stencilDepthCommand.derivedCommands.tileset = stencilDepthDerivedCommand;

      var colorCommand = commands[j * 2 + 1];
      if (!defined(colorCommand)) {
        colorCommand = commands[j * 2 + 1] = new DrawCommand({
          owner: primitive,
        });
      }

      colorCommand.vertexArray = vertexArray;
      colorCommand.modelMatrix = modelMatrix;
      colorCommand.offset = offset;
      colorCommand.count = count;
      colorCommand.renderState = primitive._rsColorPass;
      colorCommand.shaderProgram = sp;
      colorCommand.uniformMap = uniformMap;
      colorCommand.boundingVolume = bv;
      colorCommand.cull = false;
      colorCommand.pass = Pass$1.TERRAIN_CLASSIFICATION;

      var colorDerivedCommand = DrawCommand.shallowClone(
        colorCommand,
        colorCommand.derivedCommands.tileset
      );
      colorDerivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      colorCommand.derivedCommands.tileset = colorDerivedCommand;
    }

    primitive._commandsDirty = true;
  }

  function createColorCommandsIgnoreShow(primitive, frameState) {
    if (
      primitive.classificationType === ClassificationType$1.TERRAIN ||
      !frameState.invertClassification ||
      (defined(primitive._commandsIgnoreShow) && !primitive._commandsDirty)
    ) {
      return;
    }

    var commands = primitive._commands;
    var commandsIgnoreShow = primitive._commandsIgnoreShow;
    var spStencil = primitive._spStencil;

    var commandsLength = commands.length;
    var length = (commandsIgnoreShow.length = commandsLength / 2);

    var commandIndex = 0;
    for (var j = 0; j < length; ++j) {
      var commandIgnoreShow = (commandsIgnoreShow[j] = DrawCommand.shallowClone(
        commands[commandIndex],
        commandsIgnoreShow[j]
      ));
      commandIgnoreShow.shaderProgram = spStencil;
      commandIgnoreShow.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW;

      commandIndex += 2;
    }

    primitive._commandsDirty = false;
  }

  function createPickCommands$1(primitive) {
    if (!primitive._pickCommandsDirty) {
      return;
    }

    var length = primitive._indexOffsets.length;
    var pickCommands = primitive._pickCommands;
    pickCommands.length = length * 2;

    var vertexArray = primitive._va;
    var spStencil = primitive._spStencil;
    var spPick = primitive._spPick;
    var modelMatrix = defaultValue(primitive._modelMatrix, Matrix4.IDENTITY);
    var uniformMap = primitive._uniformMap;

    for (var j = 0; j < length; ++j) {
      var offset = primitive._indexOffsets[j];
      var count = primitive._indexCounts[j];
      var bv = defined(primitive._boundingVolumes)
        ? primitive._boundingVolumes[j]
        : primitive.boundingVolume;

      var stencilDepthCommand = pickCommands[j * 2];
      if (!defined(stencilDepthCommand)) {
        stencilDepthCommand = pickCommands[j * 2] = new DrawCommand({
          owner: primitive,
          pickOnly: true,
        });
      }

      stencilDepthCommand.vertexArray = vertexArray;
      stencilDepthCommand.modelMatrix = modelMatrix;
      stencilDepthCommand.offset = offset;
      stencilDepthCommand.count = count;
      stencilDepthCommand.renderState = primitive._rsStencilDepthPass;
      stencilDepthCommand.shaderProgram = spStencil;
      stencilDepthCommand.uniformMap = uniformMap;
      stencilDepthCommand.boundingVolume = bv;
      stencilDepthCommand.pass = Pass$1.TERRAIN_CLASSIFICATION;

      var stencilDepthDerivedCommand = DrawCommand.shallowClone(
        stencilDepthCommand,
        stencilDepthCommand.derivedCommands.tileset
      );
      stencilDepthDerivedCommand.renderState =
        primitive._rsStencilDepthPass3DTiles;
      stencilDepthDerivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      stencilDepthCommand.derivedCommands.tileset = stencilDepthDerivedCommand;

      var colorCommand = pickCommands[j * 2 + 1];
      if (!defined(colorCommand)) {
        colorCommand = pickCommands[j * 2 + 1] = new DrawCommand({
          owner: primitive,
          pickOnly: true,
        });
      }

      colorCommand.vertexArray = vertexArray;
      colorCommand.modelMatrix = modelMatrix;
      colorCommand.offset = offset;
      colorCommand.count = count;
      colorCommand.renderState = primitive._rsPickPass;
      colorCommand.shaderProgram = spPick;
      colorCommand.uniformMap = uniformMap;
      colorCommand.boundingVolume = bv;
      colorCommand.pass = Pass$1.TERRAIN_CLASSIFICATION;

      var colorDerivedCommand = DrawCommand.shallowClone(
        colorCommand,
        colorCommand.derivedCommands.tileset
      );
      colorDerivedCommand.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
      colorCommand.derivedCommands.tileset = colorDerivedCommand;
    }

    primitive._pickCommandsDirty = false;
  }

  /**
   * Creates features for each mesh and places it at the batch id index of features.
   *
   * @param {Vector3DTileContent} content The vector tile content.
   * @param {Cesium3DTileFeature[]} features An array of features where the polygon features will be placed.
   */
  Vector3DTilePrimitive.prototype.createFeatures = function (content, features) {
    var batchIds = this._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      features[batchId] = new Cesium3DTileFeature(content, batchId);
    }
  };

  /**
   * Colors the entire tile when enabled is true. The resulting color will be (mesh batch table color * color).
   *
   * @param {Boolean} enabled Whether to enable debug coloring.
   * @param {Color} color The debug color.
   */
  Vector3DTilePrimitive.prototype.applyDebugSettings = function (enabled, color) {
    this._highlightColor = enabled ? color : this._constantColor;
  };

  function clearStyle(polygons, features) {
    polygons._updatingAllCommands = true;

    var batchIds = polygons._batchIds;
    var length = batchIds.length;
    var i;

    for (i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      var feature = features[batchId];

      feature.show = true;
      feature.color = Color.WHITE;
    }

    var batchedIndices = polygons._batchedIndices;
    length = batchedIndices.length;

    for (i = 0; i < length; ++i) {
      batchedIndices[i].color = Color.clone(Color.WHITE);
    }

    polygons._updatingAllCommands = false;
    polygons._batchDirty = true;
  }

  var scratchColor$3 = new Color();

  var DEFAULT_COLOR_VALUE$1 = Color.WHITE;
  var DEFAULT_SHOW_VALUE$1 = true;

  var complexExpressionReg = /\$/;

  /**
   * Apply a style to the content.
   *
   * @param {Cesium3DTileStyle} style The style.
   * @param {Cesium3DTileFeature[]} features The array of features.
   */
  Vector3DTilePrimitive.prototype.applyStyle = function (style, features) {
    if (!defined(style)) {
      clearStyle(this, features);
      return;
    }

    var colorExpression = style.color;
    var isSimpleStyle =
      colorExpression instanceof Expression &&
      !complexExpressionReg.test(colorExpression.expression);
    this._updatingAllCommands = isSimpleStyle;

    var batchIds = this._batchIds;
    var length = batchIds.length;
    var i;

    for (i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      var feature = features[batchId];

      feature.color = defined(style.color)
        ? style.color.evaluateColor(feature, scratchColor$3)
        : DEFAULT_COLOR_VALUE$1;
      feature.show = defined(style.show)
        ? style.show.evaluate(feature)
        : DEFAULT_SHOW_VALUE$1;
    }

    if (isSimpleStyle) {
      var batchedIndices = this._batchedIndices;
      length = batchedIndices.length;

      for (i = 0; i < length; ++i) {
        batchedIndices[i].color = Color.clone(Color.WHITE);
      }

      this._updatingAllCommands = false;
      this._batchDirty = true;
    }
  };

  /**
   * Call when updating the color of a mesh with batchId changes color. The meshes will need to be re-batched
   * on the next update.
   *
   * @param {Number} batchId The batch id of the meshes whose color has changed.
   * @param {Color} color The new polygon color.
   */
  Vector3DTilePrimitive.prototype.updateCommands = function (batchId, color) {
    if (this._updatingAllCommands) {
      return;
    }

    var batchIdLookUp = this._batchIdLookUp;
    var index = batchIdLookUp[batchId];
    if (!defined(index)) {
      return;
    }

    var indexOffsets = this._indexOffsets;
    var indexCounts = this._indexCounts;

    var offset = indexOffsets[index];
    var count = indexCounts[index];

    var batchedIndices = this._batchedIndices;
    var length = batchedIndices.length;

    var i;
    for (i = 0; i < length; ++i) {
      var batchedOffset = batchedIndices[i].offset;
      var batchedCount = batchedIndices[i].count;

      if (offset >= batchedOffset && offset < batchedOffset + batchedCount) {
        break;
      }
    }

    batchedIndices.push(
      new Vector3DTileBatch({
        color: Color.clone(color),
        offset: offset,
        count: count,
        batchIds: [batchId],
      })
    );

    var startIds = [];
    var endIds = [];

    var batchIds = batchedIndices[i].batchIds;
    var batchIdsLength = batchIds.length;

    for (var j = 0; j < batchIdsLength; ++j) {
      var id = batchIds[j];
      if (id === batchId) {
        continue;
      }

      var offsetIndex = batchIdLookUp[id];
      if (indexOffsets[offsetIndex] < offset) {
        startIds.push(id);
      } else {
        endIds.push(id);
      }
    }

    if (endIds.length !== 0) {
      batchedIndices.push(
        new Vector3DTileBatch({
          color: Color.clone(batchedIndices[i].color),
          offset: offset + count,
          count:
            batchedIndices[i].offset + batchedIndices[i].count - (offset + count),
          batchIds: endIds,
        })
      );
    }

    if (startIds.length !== 0) {
      batchedIndices[i].count = offset - batchedIndices[i].offset;
      batchedIndices[i].batchIds = startIds;
    } else {
      batchedIndices.splice(i, 1);
    }

    this._batchDirty = true;
  };

  function queueCommands(primitive, frameState, commands, commandsIgnoreShow) {
    var classificationType = primitive.classificationType;
    var queueTerrainCommands =
      classificationType !== ClassificationType$1.CESIUM_3D_TILE;
    var queue3DTilesCommands = classificationType !== ClassificationType$1.TERRAIN;

    var commandList = frameState.commandList;
    var commandLength = commands.length;
    var command;
    var i;
    for (i = 0; i < commandLength; ++i) {
      if (queueTerrainCommands) {
        command = commands[i];
        command.pass = Pass$1.TERRAIN_CLASSIFICATION;
        commandList.push(command);
      }
      if (queue3DTilesCommands) {
        command = commands[i].derivedCommands.tileset;
        command.pass = Pass$1.CESIUM_3D_TILE_CLASSIFICATION;
        commandList.push(command);
      }
    }

    if (!frameState.invertClassification || !defined(commandsIgnoreShow)) {
      return;
    }

    commandLength = commandsIgnoreShow.length;
    for (i = 0; i < commandLength; ++i) {
      commandList.push(commandsIgnoreShow[i]);
    }
  }

  function queueWireframeCommands(frameState, commands) {
    var commandList = frameState.commandList;
    var commandLength = commands.length;
    for (var i = 0; i < commandLength; i += 2) {
      var command = commands[i + 1];
      command.pass = Pass$1.OPAQUE;
      commandList.push(command);
    }
  }

  function updateWireframe(primitive) {
    var earlyExit = primitive.debugWireframe === primitive._debugWireframe;
    earlyExit =
      earlyExit && !(primitive.debugWireframe && primitive._wireframeDirty);
    if (earlyExit) {
      return;
    }

    if (!defined(primitive._rsWireframe)) {
      primitive._rsWireframe = RenderState.fromCache({});
    }

    var rs;
    var type;

    if (primitive.debugWireframe) {
      rs = primitive._rsWireframe;
      type = PrimitiveType$1.LINES;
    } else {
      rs = primitive._rsColorPass;
      type = PrimitiveType$1.TRIANGLES;
    }

    var commands = primitive._commands;
    var commandLength = commands.length;
    for (var i = 0; i < commandLength; i += 2) {
      var command = commands[i + 1];
      command.renderState = rs;
      command.primitiveType = type;
    }

    primitive._debugWireframe = primitive.debugWireframe;
    primitive._wireframeDirty = false;
  }

  /**
   * Updates the batches and queues the commands for rendering.
   *
   * @param {FrameState} frameState The current frame state.
   */
  Vector3DTilePrimitive.prototype.update = function (frameState) {
    var context = frameState.context;

    createVertexArray$1(this, context);
    createShaders(this, context);
    createRenderStates$2(this);
    createUniformMap(this, context);

    var passes = frameState.passes;
    if (passes.render) {
      createColorCommands$1(this, context);
      createColorCommandsIgnoreShow(this, frameState);
      updateWireframe(this);

      if (this._debugWireframe) {
        queueWireframeCommands(frameState, this._commands);
      } else {
        queueCommands(this, frameState, this._commands, this._commandsIgnoreShow);
      }
    }

    if (passes.pick) {
      createPickCommands$1(this);
      queueCommands(this, frameState, this._pickCommands);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  Vector3DTilePrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  Vector3DTilePrimitive.prototype.destroy = function () {
    this._va = this._va && this._va.destroy();
    this._sp = this._sp && this._sp.destroy();
    this._spPick = this._spPick && this._spPick.destroy();
    this._vaSwap = this._vaSwap && this._vaSwap.destroy();
    return destroyObject(this);
  };

  var boundingSphereCartesian3Scratch = new Cartesian3();

  var ModelState = ModelUtility.ModelState;

  ///////////////////////////////////////////////////////////////////////////

  /**
   * A 3D model for classifying other 3D assets based on glTF, the runtime 3D asset format.
   * This is a special case when a model of a 3D tileset becomes a classifier when setting {@link Cesium3DTileset#classificationType}.
   *
   * @alias ClassificationModel
   * @constructor
   *
   * @private
   *
   * @param {Object} options Object with the following properties:
   * @param {ArrayBuffer|Uint8Array} options.gltf A binary glTF buffer.
   * @param {Boolean} [options.show=true] Determines if the model primitive will be shown.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the model from model to world coordinates.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Draws the bounding sphere for each draw command in the model.
   * @param {Boolean} [options.debugWireframe=false] For debugging only. Draws the model in wireframe.
   * @param {ClassificationType} [options.classificationType] What this model will classify.
   *
   * @exception {RuntimeError} Only binary glTF is supported.
   * @exception {RuntimeError} Buffer data must be embedded in the binary glTF.
   * @exception {RuntimeError} Only one node is supported for classification and it must have a mesh.
   * @exception {RuntimeError} Only one mesh is supported when using b3dm for classification.
   * @exception {RuntimeError} Only one primitive per mesh is supported when using b3dm for classification.
   * @exception {RuntimeError} The mesh must have a position attribute.
   * @exception {RuntimeError} The mesh must have a batch id attribute.
   */
  function ClassificationModel(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var gltf = options.gltf;
    if (gltf instanceof ArrayBuffer) {
      gltf = new Uint8Array(gltf);
    }

    if (gltf instanceof Uint8Array) {
      // Parse and update binary glTF
      gltf = parseGlb(gltf);
      updateVersion(gltf);
      addDefaults(gltf);
      processModelMaterialsCommon(gltf);
      processPbrMaterials(gltf);
    } else {
      throw new RuntimeError("Only binary glTF is supported as a classifier.");
    }

    ForEach.buffer(gltf, function (buffer) {
      if (!defined(buffer.extras._pipeline.source)) {
        throw new RuntimeError(
          "Buffer data must be embedded in the binary gltf."
        );
      }
    });

    var gltfNodes = gltf.nodes;
    var gltfMeshes = gltf.meshes;

    var gltfNode = gltfNodes[0];
    var meshId = gltfNode.mesh;
    if (gltfNodes.length !== 1 || !defined(meshId)) {
      throw new RuntimeError(
        "Only one node is supported for classification and it must have a mesh."
      );
    }

    if (gltfMeshes.length !== 1) {
      throw new RuntimeError(
        "Only one mesh is supported when using b3dm for classification."
      );
    }

    var gltfPrimitives = gltfMeshes[0].primitives;
    if (gltfPrimitives.length !== 1) {
      throw new RuntimeError(
        "Only one primitive per mesh is supported when using b3dm for classification."
      );
    }

    var gltfPositionAttribute = gltfPrimitives[0].attributes.POSITION;
    if (!defined(gltfPositionAttribute)) {
      throw new RuntimeError("The mesh must have a position attribute.");
    }

    var gltfBatchIdAttribute = gltfPrimitives[0].attributes._BATCHID;
    if (!defined(gltfBatchIdAttribute)) {
      throw new RuntimeError("The mesh must have a batch id attribute.");
    }

    this._gltf = gltf;

    /**
     * Determines if the model primitive will be shown.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * The 4x4 transformation matrix that transforms the model from model to world coordinates.
     * When this is the identity matrix, the model is drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type {Matrix4}
     *
     * @default {@link Matrix4.IDENTITY}
     *
     * @example
     * var origin = Cesium.Cartesian3.fromDegrees(-95.0, 40.0, 200000.0);
     * m.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = Matrix4.clone(this.modelMatrix);

    this._ready = false;
    this._readyPromise = when.defer();

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the model.  A glTF primitive corresponds
     * to one draw command.  A glTF mesh has an array of primitives, often of length one.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );
    this._debugShowBoundingVolume = false;

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the model in wireframe.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugWireframe = defaultValue(options.debugWireframe, false);
    this._debugWireframe = false;

    this._classificationType = options.classificationType;

    // Undocumented options
    this._vertexShaderLoaded = options.vertexShaderLoaded;
    this._classificationShaderLoaded = options.classificationShaderLoaded;
    this._uniformMapLoaded = options.uniformMapLoaded;
    this._pickIdLoaded = options.pickIdLoaded;
    this._ignoreCommands = defaultValue(options.ignoreCommands, false);
    this._upAxis = defaultValue(options.upAxis, Axis$1.Y);
    this._batchTable = options.batchTable;

    this._computedModelMatrix = new Matrix4(); // Derived from modelMatrix and axis
    this._initialRadius = undefined; // Radius without model's scale property, model-matrix scale, animations, or skins
    this._boundingSphere = undefined;
    this._scaledBoundingSphere = new BoundingSphere();
    this._state = ModelState.NEEDS_LOAD;
    this._loadResources = undefined;

    this._mode = undefined;
    this._dirty = false; // true when the model was transformed this frame

    this._nodeMatrix = new Matrix4();
    this._primitive = undefined;

    this._extensionsUsed = undefined; // Cached used glTF extensions
    this._extensionsRequired = undefined; // Cached required glTF extensions
    this._quantizedUniforms = undefined; // Quantized uniforms for WEB3D_quantized_attributes

    this._buffers = {};
    this._vertexArray = undefined;
    this._shaderProgram = undefined;
    this._uniformMap = undefined;

    this._geometryByteLength = 0;
    this._trianglesLength = 0;

    // CESIUM_RTC extension
    this._rtcCenter = undefined; // reference to either 3D or 2D
    this._rtcCenterEye = undefined; // in eye coordinates
    this._rtcCenter3D = undefined; // in world coordinates
    this._rtcCenter2D = undefined; // in projected world coordinates
  }

  Object.defineProperties(ClassificationModel.prototype, {
    /**
     * The object for the glTF JSON, including properties with default values omitted
     * from the JSON provided to this model.
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @default undefined
     */
    gltf: {
      get: function () {
        return this._gltf;
      },
    },

    /**
     * The model's bounding sphere in its local coordinate system.
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     *
     * @default undefined
     *
     * @exception {DeveloperError} The model is not loaded.  Use ClassificationModel.readyPromise or wait for ClassificationModel.ready to be true.
     *
     * @example
     * // Center in WGS84 coordinates
     * var center = Cesium.Matrix4.multiplyByPoint(model.modelMatrix, model.boundingSphere.center, new Cesium.Cartesian3());
     */
    boundingSphere: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (this._state !== ModelState.LOADED) {
          throw new DeveloperError(
            "The model is not loaded.  Use ClassificationModel.readyPromise or wait for ClassificationModel.ready to be true."
          );
        }
        //>>includeEnd('debug');

        var modelMatrix = this.modelMatrix;
        var nonUniformScale = Matrix4.getScale(
          modelMatrix,
          boundingSphereCartesian3Scratch
        );

        var scaledBoundingSphere = this._scaledBoundingSphere;
        scaledBoundingSphere.center = Cartesian3.multiplyComponents(
          this._boundingSphere.center,
          nonUniformScale,
          scaledBoundingSphere.center
        );
        scaledBoundingSphere.radius =
          Cartesian3.maximumComponent(nonUniformScale) * this._initialRadius;

        if (defined(this._rtcCenter)) {
          Cartesian3.add(
            this._rtcCenter,
            scaledBoundingSphere.center,
            scaledBoundingSphere.center
          );
        }

        return scaledBoundingSphere;
      },
    },

    /**
     * When <code>true</code>, this model is ready to render, i.e., the external binary, image,
     * and shader files were downloaded and the WebGL resources were created.  This is set to
     * <code>true</code> right before {@link ClassificationModel#readyPromise} is resolved.
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets the promise that will be resolved when this model is ready to render, i.e., when the external binary, image,
     * and shader files were downloaded and the WebGL resources were created.
     * <p>
     * This promise is resolved at the end of the frame before the first frame the model is rendered in.
     * </p>
     *
     * @memberof ClassificationModel.prototype
     * @type {Promise.<ClassificationModel>}
     * @readonly
     *
     * @see ClassificationModel#ready
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Returns true if the model was transformed this frame
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    dirty: {
      get: function () {
        return this._dirty;
      },
    },

    /**
     * Returns an object with all of the glTF extensions used.
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {Object}
     * @readonly
     */
    extensionsUsed: {
      get: function () {
        if (!defined(this._extensionsUsed)) {
          this._extensionsUsed = ModelUtility.getUsedExtensions(this.gltf);
        }
        return this._extensionsUsed;
      },
    },

    /**
     * Returns an object with all of the glTF extensions required.
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {Object}
     * @readonly
     */
    extensionsRequired: {
      get: function () {
        if (!defined(this._extensionsRequired)) {
          this._extensionsRequired = ModelUtility.getRequiredExtensions(
            this.gltf
          );
        }
        return this._extensionsRequired;
      },
    },

    /**
     * Gets the model's up-axis.
     * By default models are y-up according to the glTF spec, however geo-referenced models will typically be z-up.
     *
     * @memberof ClassificationModel.prototype
     *
     * @type {Number}
     * @default Axis.Y
     * @readonly
     *
     * @private
     */
    upAxis: {
      get: function () {
        return this._upAxis;
      },
    },

    /**
     * Gets the model's triangle count.
     *
     * @private
     */
    trianglesLength: {
      get: function () {
        return this._trianglesLength;
      },
    },

    /**
     * Gets the model's geometry memory in bytes. This includes all vertex and index buffers.
     *
     * @private
     */
    geometryByteLength: {
      get: function () {
        return this._geometryByteLength;
      },
    },

    /**
     * Gets the model's texture memory in bytes.
     *
     * @private
     */
    texturesByteLength: {
      get: function () {
        return 0;
      },
    },

    /**
     * Gets the model's classification type.
     * @memberof ClassificationModel.prototype
     * @type {ClassificationType}
     */
    classificationType: {
      get: function () {
        return this._classificationType;
      },
    },
  });

  ///////////////////////////////////////////////////////////////////////////

  function addBuffersToLoadResources(model) {
    var gltf = model.gltf;
    var loadResources = model._loadResources;
    ForEach.buffer(gltf, function (buffer, id) {
      loadResources.buffers[id] = buffer.extras._pipeline.source;
    });
  }

  function parseBufferViews(model) {
    var bufferViews = model.gltf.bufferViews;

    var vertexBuffersToCreate = model._loadResources.vertexBuffersToCreate;

    // Only ARRAY_BUFFER here.  ELEMENT_ARRAY_BUFFER created below.
    ForEach.bufferView(model.gltf, function (bufferView, id) {
      if (bufferView.target === WebGLConstants$1.ARRAY_BUFFER) {
        vertexBuffersToCreate.enqueue(id);
      }
    });

    var indexBuffersToCreate = model._loadResources.indexBuffersToCreate;
    var indexBufferIds = {};

    // The Cesium Renderer requires knowing the datatype for an index buffer
    // at creation type, which is not part of the glTF bufferview so loop
    // through glTF accessors to create the bufferview's index buffer.
    ForEach.accessor(model.gltf, function (accessor) {
      var bufferViewId = accessor.bufferView;
      var bufferView = bufferViews[bufferViewId];

      if (
        bufferView.target === WebGLConstants$1.ELEMENT_ARRAY_BUFFER &&
        !defined(indexBufferIds[bufferViewId])
      ) {
        indexBufferIds[bufferViewId] = true;
        indexBuffersToCreate.enqueue({
          id: bufferViewId,
          componentType: accessor.componentType,
        });
      }
    });
  }

  function createVertexBuffer(bufferViewId, model) {
    var loadResources = model._loadResources;
    var bufferViews = model.gltf.bufferViews;
    var bufferView = bufferViews[bufferViewId];
    var vertexBuffer = loadResources.getBuffer(bufferView);
    model._buffers[bufferViewId] = vertexBuffer;
    model._geometryByteLength += vertexBuffer.byteLength;
  }

  function createIndexBuffer(bufferViewId, componentType, model) {
    var loadResources = model._loadResources;
    var bufferViews = model.gltf.bufferViews;
    var bufferView = bufferViews[bufferViewId];
    var indexBuffer = {
      typedArray: loadResources.getBuffer(bufferView),
      indexDatatype: componentType,
    };
    model._buffers[bufferViewId] = indexBuffer;
    model._geometryByteLength += indexBuffer.typedArray.byteLength;
  }

  function createBuffers(model) {
    var loadResources = model._loadResources;

    if (loadResources.pendingBufferLoads !== 0) {
      return;
    }

    var vertexBuffersToCreate = loadResources.vertexBuffersToCreate;
    var indexBuffersToCreate = loadResources.indexBuffersToCreate;

    while (vertexBuffersToCreate.length > 0) {
      createVertexBuffer(vertexBuffersToCreate.dequeue(), model);
    }

    while (indexBuffersToCreate.length > 0) {
      var i = indexBuffersToCreate.dequeue();
      createIndexBuffer(i.id, i.componentType, model);
    }
  }

  function modifyShaderForQuantizedAttributes(shader, model) {
    var primitive = model.gltf.meshes[0].primitives[0];
    var result = ModelUtility.modifyShaderForQuantizedAttributes(
      model.gltf,
      primitive,
      shader
    );
    model._quantizedUniforms = result.uniforms;
    return result.shader;
  }

  function modifyShader(shader, callback) {
    if (defined(callback)) {
      shader = callback(shader);
    }
    return shader;
  }

  function createProgram(model) {
    var gltf = model.gltf;

    var positionName = ModelUtility.getAttributeOrUniformBySemantic(
      gltf,
      "POSITION"
    );
    var batchIdName = ModelUtility.getAttributeOrUniformBySemantic(
      gltf,
      "_BATCHID"
    );

    var attributeLocations = {};
    attributeLocations[positionName] = 0;
    attributeLocations[batchIdName] = 1;

    var modelViewProjectionName = ModelUtility.getAttributeOrUniformBySemantic(
      gltf,
      "MODELVIEWPROJECTION"
    );

    var uniformDecl;
    var toClip;

    if (!defined(modelViewProjectionName)) {
      var projectionName = ModelUtility.getAttributeOrUniformBySemantic(
        gltf,
        "PROJECTION"
      );
      var modelViewName = ModelUtility.getAttributeOrUniformBySemantic(
        gltf,
        "MODELVIEW"
      );
      if (!defined(modelViewName)) {
        modelViewName = ModelUtility.getAttributeOrUniformBySemantic(
          gltf,
          "CESIUM_RTC_MODELVIEW"
        );
      }

      uniformDecl =
        "uniform mat4 " +
        modelViewName +
        ";\n" +
        "uniform mat4 " +
        projectionName +
        ";\n";
      toClip =
        projectionName +
        " * " +
        modelViewName +
        " * vec4(" +
        positionName +
        ", 1.0)";
    } else {
      uniformDecl = "uniform mat4 " + modelViewProjectionName + ";\n";
      toClip = modelViewProjectionName + " * vec4(" + positionName + ", 1.0)";
    }

    var computePosition = "    vec4 positionInClipCoords = " + toClip + ";\n";

    var vs =
      "attribute vec3 " +
      positionName +
      ";\n" +
      "attribute float " +
      batchIdName +
      ";\n" +
      uniformDecl +
      "void main() {\n" +
      computePosition +
      "    gl_Position = czm_depthClamp(positionInClipCoords);\n" +
      "}\n";
    var fs =
      "#ifdef GL_EXT_frag_depth\n" +
      "#extension GL_EXT_frag_depth : enable\n" +
      "#endif\n" +
      "void main() \n" +
      "{ \n" +
      "    gl_FragColor = vec4(1.0); \n" +
      "    czm_writeDepthClamp();\n" +
      "}\n";

    if (model.extensionsUsed.WEB3D_quantized_attributes) {
      vs = modifyShaderForQuantizedAttributes(vs, model);
    }

    var drawVS = modifyShader(vs, model._vertexShaderLoaded);
    var drawFS = modifyShader(fs, model._classificationShaderLoaded);

    model._shaderProgram = {
      vertexShaderSource: drawVS,
      fragmentShaderSource: drawFS,
      attributeLocations: attributeLocations,
    };
  }

  function getAttributeLocations() {
    return {
      POSITION: 0,
      _BATCHID: 1,
    };
  }

  function createVertexArray$2(model) {
    var loadResources = model._loadResources;
    if (!loadResources.finishedBuffersCreation() || defined(model._vertexArray)) {
      return;
    }

    var rendererBuffers = model._buffers;
    var gltf = model.gltf;
    var accessors = gltf.accessors;
    var meshes = gltf.meshes;
    var primitives = meshes[0].primitives;

    var primitive = primitives[0];
    var attributeLocations = getAttributeLocations();
    var attributes = {};
    ForEach.meshPrimitiveAttribute(primitive, function (
      accessorId,
      attributeName
    ) {
      // Skip if the attribute is not used by the material, e.g., because the asset
      // was exported with an attribute that wasn't used and the asset wasn't optimized.
      var attributeLocation = attributeLocations[attributeName];
      if (defined(attributeLocation)) {
        var a = accessors[accessorId];
        attributes[attributeName] = {
          index: attributeLocation,
          vertexBuffer: rendererBuffers[a.bufferView],
          componentsPerAttribute: numberOfComponentsForType(a.type),
          componentDatatype: a.componentType,
          offsetInBytes: a.byteOffset,
          strideInBytes: getAccessorByteStride(gltf, a),
        };
      }
    });

    var indexBuffer;
    if (defined(primitive.indices)) {
      var accessor = accessors[primitive.indices];
      indexBuffer = rendererBuffers[accessor.bufferView];
    }
    model._vertexArray = {
      attributes: attributes,
      indexBuffer: indexBuffer,
    };
  }

  var gltfSemanticUniforms$1 = {
    PROJECTION: function (uniformState, model) {
      return ModelUtility.getGltfSemanticUniforms().PROJECTION(
        uniformState,
        model
      );
    },
    MODELVIEW: function (uniformState, model) {
      return ModelUtility.getGltfSemanticUniforms().MODELVIEW(
        uniformState,
        model
      );
    },
    CESIUM_RTC_MODELVIEW: function (uniformState, model) {
      return ModelUtility.getGltfSemanticUniforms().CESIUM_RTC_MODELVIEW(
        uniformState,
        model
      );
    },
    MODELVIEWPROJECTION: function (uniformState, model) {
      return ModelUtility.getGltfSemanticUniforms().MODELVIEWPROJECTION(
        uniformState,
        model
      );
    },
  };

  function createUniformMap$1(model, context) {
    if (defined(model._uniformMap)) {
      return;
    }

    var uniformMap = {};
    ForEach.technique(model.gltf, function (technique) {
      ForEach.techniqueUniform(technique, function (uniform, uniformName) {
        if (
          !defined(uniform.semantic) ||
          !defined(gltfSemanticUniforms$1[uniform.semantic])
        ) {
          return;
        }

        uniformMap[uniformName] = gltfSemanticUniforms$1[uniform.semantic](
          context.uniformState,
          model
        );
      });
    });

    model._uniformMap = uniformMap;
  }

  function createUniformsForQuantizedAttributes(model, primitive) {
    return ModelUtility.createUniformsForQuantizedAttributes(
      model.gltf,
      primitive,
      model._quantizedUniforms
    );
  }

  function triangleCountFromPrimitiveIndices(primitive, indicesCount) {
    switch (primitive.mode) {
      case PrimitiveType$1.TRIANGLES:
        return indicesCount / 3;
      case PrimitiveType$1.TRIANGLE_STRIP:
      case PrimitiveType$1.TRIANGLE_FAN:
        return Math.max(indicesCount - 2, 0);
      default:
        return 0;
    }
  }

  function createPrimitive(model) {
    var batchTable = model._batchTable;

    var uniformMap = model._uniformMap;
    var vertexArray = model._vertexArray;

    var gltf = model.gltf;
    var accessors = gltf.accessors;
    var gltfMeshes = gltf.meshes;
    var primitive = gltfMeshes[0].primitives[0];
    var ix = accessors[primitive.indices];

    var positionAccessor = primitive.attributes.POSITION;
    var minMax = ModelUtility.getAccessorMinMax(gltf, positionAccessor);
    var boundingSphere = BoundingSphere.fromCornerPoints(
      Cartesian3.fromArray(minMax.min),
      Cartesian3.fromArray(minMax.max)
    );

    var offset;
    var count;
    if (defined(ix)) {
      count = ix.count;
      offset = ix.byteOffset / IndexDatatype$1.getSizeInBytes(ix.componentType); // glTF has offset in bytes.  Cesium has offsets in indices
    } else {
      var positions = accessors[primitive.attributes.POSITION];
      count = positions.count;
      offset = 0;
    }

    // Update model triangle count using number of indices
    model._trianglesLength += triangleCountFromPrimitiveIndices(primitive, count);

    // Allow callback to modify the uniformMap
    if (defined(model._uniformMapLoaded)) {
      uniformMap = model._uniformMapLoaded(uniformMap);
    }

    // Add uniforms for decoding quantized attributes if used
    if (model.extensionsUsed.WEB3D_quantized_attributes) {
      var quantizedUniformMap = createUniformsForQuantizedAttributes(
        model,
        primitive
      );
      uniformMap = combine(uniformMap, quantizedUniformMap);
    }

    var attribute = vertexArray.attributes.POSITION;
    var componentDatatype = attribute.componentDatatype;
    var typedArray = attribute.vertexBuffer;
    var byteOffset = typedArray.byteOffset;
    var bufferLength =
      typedArray.byteLength / ComponentDatatype$1.getSizeInBytes(componentDatatype);
    var positionsBuffer = ComponentDatatype$1.createArrayBufferView(
      componentDatatype,
      typedArray.buffer,
      byteOffset,
      bufferLength
    );

    attribute = vertexArray.attributes._BATCHID;
    componentDatatype = attribute.componentDatatype;
    typedArray = attribute.vertexBuffer;
    byteOffset = typedArray.byteOffset;
    bufferLength =
      typedArray.byteLength / ComponentDatatype$1.getSizeInBytes(componentDatatype);
    var vertexBatchIds = ComponentDatatype$1.createArrayBufferView(
      componentDatatype,
      typedArray.buffer,
      byteOffset,
      bufferLength
    );

    var buffer = vertexArray.indexBuffer.typedArray;
    var indices;
    if (vertexArray.indexBuffer.indexDatatype === IndexDatatype$1.UNSIGNED_SHORT) {
      indices = new Uint16Array(
        buffer.buffer,
        buffer.byteOffset,
        buffer.byteLength / Uint16Array.BYTES_PER_ELEMENT
      );
    } else {
      indices = new Uint32Array(
        buffer.buffer,
        buffer.byteOffset,
        buffer.byteLength / Uint32Array.BYTES_PER_ELEMENT
      );
    }

    positionsBuffer = arraySlice(positionsBuffer);
    vertexBatchIds = arraySlice(vertexBatchIds);
    indices = arraySlice(indices, offset, offset + count);

    var batchIds = [];
    var indexCounts = [];
    var indexOffsets = [];
    var batchedIndices = [];

    var currentId = vertexBatchIds[indices[0]];
    batchIds.push(currentId);
    indexOffsets.push(0);

    var batchId;
    var indexOffset;
    var indexCount;
    var indicesLength = indices.length;
    for (var j = 1; j < indicesLength; ++j) {
      batchId = vertexBatchIds[indices[j]];
      if (batchId !== currentId) {
        indexOffset = indexOffsets[indexOffsets.length - 1];
        indexCount = j - indexOffset;

        batchIds.push(batchId);
        indexCounts.push(indexCount);
        indexOffsets.push(j);

        batchedIndices.push(
          new Vector3DTileBatch({
            offset: indexOffset,
            count: indexCount,
            batchIds: [currentId],
            color: Color.WHITE,
          })
        );

        currentId = batchId;
      }
    }

    indexOffset = indexOffsets[indexOffsets.length - 1];
    indexCount = indicesLength - indexOffset;

    indexCounts.push(indexCount);
    batchedIndices.push(
      new Vector3DTileBatch({
        offset: indexOffset,
        count: indexCount,
        batchIds: [currentId],
        color: Color.WHITE,
      })
    );

    var shader = model._shaderProgram;
    var vertexShaderSource = shader.vertexShaderSource;
    var fragmentShaderSource = shader.fragmentShaderSource;
    var attributeLocations = shader.attributeLocations;
    var pickId = defined(model._pickIdLoaded) ? model._pickIdLoaded() : undefined;

    model._primitive = new Vector3DTilePrimitive({
      classificationType: model._classificationType,
      positions: positionsBuffer,
      indices: indices,
      indexOffsets: indexOffsets,
      indexCounts: indexCounts,
      batchIds: batchIds,
      vertexBatchIds: vertexBatchIds,
      batchedIndices: batchedIndices,
      batchTable: batchTable,
      boundingVolume: new BoundingSphere(), // updated in update()
      _vertexShaderSource: vertexShaderSource,
      _fragmentShaderSource: fragmentShaderSource,
      _attributeLocations: attributeLocations,
      _uniformMap: uniformMap,
      _pickId: pickId,
      _modelMatrix: new Matrix4(), // updated in update()
      _boundingSphere: boundingSphere, // used to update boundingVolume
    });

    // Release CPU resources
    model._buffers = undefined;
    model._vertexArray = undefined;
    model._shaderProgram = undefined;
    model._uniformMap = undefined;
  }

  function createRuntimeNodes(model) {
    var loadResources = model._loadResources;
    if (!loadResources.finished()) {
      return;
    }

    if (defined(model._primitive)) {
      return;
    }

    var gltf = model.gltf;
    var nodes = gltf.nodes;
    var gltfNode = nodes[0];
    model._nodeMatrix = ModelUtility.getTransform(gltfNode, model._nodeMatrix);

    createPrimitive(model);
  }

  function createResources(model, frameState) {
    var context = frameState.context;

    ModelUtility.checkSupportedGlExtensions(model.gltf.glExtensionsUsed, context);
    createBuffers(model); // using glTF bufferViews
    createProgram(model);
    createVertexArray$2(model); // using glTF meshes
    createUniformMap$1(model, context); // using glTF materials/techniques
    createRuntimeNodes(model); // using glTF scene
  }

  ///////////////////////////////////////////////////////////////////////////

  var scratchComputedTranslation = new Cartesian4();
  var scratchComputedMatrixIn2D = new Matrix4();

  function updateNodeModelMatrix(
    model,
    modelTransformChanged,
    justLoaded,
    projection
  ) {
    var computedModelMatrix = model._computedModelMatrix;

    if (model._mode !== SceneMode$1.SCENE3D && !model._ignoreCommands) {
      var translation = Matrix4.getColumn(
        computedModelMatrix,
        3,
        scratchComputedTranslation
      );
      if (!Cartesian4.equals(translation, Cartesian4.UNIT_W)) {
        computedModelMatrix = Transforms.basisTo2D(
          projection,
          computedModelMatrix,
          scratchComputedMatrixIn2D
        );
        model._rtcCenter = model._rtcCenter3D;
      } else {
        var center = model.boundingSphere.center;
        var to2D = Transforms.wgs84To2DModelMatrix(
          projection,
          center,
          scratchComputedMatrixIn2D
        );
        computedModelMatrix = Matrix4.multiply(
          to2D,
          computedModelMatrix,
          scratchComputedMatrixIn2D
        );

        if (defined(model._rtcCenter)) {
          Matrix4.setTranslation(
            computedModelMatrix,
            Cartesian4.UNIT_W,
            computedModelMatrix
          );
          model._rtcCenter = model._rtcCenter2D;
        }
      }
    }

    var primitive = model._primitive;

    if (modelTransformChanged || justLoaded) {
      Matrix4.multiplyTransformation(
        computedModelMatrix,
        model._nodeMatrix,
        primitive._modelMatrix
      );
      BoundingSphere.transform(
        primitive._boundingSphere,
        primitive._modelMatrix,
        primitive._boundingVolume
      );

      if (defined(model._rtcCenter)) {
        Cartesian3.add(
          model._rtcCenter,
          primitive._boundingVolume.center,
          primitive._boundingVolume.center
        );
      }
    }
  }

  ///////////////////////////////////////////////////////////////////////////

  ClassificationModel.prototype.updateCommands = function (batchId, color) {
    this._primitive.updateCommands(batchId, color);
  };

  ClassificationModel.prototype.update = function (frameState) {
    if (frameState.mode === SceneMode$1.MORPHING) {
      return;
    }

    if (!FeatureDetection.supportsWebP.initialized) {
      FeatureDetection.supportsWebP.initialize();
      return;
    }
    var supportsWebP = FeatureDetection.supportsWebP();

    if (this._state === ModelState.NEEDS_LOAD && defined(this.gltf)) {
      this._state = ModelState.LOADING;
      if (this._state !== ModelState.FAILED) {
        var extensions = this.gltf.extensions;
        if (defined(extensions) && defined(extensions.CESIUM_RTC)) {
          var center = Cartesian3.fromArray(extensions.CESIUM_RTC.center);
          if (!Cartesian3.equals(center, Cartesian3.ZERO)) {
            this._rtcCenter3D = center;

            var projection = frameState.mapProjection;
            var ellipsoid = projection.ellipsoid;
            var cartographic = ellipsoid.cartesianToCartographic(
              this._rtcCenter3D
            );
            var projectedCart = projection.project(cartographic);
            Cartesian3.fromElements(
              projectedCart.z,
              projectedCart.x,
              projectedCart.y,
              projectedCart
            );
            this._rtcCenter2D = projectedCart;

            this._rtcCenterEye = new Cartesian3();
            this._rtcCenter = this._rtcCenter3D;
          }
        }

        this._loadResources = new ModelLoadResources();
        ModelUtility.parseBuffers(this);
      }
    }

    var loadResources = this._loadResources;
    var justLoaded = false;

    if (this._state === ModelState.LOADING) {
      // Transition from LOADING -> LOADED once resources are downloaded and created.
      // Textures may continue to stream in while in the LOADED state.
      if (loadResources.pendingBufferLoads === 0) {
        ModelUtility.checkSupportedExtensions(
          this.extensionsRequired,
          supportsWebP
        );

        addBuffersToLoadResources(this);
        parseBufferViews(this);

        this._boundingSphere = ModelUtility.computeBoundingSphere(this);
        this._initialRadius = this._boundingSphere.radius;
        createResources(this, frameState);
      }
      if (loadResources.finished()) {
        this._state = ModelState.LOADED;
        justLoaded = true;
      }
    }

    if (defined(loadResources) && this._state === ModelState.LOADED) {
      if (!justLoaded) {
        createResources(this, frameState);
      }

      if (loadResources.finished()) {
        this._loadResources = undefined; // Clear CPU memory since WebGL resources were created.
      }
    }

    var show = this.show;

    if ((show && this._state === ModelState.LOADED) || justLoaded) {
      this._dirty = false;
      var modelMatrix = this.modelMatrix;

      var modeChanged = frameState.mode !== this._mode;
      this._mode = frameState.mode;

      // ClassificationModel's model matrix needs to be updated
      var modelTransformChanged =
        !Matrix4.equals(this._modelMatrix, modelMatrix) || modeChanged;

      if (modelTransformChanged || justLoaded) {
        Matrix4.clone(modelMatrix, this._modelMatrix);

        var computedModelMatrix = this._computedModelMatrix;
        Matrix4.clone(modelMatrix, computedModelMatrix);
        if (this._upAxis === Axis$1.Y) {
          Matrix4.multiplyTransformation(
            computedModelMatrix,
            Axis$1.Y_UP_TO_Z_UP,
            computedModelMatrix
          );
        } else if (this._upAxis === Axis$1.X) {
          Matrix4.multiplyTransformation(
            computedModelMatrix,
            Axis$1.X_UP_TO_Z_UP,
            computedModelMatrix
          );
        }
      }

      // Update modelMatrix throughout the graph as needed
      if (modelTransformChanged || justLoaded) {
        updateNodeModelMatrix(
          this,
          modelTransformChanged,
          justLoaded,
          frameState.mapProjection
        );
        this._dirty = true;
      }
    }

    if (justLoaded) {
      // Called after modelMatrix update.
      var model = this;
      frameState.afterRender.push(function () {
        model._ready = true;
        model._readyPromise.resolve(model);
      });
      return;
    }

    if (show && !this._ignoreCommands) {
      this._primitive.debugShowBoundingVolume = this.debugShowBoundingVolume;
      this._primitive.debugWireframe = this.debugWireframe;
      this._primitive.update(frameState);
    }
  };

  ClassificationModel.prototype.isDestroyed = function () {
    return false;
  };

  ClassificationModel.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    return destroyObject(this);
  };

  /**
   * A Plane in Hessian Normal form to be used with {@link ClippingPlaneCollection}.
   * Compatible with mathematics functions in {@link Plane}
   *
   * @alias ClippingPlane
   * @constructor
   *
   * @param {Cartesian3} normal The plane's normal (normalized).
   * @param {Number} distance The shortest distance from the origin to the plane.  The sign of
   * <code>distance</code> determines which side of the plane the origin
   * is on.  If <code>distance</code> is positive, the origin is in the half-space
   * in the direction of the normal; if negative, the origin is in the half-space
   * opposite to the normal; if zero, the plane passes through the origin.
   */
  function ClippingPlane(normal, distance) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("normal", normal);
    Check.typeOf.number("distance", distance);
    //>>includeEnd('debug');

    this._distance = distance;
    this._normal = new UpdateChangedCartesian3(normal, this);
    this.onChangeCallback = undefined;
    this.index = -1; // to be set by ClippingPlaneCollection
  }

  Object.defineProperties(ClippingPlane.prototype, {
    /**
     * The shortest distance from the origin to the plane.  The sign of
     * <code>distance</code> determines which side of the plane the origin
     * is on.  If <code>distance</code> is positive, the origin is in the half-space
     * in the direction of the normal; if negative, the origin is in the half-space
     * opposite to the normal; if zero, the plane passes through the origin.
     *
     * @type {Number}
     * @memberof ClippingPlane.prototype
     */
    distance: {
      get: function () {
        return this._distance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number("value", value);
        //>>includeEnd('debug');
        if (defined(this.onChangeCallback) && value !== this._distance) {
          this.onChangeCallback(this.index);
        }
        this._distance = value;
      },
    },
    /**
     * The plane's normal.
     *
     * @type {Cartesian3}
     * @memberof ClippingPlane.prototype
     */
    normal: {
      get: function () {
        return this._normal;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.object("value", value);
        //>>includeEnd('debug');
        if (
          defined(this.onChangeCallback) &&
          !Cartesian3.equals(this._normal._cartesian3, value)
        ) {
          this.onChangeCallback(this.index);
        }
        // Set without firing callback again
        Cartesian3.clone(value, this._normal._cartesian3);
      },
    },
  });

  /**
   * Create a ClippingPlane from a Plane object.
   *
   * @param {Plane} plane The plane containing parameters to copy
   * @param {ClippingPlane} [result] The object on which to store the result
   * @returns {ClippingPlane} The ClippingPlane generated from the plane's parameters.
   */
  ClippingPlane.fromPlane = function (plane, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("plane", plane);
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new ClippingPlane(plane.normal, plane.distance);
    } else {
      result.normal = plane.normal;
      result.distance = plane.distance;
    }
    return result;
  };

  /**
   * Clones the ClippingPlane without setting its ownership.
   * @param {ClippingPlane} clippingPlane The ClippingPlane to be cloned
   * @param {ClippingPlane} [result] The object on which to store the cloned parameters.
   * @returns {ClippingPlane} a clone of the input ClippingPlane
   */
  ClippingPlane.clone = function (clippingPlane, result) {
    if (!defined(result)) {
      return new ClippingPlane(clippingPlane.normal, clippingPlane.distance);
    }
    result.normal = clippingPlane.normal;
    result.distance = clippingPlane.distance;
    return result;
  };

  /**
   * Wrapper on Cartesian3 that allows detection of Plane changes from "members of members," for example:
   *
   * var clippingPlane = new ClippingPlane(...);
   * clippingPlane.normal.z = -1.0;
   *
   * @private
   */
  function UpdateChangedCartesian3(normal, clippingPlane) {
    this._clippingPlane = clippingPlane;
    this._cartesian3 = Cartesian3.clone(normal);
  }

  Object.defineProperties(UpdateChangedCartesian3.prototype, {
    x: {
      get: function () {
        return this._cartesian3.x;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number("value", value);
        //>>includeEnd('debug');
        if (
          defined(this._clippingPlane.onChangeCallback) &&
          value !== this._cartesian3.x
        ) {
          this._clippingPlane.onChangeCallback(this._clippingPlane.index);
        }
        this._cartesian3.x = value;
      },
    },
    y: {
      get: function () {
        return this._cartesian3.y;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number("value", value);
        //>>includeEnd('debug');
        if (
          defined(this._clippingPlane.onChangeCallback) &&
          value !== this._cartesian3.y
        ) {
          this._clippingPlane.onChangeCallback(this._clippingPlane.index);
        }
        this._cartesian3.y = value;
      },
    },
    z: {
      get: function () {
        return this._cartesian3.z;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number("value", value);
        //>>includeEnd('debug');
        if (
          defined(this._clippingPlane.onChangeCallback) &&
          value !== this._cartesian3.z
        ) {
          this._clippingPlane.onChangeCallback(this._clippingPlane.index);
        }
        this._cartesian3.z = value;
      },
    },
  });

  /**
   * Specifies a set of clipping planes. Clipping planes selectively disable rendering in a region on the
   * outside of the specified list of {@link ClippingPlane} objects for a single gltf model, 3D Tileset, or the globe.
   * <p>
   * In general the clipping planes' coordinates are relative to the object they're attached to, so a plane with distance set to 0 will clip
   * through the center of the object.
   * </p>
   * <p>
   * For 3D Tiles, the root tile's transform is used to position the clipping planes. If a transform is not defined, the root tile's {@link Cesium3DTile#boundingSphere} is used instead.
   * </p>
   *
   * @alias ClippingPlaneCollection
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {ClippingPlane[]} [options.planes=[]] An array of {@link ClippingPlane} objects used to selectively disable rendering on the outside of each plane.
   * @param {Boolean} [options.enabled=true] Determines whether the clipping planes are active.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix specifying an additional transform relative to the clipping planes original coordinate system.
   * @param {Boolean} [options.unionClippingRegions=false] If true, a region will be clipped if it is on the outside of any plane in the collection. Otherwise, a region will only be clipped if it is on the outside of every plane.
   * @param {Color} [options.edgeColor=Color.WHITE] The color applied to highlight the edge along which an object is clipped.
   * @param {Number} [options.edgeWidth=0.0] The width, in pixels, of the highlight applied to the edge along which an object is clipped.
   *
   * @demo {@link https://sandcastle.cesium.com/?src=3D%20Tiles%20Clipping%20Planes.html|Clipping 3D Tiles and glTF models.}
   * @demo {@link https://sandcastle.cesium.com/?src=Terrain%20Clipping%20Planes.html|Clipping the Globe.}
   *
   * @example
   * // This clipping plane's distance is positive, which means its normal
   * // is facing the origin. This will clip everything that is behind
   * // the plane, which is anything with y coordinate < -5.
   * var clippingPlanes = new Cesium.ClippingPlaneCollection({
   *     planes : [
   *         new Cesium.ClippingPlane(new Cesium.Cartesian3(0.0, 1.0, 0.0), 5.0)
   *     ],
   * });
   * // Create an entity and attach the ClippingPlaneCollection to the model.
   * var entity = viewer.entities.add({
   *     position : Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706, 10000),
   *     model : {
   *         uri : 'model.gltf',
   *         minimumPixelSize : 128,
   *         maximumScale : 20000,
   *         clippingPlanes : clippingPlanes
   *     }
   * });
   * viewer.zoomTo(entity);
   */
  function ClippingPlaneCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._planes = [];

    // Do partial texture updates if just one plane is dirty.
    // If many planes are dirty, refresh the entire texture.
    this._dirtyIndex = -1;
    this._multipleDirtyPlanes = false;

    this._enabled = defaultValue(options.enabled, true);

    /**
     * The 4x4 transformation matrix specifying an additional transform relative to the clipping planes
     * original coordinate system.
     *
     * @type {Matrix4}
     * @default Matrix4.IDENTITY
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );

    /**
     * The color applied to highlight the edge along which an object is clipped.
     *
     * @type {Color}
     * @default Color.WHITE
     */
    this.edgeColor = Color.clone(defaultValue(options.edgeColor, Color.WHITE));

    /**
     * The width, in pixels, of the highlight applied to the edge along which an object is clipped.
     *
     * @type {Number}
     * @default 0.0
     */
    this.edgeWidth = defaultValue(options.edgeWidth, 0.0);

    /**
     * An event triggered when a new clipping plane is added to the collection.  Event handlers
     * are passed the new plane and the index at which it was added.
     * @type {Event}
     * @default Event()
     */
    this.planeAdded = new Event();

    /**
     * An event triggered when a new clipping plane is removed from the collection.  Event handlers
     * are passed the new plane and the index from which it was removed.
     * @type {Event}
     * @default Event()
     */
    this.planeRemoved = new Event();

    // If this ClippingPlaneCollection has an owner, only its owner should update or destroy it.
    // This is because in a Cesium3DTileset multiple models may reference the tileset's ClippingPlaneCollection.
    this._owner = undefined;

    var unionClippingRegions = defaultValue(options.unionClippingRegions, false);
    this._unionClippingRegions = unionClippingRegions;
    this._testIntersection = unionClippingRegions
      ? unionIntersectFunction
      : defaultIntersectFunction;

    this._uint8View = undefined;
    this._float32View = undefined;

    this._clippingPlanesTexture = undefined;

    // Add each ClippingPlane object.
    var planes = options.planes;
    if (defined(planes)) {
      var planesLength = planes.length;
      for (var i = 0; i < planesLength; ++i) {
        this.add(planes[i]);
      }
    }
  }

  function unionIntersectFunction(value) {
    return value === Intersect$1.OUTSIDE;
  }

  function defaultIntersectFunction(value) {
    return value === Intersect$1.INSIDE;
  }

  Object.defineProperties(ClippingPlaneCollection.prototype, {
    /**
     * Returns the number of planes in this collection.  This is commonly used with
     * {@link ClippingPlaneCollection#get} to iterate over all the planes
     * in the collection.
     *
     * @memberof ClippingPlaneCollection.prototype
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._planes.length;
      },
    },

    /**
     * If true, a region will be clipped if it is on the outside of any plane in the
     * collection. Otherwise, a region will only be clipped if it is on the
     * outside of every plane.
     *
     * @memberof ClippingPlaneCollection.prototype
     * @type {Boolean}
     * @default false
     */
    unionClippingRegions: {
      get: function () {
        return this._unionClippingRegions;
      },
      set: function (value) {
        if (this._unionClippingRegions === value) {
          return;
        }
        this._unionClippingRegions = value;
        this._testIntersection = value
          ? unionIntersectFunction
          : defaultIntersectFunction;
      },
    },

    /**
     * If true, clipping will be enabled.
     *
     * @memberof ClippingPlaneCollection.prototype
     * @type {Boolean}
     * @default true
     */
    enabled: {
      get: function () {
        return this._enabled;
      },
      set: function (value) {
        if (this._enabled === value) {
          return;
        }
        this._enabled = value;
      },
    },

    /**
     * Returns a texture containing packed, untransformed clipping planes.
     *
     * @memberof ClippingPlaneCollection.prototype
     * @type {Texture}
     * @readonly
     * @private
     */
    texture: {
      get: function () {
        return this._clippingPlanesTexture;
      },
    },

    /**
     * A reference to the ClippingPlaneCollection's owner, if any.
     *
     * @memberof ClippingPlaneCollection.prototype
     * @readonly
     * @private
     */
    owner: {
      get: function () {
        return this._owner;
      },
    },

    /**
     * Returns a Number encapsulating the state for this ClippingPlaneCollection.
     *
     * Clipping mode is encoded in the sign of the number, which is just the plane count.
     * Used for checking if shader regeneration is necessary.
     *
     * @memberof ClippingPlaneCollection.prototype
     * @returns {Number} A Number that describes the ClippingPlaneCollection's state.
     * @readonly
     * @private
     */
    clippingPlanesState: {
      get: function () {
        return this._unionClippingRegions
          ? this._planes.length
          : -this._planes.length;
      },
    },
  });

  function setIndexDirty(collection, index) {
    // If there's already a different _dirtyIndex set, more than one plane has changed since update.
    // Entire texture must be reloaded
    collection._multipleDirtyPlanes =
      collection._multipleDirtyPlanes ||
      (collection._dirtyIndex !== -1 && collection._dirtyIndex !== index);
    collection._dirtyIndex = index;
  }

  /**
   * Adds the specified {@link ClippingPlane} to the collection to be used to selectively disable rendering
   * on the outside of each plane. Use {@link ClippingPlaneCollection#unionClippingRegions} to modify
   * how modify the clipping behavior of multiple planes.
   *
   * @param {ClippingPlane} plane The ClippingPlane to add to the collection.
   *
   * @see ClippingPlaneCollection#unionClippingRegions
   * @see ClippingPlaneCollection#remove
   * @see ClippingPlaneCollection#removeAll
   */
  ClippingPlaneCollection.prototype.add = function (plane) {
    var newPlaneIndex = this._planes.length;

    var that = this;
    plane.onChangeCallback = function (index) {
      setIndexDirty(that, index);
    };
    plane.index = newPlaneIndex;

    setIndexDirty(this, newPlaneIndex);
    this._planes.push(plane);
    this.planeAdded.raiseEvent(plane, newPlaneIndex);
  };

  /**
   * Returns the plane in the collection at the specified index.  Indices are zero-based
   * and increase as planes are added.  Removing a plane shifts all planes after
   * it to the left, changing their indices.  This function is commonly used with
   * {@link ClippingPlaneCollection#length} to iterate over all the planes
   * in the collection.
   *
   * @param {Number} index The zero-based index of the plane.
   * @returns {ClippingPlane} The ClippingPlane at the specified index.
   *
   * @see ClippingPlaneCollection#length
   */
  ClippingPlaneCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("index", index);
    //>>includeEnd('debug');

    return this._planes[index];
  };

  function indexOf(planes, plane) {
    var length = planes.length;
    for (var i = 0; i < length; ++i) {
      if (Plane.equals(planes[i], plane)) {
        return i;
      }
    }

    return -1;
  }

  /**
   * Checks whether this collection contains a ClippingPlane equal to the given ClippingPlane.
   *
   * @param {ClippingPlane} [clippingPlane] The ClippingPlane to check for.
   * @returns {Boolean} true if this collection contains the ClippingPlane, false otherwise.
   *
   * @see ClippingPlaneCollection#get
   */
  ClippingPlaneCollection.prototype.contains = function (clippingPlane) {
    return indexOf(this._planes, clippingPlane) !== -1;
  };

  /**
   * Removes the first occurrence of the given ClippingPlane from the collection.
   *
   * @param {ClippingPlane} clippingPlane
   * @returns {Boolean} <code>true</code> if the plane was removed; <code>false</code> if the plane was not found in the collection.
   *
   * @see ClippingPlaneCollection#add
   * @see ClippingPlaneCollection#contains
   * @see ClippingPlaneCollection#removeAll
   */
  ClippingPlaneCollection.prototype.remove = function (clippingPlane) {
    var planes = this._planes;
    var index = indexOf(planes, clippingPlane);

    if (index === -1) {
      return false;
    }

    // Unlink this ClippingPlaneCollection from the ClippingPlane
    if (clippingPlane instanceof ClippingPlane) {
      clippingPlane.onChangeCallback = undefined;
      clippingPlane.index = -1;
    }

    // Shift and update indices
    var length = planes.length - 1;
    for (var i = index; i < length; ++i) {
      var planeToKeep = planes[i + 1];
      planes[i] = planeToKeep;
      if (planeToKeep instanceof ClippingPlane) {
        planeToKeep.index = i;
      }
    }

    // Indicate planes texture is dirty
    this._multipleDirtyPlanes = true;
    planes.length = length;

    this.planeRemoved.raiseEvent(clippingPlane, index);

    return true;
  };

  /**
   * Removes all planes from the collection.
   *
   * @see ClippingPlaneCollection#add
   * @see ClippingPlaneCollection#remove
   */
  ClippingPlaneCollection.prototype.removeAll = function () {
    // Dereference this ClippingPlaneCollection from all ClippingPlanes
    var planes = this._planes;
    var planesCount = planes.length;
    for (var i = 0; i < planesCount; ++i) {
      var plane = planes[i];
      if (plane instanceof ClippingPlane) {
        plane.onChangeCallback = undefined;
        plane.index = -1;
      }
      this.planeRemoved.raiseEvent(plane, i);
    }
    this._multipleDirtyPlanes = true;
    this._planes = [];
  };

  var distanceEncodeScratch = new Cartesian4();
  var oct32EncodeScratch = new Cartesian4();
  function packPlanesAsUint8(clippingPlaneCollection, startIndex, endIndex) {
    var uint8View = clippingPlaneCollection._uint8View;
    var planes = clippingPlaneCollection._planes;
    var byteIndex = 0;
    for (var i = startIndex; i < endIndex; ++i) {
      var plane = planes[i];

      var oct32Normal = AttributeCompression.octEncodeToCartesian4(
        plane.normal,
        oct32EncodeScratch
      );
      uint8View[byteIndex] = oct32Normal.x;
      uint8View[byteIndex + 1] = oct32Normal.y;
      uint8View[byteIndex + 2] = oct32Normal.z;
      uint8View[byteIndex + 3] = oct32Normal.w;

      var encodedDistance = Cartesian4.packFloat(
        plane.distance,
        distanceEncodeScratch
      );
      uint8View[byteIndex + 4] = encodedDistance.x;
      uint8View[byteIndex + 5] = encodedDistance.y;
      uint8View[byteIndex + 6] = encodedDistance.z;
      uint8View[byteIndex + 7] = encodedDistance.w;

      byteIndex += 8;
    }
  }

  // Pack starting at the beginning of the buffer to allow partial update
  function packPlanesAsFloats(clippingPlaneCollection, startIndex, endIndex) {
    var float32View = clippingPlaneCollection._float32View;
    var planes = clippingPlaneCollection._planes;

    var floatIndex = 0;
    for (var i = startIndex; i < endIndex; ++i) {
      var plane = planes[i];
      var normal = plane.normal;

      float32View[floatIndex] = normal.x;
      float32View[floatIndex + 1] = normal.y;
      float32View[floatIndex + 2] = normal.z;
      float32View[floatIndex + 3] = plane.distance;

      floatIndex += 4; // each plane is 4 floats
    }
  }

  function computeTextureResolution(pixelsNeeded, result) {
    var maxSize = ContextLimits.maximumTextureSize;
    result.x = Math.min(pixelsNeeded, maxSize);
    result.y = Math.ceil(pixelsNeeded / result.x);
    return result;
  }

  var textureResolutionScratch = new Cartesian2();
  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * build the resources for clipping planes.
   * <p>
   * Do not call this function directly.
   * </p>
   */
  ClippingPlaneCollection.prototype.update = function (frameState) {
    var clippingPlanesTexture = this._clippingPlanesTexture;
    var context = frameState.context;
    var useFloatTexture = ClippingPlaneCollection.useFloatTexture(context);

    // Compute texture requirements for current planes
    // In RGBA FLOAT, A plane is 4 floats packed to a RGBA.
    // In RGBA UNSIGNED_BYTE, A plane is a float in [0, 1) packed to RGBA and an Oct32 quantized normal,
    // so 8 bits or 2 pixels in RGBA.
    var pixelsNeeded = useFloatTexture ? this.length : this.length * 2;

    if (defined(clippingPlanesTexture)) {
      var currentPixelCount =
        clippingPlanesTexture.width * clippingPlanesTexture.height;
      // Recreate the texture to double current requirement if it isn't big enough or is 4 times larger than it needs to be.
      // Optimization note: this isn't exactly the classic resizeable array algorithm
      // * not necessarily checking for resize after each add/remove operation
      // * random-access deletes instead of just pops
      // * alloc ops likely more expensive than demonstrable via big-O analysis
      if (
        currentPixelCount < pixelsNeeded ||
        pixelsNeeded < 0.25 * currentPixelCount
      ) {
        clippingPlanesTexture.destroy();
        clippingPlanesTexture = undefined;
        this._clippingPlanesTexture = undefined;
      }
    }

    // If there are no clipping planes, there's nothing to update.
    if (this.length === 0) {
      return;
    }

    if (!defined(clippingPlanesTexture)) {
      var requiredResolution = computeTextureResolution(
        pixelsNeeded,
        textureResolutionScratch
      );
      // Allocate twice as much space as needed to avoid frequent texture reallocation.
      // Allocate in the Y direction, since texture may be as wide as context texture support.
      requiredResolution.y *= 2;

      if (useFloatTexture) {
        clippingPlanesTexture = new Texture({
          context: context,
          width: requiredResolution.x,
          height: requiredResolution.y,
          pixelFormat: PixelFormat$1.RGBA,
          pixelDatatype: PixelDatatype$1.FLOAT,
          sampler: Sampler.NEAREST,
          flipY: false,
        });
        this._float32View = new Float32Array(
          requiredResolution.x * requiredResolution.y * 4
        );
      } else {
        clippingPlanesTexture = new Texture({
          context: context,
          width: requiredResolution.x,
          height: requiredResolution.y,
          pixelFormat: PixelFormat$1.RGBA,
          pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
          sampler: Sampler.NEAREST,
          flipY: false,
        });
        this._uint8View = new Uint8Array(
          requiredResolution.x * requiredResolution.y * 4
        );
      }

      this._clippingPlanesTexture = clippingPlanesTexture;
      this._multipleDirtyPlanes = true;
    }

    var dirtyIndex = this._dirtyIndex;
    if (!this._multipleDirtyPlanes && dirtyIndex === -1) {
      return;
    }
    if (!this._multipleDirtyPlanes) {
      // partial updates possible
      var offsetX = 0;
      var offsetY = 0;
      if (useFloatTexture) {
        offsetY = Math.floor(dirtyIndex / clippingPlanesTexture.width);
        offsetX = Math.floor(dirtyIndex - offsetY * clippingPlanesTexture.width);

        packPlanesAsFloats(this, dirtyIndex, dirtyIndex + 1);
        clippingPlanesTexture.copyFrom(
          {
            width: 1,
            height: 1,
            arrayBufferView: this._float32View,
          },
          offsetX,
          offsetY
        );
      } else {
        offsetY = Math.floor((dirtyIndex * 2) / clippingPlanesTexture.width);
        offsetX = Math.floor(
          dirtyIndex * 2 - offsetY * clippingPlanesTexture.width
        );
        packPlanesAsUint8(this, dirtyIndex, dirtyIndex + 1);
        clippingPlanesTexture.copyFrom(
          {
            width: 2,
            height: 1,
            arrayBufferView: this._uint8View,
          },
          offsetX,
          offsetY
        );
      }
    } else if (useFloatTexture) {
      packPlanesAsFloats(this, 0, this._planes.length);
      clippingPlanesTexture.copyFrom({
        width: clippingPlanesTexture.width,
        height: clippingPlanesTexture.height,
        arrayBufferView: this._float32View,
      });
    } else {
      packPlanesAsUint8(this, 0, this._planes.length);
      clippingPlanesTexture.copyFrom({
        width: clippingPlanesTexture.width,
        height: clippingPlanesTexture.height,
        arrayBufferView: this._uint8View,
      });
    }

    this._multipleDirtyPlanes = false;
    this._dirtyIndex = -1;
  };

  var scratchMatrix = new Matrix4();
  var scratchPlane$2 = new Plane(Cartesian3.UNIT_X, 0.0);
  /**
   * Determines the type intersection with the planes of this ClippingPlaneCollection instance and the specified {@link TileBoundingVolume}.
   * @private
   *
   * @param {Object} tileBoundingVolume The volume to determine the intersection with the planes.
   * @param {Matrix4} [transform] An optional, additional matrix to transform the plane to world coordinates.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire volume is on the side of the planes
   *                      the normal is pointing and should be entirely rendered, {@link Intersect.OUTSIDE}
   *                      if the entire volume is on the opposite side and should be clipped, and
   *                      {@link Intersect.INTERSECTING} if the volume intersects the planes.
   */
  ClippingPlaneCollection.prototype.computeIntersectionWithBoundingVolume = function (
    tileBoundingVolume,
    transform
  ) {
    var planes = this._planes;
    var length = planes.length;

    var modelMatrix = this.modelMatrix;
    if (defined(transform)) {
      modelMatrix = Matrix4.multiply(transform, modelMatrix, scratchMatrix);
    }

    // If the collection is not set to union the clipping regions, the volume must be outside of all planes to be
    // considered completely clipped. If the collection is set to union the clipping regions, if the volume can be
    // outside any the planes, it is considered completely clipped.
    // Lastly, if not completely clipped, if any plane is intersecting, more calculations must be performed.
    var intersection = Intersect$1.INSIDE;
    if (!this.unionClippingRegions && length > 0) {
      intersection = Intersect$1.OUTSIDE;
    }

    for (var i = 0; i < length; ++i) {
      var plane = planes[i];

      Plane.transform(plane, modelMatrix, scratchPlane$2); // ClippingPlane can be used for Plane math

      var value = tileBoundingVolume.intersectPlane(scratchPlane$2);
      if (value === Intersect$1.INTERSECTING) {
        intersection = value;
      } else if (this._testIntersection(value)) {
        return value;
      }
    }

    return intersection;
  };

  /**
   * Sets the owner for the input ClippingPlaneCollection if there wasn't another owner.
   * Destroys the owner's previous ClippingPlaneCollection if setting is successful.
   *
   * @param {ClippingPlaneCollection} [clippingPlaneCollection] A ClippingPlaneCollection (or undefined) being attached to an object
   * @param {Object} owner An Object that should receive the new ClippingPlaneCollection
   * @param {String} key The Key for the Object to reference the ClippingPlaneCollection
   * @private
   */
  ClippingPlaneCollection.setOwner = function (
    clippingPlaneCollection,
    owner,
    key
  ) {
    // Don't destroy the ClippingPlaneCollection if it is already owned by newOwner
    if (clippingPlaneCollection === owner[key]) {
      return;
    }
    // Destroy the existing ClippingPlaneCollection, if any
    owner[key] = owner[key] && owner[key].destroy();
    if (defined(clippingPlaneCollection)) {
      //>>includeStart('debug', pragmas.debug);
      if (defined(clippingPlaneCollection._owner)) {
        throw new DeveloperError(
          "ClippingPlaneCollection should only be assigned to one object"
        );
      }
      //>>includeEnd('debug');
      clippingPlaneCollection._owner = owner;
      owner[key] = clippingPlaneCollection;
    }
  };

  /**
   * Function for checking if the context will allow clipping planes with floating point textures.
   *
   * @param {Context} context The Context that will contain clipped objects and clipping textures.
   * @returns {Boolean} <code>true</code> if floating point textures can be used for clipping planes.
   * @private
   */
  ClippingPlaneCollection.useFloatTexture = function (context) {
    return context.floatingPointTexture;
  };

  /**
   * Function for getting the clipping plane collection's texture resolution.
   * If the ClippingPlaneCollection hasn't been updated, returns the resolution that will be
   * allocated based on the current plane count.
   *
   * @param {ClippingPlaneCollection} clippingPlaneCollection The clipping plane collection
   * @param {Context} context The rendering context
   * @param {Cartesian2} result A Cartesian2 for the result.
   * @returns {Cartesian2} The required resolution.
   * @private
   */
  ClippingPlaneCollection.getTextureResolution = function (
    clippingPlaneCollection,
    context,
    result
  ) {
    var texture = clippingPlaneCollection.texture;
    if (defined(texture)) {
      result.x = texture.width;
      result.y = texture.height;
      return result;
    }

    var pixelsNeeded = ClippingPlaneCollection.useFloatTexture(context)
      ? clippingPlaneCollection.length
      : clippingPlaneCollection.length * 2;
    var requiredResolution = computeTextureResolution(pixelsNeeded, result);

    // Allocate twice as much space as needed to avoid frequent texture reallocation.
    requiredResolution.y *= 2;
    return requiredResolution;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see ClippingPlaneCollection#destroy
   */
  ClippingPlaneCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * clippingPlanes = clippingPlanes && clippingPlanes .destroy();
   *
   * @see ClippingPlaneCollection#isDestroyed
   */
  ClippingPlaneCollection.prototype.destroy = function () {
    this._clippingPlanesTexture =
      this._clippingPlanesTexture && this._clippingPlanesTexture.destroy();
    return destroyObject(this);
  };

  /**
   * Defines different modes for blending between a target color and a primitive's source color.
   *
   * HIGHLIGHT multiplies the source color by the target color
   * REPLACE replaces the source color with the target color
   * MIX blends the source color and target color together
   *
   * @enum {Number}
   *
   * @see Model.colorBlendMode
   */
  var ColorBlendMode = {
    HIGHLIGHT: 0,
    REPLACE: 1,
    MIX: 2,
  };

  /**
   * @private
   */
  ColorBlendMode.getColorBlend = function (colorBlendMode, colorBlendAmount) {
    if (colorBlendMode === ColorBlendMode.HIGHLIGHT) {
      return 0.0;
    } else if (colorBlendMode === ColorBlendMode.REPLACE) {
      return 1.0;
    } else if (colorBlendMode === ColorBlendMode.MIX) {
      // The value 0.0 is reserved for highlight, so clamp to just above 0.0.
      return CesiumMath.clamp(colorBlendAmount, CesiumMath.EPSILON4, 1.0);
    }
  };
  var ColorBlendMode$1 = Object.freeze(ColorBlendMode);

  /**
   * @private
   */
  function DracoLoader() {}

  // Maximum concurrency to use when decoding draco models
  DracoLoader._maxDecodingConcurrency = Math.max(
    FeatureDetection.hardwareConcurrency - 1,
    1
  );

  // Exposed for testing purposes
  DracoLoader._decoderTaskProcessor = undefined;
  DracoLoader._taskProcessorReady = false;
  DracoLoader._getDecoderTaskProcessor = function () {
    if (!defined(DracoLoader._decoderTaskProcessor)) {
      var processor = new TaskProcessor(
        "decodeDraco",
        DracoLoader._maxDecodingConcurrency
      );
      processor
        .initWebAssemblyModule({
          modulePath: "ThirdParty/Workers/draco_wasm_wrapper.js",
          wasmBinaryFile: "ThirdParty/draco_decoder.wasm",
          fallbackModulePath: "ThirdParty/Workers/draco_decoder.js",
        })
        .then(function () {
          DracoLoader._taskProcessorReady = true;
        });
      DracoLoader._decoderTaskProcessor = processor;
    }

    return DracoLoader._decoderTaskProcessor;
  };

  /**
   * Returns true if the model uses or requires KHR_draco_mesh_compression.
   *
   * @private
   */
  DracoLoader.hasExtension = function (model) {
    return (
      defined(model.extensionsRequired.KHR_draco_mesh_compression) ||
      defined(model.extensionsUsed.KHR_draco_mesh_compression)
    );
  };

  function addBufferToLoadResources(loadResources, typedArray) {
    // Create a new id to differentiate from original glTF bufferViews
    var bufferViewId =
      "runtime." + Object.keys(loadResources.createdBufferViews).length;

    var loadResourceBuffers = loadResources.buffers;
    var id = Object.keys(loadResourceBuffers).length;
    loadResourceBuffers[id] = typedArray;
    loadResources.createdBufferViews[bufferViewId] = {
      buffer: id,
      byteOffset: 0,
      byteLength: typedArray.byteLength,
    };

    return bufferViewId;
  }

  function addNewVertexBuffer(typedArray, model, context) {
    var loadResources = model._loadResources;
    var id = addBufferToLoadResources(loadResources, typedArray);
    loadResources.vertexBuffersToCreate.enqueue(id);
    return id;
  }

  function addNewIndexBuffer(indexArray, model, context) {
    var typedArray = indexArray.typedArray;
    var loadResources = model._loadResources;
    var id = addBufferToLoadResources(loadResources, typedArray);
    loadResources.indexBuffersToCreate.enqueue({
      id: id,
      componentType: ComponentDatatype$1.fromTypedArray(typedArray),
    });

    return {
      bufferViewId: id,
      numberOfIndices: indexArray.numberOfIndices,
    };
  }

  function scheduleDecodingTask(
    decoderTaskProcessor,
    model,
    loadResources,
    context
  ) {
    if (!DracoLoader._taskProcessorReady) {
      // The task processor is not ready to schedule tasks
      return;
    }

    var taskData = loadResources.primitivesToDecode.peek();
    if (!defined(taskData)) {
      // All primitives are processing
      return;
    }

    var promise = decoderTaskProcessor.scheduleTask(taskData, [
      taskData.array.buffer,
    ]);
    if (!defined(promise)) {
      // Cannot schedule another task this frame
      return;
    }

    loadResources.activeDecodingTasks++;
    loadResources.primitivesToDecode.dequeue();
    return promise.then(function (result) {
      loadResources.activeDecodingTasks--;

      var decodedIndexBuffer = addNewIndexBuffer(
        result.indexArray,
        model);

      var attributes = {};
      var decodedAttributeData = result.attributeData;
      for (var attributeName in decodedAttributeData) {
        if (decodedAttributeData.hasOwnProperty(attributeName)) {
          var attribute = decodedAttributeData[attributeName];
          var vertexArray = attribute.array;
          var vertexBufferView = addNewVertexBuffer(vertexArray, model);

          var data = attribute.data;
          data.bufferView = vertexBufferView;

          attributes[attributeName] = data;
        }
      }

      model._decodedData[taskData.mesh + ".primitive." + taskData.primitive] = {
        bufferView: decodedIndexBuffer.bufferViewId,
        numberOfIndices: decodedIndexBuffer.numberOfIndices,
        attributes: attributes,
      };
    });
  }

  DracoLoader._decodedModelResourceCache = undefined;

  /**
   * Parses draco extension on model primitives and
   * adds the decoding data to the model's load resources.
   *
   * @private
   */
  DracoLoader.parse = function (model, context) {
    if (!DracoLoader.hasExtension(model)) {
      return;
    }

    var loadResources = model._loadResources;
    var cacheKey = model.cacheKey;
    if (defined(cacheKey)) {
      if (!defined(DracoLoader._decodedModelResourceCache)) {
        if (!defined(context.cache.modelDecodingCache)) {
          context.cache.modelDecodingCache = {};
        }

        DracoLoader._decodedModelResourceCache = context.cache.modelDecodingCache;
      }

      // Decoded data for model will be loaded from cache
      var cachedData = DracoLoader._decodedModelResourceCache[cacheKey];
      if (defined(cachedData)) {
        cachedData.count++;
        loadResources.pendingDecodingCache = true;
        return;
      }
    }

    var dequantizeInShader = model._dequantizeInShader;
    var gltf = model.gltf;
    ForEach.mesh(gltf, function (mesh, meshId) {
      ForEach.meshPrimitive(mesh, function (primitive, primitiveId) {
        if (!defined(primitive.extensions)) {
          return;
        }

        var compressionData = primitive.extensions.KHR_draco_mesh_compression;
        if (!defined(compressionData)) {
          return;
        }

        var bufferView = gltf.bufferViews[compressionData.bufferView];
        var typedArray = arraySlice(
          gltf.buffers[bufferView.buffer].extras._pipeline.source,
          bufferView.byteOffset,
          bufferView.byteOffset + bufferView.byteLength
        );
        loadResources.primitivesToDecode.enqueue({
          mesh: meshId,
          primitive: primitiveId,
          array: typedArray,
          bufferView: bufferView,
          compressedAttributes: compressionData.attributes,
          dequantizeInShader: dequantizeInShader,
        });
      });
    });
  };

  /**
   * Schedules decoding tasks available this frame.
   * @private
   */
  DracoLoader.decodeModel = function (model, context) {
    if (!DracoLoader.hasExtension(model)) {
      return when.resolve();
    }

    var loadResources = model._loadResources;
    var cacheKey = model.cacheKey;
    if (defined(cacheKey) && defined(DracoLoader._decodedModelResourceCache)) {
      var cachedData = DracoLoader._decodedModelResourceCache[cacheKey];
      // Load decoded data for model when cache is ready
      if (defined(cachedData) && loadResources.pendingDecodingCache) {
        return when(cachedData.ready, function () {
          model._decodedData = cachedData.data;
          loadResources.pendingDecodingCache = false;
        });
      }

      // Decoded data for model should be cached when ready
      DracoLoader._decodedModelResourceCache[cacheKey] = {
        ready: false,
        count: 1,
        data: undefined,
      };
    }

    if (loadResources.primitivesToDecode.length === 0) {
      // No more tasks to schedule
      return when.resolve();
    }

    var decoderTaskProcessor = DracoLoader._getDecoderTaskProcessor();
    var decodingPromises = [];

    var promise = scheduleDecodingTask(
      decoderTaskProcessor,
      model,
      loadResources);
    while (defined(promise)) {
      decodingPromises.push(promise);
      promise = scheduleDecodingTask(
        decoderTaskProcessor,
        model,
        loadResources);
    }

    return when.all(decodingPromises);
  };

  /**
   * Decodes a compressed point cloud. Returns undefined if the task cannot be scheduled.
   * @private
   */
  DracoLoader.decodePointCloud = function (parameters) {
    var decoderTaskProcessor = DracoLoader._getDecoderTaskProcessor();
    if (!DracoLoader._taskProcessorReady) {
      // The task processor is not ready to schedule tasks
      return;
    }
    return decoderTaskProcessor.scheduleTask(parameters, [
      parameters.buffer.buffer,
    ]);
  };

  /**
   * Caches a models decoded data so it doesn't need to decode more than once.
   * @private
   */
  DracoLoader.cacheDataForModel = function (model) {
    var cacheKey = model.cacheKey;
    if (defined(cacheKey) && defined(DracoLoader._decodedModelResourceCache)) {
      var cachedData = DracoLoader._decodedModelResourceCache[cacheKey];
      if (defined(cachedData)) {
        cachedData.ready = true;
        cachedData.data = model._decodedData;
      }
    }
  };

  /**
   * Destroys the cached data that this model references if it is no longer in use.
   * @private
   */
  DracoLoader.destroyCachedDataForModel = function (model) {
    var cacheKey = model.cacheKey;
    if (defined(cacheKey) && defined(DracoLoader._decodedModelResourceCache)) {
      var cachedData = DracoLoader._decodedModelResourceCache[cacheKey];
      if (defined(cachedData) && --cachedData.count === 0) {
        delete DracoLoader._decodedModelResourceCache[cacheKey];
      }
    }
  };

  /**
   * Gets a GLSL snippet that clips a fragment using the `clip` function from {@link getClippingFunction} and styles it.
   *
   * @param {String} samplerUniformName Name of the uniform for the clipping planes texture sampler.
   * @param {String} matrixUniformName Name of the uniform for the clipping planes matrix.
   * @param {String} styleUniformName Name of the uniform for the clipping planes style, a vec4.
   * @returns {String} A string containing GLSL that clips and styles the current fragment.
   * @private
   */
  function getClipAndStyleCode(
    samplerUniformName,
    matrixUniformName,
    styleUniformName
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("samplerUniformName", samplerUniformName);
    Check.typeOf.string("matrixUniformName", matrixUniformName);
    Check.typeOf.string("styleUniformName", styleUniformName);
    //>>includeEnd('debug');

    var shaderCode =
      "    float clipDistance = clip(gl_FragCoord, " +
      samplerUniformName +
      ", " +
      matrixUniformName +
      "); \n" +
      "    vec4 clippingPlanesEdgeColor = vec4(1.0); \n" +
      "    clippingPlanesEdgeColor.rgb = " +
      styleUniformName +
      ".rgb; \n" +
      "    float clippingPlanesEdgeWidth = " +
      styleUniformName +
      ".a; \n" +
      "    if (clipDistance > 0.0 && clipDistance < clippingPlanesEdgeWidth) \n" +
      "    { \n" +
      "        gl_FragColor = clippingPlanesEdgeColor;\n" +
      "    } \n";
    return shaderCode;
  }

  var textureResolutionScratch$1 = new Cartesian2();
  /**
   * Gets the GLSL functions needed to retrieve clipping planes from a ClippingPlaneCollection's texture.
   *
   * @param {ClippingPlaneCollection} clippingPlaneCollection ClippingPlaneCollection with a defined texture.
   * @param {Context} context The current rendering context.
   * @returns {String} A string containing GLSL functions for retrieving clipping planes.
   * @private
   */
  function getClippingFunction(clippingPlaneCollection, context) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("clippingPlaneCollection", clippingPlaneCollection);
    Check.typeOf.object("context", context);
    //>>includeEnd('debug');
    var unionClippingRegions = clippingPlaneCollection.unionClippingRegions;
    var clippingPlanesLength = clippingPlaneCollection.length;
    var usingFloatTexture = ClippingPlaneCollection.useFloatTexture(context);
    var textureResolution = ClippingPlaneCollection.getTextureResolution(
      clippingPlaneCollection,
      context,
      textureResolutionScratch$1
    );
    var width = textureResolution.x;
    var height = textureResolution.y;

    var functions = usingFloatTexture
      ? getClippingPlaneFloat(width, height)
      : getClippingPlaneUint8(width, height);
    functions += "\n";
    functions += unionClippingRegions
      ? clippingFunctionUnion(clippingPlanesLength)
      : clippingFunctionIntersect(clippingPlanesLength);
    return functions;
  }

  function clippingFunctionUnion(clippingPlanesLength) {
    var functionString =
      "float clip(vec4 fragCoord, sampler2D clippingPlanes, mat4 clippingPlanesMatrix)\n" +
      "{\n" +
      "    vec4 position = czm_windowToEyeCoordinates(fragCoord);\n" +
      "    vec3 clipNormal = vec3(0.0);\n" +
      "    vec3 clipPosition = vec3(0.0);\n" +
      "    float clipAmount;\n" + // For union planes, we want to get the min distance. So we set the initial value to the first plane distance in the loop below.
      "    float pixelWidth = czm_metersPerPixel(position);\n" +
      "    bool breakAndDiscard = false;\n" +
      "    for (int i = 0; i < " +
      clippingPlanesLength +
      "; ++i)\n" +
      "    {\n" +
      "        vec4 clippingPlane = getClippingPlane(clippingPlanes, i, clippingPlanesMatrix);\n" +
      "        clipNormal = clippingPlane.xyz;\n" +
      "        clipPosition = -clippingPlane.w * clipNormal;\n" +
      "        float amount = dot(clipNormal, (position.xyz - clipPosition)) / pixelWidth;\n" +
      "        clipAmount = czm_branchFreeTernary(i == 0, amount, min(amount, clipAmount));\n" +
      "        if (amount <= 0.0)\n" +
      "        {\n" +
      "           breakAndDiscard = true;\n" +
      "           break;\n" + // HLSL compiler bug if we discard here: https://bugs.chromium.org/p/angleproject/issues/detail?id=1945#c6
      "        }\n" +
      "    }\n" +
      "    if (breakAndDiscard) {\n" +
      "        discard;\n" +
      "    }\n" +
      "    return clipAmount;\n" +
      "}\n";
    return functionString;
  }

  function clippingFunctionIntersect(clippingPlanesLength) {
    var functionString =
      "float clip(vec4 fragCoord, sampler2D clippingPlanes, mat4 clippingPlanesMatrix)\n" +
      "{\n" +
      "    bool clipped = true;\n" +
      "    vec4 position = czm_windowToEyeCoordinates(fragCoord);\n" +
      "    vec3 clipNormal = vec3(0.0);\n" +
      "    vec3 clipPosition = vec3(0.0);\n" +
      "    float clipAmount = 0.0;\n" +
      "    float pixelWidth = czm_metersPerPixel(position);\n" +
      "    for (int i = 0; i < " +
      clippingPlanesLength +
      "; ++i)\n" +
      "    {\n" +
      "        vec4 clippingPlane = getClippingPlane(clippingPlanes, i, clippingPlanesMatrix);\n" +
      "        clipNormal = clippingPlane.xyz;\n" +
      "        clipPosition = -clippingPlane.w * clipNormal;\n" +
      "        float amount = dot(clipNormal, (position.xyz - clipPosition)) / pixelWidth;\n" +
      "        clipAmount = max(amount, clipAmount);\n" +
      "        clipped = clipped && (amount <= 0.0);\n" +
      "    }\n" +
      "    if (clipped)\n" +
      "    {\n" +
      "        discard;\n" +
      "    }\n" +
      "    return clipAmount;\n" +
      "}\n";
    return functionString;
  }

  function getClippingPlaneFloat(width, height) {
    var pixelWidth = 1.0 / width;
    var pixelHeight = 1.0 / height;

    var pixelWidthString = pixelWidth + "";
    if (pixelWidthString.indexOf(".") === -1) {
      pixelWidthString += ".0";
    }
    var pixelHeightString = pixelHeight + "";
    if (pixelHeightString.indexOf(".") === -1) {
      pixelHeightString += ".0";
    }

    var functionString =
      "vec4 getClippingPlane(highp sampler2D packedClippingPlanes, int clippingPlaneNumber, mat4 transform)\n" +
      "{\n" +
      "    int pixY = clippingPlaneNumber / " +
      width +
      ";\n" +
      "    int pixX = clippingPlaneNumber - (pixY * " +
      width +
      ");\n" +
      "    float u = (float(pixX) + 0.5) * " +
      pixelWidthString +
      ";\n" + // sample from center of pixel
      "    float v = (float(pixY) + 0.5) * " +
      pixelHeightString +
      ";\n" +
      "    vec4 plane = texture2D(packedClippingPlanes, vec2(u, v));\n" +
      "    return czm_transformPlane(plane, transform);\n" +
      "}\n";
    return functionString;
  }

  function getClippingPlaneUint8(width, height) {
    var pixelWidth = 1.0 / width;
    var pixelHeight = 1.0 / height;

    var pixelWidthString = pixelWidth + "";
    if (pixelWidthString.indexOf(".") === -1) {
      pixelWidthString += ".0";
    }
    var pixelHeightString = pixelHeight + "";
    if (pixelHeightString.indexOf(".") === -1) {
      pixelHeightString += ".0";
    }

    var functionString =
      "vec4 getClippingPlane(highp sampler2D packedClippingPlanes, int clippingPlaneNumber, mat4 transform)\n" +
      "{\n" +
      "    int clippingPlaneStartIndex = clippingPlaneNumber * 2;\n" + // clipping planes are two pixels each
      "    int pixY = clippingPlaneStartIndex / " +
      width +
      ";\n" +
      "    int pixX = clippingPlaneStartIndex - (pixY * " +
      width +
      ");\n" +
      "    float u = (float(pixX) + 0.5) * " +
      pixelWidthString +
      ";\n" + // sample from center of pixel
      "    float v = (float(pixY) + 0.5) * " +
      pixelHeightString +
      ";\n" +
      "    vec4 oct32 = texture2D(packedClippingPlanes, vec2(u, v)) * 255.0;\n" +
      "    vec2 oct = vec2(oct32.x * 256.0 + oct32.y, oct32.z * 256.0 + oct32.w);\n" +
      "    vec4 plane;\n" +
      "    plane.xyz = czm_octDecode(oct, 65535.0);\n" +
      "    plane.w = czm_unpackFloat(texture2D(packedClippingPlanes, vec2(u + " +
      pixelWidthString +
      ", v)));\n" +
      "    return czm_transformPlane(plane, transform);\n" +
      "}\n";
    return functionString;
  }

  /**
   * @private
   */
  var JobType = {
    TEXTURE: 0,
    PROGRAM: 1,
    BUFFER: 2,
    NUMBER_OF_JOB_TYPES: 3,
  };
  var JobType$1 = Object.freeze(JobType);

  /**
   * @private
   */
  function ModelAnimationCache() {}

  var dataUriRegex$2 = /^data\:/i;

  function getAccessorKey(model, accessor) {
    var gltf = model.gltf;
    var buffers = gltf.buffers;
    var bufferViews = gltf.bufferViews;

    var bufferView = bufferViews[accessor.bufferView];
    var buffer = buffers[bufferView.buffer];

    var byteOffset = bufferView.byteOffset + accessor.byteOffset;
    var byteLength = accessor.count * numberOfComponentsForType(accessor.type);

    var uriKey = dataUriRegex$2.test(buffer.uri) ? "" : buffer.uri;
    return model.cacheKey + "//" + uriKey + "/" + byteOffset + "/" + byteLength;
  }

  var cachedAnimationParameters = {};

  ModelAnimationCache.getAnimationParameterValues = function (model, accessor) {
    var key = getAccessorKey(model, accessor);
    var values = cachedAnimationParameters[key];

    if (!defined(values)) {
      // Cache miss
      var gltf = model.gltf;

      var buffers = gltf.buffers;
      var bufferViews = gltf.bufferViews;

      var bufferView = bufferViews[accessor.bufferView];
      var bufferId = bufferView.buffer;
      var buffer = buffers[bufferId];
      var source = buffer.extras._pipeline.source;

      var componentType = accessor.componentType;
      var type = accessor.type;
      var numberOfComponents = numberOfComponentsForType(type);
      var count = accessor.count;
      var byteStride = getAccessorByteStride(gltf, accessor);

      values = new Array(count);
      var accessorByteOffset = defaultValue(accessor.byteOffset, 0);
      var byteOffset = bufferView.byteOffset + accessorByteOffset;
      for (var i = 0; i < count; i++) {
        var typedArrayView = ComponentDatatype$1.createArrayBufferView(
          componentType,
          source.buffer,
          source.byteOffset + byteOffset,
          numberOfComponents
        );
        if (type === "SCALAR") {
          values[i] = typedArrayView[0];
        } else if (type === "VEC3") {
          values[i] = Cartesian3.fromArray(typedArrayView);
        } else if (type === "VEC4") {
          values[i] = Quaternion.unpack(typedArrayView);
        }
        byteOffset += byteStride;
      }
      // GLTF_SPEC: Support more parameter types when glTF supports targeting materials. https://github.com/KhronosGroup/glTF/issues/142

      if (defined(model.cacheKey)) {
        // Only cache when we can create a unique id
        cachedAnimationParameters[key] = values;
      }
    }

    return values;
  };

  var cachedAnimationSplines = {};

  function getAnimationSplineKey(model, animationName, samplerName) {
    return model.cacheKey + "//" + animationName + "/" + samplerName;
  }

  function ConstantSpline(value) {
    this._value = value;
  }
  ConstantSpline.prototype.evaluate = function (time, result) {
    return this._value;
  };
  ConstantSpline.prototype.wrapTime = function (time) {
    return 0.0;
  };
  ConstantSpline.prototype.clampTime = function (time) {
    return 0.0;
  };

  function SteppedSpline(backingSpline) {
    this._spline = backingSpline;
    this._lastTimeIndex = 0;
  }
  SteppedSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;
  SteppedSpline.prototype.evaluate = function (time, result) {
    var i = (this._lastTimeIndex = this.findTimeInterval(
      time,
      this._lastTimeIndex
    ));
    var times = this._spline.times;
    var steppedTime = time >= times[i + 1] ? times[i + 1] : times[i];
    return this._spline.evaluate(steppedTime, result);
  };
  Object.defineProperties(SteppedSpline.prototype, {
    times: {
      get: function () {
        return this._spline.times;
      },
    },
  });
  SteppedSpline.prototype.wrapTime = function (time) {
    return this._spline.wrapTime(time);
  };
  SteppedSpline.prototype.clampTime = function (time) {
    return this._spline.clampTime(time);
  };

  ModelAnimationCache.getAnimationSpline = function (
    model,
    animationName,
    animation,
    samplerName,
    sampler,
    input,
    path,
    output
  ) {
    var key = getAnimationSplineKey(model, animationName, samplerName);
    var spline = cachedAnimationSplines[key];

    if (!defined(spline)) {
      var times = input;
      var controlPoints = output;

      if (times.length === 1 && controlPoints.length === 1) {
        spline = new ConstantSpline(controlPoints[0]);
      } else if (
        sampler.interpolation === "LINEAR" ||
        sampler.interpolation === "STEP"
      ) {
        if (path === "translation" || path === "scale") {
          spline = new LinearSpline({
            times: times,
            points: controlPoints,
          });
        } else if (path === "rotation") {
          spline = new QuaternionSpline({
            times: times,
            points: controlPoints,
          });
        } else if (path === "weights") {
          spline = new WeightSpline({
            times: times,
            weights: controlPoints,
          });
        }

        if (defined(spline) && sampler.interpolation === "STEP") {
          spline = new SteppedSpline(spline);
        }
      }

      if (defined(model.cacheKey)) {
        // Only cache when we can create a unique id
        cachedAnimationSplines[key] = spline;
      }
    }

    return spline;
  };

  var cachedSkinInverseBindMatrices = {};

  ModelAnimationCache.getSkinInverseBindMatrices = function (model, accessor) {
    var key = getAccessorKey(model, accessor);
    var matrices = cachedSkinInverseBindMatrices[key];

    if (!defined(matrices)) {
      // Cache miss
      var gltf = model.gltf;
      var buffers = gltf.buffers;
      var bufferViews = gltf.bufferViews;

      var bufferViewId = accessor.bufferView;
      var bufferView = bufferViews[bufferViewId];
      var bufferId = bufferView.buffer;
      var buffer = buffers[bufferId];
      var source = buffer.extras._pipeline.source;

      var componentType = accessor.componentType;
      var type = accessor.type;
      var count = accessor.count;
      var byteStride = getAccessorByteStride(gltf, accessor);
      var byteOffset = bufferView.byteOffset + accessor.byteOffset;
      var numberOfComponents = numberOfComponentsForType(type);

      matrices = new Array(count);

      if (componentType === WebGLConstants$1.FLOAT && type === AttributeType$1.MAT4) {
        for (var i = 0; i < count; ++i) {
          var typedArrayView = ComponentDatatype$1.createArrayBufferView(
            componentType,
            source.buffer,
            source.byteOffset + byteOffset,
            numberOfComponents
          );
          matrices[i] = Matrix4.fromArray(typedArrayView);
          byteOffset += byteStride;
        }
      }

      cachedSkinInverseBindMatrices[key] = matrices;
    }

    return matrices;
  };

  /**
   * Determines if and how a glTF animation is looped.
   *
   * @enum {Number}
   *
   * @see ModelAnimationCollection#add
   */
  var ModelAnimationLoop = {
    /**
     * Play the animation once; do not loop it.
     *
     * @type {Number}
     * @constant
     */
    NONE: 0,

    /**
     * Loop the animation playing it from the start immediately after it stops.
     *
     * @type {Number}
     * @constant
     */
    REPEAT: 1,

    /**
     * Loop the animation.  First, playing it forward, then in reverse, then forward, and so on.
     *
     * @type {Number}
     * @constant
     */
    MIRRORED_REPEAT: 2,
  };
  var ModelAnimationLoop$1 = Object.freeze(ModelAnimationLoop);

  /**
   * @private
   */
  var ModelAnimationState = Object.freeze({
    STOPPED: 0,
    ANIMATING: 1,
  });

  /**
   * An active glTF animation.  A glTF asset can contain animations.  An active animation
   * is an animation that is currently playing or scheduled to be played because it was
   * added to a model's {@link ModelAnimationCollection}.  An active animation is an
   * instance of an animation; for example, there can be multiple active animations
   * for the same glTF animation, each with a different start time.
   * <p>
   * Create this by calling {@link ModelAnimationCollection#add}.
   * </p>
   *
   * @alias ModelAnimation
   * @internalConstructor
   * @class
   *
   * @see ModelAnimationCollection#add
   */
  function ModelAnimation(options, model, runtimeAnimation) {
    this._name = runtimeAnimation.name;
    this._startTime = JulianDate.clone(options.startTime);
    this._delay = defaultValue(options.delay, 0.0); // in seconds
    this._stopTime = options.stopTime;

    /**
     * When <code>true</code>, the animation is removed after it stops playing.
     * This is slightly more efficient that not removing it, but if, for example,
     * time is reversed, the animation is not played again.
     *
     * @type {Boolean}
     * @default false
     */
    this.removeOnStop = defaultValue(options.removeOnStop, false);
    this._multiplier = defaultValue(options.multiplier, 1.0);
    this._reverse = defaultValue(options.reverse, false);
    this._loop = defaultValue(options.loop, ModelAnimationLoop$1.NONE);

    /**
     * The event fired when this animation is started.  This can be used, for
     * example, to play a sound or start a particle system, when the animation starts.
     * <p>
     * This event is fired at the end of the frame after the scene is rendered.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * animation.start.addEventListener(function(model, animation) {
     *   console.log('Animation started: ' + animation.name);
     * });
     */
    this.start = new Event();

    /**
     * The event fired when on each frame when this animation is updated.  The
     * current time of the animation, relative to the glTF animation time span, is
     * passed to the event, which allows, for example, starting new animations at a
     * specific time relative to a playing animation.
     * <p>
     * This event is fired at the end of the frame after the scene is rendered.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * animation.update.addEventListener(function(model, animation, time) {
     *   console.log('Animation updated: ' + animation.name + '. glTF animation time: ' + time);
     * });
     */
    this.update = new Event();

    /**
     * The event fired when this animation is stopped.  This can be used, for
     * example, to play a sound or start a particle system, when the animation stops.
     * <p>
     * This event is fired at the end of the frame after the scene is rendered.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * animation.stop.addEventListener(function(model, animation) {
     *   console.log('Animation stopped: ' + animation.name);
     * });
     */
    this.stop = new Event();

    this._state = ModelAnimationState.STOPPED;
    this._runtimeAnimation = runtimeAnimation;

    // Set during animation update
    this._computedStartTime = undefined;
    this._duration = undefined;

    // To avoid allocations in ModelAnimationCollection.update
    var that = this;
    this._raiseStartEvent = function () {
      that.start.raiseEvent(model, that);
    };
    this._updateEventTime = 0.0;
    this._raiseUpdateEvent = function () {
      that.update.raiseEvent(model, that, that._updateEventTime);
    };
    this._raiseStopEvent = function () {
      that.stop.raiseEvent(model, that);
    };
  }

  Object.defineProperties(ModelAnimation.prototype, {
    /**
     * The glTF animation name that identifies this animation.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },

    /**
     * The scene time to start playing this animation.  When this is <code>undefined</code>,
     * the animation starts at the next frame.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {JulianDate}
     * @readonly
     *
     * @default undefined
     */
    startTime: {
      get: function () {
        return this._startTime;
      },
    },

    /**
     * The delay, in seconds, from {@link ModelAnimation#startTime} to start playing.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @default undefined
     */
    delay: {
      get: function () {
        return this._delay;
      },
    },

    /**
     * The scene time to stop playing this animation.  When this is <code>undefined</code>,
     * the animation is played for its full duration and perhaps repeated depending on
     * {@link ModelAnimation#loop}.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {JulianDate}
     * @readonly
     *
     * @default undefined
     */
    stopTime: {
      get: function () {
        return this._stopTime;
      },
    },
    /**
     * Values greater than <code>1.0</code> increase the speed that the animation is played relative
     * to the scene clock speed; values less than <code>1.0</code> decrease the speed.  A value of
     * <code>1.0</code> plays the animation at the speed in the glTF animation mapped to the scene
     * clock speed.  For example, if the scene is played at 2x real-time, a two-second glTF animation
     * will play in one second even if <code>multiplier</code> is <code>1.0</code>.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @default 1.0
     */
    multiplier: {
      get: function () {
        return this._multiplier;
      },
    },

    /**
     * When <code>true</code>, the animation is played in reverse.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    reverse: {
      get: function () {
        return this._reverse;
      },
    },

    /**
     * Determines if and how the animation is looped.
     *
     * @memberof ModelAnimation.prototype
     *
     * @type {ModelAnimationLoop}
     * @readonly
     *
     * @default {@link ModelAnimationLoop.NONE}
     */
    loop: {
      get: function () {
        return this._loop;
      },
    },
  });

  /**
   * A collection of active model animations.  Access this using {@link Model#activeAnimations}.
   *
   * @alias ModelAnimationCollection
   * @internalConstructor
   * @class
   *
   * @see Model#activeAnimations
   */
  function ModelAnimationCollection(model) {
    /**
     * The event fired when an animation is added to the collection.  This can be used, for
     * example, to keep a UI in sync.
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * model.activeAnimations.animationAdded.addEventListener(function(model, animation) {
     *   console.log('Animation added: ' + animation.name);
     * });
     */
    this.animationAdded = new Event();

    /**
     * The event fired when an animation is removed from the collection.  This can be used, for
     * example, to keep a UI in sync.
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * model.activeAnimations.animationRemoved.addEventListener(function(model, animation) {
     *   console.log('Animation removed: ' + animation.name);
     * });
     */
    this.animationRemoved = new Event();

    this._model = model;
    this._scheduledAnimations = [];
    this._previousTime = undefined;
  }

  Object.defineProperties(ModelAnimationCollection.prototype, {
    /**
     * The number of animations in the collection.
     *
     * @memberof ModelAnimationCollection.prototype
     *
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._scheduledAnimations.length;
      },
    },
  });

  function add(collection, index, options) {
    var model = collection._model;
    var animations = model._runtime.animations;
    var animation = animations[index];
    var scheduledAnimation = new ModelAnimation(options, model, animation);
    collection._scheduledAnimations.push(scheduledAnimation);
    collection.animationAdded.raiseEvent(model, scheduledAnimation);
    return scheduledAnimation;
  }

  /**
   * Creates and adds an animation with the specified initial properties to the collection.
   * <p>
   * This raises the {@link ModelAnimationCollection#animationAdded} event so, for example, a UI can stay in sync.
   * </p>
   *
   * @param {Object} options Object with the following properties:
   * @param {String} [options.name] The glTF animation name that identifies the animation. Must be defined if <code>options.index</code> is <code>undefined</code>.
   * @param {Number} [options.index] The glTF animation index that identifies the animation. Must be defined if <code>options.name</code> is <code>undefined</code>.
   * @param {JulianDate} [options.startTime] The scene time to start playing the animation.  When this is <code>undefined</code>, the animation starts at the next frame.
   * @param {Number} [options.delay=0.0] The delay, in seconds, from <code>startTime</code> to start playing.
   * @param {JulianDate} [options.stopTime] The scene time to stop playing the animation.  When this is <code>undefined</code>, the animation is played for its full duration.
   * @param {Boolean} [options.removeOnStop=false] When <code>true</code>, the animation is removed after it stops playing.
   * @param {Number} [options.multiplier=1.0] Values greater than <code>1.0</code> increase the speed that the animation is played relative to the scene clock speed; values less than <code>1.0</code> decrease the speed.
   * @param {Boolean} [options.reverse=false] When <code>true</code>, the animation is played in reverse.
   * @param {ModelAnimationLoop} [options.loop=ModelAnimationLoop.NONE] Determines if and how the animation is looped.
   * @returns {ModelAnimation} The animation that was added to the collection.
   *
   * @exception {DeveloperError} Animations are not loaded.  Wait for the {@link Model#readyPromise} to resolve.
   * @exception {DeveloperError} options.name must be a valid animation name.
   * @exception {DeveloperError} options.index must be a valid animation index.
   * @exception {DeveloperError} Either options.name or options.index must be defined.
   * @exception {DeveloperError} options.multiplier must be greater than zero.
   *
   * @example
   * // Example 1. Add an animation by name
   * model.activeAnimations.add({
   *   name : 'animation name'
   * });
   *
   * // Example 2. Add an animation by index
   * model.activeAnimations.add({
   *   index : 0
   * });
   *
   * @example
   * // Example 3. Add an animation and provide all properties and events
   * var startTime = Cesium.JulianDate.now();
   *
   * var animation = model.activeAnimations.add({
   *   name : 'another animation name',
   *   startTime : startTime,
   *   delay : 0.0,                          // Play at startTime (default)
   *   stopTime : Cesium.JulianDate.addSeconds(startTime, 4.0, new Cesium.JulianDate()),
   *   removeOnStop : false,                 // Do not remove when animation stops (default)
   *   multiplier : 2.0,                        // Play at double speed
   *   reverse : true,                       // Play in reverse
   *   loop : Cesium.ModelAnimationLoop.REPEAT      // Loop the animation
   * });
   *
   * animation.start.addEventListener(function(model, animation) {
   *   console.log('Animation started: ' + animation.name);
   * });
   * animation.update.addEventListener(function(model, animation, time) {
   *   console.log('Animation updated: ' + animation.name + '. glTF animation time: ' + time);
   * });
   * animation.stop.addEventListener(function(model, animation) {
   *   console.log('Animation stopped: ' + animation.name);
   * });
   */
  ModelAnimationCollection.prototype.add = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var model = this._model;
    var animations = model._runtime.animations;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(animations)) {
      throw new DeveloperError(
        "Animations are not loaded.  Wait for Model.readyPromise to resolve."
      );
    }
    if (!defined(options.name) && !defined(options.index)) {
      throw new DeveloperError(
        "Either options.name or options.index must be defined."
      );
    }

    if (defined(options.multiplier) && options.multiplier <= 0.0) {
      throw new DeveloperError("options.multiplier must be greater than zero.");
    }
    if (
      defined(options.index) &&
      (options.index >= animations.length || options.index < 0)
    ) {
      throw new DeveloperError("options.index must be a valid animation index.");
    }
    //>>includeEnd('debug');

    if (defined(options.index)) {
      return add(this, options.index, options);
    }

    // Find the index of the animation with the given name
    var index;
    var length = animations.length;
    for (var i = 0; i < length; ++i) {
      if (animations[i].name === options.name) {
        index = i;
        break;
      }
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("options.name must be a valid animation name.");
    }
    //>>includeEnd('debug');

    return add(this, index, options);
  };

  /**
   * Creates and adds an animation with the specified initial properties to the collection
   * for each animation in the model.
   * <p>
   * This raises the {@link ModelAnimationCollection#animationAdded} event for each model so, for example, a UI can stay in sync.
   * </p>
   *
   * @param {Object} [options] Object with the following properties:
   * @param {JulianDate} [options.startTime] The scene time to start playing the animations.  When this is <code>undefined</code>, the animations starts at the next frame.
   * @param {Number} [options.delay=0.0] The delay, in seconds, from <code>startTime</code> to start playing.
   * @param {JulianDate} [options.stopTime] The scene time to stop playing the animations.  When this is <code>undefined</code>, the animations are played for its full duration.
   * @param {Boolean} [options.removeOnStop=false] When <code>true</code>, the animations are removed after they stop playing.
   * @param {Number} [options.multiplier=1.0] Values greater than <code>1.0</code> increase the speed that the animations play relative to the scene clock speed; values less than <code>1.0</code> decrease the speed.
   * @param {Boolean} [options.reverse=false] When <code>true</code>, the animations are played in reverse.
   * @param {ModelAnimationLoop} [options.loop=ModelAnimationLoop.NONE] Determines if and how the animations are looped.
   * @returns {ModelAnimation[]} An array of {@link ModelAnimation} objects, one for each animation added to the collection.  If there are no glTF animations, the array is empty.
   *
   * @exception {DeveloperError} Animations are not loaded.  Wait for the {@link Model#readyPromise} to resolve.
   * @exception {DeveloperError} options.multiplier must be greater than zero.
   *
   * @example
   * model.activeAnimations.addAll({
   *   multiplier : 0.5,                        // Play at half-speed
   *   loop : Cesium.ModelAnimationLoop.REPEAT      // Loop the animations
   * });
   */
  ModelAnimationCollection.prototype.addAll = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(this._model._runtime.animations)) {
      throw new DeveloperError(
        "Animations are not loaded.  Wait for Model.readyPromise to resolve."
      );
    }

    if (defined(options.multiplier) && options.multiplier <= 0.0) {
      throw new DeveloperError("options.multiplier must be greater than zero.");
    }
    //>>includeEnd('debug');

    var scheduledAnimations = [];
    var model = this._model;
    var animations = model._runtime.animations;
    var length = animations.length;
    for (var i = 0; i < length; ++i) {
      scheduledAnimations.push(add(this, i, options));
    }
    return scheduledAnimations;
  };

  /**
   * Removes an animation from the collection.
   * <p>
   * This raises the {@link ModelAnimationCollection#animationRemoved} event so, for example, a UI can stay in sync.
   * </p>
   * <p>
   * An animation can also be implicitly removed from the collection by setting {@link ModelAnimation#removeOnStop} to
   * <code>true</code>.  The {@link ModelAnimationCollection#animationRemoved} event is still fired when the animation is removed.
   * </p>
   *
   * @param {ModelAnimation} animation The animation to remove.
   * @returns {Boolean} <code>true</code> if the animation was removed; <code>false</code> if the animation was not found in the collection.
   *
   * @example
   * var a = model.activeAnimations.add({
   *   name : 'animation name'
   * });
   * model.activeAnimations.remove(a); // Returns true
   */
  ModelAnimationCollection.prototype.remove = function (animation) {
    if (defined(animation)) {
      var animations = this._scheduledAnimations;
      var i = animations.indexOf(animation);
      if (i !== -1) {
        animations.splice(i, 1);
        this.animationRemoved.raiseEvent(this._model, animation);
        return true;
      }
    }

    return false;
  };

  /**
   * Removes all animations from the collection.
   * <p>
   * This raises the {@link ModelAnimationCollection#animationRemoved} event for each
   * animation so, for example, a UI can stay in sync.
   * </p>
   */
  ModelAnimationCollection.prototype.removeAll = function () {
    var model = this._model;
    var animations = this._scheduledAnimations;
    var length = animations.length;

    this._scheduledAnimations = [];

    for (var i = 0; i < length; ++i) {
      this.animationRemoved.raiseEvent(model, animations[i]);
    }
  };

  /**
   * Determines whether this collection contains a given animation.
   *
   * @param {ModelAnimation} animation The animation to check for.
   * @returns {Boolean} <code>true</code> if this collection contains the animation, <code>false</code> otherwise.
   */
  ModelAnimationCollection.prototype.contains = function (animation) {
    if (defined(animation)) {
      return this._scheduledAnimations.indexOf(animation) !== -1;
    }

    return false;
  };

  /**
   * Returns the animation in the collection at the specified index.  Indices are zero-based
   * and increase as animations are added.  Removing an animation shifts all animations after
   * it to the left, changing their indices.  This function is commonly used to iterate over
   * all the animations in the collection.
   *
   * @param {Number} index The zero-based index of the animation.
   * @returns {ModelAnimation} The animation at the specified index.
   *
   * @example
   * // Output the names of all the animations in the collection.
   * var animations = model.activeAnimations;
   * var length = animations.length;
   * for (var i = 0; i < length; ++i) {
   *   console.log(animations.get(i).name);
   * }
   */
  ModelAnimationCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    return this._scheduledAnimations[index];
  };

  function animateChannels(runtimeAnimation, localAnimationTime) {
    var channelEvaluators = runtimeAnimation.channelEvaluators;
    var length = channelEvaluators.length;
    for (var i = 0; i < length; ++i) {
      channelEvaluators[i](localAnimationTime);
    }
  }

  var animationsToRemove = [];

  function createAnimationRemovedFunction(
    modelAnimationCollection,
    model,
    animation
  ) {
    return function () {
      modelAnimationCollection.animationRemoved.raiseEvent(model, animation);
    };
  }

  /**
   * @private
   */
  ModelAnimationCollection.prototype.update = function (frameState) {
    var scheduledAnimations = this._scheduledAnimations;
    var length = scheduledAnimations.length;

    if (length === 0) {
      // No animations - quick return for performance
      this._previousTime = undefined;
      return false;
    }

    if (JulianDate.equals(frameState.time, this._previousTime)) {
      // Animations are currently only time-dependent so do not animate when paused or picking
      return false;
    }
    this._previousTime = JulianDate.clone(frameState.time, this._previousTime);

    var animationOccured = false;
    var sceneTime = frameState.time;
    var model = this._model;

    for (var i = 0; i < length; ++i) {
      var scheduledAnimation = scheduledAnimations[i];
      var runtimeAnimation = scheduledAnimation._runtimeAnimation;

      if (!defined(scheduledAnimation._computedStartTime)) {
        scheduledAnimation._computedStartTime = JulianDate.addSeconds(
          defaultValue(scheduledAnimation.startTime, sceneTime),
          scheduledAnimation.delay,
          new JulianDate()
        );
      }

      if (!defined(scheduledAnimation._duration)) {
        scheduledAnimation._duration =
          runtimeAnimation.stopTime * (1.0 / scheduledAnimation.multiplier);
      }

      var startTime = scheduledAnimation._computedStartTime;
      var duration = scheduledAnimation._duration;
      var stopTime = scheduledAnimation.stopTime;

      // [0.0, 1.0] normalized local animation time
      var delta =
        duration !== 0.0
          ? JulianDate.secondsDifference(sceneTime, startTime) / duration
          : 0.0;

      // Clamp delta to stop time, if defined.
      if (
        duration !== 0.0 &&
        defined(stopTime) &&
        JulianDate.greaterThan(sceneTime, stopTime)
      ) {
        delta = JulianDate.secondsDifference(stopTime, startTime) / duration;
      }

      var pastStartTime = delta >= 0.0;

      // Play animation if
      // * we are after the start time or the animation is being repeated, and
      // * before the end of the animation's duration or the animation is being repeated, and
      // * we did not reach a user-provided stop time.

      var repeat =
        scheduledAnimation.loop === ModelAnimationLoop$1.REPEAT ||
        scheduledAnimation.loop === ModelAnimationLoop$1.MIRRORED_REPEAT;

      var play =
        (pastStartTime || (repeat && !defined(scheduledAnimation.startTime))) &&
        (delta <= 1.0 || repeat) &&
        (!defined(stopTime) || JulianDate.lessThanOrEquals(sceneTime, stopTime));

      // If it IS, or WAS, animating...
      if (play || scheduledAnimation._state === ModelAnimationState.ANIMATING) {
        // STOPPED -> ANIMATING state transition?
        if (play && scheduledAnimation._state === ModelAnimationState.STOPPED) {
          scheduledAnimation._state = ModelAnimationState.ANIMATING;
          if (scheduledAnimation.start.numberOfListeners > 0) {
            frameState.afterRender.push(scheduledAnimation._raiseStartEvent);
          }
        }

        // Truncate to [0.0, 1.0] for repeating animations
        if (scheduledAnimation.loop === ModelAnimationLoop$1.REPEAT) {
          delta = delta - Math.floor(delta);
        } else if (
          scheduledAnimation.loop === ModelAnimationLoop$1.MIRRORED_REPEAT
        ) {
          var floor = Math.floor(delta);
          var fract = delta - floor;
          // When even use (1.0 - fract) to mirror repeat
          delta = floor % 2 === 1.0 ? 1.0 - fract : fract;
        }

        if (scheduledAnimation.reverse) {
          delta = 1.0 - delta;
        }

        var localAnimationTime = delta * duration * scheduledAnimation.multiplier;
        // Clamp in case floating-point roundoff goes outside the animation's first or last keyframe
        localAnimationTime = CesiumMath.clamp(
          localAnimationTime,
          runtimeAnimation.startTime,
          runtimeAnimation.stopTime
        );

        animateChannels(runtimeAnimation, localAnimationTime);

        if (scheduledAnimation.update.numberOfListeners > 0) {
          scheduledAnimation._updateEventTime = localAnimationTime;
          frameState.afterRender.push(scheduledAnimation._raiseUpdateEvent);
        }
        animationOccured = true;

        if (!play) {
          // ANIMATING -> STOPPED state transition?
          scheduledAnimation._state = ModelAnimationState.STOPPED;
          if (scheduledAnimation.stop.numberOfListeners > 0) {
            frameState.afterRender.push(scheduledAnimation._raiseStopEvent);
          }

          if (scheduledAnimation.removeOnStop) {
            animationsToRemove.push(scheduledAnimation);
          }
        }
      }
    }

    // Remove animations that stopped
    length = animationsToRemove.length;
    for (var j = 0; j < length; ++j) {
      var animationToRemove = animationsToRemove[j];
      scheduledAnimations.splice(
        scheduledAnimations.indexOf(animationToRemove),
        1
      );
      frameState.afterRender.push(
        createAnimationRemovedFunction(this, model, animationToRemove)
      );
    }
    animationsToRemove.length = 0;

    return animationOccured;
  };

  /**
   * A model's material with modifiable parameters.  A glTF material
   * contains parameters defined by the material's technique with values
   * defined by the technique and potentially overridden by the material.
   * This class allows changing these values at runtime.
   * <p>
   * Use {@link Model#getMaterial} to create an instance.
   * </p>
   *
   * @alias ModelMaterial
   * @internalConstructor
   * @class
   *
   * @see Model#getMaterial
   */
  function ModelMaterial(model, material, id) {
    this._name = material.name;
    this._id = id;
    this._uniformMap = model._uniformMaps[id];

    this._technique = undefined;
    this._program = undefined;
    this._values = undefined;
  }

  Object.defineProperties(ModelMaterial.prototype, {
    /**
     * The value of the <code>name</code> property of this material.
     *
     * @memberof ModelMaterial.prototype
     *
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },

    /**
     * The index of the material.
     *
     * @memberof ModelMaterial.prototype
     *
     * @type {String}
     * @readonly
     */
    id: {
      get: function () {
        return this._id;
      },
    },
  });

  /**
   * Assigns a value to a material parameter.  The type for <code>value</code>
   * depends on the glTF type of the parameter.  It will be a floating-point
   * number, Cartesian, or matrix.
   *
   * @param {String} name The name of the parameter.
   * @param {*} [value] The value to assign to the parameter.
   *
   * @exception {DeveloperError} name must match a parameter name in the material's technique that is targetable and not optimized out.
   *
   * @example
   * material.setValue('diffuse', new Cesium.Cartesian4(1.0, 0.0, 0.0, 1.0));  // vec4
   * material.setValue('shininess', 256.0); // scalar
   */
  ModelMaterial.prototype.setValue = function (name, value) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(name)) {
      throw new DeveloperError("name is required.");
    }
    //>>includeEnd('debug');

    var uniformName = "u_" + name;
    var v = this._uniformMap.values[uniformName];

    //>>includeStart('debug', pragmas.debug);
    if (!defined(v)) {
      throw new DeveloperError(
        "name must match a parameter name in the material's technique that is targetable and not optimized out."
      );
    }
    //>>includeEnd('debug');

    v.value = v.clone(value, v.value);
  };

  /**
   * Returns the value of the parameter with the given <code>name</code>.  The type of the
   * returned object depends on the glTF type of the parameter.  It will be a floating-point
   * number, Cartesian, or matrix.
   *
   * @param {String} name The name of the parameter.
   * @returns {*} The value of the parameter or <code>undefined</code> if the parameter does not exist.
   */
  ModelMaterial.prototype.getValue = function (name) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(name)) {
      throw new DeveloperError("name is required.");
    }
    //>>includeEnd('debug');

    var uniformName = "u_" + name;
    var v = this._uniformMap.values[uniformName];

    if (!defined(v)) {
      return undefined;
    }

    return v.value;
  };

  /**
   * A model's mesh and its materials.
   * <p>
   * Use {@link Model#getMesh} to create an instance.
   * </p>
   *
   * @alias ModelMesh
   * @internalConstructor
   * @class
   *
   * @see Model#getMesh
   */
  function ModelMesh(mesh, runtimeMaterialsById, id) {
    var materials = [];
    var primitives = mesh.primitives;
    var length = primitives.length;
    for (var i = 0; i < length; ++i) {
      var p = primitives[i];
      materials[i] = runtimeMaterialsById[p.material];
    }

    this._name = mesh.name;
    this._materials = materials;
    this._id = id;
  }

  Object.defineProperties(ModelMesh.prototype, {
    /**
     * The value of the <code>name</code> property of this mesh.
     *
     * @memberof ModelMesh.prototype
     *
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },

    /**
     * The index of the mesh.
     *
     * @memberof ModelMesh.prototype
     *
     * @type {String}
     * @readonly
     */
    id: {
      get: function () {
        return this._id;
      },
    },

    /**
     * An array of {@link ModelMaterial} instances indexed by the mesh's
     * primitive indices.
     *
     * @memberof ModelMesh.prototype
     *
     * @type {ModelMaterial[]}
     * @readonly
     */
    materials: {
      get: function () {
        return this._materials;
      },
    },
  });

  /**
   * A model node with a transform for user-defined animations.  A glTF asset can
   * contain animations that target a node's transform.  This class allows
   * changing a node's transform externally so animation can be driven by another
   * source, not just an animation in the glTF asset.
   * <p>
   * Use {@link Model#getNode} to create an instance.
   * </p>
   *
   * @alias ModelNode
   * @internalConstructor
   * @class
   *
   * @example
   * var node = model.getNode('LOD3sp');
   * node.matrix = Cesium.Matrix4.fromScale(new Cesium.Cartesian3(5.0, 1.0, 1.0), node.matrix);
   *
   * @see Model#getNode
   */
  function ModelNode(model, node, runtimeNode, id, matrix) {
    this._model = model;
    this._runtimeNode = runtimeNode;
    this._name = node.name;
    this._id = id;

    /**
     * @private
     */
    this.useMatrix = false;

    this._show = true;
    this._matrix = Matrix4.clone(matrix);
    this._originalMatrix = Matrix4.clone(matrix);
  }

  Object.defineProperties(ModelNode.prototype, {
    /**
     * The value of the <code>name</code> property of this node.
     *
     * @memberof ModelNode.prototype
     *
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },

    /**
     * The index of the node.
     *
     * @memberof ModelNode.prototype
     *
     * @type {String}
     * @readonly
     */
    id: {
      get: function () {
        return this._id;
      },
    },

    /**
     * Determines if this node and its children will be shown.
     *
     * @memberof ModelNode.prototype
     * @type {Boolean}
     *
     * @default true
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        if (this._show !== value) {
          this._show = value;
          this._model._perNodeShowDirty = true;
        }
      },
    },

    /**
     * The node's 4x4 matrix transform from its local coordinates to
     * its parent's.
     * <p>
     * For changes to take effect, this property must be assigned to;
     * setting individual elements of the matrix will not work.
     * </p>
     *
     * @memberof ModelNode.prototype
     * @type {Matrix4}
     */
    matrix: {
      get: function () {
        return this._matrix;
      },
      set: function (value) {
        this._matrix = Matrix4.clone(value, this._matrix);
        this.useMatrix = true;

        var model = this._model;
        model._cesiumAnimationsDirty = true;
        this._runtimeNode.dirtyNumber = model._maxDirtyNumber;
      },
    },

    /**
     * Gets the node's original 4x4 matrix transform from its local coordinates to
     * its parent's, without any node transformations or articulations applied.
     *
     * @memberof ModelNode.prototype
     * @type {Matrix4}
     */
    originalMatrix: {
      get: function () {
        return this._originalMatrix;
      },
    },
  });

  /**
   * @private
   */
  ModelNode.prototype.setMatrix = function (matrix) {
    // Update matrix but do not set the dirty flag since this is used internally
    // to keep the matrix in-sync during a glTF animation.
    Matrix4.clone(matrix, this._matrix);
  };

  // glTF does not allow an index value of 65535 because this is the primitive
  // restart value in some APIs.
  var MAX_GLTF_UINT16_INDEX = 65534;

  /**
   * Creates face outlines for glTF primitives with the `CESIUM_primitive_outline` extension.
   * @private
   */
  function ModelOutlineLoader() {}

  /**
   * Returns true if the model uses or requires CESIUM_primitive_outline.
   * @private
   */
  ModelOutlineLoader.hasExtension = function (model) {
    return (
      defined(model.extensionsRequired.CESIUM_primitive_outline) ||
      defined(model.extensionsUsed.CESIUM_primitive_outline)
    );
  };

  /**
   * Arranges to outline any primitives with the CESIUM_primitive_outline extension.
   * It is expected that all buffer data is loaded and available in
   * `extras._pipeline.source` before this function is called, and that vertex
   * and index WebGL buffers are not yet created.
   * @private
   */
  ModelOutlineLoader.outlinePrimitives = function (model) {
    if (!ModelOutlineLoader.hasExtension(model)) {
      return;
    }

    var gltf = model.gltf;

    // Assumption: A single bufferView contains a single zero-indexed range of vertices.
    // No trickery with using large accessor byteOffsets to store multiple zero-based
    // ranges of vertices in a single bufferView. Use separate bufferViews for that,
    // you monster.
    // Note that interleaved vertex attributes (e.g. position0, normal0, uv0,
    // position1, normal1, uv1, ...) _are_ supported and should not be confused with
    // the above.

    var vertexNumberingScopes = [];

    ForEach.mesh(gltf, function (mesh, meshId) {
      ForEach.meshPrimitive(mesh, function (primitive, primitiveId) {
        if (!defined(primitive.extensions)) {
          return;
        }

        var outlineData = primitive.extensions.CESIUM_primitive_outline;
        if (!defined(outlineData)) {
          return;
        }

        var vertexNumberingScope = getVertexNumberingScope(model, primitive);
        if (vertexNumberingScope === undefined) {
          return;
        }

        if (vertexNumberingScopes.indexOf(vertexNumberingScope) < 0) {
          vertexNumberingScopes.push(vertexNumberingScope);
        }

        // Add the outline to this primitive
        addOutline(
          model,
          meshId,
          primitiveId,
          outlineData.indices,
          vertexNumberingScope
        );
      });
    });

    // Update all relevant bufferViews to include the duplicate vertices that are
    // needed for outlining.
    for (var i = 0; i < vertexNumberingScopes.length; ++i) {
      updateBufferViewsWithNewVertices(
        model,
        vertexNumberingScopes[i].bufferViews
      );
    }

    // Remove data not referenced by any bufferViews anymore.
    compactBuffers(model);
  };

  ModelOutlineLoader.createTexture = function (model, context) {
    var cache = context.cache.modelOutliningCache;
    if (!defined(cache)) {
      cache = context.cache.modelOutliningCache = {};
    }

    if (defined(cache.outlineTexture)) {
      return cache.outlineTexture;
    }

    var maxSize = Math.min(4096, ContextLimits.maximumTextureSize);

    var size = maxSize;
    var levelZero = createTexture$2(size);

    var mipLevels = [];

    while (size > 1) {
      size >>= 1;
      mipLevels.push(createTexture$2(size));
    }

    var texture = new Texture({
      context: context,
      source: {
        arrayBufferView: levelZero,
        mipLevels: mipLevels,
      },
      width: maxSize,
      height: 1,
      pixelFormat: PixelFormat$1.LUMINANCE,
      sampler: new Sampler({
        wrapS: TextureWrap$1.CLAMP_TO_EDGE,
        wrapT: TextureWrap$1.CLAMP_TO_EDGE,
        minificationFilter: TextureMinificationFilter$1.LINEAR_MIPMAP_LINEAR,
        magnificationFilter: TextureMagnificationFilter$1.LINEAR,
      }),
    });

    cache.outlineTexture = texture;

    return texture;
  };

  function addOutline(
    model,
    meshId,
    primitiveId,
    edgeIndicesAccessorId,
    vertexNumberingScope
  ) {
    var vertexCopies = vertexNumberingScope.vertexCopies;
    var extraVertices = vertexNumberingScope.extraVertices;
    var outlineCoordinates = vertexNumberingScope.outlineCoordinates;

    var gltf = model.gltf;
    var mesh = gltf.meshes[meshId];
    var primitive = mesh.primitives[primitiveId];
    var accessors = gltf.accessors;
    var bufferViews = gltf.bufferViews;

    // Find the number of vertices in this primitive by looking at
    // the first attribute. Others are required to be the same.
    var numVertices;
    for (var semantic in primitive.attributes) {
      if (primitive.attributes.hasOwnProperty(semantic)) {
        var attributeId = primitive.attributes[semantic];
        var accessor = accessors[attributeId];
        if (defined(accessor)) {
          numVertices = accessor.count;
          break;
        }
      }
    }

    if (!defined(numVertices)) {
      return undefined;
    }

    var triangleIndexAccessorGltf = accessors[primitive.indices];
    var triangleIndexBufferViewGltf =
      bufferViews[triangleIndexAccessorGltf.bufferView];
    var edgeIndexAccessorGltf = accessors[edgeIndicesAccessorId];
    var edgeIndexBufferViewGltf = bufferViews[edgeIndexAccessorGltf.bufferView];

    var loadResources = model._loadResources;
    var triangleIndexBufferView = loadResources.getBuffer(
      triangleIndexBufferViewGltf
    );
    var edgeIndexBufferView = loadResources.getBuffer(edgeIndexBufferViewGltf);

    var triangleIndices =
      triangleIndexAccessorGltf.componentType === 5123
        ? new Uint16Array(
            triangleIndexBufferView.buffer,
            triangleIndexBufferView.byteOffset +
              triangleIndexAccessorGltf.byteOffset,
            triangleIndexAccessorGltf.count
          )
        : new Uint32Array(
            triangleIndexBufferView.buffer,
            triangleIndexBufferView.byteOffset +
              triangleIndexAccessorGltf.byteOffset,
            triangleIndexAccessorGltf.count
          );
    var edgeIndices =
      edgeIndexAccessorGltf.componentType === 5123
        ? new Uint16Array(
            edgeIndexBufferView.buffer,
            edgeIndexBufferView.byteOffset + edgeIndexAccessorGltf.byteOffset,
            edgeIndexAccessorGltf.count
          )
        : new Uint32Array(
            edgeIndexBufferView.buffer,
            edgeIndexBufferView.byteOffset + edgeIndexAccessorGltf.byteOffset,
            edgeIndexAccessorGltf.count
          );

    // Make a hash table for quick lookups of whether an edge exists between two
    // vertices. The hash is a sparse array indexed by
    //   `smallerVertexIndex * totalNumberOfVertices + biggerVertexIndex`
    // A value of 1 indicates an edge exists between the two vertex indices; any
    // other value indicates that it does not. We store the
    // `edgeSmallMultipler` - that is, the number of vertices in the equation
    // above - at index 0 for easy access to it later.

    var edgeSmallMultiplier = numVertices;

    var edges = [edgeSmallMultiplier];
    var i;
    for (i = 0; i < edgeIndices.length; i += 2) {
      var a = edgeIndices[i];
      var b = edgeIndices[i + 1];
      var small = Math.min(a, b);
      var big = Math.max(a, b);
      edges[small * edgeSmallMultiplier + big] = 1;
    }

    // For each triangle, adjust vertex data so that the correct edges are outlined.
    for (i = 0; i < triangleIndices.length; i += 3) {
      var i0 = triangleIndices[i];
      var i1 = triangleIndices[i + 1];
      var i2 = triangleIndices[i + 2];

      var all = false; // set this to true to draw a full wireframe.
      var has01 = all || isHighlighted(edges, i0, i1);
      var has12 = all || isHighlighted(edges, i1, i2);
      var has20 = all || isHighlighted(edges, i2, i0);

      var unmatchableVertexIndex = matchAndStoreCoordinates(
        outlineCoordinates,
        i0,
        i1,
        i2,
        has01,
        has12,
        has20
      );
      while (unmatchableVertexIndex >= 0) {
        // Copy the unmatchable index and try again.
        var copy;
        if (unmatchableVertexIndex === i0) {
          copy = vertexCopies[i0];
        } else if (unmatchableVertexIndex === i1) {
          copy = vertexCopies[i1];
        } else {
          copy = vertexCopies[i2];
        }

        if (copy === undefined) {
          copy = numVertices + extraVertices.length;

          var original = unmatchableVertexIndex;
          while (original >= numVertices) {
            original = extraVertices[original - numVertices];
          }
          extraVertices.push(original);
          vertexCopies[unmatchableVertexIndex] = copy;
        }

        if (
          copy > MAX_GLTF_UINT16_INDEX &&
          triangleIndices instanceof Uint16Array
        ) {
          // We outgrew a 16-bit index buffer, switch to 32-bit.
          triangleIndices = new Uint32Array(triangleIndices);
          triangleIndexAccessorGltf.componentType = 5125; // UNSIGNED_INT
          triangleIndexBufferViewGltf.buffer =
            gltf.buffers.push({
              byteLength: triangleIndices.byteLength,
              extras: {
                _pipeline: {
                  source: triangleIndices.buffer,
                },
              },
            }) - 1;
          triangleIndexBufferViewGltf.byteLength = triangleIndices.byteLength;
          triangleIndexBufferViewGltf.byteOffset = 0;
          model._loadResources.buffers[
            triangleIndexBufferViewGltf.buffer
          ] = new Uint8Array(
            triangleIndices.buffer,
            0,
            triangleIndices.byteLength
          );

          // The index componentType is also squirreled away in ModelLoadResources.
          // Hackily update it, or else we'll end up creating the wrong type
          // of index buffer later.
          loadResources.indexBuffersToCreate._array.forEach(function (toCreate) {
            if (toCreate.id === triangleIndexAccessorGltf.bufferView) {
              toCreate.componentType = triangleIndexAccessorGltf.componentType;
            }
          });
        }

        if (unmatchableVertexIndex === i0) {
          i0 = copy;
          triangleIndices[i] = copy;
        } else if (unmatchableVertexIndex === i1) {
          i1 = copy;
          triangleIndices[i + 1] = copy;
        } else {
          i2 = copy;
          triangleIndices[i + 2] = copy;
        }

        if (defined(triangleIndexAccessorGltf.max)) {
          triangleIndexAccessorGltf.max[0] = Math.max(
            triangleIndexAccessorGltf.max[0],
            copy
          );
        }

        unmatchableVertexIndex = matchAndStoreCoordinates(
          outlineCoordinates,
          i0,
          i1,
          i2,
          has01,
          has12,
          has20
        );
      }
    }
  }

  // Each vertex has three coordinates, a, b, and c.
  // a is the coordinate that applies to edge 2-0 for the vertex.
  // b is the coordinate that applies to edge 0-1 for the vertex.
  // c is the coordinate that applies to edge 1-2 for the vertex.

  // A single triangle with all edges highlighted:
  //
  //                 | a | b | c |
  //                 | 1 | 1 | 0 |
  //                       0
  //                      / \
  //                     /   \
  //           edge 0-1 /     \ edge 2-0
  //                   /       \
  //                  /         \
  // | a | b | c |   1-----------2   | a | b | c |
  // | 0 | 1 | 1 |     edge 1-2      | 1 | 0 | 1 |
  //
  // There are 6 possible orderings of coordinates a, b, and c:
  // 0 - abc
  // 1 - acb
  // 2 - bac
  // 3 - bca
  // 4 - cab
  // 5 - cba

  // All vertices must use the _same ordering_ for the edges to be rendered
  // correctly. So we compute a bitmask for each vertex, where the bit at
  // each position indicates whether that ordering works (i.e. doesn't
  // conflict with already-assigned coordinates) for that vertex.

  // Then we can find an ordering that works for all three vertices with a
  // bitwise AND.

  function computeOrderMask(outlineCoordinates, vertexIndex, a, b, c) {
    var startIndex = vertexIndex * 3;
    var first = outlineCoordinates[startIndex];
    var second = outlineCoordinates[startIndex + 1];
    var third = outlineCoordinates[startIndex + 2];

    if (first === undefined) {
      // If one coordinate is undefined, they all are, and all orderings are fine.
      return 63; // 0b111111;
    }

    return (
      ((first === a && second === b && third === c) << 0) +
      ((first === a && second === c && third === b) << 1) +
      ((first === b && second === a && third === c) << 2) +
      ((first === b && second === c && third === a) << 3) +
      ((first === c && second === a && third === b) << 4) +
      ((first === c && second === b && third === a) << 5)
    );
  }

  // popcount for integers 0-63, inclusive.
  // i.e. how many 1s are in the binary representation of the integer.
  function popcount0to63(value) {
    return (
      (value & 1) +
      ((value >> 1) & 1) +
      ((value >> 2) & 1) +
      ((value >> 3) & 1) +
      ((value >> 4) & 1) +
      ((value >> 5) & 1)
    );
  }

  function matchAndStoreCoordinates(
    outlineCoordinates,
    i0,
    i1,
    i2,
    has01,
    has12,
    has20
  ) {
    var a0 = has20 ? 1.0 : 0.0;
    var b0 = has01 ? 1.0 : 0.0;
    var c0 = 0.0;

    var i0Mask = computeOrderMask(outlineCoordinates, i0, a0, b0, c0);
    if (i0Mask === 0) {
      return i0;
    }

    var a1 = 0.0;
    var b1 = has01 ? 1.0 : 0.0;
    var c1 = has12 ? 1.0 : 0.0;

    var i1Mask = computeOrderMask(outlineCoordinates, i1, a1, b1, c1);
    if (i1Mask === 0) {
      return i1;
    }

    var a2 = has20 ? 1.0 : 0.0;
    var b2 = 0.0;
    var c2 = has12 ? 1.0 : 0.0;

    var i2Mask = computeOrderMask(outlineCoordinates, i2, a2, b2, c2);
    if (i2Mask === 0) {
      return i2;
    }

    var workingOrders = i0Mask & i1Mask & i2Mask;

    var a, b, c;

    if (workingOrders & (1 << 0)) {
      // 0 - abc
      a = 0;
      b = 1;
      c = 2;
    } else if (workingOrders & (1 << 1)) {
      // 1 - acb
      a = 0;
      c = 1;
      b = 2;
    } else if (workingOrders & (1 << 2)) {
      // 2 - bac
      b = 0;
      a = 1;
      c = 2;
    } else if (workingOrders & (1 << 3)) {
      // 3 - bca
      b = 0;
      c = 1;
      a = 2;
    } else if (workingOrders & (1 << 4)) {
      // 4 - cab
      c = 0;
      a = 1;
      b = 2;
    } else if (workingOrders & (1 << 5)) {
      // 5 - cba
      c = 0;
      b = 1;
      a = 2;
    } else {
      // No ordering works.
      // Report the most constrained vertex as unmatched so we copy that one.
      var i0Popcount = popcount0to63(i0Mask);
      var i1Popcount = popcount0to63(i1Mask);
      var i2Popcount = popcount0to63(i2Mask);
      if (i0Popcount < i1Popcount && i0Popcount < i2Popcount) {
        return i0;
      } else if (i1Popcount < i2Popcount) {
        return i1;
      }
      return i2;
    }

    var i0Start = i0 * 3;
    outlineCoordinates[i0Start + a] = a0;
    outlineCoordinates[i0Start + b] = b0;
    outlineCoordinates[i0Start + c] = c0;

    var i1Start = i1 * 3;
    outlineCoordinates[i1Start + a] = a1;
    outlineCoordinates[i1Start + b] = b1;
    outlineCoordinates[i1Start + c] = c1;

    var i2Start = i2 * 3;
    outlineCoordinates[i2Start + a] = a2;
    outlineCoordinates[i2Start + b] = b2;
    outlineCoordinates[i2Start + c] = c2;

    return -1;
  }

  function isHighlighted(edges, i0, i1) {
    var edgeSmallMultiplier = edges[0];
    var index = Math.min(i0, i1) * edgeSmallMultiplier + Math.max(i0, i1);

    // If i0 and i1 are both 0, then our index will be 0 and we'll end up
    // accessing the edgeSmallMultiplier that we've sneakily squirreled away
    // in index 0. But it makes no sense to have an edge between vertex 0 and
    // itself, so for any edgeSmallMultiplier other than 1 we'll return the
    // correct answer: false. If edgeSmallMultiplier is 1, that means there is
    // only a single vertex, so no danger of forming a meaningful triangle
    // with that.
    return edges[index] === 1;
  }

  function createTexture$2(size) {
    var texture = new Uint8Array(size);
    texture[size - 1] = 192;
    if (size === 8) {
      texture[size - 1] = 96;
    } else if (size === 4) {
      texture[size - 1] = 48;
    } else if (size === 2) {
      texture[size - 1] = 24;
    } else if (size === 1) {
      texture[size - 1] = 12;
    }
    return texture;
  }

  function updateBufferViewsWithNewVertices(model, bufferViews) {
    var gltf = model.gltf;
    var loadResources = model._loadResources;

    var i, j;
    for (i = 0; i < bufferViews.length; ++i) {
      var bufferView = bufferViews[i];
      var vertexNumberingScope = bufferView.extras._pipeline.vertexNumberingScope;

      // Let the temporary data be garbage collected.
      bufferView.extras._pipeline.vertexNumberingScope = undefined;

      var newVertices = vertexNumberingScope.extraVertices;

      var sourceData = loadResources.getBuffer(bufferView);
      var byteStride = bufferView.byteStride || 4;
      var newVerticesLength = newVertices.length;
      var destData = new Uint8Array(
        sourceData.byteLength + newVerticesLength * byteStride
      );

      // Copy the original vertices
      destData.set(sourceData);

      // Copy the vertices added for outlining
      for (j = 0; j < newVerticesLength; ++j) {
        var sourceIndex = newVertices[j] * byteStride;
        var destIndex = sourceData.length + j * byteStride;
        for (var k = 0; k < byteStride; ++k) {
          destData[destIndex + k] = destData[sourceIndex + k];
        }
      }

      // This bufferView is an independent buffer now. Update the model accordingly.
      bufferView.byteOffset = 0;
      bufferView.byteLength = destData.byteLength;

      var bufferId =
        gltf.buffers.push({
          byteLength: destData.byteLength,
          extras: {
            _pipeline: {
              source: destData.buffer,
            },
          },
        }) - 1;

      bufferView.buffer = bufferId;
      loadResources.buffers[bufferId] = destData;

      // Update the accessors to reflect the added vertices.
      var accessors = vertexNumberingScope.accessors;
      for (j = 0; j < accessors.length; ++j) {
        var accessorId = accessors[j];
        gltf.accessors[accessorId].count += newVerticesLength;
      }

      if (!vertexNumberingScope.createdOutlines) {
        // Create the buffers, views, and accessors for the outline texture coordinates.
        var outlineCoordinates = vertexNumberingScope.outlineCoordinates;
        var outlineCoordinateBuffer = new Float32Array(outlineCoordinates);
        var bufferIndex =
          model.gltf.buffers.push({
            byteLength: outlineCoordinateBuffer.byteLength,
            extras: {
              _pipeline: {
                source: outlineCoordinateBuffer.buffer,
              },
            },
          }) - 1;
        loadResources.buffers[bufferIndex] = new Uint8Array(
          outlineCoordinateBuffer.buffer,
          0,
          outlineCoordinateBuffer.byteLength
        );

        var bufferViewIndex =
          model.gltf.bufferViews.push({
            buffer: bufferIndex,
            byteLength: outlineCoordinateBuffer.byteLength,
            byteOffset: 0,
            byteStride: 3 * Float32Array.BYTES_PER_ELEMENT,
            target: 34962,
          }) - 1;

        var accessorIndex =
          model.gltf.accessors.push({
            bufferView: bufferViewIndex,
            byteOffset: 0,
            componentType: 5126,
            count: outlineCoordinateBuffer.length / 3,
            type: "VEC3",
            min: [0.0, 0.0, 0.0],
            max: [1.0, 1.0, 1.0],
          }) - 1;

        var primitives = vertexNumberingScope.primitives;
        for (j = 0; j < primitives.length; ++j) {
          primitives[j].attributes._OUTLINE_COORDINATES = accessorIndex;
        }

        loadResources.vertexBuffersToCreate.enqueue(bufferViewIndex);

        vertexNumberingScope.createdOutlines = true;
      }
    }
  }

  function compactBuffers(model) {
    var gltf = model.gltf;
    var loadResources = model._loadResources;

    var i;
    for (i = 0; i < gltf.buffers.length; ++i) {
      var buffer = gltf.buffers[i];
      var bufferViewsUsingThisBuffer = gltf.bufferViews.filter(
        usesBuffer.bind(undefined, i)
      );
      var newLength = bufferViewsUsingThisBuffer.reduce(function (
        previous,
        current
      ) {
        return previous + current.byteLength;
      },
      0);
      if (newLength === buffer.byteLength) {
        continue;
      }

      var newBuffer = new Uint8Array(newLength);
      var offset = 0;
      for (var j = 0; j < bufferViewsUsingThisBuffer.length; ++j) {
        var bufferView = bufferViewsUsingThisBuffer[j];
        var sourceData = loadResources.getBuffer(bufferView);
        newBuffer.set(sourceData, offset);

        bufferView.byteOffset = offset;
        offset += sourceData.byteLength;
      }

      loadResources.buffers[i] = newBuffer;
      buffer.extras._pipeline.source = newBuffer.buffer;
      buffer.byteLength = newLength;
    }
  }

  function usesBuffer(bufferId, bufferView) {
    return bufferView.buffer === bufferId;
  }

  function getVertexNumberingScope(model, primitive) {
    var attributes = primitive.attributes;
    if (attributes === undefined) {
      return undefined;
    }

    var gltf = model.gltf;

    var vertexNumberingScope;

    // Initialize common details for all bufferViews used by this primitive's vertices.
    // All bufferViews used by this primitive must use a common vertex numbering scheme.
    for (var semantic in attributes) {
      if (!attributes.hasOwnProperty(semantic)) {
        continue;
      }

      var accessorId = attributes[semantic];
      var accessor = gltf.accessors[accessorId];
      var bufferViewId = accessor.bufferView;
      var bufferView = gltf.bufferViews[bufferViewId];

      if (!defined(bufferView.extras)) {
        bufferView.extras = {};
      }
      if (!defined(bufferView.extras._pipeline)) {
        bufferView.extras._pipeline = {};
      }

      if (!defined(bufferView.extras._pipeline.vertexNumberingScope)) {
        bufferView.extras._pipeline.vertexNumberingScope = vertexNumberingScope || {
          // Each element in this array is:
          // a) undefined, if the vertex at this index has no copies
          // b) the index of the copy.
          vertexCopies: [],

          // Extra vertices appended after the ones originally included in the model.
          // Each element is the index of the vertex that this one is a copy of.
          extraVertices: [],

          // The texture coordinates used for outlining, three floats per vertex.
          outlineCoordinates: [],

          // The IDs of accessors that use this vertex numbering.
          accessors: [],

          // The IDs of bufferViews that use this vertex numbering.
          bufferViews: [],

          // The primitives that use this vertex numbering.
          primitives: [],

          // True if the buffer for the outlines has already been created.
          createdOutlines: false,
        };
      } else if (
        vertexNumberingScope !== undefined &&
        bufferView.extras._pipeline.vertexNumberingScope !== vertexNumberingScope
      ) {
        // Conflicting vertex numbering, let's give up.
        return undefined;
      }

      vertexNumberingScope = bufferView.extras._pipeline.vertexNumberingScope;

      if (vertexNumberingScope.bufferViews.indexOf(bufferView) < 0) {
        vertexNumberingScope.bufferViews.push(bufferView);
      }

      if (vertexNumberingScope.accessors.indexOf(accessorId) < 0) {
        vertexNumberingScope.accessors.push(accessorId);
      }
    }

    vertexNumberingScope.primitives.push(primitive);

    return vertexNumberingScope;
  }

  /**
   * Represents a command to the renderer for GPU Compute (using old-school GPGPU).
   *
   * @private
   * @constructor
   */
  function ComputeCommand(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The vertex array. If none is provided, a viewport quad will be used.
     *
     * @type {VertexArray}
     * @default undefined
     */
    this.vertexArray = options.vertexArray;

    /**
     * The fragment shader source. The default vertex shader is ViewportQuadVS.
     *
     * @type {ShaderSource}
     * @default undefined
     */
    this.fragmentShaderSource = options.fragmentShaderSource;

    /**
     * The shader program to apply.
     *
     * @type {ShaderProgram}
     * @default undefined
     */
    this.shaderProgram = options.shaderProgram;

    /**
     * An object with functions whose names match the uniforms in the shader program
     * and return values to set those uniforms.
     *
     * @type {Object}
     * @default undefined
     */
    this.uniformMap = options.uniformMap;

    /**
     * Texture to use for offscreen rendering.
     *
     * @type {Texture}
     * @default undefined
     */
    this.outputTexture = options.outputTexture;

    /**
     * Function that is called immediately before the ComputeCommand is executed. Used to
     * update any renderer resources. Takes the ComputeCommand as its single argument.
     *
     * @type {Function}
     * @default undefined
     */
    this.preExecute = options.preExecute;

    /**
     * Function that is called after the ComputeCommand is executed. Takes the output
     * texture as its single argument.
     *
     * @type {Function}
     * @default undefined
     */
    this.postExecute = options.postExecute;

    /**
     * Whether the renderer resources will persist beyond this call. If not, they
     * will be destroyed after completion.
     *
     * @type {Boolean}
     * @default false
     */
    this.persists = defaultValue(options.persists, false);

    /**
     * The pass when to render. Always compute pass.
     *
     * @type {Pass}
     * @default Pass.COMPUTE;
     */
    this.pass = Pass$1.COMPUTE;

    /**
     * The object who created this command.  This is useful for debugging command
     * execution; it allows us to see who created a command when we only have a
     * reference to the command, and can be used to selectively execute commands
     * with {@link Scene#debugCommandFilter}.
     *
     * @type {Object}
     * @default undefined
     *
     * @see Scene#debugCommandFilter
     */
    this.owner = options.owner;
  }

  /**
   * Executes the compute command.
   *
   * @param {ComputeEngine} computeEngine The context that processes the compute command.
   */
  ComputeCommand.prototype.execute = function (computeEngine) {
    computeEngine.execute(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var OctahedralProjectionAtlasFS = "varying vec2 v_textureCoordinates;\n\
uniform float originalSize;\n\
uniform sampler2D texture0;\n\
uniform sampler2D texture1;\n\
uniform sampler2D texture2;\n\
uniform sampler2D texture3;\n\
uniform sampler2D texture4;\n\
uniform sampler2D texture5;\n\
const float yMipLevel1 = 1.0 - (1.0 / pow(2.0, 1.0));\n\
const float yMipLevel2 = 1.0 - (1.0 / pow(2.0, 2.0));\n\
const float yMipLevel3 = 1.0 - (1.0 / pow(2.0, 3.0));\n\
const float yMipLevel4 = 1.0 - (1.0 / pow(2.0, 4.0));\n\
void main()\n\
{\n\
vec2 uv = v_textureCoordinates;\n\
vec2 textureSize = vec2(originalSize * 1.5 + 2.0, originalSize);\n\
vec2 pixel = 1.0 / textureSize;\n\
float mipLevel = 0.0;\n\
if (uv.x - pixel.x > (textureSize.y / textureSize.x))\n\
{\n\
mipLevel = 1.0;\n\
if (uv.y - pixel.y > yMipLevel1)\n\
{\n\
mipLevel = 2.0;\n\
if (uv.y - pixel.y * 3.0 > yMipLevel2)\n\
{\n\
mipLevel = 3.0;\n\
if (uv.y - pixel.y * 5.0 > yMipLevel3)\n\
{\n\
mipLevel = 4.0;\n\
if (uv.y - pixel.y * 7.0 > yMipLevel4)\n\
{\n\
mipLevel = 5.0;\n\
}\n\
}\n\
}\n\
}\n\
}\n\
if (mipLevel > 0.0)\n\
{\n\
float scale = pow(2.0, mipLevel);\n\
uv.y -= (pixel.y * (mipLevel - 1.0) * 2.0);\n\
uv.x *= ((textureSize.x - 2.0) / textureSize.y);\n\
uv.x -= 1.0 + pixel.x;\n\
uv.y -= (1.0 - (1.0 / pow(2.0, mipLevel - 1.0)));\n\
uv *= scale;\n\
}\n\
else\n\
{\n\
uv.x *= (textureSize.x / textureSize.y);\n\
}\n\
if(mipLevel == 0.0)\n\
{\n\
gl_FragColor = texture2D(texture0, uv);\n\
}\n\
else if(mipLevel == 1.0)\n\
{\n\
gl_FragColor = texture2D(texture1, uv);\n\
}\n\
else if(mipLevel == 2.0)\n\
{\n\
gl_FragColor = texture2D(texture2, uv);\n\
}\n\
else if(mipLevel == 3.0)\n\
{\n\
gl_FragColor = texture2D(texture3, uv);\n\
}\n\
else if(mipLevel == 4.0)\n\
{\n\
gl_FragColor = texture2D(texture4, uv);\n\
}\n\
else if(mipLevel == 5.0)\n\
{\n\
gl_FragColor = texture2D(texture5, uv);\n\
}\n\
else\n\
{\n\
gl_FragColor = vec4(0.0);\n\
}\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var OctahedralProjectionFS = "varying vec3 v_cubeMapCoordinates;\n\
uniform samplerCube cubeMap;\n\
void main()\n\
{\n\
vec4 rgbm = textureCube(cubeMap, v_cubeMapCoordinates);\n\
float m = rgbm.a * 16.0;\n\
vec3 r = rgbm.rgb * m;\n\
gl_FragColor = vec4(r * r, 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var OctahedralProjectionVS = "attribute vec4 position;\n\
attribute vec3 cubeMapCoordinates;\n\
varying vec3 v_cubeMapCoordinates;\n\
void main()\n\
{\n\
gl_Position = position;\n\
v_cubeMapCoordinates = cubeMapCoordinates;\n\
}\n\
";

  /**
   * Packs all mip levels of a cube map into a 2D texture atlas.
   *
   * Octahedral projection is a way of putting the cube maps onto a 2D texture
   * with minimal distortion and easy look up.
   * See Chapter 16 of WebGL Insights "HDR Image-Based Lighting on the Web" by Jeff Russell
   * and "Octahedron Environment Maps" for reference.
   *
   * @private
   */
  function OctahedralProjectedCubeMap(url) {
    this._url = url;

    this._cubeMapBuffers = undefined;
    this._cubeMaps = undefined;
    this._texture = undefined;
    this._mipTextures = undefined;
    this._va = undefined;
    this._sp = undefined;

    this._maximumMipmapLevel = undefined;

    this._loading = false;
    this._ready = false;
    this._readyPromise = when.defer();
  }

  Object.defineProperties(OctahedralProjectedCubeMap.prototype, {
    /**
     * The url to the KTX file containing the specular environment map and convoluted mipmaps.
     * @memberof OctahedralProjectedCubeMap.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._url;
      },
    },
    /**
     * A texture containing all the packed convolutions.
     * @memberof OctahedralProjectedCubeMap.prototype
     * @type {Texture}
     * @readonly
     */
    texture: {
      get: function () {
        return this._texture;
      },
    },
    /**
     * The maximum number of mip levels.
     * @memberOf OctahedralProjectedCubeMap.prototype
     * @type {Number}
     * @readonly
     */
    maximumMipmapLevel: {
      get: function () {
        return this._maximumMipmapLevel;
      },
    },
    /**
     * Determines if the texture atlas is complete and ready to use.
     * @memberof OctahedralProjectedCubeMap.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },
    /**
     * Gets a promise that resolves when the texture atlas is ready to use.
     * @memberof OctahedralProjectedCubeMap.prototype
     * @type {Promise<void>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  OctahedralProjectedCubeMap.isSupported = function (context) {
    return (
      (context.colorBufferHalfFloat && context.halfFloatingPointTexture) ||
      (context.floatingPointTexture && context.colorBufferFloat)
    );
  };

  // These vertices are based on figure 1 from "Octahedron Environment Maps".
  var v1$1 = new Cartesian3(1.0, 0.0, 0.0);
  var v2$1 = new Cartesian3(0.0, 0.0, 1.0);
  var v3 = new Cartesian3(-1.0, 0.0, 0.0);
  var v4 = new Cartesian3(0.0, 0.0, -1.0);
  var v5 = new Cartesian3(0.0, 1.0, 0.0);
  var v6 = new Cartesian3(0.0, -1.0, 0.0);

  // top left, left, top, center, right, top right, bottom, bottom left, bottom right
  var cubeMapCoordinates = [v5, v3, v2$1, v6, v1$1, v5, v4, v5, v5];
  var length$1 = cubeMapCoordinates.length;
  var flatCubeMapCoordinates = new Float32Array(length$1 * 3);

  var offset = 0;
  for (var i$2 = 0; i$2 < length$1; ++i$2, offset += 3) {
    Cartesian3.pack(cubeMapCoordinates[i$2], flatCubeMapCoordinates, offset);
  }

  var flatPositions = new Float32Array([
    -1.0,
    1.0, // top left
    -1.0,
    0.0, // left
    0.0,
    1.0, // top
    0.0,
    0.0, // center
    1.0,
    0.0, // right
    1.0,
    1.0, // top right
    0.0,
    -1.0, // bottom
    -1.0,
    -1.0, // bottom left
    1.0,
    -1.0, // bottom right
  ]);
  var indices = new Uint16Array([
    0,
    1,
    2, // top left, left, top,
    2,
    3,
    1, // top, center, left,
    7,
    6,
    1, // bottom left, bottom, left,
    3,
    6,
    1, // center, bottom, left,
    2,
    5,
    4, // top, top right, right,
    3,
    4,
    2, // center, right, top,
    4,
    8,
    6, // right, bottom right, bottom,
    3,
    4,
    6, //center, right, bottom
  ]);

  function createVertexArray$3(context) {
    var positionBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: flatPositions,
      usage: BufferUsage$1.STATIC_DRAW,
    });
    var cubeMapCoordinatesBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: flatCubeMapCoordinates,
      usage: BufferUsage$1.STATIC_DRAW,
    });
    var indexBuffer = Buffer$1.createIndexBuffer({
      context: context,
      typedArray: indices,
      usage: BufferUsage$1.STATIC_DRAW,
      indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
    });

    var attributes = [
      {
        index: 0,
        vertexBuffer: positionBuffer,
        componentsPerAttribute: 2,
        componentDatatype: ComponentDatatype$1.FLOAT,
      },
      {
        index: 1,
        vertexBuffer: cubeMapCoordinatesBuffer,
        componentsPerAttribute: 3,
        componentDatatype: ComponentDatatype$1.FLOAT,
      },
    ];
    return new VertexArray({
      context: context,
      attributes: attributes,
      indexBuffer: indexBuffer,
    });
  }

  function createUniformTexture(texture) {
    return function () {
      return texture;
    };
  }

  function cleanupResources(map) {
    map._va = map._va && map._va.destroy();
    map._sp = map._sp && map._sp.destroy();

    var i;
    var length;

    var cubeMaps = map._cubeMaps;
    if (defined(cubeMaps)) {
      length = cubeMaps.length;
      for (i = 0; i < length; ++i) {
        cubeMaps[i].destroy();
      }
    }
    var mipTextures = map._mipTextures;
    if (defined(mipTextures)) {
      length = mipTextures.length;
      for (i = 0; i < length; ++i) {
        mipTextures[i].destroy();
      }
    }

    map._va = undefined;
    map._sp = undefined;
    map._cubeMaps = undefined;
    map._cubeMapBuffers = undefined;
    map._mipTextures = undefined;
  }

  /**
   * Creates compute commands to generate octahedral projections of each cube map
   * and then renders them to an atlas.
   * <p>
   * Only needs to be called twice. The first call queues the compute commands to generate the atlas.
   * The second call cleans up unused resources. Every call afterwards is a no-op.
   * </p>
   *
   * @param {FrameState} frameState The frame state.
   *
   * @private
   */
  OctahedralProjectedCubeMap.prototype.update = function (frameState) {
    var context = frameState.context;

    if (!OctahedralProjectedCubeMap.isSupported(context)) {
      return;
    }

    if (defined(this._texture) && defined(this._va)) {
      cleanupResources(this);
    }
    if (defined(this._texture)) {
      return;
    }

    if (!defined(this._texture) && !this._loading) {
      var cachedTexture = context.textureCache.getTexture(this._url);
      if (defined(cachedTexture)) {
        cleanupResources(this);
        this._texture = cachedTexture;
        this._maximumMipmapLevel = this._texture.maximumMipmapLevel;
        this._ready = true;
        this._readyPromise.resolve();
        return;
      }
    }

    var cubeMapBuffers = this._cubeMapBuffers;
    if (!defined(cubeMapBuffers) && !this._loading) {
      var that = this;
      loadKTX(this._url)
        .then(function (buffers) {
          that._cubeMapBuffers = buffers;
          that._loading = false;
        })
        .otherwise(this._readyPromise.reject);
      this._loading = true;
    }
    if (!defined(this._cubeMapBuffers)) {
      return;
    }

    this._va = createVertexArray$3(context);
    this._sp = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: OctahedralProjectionVS,
      fragmentShaderSource: OctahedralProjectionFS,
      attributeLocations: {
        position: 0,
        cubeMapCoordinates: 1,
      },
    });

    // We only need up to 6 mip levels to avoid artifacts.
    var length = Math.min(cubeMapBuffers.length, 6);
    this._maximumMipmapLevel = length - 1;
    var cubeMaps = (this._cubeMaps = new Array(length));
    var mipTextures = (this._mipTextures = new Array(length));
    var originalSize = cubeMapBuffers[0].positiveX.width * 2.0;
    var uniformMap = {
      originalSize: function () {
        return originalSize;
      },
    };

    var pixelDatatype = context.halfFloatingPointTexture
      ? PixelDatatype$1.HALF_FLOAT
      : PixelDatatype$1.FLOAT;
    var pixelFormat = PixelFormat$1.RGBA;

    // First we project each cubemap onto a flat octahedron, and write that to a texture.
    for (var i = 0; i < length; ++i) {
      // Swap +Y/-Y faces since the octahedral projection expects this order.
      var positiveY = cubeMapBuffers[i].positiveY;
      cubeMapBuffers[i].positiveY = cubeMapBuffers[i].negativeY;
      cubeMapBuffers[i].negativeY = positiveY;

      var cubeMap = (cubeMaps[i] = new CubeMap({
        context: context,
        source: cubeMapBuffers[i],
      }));
      var size = cubeMaps[i].width * 2;

      var mipTexture = (mipTextures[i] = new Texture({
        context: context,
        width: size,
        height: size,
        pixelDatatype: pixelDatatype,
        pixelFormat: pixelFormat,
      }));

      var command = new ComputeCommand({
        vertexArray: this._va,
        shaderProgram: this._sp,
        uniformMap: {
          cubeMap: createUniformTexture(cubeMap),
        },
        outputTexture: mipTexture,
        persists: true,
        owner: this,
      });
      frameState.commandList.push(command);

      uniformMap["texture" + i] = createUniformTexture(mipTexture);
    }

    this._texture = new Texture({
      context: context,
      width: originalSize * 1.5 + 2.0, // We add a 1 pixel border to avoid linear sampling artifacts.
      height: originalSize,
      pixelDatatype: pixelDatatype,
      pixelFormat: pixelFormat,
    });

    this._texture.maximumMipmapLevel = this._maximumMipmapLevel;
    context.textureCache.addTexture(this._url, this._texture);

    var atlasCommand = new ComputeCommand({
      fragmentShaderSource: OctahedralProjectionAtlasFS,
      uniformMap: uniformMap,
      outputTexture: this._texture,
      persists: false,
      owner: this,
    });
    frameState.commandList.push(atlasCommand);

    this._ready = true;
    this._readyPromise.resolve();
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see OctahedralProjectedCubeMap#destroy
   */
  OctahedralProjectedCubeMap.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see OctahedralProjectedCubeMap#isDestroyed
   */
  OctahedralProjectedCubeMap.prototype.destroy = function () {
    cleanupResources(this);
    this._texture = this._texture && this._texture.destroy();
    return destroyObject(this);
  };

  var boundingSphereCartesian3Scratch$1 = new Cartesian3();

  var ModelState$1 = ModelUtility.ModelState;

  // glTF MIME types discussed in https://github.com/KhronosGroup/glTF/issues/412 and https://github.com/KhronosGroup/glTF/issues/943
  var defaultModelAccept =
    "model/gltf-binary,model/gltf+json;q=0.8,application/json;q=0.2,*/*;q=0.01";

  var articulationEpsilon = CesiumMath.EPSILON16;

  ///////////////////////////////////////////////////////////////////////////

  function setCachedGltf(model, cachedGltf) {
    model._cachedGltf = cachedGltf;
  }

  // glTF JSON can be big given embedded geometry, textures, and animations, so we
  // cache it across all models using the same url/cache-key.  This also reduces the
  // slight overhead in assigning defaults to missing values.
  //
  // Note that this is a global cache, compared to renderer resources, which
  // are cached per context.
  function CachedGltf(options) {
    this._gltf = options.gltf;
    this.ready = options.ready;
    this.modelsToLoad = [];
    this.count = 0;
  }

  Object.defineProperties(CachedGltf.prototype, {
    gltf: {
      set: function (value) {
        this._gltf = value;
      },

      get: function () {
        return this._gltf;
      },
    },
  });

  CachedGltf.prototype.makeReady = function (gltfJson) {
    this.gltf = gltfJson;

    var models = this.modelsToLoad;
    var length = models.length;
    for (var i = 0; i < length; ++i) {
      var m = models[i];
      if (!m.isDestroyed()) {
        setCachedGltf(m, this);
      }
    }
    this.modelsToLoad = undefined;
    this.ready = true;
  };

  var gltfCache = {};
  var uriToGuid = {};
  ///////////////////////////////////////////////////////////////////////////

  /**
   * A 3D model based on glTF, the runtime asset format for WebGL, OpenGL ES, and OpenGL.
   * <p>
   * Cesium includes support for geometry and materials, glTF animations, and glTF skinning.
   * In addition, individual glTF nodes are pickable with {@link Scene#pick} and animatable
   * with {@link Model#getNode}.  glTF cameras and lights are not currently supported.
   * </p>
   * <p>
   * An external glTF asset is created with {@link Model.fromGltf}.  glTF JSON can also be
   * created at runtime and passed to this constructor function.  In either case, the
   * {@link Model#readyPromise} is resolved when the model is ready to render, i.e.,
   * when the external binary, image, and shader files are downloaded and the WebGL
   * resources are created.
   * </p>
   * <p>
   * Cesium supports glTF assets with the following extensions:
   * <ul>
   * <li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Khronos/KHR_binary_glTF/README.md|KHR_binary_glTF (glTF 1.0)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Khronos/KHR_materials_common/README.md|KHR_materials_common (glTF 1.0)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Vendor/WEB3D_quantized_attributes/README.md|WEB3D_quantized_attributes (glTF 1.0)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/AGI_articulations/README.md|AGI_articulations}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/pull/1302|KHR_blend (draft)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_draco_mesh_compression/README.md|KHR_draco_mesh_compression}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness/README.md|KHR_materials_pbrSpecularGlossiness}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit/README.md|KHR_materials_unlit}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_techniques_webgl/README.md|KHR_techniques_webgl}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_texture_transform/README.md|KHR_texture_transform}
   * </li>
   * </ul>
   * </p>
   * <p>
   * For high-precision rendering, Cesium supports the {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Vendor/CESIUM_RTC/README.md|CESIUM_RTC} extension, which introduces the
   * CESIUM_RTC_MODELVIEW parameter semantic that says the node is in WGS84 coordinates translated
   * relative to a local origin.
   * </p>
   *
   * @alias Model
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Object|ArrayBuffer|Uint8Array} [options.gltf] A glTF JSON object, or a binary glTF buffer.
   * @param {Resource|String} [options.basePath=''] The base path that paths in the glTF JSON are relative to.
   * @param {Boolean} [options.show=true] Determines if the model primitive will be shown.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the model from model to world coordinates.
   * @param {Number} [options.scale=1.0] A uniform scale applied to this model.
   * @param {Number} [options.minimumPixelSize=0.0] The approximate minimum pixel size of the model regardless of zoom.
   * @param {Number} [options.maximumScale] The maximum scale size of a model. An upper limit for minimumPixelSize.
   * @param {Object} [options.id] A user-defined object to return when the model is picked with {@link Scene#pick}.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each glTF mesh and primitive is pickable with {@link Scene#pick}.
   * @param {Boolean} [options.incrementallyLoadTextures=true] Determine if textures may continue to stream in after the model is loaded.
   * @param {Boolean} [options.asynchronous=true] Determines if model WebGL resource creation will be spread out over several frames or block until completion once all glTF files are loaded.
   * @param {Boolean} [options.clampAnimations=true] Determines if the model's animations should hold a pose over frames where no keyframes are specified.
   * @param {ShadowMode} [options.shadows=ShadowMode.ENABLED] Determines whether the model casts or receives shadows from light sources.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Draws the bounding sphere for each draw command in the model.
   * @param {Boolean} [options.debugWireframe=false] For debugging only. Draws the model in wireframe.
   * @param {HeightReference} [options.heightReference=HeightReference.NONE] Determines how the model is drawn relative to terrain.
   * @param {Scene} [options.scene] Must be passed in for models that use the height reference property.
   * @param {DistanceDisplayCondition} [options.distanceDisplayCondition] The condition specifying at what distance from the camera that this model will be displayed.
   * @param {Color} [options.color=Color.WHITE] A color that blends with the model's rendered color.
   * @param {ColorBlendMode} [options.colorBlendMode=ColorBlendMode.HIGHLIGHT] Defines how the color blends with the model.
   * @param {Number} [options.colorBlendAmount=0.5] Value used to determine the color strength when the <code>colorBlendMode</code> is <code>MIX</code>. A value of 0.0 results in the model's rendered color while a value of 1.0 results in a solid color, with any value in-between resulting in a mix of the two.
   * @param {Color} [options.silhouetteColor=Color.RED] The silhouette color. If more than 256 models have silhouettes enabled, there is a small chance that overlapping models will have minor artifacts.
   * @param {Number} [options.silhouetteSize=0.0] The size of the silhouette in pixels.
   * @param {ClippingPlaneCollection} [options.clippingPlanes] The {@link ClippingPlaneCollection} used to selectively disable rendering the model.
   * @param {Boolean} [options.dequantizeInShader=true] Determines if a {@link https://github.com/google/draco|Draco} encoded model is dequantized on the GPU. This decreases total memory usage for encoded models.
   * @param {Cartesian2} [options.imageBasedLightingFactor=Cartesian2(1.0, 1.0)] Scales diffuse and specular image-based lighting from the earth, sky, atmosphere and star skybox.
   * @param {Cartesian3} [options.lightColor] The light color when shading the model. When <code>undefined</code> the scene's light color is used instead.
   * @param {Number} [options.luminanceAtZenith=0.2] The sun's luminance at the zenith in kilo candela per meter squared to use for this model's procedural environment map.
   * @param {Cartesian3[]} [options.sphericalHarmonicCoefficients] The third order spherical harmonic coefficients used for the diffuse color of image-based lighting.
   * @param {String} [options.specularEnvironmentMaps] A URL to a KTX file that contains a cube map of the specular lighting and the convoluted specular mipmaps.
   * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
   * @param {Boolean} [options.backFaceCulling=true] Whether to cull back-facing geometry. When true, back face culling is determined by the material's doubleSided property; when false, back face culling is disabled. Back faces are not culled if {@link Model#color} is translucent or {@link Model#silhouetteSize} is greater than 0.0.
   *
   * @see Model.fromGltf
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=3D%20Models.html|Cesium Sandcastle Models Demo}
   */
  function Model(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var cacheKey = options.cacheKey;
    this._cacheKey = cacheKey;
    this._cachedGltf = undefined;
    this._releaseGltfJson = defaultValue(options.releaseGltfJson, false);

    var cachedGltf;
    if (
      defined(cacheKey) &&
      defined(gltfCache[cacheKey]) &&
      gltfCache[cacheKey].ready
    ) {
      // glTF JSON is in cache and ready
      cachedGltf = gltfCache[cacheKey];
      ++cachedGltf.count;
    } else {
      // glTF was explicitly provided, e.g., when a user uses the Model constructor directly
      var gltf = options.gltf;

      if (defined(gltf)) {
        if (gltf instanceof ArrayBuffer) {
          gltf = new Uint8Array(gltf);
        }

        if (gltf instanceof Uint8Array) {
          // Binary glTF
          var parsedGltf = parseGlb(gltf);

          cachedGltf = new CachedGltf({
            gltf: parsedGltf,
            ready: true,
          });
        } else {
          // Normal glTF (JSON)
          cachedGltf = new CachedGltf({
            gltf: options.gltf,
            ready: true,
          });
        }

        cachedGltf.count = 1;

        if (defined(cacheKey)) {
          gltfCache[cacheKey] = cachedGltf;
        }
      }
    }
    setCachedGltf(this, cachedGltf);

    var basePath = defaultValue(options.basePath, "");
    this._resource = Resource.createIfNeeded(basePath);

    // User specified credit
    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    // Create a list of Credit's so they can be added from the Resource later
    this._resourceCredits = [];

    /**
     * Determines if the model primitive will be shown.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * The silhouette color.
     *
     * @type {Color}
     *
     * @default Color.RED
     */
    this.silhouetteColor = defaultValue(options.silhouetteColor, Color.RED);
    this._silhouetteColor = new Color();
    this._silhouetteColorPreviousAlpha = 1.0;
    this._normalAttributeName = undefined;

    /**
     * The size of the silhouette in pixels.
     *
     * @type {Number}
     *
     * @default 0.0
     */
    this.silhouetteSize = defaultValue(options.silhouetteSize, 0.0);

    /**
     * The 4x4 transformation matrix that transforms the model from model to world coordinates.
     * When this is the identity matrix, the model is drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type {Matrix4}
     *
     * @default {@link Matrix4.IDENTITY}
     *
     * @example
     * var origin = Cesium.Cartesian3.fromDegrees(-95.0, 40.0, 200000.0);
     * m.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = Matrix4.clone(this.modelMatrix);
    this._clampedModelMatrix = undefined;

    /**
     * A uniform scale applied to this model before the {@link Model#modelMatrix}.
     * Values greater than <code>1.0</code> increase the size of the model; values
     * less than <code>1.0</code> decrease.
     *
     * @type {Number}
     *
     * @default 1.0
     */
    this.scale = defaultValue(options.scale, 1.0);
    this._scale = this.scale;

    /**
     * The approximate minimum pixel size of the model regardless of zoom.
     * This can be used to ensure that a model is visible even when the viewer
     * zooms out.  When <code>0.0</code>, no minimum size is enforced.
     *
     * @type {Number}
     *
     * @default 0.0
     */
    this.minimumPixelSize = defaultValue(options.minimumPixelSize, 0.0);
    this._minimumPixelSize = this.minimumPixelSize;

    /**
     * The maximum scale size for a model. This can be used to give
     * an upper limit to the {@link Model#minimumPixelSize}, ensuring that the model
     * is never an unreasonable scale.
     *
     * @type {Number}
     */
    this.maximumScale = options.maximumScale;
    this._maximumScale = this.maximumScale;

    /**
     * User-defined object returned when the model is picked.
     *
     * @type Object
     *
     * @default undefined
     *
     * @see Scene#pick
     */
    this.id = options.id;
    this._id = options.id;

    /**
     * Returns the height reference of the model
     *
     * @type {HeightReference}
     *
     * @default HeightReference.NONE
     */
    this.heightReference = defaultValue(
      options.heightReference,
      HeightReference$1.NONE
    );
    this._heightReference = this.heightReference;
    this._heightChanged = false;
    this._removeUpdateHeightCallback = undefined;
    var scene = options.scene;
    this._scene = scene;
    if (defined(scene) && defined(scene.terrainProviderChanged)) {
      this._terrainProviderChangedCallback = scene.terrainProviderChanged.addEventListener(
        function () {
          this._heightChanged = true;
        },
        this
      );
    }

    /**
     * Used for picking primitives that wrap a model.
     *
     * @private
     */
    this._pickObject = options.pickObject;
    this._allowPicking = defaultValue(options.allowPicking, true);

    this._ready = false;
    this._readyPromise = when.defer();

    /**
     * The currently playing glTF animations.
     *
     * @type {ModelAnimationCollection}
     */
    this.activeAnimations = new ModelAnimationCollection(this);

    /**
     * Determines if the model's animations should hold a pose over frames where no keyframes are specified.
     *
     * @type {Boolean}
     */
    this.clampAnimations = defaultValue(options.clampAnimations, true);

    this._defaultTexture = undefined;
    this._incrementallyLoadTextures = defaultValue(
      options.incrementallyLoadTextures,
      true
    );
    this._asynchronous = defaultValue(options.asynchronous, true);

    /**
     * Determines whether the model casts or receives shadows from light sources.
     *
     * @type {ShadowMode}
     *
     * @default ShadowMode.ENABLED
     */
    this.shadows = defaultValue(options.shadows, ShadowMode$1.ENABLED);
    this._shadows = this.shadows;

    /**
     * A color that blends with the model's rendered color.
     *
     * @type {Color}
     *
     * @default Color.WHITE
     */
    this.color = Color.clone(defaultValue(options.color, Color.WHITE));
    this._colorPreviousAlpha = 1.0;

    /**
     * Defines how the color blends with the model.
     *
     * @type {ColorBlendMode}
     *
     * @default ColorBlendMode.HIGHLIGHT
     */
    this.colorBlendMode = defaultValue(
      options.colorBlendMode,
      ColorBlendMode$1.HIGHLIGHT
    );

    /**
     * Value used to determine the color strength when the <code>colorBlendMode</code> is <code>MIX</code>.
     * A value of 0.0 results in the model's rendered color while a value of 1.0 results in a solid color, with
     * any value in-between resulting in a mix of the two.
     *
     * @type {Number}
     *
     * @default 0.5
     */
    this.colorBlendAmount = defaultValue(options.colorBlendAmount, 0.5);

    this._colorShadingEnabled = false;

    this._clippingPlanes = undefined;
    this.clippingPlanes = options.clippingPlanes;
    // Used for checking if shaders need to be regenerated due to clipping plane changes.
    this._clippingPlanesState = 0;
    // If defined, use this matrix to position the clipping planes instead of the modelMatrix.
    // This is so that when models are part of a tileset they all get clipped relative
    // to the root tile.
    this.clippingPlanesOriginMatrix = undefined;

    /**
     * Whether to cull back-facing geometry. When true, back face culling is
     * determined by the material's doubleSided property; when false, back face
     * culling is disabled. Back faces are not culled if {@link Model#color} is
     * translucent or {@link Model#silhouetteSize} is greater than 0.0.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.backFaceCulling = defaultValue(options.backFaceCulling, true);

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the model.  A glTF primitive corresponds
     * to one draw command.  A glTF mesh has an array of primitives, often of length one.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );
    this._debugShowBoundingVolume = false;

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the model in wireframe.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugWireframe = defaultValue(options.debugWireframe, false);
    this._debugWireframe = false;

    this._distanceDisplayCondition = options.distanceDisplayCondition;

    // Undocumented options
    this._addBatchIdToGeneratedShaders = options.addBatchIdToGeneratedShaders;
    this._precreatedAttributes = options.precreatedAttributes;
    this._vertexShaderLoaded = options.vertexShaderLoaded;
    this._fragmentShaderLoaded = options.fragmentShaderLoaded;
    this._uniformMapLoaded = options.uniformMapLoaded;
    this._pickIdLoaded = options.pickIdLoaded;
    this._ignoreCommands = defaultValue(options.ignoreCommands, false);
    this._requestType = options.requestType;
    this._upAxis = defaultValue(options.upAxis, Axis$1.Y);
    this._gltfForwardAxis = Axis$1.Z;
    this._forwardAxis = options.forwardAxis;

    /**
     * @private
     * @readonly
     */
    this.cull = defaultValue(options.cull, true);

    /**
     * @private
     * @readonly
     */
    this.opaquePass = defaultValue(options.opaquePass, Pass$1.OPAQUE);

    this._computedModelMatrix = new Matrix4(); // Derived from modelMatrix and scale
    this._clippingPlaneModelViewMatrix = Matrix4.clone(Matrix4.IDENTITY); // Derived from modelMatrix, scale, and the current view matrix
    this._initialRadius = undefined; // Radius without model's scale property, model-matrix scale, animations, or skins
    this._boundingSphere = undefined;
    this._scaledBoundingSphere = new BoundingSphere();
    this._state = ModelState$1.NEEDS_LOAD;
    this._loadResources = undefined;

    this._mode = undefined;

    this._perNodeShowDirty = false; // true when the Cesium API was used to change a node's show property
    this._cesiumAnimationsDirty = false; // true when the Cesium API, not a glTF animation, changed a node transform
    this._dirty = false; // true when the model was transformed this frame
    this._maxDirtyNumber = 0; // Used in place of a dirty boolean flag to avoid an extra graph traversal

    this._runtime = {
      animations: undefined,
      articulationsByName: undefined,
      articulationsByStageKey: undefined,
      stagesByKey: undefined,
      rootNodes: undefined,
      nodes: undefined, // Indexed with the node's index
      nodesByName: undefined, // Indexed with name property in the node
      skinnedNodes: undefined,
      meshesByName: undefined, // Indexed with the name property in the mesh
      materialsByName: undefined, // Indexed with the name property in the material
      materialsById: undefined, // Indexed with the material's index
    };

    this._uniformMaps = {}; // Not cached since it can be targeted by glTF animation
    this._extensionsUsed = undefined; // Cached used glTF extensions
    this._extensionsRequired = undefined; // Cached required glTF extensions
    this._quantizedUniforms = {}; // Quantized uniforms for each program for WEB3D_quantized_attributes
    this._programPrimitives = {};
    this._rendererResources = {
      // Cached between models with the same url/cache-key
      buffers: {},
      vertexArrays: {},
      programs: {},
      sourceShaders: {},
      silhouettePrograms: {},
      textures: {},
      samplers: {},
      renderStates: {},
    };
    this._cachedRendererResources = undefined;
    this._loadRendererResourcesFromCache = false;

    this._dequantizeInShader = defaultValue(options.dequantizeInShader, true);
    this._decodedData = {};

    this._cachedGeometryByteLength = 0;
    this._cachedTexturesByteLength = 0;
    this._geometryByteLength = 0;
    this._texturesByteLength = 0;
    this._trianglesLength = 0;

    // Hold references for shader reconstruction.
    // Hold these separately because _cachedGltf may get released (this.releaseGltfJson)
    this._sourceTechniques = {};
    this._sourcePrograms = {};
    this._quantizedVertexShaders = {};

    this._nodeCommands = [];
    this._pickIds = [];

    // CESIUM_RTC extension
    this._rtcCenter = undefined; // reference to either 3D or 2D
    this._rtcCenterEye = undefined; // in eye coordinates
    this._rtcCenter3D = undefined; // in world coordinates
    this._rtcCenter2D = undefined; // in projected world coordinates

    this._sourceVersion = undefined;
    this._sourceKHRTechniquesWebGL = undefined;

    this._imageBasedLightingFactor = new Cartesian2(1.0, 1.0);
    Cartesian2.clone(
      options.imageBasedLightingFactor,
      this._imageBasedLightingFactor
    );
    this._lightColor = Cartesian3.clone(options.lightColor);

    this._luminanceAtZenith = undefined;
    this.luminanceAtZenith = defaultValue(options.luminanceAtZenith, 0.2);

    this._sphericalHarmonicCoefficients = options.sphericalHarmonicCoefficients;
    this._specularEnvironmentMaps = options.specularEnvironmentMaps;
    this._shouldUpdateSpecularMapAtlas = true;
    this._specularEnvironmentMapAtlas = undefined;

    this._useDefaultSphericalHarmonics = false;
    this._useDefaultSpecularMaps = false;

    this._shouldRegenerateShaders = false;
  }

  Object.defineProperties(Model.prototype, {
    /**
     * The object for the glTF JSON, including properties with default values omitted
     * from the JSON provided to this model.
     *
     * @memberof Model.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @default undefined
     */
    gltf: {
      get: function () {
        return defined(this._cachedGltf) ? this._cachedGltf.gltf : undefined;
      },
    },

    /**
     * When <code>true</code>, the glTF JSON is not stored with the model once the model is
     * loaded (when {@link Model#ready} is <code>true</code>).  This saves memory when
     * geometry, textures, and animations are embedded in the .gltf file.
     * This is especially useful for cases like 3D buildings, where each .gltf model is unique
     * and caching the glTF JSON is not effective.
     *
     * @memberof Model.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     *
     * @private
     */
    releaseGltfJson: {
      get: function () {
        return this._releaseGltfJson;
      },
    },

    /**
     * The key identifying this model in the model cache for glTF JSON, renderer resources, and animations.
     * Caching saves memory and improves loading speed when several models with the same url are created.
     * <p>
     * This key is automatically generated when the model is created with {@link Model.fromGltf}.  If the model
     * is created directly from glTF JSON using the {@link Model} constructor, this key can be manually
     * provided; otherwise, the model will not be changed.
     * </p>
     *
     * @memberof Model.prototype
     *
     * @type {String}
     * @readonly
     *
     * @private
     */
    cacheKey: {
      get: function () {
        return this._cacheKey;
      },
    },

    /**
     * The base path that paths in the glTF JSON are relative to.  The base
     * path is the same path as the path containing the .gltf file
     * minus the .gltf file, when binary, image, and shader files are
     * in the same directory as the .gltf.  When this is <code>''</code>,
     * the app's base path is used.
     *
     * @memberof Model.prototype
     *
     * @type {String}
     * @readonly
     *
     * @default ''
     */
    basePath: {
      get: function () {
        return this._resource.url;
      },
    },

    /**
     * The model's bounding sphere in its local coordinate system.  This does not take into
     * account glTF animations and skins nor does it take into account {@link Model#minimumPixelSize}.
     *
     * @memberof Model.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     *
     * @default undefined
     *
     * @exception {DeveloperError} The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true.
     *
     * @example
     * // Center in WGS84 coordinates
     * var center = Cesium.Matrix4.multiplyByPoint(model.modelMatrix, model.boundingSphere.center, new Cesium.Cartesian3());
     */
    boundingSphere: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (this._state !== ModelState$1.LOADED) {
          throw new DeveloperError(
            "The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true."
          );
        }
        //>>includeEnd('debug');

        var modelMatrix = this.modelMatrix;
        if (
          this.heightReference !== HeightReference$1.NONE &&
          this._clampedModelMatrix
        ) {
          modelMatrix = this._clampedModelMatrix;
        }

        var nonUniformScale = Matrix4.getScale(
          modelMatrix,
          boundingSphereCartesian3Scratch$1
        );
        var scale = defined(this.maximumScale)
          ? Math.min(this.maximumScale, this.scale)
          : this.scale;
        Cartesian3.multiplyByScalar(nonUniformScale, scale, nonUniformScale);

        var scaledBoundingSphere = this._scaledBoundingSphere;
        scaledBoundingSphere.center = Cartesian3.multiplyComponents(
          this._boundingSphere.center,
          nonUniformScale,
          scaledBoundingSphere.center
        );
        scaledBoundingSphere.radius =
          Cartesian3.maximumComponent(nonUniformScale) * this._initialRadius;

        if (defined(this._rtcCenter)) {
          Cartesian3.add(
            this._rtcCenter,
            scaledBoundingSphere.center,
            scaledBoundingSphere.center
          );
        }

        return scaledBoundingSphere;
      },
    },

    /**
     * When <code>true</code>, this model is ready to render, i.e., the external binary, image,
     * and shader files were downloaded and the WebGL resources were created.  This is set to
     * <code>true</code> right before {@link Model#readyPromise} is resolved.
     *
     * @memberof Model.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets the promise that will be resolved when this model is ready to render, i.e., when the external binary, image,
     * and shader files were downloaded and the WebGL resources were created.
     * <p>
     * This promise is resolved at the end of the frame before the first frame the model is rendered in.
     * </p>
     *
     * @memberof Model.prototype
     * @type {Promise.<Model>}
     * @readonly
     *
     * @example
     * // Play all animations at half-speed when the model is ready to render
     * Cesium.when(model.readyPromise).then(function(model) {
     *   model.activeAnimations.addAll({
     *     multiplier : 0.5
     *   });
     * }).otherwise(function(error){
     *   window.alert(error);
     * });
     *
     * @see Model#ready
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Determines if model WebGL resource creation will be spread out over several frames or
     * block until completion once all glTF files are loaded.
     *
     * @memberof Model.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    asynchronous: {
      get: function () {
        return this._asynchronous;
      },
    },

    /**
     * When <code>true</code>, each glTF mesh and primitive is pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
     *
     * @memberof Model.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    allowPicking: {
      get: function () {
        return this._allowPicking;
      },
    },

    /**
     * Determine if textures may continue to stream in after the model is loaded.
     *
     * @memberof Model.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    incrementallyLoadTextures: {
      get: function () {
        return this._incrementallyLoadTextures;
      },
    },

    /**
     * Return the number of pending texture loads.
     *
     * @memberof Model.prototype
     *
     * @type {Number}
     * @readonly
     */
    pendingTextureLoads: {
      get: function () {
        return defined(this._loadResources)
          ? this._loadResources.pendingTextureLoads
          : 0;
      },
    },

    /**
     * Returns true if the model was transformed this frame
     *
     * @memberof Model.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    dirty: {
      get: function () {
        return this._dirty;
      },
    },

    /**
     * Gets or sets the condition specifying at what distance from the camera that this model will be displayed.
     * @memberof Model.prototype
     * @type {DistanceDisplayCondition}
     * @default undefined
     */
    distanceDisplayCondition: {
      get: function () {
        return this._distanceDisplayCondition;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError("far must be greater than near");
        }
        //>>includeEnd('debug');
        this._distanceDisplayCondition = DistanceDisplayCondition.clone(
          value,
          this._distanceDisplayCondition
        );
      },
    },

    extensionsUsed: {
      get: function () {
        if (!defined(this._extensionsUsed)) {
          this._extensionsUsed = ModelUtility.getUsedExtensions(this.gltf);
        }
        return this._extensionsUsed;
      },
    },

    extensionsRequired: {
      get: function () {
        if (!defined(this._extensionsRequired)) {
          this._extensionsRequired = ModelUtility.getRequiredExtensions(
            this.gltf
          );
        }
        return this._extensionsRequired;
      },
    },

    /**
     * Gets the model's up-axis.
     * By default models are y-up according to the glTF spec, however geo-referenced models will typically be z-up.
     *
     * @memberof Model.prototype
     *
     * @type {Number}
     * @default Axis.Y
     * @readonly
     *
     * @private
     */
    upAxis: {
      get: function () {
        return this._upAxis;
      },
    },

    /**
     * Gets the model's forward axis.
     * By default, glTF 2.0 models are z-forward according to the glTF spec, however older
     * glTF (1.0, 0.8) models used x-forward.  Note that only Axis.X and Axis.Z are supported.
     *
     * @memberof Model.prototype
     *
     * @type {Number}
     * @default Axis.Z
     * @readonly
     *
     * @private
     */
    forwardAxis: {
      get: function () {
        if (defined(this._forwardAxis)) {
          return this._forwardAxis;
        }
        return this._gltfForwardAxis;
      },
    },

    /**
     * Gets the model's triangle count.
     *
     * @private
     */
    trianglesLength: {
      get: function () {
        return this._trianglesLength;
      },
    },

    /**
     * Gets the model's geometry memory in bytes. This includes all vertex and index buffers.
     *
     * @private
     */
    geometryByteLength: {
      get: function () {
        return this._geometryByteLength;
      },
    },

    /**
     * Gets the model's texture memory in bytes.
     *
     * @private
     */
    texturesByteLength: {
      get: function () {
        return this._texturesByteLength;
      },
    },

    /**
     * Gets the model's cached geometry memory in bytes. This includes all vertex and index buffers.
     *
     * @private
     */
    cachedGeometryByteLength: {
      get: function () {
        return this._cachedGeometryByteLength;
      },
    },

    /**
     * Gets the model's cached texture memory in bytes.
     *
     * @private
     */
    cachedTexturesByteLength: {
      get: function () {
        return this._cachedTexturesByteLength;
      },
    },

    /**
     * The {@link ClippingPlaneCollection} used to selectively disable rendering the model.
     *
     * @memberof Model.prototype
     *
     * @type {ClippingPlaneCollection}
     */
    clippingPlanes: {
      get: function () {
        return this._clippingPlanes;
      },
      set: function (value) {
        if (value === this._clippingPlanes) {
          return;
        }
        // Handle destroying, checking of unknown, checking for existing ownership
        ClippingPlaneCollection.setOwner(value, this, "_clippingPlanes");
      },
    },

    /**
     * @private
     */
    pickIds: {
      get: function () {
        return this._pickIds;
      },
    },

    /**
     * Cesium adds lighting from the earth, sky, atmosphere, and star skybox. This cartesian is used to scale the final
     * diffuse and specular lighting contribution from those sources to the final color. A value of 0.0 will disable those light sources.
     *
     * @memberof Model.prototype
     *
     * @type {Cartesian2}
     * @default Cartesian2(1.0, 1.0)
     */
    imageBasedLightingFactor: {
      get: function () {
        return this._imageBasedLightingFactor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.object("imageBasedLightingFactor", value);
        Check.typeOf.number.greaterThanOrEquals(
          "imageBasedLightingFactor.x",
          value.x,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "imageBasedLightingFactor.x",
          value.x,
          1.0
        );
        Check.typeOf.number.greaterThanOrEquals(
          "imageBasedLightingFactor.y",
          value.y,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "imageBasedLightingFactor.y",
          value.y,
          1.0
        );
        //>>includeEnd('debug');
        var imageBasedLightingFactor = this._imageBasedLightingFactor;
        if (
          value === imageBasedLightingFactor ||
          Cartesian2.equals(value, imageBasedLightingFactor)
        ) {
          return;
        }
        this._shouldRegenerateShaders =
          this._shouldRegenerateShaders ||
          (this._imageBasedLightingFactor.x > 0.0 && value.x === 0.0) ||
          (this._imageBasedLightingFactor.x === 0.0 && value.x > 0.0);
        this._shouldRegenerateShaders =
          this._shouldRegenerateShaders ||
          (this._imageBasedLightingFactor.y > 0.0 && value.y === 0.0) ||
          (this._imageBasedLightingFactor.y === 0.0 && value.y > 0.0);
        Cartesian2.clone(value, this._imageBasedLightingFactor);
      },
    },

    /**
     * The light color when shading the model. When <code>undefined</code> the scene's light color is used instead.
     * <p>
     * For example, disabling additional light sources by setting <code>model.imageBasedLightingFactor = new Cesium.Cartesian2(0.0, 0.0)</code> will make the
     * model much darker. Here, increasing the intensity of the light source will make the model brighter.
     * </p>
     *
     * @memberof Model.prototype
     *
     * @type {Cartesian3}
     * @default undefined
     */
    lightColor: {
      get: function () {
        return this._lightColor;
      },
      set: function (value) {
        var lightColor = this._lightColor;
        if (value === lightColor || Cartesian3.equals(value, lightColor)) {
          return;
        }
        this._shouldRegenerateShaders =
          this._shouldRegenerateShaders ||
          (defined(lightColor) && !defined(value)) ||
          (defined(value) && !defined(lightColor));
        this._lightColor = Cartesian3.clone(value, lightColor);
      },
    },

    /**
     * The sun's luminance at the zenith in kilo candela per meter squared to use for this model's procedural environment map.
     * This is used when {@link Model#specularEnvironmentMaps} and {@link Model#sphericalHarmonicCoefficients} are not defined.
     *
     * @memberof Model.prototype
     *
     * @demo {@link https://sandcastle.cesium.com/index.html?src=Image-Based Lighting.html|Sandcastle Image Based Lighting Demo}
     * @type {Number}
     * @default 0.2
     */
    luminanceAtZenith: {
      get: function () {
        return this._luminanceAtZenith;
      },
      set: function (value) {
        var lum = this._luminanceAtZenith;
        if (value === lum) {
          return;
        }
        this._shouldRegenerateShaders =
          this._shouldRegenerateShaders ||
          (defined(lum) && !defined(value)) ||
          (defined(value) && !defined(lum));
        this._luminanceAtZenith = value;
      },
    },

    /**
     * The third order spherical harmonic coefficients used for the diffuse color of image-based lighting. When <code>undefined</code>, a diffuse irradiance
     * computed from the atmosphere color is used.
     * <p>
     * There are nine <code>Cartesian3</code> coefficients.
     * The order of the coefficients is: L<sub>00</sub>, L<sub>1-1</sub>, L<sub>10</sub>, L<sub>11</sub>, L<sub>2-2</sub>, L<sub>2-1</sub>, L<sub>20</sub>, L<sub>21</sub>, L<sub>22</sub>
     * </p>
     *
     * These values can be obtained by preprocessing the environment map using the <code>cmgen</code> tool of
     * {@link https://github.com/google/filament/releases|Google's Filament project}. This will also generate a KTX file that can be
     * supplied to {@link Model#specularEnvironmentMaps}.
     *
     * @memberof Model.prototype
     *
     * @type {Cartesian3[]}
     * @demo {@link https://sandcastle.cesium.com/index.html?src=Image-Based Lighting.html|Sandcastle Image Based Lighting Demo}
     * @see {@link https://graphics.stanford.edu/papers/envmap/envmap.pdf|An Efficient Representation for Irradiance Environment Maps}
     */
    sphericalHarmonicCoefficients: {
      get: function () {
        return this._sphericalHarmonicCoefficients;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && (!Array.isArray(value) || value.length !== 9)) {
          throw new DeveloperError(
            "sphericalHarmonicCoefficients must be an array of 9 Cartesian3 values."
          );
        }
        //>>includeEnd('debug');
        if (value === this._sphericalHarmonicCoefficients) {
          return;
        }
        this._sphericalHarmonicCoefficients = value;
        this._shouldRegenerateShaders = true;
      },
    },

    /**
     * A URL to a KTX file that contains a cube map of the specular lighting and the convoluted specular mipmaps.
     *
     * @memberof Model.prototype
     * @demo {@link https://sandcastle.cesium.com/index.html?src=Image-Based Lighting.html|Sandcastle Image Based Lighting Demo}
     * @type {String}
     * @see Model#sphericalHarmonicCoefficients
     */
    specularEnvironmentMaps: {
      get: function () {
        return this._specularEnvironmentMaps;
      },
      set: function (value) {
        this._shouldUpdateSpecularMapAtlas =
          this._shouldUpdateSpecularMapAtlas ||
          value !== this._specularEnvironmentMaps;
        this._specularEnvironmentMaps = value;
      },
    },
    /**
     * Gets the credit that will be displayed for the model
     * @memberof Model.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },
  });

  function silhouetteSupported(context) {
    return context.stencilBuffer;
  }

  function isColorShadingEnabled(model) {
    return (
      !Color.equals(model.color, Color.WHITE) ||
      model.colorBlendMode !== ColorBlendMode$1.HIGHLIGHT
    );
  }

  function isClippingEnabled(model) {
    var clippingPlanes = model._clippingPlanes;
    return (
      defined(clippingPlanes) &&
      clippingPlanes.enabled &&
      clippingPlanes.length !== 0
    );
  }

  /**
   * Determines if silhouettes are supported.
   *
   * @param {Scene} scene The scene.
   * @returns {Boolean} <code>true</code> if silhouettes are supported; otherwise, returns <code>false</code>
   */
  Model.silhouetteSupported = function (scene) {
    return silhouetteSupported(scene.context);
  };

  function containsGltfMagic(uint8Array) {
    var magic = getMagic(uint8Array);
    return magic === "glTF";
  }

  /**
   * <p>
   * Creates a model from a glTF asset.  When the model is ready to render, i.e., when the external binary, image,
   * and shader files are downloaded and the WebGL resources are created, the {@link Model#readyPromise} is resolved.
   * </p>
   * <p>
   * The model can be a traditional glTF asset with a .gltf extension or a Binary glTF using the .glb extension.
   * </p>
   * <p>
   * Cesium supports glTF assets with the following extensions:
   * <ul>
   * <li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Khronos/KHR_binary_glTF/README.md|KHR_binary_glTF (glTF 1.0)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Khronos/KHR_materials_common/README.md|KHR_materials_common (glTF 1.0)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Vendor/WEB3D_quantized_attributes/README.md|WEB3D_quantized_attributes (glTF 1.0)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/AGI_articulations/README.md|AGI_articulations}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/pull/1302|KHR_blend (draft)}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_draco_mesh_compression/README.md|KHR_draco_mesh_compression}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness/README.md|KHR_materials_pbrSpecularGlossiness}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit/README.md|KHR_materials_unlit}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_techniques_webgl/README.md|KHR_techniques_webgl}
   * </li><li>
   * {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_texture_transform/README.md|KHR_texture_transform}
   * </li>
   * </ul>
   * </p>
   * <p>
   * For high-precision rendering, Cesium supports the {@link https://github.com/KhronosGroup/glTF/blob/master/extensions/1.0/Vendor/CESIUM_RTC/README.md|CESIUM_RTC} extension, which introduces the
   * CESIUM_RTC_MODELVIEW parameter semantic that says the node is in WGS84 coordinates translated
   * relative to a local origin.
   * </p>
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String} options.url The url to the .gltf file.
   * @param {Resource|String} [options.basePath] The base path that paths in the glTF JSON are relative to.
   * @param {Boolean} [options.show=true] Determines if the model primitive will be shown.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the model from model to world coordinates.
   * @param {Number} [options.scale=1.0] A uniform scale applied to this model.
   * @param {Number} [options.minimumPixelSize=0.0] The approximate minimum pixel size of the model regardless of zoom.
   * @param {Number} [options.maximumScale] The maximum scale for the model.
   * @param {Object} [options.id] A user-defined object to return when the model is picked with {@link Scene#pick}.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each glTF mesh and primitive is pickable with {@link Scene#pick}.
   * @param {Boolean} [options.incrementallyLoadTextures=true] Determine if textures may continue to stream in after the model is loaded.
   * @param {Boolean} [options.asynchronous=true] Determines if model WebGL resource creation will be spread out over several frames or block until completion once all glTF files are loaded.
   * @param {Boolean} [options.clampAnimations=true] Determines if the model's animations should hold a pose over frames where no keyframes are specified.
   * @param {ShadowMode} [options.shadows=ShadowMode.ENABLED] Determines whether the model casts or receives shadows from light sources.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Draws the bounding sphere for each draw command in the model.
   * @param {Boolean} [options.debugWireframe=false] For debugging only. Draws the model in wireframe.
   * @param {HeightReference} [options.heightReference=HeightReference.NONE] Determines how the model is drawn relative to terrain.
   * @param {Scene} [options.scene] Must be passed in for models that use the height reference property.
   * @param {DistanceDisplayCondition} [options.distanceDisplayCondition] The condition specifying at what distance from the camera that this model will be displayed.
   * @param {Color} [options.color=Color.WHITE] A color that blends with the model's rendered color.
   * @param {ColorBlendMode} [options.colorBlendMode=ColorBlendMode.HIGHLIGHT] Defines how the color blends with the model.
   * @param {Number} [options.colorBlendAmount=0.5] Value used to determine the color strength when the <code>colorBlendMode</code> is <code>MIX</code>. A value of 0.0 results in the model's rendered color while a value of 1.0 results in a solid color, with any value in-between resulting in a mix of the two.
   * @param {Color} [options.silhouetteColor=Color.RED] The silhouette color. If more than 256 models have silhouettes enabled, there is a small chance that overlapping models will have minor artifacts.
   * @param {Number} [options.silhouetteSize=0.0] The size of the silhouette in pixels.
   * @param {ClippingPlaneCollection} [options.clippingPlanes] The {@link ClippingPlaneCollection} used to selectively disable rendering the model.
   * @param {Boolean} [options.dequantizeInShader=true] Determines if a {@link https://github.com/google/draco|Draco} encoded model is dequantized on the GPU. This decreases total memory usage for encoded models.
   * @param {Credit|String} [options.credit] A credit for the model, which is displayed on the canvas.
   * @param {Boolean} [options.backFaceCulling=true] Whether to cull back-facing geometry. When true, back face culling is determined by the material's doubleSided property; when false, back face culling is disabled. Back faces are not culled if {@link Model#color} is translucent or {@link Model#silhouetteSize} is greater than 0.0.
   *
   * @returns {Model} The newly created model.
   *
   * @example
   * // Example 1. Create a model from a glTF asset
   * var model = scene.primitives.add(Cesium.Model.fromGltf({
   *   url : './duck/duck.gltf'
   * }));
   *
   * @example
   * // Example 2. Create model and provide all properties and events
   * var origin = Cesium.Cartesian3.fromDegrees(-95.0, 40.0, 200000.0);
   * var modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
   *
   * var model = scene.primitives.add(Cesium.Model.fromGltf({
   *   url : './duck/duck.gltf',
   *   show : true,                     // default
   *   modelMatrix : modelMatrix,
   *   scale : 2.0,                     // double size
   *   minimumPixelSize : 128,          // never smaller than 128 pixels
   *   maximumScale: 20000,             // never larger than 20000 * model size (overrides minimumPixelSize)
   *   allowPicking : false,            // not pickable
   *   debugShowBoundingVolume : false, // default
   *   debugWireframe : false
   * }));
   *
   * model.readyPromise.then(function(model) {
   *   // Play all animations when the model is ready to render
   *   model.activeAnimations.addAll();
   * });
   */
  Model.fromGltf = function (options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.url)) {
      throw new DeveloperError("options.url is required");
    }
    //>>includeEnd('debug');

    var url = options.url;
    options = clone(options);

    // Create resource for the model file
    var modelResource = Resource.createIfNeeded(url);

    // Setup basePath to get dependent files
    var basePath = defaultValue(options.basePath, modelResource.clone());
    var resource = Resource.createIfNeeded(basePath);

    // If no cache key is provided, use a GUID.
    // Check using a URI to GUID dictionary that we have not already added this model.
    var cacheKey = defaultValue(
      options.cacheKey,
      uriToGuid[getAbsoluteUri(modelResource.url)]
    );
    if (!defined(cacheKey)) {
      cacheKey = createGuid();
      uriToGuid[getAbsoluteUri(modelResource.url)] = cacheKey;
    }

    if (defined(options.basePath) && !defined(options.cacheKey)) {
      cacheKey += resource.url;
    }
    options.cacheKey = cacheKey;
    options.basePath = resource;

    var model = new Model(options);

    var cachedGltf = gltfCache[cacheKey];
    if (!defined(cachedGltf)) {
      cachedGltf = new CachedGltf({
        ready: false,
      });
      cachedGltf.count = 1;
      cachedGltf.modelsToLoad.push(model);
      setCachedGltf(model, cachedGltf);
      gltfCache[cacheKey] = cachedGltf;

      // Add Accept header if we need it
      if (!defined(modelResource.headers.Accept)) {
        modelResource.headers.Accept = defaultModelAccept;
      }

      modelResource
        .fetchArrayBuffer()
        .then(function (arrayBuffer) {
          var array = new Uint8Array(arrayBuffer);
          if (containsGltfMagic(array)) {
            // Load binary glTF
            var parsedGltf = parseGlb(array);
            cachedGltf.makeReady(parsedGltf);
          } else {
            // Load text (JSON) glTF
            var json = getStringFromTypedArray(array);
            cachedGltf.makeReady(JSON.parse(json));
          }

          var resourceCredits = model._resourceCredits;
          var credits = modelResource.credits;
          if (defined(credits)) {
            var length = credits.length;
            for (var i = 0; i < length; i++) {
              resourceCredits.push(credits[i]);
            }
          }
        })
        .otherwise(
          ModelUtility.getFailedLoadFunction(model, "model", modelResource.url)
        );
    } else if (!cachedGltf.ready) {
      // Cache hit but the fetchArrayBuffer() or fetchText() request is still pending
      ++cachedGltf.count;
      cachedGltf.modelsToLoad.push(model);
    }
    // else if the cached glTF is defined and ready, the
    // model constructor will pick it up using the cache key.

    return model;
  };

  /**
   * For the unit tests to verify model caching.
   *
   * @private
   */
  Model._gltfCache = gltfCache;

  function getRuntime(model, runtimeName, name) {
    //>>includeStart('debug', pragmas.debug);
    if (model._state !== ModelState$1.LOADED) {
      throw new DeveloperError(
        "The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true."
      );
    }

    if (!defined(name)) {
      throw new DeveloperError("name is required.");
    }
    //>>includeEnd('debug');

    return model._runtime[runtimeName][name];
  }

  /**
   * Returns the glTF node with the given <code>name</code> property.  This is used to
   * modify a node's transform for animation outside of glTF animations.
   *
   * @param {String} name The glTF name of the node.
   * @returns {ModelNode} The node or <code>undefined</code> if no node with <code>name</code> exists.
   *
   * @exception {DeveloperError} The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true.
   *
   * @example
   * // Apply non-uniform scale to node LOD3sp
   * var node = model.getNode('LOD3sp');
   * node.matrix = Cesium.Matrix4.fromScale(new Cesium.Cartesian3(5.0, 1.0, 1.0), node.matrix);
   */
  Model.prototype.getNode = function (name) {
    var node = getRuntime(this, "nodesByName", name);
    return defined(node) ? node.publicNode : undefined;
  };

  /**
   * Returns the glTF mesh with the given <code>name</code> property.
   *
   * @param {String} name The glTF name of the mesh.
   *
   * @returns {ModelMesh} The mesh or <code>undefined</code> if no mesh with <code>name</code> exists.
   *
   * @exception {DeveloperError} The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true.
   */
  Model.prototype.getMesh = function (name) {
    return getRuntime(this, "meshesByName", name);
  };

  /**
   * Returns the glTF material with the given <code>name</code> property.
   *
   * @param {String} name The glTF name of the material.
   * @returns {ModelMaterial} The material or <code>undefined</code> if no material with <code>name</code> exists.
   *
   * @exception {DeveloperError} The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true.
   */
  Model.prototype.getMaterial = function (name) {
    return getRuntime(this, "materialsByName", name);
  };

  /**
   * Sets the current value of an articulation stage.  After setting one or multiple stage values, call
   * Model.applyArticulations() to cause the node matrices to be recalculated.
   *
   * @param {String} articulationStageKey The name of the articulation, a space, and the name of the stage.
   * @param {Number} value The numeric value of this stage of the articulation.
   *
   * @exception {DeveloperError} The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true.
   *
   * @see Model#applyArticulations
   */
  Model.prototype.setArticulationStage = function (articulationStageKey, value) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("value", value);
    //>>includeEnd('debug');

    var stage = getRuntime(this, "stagesByKey", articulationStageKey);
    var articulation = getRuntime(
      this,
      "articulationsByStageKey",
      articulationStageKey
    );
    if (defined(stage) && defined(articulation)) {
      value = CesiumMath.clamp(value, stage.minimumValue, stage.maximumValue);
      if (
        !CesiumMath.equalsEpsilon(stage.currentValue, value, articulationEpsilon)
      ) {
        stage.currentValue = value;
        articulation.isDirty = true;
      }
    }
  };

  var scratchArticulationCartesian = new Cartesian3();
  var scratchArticulationRotation = new Matrix3();

  /**
   * Modifies a Matrix4 by applying a transformation for a given value of a stage.  Note this is different usage
   * from the typical <code>result</code> parameter, in that the incoming value of <code>result</code> is
   * meaningful.  Various stages of an articulation can be multiplied together, so their
   * transformations are all merged into a composite Matrix4 representing them all.
   *
   * @param {object} stage The stage of an articulation that is being evaluated.
   * @param {Matrix4} result The matrix to be modified.
   * @returns {Matrix4} A matrix transformed as requested by the articulation stage.
   *
   * @private
   */
  function applyArticulationStageMatrix(stage, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("stage", stage);
    Check.typeOf.object("result", result);
    //>>includeEnd('debug');

    var value = stage.currentValue;
    var cartesian = scratchArticulationCartesian;
    var rotation;
    switch (stage.type) {
      case "xRotate":
        rotation = Matrix3.fromRotationX(
          CesiumMath.toRadians(value),
          scratchArticulationRotation
        );
        Matrix4.multiplyByMatrix3(result, rotation, result);
        break;
      case "yRotate":
        rotation = Matrix3.fromRotationY(
          CesiumMath.toRadians(value),
          scratchArticulationRotation
        );
        Matrix4.multiplyByMatrix3(result, rotation, result);
        break;
      case "zRotate":
        rotation = Matrix3.fromRotationZ(
          CesiumMath.toRadians(value),
          scratchArticulationRotation
        );
        Matrix4.multiplyByMatrix3(result, rotation, result);
        break;
      case "xTranslate":
        cartesian.x = value;
        cartesian.y = 0.0;
        cartesian.z = 0.0;
        Matrix4.multiplyByTranslation(result, cartesian, result);
        break;
      case "yTranslate":
        cartesian.x = 0.0;
        cartesian.y = value;
        cartesian.z = 0.0;
        Matrix4.multiplyByTranslation(result, cartesian, result);
        break;
      case "zTranslate":
        cartesian.x = 0.0;
        cartesian.y = 0.0;
        cartesian.z = value;
        Matrix4.multiplyByTranslation(result, cartesian, result);
        break;
      case "xScale":
        cartesian.x = value;
        cartesian.y = 1.0;
        cartesian.z = 1.0;
        Matrix4.multiplyByScale(result, cartesian, result);
        break;
      case "yScale":
        cartesian.x = 1.0;
        cartesian.y = value;
        cartesian.z = 1.0;
        Matrix4.multiplyByScale(result, cartesian, result);
        break;
      case "zScale":
        cartesian.x = 1.0;
        cartesian.y = 1.0;
        cartesian.z = value;
        Matrix4.multiplyByScale(result, cartesian, result);
        break;
      case "uniformScale":
        Matrix4.multiplyByUniformScale(result, value, result);
        break;
    }
    return result;
  }

  var scratchApplyArticulationTransform = new Matrix4();

  /**
   * Applies any modified articulation stages to the matrix of each node that participates
   * in any articulation.  Note that this will overwrite any nodeTransformations on participating nodes.
   *
   * @exception {DeveloperError} The model is not loaded.  Use Model.readyPromise or wait for Model.ready to be true.
   */
  Model.prototype.applyArticulations = function () {
    var articulationsByName = this._runtime.articulationsByName;
    for (var articulationName in articulationsByName) {
      if (articulationsByName.hasOwnProperty(articulationName)) {
        var articulation = articulationsByName[articulationName];
        if (articulation.isDirty) {
          articulation.isDirty = false;
          var numNodes = articulation.nodes.length;
          for (var n = 0; n < numNodes; ++n) {
            var node = articulation.nodes[n];
            var transform = Matrix4.clone(
              node.originalMatrix,
              scratchApplyArticulationTransform
            );

            var numStages = articulation.stages.length;
            for (var s = 0; s < numStages; ++s) {
              var stage = articulation.stages[s];
              transform = applyArticulationStageMatrix(stage, transform);
            }
            node.matrix = transform;
          }
        }
      }
    }
  };

  ///////////////////////////////////////////////////////////////////////////

  function addBuffersToLoadResources$1(model) {
    var gltf = model.gltf;
    var loadResources = model._loadResources;
    ForEach.buffer(gltf, function (buffer, id) {
      loadResources.buffers[id] = buffer.extras._pipeline.source;
    });
  }

  function bufferLoad(model, id) {
    return function (arrayBuffer) {
      var loadResources = model._loadResources;
      var buffer = new Uint8Array(arrayBuffer);
      --loadResources.pendingBufferLoads;
      model.gltf.buffers[id].extras._pipeline.source = buffer;
    };
  }

  function parseBufferViews$1(model) {
    var bufferViews = model.gltf.bufferViews;
    var vertexBuffersToCreate = model._loadResources.vertexBuffersToCreate;

    // Only ARRAY_BUFFER here.  ELEMENT_ARRAY_BUFFER created below.
    ForEach.bufferView(model.gltf, function (bufferView, id) {
      if (bufferView.target === WebGLConstants$1.ARRAY_BUFFER) {
        vertexBuffersToCreate.enqueue(id);
      }
    });

    var indexBuffersToCreate = model._loadResources.indexBuffersToCreate;
    var indexBufferIds = {};

    // The Cesium Renderer requires knowing the datatype for an index buffer
    // at creation type, which is not part of the glTF bufferview so loop
    // through glTF accessors to create the bufferview's index buffer.
    ForEach.accessor(model.gltf, function (accessor) {
      var bufferViewId = accessor.bufferView;
      if (!defined(bufferViewId)) {
        return;
      }

      var bufferView = bufferViews[bufferViewId];
      if (
        bufferView.target === WebGLConstants$1.ELEMENT_ARRAY_BUFFER &&
        !defined(indexBufferIds[bufferViewId])
      ) {
        indexBufferIds[bufferViewId] = true;
        indexBuffersToCreate.enqueue({
          id: bufferViewId,
          componentType: accessor.componentType,
        });
      }
    });
  }

  function parseTechniques(model) {
    // retain references to gltf techniques
    var gltf = model.gltf;
    if (!hasExtension(gltf, "KHR_techniques_webgl")) {
      return;
    }

    var sourcePrograms = model._sourcePrograms;
    var sourceTechniques = model._sourceTechniques;
    var programs = gltf.extensions.KHR_techniques_webgl.programs;

    ForEach.technique(gltf, function (technique, techniqueId) {
      sourceTechniques[techniqueId] = clone(technique);

      var programId = technique.program;
      if (!defined(sourcePrograms[programId])) {
        sourcePrograms[programId] = clone(programs[programId]);
      }
    });
  }

  function shaderLoad(model, type, id) {
    return function (source) {
      var loadResources = model._loadResources;
      loadResources.shaders[id] = {
        source: source,
        type: type,
        bufferView: undefined,
      };
      --loadResources.pendingShaderLoads;
      model._rendererResources.sourceShaders[id] = source;
    };
  }

  function parseShaders(model) {
    var gltf = model.gltf;
    var buffers = gltf.buffers;
    var bufferViews = gltf.bufferViews;
    var sourceShaders = model._rendererResources.sourceShaders;
    ForEach.shader(gltf, function (shader, id) {
      // Shader references either uri (external or base64-encoded) or bufferView
      if (defined(shader.bufferView)) {
        var bufferViewId = shader.bufferView;
        var bufferView = bufferViews[bufferViewId];
        var bufferId = bufferView.buffer;
        var buffer = buffers[bufferId];
        var source = getStringFromTypedArray(
          buffer.extras._pipeline.source,
          bufferView.byteOffset,
          bufferView.byteLength
        );
        sourceShaders[id] = source;
      } else if (defined(shader.extras._pipeline.source)) {
        sourceShaders[id] = shader.extras._pipeline.source;
      } else {
        ++model._loadResources.pendingShaderLoads;

        var shaderResource = model._resource.getDerivedResource({
          url: shader.uri,
        });

        shaderResource
          .fetchText()
          .then(shaderLoad(model, shader.type, id))
          .otherwise(
            ModelUtility.getFailedLoadFunction(
              model,
              "shader",
              shaderResource.url
            )
          );
      }
    });
  }

  function parsePrograms(model) {
    var sourceTechniques = model._sourceTechniques;
    for (var techniqueId in sourceTechniques) {
      if (sourceTechniques.hasOwnProperty(techniqueId)) {
        var technique = sourceTechniques[techniqueId];
        model._loadResources.programsToCreate.enqueue({
          programId: technique.program,
          techniqueId: techniqueId,
        });
      }
    }
  }

  function parseArticulations(model) {
    var articulationsByName = {};
    var articulationsByStageKey = {};
    var runtimeStagesByKey = {};

    model._runtime.articulationsByName = articulationsByName;
    model._runtime.articulationsByStageKey = articulationsByStageKey;
    model._runtime.stagesByKey = runtimeStagesByKey;

    var gltf = model.gltf;
    if (
      !hasExtension(gltf, "AGI_articulations") ||
      !defined(gltf.extensions) ||
      !defined(gltf.extensions.AGI_articulations)
    ) {
      return;
    }

    var gltfArticulations = gltf.extensions.AGI_articulations.articulations;
    if (!defined(gltfArticulations)) {
      return;
    }

    var numArticulations = gltfArticulations.length;
    for (var i = 0; i < numArticulations; ++i) {
      var articulation = clone(gltfArticulations[i]);
      articulation.nodes = [];
      articulation.isDirty = true;
      articulationsByName[articulation.name] = articulation;

      var numStages = articulation.stages.length;
      for (var s = 0; s < numStages; ++s) {
        var stage = articulation.stages[s];
        stage.currentValue = stage.initialValue;

        var stageKey = articulation.name + " " + stage.name;
        articulationsByStageKey[stageKey] = articulation;
        runtimeStagesByKey[stageKey] = stage;
      }
    }
  }

  function imageLoad(model, textureId) {
    return function (image) {
      var loadResources = model._loadResources;
      --loadResources.pendingTextureLoads;
      loadResources.texturesToCreate.enqueue({
        id: textureId,
        image: image,
        bufferView: image.bufferView,
        width: image.width,
        height: image.height,
        internalFormat: image.internalFormat,
      });
    };
  }

  var ktxRegex$1 = /(^data:image\/ktx)|(\.ktx$)/i;
  var crnRegex$1 = /(^data:image\/crn)|(\.crn$)/i;

  function parseTextures(model, context, supportsWebP) {
    var gltf = model.gltf;
    var images = gltf.images;
    var uri;
    ForEach.texture(gltf, function (texture, id) {
      var imageId = texture.source;

      if (
        defined(texture.extensions) &&
        defined(texture.extensions.EXT_texture_webp) &&
        supportsWebP
      ) {
        imageId = texture.extensions.EXT_texture_webp.source;
      }

      var gltfImage = images[imageId];
      var extras = gltfImage.extras;

      var bufferViewId = gltfImage.bufferView;
      var mimeType = gltfImage.mimeType;
      uri = gltfImage.uri;

      // First check for a compressed texture
      if (defined(extras) && defined(extras.compressedImage3DTiles)) {
        var crunch = extras.compressedImage3DTiles.crunch;
        var s3tc = extras.compressedImage3DTiles.s3tc;
        var pvrtc = extras.compressedImage3DTiles.pvrtc1;
        var etc1 = extras.compressedImage3DTiles.etc1;

        if (context.s3tc && defined(crunch)) {
          mimeType = crunch.mimeType;
          if (defined(crunch.bufferView)) {
            bufferViewId = crunch.bufferView;
          } else {
            uri = crunch.uri;
          }
        } else if (context.s3tc && defined(s3tc)) {
          mimeType = s3tc.mimeType;
          if (defined(s3tc.bufferView)) {
            bufferViewId = s3tc.bufferView;
          } else {
            uri = s3tc.uri;
          }
        } else if (context.pvrtc && defined(pvrtc)) {
          mimeType = pvrtc.mimeType;
          if (defined(pvrtc.bufferView)) {
            bufferViewId = pvrtc.bufferView;
          } else {
            uri = pvrtc.uri;
          }
        } else if (context.etc1 && defined(etc1)) {
          mimeType = etc1.mimeType;
          if (defined(etc1.bufferView)) {
            bufferViewId = etc1.bufferView;
          } else {
            uri = etc1.uri;
          }
        }
      }

      // Image references either uri (external or base64-encoded) or bufferView
      if (defined(bufferViewId)) {
        model._loadResources.texturesToCreateFromBufferView.enqueue({
          id: id,
          image: undefined,
          bufferView: bufferViewId,
          mimeType: mimeType,
        });
      } else {
        ++model._loadResources.pendingTextureLoads;

        var imageResource = model._resource.getDerivedResource({
          url: uri,
        });

        var promise;
        if (ktxRegex$1.test(uri)) {
          promise = loadKTX(imageResource);
        } else if (crnRegex$1.test(uri)) {
          promise = loadCRN(imageResource);
        } else {
          promise = imageResource.fetchImage();
        }
        promise
          .then(imageLoad(model, id))
          .otherwise(
            ModelUtility.getFailedLoadFunction(model, "image", imageResource.url)
          );
      }
    });
  }

  var scratchArticulationStageInitialTransform = new Matrix4();

  function parseNodes(model) {
    var runtimeNodes = {};
    var runtimeNodesByName = {};
    var skinnedNodes = [];

    var skinnedNodesIds = model._loadResources.skinnedNodesIds;
    var articulationsByName = model._runtime.articulationsByName;

    ForEach.node(model.gltf, function (node, id) {
      var runtimeNode = {
        // Animation targets
        matrix: undefined,
        translation: undefined,
        rotation: undefined,
        scale: undefined,

        // Per-node show inherited from parent
        computedShow: true,

        // Computed transforms
        transformToRoot: new Matrix4(),
        computedMatrix: new Matrix4(),
        dirtyNumber: 0, // The frame this node was made dirty by an animation; for graph traversal

        // Rendering
        commands: [], // empty for transform, light, and camera nodes

        // Skinned node
        inverseBindMatrices: undefined, // undefined when node is not skinned
        bindShapeMatrix: undefined, // undefined when node is not skinned or identity
        joints: [], // empty when node is not skinned
        computedJointMatrices: [], // empty when node is not skinned

        // Joint node
        jointName: node.jointName, // undefined when node is not a joint

        weights: [],

        // Graph pointers
        children: [], // empty for leaf nodes
        parents: [], // empty for root nodes

        // Publicly-accessible ModelNode instance to modify animation targets
        publicNode: undefined,
      };
      runtimeNode.publicNode = new ModelNode(
        model,
        node,
        runtimeNode,
        id,
        ModelUtility.getTransform(node)
      );

      runtimeNodes[id] = runtimeNode;
      runtimeNodesByName[node.name] = runtimeNode;

      if (defined(node.skin)) {
        skinnedNodesIds.push(id);
        skinnedNodes.push(runtimeNode);
      }

      if (
        defined(node.extensions) &&
        defined(node.extensions.AGI_articulations)
      ) {
        var articulationName = node.extensions.AGI_articulations.articulationName;
        if (defined(articulationName)) {
          var transform = Matrix4.clone(
            runtimeNode.publicNode.originalMatrix,
            scratchArticulationStageInitialTransform
          );
          var articulation = articulationsByName[articulationName];
          articulation.nodes.push(runtimeNode.publicNode);

          var numStages = articulation.stages.length;
          for (var s = 0; s < numStages; ++s) {
            var stage = articulation.stages[s];
            transform = applyArticulationStageMatrix(stage, transform);
          }
          runtimeNode.publicNode.matrix = transform;
        }
      }
    });

    model._runtime.nodes = runtimeNodes;
    model._runtime.nodesByName = runtimeNodesByName;
    model._runtime.skinnedNodes = skinnedNodes;
  }

  function parseMaterials(model) {
    var gltf = model.gltf;
    var techniques = model._sourceTechniques;

    var runtimeMaterialsByName = {};
    var runtimeMaterialsById = {};
    var uniformMaps = model._uniformMaps;

    ForEach.material(gltf, function (material, materialId) {
      // Allocated now so ModelMaterial can keep a reference to it.
      uniformMaps[materialId] = {
        uniformMap: undefined,
        values: undefined,
        jointMatrixUniformName: undefined,
        morphWeightsUniformName: undefined,
      };

      var modelMaterial = new ModelMaterial(model, material, materialId);

      if (
        defined(material.extensions) &&
        defined(material.extensions.KHR_techniques_webgl)
      ) {
        var techniqueId = material.extensions.KHR_techniques_webgl.technique;
        modelMaterial._technique = techniqueId;
        modelMaterial._program = techniques[techniqueId].program;

        ForEach.materialValue(material, function (value, uniformName) {
          if (!defined(modelMaterial._values)) {
            modelMaterial._values = {};
          }

          modelMaterial._values[uniformName] = clone(value);
        });
      }

      runtimeMaterialsByName[material.name] = modelMaterial;
      runtimeMaterialsById[materialId] = modelMaterial;
    });

    model._runtime.materialsByName = runtimeMaterialsByName;
    model._runtime.materialsById = runtimeMaterialsById;
  }

  function parseMeshes(model) {
    var runtimeMeshesByName = {};
    var runtimeMaterialsById = model._runtime.materialsById;

    ForEach.mesh(model.gltf, function (mesh, meshId) {
      runtimeMeshesByName[mesh.name] = new ModelMesh(
        mesh,
        runtimeMaterialsById,
        meshId
      );
      if (
        defined(model.extensionsUsed.WEB3D_quantized_attributes) ||
        model._dequantizeInShader
      ) {
        // Cache primitives according to their program
        ForEach.meshPrimitive(mesh, function (primitive, primitiveId) {
          var programId = getProgramForPrimitive(model, primitive);
          var programPrimitives = model._programPrimitives[programId];
          if (!defined(programPrimitives)) {
            programPrimitives = {};
            model._programPrimitives[programId] = programPrimitives;
          }
          programPrimitives[meshId + ".primitive." + primitiveId] = primitive;
        });
      }
    });

    model._runtime.meshesByName = runtimeMeshesByName;
  }

  ///////////////////////////////////////////////////////////////////////////

  var CreateVertexBufferJob = function () {
    this.id = undefined;
    this.model = undefined;
    this.context = undefined;
  };

  CreateVertexBufferJob.prototype.set = function (id, model, context) {
    this.id = id;
    this.model = model;
    this.context = context;
  };

  CreateVertexBufferJob.prototype.execute = function () {
    createVertexBuffer$1(this.id, this.model, this.context);
  };

  ///////////////////////////////////////////////////////////////////////////

  function createVertexBuffer$1(bufferViewId, model, context) {
    var loadResources = model._loadResources;
    var bufferViews = model.gltf.bufferViews;
    var bufferView = bufferViews[bufferViewId];

    // Use bufferView created at runtime
    if (!defined(bufferView)) {
      bufferView = loadResources.createdBufferViews[bufferViewId];
    }

    var vertexBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: loadResources.getBuffer(bufferView),
      usage: BufferUsage$1.STATIC_DRAW,
    });
    vertexBuffer.vertexArrayDestroyable = false;
    model._rendererResources.buffers[bufferViewId] = vertexBuffer;
    model._geometryByteLength += vertexBuffer.sizeInBytes;
  }

  ///////////////////////////////////////////////////////////////////////////

  var CreateIndexBufferJob = function () {
    this.id = undefined;
    this.componentType = undefined;
    this.model = undefined;
    this.context = undefined;
  };

  CreateIndexBufferJob.prototype.set = function (
    id,
    componentType,
    model,
    context
  ) {
    this.id = id;
    this.componentType = componentType;
    this.model = model;
    this.context = context;
  };

  CreateIndexBufferJob.prototype.execute = function () {
    createIndexBuffer$1(this.id, this.componentType, this.model, this.context);
  };

  ///////////////////////////////////////////////////////////////////////////

  function createIndexBuffer$1(bufferViewId, componentType, model, context) {
    var loadResources = model._loadResources;
    var bufferViews = model.gltf.bufferViews;
    var bufferView = bufferViews[bufferViewId];

    // Use bufferView created at runtime
    if (!defined(bufferView)) {
      bufferView = loadResources.createdBufferViews[bufferViewId];
    }

    var indexBuffer = Buffer$1.createIndexBuffer({
      context: context,
      typedArray: loadResources.getBuffer(bufferView),
      usage: BufferUsage$1.STATIC_DRAW,
      indexDatatype: componentType,
    });
    indexBuffer.vertexArrayDestroyable = false;
    model._rendererResources.buffers[bufferViewId] = indexBuffer;
    model._geometryByteLength += indexBuffer.sizeInBytes;
  }

  var scratchVertexBufferJob = new CreateVertexBufferJob();
  var scratchIndexBufferJob = new CreateIndexBufferJob();

  function createBuffers$1(model, frameState) {
    var loadResources = model._loadResources;

    if (loadResources.pendingBufferLoads !== 0) {
      return;
    }

    var context = frameState.context;
    var vertexBuffersToCreate = loadResources.vertexBuffersToCreate;
    var indexBuffersToCreate = loadResources.indexBuffersToCreate;
    var i;

    if (model.asynchronous) {
      while (vertexBuffersToCreate.length > 0) {
        scratchVertexBufferJob.set(vertexBuffersToCreate.peek(), model, context);
        if (
          !frameState.jobScheduler.execute(scratchVertexBufferJob, JobType$1.BUFFER)
        ) {
          break;
        }
        vertexBuffersToCreate.dequeue();
      }

      while (indexBuffersToCreate.length > 0) {
        i = indexBuffersToCreate.peek();
        scratchIndexBufferJob.set(i.id, i.componentType, model, context);
        if (
          !frameState.jobScheduler.execute(scratchIndexBufferJob, JobType$1.BUFFER)
        ) {
          break;
        }
        indexBuffersToCreate.dequeue();
      }
    } else {
      while (vertexBuffersToCreate.length > 0) {
        createVertexBuffer$1(vertexBuffersToCreate.dequeue(), model, context);
      }

      while (indexBuffersToCreate.length > 0) {
        i = indexBuffersToCreate.dequeue();
        createIndexBuffer$1(i.id, i.componentType, model, context);
      }
    }
  }

  function getProgramForPrimitive(model, primitive) {
    var material = model._runtime.materialsById[primitive.material];
    if (!defined(material)) {
      return;
    }

    return material._program;
  }

  function modifyShaderForQuantizedAttributes$1(shader, programName, model) {
    var primitive;
    var primitives = model._programPrimitives[programName];

    // If no primitives were cached for this program, there's no need to modify the shader
    if (!defined(primitives)) {
      return shader;
    }

    var primitiveId;
    for (primitiveId in primitives) {
      if (primitives.hasOwnProperty(primitiveId)) {
        primitive = primitives[primitiveId];
        if (getProgramForPrimitive(model, primitive) === programName) {
          break;
        }
      }
    }

    // This is not needed after the program is processed, free the memory
    model._programPrimitives[programName] = undefined;

    var result;
    if (model.extensionsUsed.WEB3D_quantized_attributes) {
      result = ModelUtility.modifyShaderForQuantizedAttributes(
        model.gltf,
        primitive,
        shader
      );
      model._quantizedUniforms[programName] = result.uniforms;
    } else {
      var decodedData = model._decodedData[primitiveId];
      if (defined(decodedData)) {
        result = ModelUtility.modifyShaderForDracoQuantizedAttributes(
          model.gltf,
          primitive,
          shader,
          decodedData.attributes
        );
      } else {
        return shader;
      }
    }

    return result.shader;
  }

  function modifyShaderForColor(shader) {
    shader = ShaderSource.replaceMain(shader, "gltf_blend_main");
    shader +=
      "uniform vec4 gltf_color; \n" +
      "uniform float gltf_colorBlend; \n" +
      "void main() \n" +
      "{ \n" +
      "    gltf_blend_main(); \n" +
      "    gl_FragColor.rgb = mix(gl_FragColor.rgb, gltf_color.rgb, gltf_colorBlend); \n" +
      "    float highlight = ceil(gltf_colorBlend); \n" +
      "    gl_FragColor.rgb *= mix(gltf_color.rgb, vec3(1.0), highlight); \n" +
      "    gl_FragColor.a *= gltf_color.a; \n" +
      "} \n";

    return shader;
  }

  function modifyShader$1(shader, programName, callback) {
    if (defined(callback)) {
      shader = callback(shader, programName);
    }
    return shader;
  }

  var CreateProgramJob = function () {
    this.programToCreate = undefined;
    this.model = undefined;
    this.context = undefined;
  };

  CreateProgramJob.prototype.set = function (programToCreate, model, context) {
    this.programToCreate = programToCreate;
    this.model = model;
    this.context = context;
  };

  CreateProgramJob.prototype.execute = function () {
    createProgram$1(this.programToCreate, this.model, this.context);
  };

  ///////////////////////////////////////////////////////////////////////////

  // When building programs for the first time, do not include modifiers for clipping planes and color
  // since this is the version of the program that will be cached for use with other Models.
  function createProgram$1(programToCreate, model, context) {
    var programId = programToCreate.programId;
    var techniqueId = programToCreate.techniqueId;
    var program = model._sourcePrograms[programId];
    var shaders = model._rendererResources.sourceShaders;

    var vs = shaders[program.vertexShader];
    var fs = shaders[program.fragmentShader];

    var quantizedVertexShaders = model._quantizedVertexShaders;

    if (
      model.extensionsUsed.WEB3D_quantized_attributes ||
      model._dequantizeInShader
    ) {
      var quantizedVS = quantizedVertexShaders[programId];
      if (!defined(quantizedVS)) {
        quantizedVS = modifyShaderForQuantizedAttributes$1(vs, programId, model);
        quantizedVertexShaders[programId] = quantizedVS;
      }
      vs = quantizedVS;
    }

    var drawVS = modifyShader$1(vs, programId, model._vertexShaderLoaded);
    var drawFS = modifyShader$1(fs, programId, model._fragmentShaderLoaded);

    if (!defined(model._uniformMapLoaded)) {
      drawFS = "uniform vec4 czm_pickColor;\n" + drawFS;
    }

    var useIBL =
      model._imageBasedLightingFactor.x > 0.0 ||
      model._imageBasedLightingFactor.y > 0.0;
    if (useIBL) {
      drawFS = "#define USE_IBL_LIGHTING \n\n" + drawFS;
    }

    if (defined(model._lightColor)) {
      drawFS = "#define USE_CUSTOM_LIGHT_COLOR \n\n" + drawFS;
    }

    if (model._sourceVersion !== "2.0" || model._sourceKHRTechniquesWebGL) {
      drawFS = ShaderSource.replaceMain(drawFS, "non_gamma_corrected_main");
      drawFS =
        drawFS +
        "\n" +
        "void main() { \n" +
        "    non_gamma_corrected_main(); \n" +
        "    gl_FragColor = czm_gammaCorrect(gl_FragColor); \n" +
        "} \n";
    }

    if (OctahedralProjectedCubeMap.isSupported(context)) {
      var usesSH =
        defined(model._sphericalHarmonicCoefficients) ||
        model._useDefaultSphericalHarmonics;
      var usesSM =
        (defined(model._specularEnvironmentMapAtlas) &&
          model._specularEnvironmentMapAtlas.ready) ||
        model._useDefaultSpecularMaps;
      var addMatrix = usesSH || usesSM || useIBL;
      if (addMatrix) {
        drawFS = "uniform mat4 gltf_clippingPlanesMatrix; \n" + drawFS;
      }

      if (defined(model._sphericalHarmonicCoefficients)) {
        drawFS =
          "#define DIFFUSE_IBL \n" +
          "#define CUSTOM_SPHERICAL_HARMONICS \n" +
          "uniform vec3 gltf_sphericalHarmonicCoefficients[9]; \n" +
          drawFS;
      } else if (model._useDefaultSphericalHarmonics) {
        drawFS = "#define DIFFUSE_IBL \n" + drawFS;
      }

      if (
        defined(model._specularEnvironmentMapAtlas) &&
        model._specularEnvironmentMapAtlas.ready
      ) {
        drawFS =
          "#define SPECULAR_IBL \n" +
          "#define CUSTOM_SPECULAR_IBL \n" +
          "uniform sampler2D gltf_specularMap; \n" +
          "uniform vec2 gltf_specularMapSize; \n" +
          "uniform float gltf_maxSpecularLOD; \n" +
          drawFS;
      } else if (model._useDefaultSpecularMaps) {
        drawFS = "#define SPECULAR_IBL \n" + drawFS;
      }
    }

    if (defined(model._luminanceAtZenith)) {
      drawFS =
        "#define USE_SUN_LUMINANCE \n" +
        "uniform float gltf_luminanceAtZenith;\n" +
        drawFS;
    }

    createAttributesAndProgram(
      programId,
      techniqueId,
      drawFS,
      drawVS,
      model,
      context
    );
  }

  function recreateProgram(programToCreate, model, context) {
    var programId = programToCreate.programId;
    var techniqueId = programToCreate.techniqueId;
    var program = model._sourcePrograms[programId];
    var shaders = model._rendererResources.sourceShaders;

    var quantizedVertexShaders = model._quantizedVertexShaders;

    var clippingPlaneCollection = model.clippingPlanes;
    var addClippingPlaneCode = isClippingEnabled(model);

    var vs = shaders[program.vertexShader];
    var fs = shaders[program.fragmentShader];

    if (
      model.extensionsUsed.WEB3D_quantized_attributes ||
      model._dequantizeInShader
    ) {
      vs = quantizedVertexShaders[programId];
    }

    var finalFS = fs;
    if (isColorShadingEnabled(model)) {
      finalFS = Model._modifyShaderForColor(finalFS);
    }
    if (addClippingPlaneCode) {
      finalFS = modifyShaderForClippingPlanes(
        finalFS,
        clippingPlaneCollection,
        context
      );
    }

    var drawVS = modifyShader$1(vs, programId, model._vertexShaderLoaded);
    var drawFS = modifyShader$1(finalFS, programId, model._fragmentShaderLoaded);

    if (!defined(model._uniformMapLoaded)) {
      drawFS = "uniform vec4 czm_pickColor;\n" + drawFS;
    }

    var useIBL =
      model._imageBasedLightingFactor.x > 0.0 ||
      model._imageBasedLightingFactor.y > 0.0;
    if (useIBL) {
      drawFS = "#define USE_IBL_LIGHTING \n\n" + drawFS;
    }

    if (defined(model._lightColor)) {
      drawFS = "#define USE_CUSTOM_LIGHT_COLOR \n\n" + drawFS;
    }

    if (model._sourceVersion !== "2.0" || model._sourceKHRTechniquesWebGL) {
      drawFS = ShaderSource.replaceMain(drawFS, "non_gamma_corrected_main");
      drawFS =
        drawFS +
        "\n" +
        "void main() { \n" +
        "    non_gamma_corrected_main(); \n" +
        "    gl_FragColor = czm_gammaCorrect(gl_FragColor); \n" +
        "} \n";
    }

    if (OctahedralProjectedCubeMap.isSupported(context)) {
      var usesSH =
        defined(model._sphericalHarmonicCoefficients) ||
        model._useDefaultSphericalHarmonics;
      var usesSM =
        (defined(model._specularEnvironmentMapAtlas) &&
          model._specularEnvironmentMapAtlas.ready) ||
        model._useDefaultSpecularMaps;
      var addMatrix = !addClippingPlaneCode && (usesSH || usesSM || useIBL);
      if (addMatrix) {
        drawFS = "uniform mat4 gltf_clippingPlanesMatrix; \n" + drawFS;
      }

      if (defined(model._sphericalHarmonicCoefficients)) {
        drawFS =
          "#define DIFFUSE_IBL \n" +
          "#define CUSTOM_SPHERICAL_HARMONICS \n" +
          "uniform vec3 gltf_sphericalHarmonicCoefficients[9]; \n" +
          drawFS;
      } else if (model._useDefaultSphericalHarmonics) {
        drawFS = "#define DIFFUSE_IBL \n" + drawFS;
      }

      if (
        defined(model._specularEnvironmentMapAtlas) &&
        model._specularEnvironmentMapAtlas.ready
      ) {
        drawFS =
          "#define SPECULAR_IBL \n" +
          "#define CUSTOM_SPECULAR_IBL \n" +
          "uniform sampler2D gltf_specularMap; \n" +
          "uniform vec2 gltf_specularMapSize; \n" +
          "uniform float gltf_maxSpecularLOD; \n" +
          drawFS;
      } else if (model._useDefaultSpecularMaps) {
        drawFS = "#define SPECULAR_IBL \n" + drawFS;
      }
    }

    if (defined(model._luminanceAtZenith)) {
      drawFS =
        "#define USE_SUN_LUMINANCE \n" +
        "uniform float gltf_luminanceAtZenith;\n" +
        drawFS;
    }

    createAttributesAndProgram(
      programId,
      techniqueId,
      drawFS,
      drawVS,
      model,
      context
    );
  }

  function createAttributesAndProgram(
    programId,
    techniqueId,
    drawFS,
    drawVS,
    model,
    context
  ) {
    var technique = model._sourceTechniques[techniqueId];
    var attributeLocations = ModelUtility.createAttributeLocations(
      technique,
      model._precreatedAttributes
    );

    model._rendererResources.programs[programId] = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: drawVS,
      fragmentShaderSource: drawFS,
      attributeLocations: attributeLocations,
    });
  }

  var scratchCreateProgramJob = new CreateProgramJob();

  function createPrograms(model, frameState) {
    var loadResources = model._loadResources;
    var programsToCreate = loadResources.programsToCreate;

    if (loadResources.pendingShaderLoads !== 0) {
      return;
    }

    // PERFORMANCE_IDEA: this could be more fine-grained by looking
    // at the shader's bufferView's to determine the buffer dependencies.
    if (loadResources.pendingBufferLoads !== 0) {
      return;
    }

    var context = frameState.context;

    if (model.asynchronous) {
      while (programsToCreate.length > 0) {
        scratchCreateProgramJob.set(programsToCreate.peek(), model, context);
        if (
          !frameState.jobScheduler.execute(
            scratchCreateProgramJob,
            JobType$1.PROGRAM
          )
        ) {
          break;
        }
        programsToCreate.dequeue();
      }
    } else {
      // Create all loaded programs this frame
      while (programsToCreate.length > 0) {
        createProgram$1(programsToCreate.dequeue(), model, context);
      }
    }
  }

  function getOnImageCreatedFromTypedArray(loadResources, gltfTexture) {
    return function (image) {
      loadResources.texturesToCreate.enqueue({
        id: gltfTexture.id,
        image: image,
        bufferView: undefined,
      });

      --loadResources.pendingBufferViewToImage;
    };
  }

  function loadTexturesFromBufferViews(model) {
    var loadResources = model._loadResources;

    if (loadResources.pendingBufferLoads !== 0) {
      return;
    }

    while (loadResources.texturesToCreateFromBufferView.length > 0) {
      var gltfTexture = loadResources.texturesToCreateFromBufferView.dequeue();

      var gltf = model.gltf;
      var bufferView = gltf.bufferViews[gltfTexture.bufferView];
      var imageId = gltf.textures[gltfTexture.id].source;

      var onerror = ModelUtility.getFailedLoadFunction(
        model,
        "image",
        "id: " + gltfTexture.id + ", bufferView: " + gltfTexture.bufferView
      );

      if (gltfTexture.mimeType === "image/ktx") {
        loadKTX(loadResources.getBuffer(bufferView))
          .then(imageLoad(model, gltfTexture.id))
          .otherwise(onerror);
        ++model._loadResources.pendingTextureLoads;
      } else if (gltfTexture.mimeType === "image/crn") {
        loadCRN(loadResources.getBuffer(bufferView))
          .then(imageLoad(model, gltfTexture.id))
          .otherwise(onerror);
        ++model._loadResources.pendingTextureLoads;
      } else {
        var onload = getOnImageCreatedFromTypedArray(loadResources, gltfTexture);
        loadImageFromTypedArray({
          uint8Array: loadResources.getBuffer(bufferView),
          format: gltfTexture.mimeType,
          flipY: false,
        })
          .then(onload)
          .otherwise(onerror);
        ++loadResources.pendingBufferViewToImage;
      }
    }
  }

  function createSamplers(model) {
    var loadResources = model._loadResources;
    if (loadResources.createSamplers) {
      loadResources.createSamplers = false;

      var rendererSamplers = model._rendererResources.samplers;
      ForEach.sampler(model.gltf, function (sampler, samplerId) {
        rendererSamplers[samplerId] = new Sampler({
          wrapS: sampler.wrapS,
          wrapT: sampler.wrapT,
          minificationFilter: sampler.minFilter,
          magnificationFilter: sampler.magFilter,
        });
      });
    }
  }

  ///////////////////////////////////////////////////////////////////////////

  var CreateTextureJob = function () {
    this.gltfTexture = undefined;
    this.model = undefined;
    this.context = undefined;
  };

  CreateTextureJob.prototype.set = function (gltfTexture, model, context) {
    this.gltfTexture = gltfTexture;
    this.model = model;
    this.context = context;
  };

  CreateTextureJob.prototype.execute = function () {
    createTexture$3(this.gltfTexture, this.model, this.context);
  };

  ///////////////////////////////////////////////////////////////////////////

  function createTexture$3(gltfTexture, model, context) {
    var textures = model.gltf.textures;
    var texture = textures[gltfTexture.id];

    var rendererSamplers = model._rendererResources.samplers;
    var sampler = rendererSamplers[texture.sampler];
    if (!defined(sampler)) {
      sampler = new Sampler({
        wrapS: TextureWrap$1.REPEAT,
        wrapT: TextureWrap$1.REPEAT,
      });
    }

    var usesTextureTransform = false;
    var materials = model.gltf.materials;
    var materialsLength = materials.length;
    for (var i = 0; i < materialsLength; ++i) {
      var material = materials[i];
      if (
        defined(material.extensions) &&
        defined(material.extensions.KHR_techniques_webgl)
      ) {
        var values = material.extensions.KHR_techniques_webgl.values;
        for (var valueName in values) {
          if (
            values.hasOwnProperty(valueName) &&
            valueName.indexOf("Texture") !== -1
          ) {
            var value = values[valueName];
            if (
              value.index === gltfTexture.id &&
              defined(value.extensions) &&
              defined(value.extensions.KHR_texture_transform)
            ) {
              usesTextureTransform = true;
              break;
            }
          }
        }
      }
      if (usesTextureTransform) {
        break;
      }
    }

    var wrapS = sampler.wrapS;
    var wrapT = sampler.wrapT;
    var minFilter = sampler.minificationFilter;

    if (
      usesTextureTransform &&
      minFilter !== TextureMinificationFilter$1.LINEAR &&
      minFilter !== TextureMinificationFilter$1.NEAREST
    ) {
      if (
        minFilter === TextureMinificationFilter$1.NEAREST_MIPMAP_NEAREST ||
        minFilter === TextureMinificationFilter$1.NEAREST_MIPMAP_LINEAR
      ) {
        minFilter = TextureMinificationFilter$1.NEAREST;
      } else {
        minFilter = TextureMinificationFilter$1.LINEAR;
      }

      sampler = new Sampler({
        wrapS: sampler.wrapS,
        wrapT: sampler.wrapT,
        textureMinificationFilter: minFilter,
        textureMagnificationFilter: sampler.magnificationFilter,
      });
    }

    var internalFormat = gltfTexture.internalFormat;

    var mipmap =
      !(
        defined(internalFormat) && PixelFormat$1.isCompressedFormat(internalFormat)
      ) &&
      (minFilter === TextureMinificationFilter$1.NEAREST_MIPMAP_NEAREST ||
        minFilter === TextureMinificationFilter$1.NEAREST_MIPMAP_LINEAR ||
        minFilter === TextureMinificationFilter$1.LINEAR_MIPMAP_NEAREST ||
        minFilter === TextureMinificationFilter$1.LINEAR_MIPMAP_LINEAR);
    var requiresNpot =
      mipmap ||
      wrapS === TextureWrap$1.REPEAT ||
      wrapS === TextureWrap$1.MIRRORED_REPEAT ||
      wrapT === TextureWrap$1.REPEAT ||
      wrapT === TextureWrap$1.MIRRORED_REPEAT;

    var tx;
    var source = gltfTexture.image;

    if (defined(internalFormat)) {
      tx = new Texture({
        context: context,
        source: {
          arrayBufferView: gltfTexture.bufferView,
        },
        width: gltfTexture.width,
        height: gltfTexture.height,
        pixelFormat: internalFormat,
        sampler: sampler,
      });
    } else if (defined(source)) {
      var npot =
        !CesiumMath.isPowerOfTwo(source.width) ||
        !CesiumMath.isPowerOfTwo(source.height);

      if (requiresNpot && npot) {
        // WebGL requires power-of-two texture dimensions for mipmapping and REPEAT/MIRRORED_REPEAT wrap modes.
        var canvas = document.createElement("canvas");
        canvas.width = CesiumMath.nextPowerOfTwo(source.width);
        canvas.height = CesiumMath.nextPowerOfTwo(source.height);
        var canvasContext = canvas.getContext("2d");
        canvasContext.drawImage(
          source,
          0,
          0,
          source.width,
          source.height,
          0,
          0,
          canvas.width,
          canvas.height
        );
        source = canvas;
      }

      tx = new Texture({
        context: context,
        source: source,
        pixelFormat: texture.internalFormat,
        pixelDatatype: texture.type,
        sampler: sampler,
        flipY: false,
      });
      // GLTF_SPEC: Support TEXTURE_CUBE_MAP.  https://github.com/KhronosGroup/glTF/issues/40
      if (mipmap) {
        tx.generateMipmap();
      }
    }
    if (defined(tx)) {
      model._rendererResources.textures[gltfTexture.id] = tx;
      model._texturesByteLength += tx.sizeInBytes;
    }
  }

  var scratchCreateTextureJob = new CreateTextureJob();

  function createTextures(model, frameState) {
    var context = frameState.context;
    var texturesToCreate = model._loadResources.texturesToCreate;

    if (model.asynchronous) {
      while (texturesToCreate.length > 0) {
        scratchCreateTextureJob.set(texturesToCreate.peek(), model, context);
        if (
          !frameState.jobScheduler.execute(
            scratchCreateTextureJob,
            JobType$1.TEXTURE
          )
        ) {
          break;
        }
        texturesToCreate.dequeue();
      }
    } else {
      // Create all loaded textures this frame
      while (texturesToCreate.length > 0) {
        createTexture$3(texturesToCreate.dequeue(), model, context);
      }
    }
  }

  function getAttributeLocations$1(model, primitive) {
    var techniques = model._sourceTechniques;

    // Retrieve the compiled shader program to assign index values to attributes
    var attributeLocations = {};

    var location;
    var index;
    var material = model._runtime.materialsById[primitive.material];
    if (!defined(material)) {
      return attributeLocations;
    }

    var technique = techniques[material._technique];
    if (!defined(technique)) {
      return attributeLocations;
    }

    var attributes = technique.attributes;
    var program = model._rendererResources.programs[technique.program];
    var programVertexAttributes = program.vertexAttributes;
    var programAttributeLocations = program._attributeLocations;

    // Note: WebGL shader compiler may have optimized and removed some attributes from programVertexAttributes
    for (location in programVertexAttributes) {
      if (programVertexAttributes.hasOwnProperty(location)) {
        var attribute = attributes[location];
        if (defined(attribute)) {
          index = programAttributeLocations[location];
          attributeLocations[attribute.semantic] = index;
        }
      }
    }

    // Always add pre-created attributes.
    // Some pre-created attributes, like per-instance pickIds, may be compiled out of the draw program
    // but should be included in the list of attribute locations for the pick program.
    // This is safe to do since programVertexAttributes and programAttributeLocations are equivalent except
    // that programVertexAttributes optimizes out unused attributes.
    var precreatedAttributes = model._precreatedAttributes;
    if (defined(precreatedAttributes)) {
      for (location in precreatedAttributes) {
        if (precreatedAttributes.hasOwnProperty(location)) {
          index = programAttributeLocations[location];
          attributeLocations[location] = index;
        }
      }
    }

    return attributeLocations;
  }

  function createJoints(model, runtimeSkins) {
    var gltf = model.gltf;
    var skins = gltf.skins;
    var nodes = gltf.nodes;
    var runtimeNodes = model._runtime.nodes;

    var skinnedNodesIds = model._loadResources.skinnedNodesIds;
    var length = skinnedNodesIds.length;
    for (var j = 0; j < length; ++j) {
      var id = skinnedNodesIds[j];
      var skinnedNode = runtimeNodes[id];
      var node = nodes[id];

      var runtimeSkin = runtimeSkins[node.skin];
      skinnedNode.inverseBindMatrices = runtimeSkin.inverseBindMatrices;
      skinnedNode.bindShapeMatrix = runtimeSkin.bindShapeMatrix;

      var gltfJoints = skins[node.skin].joints;
      var jointsLength = gltfJoints.length;
      for (var i = 0; i < jointsLength; ++i) {
        var nodeId = gltfJoints[i];
        var jointNode = runtimeNodes[nodeId];
        skinnedNode.joints.push(jointNode);
      }
    }
  }

  function createSkins(model) {
    var loadResources = model._loadResources;

    if (loadResources.pendingBufferLoads !== 0) {
      return;
    }

    if (!loadResources.createSkins) {
      return;
    }
    loadResources.createSkins = false;

    var gltf = model.gltf;
    var accessors = gltf.accessors;
    var runtimeSkins = {};

    ForEach.skin(gltf, function (skin, id) {
      var accessor = accessors[skin.inverseBindMatrices];

      var bindShapeMatrix;
      if (!Matrix4.equals(skin.bindShapeMatrix, Matrix4.IDENTITY)) {
        bindShapeMatrix = Matrix4.clone(skin.bindShapeMatrix);
      }

      runtimeSkins[id] = {
        inverseBindMatrices: ModelAnimationCache.getSkinInverseBindMatrices(
          model,
          accessor
        ),
        bindShapeMatrix: bindShapeMatrix, // not used when undefined
      };
    });

    createJoints(model, runtimeSkins);
  }

  function getChannelEvaluator(model, runtimeNode, targetPath, spline) {
    return function (localAnimationTime) {
      if (defined(spline)) {
        localAnimationTime = model.clampAnimations
          ? spline.clampTime(localAnimationTime)
          : spline.wrapTime(localAnimationTime);
        runtimeNode[targetPath] = spline.evaluate(
          localAnimationTime,
          runtimeNode[targetPath]
        );
        runtimeNode.dirtyNumber = model._maxDirtyNumber;
      }
    };
  }

  function createRuntimeAnimations(model) {
    var loadResources = model._loadResources;

    if (!loadResources.finishedPendingBufferLoads()) {
      return;
    }

    if (!loadResources.createRuntimeAnimations) {
      return;
    }
    loadResources.createRuntimeAnimations = false;

    model._runtime.animations = [];

    var runtimeNodes = model._runtime.nodes;
    var accessors = model.gltf.accessors;

    ForEach.animation(model.gltf, function (animation, i) {
      var channels = animation.channels;
      var samplers = animation.samplers;

      // Find start and stop time for the entire animation
      var startTime = Number.MAX_VALUE;
      var stopTime = -Number.MAX_VALUE;

      var channelsLength = channels.length;
      var channelEvaluators = new Array(channelsLength);

      for (var j = 0; j < channelsLength; ++j) {
        var channel = channels[j];
        var target = channel.target;
        var path = target.path;
        var sampler = samplers[channel.sampler];
        var input = ModelAnimationCache.getAnimationParameterValues(
          model,
          accessors[sampler.input]
        );
        var output = ModelAnimationCache.getAnimationParameterValues(
          model,
          accessors[sampler.output]
        );

        startTime = Math.min(startTime, input[0]);
        stopTime = Math.max(stopTime, input[input.length - 1]);

        var spline = ModelAnimationCache.getAnimationSpline(
          model,
          i,
          animation,
          channel.sampler,
          sampler,
          input,
          path,
          output
        );

        channelEvaluators[j] = getChannelEvaluator(
          model,
          runtimeNodes[target.node],
          target.path,
          spline
        );
      }

      model._runtime.animations[i] = {
        name: animation.name,
        startTime: startTime,
        stopTime: stopTime,
        channelEvaluators: channelEvaluators,
      };
    });
  }

  function createVertexArrays(model, context) {
    var loadResources = model._loadResources;
    if (
      !loadResources.finishedBuffersCreation() ||
      !loadResources.finishedProgramCreation() ||
      !loadResources.createVertexArrays
    ) {
      return;
    }
    loadResources.createVertexArrays = false;

    var rendererBuffers = model._rendererResources.buffers;
    var rendererVertexArrays = model._rendererResources.vertexArrays;
    var gltf = model.gltf;
    var accessors = gltf.accessors;
    ForEach.mesh(gltf, function (mesh, meshId) {
      ForEach.meshPrimitive(mesh, function (primitive, primitiveId) {
        var attributes = [];
        var attributeLocation;
        var attributeLocations = getAttributeLocations$1(model, primitive);
        var decodedData =
          model._decodedData[meshId + ".primitive." + primitiveId];
        ForEach.meshPrimitiveAttribute(primitive, function (
          accessorId,
          attributeName
        ) {
          // Skip if the attribute is not used by the material, e.g., because the asset
          // was exported with an attribute that wasn't used and the asset wasn't optimized.
          attributeLocation = attributeLocations[attributeName];
          if (defined(attributeLocation)) {
            // Use attributes of previously decoded draco geometry
            if (defined(decodedData)) {
              var decodedAttributes = decodedData.attributes;
              if (decodedAttributes.hasOwnProperty(attributeName)) {
                var decodedAttribute = decodedAttributes[attributeName];
                attributes.push({
                  index: attributeLocation,
                  vertexBuffer: rendererBuffers[decodedAttribute.bufferView],
                  componentsPerAttribute: decodedAttribute.componentsPerAttribute,
                  componentDatatype: decodedAttribute.componentDatatype,
                  normalize: decodedAttribute.normalized,
                  offsetInBytes: decodedAttribute.byteOffset,
                  strideInBytes: decodedAttribute.byteStride,
                });

                return;
              }
            }

            var a = accessors[accessorId];
            var normalize = defined(a.normalized) && a.normalized;
            attributes.push({
              index: attributeLocation,
              vertexBuffer: rendererBuffers[a.bufferView],
              componentsPerAttribute: numberOfComponentsForType(a.type),
              componentDatatype: a.componentType,
              normalize: normalize,
              offsetInBytes: a.byteOffset,
              strideInBytes: getAccessorByteStride(gltf, a),
            });
          }
        });

        // Add pre-created attributes
        var attribute;
        var attributeName;
        var precreatedAttributes = model._precreatedAttributes;
        if (defined(precreatedAttributes)) {
          for (attributeName in precreatedAttributes) {
            if (precreatedAttributes.hasOwnProperty(attributeName)) {
              attributeLocation = attributeLocations[attributeName];
              if (defined(attributeLocation)) {
                attribute = precreatedAttributes[attributeName];
                attribute.index = attributeLocation;
                attributes.push(attribute);
              }
            }
          }
        }

        var indexBuffer;
        if (defined(primitive.indices)) {
          var accessor = accessors[primitive.indices];
          var bufferView = accessor.bufferView;

          // Use buffer of previously decoded draco geometry
          if (defined(decodedData)) {
            bufferView = decodedData.bufferView;
          }

          indexBuffer = rendererBuffers[bufferView];
        }
        rendererVertexArrays[
          meshId + ".primitive." + primitiveId
        ] = new VertexArray({
          context: context,
          attributes: attributes,
          indexBuffer: indexBuffer,
        });
      });
    });
  }

  function createRenderStates$3(model) {
    var loadResources = model._loadResources;
    if (loadResources.createRenderStates) {
      loadResources.createRenderStates = false;

      ForEach.material(model.gltf, function (material, materialId) {
        createRenderStateForMaterial(model, material, materialId);
      });
    }
  }

  function createRenderStateForMaterial(model, material, materialId) {
    var rendererRenderStates = model._rendererResources.renderStates;

    var blendEquationSeparate = [
      WebGLConstants$1.FUNC_ADD,
      WebGLConstants$1.FUNC_ADD,
    ];
    var blendFuncSeparate = [
      WebGLConstants$1.ONE,
      WebGLConstants$1.ONE_MINUS_SRC_ALPHA,
      WebGLConstants$1.ONE,
      WebGLConstants$1.ONE_MINUS_SRC_ALPHA,
    ];

    if (defined(material.extensions) && defined(material.extensions.KHR_blend)) {
      blendEquationSeparate = material.extensions.KHR_blend.blendEquation;
      blendFuncSeparate = material.extensions.KHR_blend.blendFactors;
    }

    var enableCulling = !material.doubleSided;
    var blendingEnabled = material.alphaMode === "BLEND";
    rendererRenderStates[materialId] = RenderState.fromCache({
      cull: {
        enabled: enableCulling,
      },
      depthTest: {
        enabled: true,
        func: DepthFunction$1.LESS_OR_EQUAL,
      },
      depthMask: !blendingEnabled,
      blending: {
        enabled: blendingEnabled,
        equationRgb: blendEquationSeparate[0],
        equationAlpha: blendEquationSeparate[1],
        functionSourceRgb: blendFuncSeparate[0],
        functionDestinationRgb: blendFuncSeparate[1],
        functionSourceAlpha: blendFuncSeparate[2],
        functionDestinationAlpha: blendFuncSeparate[3],
      },
    });
  }

  ///////////////////////////////////////////////////////////////////////////

  var gltfUniformsFromNode = {
    MODEL: function (uniformState, model, runtimeNode) {
      return function () {
        return runtimeNode.computedMatrix;
      };
    },
    VIEW: function (uniformState, model, runtimeNode) {
      return function () {
        return uniformState.view;
      };
    },
    PROJECTION: function (uniformState, model, runtimeNode) {
      return function () {
        return uniformState.projection;
      };
    },
    MODELVIEW: function (uniformState, model, runtimeNode) {
      var mv = new Matrix4();
      return function () {
        return Matrix4.multiplyTransformation(
          uniformState.view,
          runtimeNode.computedMatrix,
          mv
        );
      };
    },
    CESIUM_RTC_MODELVIEW: function (uniformState, model, runtimeNode) {
      // CESIUM_RTC extension
      var mvRtc = new Matrix4();
      return function () {
        Matrix4.multiplyTransformation(
          uniformState.view,
          runtimeNode.computedMatrix,
          mvRtc
        );
        return Matrix4.setTranslation(mvRtc, model._rtcCenterEye, mvRtc);
      };
    },
    MODELVIEWPROJECTION: function (uniformState, model, runtimeNode) {
      var mvp = new Matrix4();
      return function () {
        Matrix4.multiplyTransformation(
          uniformState.view,
          runtimeNode.computedMatrix,
          mvp
        );
        return Matrix4.multiply(uniformState._projection, mvp, mvp);
      };
    },
    MODELINVERSE: function (uniformState, model, runtimeNode) {
      var mInverse = new Matrix4();
      return function () {
        return Matrix4.inverse(runtimeNode.computedMatrix, mInverse);
      };
    },
    VIEWINVERSE: function (uniformState, model) {
      return function () {
        return uniformState.inverseView;
      };
    },
    PROJECTIONINVERSE: function (uniformState, model, runtimeNode) {
      return function () {
        return uniformState.inverseProjection;
      };
    },
    MODELVIEWINVERSE: function (uniformState, model, runtimeNode) {
      var mv = new Matrix4();
      var mvInverse = new Matrix4();
      return function () {
        Matrix4.multiplyTransformation(
          uniformState.view,
          runtimeNode.computedMatrix,
          mv
        );
        return Matrix4.inverse(mv, mvInverse);
      };
    },
    MODELVIEWPROJECTIONINVERSE: function (uniformState, model, runtimeNode) {
      var mvp = new Matrix4();
      var mvpInverse = new Matrix4();
      return function () {
        Matrix4.multiplyTransformation(
          uniformState.view,
          runtimeNode.computedMatrix,
          mvp
        );
        Matrix4.multiply(uniformState._projection, mvp, mvp);
        return Matrix4.inverse(mvp, mvpInverse);
      };
    },
    MODELINVERSETRANSPOSE: function (uniformState, model, runtimeNode) {
      var mInverse = new Matrix4();
      var mInverseTranspose = new Matrix3();
      return function () {
        Matrix4.inverse(runtimeNode.computedMatrix, mInverse);
        Matrix4.getMatrix3(mInverse, mInverseTranspose);
        return Matrix3.transpose(mInverseTranspose, mInverseTranspose);
      };
    },
    MODELVIEWINVERSETRANSPOSE: function (uniformState, model, runtimeNode) {
      var mv = new Matrix4();
      var mvInverse = new Matrix4();
      var mvInverseTranspose = new Matrix3();
      return function () {
        Matrix4.multiplyTransformation(
          uniformState.view,
          runtimeNode.computedMatrix,
          mv
        );
        Matrix4.inverse(mv, mvInverse);
        Matrix4.getMatrix3(mvInverse, mvInverseTranspose);
        return Matrix3.transpose(mvInverseTranspose, mvInverseTranspose);
      };
    },
    VIEWPORT: function (uniformState, model, runtimeNode) {
      return function () {
        return uniformState.viewportCartesian4;
      };
    },
  };

  function getUniformFunctionFromSource(source, model, semantic, uniformState) {
    var runtimeNode = model._runtime.nodes[source];
    return gltfUniformsFromNode[semantic](uniformState, model, runtimeNode);
  }

  function createUniformsForMaterial(
    model,
    material,
    technique,
    instanceValues,
    context,
    textures,
    defaultTexture
  ) {
    var uniformMap = {};
    var uniformValues = {};
    var jointMatrixUniformName;
    var morphWeightsUniformName;

    ForEach.techniqueUniform(technique, function (uniform, uniformName) {
      // GLTF_SPEC: This does not take into account uniform arrays,
      // indicated by uniforms with a count property.
      //
      // https://github.com/KhronosGroup/glTF/issues/258

      // GLTF_SPEC: In this implementation, material parameters with a
      // semantic or targeted via a source (for animation) are not
      // targetable for material animations.  Is this too strict?
      //
      // https://github.com/KhronosGroup/glTF/issues/142

      var uv;
      if (defined(instanceValues) && defined(instanceValues[uniformName])) {
        // Parameter overrides by the instance technique
        uv = ModelUtility.createUniformFunction(
          uniform.type,
          instanceValues[uniformName],
          textures,
          defaultTexture
        );
        uniformMap[uniformName] = uv.func;
        uniformValues[uniformName] = uv;
      } else if (defined(uniform.node)) {
        uniformMap[uniformName] = getUniformFunctionFromSource(
          uniform.node,
          model,
          uniform.semantic,
          context.uniformState
        );
      } else if (defined(uniform.semantic)) {
        if (uniform.semantic === "JOINTMATRIX") {
          jointMatrixUniformName = uniformName;
        } else if (uniform.semantic === "MORPHWEIGHTS") {
          morphWeightsUniformName = uniformName;
        } else if (uniform.semantic === "ALPHACUTOFF") {
          // The material's alphaCutoff value uses a uniform with semantic ALPHACUTOFF.
          // A uniform with this semantic will ignore the instance or default values.
          var alphaMode = material.alphaMode;
          if (defined(alphaMode) && alphaMode === "MASK") {
            var alphaCutoffValue = defaultValue(material.alphaCutoff, 0.5);
            uv = ModelUtility.createUniformFunction(
              uniform.type,
              alphaCutoffValue,
              textures,
              defaultTexture
            );
            uniformMap[uniformName] = uv.func;
            uniformValues[uniformName] = uv;
          }
        } else {
          // Map glTF semantic to Cesium automatic uniform
          uniformMap[uniformName] = ModelUtility.getGltfSemanticUniforms()[
            uniform.semantic
          ](context.uniformState, model);
        }
      } else if (defined(uniform.value)) {
        // Technique value that isn't overridden by a material
        var uv2 = ModelUtility.createUniformFunction(
          uniform.type,
          uniform.value,
          textures,
          defaultTexture
        );
        uniformMap[uniformName] = uv2.func;
        uniformValues[uniformName] = uv2;
      }
    });

    return {
      map: uniformMap,
      values: uniformValues,
      jointMatrixUniformName: jointMatrixUniformName,
      morphWeightsUniformName: morphWeightsUniformName,
    };
  }

  function createUniformMaps(model, context) {
    var loadResources = model._loadResources;

    if (!loadResources.finishedProgramCreation()) {
      return;
    }

    if (!loadResources.createUniformMaps) {
      return;
    }
    loadResources.createUniformMaps = false;

    var gltf = model.gltf;
    var techniques = model._sourceTechniques;
    var uniformMaps = model._uniformMaps;

    var textures = model._rendererResources.textures;
    var defaultTexture = model._defaultTexture;

    ForEach.material(gltf, function (material, materialId) {
      var modelMaterial = model._runtime.materialsById[materialId];
      var technique = techniques[modelMaterial._technique];
      var instanceValues = modelMaterial._values;

      var uniforms = createUniformsForMaterial(
        model,
        material,
        technique,
        instanceValues,
        context,
        textures,
        defaultTexture
      );

      var u = uniformMaps[materialId];
      u.uniformMap = uniforms.map; // uniform name -> function for the renderer
      u.values = uniforms.values; // material parameter name -> ModelMaterial for modifying the parameter at runtime
      u.jointMatrixUniformName = uniforms.jointMatrixUniformName;
      u.morphWeightsUniformName = uniforms.morphWeightsUniformName;

      if (defined(technique.attributes.a_outlineCoordinates)) {
        var outlineTexture = ModelOutlineLoader.createTexture(model, context);
        u.uniformMap.u_outlineTexture = function () {
          return outlineTexture;
        };
      }
    });
  }

  function createUniformsForDracoQuantizedAttributes(decodedData) {
    return ModelUtility.createUniformsForDracoQuantizedAttributes(
      decodedData.attributes
    );
  }

  function createUniformsForQuantizedAttributes$1(model, primitive) {
    var programId = getProgramForPrimitive(model, primitive);
    var quantizedUniforms = model._quantizedUniforms[programId];
    return ModelUtility.createUniformsForQuantizedAttributes(
      model.gltf,
      primitive,
      quantizedUniforms
    );
  }

  function createPickColorFunction(color) {
    return function () {
      return color;
    };
  }

  function createJointMatricesFunction(runtimeNode) {
    return function () {
      return runtimeNode.computedJointMatrices;
    };
  }

  function createMorphWeightsFunction(runtimeNode) {
    return function () {
      return runtimeNode.weights;
    };
  }

  function createSilhouetteColorFunction(model) {
    return function () {
      return model.silhouetteColor;
    };
  }

  function createSilhouetteSizeFunction(model) {
    return function () {
      return model.silhouetteSize;
    };
  }

  function createColorFunction(model) {
    return function () {
      return model.color;
    };
  }

  var scratchClippingPlaneMatrix = new Matrix4();
  function createClippingPlanesMatrixFunction(model) {
    return function () {
      var clippingPlanes = model.clippingPlanes;
      if (
        !defined(clippingPlanes) &&
        !defined(model._sphericalHarmonicCoefficients) &&
        !defined(model._specularEnvironmentMaps)
      ) {
        return Matrix4.IDENTITY;
      }
      var modelMatrix = defined(clippingPlanes)
        ? clippingPlanes.modelMatrix
        : Matrix4.IDENTITY;
      return Matrix4.multiply(
        model._clippingPlaneModelViewMatrix,
        modelMatrix,
        scratchClippingPlaneMatrix
      );
    };
  }

  function createClippingPlanesFunction(model) {
    return function () {
      var clippingPlanes = model.clippingPlanes;
      return !defined(clippingPlanes) || !clippingPlanes.enabled
        ? model._defaultTexture
        : clippingPlanes.texture;
    };
  }

  function createClippingPlanesEdgeStyleFunction(model) {
    return function () {
      var clippingPlanes = model.clippingPlanes;
      if (!defined(clippingPlanes)) {
        return Color.WHITE.withAlpha(0.0);
      }

      var style = Color.clone(clippingPlanes.edgeColor);
      style.alpha = clippingPlanes.edgeWidth;
      return style;
    };
  }

  function createColorBlendFunction(model) {
    return function () {
      return ColorBlendMode$1.getColorBlend(
        model.colorBlendMode,
        model.colorBlendAmount
      );
    };
  }

  function createIBLFactorFunction(model) {
    return function () {
      return model._imageBasedLightingFactor;
    };
  }

  function createLightColorFunction(model) {
    return function () {
      return model._lightColor;
    };
  }

  function createLuminanceAtZenithFunction(model) {
    return function () {
      return model.luminanceAtZenith;
    };
  }

  function createSphericalHarmonicCoefficientsFunction(model) {
    return function () {
      return model._sphericalHarmonicCoefficients;
    };
  }

  function createSpecularEnvironmentMapFunction(model) {
    return function () {
      return model._specularEnvironmentMapAtlas.texture;
    };
  }

  function createSpecularEnvironmentMapSizeFunction(model) {
    return function () {
      return model._specularEnvironmentMapAtlas.texture.dimensions;
    };
  }

  function createSpecularEnvironmentMapLOD(model) {
    return function () {
      return model._specularEnvironmentMapAtlas.maximumMipmapLevel;
    };
  }

  function triangleCountFromPrimitiveIndices$1(primitive, indicesCount) {
    switch (primitive.mode) {
      case PrimitiveType$1.TRIANGLES:
        return indicesCount / 3;
      case PrimitiveType$1.TRIANGLE_STRIP:
      case PrimitiveType$1.TRIANGLE_FAN:
        return Math.max(indicesCount - 2, 0);
      default:
        return 0;
    }
  }

  function createCommand(model, gltfNode, runtimeNode, context, scene3DOnly) {
    var nodeCommands = model._nodeCommands;
    var pickIds = model._pickIds;
    var allowPicking = model.allowPicking;
    var runtimeMeshesByName = model._runtime.meshesByName;

    var resources = model._rendererResources;
    var rendererVertexArrays = resources.vertexArrays;
    var rendererPrograms = resources.programs;
    var rendererRenderStates = resources.renderStates;
    var uniformMaps = model._uniformMaps;

    var gltf = model.gltf;
    var accessors = gltf.accessors;
    var gltfMeshes = gltf.meshes;

    var id = gltfNode.mesh;
    var mesh = gltfMeshes[id];

    var primitives = mesh.primitives;
    var length = primitives.length;

    // The glTF node hierarchy is a DAG so a node can have more than one
    // parent, so a node may already have commands.  If so, append more
    // since they will have a different model matrix.

    for (var i = 0; i < length; ++i) {
      var primitive = primitives[i];
      var ix = accessors[primitive.indices];
      var material = model._runtime.materialsById[primitive.material];
      var programId = material._program;
      var decodedData = model._decodedData[id + ".primitive." + i];

      var boundingSphere;
      var positionAccessor = primitive.attributes.POSITION;
      if (defined(positionAccessor)) {
        var minMax = ModelUtility.getAccessorMinMax(gltf, positionAccessor);
        boundingSphere = BoundingSphere.fromCornerPoints(
          Cartesian3.fromArray(minMax.min),
          Cartesian3.fromArray(minMax.max)
        );
      }

      var vertexArray = rendererVertexArrays[id + ".primitive." + i];
      var offset;
      var count;

      // Use indices of the previously decoded Draco geometry.
      if (defined(decodedData)) {
        count = decodedData.numberOfIndices;
        offset = 0;
      } else if (defined(ix)) {
        count = ix.count;
        offset = ix.byteOffset / IndexDatatype$1.getSizeInBytes(ix.componentType); // glTF has offset in bytes.  Cesium has offsets in indices
      } else {
        var positions = accessors[primitive.attributes.POSITION];
        count = positions.count;
        offset = 0;
      }

      // Update model triangle count using number of indices
      model._trianglesLength += triangleCountFromPrimitiveIndices$1(
        primitive,
        count
      );

      var um = uniformMaps[primitive.material];
      var uniformMap = um.uniformMap;
      if (defined(um.jointMatrixUniformName)) {
        var jointUniformMap = {};
        jointUniformMap[um.jointMatrixUniformName] = createJointMatricesFunction(
          runtimeNode
        );

        uniformMap = combine(uniformMap, jointUniformMap);
      }
      if (defined(um.morphWeightsUniformName)) {
        var morphWeightsUniformMap = {};
        morphWeightsUniformMap[
          um.morphWeightsUniformName
        ] = createMorphWeightsFunction(runtimeNode);

        uniformMap = combine(uniformMap, morphWeightsUniformMap);
      }

      uniformMap = combine(uniformMap, {
        gltf_color: createColorFunction(model),
        gltf_colorBlend: createColorBlendFunction(model),
        gltf_clippingPlanes: createClippingPlanesFunction(model),
        gltf_clippingPlanesEdgeStyle: createClippingPlanesEdgeStyleFunction(
          model
        ),
        gltf_clippingPlanesMatrix: createClippingPlanesMatrixFunction(model),
        gltf_iblFactor: createIBLFactorFunction(model),
        gltf_lightColor: createLightColorFunction(model),
        gltf_sphericalHarmonicCoefficients: createSphericalHarmonicCoefficientsFunction(
          model
        ),
        gltf_specularMap: createSpecularEnvironmentMapFunction(model),
        gltf_specularMapSize: createSpecularEnvironmentMapSizeFunction(model),
        gltf_maxSpecularLOD: createSpecularEnvironmentMapLOD(model),
        gltf_luminanceAtZenith: createLuminanceAtZenithFunction(model),
      });

      // Allow callback to modify the uniformMap
      if (defined(model._uniformMapLoaded)) {
        uniformMap = model._uniformMapLoaded(uniformMap, programId, runtimeNode);
      }

      // Add uniforms for decoding quantized attributes if used
      var quantizedUniformMap = {};
      if (model.extensionsUsed.WEB3D_quantized_attributes) {
        quantizedUniformMap = createUniformsForQuantizedAttributes$1(
          model,
          primitive
        );
      } else if (model._dequantizeInShader && defined(decodedData)) {
        quantizedUniformMap = createUniformsForDracoQuantizedAttributes(
          decodedData
        );
      }
      uniformMap = combine(uniformMap, quantizedUniformMap);

      var rs = rendererRenderStates[primitive.material];
      var isTranslucent = rs.blending.enabled;

      var owner = model._pickObject;
      if (!defined(owner)) {
        owner = {
          primitive: model,
          id: model.id,
          node: runtimeNode.publicNode,
          mesh: runtimeMeshesByName[mesh.name],
        };
      }

      var castShadows = ShadowMode$1.castShadows(model._shadows);
      var receiveShadows = ShadowMode$1.receiveShadows(model._shadows);

      var pickId;
      if (allowPicking && !defined(model._uniformMapLoaded)) {
        pickId = context.createPickId(owner);
        pickIds.push(pickId);
        var pickUniforms = {
          czm_pickColor: createPickColorFunction(pickId.color),
        };
        uniformMap = combine(uniformMap, pickUniforms);
      }

      if (allowPicking) {
        if (defined(model._pickIdLoaded) && defined(model._uniformMapLoaded)) {
          pickId = model._pickIdLoaded();
        } else {
          pickId = "czm_pickColor";
        }
      }

      var command = new DrawCommand({
        boundingVolume: new BoundingSphere(), // updated in update()
        cull: model.cull,
        modelMatrix: new Matrix4(), // computed in update()
        primitiveType: primitive.mode,
        vertexArray: vertexArray,
        count: count,
        offset: offset,
        shaderProgram: rendererPrograms[programId],
        castShadows: castShadows,
        receiveShadows: receiveShadows,
        uniformMap: uniformMap,
        renderState: rs,
        owner: owner,
        pass: isTranslucent ? Pass$1.TRANSLUCENT : model.opaquePass,
        pickId: pickId,
      });

      var command2D;
      if (!scene3DOnly) {
        command2D = DrawCommand.shallowClone(command);
        command2D.boundingVolume = new BoundingSphere(); // updated in update()
        command2D.modelMatrix = new Matrix4(); // updated in update()
      }

      var nodeCommand = {
        show: true,
        boundingSphere: boundingSphere,
        command: command,
        command2D: command2D,
        // Generated on demand when silhouette size is greater than 0.0 and silhouette alpha is greater than 0.0
        silhouetteModelCommand: undefined,
        silhouetteModelCommand2D: undefined,
        silhouetteColorCommand: undefined,
        silhouetteColorCommand2D: undefined,
        // Generated on demand when color alpha is less than 1.0
        translucentCommand: undefined,
        translucentCommand2D: undefined,
        // Generated on demand when back face culling is false
        disableCullingCommand: undefined,
        disableCullingCommand2D: undefined,
        // For updating node commands on shader reconstruction
        programId: programId,
      };
      runtimeNode.commands.push(nodeCommand);
      nodeCommands.push(nodeCommand);
    }
  }

  function createRuntimeNodes$1(model, context, scene3DOnly) {
    var loadResources = model._loadResources;

    if (!loadResources.finishedEverythingButTextureCreation()) {
      return;
    }

    if (!loadResources.createRuntimeNodes) {
      return;
    }
    loadResources.createRuntimeNodes = false;

    var rootNodes = [];
    var runtimeNodes = model._runtime.nodes;

    var gltf = model.gltf;
    var nodes = gltf.nodes;

    var scene = gltf.scenes[gltf.scene];
    var sceneNodes = scene.nodes;
    var length = sceneNodes.length;

    var stack = [];
    var seen = {};

    for (var i = 0; i < length; ++i) {
      stack.push({
        parentRuntimeNode: undefined,
        gltfNode: nodes[sceneNodes[i]],
        id: sceneNodes[i],
      });

      while (stack.length > 0) {
        var n = stack.pop();
        seen[n.id] = true;
        var parentRuntimeNode = n.parentRuntimeNode;
        var gltfNode = n.gltfNode;

        // Node hierarchy is a DAG so a node can have more than one parent so it may already exist
        var runtimeNode = runtimeNodes[n.id];
        if (runtimeNode.parents.length === 0) {
          if (defined(gltfNode.matrix)) {
            runtimeNode.matrix = Matrix4.fromColumnMajorArray(gltfNode.matrix);
          } else {
            // TRS converted to Cesium types
            var rotation = gltfNode.rotation;
            runtimeNode.translation = Cartesian3.fromArray(gltfNode.translation);
            runtimeNode.rotation = Quaternion.unpack(rotation);
            runtimeNode.scale = Cartesian3.fromArray(gltfNode.scale);
          }
        }

        if (defined(parentRuntimeNode)) {
          parentRuntimeNode.children.push(runtimeNode);
          runtimeNode.parents.push(parentRuntimeNode);
        } else {
          rootNodes.push(runtimeNode);
        }

        if (defined(gltfNode.mesh)) {
          createCommand(model, gltfNode, runtimeNode, context, scene3DOnly);
        }

        var children = gltfNode.children;
        if (defined(children)) {
          var childrenLength = children.length;
          for (var j = 0; j < childrenLength; j++) {
            var childId = children[j];
            if (!seen[childId]) {
              stack.push({
                parentRuntimeNode: runtimeNode,
                gltfNode: nodes[childId],
                id: children[j],
              });
            }
          }
        }
      }
    }

    model._runtime.rootNodes = rootNodes;
    model._runtime.nodes = runtimeNodes;
  }

  function getGeometryByteLength(buffers) {
    var memory = 0;
    for (var id in buffers) {
      if (buffers.hasOwnProperty(id)) {
        memory += buffers[id].sizeInBytes;
      }
    }
    return memory;
  }

  function getTexturesByteLength(textures) {
    var memory = 0;
    for (var id in textures) {
      if (textures.hasOwnProperty(id)) {
        memory += textures[id].sizeInBytes;
      }
    }
    return memory;
  }

  function createResources$1(model, frameState) {
    var context = frameState.context;
    var scene3DOnly = frameState.scene3DOnly;
    var quantizedVertexShaders = model._quantizedVertexShaders;
    var techniques = model._sourceTechniques;
    var programs = model._sourcePrograms;

    var resources = model._rendererResources;
    var shaders = resources.sourceShaders;
    if (model._loadRendererResourcesFromCache) {
      shaders = resources.sourceShaders =
        model._cachedRendererResources.sourceShaders;
    }

    for (var techniqueId in techniques) {
      if (techniques.hasOwnProperty(techniqueId)) {
        var programId = techniques[techniqueId].program;
        var program = programs[programId];
        var shader = shaders[program.vertexShader];

        ModelUtility.checkSupportedGlExtensions(program.glExtensions, context);

        if (
          model.extensionsUsed.WEB3D_quantized_attributes ||
          model._dequantizeInShader
        ) {
          var quantizedVS = quantizedVertexShaders[programId];
          if (!defined(quantizedVS)) {
            quantizedVS = modifyShaderForQuantizedAttributes$1(
              shader,
              programId,
              model
            );
            quantizedVertexShaders[programId] = quantizedVS;
          }
          shader = quantizedVS;
        }

        shader = modifyShader$1(shader, programId, model._vertexShaderLoaded);
      }
    }

    if (model._loadRendererResourcesFromCache) {
      var cachedResources = model._cachedRendererResources;

      resources.buffers = cachedResources.buffers;
      resources.vertexArrays = cachedResources.vertexArrays;
      resources.programs = cachedResources.programs;
      resources.silhouettePrograms = cachedResources.silhouettePrograms;
      resources.textures = cachedResources.textures;
      resources.samplers = cachedResources.samplers;
      resources.renderStates = cachedResources.renderStates;

      // Vertex arrays are unique to this model, create instead of using the cache.
      if (defined(model._precreatedAttributes)) {
        createVertexArrays(model, context);
      }

      model._cachedGeometryByteLength += getGeometryByteLength(
        cachedResources.buffers
      );
      model._cachedTexturesByteLength += getTexturesByteLength(
        cachedResources.textures
      );
    } else {
      createBuffers$1(model, frameState); // using glTF bufferViews
      createPrograms(model, frameState);
      createSamplers(model);
      loadTexturesFromBufferViews(model);
      createTextures(model, frameState);
    }

    createSkins(model);
    createRuntimeAnimations(model);

    if (!model._loadRendererResourcesFromCache) {
      createVertexArrays(model, context); // using glTF meshes
      createRenderStates$3(model); // using glTF materials/techniques/states
      // Long-term, we might not cache render states if they could change
      // due to an animation, e.g., a uniform going from opaque to transparent.
      // Could use copy-on-write if it is worth it.  Probably overkill.
    }

    createUniformMaps(model, context); // using glTF materials/techniques
    createRuntimeNodes$1(model, context, scene3DOnly); // using glTF scene
  }

  ///////////////////////////////////////////////////////////////////////////

  function getNodeMatrix(node, result) {
    var publicNode = node.publicNode;
    var publicMatrix = publicNode.matrix;

    if (publicNode.useMatrix && defined(publicMatrix)) {
      // Public matrix overrides original glTF matrix and glTF animations
      Matrix4.clone(publicMatrix, result);
    } else if (defined(node.matrix)) {
      Matrix4.clone(node.matrix, result);
    } else {
      Matrix4.fromTranslationQuaternionRotationScale(
        node.translation,
        node.rotation,
        node.scale,
        result
      );
      // Keep matrix returned by the node in-sync if the node is targeted by an animation.  Only TRS nodes can be targeted.
      publicNode.setMatrix(result);
    }
  }

  var scratchNodeStack = [];
  var scratchComputedTranslation$1 = new Cartesian4();
  var scratchComputedMatrixIn2D$1 = new Matrix4();

  function updateNodeHierarchyModelMatrix(
    model,
    modelTransformChanged,
    justLoaded,
    projection
  ) {
    var maxDirtyNumber = model._maxDirtyNumber;

    var rootNodes = model._runtime.rootNodes;
    var length = rootNodes.length;

    var nodeStack = scratchNodeStack;
    var computedModelMatrix = model._computedModelMatrix;

    if (model._mode !== SceneMode$1.SCENE3D && !model._ignoreCommands) {
      var translation = Matrix4.getColumn(
        computedModelMatrix,
        3,
        scratchComputedTranslation$1
      );
      if (!Cartesian4.equals(translation, Cartesian4.UNIT_W)) {
        computedModelMatrix = Transforms.basisTo2D(
          projection,
          computedModelMatrix,
          scratchComputedMatrixIn2D$1
        );
        model._rtcCenter = model._rtcCenter3D;
      } else {
        var center = model.boundingSphere.center;
        var to2D = Transforms.wgs84To2DModelMatrix(
          projection,
          center,
          scratchComputedMatrixIn2D$1
        );
        computedModelMatrix = Matrix4.multiply(
          to2D,
          computedModelMatrix,
          scratchComputedMatrixIn2D$1
        );

        if (defined(model._rtcCenter)) {
          Matrix4.setTranslation(
            computedModelMatrix,
            Cartesian4.UNIT_W,
            computedModelMatrix
          );
          model._rtcCenter = model._rtcCenter2D;
        }
      }
    }

    for (var i = 0; i < length; ++i) {
      var n = rootNodes[i];

      getNodeMatrix(n, n.transformToRoot);
      nodeStack.push(n);

      while (nodeStack.length > 0) {
        n = nodeStack.pop();
        var transformToRoot = n.transformToRoot;
        var commands = n.commands;

        if (
          n.dirtyNumber === maxDirtyNumber ||
          modelTransformChanged ||
          justLoaded
        ) {
          var nodeMatrix = Matrix4.multiplyTransformation(
            computedModelMatrix,
            transformToRoot,
            n.computedMatrix
          );
          var commandsLength = commands.length;
          if (commandsLength > 0) {
            // Node has meshes, which has primitives.  Update their commands.
            for (var j = 0; j < commandsLength; ++j) {
              var primitiveCommand = commands[j];
              var command = primitiveCommand.command;
              Matrix4.clone(nodeMatrix, command.modelMatrix);

              // PERFORMANCE_IDEA: Can use transformWithoutScale if no node up to the root has scale (including animation)
              BoundingSphere.transform(
                primitiveCommand.boundingSphere,
                command.modelMatrix,
                command.boundingVolume
              );

              if (defined(model._rtcCenter)) {
                Cartesian3.add(
                  model._rtcCenter,
                  command.boundingVolume.center,
                  command.boundingVolume.center
                );
              }

              // If the model crosses the IDL in 2D, it will be drawn in one viewport, but part of it
              // will be clipped by the viewport. We create a second command that translates the model
              // model matrix to the opposite side of the map so the part that was clipped in one viewport
              // is drawn in the other.
              command = primitiveCommand.command2D;
              if (defined(command) && model._mode === SceneMode$1.SCENE2D) {
                Matrix4.clone(nodeMatrix, command.modelMatrix);
                command.modelMatrix[13] -=
                  CesiumMath.sign(command.modelMatrix[13]) *
                  2.0 *
                  CesiumMath.PI *
                  projection.ellipsoid.maximumRadius;
                BoundingSphere.transform(
                  primitiveCommand.boundingSphere,
                  command.modelMatrix,
                  command.boundingVolume
                );
              }
            }
          }
        }

        var children = n.children;
        if (defined(children)) {
          var childrenLength = children.length;
          for (var k = 0; k < childrenLength; ++k) {
            var child = children[k];

            // A node's transform needs to be updated if
            // - It was targeted for animation this frame, or
            // - Any of its ancestors were targeted for animation this frame

            // PERFORMANCE_IDEA: if a child has multiple parents and only one of the parents
            // is dirty, all the subtrees for each child instance will be dirty; we probably
            // won't see this in the wild often.
            child.dirtyNumber = Math.max(child.dirtyNumber, n.dirtyNumber);

            if (child.dirtyNumber === maxDirtyNumber || justLoaded) {
              // Don't check for modelTransformChanged since if only the model's model matrix changed,
              // we do not need to rebuild the local transform-to-root, only the final
              // [model's-model-matrix][transform-to-root] above.
              getNodeMatrix(child, child.transformToRoot);
              Matrix4.multiplyTransformation(
                transformToRoot,
                child.transformToRoot,
                child.transformToRoot
              );
            }

            nodeStack.push(child);
          }
        }
      }
    }

    ++model._maxDirtyNumber;
  }

  var scratchObjectSpace = new Matrix4();

  function applySkins(model) {
    var skinnedNodes = model._runtime.skinnedNodes;
    var length = skinnedNodes.length;

    for (var i = 0; i < length; ++i) {
      var node = skinnedNodes[i];

      scratchObjectSpace = Matrix4.inverseTransformation(
        node.transformToRoot,
        scratchObjectSpace
      );

      var computedJointMatrices = node.computedJointMatrices;
      var joints = node.joints;
      var bindShapeMatrix = node.bindShapeMatrix;
      var inverseBindMatrices = node.inverseBindMatrices;
      var inverseBindMatricesLength = inverseBindMatrices.length;

      for (var m = 0; m < inverseBindMatricesLength; ++m) {
        // [joint-matrix] = [node-to-root^-1][joint-to-root][inverse-bind][bind-shape]
        if (!defined(computedJointMatrices[m])) {
          computedJointMatrices[m] = new Matrix4();
        }
        computedJointMatrices[m] = Matrix4.multiplyTransformation(
          scratchObjectSpace,
          joints[m].transformToRoot,
          computedJointMatrices[m]
        );
        computedJointMatrices[m] = Matrix4.multiplyTransformation(
          computedJointMatrices[m],
          inverseBindMatrices[m],
          computedJointMatrices[m]
        );
        if (defined(bindShapeMatrix)) {
          // NOTE: bindShapeMatrix is glTF 1.0 only, removed in glTF 2.0.
          computedJointMatrices[m] = Matrix4.multiplyTransformation(
            computedJointMatrices[m],
            bindShapeMatrix,
            computedJointMatrices[m]
          );
        }
      }
    }
  }

  function updatePerNodeShow(model) {
    // Totally not worth it, but we could optimize this:
    // http://help.agi.com/AGIComponents/html/BlogDeletionInBoundingVolumeHierarchies.htm

    var rootNodes = model._runtime.rootNodes;
    var length = rootNodes.length;

    var nodeStack = scratchNodeStack;

    for (var i = 0; i < length; ++i) {
      var n = rootNodes[i];
      n.computedShow = n.publicNode.show;
      nodeStack.push(n);

      while (nodeStack.length > 0) {
        n = nodeStack.pop();
        var show = n.computedShow;

        var nodeCommands = n.commands;
        var nodeCommandsLength = nodeCommands.length;
        for (var j = 0; j < nodeCommandsLength; ++j) {
          nodeCommands[j].show = show;
        }
        // if commandsLength is zero, the node has a light or camera

        var children = n.children;
        if (defined(children)) {
          var childrenLength = children.length;
          for (var k = 0; k < childrenLength; ++k) {
            var child = children[k];
            // Parent needs to be shown for child to be shown.
            child.computedShow = show && child.publicNode.show;
            nodeStack.push(child);
          }
        }
      }
    }
  }

  function updatePickIds(model, context) {
    var id = model.id;
    if (model._id !== id) {
      model._id = id;

      var pickIds = model._pickIds;
      var length = pickIds.length;
      for (var i = 0; i < length; ++i) {
        pickIds[i].object.id = id;
      }
    }
  }

  function updateWireframe$1(model) {
    if (model._debugWireframe !== model.debugWireframe) {
      model._debugWireframe = model.debugWireframe;

      // This assumes the original primitive was TRIANGLES and that the triangles
      // are connected for the wireframe to look perfect.
      var primitiveType = model.debugWireframe
        ? PrimitiveType$1.LINES
        : PrimitiveType$1.TRIANGLES;
      var nodeCommands = model._nodeCommands;
      var length = nodeCommands.length;

      for (var i = 0; i < length; ++i) {
        nodeCommands[i].command.primitiveType = primitiveType;
      }
    }
  }

  function updateShowBoundingVolume(model) {
    if (model.debugShowBoundingVolume !== model._debugShowBoundingVolume) {
      model._debugShowBoundingVolume = model.debugShowBoundingVolume;

      var debugShowBoundingVolume = model.debugShowBoundingVolume;
      var nodeCommands = model._nodeCommands;
      var length = nodeCommands.length;

      for (var i = 0; i < length; ++i) {
        nodeCommands[i].command.debugShowBoundingVolume = debugShowBoundingVolume;
      }
    }
  }

  function updateShadows(model) {
    if (model.shadows !== model._shadows) {
      model._shadows = model.shadows;

      var castShadows = ShadowMode$1.castShadows(model.shadows);
      var receiveShadows = ShadowMode$1.receiveShadows(model.shadows);
      var nodeCommands = model._nodeCommands;
      var length = nodeCommands.length;

      for (var i = 0; i < length; i++) {
        var nodeCommand = nodeCommands[i];
        nodeCommand.command.castShadows = castShadows;
        nodeCommand.command.receiveShadows = receiveShadows;
      }
    }
  }

  function getTranslucentRenderState$1(renderState) {
    var rs = clone(renderState, true);
    rs.cull.enabled = false;
    rs.depthTest.enabled = true;
    rs.depthMask = false;
    rs.blending = BlendingState$1.ALPHA_BLEND;

    return RenderState.fromCache(rs);
  }

  function deriveTranslucentCommand$1(command) {
    var translucentCommand = DrawCommand.shallowClone(command);
    translucentCommand.pass = Pass$1.TRANSLUCENT;
    translucentCommand.renderState = getTranslucentRenderState$1(
      command.renderState
    );
    return translucentCommand;
  }

  function updateColor(model, frameState, forceDerive) {
    // Generate translucent commands when the blend color has an alpha in the range (0.0, 1.0) exclusive
    var scene3DOnly = frameState.scene3DOnly;
    var alpha = model.color.alpha;
    if (alpha > 0.0 && alpha < 1.0) {
      var nodeCommands = model._nodeCommands;
      var length = nodeCommands.length;
      if (!defined(nodeCommands[0].translucentCommand) || forceDerive) {
        for (var i = 0; i < length; ++i) {
          var nodeCommand = nodeCommands[i];
          var command = nodeCommand.command;
          nodeCommand.translucentCommand = deriveTranslucentCommand$1(command);
          if (!scene3DOnly) {
            var command2D = nodeCommand.command2D;
            nodeCommand.translucentCommand2D = deriveTranslucentCommand$1(
              command2D
            );
          }
        }
      }
    }
  }

  function getDisableCullingRenderState(renderState) {
    var rs = clone(renderState, true);
    rs.cull.enabled = false;
    return RenderState.fromCache(rs);
  }

  function deriveDisableCullingCommand(command) {
    var disableCullingCommand = DrawCommand.shallowClone(command);
    disableCullingCommand.renderState = getDisableCullingRenderState(
      command.renderState
    );
    return disableCullingCommand;
  }

  function updateBackFaceCulling(model, frameState, forceDerive) {
    var scene3DOnly = frameState.scene3DOnly;
    var backFaceCulling = model.backFaceCulling;
    if (!backFaceCulling) {
      var nodeCommands = model._nodeCommands;
      var length = nodeCommands.length;
      if (!defined(nodeCommands[0].disableCullingCommand) || forceDerive) {
        for (var i = 0; i < length; ++i) {
          var nodeCommand = nodeCommands[i];
          var command = nodeCommand.command;
          nodeCommand.disableCullingCommand = deriveDisableCullingCommand(
            command
          );
          if (!scene3DOnly) {
            var command2D = nodeCommand.command2D;
            nodeCommand.disableCullingCommand2D = deriveDisableCullingCommand(
              command2D
            );
          }
        }
      }
    }
  }

  function getProgramId(model, program) {
    var programs = model._rendererResources.programs;
    for (var id in programs) {
      if (programs.hasOwnProperty(id)) {
        if (programs[id] === program) {
          return id;
        }
      }
    }
  }

  function createSilhouetteProgram(model, program, frameState) {
    var vs = program.vertexShaderSource.sources[0];
    var attributeLocations = program._attributeLocations;
    var normalAttributeName = model._normalAttributeName;

    // Modified from http://forum.unity3d.com/threads/toon-outline-but-with-diffuse-surface.24668/
    vs = ShaderSource.replaceMain(vs, "gltf_silhouette_main");
    vs +=
      "uniform float gltf_silhouetteSize; \n" +
      "void main() \n" +
      "{ \n" +
      "    gltf_silhouette_main(); \n" +
      "    vec3 n = normalize(czm_normal3D * " +
      normalAttributeName +
      "); \n" +
      "    n.x *= czm_projection[0][0]; \n" +
      "    n.y *= czm_projection[1][1]; \n" +
      "    vec4 clip = gl_Position; \n" +
      "    clip.xy += n.xy * clip.w * gltf_silhouetteSize * czm_pixelRatio / czm_viewport.z; \n" +
      "    gl_Position = clip; \n" +
      "}";

    var fs =
      "uniform vec4 gltf_silhouetteColor; \n" +
      "void main() \n" +
      "{ \n" +
      "    gl_FragColor = czm_gammaCorrect(gltf_silhouetteColor); \n" +
      "}";

    return ShaderProgram.fromCache({
      context: frameState.context,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations,
    });
  }

  function hasSilhouette(model, frameState) {
    return (
      silhouetteSupported(frameState.context) &&
      model.silhouetteSize > 0.0 &&
      model.silhouetteColor.alpha > 0.0 &&
      defined(model._normalAttributeName)
    );
  }

  function hasTranslucentCommands(model) {
    var nodeCommands = model._nodeCommands;
    var length = nodeCommands.length;
    for (var i = 0; i < length; ++i) {
      var nodeCommand = nodeCommands[i];
      var command = nodeCommand.command;
      if (command.pass === Pass$1.TRANSLUCENT) {
        return true;
      }
    }
    return false;
  }

  function isTranslucent(model) {
    return model.color.alpha > 0.0 && model.color.alpha < 1.0;
  }

  function isInvisible(model) {
    return model.color.alpha === 0.0;
  }

  function alphaDirty(currAlpha, prevAlpha) {
    // Returns whether the alpha state has changed between invisible, translucent, or opaque
    return (
      Math.floor(currAlpha) !== Math.floor(prevAlpha) ||
      Math.ceil(currAlpha) !== Math.ceil(prevAlpha)
    );
  }

  var silhouettesLength = 0;

  function createSilhouetteCommands(model, frameState) {
    // Wrap around after exceeding the 8-bit stencil limit.
    // The reference is unique to each model until this point.
    var stencilReference = ++silhouettesLength % 255;

    // If the model is translucent the silhouette needs to be in the translucent pass.
    // Otherwise the silhouette would be rendered before the model.
    var silhouetteTranslucent =
      hasTranslucentCommands(model) ||
      isTranslucent(model) ||
      model.silhouetteColor.alpha < 1.0;
    var silhouettePrograms = model._rendererResources.silhouettePrograms;
    var scene3DOnly = frameState.scene3DOnly;
    var nodeCommands = model._nodeCommands;
    var length = nodeCommands.length;
    for (var i = 0; i < length; ++i) {
      var nodeCommand = nodeCommands[i];
      var command = nodeCommand.command;

      // Create model command
      var modelCommand = isTranslucent(model)
        ? nodeCommand.translucentCommand
        : command;
      var silhouetteModelCommand = DrawCommand.shallowClone(modelCommand);
      var renderState = clone(modelCommand.renderState);

      // Write the reference value into the stencil buffer.
      renderState.stencilTest = {
        enabled: true,
        frontFunction: WebGLConstants$1.ALWAYS,
        backFunction: WebGLConstants$1.ALWAYS,
        reference: stencilReference,
        mask: ~0,
        frontOperation: {
          fail: WebGLConstants$1.KEEP,
          zFail: WebGLConstants$1.KEEP,
          zPass: WebGLConstants$1.REPLACE,
        },
        backOperation: {
          fail: WebGLConstants$1.KEEP,
          zFail: WebGLConstants$1.KEEP,
          zPass: WebGLConstants$1.REPLACE,
        },
      };

      if (isInvisible(model)) {
        // When the model is invisible disable color and depth writes but still write into the stencil buffer
        renderState.colorMask = {
          red: false,
          green: false,
          blue: false,
          alpha: false,
        };
        renderState.depthMask = false;
      }
      renderState = RenderState.fromCache(renderState);
      silhouetteModelCommand.renderState = renderState;
      nodeCommand.silhouetteModelCommand = silhouetteModelCommand;

      // Create color command
      var silhouetteColorCommand = DrawCommand.shallowClone(command);
      renderState = clone(command.renderState, true);
      renderState.depthTest.enabled = true;
      renderState.cull.enabled = false;
      if (silhouetteTranslucent) {
        silhouetteColorCommand.pass = Pass$1.TRANSLUCENT;
        renderState.depthMask = false;
        renderState.blending = BlendingState$1.ALPHA_BLEND;
      }

      // Only render silhouette if the value in the stencil buffer equals the reference
      renderState.stencilTest = {
        enabled: true,
        frontFunction: WebGLConstants$1.NOTEQUAL,
        backFunction: WebGLConstants$1.NOTEQUAL,
        reference: stencilReference,
        mask: ~0,
        frontOperation: {
          fail: WebGLConstants$1.KEEP,
          zFail: WebGLConstants$1.KEEP,
          zPass: WebGLConstants$1.KEEP,
        },
        backOperation: {
          fail: WebGLConstants$1.KEEP,
          zFail: WebGLConstants$1.KEEP,
          zPass: WebGLConstants$1.KEEP,
        },
      };
      renderState = RenderState.fromCache(renderState);

      // If the silhouette program has already been cached use it
      var program = command.shaderProgram;
      var id = getProgramId(model, program);
      var silhouetteProgram = silhouettePrograms[id];
      if (!defined(silhouetteProgram)) {
        silhouetteProgram = createSilhouetteProgram(model, program, frameState);
        silhouettePrograms[id] = silhouetteProgram;
      }

      var silhouetteUniformMap = combine(command.uniformMap, {
        gltf_silhouetteColor: createSilhouetteColorFunction(model),
        gltf_silhouetteSize: createSilhouetteSizeFunction(model),
      });

      silhouetteColorCommand.renderState = renderState;
      silhouetteColorCommand.shaderProgram = silhouetteProgram;
      silhouetteColorCommand.uniformMap = silhouetteUniformMap;
      silhouetteColorCommand.castShadows = false;
      silhouetteColorCommand.receiveShadows = false;
      nodeCommand.silhouetteColorCommand = silhouetteColorCommand;

      if (!scene3DOnly) {
        var command2D = nodeCommand.command2D;
        var silhouetteModelCommand2D = DrawCommand.shallowClone(
          silhouetteModelCommand
        );
        silhouetteModelCommand2D.boundingVolume = command2D.boundingVolume;
        silhouetteModelCommand2D.modelMatrix = command2D.modelMatrix;
        nodeCommand.silhouetteModelCommand2D = silhouetteModelCommand2D;

        var silhouetteColorCommand2D = DrawCommand.shallowClone(
          silhouetteColorCommand
        );
        silhouetteModelCommand2D.boundingVolume = command2D.boundingVolume;
        silhouetteModelCommand2D.modelMatrix = command2D.modelMatrix;
        nodeCommand.silhouetteColorCommand2D = silhouetteColorCommand2D;
      }
    }
  }

  function modifyShaderForClippingPlanes(
    shader,
    clippingPlaneCollection,
    context
  ) {
    shader = ShaderSource.replaceMain(shader, "gltf_clip_main");
    shader += Model._getClippingFunction(clippingPlaneCollection, context) + "\n";
    shader +=
      "uniform highp sampler2D gltf_clippingPlanes; \n" +
      "uniform mat4 gltf_clippingPlanesMatrix; \n" +
      "uniform vec4 gltf_clippingPlanesEdgeStyle; \n" +
      "void main() \n" +
      "{ \n" +
      "    gltf_clip_main(); \n" +
      getClipAndStyleCode(
        "gltf_clippingPlanes",
        "gltf_clippingPlanesMatrix",
        "gltf_clippingPlanesEdgeStyle"
      ) +
      "} \n";
    return shader;
  }

  function updateSilhouette(model, frameState, force) {
    // Generate silhouette commands when the silhouette size is greater than 0.0 and the alpha is greater than 0.0
    // There are two silhouette commands:
    //     1. silhouetteModelCommand : render model normally while enabling stencil mask
    //     2. silhouetteColorCommand : render enlarged model with a solid color while enabling stencil tests
    if (!hasSilhouette(model, frameState)) {
      return;
    }

    var nodeCommands = model._nodeCommands;
    var dirty =
      alphaDirty(model.color.alpha, model._colorPreviousAlpha) ||
      alphaDirty(
        model.silhouetteColor.alpha,
        model._silhouetteColorPreviousAlpha
      ) ||
      !defined(nodeCommands[0].silhouetteModelCommand);

    model._colorPreviousAlpha = model.color.alpha;
    model._silhouetteColorPreviousAlpha = model.silhouetteColor.alpha;

    if (dirty || force) {
      createSilhouetteCommands(model, frameState);
    }
  }

  function updateClippingPlanes(model, frameState) {
    var clippingPlanes = model._clippingPlanes;
    if (defined(clippingPlanes) && clippingPlanes.owner === model) {
      if (clippingPlanes.enabled) {
        clippingPlanes.update(frameState);
      }
    }
  }

  var scratchBoundingSphere$3 = new BoundingSphere();

  function scaleInPixels(positionWC, radius, frameState) {
    scratchBoundingSphere$3.center = positionWC;
    scratchBoundingSphere$3.radius = radius;
    return frameState.camera.getPixelSize(
      scratchBoundingSphere$3,
      frameState.context.drawingBufferWidth,
      frameState.context.drawingBufferHeight
    );
  }

  var scratchPosition$6 = new Cartesian3();
  var scratchCartographic$3 = new Cartographic();

  function getScale(model, frameState) {
    var scale = model.scale;

    if (model.minimumPixelSize !== 0.0) {
      // Compute size of bounding sphere in pixels
      var context = frameState.context;
      var maxPixelSize = Math.max(
        context.drawingBufferWidth,
        context.drawingBufferHeight
      );
      var m = defined(model._clampedModelMatrix)
        ? model._clampedModelMatrix
        : model.modelMatrix;
      scratchPosition$6.x = m[12];
      scratchPosition$6.y = m[13];
      scratchPosition$6.z = m[14];

      if (defined(model._rtcCenter)) {
        Cartesian3.add(model._rtcCenter, scratchPosition$6, scratchPosition$6);
      }

      if (model._mode !== SceneMode$1.SCENE3D) {
        var projection = frameState.mapProjection;
        var cartographic = projection.ellipsoid.cartesianToCartographic(
          scratchPosition$6,
          scratchCartographic$3
        );
        projection.project(cartographic, scratchPosition$6);
        Cartesian3.fromElements(
          scratchPosition$6.z,
          scratchPosition$6.x,
          scratchPosition$6.y,
          scratchPosition$6
        );
      }

      var radius = model.boundingSphere.radius;
      var metersPerPixel = scaleInPixels(scratchPosition$6, radius, frameState);

      // metersPerPixel is always > 0.0
      var pixelsPerMeter = 1.0 / metersPerPixel;
      var diameterInPixels = Math.min(
        pixelsPerMeter * (2.0 * radius),
        maxPixelSize
      );

      // Maintain model's minimum pixel size
      if (diameterInPixels < model.minimumPixelSize) {
        scale =
          (model.minimumPixelSize * metersPerPixel) /
          (2.0 * model._initialRadius);
      }
    }

    return defined(model.maximumScale)
      ? Math.min(model.maximumScale, scale)
      : scale;
  }

  function releaseCachedGltf(model) {
    if (
      defined(model._cacheKey) &&
      defined(model._cachedGltf) &&
      --model._cachedGltf.count === 0
    ) {
      delete gltfCache[model._cacheKey];
    }
    model._cachedGltf = undefined;
  }

  ///////////////////////////////////////////////////////////////////////////

  function CachedRendererResources(context, cacheKey) {
    this.buffers = undefined;
    this.vertexArrays = undefined;
    this.programs = undefined;
    this.sourceShaders = undefined;
    this.silhouettePrograms = undefined;
    this.textures = undefined;
    this.samplers = undefined;
    this.renderStates = undefined;
    this.ready = false;

    this.context = context;
    this.cacheKey = cacheKey;
    this.count = 0;
  }

  function destroy(property) {
    for (var name in property) {
      if (property.hasOwnProperty(name)) {
        property[name].destroy();
      }
    }
  }

  function destroyCachedRendererResources(resources) {
    destroy(resources.buffers);
    destroy(resources.vertexArrays);
    destroy(resources.programs);
    destroy(resources.silhouettePrograms);
    destroy(resources.textures);
  }

  CachedRendererResources.prototype.release = function () {
    if (--this.count === 0) {
      if (defined(this.cacheKey)) {
        // Remove if this was cached
        delete this.context.cache.modelRendererResourceCache[this.cacheKey];
      }
      destroyCachedRendererResources(this);
      return destroyObject(this);
    }

    return undefined;
  };

  ///////////////////////////////////////////////////////////////////////////

  function getUpdateHeightCallback(model, ellipsoid, cartoPosition) {
    return function (clampedPosition) {
      if (model.heightReference === HeightReference$1.RELATIVE_TO_GROUND) {
        var clampedCart = ellipsoid.cartesianToCartographic(
          clampedPosition,
          scratchCartographic$3
        );
        clampedCart.height += cartoPosition.height;
        ellipsoid.cartographicToCartesian(clampedCart, clampedPosition);
      }

      var clampedModelMatrix = model._clampedModelMatrix;

      // Modify clamped model matrix to use new height
      Matrix4.clone(model.modelMatrix, clampedModelMatrix);
      clampedModelMatrix[12] = clampedPosition.x;
      clampedModelMatrix[13] = clampedPosition.y;
      clampedModelMatrix[14] = clampedPosition.z;

      model._heightChanged = true;
    };
  }

  function updateClamping(model) {
    if (defined(model._removeUpdateHeightCallback)) {
      model._removeUpdateHeightCallback();
      model._removeUpdateHeightCallback = undefined;
    }

    var scene = model._scene;
    if (
      !defined(scene) ||
      !defined(scene.globe) ||
      model.heightReference === HeightReference$1.NONE
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (model.heightReference !== HeightReference$1.NONE) {
        throw new DeveloperError(
          "Height reference is not supported without a scene and globe."
        );
      }
      //>>includeEnd('debug');
      model._clampedModelMatrix = undefined;
      return;
    }

    var globe = scene.globe;
    var ellipsoid = globe.ellipsoid;

    // Compute cartographic position so we don't recompute every update
    var modelMatrix = model.modelMatrix;
    scratchPosition$6.x = modelMatrix[12];
    scratchPosition$6.y = modelMatrix[13];
    scratchPosition$6.z = modelMatrix[14];
    var cartoPosition = ellipsoid.cartesianToCartographic(scratchPosition$6);

    if (!defined(model._clampedModelMatrix)) {
      model._clampedModelMatrix = Matrix4.clone(modelMatrix, new Matrix4());
    }

    // Install callback to handle updating of terrain tiles
    var surface = globe._surface;
    model._removeUpdateHeightCallback = surface.updateHeight(
      cartoPosition,
      getUpdateHeightCallback(model, ellipsoid, cartoPosition)
    );

    // Set the correct height now
    var height = globe.getHeight(cartoPosition);
    if (defined(height)) {
      // Get callback with cartoPosition being the non-clamped position
      var cb = getUpdateHeightCallback(model, ellipsoid, cartoPosition);

      // Compute the clamped cartesian and call updateHeight callback
      Cartographic.clone(cartoPosition, scratchCartographic$3);
      scratchCartographic$3.height = height;
      ellipsoid.cartographicToCartesian(scratchCartographic$3, scratchPosition$6);
      cb(scratchPosition$6);
    }
  }

  var scratchDisplayConditionCartesian = new Cartesian3();
  var scratchDistanceDisplayConditionCartographic = new Cartographic();

  function distanceDisplayConditionVisible(model, frameState) {
    var distance2;
    var ddc = model.distanceDisplayCondition;
    var nearSquared = ddc.near * ddc.near;
    var farSquared = ddc.far * ddc.far;

    if (frameState.mode === SceneMode$1.SCENE2D) {
      var frustum2DWidth =
        frameState.camera.frustum.right - frameState.camera.frustum.left;
      distance2 = frustum2DWidth * 0.5;
      distance2 = distance2 * distance2;
    } else {
      // Distance to center of primitive's reference frame
      var position = Matrix4.getTranslation(
        model.modelMatrix,
        scratchDisplayConditionCartesian
      );
      if (frameState.mode === SceneMode$1.COLUMBUS_VIEW) {
        var projection = frameState.mapProjection;
        var ellipsoid = projection.ellipsoid;
        var cartographic = ellipsoid.cartesianToCartographic(
          position,
          scratchDistanceDisplayConditionCartographic
        );
        position = projection.project(cartographic, position);
        Cartesian3.fromElements(position.z, position.x, position.y, position);
      }
      distance2 = Cartesian3.distanceSquared(
        position,
        frameState.camera.positionWC
      );
    }

    return distance2 >= nearSquared && distance2 <= farSquared;
  }

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {RuntimeError} Failed to load external reference.
   */
  Model.prototype.update = function (frameState) {
    if (frameState.mode === SceneMode$1.MORPHING) {
      return;
    }

    if (!FeatureDetection.supportsWebP.initialized) {
      FeatureDetection.supportsWebP.initialize();
      return;
    }
    var supportsWebP = FeatureDetection.supportsWebP();

    var context = frameState.context;
    this._defaultTexture = context.defaultTexture;

    if (this._state === ModelState$1.NEEDS_LOAD && defined(this.gltf)) {
      // Use renderer resources from cache instead of loading/creating them?
      var cachedRendererResources;
      var cacheKey = this.cacheKey;
      if (defined(cacheKey)) {
        // cache key given? this model will pull from or contribute to context level cache
        context.cache.modelRendererResourceCache = defaultValue(
          context.cache.modelRendererResourceCache,
          {}
        );
        var modelCaches = context.cache.modelRendererResourceCache;

        cachedRendererResources = modelCaches[this.cacheKey];
        if (defined(cachedRendererResources)) {
          if (!cachedRendererResources.ready) {
            // Cached resources for the model are not loaded yet.  We'll
            // try again every frame until they are.
            return;
          }

          ++cachedRendererResources.count;
          this._loadRendererResourcesFromCache = true;
        } else {
          cachedRendererResources = new CachedRendererResources(
            context,
            cacheKey
          );
          cachedRendererResources.count = 1;
          modelCaches[this.cacheKey] = cachedRendererResources;
        }
        this._cachedRendererResources = cachedRendererResources;
      } else {
        // cache key not given? this model doesn't care about context level cache at all. Cache is here to simplify freeing on destroy.
        cachedRendererResources = new CachedRendererResources(context);
        cachedRendererResources.count = 1;
        this._cachedRendererResources = cachedRendererResources;
      }

      this._state = ModelState$1.LOADING;
      if (this._state !== ModelState$1.FAILED) {
        var extensions = this.gltf.extensions;
        if (defined(extensions) && defined(extensions.CESIUM_RTC)) {
          var center = Cartesian3.fromArray(extensions.CESIUM_RTC.center);
          if (!Cartesian3.equals(center, Cartesian3.ZERO)) {
            this._rtcCenter3D = center;

            var projection = frameState.mapProjection;
            var ellipsoid = projection.ellipsoid;
            var cartographic = ellipsoid.cartesianToCartographic(
              this._rtcCenter3D
            );
            var projectedCart = projection.project(cartographic);
            Cartesian3.fromElements(
              projectedCart.z,
              projectedCart.x,
              projectedCart.y,
              projectedCart
            );
            this._rtcCenter2D = projectedCart;

            this._rtcCenterEye = new Cartesian3();
            this._rtcCenter = this._rtcCenter3D;
          }
        }

        addPipelineExtras(this.gltf);

        this._loadResources = new ModelLoadResources();
        if (!this._loadRendererResourcesFromCache) {
          // Buffers are required to updateVersion
          ModelUtility.parseBuffers(this, bufferLoad);
        }
      }
    }

    var loadResources = this._loadResources;
    var incrementallyLoadTextures = this._incrementallyLoadTextures;
    var justLoaded = false;

    if (this._state === ModelState$1.LOADING) {
      // Transition from LOADING -> LOADED once resources are downloaded and created.
      // Textures may continue to stream in while in the LOADED state.
      if (loadResources.pendingBufferLoads === 0) {
        if (!loadResources.initialized) {
          frameState.brdfLutGenerator.update(frameState);

          ModelUtility.checkSupportedExtensions(
            this.extensionsRequired,
            supportsWebP
          );
          ModelUtility.updateForwardAxis(this);

          // glTF pipeline updates, not needed if loading from cache
          if (!defined(this.gltf.extras.sourceVersion)) {
            var gltf = this.gltf;
            // Add the original version so it remains cached
            gltf.extras.sourceVersion = ModelUtility.getAssetVersion(gltf);
            gltf.extras.sourceKHRTechniquesWebGL = defined(
              ModelUtility.getUsedExtensions(gltf).KHR_techniques_webgl
            );

            this._sourceVersion = gltf.extras.sourceVersion;
            this._sourceKHRTechniquesWebGL = gltf.extras.sourceKHRTechniquesWebGL;

            updateVersion(gltf);
            addDefaults(gltf);

            var options = {
              addBatchIdToGeneratedShaders: this._addBatchIdToGeneratedShaders,
            };

            processModelMaterialsCommon(gltf, options);
            processPbrMaterials(gltf, options);
          }

          this._sourceVersion = this.gltf.extras.sourceVersion;
          this._sourceKHRTechniquesWebGL = this.gltf.extras.sourceKHRTechniquesWebGL;

          // Skip dequantizing in the shader if not encoded
          this._dequantizeInShader =
            this._dequantizeInShader && DracoLoader.hasExtension(this);

          // We do this after to make sure that the ids don't change
          addBuffersToLoadResources$1(this);
          parseArticulations(this);
          parseTechniques(this);
          if (!this._loadRendererResourcesFromCache) {
            parseBufferViews$1(this);
            parseShaders(this);
            parsePrograms(this);
            parseTextures(this, context, supportsWebP);
          }
          parseMaterials(this);
          parseMeshes(this);
          parseNodes(this);

          // Start draco decoding
          DracoLoader.parse(this, context);

          loadResources.initialized = true;
        }

        if (!loadResources.finishedDecoding()) {
          DracoLoader.decodeModel(this, context).otherwise(
            ModelUtility.getFailedLoadFunction(this, "model", this.basePath)
          );
        }

        if (loadResources.finishedDecoding() && !loadResources.resourcesParsed) {
          this._boundingSphere = ModelUtility.computeBoundingSphere(this);
          this._initialRadius = this._boundingSphere.radius;

          DracoLoader.cacheDataForModel(this);

          loadResources.resourcesParsed = true;
        }

        if (
          loadResources.resourcesParsed &&
          loadResources.pendingShaderLoads === 0
        ) {
          ModelOutlineLoader.outlinePrimitives(this);
          createResources$1(this, frameState);
        }
      }

      if (
        loadResources.finished() ||
        (incrementallyLoadTextures &&
          loadResources.finishedEverythingButTextureCreation())
      ) {
        this._state = ModelState$1.LOADED;
        justLoaded = true;
      }
    }

    // Incrementally stream textures.
    if (defined(loadResources) && this._state === ModelState$1.LOADED) {
      if (incrementallyLoadTextures && !justLoaded) {
        createResources$1(this, frameState);
      }

      if (loadResources.finished()) {
        this._loadResources = undefined; // Clear CPU memory since WebGL resources were created.

        var resources = this._rendererResources;
        var cachedResources = this._cachedRendererResources;

        cachedResources.buffers = resources.buffers;
        cachedResources.vertexArrays = resources.vertexArrays;
        cachedResources.programs = resources.programs;
        cachedResources.sourceShaders = resources.sourceShaders;
        cachedResources.silhouettePrograms = resources.silhouettePrograms;
        cachedResources.textures = resources.textures;
        cachedResources.samplers = resources.samplers;
        cachedResources.renderStates = resources.renderStates;
        cachedResources.ready = true;

        // The normal attribute name is required for silhouettes, so get it before the gltf JSON is released
        this._normalAttributeName = ModelUtility.getAttributeOrUniformBySemantic(
          this.gltf,
          "NORMAL"
        );

        // Vertex arrays are unique to this model, do not store in cache.
        if (defined(this._precreatedAttributes)) {
          cachedResources.vertexArrays = {};
        }

        if (this.releaseGltfJson) {
          releaseCachedGltf(this);
        }
      }
    }

    var iblSupported = OctahedralProjectedCubeMap.isSupported(context);
    if (this._shouldUpdateSpecularMapAtlas && iblSupported) {
      this._shouldUpdateSpecularMapAtlas = false;
      this._specularEnvironmentMapAtlas =
        this._specularEnvironmentMapAtlas &&
        this._specularEnvironmentMapAtlas.destroy();
      this._specularEnvironmentMapAtlas = undefined;
      if (defined(this._specularEnvironmentMaps)) {
        this._specularEnvironmentMapAtlas = new OctahedralProjectedCubeMap(
          this._specularEnvironmentMaps
        );
        var that = this;
        this._specularEnvironmentMapAtlas.readyPromise
          .then(function () {
            that._shouldRegenerateShaders = true;
          })
          .otherwise(function (error) {
            console.error("Error loading specularEnvironmentMaps: " + error);
          });
      }

      // Regenerate shaders to not use an environment map. Will be set to true again if there was a new environment map and it is ready.
      this._shouldRegenerateShaders = true;
    }

    if (defined(this._specularEnvironmentMapAtlas)) {
      this._specularEnvironmentMapAtlas.update(frameState);
    }

    var recompileWithDefaultAtlas =
      !defined(this._specularEnvironmentMapAtlas) &&
      defined(frameState.specularEnvironmentMaps) &&
      !this._useDefaultSpecularMaps;
    var recompileWithoutDefaultAtlas =
      !defined(frameState.specularEnvironmentMaps) &&
      this._useDefaultSpecularMaps;

    var recompileWithDefaultSHCoeffs =
      !defined(this._sphericalHarmonicCoefficients) &&
      defined(frameState.sphericalHarmonicCoefficients) &&
      !this._useDefaultSphericalHarmonics;
    var recompileWithoutDefaultSHCoeffs =
      !defined(frameState.sphericalHarmonicCoefficients) &&
      this._useDefaultSphericalHarmonics;

    this._shouldRegenerateShaders =
      this._shouldRegenerateShaders ||
      recompileWithDefaultAtlas ||
      recompileWithoutDefaultAtlas ||
      recompileWithDefaultSHCoeffs ||
      recompileWithoutDefaultSHCoeffs;

    this._useDefaultSpecularMaps =
      !defined(this._specularEnvironmentMapAtlas) &&
      defined(frameState.specularEnvironmentMaps);
    this._useDefaultSphericalHarmonics =
      !defined(this._sphericalHarmonicCoefficients) &&
      defined(frameState.sphericalHarmonicCoefficients);

    var silhouette = hasSilhouette(this, frameState);
    var translucent = isTranslucent(this);
    var invisible = isInvisible(this);
    var backFaceCulling = this.backFaceCulling;
    var displayConditionPassed = defined(this.distanceDisplayCondition)
      ? distanceDisplayConditionVisible(this, frameState)
      : true;
    var show =
      this.show &&
      displayConditionPassed &&
      this.scale !== 0.0 &&
      (!invisible || silhouette);

    if ((show && this._state === ModelState$1.LOADED) || justLoaded) {
      var animated =
        this.activeAnimations.update(frameState) || this._cesiumAnimationsDirty;
      this._cesiumAnimationsDirty = false;
      this._dirty = false;
      var modelMatrix = this.modelMatrix;

      var modeChanged = frameState.mode !== this._mode;
      this._mode = frameState.mode;

      // Model's model matrix needs to be updated
      var modelTransformChanged =
        !Matrix4.equals(this._modelMatrix, modelMatrix) ||
        this._scale !== this.scale ||
        this._minimumPixelSize !== this.minimumPixelSize ||
        this.minimumPixelSize !== 0.0 || // Minimum pixel size changed or is enabled
        this._maximumScale !== this.maximumScale ||
        this._heightReference !== this.heightReference ||
        this._heightChanged ||
        modeChanged;

      if (modelTransformChanged || justLoaded) {
        Matrix4.clone(modelMatrix, this._modelMatrix);

        updateClamping(this);

        if (defined(this._clampedModelMatrix)) {
          modelMatrix = this._clampedModelMatrix;
        }

        this._scale = this.scale;
        this._minimumPixelSize = this.minimumPixelSize;
        this._maximumScale = this.maximumScale;
        this._heightReference = this.heightReference;
        this._heightChanged = false;

        var scale = getScale(this, frameState);
        var computedModelMatrix = this._computedModelMatrix;
        Matrix4.multiplyByUniformScale(modelMatrix, scale, computedModelMatrix);
        if (this._upAxis === Axis$1.Y) {
          Matrix4.multiplyTransformation(
            computedModelMatrix,
            Axis$1.Y_UP_TO_Z_UP,
            computedModelMatrix
          );
        } else if (this._upAxis === Axis$1.X) {
          Matrix4.multiplyTransformation(
            computedModelMatrix,
            Axis$1.X_UP_TO_Z_UP,
            computedModelMatrix
          );
        }
        if (this.forwardAxis === Axis$1.Z) {
          // glTF 2.0 has a Z-forward convention that must be adapted here to X-forward.
          Matrix4.multiplyTransformation(
            computedModelMatrix,
            Axis$1.Z_UP_TO_X_UP,
            computedModelMatrix
          );
        }
      }

      // Update modelMatrix throughout the graph as needed
      if (animated || modelTransformChanged || justLoaded) {
        updateNodeHierarchyModelMatrix(
          this,
          modelTransformChanged,
          justLoaded,
          frameState.mapProjection
        );
        this._dirty = true;

        if (animated || justLoaded) {
          // Apply skins if animation changed any node transforms
          applySkins(this);
        }
      }

      if (this._perNodeShowDirty) {
        this._perNodeShowDirty = false;
        updatePerNodeShow(this);
      }
      updatePickIds(this);
      updateWireframe$1(this);
      updateShowBoundingVolume(this);
      updateShadows(this);
      updateClippingPlanes(this, frameState);

      // Regenerate shaders if ClippingPlaneCollection state changed or it was removed
      var clippingPlanes = this._clippingPlanes;
      var currentClippingPlanesState = 0;
      var useClippingPlanes =
        defined(clippingPlanes) &&
        clippingPlanes.enabled &&
        clippingPlanes.length > 0;
      var usesSH =
        defined(this._sphericalHarmonicCoefficients) ||
        this._useDefaultSphericalHarmonics;
      var usesSM =
        (defined(this._specularEnvironmentMapAtlas) &&
          this._specularEnvironmentMapAtlas.ready) ||
        this._useDefaultSpecularMaps;
      if (useClippingPlanes || usesSH || usesSM) {
        var clippingPlanesOriginMatrix = defaultValue(
          this.clippingPlanesOriginMatrix,
          modelMatrix
        );
        Matrix4.multiply(
          context.uniformState.view3D,
          clippingPlanesOriginMatrix,
          this._clippingPlaneModelViewMatrix
        );
      }

      if (useClippingPlanes) {
        currentClippingPlanesState = clippingPlanes.clippingPlanesState;
      }

      var shouldRegenerateShaders = this._shouldRegenerateShaders;
      shouldRegenerateShaders =
        shouldRegenerateShaders ||
        this._clippingPlanesState !== currentClippingPlanesState;
      this._clippingPlanesState = currentClippingPlanesState;

      // Regenerate shaders if color shading changed from last update
      var currentlyColorShadingEnabled = isColorShadingEnabled(this);
      if (currentlyColorShadingEnabled !== this._colorShadingEnabled) {
        this._colorShadingEnabled = currentlyColorShadingEnabled;
        shouldRegenerateShaders = true;
      }

      if (shouldRegenerateShaders) {
        regenerateShaders(this, frameState);
      } else {
        updateColor(this, frameState, false);
        updateBackFaceCulling(this, frameState, false);
        updateSilhouette(this, frameState, false);
      }
    }

    if (justLoaded) {
      // Called after modelMatrix update.
      var model = this;
      frameState.afterRender.push(function () {
        model._ready = true;
        model._readyPromise.resolve(model);
      });
      return;
    }

    // We don't check show at the top of the function since we
    // want to be able to progressively load models when they are not shown,
    // and then have them visible immediately when show is set to true.
    if (show && !this._ignoreCommands) {
      // PERFORMANCE_IDEA: This is terrible
      var commandList = frameState.commandList;
      var passes = frameState.passes;
      var nodeCommands = this._nodeCommands;
      var length = nodeCommands.length;
      var i;
      var nc;

      var idl2D =
        frameState.mapProjection.ellipsoid.maximumRadius * CesiumMath.PI;
      var boundingVolume;

      if (passes.render || (passes.pick && this.allowPicking)) {
        for (i = 0; i < length; ++i) {
          nc = nodeCommands[i];
          if (nc.show) {
            var command = nc.command;
            if (silhouette) {
              command = nc.silhouetteModelCommand;
            } else if (translucent) {
              command = nc.translucentCommand;
            } else if (!backFaceCulling) {
              command = nc.disableCullingCommand;
            }
            commandList.push(command);
            boundingVolume = nc.command.boundingVolume;
            if (
              frameState.mode === SceneMode$1.SCENE2D &&
              (boundingVolume.center.y + boundingVolume.radius > idl2D ||
                boundingVolume.center.y - boundingVolume.radius < idl2D)
            ) {
              var command2D = nc.command2D;
              if (silhouette) {
                command2D = nc.silhouetteModelCommand2D;
              } else if (translucent) {
                command2D = nc.translucentCommand2D;
              } else if (!backFaceCulling) {
                command2D = nc.disableCullingCommand2D;
              }
              commandList.push(command2D);
            }
          }
        }

        if (silhouette && !passes.pick) {
          // Render second silhouette pass
          for (i = 0; i < length; ++i) {
            nc = nodeCommands[i];
            if (nc.show) {
              commandList.push(nc.silhouetteColorCommand);
              boundingVolume = nc.command.boundingVolume;
              if (
                frameState.mode === SceneMode$1.SCENE2D &&
                (boundingVolume.center.y + boundingVolume.radius > idl2D ||
                  boundingVolume.center.y - boundingVolume.radius < idl2D)
              ) {
                commandList.push(nc.silhouetteColorCommand2D);
              }
            }
          }
        }
      }
    }

    var credit = this._credit;
    if (defined(credit)) {
      frameState.creditDisplay.addCredit(credit);
    }

    var resourceCredits = this._resourceCredits;
    var creditCount = resourceCredits.length;
    for (var c = 0; c < creditCount; c++) {
      frameState.creditDisplay.addCredit(resourceCredits[c]);
    }
  };

  function destroyIfNotCached(rendererResources, cachedRendererResources) {
    if (rendererResources.programs !== cachedRendererResources.programs) {
      destroy(rendererResources.programs);
    }
    if (
      rendererResources.silhouettePrograms !==
      cachedRendererResources.silhouettePrograms
    ) {
      destroy(rendererResources.silhouettePrograms);
    }
  }

  // Run from update iff:
  // - everything is loaded
  // - clipping planes state change OR color state set
  // Run this from destructor after removing color state and clipping plane state
  function regenerateShaders(model, frameState) {
    // In regards to _cachedRendererResources:
    // Fair to assume that this is data that should just never get modified due to clipping planes or model color.
    // So if clipping planes or model color active:
    // - delink _rendererResources.*programs and create new dictionaries.
    // - do NOT destroy any programs - might be used by copies of the model or by might be needed in the future if clipping planes/model color is deactivated

    // If clipping planes and model color inactive:
    // - destroy _rendererResources.*programs
    // - relink _rendererResources.*programs to _cachedRendererResources

    // In both cases, need to mark commands as dirty, re-run derived commands (elsewhere)

    var rendererResources = model._rendererResources;
    var cachedRendererResources = model._cachedRendererResources;
    destroyIfNotCached(rendererResources, cachedRendererResources);

    var programId;
    if (
      isClippingEnabled(model) ||
      isColorShadingEnabled(model) ||
      model._shouldRegenerateShaders
    ) {
      model._shouldRegenerateShaders = false;

      rendererResources.programs = {};
      rendererResources.silhouettePrograms = {};

      var visitedPrograms = {};
      var techniques = model._sourceTechniques;
      var technique;

      for (var techniqueId in techniques) {
        if (techniques.hasOwnProperty(techniqueId)) {
          technique = techniques[techniqueId];
          programId = technique.program;
          if (!visitedPrograms[programId]) {
            visitedPrograms[programId] = true;
            recreateProgram(
              {
                programId: programId,
                techniqueId: techniqueId,
              },
              model,
              frameState.context
            );
          }
        }
      }
    } else {
      rendererResources.programs = cachedRendererResources.programs;
      rendererResources.silhouettePrograms =
        cachedRendererResources.silhouettePrograms;
    }

    // Fix all the commands, marking them as dirty so everything that derives will re-derive
    var rendererPrograms = rendererResources.programs;

    var nodeCommands = model._nodeCommands;
    var commandCount = nodeCommands.length;
    for (var i = 0; i < commandCount; ++i) {
      var nodeCommand = nodeCommands[i];
      programId = nodeCommand.programId;

      var renderProgram = rendererPrograms[programId];
      nodeCommand.command.shaderProgram = renderProgram;
      if (defined(nodeCommand.command2D)) {
        nodeCommand.command2D.shaderProgram = renderProgram;
      }
    }

    // Force update silhouette commands/shaders
    updateColor(model, frameState, true);
    updateBackFaceCulling(model, frameState, true);
    updateSilhouette(model, frameState, true);
  }

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Model#destroy
   */
  Model.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * model = model && model.destroy();
   *
   * @see Model#isDestroyed
   */
  Model.prototype.destroy = function () {
    // Vertex arrays are unique to this model, destroy here.
    if (defined(this._precreatedAttributes)) {
      destroy(this._rendererResources.vertexArrays);
    }

    if (defined(this._removeUpdateHeightCallback)) {
      this._removeUpdateHeightCallback();
      this._removeUpdateHeightCallback = undefined;
    }

    if (defined(this._terrainProviderChangedCallback)) {
      this._terrainProviderChangedCallback();
      this._terrainProviderChangedCallback = undefined;
    }

    // Shaders modified for clipping and for color don't get cached, so destroy these manually
    if (defined(this._cachedRendererResources)) {
      destroyIfNotCached(this._rendererResources, this._cachedRendererResources);
    }

    this._rendererResources = undefined;
    this._cachedRendererResources =
      this._cachedRendererResources && this._cachedRendererResources.release();
    DracoLoader.destroyCachedDataForModel(this);

    var pickIds = this._pickIds;
    var length = pickIds.length;
    for (var i = 0; i < length; ++i) {
      pickIds[i].destroy();
    }

    releaseCachedGltf(this);
    this._quantizedVertexShaders = undefined;

    // Only destroy the ClippingPlaneCollection if this is the owner - if this model is part of a Cesium3DTileset,
    // _clippingPlanes references a ClippingPlaneCollection that this model does not own.
    var clippingPlaneCollection = this._clippingPlanes;
    if (
      defined(clippingPlaneCollection) &&
      !clippingPlaneCollection.isDestroyed() &&
      clippingPlaneCollection.owner === this
    ) {
      clippingPlaneCollection.destroy();
    }
    this._clippingPlanes = undefined;

    this._specularEnvironmentMapAtlas =
      this._specularEnvironmentMapAtlas &&
      this._specularEnvironmentMapAtlas.destroy();

    return destroyObject(this);
  };

  // exposed for testing
  Model._getClippingFunction = getClippingFunction;
  Model._modifyShaderForColor = modifyShaderForColor;

  /**
   * Represents the contents of a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Batched3DModel|Batched 3D Model}
   * tile in a {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Batched3DModel3DTileContent
   * @constructor
   *
   * @private
   */
  function Batched3DModel3DTileContent(
    tileset,
    tile,
    resource,
    arrayBuffer,
    byteOffset
  ) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;
    this._model = undefined;
    this._batchTable = undefined;
    this._features = undefined;

    // Populate from gltf when available
    this._batchIdAttributeName = undefined;
    this._diffuseAttributeOrUniformName = {};

    this._rtcCenterTransform = undefined;
    this._contentModelMatrix = undefined;

    this.featurePropertiesDirty = false;

    initialize$2(this, arrayBuffer, byteOffset);
  }

  // This can be overridden for testing purposes
  Batched3DModel3DTileContent._deprecationWarning = deprecationWarning;

  Object.defineProperties(Batched3DModel3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        return this._batchTable.featuresLength;
      },
    },

    pointsLength: {
      get: function () {
        return 0;
      },
    },

    trianglesLength: {
      get: function () {
        return this._model.trianglesLength;
      },
    },

    geometryByteLength: {
      get: function () {
        return this._model.geometryByteLength;
      },
    },

    texturesByteLength: {
      get: function () {
        return this._model.texturesByteLength;
      },
    },

    batchTableByteLength: {
      get: function () {
        return this._batchTable.memorySizeInBytes;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return this._model.readyPromise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    batchTable: {
      get: function () {
        return this._batchTable;
      },
    },
  });

  var sizeOfUint32$3 = Uint32Array.BYTES_PER_ELEMENT;

  function getBatchIdAttributeName(gltf) {
    var batchIdAttributeName = ModelUtility.getAttributeOrUniformBySemantic(
      gltf,
      "_BATCHID"
    );
    if (!defined(batchIdAttributeName)) {
      batchIdAttributeName = ModelUtility.getAttributeOrUniformBySemantic(
        gltf,
        "BATCHID"
      );
      if (defined(batchIdAttributeName)) {
        Batched3DModel3DTileContent._deprecationWarning(
          "b3dm-legacy-batchid",
          "The glTF in this b3dm uses the semantic `BATCHID`. Application-specific semantics should be prefixed with an underscore: `_BATCHID`."
        );
      }
    }
    return batchIdAttributeName;
  }

  function getVertexShaderCallback(content) {
    return function (vs, programId) {
      var batchTable = content._batchTable;
      var handleTranslucent = !defined(content._tileset.classificationType);

      var gltf = content._model.gltf;
      if (defined(gltf)) {
        content._batchIdAttributeName = getBatchIdAttributeName(gltf);
        content._diffuseAttributeOrUniformName[
          programId
        ] = ModelUtility.getDiffuseAttributeOrUniform(gltf, programId);
      }

      var callback = batchTable.getVertexShaderCallback(
        handleTranslucent,
        content._batchIdAttributeName,
        content._diffuseAttributeOrUniformName[programId]
      );
      return defined(callback) ? callback(vs) : vs;
    };
  }

  function getFragmentShaderCallback(content) {
    return function (fs, programId) {
      var batchTable = content._batchTable;
      var handleTranslucent = !defined(content._tileset.classificationType);

      var gltf = content._model.gltf;
      if (defined(gltf)) {
        content._diffuseAttributeOrUniformName[
          programId
        ] = ModelUtility.getDiffuseAttributeOrUniform(gltf, programId);
      }
      var callback = batchTable.getFragmentShaderCallback(
        handleTranslucent,
        content._diffuseAttributeOrUniformName[programId]
      );
      return defined(callback) ? callback(fs) : fs;
    };
  }

  function getPickIdCallback(content) {
    return function () {
      return content._batchTable.getPickId();
    };
  }

  function getClassificationFragmentShaderCallback(content) {
    return function (fs) {
      var batchTable = content._batchTable;
      var callback = batchTable.getClassificationFragmentShaderCallback();
      return defined(callback) ? callback(fs) : fs;
    };
  }

  function createColorChangedCallback(content) {
    return function (batchId, color) {
      content._model.updateCommands(batchId, color);
    };
  }

  function initialize$2(content, arrayBuffer, byteOffset) {
    var tileset = content._tileset;
    var tile = content._tile;
    var resource = content._resource;

    var byteStart = defaultValue(byteOffset, 0);
    byteOffset = byteStart;

    var uint8Array = new Uint8Array(arrayBuffer);
    var view = new DataView(arrayBuffer);
    byteOffset += sizeOfUint32$3; // Skip magic

    var version = view.getUint32(byteOffset, true);
    if (version !== 1) {
      throw new RuntimeError(
        "Only Batched 3D Model version 1 is supported.  Version " +
          version +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$3;

    var byteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$3;

    var featureTableJsonByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$3;

    var featureTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$3;

    var batchTableJsonByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$3;

    var batchTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$3;

    var batchLength;

    // Legacy header #1: [batchLength] [batchTableByteLength]
    // Legacy header #2: [batchTableJsonByteLength] [batchTableBinaryByteLength] [batchLength]
    // Current header: [featureTableJsonByteLength] [featureTableBinaryByteLength] [batchTableJsonByteLength] [batchTableBinaryByteLength]
    // If the header is in the first legacy format 'batchTableJsonByteLength' will be the start of the JSON string (a quotation mark) or the glTF magic.
    // Accordingly its first byte will be either 0x22 or 0x67, and so the minimum uint32 expected is 0x22000000 = 570425344 = 570MB. It is unlikely that the feature table JSON will exceed this length.
    // The check for the second legacy format is similar, except it checks 'batchTableBinaryByteLength' instead
    if (batchTableJsonByteLength >= 570425344) {
      // First legacy check
      byteOffset -= sizeOfUint32$3 * 2;
      batchLength = featureTableJsonByteLength;
      batchTableJsonByteLength = featureTableBinaryByteLength;
      batchTableBinaryByteLength = 0;
      featureTableJsonByteLength = 0;
      featureTableBinaryByteLength = 0;
      Batched3DModel3DTileContent._deprecationWarning(
        "b3dm-legacy-header",
        "This b3dm header is using the legacy format [batchLength] [batchTableByteLength]. The new format is [featureTableJsonByteLength] [featureTableBinaryByteLength] [batchTableJsonByteLength] [batchTableBinaryByteLength] from https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Batched3DModel."
      );
    } else if (batchTableBinaryByteLength >= 570425344) {
      // Second legacy check
      byteOffset -= sizeOfUint32$3;
      batchLength = batchTableJsonByteLength;
      batchTableJsonByteLength = featureTableJsonByteLength;
      batchTableBinaryByteLength = featureTableBinaryByteLength;
      featureTableJsonByteLength = 0;
      featureTableBinaryByteLength = 0;
      Batched3DModel3DTileContent._deprecationWarning(
        "b3dm-legacy-header",
        "This b3dm header is using the legacy format [batchTableJsonByteLength] [batchTableBinaryByteLength] [batchLength]. The new format is [featureTableJsonByteLength] [featureTableBinaryByteLength] [batchTableJsonByteLength] [batchTableBinaryByteLength] from https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Batched3DModel."
      );
    }

    var featureTableJson;
    if (featureTableJsonByteLength === 0) {
      featureTableJson = {
        BATCH_LENGTH: defaultValue(batchLength, 0),
      };
    } else {
      var featureTableString = getStringFromTypedArray(
        uint8Array,
        byteOffset,
        featureTableJsonByteLength
      );
      featureTableJson = JSON.parse(featureTableString);
      byteOffset += featureTableJsonByteLength;
    }

    var featureTableBinary = new Uint8Array(
      arrayBuffer,
      byteOffset,
      featureTableBinaryByteLength
    );
    byteOffset += featureTableBinaryByteLength;

    var featureTable = new Cesium3DTileFeatureTable(
      featureTableJson,
      featureTableBinary
    );

    batchLength = featureTable.getGlobalProperty("BATCH_LENGTH");
    featureTable.featuresLength = batchLength;

    var batchTableJson;
    var batchTableBinary;
    if (batchTableJsonByteLength > 0) {
      // PERFORMANCE_IDEA: is it possible to allocate this on-demand?  Perhaps keep the
      // arraybuffer/string compressed in memory and then decompress it when it is first accessed.
      //
      // We could also make another request for it, but that would make the property set/get
      // API async, and would double the number of numbers in some cases.
      var batchTableString = getStringFromTypedArray(
        uint8Array,
        byteOffset,
        batchTableJsonByteLength
      );
      batchTableJson = JSON.parse(batchTableString);
      byteOffset += batchTableJsonByteLength;

      if (batchTableBinaryByteLength > 0) {
        // Has a batch table binary
        batchTableBinary = new Uint8Array(
          arrayBuffer,
          byteOffset,
          batchTableBinaryByteLength
        );
        // Copy the batchTableBinary section and let the underlying ArrayBuffer be freed
        batchTableBinary = new Uint8Array(batchTableBinary);
        byteOffset += batchTableBinaryByteLength;
      }
    }

    var colorChangedCallback;
    if (defined(tileset.classificationType)) {
      colorChangedCallback = createColorChangedCallback(content);
    }

    var batchTable = new Cesium3DTileBatchTable(
      content,
      batchLength,
      batchTableJson,
      batchTableBinary,
      colorChangedCallback
    );
    content._batchTable = batchTable;

    var gltfByteLength = byteStart + byteLength - byteOffset;
    if (gltfByteLength === 0) {
      throw new RuntimeError("glTF byte length must be greater than 0.");
    }

    var gltfView;
    if (byteOffset % 4 === 0) {
      gltfView = new Uint8Array(arrayBuffer, byteOffset, gltfByteLength);
    } else {
      // Create a copy of the glb so that it is 4-byte aligned
      Batched3DModel3DTileContent._deprecationWarning(
        "b3dm-glb-unaligned",
        "The embedded glb is not aligned to a 4-byte boundary."
      );
      gltfView = new Uint8Array(
        uint8Array.subarray(byteOffset, byteOffset + gltfByteLength)
      );
    }

    var pickObject = {
      content: content,
      primitive: tileset,
    };

    content._rtcCenterTransform = Matrix4.IDENTITY;
    var rtcCenter = featureTable.getGlobalProperty(
      "RTC_CENTER",
      ComponentDatatype$1.FLOAT,
      3
    );
    if (defined(rtcCenter)) {
      content._rtcCenterTransform = Matrix4.fromTranslation(
        Cartesian3.fromArray(rtcCenter)
      );
    }

    content._contentModelMatrix = Matrix4.multiply(
      tile.computedTransform,
      content._rtcCenterTransform,
      new Matrix4()
    );

    if (!defined(tileset.classificationType)) {
      // PERFORMANCE_IDEA: patch the shader on demand, e.g., the first time show/color changes.
      // The pick shader still needs to be patched.
      content._model = new Model({
        gltf: gltfView,
        cull: false, // The model is already culled by 3D Tiles
        releaseGltfJson: true, // Models are unique and will not benefit from caching so save memory
        opaquePass: Pass$1.CESIUM_3D_TILE, // Draw opaque portions of the model during the 3D Tiles pass
        basePath: resource,
        requestType: RequestType$1.TILES3D,
        modelMatrix: content._contentModelMatrix,
        upAxis: tileset._gltfUpAxis,
        forwardAxis: Axis$1.X,
        shadows: tileset.shadows,
        debugWireframe: tileset.debugWireframe,
        incrementallyLoadTextures: false,
        vertexShaderLoaded: getVertexShaderCallback(content),
        fragmentShaderLoaded: getFragmentShaderCallback(content),
        uniformMapLoaded: batchTable.getUniformMapCallback(),
        pickIdLoaded: getPickIdCallback(content),
        addBatchIdToGeneratedShaders: batchLength > 0, // If the batch table has values in it, generated shaders will need a batchId attribute
        pickObject: pickObject,
        imageBasedLightingFactor: tileset.imageBasedLightingFactor,
        lightColor: tileset.lightColor,
        luminanceAtZenith: tileset.luminanceAtZenith,
        sphericalHarmonicCoefficients: tileset.sphericalHarmonicCoefficients,
        specularEnvironmentMaps: tileset.specularEnvironmentMaps,
        backFaceCulling: tileset.backFaceCulling,
      });
      content._model.readyPromise.then(function (model) {
        model.activeAnimations.addAll({
          loop: ModelAnimationLoop$1.REPEAT,
        });
      });
    } else {
      // This transcodes glTF to an internal representation for geometry so we can take advantage of the re-batching of vector data.
      // For a list of limitations on the input glTF, see the documentation for classificationType of Cesium3DTileset.
      content._model = new ClassificationModel({
        gltf: gltfView,
        cull: false, // The model is already culled by 3D Tiles
        basePath: resource,
        requestType: RequestType$1.TILES3D,
        modelMatrix: content._contentModelMatrix,
        upAxis: tileset._gltfUpAxis,
        forwardAxis: Axis$1.X,
        debugWireframe: tileset.debugWireframe,
        vertexShaderLoaded: getVertexShaderCallback(content),
        classificationShaderLoaded: getClassificationFragmentShaderCallback(
          content
        ),
        uniformMapLoaded: batchTable.getUniformMapCallback(),
        pickIdLoaded: getPickIdCallback(content),
        classificationType: tileset._classificationType,
        batchTable: batchTable,
      });
    }
  }

  function createFeatures(content) {
    var featuresLength = content.featuresLength;
    if (!defined(content._features) && featuresLength > 0) {
      var features = new Array(featuresLength);
      for (var i = 0; i < featuresLength; ++i) {
        features[i] = new Cesium3DTileFeature(content, i);
      }
      content._features = features;
    }
  }

  Batched3DModel3DTileContent.prototype.hasProperty = function (batchId, name) {
    return this._batchTable.hasProperty(batchId, name);
  };

  Batched3DModel3DTileContent.prototype.getFeature = function (batchId) {
    //>>includeStart('debug', pragmas.debug);
    var featuresLength = this.featuresLength;
    if (!defined(batchId) || batchId < 0 || batchId >= featuresLength) {
      throw new DeveloperError(
        "batchId is required and between zero and featuresLength - 1 (" +
          (featuresLength - 1) +
          ")."
      );
    }
    //>>includeEnd('debug');

    createFeatures(this);
    return this._features[batchId];
  };

  Batched3DModel3DTileContent.prototype.applyDebugSettings = function (
    enabled,
    color
  ) {
    color = enabled ? color : Color.WHITE;
    if (this.featuresLength === 0) {
      this._model.color = color;
    } else {
      this._batchTable.setAllColor(color);
    }
  };

  Batched3DModel3DTileContent.prototype.applyStyle = function (style) {
    if (this.featuresLength === 0) {
      var hasColorStyle = defined(style) && defined(style.color);
      var hasShowStyle = defined(style) && defined(style.show);
      this._model.color = hasColorStyle
        ? style.color.evaluateColor(undefined, this._model.color)
        : Color.clone(Color.WHITE, this._model.color);
      this._model.show = hasShowStyle ? style.show.evaluate(undefined) : true;
    } else {
      this._batchTable.applyStyle(style);
    }
  };

  Batched3DModel3DTileContent.prototype.update = function (tileset, frameState) {
    var commandStart = frameState.commandList.length;

    // In the PROCESSING state we may be calling update() to move forward
    // the content's resource loading.  In the READY state, it will
    // actually generate commands.
    this._batchTable.update(tileset, frameState);

    this._contentModelMatrix = Matrix4.multiply(
      this._tile.computedTransform,
      this._rtcCenterTransform,
      this._contentModelMatrix
    );
    this._model.modelMatrix = this._contentModelMatrix;

    this._model.shadows = this._tileset.shadows;
    this._model.imageBasedLightingFactor = this._tileset.imageBasedLightingFactor;
    this._model.lightColor = this._tileset.lightColor;
    this._model.luminanceAtZenith = this._tileset.luminanceAtZenith;
    this._model.sphericalHarmonicCoefficients = this._tileset.sphericalHarmonicCoefficients;
    this._model.specularEnvironmentMaps = this._tileset.specularEnvironmentMaps;
    this._model.backFaceCulling = this._tileset.backFaceCulling;
    this._model.debugWireframe = this._tileset.debugWireframe;

    // Update clipping planes
    var tilesetClippingPlanes = this._tileset.clippingPlanes;
    this._model.clippingPlanesOriginMatrix = this._tileset.clippingPlanesOriginMatrix;
    if (defined(tilesetClippingPlanes) && this._tile.clippingPlanesDirty) {
      // Dereference the clipping planes from the model if they are irrelevant.
      // Link/Dereference directly to avoid ownership checks.
      // This will also trigger synchronous shader regeneration to remove or add the clipping plane and color blending code.
      this._model._clippingPlanes =
        tilesetClippingPlanes.enabled && this._tile._isClipped
          ? tilesetClippingPlanes
          : undefined;
    }

    // If the model references a different ClippingPlaneCollection due to the tileset's collection being replaced with a
    // ClippingPlaneCollection that gives this tile the same clipping status, update the model to use the new ClippingPlaneCollection.
    if (
      defined(tilesetClippingPlanes) &&
      defined(this._model._clippingPlanes) &&
      this._model._clippingPlanes !== tilesetClippingPlanes
    ) {
      this._model._clippingPlanes = tilesetClippingPlanes;
    }

    this._model.update(frameState);

    // If any commands were pushed, add derived commands
    var commandEnd = frameState.commandList.length;
    if (
      commandStart < commandEnd &&
      (frameState.passes.render || frameState.passes.pick) &&
      !defined(tileset.classificationType)
    ) {
      this._batchTable.addDerivedCommands(frameState, commandStart);
    }
  };

  Batched3DModel3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Batched3DModel3DTileContent.prototype.destroy = function () {
    this._model = this._model && this._model.destroy();
    this._batchTable = this._batchTable && this._batchTable.destroy();
    return destroyObject(this);
  };

  /**
   * Represents the contents of a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Composite|Composite}
   * tile in a {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Composite3DTileContent
   * @constructor
   *
   * @private
   */
  function Composite3DTileContent(
    tileset,
    tile,
    resource,
    arrayBuffer,
    byteOffset,
    factory
  ) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;
    this._contents = [];
    this._readyPromise = when.defer();

    initialize$3(this, arrayBuffer, byteOffset, factory);
  }

  Object.defineProperties(Composite3DTileContent.prototype, {
    featurePropertiesDirty: {
      get: function () {
        var contents = this._contents;
        var length = contents.length;
        for (var i = 0; i < length; ++i) {
          if (contents[i].featurePropertiesDirty) {
            return true;
          }
        }

        return false;
      },
      set: function (value) {
        var contents = this._contents;
        var length = contents.length;
        for (var i = 0; i < length; ++i) {
          contents[i].featurePropertiesDirty = value;
        }
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
     * always returns <code>0</code>.  Instead call <code>featuresLength</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    featuresLength: {
      get: function () {
        return 0;
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
     * always returns <code>0</code>.  Instead call <code>pointsLength</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    pointsLength: {
      get: function () {
        return 0;
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
     * always returns <code>0</code>.  Instead call <code>trianglesLength</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    trianglesLength: {
      get: function () {
        return 0;
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
     * always returns <code>0</code>.  Instead call <code>geometryByteLength</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    geometryByteLength: {
      get: function () {
        return 0;
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface.   <code>Composite3DTileContent</code>
     * always returns <code>0</code>.  Instead call <code>texturesByteLength</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    texturesByteLength: {
      get: function () {
        return 0;
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
     * always returns <code>0</code>.  Instead call <code>batchTableByteLength</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    batchTableByteLength: {
      get: function () {
        return 0;
      },
    },

    innerContents: {
      get: function () {
        return this._contents;
      },
    },

    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    /**
     * Part of the {@link Cesium3DTileContent} interface. <code>Composite3DTileContent</code>
     * always returns <code>undefined</code>.  Instead call <code>batchTable</code> for a tile in the composite.
     * @memberof Composite3DTileContent.prototype
     */
    batchTable: {
      get: function () {
        return undefined;
      },
    },
  });

  var sizeOfUint32$4 = Uint32Array.BYTES_PER_ELEMENT;

  function initialize$3(content, arrayBuffer, byteOffset, factory) {
    byteOffset = defaultValue(byteOffset, 0);

    var uint8Array = new Uint8Array(arrayBuffer);
    var view = new DataView(arrayBuffer);
    byteOffset += sizeOfUint32$4; // Skip magic

    var version = view.getUint32(byteOffset, true);
    if (version !== 1) {
      throw new RuntimeError(
        "Only Composite Tile version 1 is supported. Version " +
          version +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$4;

    // Skip byteLength
    byteOffset += sizeOfUint32$4;

    var tilesLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$4;

    var contentPromises = [];

    for (var i = 0; i < tilesLength; ++i) {
      var tileType = getMagic(uint8Array, byteOffset);

      // Tile byte length is stored after magic and version
      var tileByteLength = view.getUint32(byteOffset + sizeOfUint32$4 * 2, true);

      var contentFactory = factory[tileType];

      if (defined(contentFactory)) {
        var innerContent = contentFactory(
          content._tileset,
          content._tile,
          content._resource,
          arrayBuffer,
          byteOffset
        );
        content._contents.push(innerContent);
        contentPromises.push(innerContent.readyPromise);
      } else {
        throw new RuntimeError(
          "Unknown tile content type, " + tileType + ", inside Composite tile"
        );
      }

      byteOffset += tileByteLength;
    }

    when
      .all(contentPromises)
      .then(function () {
        content._readyPromise.resolve(content);
      })
      .otherwise(function (error) {
        content._readyPromise.reject(error);
      });
  }

  /**
   * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
   * always returns <code>false</code>.  Instead call <code>hasProperty</code> for a tile in the composite.
   */
  Composite3DTileContent.prototype.hasProperty = function (batchId, name) {
    return false;
  };

  /**
   * Part of the {@link Cesium3DTileContent} interface.  <code>Composite3DTileContent</code>
   * always returns <code>undefined</code>.  Instead call <code>getFeature</code> for a tile in the composite.
   */
  Composite3DTileContent.prototype.getFeature = function (batchId) {
    return undefined;
  };

  Composite3DTileContent.prototype.applyDebugSettings = function (
    enabled,
    color
  ) {
    var contents = this._contents;
    var length = contents.length;
    for (var i = 0; i < length; ++i) {
      contents[i].applyDebugSettings(enabled, color);
    }
  };

  Composite3DTileContent.prototype.applyStyle = function (style) {
    var contents = this._contents;
    var length = contents.length;
    for (var i = 0; i < length; ++i) {
      contents[i].applyStyle(style);
    }
  };

  Composite3DTileContent.prototype.update = function (tileset, frameState) {
    var contents = this._contents;
    var length = contents.length;
    for (var i = 0; i < length; ++i) {
      contents[i].update(tileset, frameState);
    }
  };

  Composite3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Composite3DTileContent.prototype.destroy = function () {
    var contents = this._contents;
    var length = contents.length;
    for (var i = 0; i < length; ++i) {
      contents[i].destroy();
    }
    return destroyObject(this);
  };

  /**
   * Creates a batch of box, cylinder, ellipsoid and/or sphere geometries intersecting terrain or 3D Tiles.
   *
   * @alias Vector3DTileGeometry
   * @constructor
   *
   * @param {Object} options An object with following properties:
   * @param {Float32Array} [options.boxes] The boxes in the tile.
   * @param {Uint16Array} [options.boxBatchIds] The batch ids for each box.
   * @param {Float32Array} [options.cylinders] The cylinders in the tile.
   * @param {Uint16Array} [options.cylinderBatchIds] The batch ids for each cylinder.
   * @param {Float32Array} [options.ellipsoids] The ellipsoids in the tile.
   * @param {Uint16Array} [options.ellipsoidBatchIds] The batch ids for each ellipsoid.
   * @param {Float32Array} [options.spheres] The spheres in the tile.
   * @param {Uint16Array} [options.sphereBatchIds] The batch ids for each sphere.
   * @param {Cartesian3} options.center The RTC center of all geometries.
   * @param {Matrix4} options.modelMatrix The model matrix of all geometries. Applied after the individual geometry model matrices.
   * @param {Cesium3DTileBatchTable} options.batchTable The batch table.
   * @param {BoundingSphere} options.boundingVolume The bounding volume containing all of the geometry in the tile.
   *
   * @private
   */
  function Vector3DTileGeometry(options) {
    // these will all be released after the primitive is created
    this._boxes = options.boxes;
    this._boxBatchIds = options.boxBatchIds;
    this._cylinders = options.cylinders;
    this._cylinderBatchIds = options.cylinderBatchIds;
    this._ellipsoids = options.ellipsoids;
    this._ellipsoidBatchIds = options.ellipsoidBatchIds;
    this._spheres = options.spheres;
    this._sphereBatchIds = options.sphereBatchIds;
    this._modelMatrix = options.modelMatrix;
    this._batchTable = options.batchTable;
    this._boundingVolume = options.boundingVolume;

    this._center = options.center;
    if (!defined(this._center)) {
      if (defined(this._boundingVolume)) {
        this._center = Cartesian3.clone(this._boundingVolume.center);
      } else {
        this._center = Cartesian3.clone(Cartesian3.ZERO);
      }
    }

    this._boundingVolumes = undefined;
    this._batchedIndices = undefined;

    this._indices = undefined;
    this._indexOffsets = undefined;
    this._indexCounts = undefined;

    this._positions = undefined;
    this._vertexBatchIds = undefined;

    this._batchIds = undefined;

    this._batchTableColors = undefined;
    this._packedBuffer = undefined;

    this._ready = false;
    this._readyPromise = when.defer();

    this._verticesPromise = undefined;

    this._primitive = undefined;

    /**
     * Draws the wireframe of the classification geometries.
     * @type {Boolean}
     * @default false
     */
    this.debugWireframe = false;

    /**
     * Forces a re-batch instead of waiting after a number of frames have been rendered. For testing only.
     * @type {Boolean}
     * @default false
     */
    this.forceRebatch = false;

    /**
     * What this tile will classify.
     * @type {ClassificationType}
     * @default ClassificationType.BOTH
     */
    this.classificationType = ClassificationType$1.BOTH;
  }

  Object.defineProperties(Vector3DTileGeometry.prototype, {
    /**
     * Gets the number of triangles.
     *
     * @memberof Vector3DTileGeometry.prototype
     *
     * @type {Number}
     * @readonly
     */
    trianglesLength: {
      get: function () {
        if (defined(this._primitive)) {
          return this._primitive.trianglesLength;
        }
        return 0;
      },
    },

    /**
     * Gets the geometry memory in bytes.
     *
     * @memberof Vector3DTileGeometry.prototype
     *
     * @type {Number}
     * @readonly
     */
    geometryByteLength: {
      get: function () {
        if (defined(this._primitive)) {
          return this._primitive.geometryByteLength;
        }
        return 0;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof Vector3DTileGeometry.prototype
     * @type {Promise<void>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  Vector3DTileGeometry.packedBoxLength =
    Matrix4.packedLength + Cartesian3.packedLength;
  Vector3DTileGeometry.packedCylinderLength = Matrix4.packedLength + 2;
  Vector3DTileGeometry.packedEllipsoidLength =
    Matrix4.packedLength + Cartesian3.packedLength;
  Vector3DTileGeometry.packedSphereLength = Cartesian3.packedLength + 1;

  function packBuffer(geometries) {
    var packedBuffer = new Float64Array(
      Matrix4.packedLength + Cartesian3.packedLength
    );

    var offset = 0;
    Cartesian3.pack(geometries._center, packedBuffer, offset);
    offset += Cartesian3.packedLength;
    Matrix4.pack(geometries._modelMatrix, packedBuffer, offset);

    return packedBuffer;
  }

  function unpackBuffer(geometries, packedBuffer) {
    var offset = 0;

    var indicesBytesPerElement = packedBuffer[offset++];
    var numBVS = packedBuffer[offset++];
    var bvs = (geometries._boundingVolumes = new Array(numBVS));

    for (var i = 0; i < numBVS; ++i) {
      bvs[i] = BoundingSphere.unpack(packedBuffer, offset);
      offset += BoundingSphere.packedLength;
    }

    var numBatchedIndices = packedBuffer[offset++];
    var bis = (geometries._batchedIndices = new Array(numBatchedIndices));

    for (var j = 0; j < numBatchedIndices; ++j) {
      var color = Color.unpack(packedBuffer, offset);
      offset += Color.packedLength;

      var indexOffset = packedBuffer[offset++];
      var count = packedBuffer[offset++];

      var length = packedBuffer[offset++];
      var batchIds = new Array(length);

      for (var k = 0; k < length; ++k) {
        batchIds[k] = packedBuffer[offset++];
      }

      bis[j] = new Vector3DTileBatch({
        color: color,
        offset: indexOffset,
        count: count,
        batchIds: batchIds,
      });
    }

    return indicesBytesPerElement;
  }

  var createVerticesTaskProcessor = new TaskProcessor(
    "createVectorTileGeometries"
  );
  var scratchColor$4 = new Color();

  function createPrimitive$1(geometries) {
    if (defined(geometries._primitive)) {
      return;
    }

    if (!defined(geometries._verticesPromise)) {
      var boxes = geometries._boxes;
      var boxBatchIds = geometries._boxBatchIds;
      var cylinders = geometries._cylinders;
      var cylinderBatchIds = geometries._cylinderBatchIds;
      var ellipsoids = geometries._ellipsoids;
      var ellipsoidBatchIds = geometries._ellipsoidBatchIds;
      var spheres = geometries._spheres;
      var sphereBatchIds = geometries._sphereBatchIds;

      var batchTableColors = geometries._batchTableColors;
      var packedBuffer = geometries._packedBuffer;

      if (!defined(batchTableColors)) {
        // Copy because they may be the views on the same buffer.
        var length = 0;
        if (defined(geometries._boxes)) {
          boxes = geometries._boxes = arraySlice(boxes);
          boxBatchIds = geometries._boxBatchIds = arraySlice(boxBatchIds);
          length += boxBatchIds.length;
        }
        if (defined(geometries._cylinders)) {
          cylinders = geometries._cylinders = arraySlice(cylinders);
          cylinderBatchIds = geometries._cylinderBatchIds = arraySlice(
            cylinderBatchIds
          );
          length += cylinderBatchIds.length;
        }
        if (defined(geometries._ellipsoids)) {
          ellipsoids = geometries._ellipsoids = arraySlice(ellipsoids);
          ellipsoidBatchIds = geometries._ellipsoidBatchIds = arraySlice(
            ellipsoidBatchIds
          );
          length += ellipsoidBatchIds.length;
        }
        if (defined(geometries._spheres)) {
          spheres = geometries._sphere = arraySlice(spheres);
          sphereBatchIds = geometries._sphereBatchIds = arraySlice(
            sphereBatchIds
          );
          length += sphereBatchIds.length;
        }

        batchTableColors = geometries._batchTableColors = new Uint32Array(length);
        var batchTable = geometries._batchTable;

        for (var i = 0; i < length; ++i) {
          var color = batchTable.getColor(i, scratchColor$4);
          batchTableColors[i] = color.toRgba();
        }

        packedBuffer = geometries._packedBuffer = packBuffer(geometries);
      }

      var transferrableObjects = [];
      if (defined(boxes)) {
        transferrableObjects.push(boxes.buffer, boxBatchIds.buffer);
      }
      if (defined(cylinders)) {
        transferrableObjects.push(cylinders.buffer, cylinderBatchIds.buffer);
      }
      if (defined(ellipsoids)) {
        transferrableObjects.push(ellipsoids.buffer, ellipsoidBatchIds.buffer);
      }
      if (defined(spheres)) {
        transferrableObjects.push(spheres.buffer, sphereBatchIds.buffer);
      }
      transferrableObjects.push(batchTableColors.buffer, packedBuffer.buffer);

      var parameters = {
        boxes: defined(boxes) ? boxes.buffer : undefined,
        boxBatchIds: defined(boxes) ? boxBatchIds.buffer : undefined,
        cylinders: defined(cylinders) ? cylinders.buffer : undefined,
        cylinderBatchIds: defined(cylinders)
          ? cylinderBatchIds.buffer
          : undefined,
        ellipsoids: defined(ellipsoids) ? ellipsoids.buffer : undefined,
        ellipsoidBatchIds: defined(ellipsoids)
          ? ellipsoidBatchIds.buffer
          : undefined,
        spheres: defined(spheres) ? spheres.buffer : undefined,
        sphereBatchIds: defined(spheres) ? sphereBatchIds.buffer : undefined,
        batchTableColors: batchTableColors.buffer,
        packedBuffer: packedBuffer.buffer,
      };

      var verticesPromise = (geometries._verticesPromise = createVerticesTaskProcessor.scheduleTask(
        parameters,
        transferrableObjects
      ));
      if (!defined(verticesPromise)) {
        // Postponed
        return;
      }

      verticesPromise.then(function (result) {
        var packedBuffer = new Float64Array(result.packedBuffer);
        var indicesBytesPerElement = unpackBuffer(geometries, packedBuffer);

        if (indicesBytesPerElement === 2) {
          geometries._indices = new Uint16Array(result.indices);
        } else {
          geometries._indices = new Uint32Array(result.indices);
        }

        geometries._indexOffsets = new Uint32Array(result.indexOffsets);
        geometries._indexCounts = new Uint32Array(result.indexCounts);

        geometries._positions = new Float32Array(result.positions);
        geometries._vertexBatchIds = new Uint16Array(result.vertexBatchIds);

        geometries._batchIds = new Uint16Array(result.batchIds);

        geometries._ready = true;
      });
    }

    if (geometries._ready && !defined(geometries._primitive)) {
      geometries._primitive = new Vector3DTilePrimitive({
        batchTable: geometries._batchTable,
        positions: geometries._positions,
        batchIds: geometries._batchIds,
        vertexBatchIds: geometries._vertexBatchIds,
        indices: geometries._indices,
        indexOffsets: geometries._indexOffsets,
        indexCounts: geometries._indexCounts,
        batchedIndices: geometries._batchedIndices,
        boundingVolume: geometries._boundingVolume,
        boundingVolumes: geometries._boundingVolumes,
        center: geometries._center,
        pickObject: defaultValue(geometries._pickObject, geometries),
      });

      geometries._boxes = undefined;
      geometries._boxBatchIds = undefined;
      geometries._cylinders = undefined;
      geometries._cylinderBatchIds = undefined;
      geometries._ellipsoids = undefined;
      geometries._ellipsoidBatchIds = undefined;
      geometries._spheres = undefined;
      geometries._sphereBatchIds = undefined;
      geometries._center = undefined;
      geometries._modelMatrix = undefined;
      geometries._batchTable = undefined;
      geometries._boundingVolume = undefined;

      geometries._boundingVolumes = undefined;
      geometries._batchedIndices = undefined;

      geometries._indices = undefined;
      geometries._indexOffsets = undefined;
      geometries._indexCounts = undefined;

      geometries._positions = undefined;
      geometries._vertexBatchIds = undefined;

      geometries._batchIds = undefined;

      geometries._batchTableColors = undefined;
      geometries._packedBuffer = undefined;

      geometries._verticesPromise = undefined;

      geometries._readyPromise.resolve();
    }
  }

  /**
   * Creates features for each geometry and places it at the batch id index of features.
   *
   * @param {Vector3DTileContent} content The vector tile content.
   * @param {Cesium3DTileFeature[]} features An array of features where the polygon features will be placed.
   */
  Vector3DTileGeometry.prototype.createFeatures = function (content, features) {
    this._primitive.createFeatures(content, features);
  };

  /**
   * Colors the entire tile when enabled is true. The resulting color will be (geometry batch table color * color).
   *
   * @param {Boolean} enabled Whether to enable debug coloring.
   * @param {Color} color The debug color.
   */
  Vector3DTileGeometry.prototype.applyDebugSettings = function (enabled, color) {
    this._primitive.applyDebugSettings(enabled, color);
  };

  /**
   * Apply a style to the content.
   *
   * @param {Cesium3DTileStyle} style The style.
   * @param {Cesium3DTileFeature[]} features The array of features.
   */
  Vector3DTileGeometry.prototype.applyStyle = function (style, features) {
    this._primitive.applyStyle(style, features);
  };

  /**
   * Call when updating the color of a geometry with batchId changes color. The geometries will need to be re-batched
   * on the next update.
   *
   * @param {Number} batchId The batch id of the geometries whose color has changed.
   * @param {Color} color The new polygon color.
   */
  Vector3DTileGeometry.prototype.updateCommands = function (batchId, color) {
    this._primitive.updateCommands(batchId, color);
  };

  /**
   * Updates the batches and queues the commands for rendering.
   *
   * @param {FrameState} frameState The current frame state.
   */
  Vector3DTileGeometry.prototype.update = function (frameState) {
    createPrimitive$1(this);

    if (!this._ready) {
      return;
    }

    this._primitive.debugWireframe = this.debugWireframe;
    this._primitive.forceRebatch = this.forceRebatch;
    this._primitive.classificationType = this.classificationType;
    this._primitive.update(frameState);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  Vector3DTileGeometry.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  Vector3DTileGeometry.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    return destroyObject(this);
  };

  /**
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Geometry3DTileContent
   * @constructor
   *
   * @private
   */
  function Geometry3DTileContent(
    tileset,
    tile,
    resource,
    arrayBuffer,
    byteOffset
  ) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;
    this._geometries = undefined;

    this._contentReadyPromise = undefined;
    this._readyPromise = when.defer();

    this._batchTable = undefined;
    this._features = undefined;

    /**
     * Part of the {@link Cesium3DTileContent} interface.
     */
    this.featurePropertiesDirty = false;

    initialize$4(this, arrayBuffer, byteOffset);
  }

  Object.defineProperties(Geometry3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        return defined(this._batchTable) ? this._batchTable.featuresLength : 0;
      },
    },

    pointsLength: {
      get: function () {
        return 0;
      },
    },

    trianglesLength: {
      get: function () {
        if (defined(this._geometries)) {
          return this._geometries.trianglesLength;
        }
        return 0;
      },
    },

    geometryByteLength: {
      get: function () {
        if (defined(this._geometries)) {
          return this._geometries.geometryByteLength;
        }
        return 0;
      },
    },

    texturesByteLength: {
      get: function () {
        return 0;
      },
    },

    batchTableByteLength: {
      get: function () {
        return defined(this._batchTable) ? this._batchTable.memorySizeInBytes : 0;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    batchTable: {
      get: function () {
        return this._batchTable;
      },
    },
  });

  function createColorChangedCallback$1(content) {
    return function (batchId, color) {
      if (defined(content._geometries)) {
        content._geometries.updateCommands(batchId, color);
      }
    };
  }

  function getBatchIds(featureTableJson, featureTableBinary) {
    var boxBatchIds;
    var cylinderBatchIds;
    var ellipsoidBatchIds;
    var sphereBatchIds;
    var i;

    var numberOfBoxes = defaultValue(featureTableJson.BOXES_LENGTH, 0);
    var numberOfCylinders = defaultValue(featureTableJson.CYLINDERS_LENGTH, 0);
    var numberOfEllipsoids = defaultValue(featureTableJson.ELLIPSOIDS_LENGTH, 0);
    var numberOfSpheres = defaultValue(featureTableJson.SPHERES_LENGTH, 0);

    if (numberOfBoxes > 0 && defined(featureTableJson.BOX_BATCH_IDS)) {
      var boxBatchIdsByteOffset =
        featureTableBinary.byteOffset + featureTableJson.BOX_BATCH_IDS.byteOffset;
      boxBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        boxBatchIdsByteOffset,
        numberOfBoxes
      );
    }

    if (numberOfCylinders > 0 && defined(featureTableJson.CYLINDER_BATCH_IDS)) {
      var cylinderBatchIdsByteOffset =
        featureTableBinary.byteOffset +
        featureTableJson.CYLINDER_BATCH_IDS.byteOffset;
      cylinderBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        cylinderBatchIdsByteOffset,
        numberOfCylinders
      );
    }

    if (numberOfEllipsoids > 0 && defined(featureTableJson.ELLIPSOID_BATCH_IDS)) {
      var ellipsoidBatchIdsByteOffset =
        featureTableBinary.byteOffset +
        featureTableJson.ELLIPSOID_BATCH_IDS.byteOffset;
      ellipsoidBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        ellipsoidBatchIdsByteOffset,
        numberOfEllipsoids
      );
    }

    if (numberOfSpheres > 0 && defined(featureTableJson.SPHERE_BATCH_IDS)) {
      var sphereBatchIdsByteOffset =
        featureTableBinary.byteOffset +
        featureTableJson.SPHERE_BATCH_IDS.byteOffset;
      sphereBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        sphereBatchIdsByteOffset,
        numberOfSpheres
      );
    }

    var atLeastOneDefined =
      defined(boxBatchIds) ||
      defined(cylinderBatchIds) ||
      defined(ellipsoidBatchIds) ||
      defined(sphereBatchIds);
    var atLeastOneUndefined =
      (numberOfBoxes > 0 && !defined(boxBatchIds)) ||
      (numberOfCylinders > 0 && !defined(cylinderBatchIds)) ||
      (numberOfEllipsoids > 0 && !defined(ellipsoidBatchIds)) ||
      (numberOfSpheres > 0 && !defined(sphereBatchIds));

    if (atLeastOneDefined && atLeastOneUndefined) {
      throw new RuntimeError(
        "If one group of batch ids is defined, then all batch ids must be defined."
      );
    }

    var allUndefinedBatchIds =
      !defined(boxBatchIds) &&
      !defined(cylinderBatchIds) &&
      !defined(ellipsoidBatchIds) &&
      !defined(sphereBatchIds);
    if (allUndefinedBatchIds) {
      var id = 0;
      if (!defined(boxBatchIds) && numberOfBoxes > 0) {
        boxBatchIds = new Uint16Array(numberOfBoxes);
        for (i = 0; i < numberOfBoxes; ++i) {
          boxBatchIds[i] = id++;
        }
      }
      if (!defined(cylinderBatchIds) && numberOfCylinders > 0) {
        cylinderBatchIds = new Uint16Array(numberOfCylinders);
        for (i = 0; i < numberOfCylinders; ++i) {
          cylinderBatchIds[i] = id++;
        }
      }
      if (!defined(ellipsoidBatchIds) && numberOfEllipsoids > 0) {
        ellipsoidBatchIds = new Uint16Array(numberOfEllipsoids);
        for (i = 0; i < numberOfEllipsoids; ++i) {
          ellipsoidBatchIds[i] = id++;
        }
      }
      if (!defined(sphereBatchIds) && numberOfSpheres > 0) {
        sphereBatchIds = new Uint16Array(numberOfSpheres);
        for (i = 0; i < numberOfSpheres; ++i) {
          sphereBatchIds[i] = id++;
        }
      }
    }

    return {
      boxes: boxBatchIds,
      cylinders: cylinderBatchIds,
      ellipsoids: ellipsoidBatchIds,
      spheres: sphereBatchIds,
    };
  }

  var sizeOfUint32$5 = Uint32Array.BYTES_PER_ELEMENT;

  function initialize$4(content, arrayBuffer, byteOffset) {
    byteOffset = defaultValue(byteOffset, 0);

    var uint8Array = new Uint8Array(arrayBuffer);
    var view = new DataView(arrayBuffer);
    byteOffset += sizeOfUint32$5; // Skip magic number

    var version = view.getUint32(byteOffset, true);
    if (version !== 1) {
      throw new RuntimeError(
        "Only Geometry tile version 1 is supported.  Version " +
          version +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$5;

    var byteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$5;

    if (byteLength === 0) {
      content._readyPromise.resolve(content);
      return;
    }

    var featureTableJSONByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$5;

    if (featureTableJSONByteLength === 0) {
      throw new RuntimeError(
        "Feature table must have a byte length greater than zero"
      );
    }

    var featureTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$5;
    var batchTableJSONByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$5;
    var batchTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$5;

    var featureTableString = getStringFromTypedArray(
      uint8Array,
      byteOffset,
      featureTableJSONByteLength
    );
    var featureTableJson = JSON.parse(featureTableString);
    byteOffset += featureTableJSONByteLength;

    var featureTableBinary = new Uint8Array(
      arrayBuffer,
      byteOffset,
      featureTableBinaryByteLength
    );
    byteOffset += featureTableBinaryByteLength;

    var batchTableJson;
    var batchTableBinary;
    if (batchTableJSONByteLength > 0) {
      // PERFORMANCE_IDEA: is it possible to allocate this on-demand?  Perhaps keep the
      // arraybuffer/string compressed in memory and then decompress it when it is first accessed.
      //
      // We could also make another request for it, but that would make the property set/get
      // API async, and would double the number of numbers in some cases.
      var batchTableString = getStringFromTypedArray(
        uint8Array,
        byteOffset,
        batchTableJSONByteLength
      );
      batchTableJson = JSON.parse(batchTableString);
      byteOffset += batchTableJSONByteLength;

      if (batchTableBinaryByteLength > 0) {
        // Has a batch table binary
        batchTableBinary = new Uint8Array(
          arrayBuffer,
          byteOffset,
          batchTableBinaryByteLength
        );
        // Copy the batchTableBinary section and let the underlying ArrayBuffer be freed
        batchTableBinary = new Uint8Array(batchTableBinary);
      }
    }

    var numberOfBoxes = defaultValue(featureTableJson.BOXES_LENGTH, 0);
    var numberOfCylinders = defaultValue(featureTableJson.CYLINDERS_LENGTH, 0);
    var numberOfEllipsoids = defaultValue(featureTableJson.ELLIPSOIDS_LENGTH, 0);
    var numberOfSpheres = defaultValue(featureTableJson.SPHERES_LENGTH, 0);

    var totalPrimitives =
      numberOfBoxes + numberOfCylinders + numberOfEllipsoids + numberOfSpheres;

    var batchTable = new Cesium3DTileBatchTable(
      content,
      totalPrimitives,
      batchTableJson,
      batchTableBinary,
      createColorChangedCallback$1(content)
    );
    content._batchTable = batchTable;

    if (totalPrimitives === 0) {
      return;
    }

    var modelMatrix = content.tile.computedTransform;

    var center;
    if (defined(featureTableJson.RTC_CENTER)) {
      center = Cartesian3.unpack(featureTableJson.RTC_CENTER);
      Matrix4.multiplyByPoint(modelMatrix, center, center);
    }

    var batchIds = getBatchIds(featureTableJson, featureTableBinary);

    if (
      numberOfBoxes > 0 ||
      numberOfCylinders > 0 ||
      numberOfEllipsoids > 0 ||
      numberOfSpheres > 0
    ) {
      var boxes;
      var cylinders;
      var ellipsoids;
      var spheres;

      if (numberOfBoxes > 0) {
        var boxesByteOffset =
          featureTableBinary.byteOffset + featureTableJson.BOXES.byteOffset;
        boxes = new Float32Array(
          featureTableBinary.buffer,
          boxesByteOffset,
          Vector3DTileGeometry.packedBoxLength * numberOfBoxes
        );
      }

      if (numberOfCylinders > 0) {
        var cylindersByteOffset =
          featureTableBinary.byteOffset + featureTableJson.CYLINDERS.byteOffset;
        cylinders = new Float32Array(
          featureTableBinary.buffer,
          cylindersByteOffset,
          Vector3DTileGeometry.packedCylinderLength * numberOfCylinders
        );
      }

      if (numberOfEllipsoids > 0) {
        var ellipsoidsByteOffset =
          featureTableBinary.byteOffset + featureTableJson.ELLIPSOIDS.byteOffset;
        ellipsoids = new Float32Array(
          featureTableBinary.buffer,
          ellipsoidsByteOffset,
          Vector3DTileGeometry.packedEllipsoidLength * numberOfEllipsoids
        );
      }

      if (numberOfSpheres > 0) {
        var spheresByteOffset =
          featureTableBinary.byteOffset + featureTableJson.SPHERES.byteOffset;
        spheres = new Float32Array(
          featureTableBinary.buffer,
          spheresByteOffset,
          Vector3DTileGeometry.packedSphereLength * numberOfSpheres
        );
      }

      content._geometries = new Vector3DTileGeometry({
        boxes: boxes,
        boxBatchIds: batchIds.boxes,
        cylinders: cylinders,
        cylinderBatchIds: batchIds.cylinders,
        ellipsoids: ellipsoids,
        ellipsoidBatchIds: batchIds.ellipsoids,
        spheres: spheres,
        sphereBatchIds: batchIds.spheres,
        center: center,
        modelMatrix: modelMatrix,
        batchTable: batchTable,
        boundingVolume: content.tile.boundingVolume.boundingVolume,
      });
    }
  }

  function createFeatures$1(content) {
    var featuresLength = content.featuresLength;
    if (!defined(content._features) && featuresLength > 0) {
      var features = new Array(featuresLength);
      if (defined(content._geometries)) {
        content._geometries.createFeatures(content, features);
      }
      content._features = features;
    }
  }

  Geometry3DTileContent.prototype.hasProperty = function (batchId, name) {
    return this._batchTable.hasProperty(batchId, name);
  };

  Geometry3DTileContent.prototype.getFeature = function (batchId) {
    //>>includeStart('debug', pragmas.debug);
    var featuresLength = this.featuresLength;
    if (!defined(batchId) || batchId < 0 || batchId >= featuresLength) {
      throw new DeveloperError(
        "batchId is required and between zero and featuresLength - 1 (" +
          (featuresLength - 1) +
          ")."
      );
    }
    //>>includeEnd('debug');

    createFeatures$1(this);
    return this._features[batchId];
  };

  Geometry3DTileContent.prototype.applyDebugSettings = function (enabled, color) {
    if (defined(this._geometries)) {
      this._geometries.applyDebugSettings(enabled, color);
    }
  };

  Geometry3DTileContent.prototype.applyStyle = function (style) {
    createFeatures$1(this);
    if (defined(this._geometries)) {
      this._geometries.applyStyle(style, this._features);
    }
  };

  Geometry3DTileContent.prototype.update = function (tileset, frameState) {
    if (defined(this._geometries)) {
      this._geometries.classificationType = this._tileset.classificationType;
      this._geometries.debugWireframe = this._tileset.debugWireframe;
      this._geometries.update(frameState);
    }
    if (defined(this._batchTable) && this._geometries._ready) {
      this._batchTable.update(tileset, frameState);
    }

    if (!defined(this._contentReadyPromise)) {
      var that = this;
      this._contentReadyPromise = this._geometries.readyPromise.then(function () {
        that._readyPromise.resolve(that);
      });
    }
  };

  Geometry3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Geometry3DTileContent.prototype.destroy = function () {
    this._geometries = this._geometries && this._geometries.destroy();
    this._batchTable = this._batchTable && this._batchTable.destroy();
    return destroyObject(this);
  };

  /**
   * @private
   */
  function ModelInstance(collection, modelMatrix, instanceId) {
    this.primitive = collection;
    this._modelMatrix = Matrix4.clone(modelMatrix);
    this._instanceId = instanceId;
  }

  Object.defineProperties(ModelInstance.prototype, {
    instanceId: {
      get: function () {
        return this._instanceId;
      },
    },
    model: {
      get: function () {
        return this.primitive._model;
      },
    },
    modelMatrix: {
      get: function () {
        return Matrix4.clone(this._modelMatrix);
      },
      set: function (value) {
        Matrix4.clone(value, this._modelMatrix);
        this.primitive.expandBoundingSphere(this._modelMatrix);
        this.primitive._dirty = true;
      },
    },
  });

  var LoadState = {
    NEEDS_LOAD: 0,
    LOADING: 1,
    LOADED: 2,
    FAILED: 3,
  };

  /**
   * A 3D model instance collection. All instances reference the same underlying model, but have unique
   * per-instance properties like model matrix, pick id, etc.
   *
   * Instances are rendered relative-to-center and for best results instances should be positioned close to one another.
   * Otherwise there may be precision issues if, for example, instances are placed on opposite sides of the globe.
   *
   * @alias ModelInstanceCollection
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Object[]} [options.instances] An array of instances, where each instance contains a modelMatrix and optional batchId when options.batchTable is defined.
   * @param {Cesium3DTileBatchTable} [options.batchTable] The batch table of the instanced 3D Tile.
   * @param {Resource|String} [options.url] The url to the .gltf file.
   * @param {Object} [options.requestType] The request type, used for request prioritization
   * @param {Object|ArrayBuffer|Uint8Array} [options.gltf] A glTF JSON object, or a binary glTF buffer.
   * @param {Resource|String} [options.basePath=''] The base path that paths in the glTF JSON are relative to.
   * @param {Boolean} [options.dynamic=false] Hint if instance model matrices will be updated frequently.
   * @param {Boolean} [options.show=true] Determines if the collection will be shown.
   * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each instance is pickable with {@link Scene#pick}.
   * @param {Boolean} [options.asynchronous=true] Determines if model WebGL resource creation will be spread out over several frames or block until completion once all glTF files are loaded.
   * @param {Boolean} [options.incrementallyLoadTextures=true] Determine if textures may continue to stream in after the model is loaded.
   * @param {ShadowMode} [options.shadows=ShadowMode.ENABLED] Determines whether the collection casts or receives shadows from light sources.
   * @param {Cartesian2} [options.imageBasedLightingFactor=new Cartesian2(1.0, 1.0)] Scales the diffuse and specular image-based lighting from the earth, sky, atmosphere and star skybox.
   * @param {Cartesian3} [options.lightColor] The light color when shading models. When <code>undefined</code> the scene's light color is used instead.
   * @param {Number} [options.luminanceAtZenith=0.2] The sun's luminance at the zenith in kilo candela per meter squared to use for this model's procedural environment map.
   * @param {Cartesian3[]} [options.sphericalHarmonicCoefficients] The third order spherical harmonic coefficients used for the diffuse color of image-based lighting.
   * @param {String} [options.specularEnvironmentMaps] A URL to a KTX file that contains a cube map of the specular lighting and the convoluted specular mipmaps.
   * @param {Boolean} [options.backFaceCulling=true] Whether to cull back-facing geometry. When true, back face culling is determined by the glTF material's doubleSided property; when false, back face culling is disabled.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Draws the bounding sphere for the collection.
   * @param {Boolean} [options.debugWireframe=false] For debugging only. Draws the instances in wireframe.
   *
   * @exception {DeveloperError} Must specify either <options.gltf> or <options.url>, but not both.
   * @exception {DeveloperError} Shader program cannot be optimized for instancing. Parameters cannot have any of the following semantics: MODEL, MODELINVERSE, MODELVIEWINVERSE, MODELVIEWPROJECTIONINVERSE, MODELINVERSETRANSPOSE.
   *
   * @private
   */
  function ModelInstanceCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.gltf) && !defined(options.url)) {
      throw new DeveloperError("Either options.gltf or options.url is required.");
    }

    if (defined(options.gltf) && defined(options.url)) {
      throw new DeveloperError(
        "Cannot pass in both options.gltf and options.url."
      );
    }
    //>>includeEnd('debug');

    this.show = defaultValue(options.show, true);

    this._instancingSupported = false;
    this._dynamic = defaultValue(options.dynamic, false);
    this._allowPicking = defaultValue(options.allowPicking, true);
    this._ready = false;
    this._readyPromise = when.defer();
    this._state = LoadState.NEEDS_LOAD;
    this._dirty = false;

    // Undocumented options
    this._cull = defaultValue(options.cull, true);
    this._opaquePass = defaultValue(options.opaquePass, Pass$1.OPAQUE);

    this._instances = createInstances(this, options.instances);

    // When the model instance collection is backed by an i3dm tile,
    // use its batch table resources to modify the shaders, attributes, and uniform maps.
    this._batchTable = options.batchTable;

    this._model = undefined;
    this._vertexBufferTypedArray = undefined; // Hold onto the vertex buffer contents when dynamic is true
    this._vertexBuffer = undefined;
    this._batchIdBuffer = undefined;
    this._instancedUniformsByProgram = undefined;

    this._drawCommands = [];
    this._modelCommands = undefined;

    this._renderStates = undefined;
    this._disableCullingRenderStates = undefined;

    this._boundingSphere = createBoundingSphere(this);
    this._center = Cartesian3.clone(this._boundingSphere.center);
    this._rtcTransform = new Matrix4();
    this._rtcModelView = new Matrix4(); // Holds onto uniform

    this._mode = undefined;

    this.modelMatrix = Matrix4.clone(Matrix4.IDENTITY);
    this._modelMatrix = Matrix4.clone(this.modelMatrix);

    // Passed on to Model
    this._url = Resource.createIfNeeded(options.url);
    this._requestType = options.requestType;
    this._gltf = options.gltf;
    this._basePath = Resource.createIfNeeded(options.basePath);
    this._asynchronous = options.asynchronous;
    this._incrementallyLoadTextures = options.incrementallyLoadTextures;
    this._upAxis = options.upAxis; // Undocumented option
    this._forwardAxis = options.forwardAxis; // Undocumented option

    this.shadows = defaultValue(options.shadows, ShadowMode$1.ENABLED);
    this._shadows = this.shadows;

    this._pickIdLoaded = options.pickIdLoaded;

    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );
    this._debugShowBoundingVolume = false;

    this.debugWireframe = defaultValue(options.debugWireframe, false);
    this._debugWireframe = false;

    this._imageBasedLightingFactor = new Cartesian2(1.0, 1.0);
    Cartesian2.clone(
      options.imageBasedLightingFactor,
      this._imageBasedLightingFactor
    );
    this.lightColor = options.lightColor;
    this.luminanceAtZenith = options.luminanceAtZenith;
    this.sphericalHarmonicCoefficients = options.sphericalHarmonicCoefficients;
    this.specularEnvironmentMaps = options.specularEnvironmentMaps;
    this.backFaceCulling = defaultValue(options.backFaceCulling, true);
    this._backFaceCulling = this.backFaceCulling;
  }

  Object.defineProperties(ModelInstanceCollection.prototype, {
    allowPicking: {
      get: function () {
        return this._allowPicking;
      },
    },
    length: {
      get: function () {
        return this._instances.length;
      },
    },
    activeAnimations: {
      get: function () {
        return this._model.activeAnimations;
      },
    },
    ready: {
      get: function () {
        return this._ready;
      },
    },
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
    imageBasedLightingFactor: {
      get: function () {
        return this._imageBasedLightingFactor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.object("imageBasedLightingFactor", value);
        Check.typeOf.number.greaterThanOrEquals(
          "imageBasedLightingFactor.x",
          value.x,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "imageBasedLightingFactor.x",
          value.x,
          1.0
        );
        Check.typeOf.number.greaterThanOrEquals(
          "imageBasedLightingFactor.y",
          value.y,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "imageBasedLightingFactor.y",
          value.y,
          1.0
        );
        //>>includeEnd('debug');
        Cartesian2.clone(value, this._imageBasedLightingFactor);
      },
    },
  });

  function createInstances(collection, instancesOptions) {
    instancesOptions = defaultValue(instancesOptions, []);
    var length = instancesOptions.length;
    var instances = new Array(length);
    for (var i = 0; i < length; ++i) {
      var instanceOptions = instancesOptions[i];
      var modelMatrix = instanceOptions.modelMatrix;
      var instanceId = defaultValue(instanceOptions.batchId, i);
      instances[i] = new ModelInstance(collection, modelMatrix, instanceId);
    }
    return instances;
  }

  function createBoundingSphere(collection) {
    var instancesLength = collection.length;
    var points = new Array(instancesLength);
    for (var i = 0; i < instancesLength; ++i) {
      points[i] = Matrix4.getTranslation(
        collection._instances[i]._modelMatrix,
        new Cartesian3()
      );
    }

    return BoundingSphere.fromPoints(points);
  }

  var scratchCartesian$2 = new Cartesian3();
  var scratchMatrix$1 = new Matrix4();

  ModelInstanceCollection.prototype.expandBoundingSphere = function (
    instanceModelMatrix
  ) {
    var translation = Matrix4.getTranslation(
      instanceModelMatrix,
      scratchCartesian$2
    );
    BoundingSphere.expand(
      this._boundingSphere,
      translation,
      this._boundingSphere
    );
  };

  function getCheckUniformSemanticFunction(
    modelSemantics,
    supportedSemantics,
    programId,
    uniformMap
  ) {
    return function (uniform, uniformName) {
      var semantic = uniform.semantic;
      if (defined(semantic) && modelSemantics.indexOf(semantic) > -1) {
        if (supportedSemantics.indexOf(semantic) > -1) {
          uniformMap[uniformName] = semantic;
        } else {
          throw new RuntimeError(
            "Shader program cannot be optimized for instancing. " +
              'Uniform "' +
              uniformName +
              '" in program "' +
              programId +
              '" uses unsupported semantic "' +
              semantic +
              '"'
          );
        }
      }
    };
  }

  function getInstancedUniforms(collection, programId) {
    if (defined(collection._instancedUniformsByProgram)) {
      return collection._instancedUniformsByProgram[programId];
    }

    var instancedUniformsByProgram = {};
    collection._instancedUniformsByProgram = instancedUniformsByProgram;

    // When using CESIUM_RTC_MODELVIEW the CESIUM_RTC center is ignored. Instances are always rendered relative-to-center.
    var modelSemantics = [
      "MODEL",
      "MODELVIEW",
      "CESIUM_RTC_MODELVIEW",
      "MODELVIEWPROJECTION",
      "MODELINVERSE",
      "MODELVIEWINVERSE",
      "MODELVIEWPROJECTIONINVERSE",
      "MODELINVERSETRANSPOSE",
      "MODELVIEWINVERSETRANSPOSE",
    ];
    var supportedSemantics = [
      "MODELVIEW",
      "CESIUM_RTC_MODELVIEW",
      "MODELVIEWPROJECTION",
      "MODELVIEWINVERSETRANSPOSE",
    ];

    var techniques = collection._model._sourceTechniques;
    for (var techniqueId in techniques) {
      if (techniques.hasOwnProperty(techniqueId)) {
        var technique = techniques[techniqueId];
        var program = technique.program;

        // Different techniques may share the same program, skip if already processed.
        // This assumes techniques that share a program do not declare different semantics for the same uniforms.
        if (!defined(instancedUniformsByProgram[program])) {
          var uniformMap = {};
          instancedUniformsByProgram[program] = uniformMap;
          ForEach.techniqueUniform(
            technique,
            getCheckUniformSemanticFunction(
              modelSemantics,
              supportedSemantics,
              programId,
              uniformMap
            )
          );
        }
      }
    }

    return instancedUniformsByProgram[programId];
  }

  function getVertexShaderCallback$1(collection) {
    return function (vs, programId) {
      var instancedUniforms = getInstancedUniforms(collection, programId);
      var usesBatchTable = defined(collection._batchTable);

      var renamedSource = ShaderSource.replaceMain(vs, "czm_instancing_main");

      var globalVarsHeader = "";
      var globalVarsMain = "";
      for (var uniform in instancedUniforms) {
        if (instancedUniforms.hasOwnProperty(uniform)) {
          var semantic = instancedUniforms[uniform];
          var varName;
          if (semantic === "MODELVIEW" || semantic === "CESIUM_RTC_MODELVIEW") {
            varName = "czm_instanced_modelView";
          } else if (semantic === "MODELVIEWPROJECTION") {
            varName = "czm_instanced_modelViewProjection";
            globalVarsHeader += "mat4 czm_instanced_modelViewProjection;\n";
            globalVarsMain +=
              "czm_instanced_modelViewProjection = czm_projection * czm_instanced_modelView;\n";
          } else if (semantic === "MODELVIEWINVERSETRANSPOSE") {
            varName = "czm_instanced_modelViewInverseTranspose";
            globalVarsHeader += "mat3 czm_instanced_modelViewInverseTranspose;\n";
            globalVarsMain +=
              "czm_instanced_modelViewInverseTranspose = mat3(czm_instanced_modelView);\n";
          }

          // Remove the uniform declaration
          var regex = new RegExp("uniform.*" + uniform + ".*");
          renamedSource = renamedSource.replace(regex, "");

          // Replace all occurrences of the uniform with the global variable
          regex = new RegExp(uniform + "\\b", "g");
          renamedSource = renamedSource.replace(regex, varName);
        }
      }

      // czm_instanced_model is the model matrix of the instance relative to center
      // czm_instanced_modifiedModelView is the transform from the center to view
      // czm_instanced_nodeTransform is the local offset of the node within the model
      var uniforms =
        "uniform mat4 czm_instanced_modifiedModelView;\n" +
        "uniform mat4 czm_instanced_nodeTransform;\n";

      var batchIdAttribute;
      var pickAttribute;
      var pickVarying;

      if (usesBatchTable) {
        batchIdAttribute = "attribute float a_batchId;\n";
        pickAttribute = "";
        pickVarying = "";
      } else {
        batchIdAttribute = "";
        pickAttribute =
          "attribute vec4 pickColor;\n" + "varying vec4 v_pickColor;\n";
        pickVarying = "    v_pickColor = pickColor;\n";
      }

      var instancedSource =
        uniforms +
        globalVarsHeader +
        "mat4 czm_instanced_modelView;\n" +
        "attribute vec4 czm_modelMatrixRow0;\n" +
        "attribute vec4 czm_modelMatrixRow1;\n" +
        "attribute vec4 czm_modelMatrixRow2;\n" +
        batchIdAttribute +
        pickAttribute +
        renamedSource +
        "void main()\n" +
        "{\n" +
        "    mat4 czm_instanced_model = mat4(czm_modelMatrixRow0.x, czm_modelMatrixRow1.x, czm_modelMatrixRow2.x, 0.0, czm_modelMatrixRow0.y, czm_modelMatrixRow1.y, czm_modelMatrixRow2.y, 0.0, czm_modelMatrixRow0.z, czm_modelMatrixRow1.z, czm_modelMatrixRow2.z, 0.0, czm_modelMatrixRow0.w, czm_modelMatrixRow1.w, czm_modelMatrixRow2.w, 1.0);\n" +
        "    czm_instanced_modelView = czm_instanced_modifiedModelView * czm_instanced_model * czm_instanced_nodeTransform;\n" +
        globalVarsMain +
        "    czm_instancing_main();\n" +
        pickVarying +
        "}\n";

      if (usesBatchTable) {
        var gltf = collection._model.gltf;
        var diffuseAttributeOrUniformName = ModelUtility.getDiffuseAttributeOrUniform(
          gltf,
          programId
        );
        instancedSource = collection._batchTable.getVertexShaderCallback(
          true,
          "a_batchId",
          diffuseAttributeOrUniformName
        )(instancedSource);
      }

      return instancedSource;
    };
  }

  function getFragmentShaderCallback$1(collection) {
    return function (fs, programId) {
      var batchTable = collection._batchTable;
      if (defined(batchTable)) {
        var gltf = collection._model.gltf;
        var diffuseAttributeOrUniformName = ModelUtility.getDiffuseAttributeOrUniform(
          gltf,
          programId
        );
        fs = batchTable.getFragmentShaderCallback(
          true,
          diffuseAttributeOrUniformName
        )(fs);
      } else {
        fs = "varying vec4 v_pickColor;\n" + fs;
      }
      return fs;
    };
  }

  function createModifiedModelView(collection, context) {
    return function () {
      return Matrix4.multiply(
        context.uniformState.view,
        collection._rtcTransform,
        collection._rtcModelView
      );
    };
  }

  function createNodeTransformFunction(node) {
    return function () {
      return node.computedMatrix;
    };
  }

  function getUniformMapCallback(collection, context) {
    return function (uniformMap, programId, node) {
      uniformMap = clone(uniformMap);
      uniformMap.czm_instanced_modifiedModelView = createModifiedModelView(
        collection,
        context
      );
      uniformMap.czm_instanced_nodeTransform = createNodeTransformFunction(node);

      // Remove instanced uniforms from the uniform map
      var instancedUniforms = getInstancedUniforms(collection, programId);
      for (var uniform in instancedUniforms) {
        if (instancedUniforms.hasOwnProperty(uniform)) {
          delete uniformMap[uniform];
        }
      }

      if (defined(collection._batchTable)) {
        uniformMap = collection._batchTable.getUniformMapCallback()(uniformMap);
      }

      return uniformMap;
    };
  }

  function getVertexShaderNonInstancedCallback(collection) {
    return function (vs, programId) {
      if (defined(collection._batchTable)) {
        var gltf = collection._model.gltf;
        var diffuseAttributeOrUniformName = ModelUtility.getDiffuseAttributeOrUniform(
          gltf,
          programId
        );
        vs = collection._batchTable.getVertexShaderCallback(
          true,
          "a_batchId",
          diffuseAttributeOrUniformName
        )(vs);
        // Treat a_batchId as a uniform rather than a vertex attribute
        vs = "uniform float a_batchId\n;" + vs;
      }
      return vs;
    };
  }

  function getFragmentShaderNonInstancedCallback(collection) {
    return function (fs, programId) {
      var batchTable = collection._batchTable;
      if (defined(batchTable)) {
        var gltf = collection._model.gltf;
        var diffuseAttributeOrUniformName = ModelUtility.getDiffuseAttributeOrUniform(
          gltf,
          programId
        );
        fs = batchTable.getFragmentShaderCallback(
          true,
          diffuseAttributeOrUniformName
        )(fs);
      } else {
        fs = "uniform vec4 czm_pickColor;\n" + fs;
      }
      return fs;
    };
  }

  function getUniformMapNonInstancedCallback(collection) {
    return function (uniformMap) {
      if (defined(collection._batchTable)) {
        uniformMap = collection._batchTable.getUniformMapCallback()(uniformMap);
      }

      return uniformMap;
    };
  }

  function getVertexBufferTypedArray(collection) {
    var instances = collection._instances;
    var instancesLength = collection.length;
    var collectionCenter = collection._center;
    var vertexSizeInFloats = 12;

    var bufferData = collection._vertexBufferTypedArray;
    if (!defined(bufferData)) {
      bufferData = new Float32Array(instancesLength * vertexSizeInFloats);
    }
    if (collection._dynamic) {
      // Hold onto the buffer data so we don't have to allocate new memory every frame.
      collection._vertexBufferTypedArray = bufferData;
    }

    for (var i = 0; i < instancesLength; ++i) {
      var modelMatrix = instances[i]._modelMatrix;

      // Instance matrix is relative to center
      var instanceMatrix = Matrix4.clone(modelMatrix, scratchMatrix$1);
      instanceMatrix[12] -= collectionCenter.x;
      instanceMatrix[13] -= collectionCenter.y;
      instanceMatrix[14] -= collectionCenter.z;

      var offset = i * vertexSizeInFloats;

      // First three rows of the model matrix
      bufferData[offset + 0] = instanceMatrix[0];
      bufferData[offset + 1] = instanceMatrix[4];
      bufferData[offset + 2] = instanceMatrix[8];
      bufferData[offset + 3] = instanceMatrix[12];
      bufferData[offset + 4] = instanceMatrix[1];
      bufferData[offset + 5] = instanceMatrix[5];
      bufferData[offset + 6] = instanceMatrix[9];
      bufferData[offset + 7] = instanceMatrix[13];
      bufferData[offset + 8] = instanceMatrix[2];
      bufferData[offset + 9] = instanceMatrix[6];
      bufferData[offset + 10] = instanceMatrix[10];
      bufferData[offset + 11] = instanceMatrix[14];
    }

    return bufferData;
  }

  function createVertexBuffer$2(collection, context) {
    var i;
    var instances = collection._instances;
    var instancesLength = collection.length;
    var dynamic = collection._dynamic;
    var usesBatchTable = defined(collection._batchTable);

    if (usesBatchTable) {
      var batchIdBufferData = new Uint16Array(instancesLength);
      for (i = 0; i < instancesLength; ++i) {
        batchIdBufferData[i] = instances[i]._instanceId;
      }
      collection._batchIdBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: batchIdBufferData,
        usage: BufferUsage$1.STATIC_DRAW,
      });
    }

    if (!usesBatchTable) {
      var pickIdBuffer = new Uint8Array(instancesLength * 4);
      for (i = 0; i < instancesLength; ++i) {
        var pickId = collection._pickIds[i];
        var pickColor = pickId.color;
        var offset = i * 4;
        pickIdBuffer[offset] = Color.floatToByte(pickColor.red);
        pickIdBuffer[offset + 1] = Color.floatToByte(pickColor.green);
        pickIdBuffer[offset + 2] = Color.floatToByte(pickColor.blue);
        pickIdBuffer[offset + 3] = Color.floatToByte(pickColor.alpha);
      }
      collection._pickIdBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: pickIdBuffer,
        usage: BufferUsage$1.STATIC_DRAW,
      });
    }

    var vertexBufferTypedArray = getVertexBufferTypedArray(collection);
    collection._vertexBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: vertexBufferTypedArray,
      usage: dynamic ? BufferUsage$1.STREAM_DRAW : BufferUsage$1.STATIC_DRAW,
    });
  }

  function updateVertexBuffer(collection) {
    var vertexBufferTypedArray = getVertexBufferTypedArray(collection);
    collection._vertexBuffer.copyFromArrayView(vertexBufferTypedArray);
  }

  function createPickIds(collection, context) {
    // PERFORMANCE_IDEA: we could skip the pick buffer completely by allocating
    // a continuous range of pickIds and then converting the base pickId + batchId
    // to RGBA in the shader.  The only consider is precision issues, which might
    // not be an issue in WebGL 2.
    var instances = collection._instances;
    var instancesLength = instances.length;
    var pickIds = new Array(instancesLength);
    for (var i = 0; i < instancesLength; ++i) {
      pickIds[i] = context.createPickId(instances[i]);
    }
    return pickIds;
  }

  function createModel(collection, context) {
    var instancingSupported = collection._instancingSupported;
    var usesBatchTable = defined(collection._batchTable);
    var allowPicking = collection._allowPicking;

    var modelOptions = {
      url: collection._url,
      requestType: collection._requestType,
      gltf: collection._gltf,
      basePath: collection._basePath,
      shadows: collection._shadows,
      cacheKey: undefined,
      asynchronous: collection._asynchronous,
      allowPicking: allowPicking,
      incrementallyLoadTextures: collection._incrementallyLoadTextures,
      upAxis: collection._upAxis,
      forwardAxis: collection._forwardAxis,
      precreatedAttributes: undefined,
      vertexShaderLoaded: undefined,
      fragmentShaderLoaded: undefined,
      uniformMapLoaded: undefined,
      pickIdLoaded: collection._pickIdLoaded,
      ignoreCommands: true,
      opaquePass: collection._opaquePass,
      imageBasedLightingFactor: collection.imageBasedLightingFactor,
      lightColor: collection.lightColor,
      luminanceAtZenith: collection.luminanceAtZenith,
      sphericalHarmonicCoefficients: collection.sphericalHarmonicCoefficients,
      specularEnvironmentMaps: collection.specularEnvironmentMaps,
    };

    if (!usesBatchTable) {
      collection._pickIds = createPickIds(collection, context);
    }

    if (instancingSupported) {
      createVertexBuffer$2(collection, context);

      var vertexSizeInFloats = 12;
      var componentSizeInBytes = ComponentDatatype$1.getSizeInBytes(
        ComponentDatatype$1.FLOAT
      );

      var instancedAttributes = {
        czm_modelMatrixRow0: {
          index: 0, // updated in Model
          vertexBuffer: collection._vertexBuffer,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          normalize: false,
          offsetInBytes: 0,
          strideInBytes: componentSizeInBytes * vertexSizeInFloats,
          instanceDivisor: 1,
        },
        czm_modelMatrixRow1: {
          index: 0, // updated in Model
          vertexBuffer: collection._vertexBuffer,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          normalize: false,
          offsetInBytes: componentSizeInBytes * 4,
          strideInBytes: componentSizeInBytes * vertexSizeInFloats,
          instanceDivisor: 1,
        },
        czm_modelMatrixRow2: {
          index: 0, // updated in Model
          vertexBuffer: collection._vertexBuffer,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          normalize: false,
          offsetInBytes: componentSizeInBytes * 8,
          strideInBytes: componentSizeInBytes * vertexSizeInFloats,
          instanceDivisor: 1,
        },
      };

      // When using a batch table, add a batch id attribute
      if (usesBatchTable) {
        instancedAttributes.a_batchId = {
          index: 0, // updated in Model
          vertexBuffer: collection._batchIdBuffer,
          componentsPerAttribute: 1,
          componentDatatype: ComponentDatatype$1.UNSIGNED_SHORT,
          normalize: false,
          offsetInBytes: 0,
          strideInBytes: 0,
          instanceDivisor: 1,
        };
      }

      if (!usesBatchTable) {
        instancedAttributes.pickColor = {
          index: 0, // updated in Model
          vertexBuffer: collection._pickIdBuffer,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          normalize: true,
          offsetInBytes: 0,
          strideInBytes: 0,
          instanceDivisor: 1,
        };
      }

      modelOptions.precreatedAttributes = instancedAttributes;
      modelOptions.vertexShaderLoaded = getVertexShaderCallback$1(collection);
      modelOptions.fragmentShaderLoaded = getFragmentShaderCallback$1(collection);
      modelOptions.uniformMapLoaded = getUniformMapCallback(collection, context);

      if (defined(collection._url)) {
        modelOptions.cacheKey = collection._url.getUrlComponent() + "#instanced";
      }
    } else {
      modelOptions.vertexShaderLoaded = getVertexShaderNonInstancedCallback(
        collection
      );
      modelOptions.fragmentShaderLoaded = getFragmentShaderNonInstancedCallback(
        collection
      );
      modelOptions.uniformMapLoaded = getUniformMapNonInstancedCallback(
        collection);
    }

    if (defined(collection._url)) {
      collection._model = Model.fromGltf(modelOptions);
    } else {
      collection._model = new Model(modelOptions);
    }
  }

  function updateWireframe$2(collection, force) {
    if (collection._debugWireframe !== collection.debugWireframe || force) {
      collection._debugWireframe = collection.debugWireframe;

      // This assumes the original primitive was TRIANGLES and that the triangles
      // are connected for the wireframe to look perfect.
      var primitiveType = collection.debugWireframe
        ? PrimitiveType$1.LINES
        : PrimitiveType$1.TRIANGLES;
      var commands = collection._drawCommands;
      var length = commands.length;
      for (var i = 0; i < length; ++i) {
        commands[i].primitiveType = primitiveType;
      }
    }
  }

  function getDisableCullingRenderState$1(renderState) {
    var rs = clone(renderState, true);
    rs.cull.enabled = false;
    return RenderState.fromCache(rs);
  }

  function updateBackFaceCulling$1(collection, force) {
    if (collection._backFaceCulling !== collection.backFaceCulling || force) {
      collection._backFaceCulling = collection.backFaceCulling;

      var commands = collection._drawCommands;
      var length = commands.length;
      var i;

      if (!defined(collection._disableCullingRenderStates)) {
        collection._disableCullingRenderStates = new Array(length);
        collection._renderStates = new Array(length);
        for (i = 0; i < length; ++i) {
          var renderState = commands[i].renderState;
          var derivedRenderState = getDisableCullingRenderState$1(renderState);
          collection._disableCullingRenderStates[i] = derivedRenderState;
          collection._renderStates[i] = renderState;
        }
      }

      for (i = 0; i < length; ++i) {
        commands[i].renderState = collection._backFaceCulling
          ? collection._renderStates[i]
          : collection._disableCullingRenderStates[i];
      }
    }
  }

  function updateShowBoundingVolume$1(collection, force) {
    if (
      collection.debugShowBoundingVolume !==
        collection._debugShowBoundingVolume ||
      force
    ) {
      collection._debugShowBoundingVolume = collection.debugShowBoundingVolume;

      var commands = collection._drawCommands;
      var length = commands.length;
      for (var i = 0; i < length; ++i) {
        commands[i].debugShowBoundingVolume = collection.debugShowBoundingVolume;
      }
    }
  }

  function createCommands$3(collection, drawCommands) {
    var commandsLength = drawCommands.length;
    var instancesLength = collection.length;
    var boundingSphere = collection._boundingSphere;
    var cull = collection._cull;

    for (var i = 0; i < commandsLength; ++i) {
      var drawCommand = DrawCommand.shallowClone(drawCommands[i]);
      drawCommand.instanceCount = instancesLength;
      drawCommand.boundingVolume = boundingSphere;
      drawCommand.cull = cull;
      if (defined(collection._batchTable)) {
        drawCommand.pickId = collection._batchTable.getPickId();
      } else {
        drawCommand.pickId = "v_pickColor";
      }
      collection._drawCommands.push(drawCommand);
    }
  }

  function createBatchIdFunction(batchId) {
    return function () {
      return batchId;
    };
  }

  function createPickColorFunction$1(color) {
    return function () {
      return color;
    };
  }

  function createCommandsNonInstanced(collection, drawCommands) {
    // When instancing is disabled, create commands for every instance.
    var instances = collection._instances;
    var commandsLength = drawCommands.length;
    var instancesLength = collection.length;
    var batchTable = collection._batchTable;
    var usesBatchTable = defined(batchTable);
    var cull = collection._cull;

    for (var i = 0; i < commandsLength; ++i) {
      for (var j = 0; j < instancesLength; ++j) {
        var drawCommand = DrawCommand.shallowClone(drawCommands[i]);
        drawCommand.modelMatrix = new Matrix4(); // Updated in updateCommandsNonInstanced
        drawCommand.boundingVolume = new BoundingSphere(); // Updated in updateCommandsNonInstanced
        drawCommand.cull = cull;
        drawCommand.uniformMap = clone(drawCommand.uniformMap);
        if (usesBatchTable) {
          drawCommand.uniformMap.a_batchId = createBatchIdFunction(
            instances[j]._instanceId
          );
        } else {
          var pickId = collection._pickIds[j];
          drawCommand.uniformMap.czm_pickColor = createPickColorFunction$1(
            pickId.color
          );
        }
        collection._drawCommands.push(drawCommand);
      }
    }
  }

  function updateCommandsNonInstanced(collection) {
    var modelCommands = collection._modelCommands;
    var commandsLength = modelCommands.length;
    var instancesLength = collection.length;
    var collectionTransform = collection._rtcTransform;
    var collectionCenter = collection._center;

    for (var i = 0; i < commandsLength; ++i) {
      var modelCommand = modelCommands[i];
      for (var j = 0; j < instancesLength; ++j) {
        var commandIndex = i * instancesLength + j;
        var drawCommand = collection._drawCommands[commandIndex];
        var instanceMatrix = Matrix4.clone(
          collection._instances[j]._modelMatrix,
          scratchMatrix$1
        );
        instanceMatrix[12] -= collectionCenter.x;
        instanceMatrix[13] -= collectionCenter.y;
        instanceMatrix[14] -= collectionCenter.z;
        instanceMatrix = Matrix4.multiply(
          collectionTransform,
          instanceMatrix,
          scratchMatrix$1
        );
        var nodeMatrix = modelCommand.modelMatrix;
        var modelMatrix = drawCommand.modelMatrix;
        Matrix4.multiply(instanceMatrix, nodeMatrix, modelMatrix);

        var nodeBoundingSphere = modelCommand.boundingVolume;
        var boundingSphere = drawCommand.boundingVolume;
        BoundingSphere.transform(
          nodeBoundingSphere,
          instanceMatrix,
          boundingSphere
        );
      }
    }
  }

  function getModelCommands(model) {
    var nodeCommands = model._nodeCommands;
    var length = nodeCommands.length;

    var drawCommands = [];

    for (var i = 0; i < length; ++i) {
      var nc = nodeCommands[i];
      if (nc.show) {
        drawCommands.push(nc.command);
      }
    }

    return drawCommands;
  }

  function commandsDirty(model) {
    var nodeCommands = model._nodeCommands;
    var length = nodeCommands.length;

    var commandsDirty = false;

    for (var i = 0; i < length; i++) {
      var nc = nodeCommands[i];
      if (nc.command.dirty) {
        nc.command.dirty = false;
        commandsDirty = true;
      }
    }
    return commandsDirty;
  }

  function generateModelCommands(modelInstanceCollection, instancingSupported) {
    modelInstanceCollection._drawCommands = [];

    var modelCommands = getModelCommands(modelInstanceCollection._model);
    if (instancingSupported) {
      createCommands$3(modelInstanceCollection, modelCommands);
    } else {
      createCommandsNonInstanced(modelInstanceCollection, modelCommands);
      updateCommandsNonInstanced(modelInstanceCollection);
    }
  }

  function updateShadows$1(collection, force) {
    if (collection.shadows !== collection._shadows || force) {
      collection._shadows = collection.shadows;

      var castShadows = ShadowMode$1.castShadows(collection.shadows);
      var receiveShadows = ShadowMode$1.receiveShadows(collection.shadows);

      var drawCommands = collection._drawCommands;
      var length = drawCommands.length;
      for (var i = 0; i < length; ++i) {
        var drawCommand = drawCommands[i];
        drawCommand.castShadows = castShadows;
        drawCommand.receiveShadows = receiveShadows;
      }
    }
  }

  ModelInstanceCollection.prototype.update = function (frameState) {
    if (frameState.mode === SceneMode$1.MORPHING) {
      return;
    }

    if (!this.show) {
      return;
    }

    if (this.length === 0) {
      return;
    }

    var context = frameState.context;

    if (this._state === LoadState.NEEDS_LOAD) {
      this._state = LoadState.LOADING;
      this._instancingSupported = context.instancedArrays;
      createModel(this, context);
      var that = this;
      this._model.readyPromise.otherwise(function (error) {
        that._state = LoadState.FAILED;
        that._readyPromise.reject(error);
      });
    }

    var instancingSupported = this._instancingSupported;
    var model = this._model;

    model.imageBasedLightingFactor = this.imageBasedLightingFactor;
    model.lightColor = this.lightColor;
    model.luminanceAtZenith = this.luminanceAtZenith;
    model.sphericalHarmonicCoefficients = this.sphericalHarmonicCoefficients;
    model.specularEnvironmentMaps = this.specularEnvironmentMaps;

    model.update(frameState);

    if (model.ready && this._state === LoadState.LOADING) {
      this._state = LoadState.LOADED;
      this._ready = true;

      // Expand bounding volume to fit the radius of the loaded model including the model's offset from the center
      var modelRadius =
        model.boundingSphere.radius +
        Cartesian3.magnitude(model.boundingSphere.center);
      this._boundingSphere.radius += modelRadius;
      this._modelCommands = getModelCommands(model);

      generateModelCommands(this, instancingSupported);

      this._readyPromise.resolve(this);
      return;
    }

    if (this._state !== LoadState.LOADED) {
      return;
    }

    var modeChanged = frameState.mode !== this._mode;
    var modelMatrix = this.modelMatrix;
    var modelMatrixChanged = !Matrix4.equals(this._modelMatrix, modelMatrix);

    if (modeChanged || modelMatrixChanged) {
      this._mode = frameState.mode;
      Matrix4.clone(modelMatrix, this._modelMatrix);
      var rtcTransform = Matrix4.multiplyByTranslation(
        this._modelMatrix,
        this._center,
        this._rtcTransform
      );
      if (this._mode !== SceneMode$1.SCENE3D) {
        rtcTransform = Transforms.basisTo2D(
          frameState.mapProjection,
          rtcTransform,
          rtcTransform
        );
      }
      Matrix4.getTranslation(rtcTransform, this._boundingSphere.center);
    }

    if (instancingSupported && this._dirty) {
      // If at least one instance has moved assume the collection is now dynamic
      this._dynamic = true;
      this._dirty = false;

      // PERFORMANCE_IDEA: only update dirty sub-sections instead of the whole collection
      updateVertexBuffer(this);
    }

    // If the model was set to rebuild shaders during update, rebuild instanced commands.
    var modelCommandsDirty = commandsDirty(model);
    if (modelCommandsDirty) {
      generateModelCommands(this, instancingSupported);
    }

    // If any node changes due to an animation, update the commands. This could be inefficient if the model is
    // composed of many nodes and only one changes, however it is probably fine in the general use case.
    // Only applies when instancing is disabled. The instanced shader automatically handles node transformations.
    if (
      !instancingSupported &&
      (model.dirty || this._dirty || modeChanged || modelMatrixChanged)
    ) {
      updateCommandsNonInstanced(this);
    }

    updateShadows$1(this, modelCommandsDirty);
    updateWireframe$2(this, modelCommandsDirty);
    updateBackFaceCulling$1(this, modelCommandsDirty);
    updateShowBoundingVolume$1(this, modelCommandsDirty);

    var passes = frameState.passes;
    if (!passes.render && !passes.pick) {
      return;
    }

    var commandList = frameState.commandList;
    var commands = this._drawCommands;
    var commandsLength = commands.length;

    for (var i = 0; i < commandsLength; ++i) {
      commandList.push(commands[i]);
    }
  };

  ModelInstanceCollection.prototype.isDestroyed = function () {
    return false;
  };

  ModelInstanceCollection.prototype.destroy = function () {
    this._model = this._model && this._model.destroy();

    var pickIds = this._pickIds;
    if (defined(pickIds)) {
      var length = pickIds.length;
      for (var i = 0; i < length; ++i) {
        pickIds[i].destroy();
      }
    }

    return destroyObject(this);
  };

  /**
   * Represents the contents of a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Instanced3DModel|Instanced 3D Model}
   * tile in a {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Instanced3DModel3DTileContent
   * @constructor
   *
   * @private
   */
  function Instanced3DModel3DTileContent(
    tileset,
    tile,
    resource,
    arrayBuffer,
    byteOffset
  ) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;
    this._modelInstanceCollection = undefined;
    this._batchTable = undefined;
    this._features = undefined;

    this.featurePropertiesDirty = false;

    initialize$5(this, arrayBuffer, byteOffset);
  }

  // This can be overridden for testing purposes
  Instanced3DModel3DTileContent._deprecationWarning = deprecationWarning;

  Object.defineProperties(Instanced3DModel3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        return this._batchTable.featuresLength;
      },
    },

    pointsLength: {
      get: function () {
        return 0;
      },
    },

    trianglesLength: {
      get: function () {
        var model = this._modelInstanceCollection._model;
        if (defined(model)) {
          return model.trianglesLength;
        }
        return 0;
      },
    },

    geometryByteLength: {
      get: function () {
        var model = this._modelInstanceCollection._model;
        if (defined(model)) {
          return model.geometryByteLength;
        }
        return 0;
      },
    },

    texturesByteLength: {
      get: function () {
        var model = this._modelInstanceCollection._model;
        if (defined(model)) {
          return model.texturesByteLength;
        }
        return 0;
      },
    },

    batchTableByteLength: {
      get: function () {
        return this._batchTable.memorySizeInBytes;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return this._modelInstanceCollection.readyPromise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    batchTable: {
      get: function () {
        return this._batchTable;
      },
    },
  });

  function getPickIdCallback$1(content) {
    return function () {
      return content._batchTable.getPickId();
    };
  }

  var sizeOfUint32$6 = Uint32Array.BYTES_PER_ELEMENT;
  var propertyScratch1 = new Array(4);
  var propertyScratch2 = new Array(4);

  function initialize$5(content, arrayBuffer, byteOffset) {
    var byteStart = defaultValue(byteOffset, 0);
    byteOffset = byteStart;

    var uint8Array = new Uint8Array(arrayBuffer);
    var view = new DataView(arrayBuffer);
    byteOffset += sizeOfUint32$6; // Skip magic

    var version = view.getUint32(byteOffset, true);
    if (version !== 1) {
      throw new RuntimeError(
        "Only Instanced 3D Model version 1 is supported. Version " +
          version +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$6;

    var byteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$6;

    var featureTableJsonByteLength = view.getUint32(byteOffset, true);
    if (featureTableJsonByteLength === 0) {
      throw new RuntimeError(
        "featureTableJsonByteLength is zero, the feature table must be defined."
      );
    }
    byteOffset += sizeOfUint32$6;

    var featureTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$6;

    var batchTableJsonByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$6;

    var batchTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$6;

    var gltfFormat = view.getUint32(byteOffset, true);
    if (gltfFormat !== 1 && gltfFormat !== 0) {
      throw new RuntimeError(
        "Only glTF format 0 (uri) or 1 (embedded) are supported. Format " +
          gltfFormat +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$6;

    var featureTableString = getStringFromTypedArray(
      uint8Array,
      byteOffset,
      featureTableJsonByteLength
    );
    var featureTableJson = JSON.parse(featureTableString);
    byteOffset += featureTableJsonByteLength;

    var featureTableBinary = new Uint8Array(
      arrayBuffer,
      byteOffset,
      featureTableBinaryByteLength
    );
    byteOffset += featureTableBinaryByteLength;

    var featureTable = new Cesium3DTileFeatureTable(
      featureTableJson,
      featureTableBinary
    );
    var instancesLength = featureTable.getGlobalProperty("INSTANCES_LENGTH");
    featureTable.featuresLength = instancesLength;

    if (!defined(instancesLength)) {
      throw new RuntimeError(
        "Feature table global property: INSTANCES_LENGTH must be defined"
      );
    }

    var batchTableJson;
    var batchTableBinary;
    if (batchTableJsonByteLength > 0) {
      var batchTableString = getStringFromTypedArray(
        uint8Array,
        byteOffset,
        batchTableJsonByteLength
      );
      batchTableJson = JSON.parse(batchTableString);
      byteOffset += batchTableJsonByteLength;

      if (batchTableBinaryByteLength > 0) {
        // Has a batch table binary
        batchTableBinary = new Uint8Array(
          arrayBuffer,
          byteOffset,
          batchTableBinaryByteLength
        );
        // Copy the batchTableBinary section and let the underlying ArrayBuffer be freed
        batchTableBinary = new Uint8Array(batchTableBinary);
        byteOffset += batchTableBinaryByteLength;
      }
    }

    content._batchTable = new Cesium3DTileBatchTable(
      content,
      instancesLength,
      batchTableJson,
      batchTableBinary
    );

    var gltfByteLength = byteStart + byteLength - byteOffset;
    if (gltfByteLength === 0) {
      throw new RuntimeError(
        "glTF byte length is zero, i3dm must have a glTF to instance."
      );
    }

    var gltfView;
    if (byteOffset % 4 === 0) {
      gltfView = new Uint8Array(arrayBuffer, byteOffset, gltfByteLength);
    } else {
      // Create a copy of the glb so that it is 4-byte aligned
      Instanced3DModel3DTileContent._deprecationWarning(
        "i3dm-glb-unaligned",
        "The embedded glb is not aligned to a 4-byte boundary."
      );
      gltfView = new Uint8Array(
        uint8Array.subarray(byteOffset, byteOffset + gltfByteLength)
      );
    }

    var tileset = content._tileset;

    // Create model instance collection
    var collectionOptions = {
      instances: new Array(instancesLength),
      batchTable: content._batchTable,
      cull: false, // Already culled by 3D Tiles
      url: undefined,
      requestType: RequestType$1.TILES3D,
      gltf: undefined,
      basePath: undefined,
      incrementallyLoadTextures: false,
      upAxis: tileset._gltfUpAxis,
      forwardAxis: Axis$1.X,
      opaquePass: Pass$1.CESIUM_3D_TILE, // Draw opaque portions during the 3D Tiles pass
      pickIdLoaded: getPickIdCallback$1(content),
      imageBasedLightingFactor: tileset.imageBasedLightingFactor,
      lightColor: tileset.lightColor,
      luminanceAtZenith: tileset.luminanceAtZenith,
      sphericalHarmonicCoefficients: tileset.sphericalHarmonicCoefficients,
      specularEnvironmentMaps: tileset.specularEnvironmentMaps,
      backFaceCulling: tileset.backFaceCulling,
    };

    if (gltfFormat === 0) {
      var gltfUrl = getStringFromTypedArray(gltfView);

      // We need to remove padding from the end of the model URL in case this tile was part of a composite tile.
      // This removes all white space and null characters from the end of the string.
      gltfUrl = gltfUrl.replace(/[\s\0]+$/, "");
      collectionOptions.url = content._resource.getDerivedResource({
        url: gltfUrl,
      });
    } else {
      collectionOptions.gltf = gltfView;
      collectionOptions.basePath = content._resource.clone();
    }

    var eastNorthUp = featureTable.getGlobalProperty("EAST_NORTH_UP");

    var rtcCenter;
    var rtcCenterArray = featureTable.getGlobalProperty(
      "RTC_CENTER",
      ComponentDatatype$1.FLOAT,
      3
    );
    if (defined(rtcCenterArray)) {
      rtcCenter = Cartesian3.unpack(rtcCenterArray);
    }

    var instances = collectionOptions.instances;
    var instancePosition = new Cartesian3();
    var instancePositionArray = new Array(3);
    var instanceNormalRight = new Cartesian3();
    var instanceNormalUp = new Cartesian3();
    var instanceNormalForward = new Cartesian3();
    var instanceRotation = new Matrix3();
    var instanceQuaternion = new Quaternion();
    var instanceScale = new Cartesian3();
    var instanceTranslationRotationScale = new TranslationRotationScale();
    var instanceTransform = new Matrix4();
    for (var i = 0; i < instancesLength; i++) {
      // Get the instance position
      var position = featureTable.getProperty(
        "POSITION",
        ComponentDatatype$1.FLOAT,
        3,
        i,
        propertyScratch1
      );
      if (!defined(position)) {
        position = instancePositionArray;
        var positionQuantized = featureTable.getProperty(
          "POSITION_QUANTIZED",
          ComponentDatatype$1.UNSIGNED_SHORT,
          3,
          i,
          propertyScratch1
        );
        if (!defined(positionQuantized)) {
          throw new RuntimeError(
            "Either POSITION or POSITION_QUANTIZED must be defined for each instance."
          );
        }
        var quantizedVolumeOffset = featureTable.getGlobalProperty(
          "QUANTIZED_VOLUME_OFFSET",
          ComponentDatatype$1.FLOAT,
          3
        );
        if (!defined(quantizedVolumeOffset)) {
          throw new RuntimeError(
            "Global property: QUANTIZED_VOLUME_OFFSET must be defined for quantized positions."
          );
        }
        var quantizedVolumeScale = featureTable.getGlobalProperty(
          "QUANTIZED_VOLUME_SCALE",
          ComponentDatatype$1.FLOAT,
          3
        );
        if (!defined(quantizedVolumeScale)) {
          throw new RuntimeError(
            "Global property: QUANTIZED_VOLUME_SCALE must be defined for quantized positions."
          );
        }
        for (var j = 0; j < 3; j++) {
          position[j] =
            (positionQuantized[j] / 65535.0) * quantizedVolumeScale[j] +
            quantizedVolumeOffset[j];
        }
      }
      Cartesian3.unpack(position, 0, instancePosition);
      if (defined(rtcCenter)) {
        Cartesian3.add(instancePosition, rtcCenter, instancePosition);
      }
      instanceTranslationRotationScale.translation = instancePosition;

      // Get the instance rotation
      var normalUp = featureTable.getProperty(
        "NORMAL_UP",
        ComponentDatatype$1.FLOAT,
        3,
        i,
        propertyScratch1
      );
      var normalRight = featureTable.getProperty(
        "NORMAL_RIGHT",
        ComponentDatatype$1.FLOAT,
        3,
        i,
        propertyScratch2
      );
      var hasCustomOrientation = false;
      if (defined(normalUp)) {
        if (!defined(normalRight)) {
          throw new RuntimeError(
            "To define a custom orientation, both NORMAL_UP and NORMAL_RIGHT must be defined."
          );
        }
        Cartesian3.unpack(normalUp, 0, instanceNormalUp);
        Cartesian3.unpack(normalRight, 0, instanceNormalRight);
        hasCustomOrientation = true;
      } else {
        var octNormalUp = featureTable.getProperty(
          "NORMAL_UP_OCT32P",
          ComponentDatatype$1.UNSIGNED_SHORT,
          2,
          i,
          propertyScratch1
        );
        var octNormalRight = featureTable.getProperty(
          "NORMAL_RIGHT_OCT32P",
          ComponentDatatype$1.UNSIGNED_SHORT,
          2,
          i,
          propertyScratch2
        );
        if (defined(octNormalUp)) {
          if (!defined(octNormalRight)) {
            throw new RuntimeError(
              "To define a custom orientation with oct-encoded vectors, both NORMAL_UP_OCT32P and NORMAL_RIGHT_OCT32P must be defined."
            );
          }
          AttributeCompression.octDecodeInRange(
            octNormalUp[0],
            octNormalUp[1],
            65535,
            instanceNormalUp
          );
          AttributeCompression.octDecodeInRange(
            octNormalRight[0],
            octNormalRight[1],
            65535,
            instanceNormalRight
          );
          hasCustomOrientation = true;
        } else if (eastNorthUp) {
          Transforms.eastNorthUpToFixedFrame(
            instancePosition,
            Ellipsoid.WGS84,
            instanceTransform
          );
          Matrix4.getMatrix3(instanceTransform, instanceRotation);
        } else {
          Matrix3.clone(Matrix3.IDENTITY, instanceRotation);
        }
      }
      if (hasCustomOrientation) {
        Cartesian3.cross(
          instanceNormalRight,
          instanceNormalUp,
          instanceNormalForward
        );
        Cartesian3.normalize(instanceNormalForward, instanceNormalForward);
        Matrix3.setColumn(
          instanceRotation,
          0,
          instanceNormalRight,
          instanceRotation
        );
        Matrix3.setColumn(
          instanceRotation,
          1,
          instanceNormalUp,
          instanceRotation
        );
        Matrix3.setColumn(
          instanceRotation,
          2,
          instanceNormalForward,
          instanceRotation
        );
      }
      Quaternion.fromRotationMatrix(instanceRotation, instanceQuaternion);
      instanceTranslationRotationScale.rotation = instanceQuaternion;

      // Get the instance scale
      instanceScale = Cartesian3.fromElements(1.0, 1.0, 1.0, instanceScale);
      var scale = featureTable.getProperty(
        "SCALE",
        ComponentDatatype$1.FLOAT,
        1,
        i
      );
      if (defined(scale)) {
        Cartesian3.multiplyByScalar(instanceScale, scale, instanceScale);
      }
      var nonUniformScale = featureTable.getProperty(
        "SCALE_NON_UNIFORM",
        ComponentDatatype$1.FLOAT,
        3,
        i,
        propertyScratch1
      );
      if (defined(nonUniformScale)) {
        instanceScale.x *= nonUniformScale[0];
        instanceScale.y *= nonUniformScale[1];
        instanceScale.z *= nonUniformScale[2];
      }
      instanceTranslationRotationScale.scale = instanceScale;

      // Get the batchId
      var batchId = featureTable.getProperty(
        "BATCH_ID",
        ComponentDatatype$1.UNSIGNED_SHORT,
        1,
        i
      );
      if (!defined(batchId)) {
        // If BATCH_ID semantic is undefined, batchId is just the instance number
        batchId = i;
      }

      // Create the model matrix and the instance
      Matrix4.fromTranslationRotationScale(
        instanceTranslationRotationScale,
        instanceTransform
      );
      var modelMatrix = instanceTransform.clone();
      instances[i] = {
        modelMatrix: modelMatrix,
        batchId: batchId,
      };
    }

    content._modelInstanceCollection = new ModelInstanceCollection(
      collectionOptions
    );
    content._modelInstanceCollection.readyPromise.then(function (collection) {
      collection.activeAnimations.addAll({
        loop: ModelAnimationLoop$1.REPEAT,
      });
    });
  }

  function createFeatures$2(content) {
    var featuresLength = content.featuresLength;
    if (!defined(content._features) && featuresLength > 0) {
      var features = new Array(featuresLength);
      for (var i = 0; i < featuresLength; ++i) {
        features[i] = new Cesium3DTileFeature(content, i);
      }
      content._features = features;
    }
  }

  Instanced3DModel3DTileContent.prototype.hasProperty = function (batchId, name) {
    return this._batchTable.hasProperty(batchId, name);
  };

  Instanced3DModel3DTileContent.prototype.getFeature = function (batchId) {
    var featuresLength = this.featuresLength;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(batchId) || batchId < 0 || batchId >= featuresLength) {
      throw new DeveloperError(
        "batchId is required and between zero and featuresLength - 1 (" +
          (featuresLength - 1) +
          ")."
      );
    }
    //>>includeEnd('debug');

    createFeatures$2(this);
    return this._features[batchId];
  };

  Instanced3DModel3DTileContent.prototype.applyDebugSettings = function (
    enabled,
    color
  ) {
    color = enabled ? color : Color.WHITE;
    this._batchTable.setAllColor(color);
  };

  Instanced3DModel3DTileContent.prototype.applyStyle = function (style) {
    this._batchTable.applyStyle(style);
  };

  Instanced3DModel3DTileContent.prototype.update = function (
    tileset,
    frameState
  ) {
    var commandStart = frameState.commandList.length;

    // In the PROCESSING state we may be calling update() to move forward
    // the content's resource loading.  In the READY state, it will
    // actually generate commands.
    this._batchTable.update(tileset, frameState);
    this._modelInstanceCollection.modelMatrix = this._tile.computedTransform;
    this._modelInstanceCollection.shadows = this._tileset.shadows;
    this._modelInstanceCollection.lightColor = this._tileset.lightColor;
    this._modelInstanceCollection.luminanceAtZenith = this._tileset.luminanceAtZenith;
    this._modelInstanceCollection.sphericalHarmonicCoefficients = this._tileset.sphericalHarmonicCoefficients;
    this._modelInstanceCollection.specularEnvironmentMaps = this._tileset.specularEnvironmentMaps;
    this._modelInstanceCollection.backFaceCulling = this._tileset.backFaceCulling;
    this._modelInstanceCollection.debugWireframe = this._tileset.debugWireframe;

    var model = this._modelInstanceCollection._model;

    if (defined(model)) {
      // Update for clipping planes
      var tilesetClippingPlanes = this._tileset.clippingPlanes;
      model.clippingPlanesOriginMatrix = this._tileset.clippingPlanesOriginMatrix;
      if (defined(tilesetClippingPlanes) && this._tile.clippingPlanesDirty) {
        // Dereference the clipping planes from the model if they are irrelevant - saves on shading
        // Link/Dereference directly to avoid ownership checks.
        model._clippingPlanes =
          tilesetClippingPlanes.enabled && this._tile._isClipped
            ? tilesetClippingPlanes
            : undefined;
      }

      // If the model references a different ClippingPlaneCollection due to the tileset's collection being replaced with a
      // ClippingPlaneCollection that gives this tile the same clipping status, update the model to use the new ClippingPlaneCollection.
      if (
        defined(tilesetClippingPlanes) &&
        defined(model._clippingPlanes) &&
        model._clippingPlanes !== tilesetClippingPlanes
      ) {
        model._clippingPlanes = tilesetClippingPlanes;
      }
    }

    this._modelInstanceCollection.update(frameState);

    // If any commands were pushed, add derived commands
    var commandEnd = frameState.commandList.length;
    if (
      commandStart < commandEnd &&
      (frameState.passes.render || frameState.passes.pick)
    ) {
      this._batchTable.addDerivedCommands(frameState, commandStart, false);
    }
  };

  Instanced3DModel3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Instanced3DModel3DTileContent.prototype.destroy = function () {
    this._modelInstanceCollection =
      this._modelInstanceCollection && this._modelInstanceCollection.destroy();
    this._batchTable = this._batchTable && this._batchTable.destroy();

    return destroyObject(this);
  };

  /**
   * The refinement approach for a tile.
   * <p>
   * See the {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification#refinement|Refinement}
   * in the 3D Tiles spec.
   * </p>
   *
   * @enum {Number}
   *
   * @private
   */
  var Cesium3DTileRefine = {
    /**
     * Render this tile and, if it doesn't meet the screen space error, also refine to its children.
     *
     * @type {Number}
     * @constant
     */
    ADD: 0,

    /**
     * Render this tile or, if it doesn't meet the screen space error, refine to its descendants instead.
     *
     * @type {Number}
     * @constant
     */
    REPLACE: 1,
  };
  var Cesium3DTileRefine$1 = Object.freeze(Cesium3DTileRefine);

  var DecodingState = {
    NEEDS_DECODE: 0,
    DECODING: 1,
    READY: 2,
    FAILED: 3,
  };

  /**
   * Represents the contents of a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/PointCloud|Point Cloud}
   * tile. Used internally by {@link PointCloud3DTileContent} and {@link TimeDynamicPointCloud}.
   *
   * @alias PointCloud
   * @constructor
   *
   * @see PointCloud3DTileContent
   * @see TimeDynamicPointCloud
   *
   * @private
   */
  function PointCloud(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.arrayBuffer", options.arrayBuffer);
    //>>includeEnd('debug');

    // Hold onto the payload until the render resources are created
    this._parsedContent = undefined;

    this._drawCommand = undefined;
    this._isTranslucent = false;
    this._styleTranslucent = false;
    this._constantColor = Color.clone(Color.DARKGRAY);
    this._highlightColor = Color.clone(Color.WHITE);
    this._pointSize = 1.0;

    this._rtcCenter = undefined;
    this._quantizedVolumeScale = undefined;
    this._quantizedVolumeOffset = undefined;

    // These values are used to regenerate the shader when the style changes
    this._styleableShaderAttributes = undefined;
    this._isQuantized = false;
    this._isOctEncoded16P = false;
    this._isRGB565 = false;
    this._hasColors = false;
    this._hasNormals = false;
    this._hasBatchIds = false;

    // Draco
    this._decodingState = DecodingState.READY;
    this._dequantizeInShader = true;
    this._isQuantizedDraco = false;
    this._isOctEncodedDraco = false;
    this._quantizedRange = 0.0;
    this._octEncodedRange = 0.0;

    // Use per-point normals to hide back-facing points.
    this.backFaceCulling = false;
    this._backFaceCulling = false;

    // Whether to enable normal shading
    this.normalShading = true;
    this._normalShading = true;

    this._opaqueRenderState = undefined;
    this._translucentRenderState = undefined;

    this._mode = undefined;

    this._ready = false;
    this._readyPromise = when.defer();
    this._pointsLength = 0;
    this._geometryByteLength = 0;

    this._vertexShaderLoaded = options.vertexShaderLoaded;
    this._fragmentShaderLoaded = options.fragmentShaderLoaded;
    this._uniformMapLoaded = options.uniformMapLoaded;
    this._batchTableLoaded = options.batchTableLoaded;
    this._pickIdLoaded = options.pickIdLoaded;
    this._opaquePass = defaultValue(options.opaquePass, Pass$1.OPAQUE);
    this._cull = defaultValue(options.cull, true);

    this.style = undefined;
    this._style = undefined;
    this.styleDirty = false;

    this.modelMatrix = Matrix4.clone(Matrix4.IDENTITY);
    this._modelMatrix = Matrix4.clone(Matrix4.IDENTITY);

    this.time = 0.0; // For styling
    this.shadows = ShadowMode$1.ENABLED;
    this._boundingSphere = undefined;

    this.clippingPlanes = undefined;
    this.isClipped = false;
    this.clippingPlanesDirty = false;
    // If defined, use this matrix to position the clipping planes instead of the modelMatrix.
    // This is so that when point clouds are part of a tileset they all get clipped relative
    // to the root tile.
    this.clippingPlanesOriginMatrix = undefined;

    this.attenuation = false;
    this._attenuation = false;

    // Options for geometric error based attenuation
    this.geometricError = 0.0;
    this.geometricErrorScale = 1.0;
    this.maximumAttenuation = this._pointSize;

    initialize$6(this, options);
  }

  Object.defineProperties(PointCloud.prototype, {
    pointsLength: {
      get: function () {
        return this._pointsLength;
      },
    },

    geometryByteLength: {
      get: function () {
        return this._geometryByteLength;
      },
    },

    ready: {
      get: function () {
        return this._ready;
      },
    },

    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    color: {
      get: function () {
        return Color.clone(this._highlightColor);
      },
      set: function (value) {
        this._highlightColor = Color.clone(value, this._highlightColor);
      },
    },

    boundingSphere: {
      get: function () {
        if (defined(this._drawCommand)) {
          return this._drawCommand.boundingVolume;
        }
        return undefined;
      },
      set: function (value) {
        this._boundingSphere = BoundingSphere.clone(value, this._boundingSphere);
      },
    },
  });

  var sizeOfUint32$7 = Uint32Array.BYTES_PER_ELEMENT;

  function initialize$6(pointCloud, options) {
    var arrayBuffer = options.arrayBuffer;
    var byteOffset = defaultValue(options.byteOffset, 0);

    var uint8Array = new Uint8Array(arrayBuffer);
    var view = new DataView(arrayBuffer);
    byteOffset += sizeOfUint32$7; // Skip magic

    var version = view.getUint32(byteOffset, true);
    if (version !== 1) {
      throw new RuntimeError(
        "Only Point Cloud tile version 1 is supported.  Version " +
          version +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$7;

    // Skip byteLength
    byteOffset += sizeOfUint32$7;

    var featureTableJsonByteLength = view.getUint32(byteOffset, true);
    if (featureTableJsonByteLength === 0) {
      throw new RuntimeError(
        "Feature table must have a byte length greater than zero"
      );
    }
    byteOffset += sizeOfUint32$7;

    var featureTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$7;

    var batchTableJsonByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$7;
    var batchTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$7;

    var featureTableString = getStringFromTypedArray(
      uint8Array,
      byteOffset,
      featureTableJsonByteLength
    );
    var featureTableJson = JSON.parse(featureTableString);
    byteOffset += featureTableJsonByteLength;

    var featureTableBinary = new Uint8Array(
      arrayBuffer,
      byteOffset,
      featureTableBinaryByteLength
    );
    byteOffset += featureTableBinaryByteLength;

    // Get the batch table JSON and binary
    var batchTableJson;
    var batchTableBinary;
    if (batchTableJsonByteLength > 0) {
      // Has a batch table JSON
      var batchTableString = getStringFromTypedArray(
        uint8Array,
        byteOffset,
        batchTableJsonByteLength
      );
      batchTableJson = JSON.parse(batchTableString);
      byteOffset += batchTableJsonByteLength;

      if (batchTableBinaryByteLength > 0) {
        // Has a batch table binary
        batchTableBinary = new Uint8Array(
          arrayBuffer,
          byteOffset,
          batchTableBinaryByteLength
        );
        byteOffset += batchTableBinaryByteLength;
      }
    }

    var featureTable = new Cesium3DTileFeatureTable(
      featureTableJson,
      featureTableBinary
    );

    var pointsLength = featureTable.getGlobalProperty("POINTS_LENGTH");
    featureTable.featuresLength = pointsLength;

    if (!defined(pointsLength)) {
      throw new RuntimeError(
        "Feature table global property: POINTS_LENGTH must be defined"
      );
    }

    var rtcCenter = featureTable.getGlobalProperty(
      "RTC_CENTER",
      ComponentDatatype$1.FLOAT,
      3
    );
    if (defined(rtcCenter)) {
      pointCloud._rtcCenter = Cartesian3.unpack(rtcCenter);
    }

    var positions;
    var colors;
    var normals;
    var batchIds;

    var hasPositions = false;
    var hasColors = false;
    var hasNormals = false;
    var hasBatchIds = false;

    var isQuantized = false;
    var isTranslucent = false;
    var isRGB565 = false;
    var isOctEncoded16P = false;

    var dracoBuffer;
    var dracoFeatureTableProperties;
    var dracoBatchTableProperties;

    var featureTableDraco = defined(featureTableJson.extensions)
      ? featureTableJson.extensions["3DTILES_draco_point_compression"]
      : undefined;
    var batchTableDraco =
      defined(batchTableJson) && defined(batchTableJson.extensions)
        ? batchTableJson.extensions["3DTILES_draco_point_compression"]
        : undefined;

    if (defined(batchTableDraco)) {
      dracoBatchTableProperties = batchTableDraco.properties;
    }

    if (defined(featureTableDraco)) {
      dracoFeatureTableProperties = featureTableDraco.properties;
      var dracoByteOffset = featureTableDraco.byteOffset;
      var dracoByteLength = featureTableDraco.byteLength;
      if (
        !defined(dracoFeatureTableProperties) ||
        !defined(dracoByteOffset) ||
        !defined(dracoByteLength)
      ) {
        throw new RuntimeError(
          "Draco properties, byteOffset, and byteLength must be defined"
        );
      }
      dracoBuffer = arraySlice(
        featureTableBinary,
        dracoByteOffset,
        dracoByteOffset + dracoByteLength
      );
      hasPositions = defined(dracoFeatureTableProperties.POSITION);
      hasColors =
        defined(dracoFeatureTableProperties.RGB) ||
        defined(dracoFeatureTableProperties.RGBA);
      hasNormals = defined(dracoFeatureTableProperties.NORMAL);
      hasBatchIds = defined(dracoFeatureTableProperties.BATCH_ID);
      isTranslucent = defined(dracoFeatureTableProperties.RGBA);
      pointCloud._decodingState = DecodingState.NEEDS_DECODE;
    }

    var draco;
    if (defined(dracoBuffer)) {
      draco = {
        buffer: dracoBuffer,
        featureTableProperties: dracoFeatureTableProperties,
        batchTableProperties: dracoBatchTableProperties,
        properties: combine(
          dracoFeatureTableProperties,
          dracoBatchTableProperties
        ),
        dequantizeInShader: pointCloud._dequantizeInShader,
      };
    }

    if (!hasPositions) {
      if (defined(featureTableJson.POSITION)) {
        positions = featureTable.getPropertyArray(
          "POSITION",
          ComponentDatatype$1.FLOAT,
          3
        );
        hasPositions = true;
      } else if (defined(featureTableJson.POSITION_QUANTIZED)) {
        positions = featureTable.getPropertyArray(
          "POSITION_QUANTIZED",
          ComponentDatatype$1.UNSIGNED_SHORT,
          3
        );
        isQuantized = true;
        hasPositions = true;

        var quantizedVolumeScale = featureTable.getGlobalProperty(
          "QUANTIZED_VOLUME_SCALE",
          ComponentDatatype$1.FLOAT,
          3
        );
        if (!defined(quantizedVolumeScale)) {
          throw new RuntimeError(
            "Global property: QUANTIZED_VOLUME_SCALE must be defined for quantized positions."
          );
        }
        pointCloud._quantizedVolumeScale = Cartesian3.unpack(
          quantizedVolumeScale
        );
        pointCloud._quantizedRange = (1 << 16) - 1;

        var quantizedVolumeOffset = featureTable.getGlobalProperty(
          "QUANTIZED_VOLUME_OFFSET",
          ComponentDatatype$1.FLOAT,
          3
        );
        if (!defined(quantizedVolumeOffset)) {
          throw new RuntimeError(
            "Global property: QUANTIZED_VOLUME_OFFSET must be defined for quantized positions."
          );
        }
        pointCloud._quantizedVolumeOffset = Cartesian3.unpack(
          quantizedVolumeOffset
        );
      }
    }

    if (!hasColors) {
      if (defined(featureTableJson.RGBA)) {
        colors = featureTable.getPropertyArray(
          "RGBA",
          ComponentDatatype$1.UNSIGNED_BYTE,
          4
        );
        isTranslucent = true;
        hasColors = true;
      } else if (defined(featureTableJson.RGB)) {
        colors = featureTable.getPropertyArray(
          "RGB",
          ComponentDatatype$1.UNSIGNED_BYTE,
          3
        );
        hasColors = true;
      } else if (defined(featureTableJson.RGB565)) {
        colors = featureTable.getPropertyArray(
          "RGB565",
          ComponentDatatype$1.UNSIGNED_SHORT,
          1
        );
        isRGB565 = true;
        hasColors = true;
      }
    }

    if (!hasNormals) {
      if (defined(featureTableJson.NORMAL)) {
        normals = featureTable.getPropertyArray(
          "NORMAL",
          ComponentDatatype$1.FLOAT,
          3
        );
        hasNormals = true;
      } else if (defined(featureTableJson.NORMAL_OCT16P)) {
        normals = featureTable.getPropertyArray(
          "NORMAL_OCT16P",
          ComponentDatatype$1.UNSIGNED_BYTE,
          2
        );
        isOctEncoded16P = true;
        hasNormals = true;
      }
    }

    if (!hasBatchIds) {
      if (defined(featureTableJson.BATCH_ID)) {
        batchIds = featureTable.getPropertyArray(
          "BATCH_ID",
          ComponentDatatype$1.UNSIGNED_SHORT,
          1
        );
        hasBatchIds = true;
      }
    }

    if (!hasPositions) {
      throw new RuntimeError(
        "Either POSITION or POSITION_QUANTIZED must be defined."
      );
    }

    if (defined(featureTableJson.CONSTANT_RGBA)) {
      var constantRGBA = featureTable.getGlobalProperty(
        "CONSTANT_RGBA",
        ComponentDatatype$1.UNSIGNED_BYTE,
        4
      );
      pointCloud._constantColor = Color.fromBytes(
        constantRGBA[0],
        constantRGBA[1],
        constantRGBA[2],
        constantRGBA[3],
        pointCloud._constantColor
      );
    }

    if (hasBatchIds) {
      var batchLength = featureTable.getGlobalProperty("BATCH_LENGTH");
      if (!defined(batchLength)) {
        throw new RuntimeError(
          "Global property: BATCH_LENGTH must be defined when BATCH_ID is defined."
        );
      }

      if (defined(batchTableBinary)) {
        // Copy the batchTableBinary section and let the underlying ArrayBuffer be freed
        batchTableBinary = new Uint8Array(batchTableBinary);
      }

      if (defined(pointCloud._batchTableLoaded)) {
        pointCloud._batchTableLoaded(
          batchLength,
          batchTableJson,
          batchTableBinary
        );
      }
    }

    // If points are not batched and there are per-point properties, use these properties for styling purposes
    var styleableProperties;
    if (!hasBatchIds && defined(batchTableBinary)) {
      styleableProperties = Cesium3DTileBatchTable.getBinaryProperties(
        pointsLength,
        batchTableJson,
        batchTableBinary
      );
    }

    pointCloud._parsedContent = {
      positions: positions,
      colors: colors,
      normals: normals,
      batchIds: batchIds,
      styleableProperties: styleableProperties,
      draco: draco,
    };
    pointCloud._pointsLength = pointsLength;
    pointCloud._isQuantized = isQuantized;
    pointCloud._isOctEncoded16P = isOctEncoded16P;
    pointCloud._isRGB565 = isRGB565;
    pointCloud._isTranslucent = isTranslucent;
    pointCloud._hasColors = hasColors;
    pointCloud._hasNormals = hasNormals;
    pointCloud._hasBatchIds = hasBatchIds;
  }

  var scratchMin$2 = new Cartesian3();
  var scratchMax$2 = new Cartesian3();
  var scratchPosition$7 = new Cartesian3();
  var randomValues;

  function getRandomValues(samplesLength) {
    // Use same random values across all runs
    if (!defined(randomValues)) {
      CesiumMath.setRandomNumberSeed(0);
      randomValues = new Array(samplesLength);
      for (var i = 0; i < samplesLength; ++i) {
        randomValues[i] = CesiumMath.nextRandomNumber();
      }
    }
    return randomValues;
  }

  function computeApproximateBoundingSphereFromPositions(positions) {
    var maximumSamplesLength = 20;
    var pointsLength = positions.length / 3;
    var samplesLength = Math.min(pointsLength, maximumSamplesLength);
    var randomValues = getRandomValues(maximumSamplesLength);
    var maxValue = Number.MAX_VALUE;
    var minValue = -Number.MAX_VALUE;
    var min = Cartesian3.fromElements(maxValue, maxValue, maxValue, scratchMin$2);
    var max = Cartesian3.fromElements(minValue, minValue, minValue, scratchMax$2);
    for (var i = 0; i < samplesLength; ++i) {
      var index = Math.floor(randomValues[i] * pointsLength);
      var position = Cartesian3.unpack(positions, index * 3, scratchPosition$7);
      Cartesian3.minimumByComponent(min, position, min);
      Cartesian3.maximumByComponent(max, position, max);
    }

    var boundingSphere = BoundingSphere.fromCornerPoints(min, max);
    boundingSphere.radius += CesiumMath.EPSILON2; // To avoid radius of zero
    return boundingSphere;
  }

  function prepareVertexAttribute(typedArray, name) {
    // WebGL does not support UNSIGNED_INT, INT, or DOUBLE vertex attributes. Convert these to FLOAT.
    var componentDatatype = ComponentDatatype$1.fromTypedArray(typedArray);
    if (
      componentDatatype === ComponentDatatype$1.INT ||
      componentDatatype === ComponentDatatype$1.UNSIGNED_INT ||
      componentDatatype === ComponentDatatype$1.DOUBLE
    ) {
      oneTimeWarning(
        "Cast pnts property to floats",
        'Point cloud property "' +
          name +
          '" will be casted to a float array because INT, UNSIGNED_INT, and DOUBLE are not valid WebGL vertex attribute types. Some precision may be lost.'
      );
      return new Float32Array(typedArray);
    }
    return typedArray;
  }

  var scratchPointSizeAndTimeAndGeometricErrorAndDepthMultiplier = new Cartesian4();
  var scratchQuantizedVolumeScaleAndOctEncodedRange = new Cartesian4();
  var scratchColor$5 = new Color();

  var positionLocation = 0;
  var colorLocation = 1;
  var normalLocation = 2;
  var batchIdLocation = 3;
  var numberOfAttributes = 4;

  var scratchClippingPlaneMatrix$1 = new Matrix4();

  function createResources$2(pointCloud, frameState) {
    var context = frameState.context;
    var parsedContent = pointCloud._parsedContent;
    var pointsLength = pointCloud._pointsLength;
    var positions = parsedContent.positions;
    var colors = parsedContent.colors;
    var normals = parsedContent.normals;
    var batchIds = parsedContent.batchIds;
    var styleableProperties = parsedContent.styleableProperties;
    var hasStyleableProperties = defined(styleableProperties);
    var isQuantized = pointCloud._isQuantized;
    var isQuantizedDraco = pointCloud._isQuantizedDraco;
    var isOctEncoded16P = pointCloud._isOctEncoded16P;
    var isOctEncodedDraco = pointCloud._isOctEncodedDraco;
    var quantizedRange = pointCloud._quantizedRange;
    var octEncodedRange = pointCloud._octEncodedRange;
    var isRGB565 = pointCloud._isRGB565;
    var isTranslucent = pointCloud._isTranslucent;
    var hasColors = pointCloud._hasColors;
    var hasNormals = pointCloud._hasNormals;
    var hasBatchIds = pointCloud._hasBatchIds;

    var componentsPerAttribute;
    var componentDatatype;

    var styleableVertexAttributes = [];
    var styleableShaderAttributes = {};
    pointCloud._styleableShaderAttributes = styleableShaderAttributes;

    if (hasStyleableProperties) {
      var attributeLocation = numberOfAttributes;

      for (var name in styleableProperties) {
        if (styleableProperties.hasOwnProperty(name)) {
          var property = styleableProperties[name];
          var typedArray = prepareVertexAttribute(property.typedArray, name);
          componentsPerAttribute = property.componentCount;
          componentDatatype = ComponentDatatype$1.fromTypedArray(typedArray);

          var vertexBuffer = Buffer$1.createVertexBuffer({
            context: context,
            typedArray: typedArray,
            usage: BufferUsage$1.STATIC_DRAW,
          });

          pointCloud._geometryByteLength += vertexBuffer.sizeInBytes;

          var vertexAttribute = {
            index: attributeLocation,
            vertexBuffer: vertexBuffer,
            componentsPerAttribute: componentsPerAttribute,
            componentDatatype: componentDatatype,
            normalize: false,
            offsetInBytes: 0,
            strideInBytes: 0,
          };

          styleableVertexAttributes.push(vertexAttribute);
          styleableShaderAttributes[name] = {
            location: attributeLocation,
            componentCount: componentsPerAttribute,
          };
          ++attributeLocation;
        }
      }
    }

    var positionsVertexBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: positions,
      usage: BufferUsage$1.STATIC_DRAW,
    });
    pointCloud._geometryByteLength += positionsVertexBuffer.sizeInBytes;

    var colorsVertexBuffer;
    if (hasColors) {
      colorsVertexBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: colors,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      pointCloud._geometryByteLength += colorsVertexBuffer.sizeInBytes;
    }

    var normalsVertexBuffer;
    if (hasNormals) {
      normalsVertexBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: normals,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      pointCloud._geometryByteLength += normalsVertexBuffer.sizeInBytes;
    }

    var batchIdsVertexBuffer;
    if (hasBatchIds) {
      batchIds = prepareVertexAttribute(batchIds, "batchIds");
      batchIdsVertexBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: batchIds,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      pointCloud._geometryByteLength += batchIdsVertexBuffer.sizeInBytes;
    }

    var attributes = [];

    if (isQuantized) {
      componentDatatype = ComponentDatatype$1.UNSIGNED_SHORT;
    } else if (isQuantizedDraco) {
      componentDatatype =
        quantizedRange <= 255
          ? ComponentDatatype$1.UNSIGNED_BYTE
          : ComponentDatatype$1.UNSIGNED_SHORT;
    } else {
      componentDatatype = ComponentDatatype$1.FLOAT;
    }

    attributes.push({
      index: positionLocation,
      vertexBuffer: positionsVertexBuffer,
      componentsPerAttribute: 3,
      componentDatatype: componentDatatype,
      normalize: false,
      offsetInBytes: 0,
      strideInBytes: 0,
    });

    if (pointCloud._cull) {
      if (isQuantized || isQuantizedDraco) {
        pointCloud._boundingSphere = BoundingSphere.fromCornerPoints(
          Cartesian3.ZERO,
          pointCloud._quantizedVolumeScale
        );
      } else {
        pointCloud._boundingSphere = computeApproximateBoundingSphereFromPositions(
          positions
        );
      }
    }

    if (hasColors) {
      if (isRGB565) {
        attributes.push({
          index: colorLocation,
          vertexBuffer: colorsVertexBuffer,
          componentsPerAttribute: 1,
          componentDatatype: ComponentDatatype$1.UNSIGNED_SHORT,
          normalize: false,
          offsetInBytes: 0,
          strideInBytes: 0,
        });
      } else {
        var colorComponentsPerAttribute = isTranslucent ? 4 : 3;
        attributes.push({
          index: colorLocation,
          vertexBuffer: colorsVertexBuffer,
          componentsPerAttribute: colorComponentsPerAttribute,
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
          normalize: true,
          offsetInBytes: 0,
          strideInBytes: 0,
        });
      }
    }

    if (hasNormals) {
      if (isOctEncoded16P) {
        componentsPerAttribute = 2;
        componentDatatype = ComponentDatatype$1.UNSIGNED_BYTE;
      } else if (isOctEncodedDraco) {
        componentsPerAttribute = 2;
        componentDatatype =
          octEncodedRange <= 255
            ? ComponentDatatype$1.UNSIGNED_BYTE
            : ComponentDatatype$1.UNSIGNED_SHORT;
      } else {
        componentsPerAttribute = 3;
        componentDatatype = ComponentDatatype$1.FLOAT;
      }
      attributes.push({
        index: normalLocation,
        vertexBuffer: normalsVertexBuffer,
        componentsPerAttribute: componentsPerAttribute,
        componentDatatype: componentDatatype,
        normalize: false,
        offsetInBytes: 0,
        strideInBytes: 0,
      });
    }

    if (hasBatchIds) {
      attributes.push({
        index: batchIdLocation,
        vertexBuffer: batchIdsVertexBuffer,
        componentsPerAttribute: 1,
        componentDatatype: ComponentDatatype$1.fromTypedArray(batchIds),
        normalize: false,
        offsetInBytes: 0,
        strideInBytes: 0,
      });
    }

    if (hasStyleableProperties) {
      attributes = attributes.concat(styleableVertexAttributes);
    }

    var vertexArray = new VertexArray({
      context: context,
      attributes: attributes,
    });

    var opaqueRenderState = {
      depthTest: {
        enabled: true,
      },
    };

    if (pointCloud._opaquePass === Pass$1.CESIUM_3D_TILE) {
      opaqueRenderState.stencilTest = StencilConstants$1.setCesium3DTileBit();
      opaqueRenderState.stencilMask = StencilConstants$1.CESIUM_3D_TILE_MASK;
    }

    pointCloud._opaqueRenderState = RenderState.fromCache(opaqueRenderState);

    pointCloud._translucentRenderState = RenderState.fromCache({
      depthTest: {
        enabled: true,
      },
      depthMask: false,
      blending: BlendingState$1.ALPHA_BLEND,
    });

    pointCloud._drawCommand = new DrawCommand({
      boundingVolume: new BoundingSphere(),
      cull: pointCloud._cull,
      modelMatrix: new Matrix4(),
      primitiveType: PrimitiveType$1.POINTS,
      vertexArray: vertexArray,
      count: pointsLength,
      shaderProgram: undefined, // Updated in createShaders
      uniformMap: undefined, // Updated in createShaders
      renderState: isTranslucent
        ? pointCloud._translucentRenderState
        : pointCloud._opaqueRenderState,
      pass: isTranslucent ? Pass$1.TRANSLUCENT : pointCloud._opaquePass,
      owner: pointCloud,
      castShadows: false,
      receiveShadows: false,
      pickId: pointCloud._pickIdLoaded(),
    });
  }

  function createUniformMap$2(pointCloud, frameState) {
    var context = frameState.context;
    var isQuantized = pointCloud._isQuantized;
    var isQuantizedDraco = pointCloud._isQuantizedDraco;
    var isOctEncodedDraco = pointCloud._isOctEncodedDraco;

    var uniformMap = {
      u_pointSizeAndTimeAndGeometricErrorAndDepthMultiplier: function () {
        var scratch = scratchPointSizeAndTimeAndGeometricErrorAndDepthMultiplier;
        scratch.x = pointCloud._attenuation
          ? pointCloud.maximumAttenuation
          : pointCloud._pointSize;
        scratch.x *= frameState.pixelRatio;

        scratch.y = pointCloud.time;

        if (pointCloud._attenuation) {
          var frustum = frameState.camera.frustum;
          var depthMultiplier;
          // Attenuation is maximumAttenuation in 2D/ortho
          if (
            frameState.mode === SceneMode$1.SCENE2D ||
            frustum instanceof OrthographicFrustum
          ) {
            depthMultiplier = Number.POSITIVE_INFINITY;
          } else {
            depthMultiplier =
              context.drawingBufferHeight /
              frameState.camera.frustum.sseDenominator;
          }

          scratch.z = pointCloud.geometricError * pointCloud.geometricErrorScale;
          scratch.w = depthMultiplier;
        }

        return scratch;
      },
      u_highlightColor: function () {
        return pointCloud._highlightColor;
      },
      u_constantColor: function () {
        return pointCloud._constantColor;
      },
      u_clippingPlanes: function () {
        var clippingPlanes = pointCloud.clippingPlanes;
        var isClipped = pointCloud.isClipped;
        return isClipped ? clippingPlanes.texture : context.defaultTexture;
      },
      u_clippingPlanesEdgeStyle: function () {
        var clippingPlanes = pointCloud.clippingPlanes;
        if (!defined(clippingPlanes)) {
          return Color.TRANSPARENT;
        }

        var style = Color.clone(clippingPlanes.edgeColor, scratchColor$5);
        style.alpha = clippingPlanes.edgeWidth;
        return style;
      },
      u_clippingPlanesMatrix: function () {
        var clippingPlanes = pointCloud.clippingPlanes;
        if (!defined(clippingPlanes)) {
          return Matrix4.IDENTITY;
        }

        var clippingPlanesOriginMatrix = defaultValue(
          pointCloud.clippingPlanesOriginMatrix,
          pointCloud._modelMatrix
        );
        Matrix4.multiply(
          context.uniformState.view3D,
          clippingPlanesOriginMatrix,
          scratchClippingPlaneMatrix$1
        );
        return Matrix4.multiply(
          scratchClippingPlaneMatrix$1,
          clippingPlanes.modelMatrix,
          scratchClippingPlaneMatrix$1
        );
      },
    };

    if (isQuantized || isQuantizedDraco || isOctEncodedDraco) {
      uniformMap = combine(uniformMap, {
        u_quantizedVolumeScaleAndOctEncodedRange: function () {
          var scratch = scratchQuantizedVolumeScaleAndOctEncodedRange;
          if (defined(pointCloud._quantizedVolumeScale)) {
            var scale = Cartesian3.clone(
              pointCloud._quantizedVolumeScale,
              scratch
            );
            Cartesian3.divideByScalar(scale, pointCloud._quantizedRange, scratch);
          }
          scratch.w = pointCloud._octEncodedRange;
          return scratch;
        },
      });
    }

    if (defined(pointCloud._uniformMapLoaded)) {
      uniformMap = pointCloud._uniformMapLoaded(uniformMap);
    }

    pointCloud._drawCommand.uniformMap = uniformMap;
  }

  function getStyleablePropertyIds(source, propertyIds) {
    // Get all the property IDs used by this style
    var regex = /czm_3dtiles_property_(\d+)/g;
    var matches = regex.exec(source);
    while (matches !== null) {
      var id = parseInt(matches[1]);
      if (propertyIds.indexOf(id) === -1) {
        propertyIds.push(id);
      }
      matches = regex.exec(source);
    }
  }

  function getBuiltinPropertyNames(source, propertyNames) {
    // Get all the builtin property names used by this style
    var regex = /czm_3dtiles_builtin_property_(\w+)/g;
    var matches = regex.exec(source);
    while (matches !== null) {
      var name = matches[1];
      if (propertyNames.indexOf(name) === -1) {
        propertyNames.push(name);
      }
      matches = regex.exec(source);
    }
  }

  function getVertexAttribute(vertexArray, index) {
    var numberOfAttributes = vertexArray.numberOfAttributes;
    for (var i = 0; i < numberOfAttributes; ++i) {
      var attribute = vertexArray.getAttribute(i);
      if (attribute.index === index) {
        return attribute;
      }
    }
  }

  var builtinPropertyNameMap = {
    POSITION: "czm_3dtiles_builtin_property_POSITION",
    POSITION_ABSOLUTE: "czm_3dtiles_builtin_property_POSITION_ABSOLUTE",
    COLOR: "czm_3dtiles_builtin_property_COLOR",
    NORMAL: "czm_3dtiles_builtin_property_NORMAL",
  };

  function modifyStyleFunction(source) {
    // Edit the function header to accept the point position, color, and normal
    var functionHeader =
      "(" +
      "vec3 czm_3dtiles_builtin_property_POSITION, " +
      "vec3 czm_3dtiles_builtin_property_POSITION_ABSOLUTE, " +
      "vec4 czm_3dtiles_builtin_property_COLOR, " +
      "vec3 czm_3dtiles_builtin_property_NORMAL" +
      ")";

    return source.replace("()", functionHeader);
  }

  function createShaders$1(pointCloud, frameState, style) {
    var i;
    var name;
    var attribute;

    var context = frameState.context;
    var hasStyle = defined(style);
    var isQuantized = pointCloud._isQuantized;
    var isQuantizedDraco = pointCloud._isQuantizedDraco;
    var isOctEncoded16P = pointCloud._isOctEncoded16P;
    var isOctEncodedDraco = pointCloud._isOctEncodedDraco;
    var isRGB565 = pointCloud._isRGB565;
    var isTranslucent = pointCloud._isTranslucent;
    var hasColors = pointCloud._hasColors;
    var hasNormals = pointCloud._hasNormals;
    var hasBatchIds = pointCloud._hasBatchIds;
    var backFaceCulling = pointCloud._backFaceCulling;
    var normalShading = pointCloud._normalShading;
    var vertexArray = pointCloud._drawCommand.vertexArray;
    var clippingPlanes = pointCloud.clippingPlanes;
    var attenuation = pointCloud._attenuation;

    var colorStyleFunction;
    var showStyleFunction;
    var pointSizeStyleFunction;
    var styleTranslucent = isTranslucent;

    var propertyNameMap = clone(builtinPropertyNameMap);
    var propertyIdToAttributeMap = {};
    var styleableShaderAttributes = pointCloud._styleableShaderAttributes;
    for (name in styleableShaderAttributes) {
      if (styleableShaderAttributes.hasOwnProperty(name)) {
        attribute = styleableShaderAttributes[name];
        propertyNameMap[name] = "czm_3dtiles_property_" + attribute.location;
        propertyIdToAttributeMap[attribute.location] = attribute;
      }
    }

    if (hasStyle) {
      var shaderState = {
        translucent: false,
      };
      colorStyleFunction = style.getColorShaderFunction(
        "getColorFromStyle",
        propertyNameMap,
        shaderState
      );
      showStyleFunction = style.getShowShaderFunction(
        "getShowFromStyle",
        propertyNameMap,
        shaderState
      );
      pointSizeStyleFunction = style.getPointSizeShaderFunction(
        "getPointSizeFromStyle",
        propertyNameMap,
        shaderState
      );
      if (defined(colorStyleFunction) && shaderState.translucent) {
        styleTranslucent = true;
      }
    }

    pointCloud._styleTranslucent = styleTranslucent;

    var hasColorStyle = defined(colorStyleFunction);
    var hasShowStyle = defined(showStyleFunction);
    var hasPointSizeStyle = defined(pointSizeStyleFunction);
    var hasClippedContent = pointCloud.isClipped;

    // Get the properties in use by the style
    var styleablePropertyIds = [];
    var builtinPropertyNames = [];

    if (hasColorStyle) {
      getStyleablePropertyIds(colorStyleFunction, styleablePropertyIds);
      getBuiltinPropertyNames(colorStyleFunction, builtinPropertyNames);
      colorStyleFunction = modifyStyleFunction(colorStyleFunction);
    }
    if (hasShowStyle) {
      getStyleablePropertyIds(showStyleFunction, styleablePropertyIds);
      getBuiltinPropertyNames(showStyleFunction, builtinPropertyNames);
      showStyleFunction = modifyStyleFunction(showStyleFunction);
    }
    if (hasPointSizeStyle) {
      getStyleablePropertyIds(pointSizeStyleFunction, styleablePropertyIds);
      getBuiltinPropertyNames(pointSizeStyleFunction, builtinPropertyNames);
      pointSizeStyleFunction = modifyStyleFunction(pointSizeStyleFunction);
    }

    var usesColorSemantic = builtinPropertyNames.indexOf("COLOR") >= 0;
    var usesNormalSemantic = builtinPropertyNames.indexOf("NORMAL") >= 0;

    if (usesNormalSemantic && !hasNormals) {
      throw new RuntimeError(
        "Style references the NORMAL semantic but the point cloud does not have normals"
      );
    }

    // Disable vertex attributes that aren't used in the style, enable attributes that are
    for (name in styleableShaderAttributes) {
      if (styleableShaderAttributes.hasOwnProperty(name)) {
        attribute = styleableShaderAttributes[name];
        var enabled = styleablePropertyIds.indexOf(attribute.location) >= 0;
        var vertexAttribute = getVertexAttribute(vertexArray, attribute.location);
        vertexAttribute.enabled = enabled;
      }
    }

    var usesColors = hasColors && (!hasColorStyle || usesColorSemantic);
    if (hasColors) {
      // Disable the color vertex attribute if the color style does not reference the color semantic
      var colorVertexAttribute = getVertexAttribute(vertexArray, colorLocation);
      colorVertexAttribute.enabled = usesColors;
    }

    var usesNormals =
      hasNormals && (normalShading || backFaceCulling || usesNormalSemantic);
    if (hasNormals) {
      // Disable the normal vertex attribute if normals are not used
      var normalVertexAttribute = getVertexAttribute(vertexArray, normalLocation);
      normalVertexAttribute.enabled = usesNormals;
    }

    var attributeLocations = {
      a_position: positionLocation,
    };
    if (usesColors) {
      attributeLocations.a_color = colorLocation;
    }
    if (usesNormals) {
      attributeLocations.a_normal = normalLocation;
    }
    if (hasBatchIds) {
      attributeLocations.a_batchId = batchIdLocation;
    }

    var attributeDeclarations = "";

    var length = styleablePropertyIds.length;
    for (i = 0; i < length; ++i) {
      var propertyId = styleablePropertyIds[i];
      attribute = propertyIdToAttributeMap[propertyId];
      var componentCount = attribute.componentCount;
      var attributeName = "czm_3dtiles_property_" + propertyId;
      var attributeType;
      if (componentCount === 1) {
        attributeType = "float";
      } else {
        attributeType = "vec" + componentCount;
      }

      attributeDeclarations +=
        "attribute " + attributeType + " " + attributeName + "; \n";
      attributeLocations[attributeName] = attribute.location;
    }

    createUniformMap$2(pointCloud, frameState);

    var vs =
      "attribute vec3 a_position; \n" +
      "varying vec4 v_color; \n" +
      "uniform vec4 u_pointSizeAndTimeAndGeometricErrorAndDepthMultiplier; \n" +
      "uniform vec4 u_constantColor; \n" +
      "uniform vec4 u_highlightColor; \n";
    vs += "float u_pointSize; \n" + "float u_time; \n";

    if (attenuation) {
      vs += "float u_geometricError; \n" + "float u_depthMultiplier; \n";
    }

    vs += attributeDeclarations;

    if (usesColors) {
      if (isTranslucent) {
        vs += "attribute vec4 a_color; \n";
      } else if (isRGB565) {
        vs +=
          "attribute float a_color; \n" +
          "const float SHIFT_RIGHT_11 = 1.0 / 2048.0; \n" +
          "const float SHIFT_RIGHT_5 = 1.0 / 32.0; \n" +
          "const float SHIFT_LEFT_11 = 2048.0; \n" +
          "const float SHIFT_LEFT_5 = 32.0; \n" +
          "const float NORMALIZE_6 = 1.0 / 64.0; \n" +
          "const float NORMALIZE_5 = 1.0 / 32.0; \n";
      } else {
        vs += "attribute vec3 a_color; \n";
      }
    }
    if (usesNormals) {
      if (isOctEncoded16P || isOctEncodedDraco) {
        vs += "attribute vec2 a_normal; \n";
      } else {
        vs += "attribute vec3 a_normal; \n";
      }
    }

    if (hasBatchIds) {
      vs += "attribute float a_batchId; \n";
    }

    if (isQuantized || isQuantizedDraco || isOctEncodedDraco) {
      vs += "uniform vec4 u_quantizedVolumeScaleAndOctEncodedRange; \n";
    }

    if (hasColorStyle) {
      vs += colorStyleFunction;
    }

    if (hasShowStyle) {
      vs += showStyleFunction;
    }

    if (hasPointSizeStyle) {
      vs += pointSizeStyleFunction;
    }

    vs +=
      "void main() \n" +
      "{ \n" +
      "    u_pointSize = u_pointSizeAndTimeAndGeometricErrorAndDepthMultiplier.x; \n" +
      "    u_time = u_pointSizeAndTimeAndGeometricErrorAndDepthMultiplier.y; \n";

    if (attenuation) {
      vs +=
        "    u_geometricError = u_pointSizeAndTimeAndGeometricErrorAndDepthMultiplier.z; \n" +
        "    u_depthMultiplier = u_pointSizeAndTimeAndGeometricErrorAndDepthMultiplier.w; \n";
    }

    if (usesColors) {
      if (isTranslucent) {
        vs += "    vec4 color = a_color; \n";
      } else if (isRGB565) {
        vs +=
          "    float compressed = a_color; \n" +
          "    float r = floor(compressed * SHIFT_RIGHT_11); \n" +
          "    compressed -= r * SHIFT_LEFT_11; \n" +
          "    float g = floor(compressed * SHIFT_RIGHT_5); \n" +
          "    compressed -= g * SHIFT_LEFT_5; \n" +
          "    float b = compressed; \n" +
          "    vec3 rgb = vec3(r * NORMALIZE_5, g * NORMALIZE_6, b * NORMALIZE_5); \n" +
          "    vec4 color = vec4(rgb, 1.0); \n";
      } else {
        vs += "    vec4 color = vec4(a_color, 1.0); \n";
      }
    } else {
      vs += "    vec4 color = u_constantColor; \n";
    }

    if (isQuantized || isQuantizedDraco) {
      vs +=
        "    vec3 position = a_position * u_quantizedVolumeScaleAndOctEncodedRange.xyz; \n";
    } else {
      vs += "    vec3 position = a_position; \n";
    }
    vs +=
      "    vec3 position_absolute = vec3(czm_model * vec4(position, 1.0)); \n";

    if (usesNormals) {
      if (isOctEncoded16P) {
        vs += "    vec3 normal = czm_octDecode(a_normal); \n";
      } else if (isOctEncodedDraco) {
        // Draco oct-encoding decodes to zxy order
        vs +=
          "    vec3 normal = czm_octDecode(a_normal, u_quantizedVolumeScaleAndOctEncodedRange.w).zxy; \n";
      } else {
        vs += "    vec3 normal = a_normal; \n";
      }
      vs += "    vec3 normalEC = czm_normal * normal; \n";
    } else {
      vs += "    vec3 normal = vec3(1.0); \n";
    }

    if (hasColorStyle) {
      vs +=
        "    color = getColorFromStyle(position, position_absolute, color, normal); \n";
    }

    if (hasShowStyle) {
      vs +=
        "    float show = float(getShowFromStyle(position, position_absolute, color, normal)); \n";
    }

    if (hasPointSizeStyle) {
      vs +=
        "    gl_PointSize = getPointSizeFromStyle(position, position_absolute, color, normal) * czm_pixelRatio; \n";
    } else if (attenuation) {
      vs +=
        "    vec4 positionEC = czm_modelView * vec4(position, 1.0); \n" +
        "    float depth = -positionEC.z; \n" +
        // compute SSE for this point
        "    gl_PointSize = min((u_geometricError / depth) * u_depthMultiplier, u_pointSize); \n";
    } else {
      vs += "    gl_PointSize = u_pointSize; \n";
    }

    vs += "    color = color * u_highlightColor; \n";

    if (usesNormals && normalShading) {
      vs +=
        "    float diffuseStrength = czm_getLambertDiffuse(czm_lightDirectionEC, normalEC); \n" +
        "    diffuseStrength = max(diffuseStrength, 0.4); \n" + // Apply some ambient lighting
        "    color.xyz *= diffuseStrength * czm_lightColor; \n";
    }

    vs +=
      "    v_color = color; \n" +
      "    gl_Position = czm_modelViewProjection * vec4(position, 1.0); \n";

    if (usesNormals && backFaceCulling) {
      vs +=
        "    float visible = step(-normalEC.z, 0.0); \n" +
        "    gl_Position *= visible; \n" +
        "    gl_PointSize *= visible; \n";
    }

    if (hasShowStyle) {
      vs +=
        "    gl_Position.w *= float(show); \n" +
        "    gl_PointSize *= float(show); \n";
    }

    vs += "} \n";

    var fs = "varying vec4 v_color; \n";

    if (hasClippedContent) {
      fs +=
        "uniform highp sampler2D u_clippingPlanes; \n" +
        "uniform mat4 u_clippingPlanesMatrix; \n" +
        "uniform vec4 u_clippingPlanesEdgeStyle; \n";
      fs += "\n";
      fs += getClippingFunction(clippingPlanes, context);
      fs += "\n";
    }

    fs +=
      "void main() \n" +
      "{ \n" +
      "    gl_FragColor = czm_gammaCorrect(v_color); \n";

    if (hasClippedContent) {
      fs += getClipAndStyleCode(
        "u_clippingPlanes",
        "u_clippingPlanesMatrix",
        "u_clippingPlanesEdgeStyle"
      );
    }

    fs += "} \n";

    if (defined(pointCloud._vertexShaderLoaded)) {
      vs = pointCloud._vertexShaderLoaded(vs);
    }

    if (defined(pointCloud._fragmentShaderLoaded)) {
      fs = pointCloud._fragmentShaderLoaded(fs);
    }

    var drawCommand = pointCloud._drawCommand;
    if (defined(drawCommand.shaderProgram)) {
      // Destroy the old shader
      drawCommand.shaderProgram.destroy();
    }
    drawCommand.shaderProgram = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations,
    });

    try {
      // Check if the shader compiles correctly. If not there is likely a syntax error with the style.
      drawCommand.shaderProgram._bind();
    } catch (error) {
      // Rephrase the error.
      throw new RuntimeError(
        "Error generating style shader: this may be caused by a type mismatch, index out-of-bounds, or other syntax error."
      );
    }
  }

  function decodeDraco(pointCloud, context) {
    if (pointCloud._decodingState === DecodingState.READY) {
      return false;
    }
    if (pointCloud._decodingState === DecodingState.NEEDS_DECODE) {
      var parsedContent = pointCloud._parsedContent;
      var draco = parsedContent.draco;
      var decodePromise = DracoLoader.decodePointCloud(draco, context);
      if (defined(decodePromise)) {
        pointCloud._decodingState = DecodingState.DECODING;
        decodePromise
          .then(function (result) {
            pointCloud._decodingState = DecodingState.READY;
            var decodedPositions = defined(result.POSITION)
              ? result.POSITION.array
              : undefined;
            var decodedRgb = defined(result.RGB) ? result.RGB.array : undefined;
            var decodedRgba = defined(result.RGBA)
              ? result.RGBA.array
              : undefined;
            var decodedNormals = defined(result.NORMAL)
              ? result.NORMAL.array
              : undefined;
            var decodedBatchIds = defined(result.BATCH_ID)
              ? result.BATCH_ID.array
              : undefined;
            var isQuantizedDraco =
              defined(decodedPositions) &&
              defined(result.POSITION.data.quantization);
            var isOctEncodedDraco =
              defined(decodedNormals) && defined(result.NORMAL.data.quantization);
            if (isQuantizedDraco) {
              // Draco quantization range == quantized volume scale - size in meters of the quantized volume
              // Internal quantized range is the range of values of the quantized data, e.g. 255 for 8-bit, 1023 for 10-bit, etc
              var quantization = result.POSITION.data.quantization;
              var range = quantization.range;
              pointCloud._quantizedVolumeScale = Cartesian3.fromElements(
                range,
                range,
                range
              );
              pointCloud._quantizedVolumeOffset = Cartesian3.unpack(
                quantization.minValues
              );
              pointCloud._quantizedRange =
                (1 << quantization.quantizationBits) - 1.0;
              pointCloud._isQuantizedDraco = true;
            }
            if (isOctEncodedDraco) {
              pointCloud._octEncodedRange =
                (1 << result.NORMAL.data.quantization.quantizationBits) - 1.0;
              pointCloud._isOctEncodedDraco = true;
            }
            var styleableProperties = parsedContent.styleableProperties;
            var batchTableProperties = draco.batchTableProperties;
            for (var name in batchTableProperties) {
              if (batchTableProperties.hasOwnProperty(name)) {
                var property = result[name];
                if (!defined(styleableProperties)) {
                  styleableProperties = {};
                }
                styleableProperties[name] = {
                  typedArray: property.array,
                  componentCount: property.data.componentsPerAttribute,
                };
              }
            }
            parsedContent.positions = defaultValue(
              decodedPositions,
              parsedContent.positions
            );
            parsedContent.colors = defaultValue(
              defaultValue(decodedRgba, decodedRgb),
              parsedContent.colors
            );
            parsedContent.normals = defaultValue(
              decodedNormals,
              parsedContent.normals
            );
            parsedContent.batchIds = defaultValue(
              decodedBatchIds,
              parsedContent.batchIds
            );
            parsedContent.styleableProperties = styleableProperties;
          })
          .otherwise(function (error) {
            pointCloud._decodingState = DecodingState.FAILED;
            pointCloud._readyPromise.reject(error);
          });
      }
    }
    return true;
  }

  var scratchComputedTranslation$2 = new Cartesian4();
  var scratchScale$5 = new Cartesian3();

  PointCloud.prototype.update = function (frameState) {
    var context = frameState.context;
    var decoding = decodeDraco(this, context);
    if (decoding) {
      return;
    }

    var shadersDirty = false;
    var modelMatrixDirty = !Matrix4.equals(this._modelMatrix, this.modelMatrix);

    if (this._mode !== frameState.mode) {
      this._mode = frameState.mode;
      modelMatrixDirty = true;
    }

    if (!defined(this._drawCommand)) {
      createResources$2(this, frameState);
      modelMatrixDirty = true;
      shadersDirty = true;
      this._ready = true;
      this._readyPromise.resolve(this);
      this._parsedContent = undefined; // Unload
    }

    if (modelMatrixDirty) {
      Matrix4.clone(this.modelMatrix, this._modelMatrix);
      var modelMatrix = this._drawCommand.modelMatrix;
      Matrix4.clone(this._modelMatrix, modelMatrix);

      if (defined(this._rtcCenter)) {
        Matrix4.multiplyByTranslation(modelMatrix, this._rtcCenter, modelMatrix);
      }
      if (defined(this._quantizedVolumeOffset)) {
        Matrix4.multiplyByTranslation(
          modelMatrix,
          this._quantizedVolumeOffset,
          modelMatrix
        );
      }

      if (frameState.mode !== SceneMode$1.SCENE3D) {
        var projection = frameState.mapProjection;
        var translation = Matrix4.getColumn(
          modelMatrix,
          3,
          scratchComputedTranslation$2
        );
        if (!Cartesian4.equals(translation, Cartesian4.UNIT_W)) {
          Transforms.basisTo2D(projection, modelMatrix, modelMatrix);
        }
      }

      var boundingSphere = this._drawCommand.boundingVolume;
      BoundingSphere.clone(this._boundingSphere, boundingSphere);

      if (this._cull) {
        var center = boundingSphere.center;
        Matrix4.multiplyByPoint(modelMatrix, center, center);
        var scale = Matrix4.getScale(modelMatrix, scratchScale$5);
        boundingSphere.radius *= Cartesian3.maximumComponent(scale);
      }
    }

    if (this.clippingPlanesDirty) {
      this.clippingPlanesDirty = false;
      shadersDirty = true;
    }

    if (this._attenuation !== this.attenuation) {
      this._attenuation = this.attenuation;
      shadersDirty = true;
    }

    if (this.backFaceCulling !== this._backFaceCulling) {
      this._backFaceCulling = this.backFaceCulling;
      shadersDirty = true;
    }

    if (this.normalShading !== this._normalShading) {
      this._normalShading = this.normalShading;
      shadersDirty = true;
    }

    if (this._style !== this.style || this.styleDirty) {
      this._style = this.style;
      this.styleDirty = false;
      shadersDirty = true;
    }

    if (shadersDirty) {
      createShaders$1(this, frameState, this._style);
    }

    this._drawCommand.castShadows = ShadowMode$1.castShadows(this.shadows);
    this._drawCommand.receiveShadows = ShadowMode$1.receiveShadows(this.shadows);

    // Update the render state
    var isTranslucent =
      this._highlightColor.alpha < 1.0 ||
      this._constantColor.alpha < 1.0 ||
      this._styleTranslucent;
    this._drawCommand.renderState = isTranslucent
      ? this._translucentRenderState
      : this._opaqueRenderState;
    this._drawCommand.pass = isTranslucent ? Pass$1.TRANSLUCENT : this._opaquePass;

    var commandList = frameState.commandList;

    var passes = frameState.passes;
    if (passes.render || passes.pick) {
      commandList.push(this._drawCommand);
    }
  };

  PointCloud.prototype.isDestroyed = function () {
    return false;
  };

  PointCloud.prototype.destroy = function () {
    var command = this._drawCommand;
    if (defined(command)) {
      command.vertexArray = command.vertexArray && command.vertexArray.destroy();
      command.shaderProgram =
        command.shaderProgram && command.shaderProgram.destroy();
    }
    return destroyObject(this);
  };

  function attachTexture(framebuffer, attachment, texture) {
    var gl = framebuffer._gl;
    gl.framebufferTexture2D(
      gl.FRAMEBUFFER,
      attachment,
      texture._target,
      texture._texture,
      0
    );
  }

  function attachRenderbuffer(framebuffer, attachment, renderbuffer) {
    var gl = framebuffer._gl;
    gl.framebufferRenderbuffer(
      gl.FRAMEBUFFER,
      attachment,
      gl.RENDERBUFFER,
      renderbuffer._getRenderbuffer()
    );
  }

  /**
   * Creates a framebuffer with optional initial color, depth, and stencil attachments.
   * Framebuffers are used for render-to-texture effects; they allow us to render to
   * textures in one pass, and read from it in a later pass.
   *
   * @param {Object} options The initial framebuffer attachments as shown in the example below. <code>context</code> is required. The possible properties are <code>colorTextures</code>, <code>colorRenderbuffers</code>, <code>depthTexture</code>, <code>depthRenderbuffer</code>, <code>stencilRenderbuffer</code>, <code>depthStencilTexture</code>, and <code>depthStencilRenderbuffer</code>.
   *
   * @exception {DeveloperError} Cannot have both color texture and color renderbuffer attachments.
   * @exception {DeveloperError} Cannot have both a depth texture and depth renderbuffer attachment.
   * @exception {DeveloperError} Cannot have both a depth-stencil texture and depth-stencil renderbuffer attachment.
   * @exception {DeveloperError} Cannot have both a depth and depth-stencil renderbuffer.
   * @exception {DeveloperError} Cannot have both a stencil and depth-stencil renderbuffer.
   * @exception {DeveloperError} Cannot have both a depth and stencil renderbuffer.
   * @exception {DeveloperError} The color-texture pixel-format must be a color format.
   * @exception {DeveloperError} The depth-texture pixel-format must be DEPTH_COMPONENT.
   * @exception {DeveloperError} The depth-stencil-texture pixel-format must be DEPTH_STENCIL.
   * @exception {DeveloperError} The number of color attachments exceeds the number supported.
   * @exception {DeveloperError} The color-texture pixel datatype is HALF_FLOAT and the WebGL implementation does not support the EXT_color_buffer_half_float extension.
   * @exception {DeveloperError} The color-texture pixel datatype is FLOAT and the WebGL implementation does not support the EXT_color_buffer_float or WEBGL_color_buffer_float extensions.
   *
   * @example
   * // Create a framebuffer with color and depth texture attachments.
   * var width = context.canvas.clientWidth;
   * var height = context.canvas.clientHeight;
   * var framebuffer = new Framebuffer({
   *   context : context,
   *   colorTextures : [new Texture({
   *     context : context,
   *     width : width,
   *     height : height,
   *     pixelFormat : PixelFormat.RGBA
   *   })],
   *   depthTexture : new Texture({
   *     context : context,
   *     width : width,
   *     height : height,
   *     pixelFormat : PixelFormat.DEPTH_COMPONENT,
   *     pixelDatatype : PixelDatatype.UNSIGNED_SHORT
   *   })
   * });
   *
   * @private
   * @constructor
   */
  function Framebuffer(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var context = options.context;
    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", context);
    //>>includeEnd('debug');

    var gl = context._gl;
    var maximumColorAttachments = ContextLimits.maximumColorAttachments;

    this._gl = gl;
    this._framebuffer = gl.createFramebuffer();

    this._colorTextures = [];
    this._colorRenderbuffers = [];
    this._activeColorAttachments = [];

    this._depthTexture = undefined;
    this._depthRenderbuffer = undefined;
    this._stencilRenderbuffer = undefined;
    this._depthStencilTexture = undefined;
    this._depthStencilRenderbuffer = undefined;

    /**
     * When true, the framebuffer owns its attachments so they will be destroyed when
     * {@link Framebuffer#destroy} is called or when a new attachment is assigned
     * to an attachment point.
     *
     * @type {Boolean}
     * @default true
     *
     * @see Framebuffer#destroy
     */
    this.destroyAttachments = defaultValue(options.destroyAttachments, true);

    // Throw if a texture and renderbuffer are attached to the same point.  This won't
    // cause a WebGL error (because only one will be attached), but is likely a developer error.

    //>>includeStart('debug', pragmas.debug);
    if (defined(options.colorTextures) && defined(options.colorRenderbuffers)) {
      throw new DeveloperError(
        "Cannot have both color texture and color renderbuffer attachments."
      );
    }
    if (defined(options.depthTexture) && defined(options.depthRenderbuffer)) {
      throw new DeveloperError(
        "Cannot have both a depth texture and depth renderbuffer attachment."
      );
    }
    if (
      defined(options.depthStencilTexture) &&
      defined(options.depthStencilRenderbuffer)
    ) {
      throw new DeveloperError(
        "Cannot have both a depth-stencil texture and depth-stencil renderbuffer attachment."
      );
    }
    //>>includeEnd('debug');

    // Avoid errors defined in Section 6.5 of the WebGL spec
    var depthAttachment =
      defined(options.depthTexture) || defined(options.depthRenderbuffer);
    var depthStencilAttachment =
      defined(options.depthStencilTexture) ||
      defined(options.depthStencilRenderbuffer);

    //>>includeStart('debug', pragmas.debug);
    if (depthAttachment && depthStencilAttachment) {
      throw new DeveloperError(
        "Cannot have both a depth and depth-stencil attachment."
      );
    }
    if (defined(options.stencilRenderbuffer) && depthStencilAttachment) {
      throw new DeveloperError(
        "Cannot have both a stencil and depth-stencil attachment."
      );
    }
    if (depthAttachment && defined(options.stencilRenderbuffer)) {
      throw new DeveloperError(
        "Cannot have both a depth and stencil attachment."
      );
    }
    //>>includeEnd('debug');

    ///////////////////////////////////////////////////////////////////

    this._bind();

    var texture;
    var renderbuffer;
    var i;
    var length;
    var attachmentEnum;

    if (defined(options.colorTextures)) {
      var textures = options.colorTextures;
      length = this._colorTextures.length = this._activeColorAttachments.length =
        textures.length;

      //>>includeStart('debug', pragmas.debug);
      if (length > maximumColorAttachments) {
        throw new DeveloperError(
          "The number of color attachments exceeds the number supported."
        );
      }
      //>>includeEnd('debug');

      for (i = 0; i < length; ++i) {
        texture = textures[i];

        //>>includeStart('debug', pragmas.debug);
        if (!PixelFormat$1.isColorFormat(texture.pixelFormat)) {
          throw new DeveloperError(
            "The color-texture pixel-format must be a color format."
          );
        }
        if (
          texture.pixelDatatype === PixelDatatype$1.FLOAT &&
          !context.colorBufferFloat
        ) {
          throw new DeveloperError(
            "The color texture pixel datatype is FLOAT and the WebGL implementation does not support the EXT_color_buffer_float or WEBGL_color_buffer_float extensions. See Context.colorBufferFloat."
          );
        }
        if (
          texture.pixelDatatype === PixelDatatype$1.HALF_FLOAT &&
          !context.colorBufferHalfFloat
        ) {
          throw new DeveloperError(
            "The color texture pixel datatype is HALF_FLOAT and the WebGL implementation does not support the EXT_color_buffer_half_float extension. See Context.colorBufferHalfFloat."
          );
        }
        //>>includeEnd('debug');

        attachmentEnum = this._gl.COLOR_ATTACHMENT0 + i;
        attachTexture(this, attachmentEnum, texture);
        this._activeColorAttachments[i] = attachmentEnum;
        this._colorTextures[i] = texture;
      }
    }

    if (defined(options.colorRenderbuffers)) {
      var renderbuffers = options.colorRenderbuffers;
      length = this._colorRenderbuffers.length = this._activeColorAttachments.length =
        renderbuffers.length;

      //>>includeStart('debug', pragmas.debug);
      if (length > maximumColorAttachments) {
        throw new DeveloperError(
          "The number of color attachments exceeds the number supported."
        );
      }
      //>>includeEnd('debug');

      for (i = 0; i < length; ++i) {
        renderbuffer = renderbuffers[i];
        attachmentEnum = this._gl.COLOR_ATTACHMENT0 + i;
        attachRenderbuffer(this, attachmentEnum, renderbuffer);
        this._activeColorAttachments[i] = attachmentEnum;
        this._colorRenderbuffers[i] = renderbuffer;
      }
    }

    if (defined(options.depthTexture)) {
      texture = options.depthTexture;

      //>>includeStart('debug', pragmas.debug);
      if (texture.pixelFormat !== PixelFormat$1.DEPTH_COMPONENT) {
        throw new DeveloperError(
          "The depth-texture pixel-format must be DEPTH_COMPONENT."
        );
      }
      //>>includeEnd('debug');

      attachTexture(this, this._gl.DEPTH_ATTACHMENT, texture);
      this._depthTexture = texture;
    }

    if (defined(options.depthRenderbuffer)) {
      renderbuffer = options.depthRenderbuffer;
      attachRenderbuffer(this, this._gl.DEPTH_ATTACHMENT, renderbuffer);
      this._depthRenderbuffer = renderbuffer;
    }

    if (defined(options.stencilRenderbuffer)) {
      renderbuffer = options.stencilRenderbuffer;
      attachRenderbuffer(this, this._gl.STENCIL_ATTACHMENT, renderbuffer);
      this._stencilRenderbuffer = renderbuffer;
    }

    if (defined(options.depthStencilTexture)) {
      texture = options.depthStencilTexture;

      //>>includeStart('debug', pragmas.debug);
      if (texture.pixelFormat !== PixelFormat$1.DEPTH_STENCIL) {
        throw new DeveloperError(
          "The depth-stencil pixel-format must be DEPTH_STENCIL."
        );
      }
      //>>includeEnd('debug');

      attachTexture(this, this._gl.DEPTH_STENCIL_ATTACHMENT, texture);
      this._depthStencilTexture = texture;
    }

    if (defined(options.depthStencilRenderbuffer)) {
      renderbuffer = options.depthStencilRenderbuffer;
      attachRenderbuffer(this, this._gl.DEPTH_STENCIL_ATTACHMENT, renderbuffer);
      this._depthStencilRenderbuffer = renderbuffer;
    }

    this._unBind();
  }

  Object.defineProperties(Framebuffer.prototype, {
    /**
     * The status of the framebuffer. If the status is not WebGLConstants.FRAMEBUFFER_COMPLETE,
     * a {@link DeveloperError} will be thrown when attempting to render to the framebuffer.
     * @memberof Framebuffer.prototype
     * @type {Number}
     */
    status: {
      get: function () {
        this._bind();
        var status = this._gl.checkFramebufferStatus(this._gl.FRAMEBUFFER);
        this._unBind();
        return status;
      },
    },
    numberOfColorAttachments: {
      get: function () {
        return this._activeColorAttachments.length;
      },
    },
    depthTexture: {
      get: function () {
        return this._depthTexture;
      },
    },
    depthRenderbuffer: {
      get: function () {
        return this._depthRenderbuffer;
      },
    },
    stencilRenderbuffer: {
      get: function () {
        return this._stencilRenderbuffer;
      },
    },
    depthStencilTexture: {
      get: function () {
        return this._depthStencilTexture;
      },
    },
    depthStencilRenderbuffer: {
      get: function () {
        return this._depthStencilRenderbuffer;
      },
    },

    /**
     * True if the framebuffer has a depth attachment.  Depth attachments include
     * depth and depth-stencil textures, and depth and depth-stencil renderbuffers.  When
     * rendering to a framebuffer, a depth attachment is required for the depth test to have effect.
     * @memberof Framebuffer.prototype
     * @type {Boolean}
     */
    hasDepthAttachment: {
      get: function () {
        return !!(
          this.depthTexture ||
          this.depthRenderbuffer ||
          this.depthStencilTexture ||
          this.depthStencilRenderbuffer
        );
      },
    },
  });

  Framebuffer.prototype._bind = function () {
    var gl = this._gl;
    gl.bindFramebuffer(gl.FRAMEBUFFER, this._framebuffer);
  };

  Framebuffer.prototype._unBind = function () {
    var gl = this._gl;
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);
  };

  Framebuffer.prototype._getActiveColorAttachments = function () {
    return this._activeColorAttachments;
  };

  Framebuffer.prototype.getColorTexture = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index) || index < 0 || index >= this._colorTextures.length) {
      throw new DeveloperError(
        "index is required, must be greater than or equal to zero and must be less than the number of color attachments."
      );
    }
    //>>includeEnd('debug');

    return this._colorTextures[index];
  };

  Framebuffer.prototype.getColorRenderbuffer = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(index) ||
      index < 0 ||
      index >= this._colorRenderbuffers.length
    ) {
      throw new DeveloperError(
        "index is required, must be greater than or equal to zero and must be less than the number of color attachments."
      );
    }
    //>>includeEnd('debug');

    return this._colorRenderbuffers[index];
  };

  Framebuffer.prototype.isDestroyed = function () {
    return false;
  };

  Framebuffer.prototype.destroy = function () {
    if (this.destroyAttachments) {
      // If the color texture is a cube map face, it is owned by the cube map, and will not be destroyed.
      var i = 0;
      var textures = this._colorTextures;
      var length = textures.length;
      for (; i < length; ++i) {
        var texture = textures[i];
        if (defined(texture)) {
          texture.destroy();
        }
      }

      var renderbuffers = this._colorRenderbuffers;
      length = renderbuffers.length;
      for (i = 0; i < length; ++i) {
        var renderbuffer = renderbuffers[i];
        if (defined(renderbuffer)) {
          renderbuffer.destroy();
        }
      }

      this._depthTexture = this._depthTexture && this._depthTexture.destroy();
      this._depthRenderbuffer =
        this._depthRenderbuffer && this._depthRenderbuffer.destroy();
      this._stencilRenderbuffer =
        this._stencilRenderbuffer && this._stencilRenderbuffer.destroy();
      this._depthStencilTexture =
        this._depthStencilTexture && this._depthStencilTexture.destroy();
      this._depthStencilRenderbuffer =
        this._depthStencilRenderbuffer &&
        this._depthStencilRenderbuffer.destroy();
    }

    this._gl.deleteFramebuffer(this._framebuffer);
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var PointCloudEyeDomeLightingShader = "#extension GL_EXT_frag_depth : enable\n\
uniform sampler2D u_pointCloud_colorGBuffer;\n\
uniform sampler2D u_pointCloud_depthGBuffer;\n\
uniform vec2 u_distanceAndEdlStrength;\n\
varying vec2 v_textureCoordinates;\n\
vec2 neighborContribution(float log2Depth, vec2 offset)\n\
{\n\
float dist = u_distanceAndEdlStrength.x;\n\
vec2 texCoordOrig = v_textureCoordinates + offset * dist;\n\
vec2 texCoord0 = v_textureCoordinates + offset * floor(dist);\n\
vec2 texCoord1 = v_textureCoordinates + offset * ceil(dist);\n\
float depthOrLogDepth0 = czm_unpackDepth(texture2D(u_pointCloud_depthGBuffer, texCoord0));\n\
float depthOrLogDepth1 = czm_unpackDepth(texture2D(u_pointCloud_depthGBuffer, texCoord1));\n\
if (depthOrLogDepth0 == 0.0 || depthOrLogDepth1 == 0.0) {\n\
return vec2(0.0);\n\
}\n\
float depthMix = mix(depthOrLogDepth0, depthOrLogDepth1, fract(dist));\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(texCoordOrig, depthMix);\n\
return vec2(max(0.0, log2Depth - log2(-eyeCoordinate.z / eyeCoordinate.w)), 1.0);\n\
}\n\
void main()\n\
{\n\
float depthOrLogDepth = czm_unpackDepth(texture2D(u_pointCloud_depthGBuffer, v_textureCoordinates));\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(gl_FragCoord.xy, depthOrLogDepth);\n\
eyeCoordinate /= eyeCoordinate.w;\n\
float log2Depth = log2(-eyeCoordinate.z);\n\
if (depthOrLogDepth == 0.0)\n\
{\n\
discard;\n\
}\n\
vec4 color = texture2D(u_pointCloud_colorGBuffer, v_textureCoordinates);\n\
vec2 texelSize = 1.0 / czm_viewport.zw;\n\
vec2 responseAndCount = vec2(0.0);\n\
responseAndCount += neighborContribution(log2Depth, vec2(-texelSize.x, 0.0));\n\
responseAndCount += neighborContribution(log2Depth, vec2(+texelSize.x, 0.0));\n\
responseAndCount += neighborContribution(log2Depth, vec2(0.0, -texelSize.y));\n\
responseAndCount += neighborContribution(log2Depth, vec2(0.0, +texelSize.y));\n\
float response = responseAndCount.x / responseAndCount.y;\n\
float strength = u_distanceAndEdlStrength.y;\n\
float shade = exp(-response * 300.0 * strength);\n\
color.rgb *= shade;\n\
gl_FragColor = vec4(color);\n\
gl_FragDepthEXT = depthOrLogDepth;\n\
}\n\
";

  /**
   * Eye dome lighting. Does not support points with per-point translucency, but does allow translucent styling against the globe.
   * Requires support for EXT_frag_depth and WEBGL_draw_buffers extensions in WebGL 1.0.
   *
   * @private
   */
  function PointCloudEyeDomeLighting() {
    this._framebuffer = undefined;
    this._colorGBuffer = undefined; // color gbuffer
    this._depthGBuffer = undefined; // depth gbuffer
    this._depthTexture = undefined; // needed to write depth so camera based on depth works
    this._drawCommand = undefined;
    this._clearCommand = undefined;

    this._strength = 1.0;
    this._radius = 1.0;
  }

  function destroyFramebuffer(processor) {
    var framebuffer = processor._framebuffer;
    if (!defined(framebuffer)) {
      return;
    }

    processor._colorGBuffer.destroy();
    processor._depthGBuffer.destroy();
    processor._depthTexture.destroy();
    framebuffer.destroy();

    processor._framebuffer = undefined;
    processor._colorGBuffer = undefined;
    processor._depthGBuffer = undefined;
    processor._depthTexture = undefined;
    processor._drawCommand = undefined;
    processor._clearCommand = undefined;
  }

  function createFramebuffer(processor, context) {
    var screenWidth = context.drawingBufferWidth;
    var screenHeight = context.drawingBufferHeight;

    var colorGBuffer = new Texture({
      context: context,
      width: screenWidth,
      height: screenHeight,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    var depthGBuffer = new Texture({
      context: context,
      width: screenWidth,
      height: screenHeight,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    var depthTexture = new Texture({
      context: context,
      width: screenWidth,
      height: screenHeight,
      pixelFormat: PixelFormat$1.DEPTH_COMPONENT,
      pixelDatatype: PixelDatatype$1.UNSIGNED_INT,
      sampler: Sampler.NEAREST,
    });

    processor._framebuffer = new Framebuffer({
      context: context,
      colorTextures: [colorGBuffer, depthGBuffer],
      depthTexture: depthTexture,
      destroyAttachments: false,
    });
    processor._colorGBuffer = colorGBuffer;
    processor._depthGBuffer = depthGBuffer;
    processor._depthTexture = depthTexture;
  }

  var distanceAndEdlStrengthScratch = new Cartesian2();

  function createCommands$4(processor, context) {
    var blendFS = new ShaderSource({
      defines: ["LOG_DEPTH_WRITE"],
      sources: [PointCloudEyeDomeLightingShader],
    });

    var blendUniformMap = {
      u_pointCloud_colorGBuffer: function () {
        return processor._colorGBuffer;
      },
      u_pointCloud_depthGBuffer: function () {
        return processor._depthGBuffer;
      },
      u_distanceAndEdlStrength: function () {
        distanceAndEdlStrengthScratch.x = processor._radius;
        distanceAndEdlStrengthScratch.y = processor._strength;
        return distanceAndEdlStrengthScratch;
      },
    };

    var blendRenderState = RenderState.fromCache({
      blending: BlendingState$1.ALPHA_BLEND,
      depthMask: true,
      depthTest: {
        enabled: true,
      },
      stencilTest: StencilConstants$1.setCesium3DTileBit(),
      stencilMask: StencilConstants$1.CESIUM_3D_TILE_MASK,
    });

    processor._drawCommand = context.createViewportQuadCommand(blendFS, {
      uniformMap: blendUniformMap,
      renderState: blendRenderState,
      pass: Pass$1.CESIUM_3D_TILE,
      owner: processor,
    });

    processor._clearCommand = new ClearCommand({
      framebuffer: processor._framebuffer,
      color: new Color(0.0, 0.0, 0.0, 0.0),
      depth: 1.0,
      renderState: RenderState.fromCache(),
      pass: Pass$1.CESIUM_3D_TILE,
      owner: processor,
    });
  }

  function createResources$3(processor, context) {
    var screenWidth = context.drawingBufferWidth;
    var screenHeight = context.drawingBufferHeight;
    var colorGBuffer = processor._colorGBuffer;
    var nowDirty = false;
    var resized =
      defined(colorGBuffer) &&
      (colorGBuffer.width !== screenWidth ||
        colorGBuffer.height !== screenHeight);

    if (!defined(colorGBuffer) || resized) {
      destroyFramebuffer(processor);
      createFramebuffer(processor, context);
      createCommands$4(processor, context);
      nowDirty = true;
    }
    return nowDirty;
  }

  function isSupported(context) {
    return context.drawBuffers && context.fragmentDepth;
  }

  PointCloudEyeDomeLighting.isSupported = isSupported;

  function getECShaderProgram(context, shaderProgram) {
    var shader = context.shaderCache.getDerivedShaderProgram(shaderProgram, "EC");
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;

      var fs = shaderProgram.fragmentShaderSource.clone();

      fs.sources = fs.sources.map(function (source) {
        source = ShaderSource.replaceMain(
          source,
          "czm_point_cloud_post_process_main"
        );
        source = source.replace(/gl_FragColor/g, "gl_FragData[0]");
        return source;
      });

      fs.sources.unshift("#extension GL_EXT_draw_buffers : enable \n");
      fs.sources.push(
        "void main() \n" +
          "{ \n" +
          "    czm_point_cloud_post_process_main(); \n" +
          "#ifdef LOG_DEPTH\n" +
          "    czm_writeLogDepth();\n" +
          "    gl_FragData[1] = czm_packDepth(gl_FragDepthEXT); \n" +
          "#else\n" +
          "    gl_FragData[1] = czm_packDepth(gl_FragCoord.z);\n" +
          "#endif\n" +
          "}"
      );

      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        "EC",
        {
          vertexShaderSource: shaderProgram.vertexShaderSource,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  PointCloudEyeDomeLighting.prototype.update = function (
    frameState,
    commandStart,
    pointCloudShading,
    boundingVolume
  ) {
    if (!isSupported(frameState.context)) {
      return;
    }

    this._strength = pointCloudShading.eyeDomeLightingStrength;
    this._radius =
      pointCloudShading.eyeDomeLightingRadius * frameState.pixelRatio;

    var dirty = createResources$3(this, frameState.context);

    // Hijack existing point commands to render into an offscreen FBO.
    var i;
    var commandList = frameState.commandList;
    var commandEnd = commandList.length;

    for (i = commandStart; i < commandEnd; ++i) {
      var command = commandList[i];
      if (
        command.primitiveType !== PrimitiveType$1.POINTS ||
        command.pass === Pass$1.TRANSLUCENT
      ) {
        continue;
      }
      var derivedCommand = command.derivedCommands.pointCloudProcessor;
      if (
        !defined(derivedCommand) ||
        command.dirty ||
        dirty ||
        derivedCommand.framebuffer !== this._framebuffer
      ) {
        // Prevent crash when tiles out-of-view come in-view during context size change
        derivedCommand = DrawCommand.shallowClone(command);
        command.derivedCommands.pointCloudProcessor = derivedCommand;

        derivedCommand.framebuffer = this._framebuffer;
        derivedCommand.shaderProgram = getECShaderProgram(
          frameState.context,
          command.shaderProgram
        );
        derivedCommand.castShadows = false;
        derivedCommand.receiveShadows = false;
      }

      commandList[i] = derivedCommand;
    }

    var clearCommand = this._clearCommand;
    var blendCommand = this._drawCommand;

    blendCommand.boundingVolume = boundingVolume;

    // Blend EDL into the main FBO
    commandList.push(blendCommand);
    commandList.push(clearCommand);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PointCloudEyeDomeLighting#destroy
   */
  PointCloudEyeDomeLighting.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * processor = processor && processor.destroy();
   *
   * @see PointCloudEyeDomeLighting#isDestroyed
   */
  PointCloudEyeDomeLighting.prototype.destroy = function () {
    destroyFramebuffer(this);
    return destroyObject(this);
  };

  /**
   * Options for performing point attenuation based on geometric error when rendering
   * point clouds using 3D Tiles.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.attenuation=false] Perform point attenuation based on geometric error.
   * @param {Number} [options.geometricErrorScale=1.0] Scale to be applied to each tile's geometric error.
   * @param {Number} [options.maximumAttenuation] Maximum attenuation in pixels. Defaults to the Cesium3DTileset's maximumScreenSpaceError.
   * @param {Number} [options.baseResolution] Average base resolution for the dataset in meters. Substitute for Geometric Error when not available.
   * @param {Boolean} [options.eyeDomeLighting=true] When true, use eye dome lighting when drawing with point attenuation.
   * @param {Number} [options.eyeDomeLightingStrength=1.0] Increasing this value increases contrast on slopes and edges.
   * @param {Number} [options.eyeDomeLightingRadius=1.0] Increase the thickness of contours from eye dome lighting.
   * @param {Boolean} [options.backFaceCulling=false] Determines whether back-facing points are hidden. This option works only if data has normals included.
   * @param {Boolean} [options.normalShading=true] Determines whether a point cloud that contains normals is shaded by the scene's light source.
   *
   * @alias PointCloudShading
   * @constructor
   */
  function PointCloudShading(options) {
    var pointCloudShading = defaultValue(options, {});

    /**
     * Perform point attenuation based on geometric error.
     * @type {Boolean}
     * @default false
     */
    this.attenuation = defaultValue(pointCloudShading.attenuation, false);

    /**
     * Scale to be applied to the geometric error before computing attenuation.
     * @type {Number}
     * @default 1.0
     */
    this.geometricErrorScale = defaultValue(
      pointCloudShading.geometricErrorScale,
      1.0
    );

    /**
     * Maximum point attenuation in pixels. If undefined, the Cesium3DTileset's maximumScreenSpaceError will be used.
     * @type {Number}
     */
    this.maximumAttenuation = pointCloudShading.maximumAttenuation;

    /**
     * Average base resolution for the dataset in meters.
     * Used in place of geometric error when geometric error is 0.
     * If undefined, an approximation will be computed for each tile that has geometric error of 0.
     * @type {Number}
     */
    this.baseResolution = pointCloudShading.baseResolution;

    /**
     * Use eye dome lighting when drawing with point attenuation
     * Requires support for EXT_frag_depth, OES_texture_float, and WEBGL_draw_buffers extensions in WebGL 1.0,
     * otherwise eye dome lighting is ignored.
     *
     * @type {Boolean}
     * @default true
     */
    this.eyeDomeLighting = defaultValue(pointCloudShading.eyeDomeLighting, true);

    /**
     * Eye dome lighting strength (apparent contrast)
     * @type {Number}
     * @default 1.0
     */
    this.eyeDomeLightingStrength = defaultValue(
      pointCloudShading.eyeDomeLightingStrength,
      1.0
    );

    /**
     * Thickness of contours from eye dome lighting
     * @type {Number}
     * @default 1.0
     */
    this.eyeDomeLightingRadius = defaultValue(
      pointCloudShading.eyeDomeLightingRadius,
      1.0
    );

    /**
     * Determines whether back-facing points are hidden.
     * This option works only if data has normals included.
     *
     * @type {Boolean}
     * @default false
     */
    this.backFaceCulling = defaultValue(pointCloudShading.backFaceCulling, false);

    /**
     * Determines whether a point cloud that contains normals is shaded by the scene's light source.
     *
     * @type {Boolean}
     * @default true
     */
    this.normalShading = defaultValue(pointCloudShading.normalShading, true);
  }

  /**
   * Determines if point cloud shading is supported.
   *
   * @param {Scene} scene The scene.
   * @returns {Boolean} <code>true</code> if point cloud shading is supported; otherwise, returns <code>false</code>
   */
  PointCloudShading.isSupported = function (scene) {
    return PointCloudEyeDomeLighting.isSupported(scene.context);
  };

  /**
   * Represents the contents of a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/PointCloud|Point Cloud}
   * tile in a {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias PointCloud3DTileContent
   * @constructor
   *
   * @private
   */
  function PointCloud3DTileContent(
    tileset,
    tile,
    resource,
    arrayBuffer,
    byteOffset
  ) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;
    this._pickId = undefined; // Only defined when batchTable is undefined
    this._batchTable = undefined; // Used when feature table contains BATCH_ID semantic
    this._styleDirty = false;
    this._features = undefined;
    this.featurePropertiesDirty = false;

    this._pointCloud = new PointCloud({
      arrayBuffer: arrayBuffer,
      byteOffset: byteOffset,
      cull: false,
      opaquePass: Pass$1.CESIUM_3D_TILE,
      vertexShaderLoaded: getVertexShaderLoaded(this),
      fragmentShaderLoaded: getFragmentShaderLoaded(this),
      uniformMapLoaded: getUniformMapLoaded(this),
      batchTableLoaded: getBatchTableLoaded(this),
      pickIdLoaded: getPickIdLoaded(this),
    });
  }

  Object.defineProperties(PointCloud3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        if (defined(this._batchTable)) {
          return this._batchTable.featuresLength;
        }
        return 0;
      },
    },

    pointsLength: {
      get: function () {
        return this._pointCloud.pointsLength;
      },
    },

    trianglesLength: {
      get: function () {
        return 0;
      },
    },

    geometryByteLength: {
      get: function () {
        return this._pointCloud.geometryByteLength;
      },
    },

    texturesByteLength: {
      get: function () {
        return 0;
      },
    },

    batchTableByteLength: {
      get: function () {
        if (defined(this._batchTable)) {
          return this._batchTable.memorySizeInBytes;
        }
        return 0;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return this._pointCloud.readyPromise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    batchTable: {
      get: function () {
        return this._batchTable;
      },
    },
  });

  function getVertexShaderLoaded(content) {
    return function (vs) {
      if (defined(content._batchTable)) {
        return content._batchTable.getVertexShaderCallback(
          false,
          "a_batchId",
          undefined
        )(vs);
      }
      return vs;
    };
  }

  function getFragmentShaderLoaded(content) {
    return function (fs) {
      if (defined(content._batchTable)) {
        return content._batchTable.getFragmentShaderCallback(
          false,
          undefined
        )(fs);
      }
      return "uniform vec4 czm_pickColor;\n" + fs;
    };
  }

  function getUniformMapLoaded(content) {
    return function (uniformMap) {
      if (defined(content._batchTable)) {
        return content._batchTable.getUniformMapCallback()(uniformMap);
      }
      return combine(uniformMap, {
        czm_pickColor: function () {
          return content._pickId.color;
        },
      });
    };
  }

  function getBatchTableLoaded(content) {
    return function (batchLength, batchTableJson, batchTableBinary) {
      content._batchTable = new Cesium3DTileBatchTable(
        content,
        batchLength,
        batchTableJson,
        batchTableBinary
      );
    };
  }

  function getPickIdLoaded(content) {
    return function () {
      return defined(content._batchTable)
        ? content._batchTable.getPickId()
        : "czm_pickColor";
    };
  }

  function getGeometricError(content) {
    var pointCloudShading = content._tileset.pointCloudShading;
    var sphereVolume = content._tile.contentBoundingVolume.boundingSphere.volume();
    var baseResolutionApproximation = CesiumMath.cbrt(
      sphereVolume / content.pointsLength
    );

    var geometricError = content._tile.geometricError;
    if (geometricError === 0) {
      if (
        defined(pointCloudShading) &&
        defined(pointCloudShading.baseResolution)
      ) {
        geometricError = pointCloudShading.baseResolution;
      } else {
        geometricError = baseResolutionApproximation;
      }
    }
    return geometricError;
  }

  function createFeatures$3(content) {
    var featuresLength = content.featuresLength;
    if (!defined(content._features) && featuresLength > 0) {
      var features = new Array(featuresLength);
      for (var i = 0; i < featuresLength; ++i) {
        features[i] = new Cesium3DTileFeature(content, i);
      }
      content._features = features;
    }
  }

  PointCloud3DTileContent.prototype.hasProperty = function (batchId, name) {
    if (defined(this._batchTable)) {
      return this._batchTable.hasProperty(batchId, name);
    }
    return false;
  };

  /**
   * Part of the {@link Cesium3DTileContent} interface.
   *
   * In this context a feature refers to a group of points that share the same BATCH_ID.
   * For example all the points that represent a door in a house point cloud would be a feature.
   *
   * Features are backed by a batch table and can be colored, shown/hidden, picked, etc like features
   * in b3dm and i3dm.
   *
   * When the BATCH_ID semantic is omitted and the point cloud stores per-point properties, they
   * are not accessible by getFeature. They are only used for dynamic styling.
   */
  PointCloud3DTileContent.prototype.getFeature = function (batchId) {
    if (!defined(this._batchTable)) {
      return undefined;
    }
    var featuresLength = this.featuresLength;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(batchId) || batchId < 0 || batchId >= featuresLength) {
      throw new DeveloperError(
        "batchId is required and between zero and featuresLength - 1 (" +
          (featuresLength - 1) +
          ")."
      );
    }
    //>>includeEnd('debug');
    createFeatures$3(this);
    return this._features[batchId];
  };

  PointCloud3DTileContent.prototype.applyDebugSettings = function (
    enabled,
    color
  ) {
    this._pointCloud.color = enabled ? color : Color.WHITE;
  };

  PointCloud3DTileContent.prototype.applyStyle = function (style) {
    if (defined(this._batchTable)) {
      this._batchTable.applyStyle(style);
    } else {
      this._styleDirty = true;
    }
  };

  var defaultShading = new PointCloudShading();

  PointCloud3DTileContent.prototype.update = function (tileset, frameState) {
    var pointCloud = this._pointCloud;
    var pointCloudShading = defaultValue(
      tileset.pointCloudShading,
      defaultShading
    );
    var tile = this._tile;
    var batchTable = this._batchTable;
    var mode = frameState.mode;
    var clippingPlanes = tileset.clippingPlanes;

    if (!defined(this._pickId) && !defined(batchTable)) {
      this._pickId = frameState.context.createPickId({
        primitive: tileset,
        content: this,
      });
    }

    if (defined(batchTable)) {
      batchTable.update(tileset, frameState);
    }

    var boundingSphere;
    if (defined(tile._contentBoundingVolume)) {
      boundingSphere =
        mode === SceneMode$1.SCENE3D
          ? tile._contentBoundingVolume.boundingSphere
          : tile._contentBoundingVolume2D.boundingSphere;
    } else {
      boundingSphere =
        mode === SceneMode$1.SCENE3D
          ? tile._boundingVolume.boundingSphere
          : tile._boundingVolume2D.boundingSphere;
    }

    var styleDirty = this._styleDirty;
    this._styleDirty = false;

    pointCloud.clippingPlanesOriginMatrix = tileset.clippingPlanesOriginMatrix;
    pointCloud.style = defined(batchTable) ? undefined : tileset.style;
    pointCloud.styleDirty = styleDirty;
    pointCloud.modelMatrix = tile.computedTransform;
    pointCloud.time = tileset.timeSinceLoad;
    pointCloud.shadows = tileset.shadows;
    pointCloud.boundingSphere = boundingSphere;
    pointCloud.clippingPlanes = clippingPlanes;
    pointCloud.isClipped =
      defined(clippingPlanes) && clippingPlanes.enabled && tile._isClipped;
    pointCloud.clippingPlanesDirty = tile.clippingPlanesDirty;
    pointCloud.attenuation = pointCloudShading.attenuation;
    pointCloud.backFaceCulling = pointCloudShading.backFaceCulling;
    pointCloud.normalShading = pointCloudShading.normalShading;
    pointCloud.geometricError = getGeometricError(this);
    pointCloud.geometricErrorScale = pointCloudShading.geometricErrorScale;
    if (
      defined(pointCloudShading) &&
      defined(pointCloudShading.maximumAttenuation)
    ) {
      pointCloud.maximumAttenuation = pointCloudShading.maximumAttenuation;
    } else if (tile.refine === Cesium3DTileRefine$1.ADD) {
      pointCloud.maximumAttenuation = 5.0;
    } else {
      pointCloud.maximumAttenuation = tileset.maximumScreenSpaceError;
    }

    pointCloud.update(frameState);
  };

  PointCloud3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  PointCloud3DTileContent.prototype.destroy = function () {
    this._pickId = this._pickId && this._pickId.destroy();
    this._pointCloud = this._pointCloud && this._pointCloud.destroy();
    this._batchTable = this._batchTable && this._batchTable.destroy();
    return destroyObject(this);
  };

  /**
   * Represents content for a tile in a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset whose
   * content points to another 3D Tiles tileset.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Tileset3DTileContent
   * @constructor
   *
   * @private
   */
  function Tileset3DTileContent(
    tileset,
    tile,
    resource,
    arrayBuffer,
    byteOffset
  ) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;
    this._readyPromise = when.defer();

    this.featurePropertiesDirty = false;

    initialize$7(this, arrayBuffer, byteOffset);
  }

  Object.defineProperties(Tileset3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        return 0;
      },
    },

    pointsLength: {
      get: function () {
        return 0;
      },
    },

    trianglesLength: {
      get: function () {
        return 0;
      },
    },

    geometryByteLength: {
      get: function () {
        return 0;
      },
    },

    texturesByteLength: {
      get: function () {
        return 0;
      },
    },

    batchTableByteLength: {
      get: function () {
        return 0;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    batchTable: {
      get: function () {
        return undefined;
      },
    },
  });

  function initialize$7(content, arrayBuffer, byteOffset) {
    byteOffset = defaultValue(byteOffset, 0);
    var uint8Array = new Uint8Array(arrayBuffer);
    var jsonString = getStringFromTypedArray(uint8Array, byteOffset);
    var tilesetJson;

    try {
      tilesetJson = JSON.parse(jsonString);
    } catch (error) {
      content._readyPromise.reject(new RuntimeError("Invalid tile content."));
      return;
    }

    content._tileset.loadTileset(content._resource, tilesetJson, content._tile);
    content._readyPromise.resolve(content);
  }

  /**
   * Part of the {@link Cesium3DTileContent} interface.  <code>Tileset3DTileContent</code>
   * always returns <code>false</code> since a tile of this type does not have any features.
   */
  Tileset3DTileContent.prototype.hasProperty = function (batchId, name) {
    return false;
  };

  /**
   * Part of the {@link Cesium3DTileContent} interface.  <code>Tileset3DTileContent</code>
   * always returns <code>undefined</code> since a tile of this type does not have any features.
   */
  Tileset3DTileContent.prototype.getFeature = function (batchId) {
    return undefined;
  };

  Tileset3DTileContent.prototype.applyDebugSettings = function (
    enabled,
    color
  ) {};

  Tileset3DTileContent.prototype.applyStyle = function (style) {};

  Tileset3DTileContent.prototype.update = function (tileset, frameState) {};

  Tileset3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Tileset3DTileContent.prototype.destroy = function () {
    return destroyObject(this);
  };

  /**
   * @private
   */
  function VertexArrayFacade(context, attributes, sizeInVertices, instanced) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("context", context);
    if (!attributes || attributes.length === 0) {
      throw new DeveloperError("At least one attribute is required.");
    }
    //>>includeEnd('debug');

    var attrs = VertexArrayFacade._verifyAttributes(attributes);
    sizeInVertices = defaultValue(sizeInVertices, 0);
    var precreatedAttributes = [];
    var attributesByUsage = {};
    var attributesForUsage;
    var usage;

    // Bucket the attributes by usage.
    var length = attrs.length;
    for (var i = 0; i < length; ++i) {
      var attribute = attrs[i];

      // If the attribute already has a vertex buffer, we do not need
      // to manage a vertex buffer or typed array for it.
      if (attribute.vertexBuffer) {
        precreatedAttributes.push(attribute);
        continue;
      }

      usage = attribute.usage;
      attributesForUsage = attributesByUsage[usage];
      if (!defined(attributesForUsage)) {
        attributesForUsage = attributesByUsage[usage] = [];
      }

      attributesForUsage.push(attribute);
    }

    // A function to sort attributes by the size of their components.  From left to right, a vertex
    // stores floats, shorts, and then bytes.
    function compare(left, right) {
      return (
        ComponentDatatype$1.getSizeInBytes(right.componentDatatype) -
        ComponentDatatype$1.getSizeInBytes(left.componentDatatype)
      );
    }

    this._allBuffers = [];

    for (usage in attributesByUsage) {
      if (attributesByUsage.hasOwnProperty(usage)) {
        attributesForUsage = attributesByUsage[usage];

        attributesForUsage.sort(compare);
        var vertexSizeInBytes = VertexArrayFacade._vertexSizeInBytes(
          attributesForUsage
        );

        var bufferUsage = attributesForUsage[0].usage;

        var buffer = {
          vertexSizeInBytes: vertexSizeInBytes,
          vertexBuffer: undefined,
          usage: bufferUsage,
          needsCommit: false,
          arrayBuffer: undefined,
          arrayViews: VertexArrayFacade._createArrayViews(
            attributesForUsage,
            vertexSizeInBytes
          ),
        };

        this._allBuffers.push(buffer);
      }
    }

    this._size = 0;
    this._instanced = defaultValue(instanced, false);

    this._precreated = precreatedAttributes;
    this._context = context;

    this.writers = undefined;
    this.va = undefined;

    this.resize(sizeInVertices);
  }
  VertexArrayFacade._verifyAttributes = function (attributes) {
    var attrs = [];

    for (var i = 0; i < attributes.length; ++i) {
      var attribute = attributes[i];

      var attr = {
        index: defaultValue(attribute.index, i),
        enabled: defaultValue(attribute.enabled, true),
        componentsPerAttribute: attribute.componentsPerAttribute,
        componentDatatype: defaultValue(
          attribute.componentDatatype,
          ComponentDatatype$1.FLOAT
        ),
        normalize: defaultValue(attribute.normalize, false),

        // There will be either a vertexBuffer or an [optional] usage.
        vertexBuffer: attribute.vertexBuffer,
        usage: defaultValue(attribute.usage, BufferUsage$1.STATIC_DRAW),
      };
      attrs.push(attr);

      //>>includeStart('debug', pragmas.debug);
      if (
        attr.componentsPerAttribute !== 1 &&
        attr.componentsPerAttribute !== 2 &&
        attr.componentsPerAttribute !== 3 &&
        attr.componentsPerAttribute !== 4
      ) {
        throw new DeveloperError(
          "attribute.componentsPerAttribute must be in the range [1, 4]."
        );
      }

      var datatype = attr.componentDatatype;
      if (!ComponentDatatype$1.validate(datatype)) {
        throw new DeveloperError(
          "Attribute must have a valid componentDatatype or not specify it."
        );
      }

      if (!BufferUsage$1.validate(attr.usage)) {
        throw new DeveloperError(
          "Attribute must have a valid usage or not specify it."
        );
      }
      //>>includeEnd('debug');
    }

    // Verify all attribute names are unique.
    var uniqueIndices = new Array(attrs.length);
    for (var j = 0; j < attrs.length; ++j) {
      var currentAttr = attrs[j];
      var index = currentAttr.index;
      //>>includeStart('debug', pragmas.debug);
      if (uniqueIndices[index]) {
        throw new DeveloperError(
          "Index " + index + " is used by more than one attribute."
        );
      }
      //>>includeEnd('debug');
      uniqueIndices[index] = true;
    }

    return attrs;
  };

  VertexArrayFacade._vertexSizeInBytes = function (attributes) {
    var sizeInBytes = 0;

    var length = attributes.length;
    for (var i = 0; i < length; ++i) {
      var attribute = attributes[i];
      sizeInBytes +=
        attribute.componentsPerAttribute *
        ComponentDatatype$1.getSizeInBytes(attribute.componentDatatype);
    }

    var maxComponentSizeInBytes =
      length > 0
        ? ComponentDatatype$1.getSizeInBytes(attributes[0].componentDatatype)
        : 0; // Sorted by size
    var remainder =
      maxComponentSizeInBytes > 0 ? sizeInBytes % maxComponentSizeInBytes : 0;
    var padding = remainder === 0 ? 0 : maxComponentSizeInBytes - remainder;
    sizeInBytes += padding;

    return sizeInBytes;
  };

  VertexArrayFacade._createArrayViews = function (attributes, vertexSizeInBytes) {
    var views = [];
    var offsetInBytes = 0;

    var length = attributes.length;
    for (var i = 0; i < length; ++i) {
      var attribute = attributes[i];
      var componentDatatype = attribute.componentDatatype;

      views.push({
        index: attribute.index,
        enabled: attribute.enabled,
        componentsPerAttribute: attribute.componentsPerAttribute,
        componentDatatype: componentDatatype,
        normalize: attribute.normalize,

        offsetInBytes: offsetInBytes,
        vertexSizeInComponentType:
          vertexSizeInBytes / ComponentDatatype$1.getSizeInBytes(componentDatatype),

        view: undefined,
      });

      offsetInBytes +=
        attribute.componentsPerAttribute *
        ComponentDatatype$1.getSizeInBytes(componentDatatype);
    }

    return views;
  };

  /**
   * Invalidates writers.  Can't render again until commit is called.
   */
  VertexArrayFacade.prototype.resize = function (sizeInVertices) {
    this._size = sizeInVertices;

    var allBuffers = this._allBuffers;
    this.writers = [];

    for (var i = 0, len = allBuffers.length; i < len; ++i) {
      var buffer = allBuffers[i];

      VertexArrayFacade._resize(buffer, this._size);

      // Reserving invalidates the writers, so if client's cache them, they need to invalidate their cache.
      VertexArrayFacade._appendWriters(this.writers, buffer);
    }

    // VAs are recreated next time commit is called.
    destroyVA(this);
  };

  VertexArrayFacade._resize = function (buffer, size) {
    if (buffer.vertexSizeInBytes > 0) {
      // Create larger array buffer
      var arrayBuffer = new ArrayBuffer(size * buffer.vertexSizeInBytes);

      // Copy contents from previous array buffer
      if (defined(buffer.arrayBuffer)) {
        var destView = new Uint8Array(arrayBuffer);
        var sourceView = new Uint8Array(buffer.arrayBuffer);
        var sourceLength = sourceView.length;
        for (var j = 0; j < sourceLength; ++j) {
          destView[j] = sourceView[j];
        }
      }

      // Create typed views into the new array buffer
      var views = buffer.arrayViews;
      var length = views.length;
      for (var i = 0; i < length; ++i) {
        var view = views[i];
        view.view = ComponentDatatype$1.createArrayBufferView(
          view.componentDatatype,
          arrayBuffer,
          view.offsetInBytes
        );
      }

      buffer.arrayBuffer = arrayBuffer;
    }
  };

  var createWriters = [
    // 1 component per attribute
    function (buffer, view, vertexSizeInComponentType) {
      return function (index, attribute) {
        view[index * vertexSizeInComponentType] = attribute;
        buffer.needsCommit = true;
      };
    },

    // 2 component per attribute
    function (buffer, view, vertexSizeInComponentType) {
      return function (index, component0, component1) {
        var i = index * vertexSizeInComponentType;
        view[i] = component0;
        view[i + 1] = component1;
        buffer.needsCommit = true;
      };
    },

    // 3 component per attribute
    function (buffer, view, vertexSizeInComponentType) {
      return function (index, component0, component1, component2) {
        var i = index * vertexSizeInComponentType;
        view[i] = component0;
        view[i + 1] = component1;
        view[i + 2] = component2;
        buffer.needsCommit = true;
      };
    },

    // 4 component per attribute
    function (buffer, view, vertexSizeInComponentType) {
      return function (index, component0, component1, component2, component3) {
        var i = index * vertexSizeInComponentType;
        view[i] = component0;
        view[i + 1] = component1;
        view[i + 2] = component2;
        view[i + 3] = component3;
        buffer.needsCommit = true;
      };
    },
  ];

  VertexArrayFacade._appendWriters = function (writers, buffer) {
    var arrayViews = buffer.arrayViews;
    var length = arrayViews.length;
    for (var i = 0; i < length; ++i) {
      var arrayView = arrayViews[i];
      writers[arrayView.index] = createWriters[
        arrayView.componentsPerAttribute - 1
      ](buffer, arrayView.view, arrayView.vertexSizeInComponentType);
    }
  };

  VertexArrayFacade.prototype.commit = function (indexBuffer) {
    var recreateVA = false;

    var allBuffers = this._allBuffers;
    var buffer;
    var i;
    var length;

    for (i = 0, length = allBuffers.length; i < length; ++i) {
      buffer = allBuffers[i];
      recreateVA = commit(this, buffer) || recreateVA;
    }

    ///////////////////////////////////////////////////////////////////////

    if (recreateVA || !defined(this.va)) {
      destroyVA(this);
      var va = (this.va = []);

      var chunkSize = CesiumMath.SIXTY_FOUR_KILOBYTES - 4; // The 65535 index is reserved for primitive restart. Reserve the last 4 indices so that billboard quads are not broken up.
      var numberOfVertexArrays =
        defined(indexBuffer) && !this._instanced
          ? Math.ceil(this._size / chunkSize)
          : 1;
      for (var k = 0; k < numberOfVertexArrays; ++k) {
        var attributes = [];
        for (i = 0, length = allBuffers.length; i < length; ++i) {
          buffer = allBuffers[i];
          var offset = k * (buffer.vertexSizeInBytes * chunkSize);
          VertexArrayFacade._appendAttributes(
            attributes,
            buffer,
            offset,
            this._instanced
          );
        }

        attributes = attributes.concat(this._precreated);

        va.push({
          va: new VertexArray({
            context: this._context,
            attributes: attributes,
            indexBuffer: indexBuffer,
          }),
          indicesCount:
            1.5 *
            (k !== numberOfVertexArrays - 1 ? chunkSize : this._size % chunkSize),
          // TODO: not hardcode 1.5, this assumes 6 indices per 4 vertices (as for Billboard quads).
        });
      }
    }
  };

  function commit(vertexArrayFacade, buffer) {
    if (buffer.needsCommit && buffer.vertexSizeInBytes > 0) {
      buffer.needsCommit = false;

      var vertexBuffer = buffer.vertexBuffer;
      var vertexBufferSizeInBytes =
        vertexArrayFacade._size * buffer.vertexSizeInBytes;
      var vertexBufferDefined = defined(vertexBuffer);
      if (
        !vertexBufferDefined ||
        vertexBuffer.sizeInBytes < vertexBufferSizeInBytes
      ) {
        if (vertexBufferDefined) {
          vertexBuffer.destroy();
        }
        buffer.vertexBuffer = Buffer$1.createVertexBuffer({
          context: vertexArrayFacade._context,
          typedArray: buffer.arrayBuffer,
          usage: buffer.usage,
        });
        buffer.vertexBuffer.vertexArrayDestroyable = false;

        return true; // Created new vertex buffer
      }

      buffer.vertexBuffer.copyFromArrayView(buffer.arrayBuffer);
    }

    return false; // Did not create new vertex buffer
  }

  VertexArrayFacade._appendAttributes = function (
    attributes,
    buffer,
    vertexBufferOffset,
    instanced
  ) {
    var arrayViews = buffer.arrayViews;
    var length = arrayViews.length;
    for (var i = 0; i < length; ++i) {
      var view = arrayViews[i];

      attributes.push({
        index: view.index,
        enabled: view.enabled,
        componentsPerAttribute: view.componentsPerAttribute,
        componentDatatype: view.componentDatatype,
        normalize: view.normalize,
        vertexBuffer: buffer.vertexBuffer,
        offsetInBytes: vertexBufferOffset + view.offsetInBytes,
        strideInBytes: buffer.vertexSizeInBytes,
        instanceDivisor: instanced ? 1 : 0,
      });
    }
  };

  VertexArrayFacade.prototype.subCommit = function (
    offsetInVertices,
    lengthInVertices
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (offsetInVertices < 0 || offsetInVertices >= this._size) {
      throw new DeveloperError(
        "offsetInVertices must be greater than or equal to zero and less than the vertex array size."
      );
    }
    if (offsetInVertices + lengthInVertices > this._size) {
      throw new DeveloperError(
        "offsetInVertices + lengthInVertices cannot exceed the vertex array size."
      );
    }
    //>>includeEnd('debug');

    var allBuffers = this._allBuffers;
    for (var i = 0, len = allBuffers.length; i < len; ++i) {
      subCommit(allBuffers[i], offsetInVertices, lengthInVertices);
    }
  };

  function subCommit(buffer, offsetInVertices, lengthInVertices) {
    if (buffer.needsCommit && buffer.vertexSizeInBytes > 0) {
      var byteOffset = buffer.vertexSizeInBytes * offsetInVertices;
      var byteLength = buffer.vertexSizeInBytes * lengthInVertices;

      // PERFORMANCE_IDEA: If we want to get really crazy, we could consider updating
      // individual attributes instead of the entire (sub-)vertex.
      //
      // PERFORMANCE_IDEA: Does creating the typed view add too much GC overhead?
      buffer.vertexBuffer.copyFromArrayView(
        new Uint8Array(buffer.arrayBuffer, byteOffset, byteLength),
        byteOffset
      );
    }
  }

  VertexArrayFacade.prototype.endSubCommits = function () {
    var allBuffers = this._allBuffers;

    for (var i = 0, len = allBuffers.length; i < len; ++i) {
      allBuffers[i].needsCommit = false;
    }
  };

  function destroyVA(vertexArrayFacade) {
    var va = vertexArrayFacade.va;
    if (!defined(va)) {
      return;
    }

    var length = va.length;
    for (var i = 0; i < length; ++i) {
      va[i].va.destroy();
    }

    vertexArrayFacade.va = undefined;
  }

  VertexArrayFacade.prototype.isDestroyed = function () {
    return false;
  };

  VertexArrayFacade.prototype.destroy = function () {
    var allBuffers = this._allBuffers;
    for (var i = 0, len = allBuffers.length; i < len; ++i) {
      var buffer = allBuffers[i];
      buffer.vertexBuffer = buffer.vertexBuffer && buffer.vertexBuffer.destroy();
    }

    destroyVA(this);

    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var BillboardCollectionFS = "#ifdef GL_OES_standard_derivatives\n\
#extension GL_OES_standard_derivatives : enable\n\
#endif\n\
uniform sampler2D u_atlas;\n\
#ifdef VECTOR_TILE\n\
uniform vec4 u_highlightColor;\n\
#endif\n\
varying vec2 v_textureCoordinates;\n\
varying vec4 v_pickColor;\n\
varying vec4 v_color;\n\
#ifdef SDF\n\
varying vec4 v_outlineColor;\n\
varying float v_outlineWidth;\n\
#endif\n\
#ifdef FRAGMENT_DEPTH_CHECK\n\
varying vec4 v_textureCoordinateBounds;\n\
varying vec4 v_originTextureCoordinateAndTranslate;\n\
varying vec4 v_compressed;\n\
varying mat2 v_rotationMatrix;\n\
const float SHIFT_LEFT12 = 4096.0;\n\
const float SHIFT_LEFT1 = 2.0;\n\
const float SHIFT_RIGHT12 = 1.0 / 4096.0;\n\
const float SHIFT_RIGHT1 = 1.0 / 2.0;\n\
float getGlobeDepth(vec2 adjustedST, vec2 depthLookupST, bool applyTranslate, vec2 dimensions, vec2 imageSize)\n\
{\n\
vec2 lookupVector = imageSize * (depthLookupST - adjustedST);\n\
lookupVector = v_rotationMatrix * lookupVector;\n\
vec2 labelOffset = (dimensions - imageSize) * (depthLookupST - vec2(0.0, v_originTextureCoordinateAndTranslate.y));\n\
vec2 translation = v_originTextureCoordinateAndTranslate.zw;\n\
if (applyTranslate)\n\
{\n\
translation += (dimensions * v_originTextureCoordinateAndTranslate.xy * vec2(1.0, 0.0));\n\
}\n\
vec2 st = ((lookupVector - translation + labelOffset) + gl_FragCoord.xy) / czm_viewport.zw;\n\
float logDepthOrDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, st));\n\
if (logDepthOrDepth == 0.0)\n\
{\n\
return 0.0;\n\
}\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(gl_FragCoord.xy, logDepthOrDepth);\n\
return eyeCoordinate.z / eyeCoordinate.w;\n\
}\n\
#endif\n\
#ifdef SDF\n\
float getDistance(vec2 position)\n\
{\n\
return texture2D(u_atlas, position).r;\n\
}\n\
vec4 getSDFColor(vec2 position, float outlineWidth, vec4 outlineColor, float smoothing)\n\
{\n\
float distance = getDistance(position);\n\
if (outlineWidth > 0.0)\n\
{\n\
float outlineEdge = clamp(SDF_EDGE - outlineWidth, 0.0, SDF_EDGE);\n\
float outlineFactor = smoothstep(SDF_EDGE - smoothing, SDF_EDGE + smoothing, distance);\n\
vec4 sdfColor = mix(outlineColor, v_color, outlineFactor);\n\
float alpha = smoothstep(outlineEdge - smoothing, outlineEdge + smoothing, distance);\n\
return vec4(sdfColor.rgb, sdfColor.a * alpha);\n\
}\n\
else\n\
{\n\
float alpha = smoothstep(SDF_EDGE - smoothing, SDF_EDGE + smoothing, distance);\n\
return vec4(v_color.rgb, v_color.a * alpha);\n\
}\n\
}\n\
#endif\n\
void main()\n\
{\n\
vec4 color = texture2D(u_atlas, v_textureCoordinates);\n\
#ifdef SDF\n\
float outlineWidth = v_outlineWidth;\n\
vec4 outlineColor = v_outlineColor;\n\
float distance = getDistance(v_textureCoordinates);\n\
#ifdef GL_OES_standard_derivatives\n\
float smoothing = fwidth(distance);\n\
vec2 sampleOffset = 0.354 * vec2(dFdx(v_textureCoordinates) + dFdy(v_textureCoordinates));\n\
vec4 center = getSDFColor(v_textureCoordinates, outlineWidth, outlineColor, smoothing);\n\
vec4 color1 = getSDFColor(v_textureCoordinates + vec2(sampleOffset.x, sampleOffset.y), outlineWidth, outlineColor, smoothing);\n\
vec4 color2 = getSDFColor(v_textureCoordinates + vec2(-sampleOffset.x, sampleOffset.y), outlineWidth, outlineColor, smoothing);\n\
vec4 color3 = getSDFColor(v_textureCoordinates + vec2(-sampleOffset.x, -sampleOffset.y), outlineWidth, outlineColor, smoothing);\n\
vec4 color4 = getSDFColor(v_textureCoordinates + vec2(sampleOffset.x, -sampleOffset.y), outlineWidth, outlineColor, smoothing);\n\
color = (center + color1 + color2 + color3 + color4)/5.0;\n\
#else\n\
float smoothing = 1.0/32.0;\n\
color = getSDFColor(v_textureCoordinates, outlineWidth, outlineColor, smoothing);\n\
#endif\n\
color = czm_gammaCorrect(color);\n\
#else\n\
color = czm_gammaCorrect(color);\n\
color *= czm_gammaCorrect(v_color);\n\
#endif\n\
#if !defined(OPAQUE) && !defined(TRANSLUCENT)\n\
if (color.a < 0.005)\n\
{\n\
discard;\n\
}\n\
#else\n\
#ifdef OPAQUE\n\
if (color.a < 0.995)\n\
{\n\
discard;\n\
}\n\
#else\n\
if (color.a >= 0.995)\n\
{\n\
discard;\n\
}\n\
#endif\n\
#endif\n\
#ifdef VECTOR_TILE\n\
color *= u_highlightColor;\n\
#endif\n\
gl_FragColor = color;\n\
#ifdef LOG_DEPTH\n\
czm_writeLogDepth();\n\
#endif\n\
#ifdef FRAGMENT_DEPTH_CHECK\n\
float temp = v_compressed.y;\n\
temp = temp * SHIFT_RIGHT1;\n\
float temp2 = (temp - floor(temp)) * SHIFT_LEFT1;\n\
bool enableDepthTest = temp2 != 0.0;\n\
bool applyTranslate = floor(temp) != 0.0;\n\
if (enableDepthTest) {\n\
temp = v_compressed.z;\n\
temp = temp * SHIFT_RIGHT12;\n\
vec2 dimensions;\n\
dimensions.y = (temp - floor(temp)) * SHIFT_LEFT12;\n\
dimensions.x = floor(temp);\n\
temp = v_compressed.w;\n\
temp = temp * SHIFT_RIGHT12;\n\
vec2 imageSize;\n\
imageSize.y = (temp - floor(temp)) * SHIFT_LEFT12;\n\
imageSize.x = floor(temp);\n\
vec2 adjustedST = v_textureCoordinates - v_textureCoordinateBounds.xy;\n\
adjustedST = adjustedST / vec2(v_textureCoordinateBounds.z - v_textureCoordinateBounds.x, v_textureCoordinateBounds.w - v_textureCoordinateBounds.y);\n\
float epsilonEyeDepth = v_compressed.x + czm_epsilon1;\n\
float globeDepth1 = getGlobeDepth(adjustedST, v_originTextureCoordinateAndTranslate.xy, applyTranslate, dimensions, imageSize);\n\
if (globeDepth1 != 0.0 && globeDepth1 > epsilonEyeDepth)\n\
{\n\
float globeDepth2 = getGlobeDepth(adjustedST, vec2(0.0, 1.0), applyTranslate, dimensions, imageSize);\n\
if (globeDepth2 != 0.0 && globeDepth2 > epsilonEyeDepth)\n\
{\n\
float globeDepth3 = getGlobeDepth(adjustedST, vec2(1.0, 1.0), applyTranslate, dimensions, imageSize);\n\
if (globeDepth3 != 0.0 && globeDepth3 > epsilonEyeDepth)\n\
{\n\
discard;\n\
}\n\
}\n\
}\n\
}\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BillboardCollectionVS = "#ifdef INSTANCED\n\
attribute vec2 direction;\n\
#endif\n\
attribute vec4 positionHighAndScale;\n\
attribute vec4 positionLowAndRotation;\n\
attribute vec4 compressedAttribute0;\n\
attribute vec4 compressedAttribute1;\n\
attribute vec4 compressedAttribute2;\n\
attribute vec4 eyeOffset;\n\
attribute vec4 scaleByDistance;\n\
attribute vec4 pixelOffsetScaleByDistance;\n\
attribute vec4 compressedAttribute3;\n\
attribute vec2 sdf;\n\
#if defined(VERTEX_DEPTH_CHECK) || defined(FRAGMENT_DEPTH_CHECK)\n\
attribute vec4 textureCoordinateBoundsOrLabelTranslate;\n\
#endif\n\
#ifdef VECTOR_TILE\n\
attribute float a_batchId;\n\
#endif\n\
varying vec2 v_textureCoordinates;\n\
#ifdef FRAGMENT_DEPTH_CHECK\n\
varying vec4 v_textureCoordinateBounds;\n\
varying vec4 v_originTextureCoordinateAndTranslate;\n\
varying vec4 v_compressed;\n\
varying mat2 v_rotationMatrix;\n\
#endif\n\
varying vec4 v_pickColor;\n\
varying vec4 v_color;\n\
#ifdef SDF\n\
varying vec4 v_outlineColor;\n\
varying float v_outlineWidth;\n\
#endif\n\
const float UPPER_BOUND = 32768.0;\n\
const float SHIFT_LEFT16 = 65536.0;\n\
const float SHIFT_LEFT12 = 4096.0;\n\
const float SHIFT_LEFT8 = 256.0;\n\
const float SHIFT_LEFT7 = 128.0;\n\
const float SHIFT_LEFT5 = 32.0;\n\
const float SHIFT_LEFT3 = 8.0;\n\
const float SHIFT_LEFT2 = 4.0;\n\
const float SHIFT_LEFT1 = 2.0;\n\
const float SHIFT_RIGHT12 = 1.0 / 4096.0;\n\
const float SHIFT_RIGHT8 = 1.0 / 256.0;\n\
const float SHIFT_RIGHT7 = 1.0 / 128.0;\n\
const float SHIFT_RIGHT5 = 1.0 / 32.0;\n\
const float SHIFT_RIGHT3 = 1.0 / 8.0;\n\
const float SHIFT_RIGHT2 = 1.0 / 4.0;\n\
const float SHIFT_RIGHT1 = 1.0 / 2.0;\n\
vec4 addScreenSpaceOffset(vec4 positionEC, vec2 imageSize, float scale, vec2 direction, vec2 origin, vec2 translate, vec2 pixelOffset, vec3 alignedAxis, bool validAlignedAxis, float rotation, bool sizeInMeters, out mat2 rotationMatrix, out float mpp)\n\
{\n\
vec2 halfSize = imageSize * scale * 0.5;\n\
halfSize *= ((direction * 2.0) - 1.0);\n\
vec2 originTranslate = origin * abs(halfSize);\n\
#if defined(ROTATION) || defined(ALIGNED_AXIS)\n\
if (validAlignedAxis || rotation != 0.0)\n\
{\n\
float angle = rotation;\n\
if (validAlignedAxis)\n\
{\n\
vec4 projectedAlignedAxis = czm_modelViewProjection * vec4(alignedAxis, 0.0);\n\
angle += sign(-projectedAlignedAxis.x) * acos(sign(projectedAlignedAxis.y) * (projectedAlignedAxis.y * projectedAlignedAxis.y) /\n\
(projectedAlignedAxis.x * projectedAlignedAxis.x + projectedAlignedAxis.y * projectedAlignedAxis.y));\n\
}\n\
float cosTheta = cos(angle);\n\
float sinTheta = sin(angle);\n\
rotationMatrix = mat2(cosTheta, sinTheta, -sinTheta, cosTheta);\n\
halfSize = rotationMatrix * halfSize;\n\
}\n\
else\n\
{\n\
rotationMatrix = mat2(1.0, 0.0, 0.0, 1.0);\n\
}\n\
#endif\n\
mpp = czm_metersPerPixel(positionEC);\n\
positionEC.xy += (originTranslate + halfSize) * czm_branchFreeTernary(sizeInMeters, 1.0, mpp);\n\
positionEC.xy += (translate + pixelOffset) * mpp;\n\
return positionEC;\n\
}\n\
#ifdef VERTEX_DEPTH_CHECK\n\
float getGlobeDepth(vec4 positionEC)\n\
{\n\
vec4 posWC = czm_eyeToWindowCoordinates(positionEC);\n\
float globeDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, posWC.xy / czm_viewport.zw));\n\
if (globeDepth == 0.0)\n\
{\n\
return 0.0;\n\
}\n\
vec4 eyeCoordinate = czm_windowToEyeCoordinates(posWC.xy, globeDepth);\n\
return eyeCoordinate.z / eyeCoordinate.w;\n\
}\n\
#endif\n\
void main()\n\
{\n\
vec3 positionHigh = positionHighAndScale.xyz;\n\
vec3 positionLow = positionLowAndRotation.xyz;\n\
float scale = positionHighAndScale.w;\n\
#if defined(ROTATION) || defined(ALIGNED_AXIS)\n\
float rotation = positionLowAndRotation.w;\n\
#else\n\
float rotation = 0.0;\n\
#endif\n\
float compressed = compressedAttribute0.x;\n\
vec2 pixelOffset;\n\
pixelOffset.x = floor(compressed * SHIFT_RIGHT7);\n\
compressed -= pixelOffset.x * SHIFT_LEFT7;\n\
pixelOffset.x -= UPPER_BOUND;\n\
vec2 origin;\n\
origin.x = floor(compressed * SHIFT_RIGHT5);\n\
compressed -= origin.x * SHIFT_LEFT5;\n\
origin.y = floor(compressed * SHIFT_RIGHT3);\n\
compressed -= origin.y * SHIFT_LEFT3;\n\
#ifdef FRAGMENT_DEPTH_CHECK\n\
vec2 depthOrigin = origin.xy;\n\
#endif\n\
origin -= vec2(1.0);\n\
float show = floor(compressed * SHIFT_RIGHT2);\n\
compressed -= show * SHIFT_LEFT2;\n\
#ifdef INSTANCED\n\
vec2 textureCoordinatesBottomLeft = czm_decompressTextureCoordinates(compressedAttribute0.w);\n\
vec2 textureCoordinatesRange = czm_decompressTextureCoordinates(eyeOffset.w);\n\
vec2 textureCoordinates = textureCoordinatesBottomLeft + direction * textureCoordinatesRange;\n\
#else\n\
vec2 direction;\n\
direction.x = floor(compressed * SHIFT_RIGHT1);\n\
direction.y = compressed - direction.x * SHIFT_LEFT1;\n\
vec2 textureCoordinates = czm_decompressTextureCoordinates(compressedAttribute0.w);\n\
#endif\n\
float temp = compressedAttribute0.y  * SHIFT_RIGHT8;\n\
pixelOffset.y = -(floor(temp) - UPPER_BOUND);\n\
vec2 translate;\n\
translate.y = (temp - floor(temp)) * SHIFT_LEFT16;\n\
temp = compressedAttribute0.z * SHIFT_RIGHT8;\n\
translate.x = floor(temp) - UPPER_BOUND;\n\
translate.y += (temp - floor(temp)) * SHIFT_LEFT8;\n\
translate.y -= UPPER_BOUND;\n\
temp = compressedAttribute1.x * SHIFT_RIGHT8;\n\
float temp2 = floor(compressedAttribute2.w * SHIFT_RIGHT2);\n\
vec2 imageSize = vec2(floor(temp), temp2);\n\
#ifdef FRAGMENT_DEPTH_CHECK\n\
float labelHorizontalOrigin = floor(compressedAttribute2.w - (temp2 * SHIFT_LEFT2));\n\
float applyTranslate = 0.0;\n\
if (labelHorizontalOrigin != 0.0)\n\
{\n\
applyTranslate = 1.0;\n\
labelHorizontalOrigin -= 2.0;\n\
depthOrigin.x = labelHorizontalOrigin + 1.0;\n\
}\n\
depthOrigin = vec2(1.0) - (depthOrigin * 0.5);\n\
#endif\n\
#ifdef EYE_DISTANCE_TRANSLUCENCY\n\
vec4 translucencyByDistance;\n\
translucencyByDistance.x = compressedAttribute1.z;\n\
translucencyByDistance.z = compressedAttribute1.w;\n\
translucencyByDistance.y = ((temp - floor(temp)) * SHIFT_LEFT8) / 255.0;\n\
temp = compressedAttribute1.y * SHIFT_RIGHT8;\n\
translucencyByDistance.w = ((temp - floor(temp)) * SHIFT_LEFT8) / 255.0;\n\
#endif\n\
#if defined(VERTEX_DEPTH_CHECK) || defined(FRAGMENT_DEPTH_CHECK)\n\
temp = compressedAttribute3.w;\n\
temp = temp * SHIFT_RIGHT12;\n\
vec2 dimensions;\n\
dimensions.y = (temp - floor(temp)) * SHIFT_LEFT12;\n\
dimensions.x = floor(temp);\n\
#endif\n\
#ifdef ALIGNED_AXIS\n\
vec3 alignedAxis = czm_octDecode(floor(compressedAttribute1.y * SHIFT_RIGHT8));\n\
temp = compressedAttribute2.z * SHIFT_RIGHT5;\n\
bool validAlignedAxis = (temp - floor(temp)) * SHIFT_LEFT1 > 0.0;\n\
#else\n\
vec3 alignedAxis = vec3(0.0);\n\
bool validAlignedAxis = false;\n\
#endif\n\
vec4 pickColor;\n\
vec4 color;\n\
temp = compressedAttribute2.y;\n\
temp = temp * SHIFT_RIGHT8;\n\
pickColor.b = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
pickColor.g = (temp - floor(temp)) * SHIFT_LEFT8;\n\
pickColor.r = floor(temp);\n\
temp = compressedAttribute2.x;\n\
temp = temp * SHIFT_RIGHT8;\n\
color.b = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
color.g = (temp - floor(temp)) * SHIFT_LEFT8;\n\
color.r = floor(temp);\n\
temp = compressedAttribute2.z * SHIFT_RIGHT8;\n\
bool sizeInMeters = floor((temp - floor(temp)) * SHIFT_LEFT7) > 0.0;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
pickColor.a = (temp - floor(temp)) * SHIFT_LEFT8;\n\
pickColor /= 255.0;\n\
color.a = floor(temp);\n\
color /= 255.0;\n\
vec4 p = czm_translateRelativeToEye(positionHigh, positionLow);\n\
vec4 positionEC = czm_modelViewRelativeToEye * p;\n\
#if defined(FRAGMENT_DEPTH_CHECK) || defined(VERTEX_DEPTH_CHECK)\n\
float eyeDepth = positionEC.z;\n\
#endif\n\
positionEC = czm_eyeOffset(positionEC, eyeOffset.xyz);\n\
positionEC.xyz *= show;\n\
#if defined(EYE_DISTANCE_SCALING) || defined(EYE_DISTANCE_TRANSLUCENCY) || defined(EYE_DISTANCE_PIXEL_OFFSET) || defined(DISTANCE_DISPLAY_CONDITION) || defined(DISABLE_DEPTH_DISTANCE)\n\
float lengthSq;\n\
if (czm_sceneMode == czm_sceneMode2D)\n\
{\n\
lengthSq = czm_eyeHeight2D.y;\n\
}\n\
else\n\
{\n\
lengthSq = dot(positionEC.xyz, positionEC.xyz);\n\
}\n\
#endif\n\
#ifdef EYE_DISTANCE_SCALING\n\
float distanceScale = czm_nearFarScalar(scaleByDistance, lengthSq);\n\
scale *= distanceScale;\n\
translate *= distanceScale;\n\
if (scale == 0.0)\n\
{\n\
positionEC.xyz = vec3(0.0);\n\
}\n\
#endif\n\
float translucency = 1.0;\n\
#ifdef EYE_DISTANCE_TRANSLUCENCY\n\
translucency = czm_nearFarScalar(translucencyByDistance, lengthSq);\n\
if (translucency == 0.0)\n\
{\n\
positionEC.xyz = vec3(0.0);\n\
}\n\
#endif\n\
#ifdef EYE_DISTANCE_PIXEL_OFFSET\n\
float pixelOffsetScale = czm_nearFarScalar(pixelOffsetScaleByDistance, lengthSq);\n\
pixelOffset *= pixelOffsetScale;\n\
#endif\n\
#ifdef DISTANCE_DISPLAY_CONDITION\n\
float nearSq = compressedAttribute3.x;\n\
float farSq = compressedAttribute3.y;\n\
if (lengthSq < nearSq || lengthSq > farSq)\n\
{\n\
positionEC.xyz = vec3(0.0);\n\
}\n\
#endif\n\
mat2 rotationMatrix;\n\
float mpp;\n\
#ifdef DISABLE_DEPTH_DISTANCE\n\
float disableDepthTestDistance = compressedAttribute3.z;\n\
#endif\n\
#ifdef VERTEX_DEPTH_CHECK\n\
if (lengthSq < disableDepthTestDistance) {\n\
float depthsilon = 10.0;\n\
vec2 labelTranslate = textureCoordinateBoundsOrLabelTranslate.xy;\n\
vec4 pEC1 = addScreenSpaceOffset(positionEC, dimensions, scale, vec2(0.0), origin, labelTranslate, pixelOffset, alignedAxis, validAlignedAxis, rotation, sizeInMeters, rotationMatrix, mpp);\n\
float globeDepth1 = getGlobeDepth(pEC1);\n\
if (globeDepth1 != 0.0 && pEC1.z + depthsilon < globeDepth1)\n\
{\n\
vec4 pEC2 = addScreenSpaceOffset(positionEC, dimensions, scale, vec2(0.0, 1.0), origin, labelTranslate, pixelOffset, alignedAxis, validAlignedAxis, rotation, sizeInMeters, rotationMatrix, mpp);\n\
float globeDepth2 = getGlobeDepth(pEC2);\n\
if (globeDepth2 != 0.0 && pEC2.z + depthsilon < globeDepth2)\n\
{\n\
vec4 pEC3 = addScreenSpaceOffset(positionEC, dimensions, scale, vec2(1.0), origin, labelTranslate, pixelOffset, alignedAxis, validAlignedAxis, rotation, sizeInMeters, rotationMatrix, mpp);\n\
float globeDepth3 = getGlobeDepth(pEC3);\n\
if (globeDepth3 != 0.0 && pEC3.z + depthsilon < globeDepth3)\n\
{\n\
positionEC.xyz = vec3(0.0);\n\
}\n\
}\n\
}\n\
}\n\
#endif\n\
positionEC = addScreenSpaceOffset(positionEC, imageSize, scale, direction, origin, translate, pixelOffset, alignedAxis, validAlignedAxis, rotation, sizeInMeters, rotationMatrix, mpp);\n\
gl_Position = czm_projection * positionEC;\n\
v_textureCoordinates = textureCoordinates;\n\
#ifdef LOG_DEPTH\n\
czm_vertexLogDepth();\n\
#endif\n\
#ifdef DISABLE_DEPTH_DISTANCE\n\
if (disableDepthTestDistance == 0.0 && czm_minimumDisableDepthTestDistance != 0.0)\n\
{\n\
disableDepthTestDistance = czm_minimumDisableDepthTestDistance;\n\
}\n\
if (disableDepthTestDistance != 0.0)\n\
{\n\
float zclip = gl_Position.z / gl_Position.w;\n\
bool clipped = (zclip < -1.0 || zclip > 1.0);\n\
if (!clipped && (disableDepthTestDistance < 0.0 || (lengthSq > 0.0 && lengthSq < disableDepthTestDistance)))\n\
{\n\
gl_Position.z = -gl_Position.w;\n\
#ifdef LOG_DEPTH\n\
v_depthFromNearPlusOne = 1.0;\n\
#endif\n\
}\n\
}\n\
#endif\n\
#ifdef FRAGMENT_DEPTH_CHECK\n\
if (sizeInMeters) {\n\
translate /= mpp;\n\
dimensions /= mpp;\n\
imageSize /= mpp;\n\
}\n\
#if defined(ROTATION) || defined(ALIGNED_AXIS)\n\
v_rotationMatrix = rotationMatrix;\n\
#else\n\
v_rotationMatrix = mat2(1.0, 0.0, 0.0, 1.0);\n\
#endif\n\
float enableDepthCheck = 0.0;\n\
if (lengthSq < disableDepthTestDistance)\n\
{\n\
enableDepthCheck = 1.0;\n\
}\n\
float dw = floor(clamp(dimensions.x, 0.0, SHIFT_LEFT12));\n\
float dh = floor(clamp(dimensions.y, 0.0, SHIFT_LEFT12));\n\
float iw = floor(clamp(imageSize.x, 0.0, SHIFT_LEFT12));\n\
float ih = floor(clamp(imageSize.y, 0.0, SHIFT_LEFT12));\n\
v_compressed.x = eyeDepth;\n\
v_compressed.y = applyTranslate * SHIFT_LEFT1 + enableDepthCheck;\n\
v_compressed.z = dw * SHIFT_LEFT12 + dh;\n\
v_compressed.w = iw * SHIFT_LEFT12 + ih;\n\
v_originTextureCoordinateAndTranslate.xy = depthOrigin;\n\
v_originTextureCoordinateAndTranslate.zw = translate;\n\
v_textureCoordinateBounds = textureCoordinateBoundsOrLabelTranslate;\n\
#endif\n\
#ifdef SDF\n\
vec4 outlineColor;\n\
float outlineWidth;\n\
temp = sdf.x;\n\
temp = temp * SHIFT_RIGHT8;\n\
outlineColor.b = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
outlineColor.g = (temp - floor(temp)) * SHIFT_LEFT8;\n\
outlineColor.r = floor(temp);\n\
temp = sdf.y;\n\
temp = temp * SHIFT_RIGHT8;\n\
float temp3 = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
outlineWidth = (temp - floor(temp)) * SHIFT_LEFT8;\n\
outlineColor.a = floor(temp);\n\
outlineColor /= 255.0;\n\
v_outlineWidth = outlineWidth / 255.0;\n\
v_outlineColor = outlineColor;\n\
v_outlineColor.a *= translucency;\n\
#endif\n\
v_pickColor = pickColor;\n\
v_color = color;\n\
v_color.a *= translucency;\n\
}\n\
";

  /**
   * Functions that do scene-dependent transforms between rendering-related coordinate systems.
   *
   * @namespace SceneTransforms
   */
  var SceneTransforms = {};

  var actualPositionScratch = new Cartesian4(0, 0, 0, 1);
  var positionCC = new Cartesian4();
  var scratchViewport$1 = new BoundingRectangle();

  var scratchWindowCoord0 = new Cartesian2();
  var scratchWindowCoord1 = new Cartesian2();

  /**
   * Transforms a position in WGS84 coordinates to window coordinates.  This is commonly used to place an
   * HTML element at the same screen position as an object in the scene.
   *
   * @param {Scene} scene The scene.
   * @param {Cartesian3} position The position in WGS84 (world) coordinates.
   * @param {Cartesian2} [result] An optional object to return the input position transformed to window coordinates.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.  This may be <code>undefined</code> if the input position is near the center of the ellipsoid.
   *
   * @example
   * // Output the window position of longitude/latitude (0, 0) every time the mouse moves.
   * var scene = widget.scene;
   * var ellipsoid = scene.globe.ellipsoid;
   * var position = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
   * handler.setInputAction(function(movement) {
   *     console.log(Cesium.SceneTransforms.wgs84ToWindowCoordinates(scene, position));
   * }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
   */
  SceneTransforms.wgs84ToWindowCoordinates = function (scene, position, result) {
    return SceneTransforms.wgs84WithEyeOffsetToWindowCoordinates(
      scene,
      position,
      Cartesian3.ZERO,
      result
    );
  };

  var scratchCartesian4$3 = new Cartesian4();
  var scratchEyeOffset = new Cartesian3();

  function worldToClip(position, eyeOffset, camera, result) {
    var viewMatrix = camera.viewMatrix;

    var positionEC = Matrix4.multiplyByVector(
      viewMatrix,
      Cartesian4.fromElements(
        position.x,
        position.y,
        position.z,
        1,
        scratchCartesian4$3
      ),
      scratchCartesian4$3
    );

    var zEyeOffset = Cartesian3.multiplyComponents(
      eyeOffset,
      Cartesian3.normalize(positionEC, scratchEyeOffset),
      scratchEyeOffset
    );
    positionEC.x += eyeOffset.x + zEyeOffset.x;
    positionEC.y += eyeOffset.y + zEyeOffset.y;
    positionEC.z += zEyeOffset.z;

    return Matrix4.multiplyByVector(
      camera.frustum.projectionMatrix,
      positionEC,
      result
    );
  }

  var scratchMaxCartographic = new Cartographic(Math.PI, CesiumMath.PI_OVER_TWO);
  var scratchProjectedCartesian = new Cartesian3();
  var scratchCameraPosition = new Cartesian3();

  /**
   * @private
   */
  SceneTransforms.wgs84WithEyeOffsetToWindowCoordinates = function (
    scene,
    position,
    eyeOffset,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    if (!defined(position)) {
      throw new DeveloperError("position is required.");
    }
    //>>includeEnd('debug');

    // Transform for 3D, 2D, or Columbus view
    var frameState = scene.frameState;
    var actualPosition = SceneTransforms.computeActualWgs84Position(
      frameState,
      position,
      actualPositionScratch
    );

    if (!defined(actualPosition)) {
      return undefined;
    }

    // Assuming viewport takes up the entire canvas...
    var canvas = scene.canvas;
    var viewport = scratchViewport$1;
    viewport.x = 0;
    viewport.y = 0;
    viewport.width = canvas.clientWidth;
    viewport.height = canvas.clientHeight;

    var camera = scene.camera;
    var cameraCentered = false;

    if (frameState.mode === SceneMode$1.SCENE2D) {
      var projection = scene.mapProjection;
      var maxCartographic = scratchMaxCartographic;
      var maxCoord = projection.project(
        maxCartographic,
        scratchProjectedCartesian
      );

      var cameraPosition = Cartesian3.clone(
        camera.position,
        scratchCameraPosition
      );
      var frustum = camera.frustum.clone();

      var viewportTransformation = Matrix4.computeViewportTransformation(
        viewport,
        0.0,
        1.0,
        new Matrix4()
      );
      var projectionMatrix = camera.frustum.projectionMatrix;

      var x = camera.positionWC.y;
      var eyePoint = Cartesian3.fromElements(
        CesiumMath.sign(x) * maxCoord.x - x,
        0.0,
        -camera.positionWC.x
      );
      var windowCoordinates = Transforms.pointToGLWindowCoordinates(
        projectionMatrix,
        viewportTransformation,
        eyePoint
      );

      if (
        x === 0.0 ||
        windowCoordinates.x <= 0.0 ||
        windowCoordinates.x >= canvas.clientWidth
      ) {
        cameraCentered = true;
      } else {
        if (windowCoordinates.x > canvas.clientWidth * 0.5) {
          viewport.width = windowCoordinates.x;

          camera.frustum.right = maxCoord.x - x;

          positionCC = worldToClip(actualPosition, eyeOffset, camera, positionCC);
          SceneTransforms.clipToGLWindowCoordinates(
            viewport,
            positionCC,
            scratchWindowCoord0
          );

          viewport.x += windowCoordinates.x;

          camera.position.x = -camera.position.x;

          var right = camera.frustum.right;
          camera.frustum.right = -camera.frustum.left;
          camera.frustum.left = -right;

          positionCC = worldToClip(actualPosition, eyeOffset, camera, positionCC);
          SceneTransforms.clipToGLWindowCoordinates(
            viewport,
            positionCC,
            scratchWindowCoord1
          );
        } else {
          viewport.x += windowCoordinates.x;
          viewport.width -= windowCoordinates.x;

          camera.frustum.left = -maxCoord.x - x;

          positionCC = worldToClip(actualPosition, eyeOffset, camera, positionCC);
          SceneTransforms.clipToGLWindowCoordinates(
            viewport,
            positionCC,
            scratchWindowCoord0
          );

          viewport.x = viewport.x - viewport.width;

          camera.position.x = -camera.position.x;

          var left = camera.frustum.left;
          camera.frustum.left = -camera.frustum.right;
          camera.frustum.right = -left;

          positionCC = worldToClip(actualPosition, eyeOffset, camera, positionCC);
          SceneTransforms.clipToGLWindowCoordinates(
            viewport,
            positionCC,
            scratchWindowCoord1
          );
        }

        Cartesian3.clone(cameraPosition, camera.position);
        camera.frustum = frustum.clone();

        result = Cartesian2.clone(scratchWindowCoord0, result);
        if (result.x < 0.0 || result.x > canvas.clientWidth) {
          result.x = scratchWindowCoord1.x;
        }
      }
    }

    if (frameState.mode !== SceneMode$1.SCENE2D || cameraCentered) {
      // View-projection matrix to transform from world coordinates to clip coordinates
      positionCC = worldToClip(actualPosition, eyeOffset, camera, positionCC);
      if (
        positionCC.z < 0 &&
        !(camera.frustum instanceof OrthographicFrustum) &&
        !(camera.frustum instanceof OrthographicOffCenterFrustum)
      ) {
        return undefined;
      }

      result = SceneTransforms.clipToGLWindowCoordinates(
        viewport,
        positionCC,
        result
      );
    }

    result.y = canvas.clientHeight - result.y;
    return result;
  };

  /**
   * Transforms a position in WGS84 coordinates to drawing buffer coordinates.  This may produce different
   * results from SceneTransforms.wgs84ToWindowCoordinates when the browser zoom is not 100%, or on high-DPI displays.
   *
   * @param {Scene} scene The scene.
   * @param {Cartesian3} position The position in WGS84 (world) coordinates.
   * @param {Cartesian2} [result] An optional object to return the input position transformed to window coordinates.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.  This may be <code>undefined</code> if the input position is near the center of the ellipsoid.
   *
   * @example
   * // Output the window position of longitude/latitude (0, 0) every time the mouse moves.
   * var scene = widget.scene;
   * var ellipsoid = scene.globe.ellipsoid;
   * var position = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
   * handler.setInputAction(function(movement) {
   *     console.log(Cesium.SceneTransforms.wgs84ToWindowCoordinates(scene, position));
   * }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
   */
  SceneTransforms.wgs84ToDrawingBufferCoordinates = function (
    scene,
    position,
    result
  ) {
    result = SceneTransforms.wgs84ToWindowCoordinates(scene, position, result);
    if (!defined(result)) {
      return undefined;
    }

    return SceneTransforms.transformWindowToDrawingBuffer(scene, result, result);
  };

  var projectedPosition = new Cartesian3();
  var positionInCartographic = new Cartographic();

  /**
   * @private
   */
  SceneTransforms.computeActualWgs84Position = function (
    frameState,
    position,
    result
  ) {
    var mode = frameState.mode;

    if (mode === SceneMode$1.SCENE3D) {
      return Cartesian3.clone(position, result);
    }

    var projection = frameState.mapProjection;
    var cartographic = projection.ellipsoid.cartesianToCartographic(
      position,
      positionInCartographic
    );
    if (!defined(cartographic)) {
      return undefined;
    }

    projection.project(cartographic, projectedPosition);

    if (mode === SceneMode$1.COLUMBUS_VIEW) {
      return Cartesian3.fromElements(
        projectedPosition.z,
        projectedPosition.x,
        projectedPosition.y,
        result
      );
    }

    if (mode === SceneMode$1.SCENE2D) {
      return Cartesian3.fromElements(
        0.0,
        projectedPosition.x,
        projectedPosition.y,
        result
      );
    }

    // mode === SceneMode.MORPHING
    var morphTime = frameState.morphTime;
    return Cartesian3.fromElements(
      CesiumMath.lerp(projectedPosition.z, position.x, morphTime),
      CesiumMath.lerp(projectedPosition.x, position.y, morphTime),
      CesiumMath.lerp(projectedPosition.y, position.z, morphTime),
      result
    );
  };

  var positionNDC = new Cartesian3();
  var positionWC = new Cartesian3();
  var viewportTransform = new Matrix4();

  /**
   * @private
   */
  SceneTransforms.clipToGLWindowCoordinates = function (
    viewport,
    position,
    result
  ) {
    // Perspective divide to transform from clip coordinates to normalized device coordinates
    Cartesian3.divideByScalar(position, position.w, positionNDC);

    // Viewport transform to transform from clip coordinates to window coordinates
    Matrix4.computeViewportTransformation(viewport, 0.0, 1.0, viewportTransform);
    Matrix4.multiplyByPoint(viewportTransform, positionNDC, positionWC);

    return Cartesian2.fromCartesian3(positionWC, result);
  };

  /**
   * @private
   */
  SceneTransforms.transformWindowToDrawingBuffer = function (
    scene,
    windowPosition,
    result
  ) {
    var canvas = scene.canvas;
    var xScale = scene.drawingBufferWidth / canvas.clientWidth;
    var yScale = scene.drawingBufferHeight / canvas.clientHeight;
    return Cartesian2.fromElements(
      windowPosition.x * xScale,
      windowPosition.y * yScale,
      result
    );
  };

  var scratchNDC = new Cartesian4();
  var scratchWorldCoords = new Cartesian4();

  /**
   * @private
   */
  SceneTransforms.drawingBufferToWgs84Coordinates = function (
    scene,
    drawingBufferPosition,
    depth,
    result
  ) {
    var context = scene.context;
    var uniformState = context.uniformState;

    var currentFrustum = uniformState.currentFrustum;
    var near = currentFrustum.x;
    var far = currentFrustum.y;

    if (scene.frameState.useLogDepth) {
      // transforming logarithmic depth of form
      // log2(z + 1) / log2( far + 1);
      // to perspective form
      // (far - far * near / z) / (far - near)
      var log2Depth = depth * uniformState.log2FarDepthFromNearPlusOne;
      var depthFromNear = Math.pow(2.0, log2Depth) - 1.0;
      depth = (far * (1.0 - near / (depthFromNear + near))) / (far - near);
    }

    var viewport = scene.view.passState.viewport;
    var ndc = Cartesian4.clone(Cartesian4.UNIT_W, scratchNDC);
    ndc.x = ((drawingBufferPosition.x - viewport.x) / viewport.width) * 2.0 - 1.0;
    ndc.y =
      ((drawingBufferPosition.y - viewport.y) / viewport.height) * 2.0 - 1.0;
    ndc.z = depth * 2.0 - 1.0;
    ndc.w = 1.0;

    var worldCoords;
    var frustum = scene.camera.frustum;
    if (!defined(frustum.fovy)) {
      if (defined(frustum._offCenterFrustum)) {
        frustum = frustum._offCenterFrustum;
      }
      worldCoords = scratchWorldCoords;
      worldCoords.x =
        (ndc.x * (frustum.right - frustum.left) + frustum.left + frustum.right) *
        0.5;
      worldCoords.y =
        (ndc.y * (frustum.top - frustum.bottom) + frustum.bottom + frustum.top) *
        0.5;
      worldCoords.z = (ndc.z * (near - far) - near - far) * 0.5;
      worldCoords.w = 1.0;

      worldCoords = Matrix4.multiplyByVector(
        uniformState.inverseView,
        worldCoords,
        worldCoords
      );
    } else {
      worldCoords = Matrix4.multiplyByVector(
        uniformState.inverseViewProjection,
        ndc,
        scratchWorldCoords
      );

      // Reverse perspective divide
      var w = 1.0 / worldCoords.w;
      Cartesian3.multiplyByScalar(worldCoords, w, worldCoords);
    }
    return Cartesian3.fromCartesian4(worldCoords, result);
  };

  /**
   * A viewport-aligned image positioned in the 3D scene, that is created
   * and rendered using a {@link BillboardCollection}.  A billboard is created and its initial
   * properties are set by calling {@link BillboardCollection#add}.
   * <br /><br />
   * <div align='center'>
   * <img src='Images/Billboard.png' width='400' height='300' /><br />
   * Example billboards
   * </div>
   *
   * @alias Billboard
   *
   * @performance Reading a property, e.g., {@link Billboard#show}, is constant time.
   * Assigning to a property is constant time but results in
   * CPU to GPU traffic when {@link BillboardCollection#update} is called.  The per-billboard traffic is
   * the same regardless of how many properties were updated.  If most billboards in a collection need to be
   * updated, it may be more efficient to clear the collection with {@link BillboardCollection#removeAll}
   * and add new billboards instead of modifying each one.
   *
   * @exception {DeveloperError} scaleByDistance.far must be greater than scaleByDistance.near
   * @exception {DeveloperError} translucencyByDistance.far must be greater than translucencyByDistance.near
   * @exception {DeveloperError} pixelOffsetScaleByDistance.far must be greater than pixelOffsetScaleByDistance.near
   * @exception {DeveloperError} distanceDisplayCondition.far must be greater than distanceDisplayCondition.near
   *
   * @see BillboardCollection
   * @see BillboardCollection#add
   * @see Label
   *
   * @internalConstructor
   * @class
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Billboards.html|Cesium Sandcastle Billboard Demo}
   */
  function Billboard(options, billboardCollection) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (
      defined(options.disableDepthTestDistance) &&
      options.disableDepthTestDistance < 0.0
    ) {
      throw new DeveloperError(
        "disableDepthTestDistance must be greater than or equal to 0.0."
      );
    }
    //>>includeEnd('debug');

    var translucencyByDistance = options.translucencyByDistance;
    var pixelOffsetScaleByDistance = options.pixelOffsetScaleByDistance;
    var scaleByDistance = options.scaleByDistance;
    var distanceDisplayCondition = options.distanceDisplayCondition;
    if (defined(translucencyByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (translucencyByDistance.far <= translucencyByDistance.near) {
        throw new DeveloperError(
          "translucencyByDistance.far must be greater than translucencyByDistance.near."
        );
      }
      //>>includeEnd('debug');
      translucencyByDistance = NearFarScalar.clone(translucencyByDistance);
    }
    if (defined(pixelOffsetScaleByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (pixelOffsetScaleByDistance.far <= pixelOffsetScaleByDistance.near) {
        throw new DeveloperError(
          "pixelOffsetScaleByDistance.far must be greater than pixelOffsetScaleByDistance.near."
        );
      }
      //>>includeEnd('debug');
      pixelOffsetScaleByDistance = NearFarScalar.clone(
        pixelOffsetScaleByDistance
      );
    }
    if (defined(scaleByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (scaleByDistance.far <= scaleByDistance.near) {
        throw new DeveloperError(
          "scaleByDistance.far must be greater than scaleByDistance.near."
        );
      }
      //>>includeEnd('debug');
      scaleByDistance = NearFarScalar.clone(scaleByDistance);
    }
    if (defined(distanceDisplayCondition)) {
      //>>includeStart('debug', pragmas.debug);
      if (distanceDisplayCondition.far <= distanceDisplayCondition.near) {
        throw new DeveloperError(
          "distanceDisplayCondition.far must be greater than distanceDisplayCondition.near."
        );
      }
      //>>includeEnd('debug');
      distanceDisplayCondition = DistanceDisplayCondition.clone(
        distanceDisplayCondition
      );
    }

    this._show = defaultValue(options.show, true);
    this._position = Cartesian3.clone(
      defaultValue(options.position, Cartesian3.ZERO)
    );
    this._actualPosition = Cartesian3.clone(this._position); // For columbus view and 2D
    this._pixelOffset = Cartesian2.clone(
      defaultValue(options.pixelOffset, Cartesian2.ZERO)
    );
    this._translate = new Cartesian2(0.0, 0.0); // used by labels for glyph vertex translation
    this._eyeOffset = Cartesian3.clone(
      defaultValue(options.eyeOffset, Cartesian3.ZERO)
    );
    this._heightReference = defaultValue(
      options.heightReference,
      HeightReference$1.NONE
    );
    this._verticalOrigin = defaultValue(
      options.verticalOrigin,
      VerticalOrigin$1.CENTER
    );
    this._horizontalOrigin = defaultValue(
      options.horizontalOrigin,
      HorizontalOrigin$1.CENTER
    );
    this._scale = defaultValue(options.scale, 1.0);
    this._color = Color.clone(defaultValue(options.color, Color.WHITE));
    this._rotation = defaultValue(options.rotation, 0.0);
    this._alignedAxis = Cartesian3.clone(
      defaultValue(options.alignedAxis, Cartesian3.ZERO)
    );
    this._width = options.width;
    this._height = options.height;
    this._scaleByDistance = scaleByDistance;
    this._translucencyByDistance = translucencyByDistance;
    this._pixelOffsetScaleByDistance = pixelOffsetScaleByDistance;
    this._sizeInMeters = defaultValue(options.sizeInMeters, false);
    this._distanceDisplayCondition = distanceDisplayCondition;
    this._disableDepthTestDistance = options.disableDepthTestDistance;
    this._id = options.id;
    this._collection = defaultValue(options.collection, billboardCollection);

    this._pickId = undefined;
    this._pickPrimitive = defaultValue(options._pickPrimitive, this);
    this._billboardCollection = billboardCollection;
    this._dirty = false;
    this._index = -1; //Used only by BillboardCollection
    this._batchIndex = undefined; // Used only by Vector3DTilePoints and BillboardCollection

    this._imageIndex = -1;
    this._imageIndexPromise = undefined;
    this._imageId = undefined;
    this._image = undefined;
    this._imageSubRegion = undefined;
    this._imageWidth = undefined;
    this._imageHeight = undefined;

    this._labelDimensions = undefined;
    this._labelHorizontalOrigin = undefined;
    this._labelTranslate = undefined;

    var image = options.image;
    var imageId = options.imageId;
    if (defined(image)) {
      if (!defined(imageId)) {
        if (typeof image === "string") {
          imageId = image;
        } else if (defined(image.src)) {
          imageId = image.src;
        } else {
          imageId = createGuid();
        }
      }

      this._imageId = imageId;
      this._image = image;
    }

    if (defined(options.imageSubRegion)) {
      this._imageId = imageId;
      this._imageSubRegion = options.imageSubRegion;
    }

    if (defined(this._billboardCollection._textureAtlas)) {
      this._loadImage();
    }

    this._actualClampedPosition = undefined;
    this._removeCallbackFunc = undefined;
    this._mode = SceneMode$1.SCENE3D;

    this._clusterShow = true;
    this._outlineColor = Color.clone(
      defaultValue(options.outlineColor, Color.BLACK)
    );
    this._outlineWidth = defaultValue(options.outlineWidth, 0.0);

    this._updateClamping();
  }

  var SHOW_INDEX = (Billboard.SHOW_INDEX = 0);
  var POSITION_INDEX = (Billboard.POSITION_INDEX = 1);
  var PIXEL_OFFSET_INDEX = (Billboard.PIXEL_OFFSET_INDEX = 2);
  var EYE_OFFSET_INDEX = (Billboard.EYE_OFFSET_INDEX = 3);
  var HORIZONTAL_ORIGIN_INDEX = (Billboard.HORIZONTAL_ORIGIN_INDEX = 4);
  var VERTICAL_ORIGIN_INDEX = (Billboard.VERTICAL_ORIGIN_INDEX = 5);
  var SCALE_INDEX = (Billboard.SCALE_INDEX = 6);
  var IMAGE_INDEX_INDEX = (Billboard.IMAGE_INDEX_INDEX = 7);
  var COLOR_INDEX = (Billboard.COLOR_INDEX = 8);
  var ROTATION_INDEX = (Billboard.ROTATION_INDEX = 9);
  var ALIGNED_AXIS_INDEX = (Billboard.ALIGNED_AXIS_INDEX = 10);
  var SCALE_BY_DISTANCE_INDEX = (Billboard.SCALE_BY_DISTANCE_INDEX = 11);
  var TRANSLUCENCY_BY_DISTANCE_INDEX = (Billboard.TRANSLUCENCY_BY_DISTANCE_INDEX = 12);
  var PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX = (Billboard.PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX = 13);
  var DISTANCE_DISPLAY_CONDITION = (Billboard.DISTANCE_DISPLAY_CONDITION = 14);
  var DISABLE_DEPTH_DISTANCE = (Billboard.DISABLE_DEPTH_DISTANCE = 15);
  Billboard.TEXTURE_COORDINATE_BOUNDS = 16;
  var SDF_INDEX = (Billboard.SDF_INDEX = 17);
  Billboard.NUMBER_OF_PROPERTIES = 18;

  function makeDirty(billboard, propertyChanged) {
    var billboardCollection = billboard._billboardCollection;
    if (defined(billboardCollection)) {
      billboardCollection._updateBillboard(billboard, propertyChanged);
      billboard._dirty = true;
    }
  }

  Object.defineProperties(Billboard.prototype, {
    /**
     * Determines if this billboard will be shown.  Use this to hide or show a billboard, instead
     * of removing it and re-adding it to the collection.
     * @memberof Billboard.prototype
     * @type {Boolean}
     * @default true
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._show !== value) {
          this._show = value;
          makeDirty(this, SHOW_INDEX);
        }
      },
    },

    /**
     * Gets or sets the Cartesian position of this billboard.
     * @memberof Billboard.prototype
     * @type {Cartesian3}
     */
    position: {
      get: function () {
        return this._position;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug)
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var position = this._position;
        if (!Cartesian3.equals(position, value)) {
          Cartesian3.clone(value, position);
          Cartesian3.clone(value, this._actualPosition);
          this._updateClamping();
          makeDirty(this, POSITION_INDEX);
        }
      },
    },

    /**
     * Gets or sets the height reference of this billboard.
     * @memberof Billboard.prototype
     * @type {HeightReference}
     * @default HeightReference.NONE
     */
    heightReference: {
      get: function () {
        return this._heightReference;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug)
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var heightReference = this._heightReference;
        if (value !== heightReference) {
          this._heightReference = value;
          this._updateClamping();
          makeDirty(this, POSITION_INDEX);
        }
      },
    },

    /**
     * Gets or sets the pixel offset in screen space from the origin of this billboard.  This is commonly used
     * to align multiple billboards and labels at the same position, e.g., an image and text.  The
     * screen space origin is the top, left corner of the canvas; <code>x</code> increases from
     * left to right, and <code>y</code> increases from top to bottom.
     * <br /><br />
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><code>default</code><br/><img src='Images/Billboard.setPixelOffset.default.png' width='250' height='188' /></td>
     * <td align='center'><code>b.pixeloffset = new Cartesian2(50, 25);</code><br/><img src='Images/Billboard.setPixelOffset.x50y-25.png' width='250' height='188' /></td>
     * </tr></table>
     * The billboard's origin is indicated by the yellow point.
     * </div>
     * @memberof Billboard.prototype
     * @type {Cartesian2}
     */
    pixelOffset: {
      get: function () {
        return this._pixelOffset;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var pixelOffset = this._pixelOffset;
        if (!Cartesian2.equals(pixelOffset, value)) {
          Cartesian2.clone(value, pixelOffset);
          makeDirty(this, PIXEL_OFFSET_INDEX);
        }
      },
    },

    /**
     * Gets or sets near and far scaling properties of a Billboard based on the billboard's distance from the camera.
     * A billboard's scale will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the billboard's scale remains clamped to the nearest bound.  If undefined,
     * scaleByDistance will be disabled.
     * @memberof Billboard.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a billboard's scaleByDistance to scale by 1.5 when the
     * // camera is 1500 meters from the billboard and disappear as
     * // the camera distance approaches 8.0e6 meters.
     * b.scaleByDistance = new Cesium.NearFarScalar(1.5e2, 1.5, 8.0e6, 0.0);
     *
     * @example
     * // Example 2.
     * // disable scaling by distance
     * b.scaleByDistance = undefined;
     */
    scaleByDistance: {
      get: function () {
        return this._scaleByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var scaleByDistance = this._scaleByDistance;
        if (!NearFarScalar.equals(scaleByDistance, value)) {
          this._scaleByDistance = NearFarScalar.clone(value, scaleByDistance);
          makeDirty(this, SCALE_BY_DISTANCE_INDEX);
        }
      },
    },

    /**
     * Gets or sets near and far translucency properties of a Billboard based on the billboard's distance from the camera.
     * A billboard's translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the billboard's translucency remains clamped to the nearest bound.  If undefined,
     * translucencyByDistance will be disabled.
     * @memberof Billboard.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a billboard's translucency to 1.0 when the
     * // camera is 1500 meters from the billboard and disappear as
     * // the camera distance approaches 8.0e6 meters.
     * b.translucencyByDistance = new Cesium.NearFarScalar(1.5e2, 1.0, 8.0e6, 0.0);
     *
     * @example
     * // Example 2.
     * // disable translucency by distance
     * b.translucencyByDistance = undefined;
     */
    translucencyByDistance: {
      get: function () {
        return this._translucencyByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var translucencyByDistance = this._translucencyByDistance;
        if (!NearFarScalar.equals(translucencyByDistance, value)) {
          this._translucencyByDistance = NearFarScalar.clone(
            value,
            translucencyByDistance
          );
          makeDirty(this, TRANSLUCENCY_BY_DISTANCE_INDEX);
        }
      },
    },

    /**
     * Gets or sets near and far pixel offset scaling properties of a Billboard based on the billboard's distance from the camera.
     * A billboard's pixel offset will be scaled between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the billboard's pixel offset scale remains clamped to the nearest bound.  If undefined,
     * pixelOffsetScaleByDistance will be disabled.
     * @memberof Billboard.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a billboard's pixel offset scale to 0.0 when the
     * // camera is 1500 meters from the billboard and scale pixel offset to 10.0 pixels
     * // in the y direction the camera distance approaches 8.0e6 meters.
     * b.pixelOffset = new Cesium.Cartesian2(0.0, 1.0);
     * b.pixelOffsetScaleByDistance = new Cesium.NearFarScalar(1.5e2, 0.0, 8.0e6, 10.0);
     *
     * @example
     * // Example 2.
     * // disable pixel offset by distance
     * b.pixelOffsetScaleByDistance = undefined;
     */
    pixelOffsetScaleByDistance: {
      get: function () {
        return this._pixelOffsetScaleByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var pixelOffsetScaleByDistance = this._pixelOffsetScaleByDistance;
        if (!NearFarScalar.equals(pixelOffsetScaleByDistance, value)) {
          this._pixelOffsetScaleByDistance = NearFarScalar.clone(
            value,
            pixelOffsetScaleByDistance
          );
          makeDirty(this, PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX);
        }
      },
    },

    /**
     * Gets or sets the 3D Cartesian offset applied to this billboard in eye coordinates.  Eye coordinates is a left-handed
     * coordinate system, where <code>x</code> points towards the viewer's right, <code>y</code> points up, and
     * <code>z</code> points into the screen.  Eye coordinates use the same scale as world and model coordinates,
     * which is typically meters.
     * <br /><br />
     * An eye offset is commonly used to arrange multiple billboards or objects at the same position, e.g., to
     * arrange a billboard above its corresponding 3D model.
     * <br /><br />
     * Below, the billboard is positioned at the center of the Earth but an eye offset makes it always
     * appear on top of the Earth regardless of the viewer's or Earth's orientation.
     * <br /><br />
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.one.png' width='250' height='188' /></td>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.two.png' width='250' height='188' /></td>
     * </tr></table>
     * <code>b.eyeOffset = new Cartesian3(0.0, 8000000.0, 0.0);</code><br /><br />
     * </div>
     * @memberof Billboard.prototype
     * @type {Cartesian3}
     */
    eyeOffset: {
      get: function () {
        return this._eyeOffset;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var eyeOffset = this._eyeOffset;
        if (!Cartesian3.equals(eyeOffset, value)) {
          Cartesian3.clone(value, eyeOffset);
          makeDirty(this, EYE_OFFSET_INDEX);
        }
      },
    },

    /**
     * Gets or sets the horizontal origin of this billboard, which determines if the billboard is
     * to the left, center, or right of its anchor position.
     * <br /><br />
     * <div align='center'>
     * <img src='Images/Billboard.setHorizontalOrigin.png' width='648' height='196' /><br />
     * </div>
     * @memberof Billboard.prototype
     * @type {HorizontalOrigin}
     * @example
     * // Use a bottom, left origin
     * b.horizontalOrigin = Cesium.HorizontalOrigin.LEFT;
     * b.verticalOrigin = Cesium.VerticalOrigin.BOTTOM;
     */
    horizontalOrigin: {
      get: function () {
        return this._horizontalOrigin;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._horizontalOrigin !== value) {
          this._horizontalOrigin = value;
          makeDirty(this, HORIZONTAL_ORIGIN_INDEX);
        }
      },
    },

    /**
     * Gets or sets the vertical origin of this billboard, which determines if the billboard is
     * to the above, below, or at the center of its anchor position.
     * <br /><br />
     * <div align='center'>
     * <img src='Images/Billboard.setVerticalOrigin.png' width='695' height='175' /><br />
     * </div>
     * @memberof Billboard.prototype
     * @type {VerticalOrigin}
     * @example
     * // Use a bottom, left origin
     * b.horizontalOrigin = Cesium.HorizontalOrigin.LEFT;
     * b.verticalOrigin = Cesium.VerticalOrigin.BOTTOM;
     */
    verticalOrigin: {
      get: function () {
        return this._verticalOrigin;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._verticalOrigin !== value) {
          this._verticalOrigin = value;
          makeDirty(this, VERTICAL_ORIGIN_INDEX);
        }
      },
    },

    /**
     * Gets or sets the uniform scale that is multiplied with the billboard's image size in pixels.
     * A scale of <code>1.0</code> does not change the size of the billboard; a scale greater than
     * <code>1.0</code> enlarges the billboard; a positive scale less than <code>1.0</code> shrinks
     * the billboard.
     * <br /><br />
     * <div align='center'>
     * <img src='Images/Billboard.setScale.png' width='400' height='300' /><br/>
     * From left to right in the above image, the scales are <code>0.5</code>, <code>1.0</code>,
     * and <code>2.0</code>.
     * </div>
     * @memberof Billboard.prototype
     * @type {Number}
     */
    scale: {
      get: function () {
        return this._scale;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._scale !== value) {
          this._scale = value;
          makeDirty(this, SCALE_INDEX);
        }
      },
    },

    /**
     * Gets or sets the color that is multiplied with the billboard's texture.  This has two common use cases.  First,
     * the same white texture may be used by many different billboards, each with a different color, to create
     * colored billboards.  Second, the color's alpha component can be used to make the billboard translucent as shown below.
     * An alpha of <code>0.0</code> makes the billboard transparent, and <code>1.0</code> makes the billboard opaque.
     * <br /><br />
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><code>default</code><br/><img src='Images/Billboard.setColor.Alpha255.png' width='250' height='188' /></td>
     * <td align='center'><code>alpha : 0.5</code><br/><img src='Images/Billboard.setColor.Alpha127.png' width='250' height='188' /></td>
     * </tr></table>
     * </div>
     * <br />
     * The red, green, blue, and alpha values are indicated by <code>value</code>'s <code>red</code>, <code>green</code>,
     * <code>blue</code>, and <code>alpha</code> properties as shown in Example 1.  These components range from <code>0.0</code>
     * (no intensity) to <code>1.0</code> (full intensity).
     * @memberof Billboard.prototype
     * @type {Color}
     *
     * @example
     * // Example 1. Assign yellow.
     * b.color = Cesium.Color.YELLOW;
     *
     * @example
     * // Example 2. Make a billboard 50% translucent.
     * b.color = new Cesium.Color(1.0, 1.0, 1.0, 0.5);
     */
    color: {
      get: function () {
        return this._color;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var color = this._color;
        if (!Color.equals(color, value)) {
          Color.clone(value, color);
          makeDirty(this, COLOR_INDEX);
        }
      },
    },

    /**
     * Gets or sets the rotation angle in radians.
     * @memberof Billboard.prototype
     * @type {Number}
     */
    rotation: {
      get: function () {
        return this._rotation;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._rotation !== value) {
          this._rotation = value;
          makeDirty(this, ROTATION_INDEX);
        }
      },
    },

    /**
     * Gets or sets the aligned axis in world space. The aligned axis is the unit vector that the billboard up vector points towards.
     * The default is the zero vector, which means the billboard is aligned to the screen up vector.
     * @memberof Billboard.prototype
     * @type {Cartesian3}
     * @example
     * // Example 1.
     * // Have the billboard up vector point north
     * billboard.alignedAxis = Cesium.Cartesian3.UNIT_Z;
     *
     * @example
     * // Example 2.
     * // Have the billboard point east.
     * billboard.alignedAxis = Cesium.Cartesian3.UNIT_Z;
     * billboard.rotation = -Cesium.Math.PI_OVER_TWO;
     *
     * @example
     * // Example 3.
     * // Reset the aligned axis
     * billboard.alignedAxis = Cesium.Cartesian3.ZERO;
     */
    alignedAxis: {
      get: function () {
        return this._alignedAxis;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var alignedAxis = this._alignedAxis;
        if (!Cartesian3.equals(alignedAxis, value)) {
          Cartesian3.clone(value, alignedAxis);
          makeDirty(this, ALIGNED_AXIS_INDEX);
        }
      },
    },

    /**
     * Gets or sets a width for the billboard. If undefined, the image width will be used.
     * @memberof Billboard.prototype
     * @type {Number}
     */
    width: {
      get: function () {
        return defaultValue(this._width, this._imageWidth);
      },
      set: function (value) {
        if (this._width !== value) {
          this._width = value;
          makeDirty(this, IMAGE_INDEX_INDEX);
        }
      },
    },

    /**
     * Gets or sets a height for the billboard. If undefined, the image height will be used.
     * @memberof Billboard.prototype
     * @type {Number}
     */
    height: {
      get: function () {
        return defaultValue(this._height, this._imageHeight);
      },
      set: function (value) {
        if (this._height !== value) {
          this._height = value;
          makeDirty(this, IMAGE_INDEX_INDEX);
        }
      },
    },

    /**
     * Gets or sets if the billboard size is in meters or pixels. <code>true</code> to size the billboard in meters;
     * otherwise, the size is in pixels.
     * @memberof Billboard.prototype
     * @type {Boolean}
     * @default false
     */
    sizeInMeters: {
      get: function () {
        return this._sizeInMeters;
      },
      set: function (value) {
        if (this._sizeInMeters !== value) {
          this._sizeInMeters = value;
          makeDirty(this, COLOR_INDEX);
        }
      },
    },

    /**
     * Gets or sets the condition specifying at what distance from the camera that this billboard will be displayed.
     * @memberof Billboard.prototype
     * @type {DistanceDisplayCondition}
     * @default undefined
     */
    distanceDisplayCondition: {
      get: function () {
        return this._distanceDisplayCondition;
      },
      set: function (value) {
        if (
          !DistanceDisplayCondition.equals(value, this._distanceDisplayCondition)
        ) {
          //>>includeStart('debug', pragmas.debug);
          if (defined(value) && value.far <= value.near) {
            throw new DeveloperError(
              "far distance must be greater than near distance."
            );
          }
          //>>includeEnd('debug');
          this._distanceDisplayCondition = DistanceDisplayCondition.clone(
            value,
            this._distanceDisplayCondition
          );
          makeDirty(this, DISTANCE_DISPLAY_CONDITION);
        }
      },
    },

    /**
     * Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
     * When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.
     * @memberof Billboard.prototype
     * @type {Number}
     */
    disableDepthTestDistance: {
      get: function () {
        return this._disableDepthTestDistance;
      },
      set: function (value) {
        if (this._disableDepthTestDistance !== value) {
          //>>includeStart('debug', pragmas.debug);
          if (defined(value) && value < 0.0) {
            throw new DeveloperError(
              "disableDepthTestDistance must be greater than or equal to 0.0."
            );
          }
          //>>includeEnd('debug');
          this._disableDepthTestDistance = value;
          makeDirty(this, DISABLE_DEPTH_DISTANCE);
        }
      },
    },

    /**
     * Gets or sets the user-defined object returned when the billboard is picked.
     * @memberof Billboard.prototype
     * @type {Object}
     */
    id: {
      get: function () {
        return this._id;
      },
      set: function (value) {
        this._id = value;
        if (defined(this._pickId)) {
          this._pickId.object.id = value;
        }
      },
    },

    /**
     * The primitive to return when picking this billboard.
     * @memberof Billboard.prototype
     * @private
     */
    pickPrimitive: {
      get: function () {
        return this._pickPrimitive;
      },
      set: function (value) {
        this._pickPrimitive = value;
        if (defined(this._pickId)) {
          this._pickId.object.primitive = value;
        }
      },
    },

    /**
     * @private
     */
    pickId: {
      get: function () {
        return this._pickId;
      },
    },

    /**
     * <p>
     * Gets or sets the image to be used for this billboard.  If a texture has already been created for the
     * given image, the existing texture is used.
     * </p>
     * <p>
     * This property can be set to a loaded Image, a URL which will be loaded as an Image automatically,
     * a canvas, or another billboard's image property (from the same billboard collection).
     * </p>
     *
     * @memberof Billboard.prototype
     * @type {String}
     * @example
     * // load an image from a URL
     * b.image = 'some/image/url.png';
     *
     * // assuming b1 and b2 are billboards in the same billboard collection,
     * // use the same image for both billboards.
     * b2.image = b1.image;
     */
    image: {
      get: function () {
        return this._imageId;
      },
      set: function (value) {
        if (!defined(value)) {
          this._imageIndex = -1;
          this._imageSubRegion = undefined;
          this._imageId = undefined;
          this._image = undefined;
          this._imageIndexPromise = undefined;
          makeDirty(this, IMAGE_INDEX_INDEX);
        } else if (typeof value === "string") {
          this.setImage(value, value);
        } else if (value instanceof Resource) {
          this.setImage(value.url, value);
        } else if (defined(value.src)) {
          this.setImage(value.src, value);
        } else {
          this.setImage(createGuid(), value);
        }
      },
    },

    /**
     * When <code>true</code>, this billboard is ready to render, i.e., the image
     * has been downloaded and the WebGL resources are created.
     *
     * @memberof Billboard.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    ready: {
      get: function () {
        return this._imageIndex !== -1;
      },
    },

    /**
     * Keeps track of the position of the billboard based on the height reference.
     * @memberof Billboard.prototype
     * @type {Cartesian3}
     * @private
     */
    _clampedPosition: {
      get: function () {
        return this._actualClampedPosition;
      },
      set: function (value) {
        this._actualClampedPosition = Cartesian3.clone(
          value,
          this._actualClampedPosition
        );
        makeDirty(this, POSITION_INDEX);
      },
    },

    /**
     * Determines whether or not this billboard will be shown or hidden because it was clustered.
     * @memberof Billboard.prototype
     * @type {Boolean}
     * @private
     */
    clusterShow: {
      get: function () {
        return this._clusterShow;
      },
      set: function (value) {
        if (this._clusterShow !== value) {
          this._clusterShow = value;
          makeDirty(this, SHOW_INDEX);
        }
      },
    },

    /**
     * The outline color of this Billboard.  Effective only for SDF billboards like Label glyphs.
     * @memberof Billboard.prototype
     * @type {Color}
     * @private
     */
    outlineColor: {
      get: function () {
        return this._outlineColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var outlineColor = this._outlineColor;
        if (!Color.equals(outlineColor, value)) {
          Color.clone(value, outlineColor);
          makeDirty(this, SDF_INDEX);
        }
      },
    },

    /**
     * The outline width of this Billboard in pixels.  Effective only for SDF billboards like Label glyphs.
     * @memberof Billboard.prototype
     * @type {Number}
     * @private
     */
    outlineWidth: {
      get: function () {
        return this._outlineWidth;
      },
      set: function (value) {
        if (this._outlineWidth !== value) {
          this._outlineWidth = value;
          makeDirty(this, SDF_INDEX);
        }
      },
    },
  });

  Billboard.prototype.getPickId = function (context) {
    if (!defined(this._pickId)) {
      this._pickId = context.createPickId({
        primitive: this._pickPrimitive,
        collection: this._collection,
        id: this._id,
      });
    }

    return this._pickId;
  };

  Billboard.prototype._updateClamping = function () {
    Billboard._updateClamping(this._billboardCollection, this);
  };

  var scratchCartographic$4 = new Cartographic();
  var scratchPosition$8 = new Cartesian3();

  Billboard._updateClamping = function (collection, owner) {
    var scene = collection._scene;
    if (!defined(scene) || !defined(scene.globe)) {
      //>>includeStart('debug', pragmas.debug);
      if (owner._heightReference !== HeightReference$1.NONE) {
        throw new DeveloperError(
          "Height reference is not supported without a scene and globe."
        );
      }
      //>>includeEnd('debug');
      return;
    }

    var globe = scene.globe;
    var ellipsoid = globe.ellipsoid;
    var surface = globe._surface;

    var mode = scene.frameState.mode;

    var modeChanged = mode !== owner._mode;
    owner._mode = mode;

    if (
      (owner._heightReference === HeightReference$1.NONE || modeChanged) &&
      defined(owner._removeCallbackFunc)
    ) {
      owner._removeCallbackFunc();
      owner._removeCallbackFunc = undefined;
      owner._clampedPosition = undefined;
    }

    if (
      owner._heightReference === HeightReference$1.NONE ||
      !defined(owner._position)
    ) {
      return;
    }

    var position = ellipsoid.cartesianToCartographic(owner._position);
    if (!defined(position)) {
      owner._actualClampedPosition = undefined;
      return;
    }

    if (defined(owner._removeCallbackFunc)) {
      owner._removeCallbackFunc();
    }

    function updateFunction(clampedPosition) {
      if (owner._heightReference === HeightReference$1.RELATIVE_TO_GROUND) {
        if (owner._mode === SceneMode$1.SCENE3D) {
          var clampedCart = ellipsoid.cartesianToCartographic(
            clampedPosition,
            scratchCartographic$4
          );
          clampedCart.height += position.height;
          ellipsoid.cartographicToCartesian(clampedCart, clampedPosition);
        } else {
          clampedPosition.x += position.height;
        }
      }
      owner._clampedPosition = Cartesian3.clone(
        clampedPosition,
        owner._clampedPosition
      );
    }
    owner._removeCallbackFunc = surface.updateHeight(position, updateFunction);

    Cartographic.clone(position, scratchCartographic$4);
    var height = globe.getHeight(position);
    if (defined(height)) {
      scratchCartographic$4.height = height;
    }

    ellipsoid.cartographicToCartesian(scratchCartographic$4, scratchPosition$8);

    updateFunction(scratchPosition$8);
  };

  Billboard.prototype._loadImage = function () {
    var atlas = this._billboardCollection._textureAtlas;

    var imageId = this._imageId;
    var image = this._image;
    var imageSubRegion = this._imageSubRegion;
    var imageIndexPromise;

    if (defined(image)) {
      imageIndexPromise = atlas.addImage(imageId, image);
    }
    if (defined(imageSubRegion)) {
      imageIndexPromise = atlas.addSubRegion(imageId, imageSubRegion);
    }

    this._imageIndexPromise = imageIndexPromise;

    if (!defined(imageIndexPromise)) {
      return;
    }

    var that = this;
    imageIndexPromise
      .then(function (index) {
        if (
          that._imageId !== imageId ||
          that._image !== image ||
          !BoundingRectangle.equals(that._imageSubRegion, imageSubRegion)
        ) {
          // another load occurred before this one finished, ignore the index
          return;
        }

        // fill in imageWidth and imageHeight
        var textureCoordinates = atlas.textureCoordinates[index];
        that._imageWidth = atlas.texture.width * textureCoordinates.width;
        that._imageHeight = atlas.texture.height * textureCoordinates.height;

        that._imageIndex = index;
        that._ready = true;
        that._image = undefined;
        that._imageIndexPromise = undefined;
        makeDirty(that, IMAGE_INDEX_INDEX);
      })
      .otherwise(function (error) {
        console.error("Error loading image for billboard: " + error);
        that._imageIndexPromise = undefined;
      });
  };

  /**
   * <p>
   * Sets the image to be used for this billboard.  If a texture has already been created for the
   * given id, the existing texture is used.
   * </p>
   * <p>
   * This function is useful for dynamically creating textures that are shared across many billboards.
   * Only the first billboard will actually call the function and create the texture, while subsequent
   * billboards created with the same id will simply re-use the existing texture.
   * </p>
   * <p>
   * To load an image from a URL, setting the {@link Billboard#image} property is more convenient.
   * </p>
   *
   * @param {String} id The id of the image.  This can be any string that uniquely identifies the image.
   * @param {HTMLImageElement|HTMLCanvasElement|String|Resource|Billboard.CreateImageCallback} image The image to load.  This parameter
   *        can either be a loaded Image or Canvas, a URL which will be loaded as an Image automatically,
   *        or a function which will be called to create the image if it hasn't been loaded already.
   * @example
   * // create a billboard image dynamically
   * function drawImage(id) {
   *   // create and draw an image using a canvas
   *   var canvas = document.createElement('canvas');
   *   var context2D = canvas.getContext('2d');
   *   // ... draw image
   *   return canvas;
   * }
   * // drawImage will be called to create the texture
   * b.setImage('myImage', drawImage);
   *
   * // subsequent billboards created in the same collection using the same id will use the existing
   * // texture, without the need to create the canvas or draw the image
   * b2.setImage('myImage', drawImage);
   */
  Billboard.prototype.setImage = function (id, image) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required.");
    }
    if (!defined(image)) {
      throw new DeveloperError("image is required.");
    }
    //>>includeEnd('debug');

    if (this._imageId === id) {
      return;
    }

    this._imageIndex = -1;
    this._imageSubRegion = undefined;
    this._imageId = id;
    this._image = image;

    if (defined(this._billboardCollection._textureAtlas)) {
      this._loadImage();
    }
  };

  /**
   * Uses a sub-region of the image with the given id as the image for this billboard,
   * measured in pixels from the bottom-left.
   *
   * @param {String} id The id of the image to use.
   * @param {BoundingRectangle} subRegion The sub-region of the image.
   *
   * @exception {RuntimeError} image with id must be in the atlas
   */
  Billboard.prototype.setImageSubRegion = function (id, subRegion) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required.");
    }
    if (!defined(subRegion)) {
      throw new DeveloperError("subRegion is required.");
    }
    //>>includeEnd('debug');

    if (
      this._imageId === id &&
      BoundingRectangle.equals(this._imageSubRegion, subRegion)
    ) {
      return;
    }

    this._imageIndex = -1;
    this._imageId = id;
    this._imageSubRegion = BoundingRectangle.clone(subRegion);

    if (defined(this._billboardCollection._textureAtlas)) {
      this._loadImage();
    }
  };

  Billboard.prototype._setTranslate = function (value) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(value)) {
      throw new DeveloperError("value is required.");
    }
    //>>includeEnd('debug');

    var translate = this._translate;
    if (!Cartesian2.equals(translate, value)) {
      Cartesian2.clone(value, translate);
      makeDirty(this, PIXEL_OFFSET_INDEX);
    }
  };

  Billboard.prototype._getActualPosition = function () {
    return defined(this._clampedPosition)
      ? this._clampedPosition
      : this._actualPosition;
  };

  Billboard.prototype._setActualPosition = function (value) {
    if (!defined(this._clampedPosition)) {
      Cartesian3.clone(value, this._actualPosition);
    }
    makeDirty(this, POSITION_INDEX);
  };

  var tempCartesian3 = new Cartesian4();
  Billboard._computeActualPosition = function (
    billboard,
    position,
    frameState,
    modelMatrix
  ) {
    if (defined(billboard._clampedPosition)) {
      if (frameState.mode !== billboard._mode) {
        billboard._updateClamping();
      }
      return billboard._clampedPosition;
    } else if (frameState.mode === SceneMode$1.SCENE3D) {
      return position;
    }

    Matrix4.multiplyByPoint(modelMatrix, position, tempCartesian3);
    return SceneTransforms.computeActualWgs84Position(frameState, tempCartesian3);
  };

  var scratchCartesian3$9 = new Cartesian3();

  // This function is basically a stripped-down JavaScript version of BillboardCollectionVS.glsl
  Billboard._computeScreenSpacePosition = function (
    modelMatrix,
    position,
    eyeOffset,
    pixelOffset,
    scene,
    result
  ) {
    // Model to world coordinates
    var positionWorld = Matrix4.multiplyByPoint(
      modelMatrix,
      position,
      scratchCartesian3$9
    );

    // World to window coordinates
    var positionWC = SceneTransforms.wgs84WithEyeOffsetToWindowCoordinates(
      scene,
      positionWorld,
      eyeOffset,
      result
    );
    if (!defined(positionWC)) {
      return undefined;
    }

    // Apply pixel offset
    Cartesian2.add(positionWC, pixelOffset, positionWC);

    return positionWC;
  };

  var scratchPixelOffset = new Cartesian2(0.0, 0.0);

  /**
   * Computes the screen-space position of the billboard's origin, taking into account eye and pixel offsets.
   * The screen space origin is the top, left corner of the canvas; <code>x</code> increases from
   * left to right, and <code>y</code> increases from top to bottom.
   *
   * @param {Scene} scene The scene.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The screen-space position of the billboard.
   *
   * @exception {DeveloperError} Billboard must be in a collection.
   *
   * @example
   * console.log(b.computeScreenSpacePosition(scene).toString());
   *
   * @see Billboard#eyeOffset
   * @see Billboard#pixelOffset
   */
  Billboard.prototype.computeScreenSpacePosition = function (scene, result) {
    var billboardCollection = this._billboardCollection;
    if (!defined(result)) {
      result = new Cartesian2();
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(billboardCollection)) {
      throw new DeveloperError(
        "Billboard must be in a collection.  Was it removed?"
      );
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    // pixel offset for screen space computation is the pixelOffset + screen space translate
    Cartesian2.clone(this._pixelOffset, scratchPixelOffset);
    Cartesian2.add(scratchPixelOffset, this._translate, scratchPixelOffset);

    var modelMatrix = billboardCollection.modelMatrix;
    var position = this._position;
    if (defined(this._clampedPosition)) {
      position = this._clampedPosition;
      if (scene.mode !== SceneMode$1.SCENE3D) {
        // position needs to be in world coordinates
        var projection = scene.mapProjection;
        var ellipsoid = projection.ellipsoid;
        var cart = projection.unproject(position, scratchCartographic$4);
        position = ellipsoid.cartographicToCartesian(cart, scratchCartesian3$9);
        modelMatrix = Matrix4.IDENTITY;
      }
    }

    var windowCoordinates = Billboard._computeScreenSpacePosition(
      modelMatrix,
      position,
      this._eyeOffset,
      scratchPixelOffset,
      scene,
      result
    );
    return windowCoordinates;
  };

  /**
   * Gets a billboard's screen space bounding box centered around screenSpacePosition.
   * @param {Billboard} billboard The billboard to get the screen space bounding box for.
   * @param {Cartesian2} screenSpacePosition The screen space center of the label.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The screen space bounding box.
   *
   * @private
   */
  Billboard.getScreenSpaceBoundingBox = function (
    billboard,
    screenSpacePosition,
    result
  ) {
    var width = billboard.width;
    var height = billboard.height;

    var scale = billboard.scale;
    width *= scale;
    height *= scale;

    var x = screenSpacePosition.x;
    if (billboard.horizontalOrigin === HorizontalOrigin$1.RIGHT) {
      x -= width;
    } else if (billboard.horizontalOrigin === HorizontalOrigin$1.CENTER) {
      x -= width * 0.5;
    }

    var y = screenSpacePosition.y;
    if (
      billboard.verticalOrigin === VerticalOrigin$1.BOTTOM ||
      billboard.verticalOrigin === VerticalOrigin$1.BASELINE
    ) {
      y -= height;
    } else if (billboard.verticalOrigin === VerticalOrigin$1.CENTER) {
      y -= height * 0.5;
    }

    if (!defined(result)) {
      result = new BoundingRectangle();
    }

    result.x = x;
    result.y = y;
    result.width = width;
    result.height = height;

    return result;
  };

  /**
   * Determines if this billboard equals another billboard.  Billboards are equal if all their properties
   * are equal.  Billboards in different collections can be equal.
   *
   * @param {Billboard} other The billboard to compare for equality.
   * @returns {Boolean} <code>true</code> if the billboards are equal; otherwise, <code>false</code>.
   */
  Billboard.prototype.equals = function (other) {
    return (
      this === other ||
      (defined(other) &&
        this._id === other._id &&
        Cartesian3.equals(this._position, other._position) &&
        this._imageId === other._imageId &&
        this._show === other._show &&
        this._scale === other._scale &&
        this._verticalOrigin === other._verticalOrigin &&
        this._horizontalOrigin === other._horizontalOrigin &&
        this._heightReference === other._heightReference &&
        BoundingRectangle.equals(this._imageSubRegion, other._imageSubRegion) &&
        Color.equals(this._color, other._color) &&
        Cartesian2.equals(this._pixelOffset, other._pixelOffset) &&
        Cartesian2.equals(this._translate, other._translate) &&
        Cartesian3.equals(this._eyeOffset, other._eyeOffset) &&
        NearFarScalar.equals(this._scaleByDistance, other._scaleByDistance) &&
        NearFarScalar.equals(
          this._translucencyByDistance,
          other._translucencyByDistance
        ) &&
        NearFarScalar.equals(
          this._pixelOffsetScaleByDistance,
          other._pixelOffsetScaleByDistance
        ) &&
        DistanceDisplayCondition.equals(
          this._distanceDisplayCondition,
          other._distanceDisplayCondition
        ) &&
        this._disableDepthTestDistance === other._disableDepthTestDistance)
    );
  };

  Billboard.prototype._destroy = function () {
    if (defined(this._customData)) {
      this._billboardCollection._scene.globe._surface.removeTileCustomData(
        this._customData
      );
      this._customData = undefined;
    }

    if (defined(this._removeCallbackFunc)) {
      this._removeCallbackFunc();
      this._removeCallbackFunc = undefined;
    }

    this.image = undefined;
    this._pickId = this._pickId && this._pickId.destroy();
    this._billboardCollection = undefined;
  };

  /**
   * Determines how opaque and translucent parts of billboards, points, and labels are blended with the scene.
   *
   * @enum {Number}
   */
  var BlendOption = {
    /**
     * The billboards, points, or labels in the collection are completely opaque.
     * @type {Number}
     * @constant
     */
    OPAQUE: 0,

    /**
     * The billboards, points, or labels in the collection are completely translucent.
     * @type {Number}
     * @constant
     */
    TRANSLUCENT: 1,

    /**
     * The billboards, points, or labels in the collection are both opaque and translucent.
     * @type {Number}
     * @constant
     */
    OPAQUE_AND_TRANSLUCENT: 2,
  };
  var BlendOption$1 = Object.freeze(BlendOption);

  /**
   * Settings for the generation of signed distance field glyphs
   *
   * @private
   */
  var SDFSettings = {
    /**
     * The font size in pixels
     *
     * @type {Number}
     * @constant
     */
    FONT_SIZE: 48.0,

    /**
     * Whitespace padding around glyphs.
     *
     * @type {Number}
     * @constant
     */
    PADDING: 10.0,

    /**
     * How many pixels around the glyph shape to use for encoding distance
     *
     * @type {Number}
     * @constant
     */
    RADIUS: 8.0,

    /**
     * How much of the radius (relative) is used for the inside part the glyph.
     *
     * @type {Number}
     * @constant
     */
    CUTOFF: 0.25,
  };
  var SDFSettings$1 = Object.freeze(SDFSettings);

  // The atlas is made up of regions of space called nodes that contain images or child nodes.
  function TextureAtlasNode(
    bottomLeft,
    topRight,
    childNode1,
    childNode2,
    imageIndex
  ) {
    this.bottomLeft = defaultValue(bottomLeft, Cartesian2.ZERO);
    this.topRight = defaultValue(topRight, Cartesian2.ZERO);
    this.childNode1 = childNode1;
    this.childNode2 = childNode2;
    this.imageIndex = imageIndex;
  }

  var defaultInitialSize = new Cartesian2(16.0, 16.0);

  /**
   * A TextureAtlas stores multiple images in one square texture and keeps
   * track of the texture coordinates for each image. TextureAtlas is dynamic,
   * meaning new images can be added at any point in time.
   * Texture coordinates are subject to change if the texture atlas resizes, so it is
   * important to check {@link TextureAtlas#getGUID} before using old values.
   *
   * @alias TextureAtlas
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Scene} options.context The context in which the texture gets created.
   * @param {PixelFormat} [options.pixelFormat=PixelFormat.RGBA] The pixel format of the texture.
   * @param {Number} [options.borderWidthInPixels=1] The amount of spacing between adjacent images in pixels.
   * @param {Cartesian2} [options.initialSize=new Cartesian2(16.0, 16.0)] The initial side lengths of the texture.
   *
   * @exception {DeveloperError} borderWidthInPixels must be greater than or equal to zero.
   * @exception {DeveloperError} initialSize must be greater than zero.
   *
   * @private
   */
  function TextureAtlas(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var borderWidthInPixels = defaultValue(options.borderWidthInPixels, 1.0);
    var initialSize = defaultValue(options.initialSize, defaultInitialSize);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.context)) {
      throw new DeveloperError("context is required.");
    }
    if (borderWidthInPixels < 0) {
      throw new DeveloperError(
        "borderWidthInPixels must be greater than or equal to zero."
      );
    }
    if (initialSize.x < 1 || initialSize.y < 1) {
      throw new DeveloperError("initialSize must be greater than zero.");
    }
    //>>includeEnd('debug');

    this._context = options.context;
    this._pixelFormat = defaultValue(options.pixelFormat, PixelFormat$1.RGBA);
    this._borderWidthInPixels = borderWidthInPixels;
    this._textureCoordinates = [];
    this._guid = createGuid();
    this._idHash = {};
    this._initialSize = initialSize;

    this._root = undefined;
  }

  Object.defineProperties(TextureAtlas.prototype, {
    /**
     * The amount of spacing between adjacent images in pixels.
     * @memberof TextureAtlas.prototype
     * @type {Number}
     */
    borderWidthInPixels: {
      get: function () {
        return this._borderWidthInPixels;
      },
    },

    /**
     * An array of {@link BoundingRectangle} texture coordinate regions for all the images in the texture atlas.
     * The x and y values of the rectangle correspond to the bottom-left corner of the texture coordinate.
     * The coordinates are in the order that the corresponding images were added to the atlas.
     * @memberof TextureAtlas.prototype
     * @type {BoundingRectangle[]}
     */
    textureCoordinates: {
      get: function () {
        return this._textureCoordinates;
      },
    },

    /**
     * The texture that all of the images are being written to.
     * @memberof TextureAtlas.prototype
     * @type {Texture}
     */
    texture: {
      get: function () {
        if (!defined(this._texture)) {
          this._texture = new Texture({
            context: this._context,
            width: this._initialSize.x,
            height: this._initialSize.y,
            pixelFormat: this._pixelFormat,
          });
        }
        return this._texture;
      },
    },

    /**
     * The number of images in the texture atlas. This value increases
     * every time addImage or addImages is called.
     * Texture coordinates are subject to change if the texture atlas resizes, so it is
     * important to check {@link TextureAtlas#getGUID} before using old values.
     * @memberof TextureAtlas.prototype
     * @type {Number}
     */
    numberOfImages: {
      get: function () {
        return this._textureCoordinates.length;
      },
    },

    /**
     * The atlas' globally unique identifier (GUID).
     * The GUID changes whenever the texture atlas is modified.
     * Classes that use a texture atlas should check if the GUID
     * has changed before processing the atlas data.
     * @memberof TextureAtlas.prototype
     * @type {String}
     */
    guid: {
      get: function () {
        return this._guid;
      },
    },
  });

  // Builds a larger texture and copies the old texture into the new one.
  function resizeAtlas(textureAtlas, image) {
    var context = textureAtlas._context;
    var numImages = textureAtlas.numberOfImages;
    var scalingFactor = 2.0;
    var borderWidthInPixels = textureAtlas._borderWidthInPixels;
    if (numImages > 0) {
      var oldAtlasWidth = textureAtlas._texture.width;
      var oldAtlasHeight = textureAtlas._texture.height;
      var atlasWidth =
        scalingFactor * (oldAtlasWidth + image.width + borderWidthInPixels);
      var atlasHeight =
        scalingFactor * (oldAtlasHeight + image.height + borderWidthInPixels);
      var widthRatio = oldAtlasWidth / atlasWidth;
      var heightRatio = oldAtlasHeight / atlasHeight;

      // Create new node structure, putting the old root node in the bottom left.
      var nodeBottomRight = new TextureAtlasNode(
        new Cartesian2(oldAtlasWidth + borderWidthInPixels, borderWidthInPixels),
        new Cartesian2(atlasWidth, oldAtlasHeight)
      );
      var nodeBottomHalf = new TextureAtlasNode(
        new Cartesian2(),
        new Cartesian2(atlasWidth, oldAtlasHeight),
        textureAtlas._root,
        nodeBottomRight
      );
      var nodeTopHalf = new TextureAtlasNode(
        new Cartesian2(borderWidthInPixels, oldAtlasHeight + borderWidthInPixels),
        new Cartesian2(atlasWidth, atlasHeight)
      );
      var nodeMain = new TextureAtlasNode(
        new Cartesian2(),
        new Cartesian2(atlasWidth, atlasHeight),
        nodeBottomHalf,
        nodeTopHalf
      );

      // Resize texture coordinates.
      for (var i = 0; i < textureAtlas._textureCoordinates.length; i++) {
        var texCoord = textureAtlas._textureCoordinates[i];
        if (defined(texCoord)) {
          texCoord.x *= widthRatio;
          texCoord.y *= heightRatio;
          texCoord.width *= widthRatio;
          texCoord.height *= heightRatio;
        }
      }

      // Copy larger texture.
      var newTexture = new Texture({
        context: textureAtlas._context,
        width: atlasWidth,
        height: atlasHeight,
        pixelFormat: textureAtlas._pixelFormat,
      });

      var framebuffer = new Framebuffer({
        context: context,
        colorTextures: [textureAtlas._texture],
        destroyAttachments: false,
      });

      framebuffer._bind();
      newTexture.copyFromFramebuffer(0, 0, 0, 0, atlasWidth, atlasHeight);
      framebuffer._unBind();
      framebuffer.destroy();
      textureAtlas._texture =
        textureAtlas._texture && textureAtlas._texture.destroy();
      textureAtlas._texture = newTexture;
      textureAtlas._root = nodeMain;
    } else {
      // First image exceeds initialSize
      var initialWidth = scalingFactor * (image.width + 2 * borderWidthInPixels);
      var initialHeight =
        scalingFactor * (image.height + 2 * borderWidthInPixels);
      if (initialWidth < textureAtlas._initialSize.x) {
        initialWidth = textureAtlas._initialSize.x;
      }
      if (initialHeight < textureAtlas._initialSize.y) {
        initialHeight = textureAtlas._initialSize.y;
      }
      textureAtlas._texture =
        textureAtlas._texture && textureAtlas._texture.destroy();
      textureAtlas._texture = new Texture({
        context: textureAtlas._context,
        width: initialWidth,
        height: initialHeight,
        pixelFormat: textureAtlas._pixelFormat,
      });
      textureAtlas._root = new TextureAtlasNode(
        new Cartesian2(borderWidthInPixels, borderWidthInPixels),
        new Cartesian2(initialWidth, initialHeight)
      );
    }
  }

  // A recursive function that finds the best place to insert
  // a new image based on existing image 'nodes'.
  // Inspired by: http://blackpawn.com/texts/lightmaps/default.html
  function findNode$1(textureAtlas, node, image) {
    if (!defined(node)) {
      return undefined;
    }

    // If a leaf node
    if (!defined(node.childNode1) && !defined(node.childNode2)) {
      // Node already contains an image, don't add to it.
      if (defined(node.imageIndex)) {
        return undefined;
      }

      var nodeWidth = node.topRight.x - node.bottomLeft.x;
      var nodeHeight = node.topRight.y - node.bottomLeft.y;
      var widthDifference = nodeWidth - image.width;
      var heightDifference = nodeHeight - image.height;

      // Node is smaller than the image.
      if (widthDifference < 0 || heightDifference < 0) {
        return undefined;
      }

      // If the node is the same size as the image, return the node
      if (widthDifference === 0 && heightDifference === 0) {
        return node;
      }

      // Vertical split (childNode1 = left half, childNode2 = right half).
      if (widthDifference > heightDifference) {
        node.childNode1 = new TextureAtlasNode(
          new Cartesian2(node.bottomLeft.x, node.bottomLeft.y),
          new Cartesian2(node.bottomLeft.x + image.width, node.topRight.y)
        );
        // Only make a second child if the border gives enough space.
        var childNode2BottomLeftX =
          node.bottomLeft.x + image.width + textureAtlas._borderWidthInPixels;
        if (childNode2BottomLeftX < node.topRight.x) {
          node.childNode2 = new TextureAtlasNode(
            new Cartesian2(childNode2BottomLeftX, node.bottomLeft.y),
            new Cartesian2(node.topRight.x, node.topRight.y)
          );
        }
      }
      // Horizontal split (childNode1 = bottom half, childNode2 = top half).
      else {
        node.childNode1 = new TextureAtlasNode(
          new Cartesian2(node.bottomLeft.x, node.bottomLeft.y),
          new Cartesian2(node.topRight.x, node.bottomLeft.y + image.height)
        );
        // Only make a second child if the border gives enough space.
        var childNode2BottomLeftY =
          node.bottomLeft.y + image.height + textureAtlas._borderWidthInPixels;
        if (childNode2BottomLeftY < node.topRight.y) {
          node.childNode2 = new TextureAtlasNode(
            new Cartesian2(node.bottomLeft.x, childNode2BottomLeftY),
            new Cartesian2(node.topRight.x, node.topRight.y)
          );
        }
      }
      return findNode$1(textureAtlas, node.childNode1, image);
    }

    // If not a leaf node
    return (
      findNode$1(textureAtlas, node.childNode1, image) ||
      findNode$1(textureAtlas, node.childNode2, image)
    );
  }

  // Adds image of given index to the texture atlas. Called from addImage and addImages.
  function addImage(textureAtlas, image, index) {
    var node = findNode$1(textureAtlas, textureAtlas._root, image);
    if (defined(node)) {
      // Found a node that can hold the image.
      node.imageIndex = index;

      // Add texture coordinate and write to texture
      var atlasWidth = textureAtlas._texture.width;
      var atlasHeight = textureAtlas._texture.height;
      var nodeWidth = node.topRight.x - node.bottomLeft.x;
      var nodeHeight = node.topRight.y - node.bottomLeft.y;
      var x = node.bottomLeft.x / atlasWidth;
      var y = node.bottomLeft.y / atlasHeight;
      var w = nodeWidth / atlasWidth;
      var h = nodeHeight / atlasHeight;
      textureAtlas._textureCoordinates[index] = new BoundingRectangle(x, y, w, h);
      textureAtlas._texture.copyFrom(image, node.bottomLeft.x, node.bottomLeft.y);
    } else {
      // No node found, must resize the texture atlas.
      resizeAtlas(textureAtlas, image);
      addImage(textureAtlas, image, index);
    }

    textureAtlas._guid = createGuid();
  }

  /**
   * Adds an image to the atlas.  If the image is already in the atlas, the atlas is unchanged and
   * the existing index is used.
   *
   * @param {String} id An identifier to detect whether the image already exists in the atlas.
   * @param {HTMLImageElement|HTMLCanvasElement|String|Resource|Promise|TextureAtlas.CreateImageCallback} image An image or canvas to add to the texture atlas,
   *        or a URL to an Image, or a Promise for an image, or a function that creates an image.
   * @returns {Promise.<Number>} A Promise for the image index.
   */
  TextureAtlas.prototype.addImage = function (id, image) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required.");
    }
    if (!defined(image)) {
      throw new DeveloperError("image is required.");
    }
    //>>includeEnd('debug');

    var indexPromise = this._idHash[id];
    if (defined(indexPromise)) {
      // we're already aware of this source
      return indexPromise;
    }

    // not in atlas, create the promise for the index

    if (typeof image === "function") {
      // if image is a function, call it
      image = image(id);
      //>>includeStart('debug', pragmas.debug);
      if (!defined(image)) {
        throw new DeveloperError("image is required.");
      }
      //>>includeEnd('debug');
    } else if (typeof image === "string" || image instanceof Resource) {
      // Get a resource
      var resource = Resource.createIfNeeded(image);
      image = resource.fetchImage();
    }

    var that = this;

    indexPromise = when(image, function (image) {
      if (that.isDestroyed()) {
        return -1;
      }

      var index = that.numberOfImages;

      addImage(that, image, index);

      return index;
    });

    // store the promise
    this._idHash[id] = indexPromise;

    return indexPromise;
  };

  /**
   * Add a sub-region of an existing atlas image as additional image indices.
   *
   * @param {String} id The identifier of the existing image.
   * @param {BoundingRectangle} subRegion An {@link BoundingRectangle} sub-region measured in pixels from the bottom-left.
   *
   * @returns {Promise.<Number>} A Promise for the image index.
   */
  TextureAtlas.prototype.addSubRegion = function (id, subRegion) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required.");
    }
    if (!defined(subRegion)) {
      throw new DeveloperError("subRegion is required.");
    }
    //>>includeEnd('debug');

    var indexPromise = this._idHash[id];
    if (!defined(indexPromise)) {
      throw new RuntimeError(
        'image with id "' + id + '" not found in the atlas.'
      );
    }

    var that = this;
    return when(indexPromise, function (index) {
      if (index === -1) {
        // the atlas is destroyed
        return -1;
      }
      var atlasWidth = that._texture.width;
      var atlasHeight = that._texture.height;
      var numImages = that.numberOfImages;

      var baseRegion = that._textureCoordinates[index];
      var x = baseRegion.x + subRegion.x / atlasWidth;
      var y = baseRegion.y + subRegion.y / atlasHeight;
      var w = subRegion.width / atlasWidth;
      var h = subRegion.height / atlasHeight;
      that._textureCoordinates.push(new BoundingRectangle(x, y, w, h));
      that._guid = createGuid();

      return numImages;
    });
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see TextureAtlas#destroy
   */
  TextureAtlas.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * atlas = atlas && atlas.destroy();
   *
   * @see TextureAtlas#isDestroyed
   */
  TextureAtlas.prototype.destroy = function () {
    this._texture = this._texture && this._texture.destroy();
    return destroyObject(this);
  };

  var SHOW_INDEX$1 = Billboard.SHOW_INDEX;
  var POSITION_INDEX$1 = Billboard.POSITION_INDEX;
  var PIXEL_OFFSET_INDEX$1 = Billboard.PIXEL_OFFSET_INDEX;
  var EYE_OFFSET_INDEX$1 = Billboard.EYE_OFFSET_INDEX;
  var HORIZONTAL_ORIGIN_INDEX$1 = Billboard.HORIZONTAL_ORIGIN_INDEX;
  var VERTICAL_ORIGIN_INDEX$1 = Billboard.VERTICAL_ORIGIN_INDEX;
  var SCALE_INDEX$1 = Billboard.SCALE_INDEX;
  var IMAGE_INDEX_INDEX$1 = Billboard.IMAGE_INDEX_INDEX;
  var COLOR_INDEX$1 = Billboard.COLOR_INDEX;
  var ROTATION_INDEX$1 = Billboard.ROTATION_INDEX;
  var ALIGNED_AXIS_INDEX$1 = Billboard.ALIGNED_AXIS_INDEX;
  var SCALE_BY_DISTANCE_INDEX$1 = Billboard.SCALE_BY_DISTANCE_INDEX;
  var TRANSLUCENCY_BY_DISTANCE_INDEX$1 = Billboard.TRANSLUCENCY_BY_DISTANCE_INDEX;
  var PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX$1 =
    Billboard.PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX;
  var DISTANCE_DISPLAY_CONDITION_INDEX = Billboard.DISTANCE_DISPLAY_CONDITION;
  var DISABLE_DEPTH_DISTANCE$1 = Billboard.DISABLE_DEPTH_DISTANCE;
  var TEXTURE_COORDINATE_BOUNDS = Billboard.TEXTURE_COORDINATE_BOUNDS;
  var SDF_INDEX$1 = Billboard.SDF_INDEX;
  var NUMBER_OF_PROPERTIES = Billboard.NUMBER_OF_PROPERTIES;

  var attributeLocations;

  var attributeLocationsBatched = {
    positionHighAndScale: 0,
    positionLowAndRotation: 1,
    compressedAttribute0: 2, // pixel offset, translate, horizontal origin, vertical origin, show, direction, texture coordinates
    compressedAttribute1: 3, // aligned axis, translucency by distance, image width
    compressedAttribute2: 4, // image height, color, pick color, size in meters, valid aligned axis, 13 bits free
    eyeOffset: 5, // 4 bytes free
    scaleByDistance: 6,
    pixelOffsetScaleByDistance: 7,
    compressedAttribute3: 8,
    textureCoordinateBoundsOrLabelTranslate: 9,
    a_batchId: 10,
    sdf: 11,
  };

  var attributeLocationsInstanced = {
    direction: 0,
    positionHighAndScale: 1,
    positionLowAndRotation: 2, // texture offset in w
    compressedAttribute0: 3,
    compressedAttribute1: 4,
    compressedAttribute2: 5,
    eyeOffset: 6, // texture range in w
    scaleByDistance: 7,
    pixelOffsetScaleByDistance: 8,
    compressedAttribute3: 9,
    textureCoordinateBoundsOrLabelTranslate: 10,
    a_batchId: 11,
    sdf: 12,
  };

  /**
   * A renderable collection of billboards.  Billboards are viewport-aligned
   * images positioned in the 3D scene.
   * <br /><br />
   * <div align='center'>
   * <img src='Images/Billboard.png' width='400' height='300' /><br />
   * Example billboards
   * </div>
   * <br /><br />
   * Billboards are added and removed from the collection using {@link BillboardCollection#add}
   * and {@link BillboardCollection#remove}.  Billboards in a collection automatically share textures
   * for images with the same identifier.
   *
   * @alias BillboardCollection
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms each billboard from model to world coordinates.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {Scene} [options.scene] Must be passed in for billboards that use the height reference property or will be depth tested against the globe.
   * @param {BlendOption} [options.blendOption=BlendOption.OPAQUE_AND_TRANSLUCENT] The billboard blending option. The default
   * is used for rendering both opaque and translucent billboards. However, if either all of the billboards are completely opaque or all are completely translucent,
   * setting the technique to BlendOption.OPAQUE or BlendOption.TRANSLUCENT can improve performance by up to 2x.
   *
   * @performance For best performance, prefer a few collections, each with many billboards, to
   * many collections with only a few billboards each.  Organize collections so that billboards
   * with the same update frequency are in the same collection, i.e., billboards that do not
   * change should be in one collection; billboards that change every frame should be in another
   * collection; and so on.
   *
   * @see BillboardCollection#add
   * @see BillboardCollection#remove
   * @see Billboard
   * @see LabelCollection
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Billboards.html|Cesium Sandcastle Billboard Demo}
   *
   * @example
   * // Create a billboard collection with two billboards
   * var billboards = scene.primitives.add(new Cesium.BillboardCollection());
   * billboards.add({
   *   position : new Cesium.Cartesian3(1.0, 2.0, 3.0),
   *   image : 'url/to/image'
   * });
   * billboards.add({
   *   position : new Cesium.Cartesian3(4.0, 5.0, 6.0),
   *   image : 'url/to/another/image'
   * });
   */
  function BillboardCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._scene = options.scene;
    this._batchTable = options.batchTable;

    this._textureAtlas = undefined;
    this._textureAtlasGUID = undefined;
    this._destroyTextureAtlas = true;
    this._sp = undefined;
    this._spTranslucent = undefined;
    this._rsOpaque = undefined;
    this._rsTranslucent = undefined;
    this._vaf = undefined;

    this._billboards = [];
    this._billboardsToUpdate = [];
    this._billboardsToUpdateIndex = 0;
    this._billboardsRemoved = false;
    this._createVertexArray = false;

    this._shaderRotation = false;
    this._compiledShaderRotation = false;

    this._shaderAlignedAxis = false;
    this._compiledShaderAlignedAxis = false;

    this._shaderScaleByDistance = false;
    this._compiledShaderScaleByDistance = false;

    this._shaderTranslucencyByDistance = false;
    this._compiledShaderTranslucencyByDistance = false;

    this._shaderPixelOffsetScaleByDistance = false;
    this._compiledShaderPixelOffsetScaleByDistance = false;

    this._shaderDistanceDisplayCondition = false;
    this._compiledShaderDistanceDisplayCondition = false;

    this._shaderDisableDepthDistance = false;
    this._compiledShaderDisableDepthDistance = false;

    this._shaderClampToGround = false;
    this._compiledShaderClampToGround = false;

    this._propertiesChanged = new Uint32Array(NUMBER_OF_PROPERTIES);

    this._maxSize = 0.0;
    this._maxEyeOffset = 0.0;
    this._maxScale = 1.0;
    this._maxPixelOffset = 0.0;
    this._allHorizontalCenter = true;
    this._allVerticalCenter = true;
    this._allSizedInMeters = true;

    this._baseVolume = new BoundingSphere();
    this._baseVolumeWC = new BoundingSphere();
    this._baseVolume2D = new BoundingSphere();
    this._boundingVolume = new BoundingSphere();
    this._boundingVolumeDirty = false;

    this._colorCommands = [];

    /**
     * The 4x4 transformation matrix that transforms each billboard in this collection from model to world coordinates.
     * When this is the identity matrix, the billboards are drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type {Matrix4}
     * @default {@link Matrix4.IDENTITY}
     *
     *
     * @example
     * var center = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
     * billboards.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(center);
     * billboards.add({
     *   image : 'url/to/image',
     *   position : new Cesium.Cartesian3(0.0, 0.0, 0.0) // center
     * });
     * billboards.add({
     *   image : 'url/to/image',
     *   position : new Cesium.Cartesian3(1000000.0, 0.0, 0.0) // east
     * });
     * billboards.add({
     *   image : 'url/to/image',
     *   position : new Cesium.Cartesian3(0.0, 1000000.0, 0.0) // north
     * });
     * billboards.add({
     *   image : 'url/to/image',
     *   position : new Cesium.Cartesian3(0.0, 0.0, 1000000.0) // up
     * });
     *
     * @see Transforms.eastNorthUpToFixedFrame
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = Matrix4.clone(Matrix4.IDENTITY);

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the texture atlas for this BillboardCollection as a fullscreen quad.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowTextureAtlas = defaultValue(
      options.debugShowTextureAtlas,
      false
    );

    /**
     * The billboard blending option. The default is used for rendering both opaque and translucent billboards.
     * However, if either all of the billboards are completely opaque or all are completely translucent,
     * setting the technique to BlendOption.OPAQUE or BlendOption.TRANSLUCENT can improve
     * performance by up to 2x.
     * @type {BlendOption}
     * @default BlendOption.OPAQUE_AND_TRANSLUCENT
     */
    this.blendOption = defaultValue(
      options.blendOption,
      BlendOption$1.OPAQUE_AND_TRANSLUCENT
    );
    this._blendOption = undefined;

    this._mode = SceneMode$1.SCENE3D;

    // The buffer usage for each attribute is determined based on the usage of the attribute over time.
    this._buffersUsage = [
      BufferUsage$1.STATIC_DRAW, // SHOW_INDEX
      BufferUsage$1.STATIC_DRAW, // POSITION_INDEX
      BufferUsage$1.STATIC_DRAW, // PIXEL_OFFSET_INDEX
      BufferUsage$1.STATIC_DRAW, // EYE_OFFSET_INDEX
      BufferUsage$1.STATIC_DRAW, // HORIZONTAL_ORIGIN_INDEX
      BufferUsage$1.STATIC_DRAW, // VERTICAL_ORIGIN_INDEX
      BufferUsage$1.STATIC_DRAW, // SCALE_INDEX
      BufferUsage$1.STATIC_DRAW, // IMAGE_INDEX_INDEX
      BufferUsage$1.STATIC_DRAW, // COLOR_INDEX
      BufferUsage$1.STATIC_DRAW, // ROTATION_INDEX
      BufferUsage$1.STATIC_DRAW, // ALIGNED_AXIS_INDEX
      BufferUsage$1.STATIC_DRAW, // SCALE_BY_DISTANCE_INDEX
      BufferUsage$1.STATIC_DRAW, // TRANSLUCENCY_BY_DISTANCE_INDEX
      BufferUsage$1.STATIC_DRAW, // PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX
      BufferUsage$1.STATIC_DRAW, // DISTANCE_DISPLAY_CONDITION_INDEX
      BufferUsage$1.STATIC_DRAW, // TEXTURE_COORDINATE_BOUNDS
    ];

    this._highlightColor = Color.clone(Color.WHITE); // Only used by Vector3DTilePoints

    var that = this;
    this._uniforms = {
      u_atlas: function () {
        return that._textureAtlas.texture;
      },
      u_highlightColor: function () {
        return that._highlightColor;
      },
    };

    var scene = this._scene;
    if (defined(scene) && defined(scene.terrainProviderChanged)) {
      this._removeCallbackFunc = scene.terrainProviderChanged.addEventListener(
        function () {
          var billboards = this._billboards;
          var length = billboards.length;
          for (var i = 0; i < length; ++i) {
            if (defined(billboards[i])) {
              billboards[i]._updateClamping();
            }
          }
        },
        this
      );
    }
  }

  Object.defineProperties(BillboardCollection.prototype, {
    /**
     * Returns the number of billboards in this collection.  This is commonly used with
     * {@link BillboardCollection#get} to iterate over all the billboards
     * in the collection.
     * @memberof BillboardCollection.prototype
     * @type {Number}
     */
    length: {
      get: function () {
        removeBillboards(this);
        return this._billboards.length;
      },
    },

    /**
     * Gets or sets the textureAtlas.
     * @memberof BillboardCollection.prototype
     * @type {TextureAtlas}
     * @private
     */
    textureAtlas: {
      get: function () {
        return this._textureAtlas;
      },
      set: function (value) {
        if (this._textureAtlas !== value) {
          this._textureAtlas =
            this._destroyTextureAtlas &&
            this._textureAtlas &&
            this._textureAtlas.destroy();
          this._textureAtlas = value;
          this._createVertexArray = true; // New per-billboard texture coordinates
        }
      },
    },

    /**
     * Gets or sets a value which determines if the texture atlas is
     * destroyed when the collection is destroyed.
     *
     * If the texture atlas is used by more than one collection, set this to <code>false</code>,
     * and explicitly destroy the atlas to avoid attempting to destroy it multiple times.
     *
     * @memberof BillboardCollection.prototype
     * @type {Boolean}
     * @private
     *
     * @example
     * // Set destroyTextureAtlas
     * // Destroy a billboard collection but not its texture atlas.
     *
     * var atlas = new TextureAtlas({
     *   scene : scene,
     *   images : images
     * });
     * billboards.textureAtlas = atlas;
     * billboards.destroyTextureAtlas = false;
     * billboards = billboards.destroy();
     * console.log(atlas.isDestroyed()); // False
     */
    destroyTextureAtlas: {
      get: function () {
        return this._destroyTextureAtlas;
      },
      set: function (value) {
        this._destroyTextureAtlas = value;
      },
    },
  });

  function destroyBillboards(billboards) {
    var length = billboards.length;
    for (var i = 0; i < length; ++i) {
      if (billboards[i]) {
        billboards[i]._destroy();
      }
    }
  }

  /**
   * Creates and adds a billboard with the specified initial properties to the collection.
   * The added billboard is returned so it can be modified or removed from the collection later.
   *
   * @param {Object}[options] A template describing the billboard's properties as shown in Example 1.
   * @returns {Billboard} The billboard that was added to the collection.
   *
   * @performance Calling <code>add</code> is expected constant time.  However, the collection's vertex buffer
   * is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.  For
   * best performance, add as many billboards as possible before calling <code>update</code>.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Example 1:  Add a billboard, specifying all the default values.
   * var b = billboards.add({
   *   show : true,
   *   position : Cesium.Cartesian3.ZERO,
   *   pixelOffset : Cesium.Cartesian2.ZERO,
   *   eyeOffset : Cesium.Cartesian3.ZERO,
   *   heightReference : Cesium.HeightReference.NONE,
   *   horizontalOrigin : Cesium.HorizontalOrigin.CENTER,
   *   verticalOrigin : Cesium.VerticalOrigin.CENTER,
   *   scale : 1.0,
   *   image : 'url/to/image',
   *   imageSubRegion : undefined,
   *   color : Cesium.Color.WHITE,
   *   id : undefined,
   *   rotation : 0.0,
   *   alignedAxis : Cesium.Cartesian3.ZERO,
   *   width : undefined,
   *   height : undefined,
   *   scaleByDistance : undefined,
   *   translucencyByDistance : undefined,
   *   pixelOffsetScaleByDistance : undefined,
   *   sizeInMeters : false,
   *   distanceDisplayCondition : undefined
   * });
   *
   * @example
   * // Example 2:  Specify only the billboard's cartographic position.
   * var b = billboards.add({
   *   position : Cesium.Cartesian3.fromDegrees(longitude, latitude, height)
   * });
   *
   * @see BillboardCollection#remove
   * @see BillboardCollection#removeAll
   */
  BillboardCollection.prototype.add = function (options) {
    var b = new Billboard(options, this);
    b._index = this._billboards.length;

    this._billboards.push(b);
    this._createVertexArray = true;

    return b;
  };

  /**
   * Removes a billboard from the collection.
   *
   * @param {Billboard} billboard The billboard to remove.
   * @returns {Boolean} <code>true</code> if the billboard was removed; <code>false</code> if the billboard was not found in the collection.
   *
   * @performance Calling <code>remove</code> is expected constant time.  However, the collection's vertex buffer
   * is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.  For
   * best performance, remove as many billboards as possible before calling <code>update</code>.
   * If you intend to temporarily hide a billboard, it is usually more efficient to call
   * {@link Billboard#show} instead of removing and re-adding the billboard.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * var b = billboards.add(...);
   * billboards.remove(b);  // Returns true
   *
   * @see BillboardCollection#add
   * @see BillboardCollection#removeAll
   * @see Billboard#show
   */
  BillboardCollection.prototype.remove = function (billboard) {
    if (this.contains(billboard)) {
      this._billboards[billboard._index] = null; // Removed later
      this._billboardsRemoved = true;
      this._createVertexArray = true;
      billboard._destroy();
      return true;
    }

    return false;
  };

  /**
   * Removes all billboards from the collection.
   *
   * @performance <code>O(n)</code>.  It is more efficient to remove all the billboards
   * from a collection and then add new ones than to create a new collection entirely.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * billboards.add(...);
   * billboards.add(...);
   * billboards.removeAll();
   *
   * @see BillboardCollection#add
   * @see BillboardCollection#remove
   */
  BillboardCollection.prototype.removeAll = function () {
    destroyBillboards(this._billboards);
    this._billboards = [];
    this._billboardsToUpdate = [];
    this._billboardsToUpdateIndex = 0;
    this._billboardsRemoved = false;

    this._createVertexArray = true;
  };

  function removeBillboards(billboardCollection) {
    if (billboardCollection._billboardsRemoved) {
      billboardCollection._billboardsRemoved = false;

      var newBillboards = [];
      var billboards = billboardCollection._billboards;
      var length = billboards.length;
      for (var i = 0, j = 0; i < length; ++i) {
        var billboard = billboards[i];
        if (billboard) {
          billboard._index = j++;
          newBillboards.push(billboard);
        }
      }

      billboardCollection._billboards = newBillboards;
    }
  }

  BillboardCollection.prototype._updateBillboard = function (
    billboard,
    propertyChanged
  ) {
    if (!billboard._dirty) {
      this._billboardsToUpdate[this._billboardsToUpdateIndex++] = billboard;
    }

    ++this._propertiesChanged[propertyChanged];
  };

  /**
   * Check whether this collection contains a given billboard.
   *
   * @param {Billboard} [billboard] The billboard to check for.
   * @returns {Boolean} true if this collection contains the billboard, false otherwise.
   *
   * @see BillboardCollection#get
   */
  BillboardCollection.prototype.contains = function (billboard) {
    return defined(billboard) && billboard._billboardCollection === this;
  };

  /**
   * Returns the billboard in the collection at the specified index.  Indices are zero-based
   * and increase as billboards are added.  Removing a billboard shifts all billboards after
   * it to the left, changing their indices.  This function is commonly used with
   * {@link BillboardCollection#length} to iterate over all the billboards
   * in the collection.
   *
   * @param {Number} index The zero-based index of the billboard.
   * @returns {Billboard} The billboard at the specified index.
   *
   * @performance Expected constant time.  If billboards were removed from the collection and
   * {@link BillboardCollection#update} was not called, an implicit <code>O(n)</code>
   * operation is performed.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Toggle the show property of every billboard in the collection
   * var len = billboards.length;
   * for (var i = 0; i < len; ++i) {
   *   var b = billboards.get(i);
   *   b.show = !b.show;
   * }
   *
   * @see BillboardCollection#length
   */
  BillboardCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    removeBillboards(this);
    return this._billboards[index];
  };

  var getIndexBuffer;

  function getIndexBufferBatched(context) {
    var sixteenK = 16 * 1024;

    var indexBuffer = context.cache.billboardCollection_indexBufferBatched;
    if (defined(indexBuffer)) {
      return indexBuffer;
    }

    // Subtract 6 because the last index is reserverd for primitive restart.
    // https://www.khronos.org/registry/webgl/specs/latest/2.0/#5.18
    var length = sixteenK * 6 - 6;
    var indices = new Uint16Array(length);
    for (var i = 0, j = 0; i < length; i += 6, j += 4) {
      indices[i] = j;
      indices[i + 1] = j + 1;
      indices[i + 2] = j + 2;

      indices[i + 3] = j + 0;
      indices[i + 4] = j + 2;
      indices[i + 5] = j + 3;
    }

    // PERFORMANCE_IDEA:  Should we reference count billboard collections, and eventually delete this?
    // Is this too much memory to allocate up front?  Should we dynamically grow it?
    indexBuffer = Buffer$1.createIndexBuffer({
      context: context,
      typedArray: indices,
      usage: BufferUsage$1.STATIC_DRAW,
      indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
    });
    indexBuffer.vertexArrayDestroyable = false;
    context.cache.billboardCollection_indexBufferBatched = indexBuffer;
    return indexBuffer;
  }

  function getIndexBufferInstanced(context) {
    var indexBuffer = context.cache.billboardCollection_indexBufferInstanced;
    if (defined(indexBuffer)) {
      return indexBuffer;
    }

    indexBuffer = Buffer$1.createIndexBuffer({
      context: context,
      typedArray: new Uint16Array([0, 1, 2, 0, 2, 3]),
      usage: BufferUsage$1.STATIC_DRAW,
      indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
    });

    indexBuffer.vertexArrayDestroyable = false;
    context.cache.billboardCollection_indexBufferInstanced = indexBuffer;
    return indexBuffer;
  }

  function getVertexBufferInstanced(context) {
    var vertexBuffer = context.cache.billboardCollection_vertexBufferInstanced;
    if (defined(vertexBuffer)) {
      return vertexBuffer;
    }

    vertexBuffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: new Float32Array([0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0]),
      usage: BufferUsage$1.STATIC_DRAW,
    });

    vertexBuffer.vertexArrayDestroyable = false;
    context.cache.billboardCollection_vertexBufferInstanced = vertexBuffer;
    return vertexBuffer;
  }

  BillboardCollection.prototype.computeNewBuffersUsage = function () {
    var buffersUsage = this._buffersUsage;
    var usageChanged = false;

    var properties = this._propertiesChanged;
    for (var k = 0; k < NUMBER_OF_PROPERTIES; ++k) {
      var newUsage =
        properties[k] === 0 ? BufferUsage$1.STATIC_DRAW : BufferUsage$1.STREAM_DRAW;
      usageChanged = usageChanged || buffersUsage[k] !== newUsage;
      buffersUsage[k] = newUsage;
    }

    return usageChanged;
  };

  function createVAF(
    context,
    numberOfBillboards,
    buffersUsage,
    instanced,
    batchTable,
    sdf
  ) {
    var attributes = [
      {
        index: attributeLocations.positionHighAndScale,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[POSITION_INDEX$1],
      },
      {
        index: attributeLocations.positionLowAndRotation,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[POSITION_INDEX$1],
      },
      {
        index: attributeLocations.compressedAttribute0,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[PIXEL_OFFSET_INDEX$1],
      },
      {
        index: attributeLocations.compressedAttribute1,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[TRANSLUCENCY_BY_DISTANCE_INDEX$1],
      },
      {
        index: attributeLocations.compressedAttribute2,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[COLOR_INDEX$1],
      },
      {
        index: attributeLocations.eyeOffset,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[EYE_OFFSET_INDEX$1],
      },
      {
        index: attributeLocations.scaleByDistance,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[SCALE_BY_DISTANCE_INDEX$1],
      },
      {
        index: attributeLocations.pixelOffsetScaleByDistance,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX$1],
      },
      {
        index: attributeLocations.compressedAttribute3,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[DISTANCE_DISPLAY_CONDITION_INDEX],
      },
      {
        index: attributeLocations.textureCoordinateBoundsOrLabelTranslate,
        componentsPerAttribute: 4,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[TEXTURE_COORDINATE_BOUNDS],
      },
    ];

    // Instancing requires one non-instanced attribute.
    if (instanced) {
      attributes.push({
        index: attributeLocations.direction,
        componentsPerAttribute: 2,
        componentDatatype: ComponentDatatype$1.FLOAT,
        vertexBuffer: getVertexBufferInstanced(context),
      });
    }

    if (defined(batchTable)) {
      attributes.push({
        index: attributeLocations.a_batchId,
        componentsPerAttribute: 1,
        componentDatatype: ComponentDatatype$1.FLOAT,
        bufferUsage: BufferUsage$1.STATIC_DRAW,
      });
    }

    if (sdf) {
      attributes.push({
        index: attributeLocations.sdf,
        componentsPerAttribute: 2,
        componentDatatype: ComponentDatatype$1.FLOAT,
        usage: buffersUsage[SDF_INDEX$1],
      });
    }

    // When instancing is enabled, only one vertex is needed for each billboard.
    var sizeInVertices = instanced ? numberOfBillboards : 4 * numberOfBillboards;
    return new VertexArrayFacade(context, attributes, sizeInVertices, instanced);
  }

  ///////////////////////////////////////////////////////////////////////////

  // Four vertices per billboard.  Each has the same position, etc., but a different screen-space direction vector.

  // PERFORMANCE_IDEA:  Save memory if a property is the same for all billboards, use a latched attribute state,
  // instead of storing it in a vertex buffer.

  var writePositionScratch = new EncodedCartesian3();

  function writePositionScaleAndRotation(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var positionHighWriter = vafWriters[attributeLocations.positionHighAndScale];
    var positionLowWriter = vafWriters[attributeLocations.positionLowAndRotation];
    var position = billboard._getActualPosition();

    if (billboardCollection._mode === SceneMode$1.SCENE3D) {
      BoundingSphere.expand(
        billboardCollection._baseVolume,
        position,
        billboardCollection._baseVolume
      );
      billboardCollection._boundingVolumeDirty = true;
    }

    EncodedCartesian3.fromCartesian(position, writePositionScratch);
    var scale = billboard.scale;
    var rotation = billboard.rotation;

    if (rotation !== 0.0) {
      billboardCollection._shaderRotation = true;
    }

    billboardCollection._maxScale = Math.max(
      billboardCollection._maxScale,
      scale
    );

    var high = writePositionScratch.high;
    var low = writePositionScratch.low;

    if (billboardCollection._instanced) {
      i = billboard._index;
      positionHighWriter(i, high.x, high.y, high.z, scale);
      positionLowWriter(i, low.x, low.y, low.z, rotation);
    } else {
      i = billboard._index * 4;
      positionHighWriter(i + 0, high.x, high.y, high.z, scale);
      positionHighWriter(i + 1, high.x, high.y, high.z, scale);
      positionHighWriter(i + 2, high.x, high.y, high.z, scale);
      positionHighWriter(i + 3, high.x, high.y, high.z, scale);

      positionLowWriter(i + 0, low.x, low.y, low.z, rotation);
      positionLowWriter(i + 1, low.x, low.y, low.z, rotation);
      positionLowWriter(i + 2, low.x, low.y, low.z, rotation);
      positionLowWriter(i + 3, low.x, low.y, low.z, rotation);
    }
  }

  var scratchCartesian2$8 = new Cartesian2();

  var UPPER_BOUND = 32768.0; // 2^15

  var LEFT_SHIFT16 = 65536.0; // 2^16
  var LEFT_SHIFT12 = 4096.0; // 2^12
  var LEFT_SHIFT8 = 256.0; // 2^8
  var LEFT_SHIFT7 = 128.0;
  var LEFT_SHIFT5 = 32.0;
  var LEFT_SHIFT3 = 8.0;
  var LEFT_SHIFT2 = 4.0;

  var RIGHT_SHIFT8 = 1.0 / 256.0;

  var LOWER_LEFT = 0.0;
  var LOWER_RIGHT = 2.0;
  var UPPER_RIGHT = 3.0;
  var UPPER_LEFT = 1.0;

  function writeCompressedAttrib0(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.compressedAttribute0];
    var pixelOffset = billboard.pixelOffset;
    var pixelOffsetX = pixelOffset.x;
    var pixelOffsetY = pixelOffset.y;

    var translate = billboard._translate;
    var translateX = translate.x;
    var translateY = translate.y;

    billboardCollection._maxPixelOffset = Math.max(
      billboardCollection._maxPixelOffset,
      Math.abs(pixelOffsetX + translateX),
      Math.abs(-pixelOffsetY + translateY)
    );

    var horizontalOrigin = billboard.horizontalOrigin;
    var verticalOrigin = billboard._verticalOrigin;
    var show = billboard.show && billboard.clusterShow;

    // If the color alpha is zero, do not show this billboard.  This lets us avoid providing
    // color during the pick pass and also eliminates a discard in the fragment shader.
    if (billboard.color.alpha === 0.0) {
      show = false;
    }

    // Raw billboards don't distinguish between BASELINE and BOTTOM, only LabelCollection does that.
    if (verticalOrigin === VerticalOrigin$1.BASELINE) {
      verticalOrigin = VerticalOrigin$1.BOTTOM;
    }

    billboardCollection._allHorizontalCenter =
      billboardCollection._allHorizontalCenter &&
      horizontalOrigin === HorizontalOrigin$1.CENTER;
    billboardCollection._allVerticalCenter =
      billboardCollection._allVerticalCenter &&
      verticalOrigin === VerticalOrigin$1.CENTER;

    var bottomLeftX = 0;
    var bottomLeftY = 0;
    var width = 0;
    var height = 0;
    var index = billboard._imageIndex;
    if (index !== -1) {
      var imageRectangle = textureAtlasCoordinates[index];

      //>>includeStart('debug', pragmas.debug);
      if (!defined(imageRectangle)) {
        throw new DeveloperError("Invalid billboard image index: " + index);
      }
      //>>includeEnd('debug');

      bottomLeftX = imageRectangle.x;
      bottomLeftY = imageRectangle.y;
      width = imageRectangle.width;
      height = imageRectangle.height;
    }
    var topRightX = bottomLeftX + width;
    var topRightY = bottomLeftY + height;

    var compressed0 =
      Math.floor(
        CesiumMath.clamp(pixelOffsetX, -UPPER_BOUND, UPPER_BOUND) + UPPER_BOUND
      ) * LEFT_SHIFT7;
    compressed0 += (horizontalOrigin + 1.0) * LEFT_SHIFT5;
    compressed0 += (verticalOrigin + 1.0) * LEFT_SHIFT3;
    compressed0 += (show ? 1.0 : 0.0) * LEFT_SHIFT2;

    var compressed1 =
      Math.floor(
        CesiumMath.clamp(pixelOffsetY, -UPPER_BOUND, UPPER_BOUND) + UPPER_BOUND
      ) * LEFT_SHIFT8;
    var compressed2 =
      Math.floor(
        CesiumMath.clamp(translateX, -UPPER_BOUND, UPPER_BOUND) + UPPER_BOUND
      ) * LEFT_SHIFT8;

    var tempTanslateY =
      (CesiumMath.clamp(translateY, -UPPER_BOUND, UPPER_BOUND) + UPPER_BOUND) *
      RIGHT_SHIFT8;
    var upperTranslateY = Math.floor(tempTanslateY);
    var lowerTranslateY = Math.floor(
      (tempTanslateY - upperTranslateY) * LEFT_SHIFT8
    );

    compressed1 += upperTranslateY;
    compressed2 += lowerTranslateY;

    scratchCartesian2$8.x = bottomLeftX;
    scratchCartesian2$8.y = bottomLeftY;
    var compressedTexCoordsLL = AttributeCompression.compressTextureCoordinates(
      scratchCartesian2$8
    );
    scratchCartesian2$8.x = topRightX;
    var compressedTexCoordsLR = AttributeCompression.compressTextureCoordinates(
      scratchCartesian2$8
    );
    scratchCartesian2$8.y = topRightY;
    var compressedTexCoordsUR = AttributeCompression.compressTextureCoordinates(
      scratchCartesian2$8
    );
    scratchCartesian2$8.x = bottomLeftX;
    var compressedTexCoordsUL = AttributeCompression.compressTextureCoordinates(
      scratchCartesian2$8
    );

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, compressed0, compressed1, compressed2, compressedTexCoordsLL);
    } else {
      i = billboard._index * 4;
      writer(
        i + 0,
        compressed0 + LOWER_LEFT,
        compressed1,
        compressed2,
        compressedTexCoordsLL
      );
      writer(
        i + 1,
        compressed0 + LOWER_RIGHT,
        compressed1,
        compressed2,
        compressedTexCoordsLR
      );
      writer(
        i + 2,
        compressed0 + UPPER_RIGHT,
        compressed1,
        compressed2,
        compressedTexCoordsUR
      );
      writer(
        i + 3,
        compressed0 + UPPER_LEFT,
        compressed1,
        compressed2,
        compressedTexCoordsUL
      );
    }
  }

  function writeCompressedAttrib1(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.compressedAttribute1];
    var alignedAxis = billboard.alignedAxis;
    if (!Cartesian3.equals(alignedAxis, Cartesian3.ZERO)) {
      billboardCollection._shaderAlignedAxis = true;
    }

    var near = 0.0;
    var nearValue = 1.0;
    var far = 1.0;
    var farValue = 1.0;

    var translucency = billboard.translucencyByDistance;
    if (defined(translucency)) {
      near = translucency.near;
      nearValue = translucency.nearValue;
      far = translucency.far;
      farValue = translucency.farValue;

      if (nearValue !== 1.0 || farValue !== 1.0) {
        // translucency by distance calculation in shader need not be enabled
        // until a billboard with near and far !== 1.0 is found
        billboardCollection._shaderTranslucencyByDistance = true;
      }
    }

    var width = 0;
    var index = billboard._imageIndex;
    if (index !== -1) {
      var imageRectangle = textureAtlasCoordinates[index];

      //>>includeStart('debug', pragmas.debug);
      if (!defined(imageRectangle)) {
        throw new DeveloperError("Invalid billboard image index: " + index);
      }
      //>>includeEnd('debug');

      width = imageRectangle.width;
    }

    var textureWidth = billboardCollection._textureAtlas.texture.width;
    var imageWidth = Math.round(
      defaultValue(billboard.width, textureWidth * width)
    );
    billboardCollection._maxSize = Math.max(
      billboardCollection._maxSize,
      imageWidth
    );

    var compressed0 = CesiumMath.clamp(imageWidth, 0.0, LEFT_SHIFT16);
    var compressed1 = 0.0;

    if (
      Math.abs(Cartesian3.magnitudeSquared(alignedAxis) - 1.0) <
      CesiumMath.EPSILON6
    ) {
      compressed1 = AttributeCompression.octEncodeFloat(alignedAxis);
    }

    nearValue = CesiumMath.clamp(nearValue, 0.0, 1.0);
    nearValue = nearValue === 1.0 ? 255.0 : (nearValue * 255.0) | 0;
    compressed0 = compressed0 * LEFT_SHIFT8 + nearValue;

    farValue = CesiumMath.clamp(farValue, 0.0, 1.0);
    farValue = farValue === 1.0 ? 255.0 : (farValue * 255.0) | 0;
    compressed1 = compressed1 * LEFT_SHIFT8 + farValue;

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, compressed0, compressed1, near, far);
    } else {
      i = billboard._index * 4;
      writer(i + 0, compressed0, compressed1, near, far);
      writer(i + 1, compressed0, compressed1, near, far);
      writer(i + 2, compressed0, compressed1, near, far);
      writer(i + 3, compressed0, compressed1, near, far);
    }
  }

  function writeCompressedAttrib2(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.compressedAttribute2];
    var color = billboard.color;
    var pickColor = !defined(billboardCollection._batchTable)
      ? billboard.getPickId(frameState.context).color
      : Color.WHITE;
    var sizeInMeters = billboard.sizeInMeters ? 1.0 : 0.0;
    var validAlignedAxis =
      Math.abs(Cartesian3.magnitudeSquared(billboard.alignedAxis) - 1.0) <
      CesiumMath.EPSILON6
        ? 1.0
        : 0.0;

    billboardCollection._allSizedInMeters =
      billboardCollection._allSizedInMeters && sizeInMeters === 1.0;

    var height = 0;
    var index = billboard._imageIndex;
    if (index !== -1) {
      var imageRectangle = textureAtlasCoordinates[index];

      //>>includeStart('debug', pragmas.debug);
      if (!defined(imageRectangle)) {
        throw new DeveloperError("Invalid billboard image index: " + index);
      }
      //>>includeEnd('debug');

      height = imageRectangle.height;
    }

    var dimensions = billboardCollection._textureAtlas.texture.dimensions;
    var imageHeight = Math.round(
      defaultValue(billboard.height, dimensions.y * height)
    );
    billboardCollection._maxSize = Math.max(
      billboardCollection._maxSize,
      imageHeight
    );
    var labelHorizontalOrigin = defaultValue(
      billboard._labelHorizontalOrigin,
      -2
    );
    labelHorizontalOrigin += 2;
    var compressed3 = imageHeight * LEFT_SHIFT2 + labelHorizontalOrigin;

    var red = Color.floatToByte(color.red);
    var green = Color.floatToByte(color.green);
    var blue = Color.floatToByte(color.blue);
    var compressed0 = red * LEFT_SHIFT16 + green * LEFT_SHIFT8 + blue;

    red = Color.floatToByte(pickColor.red);
    green = Color.floatToByte(pickColor.green);
    blue = Color.floatToByte(pickColor.blue);
    var compressed1 = red * LEFT_SHIFT16 + green * LEFT_SHIFT8 + blue;

    var compressed2 =
      Color.floatToByte(color.alpha) * LEFT_SHIFT16 +
      Color.floatToByte(pickColor.alpha) * LEFT_SHIFT8;
    compressed2 += sizeInMeters * 2.0 + validAlignedAxis;

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, compressed0, compressed1, compressed2, compressed3);
    } else {
      i = billboard._index * 4;
      writer(i + 0, compressed0, compressed1, compressed2, compressed3);
      writer(i + 1, compressed0, compressed1, compressed2, compressed3);
      writer(i + 2, compressed0, compressed1, compressed2, compressed3);
      writer(i + 3, compressed0, compressed1, compressed2, compressed3);
    }
  }

  function writeEyeOffset(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.eyeOffset];
    var eyeOffset = billboard.eyeOffset;

    // For billboards that are clamped to ground, move it slightly closer to the camera
    var eyeOffsetZ = eyeOffset.z;
    if (billboard._heightReference !== HeightReference$1.NONE) {
      eyeOffsetZ *= 1.005;
    }
    billboardCollection._maxEyeOffset = Math.max(
      billboardCollection._maxEyeOffset,
      Math.abs(eyeOffset.x),
      Math.abs(eyeOffset.y),
      Math.abs(eyeOffsetZ)
    );

    if (billboardCollection._instanced) {
      var width = 0;
      var height = 0;
      var index = billboard._imageIndex;
      if (index !== -1) {
        var imageRectangle = textureAtlasCoordinates[index];

        //>>includeStart('debug', pragmas.debug);
        if (!defined(imageRectangle)) {
          throw new DeveloperError("Invalid billboard image index: " + index);
        }
        //>>includeEnd('debug');

        width = imageRectangle.width;
        height = imageRectangle.height;
      }

      scratchCartesian2$8.x = width;
      scratchCartesian2$8.y = height;
      var compressedTexCoordsRange = AttributeCompression.compressTextureCoordinates(
        scratchCartesian2$8
      );

      i = billboard._index;
      writer(i, eyeOffset.x, eyeOffset.y, eyeOffsetZ, compressedTexCoordsRange);
    } else {
      i = billboard._index * 4;
      writer(i + 0, eyeOffset.x, eyeOffset.y, eyeOffsetZ, 0.0);
      writer(i + 1, eyeOffset.x, eyeOffset.y, eyeOffsetZ, 0.0);
      writer(i + 2, eyeOffset.x, eyeOffset.y, eyeOffsetZ, 0.0);
      writer(i + 3, eyeOffset.x, eyeOffset.y, eyeOffsetZ, 0.0);
    }
  }

  function writeScaleByDistance(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.scaleByDistance];
    var near = 0.0;
    var nearValue = 1.0;
    var far = 1.0;
    var farValue = 1.0;

    var scale = billboard.scaleByDistance;
    if (defined(scale)) {
      near = scale.near;
      nearValue = scale.nearValue;
      far = scale.far;
      farValue = scale.farValue;

      if (nearValue !== 1.0 || farValue !== 1.0) {
        // scale by distance calculation in shader need not be enabled
        // until a billboard with near and far !== 1.0 is found
        billboardCollection._shaderScaleByDistance = true;
      }
    }

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, near, nearValue, far, farValue);
    } else {
      i = billboard._index * 4;
      writer(i + 0, near, nearValue, far, farValue);
      writer(i + 1, near, nearValue, far, farValue);
      writer(i + 2, near, nearValue, far, farValue);
      writer(i + 3, near, nearValue, far, farValue);
    }
  }

  function writePixelOffsetScaleByDistance(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.pixelOffsetScaleByDistance];
    var near = 0.0;
    var nearValue = 1.0;
    var far = 1.0;
    var farValue = 1.0;

    var pixelOffsetScale = billboard.pixelOffsetScaleByDistance;
    if (defined(pixelOffsetScale)) {
      near = pixelOffsetScale.near;
      nearValue = pixelOffsetScale.nearValue;
      far = pixelOffsetScale.far;
      farValue = pixelOffsetScale.farValue;

      if (nearValue !== 1.0 || farValue !== 1.0) {
        // pixelOffsetScale by distance calculation in shader need not be enabled
        // until a billboard with near and far !== 1.0 is found
        billboardCollection._shaderPixelOffsetScaleByDistance = true;
      }
    }

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, near, nearValue, far, farValue);
    } else {
      i = billboard._index * 4;
      writer(i + 0, near, nearValue, far, farValue);
      writer(i + 1, near, nearValue, far, farValue);
      writer(i + 2, near, nearValue, far, farValue);
      writer(i + 3, near, nearValue, far, farValue);
    }
  }

  function writeCompressedAttribute3(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    var i;
    var writer = vafWriters[attributeLocations.compressedAttribute3];
    var near = 0.0;
    var far = Number.MAX_VALUE;

    var distanceDisplayCondition = billboard.distanceDisplayCondition;
    if (defined(distanceDisplayCondition)) {
      near = distanceDisplayCondition.near;
      far = distanceDisplayCondition.far;

      near *= near;
      far *= far;

      billboardCollection._shaderDistanceDisplayCondition = true;
    }

    var disableDepthTestDistance = billboard.disableDepthTestDistance;
    var clampToGround =
      billboard.heightReference === HeightReference$1.CLAMP_TO_GROUND &&
      frameState.context.depthTexture;
    if (!defined(disableDepthTestDistance)) {
      disableDepthTestDistance = clampToGround ? 5000.0 : 0.0;
    }

    disableDepthTestDistance *= disableDepthTestDistance;
    if (clampToGround || disableDepthTestDistance > 0.0) {
      billboardCollection._shaderDisableDepthDistance = true;
      if (disableDepthTestDistance === Number.POSITIVE_INFINITY) {
        disableDepthTestDistance = -1.0;
      }
    }

    var imageHeight;
    var imageWidth;

    if (!defined(billboard._labelDimensions)) {
      var height = 0;
      var width = 0;
      var index = billboard._imageIndex;
      if (index !== -1) {
        var imageRectangle = textureAtlasCoordinates[index];

        //>>includeStart('debug', pragmas.debug);
        if (!defined(imageRectangle)) {
          throw new DeveloperError("Invalid billboard image index: " + index);
        }
        //>>includeEnd('debug');

        height = imageRectangle.height;
        width = imageRectangle.width;
      }

      imageHeight = Math.round(
        defaultValue(
          billboard.height,
          billboardCollection._textureAtlas.texture.dimensions.y * height
        )
      );

      var textureWidth = billboardCollection._textureAtlas.texture.width;
      imageWidth = Math.round(
        defaultValue(billboard.width, textureWidth * width)
      );
    } else {
      imageWidth = billboard._labelDimensions.x;
      imageHeight = billboard._labelDimensions.y;
    }

    var w = Math.floor(CesiumMath.clamp(imageWidth, 0.0, LEFT_SHIFT12));
    var h = Math.floor(CesiumMath.clamp(imageHeight, 0.0, LEFT_SHIFT12));
    var dimensions = w * LEFT_SHIFT12 + h;

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, near, far, disableDepthTestDistance, dimensions);
    } else {
      i = billboard._index * 4;
      writer(i + 0, near, far, disableDepthTestDistance, dimensions);
      writer(i + 1, near, far, disableDepthTestDistance, dimensions);
      writer(i + 2, near, far, disableDepthTestDistance, dimensions);
      writer(i + 3, near, far, disableDepthTestDistance, dimensions);
    }
  }

  function writeTextureCoordinateBoundsOrLabelTranslate(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    if (billboard.heightReference === HeightReference$1.CLAMP_TO_GROUND) {
      var scene = billboardCollection._scene;
      var context = frameState.context;
      var globeTranslucent = frameState.globeTranslucencyState.translucent;
      var depthTestAgainstTerrain =
        defined(scene.globe) && scene.globe.depthTestAgainstTerrain;

      // Only do manual depth test if the globe is opaque and writes depth
      billboardCollection._shaderClampToGround =
        context.depthTexture && !globeTranslucent && depthTestAgainstTerrain;
    }
    var i;
    var writer =
      vafWriters[attributeLocations.textureCoordinateBoundsOrLabelTranslate];

    if (ContextLimits.maximumVertexTextureImageUnits > 0) {
      //write _labelTranslate, used by depth testing in the vertex shader
      var translateX = 0;
      var translateY = 0;
      if (defined(billboard._labelTranslate)) {
        translateX = billboard._labelTranslate.x;
        translateY = billboard._labelTranslate.y;
      }
      if (billboardCollection._instanced) {
        i = billboard._index;
        writer(i, translateX, translateY, 0.0, 0.0);
      } else {
        i = billboard._index * 4;
        writer(i + 0, translateX, translateY, 0.0, 0.0);
        writer(i + 1, translateX, translateY, 0.0, 0.0);
        writer(i + 2, translateX, translateY, 0.0, 0.0);
        writer(i + 3, translateX, translateY, 0.0, 0.0);
      }
      return;
    }

    //write texture coordinate bounds, used by depth testing in fragment shader
    var minX = 0;
    var minY = 0;
    var width = 0;
    var height = 0;
    var index = billboard._imageIndex;
    if (index !== -1) {
      var imageRectangle = textureAtlasCoordinates[index];

      //>>includeStart('debug', pragmas.debug);
      if (!defined(imageRectangle)) {
        throw new DeveloperError("Invalid billboard image index: " + index);
      }
      //>>includeEnd('debug');

      minX = imageRectangle.x;
      minY = imageRectangle.y;
      width = imageRectangle.width;
      height = imageRectangle.height;
    }
    var maxX = minX + width;
    var maxY = minY + height;

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, minX, minY, maxX, maxY);
    } else {
      i = billboard._index * 4;
      writer(i + 0, minX, minY, maxX, maxY);
      writer(i + 1, minX, minY, maxX, maxY);
      writer(i + 2, minX, minY, maxX, maxY);
      writer(i + 3, minX, minY, maxX, maxY);
    }
  }

  function writeBatchId(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    if (!defined(billboardCollection._batchTable)) {
      return;
    }

    var writer = vafWriters[attributeLocations.a_batchId];
    var id = billboard._batchIndex;

    var i;
    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, id);
    } else {
      i = billboard._index * 4;
      writer(i + 0, id);
      writer(i + 1, id);
      writer(i + 2, id);
      writer(i + 3, id);
    }
  }

  function writeSDF(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    if (!billboardCollection._sdf) {
      return;
    }

    var i;
    var writer = vafWriters[attributeLocations.sdf];

    var outlineColor = billboard.outlineColor;
    var outlineWidth = billboard.outlineWidth;

    var red = Color.floatToByte(outlineColor.red);
    var green = Color.floatToByte(outlineColor.green);
    var blue = Color.floatToByte(outlineColor.blue);
    var compressed0 = red * LEFT_SHIFT16 + green * LEFT_SHIFT8 + blue;

    // Compute the relative outline distance
    var outlineDistance = outlineWidth / SDFSettings$1.RADIUS;
    var compressed1 =
      Color.floatToByte(outlineColor.alpha) * LEFT_SHIFT16 +
      Color.floatToByte(outlineDistance) * LEFT_SHIFT8;

    if (billboardCollection._instanced) {
      i = billboard._index;
      writer(i, compressed0, compressed1);
    } else {
      i = billboard._index * 4;
      writer(i + 0, compressed0 + LOWER_LEFT, compressed1);
      writer(i + 1, compressed0 + LOWER_RIGHT, compressed1);
      writer(i + 2, compressed0 + UPPER_RIGHT, compressed1);
      writer(i + 3, compressed0 + UPPER_LEFT, compressed1);
    }
  }

  function writeBillboard(
    billboardCollection,
    frameState,
    textureAtlasCoordinates,
    vafWriters,
    billboard
  ) {
    writePositionScaleAndRotation(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeCompressedAttrib0(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeCompressedAttrib1(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeCompressedAttrib2(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeEyeOffset(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeScaleByDistance(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writePixelOffsetScaleByDistance(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeCompressedAttribute3(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeTextureCoordinateBoundsOrLabelTranslate(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeBatchId(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
    writeSDF(
      billboardCollection,
      frameState,
      textureAtlasCoordinates,
      vafWriters,
      billboard
    );
  }

  function recomputeActualPositions(
    billboardCollection,
    billboards,
    length,
    frameState,
    modelMatrix,
    recomputeBoundingVolume
  ) {
    var boundingVolume;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      boundingVolume = billboardCollection._baseVolume;
      billboardCollection._boundingVolumeDirty = true;
    } else {
      boundingVolume = billboardCollection._baseVolume2D;
    }

    var positions = [];
    for (var i = 0; i < length; ++i) {
      var billboard = billboards[i];
      var position = billboard.position;
      var actualPosition = Billboard._computeActualPosition(
        billboard,
        position,
        frameState,
        modelMatrix
      );
      if (defined(actualPosition)) {
        billboard._setActualPosition(actualPosition);

        if (recomputeBoundingVolume) {
          positions.push(actualPosition);
        } else {
          BoundingSphere.expand(boundingVolume, actualPosition, boundingVolume);
        }
      }
    }

    if (recomputeBoundingVolume) {
      BoundingSphere.fromPoints(positions, boundingVolume);
    }
  }

  function updateMode(billboardCollection, frameState) {
    var mode = frameState.mode;

    var billboards = billboardCollection._billboards;
    var billboardsToUpdate = billboardCollection._billboardsToUpdate;
    var modelMatrix = billboardCollection._modelMatrix;

    if (
      billboardCollection._createVertexArray ||
      billboardCollection._mode !== mode ||
      (mode !== SceneMode$1.SCENE3D &&
        !Matrix4.equals(modelMatrix, billboardCollection.modelMatrix))
    ) {
      billboardCollection._mode = mode;
      Matrix4.clone(billboardCollection.modelMatrix, modelMatrix);
      billboardCollection._createVertexArray = true;

      if (
        mode === SceneMode$1.SCENE3D ||
        mode === SceneMode$1.SCENE2D ||
        mode === SceneMode$1.COLUMBUS_VIEW
      ) {
        recomputeActualPositions(
          billboardCollection,
          billboards,
          billboards.length,
          frameState,
          modelMatrix,
          true
        );
      }
    } else if (mode === SceneMode$1.MORPHING) {
      recomputeActualPositions(
        billboardCollection,
        billboards,
        billboards.length,
        frameState,
        modelMatrix,
        true
      );
    } else if (mode === SceneMode$1.SCENE2D || mode === SceneMode$1.COLUMBUS_VIEW) {
      recomputeActualPositions(
        billboardCollection,
        billboardsToUpdate,
        billboardCollection._billboardsToUpdateIndex,
        frameState,
        modelMatrix,
        false
      );
    }
  }

  function updateBoundingVolume(collection, frameState, boundingVolume) {
    var pixelScale = 1.0;
    if (!collection._allSizedInMeters || collection._maxPixelOffset !== 0.0) {
      pixelScale = frameState.camera.getPixelSize(
        boundingVolume,
        frameState.context.drawingBufferWidth,
        frameState.context.drawingBufferHeight
      );
    }

    var size = pixelScale * collection._maxScale * collection._maxSize * 2.0;
    if (collection._allHorizontalCenter && collection._allVerticalCenter) {
      size *= 0.5;
    }

    var offset =
      pixelScale * collection._maxPixelOffset + collection._maxEyeOffset;
    boundingVolume.radius += size + offset;
  }

  function createDebugCommand(billboardCollection, context) {
    var fs;
    fs =
      "uniform sampler2D billboard_texture; \n" +
      "varying vec2 v_textureCoordinates; \n" +
      "void main() \n" +
      "{ \n" +
      "    gl_FragColor = texture2D(billboard_texture, v_textureCoordinates); \n" +
      "} \n";

    var drawCommand = context.createViewportQuadCommand(fs, {
      uniformMap: {
        billboard_texture: function () {
          return billboardCollection._textureAtlas.texture;
        },
      },
    });
    drawCommand.pass = Pass$1.OVERLAY;
    return drawCommand;
  }

  var scratchWriterArray = [];

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {RuntimeError} image with id must be in the atlas.
   */
  BillboardCollection.prototype.update = function (frameState) {
    removeBillboards(this);
    var billboards = this._billboards;
    var billboardsLength = billboards.length;

    var context = frameState.context;
    this._instanced = context.instancedArrays;
    attributeLocations = this._instanced
      ? attributeLocationsInstanced
      : attributeLocationsBatched;
    getIndexBuffer = this._instanced
      ? getIndexBufferInstanced
      : getIndexBufferBatched;

    var textureAtlas = this._textureAtlas;
    if (!defined(textureAtlas)) {
      textureAtlas = this._textureAtlas = new TextureAtlas({
        context: context,
      });

      for (var ii = 0; ii < billboardsLength; ++ii) {
        billboards[ii]._loadImage();
      }
    }

    var textureAtlasCoordinates = textureAtlas.textureCoordinates;
    if (textureAtlasCoordinates.length === 0) {
      // Can't write billboard vertices until we have texture coordinates
      // provided by a texture atlas
      return;
    }

    updateMode(this, frameState);

    billboards = this._billboards;
    billboardsLength = billboards.length;
    var billboardsToUpdate = this._billboardsToUpdate;
    var billboardsToUpdateLength = this._billboardsToUpdateIndex;

    var properties = this._propertiesChanged;

    var textureAtlasGUID = textureAtlas.guid;
    var createVertexArray =
      this._createVertexArray || this._textureAtlasGUID !== textureAtlasGUID;
    this._textureAtlasGUID = textureAtlasGUID;

    var vafWriters;
    var pass = frameState.passes;
    var picking = pass.pick;

    // PERFORMANCE_IDEA: Round robin multiple buffers.
    if (createVertexArray || (!picking && this.computeNewBuffersUsage())) {
      this._createVertexArray = false;

      for (var k = 0; k < NUMBER_OF_PROPERTIES; ++k) {
        properties[k] = 0;
      }

      this._vaf = this._vaf && this._vaf.destroy();

      if (billboardsLength > 0) {
        // PERFORMANCE_IDEA:  Instead of creating a new one, resize like std::vector.
        this._vaf = createVAF(
          context,
          billboardsLength,
          this._buffersUsage,
          this._instanced,
          this._batchTable,
          this._sdf
        );
        vafWriters = this._vaf.writers;

        // Rewrite entire buffer if billboards were added or removed.
        for (var i = 0; i < billboardsLength; ++i) {
          var billboard = this._billboards[i];
          billboard._dirty = false; // In case it needed an update.
          writeBillboard(
            this,
            frameState,
            textureAtlasCoordinates,
            vafWriters,
            billboard
          );
        }

        // Different billboard collections share the same index buffer.
        this._vaf.commit(getIndexBuffer(context));
      }

      this._billboardsToUpdateIndex = 0;
    } else if (billboardsToUpdateLength > 0) {
      // Billboards were modified, but none were added or removed.
      var writers = scratchWriterArray;
      writers.length = 0;

      if (
        properties[POSITION_INDEX$1] ||
        properties[ROTATION_INDEX$1] ||
        properties[SCALE_INDEX$1]
      ) {
        writers.push(writePositionScaleAndRotation);
      }

      if (
        properties[IMAGE_INDEX_INDEX$1] ||
        properties[PIXEL_OFFSET_INDEX$1] ||
        properties[HORIZONTAL_ORIGIN_INDEX$1] ||
        properties[VERTICAL_ORIGIN_INDEX$1] ||
        properties[SHOW_INDEX$1]
      ) {
        writers.push(writeCompressedAttrib0);
        if (this._instanced) {
          writers.push(writeEyeOffset);
        }
      }

      if (
        properties[IMAGE_INDEX_INDEX$1] ||
        properties[ALIGNED_AXIS_INDEX$1] ||
        properties[TRANSLUCENCY_BY_DISTANCE_INDEX$1]
      ) {
        writers.push(writeCompressedAttrib1);
        writers.push(writeCompressedAttrib2);
      }

      if (properties[IMAGE_INDEX_INDEX$1] || properties[COLOR_INDEX$1]) {
        writers.push(writeCompressedAttrib2);
      }

      if (properties[EYE_OFFSET_INDEX$1]) {
        writers.push(writeEyeOffset);
      }

      if (properties[SCALE_BY_DISTANCE_INDEX$1]) {
        writers.push(writeScaleByDistance);
      }

      if (properties[PIXEL_OFFSET_SCALE_BY_DISTANCE_INDEX$1]) {
        writers.push(writePixelOffsetScaleByDistance);
      }

      if (
        properties[DISTANCE_DISPLAY_CONDITION_INDEX] ||
        properties[DISABLE_DEPTH_DISTANCE$1] ||
        properties[IMAGE_INDEX_INDEX$1] ||
        properties[POSITION_INDEX$1]
      ) {
        writers.push(writeCompressedAttribute3);
      }

      if (properties[IMAGE_INDEX_INDEX$1] || properties[POSITION_INDEX$1]) {
        writers.push(writeTextureCoordinateBoundsOrLabelTranslate);
      }

      if (properties[SDF_INDEX$1]) {
        writers.push(writeSDF);
      }

      var numWriters = writers.length;
      vafWriters = this._vaf.writers;

      if (billboardsToUpdateLength / billboardsLength > 0.1) {
        // If more than 10% of billboard change, rewrite the entire buffer.

        // PERFORMANCE_IDEA:  I totally made up 10% :).

        for (var m = 0; m < billboardsToUpdateLength; ++m) {
          var b = billboardsToUpdate[m];
          b._dirty = false;

          for (var n = 0; n < numWriters; ++n) {
            writers[n](this, frameState, textureAtlasCoordinates, vafWriters, b);
          }
        }
        this._vaf.commit(getIndexBuffer(context));
      } else {
        for (var h = 0; h < billboardsToUpdateLength; ++h) {
          var bb = billboardsToUpdate[h];
          bb._dirty = false;

          for (var o = 0; o < numWriters; ++o) {
            writers[o](this, frameState, textureAtlasCoordinates, vafWriters, bb);
          }

          if (this._instanced) {
            this._vaf.subCommit(bb._index, 1);
          } else {
            this._vaf.subCommit(bb._index * 4, 4);
          }
        }
        this._vaf.endSubCommits();
      }

      this._billboardsToUpdateIndex = 0;
    }

    // If the number of total billboards ever shrinks considerably
    // Truncate billboardsToUpdate so that we free memory that we're
    // not going to be using.
    if (billboardsToUpdateLength > billboardsLength * 1.5) {
      billboardsToUpdate.length = billboardsLength;
    }

    if (!defined(this._vaf) || !defined(this._vaf.va)) {
      return;
    }

    if (this._boundingVolumeDirty) {
      this._boundingVolumeDirty = false;
      BoundingSphere.transform(
        this._baseVolume,
        this.modelMatrix,
        this._baseVolumeWC
      );
    }

    var boundingVolume;
    var modelMatrix = Matrix4.IDENTITY;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      modelMatrix = this.modelMatrix;
      boundingVolume = BoundingSphere.clone(
        this._baseVolumeWC,
        this._boundingVolume
      );
    } else {
      boundingVolume = BoundingSphere.clone(
        this._baseVolume2D,
        this._boundingVolume
      );
    }
    updateBoundingVolume(this, frameState, boundingVolume);

    var blendOptionChanged = this._blendOption !== this.blendOption;
    this._blendOption = this.blendOption;

    if (blendOptionChanged) {
      if (
        this._blendOption === BlendOption$1.OPAQUE ||
        this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT
      ) {
        this._rsOpaque = RenderState.fromCache({
          depthTest: {
            enabled: true,
            func: WebGLConstants$1.LESS,
          },
          depthMask: true,
        });
      } else {
        this._rsOpaque = undefined;
      }

      // If OPAQUE_AND_TRANSLUCENT is in use, only the opaque pass gets the benefit of the depth buffer,
      // not the translucent pass.  Otherwise, if the TRANSLUCENT pass is on its own, it turns on
      // a depthMask in lieu of full depth sorting (because it has opaque-ish fragments that look bad in OIT).
      // When the TRANSLUCENT depth mask is in use, label backgrounds require the depth func to be LEQUAL.
      var useTranslucentDepthMask = this._blendOption === BlendOption$1.TRANSLUCENT;

      if (
        this._blendOption === BlendOption$1.TRANSLUCENT ||
        this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT
      ) {
        this._rsTranslucent = RenderState.fromCache({
          depthTest: {
            enabled: true,
            func: useTranslucentDepthMask
              ? WebGLConstants$1.LEQUAL
              : WebGLConstants$1.LESS,
          },
          depthMask: useTranslucentDepthMask,
          blending: BlendingState$1.ALPHA_BLEND,
        });
      } else {
        this._rsTranslucent = undefined;
      }
    }

    this._shaderDisableDepthDistance =
      this._shaderDisableDepthDistance ||
      frameState.minimumDisableDepthTestDistance !== 0.0;

    var vsSource;
    var fsSource;
    var vs;
    var fs;
    var vertDefines;

    var supportVSTextureReads = ContextLimits.maximumVertexTextureImageUnits > 0;

    if (
      blendOptionChanged ||
      this._shaderRotation !== this._compiledShaderRotation ||
      this._shaderAlignedAxis !== this._compiledShaderAlignedAxis ||
      this._shaderScaleByDistance !== this._compiledShaderScaleByDistance ||
      this._shaderTranslucencyByDistance !==
        this._compiledShaderTranslucencyByDistance ||
      this._shaderPixelOffsetScaleByDistance !==
        this._compiledShaderPixelOffsetScaleByDistance ||
      this._shaderDistanceDisplayCondition !==
        this._compiledShaderDistanceDisplayCondition ||
      this._shaderDisableDepthDistance !==
        this._compiledShaderDisableDepthDistance ||
      this._shaderClampToGround !== this._compiledShaderClampToGround ||
      this._sdf !== this._compiledSDF
    ) {
      vsSource = BillboardCollectionVS;
      fsSource = BillboardCollectionFS;

      vertDefines = [];
      if (defined(this._batchTable)) {
        vertDefines.push("VECTOR_TILE");
        vsSource = this._batchTable.getVertexShaderCallback(
          false,
          "a_batchId",
          undefined
        )(vsSource);
        fsSource = this._batchTable.getFragmentShaderCallback(
          false,
          undefined
        )(fsSource);
      }

      vs = new ShaderSource({
        defines: vertDefines,
        sources: [vsSource],
      });
      if (this._instanced) {
        vs.defines.push("INSTANCED");
      }
      if (this._shaderRotation) {
        vs.defines.push("ROTATION");
      }
      if (this._shaderAlignedAxis) {
        vs.defines.push("ALIGNED_AXIS");
      }
      if (this._shaderScaleByDistance) {
        vs.defines.push("EYE_DISTANCE_SCALING");
      }
      if (this._shaderTranslucencyByDistance) {
        vs.defines.push("EYE_DISTANCE_TRANSLUCENCY");
      }
      if (this._shaderPixelOffsetScaleByDistance) {
        vs.defines.push("EYE_DISTANCE_PIXEL_OFFSET");
      }
      if (this._shaderDistanceDisplayCondition) {
        vs.defines.push("DISTANCE_DISPLAY_CONDITION");
      }
      if (this._shaderDisableDepthDistance) {
        vs.defines.push("DISABLE_DEPTH_DISTANCE");
      }
      if (this._shaderClampToGround) {
        if (supportVSTextureReads) {
          vs.defines.push("VERTEX_DEPTH_CHECK");
        } else {
          vs.defines.push("FRAGMENT_DEPTH_CHECK");
        }
      }

      var sdfEdge = 1.0 - SDFSettings$1.CUTOFF;

      if (this._sdf) {
        vs.defines.push("SDF");
      }

      var vectorFragDefine = defined(this._batchTable) ? "VECTOR_TILE" : "";

      if (this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT) {
        fs = new ShaderSource({
          defines: ["OPAQUE", vectorFragDefine],
          sources: [fsSource],
        });
        if (this._shaderClampToGround) {
          if (supportVSTextureReads) {
            fs.defines.push("VERTEX_DEPTH_CHECK");
          } else {
            fs.defines.push("FRAGMENT_DEPTH_CHECK");
          }
        }

        if (this._sdf) {
          fs.defines.push("SDF");
          fs.defines.push("SDF_EDGE " + sdfEdge);
        }

        this._sp = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._sp,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        });

        fs = new ShaderSource({
          defines: ["TRANSLUCENT", vectorFragDefine],
          sources: [fsSource],
        });
        if (this._shaderClampToGround) {
          if (supportVSTextureReads) {
            fs.defines.push("VERTEX_DEPTH_CHECK");
          } else {
            fs.defines.push("FRAGMENT_DEPTH_CHECK");
          }
        }
        if (this._sdf) {
          fs.defines.push("SDF");
          fs.defines.push("SDF_EDGE " + sdfEdge);
        }
        this._spTranslucent = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._spTranslucent,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        });
      }

      if (this._blendOption === BlendOption$1.OPAQUE) {
        fs = new ShaderSource({
          defines: [vectorFragDefine],
          sources: [fsSource],
        });
        if (this._shaderClampToGround) {
          if (supportVSTextureReads) {
            fs.defines.push("VERTEX_DEPTH_CHECK");
          } else {
            fs.defines.push("FRAGMENT_DEPTH_CHECK");
          }
        }
        if (this._sdf) {
          fs.defines.push("SDF");
          fs.defines.push("SDF_EDGE " + sdfEdge);
        }
        this._sp = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._sp,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        });
      }

      if (this._blendOption === BlendOption$1.TRANSLUCENT) {
        fs = new ShaderSource({
          defines: [vectorFragDefine],
          sources: [fsSource],
        });
        if (this._shaderClampToGround) {
          if (supportVSTextureReads) {
            fs.defines.push("VERTEX_DEPTH_CHECK");
          } else {
            fs.defines.push("FRAGMENT_DEPTH_CHECK");
          }
        }
        if (this._sdf) {
          fs.defines.push("SDF");
          fs.defines.push("SDF_EDGE " + sdfEdge);
        }
        this._spTranslucent = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._spTranslucent,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        });
      }

      this._compiledShaderRotation = this._shaderRotation;
      this._compiledShaderAlignedAxis = this._shaderAlignedAxis;
      this._compiledShaderScaleByDistance = this._shaderScaleByDistance;
      this._compiledShaderTranslucencyByDistance = this._shaderTranslucencyByDistance;
      this._compiledShaderPixelOffsetScaleByDistance = this._shaderPixelOffsetScaleByDistance;
      this._compiledShaderDistanceDisplayCondition = this._shaderDistanceDisplayCondition;
      this._compiledShaderDisableDepthDistance = this._shaderDisableDepthDistance;
      this._compiledShaderClampToGround = this._shaderClampToGround;
      this._compiledSDF = this._sdf;
    }

    var commandList = frameState.commandList;

    if (pass.render || pass.pick) {
      var colorList = this._colorCommands;

      var opaque = this._blendOption === BlendOption$1.OPAQUE;
      var opaqueAndTranslucent =
        this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT;

      var va = this._vaf.va;
      var vaLength = va.length;

      var uniforms = this._uniforms;
      var pickId;
      if (defined(this._batchTable)) {
        uniforms = this._batchTable.getUniformMapCallback()(uniforms);
        pickId = this._batchTable.getPickId();
      } else {
        pickId = "v_pickColor";
      }

      colorList.length = vaLength;
      var totalLength = opaqueAndTranslucent ? vaLength * 2 : vaLength;
      for (var j = 0; j < totalLength; ++j) {
        var command = colorList[j];
        if (!defined(command)) {
          command = colorList[j] = new DrawCommand();
        }

        var opaqueCommand = opaque || (opaqueAndTranslucent && j % 2 === 0);

        command.pass =
          opaqueCommand || !opaqueAndTranslucent ? Pass$1.OPAQUE : Pass$1.TRANSLUCENT;
        command.owner = this;

        var index = opaqueAndTranslucent ? Math.floor(j / 2.0) : j;
        command.boundingVolume = boundingVolume;
        command.modelMatrix = modelMatrix;
        command.count = va[index].indicesCount;
        command.shaderProgram = opaqueCommand ? this._sp : this._spTranslucent;
        command.uniformMap = uniforms;
        command.vertexArray = va[index].va;
        command.renderState = opaqueCommand
          ? this._rsOpaque
          : this._rsTranslucent;
        command.debugShowBoundingVolume = this.debugShowBoundingVolume;
        command.pickId = pickId;

        if (this._instanced) {
          command.count = 6;
          command.instanceCount = billboardsLength;
        }

        commandList.push(command);
      }

      if (this.debugShowTextureAtlas) {
        if (!defined(this.debugCommand)) {
          this.debugCommand = createDebugCommand(this, frameState.context);
        }

        commandList.push(this.debugCommand);
      }
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see BillboardCollection#destroy
   */
  BillboardCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * billboards = billboards && billboards.destroy();
   *
   * @see BillboardCollection#isDestroyed
   */
  BillboardCollection.prototype.destroy = function () {
    if (defined(this._removeCallbackFunc)) {
      this._removeCallbackFunc();
      this._removeCallbackFunc = undefined;
    }

    this._textureAtlas =
      this._destroyTextureAtlas &&
      this._textureAtlas &&
      this._textureAtlas.destroy();
    this._sp = this._sp && this._sp.destroy();
    this._spTranslucent = this._spTranslucent && this._spTranslucent.destroy();
    this._vaf = this._vaf && this._vaf.destroy();
    destroyBillboards(this._billboards);

    return destroyObject(this);
  };

  /**
   * Creates a {@link createBillboardPointCallback.CanvasFunction} that will create a canvas with a point.
   *
   * @param {Number} centerAlpha The alpha of the center of the point. The value must be in the range [0.0, 1.0].
   * @param {String} cssColor The CSS color string.
   * @param {String} cssOutlineColor The CSS color of the point outline.
   * @param {Number} cssOutlineWidth The width of the outline in pixels.
   * @param {Number} pixelSize The size of the point in pixels.
   * @return {createBillboardPointCallback.CanvasFunction} The function that will return a canvas with the point drawn on it.
   *
   * @private
   */
  function createBillboardPointCallback(
    centerAlpha,
    cssColor,
    cssOutlineColor,
    cssOutlineWidth,
    pixelSize
  ) {
    return function () {
      var canvas = document.createElement("canvas");

      var length = pixelSize + 2 * cssOutlineWidth;
      canvas.height = canvas.width = length;

      var context2D = canvas.getContext("2d");
      context2D.clearRect(0, 0, length, length);

      if (cssOutlineWidth !== 0) {
        context2D.beginPath();
        context2D.arc(length / 2, length / 2, length / 2, 0, 2 * Math.PI, true);
        context2D.closePath();
        context2D.fillStyle = cssOutlineColor;
        context2D.fill();
        // Punch a hole in the center if needed.
        if (centerAlpha < 1.0) {
          context2D.save();
          context2D.globalCompositeOperation = "destination-out";
          context2D.beginPath();
          context2D.arc(
            length / 2,
            length / 2,
            pixelSize / 2,
            0,
            2 * Math.PI,
            true
          );
          context2D.closePath();
          context2D.fillStyle = "black";
          context2D.fill();
          context2D.restore();
        }
      }

      context2D.beginPath();
      context2D.arc(length / 2, length / 2, pixelSize / 2, 0, 2 * Math.PI, true);
      context2D.closePath();
      context2D.fillStyle = cssColor;
      context2D.fill();

      return canvas;
    };
  }

  /**
   * A point feature of a {@link Cesium3DTileset}.
   * <p>
   * Provides access to a feature's properties stored in the tile's batch table, as well
   * as the ability to show/hide a feature and change its point properties
   * </p>
   * <p>
   * Modifications to a <code>Cesium3DTilePointFeature</code> object have the lifetime of the tile's
   * content.  If the tile's content is unloaded, e.g., due to it going out of view and needing
   * to free space in the cache for visible tiles, listen to the {@link Cesium3DTileset#tileUnload} event to save any
   * modifications. Also listen to the {@link Cesium3DTileset#tileVisible} event to reapply any modifications.
   * </p>
   * <p>
   * Do not construct this directly.  Access it through {@link Cesium3DTileContent#getFeature}
   * or picking using {@link Scene#pick} and {@link Scene#pickPosition}.
   * </p>
   *
   * @alias Cesium3DTilePointFeature
   * @constructor
   *
   * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
   *
   * @example
   * // On mouse over, display all the properties for a feature in the console log.
   * handler.setInputAction(function(movement) {
   *     var feature = scene.pick(movement.endPosition);
   *     if (feature instanceof Cesium.Cesium3DTilePointFeature) {
   *         var propertyNames = feature.getPropertyNames();
   *         var length = propertyNames.length;
   *         for (var i = 0; i < length; ++i) {
   *             var propertyName = propertyNames[i];
   *             console.log(propertyName + ': ' + feature.getProperty(propertyName));
   *         }
   *     }
   * }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
   */
  function Cesium3DTilePointFeature(
    content,
    batchId,
    billboard,
    label,
    polyline
  ) {
    this._content = content;
    this._billboard = billboard;
    this._label = label;
    this._polyline = polyline;

    this._batchId = batchId;
    this._billboardImage = undefined;
    this._billboardColor = undefined;
    this._billboardOutlineColor = undefined;
    this._billboardOutlineWidth = undefined;
    this._billboardSize = undefined;
    this._pointSize = undefined;
    this._color = undefined;
    this._pointSize = undefined;
    this._pointOutlineColor = undefined;
    this._pointOutlineWidth = undefined;
    this._heightOffset = undefined;

    this._pickIds = new Array(3);

    setBillboardImage(this);
  }

  var scratchCartographic$5 = new Cartographic();

  Object.defineProperties(Cesium3DTilePointFeature.prototype, {
    /**
     * Gets or sets if the feature will be shown. This is set for all features
     * when a style's show is evaluated.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Boolean}
     *
     * @default true
     */
    show: {
      get: function () {
        return this._label.show;
      },
      set: function (value) {
        this._label.show = value;
        this._billboard.show = value;
        this._polyline.show = value;
      },
    },

    /**
     * Gets or sets the color of the point of this feature.
     * <p>
     * Only applied when <code>image</code> is <code>undefined</code>.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Color}
     */
    color: {
      get: function () {
        return this._color;
      },
      set: function (value) {
        this._color = Color.clone(value, this._color);
        setBillboardImage(this);
      },
    },

    /**
     * Gets or sets the point size of this feature.
     * <p>
     * Only applied when <code>image</code> is <code>undefined</code>.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Number}
     */
    pointSize: {
      get: function () {
        return this._pointSize;
      },
      set: function (value) {
        this._pointSize = value;
        setBillboardImage(this);
      },
    },

    /**
     * Gets or sets the point outline color of this feature.
     * <p>
     * Only applied when <code>image</code> is <code>undefined</code>.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Color}
     */
    pointOutlineColor: {
      get: function () {
        return this._pointOutlineColor;
      },
      set: function (value) {
        this._pointOutlineColor = Color.clone(value, this._pointOutlineColor);
        setBillboardImage(this);
      },
    },

    /**
     * Gets or sets the point outline width in pixels of this feature.
     * <p>
     * Only applied when <code>image</code> is <code>undefined</code>.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Number}
     */
    pointOutlineWidth: {
      get: function () {
        return this._pointOutlineWidth;
      },
      set: function (value) {
        this._pointOutlineWidth = value;
        setBillboardImage(this);
      },
    },

    /**
     * Gets or sets the label color of this feature.
     * <p>
     * The color will be applied to the label if <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Color}
     */
    labelColor: {
      get: function () {
        return this._label.fillColor;
      },
      set: function (value) {
        this._label.fillColor = value;
        this._polyline.show = this._label.show && value.alpha > 0.0;
      },
    },

    /**
     * Gets or sets the label outline color of this feature.
     * <p>
     * The outline color will be applied to the label if <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Color}
     */
    labelOutlineColor: {
      get: function () {
        return this._label.outlineColor;
      },
      set: function (value) {
        this._label.outlineColor = value;
      },
    },

    /**
     * Gets or sets the outline width in pixels of this feature.
     * <p>
     * The outline width will be applied to the point if <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Number}
     */
    labelOutlineWidth: {
      get: function () {
        return this._label.outlineWidth;
      },
      set: function (value) {
        this._label.outlineWidth = value;
      },
    },

    /**
     * Gets or sets the font of this feature.
     * <p>
     * Only applied when the <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {String}
     */
    font: {
      get: function () {
        return this._label.font;
      },
      set: function (value) {
        this._label.font = value;
      },
    },

    /**
     * Gets or sets the fill and outline style of this feature.
     * <p>
     * Only applied when <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {LabelStyle}
     */
    labelStyle: {
      get: function () {
        return this._label.style;
      },
      set: function (value) {
        this._label.style = value;
      },
    },

    /**
     * Gets or sets the text for this feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {String}
     */
    labelText: {
      get: function () {
        return this._label.text;
      },
      set: function (value) {
        if (!defined(value)) {
          value = "";
        }
        this._label.text = value;
      },
    },

    /**
     * Gets or sets the background color of the text for this feature.
     * <p>
     * Only applied when <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Color}
     */
    backgroundColor: {
      get: function () {
        return this._label.backgroundColor;
      },
      set: function (value) {
        this._label.backgroundColor = value;
      },
    },

    /**
     * Gets or sets the background padding of the text for this feature.
     * <p>
     * Only applied when <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Cartesian2}
     */
    backgroundPadding: {
      get: function () {
        return this._label.backgroundPadding;
      },
      set: function (value) {
        this._label.backgroundPadding = value;
      },
    },

    /**
     * Gets or sets whether to display the background of the text for this feature.
     * <p>
     * Only applied when <code>labelText</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Boolean}
     */
    backgroundEnabled: {
      get: function () {
        return this._label.showBackground;
      },
      set: function (value) {
        this._label.showBackground = value;
      },
    },

    /**
     * Gets or sets the near and far scaling properties for this feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {NearFarScalar}
     */
    scaleByDistance: {
      get: function () {
        return this._label.scaleByDistance;
      },
      set: function (value) {
        this._label.scaleByDistance = value;
        this._billboard.scaleByDistance = value;
      },
    },

    /**
     * Gets or sets the near and far translucency properties for this feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {NearFarScalar}
     */
    translucencyByDistance: {
      get: function () {
        return this._label.translucencyByDistance;
      },
      set: function (value) {
        this._label.translucencyByDistance = value;
        this._billboard.translucencyByDistance = value;
      },
    },

    /**
     * Gets or sets the condition specifying at what distance from the camera that this feature will be displayed.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {DistanceDisplayCondition}
     */
    distanceDisplayCondition: {
      get: function () {
        return this._label.distanceDisplayCondition;
      },
      set: function (value) {
        this._label.distanceDisplayCondition = value;
        this._polyline.distanceDisplayCondition = value;
        this._billboard.distanceDisplayCondition = value;
      },
    },

    /**
     * Gets or sets the height offset in meters of this feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Number}
     */
    heightOffset: {
      get: function () {
        return this._heightOffset;
      },
      set: function (value) {
        var offset = defaultValue(this._heightOffset, 0.0);

        var ellipsoid = this._content.tileset.ellipsoid;
        var cart = ellipsoid.cartesianToCartographic(
          this._billboard.position,
          scratchCartographic$5
        );
        cart.height = cart.height - offset + value;
        var newPosition = ellipsoid.cartographicToCartesian(cart);

        this._billboard.position = newPosition;
        this._label.position = this._billboard.position;
        this._polyline.positions = [this._polyline.positions[0], newPosition];

        this._heightOffset = value;
      },
    },

    /**
     * Gets or sets whether the anchor line is displayed.
     * <p>
     * Only applied when <code>heightOffset</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Boolean}
     */
    anchorLineEnabled: {
      get: function () {
        return this._polyline.show;
      },
      set: function (value) {
        this._polyline.show = value;
      },
    },

    /**
     * Gets or sets the color for the anchor line.
     * <p>
     * Only applied when <code>heightOffset</code> is defined.
     * </p>
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Color}
     */
    anchorLineColor: {
      get: function () {
        return this._polyline.material.uniforms.color;
      },
      set: function (value) {
        this._polyline.material.uniforms.color = Color.clone(
          value,
          this._polyline.material.uniforms.color
        );
      },
    },

    /**
     * Gets or sets the image of this feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {String}
     */
    image: {
      get: function () {
        return this._billboardImage;
      },
      set: function (value) {
        var imageChanged = this._billboardImage !== value;
        this._billboardImage = value;
        if (imageChanged) {
          setBillboardImage(this);
        }
      },
    },

    /**
     * Gets or sets the distance where depth testing will be disabled.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Number}
     */
    disableDepthTestDistance: {
      get: function () {
        return this._label.disableDepthTestDistance;
      },
      set: function (value) {
        this._label.disableDepthTestDistance = value;
        this._billboard.disableDepthTestDistance = value;
      },
    },

    /**
     * Gets or sets the horizontal origin of this point, which determines if the point is
     * to the left, center, or right of its anchor position.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {HorizontalOrigin}
     */
    horizontalOrigin: {
      get: function () {
        return this._billboard.horizontalOrigin;
      },
      set: function (value) {
        this._billboard.horizontalOrigin = value;
      },
    },

    /**
     * Gets or sets the vertical origin of this point, which determines if the point is
     * to the bottom, center, or top of its anchor position.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {VerticalOrigin}
     */
    verticalOrigin: {
      get: function () {
        return this._billboard.verticalOrigin;
      },
      set: function (value) {
        this._billboard.verticalOrigin = value;
      },
    },

    /**
     * Gets or sets the horizontal origin of this point's text, which determines if the point's text is
     * to the left, center, or right of its anchor position.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {HorizontalOrigin}
     */
    labelHorizontalOrigin: {
      get: function () {
        return this._label.horizontalOrigin;
      },
      set: function (value) {
        this._label.horizontalOrigin = value;
      },
    },

    /**
     * Get or sets the vertical origin of this point's text, which determines if the point's text is
     * to the bottom, center, top, or baseline of it's anchor point.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {VerticalOrigin}
     */
    labelVerticalOrigin: {
      get: function () {
        return this._label.verticalOrigin;
      },
      set: function (value) {
        this._label.verticalOrigin = value;
      },
    },

    /**
     * Gets the content of the tile containing the feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Cesium3DTileContent}
     *
     * @readonly
     * @private
     */
    content: {
      get: function () {
        return this._content;
      },
    },

    /**
     * Gets the tileset containing the feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Cesium3DTileset}
     *
     * @readonly
     */
    tileset: {
      get: function () {
        return this._content.tileset;
      },
    },

    /**
     * All objects returned by {@link Scene#pick} have a <code>primitive</code> property. This returns
     * the tileset containing the feature.
     *
     * @memberof Cesium3DTilePointFeature.prototype
     *
     * @type {Cesium3DTileset}
     *
     * @readonly
     */
    primitive: {
      get: function () {
        return this._content.tileset;
      },
    },

    /**
     * @private
     */
    pickIds: {
      get: function () {
        var ids = this._pickIds;
        ids[0] = this._billboard.pickId;
        ids[1] = this._label.pickId;
        ids[2] = this._polyline.pickId;
        return ids;
      },
    },
  });

  Cesium3DTilePointFeature.defaultColor = Color.WHITE;
  Cesium3DTilePointFeature.defaultPointOutlineColor = Color.BLACK;
  Cesium3DTilePointFeature.defaultPointOutlineWidth = 0.0;
  Cesium3DTilePointFeature.defaultPointSize = 8.0;

  function setBillboardImage(feature) {
    var b = feature._billboard;
    if (defined(feature._billboardImage) && feature._billboardImage !== b.image) {
      b.image = feature._billboardImage;
      return;
    }

    if (defined(feature._billboardImage)) {
      return;
    }

    var newColor = defaultValue(
      feature._color,
      Cesium3DTilePointFeature.defaultColor
    );
    var newOutlineColor = defaultValue(
      feature._pointOutlineColor,
      Cesium3DTilePointFeature.defaultPointOutlineColor
    );
    var newOutlineWidth = defaultValue(
      feature._pointOutlineWidth,
      Cesium3DTilePointFeature.defaultPointOutlineWidth
    );
    var newPointSize = defaultValue(
      feature._pointSize,
      Cesium3DTilePointFeature.defaultPointSize
    );

    var currentColor = feature._billboardColor;
    var currentOutlineColor = feature._billboardOutlineColor;
    var currentOutlineWidth = feature._billboardOutlineWidth;
    var currentPointSize = feature._billboardSize;

    if (
      Color.equals(newColor, currentColor) &&
      Color.equals(newOutlineColor, currentOutlineColor) &&
      newOutlineWidth === currentOutlineWidth &&
      newPointSize === currentPointSize
    ) {
      return;
    }

    feature._billboardColor = Color.clone(newColor, feature._billboardColor);
    feature._billboardOutlineColor = Color.clone(
      newOutlineColor,
      feature._billboardOutlineColor
    );
    feature._billboardOutlineWidth = newOutlineWidth;
    feature._billboardSize = newPointSize;

    var centerAlpha = newColor.alpha;
    var cssColor = newColor.toCssColorString();
    var cssOutlineColor = newOutlineColor.toCssColorString();
    var textureId = JSON.stringify([
      cssColor,
      newPointSize,
      cssOutlineColor,
      newOutlineWidth,
    ]);

    b.setImage(
      textureId,
      createBillboardPointCallback(
        centerAlpha,
        cssColor,
        cssOutlineColor,
        newOutlineWidth,
        newPointSize
      )
    );
  }

  /**
   * Returns whether the feature contains this property. This includes properties from this feature's
   * class and inherited classes when using a batch table hierarchy.
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/extensions/3DTILES_batch_table_hierarchy}
   *
   * @param {String} name The case-sensitive name of the property.
   * @returns {Boolean} Whether the feature contains this property.
   */
  Cesium3DTilePointFeature.prototype.hasProperty = function (name) {
    return this._content.batchTable.hasProperty(this._batchId, name);
  };

  /**
   * Returns an array of property names for the feature. This includes properties from this feature's
   * class and inherited classes when using a batch table hierarchy.
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/extensions/3DTILES_batch_table_hierarchy}
   *
   * @param {String[]} [results] An array into which to store the results.
   * @returns {String[]} The names of the feature's properties.
   */
  Cesium3DTilePointFeature.prototype.getPropertyNames = function (results) {
    return this._content.batchTable.getPropertyNames(this._batchId, results);
  };

  /**
   * Returns a copy of the value of the feature's property with the given name. This includes properties from this feature's
   * class and inherited classes when using a batch table hierarchy.
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/extensions/3DTILES_batch_table_hierarchy}
   *
   * @param {String} name The case-sensitive name of the property.
   * @returns {*} The value of the property or <code>undefined</code> if the property does not exist.
   *
   * @example
   * // Display all the properties for a feature in the console log.
   * var propertyNames = feature.getPropertyNames();
   * var length = propertyNames.length;
   * for (var i = 0; i < length; ++i) {
   *     var propertyName = propertyNames[i];
   *     console.log(propertyName + ': ' + feature.getProperty(propertyName));
   * }
   */
  Cesium3DTilePointFeature.prototype.getProperty = function (name) {
    return this._content.batchTable.getProperty(this._batchId, name);
  };

  /**
   * Sets the value of the feature's property with the given name.
   * <p>
   * If a property with the given name doesn't exist, it is created.
   * </p>
   *
   * @param {String} name The case-sensitive name of the property.
   * @param {*} value The value of the property that will be copied.
   *
   * @exception {DeveloperError} Inherited batch table hierarchy property is read only.
   *
   * @example
   * var height = feature.getProperty('Height'); // e.g., the height of a building
   *
   * @example
   * var name = 'clicked';
   * if (feature.getProperty(name)) {
   *     console.log('already clicked');
   * } else {
   *     feature.setProperty(name, true);
   *     console.log('first click');
   * }
   */
  Cesium3DTilePointFeature.prototype.setProperty = function (name, value) {
    this._content.batchTable.setProperty(this._batchId, name, value);

    // PERFORMANCE_IDEA: Probably overkill, but maybe only mark the tile dirty if the
    // property is in one of the style's expressions or - if it can be done quickly -
    // if the new property value changed the result of an expression.
    this._content.featurePropertiesDirty = true;
  };

  /**
   * Returns whether the feature's class name equals <code>className</code>. Unlike {@link Cesium3DTileFeature#isClass}
   * this function only checks the feature's exact class and not inherited classes.
   * <p>
   * This function returns <code>false</code> if no batch table hierarchy is present.
   * </p>
   *
   * @param {String} className The name to check against.
   * @returns {Boolean} Whether the feature's class name equals <code>className</code>
   *
   * @private
   */
  Cesium3DTilePointFeature.prototype.isExactClass = function (className) {
    return this._content.batchTable.isExactClass(this._batchId, className);
  };

  /**
   * Returns whether the feature's class or any inherited classes are named <code>className</code>.
   * <p>
   * This function returns <code>false</code> if no batch table hierarchy is present.
   * </p>
   *
   * @param {String} className The name to check against.
   * @returns {Boolean} Whether the feature's class or inherited classes are named <code>className</code>
   *
   * @private
   */
  Cesium3DTilePointFeature.prototype.isClass = function (className) {
    return this._content.batchTable.isClass(this._batchId, className);
  };

  /**
   * Returns the feature's class name.
   * <p>
   * This function returns <code>undefined</code> if no batch table hierarchy is present.
   * </p>
   *
   * @returns {String} The feature's class name.
   *
   * @private
   */
  Cesium3DTilePointFeature.prototype.getExactClassName = function () {
    return this._content.batchTable.getExactClassName(this._batchId);
  };

  /*
  * https://github.com/dy/bitmap-sdf
  * Calculate SDF for image/bitmap/bw data
  * This project is a fork of MapBox's TinySDF that works directly on an input Canvas instead of generating the glyphs themselves.
  */

      var INF = 1e20;

      function clamp(value, min, max) {
          return min < max
              ? (value < min ? min : value > max ? max : value)
              : (value < max ? max : value > min ? min : value)
      }

      function calcSDF(src, options) {
          if (!options) options = {};

          var cutoff = options.cutoff == null ? 0.25 : options.cutoff;
          var radius = options.radius == null ? 8 : options.radius;
          var channel = options.channel || 0;
          var w, h, size, data, intData, stride, ctx, canvas, imgData, i, l;

          // handle image container
          if (ArrayBuffer.isView(src) || Array.isArray(src)) {
              if (!options.width || !options.height) throw Error('For raw data width and height should be provided by options')
              w = options.width, h = options.height;
              data = src;

              if (!options.stride) stride = Math.floor(src.length / w / h);
              else stride = options.stride;
          }
          else {
              if (window.HTMLCanvasElement && src instanceof window.HTMLCanvasElement) {
                  canvas = src;
                  ctx = canvas.getContext('2d');
                  w = canvas.width, h = canvas.height;
                  imgData = ctx.getImageData(0, 0, w, h);
                  data = imgData.data;
                  stride = 4;
              }
              else if (window.CanvasRenderingContext2D && src instanceof window.CanvasRenderingContext2D) {
                  canvas = src.canvas;
                  ctx = src;
                  w = canvas.width, h = canvas.height;
                  imgData = ctx.getImageData(0, 0, w, h);
                  data = imgData.data;
                  stride = 4;
              }
              else if (window.ImageData && src instanceof window.ImageData) {
                  imgData = src;
                  w = src.width, h = src.height;
                  data = imgData.data;
                  stride = 4;
              }
          }

          size = Math.max(w, h);

          //convert int data to floats
          if ((window.Uint8ClampedArray && data instanceof window.Uint8ClampedArray) || (window.Uint8Array && data instanceof window.Uint8Array)) {
              intData = data;
              data = Array(w * h);

              for (i = 0, l = intData.length; i < l; i++) {
                  data[i] = intData[i * stride + channel] / 255;
              }
          }
          else {
              if (stride !== 1) throw Error('Raw data can have only 1 value per pixel')
          }

          // temporary arrays for the distance transform
          var gridOuter = Array(w * h);
          var gridInner = Array(w * h);
          var f = Array(size);
          var d = Array(size);
          var z = Array(size + 1);
          var v = Array(size);

          for (i = 0, l = w * h; i < l; i++) {
              var a = data[i];
              gridOuter[i] = a === 1 ? 0 : a === 0 ? INF : Math.pow(Math.max(0, 0.5 - a), 2);
              gridInner[i] = a === 1 ? INF : a === 0 ? 0 : Math.pow(Math.max(0, a - 0.5), 2);
          }

          edt(gridOuter, w, h, f, d, v, z);
          edt(gridInner, w, h, f, d, v, z);

          var dist = window.Float32Array ? new Float32Array(w * h) : new Array(w * h);

          for (i = 0, l = w * h; i < l; i++) {
              dist[i] = clamp(1 - ((gridOuter[i] - gridInner[i]) / radius + cutoff), 0, 1);
          }

          return dist
      }

      // 2D Euclidean distance transform by Felzenszwalb & Huttenlocher https://cs.brown.edu/~pff/dt/
      function edt(data, width, height, f, d, v, z) {
          for (var x = 0; x < width; x++) {
              for (var y = 0; y < height; y++) {
                  f[y] = data[y * width + x];
              }
              edt1d(f, d, v, z, height);
              for (y = 0; y < height; y++) {
                  data[y * width + x] = d[y];
              }
          }
          for (y = 0; y < height; y++) {
              for (x = 0; x < width; x++) {
                  f[x] = data[y * width + x];
              }
              edt1d(f, d, v, z, width);
              for (x = 0; x < width; x++) {
                  data[y * width + x] = Math.sqrt(d[x]);
              }
          }
      }

      // 1D squared distance transform
      function edt1d(f, d, v, z, n) {
          v[0] = 0;
          z[0] = -INF;
          z[1] = +INF;

          for (var q = 1, k = 0; q < n; q++) {
              var s = ((f[q] + q * q) - (f[v[k]] + v[k] * v[k])) / (2 * q - 2 * v[k]);
              while (s <= z[k]) {
                  k--;
                  s = ((f[q] + q * q) - (f[v[k]] + v[k] * v[k])) / (2 * q - 2 * v[k]);
              }
              k++;
              v[k] = q;
              z[k] = s;
              z[k + 1] = +INF;
          }

          for (q = 0, k = 0; q < n; q++) {
              while (z[k + 1] < q) k++;
              d[q] = (q - v[k]) * (q - v[k]) + f[v[k]];
          }
      }

  /**
   * Describes how to draw a label.
   *
   * @enum {Number}
   *
   * @see Label#style
   */
  var LabelStyle = {
    /**
     * Fill the text of the label, but do not outline.
     *
     * @type {Number}
     * @constant
     */
    FILL: 0,

    /**
     * Outline the text of the label, but do not fill.
     *
     * @type {Number}
     * @constant
     */
    OUTLINE: 1,

    /**
     * Fill and outline the text of the label.
     *
     * @type {Number}
     * @constant
     */
    FILL_AND_OUTLINE: 2,
  };
  var LabelStyle$1 = Object.freeze(LabelStyle);

  var fontInfoCache = {};
  var fontInfoCacheLength = 0;
  var fontInfoCacheMaxSize = 256;
  var defaultBackgroundColor = new Color(0.165, 0.165, 0.165, 0.8);
  var defaultBackgroundPadding = new Cartesian2(7, 5);

  var textTypes = Object.freeze({
    LTR: 0,
    RTL: 1,
    WEAK: 2,
    BRACKETS: 3,
  });

  function rebindAllGlyphs(label) {
    if (!label._rebindAllGlyphs && !label._repositionAllGlyphs) {
      // only push label if it's not already been marked dirty
      label._labelCollection._labelsToUpdate.push(label);
    }
    label._rebindAllGlyphs = true;
  }

  function repositionAllGlyphs(label) {
    if (!label._rebindAllGlyphs && !label._repositionAllGlyphs) {
      // only push label if it's not already been marked dirty
      label._labelCollection._labelsToUpdate.push(label);
    }
    label._repositionAllGlyphs = true;
  }

  function getCSSValue$1(element, property) {
    return document.defaultView
      .getComputedStyle(element, null)
      .getPropertyValue(property);
  }

  function parseFont(label) {
    var fontInfo = fontInfoCache[label._font];
    if (!defined(fontInfo)) {
      var div = document.createElement("div");
      div.style.position = "absolute";
      div.style.opacity = 0;
      div.style.font = label._font;
      document.body.appendChild(div);

      fontInfo = {
        family: getCSSValue$1(div, "font-family"),
        size: getCSSValue$1(div, "font-size").replace("px", ""),
        style: getCSSValue$1(div, "font-style"),
        weight: getCSSValue$1(div, "font-weight"),
      };

      document.body.removeChild(div);
      if (fontInfoCacheLength < fontInfoCacheMaxSize) {
        fontInfoCache[label._font] = fontInfo;
        fontInfoCacheLength++;
      }
    }
    label._fontFamily = fontInfo.family;
    label._fontSize = fontInfo.size;
    label._fontStyle = fontInfo.style;
    label._fontWeight = fontInfo.weight;
  }

  /**
   * A Label draws viewport-aligned text positioned in the 3D scene.  This constructor
   * should not be used directly, instead create labels by calling {@link LabelCollection#add}.
   *
   * @alias Label
   * @internalConstructor
   * @class
   *
   * @exception {DeveloperError} translucencyByDistance.far must be greater than translucencyByDistance.near
   * @exception {DeveloperError} pixelOffsetScaleByDistance.far must be greater than pixelOffsetScaleByDistance.near
   * @exception {DeveloperError} distanceDisplayCondition.far must be greater than distanceDisplayCondition.near
   *
   * @see LabelCollection
   * @see LabelCollection#add
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Labels.html|Cesium Sandcastle Labels Demo}
   */
  function Label(options, labelCollection) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (
      defined(options.disableDepthTestDistance) &&
      options.disableDepthTestDistance < 0.0
    ) {
      throw new DeveloperError(
        "disableDepthTestDistance must be greater than 0.0."
      );
    }
    //>>includeEnd('debug');

    var translucencyByDistance = options.translucencyByDistance;
    var pixelOffsetScaleByDistance = options.pixelOffsetScaleByDistance;
    var scaleByDistance = options.scaleByDistance;
    var distanceDisplayCondition = options.distanceDisplayCondition;
    if (defined(translucencyByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (translucencyByDistance.far <= translucencyByDistance.near) {
        throw new DeveloperError(
          "translucencyByDistance.far must be greater than translucencyByDistance.near."
        );
      }
      //>>includeEnd('debug');
      translucencyByDistance = NearFarScalar.clone(translucencyByDistance);
    }
    if (defined(pixelOffsetScaleByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (pixelOffsetScaleByDistance.far <= pixelOffsetScaleByDistance.near) {
        throw new DeveloperError(
          "pixelOffsetScaleByDistance.far must be greater than pixelOffsetScaleByDistance.near."
        );
      }
      //>>includeEnd('debug');
      pixelOffsetScaleByDistance = NearFarScalar.clone(
        pixelOffsetScaleByDistance
      );
    }
    if (defined(scaleByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (scaleByDistance.far <= scaleByDistance.near) {
        throw new DeveloperError(
          "scaleByDistance.far must be greater than scaleByDistance.near."
        );
      }
      //>>includeEnd('debug');
      scaleByDistance = NearFarScalar.clone(scaleByDistance);
    }
    if (defined(distanceDisplayCondition)) {
      //>>includeStart('debug', pragmas.debug);
      if (distanceDisplayCondition.far <= distanceDisplayCondition.near) {
        throw new DeveloperError(
          "distanceDisplayCondition.far must be greater than distanceDisplayCondition.near."
        );
      }
      //>>includeEnd('debug');
      distanceDisplayCondition = DistanceDisplayCondition.clone(
        distanceDisplayCondition
      );
    }

    this._renderedText = undefined;
    this._text = undefined;
    this._show = defaultValue(options.show, true);
    this._font = defaultValue(options.font, "30px sans-serif");
    this._fillColor = Color.clone(defaultValue(options.fillColor, Color.WHITE));
    this._outlineColor = Color.clone(
      defaultValue(options.outlineColor, Color.BLACK)
    );
    this._outlineWidth = defaultValue(options.outlineWidth, 1.0);
    this._showBackground = defaultValue(options.showBackground, false);
    this._backgroundColor = Color.clone(
      defaultValue(options.backgroundColor, defaultBackgroundColor)
    );
    this._backgroundPadding = Cartesian2.clone(
      defaultValue(options.backgroundPadding, defaultBackgroundPadding)
    );
    this._style = defaultValue(options.style, LabelStyle$1.FILL);
    this._verticalOrigin = defaultValue(
      options.verticalOrigin,
      VerticalOrigin$1.BASELINE
    );
    this._horizontalOrigin = defaultValue(
      options.horizontalOrigin,
      HorizontalOrigin$1.LEFT
    );
    this._pixelOffset = Cartesian2.clone(
      defaultValue(options.pixelOffset, Cartesian2.ZERO)
    );
    this._eyeOffset = Cartesian3.clone(
      defaultValue(options.eyeOffset, Cartesian3.ZERO)
    );
    this._position = Cartesian3.clone(
      defaultValue(options.position, Cartesian3.ZERO)
    );
    this._scale = defaultValue(options.scale, 1.0);
    this._id = options.id;
    this._translucencyByDistance = translucencyByDistance;
    this._pixelOffsetScaleByDistance = pixelOffsetScaleByDistance;
    this._scaleByDistance = scaleByDistance;
    this._heightReference = defaultValue(
      options.heightReference,
      HeightReference$1.NONE
    );
    this._distanceDisplayCondition = distanceDisplayCondition;
    this._disableDepthTestDistance = options.disableDepthTestDistance;

    this._labelCollection = labelCollection;
    this._glyphs = [];
    this._backgroundBillboard = undefined;
    this._batchIndex = undefined; // Used only by Vector3DTilePoints and BillboardCollection

    this._rebindAllGlyphs = true;
    this._repositionAllGlyphs = true;

    this._actualClampedPosition = undefined;
    this._removeCallbackFunc = undefined;
    this._mode = undefined;

    this._clusterShow = true;

    this.text = defaultValue(options.text, "");

    this._relativeSize = 1.0;

    parseFont(this);

    this._updateClamping();
  }

  Object.defineProperties(Label.prototype, {
    /**
     * Determines if this label will be shown.  Use this to hide or show a label, instead
     * of removing it and re-adding it to the collection.
     * @memberof Label.prototype
     * @type {Boolean}
     * @default true
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._show !== value) {
          this._show = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var billboard = glyphs[i].billboard;
            if (defined(billboard)) {
              billboard.show = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.show = value;
          }
        }
      },
    },

    /**
     * Gets or sets the Cartesian position of this label.
     * @memberof Label.prototype
     * @type {Cartesian3}
     */
    position: {
      get: function () {
        return this._position;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var position = this._position;
        if (!Cartesian3.equals(position, value)) {
          Cartesian3.clone(value, position);

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var billboard = glyphs[i].billboard;
            if (defined(billboard)) {
              billboard.position = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.position = value;
          }

          this._updateClamping();
        }
      },
    },

    /**
     * Gets or sets the height reference of this billboard.
     * @memberof Label.prototype
     * @type {HeightReference}
     * @default HeightReference.NONE
     */
    heightReference: {
      get: function () {
        return this._heightReference;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (value !== this._heightReference) {
          this._heightReference = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var billboard = glyphs[i].billboard;
            if (defined(billboard)) {
              billboard.heightReference = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.heightReference = value;
          }

          repositionAllGlyphs(this);

          this._updateClamping();
        }
      },
    },

    /**
     * Gets or sets the text of this label.
     * @memberof Label.prototype
     * @type {String}
     */
    text: {
      get: function () {
        return this._text;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._text !== value) {
          this._text = value;
          this._renderedText = Label.enableRightToLeftDetection
            ? reverseRtl(value)
            : value;
          rebindAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the font used to draw this label. Fonts are specified using the same syntax as the CSS 'font' property.
     * @memberof Label.prototype
     * @type {String}
     * @default '30px sans-serif'
     * @see {@link http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#text-styles|HTML canvas 2D context text styles}
     */
    font: {
      get: function () {
        return this._font;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._font !== value) {
          this._font = value;
          rebindAllGlyphs(this);
          parseFont(this);
        }
      },
    },

    /**
     * Gets or sets the fill color of this label.
     * @memberof Label.prototype
     * @type {Color}
     * @default Color.WHITE
     * @see {@link http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#fill-and-stroke-styles|HTML canvas 2D context fill and stroke styles}
     */
    fillColor: {
      get: function () {
        return this._fillColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var fillColor = this._fillColor;
        if (!Color.equals(fillColor, value)) {
          Color.clone(value, fillColor);
          rebindAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the outline color of this label.
     * @memberof Label.prototype
     * @type {Color}
     * @default Color.BLACK
     * @see {@link http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#fill-and-stroke-styles|HTML canvas 2D context fill and stroke styles}
     */
    outlineColor: {
      get: function () {
        return this._outlineColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var outlineColor = this._outlineColor;
        if (!Color.equals(outlineColor, value)) {
          Color.clone(value, outlineColor);
          rebindAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the outline width of this label.
     * @memberof Label.prototype
     * @type {Number}
     * @default 1.0
     * @see {@link http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#fill-and-stroke-styles|HTML canvas 2D context fill and stroke styles}
     */
    outlineWidth: {
      get: function () {
        return this._outlineWidth;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._outlineWidth !== value) {
          this._outlineWidth = value;
          rebindAllGlyphs(this);
        }
      },
    },

    /**
     * Determines if a background behind this label will be shown.
     * @memberof Label.prototype
     * @default false
     * @type {Boolean}
     */
    showBackground: {
      get: function () {
        return this._showBackground;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._showBackground !== value) {
          this._showBackground = value;
          rebindAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the background color of this label.
     * @memberof Label.prototype
     * @type {Color}
     * @default new Color(0.165, 0.165, 0.165, 0.8)
     */
    backgroundColor: {
      get: function () {
        return this._backgroundColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var backgroundColor = this._backgroundColor;
        if (!Color.equals(backgroundColor, value)) {
          Color.clone(value, backgroundColor);

          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.color = backgroundColor;
          }
        }
      },
    },

    /**
     * Gets or sets the background padding, in pixels, of this label.  The <code>x</code> value
     * controls horizontal padding, and the <code>y</code> value controls vertical padding.
     * @memberof Label.prototype
     * @type {Cartesian2}
     * @default new Cartesian2(7, 5)
     */
    backgroundPadding: {
      get: function () {
        return this._backgroundPadding;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var backgroundPadding = this._backgroundPadding;
        if (!Cartesian2.equals(backgroundPadding, value)) {
          Cartesian2.clone(value, backgroundPadding);
          repositionAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the style of this label.
     * @memberof Label.prototype
     * @type {LabelStyle}
     * @default LabelStyle.FILL
     */
    style: {
      get: function () {
        return this._style;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._style !== value) {
          this._style = value;
          rebindAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the pixel offset in screen space from the origin of this label.  This is commonly used
     * to align multiple labels and billboards at the same position, e.g., an image and text.  The
     * screen space origin is the top, left corner of the canvas; <code>x</code> increases from
     * left to right, and <code>y</code> increases from top to bottom.
     * <br /><br />
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><code>default</code><br/><img src='Images/Label.setPixelOffset.default.png' width='250' height='188' /></td>
     * <td align='center'><code>l.pixeloffset = new Cartesian2(25, 75);</code><br/><img src='Images/Label.setPixelOffset.x50y-25.png' width='250' height='188' /></td>
     * </tr></table>
     * The label's origin is indicated by the yellow point.
     * </div>
     * @memberof Label.prototype
     * @type {Cartesian2}
     * @default Cartesian2.ZERO
     */
    pixelOffset: {
      get: function () {
        return this._pixelOffset;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var pixelOffset = this._pixelOffset;
        if (!Cartesian2.equals(pixelOffset, value)) {
          Cartesian2.clone(value, pixelOffset);

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.pixelOffset = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.pixelOffset = value;
          }
        }
      },
    },

    /**
     * Gets or sets near and far translucency properties of a Label based on the Label's distance from the camera.
     * A label's translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the label's translucency remains clamped to the nearest bound.  If undefined,
     * translucencyByDistance will be disabled.
     * @memberof Label.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a label's translucencyByDistance to 1.0 when the
     * // camera is 1500 meters from the label and disappear as
     * // the camera distance approaches 8.0e6 meters.
     * text.translucencyByDistance = new Cesium.NearFarScalar(1.5e2, 1.0, 8.0e6, 0.0);
     *
     * @example
     * // Example 2.
     * // disable translucency by distance
     * text.translucencyByDistance = undefined;
     */
    translucencyByDistance: {
      get: function () {
        return this._translucencyByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var translucencyByDistance = this._translucencyByDistance;
        if (!NearFarScalar.equals(translucencyByDistance, value)) {
          this._translucencyByDistance = NearFarScalar.clone(
            value,
            translucencyByDistance
          );

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.translucencyByDistance = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.translucencyByDistance = value;
          }
        }
      },
    },

    /**
     * Gets or sets near and far pixel offset scaling properties of a Label based on the Label's distance from the camera.
     * A label's pixel offset will be scaled between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the label's pixel offset scaling remains clamped to the nearest bound.  If undefined,
     * pixelOffsetScaleByDistance will be disabled.
     * @memberof Label.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a label's pixel offset scale to 0.0 when the
     * // camera is 1500 meters from the label and scale pixel offset to 10.0 pixels
     * // in the y direction the camera distance approaches 8.0e6 meters.
     * text.pixelOffset = new Cesium.Cartesian2(0.0, 1.0);
     * text.pixelOffsetScaleByDistance = new Cesium.NearFarScalar(1.5e2, 0.0, 8.0e6, 10.0);
     *
     * @example
     * // Example 2.
     * // disable pixel offset by distance
     * text.pixelOffsetScaleByDistance = undefined;
     */
    pixelOffsetScaleByDistance: {
      get: function () {
        return this._pixelOffsetScaleByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var pixelOffsetScaleByDistance = this._pixelOffsetScaleByDistance;
        if (!NearFarScalar.equals(pixelOffsetScaleByDistance, value)) {
          this._pixelOffsetScaleByDistance = NearFarScalar.clone(
            value,
            pixelOffsetScaleByDistance
          );

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.pixelOffsetScaleByDistance = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.pixelOffsetScaleByDistance = value;
          }
        }
      },
    },

    /**
     * Gets or sets near and far scaling properties of a Label based on the label's distance from the camera.
     * A label's scale will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the label's scale remains clamped to the nearest bound.  If undefined,
     * scaleByDistance will be disabled.
     * @memberof Label.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a label's scaleByDistance to scale by 1.5 when the
     * // camera is 1500 meters from the label and disappear as
     * // the camera distance approaches 8.0e6 meters.
     * label.scaleByDistance = new Cesium.NearFarScalar(1.5e2, 1.5, 8.0e6, 0.0);
     *
     * @example
     * // Example 2.
     * // disable scaling by distance
     * label.scaleByDistance = undefined;
     */
    scaleByDistance: {
      get: function () {
        return this._scaleByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var scaleByDistance = this._scaleByDistance;
        if (!NearFarScalar.equals(scaleByDistance, value)) {
          this._scaleByDistance = NearFarScalar.clone(value, scaleByDistance);

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.scaleByDistance = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.scaleByDistance = value;
          }
        }
      },
    },

    /**
     * Gets and sets the 3D Cartesian offset applied to this label in eye coordinates.  Eye coordinates is a left-handed
     * coordinate system, where <code>x</code> points towards the viewer's right, <code>y</code> points up, and
     * <code>z</code> points into the screen.  Eye coordinates use the same scale as world and model coordinates,
     * which is typically meters.
     * <br /><br />
     * An eye offset is commonly used to arrange multiple label or objects at the same position, e.g., to
     * arrange a label above its corresponding 3D model.
     * <br /><br />
     * Below, the label is positioned at the center of the Earth but an eye offset makes it always
     * appear on top of the Earth regardless of the viewer's or Earth's orientation.
     * <br /><br />
     * <div align='center'>
     * <table border='0' cellpadding='5'><tr>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.one.png' width='250' height='188' /></td>
     * <td align='center'><img src='Images/Billboard.setEyeOffset.two.png' width='250' height='188' /></td>
     * </tr></table>
     * <code>l.eyeOffset = new Cartesian3(0.0, 8000000.0, 0.0);</code><br /><br />
     * </div>
     * @memberof Label.prototype
     * @type {Cartesian3}
     * @default Cartesian3.ZERO
     */
    eyeOffset: {
      get: function () {
        return this._eyeOffset;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var eyeOffset = this._eyeOffset;
        if (!Cartesian3.equals(eyeOffset, value)) {
          Cartesian3.clone(value, eyeOffset);

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.eyeOffset = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.eyeOffset = value;
          }
        }
      },
    },

    /**
     * Gets or sets the horizontal origin of this label, which determines if the label is drawn
     * to the left, center, or right of its anchor position.
     * <br /><br />
     * <div align='center'>
     * <img src='Images/Billboard.setHorizontalOrigin.png' width='648' height='196' /><br />
     * </div>
     * @memberof Label.prototype
     * @type {HorizontalOrigin}
     * @default HorizontalOrigin.LEFT
     * @example
     * // Use a top, right origin
     * l.horizontalOrigin = Cesium.HorizontalOrigin.RIGHT;
     * l.verticalOrigin = Cesium.VerticalOrigin.TOP;
     */
    horizontalOrigin: {
      get: function () {
        return this._horizontalOrigin;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._horizontalOrigin !== value) {
          this._horizontalOrigin = value;
          repositionAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the vertical origin of this label, which determines if the label is
     * to the above, below, or at the center of its anchor position.
     * <br /><br />
     * <div align='center'>
     * <img src='Images/Billboard.setVerticalOrigin.png' width='695' height='175' /><br />
     * </div>
     * @memberof Label.prototype
     * @type {VerticalOrigin}
     * @default VerticalOrigin.BASELINE
     * @example
     * // Use a top, right origin
     * l.horizontalOrigin = Cesium.HorizontalOrigin.RIGHT;
     * l.verticalOrigin = Cesium.VerticalOrigin.TOP;
     */
    verticalOrigin: {
      get: function () {
        return this._verticalOrigin;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._verticalOrigin !== value) {
          this._verticalOrigin = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.verticalOrigin = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.verticalOrigin = value;
          }

          repositionAllGlyphs(this);
        }
      },
    },

    /**
     * Gets or sets the uniform scale that is multiplied with the label's size in pixels.
     * A scale of <code>1.0</code> does not change the size of the label; a scale greater than
     * <code>1.0</code> enlarges the label; a positive scale less than <code>1.0</code> shrinks
     * the label.
     * <br /><br />
     * Applying a large scale value may pixelate the label.  To make text larger without pixelation,
     * use a larger font size when calling {@link Label#font} instead.
     * <br /><br />
     * <div align='center'>
     * <img src='Images/Label.setScale.png' width='400' height='300' /><br/>
     * From left to right in the above image, the scales are <code>0.5</code>, <code>1.0</code>,
     * and <code>2.0</code>.
     * </div>
     * @memberof Label.prototype
     * @type {Number}
     * @default 1.0
     */
    scale: {
      get: function () {
        return this._scale;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._scale !== value) {
          this._scale = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.scale = value * this._relativeSize;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.scale = value * this._relativeSize;
          }

          repositionAllGlyphs(this);
        }
      },
    },

    /**
     * Gets the total scale of the label, which is the label's scale multiplied by the computed relative size
     * of the desired font compared to the generated glyph size.
     * @memberof Label.prototype
     * @type {Number}
     * @default 1.0
     */
    totalScale: {
      get: function () {
        return this._scale * this._relativeSize;
      },
    },

    /**
     * Gets or sets the condition specifying at what distance from the camera that this label will be displayed.
     * @memberof Label.prototype
     * @type {DistanceDisplayCondition}
     * @default undefined
     */
    distanceDisplayCondition: {
      get: function () {
        return this._distanceDisplayCondition;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError("far must be greater than near");
        }
        //>>includeEnd('debug');
        if (
          !DistanceDisplayCondition.equals(value, this._distanceDisplayCondition)
        ) {
          this._distanceDisplayCondition = DistanceDisplayCondition.clone(
            value,
            this._distanceDisplayCondition
          );

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.distanceDisplayCondition = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.distanceDisplayCondition = value;
          }
        }
      },
    },

    /**
     * Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
     * When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.
     * @memberof Label.prototype
     * @type {Number}
     */
    disableDepthTestDistance: {
      get: function () {
        return this._disableDepthTestDistance;
      },
      set: function (value) {
        if (this._disableDepthTestDistance !== value) {
          //>>includeStart('debug', pragmas.debug);
          if (defined(value) && value < 0.0) {
            throw new DeveloperError(
              "disableDepthTestDistance must be greater than 0.0."
            );
          }
          //>>includeEnd('debug');
          this._disableDepthTestDistance = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.disableDepthTestDistance = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.disableDepthTestDistance = value;
          }
        }
      },
    },

    /**
     * Gets or sets the user-defined value returned when the label is picked.
     * @memberof Label.prototype
     * @type {*}
     */
    id: {
      get: function () {
        return this._id;
      },
      set: function (value) {
        if (this._id !== value) {
          this._id = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.id = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.id = value;
          }
        }
      },
    },

    /**
     * @private
     */
    pickId: {
      get: function () {
        if (this._glyphs.length === 0 || !defined(this._glyphs[0].billboard)) {
          return undefined;
        }
        return this._glyphs[0].billboard.pickId;
      },
    },

    /**
     * Keeps track of the position of the label based on the height reference.
     * @memberof Label.prototype
     * @type {Cartesian3}
     * @private
     */
    _clampedPosition: {
      get: function () {
        return this._actualClampedPosition;
      },
      set: function (value) {
        this._actualClampedPosition = Cartesian3.clone(
          value,
          this._actualClampedPosition
        );

        var glyphs = this._glyphs;
        for (var i = 0, len = glyphs.length; i < len; i++) {
          var glyph = glyphs[i];
          if (defined(glyph.billboard)) {
            // Set all the private values here, because we already clamped to ground
            //  so we don't want to do it again for every glyph
            glyph.billboard._clampedPosition = value;
          }
        }
        var backgroundBillboard = this._backgroundBillboard;
        if (defined(backgroundBillboard)) {
          backgroundBillboard._clampedPosition = value;
        }
      },
    },

    /**
     * Determines whether or not this label will be shown or hidden because it was clustered.
     * @memberof Label.prototype
     * @type {Boolean}
     * @default true
     * @private
     */
    clusterShow: {
      get: function () {
        return this._clusterShow;
      },
      set: function (value) {
        if (this._clusterShow !== value) {
          this._clusterShow = value;

          var glyphs = this._glyphs;
          for (var i = 0, len = glyphs.length; i < len; i++) {
            var glyph = glyphs[i];
            if (defined(glyph.billboard)) {
              glyph.billboard.clusterShow = value;
            }
          }
          var backgroundBillboard = this._backgroundBillboard;
          if (defined(backgroundBillboard)) {
            backgroundBillboard.clusterShow = value;
          }
        }
      },
    },
  });

  Label.prototype._updateClamping = function () {
    Billboard._updateClamping(this._labelCollection, this);
  };

  /**
   * Computes the screen-space position of the label's origin, taking into account eye and pixel offsets.
   * The screen space origin is the top, left corner of the canvas; <code>x</code> increases from
   * left to right, and <code>y</code> increases from top to bottom.
   *
   * @param {Scene} scene The scene the label is in.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The screen-space position of the label.
   *
   *
   * @example
   * console.log(l.computeScreenSpacePosition(scene).toString());
   *
   * @see Label#eyeOffset
   * @see Label#pixelOffset
   */
  Label.prototype.computeScreenSpacePosition = function (scene, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian2();
    }

    var labelCollection = this._labelCollection;
    var modelMatrix = labelCollection.modelMatrix;
    var actualPosition = defined(this._actualClampedPosition)
      ? this._actualClampedPosition
      : this._position;

    var windowCoordinates = Billboard._computeScreenSpacePosition(
      modelMatrix,
      actualPosition,
      this._eyeOffset,
      this._pixelOffset,
      scene,
      result
    );
    return windowCoordinates;
  };

  /**
   * Gets a label's screen space bounding box centered around screenSpacePosition.
   * @param {Label} label The label to get the screen space bounding box for.
   * @param {Cartesian2} screenSpacePosition The screen space center of the label.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The screen space bounding box.
   *
   * @private
   */
  Label.getScreenSpaceBoundingBox = function (
    label,
    screenSpacePosition,
    result
  ) {
    var x = 0;
    var y = 0;
    var width = 0;
    var height = 0;
    var scale = label.totalScale;

    var backgroundBillboard = label._backgroundBillboard;
    if (defined(backgroundBillboard)) {
      x = screenSpacePosition.x + backgroundBillboard._translate.x;
      y = screenSpacePosition.y - backgroundBillboard._translate.y;
      width = backgroundBillboard.width * scale;
      height = backgroundBillboard.height * scale;

      if (
        label.verticalOrigin === VerticalOrigin$1.BOTTOM ||
        label.verticalOrigin === VerticalOrigin$1.BASELINE
      ) {
        y -= height;
      } else if (label.verticalOrigin === VerticalOrigin$1.CENTER) {
        y -= height * 0.5;
      }
    } else {
      x = Number.POSITIVE_INFINITY;
      y = Number.POSITIVE_INFINITY;
      var maxX = 0;
      var maxY = 0;
      var glyphs = label._glyphs;
      var length = glyphs.length;
      for (var i = 0; i < length; ++i) {
        var glyph = glyphs[i];
        var billboard = glyph.billboard;
        if (!defined(billboard)) {
          continue;
        }

        var glyphX = screenSpacePosition.x + billboard._translate.x;
        var glyphY = screenSpacePosition.y - billboard._translate.y;
        var glyphWidth = glyph.dimensions.width * scale;
        var glyphHeight = glyph.dimensions.height * scale;

        if (
          label.verticalOrigin === VerticalOrigin$1.BOTTOM ||
          label.verticalOrigin === VerticalOrigin$1.BASELINE
        ) {
          glyphY -= glyphHeight;
        } else if (label.verticalOrigin === VerticalOrigin$1.CENTER) {
          glyphY -= glyphHeight * 0.5;
        }

        if (label._verticalOrigin === VerticalOrigin$1.TOP) {
          glyphY += SDFSettings$1.PADDING * scale;
        } else if (
          label._verticalOrigin === VerticalOrigin$1.BOTTOM ||
          label._verticalOrigin === VerticalOrigin$1.BASELINE
        ) {
          glyphY -= SDFSettings$1.PADDING * scale;
        }

        x = Math.min(x, glyphX);
        y = Math.min(y, glyphY);
        maxX = Math.max(maxX, glyphX + glyphWidth);
        maxY = Math.max(maxY, glyphY + glyphHeight);
      }

      width = maxX - x;
      height = maxY - y;
    }

    if (!defined(result)) {
      result = new BoundingRectangle();
    }

    result.x = x;
    result.y = y;
    result.width = width;
    result.height = height;

    return result;
  };

  /**
   * Determines if this label equals another label.  Labels are equal if all their properties
   * are equal.  Labels in different collections can be equal.
   *
   * @param {Label} other The label to compare for equality.
   * @returns {Boolean} <code>true</code> if the labels are equal; otherwise, <code>false</code>.
   */
  Label.prototype.equals = function (other) {
    return (
      this === other ||
      (defined(other) &&
        this._show === other._show &&
        this._scale === other._scale &&
        this._outlineWidth === other._outlineWidth &&
        this._showBackground === other._showBackground &&
        this._style === other._style &&
        this._verticalOrigin === other._verticalOrigin &&
        this._horizontalOrigin === other._horizontalOrigin &&
        this._heightReference === other._heightReference &&
        this._renderedText === other._renderedText &&
        this._font === other._font &&
        Cartesian3.equals(this._position, other._position) &&
        Color.equals(this._fillColor, other._fillColor) &&
        Color.equals(this._outlineColor, other._outlineColor) &&
        Color.equals(this._backgroundColor, other._backgroundColor) &&
        Cartesian2.equals(this._backgroundPadding, other._backgroundPadding) &&
        Cartesian2.equals(this._pixelOffset, other._pixelOffset) &&
        Cartesian3.equals(this._eyeOffset, other._eyeOffset) &&
        NearFarScalar.equals(
          this._translucencyByDistance,
          other._translucencyByDistance
        ) &&
        NearFarScalar.equals(
          this._pixelOffsetScaleByDistance,
          other._pixelOffsetScaleByDistance
        ) &&
        NearFarScalar.equals(this._scaleByDistance, other._scaleByDistance) &&
        DistanceDisplayCondition.equals(
          this._distanceDisplayCondition,
          other._distanceDisplayCondition
        ) &&
        this._disableDepthTestDistance === other._disableDepthTestDistance &&
        this._id === other._id)
    );
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  Label.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Determines whether or not run the algorithm, that match the text of the label to right-to-left languages
   * @memberof Label
   * @type {Boolean}
   * @default false
   *
   * @example
   * // Example 1.
   * // Set a label's rightToLeft before init
   * Cesium.Label.enableRightToLeftDetection = true;
   * var myLabelEntity = viewer.entities.add({
   *   label: {
   *     id: 'my label',
   *     text: 'זה טקסט בעברית \n ועכשיו יורדים שורה',
   *   }
   * });
   *
   * @example
   * // Example 2.
   * var myLabelEntity = viewer.entities.add({
   *   label: {
   *     id: 'my label',
   *     text: 'English text'
   *   }
   * });
   * // Set a label's rightToLeft after init
   * Cesium.Label.enableRightToLeftDetection = true;
   * myLabelEntity.text = 'טקסט חדש';
   */
  Label.enableRightToLeftDetection = false;

  function convertTextToTypes(text, rtlChars) {
    var ltrChars = /[a-zA-Z0-9]/;
    var bracketsChars = /[()[\]{}<>]/;
    var parsedText = [];
    var word = "";
    var lastType = textTypes.LTR;
    var currentType = "";
    var textLength = text.length;
    for (var textIndex = 0; textIndex < textLength; ++textIndex) {
      var character = text.charAt(textIndex);
      if (rtlChars.test(character)) {
        currentType = textTypes.RTL;
      } else if (ltrChars.test(character)) {
        currentType = textTypes.LTR;
      } else if (bracketsChars.test(character)) {
        currentType = textTypes.BRACKETS;
      } else {
        currentType = textTypes.WEAK;
      }

      if (textIndex === 0) {
        lastType = currentType;
      }

      if (lastType === currentType && currentType !== textTypes.BRACKETS) {
        word += character;
      } else {
        if (word !== "") {
          parsedText.push({ Type: lastType, Word: word });
        }
        lastType = currentType;
        word = character;
      }
    }
    parsedText.push({ Type: currentType, Word: word });
    return parsedText;
  }

  function reverseWord(word) {
    return word.split("").reverse().join("");
  }

  function spliceWord(result, pointer, word) {
    return result.slice(0, pointer) + word + result.slice(pointer);
  }

  function reverseBrackets(bracket) {
    switch (bracket) {
      case "(":
        return ")";
      case ")":
        return "(";
      case "[":
        return "]";
      case "]":
        return "[";
      case "{":
        return "}";
      case "}":
        return "{";
      case "<":
        return ">";
      case ">":
        return "<";
    }
  }

  //To add another language, simply add its Unicode block range(s) to the below regex.
  var hebrew = "\u05D0-\u05EA";
  var arabic = "\u0600-\u06FF\u0750-\u077F\u08A0-\u08FF";
  var rtlChars = new RegExp("[" + hebrew + arabic + "]");

  /**
   *
   * @param {String} value the text to parse and reorder
   * @returns {String} the text as rightToLeft direction
   * @private
   */
  function reverseRtl(value) {
    var texts = value.split("\n");
    var result = "";
    for (var i = 0; i < texts.length; i++) {
      var text = texts[i];
      // first character of the line is a RTL character, so need to manage different cases
      var rtlDir = rtlChars.test(text.charAt(0));
      var parsedText = convertTextToTypes(text, rtlChars);

      var splicePointer = 0;
      var line = "";
      for (var wordIndex = 0; wordIndex < parsedText.length; ++wordIndex) {
        var subText = parsedText[wordIndex];
        var reverse =
          subText.Type === textTypes.BRACKETS
            ? reverseBrackets(subText.Word)
            : reverseWord(subText.Word);
        if (rtlDir) {
          if (subText.Type === textTypes.RTL) {
            line = reverse + line;
            splicePointer = 0;
          } else if (subText.Type === textTypes.LTR) {
            line = spliceWord(line, splicePointer, subText.Word);
            splicePointer += subText.Word.length;
          } else if (
            subText.Type === textTypes.WEAK ||
            subText.Type === textTypes.BRACKETS
          ) {
            // current word is weak, last one was bracket
            if (
              subText.Type === textTypes.WEAK &&
              parsedText[wordIndex - 1].Type === textTypes.BRACKETS
            ) {
              line = reverse + line;
            }
            // current word is weak or bracket, last one was rtl
            else if (parsedText[wordIndex - 1].Type === textTypes.RTL) {
              line = reverse + line;
              splicePointer = 0;
            }
            // current word is weak or bracket, there is at least one more word
            else if (parsedText.length > wordIndex + 1) {
              // next word is rtl
              if (parsedText[wordIndex + 1].Type === textTypes.RTL) {
                line = reverse + line;
                splicePointer = 0;
              } else {
                line = spliceWord(line, splicePointer, subText.Word);
                splicePointer += subText.Word.length;
              }
            }
            // current word is weak or bracket, and it the last in this line
            else {
              line = spliceWord(line, 0, reverse);
            }
          }
        }
        // ltr line, rtl word
        else if (subText.Type === textTypes.RTL) {
          line = spliceWord(line, splicePointer, reverse);
        }
        // ltr line, ltr word
        else if (subText.Type === textTypes.LTR) {
          line += subText.Word;
          splicePointer = line.length;
        }
        // ltr line, weak or bracket word
        else if (
          subText.Type === textTypes.WEAK ||
          subText.Type === textTypes.BRACKETS
        ) {
          // not first word in line
          if (wordIndex > 0) {
            // last word was rtl
            if (parsedText[wordIndex - 1].Type === textTypes.RTL) {
              // there is at least one more word
              if (parsedText.length > wordIndex + 1) {
                // next word is rtl
                if (parsedText[wordIndex + 1].Type === textTypes.RTL) {
                  line = spliceWord(line, splicePointer, reverse);
                } else {
                  line += subText.Word;
                  splicePointer = line.length;
                }
              } else {
                line += subText.Word;
              }
            } else {
              line += subText.Word;
              splicePointer = line.length;
            }
          } else {
            line += subText.Word;
            splicePointer = line.length;
          }
        }
      }

      result += line;
      if (i < texts.length - 1) {
        result += "\n";
      }
    }
    return result;
  }

  /*
  Breaks a Javascript string into individual user-perceived "characters"
  called extended grapheme clusters by implementing the Unicode UAX-29 standard, version 10.0.0
  Usage:
  var splitter = new GraphemeSplitter();
  //returns an array of strings, one string for each grapheme cluster
  var graphemes = splitter.splitGraphemes(string);
  */
  function GraphemeSplitter(){
  	var CR = 0,
  		LF = 1,
  		Control = 2,
  		Extend = 3,
  		Regional_Indicator = 4,
  		SpacingMark = 5,
  		L = 6,
  		V = 7,
  		T = 8,
  		LV = 9,
  		LVT = 10,
  		Other = 11,
  		Prepend = 12,
  		E_Base = 13,
  		E_Modifier = 14,
  		ZWJ = 15,
  		Glue_After_Zwj = 16,
  		E_Base_GAZ = 17;

  	// BreakTypes
  	var NotBreak = 0,
  		BreakStart = 1,
  		Break = 2,
  		BreakLastRegional = 3,
  		BreakPenultimateRegional = 4;

  	function isSurrogate(str, pos) {
  		return  0xd800 <= str.charCodeAt(pos) && str.charCodeAt(pos) <= 0xdbff &&
  				0xdc00 <= str.charCodeAt(pos + 1) && str.charCodeAt(pos + 1) <= 0xdfff;
  	}

  	// Private function, gets a Unicode code point from a JavaScript UTF-16 string
  	// handling surrogate pairs appropriately
  	function codePointAt(str, idx){
  		if(idx === undefined){
  			idx = 0;
  		}
  		var code = str.charCodeAt(idx);

  		// if a high surrogate
  		if (0xD800 <= code && code <= 0xDBFF &&
  			idx < str.length - 1){
  			var hi = code;
  			var low = str.charCodeAt(idx + 1);
  			if (0xDC00 <= low && low <= 0xDFFF){
  				return ((hi - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000;
  			}
  			return hi;
  		}

  		// if a low surrogate
  		if (0xDC00 <= code && code <= 0xDFFF &&
  			idx >= 1){
  			var hi = str.charCodeAt(idx - 1);
  			var low = code;
  			if (0xD800 <= hi && hi <= 0xDBFF){
  				return ((hi - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000;
  			}
  			return low;
  		}

  		//just return the char if an unmatched surrogate half or a
  		//single-char codepoint
  		return code;
  	}

  	// Private function, returns whether a break is allowed between the
  	// two given grapheme breaking classes
  	function shouldBreak(start, mid, end){
  		var all = [start].concat(mid).concat([end]);
  		var previous = all[all.length - 2];
  		var next = end;

  		// Lookahead termintor for:
  		// GB10. (E_Base | EBG) Extend* ?	E_Modifier
  		var eModifierIndex = all.lastIndexOf(E_Modifier);
  		if(eModifierIndex > 1 &&
  			all.slice(1, eModifierIndex).every(function(c){return c == Extend}) &&
  			[Extend, E_Base, E_Base_GAZ].indexOf(start) == -1){
  			return Break
  		}

  		// Lookahead termintor for:
  		// GB12. ^ (RI RI)* RI	?	RI
  		// GB13. [^RI] (RI RI)* RI	?	RI
  		var rIIndex = all.lastIndexOf(Regional_Indicator);
  		if(rIIndex > 0 &&
  			all.slice(1, rIIndex).every(function(c){return c == Regional_Indicator}) &&
  			[Prepend, Regional_Indicator].indexOf(previous) == -1) {
  			if(all.filter(function(c){return c == Regional_Indicator}).length % 2 == 1) {
  				return BreakLastRegional
  			}
  			else {
  				return BreakPenultimateRegional
  			}
  		}

  		// GB3. CR X LF
  		if(previous == CR && next == LF){
  			return NotBreak;
  		}
  		// GB4. (Control|CR|LF) ÷
  		else if(previous == Control || previous == CR || previous == LF){
  			if(next == E_Modifier && mid.every(function(c){return c == Extend})){
  				return Break
  			}
  			else {
  				return BreakStart
  			}
  		}
  		// GB5. ÷ (Control|CR|LF)
  		else if(next == Control || next == CR || next == LF){
  			return BreakStart;
  		}
  		// GB6. L X (L|V|LV|LVT)
  		else if(previous == L &&
  			(next == L || next == V || next == LV || next == LVT)){
  			return NotBreak;
  		}
  		// GB7. (LV|V) X (V|T)
  		else if((previous == LV || previous == V) &&
  			(next == V || next == T)){
  			return NotBreak;
  		}
  		// GB8. (LVT|T) X (T)
  		else if((previous == LVT || previous == T) &&
  			next == T){
  			return NotBreak;
  		}
  		// GB9. X (Extend|ZWJ)
  		else if (next == Extend || next == ZWJ){
  			return NotBreak;
  		}
  		// GB9a. X SpacingMark
  		else if(next == SpacingMark){
  			return NotBreak;
  		}
  		// GB9b. Prepend X
  		else if (previous == Prepend){
  			return NotBreak;
  		}

  		// GB10. (E_Base | EBG) Extend* ?	E_Modifier
  		var previousNonExtendIndex = all.indexOf(Extend) != -1 ? all.lastIndexOf(Extend) - 1 : all.length - 2;
  		if([E_Base, E_Base_GAZ].indexOf(all[previousNonExtendIndex]) != -1 &&
  			all.slice(previousNonExtendIndex + 1, -1).every(function(c){return c == Extend}) &&
  			next == E_Modifier){
  			return NotBreak;
  		}

  		// GB11. ZWJ ? (Glue_After_Zwj | EBG)
  		if(previous == ZWJ && [Glue_After_Zwj, E_Base_GAZ].indexOf(next) != -1) {
  			return NotBreak;
  		}

  		// GB12. ^ (RI RI)* RI ? RI
  		// GB13. [^RI] (RI RI)* RI ? RI
  		if(mid.indexOf(Regional_Indicator) != -1) {
  			return Break;
  		}
  		if(previous == Regional_Indicator && next == Regional_Indicator) {
  			return NotBreak;
  		}

  		// GB999. Any ? Any
  		return BreakStart;
  	}

  	// Returns the next grapheme break in the string after the given index
  	this.nextBreak = function(string, index){
  		if(index === undefined){
  			index = 0;
  		}
  		if(index < 0){
  			return 0;
  		}
  		if(index >= string.length - 1){
  			return string.length;
  		}
  		var prev = getGraphemeBreakProperty(codePointAt(string, index));
  		var mid = [];
  		for (var i = index + 1; i < string.length; i++) {
  			// check for already processed low surrogates
  			if(isSurrogate(string, i - 1)){
  				continue;
  			}

  			var next = getGraphemeBreakProperty(codePointAt(string, i));
  			if(shouldBreak(prev, mid, next)){
  				return i;
  			}

  			mid.push(next);
  		}
  		return string.length;
  	};

  	// Breaks the given string into an array of grapheme cluster strings
  	this.splitGraphemes = function(str){
  		var res = [];
  		var index = 0;
  		var brk;
  		while((brk = this.nextBreak(str, index)) < str.length){
  			res.push(str.slice(index, brk));
  			index = brk;
  		}
  		if(index < str.length){
  			res.push(str.slice(index));
  		}
  		return res;
  	};

  	// Returns the iterator of grapheme clusters there are in the given string
  	this.iterateGraphemes = function(str) {
  		var index = 0;
  		var res = {
  			next: (function() {
  				var value;
  				var brk;
  				if ((brk = this.nextBreak(str, index)) < str.length) {
  					value = str.slice(index, brk);
  					index = brk;
  					return { value: value, done: false };
  				}
  				if (index < str.length) {
  					value = str.slice(index);
  					index = str.length;
  					return { value: value, done: false };
  				}
  				return { value: undefined, done: true };
  			}).bind(this)
  		};
  		// ES2015 @@iterator method (iterable) for spread syntax and for...of statement
  		if (typeof Symbol !== 'undefined' && Symbol.iterator) {
  			res[Symbol.iterator] = function() {return res};
  		}
  		return res;
  	};

  	// Returns the number of grapheme clusters there are in the given string
  	this.countGraphemes = function(str){
  		var count = 0;
  		var index = 0;
  		var brk;
  		while((brk = this.nextBreak(str, index)) < str.length){
  			index = brk;
  			count++;
  		}
  		if(index < str.length){
  			count++;
  		}
  		return count;
  	};

  	//given a Unicode code point, determines this symbol's grapheme break property
  	function getGraphemeBreakProperty(code){

  		//grapheme break property for Unicode 10.0.0,
  		//taken from http://www.unicode.org/Public/10.0.0/ucd/auxiliary/GraphemeBreakProperty.txt
  		//and adapted to JavaScript rules

  		if(
  		(0x0600 <= code && code <= 0x0605) || // Cf   [6] ARABIC NUMBER SIGN..ARABIC NUMBER MARK ABOVE
  		0x06DD == code || // Cf       ARABIC END OF AYAH
  		0x070F == code || // Cf       SYRIAC ABBREVIATION MARK
  		0x08E2 == code || // Cf       ARABIC DISPUTED END OF AYAH
  		0x0D4E == code || // Lo       MALAYALAM LETTER DOT REPH
  		0x110BD == code || // Cf       KAITHI NUMBER SIGN
  		(0x111C2 <= code && code <= 0x111C3) || // Lo   [2] SHARADA SIGN JIHVAMULIYA..SHARADA SIGN UPADHMANIYA
  		0x11A3A == code || // Lo       ZANABAZAR SQUARE CLUSTER-INITIAL LETTER RA
  		(0x11A86 <= code && code <= 0x11A89) || // Lo   [4] SOYOMBO CLUSTER-INITIAL LETTER RA..SOYOMBO CLUSTER-INITIAL LETTER SA
  		0x11D46 == code // Lo       MASARAM GONDI REPHA
  		){
  			return Prepend;
  		}
  		if(
  		0x000D == code // Cc       <control-000D>
  		){
  			return CR;
  		}

  		if(
  		0x000A == code // Cc       <control-000A>
  		){
  			return LF;
  		}


  		if(
  		(0x0000 <= code && code <= 0x0009) || // Cc  [10] <control-0000>..<control-0009>
  		(0x000B <= code && code <= 0x000C) || // Cc   [2] <control-000B>..<control-000C>
  		(0x000E <= code && code <= 0x001F) || // Cc  [18] <control-000E>..<control-001F>
  		(0x007F <= code && code <= 0x009F) || // Cc  [33] <control-007F>..<control-009F>
  		0x00AD == code || // Cf       SOFT HYPHEN
  		0x061C == code || // Cf       ARABIC LETTER MARK

  		0x180E == code || // Cf       MONGOLIAN VOWEL SEPARATOR
  		0x200B == code || // Cf       ZERO WIDTH SPACE
  		(0x200E <= code && code <= 0x200F) || // Cf   [2] LEFT-TO-RIGHT MARK..RIGHT-TO-LEFT MARK
  		0x2028 == code || // Zl       LINE SEPARATOR
  		0x2029 == code || // Zp       PARAGRAPH SEPARATOR
  		(0x202A <= code && code <= 0x202E) || // Cf   [5] LEFT-TO-RIGHT EMBEDDING..RIGHT-TO-LEFT OVERRIDE
  		(0x2060 <= code && code <= 0x2064) || // Cf   [5] WORD JOINER..INVISIBLE PLUS
  		0x2065 == code || // Cn       <reserved-2065>
  		(0x2066 <= code && code <= 0x206F) || // Cf  [10] LEFT-TO-RIGHT ISOLATE..NOMINAL DIGIT SHAPES
  		(0xD800 <= code && code <= 0xDFFF) || // Cs [2048] <surrogate-D800>..<surrogate-DFFF>
  		0xFEFF == code || // Cf       ZERO WIDTH NO-BREAK SPACE
  		(0xFFF0 <= code && code <= 0xFFF8) || // Cn   [9] <reserved-FFF0>..<reserved-FFF8>
  		(0xFFF9 <= code && code <= 0xFFFB) || // Cf   [3] INTERLINEAR ANNOTATION ANCHOR..INTERLINEAR ANNOTATION TERMINATOR
  		(0x1BCA0 <= code && code <= 0x1BCA3) || // Cf   [4] SHORTHAND FORMAT LETTER OVERLAP..SHORTHAND FORMAT UP STEP
  		(0x1D173 <= code && code <= 0x1D17A) || // Cf   [8] MUSICAL SYMBOL BEGIN BEAM..MUSICAL SYMBOL END PHRASE
  		0xE0000 == code || // Cn       <reserved-E0000>
  		0xE0001 == code || // Cf       LANGUAGE TAG
  		(0xE0002 <= code && code <= 0xE001F) || // Cn  [30] <reserved-E0002>..<reserved-E001F>
  		(0xE0080 <= code && code <= 0xE00FF) || // Cn [128] <reserved-E0080>..<reserved-E00FF>
  		(0xE01F0 <= code && code <= 0xE0FFF) // Cn [3600] <reserved-E01F0>..<reserved-E0FFF>
  		){
  			return Control;
  		}


  		if(
  		(0x0300 <= code && code <= 0x036F) || // Mn [112] COMBINING GRAVE ACCENT..COMBINING LATIN SMALL LETTER X
  		(0x0483 <= code && code <= 0x0487) || // Mn   [5] COMBINING CYRILLIC TITLO..COMBINING CYRILLIC POKRYTIE
  		(0x0488 <= code && code <= 0x0489) || // Me   [2] COMBINING CYRILLIC HUNDRED THOUSANDS SIGN..COMBINING CYRILLIC MILLIONS SIGN
  		(0x0591 <= code && code <= 0x05BD) || // Mn  [45] HEBREW ACCENT ETNAHTA..HEBREW POINT METEG
  		0x05BF == code || // Mn       HEBREW POINT RAFE
  		(0x05C1 <= code && code <= 0x05C2) || // Mn   [2] HEBREW POINT SHIN DOT..HEBREW POINT SIN DOT
  		(0x05C4 <= code && code <= 0x05C5) || // Mn   [2] HEBREW MARK UPPER DOT..HEBREW MARK LOWER DOT
  		0x05C7 == code || // Mn       HEBREW POINT QAMATS QATAN
  		(0x0610 <= code && code <= 0x061A) || // Mn  [11] ARABIC SIGN SALLALLAHOU ALAYHE WASSALLAM..ARABIC SMALL KASRA
  		(0x064B <= code && code <= 0x065F) || // Mn  [21] ARABIC FATHATAN..ARABIC WAVY HAMZA BELOW
  		0x0670 == code || // Mn       ARABIC LETTER SUPERSCRIPT ALEF
  		(0x06D6 <= code && code <= 0x06DC) || // Mn   [7] ARABIC SMALL HIGH LIGATURE SAD WITH LAM WITH ALEF MAKSURA..ARABIC SMALL HIGH SEEN
  		(0x06DF <= code && code <= 0x06E4) || // Mn   [6] ARABIC SMALL HIGH ROUNDED ZERO..ARABIC SMALL HIGH MADDA
  		(0x06E7 <= code && code <= 0x06E8) || // Mn   [2] ARABIC SMALL HIGH YEH..ARABIC SMALL HIGH NOON
  		(0x06EA <= code && code <= 0x06ED) || // Mn   [4] ARABIC EMPTY CENTRE LOW STOP..ARABIC SMALL LOW MEEM
  		0x0711 == code || // Mn       SYRIAC LETTER SUPERSCRIPT ALAPH
  		(0x0730 <= code && code <= 0x074A) || // Mn  [27] SYRIAC PTHAHA ABOVE..SYRIAC BARREKH
  		(0x07A6 <= code && code <= 0x07B0) || // Mn  [11] THAANA ABAFILI..THAANA SUKUN
  		(0x07EB <= code && code <= 0x07F3) || // Mn   [9] NKO COMBINING SHORT HIGH TONE..NKO COMBINING DOUBLE DOT ABOVE
  		(0x0816 <= code && code <= 0x0819) || // Mn   [4] SAMARITAN MARK IN..SAMARITAN MARK DAGESH
  		(0x081B <= code && code <= 0x0823) || // Mn   [9] SAMARITAN MARK EPENTHETIC YUT..SAMARITAN VOWEL SIGN A
  		(0x0825 <= code && code <= 0x0827) || // Mn   [3] SAMARITAN VOWEL SIGN SHORT A..SAMARITAN VOWEL SIGN U
  		(0x0829 <= code && code <= 0x082D) || // Mn   [5] SAMARITAN VOWEL SIGN LONG I..SAMARITAN MARK NEQUDAA
  		(0x0859 <= code && code <= 0x085B) || // Mn   [3] MANDAIC AFFRICATION MARK..MANDAIC GEMINATION MARK
  		(0x08D4 <= code && code <= 0x08E1) || // Mn  [14] ARABIC SMALL HIGH WORD AR-RUB..ARABIC SMALL HIGH SIGN SAFHA
  		(0x08E3 <= code && code <= 0x0902) || // Mn  [32] ARABIC TURNED DAMMA BELOW..DEVANAGARI SIGN ANUSVARA
  		0x093A == code || // Mn       DEVANAGARI VOWEL SIGN OE
  		0x093C == code || // Mn       DEVANAGARI SIGN NUKTA
  		(0x0941 <= code && code <= 0x0948) || // Mn   [8] DEVANAGARI VOWEL SIGN U..DEVANAGARI VOWEL SIGN AI
  		0x094D == code || // Mn       DEVANAGARI SIGN VIRAMA
  		(0x0951 <= code && code <= 0x0957) || // Mn   [7] DEVANAGARI STRESS SIGN UDATTA..DEVANAGARI VOWEL SIGN UUE
  		(0x0962 <= code && code <= 0x0963) || // Mn   [2] DEVANAGARI VOWEL SIGN VOCALIC L..DEVANAGARI VOWEL SIGN VOCALIC LL
  		0x0981 == code || // Mn       BENGALI SIGN CANDRABINDU
  		0x09BC == code || // Mn       BENGALI SIGN NUKTA
  		0x09BE == code || // Mc       BENGALI VOWEL SIGN AA
  		(0x09C1 <= code && code <= 0x09C4) || // Mn   [4] BENGALI VOWEL SIGN U..BENGALI VOWEL SIGN VOCALIC RR
  		0x09CD == code || // Mn       BENGALI SIGN VIRAMA
  		0x09D7 == code || // Mc       BENGALI AU LENGTH MARK
  		(0x09E2 <= code && code <= 0x09E3) || // Mn   [2] BENGALI VOWEL SIGN VOCALIC L..BENGALI VOWEL SIGN VOCALIC LL
  		(0x0A01 <= code && code <= 0x0A02) || // Mn   [2] GURMUKHI SIGN ADAK BINDI..GURMUKHI SIGN BINDI
  		0x0A3C == code || // Mn       GURMUKHI SIGN NUKTA
  		(0x0A41 <= code && code <= 0x0A42) || // Mn   [2] GURMUKHI VOWEL SIGN U..GURMUKHI VOWEL SIGN UU
  		(0x0A47 <= code && code <= 0x0A48) || // Mn   [2] GURMUKHI VOWEL SIGN EE..GURMUKHI VOWEL SIGN AI
  		(0x0A4B <= code && code <= 0x0A4D) || // Mn   [3] GURMUKHI VOWEL SIGN OO..GURMUKHI SIGN VIRAMA
  		0x0A51 == code || // Mn       GURMUKHI SIGN UDAAT
  		(0x0A70 <= code && code <= 0x0A71) || // Mn   [2] GURMUKHI TIPPI..GURMUKHI ADDAK
  		0x0A75 == code || // Mn       GURMUKHI SIGN YAKASH
  		(0x0A81 <= code && code <= 0x0A82) || // Mn   [2] GUJARATI SIGN CANDRABINDU..GUJARATI SIGN ANUSVARA
  		0x0ABC == code || // Mn       GUJARATI SIGN NUKTA
  		(0x0AC1 <= code && code <= 0x0AC5) || // Mn   [5] GUJARATI VOWEL SIGN U..GUJARATI VOWEL SIGN CANDRA E
  		(0x0AC7 <= code && code <= 0x0AC8) || // Mn   [2] GUJARATI VOWEL SIGN E..GUJARATI VOWEL SIGN AI
  		0x0ACD == code || // Mn       GUJARATI SIGN VIRAMA
  		(0x0AE2 <= code && code <= 0x0AE3) || // Mn   [2] GUJARATI VOWEL SIGN VOCALIC L..GUJARATI VOWEL SIGN VOCALIC LL
  		(0x0AFA <= code && code <= 0x0AFF) || // Mn   [6] GUJARATI SIGN SUKUN..GUJARATI SIGN TWO-CIRCLE NUKTA ABOVE
  		0x0B01 == code || // Mn       ORIYA SIGN CANDRABINDU
  		0x0B3C == code || // Mn       ORIYA SIGN NUKTA
  		0x0B3E == code || // Mc       ORIYA VOWEL SIGN AA
  		0x0B3F == code || // Mn       ORIYA VOWEL SIGN I
  		(0x0B41 <= code && code <= 0x0B44) || // Mn   [4] ORIYA VOWEL SIGN U..ORIYA VOWEL SIGN VOCALIC RR
  		0x0B4D == code || // Mn       ORIYA SIGN VIRAMA
  		0x0B56 == code || // Mn       ORIYA AI LENGTH MARK
  		0x0B57 == code || // Mc       ORIYA AU LENGTH MARK
  		(0x0B62 <= code && code <= 0x0B63) || // Mn   [2] ORIYA VOWEL SIGN VOCALIC L..ORIYA VOWEL SIGN VOCALIC LL
  		0x0B82 == code || // Mn       TAMIL SIGN ANUSVARA
  		0x0BBE == code || // Mc       TAMIL VOWEL SIGN AA
  		0x0BC0 == code || // Mn       TAMIL VOWEL SIGN II
  		0x0BCD == code || // Mn       TAMIL SIGN VIRAMA
  		0x0BD7 == code || // Mc       TAMIL AU LENGTH MARK
  		0x0C00 == code || // Mn       TELUGU SIGN COMBINING CANDRABINDU ABOVE
  		(0x0C3E <= code && code <= 0x0C40) || // Mn   [3] TELUGU VOWEL SIGN AA..TELUGU VOWEL SIGN II
  		(0x0C46 <= code && code <= 0x0C48) || // Mn   [3] TELUGU VOWEL SIGN E..TELUGU VOWEL SIGN AI
  		(0x0C4A <= code && code <= 0x0C4D) || // Mn   [4] TELUGU VOWEL SIGN O..TELUGU SIGN VIRAMA
  		(0x0C55 <= code && code <= 0x0C56) || // Mn   [2] TELUGU LENGTH MARK..TELUGU AI LENGTH MARK
  		(0x0C62 <= code && code <= 0x0C63) || // Mn   [2] TELUGU VOWEL SIGN VOCALIC L..TELUGU VOWEL SIGN VOCALIC LL
  		0x0C81 == code || // Mn       KANNADA SIGN CANDRABINDU
  		0x0CBC == code || // Mn       KANNADA SIGN NUKTA
  		0x0CBF == code || // Mn       KANNADA VOWEL SIGN I
  		0x0CC2 == code || // Mc       KANNADA VOWEL SIGN UU
  		0x0CC6 == code || // Mn       KANNADA VOWEL SIGN E
  		(0x0CCC <= code && code <= 0x0CCD) || // Mn   [2] KANNADA VOWEL SIGN AU..KANNADA SIGN VIRAMA
  		(0x0CD5 <= code && code <= 0x0CD6) || // Mc   [2] KANNADA LENGTH MARK..KANNADA AI LENGTH MARK
  		(0x0CE2 <= code && code <= 0x0CE3) || // Mn   [2] KANNADA VOWEL SIGN VOCALIC L..KANNADA VOWEL SIGN VOCALIC LL
  		(0x0D00 <= code && code <= 0x0D01) || // Mn   [2] MALAYALAM SIGN COMBINING ANUSVARA ABOVE..MALAYALAM SIGN CANDRABINDU
  		(0x0D3B <= code && code <= 0x0D3C) || // Mn   [2] MALAYALAM SIGN VERTICAL BAR VIRAMA..MALAYALAM SIGN CIRCULAR VIRAMA
  		0x0D3E == code || // Mc       MALAYALAM VOWEL SIGN AA
  		(0x0D41 <= code && code <= 0x0D44) || // Mn   [4] MALAYALAM VOWEL SIGN U..MALAYALAM VOWEL SIGN VOCALIC RR
  		0x0D4D == code || // Mn       MALAYALAM SIGN VIRAMA
  		0x0D57 == code || // Mc       MALAYALAM AU LENGTH MARK
  		(0x0D62 <= code && code <= 0x0D63) || // Mn   [2] MALAYALAM VOWEL SIGN VOCALIC L..MALAYALAM VOWEL SIGN VOCALIC LL
  		0x0DCA == code || // Mn       SINHALA SIGN AL-LAKUNA
  		0x0DCF == code || // Mc       SINHALA VOWEL SIGN AELA-PILLA
  		(0x0DD2 <= code && code <= 0x0DD4) || // Mn   [3] SINHALA VOWEL SIGN KETTI IS-PILLA..SINHALA VOWEL SIGN KETTI PAA-PILLA
  		0x0DD6 == code || // Mn       SINHALA VOWEL SIGN DIGA PAA-PILLA
  		0x0DDF == code || // Mc       SINHALA VOWEL SIGN GAYANUKITTA
  		0x0E31 == code || // Mn       THAI CHARACTER MAI HAN-AKAT
  		(0x0E34 <= code && code <= 0x0E3A) || // Mn   [7] THAI CHARACTER SARA I..THAI CHARACTER PHINTHU
  		(0x0E47 <= code && code <= 0x0E4E) || // Mn   [8] THAI CHARACTER MAITAIKHU..THAI CHARACTER YAMAKKAN
  		0x0EB1 == code || // Mn       LAO VOWEL SIGN MAI KAN
  		(0x0EB4 <= code && code <= 0x0EB9) || // Mn   [6] LAO VOWEL SIGN I..LAO VOWEL SIGN UU
  		(0x0EBB <= code && code <= 0x0EBC) || // Mn   [2] LAO VOWEL SIGN MAI KON..LAO SEMIVOWEL SIGN LO
  		(0x0EC8 <= code && code <= 0x0ECD) || // Mn   [6] LAO TONE MAI EK..LAO NIGGAHITA
  		(0x0F18 <= code && code <= 0x0F19) || // Mn   [2] TIBETAN ASTROLOGICAL SIGN -KHYUD PA..TIBETAN ASTROLOGICAL SIGN SDONG TSHUGS
  		0x0F35 == code || // Mn       TIBETAN MARK NGAS BZUNG NYI ZLA
  		0x0F37 == code || // Mn       TIBETAN MARK NGAS BZUNG SGOR RTAGS
  		0x0F39 == code || // Mn       TIBETAN MARK TSA -PHRU
  		(0x0F71 <= code && code <= 0x0F7E) || // Mn  [14] TIBETAN VOWEL SIGN AA..TIBETAN SIGN RJES SU NGA RO
  		(0x0F80 <= code && code <= 0x0F84) || // Mn   [5] TIBETAN VOWEL SIGN REVERSED I..TIBETAN MARK HALANTA
  		(0x0F86 <= code && code <= 0x0F87) || // Mn   [2] TIBETAN SIGN LCI RTAGS..TIBETAN SIGN YANG RTAGS
  		(0x0F8D <= code && code <= 0x0F97) || // Mn  [11] TIBETAN SUBJOINED SIGN LCE TSA CAN..TIBETAN SUBJOINED LETTER JA
  		(0x0F99 <= code && code <= 0x0FBC) || // Mn  [36] TIBETAN SUBJOINED LETTER NYA..TIBETAN SUBJOINED LETTER FIXED-FORM RA
  		0x0FC6 == code || // Mn       TIBETAN SYMBOL PADMA GDAN
  		(0x102D <= code && code <= 0x1030) || // Mn   [4] MYANMAR VOWEL SIGN I..MYANMAR VOWEL SIGN UU
  		(0x1032 <= code && code <= 0x1037) || // Mn   [6] MYANMAR VOWEL SIGN AI..MYANMAR SIGN DOT BELOW
  		(0x1039 <= code && code <= 0x103A) || // Mn   [2] MYANMAR SIGN VIRAMA..MYANMAR SIGN ASAT
  		(0x103D <= code && code <= 0x103E) || // Mn   [2] MYANMAR CONSONANT SIGN MEDIAL WA..MYANMAR CONSONANT SIGN MEDIAL HA
  		(0x1058 <= code && code <= 0x1059) || // Mn   [2] MYANMAR VOWEL SIGN VOCALIC L..MYANMAR VOWEL SIGN VOCALIC LL
  		(0x105E <= code && code <= 0x1060) || // Mn   [3] MYANMAR CONSONANT SIGN MON MEDIAL NA..MYANMAR CONSONANT SIGN MON MEDIAL LA
  		(0x1071 <= code && code <= 0x1074) || // Mn   [4] MYANMAR VOWEL SIGN GEBA KAREN I..MYANMAR VOWEL SIGN KAYAH EE
  		0x1082 == code || // Mn       MYANMAR CONSONANT SIGN SHAN MEDIAL WA
  		(0x1085 <= code && code <= 0x1086) || // Mn   [2] MYANMAR VOWEL SIGN SHAN E ABOVE..MYANMAR VOWEL SIGN SHAN FINAL Y
  		0x108D == code || // Mn       MYANMAR SIGN SHAN COUNCIL EMPHATIC TONE
  		0x109D == code || // Mn       MYANMAR VOWEL SIGN AITON AI
  		(0x135D <= code && code <= 0x135F) || // Mn   [3] ETHIOPIC COMBINING GEMINATION AND VOWEL LENGTH MARK..ETHIOPIC COMBINING GEMINATION MARK
  		(0x1712 <= code && code <= 0x1714) || // Mn   [3] TAGALOG VOWEL SIGN I..TAGALOG SIGN VIRAMA
  		(0x1732 <= code && code <= 0x1734) || // Mn   [3] HANUNOO VOWEL SIGN I..HANUNOO SIGN PAMUDPOD
  		(0x1752 <= code && code <= 0x1753) || // Mn   [2] BUHID VOWEL SIGN I..BUHID VOWEL SIGN U
  		(0x1772 <= code && code <= 0x1773) || // Mn   [2] TAGBANWA VOWEL SIGN I..TAGBANWA VOWEL SIGN U
  		(0x17B4 <= code && code <= 0x17B5) || // Mn   [2] KHMER VOWEL INHERENT AQ..KHMER VOWEL INHERENT AA
  		(0x17B7 <= code && code <= 0x17BD) || // Mn   [7] KHMER VOWEL SIGN I..KHMER VOWEL SIGN UA
  		0x17C6 == code || // Mn       KHMER SIGN NIKAHIT
  		(0x17C9 <= code && code <= 0x17D3) || // Mn  [11] KHMER SIGN MUUSIKATOAN..KHMER SIGN BATHAMASAT
  		0x17DD == code || // Mn       KHMER SIGN ATTHACAN
  		(0x180B <= code && code <= 0x180D) || // Mn   [3] MONGOLIAN FREE VARIATION SELECTOR ONE..MONGOLIAN FREE VARIATION SELECTOR THREE
  		(0x1885 <= code && code <= 0x1886) || // Mn   [2] MONGOLIAN LETTER ALI GALI BALUDA..MONGOLIAN LETTER ALI GALI THREE BALUDA
  		0x18A9 == code || // Mn       MONGOLIAN LETTER ALI GALI DAGALGA
  		(0x1920 <= code && code <= 0x1922) || // Mn   [3] LIMBU VOWEL SIGN A..LIMBU VOWEL SIGN U
  		(0x1927 <= code && code <= 0x1928) || // Mn   [2] LIMBU VOWEL SIGN E..LIMBU VOWEL SIGN O
  		0x1932 == code || // Mn       LIMBU SMALL LETTER ANUSVARA
  		(0x1939 <= code && code <= 0x193B) || // Mn   [3] LIMBU SIGN MUKPHRENG..LIMBU SIGN SA-I
  		(0x1A17 <= code && code <= 0x1A18) || // Mn   [2] BUGINESE VOWEL SIGN I..BUGINESE VOWEL SIGN U
  		0x1A1B == code || // Mn       BUGINESE VOWEL SIGN AE
  		0x1A56 == code || // Mn       TAI THAM CONSONANT SIGN MEDIAL LA
  		(0x1A58 <= code && code <= 0x1A5E) || // Mn   [7] TAI THAM SIGN MAI KANG LAI..TAI THAM CONSONANT SIGN SA
  		0x1A60 == code || // Mn       TAI THAM SIGN SAKOT
  		0x1A62 == code || // Mn       TAI THAM VOWEL SIGN MAI SAT
  		(0x1A65 <= code && code <= 0x1A6C) || // Mn   [8] TAI THAM VOWEL SIGN I..TAI THAM VOWEL SIGN OA BELOW
  		(0x1A73 <= code && code <= 0x1A7C) || // Mn  [10] TAI THAM VOWEL SIGN OA ABOVE..TAI THAM SIGN KHUEN-LUE KARAN
  		0x1A7F == code || // Mn       TAI THAM COMBINING CRYPTOGRAMMIC DOT
  		(0x1AB0 <= code && code <= 0x1ABD) || // Mn  [14] COMBINING DOUBLED CIRCUMFLEX ACCENT..COMBINING PARENTHESES BELOW
  		0x1ABE == code || // Me       COMBINING PARENTHESES OVERLAY
  		(0x1B00 <= code && code <= 0x1B03) || // Mn   [4] BALINESE SIGN ULU RICEM..BALINESE SIGN SURANG
  		0x1B34 == code || // Mn       BALINESE SIGN REREKAN
  		(0x1B36 <= code && code <= 0x1B3A) || // Mn   [5] BALINESE VOWEL SIGN ULU..BALINESE VOWEL SIGN RA REPA
  		0x1B3C == code || // Mn       BALINESE VOWEL SIGN LA LENGA
  		0x1B42 == code || // Mn       BALINESE VOWEL SIGN PEPET
  		(0x1B6B <= code && code <= 0x1B73) || // Mn   [9] BALINESE MUSICAL SYMBOL COMBINING TEGEH..BALINESE MUSICAL SYMBOL COMBINING GONG
  		(0x1B80 <= code && code <= 0x1B81) || // Mn   [2] SUNDANESE SIGN PANYECEK..SUNDANESE SIGN PANGLAYAR
  		(0x1BA2 <= code && code <= 0x1BA5) || // Mn   [4] SUNDANESE CONSONANT SIGN PANYAKRA..SUNDANESE VOWEL SIGN PANYUKU
  		(0x1BA8 <= code && code <= 0x1BA9) || // Mn   [2] SUNDANESE VOWEL SIGN PAMEPET..SUNDANESE VOWEL SIGN PANEULEUNG
  		(0x1BAB <= code && code <= 0x1BAD) || // Mn   [3] SUNDANESE SIGN VIRAMA..SUNDANESE CONSONANT SIGN PASANGAN WA
  		0x1BE6 == code || // Mn       BATAK SIGN TOMPI
  		(0x1BE8 <= code && code <= 0x1BE9) || // Mn   [2] BATAK VOWEL SIGN PAKPAK E..BATAK VOWEL SIGN EE
  		0x1BED == code || // Mn       BATAK VOWEL SIGN KARO O
  		(0x1BEF <= code && code <= 0x1BF1) || // Mn   [3] BATAK VOWEL SIGN U FOR SIMALUNGUN SA..BATAK CONSONANT SIGN H
  		(0x1C2C <= code && code <= 0x1C33) || // Mn   [8] LEPCHA VOWEL SIGN E..LEPCHA CONSONANT SIGN T
  		(0x1C36 <= code && code <= 0x1C37) || // Mn   [2] LEPCHA SIGN RAN..LEPCHA SIGN NUKTA
  		(0x1CD0 <= code && code <= 0x1CD2) || // Mn   [3] VEDIC TONE KARSHANA..VEDIC TONE PRENKHA
  		(0x1CD4 <= code && code <= 0x1CE0) || // Mn  [13] VEDIC SIGN YAJURVEDIC MIDLINE SVARITA..VEDIC TONE RIGVEDIC KASHMIRI INDEPENDENT SVARITA
  		(0x1CE2 <= code && code <= 0x1CE8) || // Mn   [7] VEDIC SIGN VISARGA SVARITA..VEDIC SIGN VISARGA ANUDATTA WITH TAIL
  		0x1CED == code || // Mn       VEDIC SIGN TIRYAK
  		0x1CF4 == code || // Mn       VEDIC TONE CANDRA ABOVE
  		(0x1CF8 <= code && code <= 0x1CF9) || // Mn   [2] VEDIC TONE RING ABOVE..VEDIC TONE DOUBLE RING ABOVE
  		(0x1DC0 <= code && code <= 0x1DF9) || // Mn  [58] COMBINING DOTTED GRAVE ACCENT..COMBINING WIDE INVERTED BRIDGE BELOW
  		(0x1DFB <= code && code <= 0x1DFF) || // Mn   [5] COMBINING DELETION MARK..COMBINING RIGHT ARROWHEAD AND DOWN ARROWHEAD BELOW
  		0x200C == code || // Cf       ZERO WIDTH NON-JOINER
  		(0x20D0 <= code && code <= 0x20DC) || // Mn  [13] COMBINING LEFT HARPOON ABOVE..COMBINING FOUR DOTS ABOVE
  		(0x20DD <= code && code <= 0x20E0) || // Me   [4] COMBINING ENCLOSING CIRCLE..COMBINING ENCLOSING CIRCLE BACKSLASH
  		0x20E1 == code || // Mn       COMBINING LEFT RIGHT ARROW ABOVE
  		(0x20E2 <= code && code <= 0x20E4) || // Me   [3] COMBINING ENCLOSING SCREEN..COMBINING ENCLOSING UPWARD POINTING TRIANGLE
  		(0x20E5 <= code && code <= 0x20F0) || // Mn  [12] COMBINING REVERSE SOLIDUS OVERLAY..COMBINING ASTERISK ABOVE
  		(0x2CEF <= code && code <= 0x2CF1) || // Mn   [3] COPTIC COMBINING NI ABOVE..COPTIC COMBINING SPIRITUS LENIS
  		0x2D7F == code || // Mn       TIFINAGH CONSONANT JOINER
  		(0x2DE0 <= code && code <= 0x2DFF) || // Mn  [32] COMBINING CYRILLIC LETTER BE..COMBINING CYRILLIC LETTER IOTIFIED BIG YUS
  		(0x302A <= code && code <= 0x302D) || // Mn   [4] IDEOGRAPHIC LEVEL TONE MARK..IDEOGRAPHIC ENTERING TONE MARK
  		(0x302E <= code && code <= 0x302F) || // Mc   [2] HANGUL SINGLE DOT TONE MARK..HANGUL DOUBLE DOT TONE MARK
  		(0x3099 <= code && code <= 0x309A) || // Mn   [2] COMBINING KATAKANA-HIRAGANA VOICED SOUND MARK..COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK
  		0xA66F == code || // Mn       COMBINING CYRILLIC VZMET
  		(0xA670 <= code && code <= 0xA672) || // Me   [3] COMBINING CYRILLIC TEN MILLIONS SIGN..COMBINING CYRILLIC THOUSAND MILLIONS SIGN
  		(0xA674 <= code && code <= 0xA67D) || // Mn  [10] COMBINING CYRILLIC LETTER UKRAINIAN IE..COMBINING CYRILLIC PAYEROK
  		(0xA69E <= code && code <= 0xA69F) || // Mn   [2] COMBINING CYRILLIC LETTER EF..COMBINING CYRILLIC LETTER IOTIFIED E
  		(0xA6F0 <= code && code <= 0xA6F1) || // Mn   [2] BAMUM COMBINING MARK KOQNDON..BAMUM COMBINING MARK TUKWENTIS
  		0xA802 == code || // Mn       SYLOTI NAGRI SIGN DVISVARA
  		0xA806 == code || // Mn       SYLOTI NAGRI SIGN HASANTA
  		0xA80B == code || // Mn       SYLOTI NAGRI SIGN ANUSVARA
  		(0xA825 <= code && code <= 0xA826) || // Mn   [2] SYLOTI NAGRI VOWEL SIGN U..SYLOTI NAGRI VOWEL SIGN E
  		(0xA8C4 <= code && code <= 0xA8C5) || // Mn   [2] SAURASHTRA SIGN VIRAMA..SAURASHTRA SIGN CANDRABINDU
  		(0xA8E0 <= code && code <= 0xA8F1) || // Mn  [18] COMBINING DEVANAGARI DIGIT ZERO..COMBINING DEVANAGARI SIGN AVAGRAHA
  		(0xA926 <= code && code <= 0xA92D) || // Mn   [8] KAYAH LI VOWEL UE..KAYAH LI TONE CALYA PLOPHU
  		(0xA947 <= code && code <= 0xA951) || // Mn  [11] REJANG VOWEL SIGN I..REJANG CONSONANT SIGN R
  		(0xA980 <= code && code <= 0xA982) || // Mn   [3] JAVANESE SIGN PANYANGGA..JAVANESE SIGN LAYAR
  		0xA9B3 == code || // Mn       JAVANESE SIGN CECAK TELU
  		(0xA9B6 <= code && code <= 0xA9B9) || // Mn   [4] JAVANESE VOWEL SIGN WULU..JAVANESE VOWEL SIGN SUKU MENDUT
  		0xA9BC == code || // Mn       JAVANESE VOWEL SIGN PEPET
  		0xA9E5 == code || // Mn       MYANMAR SIGN SHAN SAW
  		(0xAA29 <= code && code <= 0xAA2E) || // Mn   [6] CHAM VOWEL SIGN AA..CHAM VOWEL SIGN OE
  		(0xAA31 <= code && code <= 0xAA32) || // Mn   [2] CHAM VOWEL SIGN AU..CHAM VOWEL SIGN UE
  		(0xAA35 <= code && code <= 0xAA36) || // Mn   [2] CHAM CONSONANT SIGN LA..CHAM CONSONANT SIGN WA
  		0xAA43 == code || // Mn       CHAM CONSONANT SIGN FINAL NG
  		0xAA4C == code || // Mn       CHAM CONSONANT SIGN FINAL M
  		0xAA7C == code || // Mn       MYANMAR SIGN TAI LAING TONE-2
  		0xAAB0 == code || // Mn       TAI VIET MAI KANG
  		(0xAAB2 <= code && code <= 0xAAB4) || // Mn   [3] TAI VIET VOWEL I..TAI VIET VOWEL U
  		(0xAAB7 <= code && code <= 0xAAB8) || // Mn   [2] TAI VIET MAI KHIT..TAI VIET VOWEL IA
  		(0xAABE <= code && code <= 0xAABF) || // Mn   [2] TAI VIET VOWEL AM..TAI VIET TONE MAI EK
  		0xAAC1 == code || // Mn       TAI VIET TONE MAI THO
  		(0xAAEC <= code && code <= 0xAAED) || // Mn   [2] MEETEI MAYEK VOWEL SIGN UU..MEETEI MAYEK VOWEL SIGN AAI
  		0xAAF6 == code || // Mn       MEETEI MAYEK VIRAMA
  		0xABE5 == code || // Mn       MEETEI MAYEK VOWEL SIGN ANAP
  		0xABE8 == code || // Mn       MEETEI MAYEK VOWEL SIGN UNAP
  		0xABED == code || // Mn       MEETEI MAYEK APUN IYEK
  		0xFB1E == code || // Mn       HEBREW POINT JUDEO-SPANISH VARIKA
  		(0xFE00 <= code && code <= 0xFE0F) || // Mn  [16] VARIATION SELECTOR-1..VARIATION SELECTOR-16
  		(0xFE20 <= code && code <= 0xFE2F) || // Mn  [16] COMBINING LIGATURE LEFT HALF..COMBINING CYRILLIC TITLO RIGHT HALF
  		(0xFF9E <= code && code <= 0xFF9F) || // Lm   [2] HALFWIDTH KATAKANA VOICED SOUND MARK..HALFWIDTH KATAKANA SEMI-VOICED SOUND MARK
  		0x101FD == code || // Mn       PHAISTOS DISC SIGN COMBINING OBLIQUE STROKE
  		0x102E0 == code || // Mn       COPTIC EPACT THOUSANDS MARK
  		(0x10376 <= code && code <= 0x1037A) || // Mn   [5] COMBINING OLD PERMIC LETTER AN..COMBINING OLD PERMIC LETTER SII
  		(0x10A01 <= code && code <= 0x10A03) || // Mn   [3] KHAROSHTHI VOWEL SIGN I..KHAROSHTHI VOWEL SIGN VOCALIC R
  		(0x10A05 <= code && code <= 0x10A06) || // Mn   [2] KHAROSHTHI VOWEL SIGN E..KHAROSHTHI VOWEL SIGN O
  		(0x10A0C <= code && code <= 0x10A0F) || // Mn   [4] KHAROSHTHI VOWEL LENGTH MARK..KHAROSHTHI SIGN VISARGA
  		(0x10A38 <= code && code <= 0x10A3A) || // Mn   [3] KHAROSHTHI SIGN BAR ABOVE..KHAROSHTHI SIGN DOT BELOW
  		0x10A3F == code || // Mn       KHAROSHTHI VIRAMA
  		(0x10AE5 <= code && code <= 0x10AE6) || // Mn   [2] MANICHAEAN ABBREVIATION MARK ABOVE..MANICHAEAN ABBREVIATION MARK BELOW
  		0x11001 == code || // Mn       BRAHMI SIGN ANUSVARA
  		(0x11038 <= code && code <= 0x11046) || // Mn  [15] BRAHMI VOWEL SIGN AA..BRAHMI VIRAMA
  		(0x1107F <= code && code <= 0x11081) || // Mn   [3] BRAHMI NUMBER JOINER..KAITHI SIGN ANUSVARA
  		(0x110B3 <= code && code <= 0x110B6) || // Mn   [4] KAITHI VOWEL SIGN U..KAITHI VOWEL SIGN AI
  		(0x110B9 <= code && code <= 0x110BA) || // Mn   [2] KAITHI SIGN VIRAMA..KAITHI SIGN NUKTA
  		(0x11100 <= code && code <= 0x11102) || // Mn   [3] CHAKMA SIGN CANDRABINDU..CHAKMA SIGN VISARGA
  		(0x11127 <= code && code <= 0x1112B) || // Mn   [5] CHAKMA VOWEL SIGN A..CHAKMA VOWEL SIGN UU
  		(0x1112D <= code && code <= 0x11134) || // Mn   [8] CHAKMA VOWEL SIGN AI..CHAKMA MAAYYAA
  		0x11173 == code || // Mn       MAHAJANI SIGN NUKTA
  		(0x11180 <= code && code <= 0x11181) || // Mn   [2] SHARADA SIGN CANDRABINDU..SHARADA SIGN ANUSVARA
  		(0x111B6 <= code && code <= 0x111BE) || // Mn   [9] SHARADA VOWEL SIGN U..SHARADA VOWEL SIGN O
  		(0x111CA <= code && code <= 0x111CC) || // Mn   [3] SHARADA SIGN NUKTA..SHARADA EXTRA SHORT VOWEL MARK
  		(0x1122F <= code && code <= 0x11231) || // Mn   [3] KHOJKI VOWEL SIGN U..KHOJKI VOWEL SIGN AI
  		0x11234 == code || // Mn       KHOJKI SIGN ANUSVARA
  		(0x11236 <= code && code <= 0x11237) || // Mn   [2] KHOJKI SIGN NUKTA..KHOJKI SIGN SHADDA
  		0x1123E == code || // Mn       KHOJKI SIGN SUKUN
  		0x112DF == code || // Mn       KHUDAWADI SIGN ANUSVARA
  		(0x112E3 <= code && code <= 0x112EA) || // Mn   [8] KHUDAWADI VOWEL SIGN U..KHUDAWADI SIGN VIRAMA
  		(0x11300 <= code && code <= 0x11301) || // Mn   [2] GRANTHA SIGN COMBINING ANUSVARA ABOVE..GRANTHA SIGN CANDRABINDU
  		0x1133C == code || // Mn       GRANTHA SIGN NUKTA
  		0x1133E == code || // Mc       GRANTHA VOWEL SIGN AA
  		0x11340 == code || // Mn       GRANTHA VOWEL SIGN II
  		0x11357 == code || // Mc       GRANTHA AU LENGTH MARK
  		(0x11366 <= code && code <= 0x1136C) || // Mn   [7] COMBINING GRANTHA DIGIT ZERO..COMBINING GRANTHA DIGIT SIX
  		(0x11370 <= code && code <= 0x11374) || // Mn   [5] COMBINING GRANTHA LETTER A..COMBINING GRANTHA LETTER PA
  		(0x11438 <= code && code <= 0x1143F) || // Mn   [8] NEWA VOWEL SIGN U..NEWA VOWEL SIGN AI
  		(0x11442 <= code && code <= 0x11444) || // Mn   [3] NEWA SIGN VIRAMA..NEWA SIGN ANUSVARA
  		0x11446 == code || // Mn       NEWA SIGN NUKTA
  		0x114B0 == code || // Mc       TIRHUTA VOWEL SIGN AA
  		(0x114B3 <= code && code <= 0x114B8) || // Mn   [6] TIRHUTA VOWEL SIGN U..TIRHUTA VOWEL SIGN VOCALIC LL
  		0x114BA == code || // Mn       TIRHUTA VOWEL SIGN SHORT E
  		0x114BD == code || // Mc       TIRHUTA VOWEL SIGN SHORT O
  		(0x114BF <= code && code <= 0x114C0) || // Mn   [2] TIRHUTA SIGN CANDRABINDU..TIRHUTA SIGN ANUSVARA
  		(0x114C2 <= code && code <= 0x114C3) || // Mn   [2] TIRHUTA SIGN VIRAMA..TIRHUTA SIGN NUKTA
  		0x115AF == code || // Mc       SIDDHAM VOWEL SIGN AA
  		(0x115B2 <= code && code <= 0x115B5) || // Mn   [4] SIDDHAM VOWEL SIGN U..SIDDHAM VOWEL SIGN VOCALIC RR
  		(0x115BC <= code && code <= 0x115BD) || // Mn   [2] SIDDHAM SIGN CANDRABINDU..SIDDHAM SIGN ANUSVARA
  		(0x115BF <= code && code <= 0x115C0) || // Mn   [2] SIDDHAM SIGN VIRAMA..SIDDHAM SIGN NUKTA
  		(0x115DC <= code && code <= 0x115DD) || // Mn   [2] SIDDHAM VOWEL SIGN ALTERNATE U..SIDDHAM VOWEL SIGN ALTERNATE UU
  		(0x11633 <= code && code <= 0x1163A) || // Mn   [8] MODI VOWEL SIGN U..MODI VOWEL SIGN AI
  		0x1163D == code || // Mn       MODI SIGN ANUSVARA
  		(0x1163F <= code && code <= 0x11640) || // Mn   [2] MODI SIGN VIRAMA..MODI SIGN ARDHACANDRA
  		0x116AB == code || // Mn       TAKRI SIGN ANUSVARA
  		0x116AD == code || // Mn       TAKRI VOWEL SIGN AA
  		(0x116B0 <= code && code <= 0x116B5) || // Mn   [6] TAKRI VOWEL SIGN U..TAKRI VOWEL SIGN AU
  		0x116B7 == code || // Mn       TAKRI SIGN NUKTA
  		(0x1171D <= code && code <= 0x1171F) || // Mn   [3] AHOM CONSONANT SIGN MEDIAL LA..AHOM CONSONANT SIGN MEDIAL LIGATING RA
  		(0x11722 <= code && code <= 0x11725) || // Mn   [4] AHOM VOWEL SIGN I..AHOM VOWEL SIGN UU
  		(0x11727 <= code && code <= 0x1172B) || // Mn   [5] AHOM VOWEL SIGN AW..AHOM SIGN KILLER
  		(0x11A01 <= code && code <= 0x11A06) || // Mn   [6] ZANABAZAR SQUARE VOWEL SIGN I..ZANABAZAR SQUARE VOWEL SIGN O
  		(0x11A09 <= code && code <= 0x11A0A) || // Mn   [2] ZANABAZAR SQUARE VOWEL SIGN REVERSED I..ZANABAZAR SQUARE VOWEL LENGTH MARK
  		(0x11A33 <= code && code <= 0x11A38) || // Mn   [6] ZANABAZAR SQUARE FINAL CONSONANT MARK..ZANABAZAR SQUARE SIGN ANUSVARA
  		(0x11A3B <= code && code <= 0x11A3E) || // Mn   [4] ZANABAZAR SQUARE CLUSTER-FINAL LETTER YA..ZANABAZAR SQUARE CLUSTER-FINAL LETTER VA
  		0x11A47 == code || // Mn       ZANABAZAR SQUARE SUBJOINER
  		(0x11A51 <= code && code <= 0x11A56) || // Mn   [6] SOYOMBO VOWEL SIGN I..SOYOMBO VOWEL SIGN OE
  		(0x11A59 <= code && code <= 0x11A5B) || // Mn   [3] SOYOMBO VOWEL SIGN VOCALIC R..SOYOMBO VOWEL LENGTH MARK
  		(0x11A8A <= code && code <= 0x11A96) || // Mn  [13] SOYOMBO FINAL CONSONANT SIGN G..SOYOMBO SIGN ANUSVARA
  		(0x11A98 <= code && code <= 0x11A99) || // Mn   [2] SOYOMBO GEMINATION MARK..SOYOMBO SUBJOINER
  		(0x11C30 <= code && code <= 0x11C36) || // Mn   [7] BHAIKSUKI VOWEL SIGN I..BHAIKSUKI VOWEL SIGN VOCALIC L
  		(0x11C38 <= code && code <= 0x11C3D) || // Mn   [6] BHAIKSUKI VOWEL SIGN E..BHAIKSUKI SIGN ANUSVARA
  		0x11C3F == code || // Mn       BHAIKSUKI SIGN VIRAMA
  		(0x11C92 <= code && code <= 0x11CA7) || // Mn  [22] MARCHEN SUBJOINED LETTER KA..MARCHEN SUBJOINED LETTER ZA
  		(0x11CAA <= code && code <= 0x11CB0) || // Mn   [7] MARCHEN SUBJOINED LETTER RA..MARCHEN VOWEL SIGN AA
  		(0x11CB2 <= code && code <= 0x11CB3) || // Mn   [2] MARCHEN VOWEL SIGN U..MARCHEN VOWEL SIGN E
  		(0x11CB5 <= code && code <= 0x11CB6) || // Mn   [2] MARCHEN SIGN ANUSVARA..MARCHEN SIGN CANDRABINDU
  		(0x11D31 <= code && code <= 0x11D36) || // Mn   [6] MASARAM GONDI VOWEL SIGN AA..MASARAM GONDI VOWEL SIGN VOCALIC R
  		0x11D3A == code || // Mn       MASARAM GONDI VOWEL SIGN E
  		(0x11D3C <= code && code <= 0x11D3D) || // Mn   [2] MASARAM GONDI VOWEL SIGN AI..MASARAM GONDI VOWEL SIGN O
  		(0x11D3F <= code && code <= 0x11D45) || // Mn   [7] MASARAM GONDI VOWEL SIGN AU..MASARAM GONDI VIRAMA
  		0x11D47 == code || // Mn       MASARAM GONDI RA-KARA
  		(0x16AF0 <= code && code <= 0x16AF4) || // Mn   [5] BASSA VAH COMBINING HIGH TONE..BASSA VAH COMBINING HIGH-LOW TONE
  		(0x16B30 <= code && code <= 0x16B36) || // Mn   [7] PAHAWH HMONG MARK CIM TUB..PAHAWH HMONG MARK CIM TAUM
  		(0x16F8F <= code && code <= 0x16F92) || // Mn   [4] MIAO TONE RIGHT..MIAO TONE BELOW
  		(0x1BC9D <= code && code <= 0x1BC9E) || // Mn   [2] DUPLOYAN THICK LETTER SELECTOR..DUPLOYAN DOUBLE MARK
  		0x1D165 == code || // Mc       MUSICAL SYMBOL COMBINING STEM
  		(0x1D167 <= code && code <= 0x1D169) || // Mn   [3] MUSICAL SYMBOL COMBINING TREMOLO-1..MUSICAL SYMBOL COMBINING TREMOLO-3
  		(0x1D16E <= code && code <= 0x1D172) || // Mc   [5] MUSICAL SYMBOL COMBINING FLAG-1..MUSICAL SYMBOL COMBINING FLAG-5
  		(0x1D17B <= code && code <= 0x1D182) || // Mn   [8] MUSICAL SYMBOL COMBINING ACCENT..MUSICAL SYMBOL COMBINING LOURE
  		(0x1D185 <= code && code <= 0x1D18B) || // Mn   [7] MUSICAL SYMBOL COMBINING DOIT..MUSICAL SYMBOL COMBINING TRIPLE TONGUE
  		(0x1D1AA <= code && code <= 0x1D1AD) || // Mn   [4] MUSICAL SYMBOL COMBINING DOWN BOW..MUSICAL SYMBOL COMBINING SNAP PIZZICATO
  		(0x1D242 <= code && code <= 0x1D244) || // Mn   [3] COMBINING GREEK MUSICAL TRISEME..COMBINING GREEK MUSICAL PENTASEME
  		(0x1DA00 <= code && code <= 0x1DA36) || // Mn  [55] SIGNWRITING HEAD RIM..SIGNWRITING AIR SUCKING IN
  		(0x1DA3B <= code && code <= 0x1DA6C) || // Mn  [50] SIGNWRITING MOUTH CLOSED NEUTRAL..SIGNWRITING EXCITEMENT
  		0x1DA75 == code || // Mn       SIGNWRITING UPPER BODY TILTING FROM HIP JOINTS
  		0x1DA84 == code || // Mn       SIGNWRITING LOCATION HEAD NECK
  		(0x1DA9B <= code && code <= 0x1DA9F) || // Mn   [5] SIGNWRITING FILL MODIFIER-2..SIGNWRITING FILL MODIFIER-6
  		(0x1DAA1 <= code && code <= 0x1DAAF) || // Mn  [15] SIGNWRITING ROTATION MODIFIER-2..SIGNWRITING ROTATION MODIFIER-16
  		(0x1E000 <= code && code <= 0x1E006) || // Mn   [7] COMBINING GLAGOLITIC LETTER AZU..COMBINING GLAGOLITIC LETTER ZHIVETE
  		(0x1E008 <= code && code <= 0x1E018) || // Mn  [17] COMBINING GLAGOLITIC LETTER ZEMLJA..COMBINING GLAGOLITIC LETTER HERU
  		(0x1E01B <= code && code <= 0x1E021) || // Mn   [7] COMBINING GLAGOLITIC LETTER SHTA..COMBINING GLAGOLITIC LETTER YATI
  		(0x1E023 <= code && code <= 0x1E024) || // Mn   [2] COMBINING GLAGOLITIC LETTER YU..COMBINING GLAGOLITIC LETTER SMALL YUS
  		(0x1E026 <= code && code <= 0x1E02A) || // Mn   [5] COMBINING GLAGOLITIC LETTER YO..COMBINING GLAGOLITIC LETTER FITA
  		(0x1E8D0 <= code && code <= 0x1E8D6) || // Mn   [7] MENDE KIKAKUI COMBINING NUMBER TEENS..MENDE KIKAKUI COMBINING NUMBER MILLIONS
  		(0x1E944 <= code && code <= 0x1E94A) || // Mn   [7] ADLAM ALIF LENGTHENER..ADLAM NUKTA
  		(0xE0020 <= code && code <= 0xE007F) || // Cf  [96] TAG SPACE..CANCEL TAG
  		(0xE0100 <= code && code <= 0xE01EF) // Mn [240] VARIATION SELECTOR-17..VARIATION SELECTOR-256
  		){
  			return Extend;
  		}


  		if(
  		(0x1F1E6 <= code && code <= 0x1F1FF) // So  [26] REGIONAL INDICATOR SYMBOL LETTER A..REGIONAL INDICATOR SYMBOL LETTER Z
  		){
  			return Regional_Indicator;
  		}

  		if(
  		0x0903 == code || // Mc       DEVANAGARI SIGN VISARGA
  		0x093B == code || // Mc       DEVANAGARI VOWEL SIGN OOE
  		(0x093E <= code && code <= 0x0940) || // Mc   [3] DEVANAGARI VOWEL SIGN AA..DEVANAGARI VOWEL SIGN II
  		(0x0949 <= code && code <= 0x094C) || // Mc   [4] DEVANAGARI VOWEL SIGN CANDRA O..DEVANAGARI VOWEL SIGN AU
  		(0x094E <= code && code <= 0x094F) || // Mc   [2] DEVANAGARI VOWEL SIGN PRISHTHAMATRA E..DEVANAGARI VOWEL SIGN AW
  		(0x0982 <= code && code <= 0x0983) || // Mc   [2] BENGALI SIGN ANUSVARA..BENGALI SIGN VISARGA
  		(0x09BF <= code && code <= 0x09C0) || // Mc   [2] BENGALI VOWEL SIGN I..BENGALI VOWEL SIGN II
  		(0x09C7 <= code && code <= 0x09C8) || // Mc   [2] BENGALI VOWEL SIGN E..BENGALI VOWEL SIGN AI
  		(0x09CB <= code && code <= 0x09CC) || // Mc   [2] BENGALI VOWEL SIGN O..BENGALI VOWEL SIGN AU
  		0x0A03 == code || // Mc       GURMUKHI SIGN VISARGA
  		(0x0A3E <= code && code <= 0x0A40) || // Mc   [3] GURMUKHI VOWEL SIGN AA..GURMUKHI VOWEL SIGN II
  		0x0A83 == code || // Mc       GUJARATI SIGN VISARGA
  		(0x0ABE <= code && code <= 0x0AC0) || // Mc   [3] GUJARATI VOWEL SIGN AA..GUJARATI VOWEL SIGN II
  		0x0AC9 == code || // Mc       GUJARATI VOWEL SIGN CANDRA O
  		(0x0ACB <= code && code <= 0x0ACC) || // Mc   [2] GUJARATI VOWEL SIGN O..GUJARATI VOWEL SIGN AU
  		(0x0B02 <= code && code <= 0x0B03) || // Mc   [2] ORIYA SIGN ANUSVARA..ORIYA SIGN VISARGA
  		0x0B40 == code || // Mc       ORIYA VOWEL SIGN II
  		(0x0B47 <= code && code <= 0x0B48) || // Mc   [2] ORIYA VOWEL SIGN E..ORIYA VOWEL SIGN AI
  		(0x0B4B <= code && code <= 0x0B4C) || // Mc   [2] ORIYA VOWEL SIGN O..ORIYA VOWEL SIGN AU
  		0x0BBF == code || // Mc       TAMIL VOWEL SIGN I
  		(0x0BC1 <= code && code <= 0x0BC2) || // Mc   [2] TAMIL VOWEL SIGN U..TAMIL VOWEL SIGN UU
  		(0x0BC6 <= code && code <= 0x0BC8) || // Mc   [3] TAMIL VOWEL SIGN E..TAMIL VOWEL SIGN AI
  		(0x0BCA <= code && code <= 0x0BCC) || // Mc   [3] TAMIL VOWEL SIGN O..TAMIL VOWEL SIGN AU
  		(0x0C01 <= code && code <= 0x0C03) || // Mc   [3] TELUGU SIGN CANDRABINDU..TELUGU SIGN VISARGA
  		(0x0C41 <= code && code <= 0x0C44) || // Mc   [4] TELUGU VOWEL SIGN U..TELUGU VOWEL SIGN VOCALIC RR
  		(0x0C82 <= code && code <= 0x0C83) || // Mc   [2] KANNADA SIGN ANUSVARA..KANNADA SIGN VISARGA
  		0x0CBE == code || // Mc       KANNADA VOWEL SIGN AA
  		(0x0CC0 <= code && code <= 0x0CC1) || // Mc   [2] KANNADA VOWEL SIGN II..KANNADA VOWEL SIGN U
  		(0x0CC3 <= code && code <= 0x0CC4) || // Mc   [2] KANNADA VOWEL SIGN VOCALIC R..KANNADA VOWEL SIGN VOCALIC RR
  		(0x0CC7 <= code && code <= 0x0CC8) || // Mc   [2] KANNADA VOWEL SIGN EE..KANNADA VOWEL SIGN AI
  		(0x0CCA <= code && code <= 0x0CCB) || // Mc   [2] KANNADA VOWEL SIGN O..KANNADA VOWEL SIGN OO
  		(0x0D02 <= code && code <= 0x0D03) || // Mc   [2] MALAYALAM SIGN ANUSVARA..MALAYALAM SIGN VISARGA
  		(0x0D3F <= code && code <= 0x0D40) || // Mc   [2] MALAYALAM VOWEL SIGN I..MALAYALAM VOWEL SIGN II
  		(0x0D46 <= code && code <= 0x0D48) || // Mc   [3] MALAYALAM VOWEL SIGN E..MALAYALAM VOWEL SIGN AI
  		(0x0D4A <= code && code <= 0x0D4C) || // Mc   [3] MALAYALAM VOWEL SIGN O..MALAYALAM VOWEL SIGN AU
  		(0x0D82 <= code && code <= 0x0D83) || // Mc   [2] SINHALA SIGN ANUSVARAYA..SINHALA SIGN VISARGAYA
  		(0x0DD0 <= code && code <= 0x0DD1) || // Mc   [2] SINHALA VOWEL SIGN KETTI AEDA-PILLA..SINHALA VOWEL SIGN DIGA AEDA-PILLA
  		(0x0DD8 <= code && code <= 0x0DDE) || // Mc   [7] SINHALA VOWEL SIGN GAETTA-PILLA..SINHALA VOWEL SIGN KOMBUVA HAA GAYANUKITTA
  		(0x0DF2 <= code && code <= 0x0DF3) || // Mc   [2] SINHALA VOWEL SIGN DIGA GAETTA-PILLA..SINHALA VOWEL SIGN DIGA GAYANUKITTA
  		0x0E33 == code || // Lo       THAI CHARACTER SARA AM
  		0x0EB3 == code || // Lo       LAO VOWEL SIGN AM
  		(0x0F3E <= code && code <= 0x0F3F) || // Mc   [2] TIBETAN SIGN YAR TSHES..TIBETAN SIGN MAR TSHES
  		0x0F7F == code || // Mc       TIBETAN SIGN RNAM BCAD
  		0x1031 == code || // Mc       MYANMAR VOWEL SIGN E
  		(0x103B <= code && code <= 0x103C) || // Mc   [2] MYANMAR CONSONANT SIGN MEDIAL YA..MYANMAR CONSONANT SIGN MEDIAL RA
  		(0x1056 <= code && code <= 0x1057) || // Mc   [2] MYANMAR VOWEL SIGN VOCALIC R..MYANMAR VOWEL SIGN VOCALIC RR
  		0x1084 == code || // Mc       MYANMAR VOWEL SIGN SHAN E
  		0x17B6 == code || // Mc       KHMER VOWEL SIGN AA
  		(0x17BE <= code && code <= 0x17C5) || // Mc   [8] KHMER VOWEL SIGN OE..KHMER VOWEL SIGN AU
  		(0x17C7 <= code && code <= 0x17C8) || // Mc   [2] KHMER SIGN REAHMUK..KHMER SIGN YUUKALEAPINTU
  		(0x1923 <= code && code <= 0x1926) || // Mc   [4] LIMBU VOWEL SIGN EE..LIMBU VOWEL SIGN AU
  		(0x1929 <= code && code <= 0x192B) || // Mc   [3] LIMBU SUBJOINED LETTER YA..LIMBU SUBJOINED LETTER WA
  		(0x1930 <= code && code <= 0x1931) || // Mc   [2] LIMBU SMALL LETTER KA..LIMBU SMALL LETTER NGA
  		(0x1933 <= code && code <= 0x1938) || // Mc   [6] LIMBU SMALL LETTER TA..LIMBU SMALL LETTER LA
  		(0x1A19 <= code && code <= 0x1A1A) || // Mc   [2] BUGINESE VOWEL SIGN E..BUGINESE VOWEL SIGN O
  		0x1A55 == code || // Mc       TAI THAM CONSONANT SIGN MEDIAL RA
  		0x1A57 == code || // Mc       TAI THAM CONSONANT SIGN LA TANG LAI
  		(0x1A6D <= code && code <= 0x1A72) || // Mc   [6] TAI THAM VOWEL SIGN OY..TAI THAM VOWEL SIGN THAM AI
  		0x1B04 == code || // Mc       BALINESE SIGN BISAH
  		0x1B35 == code || // Mc       BALINESE VOWEL SIGN TEDUNG
  		0x1B3B == code || // Mc       BALINESE VOWEL SIGN RA REPA TEDUNG
  		(0x1B3D <= code && code <= 0x1B41) || // Mc   [5] BALINESE VOWEL SIGN LA LENGA TEDUNG..BALINESE VOWEL SIGN TALING REPA TEDUNG
  		(0x1B43 <= code && code <= 0x1B44) || // Mc   [2] BALINESE VOWEL SIGN PEPET TEDUNG..BALINESE ADEG ADEG
  		0x1B82 == code || // Mc       SUNDANESE SIGN PANGWISAD
  		0x1BA1 == code || // Mc       SUNDANESE CONSONANT SIGN PAMINGKAL
  		(0x1BA6 <= code && code <= 0x1BA7) || // Mc   [2] SUNDANESE VOWEL SIGN PANAELAENG..SUNDANESE VOWEL SIGN PANOLONG
  		0x1BAA == code || // Mc       SUNDANESE SIGN PAMAAEH
  		0x1BE7 == code || // Mc       BATAK VOWEL SIGN E
  		(0x1BEA <= code && code <= 0x1BEC) || // Mc   [3] BATAK VOWEL SIGN I..BATAK VOWEL SIGN O
  		0x1BEE == code || // Mc       BATAK VOWEL SIGN U
  		(0x1BF2 <= code && code <= 0x1BF3) || // Mc   [2] BATAK PANGOLAT..BATAK PANONGONAN
  		(0x1C24 <= code && code <= 0x1C2B) || // Mc   [8] LEPCHA SUBJOINED LETTER YA..LEPCHA VOWEL SIGN UU
  		(0x1C34 <= code && code <= 0x1C35) || // Mc   [2] LEPCHA CONSONANT SIGN NYIN-DO..LEPCHA CONSONANT SIGN KANG
  		0x1CE1 == code || // Mc       VEDIC TONE ATHARVAVEDIC INDEPENDENT SVARITA
  		(0x1CF2 <= code && code <= 0x1CF3) || // Mc   [2] VEDIC SIGN ARDHAVISARGA..VEDIC SIGN ROTATED ARDHAVISARGA
  		0x1CF7 == code || // Mc       VEDIC SIGN ATIKRAMA
  		(0xA823 <= code && code <= 0xA824) || // Mc   [2] SYLOTI NAGRI VOWEL SIGN A..SYLOTI NAGRI VOWEL SIGN I
  		0xA827 == code || // Mc       SYLOTI NAGRI VOWEL SIGN OO
  		(0xA880 <= code && code <= 0xA881) || // Mc   [2] SAURASHTRA SIGN ANUSVARA..SAURASHTRA SIGN VISARGA
  		(0xA8B4 <= code && code <= 0xA8C3) || // Mc  [16] SAURASHTRA CONSONANT SIGN HAARU..SAURASHTRA VOWEL SIGN AU
  		(0xA952 <= code && code <= 0xA953) || // Mc   [2] REJANG CONSONANT SIGN H..REJANG VIRAMA
  		0xA983 == code || // Mc       JAVANESE SIGN WIGNYAN
  		(0xA9B4 <= code && code <= 0xA9B5) || // Mc   [2] JAVANESE VOWEL SIGN TARUNG..JAVANESE VOWEL SIGN TOLONG
  		(0xA9BA <= code && code <= 0xA9BB) || // Mc   [2] JAVANESE VOWEL SIGN TALING..JAVANESE VOWEL SIGN DIRGA MURE
  		(0xA9BD <= code && code <= 0xA9C0) || // Mc   [4] JAVANESE CONSONANT SIGN KERET..JAVANESE PANGKON
  		(0xAA2F <= code && code <= 0xAA30) || // Mc   [2] CHAM VOWEL SIGN O..CHAM VOWEL SIGN AI
  		(0xAA33 <= code && code <= 0xAA34) || // Mc   [2] CHAM CONSONANT SIGN YA..CHAM CONSONANT SIGN RA
  		0xAA4D == code || // Mc       CHAM CONSONANT SIGN FINAL H
  		0xAAEB == code || // Mc       MEETEI MAYEK VOWEL SIGN II
  		(0xAAEE <= code && code <= 0xAAEF) || // Mc   [2] MEETEI MAYEK VOWEL SIGN AU..MEETEI MAYEK VOWEL SIGN AAU
  		0xAAF5 == code || // Mc       MEETEI MAYEK VOWEL SIGN VISARGA
  		(0xABE3 <= code && code <= 0xABE4) || // Mc   [2] MEETEI MAYEK VOWEL SIGN ONAP..MEETEI MAYEK VOWEL SIGN INAP
  		(0xABE6 <= code && code <= 0xABE7) || // Mc   [2] MEETEI MAYEK VOWEL SIGN YENAP..MEETEI MAYEK VOWEL SIGN SOUNAP
  		(0xABE9 <= code && code <= 0xABEA) || // Mc   [2] MEETEI MAYEK VOWEL SIGN CHEINAP..MEETEI MAYEK VOWEL SIGN NUNG
  		0xABEC == code || // Mc       MEETEI MAYEK LUM IYEK
  		0x11000 == code || // Mc       BRAHMI SIGN CANDRABINDU
  		0x11002 == code || // Mc       BRAHMI SIGN VISARGA
  		0x11082 == code || // Mc       KAITHI SIGN VISARGA
  		(0x110B0 <= code && code <= 0x110B2) || // Mc   [3] KAITHI VOWEL SIGN AA..KAITHI VOWEL SIGN II
  		(0x110B7 <= code && code <= 0x110B8) || // Mc   [2] KAITHI VOWEL SIGN O..KAITHI VOWEL SIGN AU
  		0x1112C == code || // Mc       CHAKMA VOWEL SIGN E
  		0x11182 == code || // Mc       SHARADA SIGN VISARGA
  		(0x111B3 <= code && code <= 0x111B5) || // Mc   [3] SHARADA VOWEL SIGN AA..SHARADA VOWEL SIGN II
  		(0x111BF <= code && code <= 0x111C0) || // Mc   [2] SHARADA VOWEL SIGN AU..SHARADA SIGN VIRAMA
  		(0x1122C <= code && code <= 0x1122E) || // Mc   [3] KHOJKI VOWEL SIGN AA..KHOJKI VOWEL SIGN II
  		(0x11232 <= code && code <= 0x11233) || // Mc   [2] KHOJKI VOWEL SIGN O..KHOJKI VOWEL SIGN AU
  		0x11235 == code || // Mc       KHOJKI SIGN VIRAMA
  		(0x112E0 <= code && code <= 0x112E2) || // Mc   [3] KHUDAWADI VOWEL SIGN AA..KHUDAWADI VOWEL SIGN II
  		(0x11302 <= code && code <= 0x11303) || // Mc   [2] GRANTHA SIGN ANUSVARA..GRANTHA SIGN VISARGA
  		0x1133F == code || // Mc       GRANTHA VOWEL SIGN I
  		(0x11341 <= code && code <= 0x11344) || // Mc   [4] GRANTHA VOWEL SIGN U..GRANTHA VOWEL SIGN VOCALIC RR
  		(0x11347 <= code && code <= 0x11348) || // Mc   [2] GRANTHA VOWEL SIGN EE..GRANTHA VOWEL SIGN AI
  		(0x1134B <= code && code <= 0x1134D) || // Mc   [3] GRANTHA VOWEL SIGN OO..GRANTHA SIGN VIRAMA
  		(0x11362 <= code && code <= 0x11363) || // Mc   [2] GRANTHA VOWEL SIGN VOCALIC L..GRANTHA VOWEL SIGN VOCALIC LL
  		(0x11435 <= code && code <= 0x11437) || // Mc   [3] NEWA VOWEL SIGN AA..NEWA VOWEL SIGN II
  		(0x11440 <= code && code <= 0x11441) || // Mc   [2] NEWA VOWEL SIGN O..NEWA VOWEL SIGN AU
  		0x11445 == code || // Mc       NEWA SIGN VISARGA
  		(0x114B1 <= code && code <= 0x114B2) || // Mc   [2] TIRHUTA VOWEL SIGN I..TIRHUTA VOWEL SIGN II
  		0x114B9 == code || // Mc       TIRHUTA VOWEL SIGN E
  		(0x114BB <= code && code <= 0x114BC) || // Mc   [2] TIRHUTA VOWEL SIGN AI..TIRHUTA VOWEL SIGN O
  		0x114BE == code || // Mc       TIRHUTA VOWEL SIGN AU
  		0x114C1 == code || // Mc       TIRHUTA SIGN VISARGA
  		(0x115B0 <= code && code <= 0x115B1) || // Mc   [2] SIDDHAM VOWEL SIGN I..SIDDHAM VOWEL SIGN II
  		(0x115B8 <= code && code <= 0x115BB) || // Mc   [4] SIDDHAM VOWEL SIGN E..SIDDHAM VOWEL SIGN AU
  		0x115BE == code || // Mc       SIDDHAM SIGN VISARGA
  		(0x11630 <= code && code <= 0x11632) || // Mc   [3] MODI VOWEL SIGN AA..MODI VOWEL SIGN II
  		(0x1163B <= code && code <= 0x1163C) || // Mc   [2] MODI VOWEL SIGN O..MODI VOWEL SIGN AU
  		0x1163E == code || // Mc       MODI SIGN VISARGA
  		0x116AC == code || // Mc       TAKRI SIGN VISARGA
  		(0x116AE <= code && code <= 0x116AF) || // Mc   [2] TAKRI VOWEL SIGN I..TAKRI VOWEL SIGN II
  		0x116B6 == code || // Mc       TAKRI SIGN VIRAMA
  		(0x11720 <= code && code <= 0x11721) || // Mc   [2] AHOM VOWEL SIGN A..AHOM VOWEL SIGN AA
  		0x11726 == code || // Mc       AHOM VOWEL SIGN E
  		(0x11A07 <= code && code <= 0x11A08) || // Mc   [2] ZANABAZAR SQUARE VOWEL SIGN AI..ZANABAZAR SQUARE VOWEL SIGN AU
  		0x11A39 == code || // Mc       ZANABAZAR SQUARE SIGN VISARGA
  		(0x11A57 <= code && code <= 0x11A58) || // Mc   [2] SOYOMBO VOWEL SIGN AI..SOYOMBO VOWEL SIGN AU
  		0x11A97 == code || // Mc       SOYOMBO SIGN VISARGA
  		0x11C2F == code || // Mc       BHAIKSUKI VOWEL SIGN AA
  		0x11C3E == code || // Mc       BHAIKSUKI SIGN VISARGA
  		0x11CA9 == code || // Mc       MARCHEN SUBJOINED LETTER YA
  		0x11CB1 == code || // Mc       MARCHEN VOWEL SIGN I
  		0x11CB4 == code || // Mc       MARCHEN VOWEL SIGN O
  		(0x16F51 <= code && code <= 0x16F7E) || // Mc  [46] MIAO SIGN ASPIRATION..MIAO VOWEL SIGN NG
  		0x1D166 == code || // Mc       MUSICAL SYMBOL COMBINING SPRECHGESANG STEM
  		0x1D16D == code // Mc       MUSICAL SYMBOL COMBINING AUGMENTATION DOT
  		){
  			return SpacingMark;
  		}


  		if(
  		(0x1100 <= code && code <= 0x115F) || // Lo  [96] HANGUL CHOSEONG KIYEOK..HANGUL CHOSEONG FILLER
  		(0xA960 <= code && code <= 0xA97C) // Lo  [29] HANGUL CHOSEONG TIKEUT-MIEUM..HANGUL CHOSEONG SSANGYEORINHIEUH
  		){
  			return L;
  		}

  		if(
  		(0x1160 <= code && code <= 0x11A7) || // Lo  [72] HANGUL JUNGSEONG FILLER..HANGUL JUNGSEONG O-YAE
  		(0xD7B0 <= code && code <= 0xD7C6) // Lo  [23] HANGUL JUNGSEONG O-YEO..HANGUL JUNGSEONG ARAEA-E
  		){
  			return V;
  		}


  		if(
  		(0x11A8 <= code && code <= 0x11FF) || // Lo  [88] HANGUL JONGSEONG KIYEOK..HANGUL JONGSEONG SSANGNIEUN
  		(0xD7CB <= code && code <= 0xD7FB) // Lo  [49] HANGUL JONGSEONG NIEUN-RIEUL..HANGUL JONGSEONG PHIEUPH-THIEUTH
  		){
  			return T;
  		}

  		if(
  		0xAC00 == code || // Lo       HANGUL SYLLABLE GA
  		0xAC1C == code || // Lo       HANGUL SYLLABLE GAE
  		0xAC38 == code || // Lo       HANGUL SYLLABLE GYA
  		0xAC54 == code || // Lo       HANGUL SYLLABLE GYAE
  		0xAC70 == code || // Lo       HANGUL SYLLABLE GEO
  		0xAC8C == code || // Lo       HANGUL SYLLABLE GE
  		0xACA8 == code || // Lo       HANGUL SYLLABLE GYEO
  		0xACC4 == code || // Lo       HANGUL SYLLABLE GYE
  		0xACE0 == code || // Lo       HANGUL SYLLABLE GO
  		0xACFC == code || // Lo       HANGUL SYLLABLE GWA
  		0xAD18 == code || // Lo       HANGUL SYLLABLE GWAE
  		0xAD34 == code || // Lo       HANGUL SYLLABLE GOE
  		0xAD50 == code || // Lo       HANGUL SYLLABLE GYO
  		0xAD6C == code || // Lo       HANGUL SYLLABLE GU
  		0xAD88 == code || // Lo       HANGUL SYLLABLE GWEO
  		0xADA4 == code || // Lo       HANGUL SYLLABLE GWE
  		0xADC0 == code || // Lo       HANGUL SYLLABLE GWI
  		0xADDC == code || // Lo       HANGUL SYLLABLE GYU
  		0xADF8 == code || // Lo       HANGUL SYLLABLE GEU
  		0xAE14 == code || // Lo       HANGUL SYLLABLE GYI
  		0xAE30 == code || // Lo       HANGUL SYLLABLE GI
  		0xAE4C == code || // Lo       HANGUL SYLLABLE GGA
  		0xAE68 == code || // Lo       HANGUL SYLLABLE GGAE
  		0xAE84 == code || // Lo       HANGUL SYLLABLE GGYA
  		0xAEA0 == code || // Lo       HANGUL SYLLABLE GGYAE
  		0xAEBC == code || // Lo       HANGUL SYLLABLE GGEO
  		0xAED8 == code || // Lo       HANGUL SYLLABLE GGE
  		0xAEF4 == code || // Lo       HANGUL SYLLABLE GGYEO
  		0xAF10 == code || // Lo       HANGUL SYLLABLE GGYE
  		0xAF2C == code || // Lo       HANGUL SYLLABLE GGO
  		0xAF48 == code || // Lo       HANGUL SYLLABLE GGWA
  		0xAF64 == code || // Lo       HANGUL SYLLABLE GGWAE
  		0xAF80 == code || // Lo       HANGUL SYLLABLE GGOE
  		0xAF9C == code || // Lo       HANGUL SYLLABLE GGYO
  		0xAFB8 == code || // Lo       HANGUL SYLLABLE GGU
  		0xAFD4 == code || // Lo       HANGUL SYLLABLE GGWEO
  		0xAFF0 == code || // Lo       HANGUL SYLLABLE GGWE
  		0xB00C == code || // Lo       HANGUL SYLLABLE GGWI
  		0xB028 == code || // Lo       HANGUL SYLLABLE GGYU
  		0xB044 == code || // Lo       HANGUL SYLLABLE GGEU
  		0xB060 == code || // Lo       HANGUL SYLLABLE GGYI
  		0xB07C == code || // Lo       HANGUL SYLLABLE GGI
  		0xB098 == code || // Lo       HANGUL SYLLABLE NA
  		0xB0B4 == code || // Lo       HANGUL SYLLABLE NAE
  		0xB0D0 == code || // Lo       HANGUL SYLLABLE NYA
  		0xB0EC == code || // Lo       HANGUL SYLLABLE NYAE
  		0xB108 == code || // Lo       HANGUL SYLLABLE NEO
  		0xB124 == code || // Lo       HANGUL SYLLABLE NE
  		0xB140 == code || // Lo       HANGUL SYLLABLE NYEO
  		0xB15C == code || // Lo       HANGUL SYLLABLE NYE
  		0xB178 == code || // Lo       HANGUL SYLLABLE NO
  		0xB194 == code || // Lo       HANGUL SYLLABLE NWA
  		0xB1B0 == code || // Lo       HANGUL SYLLABLE NWAE
  		0xB1CC == code || // Lo       HANGUL SYLLABLE NOE
  		0xB1E8 == code || // Lo       HANGUL SYLLABLE NYO
  		0xB204 == code || // Lo       HANGUL SYLLABLE NU
  		0xB220 == code || // Lo       HANGUL SYLLABLE NWEO
  		0xB23C == code || // Lo       HANGUL SYLLABLE NWE
  		0xB258 == code || // Lo       HANGUL SYLLABLE NWI
  		0xB274 == code || // Lo       HANGUL SYLLABLE NYU
  		0xB290 == code || // Lo       HANGUL SYLLABLE NEU
  		0xB2AC == code || // Lo       HANGUL SYLLABLE NYI
  		0xB2C8 == code || // Lo       HANGUL SYLLABLE NI
  		0xB2E4 == code || // Lo       HANGUL SYLLABLE DA
  		0xB300 == code || // Lo       HANGUL SYLLABLE DAE
  		0xB31C == code || // Lo       HANGUL SYLLABLE DYA
  		0xB338 == code || // Lo       HANGUL SYLLABLE DYAE
  		0xB354 == code || // Lo       HANGUL SYLLABLE DEO
  		0xB370 == code || // Lo       HANGUL SYLLABLE DE
  		0xB38C == code || // Lo       HANGUL SYLLABLE DYEO
  		0xB3A8 == code || // Lo       HANGUL SYLLABLE DYE
  		0xB3C4 == code || // Lo       HANGUL SYLLABLE DO
  		0xB3E0 == code || // Lo       HANGUL SYLLABLE DWA
  		0xB3FC == code || // Lo       HANGUL SYLLABLE DWAE
  		0xB418 == code || // Lo       HANGUL SYLLABLE DOE
  		0xB434 == code || // Lo       HANGUL SYLLABLE DYO
  		0xB450 == code || // Lo       HANGUL SYLLABLE DU
  		0xB46C == code || // Lo       HANGUL SYLLABLE DWEO
  		0xB488 == code || // Lo       HANGUL SYLLABLE DWE
  		0xB4A4 == code || // Lo       HANGUL SYLLABLE DWI
  		0xB4C0 == code || // Lo       HANGUL SYLLABLE DYU
  		0xB4DC == code || // Lo       HANGUL SYLLABLE DEU
  		0xB4F8 == code || // Lo       HANGUL SYLLABLE DYI
  		0xB514 == code || // Lo       HANGUL SYLLABLE DI
  		0xB530 == code || // Lo       HANGUL SYLLABLE DDA
  		0xB54C == code || // Lo       HANGUL SYLLABLE DDAE
  		0xB568 == code || // Lo       HANGUL SYLLABLE DDYA
  		0xB584 == code || // Lo       HANGUL SYLLABLE DDYAE
  		0xB5A0 == code || // Lo       HANGUL SYLLABLE DDEO
  		0xB5BC == code || // Lo       HANGUL SYLLABLE DDE
  		0xB5D8 == code || // Lo       HANGUL SYLLABLE DDYEO
  		0xB5F4 == code || // Lo       HANGUL SYLLABLE DDYE
  		0xB610 == code || // Lo       HANGUL SYLLABLE DDO
  		0xB62C == code || // Lo       HANGUL SYLLABLE DDWA
  		0xB648 == code || // Lo       HANGUL SYLLABLE DDWAE
  		0xB664 == code || // Lo       HANGUL SYLLABLE DDOE
  		0xB680 == code || // Lo       HANGUL SYLLABLE DDYO
  		0xB69C == code || // Lo       HANGUL SYLLABLE DDU
  		0xB6B8 == code || // Lo       HANGUL SYLLABLE DDWEO
  		0xB6D4 == code || // Lo       HANGUL SYLLABLE DDWE
  		0xB6F0 == code || // Lo       HANGUL SYLLABLE DDWI
  		0xB70C == code || // Lo       HANGUL SYLLABLE DDYU
  		0xB728 == code || // Lo       HANGUL SYLLABLE DDEU
  		0xB744 == code || // Lo       HANGUL SYLLABLE DDYI
  		0xB760 == code || // Lo       HANGUL SYLLABLE DDI
  		0xB77C == code || // Lo       HANGUL SYLLABLE RA
  		0xB798 == code || // Lo       HANGUL SYLLABLE RAE
  		0xB7B4 == code || // Lo       HANGUL SYLLABLE RYA
  		0xB7D0 == code || // Lo       HANGUL SYLLABLE RYAE
  		0xB7EC == code || // Lo       HANGUL SYLLABLE REO
  		0xB808 == code || // Lo       HANGUL SYLLABLE RE
  		0xB824 == code || // Lo       HANGUL SYLLABLE RYEO
  		0xB840 == code || // Lo       HANGUL SYLLABLE RYE
  		0xB85C == code || // Lo       HANGUL SYLLABLE RO
  		0xB878 == code || // Lo       HANGUL SYLLABLE RWA
  		0xB894 == code || // Lo       HANGUL SYLLABLE RWAE
  		0xB8B0 == code || // Lo       HANGUL SYLLABLE ROE
  		0xB8CC == code || // Lo       HANGUL SYLLABLE RYO
  		0xB8E8 == code || // Lo       HANGUL SYLLABLE RU
  		0xB904 == code || // Lo       HANGUL SYLLABLE RWEO
  		0xB920 == code || // Lo       HANGUL SYLLABLE RWE
  		0xB93C == code || // Lo       HANGUL SYLLABLE RWI
  		0xB958 == code || // Lo       HANGUL SYLLABLE RYU
  		0xB974 == code || // Lo       HANGUL SYLLABLE REU
  		0xB990 == code || // Lo       HANGUL SYLLABLE RYI
  		0xB9AC == code || // Lo       HANGUL SYLLABLE RI
  		0xB9C8 == code || // Lo       HANGUL SYLLABLE MA
  		0xB9E4 == code || // Lo       HANGUL SYLLABLE MAE
  		0xBA00 == code || // Lo       HANGUL SYLLABLE MYA
  		0xBA1C == code || // Lo       HANGUL SYLLABLE MYAE
  		0xBA38 == code || // Lo       HANGUL SYLLABLE MEO
  		0xBA54 == code || // Lo       HANGUL SYLLABLE ME
  		0xBA70 == code || // Lo       HANGUL SYLLABLE MYEO
  		0xBA8C == code || // Lo       HANGUL SYLLABLE MYE
  		0xBAA8 == code || // Lo       HANGUL SYLLABLE MO
  		0xBAC4 == code || // Lo       HANGUL SYLLABLE MWA
  		0xBAE0 == code || // Lo       HANGUL SYLLABLE MWAE
  		0xBAFC == code || // Lo       HANGUL SYLLABLE MOE
  		0xBB18 == code || // Lo       HANGUL SYLLABLE MYO
  		0xBB34 == code || // Lo       HANGUL SYLLABLE MU
  		0xBB50 == code || // Lo       HANGUL SYLLABLE MWEO
  		0xBB6C == code || // Lo       HANGUL SYLLABLE MWE
  		0xBB88 == code || // Lo       HANGUL SYLLABLE MWI
  		0xBBA4 == code || // Lo       HANGUL SYLLABLE MYU
  		0xBBC0 == code || // Lo       HANGUL SYLLABLE MEU
  		0xBBDC == code || // Lo       HANGUL SYLLABLE MYI
  		0xBBF8 == code || // Lo       HANGUL SYLLABLE MI
  		0xBC14 == code || // Lo       HANGUL SYLLABLE BA
  		0xBC30 == code || // Lo       HANGUL SYLLABLE BAE
  		0xBC4C == code || // Lo       HANGUL SYLLABLE BYA
  		0xBC68 == code || // Lo       HANGUL SYLLABLE BYAE
  		0xBC84 == code || // Lo       HANGUL SYLLABLE BEO
  		0xBCA0 == code || // Lo       HANGUL SYLLABLE BE
  		0xBCBC == code || // Lo       HANGUL SYLLABLE BYEO
  		0xBCD8 == code || // Lo       HANGUL SYLLABLE BYE
  		0xBCF4 == code || // Lo       HANGUL SYLLABLE BO
  		0xBD10 == code || // Lo       HANGUL SYLLABLE BWA
  		0xBD2C == code || // Lo       HANGUL SYLLABLE BWAE
  		0xBD48 == code || // Lo       HANGUL SYLLABLE BOE
  		0xBD64 == code || // Lo       HANGUL SYLLABLE BYO
  		0xBD80 == code || // Lo       HANGUL SYLLABLE BU
  		0xBD9C == code || // Lo       HANGUL SYLLABLE BWEO
  		0xBDB8 == code || // Lo       HANGUL SYLLABLE BWE
  		0xBDD4 == code || // Lo       HANGUL SYLLABLE BWI
  		0xBDF0 == code || // Lo       HANGUL SYLLABLE BYU
  		0xBE0C == code || // Lo       HANGUL SYLLABLE BEU
  		0xBE28 == code || // Lo       HANGUL SYLLABLE BYI
  		0xBE44 == code || // Lo       HANGUL SYLLABLE BI
  		0xBE60 == code || // Lo       HANGUL SYLLABLE BBA
  		0xBE7C == code || // Lo       HANGUL SYLLABLE BBAE
  		0xBE98 == code || // Lo       HANGUL SYLLABLE BBYA
  		0xBEB4 == code || // Lo       HANGUL SYLLABLE BBYAE
  		0xBED0 == code || // Lo       HANGUL SYLLABLE BBEO
  		0xBEEC == code || // Lo       HANGUL SYLLABLE BBE
  		0xBF08 == code || // Lo       HANGUL SYLLABLE BBYEO
  		0xBF24 == code || // Lo       HANGUL SYLLABLE BBYE
  		0xBF40 == code || // Lo       HANGUL SYLLABLE BBO
  		0xBF5C == code || // Lo       HANGUL SYLLABLE BBWA
  		0xBF78 == code || // Lo       HANGUL SYLLABLE BBWAE
  		0xBF94 == code || // Lo       HANGUL SYLLABLE BBOE
  		0xBFB0 == code || // Lo       HANGUL SYLLABLE BBYO
  		0xBFCC == code || // Lo       HANGUL SYLLABLE BBU
  		0xBFE8 == code || // Lo       HANGUL SYLLABLE BBWEO
  		0xC004 == code || // Lo       HANGUL SYLLABLE BBWE
  		0xC020 == code || // Lo       HANGUL SYLLABLE BBWI
  		0xC03C == code || // Lo       HANGUL SYLLABLE BBYU
  		0xC058 == code || // Lo       HANGUL SYLLABLE BBEU
  		0xC074 == code || // Lo       HANGUL SYLLABLE BBYI
  		0xC090 == code || // Lo       HANGUL SYLLABLE BBI
  		0xC0AC == code || // Lo       HANGUL SYLLABLE SA
  		0xC0C8 == code || // Lo       HANGUL SYLLABLE SAE
  		0xC0E4 == code || // Lo       HANGUL SYLLABLE SYA
  		0xC100 == code || // Lo       HANGUL SYLLABLE SYAE
  		0xC11C == code || // Lo       HANGUL SYLLABLE SEO
  		0xC138 == code || // Lo       HANGUL SYLLABLE SE
  		0xC154 == code || // Lo       HANGUL SYLLABLE SYEO
  		0xC170 == code || // Lo       HANGUL SYLLABLE SYE
  		0xC18C == code || // Lo       HANGUL SYLLABLE SO
  		0xC1A8 == code || // Lo       HANGUL SYLLABLE SWA
  		0xC1C4 == code || // Lo       HANGUL SYLLABLE SWAE
  		0xC1E0 == code || // Lo       HANGUL SYLLABLE SOE
  		0xC1FC == code || // Lo       HANGUL SYLLABLE SYO
  		0xC218 == code || // Lo       HANGUL SYLLABLE SU
  		0xC234 == code || // Lo       HANGUL SYLLABLE SWEO
  		0xC250 == code || // Lo       HANGUL SYLLABLE SWE
  		0xC26C == code || // Lo       HANGUL SYLLABLE SWI
  		0xC288 == code || // Lo       HANGUL SYLLABLE SYU
  		0xC2A4 == code || // Lo       HANGUL SYLLABLE SEU
  		0xC2C0 == code || // Lo       HANGUL SYLLABLE SYI
  		0xC2DC == code || // Lo       HANGUL SYLLABLE SI
  		0xC2F8 == code || // Lo       HANGUL SYLLABLE SSA
  		0xC314 == code || // Lo       HANGUL SYLLABLE SSAE
  		0xC330 == code || // Lo       HANGUL SYLLABLE SSYA
  		0xC34C == code || // Lo       HANGUL SYLLABLE SSYAE
  		0xC368 == code || // Lo       HANGUL SYLLABLE SSEO
  		0xC384 == code || // Lo       HANGUL SYLLABLE SSE
  		0xC3A0 == code || // Lo       HANGUL SYLLABLE SSYEO
  		0xC3BC == code || // Lo       HANGUL SYLLABLE SSYE
  		0xC3D8 == code || // Lo       HANGUL SYLLABLE SSO
  		0xC3F4 == code || // Lo       HANGUL SYLLABLE SSWA
  		0xC410 == code || // Lo       HANGUL SYLLABLE SSWAE
  		0xC42C == code || // Lo       HANGUL SYLLABLE SSOE
  		0xC448 == code || // Lo       HANGUL SYLLABLE SSYO
  		0xC464 == code || // Lo       HANGUL SYLLABLE SSU
  		0xC480 == code || // Lo       HANGUL SYLLABLE SSWEO
  		0xC49C == code || // Lo       HANGUL SYLLABLE SSWE
  		0xC4B8 == code || // Lo       HANGUL SYLLABLE SSWI
  		0xC4D4 == code || // Lo       HANGUL SYLLABLE SSYU
  		0xC4F0 == code || // Lo       HANGUL SYLLABLE SSEU
  		0xC50C == code || // Lo       HANGUL SYLLABLE SSYI
  		0xC528 == code || // Lo       HANGUL SYLLABLE SSI
  		0xC544 == code || // Lo       HANGUL SYLLABLE A
  		0xC560 == code || // Lo       HANGUL SYLLABLE AE
  		0xC57C == code || // Lo       HANGUL SYLLABLE YA
  		0xC598 == code || // Lo       HANGUL SYLLABLE YAE
  		0xC5B4 == code || // Lo       HANGUL SYLLABLE EO
  		0xC5D0 == code || // Lo       HANGUL SYLLABLE E
  		0xC5EC == code || // Lo       HANGUL SYLLABLE YEO
  		0xC608 == code || // Lo       HANGUL SYLLABLE YE
  		0xC624 == code || // Lo       HANGUL SYLLABLE O
  		0xC640 == code || // Lo       HANGUL SYLLABLE WA
  		0xC65C == code || // Lo       HANGUL SYLLABLE WAE
  		0xC678 == code || // Lo       HANGUL SYLLABLE OE
  		0xC694 == code || // Lo       HANGUL SYLLABLE YO
  		0xC6B0 == code || // Lo       HANGUL SYLLABLE U
  		0xC6CC == code || // Lo       HANGUL SYLLABLE WEO
  		0xC6E8 == code || // Lo       HANGUL SYLLABLE WE
  		0xC704 == code || // Lo       HANGUL SYLLABLE WI
  		0xC720 == code || // Lo       HANGUL SYLLABLE YU
  		0xC73C == code || // Lo       HANGUL SYLLABLE EU
  		0xC758 == code || // Lo       HANGUL SYLLABLE YI
  		0xC774 == code || // Lo       HANGUL SYLLABLE I
  		0xC790 == code || // Lo       HANGUL SYLLABLE JA
  		0xC7AC == code || // Lo       HANGUL SYLLABLE JAE
  		0xC7C8 == code || // Lo       HANGUL SYLLABLE JYA
  		0xC7E4 == code || // Lo       HANGUL SYLLABLE JYAE
  		0xC800 == code || // Lo       HANGUL SYLLABLE JEO
  		0xC81C == code || // Lo       HANGUL SYLLABLE JE
  		0xC838 == code || // Lo       HANGUL SYLLABLE JYEO
  		0xC854 == code || // Lo       HANGUL SYLLABLE JYE
  		0xC870 == code || // Lo       HANGUL SYLLABLE JO
  		0xC88C == code || // Lo       HANGUL SYLLABLE JWA
  		0xC8A8 == code || // Lo       HANGUL SYLLABLE JWAE
  		0xC8C4 == code || // Lo       HANGUL SYLLABLE JOE
  		0xC8E0 == code || // Lo       HANGUL SYLLABLE JYO
  		0xC8FC == code || // Lo       HANGUL SYLLABLE JU
  		0xC918 == code || // Lo       HANGUL SYLLABLE JWEO
  		0xC934 == code || // Lo       HANGUL SYLLABLE JWE
  		0xC950 == code || // Lo       HANGUL SYLLABLE JWI
  		0xC96C == code || // Lo       HANGUL SYLLABLE JYU
  		0xC988 == code || // Lo       HANGUL SYLLABLE JEU
  		0xC9A4 == code || // Lo       HANGUL SYLLABLE JYI
  		0xC9C0 == code || // Lo       HANGUL SYLLABLE JI
  		0xC9DC == code || // Lo       HANGUL SYLLABLE JJA
  		0xC9F8 == code || // Lo       HANGUL SYLLABLE JJAE
  		0xCA14 == code || // Lo       HANGUL SYLLABLE JJYA
  		0xCA30 == code || // Lo       HANGUL SYLLABLE JJYAE
  		0xCA4C == code || // Lo       HANGUL SYLLABLE JJEO
  		0xCA68 == code || // Lo       HANGUL SYLLABLE JJE
  		0xCA84 == code || // Lo       HANGUL SYLLABLE JJYEO
  		0xCAA0 == code || // Lo       HANGUL SYLLABLE JJYE
  		0xCABC == code || // Lo       HANGUL SYLLABLE JJO
  		0xCAD8 == code || // Lo       HANGUL SYLLABLE JJWA
  		0xCAF4 == code || // Lo       HANGUL SYLLABLE JJWAE
  		0xCB10 == code || // Lo       HANGUL SYLLABLE JJOE
  		0xCB2C == code || // Lo       HANGUL SYLLABLE JJYO
  		0xCB48 == code || // Lo       HANGUL SYLLABLE JJU
  		0xCB64 == code || // Lo       HANGUL SYLLABLE JJWEO
  		0xCB80 == code || // Lo       HANGUL SYLLABLE JJWE
  		0xCB9C == code || // Lo       HANGUL SYLLABLE JJWI
  		0xCBB8 == code || // Lo       HANGUL SYLLABLE JJYU
  		0xCBD4 == code || // Lo       HANGUL SYLLABLE JJEU
  		0xCBF0 == code || // Lo       HANGUL SYLLABLE JJYI
  		0xCC0C == code || // Lo       HANGUL SYLLABLE JJI
  		0xCC28 == code || // Lo       HANGUL SYLLABLE CA
  		0xCC44 == code || // Lo       HANGUL SYLLABLE CAE
  		0xCC60 == code || // Lo       HANGUL SYLLABLE CYA
  		0xCC7C == code || // Lo       HANGUL SYLLABLE CYAE
  		0xCC98 == code || // Lo       HANGUL SYLLABLE CEO
  		0xCCB4 == code || // Lo       HANGUL SYLLABLE CE
  		0xCCD0 == code || // Lo       HANGUL SYLLABLE CYEO
  		0xCCEC == code || // Lo       HANGUL SYLLABLE CYE
  		0xCD08 == code || // Lo       HANGUL SYLLABLE CO
  		0xCD24 == code || // Lo       HANGUL SYLLABLE CWA
  		0xCD40 == code || // Lo       HANGUL SYLLABLE CWAE
  		0xCD5C == code || // Lo       HANGUL SYLLABLE COE
  		0xCD78 == code || // Lo       HANGUL SYLLABLE CYO
  		0xCD94 == code || // Lo       HANGUL SYLLABLE CU
  		0xCDB0 == code || // Lo       HANGUL SYLLABLE CWEO
  		0xCDCC == code || // Lo       HANGUL SYLLABLE CWE
  		0xCDE8 == code || // Lo       HANGUL SYLLABLE CWI
  		0xCE04 == code || // Lo       HANGUL SYLLABLE CYU
  		0xCE20 == code || // Lo       HANGUL SYLLABLE CEU
  		0xCE3C == code || // Lo       HANGUL SYLLABLE CYI
  		0xCE58 == code || // Lo       HANGUL SYLLABLE CI
  		0xCE74 == code || // Lo       HANGUL SYLLABLE KA
  		0xCE90 == code || // Lo       HANGUL SYLLABLE KAE
  		0xCEAC == code || // Lo       HANGUL SYLLABLE KYA
  		0xCEC8 == code || // Lo       HANGUL SYLLABLE KYAE
  		0xCEE4 == code || // Lo       HANGUL SYLLABLE KEO
  		0xCF00 == code || // Lo       HANGUL SYLLABLE KE
  		0xCF1C == code || // Lo       HANGUL SYLLABLE KYEO
  		0xCF38 == code || // Lo       HANGUL SYLLABLE KYE
  		0xCF54 == code || // Lo       HANGUL SYLLABLE KO
  		0xCF70 == code || // Lo       HANGUL SYLLABLE KWA
  		0xCF8C == code || // Lo       HANGUL SYLLABLE KWAE
  		0xCFA8 == code || // Lo       HANGUL SYLLABLE KOE
  		0xCFC4 == code || // Lo       HANGUL SYLLABLE KYO
  		0xCFE0 == code || // Lo       HANGUL SYLLABLE KU
  		0xCFFC == code || // Lo       HANGUL SYLLABLE KWEO
  		0xD018 == code || // Lo       HANGUL SYLLABLE KWE
  		0xD034 == code || // Lo       HANGUL SYLLABLE KWI
  		0xD050 == code || // Lo       HANGUL SYLLABLE KYU
  		0xD06C == code || // Lo       HANGUL SYLLABLE KEU
  		0xD088 == code || // Lo       HANGUL SYLLABLE KYI
  		0xD0A4 == code || // Lo       HANGUL SYLLABLE KI
  		0xD0C0 == code || // Lo       HANGUL SYLLABLE TA
  		0xD0DC == code || // Lo       HANGUL SYLLABLE TAE
  		0xD0F8 == code || // Lo       HANGUL SYLLABLE TYA
  		0xD114 == code || // Lo       HANGUL SYLLABLE TYAE
  		0xD130 == code || // Lo       HANGUL SYLLABLE TEO
  		0xD14C == code || // Lo       HANGUL SYLLABLE TE
  		0xD168 == code || // Lo       HANGUL SYLLABLE TYEO
  		0xD184 == code || // Lo       HANGUL SYLLABLE TYE
  		0xD1A0 == code || // Lo       HANGUL SYLLABLE TO
  		0xD1BC == code || // Lo       HANGUL SYLLABLE TWA
  		0xD1D8 == code || // Lo       HANGUL SYLLABLE TWAE
  		0xD1F4 == code || // Lo       HANGUL SYLLABLE TOE
  		0xD210 == code || // Lo       HANGUL SYLLABLE TYO
  		0xD22C == code || // Lo       HANGUL SYLLABLE TU
  		0xD248 == code || // Lo       HANGUL SYLLABLE TWEO
  		0xD264 == code || // Lo       HANGUL SYLLABLE TWE
  		0xD280 == code || // Lo       HANGUL SYLLABLE TWI
  		0xD29C == code || // Lo       HANGUL SYLLABLE TYU
  		0xD2B8 == code || // Lo       HANGUL SYLLABLE TEU
  		0xD2D4 == code || // Lo       HANGUL SYLLABLE TYI
  		0xD2F0 == code || // Lo       HANGUL SYLLABLE TI
  		0xD30C == code || // Lo       HANGUL SYLLABLE PA
  		0xD328 == code || // Lo       HANGUL SYLLABLE PAE
  		0xD344 == code || // Lo       HANGUL SYLLABLE PYA
  		0xD360 == code || // Lo       HANGUL SYLLABLE PYAE
  		0xD37C == code || // Lo       HANGUL SYLLABLE PEO
  		0xD398 == code || // Lo       HANGUL SYLLABLE PE
  		0xD3B4 == code || // Lo       HANGUL SYLLABLE PYEO
  		0xD3D0 == code || // Lo       HANGUL SYLLABLE PYE
  		0xD3EC == code || // Lo       HANGUL SYLLABLE PO
  		0xD408 == code || // Lo       HANGUL SYLLABLE PWA
  		0xD424 == code || // Lo       HANGUL SYLLABLE PWAE
  		0xD440 == code || // Lo       HANGUL SYLLABLE POE
  		0xD45C == code || // Lo       HANGUL SYLLABLE PYO
  		0xD478 == code || // Lo       HANGUL SYLLABLE PU
  		0xD494 == code || // Lo       HANGUL SYLLABLE PWEO
  		0xD4B0 == code || // Lo       HANGUL SYLLABLE PWE
  		0xD4CC == code || // Lo       HANGUL SYLLABLE PWI
  		0xD4E8 == code || // Lo       HANGUL SYLLABLE PYU
  		0xD504 == code || // Lo       HANGUL SYLLABLE PEU
  		0xD520 == code || // Lo       HANGUL SYLLABLE PYI
  		0xD53C == code || // Lo       HANGUL SYLLABLE PI
  		0xD558 == code || // Lo       HANGUL SYLLABLE HA
  		0xD574 == code || // Lo       HANGUL SYLLABLE HAE
  		0xD590 == code || // Lo       HANGUL SYLLABLE HYA
  		0xD5AC == code || // Lo       HANGUL SYLLABLE HYAE
  		0xD5C8 == code || // Lo       HANGUL SYLLABLE HEO
  		0xD5E4 == code || // Lo       HANGUL SYLLABLE HE
  		0xD600 == code || // Lo       HANGUL SYLLABLE HYEO
  		0xD61C == code || // Lo       HANGUL SYLLABLE HYE
  		0xD638 == code || // Lo       HANGUL SYLLABLE HO
  		0xD654 == code || // Lo       HANGUL SYLLABLE HWA
  		0xD670 == code || // Lo       HANGUL SYLLABLE HWAE
  		0xD68C == code || // Lo       HANGUL SYLLABLE HOE
  		0xD6A8 == code || // Lo       HANGUL SYLLABLE HYO
  		0xD6C4 == code || // Lo       HANGUL SYLLABLE HU
  		0xD6E0 == code || // Lo       HANGUL SYLLABLE HWEO
  		0xD6FC == code || // Lo       HANGUL SYLLABLE HWE
  		0xD718 == code || // Lo       HANGUL SYLLABLE HWI
  		0xD734 == code || // Lo       HANGUL SYLLABLE HYU
  		0xD750 == code || // Lo       HANGUL SYLLABLE HEU
  		0xD76C == code || // Lo       HANGUL SYLLABLE HYI
  		0xD788 == code // Lo       HANGUL SYLLABLE HI
  		){
  			return LV;
  		}

  		if(
  		(0xAC01 <= code && code <= 0xAC1B) || // Lo  [27] HANGUL SYLLABLE GAG..HANGUL SYLLABLE GAH
  		(0xAC1D <= code && code <= 0xAC37) || // Lo  [27] HANGUL SYLLABLE GAEG..HANGUL SYLLABLE GAEH
  		(0xAC39 <= code && code <= 0xAC53) || // Lo  [27] HANGUL SYLLABLE GYAG..HANGUL SYLLABLE GYAH
  		(0xAC55 <= code && code <= 0xAC6F) || // Lo  [27] HANGUL SYLLABLE GYAEG..HANGUL SYLLABLE GYAEH
  		(0xAC71 <= code && code <= 0xAC8B) || // Lo  [27] HANGUL SYLLABLE GEOG..HANGUL SYLLABLE GEOH
  		(0xAC8D <= code && code <= 0xACA7) || // Lo  [27] HANGUL SYLLABLE GEG..HANGUL SYLLABLE GEH
  		(0xACA9 <= code && code <= 0xACC3) || // Lo  [27] HANGUL SYLLABLE GYEOG..HANGUL SYLLABLE GYEOH
  		(0xACC5 <= code && code <= 0xACDF) || // Lo  [27] HANGUL SYLLABLE GYEG..HANGUL SYLLABLE GYEH
  		(0xACE1 <= code && code <= 0xACFB) || // Lo  [27] HANGUL SYLLABLE GOG..HANGUL SYLLABLE GOH
  		(0xACFD <= code && code <= 0xAD17) || // Lo  [27] HANGUL SYLLABLE GWAG..HANGUL SYLLABLE GWAH
  		(0xAD19 <= code && code <= 0xAD33) || // Lo  [27] HANGUL SYLLABLE GWAEG..HANGUL SYLLABLE GWAEH
  		(0xAD35 <= code && code <= 0xAD4F) || // Lo  [27] HANGUL SYLLABLE GOEG..HANGUL SYLLABLE GOEH
  		(0xAD51 <= code && code <= 0xAD6B) || // Lo  [27] HANGUL SYLLABLE GYOG..HANGUL SYLLABLE GYOH
  		(0xAD6D <= code && code <= 0xAD87) || // Lo  [27] HANGUL SYLLABLE GUG..HANGUL SYLLABLE GUH
  		(0xAD89 <= code && code <= 0xADA3) || // Lo  [27] HANGUL SYLLABLE GWEOG..HANGUL SYLLABLE GWEOH
  		(0xADA5 <= code && code <= 0xADBF) || // Lo  [27] HANGUL SYLLABLE GWEG..HANGUL SYLLABLE GWEH
  		(0xADC1 <= code && code <= 0xADDB) || // Lo  [27] HANGUL SYLLABLE GWIG..HANGUL SYLLABLE GWIH
  		(0xADDD <= code && code <= 0xADF7) || // Lo  [27] HANGUL SYLLABLE GYUG..HANGUL SYLLABLE GYUH
  		(0xADF9 <= code && code <= 0xAE13) || // Lo  [27] HANGUL SYLLABLE GEUG..HANGUL SYLLABLE GEUH
  		(0xAE15 <= code && code <= 0xAE2F) || // Lo  [27] HANGUL SYLLABLE GYIG..HANGUL SYLLABLE GYIH
  		(0xAE31 <= code && code <= 0xAE4B) || // Lo  [27] HANGUL SYLLABLE GIG..HANGUL SYLLABLE GIH
  		(0xAE4D <= code && code <= 0xAE67) || // Lo  [27] HANGUL SYLLABLE GGAG..HANGUL SYLLABLE GGAH
  		(0xAE69 <= code && code <= 0xAE83) || // Lo  [27] HANGUL SYLLABLE GGAEG..HANGUL SYLLABLE GGAEH
  		(0xAE85 <= code && code <= 0xAE9F) || // Lo  [27] HANGUL SYLLABLE GGYAG..HANGUL SYLLABLE GGYAH
  		(0xAEA1 <= code && code <= 0xAEBB) || // Lo  [27] HANGUL SYLLABLE GGYAEG..HANGUL SYLLABLE GGYAEH
  		(0xAEBD <= code && code <= 0xAED7) || // Lo  [27] HANGUL SYLLABLE GGEOG..HANGUL SYLLABLE GGEOH
  		(0xAED9 <= code && code <= 0xAEF3) || // Lo  [27] HANGUL SYLLABLE GGEG..HANGUL SYLLABLE GGEH
  		(0xAEF5 <= code && code <= 0xAF0F) || // Lo  [27] HANGUL SYLLABLE GGYEOG..HANGUL SYLLABLE GGYEOH
  		(0xAF11 <= code && code <= 0xAF2B) || // Lo  [27] HANGUL SYLLABLE GGYEG..HANGUL SYLLABLE GGYEH
  		(0xAF2D <= code && code <= 0xAF47) || // Lo  [27] HANGUL SYLLABLE GGOG..HANGUL SYLLABLE GGOH
  		(0xAF49 <= code && code <= 0xAF63) || // Lo  [27] HANGUL SYLLABLE GGWAG..HANGUL SYLLABLE GGWAH
  		(0xAF65 <= code && code <= 0xAF7F) || // Lo  [27] HANGUL SYLLABLE GGWAEG..HANGUL SYLLABLE GGWAEH
  		(0xAF81 <= code && code <= 0xAF9B) || // Lo  [27] HANGUL SYLLABLE GGOEG..HANGUL SYLLABLE GGOEH
  		(0xAF9D <= code && code <= 0xAFB7) || // Lo  [27] HANGUL SYLLABLE GGYOG..HANGUL SYLLABLE GGYOH
  		(0xAFB9 <= code && code <= 0xAFD3) || // Lo  [27] HANGUL SYLLABLE GGUG..HANGUL SYLLABLE GGUH
  		(0xAFD5 <= code && code <= 0xAFEF) || // Lo  [27] HANGUL SYLLABLE GGWEOG..HANGUL SYLLABLE GGWEOH
  		(0xAFF1 <= code && code <= 0xB00B) || // Lo  [27] HANGUL SYLLABLE GGWEG..HANGUL SYLLABLE GGWEH
  		(0xB00D <= code && code <= 0xB027) || // Lo  [27] HANGUL SYLLABLE GGWIG..HANGUL SYLLABLE GGWIH
  		(0xB029 <= code && code <= 0xB043) || // Lo  [27] HANGUL SYLLABLE GGYUG..HANGUL SYLLABLE GGYUH
  		(0xB045 <= code && code <= 0xB05F) || // Lo  [27] HANGUL SYLLABLE GGEUG..HANGUL SYLLABLE GGEUH
  		(0xB061 <= code && code <= 0xB07B) || // Lo  [27] HANGUL SYLLABLE GGYIG..HANGUL SYLLABLE GGYIH
  		(0xB07D <= code && code <= 0xB097) || // Lo  [27] HANGUL SYLLABLE GGIG..HANGUL SYLLABLE GGIH
  		(0xB099 <= code && code <= 0xB0B3) || // Lo  [27] HANGUL SYLLABLE NAG..HANGUL SYLLABLE NAH
  		(0xB0B5 <= code && code <= 0xB0CF) || // Lo  [27] HANGUL SYLLABLE NAEG..HANGUL SYLLABLE NAEH
  		(0xB0D1 <= code && code <= 0xB0EB) || // Lo  [27] HANGUL SYLLABLE NYAG..HANGUL SYLLABLE NYAH
  		(0xB0ED <= code && code <= 0xB107) || // Lo  [27] HANGUL SYLLABLE NYAEG..HANGUL SYLLABLE NYAEH
  		(0xB109 <= code && code <= 0xB123) || // Lo  [27] HANGUL SYLLABLE NEOG..HANGUL SYLLABLE NEOH
  		(0xB125 <= code && code <= 0xB13F) || // Lo  [27] HANGUL SYLLABLE NEG..HANGUL SYLLABLE NEH
  		(0xB141 <= code && code <= 0xB15B) || // Lo  [27] HANGUL SYLLABLE NYEOG..HANGUL SYLLABLE NYEOH
  		(0xB15D <= code && code <= 0xB177) || // Lo  [27] HANGUL SYLLABLE NYEG..HANGUL SYLLABLE NYEH
  		(0xB179 <= code && code <= 0xB193) || // Lo  [27] HANGUL SYLLABLE NOG..HANGUL SYLLABLE NOH
  		(0xB195 <= code && code <= 0xB1AF) || // Lo  [27] HANGUL SYLLABLE NWAG..HANGUL SYLLABLE NWAH
  		(0xB1B1 <= code && code <= 0xB1CB) || // Lo  [27] HANGUL SYLLABLE NWAEG..HANGUL SYLLABLE NWAEH
  		(0xB1CD <= code && code <= 0xB1E7) || // Lo  [27] HANGUL SYLLABLE NOEG..HANGUL SYLLABLE NOEH
  		(0xB1E9 <= code && code <= 0xB203) || // Lo  [27] HANGUL SYLLABLE NYOG..HANGUL SYLLABLE NYOH
  		(0xB205 <= code && code <= 0xB21F) || // Lo  [27] HANGUL SYLLABLE NUG..HANGUL SYLLABLE NUH
  		(0xB221 <= code && code <= 0xB23B) || // Lo  [27] HANGUL SYLLABLE NWEOG..HANGUL SYLLABLE NWEOH
  		(0xB23D <= code && code <= 0xB257) || // Lo  [27] HANGUL SYLLABLE NWEG..HANGUL SYLLABLE NWEH
  		(0xB259 <= code && code <= 0xB273) || // Lo  [27] HANGUL SYLLABLE NWIG..HANGUL SYLLABLE NWIH
  		(0xB275 <= code && code <= 0xB28F) || // Lo  [27] HANGUL SYLLABLE NYUG..HANGUL SYLLABLE NYUH
  		(0xB291 <= code && code <= 0xB2AB) || // Lo  [27] HANGUL SYLLABLE NEUG..HANGUL SYLLABLE NEUH
  		(0xB2AD <= code && code <= 0xB2C7) || // Lo  [27] HANGUL SYLLABLE NYIG..HANGUL SYLLABLE NYIH
  		(0xB2C9 <= code && code <= 0xB2E3) || // Lo  [27] HANGUL SYLLABLE NIG..HANGUL SYLLABLE NIH
  		(0xB2E5 <= code && code <= 0xB2FF) || // Lo  [27] HANGUL SYLLABLE DAG..HANGUL SYLLABLE DAH
  		(0xB301 <= code && code <= 0xB31B) || // Lo  [27] HANGUL SYLLABLE DAEG..HANGUL SYLLABLE DAEH
  		(0xB31D <= code && code <= 0xB337) || // Lo  [27] HANGUL SYLLABLE DYAG..HANGUL SYLLABLE DYAH
  		(0xB339 <= code && code <= 0xB353) || // Lo  [27] HANGUL SYLLABLE DYAEG..HANGUL SYLLABLE DYAEH
  		(0xB355 <= code && code <= 0xB36F) || // Lo  [27] HANGUL SYLLABLE DEOG..HANGUL SYLLABLE DEOH
  		(0xB371 <= code && code <= 0xB38B) || // Lo  [27] HANGUL SYLLABLE DEG..HANGUL SYLLABLE DEH
  		(0xB38D <= code && code <= 0xB3A7) || // Lo  [27] HANGUL SYLLABLE DYEOG..HANGUL SYLLABLE DYEOH
  		(0xB3A9 <= code && code <= 0xB3C3) || // Lo  [27] HANGUL SYLLABLE DYEG..HANGUL SYLLABLE DYEH
  		(0xB3C5 <= code && code <= 0xB3DF) || // Lo  [27] HANGUL SYLLABLE DOG..HANGUL SYLLABLE DOH
  		(0xB3E1 <= code && code <= 0xB3FB) || // Lo  [27] HANGUL SYLLABLE DWAG..HANGUL SYLLABLE DWAH
  		(0xB3FD <= code && code <= 0xB417) || // Lo  [27] HANGUL SYLLABLE DWAEG..HANGUL SYLLABLE DWAEH
  		(0xB419 <= code && code <= 0xB433) || // Lo  [27] HANGUL SYLLABLE DOEG..HANGUL SYLLABLE DOEH
  		(0xB435 <= code && code <= 0xB44F) || // Lo  [27] HANGUL SYLLABLE DYOG..HANGUL SYLLABLE DYOH
  		(0xB451 <= code && code <= 0xB46B) || // Lo  [27] HANGUL SYLLABLE DUG..HANGUL SYLLABLE DUH
  		(0xB46D <= code && code <= 0xB487) || // Lo  [27] HANGUL SYLLABLE DWEOG..HANGUL SYLLABLE DWEOH
  		(0xB489 <= code && code <= 0xB4A3) || // Lo  [27] HANGUL SYLLABLE DWEG..HANGUL SYLLABLE DWEH
  		(0xB4A5 <= code && code <= 0xB4BF) || // Lo  [27] HANGUL SYLLABLE DWIG..HANGUL SYLLABLE DWIH
  		(0xB4C1 <= code && code <= 0xB4DB) || // Lo  [27] HANGUL SYLLABLE DYUG..HANGUL SYLLABLE DYUH
  		(0xB4DD <= code && code <= 0xB4F7) || // Lo  [27] HANGUL SYLLABLE DEUG..HANGUL SYLLABLE DEUH
  		(0xB4F9 <= code && code <= 0xB513) || // Lo  [27] HANGUL SYLLABLE DYIG..HANGUL SYLLABLE DYIH
  		(0xB515 <= code && code <= 0xB52F) || // Lo  [27] HANGUL SYLLABLE DIG..HANGUL SYLLABLE DIH
  		(0xB531 <= code && code <= 0xB54B) || // Lo  [27] HANGUL SYLLABLE DDAG..HANGUL SYLLABLE DDAH
  		(0xB54D <= code && code <= 0xB567) || // Lo  [27] HANGUL SYLLABLE DDAEG..HANGUL SYLLABLE DDAEH
  		(0xB569 <= code && code <= 0xB583) || // Lo  [27] HANGUL SYLLABLE DDYAG..HANGUL SYLLABLE DDYAH
  		(0xB585 <= code && code <= 0xB59F) || // Lo  [27] HANGUL SYLLABLE DDYAEG..HANGUL SYLLABLE DDYAEH
  		(0xB5A1 <= code && code <= 0xB5BB) || // Lo  [27] HANGUL SYLLABLE DDEOG..HANGUL SYLLABLE DDEOH
  		(0xB5BD <= code && code <= 0xB5D7) || // Lo  [27] HANGUL SYLLABLE DDEG..HANGUL SYLLABLE DDEH
  		(0xB5D9 <= code && code <= 0xB5F3) || // Lo  [27] HANGUL SYLLABLE DDYEOG..HANGUL SYLLABLE DDYEOH
  		(0xB5F5 <= code && code <= 0xB60F) || // Lo  [27] HANGUL SYLLABLE DDYEG..HANGUL SYLLABLE DDYEH
  		(0xB611 <= code && code <= 0xB62B) || // Lo  [27] HANGUL SYLLABLE DDOG..HANGUL SYLLABLE DDOH
  		(0xB62D <= code && code <= 0xB647) || // Lo  [27] HANGUL SYLLABLE DDWAG..HANGUL SYLLABLE DDWAH
  		(0xB649 <= code && code <= 0xB663) || // Lo  [27] HANGUL SYLLABLE DDWAEG..HANGUL SYLLABLE DDWAEH
  		(0xB665 <= code && code <= 0xB67F) || // Lo  [27] HANGUL SYLLABLE DDOEG..HANGUL SYLLABLE DDOEH
  		(0xB681 <= code && code <= 0xB69B) || // Lo  [27] HANGUL SYLLABLE DDYOG..HANGUL SYLLABLE DDYOH
  		(0xB69D <= code && code <= 0xB6B7) || // Lo  [27] HANGUL SYLLABLE DDUG..HANGUL SYLLABLE DDUH
  		(0xB6B9 <= code && code <= 0xB6D3) || // Lo  [27] HANGUL SYLLABLE DDWEOG..HANGUL SYLLABLE DDWEOH
  		(0xB6D5 <= code && code <= 0xB6EF) || // Lo  [27] HANGUL SYLLABLE DDWEG..HANGUL SYLLABLE DDWEH
  		(0xB6F1 <= code && code <= 0xB70B) || // Lo  [27] HANGUL SYLLABLE DDWIG..HANGUL SYLLABLE DDWIH
  		(0xB70D <= code && code <= 0xB727) || // Lo  [27] HANGUL SYLLABLE DDYUG..HANGUL SYLLABLE DDYUH
  		(0xB729 <= code && code <= 0xB743) || // Lo  [27] HANGUL SYLLABLE DDEUG..HANGUL SYLLABLE DDEUH
  		(0xB745 <= code && code <= 0xB75F) || // Lo  [27] HANGUL SYLLABLE DDYIG..HANGUL SYLLABLE DDYIH
  		(0xB761 <= code && code <= 0xB77B) || // Lo  [27] HANGUL SYLLABLE DDIG..HANGUL SYLLABLE DDIH
  		(0xB77D <= code && code <= 0xB797) || // Lo  [27] HANGUL SYLLABLE RAG..HANGUL SYLLABLE RAH
  		(0xB799 <= code && code <= 0xB7B3) || // Lo  [27] HANGUL SYLLABLE RAEG..HANGUL SYLLABLE RAEH
  		(0xB7B5 <= code && code <= 0xB7CF) || // Lo  [27] HANGUL SYLLABLE RYAG..HANGUL SYLLABLE RYAH
  		(0xB7D1 <= code && code <= 0xB7EB) || // Lo  [27] HANGUL SYLLABLE RYAEG..HANGUL SYLLABLE RYAEH
  		(0xB7ED <= code && code <= 0xB807) || // Lo  [27] HANGUL SYLLABLE REOG..HANGUL SYLLABLE REOH
  		(0xB809 <= code && code <= 0xB823) || // Lo  [27] HANGUL SYLLABLE REG..HANGUL SYLLABLE REH
  		(0xB825 <= code && code <= 0xB83F) || // Lo  [27] HANGUL SYLLABLE RYEOG..HANGUL SYLLABLE RYEOH
  		(0xB841 <= code && code <= 0xB85B) || // Lo  [27] HANGUL SYLLABLE RYEG..HANGUL SYLLABLE RYEH
  		(0xB85D <= code && code <= 0xB877) || // Lo  [27] HANGUL SYLLABLE ROG..HANGUL SYLLABLE ROH
  		(0xB879 <= code && code <= 0xB893) || // Lo  [27] HANGUL SYLLABLE RWAG..HANGUL SYLLABLE RWAH
  		(0xB895 <= code && code <= 0xB8AF) || // Lo  [27] HANGUL SYLLABLE RWAEG..HANGUL SYLLABLE RWAEH
  		(0xB8B1 <= code && code <= 0xB8CB) || // Lo  [27] HANGUL SYLLABLE ROEG..HANGUL SYLLABLE ROEH
  		(0xB8CD <= code && code <= 0xB8E7) || // Lo  [27] HANGUL SYLLABLE RYOG..HANGUL SYLLABLE RYOH
  		(0xB8E9 <= code && code <= 0xB903) || // Lo  [27] HANGUL SYLLABLE RUG..HANGUL SYLLABLE RUH
  		(0xB905 <= code && code <= 0xB91F) || // Lo  [27] HANGUL SYLLABLE RWEOG..HANGUL SYLLABLE RWEOH
  		(0xB921 <= code && code <= 0xB93B) || // Lo  [27] HANGUL SYLLABLE RWEG..HANGUL SYLLABLE RWEH
  		(0xB93D <= code && code <= 0xB957) || // Lo  [27] HANGUL SYLLABLE RWIG..HANGUL SYLLABLE RWIH
  		(0xB959 <= code && code <= 0xB973) || // Lo  [27] HANGUL SYLLABLE RYUG..HANGUL SYLLABLE RYUH
  		(0xB975 <= code && code <= 0xB98F) || // Lo  [27] HANGUL SYLLABLE REUG..HANGUL SYLLABLE REUH
  		(0xB991 <= code && code <= 0xB9AB) || // Lo  [27] HANGUL SYLLABLE RYIG..HANGUL SYLLABLE RYIH
  		(0xB9AD <= code && code <= 0xB9C7) || // Lo  [27] HANGUL SYLLABLE RIG..HANGUL SYLLABLE RIH
  		(0xB9C9 <= code && code <= 0xB9E3) || // Lo  [27] HANGUL SYLLABLE MAG..HANGUL SYLLABLE MAH
  		(0xB9E5 <= code && code <= 0xB9FF) || // Lo  [27] HANGUL SYLLABLE MAEG..HANGUL SYLLABLE MAEH
  		(0xBA01 <= code && code <= 0xBA1B) || // Lo  [27] HANGUL SYLLABLE MYAG..HANGUL SYLLABLE MYAH
  		(0xBA1D <= code && code <= 0xBA37) || // Lo  [27] HANGUL SYLLABLE MYAEG..HANGUL SYLLABLE MYAEH
  		(0xBA39 <= code && code <= 0xBA53) || // Lo  [27] HANGUL SYLLABLE MEOG..HANGUL SYLLABLE MEOH
  		(0xBA55 <= code && code <= 0xBA6F) || // Lo  [27] HANGUL SYLLABLE MEG..HANGUL SYLLABLE MEH
  		(0xBA71 <= code && code <= 0xBA8B) || // Lo  [27] HANGUL SYLLABLE MYEOG..HANGUL SYLLABLE MYEOH
  		(0xBA8D <= code && code <= 0xBAA7) || // Lo  [27] HANGUL SYLLABLE MYEG..HANGUL SYLLABLE MYEH
  		(0xBAA9 <= code && code <= 0xBAC3) || // Lo  [27] HANGUL SYLLABLE MOG..HANGUL SYLLABLE MOH
  		(0xBAC5 <= code && code <= 0xBADF) || // Lo  [27] HANGUL SYLLABLE MWAG..HANGUL SYLLABLE MWAH
  		(0xBAE1 <= code && code <= 0xBAFB) || // Lo  [27] HANGUL SYLLABLE MWAEG..HANGUL SYLLABLE MWAEH
  		(0xBAFD <= code && code <= 0xBB17) || // Lo  [27] HANGUL SYLLABLE MOEG..HANGUL SYLLABLE MOEH
  		(0xBB19 <= code && code <= 0xBB33) || // Lo  [27] HANGUL SYLLABLE MYOG..HANGUL SYLLABLE MYOH
  		(0xBB35 <= code && code <= 0xBB4F) || // Lo  [27] HANGUL SYLLABLE MUG..HANGUL SYLLABLE MUH
  		(0xBB51 <= code && code <= 0xBB6B) || // Lo  [27] HANGUL SYLLABLE MWEOG..HANGUL SYLLABLE MWEOH
  		(0xBB6D <= code && code <= 0xBB87) || // Lo  [27] HANGUL SYLLABLE MWEG..HANGUL SYLLABLE MWEH
  		(0xBB89 <= code && code <= 0xBBA3) || // Lo  [27] HANGUL SYLLABLE MWIG..HANGUL SYLLABLE MWIH
  		(0xBBA5 <= code && code <= 0xBBBF) || // Lo  [27] HANGUL SYLLABLE MYUG..HANGUL SYLLABLE MYUH
  		(0xBBC1 <= code && code <= 0xBBDB) || // Lo  [27] HANGUL SYLLABLE MEUG..HANGUL SYLLABLE MEUH
  		(0xBBDD <= code && code <= 0xBBF7) || // Lo  [27] HANGUL SYLLABLE MYIG..HANGUL SYLLABLE MYIH
  		(0xBBF9 <= code && code <= 0xBC13) || // Lo  [27] HANGUL SYLLABLE MIG..HANGUL SYLLABLE MIH
  		(0xBC15 <= code && code <= 0xBC2F) || // Lo  [27] HANGUL SYLLABLE BAG..HANGUL SYLLABLE BAH
  		(0xBC31 <= code && code <= 0xBC4B) || // Lo  [27] HANGUL SYLLABLE BAEG..HANGUL SYLLABLE BAEH
  		(0xBC4D <= code && code <= 0xBC67) || // Lo  [27] HANGUL SYLLABLE BYAG..HANGUL SYLLABLE BYAH
  		(0xBC69 <= code && code <= 0xBC83) || // Lo  [27] HANGUL SYLLABLE BYAEG..HANGUL SYLLABLE BYAEH
  		(0xBC85 <= code && code <= 0xBC9F) || // Lo  [27] HANGUL SYLLABLE BEOG..HANGUL SYLLABLE BEOH
  		(0xBCA1 <= code && code <= 0xBCBB) || // Lo  [27] HANGUL SYLLABLE BEG..HANGUL SYLLABLE BEH
  		(0xBCBD <= code && code <= 0xBCD7) || // Lo  [27] HANGUL SYLLABLE BYEOG..HANGUL SYLLABLE BYEOH
  		(0xBCD9 <= code && code <= 0xBCF3) || // Lo  [27] HANGUL SYLLABLE BYEG..HANGUL SYLLABLE BYEH
  		(0xBCF5 <= code && code <= 0xBD0F) || // Lo  [27] HANGUL SYLLABLE BOG..HANGUL SYLLABLE BOH
  		(0xBD11 <= code && code <= 0xBD2B) || // Lo  [27] HANGUL SYLLABLE BWAG..HANGUL SYLLABLE BWAH
  		(0xBD2D <= code && code <= 0xBD47) || // Lo  [27] HANGUL SYLLABLE BWAEG..HANGUL SYLLABLE BWAEH
  		(0xBD49 <= code && code <= 0xBD63) || // Lo  [27] HANGUL SYLLABLE BOEG..HANGUL SYLLABLE BOEH
  		(0xBD65 <= code && code <= 0xBD7F) || // Lo  [27] HANGUL SYLLABLE BYOG..HANGUL SYLLABLE BYOH
  		(0xBD81 <= code && code <= 0xBD9B) || // Lo  [27] HANGUL SYLLABLE BUG..HANGUL SYLLABLE BUH
  		(0xBD9D <= code && code <= 0xBDB7) || // Lo  [27] HANGUL SYLLABLE BWEOG..HANGUL SYLLABLE BWEOH
  		(0xBDB9 <= code && code <= 0xBDD3) || // Lo  [27] HANGUL SYLLABLE BWEG..HANGUL SYLLABLE BWEH
  		(0xBDD5 <= code && code <= 0xBDEF) || // Lo  [27] HANGUL SYLLABLE BWIG..HANGUL SYLLABLE BWIH
  		(0xBDF1 <= code && code <= 0xBE0B) || // Lo  [27] HANGUL SYLLABLE BYUG..HANGUL SYLLABLE BYUH
  		(0xBE0D <= code && code <= 0xBE27) || // Lo  [27] HANGUL SYLLABLE BEUG..HANGUL SYLLABLE BEUH
  		(0xBE29 <= code && code <= 0xBE43) || // Lo  [27] HANGUL SYLLABLE BYIG..HANGUL SYLLABLE BYIH
  		(0xBE45 <= code && code <= 0xBE5F) || // Lo  [27] HANGUL SYLLABLE BIG..HANGUL SYLLABLE BIH
  		(0xBE61 <= code && code <= 0xBE7B) || // Lo  [27] HANGUL SYLLABLE BBAG..HANGUL SYLLABLE BBAH
  		(0xBE7D <= code && code <= 0xBE97) || // Lo  [27] HANGUL SYLLABLE BBAEG..HANGUL SYLLABLE BBAEH
  		(0xBE99 <= code && code <= 0xBEB3) || // Lo  [27] HANGUL SYLLABLE BBYAG..HANGUL SYLLABLE BBYAH
  		(0xBEB5 <= code && code <= 0xBECF) || // Lo  [27] HANGUL SYLLABLE BBYAEG..HANGUL SYLLABLE BBYAEH
  		(0xBED1 <= code && code <= 0xBEEB) || // Lo  [27] HANGUL SYLLABLE BBEOG..HANGUL SYLLABLE BBEOH
  		(0xBEED <= code && code <= 0xBF07) || // Lo  [27] HANGUL SYLLABLE BBEG..HANGUL SYLLABLE BBEH
  		(0xBF09 <= code && code <= 0xBF23) || // Lo  [27] HANGUL SYLLABLE BBYEOG..HANGUL SYLLABLE BBYEOH
  		(0xBF25 <= code && code <= 0xBF3F) || // Lo  [27] HANGUL SYLLABLE BBYEG..HANGUL SYLLABLE BBYEH
  		(0xBF41 <= code && code <= 0xBF5B) || // Lo  [27] HANGUL SYLLABLE BBOG..HANGUL SYLLABLE BBOH
  		(0xBF5D <= code && code <= 0xBF77) || // Lo  [27] HANGUL SYLLABLE BBWAG..HANGUL SYLLABLE BBWAH
  		(0xBF79 <= code && code <= 0xBF93) || // Lo  [27] HANGUL SYLLABLE BBWAEG..HANGUL SYLLABLE BBWAEH
  		(0xBF95 <= code && code <= 0xBFAF) || // Lo  [27] HANGUL SYLLABLE BBOEG..HANGUL SYLLABLE BBOEH
  		(0xBFB1 <= code && code <= 0xBFCB) || // Lo  [27] HANGUL SYLLABLE BBYOG..HANGUL SYLLABLE BBYOH
  		(0xBFCD <= code && code <= 0xBFE7) || // Lo  [27] HANGUL SYLLABLE BBUG..HANGUL SYLLABLE BBUH
  		(0xBFE9 <= code && code <= 0xC003) || // Lo  [27] HANGUL SYLLABLE BBWEOG..HANGUL SYLLABLE BBWEOH
  		(0xC005 <= code && code <= 0xC01F) || // Lo  [27] HANGUL SYLLABLE BBWEG..HANGUL SYLLABLE BBWEH
  		(0xC021 <= code && code <= 0xC03B) || // Lo  [27] HANGUL SYLLABLE BBWIG..HANGUL SYLLABLE BBWIH
  		(0xC03D <= code && code <= 0xC057) || // Lo  [27] HANGUL SYLLABLE BBYUG..HANGUL SYLLABLE BBYUH
  		(0xC059 <= code && code <= 0xC073) || // Lo  [27] HANGUL SYLLABLE BBEUG..HANGUL SYLLABLE BBEUH
  		(0xC075 <= code && code <= 0xC08F) || // Lo  [27] HANGUL SYLLABLE BBYIG..HANGUL SYLLABLE BBYIH
  		(0xC091 <= code && code <= 0xC0AB) || // Lo  [27] HANGUL SYLLABLE BBIG..HANGUL SYLLABLE BBIH
  		(0xC0AD <= code && code <= 0xC0C7) || // Lo  [27] HANGUL SYLLABLE SAG..HANGUL SYLLABLE SAH
  		(0xC0C9 <= code && code <= 0xC0E3) || // Lo  [27] HANGUL SYLLABLE SAEG..HANGUL SYLLABLE SAEH
  		(0xC0E5 <= code && code <= 0xC0FF) || // Lo  [27] HANGUL SYLLABLE SYAG..HANGUL SYLLABLE SYAH
  		(0xC101 <= code && code <= 0xC11B) || // Lo  [27] HANGUL SYLLABLE SYAEG..HANGUL SYLLABLE SYAEH
  		(0xC11D <= code && code <= 0xC137) || // Lo  [27] HANGUL SYLLABLE SEOG..HANGUL SYLLABLE SEOH
  		(0xC139 <= code && code <= 0xC153) || // Lo  [27] HANGUL SYLLABLE SEG..HANGUL SYLLABLE SEH
  		(0xC155 <= code && code <= 0xC16F) || // Lo  [27] HANGUL SYLLABLE SYEOG..HANGUL SYLLABLE SYEOH
  		(0xC171 <= code && code <= 0xC18B) || // Lo  [27] HANGUL SYLLABLE SYEG..HANGUL SYLLABLE SYEH
  		(0xC18D <= code && code <= 0xC1A7) || // Lo  [27] HANGUL SYLLABLE SOG..HANGUL SYLLABLE SOH
  		(0xC1A9 <= code && code <= 0xC1C3) || // Lo  [27] HANGUL SYLLABLE SWAG..HANGUL SYLLABLE SWAH
  		(0xC1C5 <= code && code <= 0xC1DF) || // Lo  [27] HANGUL SYLLABLE SWAEG..HANGUL SYLLABLE SWAEH
  		(0xC1E1 <= code && code <= 0xC1FB) || // Lo  [27] HANGUL SYLLABLE SOEG..HANGUL SYLLABLE SOEH
  		(0xC1FD <= code && code <= 0xC217) || // Lo  [27] HANGUL SYLLABLE SYOG..HANGUL SYLLABLE SYOH
  		(0xC219 <= code && code <= 0xC233) || // Lo  [27] HANGUL SYLLABLE SUG..HANGUL SYLLABLE SUH
  		(0xC235 <= code && code <= 0xC24F) || // Lo  [27] HANGUL SYLLABLE SWEOG..HANGUL SYLLABLE SWEOH
  		(0xC251 <= code && code <= 0xC26B) || // Lo  [27] HANGUL SYLLABLE SWEG..HANGUL SYLLABLE SWEH
  		(0xC26D <= code && code <= 0xC287) || // Lo  [27] HANGUL SYLLABLE SWIG..HANGUL SYLLABLE SWIH
  		(0xC289 <= code && code <= 0xC2A3) || // Lo  [27] HANGUL SYLLABLE SYUG..HANGUL SYLLABLE SYUH
  		(0xC2A5 <= code && code <= 0xC2BF) || // Lo  [27] HANGUL SYLLABLE SEUG..HANGUL SYLLABLE SEUH
  		(0xC2C1 <= code && code <= 0xC2DB) || // Lo  [27] HANGUL SYLLABLE SYIG..HANGUL SYLLABLE SYIH
  		(0xC2DD <= code && code <= 0xC2F7) || // Lo  [27] HANGUL SYLLABLE SIG..HANGUL SYLLABLE SIH
  		(0xC2F9 <= code && code <= 0xC313) || // Lo  [27] HANGUL SYLLABLE SSAG..HANGUL SYLLABLE SSAH
  		(0xC315 <= code && code <= 0xC32F) || // Lo  [27] HANGUL SYLLABLE SSAEG..HANGUL SYLLABLE SSAEH
  		(0xC331 <= code && code <= 0xC34B) || // Lo  [27] HANGUL SYLLABLE SSYAG..HANGUL SYLLABLE SSYAH
  		(0xC34D <= code && code <= 0xC367) || // Lo  [27] HANGUL SYLLABLE SSYAEG..HANGUL SYLLABLE SSYAEH
  		(0xC369 <= code && code <= 0xC383) || // Lo  [27] HANGUL SYLLABLE SSEOG..HANGUL SYLLABLE SSEOH
  		(0xC385 <= code && code <= 0xC39F) || // Lo  [27] HANGUL SYLLABLE SSEG..HANGUL SYLLABLE SSEH
  		(0xC3A1 <= code && code <= 0xC3BB) || // Lo  [27] HANGUL SYLLABLE SSYEOG..HANGUL SYLLABLE SSYEOH
  		(0xC3BD <= code && code <= 0xC3D7) || // Lo  [27] HANGUL SYLLABLE SSYEG..HANGUL SYLLABLE SSYEH
  		(0xC3D9 <= code && code <= 0xC3F3) || // Lo  [27] HANGUL SYLLABLE SSOG..HANGUL SYLLABLE SSOH
  		(0xC3F5 <= code && code <= 0xC40F) || // Lo  [27] HANGUL SYLLABLE SSWAG..HANGUL SYLLABLE SSWAH
  		(0xC411 <= code && code <= 0xC42B) || // Lo  [27] HANGUL SYLLABLE SSWAEG..HANGUL SYLLABLE SSWAEH
  		(0xC42D <= code && code <= 0xC447) || // Lo  [27] HANGUL SYLLABLE SSOEG..HANGUL SYLLABLE SSOEH
  		(0xC449 <= code && code <= 0xC463) || // Lo  [27] HANGUL SYLLABLE SSYOG..HANGUL SYLLABLE SSYOH
  		(0xC465 <= code && code <= 0xC47F) || // Lo  [27] HANGUL SYLLABLE SSUG..HANGUL SYLLABLE SSUH
  		(0xC481 <= code && code <= 0xC49B) || // Lo  [27] HANGUL SYLLABLE SSWEOG..HANGUL SYLLABLE SSWEOH
  		(0xC49D <= code && code <= 0xC4B7) || // Lo  [27] HANGUL SYLLABLE SSWEG..HANGUL SYLLABLE SSWEH
  		(0xC4B9 <= code && code <= 0xC4D3) || // Lo  [27] HANGUL SYLLABLE SSWIG..HANGUL SYLLABLE SSWIH
  		(0xC4D5 <= code && code <= 0xC4EF) || // Lo  [27] HANGUL SYLLABLE SSYUG..HANGUL SYLLABLE SSYUH
  		(0xC4F1 <= code && code <= 0xC50B) || // Lo  [27] HANGUL SYLLABLE SSEUG..HANGUL SYLLABLE SSEUH
  		(0xC50D <= code && code <= 0xC527) || // Lo  [27] HANGUL SYLLABLE SSYIG..HANGUL SYLLABLE SSYIH
  		(0xC529 <= code && code <= 0xC543) || // Lo  [27] HANGUL SYLLABLE SSIG..HANGUL SYLLABLE SSIH
  		(0xC545 <= code && code <= 0xC55F) || // Lo  [27] HANGUL SYLLABLE AG..HANGUL SYLLABLE AH
  		(0xC561 <= code && code <= 0xC57B) || // Lo  [27] HANGUL SYLLABLE AEG..HANGUL SYLLABLE AEH
  		(0xC57D <= code && code <= 0xC597) || // Lo  [27] HANGUL SYLLABLE YAG..HANGUL SYLLABLE YAH
  		(0xC599 <= code && code <= 0xC5B3) || // Lo  [27] HANGUL SYLLABLE YAEG..HANGUL SYLLABLE YAEH
  		(0xC5B5 <= code && code <= 0xC5CF) || // Lo  [27] HANGUL SYLLABLE EOG..HANGUL SYLLABLE EOH
  		(0xC5D1 <= code && code <= 0xC5EB) || // Lo  [27] HANGUL SYLLABLE EG..HANGUL SYLLABLE EH
  		(0xC5ED <= code && code <= 0xC607) || // Lo  [27] HANGUL SYLLABLE YEOG..HANGUL SYLLABLE YEOH
  		(0xC609 <= code && code <= 0xC623) || // Lo  [27] HANGUL SYLLABLE YEG..HANGUL SYLLABLE YEH
  		(0xC625 <= code && code <= 0xC63F) || // Lo  [27] HANGUL SYLLABLE OG..HANGUL SYLLABLE OH
  		(0xC641 <= code && code <= 0xC65B) || // Lo  [27] HANGUL SYLLABLE WAG..HANGUL SYLLABLE WAH
  		(0xC65D <= code && code <= 0xC677) || // Lo  [27] HANGUL SYLLABLE WAEG..HANGUL SYLLABLE WAEH
  		(0xC679 <= code && code <= 0xC693) || // Lo  [27] HANGUL SYLLABLE OEG..HANGUL SYLLABLE OEH
  		(0xC695 <= code && code <= 0xC6AF) || // Lo  [27] HANGUL SYLLABLE YOG..HANGUL SYLLABLE YOH
  		(0xC6B1 <= code && code <= 0xC6CB) || // Lo  [27] HANGUL SYLLABLE UG..HANGUL SYLLABLE UH
  		(0xC6CD <= code && code <= 0xC6E7) || // Lo  [27] HANGUL SYLLABLE WEOG..HANGUL SYLLABLE WEOH
  		(0xC6E9 <= code && code <= 0xC703) || // Lo  [27] HANGUL SYLLABLE WEG..HANGUL SYLLABLE WEH
  		(0xC705 <= code && code <= 0xC71F) || // Lo  [27] HANGUL SYLLABLE WIG..HANGUL SYLLABLE WIH
  		(0xC721 <= code && code <= 0xC73B) || // Lo  [27] HANGUL SYLLABLE YUG..HANGUL SYLLABLE YUH
  		(0xC73D <= code && code <= 0xC757) || // Lo  [27] HANGUL SYLLABLE EUG..HANGUL SYLLABLE EUH
  		(0xC759 <= code && code <= 0xC773) || // Lo  [27] HANGUL SYLLABLE YIG..HANGUL SYLLABLE YIH
  		(0xC775 <= code && code <= 0xC78F) || // Lo  [27] HANGUL SYLLABLE IG..HANGUL SYLLABLE IH
  		(0xC791 <= code && code <= 0xC7AB) || // Lo  [27] HANGUL SYLLABLE JAG..HANGUL SYLLABLE JAH
  		(0xC7AD <= code && code <= 0xC7C7) || // Lo  [27] HANGUL SYLLABLE JAEG..HANGUL SYLLABLE JAEH
  		(0xC7C9 <= code && code <= 0xC7E3) || // Lo  [27] HANGUL SYLLABLE JYAG..HANGUL SYLLABLE JYAH
  		(0xC7E5 <= code && code <= 0xC7FF) || // Lo  [27] HANGUL SYLLABLE JYAEG..HANGUL SYLLABLE JYAEH
  		(0xC801 <= code && code <= 0xC81B) || // Lo  [27] HANGUL SYLLABLE JEOG..HANGUL SYLLABLE JEOH
  		(0xC81D <= code && code <= 0xC837) || // Lo  [27] HANGUL SYLLABLE JEG..HANGUL SYLLABLE JEH
  		(0xC839 <= code && code <= 0xC853) || // Lo  [27] HANGUL SYLLABLE JYEOG..HANGUL SYLLABLE JYEOH
  		(0xC855 <= code && code <= 0xC86F) || // Lo  [27] HANGUL SYLLABLE JYEG..HANGUL SYLLABLE JYEH
  		(0xC871 <= code && code <= 0xC88B) || // Lo  [27] HANGUL SYLLABLE JOG..HANGUL SYLLABLE JOH
  		(0xC88D <= code && code <= 0xC8A7) || // Lo  [27] HANGUL SYLLABLE JWAG..HANGUL SYLLABLE JWAH
  		(0xC8A9 <= code && code <= 0xC8C3) || // Lo  [27] HANGUL SYLLABLE JWAEG..HANGUL SYLLABLE JWAEH
  		(0xC8C5 <= code && code <= 0xC8DF) || // Lo  [27] HANGUL SYLLABLE JOEG..HANGUL SYLLABLE JOEH
  		(0xC8E1 <= code && code <= 0xC8FB) || // Lo  [27] HANGUL SYLLABLE JYOG..HANGUL SYLLABLE JYOH
  		(0xC8FD <= code && code <= 0xC917) || // Lo  [27] HANGUL SYLLABLE JUG..HANGUL SYLLABLE JUH
  		(0xC919 <= code && code <= 0xC933) || // Lo  [27] HANGUL SYLLABLE JWEOG..HANGUL SYLLABLE JWEOH
  		(0xC935 <= code && code <= 0xC94F) || // Lo  [27] HANGUL SYLLABLE JWEG..HANGUL SYLLABLE JWEH
  		(0xC951 <= code && code <= 0xC96B) || // Lo  [27] HANGUL SYLLABLE JWIG..HANGUL SYLLABLE JWIH
  		(0xC96D <= code && code <= 0xC987) || // Lo  [27] HANGUL SYLLABLE JYUG..HANGUL SYLLABLE JYUH
  		(0xC989 <= code && code <= 0xC9A3) || // Lo  [27] HANGUL SYLLABLE JEUG..HANGUL SYLLABLE JEUH
  		(0xC9A5 <= code && code <= 0xC9BF) || // Lo  [27] HANGUL SYLLABLE JYIG..HANGUL SYLLABLE JYIH
  		(0xC9C1 <= code && code <= 0xC9DB) || // Lo  [27] HANGUL SYLLABLE JIG..HANGUL SYLLABLE JIH
  		(0xC9DD <= code && code <= 0xC9F7) || // Lo  [27] HANGUL SYLLABLE JJAG..HANGUL SYLLABLE JJAH
  		(0xC9F9 <= code && code <= 0xCA13) || // Lo  [27] HANGUL SYLLABLE JJAEG..HANGUL SYLLABLE JJAEH
  		(0xCA15 <= code && code <= 0xCA2F) || // Lo  [27] HANGUL SYLLABLE JJYAG..HANGUL SYLLABLE JJYAH
  		(0xCA31 <= code && code <= 0xCA4B) || // Lo  [27] HANGUL SYLLABLE JJYAEG..HANGUL SYLLABLE JJYAEH
  		(0xCA4D <= code && code <= 0xCA67) || // Lo  [27] HANGUL SYLLABLE JJEOG..HANGUL SYLLABLE JJEOH
  		(0xCA69 <= code && code <= 0xCA83) || // Lo  [27] HANGUL SYLLABLE JJEG..HANGUL SYLLABLE JJEH
  		(0xCA85 <= code && code <= 0xCA9F) || // Lo  [27] HANGUL SYLLABLE JJYEOG..HANGUL SYLLABLE JJYEOH
  		(0xCAA1 <= code && code <= 0xCABB) || // Lo  [27] HANGUL SYLLABLE JJYEG..HANGUL SYLLABLE JJYEH
  		(0xCABD <= code && code <= 0xCAD7) || // Lo  [27] HANGUL SYLLABLE JJOG..HANGUL SYLLABLE JJOH
  		(0xCAD9 <= code && code <= 0xCAF3) || // Lo  [27] HANGUL SYLLABLE JJWAG..HANGUL SYLLABLE JJWAH
  		(0xCAF5 <= code && code <= 0xCB0F) || // Lo  [27] HANGUL SYLLABLE JJWAEG..HANGUL SYLLABLE JJWAEH
  		(0xCB11 <= code && code <= 0xCB2B) || // Lo  [27] HANGUL SYLLABLE JJOEG..HANGUL SYLLABLE JJOEH
  		(0xCB2D <= code && code <= 0xCB47) || // Lo  [27] HANGUL SYLLABLE JJYOG..HANGUL SYLLABLE JJYOH
  		(0xCB49 <= code && code <= 0xCB63) || // Lo  [27] HANGUL SYLLABLE JJUG..HANGUL SYLLABLE JJUH
  		(0xCB65 <= code && code <= 0xCB7F) || // Lo  [27] HANGUL SYLLABLE JJWEOG..HANGUL SYLLABLE JJWEOH
  		(0xCB81 <= code && code <= 0xCB9B) || // Lo  [27] HANGUL SYLLABLE JJWEG..HANGUL SYLLABLE JJWEH
  		(0xCB9D <= code && code <= 0xCBB7) || // Lo  [27] HANGUL SYLLABLE JJWIG..HANGUL SYLLABLE JJWIH
  		(0xCBB9 <= code && code <= 0xCBD3) || // Lo  [27] HANGUL SYLLABLE JJYUG..HANGUL SYLLABLE JJYUH
  		(0xCBD5 <= code && code <= 0xCBEF) || // Lo  [27] HANGUL SYLLABLE JJEUG..HANGUL SYLLABLE JJEUH
  		(0xCBF1 <= code && code <= 0xCC0B) || // Lo  [27] HANGUL SYLLABLE JJYIG..HANGUL SYLLABLE JJYIH
  		(0xCC0D <= code && code <= 0xCC27) || // Lo  [27] HANGUL SYLLABLE JJIG..HANGUL SYLLABLE JJIH
  		(0xCC29 <= code && code <= 0xCC43) || // Lo  [27] HANGUL SYLLABLE CAG..HANGUL SYLLABLE CAH
  		(0xCC45 <= code && code <= 0xCC5F) || // Lo  [27] HANGUL SYLLABLE CAEG..HANGUL SYLLABLE CAEH
  		(0xCC61 <= code && code <= 0xCC7B) || // Lo  [27] HANGUL SYLLABLE CYAG..HANGUL SYLLABLE CYAH
  		(0xCC7D <= code && code <= 0xCC97) || // Lo  [27] HANGUL SYLLABLE CYAEG..HANGUL SYLLABLE CYAEH
  		(0xCC99 <= code && code <= 0xCCB3) || // Lo  [27] HANGUL SYLLABLE CEOG..HANGUL SYLLABLE CEOH
  		(0xCCB5 <= code && code <= 0xCCCF) || // Lo  [27] HANGUL SYLLABLE CEG..HANGUL SYLLABLE CEH
  		(0xCCD1 <= code && code <= 0xCCEB) || // Lo  [27] HANGUL SYLLABLE CYEOG..HANGUL SYLLABLE CYEOH
  		(0xCCED <= code && code <= 0xCD07) || // Lo  [27] HANGUL SYLLABLE CYEG..HANGUL SYLLABLE CYEH
  		(0xCD09 <= code && code <= 0xCD23) || // Lo  [27] HANGUL SYLLABLE COG..HANGUL SYLLABLE COH
  		(0xCD25 <= code && code <= 0xCD3F) || // Lo  [27] HANGUL SYLLABLE CWAG..HANGUL SYLLABLE CWAH
  		(0xCD41 <= code && code <= 0xCD5B) || // Lo  [27] HANGUL SYLLABLE CWAEG..HANGUL SYLLABLE CWAEH
  		(0xCD5D <= code && code <= 0xCD77) || // Lo  [27] HANGUL SYLLABLE COEG..HANGUL SYLLABLE COEH
  		(0xCD79 <= code && code <= 0xCD93) || // Lo  [27] HANGUL SYLLABLE CYOG..HANGUL SYLLABLE CYOH
  		(0xCD95 <= code && code <= 0xCDAF) || // Lo  [27] HANGUL SYLLABLE CUG..HANGUL SYLLABLE CUH
  		(0xCDB1 <= code && code <= 0xCDCB) || // Lo  [27] HANGUL SYLLABLE CWEOG..HANGUL SYLLABLE CWEOH
  		(0xCDCD <= code && code <= 0xCDE7) || // Lo  [27] HANGUL SYLLABLE CWEG..HANGUL SYLLABLE CWEH
  		(0xCDE9 <= code && code <= 0xCE03) || // Lo  [27] HANGUL SYLLABLE CWIG..HANGUL SYLLABLE CWIH
  		(0xCE05 <= code && code <= 0xCE1F) || // Lo  [27] HANGUL SYLLABLE CYUG..HANGUL SYLLABLE CYUH
  		(0xCE21 <= code && code <= 0xCE3B) || // Lo  [27] HANGUL SYLLABLE CEUG..HANGUL SYLLABLE CEUH
  		(0xCE3D <= code && code <= 0xCE57) || // Lo  [27] HANGUL SYLLABLE CYIG..HANGUL SYLLABLE CYIH
  		(0xCE59 <= code && code <= 0xCE73) || // Lo  [27] HANGUL SYLLABLE CIG..HANGUL SYLLABLE CIH
  		(0xCE75 <= code && code <= 0xCE8F) || // Lo  [27] HANGUL SYLLABLE KAG..HANGUL SYLLABLE KAH
  		(0xCE91 <= code && code <= 0xCEAB) || // Lo  [27] HANGUL SYLLABLE KAEG..HANGUL SYLLABLE KAEH
  		(0xCEAD <= code && code <= 0xCEC7) || // Lo  [27] HANGUL SYLLABLE KYAG..HANGUL SYLLABLE KYAH
  		(0xCEC9 <= code && code <= 0xCEE3) || // Lo  [27] HANGUL SYLLABLE KYAEG..HANGUL SYLLABLE KYAEH
  		(0xCEE5 <= code && code <= 0xCEFF) || // Lo  [27] HANGUL SYLLABLE KEOG..HANGUL SYLLABLE KEOH
  		(0xCF01 <= code && code <= 0xCF1B) || // Lo  [27] HANGUL SYLLABLE KEG..HANGUL SYLLABLE KEH
  		(0xCF1D <= code && code <= 0xCF37) || // Lo  [27] HANGUL SYLLABLE KYEOG..HANGUL SYLLABLE KYEOH
  		(0xCF39 <= code && code <= 0xCF53) || // Lo  [27] HANGUL SYLLABLE KYEG..HANGUL SYLLABLE KYEH
  		(0xCF55 <= code && code <= 0xCF6F) || // Lo  [27] HANGUL SYLLABLE KOG..HANGUL SYLLABLE KOH
  		(0xCF71 <= code && code <= 0xCF8B) || // Lo  [27] HANGUL SYLLABLE KWAG..HANGUL SYLLABLE KWAH
  		(0xCF8D <= code && code <= 0xCFA7) || // Lo  [27] HANGUL SYLLABLE KWAEG..HANGUL SYLLABLE KWAEH
  		(0xCFA9 <= code && code <= 0xCFC3) || // Lo  [27] HANGUL SYLLABLE KOEG..HANGUL SYLLABLE KOEH
  		(0xCFC5 <= code && code <= 0xCFDF) || // Lo  [27] HANGUL SYLLABLE KYOG..HANGUL SYLLABLE KYOH
  		(0xCFE1 <= code && code <= 0xCFFB) || // Lo  [27] HANGUL SYLLABLE KUG..HANGUL SYLLABLE KUH
  		(0xCFFD <= code && code <= 0xD017) || // Lo  [27] HANGUL SYLLABLE KWEOG..HANGUL SYLLABLE KWEOH
  		(0xD019 <= code && code <= 0xD033) || // Lo  [27] HANGUL SYLLABLE KWEG..HANGUL SYLLABLE KWEH
  		(0xD035 <= code && code <= 0xD04F) || // Lo  [27] HANGUL SYLLABLE KWIG..HANGUL SYLLABLE KWIH
  		(0xD051 <= code && code <= 0xD06B) || // Lo  [27] HANGUL SYLLABLE KYUG..HANGUL SYLLABLE KYUH
  		(0xD06D <= code && code <= 0xD087) || // Lo  [27] HANGUL SYLLABLE KEUG..HANGUL SYLLABLE KEUH
  		(0xD089 <= code && code <= 0xD0A3) || // Lo  [27] HANGUL SYLLABLE KYIG..HANGUL SYLLABLE KYIH
  		(0xD0A5 <= code && code <= 0xD0BF) || // Lo  [27] HANGUL SYLLABLE KIG..HANGUL SYLLABLE KIH
  		(0xD0C1 <= code && code <= 0xD0DB) || // Lo  [27] HANGUL SYLLABLE TAG..HANGUL SYLLABLE TAH
  		(0xD0DD <= code && code <= 0xD0F7) || // Lo  [27] HANGUL SYLLABLE TAEG..HANGUL SYLLABLE TAEH
  		(0xD0F9 <= code && code <= 0xD113) || // Lo  [27] HANGUL SYLLABLE TYAG..HANGUL SYLLABLE TYAH
  		(0xD115 <= code && code <= 0xD12F) || // Lo  [27] HANGUL SYLLABLE TYAEG..HANGUL SYLLABLE TYAEH
  		(0xD131 <= code && code <= 0xD14B) || // Lo  [27] HANGUL SYLLABLE TEOG..HANGUL SYLLABLE TEOH
  		(0xD14D <= code && code <= 0xD167) || // Lo  [27] HANGUL SYLLABLE TEG..HANGUL SYLLABLE TEH
  		(0xD169 <= code && code <= 0xD183) || // Lo  [27] HANGUL SYLLABLE TYEOG..HANGUL SYLLABLE TYEOH
  		(0xD185 <= code && code <= 0xD19F) || // Lo  [27] HANGUL SYLLABLE TYEG..HANGUL SYLLABLE TYEH
  		(0xD1A1 <= code && code <= 0xD1BB) || // Lo  [27] HANGUL SYLLABLE TOG..HANGUL SYLLABLE TOH
  		(0xD1BD <= code && code <= 0xD1D7) || // Lo  [27] HANGUL SYLLABLE TWAG..HANGUL SYLLABLE TWAH
  		(0xD1D9 <= code && code <= 0xD1F3) || // Lo  [27] HANGUL SYLLABLE TWAEG..HANGUL SYLLABLE TWAEH
  		(0xD1F5 <= code && code <= 0xD20F) || // Lo  [27] HANGUL SYLLABLE TOEG..HANGUL SYLLABLE TOEH
  		(0xD211 <= code && code <= 0xD22B) || // Lo  [27] HANGUL SYLLABLE TYOG..HANGUL SYLLABLE TYOH
  		(0xD22D <= code && code <= 0xD247) || // Lo  [27] HANGUL SYLLABLE TUG..HANGUL SYLLABLE TUH
  		(0xD249 <= code && code <= 0xD263) || // Lo  [27] HANGUL SYLLABLE TWEOG..HANGUL SYLLABLE TWEOH
  		(0xD265 <= code && code <= 0xD27F) || // Lo  [27] HANGUL SYLLABLE TWEG..HANGUL SYLLABLE TWEH
  		(0xD281 <= code && code <= 0xD29B) || // Lo  [27] HANGUL SYLLABLE TWIG..HANGUL SYLLABLE TWIH
  		(0xD29D <= code && code <= 0xD2B7) || // Lo  [27] HANGUL SYLLABLE TYUG..HANGUL SYLLABLE TYUH
  		(0xD2B9 <= code && code <= 0xD2D3) || // Lo  [27] HANGUL SYLLABLE TEUG..HANGUL SYLLABLE TEUH
  		(0xD2D5 <= code && code <= 0xD2EF) || // Lo  [27] HANGUL SYLLABLE TYIG..HANGUL SYLLABLE TYIH
  		(0xD2F1 <= code && code <= 0xD30B) || // Lo  [27] HANGUL SYLLABLE TIG..HANGUL SYLLABLE TIH
  		(0xD30D <= code && code <= 0xD327) || // Lo  [27] HANGUL SYLLABLE PAG..HANGUL SYLLABLE PAH
  		(0xD329 <= code && code <= 0xD343) || // Lo  [27] HANGUL SYLLABLE PAEG..HANGUL SYLLABLE PAEH
  		(0xD345 <= code && code <= 0xD35F) || // Lo  [27] HANGUL SYLLABLE PYAG..HANGUL SYLLABLE PYAH
  		(0xD361 <= code && code <= 0xD37B) || // Lo  [27] HANGUL SYLLABLE PYAEG..HANGUL SYLLABLE PYAEH
  		(0xD37D <= code && code <= 0xD397) || // Lo  [27] HANGUL SYLLABLE PEOG..HANGUL SYLLABLE PEOH
  		(0xD399 <= code && code <= 0xD3B3) || // Lo  [27] HANGUL SYLLABLE PEG..HANGUL SYLLABLE PEH
  		(0xD3B5 <= code && code <= 0xD3CF) || // Lo  [27] HANGUL SYLLABLE PYEOG..HANGUL SYLLABLE PYEOH
  		(0xD3D1 <= code && code <= 0xD3EB) || // Lo  [27] HANGUL SYLLABLE PYEG..HANGUL SYLLABLE PYEH
  		(0xD3ED <= code && code <= 0xD407) || // Lo  [27] HANGUL SYLLABLE POG..HANGUL SYLLABLE POH
  		(0xD409 <= code && code <= 0xD423) || // Lo  [27] HANGUL SYLLABLE PWAG..HANGUL SYLLABLE PWAH
  		(0xD425 <= code && code <= 0xD43F) || // Lo  [27] HANGUL SYLLABLE PWAEG..HANGUL SYLLABLE PWAEH
  		(0xD441 <= code && code <= 0xD45B) || // Lo  [27] HANGUL SYLLABLE POEG..HANGUL SYLLABLE POEH
  		(0xD45D <= code && code <= 0xD477) || // Lo  [27] HANGUL SYLLABLE PYOG..HANGUL SYLLABLE PYOH
  		(0xD479 <= code && code <= 0xD493) || // Lo  [27] HANGUL SYLLABLE PUG..HANGUL SYLLABLE PUH
  		(0xD495 <= code && code <= 0xD4AF) || // Lo  [27] HANGUL SYLLABLE PWEOG..HANGUL SYLLABLE PWEOH
  		(0xD4B1 <= code && code <= 0xD4CB) || // Lo  [27] HANGUL SYLLABLE PWEG..HANGUL SYLLABLE PWEH
  		(0xD4CD <= code && code <= 0xD4E7) || // Lo  [27] HANGUL SYLLABLE PWIG..HANGUL SYLLABLE PWIH
  		(0xD4E9 <= code && code <= 0xD503) || // Lo  [27] HANGUL SYLLABLE PYUG..HANGUL SYLLABLE PYUH
  		(0xD505 <= code && code <= 0xD51F) || // Lo  [27] HANGUL SYLLABLE PEUG..HANGUL SYLLABLE PEUH
  		(0xD521 <= code && code <= 0xD53B) || // Lo  [27] HANGUL SYLLABLE PYIG..HANGUL SYLLABLE PYIH
  		(0xD53D <= code && code <= 0xD557) || // Lo  [27] HANGUL SYLLABLE PIG..HANGUL SYLLABLE PIH
  		(0xD559 <= code && code <= 0xD573) || // Lo  [27] HANGUL SYLLABLE HAG..HANGUL SYLLABLE HAH
  		(0xD575 <= code && code <= 0xD58F) || // Lo  [27] HANGUL SYLLABLE HAEG..HANGUL SYLLABLE HAEH
  		(0xD591 <= code && code <= 0xD5AB) || // Lo  [27] HANGUL SYLLABLE HYAG..HANGUL SYLLABLE HYAH
  		(0xD5AD <= code && code <= 0xD5C7) || // Lo  [27] HANGUL SYLLABLE HYAEG..HANGUL SYLLABLE HYAEH
  		(0xD5C9 <= code && code <= 0xD5E3) || // Lo  [27] HANGUL SYLLABLE HEOG..HANGUL SYLLABLE HEOH
  		(0xD5E5 <= code && code <= 0xD5FF) || // Lo  [27] HANGUL SYLLABLE HEG..HANGUL SYLLABLE HEH
  		(0xD601 <= code && code <= 0xD61B) || // Lo  [27] HANGUL SYLLABLE HYEOG..HANGUL SYLLABLE HYEOH
  		(0xD61D <= code && code <= 0xD637) || // Lo  [27] HANGUL SYLLABLE HYEG..HANGUL SYLLABLE HYEH
  		(0xD639 <= code && code <= 0xD653) || // Lo  [27] HANGUL SYLLABLE HOG..HANGUL SYLLABLE HOH
  		(0xD655 <= code && code <= 0xD66F) || // Lo  [27] HANGUL SYLLABLE HWAG..HANGUL SYLLABLE HWAH
  		(0xD671 <= code && code <= 0xD68B) || // Lo  [27] HANGUL SYLLABLE HWAEG..HANGUL SYLLABLE HWAEH
  		(0xD68D <= code && code <= 0xD6A7) || // Lo  [27] HANGUL SYLLABLE HOEG..HANGUL SYLLABLE HOEH
  		(0xD6A9 <= code && code <= 0xD6C3) || // Lo  [27] HANGUL SYLLABLE HYOG..HANGUL SYLLABLE HYOH
  		(0xD6C5 <= code && code <= 0xD6DF) || // Lo  [27] HANGUL SYLLABLE HUG..HANGUL SYLLABLE HUH
  		(0xD6E1 <= code && code <= 0xD6FB) || // Lo  [27] HANGUL SYLLABLE HWEOG..HANGUL SYLLABLE HWEOH
  		(0xD6FD <= code && code <= 0xD717) || // Lo  [27] HANGUL SYLLABLE HWEG..HANGUL SYLLABLE HWEH
  		(0xD719 <= code && code <= 0xD733) || // Lo  [27] HANGUL SYLLABLE HWIG..HANGUL SYLLABLE HWIH
  		(0xD735 <= code && code <= 0xD74F) || // Lo  [27] HANGUL SYLLABLE HYUG..HANGUL SYLLABLE HYUH
  		(0xD751 <= code && code <= 0xD76B) || // Lo  [27] HANGUL SYLLABLE HEUG..HANGUL SYLLABLE HEUH
  		(0xD76D <= code && code <= 0xD787) || // Lo  [27] HANGUL SYLLABLE HYIG..HANGUL SYLLABLE HYIH
  		(0xD789 <= code && code <= 0xD7A3) // Lo  [27] HANGUL SYLLABLE HIG..HANGUL SYLLABLE HIH
  		){
  			return LVT;
  		}

  		if(
  		0x261D == code || // So       WHITE UP POINTING INDEX
  		0x26F9 == code || // So       PERSON WITH BALL
  		(0x270A <= code && code <= 0x270D) || // So   [4] RAISED FIST..WRITING HAND
  		0x1F385 == code || // So       FATHER CHRISTMAS
  		(0x1F3C2 <= code && code <= 0x1F3C4) || // So   [3] SNOWBOARDER..SURFER
  		0x1F3C7 == code || // So       HORSE RACING
  		(0x1F3CA <= code && code <= 0x1F3CC) || // So   [3] SWIMMER..GOLFER
  		(0x1F442 <= code && code <= 0x1F443) || // So   [2] EAR..NOSE
  		(0x1F446 <= code && code <= 0x1F450) || // So  [11] WHITE UP POINTING BACKHAND INDEX..OPEN HANDS SIGN
  		0x1F46E == code || // So       POLICE OFFICER
  		(0x1F470 <= code && code <= 0x1F478) || // So   [9] BRIDE WITH VEIL..PRINCESS
  		0x1F47C == code || // So       BABY ANGEL
  		(0x1F481 <= code && code <= 0x1F483) || // So   [3] INFORMATION DESK PERSON..DANCER
  		(0x1F485 <= code && code <= 0x1F487) || // So   [3] NAIL POLISH..HAIRCUT
  		0x1F4AA == code || // So       FLEXED BICEPS
  		(0x1F574 <= code && code <= 0x1F575) || // So   [2] MAN IN BUSINESS SUIT LEVITATING..SLEUTH OR SPY
  		0x1F57A == code || // So       MAN DANCING
  		0x1F590 == code || // So       RAISED HAND WITH FINGERS SPLAYED
  		(0x1F595 <= code && code <= 0x1F596) || // So   [2] REVERSED HAND WITH MIDDLE FINGER EXTENDED..RAISED HAND WITH PART BETWEEN MIDDLE AND RING FINGERS
  		(0x1F645 <= code && code <= 0x1F647) || // So   [3] FACE WITH NO GOOD GESTURE..PERSON BOWING DEEPLY
  		(0x1F64B <= code && code <= 0x1F64F) || // So   [5] HAPPY PERSON RAISING ONE HAND..PERSON WITH FOLDED HANDS
  		0x1F6A3 == code || // So       ROWBOAT
  		(0x1F6B4 <= code && code <= 0x1F6B6) || // So   [3] BICYCLIST..PEDESTRIAN
  		0x1F6C0 == code || // So       BATH
  		0x1F6CC == code || // So       SLEEPING ACCOMMODATION
  		(0x1F918 <= code && code <= 0x1F91C) || // So   [5] SIGN OF THE HORNS..RIGHT-FACING FIST
  		(0x1F91E <= code && code <= 0x1F91F) || // So   [2] HAND WITH INDEX AND MIDDLE FINGERS CROSSED..I LOVE YOU HAND SIGN
  		0x1F926 == code || // So       FACE PALM
  		(0x1F930 <= code && code <= 0x1F939) || // So  [10] PREGNANT WOMAN..JUGGLING
  		(0x1F93D <= code && code <= 0x1F93E) || // So   [2] WATER POLO..HANDBALL
  		(0x1F9D1 <= code && code <= 0x1F9DD) // So  [13] ADULT..ELF
  		){
  			return E_Base;
  		}

  		if(
  		(0x1F3FB <= code && code <= 0x1F3FF) // Sk   [5] EMOJI MODIFIER FITZPATRICK TYPE-1-2..EMOJI MODIFIER FITZPATRICK TYPE-6
  		){
  			return E_Modifier;
  		}

  		if(
  		0x200D == code // Cf       ZERO WIDTH JOINER
  		){
  			return ZWJ;
  		}

  		if(
  		0x2640 == code || // So       FEMALE SIGN
  		0x2642 == code || // So       MALE SIGN
  		(0x2695 <= code && code <= 0x2696) || // So   [2] STAFF OF AESCULAPIUS..SCALES
  		0x2708 == code || // So       AIRPLANE
  		0x2764 == code || // So       HEAVY BLACK HEART
  		0x1F308 == code || // So       RAINBOW
  		0x1F33E == code || // So       EAR OF RICE
  		0x1F373 == code || // So       COOKING
  		0x1F393 == code || // So       GRADUATION CAP
  		0x1F3A4 == code || // So       MICROPHONE
  		0x1F3A8 == code || // So       ARTIST PALETTE
  		0x1F3EB == code || // So       SCHOOL
  		0x1F3ED == code || // So       FACTORY
  		0x1F48B == code || // So       KISS MARK
  		(0x1F4BB <= code && code <= 0x1F4BC) || // So   [2] PERSONAL COMPUTER..BRIEFCASE
  		0x1F527 == code || // So       WRENCH
  		0x1F52C == code || // So       MICROSCOPE
  		0x1F5E8 == code || // So       LEFT SPEECH BUBBLE
  		0x1F680 == code || // So       ROCKET
  		0x1F692 == code // So       FIRE ENGINE
  		){
  			return Glue_After_Zwj;
  		}

  		if(
  		(0x1F466 <= code && code <= 0x1F469) // So   [4] BOY..WOMAN
  		){
  			return E_Base_GAZ;
  		}


  		//all unlisted characters have a grapheme break property of "Other"
  		return Other;
  	}
  	return this;
  }

  // A glyph represents a single character in a particular label.  It may or may
  // not have a billboard, depending on whether the texture info has an index into
  // the the label collection's texture atlas.  Invisible characters have no texture, and
  // no billboard.  However, it always has a valid dimensions object.
  function Glyph() {
    this.textureInfo = undefined;
    this.dimensions = undefined;
    this.billboard = undefined;
  }

  // GlyphTextureInfo represents a single character, drawn in a particular style,
  // shared and reference counted across all labels.  It may or may not have an
  // index into the label collection's texture atlas, depending on whether the character
  // has both width and height, but it always has a valid dimensions object.
  function GlyphTextureInfo(labelCollection, index, dimensions) {
    this.labelCollection = labelCollection;
    this.index = index;
    this.dimensions = dimensions;
  }

  // Traditionally, leading is %20 of the font size.
  var defaultLineSpacingPercent = 1.2;

  var whitePixelCanvasId = "ID_WHITE_PIXEL";
  var whitePixelSize = new Cartesian2(4, 4);
  var whitePixelBoundingRegion = new BoundingRectangle(1, 1, 1, 1);

  function addWhitePixelCanvas(textureAtlas, labelCollection) {
    var canvas = document.createElement("canvas");
    canvas.width = whitePixelSize.x;
    canvas.height = whitePixelSize.y;

    var context2D = canvas.getContext("2d");
    context2D.fillStyle = "#fff";
    context2D.fillRect(0, 0, canvas.width, canvas.height);

    textureAtlas.addImage(whitePixelCanvasId, canvas).then(function (index) {
      labelCollection._whitePixelIndex = index;
    });
  }

  // reusable object for calling writeTextToCanvas
  var writeTextToCanvasParameters = {};
  function createGlyphCanvas(
    character,
    font,
    fillColor,
    outlineColor,
    outlineWidth,
    style,
    verticalOrigin
  ) {
    writeTextToCanvasParameters.font = font;
    writeTextToCanvasParameters.fillColor = fillColor;
    writeTextToCanvasParameters.strokeColor = outlineColor;
    writeTextToCanvasParameters.strokeWidth = outlineWidth;
    // Setting the padding to something bigger is necessary to get enough space for the outlining.
    writeTextToCanvasParameters.padding = SDFSettings$1.PADDING;

    if (verticalOrigin === VerticalOrigin$1.CENTER) {
      writeTextToCanvasParameters.textBaseline = "middle";
    } else if (verticalOrigin === VerticalOrigin$1.TOP) {
      writeTextToCanvasParameters.textBaseline = "top";
    } else {
      // VerticalOrigin.BOTTOM and VerticalOrigin.BASELINE
      writeTextToCanvasParameters.textBaseline = "bottom";
    }

    writeTextToCanvasParameters.fill =
      style === LabelStyle$1.FILL || style === LabelStyle$1.FILL_AND_OUTLINE;
    writeTextToCanvasParameters.stroke =
      style === LabelStyle$1.OUTLINE || style === LabelStyle$1.FILL_AND_OUTLINE;
    writeTextToCanvasParameters.backgroundColor = Color.BLACK;

    return writeTextToCanvas(character, writeTextToCanvasParameters);
  }

  function unbindGlyph(labelCollection, glyph) {
    glyph.textureInfo = undefined;
    glyph.dimensions = undefined;

    var billboard = glyph.billboard;
    if (defined(billboard)) {
      billboard.show = false;
      billboard.image = undefined;
      if (defined(billboard._removeCallbackFunc)) {
        billboard._removeCallbackFunc();
        billboard._removeCallbackFunc = undefined;
      }
      labelCollection._spareBillboards.push(billboard);
      glyph.billboard = undefined;
    }
  }

  function addGlyphToTextureAtlas(textureAtlas, id, canvas, glyphTextureInfo) {
    textureAtlas.addImage(id, canvas).then(function (index) {
      glyphTextureInfo.index = index;
    });
  }

  var splitter = new GraphemeSplitter();

  function rebindAllGlyphs$1(labelCollection, label) {
    var text = label._renderedText;
    var graphemes = splitter.splitGraphemes(text);
    var textLength = graphemes.length;
    var glyphs = label._glyphs;
    var glyphsLength = glyphs.length;

    var glyph;
    var glyphIndex;
    var textIndex;

    // Compute a font size scale relative to the sdf font generated size.
    label._relativeSize = label._fontSize / SDFSettings$1.FONT_SIZE;

    // if we have more glyphs than needed, unbind the extras.
    if (textLength < glyphsLength) {
      for (glyphIndex = textLength; glyphIndex < glyphsLength; ++glyphIndex) {
        unbindGlyph(labelCollection, glyphs[glyphIndex]);
      }
    }

    // presize glyphs to match the new text length
    glyphs.length = textLength;

    var showBackground =
      label._showBackground && text.split("\n").join("").length > 0;
    var backgroundBillboard = label._backgroundBillboard;
    var backgroundBillboardCollection =
      labelCollection._backgroundBillboardCollection;
    if (!showBackground) {
      if (defined(backgroundBillboard)) {
        backgroundBillboardCollection.remove(backgroundBillboard);
        label._backgroundBillboard = backgroundBillboard = undefined;
      }
    } else {
      if (!defined(backgroundBillboard)) {
        backgroundBillboard = backgroundBillboardCollection.add({
          collection: labelCollection,
          image: whitePixelCanvasId,
          imageSubRegion: whitePixelBoundingRegion,
        });
        label._backgroundBillboard = backgroundBillboard;
      }

      backgroundBillboard.color = label._backgroundColor;
      backgroundBillboard.show = label._show;
      backgroundBillboard.position = label._position;
      backgroundBillboard.eyeOffset = label._eyeOffset;
      backgroundBillboard.pixelOffset = label._pixelOffset;
      backgroundBillboard.horizontalOrigin = HorizontalOrigin$1.LEFT;
      backgroundBillboard.verticalOrigin = label._verticalOrigin;
      backgroundBillboard.heightReference = label._heightReference;
      backgroundBillboard.scale = label.totalScale;
      backgroundBillboard.pickPrimitive = label;
      backgroundBillboard.id = label._id;
      backgroundBillboard.translucencyByDistance = label._translucencyByDistance;
      backgroundBillboard.pixelOffsetScaleByDistance =
        label._pixelOffsetScaleByDistance;
      backgroundBillboard.scaleByDistance = label._scaleByDistance;
      backgroundBillboard.distanceDisplayCondition =
        label._distanceDisplayCondition;
      backgroundBillboard.disableDepthTestDistance =
        label._disableDepthTestDistance;
    }

    var glyphTextureCache = labelCollection._glyphTextureCache;

    // walk the text looking for new characters (creating new glyphs for each)
    // or changed characters (rebinding existing glyphs)
    for (textIndex = 0; textIndex < textLength; ++textIndex) {
      var character = graphemes[textIndex];
      var verticalOrigin = label._verticalOrigin;

      var id = JSON.stringify([
        character,
        label._fontFamily,
        label._fontStyle,
        label._fontWeight,
        +verticalOrigin,
      ]);

      var glyphTextureInfo = glyphTextureCache[id];
      if (!defined(glyphTextureInfo)) {
        var glyphFont =
          label._fontStyle +
          " " +
          label._fontWeight +
          " " +
          SDFSettings$1.FONT_SIZE +
          "px " +
          label._fontFamily;

        var canvas = createGlyphCanvas(
          character,
          glyphFont,
          Color.WHITE,
          Color.WHITE,
          0.0,
          LabelStyle$1.FILL,
          verticalOrigin
        );

        glyphTextureInfo = new GlyphTextureInfo(
          labelCollection,
          -1,
          canvas.dimensions
        );
        glyphTextureCache[id] = glyphTextureInfo;

        if (canvas.width > 0 && canvas.height > 0) {
          var sdfValues = calcSDF(canvas, {
            cutoff: SDFSettings$1.CUTOFF,
            radius: SDFSettings$1.RADIUS,
          });

          var ctx = canvas.getContext("2d");
          var canvasWidth = canvas.width;
          var canvasHeight = canvas.height;
          var imgData = ctx.getImageData(0, 0, canvasWidth, canvasHeight);
          for (var i = 0; i < canvasWidth; i++) {
            for (var j = 0; j < canvasHeight; j++) {
              var baseIndex = j * canvasWidth + i;
              var alpha = sdfValues[baseIndex] * 255;
              var imageIndex = baseIndex * 4;
              imgData.data[imageIndex + 0] = alpha;
              imgData.data[imageIndex + 1] = alpha;
              imgData.data[imageIndex + 2] = alpha;
              imgData.data[imageIndex + 3] = alpha;
            }
          }
          ctx.putImageData(imgData, 0, 0);
          if (character !== " ") {
            addGlyphToTextureAtlas(
              labelCollection._textureAtlas,
              id,
              canvas,
              glyphTextureInfo
            );
          }
        }
      }

      glyph = glyphs[textIndex];

      if (defined(glyph)) {
        // clean up leftover information from the previous glyph
        if (glyphTextureInfo.index === -1) {
          // no texture, and therefore no billboard, for this glyph.
          // so, completely unbind glyph.
          unbindGlyph(labelCollection, glyph);
        } else if (defined(glyph.textureInfo)) {
          // we have a texture and billboard.  If we had one before, release
          // our reference to that texture info, but reuse the billboard.
          glyph.textureInfo = undefined;
        }
      } else {
        // create a glyph object
        glyph = new Glyph();
        glyphs[textIndex] = glyph;
      }

      glyph.textureInfo = glyphTextureInfo;
      glyph.dimensions = glyphTextureInfo.dimensions;

      // if we have a texture, configure the existing billboard, or obtain one
      if (glyphTextureInfo.index !== -1) {
        var billboard = glyph.billboard;
        var spareBillboards = labelCollection._spareBillboards;
        if (!defined(billboard)) {
          if (spareBillboards.length > 0) {
            billboard = spareBillboards.pop();
          } else {
            billboard = labelCollection._billboardCollection.add({
              collection: labelCollection,
            });
            billboard._labelDimensions = new Cartesian2();
            billboard._labelTranslate = new Cartesian2();
          }
          glyph.billboard = billboard;
        }

        billboard.show = label._show;
        billboard.position = label._position;
        billboard.eyeOffset = label._eyeOffset;
        billboard.pixelOffset = label._pixelOffset;
        billboard.horizontalOrigin = HorizontalOrigin$1.LEFT;
        billboard.verticalOrigin = label._verticalOrigin;
        billboard.heightReference = label._heightReference;
        billboard.scale = label.totalScale;
        billboard.pickPrimitive = label;
        billboard.id = label._id;
        billboard.image = id;
        billboard.translucencyByDistance = label._translucencyByDistance;
        billboard.pixelOffsetScaleByDistance = label._pixelOffsetScaleByDistance;
        billboard.scaleByDistance = label._scaleByDistance;
        billboard.distanceDisplayCondition = label._distanceDisplayCondition;
        billboard.disableDepthTestDistance = label._disableDepthTestDistance;
        billboard._batchIndex = label._batchIndex;
        billboard.outlineColor = label.outlineColor;
        if (label.style === LabelStyle$1.FILL_AND_OUTLINE) {
          billboard.color = label._fillColor;
          billboard.outlineWidth = label.outlineWidth;
        } else if (label.style === LabelStyle$1.FILL) {
          billboard.color = label._fillColor;
          billboard.outlineWidth = 0.0;
        } else if (label.style === LabelStyle$1.OUTLINE) {
          billboard.color = Color.TRANSPARENT;
          billboard.outlineWidth = label.outlineWidth;
        }
      }
    }

    // changing glyphs will cause the position of the
    // glyphs to change, since different characters have different widths
    label._repositionAllGlyphs = true;
  }

  function calculateWidthOffset(lineWidth, horizontalOrigin, backgroundPadding) {
    if (horizontalOrigin === HorizontalOrigin$1.CENTER) {
      return -lineWidth / 2;
    } else if (horizontalOrigin === HorizontalOrigin$1.RIGHT) {
      return -(lineWidth + backgroundPadding.x);
    }
    return backgroundPadding.x;
  }

  // reusable Cartesian2 instances
  var glyphPixelOffset = new Cartesian2();
  var scratchBackgroundPadding = new Cartesian2();

  function repositionAllGlyphs$1(label) {
    var glyphs = label._glyphs;
    var text = label._renderedText;
    var glyph;
    var dimensions;
    var lastLineWidth = 0;
    var maxLineWidth = 0;
    var lineWidths = [];
    var maxGlyphDescent = Number.NEGATIVE_INFINITY;
    var maxGlyphY = 0;
    var numberOfLines = 1;
    var glyphIndex;
    var glyphLength = glyphs.length;

    var backgroundBillboard = label._backgroundBillboard;
    var backgroundPadding = Cartesian2.clone(
      defined(backgroundBillboard) ? label._backgroundPadding : Cartesian2.ZERO,
      scratchBackgroundPadding
    );

    // We need to scale the background padding, which is specified in pixels by the inverse of the relative size so it is scaled properly.
    backgroundPadding.x /= label._relativeSize;
    backgroundPadding.y /= label._relativeSize;

    for (glyphIndex = 0; glyphIndex < glyphLength; ++glyphIndex) {
      if (text.charAt(glyphIndex) === "\n") {
        lineWidths.push(lastLineWidth);
        ++numberOfLines;
        lastLineWidth = 0;
      } else {
        glyph = glyphs[glyphIndex];
        dimensions = glyph.dimensions;
        maxGlyphY = Math.max(maxGlyphY, dimensions.height - dimensions.descent);
        maxGlyphDescent = Math.max(maxGlyphDescent, dimensions.descent);

        //Computing the line width must also account for the kerning that occurs between letters.
        lastLineWidth += dimensions.width - dimensions.bounds.minx;
        if (glyphIndex < glyphLength - 1) {
          lastLineWidth += glyphs[glyphIndex + 1].dimensions.bounds.minx;
        }
        maxLineWidth = Math.max(maxLineWidth, lastLineWidth);
      }
    }
    lineWidths.push(lastLineWidth);
    var maxLineHeight = maxGlyphY + maxGlyphDescent;

    var scale = label.totalScale;
    var horizontalOrigin = label._horizontalOrigin;
    var verticalOrigin = label._verticalOrigin;
    var lineIndex = 0;
    var lineWidth = lineWidths[lineIndex];
    var widthOffset = calculateWidthOffset(
      lineWidth,
      horizontalOrigin,
      backgroundPadding
    );
    var lineSpacing = defaultLineSpacingPercent * maxLineHeight;
    var otherLinesHeight = lineSpacing * (numberOfLines - 1);
    var totalLineWidth = maxLineWidth;
    var totalLineHeight = maxLineHeight + otherLinesHeight;

    if (defined(backgroundBillboard)) {
      totalLineWidth += backgroundPadding.x * 2;
      totalLineHeight += backgroundPadding.y * 2;
      backgroundBillboard._labelHorizontalOrigin = horizontalOrigin;
    }

    glyphPixelOffset.x = widthOffset * scale;
    glyphPixelOffset.y = 0;

    var firstCharOfLine = true;

    var lineOffsetY = 0;
    for (glyphIndex = 0; glyphIndex < glyphLength; ++glyphIndex) {
      if (text.charAt(glyphIndex) === "\n") {
        ++lineIndex;
        lineOffsetY += lineSpacing;
        lineWidth = lineWidths[lineIndex];
        widthOffset = calculateWidthOffset(
          lineWidth,
          horizontalOrigin,
          backgroundPadding
        );
        glyphPixelOffset.x = widthOffset * scale;
        firstCharOfLine = true;
      } else {
        glyph = glyphs[glyphIndex];
        dimensions = glyph.dimensions;

        if (verticalOrigin === VerticalOrigin$1.TOP) {
          glyphPixelOffset.y =
            dimensions.height - maxGlyphY - backgroundPadding.y;
          glyphPixelOffset.y += SDFSettings$1.PADDING;
        } else if (verticalOrigin === VerticalOrigin$1.CENTER) {
          glyphPixelOffset.y =
            (otherLinesHeight + dimensions.height - maxGlyphY) / 2;
        } else if (verticalOrigin === VerticalOrigin$1.BASELINE) {
          glyphPixelOffset.y = otherLinesHeight;
          glyphPixelOffset.y -= SDFSettings$1.PADDING;
        } else {
          // VerticalOrigin.BOTTOM
          glyphPixelOffset.y =
            otherLinesHeight + maxGlyphDescent + backgroundPadding.y;
          glyphPixelOffset.y -= SDFSettings$1.PADDING;
        }
        glyphPixelOffset.y =
          (glyphPixelOffset.y - dimensions.descent - lineOffsetY) * scale;

        // Handle any offsets for the first character of the line since the bounds might not be right on the bottom left pixel.
        if (firstCharOfLine) {
          glyphPixelOffset.x -= SDFSettings$1.PADDING * scale;
          firstCharOfLine = false;
        }

        if (defined(glyph.billboard)) {
          glyph.billboard._setTranslate(glyphPixelOffset);
          glyph.billboard._labelDimensions.x = totalLineWidth;
          glyph.billboard._labelDimensions.y = totalLineHeight;
          glyph.billboard._labelHorizontalOrigin = horizontalOrigin;
        }

        //Compute the next x offset taking into account the kerning performed
        //on both the current letter as well as the next letter to be drawn
        //as well as any applied scale.
        if (glyphIndex < glyphLength - 1) {
          var nextGlyph = glyphs[glyphIndex + 1];
          glyphPixelOffset.x +=
            (dimensions.width -
              dimensions.bounds.minx +
              nextGlyph.dimensions.bounds.minx) *
            scale;
        }
      }
    }

    if (defined(backgroundBillboard) && text.split("\n").join("").length > 0) {
      if (horizontalOrigin === HorizontalOrigin$1.CENTER) {
        widthOffset = -maxLineWidth / 2 - backgroundPadding.x;
      } else if (horizontalOrigin === HorizontalOrigin$1.RIGHT) {
        widthOffset = -(maxLineWidth + backgroundPadding.x * 2);
      } else {
        widthOffset = 0;
      }
      glyphPixelOffset.x = widthOffset * scale;

      if (verticalOrigin === VerticalOrigin$1.TOP) {
        glyphPixelOffset.y = maxLineHeight - maxGlyphY - maxGlyphDescent;
      } else if (verticalOrigin === VerticalOrigin$1.CENTER) {
        glyphPixelOffset.y = (maxLineHeight - maxGlyphY) / 2 - maxGlyphDescent;
      } else if (verticalOrigin === VerticalOrigin$1.BASELINE) {
        glyphPixelOffset.y = -backgroundPadding.y - maxGlyphDescent;
      } else {
        // VerticalOrigin.BOTTOM
        glyphPixelOffset.y = 0;
      }
      glyphPixelOffset.y = glyphPixelOffset.y * scale;

      backgroundBillboard.width = totalLineWidth;
      backgroundBillboard.height = totalLineHeight;
      backgroundBillboard._setTranslate(glyphPixelOffset);
      backgroundBillboard._labelTranslate = Cartesian2.clone(
        glyphPixelOffset,
        backgroundBillboard._labelTranslate
      );
    }

    if (label.heightReference === HeightReference$1.CLAMP_TO_GROUND) {
      for (glyphIndex = 0; glyphIndex < glyphLength; ++glyphIndex) {
        glyph = glyphs[glyphIndex];
        var billboard = glyph.billboard;
        if (defined(billboard)) {
          billboard._labelTranslate = Cartesian2.clone(
            glyphPixelOffset,
            billboard._labelTranslate
          );
        }
      }
    }
  }

  function destroyLabel(labelCollection, label) {
    var glyphs = label._glyphs;
    for (var i = 0, len = glyphs.length; i < len; ++i) {
      unbindGlyph(labelCollection, glyphs[i]);
    }
    if (defined(label._backgroundBillboard)) {
      labelCollection._backgroundBillboardCollection.remove(
        label._backgroundBillboard
      );
      label._backgroundBillboard = undefined;
    }
    label._labelCollection = undefined;

    if (defined(label._removeCallbackFunc)) {
      label._removeCallbackFunc();
    }

    destroyObject(label);
  }

  /**
   * A renderable collection of labels.  Labels are viewport-aligned text positioned in the 3D scene.
   * Each label can have a different font, color, scale, etc.
   * <br /><br />
   * <div align='center'>
   * <img src='Images/Label.png' width='400' height='300' /><br />
   * Example labels
   * </div>
   * <br /><br />
   * Labels are added and removed from the collection using {@link LabelCollection#add}
   * and {@link LabelCollection#remove}.
   *
   * @alias LabelCollection
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms each label from model to world coordinates.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {Scene} [options.scene] Must be passed in for labels that use the height reference property or will be depth tested against the globe.
   * @param {BlendOption} [options.blendOption=BlendOption.OPAQUE_AND_TRANSLUCENT] The label blending option. The default
   * is used for rendering both opaque and translucent labels. However, if either all of the labels are completely opaque or all are completely translucent,
   * setting the technique to BlendOption.OPAQUE or BlendOption.TRANSLUCENT can improve performance by up to 2x.
   *
   * @performance For best performance, prefer a few collections, each with many labels, to
   * many collections with only a few labels each.  Avoid having collections where some
   * labels change every frame and others do not; instead, create one or more collections
   * for static labels, and one or more collections for dynamic labels.
   *
   * @see LabelCollection#add
   * @see LabelCollection#remove
   * @see Label
   * @see BillboardCollection
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Labels.html|Cesium Sandcastle Labels Demo}
   *
   * @example
   * // Create a label collection with two labels
   * var labels = scene.primitives.add(new Cesium.LabelCollection());
   * labels.add({
   *   position : new Cesium.Cartesian3(1.0, 2.0, 3.0),
   *   text : 'A label'
   * });
   * labels.add({
   *   position : new Cesium.Cartesian3(4.0, 5.0, 6.0),
   *   text : 'Another label'
   * });
   */
  function LabelCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._scene = options.scene;
    this._batchTable = options.batchTable;

    this._textureAtlas = undefined;
    this._backgroundTextureAtlas = undefined;
    this._whitePixelIndex = undefined;

    this._backgroundBillboardCollection = new BillboardCollection({
      scene: this._scene,
    });
    this._backgroundBillboardCollection.destroyTextureAtlas = false;

    this._billboardCollection = new BillboardCollection({
      scene: this._scene,
      batchTable: this._batchTable,
    });
    this._billboardCollection.destroyTextureAtlas = false;
    this._billboardCollection._sdf = true;

    this._spareBillboards = [];
    this._glyphTextureCache = {};
    this._labels = [];
    this._labelsToUpdate = [];
    this._totalGlyphCount = 0;

    this._highlightColor = Color.clone(Color.WHITE); // Only used by Vector3DTilePoints

    /**
     * The 4x4 transformation matrix that transforms each label in this collection from model to world coordinates.
     * When this is the identity matrix, the labels are drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type Matrix4
     * @default {@link Matrix4.IDENTITY}
     *
     * @example
     * var center = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
     * labels.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(center);
     * labels.add({
     *   position : new Cesium.Cartesian3(0.0, 0.0, 0.0),
     *   text     : 'Center'
     * });
     * labels.add({
     *   position : new Cesium.Cartesian3(1000000.0, 0.0, 0.0),
     *   text     : 'East'
     * });
     * labels.add({
     *   position : new Cesium.Cartesian3(0.0, 1000000.0, 0.0),
     *   text     : 'North'
     * });
     * labels.add({
     *   position : new Cesium.Cartesian3(0.0, 0.0, 1000000.0),
     *   text     : 'Up'
     * });
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * The label blending option. The default is used for rendering both opaque and translucent labels.
     * However, if either all of the labels are completely opaque or all are completely translucent,
     * setting the technique to BlendOption.OPAQUE or BlendOption.TRANSLUCENT can improve
     * performance by up to 2x.
     * @type {BlendOption}
     * @default BlendOption.OPAQUE_AND_TRANSLUCENT
     */
    this.blendOption = defaultValue(
      options.blendOption,
      BlendOption$1.OPAQUE_AND_TRANSLUCENT
    );
  }

  Object.defineProperties(LabelCollection.prototype, {
    /**
     * Returns the number of labels in this collection.  This is commonly used with
     * {@link LabelCollection#get} to iterate over all the labels
     * in the collection.
     * @memberof LabelCollection.prototype
     * @type {Number}
     */
    length: {
      get: function () {
        return this._labels.length;
      },
    },
  });

  /**
   * Creates and adds a label with the specified initial properties to the collection.
   * The added label is returned so it can be modified or removed from the collection later.
   *
   * @param {Object} [options] A template describing the label's properties as shown in Example 1.
   * @returns {Label} The label that was added to the collection.
   *
   * @performance Calling <code>add</code> is expected constant time.  However, the collection's vertex buffer
   * is rewritten; this operations is <code>O(n)</code> and also incurs
   * CPU to GPU overhead.  For best performance, add as many billboards as possible before
   * calling <code>update</code>.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Example 1:  Add a label, specifying all the default values.
   * var l = labels.add({
   *   show : true,
   *   position : Cesium.Cartesian3.ZERO,
   *   text : '',
   *   font : '30px sans-serif',
   *   fillColor : Cesium.Color.WHITE,
   *   outlineColor : Cesium.Color.BLACK,
   *   outlineWidth : 1.0,
   *   showBackground : false,
   *   backgroundColor : new Cesium.Color(0.165, 0.165, 0.165, 0.8),
   *   backgroundPadding : new Cesium.Cartesian2(7, 5),
   *   style : Cesium.LabelStyle.FILL,
   *   pixelOffset : Cesium.Cartesian2.ZERO,
   *   eyeOffset : Cesium.Cartesian3.ZERO,
   *   horizontalOrigin : Cesium.HorizontalOrigin.LEFT,
   *   verticalOrigin : Cesium.VerticalOrigin.BASELINE,
   *   scale : 1.0,
   *   translucencyByDistance : undefined,
   *   pixelOffsetScaleByDistance : undefined,
   *   heightReference : HeightReference.NONE,
   *   distanceDisplayCondition : undefined
   * });
   *
   * @example
   * // Example 2:  Specify only the label's cartographic position,
   * // text, and font.
   * var l = labels.add({
   *   position : Cesium.Cartesian3.fromRadians(longitude, latitude, height),
   *   text : 'Hello World',
   *   font : '24px Helvetica',
   * });
   *
   * @see LabelCollection#remove
   * @see LabelCollection#removeAll
   */
  LabelCollection.prototype.add = function (options) {
    var label = new Label(options, this);

    this._labels.push(label);
    this._labelsToUpdate.push(label);

    return label;
  };

  /**
   * Removes a label from the collection.  Once removed, a label is no longer usable.
   *
   * @param {Label} label The label to remove.
   * @returns {Boolean} <code>true</code> if the label was removed; <code>false</code> if the label was not found in the collection.
   *
   * @performance Calling <code>remove</code> is expected constant time.  However, the collection's vertex buffer
   * is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.  For
   * best performance, remove as many labels as possible before calling <code>update</code>.
   * If you intend to temporarily hide a label, it is usually more efficient to call
   * {@link Label#show} instead of removing and re-adding the label.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * var l = labels.add(...);
   * labels.remove(l);  // Returns true
   *
   * @see LabelCollection#add
   * @see LabelCollection#removeAll
   * @see Label#show
   */
  LabelCollection.prototype.remove = function (label) {
    if (defined(label) && label._labelCollection === this) {
      var index = this._labels.indexOf(label);
      if (index !== -1) {
        this._labels.splice(index, 1);
        destroyLabel(this, label);
        return true;
      }
    }
    return false;
  };

  /**
   * Removes all labels from the collection.
   *
   * @performance <code>O(n)</code>.  It is more efficient to remove all the labels
   * from a collection and then add new ones than to create a new collection entirely.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * labels.add(...);
   * labels.add(...);
   * labels.removeAll();
   *
   * @see LabelCollection#add
   * @see LabelCollection#remove
   */
  LabelCollection.prototype.removeAll = function () {
    var labels = this._labels;

    for (var i = 0, len = labels.length; i < len; ++i) {
      destroyLabel(this, labels[i]);
    }

    labels.length = 0;
  };

  /**
   * Check whether this collection contains a given label.
   *
   * @param {Label} label The label to check for.
   * @returns {Boolean} true if this collection contains the label, false otherwise.
   *
   * @see LabelCollection#get
   *
   */
  LabelCollection.prototype.contains = function (label) {
    return defined(label) && label._labelCollection === this;
  };

  /**
   * Returns the label in the collection at the specified index.  Indices are zero-based
   * and increase as labels are added.  Removing a label shifts all labels after
   * it to the left, changing their indices.  This function is commonly used with
   * {@link LabelCollection#length} to iterate over all the labels
   * in the collection.
   *
   * @param {Number} index The zero-based index of the billboard.
   *
   * @returns {Label} The label at the specified index.
   *
   * @performance Expected constant time.  If labels were removed from the collection and
   * {@link Scene#render} was not called, an implicit <code>O(n)</code>
   * operation is performed.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Toggle the show property of every label in the collection
   * var len = labels.length;
   * for (var i = 0; i < len; ++i) {
   *   var l = billboards.get(i);
   *   l.show = !l.show;
   * }
   *
   * @see LabelCollection#length
   */
  LabelCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    return this._labels[index];
  };

  /**
   * @private
   *
   */
  LabelCollection.prototype.update = function (frameState) {
    var billboardCollection = this._billboardCollection;
    var backgroundBillboardCollection = this._backgroundBillboardCollection;

    billboardCollection.modelMatrix = this.modelMatrix;
    billboardCollection.debugShowBoundingVolume = this.debugShowBoundingVolume;
    backgroundBillboardCollection.modelMatrix = this.modelMatrix;
    backgroundBillboardCollection.debugShowBoundingVolume = this.debugShowBoundingVolume;

    var context = frameState.context;

    if (!defined(this._textureAtlas)) {
      this._textureAtlas = new TextureAtlas({
        context: context,
      });
      billboardCollection.textureAtlas = this._textureAtlas;
    }

    if (!defined(this._backgroundTextureAtlas)) {
      this._backgroundTextureAtlas = new TextureAtlas({
        context: context,
        initialSize: whitePixelSize,
      });
      backgroundBillboardCollection.textureAtlas = this._backgroundTextureAtlas;
      addWhitePixelCanvas(this._backgroundTextureAtlas, this);
    }

    var len = this._labelsToUpdate.length;
    for (var i = 0; i < len; ++i) {
      var label = this._labelsToUpdate[i];
      if (label.isDestroyed()) {
        continue;
      }

      var preUpdateGlyphCount = label._glyphs.length;

      if (label._rebindAllGlyphs) {
        rebindAllGlyphs$1(this, label);
        label._rebindAllGlyphs = false;
      }

      if (label._repositionAllGlyphs) {
        repositionAllGlyphs$1(label);
        label._repositionAllGlyphs = false;
      }

      var glyphCountDifference = label._glyphs.length - preUpdateGlyphCount;
      this._totalGlyphCount += glyphCountDifference;
    }

    var blendOption =
      backgroundBillboardCollection.length > 0
        ? BlendOption$1.TRANSLUCENT
        : this.blendOption;
    billboardCollection.blendOption = blendOption;
    backgroundBillboardCollection.blendOption = blendOption;

    billboardCollection._highlightColor = this._highlightColor;
    backgroundBillboardCollection._highlightColor = this._highlightColor;

    this._labelsToUpdate.length = 0;
    backgroundBillboardCollection.update(frameState);
    billboardCollection.update(frameState);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see LabelCollection#destroy
   */
  LabelCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * labels = labels && labels.destroy();
   *
   * @see LabelCollection#isDestroyed
   */
  LabelCollection.prototype.destroy = function () {
    this.removeAll();
    this._billboardCollection = this._billboardCollection.destroy();
    this._textureAtlas = this._textureAtlas && this._textureAtlas.destroy();
    this._backgroundBillboardCollection = this._backgroundBillboardCollection.destroy();
    this._backgroundTextureAtlas =
      this._backgroundTextureAtlas && this._backgroundTextureAtlas.destroy();

    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var PolylineVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec3 position2DHigh;\n\
attribute vec3 position2DLow;\n\
attribute vec3 prevPosition3DHigh;\n\
attribute vec3 prevPosition3DLow;\n\
attribute vec3 prevPosition2DHigh;\n\
attribute vec3 prevPosition2DLow;\n\
attribute vec3 nextPosition3DHigh;\n\
attribute vec3 nextPosition3DLow;\n\
attribute vec3 nextPosition2DHigh;\n\
attribute vec3 nextPosition2DLow;\n\
attribute vec4 texCoordExpandAndBatchIndex;\n\
varying vec2  v_st;\n\
varying float v_width;\n\
varying vec4 v_pickColor;\n\
varying float v_polylineAngle;\n\
void main()\n\
{\n\
float texCoord = texCoordExpandAndBatchIndex.x;\n\
float expandDir = texCoordExpandAndBatchIndex.y;\n\
bool usePrev = texCoordExpandAndBatchIndex.z < 0.0;\n\
float batchTableIndex = texCoordExpandAndBatchIndex.w;\n\
vec2 widthAndShow = batchTable_getWidthAndShow(batchTableIndex);\n\
float width = widthAndShow.x + 0.5;\n\
float show = widthAndShow.y;\n\
if (width < 1.0)\n\
{\n\
show = 0.0;\n\
}\n\
vec4 pickColor = batchTable_getPickColor(batchTableIndex);\n\
vec4 p, prev, next;\n\
if (czm_morphTime == 1.0)\n\
{\n\
p = czm_translateRelativeToEye(position3DHigh.xyz, position3DLow.xyz);\n\
prev = czm_translateRelativeToEye(prevPosition3DHigh.xyz, prevPosition3DLow.xyz);\n\
next = czm_translateRelativeToEye(nextPosition3DHigh.xyz, nextPosition3DLow.xyz);\n\
}\n\
else if (czm_morphTime == 0.0)\n\
{\n\
p = czm_translateRelativeToEye(position2DHigh.zxy, position2DLow.zxy);\n\
prev = czm_translateRelativeToEye(prevPosition2DHigh.zxy, prevPosition2DLow.zxy);\n\
next = czm_translateRelativeToEye(nextPosition2DHigh.zxy, nextPosition2DLow.zxy);\n\
}\n\
else\n\
{\n\
p = czm_columbusViewMorph(\n\
czm_translateRelativeToEye(position2DHigh.zxy, position2DLow.zxy),\n\
czm_translateRelativeToEye(position3DHigh.xyz, position3DLow.xyz),\n\
czm_morphTime);\n\
prev = czm_columbusViewMorph(\n\
czm_translateRelativeToEye(prevPosition2DHigh.zxy, prevPosition2DLow.zxy),\n\
czm_translateRelativeToEye(prevPosition3DHigh.xyz, prevPosition3DLow.xyz),\n\
czm_morphTime);\n\
next = czm_columbusViewMorph(\n\
czm_translateRelativeToEye(nextPosition2DHigh.zxy, nextPosition2DLow.zxy),\n\
czm_translateRelativeToEye(nextPosition3DHigh.xyz, nextPosition3DLow.xyz),\n\
czm_morphTime);\n\
}\n\
#ifdef DISTANCE_DISPLAY_CONDITION\n\
vec3 centerHigh = batchTable_getCenterHigh(batchTableIndex);\n\
vec4 centerLowAndRadius = batchTable_getCenterLowAndRadius(batchTableIndex);\n\
vec3 centerLow = centerLowAndRadius.xyz;\n\
float radius = centerLowAndRadius.w;\n\
vec2 distanceDisplayCondition = batchTable_getDistanceDisplayCondition(batchTableIndex);\n\
float lengthSq;\n\
if (czm_sceneMode == czm_sceneMode2D)\n\
{\n\
lengthSq = czm_eyeHeight2D.y;\n\
}\n\
else\n\
{\n\
vec4 center = czm_translateRelativeToEye(centerHigh.xyz, centerLow.xyz);\n\
lengthSq = max(0.0, dot(center.xyz, center.xyz) - radius * radius);\n\
}\n\
float nearSq = distanceDisplayCondition.x * distanceDisplayCondition.x;\n\
float farSq = distanceDisplayCondition.y * distanceDisplayCondition.y;\n\
if (lengthSq < nearSq || lengthSq > farSq)\n\
{\n\
show = 0.0;\n\
}\n\
#endif\n\
float polylineAngle;\n\
vec4 positionWC = getPolylineWindowCoordinates(p, prev, next, expandDir, width, usePrev, polylineAngle);\n\
gl_Position = czm_viewportOrthographic * positionWC * show;\n\
v_st.s = texCoord;\n\
v_st.t = czm_writeNonPerspective(clamp(expandDir, 0.0, 1.0), gl_Position.w);\n\
v_width = width;\n\
v_pickColor = pickColor;\n\
v_polylineAngle = polylineAngle;\n\
}\n\
";

  /**
   * A renderable polyline. Create this by calling {@link PolylineCollection#add}
   *
   * @alias Polyline
   * @internalConstructor
   * @class
   *
   * @param {Object} options Object with the following properties:
   * @param {Boolean} [options.show=true] <code>true</code> if this polyline will be shown; otherwise, <code>false</code>.
   * @param {Number} [options.width=1.0] The width of the polyline in pixels.
   * @param {Boolean} [options.loop=false] Whether a line segment will be added between the last and first line positions to make this line a loop.
   * @param {Material} [options.material=Material.ColorType] The material.
   * @param {Cartesian3[]} [options.positions] The positions.
   * @param {Object} [options.id] The user-defined object to be returned when this polyline is picked.
   * @param {DistanceDisplayCondition} [options.distanceDisplayCondition] The condition specifying at what distance from the camera that this polyline will be displayed.
   * @param {PolylineCollection} polylineCollection The renderable polyline collection.
   *
   * @see PolylineCollection
   *
   */
  function Polyline(options, polylineCollection) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._show = defaultValue(options.show, true);
    this._width = defaultValue(options.width, 1.0);
    this._loop = defaultValue(options.loop, false);
    this._distanceDisplayCondition = options.distanceDisplayCondition;

    this._material = options.material;
    if (!defined(this._material)) {
      this._material = Material.fromType(Material.ColorType, {
        color: new Color(1.0, 1.0, 1.0, 1.0),
      });
    }

    var positions = options.positions;
    if (!defined(positions)) {
      positions = [];
    }

    this._positions = positions;
    this._actualPositions = arrayRemoveDuplicates(
      positions,
      Cartesian3.equalsEpsilon
    );

    if (this._loop && this._actualPositions.length > 2) {
      if (this._actualPositions === this._positions) {
        this._actualPositions = positions.slice();
      }
      this._actualPositions.push(Cartesian3.clone(this._actualPositions[0]));
    }

    this._length = this._actualPositions.length;
    this._id = options.id;

    var modelMatrix;
    if (defined(polylineCollection)) {
      modelMatrix = Matrix4.clone(polylineCollection.modelMatrix);
    }

    this._modelMatrix = modelMatrix;
    this._segments = PolylinePipeline.wrapLongitude(
      this._actualPositions,
      modelMatrix
    );

    this._actualLength = undefined;

    // eslint-disable-next-line no-use-before-define
    this._propertiesChanged = new Uint32Array(NUMBER_OF_PROPERTIES$1);
    this._polylineCollection = polylineCollection;
    this._dirty = false;
    this._pickId = undefined;
    this._boundingVolume = BoundingSphere.fromPoints(this._actualPositions);
    this._boundingVolumeWC = BoundingSphere.transform(
      this._boundingVolume,
      this._modelMatrix
    );
    this._boundingVolume2D = new BoundingSphere(); // modified in PolylineCollection
  }

  var POSITION_INDEX$2 = (Polyline.POSITION_INDEX = 0);
  var SHOW_INDEX$2 = (Polyline.SHOW_INDEX = 1);
  var WIDTH_INDEX = (Polyline.WIDTH_INDEX = 2);
  var MATERIAL_INDEX = (Polyline.MATERIAL_INDEX = 3);
  var POSITION_SIZE_INDEX = (Polyline.POSITION_SIZE_INDEX = 4);
  var DISTANCE_DISPLAY_CONDITION$1 = (Polyline.DISTANCE_DISPLAY_CONDITION = 5);
  var NUMBER_OF_PROPERTIES$1 = (Polyline.NUMBER_OF_PROPERTIES = 6);

  function makeDirty$1(polyline, propertyChanged) {
    ++polyline._propertiesChanged[propertyChanged];
    var polylineCollection = polyline._polylineCollection;
    if (defined(polylineCollection)) {
      polylineCollection._updatePolyline(polyline, propertyChanged);
      polyline._dirty = true;
    }
  }

  Object.defineProperties(Polyline.prototype, {
    /**
     * Determines if this polyline will be shown.  Use this to hide or show a polyline, instead
     * of removing it and re-adding it to the collection.
     * @memberof Polyline.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (value !== this._show) {
          this._show = value;
          makeDirty$1(this, SHOW_INDEX$2);
        }
      },
    },

    /**
     * Gets or sets the positions of the polyline.
     * @memberof Polyline.prototype
     * @type {Cartesian3[]}
     * @example
     * polyline.positions = Cesium.Cartesian3.fromDegreesArray([
     *     0.0, 0.0,
     *     10.0, 0.0,
     *     0.0, 20.0
     * ]);
     */
    positions: {
      get: function () {
        return this._positions;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var positions = arrayRemoveDuplicates(value, Cartesian3.equalsEpsilon);

        if (this._loop && positions.length > 2) {
          if (positions === value) {
            positions = value.slice();
          }
          positions.push(Cartesian3.clone(positions[0]));
        }

        if (
          this._actualPositions.length !== positions.length ||
          this._actualPositions.length !== this._length
        ) {
          makeDirty$1(this, POSITION_SIZE_INDEX);
        }

        this._positions = value;
        this._actualPositions = positions;
        this._length = positions.length;
        this._boundingVolume = BoundingSphere.fromPoints(
          this._actualPositions,
          this._boundingVolume
        );
        this._boundingVolumeWC = BoundingSphere.transform(
          this._boundingVolume,
          this._modelMatrix,
          this._boundingVolumeWC
        );
        makeDirty$1(this, POSITION_INDEX$2);

        this.update();
      },
    },

    /**
     * Gets or sets the surface appearance of the polyline.  This can be one of several built-in {@link Material} objects or a custom material, scripted with
     * {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}.
     * @memberof Polyline.prototype
     * @type {Material}
     */
    material: {
      get: function () {
        return this._material;
      },
      set: function (material) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(material)) {
          throw new DeveloperError("material is required.");
        }
        //>>includeEnd('debug');

        if (this._material !== material) {
          this._material = material;
          makeDirty$1(this, MATERIAL_INDEX);
        }
      },
    },

    /**
     * Gets or sets the width of the polyline.
     * @memberof Polyline.prototype
     * @type {Number}
     */
    width: {
      get: function () {
        return this._width;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug)
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var width = this._width;
        if (value !== width) {
          this._width = value;
          makeDirty$1(this, WIDTH_INDEX);
        }
      },
    },

    /**
     * Gets or sets whether a line segment will be added between the first and last polyline positions.
     * @memberof Polyline.prototype
     * @type {Boolean}
     */
    loop: {
      get: function () {
        return this._loop;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug)
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (value !== this._loop) {
          var positions = this._actualPositions;
          if (value) {
            if (
              positions.length > 2 &&
              !Cartesian3.equals(positions[0], positions[positions.length - 1])
            ) {
              if (positions.length === this._positions.length) {
                this._actualPositions = positions = this._positions.slice();
              }
              positions.push(Cartesian3.clone(positions[0]));
            }
          } else if (
            positions.length > 2 &&
            Cartesian3.equals(positions[0], positions[positions.length - 1])
          ) {
            if (positions.length - 1 === this._positions.length) {
              this._actualPositions = this._positions;
            } else {
              positions.pop();
            }
          }

          this._loop = value;
          makeDirty$1(this, POSITION_SIZE_INDEX);
        }
      },
    },

    /**
     * Gets or sets the user-defined value returned when the polyline is picked.
     * @memberof Polyline.prototype
     * @type {*}
     */
    id: {
      get: function () {
        return this._id;
      },
      set: function (value) {
        this._id = value;
        if (defined(this._pickId)) {
          this._pickId.object.id = value;
        }
      },
    },

    /**
     * @private
     */
    pickId: {
      get: function () {
        return this._pickId;
      },
    },

    /**
     * Gets the destruction status of this polyline
     * @memberof Polyline.prototype
     * @type {Boolean}
     * @default false
     * @private
     */
    isDestroyed: {
      get: function () {
        return !defined(this._polylineCollection);
      },
    },

    /**
     * Gets or sets the condition specifying at what distance from the camera that this polyline will be displayed.
     * @memberof Polyline.prototype
     * @type {DistanceDisplayCondition}
     * @default undefined
     */
    distanceDisplayCondition: {
      get: function () {
        return this._distanceDisplayCondition;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');
        if (
          !DistanceDisplayCondition.equals(value, this._distanceDisplayCondition)
        ) {
          this._distanceDisplayCondition = DistanceDisplayCondition.clone(
            value,
            this._distanceDisplayCondition
          );
          makeDirty$1(this, DISTANCE_DISPLAY_CONDITION$1);
        }
      },
    },
  });

  /**
   * @private
   */
  Polyline.prototype.update = function () {
    var modelMatrix = Matrix4.IDENTITY;
    if (defined(this._polylineCollection)) {
      modelMatrix = this._polylineCollection.modelMatrix;
    }

    var segmentPositionsLength = this._segments.positions.length;
    var segmentLengths = this._segments.lengths;

    var positionsChanged =
      this._propertiesChanged[POSITION_INDEX$2] > 0 ||
      this._propertiesChanged[POSITION_SIZE_INDEX] > 0;
    if (!Matrix4.equals(modelMatrix, this._modelMatrix) || positionsChanged) {
      this._segments = PolylinePipeline.wrapLongitude(
        this._actualPositions,
        modelMatrix
      );
      this._boundingVolumeWC = BoundingSphere.transform(
        this._boundingVolume,
        modelMatrix,
        this._boundingVolumeWC
      );
    }

    this._modelMatrix = Matrix4.clone(modelMatrix, this._modelMatrix);

    if (this._segments.positions.length !== segmentPositionsLength) {
      // number of positions changed
      makeDirty$1(this, POSITION_SIZE_INDEX);
    } else {
      var length = segmentLengths.length;
      for (var i = 0; i < length; ++i) {
        if (segmentLengths[i] !== this._segments.lengths[i]) {
          // indices changed
          makeDirty$1(this, POSITION_SIZE_INDEX);
          break;
        }
      }
    }
  };

  /**
   * @private
   */
  Polyline.prototype.getPickId = function (context) {
    if (!defined(this._pickId)) {
      this._pickId = context.createPickId({
        primitive: this,
        collection: this._polylineCollection,
        id: this._id,
      });
    }
    return this._pickId;
  };

  Polyline.prototype._clean = function () {
    this._dirty = false;
    var properties = this._propertiesChanged;
    for (var k = 0; k < NUMBER_OF_PROPERTIES$1 - 1; ++k) {
      properties[k] = 0;
    }
  };

  Polyline.prototype._destroy = function () {
    this._pickId = this._pickId && this._pickId.destroy();
    this._material = this._material && this._material.destroy();
    this._polylineCollection = undefined;
  };

  var SHOW_INDEX$3 = Polyline.SHOW_INDEX;
  var WIDTH_INDEX$1 = Polyline.WIDTH_INDEX;
  var POSITION_INDEX$3 = Polyline.POSITION_INDEX;
  var MATERIAL_INDEX$1 = Polyline.MATERIAL_INDEX;
  //POSITION_SIZE_INDEX is needed for when the polyline's position array changes size.
  //When it does, we need to recreate the indicesBuffer.
  var POSITION_SIZE_INDEX$1 = Polyline.POSITION_SIZE_INDEX;
  var DISTANCE_DISPLAY_CONDITION$2 = Polyline.DISTANCE_DISPLAY_CONDITION;
  var NUMBER_OF_PROPERTIES$2 = Polyline.NUMBER_OF_PROPERTIES;

  var attributeLocations$1 = {
    texCoordExpandAndBatchIndex: 0,
    position3DHigh: 1,
    position3DLow: 2,
    position2DHigh: 3,
    position2DLow: 4,
    prevPosition3DHigh: 5,
    prevPosition3DLow: 6,
    prevPosition2DHigh: 7,
    prevPosition2DLow: 8,
    nextPosition3DHigh: 9,
    nextPosition3DLow: 10,
    nextPosition2DHigh: 11,
    nextPosition2DLow: 12,
  };

  /**
   * A renderable collection of polylines.
   * <br /><br />
   * <div align="center">
   * <img src="Images/Polyline.png" width="400" height="300" /><br />
   * Example polylines
   * </div>
   * <br /><br />
   * Polylines are added and removed from the collection using {@link PolylineCollection#add}
   * and {@link PolylineCollection#remove}.
   *
   * @alias PolylineCollection
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms each polyline from model to world coordinates.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   *
   * @performance For best performance, prefer a few collections, each with many polylines, to
   * many collections with only a few polylines each.  Organize collections so that polylines
   * with the same update frequency are in the same collection, i.e., polylines that do not
   * change should be in one collection; polylines that change every frame should be in another
   * collection; and so on.
   *
   * @see PolylineCollection#add
   * @see PolylineCollection#remove
   * @see Polyline
   * @see LabelCollection
   *
   * @example
   * // Create a polyline collection with two polylines
   * var polylines = new Cesium.PolylineCollection();
   * polylines.add({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     -75.10, 39.57,
   *     -77.02, 38.53,
   *     -80.50, 35.14,
   *     -80.12, 25.46]),
   *   width : 2
   * });
   *
   * polylines.add({
   *   positions : Cesium.Cartesian3.fromDegreesArray([
   *     -73.10, 37.57,
   *     -75.02, 36.53,
   *     -78.50, 33.14,
   *     -78.12, 23.46]),
   *   width : 4
   * });
   */
  function PolylineCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The 4x4 transformation matrix that transforms each polyline in this collection from model to world coordinates.
     * When this is the identity matrix, the polylines are drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type {Matrix4}
     * @default {@link Matrix4.IDENTITY}
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = Matrix4.clone(Matrix4.IDENTITY);

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    this._opaqueRS = undefined;
    this._translucentRS = undefined;

    this._colorCommands = [];

    this._polylinesUpdated = false;
    this._polylinesRemoved = false;
    this._createVertexArray = false;
    this._propertiesChanged = new Uint32Array(NUMBER_OF_PROPERTIES$2);
    this._polylines = [];
    this._polylineBuckets = {};

    // The buffer usage is determined based on the usage of the attribute over time.
    this._positionBufferUsage = {
      bufferUsage: BufferUsage$1.STATIC_DRAW,
      frameCount: 0,
    };

    this._mode = undefined;

    this._polylinesToUpdate = [];
    this._vertexArrays = [];
    this._positionBuffer = undefined;
    this._texCoordExpandAndBatchIndexBuffer = undefined;

    this._batchTable = undefined;
    this._createBatchTable = false;

    // Only used by Vector3DTilePoints
    this._useHighlightColor = false;
    this._highlightColor = Color.clone(Color.WHITE);

    var that = this;
    this._uniformMap = {
      u_highlightColor: function () {
        return that._highlightColor;
      },
    };
  }

  Object.defineProperties(PolylineCollection.prototype, {
    /**
     * Returns the number of polylines in this collection.  This is commonly used with
     * {@link PolylineCollection#get} to iterate over all the polylines
     * in the collection.
     * @memberof PolylineCollection.prototype
     * @type {Number}
     */
    length: {
      get: function () {
        removePolylines(this);
        return this._polylines.length;
      },
    },
  });

  /**
       * Creates and adds a polyline with the specified initial properties to the collection.
       * The added polyline is returned so it can be modified or removed from the collection later.
       *
       * @param {Object}[options] A template describing the polyline's properties as shown in Example 1.
       * @returns {Polyline} The polyline that was added to the collection.
       *
       * @performance After calling <code>add</code>, {@link PolylineCollection#update} is called and
       * the collection's vertex buffer is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.
       * For best performance, add as many polylines as possible before calling <code>update</code>.
       *
       * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
       *
       *
       * @example
       * // Example 1:  Add a polyline, specifying all the default values.
       * var p = polylines.add({
       *   show : true,
       *   positions : ellipsoid.cartographicArrayToCartesianArray([
             Cesium.Cartographic.fromDegrees(-75.10, 39.57),
             Cesium.Cartographic.fromDegrees(-77.02, 38.53)]),
       *   width : 1
       * });
       *
       * @see PolylineCollection#remove
       * @see PolylineCollection#removeAll
       * @see PolylineCollection#update
       */
  PolylineCollection.prototype.add = function (options) {
    var p = new Polyline(options, this);
    p._index = this._polylines.length;
    this._polylines.push(p);
    this._createVertexArray = true;
    this._createBatchTable = true;
    return p;
  };

  /**
   * Removes a polyline from the collection.
   *
   * @param {Polyline} polyline The polyline to remove.
   * @returns {Boolean} <code>true</code> if the polyline was removed; <code>false</code> if the polyline was not found in the collection.
   *
   * @performance After calling <code>remove</code>, {@link PolylineCollection#update} is called and
   * the collection's vertex buffer is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.
   * For best performance, remove as many polylines as possible before calling <code>update</code>.
   * If you intend to temporarily hide a polyline, it is usually more efficient to call
   * {@link Polyline#show} instead of removing and re-adding the polyline.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * var p = polylines.add(...);
   * polylines.remove(p);  // Returns true
   *
   * @see PolylineCollection#add
   * @see PolylineCollection#removeAll
   * @see PolylineCollection#update
   * @see Polyline#show
   */
  PolylineCollection.prototype.remove = function (polyline) {
    if (this.contains(polyline)) {
      this._polylinesRemoved = true;
      this._createVertexArray = true;
      this._createBatchTable = true;
      if (defined(polyline._bucket)) {
        var bucket = polyline._bucket;
        bucket.shaderProgram =
          bucket.shaderProgram && bucket.shaderProgram.destroy();
      }
      polyline._destroy();
      return true;
    }

    return false;
  };

  /**
   * Removes all polylines from the collection.
   *
   * @performance <code>O(n)</code>.  It is more efficient to remove all the polylines
   * from a collection and then add new ones than to create a new collection entirely.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * polylines.add(...);
   * polylines.add(...);
   * polylines.removeAll();
   *
   * @see PolylineCollection#add
   * @see PolylineCollection#remove
   * @see PolylineCollection#update
   */
  PolylineCollection.prototype.removeAll = function () {
    releaseShaders(this);
    destroyPolylines(this);
    this._polylineBuckets = {};
    this._polylinesRemoved = false;
    this._polylines.length = 0;
    this._polylinesToUpdate.length = 0;
    this._createVertexArray = true;
  };

  /**
   * Determines if this collection contains the specified polyline.
   *
   * @param {Polyline} polyline The polyline to check for.
   * @returns {Boolean} true if this collection contains the polyline, false otherwise.
   *
   * @see PolylineCollection#get
   */
  PolylineCollection.prototype.contains = function (polyline) {
    return defined(polyline) && polyline._polylineCollection === this;
  };

  /**
   * Returns the polyline in the collection at the specified index.  Indices are zero-based
   * and increase as polylines are added.  Removing a polyline shifts all polylines after
   * it to the left, changing their indices.  This function is commonly used with
   * {@link PolylineCollection#length} to iterate over all the polylines
   * in the collection.
   *
   * @param {Number} index The zero-based index of the polyline.
   * @returns {Polyline} The polyline at the specified index.
   *
   * @performance If polylines were removed from the collection and
   * {@link PolylineCollection#update} was not called, an implicit <code>O(n)</code>
   * operation is performed.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * // Toggle the show property of every polyline in the collection
   * var len = polylines.length;
   * for (var i = 0; i < len; ++i) {
   *   var p = polylines.get(i);
   *   p.show = !p.show;
   * }
   *
   * @see PolylineCollection#length
   */
  PolylineCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    removePolylines(this);
    return this._polylines[index];
  };

  function createBatchTable$1(collection, context) {
    if (defined(collection._batchTable)) {
      collection._batchTable.destroy();
    }

    var attributes = [
      {
        functionName: "batchTable_getWidthAndShow",
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 2,
      },
      {
        functionName: "batchTable_getPickColor",
        componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        componentsPerAttribute: 4,
        normalize: true,
      },
      {
        functionName: "batchTable_getCenterHigh",
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 3,
      },
      {
        functionName: "batchTable_getCenterLowAndRadius",
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 4,
      },
      {
        functionName: "batchTable_getDistanceDisplayCondition",
        componentDatatype: ComponentDatatype$1.FLOAT,
        componentsPerAttribute: 2,
      },
    ];

    collection._batchTable = new BatchTable(
      context,
      attributes,
      collection._polylines.length
    );
  }

  var scratchUpdatePolylineEncodedCartesian = new EncodedCartesian3();
  var scratchUpdatePolylineCartesian4 = new Cartesian4();
  var scratchNearFarCartesian2 = new Cartesian2();

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {RuntimeError} Vertex texture fetch support is required to render primitives with per-instance attributes. The maximum number of vertex texture image units must be greater than zero.
   */
  PolylineCollection.prototype.update = function (frameState) {
    removePolylines(this);

    if (this._polylines.length === 0) {
      return;
    }

    updateMode$1(this, frameState);

    var context = frameState.context;
    var projection = frameState.mapProjection;
    var polyline;
    var properties = this._propertiesChanged;

    if (this._createBatchTable) {
      if (ContextLimits.maximumVertexTextureImageUnits === 0) {
        throw new RuntimeError(
          "Vertex texture fetch support is required to render polylines. The maximum number of vertex texture image units must be greater than zero."
        );
      }
      createBatchTable$1(this, context);
      this._createBatchTable = false;
    }

    if (this._createVertexArray || computeNewBuffersUsage(this)) {
      createVertexArrays$1(this, context, projection);
    } else if (this._polylinesUpdated) {
      // Polylines were modified, but no polylines were added or removed.
      var polylinesToUpdate = this._polylinesToUpdate;
      if (this._mode !== SceneMode$1.SCENE3D) {
        var updateLength = polylinesToUpdate.length;
        for (var i = 0; i < updateLength; ++i) {
          polyline = polylinesToUpdate[i];
          polyline.update();
        }
      }

      // if a polyline's positions size changes, we need to recreate the vertex arrays and vertex buffers because the indices will be different.
      // if a polyline's material changes, we need to recreate the VAOs and VBOs because they will be batched differently.
      if (properties[POSITION_SIZE_INDEX$1] || properties[MATERIAL_INDEX$1]) {
        createVertexArrays$1(this, context, projection);
      } else {
        var length = polylinesToUpdate.length;
        var polylineBuckets = this._polylineBuckets;
        for (var ii = 0; ii < length; ++ii) {
          polyline = polylinesToUpdate[ii];
          properties = polyline._propertiesChanged;
          var bucket = polyline._bucket;
          var index = 0;
          for (var x in polylineBuckets) {
            if (polylineBuckets.hasOwnProperty(x)) {
              if (polylineBuckets[x] === bucket) {
                if (properties[POSITION_INDEX$3]) {
                  bucket.writeUpdate(
                    index,
                    polyline,
                    this._positionBuffer,
                    projection
                  );
                }
                break;
              }
              index += polylineBuckets[x].lengthOfPositions;
            }
          }

          if (properties[SHOW_INDEX$3] || properties[WIDTH_INDEX$1]) {
            this._batchTable.setBatchedAttribute(
              polyline._index,
              0,
              new Cartesian2(polyline._width, polyline._show)
            );
          }

          if (this._batchTable.attributes.length > 2) {
            if (properties[POSITION_INDEX$3] || properties[POSITION_SIZE_INDEX$1]) {
              var boundingSphere =
                frameState.mode === SceneMode$1.SCENE2D
                  ? polyline._boundingVolume2D
                  : polyline._boundingVolumeWC;
              var encodedCenter = EncodedCartesian3.fromCartesian(
                boundingSphere.center,
                scratchUpdatePolylineEncodedCartesian
              );
              var low = Cartesian4.fromElements(
                encodedCenter.low.x,
                encodedCenter.low.y,
                encodedCenter.low.z,
                boundingSphere.radius,
                scratchUpdatePolylineCartesian4
              );
              this._batchTable.setBatchedAttribute(
                polyline._index,
                2,
                encodedCenter.high
              );
              this._batchTable.setBatchedAttribute(polyline._index, 3, low);
            }

            if (properties[DISTANCE_DISPLAY_CONDITION$2]) {
              var nearFarCartesian = scratchNearFarCartesian2;
              nearFarCartesian.x = 0.0;
              nearFarCartesian.y = Number.MAX_VALUE;

              var distanceDisplayCondition = polyline.distanceDisplayCondition;
              if (defined(distanceDisplayCondition)) {
                nearFarCartesian.x = distanceDisplayCondition.near;
                nearFarCartesian.y = distanceDisplayCondition.far;
              }

              this._batchTable.setBatchedAttribute(
                polyline._index,
                4,
                nearFarCartesian
              );
            }
          }

          polyline._clean();
        }
      }
      polylinesToUpdate.length = 0;
      this._polylinesUpdated = false;
    }

    properties = this._propertiesChanged;
    for (var k = 0; k < NUMBER_OF_PROPERTIES$2; ++k) {
      properties[k] = 0;
    }

    var modelMatrix = Matrix4.IDENTITY;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      modelMatrix = this.modelMatrix;
    }

    var pass = frameState.passes;
    var useDepthTest = frameState.morphTime !== 0.0;

    if (
      !defined(this._opaqueRS) ||
      this._opaqueRS.depthTest.enabled !== useDepthTest
    ) {
      this._opaqueRS = RenderState.fromCache({
        depthMask: useDepthTest,
        depthTest: {
          enabled: useDepthTest,
        },
      });
    }

    if (
      !defined(this._translucentRS) ||
      this._translucentRS.depthTest.enabled !== useDepthTest
    ) {
      this._translucentRS = RenderState.fromCache({
        blending: BlendingState$1.ALPHA_BLEND,
        depthMask: !useDepthTest,
        depthTest: {
          enabled: useDepthTest,
        },
      });
    }

    this._batchTable.update(frameState);

    if (pass.render || pass.pick) {
      var colorList = this._colorCommands;
      createCommandLists(this, frameState, colorList, modelMatrix);
    }
  };

  var boundingSphereScratch = new BoundingSphere();
  var boundingSphereScratch2 = new BoundingSphere();

  function createCommandLists(
    polylineCollection,
    frameState,
    commands,
    modelMatrix
  ) {
    var context = frameState.context;
    var commandList = frameState.commandList;

    var commandsLength = commands.length;
    var commandIndex = 0;
    var cloneBoundingSphere = true;

    var vertexArrays = polylineCollection._vertexArrays;
    var debugShowBoundingVolume = polylineCollection.debugShowBoundingVolume;

    var batchTable = polylineCollection._batchTable;
    var uniformCallback = batchTable.getUniformMapCallback();

    var length = vertexArrays.length;
    for (var m = 0; m < length; ++m) {
      var va = vertexArrays[m];
      var buckets = va.buckets;
      var bucketLength = buckets.length;

      for (var n = 0; n < bucketLength; ++n) {
        var bucketLocator = buckets[n];

        var offset = bucketLocator.offset;
        var sp = bucketLocator.bucket.shaderProgram;

        var polylines = bucketLocator.bucket.polylines;
        var polylineLength = polylines.length;
        var currentId;
        var currentMaterial;
        var count = 0;
        var command;
        var uniformMap;

        for (var s = 0; s < polylineLength; ++s) {
          var polyline = polylines[s];
          var mId = createMaterialId(polyline._material);
          if (mId !== currentId) {
            if (defined(currentId) && count > 0) {
              var translucent = currentMaterial.isTranslucent();

              if (commandIndex >= commandsLength) {
                command = new DrawCommand({
                  owner: polylineCollection,
                });
                commands.push(command);
              } else {
                command = commands[commandIndex];
              }

              ++commandIndex;

              uniformMap = combine(
                uniformCallback(currentMaterial._uniforms),
                polylineCollection._uniformMap
              );

              command.boundingVolume = BoundingSphere.clone(
                boundingSphereScratch,
                command.boundingVolume
              );
              command.modelMatrix = modelMatrix;
              command.shaderProgram = sp;
              command.vertexArray = va.va;
              command.renderState = translucent
                ? polylineCollection._translucentRS
                : polylineCollection._opaqueRS;
              command.pass = translucent ? Pass$1.TRANSLUCENT : Pass$1.OPAQUE;
              command.debugShowBoundingVolume = debugShowBoundingVolume;
              command.pickId = "v_pickColor";

              command.uniformMap = uniformMap;
              command.count = count;
              command.offset = offset;

              offset += count;
              count = 0;
              cloneBoundingSphere = true;

              commandList.push(command);
            }

            currentMaterial = polyline._material;
            currentMaterial.update(context);
            currentId = mId;
          }

          var locators = polyline._locatorBuckets;
          var locatorLength = locators.length;
          for (var t = 0; t < locatorLength; ++t) {
            var locator = locators[t];
            if (locator.locator === bucketLocator) {
              count += locator.count;
            }
          }

          var boundingVolume;
          if (frameState.mode === SceneMode$1.SCENE3D) {
            boundingVolume = polyline._boundingVolumeWC;
          } else if (frameState.mode === SceneMode$1.COLUMBUS_VIEW) {
            boundingVolume = polyline._boundingVolume2D;
          } else if (frameState.mode === SceneMode$1.SCENE2D) {
            if (defined(polyline._boundingVolume2D)) {
              boundingVolume = BoundingSphere.clone(
                polyline._boundingVolume2D,
                boundingSphereScratch2
              );
              boundingVolume.center.x = 0.0;
            }
          } else if (
            defined(polyline._boundingVolumeWC) &&
            defined(polyline._boundingVolume2D)
          ) {
            boundingVolume = BoundingSphere.union(
              polyline._boundingVolumeWC,
              polyline._boundingVolume2D,
              boundingSphereScratch2
            );
          }

          if (cloneBoundingSphere) {
            cloneBoundingSphere = false;
            BoundingSphere.clone(boundingVolume, boundingSphereScratch);
          } else {
            BoundingSphere.union(
              boundingVolume,
              boundingSphereScratch,
              boundingSphereScratch
            );
          }
        }

        if (defined(currentId) && count > 0) {
          if (commandIndex >= commandsLength) {
            command = new DrawCommand({
              owner: polylineCollection,
            });
            commands.push(command);
          } else {
            command = commands[commandIndex];
          }

          ++commandIndex;

          uniformMap = combine(
            uniformCallback(currentMaterial._uniforms),
            polylineCollection._uniformMap
          );

          command.boundingVolume = BoundingSphere.clone(
            boundingSphereScratch,
            command.boundingVolume
          );
          command.modelMatrix = modelMatrix;
          command.shaderProgram = sp;
          command.vertexArray = va.va;
          command.renderState = currentMaterial.isTranslucent()
            ? polylineCollection._translucentRS
            : polylineCollection._opaqueRS;
          command.pass = currentMaterial.isTranslucent()
            ? Pass$1.TRANSLUCENT
            : Pass$1.OPAQUE;
          command.debugShowBoundingVolume = debugShowBoundingVolume;
          command.pickId = "v_pickColor";

          command.uniformMap = uniformMap;
          command.count = count;
          command.offset = offset;

          cloneBoundingSphere = true;

          commandList.push(command);
        }

        currentId = undefined;
      }
    }

    commands.length = commandIndex;
  }

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PolylineCollection#destroy
   */
  PolylineCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * polylines = polylines && polylines.destroy();
   *
   * @see PolylineCollection#isDestroyed
   */
  PolylineCollection.prototype.destroy = function () {
    destroyVertexArrays(this);
    releaseShaders(this);
    destroyPolylines(this);
    this._batchTable = this._batchTable && this._batchTable.destroy();
    return destroyObject(this);
  };

  function computeNewBuffersUsage(collection) {
    var usageChanged = false;
    var properties = collection._propertiesChanged;
    var bufferUsage = collection._positionBufferUsage;
    if (properties[POSITION_INDEX$3]) {
      if (bufferUsage.bufferUsage !== BufferUsage$1.STREAM_DRAW) {
        usageChanged = true;
        bufferUsage.bufferUsage = BufferUsage$1.STREAM_DRAW;
        bufferUsage.frameCount = 100;
      } else {
        bufferUsage.frameCount = 100;
      }
    } else if (bufferUsage.bufferUsage !== BufferUsage$1.STATIC_DRAW) {
      if (bufferUsage.frameCount === 0) {
        usageChanged = true;
        bufferUsage.bufferUsage = BufferUsage$1.STATIC_DRAW;
      } else {
        bufferUsage.frameCount--;
      }
    }

    return usageChanged;
  }

  var emptyVertexBuffer = [0.0, 0.0, 0.0];

  function createVertexArrays$1(collection, context, projection) {
    collection._createVertexArray = false;
    releaseShaders(collection);
    destroyVertexArrays(collection);
    sortPolylinesIntoBuckets(collection);

    //stores all of the individual indices arrays.
    var totalIndices = [[]];
    var indices = totalIndices[0];

    var batchTable = collection._batchTable;
    var useHighlightColor = collection._useHighlightColor;

    //used to determine the vertexBuffer offset if the indicesArray goes over 64k.
    //if it's the same polyline while it goes over 64k, the offset needs to backtrack componentsPerAttribute * componentDatatype bytes
    //so that the polyline looks contiguous.
    //if the polyline ends at the 64k mark, then the offset is just 64k * componentsPerAttribute * componentDatatype
    var vertexBufferOffset = [0];
    var offset = 0;
    var vertexArrayBuckets = [[]];
    var totalLength = 0;
    var polylineBuckets = collection._polylineBuckets;
    var x;
    var bucket;
    for (x in polylineBuckets) {
      if (polylineBuckets.hasOwnProperty(x)) {
        bucket = polylineBuckets[x];
        bucket.updateShader(context, batchTable, useHighlightColor);
        totalLength += bucket.lengthOfPositions;
      }
    }

    if (totalLength > 0) {
      var mode = collection._mode;

      var positionArray = new Float32Array(6 * totalLength * 3);
      var texCoordExpandAndBatchIndexArray = new Float32Array(totalLength * 4);
      var position3DArray;

      var positionIndex = 0;
      var colorIndex = 0;
      var texCoordExpandAndBatchIndexIndex = 0;
      for (x in polylineBuckets) {
        if (polylineBuckets.hasOwnProperty(x)) {
          bucket = polylineBuckets[x];
          bucket.write(
            positionArray,
            texCoordExpandAndBatchIndexArray,
            positionIndex,
            colorIndex,
            texCoordExpandAndBatchIndexIndex,
            batchTable,
            context,
            projection
          );

          if (mode === SceneMode$1.MORPHING) {
            if (!defined(position3DArray)) {
              position3DArray = new Float32Array(6 * totalLength * 3);
            }
            bucket.writeForMorph(position3DArray, positionIndex);
          }

          var bucketLength = bucket.lengthOfPositions;
          positionIndex += 6 * bucketLength * 3;
          colorIndex += bucketLength * 4;
          texCoordExpandAndBatchIndexIndex += bucketLength * 4;
          offset = bucket.updateIndices(
            totalIndices,
            vertexBufferOffset,
            vertexArrayBuckets,
            offset
          );
        }
      }

      var positionBufferUsage = collection._positionBufferUsage.bufferUsage;
      var texCoordExpandAndBatchIndexBufferUsage = BufferUsage$1.STATIC_DRAW;

      collection._positionBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: positionArray,
        usage: positionBufferUsage,
      });
      var position3DBuffer;
      if (defined(position3DArray)) {
        position3DBuffer = Buffer$1.createVertexBuffer({
          context: context,
          typedArray: position3DArray,
          usage: positionBufferUsage,
        });
      }
      collection._texCoordExpandAndBatchIndexBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: texCoordExpandAndBatchIndexArray,
        usage: texCoordExpandAndBatchIndexBufferUsage,
      });

      var positionSizeInBytes = 3 * Float32Array.BYTES_PER_ELEMENT;
      var texCoordExpandAndBatchIndexSizeInBytes =
        4 * Float32Array.BYTES_PER_ELEMENT;

      var vbo = 0;
      var numberOfIndicesArrays = totalIndices.length;
      for (var k = 0; k < numberOfIndicesArrays; ++k) {
        indices = totalIndices[k];

        if (indices.length > 0) {
          var indicesArray = new Uint16Array(indices);
          var indexBuffer = Buffer$1.createIndexBuffer({
            context: context,
            typedArray: indicesArray,
            usage: BufferUsage$1.STATIC_DRAW,
            indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
          });

          vbo += vertexBufferOffset[k];

          var positionHighOffset =
            6 *
            (k * (positionSizeInBytes * CesiumMath.SIXTY_FOUR_KILOBYTES) -
              vbo * positionSizeInBytes); //componentsPerAttribute(3) * componentDatatype(4)
          var positionLowOffset = positionSizeInBytes + positionHighOffset;
          var prevPositionHighOffset = positionSizeInBytes + positionLowOffset;
          var prevPositionLowOffset =
            positionSizeInBytes + prevPositionHighOffset;
          var nextPositionHighOffset =
            positionSizeInBytes + prevPositionLowOffset;
          var nextPositionLowOffset =
            positionSizeInBytes + nextPositionHighOffset;
          var vertexTexCoordExpandAndBatchIndexBufferOffset =
            k *
              (texCoordExpandAndBatchIndexSizeInBytes *
                CesiumMath.SIXTY_FOUR_KILOBYTES) -
            vbo * texCoordExpandAndBatchIndexSizeInBytes;

          var attributes = [
            {
              index: attributeLocations$1.position3DHigh,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: positionHighOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.position3DLow,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: positionLowOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.position2DHigh,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: positionHighOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.position2DLow,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: positionLowOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.prevPosition3DHigh,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: prevPositionHighOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.prevPosition3DLow,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: prevPositionLowOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.prevPosition2DHigh,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: prevPositionHighOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.prevPosition2DLow,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: prevPositionLowOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.nextPosition3DHigh,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: nextPositionHighOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.nextPosition3DLow,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: nextPositionLowOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.nextPosition2DHigh,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: nextPositionHighOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.nextPosition2DLow,
              componentsPerAttribute: 3,
              componentDatatype: ComponentDatatype$1.FLOAT,
              offsetInBytes: nextPositionLowOffset,
              strideInBytes: 6 * positionSizeInBytes,
            },
            {
              index: attributeLocations$1.texCoordExpandAndBatchIndex,
              componentsPerAttribute: 4,
              componentDatatype: ComponentDatatype$1.FLOAT,
              vertexBuffer: collection._texCoordExpandAndBatchIndexBuffer,
              offsetInBytes: vertexTexCoordExpandAndBatchIndexBufferOffset,
            },
          ];

          var buffer3D;
          var bufferProperty3D;
          var buffer2D;
          var bufferProperty2D;

          if (mode === SceneMode$1.SCENE3D) {
            buffer3D = collection._positionBuffer;
            bufferProperty3D = "vertexBuffer";
            buffer2D = emptyVertexBuffer;
            bufferProperty2D = "value";
          } else if (
            mode === SceneMode$1.SCENE2D ||
            mode === SceneMode$1.COLUMBUS_VIEW
          ) {
            buffer3D = emptyVertexBuffer;
            bufferProperty3D = "value";
            buffer2D = collection._positionBuffer;
            bufferProperty2D = "vertexBuffer";
          } else {
            buffer3D = position3DBuffer;
            bufferProperty3D = "vertexBuffer";
            buffer2D = collection._positionBuffer;
            bufferProperty2D = "vertexBuffer";
          }

          attributes[0][bufferProperty3D] = buffer3D;
          attributes[1][bufferProperty3D] = buffer3D;
          attributes[2][bufferProperty2D] = buffer2D;
          attributes[3][bufferProperty2D] = buffer2D;
          attributes[4][bufferProperty3D] = buffer3D;
          attributes[5][bufferProperty3D] = buffer3D;
          attributes[6][bufferProperty2D] = buffer2D;
          attributes[7][bufferProperty2D] = buffer2D;
          attributes[8][bufferProperty3D] = buffer3D;
          attributes[9][bufferProperty3D] = buffer3D;
          attributes[10][bufferProperty2D] = buffer2D;
          attributes[11][bufferProperty2D] = buffer2D;

          var va = new VertexArray({
            context: context,
            attributes: attributes,
            indexBuffer: indexBuffer,
          });
          collection._vertexArrays.push({
            va: va,
            buckets: vertexArrayBuckets[k],
          });
        }
      }
    }
  }

  function replacer(key, value) {
    if (value instanceof Texture) {
      return value.id;
    }

    return value;
  }

  var scratchUniformArray$1 = [];
  function createMaterialId(material) {
    var uniforms = Material._uniformList[material.type];
    var length = uniforms.length;
    scratchUniformArray$1.length = 2.0 * length;

    var index = 0;
    for (var i = 0; i < length; ++i) {
      var uniform = uniforms[i];
      scratchUniformArray$1[index] = uniform;
      scratchUniformArray$1[index + 1] = material._uniforms[uniform]();
      index += 2;
    }

    return material.type + ":" + JSON.stringify(scratchUniformArray$1, replacer);
  }

  function sortPolylinesIntoBuckets(collection) {
    var mode = collection._mode;
    var modelMatrix = collection._modelMatrix;

    var polylineBuckets = (collection._polylineBuckets = {});
    var polylines = collection._polylines;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      var p = polylines[i];
      if (p._actualPositions.length > 1) {
        p.update();
        var material = p.material;
        var value = polylineBuckets[material.type];
        if (!defined(value)) {
          value = polylineBuckets[material.type] = new PolylineBucket(
            material,
            mode,
            modelMatrix
          );
        }
        value.addPolyline(p);
      }
    }
  }

  function updateMode$1(collection, frameState) {
    var mode = frameState.mode;

    if (
      collection._mode !== mode ||
      !Matrix4.equals(collection._modelMatrix, collection.modelMatrix)
    ) {
      collection._mode = mode;
      collection._modelMatrix = Matrix4.clone(collection.modelMatrix);
      collection._createVertexArray = true;
    }
  }

  function removePolylines(collection) {
    if (collection._polylinesRemoved) {
      collection._polylinesRemoved = false;
      var definedPolylines = [];
      var definedPolylinesToUpdate = [];
      var polyIndex = 0;
      var polyline;

      var length = collection._polylines.length;
      for (var i = 0; i < length; ++i) {
        polyline = collection._polylines[i];
        if (!polyline.isDestroyed) {
          polyline._index = polyIndex++;
          definedPolylinesToUpdate.push(polyline);
          definedPolylines.push(polyline);
        }
      }

      collection._polylines = definedPolylines;
      collection._polylinesToUpdate = definedPolylinesToUpdate;
    }
  }

  function releaseShaders(collection) {
    var polylines = collection._polylines;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      if (!polylines[i].isDestroyed) {
        var bucket = polylines[i]._bucket;
        if (defined(bucket)) {
          bucket.shaderProgram =
            bucket.shaderProgram && bucket.shaderProgram.destroy();
        }
      }
    }
  }

  function destroyVertexArrays(collection) {
    var length = collection._vertexArrays.length;
    for (var t = 0; t < length; ++t) {
      collection._vertexArrays[t].va.destroy();
    }
    collection._vertexArrays.length = 0;
  }

  PolylineCollection.prototype._updatePolyline = function (
    polyline,
    propertyChanged
  ) {
    this._polylinesUpdated = true;
    if (!polyline._dirty) {
      this._polylinesToUpdate.push(polyline);
    }
    ++this._propertiesChanged[propertyChanged];
  };

  function destroyPolylines(collection) {
    var polylines = collection._polylines;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      if (!polylines[i].isDestroyed) {
        polylines[i]._destroy();
      }
    }
  }

  function VertexArrayBucketLocator(count, offset, bucket) {
    this.count = count;
    this.offset = offset;
    this.bucket = bucket;
  }

  function PolylineBucket(material, mode, modelMatrix) {
    this.polylines = [];
    this.lengthOfPositions = 0;
    this.material = material;
    this.shaderProgram = undefined;
    this.mode = mode;
    this.modelMatrix = modelMatrix;
  }

  PolylineBucket.prototype.addPolyline = function (p) {
    var polylines = this.polylines;
    polylines.push(p);
    p._actualLength = this.getPolylinePositionsLength(p);
    this.lengthOfPositions += p._actualLength;
    p._bucket = this;
  };

  PolylineBucket.prototype.updateShader = function (
    context,
    batchTable,
    useHighlightColor
  ) {
    if (defined(this.shaderProgram)) {
      return;
    }

    var defines = ["DISTANCE_DISPLAY_CONDITION"];
    if (useHighlightColor) {
      defines.push("VECTOR_TILE");
    }

    // Check for use of v_polylineAngle in material shader
    if (
      this.material.shaderSource.search(/varying\s+float\s+v_polylineAngle;/g) !==
      -1
    ) {
      defines.push("POLYLINE_DASH");
    }

    if (!FeatureDetection.isInternetExplorer()) {
      defines.push("CLIP_POLYLINE");
    }

    var fs = new ShaderSource({
      defines: defines,
      sources: [
        "varying vec4 v_pickColor;\n",
        this.material.shaderSource,
        PolylineFS,
      ],
    });

    var vsSource = batchTable.getVertexShaderCallback()(PolylineVS);
    var vs = new ShaderSource({
      defines: defines,
      sources: [PolylineCommon, vsSource],
    });

    this.shaderProgram = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations$1,
    });
  };

  function intersectsIDL(polyline) {
    return (
      Cartesian3.dot(Cartesian3.UNIT_X, polyline._boundingVolume.center) < 0 ||
      polyline._boundingVolume.intersectPlane(Plane.ORIGIN_ZX_PLANE) ===
        Intersect$1.INTERSECTING
    );
  }

  PolylineBucket.prototype.getPolylinePositionsLength = function (polyline) {
    var length;
    if (this.mode === SceneMode$1.SCENE3D || !intersectsIDL(polyline)) {
      length = polyline._actualPositions.length;
      return length * 4.0 - 4.0;
    }

    var count = 0;
    var segmentLengths = polyline._segments.lengths;
    length = segmentLengths.length;
    for (var i = 0; i < length; ++i) {
      count += segmentLengths[i] * 4.0 - 4.0;
    }

    return count;
  };

  var scratchWritePosition = new Cartesian3();
  var scratchWritePrevPosition = new Cartesian3();
  var scratchWriteNextPosition = new Cartesian3();
  var scratchWriteVector = new Cartesian3();
  var scratchPickColorCartesian = new Cartesian4();
  var scratchWidthShowCartesian = new Cartesian2();

  PolylineBucket.prototype.write = function (
    positionArray,
    texCoordExpandAndBatchIndexArray,
    positionIndex,
    colorIndex,
    texCoordExpandAndBatchIndexIndex,
    batchTable,
    context,
    projection
  ) {
    var mode = this.mode;
    var maxLon = projection.ellipsoid.maximumRadius * CesiumMath.PI;

    var polylines = this.polylines;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      var polyline = polylines[i];
      var width = polyline.width;
      var show = polyline.show && width > 0.0;
      var polylineBatchIndex = polyline._index;
      var segments = this.getSegments(polyline, projection);
      var positions = segments.positions;
      var lengths = segments.lengths;
      var positionsLength = positions.length;

      var pickColor = polyline.getPickId(context).color;

      var segmentIndex = 0;
      var count = 0;
      var position;

      for (var j = 0; j < positionsLength; ++j) {
        if (j === 0) {
          if (polyline._loop) {
            position = positions[positionsLength - 2];
          } else {
            position = scratchWriteVector;
            Cartesian3.subtract(positions[0], positions[1], position);
            Cartesian3.add(positions[0], position, position);
          }
        } else {
          position = positions[j - 1];
        }

        Cartesian3.clone(position, scratchWritePrevPosition);
        Cartesian3.clone(positions[j], scratchWritePosition);

        if (j === positionsLength - 1) {
          if (polyline._loop) {
            position = positions[1];
          } else {
            position = scratchWriteVector;
            Cartesian3.subtract(
              positions[positionsLength - 1],
              positions[positionsLength - 2],
              position
            );
            Cartesian3.add(positions[positionsLength - 1], position, position);
          }
        } else {
          position = positions[j + 1];
        }

        Cartesian3.clone(position, scratchWriteNextPosition);

        var segmentLength = lengths[segmentIndex];
        if (j === count + segmentLength) {
          count += segmentLength;
          ++segmentIndex;
        }

        var segmentStart = j - count === 0;
        var segmentEnd = j === count + lengths[segmentIndex] - 1;

        if (mode === SceneMode$1.SCENE2D) {
          scratchWritePrevPosition.z = 0.0;
          scratchWritePosition.z = 0.0;
          scratchWriteNextPosition.z = 0.0;
        }

        if (mode === SceneMode$1.SCENE2D || mode === SceneMode$1.MORPHING) {
          if (
            (segmentStart || segmentEnd) &&
            maxLon - Math.abs(scratchWritePosition.x) < 1.0
          ) {
            if (
              (scratchWritePosition.x < 0.0 &&
                scratchWritePrevPosition.x > 0.0) ||
              (scratchWritePosition.x > 0.0 && scratchWritePrevPosition.x < 0.0)
            ) {
              Cartesian3.clone(scratchWritePosition, scratchWritePrevPosition);
            }

            if (
              (scratchWritePosition.x < 0.0 &&
                scratchWriteNextPosition.x > 0.0) ||
              (scratchWritePosition.x > 0.0 && scratchWriteNextPosition.x < 0.0)
            ) {
              Cartesian3.clone(scratchWritePosition, scratchWriteNextPosition);
            }
          }
        }

        var startK = segmentStart ? 2 : 0;
        var endK = segmentEnd ? 2 : 4;

        for (var k = startK; k < endK; ++k) {
          EncodedCartesian3.writeElements(
            scratchWritePosition,
            positionArray,
            positionIndex
          );
          EncodedCartesian3.writeElements(
            scratchWritePrevPosition,
            positionArray,
            positionIndex + 6
          );
          EncodedCartesian3.writeElements(
            scratchWriteNextPosition,
            positionArray,
            positionIndex + 12
          );

          var direction = k - 2 < 0 ? -1.0 : 1.0;
          texCoordExpandAndBatchIndexArray[texCoordExpandAndBatchIndexIndex] =
            j / (positionsLength - 1); // s tex coord
          texCoordExpandAndBatchIndexArray[texCoordExpandAndBatchIndexIndex + 1] =
            2 * (k % 2) - 1; // expand direction
          texCoordExpandAndBatchIndexArray[
            texCoordExpandAndBatchIndexIndex + 2
          ] = direction;
          texCoordExpandAndBatchIndexArray[
            texCoordExpandAndBatchIndexIndex + 3
          ] = polylineBatchIndex;

          positionIndex += 6 * 3;
          texCoordExpandAndBatchIndexIndex += 4;
        }
      }

      var colorCartesian = scratchPickColorCartesian;
      colorCartesian.x = Color.floatToByte(pickColor.red);
      colorCartesian.y = Color.floatToByte(pickColor.green);
      colorCartesian.z = Color.floatToByte(pickColor.blue);
      colorCartesian.w = Color.floatToByte(pickColor.alpha);

      var widthShowCartesian = scratchWidthShowCartesian;
      widthShowCartesian.x = width;
      widthShowCartesian.y = show ? 1.0 : 0.0;

      var boundingSphere =
        mode === SceneMode$1.SCENE2D
          ? polyline._boundingVolume2D
          : polyline._boundingVolumeWC;
      var encodedCenter = EncodedCartesian3.fromCartesian(
        boundingSphere.center,
        scratchUpdatePolylineEncodedCartesian
      );
      var high = encodedCenter.high;
      var low = Cartesian4.fromElements(
        encodedCenter.low.x,
        encodedCenter.low.y,
        encodedCenter.low.z,
        boundingSphere.radius,
        scratchUpdatePolylineCartesian4
      );

      var nearFarCartesian = scratchNearFarCartesian2;
      nearFarCartesian.x = 0.0;
      nearFarCartesian.y = Number.MAX_VALUE;

      var distanceDisplayCondition = polyline.distanceDisplayCondition;
      if (defined(distanceDisplayCondition)) {
        nearFarCartesian.x = distanceDisplayCondition.near;
        nearFarCartesian.y = distanceDisplayCondition.far;
      }

      batchTable.setBatchedAttribute(polylineBatchIndex, 0, widthShowCartesian);
      batchTable.setBatchedAttribute(polylineBatchIndex, 1, colorCartesian);

      if (batchTable.attributes.length > 2) {
        batchTable.setBatchedAttribute(polylineBatchIndex, 2, high);
        batchTable.setBatchedAttribute(polylineBatchIndex, 3, low);
        batchTable.setBatchedAttribute(polylineBatchIndex, 4, nearFarCartesian);
      }
    }
  };

  var morphPositionScratch = new Cartesian3();
  var morphPrevPositionScratch = new Cartesian3();
  var morphNextPositionScratch = new Cartesian3();
  var morphVectorScratch = new Cartesian3();

  PolylineBucket.prototype.writeForMorph = function (
    positionArray,
    positionIndex
  ) {
    var modelMatrix = this.modelMatrix;
    var polylines = this.polylines;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      var polyline = polylines[i];
      var positions = polyline._segments.positions;
      var lengths = polyline._segments.lengths;
      var positionsLength = positions.length;

      var segmentIndex = 0;
      var count = 0;

      for (var j = 0; j < positionsLength; ++j) {
        var prevPosition;
        if (j === 0) {
          if (polyline._loop) {
            prevPosition = positions[positionsLength - 2];
          } else {
            prevPosition = morphVectorScratch;
            Cartesian3.subtract(positions[0], positions[1], prevPosition);
            Cartesian3.add(positions[0], prevPosition, prevPosition);
          }
        } else {
          prevPosition = positions[j - 1];
        }

        prevPosition = Matrix4.multiplyByPoint(
          modelMatrix,
          prevPosition,
          morphPrevPositionScratch
        );

        var position = Matrix4.multiplyByPoint(
          modelMatrix,
          positions[j],
          morphPositionScratch
        );

        var nextPosition;
        if (j === positionsLength - 1) {
          if (polyline._loop) {
            nextPosition = positions[1];
          } else {
            nextPosition = morphVectorScratch;
            Cartesian3.subtract(
              positions[positionsLength - 1],
              positions[positionsLength - 2],
              nextPosition
            );
            Cartesian3.add(
              positions[positionsLength - 1],
              nextPosition,
              nextPosition
            );
          }
        } else {
          nextPosition = positions[j + 1];
        }

        nextPosition = Matrix4.multiplyByPoint(
          modelMatrix,
          nextPosition,
          morphNextPositionScratch
        );

        var segmentLength = lengths[segmentIndex];
        if (j === count + segmentLength) {
          count += segmentLength;
          ++segmentIndex;
        }

        var segmentStart = j - count === 0;
        var segmentEnd = j === count + lengths[segmentIndex] - 1;

        var startK = segmentStart ? 2 : 0;
        var endK = segmentEnd ? 2 : 4;

        for (var k = startK; k < endK; ++k) {
          EncodedCartesian3.writeElements(position, positionArray, positionIndex);
          EncodedCartesian3.writeElements(
            prevPosition,
            positionArray,
            positionIndex + 6
          );
          EncodedCartesian3.writeElements(
            nextPosition,
            positionArray,
            positionIndex + 12
          );

          positionIndex += 6 * 3;
        }
      }
    }
  };

  var scratchSegmentLengths = new Array(1);

  PolylineBucket.prototype.updateIndices = function (
    totalIndices,
    vertexBufferOffset,
    vertexArrayBuckets,
    offset
  ) {
    var vaCount = vertexArrayBuckets.length - 1;
    var bucketLocator = new VertexArrayBucketLocator(0, offset, this);
    vertexArrayBuckets[vaCount].push(bucketLocator);
    var count = 0;
    var indices = totalIndices[totalIndices.length - 1];
    var indicesCount = 0;
    if (indices.length > 0) {
      indicesCount = indices[indices.length - 1] + 1;
    }
    var polylines = this.polylines;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      var polyline = polylines[i];
      polyline._locatorBuckets = [];

      var segments;
      if (this.mode === SceneMode$1.SCENE3D) {
        segments = scratchSegmentLengths;
        var positionsLength = polyline._actualPositions.length;
        if (positionsLength > 0) {
          segments[0] = positionsLength;
        } else {
          continue;
        }
      } else {
        segments = polyline._segments.lengths;
      }

      var numberOfSegments = segments.length;
      if (numberOfSegments > 0) {
        var segmentIndexCount = 0;
        for (var j = 0; j < numberOfSegments; ++j) {
          var segmentLength = segments[j] - 1.0;
          for (var k = 0; k < segmentLength; ++k) {
            if (indicesCount + 4 > CesiumMath.SIXTY_FOUR_KILOBYTES) {
              polyline._locatorBuckets.push({
                locator: bucketLocator,
                count: segmentIndexCount,
              });
              segmentIndexCount = 0;
              vertexBufferOffset.push(4);
              indices = [];
              totalIndices.push(indices);
              indicesCount = 0;
              bucketLocator.count = count;
              count = 0;
              offset = 0;
              bucketLocator = new VertexArrayBucketLocator(0, 0, this);
              vertexArrayBuckets[++vaCount] = [bucketLocator];
            }

            indices.push(indicesCount, indicesCount + 2, indicesCount + 1);
            indices.push(indicesCount + 1, indicesCount + 2, indicesCount + 3);

            segmentIndexCount += 6;
            count += 6;
            offset += 6;
            indicesCount += 4;
          }
        }

        polyline._locatorBuckets.push({
          locator: bucketLocator,
          count: segmentIndexCount,
        });

        if (indicesCount + 4 > CesiumMath.SIXTY_FOUR_KILOBYTES) {
          vertexBufferOffset.push(0);
          indices = [];
          totalIndices.push(indices);
          indicesCount = 0;
          bucketLocator.count = count;
          offset = 0;
          count = 0;
          bucketLocator = new VertexArrayBucketLocator(0, 0, this);
          vertexArrayBuckets[++vaCount] = [bucketLocator];
        }
      }
      polyline._clean();
    }
    bucketLocator.count = count;
    return offset;
  };

  PolylineBucket.prototype.getPolylineStartIndex = function (polyline) {
    var polylines = this.polylines;
    var positionIndex = 0;
    var length = polylines.length;
    for (var i = 0; i < length; ++i) {
      var p = polylines[i];
      if (p === polyline) {
        break;
      }
      positionIndex += p._actualLength;
    }
    return positionIndex;
  };

  var scratchSegments = {
    positions: undefined,
    lengths: undefined,
  };
  var scratchLengths = new Array(1);
  var pscratch = new Cartesian3();
  var scratchCartographic$6 = new Cartographic();

  PolylineBucket.prototype.getSegments = function (polyline, projection) {
    var positions = polyline._actualPositions;

    if (this.mode === SceneMode$1.SCENE3D) {
      scratchLengths[0] = positions.length;
      scratchSegments.positions = positions;
      scratchSegments.lengths = scratchLengths;
      return scratchSegments;
    }

    if (intersectsIDL(polyline)) {
      positions = polyline._segments.positions;
    }

    var ellipsoid = projection.ellipsoid;
    var newPositions = [];
    var modelMatrix = this.modelMatrix;
    var length = positions.length;
    var position;
    var p = pscratch;

    for (var n = 0; n < length; ++n) {
      position = positions[n];
      p = Matrix4.multiplyByPoint(modelMatrix, position, p);
      newPositions.push(
        projection.project(
          ellipsoid.cartesianToCartographic(p, scratchCartographic$6)
        )
      );
    }

    if (newPositions.length > 0) {
      polyline._boundingVolume2D = BoundingSphere.fromPoints(
        newPositions,
        polyline._boundingVolume2D
      );
      var center2D = polyline._boundingVolume2D.center;
      polyline._boundingVolume2D.center = new Cartesian3(
        center2D.z,
        center2D.x,
        center2D.y
      );
    }

    scratchSegments.positions = newPositions;
    scratchSegments.lengths = polyline._segments.lengths;
    return scratchSegments;
  };

  var scratchPositionsArray;

  PolylineBucket.prototype.writeUpdate = function (
    index,
    polyline,
    positionBuffer,
    projection
  ) {
    var mode = this.mode;
    var maxLon = projection.ellipsoid.maximumRadius * CesiumMath.PI;

    var positionsLength = polyline._actualLength;
    if (positionsLength) {
      index += this.getPolylineStartIndex(polyline);

      var positionArray = scratchPositionsArray;
      var positionsArrayLength = 6 * positionsLength * 3;

      if (
        !defined(positionArray) ||
        positionArray.length < positionsArrayLength
      ) {
        positionArray = scratchPositionsArray = new Float32Array(
          positionsArrayLength
        );
      } else if (positionArray.length > positionsArrayLength) {
        positionArray = new Float32Array(
          positionArray.buffer,
          0,
          positionsArrayLength
        );
      }

      var segments = this.getSegments(polyline, projection);
      var positions = segments.positions;
      var lengths = segments.lengths;

      var positionIndex = 0;
      var segmentIndex = 0;
      var count = 0;
      var position;

      positionsLength = positions.length;
      for (var i = 0; i < positionsLength; ++i) {
        if (i === 0) {
          if (polyline._loop) {
            position = positions[positionsLength - 2];
          } else {
            position = scratchWriteVector;
            Cartesian3.subtract(positions[0], positions[1], position);
            Cartesian3.add(positions[0], position, position);
          }
        } else {
          position = positions[i - 1];
        }

        Cartesian3.clone(position, scratchWritePrevPosition);
        Cartesian3.clone(positions[i], scratchWritePosition);

        if (i === positionsLength - 1) {
          if (polyline._loop) {
            position = positions[1];
          } else {
            position = scratchWriteVector;
            Cartesian3.subtract(
              positions[positionsLength - 1],
              positions[positionsLength - 2],
              position
            );
            Cartesian3.add(positions[positionsLength - 1], position, position);
          }
        } else {
          position = positions[i + 1];
        }

        Cartesian3.clone(position, scratchWriteNextPosition);

        var segmentLength = lengths[segmentIndex];
        if (i === count + segmentLength) {
          count += segmentLength;
          ++segmentIndex;
        }

        var segmentStart = i - count === 0;
        var segmentEnd = i === count + lengths[segmentIndex] - 1;

        if (mode === SceneMode$1.SCENE2D) {
          scratchWritePrevPosition.z = 0.0;
          scratchWritePosition.z = 0.0;
          scratchWriteNextPosition.z = 0.0;
        }

        if (mode === SceneMode$1.SCENE2D || mode === SceneMode$1.MORPHING) {
          if (
            (segmentStart || segmentEnd) &&
            maxLon - Math.abs(scratchWritePosition.x) < 1.0
          ) {
            if (
              (scratchWritePosition.x < 0.0 &&
                scratchWritePrevPosition.x > 0.0) ||
              (scratchWritePosition.x > 0.0 && scratchWritePrevPosition.x < 0.0)
            ) {
              Cartesian3.clone(scratchWritePosition, scratchWritePrevPosition);
            }

            if (
              (scratchWritePosition.x < 0.0 &&
                scratchWriteNextPosition.x > 0.0) ||
              (scratchWritePosition.x > 0.0 && scratchWriteNextPosition.x < 0.0)
            ) {
              Cartesian3.clone(scratchWritePosition, scratchWriteNextPosition);
            }
          }
        }

        var startJ = segmentStart ? 2 : 0;
        var endJ = segmentEnd ? 2 : 4;

        for (var j = startJ; j < endJ; ++j) {
          EncodedCartesian3.writeElements(
            scratchWritePosition,
            positionArray,
            positionIndex
          );
          EncodedCartesian3.writeElements(
            scratchWritePrevPosition,
            positionArray,
            positionIndex + 6
          );
          EncodedCartesian3.writeElements(
            scratchWriteNextPosition,
            positionArray,
            positionIndex + 12
          );
          positionIndex += 6 * 3;
        }
      }

      positionBuffer.copyFromArrayView(
        positionArray,
        6 * 3 * Float32Array.BYTES_PER_ELEMENT * index
      );
    }
  };

  /**
   * Creates a batch of points or billboards and labels.
   *
   * @alias Vector3DTilePoints
   * @constructor
   *
   * @param {Object} options An object with following properties:
   * @param {Uint16Array} options.positions The positions of the polygons.
   * @param {Number} options.minimumHeight The minimum height of the terrain covered by the tile.
   * @param {Number} options.maximumHeight The maximum height of the terrain covered by the tile.
   * @param {Rectangle} options.rectangle The rectangle containing the tile.
   * @param {Cesium3DTileBatchTable} options.batchTable The batch table for the tile containing the batched polygons.
   * @param {Uint16Array} options.batchIds The batch ids for each polygon.
   *
   * @private
   */
  function Vector3DTilePoints(options) {
    // released after the first update
    this._positions = options.positions;

    this._batchTable = options.batchTable;
    this._batchIds = options.batchIds;

    this._rectangle = options.rectangle;
    this._minHeight = options.minimumHeight;
    this._maxHeight = options.maximumHeight;

    this._billboardCollection = undefined;
    this._labelCollection = undefined;
    this._polylineCollection = undefined;

    this._verticesPromise = undefined;
    this._packedBuffer = undefined;

    this._ready = false;
    this._readyPromise = when.defer();
    this._resolvedPromise = false;
  }

  Object.defineProperties(Vector3DTilePoints.prototype, {
    /**
     * Gets the number of points.
     *
     * @memberof Vector3DTilePoints.prototype
     *
     * @type {Number}
     * @readonly
     */
    pointsLength: {
      get: function () {
        return this._billboardCollection.length;
      },
    },

    /**
     * Gets the texture atlas memory in bytes.
     *
     * @memberof Vector3DTilePoints.prototype
     *
     * @type {Number}
     * @readonly
     */
    texturesByteLength: {
      get: function () {
        var billboardSize = this._billboardCollection.textureAtlas.texture
          .sizeInBytes;
        var labelSize = this._labelCollection._textureAtlas.texture.sizeInBytes;
        return billboardSize + labelSize;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof Vector3DTilePoints.prototype
     * @type {Promise<void>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  function packBuffer$1(points, ellipsoid) {
    var rectangle = points._rectangle;
    var minimumHeight = points._minHeight;
    var maximumHeight = points._maxHeight;

    var packedLength = 2 + Rectangle.packedLength + Ellipsoid.packedLength;
    var packedBuffer = new Float64Array(packedLength);

    var offset = 0;
    packedBuffer[offset++] = minimumHeight;
    packedBuffer[offset++] = maximumHeight;

    Rectangle.pack(rectangle, packedBuffer, offset);
    offset += Rectangle.packedLength;

    Ellipsoid.pack(ellipsoid, packedBuffer, offset);

    return packedBuffer;
  }

  var createVerticesTaskProcessor$1 = new TaskProcessor("createVectorTilePoints");
  var scratchPosition$9 = new Cartesian3();

  function createPoints(points, ellipsoid) {
    if (defined(points._billboardCollection)) {
      return;
    }

    var positions;
    if (!defined(points._verticesPromise)) {
      positions = points._positions;
      var packedBuffer = points._packedBuffer;

      if (!defined(packedBuffer)) {
        // Copy because they may be the views on the same buffer.
        positions = points._positions = arraySlice(positions);
        points._batchIds = arraySlice(points._batchIds);

        packedBuffer = points._packedBuffer = packBuffer$1(points, ellipsoid);
      }

      var transferrableObjects = [positions.buffer, packedBuffer.buffer];
      var parameters = {
        positions: positions.buffer,
        packedBuffer: packedBuffer.buffer,
      };

      var verticesPromise = (points._verticesPromise = createVerticesTaskProcessor$1.scheduleTask(
        parameters,
        transferrableObjects
      ));
      if (!defined(verticesPromise)) {
        // Postponed
        return;
      }

      verticesPromise.then(function (result) {
        points._positions = new Float64Array(result.positions);
        points._ready = true;
      });
    }

    if (points._ready && !defined(points._billboardCollection)) {
      positions = points._positions;
      var batchTable = points._batchTable;
      var batchIds = points._batchIds;

      var billboardCollection = (points._billboardCollection = new BillboardCollection(
        { batchTable: batchTable }
      ));
      var labelCollection = (points._labelCollection = new LabelCollection({
        batchTable: batchTable,
      }));
      var polylineCollection = (points._polylineCollection = new PolylineCollection());
      polylineCollection._useHighlightColor = true;

      var numberOfPoints = positions.length / 3;
      for (var i = 0; i < numberOfPoints; ++i) {
        var id = batchIds[i];

        var position = Cartesian3.unpack(positions, i * 3, scratchPosition$9);

        var b = billboardCollection.add();
        b.position = position;
        b._batchIndex = id;

        var l = labelCollection.add();
        l.text = " ";
        l.position = position;
        l._batchIndex = id;

        var p = polylineCollection.add();
        p.positions = [Cartesian3.clone(position), Cartesian3.clone(position)];
      }

      points._positions = undefined;
      points._packedBuffer = undefined;
    }
  }

  /**
   * Creates features for each point and places it at the batch id index of features.
   *
   * @param {Vector3DTileContent} content The vector tile content.
   * @param {Cesium3DTileFeature[]} features An array of features where the point features will be placed.
   */
  Vector3DTilePoints.prototype.createFeatures = function (content, features) {
    var billboardCollection = this._billboardCollection;
    var labelCollection = this._labelCollection;
    var polylineCollection = this._polylineCollection;

    var batchIds = this._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];

      var billboard = billboardCollection.get(i);
      var label = labelCollection.get(i);
      var polyline = polylineCollection.get(i);

      features[batchId] = new Cesium3DTilePointFeature(
        content,
        batchId,
        billboard,
        label,
        polyline
      );
    }
  };

  /**
   * Colors the entire tile when enabled is true. The resulting color will be (batch table color * color).
   *
   * @param {Boolean} enabled Whether to enable debug coloring.
   * @param {Color} color The debug color.
   */
  Vector3DTilePoints.prototype.applyDebugSettings = function (enabled, color) {
    if (enabled) {
      Color.clone(color, this._billboardCollection._highlightColor);
      Color.clone(color, this._labelCollection._highlightColor);
      Color.clone(color, this._polylineCollection._highlightColor);
    } else {
      Color.clone(Color.WHITE, this._billboardCollection._highlightColor);
      Color.clone(Color.WHITE, this._labelCollection._highlightColor);
      Color.clone(Color.WHITE, this._polylineCollection._highlightColor);
    }
  };

  function clearStyle$1(polygons, features) {
    var batchIds = polygons._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      var feature = features[batchId];

      feature.show = true;
      feature.pointSize = Cesium3DTilePointFeature.defaultPointSize;
      feature.color = Cesium3DTilePointFeature.defaultColor;
      feature.pointOutlineColor =
        Cesium3DTilePointFeature.defaultPointOutlineColor;
      feature.pointOutlineWidth =
        Cesium3DTilePointFeature.defaultPointOutlineWidth;
      feature.labelColor = Color.WHITE;
      feature.labelOutlineColor = Color.WHITE;
      feature.labelOutlineWidth = 1.0;
      feature.font = "30px sans-serif";
      feature.labelStyle = LabelStyle$1.FILL;
      feature.labelText = undefined;
      feature.backgroundColor = new Color(0.165, 0.165, 0.165, 0.8);
      feature.backgroundPadding = new Cartesian2(7, 5);
      feature.backgroundEnabled = false;
      feature.scaleByDistance = undefined;
      feature.translucencyByDistance = undefined;
      feature.distanceDisplayCondition = undefined;
      feature.heightOffset = 0.0;
      feature.anchorLineEnabled = false;
      feature.anchorLineColor = Color.WHITE;
      feature.image = undefined;
      feature.disableDepthTestDistance = 0.0;
      feature.horizontalOrigin = HorizontalOrigin$1.CENTER;
      feature.verticalOrigin = VerticalOrigin$1.CENTER;
      feature.labelHorizontalOrigin = HorizontalOrigin$1.RIGHT;
      feature.labelVerticalOrigin = VerticalOrigin$1.BASELINE;
    }
  }

  var scratchColor$6 = new Color();
  var scratchColor2 = new Color();
  var scratchColor3 = new Color();
  var scratchColor4 = new Color();
  var scratchColor5 = new Color();
  var scratchColor6 = new Color();
  var scratchScaleByDistance = new NearFarScalar();
  var scratchTranslucencyByDistance = new NearFarScalar();
  var scratchDistanceDisplayCondition = new DistanceDisplayCondition();

  /**
   * Apply a style to the content.
   *
   * @param {Cesium3DTileStyle} style The style.
   * @param {Cesium3DTileFeature[]} features The array of features.
   */
  Vector3DTilePoints.prototype.applyStyle = function (style, features) {
    if (!defined(style)) {
      clearStyle$1(this, features);
      return;
    }

    var batchIds = this._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      var feature = features[batchId];

      if (defined(style.show)) {
        feature.show = style.show.evaluate(feature);
      }

      if (defined(style.pointSize)) {
        feature.pointSize = style.pointSize.evaluate(feature);
      }

      if (defined(style.color)) {
        feature.color = style.color.evaluateColor(feature, scratchColor$6);
      }

      if (defined(style.pointOutlineColor)) {
        feature.pointOutlineColor = style.pointOutlineColor.evaluateColor(
          feature,
          scratchColor2
        );
      }

      if (defined(style.pointOutlineWidth)) {
        feature.pointOutlineWidth = style.pointOutlineWidth.evaluate(feature);
      }

      if (defined(style.labelColor)) {
        feature.labelColor = style.labelColor.evaluateColor(
          feature,
          scratchColor3
        );
      }

      if (defined(style.labelOutlineColor)) {
        feature.labelOutlineColor = style.labelOutlineColor.evaluateColor(
          feature,
          scratchColor4
        );
      }

      if (defined(style.labelOutlineWidth)) {
        feature.labelOutlineWidth = style.labelOutlineWidth.evaluate(feature);
      }

      if (defined(style.font)) {
        feature.font = style.font.evaluate(feature);
      }

      if (defined(style.labelStyle)) {
        feature.labelStyle = style.labelStyle.evaluate(feature);
      }

      if (defined(style.labelText)) {
        feature.labelText = style.labelText.evaluate(feature);
      } else {
        feature.labelText = undefined;
      }

      if (defined(style.backgroundColor)) {
        feature.backgroundColor = style.backgroundColor.evaluateColor(
          feature,
          scratchColor5
        );
      }

      if (defined(style.backgroundPadding)) {
        feature.backgroundPadding = style.backgroundPadding.evaluate(feature);
      }

      if (defined(style.backgroundEnabled)) {
        feature.backgroundEnabled = style.backgroundEnabled.evaluate(feature);
      }

      if (defined(style.scaleByDistance)) {
        var scaleByDistanceCart4 = style.scaleByDistance.evaluate(feature);
        scratchScaleByDistance.near = scaleByDistanceCart4.x;
        scratchScaleByDistance.nearValue = scaleByDistanceCart4.y;
        scratchScaleByDistance.far = scaleByDistanceCart4.z;
        scratchScaleByDistance.farValue = scaleByDistanceCart4.w;
        feature.scaleByDistance = scratchScaleByDistance;
      } else {
        feature.scaleByDistance = undefined;
      }

      if (defined(style.translucencyByDistance)) {
        var translucencyByDistanceCart4 = style.translucencyByDistance.evaluate(
          feature
        );
        scratchTranslucencyByDistance.near = translucencyByDistanceCart4.x;
        scratchTranslucencyByDistance.nearValue = translucencyByDistanceCart4.y;
        scratchTranslucencyByDistance.far = translucencyByDistanceCart4.z;
        scratchTranslucencyByDistance.farValue = translucencyByDistanceCart4.w;
        feature.translucencyByDistance = scratchTranslucencyByDistance;
      } else {
        feature.translucencyByDistance = undefined;
      }

      if (defined(style.distanceDisplayCondition)) {
        var distanceDisplayConditionCart2 = style.distanceDisplayCondition.evaluate(
          feature
        );
        scratchDistanceDisplayCondition.near = distanceDisplayConditionCart2.x;
        scratchDistanceDisplayCondition.far = distanceDisplayConditionCart2.y;
        feature.distanceDisplayCondition = scratchDistanceDisplayCondition;
      } else {
        feature.distanceDisplayCondition = undefined;
      }

      if (defined(style.heightOffset)) {
        feature.heightOffset = style.heightOffset.evaluate(feature);
      }

      if (defined(style.anchorLineEnabled)) {
        feature.anchorLineEnabled = style.anchorLineEnabled.evaluate(feature);
      }

      if (defined(style.anchorLineColor)) {
        feature.anchorLineColor = style.anchorLineColor.evaluateColor(
          feature,
          scratchColor6
        );
      }

      if (defined(style.image)) {
        feature.image = style.image.evaluate(feature);
      } else {
        feature.image = undefined;
      }

      if (defined(style.disableDepthTestDistance)) {
        feature.disableDepthTestDistance = style.disableDepthTestDistance.evaluate(
          feature
        );
      }

      if (defined(style.horizontalOrigin)) {
        feature.horizontalOrigin = style.horizontalOrigin.evaluate(feature);
      }

      if (defined(style.verticalOrigin)) {
        feature.verticalOrigin = style.verticalOrigin.evaluate(feature);
      }

      if (defined(style.labelHorizontalOrigin)) {
        feature.labelHorizontalOrigin = style.labelHorizontalOrigin.evaluate(
          feature
        );
      }

      if (defined(style.labelVerticalOrigin)) {
        feature.labelVerticalOrigin = style.labelVerticalOrigin.evaluate(feature);
      }
    }
  };

  /**
   * @private
   */
  Vector3DTilePoints.prototype.update = function (frameState) {
    createPoints(this, frameState.mapProjection.ellipsoid);

    if (!this._ready) {
      return;
    }

    this._polylineCollection.update(frameState);
    this._billboardCollection.update(frameState);
    this._labelCollection.update(frameState);

    if (!this._resolvedPromise) {
      this._readyPromise.resolve();
      this._resolvedPromise = true;
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  Vector3DTilePoints.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  Vector3DTilePoints.prototype.destroy = function () {
    this._billboardCollection =
      this._billboardCollection && this._billboardCollection.destroy();
    this._labelCollection =
      this._labelCollection && this._labelCollection.destroy();
    this._polylineCollection =
      this._polylineCollection && this._polylineCollection.destroy();
    return destroyObject(this);
  };

  /**
   * Creates a batch of pre-triangulated polygons draped on terrain and/or 3D Tiles.
   *
   * @alias Vector3DTilePolygons
   * @constructor
   *
   * @param {Object} options An object with following properties:
   * @param {Float32Array|Uint16Array} options.positions The positions of the polygons. The positions must be contiguous
   * so that the positions for polygon n are in [c, c + counts[n]] where c = sum{counts[0], counts[n - 1]} and they are the outer ring of
   * the polygon in counter-clockwise order.
   * @param {Uint32Array} options.counts The number of positions in the each polygon.
   * @param {Uint32Array} options.indices The indices of the triangulated polygons. The indices must be contiguous so that
   * the indices for polygon n are in [i, i + indexCounts[n]] where i = sum{indexCounts[0], indexCounts[n - 1]}.
   * @param {Uint32Array} options.indexCounts The number of indices for each polygon.
   * @param {Number} options.minimumHeight The minimum height of the terrain covered by the tile.
   * @param {Number} options.maximumHeight The maximum height of the terrain covered by the tile.
   * @param {Float32Array} [options.polygonMinimumHeights] An array containing the minimum heights for each polygon.
   * @param {Float32Array} [options.polygonMaximumHeights] An array containing the maximum heights for each polygon.
   * @param {Rectangle} options.rectangle The rectangle containing the tile.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid.
   * @param {Cartesian3} [options.center=Cartesian3.ZERO] The RTC center.
   * @param {Cesium3DTileBatchTable} options.batchTable The batch table for the tile containing the batched polygons.
   * @param {Uint16Array} options.batchIds The batch ids for each polygon.
   * @param {BoundingSphere} options.boundingVolume The bounding volume for the entire batch of polygons.
   *
   * @private
   */
  function Vector3DTilePolygons(options) {
    // All of the private properties will be released except _readyPromise
    // and _primitive after the Vector3DTilePrimitive is created.
    this._batchTable = options.batchTable;

    this._batchIds = options.batchIds;
    this._positions = options.positions;
    this._counts = options.counts;

    this._indices = options.indices;
    this._indexCounts = options.indexCounts;
    this._indexOffsets = undefined;

    this._batchTableColors = undefined;
    this._packedBuffer = undefined;

    this._batchedPositions = undefined;
    this._transferrableBatchIds = undefined;
    this._vertexBatchIds = undefined;

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    this._minimumHeight = options.minimumHeight;
    this._maximumHeight = options.maximumHeight;
    this._polygonMinimumHeights = options.polygonMinimumHeights;
    this._polygonMaximumHeights = options.polygonMaximumHeights;
    this._center = defaultValue(options.center, Cartesian3.ZERO);
    this._rectangle = options.rectangle;

    this._center = undefined;

    this._boundingVolume = options.boundingVolume;
    this._boundingVolumes = undefined;

    this._batchedIndices = undefined;

    this._ready = false;
    this._readyPromise = when.defer();

    this._verticesPromise = undefined;

    this._primitive = undefined;

    /**
     * Draws the wireframe of the classification meshes.
     * @type {Boolean}
     * @default false
     */
    this.debugWireframe = false;

    /**
     * Forces a re-batch instead of waiting after a number of frames have been rendered. For testing only.
     * @type {Boolean}
     * @default false
     */
    this.forceRebatch = false;

    /**
     * What this tile will classify.
     * @type {ClassificationType}
     * @default ClassificationType.BOTH
     */
    this.classificationType = ClassificationType$1.BOTH;
  }

  Object.defineProperties(Vector3DTilePolygons.prototype, {
    /**
     * Gets the number of triangles.
     *
     * @memberof Vector3DTilePolygons.prototype
     *
     * @type {Number}
     * @readonly
     */
    trianglesLength: {
      get: function () {
        if (defined(this._primitive)) {
          return this._primitive.trianglesLength;
        }
        return 0;
      },
    },

    /**
     * Gets the geometry memory in bytes.
     *
     * @memberof Vector3DTilePolygons.prototype
     *
     * @type {Number}
     * @readonly
     */
    geometryByteLength: {
      get: function () {
        if (defined(this._primitive)) {
          return this._primitive.geometryByteLength;
        }
        return 0;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof Vector3DTilePolygons.prototype
     * @type {Promise<void>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  function packBuffer$2(polygons) {
    var packedBuffer = new Float64Array(
      3 +
        Cartesian3.packedLength +
        Ellipsoid.packedLength +
        Rectangle.packedLength
    );

    var offset = 0;
    packedBuffer[offset++] = polygons._indices.BYTES_PER_ELEMENT;

    packedBuffer[offset++] = polygons._minimumHeight;
    packedBuffer[offset++] = polygons._maximumHeight;

    Cartesian3.pack(polygons._center, packedBuffer, offset);
    offset += Cartesian3.packedLength;

    Ellipsoid.pack(polygons._ellipsoid, packedBuffer, offset);
    offset += Ellipsoid.packedLength;

    Rectangle.pack(polygons._rectangle, packedBuffer, offset);

    return packedBuffer;
  }

  function unpackBuffer$1(polygons, packedBuffer) {
    var offset = 1;

    var numBVS = packedBuffer[offset++];
    var bvs = (polygons._boundingVolumes = new Array(numBVS));

    for (var i = 0; i < numBVS; ++i) {
      bvs[i] = OrientedBoundingBox.unpack(packedBuffer, offset);
      offset += OrientedBoundingBox.packedLength;
    }

    var numBatchedIndices = packedBuffer[offset++];
    var bis = (polygons._batchedIndices = new Array(numBatchedIndices));

    for (var j = 0; j < numBatchedIndices; ++j) {
      var color = Color.unpack(packedBuffer, offset);
      offset += Color.packedLength;

      var indexOffset = packedBuffer[offset++];
      var count = packedBuffer[offset++];

      var length = packedBuffer[offset++];
      var batchIds = new Array(length);

      for (var k = 0; k < length; ++k) {
        batchIds[k] = packedBuffer[offset++];
      }

      bis[j] = new Vector3DTileBatch({
        color: color,
        offset: indexOffset,
        count: count,
        batchIds: batchIds,
      });
    }
  }

  var createVerticesTaskProcessor$2 = new TaskProcessor("createVectorTilePolygons");
  var scratchColor$7 = new Color();

  function createPrimitive$2(polygons) {
    if (defined(polygons._primitive)) {
      return;
    }

    if (!defined(polygons._verticesPromise)) {
      var positions = polygons._positions;
      var counts = polygons._counts;
      var indexCounts = polygons._indexCounts;
      var indices = polygons._indices;

      var batchIds = polygons._transferrableBatchIds;
      var batchTableColors = polygons._batchTableColors;

      var packedBuffer = polygons._packedBuffer;

      if (!defined(batchTableColors)) {
        // Copy because they may be the views on the same buffer.
        positions = polygons._positions = arraySlice(polygons._positions);
        counts = polygons._counts = arraySlice(polygons._counts);
        indexCounts = polygons._indexCounts = arraySlice(polygons._indexCounts);
        indices = polygons._indices = arraySlice(polygons._indices);

        polygons._center = polygons._ellipsoid.cartographicToCartesian(
          Rectangle.center(polygons._rectangle)
        );

        batchIds = polygons._transferrableBatchIds = new Uint32Array(
          polygons._batchIds
        );
        batchTableColors = polygons._batchTableColors = new Uint32Array(
          batchIds.length
        );
        var batchTable = polygons._batchTable;

        var length = batchTableColors.length;
        for (var i = 0; i < length; ++i) {
          var color = batchTable.getColor(i, scratchColor$7);
          batchTableColors[i] = color.toRgba();
        }

        packedBuffer = polygons._packedBuffer = packBuffer$2(polygons);
      }

      var transferrableObjects = [
        positions.buffer,
        counts.buffer,
        indexCounts.buffer,
        indices.buffer,
        batchIds.buffer,
        batchTableColors.buffer,
        packedBuffer.buffer,
      ];
      var parameters = {
        packedBuffer: packedBuffer.buffer,
        positions: positions.buffer,
        counts: counts.buffer,
        indexCounts: indexCounts.buffer,
        indices: indices.buffer,
        batchIds: batchIds.buffer,
        batchTableColors: batchTableColors.buffer,
      };

      var minimumHeights = polygons._polygonMinimumHeights;
      var maximumHeights = polygons._polygonMaximumHeights;
      if (defined(minimumHeights) && defined(maximumHeights)) {
        minimumHeights = arraySlice(minimumHeights);
        maximumHeights = arraySlice(maximumHeights);

        transferrableObjects.push(minimumHeights.buffer, maximumHeights.buffer);
        parameters.minimumHeights = minimumHeights;
        parameters.maximumHeights = maximumHeights;
      }

      var verticesPromise = (polygons._verticesPromise = createVerticesTaskProcessor$2.scheduleTask(
        parameters,
        transferrableObjects
      ));
      if (!defined(verticesPromise)) {
        // Postponed
        return;
      }

      when(verticesPromise, function (result) {
        polygons._positions = undefined;
        polygons._counts = undefined;
        polygons._polygonMinimumHeights = undefined;
        polygons._polygonMaximumHeights = undefined;

        var packedBuffer = new Float64Array(result.packedBuffer);
        var indexDatatype = packedBuffer[0];
        unpackBuffer$1(polygons, packedBuffer);

        polygons._indices =
          IndexDatatype$1.getSizeInBytes(indexDatatype) === 2
            ? new Uint16Array(result.indices)
            : new Uint32Array(result.indices);
        polygons._indexOffsets = new Uint32Array(result.indexOffsets);
        polygons._indexCounts = new Uint32Array(result.indexCounts);

        // will be released
        polygons._batchedPositions = new Float32Array(result.positions);
        polygons._vertexBatchIds = new Uint16Array(result.batchIds);

        polygons._ready = true;
      });
    }

    if (polygons._ready && !defined(polygons._primitive)) {
      polygons._primitive = new Vector3DTilePrimitive({
        batchTable: polygons._batchTable,
        positions: polygons._batchedPositions,
        batchIds: polygons._batchIds,
        vertexBatchIds: polygons._vertexBatchIds,
        indices: polygons._indices,
        indexOffsets: polygons._indexOffsets,
        indexCounts: polygons._indexCounts,
        batchedIndices: polygons._batchedIndices,
        boundingVolume: polygons._boundingVolume,
        boundingVolumes: polygons._boundingVolumes,
        center: polygons._center,
      });

      polygons._batchTable = undefined;
      polygons._batchIds = undefined;
      polygons._positions = undefined;
      polygons._counts = undefined;
      polygons._indices = undefined;
      polygons._indexCounts = undefined;
      polygons._indexOffsets = undefined;
      polygons._batchTableColors = undefined;
      polygons._packedBuffer = undefined;
      polygons._batchedPositions = undefined;
      polygons._transferrableBatchIds = undefined;
      polygons._vertexBatchIds = undefined;
      polygons._ellipsoid = undefined;
      polygons._minimumHeight = undefined;
      polygons._maximumHeight = undefined;
      polygons._polygonMinimumHeights = undefined;
      polygons._polygonMaximumHeights = undefined;
      polygons._center = undefined;
      polygons._rectangle = undefined;
      polygons._boundingVolume = undefined;
      polygons._boundingVolumes = undefined;
      polygons._batchedIndices = undefined;
      polygons._verticesPromise = undefined;

      polygons._readyPromise.resolve();
    }
  }

  /**
   * Creates features for each polygon and places it at the batch id index of features.
   *
   * @param {Vector3DTileContent} content The vector tile content.
   * @param {Cesium3DTileFeature[]} features An array of features where the polygon features will be placed.
   */
  Vector3DTilePolygons.prototype.createFeatures = function (content, features) {
    this._primitive.createFeatures(content, features);
  };

  /**
   * Colors the entire tile when enabled is true. The resulting color will be (polygon batch table color * color).
   *
   * @param {Boolean} enabled Whether to enable debug coloring.
   * @param {Color} color The debug color.
   */
  Vector3DTilePolygons.prototype.applyDebugSettings = function (enabled, color) {
    this._primitive.applyDebugSettings(enabled, color);
  };

  /**
   * Apply a style to the content.
   *
   * @param {Cesium3DTileStyle} style The style.
   * @param {Cesium3DTileFeature[]} features The array of features.
   */
  Vector3DTilePolygons.prototype.applyStyle = function (style, features) {
    this._primitive.applyStyle(style, features);
  };

  /**
   * Call when updating the color of a polygon with batchId changes color. The polygons will need to be re-batched
   * on the next update.
   *
   * @param {Number} batchId The batch id of the polygon whose color has changed.
   * @param {Color} color The new polygon color.
   */
  Vector3DTilePolygons.prototype.updateCommands = function (batchId, color) {
    this._primitive.updateCommands(batchId, color);
  };

  /**
   * Updates the batches and queues the commands for rendering.
   *
   * @param {FrameState} frameState The current frame state.
   */
  Vector3DTilePolygons.prototype.update = function (frameState) {
    createPrimitive$2(this);

    if (!this._ready) {
      return;
    }

    this._primitive.debugWireframe = this.debugWireframe;
    this._primitive.forceRebatch = this.forceRebatch;
    this._primitive.classificationType = this.classificationType;
    this._primitive.update(frameState);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  Vector3DTilePolygons.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  Vector3DTilePolygons.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var Vector3DTilePolylinesVS = "attribute vec4 currentPosition;\n\
attribute vec4 previousPosition;\n\
attribute vec4 nextPosition;\n\
attribute vec2 expandAndWidth;\n\
attribute float a_batchId;\n\
uniform mat4 u_modifiedModelView;\n\
void main()\n\
{\n\
float expandDir = expandAndWidth.x;\n\
float width = abs(expandAndWidth.y) + 0.5;\n\
bool usePrev = expandAndWidth.y < 0.0;\n\
vec4 p = u_modifiedModelView * currentPosition;\n\
vec4 prev = u_modifiedModelView * previousPosition;\n\
vec4 next = u_modifiedModelView * nextPosition;\n\
float angle;\n\
vec4 positionWC = getPolylineWindowCoordinatesEC(p, prev, next, expandDir, width, usePrev, angle);\n\
gl_Position = czm_viewportOrthographic * positionWC;\n\
}\n\
";

  /**
   * Creates a batch of polylines that have been subdivided to be draped on terrain.
   *
   * @alias Vector3DTilePolylines
   * @constructor
   *
   * @param {Object} options An object with following properties:
   * @param {Uint16Array} options.positions The positions of the polylines
   * @param {Uint32Array} options.counts The number or positions in the each polyline.
   * @param {Uint16Array} options.widths The width of each polyline.
   * @param {Number} options.minimumHeight The minimum height of the terrain covered by the tile.
   * @param {Number} options.maximumHeight The maximum height of the terrain covered by the tile.
   * @param {Rectangle} options.rectangle The rectangle containing the tile.
   * @param {Cartesian3} [options.center=Cartesian3.ZERO] The RTC center.
   * @param {Cesium3DTileBatchTable} options.batchTable The batch table for the tile containing the batched polylines.
   * @param {Uint16Array} options.batchIds The batch ids for each polyline.
   * @param {BoundingSphere} options.boundingVolume The bounding volume for the entire batch of polylines.
   *
   * @private
   */
  function Vector3DTilePolylines(options) {
    // these arrays are all released after the first update.
    this._positions = options.positions;
    this._widths = options.widths;
    this._counts = options.counts;
    this._batchIds = options.batchIds;

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    this._minimumHeight = options.minimumHeight;
    this._maximumHeight = options.maximumHeight;
    this._center = options.center;
    this._rectangle = options.rectangle;

    this._boundingVolume = options.boundingVolume;
    this._batchTable = options.batchTable;

    this._va = undefined;
    this._sp = undefined;
    this._rs = undefined;
    this._uniformMap = undefined;
    this._command = undefined;

    this._transferrableBatchIds = undefined;
    this._packedBuffer = undefined;

    this._currentPositions = undefined;
    this._previousPositions = undefined;
    this._nextPositions = undefined;
    this._expandAndWidth = undefined;
    this._vertexBatchIds = undefined;
    this._indices = undefined;

    this._constantColor = Color.clone(Color.WHITE);
    this._highlightColor = this._constantColor;

    this._trianglesLength = 0;
    this._geometryByteLength = 0;

    this._ready = false;
    this._readyPromise = when.defer();

    this._verticesPromise = undefined;
  }

  Object.defineProperties(Vector3DTilePolylines.prototype, {
    /**
     * Gets the number of triangles.
     *
     * @memberof Vector3DTilePolylines.prototype
     *
     * @type {Number}
     * @readonly
     */
    trianglesLength: {
      get: function () {
        return this._trianglesLength;
      },
    },

    /**
     * Gets the geometry memory in bytes.
     *
     * @memberof Vector3DTilePolylines.prototype
     *
     * @type {Number}
     * @readonly
     */
    geometryByteLength: {
      get: function () {
        return this._geometryByteLength;
      },
    },

    /**
     * Gets a promise that resolves when the primitive is ready to render.
     * @memberof Vector3DTilePolylines.prototype
     * @type {Promise<void>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  function packBuffer$3(polylines) {
    var rectangle = polylines._rectangle;
    var minimumHeight = polylines._minimumHeight;
    var maximumHeight = polylines._maximumHeight;
    var ellipsoid = polylines._ellipsoid;
    var center = polylines._center;

    var packedLength =
      2 +
      Rectangle.packedLength +
      Ellipsoid.packedLength +
      Cartesian3.packedLength;
    var packedBuffer = new Float64Array(packedLength);

    var offset = 0;
    packedBuffer[offset++] = minimumHeight;
    packedBuffer[offset++] = maximumHeight;

    Rectangle.pack(rectangle, packedBuffer, offset);
    offset += Rectangle.packedLength;

    Ellipsoid.pack(ellipsoid, packedBuffer, offset);
    offset += Ellipsoid.packedLength;

    Cartesian3.pack(center, packedBuffer, offset);

    return packedBuffer;
  }

  var createVerticesTaskProcessor$3 = new TaskProcessor(
    "createVectorTilePolylines"
  );
  var attributeLocations$2 = {
    previousPosition: 0,
    currentPosition: 1,
    nextPosition: 2,
    expandAndWidth: 3,
    a_batchId: 4,
  };

  function createVertexArray$4(polylines, context) {
    if (defined(polylines._va)) {
      return;
    }

    if (!defined(polylines._verticesPromise)) {
      var positions = polylines._positions;
      var widths = polylines._widths;
      var counts = polylines._counts;
      var batchIds = polylines._transferrableBatchIds;

      var packedBuffer = polylines._packedBuffer;

      if (!defined(packedBuffer)) {
        // Copy because they may be the views on the same buffer.
        positions = polylines._positions = arraySlice(positions);
        widths = polylines._widths = arraySlice(widths);
        counts = polylines._counts = arraySlice(counts);

        batchIds = polylines._transferrableBatchIds = arraySlice(
          polylines._batchIds
        );

        packedBuffer = polylines._packedBuffer = packBuffer$3(polylines);
      }

      var transferrableObjects = [
        positions.buffer,
        widths.buffer,
        counts.buffer,
        batchIds.buffer,
        packedBuffer.buffer,
      ];
      var parameters = {
        positions: positions.buffer,
        widths: widths.buffer,
        counts: counts.buffer,
        batchIds: batchIds.buffer,
        packedBuffer: packedBuffer.buffer,
      };

      var verticesPromise = (polylines._verticesPromise = createVerticesTaskProcessor$3.scheduleTask(
        parameters,
        transferrableObjects
      ));
      if (!defined(verticesPromise)) {
        // Postponed
        return;
      }

      when(verticesPromise, function (result) {
        polylines._currentPositions = new Float32Array(result.currentPositions);
        polylines._previousPositions = new Float32Array(result.previousPositions);
        polylines._nextPositions = new Float32Array(result.nextPositions);
        polylines._expandAndWidth = new Float32Array(result.expandAndWidth);
        polylines._vertexBatchIds = new Uint16Array(result.batchIds);

        var indexDatatype = result.indexDatatype;
        polylines._indices =
          indexDatatype === IndexDatatype$1.UNSIGNED_SHORT
            ? new Uint16Array(result.indices)
            : new Uint32Array(result.indices);

        polylines._ready = true;
      });
    }

    if (polylines._ready && !defined(polylines._va)) {
      var curPositions = polylines._currentPositions;
      var prevPositions = polylines._previousPositions;
      var nextPositions = polylines._nextPositions;
      var expandAndWidth = polylines._expandAndWidth;
      var vertexBatchIds = polylines._vertexBatchIds;
      var indices = polylines._indices;

      var byteLength =
        prevPositions.byteLength +
        curPositions.byteLength +
        nextPositions.byteLength;
      byteLength +=
        expandAndWidth.byteLength +
        vertexBatchIds.byteLength +
        indices.byteLength;
      polylines._trianglesLength = indices.length / 3;
      polylines._geometryByteLength = byteLength;

      var prevPositionBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: prevPositions,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      var curPositionBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: curPositions,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      var nextPositionBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: nextPositions,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      var expandAndWidthBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: expandAndWidth,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      var idBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: vertexBatchIds,
        usage: BufferUsage$1.STATIC_DRAW,
      });

      var indexBuffer = Buffer$1.createIndexBuffer({
        context: context,
        typedArray: indices,
        usage: BufferUsage$1.STATIC_DRAW,
        indexDatatype:
          indices.BYTES_PER_ELEMENT === 2
            ? IndexDatatype$1.UNSIGNED_SHORT
            : IndexDatatype$1.UNSIGNED_INT,
      });

      var vertexAttributes = [
        {
          index: attributeLocations$2.previousPosition,
          vertexBuffer: prevPositionBuffer,
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          index: attributeLocations$2.currentPosition,
          vertexBuffer: curPositionBuffer,
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          index: attributeLocations$2.nextPosition,
          vertexBuffer: nextPositionBuffer,
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 3,
        },
        {
          index: attributeLocations$2.expandAndWidth,
          vertexBuffer: expandAndWidthBuffer,
          componentDatatype: ComponentDatatype$1.FLOAT,
          componentsPerAttribute: 2,
        },
        {
          index: attributeLocations$2.a_batchId,
          vertexBuffer: idBuffer,
          componentDatatype: ComponentDatatype$1.UNSIGNED_SHORT,
          componentsPerAttribute: 1,
        },
      ];

      polylines._va = new VertexArray({
        context: context,
        attributes: vertexAttributes,
        indexBuffer: indexBuffer,
      });

      polylines._positions = undefined;
      polylines._widths = undefined;
      polylines._counts = undefined;

      polylines._ellipsoid = undefined;
      polylines._minimumHeight = undefined;
      polylines._maximumHeight = undefined;
      polylines._rectangle = undefined;

      polylines._transferrableBatchIds = undefined;
      polylines._packedBuffer = undefined;

      polylines._currentPositions = undefined;
      polylines._previousPositions = undefined;
      polylines._nextPositions = undefined;
      polylines._expandAndWidth = undefined;
      polylines._vertexBatchIds = undefined;
      polylines._indices = undefined;

      polylines._readyPromise.resolve();
    }
  }

  var modifiedModelViewScratch$2 = new Matrix4();
  var rtcScratch$2 = new Cartesian3();

  function createUniformMap$3(primitive, context) {
    if (defined(primitive._uniformMap)) {
      return;
    }

    primitive._uniformMap = {
      u_modifiedModelView: function () {
        var viewMatrix = context.uniformState.view;
        Matrix4.clone(viewMatrix, modifiedModelViewScratch$2);
        Matrix4.multiplyByPoint(
          modifiedModelViewScratch$2,
          primitive._center,
          rtcScratch$2
        );
        Matrix4.setTranslation(
          modifiedModelViewScratch$2,
          rtcScratch$2,
          modifiedModelViewScratch$2
        );
        return modifiedModelViewScratch$2;
      },
      u_highlightColor: function () {
        return primitive._highlightColor;
      },
    };
  }

  function createRenderStates$4(primitive) {
    if (defined(primitive._rs)) {
      return;
    }

    var polygonOffset = {
      enabled: true,
      factor: -5.0,
      units: -5.0,
    };

    primitive._rs = RenderState.fromCache({
      blending: BlendingState$1.ALPHA_BLEND,
      depthMask: false,
      depthTest: {
        enabled: true,
      },
      polygonOffset: polygonOffset,
    });
  }

  var PolylineFS$1 =
    "uniform vec4 u_highlightColor; \n" +
    "void main()\n" +
    "{\n" +
    "    gl_FragColor = u_highlightColor;\n" +
    "}\n";

  function createShaders$2(primitive, context) {
    if (defined(primitive._sp)) {
      return;
    }

    var batchTable = primitive._batchTable;

    var vsSource = batchTable.getVertexShaderCallback(
      false,
      "a_batchId",
      undefined
    )(Vector3DTilePolylinesVS);
    var fsSource = batchTable.getFragmentShaderCallback()(
      PolylineFS$1,
      false,
      undefined
    );

    var vs = new ShaderSource({
      defines: [
        "VECTOR_TILE",
        !FeatureDetection.isInternetExplorer() ? "CLIP_POLYLINE" : "",
      ],
      sources: [PolylineCommon, vsSource],
    });
    var fs = new ShaderSource({
      defines: ["VECTOR_TILE"],
      sources: [fsSource],
    });

    primitive._sp = ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: vs,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations$2,
    });
  }

  function queueCommands$1(primitive, frameState) {
    if (!defined(primitive._command)) {
      var uniformMap = primitive._batchTable.getUniformMapCallback()(
        primitive._uniformMap
      );
      primitive._command = new DrawCommand({
        owner: primitive,
        vertexArray: primitive._va,
        renderState: primitive._rs,
        shaderProgram: primitive._sp,
        uniformMap: uniformMap,
        boundingVolume: primitive._boundingVolume,
        pass: Pass$1.TRANSLUCENT,
        pickId: primitive._batchTable.getPickId(),
      });
    }

    frameState.commandList.push(primitive._command);
  }

  /**
   * Creates features for each polyline and places it at the batch id index of features.
   *
   * @param {Vector3DTileContent} content The vector tile content.
   * @param {Cesium3DTileFeature[]} features An array of features where the polygon features will be placed.
   */
  Vector3DTilePolylines.prototype.createFeatures = function (content, features) {
    var batchIds = this._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      features[batchId] = new Cesium3DTileFeature(content, batchId);
    }
  };

  /**
   * Colors the entire tile when enabled is true. The resulting color will be (polyline batch table color * color).
   *
   * @param {Boolean} enabled Whether to enable debug coloring.
   * @param {Color} color The debug color.
   */
  Vector3DTilePolylines.prototype.applyDebugSettings = function (enabled, color) {
    this._highlightColor = enabled ? color : this._constantColor;
  };

  function clearStyle$2(polygons, features) {
    var batchIds = polygons._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      var feature = features[batchId];

      feature.show = true;
      feature.color = Color.WHITE;
    }
  }

  var scratchColor$8 = new Color();

  var DEFAULT_COLOR_VALUE$2 = Color.WHITE;
  var DEFAULT_SHOW_VALUE$2 = true;

  /**
   * Apply a style to the content.
   *
   * @param {Cesium3DTileStyle} style The style.
   * @param {Cesium3DTileFeature[]} features The array of features.
   */
  Vector3DTilePolylines.prototype.applyStyle = function (style, features) {
    if (!defined(style)) {
      clearStyle$2(this, features);
      return;
    }

    var batchIds = this._batchIds;
    var length = batchIds.length;
    for (var i = 0; i < length; ++i) {
      var batchId = batchIds[i];
      var feature = features[batchId];

      feature.color = defined(style.color)
        ? style.color.evaluateColor(feature, scratchColor$8)
        : DEFAULT_COLOR_VALUE$2;
      feature.show = defined(style.show)
        ? style.show.evaluate(feature)
        : DEFAULT_SHOW_VALUE$2;
    }
  };

  /**
   * Updates the batches and queues the commands for rendering.
   *
   * @param {FrameState} frameState The current frame state.
   */
  Vector3DTilePolylines.prototype.update = function (frameState) {
    var context = frameState.context;

    createVertexArray$4(this, context);
    createUniformMap$3(this, context);
    createShaders$2(this, context);
    createRenderStates$4(this);

    if (!this._ready) {
      return;
    }

    var passes = frameState.passes;
    if (passes.render || passes.pick) {
      queueCommands$1(this, frameState);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  Vector3DTilePolylines.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  Vector3DTilePolylines.prototype.destroy = function () {
    this._va = this._va && this._va.destroy();
    this._sp = this._sp && this._sp.destroy();
    return destroyObject(this);
  };

  /**
   * Represents the contents of a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/3d-tiles-next/TileFormats/VectorData|Vector}
   * tile in a {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Vector3DTileContent
   * @constructor
   *
   * @private
   */
  function Vector3DTileContent(tileset, tile, resource, arrayBuffer, byteOffset) {
    this._tileset = tileset;
    this._tile = tile;
    this._resource = resource;

    this._polygons = undefined;
    this._polylines = undefined;
    this._points = undefined;

    this._contentReadyPromise = undefined;
    this._readyPromise = when.defer();

    this._batchTable = undefined;
    this._features = undefined;

    /**
     * Part of the {@link Cesium3DTileContent} interface.
     */
    this.featurePropertiesDirty = false;

    initialize$8(this, arrayBuffer, byteOffset);
  }

  Object.defineProperties(Vector3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        return defined(this._batchTable) ? this._batchTable.featuresLength : 0;
      },
    },

    pointsLength: {
      get: function () {
        if (defined(this._points)) {
          return this._points.pointsLength;
        }
        return 0;
      },
    },

    trianglesLength: {
      get: function () {
        var trianglesLength = 0;
        if (defined(this._polygons)) {
          trianglesLength += this._polygons.trianglesLength;
        }
        if (defined(this._polylines)) {
          trianglesLength += this._polylines.trianglesLength;
        }
        return trianglesLength;
      },
    },

    geometryByteLength: {
      get: function () {
        var geometryByteLength = 0;
        if (defined(this._polygons)) {
          geometryByteLength += this._polygons.geometryByteLength;
        }
        if (defined(this._polylines)) {
          geometryByteLength += this._polylines.geometryByteLength;
        }
        return geometryByteLength;
      },
    },

    texturesByteLength: {
      get: function () {
        if (defined(this._points)) {
          return this._points.texturesByteLength;
        }
        return 0;
      },
    },

    batchTableByteLength: {
      get: function () {
        return defined(this._batchTable) ? this._batchTable.memorySizeInBytes : 0;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return this._resource.getUrlComponent(true);
      },
    },

    batchTable: {
      get: function () {
        return this._batchTable;
      },
    },
  });

  function createColorChangedCallback$2(content) {
    return function (batchId, color) {
      if (defined(content._polygons)) {
        content._polygons.updateCommands(batchId, color);
      }
    };
  }

  function getBatchIds$1(featureTableJson, featureTableBinary) {
    var polygonBatchIds;
    var polylineBatchIds;
    var pointBatchIds;
    var i;

    var numberOfPolygons = defaultValue(featureTableJson.POLYGONS_LENGTH, 0);
    var numberOfPolylines = defaultValue(featureTableJson.POLYLINES_LENGTH, 0);
    var numberOfPoints = defaultValue(featureTableJson.POINTS_LENGTH, 0);

    if (numberOfPolygons > 0 && defined(featureTableJson.POLYGON_BATCH_IDS)) {
      var polygonBatchIdsByteOffset =
        featureTableBinary.byteOffset +
        featureTableJson.POLYGON_BATCH_IDS.byteOffset;
      polygonBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        polygonBatchIdsByteOffset,
        numberOfPolygons
      );
    }

    if (numberOfPolylines > 0 && defined(featureTableJson.POLYLINE_BATCH_IDS)) {
      var polylineBatchIdsByteOffset =
        featureTableBinary.byteOffset +
        featureTableJson.POLYLINE_BATCH_IDS.byteOffset;
      polylineBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        polylineBatchIdsByteOffset,
        numberOfPolylines
      );
    }

    if (numberOfPoints > 0 && defined(featureTableJson.POINT_BATCH_IDS)) {
      var pointBatchIdsByteOffset =
        featureTableBinary.byteOffset +
        featureTableJson.POINT_BATCH_IDS.byteOffset;
      pointBatchIds = new Uint16Array(
        featureTableBinary.buffer,
        pointBatchIdsByteOffset,
        numberOfPoints
      );
    }

    var atLeastOneDefined =
      defined(polygonBatchIds) ||
      defined(polylineBatchIds) ||
      defined(pointBatchIds);
    var atLeastOneUndefined =
      (numberOfPolygons > 0 && !defined(polygonBatchIds)) ||
      (numberOfPolylines > 0 && !defined(polylineBatchIds)) ||
      (numberOfPoints > 0 && !defined(pointBatchIds));

    if (atLeastOneDefined && atLeastOneUndefined) {
      throw new RuntimeError(
        "If one group of batch ids is defined, then all batch ids must be defined."
      );
    }

    var allUndefinedBatchIds =
      !defined(polygonBatchIds) &&
      !defined(polylineBatchIds) &&
      !defined(pointBatchIds);
    if (allUndefinedBatchIds) {
      var id = 0;
      if (!defined(polygonBatchIds) && numberOfPolygons > 0) {
        polygonBatchIds = new Uint16Array(numberOfPolygons);
        for (i = 0; i < numberOfPolygons; ++i) {
          polygonBatchIds[i] = id++;
        }
      }
      if (!defined(polylineBatchIds) && numberOfPolylines > 0) {
        polylineBatchIds = new Uint16Array(numberOfPolylines);
        for (i = 0; i < numberOfPolylines; ++i) {
          polylineBatchIds[i] = id++;
        }
      }
      if (!defined(pointBatchIds) && numberOfPoints > 0) {
        pointBatchIds = new Uint16Array(numberOfPoints);
        for (i = 0; i < numberOfPoints; ++i) {
          pointBatchIds[i] = id++;
        }
      }
    }

    return {
      polygons: polygonBatchIds,
      polylines: polylineBatchIds,
      points: pointBatchIds,
    };
  }

  var sizeOfUint32$8 = Uint32Array.BYTES_PER_ELEMENT;

  function initialize$8(content, arrayBuffer, byteOffset) {
    byteOffset = defaultValue(byteOffset, 0);

    var uint8Array = new Uint8Array(arrayBuffer);
    var view = new DataView(arrayBuffer);
    byteOffset += sizeOfUint32$8; // Skip magic number

    var version = view.getUint32(byteOffset, true);
    if (version !== 1) {
      throw new RuntimeError(
        "Only Vector tile version 1 is supported.  Version " +
          version +
          " is not."
      );
    }
    byteOffset += sizeOfUint32$8;

    var byteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;

    if (byteLength === 0) {
      content._readyPromise.resolve(content);
      return;
    }

    var featureTableJSONByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;

    if (featureTableJSONByteLength === 0) {
      throw new RuntimeError(
        "Feature table must have a byte length greater than zero"
      );
    }

    var featureTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;
    var batchTableJSONByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;
    var batchTableBinaryByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;
    var indicesByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;
    var positionByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;
    var polylinePositionByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;
    var pointsPositionByteLength = view.getUint32(byteOffset, true);
    byteOffset += sizeOfUint32$8;

    var featureTableString = getStringFromTypedArray(
      uint8Array,
      byteOffset,
      featureTableJSONByteLength
    );
    var featureTableJson = JSON.parse(featureTableString);
    byteOffset += featureTableJSONByteLength;

    var featureTableBinary = new Uint8Array(
      arrayBuffer,
      byteOffset,
      featureTableBinaryByteLength
    );
    byteOffset += featureTableBinaryByteLength;

    var batchTableJson;
    var batchTableBinary;
    if (batchTableJSONByteLength > 0) {
      // PERFORMANCE_IDEA: is it possible to allocate this on-demand?  Perhaps keep the
      // arraybuffer/string compressed in memory and then decompress it when it is first accessed.
      //
      // We could also make another request for it, but that would make the property set/get
      // API async, and would double the number of numbers in some cases.
      var batchTableString = getStringFromTypedArray(
        uint8Array,
        byteOffset,
        batchTableJSONByteLength
      );
      batchTableJson = JSON.parse(batchTableString);
      byteOffset += batchTableJSONByteLength;

      if (batchTableBinaryByteLength > 0) {
        // Has a batch table binary
        batchTableBinary = new Uint8Array(
          arrayBuffer,
          byteOffset,
          batchTableBinaryByteLength
        );
        // Copy the batchTableBinary section and let the underlying ArrayBuffer be freed
        batchTableBinary = new Uint8Array(batchTableBinary);
        byteOffset += batchTableBinaryByteLength;
      }
    }

    var numberOfPolygons = defaultValue(featureTableJson.POLYGONS_LENGTH, 0);
    var numberOfPolylines = defaultValue(featureTableJson.POLYLINES_LENGTH, 0);
    var numberOfPoints = defaultValue(featureTableJson.POINTS_LENGTH, 0);
    var totalPrimitives = numberOfPolygons + numberOfPolylines + numberOfPoints;

    var batchTable = new Cesium3DTileBatchTable(
      content,
      totalPrimitives,
      batchTableJson,
      batchTableBinary,
      createColorChangedCallback$2(content)
    );
    content._batchTable = batchTable;

    if (totalPrimitives === 0) {
      return;
    }

    var featureTable = new Cesium3DTileFeatureTable(
      featureTableJson,
      featureTableBinary
    );
    var region = featureTable.getGlobalProperty("REGION");
    if (!defined(region)) {
      throw new RuntimeError(
        "Feature table global property: REGION must be defined"
      );
    }
    var rectangle = Rectangle.unpack(region);
    var minHeight = region[4];
    var maxHeight = region[5];

    var modelMatrix = content._tile.computedTransform;

    var center = featureTable.getGlobalProperty(
      "RTC_CENTER",
      ComponentDatatype$1.FLOAT,
      3
    );
    if (defined(center)) {
      center = Cartesian3.unpack(center);
      Matrix4.multiplyByPoint(modelMatrix, center, center);
    } else {
      center = Rectangle.center(rectangle);
      center.height = CesiumMath.lerp(minHeight, maxHeight, 0.5);
      center = Ellipsoid.WGS84.cartographicToCartesian(center);
    }

    var batchIds = getBatchIds$1(featureTableJson, featureTableBinary);
    byteOffset += byteOffset % 4;

    if (numberOfPolygons > 0) {
      featureTable.featuresLength = numberOfPolygons;

      var polygonCounts = defaultValue(
        featureTable.getPropertyArray(
          "POLYGON_COUNTS",
          ComponentDatatype$1.UNSIGNED_INT,
          1
        ),
        featureTable.getPropertyArray(
          "POLYGON_COUNT",
          ComponentDatatype$1.UNSIGNED_INT,
          1
        ) // Workaround for old vector tilesets using the non-plural name
      );

      if (!defined(polygonCounts)) {
        throw new RuntimeError(
          "Feature table property: POLYGON_COUNTS must be defined when POLYGONS_LENGTH is greater than 0"
        );
      }

      var polygonIndexCounts = defaultValue(
        featureTable.getPropertyArray(
          "POLYGON_INDEX_COUNTS",
          ComponentDatatype$1.UNSIGNED_INT,
          1
        ),
        featureTable.getPropertyArray(
          "POLYGON_INDEX_COUNT",
          ComponentDatatype$1.UNSIGNED_INT,
          1
        ) // Workaround for old vector tilesets using the non-plural name
      );

      if (!defined(polygonIndexCounts)) {
        throw new RuntimeError(
          "Feature table property: POLYGON_INDEX_COUNTS must be defined when POLYGONS_LENGTH is greater than 0"
        );
      }

      // Use the counts array to determine how many position values we want. If we used the byte length then
      // zero padding values would be included and cause the delta zig-zag decoding to fail
      var numPolygonPositions = polygonCounts.reduce(function (total, count) {
        return total + count * 2;
      }, 0);

      var numPolygonIndices = polygonIndexCounts.reduce(function (total, count) {
        return total + count;
      }, 0);

      var indices = new Uint32Array(arrayBuffer, byteOffset, numPolygonIndices);
      byteOffset += indicesByteLength;

      var polygonPositions = new Uint16Array(
        arrayBuffer,
        byteOffset,
        numPolygonPositions
      );
      byteOffset += positionByteLength;

      var polygonMinimumHeights;
      var polygonMaximumHeights;
      if (
        defined(featureTableJson.POLYGON_MINIMUM_HEIGHTS) &&
        defined(featureTableJson.POLYGON_MAXIMUM_HEIGHTS)
      ) {
        polygonMinimumHeights = featureTable.getPropertyArray(
          "POLYGON_MINIMUM_HEIGHTS",
          ComponentDatatype$1.FLOAT,
          1
        );
        polygonMaximumHeights = featureTable.getPropertyArray(
          "POLYGON_MAXIMUM_HEIGHTS",
          ComponentDatatype$1.FLOAT,
          1
        );
      }

      content._polygons = new Vector3DTilePolygons({
        positions: polygonPositions,
        counts: polygonCounts,
        indexCounts: polygonIndexCounts,
        indices: indices,
        minimumHeight: minHeight,
        maximumHeight: maxHeight,
        polygonMinimumHeights: polygonMinimumHeights,
        polygonMaximumHeights: polygonMaximumHeights,
        center: center,
        rectangle: rectangle,
        boundingVolume: content.tile.boundingVolume.boundingVolume,
        batchTable: batchTable,
        batchIds: batchIds.polygons,
        modelMatrix: modelMatrix,
      });
    }

    if (numberOfPolylines > 0) {
      featureTable.featuresLength = numberOfPolylines;

      var polylineCounts = defaultValue(
        featureTable.getPropertyArray(
          "POLYLINE_COUNTS",
          ComponentDatatype$1.UNSIGNED_INT,
          1
        ),
        featureTable.getPropertyArray(
          "POLYLINE_COUNT",
          ComponentDatatype$1.UNSIGNED_INT,
          1
        ) // Workaround for old vector tilesets using the non-plural name
      );

      if (!defined(polylineCounts)) {
        throw new RuntimeError(
          "Feature table property: POLYLINE_COUNTS must be defined when POLYLINES_LENGTH is greater than 0"
        );
      }

      var widths = featureTable.getPropertyArray(
        "POLYLINE_WIDTHS",
        ComponentDatatype$1.UNSIGNED_SHORT,
        1
      );
      if (!defined(widths)) {
        widths = new Uint16Array(numberOfPolylines);
        for (var i = 0; i < numberOfPolylines; ++i) {
          widths[i] = 2.0;
        }
      }

      // Use the counts array to determine how many position values we want. If we used the byte length then
      // zero padding values would be included and cause the delta zig-zag decoding to fail
      var numPolylinePositions = polylineCounts.reduce(function (total, count) {
        return total + count * 3;
      }, 0);
      var polylinePositions = new Uint16Array(
        arrayBuffer,
        byteOffset,
        numPolylinePositions
      );
      byteOffset += polylinePositionByteLength;

      content._polylines = new Vector3DTilePolylines({
        positions: polylinePositions,
        widths: widths,
        counts: polylineCounts,
        batchIds: batchIds.polylines,
        minimumHeight: minHeight,
        maximumHeight: maxHeight,
        center: center,
        rectangle: rectangle,
        boundingVolume: content.tile.boundingVolume.boundingVolume,
        batchTable: batchTable,
      });
    }

    if (numberOfPoints > 0) {
      var pointPositions = new Uint16Array(
        arrayBuffer,
        byteOffset,
        numberOfPoints * 3
      );
      byteOffset += pointsPositionByteLength;
      content._points = new Vector3DTilePoints({
        positions: pointPositions,
        batchIds: batchIds.points,
        minimumHeight: minHeight,
        maximumHeight: maxHeight,
        rectangle: rectangle,
        batchTable: batchTable,
      });
    }
  }

  function createFeatures$4(content) {
    var featuresLength = content.featuresLength;
    if (!defined(content._features) && featuresLength > 0) {
      var features = new Array(featuresLength);

      if (defined(content._polygons)) {
        content._polygons.createFeatures(content, features);
      }
      if (defined(content._polylines)) {
        content._polylines.createFeatures(content, features);
      }
      if (defined(content._points)) {
        content._points.createFeatures(content, features);
      }
      content._features = features;
    }
  }

  Vector3DTileContent.prototype.hasProperty = function (batchId, name) {
    return this._batchTable.hasProperty(batchId, name);
  };

  Vector3DTileContent.prototype.getFeature = function (batchId) {
    //>>includeStart('debug', pragmas.debug);
    var featuresLength = this.featuresLength;
    if (!defined(batchId) || batchId < 0 || batchId >= featuresLength) {
      throw new DeveloperError(
        "batchId is required and between zero and featuresLength - 1 (" +
          (featuresLength - 1) +
          ")."
      );
    }
    //>>includeEnd('debug');

    createFeatures$4(this);
    return this._features[batchId];
  };

  Vector3DTileContent.prototype.applyDebugSettings = function (enabled, color) {
    if (defined(this._polygons)) {
      this._polygons.applyDebugSettings(enabled, color);
    }
    if (defined(this._polylines)) {
      this._polylines.applyDebugSettings(enabled, color);
    }
    if (defined(this._points)) {
      this._points.applyDebugSettings(enabled, color);
    }
  };

  Vector3DTileContent.prototype.applyStyle = function (style) {
    createFeatures$4(this);
    if (defined(this._polygons)) {
      this._polygons.applyStyle(style, this._features);
    }
    if (defined(this._polylines)) {
      this._polylines.applyStyle(style, this._features);
    }
    if (defined(this._points)) {
      this._points.applyStyle(style, this._features);
    }
  };

  Vector3DTileContent.prototype.update = function (tileset, frameState) {
    var ready = true;
    if (defined(this._polygons)) {
      this._polygons.classificationType = this._tileset.classificationType;
      this._polygons.debugWireframe = this._tileset.debugWireframe;
      this._polygons.update(frameState);
      ready = ready && this._polygons._ready;
    }
    if (defined(this._polylines)) {
      this._polylines.update(frameState);
      ready = ready && this._polylines._ready;
    }
    if (defined(this._points)) {
      this._points.update(frameState);
      ready = ready && this._points._ready;
    }
    if (defined(this._batchTable) && ready) {
      this._batchTable.update(tileset, frameState);
    }

    if (!defined(this._contentReadyPromise)) {
      var pointsPromise = defined(this._points)
        ? this._points.readyPromise
        : undefined;
      var polygonPromise = defined(this._polygons)
        ? this._polygons.readyPromise
        : undefined;
      var polylinePromise = defined(this._polylines)
        ? this._polylines.readyPromise
        : undefined;

      var that = this;
      this._contentReadyPromise = when
        .all([pointsPromise, polygonPromise, polylinePromise])
        .then(function () {
          that._readyPromise.resolve(that);
        });
    }
  };

  Vector3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Vector3DTileContent.prototype.destroy = function () {
    this._polygons = this._polygons && this._polygons.destroy();
    this._polylines = this._polylines && this._polylines.destroy();
    this._points = this._points && this._points.destroy();
    this._batchTable = this._batchTable && this._batchTable.destroy();
    return destroyObject(this);
  };

  /**
   * Maps a tile's magic field in its header to a new content object for the tile's payload.
   *
   * @private
   */
  var Cesium3DTileContentFactory = {
    b3dm: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      return new Batched3DModel3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset
      );
    },
    pnts: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      return new PointCloud3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset
      );
    },
    i3dm: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      return new Instanced3DModel3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset
      );
    },
    cmpt: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      // Send in the factory in order to avoid a cyclical dependency
      return new Composite3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset,
        Cesium3DTileContentFactory
      );
    },
    json: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      return new Tileset3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset
      );
    },
    geom: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      return new Geometry3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset
      );
    },
    vctr: function (tileset, tile, resource, arrayBuffer, byteOffset) {
      return new Vector3DTileContent(
        tileset,
        tile,
        resource,
        arrayBuffer,
        byteOffset
      );
    },
  };

  /**
   * @private
   */
  var Cesium3DTileContentState = {
    UNLOADED: 0, // Has never been requested
    LOADING: 1, // Is waiting on a pending request
    PROCESSING: 2, // Request received.  Contents are being processed for rendering.  Depending on the content, it might make its own requests for external data.
    READY: 3, // Ready to render.
    EXPIRED: 4, // Is expired and will be unloaded once new content is loaded.
    FAILED: 5, // Request failed.
  };
  var Cesium3DTileContentState$1 = Object.freeze(Cesium3DTileContentState);

  /**
   * Hint defining optimization support for a 3D tile
   *
   * @enum {Number}
   *
   * @private
   */
  var Cesium3DTileOptimizationHint = {
    NOT_COMPUTED: -1,
    USE_OPTIMIZATION: 1,
    SKIP_OPTIMIZATION: 0,
  };
  var Cesium3DTileOptimizationHint$1 = Object.freeze(Cesium3DTileOptimizationHint);

  /**
   * Traversal that loads all leaves that intersect the camera frustum.
   * Used to determine ray-tileset intersections during a pickFromRayMostDetailed call.
   *
   * @private
   */
  function Cesium3DTilesetMostDetailedTraversal() {}

  var traversal = {
    stack: new ManagedArray(),
    stackMaximumLength: 0,
  };

  Cesium3DTilesetMostDetailedTraversal.selectTiles = function (
    tileset,
    frameState
  ) {
    tileset._selectedTiles.length = 0;
    tileset._requestedTiles.length = 0;
    tileset._hasMixedContent = false;

    var ready = true;

    var root = tileset.root;
    root.updateVisibility(frameState);

    if (!isVisible(root)) {
      return ready;
    }

    var stack = traversal.stack;
    stack.push(tileset.root);

    while (stack.length > 0) {
      traversal.stackMaximumLength = Math.max(
        traversal.stackMaximumLength,
        stack.length
      );

      var tile = stack.pop();
      var add = tile.refine === Cesium3DTileRefine$1.ADD;
      var replace = tile.refine === Cesium3DTileRefine$1.REPLACE;
      var traverse = canTraverse(tileset, tile);

      if (traverse) {
        updateAndPushChildren(tileset, tile, stack, frameState);
      }

      if (add || (replace && !traverse)) {
        loadTile(tileset, tile);
        touchTile(tileset, tile, frameState);
        selectDesiredTile(tileset, tile, frameState);

        if (!hasEmptyContent(tile) && !tile.contentAvailable) {
          ready = false;
        }
      }

      visitTile(tileset);
    }

    traversal.stack.trim(traversal.stackMaximumLength);

    return ready;
  };

  function isVisible(tile) {
    return tile._visible && tile._inRequestVolume;
  }

  function hasEmptyContent(tile) {
    return tile.hasEmptyContent || tile.hasTilesetContent;
  }

  function hasUnloadedContent(tile) {
    return !hasEmptyContent(tile) && tile.contentUnloaded;
  }

  function canTraverse(tileset, tile) {
    if (tile.children.length === 0) {
      return false;
    }

    if (tile.hasTilesetContent) {
      // Traverse external tileset to visit its root tile
      // Don't traverse if the subtree is expired because it will be destroyed
      return !tile.contentExpired;
    }

    if (tile.hasEmptyContent) {
      return true;
    }

    return true; // Keep traversing until a leave is hit
  }

  function updateAndPushChildren(tileset, tile, stack, frameState) {
    var children = tile.children;
    var length = children.length;

    for (var i = 0; i < length; ++i) {
      var child = children[i];
      child.updateVisibility(frameState);
      if (isVisible(child)) {
        stack.push(child);
      }
    }
  }

  function loadTile(tileset, tile) {
    if (hasUnloadedContent(tile) || tile.contentExpired) {
      tile._priority = 0.0; // Highest priority
      tileset._requestedTiles.push(tile);
    }
  }

  function touchTile(tileset, tile, frameState) {
    if (tile._touchedFrame === frameState.frameNumber) {
      // Prevents another pass from touching the frame again
      return;
    }
    tileset._cache.touch(tile);
    tile._touchedFrame = frameState.frameNumber;
  }

  function visitTile(tileset) {
    ++tileset.statistics.visited;
  }

  function selectDesiredTile(tileset, tile, frameState) {
    if (
      tile.contentAvailable &&
      tile.contentVisibility(frameState) !== Intersect$1.OUTSIDE
    ) {
      tileset._selectedTiles.push(tile);
    }
  }

  /**
   * @private
   */
  function Cesium3DTilesetTraversal() {}

  function isVisible$1(tile) {
    return tile._visible && tile._inRequestVolume;
  }

  var traversal$1 = {
    stack: new ManagedArray(),
    stackMaximumLength: 0,
  };

  var emptyTraversal = {
    stack: new ManagedArray(),
    stackMaximumLength: 0,
  };

  var descendantTraversal = {
    stack: new ManagedArray(),
    stackMaximumLength: 0,
  };

  var selectionTraversal = {
    stack: new ManagedArray(),
    stackMaximumLength: 0,
    ancestorStack: new ManagedArray(),
    ancestorStackMaximumLength: 0,
  };

  var descendantSelectionDepth = 2;

  Cesium3DTilesetTraversal.selectTiles = function (tileset, frameState) {
    tileset._requestedTiles.length = 0;

    if (tileset.debugFreezeFrame) {
      return;
    }

    tileset._selectedTiles.length = 0;
    tileset._selectedTilesToStyle.length = 0;
    tileset._emptyTiles.length = 0;
    tileset._hasMixedContent = false;

    var root = tileset.root;
    updateTile(tileset, root, frameState);

    // The root tile is not visible
    if (!isVisible$1(root)) {
      return;
    }

    // The tileset doesn't meet the SSE requirement, therefore the tree does not need to be rendered
    if (
      root.getScreenSpaceError(frameState, true) <=
      tileset._maximumScreenSpaceError
    ) {
      return;
    }

    if (!skipLevelOfDetail(tileset)) {
      executeBaseTraversal(tileset, root, frameState);
    } else if (tileset.immediatelyLoadDesiredLevelOfDetail) {
      executeSkipTraversal(tileset, root, frameState);
    } else {
      executeBaseAndSkipTraversal(tileset, root, frameState);
    }

    traversal$1.stack.trim(traversal$1.stackMaximumLength);
    emptyTraversal.stack.trim(emptyTraversal.stackMaximumLength);
    descendantTraversal.stack.trim(descendantTraversal.stackMaximumLength);
    selectionTraversal.stack.trim(selectionTraversal.stackMaximumLength);
    selectionTraversal.ancestorStack.trim(
      selectionTraversal.ancestorStackMaximumLength
    );

    // Update the priority for any requests found during traversal
    // Update after traversal so that min and max values can be used to normalize priority values
    var requestedTiles = tileset._requestedTiles;
    var length = requestedTiles.length;
    for (var i = 0; i < length; ++i) {
      requestedTiles[i].updatePriority();
    }
  };

  function executeBaseTraversal(tileset, root, frameState) {
    var baseScreenSpaceError = tileset._maximumScreenSpaceError;
    var maximumScreenSpaceError = tileset._maximumScreenSpaceError;
    executeTraversal(
      tileset,
      root,
      baseScreenSpaceError,
      maximumScreenSpaceError,
      frameState
    );
  }

  function executeSkipTraversal(tileset, root, frameState) {
    var baseScreenSpaceError = Number.MAX_VALUE;
    var maximumScreenSpaceError = tileset._maximumScreenSpaceError;
    executeTraversal(
      tileset,
      root,
      baseScreenSpaceError,
      maximumScreenSpaceError,
      frameState
    );
    traverseAndSelect(tileset, root, frameState);
  }

  function executeBaseAndSkipTraversal(tileset, root, frameState) {
    var baseScreenSpaceError = Math.max(
      tileset.baseScreenSpaceError,
      tileset.maximumScreenSpaceError
    );
    var maximumScreenSpaceError = tileset.maximumScreenSpaceError;
    executeTraversal(
      tileset,
      root,
      baseScreenSpaceError,
      maximumScreenSpaceError,
      frameState
    );
    traverseAndSelect(tileset, root, frameState);
  }

  function skipLevelOfDetail(tileset) {
    return tileset._skipLevelOfDetail;
  }

  function addEmptyTile(tileset, tile) {
    tileset._emptyTiles.push(tile);
  }

  function selectTile(tileset, tile, frameState) {
    if (tile.contentVisibility(frameState) !== Intersect$1.OUTSIDE) {
      var tileContent = tile.content;
      if (tileContent.featurePropertiesDirty) {
        // A feature's property in this tile changed, the tile needs to be re-styled.
        tileContent.featurePropertiesDirty = false;
        tile.lastStyleTime = 0; // Force applying the style to this tile
        tileset._selectedTilesToStyle.push(tile);
      } else if (tile._selectedFrame < frameState.frameNumber - 1) {
        // Tile is newly selected; it is selected this frame, but was not selected last frame.
        tileset._selectedTilesToStyle.push(tile);
      }
      tile._selectedFrame = frameState.frameNumber;
      tileset._selectedTiles.push(tile);
    }
  }

  function selectDescendants(tileset, root, frameState) {
    var stack = descendantTraversal.stack;
    stack.push(root);
    while (stack.length > 0) {
      descendantTraversal.stackMaximumLength = Math.max(
        descendantTraversal.stackMaximumLength,
        stack.length
      );
      var tile = stack.pop();
      var children = tile.children;
      var childrenLength = children.length;
      for (var i = 0; i < childrenLength; ++i) {
        var child = children[i];
        if (isVisible$1(child)) {
          if (child.contentAvailable) {
            updateTile(tileset, child, frameState);
            touchTile$1(tileset, child, frameState);
            selectTile(tileset, child, frameState);
          } else if (child._depth - root._depth < descendantSelectionDepth) {
            // Continue traversing, but not too far
            stack.push(child);
          }
        }
      }
    }
  }

  function selectDesiredTile$1(tileset, tile, frameState) {
    if (!skipLevelOfDetail(tileset)) {
      if (tile.contentAvailable) {
        // The tile can be selected right away and does not require traverseAndSelect
        selectTile(tileset, tile, frameState);
      }
      return;
    }

    // If this tile is not loaded attempt to select its ancestor instead
    var loadedTile = tile.contentAvailable
      ? tile
      : tile._ancestorWithContentAvailable;
    if (defined(loadedTile)) {
      // Tiles will actually be selected in traverseAndSelect
      loadedTile._shouldSelect = true;
    } else {
      // If no ancestors are ready traverse down and select tiles to minimize empty regions.
      // This happens often for immediatelyLoadDesiredLevelOfDetail where parent tiles are not necessarily loaded before zooming out.
      selectDescendants(tileset, tile, frameState);
    }
  }

  function visitTile$1(tileset, tile, frameState) {
    ++tileset._statistics.visited;
    tile._visitedFrame = frameState.frameNumber;
  }

  function touchTile$1(tileset, tile, frameState) {
    if (tile._touchedFrame === frameState.frameNumber) {
      // Prevents another pass from touching the frame again
      return;
    }
    tileset._cache.touch(tile);
    tile._touchedFrame = frameState.frameNumber;
  }

  function updateMinimumMaximumPriority(tileset, tile) {
    tileset._maximumPriority.distance = Math.max(
      tile._priorityHolder._distanceToCamera,
      tileset._maximumPriority.distance
    );
    tileset._minimumPriority.distance = Math.min(
      tile._priorityHolder._distanceToCamera,
      tileset._minimumPriority.distance
    );
    tileset._maximumPriority.depth = Math.max(
      tile._depth,
      tileset._maximumPriority.depth
    );
    tileset._minimumPriority.depth = Math.min(
      tile._depth,
      tileset._minimumPriority.depth
    );
    tileset._maximumPriority.foveatedFactor = Math.max(
      tile._priorityHolder._foveatedFactor,
      tileset._maximumPriority.foveatedFactor
    );
    tileset._minimumPriority.foveatedFactor = Math.min(
      tile._priorityHolder._foveatedFactor,
      tileset._minimumPriority.foveatedFactor
    );
    tileset._maximumPriority.reverseScreenSpaceError = Math.max(
      tile._priorityReverseScreenSpaceError,
      tileset._maximumPriority.reverseScreenSpaceError
    );
    tileset._minimumPriority.reverseScreenSpaceError = Math.min(
      tile._priorityReverseScreenSpaceError,
      tileset._minimumPriority.reverseScreenSpaceError
    );
  }

  function isOnScreenLongEnough(tileset, tile, frameState) {
    // Prevent unnecessary loads while camera is moving by getting the ratio of travel distance to tile size.
    if (!tileset._cullRequestsWhileMoving) {
      return true;
    }

    var sphere = tile.boundingSphere;
    var diameter = Math.max(sphere.radius * 2.0, 1.0);

    var camera = frameState.camera;
    var deltaMagnitude =
      camera.positionWCDeltaMagnitude !== 0.0
        ? camera.positionWCDeltaMagnitude
        : camera.positionWCDeltaMagnitudeLastFrame;
    var movementRatio =
      (tileset.cullRequestsWhileMovingMultiplier * deltaMagnitude) / diameter; // How do n frames of this movement compare to the tile's physical size.
    return movementRatio < 1.0;
  }

  function loadTile$1(tileset, tile, frameState) {
    if (
      tile._requestedFrame === frameState.frameNumber ||
      (!hasUnloadedContent$1(tile) && !tile.contentExpired)
    ) {
      return;
    }

    if (!isOnScreenLongEnough(tileset, tile, frameState)) {
      return;
    }

    var cameraHasNotStoppedMovingLongEnough =
      frameState.camera.timeSinceMoved < tileset.foveatedTimeDelay;
    if (tile.priorityDeferred && cameraHasNotStoppedMovingLongEnough) {
      return;
    }

    tile._requestedFrame = frameState.frameNumber;
    tileset._requestedTiles.push(tile);
  }

  function updateVisibility(tileset, tile, frameState) {
    if (tile._updatedVisibilityFrame === tileset._updatedVisibilityFrame) {
      // Return early if visibility has already been checked during the traversal.
      // The visibility may have already been checked if the cullWithChildrenBounds optimization is used.
      return;
    }

    tile.updateVisibility(frameState);
    tile._updatedVisibilityFrame = tileset._updatedVisibilityFrame;
  }

  function anyChildrenVisible(tileset, tile, frameState) {
    var anyVisible = false;
    var children = tile.children;
    var length = children.length;
    for (var i = 0; i < length; ++i) {
      var child = children[i];
      updateVisibility(tileset, child, frameState);
      anyVisible = anyVisible || isVisible$1(child);
    }
    return anyVisible;
  }

  function meetsScreenSpaceErrorEarly(tileset, tile, frameState) {
    var parent = tile.parent;
    if (
      !defined(parent) ||
      parent.hasTilesetContent ||
      parent.refine !== Cesium3DTileRefine$1.ADD
    ) {
      return false;
    }

    // Use parent's geometric error with child's box to see if the tile already meet the SSE
    return (
      tile.getScreenSpaceError(frameState, true) <=
      tileset._maximumScreenSpaceError
    );
  }

  function updateTileVisibility(tileset, tile, frameState) {
    updateVisibility(tileset, tile, frameState);

    if (!isVisible$1(tile)) {
      return;
    }

    var hasChildren = tile.children.length > 0;
    if (tile.hasTilesetContent && hasChildren) {
      // Use the root tile's visibility instead of this tile's visibility.
      // The root tile may be culled by the children bounds optimization in which
      // case this tile should also be culled.
      var child = tile.children[0];
      updateTileVisibility(tileset, child, frameState);
      tile._visible = child._visible;
      return;
    }

    if (meetsScreenSpaceErrorEarly(tileset, tile, frameState)) {
      tile._visible = false;
      return;
    }

    // Optimization - if none of the tile's children are visible then this tile isn't visible
    var replace = tile.refine === Cesium3DTileRefine$1.REPLACE;
    var useOptimization =
      tile._optimChildrenWithinParent ===
      Cesium3DTileOptimizationHint$1.USE_OPTIMIZATION;
    if (replace && useOptimization && hasChildren) {
      if (!anyChildrenVisible(tileset, tile, frameState)) {
        ++tileset._statistics.numberOfTilesCulledWithChildrenUnion;
        tile._visible = false;
        return;
      }
    }
  }

  function updateTile(tileset, tile, frameState) {
    // Reset some of the tile's flags and re-evaluate visibility
    updateTileVisibility(tileset, tile, frameState);
    tile.updateExpiration();

    // Request priority
    tile._wasMinPriorityChild = false;
    tile._priorityHolder = tile;
    updateMinimumMaximumPriority(tileset, tile);

    // SkipLOD
    tile._shouldSelect = false;
    tile._finalResolution = true;
  }

  function updateTileAncestorContentLinks(tile, frameState) {
    tile._ancestorWithContent = undefined;
    tile._ancestorWithContentAvailable = undefined;

    var parent = tile.parent;
    if (defined(parent)) {
      // ancestorWithContent is an ancestor that has content or has the potential to have
      // content. Used in conjunction with tileset.skipLevels to know when to skip a tile.
      // ancestorWithContentAvailable is an ancestor that is rendered if a desired tile is not loaded.
      var hasContent =
        !hasUnloadedContent$1(parent) ||
        parent._requestedFrame === frameState.frameNumber;
      tile._ancestorWithContent = hasContent
        ? parent
        : parent._ancestorWithContent;
      tile._ancestorWithContentAvailable = parent.contentAvailable
        ? parent
        : parent._ancestorWithContentAvailable; // Links a descendant up to its contentAvailable ancestor as the traversal progresses.
    }
  }

  function hasEmptyContent$1(tile) {
    return tile.hasEmptyContent || tile.hasTilesetContent;
  }

  function hasUnloadedContent$1(tile) {
    return !hasEmptyContent$1(tile) && tile.contentUnloaded;
  }

  function reachedSkippingThreshold(tileset, tile) {
    var ancestor = tile._ancestorWithContent;
    return (
      !tileset.immediatelyLoadDesiredLevelOfDetail &&
      (tile._priorityProgressiveResolutionScreenSpaceErrorLeaf ||
        (defined(ancestor) &&
          tile._screenSpaceError <
            ancestor._screenSpaceError / tileset.skipScreenSpaceErrorFactor &&
          tile._depth > ancestor._depth + tileset.skipLevels))
    );
  }

  function sortChildrenByDistanceToCamera(a, b) {
    // Sort by farthest child first since this is going on a stack
    if (b._distanceToCamera === 0 && a._distanceToCamera === 0) {
      return b._centerZDepth - a._centerZDepth;
    }

    return b._distanceToCamera - a._distanceToCamera;
  }

  function updateAndPushChildren$1(tileset, tile, stack, frameState) {
    var i;
    var replace = tile.refine === Cesium3DTileRefine$1.REPLACE;
    var children = tile.children;
    var length = children.length;

    for (i = 0; i < length; ++i) {
      updateTile(tileset, children[i], frameState);
    }

    // Sort by distance to take advantage of early Z and reduce artifacts for skipLevelOfDetail
    children.sort(sortChildrenByDistanceToCamera);

    // For traditional replacement refinement only refine if all children are loaded.
    // Empty tiles are exempt since it looks better if children stream in as they are loaded to fill the empty space.
    var checkRefines =
      !skipLevelOfDetail(tileset) && replace && !hasEmptyContent$1(tile);
    var refines = true;

    var anyChildrenVisible = false;

    // Determining min child
    var minIndex = -1;
    var minimumPriority = Number.MAX_VALUE;

    var child;
    for (i = 0; i < length; ++i) {
      child = children[i];
      if (isVisible$1(child)) {
        stack.push(child);
        if (child._foveatedFactor < minimumPriority) {
          minIndex = i;
          minimumPriority = child._foveatedFactor;
        }
        anyChildrenVisible = true;
      } else if (checkRefines || tileset.loadSiblings) {
        // Keep non-visible children loaded since they are still needed before the parent can refine.
        // Or loadSiblings is true so always load tiles regardless of visibility.
        if (child._foveatedFactor < minimumPriority) {
          minIndex = i;
          minimumPriority = child._foveatedFactor;
        }
        loadTile$1(tileset, child, frameState);
        touchTile$1(tileset, child, frameState);
      }
      if (checkRefines) {
        var childRefines;
        if (!child._inRequestVolume) {
          childRefines = false;
        } else if (hasEmptyContent$1(child)) {
          childRefines = executeEmptyTraversal(tileset, child, frameState);
        } else {
          childRefines = child.contentAvailable;
        }
        refines = refines && childRefines;
      }
    }

    if (!anyChildrenVisible) {
      refines = false;
    }

    if (minIndex !== -1 && !skipLevelOfDetail(tileset) && replace) {
      // An ancestor will hold the _foveatedFactor and _distanceToCamera for descendants between itself and its highest priority descendant. Siblings of a min children along the way use this ancestor as their priority holder as well.
      // Priority of all tiles that refer to the _foveatedFactor and _distanceToCamera stored in the common ancestor will be differentiated based on their _depth.
      var minPriorityChild = children[minIndex];
      minPriorityChild._wasMinPriorityChild = true;
      var priorityHolder =
        (tile._wasMinPriorityChild || tile === tileset.root) &&
        minimumPriority <= tile._priorityHolder._foveatedFactor
          ? tile._priorityHolder
          : tile; // This is where priority dependency chains are wired up or started anew.
      priorityHolder._foveatedFactor = Math.min(
        minPriorityChild._foveatedFactor,
        priorityHolder._foveatedFactor
      );
      priorityHolder._distanceToCamera = Math.min(
        minPriorityChild._distanceToCamera,
        priorityHolder._distanceToCamera
      );

      for (i = 0; i < length; ++i) {
        child = children[i];
        child._priorityHolder = priorityHolder;
      }
    }

    return refines;
  }

  function inBaseTraversal(tileset, tile, baseScreenSpaceError) {
    if (!skipLevelOfDetail(tileset)) {
      return true;
    }
    if (tileset.immediatelyLoadDesiredLevelOfDetail) {
      return false;
    }
    if (!defined(tile._ancestorWithContent)) {
      // Include root or near-root tiles in the base traversal so there is something to select up to
      return true;
    }
    if (tile._screenSpaceError === 0.0) {
      // If a leaf, use parent's SSE
      return tile.parent._screenSpaceError > baseScreenSpaceError;
    }
    return tile._screenSpaceError > baseScreenSpaceError;
  }

  function canTraverse$1(tileset, tile) {
    if (tile.children.length === 0) {
      return false;
    }
    if (tile.hasTilesetContent) {
      // Traverse external tileset to visit its root tile
      // Don't traverse if the subtree is expired because it will be destroyed
      return !tile.contentExpired;
    }
    return tile._screenSpaceError > tileset._maximumScreenSpaceError;
  }

  function executeTraversal(
    tileset,
    root,
    baseScreenSpaceError,
    maximumScreenSpaceError,
    frameState
  ) {
    // Depth-first traversal that traverses all visible tiles and marks tiles for selection.
    // If skipLevelOfDetail is off then a tile does not refine until all children are loaded.
    // This is the traditional replacement refinement approach and is called the base traversal.
    // Tiles that have a greater screen space error than the base screen space error are part of the base traversal,
    // all other tiles are part of the skip traversal. The skip traversal allows for skipping levels of the tree
    // and rendering children and parent tiles simultaneously.
    var stack = traversal$1.stack;
    stack.push(root);

    while (stack.length > 0) {
      traversal$1.stackMaximumLength = Math.max(
        traversal$1.stackMaximumLength,
        stack.length
      );

      var tile = stack.pop();

      updateTileAncestorContentLinks(tile, frameState);
      var baseTraversal = inBaseTraversal(tileset, tile, baseScreenSpaceError);
      var add = tile.refine === Cesium3DTileRefine$1.ADD;
      var replace = tile.refine === Cesium3DTileRefine$1.REPLACE;
      var parent = tile.parent;
      var parentRefines = !defined(parent) || parent._refines;
      var refines = false;

      if (canTraverse$1(tileset, tile)) {
        refines =
          updateAndPushChildren$1(tileset, tile, stack, frameState) &&
          parentRefines;
      }

      var stoppedRefining = !refines && parentRefines;

      if (hasEmptyContent$1(tile)) {
        // Add empty tile just to show its debug bounding volume
        // If the tile has tileset content load the external tileset
        // If the tile cannot refine further select its nearest loaded ancestor
        addEmptyTile(tileset, tile);
        loadTile$1(tileset, tile, frameState);
        if (stoppedRefining) {
          selectDesiredTile$1(tileset, tile, frameState);
        }
      } else if (add) {
        // Additive tiles are always loaded and selected
        selectDesiredTile$1(tileset, tile, frameState);
        loadTile$1(tileset, tile, frameState);
      } else if (replace) {
        if (baseTraversal) {
          // Always load tiles in the base traversal
          // Select tiles that can't refine further
          loadTile$1(tileset, tile, frameState);
          if (stoppedRefining) {
            selectDesiredTile$1(tileset, tile, frameState);
          }
        } else if (stoppedRefining) {
          // In skip traversal, load and select tiles that can't refine further
          selectDesiredTile$1(tileset, tile, frameState);
          loadTile$1(tileset, tile, frameState);
        } else if (reachedSkippingThreshold(tileset, tile)) {
          // In skip traversal, load tiles that aren't skipped. In practice roughly half the tiles stay unloaded.
          loadTile$1(tileset, tile, frameState);
        }
      }

      visitTile$1(tileset, tile, frameState);
      touchTile$1(tileset, tile, frameState);
      tile._refines = refines;
    }
  }

  function executeEmptyTraversal(tileset, root, frameState) {
    // Depth-first traversal that checks if all nearest descendants with content are loaded. Ignores visibility.
    var allDescendantsLoaded = true;
    var stack = emptyTraversal.stack;
    stack.push(root);

    while (stack.length > 0) {
      emptyTraversal.stackMaximumLength = Math.max(
        emptyTraversal.stackMaximumLength,
        stack.length
      );

      var tile = stack.pop();
      var children = tile.children;
      var childrenLength = children.length;

      // Only traverse if the tile is empty - traversal stop at descendants with content
      var emptyContent = hasEmptyContent$1(tile);
      var traverse = emptyContent && canTraverse$1(tileset, tile);
      var emptyLeaf = emptyContent && tile.children.length === 0;

      // Traversal stops but the tile does not have content yet
      // There will be holes if the parent tries to refine to its children, so don't refine
      // One exception: a parent may refine even if one of its descendants is an empty leaf
      if (!traverse && !tile.contentAvailable && !emptyLeaf) {
        allDescendantsLoaded = false;
      }

      updateTile(tileset, tile, frameState);
      if (!isVisible$1(tile)) {
        // Load tiles that aren't visible since they are still needed for the parent to refine
        loadTile$1(tileset, tile, frameState);
        touchTile$1(tileset, tile, frameState);
      }

      if (traverse) {
        for (var i = 0; i < childrenLength; ++i) {
          var child = children[i];
          stack.push(child);
        }
      }
    }

    return allDescendantsLoaded;
  }

  /**
   * Traverse the tree and check if their selected frame is the current frame. If so, add it to a selection queue.
   * This is a preorder traversal so children tiles are selected before ancestor tiles.
   *
   * The reason for the preorder traversal is so that tiles can easily be marked with their
   * selection depth. A tile's _selectionDepth is its depth in the tree where all non-selected tiles are removed.
   * This property is important for use in the stencil test because we want to render deeper tiles on top of their
   * ancestors. If a tileset is very deep, the depth is unlikely to fit into the stencil buffer.
   *
   * We want to select children before their ancestors because there is no guarantee on the relationship between
   * the children's z-depth and the ancestor's z-depth. We cannot rely on Z because we want the child to appear on top
   * of ancestor regardless of true depth. The stencil tests used require children to be drawn first.
   *
   * NOTE: 3D Tiles uses 3 bits from the stencil buffer meaning this will not work when there is a chain of
   * selected tiles that is deeper than 7. This is not very likely.
   * @private
   */
  function traverseAndSelect(tileset, root, frameState) {
    var stack = selectionTraversal.stack;
    var ancestorStack = selectionTraversal.ancestorStack;
    var lastAncestor;

    stack.push(root);

    while (stack.length > 0 || ancestorStack.length > 0) {
      selectionTraversal.stackMaximumLength = Math.max(
        selectionTraversal.stackMaximumLength,
        stack.length
      );
      selectionTraversal.ancestorStackMaximumLength = Math.max(
        selectionTraversal.ancestorStackMaximumLength,
        ancestorStack.length
      );

      if (ancestorStack.length > 0) {
        var waitingTile = ancestorStack.peek();
        if (waitingTile._stackLength === stack.length) {
          ancestorStack.pop();
          if (waitingTile !== lastAncestor) {
            waitingTile._finalResolution = false;
          }
          selectTile(tileset, waitingTile, frameState);
          continue;
        }
      }

      var tile = stack.pop();
      if (!defined(tile)) {
        // stack is empty but ancestorStack isn't
        continue;
      }

      var add = tile.refine === Cesium3DTileRefine$1.ADD;
      var shouldSelect = tile._shouldSelect;
      var children = tile.children;
      var childrenLength = children.length;
      var traverse = canTraverse$1(tileset, tile);

      if (shouldSelect) {
        if (add) {
          selectTile(tileset, tile, frameState);
        } else {
          tile._selectionDepth = ancestorStack.length;
          if (tile._selectionDepth > 0) {
            tileset._hasMixedContent = true;
          }
          lastAncestor = tile;
          if (!traverse) {
            selectTile(tileset, tile, frameState);
            continue;
          }
          ancestorStack.push(tile);
          tile._stackLength = stack.length;
        }
      }

      if (traverse) {
        for (var i = 0; i < childrenLength; ++i) {
          var child = children[i];
          if (isVisible$1(child)) {
            stack.push(child);
          }
        }
      }
    }
  }

  /**
   * The pass in which a 3D Tileset is updated.
   *
   * @private
   */
  var Cesium3DTilePass = {
    RENDER: 0,
    PICK: 1,
    SHADOW: 2,
    PRELOAD: 3,
    PRELOAD_FLIGHT: 4,
    REQUEST_RENDER_MODE_DEFER_CHECK: 5,
    MOST_DETAILED_PRELOAD: 6,
    MOST_DETAILED_PICK: 7,
    NUMBER_OF_PASSES: 8,
  };

  var passOptions = new Array(Cesium3DTilePass.NUMBER_OF_PASSES);

  passOptions[Cesium3DTilePass.RENDER] = Object.freeze({
    traversal: Cesium3DTilesetTraversal,
    isRender: true,
    requestTiles: true,
    ignoreCommands: false,
  });

  passOptions[Cesium3DTilePass.PICK] = Object.freeze({
    traversal: Cesium3DTilesetTraversal,
    isRender: false,
    requestTiles: false,
    ignoreCommands: false,
  });

  passOptions[Cesium3DTilePass.SHADOW] = Object.freeze({
    traversal: Cesium3DTilesetTraversal,
    isRender: false,
    requestTiles: true,
    ignoreCommands: false,
  });

  passOptions[Cesium3DTilePass.PRELOAD] = Object.freeze({
    traversal: Cesium3DTilesetTraversal,
    isRender: false,
    requestTiles: true,
    ignoreCommands: true,
  });

  passOptions[Cesium3DTilePass.PRELOAD_FLIGHT] = Object.freeze({
    traversal: Cesium3DTilesetTraversal,
    isRender: false,
    requestTiles: true,
    ignoreCommands: true,
  });

  passOptions[Cesium3DTilePass.REQUEST_RENDER_MODE_DEFER_CHECK] = Object.freeze({
    traversal: Cesium3DTilesetTraversal,
    isRender: false,
    requestTiles: true,
    ignoreCommands: true,
  });

  passOptions[Cesium3DTilePass.MOST_DETAILED_PRELOAD] = Object.freeze({
    traversal: Cesium3DTilesetMostDetailedTraversal,
    isRender: false,
    requestTiles: true,
    ignoreCommands: true,
  });

  passOptions[Cesium3DTilePass.MOST_DETAILED_PICK] = Object.freeze({
    traversal: Cesium3DTilesetMostDetailedTraversal,
    isRender: false,
    requestTiles: false,
    ignoreCommands: false,
  });

  Cesium3DTilePass.getPassOptions = function (pass) {
    return passOptions[pass];
  };
  var Cesium3DTilePass$1 = Object.freeze(Cesium3DTilePass);

  /**
   * Represents empty content for tiles in a
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles} tileset that
   * do not have content, e.g., because they are used to optimize hierarchical culling.
   * <p>
   * Implements the {@link Cesium3DTileContent} interface.
   * </p>
   *
   * @alias Empty3DTileContent
   * @constructor
   *
   * @private
   */
  function Empty3DTileContent(tileset, tile) {
    this._tileset = tileset;
    this._tile = tile;

    this.featurePropertiesDirty = false;
  }

  Object.defineProperties(Empty3DTileContent.prototype, {
    featuresLength: {
      get: function () {
        return 0;
      },
    },

    pointsLength: {
      get: function () {
        return 0;
      },
    },

    trianglesLength: {
      get: function () {
        return 0;
      },
    },

    geometryByteLength: {
      get: function () {
        return 0;
      },
    },

    texturesByteLength: {
      get: function () {
        return 0;
      },
    },

    batchTableByteLength: {
      get: function () {
        return 0;
      },
    },

    innerContents: {
      get: function () {
        return undefined;
      },
    },

    readyPromise: {
      get: function () {
        return undefined;
      },
    },

    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    tile: {
      get: function () {
        return this._tile;
      },
    },

    url: {
      get: function () {
        return undefined;
      },
    },

    batchTable: {
      get: function () {
        return undefined;
      },
    },
  });

  /**
   * Part of the {@link Cesium3DTileContent} interface.  <code>Empty3DTileContent</code>
   * always returns <code>false</code> since a tile of this type does not have any features.
   */
  Empty3DTileContent.prototype.hasProperty = function (batchId, name) {
    return false;
  };

  /**
   * Part of the {@link Cesium3DTileContent} interface.  <code>Empty3DTileContent</code>
   * always returns <code>undefined</code> since a tile of this type does not have any features.
   */
  Empty3DTileContent.prototype.getFeature = function (batchId) {
    return undefined;
  };

  Empty3DTileContent.prototype.applyDebugSettings = function (enabled, color) {};

  Empty3DTileContent.prototype.applyStyle = function (style) {};

  Empty3DTileContent.prototype.update = function (tileset, frameState) {};

  Empty3DTileContent.prototype.isDestroyed = function () {
    return false;
  };

  Empty3DTileContent.prototype.destroy = function () {
    return destroyObject(this);
  };

  /**
   * A tile bounding volume specified as a longitude/latitude/height region.
   * @alias TileBoundingRegion
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Rectangle} options.rectangle The rectangle specifying the longitude and latitude range of the region.
   * @param {Number} [options.minimumHeight=0.0] The minimum height of the region.
   * @param {Number} [options.maximumHeight=0.0] The maximum height of the region.
   * @param {Ellipsoid} [options.ellipsoid=Cesium.Ellipsoid.WGS84] The ellipsoid.
   * @param {Boolean} [options.computeBoundingVolumes=true] True to compute the {@link TileBoundingRegion#boundingVolume} and
   *                  {@link TileBoundingVolume#boundingSphere}. If false, these properties will be undefined.
   *
   * @private
   */
  function TileBoundingRegion(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.rectangle", options.rectangle);
    //>>includeEnd('debug');

    this.rectangle = Rectangle.clone(options.rectangle);
    this.minimumHeight = defaultValue(options.minimumHeight, 0.0);
    this.maximumHeight = defaultValue(options.maximumHeight, 0.0);

    /**
     * The world coordinates of the southwest corner of the tile's rectangle.
     *
     * @type {Cartesian3}
     * @default Cartesian3()
     */
    this.southwestCornerCartesian = new Cartesian3();

    /**
     * The world coordinates of the northeast corner of the tile's rectangle.
     *
     * @type {Cartesian3}
     * @default Cartesian3()
     */
    this.northeastCornerCartesian = new Cartesian3();

    /**
     * A normal that, along with southwestCornerCartesian, defines a plane at the western edge of
     * the tile.  Any position above (in the direction of the normal) this plane is outside the tile.
     *
     * @type {Cartesian3}
     * @default Cartesian3()
     */
    this.westNormal = new Cartesian3();

    /**
     * A normal that, along with southwestCornerCartesian, defines a plane at the southern edge of
     * the tile.  Any position above (in the direction of the normal) this plane is outside the tile.
     * Because points of constant latitude do not necessary lie in a plane, positions below this
     * plane are not necessarily inside the tile, but they are close.
     *
     * @type {Cartesian3}
     * @default Cartesian3()
     */
    this.southNormal = new Cartesian3();

    /**
     * A normal that, along with northeastCornerCartesian, defines a plane at the eastern edge of
     * the tile.  Any position above (in the direction of the normal) this plane is outside the tile.
     *
     * @type {Cartesian3}
     * @default Cartesian3()
     */
    this.eastNormal = new Cartesian3();

    /**
     * A normal that, along with northeastCornerCartesian, defines a plane at the eastern edge of
     * the tile.  Any position above (in the direction of the normal) this plane is outside the tile.
     * Because points of constant latitude do not necessary lie in a plane, positions below this
     * plane are not necessarily inside the tile, but they are close.
     *
     * @type {Cartesian3}
     * @default Cartesian3()
     */
    this.northNormal = new Cartesian3();

    var ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);
    computeBox(this, options.rectangle, ellipsoid);

    if (defaultValue(options.computeBoundingVolumes, true)) {
      // An oriented bounding box that encloses this tile's region.  This is used to calculate tile visibility.
      this._orientedBoundingBox = OrientedBoundingBox.fromRectangle(
        this.rectangle,
        this.minimumHeight,
        this.maximumHeight,
        ellipsoid
      );

      this._boundingSphere = BoundingSphere.fromOrientedBoundingBox(
        this._orientedBoundingBox
      );
    }
  }

  Object.defineProperties(TileBoundingRegion.prototype, {
    /**
     * The underlying bounding volume
     *
     * @memberof TileBoundingRegion.prototype
     *
     * @type {Object}
     * @readonly
     */
    boundingVolume: {
      get: function () {
        return this._orientedBoundingBox;
      },
    },
    /**
     * The underlying bounding sphere
     *
     * @memberof TileBoundingRegion.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     */
    boundingSphere: {
      get: function () {
        return this._boundingSphere;
      },
    },
  });

  var cartesian3Scratch$2 = new Cartesian3();
  var cartesian3Scratch2$1 = new Cartesian3();
  var cartesian3Scratch3$1 = new Cartesian3();
  var eastWestNormalScratch = new Cartesian3();
  var westernMidpointScratch = new Cartesian3();
  var easternMidpointScratch = new Cartesian3();
  var cartographicScratch$2 = new Cartographic();
  var planeScratch = new Plane(Cartesian3.UNIT_X, 0.0);
  var rayScratch = new Ray();

  function computeBox(tileBB, rectangle, ellipsoid) {
    ellipsoid.cartographicToCartesian(
      Rectangle.southwest(rectangle),
      tileBB.southwestCornerCartesian
    );
    ellipsoid.cartographicToCartesian(
      Rectangle.northeast(rectangle),
      tileBB.northeastCornerCartesian
    );

    // The middle latitude on the western edge.
    cartographicScratch$2.longitude = rectangle.west;
    cartographicScratch$2.latitude = (rectangle.south + rectangle.north) * 0.5;
    cartographicScratch$2.height = 0.0;
    var westernMidpointCartesian = ellipsoid.cartographicToCartesian(
      cartographicScratch$2,
      westernMidpointScratch
    );

    // Compute the normal of the plane on the western edge of the tile.
    var westNormal = Cartesian3.cross(
      westernMidpointCartesian,
      Cartesian3.UNIT_Z,
      cartesian3Scratch$2
    );
    Cartesian3.normalize(westNormal, tileBB.westNormal);

    // The middle latitude on the eastern edge.
    cartographicScratch$2.longitude = rectangle.east;
    var easternMidpointCartesian = ellipsoid.cartographicToCartesian(
      cartographicScratch$2,
      easternMidpointScratch
    );

    // Compute the normal of the plane on the eastern edge of the tile.
    var eastNormal = Cartesian3.cross(
      Cartesian3.UNIT_Z,
      easternMidpointCartesian,
      cartesian3Scratch$2
    );
    Cartesian3.normalize(eastNormal, tileBB.eastNormal);

    // Compute the normal of the plane bounding the southern edge of the tile.
    var westVector = Cartesian3.subtract(
      westernMidpointCartesian,
      easternMidpointCartesian,
      cartesian3Scratch$2
    );
    var eastWestNormal = Cartesian3.normalize(westVector, eastWestNormalScratch);

    var south = rectangle.south;
    var southSurfaceNormal;

    if (south > 0.0) {
      // Compute a plane that doesn't cut through the tile.
      cartographicScratch$2.longitude = (rectangle.west + rectangle.east) * 0.5;
      cartographicScratch$2.latitude = south;
      var southCenterCartesian = ellipsoid.cartographicToCartesian(
        cartographicScratch$2,
        rayScratch.origin
      );
      Cartesian3.clone(eastWestNormal, rayScratch.direction);
      var westPlane = Plane.fromPointNormal(
        tileBB.southwestCornerCartesian,
        tileBB.westNormal,
        planeScratch
      );
      // Find a point that is on the west and the south planes
      IntersectionTests.rayPlane(
        rayScratch,
        westPlane,
        tileBB.southwestCornerCartesian
      );
      southSurfaceNormal = ellipsoid.geodeticSurfaceNormal(
        southCenterCartesian,
        cartesian3Scratch2$1
      );
    } else {
      southSurfaceNormal = ellipsoid.geodeticSurfaceNormalCartographic(
        Rectangle.southeast(rectangle),
        cartesian3Scratch2$1
      );
    }
    var southNormal = Cartesian3.cross(
      southSurfaceNormal,
      westVector,
      cartesian3Scratch3$1
    );
    Cartesian3.normalize(southNormal, tileBB.southNormal);

    // Compute the normal of the plane bounding the northern edge of the tile.
    var north = rectangle.north;
    var northSurfaceNormal;
    if (north < 0.0) {
      // Compute a plane that doesn't cut through the tile.
      cartographicScratch$2.longitude = (rectangle.west + rectangle.east) * 0.5;
      cartographicScratch$2.latitude = north;
      var northCenterCartesian = ellipsoid.cartographicToCartesian(
        cartographicScratch$2,
        rayScratch.origin
      );
      Cartesian3.negate(eastWestNormal, rayScratch.direction);
      var eastPlane = Plane.fromPointNormal(
        tileBB.northeastCornerCartesian,
        tileBB.eastNormal,
        planeScratch
      );
      // Find a point that is on the east and the north planes
      IntersectionTests.rayPlane(
        rayScratch,
        eastPlane,
        tileBB.northeastCornerCartesian
      );
      northSurfaceNormal = ellipsoid.geodeticSurfaceNormal(
        northCenterCartesian,
        cartesian3Scratch2$1
      );
    } else {
      northSurfaceNormal = ellipsoid.geodeticSurfaceNormalCartographic(
        Rectangle.northwest(rectangle),
        cartesian3Scratch2$1
      );
    }
    var northNormal = Cartesian3.cross(
      westVector,
      northSurfaceNormal,
      cartesian3Scratch3$1
    );
    Cartesian3.normalize(northNormal, tileBB.northNormal);
  }

  var southwestCornerScratch = new Cartesian3();
  var northeastCornerScratch = new Cartesian3();
  var negativeUnitY = new Cartesian3(0.0, -1.0, 0.0);
  var negativeUnitZ = new Cartesian3(0.0, 0.0, -1.0);
  var vectorScratch = new Cartesian3();

  /**
   * Gets the distance from the camera to the closest point on the tile.  This is used for level of detail selection.
   *
   * @param {FrameState} frameState The state information of the current rendering frame.
   * @returns {Number} The distance from the camera to the closest point on the tile, in meters.
   */
  TileBoundingRegion.prototype.distanceToCamera = function (frameState) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("frameState", frameState);
    //>>includeEnd('debug');
    var camera = frameState.camera;
    var cameraCartesianPosition = camera.positionWC;
    var cameraCartographicPosition = camera.positionCartographic;

    var result = 0.0;
    if (!Rectangle.contains(this.rectangle, cameraCartographicPosition)) {
      var southwestCornerCartesian = this.southwestCornerCartesian;
      var northeastCornerCartesian = this.northeastCornerCartesian;
      var westNormal = this.westNormal;
      var southNormal = this.southNormal;
      var eastNormal = this.eastNormal;
      var northNormal = this.northNormal;

      if (frameState.mode !== SceneMode$1.SCENE3D) {
        southwestCornerCartesian = frameState.mapProjection.project(
          Rectangle.southwest(this.rectangle),
          southwestCornerScratch
        );
        southwestCornerCartesian.z = southwestCornerCartesian.y;
        southwestCornerCartesian.y = southwestCornerCartesian.x;
        southwestCornerCartesian.x = 0.0;
        northeastCornerCartesian = frameState.mapProjection.project(
          Rectangle.northeast(this.rectangle),
          northeastCornerScratch
        );
        northeastCornerCartesian.z = northeastCornerCartesian.y;
        northeastCornerCartesian.y = northeastCornerCartesian.x;
        northeastCornerCartesian.x = 0.0;
        westNormal = negativeUnitY;
        eastNormal = Cartesian3.UNIT_Y;
        southNormal = negativeUnitZ;
        northNormal = Cartesian3.UNIT_Z;
      }

      var vectorFromSouthwestCorner = Cartesian3.subtract(
        cameraCartesianPosition,
        southwestCornerCartesian,
        vectorScratch
      );
      var distanceToWestPlane = Cartesian3.dot(
        vectorFromSouthwestCorner,
        westNormal
      );
      var distanceToSouthPlane = Cartesian3.dot(
        vectorFromSouthwestCorner,
        southNormal
      );

      var vectorFromNortheastCorner = Cartesian3.subtract(
        cameraCartesianPosition,
        northeastCornerCartesian,
        vectorScratch
      );
      var distanceToEastPlane = Cartesian3.dot(
        vectorFromNortheastCorner,
        eastNormal
      );
      var distanceToNorthPlane = Cartesian3.dot(
        vectorFromNortheastCorner,
        northNormal
      );

      if (distanceToWestPlane > 0.0) {
        result += distanceToWestPlane * distanceToWestPlane;
      } else if (distanceToEastPlane > 0.0) {
        result += distanceToEastPlane * distanceToEastPlane;
      }

      if (distanceToSouthPlane > 0.0) {
        result += distanceToSouthPlane * distanceToSouthPlane;
      } else if (distanceToNorthPlane > 0.0) {
        result += distanceToNorthPlane * distanceToNorthPlane;
      }
    }

    var cameraHeight;
    var minimumHeight;
    var maximumHeight;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      cameraHeight = cameraCartographicPosition.height;
      minimumHeight = this.minimumHeight;
      maximumHeight = this.maximumHeight;
    } else {
      cameraHeight = cameraCartesianPosition.x;
      minimumHeight = 0.0;
      maximumHeight = 0.0;
    }

    if (cameraHeight > maximumHeight) {
      var distanceAboveTop = cameraHeight - maximumHeight;
      result += distanceAboveTop * distanceAboveTop;
    } else if (cameraHeight < minimumHeight) {
      var distanceBelowBottom = minimumHeight - cameraHeight;
      result += distanceBelowBottom * distanceBelowBottom;
    }

    return Math.sqrt(result);
  };

  /**
   * Determines which side of a plane this box is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
   *                      intersects the plane.
   */
  TileBoundingRegion.prototype.intersectPlane = function (plane) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("plane", plane);
    //>>includeEnd('debug');
    return this._orientedBoundingBox.intersectPlane(plane);
  };

  /**
   * Creates a debug primitive that shows the outline of the tile bounding region.
   *
   * @param {Color} color The desired color of the primitive's mesh
   * @return {Primitive}
   *
   * @private
   */
  TileBoundingRegion.prototype.createDebugVolume = function (color) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("color", color);
    //>>includeEnd('debug');

    var modelMatrix = new Matrix4.clone(Matrix4.IDENTITY);
    var geometry = new RectangleOutlineGeometry({
      rectangle: this.rectangle,
      height: this.minimumHeight,
      extrudedHeight: this.maximumHeight,
    });
    var instance = new GeometryInstance({
      geometry: geometry,
      id: "outline",
      modelMatrix: modelMatrix,
      attributes: {
        color: ColorGeometryInstanceAttribute.fromColor(color),
      },
    });

    return new Primitive({
      geometryInstances: instance,
      appearance: new PerInstanceColorAppearance({
        translucent: false,
        flat: true,
      }),
      asynchronous: false,
    });
  };

  /**
   * A tile bounding volume specified as a sphere.
   * @alias TileBoundingSphere
   * @constructor
   *
   * @param {Cartesian3} [center=Cartesian3.ZERO] The center of the bounding sphere.
   * @param {Number} [radius=0.0] The radius of the bounding sphere.
   *
   * @private
   */
  function TileBoundingSphere(center, radius) {
    if (radius === 0) {
      radius = CesiumMath.EPSILON7;
    }
    this._boundingSphere = new BoundingSphere(center, radius);
  }

  Object.defineProperties(TileBoundingSphere.prototype, {
    /**
     * The center of the bounding sphere
     *
     * @memberof TileBoundingSphere.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    center: {
      get: function () {
        return this._boundingSphere.center;
      },
    },

    /**
     * The radius of the bounding sphere
     *
     * @memberof TileBoundingSphere.prototype
     *
     * @type {Number}
     * @readonly
     */
    radius: {
      get: function () {
        return this._boundingSphere.radius;
      },
    },

    /**
     * The underlying bounding volume
     *
     * @memberof TileBoundingSphere.prototype
     *
     * @type {Object}
     * @readonly
     */
    boundingVolume: {
      get: function () {
        return this._boundingSphere;
      },
    },
    /**
     * The underlying bounding sphere
     *
     * @memberof TileBoundingSphere.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     */
    boundingSphere: {
      get: function () {
        return this._boundingSphere;
      },
    },
  });

  /**
   * Computes the distance between this bounding sphere and the camera attached to frameState.
   *
   * @param {FrameState} frameState The frameState to which the camera is attached.
   * @returns {Number} The distance between the camera and the bounding sphere in meters. Returns 0 if the camera is inside the bounding volume.
   *
   */
  TileBoundingSphere.prototype.distanceToCamera = function (frameState) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("frameState", frameState);
    //>>includeEnd('debug');
    var boundingSphere = this._boundingSphere;
    return Math.max(
      0.0,
      Cartesian3.distance(boundingSphere.center, frameState.camera.positionWC) -
        boundingSphere.radius
    );
  };

  /**
   * Determines which side of a plane this sphere is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire sphere is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire sphere is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the sphere
   *                      intersects the plane.
   */
  TileBoundingSphere.prototype.intersectPlane = function (plane) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("plane", plane);
    //>>includeEnd('debug');
    return BoundingSphere.intersectPlane(this._boundingSphere, plane);
  };

  /**
   * Update the bounding sphere after the tile is transformed.
   *
   * @param {Cartesian3} center The center of the bounding sphere.
   * @param {Number} radius The radius of the bounding sphere.
   */
  TileBoundingSphere.prototype.update = function (center, radius) {
    Cartesian3.clone(center, this._boundingSphere.center);
    this._boundingSphere.radius = radius;
  };

  /**
   * Creates a debug primitive that shows the outline of the sphere.
   *
   * @param {Color} color The desired color of the primitive's mesh
   * @return {Primitive}
   */
  TileBoundingSphere.prototype.createDebugVolume = function (color) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("color", color);
    //>>includeEnd('debug');
    var geometry = new SphereOutlineGeometry({
      radius: this.radius,
    });
    var modelMatrix = Matrix4.fromTranslation(
      this.center,
      new Matrix4.clone(Matrix4.IDENTITY)
    );
    var instance = new GeometryInstance({
      geometry: geometry,
      id: "outline",
      modelMatrix: modelMatrix,
      attributes: {
        color: ColorGeometryInstanceAttribute.fromColor(color),
      },
    });

    return new Primitive({
      geometryInstances: instance,
      appearance: new PerInstanceColorAppearance({
        translucent: false,
        flat: true,
      }),
      asynchronous: false,
    });
  };

  var scratchU = new Cartesian3();
  var scratchV = new Cartesian3();
  var scratchW$1 = new Cartesian3();
  var scratchCartesian$3 = new Cartesian3();

  function computeMissingVector(a, b, result) {
    result = Cartesian3.cross(a, b, result);
    var magnitude = Cartesian3.magnitude(result);
    return Cartesian3.multiplyByScalar(
      result,
      CesiumMath.EPSILON7 / magnitude,
      result
    );
  }

  function findOrthogonalVector(a, result) {
    var temp = Cartesian3.normalize(a, scratchCartesian$3);
    var b = Cartesian3.equalsEpsilon(temp, Cartesian3.UNIT_X, CesiumMath.EPSILON6)
      ? Cartesian3.UNIT_Y
      : Cartesian3.UNIT_X;
    return computeMissingVector(a, b, result);
  }

  function checkHalfAxes(halfAxes) {
    var u = Matrix3.getColumn(halfAxes, 0, scratchU);
    var v = Matrix3.getColumn(halfAxes, 1, scratchV);
    var w = Matrix3.getColumn(halfAxes, 2, scratchW$1);

    var uZero = Cartesian3.equals(u, Cartesian3.ZERO);
    var vZero = Cartesian3.equals(v, Cartesian3.ZERO);
    var wZero = Cartesian3.equals(w, Cartesian3.ZERO);

    if (!uZero && !vZero && !wZero) {
      return halfAxes;
    }
    if (uZero && vZero && wZero) {
      halfAxes[0] = CesiumMath.EPSILON7;
      halfAxes[4] = CesiumMath.EPSILON7;
      halfAxes[8] = CesiumMath.EPSILON7;
      return halfAxes;
    }
    if (uZero && !vZero && !wZero) {
      u = computeMissingVector(v, w, u);
    } else if (!uZero && vZero && !wZero) {
      v = computeMissingVector(u, w, v);
    } else if (!uZero && !vZero && wZero) {
      w = computeMissingVector(v, u, w);
    } else if (!uZero) {
      v = findOrthogonalVector(u, v);
      w = computeMissingVector(v, u, w);
    } else if (!vZero) {
      u = findOrthogonalVector(v, u);
      w = computeMissingVector(v, u, w);
    } else if (!wZero) {
      u = findOrthogonalVector(w, u);
      v = computeMissingVector(w, u, v);
    }

    Matrix3.setColumn(halfAxes, 0, u, halfAxes);
    Matrix3.setColumn(halfAxes, 1, v, halfAxes);
    Matrix3.setColumn(halfAxes, 2, w, halfAxes);

    return halfAxes;
  }

  /**
   * A tile bounding volume specified as an oriented bounding box.
   * @alias TileOrientedBoundingBox
   * @constructor
   *
   * @param {Cartesian3} [center=Cartesian3.ZERO] The center of the box.
   * @param {Matrix3} [halfAxes=Matrix3.ZERO] The three orthogonal half-axes of the bounding box.
   *                                          Equivalently, the transformation matrix, to rotate and scale a 2x2x2
   *                                          cube centered at the origin.
   *
   * @private
   */
  function TileOrientedBoundingBox(center, halfAxes) {
    halfAxes = checkHalfAxes(halfAxes);
    this._orientedBoundingBox = new OrientedBoundingBox(center, halfAxes);
    this._boundingSphere = BoundingSphere.fromOrientedBoundingBox(
      this._orientedBoundingBox
    );
  }

  Object.defineProperties(TileOrientedBoundingBox.prototype, {
    /**
     * The underlying bounding volume.
     *
     * @memberof TileOrientedBoundingBox.prototype
     *
     * @type {Object}
     * @readonly
     */
    boundingVolume: {
      get: function () {
        return this._orientedBoundingBox;
      },
    },
    /**
     * The underlying bounding sphere.
     *
     * @memberof TileOrientedBoundingBox.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     */
    boundingSphere: {
      get: function () {
        return this._boundingSphere;
      },
    },
  });

  /**
   * Computes the distance between this bounding box and the camera attached to frameState.
   *
   * @param {FrameState} frameState The frameState to which the camera is attached.
   * @returns {Number} The distance between the camera and the bounding box in meters. Returns 0 if the camera is inside the bounding volume.
   */
  TileOrientedBoundingBox.prototype.distanceToCamera = function (frameState) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("frameState", frameState);
    //>>includeEnd('debug');
    return Math.sqrt(
      this._orientedBoundingBox.distanceSquaredTo(frameState.camera.positionWC)
    );
  };

  /**
   * Determines which side of a plane this box is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
   *                      intersects the plane.
   */
  TileOrientedBoundingBox.prototype.intersectPlane = function (plane) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("plane", plane);
    //>>includeEnd('debug');
    return this._orientedBoundingBox.intersectPlane(plane);
  };

  /**
   * Update the bounding box after the tile is transformed.
   *
   * @param {Cartesian3} center The center of the box.
   * @param {Matrix3} halfAxes The three orthogonal half-axes of the bounding box.
   *                           Equivalently, the transformation matrix, to rotate and scale a 2x2x2
   *                           cube centered at the origin.
   */
  TileOrientedBoundingBox.prototype.update = function (center, halfAxes) {
    Cartesian3.clone(center, this._orientedBoundingBox.center);
    halfAxes = checkHalfAxes(halfAxes);
    Matrix3.clone(halfAxes, this._orientedBoundingBox.halfAxes);
    BoundingSphere.fromOrientedBoundingBox(
      this._orientedBoundingBox,
      this._boundingSphere
    );
  };

  /**
   * Creates a debug primitive that shows the outline of the box.
   *
   * @param {Color} color The desired color of the primitive's mesh
   * @return {Primitive}
   */
  TileOrientedBoundingBox.prototype.createDebugVolume = function (color) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("color", color);
    //>>includeEnd('debug');

    var geometry = new BoxOutlineGeometry({
      // Make a 2x2x2 cube
      minimum: new Cartesian3(-1.0, -1.0, -1.0),
      maximum: new Cartesian3(1.0, 1.0, 1.0),
    });
    var modelMatrix = Matrix4.fromRotationTranslation(
      this.boundingVolume.halfAxes,
      this.boundingVolume.center
    );
    var instance = new GeometryInstance({
      geometry: geometry,
      id: "outline",
      modelMatrix: modelMatrix,
      attributes: {
        color: ColorGeometryInstanceAttribute.fromColor(color),
      },
    });

    return new Primitive({
      geometryInstances: instance,
      appearance: new PerInstanceColorAppearance({
        translucent: false,
        flat: true,
      }),
      asynchronous: false,
    });
  };

  /**
   * A tile in a {@link Cesium3DTileset}.  When a tile is first created, its content is not loaded;
   * the content is loaded on-demand when needed based on the view.
   * <p>
   * Do not construct this directly, instead access tiles through {@link Cesium3DTileset#tileVisible}.
   * </p>
   *
   * @alias Cesium3DTile
   * @constructor
   */
  function Cesium3DTile(tileset, baseResource, header, parent) {
    this._tileset = tileset;
    this._header = header;
    var contentHeader = header.content;

    /**
     * The local transform of this tile.
     * @type {Matrix4}
     */
    this.transform = defined(header.transform)
      ? Matrix4.unpack(header.transform)
      : Matrix4.clone(Matrix4.IDENTITY);

    var parentTransform = defined(parent)
      ? parent.computedTransform
      : tileset.modelMatrix;
    var computedTransform = Matrix4.multiply(
      parentTransform,
      this.transform,
      new Matrix4()
    );

    var parentInitialTransform = defined(parent)
      ? parent._initialTransform
      : Matrix4.IDENTITY;
    this._initialTransform = Matrix4.multiply(
      parentInitialTransform,
      this.transform,
      new Matrix4()
    );

    /**
     * The final computed transform of this tile.
     * @type {Matrix4}
     * @readonly
     */
    this.computedTransform = computedTransform;

    this._boundingVolume = this.createBoundingVolume(
      header.boundingVolume,
      computedTransform
    );
    this._boundingVolume2D = undefined;

    var contentBoundingVolume;

    if (defined(contentHeader) && defined(contentHeader.boundingVolume)) {
      // Non-leaf tiles may have a content bounding-volume, which is a tight-fit bounding volume
      // around only the features in the tile.  This box is useful for culling for rendering,
      // but not for culling for traversing the tree since it does not guarantee spatial coherence, i.e.,
      // since it only bounds features in the tile, not the entire tile, children may be
      // outside of this box.
      contentBoundingVolume = this.createBoundingVolume(
        contentHeader.boundingVolume,
        computedTransform
      );
    }
    this._contentBoundingVolume = contentBoundingVolume;
    this._contentBoundingVolume2D = undefined;

    var viewerRequestVolume;
    if (defined(header.viewerRequestVolume)) {
      viewerRequestVolume = this.createBoundingVolume(
        header.viewerRequestVolume,
        computedTransform
      );
    }
    this._viewerRequestVolume = viewerRequestVolume;

    /**
     * The error, in meters, introduced if this tile is rendered and its children are not.
     * This is used to compute screen space error, i.e., the error measured in pixels.
     *
     * @type {Number}
     * @readonly
     */
    this.geometricError = header.geometricError;
    this._geometricError = header.geometricError;

    if (!defined(this._geometricError)) {
      this._geometricError = defined(parent)
        ? parent.geometricError
        : tileset._geometricError;
      Cesium3DTile._deprecationWarning(
        "geometricErrorUndefined",
        "Required property geometricError is undefined for this tile. Using parent's geometric error instead."
      );
    }

    this.updateGeometricErrorScale();

    var refine;
    if (defined(header.refine)) {
      if (header.refine === "replace" || header.refine === "add") {
        Cesium3DTile._deprecationWarning(
          "lowercase-refine",
          'This tile uses a lowercase refine "' +
            header.refine +
            '". Instead use "' +
            header.refine.toUpperCase() +
            '".'
        );
      }
      refine =
        header.refine.toUpperCase() === "REPLACE"
          ? Cesium3DTileRefine$1.REPLACE
          : Cesium3DTileRefine$1.ADD;
    } else if (defined(parent)) {
      // Inherit from parent tile if omitted.
      refine = parent.refine;
    } else {
      refine = Cesium3DTileRefine$1.REPLACE;
    }

    /**
     * Specifies the type of refinement that is used when traversing this tile for rendering.
     *
     * @type {Cesium3DTileRefine}
     * @readonly
     * @private
     */
    this.refine = refine;

    /**
     * Gets the tile's children.
     *
     * @type {Cesium3DTile[]}
     * @readonly
     */
    this.children = [];

    /**
     * This tile's parent or <code>undefined</code> if this tile is the root.
     * <p>
     * When a tile's content points to an external tileset JSON file, the external tileset's
     * root tile's parent is not <code>undefined</code>; instead, the parent references
     * the tile (with its content pointing to an external tileset JSON file) as if the two tilesets were merged.
     * </p>
     *
     * @type {Cesium3DTile}
     * @readonly
     */
    this.parent = parent;

    var content;
    var hasEmptyContent;
    var contentState;
    var contentResource;
    var serverKey;

    baseResource = Resource.createIfNeeded(baseResource);

    if (defined(contentHeader)) {
      var contentHeaderUri = contentHeader.uri;
      if (defined(contentHeader.url)) {
        Cesium3DTile._deprecationWarning(
          "contentUrl",
          'This tileset JSON uses the "content.url" property which has been deprecated. Use "content.uri" instead.'
        );
        contentHeaderUri = contentHeader.url;
      }
      hasEmptyContent = false;
      contentState = Cesium3DTileContentState$1.UNLOADED;
      contentResource = baseResource.getDerivedResource({
        url: contentHeaderUri,
      });
      serverKey = RequestScheduler.getServerKey(
        contentResource.getUrlComponent()
      );
    } else {
      content = new Empty3DTileContent(tileset, this);
      hasEmptyContent = true;
      contentState = Cesium3DTileContentState$1.READY;
    }

    this._content = content;
    this._contentResource = contentResource;
    this._contentState = contentState;
    this._contentReadyToProcessPromise = undefined;
    this._contentReadyPromise = undefined;
    this._expiredContent = undefined;

    this._serverKey = serverKey;

    /**
     * When <code>true</code>, the tile has no content.
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    this.hasEmptyContent = hasEmptyContent;

    /**
     * When <code>true</code>, the tile's content points to an external tileset.
     * <p>
     * This is <code>false</code> until the tile's content is loaded.
     * </p>
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    this.hasTilesetContent = false;

    /**
     * The node in the tileset's LRU cache, used to determine when to unload a tile's content.
     *
     * See {@link Cesium3DTilesetCache}
     *
     * @type {DoublyLinkedListNode}
     * @readonly
     *
     * @private
     */
    this.cacheNode = undefined;

    var expire = header.expire;
    var expireDuration;
    var expireDate;
    if (defined(expire)) {
      expireDuration = expire.duration;
      if (defined(expire.date)) {
        expireDate = JulianDate.fromIso8601(expire.date);
      }
    }

    /**
     * The time in seconds after the tile's content is ready when the content expires and new content is requested.
     *
     * @type {Number}
     */
    this.expireDuration = expireDuration;

    /**
     * The date when the content expires and new content is requested.
     *
     * @type {JulianDate}
     */
    this.expireDate = expireDate;

    /**
     * The time when a style was last applied to this tile.
     *
     * @type {Number}
     *
     * @private
     */
    this.lastStyleTime = 0.0;

    /**
     * Marks whether the tile's children bounds are fully contained within the tile's bounds
     *
     * @type {Cesium3DTileOptimizationHint}
     *
     * @private
     */
    this._optimChildrenWithinParent = Cesium3DTileOptimizationHint$1.NOT_COMPUTED;

    /**
     * Tracks if the tile's relationship with a ClippingPlaneCollection has changed with regards
     * to the ClippingPlaneCollection's state.
     *
     * @type {Boolean}
     *
     * @private
     */
    this.clippingPlanesDirty = false;

    /**
     * Tracks if the tile's request should be deferred until all non-deferred
     * tiles load.
     *
     * @type {Boolean}
     *
     * @private
     */
    this.priorityDeferred = false;

    // Members that are updated every frame for tree traversal and rendering optimizations:
    this._distanceToCamera = 0.0;
    this._centerZDepth = 0.0;
    this._screenSpaceError = 0.0;
    this._screenSpaceErrorProgressiveResolution = 0.0; // The screen space error at a given screen height of tileset.progressiveResolutionHeightFraction * screenHeight
    this._visibilityPlaneMask = 0;
    this._visible = false;
    this._inRequestVolume = false;

    this._finalResolution = true;
    this._depth = 0;
    this._stackLength = 0;
    this._selectionDepth = 0;

    this._updatedVisibilityFrame = 0;
    this._touchedFrame = 0;
    this._visitedFrame = 0;
    this._selectedFrame = 0;
    this._requestedFrame = 0;
    this._ancestorWithContent = undefined;
    this._ancestorWithContentAvailable = undefined;
    this._refines = false;
    this._shouldSelect = false;
    this._isClipped = true;
    this._clippingPlanesState = 0; // encapsulates (_isClipped, clippingPlanes.enabled) and number/function
    this._debugBoundingVolume = undefined;
    this._debugContentBoundingVolume = undefined;
    this._debugViewerRequestVolume = undefined;
    this._debugColor = Color.fromRandom({ alpha: 1.0 });
    this._debugColorizeTiles = false;

    this._priority = 0.0; // The priority used for request sorting
    this._priorityHolder = this; // Reference to the ancestor up the tree that holds the _foveatedFactor and _distanceToCamera for all tiles in the refinement chain.
    this._priorityProgressiveResolution = false;
    this._priorityProgressiveResolutionScreenSpaceErrorLeaf = false;
    this._priorityReverseScreenSpaceError = 0.0;
    this._foveatedFactor = 0.0;
    this._wasMinPriorityChild = false; // Needed for knowing when to continue a refinement chain. Gets reset in updateTile in traversal and gets set in updateAndPushChildren in traversal.

    this._loadTimestamp = new JulianDate();

    this._commandsLength = 0;

    this._color = undefined;
    this._colorDirty = false;

    this._request = undefined;
  }

  // This can be overridden for testing purposes
  Cesium3DTile._deprecationWarning = deprecationWarning;

  Object.defineProperties(Cesium3DTile.prototype, {
    /**
     * The tileset containing this tile.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Cesium3DTileset}
     * @readonly
     */
    tileset: {
      get: function () {
        return this._tileset;
      },
    },

    /**
     * The tile's content.  This represents the actual tile's payload,
     * not the content's metadata in the tileset JSON file.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Cesium3DTileContent}
     * @readonly
     */
    content: {
      get: function () {
        return this._content;
      },
    },

    /**
     * Get the tile's bounding volume.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {TileBoundingVolume}
     * @readonly
     * @private
     */
    boundingVolume: {
      get: function () {
        return this._boundingVolume;
      },
    },

    /**
     * Get the bounding volume of the tile's contents.  This defaults to the
     * tile's bounding volume when the content's bounding volume is
     * <code>undefined</code>.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {TileBoundingVolume}
     * @readonly
     * @private
     */
    contentBoundingVolume: {
      get: function () {
        return defaultValue(this._contentBoundingVolume, this._boundingVolume);
      },
    },

    /**
     * Get the bounding sphere derived from the tile's bounding volume.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     */
    boundingSphere: {
      get: function () {
        return this._boundingVolume.boundingSphere;
      },
    },

    /**
     * Returns the <code>extras</code> property in the tileset JSON for this tile, which contains application specific metadata.
     * Returns <code>undefined</code> if <code>extras</code> does not exist.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {*}
     * @readonly
     * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification#specifying-extensions-and-application-specific-extras|Extras in the 3D Tiles specification.}
     */
    extras: {
      get: function () {
        return this._header.extras;
      },
    },

    /**
     * Gets or sets the tile's highlight color.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Color}
     *
     * @default {@link Color.WHITE}
     *
     * @private
     */
    color: {
      get: function () {
        if (!defined(this._color)) {
          this._color = new Color();
        }
        return Color.clone(this._color);
      },
      set: function (value) {
        this._color = Color.clone(value, this._color);
        this._colorDirty = true;
      },
    },

    /**
     * Determines if the tile has available content to render.  <code>true</code> if the tile's
     * content is ready or if it has expired content that renders while new content loads; otherwise,
     * <code>false</code>.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    contentAvailable: {
      get: function () {
        return (
          (this.contentReady &&
            !this.hasEmptyContent &&
            !this.hasTilesetContent) ||
          (defined(this._expiredContent) && !this.contentFailed)
        );
      },
    },

    /**
     * Determines if the tile's content is ready. This is automatically <code>true</code> for
     * tile's with empty content.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    contentReady: {
      get: function () {
        return this._contentState === Cesium3DTileContentState$1.READY;
      },
    },

    /**
     * Determines if the tile's content has not be requested. <code>true</code> if tile's
     * content has not be requested; otherwise, <code>false</code>.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    contentUnloaded: {
      get: function () {
        return this._contentState === Cesium3DTileContentState$1.UNLOADED;
      },
    },

    /**
     * Determines if the tile's content is expired. <code>true</code> if tile's
     * content is expired; otherwise, <code>false</code>.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    contentExpired: {
      get: function () {
        return this._contentState === Cesium3DTileContentState$1.EXPIRED;
      },
    },

    /**
     * Determines if the tile's content failed to load.  <code>true</code> if the tile's
     * content failed to load; otherwise, <code>false</code>.
     *
     * @memberof Cesium3DTile.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @private
     */
    contentFailed: {
      get: function () {
        return this._contentState === Cesium3DTileContentState$1.FAILED;
      },
    },

    /**
     * Gets the promise that will be resolved when the tile's content is ready to process.
     * This happens after the content is downloaded but before the content is ready
     * to render.
     * <p>
     * The promise remains <code>undefined</code> until the tile's content is requested.
     * </p>
     *
     * @type {Promise.<Cesium3DTileContent>}
     * @readonly
     *
     * @private
     */
    contentReadyToProcessPromise: {
      get: function () {
        if (defined(this._contentReadyToProcessPromise)) {
          return this._contentReadyToProcessPromise.promise;
        }
        return undefined;
      },
    },

    /**
     * Gets the promise that will be resolved when the tile's content is ready to render.
     * <p>
     * The promise remains <code>undefined</code> until the tile's content is requested.
     * </p>
     *
     * @type {Promise.<Cesium3DTileContent>}
     * @readonly
     *
     * @private
     */
    contentReadyPromise: {
      get: function () {
        if (defined(this._contentReadyPromise)) {
          return this._contentReadyPromise.promise;
        }
        return undefined;
      },
    },

    /**
     * Returns the number of draw commands used by this tile.
     *
     * @readonly
     *
     * @private
     */
    commandsLength: {
      get: function () {
        return this._commandsLength;
      },
    },
  });

  var scratchCartesian$4 = new Cartesian3();
  function isPriorityDeferred(tile, frameState) {
    var tileset = tile._tileset;

    // If closest point on line is inside the sphere then set foveatedFactor to 0. Otherwise, the dot product is with the line from camera to the point on the sphere that is closest to the line.
    var camera = frameState.camera;
    var boundingSphere = tile.boundingSphere;
    var radius = boundingSphere.radius;
    var scaledCameraDirection = Cartesian3.multiplyByScalar(
      camera.directionWC,
      tile._centerZDepth,
      scratchCartesian$4
    );
    var closestPointOnLine = Cartesian3.add(
      camera.positionWC,
      scaledCameraDirection,
      scratchCartesian$4
    );
    // The distance from the camera's view direction to the tile.
    var toLine = Cartesian3.subtract(
      closestPointOnLine,
      boundingSphere.center,
      scratchCartesian$4
    );
    var distanceToCenterLine = Cartesian3.magnitude(toLine);
    var notTouchingSphere = distanceToCenterLine > radius;

    // If camera's direction vector is inside the bounding sphere then consider
    // this tile right along the line of sight and set _foveatedFactor to 0.
    // Otherwise,_foveatedFactor is one minus the dot product of the camera's direction
    // and the vector between the camera and the point on the bounding sphere closest to the view line.
    if (notTouchingSphere) {
      var toLineNormalized = Cartesian3.normalize(toLine, scratchCartesian$4);
      var scaledToLine = Cartesian3.multiplyByScalar(
        toLineNormalized,
        radius,
        scratchCartesian$4
      );
      var closestOnSphere = Cartesian3.add(
        boundingSphere.center,
        scaledToLine,
        scratchCartesian$4
      );
      var toClosestOnSphere = Cartesian3.subtract(
        closestOnSphere,
        camera.positionWC,
        scratchCartesian$4
      );
      var toClosestOnSphereNormalize = Cartesian3.normalize(
        toClosestOnSphere,
        scratchCartesian$4
      );
      tile._foveatedFactor =
        1.0 -
        Math.abs(Cartesian3.dot(camera.directionWC, toClosestOnSphereNormalize));
    } else {
      tile._foveatedFactor = 0.0;
    }

    // Skip this feature if: non-skipLevelOfDetail and replace refine, if the foveated settings are turned off, if tile is progressive resolution and replace refine and skipLevelOfDetail (will help get rid of ancestor artifacts faster)
    // Or if the tile is a preload of any kind
    var replace = tile.refine === Cesium3DTileRefine$1.REPLACE;
    var skipLevelOfDetail = tileset._skipLevelOfDetail;
    if (
      (replace && !skipLevelOfDetail) ||
      !tileset.foveatedScreenSpaceError ||
      tileset.foveatedConeSize === 1.0 ||
      (tile._priorityProgressiveResolution && replace && skipLevelOfDetail) ||
      tileset._pass === Cesium3DTilePass$1.PRELOAD_FLIGHT ||
      tileset._pass === Cesium3DTilePass$1.PRELOAD
    ) {
      return false;
    }

    var maximumFovatedFactor = 1.0 - Math.cos(camera.frustum.fov * 0.5); // 0.14 for fov = 60. NOTE very hard to defer vertically foveated tiles since max is based on fovy (which is fov). Lowering the 0.5 to a smaller fraction of the screen height will start to defer vertically foveated tiles.
    var foveatedConeFactor = tileset.foveatedConeSize * maximumFovatedFactor;

    // If it's inside the user-defined view cone, then it should not be deferred.
    if (tile._foveatedFactor <= foveatedConeFactor) {
      return false;
    }

    // Relax SSE based on how big the angle is between the tile and the edge of the foveated cone.
    var range = maximumFovatedFactor - foveatedConeFactor;
    var normalizedFoveatedFactor = CesiumMath.clamp(
      (tile._foveatedFactor - foveatedConeFactor) / range,
      0.0,
      1.0
    );
    var sseRelaxation = tileset.foveatedInterpolationCallback(
      tileset.foveatedMinimumScreenSpaceErrorRelaxation,
      tileset.maximumScreenSpaceError,
      normalizedFoveatedFactor
    );
    var sse =
      tile._screenSpaceError === 0.0 && defined(tile.parent)
        ? tile.parent._screenSpaceError * 0.5
        : tile._screenSpaceError;

    return tileset.maximumScreenSpaceError - sseRelaxation <= sse;
  }

  var scratchJulianDate$1 = new JulianDate();

  /**
   * Get the tile's screen space error.
   *
   * @private
   */
  Cesium3DTile.prototype.getScreenSpaceError = function (
    frameState,
    useParentGeometricError,
    progressiveResolutionHeightFraction
  ) {
    var tileset = this._tileset;
    var heightFraction = defaultValue(progressiveResolutionHeightFraction, 1.0);
    var parentGeometricError = defined(this.parent)
      ? this.parent.geometricError
      : tileset._geometricError;
    var geometricError = useParentGeometricError
      ? parentGeometricError
      : this.geometricError;
    if (geometricError === 0.0) {
      // Leaf tiles do not have any error so save the computation
      return 0.0;
    }
    var camera = frameState.camera;
    var frustum = camera.frustum;
    var context = frameState.context;
    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight * heightFraction;
    var error;
    if (
      frameState.mode === SceneMode$1.SCENE2D ||
      frustum instanceof OrthographicFrustum
    ) {
      if (defined(frustum._offCenterFrustum)) {
        frustum = frustum._offCenterFrustum;
      }
      var pixelSize =
        Math.max(frustum.top - frustum.bottom, frustum.right - frustum.left) /
        Math.max(width, height);
      error = geometricError / pixelSize;
    } else {
      // Avoid divide by zero when viewer is inside the tile
      var distance = Math.max(this._distanceToCamera, CesiumMath.EPSILON7);
      var sseDenominator = camera.frustum.sseDenominator;
      error = (geometricError * height) / (distance * sseDenominator);
      if (tileset.dynamicScreenSpaceError) {
        var density = tileset._dynamicScreenSpaceErrorComputedDensity;
        var factor = tileset.dynamicScreenSpaceErrorFactor;
        var dynamicError = CesiumMath.fog(distance, density) * factor;
        error -= dynamicError;
      }
    }

    error /= frameState.pixelRatio;

    return error;
  };

  function isPriorityProgressiveResolution(tileset, tile) {
    if (
      tileset.progressiveResolutionHeightFraction <= 0.0 ||
      tileset.progressiveResolutionHeightFraction > 0.5
    ) {
      return false;
    }

    var isProgressiveResolutionTile =
      tile._screenSpaceErrorProgressiveResolution >
      tileset._maximumScreenSpaceError; // Mark non-SSE leaves
    tile._priorityProgressiveResolutionScreenSpaceErrorLeaf = false; // Needed for skipLOD
    var parent = tile.parent;
    var maximumScreenSpaceError = tileset._maximumScreenSpaceError;
    var tilePasses =
      tile._screenSpaceErrorProgressiveResolution <= maximumScreenSpaceError;
    var parentFails =
      defined(parent) &&
      parent._screenSpaceErrorProgressiveResolution > maximumScreenSpaceError;
    if (tilePasses && parentFails) {
      // A progressive resolution SSE leaf, promote its priority as well
      tile._priorityProgressiveResolutionScreenSpaceErrorLeaf = true;
      isProgressiveResolutionTile = true;
    }
    return isProgressiveResolutionTile;
  }

  function getPriorityReverseScreenSpaceError(tileset, tile) {
    var parent = tile.parent;
    var useParentScreenSpaceError =
      defined(parent) &&
      (!tileset._skipLevelOfDetail ||
        tile._screenSpaceError === 0.0 ||
        parent.hasTilesetContent);
    var screenSpaceError = useParentScreenSpaceError
      ? parent._screenSpaceError
      : tile._screenSpaceError;
    return tileset.root._screenSpaceError - screenSpaceError;
  }

  /**
   * Update the tile's visibility.
   *
   * @private
   */
  Cesium3DTile.prototype.updateVisibility = function (frameState) {
    var parent = this.parent;
    var tileset = this._tileset;
    var parentTransform = defined(parent)
      ? parent.computedTransform
      : tileset.modelMatrix;
    var parentVisibilityPlaneMask = defined(parent)
      ? parent._visibilityPlaneMask
      : CullingVolume.MASK_INDETERMINATE;
    this.updateTransform(parentTransform);
    this._distanceToCamera = this.distanceToTile(frameState);
    this._centerZDepth = this.distanceToTileCenter(frameState);
    this._screenSpaceError = this.getScreenSpaceError(frameState, false);
    this._screenSpaceErrorProgressiveResolution = this.getScreenSpaceError(
      frameState,
      false,
      tileset.progressiveResolutionHeightFraction
    );
    this._visibilityPlaneMask = this.visibility(
      frameState,
      parentVisibilityPlaneMask
    ); // Use parent's plane mask to speed up visibility test
    this._visible = this._visibilityPlaneMask !== CullingVolume.MASK_OUTSIDE;
    this._inRequestVolume = this.insideViewerRequestVolume(frameState);
    this._priorityReverseScreenSpaceError = getPriorityReverseScreenSpaceError(
      tileset,
      this
    );
    this._priorityProgressiveResolution = isPriorityProgressiveResolution(
      tileset,
      this
    );
    this.priorityDeferred = isPriorityDeferred(this, frameState);
  };

  /**
   * Update whether the tile has expired.
   *
   * @private
   */
  Cesium3DTile.prototype.updateExpiration = function () {
    if (defined(this.expireDate) && this.contentReady && !this.hasEmptyContent) {
      var now = JulianDate.now(scratchJulianDate$1);
      if (JulianDate.lessThan(this.expireDate, now)) {
        this._contentState = Cesium3DTileContentState$1.EXPIRED;
        this._expiredContent = this._content;
      }
    }
  };

  function updateExpireDate(tile) {
    if (defined(tile.expireDuration)) {
      var expireDurationDate = JulianDate.now(scratchJulianDate$1);
      JulianDate.addSeconds(
        expireDurationDate,
        tile.expireDuration,
        expireDurationDate
      );

      if (defined(tile.expireDate)) {
        if (JulianDate.lessThan(tile.expireDate, expireDurationDate)) {
          JulianDate.clone(expireDurationDate, tile.expireDate);
        }
      } else {
        tile.expireDate = JulianDate.clone(expireDurationDate);
      }
    }
  }

  function getContentFailedFunction(tile, tileset) {
    return function (error) {
      if (tile._contentState === Cesium3DTileContentState$1.PROCESSING) {
        --tileset.statistics.numberOfTilesProcessing;
      } else {
        --tileset.statistics.numberOfPendingRequests;
      }
      tile._contentState = Cesium3DTileContentState$1.FAILED;
      tile._contentReadyPromise.reject(error);
      tile._contentReadyToProcessPromise.reject(error);
    };
  }

  function createPriorityFunction(tile) {
    return function () {
      return tile._priority;
    };
  }

  /**
   * Requests the tile's content.
   * <p>
   * The request may not be made if the Cesium Request Scheduler can't prioritize it.
   * </p>
   *
   * @private
   */
  Cesium3DTile.prototype.requestContent = function () {
    var that = this;
    var tileset = this._tileset;

    if (this.hasEmptyContent) {
      return false;
    }

    var resource = this._contentResource.clone();
    var expired = this.contentExpired;
    if (expired) {
      // Append a query parameter of the tile expiration date to prevent caching
      resource.setQueryParameters({
        expired: this.expireDate.toString(),
      });
    }

    var request = new Request({
      throttle: true,
      throttleByServer: true,
      type: RequestType$1.TILES3D,
      priorityFunction: createPriorityFunction(this),
      serverKey: this._serverKey,
    });

    this._request = request;
    resource.request = request;

    var promise = resource.fetchArrayBuffer();

    if (!defined(promise)) {
      return false;
    }

    var contentState = this._contentState;
    this._contentState = Cesium3DTileContentState$1.LOADING;
    this._contentReadyToProcessPromise = when.defer();
    this._contentReadyPromise = when.defer();

    var contentFailedFunction = getContentFailedFunction(this, tileset);
    promise
      .then(function (arrayBuffer) {
        if (that.isDestroyed()) {
          // Tile is unloaded before the content finishes loading
          contentFailedFunction();
          return;
        }
        var uint8Array = new Uint8Array(arrayBuffer);
        var magic = getMagic(uint8Array);
        var contentFactory = Cesium3DTileContentFactory[magic];
        var content;

        // Vector and Geometry tile rendering do not support the skip LOD optimization.
        tileset._disableSkipLevelOfDetail =
          tileset._disableSkipLevelOfDetail ||
          magic === "vctr" ||
          magic === "geom";

        if (defined(contentFactory)) {
          content = contentFactory(
            tileset,
            that,
            that._contentResource,
            arrayBuffer,
            0
          );
        } else {
          // The content may be json instead
          content = Cesium3DTileContentFactory.json(
            tileset,
            that,
            that._contentResource,
            arrayBuffer,
            0
          );
          that.hasTilesetContent = true;
        }

        if (expired) {
          that.expireDate = undefined;
        }

        that._content = content;
        that._contentState = Cesium3DTileContentState$1.PROCESSING;
        that._contentReadyToProcessPromise.resolve(content);

        return content.readyPromise.then(function (content) {
          if (that.isDestroyed()) {
            // Tile is unloaded before the content finishes processing
            contentFailedFunction();
            return;
          }
          updateExpireDate(that);

          // Refresh style for expired content
          that._selectedFrame = 0;
          that.lastStyleTime = 0.0;

          JulianDate.now(that._loadTimestamp);
          that._contentState = Cesium3DTileContentState$1.READY;
          that._contentReadyPromise.resolve(content);
        });
      })
      .otherwise(function (error) {
        if (request.state === RequestState$1.CANCELLED) {
          // Cancelled due to low priority - try again later.
          that._contentState = contentState;
          --tileset.statistics.numberOfPendingRequests;
          ++tileset.statistics.numberOfAttemptedRequests;
          return;
        }
        contentFailedFunction(error);
      });

    return true;
  };

  /**
   * Unloads the tile's content.
   *
   * @private
   */
  Cesium3DTile.prototype.unloadContent = function () {
    if (this.hasEmptyContent || this.hasTilesetContent) {
      return;
    }

    this._content = this._content && this._content.destroy();
    this._contentState = Cesium3DTileContentState$1.UNLOADED;
    this._contentReadyToProcessPromise = undefined;
    this._contentReadyPromise = undefined;

    this.lastStyleTime = 0.0;
    this.clippingPlanesDirty = this._clippingPlanesState === 0;
    this._clippingPlanesState = 0;

    this._debugColorizeTiles = false;

    this._debugBoundingVolume =
      this._debugBoundingVolume && this._debugBoundingVolume.destroy();
    this._debugContentBoundingVolume =
      this._debugContentBoundingVolume &&
      this._debugContentBoundingVolume.destroy();
    this._debugViewerRequestVolume =
      this._debugViewerRequestVolume && this._debugViewerRequestVolume.destroy();
  };

  var scratchProjectedBoundingSphere = new BoundingSphere();

  function getBoundingVolume(tile, frameState) {
    if (
      frameState.mode !== SceneMode$1.SCENE3D &&
      !defined(tile._boundingVolume2D)
    ) {
      var boundingSphere = tile._boundingVolume.boundingSphere;
      var sphere = BoundingSphere.projectTo2D(
        boundingSphere,
        frameState.mapProjection,
        scratchProjectedBoundingSphere
      );
      tile._boundingVolume2D = new TileBoundingSphere(
        sphere.center,
        sphere.radius
      );
    }

    return frameState.mode !== SceneMode$1.SCENE3D
      ? tile._boundingVolume2D
      : tile._boundingVolume;
  }

  function getContentBoundingVolume(tile, frameState) {
    if (
      frameState.mode !== SceneMode$1.SCENE3D &&
      !defined(tile._contentBoundingVolume2D)
    ) {
      var boundingSphere = tile._contentBoundingVolume.boundingSphere;
      var sphere = BoundingSphere.projectTo2D(
        boundingSphere,
        frameState.mapProjection,
        scratchProjectedBoundingSphere
      );
      tile._contentBoundingVolume2D = new TileBoundingSphere(
        sphere.center,
        sphere.radius
      );
    }
    return frameState.mode !== SceneMode$1.SCENE3D
      ? tile._contentBoundingVolume2D
      : tile._contentBoundingVolume;
  }

  /**
   * Determines whether the tile's bounding volume intersects the culling volume.
   *
   * @param {FrameState} frameState The frame state.
   * @param {Number} parentVisibilityPlaneMask The parent's plane mask to speed up the visibility check.
   * @returns {Number} A plane mask as described above in {@link CullingVolume#computeVisibilityWithPlaneMask}.
   *
   * @private
   */
  Cesium3DTile.prototype.visibility = function (
    frameState,
    parentVisibilityPlaneMask
  ) {
    var cullingVolume = frameState.cullingVolume;
    var boundingVolume = getBoundingVolume(this, frameState);

    var tileset = this._tileset;
    var clippingPlanes = tileset.clippingPlanes;
    if (defined(clippingPlanes) && clippingPlanes.enabled) {
      var intersection = clippingPlanes.computeIntersectionWithBoundingVolume(
        boundingVolume,
        tileset.clippingPlanesOriginMatrix
      );
      this._isClipped = intersection !== Intersect$1.INSIDE;
      if (intersection === Intersect$1.OUTSIDE) {
        return CullingVolume.MASK_OUTSIDE;
      }
    }

    return cullingVolume.computeVisibilityWithPlaneMask(
      boundingVolume,
      parentVisibilityPlaneMask
    );
  };

  /**
   * Assuming the tile's bounding volume intersects the culling volume, determines
   * whether the tile's content's bounding volume intersects the culling volume.
   *
   * @param {FrameState} frameState The frame state.
   * @returns {Intersect} The result of the intersection: the tile's content is completely outside, completely inside, or intersecting the culling volume.
   *
   * @private
   */
  Cesium3DTile.prototype.contentVisibility = function (frameState) {
    // Assumes the tile's bounding volume intersects the culling volume already, so
    // just return Intersect.INSIDE if there is no content bounding volume.
    if (!defined(this._contentBoundingVolume)) {
      return Intersect$1.INSIDE;
    }

    if (this._visibilityPlaneMask === CullingVolume.MASK_INSIDE) {
      // The tile's bounding volume is completely inside the culling volume so
      // the content bounding volume must also be inside.
      return Intersect$1.INSIDE;
    }

    // PERFORMANCE_IDEA: is it possible to burn less CPU on this test since we know the
    // tile's (not the content's) bounding volume intersects the culling volume?
    var cullingVolume = frameState.cullingVolume;
    var boundingVolume = getContentBoundingVolume(this, frameState);

    var tileset = this._tileset;
    var clippingPlanes = tileset.clippingPlanes;
    if (defined(clippingPlanes) && clippingPlanes.enabled) {
      var intersection = clippingPlanes.computeIntersectionWithBoundingVolume(
        boundingVolume,
        tileset.clippingPlanesOriginMatrix
      );
      this._isClipped = intersection !== Intersect$1.INSIDE;
      if (intersection === Intersect$1.OUTSIDE) {
        return Intersect$1.OUTSIDE;
      }
    }

    return cullingVolume.computeVisibility(boundingVolume);
  };

  /**
   * Computes the (potentially approximate) distance from the closest point of the tile's bounding volume to the camera.
   *
   * @param {FrameState} frameState The frame state.
   * @returns {Number} The distance, in meters, or zero if the camera is inside the bounding volume.
   *
   * @private
   */
  Cesium3DTile.prototype.distanceToTile = function (frameState) {
    var boundingVolume = getBoundingVolume(this, frameState);
    return boundingVolume.distanceToCamera(frameState);
  };

  var scratchToTileCenter = new Cartesian3();

  /**
   * Computes the distance from the center of the tile's bounding volume to the camera's plane defined by its position and view direction.
   *
   * @param {FrameState} frameState The frame state.
   * @returns {Number} The distance, in meters.
   *
   * @private
   */
  Cesium3DTile.prototype.distanceToTileCenter = function (frameState) {
    var tileBoundingVolume = getBoundingVolume(this, frameState);
    var boundingVolume = tileBoundingVolume.boundingVolume; // Gets the underlying OrientedBoundingBox or BoundingSphere
    var toCenter = Cartesian3.subtract(
      boundingVolume.center,
      frameState.camera.positionWC,
      scratchToTileCenter
    );
    return Cartesian3.dot(frameState.camera.directionWC, toCenter);
  };

  /**
   * Checks if the camera is inside the viewer request volume.
   *
   * @param {FrameState} frameState The frame state.
   * @returns {Boolean} Whether the camera is inside the volume.
   *
   * @private
   */
  Cesium3DTile.prototype.insideViewerRequestVolume = function (frameState) {
    var viewerRequestVolume = this._viewerRequestVolume;
    return (
      !defined(viewerRequestVolume) ||
      viewerRequestVolume.distanceToCamera(frameState) === 0.0
    );
  };

  var scratchMatrix$2 = new Matrix3();
  var scratchScale$6 = new Cartesian3();
  var scratchHalfAxes = new Matrix3();
  var scratchCenter$3 = new Cartesian3();
  var scratchRectangle$2 = new Rectangle();
  var scratchOrientedBoundingBox = new OrientedBoundingBox();
  var scratchTransform = new Matrix4();

  function createBox(box, transform, result) {
    var center = Cartesian3.fromElements(box[0], box[1], box[2], scratchCenter$3);
    var halfAxes = Matrix3.fromArray(box, 3, scratchHalfAxes);

    // Find the transformed center and halfAxes
    center = Matrix4.multiplyByPoint(transform, center, center);
    var rotationScale = Matrix4.getMatrix3(transform, scratchMatrix$2);
    halfAxes = Matrix3.multiply(rotationScale, halfAxes, halfAxes);

    if (defined(result)) {
      result.update(center, halfAxes);
      return result;
    }
    return new TileOrientedBoundingBox(center, halfAxes);
  }

  function createBoxFromTransformedRegion(
    region,
    transform,
    initialTransform,
    result
  ) {
    var rectangle = Rectangle.unpack(region, 0, scratchRectangle$2);
    var minimumHeight = region[4];
    var maximumHeight = region[5];

    var orientedBoundingBox = OrientedBoundingBox.fromRectangle(
      rectangle,
      minimumHeight,
      maximumHeight,
      Ellipsoid.WGS84,
      scratchOrientedBoundingBox
    );
    var center = orientedBoundingBox.center;
    var halfAxes = orientedBoundingBox.halfAxes;

    // A region bounding volume is not transformed by the transform in the tileset JSON,
    // but may be transformed by additional transforms applied in Cesium.
    // This is why the transform is calculated as the difference between the initial transform and the current transform.
    transform = Matrix4.multiplyTransformation(
      transform,
      Matrix4.inverseTransformation(initialTransform, scratchTransform),
      scratchTransform
    );
    center = Matrix4.multiplyByPoint(transform, center, center);
    var rotationScale = Matrix4.getMatrix3(transform, scratchMatrix$2);
    halfAxes = Matrix3.multiply(rotationScale, halfAxes, halfAxes);

    if (defined(result) && result instanceof TileOrientedBoundingBox) {
      result.update(center, halfAxes);
      return result;
    }

    return new TileOrientedBoundingBox(center, halfAxes);
  }

  function createRegion(region, transform, initialTransform, result) {
    if (
      !Matrix4.equalsEpsilon(transform, initialTransform, CesiumMath.EPSILON8)
    ) {
      return createBoxFromTransformedRegion(
        region,
        transform,
        initialTransform,
        result
      );
    }

    if (defined(result)) {
      return result;
    }

    var rectangleRegion = Rectangle.unpack(region, 0, scratchRectangle$2);

    return new TileBoundingRegion({
      rectangle: rectangleRegion,
      minimumHeight: region[4],
      maximumHeight: region[5],
    });
  }

  function createSphere(sphere, transform, result) {
    var center = Cartesian3.fromElements(
      sphere[0],
      sphere[1],
      sphere[2],
      scratchCenter$3
    );
    var radius = sphere[3];

    // Find the transformed center and radius
    center = Matrix4.multiplyByPoint(transform, center, center);
    var scale = Matrix4.getScale(transform, scratchScale$6);
    var uniformScale = Cartesian3.maximumComponent(scale);
    radius *= uniformScale;

    if (defined(result)) {
      result.update(center, radius);
      return result;
    }
    return new TileBoundingSphere(center, radius);
  }

  /**
   * Create a bounding volume from the tile's bounding volume header.
   *
   * @param {Object} boundingVolumeHeader The tile's bounding volume header.
   * @param {Matrix4} transform The transform to apply to the bounding volume.
   * @param {TileBoundingVolume} [result] The object onto which to store the result.
   *
   * @returns {TileBoundingVolume} The modified result parameter or a new TileBoundingVolume instance if none was provided.
   *
   * @private
   */
  Cesium3DTile.prototype.createBoundingVolume = function (
    boundingVolumeHeader,
    transform,
    result
  ) {
    if (!defined(boundingVolumeHeader)) {
      throw new RuntimeError("boundingVolume must be defined");
    }
    if (defined(boundingVolumeHeader.box)) {
      return createBox(boundingVolumeHeader.box, transform, result);
    }
    if (defined(boundingVolumeHeader.region)) {
      return createRegion(
        boundingVolumeHeader.region,
        transform,
        this._initialTransform,
        result
      );
    }
    if (defined(boundingVolumeHeader.sphere)) {
      return createSphere(boundingVolumeHeader.sphere, transform, result);
    }
    throw new RuntimeError(
      "boundingVolume must contain a sphere, region, or box"
    );
  };

  /**
   * Update the tile's transform. The transform is applied to the tile's bounding volumes.
   *
   * @private
   */
  Cesium3DTile.prototype.updateTransform = function (parentTransform) {
    parentTransform = defaultValue(parentTransform, Matrix4.IDENTITY);
    var computedTransform = Matrix4.multiply(
      parentTransform,
      this.transform,
      scratchTransform
    );
    var transformChanged = !Matrix4.equals(
      computedTransform,
      this.computedTransform
    );

    if (!transformChanged) {
      return;
    }

    Matrix4.clone(computedTransform, this.computedTransform);

    // Update the bounding volumes
    var header = this._header;
    var content = this._header.content;
    this._boundingVolume = this.createBoundingVolume(
      header.boundingVolume,
      this.computedTransform,
      this._boundingVolume
    );
    if (defined(this._contentBoundingVolume)) {
      this._contentBoundingVolume = this.createBoundingVolume(
        content.boundingVolume,
        this.computedTransform,
        this._contentBoundingVolume
      );
    }
    if (defined(this._viewerRequestVolume)) {
      this._viewerRequestVolume = this.createBoundingVolume(
        header.viewerRequestVolume,
        this.computedTransform,
        this._viewerRequestVolume
      );
    }

    this.updateGeometricErrorScale();

    // Destroy the debug bounding volumes. They will be generated fresh.
    this._debugBoundingVolume =
      this._debugBoundingVolume && this._debugBoundingVolume.destroy();
    this._debugContentBoundingVolume =
      this._debugContentBoundingVolume &&
      this._debugContentBoundingVolume.destroy();
    this._debugViewerRequestVolume =
      this._debugViewerRequestVolume && this._debugViewerRequestVolume.destroy();
  };

  Cesium3DTile.prototype.updateGeometricErrorScale = function () {
    var scale = Matrix4.getScale(this.computedTransform, scratchScale$6);
    var uniformScale = Cartesian3.maximumComponent(scale);
    this.geometricError = this._geometricError * uniformScale;
  };

  function applyDebugSettings(tile, tileset, frameState, passOptions) {
    if (!passOptions.isRender) {
      return;
    }

    var hasContentBoundingVolume =
      defined(tile._header.content) &&
      defined(tile._header.content.boundingVolume);
    var empty = tile.hasEmptyContent || tile.hasTilesetContent;

    var showVolume =
      tileset.debugShowBoundingVolume ||
      (tileset.debugShowContentBoundingVolume && !hasContentBoundingVolume);
    if (showVolume) {
      var color;
      if (!tile._finalResolution) {
        color = Color.YELLOW;
      } else if (empty) {
        color = Color.DARKGRAY;
      } else {
        color = Color.WHITE;
      }
      if (!defined(tile._debugBoundingVolume)) {
        tile._debugBoundingVolume = tile._boundingVolume.createDebugVolume(color);
      }
      tile._debugBoundingVolume.update(frameState);
      var attributes = tile._debugBoundingVolume.getGeometryInstanceAttributes(
        "outline"
      );
      attributes.color = ColorGeometryInstanceAttribute.toValue(
        color,
        attributes.color
      );
    } else if (!showVolume && defined(tile._debugBoundingVolume)) {
      tile._debugBoundingVolume = tile._debugBoundingVolume.destroy();
    }

    if (tileset.debugShowContentBoundingVolume && hasContentBoundingVolume) {
      if (!defined(tile._debugContentBoundingVolume)) {
        tile._debugContentBoundingVolume = tile._contentBoundingVolume.createDebugVolume(
          Color.BLUE
        );
      }
      tile._debugContentBoundingVolume.update(frameState);
    } else if (
      !tileset.debugShowContentBoundingVolume &&
      defined(tile._debugContentBoundingVolume)
    ) {
      tile._debugContentBoundingVolume = tile._debugContentBoundingVolume.destroy();
    }

    if (
      tileset.debugShowViewerRequestVolume &&
      defined(tile._viewerRequestVolume)
    ) {
      if (!defined(tile._debugViewerRequestVolume)) {
        tile._debugViewerRequestVolume = tile._viewerRequestVolume.createDebugVolume(
          Color.YELLOW
        );
      }
      tile._debugViewerRequestVolume.update(frameState);
    } else if (
      !tileset.debugShowViewerRequestVolume &&
      defined(tile._debugViewerRequestVolume)
    ) {
      tile._debugViewerRequestVolume = tile._debugViewerRequestVolume.destroy();
    }

    var debugColorizeTilesOn =
      (tileset.debugColorizeTiles && !tile._debugColorizeTiles) ||
      defined(tileset._heatmap.tilePropertyName);
    var debugColorizeTilesOff =
      !tileset.debugColorizeTiles && tile._debugColorizeTiles;

    if (debugColorizeTilesOn) {
      tileset._heatmap.colorize(tile, frameState); // Skipped if tileset._heatmap.tilePropertyName is undefined
      tile._debugColorizeTiles = true;
      tile.color = tile._debugColor;
    } else if (debugColorizeTilesOff) {
      tile._debugColorizeTiles = false;
      tile.color = Color.WHITE;
    }

    if (tile._colorDirty) {
      tile._colorDirty = false;
      tile._content.applyDebugSettings(true, tile._color);
    }

    if (debugColorizeTilesOff) {
      tileset.makeStyleDirty(); // Re-apply style now that colorize is switched off
    }
  }

  function updateContent(tile, tileset, frameState) {
    var content = tile._content;
    var expiredContent = tile._expiredContent;

    if (defined(expiredContent)) {
      if (!tile.contentReady) {
        // Render the expired content while the content loads
        expiredContent.update(tileset, frameState);
        return;
      }

      // New content is ready, destroy expired content
      tile._expiredContent.destroy();
      tile._expiredContent = undefined;
    }

    content.update(tileset, frameState);
  }

  function updateClippingPlanes$1(tile, tileset) {
    // Compute and compare ClippingPlanes state:
    // - enabled-ness - are clipping planes enabled? is this tile clipped?
    // - clipping plane count
    // - clipping function (union v. intersection)
    var clippingPlanes = tileset.clippingPlanes;
    var currentClippingPlanesState = 0;
    if (defined(clippingPlanes) && tile._isClipped && clippingPlanes.enabled) {
      currentClippingPlanesState = clippingPlanes.clippingPlanesState;
    }
    // If clippingPlaneState for tile changed, mark clippingPlanesDirty so content can update
    if (currentClippingPlanesState !== tile._clippingPlanesState) {
      tile._clippingPlanesState = currentClippingPlanesState;
      tile.clippingPlanesDirty = true;
    }
  }

  /**
   * Get the draw commands needed to render this tile.
   *
   * @private
   */
  Cesium3DTile.prototype.update = function (tileset, frameState, passOptions) {
    var initCommandLength = frameState.commandList.length;
    updateClippingPlanes$1(this, tileset);
    applyDebugSettings(this, tileset, frameState, passOptions);
    updateContent(this, tileset, frameState);
    this._commandsLength = frameState.commandList.length - initCommandLength;

    this.clippingPlanesDirty = false; // reset after content update
  };

  var scratchCommandList = [];

  /**
   * Processes the tile's content, e.g., create WebGL resources, to move from the PROCESSING to READY state.
   *
   * @param {Cesium3DTileset} tileset The tileset containing this tile.
   * @param {FrameState} frameState The frame state.
   *
   * @private
   */
  Cesium3DTile.prototype.process = function (tileset, frameState) {
    var savedCommandList = frameState.commandList;
    frameState.commandList = scratchCommandList;

    this._content.update(tileset, frameState);

    scratchCommandList.length = 0;
    frameState.commandList = savedCommandList;
  };

  function isolateDigits(normalizedValue, numberOfDigits, leftShift) {
    var scaled = normalizedValue * Math.pow(10, numberOfDigits);
    var integer = parseInt(scaled);
    return integer * Math.pow(10, leftShift);
  }

  function priorityNormalizeAndClamp(value, minimum, maximum) {
    return Math.max(
      CesiumMath.normalize(value, minimum, maximum) - CesiumMath.EPSILON7,
      0.0
    ); // Subtract epsilon since we only want decimal digits present in the output.
  }

  /**
   * Sets the priority of the tile based on distance and depth
   * @private
   */
  Cesium3DTile.prototype.updatePriority = function () {
    var tileset = this.tileset;
    var preferLeaves = tileset.preferLeaves;
    var minimumPriority = tileset._minimumPriority;
    var maximumPriority = tileset._maximumPriority;

    // Combine priority systems together by mapping them into a base 10 number where each priority controls a specific set of digits in the number.
    // For number priorities, map them to a 0.xxxxx number then left shift it up into a set number of digits before the decimal point. Chop of the fractional part then left shift again into the position it needs to go.
    // For blending number priorities, normalize them to 0-1 and interpolate to get a combined 0-1 number, then proceed as normal.
    // Booleans can just be 0 or 10^leftshift.
    // Think of digits as penalties since smaller numbers are higher priority. If a tile has some large quantity or has a flag raised it's (usually) penalized for it, expressed as a higher number for the digit.
    // Priority number format: preloadFlightDigits(1) | foveatedDeferDigits(1) | foveatedDigits(4) | preloadProgressiveResolutionDigits(1) | preferredSortingDigits(4) . depthDigits(the decimal digits)
    // Certain flags like preferLeaves will flip / turn off certain digits to get desired load order.

    // Setup leftShifts, digit counts, and scales (for booleans)
    var digitsForANumber = 4;
    var digitsForABoolean = 1;

    var preferredSortingLeftShift = 0;
    var preferredSortingDigitsCount = digitsForANumber;

    var foveatedLeftShift =
      preferredSortingLeftShift + preferredSortingDigitsCount;
    var foveatedDigitsCount = digitsForANumber;

    var preloadProgressiveResolutionLeftShift =
      foveatedLeftShift + foveatedDigitsCount;
    var preloadProgressiveResolutionDigitsCount = digitsForABoolean;
    var preloadProgressiveResolutionScale = Math.pow(
      10,
      preloadProgressiveResolutionLeftShift
    );

    var foveatedDeferLeftShift =
      preloadProgressiveResolutionLeftShift +
      preloadProgressiveResolutionDigitsCount;
    var foveatedDeferDigitsCount = digitsForABoolean;
    var foveatedDeferScale = Math.pow(10, foveatedDeferLeftShift);

    var preloadFlightLeftShift =
      foveatedDeferLeftShift + foveatedDeferDigitsCount;
    var preloadFlightScale = Math.pow(10, preloadFlightLeftShift);

    // Compute the digits for each priority
    var depthDigits = priorityNormalizeAndClamp(
      this._depth,
      minimumPriority.depth,
      maximumPriority.depth
    );
    depthDigits = preferLeaves ? 1.0 - depthDigits : depthDigits;

    // Map 0-1 then convert to digit. Include a distance sort when doing non-skipLOD and replacement refinement, helps things like non-skipLOD photogrammetry
    var useDistance =
      !tileset._skipLevelOfDetail && this.refine === Cesium3DTileRefine$1.REPLACE;
    var normalizedPreferredSorting = useDistance
      ? priorityNormalizeAndClamp(
          this._priorityHolder._distanceToCamera,
          minimumPriority.distance,
          maximumPriority.distance
        )
      : priorityNormalizeAndClamp(
          this._priorityReverseScreenSpaceError,
          minimumPriority.reverseScreenSpaceError,
          maximumPriority.reverseScreenSpaceError
        );
    var preferredSortingDigits = isolateDigits(
      normalizedPreferredSorting,
      preferredSortingDigitsCount,
      preferredSortingLeftShift
    );

    var preloadProgressiveResolutionDigits = this._priorityProgressiveResolution
      ? 0
      : preloadProgressiveResolutionScale;

    var normalizedFoveatedFactor = priorityNormalizeAndClamp(
      this._priorityHolder._foveatedFactor,
      minimumPriority.foveatedFactor,
      maximumPriority.foveatedFactor
    );
    var foveatedDigits = isolateDigits(
      normalizedFoveatedFactor,
      foveatedDigitsCount,
      foveatedLeftShift
    );

    var foveatedDeferDigits = this.priorityDeferred ? foveatedDeferScale : 0;

    var preloadFlightDigits =
      tileset._pass === Cesium3DTilePass$1.PRELOAD_FLIGHT ? 0 : preloadFlightScale;

    // Get the final base 10 number
    this._priority =
      depthDigits +
      preferredSortingDigits +
      preloadProgressiveResolutionDigits +
      foveatedDigits +
      foveatedDeferDigits +
      preloadFlightDigits;
  };

  /**
   * @private
   */
  Cesium3DTile.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * @private
   */
  Cesium3DTile.prototype.destroy = function () {
    // For the interval between new content being requested and downloaded, expiredContent === content, so don't destroy twice
    this._content = this._content && this._content.destroy();
    this._expiredContent =
      this._expiredContent &&
      !this._expiredContent.isDestroyed() &&
      this._expiredContent.destroy();
    this._debugBoundingVolume =
      this._debugBoundingVolume && this._debugBoundingVolume.destroy();
    this._debugContentBoundingVolume =
      this._debugContentBoundingVolume &&
      this._debugContentBoundingVolume.destroy();
    this._debugViewerRequestVolume =
      this._debugViewerRequestVolume && this._debugViewerRequestVolume.destroy();
    return destroyObject(this);
  };

  /**
   * Utility functions for computing optimization hints for a {@link Cesium3DTileset}.
   *
   * @namespace Cesium3DTileOptimizations
   *
   * @private
   */
  var Cesium3DTileOptimizations = {};

  var scratchAxis = new Cartesian3();

  /**
   * Evaluates support for the childrenWithinParent optimization. This is used to more tightly cull tilesets if
   * children bounds are fully contained within the parent. Currently, support for the optimization only works for
   * oriented bounding boxes, so both the child and parent tile must be either a {@link TileOrientedBoundingBox} or
   * {@link TileBoundingRegion}. The purpose of this check is to prevent use of a culling optimization when the child
   * bounds exceed those of the parent. If the child bounds are greater, it is more likely that the optimization will
   * waste CPU cycles. Bounding spheres are not supported for the reason that the child bounds can very often be
   * partially outside of the parent bounds.
   *
   * @param {Cesium3DTile} tile The tile to check.
   * @returns {Boolean} Whether the childrenWithinParent optimization is supported.
   */
  Cesium3DTileOptimizations.checkChildrenWithinParent = function (tile) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("tile", tile);
    //>>includeEnd('debug');

    var children = tile.children;
    var length = children.length;

    // Check if the parent has an oriented bounding box.
    var boundingVolume = tile.boundingVolume;
    if (
      boundingVolume instanceof TileOrientedBoundingBox ||
      boundingVolume instanceof TileBoundingRegion
    ) {
      var orientedBoundingBox = boundingVolume._orientedBoundingBox;
      tile._optimChildrenWithinParent =
        Cesium3DTileOptimizationHint$1.USE_OPTIMIZATION;
      for (var i = 0; i < length; ++i) {
        var child = children[i];

        // Check if the child has an oriented bounding box.
        var childBoundingVolume = child.boundingVolume;
        if (
          !(
            childBoundingVolume instanceof TileOrientedBoundingBox ||
            childBoundingVolume instanceof TileBoundingRegion
          )
        ) {
          // Do not support if the parent and child both do not have oriented bounding boxes.
          tile._optimChildrenWithinParent =
            Cesium3DTileOptimizationHint$1.SKIP_OPTIMIZATION;
          break;
        }

        var childOrientedBoundingBox = childBoundingVolume._orientedBoundingBox;

        // Compute the axis from the parent to the child.
        var axis = Cartesian3.subtract(
          childOrientedBoundingBox.center,
          orientedBoundingBox.center,
          scratchAxis
        );
        var axisLength = Cartesian3.magnitude(axis);
        Cartesian3.divideByScalar(axis, axisLength, axis);

        // Project the bounding box of the parent onto the axis. Because the axis is a ray from the parent
        // to the child, the projection parameterized along the ray will be (+/- proj1).
        var proj1 =
          Math.abs(orientedBoundingBox.halfAxes[0] * axis.x) +
          Math.abs(orientedBoundingBox.halfAxes[1] * axis.y) +
          Math.abs(orientedBoundingBox.halfAxes[2] * axis.z) +
          Math.abs(orientedBoundingBox.halfAxes[3] * axis.x) +
          Math.abs(orientedBoundingBox.halfAxes[4] * axis.y) +
          Math.abs(orientedBoundingBox.halfAxes[5] * axis.z) +
          Math.abs(orientedBoundingBox.halfAxes[6] * axis.x) +
          Math.abs(orientedBoundingBox.halfAxes[7] * axis.y) +
          Math.abs(orientedBoundingBox.halfAxes[8] * axis.z);

        // Project the bounding box of the child onto the axis. Because the axis is a ray from the parent
        // to the child, the projection parameterized along the ray will be (+/- proj2) + axis.length.
        var proj2 =
          Math.abs(childOrientedBoundingBox.halfAxes[0] * axis.x) +
          Math.abs(childOrientedBoundingBox.halfAxes[1] * axis.y) +
          Math.abs(childOrientedBoundingBox.halfAxes[2] * axis.z) +
          Math.abs(childOrientedBoundingBox.halfAxes[3] * axis.x) +
          Math.abs(childOrientedBoundingBox.halfAxes[4] * axis.y) +
          Math.abs(childOrientedBoundingBox.halfAxes[5] * axis.z) +
          Math.abs(childOrientedBoundingBox.halfAxes[6] * axis.x) +
          Math.abs(childOrientedBoundingBox.halfAxes[7] * axis.y) +
          Math.abs(childOrientedBoundingBox.halfAxes[8] * axis.z);

        // If the child extends the parent's bounds, the optimization is not valid and we skip it.
        if (proj1 <= proj2 + axisLength) {
          tile._optimChildrenWithinParent =
            Cesium3DTileOptimizationHint$1.SKIP_OPTIMIZATION;
          break;
        }
      }
    }

    return (
      tile._optimChildrenWithinParent ===
      Cesium3DTileOptimizationHint$1.USE_OPTIMIZATION
    );
  };

  /**
   * Stores tiles with content loaded.
   *
   * @private
   */
  function Cesium3DTilesetCache() {
    // [head, sentinel) -> tiles that weren't selected this frame and may be removed from the cache
    // (sentinel, tail] -> tiles that were selected this frame
    this._list = new DoublyLinkedList();
    this._sentinel = this._list.add();
    this._trimTiles = false;
  }

  Cesium3DTilesetCache.prototype.reset = function () {
    // Move sentinel node to the tail so, at the start of the frame, all tiles
    // may be potentially replaced.  Tiles are moved to the right of the sentinel
    // when they are selected so they will not be replaced.
    this._list.splice(this._list.tail, this._sentinel);
  };

  Cesium3DTilesetCache.prototype.touch = function (tile) {
    var node = tile.cacheNode;
    if (defined(node)) {
      this._list.splice(this._sentinel, node);
    }
  };

  Cesium3DTilesetCache.prototype.add = function (tile) {
    if (!defined(tile.cacheNode)) {
      tile.cacheNode = this._list.add(tile);
    }
  };

  Cesium3DTilesetCache.prototype.unloadTile = function (
    tileset,
    tile,
    unloadCallback
  ) {
    var node = tile.cacheNode;
    if (!defined(node)) {
      return;
    }

    this._list.remove(node);
    tile.cacheNode = undefined;
    unloadCallback(tileset, tile);
  };

  Cesium3DTilesetCache.prototype.unloadTiles = function (
    tileset,
    unloadCallback
  ) {
    var trimTiles = this._trimTiles;
    this._trimTiles = false;

    var list = this._list;

    var maximumMemoryUsageInBytes = tileset.maximumMemoryUsage * 1024 * 1024;

    // Traverse the list only to the sentinel since tiles/nodes to the
    // right of the sentinel were used this frame.
    //
    // The sub-list to the left of the sentinel is ordered from LRU to MRU.
    var sentinel = this._sentinel;
    var node = list.head;
    while (
      node !== sentinel &&
      (tileset.totalMemoryUsageInBytes > maximumMemoryUsageInBytes || trimTiles)
    ) {
      var tile = node.item;
      node = node.next;
      this.unloadTile(tileset, tile, unloadCallback);
    }
  };

  Cesium3DTilesetCache.prototype.trim = function () {
    this._trimTiles = true;
  };

  /**
   * A heatmap colorizer in a {@link Cesium3DTileset}. A tileset can colorize its visible tiles in a heatmap style.
   *
   * @alias Cesium3DTilesetHeatmap
   * @constructor
   * @private
   */
  function Cesium3DTilesetHeatmap(tilePropertyName) {
    /**
     * The tile variable to track for heatmap colorization.
     * Tile's will be colorized relative to the other visible tile's values for this variable.
     *
     * @type {String}
     */
    this.tilePropertyName = tilePropertyName;

    // Members that are updated every time a tile is colorized
    this._minimum = Number.MAX_VALUE;
    this._maximum = -Number.MAX_VALUE;

    // Members that are updated once every frame
    this._previousMinimum = Number.MAX_VALUE;
    this._previousMaximum = -Number.MAX_VALUE;

    // If defined uses a reference minimum maximum to colorize by instead of using last frames minimum maximum of rendered tiles.
    // For example, the _loadTimestamp can get a better colorization using setReferenceMinimumMaximum in order to take accurate colored timing diffs of various scenes.
    this._referenceMinimum = {};
    this._referenceMaximum = {};
  }

  /**
   * Convert to a usable heatmap value (i.e. a number). Ensures that tile values that aren't stored as numbers can be used for colorization.
   * @private
   */
  function getHeatmapValue(tileValue, tilePropertyName) {
    var value;
    if (tilePropertyName === "_loadTimestamp") {
      value = JulianDate.toDate(tileValue).getTime();
    } else {
      value = tileValue;
    }
    return value;
  }

  /**
   * Sets the reference minimum and maximum for the variable name. Converted to numbers before they are stored.
   *
   * @param {Object} minimum The minimum reference value.
   * @param {Object} maximum The maximum reference value.
   * @param {String} tilePropertyName The tile variable that will use these reference values when it is colorized.
   */
  Cesium3DTilesetHeatmap.prototype.setReferenceMinimumMaximum = function (
    minimum,
    maximum,
    tilePropertyName
  ) {
    this._referenceMinimum[tilePropertyName] = getHeatmapValue(
      minimum,
      tilePropertyName
    );
    this._referenceMaximum[tilePropertyName] = getHeatmapValue(
      maximum,
      tilePropertyName
    );
  };

  function getHeatmapValueAndUpdateMinimumMaximum(heatmap, tile) {
    var tilePropertyName = heatmap.tilePropertyName;
    if (defined(tilePropertyName)) {
      var heatmapValue = getHeatmapValue(
        tile[tilePropertyName],
        tilePropertyName
      );
      if (!defined(heatmapValue)) {
        heatmap.tilePropertyName = undefined;
        return heatmapValue;
      }
      heatmap._maximum = Math.max(heatmapValue, heatmap._maximum);
      heatmap._minimum = Math.min(heatmapValue, heatmap._minimum);
      return heatmapValue;
    }
  }

  var heatmapColors = [
    new Color(0.1, 0.1, 0.1, 1), // Dark Gray
    new Color(0.153, 0.278, 0.878, 1), // Blue
    new Color(0.827, 0.231, 0.49, 1), // Pink
    new Color(0.827, 0.188, 0.22, 1), // Red
    new Color(1.0, 0.592, 0.259, 1), // Orange
    new Color(1.0, 0.843, 0.0, 1),
  ]; // Yellow
  /**
   * Colorize the tile in heat map style based on where it lies within the minimum maximum window.
   * Heatmap colors are black, blue, pink, red, orange, yellow. 'Cold' or low numbers will be black and blue, 'Hot' or high numbers will be orange and yellow,
   * @param {Cesium3DTile} tile The tile to colorize relative to last frame's minimum and maximum values of all visible tiles.
   * @param {FrameState} frameState The frame state.
   */
  Cesium3DTilesetHeatmap.prototype.colorize = function (tile, frameState) {
    var tilePropertyName = this.tilePropertyName;
    if (
      !defined(tilePropertyName) ||
      !tile.contentAvailable ||
      tile._selectedFrame !== frameState.frameNumber
    ) {
      return;
    }

    var heatmapValue = getHeatmapValueAndUpdateMinimumMaximum(this, tile);
    var minimum = this._previousMinimum;
    var maximum = this._previousMaximum;

    if (minimum === Number.MAX_VALUE || maximum === -Number.MAX_VALUE) {
      return;
    }

    // Shift the minimum maximum window down to 0
    var shiftedMax = maximum - minimum + CesiumMath.EPSILON7; // Prevent divide by 0
    var shiftedValue = CesiumMath.clamp(heatmapValue - minimum, 0.0, shiftedMax);

    // Get position between minimum and maximum and convert that to a position in the color array
    var zeroToOne = shiftedValue / shiftedMax;
    var lastIndex = heatmapColors.length - 1.0;
    var colorPosition = zeroToOne * lastIndex;

    // Take floor and ceil of the value to get the two colors to lerp between, lerp using the fractional portion
    var colorPositionFloor = Math.floor(colorPosition);
    var colorPositionCeil = Math.ceil(colorPosition);
    var t = colorPosition - colorPositionFloor;
    var colorZero = heatmapColors[colorPositionFloor];
    var colorOne = heatmapColors[colorPositionCeil];

    // Perform the lerp
    var finalColor = Color.clone(Color.WHITE);
    finalColor.red = CesiumMath.lerp(colorZero.red, colorOne.red, t);
    finalColor.green = CesiumMath.lerp(colorZero.green, colorOne.green, t);
    finalColor.blue = CesiumMath.lerp(colorZero.blue, colorOne.blue, t);
    tile._debugColor = finalColor;
  };

  /**
   * Resets the tracked minimum maximum values for heatmap colorization. Happens right before tileset traversal.
   */
  Cesium3DTilesetHeatmap.prototype.resetMinimumMaximum = function () {
    // For heat map colorization
    var tilePropertyName = this.tilePropertyName;
    if (defined(tilePropertyName)) {
      var referenceMinimum = this._referenceMinimum[tilePropertyName];
      var referenceMaximum = this._referenceMaximum[tilePropertyName];
      var useReference = defined(referenceMinimum) && defined(referenceMaximum);
      this._previousMinimum = useReference ? referenceMinimum : this._minimum;
      this._previousMaximum = useReference ? referenceMaximum : this._maximum;
      this._minimum = Number.MAX_VALUE;
      this._maximum = -Number.MAX_VALUE;
    }
  };

  /**
   * @private
   */
  function Cesium3DTilesetStatistics() {
    // Rendering statistics
    this.selected = 0;
    this.visited = 0;
    // Loading statistics
    this.numberOfCommands = 0;
    this.numberOfAttemptedRequests = 0;
    this.numberOfPendingRequests = 0;
    this.numberOfTilesProcessing = 0;
    this.numberOfTilesWithContentReady = 0; // Number of tiles with content loaded, does not include empty tiles
    this.numberOfTilesTotal = 0; // Number of tiles in tileset JSON (and other tileset JSON files as they are loaded)
    this.numberOfLoadedTilesTotal = 0; // Running total of loaded tiles for the lifetime of the session
    // Features statistics
    this.numberOfFeaturesSelected = 0; // Number of features rendered
    this.numberOfFeaturesLoaded = 0; // Number of features in memory
    this.numberOfPointsSelected = 0;
    this.numberOfPointsLoaded = 0;
    this.numberOfTrianglesSelected = 0;
    // Styling statistics
    this.numberOfTilesStyled = 0;
    this.numberOfFeaturesStyled = 0;
    // Optimization statistics
    this.numberOfTilesCulledWithChildrenUnion = 0;
    // Memory statistics
    this.geometryByteLength = 0;
    this.texturesByteLength = 0;
    this.batchTableByteLength = 0;
  }

  Cesium3DTilesetStatistics.prototype.clear = function () {
    this.selected = 0;
    this.visited = 0;
    this.numberOfCommands = 0;
    this.numberOfAttemptedRequests = 0;
    this.numberOfFeaturesSelected = 0;
    this.numberOfPointsSelected = 0;
    this.numberOfTrianglesSelected = 0;
    this.numberOfTilesStyled = 0;
    this.numberOfFeaturesStyled = 0;
    this.numberOfTilesCulledWithChildrenUnion = 0;
  };

  function updatePointAndFeatureCounts(statistics, content, decrement, load) {
    var contents = content.innerContents;
    var pointsLength = content.pointsLength;
    var trianglesLength = content.trianglesLength;
    var featuresLength = content.featuresLength;
    var geometryByteLength = content.geometryByteLength;
    var texturesByteLength = content.texturesByteLength;
    var batchTableByteLength = content.batchTableByteLength;

    if (load) {
      statistics.numberOfFeaturesLoaded += decrement
        ? -featuresLength
        : featuresLength;
      statistics.numberOfPointsLoaded += decrement ? -pointsLength : pointsLength;
      statistics.geometryByteLength += decrement
        ? -geometryByteLength
        : geometryByteLength;
      statistics.texturesByteLength += decrement
        ? -texturesByteLength
        : texturesByteLength;
      statistics.batchTableByteLength += decrement
        ? -batchTableByteLength
        : batchTableByteLength;
    } else {
      statistics.numberOfFeaturesSelected += decrement
        ? -featuresLength
        : featuresLength;
      statistics.numberOfPointsSelected += decrement
        ? -pointsLength
        : pointsLength;
      statistics.numberOfTrianglesSelected += decrement
        ? -trianglesLength
        : trianglesLength;
    }

    if (defined(contents)) {
      var length = contents.length;
      for (var i = 0; i < length; ++i) {
        updatePointAndFeatureCounts(statistics, contents[i], decrement, load);
      }
    }
  }

  Cesium3DTilesetStatistics.prototype.incrementSelectionCounts = function (
    content
  ) {
    updatePointAndFeatureCounts(this, content, false, false);
  };

  Cesium3DTilesetStatistics.prototype.incrementLoadCounts = function (content) {
    updatePointAndFeatureCounts(this, content, false, true);
  };

  Cesium3DTilesetStatistics.prototype.decrementLoadCounts = function (content) {
    updatePointAndFeatureCounts(this, content, true, true);
  };

  Cesium3DTilesetStatistics.clone = function (statistics, result) {
    result.selected = statistics.selected;
    result.visited = statistics.visited;
    result.numberOfCommands = statistics.numberOfCommands;
    result.selected = statistics.selected;
    result.numberOfAttemptedRequests = statistics.numberOfAttemptedRequests;
    result.numberOfPendingRequests = statistics.numberOfPendingRequests;
    result.numberOfTilesProcessing = statistics.numberOfTilesProcessing;
    result.numberOfTilesWithContentReady =
      statistics.numberOfTilesWithContentReady;
    result.numberOfTilesTotal = statistics.numberOfTilesTotal;
    result.numberOfFeaturesSelected = statistics.numberOfFeaturesSelected;
    result.numberOfFeaturesLoaded = statistics.numberOfFeaturesLoaded;
    result.numberOfPointsSelected = statistics.numberOfPointsSelected;
    result.numberOfPointsLoaded = statistics.numberOfPointsLoaded;
    result.numberOfTrianglesSelected = statistics.numberOfTrianglesSelected;
    result.numberOfTilesStyled = statistics.numberOfTilesStyled;
    result.numberOfFeaturesStyled = statistics.numberOfFeaturesStyled;
    result.numberOfTilesCulledWithChildrenUnion =
      statistics.numberOfTilesCulledWithChildrenUnion;
    result.geometryByteLength = statistics.geometryByteLength;
    result.texturesByteLength = statistics.texturesByteLength;
    result.batchTableByteLength = statistics.batchTableByteLength;
  };

  /**
   * @private
   */
  function Cesium3DTileStyleEngine() {
    this._style = undefined; // The style provided by the user
    this._styleDirty = false; // true when the style is reassigned
    this._lastStyleTime = 0; // The "time" when the last style was assigned
  }

  Object.defineProperties(Cesium3DTileStyleEngine.prototype, {
    style: {
      get: function () {
        return this._style;
      },
      set: function (value) {
        this._style = value;
        this._styleDirty = true;
      },
    },
  });

  Cesium3DTileStyleEngine.prototype.makeDirty = function () {
    this._styleDirty = true;
  };

  Cesium3DTileStyleEngine.prototype.applyStyle = function (tileset, passOptions) {
    if (!tileset.ready) {
      return;
    }

    if (defined(this._style) && !this._style.ready) {
      return;
    }

    var styleDirty = this._styleDirty;

    if (passOptions.isRender) {
      // Don't reset until the render pass
      this._styleDirty = false;
    }

    if (styleDirty) {
      // Increase "time", so the style is applied to all visible tiles
      ++this._lastStyleTime;
    }

    var lastStyleTime = this._lastStyleTime;
    var statistics = tileset._statistics;

    // If a new style was assigned, loop through all the visible tiles; otherwise, loop through
    // only the tiles that are newly visible, i.e., they are visible this frame, but were not
    // visible last frame.  In many cases, the newly selected tiles list will be short or empty.
    var tiles = styleDirty
      ? tileset._selectedTiles
      : tileset._selectedTilesToStyle;
    // PERFORMANCE_IDEA: does mouse-over picking basically trash this?  We need to style on
    // pick, for example, because a feature's show may be false.

    var length = tiles.length;
    for (var i = 0; i < length; ++i) {
      var tile = tiles[i];
      if (tile.lastStyleTime !== lastStyleTime) {
        // Apply the style to this tile if it wasn't already applied because:
        //   1) the user assigned a new style to the tileset
        //   2) this tile is now visible, but it wasn't visible when the style was first assigned
        var content = tile.content;
        tile.lastStyleTime = lastStyleTime;
        content.applyStyle(this._style);
        statistics.numberOfFeaturesStyled += content.featuresLength;
        ++statistics.numberOfTilesStyled;
      }
    }
  };

  /**
   * A {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles tileset},
   * used for streaming massive heterogeneous 3D geospatial datasets.
   *
   * @alias Cesium3DTileset
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String|Promise<Resource>|Promise<String>} options.url The url to a tileset JSON file.
   * @param {Boolean} [options.show=true] Determines if the tileset will be shown.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] A 4x4 transformation matrix that transforms the tileset's root tile.
   * @param {ShadowMode} [options.shadows=ShadowMode.ENABLED] Determines whether the tileset casts or receives shadows from light sources.
   * @param {Number} [options.maximumScreenSpaceError=16] The maximum screen space error used to drive level of detail refinement.
   * @param {Number} [options.maximumMemoryUsage=512] The maximum amount of memory in MB that can be used by the tileset.
   * @param {Boolean} [options.cullWithChildrenBounds=true] Optimization option. Whether to cull tiles using the union of their children bounding volumes.
   * @param {Boolean} [options.cullRequestsWhileMoving=true] Optimization option. Don't request tiles that will likely be unused when they come back because of the camera's movement. This optimization only applies to stationary tilesets.
   * @param {Number} [options.cullRequestsWhileMovingMultiplier=60.0] Optimization option. Multiplier used in culling requests while moving. Larger is more aggressive culling, smaller less aggressive culling.
   * @param {Boolean} [options.preloadWhenHidden=false] Preload tiles when <code>tileset.show</code> is <code>false</code>. Loads tiles as if the tileset is visible but does not render them.
   * @param {Boolean} [options.preloadFlightDestinations=true] Optimization option. Preload tiles at the camera's flight destination while the camera is in flight.
   * @param {Boolean} [options.preferLeaves=false] Optimization option. Prefer loading of leaves first.
   * @param {Boolean} [options.dynamicScreenSpaceError=false] Optimization option. Reduce the screen space error for tiles that are further away from the camera.
   * @param {Number} [options.dynamicScreenSpaceErrorDensity=0.00278] Density used to adjust the dynamic screen space error, similar to fog density.
   * @param {Number} [options.dynamicScreenSpaceErrorFactor=4.0] A factor used to increase the computed dynamic screen space error.
   * @param {Number} [options.dynamicScreenSpaceErrorHeightFalloff=0.25] A ratio of the tileset's height at which the density starts to falloff.
   * @param {Number} [options.progressiveResolutionHeightFraction=0.3] Optimization option. If between (0.0, 0.5], tiles at or above the screen space error for the reduced screen resolution of <code>progressiveResolutionHeightFraction*screenHeight</code> will be prioritized first. This can help get a quick layer of tiles down while full resolution tiles continue to load.
   * @param {Boolean} [options.foveatedScreenSpaceError=true] Optimization option. Prioritize loading tiles in the center of the screen by temporarily raising the screen space error for tiles around the edge of the screen. Screen space error returns to normal once all the tiles in the center of the screen as determined by the {@link Cesium3DTileset#foveatedConeSize} are loaded.
   * @param {Number} [options.foveatedConeSize=0.1] Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control the cone size that determines which tiles are deferred. Tiles that are inside this cone are loaded immediately. Tiles outside the cone are potentially deferred based on how far outside the cone they are and their screen space error. This is controlled by {@link Cesium3DTileset#foveatedInterpolationCallback} and {@link Cesium3DTileset#foveatedMinimumScreenSpaceErrorRelaxation}. Setting this to 0.0 means the cone will be the line formed by the camera position and its view direction. Setting this to 1.0 means the cone encompasses the entire field of view of the camera, disabling the effect.
   * @param {Number} [options.foveatedMinimumScreenSpaceErrorRelaxation=0.0] Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control the starting screen space error relaxation for tiles outside the foveated cone. The screen space error will be raised starting with tileset value up to {@link Cesium3DTileset#maximumScreenSpaceError} based on the provided {@link Cesium3DTileset#foveatedInterpolationCallback}.
   * @param {Cesium3DTileset.foveatedInterpolationCallback} [options.foveatedInterpolationCallback=Math.lerp] Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control how much to raise the screen space error for tiles outside the foveated cone, interpolating between {@link Cesium3DTileset#foveatedMinimumScreenSpaceErrorRelaxation} and {@link Cesium3DTileset#maximumScreenSpaceError}
   * @param {Number} [options.foveatedTimeDelay=0.2] Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control how long in seconds to wait after the camera stops moving before deferred tiles start loading in. This time delay prevents requesting tiles around the edges of the screen when the camera is moving. Setting this to 0.0 will immediately request all tiles in any given view.
   * @param {Boolean} [options.skipLevelOfDetail=false] Optimization option. Determines if level of detail skipping should be applied during the traversal.
   * @param {Number} [options.baseScreenSpaceError=1024] When <code>skipLevelOfDetail</code> is <code>true</code>, the screen space error that must be reached before skipping levels of detail.
   * @param {Number} [options.skipScreenSpaceErrorFactor=16] When <code>skipLevelOfDetail</code> is <code>true</code>, a multiplier defining the minimum screen space error to skip. Used in conjunction with <code>skipLevels</code> to determine which tiles to load.
   * @param {Number} [options.skipLevels=1] When <code>skipLevelOfDetail</code> is <code>true</code>, a constant defining the minimum number of levels to skip when loading tiles. When it is 0, no levels are skipped. Used in conjunction with <code>skipScreenSpaceErrorFactor</code> to determine which tiles to load.
   * @param {Boolean} [options.immediatelyLoadDesiredLevelOfDetail=false] When <code>skipLevelOfDetail</code> is <code>true</code>, only tiles that meet the maximum screen space error will ever be downloaded. Skipping factors are ignored and just the desired tiles are loaded.
   * @param {Boolean} [options.loadSiblings=false] When <code>skipLevelOfDetail</code> is <code>true</code>, determines whether siblings of visible tiles are always downloaded during traversal.
   * @param {ClippingPlaneCollection} [options.clippingPlanes] The {@link ClippingPlaneCollection} used to selectively disable rendering the tileset.
   * @param {ClassificationType} [options.classificationType] Determines whether terrain, 3D Tiles or both will be classified by this tileset. See {@link Cesium3DTileset#classificationType} for details about restrictions and limitations.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid determining the size and shape of the globe.
   * @param {Object} [options.pointCloudShading] Options for constructing a {@link PointCloudShading} object to control point attenuation based on geometric error and lighting.
   * @param {Cartesian2} [options.imageBasedLightingFactor=new Cartesian2(1.0, 1.0)] Scales the diffuse and specular image-based lighting from the earth, sky, atmosphere and star skybox.
   * @param {Cartesian3} [options.lightColor] The light color when shading models. When <code>undefined</code> the scene's light color is used instead.
   * @param {Number} [options.luminanceAtZenith=0.2] The sun's luminance at the zenith in kilo candela per meter squared to use for this model's procedural environment map.
   * @param {Cartesian3[]} [options.sphericalHarmonicCoefficients] The third order spherical harmonic coefficients used for the diffuse color of image-based lighting.
   * @param {String} [options.specularEnvironmentMaps] A URL to a KTX file that contains a cube map of the specular lighting and the convoluted specular mipmaps.
   * @param {Boolean} [options.backFaceCulling=true] Whether to cull back-facing geometry. When true, back face culling is determined by the glTF material's doubleSided property; when false, back face culling is disabled.
   * @param {String} [options.debugHeatmapTilePropertyName] The tile variable to colorize as a heatmap. All rendered tiles will be colorized relative to each other's specified variable value.
   * @param {Boolean} [options.debugFreezeFrame=false] For debugging only. Determines if only the tiles from last frame should be used for rendering.
   * @param {Boolean} [options.debugColorizeTiles=false] For debugging only. When true, assigns a random color to each tile.
   * @param {Boolean} [options.debugWireframe=false] For debugging only. When true, render's each tile's content as a wireframe.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. When true, renders the bounding volume for each tile.
   * @param {Boolean} [options.debugShowContentBoundingVolume=false] For debugging only. When true, renders the bounding volume for each tile's content.
   * @param {Boolean} [options.debugShowViewerRequestVolume=false] For debugging only. When true, renders the viewer request volume for each tile.
   * @param {Boolean} [options.debugShowGeometricError=false] For debugging only. When true, draws labels to indicate the geometric error of each tile.
   * @param {Boolean} [options.debugShowRenderingStatistics=false] For debugging only. When true, draws labels to indicate the number of commands, points, triangles and features for each tile.
   * @param {Boolean} [options.debugShowMemoryUsage=false] For debugging only. When true, draws labels to indicate the texture and geometry memory in megabytes used by each tile.
   * @param {Boolean} [options.debugShowUrl=false] For debugging only. When true, draws labels to indicate the url of each tile.
   *
   * @exception {DeveloperError} The tileset must be 3D Tiles version 0.0 or 1.0.
   *
   * @example
   * var tileset = scene.primitives.add(new Cesium.Cesium3DTileset({
   *      url : 'http://localhost:8002/tilesets/Seattle/tileset.json'
   * }));
   *
   * @example
   * // Common setting for the skipLevelOfDetail optimization
   * var tileset = scene.primitives.add(new Cesium.Cesium3DTileset({
   *      url : 'http://localhost:8002/tilesets/Seattle/tileset.json',
   *      skipLevelOfDetail : true,
   *      baseScreenSpaceError : 1024,
   *      skipScreenSpaceErrorFactor : 16,
   *      skipLevels : 1,
   *      immediatelyLoadDesiredLevelOfDetail : false,
   *      loadSiblings : false,
   *      cullWithChildrenBounds : true
   * }));
   *
   * @example
   * // Common settings for the dynamicScreenSpaceError optimization
   * var tileset = scene.primitives.add(new Cesium.Cesium3DTileset({
   *      url : 'http://localhost:8002/tilesets/Seattle/tileset.json',
   *      dynamicScreenSpaceError : true,
   *      dynamicScreenSpaceErrorDensity : 0.00278,
   *      dynamicScreenSpaceErrorFactor : 4.0,
   *      dynamicScreenSpaceErrorHeightFalloff : 0.25
   * }));
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification|3D Tiles specification}
   */
  function Cesium3DTileset(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.url", options.url);
    //>>includeEnd('debug');

    this._url = undefined;
    this._basePath = undefined;
    this._root = undefined;
    this._asset = undefined; // Metadata for the entire tileset
    this._properties = undefined; // Metadata for per-model/point/etc properties
    this._geometricError = undefined; // Geometric error when the tree is not rendered at all
    this._extensionsUsed = undefined;
    this._extensions = undefined;
    this._gltfUpAxis = undefined;
    this._cache = new Cesium3DTilesetCache();
    this._processingQueue = [];
    this._selectedTiles = [];
    this._emptyTiles = [];
    this._requestedTiles = [];
    this._selectedTilesToStyle = [];
    this._loadTimestamp = undefined;
    this._timeSinceLoad = 0.0;
    this._updatedVisibilityFrame = 0;
    this._updatedModelMatrixFrame = 0;
    this._modelMatrixChanged = false;
    this._previousModelMatrix = undefined;
    this._extras = undefined;
    this._credits = undefined;

    this._cullWithChildrenBounds = defaultValue(
      options.cullWithChildrenBounds,
      true
    );
    this._allTilesAdditive = true;

    this._hasMixedContent = false;

    this._stencilClearCommand = undefined;
    this._backfaceCommands = new ManagedArray();

    this._maximumScreenSpaceError = defaultValue(
      options.maximumScreenSpaceError,
      16
    );
    this._maximumMemoryUsage = defaultValue(options.maximumMemoryUsage, 512);

    this._styleEngine = new Cesium3DTileStyleEngine();

    this._modelMatrix = defined(options.modelMatrix)
      ? Matrix4.clone(options.modelMatrix)
      : Matrix4.clone(Matrix4.IDENTITY);

    this._statistics = new Cesium3DTilesetStatistics();
    this._statisticsLast = new Cesium3DTilesetStatistics();
    this._statisticsPerPass = new Array(Cesium3DTilePass$1.NUMBER_OF_PASSES);

    for (var i = 0; i < Cesium3DTilePass$1.NUMBER_OF_PASSES; ++i) {
      this._statisticsPerPass[i] = new Cesium3DTilesetStatistics();
    }

    this._requestedTilesInFlight = [];

    this._maximumPriority = {
      foveatedFactor: -Number.MAX_VALUE,
      depth: -Number.MAX_VALUE,
      distance: -Number.MAX_VALUE,
      reverseScreenSpaceError: -Number.MAX_VALUE,
    };
    this._minimumPriority = {
      foveatedFactor: Number.MAX_VALUE,
      depth: Number.MAX_VALUE,
      distance: Number.MAX_VALUE,
      reverseScreenSpaceError: Number.MAX_VALUE,
    };
    this._heatmap = new Cesium3DTilesetHeatmap(
      options.debugHeatmapTilePropertyName
    );

    /**
     * Optimization option. Don't request tiles that will likely be unused when they come back because of the camera's movement. This optimization only applies to stationary tilesets.
     *
     * @type {Boolean}
     * @default true
     */
    this.cullRequestsWhileMoving = defaultValue(
      options.cullRequestsWhileMoving,
      true
    );
    this._cullRequestsWhileMoving = false;

    /**
     * Optimization option. Multiplier used in culling requests while moving. Larger is more aggressive culling, smaller less aggressive culling.
     *
     * @type {Number}
     * @default 60.0
     */
    this.cullRequestsWhileMovingMultiplier = defaultValue(
      options.cullRequestsWhileMovingMultiplier,
      60.0
    );

    /**
     * Optimization option. If between (0.0, 0.5], tiles at or above the screen space error for the reduced screen resolution of <code>progressiveResolutionHeightFraction*screenHeight</code> will be prioritized first. This can help get a quick layer of tiles down while full resolution tiles continue to load.
     *
     * @type {Number}
     * @default 0.3
     */
    this.progressiveResolutionHeightFraction = CesiumMath.clamp(
      defaultValue(options.progressiveResolutionHeightFraction, 0.3),
      0.0,
      0.5
    );

    /**
     * Optimization option. Prefer loading of leaves first.
     *
     * @type {Boolean}
     * @default false
     */
    this.preferLeaves = defaultValue(options.preferLeaves, false);

    this._tilesLoaded = false;
    this._initialTilesLoaded = false;

    this._tileDebugLabels = undefined;

    this._readyPromise = when.defer();

    this._classificationType = options.classificationType;

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    this._initialClippingPlanesOriginMatrix = Matrix4.IDENTITY; // Computed from the tileset JSON.
    this._clippingPlanesOriginMatrix = undefined; // Combines the above with any run-time transforms.
    this._clippingPlanesOriginMatrixDirty = true;

    /**
     * Preload tiles when <code>tileset.show</code> is <code>false</code>. Loads tiles as if the tileset is visible but does not render them.
     *
     * @type {Boolean}
     * @default false
     */
    this.preloadWhenHidden = defaultValue(options.preloadWhenHidden, false);

    /**
     * Optimization option. Fetch tiles at the camera's flight destination while the camera is in flight.
     *
     * @type {Boolean}
     * @default true
     */
    this.preloadFlightDestinations = defaultValue(
      options.preloadFlightDestinations,
      true
    );
    this._pass = undefined; // Cesium3DTilePass

    /**
     * Optimization option. Whether the tileset should refine based on a dynamic screen space error. Tiles that are further
     * away will be rendered with lower detail than closer tiles. This improves performance by rendering fewer
     * tiles and making less requests, but may result in a slight drop in visual quality for tiles in the distance.
     * The algorithm is biased towards "street views" where the camera is close to the ground plane of the tileset and looking
     * at the horizon. In addition results are more accurate for tightly fitting bounding volumes like box and region.
     *
     * @type {Boolean}
     * @default false
     */
    this.dynamicScreenSpaceError = defaultValue(
      options.dynamicScreenSpaceError,
      false
    );

    /**
     * Optimization option. Prioritize loading tiles in the center of the screen by temporarily raising the
     * screen space error for tiles around the edge of the screen. Screen space error returns to normal once all
     * the tiles in the center of the screen as determined by the {@link Cesium3DTileset#foveatedConeSize} are loaded.
     *
     * @type {Boolean}
     * @default true
     */
    this.foveatedScreenSpaceError = defaultValue(
      options.foveatedScreenSpaceError,
      true
    );
    this._foveatedConeSize = defaultValue(options.foveatedConeSize, 0.1);
    this._foveatedMinimumScreenSpaceErrorRelaxation = defaultValue(
      options.foveatedMinimumScreenSpaceErrorRelaxation,
      0.0
    );

    /**
     * Gets or sets a callback to control how much to raise the screen space error for tiles outside the foveated cone,
     * interpolating between {@link Cesium3DTileset#foveatedMinimumScreenSpaceErrorRelaxation} and {@link Cesium3DTileset#maximumScreenSpaceError}.
     *
     * @type {Cesium3DTileset.foveatedInterpolationCallback}
     */
    this.foveatedInterpolationCallback = defaultValue(
      options.foveatedInterpolationCallback,
      CesiumMath.lerp
    );

    /**
     * Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control
     * how long in seconds to wait after the camera stops moving before deferred tiles start loading in.
     * This time delay prevents requesting tiles around the edges of the screen when the camera is moving.
     * Setting this to 0.0 will immediately request all tiles in any given view.
     *
     * @type {Number}
     * @default 0.2
     */
    this.foveatedTimeDelay = defaultValue(options.foveatedTimeDelay, 0.2);

    /**
     * A scalar that determines the density used to adjust the dynamic screen space error, similar to {@link Fog}. Increasing this
     * value has the effect of increasing the maximum screen space error for all tiles, but in a non-linear fashion.
     * The error starts at 0.0 and increases exponentially until a midpoint is reached, and then approaches 1.0 asymptotically.
     * This has the effect of keeping high detail in the closer tiles and lower detail in the further tiles, with all tiles
     * beyond a certain distance all roughly having an error of 1.0.
     * <p>
     * The dynamic error is in the range [0.0, 1.0) and is multiplied by <code>dynamicScreenSpaceErrorFactor</code> to produce the
     * final dynamic error. This dynamic error is then subtracted from the tile's actual screen space error.
     * </p>
     * <p>
     * Increasing <code>dynamicScreenSpaceErrorDensity</code> has the effect of moving the error midpoint closer to the camera.
     * It is analogous to moving fog closer to the camera.
     * </p>
     *
     * @type {Number}
     * @default 0.00278
     */
    this.dynamicScreenSpaceErrorDensity = 0.00278;

    /**
     * A factor used to increase the screen space error of tiles for dynamic screen space error. As this value increases less tiles
     * are requested for rendering and tiles in the distance will have lower detail. If set to zero, the feature will be disabled.
     *
     * @type {Number}
     * @default 4.0
     */
    this.dynamicScreenSpaceErrorFactor = 4.0;

    /**
     * A ratio of the tileset's height at which the density starts to falloff. If the camera is below this height the
     * full computed density is applied, otherwise the density falls off. This has the effect of higher density at
     * street level views.
     * <p>
     * Valid values are between 0.0 and 1.0.
     * </p>
     *
     * @type {Number}
     * @default 0.25
     */
    this.dynamicScreenSpaceErrorHeightFalloff = 0.25;

    this._dynamicScreenSpaceErrorComputedDensity = 0.0; // Updated based on the camera position and direction

    /**
     * Determines whether the tileset casts or receives shadows from light sources.
     * <p>
     * Enabling shadows has a performance impact. A tileset that casts shadows must be rendered twice, once from the camera and again from the light's point of view.
     * </p>
     * <p>
     * Shadows are rendered only when {@link Viewer#shadows} is <code>true</code>.
     * </p>
     *
     * @type {ShadowMode}
     * @default ShadowMode.ENABLED
     */
    this.shadows = defaultValue(options.shadows, ShadowMode$1.ENABLED);

    /**
     * Determines if the tileset will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * Defines how per-feature colors set from the Cesium API or declarative styling blend with the source colors from
     * the original feature, e.g. glTF material or per-point color in the tile.
     *
     * @type {Cesium3DTileColorBlendMode}
     * @default Cesium3DTileColorBlendMode.HIGHLIGHT
     */
    this.colorBlendMode = Cesium3DTileColorBlendMode$1.HIGHLIGHT;

    /**
     * Defines the value used to linearly interpolate between the source color and feature color when the {@link Cesium3DTileset#colorBlendMode} is <code>MIX</code>.
     * A value of 0.0 results in the source color while a value of 1.0 results in the feature color, with any value in-between
     * resulting in a mix of the source color and feature color.
     *
     * @type {Number}
     * @default 0.5
     */
    this.colorBlendAmount = 0.5;

    /**
     * Options for controlling point size based on geometric error and eye dome lighting.
     * @type {PointCloudShading}
     */
    this.pointCloudShading = new PointCloudShading(options.pointCloudShading);

    this._pointCloudEyeDomeLighting = new PointCloudEyeDomeLighting();

    /**
     * The event fired to indicate progress of loading new tiles.  This event is fired when a new tile
     * is requested, when a requested tile is finished downloading, and when a downloaded tile has been
     * processed and is ready to render.
     * <p>
     * The number of pending tile requests, <code>numberOfPendingRequests</code>, and number of tiles
     * processing, <code>numberOfTilesProcessing</code> are passed to the event listener.
     * </p>
     * <p>
     * This event is fired at the end of the frame after the scene is rendered.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.loadProgress.addEventListener(function(numberOfPendingRequests, numberOfTilesProcessing) {
     *     if ((numberOfPendingRequests === 0) && (numberOfTilesProcessing === 0)) {
     *         console.log('Stopped loading');
     *         return;
     *     }
     *
     *     console.log('Loading: requests: ' + numberOfPendingRequests + ', processing: ' + numberOfTilesProcessing);
     * });
     */
    this.loadProgress = new Event();

    /**
     * The event fired to indicate that all tiles that meet the screen space error this frame are loaded. The tileset
     * is completely loaded for this view.
     * <p>
     * This event is fired at the end of the frame after the scene is rendered.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.allTilesLoaded.addEventListener(function() {
     *     console.log('All tiles are loaded');
     * });
     *
     * @see Cesium3DTileset#tilesLoaded
     */
    this.allTilesLoaded = new Event();

    /**
     * The event fired to indicate that all tiles that meet the screen space error this frame are loaded. This event
     * is fired once when all tiles in the initial view are loaded.
     * <p>
     * This event is fired at the end of the frame after the scene is rendered.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.initialTilesLoaded.addEventListener(function() {
     *     console.log('Initial tiles are loaded');
     * });
     *
     * @see Cesium3DTileset#allTilesLoaded
     */
    this.initialTilesLoaded = new Event();

    /**
     * The event fired to indicate that a tile's content was loaded.
     * <p>
     * The loaded {@link Cesium3DTile} is passed to the event listener.
     * </p>
     * <p>
     * This event is fired during the tileset traversal while the frame is being rendered
     * so that updates to the tile take effect in the same frame.  Do not create or modify
     * Cesium entities or primitives during the event listener.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.tileLoad.addEventListener(function(tile) {
     *     console.log('A tile was loaded.');
     * });
     */
    this.tileLoad = new Event();

    /**
     * The event fired to indicate that a tile's content was unloaded.
     * <p>
     * The unloaded {@link Cesium3DTile} is passed to the event listener.
     * </p>
     * <p>
     * This event is fired immediately before the tile's content is unloaded while the frame is being
     * rendered so that the event listener has access to the tile's content.  Do not create
     * or modify Cesium entities or primitives during the event listener.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.tileUnload.addEventListener(function(tile) {
     *     console.log('A tile was unloaded from the cache.');
     * });
     *
     * @see Cesium3DTileset#maximumMemoryUsage
     * @see Cesium3DTileset#trimLoadedTiles
     */
    this.tileUnload = new Event();

    /**
     * The event fired to indicate that a tile's content failed to load.
     * <p>
     * If there are no event listeners, error messages will be logged to the console.
     * </p>
     * <p>
     * The error object passed to the listener contains two properties:
     * <ul>
     * <li><code>url</code>: the url of the failed tile.</li>
     * <li><code>message</code>: the error message.</li>
     * </ul>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.tileFailed.addEventListener(function(error) {
     *     console.log('An error occurred loading tile: ' + error.url);
     *     console.log('Error: ' + error.message);
     * });
     */
    this.tileFailed = new Event();

    /**
     * This event fires once for each visible tile in a frame.  This can be used to manually
     * style a tileset.
     * <p>
     * The visible {@link Cesium3DTile} is passed to the event listener.
     * </p>
     * <p>
     * This event is fired during the tileset traversal while the frame is being rendered
     * so that updates to the tile take effect in the same frame.  Do not create or modify
     * Cesium entities or primitives during the event listener.
     * </p>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * tileset.tileVisible.addEventListener(function(tile) {
     *     if (tile.content instanceof Cesium.Batched3DModel3DTileContent) {
     *         console.log('A Batched 3D Model tile is visible.');
     *     }
     * });
     *
     * @example
     * // Apply a red style and then manually set random colors for every other feature when the tile becomes visible.
     * tileset.style = new Cesium.Cesium3DTileStyle({
     *     color : 'color("red")'
     * });
     * tileset.tileVisible.addEventListener(function(tile) {
     *     var content = tile.content;
     *     var featuresLength = content.featuresLength;
     *     for (var i = 0; i < featuresLength; i+=2) {
     *         content.getFeature(i).color = Cesium.Color.fromRandom();
     *     }
     * });
     */
    this.tileVisible = new Event();

    /**
     * Optimization option. Determines if level of detail skipping should be applied during the traversal.
     * <p>
     * The common strategy for replacement-refinement traversal is to store all levels of the tree in memory and require
     * all children to be loaded before the parent can refine. With this optimization levels of the tree can be skipped
     * entirely and children can be rendered alongside their parents. The tileset requires significantly less memory when
     * using this optimization.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.skipLevelOfDetail = defaultValue(options.skipLevelOfDetail, false);
    this._skipLevelOfDetail = this.skipLevelOfDetail;
    this._disableSkipLevelOfDetail = false;

    /**
     * The screen space error that must be reached before skipping levels of detail.
     * <p>
     * Only used when {@link Cesium3DTileset#skipLevelOfDetail} is <code>true</code>.
     * </p>
     *
     * @type {Number}
     * @default 1024
     */
    this.baseScreenSpaceError = defaultValue(options.baseScreenSpaceError, 1024);

    /**
     * Multiplier defining the minimum screen space error to skip.
     * For example, if a tile has screen space error of 100, no tiles will be loaded unless they
     * are leaves or have a screen space error <code><= 100 / skipScreenSpaceErrorFactor</code>.
     * <p>
     * Only used when {@link Cesium3DTileset#skipLevelOfDetail} is <code>true</code>.
     * </p>
     *
     * @type {Number}
     * @default 16
     */
    this.skipScreenSpaceErrorFactor = defaultValue(
      options.skipScreenSpaceErrorFactor,
      16
    );

    /**
     * Constant defining the minimum number of levels to skip when loading tiles. When it is 0, no levels are skipped.
     * For example, if a tile is level 1, no tiles will be loaded unless they are at level greater than 2.
     * <p>
     * Only used when {@link Cesium3DTileset#skipLevelOfDetail} is <code>true</code>.
     * </p>
     *
     * @type {Number}
     * @default 1
     */
    this.skipLevels = defaultValue(options.skipLevels, 1);

    /**
     * When true, only tiles that meet the maximum screen space error will ever be downloaded.
     * Skipping factors are ignored and just the desired tiles are loaded.
     * <p>
     * Only used when {@link Cesium3DTileset#skipLevelOfDetail} is <code>true</code>.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.immediatelyLoadDesiredLevelOfDetail = defaultValue(
      options.immediatelyLoadDesiredLevelOfDetail,
      false
    );

    /**
     * Determines whether siblings of visible tiles are always downloaded during traversal.
     * This may be useful for ensuring that tiles are already available when the viewer turns left/right.
     * <p>
     * Only used when {@link Cesium3DTileset#skipLevelOfDetail} is <code>true</code>.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.loadSiblings = defaultValue(options.loadSiblings, false);

    this._clippingPlanes = undefined;
    this.clippingPlanes = options.clippingPlanes;

    this._imageBasedLightingFactor = new Cartesian2(1.0, 1.0);
    Cartesian2.clone(
      options.imageBasedLightingFactor,
      this._imageBasedLightingFactor
    );

    /**
     * The light color when shading models. When <code>undefined</code> the scene's light color is used instead.
     * <p>
     * For example, disabling additional light sources by setting <code>model.imageBasedLightingFactor = new Cartesian2(0.0, 0.0)</code> will make the
     * model much darker. Here, increasing the intensity of the light source will make the model brighter.
     * </p>
     *
     * @type {Cartesian3}
     * @default undefined
     */
    this.lightColor = options.lightColor;

    /**
     * The sun's luminance at the zenith in kilo candela per meter squared to use for this model's procedural environment map.
     * This is used when {@link Cesium3DTileset#specularEnvironmentMaps} and {@link Cesium3DTileset#sphericalHarmonicCoefficients} are not defined.
     *
     * @type Number
     *
     * @default 0.2
     *
     */
    this.luminanceAtZenith = defaultValue(options.luminanceAtZenith, 0.2);

    /**
     * The third order spherical harmonic coefficients used for the diffuse color of image-based lighting. When <code>undefined</code>, a diffuse irradiance
     * computed from the atmosphere color is used.
     * <p>
     * There are nine <code>Cartesian3</code> coefficients.
     * The order of the coefficients is: L<sub>00</sub>, L<sub>1-1</sub>, L<sub>10</sub>, L<sub>11</sub>, L<sub>2-2</sub>, L<sub>2-1</sub>, L<sub>20</sub>, L<sub>21</sub>, L<sub>22</sub>
     * </p>
     *
     * These values can be obtained by preprocessing the environment map using the <code>cmgen</code> tool of
     * {@link https://github.com/google/filament/releases|Google's Filament project}. This will also generate a KTX file that can be
     * supplied to {@link Cesium3DTileset#specularEnvironmentMaps}.
     *
     * @type {Cartesian3[]}
     * @demo {@link https://sandcastle.cesium.com/index.html?src=Image-Based Lighting.html|Sandcastle Image Based Lighting Demo}
     * @see {@link https://graphics.stanford.edu/papers/envmap/envmap.pdf|An Efficient Representation for Irradiance Environment Maps}
     */
    this.sphericalHarmonicCoefficients = options.sphericalHarmonicCoefficients;

    /**
     * A URL to a KTX file that contains a cube map of the specular lighting and the convoluted specular mipmaps.
     *
     * @demo {@link https://sandcastle.cesium.com/index.html?src=Image-Based Lighting.html|Sandcastle Image Based Lighting Demo}
     * @type {String}
     * @see Cesium3DTileset#sphericalHarmonicCoefficients
     */
    this.specularEnvironmentMaps = options.specularEnvironmentMaps;

    /**
     * Whether to cull back-facing geometry. When true, back face culling is determined
     * by the glTF material's doubleSided property; when false, back face culling is disabled.
     *
     * @type {Boolean}
     * @default true
     */
    this.backFaceCulling = defaultValue(options.backFaceCulling, true);

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * Determines if only the tiles from last frame should be used for rendering.  This
     * effectively "freezes" the tileset to the previous frame so it is possible to zoom
     * out and see what was rendered.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugFreezeFrame = defaultValue(options.debugFreezeFrame, false);

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, assigns a random color to each tile.  This is useful for visualizing
     * what features belong to what tiles, especially with additive refinement where features
     * from parent tiles may be interleaved with features from child tiles.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugColorizeTiles = defaultValue(options.debugColorizeTiles, false);

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, renders each tile's content as a wireframe.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugWireframe = defaultValue(options.debugWireframe, false);

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, renders the bounding volume for each visible tile.  The bounding volume is
     * white if the tile has a content bounding volume or is empty; otherwise, it is red.  Tiles that don't meet the
     * screen space error and are still refining to their descendants are yellow.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, renders the bounding volume for each visible tile's content. The bounding volume is
     * blue if the tile has a content bounding volume; otherwise it is red.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowContentBoundingVolume = defaultValue(
      options.debugShowContentBoundingVolume,
      false
    );

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, renders the viewer request volume for each tile.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowViewerRequestVolume = defaultValue(
      options.debugShowViewerRequestVolume,
      false
    );

    this._tileDebugLabels = undefined;
    this.debugPickedTileLabelOnly = false;
    this.debugPickedTile = undefined;
    this.debugPickPosition = undefined;

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, draws labels to indicate the geometric error of each tile.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowGeometricError = defaultValue(
      options.debugShowGeometricError,
      false
    );

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, draws labels to indicate the number of commands, points, triangles and features of each tile.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowRenderingStatistics = defaultValue(
      options.debugShowRenderingStatistics,
      false
    );

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, draws labels to indicate the geometry and texture memory usage of each tile.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowMemoryUsage = defaultValue(options.debugShowMemoryUsage, false);

    /**
     * This property is for debugging only; it is not optimized for production use.
     * <p>
     * When true, draws labels to indicate the url of each tile.
     * </p>
     *
     * @type {Boolean}
     * @default false
     */
    this.debugShowUrl = defaultValue(options.debugShowUrl, false);

    var that = this;
    var resource;
    when(options.url)
      .then(function (url) {
        var basePath;
        resource = Resource.createIfNeeded(url);

        // ion resources have a credits property we can use for additional attribution.
        that._credits = resource.credits;

        if (resource.extension === "json") {
          basePath = resource.getBaseUri(true);
        } else if (resource.isDataUri) {
          basePath = "";
        }

        that._url = resource.url;
        that._basePath = basePath;

        return Cesium3DTileset.loadJson(resource);
      })
      .then(function (tilesetJson) {
        that._root = that.loadTileset(resource, tilesetJson);
        var gltfUpAxis = defined(tilesetJson.asset.gltfUpAxis)
          ? Axis$1.fromName(tilesetJson.asset.gltfUpAxis)
          : Axis$1.Y;
        var asset = tilesetJson.asset;
        that._asset = asset;
        that._properties = tilesetJson.properties;
        that._geometricError = tilesetJson.geometricError;
        that._extensionsUsed = tilesetJson.extensionsUsed;
        that._extensions = tilesetJson.extensions;
        that._gltfUpAxis = gltfUpAxis;
        that._extras = tilesetJson.extras;

        var extras = asset.extras;
        if (
          defined(extras) &&
          defined(extras.cesium) &&
          defined(extras.cesium.credits)
        ) {
          var extraCredits = extras.cesium.credits;
          var credits = that._credits;
          if (!defined(credits)) {
            credits = [];
            that._credits = credits;
          }
          for (var i = 0; i < extraCredits.length; ++i) {
            var credit = extraCredits[i];
            credits.push(new Credit(credit.html, credit.showOnScreen));
          }
        }

        // Save the original, untransformed bounding volume position so we can apply
        // the tile transform and model matrix at run time
        var boundingVolume = that._root.createBoundingVolume(
          tilesetJson.root.boundingVolume,
          Matrix4.IDENTITY
        );
        var clippingPlanesOrigin = boundingVolume.boundingSphere.center;
        // If this origin is above the surface of the earth
        // we want to apply an ENU orientation as our best guess of orientation.
        // Otherwise, we assume it gets its position/orientation completely from the
        // root tile transform and the tileset's model matrix
        var originCartographic = that._ellipsoid.cartesianToCartographic(
          clippingPlanesOrigin
        );
        if (
          defined(originCartographic) &&
          originCartographic.height >
            ApproximateTerrainHeights._defaultMinTerrainHeight
        ) {
          that._initialClippingPlanesOriginMatrix = Transforms.eastNorthUpToFixedFrame(
            clippingPlanesOrigin
          );
        }
        that._clippingPlanesOriginMatrix = Matrix4.clone(
          that._initialClippingPlanesOriginMatrix
        );
        that._readyPromise.resolve(that);
      })
      .otherwise(function (error) {
        that._readyPromise.reject(error);
      });
  }

  Object.defineProperties(Cesium3DTileset.prototype, {
    /**
     * NOTE: This getter exists so that `Picking.js` can differentiate between
     *       PrimitiveCollection and Cesium3DTileset objects without inflating
     *       the size of the module via `instanceof Cesium3DTileset`
     * @private
     */
    isCesium3DTileset: {
      get: function () {
        return true;
      },
    },

    /**
     * Gets the tileset's asset object property, which contains metadata about the tileset.
     * <p>
     * See the {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification#reference-asset|asset schema reference}
     * in the 3D Tiles spec for the full set of properties.
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @exception {DeveloperError} The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true.
     */
    asset: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._asset;
      },
    },

    /**
     * Gets the tileset's extensions object property.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @exception {DeveloperError} The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true.
     */
    extensions: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._extensions;
      },
    },

    /**
     * The {@link ClippingPlaneCollection} used to selectively disable rendering the tileset.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {ClippingPlaneCollection}
     */
    clippingPlanes: {
      get: function () {
        return this._clippingPlanes;
      },
      set: function (value) {
        ClippingPlaneCollection.setOwner(value, this, "_clippingPlanes");
      },
    },

    /**
     * Gets the tileset's properties dictionary object, which contains metadata about per-feature properties.
     * <p>
     * See the {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification#reference-properties|properties schema reference}
     * in the 3D Tiles spec for the full set of properties.
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @exception {DeveloperError} The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true.
     *
     * @example
     * console.log('Maximum building height: ' + tileset.properties.height.maximum);
     * console.log('Minimum building height: ' + tileset.properties.height.minimum);
     *
     * @see Cesium3DTileFeature#getProperty
     * @see Cesium3DTileFeature#setProperty
     */
    properties: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._properties;
      },
    },

    /**
     * When <code>true</code>, the tileset's root tile is loaded and the tileset is ready to render.
     * This is set to <code>true</code> right before {@link Cesium3DTileset#readyPromise} is resolved.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    ready: {
      get: function () {
        return defined(this._root);
      },
    },

    /**
     * Gets the promise that will be resolved when the tileset's root tile is loaded and the tileset is ready to render.
     * <p>
     * This promise is resolved at the end of the frame before the first frame the tileset is rendered in.
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Promise.<Cesium3DTileset>}
     * @readonly
     *
     * @example
     * tileset.readyPromise.then(function(tileset) {
     *     // tile.properties is not defined until readyPromise resolves.
     *     var properties = tileset.properties;
     *     if (Cesium.defined(properties)) {
     *         for (var name in properties) {
     *             console.log(properties[name]);
     *         }
     *     }
     * });
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * When <code>true</code>, all tiles that meet the screen space error this frame are loaded. The tileset is
     * completely loaded for this view.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     *
     * @see Cesium3DTileset#allTilesLoaded
     */
    tilesLoaded: {
      get: function () {
        return this._tilesLoaded;
      },
    },

    /**
     * The url to a tileset JSON file.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._url;
      },
    },

    /**
     * The base path that non-absolute paths in tileset JSON file are relative to.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {String}
     * @readonly
     * @deprecated
     */
    basePath: {
      get: function () {
        deprecationWarning(
          "Cesium3DTileset.basePath",
          "Cesium3DTileset.basePath has been deprecated. All tiles are relative to the url of the tileset JSON file that contains them. Use the url property instead."
        );
        return this._basePath;
      },
    },

    /**
     * The style, defined using the
     * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language},
     * applied to each feature in the tileset.
     * <p>
     * Assign <code>undefined</code> to remove the style, which will restore the visual
     * appearance of the tileset to its default when no style was applied.
     * </p>
     * <p>
     * The style is applied to a tile before the {@link Cesium3DTileset#tileVisible}
     * event is raised, so code in <code>tileVisible</code> can manually set a feature's
     * properties (e.g. color and show) after the style is applied. When
     * a new style is assigned any manually set properties are overwritten.
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Cesium3DTileStyle|undefined}
     *
     * @default undefined
     *
     * @example
     * tileset.style = new Cesium.Cesium3DTileStyle({
     *    color : {
     *        conditions : [
     *            ['${Height} >= 100', 'color("purple", 0.5)'],
     *            ['${Height} >= 50', 'color("red")'],
     *            ['true', 'color("blue")']
     *        ]
     *    },
     *    show : '${Height} > 0',
     *    meta : {
     *        description : '"Building id ${id} has height ${Height}."'
     *    }
     * });
     *
     * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
     */
    style: {
      get: function () {
        return this._styleEngine.style;
      },
      set: function (value) {
        this._styleEngine.style = value;
      },
    },

    /**
     * The maximum screen space error used to drive level of detail refinement.  This value helps determine when a tile
     * refines to its descendants, and therefore plays a major role in balancing performance with visual quality.
     * <p>
     * A tile's screen space error is roughly equivalent to the number of pixels wide that would be drawn if a sphere with a
     * radius equal to the tile's <b>geometric error</b> were rendered at the tile's position. If this value exceeds
     * <code>maximumScreenSpaceError</code> the tile refines to its descendants.
     * </p>
     * <p>
     * Depending on the tileset, <code>maximumScreenSpaceError</code> may need to be tweaked to achieve the right balance.
     * Higher values provide better performance but lower visual quality.
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Number}
     * @default 16
     *
     * @exception {DeveloperError} <code>maximumScreenSpaceError</code> must be greater than or equal to zero.
     */
    maximumScreenSpaceError: {
      get: function () {
        return this._maximumScreenSpaceError;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals(
          "maximumScreenSpaceError",
          value,
          0
        );
        //>>includeEnd('debug');

        this._maximumScreenSpaceError = value;
      },
    },

    /**
     * The maximum amount of GPU memory (in MB) that may be used to cache tiles. This value is estimated from
     * geometry, textures, and batch table textures of loaded tiles. For point clouds, this value also
     * includes per-point metadata.
     * <p>
     * Tiles not in view are unloaded to enforce this.
     * </p>
     * <p>
     * If decreasing this value results in unloading tiles, the tiles are unloaded the next frame.
     * </p>
     * <p>
     * If tiles sized more than <code>maximumMemoryUsage</code> are needed
     * to meet the desired screen space error, determined by {@link Cesium3DTileset#maximumScreenSpaceError},
     * for the current view, then the memory usage of the tiles loaded will exceed
     * <code>maximumMemoryUsage</code>.  For example, if the maximum is 256 MB, but
     * 300 MB of tiles are needed to meet the screen space error, then 300 MB of tiles may be loaded.  When
     * these tiles go out of view, they will be unloaded.
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Number}
     * @default 512
     *
     * @exception {DeveloperError} <code>maximumMemoryUsage</code> must be greater than or equal to zero.
     * @see Cesium3DTileset#totalMemoryUsageInBytes
     */
    maximumMemoryUsage: {
      get: function () {
        return this._maximumMemoryUsage;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0);
        //>>includeEnd('debug');

        this._maximumMemoryUsage = value;
      },
    },

    /**
     * The root tile.
     *
     * @memberOf Cesium3DTileset.prototype
     *
     * @type {Cesium3DTile}
     * @readonly
     *
     * @exception {DeveloperError} The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true.
     */
    root: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._root;
      },
    },

    /**
     * The tileset's bounding sphere.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     *
     * @exception {DeveloperError} The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true.
     *
     * @example
     * var tileset = viewer.scene.primitives.add(new Cesium.Cesium3DTileset({
     *     url : 'http://localhost:8002/tilesets/Seattle/tileset.json'
     * }));
     *
     * tileset.readyPromise.then(function(tileset) {
     *     // Set the camera to view the newly added tileset
     *     viewer.camera.viewBoundingSphere(tileset.boundingSphere, new Cesium.HeadingPitchRange(0, -0.5, 0));
     * });
     */
    boundingSphere: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true."
          );
        }
        //>>includeEnd('debug');

        this._root.updateTransform(this._modelMatrix);
        return this._root.boundingSphere;
      },
    },

    /**
     * A 4x4 transformation matrix that transforms the entire tileset.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Matrix4}
     * @default Matrix4.IDENTITY
     *
     * @example
     * // Adjust a tileset's height from the globe's surface.
     * var heightOffset = 20.0;
     * var boundingSphere = tileset.boundingSphere;
     * var cartographic = Cesium.Cartographic.fromCartesian(boundingSphere.center);
     * var surface = Cesium.Cartesian3.fromRadians(cartographic.longitude, cartographic.latitude, 0.0);
     * var offset = Cesium.Cartesian3.fromRadians(cartographic.longitude, cartographic.latitude, heightOffset);
     * var translation = Cesium.Cartesian3.subtract(offset, surface, new Cesium.Cartesian3());
     * tileset.modelMatrix = Cesium.Matrix4.fromTranslation(translation);
     */
    modelMatrix: {
      get: function () {
        return this._modelMatrix;
      },
      set: function (value) {
        this._modelMatrix = Matrix4.clone(value, this._modelMatrix);
      },
    },

    /**
     * Returns the time, in milliseconds, since the tileset was loaded and first updated.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Number}
     * @readonly
     */
    timeSinceLoad: {
      get: function () {
        return this._timeSinceLoad;
      },
    },

    /**
     * The total amount of GPU memory in bytes used by the tileset. This value is estimated from
     * geometry, texture, and batch table textures of loaded tiles. For point clouds, this value also
     * includes per-point metadata.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @see Cesium3DTileset#maximumMemoryUsage
     */
    totalMemoryUsageInBytes: {
      get: function () {
        var statistics = this._statistics;
        return (
          statistics.texturesByteLength +
          statistics.geometryByteLength +
          statistics.batchTableByteLength
        );
      },
    },

    /**
     * @private
     */
    clippingPlanesOriginMatrix: {
      get: function () {
        if (!defined(this._clippingPlanesOriginMatrix)) {
          return Matrix4.IDENTITY;
        }

        if (this._clippingPlanesOriginMatrixDirty) {
          Matrix4.multiply(
            this.root.computedTransform,
            this._initialClippingPlanesOriginMatrix,
            this._clippingPlanesOriginMatrix
          );
          this._clippingPlanesOriginMatrixDirty = false;
        }

        return this._clippingPlanesOriginMatrix;
      },
    },

    /**
     * @private
     */
    styleEngine: {
      get: function () {
        return this._styleEngine;
      },
    },

    /**
     * @private
     */
    statistics: {
      get: function () {
        return this._statistics;
      },
    },

    /**
     * Determines whether terrain, 3D Tiles or both will be classified by this tileset.
     * <p>
     * This option is only applied to tilesets containing batched 3D models, geometry data, or vector data. Even when undefined, vector data and geometry data
     * must render as classifications and will default to rendering on both terrain and other 3D Tiles tilesets.
     * </p>
     * <p>
     * When enabled for batched 3D model tilesets, there are a few requirements/limitations on the glTF:
     * <ul>
     *     <li>POSITION and _BATCHID semantics are required.</li>
     *     <li>All indices with the same batch id must occupy contiguous sections of the index buffer.</li>
     *     <li>All shaders and techniques are ignored. The generated shader simply multiplies the position by the model-view-projection matrix.</li>
     *     <li>The only supported extensions are CESIUM_RTC and WEB3D_quantized_attributes.</li>
     *     <li>Only one node is supported.</li>
     *     <li>Only one mesh per node is supported.</li>
     *     <li>Only one primitive per mesh is supported.</li>
     * </ul>
     * </p>
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {ClassificationType}
     * @default undefined
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     * @readonly
     */
    classificationType: {
      get: function () {
        return this._classificationType;
      },
    },

    /**
     * Gets an ellipsoid describing the shape of the globe.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },

    /**
     * Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control the cone size that determines which tiles are deferred.
     * Tiles that are inside this cone are loaded immediately. Tiles outside the cone are potentially deferred based on how far outside the cone they are and {@link Cesium3DTileset#foveatedInterpolationCallback} and {@link Cesium3DTileset#foveatedMinimumScreenSpaceErrorRelaxation}.
     * Setting this to 0.0 means the cone will be the line formed by the camera position and its view direction. Setting this to 1.0 means the cone encompasses the entire field of view of the camera, essentially disabling the effect.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Number}
     * @default 0.3
     */
    foveatedConeSize: {
      get: function () {
        return this._foveatedConeSize;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("foveatedConeSize", value, 0.0);
        Check.typeOf.number.lessThanOrEquals("foveatedConeSize", value, 1.0);
        //>>includeEnd('debug');

        this._foveatedConeSize = value;
      },
    },

    /**
     * Optimization option. Used when {@link Cesium3DTileset#foveatedScreenSpaceError} is true to control the starting screen space error relaxation for tiles outside the foveated cone.
     * The screen space error will be raised starting with this value up to {@link Cesium3DTileset#maximumScreenSpaceError} based on the provided {@link Cesium3DTileset#foveatedInterpolationCallback}.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Number}
     * @default 0.0
     */
    foveatedMinimumScreenSpaceErrorRelaxation: {
      get: function () {
        return this._foveatedMinimumScreenSpaceErrorRelaxation;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals(
          "foveatedMinimumScreenSpaceErrorRelaxation",
          value,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "foveatedMinimumScreenSpaceErrorRelaxation",
          value,
          this.maximumScreenSpaceError
        );
        //>>includeEnd('debug');

        this._foveatedMinimumScreenSpaceErrorRelaxation = value;
      },
    },

    /**
     * Returns the <code>extras</code> property at the top-level of the tileset JSON, which contains application specific metadata.
     * Returns <code>undefined</code> if <code>extras</code> does not exist.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @exception {DeveloperError} The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true.
     *
     * @type {*}
     * @readonly
     *
     * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification#specifying-extensions-and-application-specific-extras|Extras in the 3D Tiles specification.}
     */
    extras: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "The tileset is not loaded.  Use Cesium3DTileset.readyPromise or wait for Cesium3DTileset.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._extras;
      },
    },

    /**
     * Cesium adds lighting from the earth, sky, atmosphere, and star skybox. This cartesian is used to scale the final
     * diffuse and specular lighting contribution from those sources to the final color. A value of 0.0 will disable those light sources.
     *
     * @memberof Cesium3DTileset.prototype
     *
     * @type {Cartesian2}
     * @default Cartesian2(1.0, 1.0)
     */
    imageBasedLightingFactor: {
      get: function () {
        return this._imageBasedLightingFactor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.object("imageBasedLightingFactor", value);
        Check.typeOf.number.greaterThanOrEquals(
          "imageBasedLightingFactor.x",
          value.x,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "imageBasedLightingFactor.x",
          value.x,
          1.0
        );
        Check.typeOf.number.greaterThanOrEquals(
          "imageBasedLightingFactor.y",
          value.y,
          0.0
        );
        Check.typeOf.number.lessThanOrEquals(
          "imageBasedLightingFactor.y",
          value.y,
          1.0
        );
        //>>includeEnd('debug');
        Cartesian2.clone(value, this._imageBasedLightingFactor);
      },
    },
  });

  /**
   * Provides a hook to override the method used to request the tileset json
   * useful when fetching tilesets from remote servers
   * @param {Resource|String} tilesetUrl The url of the json file to be fetched
   * @returns {Promise.<Object>} A promise that resolves with the fetched json data
   */
  Cesium3DTileset.loadJson = function (tilesetUrl) {
    var resource = Resource.createIfNeeded(tilesetUrl);
    return resource.fetchJson();
  };

  /**
   * Marks the tileset's {@link Cesium3DTileset#style} as dirty, which forces all
   * features to re-evaluate the style in the next frame each is visible.
   */
  Cesium3DTileset.prototype.makeStyleDirty = function () {
    this._styleEngine.makeDirty();
  };

  /**
   * Loads the main tileset JSON file or a tileset JSON file referenced from a tile.
   *
   * @private
   */
  Cesium3DTileset.prototype.loadTileset = function (
    resource,
    tilesetJson,
    parentTile
  ) {
    var asset = tilesetJson.asset;
    if (!defined(asset)) {
      throw new RuntimeError("Tileset must have an asset property.");
    }
    if (asset.version !== "0.0" && asset.version !== "1.0") {
      throw new RuntimeError("The tileset must be 3D Tiles version 0.0 or 1.0.");
    }

    var statistics = this._statistics;

    var tilesetVersion = asset.tilesetVersion;
    if (defined(tilesetVersion)) {
      // Append the tileset version to the resource
      this._basePath += "?v=" + tilesetVersion;
      resource.setQueryParameters({ v: tilesetVersion });
    }

    // A tileset JSON file referenced from a tile may exist in a different directory than the root tileset.
    // Get the basePath relative to the external tileset.
    var rootTile = new Cesium3DTile(this, resource, tilesetJson.root, parentTile);

    // If there is a parentTile, add the root of the currently loading tileset
    // to parentTile's children, and update its _depth.
    if (defined(parentTile)) {
      parentTile.children.push(rootTile);
      rootTile._depth = parentTile._depth + 1;
    }

    var stack = [];
    stack.push(rootTile);

    while (stack.length > 0) {
      var tile = stack.pop();
      ++statistics.numberOfTilesTotal;
      this._allTilesAdditive =
        this._allTilesAdditive && tile.refine === Cesium3DTileRefine$1.ADD;
      var children = tile._header.children;
      if (defined(children)) {
        var length = children.length;
        for (var i = 0; i < length; ++i) {
          var childHeader = children[i];
          var childTile = new Cesium3DTile(this, resource, childHeader, tile);
          tile.children.push(childTile);
          childTile._depth = tile._depth + 1;
          stack.push(childTile);
        }
      }

      if (this._cullWithChildrenBounds) {
        Cesium3DTileOptimizations.checkChildrenWithinParent(tile);
      }
    }

    return rootTile;
  };

  var scratchPositionNormal = new Cartesian3();
  var scratchCartographic$7 = new Cartographic();
  var scratchMatrix$3 = new Matrix4();
  var scratchCenter$4 = new Cartesian3();
  var scratchPosition$a = new Cartesian3();
  var scratchDirection = new Cartesian3();

  function updateDynamicScreenSpaceError(tileset, frameState) {
    var up;
    var direction;
    var height;
    var minimumHeight;
    var maximumHeight;

    var camera = frameState.camera;
    var root = tileset._root;
    var tileBoundingVolume = root.contentBoundingVolume;

    if (tileBoundingVolume instanceof TileBoundingRegion) {
      up = Cartesian3.normalize(camera.positionWC, scratchPositionNormal);
      direction = camera.directionWC;
      height = camera.positionCartographic.height;
      minimumHeight = tileBoundingVolume.minimumHeight;
      maximumHeight = tileBoundingVolume.maximumHeight;
    } else {
      // Transform camera position and direction into the local coordinate system of the tileset
      var transformLocal = Matrix4.inverseTransformation(
        root.computedTransform,
        scratchMatrix$3
      );
      var ellipsoid = frameState.mapProjection.ellipsoid;
      var boundingVolume = tileBoundingVolume.boundingVolume;
      var centerLocal = Matrix4.multiplyByPoint(
        transformLocal,
        boundingVolume.center,
        scratchCenter$4
      );
      if (Cartesian3.magnitude(centerLocal) > ellipsoid.minimumRadius) {
        // The tileset is defined in WGS84. Approximate the minimum and maximum height.
        var centerCartographic = Cartographic.fromCartesian(
          centerLocal,
          ellipsoid,
          scratchCartographic$7
        );
        up = Cartesian3.normalize(camera.positionWC, scratchPositionNormal);
        direction = camera.directionWC;
        height = camera.positionCartographic.height;
        minimumHeight = 0.0;
        maximumHeight = centerCartographic.height * 2.0;
      } else {
        // The tileset is defined in local coordinates (z-up)
        var positionLocal = Matrix4.multiplyByPoint(
          transformLocal,
          camera.positionWC,
          scratchPosition$a
        );
        up = Cartesian3.UNIT_Z;
        direction = Matrix4.multiplyByPointAsVector(
          transformLocal,
          camera.directionWC,
          scratchDirection
        );
        direction = Cartesian3.normalize(direction, direction);
        height = positionLocal.z;
        if (tileBoundingVolume instanceof TileOrientedBoundingBox) {
          // Assuming z-up, the last component stores the half-height of the box
          var boxHeight = root._header.boundingVolume.box[11];
          minimumHeight = centerLocal.z - boxHeight;
          maximumHeight = centerLocal.z + boxHeight;
        } else if (tileBoundingVolume instanceof TileBoundingSphere) {
          var radius = boundingVolume.radius;
          minimumHeight = centerLocal.z - radius;
          maximumHeight = centerLocal.z + radius;
        }
      }
    }

    // The range where the density starts to lessen. Start at the quarter height of the tileset.
    var heightFalloff = tileset.dynamicScreenSpaceErrorHeightFalloff;
    var heightClose =
      minimumHeight + (maximumHeight - minimumHeight) * heightFalloff;
    var heightFar = maximumHeight;

    var t = CesiumMath.clamp(
      (height - heightClose) / (heightFar - heightClose),
      0.0,
      1.0
    );

    // Increase density as the camera tilts towards the horizon
    var dot = Math.abs(Cartesian3.dot(direction, up));
    var horizonFactor = 1.0 - dot;

    // Weaken the horizon factor as the camera height increases, implying the camera is further away from the tileset.
    // The goal is to increase density for the "street view", not when viewing the tileset from a distance.
    horizonFactor = horizonFactor * (1.0 - t);

    var density = tileset.dynamicScreenSpaceErrorDensity;
    density *= horizonFactor;

    tileset._dynamicScreenSpaceErrorComputedDensity = density;
  }

  ///////////////////////////////////////////////////////////////////////////

  function requestContent(tileset, tile) {
    if (tile.hasEmptyContent) {
      return;
    }

    var statistics = tileset._statistics;
    var expired = tile.contentExpired;
    var requested = tile.requestContent();

    if (!requested) {
      ++statistics.numberOfAttemptedRequests;
      return;
    }

    if (expired) {
      if (tile.hasTilesetContent) {
        destroySubtree(tileset, tile);
      } else {
        statistics.decrementLoadCounts(tile.content);
        --statistics.numberOfTilesWithContentReady;
      }
    }

    ++statistics.numberOfPendingRequests;
    tileset._requestedTilesInFlight.push(tile);

    tile.contentReadyToProcessPromise.then(addToProcessingQueue(tileset, tile));
    tile.contentReadyPromise
      .then(handleTileSuccess(tileset, tile))
      .otherwise(handleTileFailure(tileset, tile));
  }

  function sortRequestByPriority(a, b) {
    return a._priority - b._priority;
  }

  /**
   * Perform any pass invariant tasks here. Called after the render pass.
   * @private
   */
  Cesium3DTileset.prototype.postPassesUpdate = function (frameState) {
    if (!this.ready) {
      return;
    }

    cancelOutOfViewRequests(this, frameState);
    raiseLoadProgressEvent(this, frameState);
    this._cache.unloadTiles(this, unloadTile);
  };

  /**
   * Perform any pass invariant tasks here. Called before any passes are executed.
   * @private
   */
  Cesium3DTileset.prototype.prePassesUpdate = function (frameState) {
    if (!this.ready) {
      return;
    }

    processTiles(this, frameState);

    // Update clipping planes
    var clippingPlanes = this._clippingPlanes;
    this._clippingPlanesOriginMatrixDirty = true;
    if (defined(clippingPlanes) && clippingPlanes.enabled) {
      clippingPlanes.update(frameState);
    }

    if (!defined(this._loadTimestamp)) {
      this._loadTimestamp = JulianDate.clone(frameState.time);
    }
    this._timeSinceLoad = Math.max(
      JulianDate.secondsDifference(frameState.time, this._loadTimestamp) * 1000,
      0.0
    );

    this._skipLevelOfDetail =
      this.skipLevelOfDetail &&
      !defined(this._classificationType) &&
      !this._disableSkipLevelOfDetail &&
      !this._allTilesAdditive;

    if (this.dynamicScreenSpaceError) {
      updateDynamicScreenSpaceError(this, frameState);
    }

    if (frameState.newFrame) {
      this._cache.reset();
    }
  };

  function cancelOutOfViewRequests(tileset, frameState) {
    var requestedTilesInFlight = tileset._requestedTilesInFlight;
    var removeCount = 0;
    var length = requestedTilesInFlight.length;
    for (var i = 0; i < length; ++i) {
      var tile = requestedTilesInFlight[i];

      // NOTE: This is framerate dependant so make sure the threshold check is small
      var outOfView = frameState.frameNumber - tile._touchedFrame >= 1;
      if (tile._contentState !== Cesium3DTileContentState$1.LOADING) {
        // No longer fetching from host, don't need to track it anymore. Gets marked as LOADING in Cesium3DTile::requestContent().
        ++removeCount;
        continue;
      } else if (outOfView) {
        // RequestScheduler will take care of cancelling it
        tile._request.cancel();
        ++removeCount;
        continue;
      }

      if (removeCount > 0) {
        requestedTilesInFlight[i - removeCount] = tile;
      }
    }

    requestedTilesInFlight.length -= removeCount;
  }

  function requestTiles(tileset, isAsync) {
    // Sort requests by priority before making any requests.
    // This makes it less likely that requests will be cancelled after being issued.
    var requestedTiles = tileset._requestedTiles;
    var length = requestedTiles.length;
    requestedTiles.sort(sortRequestByPriority);
    for (var i = 0; i < length; ++i) {
      requestContent(tileset, requestedTiles[i]);
    }
  }

  function addToProcessingQueue(tileset, tile) {
    return function () {
      tileset._processingQueue.push(tile);

      --tileset._statistics.numberOfPendingRequests;
      ++tileset._statistics.numberOfTilesProcessing;
    };
  }

  function handleTileFailure(tileset, tile) {
    return function (error) {
      var url = tile._contentResource.url;
      var message = defined(error.message) ? error.message : error.toString();
      if (tileset.tileFailed.numberOfListeners > 0) {
        tileset.tileFailed.raiseEvent({
          url: url,
          message: message,
        });
      } else {
        console.log("A 3D tile failed to load: " + url);
        console.log("Error: " + message);
      }
    };
  }

  function handleTileSuccess(tileset, tile) {
    return function () {
      --tileset._statistics.numberOfTilesProcessing;

      if (!tile.hasTilesetContent) {
        // RESEARCH_IDEA: ability to unload tiles (without content) for an
        // external tileset when all the tiles are unloaded.
        tileset._statistics.incrementLoadCounts(tile.content);
        ++tileset._statistics.numberOfTilesWithContentReady;
        ++tileset._statistics.numberOfLoadedTilesTotal;

        // Add to the tile cache. Previously expired tiles are already in the cache and won't get re-added.
        tileset._cache.add(tile);
      }

      tileset.tileLoad.raiseEvent(tile);
    };
  }

  function filterProcessingQueue(tileset) {
    var tiles = tileset._processingQueue;
    var length = tiles.length;

    var removeCount = 0;
    for (var i = 0; i < length; ++i) {
      var tile = tiles[i];
      if (tile._contentState !== Cesium3DTileContentState$1.PROCESSING) {
        ++removeCount;
        continue;
      }
      if (removeCount > 0) {
        tiles[i - removeCount] = tile;
      }
    }
    tiles.length -= removeCount;
  }

  function processTiles(tileset, frameState) {
    filterProcessingQueue(tileset);
    var tiles = tileset._processingQueue;
    var length = tiles.length;
    // Process tiles in the PROCESSING state so they will eventually move to the READY state.
    for (var i = 0; i < length; ++i) {
      tiles[i].process(tileset, frameState);
    }
  }

  ///////////////////////////////////////////////////////////////////////////

  var scratchCartesian$5 = new Cartesian3();

  var stringOptions = {
    maximumFractionDigits: 3,
  };

  function formatMemoryString(memorySizeInBytes) {
    var memoryInMegabytes = memorySizeInBytes / 1048576;
    if (memoryInMegabytes < 1.0) {
      return memoryInMegabytes.toLocaleString(undefined, stringOptions);
    }
    return Math.round(memoryInMegabytes).toLocaleString();
  }

  function computeTileLabelPosition(tile) {
    var boundingVolume = tile.boundingVolume.boundingVolume;
    var halfAxes = boundingVolume.halfAxes;
    var radius = boundingVolume.radius;

    var position = Cartesian3.clone(boundingVolume.center, scratchCartesian$5);
    if (defined(halfAxes)) {
      position.x += 0.75 * (halfAxes[0] + halfAxes[3] + halfAxes[6]);
      position.y += 0.75 * (halfAxes[1] + halfAxes[4] + halfAxes[7]);
      position.z += 0.75 * (halfAxes[2] + halfAxes[5] + halfAxes[8]);
    } else if (defined(radius)) {
      var normal = Cartesian3.normalize(boundingVolume.center, scratchCartesian$5);
      normal = Cartesian3.multiplyByScalar(
        normal,
        0.75 * radius,
        scratchCartesian$5
      );
      position = Cartesian3.add(normal, boundingVolume.center, scratchCartesian$5);
    }
    return position;
  }

  function addTileDebugLabel(tile, tileset, position) {
    var labelString = "";
    var attributes = 0;

    if (tileset.debugShowGeometricError) {
      labelString += "\nGeometric error: " + tile.geometricError;
      attributes++;
    }

    if (tileset.debugShowRenderingStatistics) {
      labelString += "\nCommands: " + tile.commandsLength;
      attributes++;

      // Don't display number of points or triangles if 0.
      var numberOfPoints = tile.content.pointsLength;
      if (numberOfPoints > 0) {
        labelString += "\nPoints: " + tile.content.pointsLength;
        attributes++;
      }

      var numberOfTriangles = tile.content.trianglesLength;
      if (numberOfTriangles > 0) {
        labelString += "\nTriangles: " + tile.content.trianglesLength;
        attributes++;
      }

      labelString += "\nFeatures: " + tile.content.featuresLength;
      attributes++;
    }

    if (tileset.debugShowMemoryUsage) {
      labelString +=
        "\nTexture Memory: " +
        formatMemoryString(tile.content.texturesByteLength);
      labelString +=
        "\nGeometry Memory: " +
        formatMemoryString(tile.content.geometryByteLength);
      attributes += 2;
    }

    if (tileset.debugShowUrl) {
      labelString += "\nUrl: " + tile._header.content.uri;
      attributes++;
    }

    var newLabel = {
      text: labelString.substring(1),
      position: position,
      font: 19 - attributes + "px sans-serif",
      showBackground: true,
      disableDepthTestDistance: Number.POSITIVE_INFINITY,
    };

    return tileset._tileDebugLabels.add(newLabel);
  }

  function updateTileDebugLabels(tileset, frameState) {
    var i;
    var tile;
    var selectedTiles = tileset._selectedTiles;
    var selectedLength = selectedTiles.length;
    var emptyTiles = tileset._emptyTiles;
    var emptyLength = emptyTiles.length;
    tileset._tileDebugLabels.removeAll();

    if (tileset.debugPickedTileLabelOnly) {
      if (defined(tileset.debugPickedTile)) {
        var position = defined(tileset.debugPickPosition)
          ? tileset.debugPickPosition
          : computeTileLabelPosition(tileset.debugPickedTile);
        var label = addTileDebugLabel(tileset.debugPickedTile, tileset, position);
        label.pixelOffset = new Cartesian2(15, -15); // Offset to avoid picking the label.
      }
    } else {
      for (i = 0; i < selectedLength; ++i) {
        tile = selectedTiles[i];
        addTileDebugLabel(tile, tileset, computeTileLabelPosition(tile));
      }
      for (i = 0; i < emptyLength; ++i) {
        tile = emptyTiles[i];
        if (tile.hasTilesetContent) {
          addTileDebugLabel(tile, tileset, computeTileLabelPosition(tile));
        }
      }
    }
    tileset._tileDebugLabels.update(frameState);
  }

  function updateTiles(tileset, frameState, passOptions) {
    tileset._styleEngine.applyStyle(tileset, passOptions);

    var isRender = passOptions.isRender;
    var statistics = tileset._statistics;
    var commandList = frameState.commandList;
    var numberOfInitialCommands = commandList.length;
    var selectedTiles = tileset._selectedTiles;
    var selectedLength = selectedTiles.length;
    var emptyTiles = tileset._emptyTiles;
    var emptyLength = emptyTiles.length;
    var tileVisible = tileset.tileVisible;
    var i;
    var tile;

    var bivariateVisibilityTest =
      tileset._skipLevelOfDetail &&
      tileset._hasMixedContent &&
      frameState.context.stencilBuffer &&
      selectedLength > 0;

    tileset._backfaceCommands.length = 0;

    if (bivariateVisibilityTest) {
      if (!defined(tileset._stencilClearCommand)) {
        tileset._stencilClearCommand = new ClearCommand({
          stencil: 0,
          pass: Pass$1.CESIUM_3D_TILE,
          renderState: RenderState.fromCache({
            stencilMask: StencilConstants$1.SKIP_LOD_MASK,
          }),
        });
      }
      commandList.push(tileset._stencilClearCommand);
    }

    var lengthBeforeUpdate = commandList.length;
    for (i = 0; i < selectedLength; ++i) {
      tile = selectedTiles[i];
      // Raise the tileVisible event before update in case the tileVisible event
      // handler makes changes that update needs to apply to WebGL resources
      if (isRender) {
        tileVisible.raiseEvent(tile);
      }
      tile.update(tileset, frameState, passOptions);
      statistics.incrementSelectionCounts(tile.content);
      ++statistics.selected;
    }
    for (i = 0; i < emptyLength; ++i) {
      tile = emptyTiles[i];
      tile.update(tileset, frameState, passOptions);
    }

    var addedCommandsLength = commandList.length - lengthBeforeUpdate;

    tileset._backfaceCommands.trim();

    if (bivariateVisibilityTest) {
      /*
       * Consider 'effective leaf' tiles as selected tiles that have no selected descendants. They may have children,
       * but they are currently our effective leaves because they do not have selected descendants. These tiles
       * are those where with tile._finalResolution === true.
       * Let 'unresolved' tiles be those with tile._finalResolution === false.
       *
       * 1. Render just the backfaces of unresolved tiles in order to lay down z
       * 2. Render all frontfaces wherever tile._selectionDepth > stencilBuffer.
       *    Replace stencilBuffer with tile._selectionDepth, when passing the z test.
       *    Because children are always drawn before ancestors {@link Cesium3DTilesetTraversal#traverseAndSelect},
       *    this effectively draws children first and does not draw ancestors if a descendant has already
       *    been drawn at that pixel.
       *    Step 1 prevents child tiles from appearing on top when they are truly behind ancestor content.
       *    If they are behind the backfaces of the ancestor, then they will not be drawn.
       *
       * NOTE: Step 2 sometimes causes visual artifacts when backfacing child content has some faces that
       * partially face the camera and are inside of the ancestor content. Because they are inside, they will
       * not be culled by the depth writes in Step 1, and because they partially face the camera, the stencil tests
       * will draw them on top of the ancestor content.
       *
       * NOTE: Because we always render backfaces of unresolved tiles, if the camera is looking at the backfaces
       * of an object, they will always be drawn while loading, even if backface culling is enabled.
       */

      var backfaceCommands = tileset._backfaceCommands.values;
      var backfaceCommandsLength = backfaceCommands.length;

      commandList.length += backfaceCommandsLength;

      // copy commands to the back of the commandList
      for (i = addedCommandsLength - 1; i >= 0; --i) {
        commandList[lengthBeforeUpdate + backfaceCommandsLength + i] =
          commandList[lengthBeforeUpdate + i];
      }

      // move backface commands to the front of the commandList
      for (i = 0; i < backfaceCommandsLength; ++i) {
        commandList[lengthBeforeUpdate + i] = backfaceCommands[i];
      }
    }

    // Number of commands added by each update above
    addedCommandsLength = commandList.length - numberOfInitialCommands;
    statistics.numberOfCommands = addedCommandsLength;

    // Only run EDL if simple attenuation is on
    if (
      isRender &&
      tileset.pointCloudShading.attenuation &&
      tileset.pointCloudShading.eyeDomeLighting &&
      addedCommandsLength > 0
    ) {
      tileset._pointCloudEyeDomeLighting.update(
        frameState,
        numberOfInitialCommands,
        tileset.pointCloudShading,
        tileset.boundingSphere
      );
    }

    if (isRender) {
      if (
        tileset.debugShowGeometricError ||
        tileset.debugShowRenderingStatistics ||
        tileset.debugShowMemoryUsage ||
        tileset.debugShowUrl
      ) {
        if (!defined(tileset._tileDebugLabels)) {
          tileset._tileDebugLabels = new LabelCollection();
        }
        updateTileDebugLabels(tileset, frameState);
      } else {
        tileset._tileDebugLabels =
          tileset._tileDebugLabels && tileset._tileDebugLabels.destroy();
      }
    }
  }

  var scratchStack$1 = [];

  function destroySubtree(tileset, tile) {
    var root = tile;
    var stack = scratchStack$1;
    stack.push(tile);
    while (stack.length > 0) {
      tile = stack.pop();
      var children = tile.children;
      var length = children.length;
      for (var i = 0; i < length; ++i) {
        stack.push(children[i]);
      }
      if (tile !== root) {
        destroyTile(tileset, tile);
        --tileset._statistics.numberOfTilesTotal;
      }
    }
    root.children = [];
  }

  function unloadTile(tileset, tile) {
    tileset.tileUnload.raiseEvent(tile);
    tileset._statistics.decrementLoadCounts(tile.content);
    --tileset._statistics.numberOfTilesWithContentReady;
    tile.unloadContent();
  }

  function destroyTile(tileset, tile) {
    tileset._cache.unloadTile(tileset, tile, unloadTile);
    tile.destroy();
  }

  /**
   * Unloads all tiles that weren't selected the previous frame.  This can be used to
   * explicitly manage the tile cache and reduce the total number of tiles loaded below
   * {@link Cesium3DTileset#maximumMemoryUsage}.
   * <p>
   * Tile unloads occur at the next frame to keep all the WebGL delete calls
   * within the render loop.
   * </p>
   */
  Cesium3DTileset.prototype.trimLoadedTiles = function () {
    this._cache.trim();
  };

  ///////////////////////////////////////////////////////////////////////////

  function raiseLoadProgressEvent(tileset, frameState) {
    var statistics = tileset._statistics;
    var statisticsLast = tileset._statisticsLast;

    var numberOfPendingRequests = statistics.numberOfPendingRequests;
    var numberOfTilesProcessing = statistics.numberOfTilesProcessing;
    var lastNumberOfPendingRequest = statisticsLast.numberOfPendingRequests;
    var lastNumberOfTilesProcessing = statisticsLast.numberOfTilesProcessing;

    Cesium3DTilesetStatistics.clone(statistics, statisticsLast);

    var progressChanged =
      numberOfPendingRequests !== lastNumberOfPendingRequest ||
      numberOfTilesProcessing !== lastNumberOfTilesProcessing;

    if (progressChanged) {
      frameState.afterRender.push(function () {
        tileset.loadProgress.raiseEvent(
          numberOfPendingRequests,
          numberOfTilesProcessing
        );
      });
    }

    tileset._tilesLoaded =
      statistics.numberOfPendingRequests === 0 &&
      statistics.numberOfTilesProcessing === 0 &&
      statistics.numberOfAttemptedRequests === 0;

    // Events are raised (added to the afterRender queue) here since promises
    // may resolve outside of the update loop that then raise events, e.g.,
    // model's readyPromise.
    if (progressChanged && tileset._tilesLoaded) {
      frameState.afterRender.push(function () {
        tileset.allTilesLoaded.raiseEvent();
      });
      if (!tileset._initialTilesLoaded) {
        tileset._initialTilesLoaded = true;
        frameState.afterRender.push(function () {
          tileset.initialTilesLoaded.raiseEvent();
        });
      }
    }
  }

  function resetMinimumMaximum(tileset) {
    tileset._heatmap.resetMinimumMaximum();
    tileset._minimumPriority.depth = Number.MAX_VALUE;
    tileset._maximumPriority.depth = -Number.MAX_VALUE;
    tileset._minimumPriority.foveatedFactor = Number.MAX_VALUE;
    tileset._maximumPriority.foveatedFactor = -Number.MAX_VALUE;
    tileset._minimumPriority.distance = Number.MAX_VALUE;
    tileset._maximumPriority.distance = -Number.MAX_VALUE;
    tileset._minimumPriority.reverseScreenSpaceError = Number.MAX_VALUE;
    tileset._maximumPriority.reverseScreenSpaceError = -Number.MAX_VALUE;
  }

  function detectModelMatrixChanged(tileset, frameState) {
    if (
      frameState.frameNumber !== tileset._updatedModelMatrixFrame ||
      !defined(tileset._previousModelMatrix)
    ) {
      tileset._updatedModelMatrixFrame = frameState.frameNumber;
      tileset._modelMatrixChanged = !Matrix4.equals(
        tileset.modelMatrix,
        tileset._previousModelMatrix
      );
      tileset._previousModelMatrix = Matrix4.clone(
        tileset.modelMatrix,
        tileset._previousModelMatrix
      );
    }
  }

  ///////////////////////////////////////////////////////////////////////////

  function update$4(tileset, frameState, passStatistics, passOptions) {
    if (frameState.mode === SceneMode$1.MORPHING) {
      return false;
    }

    if (!tileset.ready) {
      return false;
    }

    var statistics = tileset._statistics;
    statistics.clear();

    var isRender = passOptions.isRender;

    // Resets the visibility check for each pass
    ++tileset._updatedVisibilityFrame;

    // Update any tracked min max values
    resetMinimumMaximum(tileset);

    detectModelMatrixChanged(tileset, frameState);
    tileset._cullRequestsWhileMoving =
      tileset.cullRequestsWhileMoving && !tileset._modelMatrixChanged;

    var ready = passOptions.traversal.selectTiles(tileset, frameState);

    if (passOptions.requestTiles) {
      requestTiles(tileset);
    }

    updateTiles(tileset, frameState, passOptions);

    // Update pass statistics
    Cesium3DTilesetStatistics.clone(statistics, passStatistics);

    if (isRender) {
      var credits = tileset._credits;
      if (defined(credits) && statistics.selected !== 0) {
        var length = credits.length;
        for (var i = 0; i < length; ++i) {
          frameState.creditDisplay.addCredit(credits[i]);
        }
      }
    }

    return ready;
  }

  /**
   * @private
   */
  Cesium3DTileset.prototype.update = function (frameState) {
    this.updateForPass(frameState, frameState.tilesetPassState);
  };

  /**
   * @private
   */
  Cesium3DTileset.prototype.updateForPass = function (
    frameState,
    tilesetPassState
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("frameState", frameState);
    Check.typeOf.object("tilesetPassState", tilesetPassState);
    //>>includeEnd('debug');

    var pass = tilesetPassState.pass;
    if (
      (pass === Cesium3DTilePass$1.PRELOAD &&
        (!this.preloadWhenHidden || this.show)) ||
      (pass === Cesium3DTilePass$1.PRELOAD_FLIGHT &&
        (!this.preloadFlightDestinations ||
          (!this.show && !this.preloadWhenHidden))) ||
      (pass === Cesium3DTilePass$1.REQUEST_RENDER_MODE_DEFER_CHECK &&
        ((!this._cullRequestsWhileMoving && this.foveatedTimeDelay <= 0) ||
          !this.show))
    ) {
      return;
    }

    var originalCommandList = frameState.commandList;
    var originalCamera = frameState.camera;
    var originalCullingVolume = frameState.cullingVolume;

    tilesetPassState.ready = false;

    var passOptions = Cesium3DTilePass$1.getPassOptions(pass);
    var ignoreCommands = passOptions.ignoreCommands;

    var commandList = defaultValue(
      tilesetPassState.commandList,
      originalCommandList
    );
    var commandStart = commandList.length;

    frameState.commandList = commandList;
    frameState.camera = defaultValue(tilesetPassState.camera, originalCamera);
    frameState.cullingVolume = defaultValue(
      tilesetPassState.cullingVolume,
      originalCullingVolume
    );

    var passStatistics = this._statisticsPerPass[pass];

    if (this.show || ignoreCommands) {
      this._pass = pass;
      tilesetPassState.ready = update$4(
        this,
        frameState,
        passStatistics,
        passOptions
      );
    }

    if (ignoreCommands) {
      commandList.length = commandStart;
    }

    frameState.commandList = originalCommandList;
    frameState.camera = originalCamera;
    frameState.cullingVolume = originalCullingVolume;
  };

  /**
   * <code>true</code> if the tileset JSON file lists the extension in extensionsUsed; otherwise, <code>false</code>.
   * @param {String} extensionName The name of the extension to check.
   *
   * @returns {Boolean} <code>true</code> if the tileset JSON file lists the extension in extensionsUsed; otherwise, <code>false</code>.
   */
  Cesium3DTileset.prototype.hasExtension = function (extensionName) {
    if (!defined(this._extensionsUsed)) {
      return false;
    }

    return this._extensionsUsed.indexOf(extensionName) > -1;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Cesium3DTileset#destroy
   */
  Cesium3DTileset.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * tileset = tileset && tileset.destroy();
   *
   * @see Cesium3DTileset#isDestroyed
   */
  Cesium3DTileset.prototype.destroy = function () {
    this._tileDebugLabels =
      this._tileDebugLabels && this._tileDebugLabels.destroy();
    this._clippingPlanes = this._clippingPlanes && this._clippingPlanes.destroy();

    // Traverse the tree and destroy all tiles
    if (defined(this._root)) {
      var stack = scratchStack$1;
      stack.push(this._root);

      while (stack.length > 0) {
        var tile = stack.pop();
        tile.destroy();

        var children = tile.children;
        var length = children.length;
        for (var i = 0; i < length; ++i) {
          stack.push(children[i]);
        }
      }
    }

    this._root = undefined;
    return destroyObject(this);
  };

  var modelMatrixScratch = new Matrix4();

  /**
   * A {@link Visualizer} which maps {@link Entity#tileset} to a {@link Cesium3DTileset}.
   * @alias Cesium3DTilesetVisualizer
   * @constructor
   *
   * @param {Scene} scene The scene the primitives will be rendered in.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   */
  function Cesium3DTilesetVisualizer(scene, entityCollection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    if (!defined(entityCollection)) {
      throw new DeveloperError("entityCollection is required.");
    }
    //>>includeEnd('debug');

    entityCollection.collectionChanged.addEventListener(
      Cesium3DTilesetVisualizer.prototype._onCollectionChanged,
      this
    );

    this._scene = scene;
    this._primitives = scene.primitives;
    this._entityCollection = entityCollection;
    this._tilesetHash = {};
    this._entitiesToVisualize = new AssociativeArray();
    this._onCollectionChanged(entityCollection, entityCollection.values, [], []);
  }

  /**
   * Updates models created this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} This function always returns true.
   */
  Cesium3DTilesetVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var entities = this._entitiesToVisualize.values;
    var tilesetHash = this._tilesetHash;
    var primitives = this._primitives;

    for (var i = 0, len = entities.length; i < len; i++) {
      var entity = entities[i];
      var tilesetGraphics = entity._tileset;

      var resource;
      var tilesetData = tilesetHash[entity.id];
      var show =
        entity.isShowing &&
        entity.isAvailable(time) &&
        Property.getValueOrDefault(tilesetGraphics._show, time, true);

      var modelMatrix;
      if (show) {
        modelMatrix = entity.computeModelMatrix(time, modelMatrixScratch);
        resource = Resource.createIfNeeded(
          Property.getValueOrUndefined(tilesetGraphics._uri, time)
        );
      }

      if (!show) {
        if (defined(tilesetData)) {
          tilesetData.tilesetPrimitive.show = false;
        }
        continue;
      }

      var tileset = defined(tilesetData)
        ? tilesetData.tilesetPrimitive
        : undefined;
      if (!defined(tileset) || resource.url !== tilesetData.url) {
        if (defined(tileset)) {
          primitives.removeAndDestroy(tileset);
          delete tilesetHash[entity.id];
        }
        tileset = new Cesium3DTileset({
          url: resource,
        });
        tileset.id = entity;
        primitives.add(tileset);

        tilesetData = {
          tilesetPrimitive: tileset,
          url: resource.url,
          loadFail: false,
        };
        tilesetHash[entity.id] = tilesetData;

        checkLoad(tileset, entity, tilesetHash);
      }

      tileset.show = true;
      if (defined(modelMatrix)) {
        tileset.modelMatrix = modelMatrix;
      }
      tileset.maximumScreenSpaceError = Property.getValueOrDefault(
        tilesetGraphics.maximumScreenSpaceError,
        time,
        tileset.maximumScreenSpaceError
      );
    }

    return true;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  Cesium3DTilesetVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  Cesium3DTilesetVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      Cesium3DTilesetVisualizer.prototype._onCollectionChanged,
      this
    );
    var entities = this._entitiesToVisualize.values;
    var tilesetHash = this._tilesetHash;
    var primitives = this._primitives;
    for (var i = entities.length - 1; i > -1; i--) {
      removeTileset(this, entities[i], tilesetHash, primitives);
    }
    return destroyObject(this);
  };

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  Cesium3DTilesetVisualizer.prototype.getBoundingSphere = function (
    entity,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var tilesetData = this._tilesetHash[entity.id];
    if (!defined(tilesetData) || tilesetData.loadFail) {
      return BoundingSphereState$1.FAILED;
    }

    var primitive = tilesetData.tilesetPrimitive;
    if (!defined(primitive) || !primitive.show) {
      return BoundingSphereState$1.FAILED;
    }

    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }

    BoundingSphere.clone(primitive.boundingSphere, result);

    return BoundingSphereState$1.DONE;
  };

  /**
   * @private
   */
  Cesium3DTilesetVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed,
    changed
  ) {
    var i;
    var entity;
    var entities = this._entitiesToVisualize;
    var tilesetHash = this._tilesetHash;
    var primitives = this._primitives;

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      if (defined(entity._tileset)) {
        entities.set(entity.id, entity);
      }
    }

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      if (defined(entity._tileset)) {
        entities.set(entity.id, entity);
      } else {
        removeTileset(this, entity, tilesetHash, primitives);
        entities.remove(entity.id);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      removeTileset(this, entity, tilesetHash, primitives);
      entities.remove(entity.id);
    }
  };

  function removeTileset(visualizer, entity, tilesetHash, primitives) {
    var tilesetData = tilesetHash[entity.id];
    if (defined(tilesetData)) {
      primitives.removeAndDestroy(tilesetData.tilesetPrimitive);
      delete tilesetHash[entity.id];
    }
  }

  function checkLoad(primitive, entity, tilesetHash) {
    primitive.readyPromise.otherwise(function (error) {
      console.error(error);
      tilesetHash[entity.id].loadFail = true;
    });
  }

  var defaultEvenColor = Color.WHITE;
  var defaultOddColor = Color.BLACK;
  var defaultRepeat$1 = new Cartesian2(2.0, 2.0);

  /**
   * A {@link MaterialProperty} that maps to checkerboard {@link Material} uniforms.
   * @alias CheckerboardMaterialProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|Color} [options.evenColor=Color.WHITE] A Property specifying the first {@link Color}.
   * @param {Property|Color} [options.oddColor=Color.BLACK] A Property specifying the second {@link Color}.
   * @param {Property|Cartesian2} [options.repeat=new Cartesian2(2.0, 2.0)] A {@link Cartesian2} Property specifying how many times the tiles repeat in each direction.
   */
  function CheckerboardMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._evenColor = undefined;
    this._evenColorSubscription = undefined;
    this._oddColor = undefined;
    this._oddColorSubscription = undefined;
    this._repeat = undefined;
    this._repeatSubscription = undefined;

    this.evenColor = options.evenColor;
    this.oddColor = options.oddColor;
    this.repeat = options.repeat;
  }

  Object.defineProperties(CheckerboardMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof CheckerboardMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._evenColor) && //
          Property.isConstant(this._oddColor) && //
          Property.isConstant(this._repeat)
        );
      },
    },

    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof CheckerboardMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the Property specifying the first {@link Color}.
     * @memberof CheckerboardMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    evenColor: createPropertyDescriptor("evenColor"),

    /**
     * Gets or sets the Property specifying the second {@link Color}.
     * @memberof CheckerboardMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    oddColor: createPropertyDescriptor("oddColor"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying how many times the tiles repeat in each direction.
     * @memberof CheckerboardMaterialProperty.prototype
     * @type {Property|undefined}
     * @default new Cartesian2(2.0, 2.0)
     */
    repeat: createPropertyDescriptor("repeat"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  CheckerboardMaterialProperty.prototype.getType = function (time) {
    return "Checkerboard";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  CheckerboardMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.lightColor = Property.getValueOrClonedDefault(
      this._evenColor,
      time,
      defaultEvenColor,
      result.lightColor
    );
    result.darkColor = Property.getValueOrClonedDefault(
      this._oddColor,
      time,
      defaultOddColor,
      result.darkColor
    );
    result.repeat = Property.getValueOrDefault(this._repeat, time, defaultRepeat$1);
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  CheckerboardMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof CheckerboardMaterialProperty && //
      Property.equals(this._evenColor, other._evenColor) && //
      Property.equals(this._oddColor, other._oddColor) && //
        Property.equals(this._repeat, other._repeat))
    );
  };

  var entityOptionsScratch = {
    id: undefined,
  };

  function fireChangedEvent(collection) {
    if (collection._firing) {
      collection._refire = true;
      return;
    }

    if (collection._suspendCount === 0) {
      var added = collection._addedEntities;
      var removed = collection._removedEntities;
      var changed = collection._changedEntities;
      if (changed.length !== 0 || added.length !== 0 || removed.length !== 0) {
        collection._firing = true;
        do {
          collection._refire = false;
          var addedArray = added.values.slice(0);
          var removedArray = removed.values.slice(0);
          var changedArray = changed.values.slice(0);

          added.removeAll();
          removed.removeAll();
          changed.removeAll();
          collection._collectionChanged.raiseEvent(
            collection,
            addedArray,
            removedArray,
            changedArray
          );
        } while (collection._refire);
        collection._firing = false;
      }
    }
  }

  /**
   * An observable collection of {@link Entity} instances where each entity has a unique id.
   * @alias EntityCollection
   * @constructor
   *
   * @param {DataSource|CompositeEntityCollection} [owner] The data source (or composite entity collection) which created this collection.
   */
  function EntityCollection(owner) {
    this._owner = owner;
    this._entities = new AssociativeArray();
    this._addedEntities = new AssociativeArray();
    this._removedEntities = new AssociativeArray();
    this._changedEntities = new AssociativeArray();
    this._suspendCount = 0;
    this._collectionChanged = new Event();
    this._id = createGuid();
    this._show = true;
    this._firing = false;
    this._refire = false;
  }

  /**
   * Prevents {@link EntityCollection#collectionChanged} events from being raised
   * until a corresponding call is made to {@link EntityCollection#resumeEvents}, at which
   * point a single event will be raised that covers all suspended operations.
   * This allows for many items to be added and removed efficiently.
   * This function can be safely called multiple times as long as there
   * are corresponding calls to {@link EntityCollection#resumeEvents}.
   */
  EntityCollection.prototype.suspendEvents = function () {
    this._suspendCount++;
  };

  /**
   * Resumes raising {@link EntityCollection#collectionChanged} events immediately
   * when an item is added or removed.  Any modifications made while while events were suspended
   * will be triggered as a single event when this function is called.
   * This function is reference counted and can safely be called multiple times as long as there
   * are corresponding calls to {@link EntityCollection#resumeEvents}.
   *
   * @exception {DeveloperError} resumeEvents can not be called before suspendEvents.
   */
  EntityCollection.prototype.resumeEvents = function () {
    //>>includeStart('debug', pragmas.debug);
    if (this._suspendCount === 0) {
      throw new DeveloperError(
        "resumeEvents can not be called before suspendEvents."
      );
    }
    //>>includeEnd('debug');

    this._suspendCount--;
    fireChangedEvent(this);
  };

  /**
   * The signature of the event generated by {@link EntityCollection#collectionChanged}.
   * @function
   *
   * @param {EntityCollection} collection The collection that triggered the event.
   * @param {Entity[]} added The array of {@link Entity} instances that have been added to the collection.
   * @param {Entity[]} removed The array of {@link Entity} instances that have been removed from the collection.
   * @param {Entity[]} changed The array of {@link Entity} instances that have been modified.
   */
  EntityCollection.collectionChangedEventCallback = undefined;

  Object.defineProperties(EntityCollection.prototype, {
    /**
     * Gets the event that is fired when entities are added or removed from the collection.
     * The generated event is a {@link EntityCollection.collectionChangedEventCallback}.
     * @memberof EntityCollection.prototype
     * @readonly
     * @type {Event}
     */
    collectionChanged: {
      get: function () {
        return this._collectionChanged;
      },
    },
    /**
     * Gets a globally unique identifier for this collection.
     * @memberof EntityCollection.prototype
     * @readonly
     * @type {String}
     */
    id: {
      get: function () {
        return this._id;
      },
    },
    /**
     * Gets the array of Entity instances in the collection.
     * This array should not be modified directly.
     * @memberof EntityCollection.prototype
     * @readonly
     * @type {Entity[]}
     */
    values: {
      get: function () {
        return this._entities.values;
      },
    },
    /**
     * Gets whether or not this entity collection should be
     * displayed.  When true, each entity is only displayed if
     * its own show property is also true.
     * @memberof EntityCollection.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (value === this._show) {
          return;
        }

        //Since entity.isShowing includes the EntityCollection.show state
        //in its calculation, we need to loop over the entities array
        //twice, once to get the old showing value and a second time
        //to raise the changed event.
        this.suspendEvents();

        var i;
        var oldShows = [];
        var entities = this._entities.values;
        var entitiesLength = entities.length;

        for (i = 0; i < entitiesLength; i++) {
          oldShows.push(entities[i].isShowing);
        }

        this._show = value;

        for (i = 0; i < entitiesLength; i++) {
          var oldShow = oldShows[i];
          var entity = entities[i];
          if (oldShow !== entity.isShowing) {
            entity.definitionChanged.raiseEvent(
              entity,
              "isShowing",
              entity.isShowing,
              oldShow
            );
          }
        }

        this.resumeEvents();
      },
    },
    /**
     * Gets the owner of this entity collection, ie. the data source or composite entity collection which created it.
     * @memberof EntityCollection.prototype
     * @readonly
     * @type {DataSource|CompositeEntityCollection}
     */
    owner: {
      get: function () {
        return this._owner;
      },
    },
  });

  /**
   * Computes the maximum availability of the entities in the collection.
   * If the collection contains a mix of infinitely available data and non-infinite data,
   * it will return the interval pertaining to the non-infinite data only.  If all
   * data is infinite, an infinite interval will be returned.
   *
   * @returns {TimeInterval} The availability of entities in the collection.
   */
  EntityCollection.prototype.computeAvailability = function () {
    var startTime = Iso8601.MAXIMUM_VALUE;
    var stopTime = Iso8601.MINIMUM_VALUE;
    var entities = this._entities.values;
    for (var i = 0, len = entities.length; i < len; i++) {
      var entity = entities[i];
      var availability = entity.availability;
      if (defined(availability)) {
        var start = availability.start;
        var stop = availability.stop;
        if (
          JulianDate.lessThan(start, startTime) &&
          !start.equals(Iso8601.MINIMUM_VALUE)
        ) {
          startTime = start;
        }
        if (
          JulianDate.greaterThan(stop, stopTime) &&
          !stop.equals(Iso8601.MAXIMUM_VALUE)
        ) {
          stopTime = stop;
        }
      }
    }

    if (Iso8601.MAXIMUM_VALUE.equals(startTime)) {
      startTime = Iso8601.MINIMUM_VALUE;
    }
    if (Iso8601.MINIMUM_VALUE.equals(stopTime)) {
      stopTime = Iso8601.MAXIMUM_VALUE;
    }
    return new TimeInterval({
      start: startTime,
      stop: stopTime,
    });
  };

  /**
   * Add an entity to the collection.
   *
   * @param {Entity | Entity.ConstructorOptions} entity The entity to be added.
   * @returns {Entity} The entity that was added.
   * @exception {DeveloperError} An entity with <entity.id> already exists in this collection.
   */
  EntityCollection.prototype.add = function (entity) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required.");
    }
    //>>includeEnd('debug');

    if (!(entity instanceof Entity)) {
      entity = new Entity(entity);
    }

    var id = entity.id;
    var entities = this._entities;
    if (entities.contains(id)) {
      throw new RuntimeError(
        "An entity with id " + id + " already exists in this collection."
      );
    }

    entity.entityCollection = this;
    entities.set(id, entity);

    if (!this._removedEntities.remove(id)) {
      this._addedEntities.set(id, entity);
    }
    entity.definitionChanged.addEventListener(
      EntityCollection.prototype._onEntityDefinitionChanged,
      this
    );

    fireChangedEvent(this);
    return entity;
  };

  /**
   * Removes an entity from the collection.
   *
   * @param {Entity} entity The entity to be removed.
   * @returns {Boolean} true if the item was removed, false if it did not exist in the collection.
   */
  EntityCollection.prototype.remove = function (entity) {
    if (!defined(entity)) {
      return false;
    }
    return this.removeById(entity.id);
  };

  /**
   * Returns true if the provided entity is in this collection, false otherwise.
   *
   * @param {Entity} entity The entity.
   * @returns {Boolean} true if the provided entity is in this collection, false otherwise.
   */
  EntityCollection.prototype.contains = function (entity) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required");
    }
    //>>includeEnd('debug');
    return this._entities.get(entity.id) === entity;
  };

  /**
   * Removes an entity with the provided id from the collection.
   *
   * @param {String} id The id of the entity to remove.
   * @returns {Boolean} true if the item was removed, false if no item with the provided id existed in the collection.
   */
  EntityCollection.prototype.removeById = function (id) {
    if (!defined(id)) {
      return false;
    }

    var entities = this._entities;
    var entity = entities.get(id);
    if (!this._entities.remove(id)) {
      return false;
    }

    if (!this._addedEntities.remove(id)) {
      this._removedEntities.set(id, entity);
      this._changedEntities.remove(id);
    }
    this._entities.remove(id);
    entity.definitionChanged.removeEventListener(
      EntityCollection.prototype._onEntityDefinitionChanged,
      this
    );
    fireChangedEvent(this);

    return true;
  };

  /**
   * Removes all Entities from the collection.
   */
  EntityCollection.prototype.removeAll = function () {
    //The event should only contain items added before events were suspended
    //and the contents of the collection.
    var entities = this._entities;
    var entitiesLength = entities.length;
    var array = entities.values;

    var addedEntities = this._addedEntities;
    var removed = this._removedEntities;

    for (var i = 0; i < entitiesLength; i++) {
      var existingItem = array[i];
      var existingItemId = existingItem.id;
      var addedItem = addedEntities.get(existingItemId);
      if (!defined(addedItem)) {
        existingItem.definitionChanged.removeEventListener(
          EntityCollection.prototype._onEntityDefinitionChanged,
          this
        );
        removed.set(existingItemId, existingItem);
      }
    }

    entities.removeAll();
    addedEntities.removeAll();
    this._changedEntities.removeAll();
    fireChangedEvent(this);
  };

  /**
   * Gets an entity with the specified id.
   *
   * @param {String} id The id of the entity to retrieve.
   * @returns {Entity|undefined} The entity with the provided id or undefined if the id did not exist in the collection.
   */
  EntityCollection.prototype.getById = function (id) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required.");
    }
    //>>includeEnd('debug');

    return this._entities.get(id);
  };

  /**
   * Gets an entity with the specified id or creates it and adds it to the collection if it does not exist.
   *
   * @param {String} id The id of the entity to retrieve or create.
   * @returns {Entity} The new or existing object.
   */
  EntityCollection.prototype.getOrCreateEntity = function (id) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(id)) {
      throw new DeveloperError("id is required.");
    }
    //>>includeEnd('debug');

    var entity = this._entities.get(id);
    if (!defined(entity)) {
      entityOptionsScratch.id = id;
      entity = new Entity(entityOptionsScratch);
      this.add(entity);
    }
    return entity;
  };

  EntityCollection.prototype._onEntityDefinitionChanged = function (entity) {
    var id = entity.id;
    if (!this._addedEntities.contains(id)) {
      this._changedEntities.set(id, entity);
    }
    fireChangedEvent(this);
  };

  var entityOptionsScratch$1 = {
    id: undefined,
  };
  var entityIdScratch = new Array(2);

  function clean(entity) {
    var propertyNames = entity.propertyNames;
    var propertyNamesLength = propertyNames.length;
    for (var i = 0; i < propertyNamesLength; i++) {
      entity[propertyNames[i]] = undefined;
    }
    entity._name = undefined;
    entity._availability = undefined;
  }

  function subscribeToEntity(that, eventHash, collectionId, entity) {
    entityIdScratch[0] = collectionId;
    entityIdScratch[1] = entity.id;
    eventHash[
      JSON.stringify(entityIdScratch)
    ] = entity.definitionChanged.addEventListener(
      CompositeEntityCollection.prototype._onDefinitionChanged,
      that
    );
  }

  function unsubscribeFromEntity(that, eventHash, collectionId, entity) {
    entityIdScratch[0] = collectionId;
    entityIdScratch[1] = entity.id;
    var id = JSON.stringify(entityIdScratch);
    eventHash[id]();
    eventHash[id] = undefined;
  }

  function recomposite(that) {
    that._shouldRecomposite = true;
    if (that._suspendCount !== 0) {
      return;
    }

    var collections = that._collections;
    var collectionsLength = collections.length;

    var collectionsCopy = that._collectionsCopy;
    var collectionsCopyLength = collectionsCopy.length;

    var i;
    var entity;
    var entities;
    var iEntities;
    var collection;
    var composite = that._composite;
    var newEntities = new EntityCollection(that);
    var eventHash = that._eventHash;
    var collectionId;

    for (i = 0; i < collectionsCopyLength; i++) {
      collection = collectionsCopy[i];
      collection.collectionChanged.removeEventListener(
        CompositeEntityCollection.prototype._onCollectionChanged,
        that
      );
      entities = collection.values;
      collectionId = collection.id;
      for (iEntities = entities.length - 1; iEntities > -1; iEntities--) {
        entity = entities[iEntities];
        unsubscribeFromEntity(that, eventHash, collectionId, entity);
      }
    }

    for (i = collectionsLength - 1; i >= 0; i--) {
      collection = collections[i];
      collection.collectionChanged.addEventListener(
        CompositeEntityCollection.prototype._onCollectionChanged,
        that
      );

      //Merge all of the existing entities.
      entities = collection.values;
      collectionId = collection.id;
      for (iEntities = entities.length - 1; iEntities > -1; iEntities--) {
        entity = entities[iEntities];
        subscribeToEntity(that, eventHash, collectionId, entity);

        var compositeEntity = newEntities.getById(entity.id);
        if (!defined(compositeEntity)) {
          compositeEntity = composite.getById(entity.id);
          if (!defined(compositeEntity)) {
            entityOptionsScratch$1.id = entity.id;
            compositeEntity = new Entity(entityOptionsScratch$1);
          } else {
            clean(compositeEntity);
          }
          newEntities.add(compositeEntity);
        }
        compositeEntity.merge(entity);
      }
    }
    that._collectionsCopy = collections.slice(0);

    composite.suspendEvents();
    composite.removeAll();
    var newEntitiesArray = newEntities.values;
    for (i = 0; i < newEntitiesArray.length; i++) {
      composite.add(newEntitiesArray[i]);
    }
    composite.resumeEvents();
  }

  /**
   * Non-destructively composites multiple {@link EntityCollection} instances into a single collection.
   * If a Entity with the same ID exists in multiple collections, it is non-destructively
   * merged into a single new entity instance.  If an entity has the same property in multiple
   * collections, the property of the Entity in the last collection of the list it
   * belongs to is used.  CompositeEntityCollection can be used almost anywhere that a
   * EntityCollection is used.
   *
   * @alias CompositeEntityCollection
   * @constructor
   *
   * @param {EntityCollection[]} [collections] The initial list of EntityCollection instances to merge.
   * @param {DataSource|CompositeEntityCollection} [owner] The data source (or composite entity collection) which created this collection.
   */
  function CompositeEntityCollection(collections, owner) {
    this._owner = owner;
    this._composite = new EntityCollection(this);
    this._suspendCount = 0;
    this._collections = defined(collections) ? collections.slice() : [];
    this._collectionsCopy = [];
    this._id = createGuid();
    this._eventHash = {};
    recomposite(this);
    this._shouldRecomposite = false;
  }

  Object.defineProperties(CompositeEntityCollection.prototype, {
    /**
     * Gets the event that is fired when entities are added or removed from the collection.
     * The generated event is a {@link EntityCollection.collectionChangedEventCallback}.
     * @memberof CompositeEntityCollection.prototype
     * @readonly
     * @type {Event}
     */
    collectionChanged: {
      get: function () {
        return this._composite._collectionChanged;
      },
    },
    /**
     * Gets a globally unique identifier for this collection.
     * @memberof CompositeEntityCollection.prototype
     * @readonly
     * @type {String}
     */
    id: {
      get: function () {
        return this._id;
      },
    },
    /**
     * Gets the array of Entity instances in the collection.
     * This array should not be modified directly.
     * @memberof CompositeEntityCollection.prototype
     * @readonly
     * @type {Entity[]}
     */
    values: {
      get: function () {
        return this._composite.values;
      },
    },
    /**
     * Gets the owner of this composite entity collection, ie. the data source or composite entity collection which created it.
     * @memberof CompositeEntityCollection.prototype
     * @readonly
     * @type {DataSource|CompositeEntityCollection}
     */
    owner: {
      get: function () {
        return this._owner;
      },
    },
  });

  /**
   * Adds a collection to the composite.
   *
   * @param {EntityCollection} collection the collection to add.
   * @param {Number} [index] the index to add the collection at.  If omitted, the collection will
   *                         added on top of all existing collections.
   *
   * @exception {DeveloperError} index, if supplied, must be greater than or equal to zero and less than or equal to the number of collections.
   */
  CompositeEntityCollection.prototype.addCollection = function (
    collection,
    index
  ) {
    var hasIndex = defined(index);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(collection)) {
      throw new DeveloperError("collection is required.");
    }
    if (hasIndex) {
      if (index < 0) {
        throw new DeveloperError("index must be greater than or equal to zero.");
      } else if (index > this._collections.length) {
        throw new DeveloperError(
          "index must be less than or equal to the number of collections."
        );
      }
    }
    //>>includeEnd('debug');

    if (!hasIndex) {
      index = this._collections.length;
      this._collections.push(collection);
    } else {
      this._collections.splice(index, 0, collection);
    }

    recomposite(this);
  };

  /**
   * Removes a collection from this composite, if present.
   *
   * @param {EntityCollection} collection The collection to remove.
   * @returns {Boolean} true if the collection was in the composite and was removed,
   *                    false if the collection was not in the composite.
   */
  CompositeEntityCollection.prototype.removeCollection = function (collection) {
    var index = this._collections.indexOf(collection);
    if (index !== -1) {
      this._collections.splice(index, 1);
      recomposite(this);
      return true;
    }
    return false;
  };

  /**
   * Removes all collections from this composite.
   */
  CompositeEntityCollection.prototype.removeAllCollections = function () {
    this._collections.length = 0;
    recomposite(this);
  };

  /**
   * Checks to see if the composite contains a given collection.
   *
   * @param {EntityCollection} collection the collection to check for.
   * @returns {Boolean} true if the composite contains the collection, false otherwise.
   */
  CompositeEntityCollection.prototype.containsCollection = function (collection) {
    return this._collections.indexOf(collection) !== -1;
  };

  /**
   * Returns true if the provided entity is in this collection, false otherwise.
   *
   * @param {Entity} entity The entity.
   * @returns {Boolean} true if the provided entity is in this collection, false otherwise.
   */
  CompositeEntityCollection.prototype.contains = function (entity) {
    return this._composite.contains(entity);
  };

  /**
   * Determines the index of a given collection in the composite.
   *
   * @param {EntityCollection} collection The collection to find the index of.
   * @returns {Number} The index of the collection in the composite, or -1 if the collection does not exist in the composite.
   */
  CompositeEntityCollection.prototype.indexOfCollection = function (collection) {
    return this._collections.indexOf(collection);
  };

  /**
   * Gets a collection by index from the composite.
   *
   * @param {Number} index the index to retrieve.
   */
  CompositeEntityCollection.prototype.getCollection = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.", "index");
    }
    //>>includeEnd('debug');

    return this._collections[index];
  };

  /**
   * Gets the number of collections in this composite.
   */
  CompositeEntityCollection.prototype.getCollectionsLength = function () {
    return this._collections.length;
  };

  function getCollectionIndex(collections, collection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(collection)) {
      throw new DeveloperError("collection is required.");
    }
    //>>includeEnd('debug');

    var index = collections.indexOf(collection);

    //>>includeStart('debug', pragmas.debug);
    if (index === -1) {
      throw new DeveloperError("collection is not in this composite.");
    }
    //>>includeEnd('debug');

    return index;
  }

  function swapCollections(composite, i, j) {
    var arr = composite._collections;
    i = CesiumMath.clamp(i, 0, arr.length - 1);
    j = CesiumMath.clamp(j, 0, arr.length - 1);

    if (i === j) {
      return;
    }

    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;

    recomposite(composite);
  }

  /**
   * Raises a collection up one position in the composite.
   *
   * @param {EntityCollection} collection the collection to move.
   *
   * @exception {DeveloperError} collection is not in this composite.
   */
  CompositeEntityCollection.prototype.raiseCollection = function (collection) {
    var index = getCollectionIndex(this._collections, collection);
    swapCollections(this, index, index + 1);
  };

  /**
   * Lowers a collection down one position in the composite.
   *
   * @param {EntityCollection} collection the collection to move.
   *
   * @exception {DeveloperError} collection is not in this composite.
   */
  CompositeEntityCollection.prototype.lowerCollection = function (collection) {
    var index = getCollectionIndex(this._collections, collection);
    swapCollections(this, index, index - 1);
  };

  /**
   * Raises a collection to the top of the composite.
   *
   * @param {EntityCollection} collection the collection to move.
   *
   * @exception {DeveloperError} collection is not in this composite.
   */
  CompositeEntityCollection.prototype.raiseCollectionToTop = function (
    collection
  ) {
    var index = getCollectionIndex(this._collections, collection);
    if (index === this._collections.length - 1) {
      return;
    }
    this._collections.splice(index, 1);
    this._collections.push(collection);

    recomposite(this);
  };

  /**
   * Lowers a collection to the bottom of the composite.
   *
   * @param {EntityCollection} collection the collection to move.
   *
   * @exception {DeveloperError} collection is not in this composite.
   */
  CompositeEntityCollection.prototype.lowerCollectionToBottom = function (
    collection
  ) {
    var index = getCollectionIndex(this._collections, collection);
    if (index === 0) {
      return;
    }
    this._collections.splice(index, 1);
    this._collections.splice(0, 0, collection);

    recomposite(this);
  };

  /**
   * Prevents {@link EntityCollection#collectionChanged} events from being raised
   * until a corresponding call is made to {@link EntityCollection#resumeEvents}, at which
   * point a single event will be raised that covers all suspended operations.
   * This allows for many items to be added and removed efficiently.
   * While events are suspended, recompositing of the collections will
   * also be suspended, as this can be a costly operation.
   * This function can be safely called multiple times as long as there
   * are corresponding calls to {@link EntityCollection#resumeEvents}.
   */
  CompositeEntityCollection.prototype.suspendEvents = function () {
    this._suspendCount++;
    this._composite.suspendEvents();
  };

  /**
   * Resumes raising {@link EntityCollection#collectionChanged} events immediately
   * when an item is added or removed.  Any modifications made while while events were suspended
   * will be triggered as a single event when this function is called.  This function also ensures
   * the collection is recomposited if events are also resumed.
   * This function is reference counted and can safely be called multiple times as long as there
   * are corresponding calls to {@link EntityCollection#resumeEvents}.
   *
   * @exception {DeveloperError} resumeEvents can not be called before suspendEvents.
   */
  CompositeEntityCollection.prototype.resumeEvents = function () {
    //>>includeStart('debug', pragmas.debug);
    if (this._suspendCount === 0) {
      throw new DeveloperError(
        "resumeEvents can not be called before suspendEvents."
      );
    }
    //>>includeEnd('debug');

    this._suspendCount--;
    // recomposite before triggering events (but only if required for performance) that might depend on a composited collection
    if (this._shouldRecomposite && this._suspendCount === 0) {
      recomposite(this);
      this._shouldRecomposite = false;
    }

    this._composite.resumeEvents();
  };

  /**
   * Computes the maximum availability of the entities in the collection.
   * If the collection contains a mix of infinitely available data and non-infinite data,
   * It will return the interval pertaining to the non-infinite data only.  If all
   * data is infinite, an infinite interval will be returned.
   *
   * @returns {TimeInterval} The availability of entities in the collection.
   */
  CompositeEntityCollection.prototype.computeAvailability = function () {
    return this._composite.computeAvailability();
  };

  /**
   * Gets an entity with the specified id.
   *
   * @param {String} id The id of the entity to retrieve.
   * @returns {Entity|undefined} The entity with the provided id or undefined if the id did not exist in the collection.
   */
  CompositeEntityCollection.prototype.getById = function (id) {
    return this._composite.getById(id);
  };

  CompositeEntityCollection.prototype._onCollectionChanged = function (
    collection,
    added,
    removed
  ) {
    var collections = this._collectionsCopy;
    var collectionsLength = collections.length;
    var composite = this._composite;
    composite.suspendEvents();

    var i;
    var q;
    var entity;
    var compositeEntity;
    var removedLength = removed.length;
    var eventHash = this._eventHash;
    var collectionId = collection.id;
    for (i = 0; i < removedLength; i++) {
      var removedEntity = removed[i];
      unsubscribeFromEntity(this, eventHash, collectionId, removedEntity);

      var removedId = removedEntity.id;
      //Check if the removed entity exists in any of the remaining collections
      //If so, we clean and remerge it.
      for (q = collectionsLength - 1; q >= 0; q--) {
        entity = collections[q].getById(removedId);
        if (defined(entity)) {
          if (!defined(compositeEntity)) {
            compositeEntity = composite.getById(removedId);
            clean(compositeEntity);
          }
          compositeEntity.merge(entity);
        }
      }
      //We never retrieved the compositeEntity, which means it no longer
      //exists in any of the collections, remove it from the composite.
      if (!defined(compositeEntity)) {
        composite.removeById(removedId);
      }
      compositeEntity = undefined;
    }

    var addedLength = added.length;
    for (i = 0; i < addedLength; i++) {
      var addedEntity = added[i];
      subscribeToEntity(this, eventHash, collectionId, addedEntity);

      var addedId = addedEntity.id;
      //We know the added entity exists in at least one collection,
      //but we need to check all collections and re-merge in order
      //to maintain the priority of properties.
      for (q = collectionsLength - 1; q >= 0; q--) {
        entity = collections[q].getById(addedId);
        if (defined(entity)) {
          if (!defined(compositeEntity)) {
            compositeEntity = composite.getById(addedId);
            if (!defined(compositeEntity)) {
              entityOptionsScratch$1.id = addedId;
              compositeEntity = new Entity(entityOptionsScratch$1);
              composite.add(compositeEntity);
            } else {
              clean(compositeEntity);
            }
          }
          compositeEntity.merge(entity);
        }
      }
      compositeEntity = undefined;
    }

    composite.resumeEvents();
  };

  CompositeEntityCollection.prototype._onDefinitionChanged = function (
    entity,
    propertyName,
    newValue,
    oldValue
  ) {
    var collections = this._collections;
    var composite = this._composite;

    var collectionsLength = collections.length;
    var id = entity.id;
    var compositeEntity = composite.getById(id);
    var compositeProperty = compositeEntity[propertyName];
    var newProperty = !defined(compositeProperty);

    var firstTime = true;
    for (var q = collectionsLength - 1; q >= 0; q--) {
      var innerEntity = collections[q].getById(entity.id);
      if (defined(innerEntity)) {
        var property = innerEntity[propertyName];
        if (defined(property)) {
          if (firstTime) {
            firstTime = false;
            //We only want to clone if the property is also mergeable.
            //This ensures that leaf properties are referenced and not copied,
            //which is the entire point of compositing.
            if (defined(property.merge) && defined(property.clone)) {
              compositeProperty = property.clone(compositeProperty);
            } else {
              compositeProperty = property;
              break;
            }
          }
          compositeProperty.merge(property);
        }
      }
    }

    if (
      newProperty &&
      compositeEntity.propertyNames.indexOf(propertyName) === -1
    ) {
      compositeEntity.addProperty(propertyName);
    }

    compositeEntity[propertyName] = compositeProperty;
  };

  function subscribeAll(property, eventHelper, definitionChanged, intervals) {
    function callback() {
      definitionChanged.raiseEvent(property);
    }
    var items = [];
    eventHelper.removeAll();
    var length = intervals.length;
    for (var i = 0; i < length; i++) {
      var interval = intervals.get(i);
      if (defined(interval.data) && items.indexOf(interval.data) === -1) {
        eventHelper.add(interval.data.definitionChanged, callback);
      }
    }
  }

  /**
   * A {@link Property} which is defined by a {@link TimeIntervalCollection}, where the
   * data property of each {@link TimeInterval} is another Property instance which is
   * evaluated at the provided time.
   *
   * @alias CompositeProperty
   * @constructor
   *
   *
   * @example
   * var constantProperty = ...;
   * var sampledProperty = ...;
   *
   * //Create a composite property from two previously defined properties
   * //where the property is valid on August 1st, 2012 and uses a constant
   * //property for the first half of the day and a sampled property for the
   * //remaining half.
   * var composite = new Cesium.CompositeProperty();
   * composite.intervals.addInterval(Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2012-08-01T00:00:00.00Z/2012-08-01T12:00:00.00Z',
   *     data : constantProperty
   * }));
   * composite.intervals.addInterval(Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2012-08-01T12:00:00.00Z/2012-08-02T00:00:00.00Z',
   *     isStartIncluded : false,
   *     isStopIncluded : false,
   *     data : sampledProperty
   * }));
   *
   * @see CompositeMaterialProperty
   * @see CompositePositionProperty
   */
  function CompositeProperty() {
    this._eventHelper = new EventHelper();
    this._definitionChanged = new Event();
    this._intervals = new TimeIntervalCollection();
    this._intervals.changedEvent.addEventListener(
      CompositeProperty.prototype._intervalsChanged,
      this
    );
  }

  Object.defineProperties(CompositeProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof CompositeProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._intervals.isEmpty;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value.
     * @memberof CompositeProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the interval collection.
     * @memberof CompositeProperty.prototype
     *
     * @type {TimeIntervalCollection}
     */
    intervals: {
      get: function () {
        return this._intervals;
      },
    },
  });

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  CompositeProperty.prototype.getValue = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required");
    }
    //>>includeEnd('debug');

    var innerProperty = this._intervals.findDataForIntervalContainingDate(time);
    if (defined(innerProperty)) {
      return innerProperty.getValue(time, result);
    }
    return undefined;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  CompositeProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof CompositeProperty && //
        this._intervals.equals(other._intervals, Property.equals))
    );
  };

  /**
   * @private
   */
  CompositeProperty.prototype._intervalsChanged = function () {
    subscribeAll(
      this,
      this._eventHelper,
      this._definitionChanged,
      this._intervals
    );
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * A {@link CompositeProperty} which is also a {@link MaterialProperty}.
   *
   * @alias CompositeMaterialProperty
   * @constructor
   */
  function CompositeMaterialProperty() {
    this._definitionChanged = new Event();
    this._composite = new CompositeProperty();
    this._composite.definitionChanged.addEventListener(
      CompositeMaterialProperty.prototype._raiseDefinitionChanged,
      this
    );
  }

  Object.defineProperties(CompositeMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof CompositeMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._composite.isConstant;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value.
     * @memberof CompositeMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the interval collection.
     * @memberof CompositeMaterialProperty.prototype
     *
     * @type {TimeIntervalCollection}
     */
    intervals: {
      get: function () {
        return this._composite._intervals;
      },
    },
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  CompositeMaterialProperty.prototype.getType = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required");
    }
    //>>includeEnd('debug');

    var innerProperty = this._composite._intervals.findDataForIntervalContainingDate(
      time
    );
    if (defined(innerProperty)) {
      return innerProperty.getType(time);
    }
    return undefined;
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  CompositeMaterialProperty.prototype.getValue = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required");
    }
    //>>includeEnd('debug');

    var innerProperty = this._composite._intervals.findDataForIntervalContainingDate(
      time
    );
    if (defined(innerProperty)) {
      return innerProperty.getValue(time, result);
    }
    return undefined;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  CompositeMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof CompositeMaterialProperty && //
        this._composite.equals(other._composite, Property.equals))
    );
  };

  /**
   * @private
   */
  CompositeMaterialProperty.prototype._raiseDefinitionChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * A {@link CompositeProperty} which is also a {@link PositionProperty}.
   *
   * @alias CompositePositionProperty
   * @constructor
   *
   * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
   */
  function CompositePositionProperty(referenceFrame) {
    this._referenceFrame = defaultValue(referenceFrame, ReferenceFrame$1.FIXED);
    this._definitionChanged = new Event();
    this._composite = new CompositeProperty();
    this._composite.definitionChanged.addEventListener(
      CompositePositionProperty.prototype._raiseDefinitionChanged,
      this
    );
  }

  Object.defineProperties(CompositePositionProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof CompositePositionProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._composite.isConstant;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value.
     * @memberof CompositePositionProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the interval collection.
     * @memberof CompositePositionProperty.prototype
     *
     * @type {TimeIntervalCollection}
     */
    intervals: {
      get: function () {
        return this._composite.intervals;
      },
    },
    /**
     * Gets or sets the reference frame which this position presents itself as.
     * Each PositionProperty making up this object has it's own reference frame,
     * so this property merely exposes a "preferred" reference frame for clients
     * to use.
     * @memberof CompositePositionProperty.prototype
     *
     * @type {ReferenceFrame}
     */
    referenceFrame: {
      get: function () {
        return this._referenceFrame;
      },
      set: function (value) {
        this._referenceFrame = value;
      },
    },
  });

  /**
   * Gets the value of the property at the provided time in the fixed frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  CompositePositionProperty.prototype.getValue = function (time, result) {
    return this.getValueInReferenceFrame(time, ReferenceFrame$1.FIXED, result);
  };

  /**
   * Gets the value of the property at the provided time and in the provided reference frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  CompositePositionProperty.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    if (!defined(referenceFrame)) {
      throw new DeveloperError("referenceFrame is required.");
    }
    //>>includeEnd('debug');

    var innerProperty = this._composite._intervals.findDataForIntervalContainingDate(
      time
    );
    if (defined(innerProperty)) {
      return innerProperty.getValueInReferenceFrame(time, referenceFrame, result);
    }
    return undefined;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  CompositePositionProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof CompositePositionProperty && //
      this._referenceFrame === other._referenceFrame && //
        this._composite.equals(other._composite, Property.equals))
    );
  };

  /**
   * @private
   */
  CompositePositionProperty.prototype._raiseDefinitionChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  var defaultZIndex = new ConstantProperty(0);

  /**
   * An abstract class for updating ground geometry entities.
   * @constructor
   * @alias GroundGeometryUpdater
   * @param {Object} options An object with the following properties:
   * @param {Entity} options.entity The entity containing the geometry to be visualized.
   * @param {Scene} options.scene The scene where visualization is taking place.
   * @param {Object} options.geometryOptions Options for the geometry
   * @param {String} options.geometryPropertyName The geometry property name
   * @param {String[]} options.observedPropertyNames The entity properties this geometry cares about
   */
  function GroundGeometryUpdater(options) {
    GeometryUpdater.call(this, options);

    this._zIndex = 0;
    this._terrainOffsetProperty = undefined;
  }

  if (defined(Object.create)) {
    GroundGeometryUpdater.prototype = Object.create(GeometryUpdater.prototype);
    GroundGeometryUpdater.prototype.constructor = GroundGeometryUpdater;
  }

  Object.defineProperties(GroundGeometryUpdater.prototype, {
    /**
     * Gets the zindex
     * @type {Number}
     * @memberof GroundGeometryUpdater.prototype
     * @readonly
     */
    zIndex: {
      get: function () {
        return this._zIndex;
      },
    },

    /**
     * Gets the terrain offset property
     * @type {TerrainOffsetProperty}
     * @memberof GroundGeometryUpdater.prototype
     * @readonly
     * @private
     */
    terrainOffsetProperty: {
      get: function () {
        return this._terrainOffsetProperty;
      },
    },
  });

  GroundGeometryUpdater.prototype._isOnTerrain = function (entity, geometry) {
    return (
      this._fillEnabled &&
      !defined(geometry.height) &&
      !defined(geometry.extrudedHeight) &&
      GroundPrimitive.isSupported(this._scene)
    );
  };

  GroundGeometryUpdater.prototype._getIsClosed = function (options) {
    var height = options.height;
    var extrudedHeight = options.extrudedHeight;
    return height === 0 || (defined(extrudedHeight) && extrudedHeight !== height);
  };

  GroundGeometryUpdater.prototype._computeCenter =
    DeveloperError.throwInstantiationError;

  GroundGeometryUpdater.prototype._onEntityPropertyChanged = function (
    entity,
    propertyName,
    newValue,
    oldValue
  ) {
    GeometryUpdater.prototype._onEntityPropertyChanged.call(
      this,
      entity,
      propertyName,
      newValue,
      oldValue
    );
    if (this._observedPropertyNames.indexOf(propertyName) === -1) {
      return;
    }

    var geometry = this._entity[this._geometryPropertyName];
    if (!defined(geometry)) {
      return;
    }
    if (
      defined(geometry.zIndex) &&
      (defined(geometry.height) || defined(geometry.extrudedHeight))
    ) {
      oneTimeWarning(oneTimeWarning.geometryZIndex);
    }

    this._zIndex = defaultValue(geometry.zIndex, defaultZIndex);

    if (defined(this._terrainOffsetProperty)) {
      this._terrainOffsetProperty.destroy();
      this._terrainOffsetProperty = undefined;
    }

    var heightReferenceProperty = geometry.heightReference;
    var extrudedHeightReferenceProperty = geometry.extrudedHeightReference;

    if (
      defined(heightReferenceProperty) ||
      defined(extrudedHeightReferenceProperty)
    ) {
      var centerPosition = new CallbackProperty(
        this._computeCenter.bind(this),
        !this._dynamic
      );
      this._terrainOffsetProperty = new TerrainOffsetProperty(
        this._scene,
        centerPosition,
        heightReferenceProperty,
        extrudedHeightReferenceProperty
      );
    }
  };

  /**
   * Destroys and resources used by the object.  Once an object is destroyed, it should not be used.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  GroundGeometryUpdater.prototype.destroy = function () {
    if (defined(this._terrainOffsetProperty)) {
      this._terrainOffsetProperty.destroy();
      this._terrainOffsetProperty = undefined;
    }

    GeometryUpdater.prototype.destroy.call(this);
  };

  /**
   * @private
   */
  GroundGeometryUpdater.getGeometryHeight = function (height, heightReference) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("heightReference", heightReference);
    //>>includeEnd('debug');
    if (!defined(height)) {
      if (heightReference !== HeightReference$1.NONE) {
        oneTimeWarning(oneTimeWarning.geometryHeightReference);
      }
      return;
    }

    if (heightReference !== HeightReference$1.CLAMP_TO_GROUND) {
      return height;
    }
    return 0.0;
  };

  /**
   * @private
   */
  GroundGeometryUpdater.getGeometryExtrudedHeight = function (
    extrudedHeight,
    extrudedHeightReference
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("extrudedHeightReference", extrudedHeightReference);
    //>>includeEnd('debug');
    if (!defined(extrudedHeight)) {
      if (extrudedHeightReference !== HeightReference$1.NONE) {
        oneTimeWarning(oneTimeWarning.geometryExtrudedHeightReference);
      }
      return;
    }
    if (extrudedHeightReference !== HeightReference$1.CLAMP_TO_GROUND) {
      return extrudedHeight;
    }

    return GroundGeometryUpdater.CLAMP_TO_GROUND;
  };

  /**
   * @private
   */
  GroundGeometryUpdater.CLAMP_TO_GROUND = "clamp";

  /**
   * @private
   */
  GroundGeometryUpdater.computeGeometryOffsetAttribute = function (
    height,
    heightReference,
    extrudedHeight,
    extrudedHeightReference
  ) {
    if (!defined(height) || !defined(heightReference)) {
      heightReference = HeightReference$1.NONE;
    }
    if (!defined(extrudedHeight) || !defined(extrudedHeightReference)) {
      extrudedHeightReference = HeightReference$1.NONE;
    }
    var n = 0;
    if (heightReference !== HeightReference$1.NONE) {
      n++;
    }
    if (extrudedHeightReference === HeightReference$1.RELATIVE_TO_GROUND) {
      n++;
    }
    if (n === 2) {
      return GeometryOffsetAttribute$1.ALL;
    }
    if (n === 1) {
      return GeometryOffsetAttribute$1.TOP;
    }

    return undefined;
  };

  var scratchColor$9 = new Color();
  var defaultOffset$1 = Cartesian3.ZERO;
  var offsetScratch$4 = new Cartesian3();
  var scratchRectangle$3 = new Rectangle();

  function CorridorGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.positions = undefined;
    this.width = undefined;
    this.cornerType = undefined;
    this.height = undefined;
    this.extrudedHeight = undefined;
    this.granularity = undefined;
    this.offsetAttribute = undefined;
  }

  /**
   * A {@link GeometryUpdater} for corridors.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias CorridorGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function CorridorGeometryUpdater(entity, scene) {
    GroundGeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new CorridorGeometryOptions(entity),
      geometryPropertyName: "corridor",
      observedPropertyNames: ["availability", "corridor"],
    });

    this._onEntityPropertyChanged(entity, "corridor", entity.corridor, undefined);
  }

  if (defined(Object.create)) {
    CorridorGeometryUpdater.prototype = Object.create(
      GroundGeometryUpdater.prototype
    );
    CorridorGeometryUpdater.prototype.constructor = CorridorGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  CorridorGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._fillProperty.getValue(time)
      ),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        this._distanceDisplayConditionProperty.getValue(time)
      ),
      offset: undefined,
      color: undefined,
    };

    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$9);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }

    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$1,
          offsetScratch$4
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new CorridorGeometry(this._options),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  CorridorGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$9
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        this._distanceDisplayConditionProperty.getValue(time)
      ),
      offset: undefined,
    };

    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$1,
          offsetScratch$4
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new CorridorOutlineGeometry(this._options),
      attributes: attributes,
    });
  };

  CorridorGeometryUpdater.prototype._computeCenter = function (time, result) {
    var positions = Property.getValueOrUndefined(
      this._entity.corridor.positions,
      time
    );
    if (!defined(positions) || positions.length === 0) {
      return;
    }
    return Cartesian3.clone(
      positions[Math.floor(positions.length / 2.0)],
      result
    );
  };

  CorridorGeometryUpdater.prototype._isHidden = function (entity, corridor) {
    return (
      !defined(corridor.positions) ||
      !defined(corridor.width) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, corridor)
    );
  };

  CorridorGeometryUpdater.prototype._isDynamic = function (entity, corridor) {
    return (
      !corridor.positions.isConstant || //
      !Property.isConstant(corridor.height) || //
      !Property.isConstant(corridor.extrudedHeight) || //
      !Property.isConstant(corridor.granularity) || //
      !Property.isConstant(corridor.width) || //
      !Property.isConstant(corridor.outlineWidth) || //
      !Property.isConstant(corridor.cornerType) || //
      !Property.isConstant(corridor.zIndex) || //
      (this._onTerrain &&
        !Property.isConstant(this._materialProperty) &&
        !(this._materialProperty instanceof ColorMaterialProperty))
    );
  };

  CorridorGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    corridor
  ) {
    var heightValue = Property.getValueOrUndefined(
      corridor.height,
      Iso8601.MINIMUM_VALUE
    );
    var heightReferenceValue = Property.getValueOrDefault(
      corridor.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      corridor.extrudedHeight,
      Iso8601.MINIMUM_VALUE
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      corridor.extrudedHeightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    if (defined(extrudedHeightValue) && !defined(heightValue)) {
      heightValue = 0;
    }

    var options = this._options;
    options.vertexFormat =
      this._materialProperty instanceof ColorMaterialProperty
        ? PerInstanceColorAppearance.VERTEX_FORMAT
        : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.positions = corridor.positions.getValue(
      Iso8601.MINIMUM_VALUE,
      options.positions
    );
    options.width = corridor.width.getValue(Iso8601.MINIMUM_VALUE);
    options.granularity = Property.getValueOrUndefined(
      corridor.granularity,
      Iso8601.MINIMUM_VALUE
    );
    options.cornerType = Property.getValueOrUndefined(
      corridor.cornerType,
      Iso8601.MINIMUM_VALUE
    );
    options.offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
      heightValue,
      heightReferenceValue,
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    options.height = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        CorridorGeometry.computeRectangle(options, scratchRectangle$3)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  CorridorGeometryUpdater.DynamicGeometryUpdater = DynamicCorridorGeometryUpdater;

  /**
   * @private
   */
  function DynamicCorridorGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicCorridorGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicCorridorGeometryUpdater.prototype.constructor = DynamicCorridorGeometryUpdater;
  }

  DynamicCorridorGeometryUpdater.prototype._isHidden = function (
    entity,
    corridor,
    time
  ) {
    var options = this._options;
    return (
      !defined(options.positions) ||
      !defined(options.width) ||
      DynamicGeometryUpdater.prototype._isHidden.call(
        this,
        entity,
        corridor,
        time
      )
    );
  };

  DynamicCorridorGeometryUpdater.prototype._setOptions = function (
    entity,
    corridor,
    time
  ) {
    var options = this._options;
    var heightValue = Property.getValueOrUndefined(corridor.height, time);
    var heightReferenceValue = Property.getValueOrDefault(
      corridor.heightReference,
      time,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      corridor.extrudedHeight,
      time
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      corridor.extrudedHeightReference,
      time,
      HeightReference$1.NONE
    );
    if (defined(extrudedHeightValue) && !defined(heightValue)) {
      heightValue = 0;
    }

    options.positions = Property.getValueOrUndefined(corridor.positions, time);
    options.width = Property.getValueOrUndefined(corridor.width, time);
    options.granularity = Property.getValueOrUndefined(
      corridor.granularity,
      time
    );
    options.cornerType = Property.getValueOrUndefined(corridor.cornerType, time);
    options.offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
      heightValue,
      heightReferenceValue,
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    options.height = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        CorridorGeometry.computeRectangle(options, scratchRectangle$3)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  /**
   * Defines the interface for data sources, which turn arbitrary data into a
   * {@link EntityCollection} for generic consumption. This object is an interface
   * for documentation purposes and is not intended to be instantiated directly.
   * @alias DataSource
   * @constructor
   *
   * @see Entity
   * @see DataSourceDisplay
   */
  function DataSource() {
    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(DataSource.prototype, {
    /**
     * Gets a human-readable name for this instance.
     * @memberof DataSource.prototype
     * @type {String}
     */
    name: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets the preferred clock settings for this data source.
     * @memberof DataSource.prototype
     * @type {DataSourceClock}
     */
    clock: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets the collection of {@link Entity} instances.
     * @memberof DataSource.prototype
     * @type {EntityCollection}
     */
    entities: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets a value indicating if the data source is currently loading data.
     * @memberof DataSource.prototype
     * @type {Boolean}
     */
    isLoading: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets an event that will be raised when the underlying data changes.
     * @memberof DataSource.prototype
     * @type {Event}
     */
    changedEvent: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets an event that will be raised if an error is encountered during processing.
     * @memberof DataSource.prototype
     * @type {Event}
     */
    errorEvent: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets an event that will be raised when the value of isLoading changes.
     * @memberof DataSource.prototype
     * @type {Event}
     */
    loadingEvent: {
      get: DeveloperError.throwInstantiationError,
    },
    /**
     * Gets whether or not this data source should be displayed.
     * @memberof DataSource.prototype
     * @type {Boolean}
     */
    show: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets or sets the clustering options for this data source. This object can be shared between multiple data sources.
     *
     * @memberof DataSource.prototype
     * @type {EntityCluster}
     */
    clustering: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Updates the data source to the provided time.  This function is optional and
   * is not required to be implemented.  It is provided for data sources which
   * retrieve data based on the current animation time or scene state.
   * If implemented, update will be called by {@link DataSourceDisplay} once a frame.
   *
   * @param {JulianDate} time The simulation time.
   * @returns {Boolean} True if this data source is ready to be displayed at the provided time, false otherwise.
   */
  DataSource.prototype.update = function (time) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * @private
   */
  DataSource.setLoading = function (dataSource, isLoading) {
    if (dataSource._isLoading !== isLoading) {
      if (isLoading) {
        dataSource._entityCollection.suspendEvents();
      } else {
        dataSource._entityCollection.resumeEvents();
      }
      dataSource._isLoading = isLoading;
      dataSource._loading.raiseEvent(dataSource, isLoading);
    }
  };

  /**
   * A graphical point positioned in the 3D scene, that is created
   * and rendered using a {@link PointPrimitiveCollection}.  A point is created and its initial
   * properties are set by calling {@link PointPrimitiveCollection#add}.
   *
   * @alias PointPrimitive
   *
   * @performance Reading a property, e.g., {@link PointPrimitive#show}, is constant time.
   * Assigning to a property is constant time but results in
   * CPU to GPU traffic when {@link PointPrimitiveCollection#update} is called.  The per-pointPrimitive traffic is
   * the same regardless of how many properties were updated.  If most pointPrimitives in a collection need to be
   * updated, it may be more efficient to clear the collection with {@link PointPrimitiveCollection#removeAll}
   * and add new pointPrimitives instead of modifying each one.
   *
   * @exception {DeveloperError} scaleByDistance.far must be greater than scaleByDistance.near
   * @exception {DeveloperError} translucencyByDistance.far must be greater than translucencyByDistance.near
   * @exception {DeveloperError} distanceDisplayCondition.far must be greater than distanceDisplayCondition.near
   *
   * @see PointPrimitiveCollection
   * @see PointPrimitiveCollection#add
   *
   * @internalConstructor
   * @class
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Points.html|Cesium Sandcastle Points Demo}
   */
  function PointPrimitive(options, pointPrimitiveCollection) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (
      defined(options.disableDepthTestDistance) &&
      options.disableDepthTestDistance < 0.0
    ) {
      throw new DeveloperError(
        "disableDepthTestDistance must be greater than or equal to 0.0."
      );
    }
    //>>includeEnd('debug');

    var translucencyByDistance = options.translucencyByDistance;
    var scaleByDistance = options.scaleByDistance;
    var distanceDisplayCondition = options.distanceDisplayCondition;
    if (defined(translucencyByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (translucencyByDistance.far <= translucencyByDistance.near) {
        throw new DeveloperError(
          "translucencyByDistance.far must be greater than translucencyByDistance.near."
        );
      }
      //>>includeEnd('debug');
      translucencyByDistance = NearFarScalar.clone(translucencyByDistance);
    }
    if (defined(scaleByDistance)) {
      //>>includeStart('debug', pragmas.debug);
      if (scaleByDistance.far <= scaleByDistance.near) {
        throw new DeveloperError(
          "scaleByDistance.far must be greater than scaleByDistance.near."
        );
      }
      //>>includeEnd('debug');
      scaleByDistance = NearFarScalar.clone(scaleByDistance);
    }
    if (defined(distanceDisplayCondition)) {
      //>>includeStart('debug', pragmas.debug);
      if (distanceDisplayCondition.far <= distanceDisplayCondition.near) {
        throw new DeveloperError(
          "distanceDisplayCondition.far must be greater than distanceDisplayCondition.near."
        );
      }
      //>>includeEnd('debug');
      distanceDisplayCondition = DistanceDisplayCondition.clone(
        distanceDisplayCondition
      );
    }

    this._show = defaultValue(options.show, true);
    this._position = Cartesian3.clone(
      defaultValue(options.position, Cartesian3.ZERO)
    );
    this._actualPosition = Cartesian3.clone(this._position); // For columbus view and 2D
    this._color = Color.clone(defaultValue(options.color, Color.WHITE));
    this._outlineColor = Color.clone(
      defaultValue(options.outlineColor, Color.TRANSPARENT)
    );
    this._outlineWidth = defaultValue(options.outlineWidth, 0.0);
    this._pixelSize = defaultValue(options.pixelSize, 10.0);
    this._scaleByDistance = scaleByDistance;
    this._translucencyByDistance = translucencyByDistance;
    this._distanceDisplayCondition = distanceDisplayCondition;
    this._disableDepthTestDistance = defaultValue(
      options.disableDepthTestDistance,
      0.0
    );
    this._id = options.id;
    this._collection = defaultValue(options.collection, pointPrimitiveCollection);

    this._clusterShow = true;

    this._pickId = undefined;
    this._pointPrimitiveCollection = pointPrimitiveCollection;
    this._dirty = false;
    this._index = -1; //Used only by PointPrimitiveCollection
  }

  var SHOW_INDEX$4 = (PointPrimitive.SHOW_INDEX = 0);
  var POSITION_INDEX$4 = (PointPrimitive.POSITION_INDEX = 1);
  var COLOR_INDEX$2 = (PointPrimitive.COLOR_INDEX = 2);
  var OUTLINE_COLOR_INDEX = (PointPrimitive.OUTLINE_COLOR_INDEX = 3);
  var OUTLINE_WIDTH_INDEX = (PointPrimitive.OUTLINE_WIDTH_INDEX = 4);
  var PIXEL_SIZE_INDEX = (PointPrimitive.PIXEL_SIZE_INDEX = 5);
  var SCALE_BY_DISTANCE_INDEX$2 = (PointPrimitive.SCALE_BY_DISTANCE_INDEX = 6);
  var TRANSLUCENCY_BY_DISTANCE_INDEX$2 = (PointPrimitive.TRANSLUCENCY_BY_DISTANCE_INDEX = 7);
  var DISTANCE_DISPLAY_CONDITION_INDEX$1 = (PointPrimitive.DISTANCE_DISPLAY_CONDITION_INDEX = 8);
  var DISABLE_DEPTH_DISTANCE_INDEX = (PointPrimitive.DISABLE_DEPTH_DISTANCE_INDEX = 9);
  PointPrimitive.NUMBER_OF_PROPERTIES = 10;

  function makeDirty$2(pointPrimitive, propertyChanged) {
    var pointPrimitiveCollection = pointPrimitive._pointPrimitiveCollection;
    if (defined(pointPrimitiveCollection)) {
      pointPrimitiveCollection._updatePointPrimitive(
        pointPrimitive,
        propertyChanged
      );
      pointPrimitive._dirty = true;
    }
  }

  Object.defineProperties(PointPrimitive.prototype, {
    /**
     * Determines if this point will be shown.  Use this to hide or show a point, instead
     * of removing it and re-adding it to the collection.
     * @memberof PointPrimitive.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._show;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._show !== value) {
          this._show = value;
          makeDirty$2(this, SHOW_INDEX$4);
        }
      },
    },

    /**
     * Gets or sets the Cartesian position of this point.
     * @memberof PointPrimitive.prototype
     * @type {Cartesian3}
     */
    position: {
      get: function () {
        return this._position;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug)
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var position = this._position;
        if (!Cartesian3.equals(position, value)) {
          Cartesian3.clone(value, position);
          Cartesian3.clone(value, this._actualPosition);

          makeDirty$2(this, POSITION_INDEX$4);
        }
      },
    },

    /**
     * Gets or sets near and far scaling properties of a point based on the point's distance from the camera.
     * A point's scale will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the point's scale remains clamped to the nearest bound.  This scale
     * multiplies the pixelSize and outlineWidth to affect the total size of the point.  If undefined,
     * scaleByDistance will be disabled.
     * @memberof PointPrimitive.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a pointPrimitive's scaleByDistance to scale to 15 when the
     * // camera is 1500 meters from the pointPrimitive and disappear as
     * // the camera distance approaches 8.0e6 meters.
     * p.scaleByDistance = new Cesium.NearFarScalar(1.5e2, 15, 8.0e6, 0.0);
     *
     * @example
     * // Example 2.
     * // disable scaling by distance
     * p.scaleByDistance = undefined;
     */
    scaleByDistance: {
      get: function () {
        return this._scaleByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var scaleByDistance = this._scaleByDistance;
        if (!NearFarScalar.equals(scaleByDistance, value)) {
          this._scaleByDistance = NearFarScalar.clone(value, scaleByDistance);
          makeDirty$2(this, SCALE_BY_DISTANCE_INDEX$2);
        }
      },
    },

    /**
     * Gets or sets near and far translucency properties of a point based on the point's distance from the camera.
     * A point's translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the point's translucency remains clamped to the nearest bound.  If undefined,
     * translucencyByDistance will be disabled.
     * @memberof PointPrimitive.prototype
     * @type {NearFarScalar}
     *
     * @example
     * // Example 1.
     * // Set a point's translucency to 1.0 when the
     * // camera is 1500 meters from the point and disappear as
     * // the camera distance approaches 8.0e6 meters.
     * p.translucencyByDistance = new Cesium.NearFarScalar(1.5e2, 1.0, 8.0e6, 0.0);
     *
     * @example
     * // Example 2.
     * // disable translucency by distance
     * p.translucencyByDistance = undefined;
     */
    translucencyByDistance: {
      get: function () {
        return this._translucencyByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');

        var translucencyByDistance = this._translucencyByDistance;
        if (!NearFarScalar.equals(translucencyByDistance, value)) {
          this._translucencyByDistance = NearFarScalar.clone(
            value,
            translucencyByDistance
          );
          makeDirty$2(this, TRANSLUCENCY_BY_DISTANCE_INDEX$2);
        }
      },
    },

    /**
     * Gets or sets the inner size of the point in pixels.
     * @memberof PointPrimitive.prototype
     * @type {Number}
     */
    pixelSize: {
      get: function () {
        return this._pixelSize;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._pixelSize !== value) {
          this._pixelSize = value;
          makeDirty$2(this, PIXEL_SIZE_INDEX);
        }
      },
    },

    /**
     * Gets or sets the inner color of the point.
     * The red, green, blue, and alpha values are indicated by <code>value</code>'s <code>red</code>, <code>green</code>,
     * <code>blue</code>, and <code>alpha</code> properties as shown in Example 1.  These components range from <code>0.0</code>
     * (no intensity) to <code>1.0</code> (full intensity).
     * @memberof PointPrimitive.prototype
     * @type {Color}
     *
     * @example
     * // Example 1. Assign yellow.
     * p.color = Cesium.Color.YELLOW;
     *
     * @example
     * // Example 2. Make a pointPrimitive 50% translucent.
     * p.color = new Cesium.Color(1.0, 1.0, 1.0, 0.5);
     */
    color: {
      get: function () {
        return this._color;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var color = this._color;
        if (!Color.equals(color, value)) {
          Color.clone(value, color);
          makeDirty$2(this, COLOR_INDEX$2);
        }
      },
    },

    /**
     * Gets or sets the outline color of the point.
     * @memberof PointPrimitive.prototype
     * @type {Color}
     */
    outlineColor: {
      get: function () {
        return this._outlineColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        var outlineColor = this._outlineColor;
        if (!Color.equals(outlineColor, value)) {
          Color.clone(value, outlineColor);
          makeDirty$2(this, OUTLINE_COLOR_INDEX);
        }
      },
    },

    /**
     * Gets or sets the outline width in pixels.  This width adds to pixelSize,
     * increasing the total size of the point.
     * @memberof PointPrimitive.prototype
     * @type {Number}
     */
    outlineWidth: {
      get: function () {
        return this._outlineWidth;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._outlineWidth !== value) {
          this._outlineWidth = value;
          makeDirty$2(this, OUTLINE_WIDTH_INDEX);
        }
      },
    },

    /**
     * Gets or sets the condition specifying at what distance from the camera that this point will be displayed.
     * @memberof PointPrimitive.prototype
     * @type {DistanceDisplayCondition}
     * @default undefined
     */
    distanceDisplayCondition: {
      get: function () {
        return this._distanceDisplayCondition;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far <= value.near) {
          throw new DeveloperError("far must be greater than near");
        }
        //>>includeEnd('debug');
        if (
          !DistanceDisplayCondition.equals(this._distanceDisplayCondition, value)
        ) {
          this._distanceDisplayCondition = DistanceDisplayCondition.clone(
            value,
            this._distanceDisplayCondition
          );
          makeDirty$2(this, DISTANCE_DISPLAY_CONDITION_INDEX$1);
        }
      },
    },

    /**
     * Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
     * When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.
     * @memberof PointPrimitive.prototype
     * @type {Number}
     * @default 0.0
     */
    disableDepthTestDistance: {
      get: function () {
        return this._disableDepthTestDistance;
      },
      set: function (value) {
        if (this._disableDepthTestDistance !== value) {
          //>>includeStart('debug', pragmas.debug);
          if (!defined(value) || value < 0.0) {
            throw new DeveloperError(
              "disableDepthTestDistance must be greater than or equal to 0.0."
            );
          }
          //>>includeEnd('debug');
          this._disableDepthTestDistance = value;
          makeDirty$2(this, DISABLE_DEPTH_DISTANCE_INDEX);
        }
      },
    },

    /**
     * Gets or sets the user-defined value returned when the point is picked.
     * @memberof PointPrimitive.prototype
     * @type {*}
     */
    id: {
      get: function () {
        return this._id;
      },
      set: function (value) {
        this._id = value;
        if (defined(this._pickId)) {
          this._pickId.object.id = value;
        }
      },
    },

    /**
     * @private
     */
    pickId: {
      get: function () {
        return this._pickId;
      },
    },

    /**
     * Determines whether or not this point will be shown or hidden because it was clustered.
     * @memberof PointPrimitive.prototype
     * @type {Boolean}
     * @private
     */
    clusterShow: {
      get: function () {
        return this._clusterShow;
      },
      set: function (value) {
        if (this._clusterShow !== value) {
          this._clusterShow = value;
          makeDirty$2(this, SHOW_INDEX$4);
        }
      },
    },
  });

  PointPrimitive.prototype.getPickId = function (context) {
    if (!defined(this._pickId)) {
      this._pickId = context.createPickId({
        primitive: this,
        collection: this._collection,
        id: this._id,
      });
    }

    return this._pickId;
  };

  PointPrimitive.prototype._getActualPosition = function () {
    return this._actualPosition;
  };

  PointPrimitive.prototype._setActualPosition = function (value) {
    Cartesian3.clone(value, this._actualPosition);
    makeDirty$2(this, POSITION_INDEX$4);
  };

  var tempCartesian3$1 = new Cartesian4();
  PointPrimitive._computeActualPosition = function (
    position,
    frameState,
    modelMatrix
  ) {
    if (frameState.mode === SceneMode$1.SCENE3D) {
      return position;
    }

    Matrix4.multiplyByPoint(modelMatrix, position, tempCartesian3$1);
    return SceneTransforms.computeActualWgs84Position(frameState, tempCartesian3$1);
  };

  var scratchCartesian4$4 = new Cartesian4();

  // This function is basically a stripped-down JavaScript version of PointPrimitiveCollectionVS.glsl
  PointPrimitive._computeScreenSpacePosition = function (
    modelMatrix,
    position,
    scene,
    result
  ) {
    // Model to world coordinates
    var positionWorld = Matrix4.multiplyByVector(
      modelMatrix,
      Cartesian4.fromElements(
        position.x,
        position.y,
        position.z,
        1,
        scratchCartesian4$4
      ),
      scratchCartesian4$4
    );
    var positionWC = SceneTransforms.wgs84ToWindowCoordinates(
      scene,
      positionWorld,
      result
    );
    return positionWC;
  };

  /**
   * Computes the screen-space position of the point's origin.
   * The screen space origin is the top, left corner of the canvas; <code>x</code> increases from
   * left to right, and <code>y</code> increases from top to bottom.
   *
   * @param {Scene} scene The scene.
   * @param {Cartesian2} [result] The object onto which to store the result.
   * @returns {Cartesian2} The screen-space position of the point.
   *
   * @exception {DeveloperError} PointPrimitive must be in a collection.
   *
   * @example
   * console.log(p.computeScreenSpacePosition(scene).toString());
   */
  PointPrimitive.prototype.computeScreenSpacePosition = function (scene, result) {
    var pointPrimitiveCollection = this._pointPrimitiveCollection;
    if (!defined(result)) {
      result = new Cartesian2();
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(pointPrimitiveCollection)) {
      throw new DeveloperError("PointPrimitive must be in a collection.");
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    var modelMatrix = pointPrimitiveCollection.modelMatrix;
    var windowCoordinates = PointPrimitive._computeScreenSpacePosition(
      modelMatrix,
      this._actualPosition,
      scene,
      result
    );
    if (!defined(windowCoordinates)) {
      return undefined;
    }

    windowCoordinates.y = scene.canvas.clientHeight - windowCoordinates.y;
    return windowCoordinates;
  };

  /**
   * Gets a point's screen space bounding box centered around screenSpacePosition.
   * @param {PointPrimitive} point The point to get the screen space bounding box for.
   * @param {Cartesian2} screenSpacePosition The screen space center of the label.
   * @param {BoundingRectangle} [result] The object onto which to store the result.
   * @returns {BoundingRectangle} The screen space bounding box.
   *
   * @private
   */
  PointPrimitive.getScreenSpaceBoundingBox = function (
    point,
    screenSpacePosition,
    result
  ) {
    var size = point.pixelSize;
    var halfSize = size * 0.5;

    var x = screenSpacePosition.x - halfSize;
    var y = screenSpacePosition.y - halfSize;
    var width = size;
    var height = size;

    if (!defined(result)) {
      result = new BoundingRectangle();
    }

    result.x = x;
    result.y = y;
    result.width = width;
    result.height = height;

    return result;
  };

  /**
   * Determines if this point equals another point.  Points are equal if all their properties
   * are equal.  Points in different collections can be equal.
   *
   * @param {PointPrimitive} other The point to compare for equality.
   * @returns {Boolean} <code>true</code> if the points are equal; otherwise, <code>false</code>.
   */
  PointPrimitive.prototype.equals = function (other) {
    return (
      this === other ||
      (defined(other) &&
        this._id === other._id &&
        Cartesian3.equals(this._position, other._position) &&
        Color.equals(this._color, other._color) &&
        this._pixelSize === other._pixelSize &&
        this._outlineWidth === other._outlineWidth &&
        this._show === other._show &&
        Color.equals(this._outlineColor, other._outlineColor) &&
        NearFarScalar.equals(this._scaleByDistance, other._scaleByDistance) &&
        NearFarScalar.equals(
          this._translucencyByDistance,
          other._translucencyByDistance
        ) &&
        DistanceDisplayCondition.equals(
          this._distanceDisplayCondition,
          other._distanceDisplayCondition
        ) &&
        this._disableDepthTestDistance === other._disableDepthTestDistance)
    );
  };

  PointPrimitive.prototype._destroy = function () {
    this._pickId = this._pickId && this._pickId.destroy();
    this._pointPrimitiveCollection = undefined;
  };

  //This file is automatically rebuilt by the Cesium build process.
  var PointPrimitiveCollectionFS = "varying vec4 v_color;\n\
varying vec4 v_outlineColor;\n\
varying float v_innerPercent;\n\
varying float v_pixelDistance;\n\
varying vec4 v_pickColor;\n\
void main()\n\
{\n\
float distanceToCenter = length(gl_PointCoord - vec2(0.5));\n\
float maxDistance = max(0.0, 0.5 - v_pixelDistance);\n\
float wholeAlpha = 1.0 - smoothstep(maxDistance, 0.5, distanceToCenter);\n\
float innerAlpha = 1.0 - smoothstep(maxDistance * v_innerPercent, 0.5 * v_innerPercent, distanceToCenter);\n\
vec4 color = mix(v_outlineColor, v_color, innerAlpha);\n\
color.a *= wholeAlpha;\n\
#if !defined(OPAQUE) && !defined(TRANSLUCENT)\n\
if (color.a < 0.005)\n\
{\n\
discard;\n\
}\n\
#else\n\
#ifdef OPAQUE\n\
if (color.a < 0.995)\n\
{\n\
discard;\n\
}\n\
#else\n\
if (color.a >= 0.995)\n\
{\n\
discard;\n\
}\n\
#endif\n\
#endif\n\
gl_FragColor = czm_gammaCorrect(color);\n\
czm_writeLogDepth();\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PointPrimitiveCollectionVS = "uniform float u_maxTotalPointSize;\n\
attribute vec4 positionHighAndSize;\n\
attribute vec4 positionLowAndOutline;\n\
attribute vec4 compressedAttribute0;\n\
attribute vec4 compressedAttribute1;\n\
attribute vec4 scaleByDistance;\n\
attribute vec3 distanceDisplayConditionAndDisableDepth;\n\
varying vec4 v_color;\n\
varying vec4 v_outlineColor;\n\
varying float v_innerPercent;\n\
varying float v_pixelDistance;\n\
varying vec4 v_pickColor;\n\
const float SHIFT_LEFT8 = 256.0;\n\
const float SHIFT_RIGHT8 = 1.0 / 256.0;\n\
void main()\n\
{\n\
vec3 positionHigh = positionHighAndSize.xyz;\n\
vec3 positionLow = positionLowAndOutline.xyz;\n\
float outlineWidthBothSides = 2.0 * positionLowAndOutline.w;\n\
float totalSize = positionHighAndSize.w + outlineWidthBothSides;\n\
float outlinePercent = outlineWidthBothSides / totalSize;\n\
totalSize *= czm_pixelRatio;\n\
totalSize += 3.0;\n\
float temp = compressedAttribute1.x * SHIFT_RIGHT8;\n\
float show = floor(temp);\n\
#ifdef EYE_DISTANCE_TRANSLUCENCY\n\
vec4 translucencyByDistance;\n\
translucencyByDistance.x = compressedAttribute1.z;\n\
translucencyByDistance.z = compressedAttribute1.w;\n\
translucencyByDistance.y = ((temp - floor(temp)) * SHIFT_LEFT8) / 255.0;\n\
temp = compressedAttribute1.y * SHIFT_RIGHT8;\n\
translucencyByDistance.w = ((temp - floor(temp)) * SHIFT_LEFT8) / 255.0;\n\
#endif\n\
vec4 color;\n\
vec4 outlineColor;\n\
vec4 pickColor;\n\
temp = compressedAttribute0.z * SHIFT_RIGHT8;\n\
pickColor.b = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
pickColor.g = (temp - floor(temp)) * SHIFT_LEFT8;\n\
pickColor.r = floor(temp);\n\
temp = compressedAttribute0.x * SHIFT_RIGHT8;\n\
color.b = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
color.g = (temp - floor(temp)) * SHIFT_LEFT8;\n\
color.r = floor(temp);\n\
temp = compressedAttribute0.y * SHIFT_RIGHT8;\n\
outlineColor.b = (temp - floor(temp)) * SHIFT_LEFT8;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
outlineColor.g = (temp - floor(temp)) * SHIFT_LEFT8;\n\
outlineColor.r = floor(temp);\n\
temp = compressedAttribute0.w * SHIFT_RIGHT8;\n\
pickColor.a = (temp - floor(temp)) * SHIFT_LEFT8;\n\
pickColor = pickColor / 255.0;\n\
temp = floor(temp) * SHIFT_RIGHT8;\n\
outlineColor.a = (temp - floor(temp)) * SHIFT_LEFT8;\n\
outlineColor /= 255.0;\n\
color.a = floor(temp);\n\
color /= 255.0;\n\
vec4 p = czm_translateRelativeToEye(positionHigh, positionLow);\n\
vec4 positionEC = czm_modelViewRelativeToEye * p;\n\
#if defined(EYE_DISTANCE_SCALING) || defined(EYE_DISTANCE_TRANSLUCENCY) || defined(DISTANCE_DISPLAY_CONDITION) || defined(DISABLE_DEPTH_DISTANCE)\n\
float lengthSq;\n\
if (czm_sceneMode == czm_sceneMode2D)\n\
{\n\
lengthSq = czm_eyeHeight2D.y;\n\
}\n\
else\n\
{\n\
lengthSq = dot(positionEC.xyz, positionEC.xyz);\n\
}\n\
#endif\n\
#ifdef EYE_DISTANCE_SCALING\n\
totalSize *= czm_nearFarScalar(scaleByDistance, lengthSq);\n\
#endif\n\
totalSize = min(totalSize, u_maxTotalPointSize);\n\
if (totalSize < 1.0)\n\
{\n\
positionEC.xyz = vec3(0.0);\n\
totalSize = 1.0;\n\
}\n\
float translucency = 1.0;\n\
#ifdef EYE_DISTANCE_TRANSLUCENCY\n\
translucency = czm_nearFarScalar(translucencyByDistance, lengthSq);\n\
if (translucency < 0.004)\n\
{\n\
positionEC.xyz = vec3(0.0);\n\
}\n\
#endif\n\
#ifdef DISTANCE_DISPLAY_CONDITION\n\
float nearSq = distanceDisplayConditionAndDisableDepth.x;\n\
float farSq = distanceDisplayConditionAndDisableDepth.y;\n\
if (lengthSq < nearSq || lengthSq > farSq) {\n\
positionEC.xyz = vec3(0.0, 0.0, 1.0);\n\
}\n\
#endif\n\
gl_Position = czm_projection * positionEC;\n\
czm_vertexLogDepth();\n\
#ifdef DISABLE_DEPTH_DISTANCE\n\
float disableDepthTestDistance = distanceDisplayConditionAndDisableDepth.z;\n\
if (disableDepthTestDistance == 0.0 && czm_minimumDisableDepthTestDistance != 0.0)\n\
{\n\
disableDepthTestDistance = czm_minimumDisableDepthTestDistance;\n\
}\n\
if (disableDepthTestDistance != 0.0)\n\
{\n\
float zclip = gl_Position.z / gl_Position.w;\n\
bool clipped = (zclip < -1.0 || zclip > 1.0);\n\
if (!clipped && (disableDepthTestDistance < 0.0 || (lengthSq > 0.0 && lengthSq < disableDepthTestDistance)))\n\
{\n\
gl_Position.z = -gl_Position.w;\n\
#ifdef LOG_DEPTH\n\
czm_vertexLogDepth(vec4(czm_currentFrustum.x));\n\
#endif\n\
}\n\
}\n\
#endif\n\
v_color = color;\n\
v_color.a *= translucency * show;\n\
v_outlineColor = outlineColor;\n\
v_outlineColor.a *= translucency * show;\n\
v_innerPercent = 1.0 - outlinePercent;\n\
v_pixelDistance = 2.0 / totalSize;\n\
gl_PointSize = totalSize * show;\n\
gl_Position *= show;\n\
v_pickColor = pickColor;\n\
}\n\
";

  var SHOW_INDEX$5 = PointPrimitive.SHOW_INDEX;
  var POSITION_INDEX$5 = PointPrimitive.POSITION_INDEX;
  var COLOR_INDEX$3 = PointPrimitive.COLOR_INDEX;
  var OUTLINE_COLOR_INDEX$1 = PointPrimitive.OUTLINE_COLOR_INDEX;
  var OUTLINE_WIDTH_INDEX$1 = PointPrimitive.OUTLINE_WIDTH_INDEX;
  var PIXEL_SIZE_INDEX$1 = PointPrimitive.PIXEL_SIZE_INDEX;
  var SCALE_BY_DISTANCE_INDEX$3 = PointPrimitive.SCALE_BY_DISTANCE_INDEX;
  var TRANSLUCENCY_BY_DISTANCE_INDEX$3 =
    PointPrimitive.TRANSLUCENCY_BY_DISTANCE_INDEX;
  var DISTANCE_DISPLAY_CONDITION_INDEX$2 =
    PointPrimitive.DISTANCE_DISPLAY_CONDITION_INDEX;
  var DISABLE_DEPTH_DISTANCE_INDEX$1 = PointPrimitive.DISABLE_DEPTH_DISTANCE_INDEX;
  var NUMBER_OF_PROPERTIES$3 = PointPrimitive.NUMBER_OF_PROPERTIES;

  var attributeLocations$3 = {
    positionHighAndSize: 0,
    positionLowAndOutline: 1,
    compressedAttribute0: 2, // color, outlineColor, pick color
    compressedAttribute1: 3, // show, translucency by distance, some free space
    scaleByDistance: 4,
    distanceDisplayConditionAndDisableDepth: 5,
  };

  /**
   * A renderable collection of points.
   * <br /><br />
   * Points are added and removed from the collection using {@link PointPrimitiveCollection#add}
   * and {@link PointPrimitiveCollection#remove}.
   *
   * @alias PointPrimitiveCollection
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms each point from model to world coordinates.
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   * @param {BlendOption} [options.blendOption=BlendOption.OPAQUE_AND_TRANSLUCENT] The point blending option. The default
   * is used for rendering both opaque and translucent points. However, if either all of the points are completely opaque or all are completely translucent,
   * setting the technique to BlendOption.OPAQUE or BlendOption.TRANSLUCENT can improve performance by up to 2x.
   *
   * @performance For best performance, prefer a few collections, each with many points, to
   * many collections with only a few points each.  Organize collections so that points
   * with the same update frequency are in the same collection, i.e., points that do not
   * change should be in one collection; points that change every frame should be in another
   * collection; and so on.
   *
   *
   * @example
   * // Create a pointPrimitive collection with two points
   * var points = scene.primitives.add(new Cesium.PointPrimitiveCollection());
   * points.add({
   *   position : new Cesium.Cartesian3(1.0, 2.0, 3.0),
   *   color : Cesium.Color.YELLOW
   * });
   * points.add({
   *   position : new Cesium.Cartesian3(4.0, 5.0, 6.0),
   *   color : Cesium.Color.CYAN
   * });
   *
   * @see PointPrimitiveCollection#add
   * @see PointPrimitiveCollection#remove
   * @see PointPrimitive
   */
  function PointPrimitiveCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._sp = undefined;
    this._spTranslucent = undefined;
    this._rsOpaque = undefined;
    this._rsTranslucent = undefined;
    this._vaf = undefined;

    this._pointPrimitives = [];
    this._pointPrimitivesToUpdate = [];
    this._pointPrimitivesToUpdateIndex = 0;
    this._pointPrimitivesRemoved = false;
    this._createVertexArray = false;

    this._shaderScaleByDistance = false;
    this._compiledShaderScaleByDistance = false;

    this._shaderTranslucencyByDistance = false;
    this._compiledShaderTranslucencyByDistance = false;

    this._shaderDistanceDisplayCondition = false;
    this._compiledShaderDistanceDisplayCondition = false;

    this._shaderDisableDepthDistance = false;
    this._compiledShaderDisableDepthDistance = false;

    this._propertiesChanged = new Uint32Array(NUMBER_OF_PROPERTIES$3);

    this._maxPixelSize = 1.0;

    this._baseVolume = new BoundingSphere();
    this._baseVolumeWC = new BoundingSphere();
    this._baseVolume2D = new BoundingSphere();
    this._boundingVolume = new BoundingSphere();
    this._boundingVolumeDirty = false;

    this._colorCommands = [];

    /**
     * The 4x4 transformation matrix that transforms each point in this collection from model to world coordinates.
     * When this is the identity matrix, the pointPrimitives are drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type {Matrix4}
     * @default {@link Matrix4.IDENTITY}
     *
     *
     * @example
     * var center = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
     * pointPrimitives.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(center);
     * pointPrimitives.add({
     *   color : Cesium.Color.ORANGE,
     *   position : new Cesium.Cartesian3(0.0, 0.0, 0.0) // center
     * });
     * pointPrimitives.add({
     *   color : Cesium.Color.YELLOW,
     *   position : new Cesium.Cartesian3(1000000.0, 0.0, 0.0) // east
     * });
     * pointPrimitives.add({
     *   color : Cesium.Color.GREEN,
     *   position : new Cesium.Cartesian3(0.0, 1000000.0, 0.0) // north
     * });
     * pointPrimitives.add({
     *   color : Cesium.Color.CYAN,
     *   position : new Cesium.Cartesian3(0.0, 0.0, 1000000.0) // up
     * });
     *
     * @see Transforms.eastNorthUpToFixedFrame
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = Matrix4.clone(Matrix4.IDENTITY);

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * The point blending option. The default is used for rendering both opaque and translucent points.
     * However, if either all of the points are completely opaque or all are completely translucent,
     * setting the technique to BlendOption.OPAQUE or BlendOption.TRANSLUCENT can improve
     * performance by up to 2x.
     * @type {BlendOption}
     * @default BlendOption.OPAQUE_AND_TRANSLUCENT
     */
    this.blendOption = defaultValue(
      options.blendOption,
      BlendOption$1.OPAQUE_AND_TRANSLUCENT
    );
    this._blendOption = undefined;

    this._mode = SceneMode$1.SCENE3D;
    this._maxTotalPointSize = 1;

    // The buffer usage for each attribute is determined based on the usage of the attribute over time.
    this._buffersUsage = [
      BufferUsage$1.STATIC_DRAW, // SHOW_INDEX
      BufferUsage$1.STATIC_DRAW, // POSITION_INDEX
      BufferUsage$1.STATIC_DRAW, // COLOR_INDEX
      BufferUsage$1.STATIC_DRAW, // OUTLINE_COLOR_INDEX
      BufferUsage$1.STATIC_DRAW, // OUTLINE_WIDTH_INDEX
      BufferUsage$1.STATIC_DRAW, // PIXEL_SIZE_INDEX
      BufferUsage$1.STATIC_DRAW, // SCALE_BY_DISTANCE_INDEX
      BufferUsage$1.STATIC_DRAW, // TRANSLUCENCY_BY_DISTANCE_INDEX
      BufferUsage$1.STATIC_DRAW, // DISTANCE_DISPLAY_CONDITION_INDEX
    ];

    var that = this;
    this._uniforms = {
      u_maxTotalPointSize: function () {
        return that._maxTotalPointSize;
      },
    };
  }

  Object.defineProperties(PointPrimitiveCollection.prototype, {
    /**
     * Returns the number of points in this collection.  This is commonly used with
     * {@link PointPrimitiveCollection#get} to iterate over all the points
     * in the collection.
     * @memberof PointPrimitiveCollection.prototype
     * @type {Number}
     */
    length: {
      get: function () {
        removePointPrimitives(this);
        return this._pointPrimitives.length;
      },
    },
  });

  function destroyPointPrimitives(pointPrimitives) {
    var length = pointPrimitives.length;
    for (var i = 0; i < length; ++i) {
      if (pointPrimitives[i]) {
        pointPrimitives[i]._destroy();
      }
    }
  }

  /**
   * Creates and adds a point with the specified initial properties to the collection.
   * The added point is returned so it can be modified or removed from the collection later.
   *
   * @param {Object}[options] A template describing the point's properties as shown in Example 1.
   * @returns {PointPrimitive} The point that was added to the collection.
   *
   * @performance Calling <code>add</code> is expected constant time.  However, the collection's vertex buffer
   * is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.  For
   * best performance, add as many pointPrimitives as possible before calling <code>update</code>.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Example 1:  Add a point, specifying all the default values.
   * var p = pointPrimitives.add({
   *   show : true,
   *   position : Cesium.Cartesian3.ZERO,
   *   pixelSize : 10.0,
   *   color : Cesium.Color.WHITE,
   *   outlineColor : Cesium.Color.TRANSPARENT,
   *   outlineWidth : 0.0,
   *   id : undefined
   * });
   *
   * @example
   * // Example 2:  Specify only the point's cartographic position.
   * var p = pointPrimitives.add({
   *   position : Cesium.Cartesian3.fromDegrees(longitude, latitude, height)
   * });
   *
   * @see PointPrimitiveCollection#remove
   * @see PointPrimitiveCollection#removeAll
   */
  PointPrimitiveCollection.prototype.add = function (options) {
    var p = new PointPrimitive(options, this);
    p._index = this._pointPrimitives.length;

    this._pointPrimitives.push(p);
    this._createVertexArray = true;

    return p;
  };

  /**
   * Removes a point from the collection.
   *
   * @param {PointPrimitive} pointPrimitive The point to remove.
   * @returns {Boolean} <code>true</code> if the point was removed; <code>false</code> if the point was not found in the collection.
   *
   * @performance Calling <code>remove</code> is expected constant time.  However, the collection's vertex buffer
   * is rewritten - an <code>O(n)</code> operation that also incurs CPU to GPU overhead.  For
   * best performance, remove as many points as possible before calling <code>update</code>.
   * If you intend to temporarily hide a point, it is usually more efficient to call
   * {@link PointPrimitive#show} instead of removing and re-adding the point.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * var p = pointPrimitives.add(...);
   * pointPrimitives.remove(p);  // Returns true
   *
   * @see PointPrimitiveCollection#add
   * @see PointPrimitiveCollection#removeAll
   * @see PointPrimitive#show
   */
  PointPrimitiveCollection.prototype.remove = function (pointPrimitive) {
    if (this.contains(pointPrimitive)) {
      this._pointPrimitives[pointPrimitive._index] = null; // Removed later
      this._pointPrimitivesRemoved = true;
      this._createVertexArray = true;
      pointPrimitive._destroy();
      return true;
    }

    return false;
  };

  /**
   * Removes all points from the collection.
   *
   * @performance <code>O(n)</code>.  It is more efficient to remove all the points
   * from a collection and then add new ones than to create a new collection entirely.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * pointPrimitives.add(...);
   * pointPrimitives.add(...);
   * pointPrimitives.removeAll();
   *
   * @see PointPrimitiveCollection#add
   * @see PointPrimitiveCollection#remove
   */
  PointPrimitiveCollection.prototype.removeAll = function () {
    destroyPointPrimitives(this._pointPrimitives);
    this._pointPrimitives = [];
    this._pointPrimitivesToUpdate = [];
    this._pointPrimitivesToUpdateIndex = 0;
    this._pointPrimitivesRemoved = false;

    this._createVertexArray = true;
  };

  function removePointPrimitives(pointPrimitiveCollection) {
    if (pointPrimitiveCollection._pointPrimitivesRemoved) {
      pointPrimitiveCollection._pointPrimitivesRemoved = false;

      var newPointPrimitives = [];
      var pointPrimitives = pointPrimitiveCollection._pointPrimitives;
      var length = pointPrimitives.length;
      for (var i = 0, j = 0; i < length; ++i) {
        var pointPrimitive = pointPrimitives[i];
        if (pointPrimitive) {
          pointPrimitive._index = j++;
          newPointPrimitives.push(pointPrimitive);
        }
      }

      pointPrimitiveCollection._pointPrimitives = newPointPrimitives;
    }
  }

  PointPrimitiveCollection.prototype._updatePointPrimitive = function (
    pointPrimitive,
    propertyChanged
  ) {
    if (!pointPrimitive._dirty) {
      this._pointPrimitivesToUpdate[
        this._pointPrimitivesToUpdateIndex++
      ] = pointPrimitive;
    }

    ++this._propertiesChanged[propertyChanged];
  };

  /**
   * Check whether this collection contains a given point.
   *
   * @param {PointPrimitive} [pointPrimitive] The point to check for.
   * @returns {Boolean} true if this collection contains the point, false otherwise.
   *
   * @see PointPrimitiveCollection#get
   */
  PointPrimitiveCollection.prototype.contains = function (pointPrimitive) {
    return (
      defined(pointPrimitive) && pointPrimitive._pointPrimitiveCollection === this
    );
  };

  /**
   * Returns the point in the collection at the specified index.  Indices are zero-based
   * and increase as points are added.  Removing a point shifts all points after
   * it to the left, changing their indices.  This function is commonly used with
   * {@link PointPrimitiveCollection#length} to iterate over all the points
   * in the collection.
   *
   * @param {Number} index The zero-based index of the point.
   * @returns {PointPrimitive} The point at the specified index.
   *
   * @performance Expected constant time.  If points were removed from the collection and
   * {@link PointPrimitiveCollection#update} was not called, an implicit <code>O(n)</code>
   * operation is performed.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Toggle the show property of every point in the collection
   * var len = pointPrimitives.length;
   * for (var i = 0; i < len; ++i) {
   *   var p = pointPrimitives.get(i);
   *   p.show = !p.show;
   * }
   *
   * @see PointPrimitiveCollection#length
   */
  PointPrimitiveCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    removePointPrimitives(this);
    return this._pointPrimitives[index];
  };

  PointPrimitiveCollection.prototype.computeNewBuffersUsage = function () {
    var buffersUsage = this._buffersUsage;
    var usageChanged = false;

    var properties = this._propertiesChanged;
    for (var k = 0; k < NUMBER_OF_PROPERTIES$3; ++k) {
      var newUsage =
        properties[k] === 0 ? BufferUsage$1.STATIC_DRAW : BufferUsage$1.STREAM_DRAW;
      usageChanged = usageChanged || buffersUsage[k] !== newUsage;
      buffersUsage[k] = newUsage;
    }

    return usageChanged;
  };

  function createVAF$1(context, numberOfPointPrimitives, buffersUsage) {
    return new VertexArrayFacade(
      context,
      [
        {
          index: attributeLocations$3.positionHighAndSize,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          usage: buffersUsage[POSITION_INDEX$5],
        },
        {
          index: attributeLocations$3.positionLowAndShow,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          usage: buffersUsage[POSITION_INDEX$5],
        },
        {
          index: attributeLocations$3.compressedAttribute0,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          usage: buffersUsage[COLOR_INDEX$3],
        },
        {
          index: attributeLocations$3.compressedAttribute1,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          usage: buffersUsage[TRANSLUCENCY_BY_DISTANCE_INDEX$3],
        },
        {
          index: attributeLocations$3.scaleByDistance,
          componentsPerAttribute: 4,
          componentDatatype: ComponentDatatype$1.FLOAT,
          usage: buffersUsage[SCALE_BY_DISTANCE_INDEX$3],
        },
        {
          index: attributeLocations$3.distanceDisplayConditionAndDisableDepth,
          componentsPerAttribute: 3,
          componentDatatype: ComponentDatatype$1.FLOAT,
          usage: buffersUsage[DISTANCE_DISPLAY_CONDITION_INDEX$2],
        },
      ],
      numberOfPointPrimitives
    ); // 1 vertex per pointPrimitive
  }

  ///////////////////////////////////////////////////////////////////////////

  // PERFORMANCE_IDEA:  Save memory if a property is the same for all pointPrimitives, use a latched attribute state,
  // instead of storing it in a vertex buffer.

  var writePositionScratch$1 = new EncodedCartesian3();

  function writePositionSizeAndOutline(
    pointPrimitiveCollection,
    context,
    vafWriters,
    pointPrimitive
  ) {
    var i = pointPrimitive._index;
    var position = pointPrimitive._getActualPosition();

    if (pointPrimitiveCollection._mode === SceneMode$1.SCENE3D) {
      BoundingSphere.expand(
        pointPrimitiveCollection._baseVolume,
        position,
        pointPrimitiveCollection._baseVolume
      );
      pointPrimitiveCollection._boundingVolumeDirty = true;
    }

    EncodedCartesian3.fromCartesian(position, writePositionScratch$1);
    var pixelSize = pointPrimitive.pixelSize;
    var outlineWidth = pointPrimitive.outlineWidth;

    pointPrimitiveCollection._maxPixelSize = Math.max(
      pointPrimitiveCollection._maxPixelSize,
      pixelSize + outlineWidth
    );

    var positionHighWriter = vafWriters[attributeLocations$3.positionHighAndSize];
    var high = writePositionScratch$1.high;
    positionHighWriter(i, high.x, high.y, high.z, pixelSize);

    var positionLowWriter = vafWriters[attributeLocations$3.positionLowAndOutline];
    var low = writePositionScratch$1.low;
    positionLowWriter(i, low.x, low.y, low.z, outlineWidth);
  }

  var LEFT_SHIFT16$1 = 65536.0; // 2^16
  var LEFT_SHIFT8$1 = 256.0; // 2^8

  function writeCompressedAttrib0$1(
    pointPrimitiveCollection,
    context,
    vafWriters,
    pointPrimitive
  ) {
    var i = pointPrimitive._index;

    var color = pointPrimitive.color;
    var pickColor = pointPrimitive.getPickId(context).color;
    var outlineColor = pointPrimitive.outlineColor;

    var red = Color.floatToByte(color.red);
    var green = Color.floatToByte(color.green);
    var blue = Color.floatToByte(color.blue);
    var compressed0 = red * LEFT_SHIFT16$1 + green * LEFT_SHIFT8$1 + blue;

    red = Color.floatToByte(outlineColor.red);
    green = Color.floatToByte(outlineColor.green);
    blue = Color.floatToByte(outlineColor.blue);
    var compressed1 = red * LEFT_SHIFT16$1 + green * LEFT_SHIFT8$1 + blue;

    red = Color.floatToByte(pickColor.red);
    green = Color.floatToByte(pickColor.green);
    blue = Color.floatToByte(pickColor.blue);
    var compressed2 = red * LEFT_SHIFT16$1 + green * LEFT_SHIFT8$1 + blue;

    var compressed3 =
      Color.floatToByte(color.alpha) * LEFT_SHIFT16$1 +
      Color.floatToByte(outlineColor.alpha) * LEFT_SHIFT8$1 +
      Color.floatToByte(pickColor.alpha);

    var writer = vafWriters[attributeLocations$3.compressedAttribute0];
    writer(i, compressed0, compressed1, compressed2, compressed3);
  }

  function writeCompressedAttrib1$1(
    pointPrimitiveCollection,
    context,
    vafWriters,
    pointPrimitive
  ) {
    var i = pointPrimitive._index;

    var near = 0.0;
    var nearValue = 1.0;
    var far = 1.0;
    var farValue = 1.0;

    var translucency = pointPrimitive.translucencyByDistance;
    if (defined(translucency)) {
      near = translucency.near;
      nearValue = translucency.nearValue;
      far = translucency.far;
      farValue = translucency.farValue;

      if (nearValue !== 1.0 || farValue !== 1.0) {
        // translucency by distance calculation in shader need not be enabled
        // until a pointPrimitive with near and far !== 1.0 is found
        pointPrimitiveCollection._shaderTranslucencyByDistance = true;
      }
    }

    var show = pointPrimitive.show && pointPrimitive.clusterShow;

    // If the color alphas are zero, do not show this pointPrimitive.  This lets us avoid providing
    // color during the pick pass and also eliminates a discard in the fragment shader.
    if (
      pointPrimitive.color.alpha === 0.0 &&
      pointPrimitive.outlineColor.alpha === 0.0
    ) {
      show = false;
    }

    nearValue = CesiumMath.clamp(nearValue, 0.0, 1.0);
    nearValue = nearValue === 1.0 ? 255.0 : (nearValue * 255.0) | 0;
    var compressed0 = (show ? 1.0 : 0.0) * LEFT_SHIFT8$1 + nearValue;

    farValue = CesiumMath.clamp(farValue, 0.0, 1.0);
    farValue = farValue === 1.0 ? 255.0 : (farValue * 255.0) | 0;
    var compressed1 = farValue;

    var writer = vafWriters[attributeLocations$3.compressedAttribute1];
    writer(i, compressed0, compressed1, near, far);
  }

  function writeScaleByDistance$1(
    pointPrimitiveCollection,
    context,
    vafWriters,
    pointPrimitive
  ) {
    var i = pointPrimitive._index;
    var writer = vafWriters[attributeLocations$3.scaleByDistance];
    var near = 0.0;
    var nearValue = 1.0;
    var far = 1.0;
    var farValue = 1.0;

    var scale = pointPrimitive.scaleByDistance;
    if (defined(scale)) {
      near = scale.near;
      nearValue = scale.nearValue;
      far = scale.far;
      farValue = scale.farValue;

      if (nearValue !== 1.0 || farValue !== 1.0) {
        // scale by distance calculation in shader need not be enabled
        // until a pointPrimitive with near and far !== 1.0 is found
        pointPrimitiveCollection._shaderScaleByDistance = true;
      }
    }

    writer(i, near, nearValue, far, farValue);
  }

  function writeDistanceDisplayConditionAndDepthDisable(
    pointPrimitiveCollection,
    context,
    vafWriters,
    pointPrimitive
  ) {
    var i = pointPrimitive._index;
    var writer =
      vafWriters[attributeLocations$3.distanceDisplayConditionAndDisableDepth];
    var near = 0.0;
    var far = Number.MAX_VALUE;

    var distanceDisplayCondition = pointPrimitive.distanceDisplayCondition;
    if (defined(distanceDisplayCondition)) {
      near = distanceDisplayCondition.near;
      far = distanceDisplayCondition.far;

      near *= near;
      far *= far;

      pointPrimitiveCollection._shaderDistanceDisplayCondition = true;
    }

    var disableDepthTestDistance = pointPrimitive.disableDepthTestDistance;
    disableDepthTestDistance *= disableDepthTestDistance;
    if (disableDepthTestDistance > 0.0) {
      pointPrimitiveCollection._shaderDisableDepthDistance = true;
      if (disableDepthTestDistance === Number.POSITIVE_INFINITY) {
        disableDepthTestDistance = -1.0;
      }
    }

    writer(i, near, far, disableDepthTestDistance);
  }

  function writePointPrimitive(
    pointPrimitiveCollection,
    context,
    vafWriters,
    pointPrimitive
  ) {
    writePositionSizeAndOutline(
      pointPrimitiveCollection,
      context,
      vafWriters,
      pointPrimitive
    );
    writeCompressedAttrib0$1(
      pointPrimitiveCollection,
      context,
      vafWriters,
      pointPrimitive
    );
    writeCompressedAttrib1$1(
      pointPrimitiveCollection,
      context,
      vafWriters,
      pointPrimitive
    );
    writeScaleByDistance$1(
      pointPrimitiveCollection,
      context,
      vafWriters,
      pointPrimitive
    );
    writeDistanceDisplayConditionAndDepthDisable(
      pointPrimitiveCollection,
      context,
      vafWriters,
      pointPrimitive
    );
  }

  function recomputeActualPositions$1(
    pointPrimitiveCollection,
    pointPrimitives,
    length,
    frameState,
    modelMatrix,
    recomputeBoundingVolume
  ) {
    var boundingVolume;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      boundingVolume = pointPrimitiveCollection._baseVolume;
      pointPrimitiveCollection._boundingVolumeDirty = true;
    } else {
      boundingVolume = pointPrimitiveCollection._baseVolume2D;
    }

    var positions = [];
    for (var i = 0; i < length; ++i) {
      var pointPrimitive = pointPrimitives[i];
      var position = pointPrimitive.position;
      var actualPosition = PointPrimitive._computeActualPosition(
        position,
        frameState,
        modelMatrix
      );
      if (defined(actualPosition)) {
        pointPrimitive._setActualPosition(actualPosition);

        if (recomputeBoundingVolume) {
          positions.push(actualPosition);
        } else {
          BoundingSphere.expand(boundingVolume, actualPosition, boundingVolume);
        }
      }
    }

    if (recomputeBoundingVolume) {
      BoundingSphere.fromPoints(positions, boundingVolume);
    }
  }

  function updateMode$2(pointPrimitiveCollection, frameState) {
    var mode = frameState.mode;

    var pointPrimitives = pointPrimitiveCollection._pointPrimitives;
    var pointPrimitivesToUpdate =
      pointPrimitiveCollection._pointPrimitivesToUpdate;
    var modelMatrix = pointPrimitiveCollection._modelMatrix;

    if (
      pointPrimitiveCollection._createVertexArray ||
      pointPrimitiveCollection._mode !== mode ||
      (mode !== SceneMode$1.SCENE3D &&
        !Matrix4.equals(modelMatrix, pointPrimitiveCollection.modelMatrix))
    ) {
      pointPrimitiveCollection._mode = mode;
      Matrix4.clone(pointPrimitiveCollection.modelMatrix, modelMatrix);
      pointPrimitiveCollection._createVertexArray = true;

      if (
        mode === SceneMode$1.SCENE3D ||
        mode === SceneMode$1.SCENE2D ||
        mode === SceneMode$1.COLUMBUS_VIEW
      ) {
        recomputeActualPositions$1(
          pointPrimitiveCollection,
          pointPrimitives,
          pointPrimitives.length,
          frameState,
          modelMatrix,
          true
        );
      }
    } else if (mode === SceneMode$1.MORPHING) {
      recomputeActualPositions$1(
        pointPrimitiveCollection,
        pointPrimitives,
        pointPrimitives.length,
        frameState,
        modelMatrix,
        true
      );
    } else if (mode === SceneMode$1.SCENE2D || mode === SceneMode$1.COLUMBUS_VIEW) {
      recomputeActualPositions$1(
        pointPrimitiveCollection,
        pointPrimitivesToUpdate,
        pointPrimitiveCollection._pointPrimitivesToUpdateIndex,
        frameState,
        modelMatrix,
        false
      );
    }
  }

  function updateBoundingVolume$1(collection, frameState, boundingVolume) {
    var pixelSize = frameState.camera.getPixelSize(
      boundingVolume,
      frameState.context.drawingBufferWidth,
      frameState.context.drawingBufferHeight
    );
    var size = pixelSize * collection._maxPixelSize;
    boundingVolume.radius += size;
  }

  var scratchWriterArray$1 = [];

  /**
   * @private
   */
  PointPrimitiveCollection.prototype.update = function (frameState) {
    removePointPrimitives(this);

    this._maxTotalPointSize = ContextLimits.maximumAliasedPointSize;

    updateMode$2(this, frameState);

    var pointPrimitives = this._pointPrimitives;
    var pointPrimitivesLength = pointPrimitives.length;
    var pointPrimitivesToUpdate = this._pointPrimitivesToUpdate;
    var pointPrimitivesToUpdateLength = this._pointPrimitivesToUpdateIndex;

    var properties = this._propertiesChanged;

    var createVertexArray = this._createVertexArray;

    var vafWriters;
    var context = frameState.context;
    var pass = frameState.passes;
    var picking = pass.pick;

    // PERFORMANCE_IDEA: Round robin multiple buffers.
    if (createVertexArray || (!picking && this.computeNewBuffersUsage())) {
      this._createVertexArray = false;

      for (var k = 0; k < NUMBER_OF_PROPERTIES$3; ++k) {
        properties[k] = 0;
      }

      this._vaf = this._vaf && this._vaf.destroy();

      if (pointPrimitivesLength > 0) {
        // PERFORMANCE_IDEA:  Instead of creating a new one, resize like std::vector.
        this._vaf = createVAF$1(context, pointPrimitivesLength, this._buffersUsage);
        vafWriters = this._vaf.writers;

        // Rewrite entire buffer if pointPrimitives were added or removed.
        for (var i = 0; i < pointPrimitivesLength; ++i) {
          var pointPrimitive = this._pointPrimitives[i];
          pointPrimitive._dirty = false; // In case it needed an update.
          writePointPrimitive(this, context, vafWriters, pointPrimitive);
        }

        this._vaf.commit();
      }

      this._pointPrimitivesToUpdateIndex = 0;
    } else if (pointPrimitivesToUpdateLength > 0) {
      // PointPrimitives were modified, but none were added or removed.
      var writers = scratchWriterArray$1;
      writers.length = 0;

      if (
        properties[POSITION_INDEX$5] ||
        properties[OUTLINE_WIDTH_INDEX$1] ||
        properties[PIXEL_SIZE_INDEX$1]
      ) {
        writers.push(writePositionSizeAndOutline);
      }

      if (properties[COLOR_INDEX$3] || properties[OUTLINE_COLOR_INDEX$1]) {
        writers.push(writeCompressedAttrib0$1);
      }

      if (properties[SHOW_INDEX$5] || properties[TRANSLUCENCY_BY_DISTANCE_INDEX$3]) {
        writers.push(writeCompressedAttrib1$1);
      }

      if (properties[SCALE_BY_DISTANCE_INDEX$3]) {
        writers.push(writeScaleByDistance$1);
      }

      if (
        properties[DISTANCE_DISPLAY_CONDITION_INDEX$2] ||
        properties[DISABLE_DEPTH_DISTANCE_INDEX$1]
      ) {
        writers.push(writeDistanceDisplayConditionAndDepthDisable);
      }

      var numWriters = writers.length;

      vafWriters = this._vaf.writers;

      if (pointPrimitivesToUpdateLength / pointPrimitivesLength > 0.1) {
        // If more than 10% of pointPrimitive change, rewrite the entire buffer.

        // PERFORMANCE_IDEA:  I totally made up 10% :).

        for (var m = 0; m < pointPrimitivesToUpdateLength; ++m) {
          var b = pointPrimitivesToUpdate[m];
          b._dirty = false;

          for (var n = 0; n < numWriters; ++n) {
            writers[n](this, context, vafWriters, b);
          }
        }
        this._vaf.commit();
      } else {
        for (var h = 0; h < pointPrimitivesToUpdateLength; ++h) {
          var bb = pointPrimitivesToUpdate[h];
          bb._dirty = false;

          for (var o = 0; o < numWriters; ++o) {
            writers[o](this, context, vafWriters, bb);
          }
          this._vaf.subCommit(bb._index, 1);
        }
        this._vaf.endSubCommits();
      }

      this._pointPrimitivesToUpdateIndex = 0;
    }

    // If the number of total pointPrimitives ever shrinks considerably
    // Truncate pointPrimitivesToUpdate so that we free memory that we're
    // not going to be using.
    if (pointPrimitivesToUpdateLength > pointPrimitivesLength * 1.5) {
      pointPrimitivesToUpdate.length = pointPrimitivesLength;
    }

    if (!defined(this._vaf) || !defined(this._vaf.va)) {
      return;
    }

    if (this._boundingVolumeDirty) {
      this._boundingVolumeDirty = false;
      BoundingSphere.transform(
        this._baseVolume,
        this.modelMatrix,
        this._baseVolumeWC
      );
    }

    var boundingVolume;
    var modelMatrix = Matrix4.IDENTITY;
    if (frameState.mode === SceneMode$1.SCENE3D) {
      modelMatrix = this.modelMatrix;
      boundingVolume = BoundingSphere.clone(
        this._baseVolumeWC,
        this._boundingVolume
      );
    } else {
      boundingVolume = BoundingSphere.clone(
        this._baseVolume2D,
        this._boundingVolume
      );
    }
    updateBoundingVolume$1(this, frameState, boundingVolume);

    var blendOptionChanged = this._blendOption !== this.blendOption;
    this._blendOption = this.blendOption;

    if (blendOptionChanged) {
      if (
        this._blendOption === BlendOption$1.OPAQUE ||
        this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT
      ) {
        this._rsOpaque = RenderState.fromCache({
          depthTest: {
            enabled: true,
            func: WebGLConstants$1.LEQUAL,
          },
          depthMask: true,
        });
      } else {
        this._rsOpaque = undefined;
      }

      if (
        this._blendOption === BlendOption$1.TRANSLUCENT ||
        this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT
      ) {
        this._rsTranslucent = RenderState.fromCache({
          depthTest: {
            enabled: true,
            func: WebGLConstants$1.LEQUAL,
          },
          depthMask: false,
          blending: BlendingState$1.ALPHA_BLEND,
        });
      } else {
        this._rsTranslucent = undefined;
      }
    }

    this._shaderDisableDepthDistance =
      this._shaderDisableDepthDistance ||
      frameState.minimumDisableDepthTestDistance !== 0.0;
    var vs;
    var fs;

    if (
      blendOptionChanged ||
      (this._shaderScaleByDistance && !this._compiledShaderScaleByDistance) ||
      (this._shaderTranslucencyByDistance &&
        !this._compiledShaderTranslucencyByDistance) ||
      (this._shaderDistanceDisplayCondition &&
        !this._compiledShaderDistanceDisplayCondition) ||
      this._shaderDisableDepthDistance !==
        this._compiledShaderDisableDepthDistance
    ) {
      vs = new ShaderSource({
        sources: [PointPrimitiveCollectionVS],
      });
      if (this._shaderScaleByDistance) {
        vs.defines.push("EYE_DISTANCE_SCALING");
      }
      if (this._shaderTranslucencyByDistance) {
        vs.defines.push("EYE_DISTANCE_TRANSLUCENCY");
      }
      if (this._shaderDistanceDisplayCondition) {
        vs.defines.push("DISTANCE_DISPLAY_CONDITION");
      }
      if (this._shaderDisableDepthDistance) {
        vs.defines.push("DISABLE_DEPTH_DISTANCE");
      }

      if (this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT) {
        fs = new ShaderSource({
          defines: ["OPAQUE"],
          sources: [PointPrimitiveCollectionFS],
        });
        this._sp = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._sp,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations$3,
        });

        fs = new ShaderSource({
          defines: ["TRANSLUCENT"],
          sources: [PointPrimitiveCollectionFS],
        });
        this._spTranslucent = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._spTranslucent,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations$3,
        });
      }

      if (this._blendOption === BlendOption$1.OPAQUE) {
        fs = new ShaderSource({
          sources: [PointPrimitiveCollectionFS],
        });
        this._sp = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._sp,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations$3,
        });
      }

      if (this._blendOption === BlendOption$1.TRANSLUCENT) {
        fs = new ShaderSource({
          sources: [PointPrimitiveCollectionFS],
        });
        this._spTranslucent = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._spTranslucent,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations$3,
        });
      }

      this._compiledShaderScaleByDistance = this._shaderScaleByDistance;
      this._compiledShaderTranslucencyByDistance = this._shaderTranslucencyByDistance;
      this._compiledShaderDistanceDisplayCondition = this._shaderDistanceDisplayCondition;
      this._compiledShaderDisableDepthDistance = this._shaderDisableDepthDistance;
    }

    var va;
    var vaLength;
    var command;
    var j;

    var commandList = frameState.commandList;

    if (pass.render || picking) {
      var colorList = this._colorCommands;

      var opaque = this._blendOption === BlendOption$1.OPAQUE;
      var opaqueAndTranslucent =
        this._blendOption === BlendOption$1.OPAQUE_AND_TRANSLUCENT;

      va = this._vaf.va;
      vaLength = va.length;

      colorList.length = vaLength;
      var totalLength = opaqueAndTranslucent ? vaLength * 2 : vaLength;
      for (j = 0; j < totalLength; ++j) {
        var opaqueCommand = opaque || (opaqueAndTranslucent && j % 2 === 0);

        command = colorList[j];
        if (!defined(command)) {
          command = colorList[j] = new DrawCommand();
        }

        command.primitiveType = PrimitiveType$1.POINTS;
        command.pass =
          opaqueCommand || !opaqueAndTranslucent ? Pass$1.OPAQUE : Pass$1.TRANSLUCENT;
        command.owner = this;

        var index = opaqueAndTranslucent ? Math.floor(j / 2.0) : j;
        command.boundingVolume = boundingVolume;
        command.modelMatrix = modelMatrix;
        command.shaderProgram = opaqueCommand ? this._sp : this._spTranslucent;
        command.uniformMap = this._uniforms;
        command.vertexArray = va[index].va;
        command.renderState = opaqueCommand
          ? this._rsOpaque
          : this._rsTranslucent;
        command.debugShowBoundingVolume = this.debugShowBoundingVolume;
        command.pickId = "v_pickColor";

        commandList.push(command);
      }
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PointPrimitiveCollection#destroy
   */
  PointPrimitiveCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * pointPrimitives = pointPrimitives && pointPrimitives.destroy();
   *
   * @see PointPrimitiveCollection#isDestroyed
   */
  PointPrimitiveCollection.prototype.destroy = function () {
    this._sp = this._sp && this._sp.destroy();
    this._spTranslucent = this._spTranslucent && this._spTranslucent.destroy();
    this._spPick = this._spPick && this._spPick.destroy();
    this._vaf = this._vaf && this._vaf.destroy();
    destroyPointPrimitives(this._pointPrimitives);

    return destroyObject(this);
  };

  function kdbush(points, getX, getY, nodeSize, ArrayType) {
      return new KDBush(points, getX, getY, nodeSize, ArrayType);
  }

  function KDBush(points, getX, getY, nodeSize, ArrayType) {
      getX = getX || defaultGetX;
      getY = getY || defaultGetY;
      ArrayType = ArrayType || Array;

      this.nodeSize = nodeSize || 64;
      this.points = points;

      this.ids = new ArrayType(points.length);
      this.coords = new ArrayType(points.length * 2);

      for (var i = 0; i < points.length; i++) {
          this.ids[i] = i;
          this.coords[2 * i] = getX(points[i]);
          this.coords[2 * i + 1] = getY(points[i]);
      }

      sort$1(this.ids, this.coords, this.nodeSize, 0, this.ids.length - 1, 0);
  }

  KDBush.prototype = {
      range: function (minX, minY, maxX, maxY) {
          return range(this.ids, this.coords, minX, minY, maxX, maxY, this.nodeSize);
      },

      within: function (x, y, r) {
          return within(this.ids, this.coords, x, y, r, this.nodeSize);
      }
  };

  function defaultGetX(p) { return p[0]; }
  function defaultGetY(p) { return p[1]; }

  function range(ids, coords, minX, minY, maxX, maxY, nodeSize) {
      var stack = [0, ids.length - 1, 0];
      var result = [];
      var x, y;

      while (stack.length) {
          var axis = stack.pop();
          var right = stack.pop();
          var left = stack.pop();

          if (right - left <= nodeSize) {
              for (var i = left; i <= right; i++) {
                  x = coords[2 * i];
                  y = coords[2 * i + 1];
                  if (x >= minX && x <= maxX && y >= minY && y <= maxY) result.push(ids[i]);
              }
              continue;
          }

          var m = Math.floor((left + right) / 2);

          x = coords[2 * m];
          y = coords[2 * m + 1];

          if (x >= minX && x <= maxX && y >= minY && y <= maxY) result.push(ids[m]);

          var nextAxis = (axis + 1) % 2;

          if (axis === 0 ? minX <= x : minY <= y) {
              stack.push(left);
              stack.push(m - 1);
              stack.push(nextAxis);
          }
          if (axis === 0 ? maxX >= x : maxY >= y) {
              stack.push(m + 1);
              stack.push(right);
              stack.push(nextAxis);
          }
      }

      return result;
  }

  function sort$1(ids, coords, nodeSize, left, right, depth) {
      if (right - left <= nodeSize) return;

      var m = Math.floor((left + right) / 2);

      select(ids, coords, m, left, right, depth % 2);

      sort$1(ids, coords, nodeSize, left, m - 1, depth + 1);
      sort$1(ids, coords, nodeSize, m + 1, right, depth + 1);
  }

  function select(ids, coords, k, left, right, inc) {

      while (right > left) {
          if (right - left > 600) {
              var n = right - left + 1;
              var m = k - left + 1;
              var z = Math.log(n);
              var s = 0.5 * Math.exp(2 * z / 3);
              var sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1);
              var newLeft = Math.max(left, Math.floor(k - m * s / n + sd));
              var newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd));
              select(ids, coords, k, newLeft, newRight, inc);
          }

          var t = coords[2 * k + inc];
          var i = left;
          var j = right;

          swapItem(ids, coords, left, k);
          if (coords[2 * right + inc] > t) swapItem(ids, coords, left, right);

          while (i < j) {
              swapItem(ids, coords, i, j);
              i++;
              j--;
              while (coords[2 * i + inc] < t) i++;
              while (coords[2 * j + inc] > t) j--;
          }

          if (coords[2 * left + inc] === t) swapItem(ids, coords, left, j);
          else {
              j++;
              swapItem(ids, coords, j, right);
          }

          if (j <= k) left = j + 1;
          if (k <= j) right = j - 1;
      }
  }

  function swapItem(ids, coords, i, j) {
      swap$2(ids, i, j);
      swap$2(coords, 2 * i, 2 * j);
      swap$2(coords, 2 * i + 1, 2 * j + 1);
  }

  function swap$2(arr, i, j) {
      var tmp = arr[i];
      arr[i] = arr[j];
      arr[j] = tmp;
  }

  function within(ids, coords, qx, qy, r, nodeSize) {
      var stack = [0, ids.length - 1, 0];
      var result = [];
      var r2 = r * r;

      while (stack.length) {
          var axis = stack.pop();
          var right = stack.pop();
          var left = stack.pop();

          if (right - left <= nodeSize) {
              for (var i = left; i <= right; i++) {
                  if (sqDist(coords[2 * i], coords[2 * i + 1], qx, qy) <= r2) result.push(ids[i]);
              }
              continue;
          }

          var m = Math.floor((left + right) / 2);

          var x = coords[2 * m];
          var y = coords[2 * m + 1];

          if (sqDist(x, y, qx, qy) <= r2) result.push(ids[m]);

          var nextAxis = (axis + 1) % 2;

          if (axis === 0 ? qx - r <= x : qy - r <= y) {
              stack.push(left);
              stack.push(m - 1);
              stack.push(nextAxis);
          }
          if (axis === 0 ? qx + r >= x : qy + r >= y) {
              stack.push(m + 1);
              stack.push(right);
              stack.push(nextAxis);
          }
      }

      return result;
  }

  function sqDist(ax, ay, bx, by) {
      var dx = ax - bx;
      var dy = ay - by;
      return dx * dx + dy * dy;
  }

  /**
   * Defines how screen space objects (billboards, points, labels) are clustered.
   *
   * @param {Object} [options] An object with the following properties:
   * @param {Boolean} [options.enabled=false] Whether or not to enable clustering.
   * @param {Number} [options.pixelRange=80] The pixel range to extend the screen space bounding box.
   * @param {Number} [options.minimumClusterSize=2] The minimum number of screen space objects that can be clustered.
   * @param {Boolean} [options.clusterBillboards=true] Whether or not to cluster the billboards of an entity.
   * @param {Boolean} [options.clusterLabels=true] Whether or not to cluster the labels of an entity.
   * @param {Boolean} [options.clusterPoints=true] Whether or not to cluster the points of an entity.
   *
   * @alias EntityCluster
   * @constructor
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Clustering.html|Cesium Sandcastle Clustering Demo}
   */
  function EntityCluster(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._enabled = defaultValue(options.enabled, false);
    this._pixelRange = defaultValue(options.pixelRange, 80);
    this._minimumClusterSize = defaultValue(options.minimumClusterSize, 2);
    this._clusterBillboards = defaultValue(options.clusterBillboards, true);
    this._clusterLabels = defaultValue(options.clusterLabels, true);
    this._clusterPoints = defaultValue(options.clusterPoints, true);

    this._labelCollection = undefined;
    this._billboardCollection = undefined;
    this._pointCollection = undefined;

    this._clusterBillboardCollection = undefined;
    this._clusterLabelCollection = undefined;
    this._clusterPointCollection = undefined;

    this._collectionIndicesByEntity = {};

    this._unusedLabelIndices = [];
    this._unusedBillboardIndices = [];
    this._unusedPointIndices = [];

    this._previousClusters = [];
    this._previousHeight = undefined;

    this._enabledDirty = false;
    this._clusterDirty = false;

    this._cluster = undefined;
    this._removeEventListener = undefined;

    this._clusterEvent = new Event();
  }

  function getX(point) {
    return point.coord.x;
  }

  function getY(point) {
    return point.coord.y;
  }

  function expandBoundingBox(bbox, pixelRange) {
    bbox.x -= pixelRange;
    bbox.y -= pixelRange;
    bbox.width += pixelRange * 2.0;
    bbox.height += pixelRange * 2.0;
  }

  var labelBoundingBoxScratch = new BoundingRectangle();

  function getBoundingBox(item, coord, pixelRange, entityCluster, result) {
    if (defined(item._labelCollection) && entityCluster._clusterLabels) {
      result = Label.getScreenSpaceBoundingBox(item, coord, result);
    } else if (
      defined(item._billboardCollection) &&
      entityCluster._clusterBillboards
    ) {
      result = Billboard.getScreenSpaceBoundingBox(item, coord, result);
    } else if (
      defined(item._pointPrimitiveCollection) &&
      entityCluster._clusterPoints
    ) {
      result = PointPrimitive.getScreenSpaceBoundingBox(item, coord, result);
    }

    expandBoundingBox(result, pixelRange);

    if (
      entityCluster._clusterLabels &&
      !defined(item._labelCollection) &&
      defined(item.id) &&
      hasLabelIndex(entityCluster, item.id.id) &&
      defined(item.id._label)
    ) {
      var labelIndex =
        entityCluster._collectionIndicesByEntity[item.id.id].labelIndex;
      var label = entityCluster._labelCollection.get(labelIndex);
      var labelBBox = Label.getScreenSpaceBoundingBox(
        label,
        coord,
        labelBoundingBoxScratch
      );
      expandBoundingBox(labelBBox, pixelRange);
      result = BoundingRectangle.union(result, labelBBox, result);
    }

    return result;
  }

  function addNonClusteredItem(item, entityCluster) {
    item.clusterShow = true;

    if (
      !defined(item._labelCollection) &&
      defined(item.id) &&
      hasLabelIndex(entityCluster, item.id.id) &&
      defined(item.id._label)
    ) {
      var labelIndex =
        entityCluster._collectionIndicesByEntity[item.id.id].labelIndex;
      var label = entityCluster._labelCollection.get(labelIndex);
      label.clusterShow = true;
    }
  }

  function addCluster(position, numPoints, ids, entityCluster) {
    var cluster = {
      billboard: entityCluster._clusterBillboardCollection.add(),
      label: entityCluster._clusterLabelCollection.add(),
      point: entityCluster._clusterPointCollection.add(),
    };

    cluster.billboard.show = false;
    cluster.point.show = false;
    cluster.label.show = true;
    cluster.label.text = numPoints.toLocaleString();
    cluster.label.id = ids;
    cluster.billboard.position = cluster.label.position = cluster.point.position = position;

    entityCluster._clusterEvent.raiseEvent(ids, cluster);
  }

  function hasLabelIndex(entityCluster, entityId) {
    return (
      defined(entityCluster) &&
      defined(entityCluster._collectionIndicesByEntity[entityId]) &&
      defined(entityCluster._collectionIndicesByEntity[entityId].labelIndex)
    );
  }

  function getScreenSpacePositions(
    collection,
    points,
    scene,
    occluder,
    entityCluster
  ) {
    if (!defined(collection)) {
      return;
    }

    var length = collection.length;
    for (var i = 0; i < length; ++i) {
      var item = collection.get(i);
      item.clusterShow = false;

      if (
        !item.show ||
        (entityCluster._scene.mode === SceneMode$1.SCENE3D &&
          !occluder.isPointVisible(item.position))
      ) {
        continue;
      }

      var canClusterLabels =
        entityCluster._clusterLabels && defined(item._labelCollection);
      var canClusterBillboards =
        entityCluster._clusterBillboards && defined(item.id._billboard);
      var canClusterPoints =
        entityCluster._clusterPoints && defined(item.id._point);
      if (canClusterLabels && (canClusterPoints || canClusterBillboards)) {
        continue;
      }

      var coord = item.computeScreenSpacePosition(scene);
      if (!defined(coord)) {
        continue;
      }

      points.push({
        index: i,
        collection: collection,
        clustered: false,
        coord: coord,
      });
    }
  }

  var pointBoundinRectangleScratch = new BoundingRectangle();
  var totalBoundingRectangleScratch = new BoundingRectangle();
  var neighborBoundingRectangleScratch = new BoundingRectangle();

  function createDeclutterCallback(entityCluster) {
    return function (amount) {
      if ((defined(amount) && amount < 0.05) || !entityCluster.enabled) {
        return;
      }

      var scene = entityCluster._scene;

      var labelCollection = entityCluster._labelCollection;
      var billboardCollection = entityCluster._billboardCollection;
      var pointCollection = entityCluster._pointCollection;

      if (
        (!defined(labelCollection) &&
          !defined(billboardCollection) &&
          !defined(pointCollection)) ||
        (!entityCluster._clusterBillboards &&
          !entityCluster._clusterLabels &&
          !entityCluster._clusterPoints)
      ) {
        return;
      }

      var clusteredLabelCollection = entityCluster._clusterLabelCollection;
      var clusteredBillboardCollection =
        entityCluster._clusterBillboardCollection;
      var clusteredPointCollection = entityCluster._clusterPointCollection;

      if (defined(clusteredLabelCollection)) {
        clusteredLabelCollection.removeAll();
      } else {
        clusteredLabelCollection = entityCluster._clusterLabelCollection = new LabelCollection(
          {
            scene: scene,
          }
        );
      }

      if (defined(clusteredBillboardCollection)) {
        clusteredBillboardCollection.removeAll();
      } else {
        clusteredBillboardCollection = entityCluster._clusterBillboardCollection = new BillboardCollection(
          {
            scene: scene,
          }
        );
      }

      if (defined(clusteredPointCollection)) {
        clusteredPointCollection.removeAll();
      } else {
        clusteredPointCollection = entityCluster._clusterPointCollection = new PointPrimitiveCollection();
      }

      var pixelRange = entityCluster._pixelRange;
      var minimumClusterSize = entityCluster._minimumClusterSize;

      var clusters = entityCluster._previousClusters;
      var newClusters = [];

      var previousHeight = entityCluster._previousHeight;
      var currentHeight = scene.camera.positionCartographic.height;

      var ellipsoid = scene.mapProjection.ellipsoid;
      var cameraPosition = scene.camera.positionWC;
      var occluder = new EllipsoidalOccluder(ellipsoid, cameraPosition);

      var points = [];
      if (entityCluster._clusterLabels) {
        getScreenSpacePositions(
          labelCollection,
          points,
          scene,
          occluder,
          entityCluster
        );
      }
      if (entityCluster._clusterBillboards) {
        getScreenSpacePositions(
          billboardCollection,
          points,
          scene,
          occluder,
          entityCluster
        );
      }
      if (entityCluster._clusterPoints) {
        getScreenSpacePositions(
          pointCollection,
          points,
          scene,
          occluder,
          entityCluster
        );
      }

      var i;
      var j;
      var length;
      var bbox;
      var neighbors;
      var neighborLength;
      var neighborIndex;
      var neighborPoint;
      var ids;
      var numPoints;

      var collection;
      var collectionIndex;

      var index = kdbush(points, getX, getY, 64, Int32Array);

      if (currentHeight < previousHeight) {
        length = clusters.length;
        for (i = 0; i < length; ++i) {
          var cluster = clusters[i];

          if (!occluder.isPointVisible(cluster.position)) {
            continue;
          }

          var coord = Billboard._computeScreenSpacePosition(
            Matrix4.IDENTITY,
            cluster.position,
            Cartesian3.ZERO,
            Cartesian2.ZERO,
            scene
          );
          if (!defined(coord)) {
            continue;
          }

          var factor = 1.0 - currentHeight / previousHeight;
          var width = (cluster.width = cluster.width * factor);
          var height = (cluster.height = cluster.height * factor);

          width = Math.max(width, cluster.minimumWidth);
          height = Math.max(height, cluster.minimumHeight);

          var minX = coord.x - width * 0.5;
          var minY = coord.y - height * 0.5;
          var maxX = coord.x + width;
          var maxY = coord.y + height;

          neighbors = index.range(minX, minY, maxX, maxY);
          neighborLength = neighbors.length;
          numPoints = 0;
          ids = [];

          for (j = 0; j < neighborLength; ++j) {
            neighborIndex = neighbors[j];
            neighborPoint = points[neighborIndex];
            if (!neighborPoint.clustered) {
              ++numPoints;

              collection = neighborPoint.collection;
              collectionIndex = neighborPoint.index;
              ids.push(collection.get(collectionIndex).id);
            }
          }

          if (numPoints >= minimumClusterSize) {
            addCluster(cluster.position, numPoints, ids, entityCluster);
            newClusters.push(cluster);

            for (j = 0; j < neighborLength; ++j) {
              points[neighbors[j]].clustered = true;
            }
          }
        }
      }

      length = points.length;
      for (i = 0; i < length; ++i) {
        var point = points[i];
        if (point.clustered) {
          continue;
        }

        point.clustered = true;

        collection = point.collection;
        collectionIndex = point.index;

        var item = collection.get(collectionIndex);
        bbox = getBoundingBox(
          item,
          point.coord,
          pixelRange,
          entityCluster,
          pointBoundinRectangleScratch
        );
        var totalBBox = BoundingRectangle.clone(
          bbox,
          totalBoundingRectangleScratch
        );

        neighbors = index.range(
          bbox.x,
          bbox.y,
          bbox.x + bbox.width,
          bbox.y + bbox.height
        );
        neighborLength = neighbors.length;

        var clusterPosition = Cartesian3.clone(item.position);
        numPoints = 1;
        ids = [item.id];

        for (j = 0; j < neighborLength; ++j) {
          neighborIndex = neighbors[j];
          neighborPoint = points[neighborIndex];
          if (!neighborPoint.clustered) {
            var neighborItem = neighborPoint.collection.get(neighborPoint.index);
            var neighborBBox = getBoundingBox(
              neighborItem,
              neighborPoint.coord,
              pixelRange,
              entityCluster,
              neighborBoundingRectangleScratch
            );

            Cartesian3.add(
              neighborItem.position,
              clusterPosition,
              clusterPosition
            );

            BoundingRectangle.union(totalBBox, neighborBBox, totalBBox);
            ++numPoints;

            ids.push(neighborItem.id);
          }
        }

        if (numPoints >= minimumClusterSize) {
          var position = Cartesian3.multiplyByScalar(
            clusterPosition,
            1.0 / numPoints,
            clusterPosition
          );
          addCluster(position, numPoints, ids, entityCluster);
          newClusters.push({
            position: position,
            width: totalBBox.width,
            height: totalBBox.height,
            minimumWidth: bbox.width,
            minimumHeight: bbox.height,
          });

          for (j = 0; j < neighborLength; ++j) {
            points[neighbors[j]].clustered = true;
          }
        } else {
          addNonClusteredItem(item, entityCluster);
        }
      }

      if (clusteredLabelCollection.length === 0) {
        clusteredLabelCollection.destroy();
        entityCluster._clusterLabelCollection = undefined;
      }

      if (clusteredBillboardCollection.length === 0) {
        clusteredBillboardCollection.destroy();
        entityCluster._clusterBillboardCollection = undefined;
      }

      if (clusteredPointCollection.length === 0) {
        clusteredPointCollection.destroy();
        entityCluster._clusterPointCollection = undefined;
      }

      entityCluster._previousClusters = newClusters;
      entityCluster._previousHeight = currentHeight;
    };
  }

  EntityCluster.prototype._initialize = function (scene) {
    this._scene = scene;

    var cluster = createDeclutterCallback(this);
    this._cluster = cluster;
    this._removeEventListener = scene.camera.changed.addEventListener(cluster);
  };

  Object.defineProperties(EntityCluster.prototype, {
    /**
     * Gets or sets whether clustering is enabled.
     * @memberof EntityCluster.prototype
     * @type {Boolean}
     */
    enabled: {
      get: function () {
        return this._enabled;
      },
      set: function (value) {
        this._enabledDirty = value !== this._enabled;
        this._enabled = value;
      },
    },
    /**
     * Gets or sets the pixel range to extend the screen space bounding box.
     * @memberof EntityCluster.prototype
     * @type {Number}
     */
    pixelRange: {
      get: function () {
        return this._pixelRange;
      },
      set: function (value) {
        this._clusterDirty = this._clusterDirty || value !== this._pixelRange;
        this._pixelRange = value;
      },
    },
    /**
     * Gets or sets the minimum number of screen space objects that can be clustered.
     * @memberof EntityCluster.prototype
     * @type {Number}
     */
    minimumClusterSize: {
      get: function () {
        return this._minimumClusterSize;
      },
      set: function (value) {
        this._clusterDirty =
          this._clusterDirty || value !== this._minimumClusterSize;
        this._minimumClusterSize = value;
      },
    },
    /**
     * Gets the event that will be raised when a new cluster will be displayed. The signature of the event listener is {@link EntityCluster.newClusterCallback}.
     * @memberof EntityCluster.prototype
     * @type {Event}
     */
    clusterEvent: {
      get: function () {
        return this._clusterEvent;
      },
    },
    /**
     * Gets or sets whether clustering billboard entities is enabled.
     * @memberof EntityCluster.prototype
     * @type {Boolean}
     */
    clusterBillboards: {
      get: function () {
        return this._clusterBillboards;
      },
      set: function (value) {
        this._clusterDirty =
          this._clusterDirty || value !== this._clusterBillboards;
        this._clusterBillboards = value;
      },
    },
    /**
     * Gets or sets whether clustering labels entities is enabled.
     * @memberof EntityCluster.prototype
     * @type {Boolean}
     */
    clusterLabels: {
      get: function () {
        return this._clusterLabels;
      },
      set: function (value) {
        this._clusterDirty = this._clusterDirty || value !== this._clusterLabels;
        this._clusterLabels = value;
      },
    },
    /**
     * Gets or sets whether clustering point entities is enabled.
     * @memberof EntityCluster.prototype
     * @type {Boolean}
     */
    clusterPoints: {
      get: function () {
        return this._clusterPoints;
      },
      set: function (value) {
        this._clusterDirty = this._clusterDirty || value !== this._clusterPoints;
        this._clusterPoints = value;
      },
    },
  });

  function createGetEntity(
    collectionProperty,
    CollectionConstructor,
    unusedIndicesProperty,
    entityIndexProperty
  ) {
    return function (entity) {
      var collection = this[collectionProperty];

      if (!defined(this._collectionIndicesByEntity)) {
        this._collectionIndicesByEntity = {};
      }

      var entityIndices = this._collectionIndicesByEntity[entity.id];

      if (!defined(entityIndices)) {
        entityIndices = this._collectionIndicesByEntity[entity.id] = {
          billboardIndex: undefined,
          labelIndex: undefined,
          pointIndex: undefined,
        };
      }

      if (defined(collection) && defined(entityIndices[entityIndexProperty])) {
        return collection.get(entityIndices[entityIndexProperty]);
      }

      if (!defined(collection)) {
        collection = this[collectionProperty] = new CollectionConstructor({
          scene: this._scene,
        });
      }

      var index;
      var entityItem;

      var unusedIndices = this[unusedIndicesProperty];
      if (unusedIndices.length > 0) {
        index = unusedIndices.pop();
        entityItem = collection.get(index);
      } else {
        entityItem = collection.add();
        index = collection.length - 1;
      }

      entityIndices[entityIndexProperty] = index;

      this._clusterDirty = true;

      return entityItem;
    };
  }

  function removeEntityIndicesIfUnused(entityCluster, entityId) {
    var indices = entityCluster._collectionIndicesByEntity[entityId];

    if (
      !defined(indices.billboardIndex) &&
      !defined(indices.labelIndex) &&
      !defined(indices.pointIndex)
    ) {
      delete entityCluster._collectionIndicesByEntity[entityId];
    }
  }

  /**
   * Returns a new {@link Label}.
   * @param {Entity} entity The entity that will use the returned {@link Label} for visualization.
   * @returns {Label} The label that will be used to visualize an entity.
   *
   * @private
   */
  EntityCluster.prototype.getLabel = createGetEntity(
    "_labelCollection",
    LabelCollection,
    "_unusedLabelIndices",
    "labelIndex"
  );

  /**
   * Removes the {@link Label} associated with an entity so it can be reused by another entity.
   * @param {Entity} entity The entity that will uses the returned {@link Label} for visualization.
   *
   * @private
   */
  EntityCluster.prototype.removeLabel = function (entity) {
    var entityIndices =
      this._collectionIndicesByEntity &&
      this._collectionIndicesByEntity[entity.id];
    if (
      !defined(this._labelCollection) ||
      !defined(entityIndices) ||
      !defined(entityIndices.labelIndex)
    ) {
      return;
    }

    var index = entityIndices.labelIndex;
    entityIndices.labelIndex = undefined;
    removeEntityIndicesIfUnused(this, entity.id);

    var label = this._labelCollection.get(index);
    label.show = false;
    label.text = "";
    label.id = undefined;

    this._unusedLabelIndices.push(index);

    this._clusterDirty = true;
  };

  /**
   * Returns a new {@link Billboard}.
   * @param {Entity} entity The entity that will use the returned {@link Billboard} for visualization.
   * @returns {Billboard} The label that will be used to visualize an entity.
   *
   * @private
   */
  EntityCluster.prototype.getBillboard = createGetEntity(
    "_billboardCollection",
    BillboardCollection,
    "_unusedBillboardIndices",
    "billboardIndex"
  );

  /**
   * Removes the {@link Billboard} associated with an entity so it can be reused by another entity.
   * @param {Entity} entity The entity that will uses the returned {@link Billboard} for visualization.
   *
   * @private
   */
  EntityCluster.prototype.removeBillboard = function (entity) {
    var entityIndices =
      this._collectionIndicesByEntity &&
      this._collectionIndicesByEntity[entity.id];
    if (
      !defined(this._billboardCollection) ||
      !defined(entityIndices) ||
      !defined(entityIndices.billboardIndex)
    ) {
      return;
    }

    var index = entityIndices.billboardIndex;
    entityIndices.billboardIndex = undefined;
    removeEntityIndicesIfUnused(this, entity.id);

    var billboard = this._billboardCollection.get(index);
    billboard.id = undefined;
    billboard.show = false;
    billboard.image = undefined;

    this._unusedBillboardIndices.push(index);

    this._clusterDirty = true;
  };

  /**
   * Returns a new {@link Point}.
   * @param {Entity} entity The entity that will use the returned {@link Point} for visualization.
   * @returns {Point} The label that will be used to visualize an entity.
   *
   * @private
   */
  EntityCluster.prototype.getPoint = createGetEntity(
    "_pointCollection",
    PointPrimitiveCollection,
    "_unusedPointIndices",
    "pointIndex"
  );

  /**
   * Removes the {@link Point} associated with an entity so it can be reused by another entity.
   * @param {Entity} entity The entity that will uses the returned {@link Point} for visualization.
   *
   * @private
   */
  EntityCluster.prototype.removePoint = function (entity) {
    var entityIndices =
      this._collectionIndicesByEntity &&
      this._collectionIndicesByEntity[entity.id];
    if (
      !defined(this._pointCollection) ||
      !defined(entityIndices) ||
      !defined(entityIndices.pointIndex)
    ) {
      return;
    }

    var index = entityIndices.pointIndex;
    entityIndices.pointIndex = undefined;
    removeEntityIndicesIfUnused(this, entity.id);

    var point = this._pointCollection.get(index);
    point.show = false;
    point.id = undefined;

    this._unusedPointIndices.push(index);

    this._clusterDirty = true;
  };

  function disableCollectionClustering(collection) {
    if (!defined(collection)) {
      return;
    }

    var length = collection.length;
    for (var i = 0; i < length; ++i) {
      collection.get(i).clusterShow = true;
    }
  }

  function updateEnable(entityCluster) {
    if (entityCluster.enabled) {
      return;
    }

    if (defined(entityCluster._clusterLabelCollection)) {
      entityCluster._clusterLabelCollection.destroy();
    }
    if (defined(entityCluster._clusterBillboardCollection)) {
      entityCluster._clusterBillboardCollection.destroy();
    }
    if (defined(entityCluster._clusterPointCollection)) {
      entityCluster._clusterPointCollection.destroy();
    }

    entityCluster._clusterLabelCollection = undefined;
    entityCluster._clusterBillboardCollection = undefined;
    entityCluster._clusterPointCollection = undefined;

    disableCollectionClustering(entityCluster._labelCollection);
    disableCollectionClustering(entityCluster._billboardCollection);
    disableCollectionClustering(entityCluster._pointCollection);
  }

  /**
   * Gets the draw commands for the clustered billboards/points/labels if enabled, otherwise,
   * queues the draw commands for billboards/points/labels created for entities.
   * @private
   */
  EntityCluster.prototype.update = function (frameState) {
    // If clustering is enabled before the label collection is updated,
    // the glyphs haven't been created so the screen space bounding boxes
    // are incorrect.
    var commandList;
    if (
      defined(this._labelCollection) &&
      this._labelCollection.length > 0 &&
      this._labelCollection.get(0)._glyphs.length === 0
    ) {
      commandList = frameState.commandList;
      frameState.commandList = [];
      this._labelCollection.update(frameState);
      frameState.commandList = commandList;
    }

    // If clustering is enabled before the billboard collection is updated,
    // the images haven't been added to the image atlas so the screen space bounding boxes
    // are incorrect.
    if (
      defined(this._billboardCollection) &&
      this._billboardCollection.length > 0 &&
      !defined(this._billboardCollection.get(0).width)
    ) {
      commandList = frameState.commandList;
      frameState.commandList = [];
      this._billboardCollection.update(frameState);
      frameState.commandList = commandList;
    }

    if (this._enabledDirty) {
      this._enabledDirty = false;
      updateEnable(this);
      this._clusterDirty = true;
    }

    if (this._clusterDirty) {
      this._clusterDirty = false;
      this._cluster();
    }

    if (defined(this._clusterLabelCollection)) {
      this._clusterLabelCollection.update(frameState);
    }
    if (defined(this._clusterBillboardCollection)) {
      this._clusterBillboardCollection.update(frameState);
    }
    if (defined(this._clusterPointCollection)) {
      this._clusterPointCollection.update(frameState);
    }

    if (defined(this._labelCollection)) {
      this._labelCollection.update(frameState);
    }
    if (defined(this._billboardCollection)) {
      this._billboardCollection.update(frameState);
    }
    if (defined(this._pointCollection)) {
      this._pointCollection.update(frameState);
    }
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Unlike other objects that use WebGL resources, this object can be reused. For example, if a data source is removed
   * from a data source collection and added to another.
   * </p>
   */
  EntityCluster.prototype.destroy = function () {
    this._labelCollection =
      this._labelCollection && this._labelCollection.destroy();
    this._billboardCollection =
      this._billboardCollection && this._billboardCollection.destroy();
    this._pointCollection =
      this._pointCollection && this._pointCollection.destroy();

    this._clusterLabelCollection =
      this._clusterLabelCollection && this._clusterLabelCollection.destroy();
    this._clusterBillboardCollection =
      this._clusterBillboardCollection &&
      this._clusterBillboardCollection.destroy();
    this._clusterPointCollection =
      this._clusterPointCollection && this._clusterPointCollection.destroy();

    if (defined(this._removeEventListener)) {
      this._removeEventListener();
      this._removeEventListener = undefined;
    }

    this._labelCollection = undefined;
    this._billboardCollection = undefined;
    this._pointCollection = undefined;

    this._clusterBillboardCollection = undefined;
    this._clusterLabelCollection = undefined;
    this._clusterPointCollection = undefined;

    this._collectionIndicesByEntity = undefined;

    this._unusedLabelIndices = [];
    this._unusedBillboardIndices = [];
    this._unusedPointIndices = [];

    this._previousClusters = [];
    this._previousHeight = undefined;

    this._enabledDirty = false;
    this._pixelRangeDirty = false;
    this._minimumClusterSizeDirty = false;

    return undefined;
  };

  /**
   * A {@link DataSource} implementation which can be used to manually manage a group of entities.
   *
   * @alias CustomDataSource
   * @constructor
   *
   * @param {String} [name] A human-readable name for this instance.
   *
   * @example
   * var dataSource = new Cesium.CustomDataSource('myData');
   *
   * var entity = dataSource.entities.add({
   *    position : Cesium.Cartesian3.fromDegrees(1, 2, 0),
   *    billboard : {
   *        image : 'image.png'
   *    }
   * });
   *
   * viewer.dataSources.add(dataSource);
   */
  function CustomDataSource(name) {
    this._name = name;
    this._clock = undefined;
    this._changed = new Event();
    this._error = new Event();
    this._isLoading = false;
    this._loading = new Event();
    this._entityCollection = new EntityCollection(this);
    this._entityCluster = new EntityCluster();
  }

  Object.defineProperties(CustomDataSource.prototype, {
    /**
     * Gets or sets a human-readable name for this instance.
     * @memberof CustomDataSource.prototype
     * @type {String}
     */
    name: {
      get: function () {
        return this._name;
      },
      set: function (value) {
        if (this._name !== value) {
          this._name = value;
          this._changed.raiseEvent(this);
        }
      },
    },
    /**
     * Gets or sets the clock for this instance.
     * @memberof CustomDataSource.prototype
     * @type {DataSourceClock}
     */
    clock: {
      get: function () {
        return this._clock;
      },
      set: function (value) {
        if (this._clock !== value) {
          this._clock = value;
          this._changed.raiseEvent(this);
        }
      },
    },
    /**
     * Gets the collection of {@link Entity} instances.
     * @memberof CustomDataSource.prototype
     * @type {EntityCollection}
     */
    entities: {
      get: function () {
        return this._entityCollection;
      },
    },
    /**
     * Gets or sets whether the data source is currently loading data.
     * @memberof CustomDataSource.prototype
     * @type {Boolean}
     */
    isLoading: {
      get: function () {
        return this._isLoading;
      },
      set: function (value) {
        DataSource.setLoading(this, value);
      },
    },
    /**
     * Gets an event that will be raised when the underlying data changes.
     * @memberof CustomDataSource.prototype
     * @type {Event}
     */
    changedEvent: {
      get: function () {
        return this._changed;
      },
    },
    /**
     * Gets an event that will be raised if an error is encountered during processing.
     * @memberof CustomDataSource.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._error;
      },
    },
    /**
     * Gets an event that will be raised when the data source either starts or stops loading.
     * @memberof CustomDataSource.prototype
     * @type {Event}
     */
    loadingEvent: {
      get: function () {
        return this._loading;
      },
    },
    /**
     * Gets whether or not this data source should be displayed.
     * @memberof CustomDataSource.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._entityCollection.show;
      },
      set: function (value) {
        this._entityCollection.show = value;
      },
    },

    /**
     * Gets or sets the clustering options for this data source. This object can be shared between multiple data sources.
     *
     * @memberof CustomDataSource.prototype
     * @type {EntityCluster}
     */
    clustering: {
      get: function () {
        return this._entityCluster;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value must be defined.");
        }
        //>>includeEnd('debug');
        this._entityCluster = value;
      },
    },
  });

  /**
   * Updates the data source to the provided time.  This function is optional and
   * is not required to be implemented.  It is provided for data sources which
   * retrieve data based on the current animation time or scene state.
   * If implemented, update will be called by {@link DataSourceDisplay} once a frame.
   *
   * @param {JulianDate} time The simulation time.
   * @returns {Boolean} True if this data source is ready to be displayed at the provided time, false otherwise.
   */
  CustomDataSource.prototype.update = function (time) {
    return true;
  };

  var defaultOffset$2 = Cartesian3.ZERO;

  var offsetScratch$5 = new Cartesian3();
  var positionScratch$7 = new Cartesian3();
  var scratchColor$a = new Color();

  function CylinderGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.length = undefined;
    this.topRadius = undefined;
    this.bottomRadius = undefined;
    this.slices = undefined;
    this.numberOfVerticalLines = undefined;
    this.offsetAttribute = undefined;
  }

  /**
   * A {@link GeometryUpdater} for cylinders.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias CylinderGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function CylinderGeometryUpdater(entity, scene) {
    GeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new CylinderGeometryOptions(entity),
      geometryPropertyName: "cylinder",
      observedPropertyNames: [
        "availability",
        "position",
        "orientation",
        "cylinder",
      ],
    });

    this._onEntityPropertyChanged(entity, "cylinder", entity.cylinder, undefined);
  }

  if (defined(Object.create)) {
    CylinderGeometryUpdater.prototype = Object.create(GeometryUpdater.prototype);
    CylinderGeometryUpdater.prototype.constructor = CylinderGeometryUpdater;
  }

  Object.defineProperties(CylinderGeometryUpdater.prototype, {
    /**
     * Gets the terrain offset property
     * @type {TerrainOffsetProperty}
     * @memberof CylinderGeometryUpdater.prototype
     * @readonly
     * @private
     */
    terrainOffsetProperty: {
      get: function () {
        return this._terrainOffsetProperty;
      },
    },
  });

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  CylinderGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var show = new ShowGeometryInstanceAttribute(
      isAvailable &&
        entity.isShowing &&
        this._showProperty.getValue(time) &&
        this._fillProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );

    var attributes = {
      show: show,
      distanceDisplayCondition: distanceDisplayConditionAttribute,
      color: undefined,
      offset: undefined,
    };
    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$a);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }

    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$2,
          offsetScratch$5
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new CylinderGeometry(this._options),
      modelMatrix: entity.computeModelMatrixForHeightReference(
        time,
        entity.cylinder.heightReference,
        this._options.length * 0.5,
        this._scene.mapProjection.ellipsoid
      ),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  CylinderGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$a
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        distanceDisplayCondition
      ),
      offset: undefined,
    };
    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$2,
          offsetScratch$5
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new CylinderOutlineGeometry(this._options),
      modelMatrix: entity.computeModelMatrixForHeightReference(
        time,
        entity.cylinder.heightReference,
        this._options.length * 0.5,
        this._scene.mapProjection.ellipsoid
      ),
      attributes: attributes,
    });
  };

  CylinderGeometryUpdater.prototype._computeCenter = function (time, result) {
    return Property.getValueOrUndefined(this._entity.position, time, result);
  };

  CylinderGeometryUpdater.prototype._isHidden = function (entity, cylinder) {
    return (
      !defined(entity.position) ||
      !defined(cylinder.length) ||
      !defined(cylinder.topRadius) ||
      !defined(cylinder.bottomRadius) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, cylinder)
    );
  };

  CylinderGeometryUpdater.prototype._isDynamic = function (entity, cylinder) {
    return (
      !entity.position.isConstant || //
      !Property.isConstant(entity.orientation) || //
      !cylinder.length.isConstant || //
      !cylinder.topRadius.isConstant || //
      !cylinder.bottomRadius.isConstant || //
      !Property.isConstant(cylinder.slices) || //
      !Property.isConstant(cylinder.outlineWidth) || //
      !Property.isConstant(cylinder.numberOfVerticalLines)
    );
  };

  CylinderGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    cylinder
  ) {
    var heightReference = Property.getValueOrDefault(
      cylinder.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var options = this._options;
    options.vertexFormat =
      this._materialProperty instanceof ColorMaterialProperty
        ? PerInstanceColorAppearance.VERTEX_FORMAT
        : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.length = cylinder.length.getValue(Iso8601.MINIMUM_VALUE);
    options.topRadius = cylinder.topRadius.getValue(Iso8601.MINIMUM_VALUE);
    options.bottomRadius = cylinder.bottomRadius.getValue(Iso8601.MINIMUM_VALUE);
    options.slices = Property.getValueOrUndefined(
      cylinder.slices,
      Iso8601.MINIMUM_VALUE
    );
    options.numberOfVerticalLines = Property.getValueOrUndefined(
      cylinder.numberOfVerticalLines,
      Iso8601.MINIMUM_VALUE
    );
    options.offsetAttribute =
      heightReference !== HeightReference$1.NONE
        ? GeometryOffsetAttribute$1.ALL
        : undefined;
  };

  CylinderGeometryUpdater.prototype._onEntityPropertyChanged = heightReferenceOnEntityPropertyChanged;

  CylinderGeometryUpdater.DynamicGeometryUpdater = DynamicCylinderGeometryUpdater;

  /**
   * @private
   */
  function DynamicCylinderGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicCylinderGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicCylinderGeometryUpdater.prototype.constructor = DynamicCylinderGeometryUpdater;
  }

  DynamicCylinderGeometryUpdater.prototype._isHidden = function (
    entity,
    cylinder,
    time
  ) {
    var options = this._options;
    var position = Property.getValueOrUndefined(
      entity.position,
      time,
      positionScratch$7
    );
    return (
      !defined(position) ||
      !defined(options.length) ||
      !defined(options.topRadius) || //
      !defined(options.bottomRadius) ||
      DynamicGeometryUpdater.prototype._isHidden.call(
        this,
        entity,
        cylinder,
        time
      )
    );
  };

  DynamicCylinderGeometryUpdater.prototype._setOptions = function (
    entity,
    cylinder,
    time
  ) {
    var heightReference = Property.getValueOrDefault(
      cylinder.heightReference,
      time,
      HeightReference$1.NONE
    );
    var options = this._options;
    options.length = Property.getValueOrUndefined(cylinder.length, time);
    options.topRadius = Property.getValueOrUndefined(cylinder.topRadius, time);
    options.bottomRadius = Property.getValueOrUndefined(
      cylinder.bottomRadius,
      time
    );
    options.slices = Property.getValueOrUndefined(cylinder.slices, time);
    options.numberOfVerticalLines = Property.getValueOrUndefined(
      cylinder.numberOfVerticalLines,
      time
    );
    options.offsetAttribute =
      heightReference !== HeightReference$1.NONE
        ? GeometryOffsetAttribute$1.ALL
        : undefined;
  };

  /**
   * Represents desired clock settings for a particular {@link DataSource}.  These settings may be applied
   * to the {@link Clock} when the DataSource is loaded.
   *
   * @alias DataSourceClock
   * @constructor
   */
  function DataSourceClock() {
    this._definitionChanged = new Event();
    this._startTime = undefined;
    this._stopTime = undefined;
    this._currentTime = undefined;
    this._clockRange = undefined;
    this._clockStep = undefined;
    this._multiplier = undefined;
  }

  Object.defineProperties(DataSourceClock.prototype, {
    /**
     * Gets the event that is raised whenever a new property is assigned.
     * @memberof DataSourceClock.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the desired start time of the clock.
     * See {@link Clock#startTime}.
     * @memberof DataSourceClock.prototype
     * @type {JulianDate}
     */
    startTime: createRawPropertyDescriptor("startTime"),

    /**
     * Gets or sets the desired stop time of the clock.
     * See {@link Clock#stopTime}.
     * @memberof DataSourceClock.prototype
     * @type {JulianDate}
     */
    stopTime: createRawPropertyDescriptor("stopTime"),

    /**
     * Gets or sets the desired current time when this data source is loaded.
     * See {@link Clock#currentTime}.
     * @memberof DataSourceClock.prototype
     * @type {JulianDate}
     */
    currentTime: createRawPropertyDescriptor("currentTime"),

    /**
     * Gets or sets the desired clock range setting.
     * See {@link Clock#clockRange}.
     * @memberof DataSourceClock.prototype
     * @type {ClockRange}
     */
    clockRange: createRawPropertyDescriptor("clockRange"),

    /**
     * Gets or sets the desired clock step setting.
     * See {@link Clock#clockStep}.
     * @memberof DataSourceClock.prototype
     * @type {ClockStep}
     */
    clockStep: createRawPropertyDescriptor("clockStep"),

    /**
     * Gets or sets the desired clock multiplier.
     * See {@link Clock#multiplier}.
     * @memberof DataSourceClock.prototype
     * @type {Number}
     */
    multiplier: createRawPropertyDescriptor("multiplier"),
  });

  /**
   * Duplicates a DataSourceClock instance.
   *
   * @param {DataSourceClock} [result] The object onto which to store the result.
   * @returns {DataSourceClock} The modified result parameter or a new instance if one was not provided.
   */
  DataSourceClock.prototype.clone = function (result) {
    if (!defined(result)) {
      result = new DataSourceClock();
    }
    result.startTime = this.startTime;
    result.stopTime = this.stopTime;
    result.currentTime = this.currentTime;
    result.clockRange = this.clockRange;
    result.clockStep = this.clockStep;
    result.multiplier = this.multiplier;
    return result;
  };

  /**
   * Returns true if this DataSourceClock is equivalent to the other
   *
   * @param {DataSourceClock} other The other DataSourceClock to compare to.
   * @returns {Boolean} <code>true</code> if the DataSourceClocks are equal; otherwise, <code>false</code>.
   */
  DataSourceClock.prototype.equals = function (other) {
    return (
      this === other ||
      (defined(other) &&
        JulianDate.equals(this.startTime, other.startTime) &&
        JulianDate.equals(this.stopTime, other.stopTime) &&
        JulianDate.equals(this.currentTime, other.currentTime) &&
        this.clockRange === other.clockRange &&
        this.clockStep === other.clockStep &&
        this.multiplier === other.multiplier)
    );
  };

  /**
   * Assigns each unassigned property on this object to the value
   * of the same property on the provided source object.
   *
   * @param {DataSourceClock} source The object to be merged into this object.
   */
  DataSourceClock.prototype.merge = function (source) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(source)) {
      throw new DeveloperError("source is required.");
    }
    //>>includeEnd('debug');

    this.startTime = defaultValue(this.startTime, source.startTime);
    this.stopTime = defaultValue(this.stopTime, source.stopTime);
    this.currentTime = defaultValue(this.currentTime, source.currentTime);
    this.clockRange = defaultValue(this.clockRange, source.clockRange);
    this.clockStep = defaultValue(this.clockStep, source.clockStep);
    this.multiplier = defaultValue(this.multiplier, source.multiplier);
  };

  /**
   * Gets the value of this clock instance as a {@link Clock} object.
   *
   * @returns {Clock} The modified result parameter or a new instance if one was not provided.
   */
  DataSourceClock.prototype.getValue = function (result) {
    if (!defined(result)) {
      result = new Clock();
    }
    result.startTime = defaultValue(this.startTime, result.startTime);
    result.stopTime = defaultValue(this.stopTime, result.stopTime);
    result.currentTime = defaultValue(this.currentTime, result.currentTime);
    result.clockRange = defaultValue(this.clockRange, result.clockRange);
    result.multiplier = defaultValue(this.multiplier, result.multiplier);
    result.clockStep = defaultValue(this.clockStep, result.clockStep);
    return result;
  };

  var defaultColor$2 = Color.WHITE;
  var defaultCellAlpha = 0.1;
  var defaultLineCount = new Cartesian2(8, 8);
  var defaultLineOffset = new Cartesian2(0, 0);
  var defaultLineThickness = new Cartesian2(1, 1);

  /**
   * A {@link MaterialProperty} that maps to grid {@link Material} uniforms.
   * @alias GridMaterialProperty
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|Color} [options.color=Color.WHITE] A Property specifying the grid {@link Color}.
   * @param {Property|Number} [options.cellAlpha=0.1] A numeric Property specifying cell alpha values.
   * @param {Property|Cartesian2} [options.lineCount=new Cartesian2(8, 8)] A {@link Cartesian2} Property specifying the number of grid lines along each axis.
   * @param {Property|Cartesian2} [options.lineThickness=new Cartesian2(1.0, 1.0)] A {@link Cartesian2} Property specifying the thickness of grid lines along each axis.
   * @param {Property|Cartesian2} [options.lineOffset=new Cartesian2(0.0, 0.0)] A {@link Cartesian2} Property specifying starting offset of grid lines along each axis.
   *
   * @constructor
   */
  function GridMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._color = undefined;
    this._colorSubscription = undefined;
    this._cellAlpha = undefined;
    this._cellAlphaSubscription = undefined;
    this._lineCount = undefined;
    this._lineCountSubscription = undefined;
    this._lineThickness = undefined;
    this._lineThicknessSubscription = undefined;
    this._lineOffset = undefined;
    this._lineOffsetSubscription = undefined;

    this.color = options.color;
    this.cellAlpha = options.cellAlpha;
    this.lineCount = options.lineCount;
    this.lineThickness = options.lineThickness;
    this.lineOffset = options.lineOffset;
  }

  Object.defineProperties(GridMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof GridMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._color) &&
          Property.isConstant(this._cellAlpha) &&
          Property.isConstant(this._lineCount) &&
          Property.isConstant(this._lineThickness) &&
          Property.isConstant(this._lineOffset)
        );
      },
    },

    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof GridMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the Property specifying the grid {@link Color}.
     * @memberof GridMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the numeric Property specifying cell alpha values.
     * @memberof GridMaterialProperty.prototype
     * @type {Property|undefined}
     * @default 0.1
     */
    cellAlpha: createPropertyDescriptor("cellAlpha"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the number of grid lines along each axis.
     * @memberof GridMaterialProperty.prototype
     * @type {Property|undefined}
     * @default new Cartesian2(8.0, 8.0)
     */
    lineCount: createPropertyDescriptor("lineCount"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the thickness of grid lines along each axis.
     * @memberof GridMaterialProperty.prototype
     * @type {Property|undefined}
     * @default new Cartesian2(1.0, 1.0)
     */
    lineThickness: createPropertyDescriptor("lineThickness"),

    /**
     * Gets or sets the {@link Cartesian2} Property specifying the starting offset of grid lines along each axis.
     * @memberof GridMaterialProperty.prototype
     * @type {Property|undefined}
     * @default new Cartesian2(0.0, 0.0)
     */
    lineOffset: createPropertyDescriptor("lineOffset"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  GridMaterialProperty.prototype.getType = function (time) {
    return "Grid";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  GridMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      defaultColor$2,
      result.color
    );
    result.cellAlpha = Property.getValueOrDefault(
      this._cellAlpha,
      time,
      defaultCellAlpha
    );
    result.lineCount = Property.getValueOrClonedDefault(
      this._lineCount,
      time,
      defaultLineCount,
      result.lineCount
    );
    result.lineThickness = Property.getValueOrClonedDefault(
      this._lineThickness,
      time,
      defaultLineThickness,
      result.lineThickness
    );
    result.lineOffset = Property.getValueOrClonedDefault(
      this._lineOffset,
      time,
      defaultLineOffset,
      result.lineOffset
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  GridMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof GridMaterialProperty && //
      Property.equals(this._color, other._color) && //
      Property.equals(this._cellAlpha, other._cellAlpha) && //
      Property.equals(this._lineCount, other._lineCount) && //
      Property.equals(this._lineThickness, other._lineThickness) && //
        Property.equals(this._lineOffset, other._lineOffset))
    );
  };

  /**
   * A {@link MaterialProperty} that maps to PolylineArrow {@link Material} uniforms.
   *
   * @param {Property|Color} [color=Color.WHITE] The {@link Color} Property to be used.
   *
   * @alias PolylineArrowMaterialProperty
   * @constructor
   */
  function PolylineArrowMaterialProperty(color) {
    this._definitionChanged = new Event();
    this._color = undefined;
    this._colorSubscription = undefined;

    this.color = color;
  }

  Object.defineProperties(PolylineArrowMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof PolylineArrowMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return Property.isConstant(this._color);
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof PolylineArrowMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the {@link Color} {@link Property}.
     * @memberof PolylineArrowMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  PolylineArrowMaterialProperty.prototype.getType = function (time) {
    return "PolylineArrow";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PolylineArrowMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      Color.WHITE,
      result.color
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PolylineArrowMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof PolylineArrowMaterialProperty && //
        Property.equals(this._color, other._color))
    );
  };

  var defaultColor$3 = Color.WHITE;
  var defaultGapColor = Color.TRANSPARENT;
  var defaultDashLength = 16.0;
  var defaultDashPattern = 255.0;

  /**
   * A {@link MaterialProperty} that maps to polyline dash {@link Material} uniforms.
   * @alias PolylineDashMaterialProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|Color} [options.color=Color.WHITE] A Property specifying the {@link Color} of the line.
   * @param {Property|Color} [options.gapColor=Color.TRANSPARENT] A Property specifying the {@link Color} of the gaps in the line.
   * @param {Property|Number} [options.dashLength=16.0] A numeric Property specifying the length of the dash pattern in pixels.
   * @param {Property|Number} [options.dashPattern=255.0] A numeric Property specifying a 16 bit pattern for the dash
   */
  function PolylineDashMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._color = undefined;
    this._colorSubscription = undefined;
    this._gapColor = undefined;
    this._gapColorSubscription = undefined;
    this._dashLength = undefined;
    this._dashLengthSubscription = undefined;
    this._dashPattern = undefined;
    this._dashPatternSubscription = undefined;

    this.color = options.color;
    this.gapColor = options.gapColor;
    this.dashLength = options.dashLength;
    this.dashPattern = options.dashPattern;
  }

  Object.defineProperties(PolylineDashMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof PolylineDashMaterialProperty.prototype
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._color) &&
          Property.isConstant(this._gapColor) &&
          Property.isConstant(this._dashLength) &&
          Property.isConstant(this._dashPattern)
        );
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof PolylineDashMaterialProperty.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the Property specifying the {@link Color} of the line.
     * @memberof PolylineDashMaterialProperty.prototype
     * @type {Property|undefined}
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the gaps in the line.
     * @memberof PolylineDashMaterialProperty.prototype
     * @type {Property|undefined}
     */
    gapColor: createPropertyDescriptor("gapColor"),

    /**
     * Gets or sets the numeric Property specifying the length of a dash cycle
     * @memberof PolylineDashMaterialProperty.prototype
     * @type {Property|undefined}
     */
    dashLength: createPropertyDescriptor("dashLength"),

    /**
     * Gets or sets the numeric Property specifying a dash pattern
     * @memberof PolylineDashMaterialProperty.prototype
     * @type {Property|undefined}
     */
    dashPattern: createPropertyDescriptor("dashPattern"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  PolylineDashMaterialProperty.prototype.getType = function (time) {
    return "PolylineDash";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PolylineDashMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      defaultColor$3,
      result.color
    );
    result.gapColor = Property.getValueOrClonedDefault(
      this._gapColor,
      time,
      defaultGapColor,
      result.gapColor
    );
    result.dashLength = Property.getValueOrDefault(
      this._dashLength,
      time,
      defaultDashLength,
      result.dashLength
    );
    result.dashPattern = Property.getValueOrDefault(
      this._dashPattern,
      time,
      defaultDashPattern,
      result.dashPattern
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PolylineDashMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof PolylineDashMaterialProperty &&
        Property.equals(this._color, other._color) &&
        Property.equals(this._gapColor, other._gapColor) &&
        Property.equals(this._dashLength, other._dashLength) &&
        Property.equals(this._dashPattern, other._dashPattern))
    );
  };

  var defaultColor$4 = Color.WHITE;
  var defaultGlowPower = 0.25;
  var defaultTaperPower = 1.0;

  /**
   * A {@link MaterialProperty} that maps to polyline glow {@link Material} uniforms.
   * @alias PolylineGlowMaterialProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|Color} [options.color=Color.WHITE] A Property specifying the {@link Color} of the line.
   * @param {Property|Number} [options.glowPower=0.25] A numeric Property specifying the strength of the glow, as a percentage of the total line width.
   * @param {Property|Number} [options.taperPower=1.0] A numeric Property specifying the strength of the tapering effect, as a percentage of the total line length.  If 1.0 or higher, no taper effect is used.
   */
  function PolylineGlowMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._color = undefined;
    this._colorSubscription = undefined;
    this._glowPower = undefined;
    this._glowPowerSubscription = undefined;
    this._taperPower = undefined;
    this._taperPowerSubscription = undefined;

    this.color = options.color;
    this.glowPower = options.glowPower;
    this.taperPower = options.taperPower;
  }

  Object.defineProperties(PolylineGlowMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof PolylineGlowMaterialProperty.prototype
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._color) && Property.isConstant(this._glow)
        );
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof PolylineGlowMaterialProperty.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the Property specifying the {@link Color} of the line.
     * @memberof PolylineGlowMaterialProperty.prototype
     * @type {Property|undefined}
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the numeric Property specifying the strength of the glow, as a percentage of the total line width (less than 1.0).
     * @memberof PolylineGlowMaterialProperty.prototype
     * @type {Property|undefined}
     */
    glowPower: createPropertyDescriptor("glowPower"),

    /**
     * Gets or sets the numeric Property specifying the strength of the tapering effect, as a percentage of the total line length.  If 1.0 or higher, no taper effect is used.
     * @memberof PolylineGlowMaterialProperty.prototype
     * @type {Property|undefined}
     */
    taperPower: createPropertyDescriptor("taperPower"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  PolylineGlowMaterialProperty.prototype.getType = function (time) {
    return "PolylineGlow";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PolylineGlowMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      defaultColor$4,
      result.color
    );
    result.glowPower = Property.getValueOrDefault(
      this._glowPower,
      time,
      defaultGlowPower,
      result.glowPower
    );
    result.taperPower = Property.getValueOrDefault(
      this._taperPower,
      time,
      defaultTaperPower,
      result.taperPower
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PolylineGlowMaterialProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof PolylineGlowMaterialProperty &&
        Property.equals(this._color, other._color) &&
        Property.equals(this._glowPower, other._glowPower) &&
        Property.equals(this._taperPower, other._taperPower))
    );
  };

  var defaultColor$5 = Color.WHITE;
  var defaultOutlineColor$1 = Color.BLACK;
  var defaultOutlineWidth = 1.0;

  /**
   * A {@link MaterialProperty} that maps to polyline outline {@link Material} uniforms.
   * @alias PolylineOutlineMaterialProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|Color} [options.color=Color.WHITE] A Property specifying the {@link Color} of the line.
   * @param {Property|Color} [options.outlineColor=Color.BLACK] A Property specifying the {@link Color} of the outline.
   * @param {Property|Number} [options.outlineWidth=1.0] A numeric Property specifying the width of the outline, in pixels.
   */
  function PolylineOutlineMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._color = undefined;
    this._colorSubscription = undefined;
    this._outlineColor = undefined;
    this._outlineColorSubscription = undefined;
    this._outlineWidth = undefined;
    this._outlineWidthSubscription = undefined;

    this.color = options.color;
    this.outlineColor = options.outlineColor;
    this.outlineWidth = options.outlineWidth;
  }

  Object.defineProperties(PolylineOutlineMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof PolylineOutlineMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._color) &&
          Property.isConstant(this._outlineColor) &&
          Property.isConstant(this._outlineWidth)
        );
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof PolylineOutlineMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the Property specifying the {@link Color} of the line.
     * @memberof PolylineOutlineMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    color: createPropertyDescriptor("color"),

    /**
     * Gets or sets the Property specifying the {@link Color} of the outline.
     * @memberof PolylineOutlineMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    outlineColor: createPropertyDescriptor("outlineColor"),

    /**
     * Gets or sets the numeric Property specifying the width of the outline.
     * @memberof PolylineOutlineMaterialProperty.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    outlineWidth: createPropertyDescriptor("outlineWidth"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  PolylineOutlineMaterialProperty.prototype.getType = function (time) {
    return "PolylineOutline";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PolylineOutlineMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.color = Property.getValueOrClonedDefault(
      this._color,
      time,
      defaultColor$5,
      result.color
    );
    result.outlineColor = Property.getValueOrClonedDefault(
      this._outlineColor,
      time,
      defaultOutlineColor$1,
      result.outlineColor
    );
    result.outlineWidth = Property.getValueOrDefault(
      this._outlineWidth,
      time,
      defaultOutlineWidth
    );
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PolylineOutlineMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof PolylineOutlineMaterialProperty && //
      Property.equals(this._color, other._color) && //
      Property.equals(this._outlineColor, other._outlineColor) && //
        Property.equals(this._outlineWidth, other._outlineWidth))
    );
  };

  /**
   * A {@link Property} whose value is an array whose items are the computed value
   * of other PositionProperty instances.
   *
   * @alias PositionPropertyArray
   * @constructor
   *
   * @param {Property[]} [value] An array of Property instances.
   * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
   */
  function PositionPropertyArray(value, referenceFrame) {
    this._value = undefined;
    this._definitionChanged = new Event();
    this._eventHelper = new EventHelper();
    this._referenceFrame = defaultValue(referenceFrame, ReferenceFrame$1.FIXED);
    this.setValue(value);
  }

  Object.defineProperties(PositionPropertyArray.prototype, {
    /**
     * Gets a value indicating if this property is constant.  This property
     * is considered constant if all property items in the array are constant.
     * @memberof PositionPropertyArray.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        var value = this._value;
        if (!defined(value)) {
          return true;
        }

        var length = value.length;
        for (var i = 0; i < length; i++) {
          if (!Property.isConstant(value[i])) {
            return false;
          }
        }
        return true;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value or one of the properties in the array also changes.
     * @memberof PositionPropertyArray.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the reference frame in which the position is defined.
     * @memberof PositionPropertyArray.prototype
     * @type {ReferenceFrame}
     * @default ReferenceFrame.FIXED;
     */
    referenceFrame: {
      get: function () {
        return this._referenceFrame;
      },
    },
  });

  /**
   * Gets the value of the property.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Cartesian3[]} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3[]} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PositionPropertyArray.prototype.getValue = function (time, result) {
    return this.getValueInReferenceFrame(time, ReferenceFrame$1.FIXED, result);
  };

  /**
   * Gets the value of the property at the provided time and in the provided reference frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3[]} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3[]} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  PositionPropertyArray.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    if (!defined(referenceFrame)) {
      throw new DeveloperError("referenceFrame is required.");
    }
    //>>includeEnd('debug');

    var value = this._value;
    if (!defined(value)) {
      return undefined;
    }

    var length = value.length;
    if (!defined(result)) {
      result = new Array(length);
    }
    var i = 0;
    var x = 0;
    while (i < length) {
      var property = value[i];
      var itemValue = property.getValueInReferenceFrame(
        time,
        referenceFrame,
        result[i]
      );
      if (defined(itemValue)) {
        result[x] = itemValue;
        x++;
      }
      i++;
    }
    result.length = x;
    return result;
  };

  /**
   * Sets the value of the property.
   *
   * @param {Property[]} value An array of Property instances.
   */
  PositionPropertyArray.prototype.setValue = function (value) {
    var eventHelper = this._eventHelper;
    eventHelper.removeAll();

    if (defined(value)) {
      this._value = value.slice();
      var length = value.length;
      for (var i = 0; i < length; i++) {
        var property = value[i];
        if (defined(property)) {
          eventHelper.add(
            property.definitionChanged,
            PositionPropertyArray.prototype._raiseDefinitionChanged,
            this
          );
        }
      }
    } else {
      this._value = undefined;
    }
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PositionPropertyArray.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof PositionPropertyArray && //
      this._referenceFrame === other._referenceFrame && //
        Property.arrayEquals(this._value, other._value))
    );
  };

  PositionPropertyArray.prototype._raiseDefinitionChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * A {@link Property} whose value is an array whose items are the computed value
   * of other property instances.
   *
   * @alias PropertyArray
   * @constructor
   *
   * @param {Property[]} [value] An array of Property instances.
   */
  function PropertyArray(value) {
    this._value = undefined;
    this._definitionChanged = new Event();
    this._eventHelper = new EventHelper();
    this.setValue(value);
  }

  Object.defineProperties(PropertyArray.prototype, {
    /**
     * Gets a value indicating if this property is constant.  This property
     * is considered constant if all property items in the array are constant.
     * @memberof PropertyArray.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        var value = this._value;
        if (!defined(value)) {
          return true;
        }
        var length = value.length;
        for (var i = 0; i < length; i++) {
          if (!Property.isConstant(value[i])) {
            return false;
          }
        }
        return true;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value or one of the properties in the array also changes.
     * @memberof PropertyArray.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
  });

  /**
   * Gets the value of the property.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object[]} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object[]} The modified result parameter, which is an array of values produced by evaluating each of the contained properties at the given time or a new instance if the result parameter was not supplied.
   */
  PropertyArray.prototype.getValue = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var value = this._value;
    if (!defined(value)) {
      return undefined;
    }

    var length = value.length;
    if (!defined(result)) {
      result = new Array(length);
    }
    var i = 0;
    var x = 0;
    while (i < length) {
      var property = this._value[i];
      var itemValue = property.getValue(time, result[i]);
      if (defined(itemValue)) {
        result[x] = itemValue;
        x++;
      }
      i++;
    }
    result.length = x;
    return result;
  };

  /**
   * Sets the value of the property.
   *
   * @param {Property[]} value An array of Property instances.
   */
  PropertyArray.prototype.setValue = function (value) {
    var eventHelper = this._eventHelper;
    eventHelper.removeAll();

    if (defined(value)) {
      this._value = value.slice();
      var length = value.length;
      for (var i = 0; i < length; i++) {
        var property = value[i];
        if (defined(property)) {
          eventHelper.add(
            property.definitionChanged,
            PropertyArray.prototype._raiseDefinitionChanged,
            this
          );
        }
      }
    } else {
      this._value = undefined;
    }
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  PropertyArray.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof PropertyArray && //
        Property.arrayEquals(this._value, other._value))
    );
  };

  PropertyArray.prototype._raiseDefinitionChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  function resolve$1(that) {
    var targetProperty = that._targetProperty;

    if (!defined(targetProperty)) {
      var targetEntity = that._targetEntity;

      if (!defined(targetEntity)) {
        targetEntity = that._targetCollection.getById(that._targetId);

        if (!defined(targetEntity)) {
          // target entity not found
          that._targetEntity = that._targetProperty = undefined;
          return;
        }

        // target entity was found. listen for changes to entity definition
        targetEntity.definitionChanged.addEventListener(
          ReferenceProperty.prototype._onTargetEntityDefinitionChanged,
          that
        );
        that._targetEntity = targetEntity;
      }

      // walk the list of property names and resolve properties
      var targetPropertyNames = that._targetPropertyNames;
      targetProperty = that._targetEntity;
      for (
        var i = 0, len = targetPropertyNames.length;
        i < len && defined(targetProperty);
        ++i
      ) {
        targetProperty = targetProperty[targetPropertyNames[i]];
      }

      // target property may or may not be defined, depending on if it was found
      that._targetProperty = targetProperty;
    }

    return targetProperty;
  }

  /**
   * A {@link Property} which transparently links to another property on a provided object.
   *
   * @alias ReferenceProperty
   * @constructor
   *
   * @param {EntityCollection} targetCollection The entity collection which will be used to resolve the reference.
   * @param {String} targetId The id of the entity which is being referenced.
   * @param {String[]} targetPropertyNames The names of the property on the target entity which we will use.
   *
   * @example
   * var collection = new Cesium.EntityCollection();
   *
   * //Create a new entity and assign a billboard scale.
   * var object1 = new Cesium.Entity({id:'object1'});
   * object1.billboard = new Cesium.BillboardGraphics();
   * object1.billboard.scale = new Cesium.ConstantProperty(2.0);
   * collection.add(object1);
   *
   * //Create a second entity and reference the scale from the first one.
   * var object2 = new Cesium.Entity({id:'object2'});
   * object2.model = new Cesium.ModelGraphics();
   * object2.model.scale = new Cesium.ReferenceProperty(collection, 'object1', ['billboard', 'scale']);
   * collection.add(object2);
   *
   * //Create a third object, but use the fromString helper function.
   * var object3 = new Cesium.Entity({id:'object3'});
   * object3.billboard = new Cesium.BillboardGraphics();
   * object3.billboard.scale = Cesium.ReferenceProperty.fromString(collection, 'object1#billboard.scale');
   * collection.add(object3);
   *
   * //You can refer to an entity with a # or . in id and property names by escaping them.
   * var object4 = new Cesium.Entity({id:'#object.4'});
   * object4.billboard = new Cesium.BillboardGraphics();
   * object4.billboard.scale = new Cesium.ConstantProperty(2.0);
   * collection.add(object4);
   *
   * var object5 = new Cesium.Entity({id:'object5'});
   * object5.billboard = new Cesium.BillboardGraphics();
   * object5.billboard.scale = Cesium.ReferenceProperty.fromString(collection, '\\#object\\.4#billboard.scale');
   * collection.add(object5);
   */
  function ReferenceProperty(targetCollection, targetId, targetPropertyNames) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(targetCollection)) {
      throw new DeveloperError("targetCollection is required.");
    }
    if (!defined(targetId) || targetId === "") {
      throw new DeveloperError("targetId is required.");
    }
    if (!defined(targetPropertyNames) || targetPropertyNames.length === 0) {
      throw new DeveloperError("targetPropertyNames is required.");
    }
    for (var i = 0; i < targetPropertyNames.length; i++) {
      var item = targetPropertyNames[i];
      if (!defined(item) || item === "") {
        throw new DeveloperError("reference contains invalid properties.");
      }
    }
    //>>includeEnd('debug');

    this._targetCollection = targetCollection;
    this._targetId = targetId;
    this._targetPropertyNames = targetPropertyNames;
    this._targetProperty = undefined;
    this._targetEntity = undefined;
    this._definitionChanged = new Event();

    targetCollection.collectionChanged.addEventListener(
      ReferenceProperty.prototype._onCollectionChanged,
      this
    );
  }

  Object.defineProperties(ReferenceProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.
     * @memberof ReferenceProperty.prototype
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return Property.isConstant(resolve$1(this));
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever the referenced property's definition is changed.
     * @memberof ReferenceProperty.prototype
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the reference frame that the position is defined in.
     * This property is only valid if the referenced property is a {@link PositionProperty}.
     * @memberof ReferenceProperty.prototype
     * @type {ReferenceFrame}
     * @readonly
     */
    referenceFrame: {
      get: function () {
        var target = resolve$1(this);
        return defined(target) ? target.referenceFrame : undefined;
      },
    },
    /**
     * Gets the id of the entity being referenced.
     * @memberof ReferenceProperty.prototype
     * @type {String}
     * @readonly
     */
    targetId: {
      get: function () {
        return this._targetId;
      },
    },
    /**
     * Gets the collection containing the entity being referenced.
     * @memberof ReferenceProperty.prototype
     * @type {EntityCollection}
     * @readonly
     */
    targetCollection: {
      get: function () {
        return this._targetCollection;
      },
    },
    /**
     * Gets the array of property names used to retrieve the referenced property.
     * @memberof ReferenceProperty.prototype
     * @type {String[]}
     * @readonly
     */
    targetPropertyNames: {
      get: function () {
        return this._targetPropertyNames;
      },
    },
    /**
     * Gets the resolved instance of the underlying referenced property.
     * @memberof ReferenceProperty.prototype
     * @type {Property|undefined}
     * @readonly
     */
    resolvedProperty: {
      get: function () {
        return resolve$1(this);
      },
    },
  });

  /**
   * Creates a new instance given the entity collection that will
   * be used to resolve it and a string indicating the target entity id and property.
   * The format of the string is "objectId#foo.bar", where # separates the id from
   * property path and . separates sub-properties.  If the reference identifier or
   * or any sub-properties contains a # . or \ they must be escaped.
   *
   * @param {EntityCollection} targetCollection
   * @param {String} referenceString
   * @returns {ReferenceProperty} A new instance of ReferenceProperty.
   *
   * @exception {DeveloperError} invalid referenceString.
   */
  ReferenceProperty.fromString = function (targetCollection, referenceString) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(targetCollection)) {
      throw new DeveloperError("targetCollection is required.");
    }
    if (!defined(referenceString)) {
      throw new DeveloperError("referenceString is required.");
    }
    //>>includeEnd('debug');

    var identifier;
    var values = [];

    var inIdentifier = true;
    var isEscaped = false;
    var token = "";
    for (var i = 0; i < referenceString.length; ++i) {
      var c = referenceString.charAt(i);

      if (isEscaped) {
        token += c;
        isEscaped = false;
      } else if (c === "\\") {
        isEscaped = true;
      } else if (inIdentifier && c === "#") {
        identifier = token;
        inIdentifier = false;
        token = "";
      } else if (!inIdentifier && c === ".") {
        values.push(token);
        token = "";
      } else {
        token += c;
      }
    }
    values.push(token);

    return new ReferenceProperty(targetCollection, identifier, values);
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ReferenceProperty.prototype.getValue = function (time, result) {
    var target = resolve$1(this);
    return defined(target) ? target.getValue(time, result) : undefined;
  };

  /**
   * Gets the value of the property at the provided time and in the provided reference frame.
   * This method is only valid if the property being referenced is a {@link PositionProperty}.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  ReferenceProperty.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    var target = resolve$1(this);
    return defined(target)
      ? target.getValueInReferenceFrame(time, referenceFrame, result)
      : undefined;
  };

  /**
   * Gets the {@link Material} type at the provided time.
   * This method is only valid if the property being referenced is a {@link MaterialProperty}.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  ReferenceProperty.prototype.getType = function (time) {
    var target = resolve$1(this);
    return defined(target) ? target.getType(time) : undefined;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  ReferenceProperty.prototype.equals = function (other) {
    if (this === other) {
      return true;
    }

    var names = this._targetPropertyNames;
    var otherNames = other._targetPropertyNames;

    if (
      this._targetCollection !== other._targetCollection || //
      this._targetId !== other._targetId || //
      names.length !== otherNames.length
    ) {
      return false;
    }

    var length = this._targetPropertyNames.length;
    for (var i = 0; i < length; i++) {
      if (names[i] !== otherNames[i]) {
        return false;
      }
    }

    return true;
  };

  ReferenceProperty.prototype._onTargetEntityDefinitionChanged = function (
    targetEntity,
    name,
    value,
    oldValue
  ) {
    if (defined(this._targetProperty) && this._targetPropertyNames[0] === name) {
      this._targetProperty = undefined;
      this._definitionChanged.raiseEvent(this);
    }
  };

  ReferenceProperty.prototype._onCollectionChanged = function (
    collection,
    added,
    removed
  ) {
    var targetEntity = this._targetEntity;
    if (defined(targetEntity) && removed.indexOf(targetEntity) !== -1) {
      targetEntity.definitionChanged.removeEventListener(
        ReferenceProperty.prototype._onTargetEntityDefinitionChanged,
        this
      );
      this._targetEntity = this._targetProperty = undefined;
    } else if (!defined(targetEntity)) {
      targetEntity = resolve$1(this);
      if (defined(targetEntity)) {
        this._definitionChanged.raiseEvent(this);
      }
    }
  };

  /**
   * Represents a {@link Packable} number that always interpolates values
   * towards the shortest angle of rotation. This object is never used directly
   * but is instead passed to the constructor of {@link SampledProperty}
   * in order to represent a two-dimensional angle of rotation.
   *
   * @interface Rotation
   *
   *
   * @example
   * var time1 = Cesium.JulianDate.fromIso8601('2010-05-07T00:00:00');
   * var time2 = Cesium.JulianDate.fromIso8601('2010-05-07T00:01:00');
   * var time3 = Cesium.JulianDate.fromIso8601('2010-05-07T00:02:00');
   *
   * var property = new Cesium.SampledProperty(Cesium.Rotation);
   * property.addSample(time1, 0);
   * property.addSample(time3, Cesium.Math.toRadians(350));
   *
   * //Getting the value at time2 will equal 355 degrees instead
   * //of 175 degrees (which is what you get if you construct
   * //a SampledProperty(Number) instead.  Note, the actual
   * //return value is in radians, not degrees.
   * property.getValue(time2);
   *
   * @see PackableForInterpolation
   */
  var Rotation = {
    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    packedLength: 1,

    /**
     * Stores the provided instance into the provided array.
     *
     * @param {Rotation} value The value to pack.
     * @param {Number[]} array The array to pack into.
     * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
     *
     * @returns {Number[]} The array that was packed into
     */
    pack: function (value, array, startingIndex) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(value)) {
        throw new DeveloperError("value is required");
      }

      if (!defined(array)) {
        throw new DeveloperError("array is required");
      }
      //>>includeEnd('debug');

      startingIndex = defaultValue(startingIndex, 0);
      array[startingIndex] = value;

      return array;
    },

    /**
     * Retrieves an instance from a packed array.
     *
     * @param {Number[]} array The packed array.
     * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
     * @param {Rotation} [result] The object into which to store the result.
     * @returns {Rotation} The modified result parameter or a new Rotation instance if one was not provided.
     */
    unpack: function (array, startingIndex, result) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(array)) {
        throw new DeveloperError("array is required");
      }
      //>>includeEnd('debug');

      startingIndex = defaultValue(startingIndex, 0);
      return array[startingIndex];
    },

    /**
     * Converts a packed array into a form suitable for interpolation.
     *
     * @param {Number[]} packedArray The packed array.
     * @param {Number} [startingIndex=0] The index of the first element to be converted.
     * @param {Number} [lastIndex=packedArray.length] The index of the last element to be converted.
     * @param {Number[]} [result] The object into which to store the result.
     */
    convertPackedArrayForInterpolation: function (
      packedArray,
      startingIndex,
      lastIndex,
      result
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(packedArray)) {
        throw new DeveloperError("packedArray is required");
      }
      //>>includeEnd('debug');

      if (!defined(result)) {
        result = [];
      }

      startingIndex = defaultValue(startingIndex, 0);
      lastIndex = defaultValue(lastIndex, packedArray.length);

      var previousValue;
      for (var i = 0, len = lastIndex - startingIndex + 1; i < len; i++) {
        var value = packedArray[startingIndex + i];
        if (i === 0 || Math.abs(previousValue - value) < Math.PI) {
          result[i] = value;
        } else {
          result[i] = value - CesiumMath.TWO_PI;
        }
        previousValue = value;
      }
    },

    /**
     * Retrieves an instance from a packed array converted with {@link Rotation.convertPackedArrayForInterpolation}.
     *
     * @param {Number[]} array The array previously packed for interpolation.
     * @param {Number[]} sourceArray The original packed array.
     * @param {Number} [firstIndex=0] The firstIndex used to convert the array.
     * @param {Number} [lastIndex=packedArray.length] The lastIndex used to convert the array.
     * @param {Rotation} [result] The object into which to store the result.
     * @returns {Rotation} The modified result parameter or a new Rotation instance if one was not provided.
     */
    unpackInterpolationResult: function (
      array,
      sourceArray,
      firstIndex,
      lastIndex,
      result
    ) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(array)) {
        throw new DeveloperError("array is required");
      }
      if (!defined(sourceArray)) {
        throw new DeveloperError("sourceArray is required");
      }
      //>>includeEnd('debug');

      result = array[0];
      if (result < 0) {
        return result + CesiumMath.TWO_PI;
      }
      return result;
    },
  };

  var PackableNumber = {
    packedLength: 1,
    pack: function (value, array, startingIndex) {
      startingIndex = defaultValue(startingIndex, 0);
      array[startingIndex] = value;
    },
    unpack: function (array, startingIndex, result) {
      startingIndex = defaultValue(startingIndex, 0);
      return array[startingIndex];
    },
  };

  //We can't use splice for inserting new elements because function apply can't handle
  //a huge number of arguments.  See https://code.google.com/p/chromium/issues/detail?id=56588
  function arrayInsert(array, startIndex, items) {
    var i;
    var arrayLength = array.length;
    var itemsLength = items.length;
    var newLength = arrayLength + itemsLength;

    array.length = newLength;
    if (arrayLength !== startIndex) {
      var q = arrayLength - 1;
      for (i = newLength - 1; i >= startIndex; i--) {
        array[i] = array[q--];
      }
    }

    for (i = 0; i < itemsLength; i++) {
      array[startIndex++] = items[i];
    }
  }

  function convertDate(date, epoch) {
    if (date instanceof JulianDate) {
      return date;
    }
    if (typeof date === "string") {
      return JulianDate.fromIso8601(date);
    }
    return JulianDate.addSeconds(epoch, date, new JulianDate());
  }

  var timesSpliceArgs = [];
  var valuesSpliceArgs = [];

  function mergeNewSamples(epoch, times, values, newData, packedLength) {
    var newDataIndex = 0;
    var i;
    var prevItem;
    var timesInsertionPoint;
    var valuesInsertionPoint;
    var currentTime;
    var nextTime;

    while (newDataIndex < newData.length) {
      currentTime = convertDate(newData[newDataIndex], epoch);
      timesInsertionPoint = binarySearch(times, currentTime, JulianDate.compare);
      var timesSpliceArgsCount = 0;
      var valuesSpliceArgsCount = 0;

      if (timesInsertionPoint < 0) {
        //Doesn't exist, insert as many additional values as we can.
        timesInsertionPoint = ~timesInsertionPoint;

        valuesInsertionPoint = timesInsertionPoint * packedLength;
        prevItem = undefined;
        nextTime = times[timesInsertionPoint];
        while (newDataIndex < newData.length) {
          currentTime = convertDate(newData[newDataIndex], epoch);
          if (
            (defined(prevItem) &&
              JulianDate.compare(prevItem, currentTime) >= 0) ||
            (defined(nextTime) && JulianDate.compare(currentTime, nextTime) >= 0)
          ) {
            break;
          }
          timesSpliceArgs[timesSpliceArgsCount++] = currentTime;
          newDataIndex = newDataIndex + 1;
          for (i = 0; i < packedLength; i++) {
            valuesSpliceArgs[valuesSpliceArgsCount++] = newData[newDataIndex];
            newDataIndex = newDataIndex + 1;
          }
          prevItem = currentTime;
        }

        if (timesSpliceArgsCount > 0) {
          valuesSpliceArgs.length = valuesSpliceArgsCount;
          arrayInsert(values, valuesInsertionPoint, valuesSpliceArgs);

          timesSpliceArgs.length = timesSpliceArgsCount;
          arrayInsert(times, timesInsertionPoint, timesSpliceArgs);
        }
      } else {
        //Found an exact match
        for (i = 0; i < packedLength; i++) {
          newDataIndex++;
          values[timesInsertionPoint * packedLength + i] = newData[newDataIndex];
        }
        newDataIndex++;
      }
    }
  }

  /**
   * A {@link Property} whose value is interpolated for a given time from the
   * provided set of samples and specified interpolation algorithm and degree.
   * @alias SampledProperty
   * @constructor
   *
   * @param {Number|Packable} type The type of property.
   * @param {Packable[]} [derivativeTypes] When supplied, indicates that samples will contain derivative information of the specified types.
   *
   *
   * @example
   * //Create a linearly interpolated Cartesian2
   * var property = new Cesium.SampledProperty(Cesium.Cartesian2);
   *
   * //Populate it with data
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:00:00.00Z'), new Cesium.Cartesian2(0, 0));
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-02T00:00:00.00Z'), new Cesium.Cartesian2(4, 7));
   *
   * //Retrieve an interpolated value
   * var result = property.getValue(Cesium.JulianDate.fromIso8601('2012-08-01T12:00:00.00Z'));
   *
   * @example
   * //Create a simple numeric SampledProperty that uses third degree Hermite Polynomial Approximation
   * var property = new Cesium.SampledProperty(Number);
   * property.setInterpolationOptions({
   *     interpolationDegree : 3,
   *     interpolationAlgorithm : Cesium.HermitePolynomialApproximation
   * });
   *
   * //Populate it with data
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:00:00.00Z'), 1.0);
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:01:00.00Z'), 6.0);
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:02:00.00Z'), 12.0);
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:03:30.00Z'), 5.0);
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:06:30.00Z'), 2.0);
   *
   * //Samples can be added in any order.
   * property.addSample(Cesium.JulianDate.fromIso8601('2012-08-01T00:00:30.00Z'), 6.2);
   *
   * //Retrieve an interpolated value
   * var result = property.getValue(Cesium.JulianDate.fromIso8601('2012-08-01T00:02:34.00Z'));
   *
   * @see SampledPositionProperty
   */
  function SampledProperty(type, derivativeTypes) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("type", type);
    //>>includeEnd('debug');

    var innerType = type;
    if (innerType === Number) {
      innerType = PackableNumber;
    }
    var packedLength = innerType.packedLength;
    var packedInterpolationLength = defaultValue(
      innerType.packedInterpolationLength,
      packedLength
    );

    var inputOrder = 0;
    var innerDerivativeTypes;
    if (defined(derivativeTypes)) {
      var length = derivativeTypes.length;
      innerDerivativeTypes = new Array(length);
      for (var i = 0; i < length; i++) {
        var derivativeType = derivativeTypes[i];
        if (derivativeType === Number) {
          derivativeType = PackableNumber;
        }
        var derivativePackedLength = derivativeType.packedLength;
        packedLength += derivativePackedLength;
        packedInterpolationLength += defaultValue(
          derivativeType.packedInterpolationLength,
          derivativePackedLength
        );
        innerDerivativeTypes[i] = derivativeType;
      }
      inputOrder = length;
    }

    this._type = type;
    this._innerType = innerType;
    this._interpolationDegree = 1;
    this._interpolationAlgorithm = LinearApproximation;
    this._numberOfPoints = 0;
    this._times = [];
    this._values = [];
    this._xTable = [];
    this._yTable = [];
    this._packedLength = packedLength;
    this._packedInterpolationLength = packedInterpolationLength;
    this._updateTableLength = true;
    this._interpolationResult = new Array(packedInterpolationLength);
    this._definitionChanged = new Event();
    this._derivativeTypes = derivativeTypes;
    this._innerDerivativeTypes = innerDerivativeTypes;
    this._inputOrder = inputOrder;
    this._forwardExtrapolationType = ExtrapolationType$1.NONE;
    this._forwardExtrapolationDuration = 0;
    this._backwardExtrapolationType = ExtrapolationType$1.NONE;
    this._backwardExtrapolationDuration = 0;
  }

  Object.defineProperties(SampledProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof SampledProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._values.length === 0;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof SampledProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the type of property.
     * @memberof SampledProperty.prototype
     * @type {*}
     */
    type: {
      get: function () {
        return this._type;
      },
    },
    /**
     * Gets the derivative types used by this property.
     * @memberof SampledProperty.prototype
     * @type {Packable[]}
     */
    derivativeTypes: {
      get: function () {
        return this._derivativeTypes;
      },
    },
    /**
     * Gets the degree of interpolation to perform when retrieving a value.
     * @memberof SampledProperty.prototype
     * @type {Number}
     * @default 1
     */
    interpolationDegree: {
      get: function () {
        return this._interpolationDegree;
      },
    },
    /**
     * Gets the interpolation algorithm to use when retrieving a value.
     * @memberof SampledProperty.prototype
     * @type {InterpolationAlgorithm}
     * @default LinearApproximation
     */
    interpolationAlgorithm: {
      get: function () {
        return this._interpolationAlgorithm;
      },
    },
    /**
     * Gets or sets the type of extrapolation to perform when a value
     * is requested at a time after any available samples.
     * @memberof SampledProperty.prototype
     * @type {ExtrapolationType}
     * @default ExtrapolationType.NONE
     */
    forwardExtrapolationType: {
      get: function () {
        return this._forwardExtrapolationType;
      },
      set: function (value) {
        if (this._forwardExtrapolationType !== value) {
          this._forwardExtrapolationType = value;
          this._definitionChanged.raiseEvent(this);
        }
      },
    },
    /**
     * Gets or sets the amount of time to extrapolate forward before
     * the property becomes undefined.  A value of 0 will extrapolate forever.
     * @memberof SampledProperty.prototype
     * @type {Number}
     * @default 0
     */
    forwardExtrapolationDuration: {
      get: function () {
        return this._forwardExtrapolationDuration;
      },
      set: function (value) {
        if (this._forwardExtrapolationDuration !== value) {
          this._forwardExtrapolationDuration = value;
          this._definitionChanged.raiseEvent(this);
        }
      },
    },
    /**
     * Gets or sets the type of extrapolation to perform when a value
     * is requested at a time before any available samples.
     * @memberof SampledProperty.prototype
     * @type {ExtrapolationType}
     * @default ExtrapolationType.NONE
     */
    backwardExtrapolationType: {
      get: function () {
        return this._backwardExtrapolationType;
      },
      set: function (value) {
        if (this._backwardExtrapolationType !== value) {
          this._backwardExtrapolationType = value;
          this._definitionChanged.raiseEvent(this);
        }
      },
    },
    /**
     * Gets or sets the amount of time to extrapolate backward
     * before the property becomes undefined.  A value of 0 will extrapolate forever.
     * @memberof SampledProperty.prototype
     * @type {Number}
     * @default 0
     */
    backwardExtrapolationDuration: {
      get: function () {
        return this._backwardExtrapolationDuration;
      },
      set: function (value) {
        if (this._backwardExtrapolationDuration !== value) {
          this._backwardExtrapolationDuration = value;
          this._definitionChanged.raiseEvent(this);
        }
      },
    },
  });

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  SampledProperty.prototype.getValue = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var times = this._times;
    var timesLength = times.length;
    if (timesLength === 0) {
      return undefined;
    }

    var timeout;
    var innerType = this._innerType;
    var values = this._values;
    var index = binarySearch(times, time, JulianDate.compare);

    if (index < 0) {
      index = ~index;

      if (index === 0) {
        var startTime = times[index];
        timeout = this._backwardExtrapolationDuration;
        if (
          this._backwardExtrapolationType === ExtrapolationType$1.NONE ||
          (timeout !== 0 &&
            JulianDate.secondsDifference(startTime, time) > timeout)
        ) {
          return undefined;
        }
        if (this._backwardExtrapolationType === ExtrapolationType$1.HOLD) {
          return innerType.unpack(values, 0, result);
        }
      }

      if (index >= timesLength) {
        index = timesLength - 1;
        var endTime = times[index];
        timeout = this._forwardExtrapolationDuration;
        if (
          this._forwardExtrapolationType === ExtrapolationType$1.NONE ||
          (timeout !== 0 && JulianDate.secondsDifference(time, endTime) > timeout)
        ) {
          return undefined;
        }
        if (this._forwardExtrapolationType === ExtrapolationType$1.HOLD) {
          index = timesLength - 1;
          return innerType.unpack(values, index * innerType.packedLength, result);
        }
      }

      var xTable = this._xTable;
      var yTable = this._yTable;
      var interpolationAlgorithm = this._interpolationAlgorithm;
      var packedInterpolationLength = this._packedInterpolationLength;
      var inputOrder = this._inputOrder;

      if (this._updateTableLength) {
        this._updateTableLength = false;
        var numberOfPoints = Math.min(
          interpolationAlgorithm.getRequiredDataPoints(
            this._interpolationDegree,
            inputOrder
          ),
          timesLength
        );
        if (numberOfPoints !== this._numberOfPoints) {
          this._numberOfPoints = numberOfPoints;
          xTable.length = numberOfPoints;
          yTable.length = numberOfPoints * packedInterpolationLength;
        }
      }

      var degree = this._numberOfPoints - 1;
      if (degree < 1) {
        return undefined;
      }

      var firstIndex = 0;
      var lastIndex = timesLength - 1;
      var pointsInCollection = lastIndex - firstIndex + 1;

      if (pointsInCollection >= degree + 1) {
        var computedFirstIndex = index - ((degree / 2) | 0) - 1;
        if (computedFirstIndex < firstIndex) {
          computedFirstIndex = firstIndex;
        }
        var computedLastIndex = computedFirstIndex + degree;
        if (computedLastIndex > lastIndex) {
          computedLastIndex = lastIndex;
          computedFirstIndex = computedLastIndex - degree;
          if (computedFirstIndex < firstIndex) {
            computedFirstIndex = firstIndex;
          }
        }

        firstIndex = computedFirstIndex;
        lastIndex = computedLastIndex;
      }
      var length = lastIndex - firstIndex + 1;

      // Build the tables
      for (var i = 0; i < length; ++i) {
        xTable[i] = JulianDate.secondsDifference(
          times[firstIndex + i],
          times[lastIndex]
        );
      }

      if (!defined(innerType.convertPackedArrayForInterpolation)) {
        var destinationIndex = 0;
        var packedLength = this._packedLength;
        var sourceIndex = firstIndex * packedLength;
        var stop = (lastIndex + 1) * packedLength;

        while (sourceIndex < stop) {
          yTable[destinationIndex] = values[sourceIndex];
          sourceIndex++;
          destinationIndex++;
        }
      } else {
        innerType.convertPackedArrayForInterpolation(
          values,
          firstIndex,
          lastIndex,
          yTable
        );
      }

      // Interpolate!
      var x = JulianDate.secondsDifference(time, times[lastIndex]);
      var interpolationResult;
      if (inputOrder === 0 || !defined(interpolationAlgorithm.interpolate)) {
        interpolationResult = interpolationAlgorithm.interpolateOrderZero(
          x,
          xTable,
          yTable,
          packedInterpolationLength,
          this._interpolationResult
        );
      } else {
        var yStride = Math.floor(packedInterpolationLength / (inputOrder + 1));
        interpolationResult = interpolationAlgorithm.interpolate(
          x,
          xTable,
          yTable,
          yStride,
          inputOrder,
          inputOrder,
          this._interpolationResult
        );
      }

      if (!defined(innerType.unpackInterpolationResult)) {
        return innerType.unpack(interpolationResult, 0, result);
      }
      return innerType.unpackInterpolationResult(
        interpolationResult,
        values,
        firstIndex,
        lastIndex,
        result
      );
    }
    return innerType.unpack(values, index * this._packedLength, result);
  };

  /**
   * Sets the algorithm and degree to use when interpolating a value.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {InterpolationAlgorithm} [options.interpolationAlgorithm] The new interpolation algorithm.  If undefined, the existing property will be unchanged.
   * @param {Number} [options.interpolationDegree] The new interpolation degree.  If undefined, the existing property will be unchanged.
   */
  SampledProperty.prototype.setInterpolationOptions = function (options) {
    if (!defined(options)) {
      return;
    }

    var valuesChanged = false;

    var interpolationAlgorithm = options.interpolationAlgorithm;
    var interpolationDegree = options.interpolationDegree;

    if (
      defined(interpolationAlgorithm) &&
      this._interpolationAlgorithm !== interpolationAlgorithm
    ) {
      this._interpolationAlgorithm = interpolationAlgorithm;
      valuesChanged = true;
    }

    if (
      defined(interpolationDegree) &&
      this._interpolationDegree !== interpolationDegree
    ) {
      this._interpolationDegree = interpolationDegree;
      valuesChanged = true;
    }

    if (valuesChanged) {
      this._updateTableLength = true;
      this._definitionChanged.raiseEvent(this);
    }
  };

  /**
   * Adds a new sample.
   *
   * @param {JulianDate} time The sample time.
   * @param {Packable} value The value at the provided time.
   * @param {Packable[]} [derivatives] The array of derivatives at the provided time.
   */
  SampledProperty.prototype.addSample = function (time, value, derivatives) {
    var innerDerivativeTypes = this._innerDerivativeTypes;
    var hasDerivatives = defined(innerDerivativeTypes);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    Check.defined("value", value);
    if (hasDerivatives) {
      Check.defined("derivatives", derivatives);
    }
    //>>includeEnd('debug');

    var innerType = this._innerType;
    var data = [];
    data.push(time);
    innerType.pack(value, data, data.length);

    if (hasDerivatives) {
      var derivativesLength = innerDerivativeTypes.length;
      for (var x = 0; x < derivativesLength; x++) {
        innerDerivativeTypes[x].pack(derivatives[x], data, data.length);
      }
    }
    mergeNewSamples(
      undefined,
      this._times,
      this._values,
      data,
      this._packedLength
    );
    this._updateTableLength = true;
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Adds an array of samples.
   *
   * @param {JulianDate[]} times An array of JulianDate instances where each index is a sample time.
   * @param {Packable[]} values The array of values, where each value corresponds to the provided times index.
   * @param {Array[]} [derivativeValues] An array where each item is the array of derivatives at the equivalent time index.
   *
   * @exception {DeveloperError} times and values must be the same length.
   * @exception {DeveloperError} times and derivativeValues must be the same length.
   */
  SampledProperty.prototype.addSamples = function (
    times,
    values,
    derivativeValues
  ) {
    var innerDerivativeTypes = this._innerDerivativeTypes;
    var hasDerivatives = defined(innerDerivativeTypes);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("times", times);
    Check.defined("values", values);
    if (times.length !== values.length) {
      throw new DeveloperError("times and values must be the same length.");
    }
    if (
      hasDerivatives &&
      (!defined(derivativeValues) || derivativeValues.length !== times.length)
    ) {
      throw new DeveloperError(
        "times and derivativeValues must be the same length."
      );
    }
    //>>includeEnd('debug');

    var innerType = this._innerType;
    var length = times.length;
    var data = [];
    for (var i = 0; i < length; i++) {
      data.push(times[i]);
      innerType.pack(values[i], data, data.length);

      if (hasDerivatives) {
        var derivatives = derivativeValues[i];
        var derivativesLength = innerDerivativeTypes.length;
        for (var x = 0; x < derivativesLength; x++) {
          innerDerivativeTypes[x].pack(derivatives[x], data, data.length);
        }
      }
    }
    mergeNewSamples(
      undefined,
      this._times,
      this._values,
      data,
      this._packedLength
    );
    this._updateTableLength = true;
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Adds samples as a single packed array where each new sample is represented as a date,
   * followed by the packed representation of the corresponding value and derivatives.
   *
   * @param {Number[]} packedSamples The array of packed samples.
   * @param {JulianDate} [epoch] If any of the dates in packedSamples are numbers, they are considered an offset from this epoch, in seconds.
   */
  SampledProperty.prototype.addSamplesPackedArray = function (
    packedSamples,
    epoch
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("packedSamples", packedSamples);
    //>>includeEnd('debug');

    mergeNewSamples(
      epoch,
      this._times,
      this._values,
      packedSamples,
      this._packedLength
    );
    this._updateTableLength = true;
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * Removes a sample at the given time, if present.
   *
   * @param {JulianDate} time The sample time.
   * @returns {Boolean} <code>true</code> if a sample at time was removed, <code>false</code> otherwise.
   */
  SampledProperty.prototype.removeSample = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var index = binarySearch(this._times, time, JulianDate.compare);
    if (index < 0) {
      return false;
    }
    removeSamples(this, index, 1);
    return true;
  };

  function removeSamples(property, startIndex, numberToRemove) {
    var packedLength = property._packedLength;
    property._times.splice(startIndex, numberToRemove);
    property._values.splice(
      startIndex * packedLength,
      numberToRemove * packedLength
    );
    property._updateTableLength = true;
    property._definitionChanged.raiseEvent(property);
  }

  /**
   * Removes all samples for the given time interval.
   *
   * @param {TimeInterval} time The time interval for which to remove all samples.
   */
  SampledProperty.prototype.removeSamples = function (timeInterval) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("timeInterval", timeInterval);
    //>>includeEnd('debug');

    var times = this._times;
    var startIndex = binarySearch(times, timeInterval.start, JulianDate.compare);
    if (startIndex < 0) {
      startIndex = ~startIndex;
    } else if (!timeInterval.isStartIncluded) {
      ++startIndex;
    }
    var stopIndex = binarySearch(times, timeInterval.stop, JulianDate.compare);
    if (stopIndex < 0) {
      stopIndex = ~stopIndex;
    } else if (timeInterval.isStopIncluded) {
      ++stopIndex;
    }

    removeSamples(this, startIndex, stopIndex - startIndex);
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  SampledProperty.prototype.equals = function (other) {
    if (this === other) {
      return true;
    }
    if (!defined(other)) {
      return false;
    }

    if (
      this._type !== other._type || //
      this._interpolationDegree !== other._interpolationDegree || //
      this._interpolationAlgorithm !== other._interpolationAlgorithm
    ) {
      return false;
    }

    var derivativeTypes = this._derivativeTypes;
    var hasDerivatives = defined(derivativeTypes);
    var otherDerivativeTypes = other._derivativeTypes;
    var otherHasDerivatives = defined(otherDerivativeTypes);
    if (hasDerivatives !== otherHasDerivatives) {
      return false;
    }

    var i;
    var length;
    if (hasDerivatives) {
      length = derivativeTypes.length;
      if (length !== otherDerivativeTypes.length) {
        return false;
      }

      for (i = 0; i < length; i++) {
        if (derivativeTypes[i] !== otherDerivativeTypes[i]) {
          return false;
        }
      }
    }

    var times = this._times;
    var otherTimes = other._times;
    length = times.length;

    if (length !== otherTimes.length) {
      return false;
    }

    for (i = 0; i < length; i++) {
      if (!JulianDate.equals(times[i], otherTimes[i])) {
        return false;
      }
    }

    var values = this._values;
    var otherValues = other._values;
    length = values.length;

    //Since time lengths are equal, values length and other length are guaranteed to be equal.
    for (i = 0; i < length; i++) {
      if (values[i] !== otherValues[i]) {
        return false;
      }
    }

    return true;
  };

  //Exposed for testing.
  SampledProperty._mergeNewSamples = mergeNewSamples;

  /**
   * A {@link SampledProperty} which is also a {@link PositionProperty}.
   *
   * @alias SampledPositionProperty
   * @constructor
   *
   * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
   * @param {Number} [numberOfDerivatives=0] The number of derivatives that accompany each position; i.e. velocity, acceleration, etc...
   */
  function SampledPositionProperty(referenceFrame, numberOfDerivatives) {
    numberOfDerivatives = defaultValue(numberOfDerivatives, 0);

    var derivativeTypes;
    if (numberOfDerivatives > 0) {
      derivativeTypes = new Array(numberOfDerivatives);
      for (var i = 0; i < numberOfDerivatives; i++) {
        derivativeTypes[i] = Cartesian3;
      }
    }

    this._numberOfDerivatives = numberOfDerivatives;
    this._property = new SampledProperty(Cartesian3, derivativeTypes);
    this._definitionChanged = new Event();
    this._referenceFrame = defaultValue(referenceFrame, ReferenceFrame$1.FIXED);

    this._property._definitionChanged.addEventListener(function () {
      this._definitionChanged.raiseEvent(this);
    }, this);
  }

  Object.defineProperties(SampledPositionProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof SampledPositionProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._property.isConstant;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof SampledPositionProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the reference frame in which the position is defined.
     * @memberof SampledPositionProperty.prototype
     * @type {ReferenceFrame}
     * @default ReferenceFrame.FIXED;
     */
    referenceFrame: {
      get: function () {
        return this._referenceFrame;
      },
    },
    /**
     * Gets the degree of interpolation to perform when retrieving a value. Call <code>setInterpolationOptions</code> to set this.
     * @memberof SampledPositionProperty.prototype
     *
     * @type {Number}
     * @default 1
     * @readonly
     */
    interpolationDegree: {
      get: function () {
        return this._property.interpolationDegree;
      },
    },
    /**
     * Gets the interpolation algorithm to use when retrieving a value. Call <code>setInterpolationOptions</code> to set this.
     * @memberof SampledPositionProperty.prototype
     *
     * @type {InterpolationAlgorithm}
     * @default LinearApproximation
     * @readonly
     */
    interpolationAlgorithm: {
      get: function () {
        return this._property.interpolationAlgorithm;
      },
    },
    /**
     * The number of derivatives contained by this property; i.e. 0 for just position, 1 for velocity, etc.
     * @memberof SampledPositionProperty.prototype
     *
     * @type {Number}
     * @default 0
     */
    numberOfDerivatives: {
      get: function () {
        return this._numberOfDerivatives;
      },
    },
    /**
     * Gets or sets the type of extrapolation to perform when a value
     * is requested at a time after any available samples.
     * @memberof SampledPositionProperty.prototype
     * @type {ExtrapolationType}
     * @default ExtrapolationType.NONE
     */
    forwardExtrapolationType: {
      get: function () {
        return this._property.forwardExtrapolationType;
      },
      set: function (value) {
        this._property.forwardExtrapolationType = value;
      },
    },
    /**
     * Gets or sets the amount of time to extrapolate forward before
     * the property becomes undefined.  A value of 0 will extrapolate forever.
     * @memberof SampledPositionProperty.prototype
     * @type {Number}
     * @default 0
     */
    forwardExtrapolationDuration: {
      get: function () {
        return this._property.forwardExtrapolationDuration;
      },
      set: function (value) {
        this._property.forwardExtrapolationDuration = value;
      },
    },
    /**
     * Gets or sets the type of extrapolation to perform when a value
     * is requested at a time before any available samples.
     * @memberof SampledPositionProperty.prototype
     * @type {ExtrapolationType}
     * @default ExtrapolationType.NONE
     */
    backwardExtrapolationType: {
      get: function () {
        return this._property.backwardExtrapolationType;
      },
      set: function (value) {
        this._property.backwardExtrapolationType = value;
      },
    },
    /**
     * Gets or sets the amount of time to extrapolate backward
     * before the property becomes undefined.  A value of 0 will extrapolate forever.
     * @memberof SampledPositionProperty.prototype
     * @type {Number}
     * @default 0
     */
    backwardExtrapolationDuration: {
      get: function () {
        return this._property.backwardExtrapolationDuration;
      },
      set: function (value) {
        this._property.backwardExtrapolationDuration = value;
      },
    },
  });

  /**
   * Gets the position at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  SampledPositionProperty.prototype.getValue = function (time, result) {
    return this.getValueInReferenceFrame(time, ReferenceFrame$1.FIXED, result);
  };

  /**
   * Gets the position at the provided time and in the provided reference frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  SampledPositionProperty.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    Check.defined("referenceFrame", referenceFrame);
    //>>includeEnd('debug');

    result = this._property.getValue(time, result);
    if (defined(result)) {
      return PositionProperty.convertToReferenceFrame(
        time,
        result,
        this._referenceFrame,
        referenceFrame,
        result
      );
    }
    return undefined;
  };

  /**
   * Sets the algorithm and degree to use when interpolating a position.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {InterpolationAlgorithm} [options.interpolationAlgorithm] The new interpolation algorithm.  If undefined, the existing property will be unchanged.
   * @param {Number} [options.interpolationDegree] The new interpolation degree.  If undefined, the existing property will be unchanged.
   */
  SampledPositionProperty.prototype.setInterpolationOptions = function (options) {
    this._property.setInterpolationOptions(options);
  };

  /**
   * Adds a new sample.
   *
   * @param {JulianDate} time The sample time.
   * @param {Cartesian3} position The position at the provided time.
   * @param {Cartesian3[]} [derivatives] The array of derivative values at the provided time.
   */
  SampledPositionProperty.prototype.addSample = function (
    time,
    position,
    derivatives
  ) {
    var numberOfDerivatives = this._numberOfDerivatives;
    //>>includeStart('debug', pragmas.debug);
    if (
      numberOfDerivatives > 0 &&
      (!defined(derivatives) || derivatives.length !== numberOfDerivatives)
    ) {
      throw new DeveloperError(
        "derivatives length must be equal to the number of derivatives."
      );
    }
    //>>includeEnd('debug');
    this._property.addSample(time, position, derivatives);
  };

  /**
   * Adds multiple samples via parallel arrays.
   *
   * @param {JulianDate[]} times An array of JulianDate instances where each index is a sample time.
   * @param {Cartesian3[]} positions An array of Cartesian3 position instances, where each value corresponds to the provided time index.
   * @param {Array[]} [derivatives] An array where each value is another array containing derivatives for the corresponding time index.
   *
   * @exception {DeveloperError} All arrays must be the same length.
   */
  SampledPositionProperty.prototype.addSamples = function (
    times,
    positions,
    derivatives
  ) {
    this._property.addSamples(times, positions, derivatives);
  };

  /**
   * Adds samples as a single packed array where each new sample is represented as a date,
   * followed by the packed representation of the corresponding value and derivatives.
   *
   * @param {Number[]} packedSamples The array of packed samples.
   * @param {JulianDate} [epoch] If any of the dates in packedSamples are numbers, they are considered an offset from this epoch, in seconds.
   */
  SampledPositionProperty.prototype.addSamplesPackedArray = function (
    packedSamples,
    epoch
  ) {
    this._property.addSamplesPackedArray(packedSamples, epoch);
  };

  /**
   * Removes a sample at the given time, if present.
   *
   * @param {JulianDate} time The sample time.
   * @returns {Boolean} <code>true</code> if a sample at time was removed, <code>false</code> otherwise.
   */
  SampledPositionProperty.prototype.removeSample = function (time) {
    return this._property.removeSample(time);
  };

  /**
   * Removes all samples for the given time interval.
   *
   * @param {TimeInterval} time The time interval for which to remove all samples.
   */
  SampledPositionProperty.prototype.removeSamples = function (timeInterval) {
    this._property.removeSamples(timeInterval);
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  SampledPositionProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof SampledPositionProperty &&
      Property.equals(this._property, other._property) && //
        this._referenceFrame === other._referenceFrame)
    );
  };

  /**
   * Defined the orientation of stripes in {@link StripeMaterialProperty}.
   *
   * @enum {Number}
   */
  var StripeOrientation = {
    /**
     * Horizontal orientation.
     * @type {Number}
     */
    HORIZONTAL: 0,

    /**
     * Vertical orientation.
     * @type {Number}
     */
    VERTICAL: 1,
  };
  var StripeOrientation$1 = Object.freeze(StripeOrientation);

  var defaultOrientation = StripeOrientation$1.HORIZONTAL;
  var defaultEvenColor$1 = Color.WHITE;
  var defaultOddColor$1 = Color.BLACK;
  var defaultOffset$3 = 0;
  var defaultRepeat$2 = 1;

  /**
   * A {@link MaterialProperty} that maps to stripe {@link Material} uniforms.
   * @alias StripeMaterialProperty
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Property|StripeOrientation} [options.orientation=StripeOrientation.HORIZONTAL] A Property specifying the {@link StripeOrientation}.
   * @param {Property|Color} [options.evenColor=Color.WHITE] A Property specifying the first {@link Color}.
   * @param {Property|Color} [options.oddColor=Color.BLACK] A Property specifying the second {@link Color}.
   * @param {Property|Number} [options.offset=0] A numeric Property specifying how far into the pattern to start the material.
   * @param {Property|Number} [options.repeat=1] A numeric Property specifying how many times the stripes repeat.
   */
  function StripeMaterialProperty(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._definitionChanged = new Event();
    this._orientation = undefined;
    this._orientationSubscription = undefined;
    this._evenColor = undefined;
    this._evenColorSubscription = undefined;
    this._oddColor = undefined;
    this._oddColorSubscription = undefined;
    this._offset = undefined;
    this._offsetSubscription = undefined;
    this._repeat = undefined;
    this._repeatSubscription = undefined;

    this.orientation = options.orientation;
    this.evenColor = options.evenColor;
    this.oddColor = options.oddColor;
    this.offset = options.offset;
    this.repeat = options.repeat;
  }

  Object.defineProperties(StripeMaterialProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof StripeMaterialProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return (
          Property.isConstant(this._orientation) && //
          Property.isConstant(this._evenColor) && //
          Property.isConstant(this._oddColor) && //
          Property.isConstant(this._offset) && //
          Property.isConstant(this._repeat)
        );
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof StripeMaterialProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },

    /**
     * Gets or sets the Property specifying the {@link StripeOrientation}/
     * @memberof StripeMaterialProperty.prototype
     * @type {Property|undefined}
     * @default StripeOrientation.HORIZONTAL
     */
    orientation: createPropertyDescriptor("orientation"),

    /**
     * Gets or sets the Property specifying the first {@link Color}.
     * @memberof StripeMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.WHITE
     */
    evenColor: createPropertyDescriptor("evenColor"),

    /**
     * Gets or sets the Property specifying the second {@link Color}.
     * @memberof StripeMaterialProperty.prototype
     * @type {Property|undefined}
     * @default Color.BLACK
     */
    oddColor: createPropertyDescriptor("oddColor"),

    /**
     * Gets or sets the numeric Property specifying the point into the pattern
     * to begin drawing; with 0.0 being the beginning of the even color, 1.0 the beginning
     * of the odd color, 2.0 being the even color again, and any multiple or fractional values
     * being in between.
     * @memberof StripeMaterialProperty.prototype
     * @type {Property|undefined}
     * @default 0.0
     */
    offset: createPropertyDescriptor("offset"),

    /**
     * Gets or sets the numeric Property specifying how many times the stripes repeat.
     * @memberof StripeMaterialProperty.prototype
     * @type {Property|undefined}
     * @default 1.0
     */
    repeat: createPropertyDescriptor("repeat"),
  });

  /**
   * Gets the {@link Material} type at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the type.
   * @returns {String} The type of material.
   */
  StripeMaterialProperty.prototype.getType = function (time) {
    return "Stripe";
  };

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  StripeMaterialProperty.prototype.getValue = function (time, result) {
    if (!defined(result)) {
      result = {};
    }
    result.horizontal =
      Property.getValueOrDefault(this._orientation, time, defaultOrientation) ===
      StripeOrientation$1.HORIZONTAL;
    result.evenColor = Property.getValueOrClonedDefault(
      this._evenColor,
      time,
      defaultEvenColor$1,
      result.evenColor
    );
    result.oddColor = Property.getValueOrClonedDefault(
      this._oddColor,
      time,
      defaultOddColor$1,
      result.oddColor
    );
    result.offset = Property.getValueOrDefault(this._offset, time, defaultOffset$3);
    result.repeat = Property.getValueOrDefault(this._repeat, time, defaultRepeat$2);
    return result;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  StripeMaterialProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof StripeMaterialProperty && //
      Property.equals(this._orientation, other._orientation) && //
      Property.equals(this._evenColor, other._evenColor) && //
      Property.equals(this._oddColor, other._oddColor) && //
      Property.equals(this._offset, other._offset) && //
        Property.equals(this._repeat, other._repeat))
    );
  };

  /**
   * A {@link TimeIntervalCollectionProperty} which is also a {@link PositionProperty}.
   *
   * @alias TimeIntervalCollectionPositionProperty
   * @constructor
   *
   * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
   */
  function TimeIntervalCollectionPositionProperty(referenceFrame) {
    this._definitionChanged = new Event();
    this._intervals = new TimeIntervalCollection();
    this._intervals.changedEvent.addEventListener(
      TimeIntervalCollectionPositionProperty.prototype._intervalsChanged,
      this
    );
    this._referenceFrame = defaultValue(referenceFrame, ReferenceFrame$1.FIXED);
  }

  Object.defineProperties(TimeIntervalCollectionPositionProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof TimeIntervalCollectionPositionProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._intervals.isEmpty;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is considered to have changed if a call to getValue would return
     * a different result for the same time.
     * @memberof TimeIntervalCollectionPositionProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the interval collection.
     * @memberof TimeIntervalCollectionPositionProperty.prototype
     * @type {TimeIntervalCollection}
     */
    intervals: {
      get: function () {
        return this._intervals;
      },
    },
    /**
     * Gets the reference frame in which the position is defined.
     * @memberof TimeIntervalCollectionPositionProperty.prototype
     * @type {ReferenceFrame}
     * @default ReferenceFrame.FIXED;
     */
    referenceFrame: {
      get: function () {
        return this._referenceFrame;
      },
    },
  });

  /**
   * Gets the value of the property at the provided time in the fixed frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  TimeIntervalCollectionPositionProperty.prototype.getValue = function (
    time,
    result
  ) {
    return this.getValueInReferenceFrame(time, ReferenceFrame$1.FIXED, result);
  };

  /**
   * Gets the value of the property at the provided time and in the provided reference frame.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  TimeIntervalCollectionPositionProperty.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    if (!defined(referenceFrame)) {
      throw new DeveloperError("referenceFrame is required.");
    }
    //>>includeEnd('debug');

    var position = this._intervals.findDataForIntervalContainingDate(time);
    if (defined(position)) {
      return PositionProperty.convertToReferenceFrame(
        time,
        position,
        this._referenceFrame,
        referenceFrame,
        result
      );
    }
    return undefined;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  TimeIntervalCollectionPositionProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof TimeIntervalCollectionPositionProperty && //
      this._intervals.equals(other._intervals, Property.equals) && //
        this._referenceFrame === other._referenceFrame)
    );
  };

  /**
   * @private
   */
  TimeIntervalCollectionPositionProperty.prototype._intervalsChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * A {@link Property} which is defined by a {@link TimeIntervalCollection}, where the
   * data property of each {@link TimeInterval} represents the value at time.
   *
   * @alias TimeIntervalCollectionProperty
   * @constructor
   *
   * @example
   * //Create a Cartesian2 interval property which contains data on August 1st, 2012
   * //and uses a different value every 6 hours.
   * var composite = new Cesium.TimeIntervalCollectionProperty();
   * composite.intervals.addInterval(Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2012-08-01T00:00:00.00Z/2012-08-01T06:00:00.00Z',
   *     isStartIncluded : true,
   *     isStopIncluded : false,
   *     data : new Cesium.Cartesian2(2.0, 3.4)
   * }));
   * composite.intervals.addInterval(Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2012-08-01T06:00:00.00Z/2012-08-01T12:00:00.00Z',
   *     isStartIncluded : true,
   *     isStopIncluded : false,
   *     data : new Cesium.Cartesian2(12.0, 2.7)
   * }));
   * composite.intervals.addInterval(Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2012-08-01T12:00:00.00Z/2012-08-01T18:00:00.00Z',
   *     isStartIncluded : true,
   *     isStopIncluded : false,
   *     data : new Cesium.Cartesian2(5.0, 12.4)
   * }));
   * composite.intervals.addInterval(Cesium.TimeInterval.fromIso8601({
   *     iso8601 : '2012-08-01T18:00:00.00Z/2012-08-02T00:00:00.00Z',
   *     isStartIncluded : true,
   *     isStopIncluded : true,
   *     data : new Cesium.Cartesian2(85.0, 4.1)
   * }));
   */
  function TimeIntervalCollectionProperty() {
    this._definitionChanged = new Event();
    this._intervals = new TimeIntervalCollection();
    this._intervals.changedEvent.addEventListener(
      TimeIntervalCollectionProperty.prototype._intervalsChanged,
      this
    );
  }

  Object.defineProperties(TimeIntervalCollectionProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.  A property is considered
     * constant if getValue always returns the same result for the current definition.
     * @memberof TimeIntervalCollectionProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return this._intervals.isEmpty;
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * The definition is changed whenever setValue is called with data different
     * than the current value.
     * @memberof TimeIntervalCollectionProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets the interval collection.
     * @memberof TimeIntervalCollectionProperty.prototype
     *
     * @type {TimeIntervalCollection}
     */
    intervals: {
      get: function () {
        return this._intervals;
      },
    },
  });

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve the value.
   * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  TimeIntervalCollectionProperty.prototype.getValue = function (time, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required");
    }
    //>>includeEnd('debug');

    var value = this._intervals.findDataForIntervalContainingDate(time);
    if (defined(value) && typeof value.clone === "function") {
      return value.clone(result);
    }
    return value;
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  TimeIntervalCollectionProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof TimeIntervalCollectionProperty && //
        this._intervals.equals(other._intervals, Property.equals))
    );
  };

  /**
   * @private
   */
  TimeIntervalCollectionProperty.prototype._intervalsChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  /**
   * A {@link Property} which evaluates to a {@link Cartesian3} vector
   * based on the velocity of the provided {@link PositionProperty}.
   *
   * @alias VelocityVectorProperty
   * @constructor
   *
   * @param {PositionProperty} [position] The position property used to compute the velocity.
   * @param {Boolean} [normalize=true] Whether to normalize the computed velocity vector.
   *
   * @example
   * //Create an entity with a billboard rotated to match its velocity.
   * var position = new Cesium.SampledProperty();
   * position.addSamples(...);
   * var entity = viewer.entities.add({
   *   position : position,
   *   billboard : {
   *     image : 'image.png',
   *     alignedAxis : new Cesium.VelocityVectorProperty(position, true) // alignedAxis must be a unit vector
   *   }
   * }));
   */
  function VelocityVectorProperty(position, normalize) {
    this._position = undefined;
    this._subscription = undefined;
    this._definitionChanged = new Event();
    this._normalize = defaultValue(normalize, true);

    this.position = position;
  }

  Object.defineProperties(VelocityVectorProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.
     * @memberof VelocityVectorProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return Property.isConstant(this._position);
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * @memberof VelocityVectorProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the position property used to compute the velocity vector.
     * @memberof VelocityVectorProperty.prototype
     *
     * @type {Property|undefined}
     */
    position: {
      get: function () {
        return this._position;
      },
      set: function (value) {
        var oldValue = this._position;
        if (oldValue !== value) {
          if (defined(oldValue)) {
            this._subscription();
          }

          this._position = value;

          if (defined(value)) {
            this._subscription = value._definitionChanged.addEventListener(
              function () {
                this._definitionChanged.raiseEvent(this);
              },
              this
            );
          }

          this._definitionChanged.raiseEvent(this);
        }
      },
    },
    /**
     * Gets or sets whether the vector produced by this property
     * will be normalized or not.
     * @memberof VelocityVectorProperty.prototype
     *
     * @type {Boolean}
     */
    normalize: {
      get: function () {
        return this._normalize;
      },
      set: function (value) {
        if (this._normalize === value) {
          return;
        }

        this._normalize = value;
        this._definitionChanged.raiseEvent(this);
      },
    },
  });

  var position1Scratch = new Cartesian3();
  var position2Scratch = new Cartesian3();
  var timeScratch = new JulianDate();
  var step = 1.0 / 60.0;

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} [time] The time for which to retrieve the value.
   * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  VelocityVectorProperty.prototype.getValue = function (time, result) {
    return this._getValue(time, result);
  };

  /**
   * @private
   */
  VelocityVectorProperty.prototype._getValue = function (
    time,
    velocityResult,
    positionResult
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required");
    }
    //>>includeEnd('debug');

    if (!defined(velocityResult)) {
      velocityResult = new Cartesian3();
    }

    var property = this._position;
    if (Property.isConstant(property)) {
      return this._normalize
        ? undefined
        : Cartesian3.clone(Cartesian3.ZERO, velocityResult);
    }

    var position1 = property.getValue(time, position1Scratch);
    var position2 = property.getValue(
      JulianDate.addSeconds(time, step, timeScratch),
      position2Scratch
    );

    //If we don't have a position for now, return undefined.
    if (!defined(position1)) {
      return undefined;
    }

    //If we don't have a position for now + step, see if we have a position for now - step.
    if (!defined(position2)) {
      position2 = position1;
      position1 = property.getValue(
        JulianDate.addSeconds(time, -step, timeScratch),
        position2Scratch
      );

      if (!defined(position1)) {
        return undefined;
      }
    }

    if (Cartesian3.equals(position1, position2)) {
      return this._normalize
        ? undefined
        : Cartesian3.clone(Cartesian3.ZERO, velocityResult);
    }

    if (defined(positionResult)) {
      position1.clone(positionResult);
    }

    var velocity = Cartesian3.subtract(position2, position1, velocityResult);
    if (this._normalize) {
      return Cartesian3.normalize(velocity, velocityResult);
    }

    return Cartesian3.divideByScalar(velocity, step, velocityResult);
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  VelocityVectorProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof VelocityVectorProperty &&
        Property.equals(this._position, other._position))
    );
  };

  /**
   * A {@link Property} which evaluates to a {@link Quaternion} rotation
   * based on the velocity of the provided {@link PositionProperty}.
   *
   * @alias VelocityOrientationProperty
   * @constructor
   *
   * @param {PositionProperty} [position] The position property used to compute the orientation.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid used to determine which way is up.
   *
   * @example
   * //Create an entity with position and orientation.
   * var position = new Cesium.SampledProperty();
   * position.addSamples(...);
   * var entity = viewer.entities.add({
   *   position : position,
   *   orientation : new Cesium.VelocityOrientationProperty(position)
   * }));
   */
  function VelocityOrientationProperty(position, ellipsoid) {
    this._velocityVectorProperty = new VelocityVectorProperty(position, true);
    this._subscription = undefined;
    this._ellipsoid = undefined;
    this._definitionChanged = new Event();

    this.ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    var that = this;
    this._velocityVectorProperty.definitionChanged.addEventListener(function () {
      that._definitionChanged.raiseEvent(that);
    });
  }

  Object.defineProperties(VelocityOrientationProperty.prototype, {
    /**
     * Gets a value indicating if this property is constant.
     * @memberof VelocityOrientationProperty.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isConstant: {
      get: function () {
        return Property.isConstant(this._velocityVectorProperty);
      },
    },
    /**
     * Gets the event that is raised whenever the definition of this property changes.
     * @memberof VelocityOrientationProperty.prototype
     *
     * @type {Event}
     * @readonly
     */
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    /**
     * Gets or sets the position property used to compute orientation.
     * @memberof VelocityOrientationProperty.prototype
     *
     * @type {Property|undefined}
     */
    position: {
      get: function () {
        return this._velocityVectorProperty.position;
      },
      set: function (value) {
        this._velocityVectorProperty.position = value;
      },
    },
    /**
     * Gets or sets the ellipsoid used to determine which way is up.
     * @memberof VelocityOrientationProperty.prototype
     *
     * @type {Property|undefined}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
      set: function (value) {
        var oldValue = this._ellipsoid;
        if (oldValue !== value) {
          this._ellipsoid = value;
          this._definitionChanged.raiseEvent(this);
        }
      },
    },
  });

  var positionScratch$8 = new Cartesian3();
  var velocityScratch = new Cartesian3();
  var rotationScratch = new Matrix3();

  /**
   * Gets the value of the property at the provided time.
   *
   * @param {JulianDate} [time] The time for which to retrieve the value.
   * @param {Quaternion} [result] The object to store the value into, if omitted, a new instance is created and returned.
   * @returns {Quaternion} The modified result parameter or a new instance if the result parameter was not supplied.
   */
  VelocityOrientationProperty.prototype.getValue = function (time, result) {
    var velocity = this._velocityVectorProperty._getValue(
      time,
      velocityScratch,
      positionScratch$8
    );

    if (!defined(velocity)) {
      return undefined;
    }

    Transforms.rotationMatrixFromPositionVelocity(
      positionScratch$8,
      velocity,
      this._ellipsoid,
      rotationScratch
    );
    return Quaternion.fromRotationMatrix(rotationScratch, result);
  };

  /**
   * Compares this property to the provided property and returns
   * <code>true</code> if they are equal, <code>false</code> otherwise.
   *
   * @param {Property} [other] The other property.
   * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
   */
  VelocityOrientationProperty.prototype.equals = function (other) {
    return (
      this === other || //
      (other instanceof VelocityOrientationProperty &&
        Property.equals(
          this._velocityVectorProperty,
          other._velocityVectorProperty
        ) &&
        (this._ellipsoid === other._ellipsoid ||
          this._ellipsoid.equals(other._ellipsoid)))
    );
  };

  // A marker type to distinguish CZML properties where we need to end up with a unit vector.
  // The data is still loaded into Cartesian3 objects but they are normalized.
  function UnitCartesian3() {}
  UnitCartesian3.packedLength = Cartesian3.packedLength;
  UnitCartesian3.unpack = Cartesian3.unpack;
  UnitCartesian3.pack = Cartesian3.pack;

  // As a side note, for the purposes of CZML, Quaternion always indicates a unit quaternion.

  var currentId;

  function createReferenceProperty(entityCollection, referenceString) {
    if (referenceString[0] === "#") {
      referenceString = currentId + referenceString;
    }
    return ReferenceProperty.fromString(entityCollection, referenceString);
  }

  function createSpecializedProperty(type, entityCollection, packetData) {
    if (defined(packetData.reference)) {
      return createReferenceProperty(entityCollection, packetData.reference);
    }

    if (defined(packetData.velocityReference)) {
      var referenceProperty = createReferenceProperty(
        entityCollection,
        packetData.velocityReference
      );
      switch (type) {
        case Cartesian3:
        case UnitCartesian3:
          return new VelocityVectorProperty(
            referenceProperty,
            type === UnitCartesian3
          );
        case Quaternion:
          return new VelocityOrientationProperty(referenceProperty);
      }
    }

    throw new RuntimeError(JSON.stringify(packetData) + " is not valid CZML.");
  }

  function createAdapterProperty(property, adapterFunction) {
    return new CallbackProperty(function (time, result) {
      return adapterFunction(property.getValue(time, result));
    }, property.isConstant);
  }

  var scratchCartesian$6 = new Cartesian3();
  var scratchSpherical = new Spherical();
  var scratchCartographic$8 = new Cartographic();
  var scratchTimeInterval = new TimeInterval();
  var scratchQuaternion = new Quaternion();

  function unwrapColorInterval(czmlInterval) {
    var rgbaf = czmlInterval.rgbaf;
    if (defined(rgbaf)) {
      return rgbaf;
    }

    var rgba = czmlInterval.rgba;
    if (!defined(rgba)) {
      return undefined;
    }

    var length = rgba.length;
    if (length === Color.packedLength) {
      return [
        Color.byteToFloat(rgba[0]),
        Color.byteToFloat(rgba[1]),
        Color.byteToFloat(rgba[2]),
        Color.byteToFloat(rgba[3]),
      ];
    }

    rgbaf = new Array(length);
    for (var i = 0; i < length; i += 5) {
      rgbaf[i] = rgba[i];
      rgbaf[i + 1] = Color.byteToFloat(rgba[i + 1]);
      rgbaf[i + 2] = Color.byteToFloat(rgba[i + 2]);
      rgbaf[i + 3] = Color.byteToFloat(rgba[i + 3]);
      rgbaf[i + 4] = Color.byteToFloat(rgba[i + 4]);
    }
    return rgbaf;
  }

  function unwrapUriInterval(czmlInterval, sourceUri) {
    var uri = defaultValue(czmlInterval.uri, czmlInterval);
    if (defined(sourceUri)) {
      return sourceUri.getDerivedResource({
        url: uri,
      });
    }

    return Resource.createIfNeeded(uri);
  }

  function unwrapRectangleInterval(czmlInterval) {
    var wsen = czmlInterval.wsen;
    if (defined(wsen)) {
      return wsen;
    }

    var wsenDegrees = czmlInterval.wsenDegrees;
    if (!defined(wsenDegrees)) {
      return undefined;
    }

    var length = wsenDegrees.length;
    if (length === Rectangle.packedLength) {
      return [
        CesiumMath.toRadians(wsenDegrees[0]),
        CesiumMath.toRadians(wsenDegrees[1]),
        CesiumMath.toRadians(wsenDegrees[2]),
        CesiumMath.toRadians(wsenDegrees[3]),
      ];
    }

    wsen = new Array(length);
    for (var i = 0; i < length; i += 5) {
      wsen[i] = wsenDegrees[i];
      wsen[i + 1] = CesiumMath.toRadians(wsenDegrees[i + 1]);
      wsen[i + 2] = CesiumMath.toRadians(wsenDegrees[i + 2]);
      wsen[i + 3] = CesiumMath.toRadians(wsenDegrees[i + 3]);
      wsen[i + 4] = CesiumMath.toRadians(wsenDegrees[i + 4]);
    }
    return wsen;
  }

  function convertUnitSphericalToCartesian(unitSpherical) {
    var length = unitSpherical.length;
    scratchSpherical.magnitude = 1.0;
    if (length === 2) {
      scratchSpherical.clock = unitSpherical[0];
      scratchSpherical.cone = unitSpherical[1];
      Cartesian3.fromSpherical(scratchSpherical, scratchCartesian$6);
      return [scratchCartesian$6.x, scratchCartesian$6.y, scratchCartesian$6.z];
    }

    var result = new Array((length / 3) * 4);
    for (var i = 0, j = 0; i < length; i += 3, j += 4) {
      result[j] = unitSpherical[i];

      scratchSpherical.clock = unitSpherical[i + 1];
      scratchSpherical.cone = unitSpherical[i + 2];
      Cartesian3.fromSpherical(scratchSpherical, scratchCartesian$6);

      result[j + 1] = scratchCartesian$6.x;
      result[j + 2] = scratchCartesian$6.y;
      result[j + 3] = scratchCartesian$6.z;
    }
    return result;
  }

  function convertSphericalToCartesian(spherical) {
    var length = spherical.length;
    if (length === 3) {
      scratchSpherical.clock = spherical[0];
      scratchSpherical.cone = spherical[1];
      scratchSpherical.magnitude = spherical[2];
      Cartesian3.fromSpherical(scratchSpherical, scratchCartesian$6);
      return [scratchCartesian$6.x, scratchCartesian$6.y, scratchCartesian$6.z];
    }

    var result = new Array(length);
    for (var i = 0; i < length; i += 4) {
      result[i] = spherical[i];

      scratchSpherical.clock = spherical[i + 1];
      scratchSpherical.cone = spherical[i + 2];
      scratchSpherical.magnitude = spherical[i + 3];
      Cartesian3.fromSpherical(scratchSpherical, scratchCartesian$6);

      result[i + 1] = scratchCartesian$6.x;
      result[i + 2] = scratchCartesian$6.y;
      result[i + 3] = scratchCartesian$6.z;
    }
    return result;
  }

  function convertCartographicRadiansToCartesian(cartographicRadians) {
    var length = cartographicRadians.length;
    if (length === 3) {
      scratchCartographic$8.longitude = cartographicRadians[0];
      scratchCartographic$8.latitude = cartographicRadians[1];
      scratchCartographic$8.height = cartographicRadians[2];
      Ellipsoid.WGS84.cartographicToCartesian(
        scratchCartographic$8,
        scratchCartesian$6
      );
      return [scratchCartesian$6.x, scratchCartesian$6.y, scratchCartesian$6.z];
    }

    var result = new Array(length);
    for (var i = 0; i < length; i += 4) {
      result[i] = cartographicRadians[i];

      scratchCartographic$8.longitude = cartographicRadians[i + 1];
      scratchCartographic$8.latitude = cartographicRadians[i + 2];
      scratchCartographic$8.height = cartographicRadians[i + 3];
      Ellipsoid.WGS84.cartographicToCartesian(
        scratchCartographic$8,
        scratchCartesian$6
      );

      result[i + 1] = scratchCartesian$6.x;
      result[i + 2] = scratchCartesian$6.y;
      result[i + 3] = scratchCartesian$6.z;
    }
    return result;
  }

  function convertCartographicDegreesToCartesian(cartographicDegrees) {
    var length = cartographicDegrees.length;
    if (length === 3) {
      scratchCartographic$8.longitude = CesiumMath.toRadians(
        cartographicDegrees[0]
      );
      scratchCartographic$8.latitude = CesiumMath.toRadians(cartographicDegrees[1]);
      scratchCartographic$8.height = cartographicDegrees[2];
      Ellipsoid.WGS84.cartographicToCartesian(
        scratchCartographic$8,
        scratchCartesian$6
      );
      return [scratchCartesian$6.x, scratchCartesian$6.y, scratchCartesian$6.z];
    }

    var result = new Array(length);
    for (var i = 0; i < length; i += 4) {
      result[i] = cartographicDegrees[i];

      scratchCartographic$8.longitude = CesiumMath.toRadians(
        cartographicDegrees[i + 1]
      );
      scratchCartographic$8.latitude = CesiumMath.toRadians(
        cartographicDegrees[i + 2]
      );
      scratchCartographic$8.height = cartographicDegrees[i + 3];
      Ellipsoid.WGS84.cartographicToCartesian(
        scratchCartographic$8,
        scratchCartesian$6
      );

      result[i + 1] = scratchCartesian$6.x;
      result[i + 2] = scratchCartesian$6.y;
      result[i + 3] = scratchCartesian$6.z;
    }
    return result;
  }

  function unwrapCartesianInterval(czmlInterval) {
    var cartesian = czmlInterval.cartesian;
    if (defined(cartesian)) {
      return cartesian;
    }

    var cartesianVelocity = czmlInterval.cartesianVelocity;
    if (defined(cartesianVelocity)) {
      return cartesianVelocity;
    }

    var unitCartesian = czmlInterval.unitCartesian;
    if (defined(unitCartesian)) {
      return unitCartesian;
    }

    var unitSpherical = czmlInterval.unitSpherical;
    if (defined(unitSpherical)) {
      return convertUnitSphericalToCartesian(unitSpherical);
    }

    var spherical = czmlInterval.spherical;
    if (defined(spherical)) {
      return convertSphericalToCartesian(spherical);
    }

    var cartographicRadians = czmlInterval.cartographicRadians;
    if (defined(cartographicRadians)) {
      return convertCartographicRadiansToCartesian(cartographicRadians);
    }

    var cartographicDegrees = czmlInterval.cartographicDegrees;
    if (defined(cartographicDegrees)) {
      return convertCartographicDegreesToCartesian(cartographicDegrees);
    }

    throw new RuntimeError(
      JSON.stringify(czmlInterval) + " is not a valid CZML interval."
    );
  }

  function normalizePackedCartesianArray(array, startingIndex) {
    Cartesian3.unpack(array, startingIndex, scratchCartesian$6);
    Cartesian3.normalize(scratchCartesian$6, scratchCartesian$6);
    Cartesian3.pack(scratchCartesian$6, array, startingIndex);
  }

  function unwrapUnitCartesianInterval(czmlInterval) {
    var cartesian = unwrapCartesianInterval(czmlInterval);
    if (cartesian.length === 3) {
      normalizePackedCartesianArray(cartesian, 0);
      return cartesian;
    }

    for (var i = 1; i < cartesian.length; i += 4) {
      normalizePackedCartesianArray(cartesian, i);
    }

    return cartesian;
  }

  function normalizePackedQuaternionArray(array, startingIndex) {
    Quaternion.unpack(array, startingIndex, scratchQuaternion);
    Quaternion.normalize(scratchQuaternion, scratchQuaternion);
    Quaternion.pack(scratchQuaternion, array, startingIndex);
  }

  function unwrapQuaternionInterval(czmlInterval) {
    var unitQuaternion = czmlInterval.unitQuaternion;
    if (defined(unitQuaternion)) {
      if (unitQuaternion.length === 4) {
        normalizePackedQuaternionArray(unitQuaternion, 0);
        return unitQuaternion;
      }

      for (var i = 1; i < unitQuaternion.length; i += 5) {
        normalizePackedQuaternionArray(unitQuaternion, i);
      }
    }
    return unitQuaternion;
  }

  function getPropertyType(czmlInterval) {
    // The associations in this function need to be kept in sync with the
    // associations in unwrapInterval.

    // Intentionally omitted due to conficts in CZML property names:
    // * Image (conflicts with Uri)
    // * Rotation (conflicts with Number)
    //
    // cartesianVelocity is also omitted due to incomplete support for
    // derivative information in CZML properties.
    // (Currently cartesianVelocity is hacked directly into the position processing code)
    if (typeof czmlInterval === "boolean") {
      return Boolean;
    } else if (typeof czmlInterval === "number") {
      return Number;
    } else if (typeof czmlInterval === "string") {
      return String;
    } else if (czmlInterval.hasOwnProperty("array")) {
      return Array;
    } else if (czmlInterval.hasOwnProperty("boolean")) {
      return Boolean;
    } else if (czmlInterval.hasOwnProperty("boundingRectangle")) {
      return BoundingRectangle;
    } else if (czmlInterval.hasOwnProperty("cartesian2")) {
      return Cartesian2;
    } else if (
      czmlInterval.hasOwnProperty("cartesian") ||
      czmlInterval.hasOwnProperty("spherical") ||
      czmlInterval.hasOwnProperty("cartographicRadians") ||
      czmlInterval.hasOwnProperty("cartographicDegrees")
    ) {
      return Cartesian3;
    } else if (
      czmlInterval.hasOwnProperty("unitCartesian") ||
      czmlInterval.hasOwnProperty("unitSpherical")
    ) {
      return UnitCartesian3;
    } else if (
      czmlInterval.hasOwnProperty("rgba") ||
      czmlInterval.hasOwnProperty("rgbaf")
    ) {
      return Color;
    } else if (czmlInterval.hasOwnProperty("arcType")) {
      return ArcType$1;
    } else if (czmlInterval.hasOwnProperty("classificationType")) {
      return ClassificationType$1;
    } else if (czmlInterval.hasOwnProperty("colorBlendMode")) {
      return ColorBlendMode$1;
    } else if (czmlInterval.hasOwnProperty("cornerType")) {
      return CornerType$1;
    } else if (czmlInterval.hasOwnProperty("heightReference")) {
      return HeightReference$1;
    } else if (czmlInterval.hasOwnProperty("horizontalOrigin")) {
      return HorizontalOrigin$1;
    } else if (czmlInterval.hasOwnProperty("date")) {
      return JulianDate;
    } else if (czmlInterval.hasOwnProperty("labelStyle")) {
      return LabelStyle$1;
    } else if (czmlInterval.hasOwnProperty("number")) {
      return Number;
    } else if (czmlInterval.hasOwnProperty("nearFarScalar")) {
      return NearFarScalar;
    } else if (czmlInterval.hasOwnProperty("distanceDisplayCondition")) {
      return DistanceDisplayCondition;
    } else if (
      czmlInterval.hasOwnProperty("object") ||
      czmlInterval.hasOwnProperty("value")
    ) {
      return Object;
    } else if (czmlInterval.hasOwnProperty("unitQuaternion")) {
      return Quaternion;
    } else if (czmlInterval.hasOwnProperty("shadowMode")) {
      return ShadowMode$1;
    } else if (czmlInterval.hasOwnProperty("string")) {
      return String;
    } else if (czmlInterval.hasOwnProperty("stripeOrientation")) {
      return StripeOrientation$1;
    } else if (
      czmlInterval.hasOwnProperty("wsen") ||
      czmlInterval.hasOwnProperty("wsenDegrees")
    ) {
      return Rectangle;
    } else if (czmlInterval.hasOwnProperty("uri")) {
      return URI;
    } else if (czmlInterval.hasOwnProperty("verticalOrigin")) {
      return VerticalOrigin$1;
    }
    // fallback case
    return Object;
  }

  function unwrapInterval(type, czmlInterval, sourceUri) {
    // The associations in this function need to be kept in sync with the
    // associations in getPropertyType
    switch (type) {
      case ArcType$1:
        return ArcType$1[defaultValue(czmlInterval.arcType, czmlInterval)];
      case Array:
        return czmlInterval.array;
      case Boolean:
        return defaultValue(czmlInterval["boolean"], czmlInterval);
      case BoundingRectangle:
        return czmlInterval.boundingRectangle;
      case Cartesian2:
        return czmlInterval.cartesian2;
      case Cartesian3:
        return unwrapCartesianInterval(czmlInterval);
      case UnitCartesian3:
        return unwrapUnitCartesianInterval(czmlInterval);
      case Color:
        return unwrapColorInterval(czmlInterval);
      case ClassificationType$1:
        return ClassificationType$1[
          defaultValue(czmlInterval.classificationType, czmlInterval)
        ];
      case ColorBlendMode$1:
        return ColorBlendMode$1[
          defaultValue(czmlInterval.colorBlendMode, czmlInterval)
        ];
      case CornerType$1:
        return CornerType$1[defaultValue(czmlInterval.cornerType, czmlInterval)];
      case HeightReference$1:
        return HeightReference$1[
          defaultValue(czmlInterval.heightReference, czmlInterval)
        ];
      case HorizontalOrigin$1:
        return HorizontalOrigin$1[
          defaultValue(czmlInterval.horizontalOrigin, czmlInterval)
        ];
      case Image:
        return unwrapUriInterval(czmlInterval, sourceUri);
      case JulianDate:
        return JulianDate.fromIso8601(
          defaultValue(czmlInterval.date, czmlInterval)
        );
      case LabelStyle$1:
        return LabelStyle$1[defaultValue(czmlInterval.labelStyle, czmlInterval)];
      case Number:
        return defaultValue(czmlInterval.number, czmlInterval);
      case NearFarScalar:
        return czmlInterval.nearFarScalar;
      case DistanceDisplayCondition:
        return czmlInterval.distanceDisplayCondition;
      case Object:
        return defaultValue(
          defaultValue(czmlInterval.object, czmlInterval.value),
          czmlInterval
        );
      case Quaternion:
        return unwrapQuaternionInterval(czmlInterval);
      case Rotation:
        return defaultValue(czmlInterval.number, czmlInterval);
      case ShadowMode$1:
        return ShadowMode$1[
          defaultValue(
            defaultValue(czmlInterval.shadowMode, czmlInterval.shadows),
            czmlInterval
          )
        ];
      case String:
        return defaultValue(czmlInterval.string, czmlInterval);
      case StripeOrientation$1:
        return StripeOrientation$1[
          defaultValue(czmlInterval.stripeOrientation, czmlInterval)
        ];
      case Rectangle:
        return unwrapRectangleInterval(czmlInterval);
      case URI:
        return unwrapUriInterval(czmlInterval, sourceUri);
      case VerticalOrigin$1:
        return VerticalOrigin$1[
          defaultValue(czmlInterval.verticalOrigin, czmlInterval)
        ];
      default:
        throw new RuntimeError(type);
    }
  }

  var interpolators = {
    HERMITE: HermitePolynomialApproximation,
    LAGRANGE: LagrangePolynomialApproximation,
    LINEAR: LinearApproximation,
  };

  function updateInterpolationSettings(packetData, property) {
    var interpolationAlgorithm = packetData.interpolationAlgorithm;
    var interpolationDegree = packetData.interpolationDegree;
    if (defined(interpolationAlgorithm) || defined(interpolationDegree)) {
      property.setInterpolationOptions({
        interpolationAlgorithm: interpolators[interpolationAlgorithm],
        interpolationDegree: interpolationDegree,
      });
    }

    var forwardExtrapolationType = packetData.forwardExtrapolationType;
    if (defined(forwardExtrapolationType)) {
      property.forwardExtrapolationType =
        ExtrapolationType$1[forwardExtrapolationType];
    }

    var forwardExtrapolationDuration = packetData.forwardExtrapolationDuration;
    if (defined(forwardExtrapolationDuration)) {
      property.forwardExtrapolationDuration = forwardExtrapolationDuration;
    }

    var backwardExtrapolationType = packetData.backwardExtrapolationType;
    if (defined(backwardExtrapolationType)) {
      property.backwardExtrapolationType =
        ExtrapolationType$1[backwardExtrapolationType];
    }

    var backwardExtrapolationDuration = packetData.backwardExtrapolationDuration;
    if (defined(backwardExtrapolationDuration)) {
      property.backwardExtrapolationDuration = backwardExtrapolationDuration;
    }
  }

  var iso8601Scratch = {
    iso8601: undefined,
  };

  function intervalFromString(intervalString) {
    if (!defined(intervalString)) {
      return undefined;
    }
    iso8601Scratch.iso8601 = intervalString;
    return TimeInterval.fromIso8601(iso8601Scratch);
  }

  function wrapPropertyInInfiniteInterval(property) {
    var interval = Iso8601.MAXIMUM_INTERVAL.clone();
    interval.data = property;
    return interval;
  }

  function convertPropertyToComposite(property) {
    // Create the composite and add the old property, wrapped in an infinite interval.
    var composite = new CompositeProperty();
    composite.intervals.addInterval(wrapPropertyInInfiniteInterval(property));
    return composite;
  }

  function convertPositionPropertyToComposite(property) {
    // Create the composite and add the old property, wrapped in an infinite interval.
    var composite = new CompositePositionProperty(property.referenceFrame);
    composite.intervals.addInterval(wrapPropertyInInfiniteInterval(property));
    return composite;
  }

  function processProperty(
    type,
    object,
    propertyName,
    packetData,
    constrainedInterval,
    sourceUri,
    entityCollection
  ) {
    var combinedInterval = intervalFromString(packetData.interval);
    if (defined(constrainedInterval)) {
      if (defined(combinedInterval)) {
        combinedInterval = TimeInterval.intersect(
          combinedInterval,
          constrainedInterval,
          scratchTimeInterval
        );
      } else {
        combinedInterval = constrainedInterval;
      }
    }

    var packedLength;
    var unwrappedInterval;
    var unwrappedIntervalLength;

    // CZML properties can be defined in many ways.  Most ways represent a structure for
    // encoding a single value (number, string, cartesian, etc.)  Regardless of the value type,
    // if it encodes a single value it will get loaded into a ConstantProperty eventually.
    // Alternatively, there are ways of defining a property that require specialized
    // client-side representation. Currently, these are ReferenceProperty,
    // and client-side velocity computation properties such as VelocityVectorProperty.
    var isValue =
      !defined(packetData.reference) && !defined(packetData.velocityReference);
    var hasInterval =
      defined(combinedInterval) &&
      !combinedInterval.equals(Iso8601.MAXIMUM_INTERVAL);

    if (packetData.delete === true) {
      // If deleting this property for all time, we can simply set to undefined and return.
      if (!hasInterval) {
        object[propertyName] = undefined;
        return;
      }

      // Deleting depends on the type of property we have.
      return removePropertyData(object[propertyName], combinedInterval);
    }

    var isSampled = false;

    if (isValue) {
      unwrappedInterval = unwrapInterval(type, packetData, sourceUri);
      if (!defined(unwrappedInterval)) {
        // not a known value type, bail
        return;
      }
      packedLength = defaultValue(type.packedLength, 1);
      unwrappedIntervalLength = defaultValue(unwrappedInterval.length, 1);
      isSampled =
        !defined(packetData.array) &&
        typeof unwrappedInterval !== "string" &&
        unwrappedIntervalLength > packedLength &&
        type !== Object;
    }

    // Rotation is a special case because it represents a native type (Number)
    // and therefore does not need to be unpacked when loaded as a constant value.
    var needsUnpacking = typeof type.unpack === "function" && type !== Rotation;

    // Any time a constant value is assigned, it completely blows away anything else.
    if (!isSampled && !hasInterval) {
      if (isValue) {
        object[propertyName] = new ConstantProperty(
          needsUnpacking ? type.unpack(unwrappedInterval, 0) : unwrappedInterval
        );
      } else {
        object[propertyName] = createSpecializedProperty(
          type,
          entityCollection,
          packetData
        );
      }
      return;
    }

    var property = object[propertyName];

    var epoch;
    var packetEpoch = packetData.epoch;
    if (defined(packetEpoch)) {
      epoch = JulianDate.fromIso8601(packetEpoch);
    }

    // Without an interval, any sampled value is infinite, meaning it completely
    // replaces any non-sampled property that may exist.
    if (isSampled && !hasInterval) {
      if (!(property instanceof SampledProperty)) {
        object[propertyName] = property = new SampledProperty(type);
      }
      property.addSamplesPackedArray(unwrappedInterval, epoch);
      updateInterpolationSettings(packetData, property);
      return;
    }

    var interval;

    // A constant value with an interval is normally part of a TimeIntervalCollection,
    // However, if the current property is not a time-interval collection, we need
    // to turn it into a Composite, preserving the old data with the new interval.
    if (!isSampled && hasInterval) {
      // Create a new interval for the constant value.
      combinedInterval = combinedInterval.clone();
      if (isValue) {
        combinedInterval.data = needsUnpacking
          ? type.unpack(unwrappedInterval, 0)
          : unwrappedInterval;
      } else {
        combinedInterval.data = createSpecializedProperty(
          type,
          entityCollection,
          packetData
        );
      }

      // If no property exists, simply use a new interval collection
      if (!defined(property)) {
        object[propertyName] = property = isValue
          ? new TimeIntervalCollectionProperty()
          : new CompositeProperty();
      }

      if (isValue && property instanceof TimeIntervalCollectionProperty) {
        // If we created a collection, or it already was one, use it.
        property.intervals.addInterval(combinedInterval);
      } else if (property instanceof CompositeProperty) {
        // If the collection was already a CompositeProperty, use it.
        if (isValue) {
          combinedInterval.data = new ConstantProperty(combinedInterval.data);
        }
        property.intervals.addInterval(combinedInterval);
      } else {
        // Otherwise, create a CompositeProperty but preserve the existing data.
        object[propertyName] = property = convertPropertyToComposite(property);

        // Change the new data to a ConstantProperty and add it.
        if (isValue) {
          combinedInterval.data = new ConstantProperty(combinedInterval.data);
        }
        property.intervals.addInterval(combinedInterval);
      }

      return;
    }

    // isSampled && hasInterval
    if (!defined(property)) {
      object[propertyName] = property = new CompositeProperty();
    }

    // Create a CompositeProperty but preserve the existing data.
    if (!(property instanceof CompositeProperty)) {
      object[propertyName] = property = convertPropertyToComposite(property);
    }

    // Check if the interval already exists in the composite.
    var intervals = property.intervals;
    interval = intervals.findInterval(combinedInterval);
    if (!defined(interval) || !(interval.data instanceof SampledProperty)) {
      // If not, create a SampledProperty for it.
      interval = combinedInterval.clone();
      interval.data = new SampledProperty(type);
      intervals.addInterval(interval);
    }
    interval.data.addSamplesPackedArray(unwrappedInterval, epoch);
    updateInterpolationSettings(packetData, interval.data);
  }

  function removePropertyData(property, interval) {
    if (property instanceof SampledProperty) {
      property.removeSamples(interval);
      return;
    } else if (property instanceof TimeIntervalCollectionProperty) {
      property.intervals.removeInterval(interval);
      return;
    } else if (property instanceof CompositeProperty) {
      var intervals = property.intervals;
      for (var i = 0; i < intervals.length; ++i) {
        var intersection = TimeInterval.intersect(
          intervals.get(i),
          interval,
          scratchTimeInterval
        );
        if (!intersection.isEmpty) {
          // remove data from the contained properties
          removePropertyData(intersection.data, interval);
        }
      }
      // remove the intervals from the composite
      intervals.removeInterval(interval);
      return;
    }
  }

  function processPacketData(
    type,
    object,
    propertyName,
    packetData,
    interval,
    sourceUri,
    entityCollection
  ) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, len = packetData.length; i < len; ++i) {
        processProperty(
          type,
          object,
          propertyName,
          packetData[i],
          interval,
          sourceUri,
          entityCollection
        );
      }
    } else {
      processProperty(
        type,
        object,
        propertyName,
        packetData,
        interval,
        sourceUri,
        entityCollection
      );
    }
  }

  function processPositionProperty(
    object,
    propertyName,
    packetData,
    constrainedInterval,
    sourceUri,
    entityCollection
  ) {
    var combinedInterval = intervalFromString(packetData.interval);
    if (defined(constrainedInterval)) {
      if (defined(combinedInterval)) {
        combinedInterval = TimeInterval.intersect(
          combinedInterval,
          constrainedInterval,
          scratchTimeInterval
        );
      } else {
        combinedInterval = constrainedInterval;
      }
    }

    var numberOfDerivatives = defined(packetData.cartesianVelocity) ? 1 : 0;
    var packedLength = Cartesian3.packedLength * (numberOfDerivatives + 1);
    var unwrappedInterval;
    var unwrappedIntervalLength;
    var isValue = !defined(packetData.reference);
    var hasInterval =
      defined(combinedInterval) &&
      !combinedInterval.equals(Iso8601.MAXIMUM_INTERVAL);

    if (packetData.delete === true) {
      // If deleting this property for all time, we can simply set to undefined and return.
      if (!hasInterval) {
        object[propertyName] = undefined;
        return;
      }

      // Deleting depends on the type of property we have.
      return removePositionPropertyData(object[propertyName], combinedInterval);
    }

    var referenceFrame;
    var isSampled = false;

    if (isValue) {
      if (defined(packetData.referenceFrame)) {
        referenceFrame = ReferenceFrame$1[packetData.referenceFrame];
      }
      referenceFrame = defaultValue(referenceFrame, ReferenceFrame$1.FIXED);
      unwrappedInterval = unwrapCartesianInterval(packetData);
      unwrappedIntervalLength = defaultValue(unwrappedInterval.length, 1);
      isSampled = unwrappedIntervalLength > packedLength;
    }

    // Any time a constant value is assigned, it completely blows away anything else.
    if (!isSampled && !hasInterval) {
      if (isValue) {
        object[propertyName] = new ConstantPositionProperty(
          Cartesian3.unpack(unwrappedInterval),
          referenceFrame
        );
      } else {
        object[propertyName] = createReferenceProperty(
          entityCollection,
          packetData.reference
        );
      }
      return;
    }

    var property = object[propertyName];

    var epoch;
    var packetEpoch = packetData.epoch;
    if (defined(packetEpoch)) {
      epoch = JulianDate.fromIso8601(packetEpoch);
    }

    // Without an interval, any sampled value is infinite, meaning it completely
    // replaces any non-sampled property that may exist.
    if (isSampled && !hasInterval) {
      if (
        !(property instanceof SampledPositionProperty) ||
        (defined(referenceFrame) && property.referenceFrame !== referenceFrame)
      ) {
        object[propertyName] = property = new SampledPositionProperty(
          referenceFrame,
          numberOfDerivatives
        );
      }
      property.addSamplesPackedArray(unwrappedInterval, epoch);
      updateInterpolationSettings(packetData, property);
      return;
    }

    var interval;

    // A constant value with an interval is normally part of a TimeIntervalCollection,
    // However, if the current property is not a time-interval collection, we need
    // to turn it into a Composite, preserving the old data with the new interval.
    if (!isSampled && hasInterval) {
      // Create a new interval for the constant value.
      combinedInterval = combinedInterval.clone();
      if (isValue) {
        combinedInterval.data = Cartesian3.unpack(unwrappedInterval);
      } else {
        combinedInterval.data = createReferenceProperty(
          entityCollection,
          packetData.reference
        );
      }

      // If no property exists, simply use a new interval collection
      if (!defined(property)) {
        if (isValue) {
          property = new TimeIntervalCollectionPositionProperty(referenceFrame);
        } else {
          property = new CompositePositionProperty(referenceFrame);
        }
        object[propertyName] = property;
      }

      if (
        isValue &&
        property instanceof TimeIntervalCollectionPositionProperty &&
        defined(referenceFrame) &&
        property.referenceFrame === referenceFrame
      ) {
        // If we create a collection, or it already existed, use it.
        property.intervals.addInterval(combinedInterval);
      } else if (property instanceof CompositePositionProperty) {
        // If the collection was already a CompositePositionProperty, use it.
        if (isValue) {
          combinedInterval.data = new ConstantPositionProperty(
            combinedInterval.data,
            referenceFrame
          );
        }
        property.intervals.addInterval(combinedInterval);
      } else {
        // Otherwise, create a CompositePositionProperty but preserve the existing data.
        object[propertyName] = property = convertPositionPropertyToComposite(
          property
        );

        // Change the new data to a ConstantPositionProperty and add it.
        if (isValue) {
          combinedInterval.data = new ConstantPositionProperty(
            combinedInterval.data,
            referenceFrame
          );
        }
        property.intervals.addInterval(combinedInterval);
      }

      return;
    }

    // isSampled && hasInterval
    if (!defined(property)) {
      object[propertyName] = property = new CompositePositionProperty(
        referenceFrame
      );
    } else if (!(property instanceof CompositePositionProperty)) {
      // Create a CompositeProperty but preserve the existing data.
      object[propertyName] = property = convertPositionPropertyToComposite(
        property
      );
    }

    // Check if the interval already exists in the composite.
    var intervals = property.intervals;
    interval = intervals.findInterval(combinedInterval);
    if (
      !defined(interval) ||
      !(interval.data instanceof SampledPositionProperty) ||
      (defined(referenceFrame) && interval.data.referenceFrame !== referenceFrame)
    ) {
      // If not, create a SampledPositionProperty for it.
      interval = combinedInterval.clone();
      interval.data = new SampledPositionProperty(
        referenceFrame,
        numberOfDerivatives
      );
      intervals.addInterval(interval);
    }
    interval.data.addSamplesPackedArray(unwrappedInterval, epoch);
    updateInterpolationSettings(packetData, interval.data);
  }

  function removePositionPropertyData(property, interval) {
    if (property instanceof SampledPositionProperty) {
      property.removeSamples(interval);
      return;
    } else if (property instanceof TimeIntervalCollectionPositionProperty) {
      property.intervals.removeInterval(interval);
      return;
    } else if (property instanceof CompositePositionProperty) {
      var intervals = property.intervals;
      for (var i = 0; i < intervals.length; ++i) {
        var intersection = TimeInterval.intersect(
          intervals.get(i),
          interval,
          scratchTimeInterval
        );
        if (!intersection.isEmpty) {
          // remove data from the contained properties
          removePositionPropertyData(intersection.data, interval);
        }
      }
      // remove the intervals from the composite
      intervals.removeInterval(interval);
      return;
    }
  }

  function processPositionPacketData(
    object,
    propertyName,
    packetData,
    interval,
    sourceUri,
    entityCollection
  ) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, len = packetData.length; i < len; ++i) {
        processPositionProperty(
          object,
          propertyName,
          packetData[i],
          interval,
          sourceUri,
          entityCollection
        );
      }
    } else {
      processPositionProperty(
        object,
        propertyName,
        packetData,
        interval,
        sourceUri,
        entityCollection
      );
    }
  }

  function processShapePacketData(
    object,
    propertyName,
    packetData,
    entityCollection
  ) {
    if (defined(packetData.references)) {
      processReferencesArrayPacketData(
        object,
        propertyName,
        packetData.references,
        packetData.interval,
        entityCollection,
        PropertyArray,
        CompositeProperty
      );
    } else {
      if (defined(packetData.cartesian)) {
        packetData.array = Cartesian2.unpackArray(packetData.cartesian);
      }

      if (defined(packetData.array)) {
        processPacketData(
          Array,
          object,
          propertyName,
          packetData,
          undefined,
          undefined,
          entityCollection
        );
      }
    }
  }

  function processMaterialProperty(
    object,
    propertyName,
    packetData,
    constrainedInterval,
    sourceUri,
    entityCollection
  ) {
    var combinedInterval = intervalFromString(packetData.interval);
    if (defined(constrainedInterval)) {
      if (defined(combinedInterval)) {
        combinedInterval = TimeInterval.intersect(
          combinedInterval,
          constrainedInterval,
          scratchTimeInterval
        );
      } else {
        combinedInterval = constrainedInterval;
      }
    }

    var property = object[propertyName];
    var existingMaterial;
    var existingInterval;

    if (defined(combinedInterval)) {
      if (!(property instanceof CompositeMaterialProperty)) {
        property = new CompositeMaterialProperty();
        object[propertyName] = property;
      }
      //See if we already have data at that interval.
      var thisIntervals = property.intervals;
      existingInterval = thisIntervals.findInterval({
        start: combinedInterval.start,
        stop: combinedInterval.stop,
      });
      if (defined(existingInterval)) {
        //We have an interval, but we need to make sure the
        //new data is the same type of material as the old data.
        existingMaterial = existingInterval.data;
      } else {
        //If not, create it.
        existingInterval = combinedInterval.clone();
        thisIntervals.addInterval(existingInterval);
      }
    } else {
      existingMaterial = property;
    }

    var materialData;
    if (defined(packetData.solidColor)) {
      if (!(existingMaterial instanceof ColorMaterialProperty)) {
        existingMaterial = new ColorMaterialProperty();
      }
      materialData = packetData.solidColor;
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        undefined,
        entityCollection
      );
    } else if (defined(packetData.grid)) {
      if (!(existingMaterial instanceof GridMaterialProperty)) {
        existingMaterial = new GridMaterialProperty();
      }
      materialData = packetData.grid;
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "cellAlpha",
        materialData.cellAlpha,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Cartesian2,
        existingMaterial,
        "lineCount",
        materialData.lineCount,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Cartesian2,
        existingMaterial,
        "lineThickness",
        materialData.lineThickness,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Cartesian2,
        existingMaterial,
        "lineOffset",
        materialData.lineOffset,
        undefined,
        sourceUri,
        entityCollection
      );
    } else if (defined(packetData.image)) {
      if (!(existingMaterial instanceof ImageMaterialProperty)) {
        existingMaterial = new ImageMaterialProperty();
      }
      materialData = packetData.image;
      processPacketData(
        Image,
        existingMaterial,
        "image",
        materialData.image,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Cartesian2,
        existingMaterial,
        "repeat",
        materialData.repeat,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Boolean,
        existingMaterial,
        "transparent",
        materialData.transparent,
        undefined,
        sourceUri,
        entityCollection
      );
    } else if (defined(packetData.stripe)) {
      if (!(existingMaterial instanceof StripeMaterialProperty)) {
        existingMaterial = new StripeMaterialProperty();
      }
      materialData = packetData.stripe;
      processPacketData(
        StripeOrientation$1,
        existingMaterial,
        "orientation",
        materialData.orientation,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Color,
        existingMaterial,
        "evenColor",
        materialData.evenColor,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Color,
        existingMaterial,
        "oddColor",
        materialData.oddColor,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "offset",
        materialData.offset,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "repeat",
        materialData.repeat,
        undefined,
        sourceUri,
        entityCollection
      );
    } else if (defined(packetData.polylineOutline)) {
      if (!(existingMaterial instanceof PolylineOutlineMaterialProperty)) {
        existingMaterial = new PolylineOutlineMaterialProperty();
      }
      materialData = packetData.polylineOutline;
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Color,
        existingMaterial,
        "outlineColor",
        materialData.outlineColor,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "outlineWidth",
        materialData.outlineWidth,
        undefined,
        sourceUri,
        entityCollection
      );
    } else if (defined(packetData.polylineGlow)) {
      if (!(existingMaterial instanceof PolylineGlowMaterialProperty)) {
        existingMaterial = new PolylineGlowMaterialProperty();
      }
      materialData = packetData.polylineGlow;
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "glowPower",
        materialData.glowPower,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "taperPower",
        materialData.taperPower,
        undefined,
        sourceUri,
        entityCollection
      );
    } else if (defined(packetData.polylineArrow)) {
      if (!(existingMaterial instanceof PolylineArrowMaterialProperty)) {
        existingMaterial = new PolylineArrowMaterialProperty();
      }
      materialData = packetData.polylineArrow;
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        undefined,
        entityCollection
      );
    } else if (defined(packetData.polylineDash)) {
      if (!(existingMaterial instanceof PolylineDashMaterialProperty)) {
        existingMaterial = new PolylineDashMaterialProperty();
      }
      materialData = packetData.polylineDash;
      processPacketData(
        Color,
        existingMaterial,
        "color",
        materialData.color,
        undefined,
        undefined,
        entityCollection
      );
      processPacketData(
        Color,
        existingMaterial,
        "gapColor",
        materialData.gapColor,
        undefined,
        undefined,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "dashLength",
        materialData.dashLength,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Number,
        existingMaterial,
        "dashPattern",
        materialData.dashPattern,
        undefined,
        sourceUri,
        entityCollection
      );
    } else if (defined(packetData.checkerboard)) {
      if (!(existingMaterial instanceof CheckerboardMaterialProperty)) {
        existingMaterial = new CheckerboardMaterialProperty();
      }
      materialData = packetData.checkerboard;
      processPacketData(
        Color,
        existingMaterial,
        "evenColor",
        materialData.evenColor,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Color,
        existingMaterial,
        "oddColor",
        materialData.oddColor,
        undefined,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Cartesian2,
        existingMaterial,
        "repeat",
        materialData.repeat,
        undefined,
        sourceUri,
        entityCollection
      );
    }

    if (defined(existingInterval)) {
      existingInterval.data = existingMaterial;
    } else {
      object[propertyName] = existingMaterial;
    }
  }

  function processMaterialPacketData(
    object,
    propertyName,
    packetData,
    interval,
    sourceUri,
    entityCollection
  ) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, len = packetData.length; i < len; ++i) {
        processMaterialProperty(
          object,
          propertyName,
          packetData[i],
          interval,
          sourceUri,
          entityCollection
        );
      }
    } else {
      processMaterialProperty(
        object,
        propertyName,
        packetData,
        interval,
        sourceUri,
        entityCollection
      );
    }
  }

  function processName(entity, packet, entityCollection, sourceUri) {
    var nameData = packet.name;
    if (defined(nameData)) {
      entity.name = packet.name;
    }
  }

  function processDescription(entity, packet, entityCollection, sourceUri) {
    var descriptionData = packet.description;
    if (defined(descriptionData)) {
      processPacketData(
        String,
        entity,
        "description",
        descriptionData,
        undefined,
        sourceUri,
        entityCollection
      );
    }
  }

  function processPosition(entity, packet, entityCollection, sourceUri) {
    var positionData = packet.position;
    if (defined(positionData)) {
      processPositionPacketData(
        entity,
        "position",
        positionData,
        undefined,
        sourceUri,
        entityCollection
      );
    }
  }

  function processViewFrom(entity, packet, entityCollection, sourceUri) {
    var viewFromData = packet.viewFrom;
    if (defined(viewFromData)) {
      processPacketData(
        Cartesian3,
        entity,
        "viewFrom",
        viewFromData,
        undefined,
        sourceUri,
        entityCollection
      );
    }
  }

  function processOrientation(entity, packet, entityCollection, sourceUri) {
    var orientationData = packet.orientation;
    if (defined(orientationData)) {
      processPacketData(
        Quaternion,
        entity,
        "orientation",
        orientationData,
        undefined,
        sourceUri,
        entityCollection
      );
    }
  }

  function processProperties(entity, packet, entityCollection, sourceUri) {
    var propertiesData = packet.properties;
    if (defined(propertiesData)) {
      if (!defined(entity.properties)) {
        entity.properties = new PropertyBag();
      }

      // We cannot simply call processPacketData(entity, 'properties', propertyData, undefined, sourceUri, entityCollection)
      // because each property of "properties" may vary separately.
      // The properties will be accessible as entity.properties.myprop.getValue(time).

      for (var key in propertiesData) {
        if (propertiesData.hasOwnProperty(key)) {
          if (!entity.properties.hasProperty(key)) {
            entity.properties.addProperty(key);
          }

          var propertyData = propertiesData[key];
          if (Array.isArray(propertyData)) {
            for (var i = 0, len = propertyData.length; i < len; ++i) {
              processProperty(
                getPropertyType(propertyData[i]),
                entity.properties,
                key,
                propertyData[i],
                undefined,
                sourceUri,
                entityCollection
              );
            }
          } else {
            processProperty(
              getPropertyType(propertyData),
              entity.properties,
              key,
              propertyData,
              undefined,
              sourceUri,
              entityCollection
            );
          }
        }
      }
    }
  }

  function processReferencesArrayPacketData(
    object,
    propertyName,
    references,
    interval,
    entityCollection,
    PropertyArrayType,
    CompositePropertyArrayType
  ) {
    var properties = references.map(function (reference) {
      return createReferenceProperty(entityCollection, reference);
    });

    if (defined(interval)) {
      interval = intervalFromString(interval);
      var property = object[propertyName];
      if (!(property instanceof CompositePropertyArrayType)) {
        // If the property was not already a CompositeProperty,
        // create a CompositeProperty but preserve the existing data.

        // Create the composite and add the old property, wrapped in an infinite interval.
        var composite = new CompositePropertyArrayType();
        composite.intervals.addInterval(wrapPropertyInInfiniteInterval(property));

        object[propertyName] = property = composite;
      }

      interval.data = new PropertyArrayType(properties);
      property.intervals.addInterval(interval);
    } else {
      object[propertyName] = new PropertyArrayType(properties);
    }
  }

  function processArrayPacketData(
    object,
    propertyName,
    packetData,
    entityCollection
  ) {
    var references = packetData.references;
    if (defined(references)) {
      processReferencesArrayPacketData(
        object,
        propertyName,
        references,
        packetData.interval,
        entityCollection,
        PropertyArray,
        CompositeProperty
      );
    } else {
      processPacketData(
        Array,
        object,
        propertyName,
        packetData,
        undefined,
        undefined,
        entityCollection
      );
    }
  }

  function processArray(object, propertyName, packetData, entityCollection) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, length = packetData.length; i < length; ++i) {
        processArrayPacketData(
          object,
          propertyName,
          packetData[i],
          entityCollection
        );
      }
    } else {
      processArrayPacketData(object, propertyName, packetData, entityCollection);
    }
  }

  function processPositionArrayPacketData(
    object,
    propertyName,
    packetData,
    entityCollection
  ) {
    var references = packetData.references;
    if (defined(references)) {
      processReferencesArrayPacketData(
        object,
        propertyName,
        references,
        packetData.interval,
        entityCollection,
        PositionPropertyArray,
        CompositePositionProperty
      );
    } else {
      if (defined(packetData.cartesian)) {
        packetData.array = Cartesian3.unpackArray(packetData.cartesian);
      } else if (defined(packetData.cartographicRadians)) {
        packetData.array = Cartesian3.fromRadiansArrayHeights(
          packetData.cartographicRadians
        );
      } else if (defined(packetData.cartographicDegrees)) {
        packetData.array = Cartesian3.fromDegreesArrayHeights(
          packetData.cartographicDegrees
        );
      }

      if (defined(packetData.array)) {
        processPacketData(
          Array,
          object,
          propertyName,
          packetData,
          undefined,
          undefined,
          entityCollection
        );
      }
    }
  }

  function processPositionArray(
    object,
    propertyName,
    packetData,
    entityCollection
  ) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, length = packetData.length; i < length; ++i) {
        processPositionArrayPacketData(
          object,
          propertyName,
          packetData[i],
          entityCollection
        );
      }
    } else {
      processPositionArrayPacketData(
        object,
        propertyName,
        packetData,
        entityCollection
      );
    }
  }

  function unpackCartesianArray(array) {
    return Cartesian3.unpackArray(array);
  }

  function unpackCartographicRadiansArray(array) {
    return Cartesian3.fromRadiansArrayHeights(array);
  }

  function unpackCartographicDegreesArray(array) {
    return Cartesian3.fromDegreesArrayHeights(array);
  }

  function processPositionArrayOfArraysPacketData(
    object,
    propertyName,
    packetData,
    entityCollection
  ) {
    var references = packetData.references;
    if (defined(references)) {
      var properties = references.map(function (referenceArray) {
        var tempObj = {};
        processReferencesArrayPacketData(
          tempObj,
          "positions",
          referenceArray,
          packetData.interval,
          entityCollection,
          PositionPropertyArray,
          CompositePositionProperty
        );
        return tempObj.positions;
      });
      object[propertyName] = new PositionPropertyArray(properties);
    } else {
      if (defined(packetData.cartesian)) {
        packetData.array = packetData.cartesian.map(unpackCartesianArray);
      } else if (defined(packetData.cartographicRadians)) {
        packetData.array = packetData.cartographicRadians.map(
          unpackCartographicRadiansArray
        );
      } else if (defined(packetData.cartographicDegrees)) {
        packetData.array = packetData.cartographicDegrees.map(
          unpackCartographicDegreesArray
        );
      }

      if (defined(packetData.array)) {
        processPacketData(
          Array,
          object,
          propertyName,
          packetData,
          undefined,
          undefined,
          entityCollection
        );
      }
    }
  }

  function processPositionArrayOfArrays(
    object,
    propertyName,
    packetData,
    entityCollection
  ) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, length = packetData.length; i < length; ++i) {
        processPositionArrayOfArraysPacketData(
          object,
          propertyName,
          packetData[i],
          entityCollection
        );
      }
    } else {
      processPositionArrayOfArraysPacketData(
        object,
        propertyName,
        packetData,
        entityCollection
      );
    }
  }

  function processShape(object, propertyName, packetData, entityCollection) {
    if (!defined(packetData)) {
      return;
    }

    if (Array.isArray(packetData)) {
      for (var i = 0, length = packetData.length; i < length; i++) {
        processShapePacketData(
          object,
          propertyName,
          packetData[i],
          entityCollection
        );
      }
    } else {
      processShapePacketData(object, propertyName, packetData, entityCollection);
    }
  }

  function processAvailability(entity, packet, entityCollection, sourceUri) {
    var packetData = packet.availability;
    if (!defined(packetData)) {
      return;
    }

    var intervals;
    if (Array.isArray(packetData)) {
      for (var i = 0, len = packetData.length; i < len; ++i) {
        if (!defined(intervals)) {
          intervals = new TimeIntervalCollection();
        }
        intervals.addInterval(intervalFromString(packetData[i]));
      }
    } else {
      intervals = new TimeIntervalCollection();
      intervals.addInterval(intervalFromString(packetData));
    }
    entity.availability = intervals;
  }

  function processAlignedAxis(
    billboard,
    packetData,
    interval,
    sourceUri,
    entityCollection
  ) {
    if (!defined(packetData)) {
      return;
    }

    processPacketData(
      UnitCartesian3,
      billboard,
      "alignedAxis",
      packetData,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processBillboard(entity, packet, entityCollection, sourceUri) {
    var billboardData = packet.billboard;
    if (!defined(billboardData)) {
      return;
    }

    var interval = intervalFromString(billboardData.interval);
    var billboard = entity.billboard;
    if (!defined(billboard)) {
      entity.billboard = billboard = new BillboardGraphics();
    }

    processPacketData(
      Boolean,
      billboard,
      "show",
      billboardData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Image,
      billboard,
      "image",
      billboardData.image,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      billboard,
      "scale",
      billboardData.scale,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian2,
      billboard,
      "pixelOffset",
      billboardData.pixelOffset,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian3,
      billboard,
      "eyeOffset",
      billboardData.eyeOffset,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HorizontalOrigin$1,
      billboard,
      "horizontalOrigin",
      billboardData.horizontalOrigin,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      VerticalOrigin$1,
      billboard,
      "verticalOrigin",
      billboardData.verticalOrigin,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      billboard,
      "heightReference",
      billboardData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      billboard,
      "color",
      billboardData.color,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rotation,
      billboard,
      "rotation",
      billboardData.rotation,
      interval,
      sourceUri,
      entityCollection
    );
    processAlignedAxis(
      billboard,
      billboardData.alignedAxis,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      billboard,
      "sizeInMeters",
      billboardData.sizeInMeters,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      billboard,
      "width",
      billboardData.width,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      billboard,
      "height",
      billboardData.height,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      billboard,
      "scaleByDistance",
      billboardData.scaleByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      billboard,
      "translucencyByDistance",
      billboardData.translucencyByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      billboard,
      "pixelOffsetScaleByDistance",
      billboardData.pixelOffsetScaleByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      BoundingRectangle,
      billboard,
      "imageSubRegion",
      billboardData.imageSubRegion,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      billboard,
      "distanceDisplayCondition",
      billboardData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      billboard,
      "disableDepthTestDistance",
      billboardData.disableDepthTestDistance,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processBox(entity, packet, entityCollection, sourceUri) {
    var boxData = packet.box;
    if (!defined(boxData)) {
      return;
    }

    var interval = intervalFromString(boxData.interval);
    var box = entity.box;
    if (!defined(box)) {
      entity.box = box = new BoxGraphics();
    }

    processPacketData(
      Boolean,
      box,
      "show",
      boxData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian3,
      box,
      "dimensions",
      boxData.dimensions,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      box,
      "heightReference",
      boxData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      box,
      "fill",
      boxData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      box,
      "material",
      boxData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      box,
      "outline",
      boxData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      box,
      "outlineColor",
      boxData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      box,
      "outlineWidth",
      boxData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      box,
      "shadows",
      boxData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      box,
      "distanceDisplayCondition",
      boxData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processCorridor(entity, packet, entityCollection, sourceUri) {
    var corridorData = packet.corridor;
    if (!defined(corridorData)) {
      return;
    }

    var interval = intervalFromString(corridorData.interval);
    var corridor = entity.corridor;
    if (!defined(corridor)) {
      entity.corridor = corridor = new CorridorGraphics();
    }

    processPacketData(
      Boolean,
      corridor,
      "show",
      corridorData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPositionArray(
      corridor,
      "positions",
      corridorData.positions,
      entityCollection
    );
    processPacketData(
      Number,
      corridor,
      "width",
      corridorData.width,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      corridor,
      "height",
      corridorData.height,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      corridor,
      "heightReference",
      corridorData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      corridor,
      "extrudedHeight",
      corridorData.extrudedHeight,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      corridor,
      "extrudedHeightReference",
      corridorData.extrudedHeightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      CornerType$1,
      corridor,
      "cornerType",
      corridorData.cornerType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      corridor,
      "granularity",
      corridorData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      corridor,
      "fill",
      corridorData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      corridor,
      "material",
      corridorData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      corridor,
      "outline",
      corridorData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      corridor,
      "outlineColor",
      corridorData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      corridor,
      "outlineWidth",
      corridorData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      corridor,
      "shadows",
      corridorData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      corridor,
      "distanceDisplayCondition",
      corridorData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ClassificationType$1,
      corridor,
      "classificationType",
      corridorData.classificationType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      corridor,
      "zIndex",
      corridorData.zIndex,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processCylinder(entity, packet, entityCollection, sourceUri) {
    var cylinderData = packet.cylinder;
    if (!defined(cylinderData)) {
      return;
    }

    var interval = intervalFromString(cylinderData.interval);
    var cylinder = entity.cylinder;
    if (!defined(cylinder)) {
      entity.cylinder = cylinder = new CylinderGraphics();
    }

    processPacketData(
      Boolean,
      cylinder,
      "show",
      cylinderData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      cylinder,
      "length",
      cylinderData.length,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      cylinder,
      "topRadius",
      cylinderData.topRadius,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      cylinder,
      "bottomRadius",
      cylinderData.bottomRadius,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      cylinder,
      "heightReference",
      cylinderData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      cylinder,
      "fill",
      cylinderData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      cylinder,
      "material",
      cylinderData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      cylinder,
      "outline",
      cylinderData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      cylinder,
      "outlineColor",
      cylinderData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      cylinder,
      "outlineWidth",
      cylinderData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      cylinder,
      "numberOfVerticalLines",
      cylinderData.numberOfVerticalLines,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      cylinder,
      "slices",
      cylinderData.slices,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      cylinder,
      "shadows",
      cylinderData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      cylinder,
      "distanceDisplayCondition",
      cylinderData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processDocument(packet, dataSource) {
    var version = packet.version;
    if (defined(version)) {
      if (typeof version === "string") {
        var tokens = version.split(".");
        if (tokens.length === 2) {
          if (tokens[0] !== "1") {
            throw new RuntimeError("Cesium only supports CZML version 1.");
          }
          dataSource._version = version;
        }
      }
    }

    if (!defined(dataSource._version)) {
      throw new RuntimeError(
        "CZML version information invalid.  It is expected to be a property on the document object in the <Major>.<Minor> version format."
      );
    }

    var documentPacket = dataSource._documentPacket;

    if (defined(packet.name)) {
      documentPacket.name = packet.name;
    }

    var clockPacket = packet.clock;
    if (defined(clockPacket)) {
      var clock = documentPacket.clock;
      if (!defined(clock)) {
        documentPacket.clock = {
          interval: clockPacket.interval,
          currentTime: clockPacket.currentTime,
          range: clockPacket.range,
          step: clockPacket.step,
          multiplier: clockPacket.multiplier,
        };
      } else {
        clock.interval = defaultValue(clockPacket.interval, clock.interval);
        clock.currentTime = defaultValue(
          clockPacket.currentTime,
          clock.currentTime
        );
        clock.range = defaultValue(clockPacket.range, clock.range);
        clock.step = defaultValue(clockPacket.step, clock.step);
        clock.multiplier = defaultValue(clockPacket.multiplier, clock.multiplier);
      }
    }
  }

  function processEllipse(entity, packet, entityCollection, sourceUri) {
    var ellipseData = packet.ellipse;
    if (!defined(ellipseData)) {
      return;
    }

    var interval = intervalFromString(ellipseData.interval);
    var ellipse = entity.ellipse;
    if (!defined(ellipse)) {
      entity.ellipse = ellipse = new EllipseGraphics();
    }

    processPacketData(
      Boolean,
      ellipse,
      "show",
      ellipseData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "semiMajorAxis",
      ellipseData.semiMajorAxis,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "semiMinorAxis",
      ellipseData.semiMinorAxis,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "height",
      ellipseData.height,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      ellipse,
      "heightReference",
      ellipseData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "extrudedHeight",
      ellipseData.extrudedHeight,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      ellipse,
      "extrudedHeightReference",
      ellipseData.extrudedHeightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rotation,
      ellipse,
      "rotation",
      ellipseData.rotation,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rotation,
      ellipse,
      "stRotation",
      ellipseData.stRotation,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "granularity",
      ellipseData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      ellipse,
      "fill",
      ellipseData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      ellipse,
      "material",
      ellipseData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      ellipse,
      "outline",
      ellipseData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      ellipse,
      "outlineColor",
      ellipseData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "outlineWidth",
      ellipseData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "numberOfVerticalLines",
      ellipseData.numberOfVerticalLines,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      ellipse,
      "shadows",
      ellipseData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      ellipse,
      "distanceDisplayCondition",
      ellipseData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ClassificationType$1,
      ellipse,
      "classificationType",
      ellipseData.classificationType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipse,
      "zIndex",
      ellipseData.zIndex,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processEllipsoid(entity, packet, entityCollection, sourceUri) {
    var ellipsoidData = packet.ellipsoid;
    if (!defined(ellipsoidData)) {
      return;
    }

    var interval = intervalFromString(ellipsoidData.interval);
    var ellipsoid = entity.ellipsoid;
    if (!defined(ellipsoid)) {
      entity.ellipsoid = ellipsoid = new EllipsoidGraphics();
    }

    processPacketData(
      Boolean,
      ellipsoid,
      "show",
      ellipsoidData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian3,
      ellipsoid,
      "radii",
      ellipsoidData.radii,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian3,
      ellipsoid,
      "innerRadii",
      ellipsoidData.innerRadii,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "minimumClock",
      ellipsoidData.minimumClock,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "maximumClock",
      ellipsoidData.maximumClock,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "minimumCone",
      ellipsoidData.minimumCone,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "maximumCone",
      ellipsoidData.maximumCone,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      ellipsoid,
      "heightReference",
      ellipsoidData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      ellipsoid,
      "fill",
      ellipsoidData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      ellipsoid,
      "material",
      ellipsoidData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      ellipsoid,
      "outline",
      ellipsoidData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      ellipsoid,
      "outlineColor",
      ellipsoidData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "outlineWidth",
      ellipsoidData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "stackPartitions",
      ellipsoidData.stackPartitions,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "slicePartitions",
      ellipsoidData.slicePartitions,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      ellipsoid,
      "subdivisions",
      ellipsoidData.subdivisions,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      ellipsoid,
      "shadows",
      ellipsoidData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      ellipsoid,
      "distanceDisplayCondition",
      ellipsoidData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processLabel(entity, packet, entityCollection, sourceUri) {
    var labelData = packet.label;
    if (!defined(labelData)) {
      return;
    }

    var interval = intervalFromString(labelData.interval);
    var label = entity.label;
    if (!defined(label)) {
      entity.label = label = new LabelGraphics();
    }

    processPacketData(
      Boolean,
      label,
      "show",
      labelData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      String,
      label,
      "text",
      labelData.text,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      String,
      label,
      "font",
      labelData.font,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      LabelStyle$1,
      label,
      "style",
      labelData.style,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      label,
      "scale",
      labelData.scale,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      label,
      "showBackground",
      labelData.showBackground,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      label,
      "backgroundColor",
      labelData.backgroundColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian2,
      label,
      "backgroundPadding",
      labelData.backgroundPadding,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian2,
      label,
      "pixelOffset",
      labelData.pixelOffset,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Cartesian3,
      label,
      "eyeOffset",
      labelData.eyeOffset,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HorizontalOrigin$1,
      label,
      "horizontalOrigin",
      labelData.horizontalOrigin,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      VerticalOrigin$1,
      label,
      "verticalOrigin",
      labelData.verticalOrigin,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      label,
      "heightReference",
      labelData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      label,
      "fillColor",
      labelData.fillColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      label,
      "outlineColor",
      labelData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      label,
      "outlineWidth",
      labelData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      label,
      "translucencyByDistance",
      labelData.translucencyByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      label,
      "pixelOffsetScaleByDistance",
      labelData.pixelOffsetScaleByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      label,
      "scaleByDistance",
      labelData.scaleByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      label,
      "distanceDisplayCondition",
      labelData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      label,
      "disableDepthTestDistance",
      labelData.disableDepthTestDistance,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processModel(entity, packet, entityCollection, sourceUri) {
    var modelData = packet.model;
    if (!defined(modelData)) {
      return;
    }

    var interval = intervalFromString(modelData.interval);
    var model = entity.model;
    if (!defined(model)) {
      entity.model = model = new ModelGraphics();
    }

    processPacketData(
      Boolean,
      model,
      "show",
      modelData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      URI,
      model,
      "uri",
      modelData.gltf,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      model,
      "scale",
      modelData.scale,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      model,
      "minimumPixelSize",
      modelData.minimumPixelSize,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      model,
      "maximumScale",
      modelData.maximumScale,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      model,
      "incrementallyLoadTextures",
      modelData.incrementallyLoadTextures,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      model,
      "runAnimations",
      modelData.runAnimations,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      model,
      "clampAnimations",
      modelData.clampAnimations,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      model,
      "shadows",
      modelData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      model,
      "heightReference",
      modelData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      model,
      "silhouetteColor",
      modelData.silhouetteColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      model,
      "silhouetteSize",
      modelData.silhouetteSize,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      model,
      "color",
      modelData.color,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ColorBlendMode$1,
      model,
      "colorBlendMode",
      modelData.colorBlendMode,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      model,
      "colorBlendAmount",
      modelData.colorBlendAmount,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      model,
      "distanceDisplayCondition",
      modelData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );

    var i, len;
    var nodeTransformationsData = modelData.nodeTransformations;
    if (defined(nodeTransformationsData)) {
      if (Array.isArray(nodeTransformationsData)) {
        for (i = 0, len = nodeTransformationsData.length; i < len; ++i) {
          processNodeTransformations(
            model,
            nodeTransformationsData[i],
            interval,
            sourceUri,
            entityCollection
          );
        }
      } else {
        processNodeTransformations(
          model,
          nodeTransformationsData,
          interval,
          sourceUri,
          entityCollection
        );
      }
    }

    var articulationsData = modelData.articulations;
    if (defined(articulationsData)) {
      if (Array.isArray(articulationsData)) {
        for (i = 0, len = articulationsData.length; i < len; ++i) {
          processArticulations(
            model,
            articulationsData[i],
            interval,
            sourceUri,
            entityCollection
          );
        }
      } else {
        processArticulations(
          model,
          articulationsData,
          interval,
          sourceUri,
          entityCollection
        );
      }
    }
  }

  function processNodeTransformations(
    model,
    nodeTransformationsData,
    constrainedInterval,
    sourceUri,
    entityCollection
  ) {
    var combinedInterval = intervalFromString(nodeTransformationsData.interval);
    if (defined(constrainedInterval)) {
      if (defined(combinedInterval)) {
        combinedInterval = TimeInterval.intersect(
          combinedInterval,
          constrainedInterval,
          scratchTimeInterval
        );
      } else {
        combinedInterval = constrainedInterval;
      }
    }

    var nodeTransformations = model.nodeTransformations;
    var nodeNames = Object.keys(nodeTransformationsData);
    for (var i = 0, len = nodeNames.length; i < len; ++i) {
      var nodeName = nodeNames[i];
      if (nodeName === "interval") {
        continue;
      }

      var nodeTransformationData = nodeTransformationsData[nodeName];
      if (!defined(nodeTransformationData)) {
        continue;
      }

      if (!defined(nodeTransformations)) {
        model.nodeTransformations = nodeTransformations = new PropertyBag();
      }

      if (!nodeTransformations.hasProperty(nodeName)) {
        nodeTransformations.addProperty(nodeName);
      }

      var nodeTransformation = nodeTransformations[nodeName];
      if (!defined(nodeTransformation)) {
        nodeTransformations[
          nodeName
        ] = nodeTransformation = new NodeTransformationProperty();
      }

      processPacketData(
        Cartesian3,
        nodeTransformation,
        "translation",
        nodeTransformationData.translation,
        combinedInterval,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Quaternion,
        nodeTransformation,
        "rotation",
        nodeTransformationData.rotation,
        combinedInterval,
        sourceUri,
        entityCollection
      );
      processPacketData(
        Cartesian3,
        nodeTransformation,
        "scale",
        nodeTransformationData.scale,
        combinedInterval,
        sourceUri,
        entityCollection
      );
    }
  }

  function processArticulations(
    model,
    articulationsData,
    constrainedInterval,
    sourceUri,
    entityCollection
  ) {
    var combinedInterval = intervalFromString(articulationsData.interval);
    if (defined(constrainedInterval)) {
      if (defined(combinedInterval)) {
        combinedInterval = TimeInterval.intersect(
          combinedInterval,
          constrainedInterval,
          scratchTimeInterval
        );
      } else {
        combinedInterval = constrainedInterval;
      }
    }

    var articulations = model.articulations;
    var keys = Object.keys(articulationsData);
    for (var i = 0, len = keys.length; i < len; ++i) {
      var key = keys[i];
      if (key === "interval") {
        continue;
      }

      var articulationStageData = articulationsData[key];
      if (!defined(articulationStageData)) {
        continue;
      }

      if (!defined(articulations)) {
        model.articulations = articulations = new PropertyBag();
      }

      if (!articulations.hasProperty(key)) {
        articulations.addProperty(key);
      }

      processPacketData(
        Number,
        articulations,
        key,
        articulationStageData,
        combinedInterval,
        sourceUri,
        entityCollection
      );
    }
  }

  function processPath(entity, packet, entityCollection, sourceUri) {
    var pathData = packet.path;
    if (!defined(pathData)) {
      return;
    }

    var interval = intervalFromString(pathData.interval);
    var path = entity.path;
    if (!defined(path)) {
      entity.path = path = new PathGraphics();
    }

    processPacketData(
      Boolean,
      path,
      "show",
      pathData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      path,
      "leadTime",
      pathData.leadTime,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      path,
      "trailTime",
      pathData.trailTime,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      path,
      "width",
      pathData.width,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      path,
      "resolution",
      pathData.resolution,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      path,
      "material",
      pathData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      path,
      "distanceDisplayCondition",
      pathData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processPoint(entity, packet, entityCollection, sourceUri) {
    var pointData = packet.point;
    if (!defined(pointData)) {
      return;
    }

    var interval = intervalFromString(pointData.interval);
    var point = entity.point;
    if (!defined(point)) {
      entity.point = point = new PointGraphics();
    }

    processPacketData(
      Boolean,
      point,
      "show",
      pointData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      point,
      "pixelSize",
      pointData.pixelSize,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      point,
      "heightReference",
      pointData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      point,
      "color",
      pointData.color,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      point,
      "outlineColor",
      pointData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      point,
      "outlineWidth",
      pointData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      point,
      "scaleByDistance",
      pointData.scaleByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      NearFarScalar,
      point,
      "translucencyByDistance",
      pointData.translucencyByDistance,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      point,
      "distanceDisplayCondition",
      pointData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      point,
      "disableDepthTestDistance",
      pointData.disableDepthTestDistance,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function PolygonHierarchyProperty(polygon) {
    this.polygon = polygon;
    this._definitionChanged = new Event();
  }

  Object.defineProperties(PolygonHierarchyProperty.prototype, {
    isConstant: {
      get: function () {
        var positions = this.polygon._positions;
        var holes = this.polygon._holes;
        return (
          (!defined(positions) || positions.isConstant) &&
          (!defined(holes) || holes.isConstant)
        );
      },
    },
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
  });

  PolygonHierarchyProperty.prototype.getValue = function (time, result) {
    var positions;
    if (defined(this.polygon._positions)) {
      positions = this.polygon._positions.getValue(time);
    }

    var holes;
    if (defined(this.polygon._holes)) {
      holes = this.polygon._holes.getValue(time);
      if (defined(holes)) {
        holes = holes.map(function (holePositions) {
          return new PolygonHierarchy(holePositions);
        });
      }
    }

    if (!defined(result)) {
      return new PolygonHierarchy(positions, holes);
    }

    result.positions = positions;
    result.holes = holes;
    return result;
  };

  PolygonHierarchyProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof PolygonHierarchyProperty &&
        Property.equals(this.polygon._positions, other.polygon._positions) &&
        Property.equals(this.polygon._holes, other.polygon._holes))
    );
  };

  function processPolygon(entity, packet, entityCollection, sourceUri) {
    var polygonData = packet.polygon;
    if (!defined(polygonData)) {
      return;
    }

    var interval = intervalFromString(polygonData.interval);
    var polygon = entity.polygon;
    if (!defined(polygon)) {
      entity.polygon = polygon = new PolygonGraphics();
    }

    processPacketData(
      Boolean,
      polygon,
      "show",
      polygonData.show,
      interval,
      sourceUri,
      entityCollection
    );

    // adapt 'position' property producing Cartesian[]
    // and 'holes' property producing Cartesian[][]
    // to a single property producing PolygonHierarchy
    processPositionArray(
      polygon,
      "_positions",
      polygonData.positions,
      entityCollection
    );
    processPositionArrayOfArrays(
      polygon,
      "_holes",
      polygonData.holes,
      entityCollection
    );
    if (defined(polygon._positions) || defined(polygon._holes)) {
      polygon.hierarchy = new PolygonHierarchyProperty(polygon);
    }

    processPacketData(
      Number,
      polygon,
      "height",
      polygonData.height,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      polygon,
      "heightReference",
      polygonData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polygon,
      "extrudedHeight",
      polygonData.extrudedHeight,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      polygon,
      "extrudedHeightReference",
      polygonData.extrudedHeightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rotation,
      polygon,
      "stRotation",
      polygonData.stRotation,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polygon,
      "granularity",
      polygonData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polygon,
      "fill",
      polygonData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      polygon,
      "material",
      polygonData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polygon,
      "outline",
      polygonData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      polygon,
      "outlineColor",
      polygonData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polygon,
      "outlineWidth",
      polygonData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polygon,
      "perPositionHeight",
      polygonData.perPositionHeight,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polygon,
      "closeTop",
      polygonData.closeTop,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polygon,
      "closeBottom",
      polygonData.closeBottom,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ArcType$1,
      polygon,
      "arcType",
      polygonData.arcType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      polygon,
      "shadows",
      polygonData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      polygon,
      "distanceDisplayCondition",
      polygonData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ClassificationType$1,
      polygon,
      "classificationType",
      polygonData.classificationType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polygon,
      "zIndex",
      polygonData.zIndex,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function adaptFollowSurfaceToArcType(followSurface) {
    return followSurface ? ArcType$1.GEODESIC : ArcType$1.NONE;
  }

  function processPolyline(entity, packet, entityCollection, sourceUri) {
    var polylineData = packet.polyline;
    if (!defined(polylineData)) {
      return;
    }

    var interval = intervalFromString(polylineData.interval);
    var polyline = entity.polyline;
    if (!defined(polyline)) {
      entity.polyline = polyline = new PolylineGraphics();
    }

    processPacketData(
      Boolean,
      polyline,
      "show",
      polylineData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPositionArray(
      polyline,
      "positions",
      polylineData.positions,
      entityCollection
    );
    processPacketData(
      Number,
      polyline,
      "width",
      polylineData.width,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polyline,
      "granularity",
      polylineData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      polyline,
      "material",
      polylineData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      polyline,
      "depthFailMaterial",
      polylineData.depthFailMaterial,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ArcType$1,
      polyline,
      "arcType",
      polylineData.arcType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polyline,
      "clampToGround",
      polylineData.clampToGround,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      polyline,
      "shadows",
      polylineData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      polyline,
      "distanceDisplayCondition",
      polylineData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ClassificationType$1,
      polyline,
      "classificationType",
      polylineData.classificationType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polyline,
      "zIndex",
      polylineData.zIndex,
      interval,
      sourceUri,
      entityCollection
    );

    // for backwards compatibility, adapt CZML followSurface to arcType.
    if (defined(polylineData.followSurface) && !defined(polylineData.arcType)) {
      var tempObj = {};
      processPacketData(
        Boolean,
        tempObj,
        "followSurface",
        polylineData.followSurface,
        interval,
        sourceUri,
        entityCollection
      );
      polyline.arcType = createAdapterProperty(
        tempObj.followSurface,
        adaptFollowSurfaceToArcType
      );
    }
  }

  function processPolylineVolume(entity, packet, entityCollection, sourceUri) {
    var polylineVolumeData = packet.polylineVolume;
    if (!defined(polylineVolumeData)) {
      return;
    }

    var interval = intervalFromString(polylineVolumeData.interval);
    var polylineVolume = entity.polylineVolume;
    if (!defined(polylineVolume)) {
      entity.polylineVolume = polylineVolume = new PolylineVolumeGraphics();
    }

    processPositionArray(
      polylineVolume,
      "positions",
      polylineVolumeData.positions,
      entityCollection
    );
    processShape(
      polylineVolume,
      "shape",
      polylineVolumeData.shape,
      entityCollection
    );
    processPacketData(
      Boolean,
      polylineVolume,
      "show",
      polylineVolumeData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      CornerType$1,
      polylineVolume,
      "cornerType",
      polylineVolumeData.cornerType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polylineVolume,
      "fill",
      polylineVolumeData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      polylineVolume,
      "material",
      polylineVolumeData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      polylineVolume,
      "outline",
      polylineVolumeData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      polylineVolume,
      "outlineColor",
      polylineVolumeData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polylineVolume,
      "outlineWidth",
      polylineVolumeData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      polylineVolume,
      "granularity",
      polylineVolumeData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      polylineVolume,
      "shadows",
      polylineVolumeData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      polylineVolume,
      "distanceDisplayCondition",
      polylineVolumeData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processRectangle(entity, packet, entityCollection, sourceUri) {
    var rectangleData = packet.rectangle;
    if (!defined(rectangleData)) {
      return;
    }

    var interval = intervalFromString(rectangleData.interval);
    var rectangle = entity.rectangle;
    if (!defined(rectangle)) {
      entity.rectangle = rectangle = new RectangleGraphics();
    }

    processPacketData(
      Boolean,
      rectangle,
      "show",
      rectangleData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rectangle,
      rectangle,
      "coordinates",
      rectangleData.coordinates,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      rectangle,
      "height",
      rectangleData.height,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      rectangle,
      "heightReference",
      rectangleData.heightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      rectangle,
      "extrudedHeight",
      rectangleData.extrudedHeight,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      HeightReference$1,
      rectangle,
      "extrudedHeightReference",
      rectangleData.extrudedHeightReference,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rotation,
      rectangle,
      "rotation",
      rectangleData.rotation,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Rotation,
      rectangle,
      "stRotation",
      rectangleData.stRotation,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      rectangle,
      "granularity",
      rectangleData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      rectangle,
      "fill",
      rectangleData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      rectangle,
      "material",
      rectangleData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      rectangle,
      "outline",
      rectangleData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      rectangle,
      "outlineColor",
      rectangleData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      rectangle,
      "outlineWidth",
      rectangleData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      rectangle,
      "shadows",
      rectangleData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      rectangle,
      "distanceDisplayCondition",
      rectangleData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ClassificationType$1,
      rectangle,
      "classificationType",
      rectangleData.classificationType,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      rectangle,
      "zIndex",
      rectangleData.zIndex,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processTileset(entity, packet, entityCollection, sourceUri) {
    var tilesetData = packet.tileset;
    if (!defined(tilesetData)) {
      return;
    }

    var interval = intervalFromString(tilesetData.interval);
    var tileset = entity.tileset;
    if (!defined(tileset)) {
      entity.tileset = tileset = new Cesium3DTilesetGraphics();
    }

    processPacketData(
      Boolean,
      tileset,
      "show",
      tilesetData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      URI,
      tileset,
      "uri",
      tilesetData.uri,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      tileset,
      "maximumScreenSpaceError",
      tilesetData.maximumScreenSpaceError,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processWall(entity, packet, entityCollection, sourceUri) {
    var wallData = packet.wall;
    if (!defined(wallData)) {
      return;
    }

    var interval = intervalFromString(wallData.interval);
    var wall = entity.wall;
    if (!defined(wall)) {
      entity.wall = wall = new WallGraphics();
    }

    processPacketData(
      Boolean,
      wall,
      "show",
      wallData.show,
      interval,
      sourceUri,
      entityCollection
    );
    processPositionArray(wall, "positions", wallData.positions, entityCollection);
    processArray(
      wall,
      "minimumHeights",
      wallData.minimumHeights,
      entityCollection
    );
    processArray(
      wall,
      "maximumHeights",
      wallData.maximumHeights,
      entityCollection
    );
    processPacketData(
      Number,
      wall,
      "granularity",
      wallData.granularity,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      wall,
      "fill",
      wallData.fill,
      interval,
      sourceUri,
      entityCollection
    );
    processMaterialPacketData(
      wall,
      "material",
      wallData.material,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Boolean,
      wall,
      "outline",
      wallData.outline,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Color,
      wall,
      "outlineColor",
      wallData.outlineColor,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      Number,
      wall,
      "outlineWidth",
      wallData.outlineWidth,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      ShadowMode$1,
      wall,
      "shadows",
      wallData.shadows,
      interval,
      sourceUri,
      entityCollection
    );
    processPacketData(
      DistanceDisplayCondition,
      wall,
      "distanceDisplayCondition",
      wallData.distanceDisplayCondition,
      interval,
      sourceUri,
      entityCollection
    );
  }

  function processCzmlPacket(
    packet,
    entityCollection,
    updaterFunctions,
    sourceUri,
    dataSource
  ) {
    var objectId = packet.id;
    if (!defined(objectId)) {
      objectId = createGuid();
    }

    currentId = objectId;

    if (!defined(dataSource._version) && objectId !== "document") {
      throw new RuntimeError(
        "The first CZML packet is required to be the document object."
      );
    }

    if (packet["delete"] === true) {
      entityCollection.removeById(objectId);
    } else if (objectId === "document") {
      processDocument(packet, dataSource);
    } else {
      var entity = entityCollection.getOrCreateEntity(objectId);

      var parentId = packet.parent;
      if (defined(parentId)) {
        entity.parent = entityCollection.getOrCreateEntity(parentId);
      }

      for (var i = updaterFunctions.length - 1; i > -1; i--) {
        updaterFunctions[i](entity, packet, entityCollection, sourceUri);
      }
    }

    currentId = undefined;
  }

  function updateClock(dataSource) {
    var clock;
    var clockPacket = dataSource._documentPacket.clock;
    if (!defined(clockPacket)) {
      if (!defined(dataSource._clock)) {
        var availability = dataSource._entityCollection.computeAvailability();
        if (!availability.start.equals(Iso8601.MINIMUM_VALUE)) {
          var startTime = availability.start;
          var stopTime = availability.stop;
          var totalSeconds = JulianDate.secondsDifference(stopTime, startTime);
          var multiplier = Math.round(totalSeconds / 120.0);

          clock = new DataSourceClock();
          clock.startTime = JulianDate.clone(startTime);
          clock.stopTime = JulianDate.clone(stopTime);
          clock.clockRange = ClockRange$1.LOOP_STOP;
          clock.multiplier = multiplier;
          clock.currentTime = JulianDate.clone(startTime);
          clock.clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;
          dataSource._clock = clock;
          return true;
        }
      }
      return false;
    }

    if (defined(dataSource._clock)) {
      clock = dataSource._clock.clone();
    } else {
      clock = new DataSourceClock();
      clock.startTime = Iso8601.MINIMUM_VALUE.clone();
      clock.stopTime = Iso8601.MAXIMUM_VALUE.clone();
      clock.currentTime = Iso8601.MINIMUM_VALUE.clone();
      clock.clockRange = ClockRange$1.LOOP_STOP;
      clock.clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;
      clock.multiplier = 1.0;
    }

    var interval = intervalFromString(clockPacket.interval);
    if (defined(interval)) {
      clock.startTime = interval.start;
      clock.stopTime = interval.stop;
    }

    if (defined(clockPacket.currentTime)) {
      clock.currentTime = JulianDate.fromIso8601(clockPacket.currentTime);
    }
    if (defined(clockPacket.range)) {
      clock.clockRange = defaultValue(
        ClockRange$1[clockPacket.range],
        ClockRange$1.LOOP_STOP
      );
    }
    if (defined(clockPacket.step)) {
      clock.clockStep = defaultValue(
        ClockStep$1[clockPacket.step],
        ClockStep$1.SYSTEM_CLOCK_MULTIPLIER
      );
    }
    if (defined(clockPacket.multiplier)) {
      clock.multiplier = clockPacket.multiplier;
    }

    if (!clock.equals(dataSource._clock)) {
      dataSource._clock = clock.clone(dataSource._clock);
      return true;
    }

    return false;
  }

  function load(dataSource, czml, options, clear) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(czml)) {
      throw new DeveloperError("czml is required.");
    }
    //>>includeEnd('debug');

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var promise = czml;
    var sourceUri = options.sourceUri;

    // User specified credit
    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    dataSource._credit = credit;

    // If the czml is a URL
    if (typeof czml === "string" || czml instanceof Resource) {
      czml = Resource.createIfNeeded(czml);
      promise = czml.fetchJson();
      sourceUri = defaultValue(sourceUri, czml.clone());

      // Add resource credits to our list of credits to display
      var resourceCredits = dataSource._resourceCredits;
      var credits = czml.credits;
      if (defined(credits)) {
        var length = credits.length;
        for (var i = 0; i < length; i++) {
          resourceCredits.push(credits[i]);
        }
      }
    }

    sourceUri = Resource.createIfNeeded(sourceUri);

    DataSource.setLoading(dataSource, true);

    return when(promise, function (czml) {
      return loadCzml(dataSource, czml, sourceUri, clear);
    }).otherwise(function (error) {
      DataSource.setLoading(dataSource, false);
      dataSource._error.raiseEvent(dataSource, error);
      console.log(error);
      return when.reject(error);
    });
  }

  function loadCzml(dataSource, czml, sourceUri, clear) {
    DataSource.setLoading(dataSource, true);
    var entityCollection = dataSource._entityCollection;

    if (clear) {
      dataSource._version = undefined;
      dataSource._documentPacket = new DocumentPacket();
      entityCollection.removeAll();
    }

    CzmlDataSource._processCzml(
      czml,
      entityCollection,
      sourceUri,
      undefined,
      dataSource
    );

    var raiseChangedEvent = updateClock(dataSource);

    var documentPacket = dataSource._documentPacket;
    if (
      defined(documentPacket.name) &&
      dataSource._name !== documentPacket.name
    ) {
      dataSource._name = documentPacket.name;
      raiseChangedEvent = true;
    } else if (!defined(dataSource._name) && defined(sourceUri)) {
      dataSource._name = getFilenameFromUri(sourceUri.getUrlComponent());
      raiseChangedEvent = true;
    }

    DataSource.setLoading(dataSource, false);
    if (raiseChangedEvent) {
      dataSource._changed.raiseEvent(dataSource);
    }

    return dataSource;
  }

  function DocumentPacket() {
    this.name = undefined;
    this.clock = undefined;
  }

  /**
   * @typedef {Object} CzmlDataSource.LoadOptions
   *
   * Initialization options for the `load` method.
   *
   * @property {Resource|string} [sourceUri] Overrides the url to use for resolving relative links.
   * @property {Credit|string} [credit] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * A {@link DataSource} which processes {@link https://github.com/AnalyticalGraphicsInc/czml-writer/wiki/CZML-Guide|CZML}.
   * @alias CzmlDataSource
   * @constructor
   *
   * @param {String} [name] An optional name for the data source.  This value will be overwritten if a loaded document contains a name.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=CZML.html|Cesium Sandcastle CZML Demo}
   */
  function CzmlDataSource(name) {
    this._name = name;
    this._changed = new Event();
    this._error = new Event();
    this._isLoading = false;
    this._loading = new Event();
    this._clock = undefined;
    this._documentPacket = new DocumentPacket();
    this._version = undefined;
    this._entityCollection = new EntityCollection(this);
    this._entityCluster = new EntityCluster();
    this._credit = undefined;
    this._resourceCredits = [];
  }

  /**
   * Creates a Promise to a new instance loaded with the provided CZML data.
   *
   * @param {Resource|String|Object} czml A url or CZML object to be processed.
   * @param {CzmlDataSource.LoadOptions} [options] An object specifying configuration options
   *
   * @returns {Promise.<CzmlDataSource>} A promise that resolves to the new instance once the data is processed.
   */
  CzmlDataSource.load = function (czml, options) {
    return new CzmlDataSource().load(czml, options);
  };

  Object.defineProperties(CzmlDataSource.prototype, {
    /**
     * Gets a human-readable name for this instance.
     * @memberof CzmlDataSource.prototype
     * @type {String}
     */
    name: {
      get: function () {
        return this._name;
      },
    },
    /**
     * Gets the clock settings defined by the loaded CZML.  If no clock is explicitly
     * defined in the CZML, the combined availability of all objects is returned.  If
     * only static data exists, this value is undefined.
     * @memberof CzmlDataSource.prototype
     * @type {DataSourceClock}
     */
    clock: {
      get: function () {
        return this._clock;
      },
    },
    /**
     * Gets the collection of {@link Entity} instances.
     * @memberof CzmlDataSource.prototype
     * @type {EntityCollection}
     */
    entities: {
      get: function () {
        return this._entityCollection;
      },
    },
    /**
     * Gets a value indicating if the data source is currently loading data.
     * @memberof CzmlDataSource.prototype
     * @type {Boolean}
     */
    isLoading: {
      get: function () {
        return this._isLoading;
      },
    },
    /**
     * Gets an event that will be raised when the underlying data changes.
     * @memberof CzmlDataSource.prototype
     * @type {Event}
     */
    changedEvent: {
      get: function () {
        return this._changed;
      },
    },
    /**
     * Gets an event that will be raised if an error is encountered during processing.
     * @memberof CzmlDataSource.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._error;
      },
    },
    /**
     * Gets an event that will be raised when the data source either starts or stops loading.
     * @memberof CzmlDataSource.prototype
     * @type {Event}
     */
    loadingEvent: {
      get: function () {
        return this._loading;
      },
    },
    /**
     * Gets whether or not this data source should be displayed.
     * @memberof CzmlDataSource.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._entityCollection.show;
      },
      set: function (value) {
        this._entityCollection.show = value;
      },
    },

    /**
     * Gets or sets the clustering options for this data source. This object can be shared between multiple data sources.
     *
     * @memberof CzmlDataSource.prototype
     * @type {EntityCluster}
     */
    clustering: {
      get: function () {
        return this._entityCluster;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value must be defined.");
        }
        //>>includeEnd('debug');
        this._entityCluster = value;
      },
    },
    /**
     * Gets the credit that will be displayed for the data source
     * @memberof CzmlDataSource.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },
  });

  /**
   * Gets the array of CZML processing functions.
   * @memberof CzmlDataSource
   * @type Array
   */
  CzmlDataSource.updaters = [
    processBillboard, //
    processBox, //
    processCorridor, //
    processCylinder, //
    processEllipse, //
    processEllipsoid, //
    processLabel, //
    processModel, //
    processName, //
    processDescription, //
    processPath, //
    processPoint, //
    processPolygon, //
    processPolyline, //
    processPolylineVolume, //
    processProperties, //
    processRectangle, //
    processPosition, //
    processTileset, //
    processViewFrom, //
    processWall, //
    processOrientation, //
    processAvailability,
  ];

  /**
   * Processes the provided url or CZML object without clearing any existing data.
   *
   * @param {Resource|String|Object} czml A url or CZML object to be processed.
   * @param {Object} [options] An object with the following properties:
   * @param {String} [options.sourceUri] Overrides the url to use for resolving relative links.
   * @returns {Promise.<CzmlDataSource>} A promise that resolves to this instances once the data is processed.
   */
  CzmlDataSource.prototype.process = function (czml, options) {
    return load(this, czml, options, false);
  };

  /**
   * Loads the provided url or CZML object, replacing any existing data.
   *
   * @param {Resource|String|Object} czml A url or CZML object to be processed.
   * @param {CzmlDataSource.LoadOptions} [options] An object specifying configuration options

   * @returns {Promise.<CzmlDataSource>} A promise that resolves to this instances once the data is processed.
   */
  CzmlDataSource.prototype.load = function (czml, options) {
    return load(this, czml, options, true);
  };

  /**
   * Updates the data source to the provided time.  This function is optional and
   * is not required to be implemented.  It is provided for data sources which
   * retrieve data based on the current animation time or scene state.
   * If implemented, update will be called by {@link DataSourceDisplay} once a frame.
   *
   * @param {JulianDate} time The simulation time.
   * @returns {Boolean} True if this data source is ready to be displayed at the provided time, false otherwise.
   */
  CzmlDataSource.prototype.update = function (time) {
    return true;
  };

  /**
   * A helper function used by custom CZML updater functions
   * which creates or updates a {@link Property} from a CZML packet.
   * @function
   *
   * @param {Function} type The constructor function for the property being processed.
   * @param {Object} object The object on which the property will be added or updated.
   * @param {String} propertyName The name of the property on the object.
   * @param {Object} packetData The CZML packet being processed.
   * @param {TimeInterval} interval A constraining interval for which the data is valid.
   * @param {String} sourceUri The originating uri of the data being processed.
   * @param {EntityCollection} entityCollection The collection being processsed.
   */
  CzmlDataSource.processPacketData = processPacketData;

  /**
   * A helper function used by custom CZML updater functions
   * which creates or updates a {@link PositionProperty} from a CZML packet.
   * @function
   *
   * @param {Object} object The object on which the property will be added or updated.
   * @param {String} propertyName The name of the property on the object.
   * @param {Object} packetData The CZML packet being processed.
   * @param {TimeInterval} interval A constraining interval for which the data is valid.
   * @param {String} sourceUri The originating uri of the data being processed.
   * @param {EntityCollection} entityCollection The collection being processsed.
   */
  CzmlDataSource.processPositionPacketData = processPositionPacketData;

  /**
   * A helper function used by custom CZML updater functions
   * which creates or updates a {@link MaterialProperty} from a CZML packet.
   * @function
   *
   * @param {Object} object The object on which the property will be added or updated.
   * @param {String} propertyName The name of the property on the object.
   * @param {Object} packetData The CZML packet being processed.
   * @param {TimeInterval} interval A constraining interval for which the data is valid.
   * @param {String} sourceUri The originating uri of the data being processed.
   * @param {EntityCollection} entityCollection The collection being processsed.
   */
  CzmlDataSource.processMaterialPacketData = processMaterialPacketData;

  CzmlDataSource._processCzml = function (
    czml,
    entityCollection,
    sourceUri,
    updaterFunctions,
    dataSource
  ) {
    updaterFunctions = defaultValue(updaterFunctions, CzmlDataSource.updaters);

    if (Array.isArray(czml)) {
      for (var i = 0, len = czml.length; i < len; ++i) {
        processCzmlPacket(
          czml[i],
          entityCollection,
          updaterFunctions,
          sourceUri,
          dataSource
        );
      }
    } else {
      processCzmlPacket(
        czml,
        entityCollection,
        updaterFunctions,
        sourceUri,
        dataSource
      );
    }
  };

  /**
   * A collection of {@link DataSource} instances.
   * @alias DataSourceCollection
   * @constructor
   */
  function DataSourceCollection() {
    this._dataSources = [];
    this._dataSourceAdded = new Event();
    this._dataSourceRemoved = new Event();
    this._dataSourceMoved = new Event();
  }

  Object.defineProperties(DataSourceCollection.prototype, {
    /**
     * Gets the number of data sources in this collection.
     * @memberof DataSourceCollection.prototype
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._dataSources.length;
      },
    },

    /**
     * An event that is raised when a data source is added to the collection.
     * Event handlers are passed the data source that was added.
     * @memberof DataSourceCollection.prototype
     * @type {Event}
     * @readonly
     */
    dataSourceAdded: {
      get: function () {
        return this._dataSourceAdded;
      },
    },

    /**
     * An event that is raised when a data source is removed from the collection.
     * Event handlers are passed the data source that was removed.
     * @memberof DataSourceCollection.prototype
     * @type {Event}
     * @readonly
     */
    dataSourceRemoved: {
      get: function () {
        return this._dataSourceRemoved;
      },
    },

    /**
     * An event that is raised when a data source changes position in the collection.  Event handlers are passed the data source
     * that was moved, its new index after the move, and its old index prior to the move.
     * @memberof DataSourceCollection.prototype
     * @type {Event}
     * @readonly
     */
    dataSourceMoved: {
      get: function () {
        return this._dataSourceMoved;
      },
    },
  });

  /**
   * Adds a data source to the collection.
   *
   * @param {DataSource|Promise.<DataSource>} dataSource A data source or a promise to a data source to add to the collection.
   *                                        When passing a promise, the data source will not actually be added
   *                                        to the collection until the promise resolves successfully.
   * @returns {Promise.<DataSource>} A Promise that resolves once the data source has been added to the collection.
   */
  DataSourceCollection.prototype.add = function (dataSource) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(dataSource)) {
      throw new DeveloperError("dataSource is required.");
    }
    //>>includeEnd('debug');

    var that = this;
    var dataSources = this._dataSources;
    return when(dataSource, function (value) {
      //Only add the data source if removeAll has not been called
      //Since it was added.
      if (dataSources === that._dataSources) {
        that._dataSources.push(value);
        that._dataSourceAdded.raiseEvent(that, value);
      }
      return value;
    });
  };

  /**
   * Removes a data source from this collection, if present.
   *
   * @param {DataSource} dataSource The data source to remove.
   * @param {Boolean} [destroy=false] Whether to destroy the data source in addition to removing it.
   * @returns {Boolean} true if the data source was in the collection and was removed,
   *                    false if the data source was not in the collection.
   */
  DataSourceCollection.prototype.remove = function (dataSource, destroy) {
    destroy = defaultValue(destroy, false);

    var index = this._dataSources.indexOf(dataSource);
    if (index !== -1) {
      this._dataSources.splice(index, 1);
      this._dataSourceRemoved.raiseEvent(this, dataSource);

      if (destroy && typeof dataSource.destroy === "function") {
        dataSource.destroy();
      }

      return true;
    }

    return false;
  };

  /**
   * Removes all data sources from this collection.
   *
   * @param {Boolean} [destroy=false] whether to destroy the data sources in addition to removing them.
   */
  DataSourceCollection.prototype.removeAll = function (destroy) {
    destroy = defaultValue(destroy, false);

    var dataSources = this._dataSources;
    for (var i = 0, len = dataSources.length; i < len; ++i) {
      var dataSource = dataSources[i];
      this._dataSourceRemoved.raiseEvent(this, dataSource);

      if (destroy && typeof dataSource.destroy === "function") {
        dataSource.destroy();
      }
    }
    this._dataSources = [];
  };

  /**
   * Checks to see if the collection contains a given data source.
   *
   * @param {DataSource} dataSource The data source to check for.
   * @returns {Boolean} true if the collection contains the data source, false otherwise.
   */
  DataSourceCollection.prototype.contains = function (dataSource) {
    return this.indexOf(dataSource) !== -1;
  };

  /**
   * Determines the index of a given data source in the collection.
   *
   * @param {DataSource} dataSource The data source to find the index of.
   * @returns {Number} The index of the data source in the collection, or -1 if the data source does not exist in the collection.
   */
  DataSourceCollection.prototype.indexOf = function (dataSource) {
    return this._dataSources.indexOf(dataSource);
  };

  /**
   * Gets a data source by index from the collection.
   *
   * @param {Number} index the index to retrieve.
   * @returns {DataSource} The data source at the specified index.
   */
  DataSourceCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    return this._dataSources[index];
  };

  /**
   * Gets a data source by name from the collection.
   *
   * @param {String} name The name to retrieve.
   * @returns {DataSource[]} A list of all data sources matching the provided name.
   */
  DataSourceCollection.prototype.getByName = function (name) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(name)) {
      throw new DeveloperError("name is required.");
    }
    //>>includeEnd('debug');

    return this._dataSources.filter(function (dataSource) {
      return dataSource.name === name;
    });
  };

  function getIndex(dataSources, dataSource) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(dataSource)) {
      throw new DeveloperError("dataSource is required.");
    }
    //>>includeEnd('debug');

    var index = dataSources.indexOf(dataSource);

    //>>includeStart('debug', pragmas.debug);
    if (index === -1) {
      throw new DeveloperError("dataSource is not in this collection.");
    }
    //>>includeEnd('debug');

    return index;
  }

  function swapDataSources(collection, i, j) {
    var arr = collection._dataSources;
    var length = arr.length - 1;
    i = CesiumMath.clamp(i, 0, length);
    j = CesiumMath.clamp(j, 0, length);

    if (i === j) {
      return;
    }

    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;

    collection.dataSourceMoved.raiseEvent(temp, j, i);
  }

  /**
   * Raises a data source up one position in the collection.
   *
   * @param {DataSource} dataSource The data source to move.
   *
   * @exception {DeveloperError} dataSource is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  DataSourceCollection.prototype.raise = function (dataSource) {
    var index = getIndex(this._dataSources, dataSource);
    swapDataSources(this, index, index + 1);
  };

  /**
   * Lowers a data source down one position in the collection.
   *
   * @param {DataSource} dataSource The data source to move.
   *
   * @exception {DeveloperError} dataSource is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  DataSourceCollection.prototype.lower = function (dataSource) {
    var index = getIndex(this._dataSources, dataSource);
    swapDataSources(this, index, index - 1);
  };

  /**
   * Raises a data source to the top of the collection.
   *
   * @param {DataSource} dataSource The data source to move.
   *
   * @exception {DeveloperError} dataSource is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  DataSourceCollection.prototype.raiseToTop = function (dataSource) {
    var index = getIndex(this._dataSources, dataSource);
    if (index === this._dataSources.length - 1) {
      return;
    }
    this._dataSources.splice(index, 1);
    this._dataSources.push(dataSource);

    this.dataSourceMoved.raiseEvent(
      dataSource,
      this._dataSources.length - 1,
      index
    );
  };

  /**
   * Lowers a data source to the bottom of the collection.
   *
   * @param {DataSource} dataSource The data source to move.
   *
   * @exception {DeveloperError} dataSource is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  DataSourceCollection.prototype.lowerToBottom = function (dataSource) {
    var index = getIndex(this._dataSources, dataSource);
    if (index === 0) {
      return;
    }
    this._dataSources.splice(index, 1);
    this._dataSources.splice(0, 0, dataSource);

    this.dataSourceMoved.raiseEvent(dataSource, 0, index);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} true if this object was destroyed; otherwise, false.
   *
   * @see DataSourceCollection#destroy
   */
  DataSourceCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the resources held by all data sources in this collection.  Explicitly destroying this
   * object allows for deterministic release of WebGL resources, instead of relying on the garbage
   * collector. Once this object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * dataSourceCollection = dataSourceCollection && dataSourceCollection.destroy();
   *
   * @see DataSourceCollection#isDestroyed
   */
  DataSourceCollection.prototype.destroy = function () {
    this.removeAll(true);
    return destroyObject(this);
  };

  /**
   * A collection of primitives.  This is most often used with {@link Scene#primitives},
   * but <code>PrimitiveCollection</code> is also a primitive itself so collections can
   * be added to collections forming a hierarchy.
   *
   * @alias PrimitiveCollection
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.show=true] Determines if the primitives in the collection will be shown.
   * @param {Boolean} [options.destroyPrimitives=true] Determines if primitives in the collection are destroyed when they are removed.
   *
   * @example
   * var billboards = new Cesium.BillboardCollection();
   * var labels = new Cesium.LabelCollection();
   *
   * var collection = new Cesium.PrimitiveCollection();
   * collection.add(billboards);
   *
   * scene.primitives.add(collection);  // Add collection
   * scene.primitives.add(labels);      // Add regular primitive
   */
  function PrimitiveCollection(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._primitives = [];
    this._guid = createGuid();

    // Used by the OrderedGroundPrimitiveCollection
    this._zIndex = undefined;

    /**
     * Determines if primitives in this collection will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * Determines if primitives in the collection are destroyed when they are removed by
     * {@link PrimitiveCollection#destroy} or  {@link PrimitiveCollection#remove} or implicitly
     * by {@link PrimitiveCollection#removeAll}.
     *
     * @type {Boolean}
     * @default true
     *
     * @example
     * // Example 1. Primitives are destroyed by default.
     * var primitives = new Cesium.PrimitiveCollection();
     * var labels = primitives.add(new Cesium.LabelCollection());
     * primitives = primitives.destroy();
     * var b = labels.isDestroyed(); // true
     *
     * @example
     * // Example 2. Do not destroy primitives in a collection.
     * var primitives = new Cesium.PrimitiveCollection();
     * primitives.destroyPrimitives = false;
     * var labels = primitives.add(new Cesium.LabelCollection());
     * primitives = primitives.destroy();
     * var b = labels.isDestroyed(); // false
     * labels = labels.destroy();    // explicitly destroy
     */
    this.destroyPrimitives = defaultValue(options.destroyPrimitives, true);
  }

  Object.defineProperties(PrimitiveCollection.prototype, {
    /**
     * Gets the number of primitives in the collection.
     *
     * @memberof PrimitiveCollection.prototype
     *
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._primitives.length;
      },
    },
  });

  /**
   * Adds a primitive to the collection.
   *
   * @param {Object} primitive The primitive to add.
   * @param {Number} [index] the index to add the layer at.  If omitted, the primitive will
   *                         added at the bottom  of all existing primitives.
   * @returns {Object} The primitive added to the collection.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * var billboards = scene.primitives.add(new Cesium.BillboardCollection());
   */
  PrimitiveCollection.prototype.add = function (primitive, index) {
    var hasIndex = defined(index);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(primitive)) {
      throw new DeveloperError("primitive is required.");
    }
    if (hasIndex) {
      if (index < 0) {
        throw new DeveloperError("index must be greater than or equal to zero.");
      } else if (index > this._primitives.length) {
        throw new DeveloperError(
          "index must be less than or equal to the number of primitives."
        );
      }
    }
    //>>includeEnd('debug');

    var external = (primitive._external = primitive._external || {});
    var composites = (external._composites = external._composites || {});
    composites[this._guid] = {
      collection: this,
    };

    if (!hasIndex) {
      this._primitives.push(primitive);
    } else {
      this._primitives.splice(index, 0, primitive);
    }

    return primitive;
  };

  /**
   * Removes a primitive from the collection.
   *
   * @param {Object} [primitive] The primitive to remove.
   * @returns {Boolean} <code>true</code> if the primitive was removed; <code>false</code> if the primitive is <code>undefined</code> or was not found in the collection.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * var billboards = scene.primitives.add(new Cesium.BillboardCollection());
   * scene.primitives.remove(billboards);  // Returns true
   *
   * @see PrimitiveCollection#destroyPrimitives
   */
  PrimitiveCollection.prototype.remove = function (primitive) {
    // PERFORMANCE_IDEA:  We can obviously make this a lot faster.
    if (this.contains(primitive)) {
      var index = this._primitives.indexOf(primitive);
      if (index !== -1) {
        this._primitives.splice(index, 1);

        delete primitive._external._composites[this._guid];

        if (this.destroyPrimitives) {
          primitive.destroy();
        }

        return true;
      }
      // else ... this is not possible, I swear.
    }

    return false;
  };

  /**
   * Removes and destroys a primitive, regardless of destroyPrimitives setting.
   * @private
   */
  PrimitiveCollection.prototype.removeAndDestroy = function (primitive) {
    var removed = this.remove(primitive);
    if (removed && !this.destroyPrimitives) {
      primitive.destroy();
    }
    return removed;
  };

  /**
   * Removes all primitives in the collection.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PrimitiveCollection#destroyPrimitives
   */
  PrimitiveCollection.prototype.removeAll = function () {
    var primitives = this._primitives;
    var length = primitives.length;
    for (var i = 0; i < length; ++i) {
      delete primitives[i]._external._composites[this._guid];
      if (this.destroyPrimitives) {
        primitives[i].destroy();
      }
    }
    this._primitives = [];
  };

  /**
   * Determines if this collection contains a primitive.
   *
   * @param {Object} [primitive] The primitive to check for.
   * @returns {Boolean} <code>true</code> if the primitive is in the collection; <code>false</code> if the primitive is <code>undefined</code> or was not found in the collection.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PrimitiveCollection#get
   */
  PrimitiveCollection.prototype.contains = function (primitive) {
    return !!(
      defined(primitive) &&
      primitive._external &&
      primitive._external._composites &&
      primitive._external._composites[this._guid]
    );
  };

  function getPrimitiveIndex(compositePrimitive, primitive) {
    //>>includeStart('debug', pragmas.debug);
    if (!compositePrimitive.contains(primitive)) {
      throw new DeveloperError("primitive is not in this collection.");
    }
    //>>includeEnd('debug');

    return compositePrimitive._primitives.indexOf(primitive);
  }

  /**
   * Raises a primitive "up one" in the collection.  If all primitives in the collection are drawn
   * on the globe surface, this visually moves the primitive up one.
   *
   * @param {Object} [primitive] The primitive to raise.
   *
   * @exception {DeveloperError} primitive is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PrimitiveCollection#raiseToTop
   * @see PrimitiveCollection#lower
   * @see PrimitiveCollection#lowerToBottom
   */
  PrimitiveCollection.prototype.raise = function (primitive) {
    if (defined(primitive)) {
      var index = getPrimitiveIndex(this, primitive);
      var primitives = this._primitives;

      if (index !== primitives.length - 1) {
        var p = primitives[index];
        primitives[index] = primitives[index + 1];
        primitives[index + 1] = p;
      }
    }
  };

  /**
   * Raises a primitive to the "top" of the collection.  If all primitives in the collection are drawn
   * on the globe surface, this visually moves the primitive to the top.
   *
   * @param {Object} [primitive] The primitive to raise the top.
   *
   * @exception {DeveloperError} primitive is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PrimitiveCollection#raise
   * @see PrimitiveCollection#lower
   * @see PrimitiveCollection#lowerToBottom
   */
  PrimitiveCollection.prototype.raiseToTop = function (primitive) {
    if (defined(primitive)) {
      var index = getPrimitiveIndex(this, primitive);
      var primitives = this._primitives;

      if (index !== primitives.length - 1) {
        // PERFORMANCE_IDEA:  Could be faster
        primitives.splice(index, 1);
        primitives.push(primitive);
      }
    }
  };

  /**
   * Lowers a primitive "down one" in the collection.  If all primitives in the collection are drawn
   * on the globe surface, this visually moves the primitive down one.
   *
   * @param {Object} [primitive] The primitive to lower.
   *
   * @exception {DeveloperError} primitive is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PrimitiveCollection#lowerToBottom
   * @see PrimitiveCollection#raise
   * @see PrimitiveCollection#raiseToTop
   */
  PrimitiveCollection.prototype.lower = function (primitive) {
    if (defined(primitive)) {
      var index = getPrimitiveIndex(this, primitive);
      var primitives = this._primitives;

      if (index !== 0) {
        var p = primitives[index];
        primitives[index] = primitives[index - 1];
        primitives[index - 1] = p;
      }
    }
  };

  /**
   * Lowers a primitive to the "bottom" of the collection.  If all primitives in the collection are drawn
   * on the globe surface, this visually moves the primitive to the bottom.
   *
   * @param {Object} [primitive] The primitive to lower to the bottom.
   *
   * @exception {DeveloperError} primitive is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PrimitiveCollection#lower
   * @see PrimitiveCollection#raise
   * @see PrimitiveCollection#raiseToTop
   */
  PrimitiveCollection.prototype.lowerToBottom = function (primitive) {
    if (defined(primitive)) {
      var index = getPrimitiveIndex(this, primitive);
      var primitives = this._primitives;

      if (index !== 0) {
        // PERFORMANCE_IDEA:  Could be faster
        primitives.splice(index, 1);
        primitives.unshift(primitive);
      }
    }
  };

  /**
   * Returns the primitive in the collection at the specified index.
   *
   * @param {Number} index The zero-based index of the primitive to return.
   * @returns {Object} The primitive at the <code>index</code>.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * // Toggle the show property of every primitive in the collection.
   * var primitives = scene.primitives;
   * var length = primitives.length;
   * for (var i = 0; i < length; ++i) {
   *   var p = primitives.get(i);
   *   p.show = !p.show;
   * }
   *
   * @see PrimitiveCollection#length
   */
  PrimitiveCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    return this._primitives[index];
  };

  /**
   * @private
   */
  PrimitiveCollection.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    var primitives = this._primitives;
    // Using primitives.length in the loop is a temporary workaround
    // to allow quadtree updates to add and remove primitives in
    // update().  This will be changed to manage added and removed lists.
    for (var i = 0; i < primitives.length; ++i) {
      primitives[i].update(frameState);
    }
  };

  /**
   * @private
   */
  PrimitiveCollection.prototype.prePassesUpdate = function (frameState) {
    var primitives = this._primitives;
    // Using primitives.length in the loop is a temporary workaround
    // to allow quadtree updates to add and remove primitives in
    // update().  This will be changed to manage added and removed lists.
    for (var i = 0; i < primitives.length; ++i) {
      var primitive = primitives[i];
      if (defined(primitive.prePassesUpdate)) {
        primitive.prePassesUpdate(frameState);
      }
    }
  };

  /**
   * @private
   */
  PrimitiveCollection.prototype.updateForPass = function (frameState, passState) {
    var primitives = this._primitives;
    // Using primitives.length in the loop is a temporary workaround
    // to allow quadtree updates to add and remove primitives in
    // update().  This will be changed to manage added and removed lists.
    for (var i = 0; i < primitives.length; ++i) {
      var primitive = primitives[i];
      if (defined(primitive.updateForPass)) {
        primitive.updateForPass(frameState, passState);
      }
    }
  };

  /**
   * @private
   */
  PrimitiveCollection.prototype.postPassesUpdate = function (frameState) {
    var primitives = this._primitives;
    // Using primitives.length in the loop is a temporary workaround
    // to allow quadtree updates to add and remove primitives in
    // update().  This will be changed to manage added and removed lists.
    for (var i = 0; i < primitives.length; ++i) {
      var primitive = primitives[i];
      if (defined(primitive.postPassesUpdate)) {
        primitive.postPassesUpdate(frameState);
      }
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see PrimitiveCollection#destroy
   */
  PrimitiveCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by each primitive in this collection.  Explicitly destroying this
   * collection allows for deterministic release of WebGL resources, instead of relying on the garbage
   * collector to destroy this collection.
   * <br /><br />
   * Since destroying a collection destroys all the contained primitives, only destroy a collection
   * when you are sure no other code is still using any of the contained primitives.
   * <br /><br />
   * Once this collection is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * primitives = primitives && primitives.destroy();
   *
   * @see PrimitiveCollection#isDestroyed
   */
  PrimitiveCollection.prototype.destroy = function () {
    this.removeAll();
    return destroyObject(this);
  };

  /**
   * A primitive collection for helping maintain the order or ground primitives based on a z-index
   *
   * @private
   */
  function OrderedGroundPrimitiveCollection() {
    this._length = 0;
    this._collections = {};
    this._collectionsArray = [];

    this.show = true;
  }

  Object.defineProperties(OrderedGroundPrimitiveCollection.prototype, {
    /**
     * Gets the number of primitives in the collection.
     *
     * @memberof OrderedGroundPrimitiveCollection.prototype
     *
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._length;
      },
    },
  });

  /**
   * Adds a primitive to the collection.
   *
   * @param {GroundPrimitive} primitive The primitive to add.
   * @param {Number} [zIndex = 0] The index of the primitive
   * @returns {GroundPrimitive} The primitive added to the collection.
   */
  OrderedGroundPrimitiveCollection.prototype.add = function (primitive, zIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("primitive", primitive);
    if (defined(zIndex)) {
      Check.typeOf.number("zIndex", zIndex);
    }
    //>>includeEnd('debug');

    zIndex = defaultValue(zIndex, 0);
    var collection = this._collections[zIndex];
    if (!defined(collection)) {
      collection = new PrimitiveCollection({ destroyPrimitives: false });
      collection._zIndex = zIndex;
      this._collections[zIndex] = collection;
      var array = this._collectionsArray;
      var i = 0;
      while (i < array.length && array[i]._zIndex < zIndex) {
        i++;
      }
      array.splice(i, 0, collection);
    }

    collection.add(primitive);
    this._length++;
    primitive._zIndex = zIndex;

    return primitive;
  };

  /**
   * Adjusts the z-index
   * @param {GroundPrimitive} primitive
   * @param {Number} zIndex
   */
  OrderedGroundPrimitiveCollection.prototype.set = function (primitive, zIndex) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("primitive", primitive);
    Check.typeOf.number("zIndex", zIndex);
    //>>includeEnd('debug');

    if (zIndex === primitive._zIndex) {
      return primitive;
    }

    this.remove(primitive, true);
    this.add(primitive, zIndex);

    return primitive;
  };

  /**
   * Removes a primitive from the collection.
   *
   * @param {Object} primitive The primitive to remove.
   * @param {Boolean} [doNotDestroy = false]
   * @returns {Boolean} <code>true</code> if the primitive was removed; <code>false</code> if the primitive is <code>undefined</code> or was not found in the collection.
   */
  OrderedGroundPrimitiveCollection.prototype.remove = function (
    primitive,
    doNotDestroy
  ) {
    if (this.contains(primitive)) {
      var index = primitive._zIndex;
      var collection = this._collections[index];
      var result;
      if (doNotDestroy) {
        result = collection.remove(primitive);
      } else {
        result = collection.removeAndDestroy(primitive);
      }

      if (result) {
        this._length--;
      }

      if (collection.length === 0) {
        this._collectionsArray.splice(
          this._collectionsArray.indexOf(collection),
          1
        );
        this._collections[index] = undefined;
        collection.destroy();
      }

      return result;
    }

    return false;
  };

  /**
   * Removes all primitives in the collection.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see OrderedGroundPrimitiveCollection#destroyPrimitives
   */
  OrderedGroundPrimitiveCollection.prototype.removeAll = function () {
    var collections = this._collectionsArray;
    for (var i = 0; i < collections.length; i++) {
      var collection = collections[i];
      collection.destroyPrimitives = true;
      collection.destroy();
    }

    this._collections = {};
    this._collectionsArray = [];
    this._length = 0;
  };

  /**
   * Determines if this collection contains a primitive.
   *
   * @param {Object} primitive The primitive to check for.
   * @returns {Boolean} <code>true</code> if the primitive is in the collection; <code>false</code> if the primitive is <code>undefined</code> or was not found in the collection.
   */
  OrderedGroundPrimitiveCollection.prototype.contains = function (primitive) {
    if (!defined(primitive)) {
      return false;
    }
    var collection = this._collections[primitive._zIndex];
    return defined(collection) && collection.contains(primitive);
  };

  /**
   * @private
   */
  OrderedGroundPrimitiveCollection.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    var collections = this._collectionsArray;
    for (var i = 0; i < collections.length; i++) {
      collections[i].update(frameState);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see OrderedGroundPrimitiveCollection#destroy
   */
  OrderedGroundPrimitiveCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by each primitive in this collection.  Explicitly destroying this
   * collection allows for deterministic release of WebGL resources, instead of relying on the garbage
   * collector to destroy this collection.
   * <br /><br />
   * Since destroying a collection destroys all the contained primitives, only destroy a collection
   * when you are sure no other code is still using any of the contained primitives.
   * <br /><br />
   * Once this collection is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * primitives = primitives && primitives.destroy();
   *
   * @see OrderedGroundPrimitiveCollection#isDestroyed
   */
  OrderedGroundPrimitiveCollection.prototype.destroy = function () {
    this.removeAll();
    return destroyObject(this);
  };

  /**
   * @private
   */
  function DynamicGeometryBatch(primitives, orderedGroundPrimitives) {
    this._primitives = primitives;
    this._orderedGroundPrimitives = orderedGroundPrimitives;
    this._dynamicUpdaters = new AssociativeArray();
  }

  DynamicGeometryBatch.prototype.add = function (time, updater) {
    this._dynamicUpdaters.set(
      updater.id,
      updater.createDynamicUpdater(
        this._primitives,
        this._orderedGroundPrimitives
      )
    );
  };

  DynamicGeometryBatch.prototype.remove = function (updater) {
    var id = updater.id;
    var dynamicUpdater = this._dynamicUpdaters.get(id);
    if (defined(dynamicUpdater)) {
      this._dynamicUpdaters.remove(id);
      dynamicUpdater.destroy();
    }
  };

  DynamicGeometryBatch.prototype.update = function (time) {
    var geometries = this._dynamicUpdaters.values;
    for (var i = 0, len = geometries.length; i < len; i++) {
      geometries[i].update(time);
    }
    return true;
  };

  DynamicGeometryBatch.prototype.removeAllPrimitives = function () {
    var geometries = this._dynamicUpdaters.values;
    for (var i = 0, len = geometries.length; i < len; i++) {
      geometries[i].destroy();
    }
    this._dynamicUpdaters.removeAll();
  };

  DynamicGeometryBatch.prototype.getBoundingSphere = function (updater, result) {
    updater = this._dynamicUpdaters.get(updater.id);
    if (defined(updater) && defined(updater.getBoundingSphere)) {
      return updater.getBoundingSphere(result);
    }
    return BoundingSphereState$1.FAILED;
  };

  var scratchColor$b = new Color();
  var defaultOffset$4 = Cartesian3.ZERO;
  var offsetScratch$6 = new Cartesian3();
  var scratchRectangle$4 = new Rectangle();

  function EllipseGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.center = undefined;
    this.semiMajorAxis = undefined;
    this.semiMinorAxis = undefined;
    this.rotation = undefined;
    this.height = undefined;
    this.extrudedHeight = undefined;
    this.granularity = undefined;
    this.stRotation = undefined;
    this.numberOfVerticalLines = undefined;
    this.offsetAttribute = undefined;
  }

  /**
   * A {@link GeometryUpdater} for ellipses.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias EllipseGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function EllipseGeometryUpdater(entity, scene) {
    GroundGeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new EllipseGeometryOptions(entity),
      geometryPropertyName: "ellipse",
      observedPropertyNames: ["availability", "position", "ellipse"],
    });

    this._onEntityPropertyChanged(entity, "ellipse", entity.ellipse, undefined);
  }

  if (defined(Object.create)) {
    EllipseGeometryUpdater.prototype = Object.create(
      GroundGeometryUpdater.prototype
    );
    EllipseGeometryUpdater.prototype.constructor = EllipseGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  EllipseGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._fillProperty.getValue(time)
      ),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        this._distanceDisplayConditionProperty.getValue(time)
      ),
      offset: undefined,
      color: undefined,
    };

    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$b);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }

    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$4,
          offsetScratch$6
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new EllipseGeometry(this._options),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  EllipseGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$b
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        distanceDisplayCondition
      ),
      offset: undefined,
    };

    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$4,
          offsetScratch$6
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new EllipseOutlineGeometry(this._options),
      attributes: attributes,
    });
  };

  EllipseGeometryUpdater.prototype._computeCenter = function (time, result) {
    return Property.getValueOrUndefined(this._entity.position, time, result);
  };

  EllipseGeometryUpdater.prototype._isHidden = function (entity, ellipse) {
    var position = entity.position;

    return (
      !defined(position) ||
      !defined(ellipse.semiMajorAxis) ||
      !defined(ellipse.semiMinorAxis) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, ellipse)
    );
  };

  EllipseGeometryUpdater.prototype._isDynamic = function (entity, ellipse) {
    return (
      !entity.position.isConstant || //
      !ellipse.semiMajorAxis.isConstant || //
      !ellipse.semiMinorAxis.isConstant || //
      !Property.isConstant(ellipse.rotation) || //
      !Property.isConstant(ellipse.height) || //
      !Property.isConstant(ellipse.extrudedHeight) || //
      !Property.isConstant(ellipse.granularity) || //
      !Property.isConstant(ellipse.stRotation) || //
      !Property.isConstant(ellipse.outlineWidth) || //
      !Property.isConstant(ellipse.numberOfVerticalLines) || //
      !Property.isConstant(ellipse.zIndex) || //
      (this._onTerrain &&
        !Property.isConstant(this._materialProperty) &&
        !(this._materialProperty instanceof ColorMaterialProperty))
    );
  };

  EllipseGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    ellipse
  ) {
    var heightValue = Property.getValueOrUndefined(
      ellipse.height,
      Iso8601.MINIMUM_VALUE
    );
    var heightReferenceValue = Property.getValueOrDefault(
      ellipse.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      ellipse.extrudedHeight,
      Iso8601.MINIMUM_VALUE
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      ellipse.extrudedHeightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    if (defined(extrudedHeightValue) && !defined(heightValue)) {
      heightValue = 0;
    }

    var options = this._options;
    options.vertexFormat =
      this._materialProperty instanceof ColorMaterialProperty
        ? PerInstanceColorAppearance.VERTEX_FORMAT
        : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.center = entity.position.getValue(
      Iso8601.MINIMUM_VALUE,
      options.center
    );
    options.semiMajorAxis = ellipse.semiMajorAxis.getValue(
      Iso8601.MINIMUM_VALUE,
      options.semiMajorAxis
    );
    options.semiMinorAxis = ellipse.semiMinorAxis.getValue(
      Iso8601.MINIMUM_VALUE,
      options.semiMinorAxis
    );
    options.rotation = Property.getValueOrUndefined(
      ellipse.rotation,
      Iso8601.MINIMUM_VALUE
    );
    options.granularity = Property.getValueOrUndefined(
      ellipse.granularity,
      Iso8601.MINIMUM_VALUE
    );
    options.stRotation = Property.getValueOrUndefined(
      ellipse.stRotation,
      Iso8601.MINIMUM_VALUE
    );
    options.numberOfVerticalLines = Property.getValueOrUndefined(
      ellipse.numberOfVerticalLines,
      Iso8601.MINIMUM_VALUE
    );
    options.offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
      heightValue,
      heightReferenceValue,
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    options.height = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        EllipseGeometry.computeRectangle(options, scratchRectangle$4)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  EllipseGeometryUpdater.DynamicGeometryUpdater = DynamicEllipseGeometryUpdater;

  /**
   * @private
   */
  function DynamicEllipseGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicEllipseGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicEllipseGeometryUpdater.prototype.constructor = DynamicEllipseGeometryUpdater;
  }

  DynamicEllipseGeometryUpdater.prototype._isHidden = function (
    entity,
    ellipse,
    time
  ) {
    var options = this._options;
    return (
      !defined(options.center) ||
      !defined(options.semiMajorAxis) ||
      !defined(options.semiMinorAxis) ||
      DynamicGeometryUpdater.prototype._isHidden.call(this, entity, ellipse, time)
    );
  };

  DynamicEllipseGeometryUpdater.prototype._setOptions = function (
    entity,
    ellipse,
    time
  ) {
    var options = this._options;
    var heightValue = Property.getValueOrUndefined(ellipse.height, time);
    var heightReferenceValue = Property.getValueOrDefault(
      ellipse.heightReference,
      time,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      ellipse.extrudedHeight,
      time
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      ellipse.extrudedHeightReference,
      time,
      HeightReference$1.NONE
    );
    if (defined(extrudedHeightValue) && !defined(heightValue)) {
      heightValue = 0;
    }

    options.center = Property.getValueOrUndefined(
      entity.position,
      time,
      options.center
    );
    options.semiMajorAxis = Property.getValueOrUndefined(
      ellipse.semiMajorAxis,
      time
    );
    options.semiMinorAxis = Property.getValueOrUndefined(
      ellipse.semiMinorAxis,
      time
    );
    options.rotation = Property.getValueOrUndefined(ellipse.rotation, time);
    options.granularity = Property.getValueOrUndefined(ellipse.granularity, time);
    options.stRotation = Property.getValueOrUndefined(ellipse.stRotation, time);
    options.numberOfVerticalLines = Property.getValueOrUndefined(
      ellipse.numberOfVerticalLines,
      time
    );
    options.offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
      heightValue,
      heightReferenceValue,
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    options.height = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        EllipseGeometry.computeRectangle(options, scratchRectangle$4)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  var defaultMaterial$1 = new ColorMaterialProperty(Color.WHITE);
  var defaultOffset$5 = Cartesian3.ZERO;

  var offsetScratch$7 = new Cartesian3();
  var radiiScratch = new Cartesian3();
  var innerRadiiScratch = new Cartesian3();
  var scratchColor$c = new Color();
  var unitSphere = new Cartesian3(1, 1, 1);

  function EllipsoidGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.radii = undefined;
    this.innerRadii = undefined;
    this.minimumClock = undefined;
    this.maximumClock = undefined;
    this.minimumCone = undefined;
    this.maximumCone = undefined;
    this.stackPartitions = undefined;
    this.slicePartitions = undefined;
    this.subdivisions = undefined;
    this.offsetAttribute = undefined;
  }

  /**
   * A {@link GeometryUpdater} for ellipsoids.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias EllipsoidGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function EllipsoidGeometryUpdater(entity, scene) {
    GeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new EllipsoidGeometryOptions(entity),
      geometryPropertyName: "ellipsoid",
      observedPropertyNames: [
        "availability",
        "position",
        "orientation",
        "ellipsoid",
      ],
    });

    this._onEntityPropertyChanged(
      entity,
      "ellipsoid",
      entity.ellipsoid,
      undefined
    );
  }

  if (defined(Object.create)) {
    EllipsoidGeometryUpdater.prototype = Object.create(GeometryUpdater.prototype);
    EllipsoidGeometryUpdater.prototype.constructor = EllipsoidGeometryUpdater;
  }

  Object.defineProperties(EllipsoidGeometryUpdater.prototype, {
    /**
     * Gets the terrain offset property
     * @type {TerrainOffsetProperty}
     * @memberof EllipsoidGeometryUpdater.prototype
     * @readonly
     * @private
     */
    terrainOffsetProperty: {
      get: function () {
        return this._terrainOffsetProperty;
      },
    },
  });

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @param {Boolean} [skipModelMatrix=false] Whether to compute a model matrix for the geometry instance
   * @param {Matrix4} [modelMatrixResult] Used to store the result of the model matrix calculation
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  EllipsoidGeometryUpdater.prototype.createFillGeometryInstance = function (
    time,
    skipModelMatrix,
    modelMatrixResult
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var color;
    var show = new ShowGeometryInstanceAttribute(
      isAvailable &&
        entity.isShowing &&
        this._showProperty.getValue(time) &&
        this._fillProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );

    var attributes = {
      show: show,
      distanceDisplayCondition: distanceDisplayConditionAttribute,
      color: undefined,
      offset: undefined,
    };

    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$c);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      color = ColorGeometryInstanceAttribute.fromColor(currentColor);
      attributes.color = color;
    }
    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$5,
          offsetScratch$7
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new EllipsoidGeometry(this._options),
      modelMatrix: skipModelMatrix
        ? undefined
        : entity.computeModelMatrixForHeightReference(
            time,
            entity.ellipsoid.heightReference,
            this._options.radii.z * 0.5,
            this._scene.mapProjection.ellipsoid,
            modelMatrixResult
          ),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @param {Boolean} [skipModelMatrix=false] Whether to compute a model matrix for the geometry instance
   * @param {Matrix4} [modelMatrixResult] Used to store the result of the model matrix calculation
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  EllipsoidGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time,
    skipModelMatrix,
    modelMatrixResult
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$c
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        distanceDisplayCondition
      ),
      offset: undefined,
    };
    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$5,
          offsetScratch$7
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new EllipsoidOutlineGeometry(this._options),
      modelMatrix: skipModelMatrix
        ? undefined
        : entity.computeModelMatrixForHeightReference(
            time,
            entity.ellipsoid.heightReference,
            this._options.radii.z * 0.5,
            this._scene.mapProjection.ellipsoid,
            modelMatrixResult
          ),
      attributes: attributes,
    });
  };

  EllipsoidGeometryUpdater.prototype._computeCenter = function (time, result) {
    return Property.getValueOrUndefined(this._entity.position, time, result);
  };

  EllipsoidGeometryUpdater.prototype._isHidden = function (entity, ellipsoid) {
    return (
      !defined(entity.position) ||
      !defined(ellipsoid.radii) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, ellipsoid)
    );
  };

  EllipsoidGeometryUpdater.prototype._isDynamic = function (entity, ellipsoid) {
    return (
      !entity.position.isConstant || //
      !Property.isConstant(entity.orientation) || //
      !ellipsoid.radii.isConstant || //
      !Property.isConstant(ellipsoid.innerRadii) || //
      !Property.isConstant(ellipsoid.stackPartitions) || //
      !Property.isConstant(ellipsoid.slicePartitions) || //
      !Property.isConstant(ellipsoid.outlineWidth) || //
      !Property.isConstant(ellipsoid.minimumClock) || //
      !Property.isConstant(ellipsoid.maximumClock) || //
      !Property.isConstant(ellipsoid.minimumCone) || //
      !Property.isConstant(ellipsoid.maximumCone) || //
      !Property.isConstant(ellipsoid.subdivisions)
    );
  };

  EllipsoidGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    ellipsoid
  ) {
    var heightReference = Property.getValueOrDefault(
      ellipsoid.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var options = this._options;
    options.vertexFormat =
      this._materialProperty instanceof ColorMaterialProperty
        ? PerInstanceColorAppearance.VERTEX_FORMAT
        : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.radii = ellipsoid.radii.getValue(
      Iso8601.MINIMUM_VALUE,
      options.radii
    );
    options.innerRadii = Property.getValueOrUndefined(
      ellipsoid.innerRadii,
      options.radii
    );
    options.minimumClock = Property.getValueOrUndefined(
      ellipsoid.minimumClock,
      Iso8601.MINIMUM_VALUE
    );
    options.maximumClock = Property.getValueOrUndefined(
      ellipsoid.maximumClock,
      Iso8601.MINIMUM_VALUE
    );
    options.minimumCone = Property.getValueOrUndefined(
      ellipsoid.minimumCone,
      Iso8601.MINIMUM_VALUE
    );
    options.maximumCone = Property.getValueOrUndefined(
      ellipsoid.maximumCone,
      Iso8601.MINIMUM_VALUE
    );
    options.stackPartitions = Property.getValueOrUndefined(
      ellipsoid.stackPartitions,
      Iso8601.MINIMUM_VALUE
    );
    options.slicePartitions = Property.getValueOrUndefined(
      ellipsoid.slicePartitions,
      Iso8601.MINIMUM_VALUE
    );
    options.subdivisions = Property.getValueOrUndefined(
      ellipsoid.subdivisions,
      Iso8601.MINIMUM_VALUE
    );
    options.offsetAttribute =
      heightReference !== HeightReference$1.NONE
        ? GeometryOffsetAttribute$1.ALL
        : undefined;
  };

  EllipsoidGeometryUpdater.prototype._onEntityPropertyChanged = heightReferenceOnEntityPropertyChanged;

  EllipsoidGeometryUpdater.DynamicGeometryUpdater = DynamicEllipsoidGeometryUpdater;

  /**
   * @private
   */
  function DynamicEllipsoidGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );

    this._scene = geometryUpdater._scene;
    this._modelMatrix = new Matrix4();
    this._attributes = undefined;
    this._outlineAttributes = undefined;
    this._lastSceneMode = undefined;
    this._lastShow = undefined;
    this._lastOutlineShow = undefined;
    this._lastOutlineWidth = undefined;
    this._lastOutlineColor = undefined;
    this._lastOffset = new Cartesian3();
    this._material = {};
  }

  if (defined(Object.create)) {
    DynamicEllipsoidGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicEllipsoidGeometryUpdater.prototype.constructor = DynamicEllipsoidGeometryUpdater;
  }

  DynamicEllipsoidGeometryUpdater.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var entity = this._entity;
    var ellipsoid = entity.ellipsoid;
    if (
      !entity.isShowing ||
      !entity.isAvailable(time) ||
      !Property.getValueOrDefault(ellipsoid.show, time, true)
    ) {
      if (defined(this._primitive)) {
        this._primitive.show = false;
      }

      if (defined(this._outlinePrimitive)) {
        this._outlinePrimitive.show = false;
      }
      return;
    }

    var radii = Property.getValueOrUndefined(ellipsoid.radii, time, radiiScratch);
    var modelMatrix = defined(radii)
      ? entity.computeModelMatrixForHeightReference(
          time,
          ellipsoid.heightReference,
          radii.z * 0.5,
          this._scene.mapProjection.ellipsoid,
          this._modelMatrix
        )
      : undefined;
    if (!defined(modelMatrix) || !defined(radii)) {
      if (defined(this._primitive)) {
        this._primitive.show = false;
      }

      if (defined(this._outlinePrimitive)) {
        this._outlinePrimitive.show = false;
      }
      return;
    }

    //Compute attributes and material.
    var showFill = Property.getValueOrDefault(ellipsoid.fill, time, true);
    var showOutline = Property.getValueOrDefault(ellipsoid.outline, time, false);
    var outlineColor = Property.getValueOrClonedDefault(
      ellipsoid.outlineColor,
      time,
      Color.BLACK,
      scratchColor$c
    );
    var material = MaterialProperty.getValue(
      time,
      defaultValue(ellipsoid.material, defaultMaterial$1),
      this._material
    );

    // Check properties that could trigger a primitive rebuild.
    var innerRadii = Property.getValueOrUndefined(
      ellipsoid.innerRadii,
      time,
      innerRadiiScratch
    );
    var minimumClock = Property.getValueOrUndefined(ellipsoid.minimumClock, time);
    var maximumClock = Property.getValueOrUndefined(ellipsoid.maximumClock, time);
    var minimumCone = Property.getValueOrUndefined(ellipsoid.minimumCone, time);
    var maximumCone = Property.getValueOrUndefined(ellipsoid.maximumCone, time);
    var stackPartitions = Property.getValueOrUndefined(
      ellipsoid.stackPartitions,
      time
    );
    var slicePartitions = Property.getValueOrUndefined(
      ellipsoid.slicePartitions,
      time
    );
    var subdivisions = Property.getValueOrUndefined(ellipsoid.subdivisions, time);
    var outlineWidth = Property.getValueOrDefault(
      ellipsoid.outlineWidth,
      time,
      1.0
    );
    var heightReference = Property.getValueOrDefault(
      ellipsoid.heightReference,
      time,
      HeightReference$1.NONE
    );
    var offsetAttribute =
      heightReference !== HeightReference$1.NONE
        ? GeometryOffsetAttribute$1.ALL
        : undefined;

    //In 3D we use a fast path by modifying Primitive.modelMatrix instead of regenerating the primitive every frame.
    //Also check for height reference because this method doesn't work when the height is relative to terrain.
    var sceneMode = this._scene.mode;
    var in3D =
      sceneMode === SceneMode$1.SCENE3D && heightReference === HeightReference$1.NONE;

    var options = this._options;

    var shadows = this._geometryUpdater.shadowsProperty.getValue(time);

    var distanceDisplayConditionProperty = this._geometryUpdater
      .distanceDisplayConditionProperty;
    var distanceDisplayCondition = distanceDisplayConditionProperty.getValue(
      time
    );

    var offset = Property.getValueOrDefault(
      this._geometryUpdater.terrainOffsetProperty,
      time,
      defaultOffset$5,
      offsetScratch$7
    );

    //We only rebuild the primitive if something other than the radii has changed
    //For the radii, we use unit sphere and then deform it with a scale matrix.
    var rebuildPrimitives =
      !in3D ||
      this._lastSceneMode !== sceneMode ||
      !defined(this._primitive) || //
      options.stackPartitions !== stackPartitions ||
      options.slicePartitions !== slicePartitions || //
      (defined(innerRadii) &&
        !Cartesian3.equals(options.innerRadii !== innerRadii)) ||
      options.minimumClock !== minimumClock || //
      options.maximumClock !== maximumClock ||
      options.minimumCone !== minimumCone || //
      options.maximumCone !== maximumCone ||
      options.subdivisions !== subdivisions || //
      this._lastOutlineWidth !== outlineWidth ||
      options.offsetAttribute !== offsetAttribute;

    if (rebuildPrimitives) {
      var primitives = this._primitives;
      primitives.removeAndDestroy(this._primitive);
      primitives.removeAndDestroy(this._outlinePrimitive);
      this._primitive = undefined;
      this._outlinePrimitive = undefined;
      this._lastSceneMode = sceneMode;
      this._lastOutlineWidth = outlineWidth;

      options.stackPartitions = stackPartitions;
      options.slicePartitions = slicePartitions;
      options.subdivisions = subdivisions;
      options.offsetAttribute = offsetAttribute;
      options.radii = Cartesian3.clone(in3D ? unitSphere : radii, options.radii);
      if (defined(innerRadii)) {
        if (in3D) {
          var mag = Cartesian3.magnitude(radii);
          options.innerRadii = Cartesian3.fromElements(
            innerRadii.x / mag,
            innerRadii.y / mag,
            innerRadii.z / mag,
            options.innerRadii
          );
        } else {
          options.innerRadii = Cartesian3.clone(innerRadii, options.innerRadii);
        }
      } else {
        options.innerRadii = undefined;
      }
      options.minimumClock = minimumClock;
      options.maximumClock = maximumClock;
      options.minimumCone = minimumCone;
      options.maximumCone = maximumCone;

      var appearance = new MaterialAppearance({
        material: material,
        translucent: material.isTranslucent(),
        closed: true,
      });
      options.vertexFormat = appearance.vertexFormat;

      var fillInstance = this._geometryUpdater.createFillGeometryInstance(
        time,
        in3D,
        this._modelMatrix
      );

      this._primitive = primitives.add(
        new Primitive({
          geometryInstances: fillInstance,
          appearance: appearance,
          asynchronous: false,
          shadows: shadows,
        })
      );

      var outlineInstance = this._geometryUpdater.createOutlineGeometryInstance(
        time,
        in3D,
        this._modelMatrix
      );
      this._outlinePrimitive = primitives.add(
        new Primitive({
          geometryInstances: outlineInstance,
          appearance: new PerInstanceColorAppearance({
            flat: true,
            translucent: outlineInstance.attributes.color.value[3] !== 255,
            renderState: {
              lineWidth: this._geometryUpdater._scene.clampLineWidth(
                outlineWidth
              ),
            },
          }),
          asynchronous: false,
          shadows: shadows,
        })
      );

      this._lastShow = showFill;
      this._lastOutlineShow = showOutline;
      this._lastOutlineColor = Color.clone(outlineColor, this._lastOutlineColor);
      this._lastDistanceDisplayCondition = distanceDisplayCondition;
      this._lastOffset = Cartesian3.clone(offset, this._lastOffset);
    } else if (this._primitive.ready) {
      //Update attributes only.
      var primitive = this._primitive;
      var outlinePrimitive = this._outlinePrimitive;

      primitive.show = true;
      outlinePrimitive.show = true;
      primitive.appearance.material = material;

      var attributes = this._attributes;
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(entity);
        this._attributes = attributes;
      }
      if (showFill !== this._lastShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          showFill,
          attributes.show
        );
        this._lastShow = showFill;
      }

      var outlineAttributes = this._outlineAttributes;

      if (!defined(outlineAttributes)) {
        outlineAttributes = outlinePrimitive.getGeometryInstanceAttributes(
          entity
        );
        this._outlineAttributes = outlineAttributes;
      }

      if (showOutline !== this._lastOutlineShow) {
        outlineAttributes.show = ShowGeometryInstanceAttribute.toValue(
          showOutline,
          outlineAttributes.show
        );
        this._lastOutlineShow = showOutline;
      }

      if (!Color.equals(outlineColor, this._lastOutlineColor)) {
        outlineAttributes.color = ColorGeometryInstanceAttribute.toValue(
          outlineColor,
          outlineAttributes.color
        );
        Color.clone(outlineColor, this._lastOutlineColor);
      }

      if (
        !DistanceDisplayCondition.equals(
          distanceDisplayCondition,
          this._lastDistanceDisplayCondition
        )
      ) {
        attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
          distanceDisplayCondition,
          attributes.distanceDisplayCondition
        );
        outlineAttributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
          distanceDisplayCondition,
          outlineAttributes.distanceDisplayCondition
        );
        DistanceDisplayCondition.clone(
          distanceDisplayCondition,
          this._lastDistanceDisplayCondition
        );
      }

      if (!Cartesian3.equals(offset, this._lastOffset)) {
        attributes.offset = OffsetGeometryInstanceAttribute.toValue(
          offset,
          attributes.offset
        );
        outlineAttributes.offset = OffsetGeometryInstanceAttribute.toValue(
          offset,
          attributes.offset
        );
        Cartesian3.clone(offset, this._lastOffset);
      }
    }

    if (in3D) {
      //Since we are scaling a unit sphere, we can't let any of the values go to zero.
      //Instead we clamp them to a small value.  To the naked eye, this produces the same results
      //that you get passing EllipsoidGeometry a radii with a zero component.
      radii.x = Math.max(radii.x, 0.001);
      radii.y = Math.max(radii.y, 0.001);
      radii.z = Math.max(radii.z, 0.001);

      modelMatrix = Matrix4.multiplyByScale(modelMatrix, radii, modelMatrix);
      this._primitive.modelMatrix = modelMatrix;
      this._outlinePrimitive.modelMatrix = modelMatrix;
    }
  };

  var positionScratch$9 = new Cartesian3();
  var scratchColor$d = new Color();

  function PlaneGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.plane = undefined;
    this.dimensions = undefined;
  }

  /**
   * A {@link GeometryUpdater} for planes.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias PlaneGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function PlaneGeometryUpdater(entity, scene) {
    GeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new PlaneGeometryOptions(entity),
      geometryPropertyName: "plane",
      observedPropertyNames: ["availability", "position", "orientation", "plane"],
    });

    this._onEntityPropertyChanged(entity, "plane", entity.plane, undefined);
  }

  if (defined(Object.create)) {
    PlaneGeometryUpdater.prototype = Object.create(GeometryUpdater.prototype);
    PlaneGeometryUpdater.prototype.constructor = PlaneGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  PlaneGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var attributes;

    var color;
    var show = new ShowGeometryInstanceAttribute(
      isAvailable &&
        entity.isShowing &&
        this._showProperty.getValue(time) &&
        this._fillProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );
    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$d);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      color = ColorGeometryInstanceAttribute.fromColor(currentColor);
      attributes = {
        show: show,
        distanceDisplayCondition: distanceDisplayConditionAttribute,
        color: color,
      };
    } else {
      attributes = {
        show: show,
        distanceDisplayCondition: distanceDisplayConditionAttribute,
      };
    }

    var planeGraphics = entity.plane;
    var options = this._options;
    var modelMatrix = entity.computeModelMatrix(time);
    var plane = Property.getValueOrDefault(
      planeGraphics.plane,
      time,
      options.plane
    );
    var dimensions = Property.getValueOrUndefined(
      planeGraphics.dimensions,
      time,
      options.dimensions
    );

    options.plane = plane;
    options.dimensions = dimensions;

    modelMatrix = createPrimitiveMatrix(
      plane,
      dimensions,
      modelMatrix,
      this._scene.mapProjection.ellipsoid,
      modelMatrix
    );

    return new GeometryInstance({
      id: entity,
      geometry: new PlaneGeometry(this._options),
      modelMatrix: modelMatrix,
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  PlaneGeometryUpdater.prototype.createOutlineGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$d
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var planeGraphics = entity.plane;
    var options = this._options;
    var modelMatrix = entity.computeModelMatrix(time);
    var plane = Property.getValueOrDefault(
      planeGraphics.plane,
      time,
      options.plane
    );
    var dimensions = Property.getValueOrUndefined(
      planeGraphics.dimensions,
      time,
      options.dimensions
    );

    options.plane = plane;
    options.dimensions = dimensions;

    modelMatrix = createPrimitiveMatrix(
      plane,
      dimensions,
      modelMatrix,
      this._scene.mapProjection.ellipsoid,
      modelMatrix
    );

    return new GeometryInstance({
      id: entity,
      geometry: new PlaneOutlineGeometry(),
      modelMatrix: modelMatrix,
      attributes: {
        show: new ShowGeometryInstanceAttribute(
          isAvailable &&
            entity.isShowing &&
            this._showProperty.getValue(time) &&
            this._showOutlineProperty.getValue(time)
        ),
        color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
        distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
          distanceDisplayCondition
        ),
      },
    });
  };

  PlaneGeometryUpdater.prototype._isHidden = function (entity, plane) {
    return (
      !defined(plane.plane) ||
      !defined(plane.dimensions) ||
      !defined(entity.position) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, plane)
    );
  };

  PlaneGeometryUpdater.prototype._getIsClosed = function (options) {
    return false;
  };

  PlaneGeometryUpdater.prototype._isDynamic = function (entity, plane) {
    return (
      !entity.position.isConstant || //
      !Property.isConstant(entity.orientation) || //
      !plane.plane.isConstant || //
      !plane.dimensions.isConstant || //
      !Property.isConstant(plane.outlineWidth)
    );
  };

  PlaneGeometryUpdater.prototype._setStaticOptions = function (entity, plane) {
    var isColorMaterial = this._materialProperty instanceof ColorMaterialProperty;

    var options = this._options;
    options.vertexFormat = isColorMaterial
      ? PerInstanceColorAppearance.VERTEX_FORMAT
      : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.plane = plane.plane.getValue(Iso8601.MINIMUM_VALUE, options.plane);
    options.dimensions = plane.dimensions.getValue(
      Iso8601.MINIMUM_VALUE,
      options.dimensions
    );
  };

  PlaneGeometryUpdater.DynamicGeometryUpdater = DynamicPlaneGeometryUpdater;

  /**
   * @private
   */
  function DynamicPlaneGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicPlaneGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicPlaneGeometryUpdater.prototype.constructor = DynamicPlaneGeometryUpdater;
  }

  DynamicPlaneGeometryUpdater.prototype._isHidden = function (
    entity,
    plane,
    time
  ) {
    var options = this._options;
    var position = Property.getValueOrUndefined(
      entity.position,
      time,
      positionScratch$9
    );
    return (
      !defined(position) ||
      !defined(options.plane) ||
      !defined(options.dimensions) ||
      DynamicGeometryUpdater.prototype._isHidden.call(this, entity, plane, time)
    );
  };

  DynamicPlaneGeometryUpdater.prototype._setOptions = function (
    entity,
    plane,
    time
  ) {
    var options = this._options;
    options.plane = Property.getValueOrDefault(plane.plane, time, options.plane);
    options.dimensions = Property.getValueOrUndefined(
      plane.dimensions,
      time,
      options.dimensions
    );
  };

  var scratchAxis$1 = new Cartesian3();
  var scratchAxis2 = new Cartesian3();
  var scratchTranslation = new Cartesian3();
  var scratchNormal$7 = new Cartesian3();
  var scratchScale$7 = new Cartesian3();
  var scratchQuaternion$1 = new Quaternion();
  var scratchMatrix3$1 = new Matrix3();
  function createPrimitiveMatrix(
    plane,
    dimensions,
    transform,
    ellipsoid,
    result
  ) {
    var normal = plane.normal;
    var distance = plane.distance;

    var translation = Cartesian3.multiplyByScalar(
      normal,
      -distance,
      scratchTranslation
    );
    translation = Matrix4.multiplyByPoint(transform, translation, translation);

    var transformedNormal = Matrix4.multiplyByPointAsVector(
      transform,
      normal,
      scratchNormal$7
    );
    Cartesian3.normalize(transformedNormal, transformedNormal);

    var up = ellipsoid.geodeticSurfaceNormal(translation, scratchAxis2);
    if (
      CesiumMath.equalsEpsilon(
        Math.abs(Cartesian3.dot(up, transformedNormal)),
        1.0,
        CesiumMath.EPSILON8
      )
    ) {
      up = Cartesian3.clone(Cartesian3.UNIT_Z, up);
      if (
        CesiumMath.equalsEpsilon(
          Math.abs(Cartesian3.dot(up, transformedNormal)),
          1.0,
          CesiumMath.EPSILON8
        )
      ) {
        up = Cartesian3.clone(Cartesian3.UNIT_X, up);
      }
    }

    var left = Cartesian3.cross(up, transformedNormal, scratchAxis$1);
    up = Cartesian3.cross(transformedNormal, left, up);
    Cartesian3.normalize(left, left);
    Cartesian3.normalize(up, up);

    var rotationMatrix = scratchMatrix3$1;
    Matrix3.setColumn(rotationMatrix, 0, left, rotationMatrix);
    Matrix3.setColumn(rotationMatrix, 1, up, rotationMatrix);
    Matrix3.setColumn(rotationMatrix, 2, transformedNormal, rotationMatrix);
    var rotation = Quaternion.fromRotationMatrix(
      rotationMatrix,
      scratchQuaternion$1
    );

    var scale = Cartesian2.clone(dimensions, scratchScale$7);
    scale.z = 1.0;

    return Matrix4.fromTranslationQuaternionRotationScale(
      translation,
      rotation,
      scale,
      result
    );
  }

  /**
   * @private
   */
  PlaneGeometryUpdater.createPrimitiveMatrix = createPrimitiveMatrix;

  var heightAndPerPositionHeightWarning =
    "Entity polygons cannot have both height and perPositionHeight.  height will be ignored";
  var heightReferenceAndPerPositionHeightWarning =
    "heightReference is not supported for entity polygons with perPositionHeight. heightReference will be ignored";

  var scratchColor$e = new Color();
  var defaultOffset$6 = Cartesian3.ZERO;
  var offsetScratch$8 = new Cartesian3();
  var scratchRectangle$5 = new Rectangle();
  var scratch2DPositions = [];
  var cart2Scratch = new Cartesian2();

  function PolygonGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.polygonHierarchy = undefined;
    this.perPositionHeight = undefined;
    this.closeTop = undefined;
    this.closeBottom = undefined;
    this.height = undefined;
    this.extrudedHeight = undefined;
    this.granularity = undefined;
    this.stRotation = undefined;
    this.offsetAttribute = undefined;
    this.arcType = undefined;
  }

  /**
   * A {@link GeometryUpdater} for polygons.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias PolygonGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function PolygonGeometryUpdater(entity, scene) {
    GroundGeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new PolygonGeometryOptions(entity),
      geometryPropertyName: "polygon",
      observedPropertyNames: ["availability", "polygon"],
    });

    this._onEntityPropertyChanged(entity, "polygon", entity.polygon, undefined);
  }

  if (defined(Object.create)) {
    PolygonGeometryUpdater.prototype = Object.create(
      GroundGeometryUpdater.prototype
    );
    PolygonGeometryUpdater.prototype.constructor = PolygonGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  PolygonGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var options = this._options;

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._fillProperty.getValue(time)
      ),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        this._distanceDisplayConditionProperty.getValue(time)
      ),
      offset: undefined,
      color: undefined,
    };

    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$e);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }
    if (defined(options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$6,
          offsetScratch$8
        )
      );
    }

    var geometry;
    if (options.perPositionHeight && !defined(options.extrudedHeight)) {
      geometry = new CoplanarPolygonGeometry(options);
    } else {
      geometry = new PolygonGeometry(options);
    }

    return new GeometryInstance({
      id: entity,
      geometry: geometry,
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  PolygonGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var options = this._options;
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$e
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        distanceDisplayCondition
      ),
      offset: undefined,
    };

    if (defined(options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$6,
          offsetScratch$8
        )
      );
    }

    var geometry;
    if (options.perPositionHeight && !defined(options.extrudedHeight)) {
      geometry = new CoplanarPolygonOutlineGeometry(options);
    } else {
      geometry = new PolygonOutlineGeometry(options);
    }
    return new GeometryInstance({
      id: entity,
      geometry: geometry,
      attributes: attributes,
    });
  };

  PolygonGeometryUpdater.prototype._computeCenter = function (time, result) {
    var hierarchy = Property.getValueOrUndefined(
      this._entity.polygon.hierarchy,
      time
    );
    if (!defined(hierarchy)) {
      return;
    }
    var positions = hierarchy.positions;
    if (positions.length === 0) {
      return;
    }
    var ellipsoid = this._scene.mapProjection.ellipsoid;

    var tangentPlane = EllipsoidTangentPlane.fromPoints(positions, ellipsoid);
    var positions2D = tangentPlane.projectPointsOntoPlane(
      positions,
      scratch2DPositions
    );

    var length = positions2D.length;
    var area = 0;
    var j = length - 1;
    var centroid2D = new Cartesian2();
    for (var i = 0; i < length; j = i++) {
      var p1 = positions2D[i];
      var p2 = positions2D[j];
      var f = p1.x * p2.y - p2.x * p1.y;

      var sum = Cartesian2.add(p1, p2, cart2Scratch);
      sum = Cartesian2.multiplyByScalar(sum, f, sum);
      centroid2D = Cartesian2.add(centroid2D, sum, centroid2D);

      area += f;
    }

    var a = 1.0 / (area * 3.0);
    centroid2D = Cartesian2.multiplyByScalar(centroid2D, a, centroid2D);
    return tangentPlane.projectPointOntoEllipsoid(centroid2D, result);
  };

  PolygonGeometryUpdater.prototype._isHidden = function (entity, polygon) {
    return (
      !defined(polygon.hierarchy) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, polygon)
    );
  };

  PolygonGeometryUpdater.prototype._isOnTerrain = function (entity, polygon) {
    var onTerrain = GroundGeometryUpdater.prototype._isOnTerrain.call(
      this,
      entity,
      polygon
    );
    var perPositionHeightProperty = polygon.perPositionHeight;
    var perPositionHeightEnabled =
      defined(perPositionHeightProperty) &&
      (perPositionHeightProperty.isConstant
        ? perPositionHeightProperty.getValue(Iso8601.MINIMUM_VALUE)
        : true);
    return onTerrain && !perPositionHeightEnabled;
  };

  PolygonGeometryUpdater.prototype._isDynamic = function (entity, polygon) {
    return (
      !polygon.hierarchy.isConstant || //
      !Property.isConstant(polygon.height) || //
      !Property.isConstant(polygon.extrudedHeight) || //
      !Property.isConstant(polygon.granularity) || //
      !Property.isConstant(polygon.stRotation) || //
      !Property.isConstant(polygon.outlineWidth) || //
      !Property.isConstant(polygon.perPositionHeight) || //
      !Property.isConstant(polygon.closeTop) || //
      !Property.isConstant(polygon.closeBottom) || //
      !Property.isConstant(polygon.zIndex) || //
      !Property.isConstant(polygon.arcType) || //
      (this._onTerrain &&
        !Property.isConstant(this._materialProperty) &&
        !(this._materialProperty instanceof ColorMaterialProperty))
    );
  };

  PolygonGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    polygon
  ) {
    var isColorMaterial = this._materialProperty instanceof ColorMaterialProperty;

    var options = this._options;
    options.vertexFormat = isColorMaterial
      ? PerInstanceColorAppearance.VERTEX_FORMAT
      : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;

    var hierarchyValue = polygon.hierarchy.getValue(Iso8601.MINIMUM_VALUE);
    var heightValue = Property.getValueOrUndefined(
      polygon.height,
      Iso8601.MINIMUM_VALUE
    );
    var heightReferenceValue = Property.getValueOrDefault(
      polygon.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      polygon.extrudedHeight,
      Iso8601.MINIMUM_VALUE
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      polygon.extrudedHeightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var perPositionHeightValue = Property.getValueOrDefault(
      polygon.perPositionHeight,
      Iso8601.MINIMUM_VALUE,
      false
    );

    heightValue = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    var offsetAttribute;
    if (perPositionHeightValue) {
      if (defined(heightValue)) {
        heightValue = undefined;
        oneTimeWarning(heightAndPerPositionHeightWarning);
      }
      if (
        heightReferenceValue !== HeightReference$1.NONE &&
        perPositionHeightValue
      ) {
        heightValue = undefined;
        oneTimeWarning(heightReferenceAndPerPositionHeightWarning);
      }
    } else {
      if (defined(extrudedHeightValue) && !defined(heightValue)) {
        heightValue = 0;
      }
      offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
        heightValue,
        heightReferenceValue,
        extrudedHeightValue,
        extrudedHeightReferenceValue
      );
    }

    options.polygonHierarchy = hierarchyValue;
    options.granularity = Property.getValueOrUndefined(
      polygon.granularity,
      Iso8601.MINIMUM_VALUE
    );
    options.stRotation = Property.getValueOrUndefined(
      polygon.stRotation,
      Iso8601.MINIMUM_VALUE
    );
    options.perPositionHeight = perPositionHeightValue;
    options.closeTop = Property.getValueOrDefault(
      polygon.closeTop,
      Iso8601.MINIMUM_VALUE,
      true
    );
    options.closeBottom = Property.getValueOrDefault(
      polygon.closeBottom,
      Iso8601.MINIMUM_VALUE,
      true
    );
    options.offsetAttribute = offsetAttribute;
    options.height = heightValue;
    options.arcType = Property.getValueOrDefault(
      polygon.arcType,
      Iso8601.MINIMUM_VALUE,
      ArcType$1.GEODESIC
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        PolygonGeometry.computeRectangle(options, scratchRectangle$5)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  PolygonGeometryUpdater.prototype._getIsClosed = function (options) {
    var height = options.height;
    var extrudedHeight = options.extrudedHeight;
    var isExtruded = defined(extrudedHeight) && extrudedHeight !== height;
    return (
      !options.perPositionHeight &&
      ((!isExtruded && height === 0) ||
        (isExtruded && options.closeTop && options.closeBottom))
    );
  };

  PolygonGeometryUpdater.DynamicGeometryUpdater = DyanmicPolygonGeometryUpdater;

  /**
   * @private
   */
  function DyanmicPolygonGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DyanmicPolygonGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DyanmicPolygonGeometryUpdater.prototype.constructor = DyanmicPolygonGeometryUpdater;
  }

  DyanmicPolygonGeometryUpdater.prototype._isHidden = function (
    entity,
    polygon,
    time
  ) {
    return (
      !defined(this._options.polygonHierarchy) ||
      DynamicGeometryUpdater.prototype._isHidden.call(this, entity, polygon, time)
    );
  };

  DyanmicPolygonGeometryUpdater.prototype._setOptions = function (
    entity,
    polygon,
    time
  ) {
    var options = this._options;

    options.polygonHierarchy = Property.getValueOrUndefined(
      polygon.hierarchy,
      time
    );

    var heightValue = Property.getValueOrUndefined(polygon.height, time);
    var heightReferenceValue = Property.getValueOrDefault(
      polygon.heightReference,
      time,
      HeightReference$1.NONE
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      polygon.extrudedHeightReference,
      time,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      polygon.extrudedHeight,
      time
    );
    var perPositionHeightValue = Property.getValueOrUndefined(
      polygon.perPositionHeight,
      time
    );

    heightValue = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      extrudedHeightReferenceValue
    );

    var offsetAttribute;
    if (perPositionHeightValue) {
      if (defined(heightValue)) {
        heightValue = undefined;
        oneTimeWarning(heightAndPerPositionHeightWarning);
      }
      if (
        heightReferenceValue !== HeightReference$1.NONE &&
        perPositionHeightValue
      ) {
        heightValue = undefined;
        oneTimeWarning(heightReferenceAndPerPositionHeightWarning);
      }
    } else {
      if (defined(extrudedHeightValue) && !defined(heightValue)) {
        heightValue = 0;
      }

      offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
        heightValue,
        heightReferenceValue,
        extrudedHeightValue,
        extrudedHeightReferenceValue
      );
    }

    options.granularity = Property.getValueOrUndefined(polygon.granularity, time);
    options.stRotation = Property.getValueOrUndefined(polygon.stRotation, time);
    options.perPositionHeight = Property.getValueOrUndefined(
      polygon.perPositionHeight,
      time
    );
    options.closeTop = Property.getValueOrDefault(polygon.closeTop, time, true);
    options.closeBottom = Property.getValueOrDefault(
      polygon.closeBottom,
      time,
      true
    );
    options.offsetAttribute = offsetAttribute;
    options.height = heightValue;
    options.arcType = Property.getValueOrDefault(
      polygon.arcType,
      time,
      ArcType$1.GEODESIC
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        PolygonGeometry.computeRectangle(options, scratchRectangle$5)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  var scratchColor$f = new Color();

  function PolylineVolumeGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.polylinePositions = undefined;
    this.shapePositions = undefined;
    this.cornerType = undefined;
    this.granularity = undefined;
  }

  /**
   * A {@link GeometryUpdater} for polyline volumes.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias PolylineVolumeGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function PolylineVolumeGeometryUpdater(entity, scene) {
    GeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new PolylineVolumeGeometryOptions(entity),
      geometryPropertyName: "polylineVolume",
      observedPropertyNames: ["availability", "polylineVolume"],
    });

    this._onEntityPropertyChanged(
      entity,
      "polylineVolume",
      entity.polylineVolume,
      undefined
    );
  }

  if (defined(Object.create)) {
    PolylineVolumeGeometryUpdater.prototype = Object.create(
      GeometryUpdater.prototype
    );
    PolylineVolumeGeometryUpdater.prototype.constructor = PolylineVolumeGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  PolylineVolumeGeometryUpdater.prototype.createFillGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var attributes;

    var color;
    var show = new ShowGeometryInstanceAttribute(
      isAvailable &&
        entity.isShowing &&
        this._showProperty.getValue(time) &&
        this._fillProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );
    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$f);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      color = ColorGeometryInstanceAttribute.fromColor(currentColor);
      attributes = {
        show: show,
        distanceDisplayCondition: distanceDisplayConditionAttribute,
        color: color,
      };
    } else {
      attributes = {
        show: show,
        distanceDisplayCondition: distanceDisplayConditionAttribute,
      };
    }

    return new GeometryInstance({
      id: entity,
      geometry: new PolylineVolumeGeometry(this._options),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  PolylineVolumeGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$f
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    return new GeometryInstance({
      id: entity,
      geometry: new PolylineVolumeOutlineGeometry(this._options),
      attributes: {
        show: new ShowGeometryInstanceAttribute(
          isAvailable &&
            entity.isShowing &&
            this._showProperty.getValue(time) &&
            this._showOutlineProperty.getValue(time)
        ),
        color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
        distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
          distanceDisplayCondition
        ),
      },
    });
  };

  PolylineVolumeGeometryUpdater.prototype._isHidden = function (
    entity,
    polylineVolume
  ) {
    return (
      !defined(polylineVolume.positions) ||
      !defined(polylineVolume.shape) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, polylineVolume)
    );
  };

  PolylineVolumeGeometryUpdater.prototype._isDynamic = function (
    entity,
    polylineVolume
  ) {
    return (
      !polylineVolume.positions.isConstant || //
      !polylineVolume.shape.isConstant || //
      !Property.isConstant(polylineVolume.granularity) || //
      !Property.isConstant(polylineVolume.outlineWidth) || //
      !Property.isConstant(polylineVolume.cornerType)
    );
  };

  PolylineVolumeGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    polylineVolume
  ) {
    var granularity = polylineVolume.granularity;
    var cornerType = polylineVolume.cornerType;

    var options = this._options;
    var isColorMaterial = this._materialProperty instanceof ColorMaterialProperty;
    options.vertexFormat = isColorMaterial
      ? PerInstanceColorAppearance.VERTEX_FORMAT
      : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.polylinePositions = polylineVolume.positions.getValue(
      Iso8601.MINIMUM_VALUE,
      options.polylinePositions
    );
    options.shapePositions = polylineVolume.shape.getValue(
      Iso8601.MINIMUM_VALUE,
      options.shape
    );
    options.granularity = defined(granularity)
      ? granularity.getValue(Iso8601.MINIMUM_VALUE)
      : undefined;
    options.cornerType = defined(cornerType)
      ? cornerType.getValue(Iso8601.MINIMUM_VALUE)
      : undefined;
  };

  PolylineVolumeGeometryUpdater.DynamicGeometryUpdater = DynamicPolylineVolumeGeometryUpdater;

  /**
   * @private
   */
  function DynamicPolylineVolumeGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicPolylineVolumeGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicPolylineVolumeGeometryUpdater.prototype.constructor = DynamicPolylineVolumeGeometryUpdater;
  }

  DynamicPolylineVolumeGeometryUpdater.prototype._isHidden = function (
    entity,
    polylineVolume,
    time
  ) {
    var options = this._options;
    return (
      !defined(options.polylinePositions) ||
      !defined(options.shapePositions) ||
      DynamicGeometryUpdater.prototype._isHidden.call(
        this,
        entity,
        polylineVolume,
        time
      )
    );
  };

  DynamicPolylineVolumeGeometryUpdater.prototype._setOptions = function (
    entity,
    polylineVolume,
    time
  ) {
    var options = this._options;
    options.polylinePositions = Property.getValueOrUndefined(
      polylineVolume.positions,
      time,
      options.polylinePositions
    );
    options.shapePositions = Property.getValueOrUndefined(
      polylineVolume.shape,
      time
    );
    options.granularity = Property.getValueOrUndefined(
      polylineVolume.granularity,
      time
    );
    options.cornerType = Property.getValueOrUndefined(
      polylineVolume.cornerType,
      time
    );
  };

  var scratchColor$g = new Color();
  var defaultOffset$7 = Cartesian3.ZERO;
  var offsetScratch$9 = new Cartesian3();
  var scratchRectangle$6 = new Rectangle();
  var scratchCenterRect = new Rectangle();
  var scratchCarto$1 = new Cartographic();

  function RectangleGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.rectangle = undefined;
    this.height = undefined;
    this.extrudedHeight = undefined;
    this.granularity = undefined;
    this.stRotation = undefined;
    this.rotation = undefined;
    this.offsetAttribute = undefined;
  }

  /**
   * A {@link GeometryUpdater} for rectangles.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias RectangleGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function RectangleGeometryUpdater(entity, scene) {
    GroundGeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new RectangleGeometryOptions(entity),
      geometryPropertyName: "rectangle",
      observedPropertyNames: ["availability", "rectangle"],
    });

    this._onEntityPropertyChanged(
      entity,
      "rectangle",
      entity.rectangle,
      undefined
    );
  }

  if (defined(Object.create)) {
    RectangleGeometryUpdater.prototype = Object.create(
      GroundGeometryUpdater.prototype
    );
    RectangleGeometryUpdater.prototype.constructor = RectangleGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  RectangleGeometryUpdater.prototype.createFillGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._fillProperty.getValue(time)
      ),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        this._distanceDisplayConditionProperty.getValue(time)
      ),
      offset: undefined,
      color: undefined,
    };

    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$g);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }
    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$7,
          offsetScratch$9
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new RectangleGeometry(this._options),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  RectangleGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$g
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    var attributes = {
      show: new ShowGeometryInstanceAttribute(
        isAvailable &&
          entity.isShowing &&
          this._showProperty.getValue(time) &&
          this._showOutlineProperty.getValue(time)
      ),
      color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
      distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
        distanceDisplayCondition
      ),
      offset: undefined,
    };

    if (defined(this._options.offsetAttribute)) {
      attributes.offset = OffsetGeometryInstanceAttribute.fromCartesian3(
        Property.getValueOrDefault(
          this._terrainOffsetProperty,
          time,
          defaultOffset$7,
          offsetScratch$9
        )
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new RectangleOutlineGeometry(this._options),
      attributes: attributes,
    });
  };

  RectangleGeometryUpdater.prototype._computeCenter = function (time, result) {
    var rect = Property.getValueOrUndefined(
      this._entity.rectangle.coordinates,
      time,
      scratchCenterRect
    );
    if (!defined(rect)) {
      return;
    }
    var center = Rectangle.center(rect, scratchCarto$1);
    return Cartographic.toCartesian(center, Ellipsoid.WGS84, result);
  };

  RectangleGeometryUpdater.prototype._isHidden = function (entity, rectangle) {
    return (
      !defined(rectangle.coordinates) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, rectangle)
    );
  };

  RectangleGeometryUpdater.prototype._isDynamic = function (entity, rectangle) {
    return (
      !rectangle.coordinates.isConstant || //
      !Property.isConstant(rectangle.height) || //
      !Property.isConstant(rectangle.extrudedHeight) || //
      !Property.isConstant(rectangle.granularity) || //
      !Property.isConstant(rectangle.stRotation) || //
      !Property.isConstant(rectangle.rotation) || //
      !Property.isConstant(rectangle.outlineWidth) || //
      !Property.isConstant(rectangle.zIndex) || //
      (this._onTerrain &&
        !Property.isConstant(this._materialProperty) &&
        !(this._materialProperty instanceof ColorMaterialProperty))
    );
  };

  RectangleGeometryUpdater.prototype._setStaticOptions = function (
    entity,
    rectangle
  ) {
    var isColorMaterial = this._materialProperty instanceof ColorMaterialProperty;

    var heightValue = Property.getValueOrUndefined(
      rectangle.height,
      Iso8601.MINIMUM_VALUE
    );
    var heightReferenceValue = Property.getValueOrDefault(
      rectangle.heightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      rectangle.extrudedHeight,
      Iso8601.MINIMUM_VALUE
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      rectangle.extrudedHeightReference,
      Iso8601.MINIMUM_VALUE,
      HeightReference$1.NONE
    );
    if (defined(extrudedHeightValue) && !defined(heightValue)) {
      heightValue = 0;
    }

    var options = this._options;
    options.vertexFormat = isColorMaterial
      ? PerInstanceColorAppearance.VERTEX_FORMAT
      : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.rectangle = rectangle.coordinates.getValue(
      Iso8601.MINIMUM_VALUE,
      options.rectangle
    );
    options.granularity = Property.getValueOrUndefined(
      rectangle.granularity,
      Iso8601.MINIMUM_VALUE
    );
    options.stRotation = Property.getValueOrUndefined(
      rectangle.stRotation,
      Iso8601.MINIMUM_VALUE
    );
    options.rotation = Property.getValueOrUndefined(
      rectangle.rotation,
      Iso8601.MINIMUM_VALUE
    );
    options.offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
      heightValue,
      heightReferenceValue,
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    options.height = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        RectangleGeometry.computeRectangle(options, scratchRectangle$6)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  RectangleGeometryUpdater.DynamicGeometryUpdater = DynamicRectangleGeometryUpdater;

  /**
   * @private
   */
  function DynamicRectangleGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicRectangleGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicRectangleGeometryUpdater.prototype.constructor = DynamicRectangleGeometryUpdater;
  }

  DynamicRectangleGeometryUpdater.prototype._isHidden = function (
    entity,
    rectangle,
    time
  ) {
    return (
      !defined(this._options.rectangle) ||
      DynamicGeometryUpdater.prototype._isHidden.call(
        this,
        entity,
        rectangle,
        time
      )
    );
  };

  DynamicRectangleGeometryUpdater.prototype._setOptions = function (
    entity,
    rectangle,
    time
  ) {
    var options = this._options;
    var heightValue = Property.getValueOrUndefined(rectangle.height, time);
    var heightReferenceValue = Property.getValueOrDefault(
      rectangle.heightReference,
      time,
      HeightReference$1.NONE
    );
    var extrudedHeightValue = Property.getValueOrUndefined(
      rectangle.extrudedHeight,
      time
    );
    var extrudedHeightReferenceValue = Property.getValueOrDefault(
      rectangle.extrudedHeightReference,
      time,
      HeightReference$1.NONE
    );
    if (defined(extrudedHeightValue) && !defined(heightValue)) {
      heightValue = 0;
    }

    options.rectangle = Property.getValueOrUndefined(
      rectangle.coordinates,
      time,
      options.rectangle
    );
    options.granularity = Property.getValueOrUndefined(
      rectangle.granularity,
      time
    );
    options.stRotation = Property.getValueOrUndefined(rectangle.stRotation, time);
    options.rotation = Property.getValueOrUndefined(rectangle.rotation, time);
    options.offsetAttribute = GroundGeometryUpdater.computeGeometryOffsetAttribute(
      heightValue,
      heightReferenceValue,
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    options.height = GroundGeometryUpdater.getGeometryHeight(
      heightValue,
      heightReferenceValue
    );

    extrudedHeightValue = GroundGeometryUpdater.getGeometryExtrudedHeight(
      extrudedHeightValue,
      extrudedHeightReferenceValue
    );
    if (extrudedHeightValue === GroundGeometryUpdater.CLAMP_TO_GROUND) {
      extrudedHeightValue = ApproximateTerrainHeights.getMinimumMaximumHeights(
        RectangleGeometry.computeRectangle(options, scratchRectangle$6)
      ).minimumTerrainHeight;
    }

    options.extrudedHeight = extrudedHeightValue;
  };

  var colorScratch$2 = new Color();
  var distanceDisplayConditionScratch$1 = new DistanceDisplayCondition();
  var defaultDistanceDisplayCondition$1 = new DistanceDisplayCondition();
  var defaultOffset$8 = Cartesian3.ZERO;
  var offsetScratch$a = new Cartesian3();

  function Batch(
    primitives,
    translucent,
    appearanceType,
    depthFailAppearanceType,
    depthFailMaterialProperty,
    closed,
    shadows
  ) {
    this.translucent = translucent;
    this.appearanceType = appearanceType;
    this.depthFailAppearanceType = depthFailAppearanceType;
    this.depthFailMaterialProperty = depthFailMaterialProperty;
    this.depthFailMaterial = undefined;
    this.closed = closed;
    this.shadows = shadows;
    this.primitives = primitives;
    this.createPrimitive = false;
    this.waitingOnCreate = false;
    this.primitive = undefined;
    this.oldPrimitive = undefined;
    this.geometry = new AssociativeArray();
    this.updaters = new AssociativeArray();
    this.updatersWithAttributes = new AssociativeArray();
    this.attributes = new AssociativeArray();
    this.subscriptions = new AssociativeArray();
    this.showsUpdated = new AssociativeArray();
    this.itemsToRemove = [];
    this.invalidated = false;

    var removeMaterialSubscription;
    if (defined(depthFailMaterialProperty)) {
      removeMaterialSubscription = depthFailMaterialProperty.definitionChanged.addEventListener(
        Batch.prototype.onMaterialChanged,
        this
      );
    }
    this.removeMaterialSubscription = removeMaterialSubscription;
  }

  Batch.prototype.onMaterialChanged = function () {
    this.invalidated = true;
  };

  Batch.prototype.isMaterial = function (updater) {
    var material = this.depthFailMaterialProperty;
    var updaterMaterial = updater.depthFailMaterialProperty;
    if (updaterMaterial === material) {
      return true;
    }
    if (defined(material)) {
      return material.equals(updaterMaterial);
    }
    return false;
  };

  Batch.prototype.add = function (updater, instance) {
    var id = updater.id;
    this.createPrimitive = true;
    this.geometry.set(id, instance);
    this.updaters.set(id, updater);
    if (
      !updater.hasConstantFill ||
      !updater.fillMaterialProperty.isConstant ||
      !Property.isConstant(updater.distanceDisplayConditionProperty) ||
      !Property.isConstant(updater.terrainOffsetProperty)
    ) {
      this.updatersWithAttributes.set(id, updater);
    } else {
      var that = this;
      this.subscriptions.set(
        id,
        updater.entity.definitionChanged.addEventListener(function (
          entity,
          propertyName,
          newValue,
          oldValue
        ) {
          if (propertyName === "isShowing") {
            that.showsUpdated.set(updater.id, updater);
          }
        })
      );
    }
  };

  Batch.prototype.remove = function (updater) {
    var id = updater.id;
    this.createPrimitive = this.geometry.remove(id) || this.createPrimitive;
    if (this.updaters.remove(id)) {
      this.updatersWithAttributes.remove(id);
      var unsubscribe = this.subscriptions.get(id);
      if (defined(unsubscribe)) {
        unsubscribe();
        this.subscriptions.remove(id);
        this.showsUpdated.remove(id);
      }
      return true;
    }
    return false;
  };

  Batch.prototype.update = function (time) {
    var isUpdated = true;
    var removedCount = 0;
    var primitive = this.primitive;
    var primitives = this.primitives;
    var i;

    if (this.createPrimitive) {
      var geometries = this.geometry.values;
      var geometriesLength = geometries.length;
      if (geometriesLength > 0) {
        if (defined(primitive)) {
          if (!defined(this.oldPrimitive)) {
            this.oldPrimitive = primitive;
          } else {
            primitives.remove(primitive);
          }
        }

        var depthFailAppearance;
        if (defined(this.depthFailAppearanceType)) {
          if (defined(this.depthFailMaterialProperty)) {
            this.depthFailMaterial = MaterialProperty.getValue(
              time,
              this.depthFailMaterialProperty,
              this.depthFailMaterial
            );
          }
          depthFailAppearance = new this.depthFailAppearanceType({
            material: this.depthFailMaterial,
            translucent: this.translucent,
            closed: this.closed,
          });
        }

        primitive = new Primitive({
          show: false,
          asynchronous: true,
          geometryInstances: geometries.slice(),
          appearance: new this.appearanceType({
            translucent: this.translucent,
            closed: this.closed,
          }),
          depthFailAppearance: depthFailAppearance,
          shadows: this.shadows,
        });
        primitives.add(primitive);
        isUpdated = false;
      } else {
        if (defined(primitive)) {
          primitives.remove(primitive);
          primitive = undefined;
        }
        var oldPrimitive = this.oldPrimitive;
        if (defined(oldPrimitive)) {
          primitives.remove(oldPrimitive);
          this.oldPrimitive = undefined;
        }
      }

      this.attributes.removeAll();
      this.primitive = primitive;
      this.createPrimitive = false;
      this.waitingOnCreate = true;
    } else if (defined(primitive) && primitive.ready) {
      primitive.show = true;
      if (defined(this.oldPrimitive)) {
        primitives.remove(this.oldPrimitive);
        this.oldPrimitive = undefined;
      }

      if (
        defined(this.depthFailAppearanceType) &&
        !(this.depthFailMaterialProperty instanceof ColorMaterialProperty)
      ) {
        this.depthFailMaterial = MaterialProperty.getValue(
          time,
          this.depthFailMaterialProperty,
          this.depthFailMaterial
        );
        this.primitive.depthFailAppearance.material = this.depthFailMaterial;
      }

      var updatersWithAttributes = this.updatersWithAttributes.values;
      var length = updatersWithAttributes.length;
      var waitingOnCreate = this.waitingOnCreate;
      for (i = 0; i < length; i++) {
        var updater = updatersWithAttributes[i];
        var instance = this.geometry.get(updater.id);

        var attributes = this.attributes.get(instance.id.id);
        if (!defined(attributes)) {
          attributes = primitive.getGeometryInstanceAttributes(instance.id);
          this.attributes.set(instance.id.id, attributes);
        }

        if (!updater.fillMaterialProperty.isConstant || waitingOnCreate) {
          var colorProperty = updater.fillMaterialProperty.color;
          var resultColor = Property.getValueOrDefault(
            colorProperty,
            time,
            Color.WHITE,
            colorScratch$2
          );
          if (!Color.equals(attributes._lastColor, resultColor)) {
            attributes._lastColor = Color.clone(
              resultColor,
              attributes._lastColor
            );
            attributes.color = ColorGeometryInstanceAttribute.toValue(
              resultColor,
              attributes.color
            );
            if (
              (this.translucent && attributes.color[3] === 255) ||
              (!this.translucent && attributes.color[3] !== 255)
            ) {
              this.itemsToRemove[removedCount++] = updater;
            }
          }
        }

        if (
          defined(this.depthFailAppearanceType) &&
          updater.depthFailMaterialProperty instanceof ColorMaterialProperty &&
          (!updater.depthFailMaterialProperty.isConstant || waitingOnCreate)
        ) {
          var depthFailColorProperty = updater.depthFailMaterialProperty.color;
          var depthColor = Property.getValueOrDefault(
            depthFailColorProperty,
            time,
            Color.WHITE,
            colorScratch$2
          );
          if (!Color.equals(attributes._lastDepthFailColor, depthColor)) {
            attributes._lastDepthFailColor = Color.clone(
              depthColor,
              attributes._lastDepthFailColor
            );
            attributes.depthFailColor = ColorGeometryInstanceAttribute.toValue(
              depthColor,
              attributes.depthFailColor
            );
          }
        }

        var show =
          updater.entity.isShowing &&
          (updater.hasConstantFill || updater.isFilled(time));
        var currentShow = attributes.show[0] === 1;
        if (show !== currentShow) {
          attributes.show = ShowGeometryInstanceAttribute.toValue(
            show,
            attributes.show
          );
        }

        var distanceDisplayConditionProperty =
          updater.distanceDisplayConditionProperty;
        if (!Property.isConstant(distanceDisplayConditionProperty)) {
          var distanceDisplayCondition = Property.getValueOrDefault(
            distanceDisplayConditionProperty,
            time,
            defaultDistanceDisplayCondition$1,
            distanceDisplayConditionScratch$1
          );
          if (
            !DistanceDisplayCondition.equals(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            )
          ) {
            attributes._lastDistanceDisplayCondition = DistanceDisplayCondition.clone(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            );
            attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
              distanceDisplayCondition,
              attributes.distanceDisplayCondition
            );
          }
        }

        var offsetProperty = updater.terrainOffsetProperty;
        if (!Property.isConstant(offsetProperty)) {
          var offset = Property.getValueOrDefault(
            offsetProperty,
            time,
            defaultOffset$8,
            offsetScratch$a
          );
          if (!Cartesian3.equals(offset, attributes._lastOffset)) {
            attributes._lastOffset = Cartesian3.clone(
              offset,
              attributes._lastOffset
            );
            attributes.offset = OffsetGeometryInstanceAttribute.toValue(
              offset,
              attributes.offset
            );
          }
        }
      }

      this.updateShows(primitive);
      this.waitingOnCreate = false;
    } else if (defined(primitive) && !primitive.ready) {
      isUpdated = false;
    }
    this.itemsToRemove.length = removedCount;
    return isUpdated;
  };

  Batch.prototype.updateShows = function (primitive) {
    var showsUpdated = this.showsUpdated.values;
    var length = showsUpdated.length;
    for (var i = 0; i < length; i++) {
      var updater = showsUpdated[i];
      var instance = this.geometry.get(updater.id);

      var attributes = this.attributes.get(instance.id.id);
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(instance.id);
        this.attributes.set(instance.id.id, attributes);
      }

      var show = updater.entity.isShowing;
      var currentShow = attributes.show[0] === 1;
      if (show !== currentShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          show,
          attributes.show
        );
        instance.attributes.show.value[0] = attributes.show[0];
      }
    }
    this.showsUpdated.removeAll();
  };

  Batch.prototype.contains = function (updater) {
    return this.updaters.contains(updater.id);
  };

  Batch.prototype.getBoundingSphere = function (updater, result) {
    var primitive = this.primitive;
    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }
    var attributes = primitive.getGeometryInstanceAttributes(updater.entity);
    if (
      !defined(attributes) ||
      !defined(attributes.boundingSphere) || //
      (defined(attributes.show) && attributes.show[0] === 0)
    ) {
      return BoundingSphereState$1.FAILED;
    }
    attributes.boundingSphere.clone(result);
    return BoundingSphereState$1.DONE;
  };

  Batch.prototype.destroy = function () {
    var primitive = this.primitive;
    var primitives = this.primitives;
    if (defined(primitive)) {
      primitives.remove(primitive);
    }
    var oldPrimitive = this.oldPrimitive;
    if (defined(oldPrimitive)) {
      primitives.remove(oldPrimitive);
    }
    if (defined(this.removeMaterialSubscription)) {
      this.removeMaterialSubscription();
    }
  };

  /**
   * @private
   */
  function StaticGeometryColorBatch(
    primitives,
    appearanceType,
    depthFailAppearanceType,
    closed,
    shadows
  ) {
    this._solidItems = [];
    this._translucentItems = [];
    this._primitives = primitives;
    this._appearanceType = appearanceType;
    this._depthFailAppearanceType = depthFailAppearanceType;
    this._closed = closed;
    this._shadows = shadows;
  }

  StaticGeometryColorBatch.prototype.add = function (time, updater) {
    var items;
    var translucent;
    var instance = updater.createFillGeometryInstance(time);
    if (instance.attributes.color.value[3] === 255) {
      items = this._solidItems;
      translucent = false;
    } else {
      items = this._translucentItems;
      translucent = true;
    }

    var length = items.length;
    for (var i = 0; i < length; i++) {
      var item = items[i];
      if (item.isMaterial(updater)) {
        item.add(updater, instance);
        return;
      }
    }
    var batch = new Batch(
      this._primitives,
      translucent,
      this._appearanceType,
      this._depthFailAppearanceType,
      updater.depthFailMaterialProperty,
      this._closed,
      this._shadows
    );
    batch.add(updater, instance);
    items.push(batch);
  };

  function removeItem(items, updater) {
    var length = items.length;
    for (var i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.remove(updater)) {
        if (item.updaters.length === 0) {
          items.splice(i, 1);
          item.destroy();
        }
        return true;
      }
    }
    return false;
  }

  StaticGeometryColorBatch.prototype.remove = function (updater) {
    if (!removeItem(this._solidItems, updater)) {
      removeItem(this._translucentItems, updater);
    }
  };

  function moveItems(batch, items, time) {
    var itemsMoved = false;
    var length = items.length;
    for (var i = 0; i < length; ++i) {
      var item = items[i];
      var itemsToRemove = item.itemsToRemove;
      var itemsToMoveLength = itemsToRemove.length;
      if (itemsToMoveLength > 0) {
        for (i = 0; i < itemsToMoveLength; i++) {
          var updater = itemsToRemove[i];
          item.remove(updater);
          batch.add(time, updater);
          itemsMoved = true;
        }
      }
    }
    return itemsMoved;
  }

  function updateItems(batch, items, time, isUpdated) {
    var length = items.length;
    var i;
    for (i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.invalidated) {
        items.splice(i, 1);
        var updaters = item.updaters.values;
        var updatersLength = updaters.length;
        for (var h = 0; h < updatersLength; h++) {
          batch.add(time, updaters[h]);
        }
        item.destroy();
      }
    }

    length = items.length;
    for (i = 0; i < length; ++i) {
      isUpdated = items[i].update(time) && isUpdated;
    }
    return isUpdated;
  }

  StaticGeometryColorBatch.prototype.update = function (time) {
    //Perform initial update
    var isUpdated = updateItems(this, this._solidItems, time, true);
    isUpdated =
      updateItems(this, this._translucentItems, time, isUpdated) && isUpdated;

    //If any items swapped between solid/translucent, we need to
    //move them between batches
    var solidsMoved = moveItems(this, this._solidItems, time);
    var translucentsMoved = moveItems(this, this._translucentItems, time);

    //If we moved anything around, we need to re-build the primitive
    if (solidsMoved || translucentsMoved) {
      isUpdated =
        updateItems(this, this._solidItems, time, isUpdated) && isUpdated;
      isUpdated =
        updateItems(this, this._translucentItems, time, isUpdated) && isUpdated;
    }

    return isUpdated;
  };

  function getBoundingSphere(items, updater, result) {
    var length = items.length;
    for (var i = 0; i < length; i++) {
      var item = items[i];
      if (item.contains(updater)) {
        return item.getBoundingSphere(updater, result);
      }
    }
    return BoundingSphereState$1.FAILED;
  }

  StaticGeometryColorBatch.prototype.getBoundingSphere = function (
    updater,
    result
  ) {
    var boundingSphere = getBoundingSphere(this._solidItems, updater, result);
    if (boundingSphere === BoundingSphereState$1.FAILED) {
      return getBoundingSphere(this._translucentItems, updater, result);
    }
    return boundingSphere;
  };

  function removeAllPrimitives(items) {
    var length = items.length;
    for (var i = 0; i < length; i++) {
      items[i].destroy();
    }
    items.length = 0;
  }

  StaticGeometryColorBatch.prototype.removeAllPrimitives = function () {
    removeAllPrimitives(this._solidItems);
    removeAllPrimitives(this._translucentItems);
  };

  var distanceDisplayConditionScratch$2 = new DistanceDisplayCondition();
  var defaultDistanceDisplayCondition$2 = new DistanceDisplayCondition();
  var defaultOffset$9 = Cartesian3.ZERO;
  var offsetScratch$b = new Cartesian3();

  function Batch$1(
    primitives,
    appearanceType,
    materialProperty,
    depthFailAppearanceType,
    depthFailMaterialProperty,
    closed,
    shadows
  ) {
    this.primitives = primitives;
    this.appearanceType = appearanceType;
    this.materialProperty = materialProperty;
    this.depthFailAppearanceType = depthFailAppearanceType;
    this.depthFailMaterialProperty = depthFailMaterialProperty;
    this.closed = closed;
    this.shadows = shadows;
    this.updaters = new AssociativeArray();
    this.createPrimitive = true;
    this.primitive = undefined;
    this.oldPrimitive = undefined;
    this.geometry = new AssociativeArray();
    this.material = undefined;
    this.depthFailMaterial = undefined;
    this.updatersWithAttributes = new AssociativeArray();
    this.attributes = new AssociativeArray();
    this.invalidated = false;
    this.removeMaterialSubscription = materialProperty.definitionChanged.addEventListener(
      Batch$1.prototype.onMaterialChanged,
      this
    );
    this.subscriptions = new AssociativeArray();
    this.showsUpdated = new AssociativeArray();
  }

  Batch$1.prototype.onMaterialChanged = function () {
    this.invalidated = true;
  };

  Batch$1.prototype.isMaterial = function (updater) {
    var material = this.materialProperty;
    var updaterMaterial = updater.fillMaterialProperty;
    var depthFailMaterial = this.depthFailMaterialProperty;
    var updaterDepthFailMaterial = updater.depthFailMaterialProperty;

    if (
      updaterMaterial === material &&
      updaterDepthFailMaterial === depthFailMaterial
    ) {
      return true;
    }
    var equals = defined(material) && material.equals(updaterMaterial);
    equals =
      ((!defined(depthFailMaterial) && !defined(updaterDepthFailMaterial)) ||
        (defined(depthFailMaterial) &&
          depthFailMaterial.equals(updaterDepthFailMaterial))) &&
      equals;
    return equals;
  };

  Batch$1.prototype.add = function (time, updater) {
    var id = updater.id;
    this.updaters.set(id, updater);
    this.geometry.set(id, updater.createFillGeometryInstance(time));
    if (
      !updater.hasConstantFill ||
      !updater.fillMaterialProperty.isConstant ||
      !Property.isConstant(updater.distanceDisplayConditionProperty) ||
      !Property.isConstant(updater.terrainOffsetProperty)
    ) {
      this.updatersWithAttributes.set(id, updater);
    } else {
      var that = this;
      this.subscriptions.set(
        id,
        updater.entity.definitionChanged.addEventListener(function (
          entity,
          propertyName,
          newValue,
          oldValue
        ) {
          if (propertyName === "isShowing") {
            that.showsUpdated.set(updater.id, updater);
          }
        })
      );
    }
    this.createPrimitive = true;
  };

  Batch$1.prototype.remove = function (updater) {
    var id = updater.id;
    this.createPrimitive = this.geometry.remove(id) || this.createPrimitive;
    if (this.updaters.remove(id)) {
      this.updatersWithAttributes.remove(id);
      var unsubscribe = this.subscriptions.get(id);
      if (defined(unsubscribe)) {
        unsubscribe();
        this.subscriptions.remove(id);
        this.showsUpdated.remove(id);
      }
      return true;
    }
    return false;
  };

  var colorScratch$3 = new Color();

  Batch$1.prototype.update = function (time) {
    var isUpdated = true;
    var primitive = this.primitive;
    var primitives = this.primitives;
    var geometries = this.geometry.values;
    var i;

    if (this.createPrimitive) {
      var geometriesLength = geometries.length;
      if (geometriesLength > 0) {
        if (defined(primitive)) {
          if (!defined(this.oldPrimitive)) {
            this.oldPrimitive = primitive;
          } else {
            primitives.remove(primitive);
          }
        }

        this.material = MaterialProperty.getValue(
          time,
          this.materialProperty,
          this.material
        );

        var depthFailAppearance;
        if (defined(this.depthFailMaterialProperty)) {
          this.depthFailMaterial = MaterialProperty.getValue(
            time,
            this.depthFailMaterialProperty,
            this.depthFailMaterial
          );
          depthFailAppearance = new this.depthFailAppearanceType({
            material: this.depthFailMaterial,
            translucent: this.depthFailMaterial.isTranslucent(),
            closed: this.closed,
          });
        }

        primitive = new Primitive({
          show: false,
          asynchronous: true,
          geometryInstances: geometries.slice(),
          appearance: new this.appearanceType({
            material: this.material,
            translucent: this.material.isTranslucent(),
            closed: this.closed,
          }),
          depthFailAppearance: depthFailAppearance,
          shadows: this.shadows,
        });

        primitives.add(primitive);
        isUpdated = false;
      } else {
        if (defined(primitive)) {
          primitives.remove(primitive);
          primitive = undefined;
        }
        var oldPrimitive = this.oldPrimitive;
        if (defined(oldPrimitive)) {
          primitives.remove(oldPrimitive);
          this.oldPrimitive = undefined;
        }
      }

      this.attributes.removeAll();
      this.primitive = primitive;
      this.createPrimitive = false;
    } else if (defined(primitive) && primitive.ready) {
      primitive.show = true;
      if (defined(this.oldPrimitive)) {
        primitives.remove(this.oldPrimitive);
        this.oldPrimitive = undefined;
      }

      this.material = MaterialProperty.getValue(
        time,
        this.materialProperty,
        this.material
      );
      this.primitive.appearance.material = this.material;

      if (
        defined(this.depthFailAppearanceType) &&
        !(this.depthFailMaterialProperty instanceof ColorMaterialProperty)
      ) {
        this.depthFailMaterial = MaterialProperty.getValue(
          time,
          this.depthFailMaterialProperty,
          this.depthFailMaterial
        );
        this.primitive.depthFailAppearance.material = this.depthFailMaterial;
      }

      var updatersWithAttributes = this.updatersWithAttributes.values;
      var length = updatersWithAttributes.length;
      for (i = 0; i < length; i++) {
        var updater = updatersWithAttributes[i];
        var entity = updater.entity;
        var instance = this.geometry.get(updater.id);

        var attributes = this.attributes.get(instance.id.id);
        if (!defined(attributes)) {
          attributes = primitive.getGeometryInstanceAttributes(instance.id);
          this.attributes.set(instance.id.id, attributes);
        }

        if (
          defined(this.depthFailAppearanceType) &&
          this.depthFailMaterialProperty instanceof ColorMaterialProperty &&
          !updater.depthFailMaterialProperty.isConstant
        ) {
          var depthFailColorProperty = updater.depthFailMaterialProperty.color;
          var depthFailColor = Property.getValueOrDefault(
            depthFailColorProperty,
            time,
            Color.WHITE,
            colorScratch$3
          );
          if (!Color.equals(attributes._lastDepthFailColor, depthFailColor)) {
            attributes._lastDepthFailColor = Color.clone(
              depthFailColor,
              attributes._lastDepthFailColor
            );
            attributes.depthFailColor = ColorGeometryInstanceAttribute.toValue(
              depthFailColor,
              attributes.depthFailColor
            );
          }
        }

        var show =
          entity.isShowing && (updater.hasConstantFill || updater.isFilled(time));
        var currentShow = attributes.show[0] === 1;
        if (show !== currentShow) {
          attributes.show = ShowGeometryInstanceAttribute.toValue(
            show,
            attributes.show
          );
        }

        var distanceDisplayConditionProperty =
          updater.distanceDisplayConditionProperty;
        if (!Property.isConstant(distanceDisplayConditionProperty)) {
          var distanceDisplayCondition = Property.getValueOrDefault(
            distanceDisplayConditionProperty,
            time,
            defaultDistanceDisplayCondition$2,
            distanceDisplayConditionScratch$2
          );
          if (
            !DistanceDisplayCondition.equals(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            )
          ) {
            attributes._lastDistanceDisplayCondition = DistanceDisplayCondition.clone(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            );
            attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
              distanceDisplayCondition,
              attributes.distanceDisplayCondition
            );
          }
        }

        var offsetProperty = updater.terrainOffsetProperty;
        if (!Property.isConstant(offsetProperty)) {
          var offset = Property.getValueOrDefault(
            offsetProperty,
            time,
            defaultOffset$9,
            offsetScratch$b
          );
          if (!Cartesian3.equals(offset, attributes._lastOffset)) {
            attributes._lastOffset = Cartesian3.clone(
              offset,
              attributes._lastOffset
            );
            attributes.offset = OffsetGeometryInstanceAttribute.toValue(
              offset,
              attributes.offset
            );
          }
        }
      }

      this.updateShows(primitive);
    } else if (defined(primitive) && !primitive.ready) {
      isUpdated = false;
    }
    return isUpdated;
  };

  Batch$1.prototype.updateShows = function (primitive) {
    var showsUpdated = this.showsUpdated.values;
    var length = showsUpdated.length;
    for (var i = 0; i < length; i++) {
      var updater = showsUpdated[i];
      var entity = updater.entity;
      var instance = this.geometry.get(updater.id);

      var attributes = this.attributes.get(instance.id.id);
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(instance.id);
        this.attributes.set(instance.id.id, attributes);
      }

      var show = entity.isShowing;
      var currentShow = attributes.show[0] === 1;
      if (show !== currentShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          show,
          attributes.show
        );
        instance.attributes.show.value[0] = attributes.show[0];
      }
    }
    this.showsUpdated.removeAll();
  };

  Batch$1.prototype.contains = function (updater) {
    return this.updaters.contains(updater.id);
  };

  Batch$1.prototype.getBoundingSphere = function (updater, result) {
    var primitive = this.primitive;
    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }
    var attributes = primitive.getGeometryInstanceAttributes(updater.entity);
    if (
      !defined(attributes) ||
      !defined(attributes.boundingSphere) ||
      (defined(attributes.show) && attributes.show[0] === 0)
    ) {
      return BoundingSphereState$1.FAILED;
    }
    attributes.boundingSphere.clone(result);
    return BoundingSphereState$1.DONE;
  };

  Batch$1.prototype.destroy = function () {
    var primitive = this.primitive;
    var primitives = this.primitives;
    if (defined(primitive)) {
      primitives.remove(primitive);
    }
    var oldPrimitive = this.oldPrimitive;
    if (defined(oldPrimitive)) {
      primitives.remove(oldPrimitive);
    }
    this.removeMaterialSubscription();
  };

  /**
   * @private
   */
  function StaticGeometryPerMaterialBatch(
    primitives,
    appearanceType,
    depthFailAppearanceType,
    closed,
    shadows
  ) {
    this._items = [];
    this._primitives = primitives;
    this._appearanceType = appearanceType;
    this._depthFailAppearanceType = depthFailAppearanceType;
    this._closed = closed;
    this._shadows = shadows;
  }

  StaticGeometryPerMaterialBatch.prototype.add = function (time, updater) {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      var item = items[i];
      if (item.isMaterial(updater)) {
        item.add(time, updater);
        return;
      }
    }
    var batch = new Batch$1(
      this._primitives,
      this._appearanceType,
      updater.fillMaterialProperty,
      this._depthFailAppearanceType,
      updater.depthFailMaterialProperty,
      this._closed,
      this._shadows
    );
    batch.add(time, updater);
    items.push(batch);
  };

  StaticGeometryPerMaterialBatch.prototype.remove = function (updater) {
    var items = this._items;
    var length = items.length;
    for (var i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.remove(updater)) {
        if (item.updaters.length === 0) {
          items.splice(i, 1);
          item.destroy();
        }
        break;
      }
    }
  };

  StaticGeometryPerMaterialBatch.prototype.update = function (time) {
    var i;
    var items = this._items;
    var length = items.length;

    for (i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.invalidated) {
        items.splice(i, 1);
        var updaters = item.updaters.values;
        var updatersLength = updaters.length;
        for (var h = 0; h < updatersLength; h++) {
          this.add(time, updaters[h]);
        }
        item.destroy();
      }
    }

    var isUpdated = true;
    for (i = 0; i < items.length; i++) {
      isUpdated = items[i].update(time) && isUpdated;
    }
    return isUpdated;
  };

  StaticGeometryPerMaterialBatch.prototype.getBoundingSphere = function (
    updater,
    result
  ) {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      var item = items[i];
      if (item.contains(updater)) {
        return item.getBoundingSphere(updater, result);
      }
    }
    return BoundingSphereState$1.FAILED;
  };

  StaticGeometryPerMaterialBatch.prototype.removeAllPrimitives = function () {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      items[i].destroy();
    }
    this._items.length = 0;
  };

  var colorScratch$4 = new Color();
  var distanceDisplayConditionScratch$3 = new DistanceDisplayCondition();
  var defaultDistanceDisplayCondition$3 = new DistanceDisplayCondition();

  function Batch$2(primitives, classificationType, color, zIndex) {
    this.primitives = primitives;
    this.zIndex = zIndex;
    this.classificationType = classificationType;
    this.color = color;
    this.createPrimitive = false;
    this.waitingOnCreate = false;
    this.primitive = undefined;
    this.oldPrimitive = undefined;
    this.geometry = new AssociativeArray();
    this.updaters = new AssociativeArray();
    this.updatersWithAttributes = new AssociativeArray();
    this.attributes = new AssociativeArray();
    this.subscriptions = new AssociativeArray();
    this.showsUpdated = new AssociativeArray();
    this.itemsToRemove = [];
    this.isDirty = false;
    this.rectangleCollisionCheck = new RectangleCollisionChecker();
  }

  Batch$2.prototype.overlapping = function (rectangle) {
    return this.rectangleCollisionCheck.collides(rectangle);
  };

  Batch$2.prototype.add = function (updater, instance) {
    var id = updater.id;
    this.createPrimitive = true;
    this.geometry.set(id, instance);
    this.updaters.set(id, updater);
    this.rectangleCollisionCheck.insert(id, instance.geometry.rectangle);
    if (
      !updater.hasConstantFill ||
      !updater.fillMaterialProperty.isConstant ||
      !Property.isConstant(updater.distanceDisplayConditionProperty)
    ) {
      this.updatersWithAttributes.set(id, updater);
    } else {
      var that = this;
      this.subscriptions.set(
        id,
        updater.entity.definitionChanged.addEventListener(function (
          entity,
          propertyName,
          newValue,
          oldValue
        ) {
          if (propertyName === "isShowing") {
            that.showsUpdated.set(updater.id, updater);
          }
        })
      );
    }
  };

  Batch$2.prototype.remove = function (updater) {
    var id = updater.id;
    var geometryInstance = this.geometry.get(id);
    this.createPrimitive = this.geometry.remove(id) || this.createPrimitive;
    if (this.updaters.remove(id)) {
      this.rectangleCollisionCheck.remove(
        id,
        geometryInstance.geometry.rectangle
      );
      this.updatersWithAttributes.remove(id);
      var unsubscribe = this.subscriptions.get(id);
      if (defined(unsubscribe)) {
        unsubscribe();
        this.subscriptions.remove(id);
        this.showsUpdated.remove(id);
      }
      return true;
    }
    return false;
  };

  Batch$2.prototype.update = function (time) {
    var isUpdated = true;
    var removedCount = 0;
    var primitive = this.primitive;
    var primitives = this.primitives;
    var i;

    if (this.createPrimitive) {
      var geometries = this.geometry.values;
      var geometriesLength = geometries.length;
      if (geometriesLength > 0) {
        if (defined(primitive)) {
          if (!defined(this.oldPrimitive)) {
            this.oldPrimitive = primitive;
          } else {
            primitives.remove(primitive);
          }
        }

        primitive = new GroundPrimitive({
          show: false,
          asynchronous: true,
          geometryInstances: geometries.slice(),
          classificationType: this.classificationType,
        });
        primitives.add(primitive, this.zIndex);
        isUpdated = false;
      } else {
        if (defined(primitive)) {
          primitives.remove(primitive);
          primitive = undefined;
        }
        var oldPrimitive = this.oldPrimitive;
        if (defined(oldPrimitive)) {
          primitives.remove(oldPrimitive);
          this.oldPrimitive = undefined;
        }
      }

      this.attributes.removeAll();
      this.primitive = primitive;
      this.createPrimitive = false;
      this.waitingOnCreate = true;
    } else if (defined(primitive) && primitive.ready) {
      primitive.show = true;
      if (defined(this.oldPrimitive)) {
        primitives.remove(this.oldPrimitive);
        this.oldPrimitive = undefined;
      }
      var updatersWithAttributes = this.updatersWithAttributes.values;
      var length = updatersWithAttributes.length;
      var waitingOnCreate = this.waitingOnCreate;
      for (i = 0; i < length; i++) {
        var updater = updatersWithAttributes[i];
        var instance = this.geometry.get(updater.id);

        var attributes = this.attributes.get(instance.id.id);
        if (!defined(attributes)) {
          attributes = primitive.getGeometryInstanceAttributes(instance.id);
          this.attributes.set(instance.id.id, attributes);
        }

        if (!updater.fillMaterialProperty.isConstant || waitingOnCreate) {
          var colorProperty = updater.fillMaterialProperty.color;
          var fillColor = Property.getValueOrDefault(
            colorProperty,
            time,
            Color.WHITE,
            colorScratch$4
          );

          if (!Color.equals(attributes._lastColor, fillColor)) {
            attributes._lastColor = Color.clone(fillColor, attributes._lastColor);
            attributes.color = ColorGeometryInstanceAttribute.toValue(
              fillColor,
              attributes.color
            );
          }
        }

        var show =
          updater.entity.isShowing &&
          (updater.hasConstantFill || updater.isFilled(time));
        var currentShow = attributes.show[0] === 1;
        if (show !== currentShow) {
          attributes.show = ShowGeometryInstanceAttribute.toValue(
            show,
            attributes.show
          );
        }

        var distanceDisplayConditionProperty =
          updater.distanceDisplayConditionProperty;
        if (!Property.isConstant(distanceDisplayConditionProperty)) {
          var distanceDisplayCondition = Property.getValueOrDefault(
            distanceDisplayConditionProperty,
            time,
            defaultDistanceDisplayCondition$3,
            distanceDisplayConditionScratch$3
          );
          if (
            !DistanceDisplayCondition.equals(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            )
          ) {
            attributes._lastDistanceDisplayCondition = DistanceDisplayCondition.clone(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            );
            attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
              distanceDisplayCondition,
              attributes.distanceDisplayCondition
            );
          }
        }
      }

      this.updateShows(primitive);
      this.waitingOnCreate = false;
    } else if (defined(primitive) && !primitive.ready) {
      isUpdated = false;
    }
    this.itemsToRemove.length = removedCount;
    return isUpdated;
  };

  Batch$2.prototype.updateShows = function (primitive) {
    var showsUpdated = this.showsUpdated.values;
    var length = showsUpdated.length;
    for (var i = 0; i < length; i++) {
      var updater = showsUpdated[i];
      var instance = this.geometry.get(updater.id);

      var attributes = this.attributes.get(instance.id.id);
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(instance.id);
        this.attributes.set(instance.id.id, attributes);
      }

      var show = updater.entity.isShowing;
      var currentShow = attributes.show[0] === 1;
      if (show !== currentShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          show,
          attributes.show
        );
        instance.attributes.show.value[0] = attributes.show[0];
      }
    }
    this.showsUpdated.removeAll();
  };

  Batch$2.prototype.contains = function (updater) {
    return this.updaters.contains(updater.id);
  };

  Batch$2.prototype.getBoundingSphere = function (updater, result) {
    var primitive = this.primitive;
    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }

    var bs = primitive.getBoundingSphere(updater.entity);
    if (!defined(bs)) {
      return BoundingSphereState$1.FAILED;
    }

    bs.clone(result);
    return BoundingSphereState$1.DONE;
  };

  Batch$2.prototype.removeAllPrimitives = function () {
    var primitives = this.primitives;

    var primitive = this.primitive;
    if (defined(primitive)) {
      primitives.remove(primitive);
      this.primitive = undefined;
      this.geometry.removeAll();
      this.updaters.removeAll();
    }

    var oldPrimitive = this.oldPrimitive;
    if (defined(oldPrimitive)) {
      primitives.remove(oldPrimitive);
      this.oldPrimitive = undefined;
    }
  };

  /**
   * @private
   */
  function StaticGroundGeometryColorBatch(primitives, classificationType) {
    this._batches = [];
    this._primitives = primitives;
    this._classificationType = classificationType;
  }

  StaticGroundGeometryColorBatch.prototype.add = function (time, updater) {
    var instance = updater.createFillGeometryInstance(time);
    var batches = this._batches;
    var zIndex = Property.getValueOrDefault(updater.zIndex, 0);
    var batch;
    var length = batches.length;
    for (var i = 0; i < length; ++i) {
      var item = batches[i];
      if (
        item.zIndex === zIndex &&
        !item.overlapping(instance.geometry.rectangle)
      ) {
        batch = item;
        break;
      }
    }

    if (!defined(batch)) {
      batch = new Batch$2(
        this._primitives,
        this._classificationType,
        instance.attributes.color.value,
        zIndex
      );
      batches.push(batch);
    }
    batch.add(updater, instance);
    return batch;
  };

  StaticGroundGeometryColorBatch.prototype.remove = function (updater) {
    var batches = this._batches;
    var count = batches.length;
    for (var i = 0; i < count; ++i) {
      if (batches[i].remove(updater)) {
        return;
      }
    }
  };

  StaticGroundGeometryColorBatch.prototype.update = function (time) {
    var i;
    var updater;

    //Perform initial update
    var isUpdated = true;
    var batches = this._batches;
    var batchCount = batches.length;
    for (i = 0; i < batchCount; ++i) {
      isUpdated = batches[i].update(time) && isUpdated;
    }

    //If any items swapped between batches we need to move them
    for (i = 0; i < batchCount; ++i) {
      var oldBatch = batches[i];
      var itemsToRemove = oldBatch.itemsToRemove;
      var itemsToMoveLength = itemsToRemove.length;
      for (var j = 0; j < itemsToMoveLength; j++) {
        updater = itemsToRemove[j];
        oldBatch.remove(updater);
        var newBatch = this.add(time, updater);
        oldBatch.isDirty = true;
        newBatch.isDirty = true;
      }
    }

    //If we moved anything around, we need to re-build the primitive and remove empty batches
    for (i = batchCount - 1; i >= 0; --i) {
      var batch = batches[i];
      if (batch.isDirty) {
        isUpdated = batches[i].update(time) && isUpdated;
        batch.isDirty = false;
      }
      if (batch.geometry.length === 0) {
        batches.splice(i, 1);
      }
    }

    return isUpdated;
  };

  StaticGroundGeometryColorBatch.prototype.getBoundingSphere = function (
    updater,
    result
  ) {
    var batches = this._batches;
    var batchCount = batches.length;
    for (var i = 0; i < batchCount; ++i) {
      var batch = batches[i];
      if (batch.contains(updater)) {
        return batch.getBoundingSphere(updater, result);
      }
    }

    return BoundingSphereState$1.FAILED;
  };

  StaticGroundGeometryColorBatch.prototype.removeAllPrimitives = function () {
    var batches = this._batches;
    var batchCount = batches.length;
    for (var i = 0; i < batchCount; ++i) {
      batches[i].removeAllPrimitives();
    }
  };

  var distanceDisplayConditionScratch$4 = new DistanceDisplayCondition();
  var defaultDistanceDisplayCondition$4 = new DistanceDisplayCondition();

  // Encapsulates a Primitive and all the entities that it represents.
  function Batch$3(
    primitives,
    classificationType,
    appearanceType,
    materialProperty,
    usingSphericalTextureCoordinates,
    zIndex
  ) {
    this.primitives = primitives; // scene level primitive collection
    this.classificationType = classificationType;
    this.appearanceType = appearanceType;
    this.materialProperty = materialProperty;
    this.updaters = new AssociativeArray();
    this.createPrimitive = true;
    this.primitive = undefined; // a GroundPrimitive encapsulating all the entities
    this.oldPrimitive = undefined;
    this.geometry = new AssociativeArray();
    this.material = undefined;
    this.updatersWithAttributes = new AssociativeArray();
    this.attributes = new AssociativeArray();
    this.invalidated = false;
    this.removeMaterialSubscription = materialProperty.definitionChanged.addEventListener(
      Batch$3.prototype.onMaterialChanged,
      this
    );
    this.subscriptions = new AssociativeArray();
    this.showsUpdated = new AssociativeArray();
    this.usingSphericalTextureCoordinates = usingSphericalTextureCoordinates;
    this.zIndex = zIndex;
    this.rectangleCollisionCheck = new RectangleCollisionChecker();
  }

  Batch$3.prototype.onMaterialChanged = function () {
    this.invalidated = true;
  };

  Batch$3.prototype.overlapping = function (rectangle) {
    return this.rectangleCollisionCheck.collides(rectangle);
  };

  // Check if the given updater's material is compatible with this batch
  Batch$3.prototype.isMaterial = function (updater) {
    var material = this.materialProperty;
    var updaterMaterial = updater.fillMaterialProperty;

    if (
      updaterMaterial === material ||
      (updaterMaterial instanceof ColorMaterialProperty &&
        material instanceof ColorMaterialProperty)
    ) {
      return true;
    }
    return defined(material) && material.equals(updaterMaterial);
  };

  Batch$3.prototype.add = function (time, updater, geometryInstance) {
    var id = updater.id;
    this.updaters.set(id, updater);
    this.geometry.set(id, geometryInstance);
    this.rectangleCollisionCheck.insert(id, geometryInstance.geometry.rectangle);
    // Updaters with dynamic attributes must be tracked separately, may exit the batch
    if (
      !updater.hasConstantFill ||
      !updater.fillMaterialProperty.isConstant ||
      !Property.isConstant(updater.distanceDisplayConditionProperty)
    ) {
      this.updatersWithAttributes.set(id, updater);
    } else {
      var that = this;
      // Listen for show changes. These will be synchronized in updateShows.
      this.subscriptions.set(
        id,
        updater.entity.definitionChanged.addEventListener(function (
          entity,
          propertyName,
          newValue,
          oldValue
        ) {
          if (propertyName === "isShowing") {
            that.showsUpdated.set(updater.id, updater);
          }
        })
      );
    }
    this.createPrimitive = true;
  };

  Batch$3.prototype.remove = function (updater) {
    var id = updater.id;
    var geometryInstance = this.geometry.get(id);
    this.createPrimitive = this.geometry.remove(id) || this.createPrimitive;
    if (this.updaters.remove(id)) {
      this.rectangleCollisionCheck.remove(
        id,
        geometryInstance.geometry.rectangle
      );
      this.updatersWithAttributes.remove(id);
      var unsubscribe = this.subscriptions.get(id);
      if (defined(unsubscribe)) {
        unsubscribe();
        this.subscriptions.remove(id);
      }
      return true;
    }
    return false;
  };

  Batch$3.prototype.update = function (time) {
    var isUpdated = true;
    var primitive = this.primitive;
    var primitives = this.primitives;
    var geometries = this.geometry.values;
    var i;

    if (this.createPrimitive) {
      var geometriesLength = geometries.length;
      if (geometriesLength > 0) {
        if (defined(primitive)) {
          // Keep a handle to the old primitive so it can be removed when the updated version is ready.
          if (!defined(this.oldPrimitive)) {
            this.oldPrimitive = primitive;
          } else {
            // For if the new primitive changes again before it is ready.
            primitives.remove(primitive);
          }
        }

        this.material = MaterialProperty.getValue(
          time,
          this.materialProperty,
          this.material
        );

        primitive = new GroundPrimitive({
          show: false,
          asynchronous: true,
          geometryInstances: geometries.slice(),
          appearance: new this.appearanceType({
            material: this.material,
            // translucent and closed properties overridden
          }),
          classificationType: this.classificationType,
        });

        primitives.add(primitive, this.zIndex);
        isUpdated = false;
      } else {
        if (defined(primitive)) {
          primitives.remove(primitive);
          primitive = undefined;
        }
        var oldPrimitive = this.oldPrimitive;
        if (defined(oldPrimitive)) {
          primitives.remove(oldPrimitive);
          this.oldPrimitive = undefined;
        }
      }

      this.attributes.removeAll();
      this.primitive = primitive;
      this.createPrimitive = false;
    } else if (defined(primitive) && primitive.ready) {
      primitive.show = true;
      if (defined(this.oldPrimitive)) {
        primitives.remove(this.oldPrimitive);
        this.oldPrimitive = undefined;
      }

      this.material = MaterialProperty.getValue(
        time,
        this.materialProperty,
        this.material
      );
      this.primitive.appearance.material = this.material;

      var updatersWithAttributes = this.updatersWithAttributes.values;
      var length = updatersWithAttributes.length;
      for (i = 0; i < length; i++) {
        var updater = updatersWithAttributes[i];
        var entity = updater.entity;
        var instance = this.geometry.get(updater.id);

        var attributes = this.attributes.get(instance.id.id);
        if (!defined(attributes)) {
          attributes = primitive.getGeometryInstanceAttributes(instance.id);
          this.attributes.set(instance.id.id, attributes);
        }

        var show =
          entity.isShowing && (updater.hasConstantFill || updater.isFilled(time));
        var currentShow = attributes.show[0] === 1;
        if (show !== currentShow) {
          attributes.show = ShowGeometryInstanceAttribute.toValue(
            show,
            attributes.show
          );
        }

        var distanceDisplayConditionProperty =
          updater.distanceDisplayConditionProperty;
        if (!Property.isConstant(distanceDisplayConditionProperty)) {
          var distanceDisplayCondition = Property.getValueOrDefault(
            distanceDisplayConditionProperty,
            time,
            defaultDistanceDisplayCondition$4,
            distanceDisplayConditionScratch$4
          );
          if (
            !DistanceDisplayCondition.equals(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            )
          ) {
            attributes._lastDistanceDisplayCondition = DistanceDisplayCondition.clone(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            );
            attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
              distanceDisplayCondition,
              attributes.distanceDisplayCondition
            );
          }
        }
      }

      this.updateShows(primitive);
    } else if (defined(primitive) && !primitive.ready) {
      isUpdated = false;
    }
    return isUpdated;
  };

  Batch$3.prototype.updateShows = function (primitive) {
    var showsUpdated = this.showsUpdated.values;
    var length = showsUpdated.length;
    for (var i = 0; i < length; i++) {
      var updater = showsUpdated[i];
      var entity = updater.entity;
      var instance = this.geometry.get(updater.id);

      var attributes = this.attributes.get(instance.id.id);
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(instance.id);
        this.attributes.set(instance.id.id, attributes);
      }

      var show = entity.isShowing;
      var currentShow = attributes.show[0] === 1;
      if (show !== currentShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          show,
          attributes.show
        );
        instance.attributes.show.value[0] = attributes.show[0];
      }
    }
    this.showsUpdated.removeAll();
  };

  Batch$3.prototype.contains = function (updater) {
    return this.updaters.contains(updater.id);
  };

  Batch$3.prototype.getBoundingSphere = function (updater, result) {
    var primitive = this.primitive;
    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }
    var attributes = primitive.getGeometryInstanceAttributes(updater.entity);
    if (
      !defined(attributes) ||
      !defined(attributes.boundingSphere) ||
      (defined(attributes.show) && attributes.show[0] === 0)
    ) {
      return BoundingSphereState$1.FAILED;
    }
    attributes.boundingSphere.clone(result);
    return BoundingSphereState$1.DONE;
  };

  Batch$3.prototype.destroy = function () {
    var primitive = this.primitive;
    var primitives = this.primitives;
    if (defined(primitive)) {
      primitives.remove(primitive);
    }
    var oldPrimitive = this.oldPrimitive;
    if (defined(oldPrimitive)) {
      primitives.remove(oldPrimitive);
    }
    this.removeMaterialSubscription();
  };

  /**
   * @private
   */
  function StaticGroundGeometryPerMaterialBatch(
    primitives,
    classificationType,
    appearanceType
  ) {
    this._items = [];
    this._primitives = primitives;
    this._classificationType = classificationType;
    this._appearanceType = appearanceType;
  }

  StaticGroundGeometryPerMaterialBatch.prototype.add = function (time, updater) {
    var items = this._items;
    var length = items.length;
    var geometryInstance = updater.createFillGeometryInstance(time);
    var usingSphericalTextureCoordinates = ShadowVolumeAppearance.shouldUseSphericalCoordinates(
      geometryInstance.geometry.rectangle
    );
    var zIndex = Property.getValueOrDefault(updater.zIndex, 0);
    // Check if the Entity represented by the updater can be placed in an existing batch. Requirements:
    // * compatible material (same material or same color)
    // * same type of texture coordinates (spherical vs. planar)
    // * conservatively non-overlapping with any entities in the existing batch
    for (var i = 0; i < length; ++i) {
      var item = items[i];
      if (
        item.isMaterial(updater) &&
        item.usingSphericalTextureCoordinates ===
          usingSphericalTextureCoordinates &&
        item.zIndex === zIndex &&
        !item.overlapping(geometryInstance.geometry.rectangle)
      ) {
        item.add(time, updater, geometryInstance);
        return;
      }
    }
    // If a compatible batch wasn't found, create a new batch.
    var batch = new Batch$3(
      this._primitives,
      this._classificationType,
      this._appearanceType,
      updater.fillMaterialProperty,
      usingSphericalTextureCoordinates,
      zIndex
    );
    batch.add(time, updater, geometryInstance);
    items.push(batch);
  };

  StaticGroundGeometryPerMaterialBatch.prototype.remove = function (updater) {
    var items = this._items;
    var length = items.length;
    for (var i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.remove(updater)) {
        if (item.updaters.length === 0) {
          items.splice(i, 1);
          item.destroy();
        }
        break;
      }
    }
  };

  StaticGroundGeometryPerMaterialBatch.prototype.update = function (time) {
    var i;
    var items = this._items;
    var length = items.length;

    for (i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.invalidated) {
        items.splice(i, 1);
        var updaters = item.updaters.values;
        var updatersLength = updaters.length;
        for (var h = 0; h < updatersLength; h++) {
          this.add(time, updaters[h]);
        }
        item.destroy();
      }
    }

    var isUpdated = true;
    for (i = 0; i < items.length; i++) {
      isUpdated = items[i].update(time) && isUpdated;
    }
    return isUpdated;
  };

  StaticGroundGeometryPerMaterialBatch.prototype.getBoundingSphere = function (
    updater,
    result
  ) {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      var item = items[i];
      if (item.contains(updater)) {
        return item.getBoundingSphere(updater, result);
      }
    }
    return BoundingSphereState$1.FAILED;
  };

  StaticGroundGeometryPerMaterialBatch.prototype.removeAllPrimitives = function () {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      items[i].destroy();
    }
    this._items.length = 0;
  };

  var colorScratch$5 = new Color();
  var distanceDisplayConditionScratch$5 = new DistanceDisplayCondition();
  var defaultDistanceDisplayCondition$5 = new DistanceDisplayCondition();
  var defaultOffset$a = Cartesian3.ZERO;
  var offsetScratch$c = new Cartesian3();

  function Batch$4(primitives, translucent, width, shadows) {
    this.translucent = translucent;
    this.width = width;
    this.shadows = shadows;
    this.primitives = primitives;
    this.createPrimitive = false;
    this.waitingOnCreate = false;
    this.primitive = undefined;
    this.oldPrimitive = undefined;
    this.geometry = new AssociativeArray();
    this.updaters = new AssociativeArray();
    this.updatersWithAttributes = new AssociativeArray();
    this.attributes = new AssociativeArray();
    this.itemsToRemove = [];
    this.subscriptions = new AssociativeArray();
    this.showsUpdated = new AssociativeArray();
  }
  Batch$4.prototype.add = function (updater, instance) {
    var id = updater.id;
    this.createPrimitive = true;
    this.geometry.set(id, instance);
    this.updaters.set(id, updater);
    if (
      !updater.hasConstantOutline ||
      !updater.outlineColorProperty.isConstant ||
      !Property.isConstant(updater.distanceDisplayConditionProperty) ||
      !Property.isConstant(updater.terrainOffsetProperty)
    ) {
      this.updatersWithAttributes.set(id, updater);
    } else {
      var that = this;
      this.subscriptions.set(
        id,
        updater.entity.definitionChanged.addEventListener(function (
          entity,
          propertyName,
          newValue,
          oldValue
        ) {
          if (propertyName === "isShowing") {
            that.showsUpdated.set(updater.id, updater);
          }
        })
      );
    }
  };

  Batch$4.prototype.remove = function (updater) {
    var id = updater.id;
    this.createPrimitive = this.geometry.remove(id) || this.createPrimitive;
    if (this.updaters.remove(id)) {
      this.updatersWithAttributes.remove(id);
      var unsubscribe = this.subscriptions.get(id);
      if (defined(unsubscribe)) {
        unsubscribe();
        this.subscriptions.remove(id);
        this.showsUpdated.remove(id);
      }
      return true;
    }
    return false;
  };

  Batch$4.prototype.update = function (time) {
    var isUpdated = true;
    var removedCount = 0;
    var primitive = this.primitive;
    var primitives = this.primitives;
    var i;

    if (this.createPrimitive) {
      var geometries = this.geometry.values;
      var geometriesLength = geometries.length;
      if (geometriesLength > 0) {
        if (defined(primitive)) {
          if (!defined(this.oldPrimitive)) {
            this.oldPrimitive = primitive;
          } else {
            primitives.remove(primitive);
          }
        }

        primitive = new Primitive({
          show: false,
          asynchronous: true,
          geometryInstances: geometries.slice(),
          appearance: new PerInstanceColorAppearance({
            flat: true,
            translucent: this.translucent,
            renderState: {
              lineWidth: this.width,
            },
          }),
          shadows: this.shadows,
        });

        primitives.add(primitive);
        isUpdated = false;
      } else {
        if (defined(primitive)) {
          primitives.remove(primitive);
          primitive = undefined;
        }
        var oldPrimitive = this.oldPrimitive;
        if (defined(oldPrimitive)) {
          primitives.remove(oldPrimitive);
          this.oldPrimitive = undefined;
        }
      }

      this.attributes.removeAll();
      this.primitive = primitive;
      this.createPrimitive = false;
      this.waitingOnCreate = true;
    } else if (defined(primitive) && primitive.ready) {
      primitive.show = true;
      if (defined(this.oldPrimitive)) {
        primitives.remove(this.oldPrimitive);
        this.oldPrimitive = undefined;
      }

      var updatersWithAttributes = this.updatersWithAttributes.values;
      var length = updatersWithAttributes.length;
      var waitingOnCreate = this.waitingOnCreate;
      for (i = 0; i < length; i++) {
        var updater = updatersWithAttributes[i];
        var instance = this.geometry.get(updater.id);

        var attributes = this.attributes.get(instance.id.id);
        if (!defined(attributes)) {
          attributes = primitive.getGeometryInstanceAttributes(instance.id);
          this.attributes.set(instance.id.id, attributes);
        }

        if (!updater.outlineColorProperty.isConstant || waitingOnCreate) {
          var outlineColorProperty = updater.outlineColorProperty;
          var outlineColor = Property.getValueOrDefault(
            outlineColorProperty,
            time,
            Color.WHITE,
            colorScratch$5
          );
          if (!Color.equals(attributes._lastColor, outlineColor)) {
            attributes._lastColor = Color.clone(
              outlineColor,
              attributes._lastColor
            );
            attributes.color = ColorGeometryInstanceAttribute.toValue(
              outlineColor,
              attributes.color
            );
            if (
              (this.translucent && attributes.color[3] === 255) ||
              (!this.translucent && attributes.color[3] !== 255)
            ) {
              this.itemsToRemove[removedCount++] = updater;
            }
          }
        }

        var show =
          updater.entity.isShowing &&
          (updater.hasConstantOutline || updater.isOutlineVisible(time));
        var currentShow = attributes.show[0] === 1;
        if (show !== currentShow) {
          attributes.show = ShowGeometryInstanceAttribute.toValue(
            show,
            attributes.show
          );
        }

        var distanceDisplayConditionProperty =
          updater.distanceDisplayConditionProperty;
        if (!Property.isConstant(distanceDisplayConditionProperty)) {
          var distanceDisplayCondition = Property.getValueOrDefault(
            distanceDisplayConditionProperty,
            time,
            defaultDistanceDisplayCondition$5,
            distanceDisplayConditionScratch$5
          );
          if (
            !DistanceDisplayCondition.equals(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            )
          ) {
            attributes._lastDistanceDisplayCondition = DistanceDisplayCondition.clone(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            );
            attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
              distanceDisplayCondition,
              attributes.distanceDisplayCondition
            );
          }
        }

        var offsetProperty = updater.terrainOffsetProperty;
        if (!Property.isConstant(offsetProperty)) {
          var offset = Property.getValueOrDefault(
            offsetProperty,
            time,
            defaultOffset$a,
            offsetScratch$c
          );
          if (!Cartesian3.equals(offset, attributes._lastOffset)) {
            attributes._lastOffset = Cartesian3.clone(
              offset,
              attributes._lastOffset
            );
            attributes.offset = OffsetGeometryInstanceAttribute.toValue(
              offset,
              attributes.offset
            );
          }
        }
      }

      this.updateShows(primitive);
      this.waitingOnCreate = false;
    } else if (defined(primitive) && !primitive.ready) {
      isUpdated = false;
    }

    this.itemsToRemove.length = removedCount;
    return isUpdated;
  };

  Batch$4.prototype.updateShows = function (primitive) {
    var showsUpdated = this.showsUpdated.values;
    var length = showsUpdated.length;
    for (var i = 0; i < length; i++) {
      var updater = showsUpdated[i];
      var instance = this.geometry.get(updater.id);

      var attributes = this.attributes.get(instance.id.id);
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(instance.id);
        this.attributes.set(instance.id.id, attributes);
      }

      var show = updater.entity.isShowing;
      var currentShow = attributes.show[0] === 1;
      if (show !== currentShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          show,
          attributes.show
        );
        instance.attributes.show.value[0] = attributes.show[0];
      }
    }
    this.showsUpdated.removeAll();
  };

  Batch$4.prototype.contains = function (updater) {
    return this.updaters.contains(updater.id);
  };

  Batch$4.prototype.getBoundingSphere = function (updater, result) {
    var primitive = this.primitive;
    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }
    var attributes = primitive.getGeometryInstanceAttributes(updater.entity);
    if (
      !defined(attributes) ||
      !defined(attributes.boundingSphere) || //
      (defined(attributes.show) && attributes.show[0] === 0)
    ) {
      return BoundingSphereState$1.FAILED;
    }
    attributes.boundingSphere.clone(result);
    return BoundingSphereState$1.DONE;
  };

  Batch$4.prototype.removeAllPrimitives = function () {
    var primitives = this.primitives;

    var primitive = this.primitive;
    if (defined(primitive)) {
      primitives.remove(primitive);
      this.primitive = undefined;
      this.geometry.removeAll();
      this.updaters.removeAll();
    }

    var oldPrimitive = this.oldPrimitive;
    if (defined(oldPrimitive)) {
      primitives.remove(oldPrimitive);
      this.oldPrimitive = undefined;
    }
  };

  /**
   * @private
   */
  function StaticOutlineGeometryBatch(primitives, scene, shadows) {
    this._primitives = primitives;
    this._scene = scene;
    this._shadows = shadows;
    this._solidBatches = new AssociativeArray();
    this._translucentBatches = new AssociativeArray();
  }
  StaticOutlineGeometryBatch.prototype.add = function (time, updater) {
    var instance = updater.createOutlineGeometryInstance(time);
    var width = this._scene.clampLineWidth(updater.outlineWidth);
    var batches;
    var batch;
    if (instance.attributes.color.value[3] === 255) {
      batches = this._solidBatches;
      batch = batches.get(width);
      if (!defined(batch)) {
        batch = new Batch$4(this._primitives, false, width, this._shadows);
        batches.set(width, batch);
      }
      batch.add(updater, instance);
    } else {
      batches = this._translucentBatches;
      batch = batches.get(width);
      if (!defined(batch)) {
        batch = new Batch$4(this._primitives, true, width, this._shadows);
        batches.set(width, batch);
      }
      batch.add(updater, instance);
    }
  };

  StaticOutlineGeometryBatch.prototype.remove = function (updater) {
    var i;

    var solidBatches = this._solidBatches.values;
    var solidBatchesLength = solidBatches.length;
    for (i = 0; i < solidBatchesLength; i++) {
      if (solidBatches[i].remove(updater)) {
        return;
      }
    }

    var translucentBatches = this._translucentBatches.values;
    var translucentBatchesLength = translucentBatches.length;
    for (i = 0; i < translucentBatchesLength; i++) {
      if (translucentBatches[i].remove(updater)) {
        return;
      }
    }
  };

  StaticOutlineGeometryBatch.prototype.update = function (time) {
    var i;
    var x;
    var updater;
    var batch;
    var solidBatches = this._solidBatches.values;
    var solidBatchesLength = solidBatches.length;
    var translucentBatches = this._translucentBatches.values;
    var translucentBatchesLength = translucentBatches.length;
    var itemsToRemove;
    var isUpdated = true;
    var needUpdate = false;

    do {
      needUpdate = false;
      for (x = 0; x < solidBatchesLength; x++) {
        batch = solidBatches[x];
        //Perform initial update
        isUpdated = batch.update(time);

        //If any items swapped between solid/translucent, we need to
        //move them between batches
        itemsToRemove = batch.itemsToRemove;
        var solidsToMoveLength = itemsToRemove.length;
        if (solidsToMoveLength > 0) {
          needUpdate = true;
          for (i = 0; i < solidsToMoveLength; i++) {
            updater = itemsToRemove[i];
            batch.remove(updater);
            this.add(time, updater);
          }
        }
      }
      for (x = 0; x < translucentBatchesLength; x++) {
        batch = translucentBatches[x];
        //Perform initial update
        isUpdated = batch.update(time);

        //If any items swapped between solid/translucent, we need to
        //move them between batches
        itemsToRemove = batch.itemsToRemove;
        var translucentToMoveLength = itemsToRemove.length;
        if (translucentToMoveLength > 0) {
          needUpdate = true;
          for (i = 0; i < translucentToMoveLength; i++) {
            updater = itemsToRemove[i];
            batch.remove(updater);
            this.add(time, updater);
          }
        }
      }
    } while (needUpdate);

    return isUpdated;
  };

  StaticOutlineGeometryBatch.prototype.getBoundingSphere = function (
    updater,
    result
  ) {
    var i;

    var solidBatches = this._solidBatches.values;
    var solidBatchesLength = solidBatches.length;
    for (i = 0; i < solidBatchesLength; i++) {
      var solidBatch = solidBatches[i];
      if (solidBatch.contains(updater)) {
        return solidBatch.getBoundingSphere(updater, result);
      }
    }

    var translucentBatches = this._translucentBatches.values;
    var translucentBatchesLength = translucentBatches.length;
    for (i = 0; i < translucentBatchesLength; i++) {
      var translucentBatch = translucentBatches[i];
      if (translucentBatch.contains(updater)) {
        return translucentBatch.getBoundingSphere(updater, result);
      }
    }

    return BoundingSphereState$1.FAILED;
  };

  StaticOutlineGeometryBatch.prototype.removeAllPrimitives = function () {
    var i;

    var solidBatches = this._solidBatches.values;
    var solidBatchesLength = solidBatches.length;
    for (i = 0; i < solidBatchesLength; i++) {
      solidBatches[i].removeAllPrimitives();
    }

    var translucentBatches = this._translucentBatches.values;
    var translucentBatchesLength = translucentBatches.length;
    for (i = 0; i < translucentBatchesLength; i++) {
      translucentBatches[i].removeAllPrimitives();
    }
  };

  var scratchColor$h = new Color();

  function WallGeometryOptions(entity) {
    this.id = entity;
    this.vertexFormat = undefined;
    this.positions = undefined;
    this.minimumHeights = undefined;
    this.maximumHeights = undefined;
    this.granularity = undefined;
  }

  /**
   * A {@link GeometryUpdater} for walls.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias WallGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function WallGeometryUpdater(entity, scene) {
    GeometryUpdater.call(this, {
      entity: entity,
      scene: scene,
      geometryOptions: new WallGeometryOptions(entity),
      geometryPropertyName: "wall",
      observedPropertyNames: ["availability", "wall"],
    });

    this._onEntityPropertyChanged(entity, "wall", entity.wall, undefined);
  }

  if (defined(Object.create)) {
    WallGeometryUpdater.prototype = Object.create(GeometryUpdater.prototype);
    WallGeometryUpdater.prototype.constructor = WallGeometryUpdater;
  }

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  WallGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);

    var attributes;

    var color;
    var show = new ShowGeometryInstanceAttribute(
      isAvailable &&
        entity.isShowing &&
        this._showProperty.getValue(time) &&
        this._fillProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );
    if (this._materialProperty instanceof ColorMaterialProperty) {
      var currentColor;
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$h);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      color = ColorGeometryInstanceAttribute.fromColor(currentColor);
      attributes = {
        show: show,
        distanceDisplayCondition: distanceDisplayConditionAttribute,
        color: color,
      };
    } else {
      attributes = {
        show: show,
        distanceDisplayCondition: distanceDisplayConditionAttribute,
      };
    }

    return new GeometryInstance({
      id: entity,
      geometry: new WallGeometry(this._options),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  WallGeometryUpdater.prototype.createOutlineGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);

    if (!this._outlineEnabled) {
      throw new DeveloperError(
        "This instance does not represent an outlined geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var outlineColor = Property.getValueOrDefault(
      this._outlineColorProperty,
      time,
      Color.BLACK,
      scratchColor$h
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );

    return new GeometryInstance({
      id: entity,
      geometry: new WallOutlineGeometry(this._options),
      attributes: {
        show: new ShowGeometryInstanceAttribute(
          isAvailable &&
            entity.isShowing &&
            this._showProperty.getValue(time) &&
            this._showOutlineProperty.getValue(time)
        ),
        color: ColorGeometryInstanceAttribute.fromColor(outlineColor),
        distanceDisplayCondition: DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
          distanceDisplayCondition
        ),
      },
    });
  };

  WallGeometryUpdater.prototype._isHidden = function (entity, wall) {
    return (
      !defined(wall.positions) ||
      GeometryUpdater.prototype._isHidden.call(this, entity, wall)
    );
  };

  WallGeometryUpdater.prototype._getIsClosed = function (options) {
    return false;
  };

  WallGeometryUpdater.prototype._isDynamic = function (entity, wall) {
    return (
      !wall.positions.isConstant || //
      !Property.isConstant(wall.minimumHeights) || //
      !Property.isConstant(wall.maximumHeights) || //
      !Property.isConstant(wall.outlineWidth) || //
      !Property.isConstant(wall.granularity)
    );
  };

  WallGeometryUpdater.prototype._setStaticOptions = function (entity, wall) {
    var minimumHeights = wall.minimumHeights;
    var maximumHeights = wall.maximumHeights;
    var granularity = wall.granularity;
    var isColorMaterial = this._materialProperty instanceof ColorMaterialProperty;

    var options = this._options;
    options.vertexFormat = isColorMaterial
      ? PerInstanceColorAppearance.VERTEX_FORMAT
      : MaterialAppearance.MaterialSupport.TEXTURED.vertexFormat;
    options.positions = wall.positions.getValue(
      Iso8601.MINIMUM_VALUE,
      options.positions
    );
    options.minimumHeights = defined(minimumHeights)
      ? minimumHeights.getValue(Iso8601.MINIMUM_VALUE, options.minimumHeights)
      : undefined;
    options.maximumHeights = defined(maximumHeights)
      ? maximumHeights.getValue(Iso8601.MINIMUM_VALUE, options.maximumHeights)
      : undefined;
    options.granularity = defined(granularity)
      ? granularity.getValue(Iso8601.MINIMUM_VALUE)
      : undefined;
  };

  WallGeometryUpdater.DynamicGeometryUpdater = DynamicWallGeometryUpdater;

  /**
   * @private
   */
  function DynamicWallGeometryUpdater(
    geometryUpdater,
    primitives,
    groundPrimitives
  ) {
    DynamicGeometryUpdater.call(
      this,
      geometryUpdater,
      primitives,
      groundPrimitives
    );
  }

  if (defined(Object.create)) {
    DynamicWallGeometryUpdater.prototype = Object.create(
      DynamicGeometryUpdater.prototype
    );
    DynamicWallGeometryUpdater.prototype.constructor = DynamicWallGeometryUpdater;
  }

  DynamicWallGeometryUpdater.prototype._isHidden = function (entity, wall, time) {
    return (
      !defined(this._options.positions) ||
      DynamicGeometryUpdater.prototype._isHidden.call(this, entity, wall, time)
    );
  };

  DynamicWallGeometryUpdater.prototype._setOptions = function (
    entity,
    wall,
    time
  ) {
    var options = this._options;
    options.positions = Property.getValueOrUndefined(
      wall.positions,
      time,
      options.positions
    );
    options.minimumHeights = Property.getValueOrUndefined(
      wall.minimumHeights,
      time,
      options.minimumHeights
    );
    options.maximumHeights = Property.getValueOrUndefined(
      wall.maximumHeights,
      time,
      options.maximumHeights
    );
    options.granularity = Property.getValueOrUndefined(wall.granularity, time);
  };

  var emptyArray = [];

  var geometryUpdaters = [
    BoxGeometryUpdater,
    CylinderGeometryUpdater,
    CorridorGeometryUpdater,
    EllipseGeometryUpdater,
    EllipsoidGeometryUpdater,
    PlaneGeometryUpdater,
    PolygonGeometryUpdater,
    PolylineVolumeGeometryUpdater,
    RectangleGeometryUpdater,
    WallGeometryUpdater,
  ];

  function GeometryUpdaterSet(entity, scene) {
    this.entity = entity;
    this.scene = scene;
    var updaters = new Array(geometryUpdaters.length);
    var geometryChanged = new Event();
    function raiseEvent(geometry) {
      geometryChanged.raiseEvent(geometry);
    }
    var eventHelper = new EventHelper();
    for (var i = 0; i < updaters.length; i++) {
      var updater = new geometryUpdaters[i](entity, scene);
      eventHelper.add(updater.geometryChanged, raiseEvent);
      updaters[i] = updater;
    }
    this.updaters = updaters;
    this.geometryChanged = geometryChanged;
    this.eventHelper = eventHelper;

    this._removeEntitySubscription = entity.definitionChanged.addEventListener(
      GeometryUpdaterSet.prototype._onEntityPropertyChanged,
      this
    );
  }

  GeometryUpdaterSet.prototype._onEntityPropertyChanged = function (
    entity,
    propertyName,
    newValue,
    oldValue
  ) {
    var updaters = this.updaters;
    for (var i = 0; i < updaters.length; i++) {
      updaters[i]._onEntityPropertyChanged(
        entity,
        propertyName,
        newValue,
        oldValue
      );
    }
  };

  GeometryUpdaterSet.prototype.forEach = function (callback) {
    var updaters = this.updaters;
    for (var i = 0; i < updaters.length; i++) {
      callback(updaters[i]);
    }
  };

  GeometryUpdaterSet.prototype.destroy = function () {
    this.eventHelper.removeAll();
    var updaters = this.updaters;
    for (var i = 0; i < updaters.length; i++) {
      updaters[i].destroy();
    }
    this._removeEntitySubscription();
    destroyObject(this);
  };

  /**
   * A general purpose visualizer for geometry represented by {@link Primitive} instances.
   * @alias GeometryVisualizer
   * @constructor
   *
   * @param {Scene} scene The scene the primitives will be rendered in.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   * @param {PrimitiveCollection} [primitives=scene.primitives] A collection to add primitives related to the entities
   * @param {PrimitiveCollection} [groundPrimitives=scene.groundPrimitives] A collection to add ground primitives related to the entities
   */
  function GeometryVisualizer(
    scene,
    entityCollection,
    primitives,
    groundPrimitives
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("scene", scene);
    Check.defined("entityCollection", entityCollection);
    //>>includeEnd('debug');

    primitives = defaultValue(primitives, scene.primitives);
    groundPrimitives = defaultValue(groundPrimitives, scene.groundPrimitives);

    this._scene = scene;
    this._primitives = primitives;
    this._groundPrimitives = groundPrimitives;
    this._entityCollection = undefined;
    this._addedObjects = new AssociativeArray();
    this._removedObjects = new AssociativeArray();
    this._changedObjects = new AssociativeArray();

    var numberOfShadowModes = ShadowMode$1.NUMBER_OF_SHADOW_MODES;
    this._outlineBatches = new Array(numberOfShadowModes * 2);
    this._closedColorBatches = new Array(numberOfShadowModes * 2);
    this._closedMaterialBatches = new Array(numberOfShadowModes * 2);
    this._openColorBatches = new Array(numberOfShadowModes * 2);
    this._openMaterialBatches = new Array(numberOfShadowModes * 2);

    var supportsMaterialsforEntitiesOnTerrain = Entity.supportsMaterialsforEntitiesOnTerrain(
      scene
    );
    this._supportsMaterialsforEntitiesOnTerrain = supportsMaterialsforEntitiesOnTerrain;

    var i;
    for (i = 0; i < numberOfShadowModes; ++i) {
      this._outlineBatches[i] = new StaticOutlineGeometryBatch(
        primitives,
        scene,
        i,
        false
      );
      this._outlineBatches[
        numberOfShadowModes + i
      ] = new StaticOutlineGeometryBatch(primitives, scene, i, true);

      this._closedColorBatches[i] = new StaticGeometryColorBatch(
        primitives,
        PerInstanceColorAppearance,
        undefined,
        true,
        i,
        true
      );
      this._closedColorBatches[
        numberOfShadowModes + i
      ] = new StaticGeometryColorBatch(
        primitives,
        PerInstanceColorAppearance,
        undefined,
        true,
        i,
        false
      );

      this._closedMaterialBatches[i] = new StaticGeometryPerMaterialBatch(
        primitives,
        MaterialAppearance,
        undefined,
        true,
        i,
        true
      );
      this._closedMaterialBatches[
        numberOfShadowModes + i
      ] = new StaticGeometryPerMaterialBatch(
        primitives,
        MaterialAppearance,
        undefined,
        true,
        i,
        false
      );

      this._openColorBatches[i] = new StaticGeometryColorBatch(
        primitives,
        PerInstanceColorAppearance,
        undefined,
        false,
        i,
        true
      );
      this._openColorBatches[
        numberOfShadowModes + i
      ] = new StaticGeometryColorBatch(
        primitives,
        PerInstanceColorAppearance,
        undefined,
        false,
        i,
        false
      );

      this._openMaterialBatches[i] = new StaticGeometryPerMaterialBatch(
        primitives,
        MaterialAppearance,
        undefined,
        false,
        i,
        true
      );
      this._openMaterialBatches[
        numberOfShadowModes + i
      ] = new StaticGeometryPerMaterialBatch(
        primitives,
        MaterialAppearance,
        undefined,
        false,
        i,
        false
      );
    }

    var numberOfClassificationTypes =
      ClassificationType$1.NUMBER_OF_CLASSIFICATION_TYPES;
    var groundColorBatches = new Array(numberOfClassificationTypes);
    var groundMaterialBatches = [];
    if (supportsMaterialsforEntitiesOnTerrain) {
      for (i = 0; i < numberOfClassificationTypes; ++i) {
        groundMaterialBatches.push(
          new StaticGroundGeometryPerMaterialBatch(
            groundPrimitives,
            i,
            MaterialAppearance
          )
        );
        groundColorBatches[i] = new StaticGroundGeometryColorBatch(
          groundPrimitives,
          i
        );
      }
    } else {
      for (i = 0; i < numberOfClassificationTypes; ++i) {
        groundColorBatches[i] = new StaticGroundGeometryColorBatch(
          groundPrimitives,
          i
        );
      }
    }

    this._groundColorBatches = groundColorBatches;
    this._groundMaterialBatches = groundMaterialBatches;

    this._dynamicBatch = new DynamicGeometryBatch(primitives, groundPrimitives);

    this._batches = this._outlineBatches.concat(
      this._closedColorBatches,
      this._closedMaterialBatches,
      this._openColorBatches,
      this._openMaterialBatches,
      this._groundColorBatches,
      this._groundMaterialBatches,
      this._dynamicBatch
    );

    this._subscriptions = new AssociativeArray();
    this._updaterSets = new AssociativeArray();

    this._entityCollection = entityCollection;
    entityCollection.collectionChanged.addEventListener(
      GeometryVisualizer.prototype._onCollectionChanged,
      this
    );
    this._onCollectionChanged(
      entityCollection,
      entityCollection.values,
      emptyArray
    );
  }

  /**
   * Updates all of the primitives created by this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} True if the visualizer successfully updated to the provided time,
   * false if the visualizer is waiting for asynchronous primitives to be created.
   */
  GeometryVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var addedObjects = this._addedObjects;
    var added = addedObjects.values;
    var removedObjects = this._removedObjects;
    var removed = removedObjects.values;
    var changedObjects = this._changedObjects;
    var changed = changedObjects.values;

    var i;
    var entity;
    var id;
    var updaterSet;
    var that = this;

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      id = entity.id;
      updaterSet = this._updaterSets.get(id);

      //If in a single update, an entity gets removed and a new instance
      //re-added with the same id, the updater no longer tracks the
      //correct entity, we need to both remove the old one and
      //add the new one, which is done by pushing the entity
      //onto the removed/added lists.
      if (updaterSet.entity === entity) {
        updaterSet.forEach(function (updater) {
          that._removeUpdater(updater);
          that._insertUpdaterIntoBatch(time, updater);
        });
      } else {
        removed.push(entity);
        added.push(entity);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      id = entity.id;
      updaterSet = this._updaterSets.get(id);
      updaterSet.forEach(this._removeUpdater.bind(this));
      updaterSet.destroy();
      this._updaterSets.remove(id);
      this._subscriptions.get(id)();
      this._subscriptions.remove(id);
    }

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      id = entity.id;
      updaterSet = new GeometryUpdaterSet(entity, this._scene);
      this._updaterSets.set(id, updaterSet);
      updaterSet.forEach(function (updater) {
        that._insertUpdaterIntoBatch(time, updater);
      });
      this._subscriptions.set(
        id,
        updaterSet.geometryChanged.addEventListener(
          GeometryVisualizer._onGeometryChanged,
          this
        )
      );
    }

    addedObjects.removeAll();
    removedObjects.removeAll();
    changedObjects.removeAll();

    var isUpdated = true;
    var batches = this._batches;
    var length = batches.length;
    for (i = 0; i < length; i++) {
      isUpdated = batches[i].update(time) && isUpdated;
    }

    return isUpdated;
  };

  var getBoundingSphereArrayScratch = [];
  var getBoundingSphereBoundingSphereScratch = new BoundingSphere();

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  GeometryVisualizer.prototype.getBoundingSphere = function (entity, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("entity", entity);
    Check.defined("result", result);
    //>>includeEnd('debug');

    var boundingSpheres = getBoundingSphereArrayScratch;
    var tmp = getBoundingSphereBoundingSphereScratch;

    var count = 0;
    var state = BoundingSphereState$1.DONE;
    var batches = this._batches;
    var batchesLength = batches.length;

    var id = entity.id;
    var updaters = this._updaterSets.get(id).updaters;

    for (var j = 0; j < updaters.length; j++) {
      var updater = updaters[j];
      for (var i = 0; i < batchesLength; i++) {
        state = batches[i].getBoundingSphere(updater, tmp);
        if (state === BoundingSphereState$1.PENDING) {
          return BoundingSphereState$1.PENDING;
        } else if (state === BoundingSphereState$1.DONE) {
          boundingSpheres[count] = BoundingSphere.clone(
            tmp,
            boundingSpheres[count]
          );
          count++;
        }
      }
    }

    if (count === 0) {
      return BoundingSphereState$1.FAILED;
    }

    boundingSpheres.length = count;
    BoundingSphere.fromBoundingSpheres(boundingSpheres, result);
    return BoundingSphereState$1.DONE;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  GeometryVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  GeometryVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      GeometryVisualizer.prototype._onCollectionChanged,
      this
    );
    this._addedObjects.removeAll();
    this._removedObjects.removeAll();

    var i;
    var batches = this._batches;
    var length = batches.length;
    for (i = 0; i < length; i++) {
      batches[i].removeAllPrimitives();
    }

    var subscriptions = this._subscriptions.values;
    length = subscriptions.length;
    for (i = 0; i < length; i++) {
      subscriptions[i]();
    }
    this._subscriptions.removeAll();

    var updaterSets = this._updaterSets.values;
    length = updaterSets.length;
    for (i = 0; i < length; i++) {
      updaterSets[i].destroy();
    }
    this._updaterSets.removeAll();
    return destroyObject(this);
  };

  /**
   * @private
   */
  GeometryVisualizer.prototype._removeUpdater = function (updater) {
    //We don't keep track of which batch an updater is in, so just remove it from all of them.
    var batches = this._batches;
    var length = batches.length;
    for (var i = 0; i < length; i++) {
      batches[i].remove(updater);
    }
  };

  /**
   * @private
   */
  GeometryVisualizer.prototype._insertUpdaterIntoBatch = function (
    time,
    updater
  ) {
    if (updater.isDynamic) {
      this._dynamicBatch.add(time, updater);
      return;
    }

    var shadows;
    if (updater.outlineEnabled || updater.fillEnabled) {
      shadows = updater.shadowsProperty.getValue(time);
    }

    var numberOfShadowModes = ShadowMode$1.NUMBER_OF_SHADOW_MODES;
    if (updater.outlineEnabled) {
      if (defined(updater.terrainOffsetProperty)) {
        this._outlineBatches[numberOfShadowModes + shadows].add(time, updater);
      } else {
        this._outlineBatches[shadows].add(time, updater);
      }
    }

    if (updater.fillEnabled) {
      if (updater.onTerrain) {
        var classificationType = updater.classificationTypeProperty.getValue(
          time
        );
        if (updater.fillMaterialProperty instanceof ColorMaterialProperty) {
          this._groundColorBatches[classificationType].add(time, updater);
        } else {
          // If unsupported, updater will not be on terrain.
          this._groundMaterialBatches[classificationType].add(time, updater);
        }
      } else if (updater.isClosed) {
        if (updater.fillMaterialProperty instanceof ColorMaterialProperty) {
          if (defined(updater.terrainOffsetProperty)) {
            this._closedColorBatches[numberOfShadowModes + shadows].add(
              time,
              updater
            );
          } else {
            this._closedColorBatches[shadows].add(time, updater);
          }
        } else if (defined(updater.terrainOffsetProperty)) {
          this._closedMaterialBatches[numberOfShadowModes + shadows].add(
            time,
            updater
          );
        } else {
          this._closedMaterialBatches[shadows].add(time, updater);
        }
      } else if (updater.fillMaterialProperty instanceof ColorMaterialProperty) {
        if (defined(updater.terrainOffsetProperty)) {
          this._openColorBatches[numberOfShadowModes + shadows].add(
            time,
            updater
          );
        } else {
          this._openColorBatches[shadows].add(time, updater);
        }
      } else if (defined(updater.terrainOffsetProperty)) {
        this._openMaterialBatches[numberOfShadowModes + shadows].add(
          time,
          updater
        );
      } else {
        this._openMaterialBatches[shadows].add(time, updater);
      }
    }
  };

  /**
   * @private
   */
  GeometryVisualizer._onGeometryChanged = function (updater) {
    var removedObjects = this._removedObjects;
    var changedObjects = this._changedObjects;

    var entity = updater.entity;
    var id = entity.id;

    if (!defined(removedObjects.get(id)) && !defined(changedObjects.get(id))) {
      changedObjects.set(id, entity);
    }
  };

  /**
   * @private
   */
  GeometryVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed
  ) {
    var addedObjects = this._addedObjects;
    var removedObjects = this._removedObjects;
    var changedObjects = this._changedObjects;

    var i;
    var id;
    var entity;
    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      id = entity.id;
      if (!addedObjects.remove(id)) {
        removedObjects.set(id, entity);
        changedObjects.remove(id);
      }
    }

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      id = entity.id;
      if (removedObjects.remove(id)) {
        changedObjects.set(id, entity);
      } else {
        addedObjects.set(id, entity);
      }
    }
  };

  var defaultScale$2 = 1.0;
  var defaultFont = "30px sans-serif";
  var defaultStyle = LabelStyle$1.FILL;
  var defaultFillColor = Color.WHITE;
  var defaultOutlineColor$2 = Color.BLACK;
  var defaultOutlineWidth$1 = 1.0;
  var defaultShowBackground = false;
  var defaultBackgroundColor$1 = new Color(0.165, 0.165, 0.165, 0.8);
  var defaultBackgroundPadding$1 = new Cartesian2(7, 5);
  var defaultPixelOffset$1 = Cartesian2.ZERO;
  var defaultEyeOffset$1 = Cartesian3.ZERO;
  var defaultHeightReference$1 = HeightReference$1.NONE;
  var defaultHorizontalOrigin$1 = HorizontalOrigin$1.CENTER;
  var defaultVerticalOrigin$1 = VerticalOrigin$1.CENTER;

  var positionScratch$a = new Cartesian3();
  var fillColorScratch = new Color();
  var outlineColorScratch = new Color();
  var backgroundColorScratch = new Color();
  var backgroundPaddingScratch = new Cartesian2();
  var eyeOffsetScratch$1 = new Cartesian3();
  var pixelOffsetScratch$1 = new Cartesian2();
  var translucencyByDistanceScratch$1 = new NearFarScalar();
  var pixelOffsetScaleByDistanceScratch$1 = new NearFarScalar();
  var scaleByDistanceScratch$1 = new NearFarScalar();
  var distanceDisplayConditionScratch$6 = new DistanceDisplayCondition();

  function EntityData$1(entity) {
    this.entity = entity;
    this.label = undefined;
    this.index = undefined;
  }

  /**
   * A {@link Visualizer} which maps the {@link LabelGraphics} instance
   * in {@link Entity#label} to a {@link Label}.
   * @alias LabelVisualizer
   * @constructor
   *
   * @param {EntityCluster} entityCluster The entity cluster to manage the collection of billboards and optionally cluster with other entities.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   */
  function LabelVisualizer(entityCluster, entityCollection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entityCluster)) {
      throw new DeveloperError("entityCluster is required.");
    }
    if (!defined(entityCollection)) {
      throw new DeveloperError("entityCollection is required.");
    }
    //>>includeEnd('debug');

    entityCollection.collectionChanged.addEventListener(
      LabelVisualizer.prototype._onCollectionChanged,
      this
    );

    this._cluster = entityCluster;
    this._entityCollection = entityCollection;
    this._items = new AssociativeArray();

    this._onCollectionChanged(entityCollection, entityCollection.values, [], []);
  }

  /**
   * Updates the primitives created by this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} This function always returns true.
   */
  LabelVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var items = this._items.values;
    var cluster = this._cluster;

    for (var i = 0, len = items.length; i < len; i++) {
      var item = items[i];
      var entity = item.entity;
      var labelGraphics = entity._label;
      var text;
      var label = item.label;
      var show =
        entity.isShowing &&
        entity.isAvailable(time) &&
        Property.getValueOrDefault(labelGraphics._show, time, true);
      var position;
      if (show) {
        position = Property.getValueOrUndefined(
          entity._position,
          time,
          positionScratch$a
        );
        text = Property.getValueOrUndefined(labelGraphics._text, time);
        show = defined(position) && defined(text);
      }

      if (!show) {
        //don't bother creating or updating anything else
        returnPrimitive$1(item, entity, cluster);
        continue;
      }

      if (!Property.isConstant(entity._position)) {
        cluster._clusterDirty = true;
      }

      var updateClamping = false;
      var heightReference = Property.getValueOrDefault(
        labelGraphics._heightReference,
        time,
        defaultHeightReference$1
      );

      if (!defined(label)) {
        label = cluster.getLabel(entity);
        label.id = entity;
        item.label = label;

        // If this new label happens to have a position and height reference that match our new values,
        // label._updateClamping will not be called automatically. That's a problem because the clamped
        // height may be based on different terrain than is now loaded. So we'll manually call
        // _updateClamping below.
        updateClamping =
          Cartesian3.equals(label.position, position) &&
          label.heightReference === heightReference;
      }

      label.show = true;
      label.position = position;
      label.text = text;
      label.scale = Property.getValueOrDefault(
        labelGraphics._scale,
        time,
        defaultScale$2
      );
      label.font = Property.getValueOrDefault(
        labelGraphics._font,
        time,
        defaultFont
      );
      label.style = Property.getValueOrDefault(
        labelGraphics._style,
        time,
        defaultStyle
      );
      label.fillColor = Property.getValueOrDefault(
        labelGraphics._fillColor,
        time,
        defaultFillColor,
        fillColorScratch
      );
      label.outlineColor = Property.getValueOrDefault(
        labelGraphics._outlineColor,
        time,
        defaultOutlineColor$2,
        outlineColorScratch
      );
      label.outlineWidth = Property.getValueOrDefault(
        labelGraphics._outlineWidth,
        time,
        defaultOutlineWidth$1
      );
      label.showBackground = Property.getValueOrDefault(
        labelGraphics._showBackground,
        time,
        defaultShowBackground
      );
      label.backgroundColor = Property.getValueOrDefault(
        labelGraphics._backgroundColor,
        time,
        defaultBackgroundColor$1,
        backgroundColorScratch
      );
      label.backgroundPadding = Property.getValueOrDefault(
        labelGraphics._backgroundPadding,
        time,
        defaultBackgroundPadding$1,
        backgroundPaddingScratch
      );
      label.pixelOffset = Property.getValueOrDefault(
        labelGraphics._pixelOffset,
        time,
        defaultPixelOffset$1,
        pixelOffsetScratch$1
      );
      label.eyeOffset = Property.getValueOrDefault(
        labelGraphics._eyeOffset,
        time,
        defaultEyeOffset$1,
        eyeOffsetScratch$1
      );
      label.heightReference = heightReference;
      label.horizontalOrigin = Property.getValueOrDefault(
        labelGraphics._horizontalOrigin,
        time,
        defaultHorizontalOrigin$1
      );
      label.verticalOrigin = Property.getValueOrDefault(
        labelGraphics._verticalOrigin,
        time,
        defaultVerticalOrigin$1
      );
      label.translucencyByDistance = Property.getValueOrUndefined(
        labelGraphics._translucencyByDistance,
        time,
        translucencyByDistanceScratch$1
      );
      label.pixelOffsetScaleByDistance = Property.getValueOrUndefined(
        labelGraphics._pixelOffsetScaleByDistance,
        time,
        pixelOffsetScaleByDistanceScratch$1
      );
      label.scaleByDistance = Property.getValueOrUndefined(
        labelGraphics._scaleByDistance,
        time,
        scaleByDistanceScratch$1
      );
      label.distanceDisplayCondition = Property.getValueOrUndefined(
        labelGraphics._distanceDisplayCondition,
        time,
        distanceDisplayConditionScratch$6
      );
      label.disableDepthTestDistance = Property.getValueOrUndefined(
        labelGraphics._disableDepthTestDistance,
        time
      );

      if (updateClamping) {
        label._updateClamping();
      }
    }
    return true;
  };

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  LabelVisualizer.prototype.getBoundingSphere = function (entity, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var item = this._items.get(entity.id);
    if (!defined(item) || !defined(item.label)) {
      return BoundingSphereState$1.FAILED;
    }

    var label = item.label;
    result.center = Cartesian3.clone(
      defaultValue(label._clampedPosition, label.position),
      result.center
    );
    result.radius = 0;
    return BoundingSphereState$1.DONE;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  LabelVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  LabelVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      LabelVisualizer.prototype._onCollectionChanged,
      this
    );
    var entities = this._entityCollection.values;
    for (var i = 0; i < entities.length; i++) {
      this._cluster.removeLabel(entities[i]);
    }
    return destroyObject(this);
  };

  LabelVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed,
    changed
  ) {
    var i;
    var entity;
    var items = this._items;
    var cluster = this._cluster;

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      if (defined(entity._label) && defined(entity._position)) {
        items.set(entity.id, new EntityData$1(entity));
      }
    }

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      if (defined(entity._label) && defined(entity._position)) {
        if (!items.contains(entity.id)) {
          items.set(entity.id, new EntityData$1(entity));
        }
      } else {
        returnPrimitive$1(items.get(entity.id), entity, cluster);
        items.remove(entity.id);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      returnPrimitive$1(items.get(entity.id), entity, cluster);
      items.remove(entity.id);
    }
  };

  function returnPrimitive$1(item, entity, cluster) {
    if (defined(item)) {
      item.label = undefined;
      cluster.removeLabel(entity);
    }
  }

  var defaultScale$3 = 1.0;
  var defaultMinimumPixelSize = 0.0;
  var defaultIncrementallyLoadTextures = true;
  var defaultClampAnimations = true;
  var defaultShadows$1 = ShadowMode$1.ENABLED;
  var defaultHeightReference$2 = HeightReference$1.NONE;
  var defaultSilhouetteColor = Color.RED;
  var defaultSilhouetteSize = 0.0;
  var defaultColor$6 = Color.WHITE;
  var defaultColorBlendMode = ColorBlendMode$1.HIGHLIGHT;
  var defaultColorBlendAmount = 0.5;
  var defaultImageBasedLightingFactor = new Cartesian2(1.0, 1.0);

  var modelMatrixScratch$1 = new Matrix4();
  var nodeMatrixScratch = new Matrix4();

  /**
   * A {@link Visualizer} which maps {@link Entity#model} to a {@link Model}.
   * @alias ModelVisualizer
   * @constructor
   *
   * @param {Scene} scene The scene the primitives will be rendered in.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   */
  function ModelVisualizer(scene, entityCollection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    if (!defined(entityCollection)) {
      throw new DeveloperError("entityCollection is required.");
    }
    //>>includeEnd('debug');

    entityCollection.collectionChanged.addEventListener(
      ModelVisualizer.prototype._onCollectionChanged,
      this
    );

    this._scene = scene;
    this._primitives = scene.primitives;
    this._entityCollection = entityCollection;
    this._modelHash = {};
    this._entitiesToVisualize = new AssociativeArray();
    this._onCollectionChanged(entityCollection, entityCollection.values, [], []);
  }

  /**
   * Updates models created this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} This function always returns true.
   */
  ModelVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var entities = this._entitiesToVisualize.values;
    var modelHash = this._modelHash;
    var primitives = this._primitives;

    for (var i = 0, len = entities.length; i < len; i++) {
      var entity = entities[i];
      var modelGraphics = entity._model;

      var resource;
      var modelData = modelHash[entity.id];
      var show =
        entity.isShowing &&
        entity.isAvailable(time) &&
        Property.getValueOrDefault(modelGraphics._show, time, true);

      var modelMatrix;
      if (show) {
        modelMatrix = entity.computeModelMatrix(time, modelMatrixScratch$1);
        resource = Resource.createIfNeeded(
          Property.getValueOrUndefined(modelGraphics._uri, time)
        );
        show = defined(modelMatrix) && defined(resource);
      }

      if (!show) {
        if (defined(modelData)) {
          modelData.modelPrimitive.show = false;
        }
        continue;
      }

      var model = defined(modelData) ? modelData.modelPrimitive : undefined;
      if (!defined(model) || resource.url !== modelData.url) {
        if (defined(model)) {
          primitives.removeAndDestroy(model);
          delete modelHash[entity.id];
        }
        model = Model.fromGltf({
          url: resource,
          incrementallyLoadTextures: Property.getValueOrDefault(
            modelGraphics._incrementallyLoadTextures,
            time,
            defaultIncrementallyLoadTextures
          ),
          scene: this._scene,
        });
        model.id = entity;
        primitives.add(model);

        modelData = {
          modelPrimitive: model,
          url: resource.url,
          animationsRunning: false,
          nodeTransformationsScratch: {},
          articulationsScratch: {},
          loadFail: false,
        };
        modelHash[entity.id] = modelData;

        checkModelLoad(model, entity, modelHash);
      }

      model.show = true;
      model.scale = Property.getValueOrDefault(
        modelGraphics._scale,
        time,
        defaultScale$3
      );
      model.minimumPixelSize = Property.getValueOrDefault(
        modelGraphics._minimumPixelSize,
        time,
        defaultMinimumPixelSize
      );
      model.maximumScale = Property.getValueOrUndefined(
        modelGraphics._maximumScale,
        time
      );
      model.modelMatrix = Matrix4.clone(modelMatrix, model.modelMatrix);
      model.shadows = Property.getValueOrDefault(
        modelGraphics._shadows,
        time,
        defaultShadows$1
      );
      model.heightReference = Property.getValueOrDefault(
        modelGraphics._heightReference,
        time,
        defaultHeightReference$2
      );
      model.distanceDisplayCondition = Property.getValueOrUndefined(
        modelGraphics._distanceDisplayCondition,
        time
      );
      model.silhouetteColor = Property.getValueOrDefault(
        modelGraphics._silhouetteColor,
        time,
        defaultSilhouetteColor,
        model._silhouetteColor
      );
      model.silhouetteSize = Property.getValueOrDefault(
        modelGraphics._silhouetteSize,
        time,
        defaultSilhouetteSize
      );
      model.color = Property.getValueOrDefault(
        modelGraphics._color,
        time,
        defaultColor$6,
        model._color
      );
      model.colorBlendMode = Property.getValueOrDefault(
        modelGraphics._colorBlendMode,
        time,
        defaultColorBlendMode
      );
      model.colorBlendAmount = Property.getValueOrDefault(
        modelGraphics._colorBlendAmount,
        time,
        defaultColorBlendAmount
      );
      model.clippingPlanes = Property.getValueOrUndefined(
        modelGraphics._clippingPlanes,
        time
      );
      model.clampAnimations = Property.getValueOrDefault(
        modelGraphics._clampAnimations,
        time,
        defaultClampAnimations
      );
      model.imageBasedLightingFactor = Property.getValueOrDefault(
        modelGraphics._imageBasedLightingFactor,
        time,
        defaultImageBasedLightingFactor
      );
      model.lightColor = Property.getValueOrUndefined(
        modelGraphics._lightColor,
        time
      );

      if (model.ready) {
        var runAnimations = Property.getValueOrDefault(
          modelGraphics._runAnimations,
          time,
          true
        );
        if (modelData.animationsRunning !== runAnimations) {
          if (runAnimations) {
            model.activeAnimations.addAll({
              loop: ModelAnimationLoop$1.REPEAT,
            });
          } else {
            model.activeAnimations.removeAll();
          }
          modelData.animationsRunning = runAnimations;
        }

        // Apply node transformations
        var nodeTransformations = Property.getValueOrUndefined(
          modelGraphics._nodeTransformations,
          time,
          modelData.nodeTransformationsScratch
        );
        if (defined(nodeTransformations)) {
          var nodeNames = Object.keys(nodeTransformations);
          for (
            var nodeIndex = 0, nodeLength = nodeNames.length;
            nodeIndex < nodeLength;
            ++nodeIndex
          ) {
            var nodeName = nodeNames[nodeIndex];

            var nodeTransformation = nodeTransformations[nodeName];
            if (!defined(nodeTransformation)) {
              continue;
            }

            var modelNode = model.getNode(nodeName);
            if (!defined(modelNode)) {
              continue;
            }

            var transformationMatrix = Matrix4.fromTranslationRotationScale(
              nodeTransformation,
              nodeMatrixScratch
            );
            modelNode.matrix = Matrix4.multiply(
              modelNode.originalMatrix,
              transformationMatrix,
              transformationMatrix
            );
          }
        }

        // Apply articulations
        var anyArticulationUpdated = false;
        var articulations = Property.getValueOrUndefined(
          modelGraphics._articulations,
          time,
          modelData.articulationsScratch
        );
        if (defined(articulations)) {
          var articulationStageKeys = Object.keys(articulations);
          for (
            var s = 0, numKeys = articulationStageKeys.length;
            s < numKeys;
            ++s
          ) {
            var key = articulationStageKeys[s];

            var articulationStageValue = articulations[key];
            if (!defined(articulationStageValue)) {
              continue;
            }

            anyArticulationUpdated = true;
            model.setArticulationStage(key, articulationStageValue);
          }
        }

        if (anyArticulationUpdated) {
          model.applyArticulations();
        }
      }
    }

    return true;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  ModelVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  ModelVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      ModelVisualizer.prototype._onCollectionChanged,
      this
    );
    var entities = this._entitiesToVisualize.values;
    var modelHash = this._modelHash;
    var primitives = this._primitives;
    for (var i = entities.length - 1; i > -1; i--) {
      removeModel(this, entities[i], modelHash, primitives);
    }
    return destroyObject(this);
  };

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  ModelVisualizer.prototype.getBoundingSphere = function (entity, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var modelData = this._modelHash[entity.id];
    if (!defined(modelData) || modelData.loadFail) {
      return BoundingSphereState$1.FAILED;
    }

    var model = modelData.modelPrimitive;
    if (!defined(model) || !model.show) {
      return BoundingSphereState$1.FAILED;
    }

    if (!model.ready) {
      return BoundingSphereState$1.PENDING;
    }

    if (model.heightReference === HeightReference$1.NONE) {
      BoundingSphere.transform(model.boundingSphere, model.modelMatrix, result);
    } else {
      if (!defined(model._clampedModelMatrix)) {
        return BoundingSphereState$1.PENDING;
      }
      BoundingSphere.transform(
        model.boundingSphere,
        model._clampedModelMatrix,
        result
      );
    }
    return BoundingSphereState$1.DONE;
  };

  /**
   * @private
   */
  ModelVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed,
    changed
  ) {
    var i;
    var entity;
    var entities = this._entitiesToVisualize;
    var modelHash = this._modelHash;
    var primitives = this._primitives;

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      if (defined(entity._model) && defined(entity._position)) {
        entities.set(entity.id, entity);
      }
    }

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      if (defined(entity._model) && defined(entity._position)) {
        clearNodeTransformationsArticulationsScratch(entity, modelHash);
        entities.set(entity.id, entity);
      } else {
        removeModel(this, entity, modelHash, primitives);
        entities.remove(entity.id);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      removeModel(this, entity, modelHash, primitives);
      entities.remove(entity.id);
    }
  };

  function removeModel(visualizer, entity, modelHash, primitives) {
    var modelData = modelHash[entity.id];
    if (defined(modelData)) {
      primitives.removeAndDestroy(modelData.modelPrimitive);
      delete modelHash[entity.id];
    }
  }

  function clearNodeTransformationsArticulationsScratch(entity, modelHash) {
    var modelData = modelHash[entity.id];
    if (defined(modelData)) {
      modelData.nodeTransformationsScratch = {};
      modelData.articulationsScratch = {};
    }
  }

  function checkModelLoad(model, entity, modelHash) {
    model.readyPromise.otherwise(function (error) {
      console.error(error);
      modelHash[entity.id].loadFail = true;
    });
  }

  /**
   * This is a temporary class for scaling position properties to the WGS84 surface.
   * It will go away or be refactored to support data with arbitrary height references.
   * @private
   */
  function ScaledPositionProperty(value) {
    this._definitionChanged = new Event();
    this._value = undefined;
    this._removeSubscription = undefined;
    this.setValue(value);
  }

  Object.defineProperties(ScaledPositionProperty.prototype, {
    isConstant: {
      get: function () {
        return Property.isConstant(this._value);
      },
    },
    definitionChanged: {
      get: function () {
        return this._definitionChanged;
      },
    },
    referenceFrame: {
      get: function () {
        return defined(this._value)
          ? this._value.referenceFrame
          : ReferenceFrame$1.FIXED;
      },
    },
  });

  ScaledPositionProperty.prototype.getValue = function (time, result) {
    return this.getValueInReferenceFrame(time, ReferenceFrame$1.FIXED, result);
  };

  ScaledPositionProperty.prototype.setValue = function (value) {
    if (this._value !== value) {
      this._value = value;

      if (defined(this._removeSubscription)) {
        this._removeSubscription();
        this._removeSubscription = undefined;
      }

      if (defined(value)) {
        this._removeSubscription = value.definitionChanged.addEventListener(
          this._raiseDefinitionChanged,
          this
        );
      }
      this._definitionChanged.raiseEvent(this);
    }
  };

  ScaledPositionProperty.prototype.getValueInReferenceFrame = function (
    time,
    referenceFrame,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    if (!defined(referenceFrame)) {
      throw new DeveloperError("referenceFrame is required.");
    }
    //>>includeEnd('debug');

    if (!defined(this._value)) {
      return undefined;
    }

    result = this._value.getValueInReferenceFrame(time, referenceFrame, result);
    return defined(result)
      ? Ellipsoid.WGS84.scaleToGeodeticSurface(result, result)
      : undefined;
  };

  ScaledPositionProperty.prototype.equals = function (other) {
    return (
      this === other ||
      (other instanceof ScaledPositionProperty && this._value === other._value)
    );
  };

  ScaledPositionProperty.prototype._raiseDefinitionChanged = function () {
    this._definitionChanged.raiseEvent(this);
  };

  var defaultResolution = 60.0;
  var defaultWidth = 1.0;

  var scratchTimeInterval$1 = new TimeInterval();
  var subSampleCompositePropertyScratch = new TimeInterval();
  var subSampleIntervalPropertyScratch = new TimeInterval();

  function EntityData$2(entity) {
    this.entity = entity;
    this.polyline = undefined;
    this.index = undefined;
    this.updater = undefined;
  }

  function subSampleSampledProperty(
    property,
    start,
    stop,
    times,
    updateTime,
    referenceFrame,
    maximumStep,
    startingIndex,
    result
  ) {
    var r = startingIndex;
    //Always step exactly on start (but only use it if it exists.)
    var tmp;
    tmp = property.getValueInReferenceFrame(start, referenceFrame, result[r]);
    if (defined(tmp)) {
      result[r++] = tmp;
    }

    var steppedOnNow =
      !defined(updateTime) ||
      JulianDate.lessThanOrEquals(updateTime, start) ||
      JulianDate.greaterThanOrEquals(updateTime, stop);

    //Iterate over all interval times and add the ones that fall in our
    //time range.  Note that times can contain data outside of
    //the intervals range.  This is by design for use with interpolation.
    var t = 0;
    var len = times.length;
    var current = times[t];
    var loopStop = stop;
    var sampling = false;
    var sampleStepsToTake;
    var sampleStepsTaken;
    var sampleStepSize;

    while (t < len) {
      if (!steppedOnNow && JulianDate.greaterThanOrEquals(current, updateTime)) {
        tmp = property.getValueInReferenceFrame(
          updateTime,
          referenceFrame,
          result[r]
        );
        if (defined(tmp)) {
          result[r++] = tmp;
        }
        steppedOnNow = true;
      }
      if (
        JulianDate.greaterThan(current, start) &&
        JulianDate.lessThan(current, loopStop) &&
        !current.equals(updateTime)
      ) {
        tmp = property.getValueInReferenceFrame(
          current,
          referenceFrame,
          result[r]
        );
        if (defined(tmp)) {
          result[r++] = tmp;
        }
      }

      if (t < len - 1) {
        if (maximumStep > 0 && !sampling) {
          var next = times[t + 1];
          var secondsUntilNext = JulianDate.secondsDifference(next, current);
          sampling = secondsUntilNext > maximumStep;

          if (sampling) {
            sampleStepsToTake = Math.ceil(secondsUntilNext / maximumStep);
            sampleStepsTaken = 0;
            sampleStepSize = secondsUntilNext / Math.max(sampleStepsToTake, 2);
            sampleStepsToTake = Math.max(sampleStepsToTake - 1, 1);
          }
        }

        if (sampling && sampleStepsTaken < sampleStepsToTake) {
          current = JulianDate.addSeconds(
            current,
            sampleStepSize,
            new JulianDate()
          );
          sampleStepsTaken++;
          continue;
        }
      }
      sampling = false;
      t++;
      current = times[t];
    }

    //Always step exactly on stop (but only use it if it exists.)
    tmp = property.getValueInReferenceFrame(stop, referenceFrame, result[r]);
    if (defined(tmp)) {
      result[r++] = tmp;
    }

    return r;
  }

  function subSampleGenericProperty(
    property,
    start,
    stop,
    updateTime,
    referenceFrame,
    maximumStep,
    startingIndex,
    result
  ) {
    var tmp;
    var i = 0;
    var index = startingIndex;
    var time = start;
    var stepSize = Math.max(maximumStep, 60);
    var steppedOnNow =
      !defined(updateTime) ||
      JulianDate.lessThanOrEquals(updateTime, start) ||
      JulianDate.greaterThanOrEquals(updateTime, stop);
    while (JulianDate.lessThan(time, stop)) {
      if (!steppedOnNow && JulianDate.greaterThanOrEquals(time, updateTime)) {
        steppedOnNow = true;
        tmp = property.getValueInReferenceFrame(
          updateTime,
          referenceFrame,
          result[index]
        );
        if (defined(tmp)) {
          result[index] = tmp;
          index++;
        }
      }
      tmp = property.getValueInReferenceFrame(
        time,
        referenceFrame,
        result[index]
      );
      if (defined(tmp)) {
        result[index] = tmp;
        index++;
      }
      i++;
      time = JulianDate.addSeconds(start, stepSize * i, new JulianDate());
    }
    //Always sample stop.
    tmp = property.getValueInReferenceFrame(stop, referenceFrame, result[index]);
    if (defined(tmp)) {
      result[index] = tmp;
      index++;
    }
    return index;
  }

  function subSampleIntervalProperty(
    property,
    start,
    stop,
    updateTime,
    referenceFrame,
    maximumStep,
    startingIndex,
    result
  ) {
    subSampleIntervalPropertyScratch.start = start;
    subSampleIntervalPropertyScratch.stop = stop;

    var index = startingIndex;
    var intervals = property.intervals;
    for (var i = 0; i < intervals.length; i++) {
      var interval = intervals.get(i);
      if (
        !TimeInterval.intersect(
          interval,
          subSampleIntervalPropertyScratch,
          scratchTimeInterval$1
        ).isEmpty
      ) {
        var time = interval.start;
        if (!interval.isStartIncluded) {
          if (interval.isStopIncluded) {
            time = interval.stop;
          } else {
            time = JulianDate.addSeconds(
              interval.start,
              JulianDate.secondsDifference(interval.stop, interval.start) / 2,
              new JulianDate()
            );
          }
        }
        var tmp = property.getValueInReferenceFrame(
          time,
          referenceFrame,
          result[index]
        );
        if (defined(tmp)) {
          result[index] = tmp;
          index++;
        }
      }
    }
    return index;
  }

  function subSampleConstantProperty(
    property,
    start,
    stop,
    updateTime,
    referenceFrame,
    maximumStep,
    startingIndex,
    result
  ) {
    var tmp = property.getValueInReferenceFrame(
      start,
      referenceFrame,
      result[startingIndex]
    );
    if (defined(tmp)) {
      result[startingIndex++] = tmp;
    }
    return startingIndex;
  }

  function subSampleCompositeProperty(
    property,
    start,
    stop,
    updateTime,
    referenceFrame,
    maximumStep,
    startingIndex,
    result
  ) {
    subSampleCompositePropertyScratch.start = start;
    subSampleCompositePropertyScratch.stop = stop;

    var index = startingIndex;
    var intervals = property.intervals;
    for (var i = 0; i < intervals.length; i++) {
      var interval = intervals.get(i);
      if (
        !TimeInterval.intersect(
          interval,
          subSampleCompositePropertyScratch,
          scratchTimeInterval$1
        ).isEmpty
      ) {
        var intervalStart = interval.start;
        var intervalStop = interval.stop;

        var sampleStart = start;
        if (JulianDate.greaterThan(intervalStart, sampleStart)) {
          sampleStart = intervalStart;
        }

        var sampleStop = stop;
        if (JulianDate.lessThan(intervalStop, sampleStop)) {
          sampleStop = intervalStop;
        }

        index = reallySubSample(
          interval.data,
          sampleStart,
          sampleStop,
          updateTime,
          referenceFrame,
          maximumStep,
          index,
          result
        );
      }
    }
    return index;
  }

  function reallySubSample(
    property,
    start,
    stop,
    updateTime,
    referenceFrame,
    maximumStep,
    index,
    result
  ) {
    //Unwrap any references until we have the actual property.
    while (property instanceof ReferenceProperty) {
      property = property.resolvedProperty;
    }

    if (property instanceof SampledPositionProperty) {
      var times = property._property._times;
      index = subSampleSampledProperty(
        property,
        start,
        stop,
        times,
        updateTime,
        referenceFrame,
        maximumStep,
        index,
        result
      );
    } else if (property instanceof CompositePositionProperty) {
      index = subSampleCompositeProperty(
        property,
        start,
        stop,
        updateTime,
        referenceFrame,
        maximumStep,
        index,
        result
      );
    } else if (property instanceof TimeIntervalCollectionPositionProperty) {
      index = subSampleIntervalProperty(
        property,
        start,
        stop,
        updateTime,
        referenceFrame,
        maximumStep,
        index,
        result
      );
    } else if (
      property instanceof ConstantPositionProperty ||
      (property instanceof ScaledPositionProperty &&
        Property.isConstant(property))
    ) {
      index = subSampleConstantProperty(
        property,
        start,
        stop,
        updateTime,
        referenceFrame,
        maximumStep,
        index,
        result
      );
    } else {
      //Fallback to generic sampling.
      index = subSampleGenericProperty(
        property,
        start,
        stop,
        updateTime,
        referenceFrame,
        maximumStep,
        index,
        result
      );
    }
    return index;
  }

  function subSample(
    property,
    start,
    stop,
    updateTime,
    referenceFrame,
    maximumStep,
    result
  ) {
    if (!defined(result)) {
      result = [];
    }

    var length = reallySubSample(
      property,
      start,
      stop,
      updateTime,
      referenceFrame,
      maximumStep,
      0,
      result
    );
    result.length = length;
    return result;
  }

  var toFixedScratch = new Matrix3();
  function PolylineUpdater(scene, referenceFrame) {
    this._unusedIndexes = [];
    this._polylineCollection = new PolylineCollection();
    this._scene = scene;
    this._referenceFrame = referenceFrame;
    scene.primitives.add(this._polylineCollection);
  }

  PolylineUpdater.prototype.update = function (time) {
    if (this._referenceFrame === ReferenceFrame$1.INERTIAL) {
      var toFixed = Transforms.computeIcrfToFixedMatrix(time, toFixedScratch);
      if (!defined(toFixed)) {
        toFixed = Transforms.computeTemeToPseudoFixedMatrix(time, toFixedScratch);
      }
      Matrix4.fromRotationTranslation(
        toFixed,
        Cartesian3.ZERO,
        this._polylineCollection.modelMatrix
      );
    }
  };

  PolylineUpdater.prototype.updateObject = function (time, item) {
    var entity = item.entity;
    var pathGraphics = entity._path;
    var positionProperty = entity._position;

    var sampleStart;
    var sampleStop;
    var showProperty = pathGraphics._show;
    var polyline = item.polyline;
    var show =
      entity.isShowing && (!defined(showProperty) || showProperty.getValue(time));

    //While we want to show the path, there may not actually be anything to show
    //depending on lead/trail settings.  Compute the interval of the path to
    //show and check against actual availability.
    if (show) {
      var leadTime = Property.getValueOrUndefined(pathGraphics._leadTime, time);
      var trailTime = Property.getValueOrUndefined(pathGraphics._trailTime, time);
      var availability = entity._availability;
      var hasAvailability = defined(availability);
      var hasLeadTime = defined(leadTime);
      var hasTrailTime = defined(trailTime);

      //Objects need to have either defined availability or both a lead and trail time in order to
      //draw a path (since we can't draw "infinite" paths.
      show = hasAvailability || (hasLeadTime && hasTrailTime);

      //The final step is to compute the actual start/stop times of the path to show.
      //If current time is outside of the availability interval, there's a chance that
      //we won't have to draw anything anyway.
      if (show) {
        if (hasTrailTime) {
          sampleStart = JulianDate.addSeconds(time, -trailTime, new JulianDate());
        }
        if (hasLeadTime) {
          sampleStop = JulianDate.addSeconds(time, leadTime, new JulianDate());
        }

        if (hasAvailability) {
          var start = availability.start;
          var stop = availability.stop;

          if (!hasTrailTime || JulianDate.greaterThan(start, sampleStart)) {
            sampleStart = start;
          }

          if (!hasLeadTime || JulianDate.lessThan(stop, sampleStop)) {
            sampleStop = stop;
          }
        }
        show = JulianDate.lessThan(sampleStart, sampleStop);
      }
    }

    if (!show) {
      //don't bother creating or updating anything else
      if (defined(polyline)) {
        this._unusedIndexes.push(item.index);
        item.polyline = undefined;
        polyline.show = false;
        item.index = undefined;
      }
      return;
    }

    if (!defined(polyline)) {
      var unusedIndexes = this._unusedIndexes;
      var length = unusedIndexes.length;
      if (length > 0) {
        var index = unusedIndexes.pop();
        polyline = this._polylineCollection.get(index);
        item.index = index;
      } else {
        item.index = this._polylineCollection.length;
        polyline = this._polylineCollection.add();
      }
      polyline.id = entity;
      item.polyline = polyline;
    }

    var resolution = Property.getValueOrDefault(
      pathGraphics._resolution,
      time,
      defaultResolution
    );

    polyline.show = true;
    polyline.positions = subSample(
      positionProperty,
      sampleStart,
      sampleStop,
      time,
      this._referenceFrame,
      resolution,
      polyline.positions.slice()
    );
    polyline.material = MaterialProperty.getValue(
      time,
      pathGraphics._material,
      polyline.material
    );
    polyline.width = Property.getValueOrDefault(
      pathGraphics._width,
      time,
      defaultWidth
    );
    polyline.distanceDisplayCondition = Property.getValueOrUndefined(
      pathGraphics._distanceDisplayCondition,
      time,
      polyline.distanceDisplayCondition
    );
  };

  PolylineUpdater.prototype.removeObject = function (item) {
    var polyline = item.polyline;
    if (defined(polyline)) {
      this._unusedIndexes.push(item.index);
      item.polyline = undefined;
      polyline.show = false;
      polyline.id = undefined;
      item.index = undefined;
    }
  };

  PolylineUpdater.prototype.destroy = function () {
    this._scene.primitives.remove(this._polylineCollection);
    return destroyObject(this);
  };

  /**
   * A {@link Visualizer} which maps {@link Entity#path} to a {@link Polyline}.
   * @alias PathVisualizer
   * @constructor
   *
   * @param {Scene} scene The scene the primitives will be rendered in.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   */
  function PathVisualizer(scene, entityCollection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    if (!defined(entityCollection)) {
      throw new DeveloperError("entityCollection is required.");
    }
    //>>includeEnd('debug');

    entityCollection.collectionChanged.addEventListener(
      PathVisualizer.prototype._onCollectionChanged,
      this
    );

    this._scene = scene;
    this._updaters = {};
    this._entityCollection = entityCollection;
    this._items = new AssociativeArray();

    this._onCollectionChanged(entityCollection, entityCollection.values, [], []);
  }

  /**
   * Updates all of the primitives created by this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} This function always returns true.
   */
  PathVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var updaters = this._updaters;
    for (var key in updaters) {
      if (updaters.hasOwnProperty(key)) {
        updaters[key].update(time);
      }
    }

    var items = this._items.values;
    if (
      items.length === 0 &&
      defined(this._updaters) &&
      Object.keys(this._updaters).length > 0
    ) {
      for (var u in updaters) {
        if (updaters.hasOwnProperty(u)) {
          updaters[u].destroy();
        }
      }
      this._updaters = {};
    }

    for (var i = 0, len = items.length; i < len; i++) {
      var item = items[i];
      var entity = item.entity;
      var positionProperty = entity._position;

      var lastUpdater = item.updater;

      var frameToVisualize = ReferenceFrame$1.FIXED;
      if (this._scene.mode === SceneMode$1.SCENE3D) {
        frameToVisualize = positionProperty.referenceFrame;
      }

      var currentUpdater = this._updaters[frameToVisualize];

      if (lastUpdater === currentUpdater && defined(currentUpdater)) {
        currentUpdater.updateObject(time, item);
        continue;
      }

      if (defined(lastUpdater)) {
        lastUpdater.removeObject(item);
      }

      if (!defined(currentUpdater)) {
        currentUpdater = new PolylineUpdater(this._scene, frameToVisualize);
        currentUpdater.update(time);
        this._updaters[frameToVisualize] = currentUpdater;
      }

      item.updater = currentUpdater;
      if (defined(currentUpdater)) {
        currentUpdater.updateObject(time, item);
      }
    }
    return true;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  PathVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  PathVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      PathVisualizer.prototype._onCollectionChanged,
      this
    );

    var updaters = this._updaters;
    for (var key in updaters) {
      if (updaters.hasOwnProperty(key)) {
        updaters[key].destroy();
      }
    }

    return destroyObject(this);
  };

  PathVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed,
    changed
  ) {
    var i;
    var entity;
    var item;
    var items = this._items;

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      if (defined(entity._path) && defined(entity._position)) {
        items.set(entity.id, new EntityData$2(entity));
      }
    }

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      if (defined(entity._path) && defined(entity._position)) {
        if (!items.contains(entity.id)) {
          items.set(entity.id, new EntityData$2(entity));
        }
      } else {
        item = items.get(entity.id);
        if (defined(item)) {
          if (defined(item.updater)) {
            item.updater.removeObject(item);
          }
          items.remove(entity.id);
        }
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      item = items.get(entity.id);
      if (defined(item)) {
        if (defined(item.updater)) {
          item.updater.removeObject(item);
        }
        items.remove(entity.id);
      }
    }
  };

  //for testing
  PathVisualizer._subSample = subSample;

  var defaultColor$7 = Color.WHITE;
  var defaultOutlineColor$3 = Color.BLACK;
  var defaultOutlineWidth$2 = 0.0;
  var defaultPixelSize = 1.0;
  var defaultDisableDepthTestDistance = 0.0;

  var colorScratch$6 = new Color();
  var positionScratch$b = new Cartesian3();
  var outlineColorScratch$1 = new Color();
  var scaleByDistanceScratch$2 = new NearFarScalar();
  var translucencyByDistanceScratch$2 = new NearFarScalar();
  var distanceDisplayConditionScratch$7 = new DistanceDisplayCondition();

  function EntityData$3(entity) {
    this.entity = entity;
    this.pointPrimitive = undefined;
    this.billboard = undefined;
    this.color = undefined;
    this.outlineColor = undefined;
    this.pixelSize = undefined;
    this.outlineWidth = undefined;
  }

  /**
   * A {@link Visualizer} which maps {@link Entity#point} to a {@link PointPrimitive}.
   * @alias PointVisualizer
   * @constructor
   *
   * @param {EntityCluster} entityCluster The entity cluster to manage the collection of billboards and optionally cluster with other entities.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   */
  function PointVisualizer(entityCluster, entityCollection) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entityCluster)) {
      throw new DeveloperError("entityCluster is required.");
    }
    if (!defined(entityCollection)) {
      throw new DeveloperError("entityCollection is required.");
    }
    //>>includeEnd('debug');

    entityCollection.collectionChanged.addEventListener(
      PointVisualizer.prototype._onCollectionChanged,
      this
    );

    this._cluster = entityCluster;
    this._entityCollection = entityCollection;
    this._items = new AssociativeArray();
    this._onCollectionChanged(entityCollection, entityCollection.values, [], []);
  }

  /**
   * Updates the primitives created by this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} This function always returns true.
   */
  PointVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }
    //>>includeEnd('debug');

    var items = this._items.values;
    var cluster = this._cluster;
    for (var i = 0, len = items.length; i < len; i++) {
      var item = items[i];
      var entity = item.entity;
      var pointGraphics = entity._point;
      var pointPrimitive = item.pointPrimitive;
      var billboard = item.billboard;
      var heightReference = Property.getValueOrDefault(
        pointGraphics._heightReference,
        time,
        HeightReference$1.NONE
      );
      var show =
        entity.isShowing &&
        entity.isAvailable(time) &&
        Property.getValueOrDefault(pointGraphics._show, time, true);
      var position;
      if (show) {
        position = Property.getValueOrUndefined(
          entity._position,
          time,
          positionScratch$b
        );
        show = defined(position);
      }
      if (!show) {
        returnPrimitive$2(item, entity, cluster);
        continue;
      }

      if (!Property.isConstant(entity._position)) {
        cluster._clusterDirty = true;
      }

      var needsRedraw = false;
      var updateClamping = false;
      if (heightReference !== HeightReference$1.NONE && !defined(billboard)) {
        if (defined(pointPrimitive)) {
          returnPrimitive$2(item, entity, cluster);
          pointPrimitive = undefined;
        }

        billboard = cluster.getBillboard(entity);
        billboard.id = entity;
        billboard.image = undefined;
        item.billboard = billboard;
        needsRedraw = true;

        // If this new billboard happens to have a position and height reference that match our new values,
        // billboard._updateClamping will not be called automatically. That's a problem because the clamped
        // height may be based on different terrain than is now loaded. So we'll manually call
        // _updateClamping below.
        updateClamping =
          Cartesian3.equals(billboard.position, position) &&
          billboard.heightReference === heightReference;
      } else if (
        heightReference === HeightReference$1.NONE &&
        !defined(pointPrimitive)
      ) {
        if (defined(billboard)) {
          returnPrimitive$2(item, entity, cluster);
          billboard = undefined;
        }

        pointPrimitive = cluster.getPoint(entity);
        pointPrimitive.id = entity;
        item.pointPrimitive = pointPrimitive;
      }

      if (defined(pointPrimitive)) {
        pointPrimitive.show = true;
        pointPrimitive.position = position;
        pointPrimitive.scaleByDistance = Property.getValueOrUndefined(
          pointGraphics._scaleByDistance,
          time,
          scaleByDistanceScratch$2
        );
        pointPrimitive.translucencyByDistance = Property.getValueOrUndefined(
          pointGraphics._translucencyByDistance,
          time,
          translucencyByDistanceScratch$2
        );
        pointPrimitive.color = Property.getValueOrDefault(
          pointGraphics._color,
          time,
          defaultColor$7,
          colorScratch$6
        );
        pointPrimitive.outlineColor = Property.getValueOrDefault(
          pointGraphics._outlineColor,
          time,
          defaultOutlineColor$3,
          outlineColorScratch$1
        );
        pointPrimitive.outlineWidth = Property.getValueOrDefault(
          pointGraphics._outlineWidth,
          time,
          defaultOutlineWidth$2
        );
        pointPrimitive.pixelSize = Property.getValueOrDefault(
          pointGraphics._pixelSize,
          time,
          defaultPixelSize
        );
        pointPrimitive.distanceDisplayCondition = Property.getValueOrUndefined(
          pointGraphics._distanceDisplayCondition,
          time,
          distanceDisplayConditionScratch$7
        );
        pointPrimitive.disableDepthTestDistance = Property.getValueOrDefault(
          pointGraphics._disableDepthTestDistance,
          time,
          defaultDisableDepthTestDistance
        );
      } else if (defined(billboard)) {
        billboard.show = true;
        billboard.position = position;
        billboard.scaleByDistance = Property.getValueOrUndefined(
          pointGraphics._scaleByDistance,
          time,
          scaleByDistanceScratch$2
        );
        billboard.translucencyByDistance = Property.getValueOrUndefined(
          pointGraphics._translucencyByDistance,
          time,
          translucencyByDistanceScratch$2
        );
        billboard.distanceDisplayCondition = Property.getValueOrUndefined(
          pointGraphics._distanceDisplayCondition,
          time,
          distanceDisplayConditionScratch$7
        );
        billboard.disableDepthTestDistance = Property.getValueOrDefault(
          pointGraphics._disableDepthTestDistance,
          time,
          defaultDisableDepthTestDistance
        );
        billboard.heightReference = heightReference;

        var newColor = Property.getValueOrDefault(
          pointGraphics._color,
          time,
          defaultColor$7,
          colorScratch$6
        );
        var newOutlineColor = Property.getValueOrDefault(
          pointGraphics._outlineColor,
          time,
          defaultOutlineColor$3,
          outlineColorScratch$1
        );
        var newOutlineWidth = Math.round(
          Property.getValueOrDefault(
            pointGraphics._outlineWidth,
            time,
            defaultOutlineWidth$2
          )
        );
        var newPixelSize = Math.max(
          1,
          Math.round(
            Property.getValueOrDefault(
              pointGraphics._pixelSize,
              time,
              defaultPixelSize
            )
          )
        );

        if (newOutlineWidth > 0) {
          billboard.scale = 1.0;
          needsRedraw =
            needsRedraw || //
            newOutlineWidth !== item.outlineWidth || //
            newPixelSize !== item.pixelSize || //
            !Color.equals(newColor, item.color) || //
            !Color.equals(newOutlineColor, item.outlineColor);
        } else {
          billboard.scale = newPixelSize / 50.0;
          newPixelSize = 50.0;
          needsRedraw =
            needsRedraw || //
            newOutlineWidth !== item.outlineWidth || //
            !Color.equals(newColor, item.color) || //
            !Color.equals(newOutlineColor, item.outlineColor);
        }

        if (needsRedraw) {
          item.color = Color.clone(newColor, item.color);
          item.outlineColor = Color.clone(newOutlineColor, item.outlineColor);
          item.pixelSize = newPixelSize;
          item.outlineWidth = newOutlineWidth;

          var centerAlpha = newColor.alpha;
          var cssColor = newColor.toCssColorString();
          var cssOutlineColor = newOutlineColor.toCssColorString();
          var textureId = JSON.stringify([
            cssColor,
            newPixelSize,
            cssOutlineColor,
            newOutlineWidth,
          ]);

          billboard.setImage(
            textureId,
            createBillboardPointCallback(
              centerAlpha,
              cssColor,
              cssOutlineColor,
              newOutlineWidth,
              newPixelSize
            )
          );
        }

        if (updateClamping) {
          billboard._updateClamping();
        }
      }
    }
    return true;
  };

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  PointVisualizer.prototype.getBoundingSphere = function (entity, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required.");
    }
    if (!defined(result)) {
      throw new DeveloperError("result is required.");
    }
    //>>includeEnd('debug');

    var item = this._items.get(entity.id);
    if (
      !defined(item) ||
      !(defined(item.pointPrimitive) || defined(item.billboard))
    ) {
      return BoundingSphereState$1.FAILED;
    }

    if (defined(item.pointPrimitive)) {
      result.center = Cartesian3.clone(
        item.pointPrimitive.position,
        result.center
      );
    } else {
      var billboard = item.billboard;
      if (!defined(billboard._clampedPosition)) {
        return BoundingSphereState$1.PENDING;
      }
      result.center = Cartesian3.clone(billboard._clampedPosition, result.center);
    }

    result.radius = 0;
    return BoundingSphereState$1.DONE;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  PointVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  PointVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      PointVisualizer.prototype._onCollectionChanged,
      this
    );
    var entities = this._entityCollection.values;
    for (var i = 0; i < entities.length; i++) {
      this._cluster.removePoint(entities[i]);
    }
    return destroyObject(this);
  };

  PointVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed,
    changed
  ) {
    var i;
    var entity;
    var items = this._items;
    var cluster = this._cluster;

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      if (defined(entity._point) && defined(entity._position)) {
        items.set(entity.id, new EntityData$3(entity));
      }
    }

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      if (defined(entity._point) && defined(entity._position)) {
        if (!items.contains(entity.id)) {
          items.set(entity.id, new EntityData$3(entity));
        }
      } else {
        returnPrimitive$2(items.get(entity.id), entity, cluster);
        items.remove(entity.id);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      returnPrimitive$2(items.get(entity.id), entity, cluster);
      items.remove(entity.id);
    }
  };

  function returnPrimitive$2(item, entity, cluster) {
    if (defined(item)) {
      var pointPrimitive = item.pointPrimitive;
      if (defined(pointPrimitive)) {
        item.pointPrimitive = undefined;
        cluster.removePoint(entity);
        return;
      }
      var billboard = item.billboard;
      if (defined(billboard)) {
        item.billboard = undefined;
        cluster.removeBillboard(entity);
      }
    }
  }

  var defaultZIndex$1 = new ConstantProperty(0);

  //We use this object to create one polyline collection per-scene.
  var polylineCollections = {};

  var scratchColor$i = new Color();
  var defaultMaterial$2 = new ColorMaterialProperty(Color.WHITE);
  var defaultShow$1 = new ConstantProperty(true);
  var defaultShadows$2 = new ConstantProperty(ShadowMode$1.DISABLED);
  var defaultDistanceDisplayCondition$6 = new ConstantProperty(
    new DistanceDisplayCondition()
  );
  var defaultClassificationType$1 = new ConstantProperty(ClassificationType$1.BOTH);

  function GeometryOptions() {
    this.vertexFormat = undefined;
    this.positions = undefined;
    this.width = undefined;
    this.arcType = undefined;
    this.granularity = undefined;
  }

  function GroundGeometryOptions() {
    this.positions = undefined;
    this.width = undefined;
    this.arcType = undefined;
    this.granularity = undefined;
  }

  /**
   * A {@link GeometryUpdater} for polylines.
   * Clients do not normally create this class directly, but instead rely on {@link DataSourceDisplay}.
   * @alias PolylineGeometryUpdater
   * @constructor
   *
   * @param {Entity} entity The entity containing the geometry to be visualized.
   * @param {Scene} scene The scene where visualization is taking place.
   */
  function PolylineGeometryUpdater(entity, scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(entity)) {
      throw new DeveloperError("entity is required");
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required");
    }
    //>>includeEnd('debug');

    this._entity = entity;
    this._scene = scene;
    this._entitySubscription = entity.definitionChanged.addEventListener(
      PolylineGeometryUpdater.prototype._onEntityPropertyChanged,
      this
    );
    this._fillEnabled = false;
    this._dynamic = false;
    this._geometryChanged = new Event();
    this._showProperty = undefined;
    this._materialProperty = undefined;
    this._shadowsProperty = undefined;
    this._distanceDisplayConditionProperty = undefined;
    this._classificationTypeProperty = undefined;
    this._depthFailMaterialProperty = undefined;
    this._geometryOptions = new GeometryOptions();
    this._groundGeometryOptions = new GroundGeometryOptions();
    this._id = "polyline-" + entity.id;
    this._clampToGround = false;
    this._supportsPolylinesOnTerrain = Entity.supportsPolylinesOnTerrain(scene);

    this._zIndex = 0;

    this._onEntityPropertyChanged(entity, "polyline", entity.polyline, undefined);
  }

  Object.defineProperties(PolylineGeometryUpdater.prototype, {
    /**
     * Gets the unique ID associated with this updater
     * @memberof PolylineGeometryUpdater.prototype
     * @type {String}
     * @readonly
     */
    id: {
      get: function () {
        return this._id;
      },
    },
    /**
     * Gets the entity associated with this geometry.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Entity}
     * @readonly
     */
    entity: {
      get: function () {
        return this._entity;
      },
    },
    /**
     * Gets a value indicating if the geometry has a fill component.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    fillEnabled: {
      get: function () {
        return this._fillEnabled;
      },
    },
    /**
     * Gets a value indicating if fill visibility varies with simulation time.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    hasConstantFill: {
      get: function () {
        return (
          !this._fillEnabled ||
          (!defined(this._entity.availability) &&
            Property.isConstant(this._showProperty))
        );
      },
    },
    /**
     * Gets the material property used to fill the geometry.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {MaterialProperty}
     * @readonly
     */
    fillMaterialProperty: {
      get: function () {
        return this._materialProperty;
      },
    },
    /**
     * Gets the material property used to fill the geometry when it fails the depth test.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {MaterialProperty}
     * @readonly
     */
    depthFailMaterialProperty: {
      get: function () {
        return this._depthFailMaterialProperty;
      },
    },
    /**
     * Gets a value indicating if the geometry has an outline component.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    outlineEnabled: {
      value: false,
    },
    /**
     * Gets a value indicating if outline visibility varies with simulation time.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    hasConstantOutline: {
      value: true,
    },
    /**
     * Gets the {@link Color} property for the geometry outline.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    outlineColorProperty: {
      value: undefined,
    },
    /**
     * Gets the property specifying whether the geometry
     * casts or receives shadows from light sources.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    shadowsProperty: {
      get: function () {
        return this._shadowsProperty;
      },
    },
    /**
     * Gets or sets the {@link DistanceDisplayCondition} Property specifying at what distance from the camera that this geometry will be displayed.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    distanceDisplayConditionProperty: {
      get: function () {
        return this._distanceDisplayConditionProperty;
      },
    },
    /**
     * Gets or sets the {@link ClassificationType} Property specifying if this geometry will classify terrain, 3D Tiles, or both when on the ground.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Property}
     * @readonly
     */
    classificationTypeProperty: {
      get: function () {
        return this._classificationTypeProperty;
      },
    },
    /**
     * Gets a value indicating if the geometry is time-varying.
     * If true, all visualization is delegated to the {@link DynamicGeometryUpdater}
     * returned by GeometryUpdater#createDynamicUpdater.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isDynamic: {
      get: function () {
        return this._dynamic;
      },
    },
    /**
     * Gets a value indicating if the geometry is closed.
     * This property is only valid for static geometry.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    isClosed: {
      value: false,
    },
    /**
     * Gets an event that is raised whenever the public properties
     * of this updater change.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    geometryChanged: {
      get: function () {
        return this._geometryChanged;
      },
    },

    /**
     * Gets a value indicating if the path of the line.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {ArcType}
     * @readonly
     */
    arcType: {
      get: function () {
        return this._arcType;
      },
    },

    /**
     * Gets a value indicating if the geometry is clamped to the ground.
     * Returns false if polylines on terrain is not supported.
     * @memberof PolylineGeometryUpdater.prototype
     *
     * @type {Boolean}
     * @readonly
     */
    clampToGround: {
      get: function () {
        return this._clampToGround && this._supportsPolylinesOnTerrain;
      },
    },

    /**
     * Gets the zindex
     * @type {Number}
     * @memberof PolylineGeometryUpdater.prototype
     * @readonly
     */
    zIndex: {
      get: function () {
        return this._zIndex;
      },
    },
  });

  /**
   * Checks if the geometry is outlined at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve visibility.
   * @returns {Boolean} true if geometry is outlined at the provided time, false otherwise.
   */
  PolylineGeometryUpdater.prototype.isOutlineVisible = function (time) {
    return false;
  };

  /**
   * Checks if the geometry is filled at the provided time.
   *
   * @param {JulianDate} time The time for which to retrieve visibility.
   * @returns {Boolean} true if geometry is filled at the provided time, false otherwise.
   */
  PolylineGeometryUpdater.prototype.isFilled = function (time) {
    var entity = this._entity;
    var visible =
      this._fillEnabled &&
      entity.isAvailable(time) &&
      this._showProperty.getValue(time);
    return defaultValue(visible, false);
  };

  /**
   * Creates the geometry instance which represents the fill of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the filled portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent a filled geometry.
   */
  PolylineGeometryUpdater.prototype.createFillGeometryInstance = function (time) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(time)) {
      throw new DeveloperError("time is required.");
    }

    if (!this._fillEnabled) {
      throw new DeveloperError(
        "This instance does not represent a filled geometry."
      );
    }
    //>>includeEnd('debug');

    var entity = this._entity;
    var isAvailable = entity.isAvailable(time);
    var show = new ShowGeometryInstanceAttribute(
      isAvailable && entity.isShowing && this._showProperty.getValue(time)
    );
    var distanceDisplayCondition = this._distanceDisplayConditionProperty.getValue(
      time
    );
    var distanceDisplayConditionAttribute = DistanceDisplayConditionGeometryInstanceAttribute.fromDistanceDisplayCondition(
      distanceDisplayCondition
    );

    var attributes = {
      show: show,
      distanceDisplayCondition: distanceDisplayConditionAttribute,
    };

    var currentColor;
    if (this._materialProperty instanceof ColorMaterialProperty) {
      if (
        defined(this._materialProperty.color) &&
        (this._materialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._materialProperty.color.getValue(time, scratchColor$i);
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.color = ColorGeometryInstanceAttribute.fromColor(currentColor);
    }

    if (this.clampToGround) {
      return new GeometryInstance({
        id: entity,
        geometry: new GroundPolylineGeometry(this._groundGeometryOptions),
        attributes: attributes,
      });
    }

    if (
      defined(this._depthFailMaterialProperty) &&
      this._depthFailMaterialProperty instanceof ColorMaterialProperty
    ) {
      if (
        defined(this._depthFailMaterialProperty.color) &&
        (this._depthFailMaterialProperty.color.isConstant || isAvailable)
      ) {
        currentColor = this._depthFailMaterialProperty.color.getValue(
          time,
          scratchColor$i
        );
      }
      if (!defined(currentColor)) {
        currentColor = Color.WHITE;
      }
      attributes.depthFailColor = ColorGeometryInstanceAttribute.fromColor(
        currentColor
      );
    }

    return new GeometryInstance({
      id: entity,
      geometry: new PolylineGeometry(this._geometryOptions),
      attributes: attributes,
    });
  };

  /**
   * Creates the geometry instance which represents the outline of the geometry.
   *
   * @param {JulianDate} time The time to use when retrieving initial attribute values.
   * @returns {GeometryInstance} The geometry instance representing the outline portion of the geometry.
   *
   * @exception {DeveloperError} This instance does not represent an outlined geometry.
   */
  PolylineGeometryUpdater.prototype.createOutlineGeometryInstance = function (
    time
  ) {
    //>>includeStart('debug', pragmas.debug);
    throw new DeveloperError(
      "This instance does not represent an outlined geometry."
    );
    //>>includeEnd('debug');
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  PolylineGeometryUpdater.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys and resources used by the object.  Once an object is destroyed, it should not be used.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  PolylineGeometryUpdater.prototype.destroy = function () {
    this._entitySubscription();
    destroyObject(this);
  };

  PolylineGeometryUpdater.prototype._onEntityPropertyChanged = function (
    entity,
    propertyName,
    newValue,
    oldValue
  ) {
    if (!(propertyName === "availability" || propertyName === "polyline")) {
      return;
    }

    var polyline = this._entity.polyline;

    if (!defined(polyline)) {
      if (this._fillEnabled) {
        this._fillEnabled = false;
        this._geometryChanged.raiseEvent(this);
      }
      return;
    }

    var positionsProperty = polyline.positions;

    var show = polyline.show;
    if (
      (defined(show) &&
        show.isConstant &&
        !show.getValue(Iso8601.MINIMUM_VALUE)) || //
      !defined(positionsProperty)
    ) {
      if (this._fillEnabled) {
        this._fillEnabled = false;
        this._geometryChanged.raiseEvent(this);
      }
      return;
    }

    var zIndex = polyline.zIndex;
    var material = defaultValue(polyline.material, defaultMaterial$2);
    var isColorMaterial = material instanceof ColorMaterialProperty;
    this._materialProperty = material;
    this._depthFailMaterialProperty = polyline.depthFailMaterial;
    this._showProperty = defaultValue(show, defaultShow$1);
    this._shadowsProperty = defaultValue(polyline.shadows, defaultShadows$2);
    this._distanceDisplayConditionProperty = defaultValue(
      polyline.distanceDisplayCondition,
      defaultDistanceDisplayCondition$6
    );
    this._classificationTypeProperty = defaultValue(
      polyline.classificationType,
      defaultClassificationType$1
    );
    this._fillEnabled = true;
    this._zIndex = defaultValue(zIndex, defaultZIndex$1);

    var width = polyline.width;
    var arcType = polyline.arcType;
    var clampToGround = polyline.clampToGround;
    var granularity = polyline.granularity;

    if (
      !positionsProperty.isConstant ||
      !Property.isConstant(width) ||
      !Property.isConstant(arcType) ||
      !Property.isConstant(granularity) ||
      !Property.isConstant(clampToGround) ||
      !Property.isConstant(zIndex)
    ) {
      if (!this._dynamic) {
        this._dynamic = true;
        this._geometryChanged.raiseEvent(this);
      }
    } else {
      var geometryOptions = this._geometryOptions;
      var positions = positionsProperty.getValue(
        Iso8601.MINIMUM_VALUE,
        geometryOptions.positions
      );

      //Because of the way we currently handle reference properties,
      //we can't automatically assume the positions are always valid.
      if (!defined(positions) || positions.length < 2) {
        if (this._fillEnabled) {
          this._fillEnabled = false;
          this._geometryChanged.raiseEvent(this);
        }
        return;
      }

      var vertexFormat;
      if (
        isColorMaterial &&
        (!defined(this._depthFailMaterialProperty) ||
          this._depthFailMaterialProperty instanceof ColorMaterialProperty)
      ) {
        vertexFormat = PolylineColorAppearance.VERTEX_FORMAT;
      } else {
        vertexFormat = PolylineMaterialAppearance.VERTEX_FORMAT;
      }

      geometryOptions.vertexFormat = vertexFormat;
      geometryOptions.positions = positions;
      geometryOptions.width = defined(width)
        ? width.getValue(Iso8601.MINIMUM_VALUE)
        : undefined;
      geometryOptions.arcType = defined(arcType)
        ? arcType.getValue(Iso8601.MINIMUM_VALUE)
        : undefined;
      geometryOptions.granularity = defined(granularity)
        ? granularity.getValue(Iso8601.MINIMUM_VALUE)
        : undefined;

      var groundGeometryOptions = this._groundGeometryOptions;
      groundGeometryOptions.positions = positions;
      groundGeometryOptions.width = geometryOptions.width;
      groundGeometryOptions.arcType = geometryOptions.arcType;
      groundGeometryOptions.granularity = geometryOptions.granularity;

      this._clampToGround = defined(clampToGround)
        ? clampToGround.getValue(Iso8601.MINIMUM_VALUE)
        : false;

      if (!this._clampToGround && defined(zIndex)) {
        oneTimeWarning(
          "Entity polylines must have clampToGround: true when using zIndex.  zIndex will be ignored."
        );
      }

      this._dynamic = false;
      this._geometryChanged.raiseEvent(this);
    }
  };

  /**
   * Creates the dynamic updater to be used when GeometryUpdater#isDynamic is true.
   *
   * @param {PrimitiveCollection} primitives The primitive collection to use.
   * @param {PrimitiveCollection|OrderedGroundPrimitiveCollection} groundPrimitives The primitive collection to use for ordered ground primitives.
   * @returns {DynamicGeometryUpdater} The dynamic updater used to update the geometry each frame.
   *
   * @exception {DeveloperError} This instance does not represent dynamic geometry.
   * @private
   */
  PolylineGeometryUpdater.prototype.createDynamicUpdater = function (
    primitives,
    groundPrimitives
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("primitives", primitives);
    Check.defined("groundPrimitives", groundPrimitives);

    if (!this._dynamic) {
      throw new DeveloperError(
        "This instance does not represent dynamic geometry."
      );
    }
    //>>includeEnd('debug');

    return new DynamicGeometryUpdater$1(primitives, groundPrimitives, this);
  };

  /**
   * @private
   */
  var generateCartesianArcOptions = {
    positions: undefined,
    granularity: undefined,
    height: undefined,
    ellipsoid: undefined,
  };

  function DynamicGeometryUpdater$1(primitives, groundPrimitives, geometryUpdater) {
    this._line = undefined;
    this._primitives = primitives;
    this._groundPrimitives = groundPrimitives;
    this._groundPolylinePrimitive = undefined;
    this._material = undefined;
    this._geometryUpdater = geometryUpdater;
    this._positions = [];
  }

  function getLine(dynamicGeometryUpdater) {
    if (defined(dynamicGeometryUpdater._line)) {
      return dynamicGeometryUpdater._line;
    }

    var sceneId = dynamicGeometryUpdater._geometryUpdater._scene.id;
    var polylineCollection = polylineCollections[sceneId];
    var primitives = dynamicGeometryUpdater._primitives;
    if (!defined(polylineCollection) || polylineCollection.isDestroyed()) {
      polylineCollection = new PolylineCollection();
      polylineCollections[sceneId] = polylineCollection;
      primitives.add(polylineCollection);
    } else if (!primitives.contains(polylineCollection)) {
      primitives.add(polylineCollection);
    }

    var line = polylineCollection.add();
    line.id = dynamicGeometryUpdater._geometryUpdater._entity;
    dynamicGeometryUpdater._line = line;
    return line;
  }

  DynamicGeometryUpdater$1.prototype.update = function (time) {
    var geometryUpdater = this._geometryUpdater;
    var entity = geometryUpdater._entity;
    var polyline = entity.polyline;

    var positionsProperty = polyline.positions;
    var positions = Property.getValueOrUndefined(
      positionsProperty,
      time,
      this._positions
    );

    // Synchronize with geometryUpdater for GroundPolylinePrimitive
    geometryUpdater._clampToGround = Property.getValueOrDefault(
      polyline._clampToGround,
      time,
      false
    );
    geometryUpdater._groundGeometryOptions.positions = positions;
    geometryUpdater._groundGeometryOptions.width = Property.getValueOrDefault(
      polyline._width,
      time,
      1
    );
    geometryUpdater._groundGeometryOptions.arcType = Property.getValueOrDefault(
      polyline._arcType,
      time,
      ArcType$1.GEODESIC
    );
    geometryUpdater._groundGeometryOptions.granularity = Property.getValueOrDefault(
      polyline._granularity,
      time,
      9999
    );

    var groundPrimitives = this._groundPrimitives;

    if (defined(this._groundPolylinePrimitive)) {
      groundPrimitives.remove(this._groundPolylinePrimitive); // destroys by default
      this._groundPolylinePrimitive = undefined;
    }

    if (geometryUpdater.clampToGround) {
      if (
        !entity.isShowing ||
        !entity.isAvailable(time) ||
        !Property.getValueOrDefault(polyline._show, time, true)
      ) {
        return;
      }

      if (!defined(positions) || positions.length < 2) {
        return;
      }

      var fillMaterialProperty = geometryUpdater.fillMaterialProperty;
      var appearance;
      if (fillMaterialProperty instanceof ColorMaterialProperty) {
        appearance = new PolylineColorAppearance();
      } else {
        var material = MaterialProperty.getValue(
          time,
          fillMaterialProperty,
          this._material
        );
        appearance = new PolylineMaterialAppearance({
          material: material,
          translucent: material.isTranslucent(),
        });
        this._material = material;
      }

      this._groundPolylinePrimitive = groundPrimitives.add(
        new GroundPolylinePrimitive({
          geometryInstances: geometryUpdater.createFillGeometryInstance(time),
          appearance: appearance,
          classificationType: geometryUpdater.classificationTypeProperty.getValue(
            time
          ),
          asynchronous: false,
        }),
        Property.getValueOrUndefined(geometryUpdater.zIndex, time)
      );

      // Hide the polyline in the collection, if any
      if (defined(this._line)) {
        this._line.show = false;
      }
      return;
    }

    var line = getLine(this);

    if (
      !entity.isShowing ||
      !entity.isAvailable(time) ||
      !Property.getValueOrDefault(polyline._show, time, true)
    ) {
      line.show = false;
      return;
    }

    if (!defined(positions) || positions.length < 2) {
      line.show = false;
      return;
    }

    var arcType = ArcType$1.GEODESIC;
    arcType = Property.getValueOrDefault(polyline._arcType, time, arcType);

    var globe = geometryUpdater._scene.globe;
    if (arcType !== ArcType$1.NONE && defined(globe)) {
      generateCartesianArcOptions.ellipsoid = globe.ellipsoid;
      generateCartesianArcOptions.positions = positions;
      generateCartesianArcOptions.granularity = Property.getValueOrUndefined(
        polyline._granularity,
        time
      );
      generateCartesianArcOptions.height = PolylinePipeline.extractHeights(
        positions,
        globe.ellipsoid
      );
      if (arcType === ArcType$1.GEODESIC) {
        positions = PolylinePipeline.generateCartesianArc(
          generateCartesianArcOptions
        );
      } else {
        positions = PolylinePipeline.generateCartesianRhumbArc(
          generateCartesianArcOptions
        );
      }
    }

    line.show = true;
    line.positions = positions.slice();
    line.material = MaterialProperty.getValue(
      time,
      geometryUpdater.fillMaterialProperty,
      line.material
    );
    line.width = Property.getValueOrDefault(polyline._width, time, 1);
    line.distanceDisplayCondition = Property.getValueOrUndefined(
      polyline._distanceDisplayCondition,
      time,
      line.distanceDisplayCondition
    );
  };

  DynamicGeometryUpdater$1.prototype.getBoundingSphere = function (result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("result", result);
    //>>includeEnd('debug');

    if (!this._geometryUpdater.clampToGround) {
      var line = getLine(this);
      if (line.show && line.positions.length > 0) {
        BoundingSphere.fromPoints(line.positions, result);
        return BoundingSphereState$1.DONE;
      }
    } else {
      var groundPolylinePrimitive = this._groundPolylinePrimitive;
      if (
        defined(groundPolylinePrimitive) &&
        groundPolylinePrimitive.show &&
        groundPolylinePrimitive.ready
      ) {
        var attributes = groundPolylinePrimitive.getGeometryInstanceAttributes(
          this._geometryUpdater._entity
        );
        if (defined(attributes) && defined(attributes.boundingSphere)) {
          BoundingSphere.clone(attributes.boundingSphere, result);
          return BoundingSphereState$1.DONE;
        }
      }

      if (defined(groundPolylinePrimitive) && !groundPolylinePrimitive.ready) {
        return BoundingSphereState$1.PENDING;
      }

      return BoundingSphereState$1.DONE;
    }

    return BoundingSphereState$1.FAILED;
  };

  DynamicGeometryUpdater$1.prototype.isDestroyed = function () {
    return false;
  };

  DynamicGeometryUpdater$1.prototype.destroy = function () {
    var geometryUpdater = this._geometryUpdater;
    var sceneId = geometryUpdater._scene.id;
    var polylineCollection = polylineCollections[sceneId];
    if (defined(polylineCollection)) {
      polylineCollection.remove(this._line);
      if (polylineCollection.length === 0) {
        this._primitives.removeAndDestroy(polylineCollection);
        delete polylineCollections[sceneId];
      }
    }
    if (defined(this._groundPolylinePrimitive)) {
      this._groundPrimitives.remove(this._groundPolylinePrimitive);
    }
    destroyObject(this);
  };

  var scratchColor$j = new Color();
  var distanceDisplayConditionScratch$8 = new DistanceDisplayCondition();
  var defaultDistanceDisplayCondition$7 = new DistanceDisplayCondition();

  // Encapsulates a Primitive and all the entities that it represents.
  function Batch$5(
    orderedGroundPrimitives,
    classificationType,
    materialProperty,
    zIndex,
    asynchronous
  ) {
    var appearanceType;
    if (materialProperty instanceof ColorMaterialProperty) {
      appearanceType = PolylineColorAppearance;
    } else {
      appearanceType = PolylineMaterialAppearance;
    }

    this.orderedGroundPrimitives = orderedGroundPrimitives; // scene level primitive collection
    this.classificationType = classificationType;
    this.appearanceType = appearanceType;
    this.materialProperty = materialProperty;
    this.updaters = new AssociativeArray();
    this.createPrimitive = true;
    this.primitive = undefined; // a GroundPolylinePrimitive encapsulating all the entities
    this.oldPrimitive = undefined;
    this.geometry = new AssociativeArray();
    this.material = undefined;
    this.updatersWithAttributes = new AssociativeArray();
    this.attributes = new AssociativeArray();
    this.invalidated = false;
    this.removeMaterialSubscription = materialProperty.definitionChanged.addEventListener(
      Batch$5.prototype.onMaterialChanged,
      this
    );
    this.subscriptions = new AssociativeArray();
    this.showsUpdated = new AssociativeArray();
    this.zIndex = zIndex;

    this._asynchronous = asynchronous;
  }

  Batch$5.prototype.onMaterialChanged = function () {
    this.invalidated = true;
  };

  // Check if the given updater's material is compatible with this batch
  Batch$5.prototype.isMaterial = function (updater) {
    var material = this.materialProperty;
    var updaterMaterial = updater.fillMaterialProperty;

    if (
      updaterMaterial === material ||
      (updaterMaterial instanceof ColorMaterialProperty &&
        material instanceof ColorMaterialProperty)
    ) {
      return true;
    }
    return defined(material) && material.equals(updaterMaterial);
  };

  Batch$5.prototype.add = function (time, updater, geometryInstance) {
    var id = updater.id;
    this.updaters.set(id, updater);
    this.geometry.set(id, geometryInstance);
    // Updaters with dynamic attributes must be tracked separately, may exit the batch
    if (
      !updater.hasConstantFill ||
      !updater.fillMaterialProperty.isConstant ||
      !Property.isConstant(updater.distanceDisplayConditionProperty)
    ) {
      this.updatersWithAttributes.set(id, updater);
    } else {
      var that = this;
      // Listen for show changes. These will be synchronized in updateShows.
      this.subscriptions.set(
        id,
        updater.entity.definitionChanged.addEventListener(function (
          entity,
          propertyName,
          newValue,
          oldValue
        ) {
          if (propertyName === "isShowing") {
            that.showsUpdated.set(updater.id, updater);
          }
        })
      );
    }
    this.createPrimitive = true;
  };

  Batch$5.prototype.remove = function (updater) {
    var id = updater.id;
    this.createPrimitive = this.geometry.remove(id) || this.createPrimitive;
    if (this.updaters.remove(id)) {
      this.updatersWithAttributes.remove(id);
      var unsubscribe = this.subscriptions.get(id);
      if (defined(unsubscribe)) {
        unsubscribe();
        this.subscriptions.remove(id);
      }
      return true;
    }
    return false;
  };

  Batch$5.prototype.update = function (time) {
    var isUpdated = true;
    var primitive = this.primitive;
    var orderedGroundPrimitives = this.orderedGroundPrimitives;
    var geometries = this.geometry.values;
    var i;

    if (this.createPrimitive) {
      var geometriesLength = geometries.length;
      if (geometriesLength > 0) {
        if (defined(primitive)) {
          // Keep a handle to the old primitive so it can be removed when the updated version is ready.
          if (!defined(this.oldPrimitive)) {
            this.oldPrimitive = primitive;
          } else {
            // For if the new primitive changes again before it is ready.
            orderedGroundPrimitives.remove(primitive);
          }
        }

        primitive = new GroundPolylinePrimitive({
          show: false,
          asynchronous: this._asynchronous,
          geometryInstances: geometries.slice(),
          appearance: new this.appearanceType(),
          classificationType: this.classificationType,
        });

        if (this.appearanceType === PolylineMaterialAppearance) {
          this.material = MaterialProperty.getValue(
            time,
            this.materialProperty,
            this.material
          );
          primitive.appearance.material = this.material;
        }

        orderedGroundPrimitives.add(primitive, this.zIndex);
        isUpdated = false;
      } else {
        if (defined(primitive)) {
          orderedGroundPrimitives.remove(primitive);
          primitive = undefined;
        }
        var oldPrimitive = this.oldPrimitive;
        if (defined(oldPrimitive)) {
          orderedGroundPrimitives.remove(oldPrimitive);
          this.oldPrimitive = undefined;
        }
      }

      this.attributes.removeAll();
      this.primitive = primitive;
      this.createPrimitive = false;
    } else if (defined(primitive) && primitive.ready) {
      primitive.show = true;
      if (defined(this.oldPrimitive)) {
        orderedGroundPrimitives.remove(this.oldPrimitive);
        this.oldPrimitive = undefined;
      }

      if (this.appearanceType === PolylineMaterialAppearance) {
        this.material = MaterialProperty.getValue(
          time,
          this.materialProperty,
          this.material
        );
        this.primitive.appearance.material = this.material;
      }
      var updatersWithAttributes = this.updatersWithAttributes.values;
      var length = updatersWithAttributes.length;
      for (i = 0; i < length; i++) {
        var updater = updatersWithAttributes[i];
        var entity = updater.entity;
        var instance = this.geometry.get(updater.id);

        var attributes = this.attributes.get(instance.id.id);
        if (!defined(attributes)) {
          attributes = primitive.getGeometryInstanceAttributes(instance.id);
          this.attributes.set(instance.id.id, attributes);
        }

        if (!updater.fillMaterialProperty.isConstant) {
          var colorProperty = updater.fillMaterialProperty.color;
          var resultColor = Property.getValueOrDefault(
            colorProperty,
            time,
            Color.WHITE,
            scratchColor$j
          );
          if (!Color.equals(attributes._lastColor, resultColor)) {
            attributes._lastColor = Color.clone(
              resultColor,
              attributes._lastColor
            );
            attributes.color = ColorGeometryInstanceAttribute.toValue(
              resultColor,
              attributes.color
            );
          }
        }

        var show =
          entity.isShowing && (updater.hasConstantFill || updater.isFilled(time));
        var currentShow = attributes.show[0] === 1;
        if (show !== currentShow) {
          attributes.show = ShowGeometryInstanceAttribute.toValue(
            show,
            attributes.show
          );
        }

        var distanceDisplayConditionProperty =
          updater.distanceDisplayConditionProperty;
        if (!Property.isConstant(distanceDisplayConditionProperty)) {
          var distanceDisplayCondition = Property.getValueOrDefault(
            distanceDisplayConditionProperty,
            time,
            defaultDistanceDisplayCondition$7,
            distanceDisplayConditionScratch$8
          );
          if (
            !DistanceDisplayCondition.equals(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            )
          ) {
            attributes._lastDistanceDisplayCondition = DistanceDisplayCondition.clone(
              distanceDisplayCondition,
              attributes._lastDistanceDisplayCondition
            );
            attributes.distanceDisplayCondition = DistanceDisplayConditionGeometryInstanceAttribute.toValue(
              distanceDisplayCondition,
              attributes.distanceDisplayCondition
            );
          }
        }
      }

      this.updateShows(primitive);
    } else if (defined(primitive) && !primitive.ready) {
      isUpdated = false;
    }
    return isUpdated;
  };

  Batch$5.prototype.updateShows = function (primitive) {
    var showsUpdated = this.showsUpdated.values;
    var length = showsUpdated.length;
    for (var i = 0; i < length; i++) {
      var updater = showsUpdated[i];
      var entity = updater.entity;
      var instance = this.geometry.get(updater.id);

      var attributes = this.attributes.get(instance.id.id);
      if (!defined(attributes)) {
        attributes = primitive.getGeometryInstanceAttributes(instance.id);
        this.attributes.set(instance.id.id, attributes);
      }

      var show = entity.isShowing;
      var currentShow = attributes.show[0] === 1;
      if (show !== currentShow) {
        attributes.show = ShowGeometryInstanceAttribute.toValue(
          show,
          attributes.show
        );
        instance.attributes.show.value[0] = attributes.show[0];
      }
    }
    this.showsUpdated.removeAll();
  };

  Batch$5.prototype.contains = function (updater) {
    return this.updaters.contains(updater.id);
  };

  Batch$5.prototype.getBoundingSphere = function (updater, result) {
    var primitive = this.primitive;
    if (!primitive.ready) {
      return BoundingSphereState$1.PENDING;
    }
    var attributes = primitive.getGeometryInstanceAttributes(updater.entity);
    if (
      !defined(attributes) ||
      !defined(attributes.boundingSphere) ||
      (defined(attributes.show) && attributes.show[0] === 0)
    ) {
      return BoundingSphereState$1.FAILED;
    }
    attributes.boundingSphere.clone(result);
    return BoundingSphereState$1.DONE;
  };

  Batch$5.prototype.destroy = function () {
    var primitive = this.primitive;
    var orderedGroundPrimitives = this.orderedGroundPrimitives;
    if (defined(primitive)) {
      orderedGroundPrimitives.remove(primitive);
    }
    var oldPrimitive = this.oldPrimitive;
    if (defined(oldPrimitive)) {
      orderedGroundPrimitives.remove(oldPrimitive);
    }
    this.removeMaterialSubscription();
  };

  /**
   * @private
   */
  function StaticGroundPolylinePerMaterialBatch(
    orderedGroundPrimitives,
    classificationType,
    asynchronous
  ) {
    this._items = [];
    this._orderedGroundPrimitives = orderedGroundPrimitives;
    this._classificationType = classificationType;
    this._asynchronous = defaultValue(asynchronous, true);
  }

  StaticGroundPolylinePerMaterialBatch.prototype.add = function (time, updater) {
    var items = this._items;
    var length = items.length;
    var geometryInstance = updater.createFillGeometryInstance(time);
    var zIndex = Property.getValueOrDefault(updater.zIndex, 0);
    // Check if the Entity represented by the updater has the same material or a material representable with per-instance color.
    for (var i = 0; i < length; ++i) {
      var item = items[i];
      if (item.isMaterial(updater) && item.zIndex === zIndex) {
        item.add(time, updater, geometryInstance);
        return;
      }
    }
    // If a compatible batch wasn't found, create a new batch.
    var batch = new Batch$5(
      this._orderedGroundPrimitives,
      this._classificationType,
      updater.fillMaterialProperty,
      zIndex,
      this._asynchronous
    );
    batch.add(time, updater, geometryInstance);
    items.push(batch);
  };

  StaticGroundPolylinePerMaterialBatch.prototype.remove = function (updater) {
    var items = this._items;
    var length = items.length;
    for (var i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.remove(updater)) {
        if (item.updaters.length === 0) {
          items.splice(i, 1);
          item.destroy();
        }
        break;
      }
    }
  };

  StaticGroundPolylinePerMaterialBatch.prototype.update = function (time) {
    var i;
    var items = this._items;
    var length = items.length;

    for (i = length - 1; i >= 0; i--) {
      var item = items[i];
      if (item.invalidated) {
        items.splice(i, 1);
        var updaters = item.updaters.values;
        var updatersLength = updaters.length;
        for (var h = 0; h < updatersLength; h++) {
          this.add(time, updaters[h]);
        }
        item.destroy();
      }
    }

    var isUpdated = true;
    for (i = 0; i < items.length; i++) {
      isUpdated = items[i].update(time) && isUpdated;
    }
    return isUpdated;
  };

  StaticGroundPolylinePerMaterialBatch.prototype.getBoundingSphere = function (
    updater,
    result
  ) {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      var item = items[i];
      if (item.contains(updater)) {
        return item.getBoundingSphere(updater, result);
      }
    }
    return BoundingSphereState$1.FAILED;
  };

  StaticGroundPolylinePerMaterialBatch.prototype.removeAllPrimitives = function () {
    var items = this._items;
    var length = items.length;
    for (var i = 0; i < length; i++) {
      items[i].destroy();
    }
    this._items.length = 0;
  };

  var emptyArray$1 = [];

  function removeUpdater(that, updater) {
    //We don't keep track of which batch an updater is in, so just remove it from all of them.
    var batches = that._batches;
    var length = batches.length;
    for (var i = 0; i < length; i++) {
      batches[i].remove(updater);
    }
  }

  function insertUpdaterIntoBatch(that, time, updater) {
    if (updater.isDynamic) {
      that._dynamicBatch.add(time, updater);
      return;
    }

    if (updater.clampToGround && updater.fillEnabled) {
      // Also checks for support
      var classificationType = updater.classificationTypeProperty.getValue(time);
      that._groundBatches[classificationType].add(time, updater);
      return;
    }

    var shadows;
    if (updater.fillEnabled) {
      shadows = updater.shadowsProperty.getValue(time);
    }

    var multiplier = 0;
    if (defined(updater.depthFailMaterialProperty)) {
      multiplier =
        updater.depthFailMaterialProperty instanceof ColorMaterialProperty
          ? 1
          : 2;
    }

    var index;
    if (defined(shadows)) {
      index = shadows + multiplier * ShadowMode$1.NUMBER_OF_SHADOW_MODES;
    }

    if (updater.fillEnabled) {
      if (updater.fillMaterialProperty instanceof ColorMaterialProperty) {
        that._colorBatches[index].add(time, updater);
      } else {
        that._materialBatches[index].add(time, updater);
      }
    }
  }

  /**
   * A visualizer for polylines represented by {@link Primitive} instances.
   * @alias PolylineVisualizer
   * @constructor
   *
   * @param {Scene} scene The scene the primitives will be rendered in.
   * @param {EntityCollection} entityCollection The entityCollection to visualize.
   * @param {PrimitiveCollection} [primitives=scene.primitives] A collection to add primitives related to the entities
   * @param {PrimitiveCollection} [groundPrimitives=scene.groundPrimitives] A collection to add ground primitives related to the entities
   */
  function PolylineVisualizer(
    scene,
    entityCollection,
    primitives,
    groundPrimitives
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("scene", scene);
    Check.defined("entityCollection", entityCollection);
    //>>includeEnd('debug');

    groundPrimitives = defaultValue(groundPrimitives, scene.groundPrimitives);
    primitives = defaultValue(primitives, scene.primitives);

    this._scene = scene;
    this._primitives = primitives;
    this._entityCollection = undefined;
    this._addedObjects = new AssociativeArray();
    this._removedObjects = new AssociativeArray();
    this._changedObjects = new AssociativeArray();

    var i;
    var numberOfShadowModes = ShadowMode$1.NUMBER_OF_SHADOW_MODES;
    this._colorBatches = new Array(numberOfShadowModes * 3);
    this._materialBatches = new Array(numberOfShadowModes * 3);

    for (i = 0; i < numberOfShadowModes; ++i) {
      this._colorBatches[i] = new StaticGeometryColorBatch(
        primitives,
        PolylineColorAppearance,
        undefined,
        false,
        i
      ); // no depth fail appearance
      this._materialBatches[i] = new StaticGeometryPerMaterialBatch(
        primitives,
        PolylineMaterialAppearance,
        undefined,
        false,
        i
      );

      this._colorBatches[i + numberOfShadowModes] = new StaticGeometryColorBatch(
        primitives,
        PolylineColorAppearance,
        PolylineColorAppearance,
        false,
        i
      ); //depth fail appearance variations
      this._materialBatches[
        i + numberOfShadowModes
      ] = new StaticGeometryPerMaterialBatch(
        primitives,
        PolylineMaterialAppearance,
        PolylineColorAppearance,
        false,
        i
      );

      this._colorBatches[
        i + numberOfShadowModes * 2
      ] = new StaticGeometryColorBatch(
        primitives,
        PolylineColorAppearance,
        PolylineMaterialAppearance,
        false,
        i
      );
      this._materialBatches[
        i + numberOfShadowModes * 2
      ] = new StaticGeometryPerMaterialBatch(
        primitives,
        PolylineMaterialAppearance,
        PolylineMaterialAppearance,
        false,
        i
      );
    }

    this._dynamicBatch = new DynamicGeometryBatch(primitives, groundPrimitives);

    var numberOfClassificationTypes =
      ClassificationType$1.NUMBER_OF_CLASSIFICATION_TYPES;
    this._groundBatches = new Array(numberOfClassificationTypes);

    for (i = 0; i < numberOfClassificationTypes; ++i) {
      this._groundBatches[i] = new StaticGroundPolylinePerMaterialBatch(
        groundPrimitives,
        i
      );
    }

    this._batches = this._colorBatches.concat(
      this._materialBatches,
      this._dynamicBatch,
      this._groundBatches
    );

    this._subscriptions = new AssociativeArray();
    this._updaters = new AssociativeArray();

    this._entityCollection = entityCollection;
    entityCollection.collectionChanged.addEventListener(
      PolylineVisualizer.prototype._onCollectionChanged,
      this
    );
    this._onCollectionChanged(
      entityCollection,
      entityCollection.values,
      emptyArray$1
    );
  }

  /**
   * Updates all of the primitives created by this visualizer to match their
   * Entity counterpart at the given time.
   *
   * @param {JulianDate} time The time to update to.
   * @returns {Boolean} True if the visualizer successfully updated to the provided time,
   * false if the visualizer is waiting for asynchronous primitives to be created.
   */
  PolylineVisualizer.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var addedObjects = this._addedObjects;
    var added = addedObjects.values;
    var removedObjects = this._removedObjects;
    var removed = removedObjects.values;
    var changedObjects = this._changedObjects;
    var changed = changedObjects.values;

    var i;
    var entity;
    var id;
    var updater;

    for (i = changed.length - 1; i > -1; i--) {
      entity = changed[i];
      id = entity.id;
      updater = this._updaters.get(id);

      //If in a single update, an entity gets removed and a new instance
      //re-added with the same id, the updater no longer tracks the
      //correct entity, we need to both remove the old one and
      //add the new one, which is done by pushing the entity
      //onto the removed/added lists.
      if (updater.entity === entity) {
        removeUpdater(this, updater);
        insertUpdaterIntoBatch(this, time, updater);
      } else {
        removed.push(entity);
        added.push(entity);
      }
    }

    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      id = entity.id;
      updater = this._updaters.get(id);
      removeUpdater(this, updater);
      updater.destroy();
      this._updaters.remove(id);
      this._subscriptions.get(id)();
      this._subscriptions.remove(id);
    }

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      id = entity.id;
      updater = new PolylineGeometryUpdater(entity, this._scene);
      this._updaters.set(id, updater);
      insertUpdaterIntoBatch(this, time, updater);
      this._subscriptions.set(
        id,
        updater.geometryChanged.addEventListener(
          PolylineVisualizer._onGeometryChanged,
          this
        )
      );
    }

    addedObjects.removeAll();
    removedObjects.removeAll();
    changedObjects.removeAll();

    var isUpdated = true;
    var batches = this._batches;
    var length = batches.length;
    for (i = 0; i < length; i++) {
      isUpdated = batches[i].update(time) && isUpdated;
    }

    return isUpdated;
  };

  var getBoundingSphereArrayScratch$1 = [];
  var getBoundingSphereBoundingSphereScratch$1 = new BoundingSphere();

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  PolylineVisualizer.prototype.getBoundingSphere = function (entity, result) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("entity", entity);
    Check.defined("result", result);
    //>>includeEnd('debug');

    var boundingSpheres = getBoundingSphereArrayScratch$1;
    var tmp = getBoundingSphereBoundingSphereScratch$1;

    var count = 0;
    var state = BoundingSphereState$1.DONE;
    var batches = this._batches;
    var batchesLength = batches.length;
    var updater = this._updaters.get(entity.id);
    for (var i = 0; i < batchesLength; i++) {
      state = batches[i].getBoundingSphere(updater, tmp);
      if (state === BoundingSphereState$1.PENDING) {
        return BoundingSphereState$1.PENDING;
      } else if (state === BoundingSphereState$1.DONE) {
        boundingSpheres[count] = BoundingSphere.clone(
          tmp,
          boundingSpheres[count]
        );
        count++;
      }
    }

    if (count === 0) {
      return BoundingSphereState$1.FAILED;
    }

    boundingSpheres.length = count;
    BoundingSphere.fromBoundingSpheres(boundingSpheres, result);
    return BoundingSphereState$1.DONE;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  PolylineVisualizer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes and destroys all primitives created by this instance.
   */
  PolylineVisualizer.prototype.destroy = function () {
    this._entityCollection.collectionChanged.removeEventListener(
      PolylineVisualizer.prototype._onCollectionChanged,
      this
    );
    this._addedObjects.removeAll();
    this._removedObjects.removeAll();

    var i;
    var batches = this._batches;
    var length = batches.length;
    for (i = 0; i < length; i++) {
      batches[i].removeAllPrimitives();
    }

    var subscriptions = this._subscriptions.values;
    length = subscriptions.length;
    for (i = 0; i < length; i++) {
      subscriptions[i]();
    }
    this._subscriptions.removeAll();
    return destroyObject(this);
  };

  /**
   * @private
   */
  PolylineVisualizer._onGeometryChanged = function (updater) {
    var removedObjects = this._removedObjects;
    var changedObjects = this._changedObjects;

    var entity = updater.entity;
    var id = entity.id;

    if (!defined(removedObjects.get(id)) && !defined(changedObjects.get(id))) {
      changedObjects.set(id, entity);
    }
  };

  /**
   * @private
   */
  PolylineVisualizer.prototype._onCollectionChanged = function (
    entityCollection,
    added,
    removed
  ) {
    var addedObjects = this._addedObjects;
    var removedObjects = this._removedObjects;
    var changedObjects = this._changedObjects;

    var i;
    var id;
    var entity;
    for (i = removed.length - 1; i > -1; i--) {
      entity = removed[i];
      id = entity.id;
      if (!addedObjects.remove(id)) {
        removedObjects.set(id, entity);
        changedObjects.remove(id);
      }
    }

    for (i = added.length - 1; i > -1; i--) {
      entity = added[i];
      id = entity.id;
      if (removedObjects.remove(id)) {
        changedObjects.set(id, entity);
      } else {
        addedObjects.set(id, entity);
      }
    }
  };

  /**
   * Visualizes a collection of {@link DataSource} instances.
   * @alias DataSourceDisplay
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Scene} options.scene The scene in which to display the data.
   * @param {DataSourceCollection} options.dataSourceCollection The data sources to display.
   * @param {DataSourceDisplay.VisualizersCallback} [options.visualizersCallback=DataSourceDisplay.defaultVisualizersCallback]
   *        A function which creates an array of visualizers used for visualization.
   *        If undefined, all standard visualizers are used.
   */
  function DataSourceDisplay(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.scene", options.scene);
    Check.typeOf.object(
      "options.dataSourceCollection",
      options.dataSourceCollection
    );
    //>>includeEnd('debug');

    GroundPrimitive.initializeTerrainHeights();
    GroundPolylinePrimitive.initializeTerrainHeights();

    var scene = options.scene;
    var dataSourceCollection = options.dataSourceCollection;

    this._eventHelper = new EventHelper();
    this._eventHelper.add(
      dataSourceCollection.dataSourceAdded,
      this._onDataSourceAdded,
      this
    );
    this._eventHelper.add(
      dataSourceCollection.dataSourceRemoved,
      this._onDataSourceRemoved,
      this
    );
    this._eventHelper.add(
      dataSourceCollection.dataSourceMoved,
      this._onDataSourceMoved,
      this
    );
    this._eventHelper.add(scene.postRender, this._postRender, this);

    this._dataSourceCollection = dataSourceCollection;
    this._scene = scene;
    this._visualizersCallback = defaultValue(
      options.visualizersCallback,
      DataSourceDisplay.defaultVisualizersCallback
    );

    var primitivesAdded = false;
    var primitives = new PrimitiveCollection();
    var groundPrimitives = new PrimitiveCollection();

    if (dataSourceCollection.length > 0) {
      scene.primitives.add(primitives);
      scene.groundPrimitives.add(groundPrimitives);
      primitivesAdded = true;
    }

    this._primitives = primitives;
    this._groundPrimitives = groundPrimitives;

    for (var i = 0, len = dataSourceCollection.length; i < len; i++) {
      this._onDataSourceAdded(dataSourceCollection, dataSourceCollection.get(i));
    }

    var defaultDataSource = new CustomDataSource();
    this._onDataSourceAdded(undefined, defaultDataSource);
    this._defaultDataSource = defaultDataSource;

    var removeDefaultDataSourceListener;
    var removeDataSourceCollectionListener;
    if (!primitivesAdded) {
      var that = this;
      var addPrimitives = function () {
        scene.primitives.add(primitives);
        scene.groundPrimitives.add(groundPrimitives);
        removeDefaultDataSourceListener();
        removeDataSourceCollectionListener();
        that._removeDefaultDataSourceListener = undefined;
        that._removeDataSourceCollectionListener = undefined;
      };
      removeDefaultDataSourceListener = defaultDataSource.entities.collectionChanged.addEventListener(
        addPrimitives
      );
      removeDataSourceCollectionListener = dataSourceCollection.dataSourceAdded.addEventListener(
        addPrimitives
      );
    }

    this._removeDefaultDataSourceListener = removeDefaultDataSourceListener;
    this._removeDataSourceCollectionListener = removeDataSourceCollectionListener;

    this._ready = false;
  }

  /**
   * Gets or sets the default function which creates an array of visualizers used for visualization.
   * By default, this function uses all standard visualizers.
   *
   * @type {DataSourceDisplay.VisualizersCallback}
   */
  DataSourceDisplay.defaultVisualizersCallback = function (
    scene,
    entityCluster,
    dataSource
  ) {
    var entities = dataSource.entities;
    return [
      new BillboardVisualizer(entityCluster, entities),
      new GeometryVisualizer(
        scene,
        entities,
        dataSource._primitives,
        dataSource._groundPrimitives
      ),
      new LabelVisualizer(entityCluster, entities),
      new ModelVisualizer(scene, entities),
      new Cesium3DTilesetVisualizer(scene, entities),
      new PointVisualizer(entityCluster, entities),
      new PathVisualizer(scene, entities),
      new PolylineVisualizer(
        scene,
        entities,
        dataSource._primitives,
        dataSource._groundPrimitives
      ),
    ];
  };

  Object.defineProperties(DataSourceDisplay.prototype, {
    /**
     * Gets the scene associated with this display.
     * @memberof DataSourceDisplay.prototype
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },
    /**
     * Gets the collection of data sources to display.
     * @memberof DataSourceDisplay.prototype
     * @type {DataSourceCollection}
     */
    dataSources: {
      get: function () {
        return this._dataSourceCollection;
      },
    },
    /**
     * Gets the default data source instance which can be used to
     * manually create and visualize entities not tied to
     * a specific data source. This instance is always available
     * and does not appear in the list dataSources collection.
     * @memberof DataSourceDisplay.prototype
     * @type {CustomDataSource}
     */
    defaultDataSource: {
      get: function () {
        return this._defaultDataSource;
      },
    },

    /**
     * Gets a value indicating whether or not all entities in the data source are ready
     * @memberof DataSourceDisplay.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },
  });

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see DataSourceDisplay#destroy
   */
  DataSourceDisplay.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * dataSourceDisplay = dataSourceDisplay.destroy();
   *
   * @see DataSourceDisplay#isDestroyed
   */
  DataSourceDisplay.prototype.destroy = function () {
    this._eventHelper.removeAll();

    var dataSourceCollection = this._dataSourceCollection;
    for (var i = 0, length = dataSourceCollection.length; i < length; ++i) {
      this._onDataSourceRemoved(
        this._dataSourceCollection,
        dataSourceCollection.get(i)
      );
    }
    this._onDataSourceRemoved(undefined, this._defaultDataSource);

    if (defined(this._removeDefaultDataSourceListener)) {
      this._removeDefaultDataSourceListener();
      this._removeDataSourceCollectionListener();
    } else {
      this._scene.primitives.remove(this._primitives);
      this._scene.groundPrimitives.remove(this._groundPrimitives);
    }

    return destroyObject(this);
  };

  /**
   * Updates the display to the provided time.
   *
   * @param {JulianDate} time The simulation time.
   * @returns {Boolean} True if all data sources are ready to be displayed, false otherwise.
   */
  DataSourceDisplay.prototype.update = function (time) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    if (!ApproximateTerrainHeights.initialized) {
      this._ready = false;
      return false;
    }

    var result = true;

    var i;
    var x;
    var visualizers;
    var vLength;
    var dataSources = this._dataSourceCollection;
    var length = dataSources.length;
    for (i = 0; i < length; i++) {
      var dataSource = dataSources.get(i);
      if (defined(dataSource.update)) {
        result = dataSource.update(time) && result;
      }

      visualizers = dataSource._visualizers;
      vLength = visualizers.length;
      for (x = 0; x < vLength; x++) {
        result = visualizers[x].update(time) && result;
      }
    }

    visualizers = this._defaultDataSource._visualizers;
    vLength = visualizers.length;
    for (x = 0; x < vLength; x++) {
      result = visualizers[x].update(time) && result;
    }

    this._ready = result;

    return result;
  };

  DataSourceDisplay.prototype._postRender = function () {
    // Adds credits for all datasources
    var frameState = this._scene.frameState;
    var dataSources = this._dataSourceCollection;
    var length = dataSources.length;
    for (var i = 0; i < length; i++) {
      var dataSource = dataSources.get(i);

      var credit = dataSource.credit;
      if (defined(credit)) {
        frameState.creditDisplay.addCredit(credit);
      }

      // Credits from the resource that the user can't remove
      var credits = dataSource._resourceCredits;
      if (defined(credits)) {
        var creditCount = credits.length;
        for (var c = 0; c < creditCount; c++) {
          frameState.creditDisplay.addCredit(credits[c]);
        }
      }
    }
  };

  var getBoundingSphereArrayScratch$2 = [];
  var getBoundingSphereBoundingSphereScratch$2 = new BoundingSphere();

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {Boolean} allowPartial If true, pending bounding spheres are ignored and an answer will be returned from the currently available data.
   *                               If false, the the function will halt and return pending if any of the bounding spheres are pending.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  DataSourceDisplay.prototype.getBoundingSphere = function (
    entity,
    allowPartial,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("entity", entity);
    Check.typeOf.bool("allowPartial", allowPartial);
    Check.defined("result", result);
    //>>includeEnd('debug');

    if (!this._ready) {
      return BoundingSphereState$1.PENDING;
    }

    var i;
    var length;
    var dataSource = this._defaultDataSource;
    if (!dataSource.entities.contains(entity)) {
      dataSource = undefined;

      var dataSources = this._dataSourceCollection;
      length = dataSources.length;
      for (i = 0; i < length; i++) {
        var d = dataSources.get(i);
        if (d.entities.contains(entity)) {
          dataSource = d;
          break;
        }
      }
    }

    if (!defined(dataSource)) {
      return BoundingSphereState$1.FAILED;
    }

    var boundingSpheres = getBoundingSphereArrayScratch$2;
    var tmp = getBoundingSphereBoundingSphereScratch$2;

    var count = 0;
    var state = BoundingSphereState$1.DONE;
    var visualizers = dataSource._visualizers;
    var visualizersLength = visualizers.length;

    for (i = 0; i < visualizersLength; i++) {
      var visualizer = visualizers[i];
      if (defined(visualizer.getBoundingSphere)) {
        state = visualizers[i].getBoundingSphere(entity, tmp);
        if (!allowPartial && state === BoundingSphereState$1.PENDING) {
          return BoundingSphereState$1.PENDING;
        } else if (state === BoundingSphereState$1.DONE) {
          boundingSpheres[count] = BoundingSphere.clone(
            tmp,
            boundingSpheres[count]
          );
          count++;
        }
      }
    }

    if (count === 0) {
      return BoundingSphereState$1.FAILED;
    }

    boundingSpheres.length = count;
    BoundingSphere.fromBoundingSpheres(boundingSpheres, result);
    return BoundingSphereState$1.DONE;
  };

  DataSourceDisplay.prototype._onDataSourceAdded = function (
    dataSourceCollection,
    dataSource
  ) {
    var scene = this._scene;

    var displayPrimitives = this._primitives;
    var displayGroundPrimitives = this._groundPrimitives;

    var primitives = displayPrimitives.add(new PrimitiveCollection());
    var groundPrimitives = displayGroundPrimitives.add(
      new OrderedGroundPrimitiveCollection()
    );

    dataSource._primitives = primitives;
    dataSource._groundPrimitives = groundPrimitives;

    var entityCluster = dataSource.clustering;
    entityCluster._initialize(scene);

    primitives.add(entityCluster);

    dataSource._visualizers = this._visualizersCallback(
      scene,
      entityCluster,
      dataSource
    );
  };

  DataSourceDisplay.prototype._onDataSourceRemoved = function (
    dataSourceCollection,
    dataSource
  ) {
    var displayPrimitives = this._primitives;
    var displayGroundPrimitives = this._groundPrimitives;

    var primitives = dataSource._primitives;
    var groundPrimitives = dataSource._groundPrimitives;

    var entityCluster = dataSource.clustering;
    primitives.remove(entityCluster);

    var visualizers = dataSource._visualizers;
    var length = visualizers.length;
    for (var i = 0; i < length; i++) {
      visualizers[i].destroy();
    }

    displayPrimitives.remove(primitives);
    displayGroundPrimitives.remove(groundPrimitives);

    dataSource._visualizers = undefined;
  };

  DataSourceDisplay.prototype._onDataSourceMoved = function (
    dataSource,
    newIndex,
    oldIndex
  ) {
    var displayPrimitives = this._primitives;
    var displayGroundPrimitives = this._groundPrimitives;

    var primitives = dataSource._primitives;
    var groundPrimitives = dataSource._groundPrimitives;

    if (newIndex === oldIndex + 1) {
      displayPrimitives.raise(primitives);
      displayGroundPrimitives.raise(groundPrimitives);
    } else if (newIndex === oldIndex - 1) {
      displayPrimitives.lower(primitives);
      displayGroundPrimitives.lower(groundPrimitives);
    } else if (newIndex === 0) {
      displayPrimitives.lowerToBottom(primitives);
      displayGroundPrimitives.lowerToBottom(groundPrimitives);
      displayPrimitives.raise(primitives); // keep defaultDataSource primitives at index 0 since it's not in the collection
      displayGroundPrimitives.raise(groundPrimitives);
    } else {
      displayPrimitives.raiseToTop(primitives);
      displayGroundPrimitives.raiseToTop(groundPrimitives);
    }
  };

  var updateTransformMatrix3Scratch1 = new Matrix3();
  var updateTransformMatrix3Scratch2 = new Matrix3();
  var updateTransformMatrix3Scratch3 = new Matrix3();
  var updateTransformMatrix4Scratch = new Matrix4();
  var updateTransformCartesian3Scratch1 = new Cartesian3();
  var updateTransformCartesian3Scratch2 = new Cartesian3();
  var updateTransformCartesian3Scratch3 = new Cartesian3();
  var updateTransformCartesian3Scratch4 = new Cartesian3();
  var updateTransformCartesian3Scratch5 = new Cartesian3();
  var updateTransformCartesian3Scratch6 = new Cartesian3();
  var deltaTime = new JulianDate();
  var northUpAxisFactor = 1.25; // times ellipsoid's maximum radius

  function updateTransform(
    that,
    camera,
    updateLookAt,
    saveCamera,
    positionProperty,
    time,
    ellipsoid
  ) {
    var mode = that.scene.mode;
    var cartesian = positionProperty.getValue(time, that._lastCartesian);
    if (defined(cartesian)) {
      var hasBasis = false;
      var invertVelocity = false;
      var xBasis;
      var yBasis;
      var zBasis;

      if (mode === SceneMode$1.SCENE3D) {
        // The time delta was determined based on how fast satellites move compared to vehicles near the surface.
        // Slower moving vehicles will most likely default to east-north-up, while faster ones will be VVLH.
        JulianDate.addSeconds(time, 0.001, deltaTime);
        var deltaCartesian = positionProperty.getValue(
          deltaTime,
          updateTransformCartesian3Scratch1
        );

        // If no valid position at (time + 0.001), sample at (time - 0.001) and invert the vector
        if (!defined(deltaCartesian)) {
          JulianDate.addSeconds(time, -0.001, deltaTime);
          deltaCartesian = positionProperty.getValue(
            deltaTime,
            updateTransformCartesian3Scratch1
          );
          invertVelocity = true;
        }

        if (defined(deltaCartesian)) {
          var toInertial = Transforms.computeFixedToIcrfMatrix(
            time,
            updateTransformMatrix3Scratch1
          );
          var toInertialDelta = Transforms.computeFixedToIcrfMatrix(
            deltaTime,
            updateTransformMatrix3Scratch2
          );
          var toFixed;

          if (!defined(toInertial) || !defined(toInertialDelta)) {
            toFixed = Transforms.computeTemeToPseudoFixedMatrix(
              time,
              updateTransformMatrix3Scratch3
            );
            toInertial = Matrix3.transpose(
              toFixed,
              updateTransformMatrix3Scratch1
            );
            toInertialDelta = Transforms.computeTemeToPseudoFixedMatrix(
              deltaTime,
              updateTransformMatrix3Scratch2
            );
            Matrix3.transpose(toInertialDelta, toInertialDelta);
          } else {
            toFixed = Matrix3.transpose(
              toInertial,
              updateTransformMatrix3Scratch3
            );
          }

          var inertialCartesian = Matrix3.multiplyByVector(
            toInertial,
            cartesian,
            updateTransformCartesian3Scratch5
          );
          var inertialDeltaCartesian = Matrix3.multiplyByVector(
            toInertialDelta,
            deltaCartesian,
            updateTransformCartesian3Scratch6
          );

          Cartesian3.subtract(
            inertialCartesian,
            inertialDeltaCartesian,
            updateTransformCartesian3Scratch4
          );
          var inertialVelocity =
            Cartesian3.magnitude(updateTransformCartesian3Scratch4) * 1000.0; // meters/sec

          var mu = CesiumMath.GRAVITATIONALPARAMETER; // m^3 / sec^2
          var semiMajorAxis =
            -mu /
            (inertialVelocity * inertialVelocity -
              (2 * mu) / Cartesian3.magnitude(inertialCartesian));

          if (
            semiMajorAxis < 0 ||
            semiMajorAxis > northUpAxisFactor * ellipsoid.maximumRadius
          ) {
            // North-up viewing from deep space.

            // X along the nadir
            xBasis = updateTransformCartesian3Scratch2;
            Cartesian3.normalize(cartesian, xBasis);
            Cartesian3.negate(xBasis, xBasis);

            // Z is North
            zBasis = Cartesian3.clone(
              Cartesian3.UNIT_Z,
              updateTransformCartesian3Scratch3
            );

            // Y is along the cross of z and x (right handed basis / in the direction of motion)
            yBasis = Cartesian3.cross(
              zBasis,
              xBasis,
              updateTransformCartesian3Scratch1
            );
            if (Cartesian3.magnitude(yBasis) > CesiumMath.EPSILON7) {
              Cartesian3.normalize(xBasis, xBasis);
              Cartesian3.normalize(yBasis, yBasis);

              zBasis = Cartesian3.cross(
                xBasis,
                yBasis,
                updateTransformCartesian3Scratch3
              );
              Cartesian3.normalize(zBasis, zBasis);

              hasBasis = true;
            }
          } else if (
            !Cartesian3.equalsEpsilon(
              cartesian,
              deltaCartesian,
              CesiumMath.EPSILON7
            )
          ) {
            // Approximation of VVLH (Vehicle Velocity Local Horizontal) with the Z-axis flipped.

            // Z along the position
            zBasis = updateTransformCartesian3Scratch2;
            Cartesian3.normalize(inertialCartesian, zBasis);
            Cartesian3.normalize(inertialDeltaCartesian, inertialDeltaCartesian);

            // Y is along the angular momentum vector (e.g. "orbit normal")
            yBasis = Cartesian3.cross(
              zBasis,
              inertialDeltaCartesian,
              updateTransformCartesian3Scratch3
            );

            if (invertVelocity) {
              yBasis = Cartesian3.multiplyByScalar(yBasis, -1, yBasis);
            }

            if (
              !Cartesian3.equalsEpsilon(
                yBasis,
                Cartesian3.ZERO,
                CesiumMath.EPSILON7
              )
            ) {
              // X is along the cross of y and z (right handed basis / in the direction of motion)
              xBasis = Cartesian3.cross(
                yBasis,
                zBasis,
                updateTransformCartesian3Scratch1
              );

              Matrix3.multiplyByVector(toFixed, xBasis, xBasis);
              Matrix3.multiplyByVector(toFixed, yBasis, yBasis);
              Matrix3.multiplyByVector(toFixed, zBasis, zBasis);

              Cartesian3.normalize(xBasis, xBasis);
              Cartesian3.normalize(yBasis, yBasis);
              Cartesian3.normalize(zBasis, zBasis);

              hasBasis = true;
            }
          }
        }
      }

      if (defined(that.boundingSphere)) {
        cartesian = that.boundingSphere.center;
      }

      var position;
      var direction;
      var up;

      if (saveCamera) {
        position = Cartesian3.clone(
          camera.position,
          updateTransformCartesian3Scratch4
        );
        direction = Cartesian3.clone(
          camera.direction,
          updateTransformCartesian3Scratch5
        );
        up = Cartesian3.clone(camera.up, updateTransformCartesian3Scratch6);
      }

      var transform = updateTransformMatrix4Scratch;
      if (hasBasis) {
        transform[0] = xBasis.x;
        transform[1] = xBasis.y;
        transform[2] = xBasis.z;
        transform[3] = 0.0;
        transform[4] = yBasis.x;
        transform[5] = yBasis.y;
        transform[6] = yBasis.z;
        transform[7] = 0.0;
        transform[8] = zBasis.x;
        transform[9] = zBasis.y;
        transform[10] = zBasis.z;
        transform[11] = 0.0;
        transform[12] = cartesian.x;
        transform[13] = cartesian.y;
        transform[14] = cartesian.z;
        transform[15] = 0.0;
      } else {
        // Stationary or slow-moving, low-altitude objects use East-North-Up.
        Transforms.eastNorthUpToFixedFrame(cartesian, ellipsoid, transform);
      }

      camera._setTransform(transform);

      if (saveCamera) {
        Cartesian3.clone(position, camera.position);
        Cartesian3.clone(direction, camera.direction);
        Cartesian3.clone(up, camera.up);
        Cartesian3.cross(direction, up, camera.right);
      }
    }

    if (updateLookAt) {
      var offset =
        mode === SceneMode$1.SCENE2D ||
        Cartesian3.equals(that._offset3D, Cartesian3.ZERO)
          ? undefined
          : that._offset3D;
      camera.lookAtTransform(camera.transform, offset);
    }
  }

  /**
   * A utility object for tracking an entity with the camera.
   * @alias EntityView
   * @constructor
   *
   * @param {Entity} entity The entity to track with the camera.
   * @param {Scene} scene The scene to use.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid to use for orienting the camera.
   */
  function EntityView(entity, scene, ellipsoid) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("entity", entity);
    Check.defined("scene", scene);
    //>>includeEnd('debug');

    /**
     * The entity to track with the camera.
     * @type {Entity}
     */
    this.entity = entity;

    /**
     * The scene in which to track the object.
     * @type {Scene}
     */
    this.scene = scene;

    /**
     * The ellipsoid to use for orienting the camera.
     * @type {Ellipsoid}
     */
    this.ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    /**
     * The bounding sphere of the object.
     * @type {BoundingSphere}
     */
    this.boundingSphere = undefined;

    // Shadow copies of the objects so we can detect changes.
    this._lastEntity = undefined;
    this._mode = undefined;

    this._lastCartesian = new Cartesian3();
    this._defaultOffset3D = undefined;

    this._offset3D = new Cartesian3();
  }

  // STATIC properties defined here, not per-instance.
  Object.defineProperties(EntityView, {
    /**
     * Gets or sets a camera offset that will be used to
     * initialize subsequent EntityViews.
     * @memberof EntityView
     * @type {Cartesian3}
     */
    defaultOffset3D: {
      get: function () {
        return this._defaultOffset3D;
      },
      set: function (vector) {
        this._defaultOffset3D = Cartesian3.clone(vector, new Cartesian3());
      },
    },
  });

  // Initialize the static property.
  EntityView.defaultOffset3D = new Cartesian3(-14000, 3500, 3500);

  var scratchHeadingPitchRange = new HeadingPitchRange();
  var scratchCartesian$7 = new Cartesian3();

  /**
   * Should be called each animation frame to update the camera
   * to the latest settings.
   * @param {JulianDate} time The current animation time.
   * @param {BoundingSphere} [boundingSphere] bounding sphere of the object.
   */
  EntityView.prototype.update = function (time, boundingSphere) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("time", time);
    //>>includeEnd('debug');

    var scene = this.scene;
    var ellipsoid = this.ellipsoid;
    var sceneMode = scene.mode;
    if (sceneMode === SceneMode$1.MORPHING) {
      return;
    }

    var entity = this.entity;
    var positionProperty = entity.position;
    if (!defined(positionProperty)) {
      return;
    }
    var objectChanged = entity !== this._lastEntity;
    var sceneModeChanged = sceneMode !== this._mode;

    var camera = scene.camera;

    var updateLookAt = objectChanged || sceneModeChanged;
    var saveCamera = true;

    if (objectChanged) {
      var viewFromProperty = entity.viewFrom;
      var hasViewFrom = defined(viewFromProperty);

      if (!hasViewFrom && defined(boundingSphere)) {
        // The default HPR is not ideal for high altitude objects so
        // we scale the pitch as we get further from the earth for a more
        // downward view.
        scratchHeadingPitchRange.pitch = -CesiumMath.PI_OVER_FOUR;
        scratchHeadingPitchRange.range = 0;
        var position = positionProperty.getValue(time, scratchCartesian$7);
        if (defined(position)) {
          var factor =
            2 -
            1 /
              Math.max(
                1,
                Cartesian3.magnitude(position) / ellipsoid.maximumRadius
              );
          scratchHeadingPitchRange.pitch *= factor;
        }

        camera.viewBoundingSphere(boundingSphere, scratchHeadingPitchRange);
        this.boundingSphere = boundingSphere;
        updateLookAt = false;
        saveCamera = false;
      } else if (
        !hasViewFrom ||
        !defined(viewFromProperty.getValue(time, this._offset3D))
      ) {
        Cartesian3.clone(EntityView._defaultOffset3D, this._offset3D);
      }
    } else if (!sceneModeChanged && this._mode !== SceneMode$1.SCENE2D) {
      Cartesian3.clone(camera.position, this._offset3D);
    }

    this._lastEntity = entity;
    this._mode = sceneMode;

    updateTransform(
      this,
      camera,
      updateLookAt,
      saveCamera,
      positionProperty,
      time,
      ellipsoid
    );
  };

  /**
  @license
  topojson - https://github.com/topojson/topojson

  Copyright (c) 2012-2016, Michael Bostock
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.

  * Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

  * The name Michael Bostock may not be used to endorse or promote products
    derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL MICHAEL BOSTOCK BE LIABLE FOR ANY DIRECT,
  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  **/

  var tmp$3 = {};

  // https://github.com/topojson/topojson Version 3.0.2. Copyright 2017 Mike Bostock.
  (function (global, factory) {
  	typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
  	(factory((global.topojson = global.topojson || {})));
  }(tmp$3, (function (exports) {
  var identity = function(x) {
    return x;
  };

  var transform = function(transform) {
    if (transform == null) return identity;
    var x0,
        y0,
        kx = transform.scale[0],
        ky = transform.scale[1],
        dx = transform.translate[0],
        dy = transform.translate[1];
    return function(input, i) {
      if (!i) x0 = y0 = 0;
      var j = 2, n = input.length, output = new Array(n);
      output[0] = (x0 += input[0]) * kx + dx;
      output[1] = (y0 += input[1]) * ky + dy;
      while (j < n) output[j] = input[j], ++j;
      return output;
    };
  };

  var bbox = function(topology) {
    var t = transform(topology.transform), key,
        x0 = Infinity, y0 = x0, x1 = -x0, y1 = -x0;

    function bboxPoint(p) {
      p = t(p);
      if (p[0] < x0) x0 = p[0];
      if (p[0] > x1) x1 = p[0];
      if (p[1] < y0) y0 = p[1];
      if (p[1] > y1) y1 = p[1];
    }

    function bboxGeometry(o) {
      switch (o.type) {
        case "GeometryCollection": o.geometries.forEach(bboxGeometry); break;
        case "Point": bboxPoint(o.coordinates); break;
        case "MultiPoint": o.coordinates.forEach(bboxPoint); break;
      }
    }

    topology.arcs.forEach(function(arc) {
      var i = -1, n = arc.length, p;
      while (++i < n) {
        p = t(arc[i], i);
        if (p[0] < x0) x0 = p[0];
        if (p[0] > x1) x1 = p[0];
        if (p[1] < y0) y0 = p[1];
        if (p[1] > y1) y1 = p[1];
      }
    });

    for (key in topology.objects) {
      bboxGeometry(topology.objects[key]);
    }

    return [x0, y0, x1, y1];
  };

  var reverse = function(array, n) {
    var t, j = array.length, i = j - n;
    while (i < --j) t = array[i], array[i++] = array[j], array[j] = t;
  };

  var feature = function(topology, o) {
    return o.type === "GeometryCollection"
        ? {type: "FeatureCollection", features: o.geometries.map(function(o) { return feature$1(topology, o); })}
        : feature$1(topology, o);
  };

  function feature$1(topology, o) {
    var id = o.id,
        bbox = o.bbox,
        properties = o.properties == null ? {} : o.properties,
        geometry = object(topology, o);
    return id == null && bbox == null ? {type: "Feature", properties: properties, geometry: geometry}
        : bbox == null ? {type: "Feature", id: id, properties: properties, geometry: geometry}
        : {type: "Feature", id: id, bbox: bbox, properties: properties, geometry: geometry};
  }

  function object(topology, o) {
    var transformPoint = transform(topology.transform),
        arcs = topology.arcs;

    function arc(i, points) {
      if (points.length) points.pop();
      for (var a = arcs[i < 0 ? ~i : i], k = 0, n = a.length; k < n; ++k) {
        points.push(transformPoint(a[k], k));
      }
      if (i < 0) reverse(points, n);
    }

    function point(p) {
      return transformPoint(p);
    }

    function line(arcs) {
      var points = [];
      for (var i = 0, n = arcs.length; i < n; ++i) arc(arcs[i], points);
      if (points.length < 2) points.push(points[0]); // This should never happen per the specification.
      return points;
    }

    function ring(arcs) {
      var points = line(arcs);
      while (points.length < 4) points.push(points[0]); // This may happen if an arc has only two points.
      return points;
    }

    function polygon(arcs) {
      return arcs.map(ring);
    }

    function geometry(o) {
      var type = o.type, coordinates;
      switch (type) {
        case "GeometryCollection": return {type: type, geometries: o.geometries.map(geometry)};
        case "Point": coordinates = point(o.coordinates); break;
        case "MultiPoint": coordinates = o.coordinates.map(point); break;
        case "LineString": coordinates = line(o.arcs); break;
        case "MultiLineString": coordinates = o.arcs.map(line); break;
        case "Polygon": coordinates = polygon(o.arcs); break;
        case "MultiPolygon": coordinates = o.arcs.map(polygon); break;
        default: return null;
      }
      return {type: type, coordinates: coordinates};
    }

    return geometry(o);
  }

  var stitch = function(topology, arcs) {
    var stitchedArcs = {},
        fragmentByStart = {},
        fragmentByEnd = {},
        fragments = [],
        emptyIndex = -1;

    // Stitch empty arcs first, since they may be subsumed by other arcs.
    arcs.forEach(function(i, j) {
      var arc = topology.arcs[i < 0 ? ~i : i], t;
      if (arc.length < 3 && !arc[1][0] && !arc[1][1]) {
        t = arcs[++emptyIndex], arcs[emptyIndex] = i, arcs[j] = t;
      }
    });

    arcs.forEach(function(i) {
      var e = ends(i),
          start = e[0],
          end = e[1],
          f, g;

      if (f = fragmentByEnd[start]) {
        delete fragmentByEnd[f.end];
        f.push(i);
        f.end = end;
        if (g = fragmentByStart[end]) {
          delete fragmentByStart[g.start];
          var fg = g === f ? f : f.concat(g);
          fragmentByStart[fg.start = f.start] = fragmentByEnd[fg.end = g.end] = fg;
        } else {
          fragmentByStart[f.start] = fragmentByEnd[f.end] = f;
        }
      } else if (f = fragmentByStart[end]) {
        delete fragmentByStart[f.start];
        f.unshift(i);
        f.start = start;
        if (g = fragmentByEnd[start]) {
          delete fragmentByEnd[g.end];
          var gf = g === f ? f : g.concat(f);
          fragmentByStart[gf.start = g.start] = fragmentByEnd[gf.end = f.end] = gf;
        } else {
          fragmentByStart[f.start] = fragmentByEnd[f.end] = f;
        }
      } else {
        f = [i];
        fragmentByStart[f.start = start] = fragmentByEnd[f.end = end] = f;
      }
    });

    function ends(i) {
      var arc = topology.arcs[i < 0 ? ~i : i], p0 = arc[0], p1;
      if (topology.transform) p1 = [0, 0], arc.forEach(function(dp) { p1[0] += dp[0], p1[1] += dp[1]; });
      else p1 = arc[arc.length - 1];
      return i < 0 ? [p1, p0] : [p0, p1];
    }

    function flush(fragmentByEnd, fragmentByStart) {
      for (var k in fragmentByEnd) {
        var f = fragmentByEnd[k];
        delete fragmentByStart[f.start];
        delete f.start;
        delete f.end;
        f.forEach(function(i) { stitchedArcs[i < 0 ? ~i : i] = 1; });
        fragments.push(f);
      }
    }

    flush(fragmentByEnd, fragmentByStart);
    flush(fragmentByStart, fragmentByEnd);
    arcs.forEach(function(i) { if (!stitchedArcs[i < 0 ? ~i : i]) fragments.push([i]); });

    return fragments;
  };

  var mesh = function(topology) {
    return object(topology, meshArcs.apply(this, arguments));
  };

  function meshArcs(topology, object$$1, filter) {
    var arcs, i, n;
    if (arguments.length > 1) arcs = extractArcs(topology, object$$1, filter);
    else for (i = 0, arcs = new Array(n = topology.arcs.length); i < n; ++i) arcs[i] = i;
    return {type: "MultiLineString", arcs: stitch(topology, arcs)};
  }

  function extractArcs(topology, object$$1, filter) {
    var arcs = [],
        geomsByArc = [],
        geom;

    function extract0(i) {
      var j = i < 0 ? ~i : i;
      (geomsByArc[j] || (geomsByArc[j] = [])).push({i: i, g: geom});
    }

    function extract1(arcs) {
      arcs.forEach(extract0);
    }

    function extract2(arcs) {
      arcs.forEach(extract1);
    }

    function extract3(arcs) {
      arcs.forEach(extract2);
    }

    function geometry(o) {
      switch (geom = o, o.type) {
        case "GeometryCollection": o.geometries.forEach(geometry); break;
        case "LineString": extract1(o.arcs); break;
        case "MultiLineString": case "Polygon": extract2(o.arcs); break;
        case "MultiPolygon": extract3(o.arcs); break;
      }
    }

    geometry(object$$1);

    geomsByArc.forEach(filter == null
        ? function(geoms) { arcs.push(geoms[0].i); }
        : function(geoms) { if (filter(geoms[0].g, geoms[geoms.length - 1].g)) arcs.push(geoms[0].i); });

    return arcs;
  }

  function planarRingArea(ring) {
    var i = -1, n = ring.length, a, b = ring[n - 1], area = 0;
    while (++i < n) a = b, b = ring[i], area += a[0] * b[1] - a[1] * b[0];
    return Math.abs(area); // Note: doubled area!
  }

  var merge = function(topology) {
    return object(topology, mergeArcs.apply(this, arguments));
  };

  function mergeArcs(topology, objects) {
    var polygonsByArc = {},
        polygons = [],
        groups = [];

    objects.forEach(geometry);

    function geometry(o) {
      switch (o.type) {
        case "GeometryCollection": o.geometries.forEach(geometry); break;
        case "Polygon": extract(o.arcs); break;
        case "MultiPolygon": o.arcs.forEach(extract); break;
      }
    }

    function extract(polygon) {
      polygon.forEach(function(ring) {
        ring.forEach(function(arc) {
          (polygonsByArc[arc = arc < 0 ? ~arc : arc] || (polygonsByArc[arc] = [])).push(polygon);
        });
      });
      polygons.push(polygon);
    }

    function area(ring) {
      return planarRingArea(object(topology, {type: "Polygon", arcs: [ring]}).coordinates[0]);
    }

    polygons.forEach(function(polygon) {
      if (!polygon._) {
        var group = [],
            neighbors = [polygon];
        polygon._ = 1;
        groups.push(group);
        while (polygon = neighbors.pop()) {
          group.push(polygon);
          polygon.forEach(function(ring) {
            ring.forEach(function(arc) {
              polygonsByArc[arc < 0 ? ~arc : arc].forEach(function(polygon) {
                if (!polygon._) {
                  polygon._ = 1;
                  neighbors.push(polygon);
                }
              });
            });
          });
        }
      }
    });

    polygons.forEach(function(polygon) {
      delete polygon._;
    });

    return {
      type: "MultiPolygon",
      arcs: groups.map(function(polygons) {
        var arcs = [], n;

        // Extract the exterior (unique) arcs.
        polygons.forEach(function(polygon) {
          polygon.forEach(function(ring) {
            ring.forEach(function(arc) {
              if (polygonsByArc[arc < 0 ? ~arc : arc].length < 2) {
                arcs.push(arc);
              }
            });
          });
        });

        // Stitch the arcs into one or more rings.
        arcs = stitch(topology, arcs);

        // If more than one ring is returned,
        // at most one of these rings can be the exterior;
        // choose the one with the greatest absolute area.
        if ((n = arcs.length) > 1) {
          for (var i = 1, k = area(arcs[0]), ki, t; i < n; ++i) {
            if ((ki = area(arcs[i])) > k) {
              t = arcs[0], arcs[0] = arcs[i], arcs[i] = t, k = ki;
            }
          }
        }

        return arcs;
      })
    };
  }

  var bisect = function(a, x) {
    var lo = 0, hi = a.length;
    while (lo < hi) {
      var mid = lo + hi >>> 1;
      if (a[mid] < x) lo = mid + 1;
      else hi = mid;
    }
    return lo;
  };

  var neighbors = function(objects) {
    var indexesByArc = {}, // arc index -> array of object indexes
        neighbors = objects.map(function() { return []; });

    function line(arcs, i) {
      arcs.forEach(function(a) {
        if (a < 0) a = ~a;
        var o = indexesByArc[a];
        if (o) o.push(i);
        else indexesByArc[a] = [i];
      });
    }

    function polygon(arcs, i) {
      arcs.forEach(function(arc) { line(arc, i); });
    }

    function geometry(o, i) {
      if (o.type === "GeometryCollection") o.geometries.forEach(function(o) { geometry(o, i); });
      else if (o.type in geometryType) geometryType[o.type](o.arcs, i);
    }

    var geometryType = {
      LineString: line,
      MultiLineString: polygon,
      Polygon: polygon,
      MultiPolygon: function(arcs, i) { arcs.forEach(function(arc) { polygon(arc, i); }); }
    };

    objects.forEach(geometry);

    for (var i in indexesByArc) {
      for (var indexes = indexesByArc[i], m = indexes.length, j = 0; j < m; ++j) {
        for (var k = j + 1; k < m; ++k) {
          var ij = indexes[j], ik = indexes[k], n;
          if ((n = neighbors[ij])[i = bisect(n, ik)] !== ik) n.splice(i, 0, ik);
          if ((n = neighbors[ik])[i = bisect(n, ij)] !== ij) n.splice(i, 0, ij);
        }
      }
    }

    return neighbors;
  };

  var untransform = function(transform) {
    if (transform == null) return identity;
    var x0,
        y0,
        kx = transform.scale[0],
        ky = transform.scale[1],
        dx = transform.translate[0],
        dy = transform.translate[1];
    return function(input, i) {
      if (!i) x0 = y0 = 0;
      var j = 2,
          n = input.length,
          output = new Array(n),
          x1 = Math.round((input[0] - dx) / kx),
          y1 = Math.round((input[1] - dy) / ky);
      output[0] = x1 - x0, x0 = x1;
      output[1] = y1 - y0, y0 = y1;
      while (j < n) output[j] = input[j], ++j;
      return output;
    };
  };

  var quantize = function(topology, transform) {
    if (topology.transform) throw new Error("already quantized");

    if (!transform || !transform.scale) {
      if (!((n = Math.floor(transform)) >= 2)) throw new Error("n must be \u22652");
      box = topology.bbox || bbox(topology);
      var x0 = box[0], y0 = box[1], x1 = box[2], y1 = box[3], n;
      transform = {scale: [x1 - x0 ? (x1 - x0) / (n - 1) : 1, y1 - y0 ? (y1 - y0) / (n - 1) : 1], translate: [x0, y0]};
    } else {
      box = topology.bbox;
    }

    var t = untransform(transform), box, key, inputs = topology.objects, outputs = {};

    function quantizePoint(point) {
      return t(point);
    }

    function quantizeGeometry(input) {
      var output;
      switch (input.type) {
        case "GeometryCollection": output = {type: "GeometryCollection", geometries: input.geometries.map(quantizeGeometry)}; break;
        case "Point": output = {type: "Point", coordinates: quantizePoint(input.coordinates)}; break;
        case "MultiPoint": output = {type: "MultiPoint", coordinates: input.coordinates.map(quantizePoint)}; break;
        default: return input;
      }
      if (input.id != null) output.id = input.id;
      if (input.bbox != null) output.bbox = input.bbox;
      if (input.properties != null) output.properties = input.properties;
      return output;
    }

    function quantizeArc(input) {
      var i = 0, j = 1, n = input.length, p, output = new Array(n); // pessimistic
      output[0] = t(input[0], 0);
      while (++i < n) if ((p = t(input[i], i))[0] || p[1]) output[j++] = p; // non-coincident points
      if (j === 1) output[j++] = [0, 0]; // an arc must have at least two points
      output.length = j;
      return output;
    }

    for (key in inputs) outputs[key] = quantizeGeometry(inputs[key]);

    return {
      type: "Topology",
      bbox: box,
      transform: transform,
      objects: outputs,
      arcs: topology.arcs.map(quantizeArc)
    };
  };

  // Computes the bounding box of the specified hash of GeoJSON objects.
  var bounds = function(objects) {
    var x0 = Infinity,
        y0 = Infinity,
        x1 = -Infinity,
        y1 = -Infinity;

    function boundGeometry(geometry) {
      if (geometry != null && boundGeometryType.hasOwnProperty(geometry.type)) boundGeometryType[geometry.type](geometry);
    }

    var boundGeometryType = {
      GeometryCollection: function(o) { o.geometries.forEach(boundGeometry); },
      Point: function(o) { boundPoint(o.coordinates); },
      MultiPoint: function(o) { o.coordinates.forEach(boundPoint); },
      LineString: function(o) { boundLine(o.arcs); },
      MultiLineString: function(o) { o.arcs.forEach(boundLine); },
      Polygon: function(o) { o.arcs.forEach(boundLine); },
      MultiPolygon: function(o) { o.arcs.forEach(boundMultiLine); }
    };

    function boundPoint(coordinates) {
      var x = coordinates[0],
          y = coordinates[1];
      if (x < x0) x0 = x;
      if (x > x1) x1 = x;
      if (y < y0) y0 = y;
      if (y > y1) y1 = y;
    }

    function boundLine(coordinates) {
      coordinates.forEach(boundPoint);
    }

    function boundMultiLine(coordinates) {
      coordinates.forEach(boundLine);
    }

    for (var key in objects) {
      boundGeometry(objects[key]);
    }

    return x1 >= x0 && y1 >= y0 ? [x0, y0, x1, y1] : undefined;
  };

  var hashset = function(size, hash, equal, type, empty) {
    if (arguments.length === 3) {
      type = Array;
      empty = null;
    }

    var store = new type(size = 1 << Math.max(4, Math.ceil(Math.log(size) / Math.LN2))),
        mask = size - 1;

    for (var i = 0; i < size; ++i) {
      store[i] = empty;
    }

    function add(value) {
      var index = hash(value) & mask,
          match = store[index],
          collisions = 0;
      while (match != empty) {
        if (equal(match, value)) return true;
        if (++collisions >= size) throw new Error("full hashset");
        match = store[index = (index + 1) & mask];
      }
      store[index] = value;
      return true;
    }

    function has(value) {
      var index = hash(value) & mask,
          match = store[index],
          collisions = 0;
      while (match != empty) {
        if (equal(match, value)) return true;
        if (++collisions >= size) break;
        match = store[index = (index + 1) & mask];
      }
      return false;
    }

    function values() {
      var values = [];
      for (var i = 0, n = store.length; i < n; ++i) {
        var match = store[i];
        if (match != empty) values.push(match);
      }
      return values;
    }

    return {
      add: add,
      has: has,
      values: values
    };
  };

  var hashmap = function(size, hash, equal, keyType, keyEmpty, valueType) {
    if (arguments.length === 3) {
      keyType = valueType = Array;
      keyEmpty = null;
    }

    var keystore = new keyType(size = 1 << Math.max(4, Math.ceil(Math.log(size) / Math.LN2))),
        valstore = new valueType(size),
        mask = size - 1;

    for (var i = 0; i < size; ++i) {
      keystore[i] = keyEmpty;
    }

    function set(key, value) {
      var index = hash(key) & mask,
          matchKey = keystore[index],
          collisions = 0;
      while (matchKey != keyEmpty) {
        if (equal(matchKey, key)) return valstore[index] = value;
        if (++collisions >= size) throw new Error("full hashmap");
        matchKey = keystore[index = (index + 1) & mask];
      }
      keystore[index] = key;
      valstore[index] = value;
      return value;
    }

    function maybeSet(key, value) {
      var index = hash(key) & mask,
          matchKey = keystore[index],
          collisions = 0;
      while (matchKey != keyEmpty) {
        if (equal(matchKey, key)) return valstore[index];
        if (++collisions >= size) throw new Error("full hashmap");
        matchKey = keystore[index = (index + 1) & mask];
      }
      keystore[index] = key;
      valstore[index] = value;
      return value;
    }

    function get(key, missingValue) {
      var index = hash(key) & mask,
          matchKey = keystore[index],
          collisions = 0;
      while (matchKey != keyEmpty) {
        if (equal(matchKey, key)) return valstore[index];
        if (++collisions >= size) break;
        matchKey = keystore[index = (index + 1) & mask];
      }
      return missingValue;
    }

    function keys() {
      var keys = [];
      for (var i = 0, n = keystore.length; i < n; ++i) {
        var matchKey = keystore[i];
        if (matchKey != keyEmpty) keys.push(matchKey);
      }
      return keys;
    }

    return {
      set: set,
      maybeSet: maybeSet, // set if unset
      get: get,
      keys: keys
    };
  };

  var equalPoint = function(pointA, pointB) {
    return pointA[0] === pointB[0] && pointA[1] === pointB[1];
  };

  // TODO if quantized, use simpler Int32 hashing?

  var buffer = new ArrayBuffer(16);
  var uints = new Uint32Array(buffer);

  var hashPoint = function(point) {
    var hash = uints[0] ^ uints[1];
    hash = hash << 5 ^ hash >> 7 ^ uints[2] ^ uints[3];
    return hash & 0x7fffffff;
  };

  // Given an extracted (pre-)topology, identifies all of the junctions. These are
  // the points at which arcs (lines or rings) will need to be cut so that each
  // arc is represented uniquely.
  //
  // A junction is a point where at least one arc deviates from another arc going
  // through the same point. For example, consider the point B. If there is a arc
  // through ABC and another arc through CBA, then B is not a junction because in
  // both cases the adjacent point pairs are {A,C}. However, if there is an
  // additional arc ABD, then {A,D} != {A,C}, and thus B becomes a junction.
  //
  // For a closed ring ABCA, the first point A’s adjacent points are the second
  // and last point {B,C}. For a line, the first and last point are always
  // considered junctions, even if the line is closed; this ensures that a closed
  // line is never rotated.
  var join = function(topology) {
    var coordinates = topology.coordinates,
        lines = topology.lines,
        rings = topology.rings,
        indexes = index(),
        visitedByIndex = new Int32Array(coordinates.length),
        leftByIndex = new Int32Array(coordinates.length),
        rightByIndex = new Int32Array(coordinates.length),
        junctionByIndex = new Int8Array(coordinates.length),
        junctionCount = 0, // upper bound on number of junctions
        i, n,
        previousIndex,
        currentIndex,
        nextIndex;

    for (i = 0, n = coordinates.length; i < n; ++i) {
      visitedByIndex[i] = leftByIndex[i] = rightByIndex[i] = -1;
    }

    for (i = 0, n = lines.length; i < n; ++i) {
      var line = lines[i],
          lineStart = line[0],
          lineEnd = line[1];
      currentIndex = indexes[lineStart];
      nextIndex = indexes[++lineStart];
      ++junctionCount, junctionByIndex[currentIndex] = 1; // start
      while (++lineStart <= lineEnd) {
        sequence(i, previousIndex = currentIndex, currentIndex = nextIndex, nextIndex = indexes[lineStart]);
      }
      ++junctionCount, junctionByIndex[nextIndex] = 1; // end
    }

    for (i = 0, n = coordinates.length; i < n; ++i) {
      visitedByIndex[i] = -1;
    }

    for (i = 0, n = rings.length; i < n; ++i) {
      var ring = rings[i],
          ringStart = ring[0] + 1,
          ringEnd = ring[1];
      previousIndex = indexes[ringEnd - 1];
      currentIndex = indexes[ringStart - 1];
      nextIndex = indexes[ringStart];
      sequence(i, previousIndex, currentIndex, nextIndex);
      while (++ringStart <= ringEnd) {
        sequence(i, previousIndex = currentIndex, currentIndex = nextIndex, nextIndex = indexes[ringStart]);
      }
    }

    function sequence(i, previousIndex, currentIndex, nextIndex) {
      if (visitedByIndex[currentIndex] === i) return; // ignore self-intersection
      visitedByIndex[currentIndex] = i;
      var leftIndex = leftByIndex[currentIndex];
      if (leftIndex >= 0) {
        var rightIndex = rightByIndex[currentIndex];
        if ((leftIndex !== previousIndex || rightIndex !== nextIndex)
          && (leftIndex !== nextIndex || rightIndex !== previousIndex)) {
          ++junctionCount, junctionByIndex[currentIndex] = 1;
        }
      } else {
        leftByIndex[currentIndex] = previousIndex;
        rightByIndex[currentIndex] = nextIndex;
      }
    }

    function index() {
      var indexByPoint = hashmap(coordinates.length * 1.4, hashIndex, equalIndex, Int32Array, -1, Int32Array),
          indexes = new Int32Array(coordinates.length);

      for (var i = 0, n = coordinates.length; i < n; ++i) {
        indexes[i] = indexByPoint.maybeSet(i, i);
      }

      return indexes;
    }

    function hashIndex(i) {
      return hashPoint(coordinates[i]);
    }

    function equalIndex(i, j) {
      return equalPoint(coordinates[i], coordinates[j]);
    }

    visitedByIndex = leftByIndex = rightByIndex = null;

    var junctionByPoint = hashset(junctionCount * 1.4, hashPoint, equalPoint), j;

    // Convert back to a standard hashset by point for caller convenience.
    for (i = 0, n = coordinates.length; i < n; ++i) {
      if (junctionByIndex[j = indexes[i]]) {
        junctionByPoint.add(coordinates[j]);
      }
    }

    return junctionByPoint;
  };

  // Given an extracted (pre-)topology, cuts (or rotates) arcs so that all shared
  // point sequences are identified. The topology can then be subsequently deduped
  // to remove exact duplicate arcs.
  var cut = function(topology) {
    var junctions = join(topology),
        coordinates = topology.coordinates,
        lines = topology.lines,
        rings = topology.rings,
        next,
        i, n;

    for (i = 0, n = lines.length; i < n; ++i) {
      var line = lines[i],
          lineMid = line[0],
          lineEnd = line[1];
      while (++lineMid < lineEnd) {
        if (junctions.has(coordinates[lineMid])) {
          next = {0: lineMid, 1: line[1]};
          line[1] = lineMid;
          line = line.next = next;
        }
      }
    }

    for (i = 0, n = rings.length; i < n; ++i) {
      var ring = rings[i],
          ringStart = ring[0],
          ringMid = ringStart,
          ringEnd = ring[1],
          ringFixed = junctions.has(coordinates[ringStart]);
      while (++ringMid < ringEnd) {
        if (junctions.has(coordinates[ringMid])) {
          if (ringFixed) {
            next = {0: ringMid, 1: ring[1]};
            ring[1] = ringMid;
            ring = ring.next = next;
          } else { // For the first junction, we can rotate rather than cut.
            rotateArray(coordinates, ringStart, ringEnd, ringEnd - ringMid);
            coordinates[ringEnd] = coordinates[ringStart];
            ringFixed = true;
            ringMid = ringStart; // restart; we may have skipped junctions
          }
        }
      }
    }

    return topology;
  };

  function rotateArray(array, start, end, offset) {
    reverse$1(array, start, end);
    reverse$1(array, start, start + offset);
    reverse$1(array, start + offset, end);
  }

  function reverse$1(array, start, end) {
    for (var mid = start + ((end-- - start) >> 1), t; start < mid; ++start, --end) {
      t = array[start], array[start] = array[end], array[end] = t;
    }
  }

  // Given a cut topology, combines duplicate arcs.
  var dedup = function(topology) {
    var coordinates = topology.coordinates,
        lines = topology.lines, line,
        rings = topology.rings, ring,
        arcCount = lines.length + rings.length,
        i, n;

    delete topology.lines;
    delete topology.rings;

    // Count the number of (non-unique) arcs to initialize the hashmap safely.
    for (i = 0, n = lines.length; i < n; ++i) {
      line = lines[i]; while (line = line.next) ++arcCount;
    }
    for (i = 0, n = rings.length; i < n; ++i) {
      ring = rings[i]; while (ring = ring.next) ++arcCount;
    }

    var arcsByEnd = hashmap(arcCount * 2 * 1.4, hashPoint, equalPoint),
        arcs = topology.arcs = [];

    for (i = 0, n = lines.length; i < n; ++i) {
      line = lines[i];
      do {
        dedupLine(line);
      } while (line = line.next);
    }

    for (i = 0, n = rings.length; i < n; ++i) {
      ring = rings[i];
      if (ring.next) { // arc is no longer closed
        do {
          dedupLine(ring);
        } while (ring = ring.next);
      } else {
        dedupRing(ring);
      }
    }

    function dedupLine(arc) {
      var startPoint,
          endPoint,
          startArcs, startArc,
          endArcs, endArc,
          i, n;

      // Does this arc match an existing arc in order?
      if (startArcs = arcsByEnd.get(startPoint = coordinates[arc[0]])) {
        for (i = 0, n = startArcs.length; i < n; ++i) {
          startArc = startArcs[i];
          if (equalLine(startArc, arc)) {
            arc[0] = startArc[0];
            arc[1] = startArc[1];
            return;
          }
        }
      }

      // Does this arc match an existing arc in reverse order?
      if (endArcs = arcsByEnd.get(endPoint = coordinates[arc[1]])) {
        for (i = 0, n = endArcs.length; i < n; ++i) {
          endArc = endArcs[i];
          if (reverseEqualLine(endArc, arc)) {
            arc[1] = endArc[0];
            arc[0] = endArc[1];
            return;
          }
        }
      }

      if (startArcs) startArcs.push(arc); else arcsByEnd.set(startPoint, [arc]);
      if (endArcs) endArcs.push(arc); else arcsByEnd.set(endPoint, [arc]);
      arcs.push(arc);
    }

    function dedupRing(arc) {
      var endPoint,
          endArcs,
          endArc,
          i, n;

      // Does this arc match an existing line in order, or reverse order?
      // Rings are closed, so their start point and end point is the same.
      if (endArcs = arcsByEnd.get(endPoint = coordinates[arc[0]])) {
        for (i = 0, n = endArcs.length; i < n; ++i) {
          endArc = endArcs[i];
          if (equalRing(endArc, arc)) {
            arc[0] = endArc[0];
            arc[1] = endArc[1];
            return;
          }
          if (reverseEqualRing(endArc, arc)) {
            arc[0] = endArc[1];
            arc[1] = endArc[0];
            return;
          }
        }
      }

      // Otherwise, does this arc match an existing ring in order, or reverse order?
      if (endArcs = arcsByEnd.get(endPoint = coordinates[arc[0] + findMinimumOffset(arc)])) {
        for (i = 0, n = endArcs.length; i < n; ++i) {
          endArc = endArcs[i];
          if (equalRing(endArc, arc)) {
            arc[0] = endArc[0];
            arc[1] = endArc[1];
            return;
          }
          if (reverseEqualRing(endArc, arc)) {
            arc[0] = endArc[1];
            arc[1] = endArc[0];
            return;
          }
        }
      }

      if (endArcs) endArcs.push(arc); else arcsByEnd.set(endPoint, [arc]);
      arcs.push(arc);
    }

    function equalLine(arcA, arcB) {
      var ia = arcA[0], ib = arcB[0],
          ja = arcA[1], jb = arcB[1];
      if (ia - ja !== ib - jb) return false;
      for (; ia <= ja; ++ia, ++ib) if (!equalPoint(coordinates[ia], coordinates[ib])) return false;
      return true;
    }

    function reverseEqualLine(arcA, arcB) {
      var ia = arcA[0], ib = arcB[0],
          ja = arcA[1], jb = arcB[1];
      if (ia - ja !== ib - jb) return false;
      for (; ia <= ja; ++ia, --jb) if (!equalPoint(coordinates[ia], coordinates[jb])) return false;
      return true;
    }

    function equalRing(arcA, arcB) {
      var ia = arcA[0], ib = arcB[0],
          ja = arcA[1], jb = arcB[1],
          n = ja - ia;
      if (n !== jb - ib) return false;
      var ka = findMinimumOffset(arcA),
          kb = findMinimumOffset(arcB);
      for (var i = 0; i < n; ++i) {
        if (!equalPoint(coordinates[ia + (i + ka) % n], coordinates[ib + (i + kb) % n])) return false;
      }
      return true;
    }

    function reverseEqualRing(arcA, arcB) {
      var ia = arcA[0], ib = arcB[0],
          ja = arcA[1], jb = arcB[1],
          n = ja - ia;
      if (n !== jb - ib) return false;
      var ka = findMinimumOffset(arcA),
          kb = n - findMinimumOffset(arcB);
      for (var i = 0; i < n; ++i) {
        if (!equalPoint(coordinates[ia + (i + ka) % n], coordinates[jb - (i + kb) % n])) return false;
      }
      return true;
    }

    // Rings are rotated to a consistent, but arbitrary, start point.
    // This is necessary to detect when a ring and a rotated copy are dupes.
    function findMinimumOffset(arc) {
      var start = arc[0],
          end = arc[1],
          mid = start,
          minimum = mid,
          minimumPoint = coordinates[mid];
      while (++mid < end) {
        var point = coordinates[mid];
        if (point[0] < minimumPoint[0] || point[0] === minimumPoint[0] && point[1] < minimumPoint[1]) {
          minimum = mid;
          minimumPoint = point;
        }
      }
      return minimum - start;
    }

    return topology;
  };

  // Given an array of arcs in absolute (but already quantized!) coordinates,
  // converts to fixed-point delta encoding.
  // This is a destructive operation that modifies the given arcs!
  var delta = function(arcs) {
    var i = -1,
        n = arcs.length;

    while (++i < n) {
      var arc = arcs[i],
          j = 0,
          k = 1,
          m = arc.length,
          point = arc[0],
          x0 = point[0],
          y0 = point[1],
          x1,
          y1;

      while (++j < m) {
        point = arc[j], x1 = point[0], y1 = point[1];
        if (x1 !== x0 || y1 !== y0) arc[k++] = [x1 - x0, y1 - y0], x0 = x1, y0 = y1;
      }

      if (k === 1) arc[k++] = [0, 0]; // Each arc must be an array of two or more positions.

      arc.length = k;
    }

    return arcs;
  };

  // Extracts the lines and rings from the specified hash of geometry objects.
  //
  // Returns an object with three properties:
  //
  // * coordinates - shared buffer of [x, y] coordinates
  // * lines - lines extracted from the hash, of the form [start, end]
  // * rings - rings extracted from the hash, of the form [start, end]
  //
  // For each ring or line, start and end represent inclusive indexes into the
  // coordinates buffer. For rings (and closed lines), coordinates[start] equals
  // coordinates[end].
  //
  // For each line or polygon geometry in the input hash, including nested
  // geometries as in geometry collections, the `coordinates` array is replaced
  // with an equivalent `arcs` array that, for each line (for line string
  // geometries) or ring (for polygon geometries), points to one of the above
  // lines or rings.
  var extract = function(objects) {
    var index = -1,
        lines = [],
        rings = [],
        coordinates = [];

    function extractGeometry(geometry) {
      if (geometry && extractGeometryType.hasOwnProperty(geometry.type)) extractGeometryType[geometry.type](geometry);
    }

    var extractGeometryType = {
      GeometryCollection: function(o) { o.geometries.forEach(extractGeometry); },
      LineString: function(o) { o.arcs = extractLine(o.arcs); },
      MultiLineString: function(o) { o.arcs = o.arcs.map(extractLine); },
      Polygon: function(o) { o.arcs = o.arcs.map(extractRing); },
      MultiPolygon: function(o) { o.arcs = o.arcs.map(extractMultiRing); }
    };

    function extractLine(line) {
      for (var i = 0, n = line.length; i < n; ++i) coordinates[++index] = line[i];
      var arc = {0: index - n + 1, 1: index};
      lines.push(arc);
      return arc;
    }

    function extractRing(ring) {
      for (var i = 0, n = ring.length; i < n; ++i) coordinates[++index] = ring[i];
      var arc = {0: index - n + 1, 1: index};
      rings.push(arc);
      return arc;
    }

    function extractMultiRing(rings) {
      return rings.map(extractRing);
    }

    for (var key in objects) {
      extractGeometry(objects[key]);
    }

    return {
      type: "Topology",
      coordinates: coordinates,
      lines: lines,
      rings: rings,
      objects: objects
    };
  };

  // Given a hash of GeoJSON objects, returns a hash of GeoJSON geometry objects.
  // Any null input geometry objects are represented as {type: null} in the output.
  // Any feature.{id,properties,bbox} are transferred to the output geometry object.
  // Each output geometry object is a shallow copy of the input (e.g., properties, coordinates)!
  var geometry = function(inputs) {
    var outputs = {}, key;
    for (key in inputs) outputs[key] = geomifyObject(inputs[key]);
    return outputs;
  };

  function geomifyObject(input) {
    return input == null ? {type: null}
        : (input.type === "FeatureCollection" ? geomifyFeatureCollection
        : input.type === "Feature" ? geomifyFeature
        : geomifyGeometry)(input);
  }

  function geomifyFeatureCollection(input) {
    var output = {type: "GeometryCollection", geometries: input.features.map(geomifyFeature)};
    if (input.bbox != null) output.bbox = input.bbox;
    return output;
  }

  function geomifyFeature(input) {
    var output = geomifyGeometry(input.geometry), key; // eslint-disable-line no-unused-vars
    if (input.id != null) output.id = input.id;
    if (input.bbox != null) output.bbox = input.bbox;
    for (key in input.properties) { output.properties = input.properties; break; }
    return output;
  }

  function geomifyGeometry(input) {
    if (input == null) return {type: null};
    var output = input.type === "GeometryCollection" ? {type: "GeometryCollection", geometries: input.geometries.map(geomifyGeometry)}
        : input.type === "Point" || input.type === "MultiPoint" ? {type: input.type, coordinates: input.coordinates}
        : {type: input.type, arcs: input.coordinates}; // TODO Check for unknown types?
    if (input.bbox != null) output.bbox = input.bbox;
    return output;
  }

  var prequantize = function(objects, bbox, n) {
    var x0 = bbox[0],
        y0 = bbox[1],
        x1 = bbox[2],
        y1 = bbox[3],
        kx = x1 - x0 ? (n - 1) / (x1 - x0) : 1,
        ky = y1 - y0 ? (n - 1) / (y1 - y0) : 1;

    function quantizePoint(input) {
      return [Math.round((input[0] - x0) * kx), Math.round((input[1] - y0) * ky)];
    }

    function quantizePoints(input, m) {
      var i = -1,
          j = 0,
          n = input.length,
          output = new Array(n), // pessimistic
          pi,
          px,
          py,
          x,
          y;

      while (++i < n) {
        pi = input[i];
        x = Math.round((pi[0] - x0) * kx);
        y = Math.round((pi[1] - y0) * ky);
        if (x !== px || y !== py) output[j++] = [px = x, py = y]; // non-coincident points
      }

      output.length = j;
      while (j < m) j = output.push([output[0][0], output[0][1]]);
      return output;
    }

    function quantizeLine(input) {
      return quantizePoints(input, 2);
    }

    function quantizeRing(input) {
      return quantizePoints(input, 4);
    }

    function quantizePolygon(input) {
      return input.map(quantizeRing);
    }

    function quantizeGeometry(o) {
      if (o != null && quantizeGeometryType.hasOwnProperty(o.type)) quantizeGeometryType[o.type](o);
    }

    var quantizeGeometryType = {
      GeometryCollection: function(o) { o.geometries.forEach(quantizeGeometry); },
      Point: function(o) { o.coordinates = quantizePoint(o.coordinates); },
      MultiPoint: function(o) { o.coordinates = o.coordinates.map(quantizePoint); },
      LineString: function(o) { o.arcs = quantizeLine(o.arcs); },
      MultiLineString: function(o) { o.arcs = o.arcs.map(quantizeLine); },
      Polygon: function(o) { o.arcs = quantizePolygon(o.arcs); },
      MultiPolygon: function(o) { o.arcs = o.arcs.map(quantizePolygon); }
    };

    for (var key in objects) {
      quantizeGeometry(objects[key]);
    }

    return {
      scale: [1 / kx, 1 / ky],
      translate: [x0, y0]
    };
  };

  // Constructs the TopoJSON Topology for the specified hash of features.
  // Each object in the specified hash must be a GeoJSON object,
  // meaning FeatureCollection, a Feature or a geometry object.
  var topology = function(objects, quantization) {
    var bbox = bounds(objects = geometry(objects)),
        transform = quantization > 0 && bbox && prequantize(objects, bbox, quantization),
        topology = dedup(cut(extract(objects))),
        coordinates = topology.coordinates,
        indexByArc = hashmap(topology.arcs.length * 1.4, hashArc, equalArc);

    objects = topology.objects; // for garbage collection
    topology.bbox = bbox;
    topology.arcs = topology.arcs.map(function(arc, i) {
      indexByArc.set(arc, i);
      return coordinates.slice(arc[0], arc[1] + 1);
    });

    delete topology.coordinates;
    coordinates = null;

    function indexGeometry(geometry$$1) {
      if (geometry$$1 && indexGeometryType.hasOwnProperty(geometry$$1.type)) indexGeometryType[geometry$$1.type](geometry$$1);
    }

    var indexGeometryType = {
      GeometryCollection: function(o) { o.geometries.forEach(indexGeometry); },
      LineString: function(o) { o.arcs = indexArcs(o.arcs); },
      MultiLineString: function(o) { o.arcs = o.arcs.map(indexArcs); },
      Polygon: function(o) { o.arcs = o.arcs.map(indexArcs); },
      MultiPolygon: function(o) { o.arcs = o.arcs.map(indexMultiArcs); }
    };

    function indexArcs(arc) {
      var indexes = [];
      do {
        var index = indexByArc.get(arc);
        indexes.push(arc[0] < arc[1] ? index : ~index);
      } while (arc = arc.next);
      return indexes;
    }

    function indexMultiArcs(arcs) {
      return arcs.map(indexArcs);
    }

    for (var key in objects) {
      indexGeometry(objects[key]);
    }

    if (transform) {
      topology.transform = transform;
      topology.arcs = delta(topology.arcs);
    }

    return topology;
  };

  function hashArc(arc) {
    var i = arc[0], j = arc[1], t;
    if (j < i) t = i, i = j, j = t;
    return i + 31 * j;
  }

  function equalArc(arcA, arcB) {
    var ia = arcA[0], ja = arcA[1],
        ib = arcB[0], jb = arcB[1], t;
    if (ja < ia) t = ia, ia = ja, ja = t;
    if (jb < ib) t = ib, ib = jb, jb = t;
    return ia === ib && ja === jb;
  }

  var prune = function(topology) {
    var oldObjects = topology.objects,
        newObjects = {},
        oldArcs = topology.arcs,
        oldArcsLength = oldArcs.length,
        oldIndex = -1,
        newIndexByOldIndex = new Array(oldArcsLength),
        newArcsLength = 0,
        newArcs,
        newIndex = -1,
        key;

    function scanGeometry(input) {
      switch (input.type) {
        case "GeometryCollection": input.geometries.forEach(scanGeometry); break;
        case "LineString": scanArcs(input.arcs); break;
        case "MultiLineString": input.arcs.forEach(scanArcs); break;
        case "Polygon": input.arcs.forEach(scanArcs); break;
        case "MultiPolygon": input.arcs.forEach(scanMultiArcs); break;
      }
    }

    function scanArc(index) {
      if (index < 0) index = ~index;
      if (!newIndexByOldIndex[index]) newIndexByOldIndex[index] = 1, ++newArcsLength;
    }

    function scanArcs(arcs) {
      arcs.forEach(scanArc);
    }

    function scanMultiArcs(arcs) {
      arcs.forEach(scanArcs);
    }

    function reindexGeometry(input) {
      var output;
      switch (input.type) {
        case "GeometryCollection": output = {type: "GeometryCollection", geometries: input.geometries.map(reindexGeometry)}; break;
        case "LineString": output = {type: "LineString", arcs: reindexArcs(input.arcs)}; break;
        case "MultiLineString": output = {type: "MultiLineString", arcs: input.arcs.map(reindexArcs)}; break;
        case "Polygon": output = {type: "Polygon", arcs: input.arcs.map(reindexArcs)}; break;
        case "MultiPolygon": output = {type: "MultiPolygon", arcs: input.arcs.map(reindexMultiArcs)}; break;
        default: return input;
      }
      if (input.id != null) output.id = input.id;
      if (input.bbox != null) output.bbox = input.bbox;
      if (input.properties != null) output.properties = input.properties;
      return output;
    }

    function reindexArc(oldIndex) {
      return oldIndex < 0 ? ~newIndexByOldIndex[~oldIndex] : newIndexByOldIndex[oldIndex];
    }

    function reindexArcs(arcs) {
      return arcs.map(reindexArc);
    }

    function reindexMultiArcs(arcs) {
      return arcs.map(reindexArcs);
    }

    for (key in oldObjects) {
      scanGeometry(oldObjects[key]);
    }

    newArcs = new Array(newArcsLength);

    while (++oldIndex < oldArcsLength) {
      if (newIndexByOldIndex[oldIndex]) {
        newIndexByOldIndex[oldIndex] = ++newIndex;
        newArcs[newIndex] = oldArcs[oldIndex];
      }
    }

    for (key in oldObjects) {
      newObjects[key] = reindexGeometry(oldObjects[key]);
    }

    return {
      type: "Topology",
      bbox: topology.bbox,
      transform: topology.transform,
      objects: newObjects,
      arcs: newArcs
    };
  };

  var filter = function(topology, filter) {
    var oldObjects = topology.objects,
        newObjects = {},
        key;

    if (filter == null) filter = filterTrue;

    function filterGeometry(input) {
      var output, arcs;
      switch (input.type) {
        case "Polygon": {
          arcs = filterRings(input.arcs);
          output = arcs ? {type: "Polygon", arcs: arcs} : {type: null};
          break;
        }
        case "MultiPolygon": {
          arcs = input.arcs.map(filterRings).filter(filterIdentity);
          output = arcs.length ? {type: "MultiPolygon", arcs: arcs} : {type: null};
          break;
        }
        case "GeometryCollection": {
          arcs = input.geometries.map(filterGeometry).filter(filterNotNull);
          output = arcs.length ? {type: "GeometryCollection", geometries: arcs} : {type: null};
          break;
        }
        default: return input;
      }
      if (input.id != null) output.id = input.id;
      if (input.bbox != null) output.bbox = input.bbox;
      if (input.properties != null) output.properties = input.properties;
      return output;
    }

    function filterRings(arcs) {
      return arcs.length && filterExteriorRing(arcs[0]) // if the exterior is small, ignore any holes
          ? [arcs[0]].concat(arcs.slice(1).filter(filterInteriorRing))
          : null;
    }

    function filterExteriorRing(ring) {
      return filter(ring, false);
    }

    function filterInteriorRing(ring) {
      return filter(ring, true);
    }

    for (key in oldObjects) {
      newObjects[key] = filterGeometry(oldObjects[key]);
    }

    return prune({
      type: "Topology",
      bbox: topology.bbox,
      transform: topology.transform,
      objects: newObjects,
      arcs: topology.arcs
    });
  };

  function filterTrue() {
    return true;
  }

  function filterIdentity(x) {
    return x;
  }

  function filterNotNull(geometry) {
    return geometry.type != null;
  }

  var filterAttached = function(topology) {
    var ownerByArc = new Array(topology.arcs.length), // arc index -> index of unique associated ring, or -1 if used by multiple rings
        ownerIndex = 0,
        key;

    function testGeometry(o) {
      switch (o.type) {
        case "GeometryCollection": o.geometries.forEach(testGeometry); break;
        case "Polygon": testArcs(o.arcs); break;
        case "MultiPolygon": o.arcs.forEach(testArcs); break;
      }
    }

    function testArcs(arcs) {
      for (var i = 0, n = arcs.length; i < n; ++i, ++ownerIndex) {
        for (var ring = arcs[i], j = 0, m = ring.length; j < m; ++j) {
          var arc = ring[j];
          if (arc < 0) arc = ~arc;
          var owner = ownerByArc[arc];
          if (owner == null) ownerByArc[arc] = ownerIndex;
          else if (owner !== ownerIndex) ownerByArc[arc] = -1;
        }
      }
    }

    for (key in topology.objects) {
      testGeometry(topology.objects[key]);
    }

    return function(ring) {
      for (var j = 0, m = ring.length, arc; j < m; ++j) {
        if (ownerByArc[(arc = ring[j]) < 0 ? ~arc : arc] === -1) {
          return true;
        }
      }
      return false;
    };
  };

  function planarTriangleArea(triangle) {
    var a = triangle[0], b = triangle[1], c = triangle[2];
    return Math.abs((a[0] - c[0]) * (b[1] - a[1]) - (a[0] - b[0]) * (c[1] - a[1])) / 2;
  }

  function planarRingArea$1(ring) {
    var i = -1, n = ring.length, a, b = ring[n - 1], area = 0;
    while (++i < n) a = b, b = ring[i], area += a[0] * b[1] - a[1] * b[0];
    return Math.abs(area) / 2;
  }

  var filterWeight = function(topology, minWeight, weight) {
    minWeight = minWeight == null ? Number.MIN_VALUE : +minWeight;

    if (weight == null) weight = planarRingArea$1;

    return function(ring, interior) {
      return weight(feature(topology, {type: "Polygon", arcs: [ring]}).geometry.coordinates[0], interior) >= minWeight;
    };
  };

  var filterAttachedWeight = function(topology, minWeight, weight) {
    var a = filterAttached(topology),
        w = filterWeight(topology, minWeight, weight);
    return function(ring, interior) {
      return a(ring, interior) || w(ring, interior);
    };
  };

  function compare(a, b) {
    return a[1][2] - b[1][2];
  }

  var newHeap = function() {
    var heap = {},
        array = [],
        size = 0;

    heap.push = function(object) {
      up(array[object._ = size] = object, size++);
      return size;
    };

    heap.pop = function() {
      if (size <= 0) return;
      var removed = array[0], object;
      if (--size > 0) object = array[size], down(array[object._ = 0] = object, 0);
      return removed;
    };

    heap.remove = function(removed) {
      var i = removed._, object;
      if (array[i] !== removed) return; // invalid request
      if (i !== --size) object = array[size], (compare(object, removed) < 0 ? up : down)(array[object._ = i] = object, i);
      return i;
    };

    function up(object, i) {
      while (i > 0) {
        var j = ((i + 1) >> 1) - 1,
            parent = array[j];
        if (compare(object, parent) >= 0) break;
        array[parent._ = i] = parent;
        array[object._ = i = j] = object;
      }
    }

    function down(object, i) {
      while (true) {
        var r = (i + 1) << 1,
            l = r - 1,
            j = i,
            child = array[j];
        if (l < size && compare(array[l], child) < 0) child = array[j = l];
        if (r < size && compare(array[r], child) < 0) child = array[j = r];
        if (j === i) break;
        array[child._ = i] = child;
        array[object._ = i = j] = object;
      }
    }

    return heap;
  };

  function copy(point) {
    return [point[0], point[1], 0];
  }

  var presimplify = function(topology, weight) {
    var point = topology.transform ? transform(topology.transform) : copy,
        heap = newHeap();

    if (weight == null) weight = planarTriangleArea;

    var arcs = topology.arcs.map(function(arc) {
      var triangles = [],
          maxWeight = 0,
          triangle,
          i,
          n;

      arc = arc.map(point);

      for (i = 1, n = arc.length - 1; i < n; ++i) {
        triangle = [arc[i - 1], arc[i], arc[i + 1]];
        triangle[1][2] = weight(triangle);
        triangles.push(triangle);
        heap.push(triangle);
      }

      // Always keep the arc endpoints!
      arc[0][2] = arc[n][2] = Infinity;

      for (i = 0, n = triangles.length; i < n; ++i) {
        triangle = triangles[i];
        triangle.previous = triangles[i - 1];
        triangle.next = triangles[i + 1];
      }

      while (triangle = heap.pop()) {
        var previous = triangle.previous,
            next = triangle.next;

        // If the weight of the current point is less than that of the previous
        // point to be eliminated, use the latter’s weight instead. This ensures
        // that the current point cannot be eliminated without eliminating
        // previously- eliminated points.
        if (triangle[1][2] < maxWeight) triangle[1][2] = maxWeight;
        else maxWeight = triangle[1][2];

        if (previous) {
          previous.next = next;
          previous[2] = triangle[2];
          update(previous);
        }

        if (next) {
          next.previous = previous;
          next[0] = triangle[0];
          update(next);
        }
      }

      return arc;
    });

    function update(triangle) {
      heap.remove(triangle);
      triangle[1][2] = weight(triangle);
      heap.push(triangle);
    }

    return {
      type: "Topology",
      bbox: topology.bbox,
      objects: topology.objects,
      arcs: arcs
    };
  };

  var quantile = function(topology, p) {
    var array = [];

    topology.arcs.forEach(function(arc) {
      arc.forEach(function(point) {
        if (isFinite(point[2])) { // Ignore endpoints, whose weight is Infinity.
          array.push(point[2]);
        }
      });
    });

    return array.length && quantile$1(array.sort(descending), p);
  };

  function quantile$1(array, p) {
    if (!(n = array.length)) return;
    if ((p = +p) <= 0 || n < 2) return array[0];
    if (p >= 1) return array[n - 1];
    var n,
        h = (n - 1) * p,
        i = Math.floor(h),
        a = array[i],
        b = array[i + 1];
    return a + (b - a) * (h - i);
  }

  function descending(a, b) {
    return b - a;
  }

  var simplify = function(topology, minWeight) {
    minWeight = minWeight == null ? Number.MIN_VALUE : +minWeight;

    // Remove points whose weight is less than the minimum weight.
    var arcs = topology.arcs.map(function(input) {
      var i = -1,
          j = 0,
          n = input.length,
          output = new Array(n), // pessimistic
          point;

      while (++i < n) {
        if ((point = input[i])[2] >= minWeight) {
          output[j++] = [point[0], point[1]];
        }
      }

      output.length = j;
      return output;
    });

    return {
      type: "Topology",
      transform: topology.transform,
      bbox: topology.bbox,
      objects: topology.objects,
      arcs: arcs
    };
  };

  var pi = Math.PI;
  var tau = 2 * pi;
  var quarterPi = pi / 4;
  var radians = pi / 180;
  var abs = Math.abs;
  var atan2 = Math.atan2;
  var cos = Math.cos;
  var sin = Math.sin;

  function halfArea(ring, closed) {
    var i = 0,
        n = ring.length,
        sum = 0,
        point = ring[closed ? i++ : n - 1],
        lambda0, lambda1 = point[0] * radians,
        phi1 = (point[1] * radians) / 2 + quarterPi,
        cosPhi0, cosPhi1 = cos(phi1),
        sinPhi0, sinPhi1 = sin(phi1);

    for (; i < n; ++i) {
      point = ring[i];
      lambda0 = lambda1, lambda1 = point[0] * radians;
      phi1 = (point[1] * radians) / 2 + quarterPi;
      cosPhi0 = cosPhi1, cosPhi1 = cos(phi1);
      sinPhi0 = sinPhi1, sinPhi1 = sin(phi1);

      // Spherical excess E for a spherical triangle with vertices: south pole,
      // previous point, current point.  Uses a formula derived from Cagnoli’s
      // theorem.  See Todhunter, Spherical Trig. (1871), Sec. 103, Eq. (2).
      // See https://github.com/d3/d3-geo/blob/master/README.md#geoArea
      var dLambda = lambda1 - lambda0,
          sdLambda = dLambda >= 0 ? 1 : -1,
          adLambda = sdLambda * dLambda,
          k = sinPhi0 * sinPhi1,
          u = cosPhi0 * cosPhi1 + k * cos(adLambda),
          v = k * sdLambda * sin(adLambda);
      sum += atan2(v, u);
    }

    return sum;
  }

  function sphericalRingArea(ring, interior) {
    var sum = halfArea(ring, true);
    if (interior) sum *= -1;
    return (sum < 0 ? tau + sum : sum) * 2;
  }

  function sphericalTriangleArea(t) {
    return abs(halfArea(t, false)) * 2;
  }

  exports.bbox = bbox;
  exports.feature = feature;
  exports.mesh = mesh;
  exports.meshArcs = meshArcs;
  exports.merge = merge;
  exports.mergeArcs = mergeArcs;
  exports.neighbors = neighbors;
  exports.quantize = quantize;
  exports.transform = transform;
  exports.untransform = untransform;
  exports.topology = topology;
  exports.filter = filter;
  exports.filterAttached = filterAttached;
  exports.filterAttachedWeight = filterAttachedWeight;
  exports.filterWeight = filterWeight;
  exports.planarRingArea = planarRingArea$1;
  exports.planarTriangleArea = planarTriangleArea;
  exports.presimplify = presimplify;
  exports.quantile = quantile;
  exports.simplify = simplify;
  exports.sphericalRingArea = sphericalRingArea;
  exports.sphericalTriangleArea = sphericalTriangleArea;

  Object.defineProperty(exports, '__esModule', { value: true });

  })));

  var topojson = tmp$3.topojson;

  function defaultCrsFunction(coordinates) {
    return Cartesian3.fromDegrees(coordinates[0], coordinates[1], coordinates[2]);
  }

  var crsNames = {
    "urn:ogc:def:crs:OGC:1.3:CRS84": defaultCrsFunction,
    "EPSG:4326": defaultCrsFunction,
    "urn:ogc:def:crs:EPSG::4326": defaultCrsFunction,
  };

  var crsLinkHrefs = {};
  var crsLinkTypes = {};
  var defaultMarkerSize = 48;
  var defaultMarkerSymbol;
  var defaultMarkerColor = Color.ROYALBLUE;
  var defaultStroke = Color.YELLOW;
  var defaultStrokeWidth = 2;
  var defaultFill$1 = Color.fromBytes(255, 255, 0, 100);
  var defaultClampToGround = false;

  var sizes = {
    small: 24,
    medium: 48,
    large: 64,
  };

  var simpleStyleIdentifiers = [
    "title",
    "description", //
    "marker-size",
    "marker-symbol",
    "marker-color",
    "stroke", //
    "stroke-opacity",
    "stroke-width",
    "fill",
    "fill-opacity",
  ];

  function defaultDescribe(properties, nameProperty) {
    var html = "";
    for (var key in properties) {
      if (properties.hasOwnProperty(key)) {
        if (key === nameProperty || simpleStyleIdentifiers.indexOf(key) !== -1) {
          continue;
        }
        var value = properties[key];
        if (defined(value)) {
          if (typeof value === "object") {
            html +=
              "<tr><th>" +
              key +
              "</th><td>" +
              defaultDescribe(value) +
              "</td></tr>";
          } else {
            html += "<tr><th>" + key + "</th><td>" + value + "</td></tr>";
          }
        }
      }
    }

    if (html.length > 0) {
      html =
        '<table class="cesium-infoBox-defaultTable"><tbody>' +
        html +
        "</tbody></table>";
    }

    return html;
  }

  function createDescriptionCallback(describe, properties, nameProperty) {
    var description;
    return function (time, result) {
      if (!defined(description)) {
        description = describe(properties, nameProperty);
      }
      return description;
    };
  }

  function defaultDescribeProperty(properties, nameProperty) {
    return new CallbackProperty(
      createDescriptionCallback(defaultDescribe, properties, nameProperty),
      true
    );
  }

  //GeoJSON specifies only the Feature object has a usable id property
  //But since "multi" geometries create multiple entity,
  //we can't use it for them either.
  function createObject(geoJson, entityCollection, describe) {
    var id = geoJson.id;
    if (!defined(id) || geoJson.type !== "Feature") {
      id = createGuid();
    } else {
      var i = 2;
      var finalId = id;
      while (defined(entityCollection.getById(finalId))) {
        finalId = id + "_" + i;
        i++;
      }
      id = finalId;
    }

    var entity = entityCollection.getOrCreateEntity(id);
    var properties = geoJson.properties;
    if (defined(properties)) {
      entity.properties = properties;

      var nameProperty;

      //Check for the simplestyle specified name first.
      var name = properties.title;
      if (defined(name)) {
        entity.name = name;
        nameProperty = "title";
      } else {
        //Else, find the name by selecting an appropriate property.
        //The name will be obtained based on this order:
        //1) The first case-insensitive property with the name 'title',
        //2) The first case-insensitive property with the name 'name',
        //3) The first property containing the word 'title'.
        //4) The first property containing the word 'name',
        var namePropertyPrecedence = Number.MAX_VALUE;
        for (var key in properties) {
          if (properties.hasOwnProperty(key) && properties[key]) {
            var lowerKey = key.toLowerCase();

            if (namePropertyPrecedence > 1 && lowerKey === "title") {
              namePropertyPrecedence = 1;
              nameProperty = key;
              break;
            } else if (namePropertyPrecedence > 2 && lowerKey === "name") {
              namePropertyPrecedence = 2;
              nameProperty = key;
            } else if (namePropertyPrecedence > 3 && /title/i.test(key)) {
              namePropertyPrecedence = 3;
              nameProperty = key;
            } else if (namePropertyPrecedence > 4 && /name/i.test(key)) {
              namePropertyPrecedence = 4;
              nameProperty = key;
            }
          }
        }
        if (defined(nameProperty)) {
          entity.name = properties[nameProperty];
        }
      }

      var description = properties.description;
      if (description !== null) {
        entity.description = !defined(description)
          ? describe(properties, nameProperty)
          : new ConstantProperty(description);
      }
    }
    return entity;
  }

  function coordinatesArrayToCartesianArray(coordinates, crsFunction) {
    var positions = new Array(coordinates.length);
    for (var i = 0; i < coordinates.length; i++) {
      positions[i] = crsFunction(coordinates[i]);
    }
    return positions;
  }

  var geoJsonObjectTypes = {
    Feature: processFeature,
    FeatureCollection: processFeatureCollection,
    GeometryCollection: processGeometryCollection,
    LineString: processLineString,
    MultiLineString: processMultiLineString,
    MultiPoint: processMultiPoint,
    MultiPolygon: processMultiPolygon,
    Point: processPoint$1,
    Polygon: processPolygon$1,
    Topology: processTopology,
  };

  var geometryTypes = {
    GeometryCollection: processGeometryCollection,
    LineString: processLineString,
    MultiLineString: processMultiLineString,
    MultiPoint: processMultiPoint,
    MultiPolygon: processMultiPolygon,
    Point: processPoint$1,
    Polygon: processPolygon$1,
    Topology: processTopology,
  };

  // GeoJSON processing functions
  function processFeature(dataSource, feature, notUsed, crsFunction, options) {
    if (feature.geometry === null) {
      //Null geometry is allowed, so just create an empty entity instance for it.
      createObject(feature, dataSource._entityCollection, options.describe);
      return;
    }

    if (!defined(feature.geometry)) {
      throw new RuntimeError("feature.geometry is required.");
    }

    var geometryType = feature.geometry.type;
    var geometryHandler = geometryTypes[geometryType];
    if (!defined(geometryHandler)) {
      throw new RuntimeError("Unknown geometry type: " + geometryType);
    }
    geometryHandler(dataSource, feature, feature.geometry, crsFunction, options);
  }

  function processFeatureCollection(
    dataSource,
    featureCollection,
    notUsed,
    crsFunction,
    options
  ) {
    var features = featureCollection.features;
    for (var i = 0, len = features.length; i < len; i++) {
      processFeature(dataSource, features[i], undefined, crsFunction, options);
    }
  }

  function processGeometryCollection(
    dataSource,
    geoJson,
    geometryCollection,
    crsFunction,
    options
  ) {
    var geometries = geometryCollection.geometries;
    for (var i = 0, len = geometries.length; i < len; i++) {
      var geometry = geometries[i];
      var geometryType = geometry.type;
      var geometryHandler = geometryTypes[geometryType];
      if (!defined(geometryHandler)) {
        throw new RuntimeError("Unknown geometry type: " + geometryType);
      }
      geometryHandler(dataSource, geoJson, geometry, crsFunction, options);
    }
  }

  function createPoint(dataSource, geoJson, crsFunction, coordinates, options) {
    var symbol = options.markerSymbol;
    var color = options.markerColor;
    var size = options.markerSize;

    var properties = geoJson.properties;
    if (defined(properties)) {
      var cssColor = properties["marker-color"];
      if (defined(cssColor)) {
        color = Color.fromCssColorString(cssColor);
      }

      size = defaultValue(sizes[properties["marker-size"]], size);
      var markerSymbol = properties["marker-symbol"];
      if (defined(markerSymbol)) {
        symbol = markerSymbol;
      }
    }

    var canvasOrPromise;
    if (defined(symbol)) {
      if (symbol.length === 1) {
        canvasOrPromise = dataSource._pinBuilder.fromText(
          symbol.toUpperCase(),
          color,
          size
        );
      } else {
        canvasOrPromise = dataSource._pinBuilder.fromMakiIconId(
          symbol,
          color,
          size
        );
      }
    } else {
      canvasOrPromise = dataSource._pinBuilder.fromColor(color, size);
    }

    var billboard = new BillboardGraphics();
    billboard.verticalOrigin = new ConstantProperty(VerticalOrigin$1.BOTTOM);

    // Clamp to ground if there isn't a height specified
    if (coordinates.length === 2 && options.clampToGround) {
      billboard.heightReference = HeightReference$1.CLAMP_TO_GROUND;
    }

    var entity = createObject(
      geoJson,
      dataSource._entityCollection,
      options.describe
    );
    entity.billboard = billboard;
    entity.position = new ConstantPositionProperty(crsFunction(coordinates));

    var promise = when(canvasOrPromise)
      .then(function (image) {
        billboard.image = new ConstantProperty(image);
      })
      .otherwise(function () {
        billboard.image = new ConstantProperty(
          dataSource._pinBuilder.fromColor(color, size)
        );
      });

    dataSource._promises.push(promise);
  }

  function processPoint$1(dataSource, geoJson, geometry, crsFunction, options) {
    createPoint(dataSource, geoJson, crsFunction, geometry.coordinates, options);
  }

  function processMultiPoint(
    dataSource,
    geoJson,
    geometry,
    crsFunction,
    options
  ) {
    var coordinates = geometry.coordinates;
    for (var i = 0; i < coordinates.length; i++) {
      createPoint(dataSource, geoJson, crsFunction, coordinates[i], options);
    }
  }

  function createLineString(
    dataSource,
    geoJson,
    crsFunction,
    coordinates,
    options
  ) {
    var material = options.strokeMaterialProperty;
    var widthProperty = options.strokeWidthProperty;

    var properties = geoJson.properties;
    if (defined(properties)) {
      var width = properties["stroke-width"];
      if (defined(width)) {
        widthProperty = new ConstantProperty(width);
      }

      var color;
      var stroke = properties.stroke;
      if (defined(stroke)) {
        color = Color.fromCssColorString(stroke);
      }
      var opacity = properties["stroke-opacity"];
      if (defined(opacity) && opacity !== 1.0) {
        if (!defined(color)) {
          color = material.color.clone();
        }
        color.alpha = opacity;
      }
      if (defined(color)) {
        material = new ColorMaterialProperty(color);
      }
    }

    var entity = createObject(
      geoJson,
      dataSource._entityCollection,
      options.describe
    );
    var polylineGraphics = new PolylineGraphics();
    entity.polyline = polylineGraphics;

    polylineGraphics.clampToGround = options.clampToGround;
    polylineGraphics.material = material;
    polylineGraphics.width = widthProperty;
    polylineGraphics.positions = new ConstantProperty(
      coordinatesArrayToCartesianArray(coordinates, crsFunction)
    );
    polylineGraphics.arcType = ArcType$1.RHUMB;
  }

  function processLineString(
    dataSource,
    geoJson,
    geometry,
    crsFunction,
    options
  ) {
    createLineString(
      dataSource,
      geoJson,
      crsFunction,
      geometry.coordinates,
      options
    );
  }

  function processMultiLineString(
    dataSource,
    geoJson,
    geometry,
    crsFunction,
    options
  ) {
    var lineStrings = geometry.coordinates;
    for (var i = 0; i < lineStrings.length; i++) {
      createLineString(dataSource, geoJson, crsFunction, lineStrings[i], options);
    }
  }

  function createPolygon(dataSource, geoJson, crsFunction, coordinates, options) {
    if (coordinates.length === 0 || coordinates[0].length === 0) {
      return;
    }

    var outlineColorProperty = options.strokeMaterialProperty.color;
    var material = options.fillMaterialProperty;
    var widthProperty = options.strokeWidthProperty;

    var properties = geoJson.properties;
    if (defined(properties)) {
      var width = properties["stroke-width"];
      if (defined(width)) {
        widthProperty = new ConstantProperty(width);
      }

      var color;
      var stroke = properties.stroke;
      if (defined(stroke)) {
        color = Color.fromCssColorString(stroke);
      }
      var opacity = properties["stroke-opacity"];
      if (defined(opacity) && opacity !== 1.0) {
        if (!defined(color)) {
          color = options.strokeMaterialProperty.color.clone();
        }
        color.alpha = opacity;
      }

      if (defined(color)) {
        outlineColorProperty = new ConstantProperty(color);
      }

      var fillColor;
      var fill = properties.fill;
      if (defined(fill)) {
        fillColor = Color.fromCssColorString(fill);
        fillColor.alpha = material.color.alpha;
      }
      opacity = properties["fill-opacity"];
      if (defined(opacity) && opacity !== material.color.alpha) {
        if (!defined(fillColor)) {
          fillColor = material.color.clone();
        }
        fillColor.alpha = opacity;
      }
      if (defined(fillColor)) {
        material = new ColorMaterialProperty(fillColor);
      }
    }

    var polygon = new PolygonGraphics();
    polygon.outline = new ConstantProperty(true);
    polygon.outlineColor = outlineColorProperty;
    polygon.outlineWidth = widthProperty;
    polygon.material = material;
    polygon.arcType = ArcType$1.RHUMB;

    var holes = [];
    for (var i = 1, len = coordinates.length; i < len; i++) {
      holes.push(
        new PolygonHierarchy(
          coordinatesArrayToCartesianArray(coordinates[i], crsFunction)
        )
      );
    }

    var positions = coordinates[0];
    polygon.hierarchy = new ConstantProperty(
      new PolygonHierarchy(
        coordinatesArrayToCartesianArray(positions, crsFunction),
        holes
      )
    );
    if (positions[0].length > 2) {
      polygon.perPositionHeight = new ConstantProperty(true);
    } else if (!options.clampToGround) {
      polygon.height = 0;
    }

    var entity = createObject(
      geoJson,
      dataSource._entityCollection,
      options.describe
    );
    entity.polygon = polygon;
  }

  function processPolygon$1(dataSource, geoJson, geometry, crsFunction, options) {
    createPolygon(
      dataSource,
      geoJson,
      crsFunction,
      geometry.coordinates,
      options
    );
  }

  function processMultiPolygon(
    dataSource,
    geoJson,
    geometry,
    crsFunction,
    options
  ) {
    var polygons = geometry.coordinates;
    for (var i = 0; i < polygons.length; i++) {
      createPolygon(dataSource, geoJson, crsFunction, polygons[i], options);
    }
  }

  function processTopology(dataSource, geoJson, geometry, crsFunction, options) {
    for (var property in geometry.objects) {
      if (geometry.objects.hasOwnProperty(property)) {
        var feature = topojson.feature(geometry, geometry.objects[property]);
        var typeHandler = geoJsonObjectTypes[feature.type];
        typeHandler(dataSource, feature, feature, crsFunction, options);
      }
    }
  }

  /**
   * @typedef {Object} GeoJsonDataSource.LoadOptions
   *
   * Initialization options for the `load` method.
   *
   * @property {String} [sourceUri] Overrides the url to use for resolving relative links.
   * @property {Number} [markerSize=GeoJsonDataSource.markerSize] The default size of the map pin created for each point, in pixels.
   * @property {String} [markerSymbol=GeoJsonDataSource.markerSymbol] The default symbol of the map pin created for each point.
   * @property {Color} [markerColor=GeoJsonDataSource.markerColor] The default color of the map pin created for each point.
   * @property {Color} [stroke=GeoJsonDataSource.stroke] The default color of polylines and polygon outlines.
   * @property {Number} [strokeWidth=GeoJsonDataSource.strokeWidth] The default width of polylines and polygon outlines.
   * @property {Color} [fill=GeoJsonDataSource.fill] The default color for polygon interiors.
   * @property {Boolean} [clampToGround=GeoJsonDataSource.clampToGround] true if we want the geometry features (polygons or linestrings) clamped to the ground.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * A {@link DataSource} which processes both
   * {@link http://www.geojson.org/|GeoJSON} and {@link https://github.com/mbostock/topojson|TopoJSON} data.
   * {@link https://github.com/mapbox/simplestyle-spec|simplestyle-spec} properties will also be used if they
   * are present.
   *
   * @alias GeoJsonDataSource
   * @constructor
   *
   * @param {String} [name] The name of this data source.  If undefined, a name will be taken from
   *                        the name of the GeoJSON file.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=GeoJSON%20and%20TopoJSON.html|Cesium Sandcastle GeoJSON and TopoJSON Demo}
   * @demo {@link https://sandcastle.cesium.com/index.html?src=GeoJSON%20simplestyle.html|Cesium Sandcastle GeoJSON simplestyle Demo}
   *
   * @example
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.dataSources.add(Cesium.GeoJsonDataSource.load('../../SampleData/ne_10m_us_states.topojson', {
   *   stroke: Cesium.Color.HOTPINK,
   *   fill: Cesium.Color.PINK,
   *   strokeWidth: 3,
   *   markerSymbol: '?'
   * }));
   */
  function GeoJsonDataSource(name) {
    this._name = name;
    this._changed = new Event();
    this._error = new Event();
    this._isLoading = false;
    this._loading = new Event();
    this._entityCollection = new EntityCollection(this);
    this._promises = [];
    this._pinBuilder = new PinBuilder();
    this._entityCluster = new EntityCluster();
    this._credit = undefined;
    this._resourceCredits = [];
  }

  /**
   * Creates a Promise to a new instance loaded with the provided GeoJSON or TopoJSON data.
   *
   * @param {Resource|String|Object} data A url, GeoJSON object, or TopoJSON object to be loaded.
   * @param {GeoJsonDataSource.LoadOptions} [options] An object specifying configuration options
   *
   * @returns {Promise.<GeoJsonDataSource>} A promise that will resolve when the data is loaded.
   */
  GeoJsonDataSource.load = function (data, options) {
    return new GeoJsonDataSource().load(data, options);
  };

  Object.defineProperties(GeoJsonDataSource, {
    /**
     * Gets or sets the default size of the map pin created for each point, in pixels.
     * @memberof GeoJsonDataSource
     * @type {Number}
     * @default 48
     */
    markerSize: {
      get: function () {
        return defaultMarkerSize;
      },
      set: function (value) {
        defaultMarkerSize = value;
      },
    },
    /**
     * Gets or sets the default symbol of the map pin created for each point.
     * This can be any valid {@link http://mapbox.com/maki/|Maki} identifier, any single character,
     * or blank if no symbol is to be used.
     * @memberof GeoJsonDataSource
     * @type {String}
     */
    markerSymbol: {
      get: function () {
        return defaultMarkerSymbol;
      },
      set: function (value) {
        defaultMarkerSymbol = value;
      },
    },
    /**
     * Gets or sets the default color of the map pin created for each point.
     * @memberof GeoJsonDataSource
     * @type {Color}
     * @default Color.ROYALBLUE
     */
    markerColor: {
      get: function () {
        return defaultMarkerColor;
      },
      set: function (value) {
        defaultMarkerColor = value;
      },
    },
    /**
     * Gets or sets the default color of polylines and polygon outlines.
     * @memberof GeoJsonDataSource
     * @type {Color}
     * @default Color.BLACK
     */
    stroke: {
      get: function () {
        return defaultStroke;
      },
      set: function (value) {
        defaultStroke = value;
      },
    },
    /**
     * Gets or sets the default width of polylines and polygon outlines.
     * @memberof GeoJsonDataSource
     * @type {Number}
     * @default 2.0
     */
    strokeWidth: {
      get: function () {
        return defaultStrokeWidth;
      },
      set: function (value) {
        defaultStrokeWidth = value;
      },
    },
    /**
     * Gets or sets default color for polygon interiors.
     * @memberof GeoJsonDataSource
     * @type {Color}
     * @default Color.YELLOW
     */
    fill: {
      get: function () {
        return defaultFill$1;
      },
      set: function (value) {
        defaultFill$1 = value;
      },
    },
    /**
     * Gets or sets default of whether to clamp to the ground.
     * @memberof GeoJsonDataSource
     * @type {Boolean}
     * @default false
     */
    clampToGround: {
      get: function () {
        return defaultClampToGround;
      },
      set: function (value) {
        defaultClampToGround = value;
      },
    },

    /**
     * Gets an object that maps the name of a crs to a callback function which takes a GeoJSON coordinate
     * and transforms it into a WGS84 Earth-fixed Cartesian.  Older versions of GeoJSON which
     * supported the EPSG type can be added to this list as well, by specifying the complete EPSG name,
     * for example 'EPSG:4326'.
     * @memberof GeoJsonDataSource
     * @type {Object}
     */
    crsNames: {
      get: function () {
        return crsNames;
      },
    },

    /**
     * Gets an object that maps the href property of a crs link to a callback function
     * which takes the crs properties object and returns a Promise that resolves
     * to a function that takes a GeoJSON coordinate and transforms it into a WGS84 Earth-fixed Cartesian.
     * Items in this object take precedence over those defined in <code>crsLinkHrefs</code>, assuming
     * the link has a type specified.
     * @memberof GeoJsonDataSource
     * @type {Object}
     */
    crsLinkHrefs: {
      get: function () {
        return crsLinkHrefs;
      },
    },

    /**
     * Gets an object that maps the type property of a crs link to a callback function
     * which takes the crs properties object and returns a Promise that resolves
     * to a function that takes a GeoJSON coordinate and transforms it into a WGS84 Earth-fixed Cartesian.
     * Items in <code>crsLinkHrefs</code> take precedence over this object.
     * @memberof GeoJsonDataSource
     * @type {Object}
     */
    crsLinkTypes: {
      get: function () {
        return crsLinkTypes;
      },
    },
  });

  Object.defineProperties(GeoJsonDataSource.prototype, {
    /**
     * Gets or sets a human-readable name for this instance.
     * @memberof GeoJsonDataSource.prototype
     * @type {String}
     */
    name: {
      get: function () {
        return this._name;
      },
      set: function (value) {
        if (this._name !== value) {
          this._name = value;
          this._changed.raiseEvent(this);
        }
      },
    },
    /**
     * This DataSource only defines static data, therefore this property is always undefined.
     * @memberof GeoJsonDataSource.prototype
     * @type {DataSourceClock}
     */
    clock: {
      value: undefined,
      writable: false,
    },
    /**
     * Gets the collection of {@link Entity} instances.
     * @memberof GeoJsonDataSource.prototype
     * @type {EntityCollection}
     */
    entities: {
      get: function () {
        return this._entityCollection;
      },
    },
    /**
     * Gets a value indicating if the data source is currently loading data.
     * @memberof GeoJsonDataSource.prototype
     * @type {Boolean}
     */
    isLoading: {
      get: function () {
        return this._isLoading;
      },
    },
    /**
     * Gets an event that will be raised when the underlying data changes.
     * @memberof GeoJsonDataSource.prototype
     * @type {Event}
     */
    changedEvent: {
      get: function () {
        return this._changed;
      },
    },
    /**
     * Gets an event that will be raised if an error is encountered during processing.
     * @memberof GeoJsonDataSource.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._error;
      },
    },
    /**
     * Gets an event that will be raised when the data source either starts or stops loading.
     * @memberof GeoJsonDataSource.prototype
     * @type {Event}
     */
    loadingEvent: {
      get: function () {
        return this._loading;
      },
    },
    /**
     * Gets whether or not this data source should be displayed.
     * @memberof GeoJsonDataSource.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._entityCollection.show;
      },
      set: function (value) {
        this._entityCollection.show = value;
      },
    },

    /**
     * Gets or sets the clustering options for this data source. This object can be shared between multiple data sources.
     *
     * @memberof GeoJsonDataSource.prototype
     * @type {EntityCluster}
     */
    clustering: {
      get: function () {
        return this._entityCluster;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value must be defined.");
        }
        //>>includeEnd('debug');
        this._entityCluster = value;
      },
    },
    /**
     * Gets the credit that will be displayed for the data source
     * @memberof GeoJsonDataSource.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },
  });

  /**
   * Asynchronously loads the provided GeoJSON or TopoJSON data, replacing any existing data.
   *
   * @param {Resource|String|Object} data A url, GeoJSON object, or TopoJSON object to be loaded.
   * @param {Object} [options] An object with the following properties:
   * @param {String} [options.sourceUri] Overrides the url to use for resolving relative links.
   * @param {GeoJsonDataSource.describe} [options.describe=GeoJsonDataSource.defaultDescribeProperty] A function which returns a Property object (or just a string),
   *                                                                                which converts the properties into an html description.
   * @param {Number} [options.markerSize=GeoJsonDataSource.markerSize] The default size of the map pin created for each point, in pixels.
   * @param {String} [options.markerSymbol=GeoJsonDataSource.markerSymbol] The default symbol of the map pin created for each point.
   * @param {Color} [options.markerColor=GeoJsonDataSource.markerColor] The default color of the map pin created for each point.
   * @param {Color} [options.stroke=GeoJsonDataSource.stroke] The default color of polylines and polygon outlines.
   * @param {Number} [options.strokeWidth=GeoJsonDataSource.strokeWidth] The default width of polylines and polygon outlines.
   * @param {Color} [options.fill=GeoJsonDataSource.fill] The default color for polygon interiors.
   * @param {Boolean} [options.clampToGround=GeoJsonDataSource.clampToGround] true if we want the features clamped to the ground.
   * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
   *
   * @returns {Promise.<GeoJsonDataSource>} a promise that will resolve when the GeoJSON is loaded.
   */
  GeoJsonDataSource.prototype.load = function (data, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(data)) {
      throw new DeveloperError("data is required.");
    }
    //>>includeEnd('debug');

    DataSource.setLoading(this, true);
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    // User specified credit
    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    var promise = data;
    var sourceUri = options.sourceUri;
    if (typeof data === "string" || data instanceof Resource) {
      data = Resource.createIfNeeded(data);
      promise = data.fetchJson();
      sourceUri = defaultValue(sourceUri, data.getUrlComponent());

      // Add resource credits to our list of credits to display
      var resourceCredits = this._resourceCredits;
      var credits = data.credits;
      if (defined(credits)) {
        var length = credits.length;
        for (var i = 0; i < length; i++) {
          resourceCredits.push(credits[i]);
        }
      }
    }

    options = {
      describe: defaultValue(options.describe, defaultDescribeProperty),
      markerSize: defaultValue(options.markerSize, defaultMarkerSize),
      markerSymbol: defaultValue(options.markerSymbol, defaultMarkerSymbol),
      markerColor: defaultValue(options.markerColor, defaultMarkerColor),
      strokeWidthProperty: new ConstantProperty(
        defaultValue(options.strokeWidth, defaultStrokeWidth)
      ),
      strokeMaterialProperty: new ColorMaterialProperty(
        defaultValue(options.stroke, defaultStroke)
      ),
      fillMaterialProperty: new ColorMaterialProperty(
        defaultValue(options.fill, defaultFill$1)
      ),
      clampToGround: defaultValue(options.clampToGround, defaultClampToGround),
    };

    var that = this;
    return when(promise, function (geoJson) {
      return load$1(that, geoJson, options, sourceUri);
    }).otherwise(function (error) {
      DataSource.setLoading(that, false);
      that._error.raiseEvent(that, error);
      console.log(error);
      return when.reject(error);
    });
  };

  /**
   * Updates the data source to the provided time.  This function is optional and
   * is not required to be implemented.  It is provided for data sources which
   * retrieve data based on the current animation time or scene state.
   * If implemented, update will be called by {@link DataSourceDisplay} once a frame.
   *
   * @param {JulianDate} time The simulation time.
   * @returns {Boolean} True if this data source is ready to be displayed at the provided time, false otherwise.
   */
  GeoJsonDataSource.prototype.update = function (time) {
    return true;
  };

  function load$1(that, geoJson, options, sourceUri) {
    var name;
    if (defined(sourceUri)) {
      name = getFilenameFromUri(sourceUri);
    }

    if (defined(name) && that._name !== name) {
      that._name = name;
      that._changed.raiseEvent(that);
    }

    var typeHandler = geoJsonObjectTypes[geoJson.type];
    if (!defined(typeHandler)) {
      throw new RuntimeError("Unsupported GeoJSON object type: " + geoJson.type);
    }

    //Check for a Coordinate Reference System.
    var crs = geoJson.crs;
    var crsFunction = crs !== null ? defaultCrsFunction : null;

    if (defined(crs)) {
      if (!defined(crs.properties)) {
        throw new RuntimeError("crs.properties is undefined.");
      }

      var properties = crs.properties;
      if (crs.type === "name") {
        crsFunction = crsNames[properties.name];
        if (!defined(crsFunction)) {
          throw new RuntimeError("Unknown crs name: " + properties.name);
        }
      } else if (crs.type === "link") {
        var handler = crsLinkHrefs[properties.href];
        if (!defined(handler)) {
          handler = crsLinkTypes[properties.type];
        }

        if (!defined(handler)) {
          throw new RuntimeError(
            "Unable to resolve crs link: " + JSON.stringify(properties)
          );
        }

        crsFunction = handler(properties);
      } else if (crs.type === "EPSG") {
        crsFunction = crsNames["EPSG:" + properties.code];
        if (!defined(crsFunction)) {
          throw new RuntimeError("Unknown crs EPSG code: " + properties.code);
        }
      } else {
        throw new RuntimeError("Unknown crs type: " + crs.type);
      }
    }

    return when(crsFunction, function (crsFunction) {
      that._entityCollection.removeAll();

      // null is a valid value for the crs, but means the entire load process becomes a no-op
      // because we can't assume anything about the coordinates.
      if (crsFunction !== null) {
        typeHandler(that, geoJson, geoJson, crsFunction, options);
      }

      return when.all(that._promises, function () {
        that._promises.length = 0;
        DataSource.setLoading(that, false);
        return that;
      });
    });
  }

  /**
   * Representation of <Camera> from KML
   * @alias KmlCamera
   * @constructor
   *
   * @param {Cartesian3} position camera position
   * @param {HeadingPitchRoll} headingPitchRoll camera orientation
   */
  function KmlCamera(position, headingPitchRoll) {
    this.position = position;
    this.headingPitchRoll = headingPitchRoll;
  }

  var tmp$4 = {};

  /*!
   * Autolinker.js
   * 3.11.0
   *
   * Copyright(c) 2019 Gregory Jacobs <greg@greg-jacobs.com>
   * MIT License
   *
   * https://github.com/gregjacobs/Autolinker.js
   */
  (function (global, factory) {
      global.Autolinker = factory();
  }(tmp$4, function () {
      /**
       * Assigns (shallow copies) the properties of `src` onto `dest`, if the
       * corresponding property on `dest` === `undefined`.
       *
       * @param {Object} dest The destination object.
       * @param {Object} src The source object.
       * @return {Object} The destination object (`dest`)
       */
      function defaults(dest, src) {
          for (var prop in src) {
              if (src.hasOwnProperty(prop) && dest[prop] === undefined) {
                  dest[prop] = src[prop];
              }
          }
          return dest;
      }
      /**
       * Truncates the `str` at `len - ellipsisChars.length`, and adds the `ellipsisChars` to the
       * end of the string (by default, two periods: '..'). If the `str` length does not exceed
       * `len`, the string will be returned unchanged.
       *
       * @param {String} str The string to truncate and add an ellipsis to.
       * @param {Number} truncateLen The length to truncate the string at.
       * @param {String} [ellipsisChars=...] The ellipsis character(s) to add to the end of `str`
       *   when truncated. Defaults to '...'
       */
      function ellipsis(str, truncateLen, ellipsisChars) {
          var ellipsisLength;
          if (str.length > truncateLen) {
              if (ellipsisChars == null) {
                  ellipsisChars = '&hellip;';
                  ellipsisLength = 3;
              }
              else {
                  ellipsisLength = ellipsisChars.length;
              }
              str = str.substring(0, truncateLen - ellipsisLength) + ellipsisChars;
          }
          return str;
      }
      /**
       * Supports `Array.prototype.indexOf()` functionality for old IE (IE8 and below).
       *
       * @param {Array} arr The array to find an element of.
       * @param {*} element The element to find in the array, and return the index of.
       * @return {Number} The index of the `element`, or -1 if it was not found.
       */
      function indexOf(arr, element) {
          if (Array.prototype.indexOf) {
              return arr.indexOf(element);
          }
          else {
              for (var i = 0, len = arr.length; i < len; i++) {
                  if (arr[i] === element)
                      return i;
              }
              return -1;
          }
      }
      /**
       * Removes array elements based on a filtering function. Mutates the input
       * array.
       *
       * Using this instead of the ES5 Array.prototype.filter() function, to allow
       * Autolinker compatibility with IE8, and also to prevent creating many new
       * arrays in memory for filtering.
       *
       * @param {Array} arr The array to remove elements from. This array is
       *   mutated.
       * @param {Function} fn A function which should return `true` to
       *   remove an element.
       * @return {Array} The mutated input `arr`.
       */
      function remove(arr, fn) {
          for (var i = arr.length - 1; i >= 0; i--) {
              if (fn(arr[i]) === true) {
                  arr.splice(i, 1);
              }
          }
      }
      /**
       * Performs the functionality of what modern browsers do when `String.prototype.split()` is called
       * with a regular expression that contains capturing parenthesis.
       *
       * For example:
       *
       *     // Modern browsers:
       *     "a,b,c".split( /(,)/ );  // --> [ 'a', ',', 'b', ',', 'c' ]
       *
       *     // Old IE (including IE8):
       *     "a,b,c".split( /(,)/ );  // --> [ 'a', 'b', 'c' ]
       *
       * This method emulates the functionality of modern browsers for the old IE case.
       *
       * @param {String} str The string to split.
       * @param {RegExp} splitRegex The regular expression to split the input `str` on. The splitting
       *   character(s) will be spliced into the array, as in the "modern browsers" example in the
       *   description of this method.
       *   Note #1: the supplied regular expression **must** have the 'g' flag specified.
       *   Note #2: for simplicity's sake, the regular expression does not need
       *   to contain capturing parenthesis - it will be assumed that any match has them.
       * @return {String[]} The split array of strings, with the splitting character(s) included.
       */
      function splitAndCapture(str, splitRegex) {
          if (!splitRegex.global)
              throw new Error("`splitRegex` must have the 'g' flag set");
          var result = [], lastIdx = 0, match;
          while (match = splitRegex.exec(str)) {
              result.push(str.substring(lastIdx, match.index));
              result.push(match[0]); // push the splitting char(s)
              lastIdx = match.index + match[0].length;
          }
          result.push(str.substring(lastIdx));
          return result;
      }
      /**
       * Function that should never be called but is used to check that every
       * enum value is handled using TypeScript's 'never' type.
       */
      function throwUnhandledCaseError(theValue) {
          throw new Error("Unhandled case for value: '" + theValue + "'");
      }

      /**
       * @class Autolinker.HtmlTag
       * @extends Object
       *
       * Represents an HTML tag, which can be used to easily build/modify HTML tags programmatically.
       *
       * Autolinker uses this abstraction to create HTML tags, and then write them out as strings. You may also use
       * this class in your code, especially within a {@link Autolinker#replaceFn replaceFn}.
       *
       * ## Examples
       *
       * Example instantiation:
       *
       *     var tag = new Autolinker.HtmlTag( {
       *         tagName : 'a',
       *         attrs   : { 'href': 'http://google.com', 'class': 'external-link' },
       *         innerHtml : 'Google'
       *     } );
       *
       *     tag.toAnchorString();  // <a href="http://google.com" class="external-link">Google</a>
       *
       *     // Individual accessor methods
       *     tag.getTagName();                 // 'a'
       *     tag.getAttr( 'href' );            // 'http://google.com'
       *     tag.hasClass( 'external-link' );  // true
       *
       *
       * Using mutator methods (which may be used in combination with instantiation config properties):
       *
       *     var tag = new Autolinker.HtmlTag();
       *     tag.setTagName( 'a' );
       *     tag.setAttr( 'href', 'http://google.com' );
       *     tag.addClass( 'external-link' );
       *     tag.setInnerHtml( 'Google' );
       *
       *     tag.getTagName();                 // 'a'
       *     tag.getAttr( 'href' );            // 'http://google.com'
       *     tag.hasClass( 'external-link' );  // true
       *
       *     tag.toAnchorString();  // <a href="http://google.com" class="external-link">Google</a>
       *
       *
       * ## Example use within a {@link Autolinker#replaceFn replaceFn}
       *
       *     var html = Autolinker.link( "Test google.com", {
       *         replaceFn : function( match ) {
       *             var tag = match.buildTag();  // returns an {@link Autolinker.HtmlTag} instance, configured with the Match's href and anchor text
       *             tag.setAttr( 'rel', 'nofollow' );
       *
       *             return tag;
       *         }
       *     } );
       *
       *     // generated html:
       *     //   Test <a href="http://google.com" target="_blank" rel="nofollow">google.com</a>
       *
       *
       * ## Example use with a new tag for the replacement
       *
       *     var html = Autolinker.link( "Test google.com", {
       *         replaceFn : function( match ) {
       *             var tag = new Autolinker.HtmlTag( {
       *                 tagName : 'button',
       *                 attrs   : { 'title': 'Load URL: ' + match.getAnchorHref() },
       *                 innerHtml : 'Load URL: ' + match.getAnchorText()
       *             } );
       *
       *             return tag;
       *         }
       *     } );
       *
       *     // generated html:
       *     //   Test <button title="Load URL: http://google.com">Load URL: google.com</button>
       */
      var HtmlTag = /** @class */ (function () {
          /**
           * @method constructor
           * @param {Object} [cfg] The configuration properties for this class, in an Object (map)
           */
          function HtmlTag(cfg) {
              if (cfg === void 0) { cfg = {}; }
              /**
               * @cfg {String} tagName
               *
               * The tag name. Ex: 'a', 'button', etc.
               *
               * Not required at instantiation time, but should be set using {@link #setTagName} before {@link #toAnchorString}
               * is executed.
               */
              this.tagName = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Object.<String, String>} attrs
               *
               * An key/value Object (map) of attributes to create the tag with. The keys are the attribute names, and the
               * values are the attribute values.
               */
              this.attrs = {}; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {String} innerHTML
               *
               * The inner HTML for the tag.
               */
              this.innerHTML = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @protected
               * @property {RegExp} whitespaceRegex
               *
               * Regular expression used to match whitespace in a string of CSS classes.
               */
              this.whitespaceRegex = /\s+/; // default value just to get the above doc comment in the ES5 output and documentation generator
              this.tagName = cfg.tagName || '';
              this.attrs = cfg.attrs || {};
              this.innerHTML = cfg.innerHtml || cfg.innerHTML || ''; // accept either the camelCased form or the fully capitalized acronym as in the DOM
          }
          /**
           * Sets the tag name that will be used to generate the tag with.
           *
           * @param {String} tagName
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.setTagName = function (tagName) {
              this.tagName = tagName;
              return this;
          };
          /**
           * Retrieves the tag name.
           *
           * @return {String}
           */
          HtmlTag.prototype.getTagName = function () {
              return this.tagName || '';
          };
          /**
           * Sets an attribute on the HtmlTag.
           *
           * @param {String} attrName The attribute name to set.
           * @param {String} attrValue The attribute value to set.
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.setAttr = function (attrName, attrValue) {
              var tagAttrs = this.getAttrs();
              tagAttrs[attrName] = attrValue;
              return this;
          };
          /**
           * Retrieves an attribute from the HtmlTag. If the attribute does not exist, returns `undefined`.
           *
           * @param {String} attrName The attribute name to retrieve.
           * @return {String} The attribute's value, or `undefined` if it does not exist on the HtmlTag.
           */
          HtmlTag.prototype.getAttr = function (attrName) {
              return this.getAttrs()[attrName];
          };
          /**
           * Sets one or more attributes on the HtmlTag.
           *
           * @param {Object.<String, String>} attrs A key/value Object (map) of the attributes to set.
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.setAttrs = function (attrs) {
              Object.assign(this.getAttrs(), attrs);
              return this;
          };
          /**
           * Retrieves the attributes Object (map) for the HtmlTag.
           *
           * @return {Object.<String, String>} A key/value object of the attributes for the HtmlTag.
           */
          HtmlTag.prototype.getAttrs = function () {
              return this.attrs || (this.attrs = {});
          };
          /**
           * Sets the provided `cssClass`, overwriting any current CSS classes on the HtmlTag.
           *
           * @param {String} cssClass One or more space-separated CSS classes to set (overwrite).
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.setClass = function (cssClass) {
              return this.setAttr('class', cssClass);
          };
          /**
           * Convenience method to add one or more CSS classes to the HtmlTag. Will not add duplicate CSS classes.
           *
           * @param {String} cssClass One or more space-separated CSS classes to add.
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.addClass = function (cssClass) {
              var classAttr = this.getClass(), whitespaceRegex = this.whitespaceRegex, classes = (!classAttr) ? [] : classAttr.split(whitespaceRegex), newClasses = cssClass.split(whitespaceRegex), newClass;
              while (newClass = newClasses.shift()) {
                  if (indexOf(classes, newClass) === -1) {
                      classes.push(newClass);
                  }
              }
              this.getAttrs()['class'] = classes.join(" ");
              return this;
          };
          /**
           * Convenience method to remove one or more CSS classes from the HtmlTag.
           *
           * @param {String} cssClass One or more space-separated CSS classes to remove.
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.removeClass = function (cssClass) {
              var classAttr = this.getClass(), whitespaceRegex = this.whitespaceRegex, classes = (!classAttr) ? [] : classAttr.split(whitespaceRegex), removeClasses = cssClass.split(whitespaceRegex), removeClass;
              while (classes.length && (removeClass = removeClasses.shift())) {
                  var idx = indexOf(classes, removeClass);
                  if (idx !== -1) {
                      classes.splice(idx, 1);
                  }
              }
              this.getAttrs()['class'] = classes.join(" ");
              return this;
          };
          /**
           * Convenience method to retrieve the CSS class(es) for the HtmlTag, which will each be separated by spaces when
           * there are multiple.
           *
           * @return {String}
           */
          HtmlTag.prototype.getClass = function () {
              return this.getAttrs()['class'] || "";
          };
          /**
           * Convenience method to check if the tag has a CSS class or not.
           *
           * @param {String} cssClass The CSS class to check for.
           * @return {Boolean} `true` if the HtmlTag has the CSS class, `false` otherwise.
           */
          HtmlTag.prototype.hasClass = function (cssClass) {
              return (' ' + this.getClass() + ' ').indexOf(' ' + cssClass + ' ') !== -1;
          };
          /**
           * Sets the inner HTML for the tag.
           *
           * @param {String} html The inner HTML to set.
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.setInnerHTML = function (html) {
              this.innerHTML = html;
              return this;
          };
          /**
           * Backwards compatibility method name.
           *
           * @param {String} html The inner HTML to set.
           * @return {Autolinker.HtmlTag} This HtmlTag instance, so that method calls may be chained.
           */
          HtmlTag.prototype.setInnerHtml = function (html) {
              return this.setInnerHTML(html);
          };
          /**
           * Retrieves the inner HTML for the tag.
           *
           * @return {String}
           */
          HtmlTag.prototype.getInnerHTML = function () {
              return this.innerHTML || "";
          };
          /**
           * Backward compatibility method name.
           *
           * @return {String}
           */
          HtmlTag.prototype.getInnerHtml = function () {
              return this.getInnerHTML();
          };
          /**
           * Override of superclass method used to generate the HTML string for the tag.
           *
           * @return {String}
           */
          HtmlTag.prototype.toAnchorString = function () {
              var tagName = this.getTagName(), attrsStr = this.buildAttrsStr();
              attrsStr = (attrsStr) ? ' ' + attrsStr : ''; // prepend a space if there are actually attributes
              return ['<', tagName, attrsStr, '>', this.getInnerHtml(), '</', tagName, '>'].join("");
          };
          /**
           * Support method for {@link #toAnchorString}, returns the string space-separated key="value" pairs, used to populate
           * the stringified HtmlTag.
           *
           * @protected
           * @return {String} Example return: `attr1="value1" attr2="value2"`
           */
          HtmlTag.prototype.buildAttrsStr = function () {
              if (!this.attrs)
                  return ""; // no `attrs` Object (map) has been set, return empty string
              var attrs = this.getAttrs(), attrsArr = [];
              for (var prop in attrs) {
                  if (attrs.hasOwnProperty(prop)) {
                      attrsArr.push(prop + '="' + attrs[prop] + '"');
                  }
              }
              return attrsArr.join(" ");
          };
          return HtmlTag;
      }());

      /**
       * Date: 2015-10-05
       * Author: Kasper Søfren <soefritz@gmail.com> (https://github.com/kafoso)
       *
       * A truncation feature, where the ellipsis will be placed at a section within
       * the URL making it still somewhat human readable.
       *
       * @param {String} url						 A URL.
       * @param {Number} truncateLen		 The maximum length of the truncated output URL string.
       * @param {String} ellipsisChars	 The characters to place within the url, e.g. "...".
       * @return {String} The truncated URL.
       */
      function truncateSmart(url, truncateLen, ellipsisChars) {
          var ellipsisLengthBeforeParsing;
          var ellipsisLength;
          if (ellipsisChars == null) {
              ellipsisChars = '&hellip;';
              ellipsisLength = 3;
              ellipsisLengthBeforeParsing = 8;
          }
          else {
              ellipsisLength = ellipsisChars.length;
              ellipsisLengthBeforeParsing = ellipsisChars.length;
          }
          var parse_url = function (url) {
              var urlObj = {};
              var urlSub = url;
              var match = urlSub.match(/^([a-z]+):\/\//i);
              if (match) {
                  urlObj.scheme = match[1];
                  urlSub = urlSub.substr(match[0].length);
              }
              match = urlSub.match(/^(.*?)(?=(\?|#|\/|$))/i);
              if (match) {
                  urlObj.host = match[1];
                  urlSub = urlSub.substr(match[0].length);
              }
              match = urlSub.match(/^\/(.*?)(?=(\?|#|$))/i);
              if (match) {
                  urlObj.path = match[1];
                  urlSub = urlSub.substr(match[0].length);
              }
              match = urlSub.match(/^\?(.*?)(?=(#|$))/i);
              if (match) {
                  urlObj.query = match[1];
                  urlSub = urlSub.substr(match[0].length);
              }
              match = urlSub.match(/^#(.*?)$/i);
              if (match) {
                  urlObj.fragment = match[1];
                  //urlSub = urlSub.substr(match[0].length);  -- not used. Uncomment if adding another block.
              }
              return urlObj;
          };
          var buildUrl = function (urlObj) {
              var url = "";
              if (urlObj.scheme && urlObj.host) {
                  url += urlObj.scheme + "://";
              }
              if (urlObj.host) {
                  url += urlObj.host;
              }
              if (urlObj.path) {
                  url += "/" + urlObj.path;
              }
              if (urlObj.query) {
                  url += "?" + urlObj.query;
              }
              if (urlObj.fragment) {
                  url += "#" + urlObj.fragment;
              }
              return url;
          };
          var buildSegment = function (segment, remainingAvailableLength) {
              var remainingAvailableLengthHalf = remainingAvailableLength / 2, startOffset = Math.ceil(remainingAvailableLengthHalf), endOffset = (-1) * Math.floor(remainingAvailableLengthHalf), end = "";
              if (endOffset < 0) {
                  end = segment.substr(endOffset);
              }
              return segment.substr(0, startOffset) + ellipsisChars + end;
          };
          if (url.length <= truncateLen) {
              return url;
          }
          var availableLength = truncateLen - ellipsisLength;
          var urlObj = parse_url(url);
          // Clean up the URL
          if (urlObj.query) {
              var matchQuery = urlObj.query.match(/^(.*?)(?=(\?|\#))(.*?)$/i);
              if (matchQuery) {
                  // Malformed URL; two or more "?". Removed any content behind the 2nd.
                  urlObj.query = urlObj.query.substr(0, matchQuery[1].length);
                  url = buildUrl(urlObj);
              }
          }
          if (url.length <= truncateLen) {
              return url;
          }
          if (urlObj.host) {
              urlObj.host = urlObj.host.replace(/^www\./, "");
              url = buildUrl(urlObj);
          }
          if (url.length <= truncateLen) {
              return url;
          }
          // Process and build the URL
          var str = "";
          if (urlObj.host) {
              str += urlObj.host;
          }
          if (str.length >= availableLength) {
              if (urlObj.host.length == truncateLen) {
                  return (urlObj.host.substr(0, (truncateLen - ellipsisLength)) + ellipsisChars).substr(0, availableLength + ellipsisLengthBeforeParsing);
              }
              return buildSegment(str, availableLength).substr(0, availableLength + ellipsisLengthBeforeParsing);
          }
          var pathAndQuery = "";
          if (urlObj.path) {
              pathAndQuery += "/" + urlObj.path;
          }
          if (urlObj.query) {
              pathAndQuery += "?" + urlObj.query;
          }
          if (pathAndQuery) {
              if ((str + pathAndQuery).length >= availableLength) {
                  if ((str + pathAndQuery).length == truncateLen) {
                      return (str + pathAndQuery).substr(0, truncateLen);
                  }
                  var remainingAvailableLength = availableLength - str.length;
                  return (str + buildSegment(pathAndQuery, remainingAvailableLength)).substr(0, availableLength + ellipsisLengthBeforeParsing);
              }
              else {
                  str += pathAndQuery;
              }
          }
          if (urlObj.fragment) {
              var fragment = "#" + urlObj.fragment;
              if ((str + fragment).length >= availableLength) {
                  if ((str + fragment).length == truncateLen) {
                      return (str + fragment).substr(0, truncateLen);
                  }
                  var remainingAvailableLength2 = availableLength - str.length;
                  return (str + buildSegment(fragment, remainingAvailableLength2)).substr(0, availableLength + ellipsisLengthBeforeParsing);
              }
              else {
                  str += fragment;
              }
          }
          if (urlObj.scheme && urlObj.host) {
              var scheme = urlObj.scheme + "://";
              if ((str + scheme).length < availableLength) {
                  return (scheme + str).substr(0, truncateLen);
              }
          }
          if (str.length <= truncateLen) {
              return str;
          }
          var end = "";
          if (availableLength > 0) {
              end = str.substr((-1) * Math.floor(availableLength / 2));
          }
          return (str.substr(0, Math.ceil(availableLength / 2)) + ellipsisChars + end).substr(0, availableLength + ellipsisLengthBeforeParsing);
      }

      /**
       * Date: 2015-10-05
       * Author: Kasper Søfren <soefritz@gmail.com> (https://github.com/kafoso)
       *
       * A truncation feature, where the ellipsis will be placed in the dead-center of the URL.
       *
       * @param {String} url             A URL.
       * @param {Number} truncateLen     The maximum length of the truncated output URL string.
       * @param {String} ellipsisChars   The characters to place within the url, e.g. "..".
       * @return {String} The truncated URL.
       */
      function truncateMiddle(url, truncateLen, ellipsisChars) {
          if (url.length <= truncateLen) {
              return url;
          }
          var ellipsisLengthBeforeParsing;
          var ellipsisLength;
          if (ellipsisChars == null) {
              ellipsisChars = '&hellip;';
              ellipsisLengthBeforeParsing = 8;
              ellipsisLength = 3;
          }
          else {
              ellipsisLengthBeforeParsing = ellipsisChars.length;
              ellipsisLength = ellipsisChars.length;
          }
          var availableLength = truncateLen - ellipsisLength;
          var end = "";
          if (availableLength > 0) {
              end = url.substr((-1) * Math.floor(availableLength / 2));
          }
          return (url.substr(0, Math.ceil(availableLength / 2)) + ellipsisChars + end).substr(0, availableLength + ellipsisLengthBeforeParsing);
      }

      /**
       * A truncation feature where the ellipsis will be placed at the end of the URL.
       *
       * @param {String} anchorText
       * @param {Number} truncateLen The maximum length of the truncated output URL string.
       * @param {String} ellipsisChars The characters to place within the url, e.g. "..".
       * @return {String} The truncated URL.
       */
      function truncateEnd(anchorText, truncateLen, ellipsisChars) {
          return ellipsis(anchorText, truncateLen, ellipsisChars);
      }

      /**
       * @protected
       * @class Autolinker.AnchorTagBuilder
       * @extends Object
       *
       * Builds anchor (&lt;a&gt;) tags for the Autolinker utility when a match is
       * found.
       *
       * Normally this class is instantiated, configured, and used internally by an
       * {@link Autolinker} instance, but may actually be used indirectly in a
       * {@link Autolinker#replaceFn replaceFn} to create {@link Autolinker.HtmlTag HtmlTag}
       * instances which may be modified before returning from the
       * {@link Autolinker#replaceFn replaceFn}. For example:
       *
       *     var html = Autolinker.link( "Test google.com", {
       *         replaceFn : function( match ) {
       *             var tag = match.buildTag();  // returns an {@link Autolinker.HtmlTag} instance
       *             tag.setAttr( 'rel', 'nofollow' );
       *
       *             return tag;
       *         }
       *     } );
       *
       *     // generated html:
       *     //   Test <a href="http://google.com" target="_blank" rel="nofollow">google.com</a>
       */
      var AnchorTagBuilder = /** @class */ (function () {
          /**
           * @method constructor
           * @param {Object} [cfg] The configuration options for the AnchorTagBuilder instance, specified in an Object (map).
           */
          function AnchorTagBuilder(cfg) {
              if (cfg === void 0) { cfg = {}; }
              /**
               * @cfg {Boolean} newWindow
               * @inheritdoc Autolinker#newWindow
               */
              this.newWindow = false; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Object} truncate
               * @inheritdoc Autolinker#truncate
               */
              this.truncate = {}; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {String} className
               * @inheritdoc Autolinker#className
               */
              this.className = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              this.newWindow = cfg.newWindow || false;
              this.truncate = cfg.truncate || {};
              this.className = cfg.className || '';
          }
          /**
           * Generates the actual anchor (&lt;a&gt;) tag to use in place of the
           * matched text, via its `match` object.
           *
           * @param {Autolinker.match.Match} match The Match instance to generate an
           *   anchor tag from.
           * @return {Autolinker.HtmlTag} The HtmlTag instance for the anchor tag.
           */
          AnchorTagBuilder.prototype.build = function (match) {
              return new HtmlTag({
                  tagName: 'a',
                  attrs: this.createAttrs(match),
                  innerHtml: this.processAnchorText(match.getAnchorText())
              });
          };
          /**
           * Creates the Object (map) of the HTML attributes for the anchor (&lt;a&gt;)
           *   tag being generated.
           *
           * @protected
           * @param {Autolinker.match.Match} match The Match instance to generate an
           *   anchor tag from.
           * @return {Object} A key/value Object (map) of the anchor tag's attributes.
           */
          AnchorTagBuilder.prototype.createAttrs = function (match) {
              var attrs = {
                  'href': match.getAnchorHref() // we'll always have the `href` attribute
              };
              var cssClass = this.createCssClass(match);
              if (cssClass) {
                  attrs['class'] = cssClass;
              }
              if (this.newWindow) {
                  attrs['target'] = "_blank";
                  attrs['rel'] = "noopener noreferrer"; // Issue #149. See https://mathiasbynens.github.io/rel-noopener/
              }
              if (this.truncate) {
                  if (this.truncate.length && this.truncate.length < match.getAnchorText().length) {
                      attrs['title'] = match.getAnchorHref();
                  }
              }
              return attrs;
          };
          /**
           * Creates the CSS class that will be used for a given anchor tag, based on
           * the `matchType` and the {@link #className} config.
           *
           * Example returns:
           *
           * - ""                                      // no {@link #className}
           * - "myLink myLink-url"                     // url match
           * - "myLink myLink-email"                   // email match
           * - "myLink myLink-phone"                   // phone match
           * - "myLink myLink-hashtag"                 // hashtag match
           * - "myLink myLink-mention myLink-twitter"  // mention match with Twitter service
           *
           * @protected
           * @param {Autolinker.match.Match} match The Match instance to generate an
           *   anchor tag from.
           * @return {String} The CSS class string for the link. Example return:
           *   "myLink myLink-url". If no {@link #className} was configured, returns
           *   an empty string.
           */
          AnchorTagBuilder.prototype.createCssClass = function (match) {
              var className = this.className;
              if (!className) {
                  return "";
              }
              else {
                  var returnClasses = [className], cssClassSuffixes = match.getCssClassSuffixes();
                  for (var i = 0, len = cssClassSuffixes.length; i < len; i++) {
                      returnClasses.push(className + '-' + cssClassSuffixes[i]);
                  }
                  return returnClasses.join(' ');
              }
          };
          /**
           * Processes the `anchorText` by truncating the text according to the
           * {@link #truncate} config.
           *
           * @private
           * @param {String} anchorText The anchor tag's text (i.e. what will be
           *   displayed).
           * @return {String} The processed `anchorText`.
           */
          AnchorTagBuilder.prototype.processAnchorText = function (anchorText) {
              anchorText = this.doTruncate(anchorText);
              return anchorText;
          };
          /**
           * Performs the truncation of the `anchorText` based on the {@link #truncate}
           * option. If the `anchorText` is longer than the length specified by the
           * {@link #truncate} option, the truncation is performed based on the
           * `location` property. See {@link #truncate} for details.
           *
           * @private
           * @param {String} anchorText The anchor tag's text (i.e. what will be
           *   displayed).
           * @return {String} The truncated anchor text.
           */
          AnchorTagBuilder.prototype.doTruncate = function (anchorText) {
              var truncate = this.truncate;
              if (!truncate || !truncate.length)
                  return anchorText;
              var truncateLength = truncate.length, truncateLocation = truncate.location;
              if (truncateLocation === 'smart') {
                  return truncateSmart(anchorText, truncateLength);
              }
              else if (truncateLocation === 'middle') {
                  return truncateMiddle(anchorText, truncateLength);
              }
              else {
                  return truncateEnd(anchorText, truncateLength);
              }
          };
          return AnchorTagBuilder;
      }());

      /**
       * @abstract
       * @class Autolinker.match.Match
       *
       * Represents a match found in an input string which should be Autolinked. A Match object is what is provided in a
       * {@link Autolinker#replaceFn replaceFn}, and may be used to query for details about the match.
       *
       * For example:
       *
       *     var input = "...";  // string with URLs, Email Addresses, and Mentions (Twitter, Instagram, Soundcloud)
       *
       *     var linkedText = Autolinker.link( input, {
       *         replaceFn : function( match ) {
       *             console.log( "href = ", match.getAnchorHref() );
       *             console.log( "text = ", match.getAnchorText() );
       *
       *             switch( match.getType() ) {
       *                 case 'url' :
       *                     console.log( "url: ", match.getUrl() );
       *
       *                 case 'email' :
       *                     console.log( "email: ", match.getEmail() );
       *
       *                 case 'mention' :
       *                     console.log( "mention: ", match.getMention() );
       *             }
       *         }
       *     } );
       *
       * See the {@link Autolinker} class for more details on using the {@link Autolinker#replaceFn replaceFn}.
       */
      var Match = /** @class */ (function () {
          /**
           * @member Autolinker.match.Match
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match
           *   instance, specified in an Object (map).
           */
          function Match(cfg) {
              /**
               * @cfg {Autolinker.AnchorTagBuilder} tagBuilder (required)
               *
               * Reference to the AnchorTagBuilder instance to use to generate an anchor
               * tag for the Match.
               */
              this.__jsduckDummyDocProp = null; // property used just to get the above doc comment into the ES5 output and documentation generator
              /**
               * @cfg {String} matchedText (required)
               *
               * The original text that was matched by the {@link Autolinker.matcher.Matcher}.
               */
              this.matchedText = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Number} offset (required)
               *
               * The offset of where the match was made in the input string.
               */
              this.offset = 0; // default value just to get the above doc comment in the ES5 output and documentation generator
              this.tagBuilder = cfg.tagBuilder;
              this.matchedText = cfg.matchedText;
              this.offset = cfg.offset;
          }
          /**
           * Returns the original text that was matched.
           *
           * @return {String}
           */
          Match.prototype.getMatchedText = function () {
              return this.matchedText;
          };
          /**
           * Sets the {@link #offset} of where the match was made in the input string.
           *
           * A {@link Autolinker.matcher.Matcher} will be fed only HTML text nodes,
           * and will therefore set an original offset that is relative to the HTML
           * text node itself. However, we want this offset to be relative to the full
           * HTML input string, and thus if using {@link Autolinker#parse} (rather
           * than calling a {@link Autolinker.matcher.Matcher} directly), then this
           * offset is corrected after the Matcher itself has done its job.
           *
           * @param {Number} offset
           */
          Match.prototype.setOffset = function (offset) {
              this.offset = offset;
          };
          /**
           * Returns the offset of where the match was made in the input string. This
           * is the 0-based index of the match.
           *
           * @return {Number}
           */
          Match.prototype.getOffset = function () {
              return this.offset;
          };
          /**
           * Returns the CSS class suffix(es) for this match.
           *
           * A CSS class suffix is appended to the {@link Autolinker#className} in
           * the {@link Autolinker.AnchorTagBuilder} when a match is translated into
           * an anchor tag.
           *
           * For example, if {@link Autolinker#className} was configured as 'myLink',
           * and this method returns `[ 'url' ]`, the final class name of the element
           * will become: 'myLink myLink-url'.
           *
           * The match may provide multiple CSS class suffixes to be appended to the
           * {@link Autolinker#className} in order to facilitate better styling
           * options for different match criteria. See {@link Autolinker.match.Mention}
           * for an example.
           *
           * By default, this method returns a single array with the match's
           * {@link #getType type} name, but may be overridden by subclasses.
           *
           * @return {String[]}
           */
          Match.prototype.getCssClassSuffixes = function () {
              return [this.getType()];
          };
          /**
           * Builds and returns an {@link Autolinker.HtmlTag} instance based on the
           * Match.
           *
           * This can be used to easily generate anchor tags from matches, and either
           * return their HTML string, or modify them before doing so.
           *
           * Example Usage:
           *
           *     var tag = match.buildTag();
           *     tag.addClass( 'cordova-link' );
           *     tag.setAttr( 'target', '_system' );
           *
           *     tag.toAnchorString();  // <a href="http://google.com" class="cordova-link" target="_system">Google</a>
           *
           * Example Usage in {@link Autolinker#replaceFn}:
           *
           *     var html = Autolinker.link( "Test google.com", {
           *         replaceFn : function( match ) {
           *             var tag = match.buildTag();  // returns an {@link Autolinker.HtmlTag} instance
           *             tag.setAttr( 'rel', 'nofollow' );
           *
           *             return tag;
           *         }
           *     } );
           *
           *     // generated html:
           *     //   Test <a href="http://google.com" target="_blank" rel="nofollow">google.com</a>
           */
          Match.prototype.buildTag = function () {
              return this.tagBuilder.build(this);
          };
          return Match;
      }());

      /*! *****************************************************************************
      Copyright (c) Microsoft Corporation. All rights reserved.
      Licensed under the Apache License, Version 2.0 (the "License"); you may not use
      this file except in compliance with the License. You may obtain a copy of the
      License at http://www.apache.org/licenses/LICENSE-2.0

      THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
      KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
      WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
      MERCHANTABLITY OR NON-INFRINGEMENT.

      See the Apache Version 2.0 License for specific language governing permissions
      and limitations under the License.
      ***************************************************************************** */
      /* global Reflect, Promise */

      var extendStatics = function(d, b) {
          extendStatics = Object.setPrototypeOf ||
              ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
              function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
          return extendStatics(d, b);
      };

      function __extends(d, b) {
          extendStatics(d, b);
          function __() { this.constructor = d; }
          d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
      }

      var __assign = function() {
          __assign = Object.assign || function __assign(t) {
              for (var s, i = 1, n = arguments.length; i < n; i++) {
                  s = arguments[i];
                  for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p)) t[p] = s[p];
              }
              return t;
          };
          return __assign.apply(this, arguments);
      };

      /**
       * @class Autolinker.match.Email
       * @extends Autolinker.match.Match
       *
       * Represents a Email match found in an input string which should be Autolinked.
       *
       * See this class's superclass ({@link Autolinker.match.Match}) for more details.
       */
      var EmailMatch = /** @class */ (function (_super) {
          __extends(EmailMatch, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match
           *   instance, specified in an Object (map).
           */
          function EmailMatch(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {String} email (required)
               *
               * The email address that was matched.
               */
              _this.email = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              _this.email = cfg.email;
              return _this;
          }
          /**
           * Returns a string name for the type of match that this class represents.
           * For the case of EmailMatch, returns 'email'.
           *
           * @return {String}
           */
          EmailMatch.prototype.getType = function () {
              return 'email';
          };
          /**
           * Returns the email address that was matched.
           *
           * @return {String}
           */
          EmailMatch.prototype.getEmail = function () {
              return this.email;
          };
          /**
           * Returns the anchor href that should be generated for the match.
           *
           * @return {String}
           */
          EmailMatch.prototype.getAnchorHref = function () {
              return 'mailto:' + this.email;
          };
          /**
           * Returns the anchor text that should be generated for the match.
           *
           * @return {String}
           */
          EmailMatch.prototype.getAnchorText = function () {
              return this.email;
          };
          return EmailMatch;
      }(Match));

      /**
       * @class Autolinker.match.Hashtag
       * @extends Autolinker.match.Match
       *
       * Represents a Hashtag match found in an input string which should be
       * Autolinked.
       *
       * See this class's superclass ({@link Autolinker.match.Match}) for more
       * details.
       */
      var HashtagMatch = /** @class */ (function (_super) {
          __extends(HashtagMatch, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match
           *   instance, specified in an Object (map).
           */
          function HashtagMatch(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {String} serviceName
               *
               * The service to point hashtag matches to. See {@link Autolinker#hashtag}
               * for available values.
               */
              _this.serviceName = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {String} hashtag (required)
               *
               * The HashtagMatch that was matched, without the '#'.
               */
              _this.hashtag = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              _this.serviceName = cfg.serviceName;
              _this.hashtag = cfg.hashtag;
              return _this;
          }
          /**
           * Returns a string name for the type of match that this class represents.
           * For the case of HashtagMatch, returns 'hashtag'.
           *
           * @return {String}
           */
          HashtagMatch.prototype.getType = function () {
              return 'hashtag';
          };
          /**
           * Returns the configured {@link #serviceName} to point the HashtagMatch to.
           * Ex: 'facebook', 'twitter'.
           *
           * @return {String}
           */
          HashtagMatch.prototype.getServiceName = function () {
              return this.serviceName;
          };
          /**
           * Returns the matched hashtag, without the '#' character.
           *
           * @return {String}
           */
          HashtagMatch.prototype.getHashtag = function () {
              return this.hashtag;
          };
          /**
           * Returns the anchor href that should be generated for the match.
           *
           * @return {String}
           */
          HashtagMatch.prototype.getAnchorHref = function () {
              var serviceName = this.serviceName, hashtag = this.hashtag;
              switch (serviceName) {
                  case 'twitter':
                      return 'https://twitter.com/hashtag/' + hashtag;
                  case 'facebook':
                      return 'https://www.facebook.com/hashtag/' + hashtag;
                  case 'instagram':
                      return 'https://instagram.com/explore/tags/' + hashtag;
                  default: // Shouldn't happen because Autolinker's constructor should block any invalid values, but just in case.
                      throw new Error('Unknown service name to point hashtag to: ' + serviceName);
              }
          };
          /**
           * Returns the anchor text that should be generated for the match.
           *
           * @return {String}
           */
          HashtagMatch.prototype.getAnchorText = function () {
              return '#' + this.hashtag;
          };
          return HashtagMatch;
      }(Match));

      /**
       * @class Autolinker.match.Mention
       * @extends Autolinker.match.Match
       *
       * Represents a Mention match found in an input string which should be Autolinked.
       *
       * See this class's superclass ({@link Autolinker.match.Match}) for more details.
       */
      var MentionMatch = /** @class */ (function (_super) {
          __extends(MentionMatch, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match
           *   instance, specified in an Object (map).
           */
          function MentionMatch(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {String} serviceName
               *
               * The service to point mention matches to. See {@link Autolinker#mention}
               * for available values.
               */
              _this.serviceName = 'twitter'; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {String} mention (required)
               *
               * The Mention that was matched, without the '@' character.
               */
              _this.mention = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              _this.mention = cfg.mention;
              _this.serviceName = cfg.serviceName;
              return _this;
          }
          /**
           * Returns a string name for the type of match that this class represents.
           * For the case of MentionMatch, returns 'mention'.
           *
           * @return {String}
           */
          MentionMatch.prototype.getType = function () {
              return 'mention';
          };
          /**
           * Returns the mention, without the '@' character.
           *
           * @return {String}
           */
          MentionMatch.prototype.getMention = function () {
              return this.mention;
          };
          /**
           * Returns the configured {@link #serviceName} to point the mention to.
           * Ex: 'instagram', 'twitter', 'soundcloud'.
           *
           * @return {String}
           */
          MentionMatch.prototype.getServiceName = function () {
              return this.serviceName;
          };
          /**
           * Returns the anchor href that should be generated for the match.
           *
           * @return {String}
           */
          MentionMatch.prototype.getAnchorHref = function () {
              switch (this.serviceName) {
                  case 'twitter':
                      return 'https://twitter.com/' + this.mention;
                  case 'instagram':
                      return 'https://instagram.com/' + this.mention;
                  case 'soundcloud':
                      return 'https://soundcloud.com/' + this.mention;
                  default: // Shouldn't happen because Autolinker's constructor should block any invalid values, but just in case.
                      throw new Error('Unknown service name to point mention to: ' + this.serviceName);
              }
          };
          /**
           * Returns the anchor text that should be generated for the match.
           *
           * @return {String}
           */
          MentionMatch.prototype.getAnchorText = function () {
              return '@' + this.mention;
          };
          /**
           * Returns the CSS class suffixes that should be used on a tag built with
           * the match. See {@link Autolinker.match.Match#getCssClassSuffixes} for
           * details.
           *
           * @return {String[]}
           */
          MentionMatch.prototype.getCssClassSuffixes = function () {
              var cssClassSuffixes = _super.prototype.getCssClassSuffixes.call(this), serviceName = this.getServiceName();
              if (serviceName) {
                  cssClassSuffixes.push(serviceName);
              }
              return cssClassSuffixes;
          };
          return MentionMatch;
      }(Match));

      /**
       * @class Autolinker.match.Phone
       * @extends Autolinker.match.Match
       *
       * Represents a Phone number match found in an input string which should be
       * Autolinked.
       *
       * See this class's superclass ({@link Autolinker.match.Match}) for more
       * details.
       */
      var PhoneMatch = /** @class */ (function (_super) {
          __extends(PhoneMatch, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match
           *   instance, specified in an Object (map).
           */
          function PhoneMatch(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @protected
               * @property {String} number (required)
               *
               * The phone number that was matched, without any delimiter characters.
               *
               * Note: This is a string to allow for prefixed 0's.
               */
              _this.number = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @protected
               * @property  {Boolean} plusSign (required)
               *
               * `true` if the matched phone number started with a '+' sign. We'll include
               * it in the `tel:` URL if so, as this is needed for international numbers.
               *
               * Ex: '+1 (123) 456 7879'
               */
              _this.plusSign = false; // default value just to get the above doc comment in the ES5 output and documentation generator
              _this.number = cfg.number;
              _this.plusSign = cfg.plusSign;
              return _this;
          }
          /**
           * Returns a string name for the type of match that this class represents.
           * For the case of PhoneMatch, returns 'phone'.
           *
           * @return {String}
           */
          PhoneMatch.prototype.getType = function () {
              return 'phone';
          };
          /**
           * Returns the phone number that was matched as a string, without any
           * delimiter characters.
           *
           * Note: This is a string to allow for prefixed 0's.
           *
           * @return {String}
           */
          PhoneMatch.prototype.getPhoneNumber = function () {
              return this.number;
          };
          /**
           * Alias of {@link #getPhoneNumber}, returns the phone number that was
           * matched as a string, without any delimiter characters.
           *
           * Note: This is a string to allow for prefixed 0's.
           *
           * @return {String}
           */
          PhoneMatch.prototype.getNumber = function () {
              return this.getPhoneNumber();
          };
          /**
           * Returns the anchor href that should be generated for the match.
           *
           * @return {String}
           */
          PhoneMatch.prototype.getAnchorHref = function () {
              return 'tel:' + (this.plusSign ? '+' : '') + this.number;
          };
          /**
           * Returns the anchor text that should be generated for the match.
           *
           * @return {String}
           */
          PhoneMatch.prototype.getAnchorText = function () {
              return this.matchedText;
          };
          return PhoneMatch;
      }(Match));

      /**
       * @class Autolinker.match.Url
       * @extends Autolinker.match.Match
       *
       * Represents a Url match found in an input string which should be Autolinked.
       *
       * See this class's superclass ({@link Autolinker.match.Match}) for more details.
       */
      var UrlMatch = /** @class */ (function (_super) {
          __extends(UrlMatch, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match
           *   instance, specified in an Object (map).
           */
          function UrlMatch(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {String} url (required)
               *
               * The url that was matched.
               */
              _this.url = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {"scheme"/"www"/"tld"} urlMatchType (required)
               *
               * The type of URL match that this class represents. This helps to determine
               * if the match was made in the original text with a prefixed scheme (ex:
               * 'http://www.google.com'), a prefixed 'www' (ex: 'www.google.com'), or
               * was matched by a known top-level domain (ex: 'google.com').
               */
              _this.urlMatchType = 'scheme'; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} protocolUrlMatch (required)
               *
               * `true` if the URL is a match which already has a protocol (i.e.
               * 'http://'), `false` if the match was from a 'www' or known TLD match.
               */
              _this.protocolUrlMatch = false; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} protocolRelativeMatch (required)
               *
               * `true` if the URL is a protocol-relative match. A protocol-relative match
               * is a URL that starts with '//', and will be either http:// or https://
               * based on the protocol that the site is loaded under.
               */
              _this.protocolRelativeMatch = false; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Object} stripPrefix (required)
               *
               * The Object form of {@link Autolinker#cfg-stripPrefix}.
               */
              _this.stripPrefix = { scheme: true, www: true }; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} stripTrailingSlash (required)
               * @inheritdoc Autolinker#cfg-stripTrailingSlash
               */
              _this.stripTrailingSlash = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} decodePercentEncoding (required)
               * @inheritdoc Autolinker#cfg-decodePercentEncoding
               */
              _this.decodePercentEncoding = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @private
               * @property {RegExp} schemePrefixRegex
               *
               * A regular expression used to remove the 'http://' or 'https://' from
               * URLs.
               */
              _this.schemePrefixRegex = /^(https?:\/\/)?/i;
              /**
               * @private
               * @property {RegExp} wwwPrefixRegex
               *
               * A regular expression used to remove the 'www.' from URLs.
               */
              _this.wwwPrefixRegex = /^(https?:\/\/)?(www\.)?/i;
              /**
               * @private
               * @property {RegExp} protocolRelativeRegex
               *
               * The regular expression used to remove the protocol-relative '//' from the {@link #url} string, for purposes
               * of {@link #getAnchorText}. A protocol-relative URL is, for example, "//yahoo.com"
               */
              _this.protocolRelativeRegex = /^\/\//;
              /**
               * @private
               * @property {Boolean} protocolPrepended
               *
               * Will be set to `true` if the 'http://' protocol has been prepended to the {@link #url} (because the
               * {@link #url} did not have a protocol)
               */
              _this.protocolPrepended = false;
              _this.urlMatchType = cfg.urlMatchType;
              _this.url = cfg.url;
              _this.protocolUrlMatch = cfg.protocolUrlMatch;
              _this.protocolRelativeMatch = cfg.protocolRelativeMatch;
              _this.stripPrefix = cfg.stripPrefix;
              _this.stripTrailingSlash = cfg.stripTrailingSlash;
              _this.decodePercentEncoding = cfg.decodePercentEncoding;
              return _this;
          }
          /**
           * Returns a string name for the type of match that this class represents.
           * For the case of UrlMatch, returns 'url'.
           *
           * @return {String}
           */
          UrlMatch.prototype.getType = function () {
              return 'url';
          };
          /**
           * Returns a string name for the type of URL match that this class
           * represents.
           *
           * This helps to determine if the match was made in the original text with a
           * prefixed scheme (ex: 'http://www.google.com'), a prefixed 'www' (ex:
           * 'www.google.com'), or was matched by a known top-level domain (ex:
           * 'google.com').
           *
           * @return {"scheme"/"www"/"tld"}
           */
          UrlMatch.prototype.getUrlMatchType = function () {
              return this.urlMatchType;
          };
          /**
           * Returns the url that was matched, assuming the protocol to be 'http://' if the original
           * match was missing a protocol.
           *
           * @return {String}
           */
          UrlMatch.prototype.getUrl = function () {
              var url = this.url;
              // if the url string doesn't begin with a protocol, assume 'http://'
              if (!this.protocolRelativeMatch && !this.protocolUrlMatch && !this.protocolPrepended) {
                  url = this.url = 'http://' + url;
                  this.protocolPrepended = true;
              }
              return url;
          };
          /**
           * Returns the anchor href that should be generated for the match.
           *
           * @return {String}
           */
          UrlMatch.prototype.getAnchorHref = function () {
              var url = this.getUrl();
              return url.replace(/&amp;/g, '&'); // any &amp;'s in the URL should be converted back to '&' if they were displayed as &amp; in the source html
          };
          /**
           * Returns the anchor text that should be generated for the match.
           *
           * @return {String}
           */
          UrlMatch.prototype.getAnchorText = function () {
              var anchorText = this.getMatchedText();
              if (this.protocolRelativeMatch) {
                  // Strip off any protocol-relative '//' from the anchor text
                  anchorText = this.stripProtocolRelativePrefix(anchorText);
              }
              if (this.stripPrefix.scheme) {
                  anchorText = this.stripSchemePrefix(anchorText);
              }
              if (this.stripPrefix.www) {
                  anchorText = this.stripWwwPrefix(anchorText);
              }
              if (this.stripTrailingSlash) {
                  anchorText = this.removeTrailingSlash(anchorText); // remove trailing slash, if there is one
              }
              if (this.decodePercentEncoding) {
                  anchorText = this.removePercentEncoding(anchorText);
              }
              return anchorText;
          };
          // ---------------------------------------
          // Utility Functionality
          /**
           * Strips the scheme prefix (such as "http://" or "https://") from the given
           * `url`.
           *
           * @private
           * @param {String} url The text of the anchor that is being generated, for
           *   which to strip off the url scheme.
           * @return {String} The `url`, with the scheme stripped.
           */
          UrlMatch.prototype.stripSchemePrefix = function (url) {
              return url.replace(this.schemePrefixRegex, '');
          };
          /**
           * Strips the 'www' prefix from the given `url`.
           *
           * @private
           * @param {String} url The text of the anchor that is being generated, for
           *   which to strip off the 'www' if it exists.
           * @return {String} The `url`, with the 'www' stripped.
           */
          UrlMatch.prototype.stripWwwPrefix = function (url) {
              return url.replace(this.wwwPrefixRegex, '$1'); // leave any scheme ($1), it one exists
          };
          /**
           * Strips any protocol-relative '//' from the anchor text.
           *
           * @private
           * @param {String} text The text of the anchor that is being generated, for which to strip off the
           *   protocol-relative prefix (such as stripping off "//")
           * @return {String} The `anchorText`, with the protocol-relative prefix stripped.
           */
          UrlMatch.prototype.stripProtocolRelativePrefix = function (text) {
              return text.replace(this.protocolRelativeRegex, '');
          };
          /**
           * Removes any trailing slash from the given `anchorText`, in preparation for the text to be displayed.
           *
           * @private
           * @param {String} anchorText The text of the anchor that is being generated, for which to remove any trailing
           *   slash ('/') that may exist.
           * @return {String} The `anchorText`, with the trailing slash removed.
           */
          UrlMatch.prototype.removeTrailingSlash = function (anchorText) {
              if (anchorText.charAt(anchorText.length - 1) === '/') {
                  anchorText = anchorText.slice(0, -1);
              }
              return anchorText;
          };
          /**
           * Decodes percent-encoded characters from the given `anchorText`, in
           * preparation for the text to be displayed.
           *
           * @private
           * @param {String} anchorText The text of the anchor that is being
           *   generated, for which to decode any percent-encoded characters.
           * @return {String} The `anchorText`, with the percent-encoded characters
           *   decoded.
           */
          UrlMatch.prototype.removePercentEncoding = function (anchorText) {
              // First, convert a few of the known % encodings to the corresponding
              // HTML entities that could accidentally be interpretted as special
              // HTML characters
              var preProcessedEntityAnchorText = anchorText
                  .replace(/%22/gi, '&quot;') // " char
                  .replace(/%26/gi, '&amp;') // & char
                  .replace(/%27/gi, '&#39;') // ' char
                  .replace(/%3C/gi, '&lt;') // < char
                  .replace(/%3E/gi, '&gt;'); // > char
              try {
                  // Now attempt to decode the rest of the anchor text
                  return decodeURIComponent(preProcessedEntityAnchorText);
              }
              catch (e) { // Invalid % escape sequence in the anchor text
                  return preProcessedEntityAnchorText;
              }
          };
          return UrlMatch;
      }(Match));

      /**
       * @abstract
       * @class Autolinker.matcher.Matcher
       *
       * An abstract class and interface for individual matchers to find matches in
       * an input string with linkified versions of them.
       *
       * Note that Matchers do not take HTML into account - they must be fed the text
       * nodes of any HTML string, which is handled by {@link Autolinker#parse}.
       */
      var Matcher = /** @class */ (function () {
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Matcher
           *   instance, specified in an Object (map).
           */
          function Matcher(cfg) {
              /**
               * @cfg {Autolinker.AnchorTagBuilder} tagBuilder (required)
               *
               * Reference to the AnchorTagBuilder instance to use to generate HTML tags
               * for {@link Autolinker.match.Match Matches}.
               */
              this.__jsduckDummyDocProp = null; // property used just to get the above doc comment into the ES5 output and documentation generator
              this.tagBuilder = cfg.tagBuilder;
          }
          return Matcher;
      }());

      /*
       * This file builds and stores a library of the common regular expressions used
       * by the Autolinker utility.
       *
       * Other regular expressions may exist ad-hoc, but these are generally the
       * regular expressions that are shared between source files.
       */
      /**
       * Regular expression to match upper and lowercase ASCII letters
       */
      var letterRe = /[A-Za-z]/;
      /**
       * Regular expression to match ASCII digits
       */
      var digitRe = /[0-9]/;
      /**
       * Regular expression to match whitespace
       */
      var whitespaceRe = /\s/;
      /**
       * Regular expression to match quote characters
       */
      var quoteRe = /['"]/;
      /**
       * Regular expression to match the range of ASCII control characters (0-31), and
       * the backspace char (127)
       */
      var controlCharsRe = /[\x00-\x1F\x7F]/;
      /**
       * The string form of a regular expression that would match all of the
       * alphabetic ("letter") chars in the unicode character set when placed in a
       * RegExp character class (`[]`). This includes all international alphabetic
       * characters.
       *
       * These would be the characters matched by unicode regex engines `\p{L}`
       * escape ("all letters").
       *
       * Taken from the XRegExp library: http://xregexp.com/ (thanks @https://github.com/slevithan)
       * Specifically: http://xregexp.com/v/3.2.0/xregexp-all.js, the 'Letter'
       *   regex's bmp
       *
       * VERY IMPORTANT: This set of characters is defined inside of a Regular
       *   Expression literal rather than a string literal to prevent UglifyJS from
       *   compressing the unicode escape sequences into their actual unicode
       *   characters. If Uglify compresses these into the unicode characters
       *   themselves, this results in the error "Range out of order in character
       *   class" when these characters are used inside of a Regular Expression
       *   character class (`[]`). See usages of this const. Alternatively, we can set
       *   the UglifyJS option `ascii_only` to true for the build, but that doesn't
       *   help others who are pulling in Autolinker into their own build and running
       *   UglifyJS themselves.
       */
      var alphaCharsStr = /A-Za-z\xAA\xB5\xBA\xC0-\xD6\xD8-\xF6\xF8-\u02C1\u02C6-\u02D1\u02E0-\u02E4\u02EC\u02EE\u0370-\u0374\u0376\u0377\u037A-\u037D\u037F\u0386\u0388-\u038A\u038C\u038E-\u03A1\u03A3-\u03F5\u03F7-\u0481\u048A-\u052F\u0531-\u0556\u0559\u0561-\u0587\u05D0-\u05EA\u05F0-\u05F2\u0620-\u064A\u066E\u066F\u0671-\u06D3\u06D5\u06E5\u06E6\u06EE\u06EF\u06FA-\u06FC\u06FF\u0710\u0712-\u072F\u074D-\u07A5\u07B1\u07CA-\u07EA\u07F4\u07F5\u07FA\u0800-\u0815\u081A\u0824\u0828\u0840-\u0858\u08A0-\u08B4\u08B6-\u08BD\u0904-\u0939\u093D\u0950\u0958-\u0961\u0971-\u0980\u0985-\u098C\u098F\u0990\u0993-\u09A8\u09AA-\u09B0\u09B2\u09B6-\u09B9\u09BD\u09CE\u09DC\u09DD\u09DF-\u09E1\u09F0\u09F1\u0A05-\u0A0A\u0A0F\u0A10\u0A13-\u0A28\u0A2A-\u0A30\u0A32\u0A33\u0A35\u0A36\u0A38\u0A39\u0A59-\u0A5C\u0A5E\u0A72-\u0A74\u0A85-\u0A8D\u0A8F-\u0A91\u0A93-\u0AA8\u0AAA-\u0AB0\u0AB2\u0AB3\u0AB5-\u0AB9\u0ABD\u0AD0\u0AE0\u0AE1\u0AF9\u0B05-\u0B0C\u0B0F\u0B10\u0B13-\u0B28\u0B2A-\u0B30\u0B32\u0B33\u0B35-\u0B39\u0B3D\u0B5C\u0B5D\u0B5F-\u0B61\u0B71\u0B83\u0B85-\u0B8A\u0B8E-\u0B90\u0B92-\u0B95\u0B99\u0B9A\u0B9C\u0B9E\u0B9F\u0BA3\u0BA4\u0BA8-\u0BAA\u0BAE-\u0BB9\u0BD0\u0C05-\u0C0C\u0C0E-\u0C10\u0C12-\u0C28\u0C2A-\u0C39\u0C3D\u0C58-\u0C5A\u0C60\u0C61\u0C80\u0C85-\u0C8C\u0C8E-\u0C90\u0C92-\u0CA8\u0CAA-\u0CB3\u0CB5-\u0CB9\u0CBD\u0CDE\u0CE0\u0CE1\u0CF1\u0CF2\u0D05-\u0D0C\u0D0E-\u0D10\u0D12-\u0D3A\u0D3D\u0D4E\u0D54-\u0D56\u0D5F-\u0D61\u0D7A-\u0D7F\u0D85-\u0D96\u0D9A-\u0DB1\u0DB3-\u0DBB\u0DBD\u0DC0-\u0DC6\u0E01-\u0E30\u0E32\u0E33\u0E40-\u0E46\u0E81\u0E82\u0E84\u0E87\u0E88\u0E8A\u0E8D\u0E94-\u0E97\u0E99-\u0E9F\u0EA1-\u0EA3\u0EA5\u0EA7\u0EAA\u0EAB\u0EAD-\u0EB0\u0EB2\u0EB3\u0EBD\u0EC0-\u0EC4\u0EC6\u0EDC-\u0EDF\u0F00\u0F40-\u0F47\u0F49-\u0F6C\u0F88-\u0F8C\u1000-\u102A\u103F\u1050-\u1055\u105A-\u105D\u1061\u1065\u1066\u106E-\u1070\u1075-\u1081\u108E\u10A0-\u10C5\u10C7\u10CD\u10D0-\u10FA\u10FC-\u1248\u124A-\u124D\u1250-\u1256\u1258\u125A-\u125D\u1260-\u1288\u128A-\u128D\u1290-\u12B0\u12B2-\u12B5\u12B8-\u12BE\u12C0\u12C2-\u12C5\u12C8-\u12D6\u12D8-\u1310\u1312-\u1315\u1318-\u135A\u1380-\u138F\u13A0-\u13F5\u13F8-\u13FD\u1401-\u166C\u166F-\u167F\u1681-\u169A\u16A0-\u16EA\u16F1-\u16F8\u1700-\u170C\u170E-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176C\u176E-\u1770\u1780-\u17B3\u17D7\u17DC\u1820-\u1877\u1880-\u1884\u1887-\u18A8\u18AA\u18B0-\u18F5\u1900-\u191E\u1950-\u196D\u1970-\u1974\u1980-\u19AB\u19B0-\u19C9\u1A00-\u1A16\u1A20-\u1A54\u1AA7\u1B05-\u1B33\u1B45-\u1B4B\u1B83-\u1BA0\u1BAE\u1BAF\u1BBA-\u1BE5\u1C00-\u1C23\u1C4D-\u1C4F\u1C5A-\u1C7D\u1C80-\u1C88\u1CE9-\u1CEC\u1CEE-\u1CF1\u1CF5\u1CF6\u1D00-\u1DBF\u1E00-\u1F15\u1F18-\u1F1D\u1F20-\u1F45\u1F48-\u1F4D\u1F50-\u1F57\u1F59\u1F5B\u1F5D\u1F5F-\u1F7D\u1F80-\u1FB4\u1FB6-\u1FBC\u1FBE\u1FC2-\u1FC4\u1FC6-\u1FCC\u1FD0-\u1FD3\u1FD6-\u1FDB\u1FE0-\u1FEC\u1FF2-\u1FF4\u1FF6-\u1FFC\u2071\u207F\u2090-\u209C\u2102\u2107\u210A-\u2113\u2115\u2119-\u211D\u2124\u2126\u2128\u212A-\u212D\u212F-\u2139\u213C-\u213F\u2145-\u2149\u214E\u2183\u2184\u2C00-\u2C2E\u2C30-\u2C5E\u2C60-\u2CE4\u2CEB-\u2CEE\u2CF2\u2CF3\u2D00-\u2D25\u2D27\u2D2D\u2D30-\u2D67\u2D6F\u2D80-\u2D96\u2DA0-\u2DA6\u2DA8-\u2DAE\u2DB0-\u2DB6\u2DB8-\u2DBE\u2DC0-\u2DC6\u2DC8-\u2DCE\u2DD0-\u2DD6\u2DD8-\u2DDE\u2E2F\u3005\u3006\u3031-\u3035\u303B\u303C\u3041-\u3096\u309D-\u309F\u30A1-\u30FA\u30FC-\u30FF\u3105-\u312D\u3131-\u318E\u31A0-\u31BA\u31F0-\u31FF\u3400-\u4DB5\u4E00-\u9FD5\uA000-\uA48C\uA4D0-\uA4FD\uA500-\uA60C\uA610-\uA61F\uA62A\uA62B\uA640-\uA66E\uA67F-\uA69D\uA6A0-\uA6E5\uA717-\uA71F\uA722-\uA788\uA78B-\uA7AE\uA7B0-\uA7B7\uA7F7-\uA801\uA803-\uA805\uA807-\uA80A\uA80C-\uA822\uA840-\uA873\uA882-\uA8B3\uA8F2-\uA8F7\uA8FB\uA8FD\uA90A-\uA925\uA930-\uA946\uA960-\uA97C\uA984-\uA9B2\uA9CF\uA9E0-\uA9E4\uA9E6-\uA9EF\uA9FA-\uA9FE\uAA00-\uAA28\uAA40-\uAA42\uAA44-\uAA4B\uAA60-\uAA76\uAA7A\uAA7E-\uAAAF\uAAB1\uAAB5\uAAB6\uAAB9-\uAABD\uAAC0\uAAC2\uAADB-\uAADD\uAAE0-\uAAEA\uAAF2-\uAAF4\uAB01-\uAB06\uAB09-\uAB0E\uAB11-\uAB16\uAB20-\uAB26\uAB28-\uAB2E\uAB30-\uAB5A\uAB5C-\uAB65\uAB70-\uABE2\uAC00-\uD7A3\uD7B0-\uD7C6\uD7CB-\uD7FB\uF900-\uFA6D\uFA70-\uFAD9\uFB00-\uFB06\uFB13-\uFB17\uFB1D\uFB1F-\uFB28\uFB2A-\uFB36\uFB38-\uFB3C\uFB3E\uFB40\uFB41\uFB43\uFB44\uFB46-\uFBB1\uFBD3-\uFD3D\uFD50-\uFD8F\uFD92-\uFDC7\uFDF0-\uFDFB\uFE70-\uFE74\uFE76-\uFEFC\uFF21-\uFF3A\uFF41-\uFF5A\uFF66-\uFFBE\uFFC2-\uFFC7\uFFCA-\uFFCF\uFFD2-\uFFD7\uFFDA-\uFFDC/
          .source; // see note in above variable description
      /**
       * The string form of a regular expression that would match all emoji characters
       * Source: https://www.regextester.com/106421
       */
      var emojiStr = /\u00a9\u00ae\u2000-\u3300\ud83c\ud000-\udfff\ud83d\ud000-\udfff\ud83e\ud000-\udfff/
          .source;
      /**
       * The string form of a regular expression that would match all of the
       * combining mark characters in the unicode character set when placed in a
       * RegExp character class (`[]`).
       *
       * These would be the characters matched by unicode regex engines `\p{M}`
       * escape ("all marks").
       *
       * Taken from the XRegExp library: http://xregexp.com/ (thanks @https://github.com/slevithan)
       * Specifically: http://xregexp.com/v/3.2.0/xregexp-all.js, the 'Mark'
       *   regex's bmp
       *
       * VERY IMPORTANT: This set of characters is defined inside of a Regular
       *   Expression literal rather than a string literal to prevent UglifyJS from
       *   compressing the unicode escape sequences into their actual unicode
       *   characters. If Uglify compresses these into the unicode characters
       *   themselves, this results in the error "Range out of order in character
       *   class" when these characters are used inside of a Regular Expression
       *   character class (`[]`). See usages of this const. Alternatively, we can set
       *   the UglifyJS option `ascii_only` to true for the build, but that doesn't
       *   help others who are pulling in Autolinker into their own build and running
       *   UglifyJS themselves.
       */
      var marksStr = /\u0300-\u036F\u0483-\u0489\u0591-\u05BD\u05BF\u05C1\u05C2\u05C4\u05C5\u05C7\u0610-\u061A\u064B-\u065F\u0670\u06D6-\u06DC\u06DF-\u06E4\u06E7\u06E8\u06EA-\u06ED\u0711\u0730-\u074A\u07A6-\u07B0\u07EB-\u07F3\u0816-\u0819\u081B-\u0823\u0825-\u0827\u0829-\u082D\u0859-\u085B\u08D4-\u08E1\u08E3-\u0903\u093A-\u093C\u093E-\u094F\u0951-\u0957\u0962\u0963\u0981-\u0983\u09BC\u09BE-\u09C4\u09C7\u09C8\u09CB-\u09CD\u09D7\u09E2\u09E3\u0A01-\u0A03\u0A3C\u0A3E-\u0A42\u0A47\u0A48\u0A4B-\u0A4D\u0A51\u0A70\u0A71\u0A75\u0A81-\u0A83\u0ABC\u0ABE-\u0AC5\u0AC7-\u0AC9\u0ACB-\u0ACD\u0AE2\u0AE3\u0B01-\u0B03\u0B3C\u0B3E-\u0B44\u0B47\u0B48\u0B4B-\u0B4D\u0B56\u0B57\u0B62\u0B63\u0B82\u0BBE-\u0BC2\u0BC6-\u0BC8\u0BCA-\u0BCD\u0BD7\u0C00-\u0C03\u0C3E-\u0C44\u0C46-\u0C48\u0C4A-\u0C4D\u0C55\u0C56\u0C62\u0C63\u0C81-\u0C83\u0CBC\u0CBE-\u0CC4\u0CC6-\u0CC8\u0CCA-\u0CCD\u0CD5\u0CD6\u0CE2\u0CE3\u0D01-\u0D03\u0D3E-\u0D44\u0D46-\u0D48\u0D4A-\u0D4D\u0D57\u0D62\u0D63\u0D82\u0D83\u0DCA\u0DCF-\u0DD4\u0DD6\u0DD8-\u0DDF\u0DF2\u0DF3\u0E31\u0E34-\u0E3A\u0E47-\u0E4E\u0EB1\u0EB4-\u0EB9\u0EBB\u0EBC\u0EC8-\u0ECD\u0F18\u0F19\u0F35\u0F37\u0F39\u0F3E\u0F3F\u0F71-\u0F84\u0F86\u0F87\u0F8D-\u0F97\u0F99-\u0FBC\u0FC6\u102B-\u103E\u1056-\u1059\u105E-\u1060\u1062-\u1064\u1067-\u106D\u1071-\u1074\u1082-\u108D\u108F\u109A-\u109D\u135D-\u135F\u1712-\u1714\u1732-\u1734\u1752\u1753\u1772\u1773\u17B4-\u17D3\u17DD\u180B-\u180D\u1885\u1886\u18A9\u1920-\u192B\u1930-\u193B\u1A17-\u1A1B\u1A55-\u1A5E\u1A60-\u1A7C\u1A7F\u1AB0-\u1ABE\u1B00-\u1B04\u1B34-\u1B44\u1B6B-\u1B73\u1B80-\u1B82\u1BA1-\u1BAD\u1BE6-\u1BF3\u1C24-\u1C37\u1CD0-\u1CD2\u1CD4-\u1CE8\u1CED\u1CF2-\u1CF4\u1CF8\u1CF9\u1DC0-\u1DF5\u1DFB-\u1DFF\u20D0-\u20F0\u2CEF-\u2CF1\u2D7F\u2DE0-\u2DFF\u302A-\u302F\u3099\u309A\uA66F-\uA672\uA674-\uA67D\uA69E\uA69F\uA6F0\uA6F1\uA802\uA806\uA80B\uA823-\uA827\uA880\uA881\uA8B4-\uA8C5\uA8E0-\uA8F1\uA926-\uA92D\uA947-\uA953\uA980-\uA983\uA9B3-\uA9C0\uA9E5\uAA29-\uAA36\uAA43\uAA4C\uAA4D\uAA7B-\uAA7D\uAAB0\uAAB2-\uAAB4\uAAB7\uAAB8\uAABE\uAABF\uAAC1\uAAEB-\uAAEF\uAAF5\uAAF6\uABE3-\uABEA\uABEC\uABED\uFB1E\uFE00-\uFE0F\uFE20-\uFE2F/
          .source; // see note in above variable description
      /**
       * The string form of a regular expression that would match all of the
       * alphabetic ("letter") chars, emoji, and combining marks in the unicode character set
       * when placed in a RegExp character class (`[]`). This includes all
       * international alphabetic characters.
       *
       * These would be the characters matched by unicode regex engines `\p{L}\p{M}`
       * escapes and emoji characters.
       */
      var alphaCharsAndMarksStr = alphaCharsStr + emojiStr + marksStr;
      /**
       * The string form of a regular expression that would match all of the
       * decimal number chars in the unicode character set when placed in a RegExp
       * character class (`[]`).
       *
       * These would be the characters matched by unicode regex engines `\p{Nd}`
       * escape ("all decimal numbers")
       *
       * Taken from the XRegExp library: http://xregexp.com/ (thanks @https://github.com/slevithan)
       * Specifically: http://xregexp.com/v/3.2.0/xregexp-all.js, the 'Decimal_Number'
       *   regex's bmp
       *
       * VERY IMPORTANT: This set of characters is defined inside of a Regular
       *   Expression literal rather than a string literal to prevent UglifyJS from
       *   compressing the unicode escape sequences into their actual unicode
       *   characters. If Uglify compresses these into the unicode characters
       *   themselves, this results in the error "Range out of order in character
       *   class" when these characters are used inside of a Regular Expression
       *   character class (`[]`). See usages of this const. Alternatively, we can set
       *   the UglifyJS option `ascii_only` to true for the build, but that doesn't
       *   help others who are pulling in Autolinker into their own build and running
       *   UglifyJS themselves.
       */
      var decimalNumbersStr = /0-9\u0660-\u0669\u06F0-\u06F9\u07C0-\u07C9\u0966-\u096F\u09E6-\u09EF\u0A66-\u0A6F\u0AE6-\u0AEF\u0B66-\u0B6F\u0BE6-\u0BEF\u0C66-\u0C6F\u0CE6-\u0CEF\u0D66-\u0D6F\u0DE6-\u0DEF\u0E50-\u0E59\u0ED0-\u0ED9\u0F20-\u0F29\u1040-\u1049\u1090-\u1099\u17E0-\u17E9\u1810-\u1819\u1946-\u194F\u19D0-\u19D9\u1A80-\u1A89\u1A90-\u1A99\u1B50-\u1B59\u1BB0-\u1BB9\u1C40-\u1C49\u1C50-\u1C59\uA620-\uA629\uA8D0-\uA8D9\uA900-\uA909\uA9D0-\uA9D9\uA9F0-\uA9F9\uAA50-\uAA59\uABF0-\uABF9\uFF10-\uFF19/
          .source; // see note in above variable description
      /**
       * The string form of a regular expression that would match all of the
       * letters and decimal number chars in the unicode character set when placed in
       * a RegExp character class (`[]`).
       *
       * These would be the characters matched by unicode regex engines
       * `[\p{L}\p{Nd}]` escape ("all letters and decimal numbers")
       */
      var alphaNumericCharsStr = alphaCharsAndMarksStr + decimalNumbersStr;
      /**
       * The string form of a regular expression that would match all of the
       * letters, combining marks, and decimal number chars in the unicode character
       * set when placed in a RegExp character class (`[]`).
       *
       * These would be the characters matched by unicode regex engines
       * `[\p{L}\p{M}\p{Nd}]` escape ("all letters, combining marks, and decimal
       * numbers")
       */
      var alphaNumericAndMarksCharsStr = alphaCharsAndMarksStr + decimalNumbersStr;
      // Simplified IP regular expression
      var ipStr = '(?:[' + decimalNumbersStr + ']{1,3}\\.){3}[' + decimalNumbersStr + ']{1,3}';
      // Protected domain label which do not allow "-" character on the beginning and the end of a single label
      var domainLabelStr = '[' + alphaNumericAndMarksCharsStr + '](?:[' + alphaNumericAndMarksCharsStr + '\\-]{0,61}[' + alphaNumericAndMarksCharsStr + '])?';
      var getDomainLabelStr = function (group) {
          return '(?=(' + domainLabelStr + '))\\' + group;
      };
      /**
       * A function to match domain names of a URL or email address.
       * Ex: 'google', 'yahoo', 'some-other-company', etc.
       */
      var getDomainNameStr = function (group) {
          return '(?:' + getDomainLabelStr(group) + '(?:\\.' + getDomainLabelStr(group + 1) + '){0,126}|' + ipStr + ')';
      };
      /**
       * A regular expression that is simply the character class of the characters
       * that may be used in a domain name, minus the '-' or '.'
       */
      var domainNameCharRegex = new RegExp("[" + alphaNumericAndMarksCharsStr + "]");

      // NOTE: THIS IS A GENERATED FILE
      // To update with the latest TLD list, run `npm run update-tld-regex` or `yarn update-tld-regex` (depending on which you have installed)
      var tldRegex = /(?:xn--vermgensberatung-pwb|xn--vermgensberater-ctb|xn--clchc0ea0b2g2a9gcd|xn--w4r85el8fhu5dnra|northwesternmutual|travelersinsurance|vermögensberatung|xn--3oq18vl8pn36a|xn--5su34j936bgsg|xn--bck1b9a5dre4c|xn--mgbai9azgqp6j|xn--mgberp4a5d4ar|xn--xkc2dl3a5ee0h|vermögensberater|xn--fzys8d69uvgm|xn--mgba7c0bbn0a|xn--xkc2al3hye2a|americanexpress|kerryproperties|sandvikcoromant|xn--i1b6b1a6a2e|xn--kcrx77d1x4a|xn--lgbbat1ad8j|xn--mgba3a4f16a|xn--mgbaakc7dvf|xn--mgbc0a9azcg|xn--nqv7fs00ema|afamilycompany|americanfamily|bananarepublic|cancerresearch|cookingchannel|kerrylogistics|weatherchannel|xn--54b7fta0cc|xn--6qq986b3xl|xn--80aqecdr1a|xn--b4w605ferd|xn--fiq228c5hs|xn--h2breg3eve|xn--jlq61u9w7b|xn--mgba3a3ejt|xn--mgbaam7a8h|xn--mgbayh7gpa|xn--mgbb9fbpob|xn--mgbbh1a71e|xn--mgbca7dzdo|xn--mgbi4ecexp|xn--mgbx4cd0ab|xn--rvc1e0am3e|international|lifeinsurance|spreadbetting|travelchannel|wolterskluwer|xn--eckvdtc9d|xn--fpcrj9c3d|xn--fzc2c9e2c|xn--h2brj9c8c|xn--tiq49xqyj|xn--yfro4i67o|xn--ygbi2ammx|construction|lplfinancial|scholarships|versicherung|xn--3e0b707e|xn--45br5cyl|xn--80adxhks|xn--80asehdb|xn--8y0a063a|xn--gckr3f0f|xn--mgb9awbf|xn--mgbab2bd|xn--mgbgu82a|xn--mgbpl2fh|xn--mgbt3dhd|xn--mk1bu44c|xn--ngbc5azd|xn--ngbe9e0a|xn--ogbpf8fl|xn--qcka1pmc|accountants|barclaycard|blackfriday|blockbuster|bridgestone|calvinklein|contractors|creditunion|engineering|enterprises|foodnetwork|investments|kerryhotels|lamborghini|motorcycles|olayangroup|photography|playstation|productions|progressive|redumbrella|rightathome|williamhill|xn--11b4c3d|xn--1ck2e1b|xn--1qqw23a|xn--2scrj9c|xn--3bst00m|xn--3ds443g|xn--3hcrj9c|xn--42c2d9a|xn--45brj9c|xn--55qw42g|xn--6frz82g|xn--80ao21a|xn--9krt00a|xn--cck2b3b|xn--czr694b|xn--d1acj3b|xn--efvy88h|xn--estv75g|xn--fct429k|xn--fjq720a|xn--flw351e|xn--g2xx48c|xn--gecrj9c|xn--gk3at1e|xn--h2brj9c|xn--hxt814e|xn--imr513n|xn--j6w193g|xn--jvr189m|xn--kprw13d|xn--kpry57d|xn--kpu716f|xn--mgbbh1a|xn--mgbtx2b|xn--mix891f|xn--nyqy26a|xn--otu796d|xn--pbt977c|xn--pgbs0dh|xn--q9jyb4c|xn--rhqv96g|xn--rovu88b|xn--s9brj9c|xn--ses554g|xn--t60b56a|xn--vuq861b|xn--w4rs40l|xn--xhq521b|xn--zfr164b|சிங்கப்பூர்|accountant|apartments|associates|basketball|bnpparibas|boehringer|capitalone|consulting|creditcard|cuisinella|eurovision|extraspace|foundation|healthcare|immobilien|industries|management|mitsubishi|nationwide|newholland|nextdirect|onyourside|properties|protection|prudential|realestate|republican|restaurant|schaeffler|swiftcover|tatamotors|technology|telefonica|university|vistaprint|vlaanderen|volkswagen|xn--30rr7y|xn--3pxu8k|xn--45q11c|xn--4gbrim|xn--55qx5d|xn--5tzm5g|xn--80aswg|xn--90a3ac|xn--9dbq2a|xn--9et52u|xn--c2br7g|xn--cg4bki|xn--czrs0t|xn--czru2d|xn--fiq64b|xn--fiqs8s|xn--fiqz9s|xn--io0a7i|xn--kput3i|xn--mxtq1m|xn--o3cw4h|xn--pssy2u|xn--unup4y|xn--wgbh1c|xn--wgbl6a|xn--y9a3aq|accenture|alfaromeo|allfinanz|amsterdam|analytics|aquarelle|barcelona|bloomberg|christmas|community|directory|education|equipment|fairwinds|financial|firestone|fresenius|frontdoor|fujixerox|furniture|goldpoint|hisamitsu|homedepot|homegoods|homesense|honeywell|institute|insurance|kuokgroup|ladbrokes|lancaster|landrover|lifestyle|marketing|marshalls|melbourne|microsoft|panasonic|passagens|pramerica|richardli|scjohnson|shangrila|solutions|statebank|statefarm|stockholm|travelers|vacations|xn--90ais|xn--c1avg|xn--d1alf|xn--e1a4c|xn--fhbei|xn--j1aef|xn--j1amh|xn--l1acc|xn--ngbrx|xn--nqv7f|xn--p1acf|xn--tckwe|xn--vhquv|yodobashi|abudhabi|airforce|allstate|attorney|barclays|barefoot|bargains|baseball|boutique|bradesco|broadway|brussels|budapest|builders|business|capetown|catering|catholic|chrysler|cipriani|cityeats|cleaning|clinique|clothing|commbank|computer|delivery|deloitte|democrat|diamonds|discount|discover|download|engineer|ericsson|esurance|etisalat|everbank|exchange|feedback|fidelity|firmdale|football|frontier|goodyear|grainger|graphics|guardian|hdfcbank|helsinki|holdings|hospital|infiniti|ipiranga|istanbul|jpmorgan|lighting|lundbeck|marriott|maserati|mckinsey|memorial|merckmsd|mortgage|movistar|observer|partners|pharmacy|pictures|plumbing|property|redstone|reliance|saarland|samsclub|security|services|shopping|showtime|softbank|software|stcgroup|supplies|symantec|training|uconnect|vanguard|ventures|verisign|woodside|xn--90ae|xn--node|xn--p1ai|xn--qxam|yokohama|السعودية|abogado|academy|agakhan|alibaba|android|athleta|auction|audible|auspost|avianca|banamex|bauhaus|bentley|bestbuy|booking|brother|bugatti|capital|caravan|careers|cartier|channel|charity|chintai|citadel|clubmed|college|cologne|comcast|company|compare|contact|cooking|corsica|country|coupons|courses|cricket|cruises|dentist|digital|domains|exposed|express|farmers|fashion|ferrari|ferrero|finance|fishing|fitness|flights|florist|flowers|forsale|frogans|fujitsu|gallery|genting|godaddy|grocery|guitars|hamburg|hangout|hitachi|holiday|hosting|hoteles|hotmail|hyundai|iselect|ismaili|jewelry|juniper|kitchen|komatsu|lacaixa|lancome|lanxess|lasalle|latrobe|leclerc|liaison|limited|lincoln|markets|metlife|monster|netbank|netflix|network|neustar|okinawa|oldnavy|organic|origins|philips|pioneer|politie|realtor|recipes|rentals|reviews|rexroth|samsung|sandvik|schmidt|schwarz|science|shiksha|shriram|singles|staples|starhub|storage|support|surgery|systems|temasek|theater|theatre|tickets|tiffany|toshiba|trading|walmart|wanggou|watches|weather|website|wedding|whoswho|windows|winners|xfinity|yamaxun|youtube|zuerich|католик|اتصالات|الجزائر|العليان|پاکستان|كاثوليك|موبايلي|இந்தியா|abarth|abbott|abbvie|active|africa|agency|airbus|airtel|alipay|alsace|alstom|anquan|aramco|author|bayern|beauty|berlin|bharti|blanco|bostik|boston|broker|camera|career|caseih|casino|center|chanel|chrome|church|circle|claims|clinic|coffee|comsec|condos|coupon|credit|cruise|dating|datsun|dealer|degree|dental|design|direct|doctor|dunlop|dupont|durban|emerck|energy|estate|events|expert|family|flickr|futbol|gallup|garden|george|giving|global|google|gratis|health|hermes|hiphop|hockey|hotels|hughes|imamat|insure|intuit|jaguar|joburg|juegos|kaufen|kinder|kindle|kosher|lancia|latino|lawyer|lefrak|living|locker|london|luxury|madrid|maison|makeup|market|mattel|mobile|mobily|monash|mormon|moscow|museum|mutual|nagoya|natura|nissan|nissay|norton|nowruz|office|olayan|online|oracle|orange|otsuka|pfizer|photos|physio|piaget|pictet|quebec|racing|realty|reisen|repair|report|review|rocher|rogers|ryukyu|safety|sakura|sanofi|school|schule|search|secure|select|shouji|soccer|social|stream|studio|supply|suzuki|swatch|sydney|taipei|taobao|target|tattoo|tennis|tienda|tjmaxx|tkmaxx|toyota|travel|unicom|viajes|viking|villas|virgin|vision|voting|voyage|vuelos|walter|warman|webcam|xihuan|yachts|yandex|zappos|москва|онлайн|ابوظبي|ارامكو|الاردن|المغرب|امارات|فلسطين|مليسيا|भारतम्|இலங்கை|ファッション|actor|adult|aetna|amfam|amica|apple|archi|audio|autos|azure|baidu|beats|bible|bingo|black|boats|bosch|build|canon|cards|chase|cheap|cisco|citic|click|cloud|coach|codes|crown|cymru|dabur|dance|deals|delta|dodge|drive|dubai|earth|edeka|email|epost|epson|faith|fedex|final|forex|forum|gallo|games|gifts|gives|glade|glass|globo|gmail|green|gripe|group|gucci|guide|homes|honda|horse|house|hyatt|ikano|intel|irish|iveco|jetzt|koeln|kyoto|lamer|lease|legal|lexus|lilly|linde|lipsy|lixil|loans|locus|lotte|lotto|lupin|macys|mango|media|miami|money|mopar|movie|nadex|nexus|nikon|ninja|nokia|nowtv|omega|osaka|paris|parts|party|phone|photo|pizza|place|poker|praxi|press|prime|promo|quest|radio|rehab|reise|ricoh|rocks|rodeo|rugby|salon|sener|seven|sharp|shell|shoes|skype|sling|smart|smile|solar|space|sport|stada|store|study|style|sucks|swiss|tatar|tires|tirol|tmall|today|tokyo|tools|toray|total|tours|trade|trust|tunes|tushu|ubank|vegas|video|vodka|volvo|wales|watch|weber|weibo|works|world|xerox|yahoo|zippo|ایران|بازار|بھارت|سودان|سورية|همراه|भारोत|संगठन|বাংলা|భారత్|ഭാരതം|嘉里大酒店|aarp|able|adac|aero|aigo|akdn|ally|amex|arab|army|arpa|arte|asda|asia|audi|auto|baby|band|bank|bbva|beer|best|bike|bing|blog|blue|bofa|bond|book|buzz|cafe|call|camp|care|cars|casa|case|cash|cbre|cern|chat|citi|city|club|cool|coop|cyou|data|date|dclk|deal|dell|desi|diet|dish|docs|doha|duck|duns|dvag|erni|fage|fail|fans|farm|fast|fiat|fido|film|fire|fish|flir|food|ford|free|fund|game|gbiz|gent|ggee|gift|gmbh|gold|golf|goog|guge|guru|hair|haus|hdfc|help|here|hgtv|host|hsbc|icbc|ieee|imdb|immo|info|itau|java|jeep|jobs|jprs|kddi|kiwi|kpmg|kred|land|lego|lgbt|lidl|life|like|limo|link|live|loan|loft|love|ltda|luxe|maif|meet|meme|menu|mini|mint|mobi|moda|moto|name|navy|news|next|nico|nike|ollo|open|page|pars|pccw|pics|ping|pink|play|plus|pohl|porn|post|prod|prof|qpon|raid|read|reit|rent|rest|rich|rmit|room|rsvp|ruhr|safe|sale|sarl|save|saxo|scor|scot|seat|seek|sexy|shaw|shia|shop|show|silk|sina|site|skin|sncf|sohu|song|sony|spot|star|surf|talk|taxi|team|tech|teva|tiaa|tips|town|toys|tube|vana|visa|viva|vivo|vote|voto|wang|weir|wien|wiki|wine|work|xbox|yoga|zara|zero|zone|дети|сайт|بارت|بيتك|ڀارت|تونس|شبكة|عراق|عمان|موقع|भारत|ভারত|ভাৰত|ਭਾਰਤ|ભારત|ଭାରତ|ಭಾರತ|ලංකා|グーグル|クラウド|ポイント|大众汽车|组织机构|電訊盈科|香格里拉|aaa|abb|abc|aco|ads|aeg|afl|aig|anz|aol|app|art|aws|axa|bar|bbc|bbt|bcg|bcn|bet|bid|bio|biz|bms|bmw|bnl|bom|boo|bot|box|buy|bzh|cab|cal|cam|car|cat|cba|cbn|cbs|ceb|ceo|cfa|cfd|com|crs|csc|dad|day|dds|dev|dhl|diy|dnp|dog|dot|dtv|dvr|eat|eco|edu|esq|eus|fan|fit|fly|foo|fox|frl|ftr|fun|fyi|gal|gap|gdn|gea|gle|gmo|gmx|goo|gop|got|gov|hbo|hiv|hkt|hot|how|ibm|ice|icu|ifm|inc|ing|ink|int|ist|itv|jcb|jcp|jio|jll|jmp|jnj|jot|joy|kfh|kia|kim|kpn|krd|lat|law|lds|llc|lol|lpl|ltd|man|map|mba|med|men|mil|mit|mlb|mls|mma|moe|moi|mom|mov|msd|mtn|mtr|nab|nba|nec|net|new|nfl|ngo|nhk|now|nra|nrw|ntt|nyc|obi|off|one|ong|onl|ooo|org|ott|ovh|pay|pet|phd|pid|pin|pnc|pro|pru|pub|pwc|qvc|red|ren|ril|rio|rip|run|rwe|sap|sas|sbi|sbs|sca|scb|ses|sew|sex|sfr|ski|sky|soy|srl|srt|stc|tab|tax|tci|tdk|tel|thd|tjx|top|trv|tui|tvs|ubs|uno|uol|ups|vet|vig|vin|vip|wed|win|wme|wow|wtc|wtf|xin|xxx|xyz|you|yun|zip|бел|ком|қаз|мкд|мон|орг|рус|срб|укр|հայ|קום|عرب|قطر|كوم|مصر|कॉम|नेट|คอม|ไทย|ストア|セール|みんな|中文网|天主教|我爱你|新加坡|淡马锡|诺基亚|飞利浦|ac|ad|ae|af|ag|ai|al|am|ao|aq|ar|as|at|au|aw|ax|az|ba|bb|bd|be|bf|bg|bh|bi|bj|bm|bn|bo|br|bs|bt|bv|bw|by|bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|cr|cu|cv|cw|cx|cy|cz|de|dj|dk|dm|do|dz|ec|ee|eg|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gg|gh|gi|gl|gm|gn|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie|il|im|in|io|iq|ir|is|it|je|jm|jo|jp|ke|kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly|ma|mc|md|me|mg|mh|mk|ml|mm|mn|mo|mp|mq|mr|ms|mt|mu|mv|mw|mx|my|mz|na|nc|ne|nf|ng|ni|nl|no|np|nr|nu|nz|om|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|ps|pt|pw|py|qa|re|ro|rs|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|sk|sl|sm|sn|so|sr|st|su|sv|sx|sy|sz|tc|td|tf|tg|th|tj|tk|tl|tm|tn|to|tr|tt|tv|tw|tz|ua|ug|uk|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye|yt|za|zm|zw|ελ|бг|ею|рф|გე|닷넷|닷컴|삼성|한국|コム|世界|中信|中国|中國|企业|佛山|信息|健康|八卦|公司|公益|台湾|台灣|商城|商店|商标|嘉里|在线|大拿|娱乐|家電|工行|广东|微博|慈善|手机|手表|招聘|政务|政府|新闻|时尚|書籍|机构|游戏|澳門|点看|珠宝|移动|网址|网店|网站|网络|联通|谷歌|购物|通販|集团|食品|餐厅|香港)/;

      // For debugging: search for other "For debugging" lines
      // import CliTable from 'cli-table';
      /**
       * @class Autolinker.matcher.Email
       * @extends Autolinker.matcher.Matcher
       *
       * Matcher to find email matches in an input string.
       *
       * See this class's superclass ({@link Autolinker.matcher.Matcher}) for more details.
       */
      var EmailMatcher = /** @class */ (function (_super) {
          __extends(EmailMatcher, _super);
          function EmailMatcher() {
              var _this = _super !== null && _super.apply(this, arguments) || this;
              /**
               * Valid characters that can be used in the "local" part of an email address,
               * i.e. the "name" part of "name@site.com"
               */
              _this.localPartCharRegex = new RegExp("[" + alphaNumericAndMarksCharsStr + "!#$%&'*+/=?^_`{|}~-]");
              /**
               * Stricter TLD regex which adds a beginning and end check to ensure
               * the string is a valid TLD
               */
              _this.strictTldRegex = new RegExp("^" + tldRegex.source + "$");
              return _this;
          }
          /**
           * @inheritdoc
           */
          EmailMatcher.prototype.parseMatches = function (text) {
              var tagBuilder = this.tagBuilder, localPartCharRegex = this.localPartCharRegex, strictTldRegex = this.strictTldRegex, matches = [], len = text.length, noCurrentEmailMatch = new CurrentEmailMatch();
              // for matching a 'mailto:' prefix
              var mailtoTransitions = {
                  'm': 'a',
                  'a': 'i',
                  'i': 'l',
                  'l': 't',
                  't': 'o',
                  'o': ':',
              };
              var charIdx = 0, state = 0 /* NonEmailMatch */, currentEmailMatch = noCurrentEmailMatch;
              // For debugging: search for other "For debugging" lines
              // const table = new CliTable( {
              // 	head: [ 'charIdx', 'char', 'state', 'charIdx', 'currentEmailAddress.idx', 'hasDomainDot' ]
              // } );
              while (charIdx < len) {
                  var char = text.charAt(charIdx);
                  // For debugging: search for other "For debugging" lines
                  // table.push(
                  // 	[ charIdx, char, State[ state ], charIdx, currentEmailAddress.idx, currentEmailAddress.hasDomainDot ]
                  // );
                  switch (state) {
                      case 0 /* NonEmailMatch */:
                          stateNonEmailAddress(char);
                          break;
                      case 1 /* Mailto */:
                          stateMailTo(text.charAt(charIdx - 1), char);
                          break;
                      case 2 /* LocalPart */:
                          stateLocalPart(char);
                          break;
                      case 3 /* LocalPartDot */:
                          stateLocalPartDot(char);
                          break;
                      case 4 /* AtSign */:
                          stateAtSign(char);
                          break;
                      case 5 /* DomainChar */:
                          stateDomainChar(char);
                          break;
                      case 6 /* DomainHyphen */:
                          stateDomainHyphen(char);
                          break;
                      case 7 /* DomainDot */:
                          stateDomainDot(char);
                          break;
                      default:
                          throwUnhandledCaseError(state);
                  }
                  // For debugging: search for other "For debugging" lines
                  // table.push(
                  // 	[ charIdx, char, State[ state ], charIdx, currentEmailAddress.idx, currentEmailAddress.hasDomainDot ]
                  // );
                  charIdx++;
              }
              // Capture any valid match at the end of the string
              captureMatchIfValidAndReset();
              // For debugging: search for other "For debugging" lines
              //console.log( '\n' + table.toString() );
              return matches;
              // Handles the state when we're not in an email address
              function stateNonEmailAddress(char) {
                  if (char === 'm') {
                      beginEmailMatch(1 /* Mailto */);
                  }
                  else if (localPartCharRegex.test(char)) {
                      beginEmailMatch();
                  }
              }
              // Handles if we're reading a 'mailto:' prefix on the string
              function stateMailTo(prevChar, char) {
                  if (prevChar === ':') {
                      // We've reached the end of the 'mailto:' prefix
                      if (localPartCharRegex.test(char)) {
                          state = 2 /* LocalPart */;
                          currentEmailMatch = new CurrentEmailMatch(__assign({}, currentEmailMatch, { hasMailtoPrefix: true }));
                      }
                      else {
                          // we've matched 'mailto:' but didn't get anything meaningful
                          // immediately afterwards (for example, we encountered a
                          // space character, or an '@' character which formed 'mailto:@'
                          resetToNonEmailMatchState();
                      }
                  }
                  else if (mailtoTransitions[prevChar] === char) ;
                  else if (localPartCharRegex.test(char)) {
                      // We we're reading a prefix of 'mailto:', but encountered a
                      // different character that didn't continue the prefix
                      state = 2 /* LocalPart */;
                  }
                  else if (char === '.') {
                      // We we're reading a prefix of 'mailto:', but encountered a
                      // dot character
                      state = 3 /* LocalPartDot */;
                  }
                  else if (char === '@') {
                      // We we're reading a prefix of 'mailto:', but encountered a
                      // an @ character
                      state = 4 /* AtSign */;
                  }
                  else {
                      // not an email address character, return to "NonEmailAddress" state
                      resetToNonEmailMatchState();
                  }
              }
              // Handles the state when we're currently in the "local part" of an
              // email address (as opposed to the "domain part")
              function stateLocalPart(char) {
                  if (char === '.') {
                      state = 3 /* LocalPartDot */;
                  }
                  else if (char === '@') {
                      state = 4 /* AtSign */;
                  }
                  else if (localPartCharRegex.test(char)) ;
                  else {
                      // not an email address character, return to "NonEmailAddress" state
                      resetToNonEmailMatchState();
                  }
              }
              // Handles the state where we've read
              function stateLocalPartDot(char) {
                  if (char === '.') {
                      // We read a second '.' in a row, not a valid email address
                      // local part
                      resetToNonEmailMatchState();
                  }
                  else if (char === '@') {
                      // We read the '@' character immediately after a dot ('.'), not
                      // an email address
                      resetToNonEmailMatchState();
                  }
                  else if (localPartCharRegex.test(char)) {
                      state = 2 /* LocalPart */;
                  }
                  else {
                      // Anything else, not an email address
                      resetToNonEmailMatchState();
                  }
              }
              function stateAtSign(char) {
                  if (domainNameCharRegex.test(char)) {
                      state = 5 /* DomainChar */;
                  }
                  else {
                      // Anything else, not an email address
                      resetToNonEmailMatchState();
                  }
              }
              function stateDomainChar(char) {
                  if (char === '.') {
                      state = 7 /* DomainDot */;
                  }
                  else if (char === '-') {
                      state = 6 /* DomainHyphen */;
                  }
                  else if (domainNameCharRegex.test(char)) ;
                  else {
                      // Anything else, we potentially matched if the criteria has
                      // been met
                      captureMatchIfValidAndReset();
                  }
              }
              function stateDomainHyphen(char) {
                  if (char === '-' || char === '.') {
                      // Not valid to have two hyphens ("--") or hypen+dot ("-.")
                      captureMatchIfValidAndReset();
                  }
                  else if (domainNameCharRegex.test(char)) {
                      state = 5 /* DomainChar */;
                  }
                  else {
                      // Anything else
                      captureMatchIfValidAndReset();
                  }
              }
              function stateDomainDot(char) {
                  if (char === '.' || char === '-') {
                      // not valid to have two dots ("..") or dot+hypen (".-")
                      captureMatchIfValidAndReset();
                  }
                  else if (domainNameCharRegex.test(char)) {
                      state = 5 /* DomainChar */;
                      // After having read a '.' and then a valid domain character,
                      // we now know that the domain part of the email is valid, and
                      // we have found at least a partial EmailMatch (however, the
                      // email address may have additional characters from this point)
                      currentEmailMatch = new CurrentEmailMatch(__assign({}, currentEmailMatch, { hasDomainDot: true }));
                  }
                  else {
                      // Anything else
                      captureMatchIfValidAndReset();
                  }
              }
              function beginEmailMatch(newState) {
                  if (newState === void 0) { newState = 2 /* LocalPart */; }
                  state = newState;
                  currentEmailMatch = new CurrentEmailMatch({ idx: charIdx });
              }
              function resetToNonEmailMatchState() {
                  state = 0 /* NonEmailMatch */;
                  currentEmailMatch = noCurrentEmailMatch;
              }
              /*
               * Captures the current email address as an EmailMatch if it's valid,
               * and resets the state to read another email address.
               */
              function captureMatchIfValidAndReset() {
                  if (currentEmailMatch.hasDomainDot) { // we need at least one dot in the domain to be considered a valid email address
                      var matchedText = text.slice(currentEmailMatch.idx, charIdx);
                      // If we read a '.' or '-' char that ended the email address
                      // (valid domain name characters, but only valid email address
                      // characters if they are followed by something else), strip
                      // it off now
                      if (/[-.]$/.test(matchedText)) {
                          matchedText = matchedText.slice(0, -1);
                      }
                      var emailAddress = currentEmailMatch.hasMailtoPrefix
                          ? matchedText.slice('mailto:'.length)
                          : matchedText;
                      // if the email address has a valid TLD, add it to the list of matches
                      if (doesEmailHaveValidTld(emailAddress)) {
                          matches.push(new EmailMatch({
                              tagBuilder: tagBuilder,
                              matchedText: matchedText,
                              offset: currentEmailMatch.idx,
                              email: emailAddress
                          }));
                      }
                  }
                  resetToNonEmailMatchState();
                  /**
                   * Determines if the given email address has a valid TLD or not
                   * @param {string} emailAddress - email address
                   * @return {Boolean} - true is email have valid TLD, false otherwise
                   */
                  function doesEmailHaveValidTld(emailAddress) {
                      var emailAddressTld = emailAddress.split('.').pop() || '';
                      var emailAddressNormalized = emailAddressTld.toLowerCase();
                      var isValidTld = strictTldRegex.test(emailAddressNormalized);
                      return isValidTld;
                  }
              }
          };
          return EmailMatcher;
      }(Matcher));
      var CurrentEmailMatch = /** @class */ (function () {
          function CurrentEmailMatch(cfg) {
              if (cfg === void 0) { cfg = {}; }
              this.idx = cfg.idx !== undefined ? cfg.idx : -1;
              this.hasMailtoPrefix = !!cfg.hasMailtoPrefix;
              this.hasDomainDot = !!cfg.hasDomainDot;
          }
          return CurrentEmailMatch;
      }());

      /**
       * @private
       * @class Autolinker.matcher.UrlMatchValidator
       * @singleton
       *
       * Used by Autolinker to filter out false URL positives from the
       * {@link Autolinker.matcher.Url UrlMatcher}.
       *
       * Due to the limitations of regular expressions (including the missing feature
       * of look-behinds in JS regular expressions), we cannot always determine the
       * validity of a given match. This class applies a bit of additional logic to
       * filter out any false positives that have been matched by the
       * {@link Autolinker.matcher.Url UrlMatcher}.
       */
      var UrlMatchValidator = /** @class */ (function () {
          function UrlMatchValidator() {
          }
          /**
           * Determines if a given URL match found by the {@link Autolinker.matcher.Url UrlMatcher}
           * is valid. Will return `false` for:
           *
           * 1) URL matches which do not have at least have one period ('.') in the
           *    domain name (effectively skipping over matches like "abc:def").
           *    However, URL matches with a protocol will be allowed (ex: 'http://localhost')
           * 2) URL matches which do not have at least one word character in the
           *    domain name (effectively skipping over matches like "git:1.0").
           * 3) A protocol-relative url match (a URL beginning with '//') whose
           *    previous character is a word character (effectively skipping over
           *    strings like "abc//google.com")
           *
           * Otherwise, returns `true`.
           *
           * @param {String} urlMatch The matched URL, if there was one. Will be an
           *   empty string if the match is not a URL match.
           * @param {String} protocolUrlMatch The match URL string for a protocol
           *   match. Ex: 'http://yahoo.com'. This is used to match something like
           *   'http://localhost', where we won't double check that the domain name
           *   has at least one '.' in it.
           * @return {Boolean} `true` if the match given is valid and should be
           *   processed, or `false` if the match is invalid and/or should just not be
           *   processed.
           */
          UrlMatchValidator.isValid = function (urlMatch, protocolUrlMatch) {
              if ((protocolUrlMatch && !this.isValidUriScheme(protocolUrlMatch)) ||
                  this.urlMatchDoesNotHaveProtocolOrDot(urlMatch, protocolUrlMatch) || // At least one period ('.') must exist in the URL match for us to consider it an actual URL, *unless* it was a full protocol match (like 'http://localhost')
                  (this.urlMatchDoesNotHaveAtLeastOneWordChar(urlMatch, protocolUrlMatch) && // At least one letter character must exist in the domain name after a protocol match. Ex: skip over something like "git:1.0"
                      !this.isValidIpAddress(urlMatch)) || // Except if it's an IP address
                  this.containsMultipleDots(urlMatch)) {
                  return false;
              }
              return true;
          };
          UrlMatchValidator.isValidIpAddress = function (uriSchemeMatch) {
              var newRegex = new RegExp(this.hasFullProtocolRegex.source + this.ipRegex.source);
              var uriScheme = uriSchemeMatch.match(newRegex);
              return uriScheme !== null;
          };
          UrlMatchValidator.containsMultipleDots = function (urlMatch) {
              var stringBeforeSlash = urlMatch;
              if (this.hasFullProtocolRegex.test(urlMatch)) {
                  stringBeforeSlash = urlMatch.split('://')[1];
              }
              return stringBeforeSlash.split('/')[0].indexOf("..") > -1;
          };
          /**
           * Determines if the URI scheme is a valid scheme to be autolinked. Returns
           * `false` if the scheme is 'javascript:' or 'vbscript:'
           *
           * @private
           * @param {String} uriSchemeMatch The match URL string for a full URI scheme
           *   match. Ex: 'http://yahoo.com' or 'mailto:a@a.com'.
           * @return {Boolean} `true` if the scheme is a valid one, `false` otherwise.
           */
          UrlMatchValidator.isValidUriScheme = function (uriSchemeMatch) {
              var uriSchemeMatchArr = uriSchemeMatch.match(this.uriSchemeRegex), uriScheme = uriSchemeMatchArr && uriSchemeMatchArr[0].toLowerCase();
              return (uriScheme !== 'javascript:' && uriScheme !== 'vbscript:');
          };
          /**
           * Determines if a URL match does not have either:
           *
           * a) a full protocol (i.e. 'http://'), or
           * b) at least one dot ('.') in the domain name (for a non-full-protocol
           *    match).
           *
           * Either situation is considered an invalid URL (ex: 'git:d' does not have
           * either the '://' part, or at least one dot in the domain name. If the
           * match was 'git:abc.com', we would consider this valid.)
           *
           * @private
           * @param {String} urlMatch The matched URL, if there was one. Will be an
           *   empty string if the match is not a URL match.
           * @param {String} protocolUrlMatch The match URL string for a protocol
           *   match. Ex: 'http://yahoo.com'. This is used to match something like
           *   'http://localhost', where we won't double check that the domain name
           *   has at least one '.' in it.
           * @return {Boolean} `true` if the URL match does not have a full protocol,
           *   or at least one dot ('.') in a non-full-protocol match.
           */
          UrlMatchValidator.urlMatchDoesNotHaveProtocolOrDot = function (urlMatch, protocolUrlMatch) {
              return (!!urlMatch && (!protocolUrlMatch || !this.hasFullProtocolRegex.test(protocolUrlMatch)) && urlMatch.indexOf('.') === -1);
          };
          /**
           * Determines if a URL match does not have at least one word character after
           * the protocol (i.e. in the domain name).
           *
           * At least one letter character must exist in the domain name after a
           * protocol match. Ex: skip over something like "git:1.0"
           *
           * @private
           * @param {String} urlMatch The matched URL, if there was one. Will be an
           *   empty string if the match is not a URL match.
           * @param {String} protocolUrlMatch The match URL string for a protocol
           *   match. Ex: 'http://yahoo.com'. This is used to know whether or not we
           *   have a protocol in the URL string, in order to check for a word
           *   character after the protocol separator (':').
           * @return {Boolean} `true` if the URL match does not have at least one word
           *   character in it after the protocol, `false` otherwise.
           */
          UrlMatchValidator.urlMatchDoesNotHaveAtLeastOneWordChar = function (urlMatch, protocolUrlMatch) {
              if (urlMatch && protocolUrlMatch) {
                  return !this.hasWordCharAfterProtocolRegex.test(urlMatch);
              }
              else {
                  return false;
              }
          };
          /**
           * Regex to test for a full protocol, with the two trailing slashes. Ex: 'http://'
           *
           * @private
           * @property {RegExp} hasFullProtocolRegex
           */
          UrlMatchValidator.hasFullProtocolRegex = /^[A-Za-z][-.+A-Za-z0-9]*:\/\//;
          /**
           * Regex to find the URI scheme, such as 'mailto:'.
           *
           * This is used to filter out 'javascript:' and 'vbscript:' schemes.
           *
           * @private
           * @property {RegExp} uriSchemeRegex
           */
          UrlMatchValidator.uriSchemeRegex = /^[A-Za-z][-.+A-Za-z0-9]*:/;
          /**
           * Regex to determine if at least one word char exists after the protocol (i.e. after the ':')
           *
           * @private
           * @property {RegExp} hasWordCharAfterProtocolRegex
           */
          UrlMatchValidator.hasWordCharAfterProtocolRegex = new RegExp(":[^\\s]*?[" + alphaCharsStr + "]");
          /**
           * Regex to determine if the string is a valid IP address
           *
           * @private
           * @property {RegExp} ipRegex
           */
          UrlMatchValidator.ipRegex = /[0-9][0-9]?[0-9]?\.[0-9][0-9]?[0-9]?\.[0-9][0-9]?[0-9]?\.[0-9][0-9]?[0-9]?(:[0-9]*)?\/?$/;
          return UrlMatchValidator;
      }());

      /**
       * @class Autolinker.matcher.Url
       * @extends Autolinker.matcher.Matcher
       *
       * Matcher to find URL matches in an input string.
       *
       * See this class's superclass ({@link Autolinker.matcher.Matcher}) for more details.
       */
      var UrlMatcher = /** @class */ (function (_super) {
          __extends(UrlMatcher, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match instance,
           *   specified in an Object (map).
           */
          function UrlMatcher(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {Object} stripPrefix (required)
               *
               * The Object form of {@link Autolinker#cfg-stripPrefix}.
               */
              _this.stripPrefix = { scheme: true, www: true }; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} stripTrailingSlash (required)
               * @inheritdoc Autolinker#stripTrailingSlash
               */
              _this.stripTrailingSlash = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} decodePercentEncoding (required)
               * @inheritdoc Autolinker#decodePercentEncoding
               */
              _this.decodePercentEncoding = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @protected
               * @property {RegExp} matcherRegex
               *
               * The regular expression to match URLs with an optional scheme, port
               * number, path, query string, and hash anchor.
               *
               * Example matches:
               *
               *     http://google.com
               *     www.google.com
               *     google.com/path/to/file?q1=1&q2=2#myAnchor
               *
               *
               * This regular expression will have the following capturing groups:
               *
               * 1.  Group that matches a scheme-prefixed URL (i.e. 'http://google.com').
               *     This is used to match scheme URLs with just a single word, such as
               *     'http://localhost', where we won't double check that the domain name
               *     has at least one dot ('.') in it.
               * 2.  Group that matches a 'www.' prefixed URL. This is only matched if the
               *     'www.' text was not prefixed by a scheme (i.e.: not prefixed by
               *     'http://', 'ftp:', etc.)
               * 3.  A protocol-relative ('//') match for the case of a 'www.' prefixed
               *     URL. Will be an empty string if it is not a protocol-relative match.
               *     We need to know the character before the '//' in order to determine
               *     if it is a valid match or the // was in a string we don't want to
               *     auto-link.
               * 4.  Group that matches a known TLD (top level domain), when a scheme
               *     or 'www.'-prefixed domain is not matched.
               * 5.  A protocol-relative ('//') match for the case of a known TLD prefixed
               *     URL. Will be an empty string if it is not a protocol-relative match.
               *     See #3 for more info.
               */
              _this.matcherRegex = (function () {
                  var schemeRegex = /(?:[A-Za-z][-.+A-Za-z0-9]{0,63}:(?![A-Za-z][-.+A-Za-z0-9]{0,63}:\/\/)(?!\d+\/?)(?:\/\/)?)/, // match protocol, allow in format "http://" or "mailto:". However, do not match the first part of something like 'link:http://www.google.com' (i.e. don't match "link:"). Also, make sure we don't interpret 'google.com:8000' as if 'google.com' was a protocol here (i.e. ignore a trailing port number in this regex)
                  wwwRegex = /(?:www\.)/, // starting with 'www.'
                  // Allow optional path, query string, and hash anchor, not ending in the following characters: "?!:,.;"
                  // http://blog.codinghorror.com/the-problem-with-urls/
                  urlSuffixRegex = new RegExp('[/?#](?:[' + alphaNumericAndMarksCharsStr + '\\-+&@#/%=~_()|\'$*\\[\\]?!:,.;\u2713]*[' + alphaNumericAndMarksCharsStr + '\\-+&@#/%=~_()|\'$*\\[\\]\u2713])?');
                  return new RegExp([
                      '(?:',
                      '(',
                      schemeRegex.source,
                      getDomainNameStr(2),
                      ')',
                      '|',
                      '(',
                      '(//)?',
                      wwwRegex.source,
                      getDomainNameStr(6),
                      ')',
                      '|',
                      '(',
                      '(//)?',
                      getDomainNameStr(10) + '\\.',
                      tldRegex.source,
                      '(?![-' + alphaNumericCharsStr + '])',
                      ')',
                      ')',
                      '(?::[0-9]+)?',
                      '(?:' + urlSuffixRegex.source + ')?' // match for path, query string, and/or hash anchor - optional
                  ].join(""), 'gi');
              })();
              /**
               * A regular expression to use to check the character before a protocol-relative
               * URL match. We don't want to match a protocol-relative URL if it is part
               * of another word.
               *
               * For example, we want to match something like "Go to: //google.com",
               * but we don't want to match something like "abc//google.com"
               *
               * This regular expression is used to test the character before the '//'.
               *
               * @protected
               * @type {RegExp} wordCharRegExp
               */
              _this.wordCharRegExp = new RegExp('[' + alphaNumericAndMarksCharsStr + ']');
              _this.stripPrefix = cfg.stripPrefix;
              _this.stripTrailingSlash = cfg.stripTrailingSlash;
              _this.decodePercentEncoding = cfg.decodePercentEncoding;
              return _this;
          }
          /**
           * @inheritdoc
           */
          UrlMatcher.prototype.parseMatches = function (text) {
              var matcherRegex = this.matcherRegex, stripPrefix = this.stripPrefix, stripTrailingSlash = this.stripTrailingSlash, decodePercentEncoding = this.decodePercentEncoding, tagBuilder = this.tagBuilder, matches = [], match;
              var _loop_1 = function () {
                  var matchStr = match[0], schemeUrlMatch = match[1], wwwUrlMatch = match[4], wwwProtocolRelativeMatch = match[5],
                  //tldUrlMatch = match[ 8 ],  -- not needed at the moment
                  tldProtocolRelativeMatch = match[9], offset = match.index, protocolRelativeMatch = wwwProtocolRelativeMatch || tldProtocolRelativeMatch, prevChar = text.charAt(offset - 1);
                  if (!UrlMatchValidator.isValid(matchStr, schemeUrlMatch)) {
                      return "continue";
                  }
                  // If the match is preceded by an '@' character, then it is either
                  // an email address or a username. Skip these types of matches.
                  if (offset > 0 && prevChar === '@') {
                      return "continue";
                  }
                  // If it's a protocol-relative '//' match, but the character before the '//'
                  // was a word character (i.e. a letter/number), then we found the '//' in the
                  // middle of another word (such as "asdf//asdf.com"). In this case, skip the
                  // match.
                  if (offset > 0 && protocolRelativeMatch && this_1.wordCharRegExp.test(prevChar)) {
                      return "continue";
                  }
                  // If the URL ends with a question mark, don't include the question
                  // mark as part of the URL. We'll assume the question mark was the
                  // end of a sentence, such as: "Going to google.com?"
                  if (/\?$/.test(matchStr)) {
                      matchStr = matchStr.substr(0, matchStr.length - 1);
                  }
                  // Handle a closing parenthesis or square bracket at the end of the
                  // match, and exclude it if there is not a matching open parenthesis
                  // or square bracket in the match itself.
                  if (this_1.matchHasUnbalancedClosingParen(matchStr)) {
                      matchStr = matchStr.substr(0, matchStr.length - 1); // remove the trailing ")"
                  }
                  else {
                      // Handle an invalid character after the TLD
                      var pos = this_1.matchHasInvalidCharAfterTld(matchStr, schemeUrlMatch);
                      if (pos > -1) {
                          matchStr = matchStr.substr(0, pos); // remove the trailing invalid chars
                      }
                  }
                  // The autolinker accepts many characters in a url's scheme (like `fake://test.com`).
                  // However, in cases where a URL is missing whitespace before an obvious link,
                  // (for example: `nowhitespacehttp://www.test.com`), we only want the match to start
                  // at the http:// part. We will check if the match contains a common scheme and then
                  // shift the match to start from there.
                  var foundCommonScheme = ['http://', 'https://'].find(function (commonScheme) { return !!schemeUrlMatch && schemeUrlMatch.indexOf(commonScheme) !== -1; });
                  if (foundCommonScheme) {
                      // If we found an overmatched URL, we want to find the index
                      // of where the match should start and shift the match to
                      // start from the beginning of the common scheme
                      var indexOfSchemeStart = matchStr.indexOf(foundCommonScheme);
                      matchStr = matchStr.substr(indexOfSchemeStart);
                      schemeUrlMatch = schemeUrlMatch.substr(indexOfSchemeStart);
                      offset = offset + indexOfSchemeStart;
                  }
                  var urlMatchType = schemeUrlMatch ? 'scheme' : (wwwUrlMatch ? 'www' : 'tld'), protocolUrlMatch = !!schemeUrlMatch;
                  matches.push(new UrlMatch({
                      tagBuilder: tagBuilder,
                      matchedText: matchStr,
                      offset: offset,
                      urlMatchType: urlMatchType,
                      url: matchStr,
                      protocolUrlMatch: protocolUrlMatch,
                      protocolRelativeMatch: !!protocolRelativeMatch,
                      stripPrefix: stripPrefix,
                      stripTrailingSlash: stripTrailingSlash,
                      decodePercentEncoding: decodePercentEncoding,
                  }));
              };
              var this_1 = this;
              while ((match = matcherRegex.exec(text)) !== null) {
                  _loop_1();
              }
              return matches;
          };
          /**
           * Determines if a match found has an unmatched closing parenthesis or
           * square bracket. If so, the parenthesis or square bracket will be removed
           * from the match itself, and appended after the generated anchor tag.
           *
           * A match may have an extra closing parenthesis at the end of the match
           * because the regular expression must include parenthesis for URLs such as
           * "wikipedia.com/something_(disambiguation)", which should be auto-linked.
           *
           * However, an extra parenthesis *will* be included when the URL itself is
           * wrapped in parenthesis, such as in the case of:
           *     "(wikipedia.com/something_(disambiguation))"
           * In this case, the last closing parenthesis should *not* be part of the
           * URL itself, and this method will return `true`.
           *
           * For square brackets in URLs such as in PHP arrays, the same behavior as
           * parenthesis discussed above should happen:
           *     "[http://www.example.com/foo.php?bar[]=1&bar[]=2&bar[]=3]"
           * The closing square bracket should not be part of the URL itself, and this
           * method will return `true`.
           *
           * @protected
           * @param {String} matchStr The full match string from the {@link #matcherRegex}.
           * @return {Boolean} `true` if there is an unbalanced closing parenthesis or
           *   square bracket at the end of the `matchStr`, `false` otherwise.
           */
          UrlMatcher.prototype.matchHasUnbalancedClosingParen = function (matchStr) {
              var endChar = matchStr.charAt(matchStr.length - 1);
              var startChar;
              if (endChar === ')') {
                  startChar = '(';
              }
              else if (endChar === ']') {
                  startChar = '[';
              }
              else {
                  return false; // not a close parenthesis or square bracket
              }
              // Find if there are the same number of open braces as close braces in
              // the URL string, minus the last character (which we have already
              // determined to be either ')' or ']'
              var numOpenBraces = 0;
              for (var i = 0, len = matchStr.length - 1; i < len; i++) {
                  var char = matchStr.charAt(i);
                  if (char === startChar) {
                      numOpenBraces++;
                  }
                  else if (char === endChar) {
                      numOpenBraces = Math.max(numOpenBraces - 1, 0);
                  }
              }
              // If the number of open braces matches the number of close braces in
              // the URL minus the last character, then the match has *unbalanced*
              // braces because of the last character. Example of unbalanced braces
              // from the regex match:
              //     "http://example.com?a[]=1]"
              if (numOpenBraces === 0) {
                  return true;
              }
              return false;
          };
          /**
           * Determine if there's an invalid character after the TLD in a URL. Valid
           * characters after TLD are ':/?#'. Exclude scheme matched URLs from this
           * check.
           *
           * @protected
           * @param {String} urlMatch The matched URL, if there was one. Will be an
           *   empty string if the match is not a URL match.
           * @param {String} schemeUrlMatch The match URL string for a scheme
           *   match. Ex: 'http://yahoo.com'. This is used to match something like
           *   'http://localhost', where we won't double check that the domain name
           *   has at least one '.' in it.
           * @return {Number} the position where the invalid character was found. If
           *   no such character was found, returns -1
           */
          UrlMatcher.prototype.matchHasInvalidCharAfterTld = function (urlMatch, schemeUrlMatch) {
              if (!urlMatch) {
                  return -1;
              }
              var offset = 0;
              if (schemeUrlMatch) {
                  offset = urlMatch.indexOf(':');
                  urlMatch = urlMatch.slice(offset);
              }
              var re = new RegExp("^((.?\/\/)?[-." + alphaNumericAndMarksCharsStr + "]*[-" + alphaNumericAndMarksCharsStr + "]\\.[-" + alphaNumericAndMarksCharsStr + "]+)");
              var res = re.exec(urlMatch);
              if (res === null) {
                  return -1;
              }
              offset += res[1].length;
              urlMatch = urlMatch.slice(res[1].length);
              if (/^[^-.A-Za-z0-9:\/?#]/.test(urlMatch)) {
                  return offset;
              }
              return -1;
          };
          return UrlMatcher;
      }(Matcher));

      /**
       * @class Autolinker.matcher.Hashtag
       * @extends Autolinker.matcher.Matcher
       *
       * Matcher to find HashtagMatch matches in an input string.
       */
      var HashtagMatcher = /** @class */ (function (_super) {
          __extends(HashtagMatcher, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match instance,
           *   specified in an Object (map).
           */
          function HashtagMatcher(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {String} serviceName
               *
               * The service to point hashtag matches to. See {@link Autolinker#hashtag}
               * for available values.
               */
              _this.serviceName = 'twitter'; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * The regular expression to match Hashtags. Example match:
               *
               *     #asdf
               *
               * @protected
               * @property {RegExp} matcherRegex
               */
              _this.matcherRegex = new RegExp("#[_" + alphaNumericAndMarksCharsStr + "]{1,139}(?![_" + alphaNumericAndMarksCharsStr + "])", 'g'); // lookahead used to make sure we don't match something above 139 characters
              /**
               * The regular expression to use to check the character before a username match to
               * make sure we didn't accidentally match an email address.
               *
               * For example, the string "asdf@asdf.com" should not match "@asdf" as a username.
               *
               * @protected
               * @property {RegExp} nonWordCharRegex
               */
              _this.nonWordCharRegex = new RegExp('[^' + alphaNumericAndMarksCharsStr + ']');
              _this.serviceName = cfg.serviceName;
              return _this;
          }
          /**
           * @inheritdoc
           */
          HashtagMatcher.prototype.parseMatches = function (text) {
              var matcherRegex = this.matcherRegex, nonWordCharRegex = this.nonWordCharRegex, serviceName = this.serviceName, tagBuilder = this.tagBuilder, matches = [], match;
              while ((match = matcherRegex.exec(text)) !== null) {
                  var offset = match.index, prevChar = text.charAt(offset - 1);
                  // If we found the match at the beginning of the string, or we found the match
                  // and there is a whitespace char in front of it (meaning it is not a '#' char
                  // in the middle of a word), then it is a hashtag match.
                  if (offset === 0 || nonWordCharRegex.test(prevChar)) {
                      var matchedText = match[0], hashtag = match[0].slice(1); // strip off the '#' character at the beginning
                      matches.push(new HashtagMatch({
                          tagBuilder: tagBuilder,
                          matchedText: matchedText,
                          offset: offset,
                          serviceName: serviceName,
                          hashtag: hashtag
                      }));
                  }
              }
              return matches;
          };
          return HashtagMatcher;
      }(Matcher));

      /**
       * @class Autolinker.matcher.Phone
       * @extends Autolinker.matcher.Matcher
       *
       * Matcher to find Phone number matches in an input string.
       *
       * See this class's superclass ({@link Autolinker.matcher.Matcher}) for more
       * details.
       */
      var PhoneMatcher = /** @class */ (function (_super) {
          __extends(PhoneMatcher, _super);
          function PhoneMatcher() {
              var _this = _super !== null && _super.apply(this, arguments) || this;
              /**
               * The regular expression to match Phone numbers. Example match:
               *
               *     (123) 456-7890
               *
               * This regular expression has the following capturing groups:
               *
               * 1 or 2. The prefixed '+' sign, if there is one.
               *
               * @protected
               * @property {RegExp} matcherRegex
               */
              _this.matcherRegex = /(?:(?:(?:(\+)?\d{1,3}[-\040.]?)?\(?\d{3}\)?[-\040.]?\d{3}[-\040.]?\d{4})|(?:(\+)(?:9[976]\d|8[987530]\d|6[987]\d|5[90]\d|42\d|3[875]\d|2[98654321]\d|9[8543210]|8[6421]|6[6543210]|5[87654321]|4[987654310]|3[9643210]|2[70]|7|1)[-\040.]?(?:\d[-\040.]?){6,12}\d+))([,;]+[0-9]+#?)*/g;
              return _this;
          }
          // ex: (123) 456-7890, 123 456 7890, 123-456-7890, +18004441234,,;,10226420346#,
          // +1 (800) 444 1234, 10226420346#, 1-800-444-1234,1022,64,20346#
          /**
           * @inheritdoc
           */
          PhoneMatcher.prototype.parseMatches = function (text) {
              var matcherRegex = this.matcherRegex, tagBuilder = this.tagBuilder, matches = [], match;
              while ((match = matcherRegex.exec(text)) !== null) {
                  // Remove non-numeric values from phone number string
                  var matchedText = match[0], cleanNumber = matchedText.replace(/[^0-9,;#]/g, ''), // strip out non-digit characters exclude comma semicolon and #
                  plusSign = !!(match[1] || match[2]), // match[ 1 ] or match[ 2 ] is the prefixed plus sign, if there is one
                  before = match.index == 0 ? '' : text.substr(match.index - 1, 1), after = text.substr(match.index + matchedText.length, 1), contextClear = !before.match(/\d/) && !after.match(/\d/);
                  if (this.testMatch(match[3]) && this.testMatch(matchedText) && contextClear) {
                      matches.push(new PhoneMatch({
                          tagBuilder: tagBuilder,
                          matchedText: matchedText,
                          offset: match.index,
                          number: cleanNumber,
                          plusSign: plusSign
                      }));
                  }
              }
              return matches;
          };
          PhoneMatcher.prototype.testMatch = function (text) {
              return /\D/.test(text);
          };
          return PhoneMatcher;
      }(Matcher));

      /**
       * @class Autolinker.matcher.Mention
       * @extends Autolinker.matcher.Matcher
       *
       * Matcher to find/replace username matches in an input string.
       */
      var MentionMatcher = /** @class */ (function (_super) {
          __extends(MentionMatcher, _super);
          /**
           * @method constructor
           * @param {Object} cfg The configuration properties for the Match instance,
           *   specified in an Object (map).
           */
          function MentionMatcher(cfg) {
              var _this = _super.call(this, cfg) || this;
              /**
               * @cfg {'twitter'/'instagram'/'soundcloud'} protected
               *
               * The name of service to link @mentions to.
               *
               * Valid values are: 'twitter', 'instagram', or 'soundcloud'
               */
              _this.serviceName = 'twitter'; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * Hash of regular expression to match username handles. Example match:
               *
               *     @asdf
               *
               * @private
               * @property {Object} matcherRegexes
               */
              _this.matcherRegexes = {
                  'twitter': new RegExp("@[_" + alphaNumericAndMarksCharsStr + "]{1,50}(?![_" + alphaNumericAndMarksCharsStr + "])", 'g'),
                  'instagram': new RegExp("@[_." + alphaNumericAndMarksCharsStr + "]{1,30}(?![_" + alphaNumericAndMarksCharsStr + "])", 'g'),
                  'soundcloud': new RegExp("@[-_." + alphaNumericAndMarksCharsStr + "]{1,50}(?![-_" + alphaNumericAndMarksCharsStr + "])", 'g') // lookahead used to make sure we don't match something above 50 characters
              };
              /**
               * The regular expression to use to check the character before a username match to
               * make sure we didn't accidentally match an email address.
               *
               * For example, the string "asdf@asdf.com" should not match "@asdf" as a username.
               *
               * @private
               * @property {RegExp} nonWordCharRegex
               */
              _this.nonWordCharRegex = new RegExp('[^' + alphaNumericAndMarksCharsStr + ']');
              _this.serviceName = cfg.serviceName;
              return _this;
          }
          /**
           * @inheritdoc
           */
          MentionMatcher.prototype.parseMatches = function (text) {
              var serviceName = this.serviceName, matcherRegex = this.matcherRegexes[this.serviceName], nonWordCharRegex = this.nonWordCharRegex, tagBuilder = this.tagBuilder, matches = [], match;
              if (!matcherRegex) {
                  return matches;
              }
              while ((match = matcherRegex.exec(text)) !== null) {
                  var offset = match.index, prevChar = text.charAt(offset - 1);
                  // If we found the match at the beginning of the string, or we found the match
                  // and there is a whitespace char in front of it (meaning it is not an email
                  // address), then it is a username match.
                  if (offset === 0 || nonWordCharRegex.test(prevChar)) {
                      var matchedText = match[0].replace(/\.+$/g, ''), // strip off trailing .
                      mention = matchedText.slice(1); // strip off the '@' character at the beginning
                      matches.push(new MentionMatch({
                          tagBuilder: tagBuilder,
                          matchedText: matchedText,
                          offset: offset,
                          serviceName: serviceName,
                          mention: mention
                      }));
                  }
              }
              return matches;
          };
          return MentionMatcher;
      }(Matcher));

      // For debugging: search for other "For debugging" lines
      // import CliTable from 'cli-table';
      /**
       * Parses an HTML string, calling the callbacks to notify of tags and text.
       *
       * ## History
       *
       * This file previously used a regular expression to find html tags in the input
       * text. Unfortunately, we ran into a bunch of catastrophic backtracking issues
       * with certain input text, causing Autolinker to either hang or just take a
       * really long time to parse the string.
       *
       * The current code is intended to be a O(n) algorithm that walks through
       * the string in one pass, and tries to be as cheap as possible. We don't need
       * to implement the full HTML spec, but rather simply determine where the string
       * looks like an HTML tag, and where it looks like text (so that we can autolink
       * that).
       *
       * This state machine parser is intended just to be a simple but performant
       * parser of HTML for the subset of requirements we have. We simply need to:
       *
       * 1. Determine where HTML tags are
       * 2. Determine the tag name (Autolinker specifically only cares about <a>,
       *    <script>, and <style> tags, so as not to link any text within them)
       *
       * We don't need to:
       *
       * 1. Create a parse tree
       * 2. Auto-close tags with invalid markup
       * 3. etc.
       *
       * The other intention behind this is that we didn't want to add external
       * dependencies on the Autolinker utility which would increase its size. For
       * instance, adding htmlparser2 adds 125kb to the minified output file,
       * increasing its final size from 47kb to 172kb (at the time of writing). It
       * also doesn't work exactly correctly, treating the string "<3 blah blah blah"
       * as an HTML tag.
       *
       * Reference for HTML spec:
       *
       *     https://www.w3.org/TR/html51/syntax.html#sec-tokenization
       *
       * @param {String} html The HTML to parse
       * @param {Object} callbacks
       * @param {Function} callbacks.onOpenTag Callback function to call when an open
       *   tag is parsed. Called with the tagName as its argument.
       * @param {Function} callbacks.onCloseTag Callback function to call when a close
       *   tag is parsed. Called with the tagName as its argument. If a self-closing
       *   tag is found, `onCloseTag` is called immediately after `onOpenTag`.
       * @param {Function} callbacks.onText Callback function to call when text (i.e
       *   not an HTML tag) is parsed. Called with the text (string) as its first
       *   argument, and offset (number) into the string as its second.
       */
      function parseHtml(html, _a) {
          var onOpenTag = _a.onOpenTag, onCloseTag = _a.onCloseTag, onText = _a.onText, onComment = _a.onComment, onDoctype = _a.onDoctype;
          var noCurrentTag = new CurrentTag();
          var charIdx = 0, len = html.length, state = 0 /* Data */, currentDataIdx = 0, // where the current data start index is
          currentTag = noCurrentTag; // describes the current tag that is being read
          // For debugging: search for other "For debugging" lines
          // const table = new CliTable( {
          // 	head: [ 'charIdx', 'char', 'state', 'currentDataIdx', 'currentOpenTagIdx', 'tag.type' ]
          // } );
          while (charIdx < len) {
              var char = html.charAt(charIdx);
              // For debugging: search for other "For debugging" lines
              // ALSO: Temporarily remove the 'const' keyword on the State enum
              // table.push(
              // 	[ charIdx, char, State[ state ], currentDataIdx, currentTag.idx, currentTag.idx === -1 ? '' : currentTag.type ]
              // );
              switch (state) {
                  case 0 /* Data */:
                      stateData(char);
                      break;
                  case 1 /* TagOpen */:
                      stateTagOpen(char);
                      break;
                  case 2 /* EndTagOpen */:
                      stateEndTagOpen(char);
                      break;
                  case 3 /* TagName */:
                      stateTagName(char);
                      break;
                  case 4 /* BeforeAttributeName */:
                      stateBeforeAttributeName(char);
                      break;
                  case 5 /* AttributeName */:
                      stateAttributeName(char);
                      break;
                  case 6 /* AfterAttributeName */:
                      stateAfterAttributeName(char);
                      break;
                  case 7 /* BeforeAttributeValue */:
                      stateBeforeAttributeValue(char);
                      break;
                  case 8 /* AttributeValueDoubleQuoted */:
                      stateAttributeValueDoubleQuoted(char);
                      break;
                  case 9 /* AttributeValueSingleQuoted */:
                      stateAttributeValueSingleQuoted(char);
                      break;
                  case 10 /* AttributeValueUnquoted */:
                      stateAttributeValueUnquoted(char);
                      break;
                  case 11 /* AfterAttributeValueQuoted */:
                      stateAfterAttributeValueQuoted(char);
                      break;
                  case 12 /* SelfClosingStartTag */:
                      stateSelfClosingStartTag(char);
                      break;
                  case 13 /* MarkupDeclarationOpenState */:
                      stateMarkupDeclarationOpen();
                      break;
                  case 14 /* CommentStart */:
                      stateCommentStart(char);
                      break;
                  case 15 /* CommentStartDash */:
                      stateCommentStartDash(char);
                      break;
                  case 16 /* Comment */:
                      stateComment(char);
                      break;
                  case 17 /* CommentEndDash */:
                      stateCommentEndDash(char);
                      break;
                  case 18 /* CommentEnd */:
                      stateCommentEnd(char);
                      break;
                  case 19 /* CommentEndBang */:
                      stateCommentEndBang(char);
                      break;
                  case 20 /* Doctype */:
                      stateDoctype(char);
                      break;
                  default:
                      throwUnhandledCaseError(state);
              }
              // For debugging: search for other "For debugging" lines
              // ALSO: Temporarily remove the 'const' keyword on the State enum
              // table.push(
              // 	[ charIdx, char, State[ state ], currentDataIdx, currentTag.idx, currentTag.idx === -1 ? '' : currentTag.type ]
              // );
              charIdx++;
          }
          if (currentDataIdx < charIdx) {
              emitText();
          }
          // For debugging: search for other "For debugging" lines
          // console.log( '\n' + table.toString() );
          // Called when non-tags are being read (i.e. the text around HTML †ags)
          // https://www.w3.org/TR/html51/syntax.html#data-state
          function stateData(char) {
              if (char === '<') {
                  startNewTag();
              }
          }
          // Called after a '<' is read from the Data state
          // https://www.w3.org/TR/html51/syntax.html#tag-open-state
          function stateTagOpen(char) {
              if (char === '!') {
                  state = 13 /* MarkupDeclarationOpenState */;
              }
              else if (char === '/') {
                  state = 2 /* EndTagOpen */;
                  currentTag = new CurrentTag(__assign({}, currentTag, { isClosing: true }));
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else if (letterRe.test(char)) {
                  // tag name start (and no '/' read)
                  state = 3 /* TagName */;
                  currentTag = new CurrentTag(__assign({}, currentTag, { isOpening: true }));
              }
              else {
                  // Any other
                  state = 0 /* Data */;
                  currentTag = noCurrentTag;
              }
          }
          // After a '<x', '</x' sequence is read (where 'x' is a letter character),
          // this is to continue reading the tag name
          // https://www.w3.org/TR/html51/syntax.html#tag-name-state
          function stateTagName(char) {
              if (whitespaceRe.test(char)) {
                  currentTag = new CurrentTag(__assign({}, currentTag, { name: captureTagName() }));
                  state = 4 /* BeforeAttributeName */;
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else if (char === '/') {
                  currentTag = new CurrentTag(__assign({}, currentTag, { name: captureTagName() }));
                  state = 12 /* SelfClosingStartTag */;
              }
              else if (char === '>') {
                  currentTag = new CurrentTag(__assign({}, currentTag, { name: captureTagName() }));
                  emitTagAndPreviousTextNode(); // resets to Data state as well
              }
              else if (!letterRe.test(char) && !digitRe.test(char) && char !== ':') {
                  // Anything else that does not form an html tag. Note: the colon
                  // character is accepted for XML namespaced tags
                  resetToDataState();
              }
          }
          // Called after the '/' is read from a '</' sequence
          // https://www.w3.org/TR/html51/syntax.html#end-tag-open-state
          function stateEndTagOpen(char) {
              if (char === '>') { // parse error. Encountered "</>". Skip it without treating as a tag
                  resetToDataState();
              }
              else if (letterRe.test(char)) {
                  state = 3 /* TagName */;
              }
              else {
                  // some other non-tag-like character, don't treat this as a tag
                  resetToDataState();
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#before-attribute-name-state
          function stateBeforeAttributeName(char) {
              if (whitespaceRe.test(char)) ;
              else if (char === '/') {
                  state = 12 /* SelfClosingStartTag */;
              }
              else if (char === '>') {
                  emitTagAndPreviousTextNode(); // resets to Data state as well
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else if (char === "=" || quoteRe.test(char) || controlCharsRe.test(char)) {
                  // "Parse error" characters that, according to the spec, should be
                  // appended to the attribute name, but we'll treat these characters
                  // as not forming a real HTML tag
                  resetToDataState();
              }
              else {
                  // Any other char, start of a new attribute name
                  state = 5 /* AttributeName */;
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#attribute-name-state
          function stateAttributeName(char) {
              if (whitespaceRe.test(char)) {
                  state = 6 /* AfterAttributeName */;
              }
              else if (char === '/') {
                  state = 12 /* SelfClosingStartTag */;
              }
              else if (char === '=') {
                  state = 7 /* BeforeAttributeValue */;
              }
              else if (char === '>') {
                  emitTagAndPreviousTextNode(); // resets to Data state as well
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else if (quoteRe.test(char)) {
                  // "Parse error" characters that, according to the spec, should be
                  // appended to the attribute name, but we'll treat these characters
                  // as not forming a real HTML tag
                  resetToDataState();
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#after-attribute-name-state
          function stateAfterAttributeName(char) {
              if (whitespaceRe.test(char)) ;
              else if (char === '/') {
                  state = 12 /* SelfClosingStartTag */;
              }
              else if (char === '=') {
                  state = 7 /* BeforeAttributeValue */;
              }
              else if (char === '>') {
                  emitTagAndPreviousTextNode();
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else if (quoteRe.test(char)) {
                  // "Parse error" characters that, according to the spec, should be
                  // appended to the attribute name, but we'll treat these characters
                  // as not forming a real HTML tag
                  resetToDataState();
              }
              else {
                  // Any other character, start a new attribute in the current tag
                  state = 5 /* AttributeName */;
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#before-attribute-value-state
          function stateBeforeAttributeValue(char) {
              if (whitespaceRe.test(char)) ;
              else if (char === "\"") {
                  state = 8 /* AttributeValueDoubleQuoted */;
              }
              else if (char === "'") {
                  state = 9 /* AttributeValueSingleQuoted */;
              }
              else if (/[>=`]/.test(char)) {
                  // Invalid chars after an '=' for an attribute value, don't count
                  // the current tag as an HTML tag
                  resetToDataState();
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else {
                  // Any other character, consider it an unquoted attribute value
                  state = 10 /* AttributeValueUnquoted */;
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#attribute-value-double-quoted-state
          function stateAttributeValueDoubleQuoted(char) {
              if (char === "\"") { // end the current double-quoted attribute
                  state = 11 /* AfterAttributeValueQuoted */;
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#attribute-value-single-quoted-state
          function stateAttributeValueSingleQuoted(char) {
              if (char === "'") { // end the current single-quoted attribute
                  state = 11 /* AfterAttributeValueQuoted */;
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#attribute-value-unquoted-state
          function stateAttributeValueUnquoted(char) {
              if (whitespaceRe.test(char)) {
                  state = 4 /* BeforeAttributeName */;
              }
              else if (char === '>') {
                  emitTagAndPreviousTextNode();
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#after-attribute-value-quoted-state
          function stateAfterAttributeValueQuoted(char) {
              if (whitespaceRe.test(char)) {
                  state = 4 /* BeforeAttributeName */;
              }
              else if (char === '/') {
                  state = 12 /* SelfClosingStartTag */;
              }
              else if (char === '>') {
                  emitTagAndPreviousTextNode();
              }
              else if (char === '<') {
                  // start of another tag (ignore the previous, incomplete one)
                  startNewTag();
              }
              else {
                  // Any other character, "parse error". Spec says to switch to the
                  // BeforeAttributeState and re-consume the character, as it may be
                  // the start of a new attribute name
                  state = 4 /* BeforeAttributeName */;
                  reconsumeCurrentCharacter();
              }
          }
          // A '/' has just been read in the current tag (presumably for '/>'), and
          // this handles the next character
          // https://www.w3.org/TR/html51/syntax.html#self-closing-start-tag-state
          function stateSelfClosingStartTag(char) {
              if (char === '>') {
                  currentTag = new CurrentTag(__assign({}, currentTag, { isClosing: true }));
                  emitTagAndPreviousTextNode(); // resets to Data state as well
              }
              else {
                  state = 4 /* BeforeAttributeName */;
              }
          }
          // https://www.w3.org/TR/html51/syntax.html#markup-declaration-open-state
          // (HTML Comments or !DOCTYPE)
          function stateMarkupDeclarationOpen(char) {
              if (html.substr(charIdx, 2) === '--') { // html comment
                  charIdx += 2; // "consume" characters
                  currentTag = new CurrentTag(__assign({}, currentTag, { type: 'comment' }));
                  state = 14 /* CommentStart */;
              }
              else if (html.substr(charIdx, 7).toUpperCase() === 'DOCTYPE') {
                  charIdx += 7; // "consume" characters
                  currentTag = new CurrentTag(__assign({}, currentTag, { type: 'doctype' }));
                  state = 20 /* Doctype */;
              }
              else {
                  // At this point, the spec specifies that the state machine should
                  // enter the "bogus comment" state, in which case any character(s)
                  // after the '<!' that were read should become an HTML comment up
                  // until the first '>' that is read (or EOF). Instead, we'll assume
                  // that a user just typed '<!' as part of text data
                  resetToDataState();
              }
          }
          // Handles after the sequence '<!--' has been read
          // https://www.w3.org/TR/html51/syntax.html#comment-start-state
          function stateCommentStart(char) {
              if (char === '-') {
                  // We've read the sequence '<!---' at this point (3 dashes)
                  state = 15 /* CommentStartDash */;
              }
              else if (char === '>') {
                  // At this point, we'll assume the comment wasn't a real comment
                  // so we'll just emit it as data. We basically read the sequence
                  // '<!-->'
                  resetToDataState();
              }
              else {
                  // Any other char, take it as part of the comment
                  state = 16 /* Comment */;
              }
          }
          // We've read the sequence '<!---' at this point (3 dashes)
          // https://www.w3.org/TR/html51/syntax.html#comment-start-dash-state
          function stateCommentStartDash(char) {
              if (char === '-') {
                  // We've read '<!----' (4 dashes) at this point
                  state = 18 /* CommentEnd */;
              }
              else if (char === '>') {
                  // At this point, we'll assume the comment wasn't a real comment
                  // so we'll just emit it as data. We basically read the sequence
                  // '<!--->'
                  resetToDataState();
              }
              else {
                  // Anything else, take it as a valid comment
                  state = 16 /* Comment */;
              }
          }
          // Currently reading the comment's text (data)
          // https://www.w3.org/TR/html51/syntax.html#comment-state
          function stateComment(char) {
              if (char === '-') {
                  state = 17 /* CommentEndDash */;
              }
          }
          // When we we've read the first dash inside a comment, it may signal the
          // end of the comment if we read another dash
          // https://www.w3.org/TR/html51/syntax.html#comment-end-dash-state
          function stateCommentEndDash(char) {
              if (char === '-') {
                  state = 18 /* CommentEnd */;
              }
              else {
                  // Wasn't a dash, must still be part of the comment
                  state = 16 /* Comment */;
              }
          }
          // After we've read two dashes inside a comment, it may signal the end of
          // the comment if we then read a '>' char
          // https://www.w3.org/TR/html51/syntax.html#comment-end-state
          function stateCommentEnd(char) {
              if (char === '>') {
                  emitTagAndPreviousTextNode();
              }
              else if (char === '!') {
                  state = 19 /* CommentEndBang */;
              }
              else if (char === '-') ;
              else {
                  // Anything else, switch back to the comment state since we didn't
                  // read the full "end comment" sequence (i.e. '-->')
                  state = 16 /* Comment */;
              }
          }
          // We've read the sequence '--!' inside of a comment
          // https://www.w3.org/TR/html51/syntax.html#comment-end-bang-state
          function stateCommentEndBang(char) {
              if (char === '-') {
                  // We read the sequence '--!-' inside of a comment. The last dash
                  // could signify that the comment is going to close
                  state = 17 /* CommentEndDash */;
              }
              else if (char === '>') {
                  // End of comment with the sequence '--!>'
                  emitTagAndPreviousTextNode();
              }
              else {
                  // The '--!' was not followed by a '>', continue reading the
                  // comment's text
                  state = 16 /* Comment */;
              }
          }
          /**
           * For DOCTYPES in particular, we don't care about the attributes. Just
           * advance to the '>' character and emit the tag, unless we find a '<'
           * character in which case we'll start a new tag.
           *
           * Example doctype tag:
           *    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
           *
           * Actual spec: https://www.w3.org/TR/html51/syntax.html#doctype-state
           */
          function stateDoctype(char) {
              if (char === '>') {
                  emitTagAndPreviousTextNode();
              }
              else if (char === '<') {
                  startNewTag();
              }
          }
          /**
           * Resets the state back to the Data state, and removes the current tag.
           *
           * We'll generally run this function whenever a "parse error" is
           * encountered, where the current tag that is being read no longer looks
           * like a real HTML tag.
           */
          function resetToDataState() {
              state = 0 /* Data */;
              currentTag = noCurrentTag;
          }
          /**
           * Starts a new HTML tag at the current index, ignoring any previous HTML
           * tag that was being read.
           *
           * We'll generally run this function whenever we read a new '<' character,
           * including when we read a '<' character inside of an HTML tag that we were
           * previously reading.
           */
          function startNewTag() {
              state = 1 /* TagOpen */;
              currentTag = new CurrentTag({ idx: charIdx });
          }
          /**
           * Once we've decided to emit an open tag, that means we can also emit the
           * text node before it.
           */
          function emitTagAndPreviousTextNode() {
              var textBeforeTag = html.slice(currentDataIdx, currentTag.idx);
              if (textBeforeTag) {
                  // the html tag was the first element in the html string, or two
                  // tags next to each other, in which case we should not emit a text
                  // node
                  onText(textBeforeTag, currentDataIdx);
              }
              if (currentTag.type === 'comment') {
                  onComment(currentTag.idx);
              }
              else if (currentTag.type === 'doctype') {
                  onDoctype(currentTag.idx);
              }
              else {
                  if (currentTag.isOpening) {
                      onOpenTag(currentTag.name, currentTag.idx);
                  }
                  if (currentTag.isClosing) { // note: self-closing tags will emit both opening and closing
                      onCloseTag(currentTag.name, currentTag.idx);
                  }
              }
              // Since we just emitted a tag, reset to the data state for the next char
              resetToDataState();
              currentDataIdx = charIdx + 1;
          }
          function emitText() {
              var text = html.slice(currentDataIdx, charIdx);
              onText(text, currentDataIdx);
              currentDataIdx = charIdx + 1;
          }
          /**
           * Captures the tag name from the start of the tag to the current character
           * index, and converts it to lower case
           */
          function captureTagName() {
              var startIdx = currentTag.idx + (currentTag.isClosing ? 2 : 1);
              return html.slice(startIdx, charIdx).toLowerCase();
          }
          /**
           * Causes the main loop to re-consume the current character, such as after
           * encountering a "parse error" that changed state and needs to reconsume
           * the same character in that new state.
           */
          function reconsumeCurrentCharacter() {
              charIdx--;
          }
      }
      var CurrentTag = /** @class */ (function () {
          function CurrentTag(cfg) {
              if (cfg === void 0) { cfg = {}; }
              this.idx = cfg.idx !== undefined ? cfg.idx : -1;
              this.type = cfg.type || 'tag';
              this.name = cfg.name || '';
              this.isOpening = !!cfg.isOpening;
              this.isClosing = !!cfg.isClosing;
          }
          return CurrentTag;
      }());

      /**
       * @class Autolinker
       * @extends Object
       *
       * Utility class used to process a given string of text, and wrap the matches in
       * the appropriate anchor (&lt;a&gt;) tags to turn them into links.
       *
       * Any of the configuration options may be provided in an Object provided
       * to the Autolinker constructor, which will configure how the {@link #link link()}
       * method will process the links.
       *
       * For example:
       *
       *     var autolinker = new Autolinker( {
       *         newWindow : false,
       *         truncate  : 30
       *     } );
       *
       *     var html = autolinker.link( "Joe went to www.yahoo.com" );
       *     // produces: 'Joe went to <a href="http://www.yahoo.com">yahoo.com</a>'
       *
       *
       * The {@link #static-link static link()} method may also be used to inline
       * options into a single call, which may be more convenient for one-off uses.
       * For example:
       *
       *     var html = Autolinker.link( "Joe went to www.yahoo.com", {
       *         newWindow : false,
       *         truncate  : 30
       *     } );
       *     // produces: 'Joe went to <a href="http://www.yahoo.com">yahoo.com</a>'
       *
       *
       * ## Custom Replacements of Links
       *
       * If the configuration options do not provide enough flexibility, a {@link #replaceFn}
       * may be provided to fully customize the output of Autolinker. This function is
       * called once for each URL/Email/Phone#/Hashtag/Mention (Twitter, Instagram, Soundcloud)
       * match that is encountered.
       *
       * For example:
       *
       *     var input = "...";  // string with URLs, Email Addresses, Phone #s, Hashtags, and Mentions (Twitter, Instagram, Soundcloud)
       *
       *     var linkedText = Autolinker.link( input, {
       *         replaceFn : function( match ) {
       *             console.log( "href = ", match.getAnchorHref() );
       *             console.log( "text = ", match.getAnchorText() );
       *
       *             switch( match.getType() ) {
       *                 case 'url' :
       *                     console.log( "url: ", match.getUrl() );
       *
       *                     if( match.getUrl().indexOf( 'mysite.com' ) === -1 ) {
       *                         var tag = match.buildTag();  // returns an `Autolinker.HtmlTag` instance, which provides mutator methods for easy changes
       *                         tag.setAttr( 'rel', 'nofollow' );
       *                         tag.addClass( 'external-link' );
       *
       *                         return tag;
       *
       *                     } else {
       *                         return true;  // let Autolinker perform its normal anchor tag replacement
       *                     }
       *
       *                 case 'email' :
       *                     var email = match.getEmail();
       *                     console.log( "email: ", email );
       *
       *                     if( email === "my@own.address" ) {
       *                         return false;  // don't auto-link this particular email address; leave as-is
       *                     } else {
       *                         return;  // no return value will have Autolinker perform its normal anchor tag replacement (same as returning `true`)
       *                     }
       *
       *                 case 'phone' :
       *                     var phoneNumber = match.getPhoneNumber();
       *                     console.log( phoneNumber );
       *
       *                     return '<a href="http://newplace.to.link.phone.numbers.to/">' + phoneNumber + '</a>';
       *
       *                 case 'hashtag' :
       *                     var hashtag = match.getHashtag();
       *                     console.log( hashtag );
       *
       *                     return '<a href="http://newplace.to.link.hashtag.handles.to/">' + hashtag + '</a>';
       *
       *                 case 'mention' :
       *                     var mention = match.getMention();
       *                     console.log( mention );
       *
       *                     return '<a href="http://newplace.to.link.mention.to/">' + mention + '</a>';
       *             }
       *         }
       *     } );
       *
       *
       * The function may return the following values:
       *
       * - `true` (Boolean): Allow Autolinker to replace the match as it normally
       *   would.
       * - `false` (Boolean): Do not replace the current match at all - leave as-is.
       * - Any String: If a string is returned from the function, the string will be
       *   used directly as the replacement HTML for the match.
       * - An {@link Autolinker.HtmlTag} instance, which can be used to build/modify
       *   an HTML tag before writing out its HTML text.
       */
      var Autolinker = /** @class */ (function () {
          /**
           * @method constructor
           * @param {Object} [cfg] The configuration options for the Autolinker instance,
           *   specified in an Object (map).
           */
          function Autolinker(cfg) {
              if (cfg === void 0) { cfg = {}; }
              /**
               * The Autolinker version number exposed on the instance itself.
               *
               * Ex: 0.25.1
               */
              this.version = Autolinker.version;
              /**
               * @cfg {Boolean/Object} [urls]
               *
               * `true` if URLs should be automatically linked, `false` if they should not
               * be. Defaults to `true`.
               *
               * Examples:
               *
               *     urls: true
               *
               *     // or
               *
               *     urls: {
               *         schemeMatches : true,
               *         wwwMatches    : true,
               *         tldMatches    : true
               *     }
               *
               * As shown above, this option also accepts an Object form with 3 properties
               * to allow for more customization of what exactly gets linked. All default
               * to `true`:
               *
               * @cfg {Boolean} [urls.schemeMatches] `true` to match URLs found prefixed
               *   with a scheme, i.e. `http://google.com`, or `other+scheme://google.com`,
               *   `false` to prevent these types of matches.
               * @cfg {Boolean} [urls.wwwMatches] `true` to match urls found prefixed with
               *   `'www.'`, i.e. `www.google.com`. `false` to prevent these types of
               *   matches. Note that if the URL had a prefixed scheme, and
               *   `schemeMatches` is true, it will still be linked.
               * @cfg {Boolean} [urls.tldMatches] `true` to match URLs with known top
               *   level domains (.com, .net, etc.) that are not prefixed with a scheme or
               *   `'www.'`. This option attempts to match anything that looks like a URL
               *   in the given text. Ex: `google.com`, `asdf.org/?page=1`, etc. `false`
               *   to prevent these types of matches.
               */
              this.urls = {}; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} [email=true]
               *
               * `true` if email addresses should be automatically linked, `false` if they
               * should not be.
               */
              this.email = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} [phone=true]
               *
               * `true` if Phone numbers ("(555)555-5555") should be automatically linked,
               * `false` if they should not be.
               */
              this.phone = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean/String} [hashtag=false]
               *
               * A string for the service name to have hashtags (ex: "#myHashtag")
               * auto-linked to. The currently-supported values are:
               *
               * - 'twitter'
               * - 'facebook'
               * - 'instagram'
               *
               * Pass `false` to skip auto-linking of hashtags.
               */
              this.hashtag = false; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {String/Boolean} [mention=false]
               *
               * A string for the service name to have mentions (ex: "@myuser")
               * auto-linked to. The currently supported values are:
               *
               * - 'twitter'
               * - 'instagram'
               * - 'soundcloud'
               *
               * Defaults to `false` to skip auto-linking of mentions.
               */
              this.mention = false; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} [newWindow=true]
               *
               * `true` if the links should open in a new window, `false` otherwise.
               */
              this.newWindow = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean/Object} [stripPrefix=true]
               *
               * `true` if 'http://' (or 'https://') and/or the 'www.' should be stripped
               * from the beginning of URL links' text, `false` otherwise. Defaults to
               * `true`.
               *
               * Examples:
               *
               *     stripPrefix: true
               *
               *     // or
               *
               *     stripPrefix: {
               *         scheme : true,
               *         www    : true
               *     }
               *
               * As shown above, this option also accepts an Object form with 2 properties
               * to allow for more customization of what exactly is prevented from being
               * displayed. Both default to `true`:
               *
               * @cfg {Boolean} [stripPrefix.scheme] `true` to prevent the scheme part of
               *   a URL match from being displayed to the user. Example:
               *   `'http://google.com'` will be displayed as `'google.com'`. `false` to
               *   not strip the scheme. NOTE: Only an `'http://'` or `'https://'` scheme
               *   will be removed, so as not to remove a potentially dangerous scheme
               *   (such as `'file://'` or `'javascript:'`)
               * @cfg {Boolean} [stripPrefix.www] www (Boolean): `true` to prevent the
               *   `'www.'` part of a URL match from being displayed to the user. Ex:
               *   `'www.google.com'` will be displayed as `'google.com'`. `false` to not
               *   strip the `'www'`.
               */
              this.stripPrefix = { scheme: true, www: true }; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} [stripTrailingSlash=true]
               *
               * `true` to remove the trailing slash from URL matches, `false` to keep
               *  the trailing slash.
               *
               *  Example when `true`: `http://google.com/` will be displayed as
               *  `http://google.com`.
               */
              this.stripTrailingSlash = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Boolean} [decodePercentEncoding=true]
               *
               * `true` to decode percent-encoded characters in URL matches, `false` to keep
               *  the percent-encoded characters.
               *
               *  Example when `true`: `https://en.wikipedia.org/wiki/San_Jos%C3%A9` will
               *  be displayed as `https://en.wikipedia.org/wiki/San_José`.
               */
              this.decodePercentEncoding = true; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Number/Object} [truncate=0]
               *
               * ## Number Form
               *
               * A number for how many characters matched text should be truncated to
               * inside the text of a link. If the matched text is over this number of
               * characters, it will be truncated to this length by adding a two period
               * ellipsis ('..') to the end of the string.
               *
               * For example: A url like 'http://www.yahoo.com/some/long/path/to/a/file'
               * truncated to 25 characters might look something like this:
               * 'yahoo.com/some/long/pat..'
               *
               * Example Usage:
               *
               *     truncate: 25
               *
               *
               *  Defaults to `0` for "no truncation."
               *
               *
               * ## Object Form
               *
               * An Object may also be provided with two properties: `length` (Number) and
               * `location` (String). `location` may be one of the following: 'end'
               * (default), 'middle', or 'smart'.
               *
               * Example Usage:
               *
               *     truncate: { length: 25, location: 'middle' }
               *
               * @cfg {Number} [truncate.length=0] How many characters to allow before
               *   truncation will occur. Defaults to `0` for "no truncation."
               * @cfg {"end"/"middle"/"smart"} [truncate.location="end"]
               *
               * - 'end' (default): will truncate up to the number of characters, and then
               *   add an ellipsis at the end. Ex: 'yahoo.com/some/long/pat..'
               * - 'middle': will truncate and add the ellipsis in the middle. Ex:
               *   'yahoo.com/s..th/to/a/file'
               * - 'smart': for URLs where the algorithm attempts to strip out unnecessary
               *   parts first (such as the 'www.', then URL scheme, hash, etc.),
               *   attempting to make the URL human-readable before looking for a good
               *   point to insert the ellipsis if it is still too long. Ex:
               *   'yahoo.com/some..to/a/file'. For more details, see
               *   {@link Autolinker.truncate.TruncateSmart}.
               */
              this.truncate = { length: 0, location: 'end' }; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {String} className
               *
               * A CSS class name to add to the generated links. This class will be added
               * to all links, as well as this class plus match suffixes for styling
               * url/email/phone/hashtag/mention links differently.
               *
               * For example, if this config is provided as "myLink", then:
               *
               * - URL links will have the CSS classes: "myLink myLink-url"
               * - Email links will have the CSS classes: "myLink myLink-email", and
               * - Phone links will have the CSS classes: "myLink myLink-phone"
               * - Hashtag links will have the CSS classes: "myLink myLink-hashtag"
               * - Mention links will have the CSS classes: "myLink myLink-mention myLink-[type]"
               *   where [type] is either "instagram", "twitter" or "soundcloud"
               */
              this.className = ''; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Function} replaceFn
               *
               * A function to individually process each match found in the input string.
               *
               * See the class's description for usage.
               *
               * The `replaceFn` can be called with a different context object (`this`
               * reference) using the {@link #context} cfg.
               *
               * This function is called with the following parameter:
               *
               * @cfg {Autolinker.match.Match} replaceFn.match The Match instance which
               *   can be used to retrieve information about the match that the `replaceFn`
               *   is currently processing. See {@link Autolinker.match.Match} subclasses
               *   for details.
               */
              this.replaceFn = null; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @cfg {Object} context
               *
               * The context object (`this` reference) to call the `replaceFn` with.
               *
               * Defaults to this Autolinker instance.
               */
              this.context = undefined; // default value just to get the above doc comment in the ES5 output and documentation generator
              /**
               * @private
               * @property {Autolinker.matcher.Matcher[]} matchers
               *
               * The {@link Autolinker.matcher.Matcher} instances for this Autolinker
               * instance.
               *
               * This is lazily created in {@link #getMatchers}.
               */
              this.matchers = null;
              /**
               * @private
               * @property {Autolinker.AnchorTagBuilder} tagBuilder
               *
               * The AnchorTagBuilder instance used to build match replacement anchor tags.
               * Note: this is lazily instantiated in the {@link #getTagBuilder} method.
               */
              this.tagBuilder = null;
              // Note: when `this.something` is used in the rhs of these assignments,
              //       it refers to the default values set above the constructor
              this.urls = this.normalizeUrlsCfg(cfg.urls);
              this.email = typeof cfg.email === 'boolean' ? cfg.email : this.email;
              this.phone = typeof cfg.phone === 'boolean' ? cfg.phone : this.phone;
              this.hashtag = cfg.hashtag || this.hashtag;
              this.mention = cfg.mention || this.mention;
              this.newWindow = typeof cfg.newWindow === 'boolean' ? cfg.newWindow : this.newWindow;
              this.stripPrefix = this.normalizeStripPrefixCfg(cfg.stripPrefix);
              this.stripTrailingSlash = typeof cfg.stripTrailingSlash === 'boolean' ? cfg.stripTrailingSlash : this.stripTrailingSlash;
              this.decodePercentEncoding = typeof cfg.decodePercentEncoding === 'boolean' ? cfg.decodePercentEncoding : this.decodePercentEncoding;
              // Validate the value of the `mention` cfg
              var mention = this.mention;
              if (mention !== false && mention !== 'twitter' && mention !== 'instagram' && mention !== 'soundcloud') {
                  throw new Error("invalid `mention` cfg - see docs");
              }
              // Validate the value of the `hashtag` cfg
              var hashtag = this.hashtag;
              if (hashtag !== false && hashtag !== 'twitter' && hashtag !== 'facebook' && hashtag !== 'instagram') {
                  throw new Error("invalid `hashtag` cfg - see docs");
              }
              this.truncate = this.normalizeTruncateCfg(cfg.truncate);
              this.className = cfg.className || this.className;
              this.replaceFn = cfg.replaceFn || this.replaceFn;
              this.context = cfg.context || this;
          }
          /**
           * Automatically links URLs, Email addresses, Phone Numbers, Twitter handles,
           * Hashtags, and Mentions found in the given chunk of HTML. Does not link URLs
           * found within HTML tags.
           *
           * For instance, if given the text: `You should go to http://www.yahoo.com`,
           * then the result will be `You should go to &lt;a href="http://www.yahoo.com"&gt;http://www.yahoo.com&lt;/a&gt;`
           *
           * Example:
           *
           *     var linkedText = Autolinker.link( "Go to google.com", { newWindow: false } );
           *     // Produces: "Go to <a href="http://google.com">google.com</a>"
           *
           * @static
           * @param {String} textOrHtml The HTML or text to find matches within (depending
           *   on if the {@link #urls}, {@link #email}, {@link #phone}, {@link #mention},
           *   {@link #hashtag}, and {@link #mention} options are enabled).
           * @param {Object} [options] Any of the configuration options for the Autolinker
           *   class, specified in an Object (map). See the class description for an
           *   example call.
           * @return {String} The HTML text, with matches automatically linked.
           */
          Autolinker.link = function (textOrHtml, options) {
              var autolinker = new Autolinker(options);
              return autolinker.link(textOrHtml);
          };
          /**
           * Parses the input `textOrHtml` looking for URLs, email addresses, phone
           * numbers, username handles, and hashtags (depending on the configuration
           * of the Autolinker instance), and returns an array of {@link Autolinker.match.Match}
           * objects describing those matches (without making any replacements).
           *
           * Note that if parsing multiple pieces of text, it is slightly more efficient
           * to create an Autolinker instance, and use the instance-level {@link #parse}
           * method.
           *
           * Example:
           *
           *     var matches = Autolinker.parse( "Hello google.com, I am asdf@asdf.com", {
           *         urls: true,
           *         email: true
           *     } );
           *
           *     console.log( matches.length );           // 2
           *     console.log( matches[ 0 ].getType() );   // 'url'
           *     console.log( matches[ 0 ].getUrl() );    // 'google.com'
           *     console.log( matches[ 1 ].getType() );   // 'email'
           *     console.log( matches[ 1 ].getEmail() );  // 'asdf@asdf.com'
           *
           * @static
           * @param {String} textOrHtml The HTML or text to find matches within
           *   (depending on if the {@link #urls}, {@link #email}, {@link #phone},
           *   {@link #hashtag}, and {@link #mention} options are enabled).
           * @param {Object} [options] Any of the configuration options for the Autolinker
           *   class, specified in an Object (map). See the class description for an
           *   example call.
           * @return {Autolinker.match.Match[]} The array of Matches found in the
           *   given input `textOrHtml`.
           */
          Autolinker.parse = function (textOrHtml, options) {
              var autolinker = new Autolinker(options);
              return autolinker.parse(textOrHtml);
          };
          /**
           * Normalizes the {@link #urls} config into an Object with 3 properties:
           * `schemeMatches`, `wwwMatches`, and `tldMatches`, all Booleans.
           *
           * See {@link #urls} config for details.
           *
           * @private
           * @param {Boolean/Object} urls
           * @return {Object}
           */
          Autolinker.prototype.normalizeUrlsCfg = function (urls) {
              if (urls == null)
                  urls = true; // default to `true`
              if (typeof urls === 'boolean') {
                  return { schemeMatches: urls, wwwMatches: urls, tldMatches: urls };
              }
              else { // object form
                  return {
                      schemeMatches: typeof urls.schemeMatches === 'boolean' ? urls.schemeMatches : true,
                      wwwMatches: typeof urls.wwwMatches === 'boolean' ? urls.wwwMatches : true,
                      tldMatches: typeof urls.tldMatches === 'boolean' ? urls.tldMatches : true
                  };
              }
          };
          /**
           * Normalizes the {@link #stripPrefix} config into an Object with 2
           * properties: `scheme`, and `www` - both Booleans.
           *
           * See {@link #stripPrefix} config for details.
           *
           * @private
           * @param {Boolean/Object} stripPrefix
           * @return {Object}
           */
          Autolinker.prototype.normalizeStripPrefixCfg = function (stripPrefix) {
              if (stripPrefix == null)
                  stripPrefix = true; // default to `true`
              if (typeof stripPrefix === 'boolean') {
                  return { scheme: stripPrefix, www: stripPrefix };
              }
              else { // object form
                  return {
                      scheme: typeof stripPrefix.scheme === 'boolean' ? stripPrefix.scheme : true,
                      www: typeof stripPrefix.www === 'boolean' ? stripPrefix.www : true
                  };
              }
          };
          /**
           * Normalizes the {@link #truncate} config into an Object with 2 properties:
           * `length` (Number), and `location` (String).
           *
           * See {@link #truncate} config for details.
           *
           * @private
           * @param {Number/Object} truncate
           * @return {Object}
           */
          Autolinker.prototype.normalizeTruncateCfg = function (truncate) {
              if (typeof truncate === 'number') {
                  return { length: truncate, location: 'end' };
              }
              else { // object, or undefined/null
                  return defaults(truncate || {}, {
                      length: Number.POSITIVE_INFINITY,
                      location: 'end'
                  });
              }
          };
          /**
           * Parses the input `textOrHtml` looking for URLs, email addresses, phone
           * numbers, username handles, and hashtags (depending on the configuration
           * of the Autolinker instance), and returns an array of {@link Autolinker.match.Match}
           * objects describing those matches (without making any replacements).
           *
           * This method is used by the {@link #link} method, but can also be used to
           * simply do parsing of the input in order to discover what kinds of links
           * there are and how many.
           *
           * Example usage:
           *
           *     var autolinker = new Autolinker( {
           *         urls: true,
           *         email: true
           *     } );
           *
           *     var matches = autolinker.parse( "Hello google.com, I am asdf@asdf.com" );
           *
           *     console.log( matches.length );           // 2
           *     console.log( matches[ 0 ].getType() );   // 'url'
           *     console.log( matches[ 0 ].getUrl() );    // 'google.com'
           *     console.log( matches[ 1 ].getType() );   // 'email'
           *     console.log( matches[ 1 ].getEmail() );  // 'asdf@asdf.com'
           *
           * @param {String} textOrHtml The HTML or text to find matches within
           *   (depending on if the {@link #urls}, {@link #email}, {@link #phone},
           *   {@link #hashtag}, and {@link #mention} options are enabled).
           * @return {Autolinker.match.Match[]} The array of Matches found in the
           *   given input `textOrHtml`.
           */
          Autolinker.prototype.parse = function (textOrHtml) {
              var _this = this;
              var skipTagNames = ['a', 'style', 'script'], skipTagsStackCount = 0, // used to only Autolink text outside of anchor/script/style tags. We don't want to autolink something that is already linked inside of an <a> tag, for instance
              matches = [];
              // Find all matches within the `textOrHtml` (but not matches that are
              // already nested within <a>, <style> and <script> tags)
              parseHtml(textOrHtml, {
                  onOpenTag: function (tagName) {
                      if (skipTagNames.indexOf(tagName) >= 0) {
                          skipTagsStackCount++;
                      }
                  },
                  onText: function (text, offset) {
                      // Only process text nodes that are not within an <a>, <style> or <script> tag
                      if (skipTagsStackCount === 0) {
                          // "Walk around" common HTML entities. An '&nbsp;' (for example)
                          // could be at the end of a URL, but we don't want to
                          // include the trailing '&' in the URL. See issue #76
                          // TODO: Handle HTML entities separately in parseHtml() and
                          // don't emit them as "text" except for &amp; entities
                          var htmlCharacterEntitiesRegex = /(&nbsp;|&#160;|&lt;|&#60;|&gt;|&#62;|&quot;|&#34;|&#39;)/gi;
                          var textSplit = splitAndCapture(text, htmlCharacterEntitiesRegex);
                          var currentOffset_1 = offset;
                          textSplit.forEach(function (splitText, i) {
                              // even number matches are text, odd numbers are html entities
                              if (i % 2 === 0) {
                                  var textNodeMatches = _this.parseText(splitText, currentOffset_1);
                                  matches.push.apply(matches, textNodeMatches);
                              }
                              currentOffset_1 += splitText.length;
                          });
                      }
                  },
                  onCloseTag: function (tagName) {
                      if (skipTagNames.indexOf(tagName) >= 0) {
                          skipTagsStackCount = Math.max(skipTagsStackCount - 1, 0); // attempt to handle extraneous </a> tags by making sure the stack count never goes below 0
                      }
                  },
                  onComment: function (offset) { },
                  onDoctype: function (offset) { },
              });
              // After we have found all matches, remove subsequent matches that
              // overlap with a previous match. This can happen for instance with URLs,
              // where the url 'google.com/#link' would match '#link' as a hashtag.
              matches = this.compactMatches(matches);
              // And finally, remove matches for match types that have been turned
              // off. We needed to have all match types turned on initially so that
              // things like hashtags could be filtered out if they were really just
              // part of a URL match (for instance, as a named anchor).
              matches = this.removeUnwantedMatches(matches);
              return matches;
          };
          /**
           * After we have found all matches, we need to remove matches that overlap
           * with a previous match. This can happen for instance with URLs, where the
           * url 'google.com/#link' would match '#link' as a hashtag. Because the
           * '#link' part is contained in a larger match that comes before the HashTag
           * match, we'll remove the HashTag match.
           *
           * @private
           * @param {Autolinker.match.Match[]} matches
           * @return {Autolinker.match.Match[]}
           */
          Autolinker.prototype.compactMatches = function (matches) {
              // First, the matches need to be sorted in order of offset
              matches.sort(function (a, b) { return a.getOffset() - b.getOffset(); });
              for (var i = 0; i < matches.length - 1; i++) {
                  var match = matches[i], offset = match.getOffset(), matchedTextLength = match.getMatchedText().length, endIdx = offset + matchedTextLength;
                  if (i + 1 < matches.length) {
                      // Remove subsequent matches that equal offset with current match
                      if (matches[i + 1].getOffset() === offset) {
                          var removeIdx = matches[i + 1].getMatchedText().length > matchedTextLength ? i : i + 1;
                          matches.splice(removeIdx, 1);
                          continue;
                      }
                      // Remove subsequent matches that overlap with the current match
                      if (matches[i + 1].getOffset() < endIdx) {
                          matches.splice(i + 1, 1);
                      }
                  }
              }
              return matches;
          };
          /**
           * Removes matches for matchers that were turned off in the options. For
           * example, if {@link #hashtag hashtags} were not to be matched, we'll
           * remove them from the `matches` array here.
           *
           * Note: we *must* use all Matchers on the input string, and then filter
           * them out later. For example, if the options were `{ url: false, hashtag: true }`,
           * we wouldn't want to match the text '#link' as a HashTag inside of the text
           * 'google.com/#link'. The way the algorithm works is that we match the full
           * URL first (which prevents the accidental HashTag match), and then we'll
           * simply throw away the URL match.
           *
           * @private
           * @param {Autolinker.match.Match[]} matches The array of matches to remove
           *   the unwanted matches from. Note: this array is mutated for the
           *   removals.
           * @return {Autolinker.match.Match[]} The mutated input `matches` array.
           */
          Autolinker.prototype.removeUnwantedMatches = function (matches) {
              if (!this.hashtag)
                  remove(matches, function (match) { return match.getType() === 'hashtag'; });
              if (!this.email)
                  remove(matches, function (match) { return match.getType() === 'email'; });
              if (!this.phone)
                  remove(matches, function (match) { return match.getType() === 'phone'; });
              if (!this.mention)
                  remove(matches, function (match) { return match.getType() === 'mention'; });
              if (!this.urls.schemeMatches) {
                  remove(matches, function (m) { return m.getType() === 'url' && m.getUrlMatchType() === 'scheme'; });
              }
              if (!this.urls.wwwMatches) {
                  remove(matches, function (m) { return m.getType() === 'url' && m.getUrlMatchType() === 'www'; });
              }
              if (!this.urls.tldMatches) {
                  remove(matches, function (m) { return m.getType() === 'url' && m.getUrlMatchType() === 'tld'; });
              }
              return matches;
          };
          /**
           * Parses the input `text` looking for URLs, email addresses, phone
           * numbers, username handles, and hashtags (depending on the configuration
           * of the Autolinker instance), and returns an array of {@link Autolinker.match.Match}
           * objects describing those matches.
           *
           * This method processes a **non-HTML string**, and is used to parse and
           * match within the text nodes of an HTML string. This method is used
           * internally by {@link #parse}.
           *
           * @private
           * @param {String} text The text to find matches within (depending on if the
           *   {@link #urls}, {@link #email}, {@link #phone},
           *   {@link #hashtag}, and {@link #mention} options are enabled). This must be a non-HTML string.
           * @param {Number} [offset=0] The offset of the text node within the
           *   original string. This is used when parsing with the {@link #parse}
           *   method to generate correct offsets within the {@link Autolinker.match.Match}
           *   instances, but may be omitted if calling this method publicly.
           * @return {Autolinker.match.Match[]} The array of Matches found in the
           *   given input `text`.
           */
          Autolinker.prototype.parseText = function (text, offset) {
              if (offset === void 0) { offset = 0; }
              offset = offset || 0;
              var matchers = this.getMatchers(), matches = [];
              for (var i = 0, numMatchers = matchers.length; i < numMatchers; i++) {
                  var textMatches = matchers[i].parseMatches(text);
                  // Correct the offset of each of the matches. They are originally
                  // the offset of the match within the provided text node, but we
                  // need to correct them to be relative to the original HTML input
                  // string (i.e. the one provided to #parse).
                  for (var j = 0, numTextMatches = textMatches.length; j < numTextMatches; j++) {
                      textMatches[j].setOffset(offset + textMatches[j].getOffset());
                  }
                  matches.push.apply(matches, textMatches);
              }
              return matches;
          };
          /**
           * Automatically links URLs, Email addresses, Phone numbers, Hashtags,
           * and Mentions (Twitter, Instagram, Soundcloud) found in the given chunk of HTML. Does not link
           * URLs found within HTML tags.
           *
           * For instance, if given the text: `You should go to http://www.yahoo.com`,
           * then the result will be `You should go to
           * &lt;a href="http://www.yahoo.com"&gt;http://www.yahoo.com&lt;/a&gt;`
           *
           * This method finds the text around any HTML elements in the input
           * `textOrHtml`, which will be the text that is processed. Any original HTML
           * elements will be left as-is, as well as the text that is already wrapped
           * in anchor (&lt;a&gt;) tags.
           *
           * @param {String} textOrHtml The HTML or text to autolink matches within
           *   (depending on if the {@link #urls}, {@link #email}, {@link #phone}, {@link #hashtag}, and {@link #mention} options are enabled).
           * @return {String} The HTML, with matches automatically linked.
           */
          Autolinker.prototype.link = function (textOrHtml) {
              if (!textOrHtml) {
                  return "";
              } // handle `null` and `undefined`
              var matches = this.parse(textOrHtml), newHtml = [], lastIndex = 0;
              for (var i = 0, len = matches.length; i < len; i++) {
                  var match = matches[i];
                  newHtml.push(textOrHtml.substring(lastIndex, match.getOffset()));
                  newHtml.push(this.createMatchReturnVal(match));
                  lastIndex = match.getOffset() + match.getMatchedText().length;
              }
              newHtml.push(textOrHtml.substring(lastIndex)); // handle the text after the last match
              return newHtml.join('');
          };
          /**
           * Creates the return string value for a given match in the input string.
           *
           * This method handles the {@link #replaceFn}, if one was provided.
           *
           * @private
           * @param {Autolinker.match.Match} match The Match object that represents
           *   the match.
           * @return {String} The string that the `match` should be replaced with.
           *   This is usually the anchor tag string, but may be the `matchStr` itself
           *   if the match is not to be replaced.
           */
          Autolinker.prototype.createMatchReturnVal = function (match) {
              // Handle a custom `replaceFn` being provided
              var replaceFnResult;
              if (this.replaceFn) {
                  replaceFnResult = this.replaceFn.call(this.context, match); // Autolinker instance is the context
              }
              if (typeof replaceFnResult === 'string') {
                  return replaceFnResult; // `replaceFn` returned a string, use that
              }
              else if (replaceFnResult === false) {
                  return match.getMatchedText(); // no replacement for the match
              }
              else if (replaceFnResult instanceof HtmlTag) {
                  return replaceFnResult.toAnchorString();
              }
              else { // replaceFnResult === true, or no/unknown return value from function
                  // Perform Autolinker's default anchor tag generation
                  var anchorTag = match.buildTag(); // returns an Autolinker.HtmlTag instance
                  return anchorTag.toAnchorString();
              }
          };
          /**
           * Lazily instantiates and returns the {@link Autolinker.matcher.Matcher}
           * instances for this Autolinker instance.
           *
           * @private
           * @return {Autolinker.matcher.Matcher[]}
           */
          Autolinker.prototype.getMatchers = function () {
              if (!this.matchers) {
                  var tagBuilder = this.getTagBuilder();
                  var matchers = [
                      new HashtagMatcher({ tagBuilder: tagBuilder, serviceName: this.hashtag }),
                      new EmailMatcher({ tagBuilder: tagBuilder }),
                      new PhoneMatcher({ tagBuilder: tagBuilder }),
                      new MentionMatcher({ tagBuilder: tagBuilder, serviceName: this.mention }),
                      new UrlMatcher({ tagBuilder: tagBuilder, stripPrefix: this.stripPrefix, stripTrailingSlash: this.stripTrailingSlash, decodePercentEncoding: this.decodePercentEncoding })
                  ];
                  return (this.matchers = matchers);
              }
              else {
                  return this.matchers;
              }
          };
          /**
           * Returns the {@link #tagBuilder} instance for this Autolinker instance,
           * lazily instantiating it if it does not yet exist.
           *
           * @private
           * @return {Autolinker.AnchorTagBuilder}
           */
          Autolinker.prototype.getTagBuilder = function () {
              var tagBuilder = this.tagBuilder;
              if (!tagBuilder) {
                  tagBuilder = this.tagBuilder = new AnchorTagBuilder({
                      newWindow: this.newWindow,
                      truncate: this.truncate,
                      className: this.className
                  });
              }
              return tagBuilder;
          };
          /**
           * @static
           * @property {String} version
           *
           * The Autolinker version number in the form major.minor.patch
           *
           * Ex: 0.25.1
           */
          Autolinker.version = '3.11.0';
          /**
           * For backwards compatibility with Autolinker 1.x, the AnchorTagBuilder
           * class is provided as a static on the Autolinker class.
           */
          Autolinker.AnchorTagBuilder = AnchorTagBuilder;
          /**
           * For backwards compatibility with Autolinker 1.x, the HtmlTag class is
           * provided as a static on the Autolinker class.
           */
          Autolinker.HtmlTag = HtmlTag;
          /**
           * For backwards compatibility with Autolinker 1.x, the Matcher classes are
           * provided as statics on the Autolinker class.
           */
          Autolinker.matcher = {
              Email: EmailMatcher,
              Hashtag: HashtagMatcher,
              Matcher: Matcher,
              Mention: MentionMatcher,
              Phone: PhoneMatcher,
              Url: UrlMatcher
          };
          /**
           * For backwards compatibility with Autolinker 1.x, the Match classes are
           * provided as statics on the Autolinker class.
           */
          Autolinker.match = {
              Email: EmailMatch,
              Hashtag: HashtagMatch,
              Match: Match,
              Mention: MentionMatch,
              Phone: PhoneMatch,
              Url: UrlMatch
          };
          return Autolinker;
      }());

      return Autolinker;

  }));




  var Autolinker = tmp$4.Autolinker;

  /**
  @license
   Copyright (c) 2013 Gildas Lormeau. All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in
   the documentation and/or other materials provided with the distribution.

   3. The names of the authors may not be used to endorse or promote products
   derived from this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
   INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
   INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
   INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
   OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
   EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  **/

  var tmp$5 = {};

  (function(obj) {

  	var ERR_BAD_FORMAT = "File format is not recognized.";
  	var ERR_ENCRYPTED = "File contains encrypted entry.";
  	var ERR_ZIP64 = "File is using Zip64 (4gb+ file size).";
  	var ERR_READ = "Error while reading zip file.";
  	var ERR_WRITE = "Error while writing zip file.";
  	var ERR_WRITE_DATA = "Error while writing file data.";
  	var ERR_READ_DATA = "Error while reading file data.";
  	var ERR_DUPLICATED_NAME = "File already exists.";
  	var CHUNK_SIZE = 512 * 1024;

  	var INFLATE_JS = "inflate.js";
  	var DEFLATE_JS = "deflate.js";

  	var TEXT_PLAIN = "text/plain";

  	var MESSAGE_EVENT = "message";

  	var appendABViewSupported;
  	try {
  		appendABViewSupported = new Blob([ new DataView(new ArrayBuffer(0)) ]).size === 0;
  	} catch (e) {
  	}

  	function Crc32() {
  		var crc = -1, that = this;
  		that.append = function(data) {
  			var offset, table = that.table;
  			for (offset = 0; offset < data.length; offset++)
  				crc = (crc >>> 8) ^ table[(crc ^ data[offset]) & 0xFF];
  		};
  		that.get = function() {
  			return ~crc;
  		};
  	}
  	Crc32.prototype.table = (function() {
  		var i, j, t, table = [];
  		for (i = 0; i < 256; i++) {
  			t = i;
  			for (j = 0; j < 8; j++)
  				if (t & 1)
  					t = (t >>> 1) ^ 0xEDB88320;
  				else
  					t = t >>> 1;
  			table[i] = t;
  		}
  		return table;
  	})();

  	function blobSlice(blob, index, length) {
  		if (blob.slice)
  			return blob.slice(index, index + length);
  		else if (blob.webkitSlice)
  			return blob.webkitSlice(index, index + length);
  		else if (blob.mozSlice)
  			return blob.mozSlice(index, index + length);
  		else if (blob.msSlice)
  			return blob.msSlice(index, index + length);
  	}

  	function getDataHelper(byteLength, bytes) {
  		var dataBuffer, dataArray;
  		dataBuffer = new ArrayBuffer(byteLength);
  		dataArray = new Uint8Array(dataBuffer);
  		if (bytes)
  			dataArray.set(bytes, 0);
  		return {
  			buffer : dataBuffer,
  			array : dataArray,
  			view : new DataView(dataBuffer)
  		};
  	}

  	// Readers
  	function Reader() {
  	}

  	function TextReader(text) {
  		var that = this, blobReader;

  		function init(callback, onerror) {
  			var blob = new Blob([ text ], {
  				type : TEXT_PLAIN
  			});
  			blobReader = new BlobReader(blob);
  			blobReader.init(function() {
  				that.size = blobReader.size;
  				callback();
  			}, onerror);
  		}

  		function readUint8Array(index, length, callback, onerror) {
  			blobReader.readUint8Array(index, length, callback, onerror);
  		}

  		that.size = 0;
  		that.init = init;
  		that.readUint8Array = readUint8Array;
  	}
  	TextReader.prototype = new Reader();
  	TextReader.prototype.constructor = TextReader;

  	function Data64URIReader(dataURI) {
  		var that = this, dataStart;

  		function init(callback) {
  			var dataEnd = dataURI.length;
  			while (dataURI.charAt(dataEnd - 1) == "=")
  				dataEnd--;
  			dataStart = dataURI.indexOf(",") + 1;
  			that.size = Math.floor((dataEnd - dataStart) * 0.75);
  			callback();
  		}

  		function readUint8Array(index, length, callback) {
  			var i, data = getDataHelper(length);
  			var start = Math.floor(index / 3) * 4;
  			var end = Math.ceil((index + length) / 3) * 4;
  			var bytes = window.atob(dataURI.substring(start + dataStart, end + dataStart));
  			var delta = index - Math.floor(start / 4) * 3;
  			for (i = delta; i < delta + length; i++)
  				data.array[i - delta] = bytes.charCodeAt(i);
  			callback(data.array);
  		}

  		that.size = 0;
  		that.init = init;
  		that.readUint8Array = readUint8Array;
  	}
  	Data64URIReader.prototype = new Reader();
  	Data64URIReader.prototype.constructor = Data64URIReader;

  	function BlobReader(blob) {
  		var that = this;

  		function init(callback) {
  			this.size = blob.size;
  			callback();
  		}

  		function readUint8Array(index, length, callback, onerror) {
  			var reader = new FileReader();
  			reader.onload = function(e) {
  				callback(new Uint8Array(e.target.result));
  			};
  			reader.onerror = onerror;
  			reader.readAsArrayBuffer(blobSlice(blob, index, length));
  		}

  		that.size = 0;
  		that.init = init;
  		that.readUint8Array = readUint8Array;
  	}
  	BlobReader.prototype = new Reader();
  	BlobReader.prototype.constructor = BlobReader;

  	// Writers

  	function Writer() {
  	}
  	Writer.prototype.getData = function(callback) {
  		callback(this.data);
  	};

  	function TextWriter(encoding) {
  		var that = this, blob;

  		function init(callback) {
  			blob = new Blob([], {
  				type : TEXT_PLAIN
  			});
  			callback();
  		}

  		function writeUint8Array(array, callback) {
  			blob = new Blob([ blob, appendABViewSupported ? array : array.buffer ], {
  				type : TEXT_PLAIN
  			});
  			callback();
  		}

  		function getData(callback, onerror) {
  			var reader = new FileReader();
  			reader.onload = function(e) {
  				callback(e.target.result);
  			};
  			reader.onerror = onerror;
  			reader.readAsText(blob, encoding);
  		}

  		that.init = init;
  		that.writeUint8Array = writeUint8Array;
  		that.getData = getData;
  	}
  	TextWriter.prototype = new Writer();
  	TextWriter.prototype.constructor = TextWriter;

  	function Data64URIWriter(contentType) {
  		var that = this, data = "", pending = "";

  		function init(callback) {
  			data += "data:" + (contentType || "") + ";base64,";
  			callback();
  		}

  		function writeUint8Array(array, callback) {
  			var i, delta = pending.length, dataString = pending;
  			pending = "";
  			for (i = 0; i < (Math.floor((delta + array.length) / 3) * 3) - delta; i++)
  				dataString += String.fromCharCode(array[i]);
  			for (; i < array.length; i++)
  				pending += String.fromCharCode(array[i]);
  			if (dataString.length > 2)
  				data += window.btoa(dataString);
  			else
  				pending = dataString;
  			callback();
  		}

  		function getData(callback) {
  			callback(data + window.btoa(pending));
  		}

  		that.init = init;
  		that.writeUint8Array = writeUint8Array;
  		that.getData = getData;
  	}
  	Data64URIWriter.prototype = new Writer();
  	Data64URIWriter.prototype.constructor = Data64URIWriter;

  	function BlobWriter(contentType) {
  		var blob, that = this;

  		function init(callback) {
  			blob = new Blob([], {
  				type : contentType
  			});
  			callback();
  		}

  		function writeUint8Array(array, callback) {
  			blob = new Blob([ blob, appendABViewSupported ? array : array.buffer ], {
  				type : contentType
  			});
  			callback();
  		}

  		function getData(callback) {
  			callback(blob);
  		}

  		that.init = init;
  		that.writeUint8Array = writeUint8Array;
  		that.getData = getData;
  	}
  	BlobWriter.prototype = new Writer();
  	BlobWriter.prototype.constructor = BlobWriter;

  	// inflate/deflate core functions

  	function launchWorkerProcess(worker, reader, writer, offset, size, onappend, onprogress, onend, onreaderror, onwriteerror) {
  		var chunkIndex = 0, index, outputSize;

  		function onflush() {
  			worker.removeEventListener(MESSAGE_EVENT, onmessage, false);
  			onend(outputSize);
  		}

  		function onmessage(event) {
  			var message = event.data, data = message.data;

  			if (message.onappend) {
  				outputSize += data.length;
  				writer.writeUint8Array(data, function() {
  					onappend(false, data);
  					step();
  				}, onwriteerror);
  			}
  			if (message.onflush)
  				if (data) {
  					outputSize += data.length;
  					writer.writeUint8Array(data, function() {
  						onappend(false, data);
  						onflush();
  					}, onwriteerror);
  				} else
  					onflush();
  			if (message.progress && onprogress)
  				onprogress(index + message.current, size);
  		}

  		function step() {
  			index = chunkIndex * CHUNK_SIZE;
  			if (index < size)
  				reader.readUint8Array(offset + index, Math.min(CHUNK_SIZE, size - index), function(array) {
  					worker.postMessage({
  						append : true,
  						data : array
  					});
  					chunkIndex++;
  					if (onprogress)
  						onprogress(index, size);
  					onappend(true, array);
  				}, onreaderror);
  			else
  				worker.postMessage({
  					flush : true
  				});
  		}

  		outputSize = 0;
  		worker.addEventListener(MESSAGE_EVENT, onmessage, false);
  		step();
  	}

  	function launchProcess(process, reader, writer, offset, size, onappend, onprogress, onend, onreaderror, onwriteerror) {
  		var chunkIndex = 0, index, outputSize = 0;

  		function step() {
  			var outputData;
  			index = chunkIndex * CHUNK_SIZE;
  			if (index < size)
  				reader.readUint8Array(offset + index, Math.min(CHUNK_SIZE, size - index), function(inputData) {
  					var outputData = process.append(inputData, function() {
  						if (onprogress)
  							onprogress(offset + index, size);
  					});
  					outputSize += outputData.length;
  					onappend(true, inputData);
  					writer.writeUint8Array(outputData, function() {
  						onappend(false, outputData);
  						chunkIndex++;
  						setTimeout(step, 1);
  					}, onwriteerror);
  					if (onprogress)
  						onprogress(index, size);
  				}, onreaderror);
  			else {
  				outputData = process.flush();
  				if (outputData) {
  					outputSize += outputData.length;
  					writer.writeUint8Array(outputData, function() {
  						onappend(false, outputData);
  						onend(outputSize);
  					}, onwriteerror);
  				} else
  					onend(outputSize);
  			}
  		}

  		step();
  	}

  	function inflate(reader, writer, offset, size, computeCrc32, onend, onprogress, onreaderror, onwriteerror) {
  		var worker, crc32 = new Crc32();

  		function oninflateappend(sending, array) {
  			if (computeCrc32 && !sending)
  				crc32.append(array);
  		}

  		function oninflateend(outputSize) {
  			onend(outputSize, crc32.get());
  		}

  		if (obj.zip.useWebWorkers) {
  			worker = new Worker(obj.zip.workerScriptsPath + INFLATE_JS);
  			launchWorkerProcess(worker, reader, writer, offset, size, oninflateappend, onprogress, oninflateend, onreaderror, onwriteerror);
  		} else
  			launchProcess(new obj.zip.Inflater(), reader, writer, offset, size, oninflateappend, onprogress, oninflateend, onreaderror, onwriteerror);
  		return worker;
  	}

  	function deflate(reader, writer, level, onend, onprogress, onreaderror, onwriteerror) {
  		var worker, crc32 = new Crc32();

  		function ondeflateappend(sending, array) {
  			if (sending)
  				crc32.append(array);
  		}

  		function ondeflateend(outputSize) {
  			onend(outputSize, crc32.get());
  		}

  		function onmessage() {
  			worker.removeEventListener(MESSAGE_EVENT, onmessage, false);
  			launchWorkerProcess(worker, reader, writer, 0, reader.size, ondeflateappend, onprogress, ondeflateend, onreaderror, onwriteerror);
  		}

  		if (obj.zip.useWebWorkers) {
  			worker = new Worker(obj.zip.workerScriptsPath + DEFLATE_JS);
  			worker.addEventListener(MESSAGE_EVENT, onmessage, false);
  			worker.postMessage({
  				init : true,
  				level : level
  			});
  		} else
  			launchProcess(new obj.zip.Deflater(), reader, writer, 0, reader.size, ondeflateappend, onprogress, ondeflateend, onreaderror, onwriteerror);
  		return worker;
  	}

  	function copy(reader, writer, offset, size, computeCrc32, onend, onprogress, onreaderror, onwriteerror) {
  		var chunkIndex = 0, crc32 = new Crc32();

  		function step() {
  			var index = chunkIndex * CHUNK_SIZE;
  			if (index < size)
  				reader.readUint8Array(offset + index, Math.min(CHUNK_SIZE, size - index), function(array) {
  					if (computeCrc32)
  						crc32.append(array);
  					if (onprogress)
  						onprogress(index, size, array);
  					writer.writeUint8Array(array, function() {
  						chunkIndex++;
  						step();
  					}, onwriteerror);
  				}, onreaderror);
  			else
  				onend(size, crc32.get());
  		}

  		step();
  	}

  	// ZipReader

  	function decodeASCII(str) {
  		var i, out = "", charCode, extendedASCII = [ '\u00C7', '\u00FC', '\u00E9', '\u00E2', '\u00E4', '\u00E0', '\u00E5', '\u00E7', '\u00EA', '\u00EB',
  				'\u00E8', '\u00EF', '\u00EE', '\u00EC', '\u00C4', '\u00C5', '\u00C9', '\u00E6', '\u00C6', '\u00F4', '\u00F6', '\u00F2', '\u00FB', '\u00F9',
  				'\u00FF', '\u00D6', '\u00DC', '\u00F8', '\u00A3', '\u00D8', '\u00D7', '\u0192', '\u00E1', '\u00ED', '\u00F3', '\u00FA', '\u00F1', '\u00D1',
  				'\u00AA', '\u00BA', '\u00BF', '\u00AE', '\u00AC', '\u00BD', '\u00BC', '\u00A1', '\u00AB', '\u00BB', '_', '_', '_', '\u00A6', '\u00A6',
  				'\u00C1', '\u00C2', '\u00C0', '\u00A9', '\u00A6', '\u00A6', '+', '+', '\u00A2', '\u00A5', '+', '+', '-', '-', '+', '-', '+', '\u00E3',
  				'\u00C3', '+', '+', '-', '-', '\u00A6', '-', '+', '\u00A4', '\u00F0', '\u00D0', '\u00CA', '\u00CB', '\u00C8', 'i', '\u00CD', '\u00CE',
  				'\u00CF', '+', '+', '_', '_', '\u00A6', '\u00CC', '_', '\u00D3', '\u00DF', '\u00D4', '\u00D2', '\u00F5', '\u00D5', '\u00B5', '\u00FE',
  				'\u00DE', '\u00DA', '\u00DB', '\u00D9', '\u00FD', '\u00DD', '\u00AF', '\u00B4', '\u00AD', '\u00B1', '_', '\u00BE', '\u00B6', '\u00A7',
  				'\u00F7', '\u00B8', '\u00B0', '\u00A8', '\u00B7', '\u00B9', '\u00B3', '\u00B2', '_', ' ' ];
  		for (i = 0; i < str.length; i++) {
  			charCode = str.charCodeAt(i) & 0xFF;
  			if (charCode > 127)
  				out += extendedASCII[charCode - 128];
  			else
  				out += String.fromCharCode(charCode);
  		}
  		return out;
  	}

  	function decodeUTF8(string) {
  		return decodeURIComponent(escape(string));
  	}

  	function getString(bytes) {
  		var i, str = "";
  		for (i = 0; i < bytes.length; i++)
  			str += String.fromCharCode(bytes[i]);
  		return str;
  	}

  	function getDate(timeRaw) {
  		var date = (timeRaw & 0xffff0000) >> 16, time = timeRaw & 0x0000ffff;
  		try {
  			return new Date(1980 + ((date & 0xFE00) >> 9), ((date & 0x01E0) >> 5) - 1, date & 0x001F, (time & 0xF800) >> 11, (time & 0x07E0) >> 5,
  					(time & 0x001F) * 2, 0);
  		} catch (e) {
  		}
  	}

  	function readCommonHeader(entry, data, index, centralDirectory, onerror) {
  		entry.version = data.view.getUint16(index, true);
  		entry.bitFlag = data.view.getUint16(index + 2, true);
  		entry.compressionMethod = data.view.getUint16(index + 4, true);
  		entry.lastModDateRaw = data.view.getUint32(index + 6, true);
  		entry.lastModDate = getDate(entry.lastModDateRaw);
  		if ((entry.bitFlag & 0x01) === 0x01) {
  			onerror(ERR_ENCRYPTED);
  			return;
  		}
  		if (centralDirectory || (entry.bitFlag & 0x0008) != 0x0008) {
  			entry.crc32 = data.view.getUint32(index + 10, true);
  			entry.compressedSize = data.view.getUint32(index + 14, true);
  			entry.uncompressedSize = data.view.getUint32(index + 18, true);
  		}
  		if (entry.compressedSize === 0xFFFFFFFF || entry.uncompressedSize === 0xFFFFFFFF) {
  			onerror(ERR_ZIP64);
  			return;
  		}
  		entry.filenameLength = data.view.getUint16(index + 22, true);
  		entry.extraFieldLength = data.view.getUint16(index + 24, true);
  	}

  	function createZipReader(reader, onerror) {
  		function Entry() {
  		}

  		Entry.prototype.getData = function(writer, onend, onprogress, checkCrc32) {
  			var that = this, worker;

  			function terminate(callback, param) {
  				if (worker)
  					worker.terminate();
  				worker = null;
  				if (callback)
  					callback(param);
  			}

  			function testCrc32(crc32) {
  				var dataCrc32 = getDataHelper(4);
  				dataCrc32.view.setUint32(0, crc32);
  				return that.crc32 == dataCrc32.view.getUint32(0);
  			}

  			function getWriterData(uncompressedSize, crc32) {
  				if (checkCrc32 && !testCrc32(crc32))
  					onreaderror();
  				else
  					writer.getData(function(data) {
  						terminate(onend, data);
  					});
  			}

  			function onreaderror() {
  				terminate(onerror, ERR_READ_DATA);
  			}

  			function onwriteerror() {
  				terminate(onerror, ERR_WRITE_DATA);
  			}

  			reader.readUint8Array(that.offset, 30, function(bytes) {
  				var data = getDataHelper(bytes.length, bytes), dataOffset;
  				if (data.view.getUint32(0) != 0x504b0304) {
  					onerror(ERR_BAD_FORMAT);
  					return;
  				}
  				readCommonHeader(that, data, 4, false, onerror);
  				dataOffset = that.offset + 30 + that.filenameLength + that.extraFieldLength;
  				writer.init(function() {
  					if (that.compressionMethod === 0)
  						copy(reader, writer, dataOffset, that.compressedSize, checkCrc32, getWriterData, onprogress, onreaderror, onwriteerror);
  					else
  						worker = inflate(reader, writer, dataOffset, that.compressedSize, checkCrc32, getWriterData, onprogress, onreaderror, onwriteerror);
  				}, onwriteerror);
  			}, onreaderror);
  		};

  		function seekEOCDR(offset, entriesCallback) {
  			reader.readUint8Array(reader.size - offset, offset, function(bytes) {
  				var dataView = getDataHelper(bytes.length, bytes).view;
  				if (dataView.getUint32(0) != 0x504b0506) {
  					seekEOCDR(offset + 1, entriesCallback);
  				} else {
  					entriesCallback(dataView);
  				}
  			}, function() {
  				onerror(ERR_READ);
  			});
  		}

  		return {
  			getEntries : function(callback) {
  				if (reader.size < 22) {
  					onerror(ERR_BAD_FORMAT);
  					return;
  				}
  				// look for End of central directory record
  				seekEOCDR(22, function(dataView) {
  					var datalength, fileslength;
  					datalength = dataView.getUint32(16, true);
  					fileslength = dataView.getUint16(8, true);
  					reader.readUint8Array(datalength, reader.size - datalength, function(bytes) {
  						var i, index = 0, entries = [], entry, filename, comment, data = getDataHelper(bytes.length, bytes);
  						for (i = 0; i < fileslength; i++) {
  							entry = new Entry();
  							if (data.view.getUint32(index) != 0x504b0102) {
  								onerror(ERR_BAD_FORMAT);
  								return;
  							}
  							readCommonHeader(entry, data, index + 6, true, onerror);
  							entry.commentLength = data.view.getUint16(index + 32, true);
  							entry.directory = ((data.view.getUint8(index + 38) & 0x10) == 0x10);
  							entry.offset = data.view.getUint32(index + 42, true);
  							filename = getString(data.array.subarray(index + 46, index + 46 + entry.filenameLength));
  							entry.filename = ((entry.bitFlag & 0x0800) === 0x0800) ? decodeUTF8(filename) : decodeASCII(filename);
  							if (!entry.directory && entry.filename.charAt(entry.filename.length - 1) == "/")
  								entry.directory = true;
  							comment = getString(data.array.subarray(index + 46 + entry.filenameLength + entry.extraFieldLength, index + 46
  									+ entry.filenameLength + entry.extraFieldLength + entry.commentLength));
  							entry.comment = ((entry.bitFlag & 0x0800) === 0x0800) ? decodeUTF8(comment) : decodeASCII(comment);
  							entries.push(entry);
  							index += 46 + entry.filenameLength + entry.extraFieldLength + entry.commentLength;
  						}
  						callback(entries);
  					}, function() {
  						onerror(ERR_READ);
  					});
  				});
  			},
  			close : function(callback) {
  				if (callback)
  					callback();
  			}
  		};
  	}

  	// ZipWriter

  	function encodeUTF8(string) {
  		return unescape(encodeURIComponent(string));
  	}

  	function getBytes(str) {
  		var i, array = [];
  		for (i = 0; i < str.length; i++)
  			array.push(str.charCodeAt(i));
  		return array;
  	}

  	function createZipWriter(writer, onerror, dontDeflate) {
  		var worker, files = {}, filenames = [], datalength = 0;

  		function terminate(callback, message) {
  			if (worker)
  				worker.terminate();
  			worker = null;
  			if (callback)
  				callback(message);
  		}

  		function onwriteerror() {
  			terminate(onerror, ERR_WRITE);
  		}

  		function onreaderror() {
  			terminate(onerror, ERR_READ_DATA);
  		}

  		return {
  			add : function(name, reader, onend, onprogress, options) {
  				var header, filename, date;

  				function writeHeader(callback) {
  					var data;
  					date = options.lastModDate || new Date();
  					header = getDataHelper(26);
  					files[name] = {
  						headerArray : header.array,
  						directory : options.directory,
  						filename : filename,
  						offset : datalength,
  						comment : getBytes(encodeUTF8(options.comment || ""))
  					};
  					header.view.setUint32(0, 0x14000808);
  					if (options.version)
  						header.view.setUint8(0, options.version);
  					if (!dontDeflate && options.level !== 0 && !options.directory)
  						header.view.setUint16(4, 0x0800);
  					header.view.setUint16(6, (((date.getHours() << 6) | date.getMinutes()) << 5) | date.getSeconds() / 2, true);
  					header.view.setUint16(8, ((((date.getFullYear() - 1980) << 4) | (date.getMonth() + 1)) << 5) | date.getDate(), true);
  					header.view.setUint16(22, filename.length, true);
  					data = getDataHelper(30 + filename.length);
  					data.view.setUint32(0, 0x504b0304);
  					data.array.set(header.array, 4);
  					data.array.set(filename, 30);
  					datalength += data.array.length;
  					writer.writeUint8Array(data.array, callback, onwriteerror);
  				}

  				function writeFooter(compressedLength, crc32) {
  					var footer = getDataHelper(16);
  					datalength += compressedLength || 0;
  					footer.view.setUint32(0, 0x504b0708);
  					if (typeof crc32 != "undefined") {
  						header.view.setUint32(10, crc32, true);
  						footer.view.setUint32(4, crc32, true);
  					}
  					if (reader) {
  						footer.view.setUint32(8, compressedLength, true);
  						header.view.setUint32(14, compressedLength, true);
  						footer.view.setUint32(12, reader.size, true);
  						header.view.setUint32(18, reader.size, true);
  					}
  					writer.writeUint8Array(footer.array, function() {
  						datalength += 16;
  						terminate(onend);
  					}, onwriteerror);
  				}

  				function writeFile() {
  					options = options || {};
  					name = name.trim();
  					if (options.directory && name.charAt(name.length - 1) != "/")
  						name += "/";
  					if (files.hasOwnProperty(name)) {
  						onerror(ERR_DUPLICATED_NAME);
  						return;
  					}
  					filename = getBytes(encodeUTF8(name));
  					filenames.push(name);
  					writeHeader(function() {
  						if (reader)
  							if (dontDeflate || options.level === 0)
  								copy(reader, writer, 0, reader.size, true, writeFooter, onprogress, onreaderror, onwriteerror);
  							else
  								worker = deflate(reader, writer, options.level, writeFooter, onprogress, onreaderror, onwriteerror);
  						else
  							writeFooter();
  					});
  				}

  				if (reader)
  					reader.init(writeFile, onreaderror);
  				else
  					writeFile();
  			},
  			close : function(callback) {
  				var data, length = 0, index = 0, indexFilename, file;
  				for (indexFilename = 0; indexFilename < filenames.length; indexFilename++) {
  					file = files[filenames[indexFilename]];
  					length += 46 + file.filename.length + file.comment.length;
  				}
  				data = getDataHelper(length + 22);
  				for (indexFilename = 0; indexFilename < filenames.length; indexFilename++) {
  					file = files[filenames[indexFilename]];
  					data.view.setUint32(index, 0x504b0102);
  					data.view.setUint16(index + 4, 0x1400);
  					data.array.set(file.headerArray, index + 6);
  					data.view.setUint16(index + 32, file.comment.length, true);
  					if (file.directory)
  						data.view.setUint8(index + 38, 0x10);
  					data.view.setUint32(index + 42, file.offset, true);
  					data.array.set(file.filename, index + 46);
  					data.array.set(file.comment, index + 46 + file.filename.length);
  					index += 46 + file.filename.length + file.comment.length;
  				}
  				data.view.setUint32(index, 0x504b0506);
  				data.view.setUint16(index + 8, filenames.length, true);
  				data.view.setUint16(index + 10, filenames.length, true);
  				data.view.setUint32(index + 12, length, true);
  				data.view.setUint32(index + 16, datalength, true);
  				writer.writeUint8Array(data.array, function() {
  					terminate(function() {
  						writer.getData(callback);
  					});
  				}, onwriteerror);
  			}
  		};
  	}

  	obj.zip = {
  		Reader : Reader,
  		Writer : Writer,
  		BlobReader : BlobReader,
  		Data64URIReader : Data64URIReader,
  		TextReader : TextReader,
  		BlobWriter : BlobWriter,
  		Data64URIWriter : Data64URIWriter,
  		TextWriter : TextWriter,
  		createReader : function(reader, callback, onerror) {
  			reader.init(function() {
  				callback(createZipReader(reader, onerror));
  			}, onerror);
  		},
  		createWriter : function(writer, callback, onerror, dontDeflate) {
  			writer.init(function() {
  				callback(createZipWriter(writer, onerror, dontDeflate));
  			}, onerror);
  		},
  		useWebWorkers : true
  	};

  	var workerScriptsPath;

  	Object.defineProperties(obj.zip, {
          'workerScriptsPath' : {
              get : function() {
                  if (typeof workerScriptsPath === 'undefined') {
                      workerScriptsPath = buildModuleUrl('ThirdParty/Workers/');
                  }
                  return workerScriptsPath;
              }
          }
      });

  })(tmp$5);

      var zip = tmp$5.zip;

  /**
   * @alias KmlLookAt
   * @constructor
   *
   * @param {Cartesian3} position camera position
   * @param {HeadingPitchRange} headingPitchRange camera orientation
   */
  function KmlLookAt(position, headingPitchRange) {
    this.position = position;
    this.headingPitchRange = headingPitchRange;
  }

  /**
   * @alias KmlTour
   * @constructor
   *
   * @param {String} name name parsed from KML
   * @param {String} id id parsed from KML
   * @param {Array} playlist array with KMLTourFlyTos, KMLTourWaits and KMLTourSoundCues
   */
  function KmlTour(name, id) {
    /**
     * Id of kml gx:Tour entry
     * @type String
     */
    this.id = id;
    /**
     * Tour name
     * @type String
     */
    this.name = name;
    /**
     * Index of current entry from playlist
     * @type Number
     */
    this.playlistIndex = 0;
    /**
     * Array of playlist entries
     * @type Array
     */
    this.playlist = [];
    /**
     * Event will be called when tour starts to play,
     * before any playlist entry starts to play.
     * @type Event
     */
    this.tourStart = new Event();
    /**
     * Event will be called when all playlist entries are
     * played, or tour playback being canceled.
     *
     * If tour playback was terminated, event callback will
     * be called with terminated=true parameter.
     * @type Event
     */
    this.tourEnd = new Event();
    /**
     * Event will be called when entry from playlist starts to play.
     *
     * Event callback will be called with curent entry as first parameter.
     * @type Event
     */
    this.entryStart = new Event();
    /**
     * Event will be called when entry from playlist ends to play.
     *
     * Event callback will be called with following parameters:
     * 1. entry - entry
     * 2. terminated - true if playback was terminated by calling {@link KmlTour#stop}
     * @type Event
     */
    this.entryEnd = new Event();

    this._activeEntries = [];
  }

  /**
   * Add entry to this tour playlist.
   *
   * @param {KmlTourFlyTo|KmlTourWait} entry an entry to add to the playlist.
   */
  KmlTour.prototype.addPlaylistEntry = function (entry) {
    this.playlist.push(entry);
  };

  /**
   * Play this tour.
   *
   * @param {Viewer} viewer viewer widget.
   * @param {Object} [cameraOptions] these options will be merged with {@link Camera#flyTo}
   * options for FlyTo playlist entries.
   */
  KmlTour.prototype.play = function (viewer, cameraOptions) {
    this.tourStart.raiseEvent();

    var tour = this;
    playEntry.call(this, viewer, cameraOptions, function (terminated) {
      tour.playlistIndex = 0;
      // Stop nonblocking entries
      if (!terminated) {
        cancelAllEntries(tour._activeEntries);
      }
      tour.tourEnd.raiseEvent(terminated);
    });
  };

  /**
   * Stop curently playing tour.
   */
  KmlTour.prototype.stop = function () {
    cancelAllEntries(this._activeEntries);
  };

  // Stop all activeEntries.
  function cancelAllEntries(activeEntries) {
    for (
      var entry = activeEntries.pop();
      entry !== undefined;
      entry = activeEntries.pop()
    ) {
      entry.stop();
    }
  }

  // Play playlist entry.
  // This function is called recursevly with playNext and iterates over all entries from playlist.
  function playEntry(viewer, cameraOptions, allDone) {
    var entry = this.playlist[this.playlistIndex];
    if (entry) {
      var _playNext = playNext.bind(this, viewer, cameraOptions, allDone);
      this._activeEntries.push(entry);
      this.entryStart.raiseEvent(entry);
      if (entry.blocking) {
        entry.play(_playNext, viewer.scene.camera, cameraOptions);
      } else {
        var tour = this;
        entry.play(function () {
          tour.entryEnd.raiseEvent(entry);
          var indx = tour._activeEntries.indexOf(entry);
          if (indx >= 0) {
            tour._activeEntries.splice(indx, 1);
          }
        });
        _playNext(viewer, cameraOptions, allDone);
      }
    } else if (defined(allDone)) {
      allDone(false);
    }
  }

  // Increment playlistIndex and call playEntry if terminated isn't true.
  function playNext(viewer, cameraOptions, allDone, terminated) {
    var entry = this.playlist[this.playlistIndex];
    this.entryEnd.raiseEvent(entry, terminated);

    if (terminated) {
      allDone(terminated);
    } else {
      var indx = this._activeEntries.indexOf(entry);
      if (indx >= 0) {
        this._activeEntries.splice(indx, 1);
      }
      this.playlistIndex++;
      playEntry.call(this, viewer, cameraOptions, allDone);
    }
  }

  /**
   * @alias KmlTourFlyTo
   * @constructor
   *
   * @param {Number} duration entry duration
   * @param {String} flyToMode KML fly to mode: bounce, smooth, etc
   * @param {KmlCamera|KmlLookAt} view KmlCamera or KmlLookAt
   */
  function KmlTourFlyTo(duration, flyToMode, view) {
    this.type = "KmlTourFlyTo";
    this.blocking = true;
    this.activeCamera = null;
    this.activeCallback = null;

    this.duration = duration;
    this.view = view;
    this.flyToMode = flyToMode;
  }

  /**
   * Play this playlist entry
   *
   * @param {KmlTourFlyTo.DoneCallback} done function which will be called when playback ends
   * @param {Camera} camera Cesium camera
   * @param {Object} [cameraOptions] which will be merged with camera flyTo options. See {@link Camera#flyTo}
   */
  KmlTourFlyTo.prototype.play = function (done, camera, cameraOptions) {
    this.activeCamera = camera;
    if (defined(done) && done !== null) {
      var self = this;
      this.activeCallback = function (terminated) {
        delete self.activeCallback;
        delete self.activeCamera;
        done(defined(terminated) ? false : terminated);
      };
    }

    var options = this.getCameraOptions(cameraOptions);
    if (this.view.headingPitchRoll) {
      camera.flyTo(options);
    } else if (this.view.headingPitchRange) {
      var target = new BoundingSphere(this.view.position);
      camera.flyToBoundingSphere(target, options);
    }
  };

  /**
   * Stop execution of curent entry. Cancel camera flyTo
   */
  KmlTourFlyTo.prototype.stop = function () {
    if (defined(this.activeCamera)) {
      this.activeCamera.cancelFlight();
    }
    if (defined(this.activeCallback)) {
      this.activeCallback(true);
    }
  };

  /**
   * Returns options for {@link Camera#flyTo} or {@link Camera#flyToBoundingSphere}
   * depends on this.view type.
   *
   * @param {Object} cameraOptions options to merge with generated. See {@link Camera#flyTo}
   * @returns {Object} {@link Camera#flyTo} or {@link Camera#flyToBoundingSphere} options
   */
  KmlTourFlyTo.prototype.getCameraOptions = function (cameraOptions) {
    var options = {
      duration: this.duration,
    };

    if (defined(this.activeCallback)) {
      options.complete = this.activeCallback;
    }

    if (this.flyToMode === "smooth") {
      options.easingFunction = EasingFunction$1.LINEAR_NONE;
    }

    if (this.view.headingPitchRoll) {
      options.destination = this.view.position;
      options.orientation = this.view.headingPitchRoll;
    } else if (this.view.headingPitchRange) {
      options.offset = this.view.headingPitchRange;
    }

    if (defined(cameraOptions)) {
      options = combine(options, cameraOptions);
    }
    return options;
  };

  /**
   * @alias KmlTourWait
   * @constructor
   *
   * @param {Number} duration entry duration
   */
  function KmlTourWait(duration) {
    this.type = "KmlTourWait";
    this.blocking = true;
    this.duration = duration;

    this.timeout = null;
  }

  /**
   * Play this playlist entry
   *
   * @param {KmlTourWait.DoneCallback} done function which will be called when playback ends
   */
  KmlTourWait.prototype.play = function (done) {
    var self = this;
    this.activeCallback = done;
    this.timeout = setTimeout(function () {
      delete self.activeCallback;
      done(false);
    }, this.duration * 1000);
  };

  /**
   * Stop execution of curent entry, cancel curent timeout
   */
  KmlTourWait.prototype.stop = function () {
    clearTimeout(this.timeout);
    if (defined(this.activeCallback)) {
      this.activeCallback(true);
    }
  };

  //This is by no means an exhaustive list of MIME types.
  //The purpose of this list is to be able to accurately identify content embedded
  //in KMZ files. Eventually, we can make this configurable by the end user so they can add
  //there own content types if they have KMZ files that require it.
  var MimeTypes = {
    avi: "video/x-msvideo",
    bmp: "image/bmp",
    bz2: "application/x-bzip2",
    chm: "application/vnd.ms-htmlhelp",
    css: "text/css",
    csv: "text/csv",
    doc: "application/msword",
    dvi: "application/x-dvi",
    eps: "application/postscript",
    flv: "video/x-flv",
    gif: "image/gif",
    gz: "application/x-gzip",
    htm: "text/html",
    html: "text/html",
    ico: "image/vnd.microsoft.icon",
    jnlp: "application/x-java-jnlp-file",
    jpeg: "image/jpeg",
    jpg: "image/jpeg",
    m3u: "audio/x-mpegurl",
    m4v: "video/mp4",
    mathml: "application/mathml+xml",
    mid: "audio/midi",
    midi: "audio/midi",
    mov: "video/quicktime",
    mp3: "audio/mpeg",
    mp4: "video/mp4",
    mp4v: "video/mp4",
    mpeg: "video/mpeg",
    mpg: "video/mpeg",
    odp: "application/vnd.oasis.opendocument.presentation",
    ods: "application/vnd.oasis.opendocument.spreadsheet",
    odt: "application/vnd.oasis.opendocument.text",
    ogg: "application/ogg",
    pdf: "application/pdf",
    png: "image/png",
    pps: "application/vnd.ms-powerpoint",
    ppt: "application/vnd.ms-powerpoint",
    ps: "application/postscript",
    qt: "video/quicktime",
    rdf: "application/rdf+xml",
    rss: "application/rss+xml",
    rtf: "application/rtf",
    svg: "image/svg+xml",
    swf: "application/x-shockwave-flash",
    text: "text/plain",
    tif: "image/tiff",
    tiff: "image/tiff",
    txt: "text/plain",
    wav: "audio/x-wav",
    wma: "audio/x-ms-wma",
    wmv: "video/x-ms-wmv",
    xml: "application/xml",
    zip: "application/zip",

    detectFromFilename: function (filename) {
      var ext = filename.toLowerCase();
      ext = getExtensionFromUri(ext);
      return MimeTypes[ext];
    },
  };

  var parser;
  if (typeof DOMParser !== "undefined") {
    parser = new DOMParser();
  }

  var autolinker = new Autolinker({
    stripPrefix: false,
    email: false,
    replaceFn: function (match) {
      if (!match.protocolUrlMatch) {
        //Prevent matching of non-explicit urls.
        //i.e. foo.id won't match but http://foo.id will
        return false;
      }
    },
  });

  var BILLBOARD_SIZE = 32;

  var BILLBOARD_NEAR_DISTANCE = 2414016;
  var BILLBOARD_NEAR_RATIO = 1.0;
  var BILLBOARD_FAR_DISTANCE = 1.6093e7;
  var BILLBOARD_FAR_RATIO = 0.1;

  var kmlNamespaces = [
    null,
    undefined,
    "http://www.opengis.net/kml/2.2",
    "http://earth.google.com/kml/2.2",
    "http://earth.google.com/kml/2.1",
    "http://earth.google.com/kml/2.0",
  ];
  var gxNamespaces = ["http://www.google.com/kml/ext/2.2"];
  var atomNamespaces = ["http://www.w3.org/2005/Atom"];
  var namespaces = {
    kml: kmlNamespaces,
    gx: gxNamespaces,
    atom: atomNamespaces,
    kmlgx: kmlNamespaces.concat(gxNamespaces),
  };

  // Ensure Specs/Data/KML/unsupported.kml is kept up to date with these supported types
  var featureTypes = {
    Document: processDocument$1,
    Folder: processFolder,
    Placemark: processPlacemark,
    NetworkLink: processNetworkLink,
    GroundOverlay: processGroundOverlay,
    PhotoOverlay: processUnsupportedFeature,
    ScreenOverlay: processUnsupportedFeature,
    Tour: processTour,
  };

  function DeferredLoading(dataSource) {
    this._dataSource = dataSource;
    this._deferred = when.defer();
    this._stack = [];
    this._promises = [];
    this._timeoutSet = false;
    this._used = false;

    this._started = 0;
    this._timeThreshold = 1000; // Initial load is 1 second
  }

  Object.defineProperties(DeferredLoading.prototype, {
    dataSource: {
      get: function () {
        return this._dataSource;
      },
    },
  });

  DeferredLoading.prototype.addNodes = function (nodes, processingData) {
    this._stack.push({
      nodes: nodes,
      index: 0,
      processingData: processingData,
    });
    this._used = true;
  };

  DeferredLoading.prototype.addPromise = function (promise) {
    this._promises.push(promise);
  };

  DeferredLoading.prototype.wait = function () {
    // Case where we had a non-document/folder as the root
    var deferred = this._deferred;
    if (!this._used) {
      deferred.resolve();
    }

    return when.join(deferred.promise, when.all(this._promises));
  };

  DeferredLoading.prototype.process = function () {
    var isFirstCall = this._stack.length === 1;
    if (isFirstCall) {
      this._started = KmlDataSource._getTimestamp();
    }

    return this._process(isFirstCall);
  };

  DeferredLoading.prototype._giveUpTime = function () {
    if (this._timeoutSet) {
      // Timeout was already set so just return
      return;
    }

    this._timeoutSet = true;
    this._timeThreshold = 50; // After the first load lower threshold to 0.5 seconds
    var that = this;
    setTimeout(function () {
      that._timeoutSet = false;
      that._started = KmlDataSource._getTimestamp();
      that._process(true);
    }, 0);
  };

  DeferredLoading.prototype._nextNode = function () {
    var stack = this._stack;
    var top = stack[stack.length - 1];
    var index = top.index;
    var nodes = top.nodes;
    if (index === nodes.length) {
      return;
    }
    ++top.index;

    return nodes[index];
  };

  DeferredLoading.prototype._pop = function () {
    var stack = this._stack;
    stack.pop();

    // Return false if we are done
    if (stack.length === 0) {
      this._deferred.resolve();
      return false;
    }

    return true;
  };

  DeferredLoading.prototype._process = function (isFirstCall) {
    var dataSource = this.dataSource;
    var processingData = this._stack[this._stack.length - 1].processingData;

    var child = this._nextNode();
    while (defined(child)) {
      var featureProcessor = featureTypes[child.localName];
      if (
        defined(featureProcessor) &&
        (namespaces.kml.indexOf(child.namespaceURI) !== -1 ||
          namespaces.gx.indexOf(child.namespaceURI) !== -1)
      ) {
        featureProcessor(dataSource, child, processingData, this);

        // Give up time and continue loading later
        if (
          this._timeoutSet ||
          KmlDataSource._getTimestamp() > this._started + this._timeThreshold
        ) {
          this._giveUpTime();
          return;
        }
      }

      child = this._nextNode();
    }

    // If we are a recursive call from a subfolder, just return so the parent folder can continue processing
    // If we aren't then make another call to processNodes because there is stuff still left in the queue
    if (this._pop() && isFirstCall) {
      this._process(true);
    }
  };

  function isZipFile(blob) {
    var magicBlob = blob.slice(0, Math.min(4, blob.size));
    var deferred = when.defer();
    var reader = new FileReader();
    reader.addEventListener("load", function () {
      deferred.resolve(
        new DataView(reader.result).getUint32(0, false) === 0x504b0304
      );
    });
    reader.addEventListener("error", function () {
      deferred.reject(reader.error);
    });
    reader.readAsArrayBuffer(magicBlob);
    return deferred.promise;
  }

  function readBlobAsText(blob) {
    var deferred = when.defer();
    var reader = new FileReader();
    reader.addEventListener("load", function () {
      deferred.resolve(reader.result);
    });
    reader.addEventListener("error", function () {
      deferred.reject(reader.error);
    });
    reader.readAsText(blob);
    return deferred.promise;
  }

  function insertNamespaces(text) {
    var namespaceMap = {
      xsi: "http://www.w3.org/2001/XMLSchema-instance",
    };
    var firstPart, lastPart, reg, declaration;

    for (var key in namespaceMap) {
      if (namespaceMap.hasOwnProperty(key)) {
        reg = RegExp("[< ]" + key + ":");
        declaration = "xmlns:" + key + "=";
        if (reg.test(text) && text.indexOf(declaration) === -1) {
          if (!defined(firstPart)) {
            firstPart = text.substr(0, text.indexOf("<kml") + 4);
            lastPart = text.substr(firstPart.length);
          }
          firstPart += " " + declaration + '"' + namespaceMap[key] + '"';
        }
      }
    }

    if (defined(firstPart)) {
      text = firstPart + lastPart;
    }

    return text;
  }

  function removeDuplicateNamespaces(text) {
    var index = text.indexOf("xmlns:");
    var endDeclaration = text.indexOf(">", index);
    var namespace, startIndex, endIndex;

    while (index !== -1 && index < endDeclaration) {
      namespace = text.slice(index, text.indexOf('"', index));
      startIndex = index;
      index = text.indexOf(namespace, index + 1);
      if (index !== -1) {
        endIndex = text.indexOf('"', text.indexOf('"', index) + 1);
        text = text.slice(0, index - 1) + text.slice(endIndex + 1, text.length);
        index = text.indexOf("xmlns:", startIndex - 1);
      } else {
        index = text.indexOf("xmlns:", startIndex + 1);
      }
    }

    return text;
  }

  function loadXmlFromZip(entry, uriResolver, deferred) {
    entry.getData(new zip.TextWriter(), function (text) {
      text = insertNamespaces(text);
      text = removeDuplicateNamespaces(text);
      uriResolver.kml = parser.parseFromString(text, "application/xml");
      deferred.resolve();
    });
  }

  function loadDataUriFromZip(entry, uriResolver, deferred) {
    var mimeType = defaultValue(
      MimeTypes.detectFromFilename(entry.filename),
      "application/octet-stream"
    );
    entry.getData(new zip.Data64URIWriter(mimeType), function (dataUri) {
      uriResolver[entry.filename] = dataUri;
      deferred.resolve();
    });
  }

  function embedDataUris(div, elementType, attributeName, uriResolver) {
    var keys = uriResolver.keys;
    var baseUri = new URI(".");
    var elements = div.querySelectorAll(elementType);
    for (var i = 0; i < elements.length; i++) {
      var element = elements[i];
      var value = element.getAttribute(attributeName);
      var uri = new URI(value).resolve(baseUri).toString();
      var index = keys.indexOf(uri);
      if (index !== -1) {
        var key = keys[index];
        element.setAttribute(attributeName, uriResolver[key]);
        if (elementType === "a" && element.getAttribute("download") === null) {
          element.setAttribute("download", key);
        }
      }
    }
  }

  function applyBasePath(div, elementType, attributeName, sourceResource) {
    var elements = div.querySelectorAll(elementType);
    for (var i = 0; i < elements.length; i++) {
      var element = elements[i];
      var value = element.getAttribute(attributeName);
      var resource = resolveHref(value, sourceResource);
      element.setAttribute(attributeName, resource.url);
    }
  }

  // an optional context is passed to allow for some malformed kmls (those with multiple geometries with same ids) to still parse
  // correctly, as they do in Google Earth.
  function createEntity(node, entityCollection, context) {
    var id = queryStringAttribute(node, "id");
    id = defined(id) && id.length !== 0 ? id : createGuid();
    if (defined(context)) {
      id = context + id;
    }

    // If we have a duplicate ID just generate one.
    // This isn't valid KML but Google Earth handles this case.
    var entity = entityCollection.getById(id);
    if (defined(entity)) {
      id = createGuid();
      if (defined(context)) {
        id = context + id;
      }
    }

    entity = entityCollection.add(new Entity({ id: id }));
    if (!defined(entity.kml)) {
      entity.addProperty("kml");
      entity.kml = new KmlFeatureData();
    }
    return entity;
  }

  function isExtrudable(altitudeMode, gxAltitudeMode) {
    return (
      altitudeMode === "absolute" ||
      altitudeMode === "relativeToGround" ||
      gxAltitudeMode === "relativeToSeaFloor"
    );
  }

  function readCoordinate(value, ellipsoid) {
    //Google Earth treats empty or missing coordinates as 0.
    if (!defined(value)) {
      return Cartesian3.fromDegrees(0, 0, 0, ellipsoid);
    }

    var digits = value.match(/[^\s,\n]+/g);
    if (!defined(digits)) {
      return Cartesian3.fromDegrees(0, 0, 0, ellipsoid);
    }

    var longitude = parseFloat(digits[0]);
    var latitude = parseFloat(digits[1]);
    var height = parseFloat(digits[2]);

    longitude = isNaN(longitude) ? 0.0 : longitude;
    latitude = isNaN(latitude) ? 0.0 : latitude;
    height = isNaN(height) ? 0.0 : height;

    return Cartesian3.fromDegrees(longitude, latitude, height, ellipsoid);
  }

  function readCoordinates(element, ellipsoid) {
    if (!defined(element)) {
      return undefined;
    }

    var tuples = element.textContent.match(/[^\s\n]+/g);
    if (!defined(tuples)) {
      return undefined;
    }

    var length = tuples.length;
    var result = new Array(length);
    var resultIndex = 0;
    for (var i = 0; i < length; i++) {
      result[resultIndex++] = readCoordinate(tuples[i], ellipsoid);
    }
    return result;
  }

  function queryNumericAttribute(node, attributeName) {
    if (!defined(node)) {
      return undefined;
    }

    var value = node.getAttribute(attributeName);
    if (value !== null) {
      var result = parseFloat(value);
      return !isNaN(result) ? result : undefined;
    }
    return undefined;
  }

  function queryStringAttribute(node, attributeName) {
    if (!defined(node)) {
      return undefined;
    }
    var value = node.getAttribute(attributeName);
    return value !== null ? value : undefined;
  }

  function queryFirstNode(node, tagName, namespace) {
    if (!defined(node)) {
      return undefined;
    }
    var childNodes = node.childNodes;
    var length = childNodes.length;
    for (var q = 0; q < length; q++) {
      var child = childNodes[q];
      if (
        child.localName === tagName &&
        namespace.indexOf(child.namespaceURI) !== -1
      ) {
        return child;
      }
    }
    return undefined;
  }

  function queryNodes(node, tagName, namespace) {
    if (!defined(node)) {
      return undefined;
    }
    var result = [];
    var childNodes = node.getElementsByTagNameNS("*", tagName);
    var length = childNodes.length;
    for (var q = 0; q < length; q++) {
      var child = childNodes[q];
      if (
        child.localName === tagName &&
        namespace.indexOf(child.namespaceURI) !== -1
      ) {
        result.push(child);
      }
    }
    return result;
  }

  function queryChildNodes(node, tagName, namespace) {
    if (!defined(node)) {
      return [];
    }
    var result = [];
    var childNodes = node.childNodes;
    var length = childNodes.length;
    for (var q = 0; q < length; q++) {
      var child = childNodes[q];
      if (
        child.localName === tagName &&
        namespace.indexOf(child.namespaceURI) !== -1
      ) {
        result.push(child);
      }
    }
    return result;
  }

  function queryNumericValue(node, tagName, namespace) {
    var resultNode = queryFirstNode(node, tagName, namespace);
    if (defined(resultNode)) {
      var result = parseFloat(resultNode.textContent);
      return !isNaN(result) ? result : undefined;
    }
    return undefined;
  }

  function queryStringValue(node, tagName, namespace) {
    var result = queryFirstNode(node, tagName, namespace);
    if (defined(result)) {
      return result.textContent.trim();
    }
    return undefined;
  }

  function queryBooleanValue(node, tagName, namespace) {
    var result = queryFirstNode(node, tagName, namespace);
    if (defined(result)) {
      var value = result.textContent.trim();
      return value === "1" || /^true$/i.test(value);
    }
    return undefined;
  }

  function resolveHref(href, sourceResource, uriResolver) {
    if (!defined(href)) {
      return undefined;
    }

    var resource;
    if (defined(uriResolver)) {
      // To resolve issues with KML sources defined in Windows style paths.
      href = href.replace(/\\/g, "/");
      var blob = uriResolver[href];
      if (defined(blob)) {
        resource = new Resource({
          url: blob,
        });
      } else {
        // Needed for multiple levels of KML files in a KMZ
        var baseUri = new URI(sourceResource.getUrlComponent());
        var uri = new URI(href);
        blob = uriResolver[uri.resolve(baseUri)];
        if (defined(blob)) {
          resource = new Resource({
            url: blob,
          });
        }
      }
    }

    if (!defined(resource)) {
      resource = sourceResource.getDerivedResource({
        url: href,
      });
    }

    return resource;
  }

  var colorOptions = {
    maximumRed: undefined,
    red: undefined,
    maximumGreen: undefined,
    green: undefined,
    maximumBlue: undefined,
    blue: undefined,
  };

  function parseColorString(value, isRandom) {
    if (!defined(value) || /^\s*$/gm.test(value)) {
      return undefined;
    }

    if (value[0] === "#") {
      value = value.substring(1);
    }

    var alpha = parseInt(value.substring(0, 2), 16) / 255.0;
    var blue = parseInt(value.substring(2, 4), 16) / 255.0;
    var green = parseInt(value.substring(4, 6), 16) / 255.0;
    var red = parseInt(value.substring(6, 8), 16) / 255.0;

    if (!isRandom) {
      return new Color(red, green, blue, alpha);
    }

    if (red > 0) {
      colorOptions.maximumRed = red;
      colorOptions.red = undefined;
    } else {
      colorOptions.maximumRed = undefined;
      colorOptions.red = 0;
    }
    if (green > 0) {
      colorOptions.maximumGreen = green;
      colorOptions.green = undefined;
    } else {
      colorOptions.maximumGreen = undefined;
      colorOptions.green = 0;
    }
    if (blue > 0) {
      colorOptions.maximumBlue = blue;
      colorOptions.blue = undefined;
    } else {
      colorOptions.maximumBlue = undefined;
      colorOptions.blue = 0;
    }
    colorOptions.alpha = alpha;
    return Color.fromRandom(colorOptions);
  }

  function queryColorValue(node, tagName, namespace) {
    var value = queryStringValue(node, tagName, namespace);
    if (!defined(value)) {
      return undefined;
    }
    return parseColorString(
      value,
      queryStringValue(node, "colorMode", namespace) === "random"
    );
  }

  function processTimeStamp(featureNode) {
    var node = queryFirstNode(featureNode, "TimeStamp", namespaces.kmlgx);
    var whenString = queryStringValue(node, "when", namespaces.kmlgx);

    if (!defined(node) || !defined(whenString) || whenString.length === 0) {
      return undefined;
    }

    //According to the KML spec, a TimeStamp represents a "single moment in time"
    //However, since Cesium animates much differently than Google Earth, that doesn't
    //Make much sense here.  Instead, we use the TimeStamp as the moment the feature
    //comes into existence.  This works much better and gives a similar feel to
    //GE's experience.
    var when = JulianDate.fromIso8601(whenString);
    var result = new TimeIntervalCollection();
    result.addInterval(
      new TimeInterval({
        start: when,
        stop: Iso8601.MAXIMUM_VALUE,
      })
    );
    return result;
  }

  function processTimeSpan(featureNode) {
    var node = queryFirstNode(featureNode, "TimeSpan", namespaces.kmlgx);
    if (!defined(node)) {
      return undefined;
    }
    var result;

    var beginNode = queryFirstNode(node, "begin", namespaces.kmlgx);
    var beginDate = defined(beginNode)
      ? JulianDate.fromIso8601(beginNode.textContent)
      : undefined;

    var endNode = queryFirstNode(node, "end", namespaces.kmlgx);
    var endDate = defined(endNode)
      ? JulianDate.fromIso8601(endNode.textContent)
      : undefined;

    if (defined(beginDate) && defined(endDate)) {
      if (JulianDate.lessThan(endDate, beginDate)) {
        var tmp = beginDate;
        beginDate = endDate;
        endDate = tmp;
      }
      result = new TimeIntervalCollection();
      result.addInterval(
        new TimeInterval({
          start: beginDate,
          stop: endDate,
        })
      );
    } else if (defined(beginDate)) {
      result = new TimeIntervalCollection();
      result.addInterval(
        new TimeInterval({
          start: beginDate,
          stop: Iso8601.MAXIMUM_VALUE,
        })
      );
    } else if (defined(endDate)) {
      result = new TimeIntervalCollection();
      result.addInterval(
        new TimeInterval({
          start: Iso8601.MINIMUM_VALUE,
          stop: endDate,
        })
      );
    }

    return result;
  }

  function createDefaultBillboard() {
    var billboard = new BillboardGraphics();
    billboard.width = BILLBOARD_SIZE;
    billboard.height = BILLBOARD_SIZE;
    billboard.scaleByDistance = new NearFarScalar(
      BILLBOARD_NEAR_DISTANCE,
      BILLBOARD_NEAR_RATIO,
      BILLBOARD_FAR_DISTANCE,
      BILLBOARD_FAR_RATIO
    );
    billboard.pixelOffsetScaleByDistance = new NearFarScalar(
      BILLBOARD_NEAR_DISTANCE,
      BILLBOARD_NEAR_RATIO,
      BILLBOARD_FAR_DISTANCE,
      BILLBOARD_FAR_RATIO
    );
    return billboard;
  }

  function createDefaultPolygon() {
    var polygon = new PolygonGraphics();
    polygon.outline = true;
    polygon.outlineColor = Color.WHITE;
    return polygon;
  }

  function createDefaultLabel() {
    var label = new LabelGraphics();
    label.translucencyByDistance = new NearFarScalar(3000000, 1.0, 5000000, 0.0);
    label.pixelOffset = new Cartesian2(17, 0);
    label.horizontalOrigin = HorizontalOrigin$1.LEFT;
    label.font = "16px sans-serif";
    label.style = LabelStyle$1.FILL_AND_OUTLINE;
    return label;
  }

  function getIconHref(
    iconNode,
    dataSource,
    sourceResource,
    uriResolver,
    canRefresh
  ) {
    var href = queryStringValue(iconNode, "href", namespaces.kml);
    if (!defined(href) || href.length === 0) {
      return undefined;
    }

    if (href.indexOf("root://icons/palette-") === 0) {
      var palette = href.charAt(21);

      // Get the icon number
      var x = defaultValue(queryNumericValue(iconNode, "x", namespaces.gx), 0);
      var y = defaultValue(queryNumericValue(iconNode, "y", namespaces.gx), 0);
      x = Math.min(x / 32, 7);
      y = 7 - Math.min(y / 32, 7);
      var iconNum = 8 * y + x;

      href =
        "https://maps.google.com/mapfiles/kml/pal" +
        palette +
        "/icon" +
        iconNum +
        ".png";
    }

    var hrefResource = resolveHref(href, sourceResource, uriResolver);

    if (canRefresh) {
      var refreshMode = queryStringValue(iconNode, "refreshMode", namespaces.kml);
      var viewRefreshMode = queryStringValue(
        iconNode,
        "viewRefreshMode",
        namespaces.kml
      );
      if (refreshMode === "onInterval" || refreshMode === "onExpire") {
        oneTimeWarning(
          "kml-refreshMode-" + refreshMode,
          "KML - Unsupported Icon refreshMode: " + refreshMode
        );
      } else if (viewRefreshMode === "onStop" || viewRefreshMode === "onRegion") {
        oneTimeWarning(
          "kml-refreshMode-" + viewRefreshMode,
          "KML - Unsupported Icon viewRefreshMode: " + viewRefreshMode
        );
      }

      var viewBoundScale = defaultValue(
        queryStringValue(iconNode, "viewBoundScale", namespaces.kml),
        1.0
      );
      var defaultViewFormat =
        viewRefreshMode === "onStop"
          ? "BBOX=[bboxWest],[bboxSouth],[bboxEast],[bboxNorth]"
          : "";
      var viewFormat = defaultValue(
        queryStringValue(iconNode, "viewFormat", namespaces.kml),
        defaultViewFormat
      );
      var httpQuery = queryStringValue(iconNode, "httpQuery", namespaces.kml);
      if (defined(viewFormat)) {
        hrefResource.setQueryParameters(queryToObject(cleanupString(viewFormat)));
      }
      if (defined(httpQuery)) {
        hrefResource.setQueryParameters(queryToObject(cleanupString(httpQuery)));
      }

      var ellipsoid = dataSource._ellipsoid;
      processNetworkLinkQueryString(
        hrefResource,
        dataSource._camera,
        dataSource._canvas,
        viewBoundScale,
        dataSource._lastCameraView.bbox,
        ellipsoid
      );

      return hrefResource;
    }

    return hrefResource;
  }

  function processBillboardIcon(
    dataSource,
    node,
    targetEntity,
    sourceResource,
    uriResolver
  ) {
    var scale = queryNumericValue(node, "scale", namespaces.kml);
    var heading = queryNumericValue(node, "heading", namespaces.kml);
    var color = queryColorValue(node, "color", namespaces.kml);

    var iconNode = queryFirstNode(node, "Icon", namespaces.kml);
    var icon = getIconHref(
      iconNode,
      dataSource,
      sourceResource,
      uriResolver,
      false
    );

    // If icon tags are present but blank, we do not want to show an icon
    if (defined(iconNode) && !defined(icon)) {
      icon = false;
    }

    var x = queryNumericValue(iconNode, "x", namespaces.gx);
    var y = queryNumericValue(iconNode, "y", namespaces.gx);
    var w = queryNumericValue(iconNode, "w", namespaces.gx);
    var h = queryNumericValue(iconNode, "h", namespaces.gx);

    var hotSpotNode = queryFirstNode(node, "hotSpot", namespaces.kml);
    var hotSpotX = queryNumericAttribute(hotSpotNode, "x");
    var hotSpotY = queryNumericAttribute(hotSpotNode, "y");
    var hotSpotXUnit = queryStringAttribute(hotSpotNode, "xunits");
    var hotSpotYUnit = queryStringAttribute(hotSpotNode, "yunits");

    var billboard = targetEntity.billboard;
    if (!defined(billboard)) {
      billboard = createDefaultBillboard();
      targetEntity.billboard = billboard;
    }

    billboard.image = icon;
    billboard.scale = scale;
    billboard.color = color;

    if (defined(x) || defined(y) || defined(w) || defined(h)) {
      billboard.imageSubRegion = new BoundingRectangle(x, y, w, h);
    }

    //GE treats a heading of zero as no heading
    //You can still point north using a 360 degree angle (or any multiple of 360)
    if (defined(heading) && heading !== 0) {
      billboard.rotation = CesiumMath.toRadians(-heading);
      billboard.alignedAxis = Cartesian3.UNIT_Z;
    }

    //Hotpot is the KML equivalent of pixel offset
    //The hotspot origin is the lower left, but we leave
    //our billboard origin at the center and simply
    //modify the pixel offset to take this into account
    scale = defaultValue(scale, 1.0);

    var xOffset;
    var yOffset;
    if (defined(hotSpotX)) {
      if (hotSpotXUnit === "pixels") {
        xOffset = -hotSpotX * scale;
      } else if (hotSpotXUnit === "insetPixels") {
        xOffset = (hotSpotX - BILLBOARD_SIZE) * scale;
      } else if (hotSpotXUnit === "fraction") {
        xOffset = -hotSpotX * BILLBOARD_SIZE * scale;
      }
      xOffset += BILLBOARD_SIZE * 0.5 * scale;
    }

    if (defined(hotSpotY)) {
      if (hotSpotYUnit === "pixels") {
        yOffset = hotSpotY * scale;
      } else if (hotSpotYUnit === "insetPixels") {
        yOffset = (-hotSpotY + BILLBOARD_SIZE) * scale;
      } else if (hotSpotYUnit === "fraction") {
        yOffset = hotSpotY * BILLBOARD_SIZE * scale;
      }

      yOffset -= BILLBOARD_SIZE * 0.5 * scale;
    }

    if (defined(xOffset) || defined(yOffset)) {
      billboard.pixelOffset = new Cartesian2(xOffset, yOffset);
    }
  }

  function applyStyle(
    dataSource,
    styleNode,
    targetEntity,
    sourceResource,
    uriResolver
  ) {
    for (var i = 0, len = styleNode.childNodes.length; i < len; i++) {
      var node = styleNode.childNodes.item(i);
      if (node.localName === "IconStyle") {
        processBillboardIcon(
          dataSource,
          node,
          targetEntity,
          sourceResource,
          uriResolver
        );
      } else if (node.localName === "LabelStyle") {
        var label = targetEntity.label;
        if (!defined(label)) {
          label = createDefaultLabel();
          targetEntity.label = label;
        }
        label.scale = defaultValue(
          queryNumericValue(node, "scale", namespaces.kml),
          label.scale
        );
        label.fillColor = defaultValue(
          queryColorValue(node, "color", namespaces.kml),
          label.fillColor
        );
        label.text = targetEntity.name;
      } else if (node.localName === "LineStyle") {
        var polyline = targetEntity.polyline;
        if (!defined(polyline)) {
          polyline = new PolylineGraphics();
          targetEntity.polyline = polyline;
        }
        polyline.width = queryNumericValue(node, "width", namespaces.kml);
        polyline.material = queryColorValue(node, "color", namespaces.kml);
        if (defined(queryColorValue(node, "outerColor", namespaces.gx))) {
          oneTimeWarning(
            "kml-gx:outerColor",
            "KML - gx:outerColor is not supported in a LineStyle"
          );
        }
        if (defined(queryNumericValue(node, "outerWidth", namespaces.gx))) {
          oneTimeWarning(
            "kml-gx:outerWidth",
            "KML - gx:outerWidth is not supported in a LineStyle"
          );
        }
        if (defined(queryNumericValue(node, "physicalWidth", namespaces.gx))) {
          oneTimeWarning(
            "kml-gx:physicalWidth",
            "KML - gx:physicalWidth is not supported in a LineStyle"
          );
        }
        if (defined(queryBooleanValue(node, "labelVisibility", namespaces.gx))) {
          oneTimeWarning(
            "kml-gx:labelVisibility",
            "KML - gx:labelVisibility is not supported in a LineStyle"
          );
        }
      } else if (node.localName === "PolyStyle") {
        var polygon = targetEntity.polygon;
        if (!defined(polygon)) {
          polygon = createDefaultPolygon();
          targetEntity.polygon = polygon;
        }
        polygon.material = defaultValue(
          queryColorValue(node, "color", namespaces.kml),
          polygon.material
        );
        polygon.fill = defaultValue(
          queryBooleanValue(node, "fill", namespaces.kml),
          polygon.fill
        );
        polygon.outline = defaultValue(
          queryBooleanValue(node, "outline", namespaces.kml),
          polygon.outline
        );
      } else if (node.localName === "BalloonStyle") {
        var bgColor = defaultValue(
          parseColorString(queryStringValue(node, "bgColor", namespaces.kml)),
          Color.WHITE
        );
        var textColor = defaultValue(
          parseColorString(queryStringValue(node, "textColor", namespaces.kml)),
          Color.BLACK
        );
        var text = queryStringValue(node, "text", namespaces.kml);

        //This is purely an internal property used in style processing,
        //it never ends up on the final entity.
        targetEntity.addProperty("balloonStyle");
        targetEntity.balloonStyle = {
          bgColor: bgColor,
          textColor: textColor,
          text: text,
        };
      } else if (node.localName === "ListStyle") {
        var listItemType = queryStringValue(node, "listItemType", namespaces.kml);
        if (listItemType === "radioFolder" || listItemType === "checkOffOnly") {
          oneTimeWarning(
            "kml-listStyle-" + listItemType,
            "KML - Unsupported ListStyle with listItemType: " + listItemType
          );
        }
      }
    }
  }

  //Processes and merges any inline styles for the provided node into the provided entity.
  function computeFinalStyle(
    dataSource,
    placeMark,
    styleCollection,
    sourceResource,
    uriResolver
  ) {
    var result = new Entity();
    var styleEntity;

    //Google earth seems to always use the last inline Style/StyleMap only
    var styleIndex = -1;
    var childNodes = placeMark.childNodes;
    var length = childNodes.length;
    for (var q = 0; q < length; q++) {
      var child = childNodes[q];
      if (child.localName === "Style" || child.localName === "StyleMap") {
        styleIndex = q;
      }
    }

    if (styleIndex !== -1) {
      var inlineStyleNode = childNodes[styleIndex];
      if (inlineStyleNode.localName === "Style") {
        applyStyle(
          dataSource,
          inlineStyleNode,
          result,
          sourceResource,
          uriResolver
        );
      } else {
        // StyleMap
        var pairs = queryChildNodes(inlineStyleNode, "Pair", namespaces.kml);
        for (var p = 0; p < pairs.length; p++) {
          var pair = pairs[p];
          var key = queryStringValue(pair, "key", namespaces.kml);
          if (key === "normal") {
            var styleUrl = queryStringValue(pair, "styleUrl", namespaces.kml);
            if (defined(styleUrl)) {
              styleEntity = styleCollection.getById(styleUrl);
              if (!defined(styleEntity)) {
                styleEntity = styleCollection.getById("#" + styleUrl);
              }
              if (defined(styleEntity)) {
                result.merge(styleEntity);
              }
            } else {
              var node = queryFirstNode(pair, "Style", namespaces.kml);
              applyStyle(dataSource, node, result, sourceResource, uriResolver);
            }
          } else {
            oneTimeWarning(
              "kml-styleMap-" + key,
              "KML - Unsupported StyleMap key: " + key
            );
          }
        }
      }
    }

    //Google earth seems to always use the first external style only.
    var externalStyle = queryStringValue(placeMark, "styleUrl", namespaces.kml);
    if (defined(externalStyle)) {
      var id = externalStyle;
      if (externalStyle[0] !== "#" && externalStyle.indexOf("#") !== -1) {
        var tokens = externalStyle.split("#");
        var uri = tokens[0];
        var resource = sourceResource.getDerivedResource({
          url: uri,
        });

        id = resource.getUrlComponent() + "#" + tokens[1];
      }

      styleEntity = styleCollection.getById(id);
      if (!defined(styleEntity)) {
        styleEntity = styleCollection.getById("#" + id);
      }
      if (defined(styleEntity)) {
        result.merge(styleEntity);
      }
    }

    return result;
  }

  //Asynchronously processes an external style file.
  function processExternalStyles(dataSource, resource, styleCollection) {
    return resource.fetchXML().then(function (styleKml) {
      return processStyles(dataSource, styleKml, styleCollection, resource, true);
    });
  }

  //Processes all shared and external styles and stores
  //their id into the provided styleCollection.
  //Returns an array of promises that will resolve when
  //each style is loaded.
  function processStyles(
    dataSource,
    kml,
    styleCollection,
    sourceResource,
    isExternal,
    uriResolver
  ) {
    var i;
    var id;
    var styleEntity;

    var node;
    var styleNodes = queryNodes(kml, "Style", namespaces.kml);
    if (defined(styleNodes)) {
      var styleNodesLength = styleNodes.length;
      for (i = 0; i < styleNodesLength; i++) {
        node = styleNodes[i];
        id = queryStringAttribute(node, "id");
        if (defined(id)) {
          id = "#" + id;
          if (isExternal && defined(sourceResource)) {
            id = sourceResource.getUrlComponent() + id;
          }
          if (!defined(styleCollection.getById(id))) {
            styleEntity = new Entity({
              id: id,
            });
            styleCollection.add(styleEntity);
            applyStyle(
              dataSource,
              node,
              styleEntity,
              sourceResource,
              uriResolver
            );
          }
        }
      }
    }

    var styleMaps = queryNodes(kml, "StyleMap", namespaces.kml);
    if (defined(styleMaps)) {
      var styleMapsLength = styleMaps.length;
      for (i = 0; i < styleMapsLength; i++) {
        var styleMap = styleMaps[i];
        id = queryStringAttribute(styleMap, "id");
        if (defined(id)) {
          var pairs = queryChildNodes(styleMap, "Pair", namespaces.kml);
          for (var p = 0; p < pairs.length; p++) {
            var pair = pairs[p];
            var key = queryStringValue(pair, "key", namespaces.kml);
            if (key === "normal") {
              id = "#" + id;
              if (isExternal && defined(sourceResource)) {
                id = sourceResource.getUrlComponent() + id;
              }
              if (!defined(styleCollection.getById(id))) {
                styleEntity = styleCollection.getOrCreateEntity(id);

                var styleUrl = queryStringValue(pair, "styleUrl", namespaces.kml);
                if (defined(styleUrl)) {
                  if (styleUrl[0] !== "#") {
                    styleUrl = "#" + styleUrl;
                  }

                  if (isExternal && defined(sourceResource)) {
                    styleUrl = sourceResource.getUrlComponent() + styleUrl;
                  }
                  var base = styleCollection.getById(styleUrl);

                  if (defined(base)) {
                    styleEntity.merge(base);
                  }
                } else {
                  node = queryFirstNode(pair, "Style", namespaces.kml);
                  applyStyle(
                    dataSource,
                    node,
                    styleEntity,
                    sourceResource,
                    uriResolver
                  );
                }
              }
            } else {
              oneTimeWarning(
                "kml-styleMap-" + key,
                "KML - Unsupported StyleMap key: " + key
              );
            }
          }
        }
      }
    }

    var promises = [];
    var styleUrlNodes = kml.getElementsByTagName("styleUrl");
    var styleUrlNodesLength = styleUrlNodes.length;
    for (i = 0; i < styleUrlNodesLength; i++) {
      var styleReference = styleUrlNodes[i].textContent;
      if (styleReference[0] !== "#") {
        //According to the spec, all local styles should start with a #
        //and everything else is an external style that has a # seperating
        //the URL of the document and the style.  However, Google Earth
        //also accepts styleUrls without a # as meaning a local style.
        var tokens = styleReference.split("#");
        if (tokens.length === 2) {
          var uri = tokens[0];
          var resource = sourceResource.getDerivedResource({
            url: uri,
          });

          promises.push(
            processExternalStyles(dataSource, resource, styleCollection)
          );
        }
      }
    }

    return promises;
  }

  function createDropLine(entityCollection, entity, styleEntity) {
    var entityPosition = new ReferenceProperty(entityCollection, entity.id, [
      "position",
    ]);
    var surfacePosition = new ScaledPositionProperty(entity.position);
    entity.polyline = defined(styleEntity.polyline)
      ? styleEntity.polyline.clone()
      : new PolylineGraphics();
    entity.polyline.positions = new PositionPropertyArray([
      entityPosition,
      surfacePosition,
    ]);
  }

  function heightReferenceFromAltitudeMode(altitudeMode, gxAltitudeMode) {
    if (
      (!defined(altitudeMode) && !defined(gxAltitudeMode)) ||
      altitudeMode === "clampToGround"
    ) {
      return HeightReference$1.CLAMP_TO_GROUND;
    }

    if (altitudeMode === "relativeToGround") {
      return HeightReference$1.RELATIVE_TO_GROUND;
    }

    if (altitudeMode === "absolute") {
      return HeightReference$1.NONE;
    }

    if (gxAltitudeMode === "clampToSeaFloor") {
      oneTimeWarning(
        "kml-gx:altitudeMode-clampToSeaFloor",
        "KML - <gx:altitudeMode>:clampToSeaFloor is currently not supported, using <kml:altitudeMode>:clampToGround."
      );
      return HeightReference$1.CLAMP_TO_GROUND;
    }

    if (gxAltitudeMode === "relativeToSeaFloor") {
      oneTimeWarning(
        "kml-gx:altitudeMode-relativeToSeaFloor",
        "KML - <gx:altitudeMode>:relativeToSeaFloor is currently not supported, using <kml:altitudeMode>:relativeToGround."
      );
      return HeightReference$1.RELATIVE_TO_GROUND;
    }

    if (defined(altitudeMode)) {
      oneTimeWarning(
        "kml-altitudeMode-unknown",
        "KML - Unknown <kml:altitudeMode>:" +
          altitudeMode +
          ", using <kml:altitudeMode>:CLAMP_TO_GROUND."
      );
    } else {
      oneTimeWarning(
        "kml-gx:altitudeMode-unknown",
        "KML - Unknown <gx:altitudeMode>:" +
          gxAltitudeMode +
          ", using <kml:altitudeMode>:CLAMP_TO_GROUND."
      );
    }

    // Clamp to ground is the default
    return HeightReference$1.CLAMP_TO_GROUND;
  }

  function createPositionPropertyFromAltitudeMode(
    property,
    altitudeMode,
    gxAltitudeMode
  ) {
    if (
      gxAltitudeMode === "relativeToSeaFloor" ||
      altitudeMode === "absolute" ||
      altitudeMode === "relativeToGround"
    ) {
      //Just return the ellipsoid referenced property until we support MSL
      return property;
    }

    if (
      (defined(altitudeMode) && altitudeMode !== "clampToGround") || //
      (defined(gxAltitudeMode) && gxAltitudeMode !== "clampToSeaFloor")
    ) {
      oneTimeWarning(
        "kml-altitudeMode-unknown",
        "KML - Unknown altitudeMode: " +
          defaultValue(altitudeMode, gxAltitudeMode)
      );
    }

    // Clamp to ground is the default
    return new ScaledPositionProperty(property);
  }

  function createPositionPropertyArrayFromAltitudeMode(
    properties,
    altitudeMode,
    gxAltitudeMode,
    ellipsoid
  ) {
    if (!defined(properties)) {
      return undefined;
    }

    if (
      gxAltitudeMode === "relativeToSeaFloor" ||
      altitudeMode === "absolute" ||
      altitudeMode === "relativeToGround"
    ) {
      //Just return the ellipsoid referenced property until we support MSL
      return properties;
    }

    if (
      (defined(altitudeMode) && altitudeMode !== "clampToGround") || //
      (defined(gxAltitudeMode) && gxAltitudeMode !== "clampToSeaFloor")
    ) {
      oneTimeWarning(
        "kml-altitudeMode-unknown",
        "KML - Unknown altitudeMode: " +
          defaultValue(altitudeMode, gxAltitudeMode)
      );
    }

    // Clamp to ground is the default
    var propertiesLength = properties.length;
    for (var i = 0; i < propertiesLength; i++) {
      var property = properties[i];
      ellipsoid.scaleToGeodeticSurface(property, property);
    }
    return properties;
  }

  function processPositionGraphics(
    dataSource,
    entity,
    styleEntity,
    heightReference
  ) {
    var label = entity.label;
    if (!defined(label)) {
      label = defined(styleEntity.label)
        ? styleEntity.label.clone()
        : createDefaultLabel();
      entity.label = label;
    }
    label.text = entity.name;

    var billboard = entity.billboard;
    if (!defined(billboard)) {
      billboard = defined(styleEntity.billboard)
        ? styleEntity.billboard.clone()
        : createDefaultBillboard();
      entity.billboard = billboard;
    }

    if (!defined(billboard.image)) {
      billboard.image = dataSource._pinBuilder.fromColor(Color.YELLOW, 64);

      // If there were empty <Icon> tags in the KML, then billboard.image was set to false above
      // However, in this case, the false value would have been converted to a property afterwards
      // Thus, we check if billboard.image is defined with value of false
    } else if (!billboard.image.getValue()) {
      billboard.image = undefined;
    }

    var scale = 1.0;
    if (defined(billboard.scale)) {
      scale = billboard.scale.getValue();
      if (scale !== 0) {
        label.pixelOffset = new Cartesian2(scale * 16 + 1, 0);
      } else {
        //Minor tweaks to better match Google Earth.
        label.pixelOffset = undefined;
        label.horizontalOrigin = undefined;
      }
    }

    if (defined(heightReference) && dataSource._clampToGround) {
      billboard.heightReference = heightReference;
      label.heightReference = heightReference;
    }
  }

  function processPathGraphics(entity, styleEntity) {
    var path = entity.path;
    if (!defined(path)) {
      path = new PathGraphics();
      path.leadTime = 0;
      entity.path = path;
    }

    var polyline = styleEntity.polyline;
    if (defined(polyline)) {
      path.material = polyline.material;
      path.width = polyline.width;
    }
  }

  function processPoint$2(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity
  ) {
    var coordinatesString = queryStringValue(
      geometryNode,
      "coordinates",
      namespaces.kml
    );
    var altitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.kml
    );
    var gxAltitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.gx
    );
    var extrude = queryBooleanValue(geometryNode, "extrude", namespaces.kml);
    var ellipsoid = dataSource._ellipsoid;
    var position = readCoordinate(coordinatesString, ellipsoid);

    entity.position = position;
    processPositionGraphics(
      dataSource,
      entity,
      styleEntity,
      heightReferenceFromAltitudeMode(altitudeMode, gxAltitudeMode)
    );

    if (extrude && isExtrudable(altitudeMode, gxAltitudeMode)) {
      createDropLine(entityCollection, entity, styleEntity);
    }

    return true;
  }

  function processLineStringOrLinearRing(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity
  ) {
    var coordinatesNode = queryFirstNode(
      geometryNode,
      "coordinates",
      namespaces.kml
    );
    var altitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.kml
    );
    var gxAltitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.gx
    );
    var extrude = queryBooleanValue(geometryNode, "extrude", namespaces.kml);
    var tessellate = queryBooleanValue(
      geometryNode,
      "tessellate",
      namespaces.kml
    );
    var canExtrude = isExtrudable(altitudeMode, gxAltitudeMode);
    var zIndex = queryNumericValue(geometryNode, "drawOrder", namespaces.gx);

    var ellipsoid = dataSource._ellipsoid;
    var coordinates = readCoordinates(coordinatesNode, ellipsoid);
    var polyline = styleEntity.polyline;
    if (canExtrude && extrude) {
      var wall = new WallGraphics();
      entity.wall = wall;
      wall.positions = coordinates;
      var polygon = styleEntity.polygon;

      if (defined(polygon)) {
        wall.fill = polygon.fill;
        wall.material = polygon.material;
      }

      //Always outline walls so they show up in 2D.
      wall.outline = true;
      if (defined(polyline)) {
        wall.outlineColor = defined(polyline.material)
          ? polyline.material.color
          : Color.WHITE;
        wall.outlineWidth = polyline.width;
      } else if (defined(polygon)) {
        wall.outlineColor = defined(polygon.material)
          ? polygon.material.color
          : Color.WHITE;
      }
    } else if (dataSource._clampToGround && !canExtrude && tessellate) {
      var polylineGraphics = new PolylineGraphics();
      polylineGraphics.clampToGround = true;
      entity.polyline = polylineGraphics;
      polylineGraphics.positions = coordinates;
      if (defined(polyline)) {
        polylineGraphics.material = defined(polyline.material)
          ? polyline.material.color.getValue(Iso8601.MINIMUM_VALUE)
          : Color.WHITE;
        polylineGraphics.width = defaultValue(polyline.width, 1.0);
      } else {
        polylineGraphics.material = Color.WHITE;
        polylineGraphics.width = 1.0;
      }
      polylineGraphics.zIndex = zIndex;
    } else {
      if (defined(zIndex)) {
        oneTimeWarning(
          "kml-gx:drawOrder",
          "KML - gx:drawOrder is not supported in LineStrings when clampToGround is false"
        );
      }
      if (dataSource._clampToGround && !tessellate) {
        oneTimeWarning(
          "kml-line-tesselate",
          "Ignoring clampToGround for KML lines without the tessellate flag."
        );
      }

      polyline = defined(polyline) ? polyline.clone() : new PolylineGraphics();
      entity.polyline = polyline;
      polyline.positions = createPositionPropertyArrayFromAltitudeMode(
        coordinates,
        altitudeMode,
        gxAltitudeMode,
        ellipsoid
      );
      if (!tessellate || canExtrude) {
        polyline.arcType = ArcType$1.NONE;
      }
    }

    return true;
  }

  function processPolygon$2(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity
  ) {
    var outerBoundaryIsNode = queryFirstNode(
      geometryNode,
      "outerBoundaryIs",
      namespaces.kml
    );
    var linearRingNode = queryFirstNode(
      outerBoundaryIsNode,
      "LinearRing",
      namespaces.kml
    );
    var coordinatesNode = queryFirstNode(
      linearRingNode,
      "coordinates",
      namespaces.kml
    );
    var ellipsoid = dataSource._ellipsoid;
    var coordinates = readCoordinates(coordinatesNode, ellipsoid);
    var extrude = queryBooleanValue(geometryNode, "extrude", namespaces.kml);
    var altitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.kml
    );
    var gxAltitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.gx
    );
    var canExtrude = isExtrudable(altitudeMode, gxAltitudeMode);

    var polygon = defined(styleEntity.polygon)
      ? styleEntity.polygon.clone()
      : createDefaultPolygon();

    var polyline = styleEntity.polyline;
    if (defined(polyline)) {
      polygon.outlineColor = defined(polyline.material)
        ? polyline.material.color
        : Color.WHITE;
      polygon.outlineWidth = polyline.width;
    }
    entity.polygon = polygon;

    if (canExtrude) {
      polygon.perPositionHeight = true;
      polygon.extrudedHeight = extrude ? 0 : undefined;
    } else if (!dataSource._clampToGround) {
      polygon.height = 0;
    }

    if (defined(coordinates)) {
      var hierarchy = new PolygonHierarchy(coordinates);
      var innerBoundaryIsNodes = queryChildNodes(
        geometryNode,
        "innerBoundaryIs",
        namespaces.kml
      );
      for (var j = 0; j < innerBoundaryIsNodes.length; j++) {
        linearRingNode = queryChildNodes(
          innerBoundaryIsNodes[j],
          "LinearRing",
          namespaces.kml
        );
        for (var k = 0; k < linearRingNode.length; k++) {
          coordinatesNode = queryFirstNode(
            linearRingNode[k],
            "coordinates",
            namespaces.kml
          );
          coordinates = readCoordinates(coordinatesNode, ellipsoid);
          if (defined(coordinates)) {
            hierarchy.holes.push(new PolygonHierarchy(coordinates));
          }
        }
      }
      polygon.hierarchy = hierarchy;
    }

    return true;
  }

  function processTrack(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity
  ) {
    var altitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.kml
    );
    var gxAltitudeMode = queryStringValue(
      geometryNode,
      "altitudeMode",
      namespaces.gx
    );
    var coordNodes = queryChildNodes(geometryNode, "coord", namespaces.gx);
    var angleNodes = queryChildNodes(geometryNode, "angles", namespaces.gx);
    var timeNodes = queryChildNodes(geometryNode, "when", namespaces.kml);
    var extrude = queryBooleanValue(geometryNode, "extrude", namespaces.kml);
    var canExtrude = isExtrudable(altitudeMode, gxAltitudeMode);
    var ellipsoid = dataSource._ellipsoid;

    if (angleNodes.length > 0) {
      oneTimeWarning(
        "kml-gx:angles",
        "KML - gx:angles are not supported in gx:Tracks"
      );
    }

    var length = Math.min(coordNodes.length, timeNodes.length);
    var coordinates = [];
    var times = [];
    for (var i = 0; i < length; i++) {
      var position = readCoordinate(coordNodes[i].textContent, ellipsoid);
      coordinates.push(position);
      times.push(JulianDate.fromIso8601(timeNodes[i].textContent));
    }
    var property = new SampledPositionProperty();
    property.addSamples(times, coordinates);
    entity.position = property;
    processPositionGraphics(
      dataSource,
      entity,
      styleEntity,
      heightReferenceFromAltitudeMode(altitudeMode, gxAltitudeMode)
    );
    processPathGraphics(entity, styleEntity);

    entity.availability = new TimeIntervalCollection();

    if (timeNodes.length > 0) {
      entity.availability.addInterval(
        new TimeInterval({
          start: times[0],
          stop: times[times.length - 1],
        })
      );
    }

    if (canExtrude && extrude) {
      createDropLine(entityCollection, entity, styleEntity);
    }

    return true;
  }

  function addToMultiTrack(
    times,
    positions,
    composite,
    availability,
    dropShowProperty,
    extrude,
    altitudeMode,
    gxAltitudeMode,
    includeEndPoints
  ) {
    var start = times[0];
    var stop = times[times.length - 1];

    var data = new SampledPositionProperty();
    data.addSamples(times, positions);

    composite.intervals.addInterval(
      new TimeInterval({
        start: start,
        stop: stop,
        isStartIncluded: includeEndPoints,
        isStopIncluded: includeEndPoints,
        data: createPositionPropertyFromAltitudeMode(
          data,
          altitudeMode,
          gxAltitudeMode
        ),
      })
    );
    availability.addInterval(
      new TimeInterval({
        start: start,
        stop: stop,
        isStartIncluded: includeEndPoints,
        isStopIncluded: includeEndPoints,
      })
    );
    dropShowProperty.intervals.addInterval(
      new TimeInterval({
        start: start,
        stop: stop,
        isStartIncluded: includeEndPoints,
        isStopIncluded: includeEndPoints,
        data: extrude,
      })
    );
  }

  function processMultiTrack(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity
  ) {
    // Multitrack options do not work in GE as detailed in the spec,
    // rather than altitudeMode being at the MultiTrack level,
    // GE just defers all settings to the underlying track.

    var interpolate = queryBooleanValue(
      geometryNode,
      "interpolate",
      namespaces.gx
    );
    var trackNodes = queryChildNodes(geometryNode, "Track", namespaces.gx);

    var times;
    var lastStop;
    var lastStopPosition;
    var needDropLine = false;
    var dropShowProperty = new TimeIntervalCollectionProperty();
    var availability = new TimeIntervalCollection();
    var composite = new CompositePositionProperty();
    var ellipsoid = dataSource._ellipsoid;
    for (var i = 0, len = trackNodes.length; i < len; i++) {
      var trackNode = trackNodes[i];
      var timeNodes = queryChildNodes(trackNode, "when", namespaces.kml);
      var coordNodes = queryChildNodes(trackNode, "coord", namespaces.gx);
      var altitudeMode = queryStringValue(
        trackNode,
        "altitudeMode",
        namespaces.kml
      );
      var gxAltitudeMode = queryStringValue(
        trackNode,
        "altitudeMode",
        namespaces.gx
      );
      var canExtrude = isExtrudable(altitudeMode, gxAltitudeMode);
      var extrude = queryBooleanValue(trackNode, "extrude", namespaces.kml);

      var length = Math.min(coordNodes.length, timeNodes.length);

      var positions = [];
      times = [];
      for (var x = 0; x < length; x++) {
        var position = readCoordinate(coordNodes[x].textContent, ellipsoid);
        positions.push(position);
        times.push(JulianDate.fromIso8601(timeNodes[x].textContent));
      }

      if (interpolate) {
        //If we are interpolating, then we need to fill in the end of
        //the last track and the beginning of this one with a sampled
        //property.  From testing in Google Earth, this property
        //is never extruded and always absolute.
        if (defined(lastStop)) {
          addToMultiTrack(
            [lastStop, times[0]],
            [lastStopPosition, positions[0]],
            composite,
            availability,
            dropShowProperty,
            false,
            "absolute",
            undefined,
            false
          );
        }
        lastStop = times[length - 1];
        lastStopPosition = positions[positions.length - 1];
      }

      addToMultiTrack(
        times,
        positions,
        composite,
        availability,
        dropShowProperty,
        canExtrude && extrude,
        altitudeMode,
        gxAltitudeMode,
        true
      );
      needDropLine = needDropLine || (canExtrude && extrude);
    }

    entity.availability = availability;
    entity.position = composite;
    processPositionGraphics(dataSource, entity, styleEntity);
    processPathGraphics(entity, styleEntity);
    if (needDropLine) {
      createDropLine(entityCollection, entity, styleEntity);
      entity.polyline.show = dropShowProperty;
    }

    return true;
  }

  var geometryTypes$1 = {
    Point: processPoint$2,
    LineString: processLineStringOrLinearRing,
    LinearRing: processLineStringOrLinearRing,
    Polygon: processPolygon$2,
    Track: processTrack,
    MultiTrack: processMultiTrack,
    MultiGeometry: processMultiGeometry,
    Model: processUnsupportedGeometry,
  };

  function processMultiGeometry(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity,
    context
  ) {
    var childNodes = geometryNode.childNodes;
    var hasGeometry = false;
    for (var i = 0, len = childNodes.length; i < len; i++) {
      var childNode = childNodes.item(i);
      var geometryProcessor = geometryTypes$1[childNode.localName];
      if (defined(geometryProcessor)) {
        var childEntity = createEntity(childNode, entityCollection, context);
        childEntity.parent = entity;
        childEntity.name = entity.name;
        childEntity.availability = entity.availability;
        childEntity.description = entity.description;
        childEntity.kml = entity.kml;
        if (
          geometryProcessor(
            dataSource,
            entityCollection,
            childNode,
            childEntity,
            styleEntity
          )
        ) {
          hasGeometry = true;
        }
      }
    }

    return hasGeometry;
  }

  function processUnsupportedGeometry(
    dataSource,
    entityCollection,
    geometryNode,
    entity,
    styleEntity
  ) {
    oneTimeWarning(
      "kml-unsupportedGeometry",
      "KML - Unsupported geometry: " + geometryNode.localName
    );
    return false;
  }

  function processExtendedData(node, entity) {
    var extendedDataNode = queryFirstNode(node, "ExtendedData", namespaces.kml);

    if (!defined(extendedDataNode)) {
      return undefined;
    }

    if (defined(queryFirstNode(extendedDataNode, "SchemaData", namespaces.kml))) {
      oneTimeWarning("kml-schemaData", "KML - SchemaData is unsupported");
    }
    if (defined(queryStringAttribute(extendedDataNode, "xmlns:prefix"))) {
      oneTimeWarning(
        "kml-extendedData",
        "KML - ExtendedData with xmlns:prefix is unsupported"
      );
    }

    var result = {};
    var dataNodes = queryChildNodes(extendedDataNode, "Data", namespaces.kml);
    if (defined(dataNodes)) {
      var length = dataNodes.length;
      for (var i = 0; i < length; i++) {
        var dataNode = dataNodes[i];
        var name = queryStringAttribute(dataNode, "name");
        if (defined(name)) {
          result[name] = {
            displayName: queryStringValue(
              dataNode,
              "displayName",
              namespaces.kml
            ),
            value: queryStringValue(dataNode, "value", namespaces.kml),
          };
        }
      }
    }
    entity.kml.extendedData = result;
  }

  var scratchDiv;
  if (typeof document !== "undefined") {
    scratchDiv = document.createElement("div");
  }

  function processDescription$1(
    node,
    entity,
    styleEntity,
    uriResolver,
    sourceResource
  ) {
    var i;
    var key;
    var keys;

    var kmlData = entity.kml;
    var extendedData = kmlData.extendedData;
    var description = queryStringValue(node, "description", namespaces.kml);

    var balloonStyle = defaultValue(
      entity.balloonStyle,
      styleEntity.balloonStyle
    );

    var background = Color.WHITE;
    var foreground = Color.BLACK;
    var text = description;

    if (defined(balloonStyle)) {
      background = defaultValue(balloonStyle.bgColor, Color.WHITE);
      foreground = defaultValue(balloonStyle.textColor, Color.BLACK);
      text = defaultValue(balloonStyle.text, description);
    }

    var value;
    if (defined(text)) {
      text = text.replace("$[name]", defaultValue(entity.name, ""));
      text = text.replace("$[description]", defaultValue(description, ""));
      text = text.replace("$[address]", defaultValue(kmlData.address, ""));
      text = text.replace("$[Snippet]", defaultValue(kmlData.snippet, ""));
      text = text.replace("$[id]", entity.id);

      //While not explicitly defined by the OGC spec, in Google Earth
      //The appearance of geDirections adds the directions to/from links
      //We simply replace this string with nothing.
      text = text.replace("$[geDirections]", "");

      if (defined(extendedData)) {
        var matches = text.match(/\$\[.+?\]/g);
        if (matches !== null) {
          for (i = 0; i < matches.length; i++) {
            var token = matches[i];
            var propertyName = token.substr(2, token.length - 3);
            var isDisplayName = /\/displayName$/.test(propertyName);
            propertyName = propertyName.replace(/\/displayName$/, "");

            value = extendedData[propertyName];
            if (defined(value)) {
              value = isDisplayName ? value.displayName : value.value;
            }
            if (defined(value)) {
              text = text.replace(token, defaultValue(value, ""));
            }
          }
        }
      }
    } else if (defined(extendedData)) {
      //If no description exists, build a table out of the extended data
      keys = Object.keys(extendedData);
      if (keys.length > 0) {
        text =
          '<table class="cesium-infoBox-defaultTable cesium-infoBox-defaultTable-lighter"><tbody>';
        for (i = 0; i < keys.length; i++) {
          key = keys[i];
          value = extendedData[key];
          text +=
            "<tr><th>" +
            defaultValue(value.displayName, key) +
            "</th><td>" +
            defaultValue(value.value, "") +
            "</td></tr>";
        }
        text += "</tbody></table>";
      }
    }

    if (!defined(text)) {
      //No description
      return;
    }

    //Turns non-explicit links into clickable links.
    text = autolinker.link(text);

    //Use a temporary div to manipulate the links
    //so that they open in a new window.
    scratchDiv.innerHTML = text;
    var links = scratchDiv.querySelectorAll("a");
    for (i = 0; i < links.length; i++) {
      links[i].setAttribute("target", "_blank");
    }

    //Rewrite any KMZ embedded urls
    if (defined(uriResolver) && uriResolver.keys.length > 1) {
      embedDataUris(scratchDiv, "a", "href", uriResolver);
      embedDataUris(scratchDiv, "img", "src", uriResolver);
    }

    //Make relative urls absolute using the sourceResource
    applyBasePath(scratchDiv, "a", "href", sourceResource);
    applyBasePath(scratchDiv, "img", "src", sourceResource);

    var tmp = '<div class="cesium-infoBox-description-lighter" style="';
    tmp += "overflow:auto;";
    tmp += "word-wrap:break-word;";
    tmp += "background-color:" + background.toCssColorString() + ";";
    tmp += "color:" + foreground.toCssColorString() + ";";
    tmp += '">';
    tmp += scratchDiv.innerHTML + "</div>";
    scratchDiv.innerHTML = "";

    //Set the final HTML as the description.
    entity.description = tmp;
  }

  function processFeature$1(dataSource, featureNode, processingData) {
    var entityCollection = processingData.entityCollection;
    var parent = processingData.parentEntity;
    var sourceResource = processingData.sourceResource;
    var uriResolver = processingData.uriResolver;

    var entity = createEntity(
      featureNode,
      entityCollection,
      processingData.context
    );
    var kmlData = entity.kml;
    var styleEntity = computeFinalStyle(
      dataSource,
      featureNode,
      processingData.styleCollection,
      sourceResource,
      uriResolver
    );

    var name = queryStringValue(featureNode, "name", namespaces.kml);
    entity.name = name;
    entity.parent = parent;

    var availability = processTimeSpan(featureNode);
    if (!defined(availability)) {
      availability = processTimeStamp(featureNode);
    }
    entity.availability = availability;

    mergeAvailabilityWithParent(entity);

    // Per KML spec "A Feature is visible only if it and all its ancestors are visible."
    function ancestryIsVisible(parentEntity) {
      if (!parentEntity) {
        return true;
      }
      return parentEntity.show && ancestryIsVisible(parentEntity.parent);
    }

    var visibility = queryBooleanValue(featureNode, "visibility", namespaces.kml);
    entity.show = ancestryIsVisible(parent) && defaultValue(visibility, true);
    //var open = queryBooleanValue(featureNode, 'open', namespaces.kml);

    var authorNode = queryFirstNode(featureNode, "author", namespaces.atom);
    var author = kmlData.author;
    author.name = queryStringValue(authorNode, "name", namespaces.atom);
    author.uri = queryStringValue(authorNode, "uri", namespaces.atom);
    author.email = queryStringValue(authorNode, "email", namespaces.atom);

    var linkNode = queryFirstNode(featureNode, "link", namespaces.atom);
    var link = kmlData.link;
    link.href = queryStringAttribute(linkNode, "href");
    link.hreflang = queryStringAttribute(linkNode, "hreflang");
    link.rel = queryStringAttribute(linkNode, "rel");
    link.type = queryStringAttribute(linkNode, "type");
    link.title = queryStringAttribute(linkNode, "title");
    link.length = queryStringAttribute(linkNode, "length");

    kmlData.address = queryStringValue(featureNode, "address", namespaces.kml);
    kmlData.phoneNumber = queryStringValue(
      featureNode,
      "phoneNumber",
      namespaces.kml
    );
    kmlData.snippet = queryStringValue(featureNode, "Snippet", namespaces.kml);

    processExtendedData(featureNode, entity);
    processDescription$1(
      featureNode,
      entity,
      styleEntity,
      uriResolver,
      sourceResource
    );

    var ellipsoid = dataSource._ellipsoid;
    processLookAt(featureNode, entity, ellipsoid);
    processCamera(featureNode, entity, ellipsoid);

    if (defined(queryFirstNode(featureNode, "Region", namespaces.kml))) {
      oneTimeWarning("kml-region", "KML - Placemark Regions are unsupported");
    }

    return {
      entity: entity,
      styleEntity: styleEntity,
    };
  }

  function processDocument$1(dataSource, node, processingData, deferredLoading) {
    deferredLoading.addNodes(node.childNodes, processingData);
    deferredLoading.process();
  }

  function processFolder(dataSource, node, processingData, deferredLoading) {
    var r = processFeature$1(dataSource, node, processingData);
    var newProcessingData = clone(processingData);
    newProcessingData.parentEntity = r.entity;
    processDocument$1(dataSource, node, newProcessingData, deferredLoading);
  }

  function processPlacemark(
    dataSource,
    placemark,
    processingData,
    deferredLoading
  ) {
    var r = processFeature$1(dataSource, placemark, processingData);
    var entity = r.entity;
    var styleEntity = r.styleEntity;

    var hasGeometry = false;
    var childNodes = placemark.childNodes;
    for (var i = 0, len = childNodes.length; i < len && !hasGeometry; i++) {
      var childNode = childNodes.item(i);
      var geometryProcessor = geometryTypes$1[childNode.localName];
      if (defined(geometryProcessor)) {
        // pass the placemark entity id as a context for case of defining multiple child entities together to handle case
        // where some malformed kmls reuse the same id across placemarks, which works in GE, but is not technically to spec.
        geometryProcessor(
          dataSource,
          processingData.entityCollection,
          childNode,
          entity,
          styleEntity,
          entity.id
        );
        hasGeometry = true;
      }
    }

    if (!hasGeometry) {
      entity.merge(styleEntity);
      processPositionGraphics(dataSource, entity, styleEntity);
    }
  }

  var playlistNodeProcessors = {
    FlyTo: processTourFlyTo,
    Wait: processTourWait,
    SoundCue: processTourUnsupportedNode,
    AnimatedUpdate: processTourUnsupportedNode,
    TourControl: processTourUnsupportedNode,
  };

  function processTour(dataSource, node, processingData, deferredLoading) {
    var name = queryStringValue(node, "name", namespaces.kml);
    var id = queryStringAttribute(node, "id");
    var tour = new KmlTour(name, id);

    var playlistNode = queryFirstNode(node, "Playlist", namespaces.gx);
    if (playlistNode) {
      var ellipsoid = dataSource._ellipsoid;
      var childNodes = playlistNode.childNodes;
      for (var i = 0; i < childNodes.length; i++) {
        var entryNode = childNodes[i];
        if (entryNode.localName) {
          var playlistNodeProcessor = playlistNodeProcessors[entryNode.localName];
          if (playlistNodeProcessor) {
            playlistNodeProcessor(tour, entryNode, ellipsoid);
          } else {
            console.log(
              "Unknown KML Tour playlist entry type " + entryNode.localName
            );
          }
        }
      }
    }

    if (!defined(dataSource.kmlTours)) {
      dataSource.kmlTours = [];
    }

    dataSource.kmlTours.push(tour);
  }

  function processTourUnsupportedNode(tour, entryNode) {
    oneTimeWarning("KML Tour unsupported node " + entryNode.localName);
  }

  function processTourWait(tour, entryNode) {
    var duration = queryNumericValue(entryNode, "duration", namespaces.gx);
    tour.addPlaylistEntry(new KmlTourWait(duration));
  }

  function processTourFlyTo(tour, entryNode, ellipsoid) {
    var duration = queryNumericValue(entryNode, "duration", namespaces.gx);
    var flyToMode = queryStringValue(entryNode, "flyToMode", namespaces.gx);

    var t = { kml: {} };

    processLookAt(entryNode, t, ellipsoid);
    processCamera(entryNode, t, ellipsoid);

    var view = t.kml.lookAt || t.kml.camera;

    var flyto = new KmlTourFlyTo(duration, flyToMode, view);
    tour.addPlaylistEntry(flyto);
  }

  function processCamera(featureNode, entity, ellipsoid) {
    var camera = queryFirstNode(featureNode, "Camera", namespaces.kml);
    if (defined(camera)) {
      var lon = defaultValue(
        queryNumericValue(camera, "longitude", namespaces.kml),
        0.0
      );
      var lat = defaultValue(
        queryNumericValue(camera, "latitude", namespaces.kml),
        0.0
      );
      var altitude = defaultValue(
        queryNumericValue(camera, "altitude", namespaces.kml),
        0.0
      );

      var heading = defaultValue(
        queryNumericValue(camera, "heading", namespaces.kml),
        0.0
      );
      var tilt = defaultValue(
        queryNumericValue(camera, "tilt", namespaces.kml),
        0.0
      );
      var roll = defaultValue(
        queryNumericValue(camera, "roll", namespaces.kml),
        0.0
      );

      var position = Cartesian3.fromDegrees(lon, lat, altitude, ellipsoid);
      var hpr = HeadingPitchRoll.fromDegrees(heading, tilt - 90.0, roll);

      entity.kml.camera = new KmlCamera(position, hpr);
    }
  }

  function processLookAt(featureNode, entity, ellipsoid) {
    var lookAt = queryFirstNode(featureNode, "LookAt", namespaces.kml);
    if (defined(lookAt)) {
      var lon = defaultValue(
        queryNumericValue(lookAt, "longitude", namespaces.kml),
        0.0
      );
      var lat = defaultValue(
        queryNumericValue(lookAt, "latitude", namespaces.kml),
        0.0
      );
      var altitude = defaultValue(
        queryNumericValue(lookAt, "altitude", namespaces.kml),
        0.0
      );
      var heading = queryNumericValue(lookAt, "heading", namespaces.kml);
      var tilt = queryNumericValue(lookAt, "tilt", namespaces.kml);
      var range = defaultValue(
        queryNumericValue(lookAt, "range", namespaces.kml),
        0.0
      );

      tilt = CesiumMath.toRadians(defaultValue(tilt, 0.0));
      heading = CesiumMath.toRadians(defaultValue(heading, 0.0));

      var hpr = new HeadingPitchRange(
        heading,
        tilt - CesiumMath.PI_OVER_TWO,
        range
      );
      var viewPoint = Cartesian3.fromDegrees(lon, lat, altitude, ellipsoid);

      entity.kml.lookAt = new KmlLookAt(viewPoint, hpr);
    }
  }

  function processGroundOverlay(
    dataSource,
    groundOverlay,
    processingData,
    deferredLoading
  ) {
    var r = processFeature$1(dataSource, groundOverlay, processingData);
    var entity = r.entity;

    var geometry;
    var isLatLonQuad = false;

    var ellipsoid = dataSource._ellipsoid;
    var positions = readCoordinates(
      queryFirstNode(groundOverlay, "LatLonQuad", namespaces.gx),
      ellipsoid
    );
    var zIndex = queryNumericValue(groundOverlay, "drawOrder", namespaces.kml);
    if (defined(positions)) {
      geometry = createDefaultPolygon();
      geometry.hierarchy = new PolygonHierarchy(positions);
      geometry.zIndex = zIndex;
      entity.polygon = geometry;
      isLatLonQuad = true;
    } else {
      geometry = new RectangleGraphics();
      geometry.zIndex = zIndex;
      entity.rectangle = geometry;

      var latLonBox = queryFirstNode(groundOverlay, "LatLonBox", namespaces.kml);
      if (defined(latLonBox)) {
        var west = queryNumericValue(latLonBox, "west", namespaces.kml);
        var south = queryNumericValue(latLonBox, "south", namespaces.kml);
        var east = queryNumericValue(latLonBox, "east", namespaces.kml);
        var north = queryNumericValue(latLonBox, "north", namespaces.kml);

        if (defined(west)) {
          west = CesiumMath.negativePiToPi(CesiumMath.toRadians(west));
        }
        if (defined(south)) {
          south = CesiumMath.clampToLatitudeRange(CesiumMath.toRadians(south));
        }
        if (defined(east)) {
          east = CesiumMath.negativePiToPi(CesiumMath.toRadians(east));
        }
        if (defined(north)) {
          north = CesiumMath.clampToLatitudeRange(CesiumMath.toRadians(north));
        }
        geometry.coordinates = new Rectangle(west, south, east, north);

        var rotation = queryNumericValue(latLonBox, "rotation", namespaces.kml);
        if (defined(rotation)) {
          var rotationRadians = CesiumMath.toRadians(rotation);
          geometry.rotation = rotationRadians;
          geometry.stRotation = rotationRadians;
        }
      }
    }

    var iconNode = queryFirstNode(groundOverlay, "Icon", namespaces.kml);
    var href = getIconHref(
      iconNode,
      dataSource,
      processingData.sourceResource,
      processingData.uriResolver,
      true
    );
    if (defined(href)) {
      if (isLatLonQuad) {
        oneTimeWarning(
          "kml-gx:LatLonQuad",
          "KML - gx:LatLonQuad Icon does not support texture projection."
        );
      }
      var x = queryNumericValue(iconNode, "x", namespaces.gx);
      var y = queryNumericValue(iconNode, "y", namespaces.gx);
      var w = queryNumericValue(iconNode, "w", namespaces.gx);
      var h = queryNumericValue(iconNode, "h", namespaces.gx);

      if (defined(x) || defined(y) || defined(w) || defined(h)) {
        oneTimeWarning(
          "kml-groundOverlay-xywh",
          "KML - gx:x, gx:y, gx:w, gx:h aren't supported for GroundOverlays"
        );
      }

      geometry.material = href;
      geometry.material.color = queryColorValue(
        groundOverlay,
        "color",
        namespaces.kml
      );
      geometry.material.transparent = true;
    } else {
      geometry.material = queryColorValue(groundOverlay, "color", namespaces.kml);
    }

    var altitudeMode = queryStringValue(
      groundOverlay,
      "altitudeMode",
      namespaces.kml
    );

    if (defined(altitudeMode)) {
      if (altitudeMode === "absolute") {
        //Use height above ellipsoid until we support MSL.
        geometry.height = queryNumericValue(
          groundOverlay,
          "altitude",
          namespaces.kml
        );
        geometry.zIndex = undefined;
      } else if (altitudeMode !== "clampToGround") {
        oneTimeWarning(
          "kml-altitudeMode-unknown",
          "KML - Unknown altitudeMode: " + altitudeMode
        );
      }
      // else just use the default of 0 until we support 'clampToGround'
    } else {
      altitudeMode = queryStringValue(
        groundOverlay,
        "altitudeMode",
        namespaces.gx
      );
      if (altitudeMode === "relativeToSeaFloor") {
        oneTimeWarning(
          "kml-altitudeMode-relativeToSeaFloor",
          "KML - altitudeMode relativeToSeaFloor is currently not supported, treating as absolute."
        );
        geometry.height = queryNumericValue(
          groundOverlay,
          "altitude",
          namespaces.kml
        );
        geometry.zIndex = undefined;
      } else if (altitudeMode === "clampToSeaFloor") {
        oneTimeWarning(
          "kml-altitudeMode-clampToSeaFloor",
          "KML - altitudeMode clampToSeaFloor is currently not supported, treating as clampToGround."
        );
      } else if (defined(altitudeMode)) {
        oneTimeWarning(
          "kml-altitudeMode-unknown",
          "KML - Unknown altitudeMode: " + altitudeMode
        );
      }
    }
  }

  function processUnsupportedFeature(
    dataSource,
    node,
    processingData,
    deferredLoading
  ) {
    dataSource._unsupportedNode.raiseEvent(
      dataSource,
      processingData.parentEntity,
      node,
      processingData.entityCollection,
      processingData.styleCollection,
      processingData.sourceResource,
      processingData.uriResolver
    );
    oneTimeWarning(
      "kml-unsupportedFeature-" + node.nodeName,
      "KML - Unsupported feature: " + node.nodeName
    );
  }

  var RefreshMode = {
    INTERVAL: 0,
    EXPIRE: 1,
    STOP: 2,
  };

  function cleanupString(s) {
    if (!defined(s) || s.length === 0) {
      return "";
    }

    var sFirst = s[0];
    if (sFirst === "&" || sFirst === "?") {
      s = s.substring(1);
    }

    return s;
  }

  var zeroRectangle = new Rectangle();
  var scratchCartographic$9 = new Cartographic();
  var scratchCartesian2$9 = new Cartesian2();
  var scratchCartesian3$a = new Cartesian3();

  function processNetworkLinkQueryString(
    resource,
    camera,
    canvas,
    viewBoundScale,
    bbox,
    ellipsoid
  ) {
    function fixLatitude(value) {
      if (value < -CesiumMath.PI_OVER_TWO) {
        return -CesiumMath.PI_OVER_TWO;
      } else if (value > CesiumMath.PI_OVER_TWO) {
        return CesiumMath.PI_OVER_TWO;
      }
      return value;
    }

    function fixLongitude(value) {
      if (value > CesiumMath.PI) {
        return value - CesiumMath.TWO_PI;
      } else if (value < -CesiumMath.PI) {
        return value + CesiumMath.TWO_PI;
      }

      return value;
    }

    var queryString = objectToQuery(resource.queryParameters);

    // objectToQuery escapes [ and ], so fix that
    queryString = queryString.replace(/%5B/g, "[").replace(/%5D/g, "]");

    if (defined(camera) && camera._mode !== SceneMode$1.MORPHING) {
      var centerCartesian;
      var centerCartographic;

      bbox = defaultValue(bbox, zeroRectangle);
      if (defined(canvas)) {
        scratchCartesian2$9.x = canvas.clientWidth * 0.5;
        scratchCartesian2$9.y = canvas.clientHeight * 0.5;
        centerCartesian = camera.pickEllipsoid(
          scratchCartesian2$9,
          ellipsoid,
          scratchCartesian3$a
        );
      }

      if (defined(centerCartesian)) {
        centerCartographic = ellipsoid.cartesianToCartographic(
          centerCartesian,
          scratchCartographic$9
        );
      } else {
        centerCartographic = Rectangle.center(bbox, scratchCartographic$9);
        centerCartesian = ellipsoid.cartographicToCartesian(centerCartographic);
      }

      if (
        defined(viewBoundScale) &&
        !CesiumMath.equalsEpsilon(viewBoundScale, 1.0, CesiumMath.EPSILON9)
      ) {
        var newHalfWidth = bbox.width * viewBoundScale * 0.5;
        var newHalfHeight = bbox.height * viewBoundScale * 0.5;
        bbox = new Rectangle(
          fixLongitude(centerCartographic.longitude - newHalfWidth),
          fixLatitude(centerCartographic.latitude - newHalfHeight),
          fixLongitude(centerCartographic.longitude + newHalfWidth),
          fixLatitude(centerCartographic.latitude + newHalfHeight)
        );
      }

      queryString = queryString.replace(
        "[bboxWest]",
        CesiumMath.toDegrees(bbox.west).toString()
      );
      queryString = queryString.replace(
        "[bboxSouth]",
        CesiumMath.toDegrees(bbox.south).toString()
      );
      queryString = queryString.replace(
        "[bboxEast]",
        CesiumMath.toDegrees(bbox.east).toString()
      );
      queryString = queryString.replace(
        "[bboxNorth]",
        CesiumMath.toDegrees(bbox.north).toString()
      );

      var lon = CesiumMath.toDegrees(centerCartographic.longitude).toString();
      var lat = CesiumMath.toDegrees(centerCartographic.latitude).toString();
      queryString = queryString.replace("[lookatLon]", lon);
      queryString = queryString.replace("[lookatLat]", lat);
      queryString = queryString.replace(
        "[lookatTilt]",
        CesiumMath.toDegrees(camera.pitch).toString()
      );
      queryString = queryString.replace(
        "[lookatHeading]",
        CesiumMath.toDegrees(camera.heading).toString()
      );
      queryString = queryString.replace(
        "[lookatRange]",
        Cartesian3.distance(camera.positionWC, centerCartesian)
      );
      queryString = queryString.replace("[lookatTerrainLon]", lon);
      queryString = queryString.replace("[lookatTerrainLat]", lat);
      queryString = queryString.replace(
        "[lookatTerrainAlt]",
        centerCartographic.height.toString()
      );

      ellipsoid.cartesianToCartographic(camera.positionWC, scratchCartographic$9);
      queryString = queryString.replace(
        "[cameraLon]",
        CesiumMath.toDegrees(scratchCartographic$9.longitude).toString()
      );
      queryString = queryString.replace(
        "[cameraLat]",
        CesiumMath.toDegrees(scratchCartographic$9.latitude).toString()
      );
      queryString = queryString.replace(
        "[cameraAlt]",
        CesiumMath.toDegrees(scratchCartographic$9.height).toString()
      );

      var frustum = camera.frustum;
      var aspectRatio = frustum.aspectRatio;
      var horizFov = "";
      var vertFov = "";
      if (defined(aspectRatio)) {
        var fov = CesiumMath.toDegrees(frustum.fov);
        if (aspectRatio > 1.0) {
          horizFov = fov;
          vertFov = fov / aspectRatio;
        } else {
          vertFov = fov;
          horizFov = fov * aspectRatio;
        }
      }
      queryString = queryString.replace("[horizFov]", horizFov.toString());
      queryString = queryString.replace("[vertFov]", vertFov.toString());
    } else {
      queryString = queryString.replace("[bboxWest]", "-180");
      queryString = queryString.replace("[bboxSouth]", "-90");
      queryString = queryString.replace("[bboxEast]", "180");
      queryString = queryString.replace("[bboxNorth]", "90");

      queryString = queryString.replace("[lookatLon]", "");
      queryString = queryString.replace("[lookatLat]", "");
      queryString = queryString.replace("[lookatRange]", "");
      queryString = queryString.replace("[lookatTilt]", "");
      queryString = queryString.replace("[lookatHeading]", "");
      queryString = queryString.replace("[lookatTerrainLon]", "");
      queryString = queryString.replace("[lookatTerrainLat]", "");
      queryString = queryString.replace("[lookatTerrainAlt]", "");

      queryString = queryString.replace("[cameraLon]", "");
      queryString = queryString.replace("[cameraLat]", "");
      queryString = queryString.replace("[cameraAlt]", "");
      queryString = queryString.replace("[horizFov]", "");
      queryString = queryString.replace("[vertFov]", "");
    }

    if (defined(canvas)) {
      queryString = queryString.replace("[horizPixels]", canvas.clientWidth);
      queryString = queryString.replace("[vertPixels]", canvas.clientHeight);
    } else {
      queryString = queryString.replace("[horizPixels]", "");
      queryString = queryString.replace("[vertPixels]", "");
    }

    queryString = queryString.replace("[terrainEnabled]", "1");
    queryString = queryString.replace("[clientVersion]", "1");
    queryString = queryString.replace("[kmlVersion]", "2.2");
    queryString = queryString.replace("[clientName]", "Cesium");
    queryString = queryString.replace("[language]", "English");

    resource.setQueryParameters(queryToObject(queryString));
  }

  function processNetworkLink(dataSource, node, processingData, deferredLoading) {
    var r = processFeature$1(dataSource, node, processingData);
    var networkEntity = r.entity;

    var sourceResource = processingData.sourceResource;
    var uriResolver = processingData.uriResolver;

    var link = queryFirstNode(node, "Link", namespaces.kml);

    if (!defined(link)) {
      link = queryFirstNode(node, "Url", namespaces.kml);
    }
    if (defined(link)) {
      var href = queryStringValue(link, "href", namespaces.kml);
      var viewRefreshMode;
      var viewBoundScale;
      if (defined(href)) {
        var newSourceUri = href;
        href = resolveHref(href, sourceResource, processingData.uriResolver);

        // We need to pass in the original path if resolveHref returns a data uri because the network link
        //  references a document in a KMZ archive
        if (/^data:/.test(href.getUrlComponent())) {
          // So if sourceUri isn't the kmz file, then its another kml in the archive, so resolve it
          if (!/\.kmz/i.test(sourceResource.getUrlComponent())) {
            newSourceUri = sourceResource.getDerivedResource({
              url: newSourceUri,
            });
          }
        } else {
          newSourceUri = href.clone(); // Not a data uri so use the fully qualified uri
          viewRefreshMode = queryStringValue(
            link,
            "viewRefreshMode",
            namespaces.kml
          );
          viewBoundScale = defaultValue(
            queryStringValue(link, "viewBoundScale", namespaces.kml),
            1.0
          );
          var defaultViewFormat =
            viewRefreshMode === "onStop"
              ? "BBOX=[bboxWest],[bboxSouth],[bboxEast],[bboxNorth]"
              : "";
          var viewFormat = defaultValue(
            queryStringValue(link, "viewFormat", namespaces.kml),
            defaultViewFormat
          );
          var httpQuery = queryStringValue(link, "httpQuery", namespaces.kml);
          if (defined(viewFormat)) {
            href.setQueryParameters(queryToObject(cleanupString(viewFormat)));
          }
          if (defined(httpQuery)) {
            href.setQueryParameters(queryToObject(cleanupString(httpQuery)));
          }

          var ellipsoid = dataSource._ellipsoid;
          processNetworkLinkQueryString(
            href,
            dataSource._camera,
            dataSource._canvas,
            viewBoundScale,
            dataSource._lastCameraView.bbox,
            ellipsoid
          );
        }

        var options = {
          sourceUri: newSourceUri,
          uriResolver: uriResolver,
          context: networkEntity.id,
        };
        var networkLinkCollection = new EntityCollection();
        var promise = load$2(dataSource, networkLinkCollection, href, options)
          .then(function (rootElement) {
            var entities = dataSource._entityCollection;
            var newEntities = networkLinkCollection.values;
            entities.suspendEvents();
            for (var i = 0; i < newEntities.length; i++) {
              var newEntity = newEntities[i];
              if (!defined(newEntity.parent)) {
                newEntity.parent = networkEntity;
                mergeAvailabilityWithParent(newEntity);
              }

              entities.add(newEntity);
            }
            entities.resumeEvents();

            // Add network links to a list if we need they will need to be updated
            var refreshMode = queryStringValue(
              link,
              "refreshMode",
              namespaces.kml
            );
            var refreshInterval = defaultValue(
              queryNumericValue(link, "refreshInterval", namespaces.kml),
              0
            );
            if (
              (refreshMode === "onInterval" && refreshInterval > 0) ||
              refreshMode === "onExpire" ||
              viewRefreshMode === "onStop"
            ) {
              var networkLinkControl = queryFirstNode(
                rootElement,
                "NetworkLinkControl",
                namespaces.kml
              );
              var hasNetworkLinkControl = defined(networkLinkControl);

              var now = JulianDate.now();
              var networkLinkInfo = {
                id: createGuid(),
                href: href,
                cookie: {},
                lastUpdated: now,
                updating: false,
                entity: networkEntity,
                viewBoundScale: viewBoundScale,
                needsUpdate: false,
                cameraUpdateTime: now,
              };

              var minRefreshPeriod = 0;
              if (hasNetworkLinkControl) {
                networkLinkInfo.cookie = queryToObject(
                  defaultValue(
                    queryStringValue(
                      networkLinkControl,
                      "cookie",
                      namespaces.kml
                    ),
                    ""
                  )
                );
                minRefreshPeriod = defaultValue(
                  queryNumericValue(
                    networkLinkControl,
                    "minRefreshPeriod",
                    namespaces.kml
                  ),
                  0
                );
              }

              if (refreshMode === "onInterval") {
                if (hasNetworkLinkControl) {
                  refreshInterval = Math.max(minRefreshPeriod, refreshInterval);
                }
                networkLinkInfo.refreshMode = RefreshMode.INTERVAL;
                networkLinkInfo.time = refreshInterval;
              } else if (refreshMode === "onExpire") {
                var expires;
                if (hasNetworkLinkControl) {
                  expires = queryStringValue(
                    networkLinkControl,
                    "expires",
                    namespaces.kml
                  );
                }
                if (defined(expires)) {
                  try {
                    var date = JulianDate.fromIso8601(expires);
                    var diff = JulianDate.secondsDifference(date, now);
                    if (diff > 0 && diff < minRefreshPeriod) {
                      JulianDate.addSeconds(now, minRefreshPeriod, date);
                    }
                    networkLinkInfo.refreshMode = RefreshMode.EXPIRE;
                    networkLinkInfo.time = date;
                  } catch (e) {
                    oneTimeWarning(
                      "kml-refreshMode-onInterval-onExpire",
                      "KML - NetworkLinkControl expires is not a valid date"
                    );
                  }
                } else {
                  oneTimeWarning(
                    "kml-refreshMode-onExpire",
                    "KML - refreshMode of onExpire requires the NetworkLinkControl to have an expires element"
                  );
                }
              } else if (dataSource._camera) {
                // Only allow onStop refreshes if we have a camera
                networkLinkInfo.refreshMode = RefreshMode.STOP;
                networkLinkInfo.time = defaultValue(
                  queryNumericValue(link, "viewRefreshTime", namespaces.kml),
                  0
                );
              } else {
                oneTimeWarning(
                  "kml-refrehMode-onStop-noCamera",
                  "A NetworkLink with viewRefreshMode=onStop requires a camera be passed in when creating the KmlDataSource"
                );
              }

              if (defined(networkLinkInfo.refreshMode)) {
                dataSource._networkLinks.set(networkLinkInfo.id, networkLinkInfo);
              }
            } else if (viewRefreshMode === "onRegion") {
              oneTimeWarning(
                "kml-refrehMode-onRegion",
                "KML - Unsupported viewRefreshMode: onRegion"
              );
            }
          })
          .otherwise(function (error) {
            oneTimeWarning("An error occured during loading " + href.url);
            dataSource._error.raiseEvent(dataSource, error);
          });

        deferredLoading.addPromise(promise);
      }
    }
  }

  function processFeatureNode(dataSource, node, processingData, deferredLoading) {
    var featureProcessor = featureTypes[node.localName];
    if (defined(featureProcessor)) {
      return featureProcessor(dataSource, node, processingData, deferredLoading);
    }

    return processUnsupportedFeature(
      dataSource,
      node,
      processingData);
  }

  function loadKml(
    dataSource,
    entityCollection,
    kml,
    sourceResource,
    uriResolver,
    context
  ) {
    entityCollection.removeAll();

    var documentElement = kml.documentElement;
    var document =
      documentElement.localName === "Document"
        ? documentElement
        : queryFirstNode(documentElement, "Document", namespaces.kml);
    var name = queryStringValue(document, "name", namespaces.kml);
    if (!defined(name)) {
      name = getFilenameFromUri(sourceResource.getUrlComponent());
    }

    // Only set the name from the root document
    if (!defined(dataSource._name)) {
      dataSource._name = name;
    }

    var deferredLoading = new KmlDataSource._DeferredLoading(dataSource);
    var styleCollection = new EntityCollection(dataSource);
    return when
      .all(
        processStyles(
          dataSource,
          kml,
          styleCollection,
          sourceResource,
          false,
          uriResolver
        )
      )
      .then(function () {
        var element = kml.documentElement;
        if (element.localName === "kml") {
          var childNodes = element.childNodes;
          for (var i = 0; i < childNodes.length; i++) {
            var tmp = childNodes[i];
            if (defined(featureTypes[tmp.localName])) {
              element = tmp;
              break;
            }
          }
        }

        var processingData = {
          parentEntity: undefined,
          entityCollection: entityCollection,
          styleCollection: styleCollection,
          sourceResource: sourceResource,
          uriResolver: uriResolver,
          context: context,
        };

        entityCollection.suspendEvents();
        processFeatureNode(dataSource, element, processingData, deferredLoading);
        entityCollection.resumeEvents();

        return deferredLoading.wait().then(function () {
          return kml.documentElement;
        });
      });
  }

  function loadKmz(dataSource, entityCollection, blob, sourceResource) {
    var deferred = when.defer();
    zip.createReader(
      new zip.BlobReader(blob),
      function (reader) {
        reader.getEntries(function (entries) {
          var promises = [];
          var uriResolver = {};
          var docEntry;
          var docDefer;
          for (var i = 0; i < entries.length; i++) {
            var entry = entries[i];
            if (!entry.directory) {
              var innerDefer = when.defer();
              promises.push(innerDefer.promise);
              if (/\.kml$/i.test(entry.filename)) {
                // We use the first KML document we come across
                //  https://developers.google.com/kml/documentation/kmzarchives
                // Unless we come across a .kml file at the root of the archive because GE does this
                if (!defined(docEntry) || !/\//i.test(entry.filename)) {
                  if (defined(docEntry)) {
                    // We found one at the root so load the initial kml as a data uri
                    loadDataUriFromZip(docEntry, uriResolver, docDefer);
                  }
                  docEntry = entry;
                  docDefer = innerDefer;
                } else {
                  // Wasn't the first kml and wasn't at the root
                  loadDataUriFromZip(entry, uriResolver, innerDefer);
                }
              } else {
                loadDataUriFromZip(entry, uriResolver, innerDefer);
              }
            }
          }

          // Now load the root KML document
          if (defined(docEntry)) {
            loadXmlFromZip(docEntry, uriResolver, docDefer);
          }
          when
            .all(promises)
            .then(function () {
              reader.close();
              if (!defined(uriResolver.kml)) {
                deferred.reject(
                  new RuntimeError("KMZ file does not contain a KML document.")
                );
                return;
              }
              uriResolver.keys = Object.keys(uriResolver);
              return loadKml(
                dataSource,
                entityCollection,
                uriResolver.kml,
                sourceResource,
                uriResolver
              );
            })
            .then(deferred.resolve)
            .otherwise(deferred.reject);
        });
      },
      function (e) {
        deferred.reject(e);
      }
    );

    return deferred.promise;
  }

  function load$2(dataSource, entityCollection, data, options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var sourceUri = options.sourceUri;
    var uriResolver = options.uriResolver;
    var context = options.context;

    var promise = data;
    if (typeof data === "string" || data instanceof Resource) {
      data = Resource.createIfNeeded(data);
      promise = data.fetchBlob();
      sourceUri = defaultValue(sourceUri, data.clone());

      // Add resource credits to our list of credits to display
      var resourceCredits = dataSource._resourceCredits;
      var credits = data.credits;
      if (defined(credits)) {
        var length = credits.length;
        for (var i = 0; i < length; i++) {
          resourceCredits.push(credits[i]);
        }
      }
    } else {
      sourceUri = defaultValue(sourceUri, Resource.DEFAULT.clone());
    }

    sourceUri = Resource.createIfNeeded(sourceUri);

    return when(promise)
      .then(function (dataToLoad) {
        if (dataToLoad instanceof Blob) {
          return isZipFile(dataToLoad).then(function (isZip) {
            if (isZip) {
              return loadKmz(dataSource, entityCollection, dataToLoad, sourceUri);
            }
            return readBlobAsText(dataToLoad).then(function (text) {
              //There's no official way to validate if a parse was successful.
              //The following check detects the error on various browsers.

              //Insert missing namespaces
              text = insertNamespaces(text);

              //Remove Duplicate Namespaces
              text = removeDuplicateNamespaces(text);

              //IE raises an exception
              var kml;
              var error;
              try {
                kml = parser.parseFromString(text, "application/xml");
              } catch (e) {
                error = e.toString();
              }

              //The parse succeeds on Chrome and Firefox, but the error
              //handling is different in each.
              if (
                defined(error) ||
                kml.body ||
                kml.documentElement.tagName === "parsererror"
              ) {
                //Firefox has error information as the firstChild nodeValue.
                var msg = defined(error)
                  ? error
                  : kml.documentElement.firstChild.nodeValue;

                //Chrome has it in the body text.
                if (!msg) {
                  msg = kml.body.innerText;
                }

                //Return the error
                throw new RuntimeError(msg);
              }
              return loadKml(
                dataSource,
                entityCollection,
                kml,
                sourceUri,
                uriResolver,
                context
              );
            });
          });
        }
        return loadKml(
          dataSource,
          entityCollection,
          dataToLoad,
          sourceUri,
          uriResolver,
          context
        );
      })
      .otherwise(function (error) {
        dataSource._error.raiseEvent(dataSource, error);
        console.log(error);
        return when.reject(error);
      });
  }

  /**
   * @typedef {Object} KmlDataSource.LoadOptions
   *
   * Initialization options for the `load` method.
   *
   * @property {Camera} camera The camera that is used for viewRefreshModes and sending camera properties to network links.
   * @property {HTMLCanvasElement} canvas The canvas that is used for sending viewer properties to network links.
   * @property {String} [sourceUri] Overrides the url to use for resolving relative links and other KML network features.
   * @property {Boolean} [clampToGround=false] true if we want the geometry features (Polygons, LineStrings and LinearRings) clamped to the ground.
   * @property {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The global ellipsoid used for geographical calculations.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * A {@link DataSource} which processes Keyhole Markup Language 2.2 (KML).
   * <p>
   * KML support in Cesium is incomplete, but a large amount of the standard,
   * as well as Google's <code>gx</code> extension namespace, is supported. See Github issue
   * {@link https://github.com/CesiumGS/cesium/issues/873|#873} for a
   * detailed list of what is and isn't support. Cesium will also write information to the
   * console when it encounters most unsupported features.
   * </p>
   * <p>
   * Non visual feature data, such as <code>atom:author</code> and <code>ExtendedData</code>
   * is exposed via an instance of {@link KmlFeatureData}, which is added to each {@link Entity}
   * under the <code>kml</code> property.
   * </p>
   *
   * @alias KmlDataSource
   * @constructor
   *
   * @param {Object} options An object with the following properties:
   * @param {Camera} options.camera The camera that is used for viewRefreshModes and sending camera properties to network links.
   * @param {HTMLCanvasElement} options.canvas The canvas that is used for sending viewer properties to network links.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The global ellipsoid used for geographical calculations.
   * @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
   *
   * @see {@link http://www.opengeospatial.org/standards/kml/|Open Geospatial Consortium KML Standard}
   * @see {@link https://developers.google.com/kml/|Google KML Documentation}
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=KML.html|Cesium Sandcastle KML Demo}
   *
   * @example
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.dataSources.add(Cesium.KmlDataSource.load('../../SampleData/facilities.kmz',
   *      {
   *           camera: viewer.scene.camera,
   *           canvas: viewer.scene.canvas
   *      })
   * );
   */
  function KmlDataSource(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var camera = options.camera;
    var canvas = options.canvas;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(camera)) {
      throw new DeveloperError("options.camera is required.");
    }
    if (!defined(canvas)) {
      throw new DeveloperError("options.canvas is required.");
    }
    //>>includeEnd('debug');

    this._changed = new Event();
    this._error = new Event();
    this._loading = new Event();
    this._refresh = new Event();
    this._unsupportedNode = new Event();

    this._clock = undefined;
    this._entityCollection = new EntityCollection(this);
    this._name = undefined;
    this._isLoading = false;
    this._pinBuilder = new PinBuilder();
    this._networkLinks = new AssociativeArray();
    this._entityCluster = new EntityCluster();

    this._canvas = canvas;
    this._camera = camera;
    this._lastCameraView = {
      position: defined(camera) ? Cartesian3.clone(camera.positionWC) : undefined,
      direction: defined(camera)
        ? Cartesian3.clone(camera.directionWC)
        : undefined,
      up: defined(camera) ? Cartesian3.clone(camera.upWC) : undefined,
      bbox: defined(camera)
        ? camera.computeViewRectangle()
        : Rectangle.clone(Rectangle.MAX_VALUE),
    };

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.WGS84);

    // User specified credit
    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    // Create a list of Credit's from the resource that the user can't remove
    this._resourceCredits = [];
  }

  /**
   * Creates a Promise to a new instance loaded with the provided KML data.
   *
   * @param {Resource|String|Document|Blob} data A url, parsed KML document, or Blob containing binary KMZ data or a parsed KML document.
   * @param {KmlDataSource.LoadOptions} [options] An object specifying configuration options
   *
   * @returns {Promise.<KmlDataSource>} A promise that will resolve to a new KmlDataSource instance once the KML is loaded.
   */
  KmlDataSource.load = function (data, options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var dataSource = new KmlDataSource(options);
    return dataSource.load(data, options);
  };

  Object.defineProperties(KmlDataSource.prototype, {
    /**
     * Gets or sets a human-readable name for this instance.
     * This will be automatically be set to the KML document name on load.
     * @memberof KmlDataSource.prototype
     * @type {String}
     */
    name: {
      get: function () {
        return this._name;
      },
      set: function (value) {
        if (this._name !== value) {
          this._name = value;
          this._changed.raiseEvent(this);
        }
      },
    },
    /**
     * Gets the clock settings defined by the loaded KML. This represents the total
     * availability interval for all time-dynamic data. If the KML does not contain
     * time-dynamic data, this value is undefined.
     * @memberof KmlDataSource.prototype
     * @type {DataSourceClock}
     */
    clock: {
      get: function () {
        return this._clock;
      },
    },
    /**
     * Gets the collection of {@link Entity} instances.
     * @memberof KmlDataSource.prototype
     * @type {EntityCollection}
     */
    entities: {
      get: function () {
        return this._entityCollection;
      },
    },
    /**
     * Gets a value indicating if the data source is currently loading data.
     * @memberof KmlDataSource.prototype
     * @type {Boolean}
     */
    isLoading: {
      get: function () {
        return this._isLoading;
      },
    },
    /**
     * Gets an event that will be raised when the underlying data changes.
     * @memberof KmlDataSource.prototype
     * @type {Event}
     */
    changedEvent: {
      get: function () {
        return this._changed;
      },
    },
    /**
     * Gets an event that will be raised if an error is encountered during processing.
     * @memberof KmlDataSource.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._error;
      },
    },
    /**
     * Gets an event that will be raised when the data source either starts or stops loading.
     * @memberof KmlDataSource.prototype
     * @type {Event}
     */
    loadingEvent: {
      get: function () {
        return this._loading;
      },
    },
    /**
     * Gets an event that will be raised when the data source refreshes a network link.
     * @memberof KmlDataSource.prototype
     * @type {Event}
     */
    refreshEvent: {
      get: function () {
        return this._refresh;
      },
    },
    /**
     * Gets an event that will be raised when the data source finds an unsupported node type.
     * @memberof KmlDataSource.prototype
     * @type {Event}
     */
    unsupportedNodeEvent: {
      get: function () {
        return this._unsupportedNode;
      },
    },
    /**
     * Gets whether or not this data source should be displayed.
     * @memberof KmlDataSource.prototype
     * @type {Boolean}
     */
    show: {
      get: function () {
        return this._entityCollection.show;
      },
      set: function (value) {
        this._entityCollection.show = value;
      },
    },

    /**
     * Gets or sets the clustering options for this data source. This object can be shared between multiple data sources.
     *
     * @memberof KmlDataSource.prototype
     * @type {EntityCluster}
     */
    clustering: {
      get: function () {
        return this._entityCluster;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value must be defined.");
        }
        //>>includeEnd('debug');
        this._entityCluster = value;
      },
    },
    /**
     * Gets the credit that will be displayed for the data source
     * @memberof KmlDataSource.prototype
     * @type {Credit}
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },
  });

  /**
   * Asynchronously loads the provided KML data, replacing any existing data.
   *
   * @param {Resource|String|Document|Blob} data A url, parsed KML document, or Blob containing binary KMZ data or a parsed KML document.
   * @param {Object} [options] An object with the following properties:
   * @param {Resource|String} [options.sourceUri] Overrides the url to use for resolving relative links and other KML network features.
   * @param {Boolean} [options.clampToGround=false] true if we want the geometry features (Polygons, LineStrings and LinearRings) clamped to the ground. If true, lines will use corridors so use Entity.corridor instead of Entity.polyline.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The global ellipsoid used for geographical calculations.
   *
   * @returns {Promise.<KmlDataSource>} A promise that will resolve to this instances once the KML is loaded.
   */
  KmlDataSource.prototype.load = function (data, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(data)) {
      throw new DeveloperError("data is required.");
    }
    //>>includeEnd('debug');

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    DataSource.setLoading(this, true);

    var oldName = this._name;
    this._name = undefined;
    this._clampToGround = defaultValue(options.clampToGround, false);

    var that = this;
    return load$2(this, this._entityCollection, data, options)
      .then(function () {
        var clock;

        var availability = that._entityCollection.computeAvailability();

        var start = availability.start;
        var stop = availability.stop;
        var isMinStart = JulianDate.equals(start, Iso8601.MINIMUM_VALUE);
        var isMaxStop = JulianDate.equals(stop, Iso8601.MAXIMUM_VALUE);
        if (!isMinStart || !isMaxStop) {
          var date;

          //If start is min time just start at midnight this morning, local time
          if (isMinStart) {
            date = new Date();
            date.setHours(0, 0, 0, 0);
            start = JulianDate.fromDate(date);
          }

          //If stop is max value just stop at midnight tonight, local time
          if (isMaxStop) {
            date = new Date();
            date.setHours(24, 0, 0, 0);
            stop = JulianDate.fromDate(date);
          }

          clock = new DataSourceClock();
          clock.startTime = start;
          clock.stopTime = stop;
          clock.currentTime = JulianDate.clone(start);
          clock.clockRange = ClockRange$1.LOOP_STOP;
          clock.clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;
          clock.multiplier = Math.round(
            Math.min(
              Math.max(JulianDate.secondsDifference(stop, start) / 60, 1),
              3.15569e7
            )
          );
        }

        var changed = false;
        if (clock !== that._clock) {
          that._clock = clock;
          changed = true;
        }

        if (oldName !== that._name) {
          changed = true;
        }

        if (changed) {
          that._changed.raiseEvent(that);
        }

        DataSource.setLoading(that, false);

        return that;
      })
      .otherwise(function (error) {
        DataSource.setLoading(that, false);
        that._error.raiseEvent(that, error);
        console.log(error);
        return when.reject(error);
      });
  };

  function mergeAvailabilityWithParent(child) {
    var parent = child.parent;
    if (defined(parent)) {
      var parentAvailability = parent.availability;
      if (defined(parentAvailability)) {
        var childAvailability = child.availability;
        if (defined(childAvailability)) {
          childAvailability.intersect(parentAvailability);
        } else {
          child.availability = parentAvailability;
        }
      }
    }
  }

  function getNetworkLinkUpdateCallback(
    dataSource,
    networkLink,
    newEntityCollection,
    networkLinks,
    processedHref
  ) {
    return function (rootElement) {
      if (!networkLinks.contains(networkLink.id)) {
        // Got into the odd case where a parent network link was updated while a child
        //  network link update was in flight, so just throw it away.
        return;
      }
      var remove = false;
      var networkLinkControl = queryFirstNode(
        rootElement,
        "NetworkLinkControl",
        namespaces.kml
      );
      var hasNetworkLinkControl = defined(networkLinkControl);

      var minRefreshPeriod = 0;
      if (hasNetworkLinkControl) {
        if (
          defined(queryFirstNode(networkLinkControl, "Update", namespaces.kml))
        ) {
          oneTimeWarning(
            "kml-networkLinkControl-update",
            "KML - NetworkLinkControl updates aren't supported."
          );
          networkLink.updating = false;
          networkLinks.remove(networkLink.id);
          return;
        }
        networkLink.cookie = queryToObject(
          defaultValue(
            queryStringValue(networkLinkControl, "cookie", namespaces.kml),
            ""
          )
        );
        minRefreshPeriod = defaultValue(
          queryNumericValue(
            networkLinkControl,
            "minRefreshPeriod",
            namespaces.kml
          ),
          0
        );
      }

      var now = JulianDate.now();
      var refreshMode = networkLink.refreshMode;
      if (refreshMode === RefreshMode.INTERVAL) {
        if (defined(networkLinkControl)) {
          networkLink.time = Math.max(minRefreshPeriod, networkLink.time);
        }
      } else if (refreshMode === RefreshMode.EXPIRE) {
        var expires;
        if (defined(networkLinkControl)) {
          expires = queryStringValue(
            networkLinkControl,
            "expires",
            namespaces.kml
          );
        }
        if (defined(expires)) {
          try {
            var date = JulianDate.fromIso8601(expires);
            var diff = JulianDate.secondsDifference(date, now);
            if (diff > 0 && diff < minRefreshPeriod) {
              JulianDate.addSeconds(now, minRefreshPeriod, date);
            }
            networkLink.time = date;
          } catch (e) {
            oneTimeWarning(
              "kml-networkLinkControl-expires",
              "KML - NetworkLinkControl expires is not a valid date"
            );
            remove = true;
          }
        } else {
          oneTimeWarning(
            "kml-refreshMode-onExpire",
            "KML - refreshMode of onExpire requires the NetworkLinkControl to have an expires element"
          );
          remove = true;
        }
      }

      var networkLinkEntity = networkLink.entity;
      var entityCollection = dataSource._entityCollection;
      var newEntities = newEntityCollection.values;

      function removeChildren(entity) {
        entityCollection.remove(entity);
        var children = entity._children;
        var count = children.length;
        for (var i = 0; i < count; ++i) {
          removeChildren(children[i]);
        }
      }

      // Remove old entities
      entityCollection.suspendEvents();
      var entitiesCopy = entityCollection.values.slice();
      var i;
      for (i = 0; i < entitiesCopy.length; ++i) {
        var entityToRemove = entitiesCopy[i];
        if (entityToRemove.parent === networkLinkEntity) {
          entityToRemove.parent = undefined;
          removeChildren(entityToRemove);
        }
      }
      entityCollection.resumeEvents();

      // Add new entities
      entityCollection.suspendEvents();
      for (i = 0; i < newEntities.length; i++) {
        var newEntity = newEntities[i];
        if (!defined(newEntity.parent)) {
          newEntity.parent = networkLinkEntity;
          mergeAvailabilityWithParent(newEntity);
        }
        entityCollection.add(newEntity);
      }
      entityCollection.resumeEvents();

      // No refresh information remove it, otherwise update lastUpdate time
      if (remove) {
        networkLinks.remove(networkLink.id);
      } else {
        networkLink.lastUpdated = now;
      }

      var availability = entityCollection.computeAvailability();

      var start = availability.start;
      var stop = availability.stop;
      var isMinStart = JulianDate.equals(start, Iso8601.MINIMUM_VALUE);
      var isMaxStop = JulianDate.equals(stop, Iso8601.MAXIMUM_VALUE);
      if (!isMinStart || !isMaxStop) {
        var clock = dataSource._clock;

        if (clock.startTime !== start || clock.stopTime !== stop) {
          clock.startTime = start;
          clock.stopTime = stop;
          dataSource._changed.raiseEvent(dataSource);
        }
      }

      networkLink.updating = false;
      networkLink.needsUpdate = false;
      dataSource._refresh.raiseEvent(
        dataSource,
        processedHref.getUrlComponent(true)
      );
    };
  }

  var entitiesToIgnore = new AssociativeArray();

  /**
   * Updates any NetworkLink that require updating.
   *
   * @param {JulianDate} time The simulation time.
   * @returns {Boolean} True if this data source is ready to be displayed at the provided time, false otherwise.
   */
  KmlDataSource.prototype.update = function (time) {
    var networkLinks = this._networkLinks;
    if (networkLinks.length === 0) {
      return true;
    }

    var now = JulianDate.now();
    var that = this;

    entitiesToIgnore.removeAll();

    function recurseIgnoreEntities(entity) {
      var children = entity._children;
      var count = children.length;
      for (var i = 0; i < count; ++i) {
        var child = children[i];
        entitiesToIgnore.set(child.id, child);
        recurseIgnoreEntities(child);
      }
    }

    var cameraViewUpdate = false;
    var lastCameraView = this._lastCameraView;
    var camera = this._camera;
    if (
      defined(camera) &&
      !(
        camera.positionWC.equalsEpsilon(
          lastCameraView.position,
          CesiumMath.EPSILON7
        ) &&
        camera.directionWC.equalsEpsilon(
          lastCameraView.direction,
          CesiumMath.EPSILON7
        ) &&
        camera.upWC.equalsEpsilon(lastCameraView.up, CesiumMath.EPSILON7)
      )
    ) {
      // Camera has changed so update the last view
      lastCameraView.position = Cartesian3.clone(camera.positionWC);
      lastCameraView.direction = Cartesian3.clone(camera.directionWC);
      lastCameraView.up = Cartesian3.clone(camera.upWC);
      lastCameraView.bbox = camera.computeViewRectangle();
      cameraViewUpdate = true;
    }

    var newNetworkLinks = new AssociativeArray();
    var changed = false;
    networkLinks.values.forEach(function (networkLink) {
      var entity = networkLink.entity;
      if (entitiesToIgnore.contains(entity.id)) {
        return;
      }

      if (!networkLink.updating) {
        var doUpdate = false;
        if (networkLink.refreshMode === RefreshMode.INTERVAL) {
          if (
            JulianDate.secondsDifference(now, networkLink.lastUpdated) >
            networkLink.time
          ) {
            doUpdate = true;
          }
        } else if (networkLink.refreshMode === RefreshMode.EXPIRE) {
          if (JulianDate.greaterThan(now, networkLink.time)) {
            doUpdate = true;
          }
        } else if (networkLink.refreshMode === RefreshMode.STOP) {
          if (cameraViewUpdate) {
            networkLink.needsUpdate = true;
            networkLink.cameraUpdateTime = now;
          }

          if (
            networkLink.needsUpdate &&
            JulianDate.secondsDifference(now, networkLink.cameraUpdateTime) >=
              networkLink.time
          ) {
            doUpdate = true;
          }
        }

        if (doUpdate) {
          recurseIgnoreEntities(entity);
          networkLink.updating = true;
          var newEntityCollection = new EntityCollection();
          var href = networkLink.href.clone();

          href.setQueryParameters(networkLink.cookie);
          var ellipsoid = defaultValue(that._ellipsoid, Ellipsoid.WGS84);
          processNetworkLinkQueryString(
            href,
            that._camera,
            that._canvas,
            networkLink.viewBoundScale,
            lastCameraView.bbox,
            ellipsoid
          );

          load$2(that, newEntityCollection, href, { context: entity.id })
            .then(
              getNetworkLinkUpdateCallback(
                that,
                networkLink,
                newEntityCollection,
                newNetworkLinks,
                href
              )
            )
            .otherwise(function (error) {
              var msg =
                "NetworkLink " + networkLink.href + " refresh failed: " + error;
              console.log(msg);
              that._error.raiseEvent(that, msg);
            });
          changed = true;
        }
      }
      newNetworkLinks.set(networkLink.id, networkLink);
    });

    if (changed) {
      this._networkLinks = newNetworkLinks;
      this._changed.raiseEvent(this);
    }

    return true;
  };

  /**
   * Contains KML Feature data loaded into the <code>Entity.kml</code> property by {@link KmlDataSource}.
   * @alias KmlFeatureData
   * @constructor
   */
  function KmlFeatureData() {
    /**
     * @typedef KmlFeatureData.Author
     * @type {Object}
     * @property {String} name Gets the name.
     * @property {String} uri Gets the URI.
     * @property {Number} age Gets the email.
     */

    /**
     * Gets the atom syndication format author field.
     * @type {KmlFeatureData.Author}
     */
    this.author = {
      name: undefined,
      uri: undefined,
      email: undefined,
    };

    /**
     * @typedef KmlFeatureData.Link
     * @type {Object}
     * @property {String} href Gets the href.
     * @property {String} hreflang Gets the language of the linked resource.
     * @property {String} rel Gets the link relation.
     * @property {String} type Gets the link type.
     * @property {String} title Gets the link title.
     * @property {String} length Gets the link length.
     */

    /**
     * Gets the link.
     * @type {KmlFeatureData.Link}
     */
    this.link = {
      href: undefined,
      hreflang: undefined,
      rel: undefined,
      type: undefined,
      title: undefined,
      length: undefined,
    };

    /**
     * Gets the unstructured address field.
     * @type {String}
     */
    this.address = undefined;
    /**
     * Gets the phone number.
     * @type {String}
     */
    this.phoneNumber = undefined;
    /**
     * Gets the snippet.
     * @type {String}
     */
    this.snippet = undefined;
    /**
     * Gets the extended data, parsed into a JSON object.
     * Currently only the <code>Data</code> property is supported.
     * <code>SchemaData</code> and custom data are ignored.
     * @type {String}
     */
    this.extendedData = undefined;
  }

  // For testing
  KmlDataSource._DeferredLoading = DeferredLoading;
  KmlDataSource._getTimestamp = getTimestamp$1;

  /**
   * Defines the interface for visualizers. Visualizers are plug-ins to
   * {@link DataSourceDisplay} that render data associated with
   * {@link DataSource} instances.
   * This object is an interface for documentation purposes and is not intended
   * to be instantiated directly.
   * @alias Visualizer
   * @constructor
   *
   * @see BillboardVisualizer
   * @see LabelVisualizer
   * @see ModelVisualizer
   * @see PathVisualizer
   * @see PointVisualizer
   * @see GeometryVisualizer
   */
  function Visualizer() {
    DeveloperError.throwInstantiationError();
  }

  /**
   * Updates the visualization to the provided time.
   * @function
   *
   * @param {JulianDate} time The time.
   *
   * @returns {Boolean} True if the display was updated to the provided time,
   * false if the visualizer is waiting for an asynchronous operation to
   * complete before data can be updated.
   */
  Visualizer.prototype.update = DeveloperError.throwInstantiationError;

  /**
   * Computes a bounding sphere which encloses the visualization produced for the specified entity.
   * The bounding sphere is in the fixed frame of the scene's globe.
   *
   * @param {Entity} entity The entity whose bounding sphere to compute.
   * @param {BoundingSphere} result The bounding sphere onto which to store the result.
   * @returns {BoundingSphereState} BoundingSphereState.DONE if the result contains the bounding sphere,
   *                       BoundingSphereState.PENDING if the result is still being computed, or
   *                       BoundingSphereState.FAILED if the entity has no visualization in the current scene.
   * @private
   */
  Visualizer.prototype.getBoundingSphere = DeveloperError.throwInstantiationError;

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * @function
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   */
  Visualizer.prototype.isDestroyed = DeveloperError.throwInstantiationError;

  /**
   * Removes all visualization and cleans up any resources associated with this instance.
   * @function
   */
  Visualizer.prototype.destroy = DeveloperError.throwInstantiationError;

  var BILLBOARD_SIZE$1 = 32;
  var kmlNamespace = "http://www.opengis.net/kml/2.2";
  var gxNamespace = "http://www.google.com/kml/ext/2.2";
  var xmlnsNamespace = "http://www.w3.org/2000/xmlns/";

  //
  // Handles files external to the KML (eg. textures and models)
  //
  function ExternalFileHandler(modelCallback) {
    this._files = {};
    this._promises = [];
    this._count = 0;
    this._modelCallback = modelCallback;
  }

  var imageTypeRegex = /^data:image\/([^,;]+)/;
  ExternalFileHandler.prototype.texture = function (texture) {
    var that = this;
    var filename;

    if (typeof texture === "string" || texture instanceof Resource) {
      texture = Resource.createIfNeeded(texture);
      if (!texture.isDataUri) {
        return texture.url;
      }

      // If its a data URI try and get the correct extension and then fetch the blob
      var regexResult = texture.url.match(imageTypeRegex);
      filename = "texture_" + ++this._count;
      if (defined(regexResult)) {
        filename += "." + regexResult[1];
      }

      var promise = texture.fetchBlob().then(function (blob) {
        that._files[filename] = blob;
      });

      this._promises.push(promise);

      return filename;
    }

    if (texture instanceof HTMLCanvasElement) {
      var deferred = when.defer();
      this._promises.push(deferred.promise);

      filename = "texture_" + ++this._count + ".png";
      texture.toBlob(function (blob) {
        that._files[filename] = blob;
        deferred.resolve();
      });

      return filename;
    }

    return "";
  };

  function getModelBlobHander(that, filename) {
    return function (blob) {
      that._files[filename] = blob;
    };
  }

  ExternalFileHandler.prototype.model = function (model, time) {
    var modelCallback = this._modelCallback;
    if (!defined(modelCallback)) {
      throw new RuntimeError(
        "Encountered a model entity while exporting to KML, but no model callback was supplied."
      );
    }

    var externalFiles = {};
    var url = modelCallback(model, time, externalFiles);

    // Iterate through external files and add them to our list once the promise resolves
    for (var filename in externalFiles) {
      if (externalFiles.hasOwnProperty(filename)) {
        var promise = when(externalFiles[filename]);
        this._promises.push(promise);

        promise.then(getModelBlobHander(this, filename));
      }
    }

    return url;
  };

  Object.defineProperties(ExternalFileHandler.prototype, {
    promise: {
      get: function () {
        return when.all(this._promises);
      },
    },
    files: {
      get: function () {
        return this._files;
      },
    },
  });

  //
  // Handles getting values from properties taking the desired time and default values into account
  //
  function ValueGetter(time) {
    this._time = time;
  }

  ValueGetter.prototype.get = function (property, defaultVal, result) {
    var value;
    if (defined(property)) {
      value = defined(property.getValue)
        ? property.getValue(this._time, result)
        : property;
    }

    return defaultValue(value, defaultVal);
  };

  ValueGetter.prototype.getColor = function (property, defaultVal) {
    var result = this.get(property, defaultVal);
    if (defined(result)) {
      return colorToString(result);
    }
  };

  ValueGetter.prototype.getMaterialType = function (property) {
    if (!defined(property)) {
      return;
    }

    return property.getType(this._time);
  };

  //
  // Caches styles so we don't generate a ton of duplicate styles
  //
  function StyleCache() {
    this._ids = {};
    this._styles = {};
    this._count = 0;
  }

  StyleCache.prototype.get = function (element) {
    var ids = this._ids;
    var key = element.innerHTML;
    if (defined(ids[key])) {
      return ids[key];
    }

    var styleId = "style-" + ++this._count;
    element.setAttribute("id", styleId);

    // Store with #
    styleId = "#" + styleId;
    ids[key] = styleId;
    this._styles[key] = element;

    return styleId;
  };

  StyleCache.prototype.save = function (parentElement) {
    var styles = this._styles;

    var firstElement = parentElement.childNodes[0];
    for (var key in styles) {
      if (styles.hasOwnProperty(key)) {
        parentElement.insertBefore(styles[key], firstElement);
      }
    }
  };

  //
  // Manages the generation of IDs because an entity may have geometry and a Folder for children
  //
  function IdManager() {
    this._ids = {};
  }

  IdManager.prototype.get = function (id) {
    if (!defined(id)) {
      return this.get(createGuid());
    }

    var ids = this._ids;
    if (!defined(ids[id])) {
      ids[id] = 0;
      return id;
    }

    return id.toString() + "-" + ++ids[id];
  };

  /**
   * @typedef exportKmlResultKml
   * @type {Object}
   * @property {String} kml The generated KML.
   * @property {Object.<string, Blob>} externalFiles An object dictionary of external files
   */

  /**
   * @typedef exportKmlResultKmz
   * @type {Object}
   * @property {Blob} kmz The generated kmz file.
   */

  /**
   * Exports an EntityCollection as a KML document. Only Point, Billboard, Model, Path, Polygon, Polyline geometries
   * will be exported. Note that there is not a 1 to 1 mapping of Entity properties to KML Feature properties. For
   * example, entity properties that are time dynamic but cannot be dynamic in KML are exported with their values at
   * options.time or the beginning of the EntityCollection's time interval if not specified. For time-dynamic properties
   * that are supported in KML, we use the samples if it is a {@link SampledProperty} otherwise we sample the value using
   * the options.sampleDuration. Point, Billboard, Model and Path geometries with time-dynamic positions will be exported
   * as gx:Track Features. Not all Materials are representable in KML, so for more advanced Materials just the primary
   * color is used. Canvas objects are exported as PNG images.
   *
   * @function exportKml
   *
   * @param {Object} options An object with the following properties:
   * @param {EntityCollection} options.entities The EntityCollection to export as KML.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid for the output file.
   * @param {exportKmlModelCallback} [options.modelCallback] A callback that will be called with a {@link ModelGraphics} instance and should return the URI to use in the KML. Required if a model exists in the entity collection.
   * @param {JulianDate} [options.time=entities.computeAvailability().start] The time value to use to get properties that are not time varying in KML.
   * @param {TimeInterval} [options.defaultAvailability=entities.computeAvailability()] The interval that will be sampled if an entity doesn't have an availability.
   * @param {Number} [options.sampleDuration=60] The number of seconds to sample properties that are varying in KML.
   * @param {Boolean} [options.kmz=false] If true KML and external files will be compressed into a kmz file.
   *
   * @returns {Promise<exportKmlResultKml|exportKmlResultKmz>} A promise that resolved to an object containing the KML string and a dictionary of external file blobs, or a kmz file as a blob if options.kmz is true.
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Export%20KML.html|Cesium Sandcastle KML Export Demo}
   * @example
   * Cesium.exportKml({
   *      entities: entityCollection
   *  })
   *   .then(function(result) {
   *     // The XML string is in result.kml
   *
   *     var externalFiles = result.externalFiles
   *     for(var file in externalFiles) {
   *       // file is the name of the file used in the KML document as the href
   *       // externalFiles[file] is a blob with the contents of the file
   *     }
   *   });
   *
   */
  function exportKml(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var entities = options.entities;
    var kmz = defaultValue(options.kmz, false);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(entities)) {
      throw new DeveloperError("entities is required.");
    }
    //>>includeEnd('debug');

    // Get the state that is passed around during the recursion
    // This is separated out for testing.
    var state = exportKml._createState(options);

    // Filter EntityCollection so we only have top level entities
    var rootEntities = entities.values.filter(function (entity) {
      return !defined(entity.parent);
    });

    // Add the <Document>
    var kmlDoc = state.kmlDoc;
    var kmlElement = kmlDoc.documentElement;
    kmlElement.setAttributeNS(xmlnsNamespace, "xmlns:gx", gxNamespace);
    var kmlDocumentElement = kmlDoc.createElement("Document");
    kmlElement.appendChild(kmlDocumentElement);

    // Create the KML Hierarchy
    recurseEntities(state, kmlDocumentElement, rootEntities);

    // Write out the <Style> elements
    state.styleCache.save(kmlDocumentElement);

    // Once all the blobs have resolved return the KML string along with the blob collection
    var externalFileHandler = state.externalFileHandler;
    return externalFileHandler.promise.then(function () {
      var serializer = new XMLSerializer();
      var kmlString = serializer.serializeToString(state.kmlDoc);
      if (kmz) {
        return createKmz(kmlString, externalFileHandler.files);
      }

      return {
        kml: kmlString,
        externalFiles: externalFileHandler.files,
      };
    });
  }

  function createKmz(kmlString, externalFiles) {
    var deferred = when.defer();
    zip.createWriter(new zip.BlobWriter(), function (writer) {
      // We need to only write one file at a time so the zip doesn't get corrupted
      addKmlToZip(writer, kmlString)
        .then(function () {
          var keys = Object.keys(externalFiles);
          return addExternalFilesToZip(writer, keys, externalFiles, 0);
        })
        .then(function () {
          writer.close(function (blob) {
            deferred.resolve({
              kmz: blob,
            });
          });
        });
    });

    return deferred.promise;
  }

  function addKmlToZip(writer, kmlString) {
    var deferred = when.defer();
    writer.add("doc.kml", new zip.TextReader(kmlString), function () {
      deferred.resolve();
    });

    return deferred.promise;
  }

  function addExternalFilesToZip(writer, keys, externalFiles, index) {
    if (keys.length === index) {
      return;
    }

    var filename = keys[index];

    var deferred = when.defer();
    writer.add(
      filename,
      new zip.BlobReader(externalFiles[filename]),
      function () {
        deferred.resolve();
      }
    );

    return deferred.promise.then(function () {
      return addExternalFilesToZip(writer, keys, externalFiles, index + 1);
    });
  }

  exportKml._createState = function (options) {
    var entities = options.entities;

    var styleCache = new StyleCache();

    // Use the start time as the default because just in case they define
    //  properties with an interval even if they don't change.
    var entityAvailability = entities.computeAvailability();
    var time = defined(options.time) ? options.time : entityAvailability.start;

    // Figure out how we will sample dynamic position properties
    var defaultAvailability = defaultValue(
      options.defaultAvailability,
      entityAvailability
    );
    var sampleDuration = defaultValue(options.sampleDuration, 60);

    // Make sure we don't have infinite availability if we need to sample
    if (defaultAvailability.start === Iso8601.MINIMUM_VALUE) {
      if (defaultAvailability.stop === Iso8601.MAXIMUM_VALUE) {
        // Infinite, so just use the default
        defaultAvailability = new TimeInterval();
      } else {
        // No start time, so just sample 10 times before the stop
        JulianDate.addSeconds(
          defaultAvailability.stop,
          -10 * sampleDuration,
          defaultAvailability.start
        );
      }
    } else if (defaultAvailability.stop === Iso8601.MAXIMUM_VALUE) {
      // No stop time, so just sample 10 times after the start
      JulianDate.addSeconds(
        defaultAvailability.start,
        10 * sampleDuration,
        defaultAvailability.stop
      );
    }

    var externalFileHandler = new ExternalFileHandler(options.modelCallback);

    var kmlDoc = document.implementation.createDocument(kmlNamespace, "kml");
    return {
      kmlDoc: kmlDoc,
      ellipsoid: defaultValue(options.ellipsoid, Ellipsoid.WGS84),
      idManager: new IdManager(),
      styleCache: styleCache,
      externalFileHandler: externalFileHandler,
      time: time,
      valueGetter: new ValueGetter(time),
      sampleDuration: sampleDuration,
      // Wrap it in a TimeIntervalCollection because that is what entity.availability is
      defaultAvailability: new TimeIntervalCollection([defaultAvailability]),
    };
  };

  function recurseEntities(state, parentNode, entities) {
    var kmlDoc = state.kmlDoc;
    var styleCache = state.styleCache;
    var valueGetter = state.valueGetter;
    var idManager = state.idManager;

    var count = entities.length;
    var overlays;
    var geometries;
    var styles;
    for (var i = 0; i < count; ++i) {
      var entity = entities[i];
      overlays = [];
      geometries = [];
      styles = [];

      createPoint$1(state, entity, geometries, styles);
      createLineString$1(state, entity.polyline, geometries, styles);
      createPolygon$1(state, entity.rectangle, geometries, styles, overlays);
      createPolygon$1(state, entity.polygon, geometries, styles, overlays);
      createModel$1(state, entity, entity.model, geometries, styles);

      var timeSpan;
      var availability = entity.availability;
      if (defined(availability)) {
        timeSpan = kmlDoc.createElement("TimeSpan");

        if (!JulianDate.equals(availability.start, Iso8601.MINIMUM_VALUE)) {
          timeSpan.appendChild(
            createBasicElementWithText(
              kmlDoc,
              "begin",
              JulianDate.toIso8601(availability.start)
            )
          );
        }

        if (!JulianDate.equals(availability.stop, Iso8601.MAXIMUM_VALUE)) {
          timeSpan.appendChild(
            createBasicElementWithText(
              kmlDoc,
              "end",
              JulianDate.toIso8601(availability.stop)
            )
          );
        }
      }

      for (var overlayIndex = 0; overlayIndex < overlays.length; ++overlayIndex) {
        var overlay = overlays[overlayIndex];

        overlay.setAttribute("id", idManager.get(entity.id));
        overlay.appendChild(
          createBasicElementWithText(kmlDoc, "name", entity.name)
        );
        overlay.appendChild(
          createBasicElementWithText(kmlDoc, "visibility", entity.show)
        );
        overlay.appendChild(
          createBasicElementWithText(kmlDoc, "description", entity.description)
        );

        if (defined(timeSpan)) {
          overlay.appendChild(timeSpan);
        }

        parentNode.appendChild(overlay);
      }

      var geometryCount = geometries.length;
      if (geometryCount > 0) {
        var placemark = kmlDoc.createElement("Placemark");
        placemark.setAttribute("id", idManager.get(entity.id));

        var name = entity.name;
        var labelGraphics = entity.label;
        if (defined(labelGraphics)) {
          var labelStyle = kmlDoc.createElement("LabelStyle");

          // KML only shows the name as a label, so just change the name if we need to show a label
          var text = valueGetter.get(labelGraphics.text);
          name = defined(text) && text.length > 0 ? text : name;

          var color = valueGetter.getColor(labelGraphics.fillColor);
          if (defined(color)) {
            labelStyle.appendChild(
              createBasicElementWithText(kmlDoc, "color", color)
            );
            labelStyle.appendChild(
              createBasicElementWithText(kmlDoc, "colorMode", "normal")
            );
          }

          var scale = valueGetter.get(labelGraphics.scale);
          if (defined(scale)) {
            labelStyle.appendChild(
              createBasicElementWithText(kmlDoc, "scale", scale)
            );
          }

          styles.push(labelStyle);
        }

        placemark.appendChild(createBasicElementWithText(kmlDoc, "name", name));
        placemark.appendChild(
          createBasicElementWithText(kmlDoc, "visibility", entity.show)
        );
        placemark.appendChild(
          createBasicElementWithText(kmlDoc, "description", entity.description)
        );

        if (defined(timeSpan)) {
          placemark.appendChild(timeSpan);
        }

        parentNode.appendChild(placemark);

        var styleCount = styles.length;
        if (styleCount > 0) {
          var style = kmlDoc.createElement("Style");
          for (var styleIndex = 0; styleIndex < styleCount; ++styleIndex) {
            style.appendChild(styles[styleIndex]);
          }

          placemark.appendChild(
            createBasicElementWithText(kmlDoc, "styleUrl", styleCache.get(style))
          );
        }

        if (geometries.length === 1) {
          placemark.appendChild(geometries[0]);
        } else if (geometries.length > 1) {
          var multigeometry = kmlDoc.createElement("MultiGeometry");
          for (
            var geometryIndex = 0;
            geometryIndex < geometryCount;
            ++geometryIndex
          ) {
            multigeometry.appendChild(geometries[geometryIndex]);
          }
          placemark.appendChild(multigeometry);
        }
      }

      var children = entity._children;
      if (children.length > 0) {
        var folderNode = kmlDoc.createElement("Folder");
        folderNode.setAttribute("id", idManager.get(entity.id));
        folderNode.appendChild(
          createBasicElementWithText(kmlDoc, "name", entity.name)
        );
        folderNode.appendChild(
          createBasicElementWithText(kmlDoc, "visibility", entity.show)
        );
        folderNode.appendChild(
          createBasicElementWithText(kmlDoc, "description", entity.description)
        );

        parentNode.appendChild(folderNode);

        recurseEntities(state, folderNode, children);
      }
    }
  }

  var scratchCartesian3$b = new Cartesian3();
  var scratchCartographic$a = new Cartographic();
  var scratchJulianDate$2 = new JulianDate();

  function createPoint$1(state, entity, geometries, styles) {
    var kmlDoc = state.kmlDoc;
    var ellipsoid = state.ellipsoid;
    var valueGetter = state.valueGetter;

    var pointGraphics = defaultValue(entity.billboard, entity.point);
    if (!defined(pointGraphics) && !defined(entity.path)) {
      return;
    }

    // If the point isn't constant then create gx:Track or gx:MultiTrack
    var entityPositionProperty = entity.position;
    if (!entityPositionProperty.isConstant) {
      createTracks(state, entity, pointGraphics, geometries, styles);
      return;
    }

    valueGetter.get(entityPositionProperty, undefined, scratchCartesian3$b);
    var coordinates = createBasicElementWithText(
      kmlDoc,
      "coordinates",
      getCoordinates(scratchCartesian3$b, ellipsoid)
    );

    var pointGeometry = kmlDoc.createElement("Point");

    // Set altitude mode
    var altitudeMode = kmlDoc.createElement("altitudeMode");
    altitudeMode.appendChild(
      getAltitudeMode(state, pointGraphics.heightReference)
    );
    pointGeometry.appendChild(altitudeMode);

    pointGeometry.appendChild(coordinates);
    geometries.push(pointGeometry);

    // Create style
    var iconStyle =
      pointGraphics instanceof BillboardGraphics
        ? createIconStyleFromBillboard(state, pointGraphics)
        : createIconStyleFromPoint(state, pointGraphics);
    styles.push(iconStyle);
  }

  function createTracks(state, entity, pointGraphics, geometries, styles) {
    var kmlDoc = state.kmlDoc;
    var ellipsoid = state.ellipsoid;
    var valueGetter = state.valueGetter;

    var intervals;
    var entityPositionProperty = entity.position;
    var useEntityPositionProperty = true;
    if (entityPositionProperty instanceof CompositePositionProperty) {
      intervals = entityPositionProperty.intervals;
      useEntityPositionProperty = false;
    } else {
      intervals = defaultValue(entity.availability, state.defaultAvailability);
    }

    var isModel = pointGraphics instanceof ModelGraphics;

    var i, j, times;
    var tracks = [];
    for (i = 0; i < intervals.length; ++i) {
      var interval = intervals.get(i);
      var positionProperty = useEntityPositionProperty
        ? entityPositionProperty
        : interval.data;

      var trackAltitudeMode = kmlDoc.createElement("altitudeMode");
      // This is something that KML importing uses to handle clampToGround,
      //  so just extract the internal property and set the altitudeMode.
      if (positionProperty instanceof ScaledPositionProperty) {
        positionProperty = positionProperty._value;
        trackAltitudeMode.appendChild(
          getAltitudeMode(state, HeightReference$1.CLAMP_TO_GROUND)
        );
      } else if (defined(pointGraphics)) {
        trackAltitudeMode.appendChild(
          getAltitudeMode(state, pointGraphics.heightReference)
        );
      } else {
        // Path graphics only, which has no height reference
        trackAltitudeMode.appendChild(
          getAltitudeMode(state, HeightReference$1.NONE)
        );
      }

      var positionTimes = [];
      var positionValues = [];

      if (positionProperty.isConstant) {
        valueGetter.get(positionProperty, undefined, scratchCartesian3$b);
        var constCoordinates = createBasicElementWithText(
          kmlDoc,
          "coordinates",
          getCoordinates(scratchCartesian3$b, ellipsoid)
        );

        // This interval is constant so add a track with the same position
        positionTimes.push(JulianDate.toIso8601(interval.start));
        positionValues.push(constCoordinates);
        positionTimes.push(JulianDate.toIso8601(interval.stop));
        positionValues.push(constCoordinates);
      } else if (positionProperty instanceof SampledPositionProperty) {
        times = positionProperty._property._times;

        for (j = 0; j < times.length; ++j) {
          positionTimes.push(JulianDate.toIso8601(times[j]));
          positionProperty.getValueInReferenceFrame(
            times[j],
            ReferenceFrame$1.FIXED,
            scratchCartesian3$b
          );
          positionValues.push(getCoordinates(scratchCartesian3$b, ellipsoid));
        }
      } else if (positionProperty instanceof SampledProperty) {
        times = positionProperty._times;
        var values = positionProperty._values;

        for (j = 0; j < times.length; ++j) {
          positionTimes.push(JulianDate.toIso8601(times[j]));
          Cartesian3.fromArray(values, j * 3, scratchCartesian3$b);
          positionValues.push(getCoordinates(scratchCartesian3$b, ellipsoid));
        }
      } else {
        var duration = state.sampleDuration;
        interval.start.clone(scratchJulianDate$2);
        if (!interval.isStartIncluded) {
          JulianDate.addSeconds(scratchJulianDate$2, duration, scratchJulianDate$2);
        }

        var stopDate = interval.stop;
        while (JulianDate.lessThan(scratchJulianDate$2, stopDate)) {
          positionProperty.getValue(scratchJulianDate$2, scratchCartesian3$b);

          positionTimes.push(JulianDate.toIso8601(scratchJulianDate$2));
          positionValues.push(getCoordinates(scratchCartesian3$b, ellipsoid));

          JulianDate.addSeconds(scratchJulianDate$2, duration, scratchJulianDate$2);
        }

        if (
          interval.isStopIncluded &&
          JulianDate.equals(scratchJulianDate$2, stopDate)
        ) {
          positionProperty.getValue(scratchJulianDate$2, scratchCartesian3$b);

          positionTimes.push(JulianDate.toIso8601(scratchJulianDate$2));
          positionValues.push(getCoordinates(scratchCartesian3$b, ellipsoid));
        }
      }

      var trackGeometry = kmlDoc.createElementNS(gxNamespace, "Track");
      trackGeometry.appendChild(trackAltitudeMode);

      for (var k = 0; k < positionTimes.length; ++k) {
        var when = createBasicElementWithText(kmlDoc, "when", positionTimes[k]);
        var coord = createBasicElementWithText(
          kmlDoc,
          "coord",
          positionValues[k],
          gxNamespace
        );

        trackGeometry.appendChild(when);
        trackGeometry.appendChild(coord);
      }

      if (isModel) {
        trackGeometry.appendChild(createModelGeometry(state, pointGraphics));
      }

      tracks.push(trackGeometry);
    }

    // If one track, then use it otherwise combine into a multitrack
    if (tracks.length === 1) {
      geometries.push(tracks[0]);
    } else if (tracks.length > 1) {
      var multiTrackGeometry = kmlDoc.createElementNS(gxNamespace, "MultiTrack");

      for (i = 0; i < tracks.length; ++i) {
        multiTrackGeometry.appendChild(tracks[i]);
      }

      geometries.push(multiTrackGeometry);
    }

    // Create style
    if (defined(pointGraphics) && !isModel) {
      var iconStyle =
        pointGraphics instanceof BillboardGraphics
          ? createIconStyleFromBillboard(state, pointGraphics)
          : createIconStyleFromPoint(state, pointGraphics);
      styles.push(iconStyle);
    }

    // See if we have a line that needs to be drawn
    var path = entity.path;
    if (defined(path)) {
      var width = valueGetter.get(path.width);
      var material = path.material;
      if (defined(material) || defined(width)) {
        var lineStyle = kmlDoc.createElement("LineStyle");
        if (defined(width)) {
          lineStyle.appendChild(
            createBasicElementWithText(kmlDoc, "width", width)
          );
        }

        processMaterial(state, material, lineStyle);
        styles.push(lineStyle);
      }
    }
  }

  function createIconStyleFromPoint(state, pointGraphics) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;

    var iconStyle = kmlDoc.createElement("IconStyle");

    var color = valueGetter.getColor(pointGraphics.color);
    if (defined(color)) {
      iconStyle.appendChild(createBasicElementWithText(kmlDoc, "color", color));
      iconStyle.appendChild(
        createBasicElementWithText(kmlDoc, "colorMode", "normal")
      );
    }

    var pixelSize = valueGetter.get(pointGraphics.pixelSize);
    if (defined(pixelSize)) {
      iconStyle.appendChild(
        createBasicElementWithText(kmlDoc, "scale", pixelSize / BILLBOARD_SIZE$1)
      );
    }

    return iconStyle;
  }

  function createIconStyleFromBillboard(state, billboardGraphics) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;
    var externalFileHandler = state.externalFileHandler;

    var iconStyle = kmlDoc.createElement("IconStyle");

    var image = valueGetter.get(billboardGraphics.image);
    if (defined(image)) {
      image = externalFileHandler.texture(image);

      var icon = kmlDoc.createElement("Icon");
      icon.appendChild(createBasicElementWithText(kmlDoc, "href", image));

      var imageSubRegion = valueGetter.get(billboardGraphics.imageSubRegion);
      if (defined(imageSubRegion)) {
        icon.appendChild(
          createBasicElementWithText(kmlDoc, "x", imageSubRegion.x, gxNamespace)
        );
        icon.appendChild(
          createBasicElementWithText(kmlDoc, "y", imageSubRegion.y, gxNamespace)
        );
        icon.appendChild(
          createBasicElementWithText(
            kmlDoc,
            "w",
            imageSubRegion.width,
            gxNamespace
          )
        );
        icon.appendChild(
          createBasicElementWithText(
            kmlDoc,
            "h",
            imageSubRegion.height,
            gxNamespace
          )
        );
      }

      iconStyle.appendChild(icon);
    }

    var color = valueGetter.getColor(billboardGraphics.color);
    if (defined(color)) {
      iconStyle.appendChild(createBasicElementWithText(kmlDoc, "color", color));
      iconStyle.appendChild(
        createBasicElementWithText(kmlDoc, "colorMode", "normal")
      );
    }

    var scale = valueGetter.get(billboardGraphics.scale);
    if (defined(scale)) {
      iconStyle.appendChild(createBasicElementWithText(kmlDoc, "scale", scale));
    }

    var pixelOffset = valueGetter.get(billboardGraphics.pixelOffset);
    if (defined(pixelOffset)) {
      scale = defaultValue(scale, 1.0);

      Cartesian2.divideByScalar(pixelOffset, scale, pixelOffset);

      var width = valueGetter.get(billboardGraphics.width, BILLBOARD_SIZE$1);
      var height = valueGetter.get(billboardGraphics.height, BILLBOARD_SIZE$1);

      // KML Hotspots are from the bottom left, but we work from the top left

      // Move to left
      var horizontalOrigin = valueGetter.get(
        billboardGraphics.horizontalOrigin,
        HorizontalOrigin$1.CENTER
      );
      if (horizontalOrigin === HorizontalOrigin$1.CENTER) {
        pixelOffset.x -= width * 0.5;
      } else if (horizontalOrigin === HorizontalOrigin$1.RIGHT) {
        pixelOffset.x -= width;
      }

      // Move to bottom
      var verticalOrigin = valueGetter.get(
        billboardGraphics.verticalOrigin,
        VerticalOrigin$1.CENTER
      );
      if (verticalOrigin === VerticalOrigin$1.TOP) {
        pixelOffset.y += height;
      } else if (verticalOrigin === VerticalOrigin$1.CENTER) {
        pixelOffset.y += height * 0.5;
      }

      var hotSpot = kmlDoc.createElement("hotSpot");
      hotSpot.setAttribute("x", -pixelOffset.x);
      hotSpot.setAttribute("y", pixelOffset.y);
      hotSpot.setAttribute("xunits", "pixels");
      hotSpot.setAttribute("yunits", "pixels");

      iconStyle.appendChild(hotSpot);
    }

    // We can only specify heading so if axis isn't Z, then we skip the rotation
    // GE treats a heading of zero as no heading but can still point north using a 360 degree angle
    var rotation = valueGetter.get(billboardGraphics.rotation);
    var alignedAxis = valueGetter.get(billboardGraphics.alignedAxis);
    if (defined(rotation) && Cartesian3.equals(Cartesian3.UNIT_Z, alignedAxis)) {
      rotation = CesiumMath.toDegrees(-rotation);
      if (rotation === 0) {
        rotation = 360;
      }

      iconStyle.appendChild(
        createBasicElementWithText(kmlDoc, "heading", rotation)
      );
    }

    return iconStyle;
  }

  function createLineString$1(state, polylineGraphics, geometries, styles) {
    var kmlDoc = state.kmlDoc;
    var ellipsoid = state.ellipsoid;
    var valueGetter = state.valueGetter;

    if (!defined(polylineGraphics)) {
      return;
    }

    var lineStringGeometry = kmlDoc.createElement("LineString");

    // Set altitude mode
    var altitudeMode = kmlDoc.createElement("altitudeMode");
    var clampToGround = valueGetter.get(polylineGraphics.clampToGround, false);
    var altitudeModeText;
    if (clampToGround) {
      lineStringGeometry.appendChild(
        createBasicElementWithText(kmlDoc, "tessellate", true)
      );
      altitudeModeText = kmlDoc.createTextNode("clampToGround");
    } else {
      altitudeModeText = kmlDoc.createTextNode("absolute");
    }
    altitudeMode.appendChild(altitudeModeText);
    lineStringGeometry.appendChild(altitudeMode);

    // Set coordinates
    var positionsProperty = polylineGraphics.positions;
    var cartesians = valueGetter.get(positionsProperty);
    var coordinates = createBasicElementWithText(
      kmlDoc,
      "coordinates",
      getCoordinates(cartesians, ellipsoid)
    );
    lineStringGeometry.appendChild(coordinates);

    // Set draw order
    var zIndex = valueGetter.get(polylineGraphics.zIndex);
    if (clampToGround && defined(zIndex)) {
      lineStringGeometry.appendChild(
        createBasicElementWithText(kmlDoc, "drawOrder", zIndex, gxNamespace)
      );
    }

    geometries.push(lineStringGeometry);

    // Create style
    var lineStyle = kmlDoc.createElement("LineStyle");

    var width = valueGetter.get(polylineGraphics.width);
    if (defined(width)) {
      lineStyle.appendChild(createBasicElementWithText(kmlDoc, "width", width));
    }

    processMaterial(state, polylineGraphics.material, lineStyle);

    styles.push(lineStyle);
  }

  function getRectangleBoundaries(state, rectangleGraphics, extrudedHeight) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;

    var coordinates;
    var height = valueGetter.get(rectangleGraphics.height, 0.0);

    if (extrudedHeight > 0) {
      // We extrude up and KML extrudes down, so if we extrude, set the polygon height to
      // the extruded height so KML will look similar to Cesium
      height = extrudedHeight;
    }

    var coordinatesProperty = rectangleGraphics.coordinates;
    var rectangle = valueGetter.get(coordinatesProperty);

    var coordinateStrings = [];
    var cornerFunction = [
      Rectangle.northeast,
      Rectangle.southeast,
      Rectangle.southwest,
      Rectangle.northwest,
    ];

    for (var i = 0; i < 4; ++i) {
      cornerFunction[i](rectangle, scratchCartographic$a);
      coordinateStrings.push(
        CesiumMath.toDegrees(scratchCartographic$a.longitude) +
          "," +
          CesiumMath.toDegrees(scratchCartographic$a.latitude) +
          "," +
          height
      );
    }

    coordinates = createBasicElementWithText(
      kmlDoc,
      "coordinates",
      coordinateStrings.join(" ")
    );

    var outerBoundaryIs = kmlDoc.createElement("outerBoundaryIs");
    var linearRing = kmlDoc.createElement("LinearRing");
    linearRing.appendChild(coordinates);
    outerBoundaryIs.appendChild(linearRing);

    return [outerBoundaryIs];
  }

  function getLinearRing(state, positions, height, perPositionHeight) {
    var kmlDoc = state.kmlDoc;
    var ellipsoid = state.ellipsoid;

    var coordinateStrings = [];
    var positionCount = positions.length;
    for (var i = 0; i < positionCount; ++i) {
      Cartographic.fromCartesian(positions[i], ellipsoid, scratchCartographic$a);
      coordinateStrings.push(
        CesiumMath.toDegrees(scratchCartographic$a.longitude) +
          "," +
          CesiumMath.toDegrees(scratchCartographic$a.latitude) +
          "," +
          (perPositionHeight ? scratchCartographic$a.height : height)
      );
    }

    var coordinates = createBasicElementWithText(
      kmlDoc,
      "coordinates",
      coordinateStrings.join(" ")
    );
    var linearRing = kmlDoc.createElement("LinearRing");
    linearRing.appendChild(coordinates);

    return linearRing;
  }

  function getPolygonBoundaries(state, polygonGraphics, extrudedHeight) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;

    var height = valueGetter.get(polygonGraphics.height, 0.0);
    var perPositionHeight = valueGetter.get(
      polygonGraphics.perPositionHeight,
      false
    );

    if (!perPositionHeight && extrudedHeight > 0) {
      // We extrude up and KML extrudes down, so if we extrude, set the polygon height to
      // the extruded height so KML will look similar to Cesium
      height = extrudedHeight;
    }

    var boundaries = [];
    var hierarchyProperty = polygonGraphics.hierarchy;
    var hierarchy = valueGetter.get(hierarchyProperty);

    // Polygon hierarchy can sometimes just be an array of positions
    var positions = Array.isArray(hierarchy) ? hierarchy : hierarchy.positions;

    // Polygon boundaries
    var outerBoundaryIs = kmlDoc.createElement("outerBoundaryIs");
    outerBoundaryIs.appendChild(
      getLinearRing(state, positions, height, perPositionHeight)
    );
    boundaries.push(outerBoundaryIs);

    // Hole boundaries
    var holes = hierarchy.holes;
    if (defined(holes)) {
      var holeCount = holes.length;
      for (var i = 0; i < holeCount; ++i) {
        var innerBoundaryIs = kmlDoc.createElement("innerBoundaryIs");
        innerBoundaryIs.appendChild(
          getLinearRing(state, holes[i].positions, height, perPositionHeight)
        );
        boundaries.push(innerBoundaryIs);
      }
    }

    return boundaries;
  }

  function createPolygon$1(state, geometry, geometries, styles, overlays) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;

    if (!defined(geometry)) {
      return;
    }

    // Detect textured quads and use ground overlays instead
    var isRectangle = geometry instanceof RectangleGraphics;
    if (
      isRectangle &&
      valueGetter.getMaterialType(geometry.material) === "Image"
    ) {
      createGroundOverlay(state, geometry, overlays);
      return;
    }

    var polygonGeometry = kmlDoc.createElement("Polygon");

    var extrudedHeight = valueGetter.get(geometry.extrudedHeight, 0.0);
    if (extrudedHeight > 0) {
      polygonGeometry.appendChild(
        createBasicElementWithText(kmlDoc, "extrude", true)
      );
    }

    // Set boundaries
    var boundaries = isRectangle
      ? getRectangleBoundaries(state, geometry, extrudedHeight)
      : getPolygonBoundaries(state, geometry, extrudedHeight);

    var boundaryCount = boundaries.length;
    for (var i = 0; i < boundaryCount; ++i) {
      polygonGeometry.appendChild(boundaries[i]);
    }

    // Set altitude mode
    var altitudeMode = kmlDoc.createElement("altitudeMode");
    altitudeMode.appendChild(getAltitudeMode(state, geometry.heightReference));
    polygonGeometry.appendChild(altitudeMode);

    geometries.push(polygonGeometry);

    // Create style
    var polyStyle = kmlDoc.createElement("PolyStyle");

    var fill = valueGetter.get(geometry.fill, false);
    if (fill) {
      polyStyle.appendChild(createBasicElementWithText(kmlDoc, "fill", fill));
    }

    processMaterial(state, geometry.material, polyStyle);

    var outline = valueGetter.get(geometry.outline, false);
    if (outline) {
      polyStyle.appendChild(
        createBasicElementWithText(kmlDoc, "outline", outline)
      );

      // Outline uses LineStyle
      var lineStyle = kmlDoc.createElement("LineStyle");

      var outlineWidth = valueGetter.get(geometry.outlineWidth, 1.0);
      lineStyle.appendChild(
        createBasicElementWithText(kmlDoc, "width", outlineWidth)
      );

      var outlineColor = valueGetter.getColor(geometry.outlineColor, Color.BLACK);
      lineStyle.appendChild(
        createBasicElementWithText(kmlDoc, "color", outlineColor)
      );
      lineStyle.appendChild(
        createBasicElementWithText(kmlDoc, "colorMode", "normal")
      );

      styles.push(lineStyle);
    }

    styles.push(polyStyle);
  }

  function createGroundOverlay(state, rectangleGraphics, overlays) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;
    var externalFileHandler = state.externalFileHandler;

    var groundOverlay = kmlDoc.createElement("GroundOverlay");

    // Set altitude mode
    var altitudeMode = kmlDoc.createElement("altitudeMode");
    altitudeMode.appendChild(
      getAltitudeMode(state, rectangleGraphics.heightReference)
    );
    groundOverlay.appendChild(altitudeMode);

    var height = valueGetter.get(rectangleGraphics.height);
    if (defined(height)) {
      groundOverlay.appendChild(
        createBasicElementWithText(kmlDoc, "altitude", height)
      );
    }

    var rectangle = valueGetter.get(rectangleGraphics.coordinates);
    var latLonBox = kmlDoc.createElement("LatLonBox");
    latLonBox.appendChild(
      createBasicElementWithText(
        kmlDoc,
        "north",
        CesiumMath.toDegrees(rectangle.north)
      )
    );
    latLonBox.appendChild(
      createBasicElementWithText(
        kmlDoc,
        "south",
        CesiumMath.toDegrees(rectangle.south)
      )
    );
    latLonBox.appendChild(
      createBasicElementWithText(
        kmlDoc,
        "east",
        CesiumMath.toDegrees(rectangle.east)
      )
    );
    latLonBox.appendChild(
      createBasicElementWithText(
        kmlDoc,
        "west",
        CesiumMath.toDegrees(rectangle.west)
      )
    );
    groundOverlay.appendChild(latLonBox);

    // We should only end up here if we have an ImageMaterialProperty
    var material = valueGetter.get(rectangleGraphics.material);
    var href = externalFileHandler.texture(material.image);
    var icon = kmlDoc.createElement("Icon");
    icon.appendChild(createBasicElementWithText(kmlDoc, "href", href));
    groundOverlay.appendChild(icon);

    var color = material.color;
    if (defined(color)) {
      groundOverlay.appendChild(
        createBasicElementWithText(kmlDoc, "color", colorToString(material.color))
      );
    }

    overlays.push(groundOverlay);
  }

  function createModelGeometry(state, modelGraphics) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;
    var externalFileHandler = state.externalFileHandler;

    var modelGeometry = kmlDoc.createElement("Model");

    var scale = valueGetter.get(modelGraphics.scale);
    if (defined(scale)) {
      var scaleElement = kmlDoc.createElement("scale");
      scaleElement.appendChild(createBasicElementWithText(kmlDoc, "x", scale));
      scaleElement.appendChild(createBasicElementWithText(kmlDoc, "y", scale));
      scaleElement.appendChild(createBasicElementWithText(kmlDoc, "z", scale));
      modelGeometry.appendChild(scaleElement);
    }

    var link = kmlDoc.createElement("Link");
    var uri = externalFileHandler.model(modelGraphics, state.time);

    link.appendChild(createBasicElementWithText(kmlDoc, "href", uri));
    modelGeometry.appendChild(link);

    return modelGeometry;
  }

  function createModel$1(state, entity, modelGraphics, geometries, styles) {
    var kmlDoc = state.kmlDoc;
    var ellipsoid = state.ellipsoid;
    var valueGetter = state.valueGetter;

    if (!defined(modelGraphics)) {
      return;
    }

    // If the point isn't constant then create gx:Track or gx:MultiTrack
    var entityPositionProperty = entity.position;
    if (!entityPositionProperty.isConstant) {
      createTracks(state, entity, modelGraphics, geometries, styles);
      return;
    }

    var modelGeometry = createModelGeometry(state, modelGraphics);

    // Set altitude mode
    var altitudeMode = kmlDoc.createElement("altitudeMode");
    altitudeMode.appendChild(
      getAltitudeMode(state, modelGraphics.heightReference)
    );
    modelGeometry.appendChild(altitudeMode);

    valueGetter.get(entityPositionProperty, undefined, scratchCartesian3$b);
    Cartographic.fromCartesian(scratchCartesian3$b, ellipsoid, scratchCartographic$a);
    var location = kmlDoc.createElement("Location");
    location.appendChild(
      createBasicElementWithText(
        kmlDoc,
        "longitude",
        CesiumMath.toDegrees(scratchCartographic$a.longitude)
      )
    );
    location.appendChild(
      createBasicElementWithText(
        kmlDoc,
        "latitude",
        CesiumMath.toDegrees(scratchCartographic$a.latitude)
      )
    );
    location.appendChild(
      createBasicElementWithText(kmlDoc, "altitude", scratchCartographic$a.height)
    );
    modelGeometry.appendChild(location);

    geometries.push(modelGeometry);
  }

  function processMaterial(state, materialProperty, style) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;

    if (!defined(materialProperty)) {
      return;
    }

    var material = valueGetter.get(materialProperty);
    if (!defined(material)) {
      return;
    }

    var color;
    var type = valueGetter.getMaterialType(materialProperty);
    switch (type) {
      case "Image":
        // Image materials are only able to be represented on rectangles, so if we make it
        //  here we can't texture a generic polygon or polyline in KML, so just use white.
        color = colorToString(Color.WHITE);
        break;
      case "Color":
      case "Grid":
      case "PolylineGlow":
      case "PolylineArrow":
      case "PolylineDash":
        color = colorToString(material.color);
        break;
      case "PolylineOutline":
        color = colorToString(material.color);

        var outlineColor = colorToString(material.outlineColor);
        var outlineWidth = material.outlineWidth;
        style.appendChild(
          createBasicElementWithText(
            kmlDoc,
            "outerColor",
            outlineColor,
            gxNamespace
          )
        );
        style.appendChild(
          createBasicElementWithText(
            kmlDoc,
            "outerWidth",
            outlineWidth,
            gxNamespace
          )
        );
        break;
      case "Stripe":
        color = colorToString(material.oddColor);
        break;
    }

    if (defined(color)) {
      style.appendChild(createBasicElementWithText(kmlDoc, "color", color));
      style.appendChild(
        createBasicElementWithText(kmlDoc, "colorMode", "normal")
      );
    }
  }

  function getAltitudeMode(state, heightReferenceProperty) {
    var kmlDoc = state.kmlDoc;
    var valueGetter = state.valueGetter;

    var heightReference = valueGetter.get(
      heightReferenceProperty,
      HeightReference$1.NONE
    );
    var altitudeModeText;
    switch (heightReference) {
      case HeightReference$1.NONE:
        altitudeModeText = kmlDoc.createTextNode("absolute");
        break;
      case HeightReference$1.CLAMP_TO_GROUND:
        altitudeModeText = kmlDoc.createTextNode("clampToGround");
        break;
      case HeightReference$1.RELATIVE_TO_GROUND:
        altitudeModeText = kmlDoc.createTextNode("relativeToGround");
        break;
    }

    return altitudeModeText;
  }

  function getCoordinates(coordinates, ellipsoid) {
    if (!Array.isArray(coordinates)) {
      coordinates = [coordinates];
    }

    var count = coordinates.length;
    var coordinateStrings = [];
    for (var i = 0; i < count; ++i) {
      Cartographic.fromCartesian(coordinates[i], ellipsoid, scratchCartographic$a);
      coordinateStrings.push(
        CesiumMath.toDegrees(scratchCartographic$a.longitude) +
          "," +
          CesiumMath.toDegrees(scratchCartographic$a.latitude) +
          "," +
          scratchCartographic$a.height
      );
    }

    return coordinateStrings.join(" ");
  }

  function createBasicElementWithText(
    kmlDoc,
    elementName,
    elementValue,
    namespace
  ) {
    elementValue = defaultValue(elementValue, "");

    if (typeof elementValue === "boolean") {
      elementValue = elementValue ? "1" : "0";
    }

    // Create element with optional namespace
    var element = defined(namespace)
      ? kmlDoc.createElementNS(namespace, elementName)
      : kmlDoc.createElement(elementName);

    // Wrap value in CDATA section if it contains HTML
    var text =
      elementValue === "string" && elementValue.indexOf("<") !== -1
        ? kmlDoc.createCDATASection(elementValue)
        : kmlDoc.createTextNode(elementValue);

    element.appendChild(text);

    return element;
  }

  function colorToString(color) {
    var result = "";
    var bytes = color.toBytes();
    for (var i = 3; i >= 0; --i) {
      result +=
        bytes[i] < 16 ? "0" + bytes[i].toString(16) : bytes[i].toString(16);
    }

    return result;
  }

  //This file is automatically rebuilt by the Cesium build process.
  var ViewportQuadVS = "attribute vec4 position;\n\
attribute vec2 textureCoordinates;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
gl_Position = position;\n\
v_textureCoordinates = textureCoordinates;\n\
}\n\
";

  /**
   * @private
   */
  function ComputeEngine(context) {
    this._context = context;
  }

  var renderStateScratch;
  var drawCommandScratch = new DrawCommand({
    primitiveType: PrimitiveType$1.TRIANGLES,
  });
  var clearCommandScratch = new ClearCommand({
    color: new Color(0.0, 0.0, 0.0, 0.0),
  });

  function createFramebuffer$1(context, outputTexture) {
    return new Framebuffer({
      context: context,
      colorTextures: [outputTexture],
      destroyAttachments: false,
    });
  }

  function createViewportQuadShader(context, fragmentShaderSource) {
    return ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: ViewportQuadVS,
      fragmentShaderSource: fragmentShaderSource,
      attributeLocations: {
        position: 0,
        textureCoordinates: 1,
      },
    });
  }

  function createRenderState(width, height) {
    if (
      !defined(renderStateScratch) ||
      renderStateScratch.viewport.width !== width ||
      renderStateScratch.viewport.height !== height
    ) {
      renderStateScratch = RenderState.fromCache({
        viewport: new BoundingRectangle(0, 0, width, height),
      });
    }
    return renderStateScratch;
  }

  ComputeEngine.prototype.execute = function (computeCommand) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("computeCommand", computeCommand);
    //>>includeEnd('debug');

    // This may modify the command's resources, so do error checking afterwards
    if (defined(computeCommand.preExecute)) {
      computeCommand.preExecute(computeCommand);
    }

    //>>includeStart('debug', pragmas.debug);
    if (
      !defined(computeCommand.fragmentShaderSource) &&
      !defined(computeCommand.shaderProgram)
    ) {
      throw new DeveloperError(
        "computeCommand.fragmentShaderSource or computeCommand.shaderProgram is required."
      );
    }

    Check.defined("computeCommand.outputTexture", computeCommand.outputTexture);
    //>>includeEnd('debug');

    var outputTexture = computeCommand.outputTexture;
    var width = outputTexture.width;
    var height = outputTexture.height;

    var context = this._context;
    var vertexArray = defined(computeCommand.vertexArray)
      ? computeCommand.vertexArray
      : context.getViewportQuadVertexArray();
    var shaderProgram = defined(computeCommand.shaderProgram)
      ? computeCommand.shaderProgram
      : createViewportQuadShader(context, computeCommand.fragmentShaderSource);
    var framebuffer = createFramebuffer$1(context, outputTexture);
    var renderState = createRenderState(width, height);
    var uniformMap = computeCommand.uniformMap;

    var clearCommand = clearCommandScratch;
    clearCommand.framebuffer = framebuffer;
    clearCommand.renderState = renderState;
    clearCommand.execute(context);

    var drawCommand = drawCommandScratch;
    drawCommand.vertexArray = vertexArray;
    drawCommand.renderState = renderState;
    drawCommand.shaderProgram = shaderProgram;
    drawCommand.uniformMap = uniformMap;
    drawCommand.framebuffer = framebuffer;
    drawCommand.execute(context);

    framebuffer.destroy();

    if (!computeCommand.persists) {
      shaderProgram.destroy();
      if (defined(computeCommand.vertexArray)) {
        vertexArray.destroy();
      }
    }

    if (defined(computeCommand.postExecute)) {
      computeCommand.postExecute(outputTexture);
    }
  };

  ComputeEngine.prototype.isDestroyed = function () {
    return false;
  };

  ComputeEngine.prototype.destroy = function () {
    return destroyObject(this);
  };

  /**
   * The state for a particular rendering pass.  This is used to supplement the state
   * in a command being executed.
   *
   * @private
   * @constructor
   */
  function PassState(context) {
    /**
     * The context used to execute commands for this pass.
     *
     * @type {Context}
     */
    this.context = context;

    /**
     * The framebuffer to render to.  This framebuffer is used unless a {@link DrawCommand}
     * or {@link ClearCommand} explicitly define a framebuffer, which is used for off-screen
     * rendering.
     *
     * @type {Framebuffer}
     * @default undefined
     */
    this.framebuffer = undefined;

    /**
     * When defined, this overrides the blending property of a {@link DrawCommand}'s render state.
     * This is used to, for example, to allow the renderer to turn off blending during the picking pass.
     * <p>
     * When this is <code>undefined</code>, the {@link DrawCommand}'s property is used.
     * </p>
     *
     * @type {Boolean}
     * @default undefined
     */
    this.blendingEnabled = undefined;

    /**
     * When defined, this overrides the scissor test property of a {@link DrawCommand}'s render state.
     * This is used to, for example, to allow the renderer to scissor out the pick region during the picking pass.
     * <p>
     * When this is <code>undefined</code>, the {@link DrawCommand}'s property is used.
     * </p>
     *
     * @type {Object}
     * @default undefined
     */
    this.scissorTest = undefined;

    /**
     * The viewport used when one is not defined by a {@link DrawCommand}'s render state.
     * @type {BoundingRectangle}
     * @default undefined
     */
    this.viewport = undefined;
  }

  /**
   * @private
   */
  function ShaderCache(context) {
    this._context = context;
    this._shaders = {};
    this._numberOfShaders = 0;
    this._shadersToRelease = {};
  }

  Object.defineProperties(ShaderCache.prototype, {
    numberOfShaders: {
      get: function () {
        return this._numberOfShaders;
      },
    },
  });

  /**
       * Returns a shader program from the cache, or creates and caches a new shader program,
       * given the GLSL vertex and fragment shader source and attribute locations.
       * <p>
       * The difference between this and {@link ShaderCache#getShaderProgram}, is this is used to
       * replace an existing reference to a shader program, which is passed as the first argument.
       * </p>
       *
       * @param {Object} options Object with the following properties:
       * @param {ShaderProgram} [options.shaderProgram] The shader program that is being reassigned.
       * @param {String|ShaderSource} options.vertexShaderSource The GLSL source for the vertex shader.
       * @param {String|ShaderSource} options.fragmentShaderSource The GLSL source for the fragment shader.
       * @param {Object} options.attributeLocations Indices for the attribute inputs to the vertex shader.

       * @returns {ShaderProgram} The cached or newly created shader program.
       *
       *
       * @example
       * this._shaderProgram = context.shaderCache.replaceShaderProgram({
       *     shaderProgram : this._shaderProgram,
       *     vertexShaderSource : vs,
       *     fragmentShaderSource : fs,
       *     attributeLocations : attributeLocations
       * });
       *
       * @see ShaderCache#getShaderProgram
       */
  ShaderCache.prototype.replaceShaderProgram = function (options) {
    if (defined(options.shaderProgram)) {
      options.shaderProgram.destroy();
    }

    return this.getShaderProgram(options);
  };

  /**
   * Returns a shader program from the cache, or creates and caches a new shader program,
   * given the GLSL vertex and fragment shader source and attribute locations.
   *
   * @param {Object} options Object with the following properties:
   * @param {String|ShaderSource} options.vertexShaderSource The GLSL source for the vertex shader.
   * @param {String|ShaderSource} options.fragmentShaderSource The GLSL source for the fragment shader.
   * @param {Object} options.attributeLocations Indices for the attribute inputs to the vertex shader.
   *
   * @returns {ShaderProgram} The cached or newly created shader program.
   */
  ShaderCache.prototype.getShaderProgram = function (options) {
    // convert shaders which are provided as strings into ShaderSource objects
    // because ShaderSource handles all the automatic including of built-in functions, etc.

    var vertexShaderSource = options.vertexShaderSource;
    var fragmentShaderSource = options.fragmentShaderSource;
    var attributeLocations = options.attributeLocations;

    if (typeof vertexShaderSource === "string") {
      vertexShaderSource = new ShaderSource({
        sources: [vertexShaderSource],
      });
    }

    if (typeof fragmentShaderSource === "string") {
      fragmentShaderSource = new ShaderSource({
        sources: [fragmentShaderSource],
      });
    }

    var vertexShaderText = vertexShaderSource.createCombinedVertexShader(
      this._context
    );
    var fragmentShaderText = fragmentShaderSource.createCombinedFragmentShader(
      this._context
    );

    var keyword =
      vertexShaderText + fragmentShaderText + JSON.stringify(attributeLocations);
    var cachedShader;

    if (defined(this._shaders[keyword])) {
      cachedShader = this._shaders[keyword];

      // No longer want to release this if it was previously released.
      delete this._shadersToRelease[keyword];
    } else {
      var context = this._context;
      var shaderProgram = new ShaderProgram({
        gl: context._gl,
        logShaderCompilation: context.logShaderCompilation,
        debugShaders: context.debugShaders,
        vertexShaderSource: vertexShaderSource,
        vertexShaderText: vertexShaderText,
        fragmentShaderSource: fragmentShaderSource,
        fragmentShaderText: fragmentShaderText,
        attributeLocations: attributeLocations,
      });

      cachedShader = {
        cache: this,
        shaderProgram: shaderProgram,
        keyword: keyword,
        derivedKeywords: [],
        count: 0,
      };

      // A shader can't be in more than one cache.
      shaderProgram._cachedShader = cachedShader;
      this._shaders[keyword] = cachedShader;
      ++this._numberOfShaders;
    }

    ++cachedShader.count;
    return cachedShader.shaderProgram;
  };

  ShaderCache.prototype.replaceDerivedShaderProgram = function (
    shaderProgram,
    keyword,
    options
  ) {
    var cachedShader = shaderProgram._cachedShader;
    var derivedKeyword = keyword + cachedShader.keyword;
    var cachedDerivedShader = this._shaders[derivedKeyword];
    if (defined(cachedDerivedShader)) {
      destroyShader(this, cachedDerivedShader);
      var index = cachedShader.derivedKeywords.indexOf(keyword);
      if (index > -1) {
        cachedShader.derivedKeywords.splice(index, 1);
      }
    }

    return this.createDerivedShaderProgram(shaderProgram, keyword, options);
  };

  ShaderCache.prototype.getDerivedShaderProgram = function (
    shaderProgram,
    keyword
  ) {
    var cachedShader = shaderProgram._cachedShader;
    var derivedKeyword = keyword + cachedShader.keyword;
    var cachedDerivedShader = this._shaders[derivedKeyword];
    if (!defined(cachedDerivedShader)) {
      return undefined;
    }

    return cachedDerivedShader.shaderProgram;
  };

  ShaderCache.prototype.createDerivedShaderProgram = function (
    shaderProgram,
    keyword,
    options
  ) {
    var cachedShader = shaderProgram._cachedShader;
    var derivedKeyword = keyword + cachedShader.keyword;

    var vertexShaderSource = options.vertexShaderSource;
    var fragmentShaderSource = options.fragmentShaderSource;
    var attributeLocations = options.attributeLocations;

    if (typeof vertexShaderSource === "string") {
      vertexShaderSource = new ShaderSource({
        sources: [vertexShaderSource],
      });
    }

    if (typeof fragmentShaderSource === "string") {
      fragmentShaderSource = new ShaderSource({
        sources: [fragmentShaderSource],
      });
    }

    var context = this._context;

    var vertexShaderText = vertexShaderSource.createCombinedVertexShader(context);
    var fragmentShaderText = fragmentShaderSource.createCombinedFragmentShader(
      context
    );

    var derivedShaderProgram = new ShaderProgram({
      gl: context._gl,
      logShaderCompilation: context.logShaderCompilation,
      debugShaders: context.debugShaders,
      vertexShaderSource: vertexShaderSource,
      vertexShaderText: vertexShaderText,
      fragmentShaderSource: fragmentShaderSource,
      fragmentShaderText: fragmentShaderText,
      attributeLocations: attributeLocations,
    });

    var derivedCachedShader = {
      cache: this,
      shaderProgram: derivedShaderProgram,
      keyword: derivedKeyword,
      derivedKeywords: [],
      count: 0,
    };

    cachedShader.derivedKeywords.push(keyword);
    derivedShaderProgram._cachedShader = derivedCachedShader;
    this._shaders[derivedKeyword] = derivedCachedShader;
    return derivedShaderProgram;
  };

  function destroyShader(cache, cachedShader) {
    var derivedKeywords = cachedShader.derivedKeywords;
    var length = derivedKeywords.length;
    for (var i = 0; i < length; ++i) {
      var keyword = derivedKeywords[i] + cachedShader.keyword;
      var derivedCachedShader = cache._shaders[keyword];
      destroyShader(cache, derivedCachedShader);
    }

    delete cache._shaders[cachedShader.keyword];
    cachedShader.shaderProgram.finalDestroy();
  }

  ShaderCache.prototype.destroyReleasedShaderPrograms = function () {
    var shadersToRelease = this._shadersToRelease;

    for (var keyword in shadersToRelease) {
      if (shadersToRelease.hasOwnProperty(keyword)) {
        var cachedShader = shadersToRelease[keyword];
        destroyShader(this, cachedShader);
        --this._numberOfShaders;
      }
    }

    this._shadersToRelease = {};
  };

  ShaderCache.prototype.releaseShaderProgram = function (shaderProgram) {
    if (defined(shaderProgram)) {
      var cachedShader = shaderProgram._cachedShader;
      if (cachedShader && --cachedShader.count === 0) {
        this._shadersToRelease[cachedShader.keyword] = cachedShader;
      }
    }
  };

  ShaderCache.prototype.isDestroyed = function () {
    return false;
  };

  ShaderCache.prototype.destroy = function () {
    var shaders = this._shaders;
    for (var keyword in shaders) {
      if (shaders.hasOwnProperty(keyword)) {
        shaders[keyword].shaderProgram.finalDestroy();
      }
    }
    return destroyObject(this);
  };

  /**
   * @private
   */
  function TextureCache() {
    this._textures = {};
    this._numberOfTextures = 0;
    this._texturesToRelease = {};
  }

  Object.defineProperties(TextureCache.prototype, {
    numberOfTextures: {
      get: function () {
        return this._numberOfTextures;
      },
    },
  });

  TextureCache.prototype.getTexture = function (keyword) {
    var cachedTexture = this._textures[keyword];
    if (!defined(cachedTexture)) {
      return undefined;
    }

    // No longer want to release this if it was previously released.
    delete this._texturesToRelease[keyword];

    ++cachedTexture.count;
    return cachedTexture.texture;
  };

  TextureCache.prototype.addTexture = function (keyword, texture) {
    var cachedTexture = {
      texture: texture,
      count: 1,
    };

    texture.finalDestroy = texture.destroy;

    var that = this;
    texture.destroy = function () {
      if (--cachedTexture.count === 0) {
        that._texturesToRelease[keyword] = cachedTexture;
      }
    };

    this._textures[keyword] = cachedTexture;
    ++this._numberOfTextures;
  };

  TextureCache.prototype.destroyReleasedTextures = function () {
    var texturesToRelease = this._texturesToRelease;

    for (var keyword in texturesToRelease) {
      if (texturesToRelease.hasOwnProperty(keyword)) {
        var cachedTexture = texturesToRelease[keyword];
        delete this._textures[keyword];
        cachedTexture.texture.finalDestroy();
        --this._numberOfTextures;
      }
    }

    this._texturesToRelease = {};
  };

  TextureCache.prototype.isDestroyed = function () {
    return false;
  };

  TextureCache.prototype.destroy = function () {
    var textures = this._textures;
    for (var keyword in textures) {
      if (textures.hasOwnProperty(keyword)) {
        textures[keyword].texture.finalDestroy();
      }
    }
    return destroyObject(this);
  };

  /**
   * A directional light source that originates from the Sun.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Color} [options.color=Color.WHITE] The light's color.
   * @param {Number} [options.intensity=2.0] The light's intensity.
   *
   * @alias SunLight
   * @constructor
   */
  function SunLight(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    /**
     * The color of the light.
     * @type {Color}
     * @default Color.WHITE
     */
    this.color = Color.clone(defaultValue(options.color, Color.WHITE));

    /**
     * The intensity of the light.
     * @type {Number}
     * @default 2.0
     */
    this.intensity = defaultValue(options.intensity, 2.0);
  }

  /**
   * @private
   * @constructor
   */
  function UniformState() {
    /**
     * @type {Texture}
     */
    this.globeDepthTexture = undefined;
    /**
     * @type {Number}
     */
    this.gamma = undefined;

    this._viewport = new BoundingRectangle();
    this._viewportCartesian4 = new Cartesian4();
    this._viewportDirty = false;
    this._viewportOrthographicMatrix = Matrix4.clone(Matrix4.IDENTITY);
    this._viewportTransformation = Matrix4.clone(Matrix4.IDENTITY);

    this._model = Matrix4.clone(Matrix4.IDENTITY);
    this._view = Matrix4.clone(Matrix4.IDENTITY);
    this._inverseView = Matrix4.clone(Matrix4.IDENTITY);
    this._projection = Matrix4.clone(Matrix4.IDENTITY);
    this._infiniteProjection = Matrix4.clone(Matrix4.IDENTITY);
    this._entireFrustum = new Cartesian2();
    this._currentFrustum = new Cartesian2();
    this._frustumPlanes = new Cartesian4();
    this._farDepthFromNearPlusOne = undefined;
    this._log2FarDepthFromNearPlusOne = undefined;
    this._oneOverLog2FarDepthFromNearPlusOne = undefined;

    this._frameState = undefined;
    this._temeToPseudoFixed = Matrix3.clone(Matrix4.IDENTITY);

    // Derived members
    this._view3DDirty = true;
    this._view3D = new Matrix4();

    this._inverseView3DDirty = true;
    this._inverseView3D = new Matrix4();

    this._inverseModelDirty = true;
    this._inverseModel = new Matrix4();

    this._inverseTransposeModelDirty = true;
    this._inverseTransposeModel = new Matrix3();

    this._viewRotation = new Matrix3();
    this._inverseViewRotation = new Matrix3();

    this._viewRotation3D = new Matrix3();
    this._inverseViewRotation3D = new Matrix3();

    this._inverseProjectionDirty = true;
    this._inverseProjection = new Matrix4();

    this._modelViewDirty = true;
    this._modelView = new Matrix4();

    this._modelView3DDirty = true;
    this._modelView3D = new Matrix4();

    this._modelViewRelativeToEyeDirty = true;
    this._modelViewRelativeToEye = new Matrix4();

    this._inverseModelViewDirty = true;
    this._inverseModelView = new Matrix4();

    this._inverseModelView3DDirty = true;
    this._inverseModelView3D = new Matrix4();

    this._viewProjectionDirty = true;
    this._viewProjection = new Matrix4();

    this._inverseViewProjectionDirty = true;
    this._inverseViewProjection = new Matrix4();

    this._modelViewProjectionDirty = true;
    this._modelViewProjection = new Matrix4();

    this._inverseModelViewProjectionDirty = true;
    this._inverseModelViewProjection = new Matrix4();

    this._modelViewProjectionRelativeToEyeDirty = true;
    this._modelViewProjectionRelativeToEye = new Matrix4();

    this._modelViewInfiniteProjectionDirty = true;
    this._modelViewInfiniteProjection = new Matrix4();

    this._normalDirty = true;
    this._normal = new Matrix3();

    this._normal3DDirty = true;
    this._normal3D = new Matrix3();

    this._inverseNormalDirty = true;
    this._inverseNormal = new Matrix3();

    this._inverseNormal3DDirty = true;
    this._inverseNormal3D = new Matrix3();

    this._encodedCameraPositionMCDirty = true;
    this._encodedCameraPositionMC = new EncodedCartesian3();
    this._cameraPosition = new Cartesian3();

    this._sunPositionWC = new Cartesian3();
    this._sunPositionColumbusView = new Cartesian3();
    this._sunDirectionWC = new Cartesian3();
    this._sunDirectionEC = new Cartesian3();
    this._moonDirectionEC = new Cartesian3();

    this._lightDirectionWC = new Cartesian3();
    this._lightDirectionEC = new Cartesian3();
    this._lightColor = new Cartesian3();
    this._lightColorHdr = new Cartesian3();

    this._pass = undefined;
    this._mode = undefined;
    this._mapProjection = undefined;
    this._ellipsoid = undefined;
    this._cameraDirection = new Cartesian3();
    this._cameraRight = new Cartesian3();
    this._cameraUp = new Cartesian3();
    this._frustum2DWidth = 0.0;
    this._eyeHeight = 0.0;
    this._eyeHeight2D = new Cartesian2();
    this._pixelRatio = 1.0;
    this._orthographicIn3D = false;
    this._backgroundColor = new Color();

    this._brdfLut = undefined;
    this._environmentMap = undefined;

    this._sphericalHarmonicCoefficients = undefined;
    this._specularEnvironmentMaps = undefined;
    this._specularEnvironmentMapsDimensions = new Cartesian2();
    this._specularEnvironmentMapsMaximumLOD = undefined;

    this._fogDensity = undefined;

    this._invertClassificationColor = undefined;

    this._imagerySplitPosition = 0.0;
    this._pixelSizePerMeter = undefined;
    this._geometricToleranceOverMeter = undefined;

    this._minimumDisableDepthTestDistance = undefined;
  }

  Object.defineProperties(UniformState.prototype, {
    /**
     * @memberof UniformState.prototype
     * @type {FrameState}
     * @readonly
     */
    frameState: {
      get: function () {
        return this._frameState;
      },
    },
    /**
     * @memberof UniformState.prototype
     * @type {BoundingRectangle}
     */
    viewport: {
      get: function () {
        return this._viewport;
      },
      set: function (viewport) {
        if (!BoundingRectangle.equals(viewport, this._viewport)) {
          BoundingRectangle.clone(viewport, this._viewport);

          var v = this._viewport;
          var vc = this._viewportCartesian4;
          vc.x = v.x;
          vc.y = v.y;
          vc.z = v.width;
          vc.w = v.height;

          this._viewportDirty = true;
        }
      },
    },

    /**
     * @memberof UniformState.prototype
     * @private
     */
    viewportCartesian4: {
      get: function () {
        return this._viewportCartesian4;
      },
    },

    viewportOrthographic: {
      get: function () {
        cleanViewport(this);
        return this._viewportOrthographicMatrix;
      },
    },

    viewportTransformation: {
      get: function () {
        cleanViewport(this);
        return this._viewportTransformation;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    model: {
      get: function () {
        return this._model;
      },
      set: function (matrix) {
        Matrix4.clone(matrix, this._model);

        this._modelView3DDirty = true;
        this._inverseModelView3DDirty = true;
        this._inverseModelDirty = true;
        this._inverseTransposeModelDirty = true;
        this._modelViewDirty = true;
        this._inverseModelViewDirty = true;
        this._modelViewRelativeToEyeDirty = true;
        this._inverseModelViewDirty = true;
        this._modelViewProjectionDirty = true;
        this._inverseModelViewProjectionDirty = true;
        this._modelViewProjectionRelativeToEyeDirty = true;
        this._modelViewInfiniteProjectionDirty = true;
        this._normalDirty = true;
        this._inverseNormalDirty = true;
        this._normal3DDirty = true;
        this._inverseNormal3DDirty = true;
        this._encodedCameraPositionMCDirty = true;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseModel: {
      get: function () {
        if (this._inverseModelDirty) {
          this._inverseModelDirty = false;

          Matrix4.inverse(this._model, this._inverseModel);
        }

        return this._inverseModel;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @private
     */
    inverseTransposeModel: {
      get: function () {
        var m = this._inverseTransposeModel;
        if (this._inverseTransposeModelDirty) {
          this._inverseTransposeModelDirty = false;

          Matrix4.getMatrix3(this.inverseModel, m);
          Matrix3.transpose(m, m);
        }

        return m;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    view: {
      get: function () {
        return this._view;
      },
    },

    /**
     * The 3D view matrix.  In 3D mode, this is identical to {@link UniformState#view},
     * but in 2D and Columbus View it is a synthetic matrix based on the equivalent position
     * of the camera in the 3D world.
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    view3D: {
      get: function () {
        updateView3D(this);
        return this._view3D;
      },
    },

    /**
     * The 3x3 rotation matrix of the current view matrix ({@link UniformState#view}).
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    viewRotation: {
      get: function () {
        updateView3D(this);
        return this._viewRotation;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    viewRotation3D: {
      get: function () {
        updateView3D(this);
        return this._viewRotation3D;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseView: {
      get: function () {
        return this._inverseView;
      },
    },

    /**
     * the 4x4 inverse-view matrix that transforms from eye to 3D world coordinates.  In 3D mode, this is
     * identical to {@link UniformState#inverseView}, but in 2D and Columbus View it is a synthetic matrix
     * based on the equivalent position of the camera in the 3D world.
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseView3D: {
      get: function () {
        updateInverseView3D(this);
        return this._inverseView3D;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    inverseViewRotation: {
      get: function () {
        return this._inverseViewRotation;
      },
    },

    /**
     * The 3x3 rotation matrix of the current 3D inverse-view matrix ({@link UniformState#inverseView3D}).
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    inverseViewRotation3D: {
      get: function () {
        updateInverseView3D(this);
        return this._inverseViewRotation3D;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    projection: {
      get: function () {
        return this._projection;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseProjection: {
      get: function () {
        cleanInverseProjection(this);
        return this._inverseProjection;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    infiniteProjection: {
      get: function () {
        return this._infiniteProjection;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    modelView: {
      get: function () {
        cleanModelView(this);
        return this._modelView;
      },
    },

    /**
     * The 3D model-view matrix.  In 3D mode, this is equivalent to {@link UniformState#modelView}.  In 2D and
     * Columbus View, however, it is a synthetic matrix based on the equivalent position of the camera in the 3D world.
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    modelView3D: {
      get: function () {
        cleanModelView3D(this);
        return this._modelView3D;
      },
    },

    /**
     * Model-view relative to eye matrix.
     *
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    modelViewRelativeToEye: {
      get: function () {
        cleanModelViewRelativeToEye(this);
        return this._modelViewRelativeToEye;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseModelView: {
      get: function () {
        cleanInverseModelView(this);
        return this._inverseModelView;
      },
    },

    /**
     * The inverse of the 3D model-view matrix.  In 3D mode, this is equivalent to {@link UniformState#inverseModelView}.
     * In 2D and Columbus View, however, it is a synthetic matrix based on the equivalent position of the camera in the 3D world.
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseModelView3D: {
      get: function () {
        cleanInverseModelView3D(this);
        return this._inverseModelView3D;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    viewProjection: {
      get: function () {
        cleanViewProjection(this);
        return this._viewProjection;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseViewProjection: {
      get: function () {
        cleanInverseViewProjection(this);
        return this._inverseViewProjection;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    modelViewProjection: {
      get: function () {
        cleanModelViewProjection(this);
        return this._modelViewProjection;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    inverseModelViewProjection: {
      get: function () {
        cleanInverseModelViewProjection(this);
        return this._inverseModelViewProjection;
      },
    },

    /**
     * Model-view-projection relative to eye matrix.
     *
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    modelViewProjectionRelativeToEye: {
      get: function () {
        cleanModelViewProjectionRelativeToEye(this);
        return this._modelViewProjectionRelativeToEye;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Matrix4}
     */
    modelViewInfiniteProjection: {
      get: function () {
        cleanModelViewInfiniteProjection(this);
        return this._modelViewInfiniteProjection;
      },
    },

    /**
     * A 3x3 normal transformation matrix that transforms normal vectors in model coordinates to
     * eye coordinates.
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    normal: {
      get: function () {
        cleanNormal(this);
        return this._normal;
      },
    },

    /**
     * A 3x3 normal transformation matrix that transforms normal vectors in 3D model
     * coordinates to eye coordinates.  In 3D mode, this is identical to
     * {@link UniformState#normal}, but in 2D and Columbus View it represents the normal transformation
     * matrix as if the camera were at an equivalent location in 3D mode.
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    normal3D: {
      get: function () {
        cleanNormal3D(this);
        return this._normal3D;
      },
    },

    /**
     * An inverse 3x3 normal transformation matrix that transforms normal vectors in model coordinates
     * to eye coordinates.
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    inverseNormal: {
      get: function () {
        cleanInverseNormal(this);
        return this._inverseNormal;
      },
    },

    /**
     * An inverse 3x3 normal transformation matrix that transforms normal vectors in eye coordinates
     * to 3D model coordinates.  In 3D mode, this is identical to
     * {@link UniformState#inverseNormal}, but in 2D and Columbus View it represents the normal transformation
     * matrix as if the camera were at an equivalent location in 3D mode.
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    inverseNormal3D: {
      get: function () {
        cleanInverseNormal3D(this);
        return this._inverseNormal3D;
      },
    },

    /**
     * The near distance (<code>x</code>) and the far distance (<code>y</code>) of the frustum defined by the camera.
     * This is the largest possible frustum, not an individual frustum used for multi-frustum rendering.
     * @memberof UniformState.prototype
     * @type {Cartesian2}
     */
    entireFrustum: {
      get: function () {
        return this._entireFrustum;
      },
    },

    /**
     * The near distance (<code>x</code>) and the far distance (<code>y</code>) of the frustum defined by the camera.
     * This is the individual frustum used for multi-frustum rendering.
     * @memberof UniformState.prototype
     * @type {Cartesian2}
     */
    currentFrustum: {
      get: function () {
        return this._currentFrustum;
      },
    },

    /**
     * The distances to the frustum planes. The top, bottom, left and right distances are
     * the x, y, z, and w components, respectively.
     * @memberof UniformState.prototype
     * @type {Cartesian4}
     */
    frustumPlanes: {
      get: function () {
        return this._frustumPlanes;
      },
    },

    /**
     * The far plane's distance from the near plane, plus 1.0.
     *
     * @memberof UniformState.prototype
     * @type {Number}
     */
    farDepthFromNearPlusOne: {
      get: function () {
        return this._farDepthFromNearPlusOne;
      },
    },

    /**
     * The log2 of {@link UniformState#farDepthFromNearPlusOne}.
     *
     * @memberof UniformState.prototype
     * @type {Number}
     */
    log2FarDepthFromNearPlusOne: {
      get: function () {
        return this._log2FarDepthFromNearPlusOne;
      },
    },

    /**
     * 1.0 divided by {@link UniformState#log2FarDepthFromNearPlusOne}.
     *
     * @memberof UniformState.prototype
     * @type {Number}
     */
    oneOverLog2FarDepthFromNearPlusOne: {
      get: function () {
        return this._oneOverLog2FarDepthFromNearPlusOne;
      },
    },

    /**
     * The height in meters of the eye (camera) above or below the ellipsoid.
     * @memberof UniformState.prototype
     * @type {Number}
     */
    eyeHeight: {
      get: function () {
        return this._eyeHeight;
      },
    },

    /**
     * The height (<code>x</code>) and the height squared (<code>y</code>)
     * in meters of the eye (camera) above the 2D world plane. This uniform is only valid
     * when the {@link SceneMode} is <code>SCENE2D</code>.
     * @memberof UniformState.prototype
     * @type {Cartesian2}
     */
    eyeHeight2D: {
      get: function () {
        return this._eyeHeight2D;
      },
    },

    /**
     * The sun position in 3D world coordinates at the current scene time.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    sunPositionWC: {
      get: function () {
        return this._sunPositionWC;
      },
    },

    /**
     * The sun position in 2D world coordinates at the current scene time.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    sunPositionColumbusView: {
      get: function () {
        return this._sunPositionColumbusView;
      },
    },

    /**
     * A normalized vector to the sun in 3D world coordinates at the current scene time.  Even in 2D or
     * Columbus View mode, this returns the direction to the sun in the 3D scene.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    sunDirectionWC: {
      get: function () {
        return this._sunDirectionWC;
      },
    },

    /**
     * A normalized vector to the sun in eye coordinates at the current scene time.  In 3D mode, this
     * returns the actual vector from the camera position to the sun position.  In 2D and Columbus View, it returns
     * the vector from the equivalent 3D camera position to the position of the sun in the 3D scene.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    sunDirectionEC: {
      get: function () {
        return this._sunDirectionEC;
      },
    },

    /**
     * A normalized vector to the moon in eye coordinates at the current scene time.  In 3D mode, this
     * returns the actual vector from the camera position to the moon position.  In 2D and Columbus View, it returns
     * the vector from the equivalent 3D camera position to the position of the moon in the 3D scene.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    moonDirectionEC: {
      get: function () {
        return this._moonDirectionEC;
      },
    },

    /**
     * A normalized vector to the scene's light source in 3D world coordinates.  Even in 2D or
     * Columbus View mode, this returns the direction to the light in the 3D scene.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    lightDirectionWC: {
      get: function () {
        return this._lightDirectionWC;
      },
    },

    /**
     * A normalized vector to the scene's light source in eye coordinates.  In 3D mode, this
     * returns the actual vector from the camera position to the light.  In 2D and Columbus View, it returns
     * the vector from the equivalent 3D camera position in the 3D scene.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    lightDirectionEC: {
      get: function () {
        return this._lightDirectionEC;
      },
    },

    /**
     * The color of light emitted by the scene's light source. This is equivalent to the light
     * color multiplied by the light intensity limited to a maximum luminance of 1.0 suitable
     * for non-HDR lighting.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    lightColor: {
      get: function () {
        return this._lightColor;
      },
    },

    /**
     * The high dynamic range color of light emitted by the scene's light source. This is equivalent to
     * the light color multiplied by the light intensity suitable for HDR lighting.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    lightColorHdr: {
      get: function () {
        return this._lightColorHdr;
      },
    },

    /**
     * The high bits of the camera position.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    encodedCameraPositionMCHigh: {
      get: function () {
        cleanEncodedCameraPositionMC(this);
        return this._encodedCameraPositionMC.high;
      },
    },

    /**
     * The low bits of the camera position.
     * @memberof UniformState.prototype
     * @type {Cartesian3}
     */
    encodedCameraPositionMCLow: {
      get: function () {
        cleanEncodedCameraPositionMC(this);
        return this._encodedCameraPositionMC.low;
      },
    },

    /**
     * A 3x3 matrix that transforms from True Equator Mean Equinox (TEME) axes to the
     * pseudo-fixed axes at the Scene's current time.
     * @memberof UniformState.prototype
     * @type {Matrix3}
     */
    temeToPseudoFixedMatrix: {
      get: function () {
        return this._temeToPseudoFixed;
      },
    },

    /**
     * Gets the scaling factor for transforming from the canvas
     * pixel space to canvas coordinate space.
     * @memberof UniformState.prototype
     * @type {Number}
     */
    pixelRatio: {
      get: function () {
        return this._pixelRatio;
      },
    },

    /**
     * A scalar used to mix a color with the fog color based on the distance to the camera.
     * @memberof UniformState.prototype
     * @type {Number}
     */
    fogDensity: {
      get: function () {
        return this._fogDensity;
      },
    },

    /**
     * A scalar that represents the geometric tolerance per meter
     * @memberof UniformState.prototype
     * @type {Number}
     */
    geometricToleranceOverMeter: {
      get: function () {
        return this._geometricToleranceOverMeter;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Pass}
     */
    pass: {
      get: function () {
        return this._pass;
      },
    },

    /**
     * The current background color
     * @memberof UniformState.prototype
     * @type {Color}
     */
    backgroundColor: {
      get: function () {
        return this._backgroundColor;
      },
    },

    /**
     * The look up texture used to find the BRDF for a material
     * @memberof UniformState.prototype
     * @type {Texture}
     */
    brdfLut: {
      get: function () {
        return this._brdfLut;
      },
    },

    /**
     * The environment map of the scene
     * @memberof UniformState.prototype
     * @type {CubeMap}
     */
    environmentMap: {
      get: function () {
        return this._environmentMap;
      },
    },

    /**
     * The spherical harmonic coefficients of the scene.
     * @memberof UniformState.prototype
     * @type {Cartesian3[]}
     */
    sphericalHarmonicCoefficients: {
      get: function () {
        return this._sphericalHarmonicCoefficients;
      },
    },

    /**
     * The specular environment map atlas of the scene.
     * @memberof UniformState.prototype
     * @type {Texture}
     */
    specularEnvironmentMaps: {
      get: function () {
        return this._specularEnvironmentMaps;
      },
    },

    /**
     * The dimensions of the specular environment map atlas of the scene.
     * @memberof UniformState.prototype
     * @type {Cartesian2}
     */
    specularEnvironmentMapsDimensions: {
      get: function () {
        return this._specularEnvironmentMapsDimensions;
      },
    },

    /**
     * The maximum level-of-detail of the specular environment map atlas of the scene.
     * @memberof UniformState.prototype
     * @type {Number}
     */
    specularEnvironmentMapsMaximumLOD: {
      get: function () {
        return this._specularEnvironmentMapsMaximumLOD;
      },
    },

    /**
     * @memberof UniformState.prototype
     * @type {Number}
     */
    imagerySplitPosition: {
      get: function () {
        return this._imagerySplitPosition;
      },
    },

    /**
     * The distance from the camera at which to disable the depth test of billboards, labels and points
     * to, for example, prevent clipping against terrain. When set to zero, the depth test should always
     * be applied. When less than zero, the depth test should never be applied.
     *
     * @memberof UniformState.prototype
     * @type {Number}
     */
    minimumDisableDepthTestDistance: {
      get: function () {
        return this._minimumDisableDepthTestDistance;
      },
    },

    /**
     * The highlight color of unclassified 3D Tiles.
     *
     * @memberof UniformState.prototype
     * @type {Color}
     */
    invertClassificationColor: {
      get: function () {
        return this._invertClassificationColor;
      },
    },

    /**
     * Whether or not the current projection is orthographic in 3D.
     *
     * @memberOf UniformState.prototype
     * @type {Boolean}
     */
    orthographicIn3D: {
      get: function () {
        return this._orthographicIn3D;
      },
    },

    /**
     * The current ellipsoid.
     *
     * @memberOf UniformState.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: function () {
        return defaultValue(this._ellipsoid, Ellipsoid.WGS84);
      },
    },
  });

  function setView(uniformState, matrix) {
    Matrix4.clone(matrix, uniformState._view);
    Matrix4.getMatrix3(matrix, uniformState._viewRotation);

    uniformState._view3DDirty = true;
    uniformState._inverseView3DDirty = true;
    uniformState._modelViewDirty = true;
    uniformState._modelView3DDirty = true;
    uniformState._modelViewRelativeToEyeDirty = true;
    uniformState._inverseModelViewDirty = true;
    uniformState._inverseModelView3DDirty = true;
    uniformState._viewProjectionDirty = true;
    uniformState._inverseViewProjectionDirty = true;
    uniformState._modelViewProjectionDirty = true;
    uniformState._modelViewProjectionRelativeToEyeDirty = true;
    uniformState._modelViewInfiniteProjectionDirty = true;
    uniformState._normalDirty = true;
    uniformState._inverseNormalDirty = true;
    uniformState._normal3DDirty = true;
    uniformState._inverseNormal3DDirty = true;
  }

  function setInverseView(uniformState, matrix) {
    Matrix4.clone(matrix, uniformState._inverseView);
    Matrix4.getMatrix3(matrix, uniformState._inverseViewRotation);
  }

  function setProjection(uniformState, matrix) {
    Matrix4.clone(matrix, uniformState._projection);

    uniformState._inverseProjectionDirty = true;
    uniformState._viewProjectionDirty = true;
    uniformState._inverseViewProjectionDirty = true;
    uniformState._modelViewProjectionDirty = true;
    uniformState._modelViewProjectionRelativeToEyeDirty = true;
  }

  function setInfiniteProjection(uniformState, matrix) {
    Matrix4.clone(matrix, uniformState._infiniteProjection);

    uniformState._modelViewInfiniteProjectionDirty = true;
  }

  function setCamera(uniformState, camera) {
    Cartesian3.clone(camera.positionWC, uniformState._cameraPosition);
    Cartesian3.clone(camera.directionWC, uniformState._cameraDirection);
    Cartesian3.clone(camera.rightWC, uniformState._cameraRight);
    Cartesian3.clone(camera.upWC, uniformState._cameraUp);

    var positionCartographic = camera.positionCartographic;
    if (!defined(positionCartographic)) {
      uniformState._eyeHeight = -uniformState._ellipsoid.maximumRadius;
    } else {
      uniformState._eyeHeight = positionCartographic.height;
    }

    uniformState._encodedCameraPositionMCDirty = true;
  }

  var transformMatrix = new Matrix3();
  var sunCartographicScratch = new Cartographic();
  function setSunAndMoonDirections(uniformState, frameState) {
    if (
      !defined(
        Transforms.computeIcrfToFixedMatrix(frameState.time, transformMatrix)
      )
    ) {
      transformMatrix = Transforms.computeTemeToPseudoFixedMatrix(
        frameState.time,
        transformMatrix
      );
    }

    var position = Simon1994PlanetaryPositions.computeSunPositionInEarthInertialFrame(
      frameState.time,
      uniformState._sunPositionWC
    );
    Matrix3.multiplyByVector(transformMatrix, position, position);

    Cartesian3.normalize(position, uniformState._sunDirectionWC);

    position = Matrix3.multiplyByVector(
      uniformState.viewRotation3D,
      position,
      uniformState._sunDirectionEC
    );
    Cartesian3.normalize(position, position);

    position = Simon1994PlanetaryPositions.computeMoonPositionInEarthInertialFrame(
      frameState.time,
      uniformState._moonDirectionEC
    );
    Matrix3.multiplyByVector(transformMatrix, position, position);
    Matrix3.multiplyByVector(uniformState.viewRotation3D, position, position);
    Cartesian3.normalize(position, position);

    var projection = frameState.mapProjection;
    var ellipsoid = projection.ellipsoid;
    var sunCartographic = ellipsoid.cartesianToCartographic(
      uniformState._sunPositionWC,
      sunCartographicScratch
    );
    projection.project(sunCartographic, uniformState._sunPositionColumbusView);
  }

  /**
   * Synchronizes the frustum's state with the camera state.  This is called
   * by the {@link Scene} when rendering to ensure that automatic GLSL uniforms
   * are set to the right value.
   *
   * @param {Object} camera The camera to synchronize with.
   */
  UniformState.prototype.updateCamera = function (camera) {
    setView(this, camera.viewMatrix);
    setInverseView(this, camera.inverseViewMatrix);
    setCamera(this, camera);

    this._entireFrustum.x = camera.frustum.near;
    this._entireFrustum.y = camera.frustum.far;
    this.updateFrustum(camera.frustum);

    this._orthographicIn3D =
      this._mode !== SceneMode$1.SCENE2D &&
      camera.frustum instanceof OrthographicFrustum;
  };

  /**
   * Synchronizes the frustum's state with the uniform state.  This is called
   * by the {@link Scene} when rendering to ensure that automatic GLSL uniforms
   * are set to the right value.
   *
   * @param {Object} frustum The frustum to synchronize with.
   */
  UniformState.prototype.updateFrustum = function (frustum) {
    setProjection(this, frustum.projectionMatrix);
    if (defined(frustum.infiniteProjectionMatrix)) {
      setInfiniteProjection(this, frustum.infiniteProjectionMatrix);
    }
    this._currentFrustum.x = frustum.near;
    this._currentFrustum.y = frustum.far;

    this._farDepthFromNearPlusOne = frustum.far - frustum.near + 1.0;
    this._log2FarDepthFromNearPlusOne = CesiumMath.log2(
      this._farDepthFromNearPlusOne
    );
    this._oneOverLog2FarDepthFromNearPlusOne =
      1.0 / this._log2FarDepthFromNearPlusOne;

    if (defined(frustum._offCenterFrustum)) {
      frustum = frustum._offCenterFrustum;
    }

    this._frustumPlanes.x = frustum.top;
    this._frustumPlanes.y = frustum.bottom;
    this._frustumPlanes.z = frustum.left;
    this._frustumPlanes.w = frustum.right;
  };

  UniformState.prototype.updatePass = function (pass) {
    this._pass = pass;
  };

  var EMPTY_ARRAY = [];
  var defaultLight = new SunLight();

  /**
   * Synchronizes frame state with the uniform state.  This is called
   * by the {@link Scene} when rendering to ensure that automatic GLSL uniforms
   * are set to the right value.
   *
   * @param {FrameState} frameState The frameState to synchronize with.
   */
  UniformState.prototype.update = function (frameState) {
    this._mode = frameState.mode;
    this._mapProjection = frameState.mapProjection;
    this._ellipsoid = frameState.mapProjection.ellipsoid;
    this._pixelRatio = frameState.pixelRatio;

    var camera = frameState.camera;
    this.updateCamera(camera);

    if (frameState.mode === SceneMode$1.SCENE2D) {
      this._frustum2DWidth = camera.frustum.right - camera.frustum.left;
      this._eyeHeight2D.x = this._frustum2DWidth * 0.5;
      this._eyeHeight2D.y = this._eyeHeight2D.x * this._eyeHeight2D.x;
    } else {
      this._frustum2DWidth = 0.0;
      this._eyeHeight2D.x = 0.0;
      this._eyeHeight2D.y = 0.0;
    }

    setSunAndMoonDirections(this, frameState);

    var light = defaultValue(frameState.light, defaultLight);
    if (light instanceof SunLight) {
      this._lightDirectionWC = Cartesian3.clone(
        this._sunDirectionWC,
        this._lightDirectionWC
      );
      this._lightDirectionEC = Cartesian3.clone(
        this._sunDirectionEC,
        this._lightDirectionEC
      );
    } else {
      this._lightDirectionWC = Cartesian3.normalize(
        Cartesian3.negate(light.direction, this._lightDirectionWC),
        this._lightDirectionWC
      );
      this._lightDirectionEC = Matrix3.multiplyByVector(
        this.viewRotation3D,
        this._lightDirectionWC,
        this._lightDirectionEC
      );
    }

    var lightColor = light.color;
    var lightColorHdr = Cartesian3.fromElements(
      lightColor.red,
      lightColor.green,
      lightColor.blue,
      this._lightColorHdr
    );
    lightColorHdr = Cartesian3.multiplyByScalar(
      lightColorHdr,
      light.intensity,
      lightColorHdr
    );
    var maximumComponent = Cartesian3.maximumComponent(lightColorHdr);
    if (maximumComponent > 1.0) {
      Cartesian3.divideByScalar(
        lightColorHdr,
        maximumComponent,
        this._lightColor
      );
    } else {
      Cartesian3.clone(lightColorHdr, this._lightColor);
    }

    var brdfLutGenerator = frameState.brdfLutGenerator;
    var brdfLut = defined(brdfLutGenerator)
      ? brdfLutGenerator.colorTexture
      : undefined;
    this._brdfLut = brdfLut;

    this._environmentMap = defaultValue(
      frameState.environmentMap,
      frameState.context.defaultCubeMap
    );

    // IE 11 doesn't optimize out uniforms that are #ifdef'd out. So undefined values for the spherical harmonic
    // coefficients and specular environment map atlas dimensions cause a crash.
    this._sphericalHarmonicCoefficients = defaultValue(
      frameState.sphericalHarmonicCoefficients,
      EMPTY_ARRAY
    );
    this._specularEnvironmentMaps = frameState.specularEnvironmentMaps;
    this._specularEnvironmentMapsMaximumLOD =
      frameState.specularEnvironmentMapsMaximumLOD;

    if (defined(this._specularEnvironmentMaps)) {
      Cartesian2.clone(
        this._specularEnvironmentMaps.dimensions,
        this._specularEnvironmentMapsDimensions
      );
    }

    this._fogDensity = frameState.fog.density;

    this._invertClassificationColor = frameState.invertClassificationColor;

    this._frameState = frameState;
    this._temeToPseudoFixed = Transforms.computeTemeToPseudoFixedMatrix(
      frameState.time,
      this._temeToPseudoFixed
    );

    // Convert the relative imagerySplitPosition to absolute pixel coordinates
    this._imagerySplitPosition =
      frameState.imagerySplitPosition * frameState.context.drawingBufferWidth;
    var fov = camera.frustum.fov;
    var viewport = this._viewport;
    var pixelSizePerMeter;
    if (defined(fov)) {
      if (viewport.height > viewport.width) {
        pixelSizePerMeter = (Math.tan(0.5 * fov) * 2.0) / viewport.height;
      } else {
        pixelSizePerMeter = (Math.tan(0.5 * fov) * 2.0) / viewport.width;
      }
    } else {
      pixelSizePerMeter = 1.0 / Math.max(viewport.width, viewport.height);
    }

    this._geometricToleranceOverMeter =
      pixelSizePerMeter * frameState.maximumScreenSpaceError;
    Color.clone(frameState.backgroundColor, this._backgroundColor);

    this._minimumDisableDepthTestDistance =
      frameState.minimumDisableDepthTestDistance;
    this._minimumDisableDepthTestDistance *= this._minimumDisableDepthTestDistance;
    if (this._minimumDisableDepthTestDistance === Number.POSITIVE_INFINITY) {
      this._minimumDisableDepthTestDistance = -1.0;
    }
  };

  function cleanViewport(uniformState) {
    if (uniformState._viewportDirty) {
      var v = uniformState._viewport;
      Matrix4.computeOrthographicOffCenter(
        v.x,
        v.x + v.width,
        v.y,
        v.y + v.height,
        0.0,
        1.0,
        uniformState._viewportOrthographicMatrix
      );
      Matrix4.computeViewportTransformation(
        v,
        0.0,
        1.0,
        uniformState._viewportTransformation
      );
      uniformState._viewportDirty = false;
    }
  }

  function cleanInverseProjection(uniformState) {
    if (uniformState._inverseProjectionDirty) {
      uniformState._inverseProjectionDirty = false;

      if (
        uniformState._mode !== SceneMode$1.SCENE2D &&
        uniformState._mode !== SceneMode$1.MORPHING &&
        !uniformState._orthographicIn3D
      ) {
        Matrix4.inverse(
          uniformState._projection,
          uniformState._inverseProjection
        );
      } else {
        Matrix4.clone(Matrix4.ZERO, uniformState._inverseProjection);
      }
    }
  }

  // Derived
  function cleanModelView(uniformState) {
    if (uniformState._modelViewDirty) {
      uniformState._modelViewDirty = false;

      Matrix4.multiplyTransformation(
        uniformState._view,
        uniformState._model,
        uniformState._modelView
      );
    }
  }

  function cleanModelView3D(uniformState) {
    if (uniformState._modelView3DDirty) {
      uniformState._modelView3DDirty = false;

      Matrix4.multiplyTransformation(
        uniformState.view3D,
        uniformState._model,
        uniformState._modelView3D
      );
    }
  }

  function cleanInverseModelView(uniformState) {
    if (uniformState._inverseModelViewDirty) {
      uniformState._inverseModelViewDirty = false;

      Matrix4.inverse(uniformState.modelView, uniformState._inverseModelView);
    }
  }

  function cleanInverseModelView3D(uniformState) {
    if (uniformState._inverseModelView3DDirty) {
      uniformState._inverseModelView3DDirty = false;

      Matrix4.inverse(uniformState.modelView3D, uniformState._inverseModelView3D);
    }
  }

  function cleanViewProjection(uniformState) {
    if (uniformState._viewProjectionDirty) {
      uniformState._viewProjectionDirty = false;

      Matrix4.multiply(
        uniformState._projection,
        uniformState._view,
        uniformState._viewProjection
      );
    }
  }

  function cleanInverseViewProjection(uniformState) {
    if (uniformState._inverseViewProjectionDirty) {
      uniformState._inverseViewProjectionDirty = false;

      Matrix4.inverse(
        uniformState.viewProjection,
        uniformState._inverseViewProjection
      );
    }
  }

  function cleanModelViewProjection(uniformState) {
    if (uniformState._modelViewProjectionDirty) {
      uniformState._modelViewProjectionDirty = false;

      Matrix4.multiply(
        uniformState._projection,
        uniformState.modelView,
        uniformState._modelViewProjection
      );
    }
  }

  function cleanModelViewRelativeToEye(uniformState) {
    if (uniformState._modelViewRelativeToEyeDirty) {
      uniformState._modelViewRelativeToEyeDirty = false;

      var mv = uniformState.modelView;
      var mvRte = uniformState._modelViewRelativeToEye;
      mvRte[0] = mv[0];
      mvRte[1] = mv[1];
      mvRte[2] = mv[2];
      mvRte[3] = mv[3];
      mvRte[4] = mv[4];
      mvRte[5] = mv[5];
      mvRte[6] = mv[6];
      mvRte[7] = mv[7];
      mvRte[8] = mv[8];
      mvRte[9] = mv[9];
      mvRte[10] = mv[10];
      mvRte[11] = mv[11];
      mvRte[12] = 0.0;
      mvRte[13] = 0.0;
      mvRte[14] = 0.0;
      mvRte[15] = mv[15];
    }
  }

  function cleanInverseModelViewProjection(uniformState) {
    if (uniformState._inverseModelViewProjectionDirty) {
      uniformState._inverseModelViewProjectionDirty = false;

      Matrix4.inverse(
        uniformState.modelViewProjection,
        uniformState._inverseModelViewProjection
      );
    }
  }

  function cleanModelViewProjectionRelativeToEye(uniformState) {
    if (uniformState._modelViewProjectionRelativeToEyeDirty) {
      uniformState._modelViewProjectionRelativeToEyeDirty = false;

      Matrix4.multiply(
        uniformState._projection,
        uniformState.modelViewRelativeToEye,
        uniformState._modelViewProjectionRelativeToEye
      );
    }
  }

  function cleanModelViewInfiniteProjection(uniformState) {
    if (uniformState._modelViewInfiniteProjectionDirty) {
      uniformState._modelViewInfiniteProjectionDirty = false;

      Matrix4.multiply(
        uniformState._infiniteProjection,
        uniformState.modelView,
        uniformState._modelViewInfiniteProjection
      );
    }
  }

  function cleanNormal(uniformState) {
    if (uniformState._normalDirty) {
      uniformState._normalDirty = false;

      var m = uniformState._normal;
      Matrix4.getMatrix3(uniformState.inverseModelView, m);
      Matrix3.getRotation(m, m);
      Matrix3.transpose(m, m);
    }
  }

  function cleanNormal3D(uniformState) {
    if (uniformState._normal3DDirty) {
      uniformState._normal3DDirty = false;

      var m = uniformState._normal3D;
      Matrix4.getMatrix3(uniformState.inverseModelView3D, m);
      Matrix3.getRotation(m, m);
      Matrix3.transpose(m, m);
    }
  }

  function cleanInverseNormal(uniformState) {
    if (uniformState._inverseNormalDirty) {
      uniformState._inverseNormalDirty = false;
      Matrix4.getMatrix3(
        uniformState.inverseModelView,
        uniformState._inverseNormal
      );
      Matrix3.getRotation(
        uniformState._inverseNormal,
        uniformState._inverseNormal
      );
    }
  }

  function cleanInverseNormal3D(uniformState) {
    if (uniformState._inverseNormal3DDirty) {
      uniformState._inverseNormal3DDirty = false;
      Matrix4.getMatrix3(
        uniformState.inverseModelView3D,
        uniformState._inverseNormal3D
      );
      Matrix3.getRotation(
        uniformState._inverseNormal3D,
        uniformState._inverseNormal3D
      );
    }
  }

  var cameraPositionMC = new Cartesian3();

  function cleanEncodedCameraPositionMC(uniformState) {
    if (uniformState._encodedCameraPositionMCDirty) {
      uniformState._encodedCameraPositionMCDirty = false;

      Matrix4.multiplyByPoint(
        uniformState.inverseModel,
        uniformState._cameraPosition,
        cameraPositionMC
      );
      EncodedCartesian3.fromCartesian(
        cameraPositionMC,
        uniformState._encodedCameraPositionMC
      );
    }
  }

  var view2Dto3DPScratch = new Cartesian3();
  var view2Dto3DRScratch = new Cartesian3();
  var view2Dto3DUScratch = new Cartesian3();
  var view2Dto3DDScratch = new Cartesian3();
  var view2Dto3DCartographicScratch = new Cartographic();
  var view2Dto3DCartesian3Scratch = new Cartesian3();
  var view2Dto3DMatrix4Scratch = new Matrix4();

  function view2Dto3D(
    position2D,
    direction2D,
    right2D,
    up2D,
    frustum2DWidth,
    mode,
    projection,
    result
  ) {
    // The camera position and directions are expressed in the 2D coordinate system where the Y axis is to the East,
    // the Z axis is to the North, and the X axis is out of the map.  Express them instead in the ENU axes where
    // X is to the East, Y is to the North, and Z is out of the local horizontal plane.
    var p = view2Dto3DPScratch;
    p.x = position2D.y;
    p.y = position2D.z;
    p.z = position2D.x;

    var r = view2Dto3DRScratch;
    r.x = right2D.y;
    r.y = right2D.z;
    r.z = right2D.x;

    var u = view2Dto3DUScratch;
    u.x = up2D.y;
    u.y = up2D.z;
    u.z = up2D.x;

    var d = view2Dto3DDScratch;
    d.x = direction2D.y;
    d.y = direction2D.z;
    d.z = direction2D.x;

    // In 2D, the camera height is always 12.7 million meters.
    // The apparent height is equal to half the frustum width.
    if (mode === SceneMode$1.SCENE2D) {
      p.z = frustum2DWidth * 0.5;
    }

    // Compute the equivalent camera position in the real (3D) world.
    // In 2D and Columbus View, the camera can travel outside the projection, and when it does so
    // there's not really any corresponding location in the real world.  So clamp the unprojected
    // longitude and latitude to their valid ranges.
    var cartographic = projection.unproject(p, view2Dto3DCartographicScratch);
    cartographic.longitude = CesiumMath.clamp(
      cartographic.longitude,
      -Math.PI,
      Math.PI
    );
    cartographic.latitude = CesiumMath.clamp(
      cartographic.latitude,
      -CesiumMath.PI_OVER_TWO,
      CesiumMath.PI_OVER_TWO
    );
    var ellipsoid = projection.ellipsoid;
    var position3D = ellipsoid.cartographicToCartesian(
      cartographic,
      view2Dto3DCartesian3Scratch
    );

    // Compute the rotation from the local ENU at the real world camera position to the fixed axes.
    var enuToFixed = Transforms.eastNorthUpToFixedFrame(
      position3D,
      ellipsoid,
      view2Dto3DMatrix4Scratch
    );

    // Transform each camera direction to the fixed axes.
    Matrix4.multiplyByPointAsVector(enuToFixed, r, r);
    Matrix4.multiplyByPointAsVector(enuToFixed, u, u);
    Matrix4.multiplyByPointAsVector(enuToFixed, d, d);

    // Compute the view matrix based on the new fixed-frame camera position and directions.
    if (!defined(result)) {
      result = new Matrix4();
    }

    result[0] = r.x;
    result[1] = u.x;
    result[2] = -d.x;
    result[3] = 0.0;
    result[4] = r.y;
    result[5] = u.y;
    result[6] = -d.y;
    result[7] = 0.0;
    result[8] = r.z;
    result[9] = u.z;
    result[10] = -d.z;
    result[11] = 0.0;
    result[12] = -Cartesian3.dot(r, position3D);
    result[13] = -Cartesian3.dot(u, position3D);
    result[14] = Cartesian3.dot(d, position3D);
    result[15] = 1.0;

    return result;
  }

  function updateView3D(that) {
    if (that._view3DDirty) {
      if (that._mode === SceneMode$1.SCENE3D) {
        Matrix4.clone(that._view, that._view3D);
      } else {
        view2Dto3D(
          that._cameraPosition,
          that._cameraDirection,
          that._cameraRight,
          that._cameraUp,
          that._frustum2DWidth,
          that._mode,
          that._mapProjection,
          that._view3D
        );
      }
      Matrix4.getMatrix3(that._view3D, that._viewRotation3D);
      that._view3DDirty = false;
    }
  }

  function updateInverseView3D(that) {
    if (that._inverseView3DDirty) {
      Matrix4.inverseTransformation(that.view3D, that._inverseView3D);
      Matrix4.getMatrix3(that._inverseView3D, that._inverseViewRotation3D);
      that._inverseView3DDirty = false;
    }
  }

  function errorToString(gl, error) {
    var message = "WebGL Error:  ";
    switch (error) {
      case gl.INVALID_ENUM:
        message += "INVALID_ENUM";
        break;
      case gl.INVALID_VALUE:
        message += "INVALID_VALUE";
        break;
      case gl.INVALID_OPERATION:
        message += "INVALID_OPERATION";
        break;
      case gl.OUT_OF_MEMORY:
        message += "OUT_OF_MEMORY";
        break;
      case gl.CONTEXT_LOST_WEBGL:
        message += "CONTEXT_LOST_WEBGL lost";
        break;
      default:
        message += "Unknown (" + error + ")";
    }

    return message;
  }

  function createErrorMessage(gl, glFunc, glFuncArguments, error) {
    var message = errorToString(gl, error) + ": " + glFunc.name + "(";

    for (var i = 0; i < glFuncArguments.length; ++i) {
      if (i !== 0) {
        message += ", ";
      }
      message += glFuncArguments[i];
    }
    message += ");";

    return message;
  }

  function throwOnError(gl, glFunc, glFuncArguments) {
    var error = gl.getError();
    if (error !== gl.NO_ERROR) {
      throw new RuntimeError(
        createErrorMessage(gl, glFunc, glFuncArguments, error)
      );
    }
  }

  function makeGetterSetter(gl, propertyName, logFunction) {
    return {
      get: function () {
        var value = gl[propertyName];
        logFunction(gl, "get: " + propertyName, value);
        return gl[propertyName];
      },
      set: function (value) {
        gl[propertyName] = value;
        logFunction(gl, "set: " + propertyName, value);
      },
    };
  }

  function wrapGL(gl, logFunction) {
    if (!defined(logFunction)) {
      return gl;
    }

    function wrapFunction(property) {
      return function () {
        var result = property.apply(gl, arguments);
        logFunction(gl, property, arguments);
        return result;
      };
    }

    var glWrapper = {};

    // JavaScript linters normally demand that a for..in loop must directly contain an if,
    // but in our loop below, we actually intend to iterate all properties, including
    // those in the prototype.
    /*eslint-disable guard-for-in*/
    for (var propertyName in gl) {
      var property = gl[propertyName];

      // wrap any functions we encounter, otherwise just copy the property to the wrapper.
      if (property instanceof Function) {
        glWrapper[propertyName] = wrapFunction(property);
      } else {
        Object.defineProperty(
          glWrapper,
          propertyName,
          makeGetterSetter(gl, propertyName, logFunction)
        );
      }
    }
    /*eslint-enable guard-for-in*/

    return glWrapper;
  }

  function getExtension(gl, names) {
    var length = names.length;
    for (var i = 0; i < length; ++i) {
      var extension = gl.getExtension(names[i]);
      if (extension) {
        return extension;
      }
    }

    return undefined;
  }

  /**
   * @private
   * @constructor
   */
  function Context(canvas, options) {
    // this check must use typeof, not defined, because defined doesn't work with undeclared variables.
    if (typeof WebGLRenderingContext === "undefined") {
      throw new RuntimeError(
        "The browser does not support WebGL.  Visit http://get.webgl.org."
      );
    }

    //>>includeStart('debug', pragmas.debug);
    Check.defined("canvas", canvas);
    //>>includeEnd('debug');

    this._canvas = canvas;

    options = clone(options, true);
    // Don't use defaultValue.EMPTY_OBJECT here because the options object gets modified in the next line.
    options = defaultValue(options, {});
    options.allowTextureFilterAnisotropic = defaultValue(
      options.allowTextureFilterAnisotropic,
      true
    );
    var webglOptions = defaultValue(options.webgl, {});

    // Override select WebGL defaults
    webglOptions.alpha = defaultValue(webglOptions.alpha, false); // WebGL default is true
    webglOptions.stencil = defaultValue(webglOptions.stencil, true); // WebGL default is false

    var requestWebgl2 =
      defaultValue(options.requestWebgl2, false) &&
      typeof WebGL2RenderingContext !== "undefined";
    var webgl2 = false;

    var glContext;
    var getWebGLStub = options.getWebGLStub;

    if (!defined(getWebGLStub)) {
      if (requestWebgl2) {
        glContext =
          canvas.getContext("webgl2", webglOptions) ||
          canvas.getContext("experimental-webgl2", webglOptions) ||
          undefined;
        if (defined(glContext)) {
          webgl2 = true;
        }
      }
      if (!defined(glContext)) {
        glContext =
          canvas.getContext("webgl", webglOptions) ||
          canvas.getContext("experimental-webgl", webglOptions) ||
          undefined;
      }
      if (!defined(glContext)) {
        throw new RuntimeError(
          "The browser supports WebGL, but initialization failed."
        );
      }
    } else {
      // Use WebGL stub when requested for unit tests
      glContext = getWebGLStub(canvas, webglOptions);
    }

    this._originalGLContext = glContext;
    this._gl = glContext;
    this._webgl2 = webgl2;
    this._id = createGuid();

    // Validation and logging disabled by default for speed.
    this.validateFramebuffer = false;
    this.validateShaderProgram = false;
    this.logShaderCompilation = false;

    this._throwOnWebGLError = false;

    this._shaderCache = new ShaderCache(this);
    this._textureCache = new TextureCache();

    var gl = glContext;

    this._stencilBits = gl.getParameter(gl.STENCIL_BITS);

    ContextLimits._maximumCombinedTextureImageUnits = gl.getParameter(
      gl.MAX_COMBINED_TEXTURE_IMAGE_UNITS
    ); // min: 8
    ContextLimits._maximumCubeMapSize = gl.getParameter(
      gl.MAX_CUBE_MAP_TEXTURE_SIZE
    ); // min: 16
    ContextLimits._maximumFragmentUniformVectors = gl.getParameter(
      gl.MAX_FRAGMENT_UNIFORM_VECTORS
    ); // min: 16
    ContextLimits._maximumTextureImageUnits = gl.getParameter(
      gl.MAX_TEXTURE_IMAGE_UNITS
    ); // min: 8
    ContextLimits._maximumRenderbufferSize = gl.getParameter(
      gl.MAX_RENDERBUFFER_SIZE
    ); // min: 1
    ContextLimits._maximumTextureSize = gl.getParameter(gl.MAX_TEXTURE_SIZE); // min: 64
    ContextLimits._maximumVaryingVectors = gl.getParameter(
      gl.MAX_VARYING_VECTORS
    ); // min: 8
    ContextLimits._maximumVertexAttributes = gl.getParameter(
      gl.MAX_VERTEX_ATTRIBS
    ); // min: 8
    ContextLimits._maximumVertexTextureImageUnits = gl.getParameter(
      gl.MAX_VERTEX_TEXTURE_IMAGE_UNITS
    ); // min: 0
    ContextLimits._maximumVertexUniformVectors = gl.getParameter(
      gl.MAX_VERTEX_UNIFORM_VECTORS
    ); // min: 128

    var aliasedLineWidthRange = gl.getParameter(gl.ALIASED_LINE_WIDTH_RANGE); // must include 1
    ContextLimits._minimumAliasedLineWidth = aliasedLineWidthRange[0];
    ContextLimits._maximumAliasedLineWidth = aliasedLineWidthRange[1];

    var aliasedPointSizeRange = gl.getParameter(gl.ALIASED_POINT_SIZE_RANGE); // must include 1
    ContextLimits._minimumAliasedPointSize = aliasedPointSizeRange[0];
    ContextLimits._maximumAliasedPointSize = aliasedPointSizeRange[1];

    var maximumViewportDimensions = gl.getParameter(gl.MAX_VIEWPORT_DIMS);
    ContextLimits._maximumViewportWidth = maximumViewportDimensions[0];
    ContextLimits._maximumViewportHeight = maximumViewportDimensions[1];

    var highpFloat = gl.getShaderPrecisionFormat(
      gl.FRAGMENT_SHADER,
      gl.HIGH_FLOAT
    );
    ContextLimits._highpFloatSupported = highpFloat.precision !== 0;
    var highpInt = gl.getShaderPrecisionFormat(gl.FRAGMENT_SHADER, gl.HIGH_INT);
    ContextLimits._highpIntSupported = highpInt.rangeMax !== 0;

    this._antialias = gl.getContextAttributes().antialias;

    // Query and initialize extensions
    this._standardDerivatives = !!getExtension(gl, ["OES_standard_derivatives"]);
    this._blendMinmax = !!getExtension(gl, ["EXT_blend_minmax"]);
    this._elementIndexUint = !!getExtension(gl, ["OES_element_index_uint"]);
    this._depthTexture = !!getExtension(gl, [
      "WEBGL_depth_texture",
      "WEBKIT_WEBGL_depth_texture",
    ]);
    this._fragDepth = !!getExtension(gl, ["EXT_frag_depth"]);
    this._debugShaders = getExtension(gl, ["WEBGL_debug_shaders"]);

    this._textureFloat = !!getExtension(gl, ["OES_texture_float"]);
    this._textureHalfFloat = !!getExtension(gl, ["OES_texture_half_float"]);

    this._textureFloatLinear = !!getExtension(gl, ["OES_texture_float_linear"]);
    this._textureHalfFloatLinear = !!getExtension(gl, [
      "OES_texture_half_float_linear",
    ]);

    this._colorBufferFloat = !!getExtension(gl, [
      "EXT_color_buffer_float",
      "WEBGL_color_buffer_float",
    ]);
    this._floatBlend = !!getExtension(gl, ["EXT_float_blend"]);
    this._colorBufferHalfFloat = !!getExtension(gl, [
      "EXT_color_buffer_half_float",
    ]);

    this._s3tc = !!getExtension(gl, [
      "WEBGL_compressed_texture_s3tc",
      "MOZ_WEBGL_compressed_texture_s3tc",
      "WEBKIT_WEBGL_compressed_texture_s3tc",
    ]);
    this._pvrtc = !!getExtension(gl, [
      "WEBGL_compressed_texture_pvrtc",
      "WEBKIT_WEBGL_compressed_texture_pvrtc",
    ]);
    this._etc1 = !!getExtension(gl, ["WEBGL_compressed_texture_etc1"]);

    var textureFilterAnisotropic = options.allowTextureFilterAnisotropic
      ? getExtension(gl, [
          "EXT_texture_filter_anisotropic",
          "WEBKIT_EXT_texture_filter_anisotropic",
        ])
      : undefined;
    this._textureFilterAnisotropic = textureFilterAnisotropic;
    ContextLimits._maximumTextureFilterAnisotropy = defined(
      textureFilterAnisotropic
    )
      ? gl.getParameter(textureFilterAnisotropic.MAX_TEXTURE_MAX_ANISOTROPY_EXT)
      : 1.0;

    var glCreateVertexArray;
    var glBindVertexArray;
    var glDeleteVertexArray;

    var glDrawElementsInstanced;
    var glDrawArraysInstanced;
    var glVertexAttribDivisor;

    var glDrawBuffers;

    var vertexArrayObject;
    var instancedArrays;
    var drawBuffers;

    if (webgl2) {
      var that = this;

      glCreateVertexArray = function () {
        return that._gl.createVertexArray();
      };
      glBindVertexArray = function (vao) {
        that._gl.bindVertexArray(vao);
      };
      glDeleteVertexArray = function (vao) {
        that._gl.deleteVertexArray(vao);
      };

      glDrawElementsInstanced = function (
        mode,
        count,
        type,
        offset,
        instanceCount
      ) {
        gl.drawElementsInstanced(mode, count, type, offset, instanceCount);
      };
      glDrawArraysInstanced = function (mode, first, count, instanceCount) {
        gl.drawArraysInstanced(mode, first, count, instanceCount);
      };
      glVertexAttribDivisor = function (index, divisor) {
        gl.vertexAttribDivisor(index, divisor);
      };

      glDrawBuffers = function (buffers) {
        gl.drawBuffers(buffers);
      };
    } else {
      vertexArrayObject = getExtension(gl, ["OES_vertex_array_object"]);
      if (defined(vertexArrayObject)) {
        glCreateVertexArray = function () {
          return vertexArrayObject.createVertexArrayOES();
        };
        glBindVertexArray = function (vertexArray) {
          vertexArrayObject.bindVertexArrayOES(vertexArray);
        };
        glDeleteVertexArray = function (vertexArray) {
          vertexArrayObject.deleteVertexArrayOES(vertexArray);
        };
      }

      instancedArrays = getExtension(gl, ["ANGLE_instanced_arrays"]);
      if (defined(instancedArrays)) {
        glDrawElementsInstanced = function (
          mode,
          count,
          type,
          offset,
          instanceCount
        ) {
          instancedArrays.drawElementsInstancedANGLE(
            mode,
            count,
            type,
            offset,
            instanceCount
          );
        };
        glDrawArraysInstanced = function (mode, first, count, instanceCount) {
          instancedArrays.drawArraysInstancedANGLE(
            mode,
            first,
            count,
            instanceCount
          );
        };
        glVertexAttribDivisor = function (index, divisor) {
          instancedArrays.vertexAttribDivisorANGLE(index, divisor);
        };
      }

      drawBuffers = getExtension(gl, ["WEBGL_draw_buffers"]);
      if (defined(drawBuffers)) {
        glDrawBuffers = function (buffers) {
          drawBuffers.drawBuffersWEBGL(buffers);
        };
      }
    }

    this.glCreateVertexArray = glCreateVertexArray;
    this.glBindVertexArray = glBindVertexArray;
    this.glDeleteVertexArray = glDeleteVertexArray;

    this.glDrawElementsInstanced = glDrawElementsInstanced;
    this.glDrawArraysInstanced = glDrawArraysInstanced;
    this.glVertexAttribDivisor = glVertexAttribDivisor;

    this.glDrawBuffers = glDrawBuffers;

    this._vertexArrayObject = !!vertexArrayObject;
    this._instancedArrays = !!instancedArrays;
    this._drawBuffers = !!drawBuffers;

    ContextLimits._maximumDrawBuffers = this.drawBuffers
      ? gl.getParameter(WebGLConstants$1.MAX_DRAW_BUFFERS)
      : 1;
    ContextLimits._maximumColorAttachments = this.drawBuffers
      ? gl.getParameter(WebGLConstants$1.MAX_COLOR_ATTACHMENTS)
      : 1;

    this._clearColor = new Color(0.0, 0.0, 0.0, 0.0);
    this._clearDepth = 1.0;
    this._clearStencil = 0;

    var us = new UniformState();
    var ps = new PassState(this);
    var rs = RenderState.fromCache();

    this._defaultPassState = ps;
    this._defaultRenderState = rs;
    this._defaultTexture = undefined;
    this._defaultCubeMap = undefined;

    this._us = us;
    this._currentRenderState = rs;
    this._currentPassState = ps;
    this._currentFramebuffer = undefined;
    this._maxFrameTextureUnitIndex = 0;

    // Vertex attribute divisor state cache. Workaround for ANGLE (also look at VertexArray.setVertexAttribDivisor)
    this._vertexAttribDivisors = [];
    this._previousDrawInstanced = false;
    for (var i = 0; i < ContextLimits._maximumVertexAttributes; i++) {
      this._vertexAttribDivisors.push(0);
    }

    this._pickObjects = {};
    this._nextPickColor = new Uint32Array(1);

    /**
     * @example
     * {
     *   webgl : {
     *     alpha : false,
     *     depth : true,
     *     stencil : false,
     *     antialias : true,
     *     premultipliedAlpha : true,
     *     preserveDrawingBuffer : false,
     *     failIfMajorPerformanceCaveat : true
     *   },
     *   allowTextureFilterAnisotropic : true
     * }
     */
    this.options = options;

    /**
     * A cache of objects tied to this context.  Just before the Context is destroyed,
     * <code>destroy</code> will be invoked on each object in this object literal that has
     * such a method.  This is useful for caching any objects that might otherwise
     * be stored globally, except they're tied to a particular context, and to manage
     * their lifetime.
     *
     * @type {Object}
     */
    this.cache = {};

    RenderState.apply(gl, rs, ps);
  }

  var defaultFramebufferMarker = {};

  Object.defineProperties(Context.prototype, {
    id: {
      get: function () {
        return this._id;
      },
    },
    webgl2: {
      get: function () {
        return this._webgl2;
      },
    },
    canvas: {
      get: function () {
        return this._canvas;
      },
    },
    shaderCache: {
      get: function () {
        return this._shaderCache;
      },
    },
    textureCache: {
      get: function () {
        return this._textureCache;
      },
    },
    uniformState: {
      get: function () {
        return this._us;
      },
    },

    /**
     * The number of stencil bits per pixel in the default bound framebuffer.  The minimum is eight bits.
     * @memberof Context.prototype
     * @type {Number}
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>STENCIL_BITS</code>.
     */
    stencilBits: {
      get: function () {
        return this._stencilBits;
      },
    },

    /**
     * <code>true</code> if the WebGL context supports stencil buffers.
     * Stencil buffers are not supported by all systems.
     * @memberof Context.prototype
     * @type {Boolean}
     */
    stencilBuffer: {
      get: function () {
        return this._stencilBits >= 8;
      },
    },

    /**
     * <code>true</code> if the WebGL context supports antialiasing.  By default
     * antialiasing is requested, but it is not supported by all systems.
     * @memberof Context.prototype
     * @type {Boolean}
     */
    antialias: {
      get: function () {
        return this._antialias;
      },
    },

    /**
     * <code>true</code> if the OES_standard_derivatives extension is supported.  This
     * extension provides access to <code>dFdx</code>, <code>dFdy</code>, and <code>fwidth</code>
     * functions from GLSL.  A shader using these functions still needs to explicitly enable the
     * extension with <code>#extension GL_OES_standard_derivatives : enable</code>.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link http://www.khronos.org/registry/gles/extensions/OES/OES_standard_derivatives.txt|OES_standard_derivatives}
     */
    standardDerivatives: {
      get: function () {
        return this._standardDerivatives || this._webgl2;
      },
    },

    /**
     * <code>true</code> if the EXT_float_blend extension is supported. This
     * extension enables blending with 32-bit float values.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/EXT_float_blend/}
     */
    floatBlend: {
      get: function () {
        return this._floatBlend;
      },
    },

    /**
     * <code>true</code> if the EXT_blend_minmax extension is supported.  This
     * extension extends blending capabilities by adding two new blend equations:
     * the minimum or maximum color components of the source and destination colors.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/EXT_blend_minmax/}
     */
    blendMinmax: {
      get: function () {
        return this._blendMinmax || this._webgl2;
      },
    },

    /**
     * <code>true</code> if the OES_element_index_uint extension is supported.  This
     * extension allows the use of unsigned int indices, which can improve performance by
     * eliminating batch breaking caused by unsigned short indices.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link http://www.khronos.org/registry/webgl/extensions/OES_element_index_uint/|OES_element_index_uint}
     */
    elementIndexUint: {
      get: function () {
        return this._elementIndexUint || this._webgl2;
      },
    },

    /**
     * <code>true</code> if WEBGL_depth_texture is supported.  This extension provides
     * access to depth textures that, for example, can be attached to framebuffers for shadow mapping.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link http://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/|WEBGL_depth_texture}
     */
    depthTexture: {
      get: function () {
        return this._depthTexture || this._webgl2;
      },
    },

    /**
     * <code>true</code> if OES_texture_float is supported. This extension provides
     * access to floating point textures that, for example, can be attached to framebuffers for high dynamic range.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/OES_texture_float/}
     */
    floatingPointTexture: {
      get: function () {
        return this._webgl2 || this._textureFloat;
      },
    },

    /**
     * <code>true</code> if OES_texture_half_float is supported. This extension provides
     * access to floating point textures that, for example, can be attached to framebuffers for high dynamic range.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/OES_texture_float/}
     */
    halfFloatingPointTexture: {
      get: function () {
        return this._webgl2 || this._textureHalfFloat;
      },
    },

    /**
     * <code>true</code> if OES_texture_float_linear is supported. This extension provides
     * access to linear sampling methods for minification and magnification filters of floating-point textures.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/OES_texture_float_linear/}
     */
    textureFloatLinear: {
      get: function () {
        return this._textureFloatLinear;
      },
    },

    /**
     * <code>true</code> if OES_texture_half_float_linear is supported. This extension provides
     * access to linear sampling methods for minification and magnification filters of half floating-point textures.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/OES_texture_half_float_linear/}
     */
    textureHalfFloatLinear: {
      get: function () {
        return (
          (this._webgl2 && this._textureFloatLinear) ||
          (!this._webgl2 && this._textureHalfFloatLinear)
        );
      },
    },

    /**
     * <code>true</code> if EXT_texture_filter_anisotropic is supported. This extension provides
     * access to anisotropic filtering for textured surfaces at an oblique angle from the viewer.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/EXT_texture_filter_anisotropic/}
     */
    textureFilterAnisotropic: {
      get: function () {
        return !!this._textureFilterAnisotropic;
      },
    },

    /**
     * <code>true</code> if WEBGL_texture_compression_s3tc is supported.  This extension provides
     * access to DXT compressed textures.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_s3tc/}
     */
    s3tc: {
      get: function () {
        return this._s3tc;
      },
    },

    /**
     * <code>true</code> if WEBGL_texture_compression_pvrtc is supported.  This extension provides
     * access to PVR compressed textures.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_pvrtc/}
     */
    pvrtc: {
      get: function () {
        return this._pvrtc;
      },
    },

    /**
     * <code>true</code> if WEBGL_texture_compression_etc1 is supported.  This extension provides
     * access to ETC1 compressed textures.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_etc1/}
     */
    etc1: {
      get: function () {
        return this._etc1;
      },
    },

    /**
     * <code>true</code> if the OES_vertex_array_object extension is supported.  This
     * extension can improve performance by reducing the overhead of switching vertex arrays.
     * When enabled, this extension is automatically used by {@link VertexArray}.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link http://www.khronos.org/registry/webgl/extensions/OES_vertex_array_object/|OES_vertex_array_object}
     */
    vertexArrayObject: {
      get: function () {
        return this._vertexArrayObject || this._webgl2;
      },
    },

    /**
     * <code>true</code> if the EXT_frag_depth extension is supported.  This
     * extension provides access to the <code>gl_FragDepthEXT</code> built-in output variable
     * from GLSL fragment shaders.  A shader using these functions still needs to explicitly enable the
     * extension with <code>#extension GL_EXT_frag_depth : enable</code>.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link http://www.khronos.org/registry/webgl/extensions/EXT_frag_depth/|EXT_frag_depth}
     */
    fragmentDepth: {
      get: function () {
        return this._fragDepth || this._webgl2;
      },
    },

    /**
     * <code>true</code> if the ANGLE_instanced_arrays extension is supported.  This
     * extension provides access to instanced rendering.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/ANGLE_instanced_arrays}
     */
    instancedArrays: {
      get: function () {
        return this._instancedArrays || this._webgl2;
      },
    },

    /**
     * <code>true</code> if the EXT_color_buffer_float extension is supported.  This
     * extension makes the gl.RGBA32F format color renderable.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/WEBGL_color_buffer_float/}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/EXT_color_buffer_float/}
     */
    colorBufferFloat: {
      get: function () {
        return this._colorBufferFloat;
      },
    },

    /**
     * <code>true</code> if the EXT_color_buffer_half_float extension is supported.  This
     * extension makes the format gl.RGBA16F format color renderable.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/EXT_color_buffer_half_float/}
     * @see {@link https://www.khronos.org/registry/webgl/extensions/EXT_color_buffer_float/}
     */
    colorBufferHalfFloat: {
      get: function () {
        return (
          (this._webgl2 && this._colorBufferFloat) ||
          (!this._webgl2 && this._colorBufferHalfFloat)
        );
      },
    },

    /**
     * <code>true</code> if the WEBGL_draw_buffers extension is supported. This
     * extensions provides support for multiple render targets. The framebuffer object can have mutiple
     * color attachments and the GLSL fragment shader can write to the built-in output array <code>gl_FragData</code>.
     * A shader using this feature needs to explicitly enable the extension with
     * <code>#extension GL_EXT_draw_buffers : enable</code>.
     * @memberof Context.prototype
     * @type {Boolean}
     * @see {@link http://www.khronos.org/registry/webgl/extensions/WEBGL_draw_buffers/|WEBGL_draw_buffers}
     */
    drawBuffers: {
      get: function () {
        return this._drawBuffers || this._webgl2;
      },
    },

    debugShaders: {
      get: function () {
        return this._debugShaders;
      },
    },

    throwOnWebGLError: {
      get: function () {
        return this._throwOnWebGLError;
      },
      set: function (value) {
        this._throwOnWebGLError = value;
        this._gl = wrapGL(
          this._originalGLContext,
          value ? throwOnError : undefined
        );
      },
    },

    /**
     * A 1x1 RGBA texture initialized to [255, 255, 255, 255].  This can
     * be used as a placeholder texture while other textures are downloaded.
     * @memberof Context.prototype
     * @type {Texture}
     */
    defaultTexture: {
      get: function () {
        if (this._defaultTexture === undefined) {
          this._defaultTexture = new Texture({
            context: this,
            source: {
              width: 1,
              height: 1,
              arrayBufferView: new Uint8Array([255, 255, 255, 255]),
            },
            flipY: false,
          });
        }

        return this._defaultTexture;
      },
    },

    /**
     * A cube map, where each face is a 1x1 RGBA texture initialized to
     * [255, 255, 255, 255].  This can be used as a placeholder cube map while
     * other cube maps are downloaded.
     * @memberof Context.prototype
     * @type {CubeMap}
     */
    defaultCubeMap: {
      get: function () {
        if (this._defaultCubeMap === undefined) {
          var face = {
            width: 1,
            height: 1,
            arrayBufferView: new Uint8Array([255, 255, 255, 255]),
          };

          this._defaultCubeMap = new CubeMap({
            context: this,
            source: {
              positiveX: face,
              negativeX: face,
              positiveY: face,
              negativeY: face,
              positiveZ: face,
              negativeZ: face,
            },
            flipY: false,
          });
        }

        return this._defaultCubeMap;
      },
    },

    /**
     * The drawingBufferHeight of the underlying GL context.
     * @memberof Context.prototype
     * @type {Number}
     * @see {@link https://www.khronos.org/registry/webgl/specs/1.0/#DOM-WebGLRenderingContext-drawingBufferHeight|drawingBufferHeight}
     */
    drawingBufferHeight: {
      get: function () {
        return this._gl.drawingBufferHeight;
      },
    },

    /**
     * The drawingBufferWidth of the underlying GL context.
     * @memberof Context.prototype
     * @type {Number}
     * @see {@link https://www.khronos.org/registry/webgl/specs/1.0/#DOM-WebGLRenderingContext-drawingBufferWidth|drawingBufferWidth}
     */
    drawingBufferWidth: {
      get: function () {
        return this._gl.drawingBufferWidth;
      },
    },

    /**
     * Gets an object representing the currently bound framebuffer.  While this instance is not an actual
     * {@link Framebuffer}, it is used to represent the default framebuffer in calls to
     * {@link Texture.fromFramebuffer}.
     * @memberof Context.prototype
     * @type {Object}
     */
    defaultFramebuffer: {
      get: function () {
        return defaultFramebufferMarker;
      },
    },
  });

  /**
   * Validates a framebuffer.
   * Available in debug builds only.
   * @private
   */
  function validateFramebuffer(context) {
    //>>includeStart('debug', pragmas.debug);
    if (context.validateFramebuffer) {
      var gl = context._gl;
      var status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);

      if (status !== gl.FRAMEBUFFER_COMPLETE) {
        var message;

        switch (status) {
          case gl.FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
            message =
              "Framebuffer is not complete.  Incomplete attachment: at least one attachment point with a renderbuffer or texture attached has its attached object no longer in existence or has an attached image with a width or height of zero, or the color attachment point has a non-color-renderable image attached, or the depth attachment point has a non-depth-renderable image attached, or the stencil attachment point has a non-stencil-renderable image attached.  Color-renderable formats include GL_RGBA4, GL_RGB5_A1, and GL_RGB565. GL_DEPTH_COMPONENT16 is the only depth-renderable format. GL_STENCIL_INDEX8 is the only stencil-renderable format.";
            break;
          case gl.FRAMEBUFFER_INCOMPLETE_DIMENSIONS:
            message =
              "Framebuffer is not complete.  Incomplete dimensions: not all attached images have the same width and height.";
            break;
          case gl.FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
            message =
              "Framebuffer is not complete.  Missing attachment: no images are attached to the framebuffer.";
            break;
          case gl.FRAMEBUFFER_UNSUPPORTED:
            message =
              "Framebuffer is not complete.  Unsupported: the combination of internal formats of the attached images violates an implementation-dependent set of restrictions.";
            break;
        }

        throw new DeveloperError(message);
      }
    }
    //>>includeEnd('debug');
  }

  function applyRenderState(context, renderState, passState, clear) {
    var previousRenderState = context._currentRenderState;
    var previousPassState = context._currentPassState;
    context._currentRenderState = renderState;
    context._currentPassState = passState;
    RenderState.partialApply(
      context._gl,
      previousRenderState,
      renderState,
      previousPassState,
      passState,
      clear
    );
  }

  var scratchBackBufferArray;
  // this check must use typeof, not defined, because defined doesn't work with undeclared variables.
  if (typeof WebGLRenderingContext !== "undefined") {
    scratchBackBufferArray = [WebGLConstants$1.BACK];
  }

  function bindFramebuffer(context, framebuffer) {
    if (framebuffer !== context._currentFramebuffer) {
      context._currentFramebuffer = framebuffer;
      var buffers = scratchBackBufferArray;

      if (defined(framebuffer)) {
        framebuffer._bind();
        validateFramebuffer(context);

        // TODO: Need a way for a command to give what draw buffers are active.
        buffers = framebuffer._getActiveColorAttachments();
      } else {
        var gl = context._gl;
        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
      }

      if (context.drawBuffers) {
        context.glDrawBuffers(buffers);
      }
    }
  }

  var defaultClearCommand = new ClearCommand();

  Context.prototype.clear = function (clearCommand, passState) {
    clearCommand = defaultValue(clearCommand, defaultClearCommand);
    passState = defaultValue(passState, this._defaultPassState);

    var gl = this._gl;
    var bitmask = 0;

    var c = clearCommand.color;
    var d = clearCommand.depth;
    var s = clearCommand.stencil;

    if (defined(c)) {
      if (!Color.equals(this._clearColor, c)) {
        Color.clone(c, this._clearColor);
        gl.clearColor(c.red, c.green, c.blue, c.alpha);
      }
      bitmask |= gl.COLOR_BUFFER_BIT;
    }

    if (defined(d)) {
      if (d !== this._clearDepth) {
        this._clearDepth = d;
        gl.clearDepth(d);
      }
      bitmask |= gl.DEPTH_BUFFER_BIT;
    }

    if (defined(s)) {
      if (s !== this._clearStencil) {
        this._clearStencil = s;
        gl.clearStencil(s);
      }
      bitmask |= gl.STENCIL_BUFFER_BIT;
    }

    var rs = defaultValue(clearCommand.renderState, this._defaultRenderState);
    applyRenderState(this, rs, passState, true);

    // The command's framebuffer takes presidence over the pass' framebuffer, e.g., for off-screen rendering.
    var framebuffer = defaultValue(
      clearCommand.framebuffer,
      passState.framebuffer
    );
    bindFramebuffer(this, framebuffer);

    gl.clear(bitmask);
  };

  function beginDraw(
    context,
    framebuffer,
    passState,
    shaderProgram,
    renderState
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (defined(framebuffer) && renderState.depthTest) {
      if (renderState.depthTest.enabled && !framebuffer.hasDepthAttachment) {
        throw new DeveloperError(
          "The depth test can not be enabled (drawCommand.renderState.depthTest.enabled) because the framebuffer (drawCommand.framebuffer) does not have a depth or depth-stencil renderbuffer."
        );
      }
    }
    //>>includeEnd('debug');

    bindFramebuffer(context, framebuffer);
    applyRenderState(context, renderState, passState, false);
    shaderProgram._bind();
    context._maxFrameTextureUnitIndex = Math.max(
      context._maxFrameTextureUnitIndex,
      shaderProgram.maximumTextureUnitIndex
    );
  }

  function continueDraw(context, drawCommand, shaderProgram, uniformMap) {
    var primitiveType = drawCommand._primitiveType;
    var va = drawCommand._vertexArray;
    var offset = drawCommand._offset;
    var count = drawCommand._count;
    var instanceCount = drawCommand.instanceCount;

    //>>includeStart('debug', pragmas.debug);
    if (!PrimitiveType$1.validate(primitiveType)) {
      throw new DeveloperError(
        "drawCommand.primitiveType is required and must be valid."
      );
    }

    Check.defined("drawCommand.vertexArray", va);
    Check.typeOf.number.greaterThanOrEquals("drawCommand.offset", offset, 0);
    if (defined(count)) {
      Check.typeOf.number.greaterThanOrEquals("drawCommand.count", count, 0);
    }
    Check.typeOf.number.greaterThanOrEquals(
      "drawCommand.instanceCount",
      instanceCount,
      0
    );
    if (instanceCount > 0 && !context.instancedArrays) {
      throw new DeveloperError("Instanced arrays extension is not supported");
    }
    //>>includeEnd('debug');

    context._us.model = defaultValue(drawCommand._modelMatrix, Matrix4.IDENTITY);
    shaderProgram._setUniforms(
      uniformMap,
      context._us,
      context.validateShaderProgram
    );

    va._bind();
    var indexBuffer = va.indexBuffer;

    if (defined(indexBuffer)) {
      offset = offset * indexBuffer.bytesPerIndex; // offset in vertices to offset in bytes
      count = defaultValue(count, indexBuffer.numberOfIndices);
      if (instanceCount === 0) {
        context._gl.drawElements(
          primitiveType,
          count,
          indexBuffer.indexDatatype,
          offset
        );
      } else {
        context.glDrawElementsInstanced(
          primitiveType,
          count,
          indexBuffer.indexDatatype,
          offset,
          instanceCount
        );
      }
    } else {
      count = defaultValue(count, va.numberOfVertices);
      if (instanceCount === 0) {
        context._gl.drawArrays(primitiveType, offset, count);
      } else {
        context.glDrawArraysInstanced(
          primitiveType,
          offset,
          count,
          instanceCount
        );
      }
    }

    va._unBind();
  }

  Context.prototype.draw = function (
    drawCommand,
    passState,
    shaderProgram,
    uniformMap
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("drawCommand", drawCommand);
    Check.defined("drawCommand.shaderProgram", drawCommand._shaderProgram);
    //>>includeEnd('debug');

    passState = defaultValue(passState, this._defaultPassState);
    // The command's framebuffer takes presidence over the pass' framebuffer, e.g., for off-screen rendering.
    var framebuffer = defaultValue(
      drawCommand._framebuffer,
      passState.framebuffer
    );
    var renderState = defaultValue(
      drawCommand._renderState,
      this._defaultRenderState
    );
    shaderProgram = defaultValue(shaderProgram, drawCommand._shaderProgram);
    uniformMap = defaultValue(uniformMap, drawCommand._uniformMap);

    beginDraw(this, framebuffer, passState, shaderProgram, renderState);
    continueDraw(this, drawCommand, shaderProgram, uniformMap);
  };

  Context.prototype.endFrame = function () {
    var gl = this._gl;
    gl.useProgram(null);

    this._currentFramebuffer = undefined;
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);

    var buffers = scratchBackBufferArray;
    if (this.drawBuffers) {
      this.glDrawBuffers(buffers);
    }

    var length = this._maxFrameTextureUnitIndex;
    this._maxFrameTextureUnitIndex = 0;

    for (var i = 0; i < length; ++i) {
      gl.activeTexture(gl.TEXTURE0 + i);
      gl.bindTexture(gl.TEXTURE_2D, null);
      gl.bindTexture(gl.TEXTURE_CUBE_MAP, null);
    }
  };

  Context.prototype.readPixels = function (readState) {
    var gl = this._gl;

    readState = defaultValue(readState, defaultValue.EMPTY_OBJECT);
    var x = Math.max(defaultValue(readState.x, 0), 0);
    var y = Math.max(defaultValue(readState.y, 0), 0);
    var width = defaultValue(readState.width, gl.drawingBufferWidth);
    var height = defaultValue(readState.height, gl.drawingBufferHeight);
    var framebuffer = readState.framebuffer;

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThan("readState.width", width, 0);
    Check.typeOf.number.greaterThan("readState.height", height, 0);
    //>>includeEnd('debug');

    var pixelDatatype = PixelDatatype$1.UNSIGNED_BYTE;
    if (defined(framebuffer) && framebuffer.numberOfColorAttachments > 0) {
      pixelDatatype = framebuffer.getColorTexture(0).pixelDatatype;
    }

    var pixels = PixelFormat$1.createTypedArray(
      PixelFormat$1.RGBA,
      pixelDatatype,
      width,
      height
    );

    bindFramebuffer(this, framebuffer);

    gl.readPixels(
      x,
      y,
      width,
      height,
      PixelFormat$1.RGBA,
      PixelDatatype$1.toWebGLConstant(pixelDatatype, this),
      pixels
    );

    return pixels;
  };

  var viewportQuadAttributeLocations = {
    position: 0,
    textureCoordinates: 1,
  };

  Context.prototype.getViewportQuadVertexArray = function () {
    // Per-context cache for viewport quads
    var vertexArray = this.cache.viewportQuad_vertexArray;

    if (!defined(vertexArray)) {
      var geometry = new Geometry({
        attributes: {
          position: new GeometryAttribute({
            componentDatatype: ComponentDatatype$1.FLOAT,
            componentsPerAttribute: 2,
            values: [-1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0],
          }),

          textureCoordinates: new GeometryAttribute({
            componentDatatype: ComponentDatatype$1.FLOAT,
            componentsPerAttribute: 2,
            values: [0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0],
          }),
        },
        // Workaround Internet Explorer 11.0.8 lack of TRIANGLE_FAN
        indices: new Uint16Array([0, 1, 2, 0, 2, 3]),
        primitiveType: PrimitiveType$1.TRIANGLES,
      });

      vertexArray = VertexArray.fromGeometry({
        context: this,
        geometry: geometry,
        attributeLocations: viewportQuadAttributeLocations,
        bufferUsage: BufferUsage$1.STATIC_DRAW,
        interleave: true,
      });

      this.cache.viewportQuad_vertexArray = vertexArray;
    }

    return vertexArray;
  };

  Context.prototype.createViewportQuadCommand = function (
    fragmentShaderSource,
    overrides
  ) {
    overrides = defaultValue(overrides, defaultValue.EMPTY_OBJECT);

    return new DrawCommand({
      vertexArray: this.getViewportQuadVertexArray(),
      primitiveType: PrimitiveType$1.TRIANGLES,
      renderState: overrides.renderState,
      shaderProgram: ShaderProgram.fromCache({
        context: this,
        vertexShaderSource: ViewportQuadVS,
        fragmentShaderSource: fragmentShaderSource,
        attributeLocations: viewportQuadAttributeLocations,
      }),
      uniformMap: overrides.uniformMap,
      owner: overrides.owner,
      framebuffer: overrides.framebuffer,
      pass: overrides.pass,
    });
  };

  /**
   * Gets the object associated with a pick color.
   *
   * @param {Color} pickColor The pick color.
   * @returns {Object} The object associated with the pick color, or undefined if no object is associated with that color.
   *
   * @example
   * var object = context.getObjectByPickColor(pickColor);
   *
   * @see Context#createPickId
   */
  Context.prototype.getObjectByPickColor = function (pickColor) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("pickColor", pickColor);
    //>>includeEnd('debug');

    return this._pickObjects[pickColor.toRgba()];
  };

  function PickId(pickObjects, key, color) {
    this._pickObjects = pickObjects;
    this.key = key;
    this.color = color;
  }

  Object.defineProperties(PickId.prototype, {
    object: {
      get: function () {
        return this._pickObjects[this.key];
      },
      set: function (value) {
        this._pickObjects[this.key] = value;
      },
    },
  });

  PickId.prototype.destroy = function () {
    delete this._pickObjects[this.key];
    return undefined;
  };

  /**
   * Creates a unique ID associated with the input object for use with color-buffer picking.
   * The ID has an RGBA color value unique to this context.  You must call destroy()
   * on the pick ID when destroying the input object.
   *
   * @param {Object} object The object to associate with the pick ID.
   * @returns {Object} A PickId object with a <code>color</code> property.
   *
   * @exception {RuntimeError} Out of unique Pick IDs.
   *
   *
   * @example
   * this._pickId = context.createPickId({
   *   primitive : this,
   *   id : this.id
   * });
   *
   * @see Context#getObjectByPickColor
   */
  Context.prototype.createPickId = function (object) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("object", object);
    //>>includeEnd('debug');

    // the increment and assignment have to be separate statements to
    // actually detect overflow in the Uint32 value
    ++this._nextPickColor[0];
    var key = this._nextPickColor[0];
    if (key === 0) {
      // In case of overflow
      throw new RuntimeError("Out of unique Pick IDs.");
    }

    this._pickObjects[key] = object;
    return new PickId(this._pickObjects, key, Color.fromRgba(key));
  };

  Context.prototype.isDestroyed = function () {
    return false;
  };

  Context.prototype.destroy = function () {
    // Destroy all objects in the cache that have a destroy method.
    var cache = this.cache;
    for (var property in cache) {
      if (cache.hasOwnProperty(property)) {
        var propertyValue = cache[property];
        if (defined(propertyValue.destroy)) {
          propertyValue.destroy();
        }
      }
    }

    this._shaderCache = this._shaderCache.destroy();
    this._textureCache = this._textureCache.destroy();
    this._defaultTexture = this._defaultTexture && this._defaultTexture.destroy();
    this._defaultCubeMap = this._defaultCubeMap && this._defaultCubeMap.destroy();

    return destroyObject(this);
  };

  /**
   * @private
   */
  var RenderbufferFormat = {
    RGBA4: WebGLConstants$1.RGBA4,
    RGB5_A1: WebGLConstants$1.RGB5_A1,
    RGB565: WebGLConstants$1.RGB565,
    DEPTH_COMPONENT16: WebGLConstants$1.DEPTH_COMPONENT16,
    STENCIL_INDEX8: WebGLConstants$1.STENCIL_INDEX8,
    DEPTH_STENCIL: WebGLConstants$1.DEPTH_STENCIL,

    validate: function (renderbufferFormat) {
      return (
        renderbufferFormat === RenderbufferFormat.RGBA4 ||
        renderbufferFormat === RenderbufferFormat.RGB5_A1 ||
        renderbufferFormat === RenderbufferFormat.RGB565 ||
        renderbufferFormat === RenderbufferFormat.DEPTH_COMPONENT16 ||
        renderbufferFormat === RenderbufferFormat.STENCIL_INDEX8 ||
        renderbufferFormat === RenderbufferFormat.DEPTH_STENCIL
      );
    },
  };
  var RenderbufferFormat$1 = Object.freeze(RenderbufferFormat);

  /**
   * @private
   */
  function Renderbuffer(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.context", options.context);
    //>>includeEnd('debug');

    var context = options.context;
    var gl = context._gl;
    var maximumRenderbufferSize = ContextLimits.maximumRenderbufferSize;

    var format = defaultValue(options.format, RenderbufferFormat$1.RGBA4);
    var width = defined(options.width) ? options.width : gl.drawingBufferWidth;
    var height = defined(options.height)
      ? options.height
      : gl.drawingBufferHeight;

    //>>includeStart('debug', pragmas.debug);
    if (!RenderbufferFormat$1.validate(format)) {
      throw new DeveloperError("Invalid format.");
    }

    Check.typeOf.number.greaterThan("width", width, 0);

    if (width > maximumRenderbufferSize) {
      throw new DeveloperError(
        "Width must be less than or equal to the maximum renderbuffer size (" +
          maximumRenderbufferSize +
          ").  Check maximumRenderbufferSize."
      );
    }

    Check.typeOf.number.greaterThan("height", height, 0);

    if (height > maximumRenderbufferSize) {
      throw new DeveloperError(
        "Height must be less than or equal to the maximum renderbuffer size (" +
          maximumRenderbufferSize +
          ").  Check maximumRenderbufferSize."
      );
    }
    //>>includeEnd('debug');

    this._gl = gl;
    this._format = format;
    this._width = width;
    this._height = height;
    this._renderbuffer = this._gl.createRenderbuffer();

    gl.bindRenderbuffer(gl.RENDERBUFFER, this._renderbuffer);
    gl.renderbufferStorage(gl.RENDERBUFFER, format, width, height);
    gl.bindRenderbuffer(gl.RENDERBUFFER, null);
  }

  Object.defineProperties(Renderbuffer.prototype, {
    format: {
      get: function () {
        return this._format;
      },
    },
    width: {
      get: function () {
        return this._width;
      },
    },
    height: {
      get: function () {
        return this._height;
      },
    },
  });

  Renderbuffer.prototype._getRenderbuffer = function () {
    return this._renderbuffer;
  };

  Renderbuffer.prototype.isDestroyed = function () {
    return false;
  };

  Renderbuffer.prototype.destroy = function () {
    this._gl.deleteRenderbuffer(this._renderbuffer);
    return destroyObject(this);
  };

  /**
   * Asynchronously loads six images and creates a cube map.  Returns a promise that
   * will resolve to a {@link CubeMap} once loaded, or reject if any image fails to load.
   *
   * @function loadCubeMap
   *
   * @param {Context} context The context to use to create the cube map.
   * @param {Object} urls The source URL of each image.  See the example below.
   * @returns {Promise.<CubeMap>} a promise that will resolve to the requested {@link CubeMap} when loaded.
   *
   * @exception {DeveloperError} context is required.
   * @exception {DeveloperError} urls is required and must have positiveX, negativeX, positiveY, negativeY, positiveZ, and negativeZ properties.
   *
   *
   * @example
   * Cesium.loadCubeMap(context, {
   *     positiveX : 'skybox_px.png',
   *     negativeX : 'skybox_nx.png',
   *     positiveY : 'skybox_py.png',
   *     negativeY : 'skybox_ny.png',
   *     positiveZ : 'skybox_pz.png',
   *     negativeZ : 'skybox_nz.png'
   * }).then(function(cubeMap) {
   *     // use the cubemap
   * }).otherwise(function(error) {
   *     // an error occurred
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   * @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
   *
   * @private
   */
  function loadCubeMap(context, urls) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("context", context);
    if (
      !defined(urls) ||
      !defined(urls.positiveX) ||
      !defined(urls.negativeX) ||
      !defined(urls.positiveY) ||
      !defined(urls.negativeY) ||
      !defined(urls.positiveZ) ||
      !defined(urls.negativeZ)
    ) {
      throw new DeveloperError(
        "urls is required and must have positiveX, negativeX, positiveY, negativeY, positiveZ, and negativeZ properties."
      );
    }
    //>>includeEnd('debug');

    // PERFORMANCE_IDEA: Given the size of some cube maps, we should consider tiling them, which
    // would prevent hiccups when uploading, for example, six 4096x4096 textures to the GPU.
    //
    // Also, it is perhaps acceptable to use the context here in the callbacks, but
    // ideally, we would do it in the primitive's update function.
    var flipOptions = {
      flipY: true,
      preferImageBitmap: true,
    };

    var facePromises = [
      Resource.createIfNeeded(urls.positiveX).fetchImage(flipOptions),
      Resource.createIfNeeded(urls.negativeX).fetchImage(flipOptions),
      Resource.createIfNeeded(urls.positiveY).fetchImage(flipOptions),
      Resource.createIfNeeded(urls.negativeY).fetchImage(flipOptions),
      Resource.createIfNeeded(urls.positiveZ).fetchImage(flipOptions),
      Resource.createIfNeeded(urls.negativeZ).fetchImage(flipOptions),
    ];

    return when.all(facePromises, function (images) {
      return new CubeMap({
        context: context,
        source: {
          positiveX: images[0],
          negativeX: images[1],
          positiveY: images[2],
          negativeY: images[3],
          positiveZ: images[4],
          negativeZ: images[5],
        },
      });
    });
  }

  /**
   * A policy for discarding tile images that match a known image containing a
   * "missing" image.
   *
   * @alias DiscardMissingTileImagePolicy
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Resource|String} options.missingImageUrl The URL of the known missing image.
   * @param {Cartesian2[]} options.pixelsToCheck An array of {@link Cartesian2} pixel positions to
   *        compare against the missing image.
   * @param {Boolean} [options.disableCheckIfAllPixelsAreTransparent=false] If true, the discard check will be disabled
   *                  if all of the pixelsToCheck in the missingImageUrl have an alpha value of 0.  If false, the
   *                  discard check will proceed no matter the values of the pixelsToCheck.
   */
  function DiscardMissingTileImagePolicy(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.missingImageUrl)) {
      throw new DeveloperError("options.missingImageUrl is required.");
    }

    if (!defined(options.pixelsToCheck)) {
      throw new DeveloperError("options.pixelsToCheck is required.");
    }
    //>>includeEnd('debug');

    this._pixelsToCheck = options.pixelsToCheck;
    this._missingImagePixels = undefined;
    this._missingImageByteLength = undefined;
    this._isReady = false;

    var resource = Resource.createIfNeeded(options.missingImageUrl);

    var that = this;

    function success(image) {
      if (defined(image.blob)) {
        that._missingImageByteLength = image.blob.size;
      }

      var pixels = getImagePixels(image);

      if (options.disableCheckIfAllPixelsAreTransparent) {
        var allAreTransparent = true;
        var width = image.width;

        var pixelsToCheck = options.pixelsToCheck;
        for (
          var i = 0, len = pixelsToCheck.length;
          allAreTransparent && i < len;
          ++i
        ) {
          var pos = pixelsToCheck[i];
          var index = pos.x * 4 + pos.y * width;
          var alpha = pixels[index + 3];

          if (alpha > 0) {
            allAreTransparent = false;
          }
        }

        if (allAreTransparent) {
          pixels = undefined;
        }
      }

      that._missingImagePixels = pixels;
      that._isReady = true;
    }

    function failure() {
      // Failed to download "missing" image, so assume that any truly missing tiles
      // will also fail to download and disable the discard check.
      that._missingImagePixels = undefined;
      that._isReady = true;
    }

    resource
      .fetchImage({
        preferBlob: true,
        preferImageBitmap: true,
        flipY: true,
      })
      .then(success)
      .otherwise(failure);
  }

  /**
   * Determines if the discard policy is ready to process images.
   * @returns {Boolean} True if the discard policy is ready to process images; otherwise, false.
   */
  DiscardMissingTileImagePolicy.prototype.isReady = function () {
    return this._isReady;
  };

  /**
   * Given a tile image, decide whether to discard that image.
   *
   * @param {HTMLImageElement} image An image to test.
   * @returns {Boolean} True if the image should be discarded; otherwise, false.
   *
   * @exception {DeveloperError} <code>shouldDiscardImage</code> must not be called before the discard policy is ready.
   */
  DiscardMissingTileImagePolicy.prototype.shouldDiscardImage = function (image) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._isReady) {
      throw new DeveloperError(
        "shouldDiscardImage must not be called before the discard policy is ready."
      );
    }
    //>>includeEnd('debug');

    var pixelsToCheck = this._pixelsToCheck;
    var missingImagePixels = this._missingImagePixels;

    // If missingImagePixels is undefined, it indicates that the discard check has been disabled.
    if (!defined(missingImagePixels)) {
      return false;
    }

    if (defined(image.blob) && image.blob.size !== this._missingImageByteLength) {
      return false;
    }

    var pixels = getImagePixels(image);
    var width = image.width;

    for (var i = 0, len = pixelsToCheck.length; i < len; ++i) {
      var pos = pixelsToCheck[i];
      var index = pos.x * 4 + pos.y * width;
      for (var offset = 0; offset < 4; ++offset) {
        var pixel = index + offset;
        if (pixels[pixel] !== missingImagePixels[pixel]) {
          return false;
        }
      }
    }
    return true;
  };

  /**
   * Describes a rasterized feature, such as a point, polygon, polyline, etc., in an imagery layer.
   *
   * @alias ImageryLayerFeatureInfo
   * @constructor
   */
  function ImageryLayerFeatureInfo() {
    /**
     * Gets or sets the name of the feature.
     * @type {String|undefined}
     */
    this.name = undefined;

    /**
     * Gets or sets an HTML description of the feature.  The HTML is not trusted and should
     * be sanitized before display to the user.
     * @type {String|undefined}
     */
    this.description = undefined;

    /**
     * Gets or sets the position of the feature, or undefined if the position is not known.
     *
     * @type {Cartographic|undefined}
     */
    this.position = undefined;

    /**
     * Gets or sets the raw data describing the feature.  The raw data may be in any
     * number of formats, such as GeoJSON, KML, etc.
     * @type {Object|undefined}
     */
    this.data = undefined;

    /**
     * Gets or sets the image layer of the feature.
     * @type {Object|undefined}
     */
    this.imageryLayer = undefined;
  }

  /**
   * Configures the name of this feature by selecting an appropriate property.  The name will be obtained from
   * one of the following sources, in this order: 1) the property with the name 'name', 2) the property with the name 'title',
   * 3) the first property containing the word 'name', 4) the first property containing the word 'title'.  If
   * the name cannot be obtained from any of these sources, the existing name will be left unchanged.
   *
   * @param {Object} properties An object literal containing the properties of the feature.
   */
  ImageryLayerFeatureInfo.prototype.configureNameFromProperties = function (
    properties
  ) {
    var namePropertyPrecedence = 10;
    var nameProperty;

    for (var key in properties) {
      if (properties.hasOwnProperty(key) && properties[key]) {
        var lowerKey = key.toLowerCase();

        if (namePropertyPrecedence > 1 && lowerKey === "name") {
          namePropertyPrecedence = 1;
          nameProperty = key;
        } else if (namePropertyPrecedence > 2 && lowerKey === "title") {
          namePropertyPrecedence = 2;
          nameProperty = key;
        } else if (namePropertyPrecedence > 3 && /name/i.test(key)) {
          namePropertyPrecedence = 3;
          nameProperty = key;
        } else if (namePropertyPrecedence > 4 && /title/i.test(key)) {
          namePropertyPrecedence = 4;
          nameProperty = key;
        }
      }
    }

    if (defined(nameProperty)) {
      this.name = properties[nameProperty];
    }
  };

  /**
   * Configures the description of this feature by creating an HTML table of properties and their values.
   *
   * @param {Object} properties An object literal containing the properties of the feature.
   */
  ImageryLayerFeatureInfo.prototype.configureDescriptionFromProperties = function (
    properties
  ) {
    function describe(properties) {
      var html = '<table class="cesium-infoBox-defaultTable">';
      for (var key in properties) {
        if (properties.hasOwnProperty(key)) {
          var value = properties[key];
          if (defined(value)) {
            if (typeof value === "object") {
              html +=
                "<tr><td>" + key + "</td><td>" + describe(value) + "</td></tr>";
            } else {
              html += "<tr><td>" + key + "</td><td>" + value + "</td></tr>";
            }
          }
        }
      }
      html += "</table>";

      return html;
    }

    this.description = describe(properties);
  };

  /**
   * Provides imagery to be displayed on the surface of an ellipsoid.  This type describes an
   * interface and is not intended to be instantiated directly.
   *
   * @alias ImageryProvider
   * @constructor
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see OpenStreetMapImageryProvider
   * @see TileMapServiceImageryProvider
   * @see GoogleEarthEnterpriseImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see GridImageryProvider
   * @see IonImageryProvider
   * @see MapboxImageryProvider
   * @see MapboxStyleImageryProvider
   * @see SingleTileImageryProvider
   * @see TileCoordinatesImageryProvider
   * @see UrlTemplateImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Imagery%20Layers.html|Cesium Sandcastle Imagery Layers Demo}
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Imagery%20Layers%20Manipulation.html|Cesium Sandcastle Imagery Manipulation Demo}
   */
  function ImageryProvider() {
    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    DeveloperError.throwInstantiationError();
  }

  Object.defineProperties(ImageryProvider.prototype, {
    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof ImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof ImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by the instance.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the width of each tile, in pixels.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link ImageryProvider#ready} returns true. Generally,
     * a minimum level should only be used when the rectangle of the imagery is small
     * enough that the number of tiles at the minimum level is small.  An imagery
     * provider with more than a few tiles at the minimum level will lead to
     * rendering problems.
     * @memberof ImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the tiling scheme used by the provider.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error..  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof ImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery. This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof ImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof ImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof ImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  ImageryProvider.prototype.getTileCredits = function (x, y, level) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link ImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  ImageryProvider.prototype.requestImage = function (x, y, level, request) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Asynchronously determines what features, if any, are located at a given longitude and latitude within
   * a tile.  This function should not be called before {@link ImageryProvider#ready} returns true.
   * This function is optional, so it may not exist on all ImageryProviders.
   *
   * @function
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   *
   * @exception {DeveloperError} <code>pickFeatures</code> must not be called before the imagery provider is ready.
   */
  ImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    DeveloperError.throwInstantiationError();
  };

  var ktxRegex$2 = /\.ktx$/i;
  var crnRegex$2 = /\.crn$/i;

  /**
   * Loads an image from a given URL.  If the server referenced by the URL already has
   * too many requests pending, this function will instead return undefined, indicating
   * that the request should be retried later.
   *
   * @param {ImageryProvider} imageryProvider The imagery provider for the URL.
   * @param {Resource|String} url The URL of the image.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   */
  ImageryProvider.loadImage = function (imageryProvider, url) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("url", url);
    //>>includeEnd('debug');

    var resource = Resource.createIfNeeded(url);

    if (ktxRegex$2.test(resource.url)) {
      return loadKTX(resource);
    } else if (crnRegex$2.test(resource.url)) {
      return loadCRN(resource);
    } else if (
      defined(imageryProvider) &&
      defined(imageryProvider.tileDiscardPolicy)
    ) {
      return resource.fetchImage({
        preferBlob: true,
        preferImageBitmap: true,
        flipY: true,
      });
    }

    return resource.fetchImage({
      preferImageBitmap: true,
      flipY: true,
    });
  };

  /**
   * @typedef {Object} ArcGisMapServerImageryProvider.ConstructorOptions
   *
   * Initialization options for the ArcGisMapServerImageryProvider constructor
   *
   * @property {Resource|String} url The URL of the ArcGIS MapServer service.
   * @property {String} [token] The ArcGIS token used to authenticate with the ArcGIS MapServer service.
   * @property {TileDiscardPolicy} [tileDiscardPolicy] The policy that determines if a tile
   *        is invalid and should be discarded.  If this value is not specified, a default
   *        {@link DiscardMissingTileImagePolicy} is used for tiled map servers, and a
   *        {@link NeverTileDiscardPolicy} is used for non-tiled map servers.  In the former case,
   *        we request tile 0,0 at the maximum tile level and check pixels (0,0), (200,20), (20,200),
   *        (80,110), and (160, 130).  If all of these pixels are transparent, the discard check is
   *        disabled and no tiles are discarded.  If any of them have a non-transparent color, any
   *        tile that has the same values in these pixel locations is discarded.  The end result of
   *        these defaults should be correct tile discarding for a standard ArcGIS Server.  To ensure
   *        that no tiles are discarded, construct and pass a {@link NeverTileDiscardPolicy} for this
   *        parameter.
   * @property {Boolean} [usePreCachedTilesIfAvailable=true] If true, the server's pre-cached
   *        tiles are used if they are available.  If false, any pre-cached tiles are ignored and the
   *        'export' service is used.
   * @property {String} [layers] A comma-separated list of the layers to show, or undefined if all layers should be shown.
   * @property {Boolean} [enablePickFeatures=true] If true, {@link ArcGisMapServerImageryProvider#pickFeatures} will invoke
   *        the Identify service on the MapServer and return the features included in the response.  If false,
   *        {@link ArcGisMapServerImageryProvider#pickFeatures} will immediately return undefined (indicating no pickable features)
   *        without communicating with the server.  Set this property to false if you don't want this provider's features to
   *        be pickable. Can be overridden by setting the {@link ArcGisMapServerImageryProvider#enablePickFeatures} property on the object.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle of the layer.  This parameter is ignored when accessing
   *                    a tiled layer.
   * @property {TilingScheme} [tilingScheme=new GeographicTilingScheme()] The tiling scheme to use to divide the world into tiles.
   *                       This parameter is ignored when accessing a tiled server.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If the tilingScheme is specified and used,
   *                    this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   *                    parameter is specified, the WGS84 ellipsoid is used.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.  This parameter is ignored when accessing a tiled server.
   * @property {Number} [tileWidth=256] The width of each tile in pixels.  This parameter is ignored when accessing a tiled server.
   * @property {Number} [tileHeight=256] The height of each tile in pixels.  This parameter is ignored when accessing a tiled server.
   * @property {Number} [maximumLevel] The maximum tile level to request, or undefined if there is no maximum.  This parameter is ignored when accessing
   *                                        a tiled server.
   */

  /**
   * Provides tiled imagery hosted by an ArcGIS MapServer.  By default, the server's pre-cached tiles are
   * used, if available.
   *
   * @alias ArcGisMapServerImageryProvider
   * @constructor
   *
   * @param {ArcGisMapServerImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   *
   * @example
   * var esri = new Cesium.ArcGisMapServerImageryProvider({
   *     url : 'https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer'
   * });
   *
   * @see {@link https://developers.arcgis.com/rest/|ArcGIS Server REST API}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  function ArcGisMapServerImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var resource = Resource.createIfNeeded(options.url);
    resource.appendForwardSlash();

    if (defined(options.token)) {
      resource.setQueryParameters({
        token: options.token,
      });
    }

    this._resource = resource;
    this._tileDiscardPolicy = options.tileDiscardPolicy;

    this._tileWidth = defaultValue(options.tileWidth, 256);
    this._tileHeight = defaultValue(options.tileHeight, 256);
    this._maximumLevel = options.maximumLevel;
    this._tilingScheme = defaultValue(
      options.tilingScheme,
      new GeographicTilingScheme({ ellipsoid: options.ellipsoid })
    );
    this._useTiles = defaultValue(options.usePreCachedTilesIfAvailable, true);
    this._rectangle = defaultValue(
      options.rectangle,
      this._tilingScheme.rectangle
    );
    this._layers = options.layers;

    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    /**
     * Gets or sets a value indicating whether feature picking is enabled.  If true, {@link ArcGisMapServerImageryProvider#pickFeatures} will
     * invoke the "identify" operation on the ArcGIS server and return the features included in the response.  If false,
     * {@link ArcGisMapServerImageryProvider#pickFeatures} will immediately return undefined (indicating no pickable features)
     * without communicating with the server.
     * @type {Boolean}
     * @default true
     */
    this.enablePickFeatures = defaultValue(options.enablePickFeatures, true);

    this._errorEvent = new Event();

    this._ready = false;
    this._readyPromise = when.defer();

    // Grab the details of this MapServer.
    var that = this;
    var metadataError;

    function metadataSuccess(data) {
      var tileInfo = data.tileInfo;
      if (!defined(tileInfo)) {
        that._useTiles = false;
      } else {
        that._tileWidth = tileInfo.rows;
        that._tileHeight = tileInfo.cols;

        if (
          tileInfo.spatialReference.wkid === 102100 ||
          tileInfo.spatialReference.wkid === 102113
        ) {
          that._tilingScheme = new WebMercatorTilingScheme({
            ellipsoid: options.ellipsoid,
          });
        } else if (data.tileInfo.spatialReference.wkid === 4326) {
          that._tilingScheme = new GeographicTilingScheme({
            ellipsoid: options.ellipsoid,
          });
        } else {
          var message =
            "Tile spatial reference WKID " +
            data.tileInfo.spatialReference.wkid +
            " is not supported.";
          metadataError = TileProviderError.handleError(
            metadataError,
            that,
            that._errorEvent,
            message,
            undefined,
            undefined,
            undefined,
            requestMetadata
          );
          return;
        }
        that._maximumLevel = data.tileInfo.lods.length - 1;

        if (defined(data.fullExtent)) {
          if (
            defined(data.fullExtent.spatialReference) &&
            defined(data.fullExtent.spatialReference.wkid)
          ) {
            if (
              data.fullExtent.spatialReference.wkid === 102100 ||
              data.fullExtent.spatialReference.wkid === 102113
            ) {
              var projection = new WebMercatorProjection();
              var extent = data.fullExtent;
              var sw = projection.unproject(
                new Cartesian3(
                  Math.max(
                    extent.xmin,
                    -that._tilingScheme.ellipsoid.maximumRadius * Math.PI
                  ),
                  Math.max(
                    extent.ymin,
                    -that._tilingScheme.ellipsoid.maximumRadius * Math.PI
                  ),
                  0.0
                )
              );
              var ne = projection.unproject(
                new Cartesian3(
                  Math.min(
                    extent.xmax,
                    that._tilingScheme.ellipsoid.maximumRadius * Math.PI
                  ),
                  Math.min(
                    extent.ymax,
                    that._tilingScheme.ellipsoid.maximumRadius * Math.PI
                  ),
                  0.0
                )
              );
              that._rectangle = new Rectangle(
                sw.longitude,
                sw.latitude,
                ne.longitude,
                ne.latitude
              );
            } else if (data.fullExtent.spatialReference.wkid === 4326) {
              that._rectangle = Rectangle.fromDegrees(
                data.fullExtent.xmin,
                data.fullExtent.ymin,
                data.fullExtent.xmax,
                data.fullExtent.ymax
              );
            } else {
              var extentMessage =
                "fullExtent.spatialReference WKID " +
                data.fullExtent.spatialReference.wkid +
                " is not supported.";
              metadataError = TileProviderError.handleError(
                metadataError,
                that,
                that._errorEvent,
                extentMessage,
                undefined,
                undefined,
                undefined,
                requestMetadata
              );
              return;
            }
          }
        } else {
          that._rectangle = that._tilingScheme.rectangle;
        }

        // Install the default tile discard policy if none has been supplied.
        if (!defined(that._tileDiscardPolicy)) {
          that._tileDiscardPolicy = new DiscardMissingTileImagePolicy({
            missingImageUrl: buildImageResource(that, 0, 0, that._maximumLevel)
              .url,
            pixelsToCheck: [
              new Cartesian2(0, 0),
              new Cartesian2(200, 20),
              new Cartesian2(20, 200),
              new Cartesian2(80, 110),
              new Cartesian2(160, 130),
            ],
            disableCheckIfAllPixelsAreTransparent: true,
          });
        }

        that._useTiles = true;
      }

      if (defined(data.copyrightText) && data.copyrightText.length > 0) {
        that._credit = new Credit(data.copyrightText);
      }

      that._ready = true;
      that._readyPromise.resolve(true);
      TileProviderError.handleSuccess(metadataError);
    }

    function metadataFailure(e) {
      var message =
        "An error occurred while accessing " + that._resource.url + ".";
      metadataError = TileProviderError.handleError(
        metadataError,
        that,
        that._errorEvent,
        message,
        undefined,
        undefined,
        undefined,
        requestMetadata
      );
      that._readyPromise.reject(new RuntimeError(message));
    }

    function requestMetadata() {
      var resource = that._resource.getDerivedResource({
        queryParameters: {
          f: "json",
        },
      });
      var metadata = resource.fetchJsonp();
      when(metadata, metadataSuccess, metadataFailure);
    }

    if (this._useTiles) {
      requestMetadata();
    } else {
      this._ready = true;
      this._readyPromise.resolve(true);
    }
  }

  function buildImageResource(imageryProvider, x, y, level, request) {
    var resource;
    if (imageryProvider._useTiles) {
      resource = imageryProvider._resource.getDerivedResource({
        url: "tile/" + level + "/" + y + "/" + x,
        request: request,
      });
    } else {
      var nativeRectangle = imageryProvider._tilingScheme.tileXYToNativeRectangle(
        x,
        y,
        level
      );
      var bbox =
        nativeRectangle.west +
        "," +
        nativeRectangle.south +
        "," +
        nativeRectangle.east +
        "," +
        nativeRectangle.north;

      var query = {
        bbox: bbox,
        size: imageryProvider._tileWidth + "," + imageryProvider._tileHeight,
        format: "png",
        transparent: true,
        f: "image",
      };

      if (
        imageryProvider._tilingScheme.projection instanceof GeographicProjection
      ) {
        query.bboxSR = 4326;
        query.imageSR = 4326;
      } else {
        query.bboxSR = 3857;
        query.imageSR = 3857;
      }
      if (imageryProvider.layers) {
        query.layers = "show:" + imageryProvider.layers;
      }

      resource = imageryProvider._resource.getDerivedResource({
        url: "export",
        request: request,
        queryParameters: query,
      });
    }

    return resource;
  }

  Object.defineProperties(ArcGisMapServerImageryProvider.prototype, {
    /**
     * Gets the URL of the ArcGIS MapServer.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource._url;
      },
    },

    /**
     * Gets the ArcGIS token used to authenticate with the ArcGis MapServer service.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    token: {
      get: function () {
        return this._resource.queryParameters.token;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return 0;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "rectangle must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
     * @memberof ArcGisMapServerImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether this imagery provider is using pre-cached tiles from the
     * ArcGIS MapServer.  If the imagery provider is not yet ready ({@link ArcGisMapServerImageryProvider#ready}), this function
     * will return the value of `options.usePreCachedTilesIfAvailable`, even if the MapServer does
     * not have pre-cached tiles.
     * @memberof ArcGisMapServerImageryProvider.prototype
     *
     * @type {Boolean}
     * @readonly
     * @default true
     */
    usingPrecachedTiles: {
      get: function () {
        return this._useTiles;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof ArcGisMapServerImageryProvider.prototype
     *
     * @type {Boolean}
     * @readonly
     * @default true
     */
    hasAlphaChannel: {
      get: function () {
        return true;
      },
    },

    /**
     * Gets the comma-separated list of layer IDs to show.
     * @memberof ArcGisMapServerImageryProvider.prototype
     *
     * @type {String}
     */
    layers: {
      get: function () {
        return this._layers;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  ArcGisMapServerImageryProvider.prototype.getTileCredits = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  ArcGisMapServerImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    return ImageryProvider.loadImage(
      this,
      buildImageResource(this, x, y, level, request)
    );
  };

  /**
      /**
       * Asynchronously determines what features, if any, are located at a given longitude and latitude within
       * a tile.  This function should not be called before {@link ImageryProvider#ready} returns true.
       *
       * @param {Number} x The tile X coordinate.
       * @param {Number} y The tile Y coordinate.
       * @param {Number} level The tile level.
       * @param {Number} longitude The longitude at which to pick features.
       * @param {Number} latitude  The latitude at which to pick features.
       * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
       *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
       *                   instances.  The array may be empty if no features are found at the given location.
       *
       * @exception {DeveloperError} <code>pickFeatures</code> must not be called before the imagery provider is ready.
       */
  ArcGisMapServerImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "pickFeatures must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    if (!this.enablePickFeatures) {
      return undefined;
    }

    var rectangle = this._tilingScheme.tileXYToNativeRectangle(x, y, level);

    var horizontal;
    var vertical;
    var sr;
    if (this._tilingScheme.projection instanceof GeographicProjection) {
      horizontal = CesiumMath.toDegrees(longitude);
      vertical = CesiumMath.toDegrees(latitude);
      sr = "4326";
    } else {
      var projected = this._tilingScheme.projection.project(
        new Cartographic(longitude, latitude, 0.0)
      );
      horizontal = projected.x;
      vertical = projected.y;
      sr = "3857";
    }

    var layers = "visible";
    if (defined(this._layers)) {
      layers += ":" + this._layers;
    }

    var query = {
      f: "json",
      tolerance: 2,
      geometryType: "esriGeometryPoint",
      geometry: horizontal + "," + vertical,
      mapExtent:
        rectangle.west +
        "," +
        rectangle.south +
        "," +
        rectangle.east +
        "," +
        rectangle.north,
      imageDisplay: this._tileWidth + "," + this._tileHeight + ",96",
      sr: sr,
      layers: layers,
    };

    var resource = this._resource.getDerivedResource({
      url: "identify",
      queryParameters: query,
    });

    return resource.fetchJson().then(function (json) {
      var result = [];

      var features = json.results;
      if (!defined(features)) {
        return result;
      }

      for (var i = 0; i < features.length; ++i) {
        var feature = features[i];

        var featureInfo = new ImageryLayerFeatureInfo();
        featureInfo.data = feature;
        featureInfo.name = feature.value;
        featureInfo.properties = feature.attributes;
        featureInfo.configureDescriptionFromProperties(feature.attributes);

        // If this is a point feature, use the coordinates of the point.
        if (feature.geometryType === "esriGeometryPoint" && feature.geometry) {
          var wkid =
            feature.geometry.spatialReference &&
            feature.geometry.spatialReference.wkid
              ? feature.geometry.spatialReference.wkid
              : 4326;
          if (wkid === 4326 || wkid === 4283) {
            featureInfo.position = Cartographic.fromDegrees(
              feature.geometry.x,
              feature.geometry.y,
              feature.geometry.z
            );
          } else if (wkid === 102100 || wkid === 900913 || wkid === 3857) {
            var projection = new WebMercatorProjection();
            featureInfo.position = projection.unproject(
              new Cartesian3(
                feature.geometry.x,
                feature.geometry.y,
                feature.geometry.z
              )
            );
          }
        }

        result.push(featureInfo);
      }

      return result;
    });
  };

  /**
   * A post process stage that will get the luminance value at each pixel and
   * uses parallel reduction to compute the average luminance in a 1x1 texture.
   * This texture can be used as input for tone mapping.
   *
   * @constructor
   * @private
   */
  function AutoExposure() {
    this._uniformMap = undefined;
    this._command = undefined;

    this._colorTexture = undefined;
    this._depthTexture = undefined;

    this._ready = false;

    this._name = "czm_autoexposure";

    this._logDepthChanged = undefined;
    this._useLogDepth = undefined;

    this._framebuffers = undefined;
    this._previousLuminance = undefined;

    this._commands = undefined;
    this._clearCommand = undefined;

    this._minMaxLuminance = new Cartesian2();

    /**
     * Whether or not to execute this post-process stage when ready.
     *
     * @type {Boolean}
     */
    this.enabled = true;
    this._enabled = true;

    /**
     * The minimum value used to clamp the luminance.
     *
     * @type {Number}
     * @default 0.1
     */
    this.minimumLuminance = 0.1;

    /**
     * The maximum value used to clamp the luminance.
     *
     * @type {Number}
     * @default 10.0
     */
    this.maximumLuminance = 10.0;
  }

  Object.defineProperties(AutoExposure.prototype, {
    /**
     * Determines if this post-process stage is ready to be executed. A stage is only executed when both <code>ready</code>
     * and {@link AutoExposure#enabled} are <code>true</code>. A stage will not be ready while it is waiting on textures
     * to load.
     *
     * @memberof AutoExposure.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },
    /**
     * The unique name of this post-process stage for reference by other stages.
     *
     * @memberof AutoExposure.prototype
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },

    /**
     * A reference to the texture written to when executing this post process stage.
     *
     * @memberof AutoExposure.prototype
     * @type {Texture}
     * @readonly
     * @private
     */
    outputTexture: {
      get: function () {
        var framebuffers = this._framebuffers;
        if (!defined(framebuffers)) {
          return undefined;
        }
        return framebuffers[framebuffers.length - 1].getColorTexture(0);
      },
    },
  });

  function destroyFramebuffers(autoexposure) {
    var framebuffers = autoexposure._framebuffers;
    if (!defined(framebuffers)) {
      return;
    }

    var length = framebuffers.length;
    for (var i = 0; i < length; ++i) {
      framebuffers[i].destroy();
    }
    autoexposure._framebuffers = undefined;

    autoexposure._previousLuminance.destroy();
    autoexposure._previousLuminance = undefined;
  }

  function createFramebuffers(autoexposure, context) {
    destroyFramebuffers(autoexposure);

    var width = autoexposure._width;
    var height = autoexposure._height;

    var pixelFormat = PixelFormat$1.RGBA;
    var pixelDatatype = context.halfFloatingPointTexture
      ? PixelDatatype$1.HALF_FLOAT
      : PixelDatatype$1.FLOAT;

    var length = Math.ceil(Math.log(Math.max(width, height)) / Math.log(3.0));
    var framebuffers = new Array(length);
    for (var i = 0; i < length; ++i) {
      width = Math.max(Math.ceil(width / 3.0), 1.0);
      height = Math.max(Math.ceil(height / 3.0), 1.0);
      framebuffers[i] = new Framebuffer({
        context: context,
        colorTextures: [
          new Texture({
            context: context,
            width: width,
            height: height,
            pixelFormat: pixelFormat,
            pixelDatatype: pixelDatatype,
            sampler: Sampler.NEAREST,
          }),
        ],
      });
    }

    var lastTexture = framebuffers[length - 1].getColorTexture(0);
    autoexposure._previousLuminance = new Framebuffer({
      context: context,
      colorTextures: [
        new Texture({
          context: context,
          width: lastTexture.width,
          height: lastTexture.height,
          pixelFormat: pixelFormat,
          pixelDatatype: pixelDatatype,
          sampler: Sampler.NEAREST,
        }),
      ],
    });

    autoexposure._framebuffers = framebuffers;
  }

  function destroyCommands(autoexposure) {
    var commands = autoexposure._commands;
    if (!defined(commands)) {
      return;
    }

    var length = commands.length;
    for (var i = 0; i < length; ++i) {
      commands[i].shaderProgram.destroy();
    }
    autoexposure._commands = undefined;
  }

  function createUniformMap$4(autoexposure, index) {
    var uniforms;
    if (index === 0) {
      uniforms = {
        colorTexture: function () {
          return autoexposure._colorTexture;
        },
        colorTextureDimensions: function () {
          return autoexposure._colorTexture.dimensions;
        },
      };
    } else {
      var texture = autoexposure._framebuffers[index - 1].getColorTexture(0);
      uniforms = {
        colorTexture: function () {
          return texture;
        },
        colorTextureDimensions: function () {
          return texture.dimensions;
        },
      };
    }

    uniforms.minMaxLuminance = function () {
      return autoexposure._minMaxLuminance;
    };
    uniforms.previousLuminance = function () {
      return autoexposure._previousLuminance.getColorTexture(0);
    };

    return uniforms;
  }

  function getShaderSource(index, length) {
    var source =
      "uniform sampler2D colorTexture; \n" +
      "varying vec2 v_textureCoordinates; \n" +
      "float sampleTexture(vec2 offset) { \n";

    if (index === 0) {
      source +=
        "    vec4 color = texture2D(colorTexture, v_textureCoordinates + offset); \n" +
        "    return czm_luminance(color.rgb); \n";
    } else {
      source +=
        "    return texture2D(colorTexture, v_textureCoordinates + offset).r; \n";
    }

    source += "}\n\n";

    source +=
      "uniform vec2 colorTextureDimensions; \n" +
      "uniform vec2 minMaxLuminance; \n" +
      "uniform sampler2D previousLuminance; \n" +
      "void main() { \n" +
      "    float color = 0.0; \n" +
      "    float xStep = 1.0 / colorTextureDimensions.x; \n" +
      "    float yStep = 1.0 / colorTextureDimensions.y; \n" +
      "    int count = 0; \n" +
      "    for (int i = 0; i < 3; ++i) { \n" +
      "        for (int j = 0; j < 3; ++j) { \n" +
      "            vec2 offset; \n" +
      "            offset.x = -xStep + float(i) * xStep; \n" +
      "            offset.y = -yStep + float(j) * yStep; \n" +
      "            if (offset.x < 0.0 || offset.x > 1.0 || offset.y < 0.0 || offset.y > 1.0) { \n" +
      "                continue; \n" +
      "            } \n" +
      "            color += sampleTexture(offset); \n" +
      "            ++count; \n" +
      "        } \n" +
      "    } \n" +
      "    if (count > 0) { \n" +
      "        color /= float(count); \n" +
      "    } \n";

    if (index === length - 1) {
      source +=
        "    float previous = texture2D(previousLuminance, vec2(0.5)).r; \n" +
        "    color = clamp(color, minMaxLuminance.x, minMaxLuminance.y); \n" +
        "    color = previous + (color - previous) / (60.0 * 1.5); \n" +
        "    color = clamp(color, minMaxLuminance.x, minMaxLuminance.y); \n";
    }

    source += "    gl_FragColor = vec4(color); \n" + "} \n";
    return source;
  }

  function createCommands$5(autoexposure, context) {
    destroyCommands(autoexposure);
    var framebuffers = autoexposure._framebuffers;
    var length = framebuffers.length;

    var commands = new Array(length);

    for (var i = 0; i < length; ++i) {
      commands[i] = context.createViewportQuadCommand(
        getShaderSource(i, length),
        {
          framebuffer: framebuffers[i],
          uniformMap: createUniformMap$4(autoexposure, i),
        }
      );
    }
    autoexposure._commands = commands;
  }

  /**
   * A function that will be called before execute. Used to clear any textures attached to framebuffers.
   * @param {Context} context The context.
   * @private
   */
  AutoExposure.prototype.clear = function (context) {
    var framebuffers = this._framebuffers;
    if (!defined(framebuffers)) {
      return;
    }

    var clearCommand = this._clearCommand;
    if (!defined(clearCommand)) {
      clearCommand = this._clearCommand = new ClearCommand({
        color: new Color(0.0, 0.0, 0.0, 0.0),
        framebuffer: undefined,
      });
    }

    var length = framebuffers.length;
    for (var i = 0; i < length; ++i) {
      clearCommand.framebuffer = framebuffers[i];
      clearCommand.execute(context);
    }
  };

  /**
   * A function that will be called before execute. Used to create WebGL resources and load any textures.
   * @param {Context} context The context.
   * @private
   */
  AutoExposure.prototype.update = function (context) {
    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight;

    if (width !== this._width || height !== this._height) {
      this._width = width;
      this._height = height;

      createFramebuffers(this, context);
      createCommands$5(this, context);

      if (!this._ready) {
        this._ready = true;
      }
    }

    this._minMaxLuminance.x = this.minimumLuminance;
    this._minMaxLuminance.y = this.maximumLuminance;

    var framebuffers = this._framebuffers;
    var temp = framebuffers[framebuffers.length - 1];
    framebuffers[framebuffers.length - 1] = this._previousLuminance;
    this._commands[
      this._commands.length - 1
    ].framebuffer = this._previousLuminance;
    this._previousLuminance = temp;
  };

  /**
   * Executes the post-process stage. The color texture is the texture rendered to by the scene or from the previous stage.
   * @param {Context} context The context.
   * @param {Texture} colorTexture The input color texture.
   * @private
   */
  AutoExposure.prototype.execute = function (context, colorTexture) {
    this._colorTexture = colorTexture;

    var commands = this._commands;
    if (!defined(commands)) {
      return;
    }

    var length = commands.length;
    for (var i = 0; i < length; ++i) {
      commands[i].execute(context);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see AutoExposure#destroy
   */
  AutoExposure.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see AutoExposure#isDestroyed
   */
  AutoExposure.prototype.destroy = function () {
    destroyFramebuffers(this);
    destroyCommands(this);
    return destroyObject(this);
  };

  /**
   * The types of imagery provided by Bing Maps.
   *
   * @enum {Number}
   *
   * @see BingMapsImageryProvider
   */
  var BingMapsStyle = {
    /**
     * Aerial imagery.
     *
     * @type {String}
     * @constant
     */
    AERIAL: "Aerial",

    /**
     * Aerial imagery with a road overlay.
     *
     * @type {String}
     * @constant
     * @deprecated See https://github.com/CesiumGS/cesium/issues/7128.
     * Use `BingMapsStyle.AERIAL_WITH_LABELS_ON_DEMAND` instead
     */
    AERIAL_WITH_LABELS: "AerialWithLabels",

    /**
     * Aerial imagery with a road overlay.
     *
     * @type {String}
     * @constant
     */
    AERIAL_WITH_LABELS_ON_DEMAND: "AerialWithLabelsOnDemand",

    /**
     * Roads without additional imagery.
     *
     * @type {String}
     * @constant
     * @deprecated See https://github.com/CesiumGS/cesium/issues/7128.
     * Use `BingMapsStyle.ROAD_ON_DEMAND` instead
     */
    ROAD: "Road",

    /**
     * Roads without additional imagery.
     *
     * @type {String}
     * @constant
     */
    ROAD_ON_DEMAND: "RoadOnDemand",

    /**
     * A dark version of the road maps.
     *
     * @type {String}
     * @constant
     */
    CANVAS_DARK: "CanvasDark",

    /**
     * A lighter version of the road maps.
     *
     * @type {String}
     * @constant
     */
    CANVAS_LIGHT: "CanvasLight",

    /**
     * A grayscale version of the road maps.
     *
     * @type {String}
     * @constant
     */
    CANVAS_GRAY: "CanvasGray",

    /**
     * Ordnance Survey imagery. This imagery is visible only for the London, UK area.
     *
     * @type {String}
     * @constant
     */
    ORDNANCE_SURVEY: "OrdnanceSurvey",

    /**
     * Collins Bart imagery.
     *
     * @type {String}
     * @constant
     */
    COLLINS_BART: "CollinsBart",
  };
  var BingMapsStyle$1 = Object.freeze(BingMapsStyle);

  /**
   * A policy for discarding tile images that contain no data (and so aren't actually images).
   * This policy discards {@link DiscardEmptyTileImagePolicy.EMPTY_IMAGE}, which is
   * expected to be used in place of any empty tile images by the image loading code.
   *
   * @alias DiscardEmptyTileImagePolicy
   * @constructor
   *
   * @see DiscardMissingTileImagePolicy
   */
  function DiscardEmptyTileImagePolicy(options) {}

  /**
   * Determines if the discard policy is ready to process images.
   * @returns {Boolean} True if the discard policy is ready to process images; otherwise, false.
   */
  DiscardEmptyTileImagePolicy.prototype.isReady = function () {
    return true;
  };

  /**
   * Given a tile image, decide whether to discard that image.
   *
   * @param {HTMLImageElement} image An image to test.
   * @returns {Boolean} True if the image should be discarded; otherwise, false.
   */
  DiscardEmptyTileImagePolicy.prototype.shouldDiscardImage = function (image) {
    return DiscardEmptyTileImagePolicy.EMPTY_IMAGE === image;
  };

  var emptyImage;

  Object.defineProperties(DiscardEmptyTileImagePolicy, {
    /**
     * Default value for representing an empty image.
     * @type {HTMLImageElement}
     * @readonly
     * @memberof DiscardEmptyTileImagePolicy
     */
    EMPTY_IMAGE: {
      get: function () {
        if (!defined(emptyImage)) {
          emptyImage = new Image();
          // load a blank data URI with a 1x1 transparent pixel.
          emptyImage.src =
            "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=";
        }
        return emptyImage;
      },
    },
  });

  /**
   * @typedef {Object} BingMapsImageryProvider.ConstructorOptions
   *
   * Initialization options for the BingMapsImageryProvider constructor
   *
   * @property {Resource|String} url The url of the Bing Maps server hosting the imagery.
   * @property {String} key The Bing Maps key for your application, which can be
   *        created at {@link https://www.bingmapsportal.com/}.
   *        If this parameter is not provided, {@link BingMapsApi.defaultKey} is used, which is undefined by default.
   * @property {String} [tileProtocol] The protocol to use when loading tiles, e.g. 'http' or 'https'.
   *        By default, tiles are loaded using the same protocol as the page.
   * @property {BingMapsStyle} [mapStyle=BingMapsStyle.AERIAL] The type of Bing Maps imagery to load.
   * @property {String} [culture=''] The culture to use when requesting Bing Maps imagery. Not
   *        all cultures are supported. See {@link http://msdn.microsoft.com/en-us/library/hh441729.aspx}
   *        for information on the supported cultures.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @property {TileDiscardPolicy} [tileDiscardPolicy] The policy that determines if a tile
   *        is invalid and should be discarded.  By default, a {@link DiscardEmptyTileImagePolicy}
   *        will be used, with the expectation that the Bing Maps server will send a zero-length response for missing tiles.
   *        To ensure that no tiles are discarded, construct and pass a {@link NeverTileDiscardPolicy} for this parameter.
   */

  /**
   * Provides tiled imagery using the Bing Maps Imagery REST API.
   *
   * @alias BingMapsImageryProvider
   * @constructor
   *
   * @param {BingMapsImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @see ArcGisMapServerImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   *
   * @example
   * var bing = new Cesium.BingMapsImageryProvider({
   *     url : 'https://dev.virtualearth.net',
   *     key : 'get-yours-at-https://www.bingmapsportal.com/',
   *     mapStyle : Cesium.BingMapsStyle.AERIAL
   * });
   *
   * @see {@link http://msdn.microsoft.com/en-us/library/ff701713.aspx|Bing Maps REST Services}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  function BingMapsImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var accessKey = BingMapsApi._getKeyNoDeprecate(options.key);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    if (!defined(accessKey)) {
      throw new DeveloperError("options.key is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default 1.0
     */
    this.defaultGamma = 1.0;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    this._key = accessKey;
    this._resource = Resource.createIfNeeded(options.url);
    this._resource.appendForwardSlash();
    this._tileProtocol = options.tileProtocol;
    this._mapStyle = defaultValue(options.mapStyle, BingMapsStyle$1.AERIAL);
    this._culture = defaultValue(options.culture, "");

    this._tileDiscardPolicy = options.tileDiscardPolicy;
    if (!defined(this._tileDiscardPolicy)) {
      this._tileDiscardPolicy = new DiscardEmptyTileImagePolicy();
    }

    this._proxy = options.proxy;
    this._credit = new Credit(
      '<a href="http://www.bing.com"><img src="' +
        BingMapsImageryProvider.logoUrl +
        '" title="Bing Imagery"/></a>'
    );

    this._tilingScheme = new WebMercatorTilingScheme({
      numberOfLevelZeroTilesX: 2,
      numberOfLevelZeroTilesY: 2,
      ellipsoid: options.ellipsoid,
    });

    this._tileWidth = undefined;
    this._tileHeight = undefined;
    this._maximumLevel = undefined;
    this._imageUrlTemplate = undefined;
    this._imageUrlSubdomains = undefined;

    this._errorEvent = new Event();

    this._ready = false;
    this._readyPromise = when.defer();

    var tileProtocol = this._tileProtocol;

    // For backward compatibility reasons, the tileProtocol may end with
    // a `:`. Remove it.
    if (defined(tileProtocol)) {
      if (
        tileProtocol.length > 0 &&
        tileProtocol[tileProtocol.length - 1] === ":"
      ) {
        tileProtocol = tileProtocol.substr(0, tileProtocol.length - 1);
      }
    } else {
      // use http if the document's protocol is http, otherwise use https
      var documentProtocol = document.location.protocol;
      tileProtocol = documentProtocol === "http:" ? "http" : "https";
    }

    var metadataResource = this._resource.getDerivedResource({
      url: "REST/v1/Imagery/Metadata/" + this._mapStyle,
      queryParameters: {
        incl: "ImageryProviders",
        key: this._key,
        uriScheme: tileProtocol,
      },
    });
    var that = this;
    var metadataError;

    function metadataSuccess(data) {
      if (data.resourceSets.length !== 1) {
        metadataFailure();
        return;
      }
      var resource = data.resourceSets[0].resources[0];

      that._tileWidth = resource.imageWidth;
      that._tileHeight = resource.imageHeight;
      that._maximumLevel = resource.zoomMax - 1;
      that._imageUrlSubdomains = resource.imageUrlSubdomains;
      that._imageUrlTemplate = resource.imageUrl;

      var attributionList = (that._attributionList = resource.imageryProviders);
      if (!attributionList) {
        attributionList = that._attributionList = [];
      }

      for (
        var attributionIndex = 0, attributionLength = attributionList.length;
        attributionIndex < attributionLength;
        ++attributionIndex
      ) {
        var attribution = attributionList[attributionIndex];

        if (attribution.credit instanceof Credit) {
          // If attribution.credit has already been created
          // then we are using a cached value, which means
          // none of the remaining processing needs to be done.
          break;
        }

        attribution.credit = new Credit(attribution.attribution);
        var coverageAreas = attribution.coverageAreas;

        for (
          var areaIndex = 0, areaLength = attribution.coverageAreas.length;
          areaIndex < areaLength;
          ++areaIndex
        ) {
          var area = coverageAreas[areaIndex];
          var bbox = area.bbox;
          area.bbox = new Rectangle(
            CesiumMath.toRadians(bbox[1]),
            CesiumMath.toRadians(bbox[0]),
            CesiumMath.toRadians(bbox[3]),
            CesiumMath.toRadians(bbox[2])
          );
        }
      }

      that._ready = true;
      that._readyPromise.resolve(true);
      TileProviderError.handleSuccess(metadataError);
    }

    function metadataFailure(e) {
      var message =
        "An error occurred while accessing " + metadataResource.url + ".";
      metadataError = TileProviderError.handleError(
        metadataError,
        that,
        that._errorEvent,
        message,
        undefined,
        undefined,
        undefined,
        requestMetadata
      );
      that._readyPromise.reject(new RuntimeError(message));
    }

    var cacheKey = metadataResource.url;
    function requestMetadata() {
      var promise = metadataResource.fetchJsonp("jsonp");
      BingMapsImageryProvider._metadataCache[cacheKey] = promise;
      promise.then(metadataSuccess).otherwise(metadataFailure);
    }

    var promise = BingMapsImageryProvider._metadataCache[cacheKey];
    if (defined(promise)) {
      promise.then(metadataSuccess).otherwise(metadataFailure);
    } else {
      requestMetadata();
    }
  }

  Object.defineProperties(BingMapsImageryProvider.prototype, {
    /**
     * Gets the name of the BingMaps server url hosting the imagery.
     * @memberof BingMapsImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource.url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the Bing Maps key.
     * @memberof BingMapsImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    key: {
      get: function () {
        return this._key;
      },
    },

    /**
     * Gets the type of Bing Maps imagery to load.
     * @memberof BingMapsImageryProvider.prototype
     * @type {BingMapsStyle}
     * @readonly
     */
    mapStyle: {
      get: function () {
        return this._mapStyle;
      },
    },

    /**
     * The culture to use when requesting Bing Maps imagery. Not
     * all cultures are supported. See {@link http://msdn.microsoft.com/en-us/library/hh441729.aspx}
     * for information on the supported cultures.
     * @memberof BingMapsImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    culture: {
      get: function () {
        return this._culture;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return 0;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "rectangle must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link BingMapsImageryProvider#ready} returns true.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  Setting this property to false reduces memory usage
     * and texture upload time.
     * @memberof BingMapsImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return false;
      },
    },
  });

  var rectangleScratch$5 = new Rectangle();

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  BingMapsImageryProvider.prototype.getTileCredits = function (x, y, level) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "getTileCredits must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    var rectangle = this._tilingScheme.tileXYToRectangle(
      x,
      y,
      level,
      rectangleScratch$5
    );
    var result = getRectangleAttribution(this._attributionList, level, rectangle);

    return result;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link BingMapsImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  BingMapsImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    var promise = ImageryProvider.loadImage(
      this,
      buildImageResource$1(this, x, y, level, request)
    );

    if (defined(promise)) {
      return promise.otherwise(function (error) {
        // One cause of an error here is that the image we tried to load was zero-length.
        // This isn't actually a problem, since it indicates that there is no tile.
        // So, in that case we return the EMPTY_IMAGE sentinel value for later discarding.
        if (defined(error.blob) && error.blob.size === 0) {
          return DiscardEmptyTileImagePolicy.EMPTY_IMAGE;
        }
        return when.reject(error);
      });
    }

    return undefined;
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  BingMapsImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  /**
   * Converts a tiles (x, y, level) position into a quadkey used to request an image
   * from a Bing Maps server.
   *
   * @param {Number} x The tile's x coordinate.
   * @param {Number} y The tile's y coordinate.
   * @param {Number} level The tile's zoom level.
   *
   * @see {@link http://msdn.microsoft.com/en-us/library/bb259689.aspx|Bing Maps Tile System}
   * @see BingMapsImageryProvider#quadKeyToTileXY
   */
  BingMapsImageryProvider.tileXYToQuadKey = function (x, y, level) {
    var quadkey = "";
    for (var i = level; i >= 0; --i) {
      var bitmask = 1 << i;
      var digit = 0;

      if ((x & bitmask) !== 0) {
        digit |= 1;
      }

      if ((y & bitmask) !== 0) {
        digit |= 2;
      }

      quadkey += digit;
    }
    return quadkey;
  };

  /**
   * Converts a tile's quadkey used to request an image from a Bing Maps server into the
   * (x, y, level) position.
   *
   * @param {String} quadkey The tile's quad key
   *
   * @see {@link http://msdn.microsoft.com/en-us/library/bb259689.aspx|Bing Maps Tile System}
   * @see BingMapsImageryProvider#tileXYToQuadKey
   */
  BingMapsImageryProvider.quadKeyToTileXY = function (quadkey) {
    var x = 0;
    var y = 0;
    var level = quadkey.length - 1;
    for (var i = level; i >= 0; --i) {
      var bitmask = 1 << i;
      var digit = +quadkey[level - i];

      if ((digit & 1) !== 0) {
        x |= bitmask;
      }

      if ((digit & 2) !== 0) {
        y |= bitmask;
      }
    }
    return {
      x: x,
      y: y,
      level: level,
    };
  };

  BingMapsImageryProvider._logoUrl = undefined;

  Object.defineProperties(BingMapsImageryProvider, {
    /**
     * Gets or sets the URL to the Bing logo for display in the credit.
     * @memberof BingMapsImageryProvider
     * @type {String}
     */
    logoUrl: {
      get: function () {
        if (!defined(BingMapsImageryProvider._logoUrl)) {
          BingMapsImageryProvider._logoUrl = buildModuleUrl(
            "Assets/Images/bing_maps_credit.png"
          );
        }
        return BingMapsImageryProvider._logoUrl;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');

        BingMapsImageryProvider._logoUrl = value;
      },
    },
  });

  function buildImageResource$1(imageryProvider, x, y, level, request) {
    var imageUrl = imageryProvider._imageUrlTemplate;

    var subdomains = imageryProvider._imageUrlSubdomains;
    var subdomainIndex = (x + y + level) % subdomains.length;

    return imageryProvider._resource.getDerivedResource({
      url: imageUrl,
      request: request,
      templateValues: {
        quadkey: BingMapsImageryProvider.tileXYToQuadKey(x, y, level),
        subdomain: subdomains[subdomainIndex],
        culture: imageryProvider._culture,
      },
      queryParameters: {
        // this parameter tells the Bing servers to send a zero-length response
        // instead of a placeholder image for missing tiles.
        n: "z",
      },
    });
  }

  var intersectionScratch$1 = new Rectangle();

  function getRectangleAttribution(attributionList, level, rectangle) {
    // Bing levels start at 1, while ours start at 0.
    ++level;

    var result = [];

    for (
      var attributionIndex = 0, attributionLength = attributionList.length;
      attributionIndex < attributionLength;
      ++attributionIndex
    ) {
      var attribution = attributionList[attributionIndex];
      var coverageAreas = attribution.coverageAreas;

      var included = false;

      for (
        var areaIndex = 0, areaLength = attribution.coverageAreas.length;
        !included && areaIndex < areaLength;
        ++areaIndex
      ) {
        var area = coverageAreas[areaIndex];
        if (level >= area.zoomMin && level <= area.zoomMax) {
          var intersection = Rectangle.intersection(
            rectangle,
            area.bbox,
            intersectionScratch$1
          );
          if (defined(intersection)) {
            included = true;
          }
        }
      }

      if (included) {
        result.push(attribution.credit);
      }
    }

    return result;
  }

  // Exposed for testing
  BingMapsImageryProvider._metadataCache = {};

  var defaultDimensions = new Cartesian3(1.0, 1.0, 1.0);

  /**
   * A ParticleEmitter that emits particles within a box.
   * Particles will be positioned randomly within the box and have initial velocities emanating from the center of the box.
   *
   * @alias BoxEmitter
   * @constructor
   *
   * @param {Cartesian3} dimensions The width, height and depth dimensions of the box.
   */
  function BoxEmitter(dimensions) {
    dimensions = defaultValue(dimensions, defaultDimensions);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("dimensions", dimensions);
    Check.typeOf.number.greaterThanOrEquals("dimensions.x", dimensions.x, 0.0);
    Check.typeOf.number.greaterThanOrEquals("dimensions.y", dimensions.y, 0.0);
    Check.typeOf.number.greaterThanOrEquals("dimensions.z", dimensions.z, 0.0);
    //>>includeEnd('debug');

    this._dimensions = Cartesian3.clone(dimensions);
  }

  Object.defineProperties(BoxEmitter.prototype, {
    /**
     * The width, height and depth dimensions of the box in meters.
     * @memberof BoxEmitter.prototype
     * @type {Cartesian3}
     * @default new Cartesian3(1.0, 1.0, 1.0)
     */
    dimensions: {
      get: function () {
        return this._dimensions;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        Check.typeOf.number.greaterThanOrEquals("value.x", value.x, 0.0);
        Check.typeOf.number.greaterThanOrEquals("value.y", value.y, 0.0);
        Check.typeOf.number.greaterThanOrEquals("value.z", value.z, 0.0);
        //>>includeEnd('debug');
        Cartesian3.clone(value, this._dimensions);
      },
    },
  });

  var scratchHalfDim = new Cartesian3();

  /**
   * Initializes the given {Particle} by setting it's position and velocity.
   *
   * @private
   * @param {Particle} particle The particle to initialize.
   */
  BoxEmitter.prototype.emit = function (particle) {
    var dim = this._dimensions;
    var halfDim = Cartesian3.multiplyByScalar(dim, 0.5, scratchHalfDim);

    var x = CesiumMath.randomBetween(-halfDim.x, halfDim.x);
    var y = CesiumMath.randomBetween(-halfDim.y, halfDim.y);
    var z = CesiumMath.randomBetween(-halfDim.z, halfDim.z);

    particle.position = Cartesian3.fromElements(x, y, z, particle.position);
    particle.velocity = Cartesian3.normalize(
      particle.position,
      particle.velocity
    );
  };

  //This file is automatically rebuilt by the Cesium build process.
  var BrdfLutGeneratorFS = "varying vec2 v_textureCoordinates;\n\
const float M_PI = 3.141592653589793;\n\
float vdcRadicalInverse(int i)\n\
{\n\
float r;\n\
float base = 2.0;\n\
float value = 0.0;\n\
float invBase = 1.0 / base;\n\
float invBi = invBase;\n\
for (int x = 0; x < 100; x++)\n\
{\n\
if (i <= 0)\n\
{\n\
break;\n\
}\n\
r = mod(float(i), base);\n\
value += r * invBi;\n\
invBi *= invBase;\n\
i = int(float(i) * invBase);\n\
}\n\
return value;\n\
}\n\
vec2 hammersley2D(int i, int N)\n\
{\n\
return vec2(float(i) / float(N), vdcRadicalInverse(i));\n\
}\n\
vec3 importanceSampleGGX(vec2 xi, float roughness, vec3 N)\n\
{\n\
float a = roughness * roughness;\n\
float phi = 2.0 * M_PI * xi.x;\n\
float cosTheta = sqrt((1.0 - xi.y) / (1.0 + (a * a - 1.0) * xi.y));\n\
float sinTheta = sqrt(1.0 - cosTheta * cosTheta);\n\
vec3 H = vec3(sinTheta * cos(phi), sinTheta * sin(phi), cosTheta);\n\
vec3 upVector = abs(N.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);\n\
vec3 tangentX = normalize(cross(upVector, N));\n\
vec3 tangentY = cross(N, tangentX);\n\
return tangentX * H.x + tangentY * H.y + N * H.z;\n\
}\n\
float G1_Smith(float NdotV, float k)\n\
{\n\
return NdotV / (NdotV * (1.0 - k) + k);\n\
}\n\
float G_Smith(float roughness, float NdotV, float NdotL)\n\
{\n\
float k = roughness * roughness / 2.0;\n\
return G1_Smith(NdotV, k) * G1_Smith(NdotL, k);\n\
}\n\
vec2 integrateBrdf(float roughness, float NdotV)\n\
{\n\
vec3 V = vec3(sqrt(1.0 - NdotV * NdotV), 0.0, NdotV);\n\
float A = 0.0;\n\
float B = 0.0;\n\
const int NumSamples = 1024;\n\
for (int i = 0; i < NumSamples; i++)\n\
{\n\
vec2 xi = hammersley2D(i, NumSamples);\n\
vec3 H = importanceSampleGGX(xi, roughness, vec3(0.0, 0.0, 1.0));\n\
vec3 L = 2.0 * dot(V, H) * H - V;\n\
float NdotL = clamp(L.z, 0.0, 1.0);\n\
float NdotH = clamp(H.z, 0.0, 1.0);\n\
float VdotH = clamp(dot(V, H), 0.0, 1.0);\n\
if (NdotL > 0.0)\n\
{\n\
float G = G_Smith(roughness, NdotV, NdotL);\n\
float G_Vis = G * VdotH / (NdotH * NdotV);\n\
float Fc = pow(1.0 - VdotH, 5.0);\n\
A += (1.0 - Fc) * G_Vis;\n\
B += Fc * G_Vis;\n\
}\n\
}\n\
return vec2(A, B) / float(NumSamples);\n\
}\n\
void main()\n\
{\n\
gl_FragColor = vec4(integrateBrdf(v_textureCoordinates.y, v_textureCoordinates.x), 0.0, 1.0);\n\
}\n\
";

  /**
   * @private
   */
  function BrdfLutGenerator() {
    this._framebuffer = undefined;
    this._colorTexture = undefined;
    this._drawCommand = undefined;
  }

  Object.defineProperties(BrdfLutGenerator.prototype, {
    colorTexture: {
      get: function () {
        return this._colorTexture;
      },
    },
  });

  function createCommand$1(generator, context) {
    var framebuffer = generator._framebuffer;

    var drawCommand = context.createViewportQuadCommand(BrdfLutGeneratorFS, {
      framebuffer: framebuffer,
      renderState: RenderState.fromCache({
        viewport: new BoundingRectangle(0.0, 0.0, 256.0, 256.0),
      }),
    });

    generator._drawCommand = drawCommand;
  }

  function createFramebuffer$2(generator, context) {
    var colorTexture = new Texture({
      context: context,
      width: 256,
      height: 256,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    generator._colorTexture = colorTexture;

    var framebuffer = new Framebuffer({
      context: context,
      colorTextures: [colorTexture],
      destroyAttachments: false,
    });

    generator._framebuffer = framebuffer;
  }

  BrdfLutGenerator.prototype.update = function (frameState) {
    if (!defined(this._colorTexture)) {
      var context = frameState.context;

      createFramebuffer$2(this, context);
      createCommand$1(this, context);
      this._drawCommand.execute(context);
      this._framebuffer = this._framebuffer && this._framebuffer.destroy();
      this._drawCommand.shaderProgram =
        this._drawCommand.shaderProgram &&
        this._drawCommand.shaderProgram.destroy();
    }
  };

  BrdfLutGenerator.prototype.isDestroyed = function () {
    return false;
  };

  BrdfLutGenerator.prototype.destroy = function () {
    this._colorTexture = this._colorTexture && this._colorTexture.destroy();
    return destroyObject(this);
  };

  /**
   * Creates tweens for camera flights.
   * <br /><br />
   * Mouse interaction is disabled during flights.
   *
   * @private
   */
  var CameraFlightPath = {};

  function getAltitude(frustum, dx, dy) {
    var near;
    var top;
    var right;
    if (frustum instanceof PerspectiveFrustum) {
      var tanTheta = Math.tan(0.5 * frustum.fovy);
      near = frustum.near;
      top = frustum.near * tanTheta;
      right = frustum.aspectRatio * top;
      return Math.max((dx * near) / right, (dy * near) / top);
    } else if (frustum instanceof PerspectiveOffCenterFrustum) {
      near = frustum.near;
      top = frustum.top;
      right = frustum.right;
      return Math.max((dx * near) / right, (dy * near) / top);
    }

    return Math.max(dx, dy);
  }

  var scratchCart = new Cartesian3();
  var scratchCart2$2 = new Cartesian3();

  function createPitchFunction(
    startPitch,
    endPitch,
    heightFunction,
    pitchAdjustHeight
  ) {
    if (defined(pitchAdjustHeight) && heightFunction(0.5) > pitchAdjustHeight) {
      var startHeight = heightFunction(0.0);
      var endHeight = heightFunction(1.0);
      var middleHeight = heightFunction(0.5);

      var d1 = middleHeight - startHeight;
      var d2 = middleHeight - endHeight;

      return function (time) {
        var altitude = heightFunction(time);
        if (time <= 0.5) {
          var t1 = (altitude - startHeight) / d1;
          return CesiumMath.lerp(startPitch, -CesiumMath.PI_OVER_TWO, t1);
        }

        var t2 = (altitude - endHeight) / d2;
        return CesiumMath.lerp(-CesiumMath.PI_OVER_TWO, endPitch, 1 - t2);
      };
    }
    return function (time) {
      return CesiumMath.lerp(startPitch, endPitch, time);
    };
  }

  function createHeightFunction(
    camera,
    destination,
    startHeight,
    endHeight,
    optionAltitude
  ) {
    var altitude = optionAltitude;
    var maxHeight = Math.max(startHeight, endHeight);

    if (!defined(altitude)) {
      var start = camera.position;
      var end = destination;
      var up = camera.up;
      var right = camera.right;
      var frustum = camera.frustum;

      var diff = Cartesian3.subtract(start, end, scratchCart);
      var verticalDistance = Cartesian3.magnitude(
        Cartesian3.multiplyByScalar(up, Cartesian3.dot(diff, up), scratchCart2$2)
      );
      var horizontalDistance = Cartesian3.magnitude(
        Cartesian3.multiplyByScalar(
          right,
          Cartesian3.dot(diff, right),
          scratchCart2$2
        )
      );

      altitude = Math.min(
        getAltitude(frustum, verticalDistance, horizontalDistance) * 0.2,
        1000000000.0
      );
    }

    if (maxHeight < altitude) {
      var power = 8.0;
      var factor = 1000000.0;

      var s = -Math.pow((altitude - startHeight) * factor, 1.0 / power);
      var e = Math.pow((altitude - endHeight) * factor, 1.0 / power);

      return function (t) {
        var x = t * (e - s) + s;
        return -Math.pow(x, power) / factor + altitude;
      };
    }

    return function (t) {
      return CesiumMath.lerp(startHeight, endHeight, t);
    };
  }

  function adjustAngleForLERP(startAngle, endAngle) {
    if (
      CesiumMath.equalsEpsilon(
        startAngle,
        CesiumMath.TWO_PI,
        CesiumMath.EPSILON11
      )
    ) {
      startAngle = 0.0;
    }

    if (endAngle > startAngle + Math.PI) {
      startAngle += CesiumMath.TWO_PI;
    } else if (endAngle < startAngle - Math.PI) {
      startAngle -= CesiumMath.TWO_PI;
    }

    return startAngle;
  }

  var scratchStart = new Cartesian3();

  function createUpdateCV(
    scene,
    duration,
    destination,
    heading,
    pitch,
    roll,
    optionAltitude
  ) {
    var camera = scene.camera;

    var start = Cartesian3.clone(camera.position, scratchStart);
    var startPitch = camera.pitch;
    var startHeading = adjustAngleForLERP(camera.heading, heading);
    var startRoll = adjustAngleForLERP(camera.roll, roll);

    var heightFunction = createHeightFunction(
      camera,
      destination,
      start.z,
      destination.z,
      optionAltitude
    );

    function update(value) {
      var time = value.time / duration;

      camera.setView({
        orientation: {
          heading: CesiumMath.lerp(startHeading, heading, time),
          pitch: CesiumMath.lerp(startPitch, pitch, time),
          roll: CesiumMath.lerp(startRoll, roll, time),
        },
      });

      Cartesian2.lerp(start, destination, time, camera.position);
      camera.position.z = heightFunction(time);
    }
    return update;
  }

  function useLongestFlight(startCart, destCart) {
    if (startCart.longitude < destCart.longitude) {
      startCart.longitude += CesiumMath.TWO_PI;
    } else {
      destCart.longitude += CesiumMath.TWO_PI;
    }
  }

  function useShortestFlight(startCart, destCart) {
    var diff = startCart.longitude - destCart.longitude;
    if (diff < -CesiumMath.PI) {
      startCart.longitude += CesiumMath.TWO_PI;
    } else if (diff > CesiumMath.PI) {
      destCart.longitude += CesiumMath.TWO_PI;
    }
  }

  var scratchStartCart = new Cartographic();
  var scratchEndCart = new Cartographic();

  function createUpdate3D(
    scene,
    duration,
    destination,
    heading,
    pitch,
    roll,
    optionAltitude,
    optionFlyOverLongitude,
    optionFlyOverLongitudeWeight,
    optionPitchAdjustHeight
  ) {
    var camera = scene.camera;
    var projection = scene.mapProjection;
    var ellipsoid = projection.ellipsoid;

    var startCart = Cartographic.clone(
      camera.positionCartographic,
      scratchStartCart
    );
    var startPitch = camera.pitch;
    var startHeading = adjustAngleForLERP(camera.heading, heading);
    var startRoll = adjustAngleForLERP(camera.roll, roll);

    var destCart = ellipsoid.cartesianToCartographic(destination, scratchEndCart);
    startCart.longitude = CesiumMath.zeroToTwoPi(startCart.longitude);
    destCart.longitude = CesiumMath.zeroToTwoPi(destCart.longitude);

    var useLongFlight = false;

    if (defined(optionFlyOverLongitude)) {
      var hitLon = CesiumMath.zeroToTwoPi(optionFlyOverLongitude);

      var lonMin = Math.min(startCart.longitude, destCart.longitude);
      var lonMax = Math.max(startCart.longitude, destCart.longitude);

      var hitInside = hitLon >= lonMin && hitLon <= lonMax;

      if (defined(optionFlyOverLongitudeWeight)) {
        // Distance inside  (0...2Pi)
        var din = Math.abs(startCart.longitude - destCart.longitude);
        // Distance outside (0...2Pi)
        var dot = CesiumMath.TWO_PI - din;

        var hitDistance = hitInside ? din : dot;
        var offDistance = hitInside ? dot : din;

        if (
          hitDistance < offDistance * optionFlyOverLongitudeWeight &&
          !hitInside
        ) {
          useLongFlight = true;
        }
      } else if (!hitInside) {
        useLongFlight = true;
      }
    }

    if (useLongFlight) {
      useLongestFlight(startCart, destCart);
    } else {
      useShortestFlight(startCart, destCart);
    }

    var heightFunction = createHeightFunction(
      camera,
      destination,
      startCart.height,
      destCart.height,
      optionAltitude
    );
    var pitchFunction = createPitchFunction(
      startPitch,
      pitch,
      heightFunction,
      optionPitchAdjustHeight
    );

    // Isolate scope for update function.
    // to have local copies of vars used in lerp
    // Othervise, if you call nex
    // createUpdate3D (createAnimationTween)
    // before you played animation, variables will be overwriten.
    function isolateUpdateFunction() {
      var startLongitude = startCart.longitude;
      var destLongitude = destCart.longitude;
      var startLatitude = startCart.latitude;
      var destLatitude = destCart.latitude;

      return function update(value) {
        var time = value.time / duration;

        var position = Cartesian3.fromRadians(
          CesiumMath.lerp(startLongitude, destLongitude, time),
          CesiumMath.lerp(startLatitude, destLatitude, time),
          heightFunction(time)
        );

        camera.setView({
          destination: position,
          orientation: {
            heading: CesiumMath.lerp(startHeading, heading, time),
            pitch: pitchFunction(time),
            roll: CesiumMath.lerp(startRoll, roll, time),
          },
        });
      };
    }
    return isolateUpdateFunction();
  }

  function createUpdate2D(
    scene,
    duration,
    destination,
    heading,
    pitch,
    roll,
    optionAltitude
  ) {
    var camera = scene.camera;

    var start = Cartesian3.clone(camera.position, scratchStart);
    var startHeading = adjustAngleForLERP(camera.heading, heading);

    var startHeight = camera.frustum.right - camera.frustum.left;
    var heightFunction = createHeightFunction(
      camera,
      destination,
      startHeight,
      destination.z,
      optionAltitude
    );

    function update(value) {
      var time = value.time / duration;

      camera.setView({
        orientation: {
          heading: CesiumMath.lerp(startHeading, heading, time),
        },
      });

      Cartesian2.lerp(start, destination, time, camera.position);

      var zoom = heightFunction(time);

      var frustum = camera.frustum;
      var ratio = frustum.top / frustum.right;

      var incrementAmount = (zoom - (frustum.right - frustum.left)) * 0.5;
      frustum.right += incrementAmount;
      frustum.left -= incrementAmount;
      frustum.top = ratio * frustum.right;
      frustum.bottom = -frustum.top;
    }
    return update;
  }

  var scratchCartographic$b = new Cartographic();
  var scratchDestination = new Cartesian3();

  function emptyFlight(complete, cancel) {
    return {
      startObject: {},
      stopObject: {},
      duration: 0.0,
      complete: complete,
      cancel: cancel,
    };
  }

  function wrapCallback(controller, cb) {
    function wrapped() {
      if (typeof cb === "function") {
        cb();
      }

      controller.enableInputs = true;
    }
    return wrapped;
  }

  CameraFlightPath.createTween = function (scene, options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var destination = options.destination;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    if (!defined(destination)) {
      throw new DeveloperError("destination is required.");
    }
    //>>includeEnd('debug');
    var mode = scene.mode;

    if (mode === SceneMode$1.MORPHING) {
      return emptyFlight();
    }

    var convert = defaultValue(options.convert, true);
    var projection = scene.mapProjection;
    var ellipsoid = projection.ellipsoid;
    var maximumHeight = options.maximumHeight;
    var flyOverLongitude = options.flyOverLongitude;
    var flyOverLongitudeWeight = options.flyOverLongitudeWeight;
    var pitchAdjustHeight = options.pitchAdjustHeight;
    var easingFunction = options.easingFunction;

    if (convert && mode !== SceneMode$1.SCENE3D) {
      ellipsoid.cartesianToCartographic(destination, scratchCartographic$b);
      destination = projection.project(scratchCartographic$b, scratchDestination);
    }

    var camera = scene.camera;
    var transform = options.endTransform;
    if (defined(transform)) {
      camera._setTransform(transform);
    }

    var duration = options.duration;
    if (!defined(duration)) {
      duration =
        Math.ceil(Cartesian3.distance(camera.position, destination) / 1000000.0) +
        2.0;
      duration = Math.min(duration, 3.0);
    }

    var heading = defaultValue(options.heading, 0.0);
    var pitch = defaultValue(options.pitch, -CesiumMath.PI_OVER_TWO);
    var roll = defaultValue(options.roll, 0.0);

    var controller = scene.screenSpaceCameraController;
    controller.enableInputs = false;

    var complete = wrapCallback(controller, options.complete);
    var cancel = wrapCallback(controller, options.cancel);

    var frustum = camera.frustum;

    var empty = scene.mode === SceneMode$1.SCENE2D;
    empty =
      empty &&
      Cartesian2.equalsEpsilon(camera.position, destination, CesiumMath.EPSILON6);
    empty =
      empty &&
      CesiumMath.equalsEpsilon(
        Math.max(frustum.right - frustum.left, frustum.top - frustum.bottom),
        destination.z,
        CesiumMath.EPSILON6
      );

    empty =
      empty ||
      (scene.mode !== SceneMode$1.SCENE2D &&
        Cartesian3.equalsEpsilon(
          destination,
          camera.position,
          CesiumMath.EPSILON10
        ));

    empty =
      empty &&
      CesiumMath.equalsEpsilon(
        CesiumMath.negativePiToPi(heading),
        CesiumMath.negativePiToPi(camera.heading),
        CesiumMath.EPSILON10
      ) &&
      CesiumMath.equalsEpsilon(
        CesiumMath.negativePiToPi(pitch),
        CesiumMath.negativePiToPi(camera.pitch),
        CesiumMath.EPSILON10
      ) &&
      CesiumMath.equalsEpsilon(
        CesiumMath.negativePiToPi(roll),
        CesiumMath.negativePiToPi(camera.roll),
        CesiumMath.EPSILON10
      );

    if (empty) {
      return emptyFlight(complete, cancel);
    }

    var updateFunctions = new Array(4);
    updateFunctions[SceneMode$1.SCENE2D] = createUpdate2D;
    updateFunctions[SceneMode$1.SCENE3D] = createUpdate3D;
    updateFunctions[SceneMode$1.COLUMBUS_VIEW] = createUpdateCV;

    if (duration <= 0.0) {
      var newOnComplete = function () {
        var update = updateFunctions[mode](
          scene,
          1.0,
          destination,
          heading,
          pitch,
          roll,
          maximumHeight,
          flyOverLongitude,
          flyOverLongitudeWeight,
          pitchAdjustHeight
        );
        update({ time: 1.0 });

        if (typeof complete === "function") {
          complete();
        }
      };
      return emptyFlight(newOnComplete, cancel);
    }

    var update = updateFunctions[mode](
      scene,
      duration,
      destination,
      heading,
      pitch,
      roll,
      maximumHeight,
      flyOverLongitude,
      flyOverLongitudeWeight,
      pitchAdjustHeight
    );

    if (!defined(easingFunction)) {
      var startHeight = camera.positionCartographic.height;
      var endHeight =
        mode === SceneMode$1.SCENE3D
          ? ellipsoid.cartesianToCartographic(destination).height
          : destination.z;

      if (startHeight > endHeight && startHeight > 11500.0) {
        easingFunction = EasingFunction$1.CUBIC_OUT;
      } else {
        easingFunction = EasingFunction$1.QUINTIC_IN_OUT;
      }
    }

    return {
      duration: duration,
      easingFunction: easingFunction,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: duration,
      },
      update: update,
      complete: complete,
      cancel: cancel,
    };
  };

  /**
   * Describes how the map will operate in 2D.
   *
   * @enum {Number}
   */
  var MapMode2D = {
    /**
     * The 2D map can be rotated about the z axis.
     *
     * @type {Number}
     * @constant
     */
    ROTATE: 0,

    /**
     * The 2D map can be scrolled infinitely in the horizontal direction.
     *
     * @type {Number}
     * @constant
     */
    INFINITE_SCROLL: 1,
  };
  var MapMode2D$1 = Object.freeze(MapMode2D);

  /**
   * The camera is defined by a position, orientation, and view frustum.
   * <br /><br />
   * The orientation forms an orthonormal basis with a view, up and right = view x up unit vectors.
   * <br /><br />
   * The viewing frustum is defined by 6 planes.
   * Each plane is represented by a {@link Cartesian4} object, where the x, y, and z components
   * define the unit vector normal to the plane, and the w component is the distance of the
   * plane from the origin/camera position.
   *
   * @alias Camera
   *
   * @constructor
   *
   * @param {Scene} scene The scene.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Camera.html|Cesium Sandcastle Camera Demo}
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Camera%20Tutorial.html|Cesium Sandcastle Camera Tutorial Example}
   * @demo {@link https://cesium.com/docs/tutorials/camera/|Camera Tutorial}
   *
   * @example
   * // Create a camera looking down the negative z-axis, positioned at the origin,
   * // with a field of view of 60 degrees, and 1:1 aspect ratio.
   * var camera = new Cesium.Camera(scene);
   * camera.position = new Cesium.Cartesian3();
   * camera.direction = Cesium.Cartesian3.negate(Cesium.Cartesian3.UNIT_Z, new Cesium.Cartesian3());
   * camera.up = Cesium.Cartesian3.clone(Cesium.Cartesian3.UNIT_Y);
   * camera.frustum.fov = Cesium.Math.PI_OVER_THREE;
   * camera.frustum.near = 1.0;
   * camera.frustum.far = 2.0;
   */
  function Camera(scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');
    this._scene = scene;

    this._transform = Matrix4.clone(Matrix4.IDENTITY);
    this._invTransform = Matrix4.clone(Matrix4.IDENTITY);
    this._actualTransform = Matrix4.clone(Matrix4.IDENTITY);
    this._actualInvTransform = Matrix4.clone(Matrix4.IDENTITY);
    this._transformChanged = false;

    /**
     * The position of the camera.
     *
     * @type {Cartesian3}
     */
    this.position = new Cartesian3();
    this._position = new Cartesian3();
    this._positionWC = new Cartesian3();
    this._positionCartographic = new Cartographic();
    this._oldPositionWC = undefined;

    /**
     * The position delta magnitude.
     *
     * @private
     */
    this.positionWCDeltaMagnitude = 0.0;

    /**
     * The position delta magnitude last frame.
     *
     * @private
     */
    this.positionWCDeltaMagnitudeLastFrame = 0.0;

    /**
     * How long in seconds since the camera has stopped moving
     *
     * @private
     */
    this.timeSinceMoved = 0.0;
    this._lastMovedTimestamp = 0.0;

    /**
     * The view direction of the camera.
     *
     * @type {Cartesian3}
     */
    this.direction = new Cartesian3();
    this._direction = new Cartesian3();
    this._directionWC = new Cartesian3();

    /**
     * The up direction of the camera.
     *
     * @type {Cartesian3}
     */
    this.up = new Cartesian3();
    this._up = new Cartesian3();
    this._upWC = new Cartesian3();

    /**
     * The right direction of the camera.
     *
     * @type {Cartesian3}
     */
    this.right = new Cartesian3();
    this._right = new Cartesian3();
    this._rightWC = new Cartesian3();

    /**
     * The region of space in view.
     *
     * @type {PerspectiveFrustum|PerspectiveOffCenterFrustum|OrthographicFrustum}
     * @default PerspectiveFrustum()
     *
     * @see PerspectiveFrustum
     * @see PerspectiveOffCenterFrustum
     * @see OrthographicFrustum
     */
    this.frustum = new PerspectiveFrustum();
    this.frustum.aspectRatio =
      scene.drawingBufferWidth / scene.drawingBufferHeight;
    this.frustum.fov = CesiumMath.toRadians(60.0);

    /**
     * The default amount to move the camera when an argument is not
     * provided to the move methods.
     * @type {Number}
     * @default 100000.0;
     */
    this.defaultMoveAmount = 100000.0;
    /**
     * The default amount to rotate the camera when an argument is not
     * provided to the look methods.
     * @type {Number}
     * @default Math.PI / 60.0
     */
    this.defaultLookAmount = Math.PI / 60.0;
    /**
     * The default amount to rotate the camera when an argument is not
     * provided to the rotate methods.
     * @type {Number}
     * @default Math.PI / 3600.0
     */
    this.defaultRotateAmount = Math.PI / 3600.0;
    /**
     * The default amount to move the camera when an argument is not
     * provided to the zoom methods.
     * @type {Number}
     * @default 100000.0;
     */
    this.defaultZoomAmount = 100000.0;
    /**
     * If set, the camera will not be able to rotate past this axis in either direction.
     * @type {Cartesian3}
     * @default undefined
     */
    this.constrainedAxis = undefined;
    /**
     * The factor multiplied by the the map size used to determine where to clamp the camera position
     * when zooming out from the surface. The default is 1.5. Only valid for 2D and the map is rotatable.
     * @type {Number}
     * @default 1.5
     */
    this.maximumZoomFactor = 1.5;

    this._moveStart = new Event();
    this._moveEnd = new Event();

    this._changed = new Event();
    this._changedPosition = undefined;
    this._changedDirection = undefined;
    this._changedFrustum = undefined;

    /**
     * The amount the camera has to change before the <code>changed</code> event is raised. The value is a percentage in the [0, 1] range.
     * @type {number}
     * @default 0.5
     */
    this.percentageChanged = 0.5;

    this._viewMatrix = new Matrix4();
    this._invViewMatrix = new Matrix4();
    updateViewMatrix(this);

    this._mode = SceneMode$1.SCENE3D;
    this._modeChanged = true;
    var projection = scene.mapProjection;
    this._projection = projection;
    this._maxCoord = projection.project(
      new Cartographic(Math.PI, CesiumMath.PI_OVER_TWO)
    );
    this._max2Dfrustum = undefined;

    // set default view
    rectangleCameraPosition3D(
      this,
      Camera.DEFAULT_VIEW_RECTANGLE,
      this.position,
      true
    );

    var mag = Cartesian3.magnitude(this.position);
    mag += mag * Camera.DEFAULT_VIEW_FACTOR;
    Cartesian3.normalize(this.position, this.position);
    Cartesian3.multiplyByScalar(this.position, mag, this.position);
  }

  /**
   * @private
   */
  Camera.TRANSFORM_2D = new Matrix4(
    0.0,
    0.0,
    1.0,
    0.0,
    1.0,
    0.0,
    0.0,
    0.0,
    0.0,
    1.0,
    0.0,
    0.0,
    0.0,
    0.0,
    0.0,
    1.0
  );

  /**
   * @private
   */
  Camera.TRANSFORM_2D_INVERSE = Matrix4.inverseTransformation(
    Camera.TRANSFORM_2D,
    new Matrix4()
  );

  /**
   * The default rectangle the camera will view on creation.
   * @type Rectangle
   */
  Camera.DEFAULT_VIEW_RECTANGLE = Rectangle.fromDegrees(
    -95.0,
    -20.0,
    -70.0,
    90.0
  );

  /**
   * A scalar to multiply to the camera position and add it back after setting the camera to view the rectangle.
   * A value of zero means the camera will view the entire {@link Camera#DEFAULT_VIEW_RECTANGLE}, a value greater than zero
   * will move it further away from the extent, and a value less than zero will move it close to the extent.
   * @type Number
   */
  Camera.DEFAULT_VIEW_FACTOR = 0.5;

  /**
   * The default heading/pitch/range that is used when the camera flies to a location that contains a bounding sphere.
   * @type HeadingPitchRange
   */
  Camera.DEFAULT_OFFSET = new HeadingPitchRange(
    0.0,
    -CesiumMath.PI_OVER_FOUR,
    0.0
  );

  function updateViewMatrix(camera) {
    Matrix4.computeView(
      camera._position,
      camera._direction,
      camera._up,
      camera._right,
      camera._viewMatrix
    );
    Matrix4.multiply(
      camera._viewMatrix,
      camera._actualInvTransform,
      camera._viewMatrix
    );
    Matrix4.inverseTransformation(camera._viewMatrix, camera._invViewMatrix);
  }

  function updateCameraDeltas(camera) {
    if (!defined(camera._oldPositionWC)) {
      camera._oldPositionWC = Cartesian3.clone(
        camera.positionWC,
        camera._oldPositionWC
      );
    } else {
      camera.positionWCDeltaMagnitudeLastFrame = camera.positionWCDeltaMagnitude;
      var delta = Cartesian3.subtract(
        camera.positionWC,
        camera._oldPositionWC,
        camera._oldPositionWC
      );
      camera.positionWCDeltaMagnitude = Cartesian3.magnitude(delta);
      camera._oldPositionWC = Cartesian3.clone(
        camera.positionWC,
        camera._oldPositionWC
      );

      // Update move timers
      if (camera.positionWCDeltaMagnitude > 0.0) {
        camera.timeSinceMoved = 0.0;
        camera._lastMovedTimestamp = getTimestamp$1();
      } else {
        camera.timeSinceMoved =
          Math.max(getTimestamp$1() - camera._lastMovedTimestamp, 0.0) / 1000.0;
      }
    }
  }

  /**
   * Checks if there's a camera flight with preload for this camera.
   *
   * @returns {Boolean} Whether or not this camera has a current flight with a valid preloadFlightCamera in scene.
   *
   * @private
   *
   */
  Camera.prototype.canPreloadFlight = function () {
    return defined(this._currentFlight) && this._mode !== SceneMode$1.SCENE2D;
  };

  Camera.prototype._updateCameraChanged = function () {
    var camera = this;

    updateCameraDeltas(camera);

    if (camera._changed.numberOfListeners === 0) {
      return;
    }

    var percentageChanged = camera.percentageChanged;

    if (camera._mode === SceneMode$1.SCENE2D) {
      if (!defined(camera._changedFrustum)) {
        camera._changedPosition = Cartesian3.clone(
          camera.position,
          camera._changedPosition
        );
        camera._changedFrustum = camera.frustum.clone();
        return;
      }

      var position = camera.position;
      var lastPosition = camera._changedPosition;

      var frustum = camera.frustum;
      var lastFrustum = camera._changedFrustum;

      var x0 = position.x + frustum.left;
      var x1 = position.x + frustum.right;
      var x2 = lastPosition.x + lastFrustum.left;
      var x3 = lastPosition.x + lastFrustum.right;

      var y0 = position.y + frustum.bottom;
      var y1 = position.y + frustum.top;
      var y2 = lastPosition.y + lastFrustum.bottom;
      var y3 = lastPosition.y + lastFrustum.top;

      var leftX = Math.max(x0, x2);
      var rightX = Math.min(x1, x3);
      var bottomY = Math.max(y0, y2);
      var topY = Math.min(y1, y3);

      var areaPercentage;
      if (leftX >= rightX || bottomY >= y1) {
        areaPercentage = 1.0;
      } else {
        var areaRef = lastFrustum;
        if (x0 < x2 && x1 > x3 && y0 < y2 && y1 > y3) {
          areaRef = frustum;
        }
        areaPercentage =
          1.0 -
          ((rightX - leftX) * (topY - bottomY)) /
            ((areaRef.right - areaRef.left) * (areaRef.top - areaRef.bottom));
      }

      if (areaPercentage > percentageChanged) {
        camera._changed.raiseEvent(areaPercentage);
        camera._changedPosition = Cartesian3.clone(
          camera.position,
          camera._changedPosition
        );
        camera._changedFrustum = camera.frustum.clone(camera._changedFrustum);
      }
      return;
    }

    if (!defined(camera._changedDirection)) {
      camera._changedPosition = Cartesian3.clone(
        camera.positionWC,
        camera._changedPosition
      );
      camera._changedDirection = Cartesian3.clone(
        camera.directionWC,
        camera._changedDirection
      );
      return;
    }

    var dirAngle = CesiumMath.acosClamped(
      Cartesian3.dot(camera.directionWC, camera._changedDirection)
    );

    var dirPercentage;
    if (defined(camera.frustum.fovy)) {
      dirPercentage = dirAngle / (camera.frustum.fovy * 0.5);
    } else {
      dirPercentage = dirAngle;
    }

    var distance = Cartesian3.distance(
      camera.positionWC,
      camera._changedPosition
    );
    var heightPercentage = distance / camera.positionCartographic.height;

    if (
      dirPercentage > percentageChanged ||
      heightPercentage > percentageChanged
    ) {
      camera._changed.raiseEvent(Math.max(dirPercentage, heightPercentage));
      camera._changedPosition = Cartesian3.clone(
        camera.positionWC,
        camera._changedPosition
      );
      camera._changedDirection = Cartesian3.clone(
        camera.directionWC,
        camera._changedDirection
      );
    }
  };

  function convertTransformForColumbusView(camera) {
    Transforms.basisTo2D(
      camera._projection,
      camera._transform,
      camera._actualTransform
    );
  }

  var scratchCartographic$c = new Cartographic();
  var scratchCartesian3Projection$1 = new Cartesian3();
  var scratchCartesian3$c = new Cartesian3();
  var scratchCartesian4Origin = new Cartesian4();
  var scratchCartesian4NewOrigin = new Cartesian4();
  var scratchCartesian4NewXAxis = new Cartesian4();
  var scratchCartesian4NewYAxis = new Cartesian4();
  var scratchCartesian4NewZAxis = new Cartesian4();

  function convertTransformFor2D(camera) {
    var projection = camera._projection;
    var ellipsoid = projection.ellipsoid;

    var origin = Matrix4.getColumn(camera._transform, 3, scratchCartesian4Origin);
    var cartographic = ellipsoid.cartesianToCartographic(
      origin,
      scratchCartographic$c
    );

    var projectedPosition = projection.project(
      cartographic,
      scratchCartesian3Projection$1
    );
    var newOrigin = scratchCartesian4NewOrigin;
    newOrigin.x = projectedPosition.z;
    newOrigin.y = projectedPosition.x;
    newOrigin.z = projectedPosition.y;
    newOrigin.w = 1.0;

    var newZAxis = Cartesian4.clone(Cartesian4.UNIT_X, scratchCartesian4NewZAxis);

    var xAxis = Cartesian4.add(
      Matrix4.getColumn(camera._transform, 0, scratchCartesian3$c),
      origin,
      scratchCartesian3$c
    );
    ellipsoid.cartesianToCartographic(xAxis, cartographic);

    projection.project(cartographic, projectedPosition);
    var newXAxis = scratchCartesian4NewXAxis;
    newXAxis.x = projectedPosition.z;
    newXAxis.y = projectedPosition.x;
    newXAxis.z = projectedPosition.y;
    newXAxis.w = 0.0;

    Cartesian3.subtract(newXAxis, newOrigin, newXAxis);
    newXAxis.x = 0.0;

    var newYAxis = scratchCartesian4NewYAxis;
    if (Cartesian3.magnitudeSquared(newXAxis) > CesiumMath.EPSILON10) {
      Cartesian3.cross(newZAxis, newXAxis, newYAxis);
    } else {
      var yAxis = Cartesian4.add(
        Matrix4.getColumn(camera._transform, 1, scratchCartesian3$c),
        origin,
        scratchCartesian3$c
      );
      ellipsoid.cartesianToCartographic(yAxis, cartographic);

      projection.project(cartographic, projectedPosition);
      newYAxis.x = projectedPosition.z;
      newYAxis.y = projectedPosition.x;
      newYAxis.z = projectedPosition.y;
      newYAxis.w = 0.0;

      Cartesian3.subtract(newYAxis, newOrigin, newYAxis);
      newYAxis.x = 0.0;

      if (Cartesian3.magnitudeSquared(newYAxis) < CesiumMath.EPSILON10) {
        Cartesian4.clone(Cartesian4.UNIT_Y, newXAxis);
        Cartesian4.clone(Cartesian4.UNIT_Z, newYAxis);
      }
    }

    Cartesian3.cross(newYAxis, newZAxis, newXAxis);
    Cartesian3.normalize(newXAxis, newXAxis);
    Cartesian3.cross(newZAxis, newXAxis, newYAxis);
    Cartesian3.normalize(newYAxis, newYAxis);

    Matrix4.setColumn(
      camera._actualTransform,
      0,
      newXAxis,
      camera._actualTransform
    );
    Matrix4.setColumn(
      camera._actualTransform,
      1,
      newYAxis,
      camera._actualTransform
    );
    Matrix4.setColumn(
      camera._actualTransform,
      2,
      newZAxis,
      camera._actualTransform
    );
    Matrix4.setColumn(
      camera._actualTransform,
      3,
      newOrigin,
      camera._actualTransform
    );
  }

  var scratchCartesian$8 = new Cartesian3();

  function updateMembers(camera) {
    var mode = camera._mode;

    var heightChanged = false;
    var height = 0.0;
    if (mode === SceneMode$1.SCENE2D) {
      height = camera.frustum.right - camera.frustum.left;
      heightChanged = height !== camera._positionCartographic.height;
    }

    var position = camera._position;
    var positionChanged =
      !Cartesian3.equals(position, camera.position) || heightChanged;
    if (positionChanged) {
      position = Cartesian3.clone(camera.position, camera._position);
    }

    var direction = camera._direction;
    var directionChanged = !Cartesian3.equals(direction, camera.direction);
    if (directionChanged) {
      Cartesian3.normalize(camera.direction, camera.direction);
      direction = Cartesian3.clone(camera.direction, camera._direction);
    }

    var up = camera._up;
    var upChanged = !Cartesian3.equals(up, camera.up);
    if (upChanged) {
      Cartesian3.normalize(camera.up, camera.up);
      up = Cartesian3.clone(camera.up, camera._up);
    }

    var right = camera._right;
    var rightChanged = !Cartesian3.equals(right, camera.right);
    if (rightChanged) {
      Cartesian3.normalize(camera.right, camera.right);
      right = Cartesian3.clone(camera.right, camera._right);
    }

    var transformChanged = camera._transformChanged || camera._modeChanged;
    camera._transformChanged = false;

    if (transformChanged) {
      Matrix4.inverseTransformation(camera._transform, camera._invTransform);

      if (
        camera._mode === SceneMode$1.COLUMBUS_VIEW ||
        camera._mode === SceneMode$1.SCENE2D
      ) {
        if (Matrix4.equals(Matrix4.IDENTITY, camera._transform)) {
          Matrix4.clone(Camera.TRANSFORM_2D, camera._actualTransform);
        } else if (camera._mode === SceneMode$1.COLUMBUS_VIEW) {
          convertTransformForColumbusView(camera);
        } else {
          convertTransformFor2D(camera);
        }
      } else {
        Matrix4.clone(camera._transform, camera._actualTransform);
      }

      Matrix4.inverseTransformation(
        camera._actualTransform,
        camera._actualInvTransform
      );

      camera._modeChanged = false;
    }

    var transform = camera._actualTransform;

    if (positionChanged || transformChanged) {
      camera._positionWC = Matrix4.multiplyByPoint(
        transform,
        position,
        camera._positionWC
      );

      // Compute the Cartographic position of the camera.
      if (mode === SceneMode$1.SCENE3D || mode === SceneMode$1.MORPHING) {
        camera._positionCartographic = camera._projection.ellipsoid.cartesianToCartographic(
          camera._positionWC,
          camera._positionCartographic
        );
      } else {
        // The camera position is expressed in the 2D coordinate system where the Y axis is to the East,
        // the Z axis is to the North, and the X axis is out of the map.  Express them instead in the ENU axes where
        // X is to the East, Y is to the North, and Z is out of the local horizontal plane.
        var positionENU = scratchCartesian$8;
        positionENU.x = camera._positionWC.y;
        positionENU.y = camera._positionWC.z;
        positionENU.z = camera._positionWC.x;

        // In 2D, the camera height is always 12.7 million meters.
        // The apparent height is equal to half the frustum width.
        if (mode === SceneMode$1.SCENE2D) {
          positionENU.z = height;
        }

        camera._projection.unproject(positionENU, camera._positionCartographic);
      }
    }

    if (directionChanged || upChanged || rightChanged) {
      var det = Cartesian3.dot(
        direction,
        Cartesian3.cross(up, right, scratchCartesian$8)
      );
      if (Math.abs(1.0 - det) > CesiumMath.EPSILON2) {
        //orthonormalize axes
        var invUpMag = 1.0 / Cartesian3.magnitudeSquared(up);
        var scalar = Cartesian3.dot(up, direction) * invUpMag;
        var w0 = Cartesian3.multiplyByScalar(direction, scalar, scratchCartesian$8);
        up = Cartesian3.normalize(
          Cartesian3.subtract(up, w0, camera._up),
          camera._up
        );
        Cartesian3.clone(up, camera.up);

        right = Cartesian3.cross(direction, up, camera._right);
        Cartesian3.clone(right, camera.right);
      }
    }

    if (directionChanged || transformChanged) {
      camera._directionWC = Matrix4.multiplyByPointAsVector(
        transform,
        direction,
        camera._directionWC
      );
      Cartesian3.normalize(camera._directionWC, camera._directionWC);
    }

    if (upChanged || transformChanged) {
      camera._upWC = Matrix4.multiplyByPointAsVector(transform, up, camera._upWC);
      Cartesian3.normalize(camera._upWC, camera._upWC);
    }

    if (rightChanged || transformChanged) {
      camera._rightWC = Matrix4.multiplyByPointAsVector(
        transform,
        right,
        camera._rightWC
      );
      Cartesian3.normalize(camera._rightWC, camera._rightWC);
    }

    if (
      positionChanged ||
      directionChanged ||
      upChanged ||
      rightChanged ||
      transformChanged
    ) {
      updateViewMatrix(camera);
    }
  }

  function getHeading(direction, up) {
    var heading;
    if (
      !CesiumMath.equalsEpsilon(Math.abs(direction.z), 1.0, CesiumMath.EPSILON3)
    ) {
      heading = Math.atan2(direction.y, direction.x) - CesiumMath.PI_OVER_TWO;
    } else {
      heading = Math.atan2(up.y, up.x) - CesiumMath.PI_OVER_TWO;
    }

    return CesiumMath.TWO_PI - CesiumMath.zeroToTwoPi(heading);
  }

  function getPitch(direction) {
    return CesiumMath.PI_OVER_TWO - CesiumMath.acosClamped(direction.z);
  }

  function getRoll(direction, up, right) {
    var roll = 0.0;
    if (
      !CesiumMath.equalsEpsilon(Math.abs(direction.z), 1.0, CesiumMath.EPSILON3)
    ) {
      roll = Math.atan2(-right.z, up.z);
      roll = CesiumMath.zeroToTwoPi(roll + CesiumMath.TWO_PI);
    }

    return roll;
  }

  var scratchHPRMatrix1 = new Matrix4();
  var scratchHPRMatrix2 = new Matrix4();

  Object.defineProperties(Camera.prototype, {
    /**
     * Gets the camera's reference frame. The inverse of this transformation is appended to the view matrix.
     * @memberof Camera.prototype
     *
     * @type {Matrix4}
     * @readonly
     *
     * @default {@link Matrix4.IDENTITY}
     */
    transform: {
      get: function () {
        return this._transform;
      },
    },

    /**
     * Gets the inverse camera transform.
     * @memberof Camera.prototype
     *
     * @type {Matrix4}
     * @readonly
     *
     * @default {@link Matrix4.IDENTITY}
     */
    inverseTransform: {
      get: function () {
        updateMembers(this);
        return this._invTransform;
      },
    },

    /**
     * Gets the view matrix.
     * @memberof Camera.prototype
     *
     * @type {Matrix4}
     * @readonly
     *
     * @see Camera#inverseViewMatrix
     */
    viewMatrix: {
      get: function () {
        updateMembers(this);
        return this._viewMatrix;
      },
    },

    /**
     * Gets the inverse view matrix.
     * @memberof Camera.prototype
     *
     * @type {Matrix4}
     * @readonly
     *
     * @see Camera#viewMatrix
     */
    inverseViewMatrix: {
      get: function () {
        updateMembers(this);
        return this._invViewMatrix;
      },
    },

    /**
     * Gets the {@link Cartographic} position of the camera, with longitude and latitude
     * expressed in radians and height in meters.  In 2D and Columbus View, it is possible
     * for the returned longitude and latitude to be outside the range of valid longitudes
     * and latitudes when the camera is outside the map.
     * @memberof Camera.prototype
     *
     * @type {Cartographic}
     * @readonly
     */
    positionCartographic: {
      get: function () {
        updateMembers(this);
        return this._positionCartographic;
      },
    },

    /**
     * Gets the position of the camera in world coordinates.
     * @memberof Camera.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    positionWC: {
      get: function () {
        updateMembers(this);
        return this._positionWC;
      },
    },

    /**
     * Gets the view direction of the camera in world coordinates.
     * @memberof Camera.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    directionWC: {
      get: function () {
        updateMembers(this);
        return this._directionWC;
      },
    },

    /**
     * Gets the up direction of the camera in world coordinates.
     * @memberof Camera.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    upWC: {
      get: function () {
        updateMembers(this);
        return this._upWC;
      },
    },

    /**
     * Gets the right direction of the camera in world coordinates.
     * @memberof Camera.prototype
     *
     * @type {Cartesian3}
     * @readonly
     */
    rightWC: {
      get: function () {
        updateMembers(this);
        return this._rightWC;
      },
    },

    /**
     * Gets the camera heading in radians.
     * @memberof Camera.prototype
     *
     * @type {Number}
     * @readonly
     */
    heading: {
      get: function () {
        if (this._mode !== SceneMode$1.MORPHING) {
          var ellipsoid = this._projection.ellipsoid;

          var oldTransform = Matrix4.clone(this._transform, scratchHPRMatrix1);
          var transform = Transforms.eastNorthUpToFixedFrame(
            this.positionWC,
            ellipsoid,
            scratchHPRMatrix2
          );
          this._setTransform(transform);

          var heading = getHeading(this.direction, this.up);

          this._setTransform(oldTransform);

          return heading;
        }

        return undefined;
      },
    },

    /**
     * Gets the camera pitch in radians.
     * @memberof Camera.prototype
     *
     * @type {Number}
     * @readonly
     */
    pitch: {
      get: function () {
        if (this._mode !== SceneMode$1.MORPHING) {
          var ellipsoid = this._projection.ellipsoid;

          var oldTransform = Matrix4.clone(this._transform, scratchHPRMatrix1);
          var transform = Transforms.eastNorthUpToFixedFrame(
            this.positionWC,
            ellipsoid,
            scratchHPRMatrix2
          );
          this._setTransform(transform);

          var pitch = getPitch(this.direction);

          this._setTransform(oldTransform);

          return pitch;
        }

        return undefined;
      },
    },

    /**
     * Gets the camera roll in radians.
     * @memberof Camera.prototype
     *
     * @type {Number}
     * @readonly
     */
    roll: {
      get: function () {
        if (this._mode !== SceneMode$1.MORPHING) {
          var ellipsoid = this._projection.ellipsoid;

          var oldTransform = Matrix4.clone(this._transform, scratchHPRMatrix1);
          var transform = Transforms.eastNorthUpToFixedFrame(
            this.positionWC,
            ellipsoid,
            scratchHPRMatrix2
          );
          this._setTransform(transform);

          var roll = getRoll(this.direction, this.up, this.right);

          this._setTransform(oldTransform);

          return roll;
        }

        return undefined;
      },
    },

    /**
     * Gets the event that will be raised at when the camera starts to move.
     * @memberof Camera.prototype
     * @type {Event}
     * @readonly
     */
    moveStart: {
      get: function () {
        return this._moveStart;
      },
    },

    /**
     * Gets the event that will be raised when the camera has stopped moving.
     * @memberof Camera.prototype
     * @type {Event}
     * @readonly
     */
    moveEnd: {
      get: function () {
        return this._moveEnd;
      },
    },

    /**
     * Gets the event that will be raised when the camera has changed by <code>percentageChanged</code>.
     * @memberof Camera.prototype
     * @type {Event}
     * @readonly
     */
    changed: {
      get: function () {
        return this._changed;
      },
    },
  });

  /**
   * @private
   */
  Camera.prototype.update = function (mode) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(mode)) {
      throw new DeveloperError("mode is required.");
    }
    if (
      mode === SceneMode$1.SCENE2D &&
      !(this.frustum instanceof OrthographicOffCenterFrustum)
    ) {
      throw new DeveloperError(
        "An OrthographicOffCenterFrustum is required in 2D."
      );
    }
    if (
      (mode === SceneMode$1.SCENE3D || mode === SceneMode$1.COLUMBUS_VIEW) &&
      !(this.frustum instanceof PerspectiveFrustum) &&
      !(this.frustum instanceof OrthographicFrustum)
    ) {
      throw new DeveloperError(
        "A PerspectiveFrustum or OrthographicFrustum is required in 3D and Columbus view"
      );
    }
    //>>includeEnd('debug');

    var updateFrustum = false;
    if (mode !== this._mode) {
      this._mode = mode;
      this._modeChanged = mode !== SceneMode$1.MORPHING;
      updateFrustum = this._mode === SceneMode$1.SCENE2D;
    }

    if (updateFrustum) {
      var frustum = (this._max2Dfrustum = this.frustum.clone());

      //>>includeStart('debug', pragmas.debug);
      if (!(frustum instanceof OrthographicOffCenterFrustum)) {
        throw new DeveloperError(
          "The camera frustum is expected to be orthographic for 2D camera control."
        );
      }
      //>>includeEnd('debug');

      var maxZoomOut = 2.0;
      var ratio = frustum.top / frustum.right;
      frustum.right = this._maxCoord.x * maxZoomOut;
      frustum.left = -frustum.right;
      frustum.top = ratio * frustum.right;
      frustum.bottom = -frustum.top;
    }

    if (this._mode === SceneMode$1.SCENE2D) {
      clampMove2D(this, this.position);
    }
  };

  var setTransformPosition = new Cartesian3();
  var setTransformUp = new Cartesian3();
  var setTransformDirection = new Cartesian3();

  Camera.prototype._setTransform = function (transform) {
    var position = Cartesian3.clone(this.positionWC, setTransformPosition);
    var up = Cartesian3.clone(this.upWC, setTransformUp);
    var direction = Cartesian3.clone(this.directionWC, setTransformDirection);

    Matrix4.clone(transform, this._transform);
    this._transformChanged = true;
    updateMembers(this);
    var inverse = this._actualInvTransform;

    Matrix4.multiplyByPoint(inverse, position, this.position);
    Matrix4.multiplyByPointAsVector(inverse, direction, this.direction);
    Matrix4.multiplyByPointAsVector(inverse, up, this.up);
    Cartesian3.cross(this.direction, this.up, this.right);

    updateMembers(this);
  };

  var scratchAdjustOrthographicFrustumMousePosition = new Cartesian2();
  var scratchPickRay = new Ray();
  var scratchRayIntersection = new Cartesian3();
  var scratchDepthIntersection = new Cartesian3();

  function calculateOrthographicFrustumWidth(camera) {
    // Camera is fixed to an object, so keep frustum width constant.
    if (!Matrix4.equals(Matrix4.IDENTITY, camera.transform)) {
      return Cartesian3.magnitude(camera.position);
    }

    var scene = camera._scene;
    var globe = scene.globe;

    var mousePosition = scratchAdjustOrthographicFrustumMousePosition;
    mousePosition.x = scene.drawingBufferWidth / 2.0;
    mousePosition.y = scene.drawingBufferHeight / 2.0;

    var rayIntersection;
    if (defined(globe)) {
      var ray = camera.getPickRay(mousePosition, scratchPickRay);
      rayIntersection = globe.pickWorldCoordinates(
        ray,
        scene,
        true,
        scratchRayIntersection
      );
    }

    var depthIntersection;
    if (scene.pickPositionSupported) {
      depthIntersection = scene.pickPositionWorldCoordinates(
        mousePosition,
        scratchDepthIntersection
      );
    }

    var distance;
    if (defined(rayIntersection) || defined(depthIntersection)) {
      var depthDistance = defined(depthIntersection)
        ? Cartesian3.distance(depthIntersection, camera.positionWC)
        : Number.POSITIVE_INFINITY;
      var rayDistance = defined(rayIntersection)
        ? Cartesian3.distance(rayIntersection, camera.positionWC)
        : Number.POSITIVE_INFINITY;
      distance = Math.min(depthDistance, rayDistance);
    } else {
      distance = Math.max(camera.positionCartographic.height, 0.0);
    }
    return distance;
  }

  Camera.prototype._adjustOrthographicFrustum = function (zooming) {
    if (!(this.frustum instanceof OrthographicFrustum)) {
      return;
    }

    if (!zooming && this._positionCartographic.height < 150000.0) {
      return;
    }

    this.frustum.width = calculateOrthographicFrustumWidth(this);
  };

  var scratchSetViewCartesian = new Cartesian3();
  var scratchSetViewTransform1 = new Matrix4();
  var scratchSetViewTransform2 = new Matrix4();
  var scratchSetViewQuaternion = new Quaternion();
  var scratchSetViewMatrix3 = new Matrix3();
  var scratchSetViewCartographic = new Cartographic();

  function setView3D(camera, position, hpr) {
    var currentTransform = Matrix4.clone(
      camera.transform,
      scratchSetViewTransform1
    );
    var localTransform = Transforms.eastNorthUpToFixedFrame(
      position,
      camera._projection.ellipsoid,
      scratchSetViewTransform2
    );
    camera._setTransform(localTransform);

    Cartesian3.clone(Cartesian3.ZERO, camera.position);
    hpr.heading = hpr.heading - CesiumMath.PI_OVER_TWO;

    var rotQuat = Quaternion.fromHeadingPitchRoll(hpr, scratchSetViewQuaternion);
    var rotMat = Matrix3.fromQuaternion(rotQuat, scratchSetViewMatrix3);

    Matrix3.getColumn(rotMat, 0, camera.direction);
    Matrix3.getColumn(rotMat, 2, camera.up);
    Cartesian3.cross(camera.direction, camera.up, camera.right);

    camera._setTransform(currentTransform);

    camera._adjustOrthographicFrustum(true);
  }

  function setViewCV(camera, position, hpr, convert) {
    var currentTransform = Matrix4.clone(
      camera.transform,
      scratchSetViewTransform1
    );
    camera._setTransform(Matrix4.IDENTITY);

    if (!Cartesian3.equals(position, camera.positionWC)) {
      if (convert) {
        var projection = camera._projection;
        var cartographic = projection.ellipsoid.cartesianToCartographic(
          position,
          scratchSetViewCartographic
        );
        position = projection.project(cartographic, scratchSetViewCartesian);
      }
      Cartesian3.clone(position, camera.position);
    }
    hpr.heading = hpr.heading - CesiumMath.PI_OVER_TWO;

    var rotQuat = Quaternion.fromHeadingPitchRoll(hpr, scratchSetViewQuaternion);
    var rotMat = Matrix3.fromQuaternion(rotQuat, scratchSetViewMatrix3);

    Matrix3.getColumn(rotMat, 0, camera.direction);
    Matrix3.getColumn(rotMat, 2, camera.up);
    Cartesian3.cross(camera.direction, camera.up, camera.right);

    camera._setTransform(currentTransform);

    camera._adjustOrthographicFrustum(true);
  }

  function setView2D(camera, position, hpr, convert) {
    var currentTransform = Matrix4.clone(
      camera.transform,
      scratchSetViewTransform1
    );
    camera._setTransform(Matrix4.IDENTITY);

    if (!Cartesian3.equals(position, camera.positionWC)) {
      if (convert) {
        var projection = camera._projection;
        var cartographic = projection.ellipsoid.cartesianToCartographic(
          position,
          scratchSetViewCartographic
        );
        position = projection.project(cartographic, scratchSetViewCartesian);
      }

      Cartesian2.clone(position, camera.position);

      var newLeft = -position.z * 0.5;
      var newRight = -newLeft;

      var frustum = camera.frustum;
      if (newRight > newLeft) {
        var ratio = frustum.top / frustum.right;
        frustum.right = newRight;
        frustum.left = newLeft;
        frustum.top = frustum.right * ratio;
        frustum.bottom = -frustum.top;
      }
    }

    if (camera._scene.mapMode2D === MapMode2D$1.ROTATE) {
      hpr.heading = hpr.heading - CesiumMath.PI_OVER_TWO;
      hpr.pitch = -CesiumMath.PI_OVER_TWO;
      hpr.roll = 0.0;
      var rotQuat = Quaternion.fromHeadingPitchRoll(
        hpr,
        scratchSetViewQuaternion
      );
      var rotMat = Matrix3.fromQuaternion(rotQuat, scratchSetViewMatrix3);

      Matrix3.getColumn(rotMat, 2, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
    }

    camera._setTransform(currentTransform);
  }

  var scratchToHPRDirection = new Cartesian3();
  var scratchToHPRUp = new Cartesian3();
  var scratchToHPRRight = new Cartesian3();

  function directionUpToHeadingPitchRoll(camera, position, orientation, result) {
    var direction = Cartesian3.clone(
      orientation.direction,
      scratchToHPRDirection
    );
    var up = Cartesian3.clone(orientation.up, scratchToHPRUp);

    if (camera._scene.mode === SceneMode$1.SCENE3D) {
      var ellipsoid = camera._projection.ellipsoid;
      var transform = Transforms.eastNorthUpToFixedFrame(
        position,
        ellipsoid,
        scratchHPRMatrix1
      );
      var invTransform = Matrix4.inverseTransformation(
        transform,
        scratchHPRMatrix2
      );

      Matrix4.multiplyByPointAsVector(invTransform, direction, direction);
      Matrix4.multiplyByPointAsVector(invTransform, up, up);
    }

    var right = Cartesian3.cross(direction, up, scratchToHPRRight);

    result.heading = getHeading(direction, up);
    result.pitch = getPitch(direction);
    result.roll = getRoll(direction, up, right);

    return result;
  }

  var scratchSetViewOptions = {
    destination: undefined,
    orientation: {
      direction: undefined,
      up: undefined,
      heading: undefined,
      pitch: undefined,
      roll: undefined,
    },
    convert: undefined,
    endTransform: undefined,
  };

  var scratchHpr = new HeadingPitchRoll();
  /**
   * Sets the camera position, orientation and transform.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3|Rectangle} [options.destination] The final position of the camera in WGS84 (world) coordinates or a rectangle that would be visible from a top-down view.
   * @param {Object} [options.orientation] An object that contains either direction and up properties or heading, pitch and roll properties. By default, the direction will point
   * towards the center of the frame in 3D and in the negative z direction in Columbus view. The up direction will point towards local north in 3D and in the positive
   * y direction in Columbus view. Orientation is not used in 2D when in infinite scrolling mode.
   * @param {Matrix4} [options.endTransform] Transform matrix representing the reference frame of the camera.
   * @param {Boolean} [options.convert] Whether to convert the destination from world coordinates to scene coordinates (only relevant when not using 3D). Defaults to <code>true</code>.
   *
   * @example
   * // 1. Set position with a top-down view
   * viewer.camera.setView({
   *     destination : Cesium.Cartesian3.fromDegrees(-117.16, 32.71, 15000.0)
   * });
   *
   * // 2 Set view with heading, pitch and roll
   * viewer.camera.setView({
   *     destination : cartesianPosition,
   *     orientation: {
   *         heading : Cesium.Math.toRadians(90.0), // east, default value is 0.0 (north)
   *         pitch : Cesium.Math.toRadians(-90),    // default value (looking down)
   *         roll : 0.0                             // default value
   *     }
   * });
   *
   * // 3. Change heading, pitch and roll with the camera position remaining the same.
   * viewer.camera.setView({
   *     orientation: {
   *         heading : Cesium.Math.toRadians(90.0), // east, default value is 0.0 (north)
   *         pitch : Cesium.Math.toRadians(-90),    // default value (looking down)
   *         roll : 0.0                             // default value
   *     }
   * });
   *
   *
   * // 4. View rectangle with a top-down view
   * viewer.camera.setView({
   *     destination : Cesium.Rectangle.fromDegrees(west, south, east, north)
   * });
   *
   * // 5. Set position with an orientation using unit vectors.
   * viewer.camera.setView({
   *     destination : Cesium.Cartesian3.fromDegrees(-122.19, 46.25, 5000.0),
   *     orientation : {
   *         direction : new Cesium.Cartesian3(-0.04231243104240401, -0.20123236049443421, -0.97862924300734),
   *         up : new Cesium.Cartesian3(-0.47934589305293746, -0.8553216253114552, 0.1966022179118339)
   *     }
   * });
   */
  Camera.prototype.setView = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var orientation = defaultValue(
      options.orientation,
      defaultValue.EMPTY_OBJECT
    );

    var mode = this._mode;
    if (mode === SceneMode$1.MORPHING) {
      return;
    }

    if (defined(options.endTransform)) {
      this._setTransform(options.endTransform);
    }

    var convert = defaultValue(options.convert, true);
    var destination = defaultValue(
      options.destination,
      Cartesian3.clone(this.positionWC, scratchSetViewCartesian)
    );
    if (defined(destination) && defined(destination.west)) {
      destination = this.getRectangleCameraCoordinates(
        destination,
        scratchSetViewCartesian
      );
      convert = false;
    }

    if (defined(orientation.direction)) {
      orientation = directionUpToHeadingPitchRoll(
        this,
        destination,
        orientation,
        scratchSetViewOptions.orientation
      );
    }

    scratchHpr.heading = defaultValue(orientation.heading, 0.0);
    scratchHpr.pitch = defaultValue(orientation.pitch, -CesiumMath.PI_OVER_TWO);
    scratchHpr.roll = defaultValue(orientation.roll, 0.0);

    if (mode === SceneMode$1.SCENE3D) {
      setView3D(this, destination, scratchHpr);
    } else if (mode === SceneMode$1.SCENE2D) {
      setView2D(this, destination, scratchHpr, convert);
    } else {
      setViewCV(this, destination, scratchHpr, convert);
    }
  };

  var pitchScratch = new Cartesian3();
  /**
   * Fly the camera to the home view.  Use {@link Camera#.DEFAULT_VIEW_RECTANGLE} to set
   * the default view for the 3D scene.  The home view for 2D and columbus view shows the
   * entire map.
   *
   * @param {Number} [duration] The duration of the flight in seconds. If omitted, Cesium attempts to calculate an ideal duration based on the distance to be traveled by the flight. See {@link Camera#flyTo}
   */
  Camera.prototype.flyHome = function (duration) {
    var mode = this._mode;

    if (mode === SceneMode$1.MORPHING) {
      this._scene.completeMorph();
    }

    if (mode === SceneMode$1.SCENE2D) {
      this.flyTo({
        destination: Camera.DEFAULT_VIEW_RECTANGLE,
        duration: duration,
        endTransform: Matrix4.IDENTITY,
      });
    } else if (mode === SceneMode$1.SCENE3D) {
      var destination = this.getRectangleCameraCoordinates(
        Camera.DEFAULT_VIEW_RECTANGLE
      );

      var mag = Cartesian3.magnitude(destination);
      mag += mag * Camera.DEFAULT_VIEW_FACTOR;
      Cartesian3.normalize(destination, destination);
      Cartesian3.multiplyByScalar(destination, mag, destination);

      this.flyTo({
        destination: destination,
        duration: duration,
        endTransform: Matrix4.IDENTITY,
      });
    } else if (mode === SceneMode$1.COLUMBUS_VIEW) {
      var maxRadii = this._projection.ellipsoid.maximumRadius;
      var position = new Cartesian3(0.0, -1.0, 1.0);
      position = Cartesian3.multiplyByScalar(
        Cartesian3.normalize(position, position),
        5.0 * maxRadii,
        position
      );
      this.flyTo({
        destination: position,
        duration: duration,
        orientation: {
          heading: 0.0,
          pitch: -Math.acos(Cartesian3.normalize(position, pitchScratch).z),
          roll: 0.0,
        },
        endTransform: Matrix4.IDENTITY,
        convert: false,
      });
    }
  };

  /**
   * Transform a vector or point from world coordinates to the camera's reference frame.
   *
   * @param {Cartesian4} cartesian The vector or point to transform.
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4} The transformed vector or point.
   */
  Camera.prototype.worldToCameraCoordinates = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian4();
    }
    updateMembers(this);
    return Matrix4.multiplyByVector(this._actualInvTransform, cartesian, result);
  };

  /**
   * Transform a point from world coordinates to the camera's reference frame.
   *
   * @param {Cartesian3} cartesian The point to transform.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The transformed point.
   */
  Camera.prototype.worldToCameraCoordinatesPoint = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }
    updateMembers(this);
    return Matrix4.multiplyByPoint(this._actualInvTransform, cartesian, result);
  };

  /**
   * Transform a vector from world coordinates to the camera's reference frame.
   *
   * @param {Cartesian3} cartesian The vector to transform.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The transformed vector.
   */
  Camera.prototype.worldToCameraCoordinatesVector = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }
    updateMembers(this);
    return Matrix4.multiplyByPointAsVector(
      this._actualInvTransform,
      cartesian,
      result
    );
  };

  /**
   * Transform a vector or point from the camera's reference frame to world coordinates.
   *
   * @param {Cartesian4} cartesian The vector or point to transform.
   * @param {Cartesian4} [result] The object onto which to store the result.
   * @returns {Cartesian4} The transformed vector or point.
   */
  Camera.prototype.cameraToWorldCoordinates = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian4();
    }
    updateMembers(this);
    return Matrix4.multiplyByVector(this._actualTransform, cartesian, result);
  };

  /**
   * Transform a point from the camera's reference frame to world coordinates.
   *
   * @param {Cartesian3} cartesian The point to transform.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The transformed point.
   */
  Camera.prototype.cameraToWorldCoordinatesPoint = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }
    updateMembers(this);
    return Matrix4.multiplyByPoint(this._actualTransform, cartesian, result);
  };

  /**
   * Transform a vector from the camera's reference frame to world coordinates.
   *
   * @param {Cartesian3} cartesian The vector to transform.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3} The transformed vector.
   */
  Camera.prototype.cameraToWorldCoordinatesVector = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartesian)) {
      throw new DeveloperError("cartesian is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Cartesian3();
    }
    updateMembers(this);
    return Matrix4.multiplyByPointAsVector(
      this._actualTransform,
      cartesian,
      result
    );
  };

  function clampMove2D(camera, position) {
    var rotatable2D = camera._scene.mapMode2D === MapMode2D$1.ROTATE;
    var maxProjectedX = camera._maxCoord.x;
    var maxProjectedY = camera._maxCoord.y;

    var minX;
    var maxX;
    if (rotatable2D) {
      maxX = maxProjectedX;
      minX = -maxX;
    } else {
      maxX = position.x - maxProjectedX * 2.0;
      minX = position.x + maxProjectedX * 2.0;
    }

    if (position.x > maxProjectedX) {
      position.x = maxX;
    }
    if (position.x < -maxProjectedX) {
      position.x = minX;
    }

    if (position.y > maxProjectedY) {
      position.y = maxProjectedY;
    }
    if (position.y < -maxProjectedY) {
      position.y = -maxProjectedY;
    }
  }

  var moveScratch = new Cartesian3();
  /**
   * Translates the camera's position by <code>amount</code> along <code>direction</code>.
   *
   * @param {Cartesian3} direction The direction to move.
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveBackward
   * @see Camera#moveForward
   * @see Camera#moveLeft
   * @see Camera#moveRight
   * @see Camera#moveUp
   * @see Camera#moveDown
   */
  Camera.prototype.move = function (direction, amount) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(direction)) {
      throw new DeveloperError("direction is required.");
    }
    //>>includeEnd('debug');

    var cameraPosition = this.position;
    Cartesian3.multiplyByScalar(direction, amount, moveScratch);
    Cartesian3.add(cameraPosition, moveScratch, cameraPosition);

    if (this._mode === SceneMode$1.SCENE2D) {
      clampMove2D(this, cameraPosition);
    }
    this._adjustOrthographicFrustum(true);
  };

  /**
   * Translates the camera's position by <code>amount</code> along the camera's view vector.
   * When in 2D mode, this will zoom in the camera instead of translating the camera's position.
   *
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveBackward
   */
  Camera.prototype.moveForward = function (amount) {
    amount = defaultValue(amount, this.defaultMoveAmount);

    if (this._mode === SceneMode$1.SCENE2D) {
      // 2D mode
      zoom2D(this, amount);
    } else {
      // 3D or Columbus view mode
      this.move(this.direction, amount);
    }
  };

  /**
   * Translates the camera's position by <code>amount</code> along the opposite direction
   * of the camera's view vector.
   * When in 2D mode, this will zoom out the camera instead of translating the camera's position.
   *
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveForward
   */
  Camera.prototype.moveBackward = function (amount) {
    amount = defaultValue(amount, this.defaultMoveAmount);

    if (this._mode === SceneMode$1.SCENE2D) {
      // 2D mode
      zoom2D(this, -amount);
    } else {
      // 3D or Columbus view mode
      this.move(this.direction, -amount);
    }
  };

  /**
   * Translates the camera's position by <code>amount</code> along the camera's up vector.
   *
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveDown
   */
  Camera.prototype.moveUp = function (amount) {
    amount = defaultValue(amount, this.defaultMoveAmount);
    this.move(this.up, amount);
  };

  /**
   * Translates the camera's position by <code>amount</code> along the opposite direction
   * of the camera's up vector.
   *
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveUp
   */
  Camera.prototype.moveDown = function (amount) {
    amount = defaultValue(amount, this.defaultMoveAmount);
    this.move(this.up, -amount);
  };

  /**
   * Translates the camera's position by <code>amount</code> along the camera's right vector.
   *
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveLeft
   */
  Camera.prototype.moveRight = function (amount) {
    amount = defaultValue(amount, this.defaultMoveAmount);
    this.move(this.right, amount);
  };

  /**
   * Translates the camera's position by <code>amount</code> along the opposite direction
   * of the camera's right vector.
   *
   * @param {Number} [amount] The amount, in meters, to move. Defaults to <code>defaultMoveAmount</code>.
   *
   * @see Camera#moveRight
   */
  Camera.prototype.moveLeft = function (amount) {
    amount = defaultValue(amount, this.defaultMoveAmount);
    this.move(this.right, -amount);
  };

  /**
   * Rotates the camera around its up vector by amount, in radians, in the opposite direction
   * of its right vector if not in 2D mode.
   *
   * @param {Number} [amount] The amount, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#lookRight
   */
  Camera.prototype.lookLeft = function (amount) {
    amount = defaultValue(amount, this.defaultLookAmount);

    // only want view of map to change in 3D mode, 2D visual is incorrect when look changes
    if (this._mode !== SceneMode$1.SCENE2D) {
      this.look(this.up, -amount);
    }
  };

  /**
   * Rotates the camera around its up vector by amount, in radians, in the direction
   * of its right vector if not in 2D mode.
   *
   * @param {Number} [amount] The amount, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#lookLeft
   */
  Camera.prototype.lookRight = function (amount) {
    amount = defaultValue(amount, this.defaultLookAmount);

    // only want view of map to change in 3D mode, 2D visual is incorrect when look changes
    if (this._mode !== SceneMode$1.SCENE2D) {
      this.look(this.up, amount);
    }
  };

  /**
   * Rotates the camera around its right vector by amount, in radians, in the direction
   * of its up vector if not in 2D mode.
   *
   * @param {Number} [amount] The amount, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#lookDown
   */
  Camera.prototype.lookUp = function (amount) {
    amount = defaultValue(amount, this.defaultLookAmount);

    // only want view of map to change in 3D mode, 2D visual is incorrect when look changes
    if (this._mode !== SceneMode$1.SCENE2D) {
      this.look(this.right, -amount);
    }
  };

  /**
   * Rotates the camera around its right vector by amount, in radians, in the opposite direction
   * of its up vector if not in 2D mode.
   *
   * @param {Number} [amount] The amount, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#lookUp
   */
  Camera.prototype.lookDown = function (amount) {
    amount = defaultValue(amount, this.defaultLookAmount);

    // only want view of map to change in 3D mode, 2D visual is incorrect when look changes
    if (this._mode !== SceneMode$1.SCENE2D) {
      this.look(this.right, amount);
    }
  };

  var lookScratchQuaternion = new Quaternion();
  var lookScratchMatrix = new Matrix3();
  /**
   * Rotate each of the camera's orientation vectors around <code>axis</code> by <code>angle</code>
   *
   * @param {Cartesian3} axis The axis to rotate around.
   * @param {Number} [angle] The angle, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#lookUp
   * @see Camera#lookDown
   * @see Camera#lookLeft
   * @see Camera#lookRight
   */
  Camera.prototype.look = function (axis, angle) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(axis)) {
      throw new DeveloperError("axis is required.");
    }
    //>>includeEnd('debug');

    var turnAngle = defaultValue(angle, this.defaultLookAmount);
    var quaternion = Quaternion.fromAxisAngle(
      axis,
      -turnAngle,
      lookScratchQuaternion
    );
    var rotation = Matrix3.fromQuaternion(quaternion, lookScratchMatrix);

    var direction = this.direction;
    var up = this.up;
    var right = this.right;

    Matrix3.multiplyByVector(rotation, direction, direction);
    Matrix3.multiplyByVector(rotation, up, up);
    Matrix3.multiplyByVector(rotation, right, right);
  };

  /**
   * Rotate the camera counter-clockwise around its direction vector by amount, in radians.
   *
   * @param {Number} [amount] The amount, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#twistRight
   */
  Camera.prototype.twistLeft = function (amount) {
    amount = defaultValue(amount, this.defaultLookAmount);
    this.look(this.direction, amount);
  };

  /**
   * Rotate the camera clockwise around its direction vector by amount, in radians.
   *
   * @param {Number} [amount] The amount, in radians, to rotate by. Defaults to <code>defaultLookAmount</code>.
   *
   * @see Camera#twistLeft
   */
  Camera.prototype.twistRight = function (amount) {
    amount = defaultValue(amount, this.defaultLookAmount);
    this.look(this.direction, -amount);
  };

  var rotateScratchQuaternion = new Quaternion();
  var rotateScratchMatrix = new Matrix3();
  /**
   * Rotates the camera around <code>axis</code> by <code>angle</code>. The distance
   * of the camera's position to the center of the camera's reference frame remains the same.
   *
   * @param {Cartesian3} axis The axis to rotate around given in world coordinates.
   * @param {Number} [angle] The angle, in radians, to rotate by. Defaults to <code>defaultRotateAmount</code>.
   *
   * @see Camera#rotateUp
   * @see Camera#rotateDown
   * @see Camera#rotateLeft
   * @see Camera#rotateRight
   */
  Camera.prototype.rotate = function (axis, angle) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(axis)) {
      throw new DeveloperError("axis is required.");
    }
    //>>includeEnd('debug');

    var turnAngle = defaultValue(angle, this.defaultRotateAmount);
    var quaternion = Quaternion.fromAxisAngle(
      axis,
      -turnAngle,
      rotateScratchQuaternion
    );
    var rotation = Matrix3.fromQuaternion(quaternion, rotateScratchMatrix);
    Matrix3.multiplyByVector(rotation, this.position, this.position);
    Matrix3.multiplyByVector(rotation, this.direction, this.direction);
    Matrix3.multiplyByVector(rotation, this.up, this.up);
    Cartesian3.cross(this.direction, this.up, this.right);
    Cartesian3.cross(this.right, this.direction, this.up);

    this._adjustOrthographicFrustum(false);
  };

  /**
   * Rotates the camera around the center of the camera's reference frame by angle downwards.
   *
   * @param {Number} [angle] The angle, in radians, to rotate by. Defaults to <code>defaultRotateAmount</code>.
   *
   * @see Camera#rotateUp
   * @see Camera#rotate
   */
  Camera.prototype.rotateDown = function (angle) {
    angle = defaultValue(angle, this.defaultRotateAmount);
    rotateVertical(this, angle);
  };

  /**
   * Rotates the camera around the center of the camera's reference frame by angle upwards.
   *
   * @param {Number} [angle] The angle, in radians, to rotate by. Defaults to <code>defaultRotateAmount</code>.
   *
   * @see Camera#rotateDown
   * @see Camera#rotate
   */
  Camera.prototype.rotateUp = function (angle) {
    angle = defaultValue(angle, this.defaultRotateAmount);
    rotateVertical(this, -angle);
  };

  var rotateVertScratchP = new Cartesian3();
  var rotateVertScratchA = new Cartesian3();
  var rotateVertScratchTan = new Cartesian3();
  var rotateVertScratchNegate = new Cartesian3();
  function rotateVertical(camera, angle) {
    var position = camera.position;
    if (
      defined(camera.constrainedAxis) &&
      !Cartesian3.equalsEpsilon(
        camera.position,
        Cartesian3.ZERO,
        CesiumMath.EPSILON2
      )
    ) {
      var p = Cartesian3.normalize(position, rotateVertScratchP);
      var northParallel = Cartesian3.equalsEpsilon(
        p,
        camera.constrainedAxis,
        CesiumMath.EPSILON2
      );
      var southParallel = Cartesian3.equalsEpsilon(
        p,
        Cartesian3.negate(camera.constrainedAxis, rotateVertScratchNegate),
        CesiumMath.EPSILON2
      );
      if (!northParallel && !southParallel) {
        var constrainedAxis = Cartesian3.normalize(
          camera.constrainedAxis,
          rotateVertScratchA
        );

        var dot = Cartesian3.dot(p, constrainedAxis);
        var angleToAxis = CesiumMath.acosClamped(dot);
        if (angle > 0 && angle > angleToAxis) {
          angle = angleToAxis - CesiumMath.EPSILON4;
        }

        dot = Cartesian3.dot(
          p,
          Cartesian3.negate(constrainedAxis, rotateVertScratchNegate)
        );
        angleToAxis = CesiumMath.acosClamped(dot);
        if (angle < 0 && -angle > angleToAxis) {
          angle = -angleToAxis + CesiumMath.EPSILON4;
        }

        var tangent = Cartesian3.cross(constrainedAxis, p, rotateVertScratchTan);
        camera.rotate(tangent, angle);
      } else if ((northParallel && angle < 0) || (southParallel && angle > 0)) {
        camera.rotate(camera.right, angle);
      }
    } else {
      camera.rotate(camera.right, angle);
    }
  }

  /**
   * Rotates the camera around the center of the camera's reference frame by angle to the right.
   *
   * @param {Number} [angle] The angle, in radians, to rotate by. Defaults to <code>defaultRotateAmount</code>.
   *
   * @see Camera#rotateLeft
   * @see Camera#rotate
   */
  Camera.prototype.rotateRight = function (angle) {
    angle = defaultValue(angle, this.defaultRotateAmount);
    rotateHorizontal(this, -angle);
  };

  /**
   * Rotates the camera around the center of the camera's reference frame by angle to the left.
   *
   * @param {Number} [angle] The angle, in radians, to rotate by. Defaults to <code>defaultRotateAmount</code>.
   *
   * @see Camera#rotateRight
   * @see Camera#rotate
   */
  Camera.prototype.rotateLeft = function (angle) {
    angle = defaultValue(angle, this.defaultRotateAmount);
    rotateHorizontal(this, angle);
  };

  function rotateHorizontal(camera, angle) {
    if (defined(camera.constrainedAxis)) {
      camera.rotate(camera.constrainedAxis, angle);
    } else {
      camera.rotate(camera.up, angle);
    }
  }

  function zoom2D(camera, amount) {
    var frustum = camera.frustum;

    //>>includeStart('debug', pragmas.debug);
    if (
      !(frustum instanceof OrthographicOffCenterFrustum) ||
      !defined(frustum.left) ||
      !defined(frustum.right) ||
      !defined(frustum.bottom) ||
      !defined(frustum.top)
    ) {
      throw new DeveloperError(
        "The camera frustum is expected to be orthographic for 2D camera control."
      );
    }
    //>>includeEnd('debug');

    var ratio;
    amount = amount * 0.5;

    if (
      Math.abs(frustum.top) + Math.abs(frustum.bottom) >
      Math.abs(frustum.left) + Math.abs(frustum.right)
    ) {
      var newTop = frustum.top - amount;
      var newBottom = frustum.bottom + amount;

      var maxBottom = camera._maxCoord.y;
      if (camera._scene.mapMode2D === MapMode2D$1.ROTATE) {
        maxBottom *= camera.maximumZoomFactor;
      }

      if (newBottom > maxBottom) {
        newBottom = maxBottom;
        newTop = -maxBottom;
      }

      if (newTop <= newBottom) {
        newTop = 1.0;
        newBottom = -1.0;
      }

      ratio = frustum.right / frustum.top;
      frustum.top = newTop;
      frustum.bottom = newBottom;
      frustum.right = frustum.top * ratio;
      frustum.left = -frustum.right;
    } else {
      var newRight = frustum.right - amount;
      var newLeft = frustum.left + amount;

      var maxRight = camera._maxCoord.x;
      if (camera._scene.mapMode2D === MapMode2D$1.ROTATE) {
        maxRight *= camera.maximumZoomFactor;
      }

      if (newRight > maxRight) {
        newRight = maxRight;
        newLeft = -maxRight;
      }

      if (newRight <= newLeft) {
        newRight = 1.0;
        newLeft = -1.0;
      }
      ratio = frustum.top / frustum.right;
      frustum.right = newRight;
      frustum.left = newLeft;
      frustum.top = frustum.right * ratio;
      frustum.bottom = -frustum.top;
    }
  }

  function zoom3D(camera, amount) {
    camera.move(camera.direction, amount);
  }

  /**
   * Zooms <code>amount</code> along the camera's view vector.
   *
   * @param {Number} [amount] The amount to move. Defaults to <code>defaultZoomAmount</code>.
   *
   * @see Camera#zoomOut
   */
  Camera.prototype.zoomIn = function (amount) {
    amount = defaultValue(amount, this.defaultZoomAmount);
    if (this._mode === SceneMode$1.SCENE2D) {
      zoom2D(this, amount);
    } else {
      zoom3D(this, amount);
    }
  };

  /**
   * Zooms <code>amount</code> along the opposite direction of
   * the camera's view vector.
   *
   * @param {Number} [amount] The amount to move. Defaults to <code>defaultZoomAmount</code>.
   *
   * @see Camera#zoomIn
   */
  Camera.prototype.zoomOut = function (amount) {
    amount = defaultValue(amount, this.defaultZoomAmount);
    if (this._mode === SceneMode$1.SCENE2D) {
      zoom2D(this, -amount);
    } else {
      zoom3D(this, -amount);
    }
  };

  /**
   * Gets the magnitude of the camera position. In 3D, this is the vector magnitude. In 2D and
   * Columbus view, this is the distance to the map.
   *
   * @returns {Number} The magnitude of the position.
   */
  Camera.prototype.getMagnitude = function () {
    if (this._mode === SceneMode$1.SCENE3D) {
      return Cartesian3.magnitude(this.position);
    } else if (this._mode === SceneMode$1.COLUMBUS_VIEW) {
      return Math.abs(this.position.z);
    } else if (this._mode === SceneMode$1.SCENE2D) {
      return Math.max(
        this.frustum.right - this.frustum.left,
        this.frustum.top - this.frustum.bottom
      );
    }
  };

  var scratchLookAtMatrix4 = new Matrix4();

  /**
   * Sets the camera position and orientation using a target and offset. The target must be given in
   * world coordinates. The offset can be either a cartesian or heading/pitch/range in the local east-north-up reference frame centered at the target.
   * If the offset is a cartesian, then it is an offset from the center of the reference frame defined by the transformation matrix. If the offset
   * is heading/pitch/range, then the heading and the pitch angles are defined in the reference frame defined by the transformation matrix.
   * The heading is the angle from y axis and increasing towards the x axis. Pitch is the rotation from the xy-plane. Positive pitch
   * angles are below the plane. Negative pitch angles are above the plane. The range is the distance from the center.
   *
   * In 2D, there must be a top down view. The camera will be placed above the target looking down. The height above the
   * target will be the magnitude of the offset. The heading will be determined from the offset. If the heading cannot be
   * determined from the offset, the heading will be north.
   *
   * @param {Cartesian3} target The target position in world coordinates.
   * @param {Cartesian3|HeadingPitchRange} offset The offset from the target in the local east-north-up reference frame centered at the target.
   *
   * @exception {DeveloperError} lookAt is not supported while morphing.
   *
   * @example
   * // 1. Using a cartesian offset
   * var center = Cesium.Cartesian3.fromDegrees(-98.0, 40.0);
   * viewer.camera.lookAt(center, new Cesium.Cartesian3(0.0, -4790000.0, 3930000.0));
   *
   * // 2. Using a HeadingPitchRange offset
   * var center = Cesium.Cartesian3.fromDegrees(-72.0, 40.0);
   * var heading = Cesium.Math.toRadians(50.0);
   * var pitch = Cesium.Math.toRadians(-20.0);
   * var range = 5000.0;
   * viewer.camera.lookAt(center, new Cesium.HeadingPitchRange(heading, pitch, range));
   */
  Camera.prototype.lookAt = function (target, offset) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(target)) {
      throw new DeveloperError("target is required");
    }
    if (!defined(offset)) {
      throw new DeveloperError("offset is required");
    }
    if (this._mode === SceneMode$1.MORPHING) {
      throw new DeveloperError("lookAt is not supported while morphing.");
    }
    //>>includeEnd('debug');

    var transform = Transforms.eastNorthUpToFixedFrame(
      target,
      Ellipsoid.WGS84,
      scratchLookAtMatrix4
    );
    this.lookAtTransform(transform, offset);
  };

  var scratchLookAtHeadingPitchRangeOffset = new Cartesian3();
  var scratchLookAtHeadingPitchRangeQuaternion1 = new Quaternion();
  var scratchLookAtHeadingPitchRangeQuaternion2 = new Quaternion();
  var scratchHeadingPitchRangeMatrix3 = new Matrix3();

  function offsetFromHeadingPitchRange(heading, pitch, range) {
    pitch = CesiumMath.clamp(
      pitch,
      -CesiumMath.PI_OVER_TWO,
      CesiumMath.PI_OVER_TWO
    );
    heading = CesiumMath.zeroToTwoPi(heading) - CesiumMath.PI_OVER_TWO;

    var pitchQuat = Quaternion.fromAxisAngle(
      Cartesian3.UNIT_Y,
      -pitch,
      scratchLookAtHeadingPitchRangeQuaternion1
    );
    var headingQuat = Quaternion.fromAxisAngle(
      Cartesian3.UNIT_Z,
      -heading,
      scratchLookAtHeadingPitchRangeQuaternion2
    );
    var rotQuat = Quaternion.multiply(headingQuat, pitchQuat, headingQuat);
    var rotMatrix = Matrix3.fromQuaternion(
      rotQuat,
      scratchHeadingPitchRangeMatrix3
    );

    var offset = Cartesian3.clone(
      Cartesian3.UNIT_X,
      scratchLookAtHeadingPitchRangeOffset
    );
    Matrix3.multiplyByVector(rotMatrix, offset, offset);
    Cartesian3.negate(offset, offset);
    Cartesian3.multiplyByScalar(offset, range, offset);
    return offset;
  }

  /**
   * Sets the camera position and orientation using a target and transformation matrix. The offset can be either a cartesian or heading/pitch/range.
   * If the offset is a cartesian, then it is an offset from the center of the reference frame defined by the transformation matrix. If the offset
   * is heading/pitch/range, then the heading and the pitch angles are defined in the reference frame defined by the transformation matrix.
   * The heading is the angle from y axis and increasing towards the x axis. Pitch is the rotation from the xy-plane. Positive pitch
   * angles are below the plane. Negative pitch angles are above the plane. The range is the distance from the center.
   *
   * In 2D, there must be a top down view. The camera will be placed above the center of the reference frame. The height above the
   * target will be the magnitude of the offset. The heading will be determined from the offset. If the heading cannot be
   * determined from the offset, the heading will be north.
   *
   * @param {Matrix4} transform The transformation matrix defining the reference frame.
   * @param {Cartesian3|HeadingPitchRange} [offset] The offset from the target in a reference frame centered at the target.
   *
   * @exception {DeveloperError} lookAtTransform is not supported while morphing.
   *
   * @example
   * // 1. Using a cartesian offset
   * var transform = Cesium.Transforms.eastNorthUpToFixedFrame(Cesium.Cartesian3.fromDegrees(-98.0, 40.0));
   * viewer.camera.lookAtTransform(transform, new Cesium.Cartesian3(0.0, -4790000.0, 3930000.0));
   *
   * // 2. Using a HeadingPitchRange offset
   * var transform = Cesium.Transforms.eastNorthUpToFixedFrame(Cesium.Cartesian3.fromDegrees(-72.0, 40.0));
   * var heading = Cesium.Math.toRadians(50.0);
   * var pitch = Cesium.Math.toRadians(-20.0);
   * var range = 5000.0;
   * viewer.camera.lookAtTransform(transform, new Cesium.HeadingPitchRange(heading, pitch, range));
   */
  Camera.prototype.lookAtTransform = function (transform, offset) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(transform)) {
      throw new DeveloperError("transform is required");
    }
    if (this._mode === SceneMode$1.MORPHING) {
      throw new DeveloperError(
        "lookAtTransform is not supported while morphing."
      );
    }
    //>>includeEnd('debug');

    this._setTransform(transform);
    if (!defined(offset)) {
      return;
    }

    var cartesianOffset;
    if (defined(offset.heading)) {
      cartesianOffset = offsetFromHeadingPitchRange(
        offset.heading,
        offset.pitch,
        offset.range
      );
    } else {
      cartesianOffset = offset;
    }

    if (this._mode === SceneMode$1.SCENE2D) {
      Cartesian2.clone(Cartesian2.ZERO, this.position);

      Cartesian3.negate(cartesianOffset, this.up);
      this.up.z = 0.0;

      if (Cartesian3.magnitudeSquared(this.up) < CesiumMath.EPSILON10) {
        Cartesian3.clone(Cartesian3.UNIT_Y, this.up);
      }

      Cartesian3.normalize(this.up, this.up);

      this._setTransform(Matrix4.IDENTITY);

      Cartesian3.negate(Cartesian3.UNIT_Z, this.direction);
      Cartesian3.cross(this.direction, this.up, this.right);
      Cartesian3.normalize(this.right, this.right);

      var frustum = this.frustum;
      var ratio = frustum.top / frustum.right;
      frustum.right = Cartesian3.magnitude(cartesianOffset) * 0.5;
      frustum.left = -frustum.right;
      frustum.top = ratio * frustum.right;
      frustum.bottom = -frustum.top;

      this._setTransform(transform);

      return;
    }

    Cartesian3.clone(cartesianOffset, this.position);
    Cartesian3.negate(this.position, this.direction);
    Cartesian3.normalize(this.direction, this.direction);
    Cartesian3.cross(this.direction, Cartesian3.UNIT_Z, this.right);

    if (Cartesian3.magnitudeSquared(this.right) < CesiumMath.EPSILON10) {
      Cartesian3.clone(Cartesian3.UNIT_X, this.right);
    }

    Cartesian3.normalize(this.right, this.right);
    Cartesian3.cross(this.right, this.direction, this.up);
    Cartesian3.normalize(this.up, this.up);

    this._adjustOrthographicFrustum(true);
  };

  var viewRectangle3DCartographic1 = new Cartographic();
  var viewRectangle3DCartographic2 = new Cartographic();
  var viewRectangle3DNorthEast = new Cartesian3();
  var viewRectangle3DSouthWest = new Cartesian3();
  var viewRectangle3DNorthWest = new Cartesian3();
  var viewRectangle3DSouthEast = new Cartesian3();
  var viewRectangle3DNorthCenter = new Cartesian3();
  var viewRectangle3DSouthCenter = new Cartesian3();
  var viewRectangle3DCenter = new Cartesian3();
  var viewRectangle3DEquator = new Cartesian3();
  var defaultRF = {
    direction: new Cartesian3(),
    right: new Cartesian3(),
    up: new Cartesian3(),
  };
  var viewRectangle3DEllipsoidGeodesic;

  function computeD(direction, upOrRight, corner, tanThetaOrPhi) {
    var opposite = Math.abs(Cartesian3.dot(upOrRight, corner));
    return opposite / tanThetaOrPhi - Cartesian3.dot(direction, corner);
  }

  function rectangleCameraPosition3D(camera, rectangle, result, updateCamera) {
    var ellipsoid = camera._projection.ellipsoid;
    var cameraRF = updateCamera ? camera : defaultRF;

    var north = rectangle.north;
    var south = rectangle.south;
    var east = rectangle.east;
    var west = rectangle.west;

    // If we go across the International Date Line
    if (west > east) {
      east += CesiumMath.TWO_PI;
    }

    // Find the midpoint latitude.
    //
    // EllipsoidGeodesic will fail if the north and south edges are very close to being on opposite sides of the ellipsoid.
    // Ideally we'd just call EllipsoidGeodesic.setEndPoints and let it throw when it detects this case, but sadly it doesn't
    // even look for this case in optimized builds, so we have to test for it here instead.
    //
    // Fortunately, this case can only happen (here) when north is very close to the north pole and south is very close to the south pole,
    // so handle it just by using 0 latitude as the center.  It's certainliy possible to use a smaller tolerance
    // than one degree here, but one degree is safe and putting the center at 0 latitude should be good enough for any
    // rectangle that spans 178+ of the 180 degrees of latitude.
    var longitude = (west + east) * 0.5;
    var latitude;
    if (
      south < -CesiumMath.PI_OVER_TWO + CesiumMath.RADIANS_PER_DEGREE &&
      north > CesiumMath.PI_OVER_TWO - CesiumMath.RADIANS_PER_DEGREE
    ) {
      latitude = 0.0;
    } else {
      var northCartographic = viewRectangle3DCartographic1;
      northCartographic.longitude = longitude;
      northCartographic.latitude = north;
      northCartographic.height = 0.0;

      var southCartographic = viewRectangle3DCartographic2;
      southCartographic.longitude = longitude;
      southCartographic.latitude = south;
      southCartographic.height = 0.0;

      var ellipsoidGeodesic = viewRectangle3DEllipsoidGeodesic;
      if (
        !defined(ellipsoidGeodesic) ||
        ellipsoidGeodesic.ellipsoid !== ellipsoid
      ) {
        viewRectangle3DEllipsoidGeodesic = ellipsoidGeodesic = new EllipsoidGeodesic(
          undefined,
          undefined,
          ellipsoid
        );
      }

      ellipsoidGeodesic.setEndPoints(northCartographic, southCartographic);
      latitude = ellipsoidGeodesic.interpolateUsingFraction(
        0.5,
        viewRectangle3DCartographic1
      ).latitude;
    }

    var centerCartographic = viewRectangle3DCartographic1;
    centerCartographic.longitude = longitude;
    centerCartographic.latitude = latitude;
    centerCartographic.height = 0.0;

    var center = ellipsoid.cartographicToCartesian(
      centerCartographic,
      viewRectangle3DCenter
    );

    var cart = viewRectangle3DCartographic1;
    cart.longitude = east;
    cart.latitude = north;
    var northEast = ellipsoid.cartographicToCartesian(
      cart,
      viewRectangle3DNorthEast
    );
    cart.longitude = west;
    var northWest = ellipsoid.cartographicToCartesian(
      cart,
      viewRectangle3DNorthWest
    );
    cart.longitude = longitude;
    var northCenter = ellipsoid.cartographicToCartesian(
      cart,
      viewRectangle3DNorthCenter
    );
    cart.latitude = south;
    var southCenter = ellipsoid.cartographicToCartesian(
      cart,
      viewRectangle3DSouthCenter
    );
    cart.longitude = east;
    var southEast = ellipsoid.cartographicToCartesian(
      cart,
      viewRectangle3DSouthEast
    );
    cart.longitude = west;
    var southWest = ellipsoid.cartographicToCartesian(
      cart,
      viewRectangle3DSouthWest
    );

    Cartesian3.subtract(northWest, center, northWest);
    Cartesian3.subtract(southEast, center, southEast);
    Cartesian3.subtract(northEast, center, northEast);
    Cartesian3.subtract(southWest, center, southWest);
    Cartesian3.subtract(northCenter, center, northCenter);
    Cartesian3.subtract(southCenter, center, southCenter);

    var direction = ellipsoid.geodeticSurfaceNormal(center, cameraRF.direction);
    Cartesian3.negate(direction, direction);
    var right = Cartesian3.cross(direction, Cartesian3.UNIT_Z, cameraRF.right);
    Cartesian3.normalize(right, right);
    var up = Cartesian3.cross(right, direction, cameraRF.up);

    var d;
    if (camera.frustum instanceof OrthographicFrustum) {
      var width = Math.max(
        Cartesian3.distance(northEast, northWest),
        Cartesian3.distance(southEast, southWest)
      );
      var height = Math.max(
        Cartesian3.distance(northEast, southEast),
        Cartesian3.distance(northWest, southWest)
      );

      var rightScalar;
      var topScalar;
      var ratio =
        camera.frustum._offCenterFrustum.right /
        camera.frustum._offCenterFrustum.top;
      var heightRatio = height * ratio;
      if (width > heightRatio) {
        rightScalar = width;
        topScalar = rightScalar / ratio;
      } else {
        topScalar = height;
        rightScalar = heightRatio;
      }

      d = Math.max(rightScalar, topScalar);
    } else {
      var tanPhi = Math.tan(camera.frustum.fovy * 0.5);
      var tanTheta = camera.frustum.aspectRatio * tanPhi;

      d = Math.max(
        computeD(direction, up, northWest, tanPhi),
        computeD(direction, up, southEast, tanPhi),
        computeD(direction, up, northEast, tanPhi),
        computeD(direction, up, southWest, tanPhi),
        computeD(direction, up, northCenter, tanPhi),
        computeD(direction, up, southCenter, tanPhi),
        computeD(direction, right, northWest, tanTheta),
        computeD(direction, right, southEast, tanTheta),
        computeD(direction, right, northEast, tanTheta),
        computeD(direction, right, southWest, tanTheta),
        computeD(direction, right, northCenter, tanTheta),
        computeD(direction, right, southCenter, tanTheta)
      );

      // If the rectangle crosses the equator, compute D at the equator, too, because that's the
      // widest part of the rectangle when projected onto the globe.
      if (south < 0 && north > 0) {
        var equatorCartographic = viewRectangle3DCartographic1;
        equatorCartographic.longitude = west;
        equatorCartographic.latitude = 0.0;
        equatorCartographic.height = 0.0;
        var equatorPosition = ellipsoid.cartographicToCartesian(
          equatorCartographic,
          viewRectangle3DEquator
        );
        Cartesian3.subtract(equatorPosition, center, equatorPosition);
        d = Math.max(
          d,
          computeD(direction, up, equatorPosition, tanPhi),
          computeD(direction, right, equatorPosition, tanTheta)
        );

        equatorCartographic.longitude = east;
        equatorPosition = ellipsoid.cartographicToCartesian(
          equatorCartographic,
          viewRectangle3DEquator
        );
        Cartesian3.subtract(equatorPosition, center, equatorPosition);
        d = Math.max(
          d,
          computeD(direction, up, equatorPosition, tanPhi),
          computeD(direction, right, equatorPosition, tanTheta)
        );
      }
    }

    return Cartesian3.add(
      center,
      Cartesian3.multiplyByScalar(direction, -d, viewRectangle3DEquator),
      result
    );
  }

  var viewRectangleCVCartographic = new Cartographic();
  var viewRectangleCVNorthEast = new Cartesian3();
  var viewRectangleCVSouthWest = new Cartesian3();
  function rectangleCameraPositionColumbusView(camera, rectangle, result) {
    var projection = camera._projection;
    if (rectangle.west > rectangle.east) {
      rectangle = Rectangle.MAX_VALUE;
    }
    var transform = camera._actualTransform;
    var invTransform = camera._actualInvTransform;

    var cart = viewRectangleCVCartographic;
    cart.longitude = rectangle.east;
    cart.latitude = rectangle.north;
    var northEast = projection.project(cart, viewRectangleCVNorthEast);
    Matrix4.multiplyByPoint(transform, northEast, northEast);
    Matrix4.multiplyByPoint(invTransform, northEast, northEast);

    cart.longitude = rectangle.west;
    cart.latitude = rectangle.south;
    var southWest = projection.project(cart, viewRectangleCVSouthWest);
    Matrix4.multiplyByPoint(transform, southWest, southWest);
    Matrix4.multiplyByPoint(invTransform, southWest, southWest);

    result.x = (northEast.x - southWest.x) * 0.5 + southWest.x;
    result.y = (northEast.y - southWest.y) * 0.5 + southWest.y;

    if (defined(camera.frustum.fovy)) {
      var tanPhi = Math.tan(camera.frustum.fovy * 0.5);
      var tanTheta = camera.frustum.aspectRatio * tanPhi;
      result.z =
        Math.max(
          (northEast.x - southWest.x) / tanTheta,
          (northEast.y - southWest.y) / tanPhi
        ) * 0.5;
    } else {
      var width = northEast.x - southWest.x;
      var height = northEast.y - southWest.y;
      result.z = Math.max(width, height);
    }

    return result;
  }

  var viewRectangle2DCartographic = new Cartographic();
  var viewRectangle2DNorthEast = new Cartesian3();
  var viewRectangle2DSouthWest = new Cartesian3();
  function rectangleCameraPosition2D(camera, rectangle, result) {
    var projection = camera._projection;

    // Account for the rectangle crossing the International Date Line in 2D mode
    var east = rectangle.east;
    if (rectangle.west > rectangle.east) {
      if (camera._scene.mapMode2D === MapMode2D$1.INFINITE_SCROLL) {
        east += CesiumMath.TWO_PI;
      } else {
        rectangle = Rectangle.MAX_VALUE;
        east = rectangle.east;
      }
    }

    var cart = viewRectangle2DCartographic;
    cart.longitude = east;
    cart.latitude = rectangle.north;
    var northEast = projection.project(cart, viewRectangle2DNorthEast);
    cart.longitude = rectangle.west;
    cart.latitude = rectangle.south;
    var southWest = projection.project(cart, viewRectangle2DSouthWest);

    var width = Math.abs(northEast.x - southWest.x) * 0.5;
    var height = Math.abs(northEast.y - southWest.y) * 0.5;

    var right, top;
    var ratio = camera.frustum.right / camera.frustum.top;
    var heightRatio = height * ratio;
    if (width > heightRatio) {
      right = width;
      top = right / ratio;
    } else {
      top = height;
      right = heightRatio;
    }

    height = Math.max(2.0 * right, 2.0 * top);

    result.x = (northEast.x - southWest.x) * 0.5 + southWest.x;
    result.y = (northEast.y - southWest.y) * 0.5 + southWest.y;

    cart = projection.unproject(result, cart);
    cart.height = height;
    result = projection.project(cart, result);

    return result;
  }

  /**
   * Get the camera position needed to view a rectangle on an ellipsoid or map
   *
   * @param {Rectangle} rectangle The rectangle to view.
   * @param {Cartesian3} [result] The camera position needed to view the rectangle
   * @returns {Cartesian3} The camera position needed to view the rectangle
   */
  Camera.prototype.getRectangleCameraCoordinates = function (rectangle, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(rectangle)) {
      throw new DeveloperError("rectangle is required");
    }
    //>>includeEnd('debug');
    var mode = this._mode;

    if (!defined(result)) {
      result = new Cartesian3();
    }

    if (mode === SceneMode$1.SCENE3D) {
      return rectangleCameraPosition3D(this, rectangle, result);
    } else if (mode === SceneMode$1.COLUMBUS_VIEW) {
      return rectangleCameraPositionColumbusView(this, rectangle, result);
    } else if (mode === SceneMode$1.SCENE2D) {
      return rectangleCameraPosition2D(this, rectangle, result);
    }

    return undefined;
  };

  var pickEllipsoid3DRay = new Ray();
  function pickEllipsoid3D(camera, windowPosition, ellipsoid, result) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    var ray = camera.getPickRay(windowPosition, pickEllipsoid3DRay);
    var intersection = IntersectionTests.rayEllipsoid(ray, ellipsoid);
    if (!intersection) {
      return undefined;
    }

    var t = intersection.start > 0.0 ? intersection.start : intersection.stop;
    return Ray.getPoint(ray, t, result);
  }

  var pickEllipsoid2DRay = new Ray();
  function pickMap2D(camera, windowPosition, projection, result) {
    var ray = camera.getPickRay(windowPosition, pickEllipsoid2DRay);
    var position = ray.origin;
    position = Cartesian3.fromElements(position.y, position.z, 0.0, position);
    var cart = projection.unproject(position);

    if (
      cart.latitude < -CesiumMath.PI_OVER_TWO ||
      cart.latitude > CesiumMath.PI_OVER_TWO
    ) {
      return undefined;
    }

    return projection.ellipsoid.cartographicToCartesian(cart, result);
  }

  var pickEllipsoidCVRay = new Ray();
  function pickMapColumbusView(camera, windowPosition, projection, result) {
    var ray = camera.getPickRay(windowPosition, pickEllipsoidCVRay);
    var scalar = -ray.origin.x / ray.direction.x;
    Ray.getPoint(ray, scalar, result);

    var cart = projection.unproject(new Cartesian3(result.y, result.z, 0.0));

    if (
      cart.latitude < -CesiumMath.PI_OVER_TWO ||
      cart.latitude > CesiumMath.PI_OVER_TWO ||
      cart.longitude < -Math.PI ||
      cart.longitude > Math.PI
    ) {
      return undefined;
    }

    return projection.ellipsoid.cartographicToCartesian(cart, result);
  }

  /**
   * Pick an ellipsoid or map.
   *
   * @param {Cartesian2} windowPosition The x and y coordinates of a pixel.
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid to pick.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3 | undefined} If the ellipsoid or map was picked,
   * returns the point on the surface of the ellipsoid or map in world
   * coordinates. If the ellipsoid or map was not picked, returns undefined.
   *
   * @example
   * var canvas = viewer.scene.canvas;
   * var center = new Cesium.Cartesian2(canvas.clientWidth / 2.0, canvas.clientHeight / 2.0);
   * var ellipsoid = viewer.scene.globe.ellipsoid;
   * var result = viewer.camera.pickEllipsoid(center, ellipsoid);
   */
  Camera.prototype.pickEllipsoid = function (windowPosition, ellipsoid, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(windowPosition)) {
      throw new DeveloperError("windowPosition is required.");
    }
    //>>includeEnd('debug');

    var canvas = this._scene.canvas;
    if (canvas.clientWidth === 0 || canvas.clientHeight === 0) {
      return undefined;
    }

    if (!defined(result)) {
      result = new Cartesian3();
    }

    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    if (this._mode === SceneMode$1.SCENE3D) {
      result = pickEllipsoid3D(this, windowPosition, ellipsoid, result);
    } else if (this._mode === SceneMode$1.SCENE2D) {
      result = pickMap2D(this, windowPosition, this._projection, result);
    } else if (this._mode === SceneMode$1.COLUMBUS_VIEW) {
      result = pickMapColumbusView(
        this,
        windowPosition,
        this._projection,
        result
      );
    } else {
      return undefined;
    }

    return result;
  };

  var pickPerspCenter = new Cartesian3();
  var pickPerspXDir = new Cartesian3();
  var pickPerspYDir = new Cartesian3();
  function getPickRayPerspective(camera, windowPosition, result) {
    var canvas = camera._scene.canvas;
    var width = canvas.clientWidth;
    var height = canvas.clientHeight;

    var tanPhi = Math.tan(camera.frustum.fovy * 0.5);
    var tanTheta = camera.frustum.aspectRatio * tanPhi;
    var near = camera.frustum.near;

    var x = (2.0 / width) * windowPosition.x - 1.0;
    var y = (2.0 / height) * (height - windowPosition.y) - 1.0;

    var position = camera.positionWC;
    Cartesian3.clone(position, result.origin);

    var nearCenter = Cartesian3.multiplyByScalar(
      camera.directionWC,
      near,
      pickPerspCenter
    );
    Cartesian3.add(position, nearCenter, nearCenter);
    var xDir = Cartesian3.multiplyByScalar(
      camera.rightWC,
      x * near * tanTheta,
      pickPerspXDir
    );
    var yDir = Cartesian3.multiplyByScalar(
      camera.upWC,
      y * near * tanPhi,
      pickPerspYDir
    );
    var direction = Cartesian3.add(nearCenter, xDir, result.direction);
    Cartesian3.add(direction, yDir, direction);
    Cartesian3.subtract(direction, position, direction);
    Cartesian3.normalize(direction, direction);

    return result;
  }

  var scratchDirection$1 = new Cartesian3();

  function getPickRayOrthographic(camera, windowPosition, result) {
    var canvas = camera._scene.canvas;
    var width = canvas.clientWidth;
    var height = canvas.clientHeight;

    var frustum = camera.frustum;
    if (defined(frustum._offCenterFrustum)) {
      frustum = frustum._offCenterFrustum;
    }
    var x = (2.0 / width) * windowPosition.x - 1.0;
    x *= (frustum.right - frustum.left) * 0.5;
    var y = (2.0 / height) * (height - windowPosition.y) - 1.0;
    y *= (frustum.top - frustum.bottom) * 0.5;

    var origin = result.origin;
    Cartesian3.clone(camera.position, origin);

    Cartesian3.multiplyByScalar(camera.right, x, scratchDirection$1);
    Cartesian3.add(scratchDirection$1, origin, origin);
    Cartesian3.multiplyByScalar(camera.up, y, scratchDirection$1);
    Cartesian3.add(scratchDirection$1, origin, origin);

    Cartesian3.clone(camera.directionWC, result.direction);

    if (
      camera._mode === SceneMode$1.COLUMBUS_VIEW ||
      camera._mode === SceneMode$1.SCENE2D
    ) {
      Cartesian3.fromElements(
        result.origin.z,
        result.origin.x,
        result.origin.y,
        result.origin
      );
    }

    return result;
  }

  /**
   * Create a ray from the camera position through the pixel at <code>windowPosition</code>
   * in world coordinates.
   *
   * @param {Cartesian2} windowPosition The x and y coordinates of a pixel.
   * @param {Ray} [result] The object onto which to store the result.
   * @returns {Ray} Returns the {@link Cartesian3} position and direction of the ray.
   */
  Camera.prototype.getPickRay = function (windowPosition, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(windowPosition)) {
      throw new DeveloperError("windowPosition is required.");
    }
    //>>includeEnd('debug');

    if (!defined(result)) {
      result = new Ray();
    }

    var frustum = this.frustum;
    if (
      defined(frustum.aspectRatio) &&
      defined(frustum.fov) &&
      defined(frustum.near)
    ) {
      return getPickRayPerspective(this, windowPosition, result);
    }

    return getPickRayOrthographic(this, windowPosition, result);
  };

  var scratchToCenter$1 = new Cartesian3();
  var scratchProj = new Cartesian3();

  /**
   * Return the distance from the camera to the front of the bounding sphere.
   *
   * @param {BoundingSphere} boundingSphere The bounding sphere in world coordinates.
   * @returns {Number} The distance to the bounding sphere.
   */
  Camera.prototype.distanceToBoundingSphere = function (boundingSphere) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingSphere)) {
      throw new DeveloperError("boundingSphere is required.");
    }
    //>>includeEnd('debug');

    var toCenter = Cartesian3.subtract(
      this.positionWC,
      boundingSphere.center,
      scratchToCenter$1
    );
    var proj = Cartesian3.multiplyByScalar(
      this.directionWC,
      Cartesian3.dot(toCenter, this.directionWC),
      scratchProj
    );
    return Math.max(0.0, Cartesian3.magnitude(proj) - boundingSphere.radius);
  };

  var scratchPixelSize = new Cartesian2();

  /**
   * Return the pixel size in meters.
   *
   * @param {BoundingSphere} boundingSphere The bounding sphere in world coordinates.
   * @param {Number} drawingBufferWidth The drawing buffer width.
   * @param {Number} drawingBufferHeight The drawing buffer height.
   * @returns {Number} The pixel size in meters.
   */
  Camera.prototype.getPixelSize = function (
    boundingSphere,
    drawingBufferWidth,
    drawingBufferHeight
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingSphere)) {
      throw new DeveloperError("boundingSphere is required.");
    }
    if (!defined(drawingBufferWidth)) {
      throw new DeveloperError("drawingBufferWidth is required.");
    }
    if (!defined(drawingBufferHeight)) {
      throw new DeveloperError("drawingBufferHeight is required.");
    }
    //>>includeEnd('debug');

    var distance = this.distanceToBoundingSphere(boundingSphere);
    var pixelSize = this.frustum.getPixelDimensions(
      drawingBufferWidth,
      drawingBufferHeight,
      distance,
      this._scene.pixelRatio,
      scratchPixelSize
    );
    return Math.max(pixelSize.x, pixelSize.y);
  };

  function createAnimationTemplateCV(
    camera,
    position,
    center,
    maxX,
    maxY,
    duration
  ) {
    var newPosition = Cartesian3.clone(position);

    if (center.y > maxX) {
      newPosition.y -= center.y - maxX;
    } else if (center.y < -maxX) {
      newPosition.y += -maxX - center.y;
    }

    if (center.z > maxY) {
      newPosition.z -= center.z - maxY;
    } else if (center.z < -maxY) {
      newPosition.z += -maxY - center.z;
    }

    function updateCV(value) {
      var interp = Cartesian3.lerp(
        position,
        newPosition,
        value.time,
        new Cartesian3()
      );
      camera.worldToCameraCoordinatesPoint(interp, camera.position);
    }
    return {
      easingFunction: EasingFunction$1.EXPONENTIAL_OUT,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: 1.0,
      },
      duration: duration,
      update: updateCV,
    };
  }

  var normalScratch$4 = new Cartesian3();
  var centerScratch$4 = new Cartesian3();
  var posScratch = new Cartesian3();
  var scratchCartesian3Subtract = new Cartesian3();

  function createAnimationCV(camera, duration) {
    var position = camera.position;
    var direction = camera.direction;

    var normal = camera.worldToCameraCoordinatesVector(
      Cartesian3.UNIT_X,
      normalScratch$4
    );
    var scalar =
      -Cartesian3.dot(normal, position) / Cartesian3.dot(normal, direction);
    var center = Cartesian3.add(
      position,
      Cartesian3.multiplyByScalar(direction, scalar, centerScratch$4),
      centerScratch$4
    );
    camera.cameraToWorldCoordinatesPoint(center, center);

    position = camera.cameraToWorldCoordinatesPoint(camera.position, posScratch);

    var tanPhi = Math.tan(camera.frustum.fovy * 0.5);
    var tanTheta = camera.frustum.aspectRatio * tanPhi;
    var distToC = Cartesian3.magnitude(
      Cartesian3.subtract(position, center, scratchCartesian3Subtract)
    );
    var dWidth = tanTheta * distToC;
    var dHeight = tanPhi * distToC;

    var mapWidth = camera._maxCoord.x;
    var mapHeight = camera._maxCoord.y;

    var maxX = Math.max(dWidth - mapWidth, mapWidth);
    var maxY = Math.max(dHeight - mapHeight, mapHeight);

    if (
      position.z < -maxX ||
      position.z > maxX ||
      position.y < -maxY ||
      position.y > maxY
    ) {
      var translateX = center.y < -maxX || center.y > maxX;
      var translateY = center.z < -maxY || center.z > maxY;
      if (translateX || translateY) {
        return createAnimationTemplateCV(
          camera,
          position,
          center,
          maxX,
          maxY,
          duration
        );
      }
    }

    return undefined;
  }

  /**
   * Create an animation to move the map into view. This method is only valid for 2D and Columbus modes.
   *
   * @param {Number} duration The duration, in seconds, of the animation.
   * @returns {Object} The animation or undefined if the scene mode is 3D or the map is already ion view.
   *
   * @private
   */
  Camera.prototype.createCorrectPositionTween = function (duration) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(duration)) {
      throw new DeveloperError("duration is required.");
    }
    //>>includeEnd('debug');

    if (this._mode === SceneMode$1.COLUMBUS_VIEW) {
      return createAnimationCV(this, duration);
    }

    return undefined;
  };

  var scratchFlyToDestination = new Cartesian3();
  var newOptions = {
    destination: undefined,
    heading: undefined,
    pitch: undefined,
    roll: undefined,
    duration: undefined,
    complete: undefined,
    cancel: undefined,
    endTransform: undefined,
    maximumHeight: undefined,
    easingFunction: undefined,
  };

  /**
   * Cancels the current camera flight and leaves the camera at its current location.
   * If no flight is in progress, this this function does nothing.
   */
  Camera.prototype.cancelFlight = function () {
    if (defined(this._currentFlight)) {
      this._currentFlight.cancelTween();
      this._currentFlight = undefined;
    }
  };

  /**
   * Completes the current camera flight and moves the camera immediately to its final destination.
   * If no flight is in progress, this this function does nothing.
   */
  Camera.prototype.completeFlight = function () {
    if (defined(this._currentFlight)) {
      this._currentFlight.cancelTween();

      var options = {
        destination: undefined,
        orientation: {
          heading: undefined,
          pitch: undefined,
          roll: undefined,
        },
      };

      options.destination = newOptions.destination;
      options.orientation.heading = newOptions.heading;
      options.orientation.pitch = newOptions.pitch;
      options.orientation.roll = newOptions.roll;

      this.setView(options);

      if (defined(this._currentFlight.complete)) {
        this._currentFlight.complete();
      }

      this._currentFlight = undefined;
    }
  };

  /**
   * Flies the camera from its current position to a new position.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3|Rectangle} options.destination The final position of the camera in WGS84 (world) coordinates or a rectangle that would be visible from a top-down view.
   * @param {Object} [options.orientation] An object that contains either direction and up properties or heading, pitch and roll properties. By default, the direction will point
   * towards the center of the frame in 3D and in the negative z direction in Columbus view. The up direction will point towards local north in 3D and in the positive
   * y direction in Columbus view.  Orientation is not used in 2D when in infinite scrolling mode.
   * @param {Number} [options.duration] The duration of the flight in seconds. If omitted, Cesium attempts to calculate an ideal duration based on the distance to be traveled by the flight.
   * @param {Camera.FlightCompleteCallback} [options.complete] The function to execute when the flight is complete.
   * @param {Camera.FlightCancelledCallback} [options.cancel] The function to execute if the flight is cancelled.
   * @param {Matrix4} [options.endTransform] Transform matrix representing the reference frame the camera will be in when the flight is completed.
   * @param {Number} [options.maximumHeight] The maximum height at the peak of the flight.
   * @param {Number} [options.pitchAdjustHeight] If camera flyes higher than that value, adjust pitch duiring the flight to look down, and keep Earth in viewport.
   * @param {Number} [options.flyOverLongitude] There are always two ways between 2 points on globe. This option force camera to choose fight direction to fly over that longitude.
   * @param {Number} [options.flyOverLongitudeWeight] Fly over the lon specifyed via flyOverLongitude only if that way is not longer than short way times flyOverLongitudeWeight.
   * @param {Boolean} [options.convert] Whether to convert the destination from world coordinates to scene coordinates (only relevant when not using 3D). Defaults to <code>true</code>.
   * @param {EasingFunction.Callback} [options.easingFunction] Controls how the time is interpolated over the duration of the flight.
   *
   * @exception {DeveloperError} If either direction or up is given, then both are required.
   *
   * @example
   * // 1. Fly to a position with a top-down view
   * viewer.camera.flyTo({
   *     destination : Cesium.Cartesian3.fromDegrees(-117.16, 32.71, 15000.0)
   * });
   *
   * // 2. Fly to a Rectangle with a top-down view
   * viewer.camera.flyTo({
   *     destination : Cesium.Rectangle.fromDegrees(west, south, east, north)
   * });
   *
   * // 3. Fly to a position with an orientation using unit vectors.
   * viewer.camera.flyTo({
   *     destination : Cesium.Cartesian3.fromDegrees(-122.19, 46.25, 5000.0),
   *     orientation : {
   *         direction : new Cesium.Cartesian3(-0.04231243104240401, -0.20123236049443421, -0.97862924300734),
   *         up : new Cesium.Cartesian3(-0.47934589305293746, -0.8553216253114552, 0.1966022179118339)
   *     }
   * });
   *
   * // 4. Fly to a position with an orientation using heading, pitch and roll.
   * viewer.camera.flyTo({
   *     destination : Cesium.Cartesian3.fromDegrees(-122.19, 46.25, 5000.0),
   *     orientation : {
   *         heading : Cesium.Math.toRadians(175.0),
   *         pitch : Cesium.Math.toRadians(-35.0),
   *         roll : 0.0
   *     }
   * });
   */
  Camera.prototype.flyTo = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var destination = options.destination;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(destination)) {
      throw new DeveloperError("destination is required.");
    }
    //>>includeEnd('debug');

    var mode = this._mode;
    if (mode === SceneMode$1.MORPHING) {
      return;
    }

    this.cancelFlight();

    var orientation = defaultValue(
      options.orientation,
      defaultValue.EMPTY_OBJECT
    );
    if (defined(orientation.direction)) {
      orientation = directionUpToHeadingPitchRoll(
        this,
        destination,
        orientation,
        scratchSetViewOptions.orientation
      );
    }

    if (defined(options.duration) && options.duration <= 0.0) {
      var setViewOptions = scratchSetViewOptions;
      setViewOptions.destination = options.destination;
      setViewOptions.orientation.heading = orientation.heading;
      setViewOptions.orientation.pitch = orientation.pitch;
      setViewOptions.orientation.roll = orientation.roll;
      setViewOptions.convert = options.convert;
      setViewOptions.endTransform = options.endTransform;
      this.setView(setViewOptions);
      if (typeof options.complete === "function") {
        options.complete();
      }
      return;
    }

    var isRectangle = defined(destination.west);
    if (isRectangle) {
      destination = this.getRectangleCameraCoordinates(
        destination,
        scratchFlyToDestination
      );
    }

    var that = this;
    var flightTween;

    newOptions.destination = destination;
    newOptions.heading = orientation.heading;
    newOptions.pitch = orientation.pitch;
    newOptions.roll = orientation.roll;
    newOptions.duration = options.duration;
    newOptions.complete = function () {
      if (flightTween === that._currentFlight) {
        that._currentFlight = undefined;
      }
      if (defined(options.complete)) {
        options.complete();
      }
    };
    newOptions.cancel = options.cancel;
    newOptions.endTransform = options.endTransform;
    newOptions.convert = isRectangle ? false : options.convert;
    newOptions.maximumHeight = options.maximumHeight;
    newOptions.pitchAdjustHeight = options.pitchAdjustHeight;
    newOptions.flyOverLongitude = options.flyOverLongitude;
    newOptions.flyOverLongitudeWeight = options.flyOverLongitudeWeight;
    newOptions.easingFunction = options.easingFunction;

    var scene = this._scene;
    var tweenOptions = CameraFlightPath.createTween(scene, newOptions);
    // If the camera doesn't actually need to go anywhere, duration
    // will be 0 and we can just complete the current flight.
    if (tweenOptions.duration === 0) {
      if (typeof tweenOptions.complete === "function") {
        tweenOptions.complete();
      }
      return;
    }
    flightTween = scene.tweens.add(tweenOptions);
    this._currentFlight = flightTween;

    // Save the final destination view information for the PRELOAD_FLIGHT pass.
    var preloadFlightCamera = this._scene.preloadFlightCamera;
    if (this._mode !== SceneMode$1.SCENE2D) {
      if (!defined(preloadFlightCamera)) {
        preloadFlightCamera = Camera.clone(this);
      }
      preloadFlightCamera.setView({
        destination: destination,
        orientation: orientation,
      });

      this._scene.preloadFlightCullingVolume = preloadFlightCamera.frustum.computeCullingVolume(
        preloadFlightCamera.positionWC,
        preloadFlightCamera.directionWC,
        preloadFlightCamera.upWC
      );
    }
  };

  function distanceToBoundingSphere3D(camera, radius) {
    var frustum = camera.frustum;
    var tanPhi = Math.tan(frustum.fovy * 0.5);
    var tanTheta = frustum.aspectRatio * tanPhi;
    return Math.max(radius / tanTheta, radius / tanPhi);
  }

  function distanceToBoundingSphere2D(camera, radius) {
    var frustum = camera.frustum;
    if (defined(frustum._offCenterFrustum)) {
      frustum = frustum._offCenterFrustum;
    }

    var right, top;
    var ratio = frustum.right / frustum.top;
    var heightRatio = radius * ratio;
    if (radius > heightRatio) {
      right = radius;
      top = right / ratio;
    } else {
      top = radius;
      right = heightRatio;
    }

    return Math.max(right, top) * 1.5;
  }

  var MINIMUM_ZOOM = 100.0;

  function adjustBoundingSphereOffset(camera, boundingSphere, offset) {
    offset = HeadingPitchRange.clone(
      defined(offset) ? offset : Camera.DEFAULT_OFFSET
    );

    var minimumZoom =
      camera._scene.screenSpaceCameraController.minimumZoomDistance;
    var maximumZoom =
      camera._scene.screenSpaceCameraController.maximumZoomDistance;
    var range = offset.range;
    if (!defined(range) || range === 0.0) {
      var radius = boundingSphere.radius;
      if (radius === 0.0) {
        offset.range = MINIMUM_ZOOM;
      } else if (
        camera.frustum instanceof OrthographicFrustum ||
        camera._mode === SceneMode$1.SCENE2D
      ) {
        offset.range = distanceToBoundingSphere2D(camera, radius);
      } else {
        offset.range = distanceToBoundingSphere3D(camera, radius);
      }
      offset.range = CesiumMath.clamp(offset.range, minimumZoom, maximumZoom);
    }

    return offset;
  }

  /**
   * Sets the camera so that the current view contains the provided bounding sphere.
   *
   * <p>The offset is heading/pitch/range in the local east-north-up reference frame centered at the center of the bounding sphere.
   * The heading and the pitch angles are defined in the local east-north-up reference frame.
   * The heading is the angle from y axis and increasing towards the x axis. Pitch is the rotation from the xy-plane. Positive pitch
   * angles are below the plane. Negative pitch angles are above the plane. The range is the distance from the center. If the range is
   * zero, a range will be computed such that the whole bounding sphere is visible.</p>
   *
   * <p>In 2D, there must be a top down view. The camera will be placed above the target looking down. The height above the
   * target will be the range. The heading will be determined from the offset. If the heading cannot be
   * determined from the offset, the heading will be north.</p>
   *
   * @param {BoundingSphere} boundingSphere The bounding sphere to view, in world coordinates.
   * @param {HeadingPitchRange} [offset] The offset from the target in the local east-north-up reference frame centered at the target.
   *
   * @exception {DeveloperError} viewBoundingSphere is not supported while morphing.
   */
  Camera.prototype.viewBoundingSphere = function (boundingSphere, offset) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingSphere)) {
      throw new DeveloperError("boundingSphere is required.");
    }

    if (this._mode === SceneMode$1.MORPHING) {
      throw new DeveloperError(
        "viewBoundingSphere is not supported while morphing."
      );
    }
    //>>includeEnd('debug');

    offset = adjustBoundingSphereOffset(this, boundingSphere, offset);
    this.lookAt(boundingSphere.center, offset);
  };

  var scratchflyToBoundingSphereTransform = new Matrix4();
  var scratchflyToBoundingSphereDestination = new Cartesian3();
  var scratchflyToBoundingSphereDirection = new Cartesian3();
  var scratchflyToBoundingSphereUp = new Cartesian3();
  var scratchflyToBoundingSphereRight = new Cartesian3();
  var scratchFlyToBoundingSphereCart4 = new Cartesian4();
  var scratchFlyToBoundingSphereQuaternion = new Quaternion();
  var scratchFlyToBoundingSphereMatrix3 = new Matrix3();

  /**
   * Flies the camera to a location where the current view contains the provided bounding sphere.
   *
   * <p> The offset is heading/pitch/range in the local east-north-up reference frame centered at the center of the bounding sphere.
   * The heading and the pitch angles are defined in the local east-north-up reference frame.
   * The heading is the angle from y axis and increasing towards the x axis. Pitch is the rotation from the xy-plane. Positive pitch
   * angles are below the plane. Negative pitch angles are above the plane. The range is the distance from the center. If the range is
   * zero, a range will be computed such that the whole bounding sphere is visible.</p>
   *
   * <p>In 2D and Columbus View, there must be a top down view. The camera will be placed above the target looking down. The height above the
   * target will be the range. The heading will be aligned to local north.</p>
   *
   * @param {BoundingSphere} boundingSphere The bounding sphere to view, in world coordinates.
   * @param {Object} [options] Object with the following properties:
   * @param {Number} [options.duration] The duration of the flight in seconds. If omitted, Cesium attempts to calculate an ideal duration based on the distance to be traveled by the flight.
   * @param {HeadingPitchRange} [options.offset] The offset from the target in the local east-north-up reference frame centered at the target.
   * @param {Camera.FlightCompleteCallback} [options.complete] The function to execute when the flight is complete.
   * @param {Camera.FlightCancelledCallback} [options.cancel] The function to execute if the flight is cancelled.
   * @param {Matrix4} [options.endTransform] Transform matrix representing the reference frame the camera will be in when the flight is completed.
   * @param {Number} [options.maximumHeight] The maximum height at the peak of the flight.
   * @param {Number} [options.pitchAdjustHeight] If camera flyes higher than that value, adjust pitch duiring the flight to look down, and keep Earth in viewport.
   * @param {Number} [options.flyOverLongitude] There are always two ways between 2 points on globe. This option force camera to choose fight direction to fly over that longitude.
   * @param {Number} [options.flyOverLongitudeWeight] Fly over the lon specifyed via flyOverLongitude only if that way is not longer than short way times flyOverLongitudeWeight.
   * @param {EasingFunction.Callback} [options.easingFunction] Controls how the time is interpolated over the duration of the flight.
   */
  Camera.prototype.flyToBoundingSphere = function (boundingSphere, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(boundingSphere)) {
      throw new DeveloperError("boundingSphere is required.");
    }
    //>>includeEnd('debug');

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var scene2D =
      this._mode === SceneMode$1.SCENE2D || this._mode === SceneMode$1.COLUMBUS_VIEW;
    this._setTransform(Matrix4.IDENTITY);
    var offset = adjustBoundingSphereOffset(this, boundingSphere, options.offset);

    var position;
    if (scene2D) {
      position = Cartesian3.multiplyByScalar(
        Cartesian3.UNIT_Z,
        offset.range,
        scratchflyToBoundingSphereDestination
      );
    } else {
      position = offsetFromHeadingPitchRange(
        offset.heading,
        offset.pitch,
        offset.range
      );
    }

    var transform = Transforms.eastNorthUpToFixedFrame(
      boundingSphere.center,
      Ellipsoid.WGS84,
      scratchflyToBoundingSphereTransform
    );
    Matrix4.multiplyByPoint(transform, position, position);

    var direction;
    var up;

    if (!scene2D) {
      direction = Cartesian3.subtract(
        boundingSphere.center,
        position,
        scratchflyToBoundingSphereDirection
      );
      Cartesian3.normalize(direction, direction);

      up = Matrix4.multiplyByPointAsVector(
        transform,
        Cartesian3.UNIT_Z,
        scratchflyToBoundingSphereUp
      );
      if (1.0 - Math.abs(Cartesian3.dot(direction, up)) < CesiumMath.EPSILON6) {
        var rotateQuat = Quaternion.fromAxisAngle(
          direction,
          offset.heading,
          scratchFlyToBoundingSphereQuaternion
        );
        var rotation = Matrix3.fromQuaternion(
          rotateQuat,
          scratchFlyToBoundingSphereMatrix3
        );

        Cartesian3.fromCartesian4(
          Matrix4.getColumn(transform, 1, scratchFlyToBoundingSphereCart4),
          up
        );
        Matrix3.multiplyByVector(rotation, up, up);
      }

      var right = Cartesian3.cross(
        direction,
        up,
        scratchflyToBoundingSphereRight
      );
      Cartesian3.cross(right, direction, up);
      Cartesian3.normalize(up, up);
    }

    this.flyTo({
      destination: position,
      orientation: {
        direction: direction,
        up: up,
      },
      duration: options.duration,
      complete: options.complete,
      cancel: options.cancel,
      endTransform: options.endTransform,
      maximumHeight: options.maximumHeight,
      easingFunction: options.easingFunction,
      flyOverLongitude: options.flyOverLongitude,
      flyOverLongitudeWeight: options.flyOverLongitudeWeight,
      pitchAdjustHeight: options.pitchAdjustHeight,
    });
  };

  var scratchCartesian3_1 = new Cartesian3();
  var scratchCartesian3_2 = new Cartesian3();
  var scratchCartesian3_3 = new Cartesian3();
  var scratchCartesian3_4 = new Cartesian3();
  var horizonPoints = [
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
  ];

  function computeHorizonQuad(camera, ellipsoid) {
    var radii = ellipsoid.radii;
    var p = camera.positionWC;

    // Find the corresponding position in the scaled space of the ellipsoid.
    var q = Cartesian3.multiplyComponents(
      ellipsoid.oneOverRadii,
      p,
      scratchCartesian3_1
    );

    var qMagnitude = Cartesian3.magnitude(q);
    var qUnit = Cartesian3.normalize(q, scratchCartesian3_2);

    // Determine the east and north directions at q.
    var eUnit;
    var nUnit;
    if (
      Cartesian3.equalsEpsilon(qUnit, Cartesian3.UNIT_Z, CesiumMath.EPSILON10)
    ) {
      eUnit = new Cartesian3(0, 1, 0);
      nUnit = new Cartesian3(0, 0, 1);
    } else {
      eUnit = Cartesian3.normalize(
        Cartesian3.cross(Cartesian3.UNIT_Z, qUnit, scratchCartesian3_3),
        scratchCartesian3_3
      );
      nUnit = Cartesian3.normalize(
        Cartesian3.cross(qUnit, eUnit, scratchCartesian3_4),
        scratchCartesian3_4
      );
    }

    // Determine the radius of the 'limb' of the ellipsoid.
    var wMagnitude = Math.sqrt(Cartesian3.magnitudeSquared(q) - 1.0);

    // Compute the center and offsets.
    var center = Cartesian3.multiplyByScalar(
      qUnit,
      1.0 / qMagnitude,
      scratchCartesian3_1
    );
    var scalar = wMagnitude / qMagnitude;
    var eastOffset = Cartesian3.multiplyByScalar(
      eUnit,
      scalar,
      scratchCartesian3_2
    );
    var northOffset = Cartesian3.multiplyByScalar(
      nUnit,
      scalar,
      scratchCartesian3_3
    );

    // A conservative measure for the longitudes would be to use the min/max longitudes of the bounding frustum.
    var upperLeft = Cartesian3.add(center, northOffset, horizonPoints[0]);
    Cartesian3.subtract(upperLeft, eastOffset, upperLeft);
    Cartesian3.multiplyComponents(radii, upperLeft, upperLeft);

    var lowerLeft = Cartesian3.subtract(center, northOffset, horizonPoints[1]);
    Cartesian3.subtract(lowerLeft, eastOffset, lowerLeft);
    Cartesian3.multiplyComponents(radii, lowerLeft, lowerLeft);

    var lowerRight = Cartesian3.subtract(center, northOffset, horizonPoints[2]);
    Cartesian3.add(lowerRight, eastOffset, lowerRight);
    Cartesian3.multiplyComponents(radii, lowerRight, lowerRight);

    var upperRight = Cartesian3.add(center, northOffset, horizonPoints[3]);
    Cartesian3.add(upperRight, eastOffset, upperRight);
    Cartesian3.multiplyComponents(radii, upperRight, upperRight);

    return horizonPoints;
  }

  var scratchPickCartesian2 = new Cartesian2();
  var scratchRectCartesian = new Cartesian3();
  var cartoArray = [
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
    new Cartographic(),
  ];
  function addToResult(x, y, index, camera, ellipsoid, computedHorizonQuad) {
    scratchPickCartesian2.x = x;
    scratchPickCartesian2.y = y;
    var r = camera.pickEllipsoid(
      scratchPickCartesian2,
      ellipsoid,
      scratchRectCartesian
    );
    if (defined(r)) {
      cartoArray[index] = ellipsoid.cartesianToCartographic(r, cartoArray[index]);
      return 1;
    }
    cartoArray[index] = ellipsoid.cartesianToCartographic(
      computedHorizonQuad[index],
      cartoArray[index]
    );
    return 0;
  }
  /**
   * Computes the approximate visible rectangle on the ellipsoid.
   *
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid that you want to know the visible region.
   * @param {Rectangle} [result] The rectangle in which to store the result
   *
   * @returns {Rectangle|undefined} The visible rectangle or undefined if the ellipsoid isn't visible at all.
   */
  Camera.prototype.computeViewRectangle = function (ellipsoid, result) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    var cullingVolume = this.frustum.computeCullingVolume(
      this.positionWC,
      this.directionWC,
      this.upWC
    );
    var boundingSphere = new BoundingSphere(
      Cartesian3.ZERO,
      ellipsoid.maximumRadius
    );
    var visibility = cullingVolume.computeVisibility(boundingSphere);
    if (visibility === Intersect$1.OUTSIDE) {
      return undefined;
    }

    var canvas = this._scene.canvas;
    var width = canvas.clientWidth;
    var height = canvas.clientHeight;

    var successfulPickCount = 0;

    var computedHorizonQuad = computeHorizonQuad(this, ellipsoid);

    successfulPickCount += addToResult(
      0,
      0,
      0,
      this,
      ellipsoid,
      computedHorizonQuad
    );
    successfulPickCount += addToResult(
      0,
      height,
      1,
      this,
      ellipsoid,
      computedHorizonQuad
    );
    successfulPickCount += addToResult(
      width,
      height,
      2,
      this,
      ellipsoid,
      computedHorizonQuad
    );
    successfulPickCount += addToResult(
      width,
      0,
      3,
      this,
      ellipsoid,
      computedHorizonQuad
    );

    if (successfulPickCount < 2) {
      // If we have space non-globe in 3 or 4 corners then return the whole globe
      return Rectangle.MAX_VALUE;
    }

    result = Rectangle.fromCartographicArray(cartoArray, result);

    // Detect if we go over the poles
    var distance = 0;
    var lastLon = cartoArray[3].longitude;
    for (var i = 0; i < 4; ++i) {
      var lon = cartoArray[i].longitude;
      var diff = Math.abs(lon - lastLon);
      if (diff > CesiumMath.PI) {
        // Crossed the dateline
        distance += CesiumMath.TWO_PI - diff;
      } else {
        distance += diff;
      }

      lastLon = lon;
    }

    // We are over one of the poles so adjust the rectangle accordingly
    if (
      CesiumMath.equalsEpsilon(
        Math.abs(distance),
        CesiumMath.TWO_PI,
        CesiumMath.EPSILON9
      )
    ) {
      result.west = -CesiumMath.PI;
      result.east = CesiumMath.PI;
      if (cartoArray[0].latitude >= 0.0) {
        result.north = CesiumMath.PI_OVER_TWO;
      } else {
        result.south = -CesiumMath.PI_OVER_TWO;
      }
    }

    return result;
  };

  /**
   * Switches the frustum/projection to perspective.
   *
   * This function is a no-op in 2D which must always be orthographic.
   */
  Camera.prototype.switchToPerspectiveFrustum = function () {
    if (
      this._mode === SceneMode$1.SCENE2D ||
      this.frustum instanceof PerspectiveFrustum
    ) {
      return;
    }

    var scene = this._scene;
    this.frustum = new PerspectiveFrustum();
    this.frustum.aspectRatio =
      scene.drawingBufferWidth / scene.drawingBufferHeight;
    this.frustum.fov = CesiumMath.toRadians(60.0);
  };

  /**
   * Switches the frustum/projection to orthographic.
   *
   * This function is a no-op in 2D which will always be orthographic.
   */
  Camera.prototype.switchToOrthographicFrustum = function () {
    if (
      this._mode === SceneMode$1.SCENE2D ||
      this.frustum instanceof OrthographicFrustum
    ) {
      return;
    }

    // This must be called before changing the frustum because it uses the previous
    // frustum to reconstruct the world space position from the depth buffer.
    var frustumWidth = calculateOrthographicFrustumWidth(this);

    var scene = this._scene;
    this.frustum = new OrthographicFrustum();
    this.frustum.aspectRatio =
      scene.drawingBufferWidth / scene.drawingBufferHeight;
    this.frustum.width = frustumWidth;
  };

  /**
   * @private
   */
  Camera.clone = function (camera, result) {
    if (!defined(result)) {
      result = new Camera(camera._scene);
    }

    Cartesian3.clone(camera.position, result.position);
    Cartesian3.clone(camera.direction, result.direction);
    Cartesian3.clone(camera.up, result.up);
    Cartesian3.clone(camera.right, result.right);
    Matrix4.clone(camera._transform, result.transform);
    result._transformChanged = true;
    result.frustum = camera.frustum.clone();

    return result;
  };

  /**
   * Enumerates the available input for interacting with the camera.
   *
   * @enum {Number}
   */
  var CameraEventType = {
    /**
     * A left mouse button press followed by moving the mouse and releasing the button.
     *
     * @type {Number}
     * @constant
     */
    LEFT_DRAG: 0,

    /**
     *  A right mouse button press followed by moving the mouse and releasing the button.
     *
     * @type {Number}
     * @constant
     */
    RIGHT_DRAG: 1,

    /**
     *  A middle mouse button press followed by moving the mouse and releasing the button.
     *
     * @type {Number}
     * @constant
     */
    MIDDLE_DRAG: 2,

    /**
     * Scrolling the middle mouse button.
     *
     * @type {Number}
     * @constant
     */
    WHEEL: 3,

    /**
     * A two-finger touch on a touch surface.
     *
     * @type {Number}
     * @constant
     */
    PINCH: 4,
  };
  var CameraEventType$1 = Object.freeze(CameraEventType);

  function getKey(type, modifier) {
    var key = type;
    if (defined(modifier)) {
      key += "+" + modifier;
    }
    return key;
  }

  function clonePinchMovement(pinchMovement, result) {
    Cartesian2.clone(
      pinchMovement.distance.startPosition,
      result.distance.startPosition
    );
    Cartesian2.clone(
      pinchMovement.distance.endPosition,
      result.distance.endPosition
    );

    Cartesian2.clone(
      pinchMovement.angleAndHeight.startPosition,
      result.angleAndHeight.startPosition
    );
    Cartesian2.clone(
      pinchMovement.angleAndHeight.endPosition,
      result.angleAndHeight.endPosition
    );
  }

  function listenToPinch(aggregator, modifier, canvas) {
    var key = getKey(CameraEventType$1.PINCH, modifier);

    var update = aggregator._update;
    var isDown = aggregator._isDown;
    var eventStartPosition = aggregator._eventStartPosition;
    var pressTime = aggregator._pressTime;
    var releaseTime = aggregator._releaseTime;

    update[key] = true;
    isDown[key] = false;
    eventStartPosition[key] = new Cartesian2();

    var movement = aggregator._movement[key];
    if (!defined(movement)) {
      movement = aggregator._movement[key] = {};
    }

    movement.distance = {
      startPosition: new Cartesian2(),
      endPosition: new Cartesian2(),
    };
    movement.angleAndHeight = {
      startPosition: new Cartesian2(),
      endPosition: new Cartesian2(),
    };
    movement.prevAngle = 0.0;

    aggregator._eventHandler.setInputAction(
      function (event) {
        aggregator._buttonsDown++;
        isDown[key] = true;
        pressTime[key] = new Date();
        // Compute center position and store as start point.
        Cartesian2.lerp(
          event.position1,
          event.position2,
          0.5,
          eventStartPosition[key]
        );
      },
      ScreenSpaceEventType$1.PINCH_START,
      modifier
    );

    aggregator._eventHandler.setInputAction(
      function () {
        aggregator._buttonsDown = Math.max(aggregator._buttonsDown - 1, 0);
        isDown[key] = false;
        releaseTime[key] = new Date();
      },
      ScreenSpaceEventType$1.PINCH_END,
      modifier
    );

    aggregator._eventHandler.setInputAction(
      function (mouseMovement) {
        if (isDown[key]) {
          // Aggregate several input events into a single animation frame.
          if (!update[key]) {
            Cartesian2.clone(
              mouseMovement.distance.endPosition,
              movement.distance.endPosition
            );
            Cartesian2.clone(
              mouseMovement.angleAndHeight.endPosition,
              movement.angleAndHeight.endPosition
            );
          } else {
            clonePinchMovement(mouseMovement, movement);
            update[key] = false;
            movement.prevAngle = movement.angleAndHeight.startPosition.x;
          }
          // Make sure our aggregation of angles does not "flip" over 360 degrees.
          var angle = movement.angleAndHeight.endPosition.x;
          var prevAngle = movement.prevAngle;
          var TwoPI = Math.PI * 2;
          while (angle >= prevAngle + Math.PI) {
            angle -= TwoPI;
          }
          while (angle < prevAngle - Math.PI) {
            angle += TwoPI;
          }
          movement.angleAndHeight.endPosition.x =
            (-angle * canvas.clientWidth) / 12;
          movement.angleAndHeight.startPosition.x =
            (-prevAngle * canvas.clientWidth) / 12;
        }
      },
      ScreenSpaceEventType$1.PINCH_MOVE,
      modifier
    );
  }

  function listenToWheel(aggregator, modifier) {
    var key = getKey(CameraEventType$1.WHEEL, modifier);

    var update = aggregator._update;
    update[key] = true;

    var movement = aggregator._movement[key];
    if (!defined(movement)) {
      movement = aggregator._movement[key] = {};
    }

    movement.startPosition = new Cartesian2();
    movement.endPosition = new Cartesian2();

    aggregator._eventHandler.setInputAction(
      function (delta) {
        // TODO: magic numbers
        var arcLength = 15.0 * CesiumMath.toRadians(delta);
        if (!update[key]) {
          movement.endPosition.y = movement.endPosition.y + arcLength;
        } else {
          Cartesian2.clone(Cartesian2.ZERO, movement.startPosition);
          movement.endPosition.x = 0.0;
          movement.endPosition.y = arcLength;
          update[key] = false;
        }
      },
      ScreenSpaceEventType$1.WHEEL,
      modifier
    );
  }

  function listenMouseButtonDownUp(aggregator, modifier, type) {
    var key = getKey(type, modifier);

    var isDown = aggregator._isDown;
    var eventStartPosition = aggregator._eventStartPosition;
    var pressTime = aggregator._pressTime;
    var releaseTime = aggregator._releaseTime;

    isDown[key] = false;
    eventStartPosition[key] = new Cartesian2();

    var lastMovement = aggregator._lastMovement[key];
    if (!defined(lastMovement)) {
      lastMovement = aggregator._lastMovement[key] = {
        startPosition: new Cartesian2(),
        endPosition: new Cartesian2(),
        valid: false,
      };
    }

    var down;
    var up;
    if (type === CameraEventType$1.LEFT_DRAG) {
      down = ScreenSpaceEventType$1.LEFT_DOWN;
      up = ScreenSpaceEventType$1.LEFT_UP;
    } else if (type === CameraEventType$1.RIGHT_DRAG) {
      down = ScreenSpaceEventType$1.RIGHT_DOWN;
      up = ScreenSpaceEventType$1.RIGHT_UP;
    } else if (type === CameraEventType$1.MIDDLE_DRAG) {
      down = ScreenSpaceEventType$1.MIDDLE_DOWN;
      up = ScreenSpaceEventType$1.MIDDLE_UP;
    }

    aggregator._eventHandler.setInputAction(
      function (event) {
        aggregator._buttonsDown++;
        lastMovement.valid = false;
        isDown[key] = true;
        pressTime[key] = new Date();
        Cartesian2.clone(event.position, eventStartPosition[key]);
      },
      down,
      modifier
    );

    aggregator._eventHandler.setInputAction(
      function () {
        aggregator._buttonsDown = Math.max(aggregator._buttonsDown - 1, 0);
        isDown[key] = false;
        releaseTime[key] = new Date();
      },
      up,
      modifier
    );
  }

  function cloneMouseMovement(mouseMovement, result) {
    Cartesian2.clone(mouseMovement.startPosition, result.startPosition);
    Cartesian2.clone(mouseMovement.endPosition, result.endPosition);
  }

  function listenMouseMove(aggregator, modifier) {
    var update = aggregator._update;
    var movement = aggregator._movement;
    var lastMovement = aggregator._lastMovement;
    var isDown = aggregator._isDown;

    for (var typeName in CameraEventType$1) {
      if (CameraEventType$1.hasOwnProperty(typeName)) {
        var type = CameraEventType$1[typeName];
        if (defined(type)) {
          var key = getKey(type, modifier);
          update[key] = true;

          if (!defined(aggregator._lastMovement[key])) {
            aggregator._lastMovement[key] = {
              startPosition: new Cartesian2(),
              endPosition: new Cartesian2(),
              valid: false,
            };
          }

          if (!defined(aggregator._movement[key])) {
            aggregator._movement[key] = {
              startPosition: new Cartesian2(),
              endPosition: new Cartesian2(),
            };
          }
        }
      }
    }

    aggregator._eventHandler.setInputAction(
      function (mouseMovement) {
        for (var typeName in CameraEventType$1) {
          if (CameraEventType$1.hasOwnProperty(typeName)) {
            var type = CameraEventType$1[typeName];
            if (defined(type)) {
              var key = getKey(type, modifier);
              if (isDown[key]) {
                if (!update[key]) {
                  Cartesian2.clone(
                    mouseMovement.endPosition,
                    movement[key].endPosition
                  );
                } else {
                  cloneMouseMovement(movement[key], lastMovement[key]);
                  lastMovement[key].valid = true;
                  cloneMouseMovement(mouseMovement, movement[key]);
                  update[key] = false;
                }
              }
            }
          }
        }

        Cartesian2.clone(
          mouseMovement.endPosition,
          aggregator._currentMousePosition
        );
      },
      ScreenSpaceEventType$1.MOUSE_MOVE,
      modifier
    );
  }

  /**
   * Aggregates input events. For example, suppose the following inputs are received between frames:
   * left mouse button down, mouse move, mouse move, left mouse button up. These events will be aggregated into
   * one event with a start and end position of the mouse.
   *
   * @alias CameraEventAggregator
   * @constructor
   *
   * @param {HTMLCanvasElement} [canvas=document] The element to handle events for.
   *
   * @see ScreenSpaceEventHandler
   */
  function CameraEventAggregator(canvas) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(canvas)) {
      throw new DeveloperError("canvas is required.");
    }
    //>>includeEnd('debug');

    this._eventHandler = new ScreenSpaceEventHandler(canvas);

    this._update = {};
    this._movement = {};
    this._lastMovement = {};
    this._isDown = {};
    this._eventStartPosition = {};
    this._pressTime = {};
    this._releaseTime = {};

    this._buttonsDown = 0;

    this._currentMousePosition = new Cartesian2();

    listenToWheel(this, undefined);
    listenToPinch(this, undefined, canvas);
    listenMouseButtonDownUp(this, undefined, CameraEventType$1.LEFT_DRAG);
    listenMouseButtonDownUp(this, undefined, CameraEventType$1.RIGHT_DRAG);
    listenMouseButtonDownUp(this, undefined, CameraEventType$1.MIDDLE_DRAG);
    listenMouseMove(this, undefined);

    for (var modifierName in KeyboardEventModifier$1) {
      if (KeyboardEventModifier$1.hasOwnProperty(modifierName)) {
        var modifier = KeyboardEventModifier$1[modifierName];
        if (defined(modifier)) {
          listenToWheel(this, modifier);
          listenToPinch(this, modifier, canvas);
          listenMouseButtonDownUp(this, modifier, CameraEventType$1.LEFT_DRAG);
          listenMouseButtonDownUp(this, modifier, CameraEventType$1.RIGHT_DRAG);
          listenMouseButtonDownUp(this, modifier, CameraEventType$1.MIDDLE_DRAG);
          listenMouseMove(this, modifier);
        }
      }
    }
  }

  Object.defineProperties(CameraEventAggregator.prototype, {
    /**
     * Gets the current mouse position.
     * @memberof CameraEventAggregator.prototype
     * @type {Cartesian2}
     */
    currentMousePosition: {
      get: function () {
        return this._currentMousePosition;
      },
    },

    /**
     * Gets whether any mouse button is down, a touch has started, or the wheel has been moved.
     * @memberof CameraEventAggregator.prototype
     * @type {Boolean}
     */
    anyButtonDown: {
      get: function () {
        var wheelMoved =
          !this._update[getKey(CameraEventType$1.WHEEL)] ||
          !this._update[
            getKey(CameraEventType$1.WHEEL, KeyboardEventModifier$1.SHIFT)
          ] ||
          !this._update[
            getKey(CameraEventType$1.WHEEL, KeyboardEventModifier$1.CTRL)
          ] ||
          !this._update[getKey(CameraEventType$1.WHEEL, KeyboardEventModifier$1.ALT)];
        return this._buttonsDown > 0 || wheelMoved;
      },
    },
  });

  /**
   * Gets if a mouse button down or touch has started and has been moved.
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Boolean} Returns <code>true</code> if a mouse button down or touch has started and has been moved; otherwise, <code>false</code>
   */
  CameraEventAggregator.prototype.isMoving = function (type, modifier) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getKey(type, modifier);
    return !this._update[key];
  };

  /**
   * Gets the aggregated start and end position of the current event.
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Object} An object with two {@link Cartesian2} properties: <code>startPosition</code> and <code>endPosition</code>.
   */
  CameraEventAggregator.prototype.getMovement = function (type, modifier) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getKey(type, modifier);
    var movement = this._movement[key];
    return movement;
  };

  /**
   * Gets the start and end position of the last move event (not the aggregated event).
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Object|undefined} An object with two {@link Cartesian2} properties: <code>startPosition</code> and <code>endPosition</code> or <code>undefined</code>.
   */
  CameraEventAggregator.prototype.getLastMovement = function (type, modifier) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getKey(type, modifier);
    var lastMovement = this._lastMovement[key];
    if (lastMovement.valid) {
      return lastMovement;
    }

    return undefined;
  };

  /**
   * Gets whether the mouse button is down or a touch has started.
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Boolean} Whether the mouse button is down or a touch has started.
   */
  CameraEventAggregator.prototype.isButtonDown = function (type, modifier) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getKey(type, modifier);
    return this._isDown[key];
  };

  /**
   * Gets the mouse position that started the aggregation.
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Cartesian2} The mouse position.
   */
  CameraEventAggregator.prototype.getStartMousePosition = function (
    type,
    modifier
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    if (type === CameraEventType$1.WHEEL) {
      return this._currentMousePosition;
    }

    var key = getKey(type, modifier);
    return this._eventStartPosition[key];
  };

  /**
   * Gets the time the button was pressed or the touch was started.
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Date} The time the button was pressed or the touch was started.
   */
  CameraEventAggregator.prototype.getButtonPressTime = function (type, modifier) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getKey(type, modifier);
    return this._pressTime[key];
  };

  /**
   * Gets the time the button was released or the touch was ended.
   *
   * @param {CameraEventType} type The camera event type.
   * @param {KeyboardEventModifier} [modifier] The keyboard modifier.
   * @returns {Date} The time the button was released or the touch was ended.
   */
  CameraEventAggregator.prototype.getButtonReleaseTime = function (
    type,
    modifier
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    var key = getKey(type, modifier);
    return this._releaseTime[key];
  };

  /**
   * Signals that all of the events have been handled and the aggregator should be reset to handle new events.
   */
  CameraEventAggregator.prototype.reset = function () {
    for (var name in this._update) {
      if (this._update.hasOwnProperty(name)) {
        this._update[name] = true;
      }
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see CameraEventAggregator#destroy
   */
  CameraEventAggregator.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes mouse listeners held by this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * handler = handler && handler.destroy();
   *
   * @see CameraEventAggregator#isDestroyed
   */
  CameraEventAggregator.prototype.destroy = function () {
    this._eventHandler = this._eventHandler && this._eventHandler.destroy();
    return destroyObject(this);
  };

  /**
   * The content of a tile in a {@link Cesium3DTileset}.
   * <p>
   * Derived classes of this interface provide access to individual features in the tile.
   * Access derived objects through {@link Cesium3DTile#content}.
   * </p>
   * <p>
   * This type describes an interface and is not intended to be instantiated directly.
   * </p>
   *
   * @alias Cesium3DTileContent
   * @constructor
   */
  function Cesium3DTileContent(tileset, tile, url, arrayBuffer, byteOffset) {
    /**
     * Gets or sets if any feature's property changed.  Used to
     * optimized applying a style when a feature's property changed.
     * <p>
     * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
     * not part of the public Cesium API.
     * </p>
     *
     * @type {Boolean}
     *
     * @private
     */
    this.featurePropertiesDirty = false;
  }

  Object.defineProperties(Cesium3DTileContent.prototype, {
    /**
     * Gets the number of features in the tile.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Number}
     * @readonly
     */
    featuresLength: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the number of points in the tile.
     * <p>
     * Only applicable for tiles with Point Cloud content. This is different than {@link Cesium3DTileContent#featuresLength} which
     * equals the number of groups of points as distinguished by the <code>BATCH_ID</code> feature table semantic.
     * </p>
     *
     * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/PointCloud#batched-points}
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Number}
     * @readonly
     */
    pointsLength: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the number of triangles in the tile.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Number}
     * @readonly
     */
    trianglesLength: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the tile's geometry memory in bytes.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Number}
     * @readonly
     */
    geometryByteLength: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the tile's texture memory in bytes.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Number}
     * @readonly
     */
    texturesByteLength: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the amount of memory used by the batch table textures, in bytes.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Number}
     * @readonly
     */
    batchTableByteLength: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the array of {@link Cesium3DTileContent} objects that represent the
     * content a composite's inner tiles, which can also be composites.
     *
     * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Composite}
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Array}
     * @readonly
     */
    innerContents: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the promise that will be resolved when the tile's content is ready to render.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Promise.<Cesium3DTileContent>}
     * @readonly
     */
    readyPromise: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the tileset for this tile.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Cesium3DTileset}
     * @readonly
     */
    tileset: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the tile containing this content.
     *
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {Cesium3DTile}
     * @readonly
     */
    tile: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the url of the tile's content.
     * @memberof Cesium3DTileContent.prototype
     *
     * @type {String}
     * @readonly
     */
    url: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },

    /**
     * Gets the batch table for this content.
     * <p>
     * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
     * not part of the public Cesium API.
     * </p>
     *
     * @type {Cesium3DTileBatchTable}
     * @readonly
     *
     * @private
     */
    batchTable: {
      // eslint-disable-next-line getter-return
      get: function () {
        DeveloperError.throwInstantiationError();
      },
    },
  });

  /**
   * Determines if the tile's batch table has a property.  If it does, each feature in
   * the tile will have the property.
   *
   * @param {Number} batchId The batchId for the feature.
   * @param {String} name The case-sensitive name of the property.
   * @returns {Boolean} <code>true</code> if the property exists; otherwise, <code>false</code>.
   */
  Cesium3DTileContent.prototype.hasProperty = function (batchId, name) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Returns the {@link Cesium3DTileFeature} object for the feature with the
   * given <code>batchId</code>.  This object is used to get and modify the
   * feature's properties.
   * <p>
   * Features in a tile are ordered by <code>batchId</code>, an index used to retrieve their metadata from the batch table.
   * </p>
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/BatchTable}.
   *
   * @param {Number} batchId The batchId for the feature.
   * @returns {Cesium3DTileFeature} The corresponding {@link Cesium3DTileFeature} object.
   *
   * @exception {DeveloperError} batchId must be between zero and {@link Cesium3DTileContent#featuresLength} - 1.
   */
  Cesium3DTileContent.prototype.getFeature = function (batchId) {
    DeveloperError.throwInstantiationError();
  };

  /**
       * Called when {@link Cesium3DTileset#debugColorizeTiles} changes.
       * <p>
       * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
       * not part of the public Cesium API.
       * </p>
       *
       * @param {Boolean} enabled Whether to enable or disable debug settings.
       * @returns {Cesium3DTileFeature} The corresponding {@link Cesium3DTileFeature} object.

       * @private
       */
  Cesium3DTileContent.prototype.applyDebugSettings = function (enabled, color) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Apply a style to the content
   * <p>
   * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
   * not part of the public Cesium API.
   * </p>
   *
   * @param {Cesium3DTileStyle} style The style.
   *
   * @private
   */
  Cesium3DTileContent.prototype.applyStyle = function (style) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Called by the tile during tileset traversal to get the draw commands needed to render this content.
   * When the tile's content is in the PROCESSING state, this creates WebGL resources to ultimately
   * move to the READY state.
   * <p>
   * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
   * not part of the public Cesium API.
   * </p>
   *
   * @param {Cesium3DTileset} tileset The tileset containing this tile.
   * @param {FrameState} frameState The frame state.
   *
   * @private
   */
  Cesium3DTileContent.prototype.update = function (tileset, frameState) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * <p>
   * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
   * not part of the public Cesium API.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Cesium3DTileContent#destroy
   *
   * @private
   */
  Cesium3DTileContent.prototype.isDestroyed = function () {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * <p>
   * This is used to implement the <code>Cesium3DTileContent</code> interface, but is
   * not part of the public Cesium API.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * content = content && content.destroy();
   *
   * @see Cesium3DTileContent#isDestroyed
   *
   * @private
   */
  Cesium3DTileContent.prototype.destroy = function () {
    DeveloperError.throwInstantiationError();
  };

  /**
   * The state for a 3D Tiles update pass.
   *
   * @private
   * @constructor
   */
  function Cesium3DTilePassState(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.number("options.pass", options.pass);
    //>>includeEnd('debug');

    /**
     * The pass.
     *
     * @type {Cesium3DTilePass}
     */
    this.pass = options.pass;

    /**
     * An array of rendering commands to use instead of {@link FrameState.commandList} for the current pass.
     *
     * @type {DrawCommand[]}
     */
    this.commandList = options.commandList;

    /**
     * A camera to use instead of {@link FrameState.camera} for the current pass.
     *
     * @type {Camera}
     */
    this.camera = options.camera;

    /**
     * A culling volume to use instead of {@link FrameState.cullingVolume} for the current pass.
     *
     * @type {CullingVolume}
     */
    this.cullingVolume = options.cullingVolume;

    /**
     * A read-only property that indicates whether the pass is ready, i.e. all tiles needed by the pass are loaded.
     *
     * @type {Boolean}
     * @readonly
     * @default false
     */
    this.ready = false;
  }

  /**
   * An expression for a style applied to a {@link Cesium3DTileset}.
   * <p>
   * Evaluates a conditions expression defined using the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}.
   * </p>
   * <p>
   * Implements the {@link StyleExpression} interface.
   * </p>
   *
   * @alias ConditionsExpression
   * @constructor
   *
   * @param {Object} [conditionsExpression] The conditions expression defined using the 3D Tiles Styling language.
   * @param {Object} [defines] Defines in the style.
   *
   * @example
   * var expression = new Cesium.ConditionsExpression({
   *     conditions : [
   *         ['${Area} > 10, 'color("#FF0000")'],
   *         ['${id} !== "1"', 'color("#00FF00")'],
   *         ['true', 'color("#FFFFFF")']
   *     ]
   * });
   * expression.evaluateColor(feature, result); // returns a Cesium.Color object
   */
  function ConditionsExpression(conditionsExpression, defines) {
    this._conditionsExpression = clone(conditionsExpression, true);
    this._conditions = conditionsExpression.conditions;
    this._runtimeConditions = undefined;

    setRuntime(this, defines);
  }

  Object.defineProperties(ConditionsExpression.prototype, {
    /**
     * Gets the conditions expression defined in the 3D Tiles Styling language.
     *
     * @memberof ConditionsExpression.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @default undefined
     */
    conditionsExpression: {
      get: function () {
        return this._conditionsExpression;
      },
    },
  });

  function Statement(condition, expression) {
    this.condition = condition;
    this.expression = expression;
  }

  function setRuntime(expression, defines) {
    var runtimeConditions = [];
    var conditions = expression._conditions;
    if (!defined(conditions)) {
      return;
    }
    var length = conditions.length;
    for (var i = 0; i < length; ++i) {
      var statement = conditions[i];
      var cond = String(statement[0]);
      var condExpression = String(statement[1]);
      runtimeConditions.push(
        new Statement(
          new Expression(cond, defines),
          new Expression(condExpression, defines)
        )
      );
    }
    expression._runtimeConditions = runtimeConditions;
  }

  /**
   * Evaluates the result of an expression, optionally using the provided feature's properties. If the result of
   * the expression in the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
   * is of type <code>Boolean</code>, <code>Number</code>, or <code>String</code>, the corresponding JavaScript
   * primitive type will be returned. If the result is a <code>RegExp</code>, a Javascript <code>RegExp</code>
   * object will be returned. If the result is a <code>Cartesian2</code>, <code>Cartesian3</code>, or <code>Cartesian4</code>,
   * a {@link Cartesian2}, {@link Cartesian3}, or {@link Cartesian4} object will be returned. If the <code>result</code> argument is
   * a {@link Color}, the {@link Cartesian4} value is converted to a {@link Color} and then returned.
   *
   * @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
   * @param {Object} [result] The object onto which to store the result.
   * @returns {Boolean|Number|String|RegExp|Cartesian2|Cartesian3|Cartesian4|Color} The result of evaluating the expression.
   */
  ConditionsExpression.prototype.evaluate = function (feature, result) {
    var conditions = this._runtimeConditions;
    if (!defined(conditions)) {
      return undefined;
    }
    var length = conditions.length;
    for (var i = 0; i < length; ++i) {
      var statement = conditions[i];
      if (statement.condition.evaluate(feature)) {
        return statement.expression.evaluate(feature, result);
      }
    }
  };

  /**
   * Evaluates the result of a Color expression, using the values defined by a feature.
   * <p>
   * This is equivalent to {@link ConditionsExpression#evaluate} but always returns a {@link Color} object.
   * </p>
   * @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
   * @param {Color} [result] The object in which to store the result
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   */
  ConditionsExpression.prototype.evaluateColor = function (feature, result) {
    var conditions = this._runtimeConditions;
    if (!defined(conditions)) {
      return undefined;
    }
    var length = conditions.length;
    for (var i = 0; i < length; ++i) {
      var statement = conditions[i];
      if (statement.condition.evaluate(feature)) {
        return statement.expression.evaluateColor(feature, result);
      }
    }
  };

  /**
   * Gets the shader function for this expression.
   * Returns undefined if the shader function can't be generated from this expression.
   *
   * @param {String} functionName Name to give to the generated function.
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   * @param {String} returnType The return type of the generated function.
   *
   * @returns {String} The shader function.
   *
   * @private
   */
  ConditionsExpression.prototype.getShaderFunction = function (
    functionName,
    propertyNameMap,
    shaderState,
    returnType
  ) {
    var conditions = this._runtimeConditions;
    if (!defined(conditions) || conditions.length === 0) {
      return undefined;
    }

    var shaderFunction = "";
    var length = conditions.length;
    for (var i = 0; i < length; ++i) {
      var statement = conditions[i];

      var condition = statement.condition.getShaderExpression(
        propertyNameMap,
        shaderState
      );
      var expression = statement.expression.getShaderExpression(
        propertyNameMap,
        shaderState
      );

      // Build the if/else chain from the list of conditions
      shaderFunction +=
        "    " +
        (i === 0 ? "if" : "else if") +
        " (" +
        condition +
        ") \n" +
        "    { \n" +
        "        return " +
        expression +
        "; \n" +
        "    } \n";
    }

    shaderFunction =
      returnType +
      " " +
      functionName +
      "() \n" +
      "{ \n" +
      shaderFunction +
      "    return " +
      returnType +
      "(1.0); \n" + // Return a default value if no conditions are met
      "} \n";

    return shaderFunction;
  };

  /**
   * A style that is applied to a {@link Cesium3DTileset}.
   * <p>
   * Evaluates an expression defined using the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}.
   * </p>
   *
   * @alias Cesium3DTileStyle
   * @constructor
   *
   * @param {Resource|String|Object} [style] The url of a style or an object defining a style.
   *
   * @example
   * tileset.style = new Cesium.Cesium3DTileStyle({
   *     color : {
   *         conditions : [
   *             ['${Height} >= 100', 'color("purple", 0.5)'],
   *             ['${Height} >= 50', 'color("red")'],
   *             ['true', 'color("blue")']
   *         ]
   *     },
   *     show : '${Height} > 0',
   *     meta : {
   *         description : '"Building id ${id} has height ${Height}."'
   *     }
   * });
   *
   * @example
   * tileset.style = new Cesium.Cesium3DTileStyle({
   *     color : 'vec4(${Temperature})',
   *     pointSize : '${Temperature} * 2.0'
   * });
   *
   * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
   */
  function Cesium3DTileStyle(style) {
    this._style = {};
    this._ready = false;

    this._show = undefined;
    this._color = undefined;
    this._pointSize = undefined;
    this._pointOutlineColor = undefined;
    this._pointOutlineWidth = undefined;
    this._labelColor = undefined;
    this._labelOutlineColor = undefined;
    this._labelOutlineWidth = undefined;
    this._font = undefined;
    this._labelStyle = undefined;
    this._labelText = undefined;
    this._backgroundColor = undefined;
    this._backgroundPadding = undefined;
    this._backgroundEnabled = undefined;
    this._scaleByDistance = undefined;
    this._translucencyByDistance = undefined;
    this._distanceDisplayCondition = undefined;
    this._heightOffset = undefined;
    this._anchorLineEnabled = undefined;
    this._anchorLineColor = undefined;
    this._image = undefined;
    this._disableDepthTestDistance = undefined;
    this._horizontalOrigin = undefined;
    this._verticalOrigin = undefined;
    this._labelHorizontalOrigin = undefined;
    this._labelVerticalOrigin = undefined;
    this._meta = undefined;

    this._colorShaderFunction = undefined;
    this._showShaderFunction = undefined;
    this._pointSizeShaderFunction = undefined;
    this._colorShaderFunctionReady = false;
    this._showShaderFunctionReady = false;
    this._pointSizeShaderFunctionReady = false;

    this._colorShaderTranslucent = false;

    var promise;
    if (typeof style === "string" || style instanceof Resource) {
      var resource = Resource.createIfNeeded(style);
      promise = resource.fetchJson(style);
    } else {
      promise = when.resolve(style);
    }

    var that = this;
    this._readyPromise = promise.then(function (styleJson) {
      setup(that, styleJson);
      return that;
    });
  }

  function setup(that, styleJson) {
    styleJson = defaultValue(clone(styleJson, true), that._style);
    that._style = styleJson;

    that.show = styleJson.show;
    that.color = styleJson.color;
    that.pointSize = styleJson.pointSize;
    that.pointOutlineColor = styleJson.pointOutlineColor;
    that.pointOutlineWidth = styleJson.pointOutlineWidth;
    that.labelColor = styleJson.labelColor;
    that.labelOutlineColor = styleJson.labelOutlineColor;
    that.labelOutlineWidth = styleJson.labelOutlineWidth;
    that.labelStyle = styleJson.labelStyle;
    that.font = styleJson.font;
    that.labelText = styleJson.labelText;
    that.backgroundColor = styleJson.backgroundColor;
    that.backgroundPadding = styleJson.backgroundPadding;
    that.backgroundEnabled = styleJson.backgroundEnabled;
    that.scaleByDistance = styleJson.scaleByDistance;
    that.translucencyByDistance = styleJson.translucencyByDistance;
    that.distanceDisplayCondition = styleJson.distanceDisplayCondition;
    that.heightOffset = styleJson.heightOffset;
    that.anchorLineEnabled = styleJson.anchorLineEnabled;
    that.anchorLineColor = styleJson.anchorLineColor;
    that.image = styleJson.image;
    that.disableDepthTestDistance = styleJson.disableDepthTestDistance;
    that.horizontalOrigin = styleJson.horizontalOrigin;
    that.verticalOrigin = styleJson.verticalOrigin;
    that.labelHorizontalOrigin = styleJson.labelHorizontalOrigin;
    that.labelVerticalOrigin = styleJson.labelVerticalOrigin;

    var meta = {};
    if (defined(styleJson.meta)) {
      var defines = styleJson.defines;
      var metaJson = defaultValue(styleJson.meta, defaultValue.EMPTY_OBJECT);
      for (var property in metaJson) {
        if (metaJson.hasOwnProperty(property)) {
          meta[property] = new Expression(metaJson[property], defines);
        }
      }
    }

    that._meta = meta;

    that._ready = true;
  }

  function getExpression(tileStyle, value) {
    var defines = defaultValue(tileStyle._style, defaultValue.EMPTY_OBJECT)
      .defines;

    if (!defined(value)) {
      return undefined;
    } else if (typeof value === "boolean" || typeof value === "number") {
      return new Expression(String(value));
    } else if (typeof value === "string") {
      return new Expression(value, defines);
    } else if (defined(value.conditions)) {
      return new ConditionsExpression(value, defines);
    }
    return value;
  }

  function getJsonFromExpression(expression) {
    if (!defined(expression)) {
      return undefined;
    } else if (defined(expression.expression)) {
      return expression.expression;
    } else if (defined(expression.conditionsExpression)) {
      return clone(expression.conditionsExpression, true);
    }
    return expression;
  }

  Object.defineProperties(Cesium3DTileStyle.prototype, {
    /**
     * Gets the object defining the style using the
     * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}.
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @default {}
     *
     * @exception {DeveloperError} The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true.
     */
    style: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._style;
      },
    },

    /**
     * When <code>true</code>, the style is ready and its expressions can be evaluated.  When
     * a style is constructed with an object, as opposed to a url, this is <code>true</code> immediately.
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets the promise that will be resolved when the the style is ready and its expressions can be evaluated.
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {Promise.<Cesium3DTileStyle>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>show</code> property. Alternatively a boolean, string, or object defining a show style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return or convert to a <code>Boolean</code>.
     * </p>
     * <p>
     * This expression is applicable to all tile formats.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     show : '(regExp("^Chest").test(${County})) && (${YearBuilt} >= 1970)'
     * });
     * style.show.evaluate(feature); // returns true or false depending on the feature's properties
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override show expression with a custom function
     * style.show = {
     *     evaluate : function(feature) {
     *         return true;
     *     }
     * };
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override show expression with a boolean
     * style.show = true;
     * };
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override show expression with a string
     * style.show = '${Height} > 0';
     * };
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override show expression with a condition
     * style.show = {
     *     conditions: [
     *         ['${height} > 2', 'false'],
     *         ['true', 'true']
     *     ];
     * };
     */
    show: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._show;
      },
      set: function (value) {
        this._show = getExpression(this, value);
        this._style.show = getJsonFromExpression(this._show);
        this._showShaderFunctionReady = false;
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>color</code> property. Alternatively a string or object defining a color style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Color</code>.
     * </p>
     * <p>
     * This expression is applicable to all tile formats.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     color : '(${Temperature} > 90) ? color("red") : color("white")'
     * });
     * style.color.evaluateColor(feature, result); // returns a Cesium.Color object
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override color expression with a custom function
     * style.color = {
     *     evaluateColor : function(feature, result) {
     *         return Cesium.Color.clone(Cesium.Color.WHITE, result);
     *     }
     * };
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override color expression with a string
     * style.color = 'color("blue")';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override color expression with a condition
     * style.color = {
     *     conditions : [
     *         ['${height} > 2', 'color("cyan")'],
     *         ['true', 'color("blue")']
     *     ]
     * };
     */
    color: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._color;
      },
      set: function (value) {
        this._color = getExpression(this, value);
        this._style.color = getJsonFromExpression(this._color);
        this._colorShaderFunctionReady = false;
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>pointSize</code> property. Alternatively a string or object defining a point size style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Number</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile or a Point Cloud tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     pointSize : '(${Temperature} > 90) ? 2.0 : 1.0'
     * });
     * style.pointSize.evaluate(feature); // returns a Number
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointSize expression with a custom function
     * style.pointSize = {
     *     evaluate : function(feature) {
     *         return 1.0;
     *     }
     * };
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointSize expression with a number
     * style.pointSize = 1.0;
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointSize expression with a string
     * style.pointSize = '${height} / 10';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointSize expression with a condition
     * style.pointSize =  {
     *     conditions : [
     *         ['${height} > 2', '1.0'],
     *         ['true', '2.0']
     *     ]
     * };
     */
    pointSize: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._pointSize;
      },
      set: function (value) {
        this._pointSize = getExpression(this, value);
        this._style.pointSize = getJsonFromExpression(this._pointSize);
        this._pointSizeShaderFunctionReady = false;
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>pointOutlineColor</code> property. Alternatively a string or object defining a color style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Color</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointOutlineColor expression with a string
     * style.pointOutlineColor = 'color("blue")';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointOutlineColor expression with a condition
     * style.pointOutlineColor = {
     *     conditions : [
     *         ['${height} > 2', 'color("cyan")'],
     *         ['true', 'color("blue")']
     *     ]
     * };
     */
    pointOutlineColor: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._pointOutlineColor;
      },
      set: function (value) {
        this._pointOutlineColor = getExpression(this, value);
        this._style.pointOutlineColor = getJsonFromExpression(
          this._pointOutlineColor
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>pointOutlineWidth</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Number</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointOutlineWidth expression with a string
     * style.pointOutlineWidth = '5';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override pointOutlineWidth expression with a condition
     * style.pointOutlineWidth = {
     *     conditions : [
     *         ['${height} > 2', '5'],
     *         ['true', '0']
     *     ]
     * };
     */
    pointOutlineWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._pointOutlineWidth;
      },
      set: function (value) {
        this._pointOutlineWidth = getExpression(this, value);
        this._style.pointOutlineWidth = getJsonFromExpression(
          this._pointOutlineWidth
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>labelColor</code> property. Alternatively a string or object defining a color style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Color</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelColor expression with a string
     * style.labelColor = 'color("blue")';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelColor expression with a condition
     * style.labelColor = {
     *     conditions : [
     *         ['${height} > 2', 'color("cyan")'],
     *         ['true', 'color("blue")']
     *     ]
     * };
     */
    labelColor: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelColor;
      },
      set: function (value) {
        this._labelColor = getExpression(this, value);
        this._style.labelColor = getJsonFromExpression(this._labelColor);
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>labelOutlineColor</code> property. Alternatively a string or object defining a color style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Color</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelOutlineColor expression with a string
     * style.labelOutlineColor = 'color("blue")';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelOutlineColor expression with a condition
     * style.labelOutlineColor = {
     *     conditions : [
     *         ['${height} > 2', 'color("cyan")'],
     *         ['true', 'color("blue")']
     *     ]
     * };
     */
    labelOutlineColor: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelOutlineColor;
      },
      set: function (value) {
        this._labelOutlineColor = getExpression(this, value);
        this._style.labelOutlineColor = getJsonFromExpression(
          this._labelOutlineColor
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>labelOutlineWidth</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Number</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelOutlineWidth expression with a string
     * style.labelOutlineWidth = '5';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelOutlineWidth expression with a condition
     * style.labelOutlineWidth = {
     *     conditions : [
     *         ['${height} > 2', '5'],
     *         ['true', '0']
     *     ]
     * };
     */
    labelOutlineWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelOutlineWidth;
      },
      set: function (value) {
        this._labelOutlineWidth = getExpression(this, value);
        this._style.labelOutlineWidth = getJsonFromExpression(
          this._labelOutlineWidth
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>font</code> property. Alternatively a string or object defining a string style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>String</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     font : '(${Temperature} > 90) ? "30px Helvetica" : "24px Helvetica"'
     * });
     * style.font.evaluate(feature); // returns a String
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override font expression with a custom function
     * style.font = {
     *     evaluate : function(feature) {
     *         return '24px Helvetica';
     *     }
     * };
     */
    font: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._font;
      },
      set: function (value) {
        this._font = getExpression(this, value);
        this._style.font = getJsonFromExpression(this._font);
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>label style</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>LabelStyle</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     labelStyle : '(${Temperature} > 90) ? ' + LabelStyle.FILL_AND_OUTLINE + ' : ' + LabelStyle.FILL
     * });
     * style.labelStyle.evaluate(feature); // returns a LabelStyle
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelStyle expression with a custom function
     * style.labelStyle = {
     *     evaluate : function(feature) {
     *         return LabelStyle.FILL;
     *     }
     * };
     */
    labelStyle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelStyle;
      },
      set: function (value) {
        this._labelStyle = getExpression(this, value);
        this._style.labelStyle = getJsonFromExpression(this._labelStyle);
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>labelText</code> property. Alternatively a string or object defining a string style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>String</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     labelText : '(${Temperature} > 90) ? ">90" : "<=90"'
     * });
     * style.labelText.evaluate(feature); // returns a String
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelText expression with a custom function
     * style.labelText = {
     *     evaluate : function(feature) {
     *         return 'Example label text';
     *     }
     * };
     */
    labelText: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelText;
      },
      set: function (value) {
        this._labelText = getExpression(this, value);
        this._style.labelText = getJsonFromExpression(this._labelText);
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>backgroundColor</code> property. Alternatively a string or object defining a color style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Color</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override backgroundColor expression with a string
     * style.backgroundColor = 'color("blue")';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override backgroundColor expression with a condition
     * style.backgroundColor = {
     *     conditions : [
     *         ['${height} > 2', 'color("cyan")'],
     *         ['true', 'color("blue")']
     *     ]
     * };
     */
    backgroundColor: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._backgroundColor;
      },
      set: function (value) {
        this._backgroundColor = getExpression(this, value);
        this._style.backgroundColor = getJsonFromExpression(
          this._backgroundColor
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>backgroundPadding</code> property. Alternatively a string or object defining a vec2 style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Cartesian2</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override backgroundPadding expression with a string
     * style.backgroundPadding = 'vec2(5.0, 7.0)';
     * style.backgroundPadding.evaluate(feature); // returns a Cartesian2
     */
    backgroundPadding: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._backgroundPadding;
      },
      set: function (value) {
        this._backgroundPadding = getExpression(this, value);
        this._style.backgroundPadding = getJsonFromExpression(
          this._backgroundPadding
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>backgroundEnabled</code> property. Alternatively a string or object defining a boolean style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Boolean</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override backgroundEnabled expression with a string
     * style.backgroundEnabled = 'true';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override backgroundEnabled expression with a condition
     * style.backgroundEnabled = {
     *     conditions : [
     *         ['${height} > 2', 'true'],
     *         ['true', 'false']
     *     ]
     * };
     */
    backgroundEnabled: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._backgroundEnabled;
      },
      set: function (value) {
        this._backgroundEnabled = getExpression(this, value);
        this._style.backgroundEnabled = getJsonFromExpression(
          this._backgroundEnabled
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>scaleByDistance</code> property. Alternatively a string or object defining a vec4 style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Cartesian4</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override scaleByDistance expression with a string
     * style.scaleByDistance = 'vec4(1.5e2, 2.0, 1.5e7, 0.5)';
     * style.scaleByDistance.evaluate(feature); // returns a Cartesian4
     */
    scaleByDistance: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._scaleByDistance;
      },
      set: function (value) {
        this._scaleByDistance = getExpression(this, value);
        this._style.scaleByDistance = getJsonFromExpression(
          this._scaleByDistance
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>translucencyByDistance</code> property. Alternatively a string or object defining a vec4 style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Cartesian4</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override translucencyByDistance expression with a string
     * style.translucencyByDistance = 'vec4(1.5e2, 1.0, 1.5e7, 0.2)';
     * style.translucencyByDistance.evaluate(feature); // returns a Cartesian4
     */
    translucencyByDistance: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._translucencyByDistance;
      },
      set: function (value) {
        this._translucencyByDistance = getExpression(this, value);
        this._style.translucencyByDistance = getJsonFromExpression(
          this._translucencyByDistance
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>distanceDisplayCondition</code> property. Alternatively a string or object defining a vec2 style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Cartesian2</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override distanceDisplayCondition expression with a string
     * style.distanceDisplayCondition = 'vec2(0.0, 5.5e6)';
     * style.distanceDisplayCondition.evaluate(feature); // returns a Cartesian2
     */
    distanceDisplayCondition: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._distanceDisplayCondition;
      },
      set: function (value) {
        this._distanceDisplayCondition = getExpression(this, value);
        this._style.distanceDisplayCondition = getJsonFromExpression(
          this._distanceDisplayCondition
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>heightOffset</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Number</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override heightOffset expression with a string
     * style.heightOffset = '2.0';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override heightOffset expression with a condition
     * style.heightOffset = {
     *     conditions : [
     *         ['${height} > 2', '4.0'],
     *         ['true', '2.0']
     *     ]
     * };
     */
    heightOffset: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._heightOffset;
      },
      set: function (value) {
        this._heightOffset = getExpression(this, value);
        this._style.heightOffset = getJsonFromExpression(this._heightOffset);
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>anchorLineEnabled</code> property. Alternatively a string or object defining a boolean style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Boolean</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override anchorLineEnabled expression with a string
     * style.anchorLineEnabled = 'true';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override anchorLineEnabled expression with a condition
     * style.anchorLineEnabled = {
     *     conditions : [
     *         ['${height} > 2', 'true'],
     *         ['true', 'false']
     *     ]
     * };
     */
    anchorLineEnabled: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._anchorLineEnabled;
      },
      set: function (value) {
        this._anchorLineEnabled = getExpression(this, value);
        this._style.anchorLineEnabled = getJsonFromExpression(
          this._anchorLineEnabled
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>anchorLineColor</code> property. Alternatively a string or object defining a color style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Color</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override anchorLineColor expression with a string
     * style.anchorLineColor = 'color("blue")';
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override anchorLineColor expression with a condition
     * style.anchorLineColor = {
     *     conditions : [
     *         ['${height} > 2', 'color("cyan")'],
     *         ['true', 'color("blue")']
     *     ]
     * };
     */
    anchorLineColor: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._anchorLineColor;
      },
      set: function (value) {
        this._anchorLineColor = getExpression(this, value);
        this._style.anchorLineColor = getJsonFromExpression(
          this._anchorLineColor
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>image</code> property. Alternatively a string or object defining a string style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>String</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     image : '(${Temperature} > 90) ? "/url/to/image1" : "/url/to/image2"'
     * });
     * style.image.evaluate(feature); // returns a String
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override image expression with a custom function
     * style.image = {
     *     evaluate : function(feature) {
     *         return '/url/to/image';
     *     }
     * };
     */
    image: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._image;
      },
      set: function (value) {
        this._image = getExpression(this, value);
        this._style.image = getJsonFromExpression(this._image);
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>disableDepthTestDistance</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>Number</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override disableDepthTestDistance expression with a string
     * style.disableDepthTestDistance = '1000.0';
     * style.disableDepthTestDistance.evaluate(feature); // returns a Number
     */
    disableDepthTestDistance: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._disableDepthTestDistance;
      },
      set: function (value) {
        this._disableDepthTestDistance = getExpression(this, value);
        this._style.disableDepthTestDistance = getJsonFromExpression(
          this._disableDepthTestDistance
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>horizontalOrigin</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>HorizontalOrigin</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     horizontalOrigin : HorizontalOrigin.LEFT
     * });
     * style.horizontalOrigin.evaluate(feature); // returns a HorizontalOrigin
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override horizontalOrigin expression with a custom function
     * style.horizontalOrigin = {
     *     evaluate : function(feature) {
     *         return HorizontalOrigin.CENTER;
     *     }
     * };
     */
    horizontalOrigin: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._horizontalOrigin;
      },
      set: function (value) {
        this._horizontalOrigin = getExpression(this, value);
        this._style.horizontalOrigin = getJsonFromExpression(
          this._horizontalOrigin
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>verticalOrigin</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>VerticalOrigin</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     verticalOrigin : VerticalOrigin.TOP
     * });
     * style.verticalOrigin.evaluate(feature); // returns a VerticalOrigin
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override verticalOrigin expression with a custom function
     * style.verticalOrigin = {
     *     evaluate : function(feature) {
     *         return VerticalOrigin.CENTER;
     *     }
     * };
     */
    verticalOrigin: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._verticalOrigin;
      },
      set: function (value) {
        this._verticalOrigin = getExpression(this, value);
        this._style.verticalOrigin = getJsonFromExpression(this._verticalOrigin);
      },
    },

    /**
           Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>labelHorizontalOrigin</code> property. Alternatively a string or object defining a number style can be used.
           * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
           * <p>
           * The expression must return a <code>HorizontalOrigin</code>.
           * </p>
           * <p>
           * This expression is only applicable to point features in a Vector tile.
           * </p>
           *
           * @memberof Cesium3DTileStyle.prototype
           *
           * @type {StyleExpression}
           *
           * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
           *
           * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
           *
           * @example
           * var style = new Cesium3DTileStyle({
           *     labelHorizontalOrigin : HorizontalOrigin.LEFT
           * });
           * style.labelHorizontalOrigin.evaluate(feature); // returns a HorizontalOrigin
           *
           * @example
           * var style = new Cesium.Cesium3DTileStyle();
           * // Override labelHorizontalOrigin expression with a custom function
           * style.labelHorizontalOrigin = {
           *     evaluate : function(feature) {
           *         return HorizontalOrigin.CENTER;
           *     }
           * };
           */
    labelHorizontalOrigin: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelHorizontalOrigin;
      },
      set: function (value) {
        this._labelHorizontalOrigin = getExpression(this, value);
        this._style.labelHorizontalOrigin = getJsonFromExpression(
          this._labelHorizontalOrigin
        );
      },
    },

    /**
     * Gets or sets the {@link StyleExpression} object used to evaluate the style's <code>labelVerticalOrigin</code> property. Alternatively a string or object defining a number style can be used.
     * The getter will return the internal {@link Expression} or {@link ConditionsExpression}, which may differ from the value provided to the setter.
     * <p>
     * The expression must return a <code>VerticalOrigin</code>.
     * </p>
     * <p>
     * This expression is only applicable to point features in a Vector tile.
     * </p>
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     labelVerticalOrigin : VerticalOrigin.TOP
     * });
     * style.labelVerticalOrigin.evaluate(feature); // returns a VerticalOrigin
     *
     * @example
     * var style = new Cesium.Cesium3DTileStyle();
     * // Override labelVerticalOrigin expression with a custom function
     * style.labelVerticalOrigin = {
     *     evaluate : function(feature) {
     *         return VerticalOrigin.CENTER;
     *     }
     * };
     */
    labelVerticalOrigin: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._labelVerticalOrigin;
      },
      set: function (value) {
        this._labelVerticalOrigin = getExpression(this, value);
        this._style.labelVerticalOrigin = getJsonFromExpression(
          this._labelVerticalOrigin
        );
      },
    },

    /**
     * Gets or sets the object containing application-specific expression that can be explicitly
     * evaluated, e.g., for display in a UI.
     *
     * @memberof Cesium3DTileStyle.prototype
     *
     * @type {StyleExpression}
     *
     * @exception {DeveloperError} The style is not loaded.  Use {@link Cesium3DTileStyle#readyPromise} or wait for {@link Cesium3DTileStyle#ready} to be true.
     *
     * @example
     * var style = new Cesium3DTileStyle({
     *     meta : {
     *         description : '"Building id ${id} has height ${Height}."'
     *     }
     * });
     * style.meta.description.evaluate(feature); // returns a String with the substituted variables
     */
    meta: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "The style is not loaded.  Use Cesium3DTileStyle.readyPromise or wait for Cesium3DTileStyle.ready to be true."
          );
        }
        //>>includeEnd('debug');

        return this._meta;
      },
      set: function (value) {
        this._meta = value;
      },
    },
  });

  /**
   * Gets the color shader function for this style.
   *
   * @param {String} functionName Name to give to the generated function.
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   *
   * @returns {String} The shader function.
   *
   * @private
   */
  Cesium3DTileStyle.prototype.getColorShaderFunction = function (
    functionName,
    propertyNameMap,
    shaderState
  ) {
    if (this._colorShaderFunctionReady) {
      shaderState.translucent = this._colorShaderTranslucent;
      // Return the cached result, may be undefined
      return this._colorShaderFunction;
    }

    this._colorShaderFunctionReady = true;
    this._colorShaderFunction = defined(this.color)
      ? this.color.getShaderFunction(
          functionName,
          propertyNameMap,
          shaderState,
          "vec4"
        )
      : undefined;
    this._colorShaderTranslucent = shaderState.translucent;
    return this._colorShaderFunction;
  };

  /**
   * Gets the show shader function for this style.
   *
   * @param {String} functionName Name to give to the generated function.
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   *
   * @returns {String} The shader function.
   *
   * @private
   */
  Cesium3DTileStyle.prototype.getShowShaderFunction = function (
    functionName,
    propertyNameMap,
    shaderState
  ) {
    if (this._showShaderFunctionReady) {
      // Return the cached result, may be undefined
      return this._showShaderFunction;
    }

    this._showShaderFunctionReady = true;
    this._showShaderFunction = defined(this.show)
      ? this.show.getShaderFunction(
          functionName,
          propertyNameMap,
          shaderState,
          "bool"
        )
      : undefined;
    return this._showShaderFunction;
  };

  /**
   * Gets the pointSize shader function for this style.
   *
   * @param {String} functionName Name to give to the generated function.
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   *
   * @returns {String} The shader function.
   *
   * @private
   */
  Cesium3DTileStyle.prototype.getPointSizeShaderFunction = function (
    functionName,
    propertyNameMap,
    shaderState
  ) {
    if (this._pointSizeShaderFunctionReady) {
      // Return the cached result, may be undefined
      return this._pointSizeShaderFunction;
    }

    this._pointSizeShaderFunctionReady = true;
    this._pointSizeShaderFunction = defined(this.pointSize)
      ? this.pointSize.getShaderFunction(
          functionName,
          propertyNameMap,
          shaderState,
          "float"
        )
      : undefined;
    return this._pointSizeShaderFunction;
  };

  /**
   * A ParticleEmitter that emits particles from a circle.
   * Particles will be positioned within a circle and have initial velocities going along the z vector.
   *
   * @alias CircleEmitter
   * @constructor
   *
   * @param {Number} [radius=1.0] The radius of the circle in meters.
   */
  function CircleEmitter(radius) {
    radius = defaultValue(radius, 1.0);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThan("radius", radius, 0.0);
    //>>includeEnd('debug');

    this._radius = defaultValue(radius, 1.0);
  }

  Object.defineProperties(CircleEmitter.prototype, {
    /**
     * The radius of the circle in meters.
     * @memberof CircleEmitter.prototype
     * @type {Number}
     * @default 1.0
     */
    radius: {
      get: function () {
        return this._radius;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThan("value", value, 0.0);
        //>>includeEnd('debug');
        this._radius = value;
      },
    },
  });

  /**
   * Initializes the given {@link Particle} by setting it's position and velocity.
   *
   * @private
   * @param {Particle} particle The particle to initialize.
   */
  CircleEmitter.prototype.emit = function (particle) {
    var theta = CesiumMath.randomBetween(0.0, CesiumMath.TWO_PI);
    var rad = CesiumMath.randomBetween(0.0, this._radius);

    var x = rad * Math.cos(theta);
    var y = rad * Math.sin(theta);
    var z = 0.0;

    particle.position = Cartesian3.fromElements(x, y, z, particle.position);
    particle.velocity = Cartesian3.clone(Cartesian3.UNIT_Z, particle.velocity);
  };

  var defaultAngle = CesiumMath.toRadians(30.0);

  /**
   * A ParticleEmitter that emits particles within a cone.
   * Particles will be positioned at the tip of the cone and have initial velocities going towards the base.
   *
   * @alias ConeEmitter
   * @constructor
   *
   * @param {Number} [angle=Cesium.Math.toRadians(30.0)] The angle of the cone in radians.
   */
  function ConeEmitter(angle) {
    this._angle = defaultValue(angle, defaultAngle);
  }

  Object.defineProperties(ConeEmitter.prototype, {
    /**
     * The angle of the cone in radians.
     * @memberof CircleEmitter.prototype
     * @type {Number}
     * @default Cesium.Math.toRadians(30.0)
     */
    angle: {
      get: function () {
        return this._angle;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number("value", value);
        //>>includeEnd('debug');
        this._angle = value;
      },
    },
  });

  /**
   * Initializes the given {Particle} by setting it's position and velocity.
   *
   * @private
   * @param {Particle} particle The particle to initialize
   */
  ConeEmitter.prototype.emit = function (particle) {
    var radius = Math.tan(this._angle);

    // Compute a random point on the cone's base
    var theta = CesiumMath.randomBetween(0.0, CesiumMath.TWO_PI);
    var rad = CesiumMath.randomBetween(0.0, radius);

    var x = rad * Math.cos(theta);
    var y = rad * Math.sin(theta);
    var z = 1.0;

    particle.velocity = Cartesian3.fromElements(x, y, z, particle.velocity);
    Cartesian3.normalize(particle.velocity, particle.velocity);
    particle.position = Cartesian3.clone(Cartesian3.ZERO, particle.position);
  };

  var mobileWidth = 576;
  var lightboxHeight = 100;
  var textColor = "#ffffff";
  var highlightColor = "#48b";

  function contains$1(credits, credit) {
    var len = credits.length;
    for (var i = 0; i < len; i++) {
      var existingCredit = credits[i];
      if (Credit.equals(existingCredit, credit)) {
        return true;
      }
    }
    return false;
  }

  function swapCesiumCredit(creditDisplay) {
    // We don't want to clutter the screen with the Cesium logo and the Cesium ion
    // logo at the same time. Since the ion logo is required, we just replace the
    // Cesium logo or add the logo if the Cesium one was removed.
    var previousCredit = creditDisplay._previousCesiumCredit;
    var currentCredit = creditDisplay._currentCesiumCredit;
    if (Credit.equals(currentCredit, previousCredit)) {
      return;
    }

    if (defined(previousCredit)) {
      creditDisplay._cesiumCreditContainer.removeChild(previousCredit.element);
    }
    if (defined(currentCredit)) {
      creditDisplay._cesiumCreditContainer.appendChild(currentCredit.element);
    }

    creditDisplay._previousCesiumCredit = currentCredit;
  }

  var delimiterClassName = "cesium-credit-delimiter";

  function createDelimiterElement(delimiter) {
    var delimiterElement = document.createElement("span");
    delimiterElement.textContent = delimiter;
    delimiterElement.className = delimiterClassName;
    return delimiterElement;
  }

  function createCreditElement(element, elementWrapperTagName) {
    // may need to wrap the credit in another element
    if (defined(elementWrapperTagName)) {
      var wrapper = document.createElement(elementWrapperTagName);
      wrapper._creditId = element._creditId;
      wrapper.appendChild(element);
      element = wrapper;
    }
    return element;
  }

  function displayCredits(container, credits, delimiter, elementWrapperTagName) {
    var childNodes = container.childNodes;
    var domIndex = -1;
    for (var creditIndex = 0; creditIndex < credits.length; ++creditIndex) {
      var credit = credits[creditIndex];
      if (defined(credit)) {
        domIndex = creditIndex;
        if (defined(delimiter)) {
          // credits may be separated by delimiters
          domIndex *= 2;
          if (creditIndex > 0) {
            var delimiterDomIndex = domIndex - 1;
            if (childNodes.length <= delimiterDomIndex) {
              container.appendChild(createDelimiterElement(delimiter));
            } else {
              var existingDelimiter = childNodes[delimiterDomIndex];
              if (existingDelimiter.className !== delimiterClassName) {
                container.replaceChild(
                  createDelimiterElement(delimiter),
                  existingDelimiter
                );
              }
            }
          }
        }

        var element = credit.element;

        // check to see if the correct credit is in the right place
        if (childNodes.length <= domIndex) {
          container.appendChild(
            createCreditElement(element, elementWrapperTagName)
          );
        } else {
          var existingElement = childNodes[domIndex];
          if (existingElement._creditId !== credit._id) {
            // not the right credit, swap it in
            container.replaceChild(
              createCreditElement(element, elementWrapperTagName),
              existingElement
            );
          }
        }
      }
    }

    // any remaining nodes in the container are unnecessary
    ++domIndex;
    while (domIndex < childNodes.length) {
      container.removeChild(childNodes[domIndex]);
    }
  }

  function styleLightboxContainer(that) {
    var lightboxCredits = that._lightboxCredits;
    var width = that.viewport.clientWidth;
    var height = that.viewport.clientHeight;
    if (width !== that._lastViewportWidth) {
      if (width < mobileWidth) {
        lightboxCredits.className =
          "cesium-credit-lightbox cesium-credit-lightbox-mobile";
        lightboxCredits.style.marginTop = "0";
      } else {
        lightboxCredits.className =
          "cesium-credit-lightbox cesium-credit-lightbox-expanded";
        lightboxCredits.style.marginTop =
          Math.floor((height - lightboxCredits.clientHeight) * 0.5) + "px";
      }
      that._lastViewportWidth = width;
    }

    if (width >= mobileWidth && height !== that._lastViewportHeight) {
      lightboxCredits.style.marginTop =
        Math.floor((height - lightboxCredits.clientHeight) * 0.5) + "px";
      that._lastViewportHeight = height;
    }
  }

  function addStyle(selector, styles) {
    var style = selector + " {";
    for (var attribute in styles) {
      if (styles.hasOwnProperty(attribute)) {
        style += attribute + ": " + styles[attribute] + "; ";
      }
    }
    style += " }\n";
    return style;
  }

  function appendCss() {
    var style = "";
    style += addStyle(".cesium-credit-lightbox-overlay", {
      display: "none",
      "z-index": "1", //must be at least 1 to draw over top other Cesium widgets
      position: "absolute",
      top: "0",
      left: "0",
      width: "100%",
      height: "100%",
      "background-color": "rgba(80, 80, 80, 0.8)",
    });

    style += addStyle(".cesium-credit-lightbox", {
      "background-color": "#303336",
      color: textColor,
      position: "relative",
      "min-height": lightboxHeight + "px",
      margin: "auto",
    });

    style += addStyle(
      ".cesium-credit-lightbox > ul > li a, .cesium-credit-lightbox > ul > li a:visited",
      {
        color: textColor,
      }
    );

    style += addStyle(".cesium-credit-lightbox > ul > li a:hover", {
      color: highlightColor,
    });

    style += addStyle(".cesium-credit-lightbox.cesium-credit-lightbox-expanded", {
      border: "1px solid #444",
      "border-radius": "5px",
      "max-width": "370px",
    });

    style += addStyle(".cesium-credit-lightbox.cesium-credit-lightbox-mobile", {
      height: "100%",
      width: "100%",
    });

    style += addStyle(".cesium-credit-lightbox-title", {
      padding: "20px 20px 0 20px",
    });

    style += addStyle(".cesium-credit-lightbox-close", {
      "font-size": "18pt",
      cursor: "pointer",
      position: "absolute",
      top: "0",
      right: "6px",
      color: textColor,
    });

    style += addStyle(".cesium-credit-lightbox-close:hover", {
      color: highlightColor,
    });

    style += addStyle(".cesium-credit-lightbox > ul", {
      margin: "0",
      padding: "12px 20px 12px 40px",
      "font-size": "13px",
    });

    style += addStyle(".cesium-credit-lightbox > ul > li", {
      "padding-bottom": "6px",
    });

    style += addStyle(".cesium-credit-lightbox > ul > li *", {
      padding: "0",
      margin: "0",
    });

    style += addStyle(".cesium-credit-expand-link", {
      "padding-left": "5px",
      cursor: "pointer",
      "text-decoration": "underline",
      color: textColor,
    });
    style += addStyle(".cesium-credit-expand-link:hover", {
      color: highlightColor,
    });

    style += addStyle(".cesium-credit-text", {
      color: textColor,
    });

    style += addStyle(
      ".cesium-credit-textContainer *, .cesium-credit-logoContainer *",
      {
        display: "inline",
      }
    );

    var head = document.head;
    var css = document.createElement("style");
    css.innerHTML = style;
    head.insertBefore(css, head.firstChild);
  }

  /**
   * The credit display is responsible for displaying credits on screen.
   *
   * @param {HTMLElement} container The HTML element where credits will be displayed
   * @param {String} [delimiter= ' • '] The string to separate text credits
   * @param {HTMLElement} [viewport=document.body] The HTML element that will contain the credits popup
   *
   * @alias CreditDisplay
   * @constructor
   *
   * @example
   * var creditDisplay = new Cesium.CreditDisplay(creditContainer);
   */
  function CreditDisplay(container, delimiter, viewport) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("container", container);
    //>>includeEnd('debug');
    var that = this;

    viewport = defaultValue(viewport, document.body);

    var lightbox = document.createElement("div");
    lightbox.className = "cesium-credit-lightbox-overlay";
    viewport.appendChild(lightbox);

    var lightboxCredits = document.createElement("div");
    lightboxCredits.className = "cesium-credit-lightbox";
    lightbox.appendChild(lightboxCredits);

    function hideLightbox(event) {
      if (lightboxCredits.contains(event.target)) {
        return;
      }
      that.hideLightbox();
    }
    lightbox.addEventListener("click", hideLightbox, false);

    var title = document.createElement("div");
    title.className = "cesium-credit-lightbox-title";
    title.textContent = "Data provided by:";
    lightboxCredits.appendChild(title);

    var closeButton = document.createElement("a");
    closeButton.onclick = this.hideLightbox.bind(this);
    closeButton.innerHTML = "&times;";
    closeButton.className = "cesium-credit-lightbox-close";
    lightboxCredits.appendChild(closeButton);

    var creditList = document.createElement("ul");
    lightboxCredits.appendChild(creditList);

    var cesiumCreditContainer = document.createElement("div");
    cesiumCreditContainer.className = "cesium-credit-logoContainer";
    cesiumCreditContainer.style.display = "inline";
    container.appendChild(cesiumCreditContainer);

    var screenContainer = document.createElement("div");
    screenContainer.className = "cesium-credit-textContainer";
    screenContainer.style.display = "inline";
    container.appendChild(screenContainer);

    var expandLink = document.createElement("a");
    expandLink.className = "cesium-credit-expand-link";
    expandLink.onclick = this.showLightbox.bind(this);
    expandLink.textContent = "Data attribution";
    container.appendChild(expandLink);

    appendCss();
    var cesiumCredit = Credit.clone(CreditDisplay.cesiumCredit);

    this._delimiter = defaultValue(delimiter, " • ");
    this._screenContainer = screenContainer;
    this._cesiumCreditContainer = cesiumCreditContainer;
    this._lastViewportHeight = undefined;
    this._lastViewportWidth = undefined;
    this._lightboxCredits = lightboxCredits;
    this._creditList = creditList;
    this._lightbox = lightbox;
    this._hideLightbox = hideLightbox;
    this._expandLink = expandLink;
    this._expanded = false;
    this._defaultCredits = [];
    this._cesiumCredit = cesiumCredit;
    this._previousCesiumCredit = undefined;
    this._currentCesiumCredit = cesiumCredit;
    this._currentFrameCredits = {
      screenCredits: new AssociativeArray(),
      lightboxCredits: new AssociativeArray(),
    };
    this._defaultCredit = undefined;

    this.viewport = viewport;

    /**
     * The HTML element where credits will be displayed.
     * @type {HTMLElement}
     */
    this.container = container;
  }

  /**
   * Adds a credit to the list of current credits to be displayed in the credit container
   *
   * @param {Credit} credit The credit to display
   */
  CreditDisplay.prototype.addCredit = function (credit) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("credit", credit);
    //>>includeEnd('debug');

    if (credit._isIon) {
      // If this is the an ion logo credit from the ion server
      // Juse use the default credit (which is identical) to avoid blinking
      if (!defined(this._defaultCredit)) {
        this._defaultCredit = Credit.clone(getDefaultCredit());
      }
      this._currentCesiumCredit = this._defaultCredit;
      return;
    }

    if (!credit.showOnScreen) {
      this._currentFrameCredits.lightboxCredits.set(credit.id, credit);
    } else {
      this._currentFrameCredits.screenCredits.set(credit.id, credit);
    }
  };

  /**
   * Adds credits that will persist until they are removed
   *
   * @param {Credit} credit The credit to added to defaults
   */
  CreditDisplay.prototype.addDefaultCredit = function (credit) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("credit", credit);
    //>>includeEnd('debug');

    var defaultCredits = this._defaultCredits;
    if (!contains$1(defaultCredits, credit)) {
      defaultCredits.push(credit);
    }
  };

  /**
   * Removes a default credit
   *
   * @param {Credit} credit The credit to be removed from defaults
   */
  CreditDisplay.prototype.removeDefaultCredit = function (credit) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("credit", credit);
    //>>includeEnd('debug');

    var defaultCredits = this._defaultCredits;
    var index = defaultCredits.indexOf(credit);
    if (index !== -1) {
      defaultCredits.splice(index, 1);
    }
  };

  CreditDisplay.prototype.showLightbox = function () {
    this._lightbox.style.display = "block";
    this._expanded = true;
  };

  CreditDisplay.prototype.hideLightbox = function () {
    this._lightbox.style.display = "none";
    this._expanded = false;
  };

  /**
   * Updates the credit display before a new frame is rendered.
   */
  CreditDisplay.prototype.update = function () {
    if (this._expanded) {
      styleLightboxContainer(this);
    }
  };

  /**
   * Resets the credit display to a beginning of frame state, clearing out current credits.
   */
  CreditDisplay.prototype.beginFrame = function () {
    var currentFrameCredits = this._currentFrameCredits;

    var screenCredits = currentFrameCredits.screenCredits;
    screenCredits.removeAll();
    var defaultCredits = this._defaultCredits;
    for (var i = 0; i < defaultCredits.length; ++i) {
      var defaultCredit = defaultCredits[i];
      screenCredits.set(defaultCredit.id, defaultCredit);
    }

    currentFrameCredits.lightboxCredits.removeAll();

    if (!Credit.equals(CreditDisplay.cesiumCredit, this._cesiumCredit)) {
      this._cesiumCredit = Credit.clone(CreditDisplay.cesiumCredit);
    }
    this._currentCesiumCredit = this._cesiumCredit;
  };

  /**
   * Sets the credit display to the end of frame state, displaying credits from the last frame in the credit container.
   */
  CreditDisplay.prototype.endFrame = function () {
    var screenCredits = this._currentFrameCredits.screenCredits.values;
    displayCredits(
      this._screenContainer,
      screenCredits,
      this._delimiter,
      undefined
    );

    var lightboxCredits = this._currentFrameCredits.lightboxCredits.values;
    this._expandLink.style.display =
      lightboxCredits.length > 0 ? "inline" : "none";
    displayCredits(this._creditList, lightboxCredits, undefined, "li");

    swapCesiumCredit(this);
  };

  /**
   * Destroys the resources held by this object.  Destroying an object allows for deterministic
   * release of resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  CreditDisplay.prototype.destroy = function () {
    this._lightbox.removeEventListener("click", this._hideLightbox, false);

    this.container.removeChild(this._cesiumCreditContainer);
    this.container.removeChild(this._screenContainer);
    this.container.removeChild(this._expandLink);
    this.viewport.removeChild(this._lightbox);

    return destroyObject(this);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  CreditDisplay.prototype.isDestroyed = function () {
    return false;
  };

  CreditDisplay._cesiumCredit = undefined;
  CreditDisplay._cesiumCreditInitialized = false;

  var defaultCredit;
  function getDefaultCredit() {
    if (!defined(defaultCredit)) {
      var logo = buildModuleUrl("Assets/Images/ion-credit.png");

      // When hosting in a WebView, the base URL scheme is file:// or ms-appx-web://
      // which is stripped out from the Credit's <img> tag; use the full path instead
      if (logo.indexOf("http://") !== 0 && logo.indexOf("https://") !== 0) {
        var logoUrl = new URI(logo);
        logo = logoUrl.getPath();
      }

      defaultCredit = new Credit(
        '<a href="https://cesium.com/" target="_blank"><img src="' +
          logo +
          '" title="Cesium ion"/></a>',
        true
      );
    }

    if (!CreditDisplay._cesiumCreditInitialized) {
      CreditDisplay._cesiumCredit = defaultCredit;
      CreditDisplay._cesiumCreditInitialized = true;
    }
    return defaultCredit;
  }

  Object.defineProperties(CreditDisplay, {
    /**
     * Gets or sets the Cesium logo credit.
     * @memberof CreditDisplay
     * @type {Credit}
     */
    cesiumCredit: {
      get: function () {
        getDefaultCredit();
        return CreditDisplay._cesiumCredit;
      },
      set: function (value) {
        CreditDisplay._cesiumCredit = value;
        CreditDisplay._cesiumCreditInitialized = true;
      },
    },
  });

  /**
   * Visualizes a vertex attribute by displaying it as a color for debugging.
   * <p>
   * Components for well-known unit-length vectors, i.e., <code>normal</code>,
   * <code>tangent</code>, and <code>bitangent</code>, are scaled and biased
   * from [-1.0, 1.0] to (-1.0, 1.0).
   * </p>
   *
   * @alias DebugAppearance
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {String} options.attributeName The name of the attribute to visualize.
   * @param {Boolean} [options.perInstanceAttribute=false] Boolean that determines whether this attribute is a per-instance geometry attribute.
   * @param {String} [options.glslDatatype='vec3'] The GLSL datatype of the attribute.  Supported datatypes are <code>float</code>, <code>vec2</code>, <code>vec3</code>, and <code>vec4</code>.
   * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
   * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
   * @param {Object} [options.renderState] Optional render state to override the default render state.
   *
   * @exception {DeveloperError} options.glslDatatype must be float, vec2, vec3, or vec4.
   *
   * @example
   * var primitive = new Cesium.Primitive({
   *   geometryInstances : // ...
   *   appearance : new Cesium.DebugAppearance({
   *     attributeName : 'normal'
   *   })
   * });
   */
  function DebugAppearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var attributeName = options.attributeName;
    var perInstanceAttribute = options.perInstanceAttribute;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(attributeName)) {
      throw new DeveloperError("options.attributeName is required.");
    }
    //>>includeEnd('debug');

    if (!defined(perInstanceAttribute)) {
      perInstanceAttribute = false;
    }

    var glslDatatype = defaultValue(options.glslDatatype, "vec3");
    var varyingName = "v_" + attributeName;
    var getColor;

    // Well-known normalized vector attributes in VertexFormat
    if (
      attributeName === "normal" ||
      attributeName === "tangent" ||
      attributeName === "bitangent"
    ) {
      getColor =
        "vec4 getColor() { return vec4((" +
        varyingName +
        " + vec3(1.0)) * 0.5, 1.0); }\n";
    } else {
      // All other attributes, both well-known and custom
      if (attributeName === "st") {
        glslDatatype = "vec2";
      }

      switch (glslDatatype) {
        case "float":
          getColor =
            "vec4 getColor() { return vec4(vec3(" + varyingName + "), 1.0); }\n";
          break;
        case "vec2":
          getColor =
            "vec4 getColor() { return vec4(" + varyingName + ", 0.0, 1.0); }\n";
          break;
        case "vec3":
          getColor =
            "vec4 getColor() { return vec4(" + varyingName + ", 1.0); }\n";
          break;
        case "vec4":
          getColor = "vec4 getColor() { return " + varyingName + "; }\n";
          break;
        //>>includeStart('debug', pragmas.debug);
        default:
          throw new DeveloperError(
            "options.glslDatatype must be float, vec2, vec3, or vec4."
          );
        //>>includeEnd('debug');
      }
    }

    var vs =
      "attribute vec3 position3DHigh;\n" +
      "attribute vec3 position3DLow;\n" +
      "attribute float batchId;\n" +
      (perInstanceAttribute
        ? ""
        : "attribute " + glslDatatype + " " + attributeName + ";\n") +
      "varying " +
      glslDatatype +
      " " +
      varyingName +
      ";\n" +
      "void main()\n" +
      "{\n" +
      "vec4 p = czm_translateRelativeToEye(position3DHigh, position3DLow);\n" +
      (perInstanceAttribute
        ? varyingName + " = czm_batchTable_" + attributeName + "(batchId);\n"
        : varyingName + " = " + attributeName + ";\n") +
      "gl_Position = czm_modelViewProjectionRelativeToEye * p;\n" +
      "}";
    var fs =
      "varying " +
      glslDatatype +
      " " +
      varyingName +
      ";\n" +
      getColor +
      "\n" +
      "void main()\n" +
      "{\n" +
      "gl_FragColor = getColor();\n" +
      "}";

    /**
     * This property is part of the {@link Appearance} interface, but is not
     * used by {@link DebugAppearance} since a fully custom fragment shader is used.
     *
     * @type Material
     *
     * @default undefined
     */
    this.material = undefined;

    /**
     * When <code>true</code>, the geometry is expected to appear translucent.
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.translucent = defaultValue(options.translucent, false);

    this._vertexShaderSource = defaultValue(options.vertexShaderSource, vs);
    this._fragmentShaderSource = defaultValue(options.fragmentShaderSource, fs);
    this._renderState = Appearance.getDefaultRenderState(
      false,
      false,
      options.renderState
    );
    this._closed = defaultValue(options.closed, false);

    // Non-derived members

    this._attributeName = attributeName;
    this._glslDatatype = glslDatatype;
  }

  Object.defineProperties(DebugAppearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof DebugAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },

    /**
     * The GLSL source code for the fragment shader.  The full fragment shader
     * source is built procedurally taking into account the {@link DebugAppearance#material}.
     * Use {@link DebugAppearance#getFragmentShaderSource} to get the full source.
     *
     * @memberof DebugAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     *
     * @memberof DebugAppearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed.
     *
     * @memberof DebugAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },

    /**
     * The name of the attribute being visualized.
     *
     * @memberof DebugAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    attributeName: {
      get: function () {
        return this._attributeName;
      },
    },

    /**
     * The GLSL datatype of the attribute being visualized.
     *
     * @memberof DebugAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    glslDatatype: {
      get: function () {
        return this._glslDatatype;
      },
    },
  });

  /**
   * Returns the full GLSL fragment shader source, which for {@link DebugAppearance} is just
   * {@link DebugAppearance#fragmentShaderSource}.
   *
   * @function
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  DebugAppearance.prototype.getFragmentShaderSource =
    Appearance.prototype.getFragmentShaderSource;

  /**
   * Determines if the geometry is translucent based on {@link DebugAppearance#translucent}.
   *
   * @function
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  DebugAppearance.prototype.isTranslucent = Appearance.prototype.isTranslucent;

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @function
   *
   * @returns {Object} The render state.
   */
  DebugAppearance.prototype.getRenderState = Appearance.prototype.getRenderState;

  /**
   * Draws the outline of the camera's view frustum.
   *
   * @alias DebugCameraPrimitive
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Camera} options.camera The camera.
   * @param {Number[]} [options.frustumSplits] Distances to the near and far planes of the camera frustums. This overrides the camera's frustum near and far values.
   * @param {Color} [options.color=Color.CYAN] The color of the debug outline.
   * @param {Boolean} [options.updateOnChange=true] Whether the primitive updates when the underlying camera changes.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Object} [options.id] A user-defined object to return when the instance is picked with {@link Scene#pick}.
   *
   * @example
   * primitives.add(new Cesium.DebugCameraPrimitive({
   *   camera : camera,
   *   color : Cesium.Color.YELLOW
   * }));
   */
  function DebugCameraPrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.camera)) {
      throw new DeveloperError("options.camera is required.");
    }
    //>>includeEnd('debug');

    this._camera = options.camera;
    this._frustumSplits = options.frustumSplits;
    this._color = defaultValue(options.color, Color.CYAN);
    this._updateOnChange = defaultValue(options.updateOnChange, true);

    /**
     * Determines if this primitive will be shown.
     *
     * @type Boolean
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * User-defined value returned when the primitive is picked.
     *
     * @type {*}
     * @default undefined
     *
     * @see Scene#pick
     */
    this.id = options.id;
    this._id = undefined;

    this._outlinePrimitives = [];
    this._planesPrimitives = [];
  }

  var scratchRight$1 = new Cartesian3();
  var scratchRotation$1 = new Matrix3();
  var scratchOrientation = new Quaternion();
  var scratchPerspective = new PerspectiveFrustum();
  var scratchPerspectiveOffCenter = new PerspectiveOffCenterFrustum();
  var scratchOrthographic = new OrthographicFrustum();
  var scratchOrthographicOffCenter = new OrthographicOffCenterFrustum();

  var scratchColor$k = new Color();
  var scratchSplits = [1.0, 100000.0];

  /**
   * @private
   */
  DebugCameraPrimitive.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    var planesPrimitives = this._planesPrimitives;
    var outlinePrimitives = this._outlinePrimitives;
    var i;
    var length;

    if (this._updateOnChange) {
      // Recreate the primitive every frame
      length = planesPrimitives.length;
      for (i = 0; i < length; ++i) {
        outlinePrimitives[i] =
          outlinePrimitives[i] && outlinePrimitives[i].destroy();
        planesPrimitives[i] =
          planesPrimitives[i] && planesPrimitives[i].destroy();
      }
      planesPrimitives.length = 0;
      outlinePrimitives.length = 0;
    }

    if (planesPrimitives.length === 0) {
      var camera = this._camera;
      var cameraFrustum = camera.frustum;
      var frustum;
      if (cameraFrustum instanceof PerspectiveFrustum) {
        frustum = scratchPerspective;
      } else if (cameraFrustum instanceof PerspectiveOffCenterFrustum) {
        frustum = scratchPerspectiveOffCenter;
      } else if (cameraFrustum instanceof OrthographicFrustum) {
        frustum = scratchOrthographic;
      } else {
        frustum = scratchOrthographicOffCenter;
      }
      frustum = cameraFrustum.clone(frustum);

      var numFrustums;
      var frustumSplits = this._frustumSplits;
      if (!defined(frustumSplits) || frustumSplits.length <= 1) {
        // Use near and far planes if no splits created
        frustumSplits = scratchSplits;
        frustumSplits[0] = this._camera.frustum.near;
        frustumSplits[1] = this._camera.frustum.far;
        numFrustums = 1;
      } else {
        numFrustums = frustumSplits.length - 1;
      }

      var position = camera.positionWC;
      var direction = camera.directionWC;
      var up = camera.upWC;
      var right = camera.rightWC;
      right = Cartesian3.negate(right, scratchRight$1);

      var rotation = scratchRotation$1;
      Matrix3.setColumn(rotation, 0, right, rotation);
      Matrix3.setColumn(rotation, 1, up, rotation);
      Matrix3.setColumn(rotation, 2, direction, rotation);

      var orientation = Quaternion.fromRotationMatrix(
        rotation,
        scratchOrientation
      );

      planesPrimitives.length = outlinePrimitives.length = numFrustums;

      for (i = 0; i < numFrustums; ++i) {
        frustum.near = frustumSplits[i];
        frustum.far = frustumSplits[i + 1];

        planesPrimitives[i] = new Primitive({
          geometryInstances: new GeometryInstance({
            geometry: new FrustumGeometry({
              origin: position,
              orientation: orientation,
              frustum: frustum,
              _drawNearPlane: i === 0,
            }),
            attributes: {
              color: ColorGeometryInstanceAttribute.fromColor(
                Color.fromAlpha(this._color, 0.1, scratchColor$k)
              ),
            },
            id: this.id,
            pickPrimitive: this,
          }),
          appearance: new PerInstanceColorAppearance({
            translucent: true,
            flat: true,
          }),
          asynchronous: false,
        });

        outlinePrimitives[i] = new Primitive({
          geometryInstances: new GeometryInstance({
            geometry: new FrustumOutlineGeometry({
              origin: position,
              orientation: orientation,
              frustum: frustum,
              _drawNearPlane: i === 0,
            }),
            attributes: {
              color: ColorGeometryInstanceAttribute.fromColor(this._color),
            },
            id: this.id,
            pickPrimitive: this,
          }),
          appearance: new PerInstanceColorAppearance({
            translucent: false,
            flat: true,
          }),
          asynchronous: false,
        });
      }
    }

    length = planesPrimitives.length;
    for (i = 0; i < length; ++i) {
      outlinePrimitives[i].update(frameState);
      planesPrimitives[i].update(frameState);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see DebugCameraPrimitive#destroy
   */
  DebugCameraPrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * p = p && p.destroy();
   *
   * @see DebugCameraPrimitive#isDestroyed
   */
  DebugCameraPrimitive.prototype.destroy = function () {
    var length = this._planesPrimitives.length;
    for (var i = 0; i < length; ++i) {
      this._outlinePrimitives[i] =
        this._outlinePrimitives[i] && this._outlinePrimitives[i].destroy();
      this._planesPrimitives[i] =
        this._planesPrimitives[i] && this._planesPrimitives[i].destroy();
    }
    return destroyObject(this);
  };

  /**
   * @private
   */
  function DebugInspector() {
    this._cachedShowFrustumsShaders = {};
  }

  function getAttributeLocations$2(shaderProgram) {
    var attributeLocations = {};
    var attributes = shaderProgram.vertexAttributes;
    for (var a in attributes) {
      if (attributes.hasOwnProperty(a)) {
        attributeLocations[a] = attributes[a].index;
      }
    }

    return attributeLocations;
  }

  function createDebugShowFrustumsShaderProgram(scene, shaderProgram) {
    var context = scene.context;
    var sp = shaderProgram;
    var fs = sp.fragmentShaderSource.clone();

    var targets = [];
    fs.sources = fs.sources.map(function (source) {
      source = ShaderSource.replaceMain(source, "czm_Debug_main");
      var re = /gl_FragData\[(\d+)\]/g;
      var match;
      while ((match = re.exec(source)) !== null) {
        if (targets.indexOf(match[1]) === -1) {
          targets.push(match[1]);
        }
      }
      return source;
    });
    var length = targets.length;

    var newMain = "";
    newMain += "uniform vec3 debugShowCommandsColor;\n";
    newMain += "uniform vec3 debugShowFrustumsColor;\n";
    newMain += "void main() \n" + "{ \n" + "    czm_Debug_main(); \n";

    // set debugShowCommandsColor to Color(1.0, 1.0, 1.0, 1.0) to stop rendering scene.debugShowCommands
    // set debugShowFrustumsColor to Color(1.0, 1.0, 1.0, 1.0) to stop rendering scene.debugShowFrustums
    var i;
    if (length > 0) {
      for (i = 0; i < length; ++i) {
        newMain +=
          "    gl_FragData[" + targets[i] + "].rgb *= debugShowCommandsColor;\n";
        newMain +=
          "    gl_FragData[" + targets[i] + "].rgb *= debugShowFrustumsColor;\n";
      }
    } else {
      newMain += "    gl_FragColor.rgb *= debugShowCommandsColor;\n";
      newMain += "    gl_FragColor.rgb *= debugShowFrustumsColor;\n";
    }
    newMain += "}";

    fs.sources.push(newMain);

    var attributeLocations = getAttributeLocations$2(sp);

    return ShaderProgram.fromCache({
      context: context,
      vertexShaderSource: sp.vertexShaderSource,
      fragmentShaderSource: fs,
      attributeLocations: attributeLocations,
    });
  }

  var scratchFrustumColor = new Color();
  function createDebugShowFrustumsUniformMap(scene, command) {
    // setup uniform for the shader
    var debugUniformMap;
    if (!defined(command.uniformMap)) {
      debugUniformMap = {};
    } else {
      debugUniformMap = command.uniformMap;
    }

    if (
      defined(debugUniformMap.debugShowCommandsColor) ||
      defined(debugUniformMap.debugShowFrustumsColor)
    ) {
      return debugUniformMap;
    }

    debugUniformMap.debugShowCommandsColor = function () {
      if (!scene.debugShowCommands) {
        return Color.WHITE;
      }

      if (!defined(command._debugColor)) {
        command._debugColor = Color.fromRandom();
      }

      return command._debugColor;
    };

    debugUniformMap.debugShowFrustumsColor = function () {
      if (!scene.debugShowFrustums) {
        return Color.WHITE;
      }

      // Support up to three frustums.  If a command overlaps all
      // three, it's code is not changed.
      scratchFrustumColor.red =
        command.debugOverlappingFrustums & (1 << 0) ? 1.0 : 0.0;
      scratchFrustumColor.green =
        command.debugOverlappingFrustums & (1 << 1) ? 1.0 : 0.0;
      scratchFrustumColor.blue =
        command.debugOverlappingFrustums & (1 << 2) ? 1.0 : 0.0;
      scratchFrustumColor.alpha = 1.0;
      return scratchFrustumColor;
    };

    return debugUniformMap;
  }

  var scratchShowFrustumCommand = new DrawCommand();
  DebugInspector.prototype.executeDebugShowFrustumsCommand = function (
    scene,
    command,
    passState
  ) {
    // create debug command
    var shaderProgramId = command.shaderProgram.id;
    var debugShaderProgram = this._cachedShowFrustumsShaders[shaderProgramId];
    if (!defined(debugShaderProgram)) {
      debugShaderProgram = createDebugShowFrustumsShaderProgram(
        scene,
        command.shaderProgram
      );

      this._cachedShowFrustumsShaders[shaderProgramId] = debugShaderProgram;
    }

    var debugCommand = DrawCommand.shallowClone(
      command,
      scratchShowFrustumCommand
    );
    debugCommand.shaderProgram = debugShaderProgram;
    debugCommand.uniformMap = createDebugShowFrustumsUniformMap(scene, command);
    debugCommand.execute(scene.context, passState);
  };

  /**
   * Draws the axes of a reference frame defined by a matrix that transforms to world
   * coordinates, i.e., Earth's WGS84 coordinates.  The most prominent example is
   * a primitives <code>modelMatrix</code>.
   * <p>
   * The X axis is red; Y is green; and Z is blue.
   * </p>
   * <p>
   * This is for debugging only; it is not optimized for production use.
   * </p>
   *
   * @alias DebugModelMatrixPrimitive
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Number} [options.length=10000000.0] The length of the axes in meters.
   * @param {Number} [options.width=2.0] The width of the axes in pixels.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 matrix that defines the reference frame, i.e., origin plus axes, to visualize.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Object} [options.id] A user-defined object to return when the instance is picked with {@link Scene#pick}
   *
   * @example
   * primitives.add(new Cesium.DebugModelMatrixPrimitive({
   *   modelMatrix : primitive.modelMatrix,  // primitive to debug
   *   length : 100000.0,
   *   width : 10.0
   * }));
   */
  function DebugModelMatrixPrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The length of the axes in meters.
     *
     * @type {Number}
     * @default 10000000.0
     */
    this.length = defaultValue(options.length, 10000000.0);
    this._length = undefined;

    /**
     * The width of the axes in pixels.
     *
     * @type {Number}
     * @default 2.0
     */
    this.width = defaultValue(options.width, 2.0);
    this._width = undefined;

    /**
     * Determines if this primitive will be shown.
     *
     * @type Boolean
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * The 4x4 matrix that defines the reference frame, i.e., origin plus axes, to visualize.
     *
     * @type {Matrix4}
     * @default {@link Matrix4.IDENTITY}
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = new Matrix4();

    /**
     * User-defined value returned when the primitive is picked.
     *
     * @type {*}
     * @default undefined
     *
     * @see Scene#pick
     */
    this.id = options.id;
    this._id = undefined;

    this._primitive = undefined;
  }

  /**
   * @private
   */
  DebugModelMatrixPrimitive.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    if (
      !defined(this._primitive) ||
      !Matrix4.equals(this._modelMatrix, this.modelMatrix) ||
      this._length !== this.length ||
      this._width !== this.width ||
      this._id !== this.id
    ) {
      this._modelMatrix = Matrix4.clone(this.modelMatrix, this._modelMatrix);
      this._length = this.length;
      this._width = this.width;
      this._id = this.id;

      if (defined(this._primitive)) {
        this._primitive.destroy();
      }

      // Workaround projecting (0, 0, 0)
      if (
        this.modelMatrix[12] === 0.0 &&
        this.modelMatrix[13] === 0.0 &&
        this.modelMatrix[14] === 0.0
      ) {
        this.modelMatrix[14] = 0.01;
      }

      var x = new GeometryInstance({
        geometry: new PolylineGeometry({
          positions: [Cartesian3.ZERO, Cartesian3.UNIT_X],
          width: this.width,
          vertexFormat: PolylineColorAppearance.VERTEX_FORMAT,
          colors: [Color.RED, Color.RED],
          arcType: ArcType$1.NONE,
        }),
        modelMatrix: Matrix4.multiplyByUniformScale(
          this.modelMatrix,
          this.length,
          new Matrix4()
        ),
        id: this.id,
        pickPrimitive: this,
      });
      var y = new GeometryInstance({
        geometry: new PolylineGeometry({
          positions: [Cartesian3.ZERO, Cartesian3.UNIT_Y],
          width: this.width,
          vertexFormat: PolylineColorAppearance.VERTEX_FORMAT,
          colors: [Color.GREEN, Color.GREEN],
          arcType: ArcType$1.NONE,
        }),
        modelMatrix: Matrix4.multiplyByUniformScale(
          this.modelMatrix,
          this.length,
          new Matrix4()
        ),
        id: this.id,
        pickPrimitive: this,
      });
      var z = new GeometryInstance({
        geometry: new PolylineGeometry({
          positions: [Cartesian3.ZERO, Cartesian3.UNIT_Z],
          width: this.width,
          vertexFormat: PolylineColorAppearance.VERTEX_FORMAT,
          colors: [Color.BLUE, Color.BLUE],
          arcType: ArcType$1.NONE,
        }),
        modelMatrix: Matrix4.multiplyByUniformScale(
          this.modelMatrix,
          this.length,
          new Matrix4()
        ),
        id: this.id,
        pickPrimitive: this,
      });

      this._primitive = new Primitive({
        geometryInstances: [x, y, z],
        appearance: new PolylineColorAppearance(),
        asynchronous: false,
      });
    }

    this._primitive.update(frameState);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see DebugModelMatrixPrimitive#destroy
   */
  DebugModelMatrixPrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * p = p && p.destroy();
   *
   * @see DebugModelMatrixPrimitive#isDestroyed
   */
  DebugModelMatrixPrimitive.prototype.destroy = function () {
    this._primitive = this._primitive && this._primitive.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var DepthPlaneFS = "varying vec4 positionEC;\n\
void main()\n\
{\n\
vec3 position;\n\
vec3 direction;\n\
if (czm_orthographicIn3D == 1.0)\n\
{\n\
vec2 uv = (gl_FragCoord.xy -  czm_viewport.xy) / czm_viewport.zw;\n\
vec2 minPlane = vec2(czm_frustumPlanes.z, czm_frustumPlanes.y);\n\
vec2 maxPlane = vec2(czm_frustumPlanes.w, czm_frustumPlanes.x);\n\
position = vec3(mix(minPlane, maxPlane, uv), 0.0);\n\
direction = vec3(0.0, 0.0, -1.0);\n\
}\n\
else\n\
{\n\
position = vec3(0.0);\n\
direction = normalize(positionEC.xyz);\n\
}\n\
czm_ray ray = czm_ray(position, direction);\n\
vec3 ellipsoid_center = czm_view[3].xyz;\n\
czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid_center, czm_ellipsoidInverseRadii);\n\
if (!czm_isEmpty(intersection))\n\
{\n\
gl_FragColor = vec4(1.0, 1.0, 0.0, 1.0);\n\
}\n\
else\n\
{\n\
discard;\n\
}\n\
czm_writeLogDepth();\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var DepthPlaneVS = "attribute vec4 position;\n\
varying vec4 positionEC;\n\
void main()\n\
{\n\
positionEC = czm_modelView * position;\n\
gl_Position = czm_projection * positionEC;\n\
czm_vertexLogDepth();\n\
}\n\
";

  /**
   * @private
   */
  function DepthPlane() {
    this._rs = undefined;
    this._sp = undefined;
    this._va = undefined;
    this._command = undefined;
    this._mode = undefined;
    this._useLogDepth = false;
  }

  var depthQuadScratch = FeatureDetection.supportsTypedArrays()
    ? new Float32Array(12)
    : [];
  var scratchCartesian1$7 = new Cartesian3();
  var scratchCartesian2$a = new Cartesian3();
  var scratchCartesian3$d = new Cartesian3();
  var scratchCartesian4$5 = new Cartesian3();
  var scratchCartesian5$2 = new Cartesian3();

  function computeDepthQuad(ellipsoid, frameState) {
    var radii = ellipsoid.radii;
    var camera = frameState.camera;
    var center, eastOffset, northOffset;

    if (camera.frustum instanceof OrthographicFrustum) {
      center = Cartesian3.ZERO;
      eastOffset = camera.rightWC;
      northOffset = camera.upWC;
    } else {
      var p = camera.positionWC;

      // Find the corresponding position in the scaled space of the ellipsoid.
      var q = Cartesian3.multiplyComponents(
        ellipsoid.oneOverRadii,
        p,
        scratchCartesian1$7
      );

      var qUnit = Cartesian3.normalize(q, scratchCartesian2$a);

      // Determine the east and north directions at q.
      var eUnit = Cartesian3.normalize(
        Cartesian3.cross(Cartesian3.UNIT_Z, q, scratchCartesian3$d),
        scratchCartesian3$d
      );
      var nUnit = Cartesian3.normalize(
        Cartesian3.cross(qUnit, eUnit, scratchCartesian4$5),
        scratchCartesian4$5
      );

      var qMagnitude = Cartesian3.magnitude(q);

      // Determine the radius of the 'limb' of the ellipsoid.
      var wMagnitude = Math.sqrt(qMagnitude * qMagnitude - 1.0);

      // Compute the center and offsets.
      center = Cartesian3.multiplyByScalar(
        qUnit,
        1.0 / qMagnitude,
        scratchCartesian1$7
      );
      var scalar = wMagnitude / qMagnitude;
      eastOffset = Cartesian3.multiplyByScalar(eUnit, scalar, scratchCartesian2$a);
      northOffset = Cartesian3.multiplyByScalar(nUnit, scalar, scratchCartesian3$d);
    }

    // A conservative measure for the longitudes would be to use the min/max longitudes of the bounding frustum.
    var upperLeft = Cartesian3.add(center, northOffset, scratchCartesian5$2);
    Cartesian3.subtract(upperLeft, eastOffset, upperLeft);
    Cartesian3.multiplyComponents(radii, upperLeft, upperLeft);
    Cartesian3.pack(upperLeft, depthQuadScratch, 0);

    var lowerLeft = Cartesian3.subtract(center, northOffset, scratchCartesian5$2);
    Cartesian3.subtract(lowerLeft, eastOffset, lowerLeft);
    Cartesian3.multiplyComponents(radii, lowerLeft, lowerLeft);
    Cartesian3.pack(lowerLeft, depthQuadScratch, 3);

    var upperRight = Cartesian3.add(center, northOffset, scratchCartesian5$2);
    Cartesian3.add(upperRight, eastOffset, upperRight);
    Cartesian3.multiplyComponents(radii, upperRight, upperRight);
    Cartesian3.pack(upperRight, depthQuadScratch, 6);

    var lowerRight = Cartesian3.subtract(center, northOffset, scratchCartesian5$2);
    Cartesian3.add(lowerRight, eastOffset, lowerRight);
    Cartesian3.multiplyComponents(radii, lowerRight, lowerRight);
    Cartesian3.pack(lowerRight, depthQuadScratch, 9);

    return depthQuadScratch;
  }

  DepthPlane.prototype.update = function (frameState) {
    this._mode = frameState.mode;
    if (frameState.mode !== SceneMode$1.SCENE3D) {
      return;
    }

    var context = frameState.context;
    var ellipsoid = frameState.mapProjection.ellipsoid;
    var useLogDepth = frameState.useLogDepth;

    if (!defined(this._command)) {
      this._rs = RenderState.fromCache({
        // Write depth, not color
        cull: {
          enabled: true,
        },
        depthTest: {
          enabled: true,
        },
        colorMask: {
          red: false,
          green: false,
          blue: false,
          alpha: false,
        },
      });

      this._command = new DrawCommand({
        renderState: this._rs,
        boundingVolume: new BoundingSphere(
          Cartesian3.ZERO,
          ellipsoid.maximumRadius
        ),
        pass: Pass$1.OPAQUE,
        owner: this,
      });
    }

    if (!defined(this._sp) || this._useLogDepth !== useLogDepth) {
      this._useLogDepth = useLogDepth;

      var vs = new ShaderSource({
        sources: [DepthPlaneVS],
      });
      var fs = new ShaderSource({
        sources: [DepthPlaneFS],
      });
      if (useLogDepth) {
        var extension =
          "#ifdef GL_EXT_frag_depth \n" +
          "#extension GL_EXT_frag_depth : enable \n" +
          "#endif \n\n";

        fs.sources.push(extension);
        fs.defines.push("LOG_DEPTH");
        vs.defines.push("LOG_DEPTH");
      }

      this._sp = ShaderProgram.replaceCache({
        shaderProgram: this._sp,
        context: context,
        vertexShaderSource: vs,
        fragmentShaderSource: fs,
        attributeLocations: {
          position: 0,
        },
      });

      this._command.shaderProgram = this._sp;
    }

    // update depth plane
    var depthQuad = computeDepthQuad(ellipsoid, frameState);

    // depth plane
    if (!defined(this._va)) {
      var geometry = new Geometry({
        attributes: {
          position: new GeometryAttribute({
            componentDatatype: ComponentDatatype$1.FLOAT,
            componentsPerAttribute: 3,
            values: depthQuad,
          }),
        },
        indices: [0, 1, 2, 2, 1, 3],
        primitiveType: PrimitiveType$1.TRIANGLES,
      });

      this._va = VertexArray.fromGeometry({
        context: context,
        geometry: geometry,
        attributeLocations: {
          position: 0,
        },
        bufferUsage: BufferUsage$1.DYNAMIC_DRAW,
      });

      this._command.vertexArray = this._va;
    } else {
      this._va.getAttribute(0).vertexBuffer.copyFromArrayView(depthQuad);
    }
  };

  DepthPlane.prototype.execute = function (context, passState) {
    if (this._mode === SceneMode$1.SCENE3D) {
      this._command.execute(context, passState);
    }
  };

  DepthPlane.prototype.isDestroyed = function () {
    return false;
  };

  DepthPlane.prototype.destroy = function () {
    this._sp = this._sp && this._sp.destroy();
    this._va = this._va && this._va.destroy();
  };

  /**
   * @private
   */
  function DerivedCommand() {}

  var fragDepthRegex = /\bgl_FragDepthEXT\b/;
  var discardRegex = /\bdiscard\b/;

  function getDepthOnlyShaderProgram(context, shaderProgram) {
    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      "depthOnly"
    );
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;
      var fs = shaderProgram.fragmentShaderSource;

      var i;
      var writesDepthOrDiscards = false;
      var sources = fs.sources;
      var length = sources.length;
      for (i = 0; i < length; ++i) {
        if (fragDepthRegex.test(sources[i]) || discardRegex.test(sources[i])) {
          writesDepthOrDiscards = true;
          break;
        }
      }

      var usesLogDepth = false;
      var defines = fs.defines;
      length = defines.length;
      for (i = 0; i < length; ++i) {
        if (defines[i] === "LOG_DEPTH") {
          usesLogDepth = true;
          break;
        }
      }

      var source;
      if (!writesDepthOrDiscards && !usesLogDepth) {
        source =
          "void main() \n" + "{ \n" + "    gl_FragColor = vec4(1.0); \n" + "} \n";
        fs = new ShaderSource({
          sources: [source],
        });
      } else if (!writesDepthOrDiscards && usesLogDepth) {
        source =
          "#ifdef GL_EXT_frag_depth \n" +
          "#extension GL_EXT_frag_depth : enable \n" +
          "#endif \n\n" +
          "void main() \n" +
          "{ \n" +
          "    gl_FragColor = vec4(1.0); \n" +
          "    czm_writeLogDepth(); \n" +
          "} \n";
        fs = new ShaderSource({
          defines: ["LOG_DEPTH"],
          sources: [source],
        });
      }

      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        "depthOnly",
        {
          vertexShaderSource: shaderProgram.vertexShaderSource,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  function getDepthOnlyRenderState(scene, renderState) {
    var cache = scene._depthOnlyRenderStateCache;
    var depthOnlyState = cache[renderState.id];
    if (!defined(depthOnlyState)) {
      var rs = RenderState.getState(renderState);
      rs.depthMask = true;
      rs.colorMask = {
        red: false,
        green: false,
        blue: false,
        alpha: false,
      };

      depthOnlyState = RenderState.fromCache(rs);
      cache[renderState.id] = depthOnlyState;
    }

    return depthOnlyState;
  }

  DerivedCommand.createDepthOnlyDerivedCommand = function (
    scene,
    command,
    context,
    result
  ) {
    // For a depth only pass, we bind a framebuffer with only a depth attachment (no color attachments),
    // do not write color, and write depth. If the fragment shader doesn't modify the fragment depth
    // or discard, the driver can replace the fragment shader with a pass-through shader. We're unsure if this
    // actually happens so we modify the shader to use a pass-through fragment shader.

    if (!defined(result)) {
      result = {};
    }

    var shader;
    var renderState;
    if (defined(result.depthOnlyCommand)) {
      shader = result.depthOnlyCommand.shaderProgram;
      renderState = result.depthOnlyCommand.renderState;
    }

    result.depthOnlyCommand = DrawCommand.shallowClone(
      command,
      result.depthOnlyCommand
    );

    if (!defined(shader) || result.shaderProgramId !== command.shaderProgram.id) {
      result.depthOnlyCommand.shaderProgram = getDepthOnlyShaderProgram(
        context,
        command.shaderProgram
      );
      result.depthOnlyCommand.renderState = getDepthOnlyRenderState(
        scene,
        command.renderState
      );
      result.shaderProgramId = command.shaderProgram.id;
    } else {
      result.depthOnlyCommand.shaderProgram = shader;
      result.depthOnlyCommand.renderState = renderState;
    }

    return result;
  };

  var writeLogDepthRegex = /\s+czm_writeLogDepth\(/;
  var vertexlogDepthRegex = /\s+czm_vertexLogDepth\(/;
  var extensionRegex = /\s*#extension\s+GL_EXT_frag_depth\s*:\s*enable/;

  function getLogDepthShaderProgram(context, shaderProgram) {
    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      "logDepth"
    );
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;
      var vs = shaderProgram.vertexShaderSource.clone();
      var fs = shaderProgram.fragmentShaderSource.clone();

      vs.defines = defined(vs.defines) ? vs.defines.slice(0) : [];
      vs.defines.push("LOG_DEPTH");
      fs.defines = defined(fs.defines) ? fs.defines.slice(0) : [];
      fs.defines.push("LOG_DEPTH");

      var i;
      var logMain;
      var writesLogDepth = false;
      var sources = vs.sources;
      var length = sources.length;
      for (i = 0; i < length; ++i) {
        if (vertexlogDepthRegex.test(sources[i])) {
          writesLogDepth = true;
          break;
        }
      }

      if (!writesLogDepth) {
        for (i = 0; i < length; ++i) {
          sources[i] = ShaderSource.replaceMain(sources[i], "czm_log_depth_main");
        }

        logMain =
          "\n\n" +
          "void main() \n" +
          "{ \n" +
          "    czm_log_depth_main(); \n" +
          "    czm_vertexLogDepth(); \n" +
          "} \n";
        sources.push(logMain);
      }

      sources = fs.sources;
      length = sources.length;

      writesLogDepth = false;
      for (i = 0; i < length; ++i) {
        if (writeLogDepthRegex.test(sources[i])) {
          writesLogDepth = true;
        }
      }
      // This define indicates that a log depth value is written by the shader but doesn't use czm_writeLogDepth.
      if (fs.defines.indexOf("LOG_DEPTH_WRITE") !== -1) {
        writesLogDepth = true;
      }

      var addExtension = true;
      for (i = 0; i < length; ++i) {
        if (extensionRegex.test(sources[i])) {
          addExtension = false;
        }
      }

      var logSource = "";
      if (addExtension) {
        logSource +=
          "#ifdef GL_EXT_frag_depth \n" +
          "#extension GL_EXT_frag_depth : enable \n" +
          "#endif \n\n";
      }

      if (!writesLogDepth) {
        for (i = 0; i < length; i++) {
          sources[i] = ShaderSource.replaceMain(sources[i], "czm_log_depth_main");
        }

        logSource +=
          "\n" +
          "void main() \n" +
          "{ \n" +
          "    czm_log_depth_main(); \n" +
          "    czm_writeLogDepth(); \n" +
          "} \n";
      }

      sources.push(logSource);

      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        "logDepth",
        {
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  DerivedCommand.createLogDepthCommand = function (command, context, result) {
    if (!defined(result)) {
      result = {};
    }

    var shader;
    if (defined(result.command)) {
      shader = result.command.shaderProgram;
    }

    result.command = DrawCommand.shallowClone(command, result.command);

    if (!defined(shader) || result.shaderProgramId !== command.shaderProgram.id) {
      result.command.shaderProgram = getLogDepthShaderProgram(
        context,
        command.shaderProgram
      );
      result.shaderProgramId = command.shaderProgram.id;
    } else {
      result.command.shaderProgram = shader;
    }

    return result;
  };

  function getPickShaderProgram(context, shaderProgram, pickId) {
    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      "pick"
    );
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;
      var fs = shaderProgram.fragmentShaderSource;

      var sources = fs.sources;
      var length = sources.length;

      var newMain =
        "void main() \n" +
        "{ \n" +
        "    czm_non_pick_main(); \n" +
        "    if (gl_FragColor.a == 0.0) { \n" +
        "        discard; \n" +
        "    } \n" +
        "    gl_FragColor = " +
        pickId +
        "; \n" +
        "} \n";
      var newSources = new Array(length + 1);
      for (var i = 0; i < length; ++i) {
        newSources[i] = ShaderSource.replaceMain(sources[i], "czm_non_pick_main");
      }
      newSources[length] = newMain;
      fs = new ShaderSource({
        sources: newSources,
        defines: fs.defines,
      });
      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        "pick",
        {
          vertexShaderSource: shaderProgram.vertexShaderSource,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  function getPickRenderState(scene, renderState) {
    var cache = scene.picking.pickRenderStateCache;
    var pickState = cache[renderState.id];
    if (!defined(pickState)) {
      var rs = RenderState.getState(renderState);
      rs.blending.enabled = false;

      // Turns on depth writing for opaque and translucent passes
      // Overlapping translucent geometry on the globe surface may exhibit z-fighting
      // during the pick pass which may not match the rendered scene. Once
      // terrain is on by default and ground primitives are used instead
      // this will become less of a problem.
      rs.depthMask = true;

      pickState = RenderState.fromCache(rs);
      cache[renderState.id] = pickState;
    }

    return pickState;
  }

  DerivedCommand.createPickDerivedCommand = function (
    scene,
    command,
    context,
    result
  ) {
    if (!defined(result)) {
      result = {};
    }

    var shader;
    var renderState;
    if (defined(result.pickCommand)) {
      shader = result.pickCommand.shaderProgram;
      renderState = result.pickCommand.renderState;
    }

    result.pickCommand = DrawCommand.shallowClone(command, result.pickCommand);

    if (!defined(shader) || result.shaderProgramId !== command.shaderProgram.id) {
      result.pickCommand.shaderProgram = getPickShaderProgram(
        context,
        command.shaderProgram,
        command.pickId
      );
      result.pickCommand.renderState = getPickRenderState(
        scene,
        command.renderState
      );
      result.shaderProgramId = command.shaderProgram.id;
    } else {
      result.pickCommand.shaderProgram = shader;
      result.pickCommand.renderState = renderState;
    }

    return result;
  };

  function getHdrShaderProgram(context, shaderProgram) {
    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      "HDR"
    );
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;
      var vs = shaderProgram.vertexShaderSource.clone();
      var fs = shaderProgram.fragmentShaderSource.clone();

      vs.defines = defined(vs.defines) ? vs.defines.slice(0) : [];
      vs.defines.push("HDR");
      fs.defines = defined(fs.defines) ? fs.defines.slice(0) : [];
      fs.defines.push("HDR");

      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        "HDR",
        {
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  DerivedCommand.createHdrCommand = function (command, context, result) {
    if (!defined(result)) {
      result = {};
    }

    var shader;
    if (defined(result.command)) {
      shader = result.command.shaderProgram;
    }

    result.command = DrawCommand.shallowClone(command, result.command);

    if (!defined(shader) || result.shaderProgramId !== command.shaderProgram.id) {
      result.command.shaderProgram = getHdrShaderProgram(
        context,
        command.shaderProgram
      );
      result.shaderProgramId = command.shaderProgram.id;
    } else {
      result.command.shaderProgram = shader;
    }

    return result;
  };

  /**
   * @private
   */
  function DeviceOrientationCameraController(scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    this._scene = scene;

    this._lastAlpha = undefined;
    this._lastBeta = undefined;
    this._lastGamma = undefined;

    this._alpha = undefined;
    this._beta = undefined;
    this._gamma = undefined;

    var that = this;

    function callback(e) {
      var alpha = e.alpha;
      if (!defined(alpha)) {
        that._alpha = undefined;
        that._beta = undefined;
        that._gamma = undefined;
        return;
      }

      that._alpha = CesiumMath.toRadians(alpha);
      that._beta = CesiumMath.toRadians(e.beta);
      that._gamma = CesiumMath.toRadians(e.gamma);
    }

    window.addEventListener("deviceorientation", callback, false);

    this._removeListener = function () {
      window.removeEventListener("deviceorientation", callback, false);
    };
  }

  var scratchQuaternion1 = new Quaternion();
  var scratchQuaternion2 = new Quaternion();
  var scratchMatrix3$2 = new Matrix3();

  function rotate(camera, alpha, beta, gamma) {
    var direction = camera.direction;
    var right = camera.right;
    var up = camera.up;

    var bQuat = Quaternion.fromAxisAngle(direction, beta, scratchQuaternion2);
    var gQuat = Quaternion.fromAxisAngle(right, gamma, scratchQuaternion1);

    var rotQuat = Quaternion.multiply(gQuat, bQuat, gQuat);

    var aQuat = Quaternion.fromAxisAngle(up, alpha, scratchQuaternion2);
    Quaternion.multiply(aQuat, rotQuat, rotQuat);

    var matrix = Matrix3.fromQuaternion(rotQuat, scratchMatrix3$2);
    Matrix3.multiplyByVector(matrix, right, right);
    Matrix3.multiplyByVector(matrix, up, up);
    Matrix3.multiplyByVector(matrix, direction, direction);
  }

  DeviceOrientationCameraController.prototype.update = function () {
    if (!defined(this._alpha)) {
      return;
    }

    if (!defined(this._lastAlpha)) {
      this._lastAlpha = this._alpha;
      this._lastBeta = this._beta;
      this._lastGamma = this._gamma;
    }

    var a = this._lastAlpha - this._alpha;
    var b = this._lastBeta - this._beta;
    var g = this._lastGamma - this._gamma;

    rotate(this._scene.camera, -a, b, g);

    this._lastAlpha = this._alpha;
    this._lastBeta = this._beta;
    this._lastGamma = this._gamma;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  DeviceOrientationCameraController.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the resources held by this object.  Destroying an object allows for deterministic
   * release of resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  DeviceOrientationCameraController.prototype.destroy = function () {
    this._removeListener();
    return destroyObject(this);
  };

  /**
   * A light that gets emitted in a single direction from infinitely far away.
   *
   * @param {Object} options Object with the following properties:
   * @param {Cartesian3} options.direction The direction in which light gets emitted.
   * @param {Color} [options.color=Color.WHITE] The color of the light.
   * @param {Number} [options.intensity=1.0] The intensity of the light.
   *
   * @exception {DeveloperError} options.direction cannot be zero-length
   *
   * @alias DirectionalLight
   * @constructor
   */
  function DirectionalLight(options) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options", options);
    Check.typeOf.object("options.direction", options.direction);
    if (Cartesian3.equals(options.direction, Cartesian3.ZERO)) {
      throw new DeveloperError("options.direction cannot be zero-length");
    }
    //>>includeEnd('debug');

    /**
     * The direction in which light gets emitted.
     * @type {Cartesian3}
     */
    this.direction = Cartesian3.clone(options.direction);

    /**
     * The color of the light.
     * @type {Color}
     * @default Color.WHITE
     */
    this.color = Color.clone(defaultValue(options.color, Color.WHITE));

    /**
     * The intensity of the light.
     * @type {Number}
     * @default 1.0
     */
    this.intensity = defaultValue(options.intensity, 1.0);
  }

  //This file is automatically rebuilt by the Cesium build process.
  var EllipsoidFS = "#ifdef WRITE_DEPTH\n\
#ifdef GL_EXT_frag_depth\n\
#extension GL_EXT_frag_depth : enable\n\
#endif\n\
#endif\n\
uniform vec3 u_radii;\n\
uniform vec3 u_oneOverEllipsoidRadiiSquared;\n\
varying vec3 v_positionEC;\n\
vec4 computeEllipsoidColor(czm_ray ray, float intersection, float side)\n\
{\n\
vec3 positionEC = czm_pointAlongRay(ray, intersection);\n\
vec3 positionMC = (czm_inverseModelView * vec4(positionEC, 1.0)).xyz;\n\
vec3 geodeticNormal = normalize(czm_geodeticSurfaceNormal(positionMC, vec3(0.0), u_oneOverEllipsoidRadiiSquared));\n\
vec3 sphericalNormal = normalize(positionMC / u_radii);\n\
vec3 normalMC = geodeticNormal * side;\n\
vec3 normalEC = normalize(czm_normal * normalMC);\n\
vec2 st = czm_ellipsoidWgs84TextureCoordinates(sphericalNormal);\n\
vec3 positionToEyeEC = -positionEC;\n\
czm_materialInput materialInput;\n\
materialInput.s = st.s;\n\
materialInput.st = st;\n\
materialInput.str = (positionMC + u_radii) / u_radii;\n\
materialInput.normalEC = normalEC;\n\
materialInput.tangentToEyeMatrix = czm_eastNorthUpToEyeCoordinates(positionMC, normalEC);\n\
materialInput.positionToEyeEC = positionToEyeEC;\n\
czm_material material = czm_getMaterial(materialInput);\n\
#ifdef ONLY_SUN_LIGHTING\n\
return czm_private_phong(normalize(positionToEyeEC), material, czm_sunDirectionEC);\n\
#else\n\
return czm_phong(normalize(positionToEyeEC), material, czm_lightDirectionEC);\n\
#endif\n\
}\n\
void main()\n\
{\n\
float maxRadius = max(u_radii.x, max(u_radii.y, u_radii.z)) * 1.5;\n\
vec3 direction = normalize(v_positionEC);\n\
vec3 ellipsoidCenter = czm_modelView[3].xyz;\n\
float t1 = -1.0;\n\
float t2 = -1.0;\n\
float b = -2.0 * dot(direction, ellipsoidCenter);\n\
float c = dot(ellipsoidCenter, ellipsoidCenter) - maxRadius * maxRadius;\n\
float discriminant = b * b - 4.0 * c;\n\
if (discriminant >= 0.0) {\n\
t1 = (-b - sqrt(discriminant)) * 0.5;\n\
t2 = (-b + sqrt(discriminant)) * 0.5;\n\
}\n\
if (t1 < 0.0 && t2 < 0.0) {\n\
discard;\n\
}\n\
float t = min(t1, t2);\n\
if (t < 0.0) {\n\
t = 0.0;\n\
}\n\
czm_ray ray = czm_ray(t * direction, direction);\n\
vec3 ellipsoid_inverseRadii = vec3(1.0 / u_radii.x, 1.0 / u_radii.y, 1.0 / u_radii.z);\n\
czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoidCenter, ellipsoid_inverseRadii);\n\
if (czm_isEmpty(intersection))\n\
{\n\
discard;\n\
}\n\
vec4 outsideFaceColor = (intersection.start != 0.0) ? computeEllipsoidColor(ray, intersection.start, 1.0) : vec4(0.0);\n\
vec4 insideFaceColor = (outsideFaceColor.a < 1.0) ? computeEllipsoidColor(ray, intersection.stop, -1.0) : vec4(0.0);\n\
gl_FragColor = mix(insideFaceColor, outsideFaceColor, outsideFaceColor.a);\n\
gl_FragColor.a = 1.0 - (1.0 - insideFaceColor.a) * (1.0 - outsideFaceColor.a);\n\
#ifdef WRITE_DEPTH\n\
#ifdef GL_EXT_frag_depth\n\
t = (intersection.start != 0.0) ? intersection.start : intersection.stop;\n\
vec3 positionEC = czm_pointAlongRay(ray, t);\n\
vec4 positionCC = czm_projection * vec4(positionEC, 1.0);\n\
#ifdef LOG_DEPTH\n\
czm_writeLogDepth(1.0 + positionCC.w);\n\
#else\n\
float z = positionCC.z / positionCC.w;\n\
float n = czm_depthRange.near;\n\
float f = czm_depthRange.far;\n\
gl_FragDepthEXT = (z * (f - n) + f + n) * 0.5;\n\
#endif\n\
#endif\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var EllipsoidVS = "attribute vec3 position;\n\
uniform vec3 u_radii;\n\
varying vec3 v_positionEC;\n\
void main()\n\
{\n\
vec4 p = vec4(u_radii * position, 1.0);\n\
v_positionEC = (czm_modelView * p).xyz;\n\
gl_Position = czm_modelViewProjection * p;\n\
gl_Position.z = clamp(gl_Position.z, czm_depthRange.near, czm_depthRange.far);\n\
czm_vertexLogDepth();\n\
}\n\
";

  var attributeLocations$4 = {
    position: 0,
  };

  /**
   * A renderable ellipsoid.  It can also draw spheres when the three {@link EllipsoidPrimitive#radii} components are equal.
   * <p>
   * This is only supported in 3D.  The ellipsoid is not shown in 2D or Columbus view.
   * </p>
   *
   * @alias EllipsoidPrimitive
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Cartesian3} [options.center=Cartesian3.ZERO] The center of the ellipsoid in the ellipsoid's model coordinates.
   * @param {Cartesian3} [options.radii] The radius of the ellipsoid along the <code>x</code>, <code>y</code>, and <code>z</code> axes in the ellipsoid's model coordinates.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the ellipsoid from model to world coordinates.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   * @param {Material} [options.material=Material.ColorType] The surface appearance of the primitive.
   * @param {Object} [options.id] A user-defined object to return when the instance is picked with {@link Scene#pick}
   * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
   *
   * @private
   */
  function EllipsoidPrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The center of the ellipsoid in the ellipsoid's model coordinates.
     * <p>
     * The default is {@link Cartesian3.ZERO}.
     * </p>
     *
     * @type {Cartesian3}
     * @default {@link Cartesian3.ZERO}
     *
     * @see EllipsoidPrimitive#modelMatrix
     */
    this.center = Cartesian3.clone(defaultValue(options.center, Cartesian3.ZERO));
    this._center = new Cartesian3();

    /**
     * The radius of the ellipsoid along the <code>x</code>, <code>y</code>, and <code>z</code> axes in the ellipsoid's model coordinates.
     * When these are the same, the ellipsoid is a sphere.
     * <p>
     * The default is <code>undefined</code>.  The ellipsoid is not drawn until a radii is provided.
     * </p>
     *
     * @type {Cartesian3}
     * @default undefined
     *
     *
     * @example
     * // A sphere with a radius of 2.0
     * e.radii = new Cesium.Cartesian3(2.0, 2.0, 2.0);
     *
     * @see EllipsoidPrimitive#modelMatrix
     */
    this.radii = Cartesian3.clone(options.radii);
    this._radii = new Cartesian3();

    this._oneOverEllipsoidRadiiSquared = new Cartesian3();
    this._boundingSphere = new BoundingSphere();

    /**
     * The 4x4 transformation matrix that transforms the ellipsoid from model to world coordinates.
     * When this is the identity matrix, the ellipsoid is drawn in world coordinates, i.e., Earth's WGS84 coordinates.
     * Local reference frames can be used by providing a different transformation matrix, like that returned
     * by {@link Transforms.eastNorthUpToFixedFrame}.
     *
     * @type {Matrix4}
     * @default {@link Matrix4.IDENTITY}
     *
     * @example
     * var origin = Cesium.Cartesian3.fromDegrees(-95.0, 40.0, 200000.0);
     * e.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._modelMatrix = new Matrix4();
    this._computedModelMatrix = new Matrix4();

    /**
     * Determines if the ellipsoid primitive will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * The surface appearance of the ellipsoid.  This can be one of several built-in {@link Material} objects or a custom material, scripted with
     * {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}.
     * <p>
     * The default material is <code>Material.ColorType</code>.
     * </p>
     *
     * @type {Material}
     * @default Material.fromType(Material.ColorType)
     *
     *
     * @example
     * // 1. Change the color of the default material to yellow
     * e.material.uniforms.color = new Cesium.Color(1.0, 1.0, 0.0, 1.0);
     *
     * // 2. Change material to horizontal stripes
     * e.material = Cesium.Material.fromType(Cesium.Material.StripeType);
     *
     * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
     */
    this.material = defaultValue(
      options.material,
      Material.fromType(Material.ColorType)
    );
    this._material = undefined;
    this._translucent = undefined;

    /**
     * User-defined object returned when the ellipsoid is picked.
     *
     * @type Object
     *
     * @default undefined
     *
     * @see Scene#pick
     */
    this.id = options.id;
    this._id = undefined;

    /**
     * This property is for debugging only; it is not for production use nor is it optimized.
     * <p>
     * Draws the bounding sphere for each draw command in the primitive.
     * </p>
     *
     * @type {Boolean}
     *
     * @default false
     */
    this.debugShowBoundingVolume = defaultValue(
      options.debugShowBoundingVolume,
      false
    );

    /**
     * @private
     */
    this.onlySunLighting = defaultValue(options.onlySunLighting, false);
    this._onlySunLighting = false;

    /**
     * @private
     */
    this._depthTestEnabled = defaultValue(options.depthTestEnabled, true);

    this._useLogDepth = false;

    this._sp = undefined;
    this._rs = undefined;
    this._va = undefined;

    this._pickSP = undefined;
    this._pickId = undefined;

    this._colorCommand = new DrawCommand({
      owner: defaultValue(options._owner, this),
    });
    this._pickCommand = new DrawCommand({
      owner: defaultValue(options._owner, this),
      pickOnly: true,
    });

    var that = this;
    this._uniforms = {
      u_radii: function () {
        return that.radii;
      },
      u_oneOverEllipsoidRadiiSquared: function () {
        return that._oneOverEllipsoidRadiiSquared;
      },
    };

    this._pickUniforms = {
      czm_pickColor: function () {
        return that._pickId.color;
      },
    };
  }

  function getVertexArray(context) {
    var vertexArray = context.cache.ellipsoidPrimitive_vertexArray;

    if (defined(vertexArray)) {
      return vertexArray;
    }

    var geometry = BoxGeometry.createGeometry(
      BoxGeometry.fromDimensions({
        dimensions: new Cartesian3(2.0, 2.0, 2.0),
        vertexFormat: VertexFormat.POSITION_ONLY,
      })
    );

    vertexArray = VertexArray.fromGeometry({
      context: context,
      geometry: geometry,
      attributeLocations: attributeLocations$4,
      bufferUsage: BufferUsage$1.STATIC_DRAW,
      interleave: true,
    });

    context.cache.ellipsoidPrimitive_vertexArray = vertexArray;
    return vertexArray;
  }

  var logDepthExtension =
    "#ifdef GL_EXT_frag_depth \n" +
    "#extension GL_EXT_frag_depth : enable \n" +
    "#endif \n\n";

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} this.material must be defined.
   */
  EllipsoidPrimitive.prototype.update = function (frameState) {
    if (
      !this.show ||
      frameState.mode !== SceneMode$1.SCENE3D ||
      !defined(this.center) ||
      !defined(this.radii)
    ) {
      return;
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(this.material)) {
      throw new DeveloperError("this.material must be defined.");
    }
    //>>includeEnd('debug');

    var context = frameState.context;
    var translucent = this.material.isTranslucent();
    var translucencyChanged = this._translucent !== translucent;

    if (!defined(this._rs) || translucencyChanged) {
      this._translucent = translucent;

      // If this render state is ever updated to use a non-default
      // depth range, the hard-coded values in EllipsoidVS.glsl need
      // to be updated as well.

      this._rs = RenderState.fromCache({
        // Cull front faces - not back faces - so the ellipsoid doesn't
        // disappear if the viewer enters the bounding box.
        cull: {
          enabled: true,
          face: CullFace$1.FRONT,
        },
        depthTest: {
          enabled: this._depthTestEnabled,
        },
        // Only write depth when EXT_frag_depth is supported since the depth for
        // the bounding box is wrong; it is not the true depth of the ray casted ellipsoid.
        depthMask: !translucent && context.fragmentDepth,
        blending: translucent ? BlendingState$1.ALPHA_BLEND : undefined,
      });
    }

    if (!defined(this._va)) {
      this._va = getVertexArray(context);
    }

    var boundingSphereDirty = false;

    var radii = this.radii;
    if (!Cartesian3.equals(this._radii, radii)) {
      Cartesian3.clone(radii, this._radii);

      var r = this._oneOverEllipsoidRadiiSquared;
      r.x = 1.0 / (radii.x * radii.x);
      r.y = 1.0 / (radii.y * radii.y);
      r.z = 1.0 / (radii.z * radii.z);

      boundingSphereDirty = true;
    }

    if (
      !Matrix4.equals(this.modelMatrix, this._modelMatrix) ||
      !Cartesian3.equals(this.center, this._center)
    ) {
      Matrix4.clone(this.modelMatrix, this._modelMatrix);
      Cartesian3.clone(this.center, this._center);

      // Translate model coordinates used for rendering such that the origin is the center of the ellipsoid.
      Matrix4.multiplyByTranslation(
        this.modelMatrix,
        this.center,
        this._computedModelMatrix
      );
      boundingSphereDirty = true;
    }

    if (boundingSphereDirty) {
      Cartesian3.clone(Cartesian3.ZERO, this._boundingSphere.center);
      this._boundingSphere.radius = Cartesian3.maximumComponent(radii);
      BoundingSphere.transform(
        this._boundingSphere,
        this._computedModelMatrix,
        this._boundingSphere
      );
    }

    var materialChanged = this._material !== this.material;
    this._material = this.material;
    this._material.update(context);

    var lightingChanged = this.onlySunLighting !== this._onlySunLighting;
    this._onlySunLighting = this.onlySunLighting;

    var useLogDepth = frameState.useLogDepth;
    var useLogDepthChanged = this._useLogDepth !== useLogDepth;
    this._useLogDepth = useLogDepth;

    var colorCommand = this._colorCommand;
    var vs;
    var fs;

    // Recompile shader when material, lighting, or translucency changes
    if (
      materialChanged ||
      lightingChanged ||
      translucencyChanged ||
      useLogDepthChanged
    ) {
      vs = new ShaderSource({
        sources: [EllipsoidVS],
      });
      fs = new ShaderSource({
        sources: [this.material.shaderSource, EllipsoidFS],
      });
      if (this.onlySunLighting) {
        fs.defines.push("ONLY_SUN_LIGHTING");
      }
      if (!translucent && context.fragmentDepth) {
        fs.defines.push("WRITE_DEPTH");
      }
      if (this._useLogDepth) {
        vs.defines.push("LOG_DEPTH");
        fs.defines.push("LOG_DEPTH");
        fs.sources.push(logDepthExtension);
      }

      this._sp = ShaderProgram.replaceCache({
        context: context,
        shaderProgram: this._sp,
        vertexShaderSource: vs,
        fragmentShaderSource: fs,
        attributeLocations: attributeLocations$4,
      });

      colorCommand.vertexArray = this._va;
      colorCommand.renderState = this._rs;
      colorCommand.shaderProgram = this._sp;
      colorCommand.uniformMap = combine(this._uniforms, this.material._uniforms);
      colorCommand.executeInClosestFrustum = translucent;
    }

    var commandList = frameState.commandList;
    var passes = frameState.passes;

    if (passes.render) {
      colorCommand.boundingVolume = this._boundingSphere;
      colorCommand.debugShowBoundingVolume = this.debugShowBoundingVolume;
      colorCommand.modelMatrix = this._computedModelMatrix;
      colorCommand.pass = translucent ? Pass$1.TRANSLUCENT : Pass$1.OPAQUE;

      commandList.push(colorCommand);
    }

    if (passes.pick) {
      var pickCommand = this._pickCommand;

      if (!defined(this._pickId) || this._id !== this.id) {
        this._id = this.id;
        this._pickId = this._pickId && this._pickId.destroy();
        this._pickId = context.createPickId({
          primitive: this,
          id: this.id,
        });
      }

      // Recompile shader when material changes
      if (
        materialChanged ||
        lightingChanged ||
        !defined(this._pickSP) ||
        useLogDepthChanged
      ) {
        vs = new ShaderSource({
          sources: [EllipsoidVS],
        });
        fs = new ShaderSource({
          sources: [this.material.shaderSource, EllipsoidFS],
          pickColorQualifier: "uniform",
        });
        if (this.onlySunLighting) {
          fs.defines.push("ONLY_SUN_LIGHTING");
        }
        if (!translucent && context.fragmentDepth) {
          fs.defines.push("WRITE_DEPTH");
        }
        if (this._useLogDepth) {
          vs.defines.push("LOG_DEPTH");
          fs.defines.push("LOG_DEPTH");
          fs.sources.push(logDepthExtension);
        }

        this._pickSP = ShaderProgram.replaceCache({
          context: context,
          shaderProgram: this._pickSP,
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations$4,
        });

        pickCommand.vertexArray = this._va;
        pickCommand.renderState = this._rs;
        pickCommand.shaderProgram = this._pickSP;
        pickCommand.uniformMap = combine(
          combine(this._uniforms, this._pickUniforms),
          this.material._uniforms
        );
        pickCommand.executeInClosestFrustum = translucent;
      }

      pickCommand.boundingVolume = this._boundingSphere;
      pickCommand.modelMatrix = this._computedModelMatrix;
      pickCommand.pass = translucent ? Pass$1.TRANSLUCENT : Pass$1.OPAQUE;

      commandList.push(pickCommand);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see EllipsoidPrimitive#destroy
   */
  EllipsoidPrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * e = e && e.destroy();
   *
   * @see EllipsoidPrimitive#isDestroyed
   */
  EllipsoidPrimitive.prototype.destroy = function () {
    this._sp = this._sp && this._sp.destroy();
    this._pickSP = this._pickSP && this._pickSP.destroy();
    this._pickId = this._pickId && this._pickId.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var EllipsoidSurfaceAppearanceFS = "varying vec3 v_positionMC;\n\
varying vec3 v_positionEC;\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
czm_materialInput materialInput;\n\
vec3 normalEC = normalize(czm_normal3D * czm_geodeticSurfaceNormal(v_positionMC, vec3(0.0), vec3(1.0)));\n\
#ifdef FACE_FORWARD\n\
normalEC = faceforward(normalEC, vec3(0.0, 0.0, 1.0), -normalEC);\n\
#endif\n\
materialInput.s = v_st.s;\n\
materialInput.st = v_st;\n\
materialInput.str = vec3(v_st, 0.0);\n\
materialInput.normalEC = normalEC;\n\
materialInput.tangentToEyeMatrix = czm_eastNorthUpToEyeCoordinates(v_positionMC, materialInput.normalEC);\n\
vec3 positionToEyeEC = -v_positionEC;\n\
materialInput.positionToEyeEC = positionToEyeEC;\n\
czm_material material = czm_getMaterial(materialInput);\n\
#ifdef FLAT\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
#else\n\
gl_FragColor = czm_phong(normalize(positionToEyeEC), material, czm_lightDirectionEC);\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var EllipsoidSurfaceAppearanceVS = "attribute vec3 position3DHigh;\n\
attribute vec3 position3DLow;\n\
attribute vec2 st;\n\
attribute float batchId;\n\
varying vec3 v_positionMC;\n\
varying vec3 v_positionEC;\n\
varying vec2 v_st;\n\
void main()\n\
{\n\
vec4 p = czm_computePosition();\n\
v_positionMC = position3DHigh + position3DLow;\n\
v_positionEC = (czm_modelViewRelativeToEye * p).xyz;\n\
v_st = st;\n\
gl_Position = czm_modelViewProjectionRelativeToEye * p;\n\
}\n\
";

  /**
   * An appearance for geometry on the surface of the ellipsoid like {@link PolygonGeometry}
   * and {@link RectangleGeometry}, which supports all materials like {@link MaterialAppearance}
   * with {@link MaterialAppearance.MaterialSupport.ALL}.  However, this appearance requires
   * fewer vertex attributes since the fragment shader can procedurally compute <code>normal</code>,
   * <code>tangent</code>, and <code>bitangent</code>.
   *
   * @alias EllipsoidSurfaceAppearance
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.flat=false] When <code>true</code>, flat shading is used in the fragment shader, which means lighting is not taking into account.
   * @param {Boolean} [options.faceForward=options.aboveGround] When <code>true</code>, the fragment shader flips the surface normal as needed to ensure that the normal faces the viewer to avoid dark spots.  This is useful when both sides of a geometry should be shaded like {@link WallGeometry}.
   * @param {Boolean} [options.translucent=true] When <code>true</code>, the geometry is expected to appear translucent so {@link EllipsoidSurfaceAppearance#renderState} has alpha blending enabled.
   * @param {Boolean} [options.aboveGround=false] When <code>true</code>, the geometry is expected to be on the ellipsoid's surface - not at a constant height above it - so {@link EllipsoidSurfaceAppearance#renderState} has backface culling enabled.
   * @param {Material} [options.material=Material.ColorType] The material used to determine the fragment color.
   * @param {String} [options.vertexShaderSource] Optional GLSL vertex shader source to override the default vertex shader.
   * @param {String} [options.fragmentShaderSource] Optional GLSL fragment shader source to override the default fragment shader.
   * @param {Object} [options.renderState] Optional render state to override the default render state.
   *
   * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
   *
   * @example
   * var primitive = new Cesium.Primitive({
   *   geometryInstances : new Cesium.GeometryInstance({
   *     geometry : new Cesium.PolygonGeometry({
   *       vertexFormat : Cesium.EllipsoidSurfaceAppearance.VERTEX_FORMAT,
   *       // ...
   *     })
   *   }),
   *   appearance : new Cesium.EllipsoidSurfaceAppearance({
   *     material : Cesium.Material.fromType('Stripe')
   *   })
   * });
   */
  function EllipsoidSurfaceAppearance(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var translucent = defaultValue(options.translucent, true);
    var aboveGround = defaultValue(options.aboveGround, false);

    /**
     * The material used to determine the fragment color.  Unlike other {@link EllipsoidSurfaceAppearance}
     * properties, this is not read-only, so an appearance's material can change on the fly.
     *
     * @type Material
     *
     * @default {@link Material.ColorType}
     *
     * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
     */
    this.material = defined(options.material)
      ? options.material
      : Material.fromType(Material.ColorType);

    /**
     * When <code>true</code>, the geometry is expected to appear translucent.
     *
     * @type {Boolean}
     *
     * @default true
     */
    this.translucent = defaultValue(options.translucent, true);

    this._vertexShaderSource = defaultValue(
      options.vertexShaderSource,
      EllipsoidSurfaceAppearanceVS
    );
    this._fragmentShaderSource = defaultValue(
      options.fragmentShaderSource,
      EllipsoidSurfaceAppearanceFS
    );
    this._renderState = Appearance.getDefaultRenderState(
      translucent,
      !aboveGround,
      options.renderState
    );
    this._closed = false;

    // Non-derived members

    this._flat = defaultValue(options.flat, false);
    this._faceForward = defaultValue(options.faceForward, aboveGround);
    this._aboveGround = aboveGround;
  }

  Object.defineProperties(EllipsoidSurfaceAppearance.prototype, {
    /**
     * The GLSL source code for the vertex shader.
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    vertexShaderSource: {
      get: function () {
        return this._vertexShaderSource;
      },
    },

    /**
     * The GLSL source code for the fragment shader.  The full fragment shader
     * source is built procedurally taking into account {@link EllipsoidSurfaceAppearance#material},
     * {@link EllipsoidSurfaceAppearance#flat}, and {@link EllipsoidSurfaceAppearance#faceForward}.
     * Use {@link EllipsoidSurfaceAppearance#getFragmentShaderSource} to get the full source.
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {String}
     * @readonly
     */
    fragmentShaderSource: {
      get: function () {
        return this._fragmentShaderSource;
      },
    },

    /**
     * The WebGL fixed-function state to use when rendering the geometry.
     * <p>
     * The render state can be explicitly defined when constructing a {@link EllipsoidSurfaceAppearance}
     * instance, or it is set implicitly via {@link EllipsoidSurfaceAppearance#translucent}
     * and {@link EllipsoidSurfaceAppearance#aboveGround}.
     * </p>
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {Object}
     * @readonly
     */
    renderState: {
      get: function () {
        return this._renderState;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be closed so
     * {@link EllipsoidSurfaceAppearance#renderState} has backface culling enabled.
     * If the viewer enters the geometry, it will not be visible.
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    closed: {
      get: function () {
        return this._closed;
      },
    },

    /**
     * The {@link VertexFormat} that this appearance instance is compatible with.
     * A geometry can have more vertex attributes and still be compatible - at a
     * potential performance cost - but it can't have less.
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type VertexFormat
     * @readonly
     *
     * @default {@link EllipsoidSurfaceAppearance.VERTEX_FORMAT}
     */
    vertexFormat: {
      get: function () {
        return EllipsoidSurfaceAppearance.VERTEX_FORMAT;
      },
    },

    /**
     * When <code>true</code>, flat shading is used in the fragment shader,
     * which means lighting is not taking into account.
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    flat: {
      get: function () {
        return this._flat;
      },
    },

    /**
     * When <code>true</code>, the fragment shader flips the surface normal
     * as needed to ensure that the normal faces the viewer to avoid
     * dark spots.  This is useful when both sides of a geometry should be
     * shaded like {@link WallGeometry}.
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default true
     */
    faceForward: {
      get: function () {
        return this._faceForward;
      },
    },

    /**
     * When <code>true</code>, the geometry is expected to be on the ellipsoid's
     * surface - not at a constant height above it - so {@link EllipsoidSurfaceAppearance#renderState}
     * has backface culling enabled.
     *
     *
     * @memberof EllipsoidSurfaceAppearance.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @default false
     */
    aboveGround: {
      get: function () {
        return this._aboveGround;
      },
    },
  });

  /**
   * The {@link VertexFormat} that all {@link EllipsoidSurfaceAppearance} instances
   * are compatible with, which requires only <code>position</code> and <code>st</code>
   * attributes.  Other attributes are procedurally computed in the fragment shader.
   *
   * @type VertexFormat
   *
   * @constant
   */
  EllipsoidSurfaceAppearance.VERTEX_FORMAT = VertexFormat.POSITION_AND_ST;

  /**
   * Procedurally creates the full GLSL fragment shader source.  For {@link EllipsoidSurfaceAppearance},
   * this is derived from {@link EllipsoidSurfaceAppearance#fragmentShaderSource}, {@link EllipsoidSurfaceAppearance#flat},
   * and {@link EllipsoidSurfaceAppearance#faceForward}.
   *
   * @function
   *
   * @returns {String} The full GLSL fragment shader source.
   */
  EllipsoidSurfaceAppearance.prototype.getFragmentShaderSource =
    Appearance.prototype.getFragmentShaderSource;

  /**
   * Determines if the geometry is translucent based on {@link EllipsoidSurfaceAppearance#translucent} and {@link Material#isTranslucent}.
   *
   * @function
   *
   * @returns {Boolean} <code>true</code> if the appearance is translucent.
   */
  EllipsoidSurfaceAppearance.prototype.isTranslucent =
    Appearance.prototype.isTranslucent;

  /**
   * Creates a render state.  This is not the final render state instance; instead,
   * it can contain a subset of render state properties identical to the render state
   * created in the context.
   *
   * @function
   *
   * @returns {Object} The render state.
   */
  EllipsoidSurfaceAppearance.prototype.getRenderState =
    Appearance.prototype.getRenderState;

  /**
   * Blends the atmosphere to geometry far from the camera for horizon views. Allows for additional
   * performance improvements by rendering less geometry and dispatching less terrain requests.
   *
   * @alias Fog
   * @constructor
   */
  function Fog() {
    /**
     * <code>true</code> if fog is enabled, <code>false</code> otherwise.
     * @type {Boolean}
     * @default true
     */
    this.enabled = true;
    /**
     * A scalar that determines the density of the fog. Terrain that is in full fog are culled.
     * The density of the fog increases as this number approaches 1.0 and becomes less dense as it approaches zero.
     * The more dense the fog is, the more aggressively the terrain is culled. For example, if the camera is a height of
     * 1000.0m above the ellipsoid, increasing the value to 3.0e-3 will cause many tiles close to the viewer be culled.
     * Decreasing the value will push the fog further from the viewer, but decrease performance as more of the terrain is rendered.
     * @type {Number}
     * @default 2.0e-4
     */
    this.density = 2.0e-4;
    /**
     * A factor used to increase the screen space error of terrain tiles when they are partially in fog. The effect is to reduce
     * the number of terrain tiles requested for rendering. If set to zero, the feature will be disabled. If the value is increased
     * for mountainous regions, less tiles will need to be requested, but the terrain meshes near the horizon may be a noticeably
     * lower resolution. If the value is increased in a relatively flat area, there will be little noticeable change on the horizon.
     * @type {Number}
     * @default 2.0
     */
    this.screenSpaceErrorFactor = 2.0;
    /**
     * The minimum brightness of the fog color from lighting. A value of 0.0 can cause the fog to be completely black. A value of 1.0 will not affect
     * the brightness at all.
     * @type {Number}
     * @default 0.03
     */
    this.minimumBrightness = 0.03;
  }

  // These values were found by sampling the density at certain views and finding at what point culled tiles impacted the view at the horizon.
  var heightsTable = [
    359.393,
    800.749,
    1275.6501,
    2151.1192,
    3141.7763,
    4777.5198,
    6281.2493,
    12364.307,
    15900.765,
    49889.0549,
    78026.8259,
    99260.7344,
    120036.3873,
    151011.0158,
    156091.1953,
    203849.3112,
    274866.9803,
    319916.3149,
    493552.0528,
    628733.5874,
  ];
  var densityTable = [
    2.0e-5,
    2.0e-4,
    1.0e-4,
    7.0e-5,
    5.0e-5,
    4.0e-5,
    3.0e-5,
    1.9e-5,
    1.0e-5,
    8.5e-6,
    6.2e-6,
    5.8e-6,
    5.3e-6,
    5.2e-6,
    5.1e-6,
    4.2e-6,
    4.0e-6,
    3.4e-6,
    2.6e-6,
    2.2e-6,
  ];

  // Scale densities by 1e6 to bring lowest value to ~1. Prevents divide by zero.
  for (var i$3 = 0; i$3 < densityTable.length; ++i$3) {
    densityTable[i$3] *= 1.0e6;
  }
  // Change range to [0, 1].
  var tableStartDensity = densityTable[1];
  var tableEndDensity = densityTable[densityTable.length - 1];
  for (var j = 0; j < densityTable.length; ++j) {
    densityTable[j] =
      (densityTable[j] - tableEndDensity) / (tableStartDensity - tableEndDensity);
  }

  var tableLastIndex = 0;

  function findInterval(height) {
    var heights = heightsTable;
    var length = heights.length;

    if (height < heights[0]) {
      tableLastIndex = 0;
      return tableLastIndex;
    } else if (height > heights[length - 1]) {
      tableLastIndex = length - 2;
      return tableLastIndex;
    }

    // Take advantage of temporal coherence by checking current, next and previous intervals
    // for containment of time.
    if (height >= heights[tableLastIndex]) {
      if (tableLastIndex + 1 < length && height < heights[tableLastIndex + 1]) {
        return tableLastIndex;
      } else if (
        tableLastIndex + 2 < length &&
        height < heights[tableLastIndex + 2]
      ) {
        ++tableLastIndex;
        return tableLastIndex;
      }
    } else if (tableLastIndex - 1 >= 0 && height >= heights[tableLastIndex - 1]) {
      --tableLastIndex;
      return tableLastIndex;
    }

    // The above failed so do a linear search.
    var i;
    for (i = 0; i < length - 2; ++i) {
      if (height >= heights[i] && height < heights[i + 1]) {
        break;
      }
    }

    tableLastIndex = i;
    return tableLastIndex;
  }

  var scratchPositionNormal$1 = new Cartesian3();

  Fog.prototype.update = function (frameState) {
    var enabled = (frameState.fog.enabled = this.enabled);
    if (!enabled) {
      return;
    }

    var camera = frameState.camera;
    var positionCartographic = camera.positionCartographic;

    // Turn off fog in space.
    if (
      !defined(positionCartographic) ||
      positionCartographic.height > 800000.0 ||
      frameState.mode !== SceneMode$1.SCENE3D
    ) {
      frameState.fog.enabled = false;
      return;
    }

    var height = positionCartographic.height;
    var i = findInterval(height);
    var t = CesiumMath.clamp(
      (height - heightsTable[i]) / (heightsTable[i + 1] - heightsTable[i]),
      0.0,
      1.0
    );
    var density = CesiumMath.lerp(densityTable[i], densityTable[i + 1], t);

    // Again, scale value to be in the range of densityTable (prevents divide by zero) and change to new range.
    var startDensity = this.density * 1.0e6;
    var endDensity = (startDensity / tableStartDensity) * tableEndDensity;
    density = density * (startDensity - endDensity) * 1.0e-6;

    // Fade fog in as the camera tilts toward the horizon.
    var positionNormal = Cartesian3.normalize(
      camera.positionWC,
      scratchPositionNormal$1
    );
    var dot = Math.abs(Cartesian3.dot(camera.directionWC, positionNormal));
    density *= 1.0 - dot;

    frameState.fog.density = density;
    frameState.fog.sse = this.screenSpaceErrorFactor;
    frameState.fog.minimumBrightness = this.minimumBrightness;
  };

  /**
   * Monitors the frame rate (frames per second) in a {@link Scene} and raises an event if the frame rate is
   * lower than a threshold.  Later, if the frame rate returns to the required level, a separate event is raised.
   * To avoid creating multiple FrameRateMonitors for a single {@link Scene}, use {@link FrameRateMonitor.fromScene}
   * instead of constructing an instance explicitly.
   *
   * @alias FrameRateMonitor
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Scene} options.scene The Scene instance for which to monitor performance.
   * @param {Number} [options.samplingWindow=5.0] The length of the sliding window over which to compute the average frame rate, in seconds.
   * @param {Number} [options.quietPeriod=2.0] The length of time to wait at startup and each time the page becomes visible (i.e. when the user
   *        switches back to the tab) before starting to measure performance, in seconds.
   * @param {Number} [options.warmupPeriod=5.0] The length of the warmup period, in seconds.  During the warmup period, a separate
   *        (usually lower) frame rate is required.
   * @param {Number} [options.minimumFrameRateDuringWarmup=4] The minimum frames-per-second that are required for acceptable performance during
   *        the warmup period.  If the frame rate averages less than this during any samplingWindow during the warmupPeriod, the
   *        lowFrameRate event will be raised and the page will redirect to the redirectOnLowFrameRateUrl, if any.
   * @param {Number} [options.minimumFrameRateAfterWarmup=8] The minimum frames-per-second that are required for acceptable performance after
   *        the end of the warmup period.  If the frame rate averages less than this during any samplingWindow after the warmupPeriod, the
   *        lowFrameRate event will be raised and the page will redirect to the redirectOnLowFrameRateUrl, if any.
   */
  function FrameRateMonitor(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.scene)) {
      throw new DeveloperError("options.scene is required.");
    }
    //>>includeEnd('debug');

    this._scene = options.scene;

    /**
     * Gets or sets the length of the sliding window over which to compute the average frame rate, in seconds.
     * @type {Number}
     */
    this.samplingWindow = defaultValue(
      options.samplingWindow,
      FrameRateMonitor.defaultSettings.samplingWindow
    );

    /**
     * Gets or sets the length of time to wait at startup and each time the page becomes visible (i.e. when the user
     * switches back to the tab) before starting to measure performance, in seconds.
     * @type {Number}
     */
    this.quietPeriod = defaultValue(
      options.quietPeriod,
      FrameRateMonitor.defaultSettings.quietPeriod
    );

    /**
     * Gets or sets the length of the warmup period, in seconds.  During the warmup period, a separate
     * (usually lower) frame rate is required.
     * @type {Number}
     */
    this.warmupPeriod = defaultValue(
      options.warmupPeriod,
      FrameRateMonitor.defaultSettings.warmupPeriod
    );

    /**
     * Gets or sets the minimum frames-per-second that are required for acceptable performance during
     * the warmup period.  If the frame rate averages less than this during any <code>samplingWindow</code> during the <code>warmupPeriod</code>, the
     * <code>lowFrameRate</code> event will be raised and the page will redirect to the <code>redirectOnLowFrameRateUrl</code>, if any.
     * @type {Number}
     */
    this.minimumFrameRateDuringWarmup = defaultValue(
      options.minimumFrameRateDuringWarmup,
      FrameRateMonitor.defaultSettings.minimumFrameRateDuringWarmup
    );

    /**
     * Gets or sets the minimum frames-per-second that are required for acceptable performance after
     * the end of the warmup period.  If the frame rate averages less than this during any <code>samplingWindow</code> after the <code>warmupPeriod</code>, the
     * <code>lowFrameRate</code> event will be raised and the page will redirect to the <code>redirectOnLowFrameRateUrl</code>, if any.
     * @type {Number}
     */
    this.minimumFrameRateAfterWarmup = defaultValue(
      options.minimumFrameRateAfterWarmup,
      FrameRateMonitor.defaultSettings.minimumFrameRateAfterWarmup
    );

    this._lowFrameRate = new Event();
    this._nominalFrameRate = new Event();

    this._frameTimes = [];
    this._needsQuietPeriod = true;
    this._quietPeriodEndTime = 0.0;
    this._warmupPeriodEndTime = 0.0;
    this._frameRateIsLow = false;
    this._lastFramesPerSecond = undefined;
    this._pauseCount = 0;

    var that = this;
    this._preUpdateRemoveListener = this._scene.preUpdate.addEventListener(
      function (scene, time) {
        update$5(that);
      }
    );

    this._hiddenPropertyName =
      document.hidden !== undefined
        ? "hidden"
        : document.mozHidden !== undefined
        ? "mozHidden"
        : document.msHidden !== undefined
        ? "msHidden"
        : document.webkitHidden !== undefined
        ? "webkitHidden"
        : undefined;

    var visibilityChangeEventName =
      document.hidden !== undefined
        ? "visibilitychange"
        : document.mozHidden !== undefined
        ? "mozvisibilitychange"
        : document.msHidden !== undefined
        ? "msvisibilitychange"
        : document.webkitHidden !== undefined
        ? "webkitvisibilitychange"
        : undefined;

    function visibilityChangeListener() {
      visibilityChanged(that);
    }

    this._visibilityChangeRemoveListener = undefined;
    if (defined(visibilityChangeEventName)) {
      document.addEventListener(
        visibilityChangeEventName,
        visibilityChangeListener,
        false
      );

      this._visibilityChangeRemoveListener = function () {
        document.removeEventListener(
          visibilityChangeEventName,
          visibilityChangeListener,
          false
        );
      };
    }
  }

  /**
   * The default frame rate monitoring settings.  These settings are used when {@link FrameRateMonitor.fromScene}
   * needs to create a new frame rate monitor, and for any settings that are not passed to the
   * {@link FrameRateMonitor} constructor.
   *
   * @memberof FrameRateMonitor
   * @type {Object}
   */
  FrameRateMonitor.defaultSettings = {
    samplingWindow: 5.0,
    quietPeriod: 2.0,
    warmupPeriod: 5.0,
    minimumFrameRateDuringWarmup: 4,
    minimumFrameRateAfterWarmup: 8,
  };

  /**
   * Gets the {@link FrameRateMonitor} for a given scene.  If the scene does not yet have
   * a {@link FrameRateMonitor}, one is created with the {@link FrameRateMonitor.defaultSettings}.
   *
   * @param {Scene} scene The scene for which to get the {@link FrameRateMonitor}.
   * @returns {FrameRateMonitor} The scene's {@link FrameRateMonitor}.
   */
  FrameRateMonitor.fromScene = function (scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    if (
      !defined(scene._frameRateMonitor) ||
      scene._frameRateMonitor.isDestroyed()
    ) {
      scene._frameRateMonitor = new FrameRateMonitor({
        scene: scene,
      });
    }

    return scene._frameRateMonitor;
  };

  Object.defineProperties(FrameRateMonitor.prototype, {
    /**
     * Gets the {@link Scene} instance for which to monitor performance.
     * @memberof FrameRateMonitor.prototype
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets the event that is raised when a low frame rate is detected.  The function will be passed
     * the {@link Scene} instance as its first parameter and the average number of frames per second
     * over the sampling window as its second parameter.
     * @memberof FrameRateMonitor.prototype
     * @type {Event}
     */
    lowFrameRate: {
      get: function () {
        return this._lowFrameRate;
      },
    },

    /**
     * Gets the event that is raised when the frame rate returns to a normal level after having been low.
     * The function will be passed the {@link Scene} instance as its first parameter and the average
     * number of frames per second over the sampling window as its second parameter.
     * @memberof FrameRateMonitor.prototype
     * @type {Event}
     */
    nominalFrameRate: {
      get: function () {
        return this._nominalFrameRate;
      },
    },

    /**
     * Gets the most recently computed average frames-per-second over the last <code>samplingWindow</code>.
     * This property may be undefined if the frame rate has not been computed.
     * @memberof FrameRateMonitor.prototype
     * @type {Number}
     */
    lastFramesPerSecond: {
      get: function () {
        return this._lastFramesPerSecond;
      },
    },
  });

  /**
   * Pauses monitoring of the frame rate.  To resume monitoring, {@link FrameRateMonitor#unpause}
   * must be called once for each time this function is called.
   * @memberof FrameRateMonitor
   */
  FrameRateMonitor.prototype.pause = function () {
    ++this._pauseCount;
    if (this._pauseCount === 1) {
      this._frameTimes.length = 0;
      this._lastFramesPerSecond = undefined;
    }
  };

  /**
   * Resumes monitoring of the frame rate.  If {@link FrameRateMonitor#pause} was called
   * multiple times, this function must be called the same number of times in order to
   * actually resume monitoring.
   * @memberof FrameRateMonitor
   */
  FrameRateMonitor.prototype.unpause = function () {
    --this._pauseCount;
    if (this._pauseCount <= 0) {
      this._pauseCount = 0;
      this._needsQuietPeriod = true;
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @memberof FrameRateMonitor
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see FrameRateMonitor#destroy
   */
  FrameRateMonitor.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Unsubscribes this instance from all events it is listening to.
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @memberof FrameRateMonitor
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see FrameRateMonitor#isDestroyed
   */
  FrameRateMonitor.prototype.destroy = function () {
    this._preUpdateRemoveListener();

    if (defined(this._visibilityChangeRemoveListener)) {
      this._visibilityChangeRemoveListener();
    }

    return destroyObject(this);
  };

  function update$5(monitor, time) {
    if (monitor._pauseCount > 0) {
      return;
    }

    var timeStamp = getTimestamp$1();

    if (monitor._needsQuietPeriod) {
      monitor._needsQuietPeriod = false;
      monitor._frameTimes.length = 0;
      monitor._quietPeriodEndTime =
        timeStamp + monitor.quietPeriod / TimeConstants$1.SECONDS_PER_MILLISECOND;
      monitor._warmupPeriodEndTime =
        monitor._quietPeriodEndTime +
        (monitor.warmupPeriod + monitor.samplingWindow) /
          TimeConstants$1.SECONDS_PER_MILLISECOND;
    } else if (timeStamp >= monitor._quietPeriodEndTime) {
      monitor._frameTimes.push(timeStamp);

      var beginningOfWindow =
        timeStamp -
        monitor.samplingWindow / TimeConstants$1.SECONDS_PER_MILLISECOND;

      if (
        monitor._frameTimes.length >= 2 &&
        monitor._frameTimes[0] <= beginningOfWindow
      ) {
        while (
          monitor._frameTimes.length >= 2 &&
          monitor._frameTimes[1] < beginningOfWindow
        ) {
          monitor._frameTimes.shift();
        }

        var averageTimeBetweenFrames =
          (timeStamp - monitor._frameTimes[0]) / (monitor._frameTimes.length - 1);

        monitor._lastFramesPerSecond = 1000.0 / averageTimeBetweenFrames;

        var maximumFrameTime =
          1000.0 /
          (timeStamp > monitor._warmupPeriodEndTime
            ? monitor.minimumFrameRateAfterWarmup
            : monitor.minimumFrameRateDuringWarmup);
        if (averageTimeBetweenFrames > maximumFrameTime) {
          if (!monitor._frameRateIsLow) {
            monitor._frameRateIsLow = true;
            monitor._needsQuietPeriod = true;
            monitor.lowFrameRate.raiseEvent(
              monitor.scene,
              monitor._lastFramesPerSecond
            );
          }
        } else if (monitor._frameRateIsLow) {
          monitor._frameRateIsLow = false;
          monitor._needsQuietPeriod = true;
          monitor.nominalFrameRate.raiseEvent(
            monitor.scene,
            monitor._lastFramesPerSecond
          );
        }
      }
    }
  }

  function visibilityChanged(monitor) {
    if (document[monitor._hiddenPropertyName]) {
      monitor.pause();
    } else {
      monitor.unpause();
    }
  }

  /**
   * State information about the current frame.  An instance of this class
   * is provided to update functions.
   *
   * @param {Context} context The rendering context
   * @param {CreditDisplay} creditDisplay Handles adding and removing credits from an HTML element
   * @param {JobScheduler} jobScheduler The job scheduler
   *
   * @alias FrameState
   * @constructor
   *
   * @private
   */
  function FrameState(context, creditDisplay, jobScheduler) {
    /**
     * The rendering context.
     *
     * @type {Context}
     */
    this.context = context;

    /**
     * An array of rendering commands.
     *
     * @type {DrawCommand[]}
     */
    this.commandList = [];

    /**
     * An array of shadow maps.
     * @type {ShadowMap[]}
     */
    this.shadowMaps = [];

    /**
     * The BRDF look up texture generator used for image-based lighting for PBR models
     * @type {BrdfLutGenerator}
     */
    this.brdfLutGenerator = undefined;

    /**
     * The environment map used for image-based lighting for PBR models
     * @type {CubeMap}
     */
    this.environmentMap = undefined;

    /**
     * The spherical harmonic coefficients used for image-based lighting for PBR models.
     * @type {Cartesian3[]}
     */
    this.sphericalHarmonicCoefficients = undefined;

    /**
     * The specular environment atlas used for image-based lighting for PBR models.
     * @type {Texture}
     */
    this.specularEnvironmentMaps = undefined;

    /**
     * The maximum level-of-detail of the specular environment atlas used for image-based lighting for PBR models.
     * @type {Number}
     */
    this.specularEnvironmentMapsMaximumLOD = undefined;

    /**
     * The current mode of the scene.
     *
     * @type {SceneMode}
     * @default {@link SceneMode.SCENE3D}
     */
    this.mode = SceneMode$1.SCENE3D;

    /**
     * The current morph transition time between 2D/Columbus View and 3D,
     * with 0.0 being 2D or Columbus View and 1.0 being 3D.
     *
     * @type {Number}
     */
    this.morphTime = SceneMode$1.getMorphTime(SceneMode$1.SCENE3D);

    /**
     * The current frame number.
     *
     * @type {Number}
     * @default 0
     */
    this.frameNumber = 0;

    /**
     * <code>true</code> if a new frame has been issued and the frame number has been updated.
     *
     * @type {Boolean}
     * @default false
     */
    this.newFrame = false;

    /**
     * The scene's current time.
     *
     * @type {JulianDate}
     * @default undefined
     */
    this.time = undefined;

    /**
     * The job scheduler.
     *
     * @type {JobScheduler}
     */
    this.jobScheduler = jobScheduler;

    /**
     * The map projection to use in 2D and Columbus View modes.
     *
     * @type {MapProjection}
     * @default undefined
     */
    this.mapProjection = undefined;

    /**
     * The current camera.
     *
     * @type {Camera}
     * @default undefined
     */
    this.camera = undefined;

    /**
     * Whether the camera is underground.
     *
     * @type {Boolean}
     * @default false
     */
    this.cameraUnderground = false;

    /**
     * The {@link GlobeTranslucencyState} object used by the scene.
     *
     * @type {GlobeTranslucencyState}
     * @default undefined
     */
    this.globeTranslucencyState = undefined;

    /**
     * The culling volume.
     *
     * @type {CullingVolume}
     * @default undefined
     */
    this.cullingVolume = undefined;

    /**
     * The current occluder.
     *
     * @type {Occluder}
     * @default undefined
     */
    this.occluder = undefined;

    /**
     * The maximum screen-space error used to drive level-of-detail refinement.  Higher
     * values will provide better performance but lower visual quality.
     *
     * @type {Number}
     * @default 2
     */
    this.maximumScreenSpaceError = undefined;

    /**
     * Ratio between a pixel and a density-independent pixel. Provides a standard unit of
     * measure for real pixel measurements appropriate to a particular device.
     *
     * @type {Number}
     * @default 1.0
     */
    this.pixelRatio = 1.0;

    /**
     * @typedef FrameState.Passes
     * @type {Object}
     * @property {Boolean} render <code>true</code> if the primitive should update for a render pass, <code>false</code> otherwise.
     * @property {Boolean} pick <code>true</code> if the primitive should update for a picking pass, <code>false</code> otherwise.
     * @property {Boolean} depth <code>true</code> if the primitive should update for a depth only pass, <code>false</code> otherwise.
     * @property {Boolean} postProcess <code>true</code> if the primitive should update for a per-feature post-process pass, <code>false</code> otherwise.
     * @property {Boolean} offscreen <code>true</code> if the primitive should update for an offscreen pass, <code>false</code> otherwise.
     */

    /**
     * @type {FrameState.Passes}
     */
    this.passes = {
      /**
       * @default false
       */
      render: false,
      /**
       * @default false
       */
      pick: false,
      /**
       * @default false
       */
      depth: false,
      /**
       * @default false
       */
      postProcess: false,
      /**
       * @default false
       */
      offscreen: false,
    };

    /**
     * The credit display.
     *
     * @type {CreditDisplay}
     */
    this.creditDisplay = creditDisplay;

    /**
     * An array of functions to be called at the end of the frame.  This array
     * will be cleared after each frame.
     * <p>
     * This allows queueing up events in <code>update</code> functions and
     * firing them at a time when the subscribers are free to change the
     * scene state, e.g., manipulate the camera, instead of firing events
     * directly in <code>update</code> functions.
     * </p>
     *
     * @type {FrameState.AfterRenderCallback[]}
     *
     * @example
     * frameState.afterRender.push(function() {
     *   // take some action, raise an event, etc.
     * });
     */
    this.afterRender = [];

    /**
     * Gets whether or not to optimized for 3D only.
     *
     * @type {Boolean}
     * @default false
     */
    this.scene3DOnly = false;

    /**
     * @typedef FrameState.Fog
     * @type {Object}
     * @property {Boolean} enabled <code>true</code> if fog is enabled, <code>false</code> otherwise.
     * @property {Number} density A positive number used to mix the color and fog color based on camera distance.
     * @property {Number} sse A scalar used to modify the screen space error of geometry partially in fog.
     * @property {Number} minimumBrightness The minimum brightness of terrain with fog applied.
     */

    /**
     * @type {FrameState.Fog}
     */

    this.fog = {
      /**
       * @default false
       */
      enabled: false,
      density: undefined,
      sse: undefined,
      minimumBrightness: undefined,
    };

    /**
     * A scalar used to exaggerate the terrain.
     * @type {Number}
     * @default 1.0
     */
    this.terrainExaggeration = 1.0;

    /**
     * @typedef FrameState.ShadowState
     * @type {Object}
     * @property {Boolean} shadowsEnabled Whether there are any active shadow maps this frame.
     * @property {Boolean} lightShadowsEnabled Whether there are any active shadow maps that originate from light sources. Does not include shadow maps that are used for analytical purposes.
     * @property {ShadowMap[]} shadowMaps All shadow maps that are enabled this frame.
     * @property {ShadowMap[]} lightShadowMaps Shadow maps that originate from light sources. Does not include shadow maps that are used for analytical purposes. Only these shadow maps will be used to generate receive shadows shaders.
     * @property {Number} nearPlane The near plane of the scene's frustum commands. Used for fitting cascaded shadow maps.
     * @property {Number} farPlane The far plane of the scene's frustum commands. Used for fitting cascaded shadow maps.
     * @property {Number} closestObjectSize The size of the bounding volume that is closest to the camera. This is used to place more shadow detail near the object.
     * @property {Number} lastDirtyTime The time when a shadow map was last dirty
     * @property {Boolean} outOfView Whether the shadows maps are out of view this frame
     */

    /**
     * @type {FrameState.ShadowState}
     */

    this.shadowState = {
      /**
       * @default true
       */
      shadowsEnabled: true,
      shadowMaps: [],
      lightShadowMaps: [],
      /**
       * @default 1.0
       */
      nearPlane: 1.0,
      /**
       * @default 5000.0
       */
      farPlane: 5000.0,
      /**
       * @default 1000.0
       */
      closestObjectSize: 1000.0,
      /**
       * @default 0
       */
      lastDirtyTime: 0,
      /**
       * @default true
       */
      outOfView: true,
    };

    /**
     * The position of the splitter to use when rendering imagery layers on either side of a splitter.
     * This value should be between 0.0 and 1.0 with 0 being the far left of the viewport and 1 being the far right of the viewport.
     * @type {Number}
     * @default 0.0
     */
    this.imagerySplitPosition = 0.0;

    /**
     * Distances to the near and far planes of the camera frustums
     * @type {Number[]}
     * @default []
     */
    this.frustumSplits = [];

    /**
     * The current scene background color
     *
     * @type {Color}
     */
    this.backgroundColor = undefined;

    /**
     * The light used to shade the scene.
     *
     * @type {Light}
     */
    this.light = undefined;

    /**
     * The distance from the camera at which to disable the depth test of billboards, labels and points
     * to, for example, prevent clipping against terrain. When set to zero, the depth test should always
     * be applied. When less than zero, the depth test should never be applied.
     * @type {Number}
     */
    this.minimumDisableDepthTestDistance = undefined;

    /**
     * When <code>false</code>, 3D Tiles will render normally. When <code>true</code>, classified 3D Tile geometry will render normally and
     * unclassified 3D Tile geometry will render with the color multiplied with {@link FrameState#invertClassificationColor}.
     * @type {Boolean}
     * @default false
     */
    this.invertClassification = false;

    /**
     * The highlight color of unclassified 3D Tile geometry when {@link FrameState#invertClassification} is <code>true</code>.
     * @type {Color}
     */
    this.invertClassificationColor = undefined;

    /**
     * Whether or not the scene uses a logarithmic depth buffer.
     *
     * @type {Boolean}
     * @default false
     */
    this.useLogDepth = false;

    /**
     * Additional state used to update 3D Tilesets.
     *
     * @type {Cesium3DTilePassState}
     */
    this.tilesetPassState = undefined;

    /**
     * The minimum terrain height out of all rendered terrain tiles. Used to improve culling for objects underneath the ellipsoid but above terrain.
     *
     * @type {Number}
     * @default 0.0
     */
    this.minimumTerrainHeight = 0.0;
  }

  /**
   * Defines a list of commands whose geometry are bound by near and far distances from the camera.
   * @alias FrustumCommands
   * @constructor
   *
   * @param {Number} [near=0.0] The lower bound or closest distance from the camera.
   * @param {Number} [far=0.0] The upper bound or farthest distance from the camera.
   *
   * @private
   */
  function FrustumCommands(near, far) {
    this.near = defaultValue(near, 0.0);
    this.far = defaultValue(far, 0.0);

    var numPasses = Pass$1.NUMBER_OF_PASSES;
    var commands = new Array(numPasses);
    var indices = new Array(numPasses);

    for (var i = 0; i < numPasses; ++i) {
      commands[i] = [];
      indices[i] = 0;
    }

    this.commands = commands;
    this.indices = indices;
  }

  /**
   * Describes the format in which to request GetFeatureInfo from a Web Map Service (WMS) server.
   *
   * @alias GetFeatureInfoFormat
   * @constructor
   *
   * @param {String} type The type of response to expect from a GetFeatureInfo request.  Valid
   *        values are 'json', 'xml', 'html', or 'text'.
   * @param {String} [format] The info format to request from the WMS server.  This is usually a
   *        MIME type such as 'application/json' or text/xml'.  If this parameter is not specified, the provider will request 'json'
   *        using 'application/json', 'xml' using 'text/xml', 'html' using 'text/html', and 'text' using 'text/plain'.
   * @param {Function} [callback] A function to invoke with the GetFeatureInfo response from the WMS server
   *        in order to produce an array of picked {@link ImageryLayerFeatureInfo} instances.  If this parameter is not specified,
   *        a default function for the type of response is used.
   */
  function GetFeatureInfoFormat(type, format, callback) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(type)) {
      throw new DeveloperError("type is required.");
    }
    //>>includeEnd('debug');

    this.type = type;

    if (!defined(format)) {
      if (type === "json") {
        format = "application/json";
      } else if (type === "xml") {
        format = "text/xml";
      } else if (type === "html") {
        format = "text/html";
      } else if (type === "text") {
        format = "text/plain";
      }
      //>>includeStart('debug', pragmas.debug);
      else {
        throw new DeveloperError(
          'format is required when type is not "json", "xml", "html", or "text".'
        );
      }
      //>>includeEnd('debug');
    }

    this.format = format;

    if (!defined(callback)) {
      if (type === "json") {
        callback = geoJsonToFeatureInfo;
      } else if (type === "xml") {
        callback = xmlToFeatureInfo;
      } else if (type === "html") {
        callback = textToFeatureInfo;
      } else if (type === "text") {
        callback = textToFeatureInfo;
      }
      //>>includeStart('debug', pragmas.debug);
      else {
        throw new DeveloperError(
          'callback is required when type is not "json", "xml", "html", or "text".'
        );
      }
      //>>includeEnd('debug');
    }

    this.callback = callback;
  }

  function geoJsonToFeatureInfo(json) {
    var result = [];

    var features = json.features;
    for (var i = 0; i < features.length; ++i) {
      var feature = features[i];

      var featureInfo = new ImageryLayerFeatureInfo();
      featureInfo.data = feature;
      featureInfo.properties = feature.properties;
      featureInfo.configureNameFromProperties(feature.properties);
      featureInfo.configureDescriptionFromProperties(feature.properties);

      // If this is a point feature, use the coordinates of the point.
      if (defined(feature.geometry) && feature.geometry.type === "Point") {
        var longitude = feature.geometry.coordinates[0];
        var latitude = feature.geometry.coordinates[1];
        featureInfo.position = Cartographic.fromDegrees(longitude, latitude);
      }

      result.push(featureInfo);
    }

    return result;
  }

  var mapInfoMxpNamespace = "http://www.mapinfo.com/mxp";
  var esriWmsNamespace = "http://www.esri.com/wms";
  var wfsNamespace = "http://www.opengis.net/wfs";
  var gmlNamespace = "http://www.opengis.net/gml";

  function xmlToFeatureInfo(xml) {
    var documentElement = xml.documentElement;
    if (
      documentElement.localName === "MultiFeatureCollection" &&
      documentElement.namespaceURI === mapInfoMxpNamespace
    ) {
      // This looks like a MapInfo MXP response
      return mapInfoXmlToFeatureInfo(xml);
    } else if (
      documentElement.localName === "FeatureInfoResponse" &&
      documentElement.namespaceURI === esriWmsNamespace
    ) {
      // This looks like an Esri WMS response
      return esriXmlToFeatureInfo(xml);
    } else if (
      documentElement.localName === "FeatureCollection" &&
      documentElement.namespaceURI === wfsNamespace
    ) {
      // This looks like a WFS/GML response.
      return gmlToFeatureInfo(xml);
    } else if (documentElement.localName === "ServiceExceptionReport") {
      // This looks like a WMS server error, so no features picked.
      throw new RuntimeError(
        new XMLSerializer().serializeToString(documentElement)
      );
    } else if (documentElement.localName === "msGMLOutput") {
      return msGmlToFeatureInfo(xml);
    } else {
      // Unknown response type, so just dump the XML itself into the description.
      return unknownXmlToFeatureInfo(xml);
    }
  }

  function mapInfoXmlToFeatureInfo(xml) {
    var result = [];

    var multiFeatureCollection = xml.documentElement;

    var features = multiFeatureCollection.getElementsByTagNameNS(
      mapInfoMxpNamespace,
      "Feature"
    );
    for (var featureIndex = 0; featureIndex < features.length; ++featureIndex) {
      var feature = features[featureIndex];

      var properties = {};

      var propertyElements = feature.getElementsByTagNameNS(
        mapInfoMxpNamespace,
        "Val"
      );
      for (
        var propertyIndex = 0;
        propertyIndex < propertyElements.length;
        ++propertyIndex
      ) {
        var propertyElement = propertyElements[propertyIndex];
        if (propertyElement.hasAttribute("ref")) {
          var name = propertyElement.getAttribute("ref");
          var value = propertyElement.textContent.trim();
          properties[name] = value;
        }
      }

      var featureInfo = new ImageryLayerFeatureInfo();
      featureInfo.data = feature;
      featureInfo.properties = properties;
      featureInfo.configureNameFromProperties(properties);
      featureInfo.configureDescriptionFromProperties(properties);
      result.push(featureInfo);
    }

    return result;
  }

  function esriXmlToFeatureInfo(xml) {
    var featureInfoResponse = xml.documentElement;
    var result = [];
    var properties;

    var features = featureInfoResponse.getElementsByTagNameNS("*", "FIELDS");
    if (features.length > 0) {
      // Standard esri format
      for (var featureIndex = 0; featureIndex < features.length; ++featureIndex) {
        var feature = features[featureIndex];

        properties = {};

        var propertyAttributes = feature.attributes;
        for (
          var attributeIndex = 0;
          attributeIndex < propertyAttributes.length;
          ++attributeIndex
        ) {
          var attribute = propertyAttributes[attributeIndex];
          properties[attribute.name] = attribute.value;
        }

        result.push(
          imageryLayerFeatureInfoFromDataAndProperties(feature, properties)
        );
      }
    } else {
      // Thredds format -- looks like esri, but instead of containing FIELDS, contains FeatureInfo element
      var featureInfoElements = featureInfoResponse.getElementsByTagNameNS(
        "*",
        "FeatureInfo"
      );
      for (
        var featureInfoElementIndex = 0;
        featureInfoElementIndex < featureInfoElements.length;
        ++featureInfoElementIndex
      ) {
        var featureInfoElement = featureInfoElements[featureInfoElementIndex];

        properties = {};

        // node.children is not supported in IE9-11, so use childNodes and check that child.nodeType is an element
        var featureInfoChildren = featureInfoElement.childNodes;
        for (
          var childIndex = 0;
          childIndex < featureInfoChildren.length;
          ++childIndex
        ) {
          var child = featureInfoChildren[childIndex];
          if (child.nodeType === Node.ELEMENT_NODE) {
            properties[child.localName] = child.textContent;
          }
        }

        result.push(
          imageryLayerFeatureInfoFromDataAndProperties(
            featureInfoElement,
            properties
          )
        );
      }
    }

    return result;
  }

  function gmlToFeatureInfo(xml) {
    var result = [];

    var featureCollection = xml.documentElement;

    var featureMembers = featureCollection.getElementsByTagNameNS(
      gmlNamespace,
      "featureMember"
    );
    for (
      var featureIndex = 0;
      featureIndex < featureMembers.length;
      ++featureIndex
    ) {
      var featureMember = featureMembers[featureIndex];

      var properties = {};
      getGmlPropertiesRecursively(featureMember, properties);
      result.push(
        imageryLayerFeatureInfoFromDataAndProperties(featureMember, properties)
      );
    }

    return result;
  }

  // msGmlToFeatureInfo is similar to gmlToFeatureInfo, but assumes different XML structure
  // eg. <msGMLOutput> <ABC_layer> <ABC_feature> <foo>bar</foo> ... </ABC_feature> </ABC_layer> </msGMLOutput>

  function msGmlToFeatureInfo(xml) {
    var result = [];

    // Find the first child. Except for IE, this would work:
    // var layer = xml.documentElement.children[0];
    var layer;
    var children = xml.documentElement.childNodes;
    for (var i = 0; i < children.length; i++) {
      if (children[i].nodeType === Node.ELEMENT_NODE) {
        layer = children[i];
        break;
      }
    }
    if (!defined(layer)) {
      throw new RuntimeError(
        "Unable to find first child of the feature info xml document"
      );
    }
    var featureMembers = layer.childNodes;
    for (
      var featureIndex = 0;
      featureIndex < featureMembers.length;
      ++featureIndex
    ) {
      var featureMember = featureMembers[featureIndex];
      if (featureMember.nodeType === Node.ELEMENT_NODE) {
        var properties = {};
        getGmlPropertiesRecursively(featureMember, properties);
        result.push(
          imageryLayerFeatureInfoFromDataAndProperties(featureMember, properties)
        );
      }
    }

    return result;
  }

  function getGmlPropertiesRecursively(gmlNode, properties) {
    var isSingleValue = true;

    for (var i = 0; i < gmlNode.childNodes.length; ++i) {
      var child = gmlNode.childNodes[i];

      if (child.nodeType === Node.ELEMENT_NODE) {
        isSingleValue = false;
      }

      if (
        child.localName === "Point" ||
        child.localName === "LineString" ||
        child.localName === "Polygon" ||
        child.localName === "boundedBy"
      ) {
        continue;
      }

      if (
        child.hasChildNodes() &&
        getGmlPropertiesRecursively(child, properties)
      ) {
        properties[child.localName] = child.textContent;
      }
    }

    return isSingleValue;
  }

  function imageryLayerFeatureInfoFromDataAndProperties(data, properties) {
    var featureInfo = new ImageryLayerFeatureInfo();
    featureInfo.data = data;
    featureInfo.properties = properties;
    featureInfo.configureNameFromProperties(properties);
    featureInfo.configureDescriptionFromProperties(properties);
    return featureInfo;
  }

  function unknownXmlToFeatureInfo(xml) {
    var xmlText = new XMLSerializer().serializeToString(xml);

    var element = document.createElement("div");
    var pre = document.createElement("pre");
    pre.textContent = xmlText;
    element.appendChild(pre);

    var featureInfo = new ImageryLayerFeatureInfo();
    featureInfo.data = xml;
    featureInfo.description = element.innerHTML;
    return [featureInfo];
  }

  var emptyBodyRegex = /<body>\s*<\/body>/im;
  var wmsServiceExceptionReportRegex = /<ServiceExceptionReport([\s\S]*)<\/ServiceExceptionReport>/im;
  var titleRegex = /<title>([\s\S]*)<\/title>/im;

  function textToFeatureInfo(text) {
    // If the text is HTML and it has an empty body tag, assume it means no features were found.
    if (emptyBodyRegex.test(text)) {
      return undefined;
    }

    // If this is a WMS exception report, treat it as "no features found" rather than showing
    // bogus feature info.
    if (wmsServiceExceptionReportRegex.test(text)) {
      return undefined;
    }

    // If the text has a <title> element, use it as the name.
    var name;
    var title = titleRegex.exec(text);
    if (title && title.length > 1) {
      name = title[1];
    }

    var featureInfo = new ImageryLayerFeatureInfo();
    featureInfo.name = name;
    featureInfo.description = text;
    featureInfo.data = text;
    return [featureInfo];
  }

  //This file is automatically rebuilt by the Cesium build process.
  var GlobeFS = "uniform vec4 u_initialColor;\n\
#if TEXTURE_UNITS > 0\n\
uniform sampler2D u_dayTextures[TEXTURE_UNITS];\n\
uniform vec4 u_dayTextureTranslationAndScale[TEXTURE_UNITS];\n\
uniform bool u_dayTextureUseWebMercatorT[TEXTURE_UNITS];\n\
#ifdef APPLY_ALPHA\n\
uniform float u_dayTextureAlpha[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_DAY_NIGHT_ALPHA\n\
uniform float u_dayTextureNightAlpha[TEXTURE_UNITS];\n\
uniform float u_dayTextureDayAlpha[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_SPLIT\n\
uniform float u_dayTextureSplit[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_BRIGHTNESS\n\
uniform float u_dayTextureBrightness[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_CONTRAST\n\
uniform float u_dayTextureContrast[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_HUE\n\
uniform float u_dayTextureHue[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_SATURATION\n\
uniform float u_dayTextureSaturation[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_GAMMA\n\
uniform float u_dayTextureOneOverGamma[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_IMAGERY_CUTOUT\n\
uniform vec4 u_dayTextureCutoutRectangles[TEXTURE_UNITS];\n\
#endif\n\
#ifdef APPLY_COLOR_TO_ALPHA\n\
uniform vec4 u_colorsToAlpha[TEXTURE_UNITS];\n\
#endif\n\
uniform vec4 u_dayTextureTexCoordsRectangle[TEXTURE_UNITS];\n\
#endif\n\
#ifdef SHOW_REFLECTIVE_OCEAN\n\
uniform sampler2D u_waterMask;\n\
uniform vec4 u_waterMaskTranslationAndScale;\n\
uniform float u_zoomedOutOceanSpecularIntensity;\n\
#endif\n\
#ifdef SHOW_OCEAN_WAVES\n\
uniform sampler2D u_oceanNormalMap;\n\
#endif\n\
#if defined(ENABLE_DAYNIGHT_SHADING) || defined(GROUND_ATMOSPHERE)\n\
uniform vec2 u_lightingFadeDistance;\n\
#endif\n\
#ifdef TILE_LIMIT_RECTANGLE\n\
uniform vec4 u_cartographicLimitRectangle;\n\
#endif\n\
#ifdef GROUND_ATMOSPHERE\n\
uniform vec2 u_nightFadeDistance;\n\
#endif\n\
#ifdef ENABLE_CLIPPING_PLANES\n\
uniform highp sampler2D u_clippingPlanes;\n\
uniform mat4 u_clippingPlanesMatrix;\n\
uniform vec4 u_clippingPlanesEdgeStyle;\n\
#endif\n\
#if defined(FOG) && defined(DYNAMIC_ATMOSPHERE_LIGHTING) && (defined(ENABLE_VERTEX_LIGHTING) || defined(ENABLE_DAYNIGHT_SHADING))\n\
uniform float u_minimumBrightness;\n\
#endif\n\
#ifdef COLOR_CORRECT\n\
uniform vec3 u_hsbShift;\n\
#endif\n\
#ifdef HIGHLIGHT_FILL_TILE\n\
uniform vec4 u_fillHighlightColor;\n\
#endif\n\
#ifdef TRANSLUCENT\n\
uniform vec4 u_frontFaceAlphaByDistance;\n\
uniform vec4 u_backFaceAlphaByDistance;\n\
uniform vec4 u_translucencyRectangle;\n\
#endif\n\
#ifdef UNDERGROUND_COLOR\n\
uniform vec4 u_undergroundColor;\n\
uniform vec4 u_undergroundColorAlphaByDistance;\n\
#endif\n\
varying vec3 v_positionMC;\n\
varying vec3 v_positionEC;\n\
varying vec3 v_textureCoordinates;\n\
varying vec3 v_normalMC;\n\
varying vec3 v_normalEC;\n\
#ifdef APPLY_MATERIAL\n\
varying float v_height;\n\
varying float v_slope;\n\
varying float v_aspect;\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE) || defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT)\n\
varying float v_distance;\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE)\n\
varying vec3 v_fogRayleighColor;\n\
varying vec3 v_fogMieColor;\n\
#endif\n\
#ifdef GROUND_ATMOSPHERE\n\
varying vec3 v_rayleighColor;\n\
varying vec3 v_mieColor;\n\
#endif\n\
#if defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT)\n\
float interpolateByDistance(vec4 nearFarScalar, float distance)\n\
{\n\
float startDistance = nearFarScalar.x;\n\
float startValue = nearFarScalar.y;\n\
float endDistance = nearFarScalar.z;\n\
float endValue = nearFarScalar.w;\n\
float t = clamp((distance - startDistance) / (endDistance - startDistance), 0.0, 1.0);\n\
return mix(startValue, endValue, t);\n\
}\n\
#endif\n\
#if defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT) || defined(APPLY_MATERIAL)\n\
vec4 alphaBlend(vec4 sourceColor, vec4 destinationColor)\n\
{\n\
return sourceColor * vec4(sourceColor.aaa, 1.0) + destinationColor * (1.0 - sourceColor.a);\n\
}\n\
#endif\n\
#ifdef TRANSLUCENT\n\
bool inTranslucencyRectangle()\n\
{\n\
return\n\
v_textureCoordinates.x > u_translucencyRectangle.x &&\n\
v_textureCoordinates.x < u_translucencyRectangle.z &&\n\
v_textureCoordinates.y > u_translucencyRectangle.y &&\n\
v_textureCoordinates.y < u_translucencyRectangle.w;\n\
}\n\
#endif\n\
vec4 sampleAndBlend(\n\
vec4 previousColor,\n\
sampler2D textureToSample,\n\
vec2 tileTextureCoordinates,\n\
vec4 textureCoordinateRectangle,\n\
vec4 textureCoordinateTranslationAndScale,\n\
float textureAlpha,\n\
float textureNightAlpha,\n\
float textureDayAlpha,\n\
float textureBrightness,\n\
float textureContrast,\n\
float textureHue,\n\
float textureSaturation,\n\
float textureOneOverGamma,\n\
float split,\n\
vec4 colorToAlpha,\n\
float nightBlend)\n\
{\n\
vec2 alphaMultiplier = step(textureCoordinateRectangle.st, tileTextureCoordinates);\n\
textureAlpha = textureAlpha * alphaMultiplier.x * alphaMultiplier.y;\n\
alphaMultiplier = step(vec2(0.0), textureCoordinateRectangle.pq - tileTextureCoordinates);\n\
textureAlpha = textureAlpha * alphaMultiplier.x * alphaMultiplier.y;\n\
#if defined(APPLY_DAY_NIGHT_ALPHA) && defined(ENABLE_DAYNIGHT_SHADING)\n\
textureAlpha *= mix(textureDayAlpha, textureNightAlpha, nightBlend);\n\
#endif\n\
vec2 translation = textureCoordinateTranslationAndScale.xy;\n\
vec2 scale = textureCoordinateTranslationAndScale.zw;\n\
vec2 textureCoordinates = tileTextureCoordinates * scale + translation;\n\
vec4 value = texture2D(textureToSample, textureCoordinates);\n\
vec3 color = value.rgb;\n\
float alpha = value.a;\n\
#ifdef APPLY_COLOR_TO_ALPHA\n\
vec3 colorDiff = abs(color.rgb - colorToAlpha.rgb);\n\
colorDiff.r = max(max(colorDiff.r, colorDiff.g), colorDiff.b);\n\
alpha = czm_branchFreeTernary(colorDiff.r < colorToAlpha.a, 0.0, alpha);\n\
#endif\n\
#if !defined(APPLY_GAMMA)\n\
vec4 tempColor = czm_gammaCorrect(vec4(color, alpha));\n\
color = tempColor.rgb;\n\
alpha = tempColor.a;\n\
#else\n\
color = pow(color, vec3(textureOneOverGamma));\n\
#endif\n\
#ifdef APPLY_SPLIT\n\
float splitPosition = czm_imagerySplitPosition;\n\
if (split < 0.0 && gl_FragCoord.x > splitPosition) {\n\
alpha = 0.0;\n\
}\n\
else if (split > 0.0 && gl_FragCoord.x < splitPosition) {\n\
alpha = 0.0;\n\
}\n\
#endif\n\
#ifdef APPLY_BRIGHTNESS\n\
color = mix(vec3(0.0), color, textureBrightness);\n\
#endif\n\
#ifdef APPLY_CONTRAST\n\
color = mix(vec3(0.5), color, textureContrast);\n\
#endif\n\
#ifdef APPLY_HUE\n\
color = czm_hue(color, textureHue);\n\
#endif\n\
#ifdef APPLY_SATURATION\n\
color = czm_saturation(color, textureSaturation);\n\
#endif\n\
float sourceAlpha = alpha * textureAlpha;\n\
float outAlpha = mix(previousColor.a, 1.0, sourceAlpha);\n\
outAlpha += sign(outAlpha) - 1.0;\n\
vec3 outColor = mix(previousColor.rgb * previousColor.a, color, sourceAlpha) / outAlpha;\n\
return vec4(outColor, max(outAlpha, 0.0));\n\
}\n\
vec3 colorCorrect(vec3 rgb) {\n\
#ifdef COLOR_CORRECT\n\
vec3 hsb = czm_RGBToHSB(rgb);\n\
hsb.x += u_hsbShift.x;\n\
hsb.y = clamp(hsb.y + u_hsbShift.y, 0.0, 1.0);\n\
hsb.z = hsb.z > czm_epsilon7 ? hsb.z + u_hsbShift.z : 0.0;\n\
rgb = czm_HSBToRGB(hsb);\n\
#endif\n\
return rgb;\n\
}\n\
vec4 computeDayColor(vec4 initialColor, vec3 textureCoordinates, float nightBlend);\n\
vec4 computeWaterColor(vec3 positionEyeCoordinates, vec2 textureCoordinates, mat3 enuToEye, vec4 imageryColor, float specularMapValue, float fade);\n\
#ifdef GROUND_ATMOSPHERE\n\
vec3 computeGroundAtmosphereColor(vec3 fogColor, vec4 finalColor, vec3 atmosphereLightDirection, float cameraDist);\n\
#endif\n\
const float fExposure = 2.0;\n\
void main()\n\
{\n\
#ifdef TILE_LIMIT_RECTANGLE\n\
if (v_textureCoordinates.x < u_cartographicLimitRectangle.x || u_cartographicLimitRectangle.z < v_textureCoordinates.x ||\n\
v_textureCoordinates.y < u_cartographicLimitRectangle.y || u_cartographicLimitRectangle.w < v_textureCoordinates.y)\n\
{\n\
discard;\n\
}\n\
#endif\n\
#ifdef ENABLE_CLIPPING_PLANES\n\
float clipDistance = clip(gl_FragCoord, u_clippingPlanes, u_clippingPlanesMatrix);\n\
#endif\n\
#if defined(SHOW_REFLECTIVE_OCEAN) || defined(ENABLE_DAYNIGHT_SHADING) || defined(HDR)\n\
vec3 normalMC = czm_geodeticSurfaceNormal(v_positionMC, vec3(0.0), vec3(1.0));\n\
vec3 normalEC = czm_normal3D * normalMC;\n\
#endif\n\
#if defined(APPLY_DAY_NIGHT_ALPHA) && defined(ENABLE_DAYNIGHT_SHADING)\n\
float nightBlend = 1.0 - clamp(czm_getLambertDiffuse(czm_lightDirectionEC, normalEC) * 5.0, 0.0, 1.0);\n\
#else\n\
float nightBlend = 0.0;\n\
#endif\n\
vec4 color = computeDayColor(u_initialColor, clamp(v_textureCoordinates, 0.0, 1.0), nightBlend);\n\
#ifdef SHOW_TILE_BOUNDARIES\n\
if (v_textureCoordinates.x < (1.0/256.0) || v_textureCoordinates.x > (255.0/256.0) ||\n\
v_textureCoordinates.y < (1.0/256.0) || v_textureCoordinates.y > (255.0/256.0))\n\
{\n\
color = vec4(1.0, 0.0, 0.0, 1.0);\n\
}\n\
#endif\n\
#if defined(ENABLE_DAYNIGHT_SHADING) || defined(GROUND_ATMOSPHERE)\n\
float cameraDist;\n\
if (czm_sceneMode == czm_sceneMode2D)\n\
{\n\
cameraDist = max(czm_frustumPlanes.x - czm_frustumPlanes.y, czm_frustumPlanes.w - czm_frustumPlanes.z) * 0.5;\n\
}\n\
else if (czm_sceneMode == czm_sceneModeColumbusView)\n\
{\n\
cameraDist = -czm_view[3].z;\n\
}\n\
else\n\
{\n\
cameraDist = length(czm_view[3]);\n\
}\n\
float fadeOutDist = u_lightingFadeDistance.x;\n\
float fadeInDist = u_lightingFadeDistance.y;\n\
if (czm_sceneMode != czm_sceneMode3D) {\n\
vec3 radii = czm_ellipsoidRadii;\n\
float maxRadii = max(radii.x, max(radii.y, radii.z));\n\
fadeOutDist -= maxRadii;\n\
fadeInDist -= maxRadii;\n\
}\n\
float fade = clamp((cameraDist - fadeOutDist) / (fadeInDist - fadeOutDist), 0.0, 1.0);\n\
#else\n\
float fade = 0.0;\n\
#endif\n\
#ifdef SHOW_REFLECTIVE_OCEAN\n\
vec2 waterMaskTranslation = u_waterMaskTranslationAndScale.xy;\n\
vec2 waterMaskScale = u_waterMaskTranslationAndScale.zw;\n\
vec2 waterMaskTextureCoordinates = v_textureCoordinates.xy * waterMaskScale + waterMaskTranslation;\n\
waterMaskTextureCoordinates.y = 1.0 - waterMaskTextureCoordinates.y;\n\
float mask = texture2D(u_waterMask, waterMaskTextureCoordinates).r;\n\
if (mask > 0.0)\n\
{\n\
mat3 enuToEye = czm_eastNorthUpToEyeCoordinates(v_positionMC, normalEC);\n\
vec2 ellipsoidTextureCoordinates = czm_ellipsoidWgs84TextureCoordinates(normalMC);\n\
vec2 ellipsoidFlippedTextureCoordinates = czm_ellipsoidWgs84TextureCoordinates(normalMC.zyx);\n\
vec2 textureCoordinates = mix(ellipsoidTextureCoordinates, ellipsoidFlippedTextureCoordinates, czm_morphTime * smoothstep(0.9, 0.95, normalMC.z));\n\
color = computeWaterColor(v_positionEC, textureCoordinates, enuToEye, color, mask, fade);\n\
}\n\
#endif\n\
#ifdef APPLY_MATERIAL\n\
czm_materialInput materialInput;\n\
materialInput.st = v_textureCoordinates.st;\n\
materialInput.normalEC = normalize(v_normalEC);\n\
materialInput.slope = v_slope;\n\
materialInput.height = v_height;\n\
materialInput.aspect = v_aspect;\n\
czm_material material = czm_getMaterial(materialInput);\n\
vec4 materialColor = vec4(material.diffuse, material.alpha);\n\
color = alphaBlend(materialColor, color);\n\
#endif\n\
#ifdef ENABLE_VERTEX_LIGHTING\n\
float diffuseIntensity = clamp(czm_getLambertDiffuse(czm_lightDirectionEC, normalize(v_normalEC)) * 0.9 + 0.3, 0.0, 1.0);\n\
vec4 finalColor = vec4(color.rgb * czm_lightColor * diffuseIntensity, color.a);\n\
#elif defined(ENABLE_DAYNIGHT_SHADING)\n\
float diffuseIntensity = clamp(czm_getLambertDiffuse(czm_lightDirectionEC, normalEC) * 5.0 + 0.3, 0.0, 1.0);\n\
diffuseIntensity = mix(1.0, diffuseIntensity, fade);\n\
vec4 finalColor = vec4(color.rgb * czm_lightColor * diffuseIntensity, color.a);\n\
#else\n\
vec4 finalColor = color;\n\
#endif\n\
#ifdef ENABLE_CLIPPING_PLANES\n\
vec4 clippingPlanesEdgeColor = vec4(1.0);\n\
clippingPlanesEdgeColor.rgb = u_clippingPlanesEdgeStyle.rgb;\n\
float clippingPlanesEdgeWidth = u_clippingPlanesEdgeStyle.a;\n\
if (clipDistance < clippingPlanesEdgeWidth)\n\
{\n\
finalColor = clippingPlanesEdgeColor;\n\
}\n\
#endif\n\
#ifdef HIGHLIGHT_FILL_TILE\n\
finalColor = vec4(mix(finalColor.rgb, u_fillHighlightColor.rgb, u_fillHighlightColor.a), finalColor.a);\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE)\n\
vec3 fogColor = colorCorrect(v_fogMieColor) + finalColor.rgb * colorCorrect(v_fogRayleighColor);\n\
#ifndef HDR\n\
fogColor = vec3(1.0) - exp(-fExposure * fogColor);\n\
#endif\n\
#endif\n\
#if defined(DYNAMIC_ATMOSPHERE_LIGHTING_FROM_SUN)\n\
vec3 atmosphereLightDirection = czm_sunDirectionWC;\n\
#else\n\
vec3 atmosphereLightDirection = czm_lightDirectionWC;\n\
#endif\n\
#ifdef FOG\n\
#if defined(DYNAMIC_ATMOSPHERE_LIGHTING) && (defined(ENABLE_VERTEX_LIGHTING) || defined(ENABLE_DAYNIGHT_SHADING))\n\
float darken = clamp(dot(normalize(czm_viewerPositionWC), atmosphereLightDirection), u_minimumBrightness, 1.0);\n\
fogColor *= darken;\n\
#endif\n\
#ifdef HDR\n\
const float modifier = 0.15;\n\
finalColor = vec4(czm_fog(v_distance, finalColor.rgb, fogColor, modifier), finalColor.a);\n\
#else\n\
finalColor = vec4(czm_fog(v_distance, finalColor.rgb, fogColor), finalColor.a);\n\
#endif\n\
#endif\n\
#ifdef GROUND_ATMOSPHERE\n\
if (!czm_backFacing())\n\
{\n\
vec3 groundAtmosphereColor = computeGroundAtmosphereColor(fogColor, finalColor, atmosphereLightDirection, cameraDist);\n\
finalColor = vec4(mix(finalColor.rgb, groundAtmosphereColor, fade), finalColor.a);\n\
}\n\
#endif\n\
#ifdef UNDERGROUND_COLOR\n\
if (czm_backFacing())\n\
{\n\
float distanceFromEllipsoid = max(czm_eyeHeight, 0.0);\n\
float distance = max(v_distance - distanceFromEllipsoid, 0.0);\n\
float blendAmount = interpolateByDistance(u_undergroundColorAlphaByDistance, distance);\n\
vec4 undergroundColor = vec4(u_undergroundColor.rgb, u_undergroundColor.a * blendAmount);\n\
finalColor = alphaBlend(undergroundColor, finalColor);\n\
}\n\
#endif\n\
#ifdef TRANSLUCENT\n\
if (inTranslucencyRectangle())\n\
{\n\
vec4 alphaByDistance = gl_FrontFacing ? u_frontFaceAlphaByDistance : u_backFaceAlphaByDistance;\n\
finalColor.a *= interpolateByDistance(alphaByDistance, v_distance);\n\
}\n\
#endif\n\
gl_FragColor = finalColor;\n\
}\n\
#ifdef GROUND_ATMOSPHERE\n\
vec3 computeGroundAtmosphereColor(vec3 fogColor, vec4 finalColor, vec3 atmosphereLightDirection, float cameraDist)\n\
{\n\
#if defined(PER_FRAGMENT_GROUND_ATMOSPHERE) && defined(DYNAMIC_ATMOSPHERE_LIGHTING) && (defined(ENABLE_DAYNIGHT_SHADING) || defined(ENABLE_VERTEX_LIGHTING))\n\
float mpp = czm_metersPerPixel(vec4(0.0, 0.0, -czm_currentFrustum.x, 1.0), 1.0);\n\
vec2 xy = gl_FragCoord.xy / czm_viewport.zw * 2.0 - vec2(1.0);\n\
xy *= czm_viewport.zw * mpp * 0.5;\n\
vec3 direction = normalize(vec3(xy, -czm_currentFrustum.x));\n\
czm_ray ray = czm_ray(vec3(0.0), direction);\n\
vec3 ellipsoid_center = czm_view[3].xyz;\n\
czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid_center, czm_ellipsoidInverseRadii);\n\
vec3 ellipsoidPosition = czm_pointAlongRay(ray, intersection.start);\n\
ellipsoidPosition = (czm_inverseView * vec4(ellipsoidPosition, 1.0)).xyz;\n\
AtmosphereColor atmosColor = computeGroundAtmosphereFromSpace(ellipsoidPosition, true, atmosphereLightDirection);\n\
vec3 groundAtmosphereColor = colorCorrect(atmosColor.mie) + finalColor.rgb * colorCorrect(atmosColor.rayleigh);\n\
#ifndef HDR\n\
groundAtmosphereColor = vec3(1.0) - exp(-fExposure * groundAtmosphereColor);\n\
#endif\n\
float fadeInDist = u_nightFadeDistance.x;\n\
float fadeOutDist = u_nightFadeDistance.y;\n\
float sunlitAtmosphereIntensity = clamp((cameraDist - fadeOutDist) / (fadeInDist - fadeOutDist), 0.0, 1.0);\n\
#ifdef HDR\n\
sunlitAtmosphereIntensity = max(sunlitAtmosphereIntensity * sunlitAtmosphereIntensity, 0.03);\n\
#endif\n\
groundAtmosphereColor = mix(groundAtmosphereColor, fogColor, sunlitAtmosphereIntensity);\n\
#else\n\
vec3 groundAtmosphereColor = fogColor;\n\
#endif\n\
#ifdef HDR\n\
groundAtmosphereColor = czm_saturation(groundAtmosphereColor, 1.6);\n\
#endif\n\
return groundAtmosphereColor;\n\
}\n\
#endif\n\
#ifdef SHOW_REFLECTIVE_OCEAN\n\
float waveFade(float edge0, float edge1, float x)\n\
{\n\
float y = clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0);\n\
return pow(1.0 - y, 5.0);\n\
}\n\
float linearFade(float edge0, float edge1, float x)\n\
{\n\
return clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0);\n\
}\n\
const float oceanFrequencyLowAltitude = 825000.0;\n\
const float oceanAnimationSpeedLowAltitude = 0.004;\n\
const float oceanOneOverAmplitudeLowAltitude = 1.0 / 2.0;\n\
const float oceanSpecularIntensity = 0.5;\n\
const float oceanFrequencyHighAltitude = 125000.0;\n\
const float oceanAnimationSpeedHighAltitude = 0.008;\n\
const float oceanOneOverAmplitudeHighAltitude = 1.0 / 2.0;\n\
vec4 computeWaterColor(vec3 positionEyeCoordinates, vec2 textureCoordinates, mat3 enuToEye, vec4 imageryColor, float maskValue, float fade)\n\
{\n\
vec3 positionToEyeEC = -positionEyeCoordinates;\n\
float positionToEyeECLength = length(positionToEyeEC);\n\
vec3 normalizedPositionToEyeEC = normalize(normalize(positionToEyeEC));\n\
float waveIntensity = waveFade(70000.0, 1000000.0, positionToEyeECLength);\n\
#ifdef SHOW_OCEAN_WAVES\n\
float time = czm_frameNumber * oceanAnimationSpeedHighAltitude;\n\
vec4 noise = czm_getWaterNoise(u_oceanNormalMap, textureCoordinates * oceanFrequencyHighAltitude, time, 0.0);\n\
vec3 normalTangentSpaceHighAltitude = vec3(noise.xy, noise.z * oceanOneOverAmplitudeHighAltitude);\n\
time = czm_frameNumber * oceanAnimationSpeedLowAltitude;\n\
noise = czm_getWaterNoise(u_oceanNormalMap, textureCoordinates * oceanFrequencyLowAltitude, time, 0.0);\n\
vec3 normalTangentSpaceLowAltitude = vec3(noise.xy, noise.z * oceanOneOverAmplitudeLowAltitude);\n\
float highAltitudeFade = linearFade(0.0, 60000.0, positionToEyeECLength);\n\
float lowAltitudeFade = 1.0 - linearFade(20000.0, 60000.0, positionToEyeECLength);\n\
vec3 normalTangentSpace =\n\
(highAltitudeFade * normalTangentSpaceHighAltitude) +\n\
(lowAltitudeFade * normalTangentSpaceLowAltitude);\n\
normalTangentSpace = normalize(normalTangentSpace);\n\
normalTangentSpace.xy *= waveIntensity;\n\
normalTangentSpace = normalize(normalTangentSpace);\n\
#else\n\
vec3 normalTangentSpace = vec3(0.0, 0.0, 1.0);\n\
#endif\n\
vec3 normalEC = enuToEye * normalTangentSpace;\n\
const vec3 waveHighlightColor = vec3(0.3, 0.45, 0.6);\n\
float diffuseIntensity = czm_getLambertDiffuse(czm_lightDirectionEC, normalEC) * maskValue;\n\
vec3 diffuseHighlight = waveHighlightColor * diffuseIntensity * (1.0 - fade);\n\
#ifdef SHOW_OCEAN_WAVES\n\
float tsPerturbationRatio = normalTangentSpace.z;\n\
vec3 nonDiffuseHighlight = mix(waveHighlightColor * 5.0 * (1.0 - tsPerturbationRatio), vec3(0.0), diffuseIntensity);\n\
#else\n\
vec3 nonDiffuseHighlight = vec3(0.0);\n\
#endif\n\
float specularIntensity = czm_getSpecular(czm_lightDirectionEC, normalizedPositionToEyeEC, normalEC, 10.0);\n\
float surfaceReflectance = mix(0.0, mix(u_zoomedOutOceanSpecularIntensity, oceanSpecularIntensity, waveIntensity), maskValue);\n\
float specular = specularIntensity * surfaceReflectance;\n\
#ifdef HDR\n\
specular *= 1.4;\n\
float e = 0.2;\n\
float d = 3.3;\n\
float c = 1.7;\n\
vec3 color = imageryColor.rgb + (c * (vec3(e) + imageryColor.rgb * d) * (diffuseHighlight + nonDiffuseHighlight + specular));\n\
#else\n\
vec3 color = imageryColor.rgb + diffuseHighlight + nonDiffuseHighlight + specular;\n\
#endif\n\
return vec4(color, imageryColor.a);\n\
}\n\
#endif // #ifdef SHOW_REFLECTIVE_OCEAN\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var GlobeVS = "#ifdef QUANTIZATION_BITS12\n\
attribute vec4 compressed0;\n\
attribute float compressed1;\n\
#else\n\
attribute vec4 position3DAndHeight;\n\
attribute vec4 textureCoordAndEncodedNormals;\n\
#endif\n\
uniform vec3 u_center3D;\n\
uniform mat4 u_modifiedModelView;\n\
uniform mat4 u_modifiedModelViewProjection;\n\
uniform vec4 u_tileRectangle;\n\
uniform vec2 u_southAndNorthLatitude;\n\
uniform vec2 u_southMercatorYAndOneOverHeight;\n\
varying vec3 v_positionMC;\n\
varying vec3 v_positionEC;\n\
varying vec3 v_textureCoordinates;\n\
varying vec3 v_normalMC;\n\
varying vec3 v_normalEC;\n\
#ifdef APPLY_MATERIAL\n\
varying float v_slope;\n\
varying float v_aspect;\n\
varying float v_height;\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE) || defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT)\n\
varying float v_distance;\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE)\n\
varying vec3 v_fogMieColor;\n\
varying vec3 v_fogRayleighColor;\n\
#endif\n\
vec4 getPosition(vec3 position, float height, vec2 textureCoordinates);\n\
float get2DYPositionFraction(vec2 textureCoordinates);\n\
vec4 getPosition3DMode(vec3 position, float height, vec2 textureCoordinates)\n\
{\n\
return u_modifiedModelViewProjection * vec4(position, 1.0);\n\
}\n\
float get2DMercatorYPositionFraction(vec2 textureCoordinates)\n\
{\n\
const float maxTileWidth = 0.003068;\n\
float positionFraction = textureCoordinates.y;\n\
float southLatitude = u_southAndNorthLatitude.x;\n\
float northLatitude = u_southAndNorthLatitude.y;\n\
if (northLatitude - southLatitude > maxTileWidth)\n\
{\n\
float southMercatorY = u_southMercatorYAndOneOverHeight.x;\n\
float oneOverMercatorHeight = u_southMercatorYAndOneOverHeight.y;\n\
float currentLatitude = mix(southLatitude, northLatitude, textureCoordinates.y);\n\
currentLatitude = clamp(currentLatitude, -czm_webMercatorMaxLatitude, czm_webMercatorMaxLatitude);\n\
positionFraction = czm_latitudeToWebMercatorFraction(currentLatitude, southMercatorY, oneOverMercatorHeight);\n\
}\n\
return positionFraction;\n\
}\n\
float get2DGeographicYPositionFraction(vec2 textureCoordinates)\n\
{\n\
return textureCoordinates.y;\n\
}\n\
vec4 getPositionPlanarEarth(vec3 position, float height, vec2 textureCoordinates)\n\
{\n\
float yPositionFraction = get2DYPositionFraction(textureCoordinates);\n\
vec4 rtcPosition2D = vec4(height, mix(u_tileRectangle.st, u_tileRectangle.pq, vec2(textureCoordinates.x, yPositionFraction)), 1.0);\n\
return u_modifiedModelViewProjection * rtcPosition2D;\n\
}\n\
vec4 getPosition2DMode(vec3 position, float height, vec2 textureCoordinates)\n\
{\n\
return getPositionPlanarEarth(position, 0.0, textureCoordinates);\n\
}\n\
vec4 getPositionColumbusViewMode(vec3 position, float height, vec2 textureCoordinates)\n\
{\n\
return getPositionPlanarEarth(position, height, textureCoordinates);\n\
}\n\
vec4 getPositionMorphingMode(vec3 position, float height, vec2 textureCoordinates)\n\
{\n\
vec3 position3DWC = position + u_center3D;\n\
float yPositionFraction = get2DYPositionFraction(textureCoordinates);\n\
vec4 position2DWC = vec4(height, mix(u_tileRectangle.st, u_tileRectangle.pq, vec2(textureCoordinates.x, yPositionFraction)), 1.0);\n\
vec4 morphPosition = czm_columbusViewMorph(position2DWC, vec4(position3DWC, 1.0), czm_morphTime);\n\
return czm_modelViewProjection * morphPosition;\n\
}\n\
#ifdef QUANTIZATION_BITS12\n\
uniform vec2 u_minMaxHeight;\n\
uniform mat4 u_scaleAndBias;\n\
#endif\n\
void main()\n\
{\n\
#ifdef QUANTIZATION_BITS12\n\
vec2 xy = czm_decompressTextureCoordinates(compressed0.x);\n\
vec2 zh = czm_decompressTextureCoordinates(compressed0.y);\n\
vec3 position = vec3(xy, zh.x);\n\
float height = zh.y;\n\
vec2 textureCoordinates = czm_decompressTextureCoordinates(compressed0.z);\n\
height = height * (u_minMaxHeight.y - u_minMaxHeight.x) + u_minMaxHeight.x;\n\
position = (u_scaleAndBias * vec4(position, 1.0)).xyz;\n\
#if (defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL)) && defined(INCLUDE_WEB_MERCATOR_Y)\n\
float webMercatorT = czm_decompressTextureCoordinates(compressed0.w).x;\n\
float encodedNormal = compressed1;\n\
#elif defined(INCLUDE_WEB_MERCATOR_Y)\n\
float webMercatorT = czm_decompressTextureCoordinates(compressed0.w).x;\n\
float encodedNormal = 0.0;\n\
#elif defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL)\n\
float webMercatorT = textureCoordinates.y;\n\
float encodedNormal = compressed0.w;\n\
#else\n\
float webMercatorT = textureCoordinates.y;\n\
float encodedNormal = 0.0;\n\
#endif\n\
#else\n\
vec3 position = position3DAndHeight.xyz;\n\
float height = position3DAndHeight.w;\n\
vec2 textureCoordinates = textureCoordAndEncodedNormals.xy;\n\
#if (defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL) || defined(APPLY_MATERIAL)) && defined(INCLUDE_WEB_MERCATOR_Y)\n\
float webMercatorT = textureCoordAndEncodedNormals.z;\n\
float encodedNormal = textureCoordAndEncodedNormals.w;\n\
#elif defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL) || defined(APPLY_MATERIAL)\n\
float webMercatorT = textureCoordinates.y;\n\
float encodedNormal = textureCoordAndEncodedNormals.z;\n\
#elif defined(INCLUDE_WEB_MERCATOR_Y)\n\
float webMercatorT = textureCoordAndEncodedNormals.z;\n\
float encodedNormal = 0.0;\n\
#else\n\
float webMercatorT = textureCoordinates.y;\n\
float encodedNormal = 0.0;\n\
#endif\n\
#endif\n\
vec3 position3DWC = position + u_center3D;\n\
gl_Position = getPosition(position, height, textureCoordinates);\n\
v_textureCoordinates = vec3(textureCoordinates, webMercatorT);\n\
#if defined(ENABLE_VERTEX_LIGHTING) || defined(GENERATE_POSITION_AND_NORMAL) || defined(APPLY_MATERIAL)\n\
v_positionEC = (u_modifiedModelView * vec4(position, 1.0)).xyz;\n\
v_positionMC = position3DWC;\n\
vec3 normalMC = czm_octDecode(encodedNormal);\n\
v_normalMC = normalMC;\n\
v_normalEC = czm_normal3D * v_normalMC;\n\
#elif defined(SHOW_REFLECTIVE_OCEAN) || defined(ENABLE_DAYNIGHT_SHADING) || defined(GENERATE_POSITION) || defined(HDR)\n\
v_positionEC = (u_modifiedModelView * vec4(position, 1.0)).xyz;\n\
v_positionMC = position3DWC;\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE)\n\
AtmosphereColor atmosFogColor = computeGroundAtmosphereFromSpace(position3DWC, false, vec3(0.0));\n\
v_fogMieColor = atmosFogColor.mie;\n\
v_fogRayleighColor = atmosFogColor.rayleigh;\n\
#endif\n\
#if defined(FOG) || defined(GROUND_ATMOSPHERE) || defined(UNDERGROUND_COLOR) || defined(TRANSLUCENT)\n\
v_distance = length((czm_modelView3D * vec4(position3DWC, 1.0)).xyz);\n\
#endif\n\
#ifdef APPLY_MATERIAL\n\
float northPoleZ = czm_ellipsoidRadii.z;\n\
vec3 northPolePositionMC = vec3(0.0, 0.0, northPoleZ);\n\
vec3 ellipsoidNormal = normalize(v_positionMC);\n\
vec3 vectorEastMC = normalize(cross(northPolePositionMC - v_positionMC, ellipsoidNormal));\n\
float dotProd = abs(dot(ellipsoidNormal, v_normalMC));\n\
v_slope = acos(dotProd);\n\
vec3 normalRejected = ellipsoidNormal * dotProd;\n\
vec3 normalProjected = v_normalMC - normalRejected;\n\
vec3 aspectVector = normalize(normalProjected);\n\
v_aspect = acos(dot(aspectVector, vectorEastMC));\n\
float determ = dot(cross(vectorEastMC, aspectVector), ellipsoidNormal);\n\
v_aspect = czm_branchFreeTernary(determ < 0.0, 2.0 * czm_pi - v_aspect, v_aspect);\n\
v_height = height;\n\
#endif\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var GroundAtmosphere = "const float Kr = 0.0025;\n\
const float Km = 0.0015;\n\
const float ESun = 15.0;\n\
const float fKrESun = Kr * ESun;\n\
const float fKmESun = Km * ESun;\n\
const float fKr4PI = Kr * 4.0 * czm_pi;\n\
const float fKm4PI = Km * 4.0 * czm_pi;\n\
const vec3 v3InvWavelength = vec3(5.60204474633241, 9.473284437923038, 19.64380261047721);\n\
const float fScaleDepth = 0.25;\n\
struct AtmosphereColor\n\
{\n\
vec3 mie;\n\
vec3 rayleigh;\n\
};\n\
const int nSamples = 2;\n\
const float fSamples = 2.0;\n\
float scale(float fCos)\n\
{\n\
float x = 1.0 - fCos;\n\
return fScaleDepth * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25))));\n\
}\n\
AtmosphereColor computeGroundAtmosphereFromSpace(vec3 v3Pos, bool dynamicLighting, vec3 lightDirectionWC)\n\
{\n\
float fInnerRadius = czm_ellipsoidRadii.x;\n\
float fOuterRadius = czm_ellipsoidRadii.x * 1.025;\n\
float fOuterRadius2 = fOuterRadius * fOuterRadius;\n\
float fScale = 1.0 / (fOuterRadius - fInnerRadius);\n\
float fScaleOverScaleDepth = fScale / fScaleDepth;\n\
vec3 v3Ray = v3Pos - czm_viewerPositionWC;\n\
float fFar = length(v3Ray);\n\
v3Ray /= fFar;\n\
float fCameraHeight = length(czm_viewerPositionWC);\n\
float fCameraHeight2 = fCameraHeight * fCameraHeight;\n\
float B = 2.0 * length(czm_viewerPositionWC) * dot(normalize(czm_viewerPositionWC), v3Ray);\n\
float C = fCameraHeight2 - fOuterRadius2;\n\
float fDet = max(0.0, B*B - 4.0 * C);\n\
float fNear = 0.5 * (-B - sqrt(fDet));\n\
vec3 v3Start = czm_viewerPositionWC + v3Ray * fNear;\n\
fFar -= fNear;\n\
float fDepth = exp((fInnerRadius - fOuterRadius) / fScaleDepth);\n\
float fLightAngle = czm_branchFreeTernary(dynamicLighting, dot(lightDirectionWC, v3Pos) / length(v3Pos), 1.0);\n\
float fCameraAngle = dot(-v3Ray, v3Pos) / length(v3Pos);\n\
float fCameraScale = scale(fCameraAngle);\n\
float fLightScale = scale(fLightAngle);\n\
float fCameraOffset = fDepth*fCameraScale;\n\
float fTemp = (fLightScale + fCameraScale);\n\
float fSampleLength = fFar / fSamples;\n\
float fScaledLength = fSampleLength * fScale;\n\
vec3 v3SampleRay = v3Ray * fSampleLength;\n\
vec3 v3SamplePoint = v3Start + v3SampleRay * 0.5;\n\
vec3 v3FrontColor = vec3(0.0);\n\
vec3 v3Attenuate = vec3(0.0);\n\
for(int i=0; i<nSamples; i++)\n\
{\n\
float fHeight = length(v3SamplePoint);\n\
float fDepth = exp(fScaleOverScaleDepth * (fInnerRadius - fHeight));\n\
float fScatter = fDepth*fTemp - fCameraOffset;\n\
v3Attenuate = exp(-fScatter * (v3InvWavelength * fKr4PI + fKm4PI));\n\
v3FrontColor += v3Attenuate * (fDepth * fScaledLength);\n\
v3SamplePoint += v3SampleRay;\n\
}\n\
AtmosphereColor color;\n\
color.mie = v3FrontColor * (v3InvWavelength * fKrESun + fKmESun);\n\
color.rayleigh = v3Attenuate;\n\
return color;\n\
}\n\
";

  function GlobeSurfaceShader(
    numberOfDayTextures,
    flags,
    material,
    shaderProgram,
    clippingShaderState
  ) {
    this.numberOfDayTextures = numberOfDayTextures;
    this.flags = flags;
    this.material = material;
    this.shaderProgram = shaderProgram;
    this.clippingShaderState = clippingShaderState;
  }

  /**
   * Manages the shaders used to shade the surface of a {@link Globe}.
   *
   * @alias GlobeSurfaceShaderSet
   * @private
   */
  function GlobeSurfaceShaderSet() {
    this.baseVertexShaderSource = undefined;
    this.baseFragmentShaderSource = undefined;

    this._shadersByTexturesFlags = [];

    this.material = undefined;
  }

  function getPositionMode(sceneMode) {
    var getPosition3DMode =
      "vec4 getPosition(vec3 position, float height, vec2 textureCoordinates) { return getPosition3DMode(position, height, textureCoordinates); }";
    var getPositionColumbusViewAnd2DMode =
      "vec4 getPosition(vec3 position, float height, vec2 textureCoordinates) { return getPositionColumbusViewMode(position, height, textureCoordinates); }";
    var getPositionMorphingMode =
      "vec4 getPosition(vec3 position, float height, vec2 textureCoordinates) { return getPositionMorphingMode(position, height, textureCoordinates); }";

    var positionMode;

    switch (sceneMode) {
      case SceneMode$1.SCENE3D:
        positionMode = getPosition3DMode;
        break;
      case SceneMode$1.SCENE2D:
      case SceneMode$1.COLUMBUS_VIEW:
        positionMode = getPositionColumbusViewAnd2DMode;
        break;
      case SceneMode$1.MORPHING:
        positionMode = getPositionMorphingMode;
        break;
    }

    return positionMode;
  }

  function get2DYPositionFraction(useWebMercatorProjection) {
    var get2DYPositionFractionGeographicProjection =
      "float get2DYPositionFraction(vec2 textureCoordinates) { return get2DGeographicYPositionFraction(textureCoordinates); }";
    var get2DYPositionFractionMercatorProjection =
      "float get2DYPositionFraction(vec2 textureCoordinates) { return get2DMercatorYPositionFraction(textureCoordinates); }";
    return useWebMercatorProjection
      ? get2DYPositionFractionMercatorProjection
      : get2DYPositionFractionGeographicProjection;
  }

  GlobeSurfaceShaderSet.prototype.getShaderProgram = function (options) {
    var frameState = options.frameState;
    var surfaceTile = options.surfaceTile;
    var numberOfDayTextures = options.numberOfDayTextures;
    var applyBrightness = options.applyBrightness;
    var applyContrast = options.applyContrast;
    var applyHue = options.applyHue;
    var applySaturation = options.applySaturation;
    var applyGamma = options.applyGamma;
    var applyAlpha = options.applyAlpha;
    var applyDayNightAlpha = options.applyDayNightAlpha;
    var applySplit = options.applySplit;
    var showReflectiveOcean = options.showReflectiveOcean;
    var showOceanWaves = options.showOceanWaves;
    var enableLighting = options.enableLighting;
    var dynamicAtmosphereLighting = options.dynamicAtmosphereLighting;
    var dynamicAtmosphereLightingFromSun =
      options.dynamicAtmosphereLightingFromSun;
    var showGroundAtmosphere = options.showGroundAtmosphere;
    var perFragmentGroundAtmosphere = options.perFragmentGroundAtmosphere;
    var hasVertexNormals = options.hasVertexNormals;
    var useWebMercatorProjection = options.useWebMercatorProjection;
    var enableFog = options.enableFog;
    var enableClippingPlanes = options.enableClippingPlanes;
    var clippingPlanes = options.clippingPlanes;
    var clippedByBoundaries = options.clippedByBoundaries;
    var hasImageryLayerCutout = options.hasImageryLayerCutout;
    var colorCorrect = options.colorCorrect;
    var highlightFillTile = options.highlightFillTile;
    var colorToAlpha = options.colorToAlpha;
    var showUndergroundColor = options.showUndergroundColor;
    var translucent = options.translucent;

    var quantization = 0;
    var quantizationDefine = "";

    var mesh = surfaceTile.renderedMesh;
    var terrainEncoding = mesh.encoding;
    var quantizationMode = terrainEncoding.quantization;
    if (quantizationMode === TerrainQuantization$1.BITS12) {
      quantization = 1;
      quantizationDefine = "QUANTIZATION_BITS12";
    }

    var cartographicLimitRectangleFlag = 0;
    var cartographicLimitRectangleDefine = "";
    if (clippedByBoundaries) {
      cartographicLimitRectangleFlag = 1;
      cartographicLimitRectangleDefine = "TILE_LIMIT_RECTANGLE";
    }

    var imageryCutoutFlag = 0;
    var imageryCutoutDefine = "";
    if (hasImageryLayerCutout) {
      imageryCutoutFlag = 1;
      imageryCutoutDefine = "APPLY_IMAGERY_CUTOUT";
    }

    var sceneMode = frameState.mode;
    var flags =
      sceneMode |
      (applyBrightness << 2) |
      (applyContrast << 3) |
      (applyHue << 4) |
      (applySaturation << 5) |
      (applyGamma << 6) |
      (applyAlpha << 7) |
      (showReflectiveOcean << 8) |
      (showOceanWaves << 9) |
      (enableLighting << 10) |
      (dynamicAtmosphereLighting << 11) |
      (dynamicAtmosphereLightingFromSun << 12) |
      (showGroundAtmosphere << 13) |
      (perFragmentGroundAtmosphere << 14) |
      (hasVertexNormals << 15) |
      (useWebMercatorProjection << 16) |
      (enableFog << 17) |
      (quantization << 18) |
      (applySplit << 19) |
      (enableClippingPlanes << 20) |
      (cartographicLimitRectangleFlag << 21) |
      (imageryCutoutFlag << 22) |
      (colorCorrect << 23) |
      (highlightFillTile << 24) |
      (colorToAlpha << 25) |
      (showUndergroundColor << 26) |
      (translucent << 27) |
      (applyDayNightAlpha << 28);

    var currentClippingShaderState = 0;
    if (defined(clippingPlanes) && clippingPlanes.length > 0) {
      currentClippingShaderState = enableClippingPlanes
        ? clippingPlanes.clippingPlanesState
        : 0;
    }
    var surfaceShader = surfaceTile.surfaceShader;
    if (
      defined(surfaceShader) &&
      surfaceShader.numberOfDayTextures === numberOfDayTextures &&
      surfaceShader.flags === flags &&
      surfaceShader.material === this.material &&
      surfaceShader.clippingShaderState === currentClippingShaderState
    ) {
      return surfaceShader.shaderProgram;
    }

    // New tile, or tile changed number of textures, flags, or clipping planes
    var shadersByFlags = this._shadersByTexturesFlags[numberOfDayTextures];
    if (!defined(shadersByFlags)) {
      shadersByFlags = this._shadersByTexturesFlags[numberOfDayTextures] = [];
    }

    surfaceShader = shadersByFlags[flags];
    if (
      !defined(surfaceShader) ||
      surfaceShader.material !== this.material ||
      surfaceShader.clippingShaderState !== currentClippingShaderState
    ) {
      // Cache miss - we've never seen this combination of numberOfDayTextures and flags before.
      var vs = this.baseVertexShaderSource.clone();
      var fs = this.baseFragmentShaderSource.clone();

      if (currentClippingShaderState !== 0) {
        fs.sources.unshift(
          getClippingFunction(clippingPlanes, frameState.context)
        ); // Need to go before GlobeFS
      }

      vs.defines.push(quantizationDefine);
      fs.defines.push(
        "TEXTURE_UNITS " + numberOfDayTextures,
        cartographicLimitRectangleDefine,
        imageryCutoutDefine
      );

      if (applyBrightness) {
        fs.defines.push("APPLY_BRIGHTNESS");
      }
      if (applyContrast) {
        fs.defines.push("APPLY_CONTRAST");
      }
      if (applyHue) {
        fs.defines.push("APPLY_HUE");
      }
      if (applySaturation) {
        fs.defines.push("APPLY_SATURATION");
      }
      if (applyGamma) {
        fs.defines.push("APPLY_GAMMA");
      }
      if (applyAlpha) {
        fs.defines.push("APPLY_ALPHA");
      }
      if (applyDayNightAlpha) {
        fs.defines.push("APPLY_DAY_NIGHT_ALPHA");
      }
      if (showReflectiveOcean) {
        fs.defines.push("SHOW_REFLECTIVE_OCEAN");
        vs.defines.push("SHOW_REFLECTIVE_OCEAN");
      }
      if (showOceanWaves) {
        fs.defines.push("SHOW_OCEAN_WAVES");
      }
      if (colorToAlpha) {
        fs.defines.push("APPLY_COLOR_TO_ALPHA");
      }
      if (showUndergroundColor) {
        vs.defines.push("UNDERGROUND_COLOR");
        fs.defines.push("UNDERGROUND_COLOR");
      }
      if (translucent) {
        vs.defines.push("TRANSLUCENT");
        fs.defines.push("TRANSLUCENT");
      }
      if (enableLighting) {
        if (hasVertexNormals) {
          vs.defines.push("ENABLE_VERTEX_LIGHTING");
          fs.defines.push("ENABLE_VERTEX_LIGHTING");
        } else {
          vs.defines.push("ENABLE_DAYNIGHT_SHADING");
          fs.defines.push("ENABLE_DAYNIGHT_SHADING");
        }
      }

      if (dynamicAtmosphereLighting) {
        fs.defines.push("DYNAMIC_ATMOSPHERE_LIGHTING");
        if (dynamicAtmosphereLightingFromSun) {
          fs.defines.push("DYNAMIC_ATMOSPHERE_LIGHTING_FROM_SUN");
        }
      }

      if (showGroundAtmosphere) {
        vs.defines.push("GROUND_ATMOSPHERE");
        fs.defines.push("GROUND_ATMOSPHERE");
        if (perFragmentGroundAtmosphere) {
          fs.defines.push("PER_FRAGMENT_GROUND_ATMOSPHERE");
        }
      }

      vs.defines.push("INCLUDE_WEB_MERCATOR_Y");
      fs.defines.push("INCLUDE_WEB_MERCATOR_Y");

      if (enableFog) {
        vs.defines.push("FOG");
        fs.defines.push("FOG");
      }

      if (applySplit) {
        fs.defines.push("APPLY_SPLIT");
      }

      if (enableClippingPlanes) {
        fs.defines.push("ENABLE_CLIPPING_PLANES");
      }

      if (colorCorrect) {
        fs.defines.push("COLOR_CORRECT");
      }

      if (highlightFillTile) {
        fs.defines.push("HIGHLIGHT_FILL_TILE");
      }

      var computeDayColor =
        "\
    vec4 computeDayColor(vec4 initialColor, vec3 textureCoordinates, float nightBlend)\n\
    {\n\
        vec4 color = initialColor;\n";

      if (hasImageryLayerCutout) {
        computeDayColor +=
          "\
        vec4 cutoutAndColorResult;\n\
        bool texelUnclipped;\n";
      }

      for (var i = 0; i < numberOfDayTextures; ++i) {
        if (hasImageryLayerCutout) {
          computeDayColor +=
            "\
        cutoutAndColorResult = u_dayTextureCutoutRectangles[" +
            i +
            "];\n\
        texelUnclipped = v_textureCoordinates.x < cutoutAndColorResult.x || cutoutAndColorResult.z < v_textureCoordinates.x || v_textureCoordinates.y < cutoutAndColorResult.y || cutoutAndColorResult.w < v_textureCoordinates.y;\n\
        cutoutAndColorResult = sampleAndBlend(\n";
        } else {
          computeDayColor += "\
        color = sampleAndBlend(\n";
        }
        computeDayColor +=
          "\
            color,\n\
            u_dayTextures[" +
          i +
          "],\n\
            u_dayTextureUseWebMercatorT[" +
          i +
          "] ? textureCoordinates.xz : textureCoordinates.xy,\n\
            u_dayTextureTexCoordsRectangle[" +
          i +
          "],\n\
            u_dayTextureTranslationAndScale[" +
          i +
          "],\n\
            " +
          (applyAlpha ? "u_dayTextureAlpha[" + i + "]" : "1.0") +
          ",\n\
            " +
          (applyDayNightAlpha ? "u_dayTextureNightAlpha[" + i + "]" : "1.0") +
          ",\n" +
          (applyDayNightAlpha ? "u_dayTextureDayAlpha[" + i + "]" : "1.0") +
          ",\n" +
          (applyBrightness ? "u_dayTextureBrightness[" + i + "]" : "0.0") +
          ",\n\
            " +
          (applyContrast ? "u_dayTextureContrast[" + i + "]" : "0.0") +
          ",\n\
            " +
          (applyHue ? "u_dayTextureHue[" + i + "]" : "0.0") +
          ",\n\
            " +
          (applySaturation ? "u_dayTextureSaturation[" + i + "]" : "0.0") +
          ",\n\
            " +
          (applyGamma ? "u_dayTextureOneOverGamma[" + i + "]" : "0.0") +
          ",\n\
            " +
          (applySplit ? "u_dayTextureSplit[" + i + "]" : "0.0") +
          ",\n\
            " +
          (colorToAlpha ? "u_colorsToAlpha[" + i + "]" : "vec4(0.0)") +
          ",\n\
        nightBlend\
        );\n";
        if (hasImageryLayerCutout) {
          computeDayColor +=
            "\
        color = czm_branchFreeTernary(texelUnclipped, cutoutAndColorResult, color);\n";
        }
      }

      computeDayColor += "\
        return color;\n\
    }";

      fs.sources.push(computeDayColor);

      vs.sources.push(getPositionMode(sceneMode));
      vs.sources.push(get2DYPositionFraction(useWebMercatorProjection));

      var shader = ShaderProgram.fromCache({
        context: frameState.context,
        vertexShaderSource: vs,
        fragmentShaderSource: fs,
        attributeLocations: terrainEncoding.getAttributeLocations(),
      });

      surfaceShader = shadersByFlags[flags] = new GlobeSurfaceShader(
        numberOfDayTextures,
        flags,
        this.material,
        shader,
        currentClippingShaderState
      );
    }

    surfaceTile.surfaceShader = surfaceShader;
    return surfaceShader.shaderProgram;
  };

  GlobeSurfaceShaderSet.prototype.destroy = function () {
    var flags;
    var shader;

    var shadersByTexturesFlags = this._shadersByTexturesFlags;
    for (var textureCount in shadersByTexturesFlags) {
      if (shadersByTexturesFlags.hasOwnProperty(textureCount)) {
        var shadersByFlags = shadersByTexturesFlags[textureCount];
        if (!defined(shadersByFlags)) {
          continue;
        }

        for (flags in shadersByFlags) {
          if (shadersByFlags.hasOwnProperty(flags)) {
            shader = shadersByFlags[flags];
            if (defined(shader)) {
              shader.shaderProgram.destroy();
            }
          }
        }
      }
    }

    return destroyObject(this);
  };

  /**
   * @private
   */
  var ImageryState = {
    UNLOADED: 0,
    TRANSITIONING: 1,
    RECEIVED: 2,
    TEXTURE_LOADED: 3,
    READY: 4,
    FAILED: 5,
    INVALID: 6,
    PLACEHOLDER: 7,
  };
  var ImageryState$1 = Object.freeze(ImageryState);

  /**
   * The state of a {@link QuadtreeTile} in the tile load pipeline.
   * @enum {Number}
   * @private
   */
  var QuadtreeTileLoadState = {
    /**
     * The tile is new and loading has not yet begun.
     * @type QuadtreeTileLoadState
     * @constant
     * @default 0
     */
    START: 0,

    /**
     * Loading is in progress.
     * @type QuadtreeTileLoadState
     * @constant
     * @default 1
     */
    LOADING: 1,

    /**
     * Loading is complete.
     * @type QuadtreeTileLoadState
     * @constant
     * @default 2
     */
    DONE: 2,

    /**
     * The tile has failed to load.
     * @type QuadtreeTileLoadState
     * @constant
     * @default 3
     */
    FAILED: 3,
  };
  var QuadtreeTileLoadState$1 = Object.freeze(QuadtreeTileLoadState);

  /**
   * @private
   */
  var TerrainState$1 = {
    FAILED: 0,
    UNLOADED: 1,
    RECEIVING: 2,
    RECEIVED: 3,
    TRANSFORMING: 4,
    TRANSFORMED: 5,
    READY: 6,
  };
  var TerrainState$2 = Object.freeze(TerrainState$1);

  /**
   * Contains additional information about a {@link QuadtreeTile} of the globe's surface, and
   * encapsulates state transition logic for loading tiles.
   *
   * @constructor
   * @alias GlobeSurfaceTile
   * @private
   */
  function GlobeSurfaceTile() {
    /**
     * The {@link TileImagery} attached to this tile.
     * @type {TileImagery[]}
     * @default []
     */
    this.imagery = [];

    this.waterMaskTexture = undefined;
    this.waterMaskTranslationAndScale = new Cartesian4(0.0, 0.0, 1.0, 1.0);

    this.terrainData = undefined;
    this.vertexArray = undefined;
    this.orientedBoundingBox = undefined;
    this.boundingVolumeSourceTile = undefined;

    /**
     * A bounding region used to estimate distance to the tile. The horizontal bounds are always tight-fitting,
     * but the `minimumHeight` and `maximumHeight` properties may be derived from the min/max of an ancestor tile
     * and be quite loose-fitting and thus very poor for estimating distance. The {@link TileBoundingRegion#boundingVolume}
     * and {@link TileBoundingRegion#boundingSphere} will always be undefined; tiles store these separately.
     * @type {TileBoundingRegion}
     */
    this.tileBoundingRegion = undefined;
    this.occludeePointInScaledSpace = new Cartesian3();

    this.terrainState = TerrainState$2.UNLOADED;
    this.mesh = undefined;
    this.fill = undefined;

    this.pickBoundingSphere = new BoundingSphere();

    this.surfaceShader = undefined;
    this.isClipped = true;

    this.clippedByBoundaries = false;
  }

  Object.defineProperties(GlobeSurfaceTile.prototype, {
    /**
     * Gets a value indicating whether or not this tile is eligible to be unloaded.
     * Typically, a tile is ineligible to be unloaded while an asynchronous operation,
     * such as a request for data, is in progress on it.  A tile will never be
     * unloaded while it is needed for rendering, regardless of the value of this
     * property.
     * @memberof GlobeSurfaceTile.prototype
     * @type {Boolean}
     */
    eligibleForUnloading: {
      get: function () {
        // Do not remove tiles that are transitioning or that have
        // imagery that is transitioning.
        var terrainState = this.terrainState;
        var loadingIsTransitioning =
          terrainState === TerrainState$2.RECEIVING ||
          terrainState === TerrainState$2.TRANSFORMING;

        var shouldRemoveTile = !loadingIsTransitioning;

        var imagery = this.imagery;
        for (var i = 0, len = imagery.length; shouldRemoveTile && i < len; ++i) {
          var tileImagery = imagery[i];
          shouldRemoveTile =
            !defined(tileImagery.loadingImagery) ||
            tileImagery.loadingImagery.state !== ImageryState$1.TRANSITIONING;
        }

        return shouldRemoveTile;
      },
    },

    /**
     * Gets the {@link TerrainMesh} that is used for rendering this tile, if any.
     * Returns the value of the {@link GlobeSurfaceTile#mesh} property if
     * {@link GlobeSurfaceTile#vertexArray} is defined. Otherwise, It returns the
     * {@link TerrainFillMesh#mesh} property of the {@link GlobeSurfaceTile#fill}.
     * If there is no fill, it returns undefined.
     *
     * @memberof GlobeSurfaceTile.prototype
     * @type {TerrainMesh}
     */
    renderedMesh: {
      get: function () {
        if (defined(this.vertexArray)) {
          return this.mesh;
        } else if (defined(this.fill)) {
          return this.fill.mesh;
        }
        return undefined;
      },
    },
  });

  function getPosition$2(encoding, mode, projection, vertices, index, result) {
    encoding.decodePosition(vertices, index, result);

    if (defined(mode) && mode !== SceneMode$1.SCENE3D) {
      var ellipsoid = projection.ellipsoid;
      var positionCart = ellipsoid.cartesianToCartographic(result);
      projection.project(positionCart, result);
      Cartesian3.fromElements(result.z, result.x, result.y, result);
    }

    return result;
  }

  var scratchV0 = new Cartesian3();
  var scratchV1 = new Cartesian3();
  var scratchV2 = new Cartesian3();

  GlobeSurfaceTile.prototype.pick = function (
    ray,
    mode,
    projection,
    cullBackFaces,
    result
  ) {
    var mesh = this.renderedMesh;
    if (!defined(mesh)) {
      return undefined;
    }

    var vertices = mesh.vertices;
    var indices = mesh.indices;
    var encoding = mesh.encoding;
    var indicesLength = indices.length;

    var minT = Number.MAX_VALUE;

    for (var i = 0; i < indicesLength; i += 3) {
      var i0 = indices[i];
      var i1 = indices[i + 1];
      var i2 = indices[i + 2];

      var v0 = getPosition$2(encoding, mode, projection, vertices, i0, scratchV0);
      var v1 = getPosition$2(encoding, mode, projection, vertices, i1, scratchV1);
      var v2 = getPosition$2(encoding, mode, projection, vertices, i2, scratchV2);

      var t = IntersectionTests.rayTriangleParametric(
        ray,
        v0,
        v1,
        v2,
        cullBackFaces
      );
      if (defined(t) && t < minT && t >= 0.0) {
        minT = t;
      }
    }

    return minT !== Number.MAX_VALUE
      ? Ray.getPoint(ray, minT, result)
      : undefined;
  };

  GlobeSurfaceTile.prototype.freeResources = function () {
    if (defined(this.waterMaskTexture)) {
      --this.waterMaskTexture.referenceCount;
      if (this.waterMaskTexture.referenceCount === 0) {
        this.waterMaskTexture.destroy();
      }
      this.waterMaskTexture = undefined;
    }

    this.terrainData = undefined;

    this.terrainState = TerrainState$2.UNLOADED;
    this.mesh = undefined;
    this.fill = this.fill && this.fill.destroy();

    var imageryList = this.imagery;
    for (var i = 0, len = imageryList.length; i < len; ++i) {
      imageryList[i].freeResources();
    }
    this.imagery.length = 0;

    this.freeVertexArray();
  };

  GlobeSurfaceTile.prototype.freeVertexArray = function () {
    GlobeSurfaceTile._freeVertexArray(this.vertexArray);
    this.vertexArray = undefined;
    GlobeSurfaceTile._freeVertexArray(this.wireframeVertexArray);
    this.wireframeVertexArray = undefined;
  };

  GlobeSurfaceTile.initialize = function (
    tile,
    terrainProvider,
    imageryLayerCollection
  ) {
    var surfaceTile = tile.data;
    if (!defined(surfaceTile)) {
      surfaceTile = tile.data = new GlobeSurfaceTile();
    }

    if (tile.state === QuadtreeTileLoadState$1.START) {
      prepareNewTile(tile, terrainProvider, imageryLayerCollection);
      tile.state = QuadtreeTileLoadState$1.LOADING;
    }
  };

  GlobeSurfaceTile.processStateMachine = function (
    tile,
    frameState,
    terrainProvider,
    imageryLayerCollection,
    vertexArraysToDestroy,
    terrainOnly
  ) {
    GlobeSurfaceTile.initialize(tile, terrainProvider, imageryLayerCollection);

    var surfaceTile = tile.data;

    if (tile.state === QuadtreeTileLoadState$1.LOADING) {
      processTerrainStateMachine(
        tile,
        frameState,
        terrainProvider,
        imageryLayerCollection,
        vertexArraysToDestroy
      );
    }

    // From here down we're loading imagery, not terrain. We don't want to load imagery until
    // we're certain that the terrain tiles are actually visible, though. We'll load terrainOnly
    // in these scenarios:
    //   * our bounding volume isn't accurate so we're not certain this tile is really visible (see GlobeSurfaceTileProvider#loadTile).
    //   * we want to upsample from this tile but don't plan to render it (see processTerrainStateMachine).
    if (terrainOnly) {
      return;
    }

    var wasAlreadyRenderable = tile.renderable;

    // The terrain is renderable as soon as we have a valid vertex array.
    tile.renderable = defined(surfaceTile.vertexArray);

    // But it's not done loading until it's in the READY state.
    var isTerrainDoneLoading = surfaceTile.terrainState === TerrainState$2.READY;

    // If this tile's terrain and imagery are just upsampled from its parent, mark the tile as
    // upsampled only.  We won't refine a tile if its four children are upsampled only.
    tile.upsampledFromParent =
      defined(surfaceTile.terrainData) &&
      surfaceTile.terrainData.wasCreatedByUpsampling();

    var isImageryDoneLoading = surfaceTile.processImagery(
      tile,
      terrainProvider,
      frameState
    );

    if (isTerrainDoneLoading && isImageryDoneLoading) {
      var callbacks = tile._loadedCallbacks;
      var newCallbacks = {};
      for (var layerId in callbacks) {
        if (callbacks.hasOwnProperty(layerId)) {
          if (!callbacks[layerId](tile)) {
            newCallbacks[layerId] = callbacks[layerId];
          }
        }
      }
      tile._loadedCallbacks = newCallbacks;

      tile.state = QuadtreeTileLoadState$1.DONE;
    }

    // Once a tile is renderable, it stays renderable, because doing otherwise would
    // cause detail (or maybe even the entire globe) to vanish when adding a new
    // imagery layer. `GlobeSurfaceTileProvider._onLayerAdded` sets renderable to
    // false for all affected tiles that are not currently being rendered.
    if (wasAlreadyRenderable) {
      tile.renderable = true;
    }
  };

  GlobeSurfaceTile.prototype.processImagery = function (
    tile,
    terrainProvider,
    frameState,
    skipLoading
  ) {
    var surfaceTile = tile.data;
    var isUpsampledOnly = tile.upsampledFromParent;
    var isAnyTileLoaded = false;
    var isDoneLoading = true;

    // Transition imagery states
    var tileImageryCollection = surfaceTile.imagery;
    var i, len;
    for (i = 0, len = tileImageryCollection.length; i < len; ++i) {
      var tileImagery = tileImageryCollection[i];
      if (!defined(tileImagery.loadingImagery)) {
        isUpsampledOnly = false;
        continue;
      }

      if (tileImagery.loadingImagery.state === ImageryState$1.PLACEHOLDER) {
        var imageryLayer = tileImagery.loadingImagery.imageryLayer;
        if (imageryLayer.imageryProvider.ready) {
          // Remove the placeholder and add the actual skeletons (if any)
          // at the same position.  Then continue the loop at the same index.
          tileImagery.freeResources();
          tileImageryCollection.splice(i, 1);
          imageryLayer._createTileImagerySkeletons(tile, terrainProvider, i);
          --i;
          len = tileImageryCollection.length;
          continue;
        } else {
          isUpsampledOnly = false;
        }
      }

      var thisTileDoneLoading = tileImagery.processStateMachine(
        tile,
        frameState,
        skipLoading
      );
      isDoneLoading = isDoneLoading && thisTileDoneLoading;

      // The imagery is renderable as soon as we have any renderable imagery for this region.
      isAnyTileLoaded =
        isAnyTileLoaded ||
        thisTileDoneLoading ||
        defined(tileImagery.readyImagery);

      isUpsampledOnly =
        isUpsampledOnly &&
        defined(tileImagery.loadingImagery) &&
        (tileImagery.loadingImagery.state === ImageryState$1.FAILED ||
          tileImagery.loadingImagery.state === ImageryState$1.INVALID);
    }

    tile.upsampledFromParent = isUpsampledOnly;

    // Allow rendering if any available layers are loaded
    tile.renderable = tile.renderable && (isAnyTileLoaded || isDoneLoading);

    return isDoneLoading;
  };

  function prepareNewTile(tile, terrainProvider, imageryLayerCollection) {
    var available = terrainProvider.getTileDataAvailable(
      tile.x,
      tile.y,
      tile.level
    );

    if (!defined(available) && defined(tile.parent)) {
      // Provider doesn't know if this tile is available. Does the parent tile know?
      var parent = tile.parent;
      var parentSurfaceTile = parent.data;
      if (defined(parentSurfaceTile) && defined(parentSurfaceTile.terrainData)) {
        available = parentSurfaceTile.terrainData.isChildAvailable(
          parent.x,
          parent.y,
          tile.x,
          tile.y
        );
      }
    }

    if (available === false) {
      // This tile is not available, so mark it failed so we start upsampling right away.
      tile.data.terrainState = TerrainState$2.FAILED;
    }

    // Map imagery tiles to this terrain tile
    for (var i = 0, len = imageryLayerCollection.length; i < len; ++i) {
      var layer = imageryLayerCollection.get(i);
      if (layer.show) {
        layer._createTileImagerySkeletons(tile, terrainProvider);
      }
    }
  }

  function processTerrainStateMachine(
    tile,
    frameState,
    terrainProvider,
    imageryLayerCollection,
    vertexArraysToDestroy
  ) {
    var surfaceTile = tile.data;

    // If this tile is FAILED, we'll need to upsample from the parent. If the parent isn't
    // ready for that, let's push it along.
    var parent = tile.parent;
    if (
      surfaceTile.terrainState === TerrainState$2.FAILED &&
      parent !== undefined
    ) {
      var parentReady =
        parent.data !== undefined &&
        parent.data.terrainData !== undefined &&
        parent.data.terrainData.canUpsample !== false;
      if (!parentReady) {
        GlobeSurfaceTile.processStateMachine(
          parent,
          frameState,
          terrainProvider,
          imageryLayerCollection,
          true
        );
      }
    }

    if (surfaceTile.terrainState === TerrainState$2.FAILED) {
      upsample(
        surfaceTile,
        tile,
        frameState,
        terrainProvider,
        tile.x,
        tile.y,
        tile.level
      );
    }

    if (surfaceTile.terrainState === TerrainState$2.UNLOADED) {
      requestTileGeometry$1(
        surfaceTile,
        terrainProvider,
        tile.x,
        tile.y,
        tile.level
      );
    }

    if (surfaceTile.terrainState === TerrainState$2.RECEIVED) {
      transform$1(
        surfaceTile,
        frameState,
        terrainProvider,
        tile.x,
        tile.y,
        tile.level
      );
    }

    if (surfaceTile.terrainState === TerrainState$2.TRANSFORMED) {
      createResources$4(
        surfaceTile,
        frameState.context,
        terrainProvider,
        tile.x,
        tile.y,
        tile.level,
        vertexArraysToDestroy
      );
    }

    if (
      surfaceTile.terrainState >= TerrainState$2.RECEIVED &&
      surfaceTile.waterMaskTexture === undefined &&
      terrainProvider.hasWaterMask
    ) {
      var terrainData = surfaceTile.terrainData;
      if (terrainData.waterMask !== undefined) {
        createWaterMaskTextureIfNeeded(frameState.context, surfaceTile);
      } else {
        var sourceTile = surfaceTile._findAncestorTileWithTerrainData(tile);
        if (defined(sourceTile) && defined(sourceTile.data.waterMaskTexture)) {
          surfaceTile.waterMaskTexture = sourceTile.data.waterMaskTexture;
          ++surfaceTile.waterMaskTexture.referenceCount;
          surfaceTile._computeWaterMaskTranslationAndScale(
            tile,
            sourceTile,
            surfaceTile.waterMaskTranslationAndScale
          );
        }
      }
    }
  }

  function upsample(surfaceTile, tile, frameState, terrainProvider, x, y, level) {
    var parent = tile.parent;
    if (!parent) {
      // Trying to upsample from a root tile. No can do. This tile is a failure.
      tile.state = QuadtreeTileLoadState$1.FAILED;
      return;
    }

    var sourceData = parent.data.terrainData;
    var sourceX = parent.x;
    var sourceY = parent.y;
    var sourceLevel = parent.level;

    if (!defined(sourceData)) {
      // Parent is not available, so we can't upsample this tile yet.
      return;
    }

    var terrainDataPromise = sourceData.upsample(
      terrainProvider.tilingScheme,
      sourceX,
      sourceY,
      sourceLevel,
      x,
      y,
      level
    );
    if (!defined(terrainDataPromise)) {
      // The upsample request has been deferred - try again later.
      return;
    }

    surfaceTile.terrainState = TerrainState$2.RECEIVING;

    when(
      terrainDataPromise,
      function (terrainData) {
        surfaceTile.terrainData = terrainData;
        surfaceTile.terrainState = TerrainState$2.RECEIVED;
      },
      function () {
        surfaceTile.terrainState = TerrainState$2.FAILED;
      }
    );
  }

  function requestTileGeometry$1(surfaceTile, terrainProvider, x, y, level) {
    function success(terrainData) {
      surfaceTile.terrainData = terrainData;
      surfaceTile.terrainState = TerrainState$2.RECEIVED;
      surfaceTile.request = undefined;
    }

    function failure() {
      if (surfaceTile.request.state === RequestState$1.CANCELLED) {
        // Cancelled due to low priority - try again later.
        surfaceTile.terrainData = undefined;
        surfaceTile.terrainState = TerrainState$2.UNLOADED;
        surfaceTile.request = undefined;
        return;
      }

      // Initially assume failure.  handleError may retry, in which case the state will
      // change to RECEIVING or UNLOADED.
      surfaceTile.terrainState = TerrainState$2.FAILED;
      surfaceTile.request = undefined;

      var message =
        "Failed to obtain terrain tile X: " +
        x +
        " Y: " +
        y +
        " Level: " +
        level +
        ".";
      terrainProvider._requestError = TileProviderError.handleError(
        terrainProvider._requestError,
        terrainProvider,
        terrainProvider.errorEvent,
        message,
        x,
        y,
        level,
        doRequest
      );
    }

    function doRequest() {
      // Request the terrain from the terrain provider.
      var request = new Request({
        throttle: false,
        throttleByServer: true,
        type: RequestType$1.TERRAIN,
      });
      surfaceTile.request = request;
      var requestPromise = terrainProvider.requestTileGeometry(
        x,
        y,
        level,
        request
      );

      // If the request method returns undefined (instead of a promise), the request
      // has been deferred.
      if (defined(requestPromise)) {
        surfaceTile.terrainState = TerrainState$2.RECEIVING;
        when(requestPromise, success, failure);
      } else {
        // Deferred - try again later.
        surfaceTile.terrainState = TerrainState$2.UNLOADED;
        surfaceTile.request = undefined;
      }
    }

    doRequest();
  }

  function transform$1(surfaceTile, frameState, terrainProvider, x, y, level) {
    var tilingScheme = terrainProvider.tilingScheme;

    var terrainData = surfaceTile.terrainData;
    var meshPromise = terrainData.createMesh(
      tilingScheme,
      x,
      y,
      level,
      frameState.terrainExaggeration
    );

    if (!defined(meshPromise)) {
      // Postponed.
      return;
    }

    surfaceTile.terrainState = TerrainState$2.TRANSFORMING;

    when(
      meshPromise,
      function (mesh) {
        surfaceTile.mesh = mesh;
        surfaceTile.orientedBoundingBox = OrientedBoundingBox.clone(
          mesh.orientedBoundingBox,
          surfaceTile.orientedBoundingBox
        );
        surfaceTile.occludeePointInScaledSpace = Cartesian3.clone(
          mesh.occludeePointInScaledSpace,
          surfaceTile.occludeePointInScaledSpace
        );
        surfaceTile.terrainState = TerrainState$2.TRANSFORMED;
      },
      function () {
        surfaceTile.terrainState = TerrainState$2.FAILED;
      }
    );
  }

  GlobeSurfaceTile._createVertexArrayForMesh = function (context, mesh) {
    var typedArray = mesh.vertices;
    var buffer = Buffer$1.createVertexBuffer({
      context: context,
      typedArray: typedArray,
      usage: BufferUsage$1.STATIC_DRAW,
    });
    var attributes = mesh.encoding.getAttributes(buffer);

    var indexBuffers = mesh.indices.indexBuffers || {};
    var indexBuffer = indexBuffers[context.id];
    if (!defined(indexBuffer) || indexBuffer.isDestroyed()) {
      var indices = mesh.indices;
      indexBuffer = Buffer$1.createIndexBuffer({
        context: context,
        typedArray: indices,
        usage: BufferUsage$1.STATIC_DRAW,
        indexDatatype: IndexDatatype$1.fromSizeInBytes(indices.BYTES_PER_ELEMENT),
      });
      indexBuffer.vertexArrayDestroyable = false;
      indexBuffer.referenceCount = 1;
      indexBuffers[context.id] = indexBuffer;
      mesh.indices.indexBuffers = indexBuffers;
    } else {
      ++indexBuffer.referenceCount;
    }

    return new VertexArray({
      context: context,
      attributes: attributes,
      indexBuffer: indexBuffer,
    });
  };

  GlobeSurfaceTile._freeVertexArray = function (vertexArray) {
    if (defined(vertexArray)) {
      var indexBuffer = vertexArray.indexBuffer;

      vertexArray.destroy();

      if (
        defined(indexBuffer) &&
        !indexBuffer.isDestroyed() &&
        defined(indexBuffer.referenceCount)
      ) {
        --indexBuffer.referenceCount;
        if (indexBuffer.referenceCount === 0) {
          indexBuffer.destroy();
        }
      }
    }
  };

  function createResources$4(
    surfaceTile,
    context,
    terrainProvider,
    x,
    y,
    level,
    vertexArraysToDestroy
  ) {
    surfaceTile.vertexArray = GlobeSurfaceTile._createVertexArrayForMesh(
      context,
      surfaceTile.mesh
    );
    surfaceTile.terrainState = TerrainState$2.READY;
    surfaceTile.fill =
      surfaceTile.fill && surfaceTile.fill.destroy(vertexArraysToDestroy);
  }

  function getContextWaterMaskData(context) {
    var data = context.cache.tile_waterMaskData;

    if (!defined(data)) {
      var allWaterTexture = Texture.create({
        context: context,
        pixelFormat: PixelFormat$1.LUMINANCE,
        pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
        source: {
          arrayBufferView: new Uint8Array([255]),
          width: 1,
          height: 1,
        },
      });
      allWaterTexture.referenceCount = 1;

      var sampler = new Sampler({
        wrapS: TextureWrap$1.CLAMP_TO_EDGE,
        wrapT: TextureWrap$1.CLAMP_TO_EDGE,
        minificationFilter: TextureMinificationFilter$1.LINEAR,
        magnificationFilter: TextureMagnificationFilter$1.LINEAR,
      });

      data = {
        allWaterTexture: allWaterTexture,
        sampler: sampler,
        destroy: function () {
          this.allWaterTexture.destroy();
        },
      };

      context.cache.tile_waterMaskData = data;
    }

    return data;
  }

  function createWaterMaskTextureIfNeeded(context, surfaceTile) {
    var waterMask = surfaceTile.terrainData.waterMask;
    var waterMaskData = getContextWaterMaskData(context);
    var texture;

    var waterMaskLength = waterMask.length;
    if (waterMaskLength === 1) {
      // Length 1 means the tile is entirely land or entirely water.
      // A value of 0 indicates entirely land, a value of 1 indicates entirely water.
      if (waterMask[0] !== 0) {
        texture = waterMaskData.allWaterTexture;
      } else {
        // Leave the texture undefined if the tile is entirely land.
        return;
      }
    } else {
      var textureSize = Math.sqrt(waterMaskLength);
      texture = Texture.create({
        context: context,
        pixelFormat: PixelFormat$1.LUMINANCE,
        pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
        source: {
          width: textureSize,
          height: textureSize,
          arrayBufferView: waterMask,
        },
        sampler: waterMaskData.sampler,
        flipY: false,
      });

      texture.referenceCount = 0;
    }

    ++texture.referenceCount;
    surfaceTile.waterMaskTexture = texture;

    Cartesian4.fromElements(
      0.0,
      0.0,
      1.0,
      1.0,
      surfaceTile.waterMaskTranslationAndScale
    );
  }

  GlobeSurfaceTile.prototype._findAncestorTileWithTerrainData = function (tile) {
    var sourceTile = tile.parent;

    while (
      defined(sourceTile) &&
      (!defined(sourceTile.data) ||
        !defined(sourceTile.data.terrainData) ||
        sourceTile.data.terrainData.wasCreatedByUpsampling())
    ) {
      sourceTile = sourceTile.parent;
    }

    return sourceTile;
  };

  GlobeSurfaceTile.prototype._computeWaterMaskTranslationAndScale = function (
    tile,
    sourceTile,
    result
  ) {
    var sourceTileRectangle = sourceTile.rectangle;
    var tileRectangle = tile.rectangle;
    var tileWidth = tileRectangle.width;
    var tileHeight = tileRectangle.height;

    var scaleX = tileWidth / sourceTileRectangle.width;
    var scaleY = tileHeight / sourceTileRectangle.height;
    result.x =
      (scaleX * (tileRectangle.west - sourceTileRectangle.west)) / tileWidth;
    result.y =
      (scaleY * (tileRectangle.south - sourceTileRectangle.south)) / tileHeight;
    result.z = scaleX;
    result.w = scaleY;

    return result;
  };

  //This file is automatically rebuilt by the Cesium build process.
  var ReprojectWebMercatorFS = "uniform sampler2D u_texture;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
gl_FragColor = texture2D(u_texture, v_textureCoordinates);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ReprojectWebMercatorVS = "attribute vec4 position;\n\
attribute float webMercatorT;\n\
uniform vec2 u_textureDimensions;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
v_textureCoordinates = vec2(position.x, webMercatorT);\n\
gl_Position = czm_viewportOrthographic * (position * vec4(u_textureDimensions, 1.0, 1.0));\n\
}\n\
";

  /**
   * Stores details about a tile of imagery.
   *
   * @alias Imagery
   * @private
   */
  function Imagery(imageryLayer, x, y, level, rectangle) {
    this.imageryLayer = imageryLayer;
    this.x = x;
    this.y = y;
    this.level = level;
    this.request = undefined;

    if (level !== 0) {
      var parentX = (x / 2) | 0;
      var parentY = (y / 2) | 0;
      var parentLevel = level - 1;
      this.parent = imageryLayer.getImageryFromCache(
        parentX,
        parentY,
        parentLevel
      );
    }

    this.state = ImageryState$1.UNLOADED;
    this.imageUrl = undefined;
    this.image = undefined;
    this.texture = undefined;
    this.textureWebMercator = undefined;
    this.credits = undefined;
    this.referenceCount = 0;

    if (!defined(rectangle) && imageryLayer.imageryProvider.ready) {
      var tilingScheme = imageryLayer.imageryProvider.tilingScheme;
      rectangle = tilingScheme.tileXYToRectangle(x, y, level);
    }

    this.rectangle = rectangle;
  }
  Imagery.createPlaceholder = function (imageryLayer) {
    var result = new Imagery(imageryLayer, 0, 0, 0);
    result.addReference();
    result.state = ImageryState$1.PLACEHOLDER;
    return result;
  };

  Imagery.prototype.addReference = function () {
    ++this.referenceCount;
  };

  Imagery.prototype.releaseReference = function () {
    --this.referenceCount;

    if (this.referenceCount === 0) {
      this.imageryLayer.removeImageryFromCache(this);

      if (defined(this.parent)) {
        this.parent.releaseReference();
      }

      if (defined(this.image) && defined(this.image.destroy)) {
        this.image.destroy();
      }

      if (defined(this.texture)) {
        this.texture.destroy();
      }

      if (
        defined(this.textureWebMercator) &&
        this.texture !== this.textureWebMercator
      ) {
        this.textureWebMercator.destroy();
      }

      destroyObject(this);

      return 0;
    }

    return this.referenceCount;
  };

  Imagery.prototype.processStateMachine = function (
    frameState,
    needGeographicProjection,
    skipLoading
  ) {
    if (this.state === ImageryState$1.UNLOADED && !skipLoading) {
      this.state = ImageryState$1.TRANSITIONING;
      this.imageryLayer._requestImagery(this);
    }

    if (this.state === ImageryState$1.RECEIVED) {
      this.state = ImageryState$1.TRANSITIONING;
      this.imageryLayer._createTexture(frameState.context, this);
    }

    // If the imagery is already ready, but we need a geographic version and don't have it yet,
    // we still need to do the reprojection step. This can happen if the Web Mercator version
    // is fine initially, but the geographic one is needed later.
    var needsReprojection =
      this.state === ImageryState$1.READY &&
      needGeographicProjection &&
      !this.texture;

    if (this.state === ImageryState$1.TEXTURE_LOADED || needsReprojection) {
      this.state = ImageryState$1.TRANSITIONING;
      this.imageryLayer._reprojectTexture(
        frameState,
        this,
        needGeographicProjection
      );
    }
  };

  /**
   * The direction to display an ImageryLayer relative to the {@link Scene#imagerySplitPosition}.
   *
   * @enum {Number}
   *
   * @see ImageryLayer#splitDirection
   */
  var ImagerySplitDirection = {
    /**
     * Display the ImageryLayer to the left of the {@link Scene#imagerySplitPosition}.
     *
     * @type {Number}
     * @constant
     */
    LEFT: -1.0,

    /**
     *  Always display the ImageryLayer.
     *
     * @type {Number}
     * @constant
     */
    NONE: 0.0,

    /**
     * Display the ImageryLayer to the right of the {@link Scene#imagerySplitPosition}.
     *
     * @type {Number}
     * @constant
     */
    RIGHT: 1.0,
  };
  var ImagerySplitDirection$1 = Object.freeze(ImagerySplitDirection);

  /**
   * The assocation between a terrain tile and an imagery tile.
   *
   * @alias TileImagery
   * @private
   *
   * @param {Imagery} imagery The imagery tile.
   * @param {Cartesian4} textureCoordinateRectangle The texture rectangle of the tile that is covered
   *        by the imagery, where X=west, Y=south, Z=east, W=north.
   * @param {Boolean} useWebMercatorT true to use the Web Mercator texture coordinates for this imagery tile.
   */
  function TileImagery(imagery, textureCoordinateRectangle, useWebMercatorT) {
    this.readyImagery = undefined;
    this.loadingImagery = imagery;
    this.textureCoordinateRectangle = textureCoordinateRectangle;
    this.textureTranslationAndScale = undefined;
    this.useWebMercatorT = useWebMercatorT;
  }

  /**
   * Frees the resources held by this instance.
   */
  TileImagery.prototype.freeResources = function () {
    if (defined(this.readyImagery)) {
      this.readyImagery.releaseReference();
    }

    if (defined(this.loadingImagery)) {
      this.loadingImagery.releaseReference();
    }
  };

  /**
   * Processes the load state machine for this instance.
   *
   * @param {Tile} tile The tile to which this instance belongs.
   * @param {FrameState} frameState The frameState.
   * @param {Boolean} skipLoading True to skip loading, e.g. new requests, creating textures. This function will
   *                  still synchronously process imagery that's already mostly ready to go, e.g. use textures
   *                  already loaded on ancestor tiles.
   * @returns {Boolean} True if this instance is done loading; otherwise, false.
   */
  TileImagery.prototype.processStateMachine = function (
    tile,
    frameState,
    skipLoading
  ) {
    var loadingImagery = this.loadingImagery;
    var imageryLayer = loadingImagery.imageryLayer;

    loadingImagery.processStateMachine(
      frameState,
      !this.useWebMercatorT,
      skipLoading
    );

    if (loadingImagery.state === ImageryState$1.READY) {
      if (defined(this.readyImagery)) {
        this.readyImagery.releaseReference();
      }
      this.readyImagery = this.loadingImagery;
      this.loadingImagery = undefined;
      this.textureTranslationAndScale = imageryLayer._calculateTextureTranslationAndScale(
        tile,
        this
      );
      return true; // done loading
    }

    // Find some ancestor imagery we can use while this imagery is still loading.
    var ancestor = loadingImagery.parent;
    var closestAncestorThatNeedsLoading;
    while (
      defined(ancestor) &&
      (ancestor.state !== ImageryState$1.READY ||
        (!this.useWebMercatorT && !defined(ancestor.texture)))
    ) {
      if (
        ancestor.state !== ImageryState$1.FAILED &&
        ancestor.state !== ImageryState$1.INVALID
      ) {
        // ancestor is still loading
        closestAncestorThatNeedsLoading =
          closestAncestorThatNeedsLoading || ancestor;
      }
      ancestor = ancestor.parent;
    }

    if (this.readyImagery !== ancestor) {
      if (defined(this.readyImagery)) {
        this.readyImagery.releaseReference();
      }

      this.readyImagery = ancestor;

      if (defined(ancestor)) {
        ancestor.addReference();
        this.textureTranslationAndScale = imageryLayer._calculateTextureTranslationAndScale(
          tile,
          this
        );
      }
    }

    if (
      loadingImagery.state === ImageryState$1.FAILED ||
      loadingImagery.state === ImageryState$1.INVALID
    ) {
      // The imagery tile is failed or invalid, so we'd like to use an ancestor instead.
      if (defined(closestAncestorThatNeedsLoading)) {
        // Push the ancestor's load process along a bit.  This is necessary because some ancestor imagery
        // tiles may not be attached directly to a terrain tile.  Such tiles will never load if
        // we don't do it here.
        closestAncestorThatNeedsLoading.processStateMachine(
          frameState,
          !this.useWebMercatorT,
          skipLoading
        );
        return false; // not done loading
      }
      // This imagery tile is failed or invalid, and we have the "best available" substitute.
      return true; // done loading
    }

    return false; // not done loading
  };

  /**
   * An imagery layer that displays tiled image data from a single imagery provider
   * on a {@link Globe}.
   *
   * @alias ImageryLayer
   * @constructor
   *
   * @param {ImageryProvider} imageryProvider The imagery provider to use.
   * @param {Object} [options] Object with the following properties:
   * @param {Rectangle} [options.rectangle=imageryProvider.rectangle] The rectangle of the layer.  This rectangle
   *        can limit the visible portion of the imagery provider.
   * @param {Number|Function} [options.alpha=1.0] The alpha blending value of this layer, from 0.0 to 1.0.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates of the
   *                          imagery tile for which the alpha is required, and it is expected to return
   *                          the alpha value to use for the tile.
   * @param {Number|Function} [options.nightAlpha=1.0] The alpha blending value of this layer on the night side of the globe, from 0.0 to 1.0.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates of the
   *                          imagery tile for which the alpha is required, and it is expected to return
   *                          the alpha value to use for the tile. This only takes effect when <code>enableLighting</code> is <code>true</code>.
   * @param {Number|Function} [options.dayAlpha=1.0] The alpha blending value of this layer on the day side of the globe, from 0.0 to 1.0.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates of the
   *                          imagery tile for which the alpha is required, and it is expected to return
   *                          the alpha value to use for the tile. This only takes effect when <code>enableLighting</code> is <code>true</code>.
   * @param {Number|Function} [options.brightness=1.0] The brightness of this layer.  1.0 uses the unmodified imagery
   *                          color.  Less than 1.0 makes the imagery darker while greater than 1.0 makes it brighter.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates of the
   *                          imagery tile for which the brightness is required, and it is expected to return
   *                          the brightness value to use for the tile.  The function is executed for every
   *                          frame and for every tile, so it must be fast.
   * @param {Number|Function} [options.contrast=1.0] The contrast of this layer.  1.0 uses the unmodified imagery color.
   *                          Less than 1.0 reduces the contrast while greater than 1.0 increases it.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates of the
   *                          imagery tile for which the contrast is required, and it is expected to return
   *                          the contrast value to use for the tile.  The function is executed for every
   *                          frame and for every tile, so it must be fast.
   * @param {Number|Function} [options.hue=0.0] The hue of this layer.  0.0 uses the unmodified imagery color.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates
   *                          of the imagery tile for which the hue is required, and it is expected to return
   *                          the contrast value to use for the tile.  The function is executed for every
   *                          frame and for every tile, so it must be fast.
   * @param {Number|Function} [options.saturation=1.0] The saturation of this layer.  1.0 uses the unmodified imagery color.
   *                          Less than 1.0 reduces the saturation while greater than 1.0 increases it.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates
   *                          of the imagery tile for which the saturation is required, and it is expected to return
   *                          the contrast value to use for the tile.  The function is executed for every
   *                          frame and for every tile, so it must be fast.
   * @param {Number|Function} [options.gamma=1.0] The gamma correction to apply to this layer.  1.0 uses the unmodified imagery color.
   *                          This can either be a simple number or a function with the signature
   *                          <code>function(frameState, layer, x, y, level)</code>.  The function is passed the
   *                          current frame state, this layer, and the x, y, and level coordinates of the
   *                          imagery tile for which the gamma is required, and it is expected to return
   *                          the gamma value to use for the tile.  The function is executed for every
   *                          frame and for every tile, so it must be fast.
   * @param {ImagerySplitDirection|Function} [options.splitDirection=ImagerySplitDirection.NONE] The {@link ImagerySplitDirection} split to apply to this layer.
   * @param {TextureMinificationFilter} [options.minificationFilter=TextureMinificationFilter.LINEAR] The
   *                                    texture minification filter to apply to this layer. Possible values
   *                                    are <code>TextureMinificationFilter.LINEAR</code> and
   *                                    <code>TextureMinificationFilter.NEAREST</code>.
   * @param {TextureMagnificationFilter} [options.magnificationFilter=TextureMagnificationFilter.LINEAR] The
   *                                     texture minification filter to apply to this layer. Possible values
   *                                     are <code>TextureMagnificationFilter.LINEAR</code> and
   *                                     <code>TextureMagnificationFilter.NEAREST</code>.
   * @param {Boolean} [options.show=true] True if the layer is shown; otherwise, false.
   * @param {Number} [options.maximumAnisotropy=maximum supported] The maximum anisotropy level to use
   *        for texture filtering.  If this parameter is not specified, the maximum anisotropy supported
   *        by the WebGL stack will be used.  Larger values make the imagery look better in horizon
   *        views.
   * @param {Number} [options.minimumTerrainLevel] The minimum terrain level-of-detail at which to show this imagery layer,
   *                 or undefined to show it at all levels.  Level zero is the least-detailed level.
   * @param {Number} [options.maximumTerrainLevel] The maximum terrain level-of-detail at which to show this imagery layer,
   *                 or undefined to show it at all levels.  Level zero is the least-detailed level.
   * @param {Rectangle} [options.cutoutRectangle] Cartographic rectangle for cutting out a portion of this ImageryLayer.
   * @param {Color} [options.colorToAlpha] Color to be used as alpha.
   * @param {Number} [options.colorToAlphaThreshold=0.004] Threshold for color-to-alpha.
   */
  function ImageryLayer(imageryProvider, options) {
    this._imageryProvider = imageryProvider;

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The alpha blending value of this layer, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number}
     * @default 1.0
     */
    this.alpha = defaultValue(
      options.alpha,
      defaultValue(imageryProvider.defaultAlpha, 1.0)
    );

    /**
     * The alpha blending value of this layer on the night side of the globe, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque. This only takes effect when {@link Globe#enableLighting} is <code>true</code>.
     *
     * @type {Number}
     * @default 1.0
     */
    this.nightAlpha = defaultValue(
      options.nightAlpha,
      defaultValue(imageryProvider.defaultNightAlpha, 1.0)
    );

    /**
     * The alpha blending value of this layer on the day side of the globe, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque. This only takes effect when {@link Globe#enableLighting} is <code>true</code>.
     *
     * @type {Number}
     * @default 1.0
     */
    this.dayAlpha = defaultValue(
      options.dayAlpha,
      defaultValue(imageryProvider.defaultDayAlpha, 1.0)
    );

    /**
     * The brightness of this layer.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number}
     * @default {@link ImageryLayer.DEFAULT_BRIGHTNESS}
     */
    this.brightness = defaultValue(
      options.brightness,
      defaultValue(
        imageryProvider.defaultBrightness,
        ImageryLayer.DEFAULT_BRIGHTNESS
      )
    );

    /**
     * The contrast of this layer.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number}
     * @default {@link ImageryLayer.DEFAULT_CONTRAST}
     */
    this.contrast = defaultValue(
      options.contrast,
      defaultValue(imageryProvider.defaultContrast, ImageryLayer.DEFAULT_CONTRAST)
    );

    /**
     * The hue of this layer in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number}
     * @default {@link ImageryLayer.DEFAULT_HUE}
     */
    this.hue = defaultValue(
      options.hue,
      defaultValue(imageryProvider.defaultHue, ImageryLayer.DEFAULT_HUE)
    );

    /**
     * The saturation of this layer. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number}
     * @default {@link ImageryLayer.DEFAULT_SATURATION}
     */
    this.saturation = defaultValue(
      options.saturation,
      defaultValue(
        imageryProvider.defaultSaturation,
        ImageryLayer.DEFAULT_SATURATION
      )
    );

    /**
     * The gamma correction to apply to this layer.  1.0 uses the unmodified imagery color.
     *
     * @type {Number}
     * @default {@link ImageryLayer.DEFAULT_GAMMA}
     */
    this.gamma = defaultValue(
      options.gamma,
      defaultValue(imageryProvider.defaultGamma, ImageryLayer.DEFAULT_GAMMA)
    );

    /**
     * The {@link ImagerySplitDirection} to apply to this layer.
     *
     * @type {ImagerySplitDirection}
     * @default {@link ImageryLayer.DEFAULT_SPLIT}
     */
    this.splitDirection = defaultValue(
      options.splitDirection,
      defaultValue(imageryProvider.defaultSplit, ImageryLayer.DEFAULT_SPLIT)
    );

    /**
     * The {@link TextureMinificationFilter} to apply to this layer.
     * Possible values are {@link TextureMinificationFilter.LINEAR} (the default)
     * and {@link TextureMinificationFilter.NEAREST}.
     *
     * To take effect, this property must be set immediately after adding the imagery layer.
     * Once a texture is loaded it won't be possible to change the texture filter used.
     *
     * @type {TextureMinificationFilter}
     * @default {@link ImageryLayer.DEFAULT_MINIFICATION_FILTER}
     */
    this.minificationFilter = defaultValue(
      options.minificationFilter,
      defaultValue(
        imageryProvider.defaultMinificationFilter,
        ImageryLayer.DEFAULT_MINIFICATION_FILTER
      )
    );

    /**
     * The {@link TextureMagnificationFilter} to apply to this layer.
     * Possible values are {@link TextureMagnificationFilter.LINEAR} (the default)
     * and {@link TextureMagnificationFilter.NEAREST}.
     *
     * To take effect, this property must be set immediately after adding the imagery layer.
     * Once a texture is loaded it won't be possible to change the texture filter used.
     *
     * @type {TextureMagnificationFilter}
     * @default {@link ImageryLayer.DEFAULT_MAGNIFICATION_FILTER}
     */
    this.magnificationFilter = defaultValue(
      options.magnificationFilter,
      defaultValue(
        imageryProvider.defaultMagnificationFilter,
        ImageryLayer.DEFAULT_MAGNIFICATION_FILTER
      )
    );

    /**
     * Determines if this layer is shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    this._minimumTerrainLevel = options.minimumTerrainLevel;
    this._maximumTerrainLevel = options.maximumTerrainLevel;

    this._rectangle = defaultValue(options.rectangle, Rectangle.MAX_VALUE);
    this._maximumAnisotropy = options.maximumAnisotropy;

    this._imageryCache = {};

    this._skeletonPlaceholder = new TileImagery(Imagery.createPlaceholder(this));

    // The value of the show property on the last update.
    this._show = true;

    // The index of this layer in the ImageryLayerCollection.
    this._layerIndex = -1;

    // true if this is the base (lowest shown) layer.
    this._isBaseLayer = false;

    this._requestImageError = undefined;

    this._reprojectComputeCommands = [];

    /**
     * Rectangle cutout in this layer of imagery.
     *
     * @type {Rectangle}
     */
    this.cutoutRectangle = options.cutoutRectangle;

    /**
     * Color value that should be set to transparent.
     *
     * @type {Color}
     */
    this.colorToAlpha = options.colorToAlpha;

    /**
     * Normalized (0-1) threshold for color-to-alpha.
     *
     * @type {Number}
     */
    this.colorToAlphaThreshold = defaultValue(
      options.colorToAlphaThreshold,
      ImageryLayer.DEFAULT_APPLY_COLOR_TO_ALPHA_THRESHOLD
    );
  }

  Object.defineProperties(ImageryLayer.prototype, {
    /**
     * Gets the imagery provider for this layer.
     * @memberof ImageryLayer.prototype
     * @type {ImageryProvider}
     * @readonly
     */
    imageryProvider: {
      get: function () {
        return this._imageryProvider;
      },
    },

    /**
     * Gets the rectangle of this layer.  If this rectangle is smaller than the rectangle of the
     * {@link ImageryProvider}, only a portion of the imagery provider is shown.
     * @memberof ImageryLayer.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._rectangle;
      },
    },
  });

  /**
   * This value is used as the default brightness for the imagery layer if one is not provided during construction
   * or by the imagery provider. This value does not modify the brightness of the imagery.
   * @type {Number}
   * @default 1.0
   */
  ImageryLayer.DEFAULT_BRIGHTNESS = 1.0;
  /**
   * This value is used as the default contrast for the imagery layer if one is not provided during construction
   * or by the imagery provider. This value does not modify the contrast of the imagery.
   * @type {Number}
   * @default 1.0
   */
  ImageryLayer.DEFAULT_CONTRAST = 1.0;
  /**
   * This value is used as the default hue for the imagery layer if one is not provided during construction
   * or by the imagery provider. This value does not modify the hue of the imagery.
   * @type {Number}
   * @default 0.0
   */
  ImageryLayer.DEFAULT_HUE = 0.0;
  /**
   * This value is used as the default saturation for the imagery layer if one is not provided during construction
   * or by the imagery provider. This value does not modify the saturation of the imagery.
   * @type {Number}
   * @default 1.0
   */
  ImageryLayer.DEFAULT_SATURATION = 1.0;
  /**
   * This value is used as the default gamma for the imagery layer if one is not provided during construction
   * or by the imagery provider. This value does not modify the gamma of the imagery.
   * @type {Number}
   * @default 1.0
   */
  ImageryLayer.DEFAULT_GAMMA = 1.0;

  /**
   * This value is used as the default split for the imagery layer if one is not provided during construction
   * or by the imagery provider.
   * @type {ImagerySplitDirection}
   * @default ImagerySplitDirection.NONE
   */
  ImageryLayer.DEFAULT_SPLIT = ImagerySplitDirection$1.NONE;

  /**
   * This value is used as the default texture minification filter for the imagery layer if one is not provided
   * during construction or by the imagery provider.
   * @type {TextureMinificationFilter}
   * @default TextureMinificationFilter.LINEAR
   */
  ImageryLayer.DEFAULT_MINIFICATION_FILTER = TextureMinificationFilter$1.LINEAR;

  /**
   * This value is used as the default texture magnification filter for the imagery layer if one is not provided
   * during construction or by the imagery provider.
   * @type {TextureMagnificationFilter}
   * @default TextureMagnificationFilter.LINEAR
   */
  ImageryLayer.DEFAULT_MAGNIFICATION_FILTER = TextureMagnificationFilter$1.LINEAR;

  /**
   * This value is used as the default threshold for color-to-alpha if one is not provided
   * during construction or by the imagery provider.
   * @type {Number}
   * @default 0.004
   */
  ImageryLayer.DEFAULT_APPLY_COLOR_TO_ALPHA_THRESHOLD = 0.004;

  /**
   * Gets a value indicating whether this layer is the base layer in the
   * {@link ImageryLayerCollection}.  The base layer is the one that underlies all
   * others.  It is special in that it is treated as if it has global rectangle, even if
   * it actually does not, by stretching the texels at the edges over the entire
   * globe.
   *
   * @returns {Boolean} true if this is the base layer; otherwise, false.
   */
  ImageryLayer.prototype.isBaseLayer = function () {
    return this._isBaseLayer;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see ImageryLayer#destroy
   */
  ImageryLayer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * imageryLayer = imageryLayer && imageryLayer.destroy();
   *
   * @see ImageryLayer#isDestroyed
   */
  ImageryLayer.prototype.destroy = function () {
    return destroyObject(this);
  };

  var imageryBoundsScratch = new Rectangle();
  var tileImageryBoundsScratch = new Rectangle();
  var clippedRectangleScratch = new Rectangle();
  var terrainRectangleScratch = new Rectangle();

  /**
   * Computes the intersection of this layer's rectangle with the imagery provider's availability rectangle,
   * producing the overall bounds of imagery that can be produced by this layer.
   *
   * @returns {Promise.<Rectangle>} A promise to a rectangle which defines the overall bounds of imagery that can be produced by this layer.
   *
   * @example
   * // Zoom to an imagery layer.
   * imageryLayer.getViewableRectangle().then(function (rectangle) {
   *     return camera.flyTo({
   *         destination: rectangle
   *     });
   * });
   */
  ImageryLayer.prototype.getViewableRectangle = function () {
    var imageryProvider = this._imageryProvider;
    var rectangle = this._rectangle;
    return imageryProvider.readyPromise.then(function () {
      return Rectangle.intersection(imageryProvider.rectangle, rectangle);
    });
  };

  /**
   * Create skeletons for the imagery tiles that partially or completely overlap a given terrain
   * tile.
   *
   * @private
   *
   * @param {Tile} tile The terrain tile.
   * @param {TerrainProvider} terrainProvider The terrain provider associated with the terrain tile.
   * @param {Number} insertionPoint The position to insert new skeletons before in the tile's imagery list.
   * @returns {Boolean} true if this layer overlaps any portion of the terrain tile; otherwise, false.
   */
  ImageryLayer.prototype._createTileImagerySkeletons = function (
    tile,
    terrainProvider,
    insertionPoint
  ) {
    var surfaceTile = tile.data;

    if (
      defined(this._minimumTerrainLevel) &&
      tile.level < this._minimumTerrainLevel
    ) {
      return false;
    }
    if (
      defined(this._maximumTerrainLevel) &&
      tile.level > this._maximumTerrainLevel
    ) {
      return false;
    }

    var imageryProvider = this._imageryProvider;

    if (!defined(insertionPoint)) {
      insertionPoint = surfaceTile.imagery.length;
    }

    if (!imageryProvider.ready) {
      // The imagery provider is not ready, so we can't create skeletons, yet.
      // Instead, add a placeholder so that we'll know to create
      // the skeletons once the provider is ready.
      this._skeletonPlaceholder.loadingImagery.addReference();
      surfaceTile.imagery.splice(insertionPoint, 0, this._skeletonPlaceholder);
      return true;
    }

    // Use Web Mercator for our texture coordinate computations if this imagery layer uses
    // that projection and the terrain tile falls entirely inside the valid bounds of the
    // projection.
    var useWebMercatorT =
      imageryProvider.tilingScheme.projection instanceof WebMercatorProjection &&
      tile.rectangle.north < WebMercatorProjection.MaximumLatitude &&
      tile.rectangle.south > -WebMercatorProjection.MaximumLatitude;

    // Compute the rectangle of the imagery from this imageryProvider that overlaps
    // the geometry tile.  The ImageryProvider and ImageryLayer both have the
    // opportunity to constrain the rectangle.  The imagery TilingScheme's rectangle
    // always fully contains the ImageryProvider's rectangle.
    var imageryBounds = Rectangle.intersection(
      imageryProvider.rectangle,
      this._rectangle,
      imageryBoundsScratch
    );
    var rectangle = Rectangle.intersection(
      tile.rectangle,
      imageryBounds,
      tileImageryBoundsScratch
    );

    if (!defined(rectangle)) {
      // There is no overlap between this terrain tile and this imagery
      // provider.  Unless this is the base layer, no skeletons need to be created.
      // We stretch texels at the edge of the base layer over the entire globe.
      if (!this.isBaseLayer()) {
        return false;
      }

      var baseImageryRectangle = imageryBounds;
      var baseTerrainRectangle = tile.rectangle;
      rectangle = tileImageryBoundsScratch;

      if (baseTerrainRectangle.south >= baseImageryRectangle.north) {
        rectangle.north = rectangle.south = baseImageryRectangle.north;
      } else if (baseTerrainRectangle.north <= baseImageryRectangle.south) {
        rectangle.north = rectangle.south = baseImageryRectangle.south;
      } else {
        rectangle.south = Math.max(
          baseTerrainRectangle.south,
          baseImageryRectangle.south
        );
        rectangle.north = Math.min(
          baseTerrainRectangle.north,
          baseImageryRectangle.north
        );
      }

      if (baseTerrainRectangle.west >= baseImageryRectangle.east) {
        rectangle.west = rectangle.east = baseImageryRectangle.east;
      } else if (baseTerrainRectangle.east <= baseImageryRectangle.west) {
        rectangle.west = rectangle.east = baseImageryRectangle.west;
      } else {
        rectangle.west = Math.max(
          baseTerrainRectangle.west,
          baseImageryRectangle.west
        );
        rectangle.east = Math.min(
          baseTerrainRectangle.east,
          baseImageryRectangle.east
        );
      }
    }

    var latitudeClosestToEquator = 0.0;
    if (rectangle.south > 0.0) {
      latitudeClosestToEquator = rectangle.south;
    } else if (rectangle.north < 0.0) {
      latitudeClosestToEquator = rectangle.north;
    }

    // Compute the required level in the imagery tiling scheme.
    // The errorRatio should really be imagerySSE / terrainSSE rather than this hard-coded value.
    // But first we need configurable imagery SSE and we need the rendering to be able to handle more
    // images attached to a terrain tile than there are available texture units.  So that's for the future.
    var errorRatio = 1.0;
    var targetGeometricError =
      errorRatio * terrainProvider.getLevelMaximumGeometricError(tile.level);
    var imageryLevel = getLevelWithMaximumTexelSpacing(
      this,
      targetGeometricError,
      latitudeClosestToEquator
    );
    imageryLevel = Math.max(0, imageryLevel);
    var maximumLevel = imageryProvider.maximumLevel;
    if (imageryLevel > maximumLevel) {
      imageryLevel = maximumLevel;
    }

    if (defined(imageryProvider.minimumLevel)) {
      var minimumLevel = imageryProvider.minimumLevel;
      if (imageryLevel < minimumLevel) {
        imageryLevel = minimumLevel;
      }
    }

    var imageryTilingScheme = imageryProvider.tilingScheme;
    var northwestTileCoordinates = imageryTilingScheme.positionToTileXY(
      Rectangle.northwest(rectangle),
      imageryLevel
    );
    var southeastTileCoordinates = imageryTilingScheme.positionToTileXY(
      Rectangle.southeast(rectangle),
      imageryLevel
    );

    // If the southeast corner of the rectangle lies very close to the north or west side
    // of the southeast tile, we don't actually need the southernmost or easternmost
    // tiles.
    // Similarly, if the northwest corner of the rectangle lies very close to the south or east side
    // of the northwest tile, we don't actually need the northernmost or westernmost tiles.

    // We define "very close" as being within 1/512 of the width of the tile.
    var veryCloseX = tile.rectangle.width / 512.0;
    var veryCloseY = tile.rectangle.height / 512.0;

    var northwestTileRectangle = imageryTilingScheme.tileXYToRectangle(
      northwestTileCoordinates.x,
      northwestTileCoordinates.y,
      imageryLevel
    );
    if (
      Math.abs(northwestTileRectangle.south - tile.rectangle.north) <
        veryCloseY &&
      northwestTileCoordinates.y < southeastTileCoordinates.y
    ) {
      ++northwestTileCoordinates.y;
    }
    if (
      Math.abs(northwestTileRectangle.east - tile.rectangle.west) < veryCloseX &&
      northwestTileCoordinates.x < southeastTileCoordinates.x
    ) {
      ++northwestTileCoordinates.x;
    }

    var southeastTileRectangle = imageryTilingScheme.tileXYToRectangle(
      southeastTileCoordinates.x,
      southeastTileCoordinates.y,
      imageryLevel
    );
    if (
      Math.abs(southeastTileRectangle.north - tile.rectangle.south) <
        veryCloseY &&
      southeastTileCoordinates.y > northwestTileCoordinates.y
    ) {
      --southeastTileCoordinates.y;
    }
    if (
      Math.abs(southeastTileRectangle.west - tile.rectangle.east) < veryCloseX &&
      southeastTileCoordinates.x > northwestTileCoordinates.x
    ) {
      --southeastTileCoordinates.x;
    }

    // Create TileImagery instances for each imagery tile overlapping this terrain tile.
    // We need to do all texture coordinate computations in the imagery tile's tiling scheme.

    var terrainRectangle = Rectangle.clone(
      tile.rectangle,
      terrainRectangleScratch
    );
    var imageryRectangle = imageryTilingScheme.tileXYToRectangle(
      northwestTileCoordinates.x,
      northwestTileCoordinates.y,
      imageryLevel
    );
    var clippedImageryRectangle = Rectangle.intersection(
      imageryRectangle,
      imageryBounds,
      clippedRectangleScratch
    );

    var imageryTileXYToRectangle;
    if (useWebMercatorT) {
      imageryTilingScheme.rectangleToNativeRectangle(
        terrainRectangle,
        terrainRectangle
      );
      imageryTilingScheme.rectangleToNativeRectangle(
        imageryRectangle,
        imageryRectangle
      );
      imageryTilingScheme.rectangleToNativeRectangle(
        clippedImageryRectangle,
        clippedImageryRectangle
      );
      imageryTilingScheme.rectangleToNativeRectangle(
        imageryBounds,
        imageryBounds
      );
      imageryTileXYToRectangle = imageryTilingScheme.tileXYToNativeRectangle.bind(
        imageryTilingScheme
      );
      veryCloseX = terrainRectangle.width / 512.0;
      veryCloseY = terrainRectangle.height / 512.0;
    } else {
      imageryTileXYToRectangle = imageryTilingScheme.tileXYToRectangle.bind(
        imageryTilingScheme
      );
    }

    var minU;
    var maxU = 0.0;

    var minV = 1.0;
    var maxV;

    // If this is the northern-most or western-most tile in the imagery tiling scheme,
    // it may not start at the northern or western edge of the terrain tile.
    // Calculate where it does start.
    if (
      !this.isBaseLayer() &&
      Math.abs(clippedImageryRectangle.west - terrainRectangle.west) >= veryCloseX
    ) {
      maxU = Math.min(
        1.0,
        (clippedImageryRectangle.west - terrainRectangle.west) /
          terrainRectangle.width
      );
    }

    if (
      !this.isBaseLayer() &&
      Math.abs(clippedImageryRectangle.north - terrainRectangle.north) >=
        veryCloseY
    ) {
      minV = Math.max(
        0.0,
        (clippedImageryRectangle.north - terrainRectangle.south) /
          terrainRectangle.height
      );
    }

    var initialMinV = minV;

    for (
      var i = northwestTileCoordinates.x;
      i <= southeastTileCoordinates.x;
      i++
    ) {
      minU = maxU;

      imageryRectangle = imageryTileXYToRectangle(
        i,
        northwestTileCoordinates.y,
        imageryLevel
      );
      clippedImageryRectangle = Rectangle.simpleIntersection(
        imageryRectangle,
        imageryBounds,
        clippedRectangleScratch
      );

      if (!defined(clippedImageryRectangle)) {
        continue;
      }

      maxU = Math.min(
        1.0,
        (clippedImageryRectangle.east - terrainRectangle.west) /
          terrainRectangle.width
      );

      // If this is the eastern-most imagery tile mapped to this terrain tile,
      // and there are more imagery tiles to the east of this one, the maxU
      // should be 1.0 to make sure rounding errors don't make the last
      // image fall shy of the edge of the terrain tile.
      if (
        i === southeastTileCoordinates.x &&
        (this.isBaseLayer() ||
          Math.abs(clippedImageryRectangle.east - terrainRectangle.east) <
            veryCloseX)
      ) {
        maxU = 1.0;
      }

      minV = initialMinV;

      for (
        var j = northwestTileCoordinates.y;
        j <= southeastTileCoordinates.y;
        j++
      ) {
        maxV = minV;

        imageryRectangle = imageryTileXYToRectangle(i, j, imageryLevel);
        clippedImageryRectangle = Rectangle.simpleIntersection(
          imageryRectangle,
          imageryBounds,
          clippedRectangleScratch
        );

        if (!defined(clippedImageryRectangle)) {
          continue;
        }

        minV = Math.max(
          0.0,
          (clippedImageryRectangle.south - terrainRectangle.south) /
            terrainRectangle.height
        );

        // If this is the southern-most imagery tile mapped to this terrain tile,
        // and there are more imagery tiles to the south of this one, the minV
        // should be 0.0 to make sure rounding errors don't make the last
        // image fall shy of the edge of the terrain tile.
        if (
          j === southeastTileCoordinates.y &&
          (this.isBaseLayer() ||
            Math.abs(clippedImageryRectangle.south - terrainRectangle.south) <
              veryCloseY)
        ) {
          minV = 0.0;
        }

        var texCoordsRectangle = new Cartesian4(minU, minV, maxU, maxV);
        var imagery = this.getImageryFromCache(i, j, imageryLevel);
        surfaceTile.imagery.splice(
          insertionPoint,
          0,
          new TileImagery(imagery, texCoordsRectangle, useWebMercatorT)
        );
        ++insertionPoint;
      }
    }

    return true;
  };

  /**
   * Calculate the translation and scale for a particular {@link TileImagery} attached to a
   * particular terrain tile.
   *
   * @private
   *
   * @param {Tile} tile The terrain tile.
   * @param {TileImagery} tileImagery The imagery tile mapping.
   * @returns {Cartesian4} The translation and scale where X and Y are the translation and Z and W
   *          are the scale.
   */
  ImageryLayer.prototype._calculateTextureTranslationAndScale = function (
    tile,
    tileImagery
  ) {
    var imageryRectangle = tileImagery.readyImagery.rectangle;
    var terrainRectangle = tile.rectangle;

    if (tileImagery.useWebMercatorT) {
      var tilingScheme =
        tileImagery.readyImagery.imageryLayer.imageryProvider.tilingScheme;
      imageryRectangle = tilingScheme.rectangleToNativeRectangle(
        imageryRectangle,
        imageryBoundsScratch
      );
      terrainRectangle = tilingScheme.rectangleToNativeRectangle(
        terrainRectangle,
        terrainRectangleScratch
      );
    }

    var terrainWidth = terrainRectangle.width;
    var terrainHeight = terrainRectangle.height;

    var scaleX = terrainWidth / imageryRectangle.width;
    var scaleY = terrainHeight / imageryRectangle.height;
    return new Cartesian4(
      (scaleX * (terrainRectangle.west - imageryRectangle.west)) / terrainWidth,
      (scaleY * (terrainRectangle.south - imageryRectangle.south)) /
        terrainHeight,
      scaleX,
      scaleY
    );
  };

  /**
   * Request a particular piece of imagery from the imagery provider.  This method handles raising an
   * error event if the request fails, and retrying the request if necessary.
   *
   * @private
   *
   * @param {Imagery} imagery The imagery to request.
   */
  ImageryLayer.prototype._requestImagery = function (imagery) {
    var imageryProvider = this._imageryProvider;

    var that = this;

    function success(image) {
      if (!defined(image)) {
        return failure();
      }

      imagery.image = image;
      imagery.state = ImageryState$1.RECEIVED;
      imagery.request = undefined;

      TileProviderError.handleSuccess(that._requestImageError);
    }

    function failure(e) {
      if (imagery.request.state === RequestState$1.CANCELLED) {
        // Cancelled due to low priority - try again later.
        imagery.state = ImageryState$1.UNLOADED;
        imagery.request = undefined;
        return;
      }

      // Initially assume failure.  handleError may retry, in which case the state will
      // change to TRANSITIONING.
      imagery.state = ImageryState$1.FAILED;
      imagery.request = undefined;

      var message =
        "Failed to obtain image tile X: " +
        imagery.x +
        " Y: " +
        imagery.y +
        " Level: " +
        imagery.level +
        ".";
      that._requestImageError = TileProviderError.handleError(
        that._requestImageError,
        imageryProvider,
        imageryProvider.errorEvent,
        message,
        imagery.x,
        imagery.y,
        imagery.level,
        doRequest,
        e
      );
    }

    function doRequest() {
      var request = new Request({
        throttle: false,
        throttleByServer: true,
        type: RequestType$1.IMAGERY,
      });
      imagery.request = request;
      imagery.state = ImageryState$1.TRANSITIONING;
      var imagePromise = imageryProvider.requestImage(
        imagery.x,
        imagery.y,
        imagery.level,
        request
      );

      if (!defined(imagePromise)) {
        // Too many parallel requests, so postpone loading tile.
        imagery.state = ImageryState$1.UNLOADED;
        imagery.request = undefined;
        return;
      }

      if (defined(imageryProvider.getTileCredits)) {
        imagery.credits = imageryProvider.getTileCredits(
          imagery.x,
          imagery.y,
          imagery.level
        );
      }

      when(imagePromise, success, failure);
    }

    doRequest();
  };

  ImageryLayer.prototype._createTextureWebGL = function (context, imagery) {
    var sampler = new Sampler({
      minificationFilter: this.minificationFilter,
      magnificationFilter: this.magnificationFilter,
    });

    var image = imagery.image;

    if (defined(image.internalFormat)) {
      return new Texture({
        context: context,
        pixelFormat: image.internalFormat,
        width: image.width,
        height: image.height,
        source: {
          arrayBufferView: image.bufferView,
        },
        sampler: sampler,
      });
    }
    return new Texture({
      context: context,
      source: image,
      pixelFormat: this._imageryProvider.hasAlphaChannel
        ? PixelFormat$1.RGBA
        : PixelFormat$1.RGB,
      sampler: sampler,
    });
  };

  /**
   * Create a WebGL texture for a given {@link Imagery} instance.
   *
   * @private
   *
   * @param {Context} context The rendered context to use to create textures.
   * @param {Imagery} imagery The imagery for which to create a texture.
   */
  ImageryLayer.prototype._createTexture = function (context, imagery) {
    var imageryProvider = this._imageryProvider;
    var image = imagery.image;

    // If this imagery provider has a discard policy, use it to check if this
    // image should be discarded.
    if (defined(imageryProvider.tileDiscardPolicy)) {
      var discardPolicy = imageryProvider.tileDiscardPolicy;
      if (defined(discardPolicy)) {
        // If the discard policy is not ready yet, transition back to the
        // RECEIVED state and we'll try again next time.
        if (!discardPolicy.isReady()) {
          imagery.state = ImageryState$1.RECEIVED;
          return;
        }

        // Mark discarded imagery tiles invalid.  Parent imagery will be used instead.
        if (discardPolicy.shouldDiscardImage(image)) {
          imagery.state = ImageryState$1.INVALID;
          return;
        }
      }
    }

    //>>includeStart('debug', pragmas.debug);
    if (
      this.minificationFilter !== TextureMinificationFilter$1.NEAREST &&
      this.minificationFilter !== TextureMinificationFilter$1.LINEAR
    ) {
      throw new DeveloperError(
        "ImageryLayer minification filter must be NEAREST or LINEAR"
      );
    }
    //>>includeEnd('debug');

    // Imagery does not need to be discarded, so upload it to WebGL.
    var texture = this._createTextureWebGL(context, imagery);

    if (
      imageryProvider.tilingScheme.projection instanceof WebMercatorProjection
    ) {
      imagery.textureWebMercator = texture;
    } else {
      imagery.texture = texture;
    }
    imagery.image = undefined;
    imagery.state = ImageryState$1.TEXTURE_LOADED;
  };

  function getSamplerKey(
    minificationFilter,
    magnificationFilter,
    maximumAnisotropy
  ) {
    return (
      minificationFilter + ":" + magnificationFilter + ":" + maximumAnisotropy
    );
  }

  ImageryLayer.prototype._finalizeReprojectTexture = function (context, texture) {
    var minificationFilter = this.minificationFilter;
    var magnificationFilter = this.magnificationFilter;
    var usesLinearTextureFilter =
      minificationFilter === TextureMinificationFilter$1.LINEAR &&
      magnificationFilter === TextureMagnificationFilter$1.LINEAR;
    // Use mipmaps if this texture has power-of-two dimensions.
    // In addition, mipmaps are only generated if the texture filters are both LINEAR.
    if (
      usesLinearTextureFilter &&
      !PixelFormat$1.isCompressedFormat(texture.pixelFormat) &&
      CesiumMath.isPowerOfTwo(texture.width) &&
      CesiumMath.isPowerOfTwo(texture.height)
    ) {
      minificationFilter = TextureMinificationFilter$1.LINEAR_MIPMAP_LINEAR;
      var maximumSupportedAnisotropy =
        ContextLimits.maximumTextureFilterAnisotropy;
      var maximumAnisotropy = Math.min(
        maximumSupportedAnisotropy,
        defaultValue(this._maximumAnisotropy, maximumSupportedAnisotropy)
      );
      var mipmapSamplerKey = getSamplerKey(
        minificationFilter,
        magnificationFilter,
        maximumAnisotropy
      );
      var mipmapSamplers = context.cache.imageryLayerMipmapSamplers;
      if (!defined(mipmapSamplers)) {
        mipmapSamplers = {};
        context.cache.imageryLayerMipmapSamplers = mipmapSamplers;
      }
      var mipmapSampler = mipmapSamplers[mipmapSamplerKey];
      if (!defined(mipmapSampler)) {
        mipmapSampler = mipmapSamplers[mipmapSamplerKey] = new Sampler({
          wrapS: TextureWrap$1.CLAMP_TO_EDGE,
          wrapT: TextureWrap$1.CLAMP_TO_EDGE,
          minificationFilter: minificationFilter,
          magnificationFilter: magnificationFilter,
          maximumAnisotropy: maximumAnisotropy,
        });
      }
      texture.generateMipmap(MipmapHint$1.NICEST);
      texture.sampler = mipmapSampler;
    } else {
      var nonMipmapSamplerKey = getSamplerKey(
        minificationFilter,
        magnificationFilter,
        0
      );
      var nonMipmapSamplers = context.cache.imageryLayerNonMipmapSamplers;
      if (!defined(nonMipmapSamplers)) {
        nonMipmapSamplers = {};
        context.cache.imageryLayerNonMipmapSamplers = nonMipmapSamplers;
      }
      var nonMipmapSampler = nonMipmapSamplers[nonMipmapSamplerKey];
      if (!defined(nonMipmapSampler)) {
        nonMipmapSampler = nonMipmapSamplers[nonMipmapSamplerKey] = new Sampler({
          wrapS: TextureWrap$1.CLAMP_TO_EDGE,
          wrapT: TextureWrap$1.CLAMP_TO_EDGE,
          minificationFilter: minificationFilter,
          magnificationFilter: magnificationFilter,
        });
      }
      texture.sampler = nonMipmapSampler;
    }
  };

  /**
   * Enqueues a command re-projecting a texture to a {@link GeographicProjection} on the next update, if necessary, and generate
   * mipmaps for the geographic texture.
   *
   * @private
   *
   * @param {FrameState} frameState The frameState.
   * @param {Imagery} imagery The imagery instance to reproject.
   * @param {Boolean} [needGeographicProjection=true] True to reproject to geographic, or false if Web Mercator is fine.
   */
  ImageryLayer.prototype._reprojectTexture = function (
    frameState,
    imagery,
    needGeographicProjection
  ) {
    var texture = imagery.textureWebMercator || imagery.texture;
    var rectangle = imagery.rectangle;
    var context = frameState.context;

    needGeographicProjection = defaultValue(needGeographicProjection, true);

    // Reproject this texture if it is not already in a geographic projection and
    // the pixels are more than 1e-5 radians apart.  The pixel spacing cutoff
    // avoids precision problems in the reprojection transformation while making
    // no noticeable difference in the georeferencing of the image.
    if (
      needGeographicProjection &&
      !(
        this._imageryProvider.tilingScheme.projection instanceof
        GeographicProjection
      ) &&
      rectangle.width / texture.width > 1e-5
    ) {
      var that = this;
      imagery.addReference();
      var computeCommand = new ComputeCommand({
        persists: true,
        owner: this,
        // Update render resources right before execution instead of now.
        // This allows different ImageryLayers to share the same vao and buffers.
        preExecute: function (command) {
          reprojectToGeographic(command, context, texture, imagery.rectangle);
        },
        postExecute: function (outputTexture) {
          imagery.texture = outputTexture;
          that._finalizeReprojectTexture(context, outputTexture);
          imagery.state = ImageryState$1.READY;
          imagery.releaseReference();
        },
      });
      this._reprojectComputeCommands.push(computeCommand);
    } else {
      if (needGeographicProjection) {
        imagery.texture = texture;
      }
      this._finalizeReprojectTexture(context, texture);
      imagery.state = ImageryState$1.READY;
    }
  };

  /**
   * Updates frame state to execute any queued texture re-projections.
   *
   * @private
   *
   * @param {FrameState} frameState The frameState.
   */
  ImageryLayer.prototype.queueReprojectionCommands = function (frameState) {
    var computeCommands = this._reprojectComputeCommands;
    var length = computeCommands.length;
    for (var i = 0; i < length; ++i) {
      frameState.commandList.push(computeCommands[i]);
    }
    computeCommands.length = 0;
  };

  /**
   * Cancels re-projection commands queued for the next frame.
   *
   * @private
   */
  ImageryLayer.prototype.cancelReprojections = function () {
    this._reprojectComputeCommands.length = 0;
  };

  ImageryLayer.prototype.getImageryFromCache = function (
    x,
    y,
    level,
    imageryRectangle
  ) {
    var cacheKey = getImageryCacheKey(x, y, level);
    var imagery = this._imageryCache[cacheKey];

    if (!defined(imagery)) {
      imagery = new Imagery(this, x, y, level, imageryRectangle);
      this._imageryCache[cacheKey] = imagery;
    }

    imagery.addReference();
    return imagery;
  };

  ImageryLayer.prototype.removeImageryFromCache = function (imagery) {
    var cacheKey = getImageryCacheKey(imagery.x, imagery.y, imagery.level);
    delete this._imageryCache[cacheKey];
  };

  function getImageryCacheKey(x, y, level) {
    return JSON.stringify([x, y, level]);
  }

  var uniformMap = {
    u_textureDimensions: function () {
      return this.textureDimensions;
    },
    u_texture: function () {
      return this.texture;
    },

    textureDimensions: new Cartesian2(),
    texture: undefined,
  };

  var float32ArrayScratch = FeatureDetection.supportsTypedArrays()
    ? new Float32Array(2 * 64)
    : undefined;

  function reprojectToGeographic(command, context, texture, rectangle) {
    // This function has gone through a number of iterations, because GPUs are awesome.
    //
    // Originally, we had a very simple vertex shader and computed the Web Mercator texture coordinates
    // per-fragment in the fragment shader.  That worked well, except on mobile devices, because
    // fragment shaders have limited precision on many mobile devices.  The result was smearing artifacts
    // at medium zoom levels because different geographic texture coordinates would be reprojected to Web
    // Mercator as the same value.
    //
    // Our solution was to reproject to Web Mercator in the vertex shader instead of the fragment shader.
    // This required far more vertex data.  With fragment shader reprojection, we only needed a single quad.
    // But to achieve the same precision with vertex shader reprojection, we needed a vertex for each
    // output pixel.  So we used a grid of 256x256 vertices, because most of our imagery
    // tiles are 256x256.  Fortunately the grid could be created and uploaded to the GPU just once and
    // re-used for all reprojections, so the performance was virtually unchanged from our original fragment
    // shader approach.  See https://github.com/CesiumGS/cesium/pull/714.
    //
    // Over a year later, we noticed (https://github.com/CesiumGS/cesium/issues/2110)
    // that our reprojection code was creating a rare but severe artifact on some GPUs (Intel HD 4600
    // for one).  The problem was that the GLSL sin function on these GPUs had a discontinuity at fine scales in
    // a few places.
    //
    // We solved this by implementing a more reliable sin function based on the CORDIC algorithm
    // (https://github.com/CesiumGS/cesium/pull/2111).  Even though this was a fair
    // amount of code to be executing per vertex, the performance seemed to be pretty good on most GPUs.
    // Unfortunately, on some GPUs, the performance was absolutely terrible
    // (https://github.com/CesiumGS/cesium/issues/2258).
    //
    // So that brings us to our current solution, the one you see here.  Effectively, we compute the Web
    // Mercator texture coordinates on the CPU and store the T coordinate with each vertex (the S coordinate
    // is the same in Geographic and Web Mercator).  To make this faster, we reduced our reprojection mesh
    // to be only 2 vertices wide and 64 vertices high.  We should have reduced the width to 2 sooner,
    // because the extra vertices weren't buying us anything.  The height of 64 means we are technically
    // doing a slightly less accurate reprojection than we were before, but we can't see the difference
    // so it's worth the 4x speedup.

    var reproject = context.cache.imageryLayer_reproject;

    if (!defined(reproject)) {
      reproject = context.cache.imageryLayer_reproject = {
        vertexArray: undefined,
        shaderProgram: undefined,
        sampler: undefined,
        destroy: function () {
          if (defined(this.framebuffer)) {
            this.framebuffer.destroy();
          }
          if (defined(this.vertexArray)) {
            this.vertexArray.destroy();
          }
          if (defined(this.shaderProgram)) {
            this.shaderProgram.destroy();
          }
        },
      };

      var positions = new Float32Array(2 * 64 * 2);
      var index = 0;
      for (var j = 0; j < 64; ++j) {
        var y = j / 63.0;
        positions[index++] = 0.0;
        positions[index++] = y;
        positions[index++] = 1.0;
        positions[index++] = y;
      }

      var reprojectAttributeIndices = {
        position: 0,
        webMercatorT: 1,
      };

      var indices = TerrainProvider.getRegularGridIndices(2, 64);
      var indexBuffer = Buffer$1.createIndexBuffer({
        context: context,
        typedArray: indices,
        usage: BufferUsage$1.STATIC_DRAW,
        indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
      });

      reproject.vertexArray = new VertexArray({
        context: context,
        attributes: [
          {
            index: reprojectAttributeIndices.position,
            vertexBuffer: Buffer$1.createVertexBuffer({
              context: context,
              typedArray: positions,
              usage: BufferUsage$1.STATIC_DRAW,
            }),
            componentsPerAttribute: 2,
          },
          {
            index: reprojectAttributeIndices.webMercatorT,
            vertexBuffer: Buffer$1.createVertexBuffer({
              context: context,
              sizeInBytes: 64 * 2 * 4,
              usage: BufferUsage$1.STREAM_DRAW,
            }),
            componentsPerAttribute: 1,
          },
        ],
        indexBuffer: indexBuffer,
      });

      var vs = new ShaderSource({
        sources: [ReprojectWebMercatorVS],
      });

      reproject.shaderProgram = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: vs,
        fragmentShaderSource: ReprojectWebMercatorFS,
        attributeLocations: reprojectAttributeIndices,
      });

      reproject.sampler = new Sampler({
        wrapS: TextureWrap$1.CLAMP_TO_EDGE,
        wrapT: TextureWrap$1.CLAMP_TO_EDGE,
        minificationFilter: TextureMinificationFilter$1.LINEAR,
        magnificationFilter: TextureMagnificationFilter$1.LINEAR,
      });
    }

    texture.sampler = reproject.sampler;

    var width = texture.width;
    var height = texture.height;

    uniformMap.textureDimensions.x = width;
    uniformMap.textureDimensions.y = height;
    uniformMap.texture = texture;

    var sinLatitude = Math.sin(rectangle.south);
    var southMercatorY = 0.5 * Math.log((1 + sinLatitude) / (1 - sinLatitude));

    sinLatitude = Math.sin(rectangle.north);
    var northMercatorY = 0.5 * Math.log((1 + sinLatitude) / (1 - sinLatitude));
    var oneOverMercatorHeight = 1.0 / (northMercatorY - southMercatorY);

    var outputTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: texture.pixelFormat,
      pixelDatatype: texture.pixelDatatype,
      preMultiplyAlpha: texture.preMultiplyAlpha,
    });

    // Allocate memory for the mipmaps.  Failure to do this before rendering
    // to the texture via the FBO, and calling generateMipmap later,
    // will result in the texture appearing blank.  I can't pretend to
    // understand exactly why this is.
    if (CesiumMath.isPowerOfTwo(width) && CesiumMath.isPowerOfTwo(height)) {
      outputTexture.generateMipmap(MipmapHint$1.NICEST);
    }

    var south = rectangle.south;
    var north = rectangle.north;

    var webMercatorT = float32ArrayScratch;

    var outputIndex = 0;
    for (var webMercatorTIndex = 0; webMercatorTIndex < 64; ++webMercatorTIndex) {
      var fraction = webMercatorTIndex / 63.0;
      var latitude = CesiumMath.lerp(south, north, fraction);
      sinLatitude = Math.sin(latitude);
      var mercatorY = 0.5 * Math.log((1.0 + sinLatitude) / (1.0 - sinLatitude));
      var mercatorFraction = (mercatorY - southMercatorY) * oneOverMercatorHeight;
      webMercatorT[outputIndex++] = mercatorFraction;
      webMercatorT[outputIndex++] = mercatorFraction;
    }

    reproject.vertexArray
      .getAttribute(1)
      .vertexBuffer.copyFromArrayView(webMercatorT);

    command.shaderProgram = reproject.shaderProgram;
    command.outputTexture = outputTexture;
    command.uniformMap = uniformMap;
    command.vertexArray = reproject.vertexArray;
  }

  /**
   * Gets the level with the specified world coordinate spacing between texels, or less.
   *
   * @param {ImageryLayer} layer The imagery layer to use.
   * @param {Number} texelSpacing The texel spacing for which to find a corresponding level.
   * @param {Number} latitudeClosestToEquator The latitude closest to the equator that we're concerned with.
   * @returns {Number} The level with the specified texel spacing or less.
   * @private
   */
  function getLevelWithMaximumTexelSpacing(
    layer,
    texelSpacing,
    latitudeClosestToEquator
  ) {
    // PERFORMANCE_IDEA: factor out the stuff that doesn't change.
    var imageryProvider = layer._imageryProvider;
    var tilingScheme = imageryProvider.tilingScheme;
    var ellipsoid = tilingScheme.ellipsoid;
    var latitudeFactor = !(
      layer._imageryProvider.tilingScheme.projection instanceof
      GeographicProjection
    )
      ? Math.cos(latitudeClosestToEquator)
      : 1.0;
    var tilingSchemeRectangle = tilingScheme.rectangle;
    var levelZeroMaximumTexelSpacing =
      (ellipsoid.maximumRadius * tilingSchemeRectangle.width * latitudeFactor) /
      (imageryProvider.tileWidth * tilingScheme.getNumberOfXTilesAtLevel(0));

    var twoToTheLevelPower = levelZeroMaximumTexelSpacing / texelSpacing;
    var level = Math.log(twoToTheLevelPower) / Math.log(2);
    var rounded = Math.round(level);
    return rounded | 0;
  }

  /**
   * Indicates what happened the last time this tile was visited for selection.
   * @private
   */
  var TileSelectionResult = {
    /**
     * There was no selection result, perhaps because the tile wasn't visited
     * last frame.
     */
    NONE: 0,

    /**
     * This tile was deemed not visible and culled.
     */
    CULLED: 1,

    /**
     * The tile was selected for rendering.
     */
    RENDERED: 2,

    /**
     * This tile did not meet the required screen-space error and was refined.
     */
    REFINED: 3,

    /**
     * This tile was originally rendered, but it got kicked out of the render list
     * in favor of an ancestor because it is not yet renderable.
     */
    RENDERED_AND_KICKED: 2 | 4,

    /**
     * This tile was originally refined, but its rendered descendants got kicked out of the
     * render list in favor of an ancestor because it is not yet renderable.
     */
    REFINED_AND_KICKED: 3 | 4,

    /**
     * This tile was culled because it was not visible, but it still needs to be loaded
     * and any heights on it need to be updated because the camera's position or the
     * camera's reference frame's origin falls inside this tile. Loading this tile
     * could affect the position of the camera if the camera is currently below
     * terrain or if it is tracking an object whose height is referenced to terrain.
     * And a change in the camera position may, in turn, affect what is culled.
     */
    CULLED_BUT_NEEDED: 1 | 8,

    /**
     * Determines if a selection result indicates that this tile or its descendants were
     * kicked from the render list. In other words, if it is <code>RENDERED_AND_KICKED</code>
     * or <code>REFINED_AND_KICKED</code>.
     *
     * @param {TileSelectionResult} value The selection result to test.
     * @returns {Boolean} true if the tile was kicked, no matter if it was originally rendered or refined.
     */
    wasKicked: function (value) {
      return value >= TileSelectionResult.RENDERED_AND_KICKED;
    },

    /**
     * Determines the original selection result prior to being kicked or CULLED_BUT_NEEDED.
     * If the tile wasn't kicked or CULLED_BUT_NEEDED, the original value is returned.
     * @param {TileSelectionResult} value The selection result.
     * @returns {TileSelectionResult} The original selection result prior to kicking.
     */
    originalResult: function (value) {
      return value & 3;
    },

    /**
     * Converts this selection result to a kick.
     * @param {TileSelectionResult} value The original selection result.
     * @returns {TileSelectionResult} The kicked form of the selection result.
     */
    kick: function (value) {
      return value | 4;
    },
  };

  function TerrainFillMesh(tile) {
    this.tile = tile;
    this.frameLastUpdated = undefined;
    this.westMeshes = []; // north to south (CCW)
    this.westTiles = [];
    this.southMeshes = []; // west to east (CCW)
    this.southTiles = [];
    this.eastMeshes = []; // south to north (CCW)
    this.eastTiles = [];
    this.northMeshes = []; // east to west (CCW)
    this.northTiles = [];
    this.southwestMesh = undefined;
    this.southwestTile = undefined;
    this.southeastMesh = undefined;
    this.southeastTile = undefined;
    this.northwestMesh = undefined;
    this.northwestTile = undefined;
    this.northeastMesh = undefined;
    this.northeastTile = undefined;
    this.changedThisFrame = true;
    this.visitedFrame = undefined;
    this.enqueuedFrame = undefined;
    this.mesh = undefined;
    this.vertexArray = undefined;
    this.waterMaskTexture = undefined;
    this.waterMaskTranslationAndScale = new Cartesian4();
  }

  TerrainFillMesh.prototype.update = function (
    tileProvider,
    frameState,
    vertexArraysToDestroy
  ) {
    if (this.changedThisFrame) {
      createFillMesh(tileProvider, frameState, this.tile, vertexArraysToDestroy);
      this.changedThisFrame = false;
    }
  };

  TerrainFillMesh.prototype.destroy = function (vertexArraysToDestroy) {
    if (defined(this.vertexArray)) {
      if (defined(vertexArraysToDestroy)) {
        vertexArraysToDestroy.push(this.vertexArray);
      } else {
        GlobeSurfaceTile._freeVertexArray(
          this.vertexArray,
          vertexArraysToDestroy
        );
      }
      this.vertexArray = undefined;
    }

    if (defined(this.waterMaskTexture)) {
      --this.waterMaskTexture.referenceCount;
      if (this.waterMaskTexture.referenceCount === 0) {
        this.waterMaskTexture.destroy();
      }
      this.waterMaskTexture = undefined;
    }

    return undefined;
  };

  var traversalQueueScratch = new Queue();

  TerrainFillMesh.updateFillTiles = function (
    tileProvider,
    renderedTiles,
    frameState,
    vertexArraysToDestroy
  ) {
    // We want our fill tiles to look natural, which means they should align perfectly with
    // adjacent loaded tiles, and their edges that are not adjacent to loaded tiles should have
    // sensible heights (e.g. the average of the heights of loaded edges). Some fill tiles may
    // be adjacent only to other fill tiles, and in that case heights should be assigned fanning
    // outward from the loaded tiles so that there are no sudden changes in height.

    // We do this with a breadth-first traversal of the rendered tiles, starting with the loaded
    // ones. Graph nodes are tiles and graph edges connect to other rendered tiles that are spatially adjacent
    // to those tiles. As we visit each node, we propagate tile edges to adjacent tiles. If there's no data
    // for a tile edge,  we create an edge with an average height and then propagate it. If an edge is partially defined
    // (e.g. an edge is adjacent to multiple more-detailed tiles and only some of them are loaded), we
    // fill in the rest of the edge with the same height.
    var quadtree = tileProvider._quadtree;
    var levelZeroTiles = quadtree._levelZeroTiles;
    var lastSelectionFrameNumber = quadtree._lastSelectionFrameNumber;

    var traversalQueue = traversalQueueScratch;
    traversalQueue.clear();

    // Add the tiles with real geometry to the traversal queue.
    for (var i = 0; i < renderedTiles.length; ++i) {
      var renderedTile = renderedTiles[i];
      if (defined(renderedTile.data.vertexArray)) {
        traversalQueue.enqueue(renderedTiles[i]);
      }
    }

    var tile = traversalQueue.dequeue();

    while (tile !== undefined) {
      var tileToWest = tile.findTileToWest(levelZeroTiles);
      var tileToSouth = tile.findTileToSouth(levelZeroTiles);
      var tileToEast = tile.findTileToEast(levelZeroTiles);
      var tileToNorth = tile.findTileToNorth(levelZeroTiles);
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToWest,
        lastSelectionFrameNumber,
        TileEdge.EAST,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToSouth,
        lastSelectionFrameNumber,
        TileEdge.NORTH,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToEast,
        lastSelectionFrameNumber,
        TileEdge.WEST,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToNorth,
        lastSelectionFrameNumber,
        TileEdge.SOUTH,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );

      var tileToNorthwest = tileToWest.findTileToNorth(levelZeroTiles);
      var tileToSouthwest = tileToWest.findTileToSouth(levelZeroTiles);
      var tileToNortheast = tileToEast.findTileToNorth(levelZeroTiles);
      var tileToSoutheast = tileToEast.findTileToSouth(levelZeroTiles);
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToNorthwest,
        lastSelectionFrameNumber,
        TileEdge.SOUTHEAST,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToNortheast,
        lastSelectionFrameNumber,
        TileEdge.SOUTHWEST,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToSouthwest,
        lastSelectionFrameNumber,
        TileEdge.NORTHEAST,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );
      visitRenderedTiles(
        tileProvider,
        frameState,
        tile,
        tileToSoutheast,
        lastSelectionFrameNumber,
        TileEdge.NORTHWEST,
        false,
        traversalQueue,
        vertexArraysToDestroy
      );

      tile = traversalQueue.dequeue();
    }
  };

  function visitRenderedTiles(
    tileProvider,
    frameState,
    sourceTile,
    startTile,
    currentFrameNumber,
    tileEdge,
    downOnly,
    traversalQueue,
    vertexArraysToDestroy
  ) {
    if (startTile === undefined) {
      // There are no tiles North or South of the poles.
      return;
    }

    var tile = startTile;
    while (
      tile &&
      (tile._lastSelectionResultFrame !== currentFrameNumber ||
        TileSelectionResult.wasKicked(tile._lastSelectionResult) ||
        TileSelectionResult.originalResult(tile._lastSelectionResult) ===
          TileSelectionResult.CULLED)
    ) {
      // This tile wasn't visited or it was visited and then kicked, so walk up to find the closest ancestor that was rendered.
      // We also walk up if the tile was culled, because if siblings were kicked an ancestor may have been rendered.
      if (downOnly) {
        return;
      }

      var parent = tile.parent;
      if (tileEdge >= TileEdge.NORTHWEST && parent !== undefined) {
        // When we're looking for a corner, verify that the parent tile is still relevant.
        // That is, the parent and child must share the corner in question.
        switch (tileEdge) {
          case TileEdge.NORTHWEST:
            tile = tile === parent.northwestChild ? parent : undefined;
            break;
          case TileEdge.NORTHEAST:
            tile = tile === parent.northeastChild ? parent : undefined;
            break;
          case TileEdge.SOUTHWEST:
            tile = tile === parent.southwestChild ? parent : undefined;
            break;
          case TileEdge.SOUTHEAST:
            tile = tile === parent.southeastChild ? parent : undefined;
            break;
        }
      } else {
        tile = parent;
      }
    }

    if (tile === undefined) {
      return;
    }

    if (tile._lastSelectionResult === TileSelectionResult.RENDERED) {
      if (defined(tile.data.vertexArray)) {
        // No further processing necessary for renderable tiles.
        return;
      }
      visitTile$2(
        tileProvider,
        frameState,
        sourceTile,
        tile,
        tileEdge,
        currentFrameNumber,
        traversalQueue,
        vertexArraysToDestroy
      );
      return;
    }

    if (
      TileSelectionResult.originalResult(startTile._lastSelectionResult) ===
      TileSelectionResult.CULLED
    ) {
      return;
    }

    // This tile was refined, so find rendered children, if any.
    // Visit the tiles in counter-clockwise order.
    switch (tileEdge) {
      case TileEdge.WEST:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.northwestChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.southwestChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.EAST:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.southeastChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.northeastChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.SOUTH:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.southwestChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.southeastChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.NORTH:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.northeastChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.northwestChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.NORTHWEST:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.northwestChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.NORTHEAST:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.northeastChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.SOUTHWEST:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.southwestChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      case TileEdge.SOUTHEAST:
        visitRenderedTiles(
          tileProvider,
          frameState,
          sourceTile,
          startTile.southeastChild,
          currentFrameNumber,
          tileEdge,
          true,
          traversalQueue,
          vertexArraysToDestroy
        );
        break;
      default:
        throw new DeveloperError("Invalid edge");
    }
  }

  function visitTile$2(
    tileProvider,
    frameState,
    sourceTile,
    destinationTile,
    tileEdge,
    frameNumber,
    traversalQueue,
    vertexArraysToDestroy
  ) {
    var destinationSurfaceTile = destinationTile.data;

    if (destinationSurfaceTile.fill === undefined) {
      destinationSurfaceTile.fill = new TerrainFillMesh(destinationTile);
    } else if (destinationSurfaceTile.fill.visitedFrame === frameNumber) {
      // Don't propagate edges to tiles that have already been visited this frame.
      return;
    }

    if (destinationSurfaceTile.fill.enqueuedFrame !== frameNumber) {
      // First time visiting this tile this frame, add it to the traversal queue.
      destinationSurfaceTile.fill.enqueuedFrame = frameNumber;
      destinationSurfaceTile.fill.changedThisFrame = false;
      traversalQueue.enqueue(destinationTile);
    }

    propagateEdge(
      tileProvider,
      frameState,
      sourceTile,
      destinationTile,
      tileEdge,
      vertexArraysToDestroy
    );
  }

  function propagateEdge(
    tileProvider,
    frameState,
    sourceTile,
    destinationTile,
    tileEdge,
    vertexArraysToDestroy
  ) {
    var destinationFill = destinationTile.data.fill;

    var sourceMesh;
    var sourceFill = sourceTile.data.fill;
    if (defined(sourceFill)) {
      sourceFill.visitedFrame = frameState.frameNumber;

      // Source is a fill, create/update it if necessary.
      if (sourceFill.changedThisFrame) {
        createFillMesh(
          tileProvider,
          frameState,
          sourceTile,
          vertexArraysToDestroy
        );
        sourceFill.changedThisFrame = false;
      }
      sourceMesh = sourceTile.data.fill.mesh;
    } else {
      sourceMesh = sourceTile.data.mesh;
    }

    var edgeMeshes;
    var edgeTiles;

    switch (tileEdge) {
      case TileEdge.WEST:
        edgeMeshes = destinationFill.westMeshes;
        edgeTiles = destinationFill.westTiles;
        break;
      case TileEdge.SOUTH:
        edgeMeshes = destinationFill.southMeshes;
        edgeTiles = destinationFill.southTiles;
        break;
      case TileEdge.EAST:
        edgeMeshes = destinationFill.eastMeshes;
        edgeTiles = destinationFill.eastTiles;
        break;
      case TileEdge.NORTH:
        edgeMeshes = destinationFill.northMeshes;
        edgeTiles = destinationFill.northTiles;
        break;
      // Corners are simpler.
      case TileEdge.NORTHWEST:
        destinationFill.changedThisFrame =
          destinationFill.changedThisFrame ||
          destinationFill.northwestMesh !== sourceMesh;
        destinationFill.northwestMesh = sourceMesh;
        destinationFill.northwestTile = sourceTile;
        return;
      case TileEdge.NORTHEAST:
        destinationFill.changedThisFrame =
          destinationFill.changedThisFrame ||
          destinationFill.northeastMesh !== sourceMesh;
        destinationFill.northeastMesh = sourceMesh;
        destinationFill.northeastTile = sourceTile;
        return;
      case TileEdge.SOUTHWEST:
        destinationFill.changedThisFrame =
          destinationFill.changedThisFrame ||
          destinationFill.southwestMesh !== sourceMesh;
        destinationFill.southwestMesh = sourceMesh;
        destinationFill.southwestTile = sourceTile;
        return;
      case TileEdge.SOUTHEAST:
        destinationFill.changedThisFrame =
          destinationFill.changedThisFrame ||
          destinationFill.southeastMesh !== sourceMesh;
        destinationFill.southeastMesh = sourceMesh;
        destinationFill.southeastTile = sourceTile;
        return;
    }

    if (sourceTile.level <= destinationTile.level) {
      // Source edge completely spans the destination edge.
      destinationFill.changedThisFrame =
        destinationFill.changedThisFrame ||
        edgeMeshes[0] !== sourceMesh ||
        edgeMeshes.length !== 1;
      edgeMeshes[0] = sourceMesh;
      edgeTiles[0] = sourceTile;
      edgeMeshes.length = 1;
      edgeTiles.length = 1;
      return;
    }

    // Source edge is a subset of the destination edge.
    // Figure out the range of meshes we're replacing.
    var startIndex, endIndex, existingTile, existingRectangle;
    var sourceRectangle = sourceTile.rectangle;

    var epsilon;
    var destinationRectangle = destinationTile.rectangle;

    switch (tileEdge) {
      case TileEdge.WEST:
        epsilon =
          (destinationRectangle.north - destinationRectangle.south) *
          CesiumMath.EPSILON5;

        for (startIndex = 0; startIndex < edgeTiles.length; ++startIndex) {
          existingTile = edgeTiles[startIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.greaterThan(
              sourceRectangle.north,
              existingRectangle.south,
              epsilon
            )
          ) {
            break;
          }
        }
        for (endIndex = startIndex; endIndex < edgeTiles.length; ++endIndex) {
          existingTile = edgeTiles[endIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.greaterThanOrEquals(
              sourceRectangle.south,
              existingRectangle.north,
              epsilon
            )
          ) {
            break;
          }
        }
        break;
      case TileEdge.SOUTH:
        epsilon =
          (destinationRectangle.east - destinationRectangle.west) *
          CesiumMath.EPSILON5;

        for (startIndex = 0; startIndex < edgeTiles.length; ++startIndex) {
          existingTile = edgeTiles[startIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.lessThan(
              sourceRectangle.west,
              existingRectangle.east,
              epsilon
            )
          ) {
            break;
          }
        }
        for (endIndex = startIndex; endIndex < edgeTiles.length; ++endIndex) {
          existingTile = edgeTiles[endIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.lessThanOrEquals(
              sourceRectangle.east,
              existingRectangle.west,
              epsilon
            )
          ) {
            break;
          }
        }
        break;
      case TileEdge.EAST:
        epsilon =
          (destinationRectangle.north - destinationRectangle.south) *
          CesiumMath.EPSILON5;

        for (startIndex = 0; startIndex < edgeTiles.length; ++startIndex) {
          existingTile = edgeTiles[startIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.lessThan(
              sourceRectangle.south,
              existingRectangle.north,
              epsilon
            )
          ) {
            break;
          }
        }
        for (endIndex = startIndex; endIndex < edgeTiles.length; ++endIndex) {
          existingTile = edgeTiles[endIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.lessThanOrEquals(
              sourceRectangle.north,
              existingRectangle.south,
              epsilon
            )
          ) {
            break;
          }
        }
        break;
      case TileEdge.NORTH:
        epsilon =
          (destinationRectangle.east - destinationRectangle.west) *
          CesiumMath.EPSILON5;

        for (startIndex = 0; startIndex < edgeTiles.length; ++startIndex) {
          existingTile = edgeTiles[startIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.greaterThan(
              sourceRectangle.east,
              existingRectangle.west,
              epsilon
            )
          ) {
            break;
          }
        }
        for (endIndex = startIndex; endIndex < edgeTiles.length; ++endIndex) {
          existingTile = edgeTiles[endIndex];
          existingRectangle = existingTile.rectangle;
          if (
            CesiumMath.greaterThanOrEquals(
              sourceRectangle.west,
              existingRectangle.east,
              epsilon
            )
          ) {
            break;
          }
        }
        break;
    }

    if (endIndex - startIndex === 1) {
      destinationFill.changedThisFrame =
        destinationFill.changedThisFrame || edgeMeshes[startIndex] !== sourceMesh;
      edgeMeshes[startIndex] = sourceMesh;
      edgeTiles[startIndex] = sourceTile;
    } else {
      destinationFill.changedThisFrame = true;
      edgeMeshes.splice(startIndex, endIndex - startIndex, sourceMesh);
      edgeTiles.splice(startIndex, endIndex - startIndex, sourceTile);
    }
  }

  var cartographicScratch$3 = new Cartographic();
  var centerCartographicScratch = new Cartographic();
  var cartesianScratch = new Cartesian3();
  var normalScratch$5 = new Cartesian3();
  var octEncodedNormalScratch = new Cartesian2();
  var uvScratch2 = new Cartesian2();
  var uvScratch = new Cartesian2();

  function HeightAndNormal() {
    this.height = 0.0;
    this.encodedNormal = new Cartesian2();
  }

  function fillMissingCorner(
    fill,
    ellipsoid,
    u,
    v,
    corner,
    adjacentCorner1,
    adjacentCorner2,
    oppositeCorner,
    vertex
  ) {
    if (defined(corner)) {
      return corner;
    }

    var height;

    if (defined(adjacentCorner1) && defined(adjacentCorner2)) {
      height = (adjacentCorner1.height + adjacentCorner2.height) * 0.5;
    } else if (defined(adjacentCorner1)) {
      height = adjacentCorner1.height;
    } else if (defined(adjacentCorner2)) {
      height = adjacentCorner2.height;
    } else if (defined(oppositeCorner)) {
      height = oppositeCorner.height;
    } else {
      var surfaceTile = fill.tile.data;
      var tileBoundingRegion = surfaceTile.tileBoundingRegion;
      var minimumHeight = 0.0;
      var maximumHeight = 0.0;
      if (defined(tileBoundingRegion)) {
        minimumHeight = tileBoundingRegion.minimumHeight;
        maximumHeight = tileBoundingRegion.maximumHeight;
      }
      height = (minimumHeight + maximumHeight) * 0.5;
    }

    getVertexWithHeightAtCorner(fill, ellipsoid, u, v, height, vertex);
    return vertex;
  }

  var heightRangeScratch = {
    minimumHeight: 0.0,
    maximumHeight: 0.0,
  };

  var swVertexScratch = new HeightAndNormal();
  var seVertexScratch = new HeightAndNormal();
  var nwVertexScratch = new HeightAndNormal();
  var neVertexScratch = new HeightAndNormal();
  var heightmapBuffer =
    typeof Uint8Array !== "undefined" ? new Uint8Array(9 * 9) : undefined;

  function createFillMesh(tileProvider, frameState, tile, vertexArraysToDestroy) {
    GlobeSurfaceTile.initialize(
      tile,
      tileProvider.terrainProvider,
      tileProvider._imageryLayers
    );

    var surfaceTile = tile.data;
    var fill = surfaceTile.fill;
    var rectangle = tile.rectangle;

    var ellipsoid = tile.tilingScheme.ellipsoid;

    var nwCorner = getCorner(
      fill,
      ellipsoid,
      0.0,
      1.0,
      fill.northwestTile,
      fill.northwestMesh,
      fill.northTiles,
      fill.northMeshes,
      fill.westTiles,
      fill.westMeshes,
      nwVertexScratch
    );
    var swCorner = getCorner(
      fill,
      ellipsoid,
      0.0,
      0.0,
      fill.southwestTile,
      fill.southwestMesh,
      fill.westTiles,
      fill.westMeshes,
      fill.southTiles,
      fill.southMeshes,
      swVertexScratch
    );
    var seCorner = getCorner(
      fill,
      ellipsoid,
      1.0,
      0.0,
      fill.southeastTile,
      fill.southeastMesh,
      fill.southTiles,
      fill.southMeshes,
      fill.eastTiles,
      fill.eastMeshes,
      seVertexScratch
    );
    var neCorner = getCorner(
      fill,
      ellipsoid,
      1.0,
      1.0,
      fill.northeastTile,
      fill.northeastMesh,
      fill.eastTiles,
      fill.eastMeshes,
      fill.northTiles,
      fill.northMeshes,
      neVertexScratch
    );

    nwCorner = fillMissingCorner(
      fill,
      ellipsoid,
      0.0,
      1.0,
      nwCorner,
      swCorner,
      neCorner,
      seCorner,
      nwVertexScratch
    );
    swCorner = fillMissingCorner(
      fill,
      ellipsoid,
      0.0,
      0.0,
      swCorner,
      nwCorner,
      seCorner,
      neCorner,
      swVertexScratch
    );
    seCorner = fillMissingCorner(
      fill,
      ellipsoid,
      1.0,
      1.0,
      seCorner,
      swCorner,
      neCorner,
      nwCorner,
      seVertexScratch
    );
    neCorner = fillMissingCorner(
      fill,
      ellipsoid,
      1.0,
      1.0,
      neCorner,
      seCorner,
      nwCorner,
      swCorner,
      neVertexScratch
    );

    var southwestHeight = swCorner.height;
    var southeastHeight = seCorner.height;
    var northwestHeight = nwCorner.height;
    var northeastHeight = neCorner.height;

    var minimumHeight = Math.min(
      southwestHeight,
      southeastHeight,
      northwestHeight,
      northeastHeight
    );
    var maximumHeight = Math.max(
      southwestHeight,
      southeastHeight,
      northwestHeight,
      northeastHeight
    );

    var middleHeight = (minimumHeight + maximumHeight) * 0.5;

    var i;
    var len;

    // For low-detail tiles, our usual fill tile approach will create tiles that
    // look really blocky because they don't have enough vertices to account for the
    // Earth's curvature. But the height range will also typically be well within
    // the allowed geometric error for those levels. So fill such tiles with a
    // constant-height heightmap.
    var geometricError = tileProvider.getLevelMaximumGeometricError(tile.level);
    var minCutThroughRadius = ellipsoid.maximumRadius - geometricError;
    var maxTileWidth =
      Math.acos(minCutThroughRadius / ellipsoid.maximumRadius) * 4.0;

    // When the tile width is greater than maxTileWidth as computed above, the error
    // of a normal fill tile from globe curvature alone will exceed the allowed geometric
    // error. Terrain won't change that much. However, we can allow more error than that.
    // A little blockiness during load is acceptable. For the WGS84 ellipsoid and
    // standard geometric error setup, the value here will have us use a heightmap
    // at levels 1, 2, and 3.
    maxTileWidth *= 1.5;

    if (
      rectangle.width > maxTileWidth &&
      maximumHeight - minimumHeight <= geometricError
    ) {
      var terrainData = new HeightmapTerrainData({
        width: 9,
        height: 9,
        buffer: heightmapBuffer,
        structure: {
          // Use the maximum as the constant height so that this tile's skirt
          // covers any cracks with adjacent tiles.
          heightOffset: maximumHeight,
        },
      });
      fill.mesh = terrainData._createMeshSync(
        tile.tilingScheme,
        tile.x,
        tile.y,
        tile.level,
        1.0
      );
    } else {
      var encoding = new TerrainEncoding(
        undefined,
        undefined,
        undefined,
        undefined,
        true,
        true
      );

      var centerCartographic = centerCartographicScratch;
      centerCartographic.longitude = (rectangle.east + rectangle.west) * 0.5;
      centerCartographic.latitude = (rectangle.north + rectangle.south) * 0.5;
      centerCartographic.height = middleHeight;
      encoding.center = ellipsoid.cartographicToCartesian(
        centerCartographic,
        encoding.center
      );

      // At _most_, we have vertices for the 4 corners, plus 1 center, plus every adjacent edge vertex.
      // In reality there will be less most of the time, but close enough; better
      // to overestimate than to re-allocate/copy/traverse the vertices twice.
      // Also, we'll often be able to squeeze the index data into the extra space in the buffer.
      var maxVertexCount = 5;
      var meshes;

      meshes = fill.westMeshes;
      for (i = 0, len = meshes.length; i < len; ++i) {
        maxVertexCount += meshes[i].eastIndicesNorthToSouth.length;
      }

      meshes = fill.southMeshes;
      for (i = 0, len = meshes.length; i < len; ++i) {
        maxVertexCount += meshes[i].northIndicesWestToEast.length;
      }

      meshes = fill.eastMeshes;
      for (i = 0, len = meshes.length; i < len; ++i) {
        maxVertexCount += meshes[i].westIndicesSouthToNorth.length;
      }

      meshes = fill.northMeshes;
      for (i = 0, len = meshes.length; i < len; ++i) {
        maxVertexCount += meshes[i].southIndicesEastToWest.length;
      }

      var heightRange = heightRangeScratch;
      heightRange.minimumHeight = minimumHeight;
      heightRange.maximumHeight = maximumHeight;

      var stride = encoding.getStride();
      var typedArray = new Float32Array(maxVertexCount * stride);

      var nextIndex = 0;
      var northwestIndex = nextIndex;
      nextIndex = addVertexWithComputedPosition(
        ellipsoid,
        rectangle,
        encoding,
        typedArray,
        nextIndex,
        0.0,
        1.0,
        nwCorner.height,
        nwCorner.encodedNormal,
        1.0,
        heightRange
      );
      nextIndex = addEdge(
        fill,
        ellipsoid,
        encoding,
        typedArray,
        nextIndex,
        fill.westTiles,
        fill.westMeshes,
        TileEdge.EAST,
        heightRange
      );
      var southwestIndex = nextIndex;
      nextIndex = addVertexWithComputedPosition(
        ellipsoid,
        rectangle,
        encoding,
        typedArray,
        nextIndex,
        0.0,
        0.0,
        swCorner.height,
        swCorner.encodedNormal,
        0.0,
        heightRange
      );
      nextIndex = addEdge(
        fill,
        ellipsoid,
        encoding,
        typedArray,
        nextIndex,
        fill.southTiles,
        fill.southMeshes,
        TileEdge.NORTH,
        heightRange
      );
      var southeastIndex = nextIndex;
      nextIndex = addVertexWithComputedPosition(
        ellipsoid,
        rectangle,
        encoding,
        typedArray,
        nextIndex,
        1.0,
        0.0,
        seCorner.height,
        seCorner.encodedNormal,
        0.0,
        heightRange
      );
      nextIndex = addEdge(
        fill,
        ellipsoid,
        encoding,
        typedArray,
        nextIndex,
        fill.eastTiles,
        fill.eastMeshes,
        TileEdge.WEST,
        heightRange
      );
      var northeastIndex = nextIndex;
      nextIndex = addVertexWithComputedPosition(
        ellipsoid,
        rectangle,
        encoding,
        typedArray,
        nextIndex,
        1.0,
        1.0,
        neCorner.height,
        neCorner.encodedNormal,
        1.0,
        heightRange
      );
      nextIndex = addEdge(
        fill,
        ellipsoid,
        encoding,
        typedArray,
        nextIndex,
        fill.northTiles,
        fill.northMeshes,
        TileEdge.SOUTH,
        heightRange
      );

      minimumHeight = heightRange.minimumHeight;
      maximumHeight = heightRange.maximumHeight;

      var obb = OrientedBoundingBox.fromRectangle(
        rectangle,
        minimumHeight,
        maximumHeight,
        tile.tilingScheme.ellipsoid
      );

      // Add a single vertex at the center of the tile.
      var southMercatorY = WebMercatorProjection.geodeticLatitudeToMercatorAngle(
        rectangle.south
      );
      var oneOverMercatorHeight =
        1.0 /
        (WebMercatorProjection.geodeticLatitudeToMercatorAngle(rectangle.north) -
          southMercatorY);
      var centerWebMercatorT =
        (WebMercatorProjection.geodeticLatitudeToMercatorAngle(
          centerCartographic.latitude
        ) -
          southMercatorY) *
        oneOverMercatorHeight;

      ellipsoid.geodeticSurfaceNormalCartographic(
        cartographicScratch$3,
        normalScratch$5
      );
      var centerEncodedNormal = AttributeCompression.octEncode(
        normalScratch$5,
        octEncodedNormalScratch
      );

      var centerIndex = nextIndex;
      encoding.encode(
        typedArray,
        nextIndex * stride,
        obb.center,
        Cartesian2.fromElements(0.5, 0.5, uvScratch),
        middleHeight,
        centerEncodedNormal,
        centerWebMercatorT
      );
      ++nextIndex;

      var vertexCount = nextIndex;

      var bytesPerIndex = vertexCount < 256 ? 1 : 2;
      var indexCount = (vertexCount - 1) * 3; // one triangle per edge vertex
      var indexDataBytes = indexCount * bytesPerIndex;
      var availableBytesInBuffer =
        (typedArray.length - vertexCount * stride) *
        Float32Array.BYTES_PER_ELEMENT;

      var indices;
      if (availableBytesInBuffer >= indexDataBytes) {
        // Store the index data in the same buffer as the vertex data.
        var startIndex = vertexCount * stride * Float32Array.BYTES_PER_ELEMENT;
        indices =
          vertexCount < 256
            ? new Uint8Array(typedArray.buffer, startIndex, indexCount)
            : new Uint16Array(typedArray.buffer, startIndex, indexCount);
      } else {
        // Allocate a new buffer for the index data.
        indices =
          vertexCount < 256
            ? new Uint8Array(indexCount)
            : new Uint16Array(indexCount);
      }

      typedArray = new Float32Array(typedArray.buffer, 0, vertexCount * stride);

      var indexOut = 0;
      for (i = 0; i < vertexCount - 2; ++i) {
        indices[indexOut++] = centerIndex;
        indices[indexOut++] = i;
        indices[indexOut++] = i + 1;
      }

      indices[indexOut++] = centerIndex;
      indices[indexOut++] = i;
      indices[indexOut++] = 0;

      var westIndicesSouthToNorth = [];
      for (i = southwestIndex; i >= northwestIndex; --i) {
        westIndicesSouthToNorth.push(i);
      }

      var southIndicesEastToWest = [];
      for (i = southeastIndex; i >= southwestIndex; --i) {
        southIndicesEastToWest.push(i);
      }

      var eastIndicesNorthToSouth = [];
      for (i = northeastIndex; i >= southeastIndex; --i) {
        eastIndicesNorthToSouth.push(i);
      }

      var northIndicesWestToEast = [];
      northIndicesWestToEast.push(0);
      for (i = centerIndex - 1; i >= northeastIndex; --i) {
        northIndicesWestToEast.push(i);
      }

      fill.mesh = new TerrainMesh(
        encoding.center,
        typedArray,
        indices,
        indexCount,
        vertexCount,
        minimumHeight,
        maximumHeight,
        BoundingSphere.fromOrientedBoundingBox(obb),
        computeOccludeePoint(
          tileProvider,
          obb.center,
          rectangle,
          minimumHeight,
          maximumHeight
        ),
        encoding.getStride(),
        obb,
        encoding,
        frameState.terrainExaggeration,
        westIndicesSouthToNorth,
        southIndicesEastToWest,
        eastIndicesNorthToSouth,
        northIndicesWestToEast
      );
    }

    var context = frameState.context;

    if (defined(fill.vertexArray)) {
      if (defined(vertexArraysToDestroy)) {
        vertexArraysToDestroy.push(fill.vertexArray);
      } else {
        GlobeSurfaceTile._freeVertexArray(fill.vertexArray);
      }
    }

    fill.vertexArray = GlobeSurfaceTile._createVertexArrayForMesh(
      context,
      fill.mesh
    );
    surfaceTile.processImagery(
      tile,
      tileProvider.terrainProvider,
      frameState,
      true
    );

    var oldTexture = fill.waterMaskTexture;
    fill.waterMaskTexture = undefined;

    if (tileProvider.terrainProvider.hasWaterMask) {
      var waterSourceTile = surfaceTile._findAncestorTileWithTerrainData(tile);
      if (
        defined(waterSourceTile) &&
        defined(waterSourceTile.data.waterMaskTexture)
      ) {
        fill.waterMaskTexture = waterSourceTile.data.waterMaskTexture;
        ++fill.waterMaskTexture.referenceCount;
        surfaceTile._computeWaterMaskTranslationAndScale(
          tile,
          waterSourceTile,
          fill.waterMaskTranslationAndScale
        );
      }
    }

    if (defined(oldTexture)) {
      --oldTexture.referenceCount;
      if (oldTexture.referenceCount === 0) {
        oldTexture.destroy();
      }
    }
  }

  function addVertexWithComputedPosition(
    ellipsoid,
    rectangle,
    encoding,
    buffer,
    index,
    u,
    v,
    height,
    encodedNormal,
    webMercatorT,
    heightRange
  ) {
    var cartographic = cartographicScratch$3;
    cartographic.longitude = CesiumMath.lerp(rectangle.west, rectangle.east, u);
    cartographic.latitude = CesiumMath.lerp(rectangle.south, rectangle.north, v);
    cartographic.height = height;
    var position = ellipsoid.cartographicToCartesian(
      cartographic,
      cartesianScratch
    );

    var uv = uvScratch2;
    uv.x = u;
    uv.y = v;

    encoding.encode(
      buffer,
      index * encoding.getStride(),
      position,
      uv,
      height,
      encodedNormal,
      webMercatorT
    );

    heightRange.minimumHeight = Math.min(heightRange.minimumHeight, height);
    heightRange.maximumHeight = Math.max(heightRange.maximumHeight, height);

    return index + 1;
  }

  var sourceRectangleScratch = new Rectangle();

  function transformTextureCoordinates(
    sourceTile,
    targetTile,
    coordinates,
    result
  ) {
    var sourceRectangle = sourceTile.rectangle;
    var targetRectangle = targetTile.rectangle;

    // Handle transforming across the anti-meridian.
    if (
      targetTile.x === 0 &&
      coordinates.x === 1.0 &&
      sourceTile.x ===
        sourceTile.tilingScheme.getNumberOfXTilesAtLevel(sourceTile.level) - 1
    ) {
      sourceRectangle = Rectangle.clone(
        sourceTile.rectangle,
        sourceRectangleScratch
      );
      sourceRectangle.west -= CesiumMath.TWO_PI;
      sourceRectangle.east -= CesiumMath.TWO_PI;
    } else if (
      sourceTile.x === 0 &&
      coordinates.x === 0.0 &&
      targetTile.x ===
        targetTile.tilingScheme.getNumberOfXTilesAtLevel(targetTile.level) - 1
    ) {
      sourceRectangle = Rectangle.clone(
        sourceTile.rectangle,
        sourceRectangleScratch
      );
      sourceRectangle.west += CesiumMath.TWO_PI;
      sourceRectangle.east += CesiumMath.TWO_PI;
    }

    var sourceWidth = sourceRectangle.east - sourceRectangle.west;
    var umin = (targetRectangle.west - sourceRectangle.west) / sourceWidth;
    var umax = (targetRectangle.east - sourceRectangle.west) / sourceWidth;

    var sourceHeight = sourceRectangle.north - sourceRectangle.south;
    var vmin = (targetRectangle.south - sourceRectangle.south) / sourceHeight;
    var vmax = (targetRectangle.north - sourceRectangle.south) / sourceHeight;

    var u = (coordinates.x - umin) / (umax - umin);
    var v = (coordinates.y - vmin) / (vmax - vmin);

    // Ensure that coordinates very near the corners are at the corners.
    if (Math.abs(u) < Math.EPSILON5) {
      u = 0.0;
    } else if (Math.abs(u - 1.0) < Math.EPSILON5) {
      u = 1.0;
    }

    if (Math.abs(v) < Math.EPSILON5) {
      v = 0.0;
    } else if (Math.abs(v - 1.0) < Math.EPSILON5) {
      v = 1.0;
    }

    result.x = u;
    result.y = v;
    return result;
  }

  var encodedNormalScratch = new Cartesian2();

  function getVertexFromTileAtCorner(sourceMesh, sourceIndex, u, v, vertex) {
    var sourceEncoding = sourceMesh.encoding;
    var sourceVertices = sourceMesh.vertices;

    vertex.height = sourceEncoding.decodeHeight(sourceVertices, sourceIndex);

    if (sourceEncoding.hasVertexNormals) {
      sourceEncoding.getOctEncodedNormal(
        sourceVertices,
        sourceIndex,
        vertex.encodedNormal
      );
    } else {
      var normal = vertex.encodedNormal;
      normal.x = 0.0;
      normal.y = 0.0;
    }
  }

  var encodedNormalScratch2 = new Cartesian2();
  var cartesianScratch2 = new Cartesian3();

  function getInterpolatedVertexAtCorner(
    ellipsoid,
    sourceTile,
    targetTile,
    sourceMesh,
    previousIndex,
    nextIndex,
    u,
    v,
    interpolateU,
    vertex
  ) {
    var sourceEncoding = sourceMesh.encoding;
    var sourceVertices = sourceMesh.vertices;

    var previousUv = transformTextureCoordinates(
      sourceTile,
      targetTile,
      sourceEncoding.decodeTextureCoordinates(
        sourceVertices,
        previousIndex,
        uvScratch
      ),
      uvScratch
    );
    var nextUv = transformTextureCoordinates(
      sourceTile,
      targetTile,
      sourceEncoding.decodeTextureCoordinates(
        sourceVertices,
        nextIndex,
        uvScratch2
      ),
      uvScratch2
    );

    var ratio;
    if (interpolateU) {
      ratio = (u - previousUv.x) / (nextUv.x - previousUv.x);
    } else {
      ratio = (v - previousUv.y) / (nextUv.y - previousUv.y);
    }

    var height1 = sourceEncoding.decodeHeight(sourceVertices, previousIndex);
    var height2 = sourceEncoding.decodeHeight(sourceVertices, nextIndex);

    var targetRectangle = targetTile.rectangle;
    cartographicScratch$3.longitude = CesiumMath.lerp(
      targetRectangle.west,
      targetRectangle.east,
      u
    );
    cartographicScratch$3.latitude = CesiumMath.lerp(
      targetRectangle.south,
      targetRectangle.north,
      v
    );
    vertex.height = cartographicScratch$3.height = CesiumMath.lerp(
      height1,
      height2,
      ratio
    );

    var normal;
    if (sourceEncoding.hasVertexNormals) {
      var encodedNormal1 = sourceEncoding.getOctEncodedNormal(
        sourceVertices,
        previousIndex,
        encodedNormalScratch
      );
      var encodedNormal2 = sourceEncoding.getOctEncodedNormal(
        sourceVertices,
        nextIndex,
        encodedNormalScratch2
      );
      var normal1 = AttributeCompression.octDecode(
        encodedNormal1.x,
        encodedNormal1.y,
        cartesianScratch
      );
      var normal2 = AttributeCompression.octDecode(
        encodedNormal2.x,
        encodedNormal2.y,
        cartesianScratch2
      );
      normal = Cartesian3.lerp(normal1, normal2, ratio, cartesianScratch);
      Cartesian3.normalize(normal, normal);
      AttributeCompression.octEncode(normal, vertex.encodedNormal);
    } else {
      normal = ellipsoid.geodeticSurfaceNormalCartographic(
        cartographicScratch$3,
        cartesianScratch
      );
      AttributeCompression.octEncode(normal, vertex.encodedNormal);
    }
  }

  function getVertexWithHeightAtCorner(
    terrainFillMesh,
    ellipsoid,
    u,
    v,
    height,
    vertex
  ) {
    vertex.height = height;
    var normal = ellipsoid.geodeticSurfaceNormalCartographic(
      cartographicScratch$3,
      cartesianScratch
    );
    AttributeCompression.octEncode(normal, vertex.encodedNormal);
  }

  function getCorner(
    terrainFillMesh,
    ellipsoid,
    u,
    v,
    cornerTile,
    cornerMesh,
    previousEdgeTiles,
    previousEdgeMeshes,
    nextEdgeTiles,
    nextEdgeMeshes,
    vertex
  ) {
    var gotCorner =
      getCornerFromEdge(
        terrainFillMesh,
        ellipsoid,
        previousEdgeMeshes,
        previousEdgeTiles,
        false,
        u,
        v,
        vertex
      ) ||
      getCornerFromEdge(
        terrainFillMesh,
        ellipsoid,
        nextEdgeMeshes,
        nextEdgeTiles,
        true,
        u,
        v,
        vertex
      );
    if (gotCorner) {
      return vertex;
    }

    var vertexIndex;

    if (meshIsUsable(cornerTile, cornerMesh)) {
      // Corner mesh is valid, copy its corner vertex to this mesh.
      if (u === 0.0) {
        if (v === 0.0) {
          // southwest destination, northeast source
          vertexIndex = cornerMesh.eastIndicesNorthToSouth[0];
        } else {
          // northwest destination, southeast source
          vertexIndex = cornerMesh.southIndicesEastToWest[0];
        }
      } else if (v === 0.0) {
        // southeast destination, northwest source
        vertexIndex = cornerMesh.northIndicesWestToEast[0];
      } else {
        // northeast destination, southwest source
        vertexIndex = cornerMesh.westIndicesSouthToNorth[0];
      }
      getVertexFromTileAtCorner(cornerMesh, vertexIndex, u, v, vertex);
      return vertex;
    }

    // There is no precise vertex available from the corner or from either adjacent edge.
    // This is either because there are no tiles at all at the edges and corner, or
    // because the tiles at the edge are higher-level-number and don't extend all the way
    // to the corner.
    // Try to grab a height from the adjacent edges.
    var height;
    if (u === 0.0) {
      if (v === 0.0) {
        // southwest
        height = getClosestHeightToCorner(
          terrainFillMesh.westMeshes,
          terrainFillMesh.westTiles,
          TileEdge.EAST,
          terrainFillMesh.southMeshes,
          terrainFillMesh.southTiles,
          TileEdge.NORTH);
      } else {
        // northwest
        height = getClosestHeightToCorner(
          terrainFillMesh.northMeshes,
          terrainFillMesh.northTiles,
          TileEdge.SOUTH,
          terrainFillMesh.westMeshes,
          terrainFillMesh.westTiles,
          TileEdge.EAST);
      }
    } else if (v === 0.0) {
      // southeast
      height = getClosestHeightToCorner(
        terrainFillMesh.southMeshes,
        terrainFillMesh.southTiles,
        TileEdge.NORTH,
        terrainFillMesh.eastMeshes,
        terrainFillMesh.eastTiles,
        TileEdge.WEST);
    } else {
      // northeast
      height = getClosestHeightToCorner(
        terrainFillMesh.eastMeshes,
        terrainFillMesh.eastTiles,
        TileEdge.WEST,
        terrainFillMesh.northMeshes,
        terrainFillMesh.northTiles,
        TileEdge.SOUTH);
    }

    if (defined(height)) {
      getVertexWithHeightAtCorner(
        terrainFillMesh,
        ellipsoid,
        u,
        v,
        height,
        vertex
      );
      return vertex;
    }

    // No heights available that are closer than the adjacent corners.
    return undefined;
  }

  function getClosestHeightToCorner(
    previousMeshes,
    previousTiles,
    previousEdge,
    nextMeshes,
    nextTiles,
    nextEdge,
    u,
    v
  ) {
    var height1 = getNearestHeightOnEdge(
      previousMeshes,
      previousTiles,
      false,
      previousEdge);
    var height2 = getNearestHeightOnEdge(
      nextMeshes,
      nextTiles,
      true,
      nextEdge);
    if (defined(height1) && defined(height2)) {
      // It would be slightly better to do a weighted average of the two heights
      // based on their distance from the corner, but it shouldn't matter much in practice.
      return (height1 + height2) * 0.5;
    } else if (defined(height1)) {
      return height1;
    }
    return height2;
  }

  function addEdge(
    terrainFillMesh,
    ellipsoid,
    encoding,
    typedArray,
    nextIndex,
    edgeTiles,
    edgeMeshes,
    tileEdge,
    heightRange
  ) {
    for (var i = 0; i < edgeTiles.length; ++i) {
      nextIndex = addEdgeMesh(
        terrainFillMesh,
        ellipsoid,
        encoding,
        typedArray,
        nextIndex,
        edgeTiles[i],
        edgeMeshes[i],
        tileEdge,
        heightRange
      );
    }
    return nextIndex;
  }

  function addEdgeMesh(
    terrainFillMesh,
    ellipsoid,
    encoding,
    typedArray,
    nextIndex,
    edgeTile,
    edgeMesh,
    tileEdge,
    heightRange
  ) {
    // Handle copying edges across the anti-meridian.
    var sourceRectangle = edgeTile.rectangle;
    if (tileEdge === TileEdge.EAST && terrainFillMesh.tile.x === 0) {
      sourceRectangle = Rectangle.clone(
        edgeTile.rectangle,
        sourceRectangleScratch
      );
      sourceRectangle.west -= CesiumMath.TWO_PI;
      sourceRectangle.east -= CesiumMath.TWO_PI;
    } else if (tileEdge === TileEdge.WEST && edgeTile.x === 0) {
      sourceRectangle = Rectangle.clone(
        edgeTile.rectangle,
        sourceRectangleScratch
      );
      sourceRectangle.west += CesiumMath.TWO_PI;
      sourceRectangle.east += CesiumMath.TWO_PI;
    }

    var targetRectangle = terrainFillMesh.tile.rectangle;

    var lastU;
    var lastV;

    if (nextIndex > 0) {
      encoding.decodeTextureCoordinates(typedArray, nextIndex - 1, uvScratch);
      lastU = uvScratch.x;
      lastV = uvScratch.y;
    }

    var indices;
    var compareU;

    switch (tileEdge) {
      case TileEdge.WEST:
        indices = edgeMesh.westIndicesSouthToNorth;
        compareU = false;
        break;
      case TileEdge.NORTH:
        indices = edgeMesh.northIndicesWestToEast;
        compareU = true;
        break;
      case TileEdge.EAST:
        indices = edgeMesh.eastIndicesNorthToSouth;
        compareU = false;
        break;
      case TileEdge.SOUTH:
        indices = edgeMesh.southIndicesEastToWest;
        compareU = true;
        break;
    }

    var sourceTile = edgeTile;
    var targetTile = terrainFillMesh.tile;
    var sourceEncoding = edgeMesh.encoding;
    var sourceVertices = edgeMesh.vertices;
    var targetStride = encoding.getStride();

    var southMercatorY;
    var oneOverMercatorHeight;
    if (sourceEncoding.hasWebMercatorT) {
      southMercatorY = WebMercatorProjection.geodeticLatitudeToMercatorAngle(
        targetRectangle.south
      );
      oneOverMercatorHeight =
        1.0 /
        (WebMercatorProjection.geodeticLatitudeToMercatorAngle(
          targetRectangle.north
        ) -
          southMercatorY);
    }

    for (var i = 0; i < indices.length; ++i) {
      var index = indices[i];

      var uv = sourceEncoding.decodeTextureCoordinates(
        sourceVertices,
        index,
        uvScratch
      );
      transformTextureCoordinates(sourceTile, targetTile, uv, uv);
      var u = uv.x;
      var v = uv.y;
      var uOrV = compareU ? u : v;

      if (uOrV < 0.0 || uOrV > 1.0) {
        // Vertex is outside the target tile - skip it.
        continue;
      }

      if (
        Math.abs(u - lastU) < CesiumMath.EPSILON5 &&
        Math.abs(v - lastV) < CesiumMath.EPSILON5
      ) {
        // Vertex is very close to the previous one - skip it.
        continue;
      }

      var nearlyEdgeU =
        Math.abs(u) < CesiumMath.EPSILON5 ||
        Math.abs(u - 1.0) < CesiumMath.EPSILON5;
      var nearlyEdgeV =
        Math.abs(v) < CesiumMath.EPSILON5 ||
        Math.abs(v - 1.0) < CesiumMath.EPSILON5;

      if (nearlyEdgeU && nearlyEdgeV) {
        // Corner vertex - skip it.
        continue;
      }

      var position = sourceEncoding.decodePosition(
        sourceVertices,
        index,
        cartesianScratch
      );
      var height = sourceEncoding.decodeHeight(sourceVertices, index);

      var normal;
      if (sourceEncoding.hasVertexNormals) {
        normal = sourceEncoding.getOctEncodedNormal(
          sourceVertices,
          index,
          octEncodedNormalScratch
        );
      } else {
        normal = octEncodedNormalScratch;
        normal.x = 0.0;
        normal.y = 0.0;
      }

      var webMercatorT = v;
      if (sourceEncoding.hasWebMercatorT) {
        var latitude = CesiumMath.lerp(
          targetRectangle.south,
          targetRectangle.north,
          v
        );
        webMercatorT =
          (WebMercatorProjection.geodeticLatitudeToMercatorAngle(latitude) -
            southMercatorY) *
          oneOverMercatorHeight;
      }

      encoding.encode(
        typedArray,
        nextIndex * targetStride,
        position,
        uv,
        height,
        normal,
        webMercatorT
      );

      heightRange.minimumHeight = Math.min(heightRange.minimumHeight, height);
      heightRange.maximumHeight = Math.max(heightRange.maximumHeight, height);

      ++nextIndex;
    }

    return nextIndex;
  }

  function getNearestHeightOnEdge(meshes, tiles, isNext, edge, u, v) {
    var meshStart;
    var meshEnd;
    var meshStep;

    if (isNext) {
      meshStart = 0;
      meshEnd = meshes.length;
      meshStep = 1;
    } else {
      meshStart = meshes.length - 1;
      meshEnd = -1;
      meshStep = -1;
    }

    for (
      var meshIndex = meshStart;
      meshIndex !== meshEnd;
      meshIndex += meshStep
    ) {
      var mesh = meshes[meshIndex];
      var tile = tiles[meshIndex];
      if (!meshIsUsable(tile, mesh)) {
        continue;
      }

      var indices;
      switch (edge) {
        case TileEdge.WEST:
          indices = mesh.westIndicesSouthToNorth;
          break;
        case TileEdge.SOUTH:
          indices = mesh.southIndicesEastToWest;
          break;
        case TileEdge.EAST:
          indices = mesh.eastIndicesNorthToSouth;
          break;
        case TileEdge.NORTH:
          indices = mesh.northIndicesWestToEast;
          break;
      }

      var index = indices[isNext ? 0 : indices.length - 1];
      if (defined(index)) {
        return mesh.encoding.decodeHeight(mesh.vertices, index);
      }
    }

    return undefined;
  }

  function meshIsUsable(tile, mesh) {
    return (
      defined(mesh) &&
      (!defined(tile.data.fill) || !tile.data.fill.changedThisFrame)
    );
  }

  function getCornerFromEdge(
    terrainFillMesh,
    ellipsoid,
    edgeMeshes,
    edgeTiles,
    isNext,
    u,
    v,
    vertex
  ) {
    var edgeVertices;
    var compareU;
    var increasing;
    var vertexIndexIndex;
    var vertexIndex;
    var sourceTile = edgeTiles[isNext ? 0 : edgeMeshes.length - 1];
    var sourceMesh = edgeMeshes[isNext ? 0 : edgeMeshes.length - 1];

    if (meshIsUsable(sourceTile, sourceMesh)) {
      // Previous mesh is valid, but we don't know yet if it covers this corner.
      if (u === 0.0) {
        if (v === 0.0) {
          // southwest
          edgeVertices = isNext
            ? sourceMesh.northIndicesWestToEast
            : sourceMesh.eastIndicesNorthToSouth;
          compareU = isNext;
          increasing = isNext;
        } else {
          // northwest
          edgeVertices = isNext
            ? sourceMesh.eastIndicesNorthToSouth
            : sourceMesh.southIndicesEastToWest;
          compareU = !isNext;
          increasing = false;
        }
      } else if (v === 0.0) {
        // southeast
        edgeVertices = isNext
          ? sourceMesh.westIndicesSouthToNorth
          : sourceMesh.northIndicesWestToEast;
        compareU = !isNext;
        increasing = true;
      } else {
        // northeast
        edgeVertices = isNext
          ? sourceMesh.southIndicesEastToWest
          : sourceMesh.westIndicesSouthToNorth;
        compareU = isNext;
        increasing = !isNext;
      }

      if (edgeVertices.length > 0) {
        // The vertex we want will very often be the first/last vertex so check that first.
        vertexIndexIndex = isNext ? 0 : edgeVertices.length - 1;
        vertexIndex = edgeVertices[vertexIndexIndex];
        sourceMesh.encoding.decodeTextureCoordinates(
          sourceMesh.vertices,
          vertexIndex,
          uvScratch
        );
        var targetUv = transformTextureCoordinates(
          sourceTile,
          terrainFillMesh.tile,
          uvScratch,
          uvScratch
        );
        if (targetUv.x === u && targetUv.y === v) {
          // Vertex is good!
          getVertexFromTileAtCorner(sourceMesh, vertexIndex, u, v, vertex);
          return true;
        }

        // The last vertex is not the one we need, try binary searching for the right one.
        vertexIndexIndex = binarySearch(edgeVertices, compareU ? u : v, function (
          vertexIndex,
          textureCoordinate
        ) {
          sourceMesh.encoding.decodeTextureCoordinates(
            sourceMesh.vertices,
            vertexIndex,
            uvScratch
          );
          var targetUv = transformTextureCoordinates(
            sourceTile,
            terrainFillMesh.tile,
            uvScratch,
            uvScratch
          );
          if (increasing) {
            if (compareU) {
              return targetUv.x - u;
            }
            return targetUv.y - v;
          } else if (compareU) {
            return u - targetUv.x;
          }
          return v - targetUv.y;
        });

        if (vertexIndexIndex < 0) {
          vertexIndexIndex = ~vertexIndexIndex;

          if (vertexIndexIndex > 0 && vertexIndexIndex < edgeVertices.length) {
            // The corner falls between two vertices, so interpolate between them.
            getInterpolatedVertexAtCorner(
              ellipsoid,
              sourceTile,
              terrainFillMesh.tile,
              sourceMesh,
              edgeVertices[vertexIndexIndex - 1],
              edgeVertices[vertexIndexIndex],
              u,
              v,
              compareU,
              vertex
            );
            return true;
          }
        } else {
          // Found a vertex that fits in the corner exactly.
          getVertexFromTileAtCorner(
            sourceMesh,
            edgeVertices[vertexIndexIndex],
            u,
            v,
            vertex
          );
          return true;
        }
      }
    }

    return false;
  }

  var cornerPositionsScratch = [
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
  ];

  function computeOccludeePoint(
    tileProvider,
    center,
    rectangle,
    minimumHeight,
    maximumHeight,
    result
  ) {
    var ellipsoidalOccluder = tileProvider.quadtree._occluders.ellipsoid;
    var ellipsoid = ellipsoidalOccluder.ellipsoid;

    var cornerPositions = cornerPositionsScratch;
    Cartesian3.fromRadians(
      rectangle.west,
      rectangle.south,
      maximumHeight,
      ellipsoid,
      cornerPositions[0]
    );
    Cartesian3.fromRadians(
      rectangle.east,
      rectangle.south,
      maximumHeight,
      ellipsoid,
      cornerPositions[1]
    );
    Cartesian3.fromRadians(
      rectangle.west,
      rectangle.north,
      maximumHeight,
      ellipsoid,
      cornerPositions[2]
    );
    Cartesian3.fromRadians(
      rectangle.east,
      rectangle.north,
      maximumHeight,
      ellipsoid,
      cornerPositions[3]
    );

    return ellipsoidalOccluder.computeHorizonCullingPointPossiblyUnderEllipsoid(
      center,
      cornerPositions,
      minimumHeight,
      result
    );
  }

  /**
   * Provides quadtree tiles representing the surface of the globe.  This type is intended to be used
   * with {@link QuadtreePrimitive}.
   *
   * @alias GlobeSurfaceTileProvider
   * @constructor
   *
   * @param {TerrainProvider} options.terrainProvider The terrain provider that describes the surface geometry.
   * @param {ImageryLayerCollection} option.imageryLayers The collection of imagery layers describing the shading of the surface.
   * @param {GlobeSurfaceShaderSet} options.surfaceShaderSet The set of shaders used to render the surface.
   *
   * @private
   */
  function GlobeSurfaceTileProvider(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!defined(options.terrainProvider)) {
      throw new DeveloperError("options.terrainProvider is required.");
    } else if (!defined(options.imageryLayers)) {
      throw new DeveloperError("options.imageryLayers is required.");
    } else if (!defined(options.surfaceShaderSet)) {
      throw new DeveloperError("options.surfaceShaderSet is required.");
    }
    //>>includeEnd('debug');

    this.lightingFadeOutDistance = 6500000.0;
    this.lightingFadeInDistance = 9000000.0;
    this.hasWaterMask = false;
    this.oceanNormalMap = undefined;
    this.zoomedOutOceanSpecularIntensity = 0.5;
    this.enableLighting = false;
    this.dynamicAtmosphereLighting = false;
    this.dynamicAtmosphereLightingFromSun = false;
    this.showGroundAtmosphere = false;
    this.shadows = ShadowMode$1.RECEIVE_ONLY;

    /**
     * The color to use to highlight terrain fill tiles. If undefined, fill tiles are not
     * highlighted at all. The alpha value is used to alpha blend with the tile's
     * actual color. Because terrain fill tiles do not represent the actual terrain surface,
     * it may be useful in some applications to indicate visually that they are not to be trusted.
     * @type {Color}
     * @default undefined
     */
    this.fillHighlightColor = undefined;

    this.hueShift = 0.0;
    this.saturationShift = 0.0;
    this.brightnessShift = 0.0;

    this.showSkirts = true;
    this.backFaceCulling = true;
    this.undergroundColor = undefined;
    this.undergroundColorAlphaByDistance = undefined;

    this.materialUniformMap = undefined;
    this._materialUniformMap = undefined;

    this._quadtree = undefined;
    this._terrainProvider = options.terrainProvider;
    this._imageryLayers = options.imageryLayers;
    this._surfaceShaderSet = options.surfaceShaderSet;

    this._renderState = undefined;
    this._blendRenderState = undefined;
    this._disableCullingRenderState = undefined;
    this._disableCullingBlendRenderState = undefined;

    this._errorEvent = new Event();

    this._imageryLayers.layerAdded.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerAdded,
      this
    );
    this._imageryLayers.layerRemoved.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerRemoved,
      this
    );
    this._imageryLayers.layerMoved.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerMoved,
      this
    );
    this._imageryLayers.layerShownOrHidden.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerShownOrHidden,
      this
    );
    this._imageryLayersUpdatedEvent = new Event();

    this._layerOrderChanged = false;

    this._tilesToRenderByTextureCount = [];
    this._drawCommands = [];
    this._uniformMaps = [];
    this._usedDrawCommands = 0;

    this._vertexArraysToDestroy = [];

    this._debug = {
      wireframe: false,
      boundingSphereTile: undefined,
    };

    this._baseColor = undefined;
    this._firstPassInitialColor = undefined;
    this.baseColor = new Color(0.0, 0.0, 0.5, 1.0);

    /**
     * A property specifying a {@link ClippingPlaneCollection} used to selectively disable rendering on the outside of each plane.
     * @type {ClippingPlaneCollection}
     * @private
     */
    this._clippingPlanes = undefined;

    /**
     * A property specifying a {@link Rectangle} used to selectively limit terrain and imagery rendering.
     * @type {Rectangle}
     */
    this.cartographicLimitRectangle = Rectangle.clone(Rectangle.MAX_VALUE);

    this._hasLoadedTilesThisFrame = false;
    this._hasFillTilesThisFrame = false;
  }

  Object.defineProperties(GlobeSurfaceTileProvider.prototype, {
    /**
     * Gets or sets the color of the globe when no imagery is available.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {Color}
     */
    baseColor: {
      get: function () {
        return this._baseColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        this._baseColor = value;
        this._firstPassInitialColor = Cartesian4.fromColor(
          value,
          this._firstPassInitialColor
        );
      },
    },
    /**
     * Gets or sets the {@link QuadtreePrimitive} for which this provider is
     * providing tiles.  This property may be undefined if the provider is not yet associated
     * with a {@link QuadtreePrimitive}.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {QuadtreePrimitive}
     */
    quadtree: {
      get: function () {
        return this._quadtree;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        this._quadtree = value;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: function () {
        return (
          this._terrainProvider.ready &&
          (this._imageryLayers.length === 0 ||
            this._imageryLayers.get(0).imageryProvider.ready)
        );
      },
    },

    /**
     * Gets the tiling scheme used by the provider.  This property should
     * not be accessed before {@link GlobeSurfaceTileProvider#ready} returns true.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {TilingScheme}
     */
    tilingScheme: {
      get: function () {
        return this._terrainProvider.tilingScheme;
      },
    },

    /**
     * Gets an event that is raised when the geometry provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets an event that is raised when an imagery layer is added, shown, hidden, moved, or removed.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {Event}
     */
    imageryLayersUpdatedEvent: {
      get: function () {
        return this._imageryLayersUpdatedEvent;
      },
    },

    /**
     * Gets or sets the terrain provider that describes the surface geometry.
     * @memberof GlobeSurfaceTileProvider.prototype
     * @type {TerrainProvider}
     */
    terrainProvider: {
      get: function () {
        return this._terrainProvider;
      },
      set: function (terrainProvider) {
        if (this._terrainProvider === terrainProvider) {
          return;
        }

        //>>includeStart('debug', pragmas.debug);
        if (!defined(terrainProvider)) {
          throw new DeveloperError("terrainProvider is required.");
        }
        //>>includeEnd('debug');

        this._terrainProvider = terrainProvider;

        if (defined(this._quadtree)) {
          this._quadtree.invalidateAllTiles();
        }
      },
    },
    /**
     * The {@link ClippingPlaneCollection} used to selectively disable rendering the tileset.
     *
     * @type {ClippingPlaneCollection}
     *
     * @private
     */
    clippingPlanes: {
      get: function () {
        return this._clippingPlanes;
      },
      set: function (value) {
        ClippingPlaneCollection.setOwner(value, this, "_clippingPlanes");
      },
    },
  });

  function sortTileImageryByLayerIndex(a, b) {
    var aImagery = a.loadingImagery;
    if (!defined(aImagery)) {
      aImagery = a.readyImagery;
    }

    var bImagery = b.loadingImagery;
    if (!defined(bImagery)) {
      bImagery = b.readyImagery;
    }

    return aImagery.imageryLayer._layerIndex - bImagery.imageryLayer._layerIndex;
  }

  /**
   * Make updates to the tile provider that are not involved in rendering. Called before the render update cycle.
   */
  GlobeSurfaceTileProvider.prototype.update = function (frameState) {
    // update collection: imagery indices, base layers, raise layer show/hide event
    this._imageryLayers._update();
  };

  function updateCredits(surface, frameState) {
    var creditDisplay = frameState.creditDisplay;
    if (
      surface._terrainProvider.ready &&
      defined(surface._terrainProvider.credit)
    ) {
      creditDisplay.addCredit(surface._terrainProvider.credit);
    }

    var imageryLayers = surface._imageryLayers;
    for (var i = 0, len = imageryLayers.length; i < len; ++i) {
      var imageryProvider = imageryLayers.get(i).imageryProvider;
      if (imageryProvider.ready && defined(imageryProvider.credit)) {
        creditDisplay.addCredit(imageryProvider.credit);
      }
    }
  }

  /**
   * Called at the beginning of each render frame, before {@link QuadtreeTileProvider#showTileThisFrame}
   * @param {FrameState} frameState The frame state.
   */
  GlobeSurfaceTileProvider.prototype.initialize = function (frameState) {
    // update each layer for texture reprojection.
    this._imageryLayers.queueReprojectionCommands(frameState);

    if (this._layerOrderChanged) {
      this._layerOrderChanged = false;

      // Sort the TileImagery instances in each tile by the layer index.
      this._quadtree.forEachLoadedTile(function (tile) {
        tile.data.imagery.sort(sortTileImageryByLayerIndex);
      });
    }

    // Add credits for terrain and imagery providers.
    updateCredits(this, frameState);

    var vertexArraysToDestroy = this._vertexArraysToDestroy;
    var length = vertexArraysToDestroy.length;
    for (var j = 0; j < length; ++j) {
      GlobeSurfaceTile._freeVertexArray(vertexArraysToDestroy[j]);
    }
    vertexArraysToDestroy.length = 0;
  };

  /**
   * Called at the beginning of the update cycle for each render frame, before {@link QuadtreeTileProvider#showTileThisFrame}
   * or any other functions.
   *
   * @param {FrameState} frameState The frame state.
   */
  GlobeSurfaceTileProvider.prototype.beginUpdate = function (frameState) {
    var tilesToRenderByTextureCount = this._tilesToRenderByTextureCount;
    for (var i = 0, len = tilesToRenderByTextureCount.length; i < len; ++i) {
      var tiles = tilesToRenderByTextureCount[i];
      if (defined(tiles)) {
        tiles.length = 0;
      }
    }
    // update clipping planes
    var clippingPlanes = this._clippingPlanes;
    if (defined(clippingPlanes) && clippingPlanes.enabled) {
      clippingPlanes.update(frameState);
    }
    this._usedDrawCommands = 0;

    this._hasLoadedTilesThisFrame = false;
    this._hasFillTilesThisFrame = false;
  };

  /**
   * Called at the end of the update cycle for each render frame, after {@link QuadtreeTileProvider#showTileThisFrame}
   * and any other functions.
   *
   * @param {FrameState} frameState The frame state.
   */
  GlobeSurfaceTileProvider.prototype.endUpdate = function (frameState) {
    if (!defined(this._renderState)) {
      this._renderState = RenderState.fromCache({
        // Write color and depth
        cull: {
          enabled: true,
        },
        depthTest: {
          enabled: true,
          func: DepthFunction$1.LESS,
        },
      });

      this._blendRenderState = RenderState.fromCache({
        // Write color and depth
        cull: {
          enabled: true,
        },
        depthTest: {
          enabled: true,
          func: DepthFunction$1.LESS_OR_EQUAL,
        },
        blending: BlendingState$1.ALPHA_BLEND,
      });

      var rs = clone(this._renderState, true);
      rs.cull.enabled = false;
      this._disableCullingRenderState = RenderState.fromCache(rs);

      rs = clone(this._blendRenderState, true);
      rs.cull.enabled = false;
      this._disableCullingBlendRenderState = RenderState.fromCache(rs);
    }

    // If this frame has a mix of loaded and fill tiles, we need to propagate
    // loaded heights to the fill tiles.
    if (this._hasFillTilesThisFrame && this._hasLoadedTilesThisFrame) {
      TerrainFillMesh.updateFillTiles(
        this,
        this._quadtree._tilesToRender,
        frameState,
        this._vertexArraysToDestroy
      );
    }

    // Add the tile render commands to the command list, sorted by texture count.
    var tilesToRenderByTextureCount = this._tilesToRenderByTextureCount;
    for (
      var textureCountIndex = 0,
        textureCountLength = tilesToRenderByTextureCount.length;
      textureCountIndex < textureCountLength;
      ++textureCountIndex
    ) {
      var tilesToRender = tilesToRenderByTextureCount[textureCountIndex];
      if (!defined(tilesToRender)) {
        continue;
      }

      for (
        var tileIndex = 0, tileLength = tilesToRender.length;
        tileIndex < tileLength;
        ++tileIndex
      ) {
        var tile = tilesToRender[tileIndex];
        var tileBoundingRegion = tile.data.tileBoundingRegion;
        addDrawCommandsForTile(this, tile, frameState);
        frameState.minimumTerrainHeight = Math.min(
          frameState.minimumTerrainHeight,
          tileBoundingRegion.minimumHeight
        );
      }
    }
  };

  function pushCommand(command, frameState) {
    var globeTranslucencyState = frameState.globeTranslucencyState;
    if (globeTranslucencyState.translucent) {
      var isBlendCommand = command.renderState.blending.enabled;
      globeTranslucencyState.pushDerivedCommands(
        command,
        isBlendCommand,
        frameState
      );
    } else {
      frameState.commandList.push(command);
    }
  }

  /**
   * Adds draw commands for tiles rendered in the previous frame for a pick pass.
   *
   * @param {FrameState} frameState The frame state.
   */
  GlobeSurfaceTileProvider.prototype.updateForPick = function (frameState) {
    // Add the tile pick commands from the tiles drawn last frame.
    var drawCommands = this._drawCommands;
    for (var i = 0, length = this._usedDrawCommands; i < length; ++i) {
      pushCommand(drawCommands[i], frameState);
    }
  };

  /**
   * Cancels any imagery re-projections in the queue.
   */
  GlobeSurfaceTileProvider.prototype.cancelReprojections = function () {
    this._imageryLayers.cancelReprojections();
  };

  /**
   * Gets the maximum geometric error allowed in a tile at a given level, in meters.  This function should not be
   * called before {@link GlobeSurfaceTileProvider#ready} returns true.
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error in meters.
   */
  GlobeSurfaceTileProvider.prototype.getLevelMaximumGeometricError = function (
    level
  ) {
    return this._terrainProvider.getLevelMaximumGeometricError(level);
  };

  /**
   * Loads, or continues loading, a given tile.  This function will continue to be called
   * until {@link QuadtreeTile#state} is no longer {@link QuadtreeTileLoadState#LOADING}.  This function should
   * not be called before {@link GlobeSurfaceTileProvider#ready} returns true.
   *
   * @param {FrameState} frameState The frame state.
   * @param {QuadtreeTile} tile The tile to load.
   *
   * @exception {DeveloperError} <code>loadTile</code> must not be called before the tile provider is ready.
   */
  GlobeSurfaceTileProvider.prototype.loadTile = function (frameState, tile) {
    // We don't want to load imagery until we're certain that the terrain tiles are actually visible.
    // So if our bounding volume isn't accurate because it came from another tile, load terrain only
    // initially. If we load some terrain and suddenly have a more accurate bounding volume and the
    // tile is _still_ visible, give the tile a chance to load imagery immediately rather than
    // waiting for next frame.

    var surfaceTile = tile.data;
    var terrainOnly = true;
    var terrainStateBefore;
    if (defined(surfaceTile)) {
      terrainOnly =
        surfaceTile.boundingVolumeSourceTile !== tile ||
        tile._lastSelectionResult === TileSelectionResult.CULLED_BUT_NEEDED;
      terrainStateBefore = surfaceTile.terrainState;
    }

    GlobeSurfaceTile.processStateMachine(
      tile,
      frameState,
      this.terrainProvider,
      this._imageryLayers,
      this._vertexArraysToDestroy,
      terrainOnly
    );

    surfaceTile = tile.data;
    if (terrainOnly && terrainStateBefore !== tile.data.terrainState) {
      // Terrain state changed. If:
      // a) The tile is visible, and
      // b) The bounding volume is accurate (updated as a side effect of computing visibility)
      // Then we'll load imagery, too.
      if (
        this.computeTileVisibility(tile, frameState, this.quadtree.occluders) !==
          Visibility$1.NONE &&
        surfaceTile.boundingVolumeSourceTile === tile
      ) {
        terrainOnly = false;
        GlobeSurfaceTile.processStateMachine(
          tile,
          frameState,
          this.terrainProvider,
          this._imageryLayers,
          this._vertexArraysToDestroy,
          terrainOnly
        );
      }
    }
  };

  var boundingSphereScratch$1 = new BoundingSphere();
  var rectangleIntersectionScratch = new Rectangle();
  var splitCartographicLimitRectangleScratch = new Rectangle();
  var rectangleCenterScratch$3 = new Cartographic();

  // cartographicLimitRectangle may span the IDL, but tiles never will.
  function clipRectangleAntimeridian(tileRectangle, cartographicLimitRectangle) {
    if (cartographicLimitRectangle.west < cartographicLimitRectangle.east) {
      return cartographicLimitRectangle;
    }
    var splitRectangle = Rectangle.clone(
      cartographicLimitRectangle,
      splitCartographicLimitRectangleScratch
    );
    var tileCenter = Rectangle.center(tileRectangle, rectangleCenterScratch$3);
    if (tileCenter.longitude > 0.0) {
      splitRectangle.east = CesiumMath.PI;
    } else {
      splitRectangle.west = -CesiumMath.PI;
    }
    return splitRectangle;
  }

  function isUndergroundVisible(tileProvider, frameState) {
    if (frameState.cameraUnderground) {
      return true;
    }

    if (frameState.globeTranslucencyState.translucent) {
      return true;
    }

    if (tileProvider.backFaceCulling) {
      return false;
    }

    var clippingPlanes = tileProvider._clippingPlanes;
    if (defined(clippingPlanes) && clippingPlanes.enabled) {
      return true;
    }

    if (
      !Rectangle.equals(
        tileProvider.cartographicLimitRectangle,
        Rectangle.MAX_VALUE
      )
    ) {
      return true;
    }

    return false;
  }

  /**
   * Determines the visibility of a given tile.  The tile may be fully visible, partially visible, or not
   * visible at all.  Tiles that are renderable and are at least partially visible will be shown by a call
   * to {@link GlobeSurfaceTileProvider#showTileThisFrame}.
   *
   * @param {QuadtreeTile} tile The tile instance.
   * @param {FrameState} frameState The state information about the current frame.
   * @param {QuadtreeOccluders} occluders The objects that may occlude this tile.
   *
   * @returns {Visibility} Visibility.NONE if the tile is not visible,
   *                       Visibility.PARTIAL if the tile is partially visible, or
   *                       Visibility.FULL if the tile is fully visible.
   */
  GlobeSurfaceTileProvider.prototype.computeTileVisibility = function (
    tile,
    frameState,
    occluders
  ) {
    var distance = this.computeDistanceToTile(tile, frameState);
    tile._distance = distance;

    var undergroundVisible = isUndergroundVisible(this, frameState);

    if (frameState.fog.enabled && !undergroundVisible) {
      if (CesiumMath.fog(distance, frameState.fog.density) >= 1.0) {
        // Tile is completely in fog so return that it is not visible.
        return Visibility$1.NONE;
      }
    }

    var surfaceTile = tile.data;
    var tileBoundingRegion = surfaceTile.tileBoundingRegion;

    if (surfaceTile.boundingVolumeSourceTile === undefined) {
      // We have no idea where this tile is, so let's just call it partially visible.
      return Visibility$1.PARTIAL;
    }

    var cullingVolume = frameState.cullingVolume;
    var boundingVolume = surfaceTile.orientedBoundingBox;

    if (!defined(boundingVolume) && defined(surfaceTile.renderedMesh)) {
      boundingVolume = surfaceTile.renderedMesh.boundingSphere3D;
    }

    // Check if the tile is outside the limit area in cartographic space
    surfaceTile.clippedByBoundaries = false;
    var clippedCartographicLimitRectangle = clipRectangleAntimeridian(
      tile.rectangle,
      this.cartographicLimitRectangle
    );
    var areaLimitIntersection = Rectangle.simpleIntersection(
      clippedCartographicLimitRectangle,
      tile.rectangle,
      rectangleIntersectionScratch
    );
    if (!defined(areaLimitIntersection)) {
      return Visibility$1.NONE;
    }
    if (!Rectangle.equals(areaLimitIntersection, tile.rectangle)) {
      surfaceTile.clippedByBoundaries = true;
    }

    if (frameState.mode !== SceneMode$1.SCENE3D) {
      boundingVolume = boundingSphereScratch$1;
      BoundingSphere.fromRectangleWithHeights2D(
        tile.rectangle,
        frameState.mapProjection,
        tileBoundingRegion.minimumHeight,
        tileBoundingRegion.maximumHeight,
        boundingVolume
      );
      Cartesian3.fromElements(
        boundingVolume.center.z,
        boundingVolume.center.x,
        boundingVolume.center.y,
        boundingVolume.center
      );

      if (
        frameState.mode === SceneMode$1.MORPHING &&
        defined(surfaceTile.renderedMesh)
      ) {
        boundingVolume = BoundingSphere.union(
          surfaceTile.renderedMesh.boundingSphere3D,
          boundingVolume,
          boundingVolume
        );
      }
    }

    if (!defined(boundingVolume)) {
      return Visibility$1.PARTIAL;
    }

    var clippingPlanes = this._clippingPlanes;
    if (defined(clippingPlanes) && clippingPlanes.enabled) {
      var planeIntersection = clippingPlanes.computeIntersectionWithBoundingVolume(
        boundingVolume
      );
      tile.isClipped = planeIntersection !== Intersect$1.INSIDE;
      if (planeIntersection === Intersect$1.OUTSIDE) {
        return Visibility$1.NONE;
      }
    }

    var visibility;
    var intersection = cullingVolume.computeVisibility(boundingVolume);

    if (intersection === Intersect$1.OUTSIDE) {
      visibility = Visibility$1.NONE;
    } else if (intersection === Intersect$1.INTERSECTING) {
      visibility = Visibility$1.PARTIAL;
    } else if (intersection === Intersect$1.INSIDE) {
      visibility = Visibility$1.FULL;
    }

    if (visibility === Visibility$1.NONE) {
      return visibility;
    }

    var ortho3D =
      frameState.mode === SceneMode$1.SCENE3D &&
      frameState.camera.frustum instanceof OrthographicFrustum;
    if (
      frameState.mode === SceneMode$1.SCENE3D &&
      !ortho3D &&
      defined(occluders) &&
      !undergroundVisible
    ) {
      var occludeePointInScaledSpace = surfaceTile.occludeePointInScaledSpace;
      if (!defined(occludeePointInScaledSpace)) {
        return visibility;
      }

      if (
        occluders.ellipsoid.isScaledSpacePointVisiblePossiblyUnderEllipsoid(
          occludeePointInScaledSpace,
          tileBoundingRegion.minimumHeight
        )
      ) {
        return visibility;
      }

      return Visibility$1.NONE;
    }

    return visibility;
  };

  /**
   * Determines if the given tile can be refined
   * @param {QuadtreeTile} tile The tile to check.
   * @returns {boolean} True if the tile can be refined, false if it cannot.
   */
  GlobeSurfaceTileProvider.prototype.canRefine = function (tile) {
    // Only allow refinement it we know whether or not the children of this tile exist.
    // For a tileset with `availability`, we'll always be able to refine.
    // We can ask for availability of _any_ child tile because we only need to confirm
    // that we get a yes or no answer, it doesn't matter what the answer is.
    if (defined(tile.data.terrainData)) {
      return true;
    }
    var childAvailable = this.terrainProvider.getTileDataAvailable(
      tile.x * 2,
      tile.y * 2,
      tile.level + 1
    );
    return childAvailable !== undefined;
  };

  var readyImageryScratch = [];
  var canRenderTraversalStack = [];

  /**
   * Determines if the given not-fully-loaded tile can be rendered without losing detail that
   * was present last frame as a result of rendering descendant tiles. This method will only be
   * called if this tile's descendants were rendered last frame. If the tile is fully loaded,
   * it is assumed that this method will return true and it will not be called.
   * @param {QuadtreeTile} tile The tile to check.
   * @returns {boolean} True if the tile can be rendered without losing detail.
   */
  GlobeSurfaceTileProvider.prototype.canRenderWithoutLosingDetail = function (
    tile,
    frameState
  ) {
    var surfaceTile = tile.data;

    var readyImagery = readyImageryScratch;
    readyImagery.length = this._imageryLayers.length;

    var terrainReady = false;
    var initialImageryState = false;
    var imagery;

    if (defined(surfaceTile)) {
      // We can render even with non-ready terrain as long as all our rendered descendants
      // are missing terrain geometry too. i.e. if we rendered fills for more detailed tiles
      // last frame, it's ok to render a fill for this tile this frame.
      terrainReady = surfaceTile.terrainState === TerrainState$2.READY;

      // Initially assume all imagery layers are ready, unless imagery hasn't been initialized at all.
      initialImageryState = true;

      imagery = surfaceTile.imagery;
    }

    var i;
    var len;

    for (i = 0, len = readyImagery.length; i < len; ++i) {
      readyImagery[i] = initialImageryState;
    }

    if (defined(imagery)) {
      for (i = 0, len = imagery.length; i < len; ++i) {
        var tileImagery = imagery[i];
        var loadingImagery = tileImagery.loadingImagery;
        var isReady =
          !defined(loadingImagery) ||
          loadingImagery.state === ImageryState$1.FAILED ||
          loadingImagery.state === ImageryState$1.INVALID;
        var layerIndex = (tileImagery.loadingImagery || tileImagery.readyImagery)
          .imageryLayer._layerIndex;

        // For a layer to be ready, all tiles belonging to that layer must be ready.
        readyImagery[layerIndex] = isReady && readyImagery[layerIndex];
      }
    }

    var lastFrame = this.quadtree._lastSelectionFrameNumber;

    // Traverse the descendants looking for one with terrain or imagery that is not loaded on this tile.
    var stack = canRenderTraversalStack;
    stack.length = 0;
    stack.push(
      tile.southwestChild,
      tile.southeastChild,
      tile.northwestChild,
      tile.northeastChild
    );

    while (stack.length > 0) {
      var descendant = stack.pop();
      var lastFrameSelectionResult =
        descendant._lastSelectionResultFrame === lastFrame
          ? descendant._lastSelectionResult
          : TileSelectionResult.NONE;

      if (lastFrameSelectionResult === TileSelectionResult.RENDERED) {
        var descendantSurface = descendant.data;

        if (!defined(descendantSurface)) {
          // Descendant has no data, so it can't block rendering.
          continue;
        }

        if (
          !terrainReady &&
          descendant.data.terrainState === TerrainState$2.READY
        ) {
          // Rendered descendant has real terrain, but we don't. Rendering is blocked.
          return false;
        }

        var descendantImagery = descendant.data.imagery;
        for (i = 0, len = descendantImagery.length; i < len; ++i) {
          var descendantTileImagery = descendantImagery[i];
          var descendantLoadingImagery = descendantTileImagery.loadingImagery;
          var descendantIsReady =
            !defined(descendantLoadingImagery) ||
            descendantLoadingImagery.state === ImageryState$1.FAILED ||
            descendantLoadingImagery.state === ImageryState$1.INVALID;
          var descendantLayerIndex = (
            descendantTileImagery.loadingImagery ||
            descendantTileImagery.readyImagery
          ).imageryLayer._layerIndex;

          // If this imagery tile of a descendant is ready but the layer isn't ready in this tile,
          // then rendering is blocked.
          if (descendantIsReady && !readyImagery[descendantLayerIndex]) {
            return false;
          }
        }
      } else if (lastFrameSelectionResult === TileSelectionResult.REFINED) {
        stack.push(
          descendant.southwestChild,
          descendant.southeastChild,
          descendant.northwestChild,
          descendant.northeastChild
        );
      }
    }

    return true;
  };

  var tileDirectionScratch = new Cartesian3();

  /**
   * Determines the priority for loading this tile. Lower priority values load sooner.
   * @param {QuadtreeTile} tile The tile.
   * @param {FrameState} frameState The frame state.
   * @returns {Number} The load priority value.
   */
  GlobeSurfaceTileProvider.prototype.computeTileLoadPriority = function (
    tile,
    frameState
  ) {
    var surfaceTile = tile.data;
    if (surfaceTile === undefined) {
      return 0.0;
    }

    var obb = surfaceTile.orientedBoundingBox;
    if (obb === undefined) {
      return 0.0;
    }

    var cameraPosition = frameState.camera.positionWC;
    var cameraDirection = frameState.camera.directionWC;
    var tileDirection = Cartesian3.subtract(
      obb.center,
      cameraPosition,
      tileDirectionScratch
    );
    var magnitude = Cartesian3.magnitude(tileDirection);
    if (magnitude < CesiumMath.EPSILON5) {
      return 0.0;
    }
    Cartesian3.divideByScalar(tileDirection, magnitude, tileDirection);
    return (
      (1.0 - Cartesian3.dot(tileDirection, cameraDirection)) * tile._distance
    );
  };

  var modifiedModelViewScratch$3 = new Matrix4();
  var modifiedModelViewProjectionScratch = new Matrix4();
  var tileRectangleScratch = new Cartesian4();
  var localizedCartographicLimitRectangleScratch = new Cartesian4();
  var localizedTranslucencyRectangleScratch = new Cartesian4();
  var rtcScratch$3 = new Cartesian3();
  var centerEyeScratch = new Cartesian3();
  var southwestScratch = new Cartesian3();
  var northeastScratch = new Cartesian3();

  /**
   * Shows a specified tile in this frame.  The provider can cause the tile to be shown by adding
   * render commands to the commandList, or use any other method as appropriate.  The tile is not
   * expected to be visible next frame as well, unless this method is called next frame, too.
   *
   * @param {QuadtreeTile} tile The tile instance.
   * @param {FrameState} frameState The state information of the current rendering frame.
   */
  GlobeSurfaceTileProvider.prototype.showTileThisFrame = function (
    tile,
    frameState
  ) {
    var readyTextureCount = 0;
    var tileImageryCollection = tile.data.imagery;
    for (var i = 0, len = tileImageryCollection.length; i < len; ++i) {
      var tileImagery = tileImageryCollection[i];
      if (
        defined(tileImagery.readyImagery) &&
        tileImagery.readyImagery.imageryLayer.alpha !== 0.0
      ) {
        ++readyTextureCount;
      }
    }

    var tileSet = this._tilesToRenderByTextureCount[readyTextureCount];
    if (!defined(tileSet)) {
      tileSet = [];
      this._tilesToRenderByTextureCount[readyTextureCount] = tileSet;
    }

    tileSet.push(tile);

    var surfaceTile = tile.data;
    if (!defined(surfaceTile.vertexArray)) {
      this._hasFillTilesThisFrame = true;
    } else {
      this._hasLoadedTilesThisFrame = true;
    }

    var debug = this._debug;
    ++debug.tilesRendered;
    debug.texturesRendered += readyTextureCount;
  };

  var cornerPositionsScratch$1 = [
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
    new Cartesian3(),
  ];

  function computeOccludeePoint$1(
    tileProvider,
    center,
    rectangle,
    minimumHeight,
    maximumHeight,
    result
  ) {
    var ellipsoidalOccluder = tileProvider.quadtree._occluders.ellipsoid;
    var ellipsoid = ellipsoidalOccluder.ellipsoid;

    var cornerPositions = cornerPositionsScratch$1;
    Cartesian3.fromRadians(
      rectangle.west,
      rectangle.south,
      maximumHeight,
      ellipsoid,
      cornerPositions[0]
    );
    Cartesian3.fromRadians(
      rectangle.east,
      rectangle.south,
      maximumHeight,
      ellipsoid,
      cornerPositions[1]
    );
    Cartesian3.fromRadians(
      rectangle.west,
      rectangle.north,
      maximumHeight,
      ellipsoid,
      cornerPositions[2]
    );
    Cartesian3.fromRadians(
      rectangle.east,
      rectangle.north,
      maximumHeight,
      ellipsoid,
      cornerPositions[3]
    );

    return ellipsoidalOccluder.computeHorizonCullingPointPossiblyUnderEllipsoid(
      center,
      cornerPositions,
      minimumHeight,
      result
    );
  }

  /**
   * Gets the distance from the camera to the closest point on the tile.  This is used for level-of-detail selection.
   *
   * @param {QuadtreeTile} tile The tile instance.
   * @param {FrameState} frameState The state information of the current rendering frame.
   *
   * @returns {Number} The distance from the camera to the closest point on the tile, in meters.
   */
  GlobeSurfaceTileProvider.prototype.computeDistanceToTile = function (
    tile,
    frameState
  ) {
    // The distance should be:
    // 1. the actual distance to the tight-fitting bounding volume, or
    // 2. a distance that is equal to or greater than the actual distance to the tight-fitting bounding volume.
    //
    // When we don't know the min/max heights for a tile, but we do know the min/max of an ancestor tile, we can
    // build a tight-fitting bounding volume horizontally, but not vertically. The min/max heights from the
    // ancestor will likely form a volume that is much bigger than it needs to be. This means that the volume may
    // be deemed to be much closer to the camera than it really is, causing us to select tiles that are too detailed.
    // Loading too-detailed tiles is super expensive, so we don't want to do that. We don't know where the child
    // tile really lies within the parent range of heights, but we _do_ know the child tile can't be any closer than
    // the ancestor height surface (min or max) that is _farthest away_ from the camera. So if we compute distance
    // based that conservative metric, we may end up loading tiles that are not detailed enough, but that's much
    // better (faster) than loading tiles that are too detailed.

    var heightSource = updateTileBoundingRegion(
      tile,
      this.terrainProvider,
      frameState
    );
    var surfaceTile = tile.data;
    var tileBoundingRegion = surfaceTile.tileBoundingRegion;

    if (heightSource === undefined) {
      // Can't find any min/max heights anywhere? Ok, let's just say the
      // tile is really far away so we'll load and render it rather than
      // refining.
      return 9999999999.0;
    } else if (surfaceTile.boundingVolumeSourceTile !== heightSource) {
      // Heights are from a new source tile, so update the bounding volume.
      surfaceTile.boundingVolumeSourceTile = heightSource;

      var rectangle = tile.rectangle;
      if (defined(rectangle)) {
        surfaceTile.orientedBoundingBox = OrientedBoundingBox.fromRectangle(
          tile.rectangle,
          tileBoundingRegion.minimumHeight,
          tileBoundingRegion.maximumHeight,
          tile.tilingScheme.ellipsoid,
          surfaceTile.orientedBoundingBox
        );

        surfaceTile.occludeePointInScaledSpace = computeOccludeePoint$1(
          this,
          surfaceTile.orientedBoundingBox.center,
          tile.rectangle,
          tileBoundingRegion.minimumHeight,
          tileBoundingRegion.maximumHeight,
          surfaceTile.occludeePointInScaledSpace
        );
      }
    }

    var min = tileBoundingRegion.minimumHeight;
    var max = tileBoundingRegion.maximumHeight;

    if (surfaceTile.boundingVolumeSourceTile !== tile) {
      var cameraHeight = frameState.camera.positionCartographic.height;
      var distanceToMin = Math.abs(cameraHeight - min);
      var distanceToMax = Math.abs(cameraHeight - max);
      if (distanceToMin > distanceToMax) {
        tileBoundingRegion.minimumHeight = min;
        tileBoundingRegion.maximumHeight = min;
      } else {
        tileBoundingRegion.minimumHeight = max;
        tileBoundingRegion.maximumHeight = max;
      }
    }

    var result = tileBoundingRegion.distanceToCamera(frameState);

    tileBoundingRegion.minimumHeight = min;
    tileBoundingRegion.maximumHeight = max;

    return result;
  };

  function updateTileBoundingRegion(tile, terrainProvider, frameState) {
    var surfaceTile = tile.data;
    if (surfaceTile === undefined) {
      surfaceTile = tile.data = new GlobeSurfaceTile();
    }

    if (surfaceTile.tileBoundingRegion === undefined) {
      surfaceTile.tileBoundingRegion = new TileBoundingRegion({
        computeBoundingVolumes: false,
        rectangle: tile.rectangle,
        ellipsoid: tile.tilingScheme.ellipsoid,
        minimumHeight: 0.0,
        maximumHeight: 0.0,
      });
    }

    var terrainData = surfaceTile.terrainData;
    var mesh = surfaceTile.mesh;
    var tileBoundingRegion = surfaceTile.tileBoundingRegion;

    if (
      mesh !== undefined &&
      mesh.minimumHeight !== undefined &&
      mesh.maximumHeight !== undefined
    ) {
      // We have tight-fitting min/max heights from the mesh.
      tileBoundingRegion.minimumHeight = mesh.minimumHeight;
      tileBoundingRegion.maximumHeight = mesh.maximumHeight;
      return tile;
    }

    if (
      terrainData !== undefined &&
      terrainData._minimumHeight !== undefined &&
      terrainData._maximumHeight !== undefined
    ) {
      // We have tight-fitting min/max heights from the terrain data.
      tileBoundingRegion.minimumHeight =
        terrainData._minimumHeight * frameState.terrainExaggeration;
      tileBoundingRegion.maximumHeight =
        terrainData._maximumHeight * frameState.terrainExaggeration;
      return tile;
    }

    // No accurate min/max heights available, so we're stuck with min/max heights from an ancestor tile.
    tileBoundingRegion.minimumHeight = Number.NaN;
    tileBoundingRegion.maximumHeight = Number.NaN;

    var ancestor = tile.parent;
    while (ancestor !== undefined) {
      var ancestorSurfaceTile = ancestor.data;
      if (ancestorSurfaceTile !== undefined) {
        var ancestorMesh = ancestorSurfaceTile.mesh;
        if (
          ancestorMesh !== undefined &&
          ancestorMesh.minimumHeight !== undefined &&
          ancestorMesh.maximumHeight !== undefined
        ) {
          tileBoundingRegion.minimumHeight = ancestorMesh.minimumHeight;
          tileBoundingRegion.maximumHeight = ancestorMesh.maximumHeight;
          return ancestor;
        }

        var ancestorTerrainData = ancestorSurfaceTile.terrainData;
        if (
          ancestorTerrainData !== undefined &&
          ancestorTerrainData._minimumHeight !== undefined &&
          ancestorTerrainData._maximumHeight !== undefined
        ) {
          tileBoundingRegion.minimumHeight =
            ancestorTerrainData._minimumHeight * frameState.terrainExaggeration;
          tileBoundingRegion.maximumHeight =
            ancestorTerrainData._maximumHeight * frameState.terrainExaggeration;
          return ancestor;
        }
      }
      ancestor = ancestor.parent;
    }

    return undefined;
  }

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see GlobeSurfaceTileProvider#destroy
   */
  GlobeSurfaceTileProvider.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * provider = provider && provider();
   *
   * @see GlobeSurfaceTileProvider#isDestroyed
   */
  GlobeSurfaceTileProvider.prototype.destroy = function () {
    this._tileProvider = this._tileProvider && this._tileProvider.destroy();
    this._clippingPlanes = this._clippingPlanes && this._clippingPlanes.destroy();

    return destroyObject(this);
  };

  function getTileReadyCallback(tileImageriesToFree, layer, terrainProvider) {
    return function (tile) {
      var tileImagery;
      var imagery;
      var startIndex = -1;
      var tileImageryCollection = tile.data.imagery;
      var length = tileImageryCollection.length;
      var i;
      for (i = 0; i < length; ++i) {
        tileImagery = tileImageryCollection[i];
        imagery = defaultValue(
          tileImagery.readyImagery,
          tileImagery.loadingImagery
        );
        if (imagery.imageryLayer === layer) {
          startIndex = i;
          break;
        }
      }

      if (startIndex !== -1) {
        var endIndex = startIndex + tileImageriesToFree;
        tileImagery = tileImageryCollection[endIndex];
        imagery = defined(tileImagery)
          ? defaultValue(tileImagery.readyImagery, tileImagery.loadingImagery)
          : undefined;
        if (!defined(imagery) || imagery.imageryLayer !== layer) {
          // Return false to keep the callback if we have to wait on the skeletons
          // Return true to remove the callback if something went wrong
          return !layer._createTileImagerySkeletons(
            tile,
            terrainProvider,
            endIndex
          );
        }

        for (i = startIndex; i < endIndex; ++i) {
          tileImageryCollection[i].freeResources();
        }

        tileImageryCollection.splice(startIndex, tileImageriesToFree);
      }

      return true; // Everything is done, so remove the callback
    };
  }

  GlobeSurfaceTileProvider.prototype._onLayerAdded = function (layer, index) {
    if (layer.show) {
      var terrainProvider = this._terrainProvider;

      var that = this;
      var imageryProvider = layer.imageryProvider;
      var tileImageryUpdatedEvent = this._imageryLayersUpdatedEvent;
      imageryProvider._reload = function () {
        // Clear the layer's cache
        layer._imageryCache = {};

        that._quadtree.forEachLoadedTile(function (tile) {
          // If this layer is still waiting to for the loaded callback, just return
          if (defined(tile._loadedCallbacks[layer._layerIndex])) {
            return;
          }

          var i;

          // Figure out how many TileImageries we will need to remove and where to insert new ones
          var tileImageryCollection = tile.data.imagery;
          var length = tileImageryCollection.length;
          var startIndex = -1;
          var tileImageriesToFree = 0;
          for (i = 0; i < length; ++i) {
            var tileImagery = tileImageryCollection[i];
            var imagery = defaultValue(
              tileImagery.readyImagery,
              tileImagery.loadingImagery
            );
            if (imagery.imageryLayer === layer) {
              if (startIndex === -1) {
                startIndex = i;
              }

              ++tileImageriesToFree;
            } else if (startIndex !== -1) {
              // iterated past the section of TileImageries belonging to this layer, no need to continue.
              break;
            }
          }

          if (startIndex === -1) {
            return;
          }

          // Insert immediately after existing TileImageries
          var insertionPoint = startIndex + tileImageriesToFree;

          // Create new TileImageries for all loaded tiles
          if (
            layer._createTileImagerySkeletons(
              tile,
              terrainProvider,
              insertionPoint
            )
          ) {
            // Add callback to remove old TileImageries when the new TileImageries are ready
            tile._loadedCallbacks[layer._layerIndex] = getTileReadyCallback(
              tileImageriesToFree,
              layer,
              terrainProvider
            );

            tile.state = QuadtreeTileLoadState$1.LOADING;
          }
        });
      };

      // create TileImageries for this layer for all previously loaded tiles
      this._quadtree.forEachLoadedTile(function (tile) {
        if (layer._createTileImagerySkeletons(tile, terrainProvider)) {
          tile.state = QuadtreeTileLoadState$1.LOADING;

          // Tiles that are not currently being rendered need to load the new layer before they're renderable.
          // We don't mark the rendered tiles non-renderable, though, because that would make the globe disappear.
          if (
            tile.level !== 0 &&
            (tile._lastSelectionResultFrame !==
              that.quadtree._lastSelectionFrameNumber ||
              tile._lastSelectionResult !== TileSelectionResult.RENDERED)
          ) {
            tile.renderable = false;
          }
        }
      });

      this._layerOrderChanged = true;
      tileImageryUpdatedEvent.raiseEvent();
    }
  };

  GlobeSurfaceTileProvider.prototype._onLayerRemoved = function (layer, index) {
    // destroy TileImagerys for this layer for all previously loaded tiles
    this._quadtree.forEachLoadedTile(function (tile) {
      var tileImageryCollection = tile.data.imagery;

      var startIndex = -1;
      var numDestroyed = 0;
      for (var i = 0, len = tileImageryCollection.length; i < len; ++i) {
        var tileImagery = tileImageryCollection[i];
        var imagery = tileImagery.loadingImagery;
        if (!defined(imagery)) {
          imagery = tileImagery.readyImagery;
        }
        if (imagery.imageryLayer === layer) {
          if (startIndex === -1) {
            startIndex = i;
          }

          tileImagery.freeResources();
          ++numDestroyed;
        } else if (startIndex !== -1) {
          // iterated past the section of TileImagerys belonging to this layer, no need to continue.
          break;
        }
      }

      if (startIndex !== -1) {
        tileImageryCollection.splice(startIndex, numDestroyed);
      }
    });

    if (defined(layer.imageryProvider)) {
      layer.imageryProvider._reload = undefined;
    }

    this._imageryLayersUpdatedEvent.raiseEvent();
  };

  GlobeSurfaceTileProvider.prototype._onLayerMoved = function (
    layer,
    newIndex,
    oldIndex
  ) {
    this._layerOrderChanged = true;
    this._imageryLayersUpdatedEvent.raiseEvent();
  };

  GlobeSurfaceTileProvider.prototype._onLayerShownOrHidden = function (
    layer,
    index,
    show
  ) {
    if (show) {
      this._onLayerAdded(layer, index);
    } else {
      this._onLayerRemoved(layer, index);
    }
  };

  var scratchClippingPlaneMatrix$2 = new Matrix4();
  function createTileUniformMap(frameState, globeSurfaceTileProvider) {
    var uniformMap = {
      u_initialColor: function () {
        return this.properties.initialColor;
      },
      u_fillHighlightColor: function () {
        return this.properties.fillHighlightColor;
      },
      u_zoomedOutOceanSpecularIntensity: function () {
        return this.properties.zoomedOutOceanSpecularIntensity;
      },
      u_oceanNormalMap: function () {
        return this.properties.oceanNormalMap;
      },
      u_lightingFadeDistance: function () {
        return this.properties.lightingFadeDistance;
      },
      u_nightFadeDistance: function () {
        return this.properties.nightFadeDistance;
      },
      u_center3D: function () {
        return this.properties.center3D;
      },
      u_tileRectangle: function () {
        return this.properties.tileRectangle;
      },
      u_modifiedModelView: function () {
        var viewMatrix = frameState.context.uniformState.view;
        var centerEye = Matrix4.multiplyByPoint(
          viewMatrix,
          this.properties.rtc,
          centerEyeScratch
        );
        Matrix4.setTranslation(viewMatrix, centerEye, modifiedModelViewScratch$3);
        return modifiedModelViewScratch$3;
      },
      u_modifiedModelViewProjection: function () {
        var viewMatrix = frameState.context.uniformState.view;
        var projectionMatrix = frameState.context.uniformState.projection;
        var centerEye = Matrix4.multiplyByPoint(
          viewMatrix,
          this.properties.rtc,
          centerEyeScratch
        );
        Matrix4.setTranslation(
          viewMatrix,
          centerEye,
          modifiedModelViewProjectionScratch
        );
        Matrix4.multiply(
          projectionMatrix,
          modifiedModelViewProjectionScratch,
          modifiedModelViewProjectionScratch
        );
        return modifiedModelViewProjectionScratch;
      },
      u_dayTextures: function () {
        return this.properties.dayTextures;
      },
      u_dayTextureTranslationAndScale: function () {
        return this.properties.dayTextureTranslationAndScale;
      },
      u_dayTextureTexCoordsRectangle: function () {
        return this.properties.dayTextureTexCoordsRectangle;
      },
      u_dayTextureUseWebMercatorT: function () {
        return this.properties.dayTextureUseWebMercatorT;
      },
      u_dayTextureAlpha: function () {
        return this.properties.dayTextureAlpha;
      },
      u_dayTextureNightAlpha: function () {
        return this.properties.dayTextureNightAlpha;
      },
      u_dayTextureDayAlpha: function () {
        return this.properties.dayTextureDayAlpha;
      },
      u_dayTextureBrightness: function () {
        return this.properties.dayTextureBrightness;
      },
      u_dayTextureContrast: function () {
        return this.properties.dayTextureContrast;
      },
      u_dayTextureHue: function () {
        return this.properties.dayTextureHue;
      },
      u_dayTextureSaturation: function () {
        return this.properties.dayTextureSaturation;
      },
      u_dayTextureOneOverGamma: function () {
        return this.properties.dayTextureOneOverGamma;
      },
      u_dayIntensity: function () {
        return this.properties.dayIntensity;
      },
      u_southAndNorthLatitude: function () {
        return this.properties.southAndNorthLatitude;
      },
      u_southMercatorYAndOneOverHeight: function () {
        return this.properties.southMercatorYAndOneOverHeight;
      },
      u_waterMask: function () {
        return this.properties.waterMask;
      },
      u_waterMaskTranslationAndScale: function () {
        return this.properties.waterMaskTranslationAndScale;
      },
      u_minMaxHeight: function () {
        return this.properties.minMaxHeight;
      },
      u_scaleAndBias: function () {
        return this.properties.scaleAndBias;
      },
      u_dayTextureSplit: function () {
        return this.properties.dayTextureSplit;
      },
      u_dayTextureCutoutRectangles: function () {
        return this.properties.dayTextureCutoutRectangles;
      },
      u_clippingPlanes: function () {
        var clippingPlanes = globeSurfaceTileProvider._clippingPlanes;
        if (defined(clippingPlanes) && defined(clippingPlanes.texture)) {
          // Check in case clippingPlanes hasn't been updated yet.
          return clippingPlanes.texture;
        }
        return frameState.context.defaultTexture;
      },
      u_cartographicLimitRectangle: function () {
        return this.properties.localizedCartographicLimitRectangle;
      },
      u_clippingPlanesMatrix: function () {
        var clippingPlanes = globeSurfaceTileProvider._clippingPlanes;
        return defined(clippingPlanes)
          ? Matrix4.multiply(
              frameState.context.uniformState.view,
              clippingPlanes.modelMatrix,
              scratchClippingPlaneMatrix$2
            )
          : Matrix4.IDENTITY;
      },
      u_clippingPlanesEdgeStyle: function () {
        var style = this.properties.clippingPlanesEdgeColor;
        style.alpha = this.properties.clippingPlanesEdgeWidth;
        return style;
      },
      u_minimumBrightness: function () {
        return frameState.fog.minimumBrightness;
      },
      u_hsbShift: function () {
        return this.properties.hsbShift;
      },
      u_colorsToAlpha: function () {
        return this.properties.colorsToAlpha;
      },
      u_frontFaceAlphaByDistance: function () {
        return this.properties.frontFaceAlphaByDistance;
      },
      u_backFaceAlphaByDistance: function () {
        return this.properties.backFaceAlphaByDistance;
      },
      u_translucencyRectangle: function () {
        return this.properties.localizedTranslucencyRectangle;
      },
      u_undergroundColor: function () {
        return this.properties.undergroundColor;
      },
      u_undergroundColorAlphaByDistance: function () {
        return this.properties.undergroundColorAlphaByDistance;
      },

      // make a separate object so that changes to the properties are seen on
      // derived commands that combine another uniform map with this one.
      properties: {
        initialColor: new Cartesian4(0.0, 0.0, 0.5, 1.0),
        fillHighlightColor: new Color(0.0, 0.0, 0.0, 0.0),
        zoomedOutOceanSpecularIntensity: 0.5,
        oceanNormalMap: undefined,
        lightingFadeDistance: new Cartesian2(6500000.0, 9000000.0),
        nightFadeDistance: new Cartesian2(10000000.0, 40000000.0),
        hsbShift: new Cartesian3(),

        center3D: undefined,
        rtc: new Cartesian3(),
        modifiedModelView: new Matrix4(),
        tileRectangle: new Cartesian4(),

        dayTextures: [],
        dayTextureTranslationAndScale: [],
        dayTextureTexCoordsRectangle: [],
        dayTextureUseWebMercatorT: [],
        dayTextureAlpha: [],
        dayTextureNightAlpha: [],
        dayTextureDayAlpha: [],
        dayTextureBrightness: [],
        dayTextureContrast: [],
        dayTextureHue: [],
        dayTextureSaturation: [],
        dayTextureOneOverGamma: [],
        dayTextureSplit: [],
        dayTextureCutoutRectangles: [],
        dayIntensity: 0.0,
        colorsToAlpha: [],

        southAndNorthLatitude: new Cartesian2(),
        southMercatorYAndOneOverHeight: new Cartesian2(),

        waterMask: undefined,
        waterMaskTranslationAndScale: new Cartesian4(),

        minMaxHeight: new Cartesian2(),
        scaleAndBias: new Matrix4(),
        clippingPlanesEdgeColor: Color.clone(Color.WHITE),
        clippingPlanesEdgeWidth: 0.0,

        localizedCartographicLimitRectangle: new Cartesian4(),

        frontFaceAlphaByDistance: new Cartesian4(),
        backFaceAlphaByDistance: new Cartesian4(),
        localizedTranslucencyRectangle: new Cartesian4(),
        undergroundColor: Color.clone(Color.TRANSPARENT),
        undergroundColorAlphaByDistance: new Cartesian4(),
      },
    };

    if (defined(globeSurfaceTileProvider.materialUniformMap)) {
      return combine(uniformMap, globeSurfaceTileProvider.materialUniformMap);
    }

    return uniformMap;
  }

  function createWireframeVertexArrayIfNecessary(context, provider, tile) {
    var surfaceTile = tile.data;

    var mesh;
    var vertexArray;

    if (defined(surfaceTile.vertexArray)) {
      mesh = surfaceTile.mesh;
      vertexArray = surfaceTile.vertexArray;
    } else if (
      defined(surfaceTile.fill) &&
      defined(surfaceTile.fill.vertexArray)
    ) {
      mesh = surfaceTile.fill.mesh;
      vertexArray = surfaceTile.fill.vertexArray;
    }

    if (!defined(mesh) || !defined(vertexArray)) {
      return;
    }

    if (defined(surfaceTile.wireframeVertexArray)) {
      if (surfaceTile.wireframeVertexArray.mesh === mesh) {
        return;
      }

      surfaceTile.wireframeVertexArray.destroy();
      surfaceTile.wireframeVertexArray = undefined;
    }

    surfaceTile.wireframeVertexArray = createWireframeVertexArray(
      context,
      vertexArray,
      mesh
    );
    surfaceTile.wireframeVertexArray.mesh = mesh;
  }

  /**
   * Creates a vertex array for wireframe rendering of a terrain tile.
   *
   * @private
   *
   * @param {Context} context The context in which to create the vertex array.
   * @param {VertexArray} vertexArray The existing, non-wireframe vertex array.  The new vertex array
   *                      will share vertex buffers with this existing one.
   * @param {TerrainMesh} terrainMesh The terrain mesh containing non-wireframe indices.
   * @returns {VertexArray} The vertex array for wireframe rendering.
   */
  function createWireframeVertexArray(context, vertexArray, terrainMesh) {
    var indices = terrainMesh.indices;

    var geometry = {
      indices: indices,
      primitiveType: PrimitiveType$1.TRIANGLES,
    };

    GeometryPipeline.toWireframe(geometry);

    var wireframeIndices = geometry.indices;
    var wireframeIndexBuffer = Buffer$1.createIndexBuffer({
      context: context,
      typedArray: wireframeIndices,
      usage: BufferUsage$1.STATIC_DRAW,
      indexDatatype: IndexDatatype$1.fromSizeInBytes(
        wireframeIndices.BYTES_PER_ELEMENT
      ),
    });
    return new VertexArray({
      context: context,
      attributes: vertexArray._attributes,
      indexBuffer: wireframeIndexBuffer,
    });
  }

  var getDebugOrientedBoundingBox;
  var getDebugBoundingSphere;
  var debugDestroyPrimitive;

  (function () {
    var instanceOBB = new GeometryInstance({
      geometry: BoxOutlineGeometry.fromDimensions({
        dimensions: new Cartesian3(2.0, 2.0, 2.0),
      }),
    });
    var instanceSphere = new GeometryInstance({
      geometry: new SphereOutlineGeometry({ radius: 1.0 }),
    });
    var modelMatrix = new Matrix4();
    var previousVolume;
    var primitive;

    function createDebugPrimitive(instance) {
      return new Primitive({
        geometryInstances: instance,
        appearance: new PerInstanceColorAppearance({
          translucent: false,
          flat: true,
        }),
        asynchronous: false,
      });
    }

    getDebugOrientedBoundingBox = function (obb, color) {
      if (obb === previousVolume) {
        return primitive;
      }
      debugDestroyPrimitive();

      previousVolume = obb;
      modelMatrix = Matrix4.fromRotationTranslation(
        obb.halfAxes,
        obb.center,
        modelMatrix
      );

      instanceOBB.modelMatrix = modelMatrix;
      instanceOBB.attributes.color = ColorGeometryInstanceAttribute.fromColor(
        color
      );

      primitive = createDebugPrimitive(instanceOBB);
      return primitive;
    };

    getDebugBoundingSphere = function (sphere, color) {
      if (sphere === previousVolume) {
        return primitive;
      }
      debugDestroyPrimitive();

      previousVolume = sphere;
      modelMatrix = Matrix4.fromTranslation(sphere.center, modelMatrix);
      modelMatrix = Matrix4.multiplyByUniformScale(
        modelMatrix,
        sphere.radius,
        modelMatrix
      );

      instanceSphere.modelMatrix = modelMatrix;
      instanceSphere.attributes.color = ColorGeometryInstanceAttribute.fromColor(
        color
      );

      primitive = createDebugPrimitive(instanceSphere);
      return primitive;
    };

    debugDestroyPrimitive = function () {
      if (defined(primitive)) {
        primitive.destroy();
        primitive = undefined;
        previousVolume = undefined;
      }
    };
  })();

  var otherPassesInitialColor = new Cartesian4(0.0, 0.0, 0.0, 0.0);
  var surfaceShaderSetOptionsScratch = {
    frameState: undefined,
    surfaceTile: undefined,
    numberOfDayTextures: undefined,
    applyBrightness: undefined,
    applyContrast: undefined,
    applyHue: undefined,
    applySaturation: undefined,
    applyGamma: undefined,
    applyAlpha: undefined,
    applyDayNightAlpha: undefined,
    applySplit: undefined,
    showReflectiveOcean: undefined,
    showOceanWaves: undefined,
    enableLighting: undefined,
    dynamicAtmosphereLighting: undefined,
    dynamicAtmosphereLightingFromSun: undefined,
    showGroundAtmosphere: undefined,
    perFragmentGroundAtmosphere: undefined,
    hasVertexNormals: undefined,
    useWebMercatorProjection: undefined,
    enableFog: undefined,
    enableClippingPlanes: undefined,
    clippingPlanes: undefined,
    clippedByBoundaries: undefined,
    hasImageryLayerCutout: undefined,
    colorCorrect: undefined,
    colorToAlpha: undefined,
  };

  var defaultUndergroundColor = Color.TRANSPARENT;
  var defaultundergroundColorAlphaByDistance = new NearFarScalar();

  function addDrawCommandsForTile(tileProvider, tile, frameState) {
    var surfaceTile = tile.data;

    if (!defined(surfaceTile.vertexArray)) {
      if (surfaceTile.fill === undefined) {
        // No fill was created for this tile, probably because this tile is not connected to
        // any renderable tiles. So create a simple tile in the middle of the tile's possible
        // height range.
        surfaceTile.fill = new TerrainFillMesh(tile);
      }
      surfaceTile.fill.update(tileProvider, frameState);
    }

    var creditDisplay = frameState.creditDisplay;

    var terrainData = surfaceTile.terrainData;
    if (defined(terrainData) && defined(terrainData.credits)) {
      var tileCredits = terrainData.credits;
      for (
        var tileCreditIndex = 0, tileCreditLength = tileCredits.length;
        tileCreditIndex < tileCreditLength;
        ++tileCreditIndex
      ) {
        creditDisplay.addCredit(tileCredits[tileCreditIndex]);
      }
    }

    var maxTextures = ContextLimits.maximumTextureImageUnits;

    var waterMaskTexture = surfaceTile.waterMaskTexture;
    var waterMaskTranslationAndScale = surfaceTile.waterMaskTranslationAndScale;
    if (!defined(waterMaskTexture) && defined(surfaceTile.fill)) {
      waterMaskTexture = surfaceTile.fill.waterMaskTexture;
      waterMaskTranslationAndScale =
        surfaceTile.fill.waterMaskTranslationAndScale;
    }

    var cameraUnderground = frameState.cameraUnderground;

    var globeTranslucencyState = frameState.globeTranslucencyState;
    var translucent = globeTranslucencyState.translucent;
    var frontFaceAlphaByDistance =
      globeTranslucencyState.frontFaceAlphaByDistance;
    var backFaceAlphaByDistance = globeTranslucencyState.backFaceAlphaByDistance;
    var translucencyRectangle = globeTranslucencyState.rectangle;

    var undergroundColor = defaultValue(
      tileProvider.undergroundColor,
      defaultUndergroundColor
    );
    var undergroundColorAlphaByDistance = defaultValue(
      tileProvider.undergroundColorAlphaByDistance,
      defaultundergroundColorAlphaByDistance
    );
    var showUndergroundColor =
      isUndergroundVisible(tileProvider, frameState) &&
      frameState.mode === SceneMode$1.SCENE3D &&
      undergroundColor.alpha > 0.0 &&
      (undergroundColorAlphaByDistance.nearValue > 0.0 ||
        undergroundColorAlphaByDistance.farValue > 0.0);

    var showReflectiveOcean =
      tileProvider.hasWaterMask && defined(waterMaskTexture);
    var oceanNormalMap = tileProvider.oceanNormalMap;
    var showOceanWaves = showReflectiveOcean && defined(oceanNormalMap);
    var hasVertexNormals =
      tileProvider.terrainProvider.ready &&
      tileProvider.terrainProvider.hasVertexNormals;
    var enableFog = frameState.fog.enabled && !cameraUnderground;
    var showGroundAtmosphere =
      tileProvider.showGroundAtmosphere && frameState.mode === SceneMode$1.SCENE3D;
    var castShadows =
      ShadowMode$1.castShadows(tileProvider.shadows) && !translucent;
    var receiveShadows =
      ShadowMode$1.receiveShadows(tileProvider.shadows) && !translucent;

    var hueShift = tileProvider.hueShift;
    var saturationShift = tileProvider.saturationShift;
    var brightnessShift = tileProvider.brightnessShift;

    var colorCorrect = !(
      CesiumMath.equalsEpsilon(hueShift, 0.0, CesiumMath.EPSILON7) &&
      CesiumMath.equalsEpsilon(saturationShift, 0.0, CesiumMath.EPSILON7) &&
      CesiumMath.equalsEpsilon(brightnessShift, 0.0, CesiumMath.EPSILON7)
    );

    var perFragmentGroundAtmosphere = false;
    if (showGroundAtmosphere) {
      var cameraDistance = Cartesian3.magnitude(frameState.camera.positionWC);
      var fadeOutDistance = tileProvider.nightFadeOutDistance;
      perFragmentGroundAtmosphere = cameraDistance > fadeOutDistance;
    }

    if (showReflectiveOcean) {
      --maxTextures;
    }
    if (showOceanWaves) {
      --maxTextures;
    }
    if (
      defined(frameState.shadowState) &&
      frameState.shadowState.shadowsEnabled
    ) {
      --maxTextures;
    }
    if (
      defined(tileProvider.clippingPlanes) &&
      tileProvider.clippingPlanes.enabled
    ) {
      --maxTextures;
    }

    maxTextures -= globeTranslucencyState.numberOfTextureUniforms;

    var mesh = surfaceTile.renderedMesh;
    var rtc = mesh.center;
    var encoding = mesh.encoding;

    // Not used in 3D.
    var tileRectangle = tileRectangleScratch;

    // Only used for Mercator projections.
    var southLatitude = 0.0;
    var northLatitude = 0.0;
    var southMercatorY = 0.0;
    var oneOverMercatorHeight = 0.0;

    var useWebMercatorProjection = false;

    if (frameState.mode !== SceneMode$1.SCENE3D) {
      var projection = frameState.mapProjection;
      var southwest = projection.project(
        Rectangle.southwest(tile.rectangle),
        southwestScratch
      );
      var northeast = projection.project(
        Rectangle.northeast(tile.rectangle),
        northeastScratch
      );

      tileRectangle.x = southwest.x;
      tileRectangle.y = southwest.y;
      tileRectangle.z = northeast.x;
      tileRectangle.w = northeast.y;

      // In 2D and Columbus View, use the center of the tile for RTC rendering.
      if (frameState.mode !== SceneMode$1.MORPHING) {
        rtc = rtcScratch$3;
        rtc.x = 0.0;
        rtc.y = (tileRectangle.z + tileRectangle.x) * 0.5;
        rtc.z = (tileRectangle.w + tileRectangle.y) * 0.5;
        tileRectangle.x -= rtc.y;
        tileRectangle.y -= rtc.z;
        tileRectangle.z -= rtc.y;
        tileRectangle.w -= rtc.z;
      }

      if (
        frameState.mode === SceneMode$1.SCENE2D &&
        encoding.quantization === TerrainQuantization$1.BITS12
      ) {
        // In 2D, the texture coordinates of the tile are interpolated over the rectangle to get the position in the vertex shader.
        // When the texture coordinates are quantized, error is introduced. This can be seen through the 1px wide cracking
        // between the quantized tiles in 2D. To compensate for the error, move the expand the rectangle in each direction by
        // half the error amount.
        var epsilon = (1.0 / (Math.pow(2.0, 12.0) - 1.0)) * 0.5;
        var widthEpsilon = (tileRectangle.z - tileRectangle.x) * epsilon;
        var heightEpsilon = (tileRectangle.w - tileRectangle.y) * epsilon;
        tileRectangle.x -= widthEpsilon;
        tileRectangle.y -= heightEpsilon;
        tileRectangle.z += widthEpsilon;
        tileRectangle.w += heightEpsilon;
      }

      if (projection instanceof WebMercatorProjection) {
        southLatitude = tile.rectangle.south;
        northLatitude = tile.rectangle.north;

        southMercatorY = WebMercatorProjection.geodeticLatitudeToMercatorAngle(
          southLatitude
        );

        oneOverMercatorHeight =
          1.0 /
          (WebMercatorProjection.geodeticLatitudeToMercatorAngle(northLatitude) -
            southMercatorY);

        useWebMercatorProjection = true;
      }
    }

    var surfaceShaderSetOptions = surfaceShaderSetOptionsScratch;
    surfaceShaderSetOptions.frameState = frameState;
    surfaceShaderSetOptions.surfaceTile = surfaceTile;
    surfaceShaderSetOptions.showReflectiveOcean = showReflectiveOcean;
    surfaceShaderSetOptions.showOceanWaves = showOceanWaves;
    surfaceShaderSetOptions.enableLighting = tileProvider.enableLighting;
    surfaceShaderSetOptions.dynamicAtmosphereLighting =
      tileProvider.dynamicAtmosphereLighting;
    surfaceShaderSetOptions.dynamicAtmosphereLightingFromSun =
      tileProvider.dynamicAtmosphereLightingFromSun;
    surfaceShaderSetOptions.showGroundAtmosphere = showGroundAtmosphere;
    surfaceShaderSetOptions.perFragmentGroundAtmosphere = perFragmentGroundAtmosphere;
    surfaceShaderSetOptions.hasVertexNormals = hasVertexNormals;
    surfaceShaderSetOptions.useWebMercatorProjection = useWebMercatorProjection;
    surfaceShaderSetOptions.clippedByBoundaries = surfaceTile.clippedByBoundaries;

    var tileImageryCollection = surfaceTile.imagery;
    var imageryIndex = 0;
    var imageryLen = tileImageryCollection.length;

    var showSkirts =
      tileProvider.showSkirts && !cameraUnderground && !translucent;
    var backFaceCulling =
      tileProvider.backFaceCulling && !cameraUnderground && !translucent;
    var firstPassRenderState = backFaceCulling
      ? tileProvider._renderState
      : tileProvider._disableCullingRenderState;
    var otherPassesRenderState = backFaceCulling
      ? tileProvider._blendRenderState
      : tileProvider._disableCullingBlendRenderState;
    var renderState = firstPassRenderState;

    var initialColor = tileProvider._firstPassInitialColor;

    var context = frameState.context;

    if (!defined(tileProvider._debug.boundingSphereTile)) {
      debugDestroyPrimitive();
    }

    var materialUniformMapChanged =
      tileProvider._materialUniformMap !== tileProvider.materialUniformMap;
    if (materialUniformMapChanged) {
      tileProvider._materialUniformMap = tileProvider.materialUniformMap;
      var drawCommandsLength = tileProvider._drawCommands.length;
      for (var i = 0; i < drawCommandsLength; ++i) {
        tileProvider._uniformMaps[i] = createTileUniformMap(
          frameState,
          tileProvider
        );
      }
    }

    do {
      var numberOfDayTextures = 0;

      var command;
      var uniformMap;

      if (tileProvider._drawCommands.length <= tileProvider._usedDrawCommands) {
        command = new DrawCommand();
        command.owner = tile;
        command.cull = false;
        command.boundingVolume = new BoundingSphere();
        command.orientedBoundingBox = undefined;

        uniformMap = createTileUniformMap(frameState, tileProvider);

        tileProvider._drawCommands.push(command);
        tileProvider._uniformMaps.push(uniformMap);
      } else {
        command = tileProvider._drawCommands[tileProvider._usedDrawCommands];
        uniformMap = tileProvider._uniformMaps[tileProvider._usedDrawCommands];
      }

      command.owner = tile;

      ++tileProvider._usedDrawCommands;

      if (tile === tileProvider._debug.boundingSphereTile) {
        var obb = surfaceTile.orientedBoundingBox;
        // If a debug primitive already exists for this tile, it will not be
        // re-created, to avoid allocation every frame. If it were possible
        // to have more than one selected tile, this would have to change.
        if (defined(obb)) {
          getDebugOrientedBoundingBox(obb, Color.RED).update(frameState);
        } else if (defined(mesh) && defined(mesh.boundingSphere3D)) {
          getDebugBoundingSphere(mesh.boundingSphere3D, Color.RED).update(
            frameState
          );
        }
      }

      var uniformMapProperties = uniformMap.properties;
      Cartesian4.clone(initialColor, uniformMapProperties.initialColor);
      uniformMapProperties.oceanNormalMap = oceanNormalMap;
      uniformMapProperties.lightingFadeDistance.x =
        tileProvider.lightingFadeOutDistance;
      uniformMapProperties.lightingFadeDistance.y =
        tileProvider.lightingFadeInDistance;
      uniformMapProperties.nightFadeDistance.x =
        tileProvider.nightFadeOutDistance;
      uniformMapProperties.nightFadeDistance.y = tileProvider.nightFadeInDistance;
      uniformMapProperties.zoomedOutOceanSpecularIntensity =
        tileProvider.zoomedOutOceanSpecularIntensity;

      var frontFaceAlphaByDistanceFinal = cameraUnderground
        ? backFaceAlphaByDistance
        : frontFaceAlphaByDistance;
      var backFaceAlphaByDistanceFinal = cameraUnderground
        ? frontFaceAlphaByDistance
        : backFaceAlphaByDistance;

      if (defined(frontFaceAlphaByDistanceFinal)) {
        Cartesian4.fromElements(
          frontFaceAlphaByDistanceFinal.near,
          frontFaceAlphaByDistanceFinal.nearValue,
          frontFaceAlphaByDistanceFinal.far,
          frontFaceAlphaByDistanceFinal.farValue,
          uniformMapProperties.frontFaceAlphaByDistance
        );
        Cartesian4.fromElements(
          backFaceAlphaByDistanceFinal.near,
          backFaceAlphaByDistanceFinal.nearValue,
          backFaceAlphaByDistanceFinal.far,
          backFaceAlphaByDistanceFinal.farValue,
          uniformMapProperties.backFaceAlphaByDistance
        );
      }

      Cartesian4.fromElements(
        undergroundColorAlphaByDistance.near,
        undergroundColorAlphaByDistance.nearValue,
        undergroundColorAlphaByDistance.far,
        undergroundColorAlphaByDistance.farValue,
        uniformMapProperties.undergroundColorAlphaByDistance
      );
      Color.clone(undergroundColor, uniformMapProperties.undergroundColor);

      var highlightFillTile =
        !defined(surfaceTile.vertexArray) &&
        defined(tileProvider.fillHighlightColor) &&
        tileProvider.fillHighlightColor.alpha > 0.0;
      if (highlightFillTile) {
        Color.clone(
          tileProvider.fillHighlightColor,
          uniformMapProperties.fillHighlightColor
        );
      }

      uniformMapProperties.center3D = mesh.center;
      Cartesian3.clone(rtc, uniformMapProperties.rtc);

      Cartesian4.clone(tileRectangle, uniformMapProperties.tileRectangle);
      uniformMapProperties.southAndNorthLatitude.x = southLatitude;
      uniformMapProperties.southAndNorthLatitude.y = northLatitude;
      uniformMapProperties.southMercatorYAndOneOverHeight.x = southMercatorY;
      uniformMapProperties.southMercatorYAndOneOverHeight.y = oneOverMercatorHeight;

      // Convert tile limiter rectangle from cartographic to texture space using the tileRectangle.
      var localizedCartographicLimitRectangle = localizedCartographicLimitRectangleScratch;
      var cartographicLimitRectangle = clipRectangleAntimeridian(
        tile.rectangle,
        tileProvider.cartographicLimitRectangle
      );

      var localizedTranslucencyRectangle = localizedTranslucencyRectangleScratch;
      var clippedTranslucencyRectangle = clipRectangleAntimeridian(
        tile.rectangle,
        translucencyRectangle
      );

      Cartesian3.fromElements(
        hueShift,
        saturationShift,
        brightnessShift,
        uniformMapProperties.hsbShift
      );

      var cartographicTileRectangle = tile.rectangle;
      var inverseTileWidth = 1.0 / cartographicTileRectangle.width;
      var inverseTileHeight = 1.0 / cartographicTileRectangle.height;
      localizedCartographicLimitRectangle.x =
        (cartographicLimitRectangle.west - cartographicTileRectangle.west) *
        inverseTileWidth;
      localizedCartographicLimitRectangle.y =
        (cartographicLimitRectangle.south - cartographicTileRectangle.south) *
        inverseTileHeight;
      localizedCartographicLimitRectangle.z =
        (cartographicLimitRectangle.east - cartographicTileRectangle.west) *
        inverseTileWidth;
      localizedCartographicLimitRectangle.w =
        (cartographicLimitRectangle.north - cartographicTileRectangle.south) *
        inverseTileHeight;

      Cartesian4.clone(
        localizedCartographicLimitRectangle,
        uniformMapProperties.localizedCartographicLimitRectangle
      );

      localizedTranslucencyRectangle.x =
        (clippedTranslucencyRectangle.west - cartographicTileRectangle.west) *
        inverseTileWidth;
      localizedTranslucencyRectangle.y =
        (clippedTranslucencyRectangle.south - cartographicTileRectangle.south) *
        inverseTileHeight;
      localizedTranslucencyRectangle.z =
        (clippedTranslucencyRectangle.east - cartographicTileRectangle.west) *
        inverseTileWidth;
      localizedTranslucencyRectangle.w =
        (clippedTranslucencyRectangle.north - cartographicTileRectangle.south) *
        inverseTileHeight;

      Cartesian4.clone(
        localizedTranslucencyRectangle,
        uniformMapProperties.localizedTranslucencyRectangle
      );

      // For performance, use fog in the shader only when the tile is in fog.
      var applyFog =
        enableFog &&
        CesiumMath.fog(tile._distance, frameState.fog.density) >
          CesiumMath.EPSILON3;
      colorCorrect = colorCorrect && (applyFog || showGroundAtmosphere);

      var applyBrightness = false;
      var applyContrast = false;
      var applyHue = false;
      var applySaturation = false;
      var applyGamma = false;
      var applyAlpha = false;
      var applyDayNightAlpha = false;
      var applySplit = false;
      var applyCutout = false;
      var applyColorToAlpha = false;

      while (numberOfDayTextures < maxTextures && imageryIndex < imageryLen) {
        var tileImagery = tileImageryCollection[imageryIndex];
        var imagery = tileImagery.readyImagery;
        ++imageryIndex;

        if (!defined(imagery) || imagery.imageryLayer.alpha === 0.0) {
          continue;
        }

        var texture = tileImagery.useWebMercatorT
          ? imagery.textureWebMercator
          : imagery.texture;

        //>>includeStart('debug', pragmas.debug);
        if (!defined(texture)) {
          // Our "ready" texture isn't actually ready.  This should never happen.
          //
          // Side note: It IS possible for it to not be in the READY ImageryState, though.
          // This can happen when a single imagery tile is shared by two terrain tiles (common)
          // and one of them (A) needs a geographic version of the tile because it is near the poles,
          // and the other (B) does not.  B can and will transition the imagery tile to the READY state
          // without reprojecting to geographic.  Then, later, A will deem that same tile not-ready-yet
          // because it only has the Web Mercator texture, and flip it back to the TRANSITIONING state.
          // The imagery tile won't be in the READY state anymore, but it's still READY enough for B's
          // purposes.
          throw new DeveloperError("readyImagery is not actually ready!");
        }
        //>>includeEnd('debug');

        var imageryLayer = imagery.imageryLayer;

        if (!defined(tileImagery.textureTranslationAndScale)) {
          tileImagery.textureTranslationAndScale = imageryLayer._calculateTextureTranslationAndScale(
            tile,
            tileImagery
          );
        }

        uniformMapProperties.dayTextures[numberOfDayTextures] = texture;
        uniformMapProperties.dayTextureTranslationAndScale[numberOfDayTextures] =
          tileImagery.textureTranslationAndScale;
        uniformMapProperties.dayTextureTexCoordsRectangle[numberOfDayTextures] =
          tileImagery.textureCoordinateRectangle;
        uniformMapProperties.dayTextureUseWebMercatorT[numberOfDayTextures] =
          tileImagery.useWebMercatorT;

        uniformMapProperties.dayTextureAlpha[numberOfDayTextures] =
          imageryLayer.alpha;
        applyAlpha =
          applyAlpha ||
          uniformMapProperties.dayTextureAlpha[numberOfDayTextures] !== 1.0;

        uniformMapProperties.dayTextureNightAlpha[numberOfDayTextures] =
          imageryLayer.nightAlpha;
        applyDayNightAlpha =
          applyDayNightAlpha ||
          uniformMapProperties.dayTextureNightAlpha[numberOfDayTextures] !== 1.0;

        uniformMapProperties.dayTextureDayAlpha[numberOfDayTextures] =
          imageryLayer.dayAlpha;
        applyDayNightAlpha =
          applyDayNightAlpha ||
          uniformMapProperties.dayTextureDayAlpha[numberOfDayTextures] !== 1.0;

        uniformMapProperties.dayTextureBrightness[numberOfDayTextures] =
          imageryLayer.brightness;
        applyBrightness =
          applyBrightness ||
          uniformMapProperties.dayTextureBrightness[numberOfDayTextures] !==
            ImageryLayer.DEFAULT_BRIGHTNESS;

        uniformMapProperties.dayTextureContrast[numberOfDayTextures] =
          imageryLayer.contrast;
        applyContrast =
          applyContrast ||
          uniformMapProperties.dayTextureContrast[numberOfDayTextures] !==
            ImageryLayer.DEFAULT_CONTRAST;

        uniformMapProperties.dayTextureHue[numberOfDayTextures] =
          imageryLayer.hue;
        applyHue =
          applyHue ||
          uniformMapProperties.dayTextureHue[numberOfDayTextures] !==
            ImageryLayer.DEFAULT_HUE;

        uniformMapProperties.dayTextureSaturation[numberOfDayTextures] =
          imageryLayer.saturation;
        applySaturation =
          applySaturation ||
          uniformMapProperties.dayTextureSaturation[numberOfDayTextures] !==
            ImageryLayer.DEFAULT_SATURATION;

        uniformMapProperties.dayTextureOneOverGamma[numberOfDayTextures] =
          1.0 / imageryLayer.gamma;
        applyGamma =
          applyGamma ||
          uniformMapProperties.dayTextureOneOverGamma[numberOfDayTextures] !==
            1.0 / ImageryLayer.DEFAULT_GAMMA;

        uniformMapProperties.dayTextureSplit[numberOfDayTextures] =
          imageryLayer.splitDirection;
        applySplit =
          applySplit ||
          uniformMapProperties.dayTextureSplit[numberOfDayTextures] !== 0.0;

        // Update cutout rectangle
        var dayTextureCutoutRectangle =
          uniformMapProperties.dayTextureCutoutRectangles[numberOfDayTextures];
        if (!defined(dayTextureCutoutRectangle)) {
          dayTextureCutoutRectangle = uniformMapProperties.dayTextureCutoutRectangles[
            numberOfDayTextures
          ] = new Cartesian4();
        }

        Cartesian4.clone(Cartesian4.ZERO, dayTextureCutoutRectangle);
        if (defined(imageryLayer.cutoutRectangle)) {
          var cutoutRectangle = clipRectangleAntimeridian(
            cartographicTileRectangle,
            imageryLayer.cutoutRectangle
          );
          var intersection = Rectangle.simpleIntersection(
            cutoutRectangle,
            cartographicTileRectangle,
            rectangleIntersectionScratch
          );
          applyCutout = defined(intersection) || applyCutout;

          dayTextureCutoutRectangle.x =
            (cutoutRectangle.west - cartographicTileRectangle.west) *
            inverseTileWidth;
          dayTextureCutoutRectangle.y =
            (cutoutRectangle.south - cartographicTileRectangle.south) *
            inverseTileHeight;
          dayTextureCutoutRectangle.z =
            (cutoutRectangle.east - cartographicTileRectangle.west) *
            inverseTileWidth;
          dayTextureCutoutRectangle.w =
            (cutoutRectangle.north - cartographicTileRectangle.south) *
            inverseTileHeight;
        }

        // Update color to alpha
        var colorToAlpha =
          uniformMapProperties.colorsToAlpha[numberOfDayTextures];
        if (!defined(colorToAlpha)) {
          colorToAlpha = uniformMapProperties.colorsToAlpha[
            numberOfDayTextures
          ] = new Cartesian4();
        }

        var hasColorToAlpha =
          defined(imageryLayer.colorToAlpha) &&
          imageryLayer.colorToAlphaThreshold > 0.0;
        applyColorToAlpha = applyColorToAlpha || hasColorToAlpha;

        if (hasColorToAlpha) {
          var color = imageryLayer.colorToAlpha;
          colorToAlpha.x = color.red;
          colorToAlpha.y = color.green;
          colorToAlpha.z = color.blue;
          colorToAlpha.w = imageryLayer.colorToAlphaThreshold;
        } else {
          colorToAlpha.w = -1.0;
        }

        if (defined(imagery.credits)) {
          var credits = imagery.credits;
          for (
            var creditIndex = 0, creditLength = credits.length;
            creditIndex < creditLength;
            ++creditIndex
          ) {
            creditDisplay.addCredit(credits[creditIndex]);
          }
        }

        ++numberOfDayTextures;
      }

      // trim texture array to the used length so we don't end up using old textures
      // which might get destroyed eventually
      uniformMapProperties.dayTextures.length = numberOfDayTextures;
      uniformMapProperties.waterMask = waterMaskTexture;
      Cartesian4.clone(
        waterMaskTranslationAndScale,
        uniformMapProperties.waterMaskTranslationAndScale
      );

      uniformMapProperties.minMaxHeight.x = encoding.minimumHeight;
      uniformMapProperties.minMaxHeight.y = encoding.maximumHeight;
      Matrix4.clone(encoding.matrix, uniformMapProperties.scaleAndBias);

      // update clipping planes
      var clippingPlanes = tileProvider._clippingPlanes;
      var clippingPlanesEnabled =
        defined(clippingPlanes) && clippingPlanes.enabled && tile.isClipped;
      if (clippingPlanesEnabled) {
        uniformMapProperties.clippingPlanesEdgeColor = Color.clone(
          clippingPlanes.edgeColor,
          uniformMapProperties.clippingPlanesEdgeColor
        );
        uniformMapProperties.clippingPlanesEdgeWidth = clippingPlanes.edgeWidth;
      }

      surfaceShaderSetOptions.numberOfDayTextures = numberOfDayTextures;
      surfaceShaderSetOptions.applyBrightness = applyBrightness;
      surfaceShaderSetOptions.applyContrast = applyContrast;
      surfaceShaderSetOptions.applyHue = applyHue;
      surfaceShaderSetOptions.applySaturation = applySaturation;
      surfaceShaderSetOptions.applyGamma = applyGamma;
      surfaceShaderSetOptions.applyAlpha = applyAlpha;
      surfaceShaderSetOptions.applyDayNightAlpha = applyDayNightAlpha;
      surfaceShaderSetOptions.applySplit = applySplit;
      surfaceShaderSetOptions.enableFog = applyFog;
      surfaceShaderSetOptions.enableClippingPlanes = clippingPlanesEnabled;
      surfaceShaderSetOptions.clippingPlanes = clippingPlanes;
      surfaceShaderSetOptions.hasImageryLayerCutout = applyCutout;
      surfaceShaderSetOptions.colorCorrect = colorCorrect;
      surfaceShaderSetOptions.highlightFillTile = highlightFillTile;
      surfaceShaderSetOptions.colorToAlpha = applyColorToAlpha;
      surfaceShaderSetOptions.showUndergroundColor = showUndergroundColor;
      surfaceShaderSetOptions.translucent = translucent;

      var count = surfaceTile.renderedMesh.indices.length;
      if (!showSkirts) {
        count = surfaceTile.renderedMesh.indexCountWithoutSkirts;
      }

      command.shaderProgram = tileProvider._surfaceShaderSet.getShaderProgram(
        surfaceShaderSetOptions
      );
      command.castShadows = castShadows;
      command.receiveShadows = receiveShadows;
      command.renderState = renderState;
      command.primitiveType = PrimitiveType$1.TRIANGLES;
      command.vertexArray =
        surfaceTile.vertexArray || surfaceTile.fill.vertexArray;
      command.count = count;
      command.uniformMap = uniformMap;
      command.pass = Pass$1.GLOBE;

      if (tileProvider._debug.wireframe) {
        createWireframeVertexArrayIfNecessary(context, tileProvider, tile);
        if (defined(surfaceTile.wireframeVertexArray)) {
          command.vertexArray = surfaceTile.wireframeVertexArray;
          command.primitiveType = PrimitiveType$1.LINES;
          command.count = count * 2;
        }
      }

      var boundingVolume = command.boundingVolume;
      var orientedBoundingBox = command.orientedBoundingBox;

      if (frameState.mode !== SceneMode$1.SCENE3D) {
        var tileBoundingRegion = surfaceTile.tileBoundingRegion;
        BoundingSphere.fromRectangleWithHeights2D(
          tile.rectangle,
          frameState.mapProjection,
          tileBoundingRegion.minimumHeight,
          tileBoundingRegion.maximumHeight,
          boundingVolume
        );
        Cartesian3.fromElements(
          boundingVolume.center.z,
          boundingVolume.center.x,
          boundingVolume.center.y,
          boundingVolume.center
        );

        if (frameState.mode === SceneMode$1.MORPHING) {
          boundingVolume = BoundingSphere.union(
            mesh.boundingSphere3D,
            boundingVolume,
            boundingVolume
          );
        }
      } else {
        command.boundingVolume = BoundingSphere.clone(
          mesh.boundingSphere3D,
          boundingVolume
        );
        command.orientedBoundingBox = OrientedBoundingBox.clone(
          surfaceTile.orientedBoundingBox,
          orientedBoundingBox
        );
      }

      command.dirty = true;

      if (translucent) {
        globeTranslucencyState.updateDerivedCommands(command, frameState);
      }

      pushCommand(command, frameState);

      renderState = otherPassesRenderState;
      initialColor = otherPassesInitialColor;
    } while (imageryIndex < imageryLen);
  }

  /**
   * Properties for controlling globe translucency.
   *
   * @alias GlobeTranslucency
   * @constructor
   */
  function GlobeTranslucency() {
    this._enabled = false;
    this._frontFaceAlpha = 1.0;
    this._frontFaceAlphaByDistance = undefined;
    this._backFaceAlpha = 1.0;
    this._backFaceAlphaByDistance = undefined;
    this._rectangle = Rectangle.clone(Rectangle.MAX_VALUE);
  }

  Object.defineProperties(GlobeTranslucency.prototype, {
    /**
     * When true, the globe is rendered as a translucent surface.
     * <br /><br />
     * The alpha is computed by blending {@link Globe#material}, {@link Globe#imageryLayers},
     * and {@link Globe#baseColor}, all of which may contain translucency, and then multiplying by
     * {@link GlobeTranslucency#frontFaceAlpha} and {@link GlobeTranslucency#frontFaceAlphaByDistance} for front faces and
     * {@link GlobeTranslucency#backFaceAlpha} and {@link GlobeTranslucency#backFaceAlphaByDistance} for back faces.
     * When the camera is underground back faces and front faces are swapped, i.e. back-facing geometry
     * is considered front facing.
     * <br /><br />
     * Translucency is disabled by default.
     *
     * @memberof GlobeTranslucency.prototype
     *
     * @type {Boolean}
     * @default false
     *
     * @see GlobeTranslucency#frontFaceAlpha
     * @see GlobeTranslucency#frontFaceAlphaByDistance
     * @see GlobeTranslucency#backFaceAlpha
     * @see GlobeTranslucency#backFaceAlphaByDistance
     */
    enabled: {
      get: function () {
        return this._enabled;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.bool("enabled", value);
        //>>includeEnd('debug');
        this._enabled = value;
      },
    },

    /**
     * A constant translucency to apply to front faces of the globe.
     * <br /><br />
     * {@link GlobeTranslucency#enabled} must be set to true for this option to take effect.
     *
     * @memberof GlobeTranslucency.prototype
     *
     * @type {Number}
     * @default 1.0
     *
     * @see GlobeTranslucency#enabled
     * @see GlobeTranslucency#frontFaceAlphaByDistance
     *
     * @example
     * // Set front face translucency to 0.5.
     * globe.translucency.frontFaceAlpha = 0.5;
     * globe.translucency.enabled = true;
     */
    frontFaceAlpha: {
      get: function () {
        return this._frontFaceAlpha;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("frontFaceAlpha", value, 0.0);
        Check.typeOf.number.lessThanOrEquals("frontFaceAlpha", value, 1.0);
        //>>includeEnd('debug');
        this._frontFaceAlpha = value;
      },
    },
    /**
     * Gets or sets near and far translucency properties of front faces of the globe based on the distance to the camera.
     * The translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the translucency remains clamped to the nearest bound.  If undefined,
     * frontFaceAlphaByDistance will be disabled.
     * <br /><br />
     * {@link GlobeTranslucency#enabled} must be set to true for this option to take effect.
     *
     * @memberof GlobeTranslucency.prototype
     *
     * @type {NearFarScalar}
     * @default undefined
     *
     * @see GlobeTranslucency#enabled
     * @see GlobeTranslucency#frontFaceAlpha
     *
     * @example
     * // Example 1.
     * // Set front face translucency to 0.5 when the
     * // camera is 1500 meters from the surface and 1.0
     * // as the camera distance approaches 8.0e6 meters.
     * globe.translucency.frontFaceAlphaByDistance = new Cesium.NearFarScalar(1.5e2, 0.5, 8.0e6, 1.0);
     * globe.translucency.enabled = true;
     *
     * @example
     * // Example 2.
     * // Disable front face translucency by distance
     * globe.translucency.frontFaceAlphaByDistance = undefined;
     */
    frontFaceAlphaByDistance: {
      get: function () {
        return this._frontFaceAlphaByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far < value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');
        this._frontFaceAlphaByDistance = NearFarScalar.clone(
          value,
          this._frontFaceAlphaByDistance
        );
      },
    },

    /**
     * A constant translucency to apply to back faces of the globe.
     * <br /><br />
     * {@link GlobeTranslucency#enabled} must be set to true for this option to take effect.
     *
     * @memberof GlobeTranslucency.prototype
     *
     * @type {Number}
     * @default 1.0
     *
     * @see GlobeTranslucency#enabled
     * @see GlobeTranslucency#backFaceAlphaByDistance
     *
     * @example
     * // Set back face translucency to 0.5.
     * globe.translucency.backFaceAlpha = 0.5;
     * globe.translucency.enabled = true;
     */
    backFaceAlpha: {
      get: function () {
        return this._backFaceAlpha;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("backFaceAlpha", value, 0.0);
        Check.typeOf.number.lessThanOrEquals("backFaceAlpha", value, 1.0);
        //>>includeEnd('debug');
        this._backFaceAlpha = value;
      },
    },
    /**
     * Gets or sets near and far translucency properties of back faces of the globe based on the distance to the camera.
     * The translucency will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the translucency remains clamped to the nearest bound.  If undefined,
     * backFaceAlphaByDistance will be disabled.
     * <br /><br />
     * {@link GlobeTranslucency#enabled} must be set to true for this option to take effect.
     *
     * @memberof GlobeTranslucency.prototype
     *
     * @type {NearFarScalar}
     * @default undefined
     *
     * @see GlobeTranslucency#enabled
     * @see GlobeTranslucency#backFaceAlpha
     *
     * @example
     * // Example 1.
     * // Set back face translucency to 0.5 when the
     * // camera is 1500 meters from the surface and 1.0
     * // as the camera distance approaches 8.0e6 meters.
     * globe.translucency.backFaceAlphaByDistance = new Cesium.NearFarScalar(1.5e2, 0.5, 8.0e6, 1.0);
     * globe.translucency.enabled = true;
     *
     * @example
     * // Example 2.
     * // Disable back face translucency by distance
     * globe.translucency.backFaceAlphaByDistance = undefined;
     */
    backFaceAlphaByDistance: {
      get: function () {
        return this._backFaceAlphaByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far < value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');
        this._backFaceAlphaByDistance = NearFarScalar.clone(
          value,
          this._backFaceAlphaByDistance
        );
      },
    },

    /**
     * A property specifying a {@link Rectangle} used to limit translucency to a cartographic area.
     * Defaults to the maximum extent of cartographic coordinates.
     *
     * @memberof GlobeTranslucency.prototype
     *
     * @type {Rectangle}
     * @default {@link Rectangle.MAX_VALUE}
     */
    rectangle: {
      get: function () {
        return this._rectangle;
      },
      set: function (value) {
        if (!defined(value)) {
          value = Rectangle.clone(Rectangle.MAX_VALUE);
        }
        Rectangle.clone(value, this._rectangle);
      },
    },
  });

  /**
   * An ordered collection of imagery layers.
   *
   * @alias ImageryLayerCollection
   * @constructor
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Imagery%20Adjustment.html|Cesium Sandcastle Imagery Adjustment Demo}
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Imagery%20Layers%20Manipulation.html|Cesium Sandcastle Imagery Manipulation Demo}
   */
  function ImageryLayerCollection() {
    this._layers = [];

    /**
     * An event that is raised when a layer is added to the collection.  Event handlers are passed the layer that
     * was added and the index at which it was added.
     * @type {Event}
     * @default Event()
     */
    this.layerAdded = new Event();

    /**
     * An event that is raised when a layer is removed from the collection.  Event handlers are passed the layer that
     * was removed and the index from which it was removed.
     * @type {Event}
     * @default Event()
     */
    this.layerRemoved = new Event();

    /**
     * An event that is raised when a layer changes position in the collection.  Event handlers are passed the layer that
     * was moved, its new index after the move, and its old index prior to the move.
     * @type {Event}
     * @default Event()
     */
    this.layerMoved = new Event();

    /**
     * An event that is raised when a layer is shown or hidden by setting the
     * {@link ImageryLayer#show} property.  Event handlers are passed a reference to this layer,
     * the index of the layer in the collection, and a flag that is true if the layer is now
     * shown or false if it is now hidden.
     *
     * @type {Event}
     * @default Event()
     */
    this.layerShownOrHidden = new Event();
  }

  Object.defineProperties(ImageryLayerCollection.prototype, {
    /**
     * Gets the number of layers in this collection.
     * @memberof ImageryLayerCollection.prototype
     * @type {Number}
     */
    length: {
      get: function () {
        return this._layers.length;
      },
    },
  });

  /**
   * Adds a layer to the collection.
   *
   * @param {ImageryLayer} layer the layer to add.
   * @param {Number} [index] the index to add the layer at.  If omitted, the layer will
   *                         be added on top of all existing layers.
   *
   * @exception {DeveloperError} index, if supplied, must be greater than or equal to zero and less than or equal to the number of the layers.
   */
  ImageryLayerCollection.prototype.add = function (layer, index) {
    var hasIndex = defined(index);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(layer)) {
      throw new DeveloperError("layer is required.");
    }
    if (hasIndex) {
      if (index < 0) {
        throw new DeveloperError("index must be greater than or equal to zero.");
      } else if (index > this._layers.length) {
        throw new DeveloperError(
          "index must be less than or equal to the number of layers."
        );
      }
    }
    //>>includeEnd('debug');

    if (!hasIndex) {
      index = this._layers.length;
      this._layers.push(layer);
    } else {
      this._layers.splice(index, 0, layer);
    }

    this._update();
    this.layerAdded.raiseEvent(layer, index);
  };

  /**
   * Creates a new layer using the given ImageryProvider and adds it to the collection.
   *
   * @param {ImageryProvider} imageryProvider the imagery provider to create a new layer for.
   * @param {Number} [index] the index to add the layer at.  If omitted, the layer will
   *                         added on top of all existing layers.
   * @returns {ImageryLayer} The newly created layer.
   */
  ImageryLayerCollection.prototype.addImageryProvider = function (
    imageryProvider,
    index
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(imageryProvider)) {
      throw new DeveloperError("imageryProvider is required.");
    }
    //>>includeEnd('debug');

    var layer = new ImageryLayer(imageryProvider);
    this.add(layer, index);
    return layer;
  };

  /**
   * Removes a layer from this collection, if present.
   *
   * @param {ImageryLayer} layer The layer to remove.
   * @param {Boolean} [destroy=true] whether to destroy the layers in addition to removing them.
   * @returns {Boolean} true if the layer was in the collection and was removed,
   *                    false if the layer was not in the collection.
   */
  ImageryLayerCollection.prototype.remove = function (layer, destroy) {
    destroy = defaultValue(destroy, true);

    var index = this._layers.indexOf(layer);
    if (index !== -1) {
      this._layers.splice(index, 1);

      this._update();

      this.layerRemoved.raiseEvent(layer, index);

      if (destroy) {
        layer.destroy();
      }

      return true;
    }

    return false;
  };

  /**
   * Removes all layers from this collection.
   *
   * @param {Boolean} [destroy=true] whether to destroy the layers in addition to removing them.
   */
  ImageryLayerCollection.prototype.removeAll = function (destroy) {
    destroy = defaultValue(destroy, true);

    var layers = this._layers;
    for (var i = 0, len = layers.length; i < len; i++) {
      var layer = layers[i];
      this.layerRemoved.raiseEvent(layer, i);

      if (destroy) {
        layer.destroy();
      }
    }

    this._layers = [];
  };

  /**
   * Checks to see if the collection contains a given layer.
   *
   * @param {ImageryLayer} layer the layer to check for.
   *
   * @returns {Boolean} true if the collection contains the layer, false otherwise.
   */
  ImageryLayerCollection.prototype.contains = function (layer) {
    return this.indexOf(layer) !== -1;
  };

  /**
   * Determines the index of a given layer in the collection.
   *
   * @param {ImageryLayer} layer The layer to find the index of.
   *
   * @returns {Number} The index of the layer in the collection, or -1 if the layer does not exist in the collection.
   */
  ImageryLayerCollection.prototype.indexOf = function (layer) {
    return this._layers.indexOf(layer);
  };

  /**
   * Gets a layer by index from the collection.
   *
   * @param {Number} index the index to retrieve.
   *
   * @returns {ImageryLayer} The imagery layer at the given index.
   */
  ImageryLayerCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.", "index");
    }
    //>>includeEnd('debug');

    return this._layers[index];
  };

  function getLayerIndex(layers, layer) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(layer)) {
      throw new DeveloperError("layer is required.");
    }
    //>>includeEnd('debug');

    var index = layers.indexOf(layer);

    //>>includeStart('debug', pragmas.debug);
    if (index === -1) {
      throw new DeveloperError("layer is not in this collection.");
    }
    //>>includeEnd('debug');

    return index;
  }

  function swapLayers(collection, i, j) {
    var arr = collection._layers;
    i = CesiumMath.clamp(i, 0, arr.length - 1);
    j = CesiumMath.clamp(j, 0, arr.length - 1);

    if (i === j) {
      return;
    }

    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;

    collection._update();

    collection.layerMoved.raiseEvent(temp, j, i);
  }

  /**
   * Raises a layer up one position in the collection.
   *
   * @param {ImageryLayer} layer the layer to move.
   *
   * @exception {DeveloperError} layer is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  ImageryLayerCollection.prototype.raise = function (layer) {
    var index = getLayerIndex(this._layers, layer);
    swapLayers(this, index, index + 1);
  };

  /**
   * Lowers a layer down one position in the collection.
   *
   * @param {ImageryLayer} layer the layer to move.
   *
   * @exception {DeveloperError} layer is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  ImageryLayerCollection.prototype.lower = function (layer) {
    var index = getLayerIndex(this._layers, layer);
    swapLayers(this, index, index - 1);
  };

  /**
   * Raises a layer to the top of the collection.
   *
   * @param {ImageryLayer} layer the layer to move.
   *
   * @exception {DeveloperError} layer is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  ImageryLayerCollection.prototype.raiseToTop = function (layer) {
    var index = getLayerIndex(this._layers, layer);
    if (index === this._layers.length - 1) {
      return;
    }
    this._layers.splice(index, 1);
    this._layers.push(layer);

    this._update();

    this.layerMoved.raiseEvent(layer, this._layers.length - 1, index);
  };

  /**
   * Lowers a layer to the bottom of the collection.
   *
   * @param {ImageryLayer} layer the layer to move.
   *
   * @exception {DeveloperError} layer is not in this collection.
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   */
  ImageryLayerCollection.prototype.lowerToBottom = function (layer) {
    var index = getLayerIndex(this._layers, layer);
    if (index === 0) {
      return;
    }
    this._layers.splice(index, 1);
    this._layers.splice(0, 0, layer);

    this._update();

    this.layerMoved.raiseEvent(layer, 0, index);
  };

  var applicableRectangleScratch = new Rectangle();

  /**
   * Asynchronously determines the imagery layer features that are intersected by a pick ray.  The intersected imagery
   * layer features are found by invoking {@link ImageryProvider#pickFeatures} for each imagery layer tile intersected
   * by the pick ray.  To compute a pick ray from a location on the screen, use {@link Camera.getPickRay}.
   *
   * @param {Ray} ray The ray to test for intersection.
   * @param {Scene} scene The scene.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise that resolves to an array of features intersected by the pick ray.
   *                                             If it can be quickly determined that no features are intersected (for example,
   *                                             because no active imagery providers support {@link ImageryProvider#pickFeatures}
   *                                             or because the pick ray does not intersect the surface), this function will
   *                                             return undefined.
   *
   * @example
   * var pickRay = viewer.camera.getPickRay(windowPosition);
   * var featuresPromise = viewer.imageryLayers.pickImageryLayerFeatures(pickRay, viewer.scene);
   * if (!Cesium.defined(featuresPromise)) {
   *     console.log('No features picked.');
   * } else {
   *     Cesium.when(featuresPromise, function(features) {
   *         // This function is called asynchronously when the list if picked features is available.
   *         console.log('Number of features: ' + features.length);
   *         if (features.length > 0) {
   *             console.log('First feature name: ' + features[0].name);
   *         }
   *     });
   * }
   */
  ImageryLayerCollection.prototype.pickImageryLayerFeatures = function (
    ray,
    scene
  ) {
    // Find the picked location on the globe.
    var pickedPosition = scene.globe.pick(ray, scene);
    if (!defined(pickedPosition)) {
      return undefined;
    }

    var pickedLocation = scene.globe.ellipsoid.cartesianToCartographic(
      pickedPosition
    );

    // Find the terrain tile containing the picked location.
    var tilesToRender = scene.globe._surface._tilesToRender;
    var pickedTile;

    for (
      var textureIndex = 0;
      !defined(pickedTile) && textureIndex < tilesToRender.length;
      ++textureIndex
    ) {
      var tile = tilesToRender[textureIndex];
      if (Rectangle.contains(tile.rectangle, pickedLocation)) {
        pickedTile = tile;
      }
    }

    if (!defined(pickedTile)) {
      return undefined;
    }

    // Pick against all attached imagery tiles containing the pickedLocation.
    var imageryTiles = pickedTile.data.imagery;

    var promises = [];
    var imageryLayers = [];
    for (var i = imageryTiles.length - 1; i >= 0; --i) {
      var terrainImagery = imageryTiles[i];
      var imagery = terrainImagery.readyImagery;
      if (!defined(imagery)) {
        continue;
      }
      var provider = imagery.imageryLayer.imageryProvider;
      if (!defined(provider.pickFeatures)) {
        continue;
      }

      if (!Rectangle.contains(imagery.rectangle, pickedLocation)) {
        continue;
      }

      // If this imagery came from a parent, it may not be applicable to its entire rectangle.
      // Check the textureCoordinateRectangle.
      var applicableRectangle = applicableRectangleScratch;

      var epsilon = 1 / 1024; // 1/4 of a pixel in a typical 256x256 tile.
      applicableRectangle.west = CesiumMath.lerp(
        pickedTile.rectangle.west,
        pickedTile.rectangle.east,
        terrainImagery.textureCoordinateRectangle.x - epsilon
      );
      applicableRectangle.east = CesiumMath.lerp(
        pickedTile.rectangle.west,
        pickedTile.rectangle.east,
        terrainImagery.textureCoordinateRectangle.z + epsilon
      );
      applicableRectangle.south = CesiumMath.lerp(
        pickedTile.rectangle.south,
        pickedTile.rectangle.north,
        terrainImagery.textureCoordinateRectangle.y - epsilon
      );
      applicableRectangle.north = CesiumMath.lerp(
        pickedTile.rectangle.south,
        pickedTile.rectangle.north,
        terrainImagery.textureCoordinateRectangle.w + epsilon
      );
      if (!Rectangle.contains(applicableRectangle, pickedLocation)) {
        continue;
      }

      var promise = provider.pickFeatures(
        imagery.x,
        imagery.y,
        imagery.level,
        pickedLocation.longitude,
        pickedLocation.latitude
      );
      if (!defined(promise)) {
        continue;
      }

      promises.push(promise);
      imageryLayers.push(imagery.imageryLayer);
    }

    if (promises.length === 0) {
      return undefined;
    }

    return when.all(promises, function (results) {
      var features = [];

      for (var resultIndex = 0; resultIndex < results.length; ++resultIndex) {
        var result = results[resultIndex];
        var image = imageryLayers[resultIndex];

        if (defined(result) && result.length > 0) {
          for (
            var featureIndex = 0;
            featureIndex < result.length;
            ++featureIndex
          ) {
            var feature = result[featureIndex];
            feature.imageryLayer = image;

            // For features without a position, use the picked location.
            if (!defined(feature.position)) {
              feature.position = pickedLocation;
            }

            features.push(feature);
          }
        }
      }

      return features;
    });
  };

  /**
   * Updates frame state to execute any queued texture re-projections.
   *
   * @private
   *
   * @param {FrameState} frameState The frameState.
   */
  ImageryLayerCollection.prototype.queueReprojectionCommands = function (
    frameState
  ) {
    var layers = this._layers;
    for (var i = 0, len = layers.length; i < len; ++i) {
      layers[i].queueReprojectionCommands(frameState);
    }
  };

  /**
   * Cancels re-projection commands queued for the next frame.
   *
   * @private
   */
  ImageryLayerCollection.prototype.cancelReprojections = function () {
    var layers = this._layers;
    for (var i = 0, len = layers.length; i < len; ++i) {
      layers[i].cancelReprojections();
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} true if this object was destroyed; otherwise, false.
   *
   * @see ImageryLayerCollection#destroy
   */
  ImageryLayerCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by all layers in this collection.  Explicitly destroying this
   * object allows for deterministic release of WebGL resources, instead of relying on the garbage
   * collector.
   * <br /><br />
   * Once this object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * layerCollection = layerCollection && layerCollection.destroy();
   *
   * @see ImageryLayerCollection#isDestroyed
   */
  ImageryLayerCollection.prototype.destroy = function () {
    this.removeAll(true);
    return destroyObject(this);
  };

  ImageryLayerCollection.prototype._update = function () {
    var isBaseLayer = true;
    var layers = this._layers;
    var layersShownOrHidden;
    var layer;
    var i, len;
    for (i = 0, len = layers.length; i < len; ++i) {
      layer = layers[i];

      layer._layerIndex = i;

      if (layer.show) {
        layer._isBaseLayer = isBaseLayer;
        isBaseLayer = false;
      } else {
        layer._isBaseLayer = false;
      }

      if (layer.show !== layer._show) {
        if (defined(layer._show)) {
          if (!defined(layersShownOrHidden)) {
            layersShownOrHidden = [];
          }
          layersShownOrHidden.push(layer);
        }
        layer._show = layer.show;
      }
    }

    if (defined(layersShownOrHidden)) {
      for (i = 0, len = layersShownOrHidden.length; i < len; ++i) {
        layer = layersShownOrHidden[i];
        this.layerShownOrHidden.raiseEvent(layer, layer._layerIndex, layer.show);
      }
    }
  };

  /**
   * A set of occluders that can be used to test quadtree tiles for occlusion.
   *
   * @alias QuadtreeOccluders
   * @constructor
   * @private
   *
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.WGS84] The ellipsoid that potentially occludes tiles.
   */
  function QuadtreeOccluders(options) {
    this._ellipsoid = new EllipsoidalOccluder(options.ellipsoid, Cartesian3.ZERO);
  }

  Object.defineProperties(QuadtreeOccluders.prototype, {
    /**
     * Gets the {@link EllipsoidalOccluder} that can be used to determine if a point is
     * occluded by an {@link Ellipsoid}.
     * @type {EllipsoidalOccluder}
     * @memberof QuadtreeOccluders.prototype
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
  });

  /**
   * A single tile in a {@link QuadtreePrimitive}.
   *
   * @alias QuadtreeTile
   * @constructor
   * @private
   *
   * @param {Number} options.level The level of the tile in the quadtree.
   * @param {Number} options.x The X coordinate of the tile in the quadtree.  0 is the westernmost tile.
   * @param {Number} options.y The Y coordinate of the tile in the quadtree.  0 is the northernmost tile.
   * @param {TilingScheme} options.tilingScheme The tiling scheme in which this tile exists.
   * @param {QuadtreeTile} [options.parent] This tile's parent, or undefined if this is a root tile.
   */
  function QuadtreeTile(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!defined(options.x)) {
      throw new DeveloperError("options.x is required.");
    } else if (!defined(options.y)) {
      throw new DeveloperError("options.y is required.");
    } else if (options.x < 0 || options.y < 0) {
      throw new DeveloperError(
        "options.x and options.y must be greater than or equal to zero."
      );
    }
    if (!defined(options.level)) {
      throw new DeveloperError(
        "options.level is required and must be greater than or equal to zero."
      );
    }
    if (!defined(options.tilingScheme)) {
      throw new DeveloperError("options.tilingScheme is required.");
    }
    //>>includeEnd('debug');

    this._tilingScheme = options.tilingScheme;
    this._x = options.x;
    this._y = options.y;
    this._level = options.level;
    this._parent = options.parent;
    this._rectangle = this._tilingScheme.tileXYToRectangle(
      this._x,
      this._y,
      this._level
    );

    this._southwestChild = undefined;
    this._southeastChild = undefined;
    this._northwestChild = undefined;
    this._northeastChild = undefined;

    // TileReplacementQueue gets/sets these private properties.
    this.replacementPrevious = undefined;
    this.replacementNext = undefined;

    // The distance from the camera to this tile, updated when the tile is selected
    // for rendering.  We can get rid of this if we have a better way to sort by
    // distance - for example, by using the natural ordering of a quadtree.
    // QuadtreePrimitive gets/sets this private property.
    this._distance = 0.0;
    this._loadPriority = 0.0;

    this._customData = [];
    this._frameUpdated = undefined;
    this._lastSelectionResult = TileSelectionResult.NONE;
    this._lastSelectionResultFrame = undefined;
    this._loadedCallbacks = {};

    /**
     * Gets or sets the current state of the tile in the tile load pipeline.
     * @type {QuadtreeTileLoadState}
     * @default {@link QuadtreeTileLoadState.START}
     */
    this.state = QuadtreeTileLoadState$1.START;

    /**
     * Gets or sets a value indicating whether or not the tile is currently renderable.
     * @type {Boolean}
     * @default false
     */
    this.renderable = false;

    /**
     * Gets or set a value indicating whether or not the tile was entirely upsampled from its
     * parent tile.  If all four children of a parent tile were upsampled from the parent,
     * we will render the parent instead of the children even if the LOD indicates that
     * the children would be preferable.
     * @type {Boolean}
     * @default false
     */
    this.upsampledFromParent = false;

    /**
     * Gets or sets the additional data associated with this tile.  The exact content is specific to the
     * {@link QuadtreeTileProvider}.
     * @type {Object}
     * @default undefined
     */
    this.data = undefined;
  }

  /**
   * Creates a rectangular set of tiles for level of detail zero, the coarsest, least detailed level.
   *
   * @memberof QuadtreeTile
   *
   * @param {TilingScheme} tilingScheme The tiling scheme for which the tiles are to be created.
   * @returns {QuadtreeTile[]} An array containing the tiles at level of detail zero, starting with the
   * tile in the northwest corner and followed by the tile (if any) to its east.
   */
  QuadtreeTile.createLevelZeroTiles = function (tilingScheme) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(tilingScheme)) {
      throw new DeveloperError("tilingScheme is required.");
    }
    //>>includeEnd('debug');

    var numberOfLevelZeroTilesX = tilingScheme.getNumberOfXTilesAtLevel(0);
    var numberOfLevelZeroTilesY = tilingScheme.getNumberOfYTilesAtLevel(0);

    var result = new Array(numberOfLevelZeroTilesX * numberOfLevelZeroTilesY);

    var index = 0;
    for (var y = 0; y < numberOfLevelZeroTilesY; ++y) {
      for (var x = 0; x < numberOfLevelZeroTilesX; ++x) {
        result[index++] = new QuadtreeTile({
          tilingScheme: tilingScheme,
          x: x,
          y: y,
          level: 0,
        });
      }
    }

    return result;
  };

  QuadtreeTile.prototype._updateCustomData = function (
    frameNumber,
    added,
    removed
  ) {
    var customData = this.customData;

    var i;
    var data;
    var rectangle;

    if (defined(added) && defined(removed)) {
      customData = customData.filter(function (value) {
        return removed.indexOf(value) === -1;
      });
      this._customData = customData;

      rectangle = this._rectangle;
      for (i = 0; i < added.length; ++i) {
        data = added[i];
        if (Rectangle.contains(rectangle, data.positionCartographic)) {
          customData.push(data);
        }
      }

      this._frameUpdated = frameNumber;
    } else {
      // interior or leaf tile, update from parent
      var parent = this._parent;
      if (defined(parent) && this._frameUpdated !== parent._frameUpdated) {
        customData.length = 0;

        rectangle = this._rectangle;
        var parentCustomData = parent.customData;
        for (i = 0; i < parentCustomData.length; ++i) {
          data = parentCustomData[i];
          if (Rectangle.contains(rectangle, data.positionCartographic)) {
            customData.push(data);
          }
        }

        this._frameUpdated = parent._frameUpdated;
      }
    }
  };

  Object.defineProperties(QuadtreeTile.prototype, {
    /**
     * Gets the tiling scheme used to tile the surface.
     * @memberof QuadtreeTile.prototype
     * @type {TilingScheme}
     */
    tilingScheme: {
      get: function () {
        return this._tilingScheme;
      },
    },

    /**
     * Gets the tile X coordinate.
     * @memberof QuadtreeTile.prototype
     * @type {Number}
     */
    x: {
      get: function () {
        return this._x;
      },
    },

    /**
     * Gets the tile Y coordinate.
     * @memberof QuadtreeTile.prototype
     * @type {Number}
     */
    y: {
      get: function () {
        return this._y;
      },
    },

    /**
     * Gets the level-of-detail, where zero is the coarsest, least-detailed.
     * @memberof QuadtreeTile.prototype
     * @type {Number}
     */
    level: {
      get: function () {
        return this._level;
      },
    },

    /**
     * Gets the parent tile of this tile.
     * @memberof QuadtreeTile.prototype
     * @type {QuadtreeTile}
     */
    parent: {
      get: function () {
        return this._parent;
      },
    },

    /**
     * Gets the cartographic rectangle of the tile, with north, south, east and
     * west properties in radians.
     * @memberof QuadtreeTile.prototype
     * @type {Rectangle}
     */
    rectangle: {
      get: function () {
        return this._rectangle;
      },
    },

    /**
     * An array of tiles that is at the next level of the tile tree.
     * @memberof QuadtreeTile.prototype
     * @type {QuadtreeTile[]}
     */
    children: {
      get: function () {
        return [
          this.northwestChild,
          this.northeastChild,
          this.southwestChild,
          this.southeastChild,
        ];
      },
    },

    /**
     * Gets the southwest child tile.
     * @memberof QuadtreeTile.prototype
     * @type {QuadtreeTile}
     */
    southwestChild: {
      get: function () {
        if (!defined(this._southwestChild)) {
          this._southwestChild = new QuadtreeTile({
            tilingScheme: this.tilingScheme,
            x: this.x * 2,
            y: this.y * 2 + 1,
            level: this.level + 1,
            parent: this,
          });
        }
        return this._southwestChild;
      },
    },

    /**
     * Gets the southeast child tile.
     * @memberof QuadtreeTile.prototype
     * @type {QuadtreeTile}
     */
    southeastChild: {
      get: function () {
        if (!defined(this._southeastChild)) {
          this._southeastChild = new QuadtreeTile({
            tilingScheme: this.tilingScheme,
            x: this.x * 2 + 1,
            y: this.y * 2 + 1,
            level: this.level + 1,
            parent: this,
          });
        }
        return this._southeastChild;
      },
    },

    /**
     * Gets the northwest child tile.
     * @memberof QuadtreeTile.prototype
     * @type {QuadtreeTile}
     */
    northwestChild: {
      get: function () {
        if (!defined(this._northwestChild)) {
          this._northwestChild = new QuadtreeTile({
            tilingScheme: this.tilingScheme,
            x: this.x * 2,
            y: this.y * 2,
            level: this.level + 1,
            parent: this,
          });
        }
        return this._northwestChild;
      },
    },

    /**
     * Gets the northeast child tile.
     * @memberof QuadtreeTile.prototype
     * @type {QuadtreeTile}
     */
    northeastChild: {
      get: function () {
        if (!defined(this._northeastChild)) {
          this._northeastChild = new QuadtreeTile({
            tilingScheme: this.tilingScheme,
            x: this.x * 2 + 1,
            y: this.y * 2,
            level: this.level + 1,
            parent: this,
          });
        }
        return this._northeastChild;
      },
    },

    /**
     * An array of objects associated with this tile.
     * @memberof QuadtreeTile.prototype
     * @type {Array}
     */
    customData: {
      get: function () {
        return this._customData;
      },
    },

    /**
     * Gets a value indicating whether or not this tile needs further loading.
     * This property will return true if the {@link QuadtreeTile#state} is
     * <code>START</code> or <code>LOADING</code>.
     * @memberof QuadtreeTile.prototype
     * @type {Boolean}
     */
    needsLoading: {
      get: function () {
        return this.state < QuadtreeTileLoadState$1.DONE;
      },
    },

    /**
     * Gets a value indicating whether or not this tile is eligible to be unloaded.
     * Typically, a tile is ineligible to be unloaded while an asynchronous operation,
     * such as a request for data, is in progress on it.  A tile will never be
     * unloaded while it is needed for rendering, regardless of the value of this
     * property.  If {@link QuadtreeTile#data} is defined and has an
     * <code>eligibleForUnloading</code> property, the value of that property is returned.
     * Otherwise, this property returns true.
     * @memberof QuadtreeTile.prototype
     * @type {Boolean}
     */
    eligibleForUnloading: {
      get: function () {
        var result = true;

        if (defined(this.data)) {
          result = this.data.eligibleForUnloading;
          if (!defined(result)) {
            result = true;
          }
        }

        return result;
      },
    },
  });

  QuadtreeTile.prototype.findLevelZeroTile = function (levelZeroTiles, x, y) {
    var xTiles = this.tilingScheme.getNumberOfXTilesAtLevel(0);
    if (x < 0) {
      x += xTiles;
    } else if (x >= xTiles) {
      x -= xTiles;
    }

    if (y < 0 || y >= this.tilingScheme.getNumberOfYTilesAtLevel(0)) {
      return undefined;
    }

    return levelZeroTiles.filter(function (tile) {
      return tile.x === x && tile.y === y;
    })[0];
  };

  QuadtreeTile.prototype.findTileToWest = function (levelZeroTiles) {
    var parent = this.parent;
    if (parent === undefined) {
      return this.findLevelZeroTile(levelZeroTiles, this.x - 1, this.y);
    }

    if (parent.southeastChild === this) {
      return parent.southwestChild;
    } else if (parent.northeastChild === this) {
      return parent.northwestChild;
    }

    var westOfParent = parent.findTileToWest(levelZeroTiles);
    if (westOfParent === undefined) {
      return undefined;
    } else if (parent.southwestChild === this) {
      return westOfParent.southeastChild;
    }
    return westOfParent.northeastChild;
  };

  QuadtreeTile.prototype.findTileToEast = function (levelZeroTiles) {
    var parent = this.parent;
    if (parent === undefined) {
      return this.findLevelZeroTile(levelZeroTiles, this.x + 1, this.y);
    }

    if (parent.southwestChild === this) {
      return parent.southeastChild;
    } else if (parent.northwestChild === this) {
      return parent.northeastChild;
    }

    var eastOfParent = parent.findTileToEast(levelZeroTiles);
    if (eastOfParent === undefined) {
      return undefined;
    } else if (parent.southeastChild === this) {
      return eastOfParent.southwestChild;
    }
    return eastOfParent.northwestChild;
  };

  QuadtreeTile.prototype.findTileToSouth = function (levelZeroTiles) {
    var parent = this.parent;
    if (parent === undefined) {
      return this.findLevelZeroTile(levelZeroTiles, this.x, this.y + 1);
    }

    if (parent.northwestChild === this) {
      return parent.southwestChild;
    } else if (parent.northeastChild === this) {
      return parent.southeastChild;
    }

    var southOfParent = parent.findTileToSouth(levelZeroTiles);
    if (southOfParent === undefined) {
      return undefined;
    } else if (parent.southwestChild === this) {
      return southOfParent.northwestChild;
    }
    return southOfParent.northeastChild;
  };

  QuadtreeTile.prototype.findTileToNorth = function (levelZeroTiles) {
    var parent = this.parent;
    if (parent === undefined) {
      return this.findLevelZeroTile(levelZeroTiles, this.x, this.y - 1);
    }

    if (parent.southwestChild === this) {
      return parent.northwestChild;
    } else if (parent.southeastChild === this) {
      return parent.northeastChild;
    }

    var northOfParent = parent.findTileToNorth(levelZeroTiles);
    if (northOfParent === undefined) {
      return undefined;
    } else if (parent.northwestChild === this) {
      return northOfParent.southwestChild;
    }
    return northOfParent.southeastChild;
  };

  /**
   * Frees the resources associated with this tile and returns it to the <code>START</code>
   * {@link QuadtreeTileLoadState}.  If the {@link QuadtreeTile#data} property is defined and it
   * has a <code>freeResources</code> method, the method will be invoked.
   *
   * @memberof QuadtreeTile
   */
  QuadtreeTile.prototype.freeResources = function () {
    this.state = QuadtreeTileLoadState$1.START;
    this.renderable = false;
    this.upsampledFromParent = false;

    if (defined(this.data) && defined(this.data.freeResources)) {
      this.data.freeResources();
    }

    freeTile(this._southwestChild);
    this._southwestChild = undefined;
    freeTile(this._southeastChild);
    this._southeastChild = undefined;
    freeTile(this._northwestChild);
    this._northwestChild = undefined;
    freeTile(this._northeastChild);
    this._northeastChild = undefined;
  };

  function freeTile(tile) {
    if (defined(tile)) {
      tile.freeResources();
    }
  }

  /**
   * A priority queue of tiles to be replaced, if necessary, to make room for new tiles.  The queue
   * is implemented as a linked list.
   *
   * @alias TileReplacementQueue
   * @private
   */
  function TileReplacementQueue() {
    this.head = undefined;
    this.tail = undefined;
    this.count = 0;
    this._lastBeforeStartOfFrame = undefined;
  }

  /**
   * Marks the start of the render frame.  Tiles before (closer to the head) this tile in the
   * list were used last frame and must not be unloaded.
   */
  TileReplacementQueue.prototype.markStartOfRenderFrame = function () {
    this._lastBeforeStartOfFrame = this.head;
  };

  /**
   * Reduces the size of the queue to a specified size by unloading the least-recently used
   * tiles.  Tiles that were used last frame will not be unloaded, even if that puts the number
   * of tiles above the specified maximum.
   *
   * @param {Number} maximumTiles The maximum number of tiles in the queue.
   */
  TileReplacementQueue.prototype.trimTiles = function (maximumTiles) {
    var tileToTrim = this.tail;
    var keepTrimming = true;
    while (
      keepTrimming &&
      defined(this._lastBeforeStartOfFrame) &&
      this.count > maximumTiles &&
      defined(tileToTrim)
    ) {
      // Stop trimming after we process the last tile not used in the
      // current frame.
      keepTrimming = tileToTrim !== this._lastBeforeStartOfFrame;

      var previous = tileToTrim.replacementPrevious;

      if (tileToTrim.eligibleForUnloading) {
        tileToTrim.freeResources();
        remove$1(this, tileToTrim);
      }

      tileToTrim = previous;
    }
  };

  function remove$1(tileReplacementQueue, item) {
    var previous = item.replacementPrevious;
    var next = item.replacementNext;

    if (item === tileReplacementQueue._lastBeforeStartOfFrame) {
      tileReplacementQueue._lastBeforeStartOfFrame = next;
    }

    if (item === tileReplacementQueue.head) {
      tileReplacementQueue.head = next;
    } else {
      previous.replacementNext = next;
    }

    if (item === tileReplacementQueue.tail) {
      tileReplacementQueue.tail = previous;
    } else {
      next.replacementPrevious = previous;
    }

    item.replacementPrevious = undefined;
    item.replacementNext = undefined;

    --tileReplacementQueue.count;
  }

  /**
   * Marks a tile as rendered this frame and moves it before the first tile that was not rendered
   * this frame.
   *
   * @param {TileReplacementQueue} item The tile that was rendered.
   */
  TileReplacementQueue.prototype.markTileRendered = function (item) {
    var head = this.head;
    if (head === item) {
      if (item === this._lastBeforeStartOfFrame) {
        this._lastBeforeStartOfFrame = item.replacementNext;
      }
      return;
    }

    ++this.count;

    if (!defined(head)) {
      // no other tiles in the list
      item.replacementPrevious = undefined;
      item.replacementNext = undefined;
      this.head = item;
      this.tail = item;
      return;
    }

    if (defined(item.replacementPrevious) || defined(item.replacementNext)) {
      // tile already in the list, remove from its current location
      remove$1(this, item);
    }

    item.replacementPrevious = undefined;
    item.replacementNext = head;
    head.replacementPrevious = item;

    this.head = item;
  };

  /**
   * Renders massive sets of data by utilizing level-of-detail and culling.  The globe surface is divided into
   * a quadtree of tiles with large, low-detail tiles at the root and small, high-detail tiles at the leaves.
   * The set of tiles to render is selected by projecting an estimate of the geometric error in a tile onto
   * the screen to estimate screen-space error, in pixels, which must be below a user-specified threshold.
   * The actual content of the tiles is arbitrary and is specified using a {@link QuadtreeTileProvider}.
   *
   * @alias QuadtreePrimitive
   * @constructor
   * @private
   *
   * @param {QuadtreeTileProvider} options.tileProvider The tile provider that loads, renders, and estimates
   *        the distance to individual tiles.
   * @param {Number} [options.maximumScreenSpaceError=2] The maximum screen-space error, in pixels, that is allowed.
   *        A higher maximum error will render fewer tiles and improve performance, while a lower
   *        value will improve visual quality.
   * @param {Number} [options.tileCacheSize=100] The maximum number of tiles that will be retained in the tile cache.
   *        Note that tiles will never be unloaded if they were used for rendering the last
   *        frame, so the actual number of resident tiles may be higher.  The value of
   *        this property will not affect visual quality.
   */
  function QuadtreePrimitive(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.tileProvider)) {
      throw new DeveloperError("options.tileProvider is required.");
    }
    if (defined(options.tileProvider.quadtree)) {
      throw new DeveloperError(
        "A QuadtreeTileProvider can only be used with a single QuadtreePrimitive"
      );
    }
    //>>includeEnd('debug');

    this._tileProvider = options.tileProvider;
    this._tileProvider.quadtree = this;

    this._debug = {
      enableDebugOutput: false,

      maxDepth: 0,
      maxDepthVisited: 0,
      tilesVisited: 0,
      tilesCulled: 0,
      tilesRendered: 0,
      tilesWaitingForChildren: 0,

      lastMaxDepth: -1,
      lastMaxDepthVisited: -1,
      lastTilesVisited: -1,
      lastTilesCulled: -1,
      lastTilesRendered: -1,
      lastTilesWaitingForChildren: -1,

      suspendLodUpdate: false,
    };

    var tilingScheme = this._tileProvider.tilingScheme;
    var ellipsoid = tilingScheme.ellipsoid;

    this._tilesToRender = [];
    this._tileLoadQueueHigh = []; // high priority tiles are preventing refinement
    this._tileLoadQueueMedium = []; // medium priority tiles are being rendered
    this._tileLoadQueueLow = []; // low priority tiles were refined past or are non-visible parts of quads.
    this._tileReplacementQueue = new TileReplacementQueue();
    this._levelZeroTiles = undefined;
    this._loadQueueTimeSlice = 5.0;
    this._tilesInvalidated = false;

    this._addHeightCallbacks = [];
    this._removeHeightCallbacks = [];

    this._tileToUpdateHeights = [];
    this._lastTileIndex = 0;
    this._updateHeightsTimeSlice = 2.0;

    // If a culled tile contains _cameraPositionCartographic or _cameraReferenceFrameOriginCartographic, it will be marked
    // TileSelectionResult.CULLED_BUT_NEEDED and added to the list of tiles to update heights,
    // even though it is not rendered.
    // These are updated each frame in `selectTilesForRendering`.
    this._cameraPositionCartographic = undefined;
    this._cameraReferenceFrameOriginCartographic = undefined;

    /**
     * Gets or sets the maximum screen-space error, in pixels, that is allowed.
     * A higher maximum error will render fewer tiles and improve performance, while a lower
     * value will improve visual quality.
     * @type {Number}
     * @default 2
     */
    this.maximumScreenSpaceError = defaultValue(
      options.maximumScreenSpaceError,
      2
    );

    /**
     * Gets or sets the maximum number of tiles that will be retained in the tile cache.
     * Note that tiles will never be unloaded if they were used for rendering the last
     * frame, so the actual number of resident tiles may be higher.  The value of
     * this property will not affect visual quality.
     * @type {Number}
     * @default 100
     */
    this.tileCacheSize = defaultValue(options.tileCacheSize, 100);

    /**
     * Gets or sets the number of loading descendant tiles that is considered "too many".
     * If a tile has too many loading descendants, that tile will be loaded and rendered before any of
     * its descendants are loaded and rendered. This means more feedback for the user that something
     * is happening at the cost of a longer overall load time. Setting this to 0 will cause each
     * tile level to be loaded successively, significantly increasing load time. Setting it to a large
     * number (e.g. 1000) will minimize the number of tiles that are loaded but tend to make
     * detail appear all at once after a long wait.
     * @type {Number}
     * @default 20
     */
    this.loadingDescendantLimit = 20;

    /**
     * Gets or sets a value indicating whether the ancestors of rendered tiles should be preloaded.
     * Setting this to true optimizes the zoom-out experience and provides more detail in
     * newly-exposed areas when panning. The down side is that it requires loading more tiles.
     * @type {Boolean}
     * @default true
     */
    this.preloadAncestors = true;

    /**
     * Gets or sets a value indicating whether the siblings of rendered tiles should be preloaded.
     * Setting this to true causes tiles with the same parent as a rendered tile to be loaded, even
     * if they are culled. Setting this to true may provide a better panning experience at the
     * cost of loading more tiles.
     * @type {Boolean}
     * @default false
     */
    this.preloadSiblings = false;

    this._occluders = new QuadtreeOccluders({
      ellipsoid: ellipsoid,
    });

    this._tileLoadProgressEvent = new Event();
    this._lastTileLoadQueueLength = 0;

    this._lastSelectionFrameNumber = undefined;
  }

  Object.defineProperties(QuadtreePrimitive.prototype, {
    /**
     * Gets the provider of {@link QuadtreeTile} instances for this quadtree.
     * @type {QuadtreeTile}
     * @memberof QuadtreePrimitive.prototype
     */
    tileProvider: {
      get: function () {
        return this._tileProvider;
      },
    },
    /**
     * Gets an event that's raised when the length of the tile load queue has changed since the last render frame.  When the load queue is empty,
     * all terrain and imagery for the current view have been loaded.  The event passes the new length of the tile load queue.
     *
     * @memberof QuadtreePrimitive.prototype
     * @type {Event}
     */
    tileLoadProgressEvent: {
      get: function () {
        return this._tileLoadProgressEvent;
      },
    },

    occluders: {
      get: function () {
        return this._occluders;
      },
    },
  });

  /**
   * Invalidates and frees all the tiles in the quadtree.  The tiles must be reloaded
   * before they can be displayed.
   *
   * @memberof QuadtreePrimitive
   */
  QuadtreePrimitive.prototype.invalidateAllTiles = function () {
    this._tilesInvalidated = true;
  };

  function invalidateAllTiles(primitive) {
    // Clear the replacement queue
    var replacementQueue = primitive._tileReplacementQueue;
    replacementQueue.head = undefined;
    replacementQueue.tail = undefined;
    replacementQueue.count = 0;

    clearTileLoadQueue(primitive);

    // Free and recreate the level zero tiles.
    var levelZeroTiles = primitive._levelZeroTiles;
    if (defined(levelZeroTiles)) {
      for (var i = 0; i < levelZeroTiles.length; ++i) {
        var tile = levelZeroTiles[i];
        var customData = tile.customData;
        var customDataLength = customData.length;

        for (var j = 0; j < customDataLength; ++j) {
          var data = customData[j];
          data.level = 0;
          primitive._addHeightCallbacks.push(data);
        }

        levelZeroTiles[i].freeResources();
      }
    }

    primitive._levelZeroTiles = undefined;

    primitive._tileProvider.cancelReprojections();
  }

  /**
   * Invokes a specified function for each {@link QuadtreeTile} that is partially
   * or completely loaded.
   *
   * @param {Function} tileFunction The function to invoke for each loaded tile.  The
   *        function is passed a reference to the tile as its only parameter.
   */
  QuadtreePrimitive.prototype.forEachLoadedTile = function (tileFunction) {
    var tile = this._tileReplacementQueue.head;
    while (defined(tile)) {
      if (tile.state !== QuadtreeTileLoadState$1.START) {
        tileFunction(tile);
      }
      tile = tile.replacementNext;
    }
  };

  /**
   * Invokes a specified function for each {@link QuadtreeTile} that was rendered
   * in the most recent frame.
   *
   * @param {Function} tileFunction The function to invoke for each rendered tile.  The
   *        function is passed a reference to the tile as its only parameter.
   */
  QuadtreePrimitive.prototype.forEachRenderedTile = function (tileFunction) {
    var tilesRendered = this._tilesToRender;
    for (var i = 0, len = tilesRendered.length; i < len; ++i) {
      tileFunction(tilesRendered[i]);
    }
  };

  /**
   * Calls the callback when a new tile is rendered that contains the given cartographic. The only parameter
   * is the cartesian position on the tile.
   *
   * @param {Cartographic} cartographic The cartographic position.
   * @param {Function} callback The function to be called when a new tile is loaded containing cartographic.
   * @returns {Function} The function to remove this callback from the quadtree.
   */
  QuadtreePrimitive.prototype.updateHeight = function (cartographic, callback) {
    var primitive = this;
    var object = {
      positionOnEllipsoidSurface: undefined,
      positionCartographic: cartographic,
      level: -1,
      callback: callback,
    };

    object.removeFunc = function () {
      var addedCallbacks = primitive._addHeightCallbacks;
      var length = addedCallbacks.length;
      for (var i = 0; i < length; ++i) {
        if (addedCallbacks[i] === object) {
          addedCallbacks.splice(i, 1);
          break;
        }
      }
      primitive._removeHeightCallbacks.push(object);
    };

    primitive._addHeightCallbacks.push(object);
    return object.removeFunc;
  };

  /**
   * Updates the tile provider imagery and continues to process the tile load queue.
   * @private
   */
  QuadtreePrimitive.prototype.update = function (frameState) {
    if (defined(this._tileProvider.update)) {
      this._tileProvider.update(frameState);
    }
  };

  function clearTileLoadQueue(primitive) {
    var debug = primitive._debug;
    debug.maxDepth = 0;
    debug.maxDepthVisited = 0;
    debug.tilesVisited = 0;
    debug.tilesCulled = 0;
    debug.tilesRendered = 0;
    debug.tilesWaitingForChildren = 0;

    primitive._tileLoadQueueHigh.length = 0;
    primitive._tileLoadQueueMedium.length = 0;
    primitive._tileLoadQueueLow.length = 0;
  }

  /**
   * Initializes values for a new render frame and prepare the tile load queue.
   * @private
   */
  QuadtreePrimitive.prototype.beginFrame = function (frameState) {
    var passes = frameState.passes;
    if (!passes.render) {
      return;
    }

    if (this._tilesInvalidated) {
      invalidateAllTiles(this);
      this._tilesInvalidated = false;
    }

    // Gets commands for any texture re-projections
    this._tileProvider.initialize(frameState);

    clearTileLoadQueue(this);

    if (this._debug.suspendLodUpdate) {
      return;
    }

    this._tileReplacementQueue.markStartOfRenderFrame();
  };

  /**
   * Selects new tiles to load based on the frame state and creates render commands.
   * @private
   */
  QuadtreePrimitive.prototype.render = function (frameState) {
    var passes = frameState.passes;
    var tileProvider = this._tileProvider;

    if (passes.render) {
      tileProvider.beginUpdate(frameState);

      selectTilesForRendering(this, frameState);
      createRenderCommandsForSelectedTiles(this, frameState);

      tileProvider.endUpdate(frameState);
    }

    if (passes.pick && this._tilesToRender.length > 0) {
      tileProvider.updateForPick(frameState);
    }
  };

  /**
   * Checks if the load queue length has changed since the last time we raised a queue change event - if so, raises
   * a new change event at the end of the render cycle.
   * @private
   */
  function updateTileLoadProgress(primitive, frameState) {
    var currentLoadQueueLength =
      primitive._tileLoadQueueHigh.length +
      primitive._tileLoadQueueMedium.length +
      primitive._tileLoadQueueLow.length;

    if (
      currentLoadQueueLength !== primitive._lastTileLoadQueueLength ||
      primitive._tilesInvalidated
    ) {
      frameState.afterRender.push(
        Event.prototype.raiseEvent.bind(
          primitive._tileLoadProgressEvent,
          currentLoadQueueLength
        )
      );
      primitive._lastTileLoadQueueLength = currentLoadQueueLength;
    }

    var debug = primitive._debug;
    if (debug.enableDebugOutput && !debug.suspendLodUpdate) {
      debug.maxDepth = primitive._tilesToRender.reduce(function (max, tile) {
        return Math.max(max, tile.level);
      }, -1);
      debug.tilesRendered = primitive._tilesToRender.length;

      if (
        debug.tilesVisited !== debug.lastTilesVisited ||
        debug.tilesRendered !== debug.lastTilesRendered ||
        debug.tilesCulled !== debug.lastTilesCulled ||
        debug.maxDepth !== debug.lastMaxDepth ||
        debug.tilesWaitingForChildren !== debug.lastTilesWaitingForChildren ||
        debug.maxDepthVisited !== debug.lastMaxDepthVisited
      ) {
        console.log(
          "Visited " +
            debug.tilesVisited +
            ", Rendered: " +
            debug.tilesRendered +
            ", Culled: " +
            debug.tilesCulled +
            ", Max Depth Rendered: " +
            debug.maxDepth +
            ", Max Depth Visited: " +
            debug.maxDepthVisited +
            ", Waiting for children: " +
            debug.tilesWaitingForChildren
        );

        debug.lastTilesVisited = debug.tilesVisited;
        debug.lastTilesRendered = debug.tilesRendered;
        debug.lastTilesCulled = debug.tilesCulled;
        debug.lastMaxDepth = debug.maxDepth;
        debug.lastTilesWaitingForChildren = debug.tilesWaitingForChildren;
        debug.lastMaxDepthVisited = debug.maxDepthVisited;
      }
    }
  }

  /**
   * Updates terrain heights.
   * @private
   */
  QuadtreePrimitive.prototype.endFrame = function (frameState) {
    var passes = frameState.passes;
    if (!passes.render || frameState.mode === SceneMode$1.MORPHING) {
      // Only process the load queue for a single pass.
      // Don't process the load queue or update heights during the morph flights.
      return;
    }

    // Load/create resources for terrain and imagery. Prepare texture re-projections for the next frame.
    processTileLoadQueue(this, frameState);
    updateHeights(this, frameState);
    updateTileLoadProgress(this, frameState);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @memberof QuadtreePrimitive
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see QuadtreePrimitive#destroy
   */
  QuadtreePrimitive.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @memberof QuadtreePrimitive
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * primitive = primitive && primitive.destroy();
   *
   * @see QuadtreePrimitive#isDestroyed
   */
  QuadtreePrimitive.prototype.destroy = function () {
    this._tileProvider = this._tileProvider && this._tileProvider.destroy();
  };

  var comparisonPoint;
  var centerScratch$5 = new Cartographic();
  function compareDistanceToPoint(a, b) {
    var center = Rectangle.center(a.rectangle, centerScratch$5);
    var alon = center.longitude - comparisonPoint.longitude;
    var alat = center.latitude - comparisonPoint.latitude;

    center = Rectangle.center(b.rectangle, centerScratch$5);
    var blon = center.longitude - comparisonPoint.longitude;
    var blat = center.latitude - comparisonPoint.latitude;

    return alon * alon + alat * alat - (blon * blon + blat * blat);
  }

  var cameraOriginScratch = new Cartesian3();
  var rootTraversalDetails = [];

  function selectTilesForRendering(primitive, frameState) {
    var debug = primitive._debug;
    if (debug.suspendLodUpdate) {
      return;
    }

    // Clear the render list.
    var tilesToRender = primitive._tilesToRender;
    tilesToRender.length = 0;

    // We can't render anything before the level zero tiles exist.
    var i;
    var tileProvider = primitive._tileProvider;
    if (!defined(primitive._levelZeroTiles)) {
      if (tileProvider.ready) {
        var tilingScheme = tileProvider.tilingScheme;
        primitive._levelZeroTiles = QuadtreeTile.createLevelZeroTiles(
          tilingScheme
        );
        var numberOfRootTiles = primitive._levelZeroTiles.length;
        if (rootTraversalDetails.length < numberOfRootTiles) {
          rootTraversalDetails = new Array(numberOfRootTiles);
          for (i = 0; i < numberOfRootTiles; ++i) {
            if (rootTraversalDetails[i] === undefined) {
              rootTraversalDetails[i] = new TraversalDetails();
            }
          }
        }
      } else {
        // Nothing to do until the provider is ready.
        return;
      }
    }

    primitive._occluders.ellipsoid.cameraPosition = frameState.camera.positionWC;

    var tile;
    var levelZeroTiles = primitive._levelZeroTiles;
    var occluders = levelZeroTiles.length > 1 ? primitive._occluders : undefined;

    // Sort the level zero tiles by the distance from the center to the camera.
    // The level zero tiles aren't necessarily a nice neat quad, so we can't use the
    // quadtree ordering we use elsewhere in the tree
    comparisonPoint = frameState.camera.positionCartographic;
    levelZeroTiles.sort(compareDistanceToPoint);

    var customDataAdded = primitive._addHeightCallbacks;
    var customDataRemoved = primitive._removeHeightCallbacks;
    var frameNumber = frameState.frameNumber;

    var len;
    if (customDataAdded.length > 0 || customDataRemoved.length > 0) {
      for (i = 0, len = levelZeroTiles.length; i < len; ++i) {
        tile = levelZeroTiles[i];
        tile._updateCustomData(frameNumber, customDataAdded, customDataRemoved);
      }

      customDataAdded.length = 0;
      customDataRemoved.length = 0;
    }

    var camera = frameState.camera;

    primitive._cameraPositionCartographic = camera.positionCartographic;
    var cameraFrameOrigin = Matrix4.getTranslation(
      camera.transform,
      cameraOriginScratch
    );
    primitive._cameraReferenceFrameOriginCartographic = primitive.tileProvider.tilingScheme.ellipsoid.cartesianToCartographic(
      cameraFrameOrigin,
      primitive._cameraReferenceFrameOriginCartographic
    );

    // Traverse in depth-first, near-to-far order.
    for (i = 0, len = levelZeroTiles.length; i < len; ++i) {
      tile = levelZeroTiles[i];
      primitive._tileReplacementQueue.markTileRendered(tile);
      if (!tile.renderable) {
        queueTileLoad(primitive, primitive._tileLoadQueueHigh, tile, frameState);
        ++debug.tilesWaitingForChildren;
      } else {
        visitIfVisible(
          primitive,
          tile,
          tileProvider,
          frameState,
          occluders,
          false,
          rootTraversalDetails[i]
        );
      }
    }

    primitive._lastSelectionFrameNumber = frameNumber;
  }

  function queueTileLoad(primitive, queue, tile, frameState) {
    if (!tile.needsLoading) {
      return;
    }

    if (primitive.tileProvider.computeTileLoadPriority !== undefined) {
      tile._loadPriority = primitive.tileProvider.computeTileLoadPriority(
        tile,
        frameState
      );
    }
    queue.push(tile);
  }

  /**
   * Tracks details of traversing a tile while selecting tiles for rendering.
   * @alias TraversalDetails
   * @constructor
   * @private
   */
  function TraversalDetails() {
    /**
     * True if all selected (i.e. not culled or refined) tiles in this tile's subtree
     * are renderable. If the subtree is renderable, we'll render it; no drama.
     */
    this.allAreRenderable = true;

    /**
     * True if any tiles in this tile's subtree were rendered last frame. If any
     * were, we must render the subtree rather than this tile, because rendering
     * this tile would cause detail to vanish that was visible last frame, and
     * that's no good.
     */
    this.anyWereRenderedLastFrame = false;

    /**
     * Counts the number of selected tiles in this tile's subtree that are
     * not yet ready to be rendered because they need more loading. Note that
     * this value will _not_ necessarily be zero when
     * {@link TraversalDetails#allAreRenderable} is true, for subtle reasons.
     * When {@link TraversalDetails#allAreRenderable} and
     * {@link TraversalDetails#anyWereRenderedLastFrame} are both false, we
     * will render this tile instead of any tiles in its subtree and
     * the `allAreRenderable` value for this tile will reflect only whether _this_
     * tile is renderable. The `notYetRenderableCount` value, however, will still
     * reflect the total number of tiles that we are waiting on, including the
     * ones that we're not rendering. `notYetRenderableCount` is only reset
     * when a subtree is removed from the render queue because the
     * `notYetRenderableCount` exceeds the
     * {@link QuadtreePrimitive#loadingDescendantLimit}.
     */
    this.notYetRenderableCount = 0;
  }

  function TraversalQuadDetails() {
    this.southwest = new TraversalDetails();
    this.southeast = new TraversalDetails();
    this.northwest = new TraversalDetails();
    this.northeast = new TraversalDetails();
  }

  TraversalQuadDetails.prototype.combine = function (result) {
    var southwest = this.southwest;
    var southeast = this.southeast;
    var northwest = this.northwest;
    var northeast = this.northeast;

    result.allAreRenderable =
      southwest.allAreRenderable &&
      southeast.allAreRenderable &&
      northwest.allAreRenderable &&
      northeast.allAreRenderable;
    result.anyWereRenderedLastFrame =
      southwest.anyWereRenderedLastFrame ||
      southeast.anyWereRenderedLastFrame ||
      northwest.anyWereRenderedLastFrame ||
      northeast.anyWereRenderedLastFrame;
    result.notYetRenderableCount =
      southwest.notYetRenderableCount +
      southeast.notYetRenderableCount +
      northwest.notYetRenderableCount +
      northeast.notYetRenderableCount;
  };

  var traversalQuadsByLevel = new Array(31); // level 30 tiles are ~2cm wide at the equator, should be good enough.
  for (var i$4 = 0; i$4 < traversalQuadsByLevel.length; ++i$4) {
    traversalQuadsByLevel[i$4] = new TraversalQuadDetails();
  }

  /**
   * Visits a tile for possible rendering. When we call this function with a tile:
   *
   *    * the tile has been determined to be visible (possibly based on a bounding volume that is not very tight-fitting)
   *    * its parent tile does _not_ meet the SSE (unless ancestorMeetsSse=true, see comments below)
   *    * the tile may or may not be renderable
   *
   * @private
   *
   * @param {Primitive} primitive The QuadtreePrimitive.
   * @param {FrameState} frameState The frame state.
   * @param {QuadtreeTile} tile The tile to visit
   * @param {Boolean} ancestorMeetsSse True if a tile higher in the tile tree already met the SSE and we're refining further only
   *                  to maintain detail while that higher tile loads.
   * @param {TraversalDetails} traveralDetails On return, populated with details of how the traversal of this tile went.
   */
  function visitTile$3(
    primitive,
    frameState,
    tile,
    ancestorMeetsSse,
    traversalDetails
  ) {
    var debug = primitive._debug;

    ++debug.tilesVisited;

    primitive._tileReplacementQueue.markTileRendered(tile);
    tile._updateCustomData(frameState.frameNumber);

    if (tile.level > debug.maxDepthVisited) {
      debug.maxDepthVisited = tile.level;
    }

    var meetsSse =
      screenSpaceError(primitive, frameState, tile) <
      primitive.maximumScreenSpaceError;

    var southwestChild = tile.southwestChild;
    var southeastChild = tile.southeastChild;
    var northwestChild = tile.northwestChild;
    var northeastChild = tile.northeastChild;

    var lastFrame = primitive._lastSelectionFrameNumber;
    var lastFrameSelectionResult =
      tile._lastSelectionResultFrame === lastFrame
        ? tile._lastSelectionResult
        : TileSelectionResult.NONE;

    var tileProvider = primitive.tileProvider;

    if (meetsSse || ancestorMeetsSse) {
      // This tile (or an ancestor) is the one we want to render this frame, but we'll do different things depending
      // on the state of this tile and on what we did _last_ frame.

      // We can render it if _any_ of the following are true:
      // 1. We rendered it (or kicked it) last frame.
      // 2. This tile was culled last frame, or it wasn't even visited because an ancestor was culled.
      // 3. The tile is completely done loading.
      // 4. a) Terrain is ready, and
      //    b) All necessary imagery is ready. Necessary imagery is imagery that was rendered with this tile
      //       or any descendants last frame. Such imagery is required because rendering this tile without
      //       it would cause detail to disappear.
      //
      // Determining condition 4 is more expensive, so we check the others first.
      //
      // Note that even if we decide to render a tile here, it may later get "kicked" in favor of an ancestor.

      var oneRenderedLastFrame =
        TileSelectionResult.originalResult(lastFrameSelectionResult) ===
        TileSelectionResult.RENDERED;
      var twoCulledOrNotVisited =
        TileSelectionResult.originalResult(lastFrameSelectionResult) ===
          TileSelectionResult.CULLED ||
        lastFrameSelectionResult === TileSelectionResult.NONE;
      var threeCompletelyLoaded = tile.state === QuadtreeTileLoadState$1.DONE;

      var renderable =
        oneRenderedLastFrame || twoCulledOrNotVisited || threeCompletelyLoaded;

      if (!renderable) {
        // Check the more expensive condition 4 above. This requires details of the thing
        // we're rendering (e.g. the globe surface), so delegate it to the tile provider.
        if (defined(tileProvider.canRenderWithoutLosingDetail)) {
          renderable = tileProvider.canRenderWithoutLosingDetail(tile);
        }
      }

      if (renderable) {
        // Only load this tile if it (not just an ancestor) meets the SSE.
        if (meetsSse) {
          queueTileLoad(
            primitive,
            primitive._tileLoadQueueMedium,
            tile,
            frameState
          );
        }
        addTileToRenderList(primitive, tile);

        traversalDetails.allAreRenderable = tile.renderable;
        traversalDetails.anyWereRenderedLastFrame =
          lastFrameSelectionResult === TileSelectionResult.RENDERED;
        traversalDetails.notYetRenderableCount = tile.renderable ? 0 : 1;

        tile._lastSelectionResultFrame = frameState.frameNumber;
        tile._lastSelectionResult = TileSelectionResult.RENDERED;

        if (!traversalDetails.anyWereRenderedLastFrame) {
          // Tile is newly-rendered this frame, so update its heights.
          primitive._tileToUpdateHeights.push(tile);
        }

        return;
      }

      // Otherwise, we can't render this tile (or its fill) because doing so would cause detail to disappear
      // that was visible last frame. Instead, keep rendering any still-visible descendants that were rendered
      // last frame and render fills for newly-visible descendants. E.g. if we were rendering level 15 last
      // frame but this frame we want level 14 and the closest renderable level <= 14 is 0, rendering level
      // zero would be pretty jarring so instead we keep rendering level 15 even though its SSE is better
      // than required. So fall through to continue traversal...
      ancestorMeetsSse = true;

      // Load this blocker tile with high priority, but only if this tile (not just an ancestor) meets the SSE.
      if (meetsSse) {
        queueTileLoad(primitive, primitive._tileLoadQueueHigh, tile, frameState);
      }
    }

    if (tileProvider.canRefine(tile)) {
      var allAreUpsampled =
        southwestChild.upsampledFromParent &&
        southeastChild.upsampledFromParent &&
        northwestChild.upsampledFromParent &&
        northeastChild.upsampledFromParent;

      if (allAreUpsampled) {
        // No point in rendering the children because they're all upsampled.  Render this tile instead.
        addTileToRenderList(primitive, tile);

        // Rendered tile that's not waiting on children loads with medium priority.
        queueTileLoad(
          primitive,
          primitive._tileLoadQueueMedium,
          tile,
          frameState
        );

        // Make sure we don't unload the children and forget they're upsampled.
        primitive._tileReplacementQueue.markTileRendered(southwestChild);
        primitive._tileReplacementQueue.markTileRendered(southeastChild);
        primitive._tileReplacementQueue.markTileRendered(northwestChild);
        primitive._tileReplacementQueue.markTileRendered(northeastChild);

        traversalDetails.allAreRenderable = tile.renderable;
        traversalDetails.anyWereRenderedLastFrame =
          lastFrameSelectionResult === TileSelectionResult.RENDERED;
        traversalDetails.notYetRenderableCount = tile.renderable ? 0 : 1;

        tile._lastSelectionResultFrame = frameState.frameNumber;
        tile._lastSelectionResult = TileSelectionResult.RENDERED;

        if (!traversalDetails.anyWereRenderedLastFrame) {
          // Tile is newly-rendered this frame, so update its heights.
          primitive._tileToUpdateHeights.push(tile);
        }

        return;
      }

      // SSE is not good enough, so refine.
      tile._lastSelectionResultFrame = frameState.frameNumber;
      tile._lastSelectionResult = TileSelectionResult.REFINED;

      var firstRenderedDescendantIndex = primitive._tilesToRender.length;
      var loadIndexLow = primitive._tileLoadQueueLow.length;
      var loadIndexMedium = primitive._tileLoadQueueMedium.length;
      var loadIndexHigh = primitive._tileLoadQueueHigh.length;
      var tilesToUpdateHeightsIndex = primitive._tileToUpdateHeights.length;

      // No need to add the children to the load queue because they'll be added (if necessary) when they're visited.
      visitVisibleChildrenNearToFar(
        primitive,
        southwestChild,
        southeastChild,
        northwestChild,
        northeastChild,
        frameState,
        ancestorMeetsSse,
        traversalDetails
      );

      // If no descendant tiles were added to the render list by the function above, it means they were all
      // culled even though this tile was deemed visible. That's pretty common.

      if (firstRenderedDescendantIndex !== primitive._tilesToRender.length) {
        // At least one descendant tile was added to the render list.
        // The traversalDetails tell us what happened while visiting the children.

        var allAreRenderable = traversalDetails.allAreRenderable;
        var anyWereRenderedLastFrame = traversalDetails.anyWereRenderedLastFrame;
        var notYetRenderableCount = traversalDetails.notYetRenderableCount;
        var queuedForLoad = false;

        if (!allAreRenderable && !anyWereRenderedLastFrame) {
          // Some of our descendants aren't ready to render yet, and none were rendered last frame,
          // so kick them all out of the render list and render this tile instead. Continue to load them though!

          // Mark the rendered descendants and their ancestors - up to this tile - as kicked.
          var renderList = primitive._tilesToRender;
          for (var i = firstRenderedDescendantIndex; i < renderList.length; ++i) {
            var workTile = renderList[i];
            while (
              workTile !== undefined &&
              workTile._lastSelectionResult !== TileSelectionResult.KICKED &&
              workTile !== tile
            ) {
              workTile._lastSelectionResult = TileSelectionResult.kick(
                workTile._lastSelectionResult
              );
              workTile = workTile.parent;
            }
          }

          // Remove all descendants from the render list and add this tile.
          primitive._tilesToRender.length = firstRenderedDescendantIndex;
          primitive._tileToUpdateHeights.length = tilesToUpdateHeightsIndex;
          addTileToRenderList(primitive, tile);

          tile._lastSelectionResult = TileSelectionResult.RENDERED;

          // If we're waiting on heaps of descendants, the above will take too long. So in that case,
          // load this tile INSTEAD of loading any of the descendants, and tell the up-level we're only waiting
          // on this tile. Keep doing this until we actually manage to render this tile.
          var wasRenderedLastFrame =
            lastFrameSelectionResult === TileSelectionResult.RENDERED;
          if (
            !wasRenderedLastFrame &&
            notYetRenderableCount > primitive.loadingDescendantLimit
          ) {
            // Remove all descendants from the load queues.
            primitive._tileLoadQueueLow.length = loadIndexLow;
            primitive._tileLoadQueueMedium.length = loadIndexMedium;
            primitive._tileLoadQueueHigh.length = loadIndexHigh;
            queueTileLoad(
              primitive,
              primitive._tileLoadQueueMedium,
              tile,
              frameState
            );
            traversalDetails.notYetRenderableCount = tile.renderable ? 0 : 1;
            queuedForLoad = true;
          }

          traversalDetails.allAreRenderable = tile.renderable;
          traversalDetails.anyWereRenderedLastFrame = wasRenderedLastFrame;

          if (!wasRenderedLastFrame) {
            // Tile is newly-rendered this frame, so update its heights.
            primitive._tileToUpdateHeights.push(tile);
          }

          ++debug.tilesWaitingForChildren;
        }

        if (primitive.preloadAncestors && !queuedForLoad) {
          queueTileLoad(primitive, primitive._tileLoadQueueLow, tile, frameState);
        }
      }

      return;
    }

    tile._lastSelectionResultFrame = frameState.frameNumber;
    tile._lastSelectionResult = TileSelectionResult.RENDERED;

    // We'd like to refine but can't because we have no availability data for this tile's children,
    // so we have no idea if refinining would involve a load or an upsample. We'll have to finish
    // loading this tile first in order to find that out, so load this refinement blocker with
    // high priority.
    addTileToRenderList(primitive, tile);
    queueTileLoad(primitive, primitive._tileLoadQueueHigh, tile, frameState);

    traversalDetails.allAreRenderable = tile.renderable;
    traversalDetails.anyWereRenderedLastFrame =
      lastFrameSelectionResult === TileSelectionResult.RENDERED;
    traversalDetails.notYetRenderableCount = tile.renderable ? 0 : 1;
  }

  function visitVisibleChildrenNearToFar(
    primitive,
    southwest,
    southeast,
    northwest,
    northeast,
    frameState,
    ancestorMeetsSse,
    traversalDetails
  ) {
    var cameraPosition = frameState.camera.positionCartographic;
    var tileProvider = primitive._tileProvider;
    var occluders = primitive._occluders;

    var quadDetails = traversalQuadsByLevel[southwest.level];
    var southwestDetails = quadDetails.southwest;
    var southeastDetails = quadDetails.southeast;
    var northwestDetails = quadDetails.northwest;
    var northeastDetails = quadDetails.northeast;

    if (cameraPosition.longitude < southwest.rectangle.east) {
      if (cameraPosition.latitude < southwest.rectangle.north) {
        // Camera in southwest quadrant
        visitIfVisible(
          primitive,
          southwest,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          southwestDetails
        );
        visitIfVisible(
          primitive,
          southeast,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          southeastDetails
        );
        visitIfVisible(
          primitive,
          northwest,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          northwestDetails
        );
        visitIfVisible(
          primitive,
          northeast,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          northeastDetails
        );
      } else {
        // Camera in northwest quadrant
        visitIfVisible(
          primitive,
          northwest,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          northwestDetails
        );
        visitIfVisible(
          primitive,
          southwest,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          southwestDetails
        );
        visitIfVisible(
          primitive,
          northeast,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          northeastDetails
        );
        visitIfVisible(
          primitive,
          southeast,
          tileProvider,
          frameState,
          occluders,
          ancestorMeetsSse,
          southeastDetails
        );
      }
    } else if (cameraPosition.latitude < southwest.rectangle.north) {
      // Camera southeast quadrant
      visitIfVisible(
        primitive,
        southeast,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        southeastDetails
      );
      visitIfVisible(
        primitive,
        southwest,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        southwestDetails
      );
      visitIfVisible(
        primitive,
        northeast,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        northeastDetails
      );
      visitIfVisible(
        primitive,
        northwest,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        northwestDetails
      );
    } else {
      // Camera in northeast quadrant
      visitIfVisible(
        primitive,
        northeast,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        northeastDetails
      );
      visitIfVisible(
        primitive,
        northwest,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        northwestDetails
      );
      visitIfVisible(
        primitive,
        southeast,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        southeastDetails
      );
      visitIfVisible(
        primitive,
        southwest,
        tileProvider,
        frameState,
        occluders,
        ancestorMeetsSse,
        southwestDetails
      );
    }

    quadDetails.combine(traversalDetails);
  }

  function containsNeededPosition(primitive, tile) {
    var rectangle = tile.rectangle;
    return (
      (defined(primitive._cameraPositionCartographic) &&
        Rectangle.contains(rectangle, primitive._cameraPositionCartographic)) ||
      (defined(primitive._cameraReferenceFrameOriginCartographic) &&
        Rectangle.contains(
          rectangle,
          primitive._cameraReferenceFrameOriginCartographic
        ))
    );
  }

  function visitIfVisible(
    primitive,
    tile,
    tileProvider,
    frameState,
    occluders,
    ancestorMeetsSse,
    traversalDetails
  ) {
    if (
      tileProvider.computeTileVisibility(tile, frameState, occluders) !==
      Visibility$1.NONE
    ) {
      return visitTile$3(
        primitive,
        frameState,
        tile,
        ancestorMeetsSse,
        traversalDetails
      );
    }

    ++primitive._debug.tilesCulled;
    primitive._tileReplacementQueue.markTileRendered(tile);

    traversalDetails.allAreRenderable = true;
    traversalDetails.anyWereRenderedLastFrame = false;
    traversalDetails.notYetRenderableCount = 0;

    if (containsNeededPosition(primitive, tile)) {
      // Load the tile(s) that contains the camera's position and
      // the origin of its reference frame with medium priority.
      // But we only need to load until the terrain is available, no need to load imagery.
      if (!defined(tile.data) || !defined(tile.data.vertexArray)) {
        queueTileLoad(
          primitive,
          primitive._tileLoadQueueMedium,
          tile,
          frameState
        );
      }

      var lastFrame = primitive._lastSelectionFrameNumber;
      var lastFrameSelectionResult =
        tile._lastSelectionResultFrame === lastFrame
          ? tile._lastSelectionResult
          : TileSelectionResult.NONE;
      if (
        lastFrameSelectionResult !== TileSelectionResult.CULLED_BUT_NEEDED &&
        lastFrameSelectionResult !== TileSelectionResult.RENDERED
      ) {
        primitive._tileToUpdateHeights.push(tile);
      }

      tile._lastSelectionResult = TileSelectionResult.CULLED_BUT_NEEDED;
    } else if (primitive.preloadSiblings || tile.level === 0) {
      // Load culled level zero tiles with low priority.
      // For all other levels, only load culled tiles if preloadSiblings is enabled.
      queueTileLoad(primitive, primitive._tileLoadQueueLow, tile, frameState);
      tile._lastSelectionResult = TileSelectionResult.CULLED;
    } else {
      tile._lastSelectionResult = TileSelectionResult.CULLED;
    }

    tile._lastSelectionResultFrame = frameState.frameNumber;
  }

  function screenSpaceError(primitive, frameState, tile) {
    if (
      frameState.mode === SceneMode$1.SCENE2D ||
      frameState.camera.frustum instanceof OrthographicFrustum ||
      frameState.camera.frustum instanceof OrthographicOffCenterFrustum
    ) {
      return screenSpaceError2D(primitive, frameState, tile);
    }

    var maxGeometricError = primitive._tileProvider.getLevelMaximumGeometricError(
      tile.level
    );

    var distance = tile._distance;
    var height = frameState.context.drawingBufferHeight;
    var sseDenominator = frameState.camera.frustum.sseDenominator;

    var error = (maxGeometricError * height) / (distance * sseDenominator);

    if (frameState.fog.enabled) {
      error -=
        CesiumMath.fog(distance, frameState.fog.density) * frameState.fog.sse;
    }

    error /= frameState.pixelRatio;

    return error;
  }

  function screenSpaceError2D(primitive, frameState, tile) {
    var camera = frameState.camera;
    var frustum = camera.frustum;
    if (defined(frustum._offCenterFrustum)) {
      frustum = frustum._offCenterFrustum;
    }

    var context = frameState.context;
    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight;

    var maxGeometricError = primitive._tileProvider.getLevelMaximumGeometricError(
      tile.level
    );
    var pixelSize =
      Math.max(frustum.top - frustum.bottom, frustum.right - frustum.left) /
      Math.max(width, height);
    var error = maxGeometricError / pixelSize;

    if (frameState.fog.enabled && frameState.mode !== SceneMode$1.SCENE2D) {
      error -=
        CesiumMath.fog(tile._distance, frameState.fog.density) *
        frameState.fog.sse;
    }

    error /= frameState.pixelRatio;

    return error;
  }

  function addTileToRenderList(primitive, tile) {
    primitive._tilesToRender.push(tile);
  }

  function processTileLoadQueue(primitive, frameState) {
    var tileLoadQueueHigh = primitive._tileLoadQueueHigh;
    var tileLoadQueueMedium = primitive._tileLoadQueueMedium;
    var tileLoadQueueLow = primitive._tileLoadQueueLow;

    if (
      tileLoadQueueHigh.length === 0 &&
      tileLoadQueueMedium.length === 0 &&
      tileLoadQueueLow.length === 0
    ) {
      return;
    }

    // Remove any tiles that were not used this frame beyond the number
    // we're allowed to keep.
    primitive._tileReplacementQueue.trimTiles(primitive.tileCacheSize);

    var endTime = getTimestamp$1() + primitive._loadQueueTimeSlice;
    var tileProvider = primitive._tileProvider;

    var didSomeLoading = processSinglePriorityLoadQueue(
      primitive,
      frameState,
      tileProvider,
      endTime,
      tileLoadQueueHigh,
      false
    );
    didSomeLoading = processSinglePriorityLoadQueue(
      primitive,
      frameState,
      tileProvider,
      endTime,
      tileLoadQueueMedium,
      didSomeLoading
    );
    processSinglePriorityLoadQueue(
      primitive,
      frameState,
      tileProvider,
      endTime,
      tileLoadQueueLow,
      didSomeLoading
    );
  }

  function sortByLoadPriority(a, b) {
    return a._loadPriority - b._loadPriority;
  }

  function processSinglePriorityLoadQueue(
    primitive,
    frameState,
    tileProvider,
    endTime,
    loadQueue,
    didSomeLoading
  ) {
    if (tileProvider.computeTileLoadPriority !== undefined) {
      loadQueue.sort(sortByLoadPriority);
    }

    for (
      var i = 0, len = loadQueue.length;
      i < len && (getTimestamp$1() < endTime || !didSomeLoading);
      ++i
    ) {
      var tile = loadQueue[i];
      primitive._tileReplacementQueue.markTileRendered(tile);
      tileProvider.loadTile(frameState, tile);
      didSomeLoading = true;
    }

    return didSomeLoading;
  }

  var scratchRay = new Ray();
  var scratchCartographic$d = new Cartographic();
  var scratchPosition$b = new Cartesian3();
  var scratchArray = [];

  function updateHeights(primitive, frameState) {
    if (!primitive.tileProvider.ready) {
      return;
    }

    var tryNextFrame = scratchArray;
    tryNextFrame.length = 0;
    var tilesToUpdateHeights = primitive._tileToUpdateHeights;
    var terrainProvider = primitive._tileProvider.terrainProvider;

    var startTime = getTimestamp$1();
    var timeSlice = primitive._updateHeightsTimeSlice;
    var endTime = startTime + timeSlice;

    var mode = frameState.mode;
    var projection = frameState.mapProjection;
    var ellipsoid = primitive.tileProvider.tilingScheme.ellipsoid;
    var i;

    while (tilesToUpdateHeights.length > 0) {
      var tile = tilesToUpdateHeights[0];
      if (!defined(tile.data) || !defined(tile.data.mesh)) {
        // Tile isn't loaded enough yet, so try again next frame if this tile is still
        // being rendered.
        var selectionResult =
          tile._lastSelectionResultFrame === primitive._lastSelectionFrameNumber
            ? tile._lastSelectionResult
            : TileSelectionResult.NONE;
        if (
          selectionResult === TileSelectionResult.RENDERED ||
          selectionResult === TileSelectionResult.CULLED_BUT_NEEDED
        ) {
          tryNextFrame.push(tile);
        }
        tilesToUpdateHeights.shift();
        primitive._lastTileIndex = 0;
        continue;
      }
      var customData = tile.customData;
      var customDataLength = customData.length;

      var timeSliceMax = false;
      for (i = primitive._lastTileIndex; i < customDataLength; ++i) {
        var data = customData[i];

        if (tile.level > data.level) {
          if (!defined(data.positionOnEllipsoidSurface)) {
            // cartesian has to be on the ellipsoid surface for `ellipsoid.geodeticSurfaceNormal`
            data.positionOnEllipsoidSurface = Cartesian3.fromRadians(
              data.positionCartographic.longitude,
              data.positionCartographic.latitude,
              0.0,
              ellipsoid
            );
          }

          if (mode === SceneMode$1.SCENE3D) {
            var surfaceNormal = ellipsoid.geodeticSurfaceNormal(
              data.positionOnEllipsoidSurface,
              scratchRay.direction
            );

            // compute origin point

            // Try to find the intersection point between the surface normal and z-axis.
            // minimum height (-11500.0) for the terrain set, need to get this information from the terrain provider
            var rayOrigin = ellipsoid.getSurfaceNormalIntersectionWithZAxis(
              data.positionOnEllipsoidSurface,
              11500.0,
              scratchRay.origin
            );

            // Theoretically, not with Earth datums, the intersection point can be outside the ellipsoid
            if (!defined(rayOrigin)) {
              // intersection point is outside the ellipsoid, try other value
              // minimum height (-11500.0) for the terrain set, need to get this information from the terrain provider
              var minimumHeight;
              if (defined(tile.data.tileBoundingRegion)) {
                minimumHeight = tile.data.tileBoundingRegion.minimumHeight;
              }
              var magnitude = Math.min(
                defaultValue(minimumHeight, 0.0),
                -11500.0
              );

              // multiply by the *positive* value of the magnitude
              var vectorToMinimumPoint = Cartesian3.multiplyByScalar(
                surfaceNormal,
                Math.abs(magnitude) + 1,
                scratchPosition$b
              );
              Cartesian3.subtract(
                data.positionOnEllipsoidSurface,
                vectorToMinimumPoint,
                scratchRay.origin
              );
            }
          } else {
            Cartographic.clone(data.positionCartographic, scratchCartographic$d);

            // minimum height for the terrain set, need to get this information from the terrain provider
            scratchCartographic$d.height = -11500.0;
            projection.project(scratchCartographic$d, scratchPosition$b);
            Cartesian3.fromElements(
              scratchPosition$b.z,
              scratchPosition$b.x,
              scratchPosition$b.y,
              scratchPosition$b
            );
            Cartesian3.clone(scratchPosition$b, scratchRay.origin);
            Cartesian3.clone(Cartesian3.UNIT_X, scratchRay.direction);
          }

          var position = tile.data.pick(
            scratchRay,
            mode,
            projection,
            false,
            scratchPosition$b
          );
          if (defined(position)) {
            data.callback(position);
            data.level = tile.level;
          }
        } else if (tile.level === data.level) {
          var children = tile.children;
          var childrenLength = children.length;

          var child;
          for (var j = 0; j < childrenLength; ++j) {
            child = children[j];
            if (Rectangle.contains(child.rectangle, data.positionCartographic)) {
              break;
            }
          }

          var tileDataAvailable = terrainProvider.getTileDataAvailable(
            child.x,
            child.y,
            child.level
          );
          var parentTile = tile.parent;
          if (
            (defined(tileDataAvailable) && !tileDataAvailable) ||
            (defined(parentTile) &&
              defined(parentTile.data) &&
              defined(parentTile.data.terrainData) &&
              !parentTile.data.terrainData.isChildAvailable(
                parentTile.x,
                parentTile.y,
                child.x,
                child.y
              ))
          ) {
            data.removeFunc();
          }
        }

        if (getTimestamp$1() >= endTime) {
          timeSliceMax = true;
          break;
        }
      }

      if (timeSliceMax) {
        primitive._lastTileIndex = i;
        break;
      } else {
        primitive._lastTileIndex = 0;
        tilesToUpdateHeights.shift();
      }
    }
    for (i = 0; i < tryNextFrame.length; i++) {
      tilesToUpdateHeights.push(tryNextFrame[i]);
    }
  }

  function createRenderCommandsForSelectedTiles(primitive, frameState) {
    var tileProvider = primitive._tileProvider;
    var tilesToRender = primitive._tilesToRender;

    for (var i = 0, len = tilesToRender.length; i < len; ++i) {
      var tile = tilesToRender[i];
      tileProvider.showTileThisFrame(tile, frameState);
    }
  }

  /**
   * The globe rendered in the scene, including its terrain ({@link Globe#terrainProvider})
   * and imagery layers ({@link Globe#imageryLayers}).  Access the globe using {@link Scene#globe}.
   *
   * @alias Globe
   * @constructor
   *
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] Determines the size and shape of the
   * globe.
   */
  function Globe(ellipsoid) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
    var terrainProvider = new EllipsoidTerrainProvider({
      ellipsoid: ellipsoid,
    });
    var imageryLayerCollection = new ImageryLayerCollection();

    this._ellipsoid = ellipsoid;
    this._imageryLayerCollection = imageryLayerCollection;

    this._surfaceShaderSet = new GlobeSurfaceShaderSet();
    this._material = undefined;

    this._surface = new QuadtreePrimitive({
      tileProvider: new GlobeSurfaceTileProvider({
        terrainProvider: terrainProvider,
        imageryLayers: imageryLayerCollection,
        surfaceShaderSet: this._surfaceShaderSet,
      }),
    });

    this._terrainProvider = terrainProvider;
    this._terrainProviderChanged = new Event();

    this._undergroundColor = Color.clone(Color.BLACK);
    this._undergroundColorAlphaByDistance = new NearFarScalar(
      ellipsoid.maximumRadius / 1000.0,
      0.0,
      ellipsoid.maximumRadius / 5.0,
      1.0
    );

    this._translucency = new GlobeTranslucency();

    makeShadersDirty(this);

    /**
     * Determines if the globe will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = true;

    this._oceanNormalMapResourceDirty = true;
    this._oceanNormalMapResource = new Resource({
      url: buildModuleUrl("Assets/Textures/waterNormalsSmall.jpg"),
    });

    /**
     * The maximum screen-space error used to drive level-of-detail refinement.  Higher
     * values will provide better performance but lower visual quality.
     *
     * @type {Number}
     * @default 2
     */
    this.maximumScreenSpaceError = 2;

    /**
     * The size of the terrain tile cache, expressed as a number of tiles.  Any additional
     * tiles beyond this number will be freed, as long as they aren't needed for rendering
     * this frame.  A larger number will consume more memory but will show detail faster
     * when, for example, zooming out and then back in.
     *
     * @type {Number}
     * @default 100
     */
    this.tileCacheSize = 100;

    /**
     * Gets or sets the number of loading descendant tiles that is considered "too many".
     * If a tile has too many loading descendants, that tile will be loaded and rendered before any of
     * its descendants are loaded and rendered. This means more feedback for the user that something
     * is happening at the cost of a longer overall load time. Setting this to 0 will cause each
     * tile level to be loaded successively, significantly increasing load time. Setting it to a large
     * number (e.g. 1000) will minimize the number of tiles that are loaded but tend to make
     * detail appear all at once after a long wait.
     * @type {Number}
     * @default 20
     */
    this.loadingDescendantLimit = 20;

    /**
     * Gets or sets a value indicating whether the ancestors of rendered tiles should be preloaded.
     * Setting this to true optimizes the zoom-out experience and provides more detail in
     * newly-exposed areas when panning. The down side is that it requires loading more tiles.
     * @type {Boolean}
     * @default true
     */
    this.preloadAncestors = true;

    /**
     * Gets or sets a value indicating whether the siblings of rendered tiles should be preloaded.
     * Setting this to true causes tiles with the same parent as a rendered tile to be loaded, even
     * if they are culled. Setting this to true may provide a better panning experience at the
     * cost of loading more tiles.
     * @type {Boolean}
     * @default false
     */
    this.preloadSiblings = false;

    /**
     * The color to use to highlight terrain fill tiles. If undefined, fill tiles are not
     * highlighted at all. The alpha value is used to alpha blend with the tile's
     * actual color. Because terrain fill tiles do not represent the actual terrain surface,
     * it may be useful in some applications to indicate visually that they are not to be trusted.
     * @type {Color}
     * @default undefined
     */
    this.fillHighlightColor = undefined;

    /**
     * Enable lighting the globe with the scene's light source.
     *
     * @type {Boolean}
     * @default false
     */
    this.enableLighting = false;

    /**
     * Enable dynamic lighting effects on atmosphere and fog. This only takes effect
     * when <code>enableLighting</code> is <code>true</code>.
     *
     * @type {Boolean}
     * @default true
     */
    this.dynamicAtmosphereLighting = true;

    /**
     * Whether dynamic atmosphere lighting uses the sun direction instead of the scene's
     * light direction. This only takes effect when <code>enableLighting</code> and
     * <code>dynamicAtmosphereLighting</code> are <code>true</code>.
     *
     * @type {Boolean}
     * @default false
     */
    this.dynamicAtmosphereLightingFromSun = false;

    /**
     * Enable the ground atmosphere, which is drawn over the globe when viewed from a distance between <code>lightingFadeInDistance</code> and <code>lightingFadeOutDistance</code>.
     *
     * @demo {@link https://sandcastle.cesium.com/index.html?src=Ground%20Atmosphere.html|Ground atmosphere demo in Sandcastle}
     *
     * @type {Boolean}
     * @default true
     */
    this.showGroundAtmosphere = true;

    /**
     * The distance where everything becomes lit. This only takes effect
     * when <code>enableLighting</code> or <code>showGroundAtmosphere</code> is <code>true</code>.
     *
     * @type {Number}
     * @default 10000000.0
     */
    this.lightingFadeOutDistance = 1.0e7;

    /**
     * The distance where lighting resumes. This only takes effect
     * when <code>enableLighting</code> or <code>showGroundAtmosphere</code> is <code>true</code>.
     *
     * @type {Number}
     * @default 20000000.0
     */
    this.lightingFadeInDistance = 2.0e7;

    /**
     * The distance where the darkness of night from the ground atmosphere fades out to a lit ground atmosphere.
     * This only takes effect when <code>showGroundAtmosphere</code>, <code>enableLighting</code>, and
     * <code>dynamicAtmosphereLighting</code> are <code>true</code>.
     *
     * @type {Number}
     * @default 10000000.0
     */
    this.nightFadeOutDistance = 1.0e7;

    /**
     * The distance where the darkness of night from the ground atmosphere fades in to an unlit ground atmosphere.
     * This only takes effect when <code>showGroundAtmosphere</code>, <code>enableLighting</code>, and
     * <code>dynamicAtmosphereLighting</code> are <code>true</code>.
     *
     * @type {Number}
     * @default 50000000.0
     */
    this.nightFadeInDistance = 5.0e7;

    /**
     * True if an animated wave effect should be shown in areas of the globe
     * covered by water; otherwise, false.  This property is ignored if the
     * <code>terrainProvider</code> does not provide a water mask.
     *
     * @type {Boolean}
     * @default true
     */
    this.showWaterEffect = true;

    /**
     * True if primitives such as billboards, polylines, labels, etc. should be depth-tested
     * against the terrain surface, or false if such primitives should always be drawn on top
     * of terrain unless they're on the opposite side of the globe.  The disadvantage of depth
     * testing primitives against terrain is that slight numerical noise or terrain level-of-detail
     * switched can sometimes make a primitive that should be on the surface disappear underneath it.
     *
     * @type {Boolean}
     * @default false
     *
     */
    this.depthTestAgainstTerrain = false;

    /**
     * Determines whether the globe casts or receives shadows from light sources. Setting the globe
     * to cast shadows may impact performance since the terrain is rendered again from the light's perspective.
     * Currently only terrain that is in view casts shadows. By default the globe does not cast shadows.
     *
     * @type {ShadowMode}
     * @default ShadowMode.RECEIVE_ONLY
     */
    this.shadows = ShadowMode$1.RECEIVE_ONLY;

    /**
     * The hue shift to apply to the atmosphere. Defaults to 0.0 (no shift).
     * A hue shift of 1.0 indicates a complete rotation of the hues available.
     * @type {Number}
     * @default 0.0
     */
    this.atmosphereHueShift = 0.0;

    /**
     * The saturation shift to apply to the atmosphere. Defaults to 0.0 (no shift).
     * A saturation shift of -1.0 is monochrome.
     * @type {Number}
     * @default 0.0
     */
    this.atmosphereSaturationShift = 0.0;

    /**
     * The brightness shift to apply to the atmosphere. Defaults to 0.0 (no shift).
     * A brightness shift of -1.0 is complete darkness, which will let space show through.
     * @type {Number}
     * @default 0.0
     */
    this.atmosphereBrightnessShift = 0.0;

    /**
     * Whether to show terrain skirts. Terrain skirts are geometry extending downwards from a tile's edges used to hide seams between neighboring tiles.
     * Skirts are always hidden when the camera is underground or translucency is enabled.
     *
     * @type {Boolean}
     * @default true
     */
    this.showSkirts = true;

    /**
     * Whether to cull back-facing terrain. Back faces are not culled when the camera is underground or translucency is enabled.
     *
     * @type {Boolean}
     * @default true
     */
    this.backFaceCulling = true;

    this._oceanNormalMap = undefined;
    this._zoomedOutOceanSpecularIntensity = undefined;
  }

  Object.defineProperties(Globe.prototype, {
    /**
     * Gets an ellipsoid describing the shape of this globe.
     * @memberof Globe.prototype
     * @type {Ellipsoid}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
    /**
     * Gets the collection of image layers that will be rendered on this globe.
     * @memberof Globe.prototype
     * @type {ImageryLayerCollection}
     */
    imageryLayers: {
      get: function () {
        return this._imageryLayerCollection;
      },
    },
    /**
     * Gets an event that's raised when an imagery layer is added, shown, hidden, moved, or removed.
     *
     * @memberof Globe.prototype
     * @type {Event}
     * @readonly
     */
    imageryLayersUpdatedEvent: {
      get: function () {
        return this._surface.tileProvider.imageryLayersUpdatedEvent;
      },
    },
    /**
     * Returns <code>true</code> when the tile load queue is empty, <code>false</code> otherwise.  When the load queue is empty,
     * all terrain and imagery for the current view have been loaded.
     * @memberof Globe.prototype
     * @type {Boolean}
     * @readonly
     */
    tilesLoaded: {
      get: function () {
        if (!defined(this._surface)) {
          return true;
        }
        return (
          this._surface.tileProvider.ready &&
          this._surface._tileLoadQueueHigh.length === 0 &&
          this._surface._tileLoadQueueMedium.length === 0 &&
          this._surface._tileLoadQueueLow.length === 0
        );
      },
    },
    /**
     * Gets or sets the color of the globe when no imagery is available.
     * @memberof Globe.prototype
     * @type {Color}
     */
    baseColor: {
      get: function () {
        return this._surface.tileProvider.baseColor;
      },
      set: function (value) {
        this._surface.tileProvider.baseColor = value;
      },
    },
    /**
     * A property specifying a {@link ClippingPlaneCollection} used to selectively disable rendering on the outside of each plane.
     *
     * @memberof Globe.prototype
     * @type {ClippingPlaneCollection}
     */
    clippingPlanes: {
      get: function () {
        return this._surface.tileProvider.clippingPlanes;
      },
      set: function (value) {
        this._surface.tileProvider.clippingPlanes = value;
      },
    },
    /**
     * A property specifying a {@link Rectangle} used to limit globe rendering to a cartographic area.
     * Defaults to the maximum extent of cartographic coordinates.
     *
     * @memberof Globe.prototype
     * @type {Rectangle}
     * @default {@link Rectangle.MAX_VALUE}
     */
    cartographicLimitRectangle: {
      get: function () {
        return this._surface.tileProvider.cartographicLimitRectangle;
      },
      set: function (value) {
        if (!defined(value)) {
          value = Rectangle.clone(Rectangle.MAX_VALUE);
        }
        this._surface.tileProvider.cartographicLimitRectangle = value;
      },
    },
    /**
     * The normal map to use for rendering waves in the ocean.  Setting this property will
     * only have an effect if the configured terrain provider includes a water mask.
     * @memberof Globe.prototype
     * @type {String}
     * @default buildModuleUrl('Assets/Textures/waterNormalsSmall.jpg')
     */
    oceanNormalMapUrl: {
      get: function () {
        return this._oceanNormalMapResource.url;
      },
      set: function (value) {
        this._oceanNormalMapResource.url = value;
        this._oceanNormalMapResourceDirty = true;
      },
    },
    /**
     * The terrain provider providing surface geometry for this globe.
     * @type {TerrainProvider}
     *
     * @memberof Globe.prototype
     * @type {TerrainProvider}
     *
     */
    terrainProvider: {
      get: function () {
        return this._terrainProvider;
      },
      set: function (value) {
        if (value !== this._terrainProvider) {
          this._terrainProvider = value;
          this._terrainProviderChanged.raiseEvent(value);
          if (defined(this._material)) {
            makeShadersDirty(this);
          }
        }
      },
    },
    /**
     * Gets an event that's raised when the terrain provider is changed
     *
     * @memberof Globe.prototype
     * @type {Event}
     * @readonly
     */
    terrainProviderChanged: {
      get: function () {
        return this._terrainProviderChanged;
      },
    },
    /**
     * Gets an event that's raised when the length of the tile load queue has changed since the last render frame.  When the load queue is empty,
     * all terrain and imagery for the current view have been loaded.  The event passes the new length of the tile load queue.
     *
     * @memberof Globe.prototype
     * @type {Event}
     */
    tileLoadProgressEvent: {
      get: function () {
        return this._surface.tileLoadProgressEvent;
      },
    },

    /**
     * Gets or sets the material appearance of the Globe.  This can be one of several built-in {@link Material} objects or a custom material, scripted with
     * {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}.
     * @memberof Globe.prototype
     * @type {Material}
     */
    material: {
      get: function () {
        return this._material;
      },
      set: function (material) {
        if (this._material !== material) {
          this._material = material;
          makeShadersDirty(this);
        }
      },
    },

    /**
     * The color to render the back side of the globe when the camera is underground or the globe is translucent,
     * blended with the globe color based on the camera's distance.
     * <br /><br />
     * To disable underground coloring, set <code>undergroundColor</code> to <code>undefined</code>.
     *
     * @memberof Globe.prototype
     * @type {Color}
     * @default {@link Color.BLACK}
     *
     * @see Globe#undergroundColorAlphaByDistance
     */
    undergroundColor: {
      get: function () {
        return this._undergroundColor;
      },
      set: function (value) {
        this._undergroundColor = Color.clone(value, this._undergroundColor);
      },
    },

    /**
     * Gets or sets the near and far distance for blending {@link Globe#undergroundColor} with the globe color.
     * The alpha will interpolate between the {@link NearFarScalar#nearValue} and
     * {@link NearFarScalar#farValue} while the camera distance falls within the lower and upper bounds
     * of the specified {@link NearFarScalar#near} and {@link NearFarScalar#far}.
     * Outside of these ranges the alpha remains clamped to the nearest bound. If undefined,
     * the underground color will not be blended with the globe color.
     * <br /> <br />
     * When the camera is above the ellipsoid the distance is computed from the nearest
     * point on the ellipsoid instead of the camera's position.
     *
     * @memberof Globe.prototype
     * @type {NearFarScalar}
     *
     * @see Globe#undergroundColor
     *
     */
    undergroundColorAlphaByDistance: {
      get: function () {
        return this._undergroundColorAlphaByDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value.far < value.near) {
          throw new DeveloperError(
            "far distance must be greater than near distance."
          );
        }
        //>>includeEnd('debug');
        this._undergroundColorAlphaByDistance = NearFarScalar.clone(
          value,
          this._undergroundColorAlphaByDistance
        );
      },
    },

    /**
     * Properties for controlling globe translucency.
     *
     * @memberof Globe.prototype
     * @type {GlobeTranslucency}
     */
    translucency: {
      get: function () {
        return this._translucency;
      },
    },
  });

  function makeShadersDirty(globe) {
    var defines = [];

    var requireNormals =
      defined(globe._material) &&
      (globe._material.shaderSource.match(/slope/) ||
        globe._material.shaderSource.match("normalEC"));

    var fragmentSources = [GroundAtmosphere];
    if (
      defined(globe._material) &&
      (!requireNormals || globe._terrainProvider.requestVertexNormals)
    ) {
      fragmentSources.push(globe._material.shaderSource);
      defines.push("APPLY_MATERIAL");
      globe._surface._tileProvider.materialUniformMap = globe._material._uniforms;
    } else {
      globe._surface._tileProvider.materialUniformMap = undefined;
    }
    fragmentSources.push(GlobeFS);

    globe._surfaceShaderSet.baseVertexShaderSource = new ShaderSource({
      sources: [GroundAtmosphere, GlobeVS],
      defines: defines,
    });

    globe._surfaceShaderSet.baseFragmentShaderSource = new ShaderSource({
      sources: fragmentSources,
      defines: defines,
    });
    globe._surfaceShaderSet.material = globe._material;
  }

  function createComparePickTileFunction(rayOrigin) {
    return function (a, b) {
      var aDist = BoundingSphere.distanceSquaredTo(
        a.pickBoundingSphere,
        rayOrigin
      );
      var bDist = BoundingSphere.distanceSquaredTo(
        b.pickBoundingSphere,
        rayOrigin
      );

      return aDist - bDist;
    };
  }

  var scratchArray$1 = [];
  var scratchSphereIntersectionResult = {
    start: 0.0,
    stop: 0.0,
  };

  /**
   * Find an intersection between a ray and the globe surface that was rendered. The ray must be given in world coordinates.
   *
   * @param {Ray} ray The ray to test for intersection.
   * @param {Scene} scene The scene.
   * @param {Boolean} [cullBackFaces=true] Set to true to not pick back faces.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3|undefined} The intersection or <code>undefined</code> if none was found.  The returned position is in projected coordinates for 2D and Columbus View.
   *
   * @private
   */
  Globe.prototype.pickWorldCoordinates = function (
    ray,
    scene,
    cullBackFaces,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(ray)) {
      throw new DeveloperError("ray is required");
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required");
    }
    //>>includeEnd('debug');

    cullBackFaces = defaultValue(cullBackFaces, true);

    var mode = scene.mode;
    var projection = scene.mapProjection;

    var sphereIntersections = scratchArray$1;
    sphereIntersections.length = 0;

    var tilesToRender = this._surface._tilesToRender;
    var length = tilesToRender.length;

    var tile;
    var i;

    for (i = 0; i < length; ++i) {
      tile = tilesToRender[i];
      var surfaceTile = tile.data;

      if (!defined(surfaceTile)) {
        continue;
      }

      var boundingVolume = surfaceTile.pickBoundingSphere;
      if (mode !== SceneMode$1.SCENE3D) {
        surfaceTile.pickBoundingSphere = boundingVolume = BoundingSphere.fromRectangleWithHeights2D(
          tile.rectangle,
          projection,
          surfaceTile.tileBoundingRegion.minimumHeight,
          surfaceTile.tileBoundingRegion.maximumHeight,
          boundingVolume
        );
        Cartesian3.fromElements(
          boundingVolume.center.z,
          boundingVolume.center.x,
          boundingVolume.center.y,
          boundingVolume.center
        );
      } else if (defined(surfaceTile.renderedMesh)) {
        BoundingSphere.clone(
          surfaceTile.renderedMesh.boundingSphere3D,
          boundingVolume
        );
      } else {
        // So wait how did we render this thing then? It shouldn't be possible to get here.
        continue;
      }

      var boundingSphereIntersection = IntersectionTests.raySphere(
        ray,
        boundingVolume,
        scratchSphereIntersectionResult
      );
      if (defined(boundingSphereIntersection)) {
        sphereIntersections.push(surfaceTile);
      }
    }

    sphereIntersections.sort(createComparePickTileFunction(ray.origin));

    var intersection;
    length = sphereIntersections.length;
    for (i = 0; i < length; ++i) {
      intersection = sphereIntersections[i].pick(
        ray,
        scene.mode,
        scene.mapProjection,
        cullBackFaces,
        result
      );
      if (defined(intersection)) {
        break;
      }
    }

    return intersection;
  };

  var cartoScratch$2 = new Cartographic();
  /**
   * Find an intersection between a ray and the globe surface that was rendered. The ray must be given in world coordinates.
   *
   * @param {Ray} ray The ray to test for intersection.
   * @param {Scene} scene The scene.
   * @param {Cartesian3} [result] The object onto which to store the result.
   * @returns {Cartesian3|undefined} The intersection or <code>undefined</code> if none was found.
   *
   * @example
   * // find intersection of ray through a pixel and the globe
   * var ray = viewer.camera.getPickRay(windowCoordinates);
   * var intersection = globe.pick(ray, scene);
   */
  Globe.prototype.pick = function (ray, scene, result) {
    result = this.pickWorldCoordinates(ray, scene, true, result);
    if (defined(result) && scene.mode !== SceneMode$1.SCENE3D) {
      result = Cartesian3.fromElements(result.y, result.z, result.x, result);
      var carto = scene.mapProjection.unproject(result, cartoScratch$2);
      result = scene.globe.ellipsoid.cartographicToCartesian(carto, result);
    }

    return result;
  };

  var scratchGetHeightCartesian = new Cartesian3();
  var scratchGetHeightIntersection = new Cartesian3();
  var scratchGetHeightCartographic = new Cartographic();
  var scratchGetHeightRay = new Ray();

  function tileIfContainsCartographic(tile, cartographic) {
    return defined(tile) && Rectangle.contains(tile.rectangle, cartographic)
      ? tile
      : undefined;
  }

  /**
   * Get the height of the surface at a given cartographic.
   *
   * @param {Cartographic} cartographic The cartographic for which to find the height.
   * @returns {Number|undefined} The height of the cartographic or undefined if it could not be found.
   */
  Globe.prototype.getHeight = function (cartographic) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(cartographic)) {
      throw new DeveloperError("cartographic is required");
    }
    //>>includeEnd('debug');

    var levelZeroTiles = this._surface._levelZeroTiles;
    if (!defined(levelZeroTiles)) {
      return;
    }

    var tile;
    var i;

    var length = levelZeroTiles.length;
    for (i = 0; i < length; ++i) {
      tile = levelZeroTiles[i];
      if (Rectangle.contains(tile.rectangle, cartographic)) {
        break;
      }
    }

    if (i >= length) {
      return undefined;
    }

    var tileWithMesh = tile;

    while (defined(tile)) {
      tile =
        tileIfContainsCartographic(tile._southwestChild, cartographic) ||
        tileIfContainsCartographic(tile._southeastChild, cartographic) ||
        tileIfContainsCartographic(tile._northwestChild, cartographic) ||
        tile._northeastChild;

      if (
        defined(tile) &&
        defined(tile.data) &&
        defined(tile.data.renderedMesh)
      ) {
        tileWithMesh = tile;
      }
    }

    tile = tileWithMesh;

    // This tile was either rendered or culled.
    // It is sometimes useful to get a height from a culled tile,
    // e.g. when we're getting a height in order to place a billboard
    // on terrain, and the camera is looking at that same billboard.
    // The culled tile must have a valid mesh, though.
    if (
      !defined(tile) ||
      !defined(tile.data) ||
      !defined(tile.data.renderedMesh)
    ) {
      // Tile was not rendered (culled).
      return undefined;
    }

    var ellipsoid = this._surface._tileProvider.tilingScheme.ellipsoid;

    //cartesian has to be on the ellipsoid surface for `ellipsoid.geodeticSurfaceNormal`
    var cartesian = Cartesian3.fromRadians(
      cartographic.longitude,
      cartographic.latitude,
      0.0,
      ellipsoid,
      scratchGetHeightCartesian
    );

    var ray = scratchGetHeightRay;
    var surfaceNormal = ellipsoid.geodeticSurfaceNormal(cartesian, ray.direction);

    // Try to find the intersection point between the surface normal and z-axis.
    // minimum height (-11500.0) for the terrain set, need to get this information from the terrain provider
    var rayOrigin = ellipsoid.getSurfaceNormalIntersectionWithZAxis(
      cartesian,
      11500.0,
      ray.origin
    );

    // Theoretically, not with Earth datums, the intersection point can be outside the ellipsoid
    if (!defined(rayOrigin)) {
      // intersection point is outside the ellipsoid, try other value
      // minimum height (-11500.0) for the terrain set, need to get this information from the terrain provider
      var minimumHeight;
      if (defined(tile.data.tileBoundingRegion)) {
        minimumHeight = tile.data.tileBoundingRegion.minimumHeight;
      }
      var magnitude = Math.min(defaultValue(minimumHeight, 0.0), -11500.0);

      // multiply by the *positive* value of the magnitude
      var vectorToMinimumPoint = Cartesian3.multiplyByScalar(
        surfaceNormal,
        Math.abs(magnitude) + 1,
        scratchGetHeightIntersection
      );
      Cartesian3.subtract(cartesian, vectorToMinimumPoint, ray.origin);
    }

    var intersection = tile.data.pick(
      ray,
      undefined,
      undefined,
      false,
      scratchGetHeightIntersection
    );
    if (!defined(intersection)) {
      return undefined;
    }

    return ellipsoid.cartesianToCartographic(
      intersection,
      scratchGetHeightCartographic
    ).height;
  };

  /**
   * @private
   */
  Globe.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    if (frameState.passes.render) {
      this._surface.update(frameState);
    }
  };

  /**
   * @private
   */
  Globe.prototype.beginFrame = function (frameState) {
    var surface = this._surface;
    var tileProvider = surface.tileProvider;
    var terrainProvider = this.terrainProvider;
    var hasWaterMask =
      this.showWaterEffect &&
      terrainProvider.ready &&
      terrainProvider.hasWaterMask;

    if (hasWaterMask && this._oceanNormalMapResourceDirty) {
      // url changed, load new normal map asynchronously
      this._oceanNormalMapResourceDirty = false;
      var oceanNormalMapResource = this._oceanNormalMapResource;
      var oceanNormalMapUrl = oceanNormalMapResource.url;
      if (defined(oceanNormalMapUrl)) {
        var that = this;
        when(oceanNormalMapResource.fetchImage(), function (image) {
          if (oceanNormalMapUrl !== that._oceanNormalMapResource.url) {
            // url changed while we were loading
            return;
          }

          that._oceanNormalMap =
            that._oceanNormalMap && that._oceanNormalMap.destroy();
          that._oceanNormalMap = new Texture({
            context: frameState.context,
            source: image,
          });
        });
      } else {
        this._oceanNormalMap =
          this._oceanNormalMap && this._oceanNormalMap.destroy();
      }
    }

    var pass = frameState.passes;
    var mode = frameState.mode;

    if (pass.render) {
      if (this.showGroundAtmosphere) {
        this._zoomedOutOceanSpecularIntensity = 0.4;
      } else {
        this._zoomedOutOceanSpecularIntensity = 0.5;
      }

      surface.maximumScreenSpaceError = this.maximumScreenSpaceError;
      surface.tileCacheSize = this.tileCacheSize;
      surface.loadingDescendantLimit = this.loadingDescendantLimit;
      surface.preloadAncestors = this.preloadAncestors;
      surface.preloadSiblings = this.preloadSiblings;

      tileProvider.terrainProvider = this.terrainProvider;
      tileProvider.lightingFadeOutDistance = this.lightingFadeOutDistance;
      tileProvider.lightingFadeInDistance = this.lightingFadeInDistance;
      tileProvider.nightFadeOutDistance = this.nightFadeOutDistance;
      tileProvider.nightFadeInDistance = this.nightFadeInDistance;
      tileProvider.zoomedOutOceanSpecularIntensity =
        mode === SceneMode$1.SCENE3D ? this._zoomedOutOceanSpecularIntensity : 0.0;
      tileProvider.hasWaterMask = hasWaterMask;
      tileProvider.oceanNormalMap = this._oceanNormalMap;
      tileProvider.enableLighting = this.enableLighting;
      tileProvider.dynamicAtmosphereLighting = this.dynamicAtmosphereLighting;
      tileProvider.dynamicAtmosphereLightingFromSun = this.dynamicAtmosphereLightingFromSun;
      tileProvider.showGroundAtmosphere = this.showGroundAtmosphere;
      tileProvider.shadows = this.shadows;
      tileProvider.hueShift = this.atmosphereHueShift;
      tileProvider.saturationShift = this.atmosphereSaturationShift;
      tileProvider.brightnessShift = this.atmosphereBrightnessShift;
      tileProvider.fillHighlightColor = this.fillHighlightColor;
      tileProvider.showSkirts = this.showSkirts;
      tileProvider.backFaceCulling = this.backFaceCulling;
      tileProvider.undergroundColor = this._undergroundColor;
      tileProvider.undergroundColorAlphaByDistance = this._undergroundColorAlphaByDistance;
      surface.beginFrame(frameState);
    }
  };

  /**
   * @private
   */
  Globe.prototype.render = function (frameState) {
    if (!this.show) {
      return;
    }

    if (defined(this._material)) {
      this._material.update(frameState.context);
    }

    this._surface.render(frameState);
  };

  /**
   * @private
   */
  Globe.prototype.endFrame = function (frameState) {
    if (!this.show) {
      return;
    }

    if (frameState.passes.render) {
      this._surface.endFrame(frameState);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see Globe#destroy
   */
  Globe.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * globe = globe && globe.destroy();
   *
   * @see Globe#isDestroyed
   */
  Globe.prototype.destroy = function () {
    this._surfaceShaderSet =
      this._surfaceShaderSet && this._surfaceShaderSet.destroy();
    this._surface = this._surface && this._surface.destroy();
    this._oceanNormalMap = this._oceanNormalMap && this._oceanNormalMap.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var PassThrough = "uniform sampler2D colorTexture;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
gl_FragColor = texture2D(colorTexture, v_textureCoordinates);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var PassThroughDepth = "uniform sampler2D u_depthTexture;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
gl_FragColor = czm_packDepth(texture2D(u_depthTexture, v_textureCoordinates).r);\n\
}\n\
";

  /**
   * @private
   */
  function GlobeDepth() {
    this._globeColorTexture = undefined;
    this._primitiveColorTexture = undefined;
    this._depthStencilTexture = undefined;
    this._globeDepthTexture = undefined;
    this._tempGlobeDepthTexture = undefined;
    this._tempCopyDepthTexture = undefined;

    this._globeColorFramebuffer = undefined;
    this._primitiveColorFramebuffer = undefined;
    this._copyDepthFramebuffer = undefined;
    this._tempCopyDepthFramebuffer = undefined;
    this._updateDepthFramebuffer = undefined;

    this._clearGlobeColorCommand = undefined;
    this._clearPrimitiveColorCommand = undefined;
    this._copyColorCommand = undefined;
    this._copyDepthCommand = undefined;
    this._tempCopyDepthCommand = undefined;
    this._updateDepthCommand = undefined;
    this._mergeColorCommand = undefined;

    this._viewport = new BoundingRectangle();
    this._rs = undefined;
    this._rsBlend = undefined;
    this._rsUpdate = undefined;

    this._useScissorTest = false;
    this._scissorRectangle = undefined;

    this._useLogDepth = undefined;
    this._useHdr = undefined;
    this._clearGlobeDepth = undefined;

    this._debugGlobeDepthViewportCommand = undefined;
  }

  Object.defineProperties(GlobeDepth.prototype, {
    framebuffer: {
      get: function () {
        return this._globeColorFramebuffer;
      },
    },
    primitiveFramebuffer: {
      get: function () {
        return this._primitiveColorFramebuffer;
      },
    },
  });

  function executeDebugGlobeDepth(globeDepth, context, passState, useLogDepth) {
    if (
      !defined(globeDepth._debugGlobeDepthViewportCommand) ||
      useLogDepth !== globeDepth._useLogDepth
    ) {
      var fsSource =
        "uniform sampler2D u_depthTexture;\n" +
        "varying vec2 v_textureCoordinates;\n" +
        "void main()\n" +
        "{\n" +
        "    float z_window = czm_unpackDepth(texture2D(u_depthTexture, v_textureCoordinates));\n" +
        "    z_window = czm_reverseLogDepth(z_window); \n" +
        "    float n_range = czm_depthRange.near;\n" +
        "    float f_range = czm_depthRange.far;\n" +
        "    float z_ndc = (2.0 * z_window - n_range - f_range) / (f_range - n_range);\n" +
        "    float scale = pow(z_ndc * 0.5 + 0.5, 8.0);\n" +
        "    gl_FragColor = vec4(mix(vec3(0.0), vec3(1.0), scale), 1.0);\n" +
        "}\n";
      var fs = new ShaderSource({
        defines: [useLogDepth ? "LOG_DEPTH" : ""],
        sources: [fsSource],
      });

      globeDepth._debugGlobeDepthViewportCommand = context.createViewportQuadCommand(
        fs,
        {
          uniformMap: {
            u_depthTexture: function () {
              return globeDepth._globeDepthTexture;
            },
          },
          owner: globeDepth,
        }
      );

      globeDepth._useLogDepth = useLogDepth;
    }

    globeDepth._debugGlobeDepthViewportCommand.execute(context, passState);
  }

  function destroyTextures(globeDepth) {
    globeDepth._globeColorTexture =
      globeDepth._globeColorTexture &&
      !globeDepth._globeColorTexture.isDestroyed() &&
      globeDepth._globeColorTexture.destroy();
    globeDepth._depthStencilTexture =
      globeDepth._depthStencilTexture &&
      !globeDepth._depthStencilTexture.isDestroyed() &&
      globeDepth._depthStencilTexture.destroy();
    globeDepth._globeDepthTexture =
      globeDepth._globeDepthTexture &&
      !globeDepth._globeDepthTexture.isDestroyed() &&
      globeDepth._globeDepthTexture.destroy();
  }

  function destroyFramebuffers$1(globeDepth) {
    globeDepth._globeColorFramebuffer =
      globeDepth._globeColorFramebuffer &&
      !globeDepth._globeColorFramebuffer.isDestroyed() &&
      globeDepth._globeColorFramebuffer.destroy();
    globeDepth._copyDepthFramebuffer =
      globeDepth._copyDepthFramebuffer &&
      !globeDepth._copyDepthFramebuffer.isDestroyed() &&
      globeDepth._copyDepthFramebuffer.destroy();
  }

  function destroyUpdateDepthResources(globeDepth) {
    globeDepth._tempCopyDepthFramebuffer =
      globeDepth._tempCopyDepthFramebuffer &&
      !globeDepth._tempCopyDepthFramebuffer.isDestroyed() &&
      globeDepth._tempCopyDepthFramebuffer.destroy();
    globeDepth._updateDepthFramebuffer =
      globeDepth._updateDepthFramebuffer &&
      !globeDepth._updateDepthFramebuffer.isDestroyed() &&
      globeDepth._updateDepthFramebuffer.destroy();
    globeDepth._tempGlobeDepthTexture =
      globeDepth._tempGlobeDepthTexture &&
      !globeDepth._tempGlobeDepthTexture.isDestroyed() &&
      globeDepth._tempGlobeDepthTexture.destroy();
  }

  function createUpdateDepthResources(
    globeDepth,
    context,
    width,
    height,
    passState
  ) {
    globeDepth._tempGlobeDepthTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });
    globeDepth._tempCopyDepthFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeDepth._tempGlobeDepthTexture],
      destroyAttachments: false,
    });
    globeDepth._updateDepthFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeDepth._globeDepthTexture],
      depthStencilTexture: passState.framebuffer.depthStencilTexture,
      destroyAttachments: false,
    });
  }

  function createTextures$1(globeDepth, context, width, height, hdr) {
    var pixelDatatype = hdr
      ? context.halfFloatingPointTexture
        ? PixelDatatype$1.HALF_FLOAT
        : PixelDatatype$1.FLOAT
      : PixelDatatype$1.UNSIGNED_BYTE;
    globeDepth._globeColorTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: pixelDatatype,
      sampler: Sampler.NEAREST,
    });

    globeDepth._depthStencilTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.DEPTH_STENCIL,
      pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
    });

    globeDepth._globeDepthTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });
  }

  function createFramebuffers$1(globeDepth, context) {
    globeDepth._globeColorFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeDepth._globeColorTexture],
      depthStencilTexture: globeDepth._depthStencilTexture,
      destroyAttachments: false,
    });

    globeDepth._copyDepthFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeDepth._globeDepthTexture],
      destroyAttachments: false,
    });
  }

  function createPrimitiveFramebuffer(globeDepth, context, width, height, hdr) {
    var pixelDatatype = hdr
      ? context.halfFloatingPointTexture
        ? PixelDatatype$1.HALF_FLOAT
        : PixelDatatype$1.FLOAT
      : PixelDatatype$1.UNSIGNED_BYTE;
    globeDepth._primitiveColorTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: pixelDatatype,
      sampler: Sampler.NEAREST,
    });

    globeDepth._primitiveColorFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeDepth._primitiveColorTexture],
      depthStencilTexture: globeDepth._depthStencilTexture,
      destroyAttachments: false,
    });
  }

  function destroyPrimitiveFramebuffer(globeDepth) {
    globeDepth._primitiveColorTexture =
      globeDepth._primitiveColorTexture &&
      !globeDepth._primitiveColorTexture.isDestroyed() &&
      globeDepth._primitiveColorTexture.destroy();
    globeDepth._primitiveColorFramebuffer =
      globeDepth._primitiveColorFramebuffer &&
      !globeDepth._primitiveColorFramebuffer.isDestroyed() &&
      globeDepth._primitiveColorFramebuffer.destroy();
  }

  function updateFramebuffers(
    globeDepth,
    context,
    width,
    height,
    hdr,
    clearGlobeDepth
  ) {
    var colorTexture = globeDepth._globeColorTexture;
    var textureChanged =
      !defined(colorTexture) ||
      colorTexture.width !== width ||
      colorTexture.height !== height ||
      hdr !== globeDepth._useHdr;
    if (textureChanged) {
      destroyTextures(globeDepth);
      destroyFramebuffers$1(globeDepth);
      createTextures$1(globeDepth, context, width, height, hdr);
      createFramebuffers$1(globeDepth, context);
    }

    if (textureChanged || clearGlobeDepth !== globeDepth._clearGlobeDepth) {
      destroyPrimitiveFramebuffer(globeDepth);
      if (clearGlobeDepth) {
        createPrimitiveFramebuffer(globeDepth, context, width, height, hdr);
      }
    }
  }

  function updateCopyCommands(globeDepth, context, width, height, passState) {
    globeDepth._viewport.width = width;
    globeDepth._viewport.height = height;

    var useScissorTest = !BoundingRectangle.equals(
      globeDepth._viewport,
      passState.viewport
    );
    var updateScissor = useScissorTest !== globeDepth._useScissorTest;
    globeDepth._useScissorTest = useScissorTest;

    if (
      !BoundingRectangle.equals(globeDepth._scissorRectangle, passState.viewport)
    ) {
      globeDepth._scissorRectangle = BoundingRectangle.clone(
        passState.viewport,
        globeDepth._scissorRectangle
      );
      updateScissor = true;
    }

    if (
      !defined(globeDepth._rs) ||
      !BoundingRectangle.equals(globeDepth._viewport, globeDepth._rs.viewport) ||
      updateScissor
    ) {
      globeDepth._rs = RenderState.fromCache({
        viewport: globeDepth._viewport,
        scissorTest: {
          enabled: globeDepth._useScissorTest,
          rectangle: globeDepth._scissorRectangle,
        },
      });
      globeDepth._rsBlend = RenderState.fromCache({
        viewport: globeDepth._viewport,
        scissorTest: {
          enabled: globeDepth._useScissorTest,
          rectangle: globeDepth._scissorRectangle,
        },
        blending: BlendingState$1.ALPHA_BLEND,
      });

      // Copy packed depth only if the 3D Tiles bit is set
      globeDepth._rsUpdate = RenderState.fromCache({
        viewport: globeDepth._viewport,
        scissorTest: {
          enabled: globeDepth._useScissorTest,
          rectangle: globeDepth._scissorRectangle,
        },
        stencilTest: {
          enabled: true,
          frontFunction: StencilFunction$1.EQUAL,
          frontOperation: {
            fail: StencilOperation$1.KEEP,
            zFail: StencilOperation$1.KEEP,
            zPass: StencilOperation$1.KEEP,
          },
          backFunction: StencilFunction$1.NEVER,
          reference: StencilConstants$1.CESIUM_3D_TILE_MASK,
          mask: StencilConstants$1.CESIUM_3D_TILE_MASK,
        },
      });
    }

    if (!defined(globeDepth._copyDepthCommand)) {
      globeDepth._copyDepthCommand = context.createViewportQuadCommand(
        PassThroughDepth,
        {
          uniformMap: {
            u_depthTexture: function () {
              return globeDepth._depthStencilTexture;
            },
          },
          owner: globeDepth,
        }
      );
    }

    globeDepth._copyDepthCommand.framebuffer = globeDepth._copyDepthFramebuffer;
    globeDepth._copyDepthCommand.renderState = globeDepth._rs;

    if (!defined(globeDepth._copyColorCommand)) {
      globeDepth._copyColorCommand = context.createViewportQuadCommand(
        PassThrough,
        {
          uniformMap: {
            colorTexture: function () {
              return globeDepth._globeColorTexture;
            },
          },
          owner: globeDepth,
        }
      );
    }

    globeDepth._copyColorCommand.renderState = globeDepth._rs;

    if (!defined(globeDepth._tempCopyDepthCommand)) {
      globeDepth._tempCopyDepthCommand = context.createViewportQuadCommand(
        PassThroughDepth,
        {
          uniformMap: {
            u_depthTexture: function () {
              return globeDepth._tempCopyDepthTexture;
            },
          },
          owner: globeDepth,
        }
      );
    }

    globeDepth._tempCopyDepthCommand.framebuffer =
      globeDepth._tempCopyDepthFramebuffer;
    globeDepth._tempCopyDepthCommand.renderState = globeDepth._rs;

    if (!defined(globeDepth._updateDepthCommand)) {
      globeDepth._updateDepthCommand = context.createViewportQuadCommand(
        PassThrough,
        {
          uniformMap: {
            colorTexture: function () {
              return globeDepth._tempGlobeDepthTexture;
            },
          },
          owner: globeDepth,
        }
      );
    }

    globeDepth._updateDepthCommand.framebuffer =
      globeDepth._updateDepthFramebuffer;
    globeDepth._updateDepthCommand.renderState = globeDepth._rsUpdate;

    if (!defined(globeDepth._clearGlobeColorCommand)) {
      globeDepth._clearGlobeColorCommand = new ClearCommand({
        color: new Color(0.0, 0.0, 0.0, 0.0),
        stencil: 0.0,
        owner: globeDepth,
      });
    }

    globeDepth._clearGlobeColorCommand.framebuffer =
      globeDepth._globeColorFramebuffer;

    if (!defined(globeDepth._clearPrimitiveColorCommand)) {
      globeDepth._clearPrimitiveColorCommand = new ClearCommand({
        color: new Color(0.0, 0.0, 0.0, 0.0),
        stencil: 0.0,
        owner: globeDepth,
      });
    }

    globeDepth._clearPrimitiveColorCommand.framebuffer =
      globeDepth._primitiveColorFramebuffer;

    if (!defined(globeDepth._mergeColorCommand)) {
      globeDepth._mergeColorCommand = context.createViewportQuadCommand(
        PassThrough,
        {
          uniformMap: {
            colorTexture: function () {
              return globeDepth._primitiveColorTexture;
            },
          },
          owner: globeDepth,
        }
      );
    }

    globeDepth._mergeColorCommand.framebuffer = globeDepth._globeColorFramebuffer;
    globeDepth._mergeColorCommand.renderState = globeDepth._rsBlend;
  }

  GlobeDepth.prototype.executeDebugGlobeDepth = function (
    context,
    passState,
    useLogDepth
  ) {
    executeDebugGlobeDepth(this, context, passState, useLogDepth);
  };

  GlobeDepth.prototype.update = function (
    context,
    passState,
    viewport,
    hdr,
    clearGlobeDepth
  ) {
    var width = viewport.width;
    var height = viewport.height;

    updateFramebuffers(this, context, width, height, hdr, clearGlobeDepth);
    updateCopyCommands(this, context, width, height, passState);
    context.uniformState.globeDepthTexture = undefined;

    this._useHdr = hdr;
    this._clearGlobeDepth = clearGlobeDepth;
  };

  GlobeDepth.prototype.executeCopyDepth = function (context, passState) {
    if (defined(this._copyDepthCommand)) {
      this._copyDepthCommand.execute(context, passState);
      context.uniformState.globeDepthTexture = this._globeDepthTexture;
    }
  };

  GlobeDepth.prototype.executeUpdateDepth = function (
    context,
    passState,
    clearGlobeDepth
  ) {
    var depthTextureToCopy = passState.framebuffer.depthStencilTexture;
    if (clearGlobeDepth || depthTextureToCopy !== this._depthStencilTexture) {
      // First copy the depth to a temporary globe depth texture, then update the
      // main globe depth texture where the stencil bit for 3D Tiles is set.
      // This preserves the original globe depth except where 3D Tiles is rendered.
      // The additional texture and framebuffer resources are created on demand.
      if (defined(this._updateDepthCommand)) {
        if (
          !defined(this._updateDepthFramebuffer) ||
          this._updateDepthFramebuffer.depthStencilTexture !==
            depthTextureToCopy ||
          this._updateDepthFramebuffer.getColorTexture(0) !==
            this._globeDepthTexture
        ) {
          var width = this._globeDepthTexture.width;
          var height = this._globeDepthTexture.height;
          destroyUpdateDepthResources(this);
          createUpdateDepthResources(this, context, width, height, passState);
          updateCopyCommands(this, context, width, height, passState);
        }
        this._tempCopyDepthTexture = depthTextureToCopy;
        this._tempCopyDepthCommand.execute(context, passState);
        this._updateDepthCommand.execute(context, passState);
      }
      return;
    }

    // Fast path - the depth texture can be copied normally.
    if (defined(this._copyDepthCommand)) {
      this._copyDepthCommand.execute(context, passState);
    }
  };

  GlobeDepth.prototype.executeCopyColor = function (context, passState) {
    if (defined(this._copyColorCommand)) {
      this._copyColorCommand.execute(context, passState);
    }
  };

  GlobeDepth.prototype.executeMergeColor = function (context, passState) {
    if (defined(this._mergeColorCommand)) {
      this._mergeColorCommand.execute(context, passState);
    }
  };

  GlobeDepth.prototype.clear = function (context, passState, clearColor) {
    var clear = this._clearGlobeColorCommand;
    if (defined(clear)) {
      Color.clone(clearColor, clear.color);
      clear.execute(context, passState);
    }
    clear = this._clearPrimitiveColorCommand;
    if (defined(clear) && defined(this._primitiveColorFramebuffer)) {
      clear.execute(context, passState);
    }
  };

  GlobeDepth.prototype.isDestroyed = function () {
    return false;
  };

  GlobeDepth.prototype.destroy = function () {
    destroyTextures(this);
    destroyFramebuffers$1(this);
    destroyPrimitiveFramebuffer(this);
    destroyUpdateDepthResources(this);

    if (defined(this._copyColorCommand)) {
      this._copyColorCommand.shaderProgram = this._copyColorCommand.shaderProgram.destroy();
    }

    if (defined(this._copyDepthCommand)) {
      this._copyDepthCommand.shaderProgram = this._copyDepthCommand.shaderProgram.destroy();
    }

    if (defined(this._tempCopyDepthCommand)) {
      this._tempCopyDepthCommand.shaderProgram = this._tempCopyDepthCommand.shaderProgram.destroy();
    }

    if (defined(this._updateDepthCommand)) {
      this._updateDepthCommand.shaderProgram = this._updateDepthCommand.shaderProgram.destroy();
    }

    if (defined(this._mergeColorCommand)) {
      this._mergeColorCommand.shaderProgram = this._mergeColorCommand.shaderProgram.destroy();
    }

    if (defined(this._debugGlobeDepthViewportCommand)) {
      this._debugGlobeDepthViewportCommand.shaderProgram = this._debugGlobeDepthViewportCommand.shaderProgram.destroy();
    }

    return destroyObject(this);
  };

  /**
   * @private
   */
  function GlobeTranslucencyFramebuffer() {
    this._colorTexture = undefined;
    this._depthStencilTexture = undefined;
    this._depthStencilRenderbuffer = undefined;
    this._framebuffer = undefined;

    this._packedDepthTexture = undefined;
    this._packedDepthFramebuffer = undefined;

    this._renderState = undefined;

    this._packedDepthCommand = undefined;
    this._clearCommand = undefined;

    this._viewport = new BoundingRectangle();
    this._useScissorTest = false;
    this._scissorRectangle = undefined;
    this._useHdr = undefined;
  }

  Object.defineProperties(GlobeTranslucencyFramebuffer.prototype, {
    classificationTexture: {
      get: function () {
        return this._colorTexture;
      },
    },
    classificationFramebuffer: {
      get: function () {
        return this._framebuffer;
      },
    },
  });

  function destroyResources(globeTranslucency) {
    globeTranslucency._colorTexture =
      globeTranslucency._colorTexture &&
      !globeTranslucency._colorTexture.isDestroyed() &&
      globeTranslucency._colorTexture.destroy();
    globeTranslucency._depthStencilTexture =
      globeTranslucency._depthStencilTexture &&
      !globeTranslucency._depthStencilTexture.isDestroyed() &&
      globeTranslucency._depthStencilTexture.destroy();
    globeTranslucency._depthStencilRenderbuffer =
      globeTranslucency._depthStencilRenderbuffer &&
      !globeTranslucency._depthStencilRenderbuffer.isDestroyed() &&
      globeTranslucency._depthStencilRenderbuffer.destroy();
    globeTranslucency._framebuffer =
      globeTranslucency._framebuffer &&
      !globeTranslucency._framebuffer.isDestroyed() &&
      globeTranslucency._framebuffer.destroy();
    globeTranslucency._packedDepthTexture =
      globeTranslucency._packedDepthTexture &&
      !globeTranslucency._packedDepthTexture.isDestroyed() &&
      globeTranslucency._packedDepthTexture.destroy();
    globeTranslucency._packedDepthFramebuffer =
      globeTranslucency._packedDepthFramebuffer &&
      !globeTranslucency._packedDepthFramebuffer.isDestroyed() &&
      globeTranslucency._packedDepthFramebuffer.destroy();
  }

  function createResources$5(globeTranslucency, context, width, height, hdr) {
    var pixelDatatype = hdr
      ? context.halfFloatingPointTexture
        ? PixelDatatype$1.HALF_FLOAT
        : PixelDatatype$1.FLOAT
      : PixelDatatype$1.UNSIGNED_BYTE;
    globeTranslucency._colorTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: pixelDatatype,
      sampler: Sampler.NEAREST,
    });

    if (context.depthTexture) {
      globeTranslucency._depthStencilTexture = new Texture({
        context: context,
        width: width,
        height: height,
        pixelFormat: PixelFormat$1.DEPTH_STENCIL,
        pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
      });
    } else {
      globeTranslucency._depthStencilRenderbuffer = new Renderbuffer({
        context: context,
        width: width,
        height: height,
        format: RenderbufferFormat$1.DEPTH_STENCIL,
      });
    }

    globeTranslucency._framebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeTranslucency._colorTexture],
      depthStencilTexture: globeTranslucency._depthStencilTexture,
      depthStencilRenderbuffer: globeTranslucency._depthStencilRenderbuffer,
      destroyAttachments: false,
    });

    globeTranslucency._packedDepthTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    globeTranslucency._packedDepthFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [globeTranslucency._packedDepthTexture],
      destroyAttachments: false,
    });
  }

  function updateResources(globeTranslucency, context, width, height, hdr) {
    var colorTexture = globeTranslucency._colorTexture;
    var textureChanged =
      !defined(colorTexture) ||
      colorTexture.width !== width ||
      colorTexture.height !== height ||
      hdr !== globeTranslucency._useHdr;
    if (textureChanged) {
      destroyResources(globeTranslucency);
      createResources$5(globeTranslucency, context, width, height, hdr);
    }
  }

  function updateCommands(globeTranslucency, context, width, height, passState) {
    globeTranslucency._viewport.width = width;
    globeTranslucency._viewport.height = height;

    var useScissorTest = !BoundingRectangle.equals(
      globeTranslucency._viewport,
      passState.viewport
    );
    var updateScissor = useScissorTest !== globeTranslucency._useScissorTest;
    globeTranslucency._useScissorTest = useScissorTest;

    if (
      !BoundingRectangle.equals(
        globeTranslucency._scissorRectangle,
        passState.viewport
      )
    ) {
      globeTranslucency._scissorRectangle = BoundingRectangle.clone(
        passState.viewport,
        globeTranslucency._scissorRectangle
      );
      updateScissor = true;
    }

    if (
      !defined(globeTranslucency._renderState) ||
      !BoundingRectangle.equals(
        globeTranslucency._viewport,
        globeTranslucency._renderState.viewport
      ) ||
      updateScissor
    ) {
      globeTranslucency._renderState = RenderState.fromCache({
        viewport: globeTranslucency._viewport,
        scissorTest: {
          enabled: globeTranslucency._useScissorTest,
          rectangle: globeTranslucency._scissorRectangle,
        },
      });
    }

    if (!defined(globeTranslucency._packedDepthCommand)) {
      globeTranslucency._packedDepthCommand = context.createViewportQuadCommand(
        PassThroughDepth,
        {
          uniformMap: {
            u_depthTexture: function () {
              return globeTranslucency._depthStencilTexture;
            },
          },
          owner: globeTranslucency,
        }
      );
    }

    if (!defined(globeTranslucency._clearCommand)) {
      globeTranslucency._clearCommand = new ClearCommand({
        color: new Color(0.0, 0.0, 0.0, 0.0),
        depth: 1.0,
        stencil: 0.0,
        owner: globeTranslucency,
      });
    }

    globeTranslucency._packedDepthCommand.framebuffer =
      globeTranslucency._packedDepthFramebuffer;
    globeTranslucency._packedDepthCommand.renderState =
      globeTranslucency._renderState;
    globeTranslucency._clearCommand.framebuffer = globeTranslucency._framebuffer;
    globeTranslucency._clearCommand.renderState = globeTranslucency._renderState;
  }

  GlobeTranslucencyFramebuffer.prototype.updateAndClear = function (
    hdr,
    viewport,
    context,
    passState
  ) {
    var width = viewport.width;
    var height = viewport.height;

    updateResources(this, context, width, height, hdr);
    updateCommands(this, context, width, height, passState);

    this._useHdr = hdr;
  };

  GlobeTranslucencyFramebuffer.prototype.clearClassification = function (
    context,
    passState
  ) {
    this._clearCommand.execute(context, passState);
  };

  GlobeTranslucencyFramebuffer.prototype.packDepth = function (
    context,
    passState
  ) {
    this._packedDepthCommand.execute(context, passState);
    return this._packedDepthTexture;
  };

  GlobeTranslucencyFramebuffer.prototype.isDestroyed = function () {
    return false;
  };

  GlobeTranslucencyFramebuffer.prototype.destroy = function () {
    destroyResources(this);
    return destroyObject(this);
  };

  var DerivedCommandType = {
    OPAQUE_FRONT_FACE: 0,
    OPAQUE_BACK_FACE: 1,
    DEPTH_ONLY_FRONT_FACE: 2,
    DEPTH_ONLY_BACK_FACE: 3,
    DEPTH_ONLY_FRONT_AND_BACK_FACE: 4,
    TRANSLUCENT_FRONT_FACE: 5,
    TRANSLUCENT_BACK_FACE: 6,
    TRANSLUCENT_FRONT_FACE_MANUAL_DEPTH_TEST: 7,
    TRANSLUCENT_BACK_FACE_MANUAL_DEPTH_TEST: 8,
    PICK_FRONT_FACE: 9,
    PICK_BACK_FACE: 10,
    DERIVED_COMMANDS_MAXIMUM_LENGTH: 11,
  };

  var derivedCommandsMaximumLength =
    DerivedCommandType.DERIVED_COMMANDS_MAXIMUM_LENGTH;

  var DerivedCommandNames = [
    "opaqueFrontFaceCommand",
    "opaqueBackFaceCommand",
    "depthOnlyFrontFaceCommand",
    "depthOnlyBackFaceCommand",
    "depthOnlyFrontAndBackFaceCommand",
    "translucentFrontFaceCommand",
    "translucentBackFaceCommand",
    "translucentFrontFaceManualDepthTestCommand",
    "translucentBackFaceManualDepthTestCommand",
    "pickFrontFaceCommand",
    "pickBackFaceCommand",
  ];

  /**
   * @private
   */
  function GlobeTranslucencyState() {
    this._frontFaceAlphaByDistance = new NearFarScalar(0.0, 1.0, 0.0, 1.0);
    this._backFaceAlphaByDistance = new NearFarScalar(0.0, 1.0, 0.0, 1.0);

    this._frontFaceTranslucent = false;
    this._backFaceTranslucent = false;
    this._requiresManualDepthTest = false;
    this._sunVisibleThroughGlobe = false;
    this._environmentVisible = false;
    this._useDepthPlane = false;
    this._numberOfTextureUniforms = 0;
    this._globeTranslucencyFramebuffer = undefined;
    this._rectangle = Rectangle.clone(Rectangle.MAX_VALUE);

    this._derivedCommandKey = 0;
    this._derivedCommandsDirty = false;
    this._derivedCommandPacks = undefined;

    this._derivedCommandTypes = new Array(derivedCommandsMaximumLength);
    this._derivedBlendCommandTypes = new Array(derivedCommandsMaximumLength);
    this._derivedPickCommandTypes = new Array(derivedCommandsMaximumLength);
    this._derivedCommandTypesToUpdate = new Array(derivedCommandsMaximumLength);

    this._derivedCommandsLength = 0;
    this._derivedBlendCommandsLength = 0;
    this._derivedPickCommandsLength = 0;
    this._derivedCommandsToUpdateLength = 0;
  }

  Object.defineProperties(GlobeTranslucencyState.prototype, {
    frontFaceAlphaByDistance: {
      get: function () {
        return this._frontFaceAlphaByDistance;
      },
    },
    backFaceAlphaByDistance: {
      get: function () {
        return this._backFaceAlphaByDistance;
      },
    },
    translucent: {
      get: function () {
        return this._frontFaceTranslucent;
      },
    },
    sunVisibleThroughGlobe: {
      get: function () {
        return this._sunVisibleThroughGlobe;
      },
    },
    environmentVisible: {
      get: function () {
        return this._environmentVisible;
      },
    },
    useDepthPlane: {
      get: function () {
        return this._useDepthPlane;
      },
    },
    numberOfTextureUniforms: {
      get: function () {
        return this._numberOfTextureUniforms;
      },
    },
    rectangle: {
      get: function () {
        return this._rectangle;
      },
    },
  });

  GlobeTranslucencyState.prototype.update = function (scene) {
    var globe = scene.globe;
    if (!defined(globe) || !globe.show) {
      this._frontFaceTranslucent = false;
      this._backFaceTranslucent = false;
      this._sunVisibleThroughGlobe = true;
      this._environmentVisible = true;
      this._useDepthPlane = false;
      return;
    }

    this._frontFaceAlphaByDistance = updateAlphaByDistance(
      globe.translucency.enabled,
      globe.translucency.frontFaceAlpha,
      globe.translucency.frontFaceAlphaByDistance,
      this._frontFaceAlphaByDistance
    );
    this._backFaceAlphaByDistance = updateAlphaByDistance(
      globe.translucency.enabled,
      globe.translucency.backFaceAlpha,
      globe.translucency.backFaceAlphaByDistance,
      this._backFaceAlphaByDistance
    );

    this._frontFaceTranslucent = isFaceTranslucent(
      globe.translucency.enabled,
      this._frontFaceAlphaByDistance,
      globe
    );
    this._backFaceTranslucent = isFaceTranslucent(
      globe.translucency.enabled,
      this._backFaceAlphaByDistance,
      globe
    );

    this._requiresManualDepthTest = requiresManualDepthTest(this, scene, globe);

    this._sunVisibleThroughGlobe = isSunVisibleThroughGlobe(this, scene);
    this._environmentVisible = isEnvironmentVisible(this, scene);
    this._useDepthPlane = useDepthPlane(this, scene);
    this._numberOfTextureUniforms = getNumberOfTextureUniforms(this);

    this._rectangle = Rectangle.clone(
      globe.translucency.rectangle,
      this._rectangle
    );

    gatherDerivedCommandRequirements(this, scene);
  };

  function updateAlphaByDistance(enabled, alpha, alphaByDistance, result) {
    if (!enabled) {
      result.nearValue = 1.0;
      result.farValue = 1.0;
      return result;
    }

    if (!defined(alphaByDistance)) {
      result.nearValue = alpha;
      result.farValue = alpha;
      return result;
    }

    NearFarScalar.clone(alphaByDistance, result);
    result.nearValue *= alpha;
    result.farValue *= alpha;
    return result;
  }

  function isFaceTranslucent(translucencyEnabled, alphaByDistance, globe) {
    return (
      translucencyEnabled &&
      (globe.baseColor.alpha < 1.0 ||
        alphaByDistance.nearValue < 1.0 ||
        alphaByDistance.farValue < 1.0)
    );
  }

  function isSunVisibleThroughGlobe(state, scene) {
    // The sun is visible through the globe if the front and back faces are translucent when above ground
    // or if front faces are translucent when below ground
    var frontTranslucent = state._frontFaceTranslucent;
    var backTranslucent = state._backFaceTranslucent;
    return frontTranslucent && (scene.cameraUnderground || backTranslucent);
  }

  function isEnvironmentVisible(state, scene) {
    // The environment is visible if the camera is above ground or underground with translucency
    return !scene.cameraUnderground || state._frontFaceTranslucent;
  }

  function useDepthPlane(state, scene) {
    // Use the depth plane when the camera is above ground and the globe is opaque
    return !scene.cameraUnderground && !state._frontFaceTranslucent;
  }

  function requiresManualDepthTest(state, scene, globe) {
    return (
      state._frontFaceTranslucent &&
      !state._backFaceTranslucent &&
      !globe.depthTestAgainstTerrain &&
      scene.mode !== SceneMode$1.SCENE2D &&
      scene.context.depthTexture
    );
  }

  function getNumberOfTextureUniforms(state) {
    var numberOfTextureUniforms = 0;

    if (state._frontFaceTranslucent) {
      ++numberOfTextureUniforms; // classification texture
    }

    if (state._requiresManualDepthTest) {
      ++numberOfTextureUniforms; // czm_globeDepthTexture for manual depth testing
    }

    return numberOfTextureUniforms;
  }

  function gatherDerivedCommandRequirements(state, scene) {
    state._derivedCommandsLength = getDerivedCommandTypes(
      state,
      scene,
      false,
      false,
      state._derivedCommandTypes
    );

    state._derivedBlendCommandsLength = getDerivedCommandTypes(
      state,
      scene,
      true,
      false,
      state._derivedBlendCommandTypes
    );

    state._derivedPickCommandsLength = getDerivedCommandTypes(
      state,
      scene,
      false,
      true,
      state._derivedPickCommandTypes
    );

    var i;

    var derivedCommandKey = 0;
    for (i = 0; i < state._derivedCommandsLength; ++i) {
      derivedCommandKey |= 1 << state._derivedCommandTypes[i];
    }
    for (i = 0; i < state._derivedBlendCommandsLength; ++i) {
      derivedCommandKey |= 1 << state._derivedBlendCommandTypes[i];
    }
    for (i = 0; i < state._derivedPickCommandsLength; ++i) {
      derivedCommandKey |= 1 << state._derivedPickCommandTypes[i];
    }

    var derivedCommandsToUpdateLength = 0;
    for (i = 0; i < derivedCommandsMaximumLength; ++i) {
      if ((derivedCommandKey & (1 << i)) > 0) {
        state._derivedCommandTypesToUpdate[derivedCommandsToUpdateLength++] = i;
      }
    }
    state._derivedCommandsToUpdateLength = derivedCommandsToUpdateLength;

    var derivedCommandsDirty = derivedCommandKey !== state._derivedCommandKey;
    state._derivedCommandKey = derivedCommandKey;
    state._derivedCommandsDirty = derivedCommandsDirty;

    if (!defined(state._derivedCommandPacks) && state._frontFaceTranslucent) {
      state._derivedCommandPacks = createDerivedCommandPacks();
    }
  }

  function getDerivedCommandTypes(
    state,
    scene,
    isBlendCommand,
    isPickCommand,
    types
  ) {
    var length = 0;

    var frontTranslucent = state._frontFaceTranslucent;
    var backTranslucent = state._backFaceTranslucent;

    if (!frontTranslucent) {
      // Don't use derived commands if the globe is opaque
      return length;
    }

    var cameraUnderground = scene.cameraUnderground;
    var requiresManualDepthTest = state._requiresManualDepthTest;

    var translucentFrontFaceCommandType = isPickCommand
      ? DerivedCommandType.PICK_FRONT_FACE
      : requiresManualDepthTest
      ? DerivedCommandType.TRANSLUCENT_FRONT_FACE_MANUAL_DEPTH_TEST
      : DerivedCommandType.TRANSLUCENT_FRONT_FACE;

    var translucentBackFaceCommandType = isPickCommand
      ? DerivedCommandType.PICK_BACK_FACE
      : requiresManualDepthTest
      ? DerivedCommandType.TRANSLUCENT_BACK_FACE_MANUAL_DEPTH_TEST
      : DerivedCommandType.TRANSLUCENT_BACK_FACE;

    if (scene.mode === SceneMode$1.SCENE2D) {
      types[length++] = DerivedCommandType.DEPTH_ONLY_FRONT_FACE;
      types[length++] = translucentFrontFaceCommandType;
      return length;
    }

    if (backTranslucent) {
      // Push depth-only command for classification. Blend commands do not need to write depth.
      // Push translucent commands for front and back faces.
      if (!isBlendCommand) {
        types[length++] = DerivedCommandType.DEPTH_ONLY_FRONT_AND_BACK_FACE;
      }
      if (cameraUnderground) {
        types[length++] = translucentFrontFaceCommandType;
        types[length++] = translucentBackFaceCommandType;
      } else {
        types[length++] = translucentBackFaceCommandType;
        types[length++] = translucentFrontFaceCommandType;
      }
    } else {
      // Push opaque command for the face that appears in back.
      // Push depth-only command and translucent command for the face that appears in front.
      // eslint-disable-next-line no-lonely-if
      if (cameraUnderground) {
        if (!isBlendCommand) {
          types[length++] = DerivedCommandType.DEPTH_ONLY_BACK_FACE;
        }
        types[length++] = DerivedCommandType.OPAQUE_FRONT_FACE;
        types[length++] = translucentBackFaceCommandType;
      } else {
        if (!isBlendCommand) {
          types[length++] = DerivedCommandType.DEPTH_ONLY_FRONT_FACE;
        }
        types[length++] = DerivedCommandType.OPAQUE_BACK_FACE;
        types[length++] = translucentFrontFaceCommandType;
      }
    }

    return length;
  }

  function removeDefine(defines, defineToRemove) {
    var index = defines.indexOf(defineToRemove);
    if (index > -1) {
      defines.splice(index, 1);
    }
  }

  function hasDefine(defines, define) {
    return defines.indexOf(define) > -1;
  }

  function getOpaqueFrontFaceShaderProgram(vs, fs) {
    removeDefine(vs.defines, "TRANSLUCENT");
    removeDefine(fs.defines, "TRANSLUCENT");
  }

  function getOpaqueBackFaceShaderProgram(vs, fs) {
    removeDefine(vs.defines, "GROUND_ATMOSPHERE");
    removeDefine(fs.defines, "GROUND_ATMOSPHERE");
    removeDefine(vs.defines, "FOG");
    removeDefine(fs.defines, "FOG");
    removeDefine(vs.defines, "TRANSLUCENT");
    removeDefine(fs.defines, "TRANSLUCENT");
  }

  function getDepthOnlyShaderProgram$1(vs, fs) {
    if (
      hasDefine(fs.defines, "TILE_LIMIT_RECTANGLE") ||
      hasDefine(fs.defines, "ENABLE_CLIPPING_PLANES")
    ) {
      // Need to execute the full shader if discard is called
      return;
    }

    var depthOnlyShader =
      "void main() \n" + "{ \n" + "    gl_FragColor = vec4(1.0); \n" + "} \n";

    fs.sources = [depthOnlyShader];
  }

  function getTranslucentShaderProgram(vs, fs) {
    var sources = fs.sources;
    var length = sources.length;
    for (var i = 0; i < length; ++i) {
      sources[i] = ShaderSource.replaceMain(
        sources[i],
        "czm_globe_translucency_main"
      );
    }

    var globeTranslucencyMain =
      "\n\n" +
      "uniform sampler2D u_classificationTexture; \n" +
      "void main() \n" +
      "{ \n" +
      "    vec2 st = gl_FragCoord.xy / czm_viewport.zw; \n" +
      "#ifdef MANUAL_DEPTH_TEST \n" +
      "    float logDepthOrDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, st)); \n" +
      "    if (logDepthOrDepth != 0.0) \n" +
      "    { \n" +
      "        vec4 eyeCoordinate = czm_windowToEyeCoordinates(gl_FragCoord.xy, logDepthOrDepth); \n" +
      "        float depthEC = eyeCoordinate.z / eyeCoordinate.w; \n" +
      "        if (v_positionEC.z < depthEC) \n" +
      "        { \n" +
      "            discard; \n" +
      "        } \n" +
      "    } \n" +
      "#endif \n" +
      "    czm_globe_translucency_main(); \n" +
      "    vec4 classificationColor = texture2D(u_classificationTexture, st); \n" +
      "    if (classificationColor.a > 0.0) \n" +
      "    { \n" +
      "        // Reverse premultiplication process to get the correct composited result of the classification primitives \n" +
      "        classificationColor.rgb /= classificationColor.a; \n" +
      "    } \n" +
      "    gl_FragColor = classificationColor * vec4(classificationColor.aaa, 1.0) + gl_FragColor * (1.0 - classificationColor.a); \n" +
      "} \n";

    sources.push(globeTranslucencyMain);
  }

  function getTranslucentBackFaceShaderProgram(vs, fs) {
    getTranslucentShaderProgram(vs, fs);
    removeDefine(vs.defines, "GROUND_ATMOSPHERE");
    removeDefine(fs.defines, "GROUND_ATMOSPHERE");
    removeDefine(vs.defines, "FOG");
    removeDefine(fs.defines, "FOG");
  }

  function getTranslucentFrontFaceManualDepthTestShaderProgram(vs, fs) {
    getTranslucentShaderProgram(vs, fs);
    vs.defines.push("GENERATE_POSITION");
    fs.defines.push("MANUAL_DEPTH_TEST");
  }

  function getTranslucentBackFaceManualDepthTestShaderProgram(vs, fs) {
    getTranslucentBackFaceShaderProgram(vs, fs);
    vs.defines.push("GENERATE_POSITION");
    fs.defines.push("MANUAL_DEPTH_TEST");
  }

  function getPickShaderProgram$1(vs, fs) {
    var pickShader =
      "uniform sampler2D u_classificationTexture; \n" +
      "void main() \n" +
      "{ \n" +
      "    vec2 st = gl_FragCoord.xy / czm_viewport.zw; \n" +
      "    vec4 pickColor = texture2D(u_classificationTexture, st); \n" +
      "    if (pickColor == vec4(0.0)) \n" +
      "    { \n" +
      "        discard; \n" +
      "    } \n" +
      "    gl_FragColor = pickColor; \n" +
      "} \n";

    fs.sources = [pickShader];
  }

  function getDerivedShaderProgram(
    context,
    shaderProgram,
    derivedShaderProgram,
    shaderProgramDirty,
    getShaderProgramFunction,
    cacheName
  ) {
    if (!defined(getShaderProgramFunction)) {
      return shaderProgram;
    }

    if (!shaderProgramDirty && defined(derivedShaderProgram)) {
      return derivedShaderProgram;
    }

    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      cacheName
    );
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;
      var vs = shaderProgram.vertexShaderSource.clone();
      var fs = shaderProgram.fragmentShaderSource.clone();
      vs.defines = defined(vs.defines) ? vs.defines.slice(0) : [];
      fs.defines = defined(fs.defines) ? fs.defines.slice(0) : [];

      getShaderProgramFunction(vs, fs);

      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        cacheName,
        {
          vertexShaderSource: vs,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  function getOpaqueFrontFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.BACK;
    renderState.cull.enabled = true;
  }

  function getOpaqueBackFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.FRONT;
    renderState.cull.enabled = true;
  }

  function getDepthOnlyFrontFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.BACK;
    renderState.cull.enabled = true;
    renderState.colorMask = {
      red: false,
      green: false,
      blue: false,
      alpha: false,
    };
  }

  function getDepthOnlyBackFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.FRONT;
    renderState.cull.enabled = true;
    renderState.colorMask = {
      red: false,
      green: false,
      blue: false,
      alpha: false,
    };
  }

  function getDepthOnlyFrontAndBackFaceRenderState(renderState) {
    renderState.cull.enabled = false;
    renderState.colorMask = {
      red: false,
      green: false,
      blue: false,
      alpha: false,
    };
  }

  function getTranslucentFrontFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.BACK;
    renderState.cull.enabled = true;
    renderState.depthMask = false;
    renderState.blending = BlendingState$1.ALPHA_BLEND;
  }

  function getTranslucentBackFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.FRONT;
    renderState.cull.enabled = true;
    renderState.depthMask = false;
    renderState.blending = BlendingState$1.ALPHA_BLEND;
  }

  function getPickFrontFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.BACK;
    renderState.cull.enabled = true;
    renderState.blending.enabled = false;
  }

  function getPickBackFaceRenderState(renderState) {
    renderState.cull.face = CullFace$1.FRONT;
    renderState.cull.enabled = true;
    renderState.blending.enabled = false;
  }

  function getDerivedRenderState(
    renderState,
    derivedRenderState,
    renderStateDirty,
    getRenderStateFunction,
    cache
  ) {
    if (!defined(getRenderStateFunction)) {
      return renderState;
    }

    if (!renderStateDirty && defined(derivedRenderState)) {
      return derivedRenderState;
    }

    var cachedRenderState = cache[renderState.id];
    if (!defined(cachedRenderState)) {
      var rs = RenderState.getState(renderState);
      getRenderStateFunction(rs);
      cachedRenderState = RenderState.fromCache(rs);
      cache[renderState.id] = cachedRenderState;
    }

    return cachedRenderState;
  }

  function getTranslucencyUniformMap(state) {
    return {
      u_classificationTexture: function () {
        return state._globeTranslucencyFramebuffer.classificationTexture;
      },
    };
  }

  function getDerivedUniformMap(
    state,
    uniformMap,
    derivedUniformMap,
    uniformMapDirty,
    getDerivedUniformMapFunction
  ) {
    if (!defined(getDerivedUniformMapFunction)) {
      return uniformMap;
    }

    if (!uniformMapDirty && defined(derivedUniformMap)) {
      return derivedUniformMap;
    }

    return combine(uniformMap, getDerivedUniformMapFunction(state), false);
  }

  function DerivedCommandPack(options) {
    this.pass = options.pass;
    this.pickOnly = options.pickOnly;
    this.getShaderProgramFunction = options.getShaderProgramFunction;
    this.getRenderStateFunction = options.getRenderStateFunction;
    this.getUniformMapFunction = options.getUniformMapFunction;
    this.renderStateCache = {};
  }

  function createDerivedCommandPacks() {
    return [
      // opaqueFrontFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.GLOBE,
        pickOnly: false,
        getShaderProgramFunction: getOpaqueFrontFaceShaderProgram,
        getRenderStateFunction: getOpaqueFrontFaceRenderState,
        getUniformMapFunction: undefined,
      }),
      // opaqueBackFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.GLOBE,
        pickOnly: false,
        getShaderProgramFunction: getOpaqueBackFaceShaderProgram,
        getRenderStateFunction: getOpaqueBackFaceRenderState,
        getUniformMapFunction: undefined,
      }),
      // depthOnlyFrontFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.GLOBE,
        pickOnly: false,
        getShaderProgramFunction: getDepthOnlyShaderProgram$1,
        getRenderStateFunction: getDepthOnlyFrontFaceRenderState,
        getUniformMapFunction: undefined,
      }),
      // depthOnlyBackFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.GLOBE,
        pickOnly: false,
        getShaderProgramFunction: getDepthOnlyShaderProgram$1,
        getRenderStateFunction: getDepthOnlyBackFaceRenderState,
        getUniformMapFunction: undefined,
      }),
      // depthOnlyFrontAndBackFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.GLOBE,
        pickOnly: false,
        getShaderProgramFunction: getDepthOnlyShaderProgram$1,
        getRenderStateFunction: getDepthOnlyFrontAndBackFaceRenderState,
        getUniformMapFunction: undefined,
      }),
      // translucentFrontFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.TRANSLUCENT,
        pickOnly: false,
        getShaderProgramFunction: getTranslucentShaderProgram,
        getRenderStateFunction: getTranslucentFrontFaceRenderState,
        getUniformMapFunction: getTranslucencyUniformMap,
      }),
      // translucentBackFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.TRANSLUCENT,
        pickOnly: false,
        getShaderProgramFunction: getTranslucentBackFaceShaderProgram,
        getRenderStateFunction: getTranslucentBackFaceRenderState,
        getUniformMapFunction: getTranslucencyUniformMap,
      }),
      // translucentFrontFaceManualDepthTestCommand
      new DerivedCommandPack({
        pass: Pass$1.TRANSLUCENT,
        pickOnly: false,
        getShaderProgramFunction: getTranslucentFrontFaceManualDepthTestShaderProgram,
        getRenderStateFunction: getTranslucentFrontFaceRenderState,
        getUniformMapFunction: getTranslucencyUniformMap,
      }),
      // translucentBackFaceManualDepthTestCommand
      new DerivedCommandPack({
        pass: Pass$1.TRANSLUCENT,
        pickOnly: false,
        getShaderProgramFunction: getTranslucentBackFaceManualDepthTestShaderProgram,
        getRenderStateFunction: getTranslucentBackFaceRenderState,
        getUniformMapFunction: getTranslucencyUniformMap,
      }),
      // pickFrontFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.TRANSLUCENT,
        pickOnly: true,
        getShaderProgramFunction: getPickShaderProgram$1,
        getRenderStateFunction: getPickFrontFaceRenderState,
        getUniformMapFunction: getTranslucencyUniformMap,
      }),
      // pickBackFaceCommand
      new DerivedCommandPack({
        pass: Pass$1.TRANSLUCENT,
        pickOnly: true,
        getShaderProgramFunction: getPickShaderProgram$1,
        getRenderStateFunction: getPickBackFaceRenderState,
        getUniformMapFunction: getTranslucencyUniformMap,
      }),
    ];
  }

  var derivedCommandNames = new Array(derivedCommandsMaximumLength);
  var derivedCommandPacks = new Array(derivedCommandsMaximumLength);

  GlobeTranslucencyState.prototype.updateDerivedCommands = function (
    command,
    frameState
  ) {
    var derivedCommandTypes = this._derivedCommandTypesToUpdate;
    var derivedCommandsLength = this._derivedCommandsToUpdateLength;

    if (derivedCommandsLength === 0) {
      return;
    }

    for (var i = 0; i < derivedCommandsLength; ++i) {
      derivedCommandPacks[i] = this._derivedCommandPacks[derivedCommandTypes[i]];
      derivedCommandNames[i] = DerivedCommandNames[derivedCommandTypes[i]];
    }

    updateDerivedCommands(
      this,
      command,
      derivedCommandsLength,
      derivedCommandTypes,
      derivedCommandNames,
      derivedCommandPacks,
      frameState
    );
  };

  function updateDerivedCommands(
    state,
    command,
    derivedCommandsLength,
    derivedCommandTypes,
    derivedCommandNames,
    derivedCommandPacks,
    frameState
  ) {
    var derivedCommandsObject = command.derivedCommands.globeTranslucency;
    var derivedCommandsDirty = state._derivedCommandsDirty;

    if (
      command.dirty ||
      !defined(derivedCommandsObject) ||
      derivedCommandsDirty
    ) {
      command.dirty = false;

      if (!defined(derivedCommandsObject)) {
        derivedCommandsObject = {};
        command.derivedCommands.globeTranslucency = derivedCommandsObject;
      }

      var frameNumber = frameState.frameNumber;

      var uniformMapDirtyFrame = defaultValue(
        derivedCommandsObject.uniformMapDirtyFrame,
        0
      );
      var shaderProgramDirtyFrame = defaultValue(
        derivedCommandsObject.shaderProgramDirtyFrame,
        0
      );
      var renderStateDirtyFrame = defaultValue(
        derivedCommandsObject.renderStateDirtyFrame,
        0
      );

      var uniformMapDirty =
        derivedCommandsObject.uniformMap !== command.uniformMap;

      var shaderProgramDirty =
        derivedCommandsObject.shaderProgramId !== command.shaderProgram.id;

      var renderStateDirty =
        derivedCommandsObject.renderStateId !== command.renderState.id;

      if (uniformMapDirty) {
        derivedCommandsObject.uniformMapDirtyFrame = frameNumber;
      }
      if (shaderProgramDirty) {
        derivedCommandsObject.shaderProgramDirtyFrame = frameNumber;
      }
      if (renderStateDirty) {
        derivedCommandsObject.renderStateDirtyFrame = frameNumber;
      }

      derivedCommandsObject.uniformMap = command.uniformMap;
      derivedCommandsObject.shaderProgramId = command.shaderProgram.id;
      derivedCommandsObject.renderStateId = command.renderState.id;

      for (var i = 0; i < derivedCommandsLength; ++i) {
        var derivedCommandPack = derivedCommandPacks[i];
        var derivedCommandType = derivedCommandTypes[i];
        var derivedCommandName = derivedCommandNames[i];
        var derivedCommand = derivedCommandsObject[derivedCommandName];

        var derivedUniformMap;
        var derivedShaderProgram;
        var derivedRenderState;

        if (defined(derivedCommand)) {
          derivedUniformMap = derivedCommand.uniformMap;
          derivedShaderProgram = derivedCommand.shaderProgram;
          derivedRenderState = derivedCommand.renderState;
        } else {
          derivedUniformMap = undefined;
          derivedShaderProgram = undefined;
          derivedRenderState = undefined;
        }

        derivedCommand = DrawCommand.shallowClone(command, derivedCommand);
        derivedCommandsObject[derivedCommandName] = derivedCommand;

        var derivedUniformMapDirtyFrame = defaultValue(
          derivedCommand.derivedCommands.uniformMapDirtyFrame,
          0
        );
        var derivedShaderProgramDirtyFrame = defaultValue(
          derivedCommand.derivedCommands.shaderProgramDirtyFrame,
          0
        );
        var derivedRenderStateDirtyFrame = defaultValue(
          derivedCommand.derivedCommands.renderStateDirtyFrame,
          0
        );

        var derivedUniformMapDirty =
          uniformMapDirty || derivedUniformMapDirtyFrame < uniformMapDirtyFrame;
        var derivedShaderProgramDirty =
          shaderProgramDirty ||
          derivedShaderProgramDirtyFrame < shaderProgramDirtyFrame;
        var derivedRenderStateDirty =
          renderStateDirty ||
          derivedRenderStateDirtyFrame < renderStateDirtyFrame;

        if (derivedUniformMapDirty) {
          derivedCommand.derivedCommands.uniformMapDirtyFrame = frameNumber;
        }
        if (derivedShaderProgramDirty) {
          derivedCommand.derivedCommands.shaderProgramDirtyFrame = frameNumber;
        }
        if (derivedRenderStateDirty) {
          derivedCommand.derivedCommands.renderStateDirtyFrame = frameNumber;
        }

        derivedCommand.derivedCommands.type = derivedCommandType;
        derivedCommand.pass = derivedCommandPack.pass;
        derivedCommand.pickOnly = derivedCommandPack.pickOnly;
        derivedCommand.uniformMap = getDerivedUniformMap(
          state,
          command.uniformMap,
          derivedUniformMap,
          derivedUniformMapDirty,
          derivedCommandPack.getUniformMapFunction
        );
        derivedCommand.shaderProgram = getDerivedShaderProgram(
          frameState.context,
          command.shaderProgram,
          derivedShaderProgram,
          derivedShaderProgramDirty,
          derivedCommandPack.getShaderProgramFunction,
          derivedCommandName
        );
        derivedCommand.renderState = getDerivedRenderState(
          command.renderState,
          derivedRenderState,
          derivedRenderStateDirty,
          derivedCommandPack.getRenderStateFunction,
          derivedCommandPack.renderStateCache
        );
      }
    }
  }

  GlobeTranslucencyState.prototype.pushDerivedCommands = function (
    command,
    isBlendCommand,
    frameState
  ) {
    var picking = frameState.passes.pick;
    if (picking && isBlendCommand) {
      // No need to push blend commands in the pick pass
      return;
    }

    var derivedCommandTypes = this._derivedCommandTypes;
    var derivedCommandsLength = this._derivedCommandsLength;

    if (picking) {
      derivedCommandTypes = this._derivedPickCommandTypes;
      derivedCommandsLength = this._derivedPickCommandsLength;
    } else if (isBlendCommand) {
      derivedCommandTypes = this._derivedBlendCommandTypes;
      derivedCommandsLength = this._derivedBlendCommandsLength;
    }

    if (derivedCommandsLength === 0) {
      // No derived commands to push so just push the globe command
      frameState.commandList.push(command);
      return;
    }

    // Push derived commands
    var derivedCommands = command.derivedCommands.globeTranslucency;
    for (var i = 0; i < derivedCommandsLength; ++i) {
      var derivedCommandName = DerivedCommandNames[derivedCommandTypes[i]];
      frameState.commandList.push(derivedCommands[derivedCommandName]);
    }
  };

  function executeCommandsMatchingType(
    commands,
    commandsLength,
    executeCommandFunction,
    scene,
    context,
    passState,
    types
  ) {
    for (var i = 0; i < commandsLength; ++i) {
      var command = commands[i];
      var type = command.derivedCommands.type;
      if (!defined(types) || types.indexOf(type) > -1) {
        executeCommandFunction(command, scene, context, passState);
      }
    }
  }

  function executeCommands(
    commands,
    commandsLength,
    executeCommandFunction,
    scene,
    context,
    passState
  ) {
    for (var i = 0; i < commandsLength; ++i) {
      executeCommandFunction(commands[i], scene, context, passState);
    }
  }

  var opaqueTypes = [
    DerivedCommandType.OPAQUE_FRONT_FACE,
    DerivedCommandType.OPAQUE_BACK_FACE,
  ];
  var depthOnlyTypes = [
    DerivedCommandType.DEPTH_ONLY_FRONT_FACE,
    DerivedCommandType.DEPTH_ONLY_BACK_FACE,
    DerivedCommandType.DEPTH_ONLY_FRONT_AND_BACK_FACE,
  ];

  GlobeTranslucencyState.prototype.executeGlobeCommands = function (
    frustumCommands,
    executeCommandFunction,
    globeTranslucencyFramebuffer,
    scene,
    passState
  ) {
    var context = scene.context;
    var globeCommands = frustumCommands.commands[Pass$1.GLOBE];
    var globeCommandsLength = frustumCommands.indices[Pass$1.GLOBE];

    if (globeCommandsLength === 0) {
      return;
    }

    this._globeTranslucencyFramebuffer = globeTranslucencyFramebuffer;
    globeTranslucencyFramebuffer.clearClassification(context, passState);

    // Render opaque commands like normal
    executeCommandsMatchingType(
      globeCommands,
      globeCommandsLength,
      executeCommandFunction,
      scene,
      context,
      passState,
      opaqueTypes
    );
  };

  GlobeTranslucencyState.prototype.executeGlobeClassificationCommands = function (
    frustumCommands,
    executeCommandFunction,
    globeTranslucencyFramebuffer,
    scene,
    passState
  ) {
    var context = scene.context;
    var globeCommands = frustumCommands.commands[Pass$1.GLOBE];
    var globeCommandsLength = frustumCommands.indices[Pass$1.GLOBE];
    var classificationCommands =
      frustumCommands.commands[Pass$1.TERRAIN_CLASSIFICATION];
    var classificationCommandsLength =
      frustumCommands.indices[Pass$1.TERRAIN_CLASSIFICATION];

    if (globeCommandsLength === 0 || classificationCommandsLength === 0) {
      return;
    }

    var frontTranslucent = this._frontFaceTranslucent;
    var backTranslucent = this._backFaceTranslucent;

    if (!frontTranslucent || !backTranslucent) {
      // Render classification on opaque faces like normal
      executeCommands(
        classificationCommands,
        classificationCommandsLength,
        executeCommandFunction,
        scene,
        context,
        passState
      );
    }

    if (!frontTranslucent && !backTranslucent) {
      // No translucent commands to render. Skip translucent classification.
      return;
    }

    this._globeTranslucencyFramebuffer = globeTranslucencyFramebuffer;

    var originalGlobeDepthTexture = context.uniformState.globeDepthTexture;
    var originalFramebuffer = passState.framebuffer;

    // Render to internal framebuffer and get the first depth peel
    passState.framebuffer =
      globeTranslucencyFramebuffer.classificationFramebuffer;

    executeCommandsMatchingType(
      globeCommands,
      globeCommandsLength,
      executeCommandFunction,
      scene,
      context,
      passState,
      depthOnlyTypes
    );

    if (context.depthTexture) {
      // Pack depth into separate texture for ground polylines and textured ground primitives
      var packedDepthTexture = globeTranslucencyFramebuffer.packDepth(
        context,
        passState
      );
      context.uniformState.globeDepthTexture = packedDepthTexture;
    }

    // Render classification on translucent faces
    executeCommands(
      classificationCommands,
      classificationCommandsLength,
      executeCommandFunction,
      scene,
      context,
      passState
    );

    // Unset temporary state
    context.uniformState.globeDepthTexture = originalGlobeDepthTexture;
    passState.framebuffer = originalFramebuffer;
  };

  /**
   * @private
   */
  function GoogleEarthEnterpriseDiscardPolicy() {
    this._image = new Image();
  }

  /**
   * Determines if the discard policy is ready to process images.
   * @returns {Boolean} True if the discard policy is ready to process images; otherwise, false.
   */
  GoogleEarthEnterpriseDiscardPolicy.prototype.isReady = function () {
    return true;
  };

  /**
   * Given a tile image, decide whether to discard that image.
   *
   * @param {HTMLImageElement} image An image to test.
   * @returns {Boolean} True if the image should be discarded; otherwise, false.
   */
  GoogleEarthEnterpriseDiscardPolicy.prototype.shouldDiscardImage = function (
    image
  ) {
    return image === this._image;
  };

  /**
   * @typedef {Object} GoogleEarthEnterpriseImageryProvider.ConstructorOptions
   *
   * Initialization options for the GoogleEarthEnterpriseImageryProvider constructor
   *
   * @property {Resource|String} url The url of the Google Earth Enterprise server hosting the imagery.
   * @property {GoogleEarthEnterpriseMetadata} metadata A metadata object that can be used to share metadata requests with a GoogleEarthEnterpriseTerrainProvider.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @property {TileDiscardPolicy} [tileDiscardPolicy] The policy that determines if a tile
   *        is invalid and should be discarded. If this value is not specified, a default
   *        is to discard tiles that fail to download.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * Provides tiled imagery using the Google Earth Enterprise REST API.
   *
   * Notes: This provider is for use with the 3D Earth API of Google Earth Enterprise,
   *        {@link GoogleEarthEnterpriseMapsProvider} should be used with 2D Maps API.
   *
   * @alias GoogleEarthEnterpriseImageryProvider
   * @constructor
   *
   * @param {GoogleEarthEnterpriseImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @see GoogleEarthEnterpriseTerrainProvider
   * @see ArcGisMapServerImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   *
   * @example
   * var geeMetadata = new GoogleEarthEnterpriseMetadata('http://www.earthenterprise.org/3d');
   * var gee = new Cesium.GoogleEarthEnterpriseImageryProvider({
   *     metadata : geeMetadata
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  function GoogleEarthEnterpriseImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!(defined(options.url) || defined(options.metadata))) {
      throw new DeveloperError("options.url or options.metadata is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var metadata;
    if (defined(options.metadata)) {
      metadata = options.metadata;
    } else {
      var resource = Resource.createIfNeeded(options.url);
      metadata = new GoogleEarthEnterpriseMetadata(resource);
    }
    this._metadata = metadata;
    this._tileDiscardPolicy = options.tileDiscardPolicy;

    this._tilingScheme = new GeographicTilingScheme({
      numberOfLevelZeroTilesX: 2,
      numberOfLevelZeroTilesY: 2,
      rectangle: new Rectangle(
        -CesiumMath.PI,
        -CesiumMath.PI,
        CesiumMath.PI,
        CesiumMath.PI
      ),
      ellipsoid: options.ellipsoid,
    });

    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    this._tileWidth = 256;
    this._tileHeight = 256;
    this._maximumLevel = 23;

    // Install the default tile discard policy if none has been supplied.
    if (!defined(this._tileDiscardPolicy)) {
      this._tileDiscardPolicy = new GoogleEarthEnterpriseDiscardPolicy();
    }

    this._errorEvent = new Event();

    this._ready = false;
    var that = this;
    var metadataError;
    this._readyPromise = metadata.readyPromise
      .then(function (result) {
        if (!metadata.imageryPresent) {
          var e = new RuntimeError(
            "The server " + metadata.url + " doesn't have imagery"
          );
          metadataError = TileProviderError.handleError(
            metadataError,
            that,
            that._errorEvent,
            e.message,
            undefined,
            undefined,
            undefined,
            e
          );
          return when.reject(e);
        }

        TileProviderError.handleSuccess(metadataError);
        that._ready = result;
        return result;
      })
      .otherwise(function (e) {
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          e.message,
          undefined,
          undefined,
          undefined,
          e
        );
        return when.reject(e);
      });
  }

  Object.defineProperties(GoogleEarthEnterpriseImageryProvider.prototype, {
    /**
     * Gets the name of the Google Earth Enterprise server url hosting the imagery.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._metadata.url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._metadata.proxy;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return 0;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "rectangle must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  Setting this property to false reduces memory usage
     * and texture upload time.
     * @memberof GoogleEarthEnterpriseImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return false;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  GoogleEarthEnterpriseImageryProvider.prototype.getTileCredits = function (
    x,
    y,
    level
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "getTileCredits must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    var metadata = this._metadata;
    var info = metadata.getTileInformation(x, y, level);
    if (defined(info)) {
      var credit = metadata.providers[info.imageryProvider];
      if (defined(credit)) {
        return [credit];
      }
    }

    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  GoogleEarthEnterpriseImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    var invalidImage = this._tileDiscardPolicy._image; // Empty image or undefined depending on discard policy
    var metadata = this._metadata;
    var quadKey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
    var info = metadata.getTileInformation(x, y, level);
    if (!defined(info)) {
      if (metadata.isValid(quadKey)) {
        var metadataRequest = new Request({
          throttle: request.throttle,
          throttleByServer: request.throttleByServer,
          type: request.type,
          priorityFunction: request.priorityFunction,
        });
        metadata.populateSubtree(x, y, level, metadataRequest);
        return undefined; // No metadata so return undefined so we can be loaded later
      }
      return invalidImage; // Image doesn't exist
    }

    if (!info.hasImagery()) {
      // Already have info and there isn't any imagery here
      return invalidImage;
    }
    var promise = buildImageResource$2(
      this,
      info,
      x,
      y,
      level,
      request
    ).fetchArrayBuffer();
    if (!defined(promise)) {
      return undefined; // Throttled
    }

    return promise.then(function (image) {
      decodeGoogleEarthEnterpriseData(metadata.key, image);
      var a = new Uint8Array(image);
      var type;

      var protoImagery = metadata.protoImagery;
      if (!defined(protoImagery) || !protoImagery) {
        type = getImageType(a);
      }

      if (!defined(type) && (!defined(protoImagery) || protoImagery)) {
        var message = decodeEarthImageryPacket(a);
        type = message.imageType;
        a = message.imageData;
      }

      if (!defined(type) || !defined(a)) {
        return invalidImage;
      }

      return loadImageFromTypedArray({
        uint8Array: a,
        format: type,
        flipY: true,
      });
    });
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  GoogleEarthEnterpriseImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  //
  // Functions to handle imagery packets
  //
  function buildImageResource$2(imageryProvider, info, x, y, level, request) {
    var quadKey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
    var version = info.imageryVersion;
    version = defined(version) && version > 0 ? version : 1;

    return imageryProvider._metadata.resource.getDerivedResource({
      url: "flatfile?f1-0" + quadKey + "-i." + version.toString(),
      request: request,
    });
  }

  // Detects if a Uint8Array is a JPEG or PNG
  function getImageType(image) {
    var jpeg = "JFIF";
    if (
      image[6] === jpeg.charCodeAt(0) &&
      image[7] === jpeg.charCodeAt(1) &&
      image[8] === jpeg.charCodeAt(2) &&
      image[9] === jpeg.charCodeAt(3)
    ) {
      return "image/jpeg";
    }

    var png = "PNG";
    if (
      image[1] === png.charCodeAt(0) &&
      image[2] === png.charCodeAt(1) &&
      image[3] === png.charCodeAt(2)
    ) {
      return "image/png";
    }

    return undefined;
  }

  // Decodes an Imagery protobuf into the message
  // Partially generated with the help of protobuf.js static generator
  function decodeEarthImageryPacket(data) {
    var reader = protobuf.Reader.create(data);
    var end = reader.len;
    var message = {};
    while (reader.pos < end) {
      var tag = reader.uint32();
      switch (tag >>> 3) {
        case 1:
          message.imageType = reader.uint32();
          break;
        case 2:
          message.imageData = reader.bytes();
          break;
        case 3:
          message.alphaType = reader.uint32();
          break;
        case 4:
          message.imageAlpha = reader.bytes();
          break;
        case 5:
          var copyrightIds = message.copyrightIds;
          if (!defined(copyrightIds)) {
            copyrightIds = message.copyrightIds = [];
          }
          if ((tag & 7) === 2) {
            var end2 = reader.uint32() + reader.pos;
            while (reader.pos < end2) {
              copyrightIds.push(reader.uint32());
            }
          } else {
            copyrightIds.push(reader.uint32());
          }
          break;
        default:
          reader.skipType(tag & 7);
          break;
      }
    }

    var imageType = message.imageType;
    if (defined(imageType)) {
      switch (imageType) {
        case 0:
          message.imageType = "image/jpeg";
          break;
        case 4:
          message.imageType = "image/png";
          break;
        default:
          throw new RuntimeError(
            "GoogleEarthEnterpriseImageryProvider: Unsupported image type."
          );
      }
    }

    var alphaType = message.alphaType;
    if (defined(alphaType) && alphaType !== 0) {
      console.log(
        "GoogleEarthEnterpriseImageryProvider: External alpha not supported."
      );
      delete message.alphaType;
      delete message.imageAlpha;
    }

    return message;
  }

  /**
   * @typedef {Object} GoogleEarthEnterpriseMapsProvider.ConstructorOptions
   *
   * Initialization options for the GoogleEarthEnterpriseMapsProvider constructor
   *
   * @property {Resource|String} url The url of the Google Earth server hosting the imagery.
   * @property {Number} channel The channel (id) to be used when requesting data from the server.
   *        The channel number can be found by looking at the json file located at:
   *        earth.localdomain/default_map/query?request=Json&vars=geeServerDefs The /default_map path may
   *        differ depending on your Google Earth Enterprise server configuration. Look for the "id" that
   *        is associated with a "ImageryMaps" requestType. There may be more than one id available.
   *        Example:
   *        {
   *          layers: [
   *            {
   *              id: 1002,
   *              requestType: "ImageryMaps"
   *            },
   *            {
   *              id: 1007,
   *              requestType: "VectorMapsRaster"
   *            }
   *          ]
   *        }
   * @property {String} [path="/default_map"] The path of the Google Earth server hosting the imagery.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the Google Earth
   *        Enterprise server, or undefined if there is no limit.
   * @property {TileDiscardPolicy} [tileDiscardPolicy] The policy that determines if a tile
   *        is invalid and should be discarded. To ensure that no tiles are discarded, construct and pass
   *        a {@link NeverTileDiscardPolicy} for this parameter.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   */

  /**
   * Provides tiled imagery using the Google Earth Imagery API.
   *
   * Notes: This imagery provider does not work with the public Google Earth servers. It works with the
   *        Google Earth Enterprise Server.
   *
   *        By default the Google Earth Enterprise server does not set the
   *        {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing} headers. You can either
   *        use a proxy server which adds these headers, or in the /opt/google/gehttpd/conf/gehttpd.conf
   *        and add the 'Header set Access-Control-Allow-Origin "*"' option to the '&lt;Directory /&gt;' and
   *        '&lt;Directory "/opt/google/gehttpd/htdocs"&gt;' directives.
   *
   *        This provider is for use with 2D Maps API as part of Google Earth Enterprise. For 3D Earth API uses, it
   *        is necessary to use {@link GoogleEarthEnterpriseImageryProvider}
   *
   * @alias GoogleEarthEnterpriseMapsProvider
   * @constructor
   *
   * @param {GoogleEarthEnterpriseMapsProvider.ConstructorOptions} options Object describing initialization options
   *
   * @exception {RuntimeError} Could not find layer with channel (id) of <code>options.channel</code>.
   * @exception {RuntimeError} Could not find a version in channel (id) <code>options.channel</code>.
   * @exception {RuntimeError} Unsupported projection <code>data.projection</code>.
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   *
   * @example
   * var google = new Cesium.GoogleEarthEnterpriseMapsProvider({
   *     url : 'https://earth.localdomain',
   *     channel : 1008
   * });
   *
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  function GoogleEarthEnterpriseMapsProvider(options) {
    options = defaultValue(options, {});

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    if (!defined(options.channel)) {
      throw new DeveloperError("options.channel is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default 1.9
     */
    this.defaultGamma = 1.9;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var url = options.url;
    var path = defaultValue(options.path, "/default_map");

    var resource = Resource.createIfNeeded(url).getDerivedResource({
      // We used to just append path to url, so now that we do proper URI resolution, removed the /
      url: path[0] === "/" ? path.substring(1) : path,
    });

    resource.appendForwardSlash();

    this._resource = resource;
    this._url = url;
    this._path = path;
    this._tileDiscardPolicy = options.tileDiscardPolicy;
    this._channel = options.channel;
    this._requestType = "ImageryMaps";
    this._credit = new Credit(
      '<a href="http://www.google.com/enterprise/mapsearth/products/earthenterprise.html"><img src="' +
        GoogleEarthEnterpriseMapsProvider.logoUrl +
        '" title="Google Imagery"/></a>'
    );

    this._tilingScheme = undefined;

    this._version = undefined;

    this._tileWidth = 256;
    this._tileHeight = 256;
    this._maximumLevel = options.maximumLevel;

    this._errorEvent = new Event();

    this._ready = false;
    this._readyPromise = when.defer();

    var metadataResource = resource.getDerivedResource({
      url: "query",
      queryParameters: {
        request: "Json",
        vars: "geeServerDefs",
        is2d: "t",
      },
    });
    var that = this;
    var metadataError;

    function metadataSuccess(text) {
      var data;

      // The Google Earth server sends malformed JSON data currently...
      try {
        // First, try parsing it like normal in case a future version sends correctly formatted JSON
        data = JSON.parse(text);
      } catch (e) {
        // Quote object strings manually, then try parsing again
        data = JSON.parse(
          text.replace(/([\[\{,])[\n\r ]*([A-Za-z0-9]+)[\n\r ]*:/g, '$1"$2":')
        );
      }

      var layer;
      for (var i = 0; i < data.layers.length; i++) {
        if (data.layers[i].id === that._channel) {
          layer = data.layers[i];
          break;
        }
      }

      var message;

      if (!defined(layer)) {
        message =
          "Could not find layer with channel (id) of " + that._channel + ".";
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestMetadata
        );
        throw new RuntimeError(message);
      }

      if (!defined(layer.version)) {
        message =
          "Could not find a version in channel (id) " + that._channel + ".";
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestMetadata
        );
        throw new RuntimeError(message);
      }
      that._version = layer.version;

      if (defined(data.projection) && data.projection === "flat") {
        that._tilingScheme = new GeographicTilingScheme({
          numberOfLevelZeroTilesX: 2,
          numberOfLevelZeroTilesY: 2,
          rectangle: new Rectangle(-Math.PI, -Math.PI, Math.PI, Math.PI),
          ellipsoid: options.ellipsoid,
        });
        // Default to mercator projection when projection is undefined
      } else if (!defined(data.projection) || data.projection === "mercator") {
        that._tilingScheme = new WebMercatorTilingScheme({
          numberOfLevelZeroTilesX: 2,
          numberOfLevelZeroTilesY: 2,
          ellipsoid: options.ellipsoid,
        });
      } else {
        message = "Unsupported projection " + data.projection + ".";
        metadataError = TileProviderError.handleError(
          metadataError,
          that,
          that._errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestMetadata
        );
        throw new RuntimeError(message);
      }

      that._ready = true;
      that._readyPromise.resolve(true);
      TileProviderError.handleSuccess(metadataError);
    }

    function metadataFailure(e) {
      var message =
        "An error occurred while accessing " + metadataResource.url + ".";
      metadataError = TileProviderError.handleError(
        metadataError,
        that,
        that._errorEvent,
        message,
        undefined,
        undefined,
        undefined,
        requestMetadata
      );
      that._readyPromise.reject(new RuntimeError(message));
    }

    function requestMetadata() {
      var metadata = metadataResource.fetchText();
      when(metadata, metadataSuccess, metadataFailure);
    }

    requestMetadata();
  }

  Object.defineProperties(GoogleEarthEnterpriseMapsProvider.prototype, {
    /**
     * Gets the URL of the Google Earth MapServer.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._url;
      },
    },

    /**
     * Gets the url path of the data on the Google Earth server.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {String}
     * @readonly
     */
    path: {
      get: function () {
        return this._path;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the imagery channel (id) currently being used.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Number}
     * @readonly
     */
    channel: {
      get: function () {
        return this._channel;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return 0;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets the version of the data used by this provider.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Number}
     * @readonly
     */
    version: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "version must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._version;
      },
    },

    /**
     * Gets the type of data that is being requested from the provider.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {String}
     * @readonly
     */
    requestType: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "requestType must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._requestType;
      },
    },
    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "rectangle must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof GoogleEarthEnterpriseMapsProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return true;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  GoogleEarthEnterpriseMapsProvider.prototype.getTileCredits = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  GoogleEarthEnterpriseMapsProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    var resource = this._resource.getDerivedResource({
      url: "query",
      request: request,
      queryParameters: {
        request: this._requestType,
        channel: this._channel,
        version: this._version,
        x: x,
        y: y,
        z: level + 1, // Google Earth starts with a zoom level of 1, not 0
      },
    });

    return ImageryProvider.loadImage(this, resource);
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  GoogleEarthEnterpriseMapsProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  GoogleEarthEnterpriseMapsProvider._logoUrl = undefined;

  Object.defineProperties(GoogleEarthEnterpriseMapsProvider, {
    /**
     * Gets or sets the URL to the Google Earth logo for display in the credit.
     * @memberof GoogleEarthEnterpriseMapsProvider
     * @type {String}
     */
    logoUrl: {
      get: function () {
        if (!defined(GoogleEarthEnterpriseMapsProvider._logoUrl)) {
          GoogleEarthEnterpriseMapsProvider._logoUrl = buildModuleUrl(
            "Assets/Images/google_earth_credit.png"
          );
        }
        return GoogleEarthEnterpriseMapsProvider._logoUrl;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');

        GoogleEarthEnterpriseMapsProvider._logoUrl = value;
      },
    },
  });

  var defaultColor$8 = new Color(1.0, 1.0, 1.0, 0.4);
  var defaultGlowColor = new Color(0.0, 1.0, 0.0, 0.05);
  var defaultBackgroundColor$2 = new Color(0.0, 0.5, 0.0, 0.2);

  /**
   * @typedef {Object} GridImageryProvider.ConstructorOptions
   *
   * Initialization options for the GridImageryProvider constructor
   *
   * @param {TilingScheme} [tilingScheme=new GeographicTilingScheme()] The tiling scheme for which to draw tiles.
   * @param {Ellipsoid} [ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   *                    this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   *                    parameter is specified, the WGS84 ellipsoid is used.
   * @param {Number} [cells=8] The number of grids cells.
   * @param {Color} [color=Color(1.0, 1.0, 1.0, 0.4)] The color to draw grid lines.
   * @param {Color} [glowColor=Color(0.0, 1.0, 0.0, 0.05)] The color to draw glow for grid lines.
   * @param {Number} [glowWidth=6] The width of lines used for rendering the line glow effect.
   * @param {Color} [backgroundColor=Color(0.0, 0.5, 0.0, 0.2)] Background fill color.
   * @param {Number} [tileWidth=256] The width of the tile for level-of-detail selection purposes.
   * @param {Number} [tileHeight=256] The height of the tile for level-of-detail selection purposes.
   * @param {Number} [canvasSize=256] The size of the canvas used for rendering.
   */

  /**
   * An {@link ImageryProvider} that draws a wireframe grid on every tile with controllable background and glow.
   * May be useful for custom rendering effects or debugging terrain.
   *
   * @alias GridImageryProvider
   * @constructor
   * @param {GridImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   */
  function GridImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    this._tilingScheme = defined(options.tilingScheme)
      ? options.tilingScheme
      : new GeographicTilingScheme({ ellipsoid: options.ellipsoid });
    this._cells = defaultValue(options.cells, 8);
    this._color = defaultValue(options.color, defaultColor$8);
    this._glowColor = defaultValue(options.glowColor, defaultGlowColor);
    this._glowWidth = defaultValue(options.glowWidth, 6);
    this._backgroundColor = defaultValue(
      options.backgroundColor,
      defaultBackgroundColor$2
    );
    this._errorEvent = new Event();

    this._tileWidth = defaultValue(options.tileWidth, 256);
    this._tileHeight = defaultValue(options.tileHeight, 256);

    // A little larger than tile size so lines are sharper
    // Note: can't be too much difference otherwise texture blowout
    this._canvasSize = defaultValue(options.canvasSize, 256);

    // We only need a single canvas since all tiles will be the same
    this._canvas = this._createGridCanvas();

    this._readyPromise = when.resolve(true);
  }

  Object.defineProperties(GridImageryProvider.prototype, {
    /**
     * Gets the proxy used by this provider.
     * @memberof GridImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._tilingScheme.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof GridImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof GridImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return true;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof GridImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link GridImageryProvider#ready} returns true.
     * @memberof GridImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof GridImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return true;
      },
    },
  });

  /**
   * Draws a grid of lines into a canvas.
   */
  GridImageryProvider.prototype._drawGrid = function (context) {
    var minPixel = 0;
    var maxPixel = this._canvasSize;
    for (var x = 0; x <= this._cells; ++x) {
      var nx = x / this._cells;
      var val = 1 + nx * (maxPixel - 1);

      context.moveTo(val, minPixel);
      context.lineTo(val, maxPixel);
      context.moveTo(minPixel, val);
      context.lineTo(maxPixel, val);
    }
    context.stroke();
  };

  /**
   * Render a grid into a canvas with background and glow
   */
  GridImageryProvider.prototype._createGridCanvas = function () {
    var canvas = document.createElement("canvas");
    canvas.width = this._canvasSize;
    canvas.height = this._canvasSize;
    var minPixel = 0;
    var maxPixel = this._canvasSize;

    var context = canvas.getContext("2d");

    // Fill the background
    var cssBackgroundColor = this._backgroundColor.toCssColorString();
    context.fillStyle = cssBackgroundColor;
    context.fillRect(minPixel, minPixel, maxPixel, maxPixel);

    // Glow for grid lines
    var cssGlowColor = this._glowColor.toCssColorString();
    context.strokeStyle = cssGlowColor;
    // Wide
    context.lineWidth = this._glowWidth;
    context.strokeRect(minPixel, minPixel, maxPixel, maxPixel);
    this._drawGrid(context);
    // Narrow
    context.lineWidth = this._glowWidth * 0.5;
    context.strokeRect(minPixel, minPixel, maxPixel, maxPixel);
    this._drawGrid(context);

    // Grid lines
    var cssColor = this._color.toCssColorString();
    // Border
    context.strokeStyle = cssColor;
    context.lineWidth = 2;
    context.strokeRect(minPixel, minPixel, maxPixel, maxPixel);
    // Inner
    context.lineWidth = 1;
    this._drawGrid(context);

    return canvas;
  };

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  GridImageryProvider.prototype.getTileCredits = function (x, y, level) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link GridImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   */
  GridImageryProvider.prototype.requestImage = function (x, y, level, request) {
    return this._canvas;
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  GridImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  /**
   * @private
   */
  function InvertClassification() {
    this.previousFramebuffer = undefined;
    this._previousFramebuffer = undefined;

    this._texture = undefined;
    this._classifiedTexture = undefined;
    this._depthStencilTexture = undefined;
    this._fbo = undefined;
    this._fboClassified = undefined;

    this._rsUnclassified = undefined;
    this._rsClassified = undefined;

    this._unclassifiedCommand = undefined;
    this._classifiedCommand = undefined;
    this._translucentCommand = undefined;

    this._clearColorCommand = new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 0.0),
      owner: this,
    });
    this._clearCommand = new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 0.0),
      depth: 1.0,
      stencil: 0,
    });

    var that = this;
    this._uniformMap = {
      colorTexture: function () {
        return that._texture;
      },
      depthTexture: function () {
        return that._depthStencilTexture;
      },
      classifiedTexture: function () {
        return that._classifiedTexture;
      },
    };
  }

  Object.defineProperties(InvertClassification.prototype, {
    unclassifiedCommand: {
      get: function () {
        return this._unclassifiedCommand;
      },
    },
  });

  InvertClassification.isTranslucencySupported = function (context) {
    return context.depthTexture && context.fragmentDepth;
  };

  var rsUnclassified = {
    depthMask: false,
    stencilTest: {
      enabled: true,
      frontFunction: StencilFunction$1.EQUAL,
      frontOperation: {
        fail: StencilOperation$1.KEEP,
        zFail: StencilOperation$1.KEEP,
        zPass: StencilOperation$1.KEEP,
      },
      backFunction: StencilFunction$1.NEVER,
      reference: 0,
      mask: StencilConstants$1.CLASSIFICATION_MASK,
    },
    blending: BlendingState$1.ALPHA_BLEND,
  };

  var rsClassified = {
    depthMask: false,
    stencilTest: {
      enabled: true,
      frontFunction: StencilFunction$1.NOT_EQUAL,
      frontOperation: {
        fail: StencilOperation$1.KEEP,
        zFail: StencilOperation$1.KEEP,
        zPass: StencilOperation$1.KEEP,
      },
      backFunction: StencilFunction$1.NEVER,
      reference: 0,
      mask: StencilConstants$1.CLASSIFICATION_MASK,
    },
    blending: BlendingState$1.ALPHA_BLEND,
  };

  // Set the 3D Tiles bit when rendering back into the scene's framebuffer. This is only needed if
  // invert classification does not use the scene's depth-stencil texture, which is the case if the invert
  // classification color is translucent.
  var rsDefault = {
    depthMask: true,
    depthTest: {
      enabled: true,
    },
    stencilTest: StencilConstants$1.setCesium3DTileBit(),
    stencilMask: StencilConstants$1.CESIUM_3D_TILE_MASK,
    blending: BlendingState$1.ALPHA_BLEND,
  };

  var translucentFS =
    "#extension GL_EXT_frag_depth : enable\n" +
    "uniform sampler2D colorTexture;\n" +
    "uniform sampler2D depthTexture;\n" +
    "uniform sampler2D classifiedTexture;\n" +
    "varying vec2 v_textureCoordinates;\n" +
    "void main()\n" +
    "{\n" +
    "    vec4 color = texture2D(colorTexture, v_textureCoordinates);\n" +
    "    if (color.a == 0.0)\n" +
    "    {\n" +
    "        discard;\n" +
    "    }\n" +
    "    bool isClassified = all(equal(texture2D(classifiedTexture, v_textureCoordinates), vec4(0.0)));\n" +
    "#ifdef UNCLASSIFIED\n" +
    "    vec4 highlightColor = czm_invertClassificationColor;\n" +
    "    if (isClassified)\n" +
    "    {\n" +
    "        discard;\n" +
    "    }\n" +
    "#else\n" +
    "    vec4 highlightColor = vec4(1.0);\n" +
    "    if (!isClassified)\n" +
    "    {\n" +
    "        discard;\n" +
    "    }\n" +
    "#endif\n" +
    "    gl_FragColor = color * highlightColor;\n" +
    "    gl_FragDepthEXT = texture2D(depthTexture, v_textureCoordinates).r;\n" +
    "}\n";

  var opaqueFS =
    "uniform sampler2D colorTexture;\n" +
    "varying vec2 v_textureCoordinates;\n" +
    "void main()\n" +
    "{\n" +
    "    vec4 color = texture2D(colorTexture, v_textureCoordinates);\n" +
    "    if (color.a == 0.0)\n" +
    "    {\n" +
    "        discard;\n" +
    "    }\n" +
    "#ifdef UNCLASSIFIED\n" +
    "    gl_FragColor = color * czm_invertClassificationColor;\n" +
    "#else\n" +
    "    gl_FragColor = color;\n" +
    "#endif\n" +
    "}\n";

  InvertClassification.prototype.update = function (context) {
    var texture = this._texture;
    var previousFramebufferChanged =
      !defined(texture) || this.previousFramebuffer !== this._previousFramebuffer;
    this._previousFramebuffer = this.previousFramebuffer;

    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight;

    var textureChanged =
      !defined(texture) || texture.width !== width || texture.height !== height;
    if (textureChanged || previousFramebufferChanged) {
      this._texture = this._texture && this._texture.destroy();
      this._classifiedTexture =
        this._classifiedTexture && this._classifiedTexture.destroy();
      this._depthStencilTexture =
        this._depthStencilTexture && this._depthStencilTexture.destroy();

      this._texture = new Texture({
        context: context,
        width: width,
        height: height,
        pixelFormat: PixelFormat$1.RGBA,
        pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
        sampler: new Sampler({
          wrapS: TextureWrap$1.CLAMP_TO_EDGE,
          wrapT: TextureWrap$1.CLAMP_TO_EDGE,
          minificationFilter: TextureMinificationFilter$1.LINEAR,
          magnificationFilter: TextureMagnificationFilter$1.LINEAR,
        }),
      });

      if (!defined(this._previousFramebuffer)) {
        this._classifiedTexture = new Texture({
          context: context,
          width: width,
          height: height,
          pixelFormat: PixelFormat$1.RGBA,
          pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
          sampler: new Sampler({
            wrapS: TextureWrap$1.CLAMP_TO_EDGE,
            wrapT: TextureWrap$1.CLAMP_TO_EDGE,
            minificationFilter: TextureMinificationFilter$1.LINEAR,
            magnificationFilter: TextureMagnificationFilter$1.LINEAR,
          }),
        });
        this._depthStencilTexture = new Texture({
          context: context,
          width: width,
          height: height,
          pixelFormat: PixelFormat$1.DEPTH_STENCIL,
          pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
        });
      }
    }

    if (!defined(this._fbo) || textureChanged || previousFramebufferChanged) {
      this._fbo = this._fbo && this._fbo.destroy();
      this._fboClassified = this._fboClassified && this._fboClassified.destroy();

      var depthStencilTexture;
      var depthStencilRenderbuffer;
      if (defined(this._previousFramebuffer)) {
        depthStencilTexture = this._previousFramebuffer.depthStencilTexture;
        depthStencilRenderbuffer = this._previousFramebuffer
          .depthStencilRenderbuffer;
      } else {
        depthStencilTexture = this._depthStencilTexture;
      }

      this._fbo = new Framebuffer({
        context: context,
        colorTextures: [this._texture],
        depthStencilTexture: depthStencilTexture,
        depthStencilRenderbuffer: depthStencilRenderbuffer,
        destroyAttachments: false,
      });

      if (!defined(this._previousFramebuffer)) {
        this._fboClassified = new Framebuffer({
          context: context,
          colorTextures: [this._classifiedTexture],
          depthStencilTexture: depthStencilTexture,
          destroyAttachments: false,
        });
      }
    }

    if (!defined(this._rsUnclassified)) {
      this._rsUnclassified = RenderState.fromCache(rsUnclassified);
      this._rsClassified = RenderState.fromCache(rsClassified);
      this._rsDefault = RenderState.fromCache(rsDefault);
    }

    if (!defined(this._unclassifiedCommand) || previousFramebufferChanged) {
      if (defined(this._unclassifiedCommand)) {
        this._unclassifiedCommand.shaderProgram =
          this._unclassifiedCommand.shaderProgram &&
          this._unclassifiedCommand.shaderProgram.destroy();
        this._classifiedCommand.shaderProgram =
          this._classifiedCommand.shaderProgram &&
          this._classifiedCommand.shaderProgram.destroy();
      }

      var fs = defined(this._previousFramebuffer) ? opaqueFS : translucentFS;
      var unclassifiedFSSource = new ShaderSource({
        defines: ["UNCLASSIFIED"],
        sources: [fs],
      });
      var classifiedFSSource = new ShaderSource({
        sources: [fs],
      });
      this._unclassifiedCommand = context.createViewportQuadCommand(
        unclassifiedFSSource,
        {
          renderState: defined(this._previousFramebuffer)
            ? this._rsUnclassified
            : this._rsDefault,
          uniformMap: this._uniformMap,
          owner: this,
        }
      );
      this._classifiedCommand = context.createViewportQuadCommand(
        classifiedFSSource,
        {
          renderState: defined(this._previousFramebuffer)
            ? this._rsClassified
            : this._rsDefault,
          uniformMap: this._uniformMap,
          owner: this,
        }
      );

      if (defined(this._translucentCommand)) {
        this._translucentCommand.shaderProgram =
          this._translucentCommand.shaderProgram &&
          this._translucentCommand.shaderProgram.destroy();
      }
      if (!defined(this._previousFramebuffer)) {
        this._translucentCommand = context.createViewportQuadCommand(
          PassThrough,
          {
            renderState: this._rsUnclassified,
            uniformMap: this._uniformMap,
            owner: this,
          }
        );
      }
    }
  };

  InvertClassification.prototype.clear = function (context, passState) {
    var framebuffer = passState.framebuffer;

    if (defined(this._previousFramebuffer)) {
      passState.framebuffer = this._fbo;
      this._clearColorCommand.execute(context, passState);
    } else {
      passState.framebuffer = this._fbo;
      this._clearCommand.execute(context, passState);
      passState.framebuffer = this._fboClassified;
      this._clearCommand.execute(context, passState);
    }

    passState.framebuffer = framebuffer;
  };

  InvertClassification.prototype.executeClassified = function (
    context,
    passState
  ) {
    if (!defined(this._previousFramebuffer)) {
      var framebuffer = passState.framebuffer;

      passState.framebuffer = this._fboClassified;
      this._translucentCommand.execute(context, passState);

      passState.framebuffer = framebuffer;
    }
    this._classifiedCommand.execute(context, passState);
  };

  InvertClassification.prototype.executeUnclassified = function (
    context,
    passState
  ) {
    this._unclassifiedCommand.execute(context, passState);
  };

  InvertClassification.prototype.isDestroyed = function () {
    return false;
  };

  InvertClassification.prototype.destroy = function () {
    this._fbo = this._fbo && this._fbo.destroy();
    this._texture = this._texture && this._texture.destroy();
    this._depthStencilTexture =
      this._depthStencilTexture && this._depthStencilTexture.destroy();

    if (defined(this._unclassifiedCommand)) {
      this._unclassifiedCommand.shaderProgram =
        this._unclassifiedCommand.shaderProgram &&
        this._unclassifiedCommand.shaderProgram.destroy();
      this._classifiedCommand.shaderProgram =
        this._classifiedCommand.shaderProgram &&
        this._classifiedCommand.shaderProgram.destroy();
    }

    return destroyObject(this);
  };

  var templateRegex = /{[^}]+}/g;

  var tags = {
    x: xTag,
    y: yTag,
    z: zTag,
    s: sTag,
    reverseX: reverseXTag,
    reverseY: reverseYTag,
    reverseZ: reverseZTag,
    westDegrees: westDegreesTag,
    southDegrees: southDegreesTag,
    eastDegrees: eastDegreesTag,
    northDegrees: northDegreesTag,
    westProjected: westProjectedTag,
    southProjected: southProjectedTag,
    eastProjected: eastProjectedTag,
    northProjected: northProjectedTag,
    width: widthTag,
    height: heightTag,
  };

  var pickFeaturesTags = combine(tags, {
    i: iTag,
    j: jTag,
    reverseI: reverseITag,
    reverseJ: reverseJTag,
    longitudeDegrees: longitudeDegreesTag,
    latitudeDegrees: latitudeDegreesTag,
    longitudeProjected: longitudeProjectedTag,
    latitudeProjected: latitudeProjectedTag,
    format: formatTag,
  });

  /**
   * @typedef {Object} UrlTemplateImageryProvider.ConstructorOptions
   *
   * Initialization options for the UrlTemplateImageryProvider constructor
   *
   * @property {Promise.<Object>|Object} [options] Object with the following properties:
   * @property {Resource|String} url  The URL template to use to request tiles.  It has the following keywords:
   * <ul>
   *     <li><code>{z}</code>: The level of the tile in the tiling scheme.  Level zero is the root of the quadtree pyramid.</li>
   *     <li><code>{x}</code>: The tile X coordinate in the tiling scheme, where 0 is the Westernmost tile.</li>
   *     <li><code>{y}</code>: The tile Y coordinate in the tiling scheme, where 0 is the Northernmost tile.</li>
   *     <li><code>{s}</code>: One of the available subdomains, used to overcome browser limits on the number of simultaneous requests per host.</li>
   *     <li><code>{reverseX}</code>: The tile X coordinate in the tiling scheme, where 0 is the Easternmost tile.</li>
   *     <li><code>{reverseY}</code>: The tile Y coordinate in the tiling scheme, where 0 is the Southernmost tile.</li>
   *     <li><code>{reverseZ}</code>: The level of the tile in the tiling scheme, where level zero is the maximum level of the quadtree pyramid.  In order to use reverseZ, maximumLevel must be defined.</li>
   *     <li><code>{westDegrees}</code>: The Western edge of the tile in geodetic degrees.</li>
   *     <li><code>{southDegrees}</code>: The Southern edge of the tile in geodetic degrees.</li>
   *     <li><code>{eastDegrees}</code>: The Eastern edge of the tile in geodetic degrees.</li>
   *     <li><code>{northDegrees}</code>: The Northern edge of the tile in geodetic degrees.</li>
   *     <li><code>{westProjected}</code>: The Western edge of the tile in projected coordinates of the tiling scheme.</li>
   *     <li><code>{southProjected}</code>: The Southern edge of the tile in projected coordinates of the tiling scheme.</li>
   *     <li><code>{eastProjected}</code>: The Eastern edge of the tile in projected coordinates of the tiling scheme.</li>
   *     <li><code>{northProjected}</code>: The Northern edge of the tile in projected coordinates of the tiling scheme.</li>
   *     <li><code>{width}</code>: The width of each tile in pixels.</li>
   *     <li><code>{height}</code>: The height of each tile in pixels.</li>
   * </ul>
   * @property {Resource|String} [pickFeaturesUrl] The URL template to use to pick features.  If this property is not specified,
   *                 {@link UrlTemplateImageryProvider#pickFeatures} will immediately returned undefined, indicating no
   *                 features picked.  The URL template supports all of the keywords supported by the <code>url</code>
   *                 parameter, plus the following:
   * <ul>
   *     <li><code>{i}</code>: The pixel column (horizontal coordinate) of the picked position, where the Westernmost pixel is 0.</li>
   *     <li><code>{j}</code>: The pixel row (vertical coordinate) of the picked position, where the Northernmost pixel is 0.</li>
   *     <li><code>{reverseI}</code>: The pixel column (horizontal coordinate) of the picked position, where the Easternmost pixel is 0.</li>
   *     <li><code>{reverseJ}</code>: The pixel row (vertical coordinate) of the picked position, where the Southernmost pixel is 0.</li>
   *     <li><code>{longitudeDegrees}</code>: The longitude of the picked position in degrees.</li>
   *     <li><code>{latitudeDegrees}</code>: The latitude of the picked position in degrees.</li>
   *     <li><code>{longitudeProjected}</code>: The longitude of the picked position in the projected coordinates of the tiling scheme.</li>
   *     <li><code>{latitudeProjected}</code>: The latitude of the picked position in the projected coordinates of the tiling scheme.</li>
   *     <li><code>{format}</code>: The format in which to get feature information, as specified in the {@link GetFeatureInfoFormat}.</li>
   * </ul>
   * @property {Object} [urlSchemeZeroPadding] Gets the URL scheme zero padding for each tile coordinate. The format is '000' where
   * each coordinate will be padded on the left with zeros to match the width of the passed string of zeros. e.g. Setting:
   * urlSchemeZeroPadding : { '{x}' : '0000'}
   * will cause an 'x' value of 12 to return the string '0012' for {x} in the generated URL.
   * It the passed object has the following keywords:
   * <ul>
   *  <li> <code>{z}</code>: The zero padding for the level of the tile in the tiling scheme.</li>
   *  <li> <code>{x}</code>: The zero padding for the tile X coordinate in the tiling scheme.</li>
   *  <li> <code>{y}</code>: The zero padding for the the tile Y coordinate in the tiling scheme.</li>
   *  <li> <code>{reverseX}</code>: The zero padding for the tile reverseX coordinate in the tiling scheme.</li>
   *  <li> <code>{reverseY}</code>: The zero padding for the tile reverseY coordinate in the tiling scheme.</li>
   *  <li> <code>{reverseZ}</code>: The zero padding for the reverseZ coordinate of the tile in the tiling scheme.</li>
   * </ul>
   * @property {String|String[]} [subdomains='abc'] The subdomains to use for the <code>{s}</code> placeholder in the URL template.
   *                          If this parameter is a single string, each character in the string is a subdomain.  If it is
   *                          an array, each element in the array is a subdomain.
   * @property {Credit|String} [credit=''] A credit for the data source, which is displayed on the canvas.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.  Take care when specifying
   *                 this that the number of tiles at the minimum level is small, such as four or less.  A larger number is likely
   *                 to result in rendering problems.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle, in radians, covered by the image.
   * @property {TilingScheme} [tilingScheme=WebMercatorTilingScheme] The tiling scheme specifying how the ellipsoidal
   * surface is broken into tiles.  If this parameter is not provided, a {@link WebMercatorTilingScheme}
   * is used.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   *                    this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   *                    parameter is specified, the WGS84 ellipsoid is used.
   * @property {Number} [tileWidth=256] Pixel width of image tiles.
   * @property {Number} [tileHeight=256] Pixel height of image tiles.
   * @property {Boolean} [hasAlphaChannel=true] true if the images provided by this imagery provider
   *                  include an alpha channel; otherwise, false.  If this property is false, an alpha channel, if
   *                  present, will be ignored.  If this property is true, any images without an alpha channel will
   *                  be treated as if their alpha is 1.0 everywhere.  When this property is false, memory usage
   *                  and texture upload time are potentially reduced.
   * @property {GetFeatureInfoFormat[]} [getFeatureInfoFormats] The formats in which to get feature information at a
   *                                 specific location when {@link UrlTemplateImageryProvider#pickFeatures} is invoked.  If this
   *                                 parameter is not specified, feature picking is disabled.
   * @property {Boolean} [enablePickFeatures=true] If true, {@link UrlTemplateImageryProvider#pickFeatures} will
   *        request the <code>pickFeaturesUrl</code> and attempt to interpret the features included in the response.  If false,
   *        {@link UrlTemplateImageryProvider#pickFeatures} will immediately return undefined (indicating no pickable
   *        features) without communicating with the server.  Set this property to false if you know your data
   *        source does not support picking features or if you don't want this provider's features to be pickable. Note
   *        that this can be dynamically overridden by modifying the {@link UriTemplateImageryProvider#enablePickFeatures}
   *        property.
   * @property {Object} [customTags] Allow to replace custom keywords in the URL template. The object must have strings as keys and functions as values.
   */

  /**
   * Provides imagery by requesting tiles using a specified URL template.
   *
   * @alias UrlTemplateImageryProvider
   * @constructor
   *
   * @param {UrlTemplateImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @example
   * // Access Natural Earth II imagery, which uses a TMS tiling scheme and Geographic (EPSG:4326) project
   * var tms = new Cesium.UrlTemplateImageryProvider({
   *     url : Cesium.buildModuleUrl('Assets/Textures/NaturalEarthII') + '/{z}/{x}/{reverseY}.jpg',
   *     credit : '© Analytical Graphics, Inc.',
   *     tilingScheme : new Cesium.GeographicTilingScheme(),
   *     maximumLevel : 5
   * });
   * // Access the CartoDB Positron basemap, which uses an OpenStreetMap-like tiling scheme.
   * var positron = new Cesium.UrlTemplateImageryProvider({
   *     url : 'http://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png',
   *     credit : 'Map tiles by CartoDB, under CC BY 3.0. Data by OpenStreetMap, under ODbL.'
   * });
   * // Access a Web Map Service (WMS) server.
   * var wms = new Cesium.UrlTemplateImageryProvider({
   *    url : 'https://programs.communications.gov.au/geoserver/ows?tiled=true&' +
   *          'transparent=true&format=image%2Fpng&exceptions=application%2Fvnd.ogc.se_xml&' +
   *          'styles=&service=WMS&version=1.1.1&request=GetMap&' +
   *          'layers=public%3AMyBroadband_Availability&srs=EPSG%3A3857&' +
   *          'bbox={westProjected}%2C{southProjected}%2C{eastProjected}%2C{northProjected}&' +
   *          'width=256&height=256',
   *    rectangle : Cesium.Rectangle.fromDegrees(96.799393, -43.598214999057824, 153.63925700000001, -9.2159219997013)
   * });
   * // Using custom tags in your template url.
   * var custom = new Cesium.UrlTemplateImageryProvider({
   *    url : 'https://yoururl/{Time}/{z}/{y}/{x}.png',
   *    customTags : {
   *        Time: function(imageryProvider, x, y, level) {
   *            return '20171231'
   *        }
   *    }
   * });
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   */
  function UrlTemplateImageryProvider(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options)) {
      throw new DeveloperError("options is required.");
    }
    if (!when.isPromise(options) && !defined(options.url)) {
      throw new DeveloperError("options is required.");
    }
    //>>includeEnd('debug');

    this._errorEvent = new Event();

    this._resource = undefined;
    this._urlSchemeZeroPadding = undefined;
    this._pickFeaturesResource = undefined;
    this._tileWidth = undefined;
    this._tileHeight = undefined;
    this._maximumLevel = undefined;
    this._minimumLevel = undefined;
    this._tilingScheme = undefined;
    this._rectangle = undefined;
    this._tileDiscardPolicy = undefined;
    this._credit = undefined;
    this._hasAlphaChannel = undefined;
    this._readyPromise = undefined;
    this._tags = undefined;
    this._pickFeaturesTags = undefined;

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    /**
     * Gets or sets a value indicating whether feature picking is enabled.  If true, {@link UrlTemplateImageryProvider#pickFeatures} will
     * request the <code>options.pickFeaturesUrl</code> and attempt to interpret the features included in the response.  If false,
     * {@link UrlTemplateImageryProvider#pickFeatures} will immediately return undefined (indicating no pickable
     * features) without communicating with the server.  Set this property to false if you know your data
     * source does not support picking features or if you don't want this provider's features to be pickable.
     * @type {Boolean}
     * @default true
     */
    this.enablePickFeatures = true;

    this.reinitialize(options);
  }

  Object.defineProperties(UrlTemplateImageryProvider.prototype, {
    /**
     * Gets the URL template to use to request tiles.  It has the following keywords:
     * <ul>
     *  <li> <code>{z}</code>: The level of the tile in the tiling scheme.  Level zero is the root of the quadtree pyramid.</li>
     *  <li> <code>{x}</code>: The tile X coordinate in the tiling scheme, where 0 is the Westernmost tile.</li>
     *  <li> <code>{y}</code>: The tile Y coordinate in the tiling scheme, where 0 is the Northernmost tile.</li>
     *  <li> <code>{s}</code>: One of the available subdomains, used to overcome browser limits on the number of simultaneous requests per host.</li>
     *  <li> <code>{reverseX}</code>: The tile X coordinate in the tiling scheme, where 0 is the Easternmost tile.</li>
     *  <li> <code>{reverseY}</code>: The tile Y coordinate in the tiling scheme, where 0 is the Southernmost tile.</li>
     *  <li> <code>{reverseZ}</code>: The level of the tile in the tiling scheme, where level zero is the maximum level of the quadtree pyramid.  In order to use reverseZ, maximumLevel must be defined.</li>
     *  <li> <code>{westDegrees}</code>: The Western edge of the tile in geodetic degrees.</li>
     *  <li> <code>{southDegrees}</code>: The Southern edge of the tile in geodetic degrees.</li>
     *  <li> <code>{eastDegrees}</code>: The Eastern edge of the tile in geodetic degrees.</li>
     *  <li> <code>{northDegrees}</code>: The Northern edge of the tile in geodetic degrees.</li>
     *  <li> <code>{westProjected}</code>: The Western edge of the tile in projected coordinates of the tiling scheme.</li>
     *  <li> <code>{southProjected}</code>: The Southern edge of the tile in projected coordinates of the tiling scheme.</li>
     *  <li> <code>{eastProjected}</code>: The Eastern edge of the tile in projected coordinates of the tiling scheme.</li>
     *  <li> <code>{northProjected}</code>: The Northern edge of the tile in projected coordinates of the tiling scheme.</li>
     *  <li> <code>{width}</code>: The width of each tile in pixels.</li>
     *  <li> <code>{height}</code>: The height of each tile in pixels.</li>
     * </ul>
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource.url;
      },
    },

    /**
     * Gets the URL scheme zero padding for each tile coordinate. The format is '000' where each coordinate will be padded on
     * the left with zeros to match the width of the passed string of zeros. e.g. Setting:
     * urlSchemeZeroPadding : { '{x}' : '0000'}
     * will cause an 'x' value of 12 to return the string '0012' for {x} in the generated URL.
     * It has the following keywords:
     * <ul>
     *  <li> <code>{z}</code>: The zero padding for the level of the tile in the tiling scheme.</li>
     *  <li> <code>{x}</code>: The zero padding for the tile X coordinate in the tiling scheme.</li>
     *  <li> <code>{y}</code>: The zero padding for the the tile Y coordinate in the tiling scheme.</li>
     *  <li> <code>{reverseX}</code>: The zero padding for the tile reverseX coordinate in the tiling scheme.</li>
     *  <li> <code>{reverseY}</code>: The zero padding for the tile reverseY coordinate in the tiling scheme.</li>
     *  <li> <code>{reverseZ}</code>: The zero padding for the reverseZ coordinate of the tile in the tiling scheme.</li>
     * </ul>
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Object}
     * @readonly
     */
    urlSchemeZeroPadding: {
      get: function () {
        return this._urlSchemeZeroPadding;
      },
    },

    /**
     * Gets the URL template to use to use to pick features.  If this property is not specified,
     * {@link UrlTemplateImageryProvider#pickFeatures} will immediately return undefined, indicating no
     * features picked.  The URL template supports all of the keywords supported by the
     * {@link UrlTemplateImageryProvider#url} property, plus the following:
     * <ul>
     *     <li><code>{i}</code>: The pixel column (horizontal coordinate) of the picked position, where the Westernmost pixel is 0.</li>
     *     <li><code>{j}</code>: The pixel row (vertical coordinate) of the picked position, where the Northernmost pixel is 0.</li>
     *     <li><code>{reverseI}</code>: The pixel column (horizontal coordinate) of the picked position, where the Easternmost pixel is 0.</li>
     *     <li><code>{reverseJ}</code>: The pixel row (vertical coordinate) of the picked position, where the Southernmost pixel is 0.</li>
     *     <li><code>{longitudeDegrees}</code>: The longitude of the picked position in degrees.</li>
     *     <li><code>{latitudeDegrees}</code>: The latitude of the picked position in degrees.</li>
     *     <li><code>{longitudeProjected}</code>: The longitude of the picked position in the projected coordinates of the tiling scheme.</li>
     *     <li><code>{latitudeProjected}</code>: The latitude of the picked position in the projected coordinates of the tiling scheme.</li>
     *     <li><code>{format}</code>: The format in which to get feature information, as specified in the {@link GetFeatureInfoFormat}.</li>
     * </ul>
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    pickFeaturesUrl: {
      get: function () {
        return this._pickFeaturesResource.url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     * @default undefined
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Number}
     * @readonly
     * @default 256
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Number}
     * @readonly
     * @default 256
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested, or undefined if there is no limit.
     * This function should not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     * @default undefined
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Number}
     * @readonly
     * @default 0
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._minimumLevel;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     * @default new WebMercatorTilingScheme()
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     * @default tilingScheme.rectangle
     */
    rectangle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "rectangle must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     * @default undefined
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return defined(this._resource);
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link UrlTemplateImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Credit}
     * @readonly
     * @default undefined
     */
    credit: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "credit must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.  This function should
     * not be called before {@link ImageryProvider#ready} returns true.
     * @memberof UrlTemplateImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     * @default true
     */
    hasAlphaChannel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this.ready) {
          throw new DeveloperError(
            "hasAlphaChannel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._hasAlphaChannel;
      },
    },
  });

  /**
   * Reinitializes this instance.  Reinitializing an instance already in use is supported, but it is not
   * recommended because existing tiles provided by the imagery provider will not be updated.
   *
   * @param {Promise.<Object>|Object} options Any of the options that may be passed to the {@link UrlTemplateImageryProvider} constructor.
   */
  UrlTemplateImageryProvider.prototype.reinitialize = function (options) {
    var that = this;
    that._readyPromise = when(options).then(function (properties) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(properties)) {
        throw new DeveloperError("options is required.");
      }
      if (!defined(properties.url)) {
        throw new DeveloperError("options.url is required.");
      }
      //>>includeEnd('debug');

      var customTags = properties.customTags;
      var allTags = combine(tags, customTags);
      var allPickFeaturesTags = combine(pickFeaturesTags, customTags);
      var resource = Resource.createIfNeeded(properties.url);
      var pickFeaturesResource = Resource.createIfNeeded(
        properties.pickFeaturesUrl
      );

      that.enablePickFeatures = defaultValue(
        properties.enablePickFeatures,
        that.enablePickFeatures
      );
      that._urlSchemeZeroPadding = defaultValue(
        properties.urlSchemeZeroPadding,
        that.urlSchemeZeroPadding
      );
      that._tileDiscardPolicy = properties.tileDiscardPolicy;
      that._getFeatureInfoFormats = properties.getFeatureInfoFormats;

      that._subdomains = properties.subdomains;
      if (Array.isArray(that._subdomains)) {
        that._subdomains = that._subdomains.slice();
      } else if (defined(that._subdomains) && that._subdomains.length > 0) {
        that._subdomains = that._subdomains.split("");
      } else {
        that._subdomains = ["a", "b", "c"];
      }

      that._tileWidth = defaultValue(properties.tileWidth, 256);
      that._tileHeight = defaultValue(properties.tileHeight, 256);
      that._minimumLevel = defaultValue(properties.minimumLevel, 0);
      that._maximumLevel = properties.maximumLevel;
      that._tilingScheme = defaultValue(
        properties.tilingScheme,
        new WebMercatorTilingScheme({ ellipsoid: properties.ellipsoid })
      );
      that._rectangle = defaultValue(
        properties.rectangle,
        that._tilingScheme.rectangle
      );
      that._rectangle = Rectangle.intersection(
        that._rectangle,
        that._tilingScheme.rectangle
      );
      that._hasAlphaChannel = defaultValue(properties.hasAlphaChannel, true);

      var credit = properties.credit;
      if (typeof credit === "string") {
        credit = new Credit(credit);
      }
      that._credit = credit;

      that._resource = resource;
      that._tags = allTags;
      that._pickFeaturesResource = pickFeaturesResource;
      that._pickFeaturesTags = allPickFeaturesTags;

      return true;
    });
  };

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  UrlTemplateImageryProvider.prototype.getTileCredits = function (x, y, level) {
    //>>includeStart('debug', pragmas.debug);
    if (!this.ready) {
      throw new DeveloperError(
        "getTileCredits must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link UrlTemplateImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   */
  UrlTemplateImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this.ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');
    return ImageryProvider.loadImage(
      this,
      buildImageResource$3(this, x, y, level, request)
    );
  };

  /**
   * Asynchronously determines what features, if any, are located at a given longitude and latitude within
   * a tile.  This function should not be called before {@link ImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  UrlTemplateImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this.ready) {
      throw new DeveloperError(
        "pickFeatures must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    if (
      !this.enablePickFeatures ||
      !defined(this._pickFeaturesResource) ||
      this._getFeatureInfoFormats.length === 0
    ) {
      return undefined;
    }

    var formatIndex = 0;

    var that = this;

    function handleResponse(format, data) {
      return format.callback(data);
    }

    function doRequest() {
      if (formatIndex >= that._getFeatureInfoFormats.length) {
        // No valid formats, so no features picked.
        return when([]);
      }

      var format = that._getFeatureInfoFormats[formatIndex];
      var resource = buildPickFeaturesResource(
        that,
        x,
        y,
        level,
        longitude,
        latitude,
        format.format
      );

      ++formatIndex;

      if (format.type === "json") {
        return resource.fetchJson().then(format.callback).otherwise(doRequest);
      } else if (format.type === "xml") {
        return resource.fetchXML().then(format.callback).otherwise(doRequest);
      } else if (format.type === "text" || format.type === "html") {
        return resource.fetchText().then(format.callback).otherwise(doRequest);
      }
      return resource
        .fetch({
          responseType: format.format,
        })
        .then(handleResponse.bind(undefined, format))
        .otherwise(doRequest);
    }

    return doRequest();
  };

  var degreesScratchComputed = false;
  var degreesScratch = new Rectangle();
  var projectedScratchComputed = false;
  var projectedScratch = new Rectangle();

  function buildImageResource$3(imageryProvider, x, y, level, request) {
    degreesScratchComputed = false;
    projectedScratchComputed = false;

    var resource = imageryProvider._resource;
    var url = resource.getUrlComponent(true);
    var allTags = imageryProvider._tags;
    var templateValues = {};

    var match = url.match(templateRegex);
    if (defined(match)) {
      match.forEach(function (tag) {
        var key = tag.substring(1, tag.length - 1); //strip {}
        if (defined(allTags[key])) {
          templateValues[key] = allTags[key](imageryProvider, x, y, level);
        }
      });
    }

    return resource.getDerivedResource({
      request: request,
      templateValues: templateValues,
    });
  }

  var ijScratchComputed = false;
  var ijScratch = new Cartesian2();
  var longitudeLatitudeProjectedScratchComputed = false;

  function buildPickFeaturesResource(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    degreesScratchComputed = false;
    projectedScratchComputed = false;
    ijScratchComputed = false;
    longitudeLatitudeProjectedScratchComputed = false;

    var resource = imageryProvider._pickFeaturesResource;
    var url = resource.getUrlComponent(true);
    var allTags = imageryProvider._pickFeaturesTags;
    var templateValues = {};
    var match = url.match(templateRegex);
    if (defined(match)) {
      match.forEach(function (tag) {
        var key = tag.substring(1, tag.length - 1); //strip {}
        if (defined(allTags[key])) {
          templateValues[key] = allTags[key](
            imageryProvider,
            x,
            y,
            level,
            longitude,
            latitude,
            format
          );
        }
      });
    }

    return resource.getDerivedResource({
      templateValues: templateValues,
    });
  }

  function padWithZerosIfNecessary(imageryProvider, key, value) {
    if (
      imageryProvider &&
      imageryProvider.urlSchemeZeroPadding &&
      imageryProvider.urlSchemeZeroPadding.hasOwnProperty(key)
    ) {
      var paddingTemplate = imageryProvider.urlSchemeZeroPadding[key];
      if (typeof paddingTemplate === "string") {
        var paddingTemplateWidth = paddingTemplate.length;
        if (paddingTemplateWidth > 1) {
          value =
            value.length >= paddingTemplateWidth
              ? value
              : new Array(
                  paddingTemplateWidth - value.toString().length + 1
                ).join("0") + value;
        }
      }
    }
    return value;
  }

  function xTag(imageryProvider, x, y, level) {
    return padWithZerosIfNecessary(imageryProvider, "{x}", x);
  }

  function reverseXTag(imageryProvider, x, y, level) {
    var reverseX =
      imageryProvider.tilingScheme.getNumberOfXTilesAtLevel(level) - x - 1;
    return padWithZerosIfNecessary(imageryProvider, "{reverseX}", reverseX);
  }

  function yTag(imageryProvider, x, y, level) {
    return padWithZerosIfNecessary(imageryProvider, "{y}", y);
  }

  function reverseYTag(imageryProvider, x, y, level) {
    var reverseY =
      imageryProvider.tilingScheme.getNumberOfYTilesAtLevel(level) - y - 1;
    return padWithZerosIfNecessary(imageryProvider, "{reverseY}", reverseY);
  }

  function reverseZTag(imageryProvider, x, y, level) {
    var maximumLevel = imageryProvider.maximumLevel;
    var reverseZ =
      defined(maximumLevel) && level < maximumLevel
        ? maximumLevel - level - 1
        : level;
    return padWithZerosIfNecessary(imageryProvider, "{reverseZ}", reverseZ);
  }

  function zTag(imageryProvider, x, y, level) {
    return padWithZerosIfNecessary(imageryProvider, "{z}", level);
  }

  function sTag(imageryProvider, x, y, level) {
    var index = (x + y + level) % imageryProvider._subdomains.length;
    return imageryProvider._subdomains[index];
  }

  function computeDegrees(imageryProvider, x, y, level) {
    if (degreesScratchComputed) {
      return;
    }

    imageryProvider.tilingScheme.tileXYToRectangle(x, y, level, degreesScratch);
    degreesScratch.west = CesiumMath.toDegrees(degreesScratch.west);
    degreesScratch.south = CesiumMath.toDegrees(degreesScratch.south);
    degreesScratch.east = CesiumMath.toDegrees(degreesScratch.east);
    degreesScratch.north = CesiumMath.toDegrees(degreesScratch.north);

    degreesScratchComputed = true;
  }

  function westDegreesTag(imageryProvider, x, y, level) {
    computeDegrees(imageryProvider, x, y, level);
    return degreesScratch.west;
  }

  function southDegreesTag(imageryProvider, x, y, level) {
    computeDegrees(imageryProvider, x, y, level);
    return degreesScratch.south;
  }

  function eastDegreesTag(imageryProvider, x, y, level) {
    computeDegrees(imageryProvider, x, y, level);
    return degreesScratch.east;
  }

  function northDegreesTag(imageryProvider, x, y, level) {
    computeDegrees(imageryProvider, x, y, level);
    return degreesScratch.north;
  }

  function computeProjected(imageryProvider, x, y, level) {
    if (projectedScratchComputed) {
      return;
    }

    imageryProvider.tilingScheme.tileXYToNativeRectangle(
      x,
      y,
      level,
      projectedScratch
    );

    projectedScratchComputed = true;
  }

  function westProjectedTag(imageryProvider, x, y, level) {
    computeProjected(imageryProvider, x, y, level);
    return projectedScratch.west;
  }

  function southProjectedTag(imageryProvider, x, y, level) {
    computeProjected(imageryProvider, x, y, level);
    return projectedScratch.south;
  }

  function eastProjectedTag(imageryProvider, x, y, level) {
    computeProjected(imageryProvider, x, y, level);
    return projectedScratch.east;
  }

  function northProjectedTag(imageryProvider, x, y, level) {
    computeProjected(imageryProvider, x, y, level);
    return projectedScratch.north;
  }

  function widthTag(imageryProvider, x, y, level) {
    return imageryProvider.tileWidth;
  }

  function heightTag(imageryProvider, x, y, level) {
    return imageryProvider.tileHeight;
  }

  function iTag(imageryProvider, x, y, level, longitude, latitude, format) {
    computeIJ(imageryProvider, x, y, level, longitude, latitude);
    return ijScratch.x;
  }

  function jTag(imageryProvider, x, y, level, longitude, latitude, format) {
    computeIJ(imageryProvider, x, y, level, longitude, latitude);
    return ijScratch.y;
  }

  function reverseITag(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    computeIJ(imageryProvider, x, y, level, longitude, latitude);
    return imageryProvider.tileWidth - ijScratch.x - 1;
  }

  function reverseJTag(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    computeIJ(imageryProvider, x, y, level, longitude, latitude);
    return imageryProvider.tileHeight - ijScratch.y - 1;
  }

  var rectangleScratch$6 = new Rectangle();
  var longitudeLatitudeProjectedScratch = new Cartesian3();

  function computeIJ(imageryProvider, x, y, level, longitude, latitude, format) {
    if (ijScratchComputed) {
      return;
    }

    computeLongitudeLatitudeProjected(
      imageryProvider,
      x,
      y,
      level,
      longitude,
      latitude
    );
    var projected = longitudeLatitudeProjectedScratch;

    var rectangle = imageryProvider.tilingScheme.tileXYToNativeRectangle(
      x,
      y,
      level,
      rectangleScratch$6
    );
    ijScratch.x =
      ((imageryProvider.tileWidth * (projected.x - rectangle.west)) /
        rectangle.width) |
      0;
    ijScratch.y =
      ((imageryProvider.tileHeight * (rectangle.north - projected.y)) /
        rectangle.height) |
      0;
    ijScratchComputed = true;
  }

  function longitudeDegreesTag(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    return CesiumMath.toDegrees(longitude);
  }

  function latitudeDegreesTag(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    return CesiumMath.toDegrees(latitude);
  }

  function longitudeProjectedTag(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    computeLongitudeLatitudeProjected(
      imageryProvider,
      x,
      y,
      level,
      longitude,
      latitude
    );
    return longitudeLatitudeProjectedScratch.x;
  }

  function latitudeProjectedTag(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    computeLongitudeLatitudeProjected(
      imageryProvider,
      x,
      y,
      level,
      longitude,
      latitude
    );
    return longitudeLatitudeProjectedScratch.y;
  }

  var cartographicScratch$4 = new Cartographic();

  function computeLongitudeLatitudeProjected(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    format
  ) {
    if (longitudeLatitudeProjectedScratchComputed) {
      return;
    }

    if (imageryProvider.tilingScheme.projection instanceof GeographicProjection) {
      longitudeLatitudeProjectedScratch.x = CesiumMath.toDegrees(longitude);
      longitudeLatitudeProjectedScratch.y = CesiumMath.toDegrees(latitude);
    } else {
      var cartographic = cartographicScratch$4;
      cartographic.longitude = longitude;
      cartographic.latitude = latitude;
      imageryProvider.tilingScheme.projection.project(
        cartographic,
        longitudeLatitudeProjectedScratch
      );
    }

    longitudeLatitudeProjectedScratchComputed = true;
  }

  function formatTag(imageryProvider, x, y, level, longitude, latitude, format) {
    return format;
  }

  /**
   * @typedef {Object} TileMapServiceImageryProvider.ConstructorOptions
   *
   * Initialization options for the TileMapServiceImageryProvider constructor
   *
   * @property {Resource|String|Promise<Resource>|Promise<String>} [url='.'] Path to image tiles on server.
   * @property {String} [fileExtension='png'] The file extension for images on the server.
   * @property {Credit|String} [credit=''] A credit for the data source, which is displayed on the canvas.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.  Take care when specifying
   *                 this that the number of tiles at the minimum level is small, such as four or less.  A larger number is likely
   *                 to result in rendering problems.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle, in radians, covered by the image.
   * @property {TilingScheme} [tilingScheme] The tiling scheme specifying how the ellipsoidal
   * surface is broken into tiles.  If this parameter is not provided, a {@link WebMercatorTilingScheme}
   * is used.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   *                    this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   *                    parameter is specified, the WGS84 ellipsoid is used.
   * @property {Number} [tileWidth=256] Pixel width of image tiles.
   * @property {Number} [tileHeight=256] Pixel height of image tiles.
   * @property {Boolean} [flipXY] Older versions of gdal2tiles.py flipped X and Y values in tilemapresource.xml.
   * Specifying this option will do the same, allowing for loading of these incorrect tilesets.
   */

  /**
   * An imagery provider that provides tiled imagery as generated by
   * {@link http://www.maptiler.org/|MapTiler}, {@link http://www.klokan.cz/projects/gdal2tiles/|GDAL2Tiles}, etc.
   *
   * @alias TileMapServiceImageryProvider
   * @constructor
   * @extends UrlTemplateImageryProvider
   *
   * @param {TileMapServiceImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   * @example
   * var tms = new Cesium.TileMapServiceImageryProvider({
   *    url : '../images/cesium_maptiler/Cesium_Logo_Color',
   *    fileExtension: 'png',
   *    maximumLevel: 4,
   *    rectangle: new Cesium.Rectangle(
   *        Cesium.Math.toRadians(-120.0),
   *        Cesium.Math.toRadians(20.0),
   *        Cesium.Math.toRadians(-60.0),
   *        Cesium.Math.toRadians(40.0))
   * });
   */
  function TileMapServiceImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    //>>includeEnd('debug');

    var deferred = when.defer();
    UrlTemplateImageryProvider.call(this, deferred.promise);

    this._tmsResource = undefined;
    this._xmlResource = undefined;
    this._options = options;
    this._deferred = deferred;
    this._metadataError = undefined;

    this._metadataSuccess = this._metadataSuccess.bind(this);
    this._metadataFailure = this._metadataFailure.bind(this);
    this._requestMetadata = this._requestMetadata.bind(this);

    var resource;
    var that = this;
    when(options.url)
      .then(function (url) {
        resource = Resource.createIfNeeded(url);
        resource.appendForwardSlash();

        that._tmsResource = resource;
        that._xmlResource = resource.getDerivedResource({
          url: "tilemapresource.xml",
        });

        that._requestMetadata();
      })
      .otherwise(function (e) {
        deferred.reject(e);
      });
  }

  if (defined(Object.create)) {
    TileMapServiceImageryProvider.prototype = Object.create(
      UrlTemplateImageryProvider.prototype
    );
    TileMapServiceImageryProvider.prototype.constructor = TileMapServiceImageryProvider;
  }

  TileMapServiceImageryProvider.prototype._requestMetadata = function () {
    // Try to load remaining parameters from XML
    this._xmlResource
      .fetchXML()
      .then(this._metadataSuccess)
      .otherwise(this._metadataFailure);
  };

  /**
   * Mutates the properties of a given rectangle so it does not extend outside of the given tiling scheme's rectangle
   * @private
   */
  function confineRectangleToTilingScheme(rectangle, tilingScheme) {
    if (rectangle.west < tilingScheme.rectangle.west) {
      rectangle.west = tilingScheme.rectangle.west;
    }
    if (rectangle.east > tilingScheme.rectangle.east) {
      rectangle.east = tilingScheme.rectangle.east;
    }
    if (rectangle.south < tilingScheme.rectangle.south) {
      rectangle.south = tilingScheme.rectangle.south;
    }
    if (rectangle.north > tilingScheme.rectangle.north) {
      rectangle.north = tilingScheme.rectangle.north;
    }
    return rectangle;
  }

  function calculateSafeMinimumDetailLevel(
    tilingScheme,
    rectangle,
    minimumLevel
  ) {
    // Check the number of tiles at the minimum level.  If it's more than four,
    // try requesting the lower levels anyway, because starting at the higher minimum
    // level will cause too many tiles to be downloaded and rendered.
    var swTile = tilingScheme.positionToTileXY(
      Rectangle.southwest(rectangle),
      minimumLevel
    );
    var neTile = tilingScheme.positionToTileXY(
      Rectangle.northeast(rectangle),
      minimumLevel
    );
    var tileCount =
      (Math.abs(neTile.x - swTile.x) + 1) * (Math.abs(neTile.y - swTile.y) + 1);
    if (tileCount > 4) {
      return 0;
    }
    return minimumLevel;
  }

  TileMapServiceImageryProvider.prototype._metadataSuccess = function (xml) {
    var tileFormatRegex = /tileformat/i;
    var tileSetRegex = /tileset/i;
    var tileSetsRegex = /tilesets/i;
    var bboxRegex = /boundingbox/i;
    var format, bbox, tilesets;
    var tilesetsList = []; //list of TileSets
    var xmlResource = this._xmlResource;
    var metadataError = this._metadataError;
    var deferred = this._deferred;
    var requestMetadata = this._requestMetadata;

    // Allowing options properties (already copied to that) to override XML values

    // Iterate XML Document nodes for properties
    var nodeList = xml.childNodes[0].childNodes;
    for (var i = 0; i < nodeList.length; i++) {
      if (tileFormatRegex.test(nodeList.item(i).nodeName)) {
        format = nodeList.item(i);
      } else if (tileSetsRegex.test(nodeList.item(i).nodeName)) {
        tilesets = nodeList.item(i); // Node list of TileSets
        var tileSetNodes = nodeList.item(i).childNodes;
        // Iterate the nodes to find all TileSets
        for (var j = 0; j < tileSetNodes.length; j++) {
          if (tileSetRegex.test(tileSetNodes.item(j).nodeName)) {
            // Add them to tilesets list
            tilesetsList.push(tileSetNodes.item(j));
          }
        }
      } else if (bboxRegex.test(nodeList.item(i).nodeName)) {
        bbox = nodeList.item(i);
      }
    }

    var message;
    if (!defined(tilesets) || !defined(bbox)) {
      message =
        "Unable to find expected tilesets or bbox attributes in " +
        xmlResource.url +
        ".";
      metadataError = TileProviderError.handleError(
        metadataError,
        this,
        this.errorEvent,
        message,
        undefined,
        undefined,
        undefined,
        requestMetadata
      );
      if (!metadataError.retry) {
        deferred.reject(new RuntimeError(message));
      }
      this._metadataError = metadataError;
      return;
    }

    var options = this._options;
    var fileExtension = defaultValue(
      options.fileExtension,
      format.getAttribute("extension")
    );
    var tileWidth = defaultValue(
      options.tileWidth,
      parseInt(format.getAttribute("width"), 10)
    );
    var tileHeight = defaultValue(
      options.tileHeight,
      parseInt(format.getAttribute("height"), 10)
    );
    var minimumLevel = defaultValue(
      options.minimumLevel,
      parseInt(tilesetsList[0].getAttribute("order"), 10)
    );
    var maximumLevel = defaultValue(
      options.maximumLevel,
      parseInt(tilesetsList[tilesetsList.length - 1].getAttribute("order"), 10)
    );
    var tilingSchemeName = tilesets.getAttribute("profile");
    var tilingScheme = options.tilingScheme;

    if (!defined(tilingScheme)) {
      if (
        tilingSchemeName === "geodetic" ||
        tilingSchemeName === "global-geodetic"
      ) {
        tilingScheme = new GeographicTilingScheme({
          ellipsoid: options.ellipsoid,
        });
      } else if (
        tilingSchemeName === "mercator" ||
        tilingSchemeName === "global-mercator"
      ) {
        tilingScheme = new WebMercatorTilingScheme({
          ellipsoid: options.ellipsoid,
        });
      } else {
        message =
          xmlResource.url +
          "specifies an unsupported profile attribute, " +
          tilingSchemeName +
          ".";
        metadataError = TileProviderError.handleError(
          metadataError,
          this,
          this.errorEvent,
          message,
          undefined,
          undefined,
          undefined,
          requestMetadata
        );
        if (!metadataError.retry) {
          deferred.reject(new RuntimeError(message));
        }
        this._metadataError = metadataError;
        return;
      }
    }

    // rectangle handling
    var rectangle = Rectangle.clone(options.rectangle);

    if (!defined(rectangle)) {
      var sw;
      var ne;
      var swXY;
      var neXY;

      // In older versions of gdal x and y values were flipped, which is why we check for an option to flip
      // the values here as well. Unfortunately there is no way to autodetect whether flipping is needed.
      var flipXY = defaultValue(options.flipXY, false);
      if (flipXY) {
        swXY = new Cartesian2(
          parseFloat(bbox.getAttribute("miny")),
          parseFloat(bbox.getAttribute("minx"))
        );
        neXY = new Cartesian2(
          parseFloat(bbox.getAttribute("maxy")),
          parseFloat(bbox.getAttribute("maxx"))
        );
      } else {
        swXY = new Cartesian2(
          parseFloat(bbox.getAttribute("minx")),
          parseFloat(bbox.getAttribute("miny"))
        );
        neXY = new Cartesian2(
          parseFloat(bbox.getAttribute("maxx")),
          parseFloat(bbox.getAttribute("maxy"))
        );
      }

      // Determine based on the profile attribute if this tileset was generated by gdal2tiles.py, which
      // uses 'mercator' and 'geodetic' profiles, or by a tool compliant with the TMS standard, which is
      // 'global-mercator' and 'global-geodetic' profiles. In the gdal2Tiles case, X and Y are always in
      // geodetic degrees.
      var isGdal2tiles =
        tilingSchemeName === "geodetic" || tilingSchemeName === "mercator";
      if (
        tilingScheme.projection instanceof GeographicProjection ||
        isGdal2tiles
      ) {
        sw = Cartographic.fromDegrees(swXY.x, swXY.y);
        ne = Cartographic.fromDegrees(neXY.x, neXY.y);
      } else {
        var projection = tilingScheme.projection;
        sw = projection.unproject(swXY);
        ne = projection.unproject(neXY);
      }

      rectangle = new Rectangle(
        sw.longitude,
        sw.latitude,
        ne.longitude,
        ne.latitude
      );
    }

    // The rectangle must not be outside the bounds allowed by the tiling scheme.
    rectangle = confineRectangleToTilingScheme(rectangle, tilingScheme);
    // clamp our minimum detail level to something that isn't going to request a ridiculous number of tiles
    minimumLevel = calculateSafeMinimumDetailLevel(
      tilingScheme,
      rectangle,
      minimumLevel
    );

    var templateResource = this._tmsResource.getDerivedResource({
      url: "{z}/{x}/{reverseY}." + fileExtension,
    });

    deferred.resolve({
      url: templateResource,
      tilingScheme: tilingScheme,
      rectangle: rectangle,
      tileWidth: tileWidth,
      tileHeight: tileHeight,
      minimumLevel: minimumLevel,
      maximumLevel: maximumLevel,
      tileDiscardPolicy: options.tileDiscardPolicy,
      credit: options.credit,
    });
  };

  TileMapServiceImageryProvider.prototype._metadataFailure = function (error) {
    // Can't load XML, still allow options and defaults
    var options = this._options;
    var fileExtension = defaultValue(options.fileExtension, "png");
    var tileWidth = defaultValue(options.tileWidth, 256);
    var tileHeight = defaultValue(options.tileHeight, 256);
    var maximumLevel = options.maximumLevel;
    var tilingScheme = defined(options.tilingScheme)
      ? options.tilingScheme
      : new WebMercatorTilingScheme({ ellipsoid: options.ellipsoid });

    var rectangle = defaultValue(options.rectangle, tilingScheme.rectangle);
    // The rectangle must not be outside the bounds allowed by the tiling scheme.
    rectangle = confineRectangleToTilingScheme(rectangle, tilingScheme);

    // make sure we use a safe minimum detail level, so we don't request a ridiculous number of tiles
    var minimumLevel = calculateSafeMinimumDetailLevel(
      tilingScheme,
      rectangle,
      options.maximumLevel
    );

    var templateResource = this._tmsResource.getDerivedResource({
      url: "{z}/{x}/{reverseY}." + fileExtension,
    });

    this._deferred.resolve({
      url: templateResource,
      tilingScheme: tilingScheme,
      rectangle: rectangle,
      tileWidth: tileWidth,
      tileHeight: tileHeight,
      minimumLevel: minimumLevel,
      maximumLevel: maximumLevel,
      tileDiscardPolicy: options.tileDiscardPolicy,
      credit: options.credit,
    });
  };

  var trailingSlashRegex = /\/$/;
  var defaultCredit$1 = new Credit(
    '&copy; <a href="https://www.mapbox.com/about/maps/">Mapbox</a> &copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a> <strong><a href="https://www.mapbox.com/map-feedback/">Improve this map</a></strong>'
  );

  /**
   * @typedef {Object} MapboxImageryProvider.ConstructorOptions
   *
   * Initialization options for the MapboxImageryProvider constructor
   *
   * @property {String} [url='https://api.mapbox.com/v4/'] The Mapbox server url.
   * @property {String} mapId The Mapbox Map ID.
   * @property {String} accessToken The public access token for the imagery.
   * @property {String} [format='png'] The format of the image request.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.  Take care when specifying
   *                 this that the number of tiles at the minimum level is small, such as four or less.  A larger number is likely
   *                 to result in rendering problems.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle, in radians, covered by the image.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * Provides tiled imagery hosted by Mapbox.
   *
   * @alias MapboxImageryProvider
   * @constructor
   *
   * @param {MapboxImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @example
   * // Mapbox tile provider
   * var mapbox = new Cesium.MapboxImageryProvider({
   *     mapId: 'mapbox.streets',
   *     accessToken: 'thisIsMyAccessToken'
   * });
   *
   * @see {@link https://www.mapbox.com/developers/api/maps/#tiles}
   * @see {@link https://www.mapbox.com/developers/api/#access-tokens}
   */
  function MapboxImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var mapId = options.mapId;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(mapId)) {
      throw new DeveloperError("options.mapId is required.");
    }
    //>>includeEnd('debug');

    var accessToken = MapboxApi.getAccessToken(options.accessToken);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(accessToken)) {
      throw new DeveloperError("options.accessToken is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var resource = Resource.createIfNeeded(
      defaultValue(options.url, "https://{s}.tiles.mapbox.com/v4/")
    );

    this._mapId = mapId;
    this._accessToken = accessToken;

    var format = defaultValue(options.format, "png");
    if (!/\./.test(format)) {
      format = "." + format;
    }
    this._format = format;

    var templateUrl = resource.getUrlComponent();
    if (!trailingSlashRegex.test(templateUrl)) {
      templateUrl += "/";
    }
    templateUrl += mapId + "/{z}/{x}/{y}" + this._format;
    resource.url = templateUrl;

    resource.setQueryParameters({
      access_token: accessToken,
    });

    var credit;
    if (defined(options.credit)) {
      credit = options.credit;
      if (typeof credit === "string") {
        credit = new Credit(credit);
      }
    } else {
      credit = defaultCredit$1;
    }

    this._resource = resource;
    this._imageryProvider = new UrlTemplateImageryProvider({
      url: resource,
      credit: credit,
      ellipsoid: options.ellipsoid,
      minimumLevel: options.minimumLevel,
      maximumLevel: options.maximumLevel,
      rectangle: options.rectangle,
    });
  }

  Object.defineProperties(MapboxImageryProvider.prototype, {
    /**
     * Gets the URL of the Mapbox server.
     * @memberof MapboxImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._imageryProvider.url;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof MapboxImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._imageryProvider.ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof MapboxImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._imageryProvider.readyPromise;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by the instance.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._imageryProvider.rectangle;
      },
    },

    /**
     * Gets the width of each tile, in pixels.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        return this._imageryProvider.tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        return this._imageryProvider.tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        return this._imageryProvider.maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true. Generally,
     * a minimum level should only be used when the rectangle of the imagery is small
     * enough that the number of tiles at the minimum level is small.  An imagery
     * provider with more than a few tiles at the minimum level will lead to
     * rendering problems.
     * @memberof MapboxImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        return this._imageryProvider.minimumLevel;
      },
    },

    /**
     * Gets the tiling scheme used by the provider.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        return this._imageryProvider.tilingScheme;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        return this._imageryProvider.tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error..  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof MapboxImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._imageryProvider.errorEvent;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery. This function should
     * not be called before {@link MapboxImageryProvider#ready} returns true.
     * @memberof MapboxImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._imageryProvider.credit;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof MapboxImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._imageryProvider.proxy;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof MapboxImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return this._imageryProvider.hasAlphaChannel;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  MapboxImageryProvider.prototype.getTileCredits = function (x, y, level) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link MapboxImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  MapboxImageryProvider.prototype.requestImage = function (x, y, level, request) {
    return this._imageryProvider.requestImage(x, y, level, request);
  };

  /**
   * Asynchronously determines what features, if any, are located at a given longitude and latitude within
   * a tile.  This function should not be called before {@link MapboxImageryProvider#ready} returns true.
   * This function is optional, so it may not exist on all ImageryProviders.
   *
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   *
   * @exception {DeveloperError} <code>pickFeatures</code> must not be called before the imagery provider is ready.
   */
  MapboxImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return this._imageryProvider.pickFeatures(x, y, level, longitude, latitude);
  };

  // Exposed for tests
  MapboxImageryProvider._defaultCredit = defaultCredit$1;

  /**
   * @typedef {Object} SingleTileImageryProvider.ConstructorOptions
   *
   * Initialization options for the SingleTileImageryProvider constructor
   *
   * @property {Resource|String} url The url for the tile.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle, in radians, covered by the image.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   */

  /**
   * Provides a single, top-level imagery tile.  The single image is assumed to use a
   * {@link GeographicTilingScheme}.
   *
   * @alias SingleTileImageryProvider
   * @constructor
   *
   * @param {SingleTileImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   */
  function SingleTileImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var resource = Resource.createIfNeeded(options.url);

    var rectangle = defaultValue(options.rectangle, Rectangle.MAX_VALUE);
    var tilingScheme = new GeographicTilingScheme({
      rectangle: rectangle,
      numberOfLevelZeroTilesX: 1,
      numberOfLevelZeroTilesY: 1,
      ellipsoid: options.ellipsoid,
    });
    this._tilingScheme = tilingScheme;
    this._resource = resource;
    this._image = undefined;
    this._texture = undefined;
    this._tileWidth = 0;
    this._tileHeight = 0;

    this._errorEvent = new Event();

    this._ready = false;
    this._readyPromise = when.defer();

    var credit = options.credit;
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }
    this._credit = credit;

    var that = this;
    var error;

    function success(image) {
      that._image = image;
      that._tileWidth = image.width;
      that._tileHeight = image.height;
      that._ready = true;
      that._readyPromise.resolve(true);
      TileProviderError.handleSuccess(that._errorEvent);
    }

    function failure(e) {
      var message = "Failed to load image " + resource.url + ".";
      error = TileProviderError.handleError(
        error,
        that,
        that._errorEvent,
        message,
        0,
        0,
        0,
        doRequest,
        e
      );
      that._readyPromise.reject(new RuntimeError(message));
    }

    function doRequest() {
      ImageryProvider.loadImage(null, resource).then(success).otherwise(failure);
    }

    doRequest();
  }

  Object.defineProperties(SingleTileImageryProvider.prototype, {
    /**
     * Gets the URL of the single, top-level imagery tile.
     * @memberof SingleTileImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource.url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return 0;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return 0;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._tilingScheme.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');

        return undefined;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link SingleTileImageryProvider#ready} returns true.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof SingleTileImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return true;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  SingleTileImageryProvider.prototype.getTileCredits = function (x, y, level) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link SingleTileImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  SingleTileImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    return this._image;
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  SingleTileImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  /**
   * Provides functionality for ImageryProviders that have time dynamic imagery
   *
   * @alias TimeDynamicImagery
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Clock} options.clock A Clock instance that is used when determining the value for the time dimension. Required when <code>options.times</code> is specified.
   * @param {TimeIntervalCollection} options.times TimeIntervalCollection with its <code>data</code> property being an object containing time dynamic dimension and their values.
   * @param {Function} options.requestImageFunction A function that will request imagery tiles.
   * @param {Function} options.reloadFunction A function that will be called when all imagery tiles need to be reloaded.
   */
  function TimeDynamicImagery(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options.clock", options.clock);
    Check.typeOf.object("options.times", options.times);
    Check.typeOf.func(
      "options.requestImageFunction",
      options.requestImageFunction
    );
    Check.typeOf.func("options.reloadFunction", options.reloadFunction);
    //>>includeEnd('debug');

    this._tileCache = {};
    this._tilesRequestedForInterval = [];

    var clock = (this._clock = options.clock);
    this._times = options.times;
    this._requestImageFunction = options.requestImageFunction;
    this._reloadFunction = options.reloadFunction;
    this._currentIntervalIndex = -1;

    clock.onTick.addEventListener(this._clockOnTick, this);
    this._clockOnTick(clock);
  }

  Object.defineProperties(TimeDynamicImagery.prototype, {
    /**
     * Gets or sets a clock that is used to get keep the time used for time dynamic parameters.
     * @memberof TimeDynamicImagery.prototype
     * @type {Clock}
     */
    clock: {
      get: function () {
        return this._clock;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._clock !== value) {
          this._clock = value;
          this._clockOnTick(value);
          this._reloadFunction();
        }
      },
    },
    /**
     * Gets or sets a time interval collection.
     * @memberof TimeDynamicImagery.prototype
     * @type {TimeIntervalCollection}
     */
    times: {
      get: function () {
        return this._times;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
          throw new DeveloperError("value is required.");
        }
        //>>includeEnd('debug');

        if (this._times !== value) {
          this._times = value;
          this._clockOnTick(this._clock);
          this._reloadFunction();
        }
      },
    },
    /**
     * Gets the current interval.
     * @memberof TimeDynamicImagery.prototype
     * @type {TimeInterval}
     */
    currentInterval: {
      get: function () {
        return this._times.get(this._currentIntervalIndex);
      },
    },
  });

  /**
   * Gets the tile from the cache if its available.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   *
   * @returns {Promise.<HTMLImageElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if the tile is not in the cache.
   */
  TimeDynamicImagery.prototype.getFromCache = function (x, y, level, request) {
    var key = getKey$1(x, y, level);
    var result;
    var cache = this._tileCache[this._currentIntervalIndex];
    if (defined(cache) && defined(cache[key])) {
      var item = cache[key];
      result = item.promise.otherwise(function (e) {
        // Set the correct state in case it was cancelled
        request.state = item.request.state;
        throw e;
      });
      delete cache[key];
    }

    return result;
  };

  /**
   * Checks if the next interval is approaching and will start preload the tile if necessary. Otherwise it will
   * just add the tile to a list to preload when we approach the next interval.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   */
  TimeDynamicImagery.prototype.checkApproachingInterval = function (
    x,
    y,
    level,
    request
  ) {
    var key = getKey$1(x, y, level);
    var tilesRequestedForInterval = this._tilesRequestedForInterval;

    // If we are approaching an interval, preload this tile in the next interval
    var approachingInterval = getApproachingInterval(this);
    var tile = {
      key: key,
      // Determines priority based on camera distance to the tile.
      // Since the imagery regardless of time will be attached to the same tile we can just steal it.
      priorityFunction: request.priorityFunction,
    };
    if (
      !defined(approachingInterval) ||
      !addToCache(this, tile, approachingInterval)
    ) {
      // Add to recent request list if we aren't approaching and interval or the request was throttled
      tilesRequestedForInterval.push(tile);
    }

    // Don't let the tile list get out of hand
    if (tilesRequestedForInterval.length >= 512) {
      tilesRequestedForInterval.splice(0, 256);
    }
  };

  TimeDynamicImagery.prototype._clockOnTick = function (clock) {
    var time = clock.currentTime;
    var times = this._times;
    var index = times.indexOf(time);
    var currentIntervalIndex = this._currentIntervalIndex;

    if (index !== currentIntervalIndex) {
      // Cancel all outstanding requests and clear out caches not from current time interval
      var currentCache = this._tileCache[currentIntervalIndex];
      for (var t in currentCache) {
        if (currentCache.hasOwnProperty(t)) {
          currentCache[t].request.cancel();
        }
      }
      delete this._tileCache[currentIntervalIndex];
      this._tilesRequestedForInterval = [];

      this._currentIntervalIndex = index;
      this._reloadFunction();

      return;
    }

    var approachingInterval = getApproachingInterval(this);
    if (defined(approachingInterval)) {
      // Start loading recent tiles from end of this._tilesRequestedForInterval
      //  We keep preloading until we hit a throttling limit.
      var tilesRequested = this._tilesRequestedForInterval;
      var success = true;
      while (success) {
        if (tilesRequested.length === 0) {
          break;
        }

        var tile = tilesRequested.pop();
        success = addToCache(this, tile, approachingInterval);
        if (!success) {
          tilesRequested.push(tile);
        }
      }
    }
  };

  function getKey$1(x, y, level) {
    return x + "-" + y + "-" + level;
  }

  function getKeyElements(key) {
    var s = key.split("-");
    if (s.length !== 3) {
      return undefined;
    }

    return {
      x: Number(s[0]),
      y: Number(s[1]),
      level: Number(s[2]),
    };
  }

  function getApproachingInterval(that) {
    var times = that._times;
    if (!defined(times)) {
      return undefined;
    }
    var clock = that._clock;
    var time = clock.currentTime;
    var isAnimating = clock.canAnimate && clock.shouldAnimate;
    var multiplier = clock.multiplier;

    if (!isAnimating && multiplier !== 0) {
      return undefined;
    }

    var seconds;
    var index = times.indexOf(time);
    if (index < 0) {
      return undefined;
    }

    var interval = times.get(index);
    if (multiplier > 0) {
      // animating forward
      seconds = JulianDate.secondsDifference(interval.stop, time);
      ++index;
    } else {
      //backwards
      seconds = JulianDate.secondsDifference(interval.start, time); // Will be negative
      --index;
    }
    seconds /= multiplier; // Will always be positive

    // Less than 5 wall time seconds
    return index >= 0 && seconds <= 5.0 ? times.get(index) : undefined;
  }

  function addToCache(that, tile, interval) {
    var index = that._times.indexOf(interval.start);
    var tileCache = that._tileCache;
    var intervalTileCache = tileCache[index];
    if (!defined(intervalTileCache)) {
      intervalTileCache = tileCache[index] = {};
    }

    var key = tile.key;
    if (defined(intervalTileCache[key])) {
      return true; // Already in the cache
    }

    var keyElements = getKeyElements(key);
    var request = new Request({
      throttle: true,
      throttleByServer: true,
      type: RequestType$1.IMAGERY,
      priorityFunction: tile.priorityFunction,
    });
    var promise = that._requestImageFunction(
      keyElements.x,
      keyElements.y,
      keyElements.level,
      request,
      interval
    );
    if (!defined(promise)) {
      return false;
    }

    intervalTileCache[key] = {
      promise: promise,
      request: request,
    };

    return true;
  }

  /**
   * @typedef {Object} WebMapServiceImageryProvider.ConstructorOptions
   *
   * Initialization options for the WebMapServiceImageryProvider constructor
   *
   * @property {Resource|String} url The URL of the WMS service. The URL supports the same keywords as the {@link UrlTemplateImageryProvider}.
   * @property {String} layers The layers to include, separated by commas.
   * @property {Object} [parameters=WebMapServiceImageryProvider.DefaultParameters] Additional parameters to pass to the WMS server in the GetMap URL.
   * @property {Object} [getFeatureInfoParameters=WebMapServiceImageryProvider.GetFeatureInfoDefaultParameters] Additional parameters to pass to the WMS server in the GetFeatureInfo URL.
   * @property {Boolean} [enablePickFeatures=true] If true, {@link WebMapServiceImageryProvider#pickFeatures} will invoke
   *        the GetFeatureInfo operation on the WMS server and return the features included in the response.  If false,
   *        {@link WebMapServiceImageryProvider#pickFeatures} will immediately return undefined (indicating no pickable features)
   *        without communicating with the server.  Set this property to false if you know your WMS server does not support
   *        GetFeatureInfo or if you don't want this provider's features to be pickable. Note that this can be dynamically
   *        overridden by modifying the WebMapServiceImageryProvider#enablePickFeatures property.
   * @property {GetFeatureInfoFormat[]} [getFeatureInfoFormats=WebMapServiceImageryProvider.DefaultGetFeatureInfoFormats] The formats
   *        in which to try WMS GetFeatureInfo requests.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle of the layer.
   * @property {TilingScheme} [tilingScheme=new GeographicTilingScheme()] The tiling scheme to use to divide the world into tiles.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   *        this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   *        parameter is specified, the WGS84 ellipsoid is used.
   * @property {Number} [tileWidth=256] The width of each tile in pixels.
   * @property {Number} [tileHeight=256] The height of each tile in pixels.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.  Take care when
   *        specifying this that the number of tiles at the minimum level is small, such as four or less.  A larger number is
   *        likely to result in rendering problems.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   *        If not specified, there is no limit.
   * @property {String} [crs] CRS specification, for use with WMS specification >= 1.3.0.
   * @property {String} [srs] SRS specification, for use with WMS specification 1.1.0 or 1.1.1
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   * @property {String|String[]} [subdomains='abc'] The subdomains to use for the <code>{s}</code> placeholder in the URL template.
   *                          If this parameter is a single string, each character in the string is a subdomain.  If it is
   *                          an array, each element in the array is a subdomain.
   * @property {Clock} [clock] A Clock instance that is used when determining the value for the time dimension. Required when `times` is specified.
   * @property {TimeIntervalCollection} [times] TimeIntervalCollection with its data property being an object containing time dynamic dimension and their values.
   */

  /**
   * Provides tiled imagery hosted by a Web Map Service (WMS) server.
   *
   * @alias WebMapServiceImageryProvider
   * @constructor
   *
   * @param {WebMapServiceImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   * @see {@link http://resources.esri.com/help/9.3/arcgisserver/apis/rest/|ArcGIS Server REST API}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   *
   * @example
   * var provider = new Cesium.WebMapServiceImageryProvider({
   *     url : 'https://sampleserver1.arcgisonline.com/ArcGIS/services/Specialty/ESRI_StatesCitiesRivers_USA/MapServer/WMSServer',
   *     layers : '0',
   *     proxy: new Cesium.DefaultProxy('/proxy/')
   * });
   *
   * viewer.imageryLayers.addImageryProvider(provider);
   */
  function WebMapServiceImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    if (!defined(options.layers)) {
      throw new DeveloperError("options.layers is required.");
    }
    //>>includeEnd('debug');

    if (defined(options.times) && !defined(options.clock)) {
      throw new DeveloperError(
        "options.times was specified, so options.clock is required."
      );
    }

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var resource = Resource.createIfNeeded(options.url);

    var pickFeatureResource = resource.clone();

    resource.setQueryParameters(
      WebMapServiceImageryProvider.DefaultParameters,
      true
    );
    pickFeatureResource.setQueryParameters(
      WebMapServiceImageryProvider.GetFeatureInfoDefaultParameters,
      true
    );

    if (defined(options.parameters)) {
      resource.setQueryParameters(objectToLowercase(options.parameters));
    }

    if (defined(options.getFeatureInfoParameters)) {
      pickFeatureResource.setQueryParameters(
        objectToLowercase(options.getFeatureInfoParameters)
      );
    }

    var that = this;
    this._reload = undefined;
    if (defined(options.times)) {
      this._timeDynamicImagery = new TimeDynamicImagery({
        clock: options.clock,
        times: options.times,
        requestImageFunction: function (x, y, level, request, interval) {
          return requestImage(that, x, y, level, request, interval);
        },
        reloadFunction: function () {
          if (defined(that._reload)) {
            that._reload();
          }
        },
      });
    }

    var parameters = {};
    parameters.layers = options.layers;
    parameters.bbox =
      "{westProjected},{southProjected},{eastProjected},{northProjected}";
    parameters.width = "{width}";
    parameters.height = "{height}";

    // Use SRS or CRS based on the WMS version.
    if (parseFloat(resource.queryParameters.version) >= 1.3) {
      // Use CRS with 1.3.0 and going forward.
      // For GeographicTilingScheme, use CRS:84 vice EPSG:4326 to specify lon, lat (x, y) ordering for
      // bbox requests.
      parameters.crs = defaultValue(
        options.crs,
        options.tilingScheme &&
          options.tilingScheme.projection instanceof WebMercatorProjection
          ? "EPSG:3857"
          : "CRS:84"
      );
    } else {
      // SRS for WMS 1.1.0 or 1.1.1.
      parameters.srs = defaultValue(
        options.srs,
        options.tilingScheme &&
          options.tilingScheme.projection instanceof WebMercatorProjection
          ? "EPSG:3857"
          : "EPSG:4326"
      );
    }

    resource.setQueryParameters(parameters, true);
    pickFeatureResource.setQueryParameters(parameters, true);

    var pickFeatureParams = {
      query_layers: options.layers,
      x: "{i}",
      y: "{j}",
      info_format: "{format}",
    };
    pickFeatureResource.setQueryParameters(pickFeatureParams, true);

    this._resource = resource;
    this._pickFeaturesResource = pickFeatureResource;
    this._layers = options.layers;

    // Let UrlTemplateImageryProvider do the actual URL building.
    this._tileProvider = new UrlTemplateImageryProvider({
      url: resource,
      pickFeaturesUrl: pickFeatureResource,
      tilingScheme: defaultValue(
        options.tilingScheme,
        new GeographicTilingScheme({ ellipsoid: options.ellipsoid })
      ),
      rectangle: options.rectangle,
      tileWidth: options.tileWidth,
      tileHeight: options.tileHeight,
      minimumLevel: options.minimumLevel,
      maximumLevel: options.maximumLevel,
      subdomains: options.subdomains,
      tileDiscardPolicy: options.tileDiscardPolicy,
      credit: options.credit,
      getFeatureInfoFormats: defaultValue(
        options.getFeatureInfoFormats,
        WebMapServiceImageryProvider.DefaultGetFeatureInfoFormats
      ),
      enablePickFeatures: options.enablePickFeatures,
    });
  }

  function requestImage(imageryProvider, col, row, level, request, interval) {
    var dynamicIntervalData = defined(interval) ? interval.data : undefined;
    var tileProvider = imageryProvider._tileProvider;

    if (defined(dynamicIntervalData)) {
      // We set the query parameters within the tile provider, because it is managing the query.
      tileProvider._resource.setQueryParameters(dynamicIntervalData);
    }
    return tileProvider.requestImage(col, row, level, request);
  }

  function pickFeatures(
    imageryProvider,
    x,
    y,
    level,
    longitude,
    latitude,
    interval
  ) {
    var dynamicIntervalData = defined(interval) ? interval.data : undefined;
    var tileProvider = imageryProvider._tileProvider;

    if (defined(dynamicIntervalData)) {
      // We set the query parameters within the tile provider, because it is managing the query.
      tileProvider._pickFeaturesResource.setQueryParameters(dynamicIntervalData);
    }
    return tileProvider.pickFeatures(x, y, level, longitude, latitude);
  }

  Object.defineProperties(WebMapServiceImageryProvider.prototype, {
    /**
     * Gets the URL of the WMS server.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource._url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the names of the WMS layers, separated by commas.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    layers: {
      get: function () {
        return this._layers;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        return this._tileProvider.tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        return this._tileProvider.tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        return this._tileProvider.maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        return this._tileProvider.minimumLevel;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        return this._tileProvider.tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._tileProvider.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        return this._tileProvider.tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._tileProvider.errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._tileProvider.ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._tileProvider.readyPromise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link WebMapServiceImageryProvider#ready} returns true.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._tileProvider.credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return this._tileProvider.hasAlphaChannel;
      },
    },

    /**
     * Gets or sets a value indicating whether feature picking is enabled.  If true, {@link WebMapServiceImageryProvider#pickFeatures} will
     * invoke the <code>GetFeatureInfo</code> service on the WMS server and attempt to interpret the features included in the response.  If false,
     * {@link WebMapServiceImageryProvider#pickFeatures} will immediately return undefined (indicating no pickable
     * features) without communicating with the server.  Set this property to false if you know your data
     * source does not support picking features or if you don't want this provider's features to be pickable.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Boolean}
     * @default true
     */
    enablePickFeatures: {
      get: function () {
        return this._tileProvider.enablePickFeatures;
      },
      set: function (enablePickFeatures) {
        this._tileProvider.enablePickFeatures = enablePickFeatures;
      },
    },

    /**
     * Gets or sets a clock that is used to get keep the time used for time dynamic parameters.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {Clock}
     */
    clock: {
      get: function () {
        return this._timeDynamicImagery.clock;
      },
      set: function (value) {
        this._timeDynamicImagery.clock = value;
      },
    },
    /**
     * Gets or sets a time interval collection that is used to get time dynamic parameters. The data of each
     * TimeInterval is an object containing the keys and values of the properties that are used during
     * tile requests.
     * @memberof WebMapServiceImageryProvider.prototype
     * @type {TimeIntervalCollection}
     */
    times: {
      get: function () {
        return this._timeDynamicImagery.times;
      },
      set: function (value) {
        this._timeDynamicImagery.times = value;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  WebMapServiceImageryProvider.prototype.getTileCredits = function (x, y, level) {
    return this._tileProvider.getTileCredits(x, y, level);
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  WebMapServiceImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    var result;
    var timeDynamicImagery = this._timeDynamicImagery;
    var currentInterval;

    // Try and load from cache
    if (defined(timeDynamicImagery)) {
      currentInterval = timeDynamicImagery.currentInterval;
      result = timeDynamicImagery.getFromCache(x, y, level, request);
    }

    // Couldn't load from cache
    if (!defined(result)) {
      result = requestImage(this, x, y, level, request, currentInterval);
    }

    // If we are approaching an interval, preload this tile in the next interval
    if (defined(result) && defined(timeDynamicImagery)) {
      timeDynamicImagery.checkApproachingInterval(x, y, level, request);
    }

    return result;
  };

  /**
   * Asynchronously determines what features, if any, are located at a given longitude and latitude within
   * a tile.  This function should not be called before {@link ImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *
   * @exception {DeveloperError} <code>pickFeatures</code> must not be called before the imagery provider is ready.
   */
  WebMapServiceImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    var timeDynamicImagery = this._timeDynamicImagery;
    var currentInterval = defined(timeDynamicImagery)
      ? timeDynamicImagery.currentInterval
      : undefined;

    return pickFeatures(this, x, y, level, longitude, latitude, currentInterval);
  };

  /**
   * The default parameters to include in the WMS URL to obtain images.  The values are as follows:
   *    service=WMS
   *    version=1.1.1
   *    request=GetMap
   *    styles=
   *    format=image/jpeg
   *
   * @constant
   * @type {Object}
   */
  WebMapServiceImageryProvider.DefaultParameters = Object.freeze({
    service: "WMS",
    version: "1.1.1",
    request: "GetMap",
    styles: "",
    format: "image/jpeg",
  });

  /**
   * The default parameters to include in the WMS URL to get feature information.  The values are as follows:
   *     service=WMS
   *     version=1.1.1
   *     request=GetFeatureInfo
   *
   * @constant
   * @type {Object}
   */
  WebMapServiceImageryProvider.GetFeatureInfoDefaultParameters = Object.freeze({
    service: "WMS",
    version: "1.1.1",
    request: "GetFeatureInfo",
  });

  WebMapServiceImageryProvider.DefaultGetFeatureInfoFormats = Object.freeze([
    Object.freeze(new GetFeatureInfoFormat("json", "application/json")),
    Object.freeze(new GetFeatureInfoFormat("xml", "text/xml")),
    Object.freeze(new GetFeatureInfoFormat("text", "text/html")),
  ]);

  function objectToLowercase(obj) {
    var result = {};
    for (var key in obj) {
      if (obj.hasOwnProperty(key)) {
        result[key.toLowerCase()] = obj[key];
      }
    }
    return result;
  }

  var defaultParameters = Object.freeze({
    service: "WMTS",
    version: "1.0.0",
    request: "GetTile",
  });

  /**
   * @typedef {Object} WebMapTileServiceImageryProvider.ConstructorOptions
   *
   * Initialization options for the WebMapTileServiceImageryProvider constructor
   *
   * @property {Resource|String} url The base URL for the WMTS GetTile operation (for KVP-encoded requests) or the tile-URL template (for RESTful requests). The tile-URL template should contain the following variables: &#123;style&#125;, &#123;TileMatrixSet&#125;, &#123;TileMatrix&#125;, &#123;TileRow&#125;, &#123;TileCol&#125;. The first two are optional if actual values are hardcoded or not required by the server. The &#123;s&#125; keyword may be used to specify subdomains.
   * @property {String} [format='image/jpeg'] The MIME type for images to retrieve from the server.
   * @property {String} layer The layer name for WMTS requests.
   * @property {String} style The style name for WMTS requests.
   * @property {String} tileMatrixSetID The identifier of the TileMatrixSet to use for WMTS requests.
   * @property {Array} [tileMatrixLabels] A list of identifiers in the TileMatrix to use for WMTS requests, one per TileMatrix level.
   * @property {Clock} [clock] A Clock instance that is used when determining the value for the time dimension. Required when `times` is specified.
   * @property {TimeIntervalCollection} [times] TimeIntervalCollection with its <code>data</code> property being an object containing time dynamic dimension and their values.
   * @property {Object} [dimensions] A object containing static dimensions and their values.
   * @property {Number} [tileWidth=256] The tile width in pixels.
   * @property {Number} [tileHeight=256] The tile height in pixels.
   * @property {TilingScheme} [tilingScheme] The tiling scheme corresponding to the organization of the tiles in the TileMatrixSet.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle covered by the layer.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   * @property {String|String[]} [subdomains='abc'] The subdomains to use for the <code>{s}</code> placeholder in the URL template.
   *                          If this parameter is a single string, each character in the string is a subdomain.  If it is
   *                          an array, each element in the array is a subdomain.
   */

  /**
   * Provides tiled imagery served by {@link http://www.opengeospatial.org/standards/wmts|WMTS 1.0.0} compliant servers.
   * This provider supports HTTP KVP-encoded and RESTful GetTile requests, but does not yet support the SOAP encoding.
   *
   * @alias WebMapTileServiceImageryProvider
   * @constructor
   *
   * @param {WebMapTileServiceImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Web%20Map%20Tile%20Service%20with%20Time.html|Cesium Sandcastle Web Map Tile Service with Time Demo}
   *
   * @example
   * // Example 1. USGS shaded relief tiles (KVP)
   * var shadedRelief1 = new Cesium.WebMapTileServiceImageryProvider({
   *     url : 'http://basemap.nationalmap.gov/arcgis/rest/services/USGSShadedReliefOnly/MapServer/WMTS',
   *     layer : 'USGSShadedReliefOnly',
   *     style : 'default',
   *     format : 'image/jpeg',
   *     tileMatrixSetID : 'default028mm',
   *     // tileMatrixLabels : ['default028mm:0', 'default028mm:1', 'default028mm:2' ...],
   *     maximumLevel: 19,
   *     credit : new Cesium.Credit('U. S. Geological Survey')
   * });
   * viewer.imageryLayers.addImageryProvider(shadedRelief1);
   *
   * @example
   * // Example 2. USGS shaded relief tiles (RESTful)
   * var shadedRelief2 = new Cesium.WebMapTileServiceImageryProvider({
   *     url : 'http://basemap.nationalmap.gov/arcgis/rest/services/USGSShadedReliefOnly/MapServer/WMTS/tile/1.0.0/USGSShadedReliefOnly/{Style}/{TileMatrixSet}/{TileMatrix}/{TileRow}/{TileCol}.jpg',
   *     layer : 'USGSShadedReliefOnly',
   *     style : 'default',
   *     format : 'image/jpeg',
   *     tileMatrixSetID : 'default028mm',
   *     maximumLevel: 19,
   *     credit : new Cesium.Credit('U. S. Geological Survey')
   * });
   * viewer.imageryLayers.addImageryProvider(shadedRelief2);
   *
   * @example
   * // Example 3. NASA time dynamic weather data (RESTful)
   * var times = Cesium.TimeIntervalCollection.fromIso8601({
   *     iso8601: '2015-07-30/2017-06-16/P1D',
   *     dataCallback: function dataCallback(interval, index) {
   *         return {
   *             Time: Cesium.JulianDate.toIso8601(interval.start)
   *         };
   *     }
   * });
   * var weather = new Cesium.WebMapTileServiceImageryProvider({
   *     url : 'https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/AMSR2_Snow_Water_Equivalent/default/{Time}/{TileMatrixSet}/{TileMatrix}/{TileRow}/{TileCol}.png',
   *     layer : 'AMSR2_Snow_Water_Equivalent',
   *     style : 'default',
   *     tileMatrixSetID : '2km',
   *     maximumLevel : 5,
   *     format : 'image/png',
   *     clock: clock,
   *     times: times,
   *     credit : new Cesium.Credit('NASA Global Imagery Browse Services for EOSDIS')
   * });
   * viewer.imageryLayers.addImageryProvider(weather);
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see OpenStreetMapImageryProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see UrlTemplateImageryProvider
   */
  function WebMapTileServiceImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.url)) {
      throw new DeveloperError("options.url is required.");
    }
    if (!defined(options.layer)) {
      throw new DeveloperError("options.layer is required.");
    }
    if (!defined(options.style)) {
      throw new DeveloperError("options.style is required.");
    }
    if (!defined(options.tileMatrixSetID)) {
      throw new DeveloperError("options.tileMatrixSetID is required.");
    }
    if (defined(options.times) && !defined(options.clock)) {
      throw new DeveloperError(
        "options.times was specified, so options.clock is required."
      );
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var resource = Resource.createIfNeeded(options.url);

    var style = options.style;
    var tileMatrixSetID = options.tileMatrixSetID;
    var url = resource.url;
    if (url.indexOf("{") >= 0) {
      var templateValues = {
        style: style,
        Style: style,
        TileMatrixSet: tileMatrixSetID,
      };

      resource.setTemplateValues(templateValues);
      this._useKvp = false;
    } else {
      resource.setQueryParameters(defaultParameters);
      this._useKvp = true;
    }

    this._resource = resource;
    this._layer = options.layer;
    this._style = style;
    this._tileMatrixSetID = tileMatrixSetID;
    this._tileMatrixLabels = options.tileMatrixLabels;
    this._format = defaultValue(options.format, "image/jpeg");
    this._tileDiscardPolicy = options.tileDiscardPolicy;

    this._tilingScheme = defined(options.tilingScheme)
      ? options.tilingScheme
      : new WebMercatorTilingScheme({ ellipsoid: options.ellipsoid });
    this._tileWidth = defaultValue(options.tileWidth, 256);
    this._tileHeight = defaultValue(options.tileHeight, 256);

    this._minimumLevel = defaultValue(options.minimumLevel, 0);
    this._maximumLevel = options.maximumLevel;

    this._rectangle = defaultValue(
      options.rectangle,
      this._tilingScheme.rectangle
    );
    this._dimensions = options.dimensions;

    var that = this;
    this._reload = undefined;
    if (defined(options.times)) {
      this._timeDynamicImagery = new TimeDynamicImagery({
        clock: options.clock,
        times: options.times,
        requestImageFunction: function (x, y, level, request, interval) {
          return requestImage$1(that, x, y, level, request, interval);
        },
        reloadFunction: function () {
          if (defined(that._reload)) {
            that._reload();
          }
        },
      });
    }

    this._readyPromise = when.resolve(true);

    // Check the number of tiles at the minimum level.  If it's more than four,
    // throw an exception, because starting at the higher minimum
    // level will cause too many tiles to be downloaded and rendered.
    var swTile = this._tilingScheme.positionToTileXY(
      Rectangle.southwest(this._rectangle),
      this._minimumLevel
    );
    var neTile = this._tilingScheme.positionToTileXY(
      Rectangle.northeast(this._rectangle),
      this._minimumLevel
    );
    var tileCount =
      (Math.abs(neTile.x - swTile.x) + 1) * (Math.abs(neTile.y - swTile.y) + 1);
    //>>includeStart('debug', pragmas.debug);
    if (tileCount > 4) {
      throw new DeveloperError(
        "The imagery provider's rectangle and minimumLevel indicate that there are " +
          tileCount +
          " tiles at the minimum level. Imagery providers with more than four tiles at the minimum level are not supported."
      );
    }
    //>>includeEnd('debug');

    this._errorEvent = new Event();

    var credit = options.credit;
    this._credit = typeof credit === "string" ? new Credit(credit) : credit;

    this._subdomains = options.subdomains;
    if (Array.isArray(this._subdomains)) {
      this._subdomains = this._subdomains.slice();
    } else if (defined(this._subdomains) && this._subdomains.length > 0) {
      this._subdomains = this._subdomains.split("");
    } else {
      this._subdomains = ["a", "b", "c"];
    }
  }

  function requestImage$1(imageryProvider, col, row, level, request, interval) {
    var labels = imageryProvider._tileMatrixLabels;
    var tileMatrix = defined(labels) ? labels[level] : level.toString();
    var subdomains = imageryProvider._subdomains;
    var staticDimensions = imageryProvider._dimensions;
    var dynamicIntervalData = defined(interval) ? interval.data : undefined;

    var resource;
    if (!imageryProvider._useKvp) {
      var templateValues = {
        TileMatrix: tileMatrix,
        TileRow: row.toString(),
        TileCol: col.toString(),
        s: subdomains[(col + row + level) % subdomains.length],
      };

      resource = imageryProvider._resource.getDerivedResource({
        request: request,
      });
      resource.setTemplateValues(templateValues);

      if (defined(staticDimensions)) {
        resource.setTemplateValues(staticDimensions);
      }

      if (defined(dynamicIntervalData)) {
        resource.setTemplateValues(dynamicIntervalData);
      }
    } else {
      // build KVP request
      var query = {};
      query.tilematrix = tileMatrix;
      query.layer = imageryProvider._layer;
      query.style = imageryProvider._style;
      query.tilerow = row;
      query.tilecol = col;
      query.tilematrixset = imageryProvider._tileMatrixSetID;
      query.format = imageryProvider._format;

      if (defined(staticDimensions)) {
        query = combine(query, staticDimensions);
      }

      if (defined(dynamicIntervalData)) {
        query = combine(query, dynamicIntervalData);
      }
      resource = imageryProvider._resource.getDerivedResource({
        queryParameters: query,
        request: request,
      });
    }

    return ImageryProvider.loadImage(imageryProvider, resource);
  }

  Object.defineProperties(WebMapTileServiceImageryProvider.prototype, {
    /**
     * Gets the URL of the service hosting the imagery.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._resource.url;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._resource.proxy;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        return this._maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        return this._minimumLevel;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        return this._tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets the mime type of images returned by this imagery provider.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    format: {
      get: function () {
        return this._format;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      value: true,
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return true;
      },
    },
    /**
     * Gets or sets a clock that is used to get keep the time used for time dynamic parameters.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Clock}
     */
    clock: {
      get: function () {
        return this._timeDynamicImagery.clock;
      },
      set: function (value) {
        this._timeDynamicImagery.clock = value;
      },
    },
    /**
     * Gets or sets a time interval collection that is used to get time dynamic parameters. The data of each
     * TimeInterval is an object containing the keys and values of the properties that are used during
     * tile requests.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {TimeIntervalCollection}
     */
    times: {
      get: function () {
        return this._timeDynamicImagery.times;
      },
      set: function (value) {
        this._timeDynamicImagery.times = value;
      },
    },
    /**
     * Gets or sets an object that contains static dimensions and their values.
     * @memberof WebMapTileServiceImageryProvider.prototype
     * @type {Object}
     */
    dimensions: {
      get: function () {
        return this._dimensions;
      },
      set: function (value) {
        if (this._dimensions !== value) {
          this._dimensions = value;
          if (defined(this._reload)) {
            this._reload();
          }
        }
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  WebMapTileServiceImageryProvider.prototype.getTileCredits = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  WebMapTileServiceImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    var result;
    var timeDynamicImagery = this._timeDynamicImagery;
    var currentInterval;

    // Try and load from cache
    if (defined(timeDynamicImagery)) {
      currentInterval = timeDynamicImagery.currentInterval;
      result = timeDynamicImagery.getFromCache(x, y, level, request);
    }

    // Couldn't load from cache
    if (!defined(result)) {
      result = requestImage$1(this, x, y, level, request, currentInterval);
    }

    // If we are approaching an interval, preload this tile in the next interval
    if (defined(result) && defined(timeDynamicImagery)) {
      timeDynamicImagery.checkApproachingInterval(x, y, level, request);
    }

    return result;
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  WebMapTileServiceImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  function createFactory(Type) {
    return function (options) {
      return new Type(options);
    };
  }

  // These values are the list of supported external imagery
  // assets in the Cesium ion beta. They are subject to change.
  var ImageryProviderMapping = {
    ARCGIS_MAPSERVER: createFactory(ArcGisMapServerImageryProvider),
    BING: createFactory(BingMapsImageryProvider),
    GOOGLE_EARTH: createFactory(GoogleEarthEnterpriseMapsProvider),
    MAPBOX: createFactory(MapboxImageryProvider),
    SINGLE_TILE: createFactory(SingleTileImageryProvider),
    TMS: createFactory(TileMapServiceImageryProvider),
    URL_TEMPLATE: createFactory(UrlTemplateImageryProvider),
    WMS: createFactory(WebMapServiceImageryProvider),
    WMTS: createFactory(WebMapTileServiceImageryProvider),
  };

  /**
   * @typedef {Object} IonImageryProvider.ConstructorOptions
   *
   * Initialization options for the TileMapServiceImageryProvider constructor
   *
   * @property {Number} assetId An ion imagery asset ID
   * @property {String} [accessToken=Ion.defaultAccessToken] The access token to use.
   * @property {String|Resource} [server=Ion.defaultServer] The resource to the Cesium ion API server.
   */

  /**
   * Provides tiled imagery using the Cesium ion REST API.
   *
   * @alias IonImageryProvider
   * @constructor
   *
   * @param {IonImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @example
   * viewer.imageryLayers.addImageryProvider(new Cesium.IonImageryProvider({ assetId : 23489024 }));
   */
  function IonImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var assetId = options.assetId;
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number("options.assetId", assetId);
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    this._ready = false;
    this._tileCredits = undefined;
    this._errorEvent = new Event();

    var that = this;
    var endpointResource = IonResource._createEndpointResource(assetId, options);

    // A simple cache to avoid making repeated requests to ion for endpoints we've
    // already retrieved. This exists mainly to support Bing caching to reduce
    // world imagery sessions, but provides a small boost of performance in general
    // if constantly reloading assets
    var cacheKey =
      options.assetId.toString() + options.accessToken + options.server;
    var promise = IonImageryProvider._endpointCache[cacheKey];
    if (!defined(promise)) {
      promise = endpointResource.fetchJson();
      IonImageryProvider._endpointCache[cacheKey] = promise;
    }

    this._readyPromise = promise.then(function (endpoint) {
      if (endpoint.type !== "IMAGERY") {
        return when.reject(
          new RuntimeError(
            "Cesium ion asset " + assetId + " is not an imagery asset."
          )
        );
      }

      var imageryProvider;
      var externalType = endpoint.externalType;
      if (!defined(externalType)) {
        imageryProvider = new TileMapServiceImageryProvider({
          url: new IonResource(endpoint, endpointResource),
        });
      } else {
        var factory = ImageryProviderMapping[externalType];

        if (!defined(factory)) {
          return when.reject(
            new RuntimeError(
              "Unrecognized Cesium ion imagery type: " + externalType
            )
          );
        }
        imageryProvider = factory(endpoint.options);
      }

      that._tileCredits = IonResource.getCreditsFromEndpoint(
        endpoint,
        endpointResource
      );

      imageryProvider.errorEvent.addEventListener(function (tileProviderError) {
        //Propagate the errorEvent but set the provider to this instance instead
        //of the inner instance.
        tileProviderError.provider = that;
        that._errorEvent.raiseEvent(tileProviderError);
      });

      that._imageryProvider = imageryProvider;
      return imageryProvider.readyPromise.then(function () {
        that._ready = true;
        return true;
      });
    });
  }

  Object.defineProperties(IonImageryProvider.prototype, {
    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof IonImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof IonImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by the instance.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.rectangle;
      },
    },

    /**
     * Gets the width of each tile, in pixels.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileWidth must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileHeight must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "maximumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true. Generally,
     * a minimum level should only be used when the rectangle of the imagery is small
     * enough that the number of tiles at the minimum level is small.  An imagery
     * provider with more than a few tiles at the minimum level will lead to
     * rendering problems.
     * @memberof IonImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "minimumLevel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.minimumLevel;
      },
    },

    /**
     * Gets the tiling scheme used by the provider.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tilingScheme must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.tilingScheme;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "tileDiscardPolicy must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof IonImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery. This function should
     * not be called before {@link IonImageryProvider#ready} returns true.
     * @memberof IonImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "credit must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.credit;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof IonImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        //>>includeStart('debug', pragmas.debug);
        if (!this._ready) {
          throw new DeveloperError(
            "hasAlphaChannel must not be called before the imagery provider is ready."
          );
        }
        //>>includeEnd('debug');
        return this._imageryProvider.hasAlphaChannel;
      },

      /**
       * Gets the proxy used by this provider.
       * @memberof IonImageryProvider.prototype
       * @type {Proxy}
       * @readonly
       * @default undefined
       */
      proxy: {
        get: function () {
          return undefined;
        },
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   * @function
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  IonImageryProvider.prototype.getTileCredits = function (x, y, level) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "getTileCredits must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');

    var innerCredits = this._imageryProvider.getTileCredits(x, y, level);
    if (!defined(innerCredits)) {
      return this._tileCredits;
    }

    return this._tileCredits.concat(innerCredits);
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link IonImageryProvider#ready} returns true.
   * @function
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  IonImageryProvider.prototype.requestImage = function (x, y, level, request) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "requestImage must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');
    return this._imageryProvider.requestImage(x, y, level, request);
  };

  /**
   * Asynchronously determines what features, if any, are located at a given longitude and latitude within
   * a tile.  This function should not be called before {@link IonImageryProvider#ready} returns true.
   * This function is optional, so it may not exist on all ImageryProviders.
   *
   * @function
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   *
   * @exception {DeveloperError} <code>pickFeatures</code> must not be called before the imagery provider is ready.
   */
  IonImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!this._ready) {
      throw new DeveloperError(
        "pickFeatures must not be called before the imagery provider is ready."
      );
    }
    //>>includeEnd('debug');
    return this._imageryProvider.pickFeatures(x, y, level, longitude, latitude);
  };

  //exposed for testing
  IonImageryProvider._endpointCache = {};

  // Note, these values map directly to ion asset ids.

  /**
   * The types of imagery provided by {@link createWorldImagery}.
   *
   * @enum {Number}
   */
  var IonWorldImageryStyle = {
    /**
     * Aerial imagery.
     *
     * @type {Number}
     * @constant
     */
    AERIAL: 2,

    /**
     * Aerial imagery with a road overlay.
     *
     * @type {Number}
     * @constant
     */
    AERIAL_WITH_LABELS: 3,

    /**
     * Roads without additional imagery.
     *
     * @type {Number}
     * @constant
     */
    ROAD: 4,
  };
  var IonWorldImageryStyle$1 = Object.freeze(IonWorldImageryStyle);

  /**
   *
   * @private
   * @constructor
   */
  function JobTypeBudget(total) {
    /**
     * Total budget, in milliseconds, allowed for one frame
     */
    this._total = total;

    /**
     * Time, in milliseconds, used so far during this frame
     */
    this.usedThisFrame = 0.0;

    /**
     * Time, in milliseconds, that other job types stole this frame
     */
    this.stolenFromMeThisFrame = 0.0;

    /**
     * Indicates if this job type was starved this frame, i.e., a job
     * tried to run but didn't have budget
     */
    this.starvedThisFrame = false;

    /**
     * Indicates if this job was starved last frame.  This prevents it
     * from being stolen from this frame.
     */
    this.starvedLastFrame = false;
  }

  Object.defineProperties(JobTypeBudget.prototype, {
    total: {
      get: function () {
        return this._total;
      },
    },
  });

  /**
   * Engine for time slicing jobs during a frame to amortize work over multiple frames.  This supports:
   * <ul>
   *   <li>
   *     Separate budgets for different job types, e.g., texture, shader program, and buffer creation.  This
   *     allows all job types to make progress each frame.
   *   </li>
   *   <li>
   *     Stealing from other jobs type budgets if they were not exhausted in the previous frame.  This allows
   *     using the entire budget for all job types each frame even if, for example, all the jobs are the same type.
   *   </li>
   *   <li>
   *     Guaranteed progress on all job types each frame, even if it means exceeding the total budget for the frame.
   *     This prevents, for example, several expensive texture uploads over many frames from prevent a shader compile.
   *   </li>
   * </ul>
   *
   * @private
   */
  function JobScheduler(budgets) {
    //>>includeStart('debug', pragmas.debug);
    if (defined(budgets) && budgets.length !== JobType$1.NUMBER_OF_JOB_TYPES) {
      throw new DeveloperError(
        "A budget must be specified for each job type; budgets.length should equal JobType.NUMBER_OF_JOB_TYPES."
      );
    }
    //>>includeEnd('debug');

    // Total for defaults is half of of one frame at 10 fps
    var jobBudgets = new Array(JobType$1.NUMBER_OF_JOB_TYPES);
    jobBudgets[JobType$1.TEXTURE] = new JobTypeBudget(
      defined(budgets) ? budgets[JobType$1.TEXTURE] : 10.0
    );
    // On cache miss, this most likely only allows one shader compile per frame
    jobBudgets[JobType$1.PROGRAM] = new JobTypeBudget(
      defined(budgets) ? budgets[JobType$1.PROGRAM] : 10.0
    );
    jobBudgets[JobType$1.BUFFER] = new JobTypeBudget(
      defined(budgets) ? budgets[JobType$1.BUFFER] : 30.0
    );

    var length = jobBudgets.length;
    var i;

    var totalBudget = 0.0;
    for (i = 0; i < length; ++i) {
      totalBudget += jobBudgets[i].total;
    }

    var executedThisFrame = new Array(length);
    for (i = 0; i < length; ++i) {
      executedThisFrame[i] = false;
    }

    this._totalBudget = totalBudget;
    this._totalUsedThisFrame = 0.0;
    this._budgets = jobBudgets;
    this._executedThisFrame = executedThisFrame;
  }

  // For unit testing
  JobScheduler.getTimestamp = getTimestamp$1;

  Object.defineProperties(JobScheduler.prototype, {
    totalBudget: {
      get: function () {
        return this._totalBudget;
      },
    },
  });

  JobScheduler.prototype.disableThisFrame = function () {
    // Prevent jobs from running this frame
    this._totalUsedThisFrame = this._totalBudget;
  };

  JobScheduler.prototype.resetBudgets = function () {
    var budgets = this._budgets;
    var length = budgets.length;
    for (var i = 0; i < length; ++i) {
      var budget = budgets[i];
      budget.starvedLastFrame = budget.starvedThisFrame;
      budget.starvedThisFrame = false;
      budget.usedThisFrame = 0.0;
      budget.stolenFromMeThisFrame = 0.0;
    }
    this._totalUsedThisFrame = 0.0;
  };

  JobScheduler.prototype.execute = function (job, jobType) {
    var budgets = this._budgets;
    var budget = budgets[jobType];

    // This ensures each job type makes progress each frame by executing at least once
    var progressThisFrame = this._executedThisFrame[jobType];

    if (this._totalUsedThisFrame >= this._totalBudget && progressThisFrame) {
      // No budget left this frame for jobs of any type
      budget.starvedThisFrame = true;
      return false;
    }

    var stolenBudget;

    if (budget.usedThisFrame + budget.stolenFromMeThisFrame >= budget.total) {
      // No budget remaining for jobs of this type. Try to steal from other job types.
      var length = budgets.length;
      var i;
      for (i = 0; i < length; ++i) {
        stolenBudget = budgets[i];

        // Steal from this budget if it has time left and it wasn't starved last fame
        if (
          stolenBudget.usedThisFrame + stolenBudget.stolenFromMeThisFrame <
            stolenBudget.total &&
          !stolenBudget.starvedLastFrame
        ) {
          break;
        }
      }

      if (i === length && progressThisFrame) {
        // No other job types can give up their budget this frame, and
        // this job type already progressed this frame
        return false;
      }

      if (progressThisFrame) {
        // It is considered "starved" even if it executes using stolen time so that
        // next frame, no other job types can steal time from it.
        budget.starvedThisFrame = true;
      }
    }

    var startTime = JobScheduler.getTimestamp();
    job.execute();
    var duration = JobScheduler.getTimestamp() - startTime;

    // Track both time remaining for this job type and all jobs
    // so budget stealing does send us way over the total budget.
    this._totalUsedThisFrame += duration;

    if (stolenBudget) {
      stolenBudget.stolenFromMeThisFrame += duration;
    } else {
      budget.usedThisFrame += duration;
    }
    this._executedThisFrame[jobType] = true;

    return true;
  };

  /**
   * A light source. This type describes an interface and is not intended to be instantiated directly.
   *
   * @alias Light
   * @constructor
   *
   * @see DirectionalLight
   * @see SunLight
   */
  function Light() {}

  Object.defineProperties(Light.prototype, {
    /**
     * The color of the light.
     * @memberof Light.prototype
     * @type {Color}
     */
    color: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * The intensity of the light.
     * @memberof Light.prototype
     * @type {Number}
     */
    intensity: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  var trailingSlashRegex$1 = /\/$/;
  var defaultCredit$2 = new Credit(
    '&copy; <a href="https://www.mapbox.com/about/maps/">Mapbox</a> &copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a> <strong><a href="https://www.mapbox.com/map-feedback/">Improve this map</a></strong>'
  );

  /**
   * @typedef {Object} MapboxStyleImageryProvider.ConstructorOptions
   *
   * Initialization options for the MapboxStyleImageryProvider constructor
   *
   * @property {Resource|String} [url='https://api.mapbox.com/styles/v1/'] The Mapbox server url.
   * @property {String} [username='mapbox'] The username of the map account.
   * @property {String} styleId The Mapbox Style ID.
   * @property {String} accessToken The public access token for the imagery.
   * @property {Number} [tilesize=512] The size of the image tiles.
   * @property {Boolean} [scaleFactor] Determines if tiles are rendered at a @2x scale factor.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.  Take care when specifying
   *                 this that the number of tiles at the minimum level is small, such as four or less.  A larger number is likely
   *                 to result in rendering problems.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle, in radians, covered by the image.
   * @property {Credit|String} [credit] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * Provides tiled imagery hosted by Mapbox.
   *
   * @alias MapboxStyleImageryProvider
   * @constructor
   *
   * @param {MapboxStyleImageryProvider.ConstructorOptions} options Object describing initialization options
   *
   * @example
   * // Mapbox style provider
   * var mapbox = new Cesium.MapboxStyleImageryProvider({
   *     styleId: 'streets-v11',
   *     accessToken: 'thisIsMyAccessToken'
   * });
   *
   * @see {@link https://docs.mapbox.com/api/maps/#styles}
   * @see {@link https://docs.mapbox.com/api/#access-tokens-and-token-scopes}
   */
  function MapboxStyleImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var styleId = options.styleId;
    //>>includeStart('debug', pragmas.debug);
    if (!defined(styleId)) {
      throw new DeveloperError("options.styleId is required.");
    }
    //>>includeEnd('debug');

    var accessToken = MapboxApi.getAccessToken(options.accessToken);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(accessToken)) {
      throw new DeveloperError("options.accessToken is required.");
    }
    //>>includeEnd('debug');

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;

    var resource = Resource.createIfNeeded(
      defaultValue(options.url, "https://api.mapbox.com/styles/v1/")
    );

    this._styleId = styleId;
    this._accessToken = accessToken;

    var tilesize = defaultValue(options.tilesize, 512);
    this._tilesize = tilesize;

    var username = defaultValue(options.username, "mapbox");
    this._username = username;

    var scaleFactor = defined(options.scaleFactor) ? "@2x" : "";

    var templateUrl = resource.getUrlComponent();
    if (!trailingSlashRegex$1.test(templateUrl)) {
      templateUrl += "/";
    }
    templateUrl +=
      this._username +
      "/" +
      styleId +
      "/tiles/" +
      this._tilesize +
      "/{z}/{x}/{y}" +
      scaleFactor;
    resource.url = templateUrl;

    resource.setQueryParameters({
      access_token: accessToken,
    });

    var credit;
    if (defined(options.credit)) {
      credit = options.credit;
      if (typeof credit === "string") {
        credit = new Credit(credit);
      }
    } else {
      credit = defaultCredit$2;
    }

    this._resource = resource;
    this._imageryProvider = new UrlTemplateImageryProvider({
      url: resource,
      credit: credit,
      ellipsoid: options.ellipsoid,
      minimumLevel: options.minimumLevel,
      maximumLevel: options.maximumLevel,
      rectangle: options.rectangle,
    });
  }

  Object.defineProperties(MapboxStyleImageryProvider.prototype, {
    /**
     * Gets the URL of the Mapbox server.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {String}
     * @readonly
     */
    url: {
      get: function () {
        return this._imageryProvider.url;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._imageryProvider.ready;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._imageryProvider.readyPromise;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by the instance.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._imageryProvider.rectangle;
      },
    },

    /**
     * Gets the width of each tile, in pixels.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        return this._imageryProvider.tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        return this._imageryProvider.tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        return this._imageryProvider.maximumLevel;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true. Generally,
     * a minimum level should only be used when the rectangle of the imagery is small
     * enough that the number of tiles at the minimum level is small.  An imagery
     * provider with more than a few tiles at the minimum level will lead to
     * rendering problems.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        return this._imageryProvider.minimumLevel;
      },
    },

    /**
     * Gets the tiling scheme used by the provider.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        return this._imageryProvider.tilingScheme;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        return this._imageryProvider.tileDiscardPolicy;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error..  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._imageryProvider.errorEvent;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery. This function should
     * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return this._imageryProvider.credit;
      },
    },

    /**
     * Gets the proxy used by this provider.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return this._imageryProvider.proxy;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  When this property is false, memory usage
     * and texture upload time are reduced.
     * @memberof MapboxStyleImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return this._imageryProvider.hasAlphaChannel;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  MapboxStyleImageryProvider.prototype.getTileCredits = function (x, y, level) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   *
   * @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
   */
  MapboxStyleImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    return this._imageryProvider.requestImage(x, y, level, request);
  };

  /**
   * Asynchronously determines what features, if any, are located at a given longitude and latitude within
   * a tile.  This function should not be called before {@link MapboxStyleImageryProvider#ready} returns true.
   * This function is optional, so it may not exist on all ImageryProviders.
   *
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   *
   * @exception {DeveloperError} <code>pickFeatures</code> must not be called before the imagery provider is ready.
   */
  MapboxStyleImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return this._imageryProvider.pickFeatures(x, y, level, longitude, latitude);
  };

  // Exposed for tests
  MapboxStyleImageryProvider._defaultCredit = defaultCredit$2;

  /**
   * Draws the Moon in 3D.
   * @alias Moon
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.show=true] Determines whether the moon will be rendered.
   * @param {String} [options.textureUrl=buildModuleUrl('Assets/Textures/moonSmall.jpg')] The moon texture.
   * @param {Ellipsoid} [options.ellipsoid=Ellipsoid.MOON] The moon ellipsoid.
   * @param {Boolean} [options.onlySunLighting=true] Use the sun as the only light source.
   *
   *
   * @example
   * scene.moon = new Cesium.Moon();
   *
   * @see Scene#moon
   */
  function Moon(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var url = options.textureUrl;
    if (!defined(url)) {
      url = buildModuleUrl("Assets/Textures/moonSmall.jpg");
    }

    /**
     * Determines if the moon will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * The moon texture.
     * @type {String}
     * @default buildModuleUrl('Assets/Textures/moonSmall.jpg')
     */
    this.textureUrl = url;

    this._ellipsoid = defaultValue(options.ellipsoid, Ellipsoid.MOON);

    /**
     * Use the sun as the only light source.
     * @type {Boolean}
     * @default true
     */
    this.onlySunLighting = defaultValue(options.onlySunLighting, true);

    this._ellipsoidPrimitive = new EllipsoidPrimitive({
      radii: this.ellipsoid.radii,
      material: Material.fromType(Material.ImageType),
      depthTestEnabled: false,
      _owner: this,
    });
    this._ellipsoidPrimitive.material.translucent = false;

    this._axes = new IauOrientationAxes();
  }

  Object.defineProperties(Moon.prototype, {
    /**
     * Get the ellipsoid that defines the shape of the moon.
     *
     * @memberof Moon.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     *
     * @default {@link Ellipsoid.MOON}
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
  });

  var icrfToFixed = new Matrix3();
  var rotationScratch$1 = new Matrix3();
  var translationScratch = new Cartesian3();
  var scratchCommandList$1 = [];

  /**
   * @private
   */
  Moon.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    var ellipsoidPrimitive = this._ellipsoidPrimitive;
    ellipsoidPrimitive.material.uniforms.image = this.textureUrl;
    ellipsoidPrimitive.onlySunLighting = this.onlySunLighting;

    var date = frameState.time;
    if (!defined(Transforms.computeIcrfToFixedMatrix(date, icrfToFixed))) {
      Transforms.computeTemeToPseudoFixedMatrix(date, icrfToFixed);
    }

    var rotation = this._axes.evaluate(date, rotationScratch$1);
    Matrix3.transpose(rotation, rotation);
    Matrix3.multiply(icrfToFixed, rotation, rotation);

    var translation = Simon1994PlanetaryPositions.computeMoonPositionInEarthInertialFrame(
      date,
      translationScratch
    );
    Matrix3.multiplyByVector(icrfToFixed, translation, translation);

    Matrix4.fromRotationTranslation(
      rotation,
      translation,
      ellipsoidPrimitive.modelMatrix
    );

    var savedCommandList = frameState.commandList;
    frameState.commandList = scratchCommandList$1;
    scratchCommandList$1.length = 0;
    ellipsoidPrimitive.update(frameState);
    frameState.commandList = savedCommandList;
    return scratchCommandList$1.length === 1 ? scratchCommandList$1[0] : undefined;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Moon#destroy
   */
  Moon.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * moon = moon && moon.destroy();
   *
   * @see Moon#isDestroyed
   */
  Moon.prototype.destroy = function () {
    this._ellipsoidPrimitive =
      this._ellipsoidPrimitive && this._ellipsoidPrimitive.destroy();
    return destroyObject(this);
  };

  /**
   * A {@link TileDiscardPolicy} specifying that tile images should never be discard.
   *
   * @alias NeverTileDiscardPolicy
   * @constructor
   *
   * @see DiscardMissingTileImagePolicy
   */
  function NeverTileDiscardPolicy(options) {}

  /**
   * Determines if the discard policy is ready to process images.
   * @returns {Boolean} True if the discard policy is ready to process images; otherwise, false.
   */
  NeverTileDiscardPolicy.prototype.isReady = function () {
    return true;
  };

  /**
   * Given a tile image, decide whether to discard that image.
   *
   * @param {HTMLImageElement} image An image to test.
   * @returns {Boolean} True if the image should be discarded; otherwise, false.
   */
  NeverTileDiscardPolicy.prototype.shouldDiscardImage = function (image) {
    return false;
  };

  //This file is automatically rebuilt by the Cesium build process.
  var AdjustTranslucentFS = "#ifdef MRT\n\
#extension GL_EXT_draw_buffers : enable\n\
#endif\n\
uniform vec4 u_bgColor;\n\
uniform sampler2D u_depthTexture;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
if (texture2D(u_depthTexture, v_textureCoordinates).r < 1.0)\n\
{\n\
#ifdef MRT\n\
gl_FragData[0] = u_bgColor;\n\
gl_FragData[1] = vec4(u_bgColor.a);\n\
#else\n\
gl_FragColor = u_bgColor;\n\
#endif\n\
return;\n\
}\n\
discard;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var CompositeOITFS = "uniform sampler2D u_opaque;\n\
uniform sampler2D u_accumulation;\n\
uniform sampler2D u_revealage;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
vec4 opaque = texture2D(u_opaque, v_textureCoordinates);\n\
vec4 accum = texture2D(u_accumulation, v_textureCoordinates);\n\
float r = texture2D(u_revealage, v_textureCoordinates).r;\n\
#ifdef MRT\n\
vec4 transparent = vec4(accum.rgb / clamp(r, 1e-4, 5e4), accum.a);\n\
#else\n\
vec4 transparent = vec4(accum.rgb / clamp(accum.a, 1e-4, 5e4), r);\n\
#endif\n\
gl_FragColor = (1.0 - transparent.a) * transparent + transparent.a * opaque;\n\
if (opaque != czm_backgroundColor)\n\
{\n\
gl_FragColor.a = 1.0;\n\
}\n\
}\n\
";

  /**
   * @private
   */
  function OIT(context) {
    // We support multipass for the Chrome D3D9 backend and ES 2.0 on mobile.
    this._translucentMultipassSupport = false;
    this._translucentMRTSupport = false;

    var extensionsSupported = context.colorBufferFloat && context.depthTexture;
    this._translucentMRTSupport = context.drawBuffers && extensionsSupported;
    this._translucentMultipassSupport =
      !this._translucentMRTSupport && extensionsSupported;

    this._opaqueFBO = undefined;
    this._opaqueTexture = undefined;
    this._depthStencilTexture = undefined;

    this._accumulationTexture = undefined;

    this._translucentFBO = undefined;
    this._alphaFBO = undefined;

    this._adjustTranslucentFBO = undefined;
    this._adjustAlphaFBO = undefined;

    this._opaqueClearCommand = new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 0.0),
      owner: this,
    });
    this._translucentMRTClearCommand = new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 1.0),
      owner: this,
    });
    this._translucentMultipassClearCommand = new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 0.0),
      owner: this,
    });
    this._alphaClearCommand = new ClearCommand({
      color: new Color(1.0, 1.0, 1.0, 1.0),
      owner: this,
    });

    this._translucentRenderStateCache = {};
    this._alphaRenderStateCache = {};

    this._compositeCommand = undefined;
    this._adjustTranslucentCommand = undefined;
    this._adjustAlphaCommand = undefined;

    this._viewport = new BoundingRectangle();
    this._rs = undefined;

    this._useScissorTest = false;
    this._scissorRectangle = undefined;

    this._useHDR = false;
  }

  function destroyTextures$1(oit) {
    oit._accumulationTexture =
      oit._accumulationTexture &&
      !oit._accumulationTexture.isDestroyed() &&
      oit._accumulationTexture.destroy();
    oit._revealageTexture =
      oit._revealageTexture &&
      !oit._revealageTexture.isDestroyed() &&
      oit._revealageTexture.destroy();
  }

  function destroyFramebuffers$2(oit) {
    oit._translucentFBO =
      oit._translucentFBO &&
      !oit._translucentFBO.isDestroyed() &&
      oit._translucentFBO.destroy();
    oit._alphaFBO =
      oit._alphaFBO && !oit._alphaFBO.isDestroyed() && oit._alphaFBO.destroy();
    oit._adjustTranslucentFBO =
      oit._adjustTranslucentFBO &&
      !oit._adjustTranslucentFBO.isDestroyed() &&
      oit._adjustTranslucentFBO.destroy();
    oit._adjustAlphaFBO =
      oit._adjustAlphaFBO &&
      !oit._adjustAlphaFBO.isDestroyed() &&
      oit._adjustAlphaFBO.destroy();
  }

  function destroyResources$1(oit) {
    destroyTextures$1(oit);
    destroyFramebuffers$2(oit);
  }

  function updateTextures(oit, context, width, height) {
    destroyTextures$1(oit);

    oit._accumulationTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.FLOAT,
    });

    // Use zeroed arraybuffer instead of null to initialize texture
    // to workaround Firefox. Only needed for the second color attachment.
    var source = new Float32Array(width * height * 4);
    oit._revealageTexture = new Texture({
      context: context,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.FLOAT,
      source: {
        arrayBufferView: source,
        width: width,
        height: height,
      },
      flipY: false,
    });
  }

  function updateFramebuffers$1(oit, context) {
    destroyFramebuffers$2(oit);

    var completeFBO = WebGLConstants$1.FRAMEBUFFER_COMPLETE;
    var supported = true;

    // if MRT is supported, attempt to make an FBO with multiple color attachments
    if (oit._translucentMRTSupport) {
      oit._translucentFBO = new Framebuffer({
        context: context,
        colorTextures: [oit._accumulationTexture, oit._revealageTexture],
        depthStencilTexture: oit._depthStencilTexture,
        destroyAttachments: false,
      });
      oit._adjustTranslucentFBO = new Framebuffer({
        context: context,
        colorTextures: [oit._accumulationTexture, oit._revealageTexture],
        destroyAttachments: false,
      });

      if (
        oit._translucentFBO.status !== completeFBO ||
        oit._adjustTranslucentFBO.status !== completeFBO
      ) {
        destroyFramebuffers$2(oit);
        oit._translucentMRTSupport = false;
      }
    }

    // either MRT isn't supported or FBO creation failed, attempt multipass
    if (!oit._translucentMRTSupport) {
      oit._translucentFBO = new Framebuffer({
        context: context,
        colorTextures: [oit._accumulationTexture],
        depthStencilTexture: oit._depthStencilTexture,
        destroyAttachments: false,
      });
      oit._alphaFBO = new Framebuffer({
        context: context,
        colorTextures: [oit._revealageTexture],
        depthStencilTexture: oit._depthStencilTexture,
        destroyAttachments: false,
      });
      oit._adjustTranslucentFBO = new Framebuffer({
        context: context,
        colorTextures: [oit._accumulationTexture],
        destroyAttachments: false,
      });
      oit._adjustAlphaFBO = new Framebuffer({
        context: context,
        colorTextures: [oit._revealageTexture],
        destroyAttachments: false,
      });

      var translucentComplete = oit._translucentFBO.status === completeFBO;
      var alphaComplete = oit._alphaFBO.status === completeFBO;
      var adjustTranslucentComplete =
        oit._adjustTranslucentFBO.status === completeFBO;
      var adjustAlphaComplete = oit._adjustAlphaFBO.status === completeFBO;
      if (
        !translucentComplete ||
        !alphaComplete ||
        !adjustTranslucentComplete ||
        !adjustAlphaComplete
      ) {
        destroyResources$1(oit);
        oit._translucentMultipassSupport = false;
        supported = false;
      }
    }

    return supported;
  }

  OIT.prototype.update = function (context, passState, framebuffer, useHDR) {
    if (!this.isSupported()) {
      return;
    }

    this._opaqueFBO = framebuffer;
    this._opaqueTexture = framebuffer.getColorTexture(0);
    this._depthStencilTexture = framebuffer.depthStencilTexture;

    var width = this._opaqueTexture.width;
    var height = this._opaqueTexture.height;

    var accumulationTexture = this._accumulationTexture;
    var textureChanged =
      !defined(accumulationTexture) ||
      accumulationTexture.width !== width ||
      accumulationTexture.height !== height ||
      useHDR !== this._useHDR;
    if (textureChanged) {
      updateTextures(this, context, width, height);
    }

    if (!defined(this._translucentFBO) || textureChanged) {
      if (!updateFramebuffers$1(this, context)) {
        // framebuffer creation failed
        return;
      }
    }

    this._useHDR = useHDR;

    var that = this;
    var fs;
    var uniformMap;

    if (!defined(this._compositeCommand)) {
      fs = new ShaderSource({
        sources: [CompositeOITFS],
      });
      if (this._translucentMRTSupport) {
        fs.defines.push("MRT");
      }

      uniformMap = {
        u_opaque: function () {
          return that._opaqueTexture;
        },
        u_accumulation: function () {
          return that._accumulationTexture;
        },
        u_revealage: function () {
          return that._revealageTexture;
        },
      };
      this._compositeCommand = context.createViewportQuadCommand(fs, {
        uniformMap: uniformMap,
        owner: this,
      });
    }

    if (!defined(this._adjustTranslucentCommand)) {
      if (this._translucentMRTSupport) {
        fs = new ShaderSource({
          defines: ["MRT"],
          sources: [AdjustTranslucentFS],
        });

        uniformMap = {
          u_bgColor: function () {
            return that._translucentMRTClearCommand.color;
          },
          u_depthTexture: function () {
            return that._depthStencilTexture;
          },
        };

        this._adjustTranslucentCommand = context.createViewportQuadCommand(fs, {
          uniformMap: uniformMap,
          owner: this,
        });
      } else if (this._translucentMultipassSupport) {
        fs = new ShaderSource({
          sources: [AdjustTranslucentFS],
        });

        uniformMap = {
          u_bgColor: function () {
            return that._translucentMultipassClearCommand.color;
          },
          u_depthTexture: function () {
            return that._depthStencilTexture;
          },
        };

        this._adjustTranslucentCommand = context.createViewportQuadCommand(fs, {
          uniformMap: uniformMap,
          owner: this,
        });

        uniformMap = {
          u_bgColor: function () {
            return that._alphaClearCommand.color;
          },
          u_depthTexture: function () {
            return that._depthStencilTexture;
          },
        };

        this._adjustAlphaCommand = context.createViewportQuadCommand(fs, {
          uniformMap: uniformMap,
          owner: this,
        });
      }
    }

    this._viewport.width = width;
    this._viewport.height = height;

    var useScissorTest = !BoundingRectangle.equals(
      this._viewport,
      passState.viewport
    );
    var updateScissor = useScissorTest !== this._useScissorTest;
    this._useScissorTest = useScissorTest;

    if (!BoundingRectangle.equals(this._scissorRectangle, passState.viewport)) {
      this._scissorRectangle = BoundingRectangle.clone(
        passState.viewport,
        this._scissorRectangle
      );
      updateScissor = true;
    }

    if (
      !defined(this._rs) ||
      !BoundingRectangle.equals(this._viewport, this._rs.viewport) ||
      updateScissor
    ) {
      this._rs = RenderState.fromCache({
        viewport: this._viewport,
        scissorTest: {
          enabled: this._useScissorTest,
          rectangle: this._scissorRectangle,
        },
      });
    }

    if (defined(this._compositeCommand)) {
      this._compositeCommand.renderState = this._rs;
    }

    if (this._adjustTranslucentCommand) {
      this._adjustTranslucentCommand.renderState = this._rs;
    }

    if (defined(this._adjustAlphaCommand)) {
      this._adjustAlphaCommand.renderState = this._rs;
    }
  };

  var translucentMRTBlend = {
    enabled: true,
    color: new Color(0.0, 0.0, 0.0, 0.0),
    equationRgb: BlendEquation$1.ADD,
    equationAlpha: BlendEquation$1.ADD,
    functionSourceRgb: BlendFunction$1.ONE,
    functionDestinationRgb: BlendFunction$1.ONE,
    functionSourceAlpha: BlendFunction$1.ZERO,
    functionDestinationAlpha: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
  };

  var translucentColorBlend = {
    enabled: true,
    color: new Color(0.0, 0.0, 0.0, 0.0),
    equationRgb: BlendEquation$1.ADD,
    equationAlpha: BlendEquation$1.ADD,
    functionSourceRgb: BlendFunction$1.ONE,
    functionDestinationRgb: BlendFunction$1.ONE,
    functionSourceAlpha: BlendFunction$1.ONE,
    functionDestinationAlpha: BlendFunction$1.ONE,
  };

  var translucentAlphaBlend = {
    enabled: true,
    color: new Color(0.0, 0.0, 0.0, 0.0),
    equationRgb: BlendEquation$1.ADD,
    equationAlpha: BlendEquation$1.ADD,
    functionSourceRgb: BlendFunction$1.ZERO,
    functionDestinationRgb: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
    functionSourceAlpha: BlendFunction$1.ZERO,
    functionDestinationAlpha: BlendFunction$1.ONE_MINUS_SOURCE_ALPHA,
  };

  function getTranslucentRenderState$2(
    context,
    translucentBlending,
    cache,
    renderState
  ) {
    var translucentState = cache[renderState.id];
    if (!defined(translucentState)) {
      var rs = RenderState.getState(renderState);
      rs.depthMask = false;
      rs.blending = translucentBlending;

      translucentState = RenderState.fromCache(rs);
      cache[renderState.id] = translucentState;
    }

    return translucentState;
  }

  function getTranslucentMRTRenderState(oit, context, renderState) {
    return getTranslucentRenderState$2(
      context,
      translucentMRTBlend,
      oit._translucentRenderStateCache,
      renderState
    );
  }

  function getTranslucentColorRenderState(oit, context, renderState) {
    return getTranslucentRenderState$2(
      context,
      translucentColorBlend,
      oit._translucentRenderStateCache,
      renderState
    );
  }

  function getTranslucentAlphaRenderState(oit, context, renderState) {
    return getTranslucentRenderState$2(
      context,
      translucentAlphaBlend,
      oit._alphaRenderStateCache,
      renderState
    );
  }

  var mrtShaderSource =
    "    vec3 Ci = czm_gl_FragColor.rgb * czm_gl_FragColor.a;\n" +
    "    float ai = czm_gl_FragColor.a;\n" +
    "    float wzi = czm_alphaWeight(ai);\n" +
    "    gl_FragData[0] = vec4(Ci * wzi, ai);\n" +
    "    gl_FragData[1] = vec4(ai * wzi);\n";

  var colorShaderSource =
    "    vec3 Ci = czm_gl_FragColor.rgb * czm_gl_FragColor.a;\n" +
    "    float ai = czm_gl_FragColor.a;\n" +
    "    float wzi = czm_alphaWeight(ai);\n" +
    "    gl_FragColor = vec4(Ci, ai) * wzi;\n";

  var alphaShaderSource =
    "    float ai = czm_gl_FragColor.a;\n" + "    gl_FragColor = vec4(ai);\n";

  function getTranslucentShaderProgram$1(context, shaderProgram, keyword, source) {
    var shader = context.shaderCache.getDerivedShaderProgram(
      shaderProgram,
      keyword
    );
    if (!defined(shader)) {
      var attributeLocations = shaderProgram._attributeLocations;

      var fs = shaderProgram.fragmentShaderSource.clone();

      fs.sources = fs.sources.map(function (source) {
        source = ShaderSource.replaceMain(source, "czm_translucent_main");
        source = source.replace(/gl_FragColor/g, "czm_gl_FragColor");
        source = source.replace(/\bdiscard\b/g, "czm_discard = true");
        source = source.replace(/czm_phong/g, "czm_translucentPhong");
        return source;
      });

      // Discarding the fragment in main is a workaround for ANGLE D3D9
      // shader compilation errors.

      fs.sources.splice(
        0,
        0,
        (source.indexOf("gl_FragData") !== -1
          ? "#extension GL_EXT_draw_buffers : enable \n"
          : "") +
          "vec4 czm_gl_FragColor;\n" +
          "bool czm_discard = false;\n"
      );

      fs.sources.push(
        "void main()\n" +
          "{\n" +
          "    czm_translucent_main();\n" +
          "    if (czm_discard)\n" +
          "    {\n" +
          "        discard;\n" +
          "    }\n" +
          source +
          "}\n"
      );

      shader = context.shaderCache.createDerivedShaderProgram(
        shaderProgram,
        keyword,
        {
          vertexShaderSource: shaderProgram.vertexShaderSource,
          fragmentShaderSource: fs,
          attributeLocations: attributeLocations,
        }
      );
    }

    return shader;
  }

  function getTranslucentMRTShaderProgram(context, shaderProgram) {
    return getTranslucentShaderProgram$1(
      context,
      shaderProgram,
      "translucentMRT",
      mrtShaderSource
    );
  }

  function getTranslucentColorShaderProgram(context, shaderProgram) {
    return getTranslucentShaderProgram$1(
      context,
      shaderProgram,
      "translucentMultipass",
      colorShaderSource
    );
  }

  function getTranslucentAlphaShaderProgram(context, shaderProgram) {
    return getTranslucentShaderProgram$1(
      context,
      shaderProgram,
      "alphaMultipass",
      alphaShaderSource
    );
  }

  OIT.prototype.createDerivedCommands = function (command, context, result) {
    if (!defined(result)) {
      result = {};
    }

    if (this._translucentMRTSupport) {
      var translucentShader;
      var translucentRenderState;
      if (defined(result.translucentCommand)) {
        translucentShader = result.translucentCommand.shaderProgram;
        translucentRenderState = result.translucentCommand.renderState;
      }

      result.translucentCommand = DrawCommand.shallowClone(
        command,
        result.translucentCommand
      );

      if (
        !defined(translucentShader) ||
        result.shaderProgramId !== command.shaderProgram.id
      ) {
        result.translucentCommand.shaderProgram = getTranslucentMRTShaderProgram(
          context,
          command.shaderProgram
        );
        result.translucentCommand.renderState = getTranslucentMRTRenderState(
          this,
          context,
          command.renderState
        );
        result.shaderProgramId = command.shaderProgram.id;
      } else {
        result.translucentCommand.shaderProgram = translucentShader;
        result.translucentCommand.renderState = translucentRenderState;
      }
    } else {
      var colorShader;
      var colorRenderState;
      var alphaShader;
      var alphaRenderState;
      if (defined(result.translucentCommand)) {
        colorShader = result.translucentCommand.shaderProgram;
        colorRenderState = result.translucentCommand.renderState;
        alphaShader = result.alphaCommand.shaderProgram;
        alphaRenderState = result.alphaCommand.renderState;
      }

      result.translucentCommand = DrawCommand.shallowClone(
        command,
        result.translucentCommand
      );
      result.alphaCommand = DrawCommand.shallowClone(
        command,
        result.alphaCommand
      );

      if (
        !defined(colorShader) ||
        result.shaderProgramId !== command.shaderProgram.id
      ) {
        result.translucentCommand.shaderProgram = getTranslucentColorShaderProgram(
          context,
          command.shaderProgram
        );
        result.translucentCommand.renderState = getTranslucentColorRenderState(
          this,
          context,
          command.renderState
        );
        result.alphaCommand.shaderProgram = getTranslucentAlphaShaderProgram(
          context,
          command.shaderProgram
        );
        result.alphaCommand.renderState = getTranslucentAlphaRenderState(
          this,
          context,
          command.renderState
        );
        result.shaderProgramId = command.shaderProgram.id;
      } else {
        result.translucentCommand.shaderProgram = colorShader;
        result.translucentCommand.renderState = colorRenderState;
        result.alphaCommand.shaderProgram = alphaShader;
        result.alphaCommand.renderState = alphaRenderState;
      }
    }

    return result;
  };

  function executeTranslucentCommandsSortedMultipass(
    oit,
    scene,
    executeFunction,
    passState,
    commands,
    invertClassification
  ) {
    var command;
    var derivedCommand;
    var j;

    var context = scene.context;
    var useLogDepth = scene.frameState.useLogDepth;
    var useHdr = scene._hdr;
    var framebuffer = passState.framebuffer;
    var length = commands.length;

    var lightShadowsEnabled = scene.frameState.shadowState.lightShadowsEnabled;

    passState.framebuffer = oit._adjustTranslucentFBO;
    oit._adjustTranslucentCommand.execute(context, passState);
    passState.framebuffer = oit._adjustAlphaFBO;
    oit._adjustAlphaCommand.execute(context, passState);

    var debugFramebuffer = oit._opaqueFBO;
    passState.framebuffer = oit._translucentFBO;

    for (j = 0; j < length; ++j) {
      command = commands[j];
      command = useLogDepth ? command.derivedCommands.logDepth.command : command;
      command = useHdr ? command.derivedCommands.hdr.command : command;
      derivedCommand =
        lightShadowsEnabled && command.receiveShadows
          ? command.derivedCommands.oit.shadows.translucentCommand
          : command.derivedCommands.oit.translucentCommand;
      executeFunction(
        derivedCommand,
        scene,
        context,
        passState,
        debugFramebuffer
      );
    }

    if (defined(invertClassification)) {
      command = invertClassification.unclassifiedCommand;
      derivedCommand =
        lightShadowsEnabled && command.receiveShadows
          ? command.derivedCommands.oit.shadows.translucentCommand
          : command.derivedCommands.oit.translucentCommand;
      executeFunction(
        derivedCommand,
        scene,
        context,
        passState,
        debugFramebuffer
      );
    }

    passState.framebuffer = oit._alphaFBO;

    for (j = 0; j < length; ++j) {
      command = commands[j];
      command = useLogDepth ? command.derivedCommands.logDepth.command : command;
      command = useHdr ? command.derivedCommands.hdr.command : command;
      derivedCommand =
        lightShadowsEnabled && command.receiveShadows
          ? command.derivedCommands.oit.shadows.alphaCommand
          : command.derivedCommands.oit.alphaCommand;
      executeFunction(
        derivedCommand,
        scene,
        context,
        passState,
        debugFramebuffer
      );
    }

    if (defined(invertClassification)) {
      command = invertClassification.unclassifiedCommand;
      derivedCommand =
        lightShadowsEnabled && command.receiveShadows
          ? command.derivedCommands.oit.shadows.alphaCommand
          : command.derivedCommands.oit.alphaCommand;
      executeFunction(
        derivedCommand,
        scene,
        context,
        passState,
        debugFramebuffer
      );
    }

    passState.framebuffer = framebuffer;
  }

  function executeTranslucentCommandsSortedMRT(
    oit,
    scene,
    executeFunction,
    passState,
    commands,
    invertClassification
  ) {
    var context = scene.context;
    var useLogDepth = scene.frameState.useLogDepth;
    var useHdr = scene._hdr;
    var framebuffer = passState.framebuffer;
    var length = commands.length;

    var lightShadowsEnabled = scene.frameState.shadowState.lightShadowsEnabled;

    passState.framebuffer = oit._adjustTranslucentFBO;
    oit._adjustTranslucentCommand.execute(context, passState);

    var debugFramebuffer = oit._opaqueFBO;
    passState.framebuffer = oit._translucentFBO;

    var command;
    var derivedCommand;

    for (var j = 0; j < length; ++j) {
      command = commands[j];
      command = useLogDepth ? command.derivedCommands.logDepth.command : command;
      command = useHdr ? command.derivedCommands.hdr.command : command;
      derivedCommand =
        lightShadowsEnabled && command.receiveShadows
          ? command.derivedCommands.oit.shadows.translucentCommand
          : command.derivedCommands.oit.translucentCommand;
      executeFunction(
        derivedCommand,
        scene,
        context,
        passState,
        debugFramebuffer
      );
    }

    if (defined(invertClassification)) {
      command = invertClassification.unclassifiedCommand;
      derivedCommand =
        lightShadowsEnabled && command.receiveShadows
          ? command.derivedCommands.oit.shadows.translucentCommand
          : command.derivedCommands.oit.translucentCommand;
      executeFunction(
        derivedCommand,
        scene,
        context,
        passState,
        debugFramebuffer
      );
    }

    passState.framebuffer = framebuffer;
  }

  OIT.prototype.executeCommands = function (
    scene,
    executeFunction,
    passState,
    commands,
    invertClassification
  ) {
    if (this._translucentMRTSupport) {
      executeTranslucentCommandsSortedMRT(
        this,
        scene,
        executeFunction,
        passState,
        commands,
        invertClassification
      );
      return;
    }

    executeTranslucentCommandsSortedMultipass(
      this,
      scene,
      executeFunction,
      passState,
      commands,
      invertClassification
    );
  };

  OIT.prototype.execute = function (context, passState) {
    this._compositeCommand.execute(context, passState);
  };

  OIT.prototype.clear = function (context, passState, clearColor) {
    var framebuffer = passState.framebuffer;

    passState.framebuffer = this._opaqueFBO;
    Color.clone(clearColor, this._opaqueClearCommand.color);
    this._opaqueClearCommand.execute(context, passState);

    passState.framebuffer = this._translucentFBO;
    var translucentClearCommand = this._translucentMRTSupport
      ? this._translucentMRTClearCommand
      : this._translucentMultipassClearCommand;
    translucentClearCommand.execute(context, passState);

    if (this._translucentMultipassSupport) {
      passState.framebuffer = this._alphaFBO;
      this._alphaClearCommand.execute(context, passState);
    }

    passState.framebuffer = framebuffer;
  };

  OIT.prototype.isSupported = function () {
    return this._translucentMRTSupport || this._translucentMultipassSupport;
  };

  OIT.prototype.isDestroyed = function () {
    return false;
  };

  OIT.prototype.destroy = function () {
    destroyResources$1(this);

    if (defined(this._compositeCommand)) {
      this._compositeCommand.shaderProgram =
        this._compositeCommand.shaderProgram &&
        this._compositeCommand.shaderProgram.destroy();
    }

    if (defined(this._adjustTranslucentCommand)) {
      this._adjustTranslucentCommand.shaderProgram =
        this._adjustTranslucentCommand.shaderProgram &&
        this._adjustTranslucentCommand.shaderProgram.destroy();
    }

    if (defined(this._adjustAlphaCommand)) {
      this._adjustAlphaCommand.shaderProgram =
        this._adjustAlphaCommand.shaderProgram &&
        this._adjustAlphaCommand.shaderProgram.destroy();
    }

    return destroyObject(this);
  };

  var defaultCredit$3 = new Credit(
    "MapQuest, Open Street Map and contributors, CC-BY-SA"
  );

  /**
   * @typedef {Object} OpenStreetMapImageryProvider.ConstructorOptions
   *
   * Initialization options for the OpenStreetMapImageryProvider constructor
   *
   * @property {String} [url='https://a.tile.openstreetmap.org'] The OpenStreetMap server url.
   * @property {String} [fileExtension='png'] The file extension for images on the server.
   * @property {Rectangle} [rectangle=Rectangle.MAX_VALUE] The rectangle of the layer.
   * @property {Number} [minimumLevel=0] The minimum level-of-detail supported by the imagery provider.
   * @property {Number} [maximumLevel] The maximum level-of-detail supported by the imagery provider, or undefined if there is no limit.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If not specified, the WGS84 ellipsoid is used.
   * @property {Credit|String} [credit='MapQuest, Open Street Map and contributors, CC-BY-SA'] A credit for the data source, which is displayed on the canvas.
   */

  /**
   * An imagery provider that provides tiled imagery hosted by OpenStreetMap
   * or another provider of Slippy tiles.  The default url connects to OpenStreetMap's volunteer-run
   * servers, so you must conform to their
   * {@link http://wiki.openstreetmap.org/wiki/Tile_usage_policy|Tile Usage Policy}.
   *
   * @alias OpenStreetMapImageryProvider
   * @constructor
   * @extends UrlTemplateImageryProvider
   *
   * @param {OpenStreetMapImageryProvider.ConstructorOptions} options Object describing initialization options
   * @exception {DeveloperError} The rectangle and minimumLevel indicate that there are more than four tiles at the minimum level. Imagery providers with more than four tiles at the minimum level are not supported.
   *
   * @see ArcGisMapServerImageryProvider
   * @see BingMapsImageryProvider
   * @see GoogleEarthEnterpriseMapsProvider
   * @see SingleTileImageryProvider
   * @see TileMapServiceImageryProvider
   * @see WebMapServiceImageryProvider
   * @see WebMapTileServiceImageryProvider
   * @see UrlTemplateImageryProvider
   *
   * @example
   * var osm = new Cesium.OpenStreetMapImageryProvider({
   *     url : 'https://a.tile.openstreetmap.org/'
   * });
   *
   * @see {@link http://wiki.openstreetmap.org/wiki/Main_Page|OpenStreetMap Wiki}
   * @see {@link http://www.w3.org/TR/cors/|Cross-Origin Resource Sharing}
   */
  function OpenStreetMapImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var resource = Resource.createIfNeeded(
      defaultValue(options.url, "https://a.tile.openstreetmap.org/")
    );
    resource.appendForwardSlash();
    resource.url += "{z}/{x}/{y}." + defaultValue(options.fileExtension, "png");

    var tilingScheme = new WebMercatorTilingScheme({
      ellipsoid: options.ellipsoid,
    });

    var tileWidth = 256;
    var tileHeight = 256;

    var minimumLevel = defaultValue(options.minimumLevel, 0);
    var maximumLevel = options.maximumLevel;

    var rectangle = defaultValue(options.rectangle, tilingScheme.rectangle);

    // Check the number of tiles at the minimum level.  If it's more than four,
    // throw an exception, because starting at the higher minimum
    // level will cause too many tiles to be downloaded and rendered.
    var swTile = tilingScheme.positionToTileXY(
      Rectangle.southwest(rectangle),
      minimumLevel
    );
    var neTile = tilingScheme.positionToTileXY(
      Rectangle.northeast(rectangle),
      minimumLevel
    );
    var tileCount =
      (Math.abs(neTile.x - swTile.x) + 1) * (Math.abs(neTile.y - swTile.y) + 1);
    //>>includeStart('debug', pragmas.debug);
    if (tileCount > 4) {
      throw new DeveloperError(
        "The rectangle and minimumLevel indicate that there are " +
          tileCount +
          " tiles at the minimum level. Imagery providers with more than four tiles at the minimum level are not supported."
      );
    }
    //>>includeEnd('debug');

    var credit = defaultValue(options.credit, defaultCredit$3);
    if (typeof credit === "string") {
      credit = new Credit(credit);
    }

    UrlTemplateImageryProvider.call(this, {
      url: resource,
      credit: credit,
      tilingScheme: tilingScheme,
      tileWidth: tileWidth,
      tileHeight: tileHeight,
      minimumLevel: minimumLevel,
      maximumLevel: maximumLevel,
      rectangle: rectangle,
    });
  }

  if (defined(Object.create)) {
    OpenStreetMapImageryProvider.prototype = Object.create(
      UrlTemplateImageryProvider.prototype
    );
    OpenStreetMapImageryProvider.prototype.constructor = OpenStreetMapImageryProvider;
  }

  var defaultSize = new Cartesian2(1.0, 1.0);

  /**
   * A particle emitted by a {@link ParticleSystem}.
   *
   * @alias Particle
   * @constructor
   *
   * @param {Object} options An object with the following properties:
   * @param {Number} [options.mass=1.0] The mass of the particle in kilograms.
   * @param {Cartesian3} [options.position=Cartesian3.ZERO] The initial position of the particle in world coordinates.
   * @param {Cartesian3} [options.velocity=Cartesian3.ZERO] The velocity vector of the particle in world coordinates.
   * @param {Number} [options.life=Number.MAX_VALUE] The life of the particle in seconds.
   * @param {Object} [options.image] The URI, HTMLImageElement, or HTMLCanvasElement to use for the billboard.
   * @param {Color} [options.startColor=Color.WHITE] The color of a particle when it is born.
   * @param {Color} [options.endColor=Color.WHITE] The color of a particle when it dies.
   * @param {Number} [options.startScale=1.0] The scale of the particle when it is born.
   * @param {Number} [options.endScale=1.0] The scale of the particle when it dies.
   * @param {Cartesian2} [options.imageSize=new Cartesian2(1.0, 1.0)] The dimensions, width by height, to scale the particle image in pixels.
   */
  function Particle(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The mass of the particle in kilograms.
     * @type {Number}
     * @default 1.0
     */
    this.mass = defaultValue(options.mass, 1.0);
    /**
     * The positon of the particle in world coordinates.
     * @type {Cartesian3}
     * @default Cartesian3.ZERO
     */
    this.position = Cartesian3.clone(
      defaultValue(options.position, Cartesian3.ZERO)
    );
    /**
     * The velocity of the particle in world coordinates.
     * @type {Cartesian3}
     * @default Cartesian3.ZERO
     */
    this.velocity = Cartesian3.clone(
      defaultValue(options.velocity, Cartesian3.ZERO)
    );
    /**
     * The life of the particle in seconds.
     * @type {Number}
     * @default Number.MAX_VALUE
     */
    this.life = defaultValue(options.life, Number.MAX_VALUE);
    /**
     * The image to use for the particle.
     * @type {Object}
     * @default undefined
     */
    this.image = options.image;
    /**
     * The color of the particle when it is born.
     * @type {Color}
     * @default Color.WHITE
     */
    this.startColor = Color.clone(defaultValue(options.startColor, Color.WHITE));
    /**
     * The color of the particle when it dies.
     * @type {Color}
     * @default Color.WHITE
     */
    this.endColor = Color.clone(defaultValue(options.endColor, Color.WHITE));
    /**
     * the scale of the particle when it is born.
     * @type {Number}
     * @default 1.0
     */
    this.startScale = defaultValue(options.startScale, 1.0);
    /**
     * The scale of the particle when it dies.
     * @type {Number}
     * @default 1.0
     */
    this.endScale = defaultValue(options.endScale, 1.0);
    /**
     * The dimensions, width by height, to scale the particle image in pixels.
     * @type {Cartesian2}
     * @default new Cartesian(1.0, 1.0)
     */
    this.imageSize = Cartesian2.clone(
      defaultValue(options.imageSize, defaultSize)
    );

    this._age = 0.0;
    this._normalizedAge = 0.0;

    // used by ParticleSystem
    this._billboard = undefined;
  }

  Object.defineProperties(Particle.prototype, {
    /**
     * Gets the age of the particle in seconds.
     * @memberof Particle.prototype
     * @type {Number}
     */
    age: {
      get: function () {
        return this._age;
      },
    },
    /**
     * Gets the age normalized to a value in the range [0.0, 1.0].
     * @memberof Particle.prototype
     * @type {Number}
     */
    normalizedAge: {
      get: function () {
        return this._normalizedAge;
      },
    },
  });

  var deltaScratch = new Cartesian3();

  /**
   * @private
   */
  Particle.prototype.update = function (dt, particleUpdateFunction) {
    // Apply the velocity
    Cartesian3.multiplyByScalar(this.velocity, dt, deltaScratch);
    Cartesian3.add(this.position, deltaScratch, this.position);

    // Update any forces.
    if (defined(particleUpdateFunction)) {
      particleUpdateFunction(this, dt);
    }

    // Age the particle
    this._age += dt;

    // Compute the normalized age.
    if (this.life === Number.MAX_VALUE) {
      this._normalizedAge = 0.0;
    } else {
      this._normalizedAge = this._age / this.life;
    }

    // If this particle is older than it's lifespan then die.
    return this._age <= this.life;
  };

  /**
   * Represents a burst of {@link Particle}s from a {@link ParticleSystem} at a given time in the systems lifetime.
   *
   * @alias ParticleBurst
   * @constructor
   *
   * @param {Object} [options] An object with the following properties:
   * @param {Number} [options.time=0.0] The time in seconds after the beginning of the particle system's lifetime that the burst will occur.
   * @param {Number} [options.minimum=0.0] The minimum number of particles emmitted in the burst.
   * @param {Number} [options.maximum=50.0] The maximum number of particles emitted in the burst.
   */
  function ParticleBurst(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * The time in seconds after the beginning of the particle system's lifetime that the burst will occur.
     * @type {Number}
     * @default 0.0
     */
    this.time = defaultValue(options.time, 0.0);
    /**
     * The minimum number of particles emitted.
     * @type {Number}
     * @default 0.0
     */
    this.minimum = defaultValue(options.minimum, 0.0);
    /**
     * The maximum number of particles emitted.
     * @type {Number}
     * @default 50.0
     */
    this.maximum = defaultValue(options.maximum, 50.0);

    this._complete = false;
  }

  Object.defineProperties(ParticleBurst.prototype, {
    /**
     * <code>true</code> if the burst has been completed; <code>false</code> otherwise.
     * @memberof ParticleBurst.prototype
     * @type {Boolean}
     */
    complete: {
      get: function () {
        return this._complete;
      },
    },
  });

  /**
   * <p>
   * An object that initializes a {@link Particle} from a {@link ParticleSystem}.
   * </p>
   * <p>
   * This type describes an interface and is not intended to be instantiated directly.
   * </p>
   *
   * @alias ParticleEmitter
   * @constructor
   *
   * @see BoxEmitter
   * @see CircleEmitter
   * @see ConeEmitter
   * @see SphereEmitter
   */
  function ParticleEmitter(options) {
    //>>includeStart('debug', pragmas.debug);
    throw new DeveloperError(
      "This type should not be instantiated directly.  Instead, use BoxEmitter, CircleEmitter, ConeEmitter or SphereEmitter."
    );
    //>>includeEnd('debug');
  }

  /**
   * Initializes the given {Particle} by setting it's position and velocity.
   *
   * @private
   * @param {Particle} The particle to initialize
   */
  ParticleEmitter.prototype.emit = function (particle) {
    DeveloperError.throwInstantiationError();
  };

  var defaultImageSize = new Cartesian2(1.0, 1.0);

  /**
   * A ParticleSystem manages the updating and display of a collection of particles.
   *
   * @alias ParticleSystem
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.show=true] Whether to display the particle system.
   * @param {ParticleSystem.updateCallback} [options.updateCallback] The callback function to be called each frame to update a particle.
   * @param {ParticleEmitter} [options.emitter=new CircleEmitter(0.5)] The particle emitter for this system.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the particle system from model to world coordinates.
   * @param {Matrix4} [options.emitterModelMatrix=Matrix4.IDENTITY] The 4x4 transformation matrix that transforms the particle system emitter within the particle systems local coordinate system.
   * @param {Number} [options.emissionRate=5] The number of particles to emit per second.
   * @param {ParticleBurst[]} [options.bursts] An array of {@link ParticleBurst}, emitting bursts of particles at periodic times.
   * @param {Boolean} [options.loop=true] Whether the particle system should loop its bursts when it is complete.
   * @param {Number} [options.scale=1.0] Sets the scale to apply to the image of the particle for the duration of its particleLife.
   * @param {Number} [options.startScale] The initial scale to apply to the image of the particle at the beginning of its life.
   * @param {Number} [options.endScale] The final scale to apply to the image of the particle at the end of its life.
   * @param {Color} [options.color=Color.WHITE] Sets the color of a particle for the duration of its particleLife.
   * @param {Color} [options.startColor] The color of the particle at the beginning of its life.
   * @param {Color} [options.endColor] The color of the particle at the end of its life.
   * @param {Object} [options.image] The URI, HTMLImageElement, or HTMLCanvasElement to use for the billboard.
   * @param {Cartesian2} [options.imageSize=new Cartesian2(1.0, 1.0)] If set, overrides the minimumImageSize and maximumImageSize inputs that scale the particle image's dimensions in pixels.
   * @param {Cartesian2} [options.minimumImageSize] Sets the minimum bound, width by height, above which to randomly scale the particle image's dimensions in pixels.
   * @param {Cartesian2} [options.maximumImageSize] Sets the maximum bound, width by height, below which to randomly scale the particle image's dimensions in pixels.
   * @param {Boolean} [options.sizeInMeters] Sets if the size of particles is in meters or pixels. <code>true</code> to size the particles in meters; otherwise, the size is in pixels.
   * @param {Number} [options.speed=1.0] If set, overrides the minimumSpeed and maximumSpeed inputs with this value.
   * @param {Number} [options.minimumSpeed] Sets the minimum bound in meters per second above which a particle's actual speed will be randomly chosen.
   * @param {Number} [options.maximumSpeed] Sets the maximum bound in meters per second below which a particle's actual speed will be randomly chosen.
   * @param {Number} [options.lifetime=Number.MAX_VALUE] How long the particle system will emit particles, in seconds.
   * @param {Number} [options.particleLife=5.0] If set, overrides the minimumParticleLife and maximumParticleLife inputs with this value.
   * @param {Number} [options.minimumParticleLife] Sets the minimum bound in seconds for the possible duration of a particle's life above which a particle's actual life will be randomly chosen.
   * @param {Number} [options.maximumParticleLife] Sets the maximum bound in seconds for the possible duration of a particle's life below which a particle's actual life will be randomly chosen.
   * @param {Number} [options.mass=1.0] Sets the minimum and maximum mass of particles in kilograms.
   * @param {Number} [options.minimumMass] Sets the minimum bound for the mass of a particle in kilograms. A particle's actual mass will be chosen as a random amount above this value.
   * @param {Number} [options.maximumMass] Sets the maximum mass of particles in kilograms. A particle's actual mass will be chosen as a random amount below this value.
   * @tutorial {@link https://cesium.com/docs/tutorials/particle-systems/|Particle Systems Tutorial}
   * @demo {@link https://sandcastle.cesium.com/?src=Particle%20System.html&label=Showcases|Particle Systems Tutorial Demo}
   * @demo {@link https://sandcastle.cesium.com/?src=Particle%20System%20Fireworks.html&label=Showcases|Particle Systems Fireworks Demo}
   */
  function ParticleSystem(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * Whether to display the particle system.
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * An array of force callbacks. The callback is passed a {@link Particle} and the difference from the last time
     * @type {ParticleSystem.updateCallback}
     * @default undefined
     */
    this.updateCallback = options.updateCallback;

    /**
     * Whether the particle system should loop it's bursts when it is complete.
     * @type {Boolean}
     * @default true
     */
    this.loop = defaultValue(options.loop, true);

    /**
     * The URI, HTMLImageElement, or HTMLCanvasElement to use for the billboard.
     * @type {Object}
     * @default undefined
     */
    this.image = defaultValue(options.image, undefined);

    var emitter = options.emitter;
    if (!defined(emitter)) {
      emitter = new CircleEmitter(0.5);
    }
    this._emitter = emitter;

    this._bursts = options.bursts;

    this._modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    this._emitterModelMatrix = Matrix4.clone(
      defaultValue(options.emitterModelMatrix, Matrix4.IDENTITY)
    );
    this._matrixDirty = true;
    this._combinedMatrix = new Matrix4();

    this._startColor = Color.clone(
      defaultValue(options.color, defaultValue(options.startColor, Color.WHITE))
    );
    this._endColor = Color.clone(
      defaultValue(options.color, defaultValue(options.endColor, Color.WHITE))
    );

    this._startScale = defaultValue(
      options.scale,
      defaultValue(options.startScale, 1.0)
    );
    this._endScale = defaultValue(
      options.scale,
      defaultValue(options.endScale, 1.0)
    );

    this._emissionRate = defaultValue(options.emissionRate, 5.0);

    this._minimumSpeed = defaultValue(
      options.speed,
      defaultValue(options.minimumSpeed, 1.0)
    );
    this._maximumSpeed = defaultValue(
      options.speed,
      defaultValue(options.maximumSpeed, 1.0)
    );

    this._minimumParticleLife = defaultValue(
      options.particleLife,
      defaultValue(options.minimumParticleLife, 5.0)
    );
    this._maximumParticleLife = defaultValue(
      options.particleLife,
      defaultValue(options.maximumParticleLife, 5.0)
    );

    this._minimumMass = defaultValue(
      options.mass,
      defaultValue(options.minimumMass, 1.0)
    );
    this._maximumMass = defaultValue(
      options.mass,
      defaultValue(options.maximumMass, 1.0)
    );

    this._minimumImageSize = Cartesian2.clone(
      defaultValue(
        options.imageSize,
        defaultValue(options.minimumImageSize, defaultImageSize)
      )
    );
    this._maximumImageSize = Cartesian2.clone(
      defaultValue(
        options.imageSize,
        defaultValue(options.maximumImageSize, defaultImageSize)
      )
    );

    this._sizeInMeters = defaultValue(options.sizeInMeters, false);

    this._lifetime = defaultValue(options.lifetime, Number.MAX_VALUE);

    this._billboardCollection = undefined;
    this._particles = [];

    // An array of available particles that we can reuse instead of allocating new.
    this._particlePool = [];

    this._previousTime = undefined;
    this._currentTime = 0.0;
    this._carryOver = 0.0;

    this._complete = new Event();
    this._isComplete = false;

    this._updateParticlePool = true;
    this._particleEstimate = 0;
  }

  Object.defineProperties(ParticleSystem.prototype, {
    /**
     * The particle emitter for this
     * @memberof ParticleSystem.prototype
     * @type {ParticleEmitter}
     * @default CircleEmitter
     */
    emitter: {
      get: function () {
        return this._emitter;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');
        this._emitter = value;
      },
    },
    /**
     * An array of {@link ParticleBurst}, emitting bursts of particles at periodic times.
     * @memberof ParticleSystem.prototype
     * @type {ParticleBurst[]}
     * @default undefined
     */
    bursts: {
      get: function () {
        return this._bursts;
      },
      set: function (value) {
        this._bursts = value;
        this._updateParticlePool = true;
      },
    },
    /**
     * The 4x4 transformation matrix that transforms the particle system from model to world coordinates.
     * @memberof ParticleSystem.prototype
     * @type {Matrix4}
     * @default Matrix4.IDENTITY
     */
    modelMatrix: {
      get: function () {
        return this._modelMatrix;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');
        this._matrixDirty =
          this._matrixDirty || !Matrix4.equals(this._modelMatrix, value);
        Matrix4.clone(value, this._modelMatrix);
      },
    },
    /**
     * The 4x4 transformation matrix that transforms the particle system emitter within the particle systems local coordinate system.
     * @memberof ParticleSystem.prototype
     * @type {Matrix4}
     * @default Matrix4.IDENTITY
     */
    emitterModelMatrix: {
      get: function () {
        return this._emitterModelMatrix;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');
        this._matrixDirty =
          this._matrixDirty || !Matrix4.equals(this._emitterModelMatrix, value);
        Matrix4.clone(value, this._emitterModelMatrix);
      },
    },
    /**
     * The color of the particle at the beginning of its life.
     * @memberof ParticleSystem.prototype
     * @type {Color}
     * @default Color.WHITE
     */
    startColor: {
      get: function () {
        return this._startColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');
        Color.clone(value, this._startColor);
      },
    },
    /**
     * The color of the particle at the end of its life.
     * @memberof ParticleSystem.prototype
     * @type {Color}
     * @default Color.WHITE
     */
    endColor: {
      get: function () {
        return this._endColor;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined("value", value);
        //>>includeEnd('debug');
        Color.clone(value, this._endColor);
      },
    },
    /**
     * The initial scale to apply to the image of the particle at the beginning of its life.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 1.0
     */
    startScale: {
      get: function () {
        return this._startScale;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._startScale = value;
      },
    },
    /**
     * The final scale to apply to the image of the particle at the end of its life.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 1.0
     */
    endScale: {
      get: function () {
        return this._endScale;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._endScale = value;
      },
    },
    /**
     * The number of particles to emit per second.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 5
     */
    emissionRate: {
      get: function () {
        return this._emissionRate;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._emissionRate = value;
        this._updateParticlePool = true;
      },
    },
    /**
     * Sets the minimum bound in meters per second above which a particle's actual speed will be randomly chosen.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 1.0
     */
    minimumSpeed: {
      get: function () {
        return this._minimumSpeed;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._minimumSpeed = value;
      },
    },
    /**
     * Sets the maximum bound in meters per second below which a particle's actual speed will be randomly chosen.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 1.0
     */
    maximumSpeed: {
      get: function () {
        return this._maximumSpeed;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._maximumSpeed = value;
      },
    },
    /**
     * Sets the minimum bound in seconds for the possible duration of a particle's life above which a particle's actual life will be randomly chosen.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 5.0
     */
    minimumParticleLife: {
      get: function () {
        return this._minimumParticleLife;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._minimumParticleLife = value;
      },
    },
    /**
     * Sets the maximum bound in seconds for the possible duration of a particle's life below which a particle's actual life will be randomly chosen.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 5.0
     */
    maximumParticleLife: {
      get: function () {
        return this._maximumParticleLife;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._maximumParticleLife = value;
        this._updateParticlePool = true;
      },
    },
    /**
     * Sets the minimum mass of particles in kilograms.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 1.0
     */
    minimumMass: {
      get: function () {
        return this._minimumMass;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._minimumMass = value;
      },
    },
    /**
     * Sets the maximum mass of particles in kilograms.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default 1.0
     */
    maximumMass: {
      get: function () {
        return this._maximumMass;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._maximumMass = value;
      },
    },
    /**
     * Sets the minimum bound, width by height, above which to randomly scale the particle image's dimensions in pixels.
     * @memberof ParticleSystem.prototype
     * @type {Cartesian2}
     * @default new Cartesian2(1.0, 1.0)
     */
    minimumImageSize: {
      get: function () {
        return this._minimumImageSize;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.object("value", value);
        Check.typeOf.number.greaterThanOrEquals("value.x", value.x, 0.0);
        Check.typeOf.number.greaterThanOrEquals("value.y", value.y, 0.0);
        //>>includeEnd('debug');
        this._minimumImageSize = value;
      },
    },
    /**
     * Sets the maximum bound, width by height, below which to randomly scale the particle image's dimensions in pixels.
     * @memberof ParticleSystem.prototype
     * @type {Cartesian2}
     * @default new Cartesian2(1.0, 1.0)
     */
    maximumImageSize: {
      get: function () {
        return this._maximumImageSize;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.object("value", value);
        Check.typeOf.number.greaterThanOrEquals("value.x", value.x, 0.0);
        Check.typeOf.number.greaterThanOrEquals("value.y", value.y, 0.0);
        //>>includeEnd('debug');
        this._maximumImageSize = value;
      },
    },
    /**
     * Gets or sets if the particle size is in meters or pixels. <code>true</code> to size particles in meters; otherwise, the size is in pixels.
     * @memberof ParticleSystem.prototype
     * @type {Boolean}
     * @default false
     */
    sizeInMeters: {
      get: function () {
        return this._sizeInMeters;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.bool("value", value);
        //>>includeEnd('debug');
        this._sizeInMeters = value;
      },
    },
    /**
     * How long the particle system will emit particles, in seconds.
     * @memberof ParticleSystem.prototype
     * @type {Number}
     * @default Number.MAX_VALUE
     */
    lifetime: {
      get: function () {
        return this._lifetime;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThanOrEquals("value", value, 0.0);
        //>>includeEnd('debug');
        this._lifetime = value;
      },
    },
    /**
     * Fires an event when the particle system has reached the end of its lifetime.
     * @memberof ParticleSystem.prototype
     * @type {Event}
     */
    complete: {
      get: function () {
        return this._complete;
      },
    },
    /**
     * When <code>true</code>, the particle system has reached the end of its lifetime; <code>false</code> otherwise.
     * @memberof ParticleSystem.prototype
     * @type {Boolean}
     */
    isComplete: {
      get: function () {
        return this._isComplete;
      },
    },
  });

  function updateParticlePool(system) {
    var emissionRate = system._emissionRate;
    var life = system._maximumParticleLife;

    var burstAmount = 0;
    var bursts = system._bursts;
    if (defined(bursts)) {
      var length = bursts.length;
      for (var i = 0; i < length; ++i) {
        burstAmount += bursts[i].maximum;
      }
    }

    var billboardCollection = system._billboardCollection;
    var image = system.image;

    var particleEstimate = Math.ceil(emissionRate * life + burstAmount);
    var particles = system._particles;
    var particlePool = system._particlePool;
    var numToAdd = Math.max(
      particleEstimate - particles.length - particlePool.length,
      0
    );

    for (var j = 0; j < numToAdd; ++j) {
      var particle = new Particle();
      particle._billboard = billboardCollection.add({
        image: image,
      });
      particlePool.push(particle);
    }

    system._particleEstimate = particleEstimate;
  }

  function getOrCreateParticle(system) {
    // Try to reuse an existing particle from the pool.
    var particle = system._particlePool.pop();
    if (!defined(particle)) {
      // Create a new one
      particle = new Particle();
    }
    return particle;
  }

  function addParticleToPool(system, particle) {
    system._particlePool.push(particle);
  }

  function freeParticlePool(system) {
    var particles = system._particles;
    var particlePool = system._particlePool;
    var billboardCollection = system._billboardCollection;

    var numParticles = particles.length;
    var numInPool = particlePool.length;
    var estimate = system._particleEstimate;

    var start = numInPool - Math.max(estimate - numParticles - numInPool, 0);
    for (var i = start; i < numInPool; ++i) {
      var p = particlePool[i];
      billboardCollection.remove(p._billboard);
    }
    particlePool.length = start;
  }

  function removeBillboard(particle) {
    if (defined(particle._billboard)) {
      particle._billboard.show = false;
    }
  }

  function updateBillboard(system, particle) {
    var billboard = particle._billboard;
    if (!defined(billboard)) {
      billboard = particle._billboard = system._billboardCollection.add({
        image: particle.image,
      });
    }
    billboard.width = particle.imageSize.x;
    billboard.height = particle.imageSize.y;
    billboard.position = particle.position;
    billboard.sizeInMeters = system.sizeInMeters;
    billboard.show = true;

    // Update the color
    var r = CesiumMath.lerp(
      particle.startColor.red,
      particle.endColor.red,
      particle.normalizedAge
    );
    var g = CesiumMath.lerp(
      particle.startColor.green,
      particle.endColor.green,
      particle.normalizedAge
    );
    var b = CesiumMath.lerp(
      particle.startColor.blue,
      particle.endColor.blue,
      particle.normalizedAge
    );
    var a = CesiumMath.lerp(
      particle.startColor.alpha,
      particle.endColor.alpha,
      particle.normalizedAge
    );
    billboard.color = new Color(r, g, b, a);

    // Update the scale
    billboard.scale = CesiumMath.lerp(
      particle.startScale,
      particle.endScale,
      particle.normalizedAge
    );
  }

  function addParticle(system, particle) {
    particle.startColor = Color.clone(system._startColor, particle.startColor);
    particle.endColor = Color.clone(system._endColor, particle.endColor);
    particle.startScale = system._startScale;
    particle.endScale = system._endScale;
    particle.image = system.image;
    particle.life = CesiumMath.randomBetween(
      system._minimumParticleLife,
      system._maximumParticleLife
    );
    particle.mass = CesiumMath.randomBetween(
      system._minimumMass,
      system._maximumMass
    );
    particle.imageSize.x = CesiumMath.randomBetween(
      system._minimumImageSize.x,
      system._maximumImageSize.x
    );
    particle.imageSize.y = CesiumMath.randomBetween(
      system._minimumImageSize.y,
      system._maximumImageSize.y
    );

    // Reset the normalizedAge and age in case the particle was reused.
    particle._normalizedAge = 0.0;
    particle._age = 0.0;

    var speed = CesiumMath.randomBetween(
      system._minimumSpeed,
      system._maximumSpeed
    );
    Cartesian3.multiplyByScalar(particle.velocity, speed, particle.velocity);

    system._particles.push(particle);
  }

  function calculateNumberToEmit(system, dt) {
    // This emitter is finished if it exceeds it's lifetime.
    if (system._isComplete) {
      return 0;
    }

    dt = CesiumMath.mod(dt, system._lifetime);

    // Compute the number of particles to emit based on the emissionRate.
    var v = dt * system._emissionRate;
    var numToEmit = Math.floor(v);
    system._carryOver += v - numToEmit;
    if (system._carryOver > 1.0) {
      numToEmit++;
      system._carryOver -= 1.0;
    }

    // Apply any bursts
    if (defined(system.bursts)) {
      var length = system.bursts.length;
      for (var i = 0; i < length; i++) {
        var burst = system.bursts[i];
        var currentTime = system._currentTime;
        if (defined(burst) && !burst._complete && currentTime > burst.time) {
          numToEmit += CesiumMath.randomBetween(burst.minimum, burst.maximum);
          burst._complete = true;
        }
      }
    }

    return numToEmit;
  }

  var rotatedVelocityScratch = new Cartesian3();

  /**
   * @private
   */
  ParticleSystem.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    if (!defined(this._billboardCollection)) {
      this._billboardCollection = new BillboardCollection();
    }

    if (this._updateParticlePool) {
      updateParticlePool(this);
      this._updateParticlePool = false;
    }

    // Compute the frame time
    var dt = 0.0;
    if (this._previousTime) {
      dt = JulianDate.secondsDifference(frameState.time, this._previousTime);
    }

    if (dt < 0.0) {
      dt = 0.0;
    }

    var particles = this._particles;
    var emitter = this._emitter;
    var updateCallback = this.updateCallback;

    var i;
    var particle;

    // update particles and remove dead particles
    var length = particles.length;
    for (i = 0; i < length; ++i) {
      particle = particles[i];
      if (!particle.update(dt, updateCallback)) {
        removeBillboard(particle);
        // Add the particle back to the pool so it can be reused.
        addParticleToPool(this, particle);
        particles[i] = particles[length - 1];
        --i;
        --length;
      } else {
        updateBillboard(this, particle);
      }
    }
    particles.length = length;

    var numToEmit = calculateNumberToEmit(this, dt);

    if (numToEmit > 0 && defined(emitter)) {
      // Compute the final model matrix by combining the particle systems model matrix and the emitter matrix.
      if (this._matrixDirty) {
        this._combinedMatrix = Matrix4.multiply(
          this.modelMatrix,
          this.emitterModelMatrix,
          this._combinedMatrix
        );
        this._matrixDirty = false;
      }

      var combinedMatrix = this._combinedMatrix;

      for (i = 0; i < numToEmit; i++) {
        // Create a new particle.
        particle = getOrCreateParticle(this);

        // Let the emitter initialize the particle.
        this._emitter.emit(particle);

        //For the velocity we need to add it to the original position and then multiply by point.
        Cartesian3.add(
          particle.position,
          particle.velocity,
          rotatedVelocityScratch
        );
        Matrix4.multiplyByPoint(
          combinedMatrix,
          rotatedVelocityScratch,
          rotatedVelocityScratch
        );

        // Change the position to be in world coordinates
        particle.position = Matrix4.multiplyByPoint(
          combinedMatrix,
          particle.position,
          particle.position
        );

        // Orient the velocity in world space as well.
        Cartesian3.subtract(
          rotatedVelocityScratch,
          particle.position,
          particle.velocity
        );
        Cartesian3.normalize(particle.velocity, particle.velocity);

        // Add the particle to the system.
        addParticle(this, particle);
        updateBillboard(this, particle);
      }
    }

    this._billboardCollection.update(frameState);
    this._previousTime = JulianDate.clone(frameState.time, this._previousTime);
    this._currentTime += dt;

    if (
      this._lifetime !== Number.MAX_VALUE &&
      this._currentTime > this._lifetime
    ) {
      if (this.loop) {
        this._currentTime = CesiumMath.mod(this._currentTime, this._lifetime);
        if (this.bursts) {
          var burstLength = this.bursts.length;
          // Reset any bursts
          for (i = 0; i < burstLength; i++) {
            this.bursts[i]._complete = false;
          }
        }
      } else {
        this._isComplete = true;
        this._complete.raiseEvent(this);
      }
    }

    // free particles in the pool and release billboard GPU memory
    if (frameState.frameNumber % 120 === 0) {
      freeParticlePool(this);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see ParticleSystem#destroy
   */
  ParticleSystem.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see ParticleSystem#isDestroyed
   */
  ParticleSystem.prototype.destroy = function () {
    this._billboardCollection =
      this._billboardCollection && this._billboardCollection.destroy();
    return destroyObject(this);
  };

  /**
   * If element is a string, look up the element in the DOM by ID.  Otherwise return element.
   *
   * @private
   *
   * @exception {DeveloperError} Element with id "id" does not exist in the document.
   */
  function getElement(element) {
    if (typeof element === "string") {
      var foundElement = document.getElementById(element);

      //>>includeStart('debug', pragmas.debug);
      if (foundElement === null) {
        throw new DeveloperError(
          'Element with id "' + element + '" does not exist in the document.'
        );
      }
      //>>includeEnd('debug');

      element = foundElement;
    }
    return element;
  }

  /**
   * @private
   */
  function PerformanceDisplay(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var container = getElement(options.container);
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required");
    }
    //>>includeEnd('debug');

    this._container = container;

    var display = document.createElement("div");
    display.className = "cesium-performanceDisplay";
    var fpsElement = document.createElement("div");
    fpsElement.className = "cesium-performanceDisplay-fps";
    this._fpsText = document.createTextNode("");
    fpsElement.appendChild(this._fpsText);
    var msElement = document.createElement("div");
    msElement.className = "cesium-performanceDisplay-ms";
    this._msText = document.createTextNode("");
    msElement.appendChild(this._msText);
    display.appendChild(msElement);
    display.appendChild(fpsElement);
    this._container.appendChild(display);

    this._lastFpsSampleTime = getTimestamp$1();
    this._lastMsSampleTime = getTimestamp$1();
    this._fpsFrameCount = 0;
    this._msFrameCount = 0;

    this._throttled = false;
    var throttledElement = document.createElement("div");
    throttledElement.className = "cesium-performanceDisplay-throttled";
    this._throttledText = document.createTextNode("");
    throttledElement.appendChild(this._throttledText);
    display.appendChild(throttledElement);
  }

  Object.defineProperties(PerformanceDisplay.prototype, {
    /**
     * The display should indicate the FPS is being throttled.
     * @memberof PerformanceDisplay.prototype
     *
     * @type {Boolean}
     */
    throttled: {
      get: function () {
        return this._throttled;
      },
      set: function (value) {
        if (this._throttled === value) {
          return;
        }

        if (value) {
          this._throttledText.nodeValue = "(throttled)";
        } else {
          this._throttledText.nodeValue = "";
        }

        this._throttled = value;
      },
    },
  });

  /**
   * Update the display.  This function should only be called once per frame, because
   * each call records a frame in the internal buffer and redraws the display.
   *
   * @param {Boolean} [renderedThisFrame=true] If provided, the FPS count will only update and display if true.
   */
  PerformanceDisplay.prototype.update = function (renderedThisFrame) {
    var time = getTimestamp$1();
    var updateDisplay = defaultValue(renderedThisFrame, true);

    this._fpsFrameCount++;
    var fpsElapsedTime = time - this._lastFpsSampleTime;
    if (fpsElapsedTime > 1000) {
      var fps = "N/A";
      if (updateDisplay) {
        fps = ((this._fpsFrameCount * 1000) / fpsElapsedTime) | 0;
      }

      this._fpsText.nodeValue = fps + " FPS";
      this._lastFpsSampleTime = time;
      this._fpsFrameCount = 0;
    }

    this._msFrameCount++;
    var msElapsedTime = time - this._lastMsSampleTime;
    if (msElapsedTime > 200) {
      var ms = "N/A";
      if (updateDisplay) {
        ms = (msElapsedTime / this._msFrameCount).toFixed(2);
      }

      this._msText.nodeValue = ms + " MS";
      this._lastMsSampleTime = time;
      this._msFrameCount = 0;
    }
  };

  /**
   * Destroys the WebGL resources held by this object.
   */
  PerformanceDisplay.prototype.destroy = function () {
    return destroyObject(this);
  };

  /**
   * @private
   */
  function PickDepth() {
    this._framebuffer = undefined;

    this._depthTexture = undefined;
    this._textureToCopy = undefined;
    this._copyDepthCommand = undefined;

    this._useLogDepth = undefined;

    this._debugPickDepthViewportCommand = undefined;
  }

  function executeDebugPickDepth(pickDepth, context, passState, useLogDepth) {
    if (
      !defined(pickDepth._debugPickDepthViewportCommand) ||
      useLogDepth !== pickDepth._useLogDepth
    ) {
      var fsSource =
        "uniform sampler2D u_texture;\n" +
        "varying vec2 v_textureCoordinates;\n" +
        "void main()\n" +
        "{\n" +
        "    float z_window = czm_unpackDepth(texture2D(u_texture, v_textureCoordinates));\n" +
        "    z_window = czm_reverseLogDepth(z_window); \n" +
        "    float n_range = czm_depthRange.near;\n" +
        "    float f_range = czm_depthRange.far;\n" +
        "    float z_ndc = (2.0 * z_window - n_range - f_range) / (f_range - n_range);\n" +
        "    float scale = pow(z_ndc * 0.5 + 0.5, 8.0);\n" +
        "    gl_FragColor = vec4(mix(vec3(0.0), vec3(1.0), scale), 1.0);\n" +
        "}\n";
      var fs = new ShaderSource({
        defines: [useLogDepth ? "LOG_DEPTH" : ""],
        sources: [fsSource],
      });

      pickDepth._debugPickDepthViewportCommand = context.createViewportQuadCommand(
        fs,
        {
          uniformMap: {
            u_texture: function () {
              return pickDepth._depthTexture;
            },
          },
          owner: pickDepth,
        }
      );

      pickDepth._useLogDepth = useLogDepth;
    }

    pickDepth._debugPickDepthViewportCommand.execute(context, passState);
  }

  function destroyTextures$2(pickDepth) {
    pickDepth._depthTexture =
      pickDepth._depthTexture &&
      !pickDepth._depthTexture.isDestroyed() &&
      pickDepth._depthTexture.destroy();
  }

  function destroyFramebuffers$3(pickDepth) {
    pickDepth._framebuffer =
      pickDepth._framebuffer &&
      !pickDepth._framebuffer.isDestroyed() &&
      pickDepth._framebuffer.destroy();
  }

  function createTextures$2(pickDepth, context, width, height) {
    pickDepth._depthTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
    });
  }

  function createFramebuffers$2(pickDepth, context, width, height) {
    destroyTextures$2(pickDepth);
    destroyFramebuffers$3(pickDepth);

    createTextures$2(pickDepth, context, width, height);

    pickDepth._framebuffer = new Framebuffer({
      context: context,
      colorTextures: [pickDepth._depthTexture],
      destroyAttachments: false,
    });
  }

  function updateFramebuffers$2(pickDepth, context, depthTexture) {
    var width = depthTexture.width;
    var height = depthTexture.height;

    var texture = pickDepth._depthTexture;
    var textureChanged =
      !defined(texture) || texture.width !== width || texture.height !== height;
    if (!defined(pickDepth._framebuffer) || textureChanged) {
      createFramebuffers$2(pickDepth, context, width, height);
    }
  }

  function updateCopyCommands$1(pickDepth, context, depthTexture) {
    if (!defined(pickDepth._copyDepthCommand)) {
      var fs =
        "uniform sampler2D u_texture;\n" +
        "varying vec2 v_textureCoordinates;\n" +
        "void main()\n" +
        "{\n" +
        "    gl_FragColor = czm_packDepth(texture2D(u_texture, v_textureCoordinates).r);\n" +
        "}\n";
      pickDepth._copyDepthCommand = context.createViewportQuadCommand(fs, {
        renderState: RenderState.fromCache(),
        uniformMap: {
          u_texture: function () {
            return pickDepth._textureToCopy;
          },
        },
        owner: pickDepth,
      });
    }

    pickDepth._textureToCopy = depthTexture;
    pickDepth._copyDepthCommand.framebuffer = pickDepth._framebuffer;
  }

  PickDepth.prototype.executeDebugPickDepth = function (
    context,
    passState,
    useLogDepth
  ) {
    executeDebugPickDepth(this, context, passState, useLogDepth);
  };

  PickDepth.prototype.update = function (context, depthTexture) {
    updateFramebuffers$2(this, context, depthTexture);
    updateCopyCommands$1(this, context, depthTexture);
  };

  var scratchPackedDepth = new Cartesian4();
  var packedDepthScale = new Cartesian4(
    1.0,
    1.0 / 255.0,
    1.0 / 65025.0,
    1.0 / 16581375.0
  );

  PickDepth.prototype.getDepth = function (context, x, y) {
    // If this function is called before the framebuffer is created, the depth is undefined.
    if (!defined(this._framebuffer)) {
      return undefined;
    }

    var pixels = context.readPixels({
      x: x,
      y: y,
      width: 1,
      height: 1,
      framebuffer: this._framebuffer,
    });

    var packedDepth = Cartesian4.unpack(pixels, 0, scratchPackedDepth);
    Cartesian4.divideByScalar(packedDepth, 255.0, packedDepth);
    return Cartesian4.dot(packedDepth, packedDepthScale);
  };

  PickDepth.prototype.executeCopyDepth = function (context, passState) {
    this._copyDepthCommand.execute(context, passState);
  };

  PickDepth.prototype.isDestroyed = function () {
    return false;
  };

  PickDepth.prototype.destroy = function () {
    destroyTextures$2(this);
    destroyFramebuffers$3(this);

    if (defined(this._copyDepthCommand)) {
      this._copyDepthCommand.shaderProgram =
        defined(this._copyDepthCommand.shaderProgram) &&
        this._copyDepthCommand.shaderProgram.destroy();
    }

    return destroyObject(this);
  };

  /**
   * @private
   */
  function PickDepthFramebuffer() {
    this._depthStencilTexture = undefined;
    this._framebuffer = undefined;
    this._passState = undefined;
  }

  function destroyResources$2(pickDepth) {
    pickDepth._framebuffer =
      pickDepth._framebuffer && pickDepth._framebuffer.destroy();
    pickDepth._depthStencilTexture =
      pickDepth._depthStencilTexture && pickDepth._depthStencilTexture.destroy();
  }

  function createResources$6(pickDepth, context) {
    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight;

    pickDepth._depthStencilTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.DEPTH_STENCIL,
      pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
    });

    pickDepth._framebuffer = new Framebuffer({
      context: context,
      depthStencilTexture: pickDepth._depthStencilTexture,
      destroyAttachments: false,
    });

    var passState = new PassState(context);
    passState.blendingEnabled = false;
    passState.scissorTest = {
      enabled: true,
      rectangle: new BoundingRectangle(),
    };
    passState.viewport = new BoundingRectangle();
    pickDepth._passState = passState;
  }

  PickDepthFramebuffer.prototype.update = function (
    context,
    drawingBufferPosition,
    viewport
  ) {
    var width = viewport.width;
    var height = viewport.height;

    if (
      !defined(this._framebuffer) ||
      width !== this._depthStencilTexture.width ||
      height !== this._depthStencilTexture.height
    ) {
      destroyResources$2(this);
      createResources$6(this, context);
    }

    var framebuffer = this._framebuffer;
    var passState = this._passState;
    passState.framebuffer = framebuffer;
    passState.viewport.width = width;
    passState.viewport.height = height;
    passState.scissorTest.rectangle.x = drawingBufferPosition.x;
    passState.scissorTest.rectangle.y = height - drawingBufferPosition.y;
    passState.scissorTest.rectangle.width = 1;
    passState.scissorTest.rectangle.height = 1;

    return passState;
  };

  PickDepthFramebuffer.prototype.isDestroyed = function () {
    return false;
  };

  PickDepthFramebuffer.prototype.destroy = function () {
    destroyResources$2(this);
    return destroyObject(this);
  };

  /**
   * @private
   */
  function PickFramebuffer(context) {
    // Override per-command states
    var passState = new PassState(context);
    passState.blendingEnabled = false;
    passState.scissorTest = {
      enabled: true,
      rectangle: new BoundingRectangle(),
    };
    passState.viewport = new BoundingRectangle();

    this._context = context;
    this._fb = undefined;
    this._passState = passState;
    this._width = 0;
    this._height = 0;
  }
  PickFramebuffer.prototype.begin = function (screenSpaceRectangle, viewport) {
    var context = this._context;
    var width = viewport.width;
    var height = viewport.height;

    BoundingRectangle.clone(
      screenSpaceRectangle,
      this._passState.scissorTest.rectangle
    );

    // Initially create or recreate renderbuffers and framebuffer used for picking
    if (!defined(this._fb) || this._width !== width || this._height !== height) {
      this._width = width;
      this._height = height;

      this._fb = this._fb && this._fb.destroy();
      this._fb = new Framebuffer({
        context: context,
        colorTextures: [
          new Texture({
            context: context,
            width: width,
            height: height,
          }),
        ],
        depthStencilRenderbuffer: new Renderbuffer({
          context: context,
          width: width,
          height: height,
          format: RenderbufferFormat$1.DEPTH_STENCIL,
        }),
      });
      this._passState.framebuffer = this._fb;
    }

    this._passState.viewport.width = width;
    this._passState.viewport.height = height;

    return this._passState;
  };

  var colorScratch$7 = new Color();

  PickFramebuffer.prototype.end = function (screenSpaceRectangle) {
    var width = defaultValue(screenSpaceRectangle.width, 1.0);
    var height = defaultValue(screenSpaceRectangle.height, 1.0);

    var context = this._context;
    var pixels = context.readPixels({
      x: screenSpaceRectangle.x,
      y: screenSpaceRectangle.y,
      width: width,
      height: height,
      framebuffer: this._fb,
    });

    var max = Math.max(width, height);
    var length = max * max;
    var halfWidth = Math.floor(width * 0.5);
    var halfHeight = Math.floor(height * 0.5);

    var x = 0;
    var y = 0;
    var dx = 0;
    var dy = -1;

    // Spiral around the center pixel, this is a workaround until
    // we can access the depth buffer on all browsers.

    // The region does not have to square and the dimensions do not have to be odd, but
    // loop iterations would be wasted. Prefer square regions where the size is odd.
    for (var i = 0; i < length; ++i) {
      if (
        -halfWidth <= x &&
        x <= halfWidth &&
        -halfHeight <= y &&
        y <= halfHeight
      ) {
        var index = 4 * ((halfHeight - y) * width + x + halfWidth);

        colorScratch$7.red = Color.byteToFloat(pixels[index]);
        colorScratch$7.green = Color.byteToFloat(pixels[index + 1]);
        colorScratch$7.blue = Color.byteToFloat(pixels[index + 2]);
        colorScratch$7.alpha = Color.byteToFloat(pixels[index + 3]);

        var object = context.getObjectByPickColor(colorScratch$7);
        if (defined(object)) {
          return object;
        }
      }

      // if (top right || bottom left corners) || (top left corner) || (bottom right corner + (1, 0))
      // change spiral direction
      if (x === y || (x < 0 && -x === y) || (x > 0 && x === 1 - y)) {
        var temp = dx;
        dx = -dy;
        dy = temp;
      }

      x += dx;
      y += dy;
    }

    return undefined;
  };

  PickFramebuffer.prototype.isDestroyed = function () {
    return false;
  };

  PickFramebuffer.prototype.destroy = function () {
    this._fb = this._fb && this._fb.destroy();
    return destroyObject(this);
  };

  /**
   * @private
   */
  function SceneFramebuffer() {
    this._colorTexture = undefined;
    this._idTexture = undefined;
    this._depthStencilTexture = undefined;
    this._depthStencilRenderbuffer = undefined;
    this._framebuffer = undefined;
    this._idFramebuffer = undefined;

    this._idClearColor = new Color(0.0, 0.0, 0.0, 0.0);

    this._useHdr = undefined;

    this._clearCommand = new ClearCommand({
      color: new Color(0.0, 0.0, 0.0, 0.0),
      depth: 1.0,
      owner: this,
    });
  }

  function destroyResources$3(post) {
    post._framebuffer = post._framebuffer && post._framebuffer.destroy();
    post._idFramebuffer = post._idFramebuffer && post._idFramebuffer.destroy();
    post._colorTexture = post._colorTexture && post._colorTexture.destroy();
    post._idTexture = post._idTexture && post._idTexture.destroy();
    post._depthStencilTexture =
      post._depthStencilTexture && post._depthStencilTexture.destroy();
    post._depthStencilRenderbuffer =
      post._depthStencilRenderbuffer && post._depthStencilRenderbuffer.destroy();
    post._depthStencilIdTexture =
      post._depthStencilIdTexture && post._depthStencilIdTexture.destroy();
    post._depthStencilIdRenderbuffer =
      post._depthStencilIdRenderbuffer &&
      post._depthStencilIdRenderbuffer.destroy();

    post._framebuffer = undefined;
    post._idFramebuffer = undefined;
    post._colorTexture = undefined;
    post._idTexture = undefined;
    post._depthStencilTexture = undefined;
    post._depthStencilRenderbuffer = undefined;
    post._depthStencilIdTexture = undefined;
    post._depthStencilIdRenderbuffer = undefined;
  }

  SceneFramebuffer.prototype.update = function (context, viewport, hdr) {
    var width = viewport.width;
    var height = viewport.height;
    var colorTexture = this._colorTexture;
    if (
      defined(colorTexture) &&
      colorTexture.width === width &&
      colorTexture.height === height &&
      hdr === this._useHdr
    ) {
      return;
    }

    destroyResources$3(this);
    this._useHdr = hdr;

    var pixelDatatype = hdr
      ? context.halfFloatingPointTexture
        ? PixelDatatype$1.HALF_FLOAT
        : PixelDatatype$1.FLOAT
      : PixelDatatype$1.UNSIGNED_BYTE;
    this._colorTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: pixelDatatype,
      sampler: Sampler.NEAREST,
    });

    this._idTexture = new Texture({
      context: context,
      width: width,
      height: height,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    if (context.depthTexture) {
      this._depthStencilTexture = new Texture({
        context: context,
        width: width,
        height: height,
        pixelFormat: PixelFormat$1.DEPTH_STENCIL,
        pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
        sampler: Sampler.NEAREST,
      });
      this._depthStencilIdTexture = new Texture({
        context: context,
        width: width,
        height: height,
        pixelFormat: PixelFormat$1.DEPTH_STENCIL,
        pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
        sampler: Sampler.NEAREST,
      });
    } else {
      this._depthStencilRenderbuffer = new Renderbuffer({
        context: context,
        width: width,
        height: height,
        format: RenderbufferFormat$1.DEPTH_STENCIL,
      });
      this._depthStencilIdRenderbuffer = new Renderbuffer({
        context: context,
        width: width,
        height: height,
        format: RenderbufferFormat$1.DEPTH_STENCIL,
      });
    }

    this._framebuffer = new Framebuffer({
      context: context,
      colorTextures: [this._colorTexture],
      depthStencilTexture: this._depthStencilTexture,
      depthStencilRenderbuffer: this._depthStencilRenderbuffer,
      destroyAttachments: false,
    });

    this._idFramebuffer = new Framebuffer({
      context: context,
      colorTextures: [this._idTexture],
      depthStencilTexture: this._depthStencilIdTexture,
      depthStencilRenderbuffer: this._depthStencilIdRenderbuffer,
      destroyAttachments: false,
    });
  };

  SceneFramebuffer.prototype.clear = function (context, passState, clearColor) {
    var framebuffer = passState.framebuffer;

    passState.framebuffer = this._framebuffer;
    Color.clone(clearColor, this._clearCommand.color);
    this._clearCommand.execute(context, passState);

    passState.framebuffer = this._idFramebuffer;
    Color.clone(this._idClearColor, this._clearCommand.color);
    this._clearCommand.execute(context, passState);

    passState.framebuffer = framebuffer;
  };

  SceneFramebuffer.prototype.getFramebuffer = function () {
    return this._framebuffer;
  };

  SceneFramebuffer.prototype.getIdFramebuffer = function () {
    return this._idFramebuffer;
  };

  SceneFramebuffer.prototype.isDestroyed = function () {
    return false;
  };

  SceneFramebuffer.prototype.destroy = function () {
    destroyResources$3(this);
    return destroyObject(this);
  };

  /**
   * @private
   */
  function ShadowMapShader() {}

  ShadowMapShader.getShadowCastShaderKeyword = function (
    isPointLight,
    isTerrain,
    usesDepthTexture,
    isOpaque
  ) {
    return (
      "castShadow " +
      isPointLight +
      " " +
      isTerrain +
      " " +
      usesDepthTexture +
      " " +
      isOpaque
    );
  };

  ShadowMapShader.createShadowCastVertexShader = function (
    vs,
    isPointLight,
    isTerrain
  ) {
    var defines = vs.defines.slice(0);
    var sources = vs.sources.slice(0);

    defines.push("SHADOW_MAP");

    if (isTerrain) {
      defines.push("GENERATE_POSITION");
    }

    var positionVaryingName = ShaderSource.findPositionVarying(vs);
    var hasPositionVarying = defined(positionVaryingName);

    if (isPointLight && !hasPositionVarying) {
      var length = sources.length;
      for (var j = 0; j < length; ++j) {
        sources[j] = ShaderSource.replaceMain(sources[j], "czm_shadow_cast_main");
      }

      var shadowVS =
        "varying vec3 v_positionEC; \n" +
        "void main() \n" +
        "{ \n" +
        "    czm_shadow_cast_main(); \n" +
        "    v_positionEC = (czm_inverseProjection * gl_Position).xyz; \n" +
        "}";
      sources.push(shadowVS);
    }

    return new ShaderSource({
      defines: defines,
      sources: sources,
    });
  };

  ShadowMapShader.createShadowCastFragmentShader = function (
    fs,
    isPointLight,
    usesDepthTexture,
    opaque
  ) {
    var defines = fs.defines.slice(0);
    var sources = fs.sources.slice(0);

    var positionVaryingName = ShaderSource.findPositionVarying(fs);
    var hasPositionVarying = defined(positionVaryingName);
    if (!hasPositionVarying) {
      positionVaryingName = "v_positionEC";
    }

    var length = sources.length;
    for (var i = 0; i < length; ++i) {
      sources[i] = ShaderSource.replaceMain(sources[i], "czm_shadow_cast_main");
    }

    var fsSource = "";

    if (isPointLight) {
      if (!hasPositionVarying) {
        fsSource += "varying vec3 v_positionEC; \n";
      }
      fsSource += "uniform vec4 shadowMap_lightPositionEC; \n";
    }

    if (opaque) {
      fsSource += "void main() \n" + "{ \n";
    } else {
      fsSource +=
        "void main() \n" +
        "{ \n" +
        "    czm_shadow_cast_main(); \n" +
        "    if (gl_FragColor.a == 0.0) \n" +
        "    { \n" +
        "       discard; \n" +
        "    } \n";
    }

    if (isPointLight) {
      fsSource +=
        "    float distance = length(" +
        positionVaryingName +
        "); \n" +
        "    if (distance >= shadowMap_lightPositionEC.w) \n" +
        "    { \n" +
        "        discard; \n" +
        "    } \n" +
        "    distance /= shadowMap_lightPositionEC.w; // radius \n" +
        "    gl_FragColor = czm_packDepth(distance); \n";
    } else if (usesDepthTexture) {
      fsSource += "    gl_FragColor = vec4(1.0); \n";
    } else {
      fsSource += "    gl_FragColor = czm_packDepth(gl_FragCoord.z); \n";
    }

    fsSource += "} \n";

    sources.push(fsSource);

    return new ShaderSource({
      defines: defines,
      sources: sources,
    });
  };

  ShadowMapShader.getShadowReceiveShaderKeyword = function (
    shadowMap,
    castShadows,
    isTerrain,
    hasTerrainNormal
  ) {
    var usesDepthTexture = shadowMap._usesDepthTexture;
    var polygonOffsetSupported = shadowMap._polygonOffsetSupported;
    var isPointLight = shadowMap._isPointLight;
    var isSpotLight = shadowMap._isSpotLight;
    var hasCascades = shadowMap._numberOfCascades > 1;
    var debugCascadeColors = shadowMap.debugCascadeColors;
    var softShadows = shadowMap.softShadows;

    return (
      "receiveShadow " +
      usesDepthTexture +
      polygonOffsetSupported +
      isPointLight +
      isSpotLight +
      hasCascades +
      debugCascadeColors +
      softShadows +
      castShadows +
      isTerrain +
      hasTerrainNormal
    );
  };

  ShadowMapShader.createShadowReceiveVertexShader = function (
    vs,
    isTerrain,
    hasTerrainNormal
  ) {
    var defines = vs.defines.slice(0);
    var sources = vs.sources.slice(0);

    defines.push("SHADOW_MAP");

    if (isTerrain) {
      if (hasTerrainNormal) {
        defines.push("GENERATE_POSITION_AND_NORMAL");
      } else {
        defines.push("GENERATE_POSITION");
      }
    }

    return new ShaderSource({
      defines: defines,
      sources: sources,
    });
  };

  ShadowMapShader.createShadowReceiveFragmentShader = function (
    fs,
    shadowMap,
    castShadows,
    isTerrain,
    hasTerrainNormal
  ) {
    var normalVaryingName = ShaderSource.findNormalVarying(fs);
    var hasNormalVarying =
      (!isTerrain && defined(normalVaryingName)) ||
      (isTerrain && hasTerrainNormal);

    var positionVaryingName = ShaderSource.findPositionVarying(fs);
    var hasPositionVarying = defined(positionVaryingName);

    var usesDepthTexture = shadowMap._usesDepthTexture;
    var polygonOffsetSupported = shadowMap._polygonOffsetSupported;
    var isPointLight = shadowMap._isPointLight;
    var isSpotLight = shadowMap._isSpotLight;
    var hasCascades = shadowMap._numberOfCascades > 1;
    var debugCascadeColors = shadowMap.debugCascadeColors;
    var softShadows = shadowMap.softShadows;
    var bias = isPointLight
      ? shadowMap._pointBias
      : isTerrain
      ? shadowMap._terrainBias
      : shadowMap._primitiveBias;

    var defines = fs.defines.slice(0);
    var sources = fs.sources.slice(0);

    var length = sources.length;
    for (var i = 0; i < length; ++i) {
      sources[i] = ShaderSource.replaceMain(
        sources[i],
        "czm_shadow_receive_main"
      );
    }

    if (isPointLight) {
      defines.push("USE_CUBE_MAP_SHADOW");
    } else if (usesDepthTexture) {
      defines.push("USE_SHADOW_DEPTH_TEXTURE");
    }

    if (softShadows && !isPointLight) {
      defines.push("USE_SOFT_SHADOWS");
    }

    // Enable day-night shading so that the globe is dark when the light is below the horizon
    if (hasCascades && castShadows && isTerrain) {
      if (hasNormalVarying) {
        defines.push("ENABLE_VERTEX_LIGHTING");
      } else {
        defines.push("ENABLE_DAYNIGHT_SHADING");
      }
    }

    if (castShadows && bias.normalShading && hasNormalVarying) {
      defines.push("USE_NORMAL_SHADING");
      if (bias.normalShadingSmooth > 0.0) {
        defines.push("USE_NORMAL_SHADING_SMOOTH");
      }
    }

    var fsSource = "";

    if (isPointLight) {
      fsSource += "uniform samplerCube shadowMap_textureCube; \n";
    } else {
      fsSource += "uniform sampler2D shadowMap_texture; \n";
    }

    var returnPositionEC;
    if (hasPositionVarying) {
      returnPositionEC = "    return vec4(" + positionVaryingName + ", 1.0); \n";
    } else {
      returnPositionEC =
        "#ifndef LOG_DEPTH \n" +
        "    return czm_windowToEyeCoordinates(gl_FragCoord); \n" +
        "#else \n" +
        "    return vec4(v_logPositionEC, 1.0); \n" +
        "#endif \n";
    }

    fsSource +=
      "uniform mat4 shadowMap_matrix; \n" +
      "uniform vec3 shadowMap_lightDirectionEC; \n" +
      "uniform vec4 shadowMap_lightPositionEC; \n" +
      "uniform vec4 shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness; \n" +
      "uniform vec4 shadowMap_texelSizeDepthBiasAndNormalShadingSmooth; \n" +
      "#ifdef LOG_DEPTH \n" +
      "varying vec3 v_logPositionEC; \n" +
      "#endif \n" +
      "vec4 getPositionEC() \n" +
      "{ \n" +
      returnPositionEC +
      "} \n" +
      "vec3 getNormalEC() \n" +
      "{ \n" +
      (hasNormalVarying
        ? "    return normalize(" + normalVaryingName + "); \n"
        : "    return vec3(1.0); \n") +
      "} \n" +
      // Offset the shadow position in the direction of the normal for perpendicular and back faces
      "void applyNormalOffset(inout vec4 positionEC, vec3 normalEC, float nDotL) \n" +
      "{ \n" +
      (bias.normalOffset && hasNormalVarying
        ? "    float normalOffset = shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness.x; \n" +
          "    float normalOffsetScale = 1.0 - nDotL; \n" +
          "    vec3 offset = normalOffset * normalOffsetScale * normalEC; \n" +
          "    positionEC.xyz += offset; \n"
        : "") +
      "} \n";

    fsSource +=
      "void main() \n" +
      "{ \n" +
      "    czm_shadow_receive_main(); \n" +
      "    vec4 positionEC = getPositionEC(); \n" +
      "    vec3 normalEC = getNormalEC(); \n" +
      "    float depth = -positionEC.z; \n";

    fsSource +=
      "    czm_shadowParameters shadowParameters; \n" +
      "    shadowParameters.texelStepSize = shadowMap_texelSizeDepthBiasAndNormalShadingSmooth.xy; \n" +
      "    shadowParameters.depthBias = shadowMap_texelSizeDepthBiasAndNormalShadingSmooth.z; \n" +
      "    shadowParameters.normalShadingSmooth = shadowMap_texelSizeDepthBiasAndNormalShadingSmooth.w; \n" +
      "    shadowParameters.darkness = shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness.w; \n";

    if (isTerrain) {
      // Scale depth bias based on view distance to reduce z-fighting in distant terrain
      fsSource += "    shadowParameters.depthBias *= max(depth * 0.01, 1.0); \n";
    } else if (!polygonOffsetSupported) {
      // If polygon offset isn't supported push the depth back based on view, however this
      // causes light leaking at further away views
      fsSource +=
        "    shadowParameters.depthBias *= mix(1.0, 100.0, depth * 0.0015); \n";
    }

    if (isPointLight) {
      fsSource +=
        "    vec3 directionEC = positionEC.xyz - shadowMap_lightPositionEC.xyz; \n" +
        "    float distance = length(directionEC); \n" +
        "    directionEC = normalize(directionEC); \n" +
        "    float radius = shadowMap_lightPositionEC.w; \n" +
        "    // Stop early if the fragment is beyond the point light radius \n" +
        "    if (distance > radius) \n" +
        "    { \n" +
        "        return; \n" +
        "    } \n" +
        "    vec3 directionWC  = czm_inverseViewRotation * directionEC; \n" +
        "    shadowParameters.depth = distance / radius; \n" +
        "    shadowParameters.nDotL = clamp(dot(normalEC, -directionEC), 0.0, 1.0); \n" +
        "    shadowParameters.texCoords = directionWC; \n" +
        "    float visibility = czm_shadowVisibility(shadowMap_textureCube, shadowParameters); \n";
    } else if (isSpotLight) {
      fsSource +=
        "    vec3 directionEC = normalize(positionEC.xyz - shadowMap_lightPositionEC.xyz); \n" +
        "    float nDotL = clamp(dot(normalEC, -directionEC), 0.0, 1.0); \n" +
        "    applyNormalOffset(positionEC, normalEC, nDotL); \n" +
        "    vec4 shadowPosition = shadowMap_matrix * positionEC; \n" +
        "    // Spot light uses a perspective projection, so perform the perspective divide \n" +
        "    shadowPosition /= shadowPosition.w; \n" +
        "    // Stop early if the fragment is not in the shadow bounds \n" +
        "    if (any(lessThan(shadowPosition.xyz, vec3(0.0))) || any(greaterThan(shadowPosition.xyz, vec3(1.0)))) \n" +
        "    { \n" +
        "        return; \n" +
        "    } \n" +
        "    shadowParameters.texCoords = shadowPosition.xy; \n" +
        "    shadowParameters.depth = shadowPosition.z; \n" +
        "    shadowParameters.nDotL = nDotL; \n" +
        "    float visibility = czm_shadowVisibility(shadowMap_texture, shadowParameters); \n";
    } else if (hasCascades) {
      fsSource +=
        "    float maxDepth = shadowMap_cascadeSplits[1].w; \n" +
        "    // Stop early if the eye depth exceeds the last cascade \n" +
        "    if (depth > maxDepth) \n" +
        "    { \n" +
        "        return; \n" +
        "    } \n" +
        "    // Get the cascade based on the eye-space depth \n" +
        "    vec4 weights = czm_cascadeWeights(depth); \n" +
        "    // Apply normal offset \n" +
        "    float nDotL = clamp(dot(normalEC, shadowMap_lightDirectionEC), 0.0, 1.0); \n" +
        "    applyNormalOffset(positionEC, normalEC, nDotL); \n" +
        "    // Transform position into the cascade \n" +
        "    vec4 shadowPosition = czm_cascadeMatrix(weights) * positionEC; \n" +
        "    // Get visibility \n" +
        "    shadowParameters.texCoords = shadowPosition.xy; \n" +
        "    shadowParameters.depth = shadowPosition.z; \n" +
        "    shadowParameters.nDotL = nDotL; \n" +
        "    float visibility = czm_shadowVisibility(shadowMap_texture, shadowParameters); \n" +
        "    // Fade out shadows that are far away \n" +
        "    float shadowMapMaximumDistance = shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness.z; \n" +
        "    float fade = max((depth - shadowMapMaximumDistance * 0.8) / (shadowMapMaximumDistance * 0.2), 0.0); \n" +
        "    visibility = mix(visibility, 1.0, fade); \n" +
        (debugCascadeColors
          ? "    // Draw cascade colors for debugging \n" +
            "    gl_FragColor *= czm_cascadeColor(weights); \n"
          : "");
    } else {
      fsSource +=
        "    float nDotL = clamp(dot(normalEC, shadowMap_lightDirectionEC), 0.0, 1.0); \n" +
        "    applyNormalOffset(positionEC, normalEC, nDotL); \n" +
        "    vec4 shadowPosition = shadowMap_matrix * positionEC; \n" +
        "    // Stop early if the fragment is not in the shadow bounds \n" +
        "    if (any(lessThan(shadowPosition.xyz, vec3(0.0))) || any(greaterThan(shadowPosition.xyz, vec3(1.0)))) \n" +
        "    { \n" +
        "        return; \n" +
        "    } \n" +
        "    shadowParameters.texCoords = shadowPosition.xy; \n" +
        "    shadowParameters.depth = shadowPosition.z; \n" +
        "    shadowParameters.nDotL = nDotL; \n" +
        "    float visibility = czm_shadowVisibility(shadowMap_texture, shadowParameters); \n";
    }

    fsSource += "    gl_FragColor.rgb *= visibility; \n" + "} \n";

    sources.push(fsSource);

    return new ShaderSource({
      defines: defines,
      sources: sources,
    });
  };

  /**
   * Use {@link Viewer#shadowMap} to get the scene's shadow map. Do not construct this directly.
   *
   * <p>
   * The normalOffset bias pushes the shadows forward slightly, and may be disabled
   * for applications that require ultra precise shadows.
   * </p>
   *
   * @alias ShadowMap
   * @internalConstructor
   * @class
   *
   * @param {Object} options An object containing the following properties:
   * @param {Camera} options.lightCamera A camera representing the light source.
   * @param {Boolean} [options.enabled=true] Whether the shadow map is enabled.
   * @param {Boolean} [options.isPointLight=false] Whether the light source is a point light. Point light shadows do not use cascades.
   * @param {Boolean} [options.pointLightRadius=100.0] Radius of the point light.
   * @param {Boolean} [options.cascadesEnabled=true] Use multiple shadow maps to cover different partitions of the view frustum.
   * @param {Number} [options.numberOfCascades=4] The number of cascades to use for the shadow map. Supported values are one and four.
   * @param {Number} [options.maximumDistance=5000.0] The maximum distance used for generating cascaded shadows. Lower values improve shadow quality.
   * @param {Number} [options.size=2048] The width and height, in pixels, of each shadow map.
   * @param {Boolean} [options.softShadows=false] Whether percentage-closer-filtering is enabled for producing softer shadows.
   * @param {Number} [options.darkness=0.3] The shadow darkness.
   * @param {Boolean} [options.normalOffset=true] Whether a normal bias is applied to shadows.
   *
   * @exception {DeveloperError} Only one or four cascades are supported.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Shadows.html|Cesium Sandcastle Shadows Demo}
   */
  function ShadowMap(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    // options.context is an undocumented option
    var context = options.context;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(context)) {
      throw new DeveloperError("context is required.");
    }
    if (!defined(options.lightCamera)) {
      throw new DeveloperError("lightCamera is required.");
    }
    if (
      defined(options.numberOfCascades) &&
      options.numberOfCascades !== 1 &&
      options.numberOfCascades !== 4
    ) {
      throw new DeveloperError("Only one or four cascades are supported.");
    }
    //>>includeEnd('debug');

    this._enabled = defaultValue(options.enabled, true);
    this._softShadows = defaultValue(options.softShadows, false);
    this._normalOffset = defaultValue(options.normalOffset, true);
    this.dirty = true;

    /**
     * Specifies whether the shadow map originates from a light source. Shadow maps that are used for analytical
     * purposes should set this to false so as not to affect scene rendering.
     *
     * @private
     */
    this.fromLightSource = defaultValue(options.fromLightSource, true);

    /**
     * Determines the darkness of the shadows.
     *
     * @type {Number}
     * @default 0.3
     */
    this.darkness = defaultValue(options.darkness, 0.3);
    this._darkness = this.darkness;

    /**
     * Determines the maximum distance of the shadow map. Only applicable for cascaded shadows. Larger distances may result in lower quality shadows.
     *
     * @type {Number}
     * @default 5000.0
     */
    this.maximumDistance = defaultValue(options.maximumDistance, 5000.0);

    this._outOfView = false;
    this._outOfViewPrevious = false;
    this._needsUpdate = true;

    // In IE11 and Edge polygon offset is not functional.
    // TODO : Also disabled for instances of Firefox and Chrome running ANGLE that do not support depth textures.
    // Re-enable once https://github.com/CesiumGS/cesium/issues/4560 is resolved.
    var polygonOffsetSupported = true;
    if (
      FeatureDetection.isInternetExplorer() ||
      FeatureDetection.isEdge() ||
      ((FeatureDetection.isChrome() || FeatureDetection.isFirefox()) &&
        FeatureDetection.isWindows() &&
        !context.depthTexture)
    ) {
      polygonOffsetSupported = false;
    }
    this._polygonOffsetSupported = polygonOffsetSupported;

    this._terrainBias = {
      polygonOffset: polygonOffsetSupported,
      polygonOffsetFactor: 1.1,
      polygonOffsetUnits: 4.0,
      normalOffset: this._normalOffset,
      normalOffsetScale: 0.5,
      normalShading: true,
      normalShadingSmooth: 0.3,
      depthBias: 0.0001,
    };

    this._primitiveBias = {
      polygonOffset: polygonOffsetSupported,
      polygonOffsetFactor: 1.1,
      polygonOffsetUnits: 4.0,
      normalOffset: this._normalOffset,
      normalOffsetScale: 0.1,
      normalShading: true,
      normalShadingSmooth: 0.05,
      depthBias: 0.00002,
    };

    this._pointBias = {
      polygonOffset: false,
      polygonOffsetFactor: 1.1,
      polygonOffsetUnits: 4.0,
      normalOffset: this._normalOffset,
      normalOffsetScale: 0.0,
      normalShading: true,
      normalShadingSmooth: 0.1,
      depthBias: 0.0005,
    };

    // Framebuffer resources
    this._depthAttachment = undefined;
    this._colorAttachment = undefined;

    // Uniforms
    this._shadowMapMatrix = new Matrix4();
    this._shadowMapTexture = undefined;
    this._lightDirectionEC = new Cartesian3();
    this._lightPositionEC = new Cartesian4();
    this._distance = 0.0;

    this._lightCamera = options.lightCamera;
    this._shadowMapCamera = new ShadowMapCamera();
    this._shadowMapCullingVolume = undefined;
    this._sceneCamera = undefined;
    this._boundingSphere = new BoundingSphere();

    this._isPointLight = defaultValue(options.isPointLight, false);
    this._pointLightRadius = defaultValue(options.pointLightRadius, 100.0);

    this._cascadesEnabled = this._isPointLight
      ? false
      : defaultValue(options.cascadesEnabled, true);
    this._numberOfCascades = !this._cascadesEnabled
      ? 0
      : defaultValue(options.numberOfCascades, 4);
    this._fitNearFar = true;
    this._maximumCascadeDistances = [25.0, 150.0, 700.0, Number.MAX_VALUE];

    this._textureSize = new Cartesian2();

    this._isSpotLight = false;
    if (this._cascadesEnabled) {
      // Cascaded shadows are always orthographic. The frustum dimensions are calculated on the fly.
      this._shadowMapCamera.frustum = new OrthographicOffCenterFrustum();
    } else if (defined(this._lightCamera.frustum.fov)) {
      // If the light camera uses a perspective frustum, then the light source is a spot light
      this._isSpotLight = true;
    }

    // Uniforms
    this._cascadeSplits = [new Cartesian4(), new Cartesian4()];
    this._cascadeMatrices = [
      new Matrix4(),
      new Matrix4(),
      new Matrix4(),
      new Matrix4(),
    ];
    this._cascadeDistances = new Cartesian4();

    var numberOfPasses;
    if (this._isPointLight) {
      numberOfPasses = 6; // One shadow map for each direction
    } else if (!this._cascadesEnabled) {
      numberOfPasses = 1;
    } else {
      numberOfPasses = this._numberOfCascades;
    }

    this._passes = new Array(numberOfPasses);
    for (var i = 0; i < numberOfPasses; ++i) {
      this._passes[i] = new ShadowPass(context);
    }

    this.debugShow = false;
    this.debugFreezeFrame = false;
    this._debugFreezeFrame = false;
    this._debugCascadeColors = false;
    this._debugLightFrustum = undefined;
    this._debugCameraFrustum = undefined;
    this._debugCascadeFrustums = new Array(this._numberOfCascades);
    this._debugShadowViewCommand = undefined;

    this._usesDepthTexture = context.depthTexture;

    if (this._isPointLight) {
      this._usesDepthTexture = false;
    }

    // Create render states for shadow casters
    this._primitiveRenderState = undefined;
    this._terrainRenderState = undefined;
    this._pointRenderState = undefined;
    createRenderStates$5(this);

    // For clearing the shadow map texture every frame
    this._clearCommand = new ClearCommand({
      depth: 1.0,
      color: new Color(),
    });

    this._clearPassState = new PassState(context);

    this._size = defaultValue(options.size, 2048);
    this.size = this._size;
  }

  /**
   * Global maximum shadow distance used to prevent far off receivers from extending
   * the shadow far plane. This helps set a tighter near/far when viewing objects from space.
   *
   * @private
   */
  ShadowMap.MAXIMUM_DISTANCE = 20000.0;

  function ShadowPass(context) {
    this.camera = new ShadowMapCamera();
    this.passState = new PassState(context);
    this.framebuffer = undefined;
    this.textureOffsets = undefined;
    this.commandList = [];
    this.cullingVolume = undefined;
  }

  function createRenderState$1(colorMask, bias) {
    return RenderState.fromCache({
      cull: {
        enabled: true,
        face: CullFace$1.BACK,
      },
      depthTest: {
        enabled: true,
      },
      colorMask: {
        red: colorMask,
        green: colorMask,
        blue: colorMask,
        alpha: colorMask,
      },
      depthMask: true,
      polygonOffset: {
        enabled: bias.polygonOffset,
        factor: bias.polygonOffsetFactor,
        units: bias.polygonOffsetUnits,
      },
    });
  }

  function createRenderStates$5(shadowMap) {
    // Enable the color mask if the shadow map is backed by a color texture, e.g. when depth textures aren't supported
    var colorMask = !shadowMap._usesDepthTexture;
    shadowMap._primitiveRenderState = createRenderState$1(
      colorMask,
      shadowMap._primitiveBias
    );
    shadowMap._terrainRenderState = createRenderState$1(
      colorMask,
      shadowMap._terrainBias
    );
    shadowMap._pointRenderState = createRenderState$1(
      colorMask,
      shadowMap._pointBias
    );
  }

  /**
   * @private
   */
  ShadowMap.prototype.debugCreateRenderStates = function () {
    createRenderStates$5(this);
  };

  Object.defineProperties(ShadowMap.prototype, {
    /**
     * Determines if the shadow map will be shown.
     *
     * @memberof ShadowMap.prototype
     * @type {Boolean}
     * @default true
     */
    enabled: {
      get: function () {
        return this._enabled;
      },
      set: function (value) {
        this.dirty = this._enabled !== value;
        this._enabled = value;
      },
    },

    /**
     * Determines if a normal bias will be applied to shadows.
     *
     * @memberof ShadowMap.prototype
     * @type {Boolean}
     * @default true
     */
    normalOffset: {
      get: function () {
        return this._normalOffset;
      },
      set: function (value) {
        this.dirty = this._normalOffset !== value;
        this._normalOffset = value;
        this._terrainBias.normalOffset = value;
        this._primitiveBias.normalOffset = value;
        this._pointBias.normalOffset = value;
      },
    },

    /**
     * Determines if soft shadows are enabled. Uses pcf filtering which requires more texture reads and may hurt performance.
     *
     * @memberof ShadowMap.prototype
     * @type {Boolean}
     * @default false
     */
    softShadows: {
      get: function () {
        return this._softShadows;
      },
      set: function (value) {
        this.dirty = this._softShadows !== value;
        this._softShadows = value;
      },
    },

    /**
     * The width and height, in pixels, of each shadow map.
     *
     * @memberof ShadowMap.prototype
     * @type {Number}
     * @default 2048
     */
    size: {
      get: function () {
        return this._size;
      },
      set: function (value) {
        resize(this, value);
      },
    },

    /**
     * Whether the shadow map is out of view of the scene camera.
     *
     * @memberof ShadowMap.prototype
     * @type {Boolean}
     * @readonly
     * @private
     */
    outOfView: {
      get: function () {
        return this._outOfView;
      },
    },

    /**
     * The culling volume of the shadow frustum.
     *
     * @memberof ShadowMap.prototype
     * @type {CullingVolume}
     * @readonly
     * @private
     */
    shadowMapCullingVolume: {
      get: function () {
        return this._shadowMapCullingVolume;
      },
    },

    /**
     * The passes used for rendering shadows. Each face of a point light or each cascade for a cascaded shadow map is a separate pass.
     *
     * @memberof ShadowMap.prototype
     * @type {ShadowPass[]}
     * @readonly
     * @private
     */
    passes: {
      get: function () {
        return this._passes;
      },
    },

    /**
     * Whether the light source is a point light.
     *
     * @memberof ShadowMap.prototype
     * @type {Boolean}
     * @readonly
     * @private
     */
    isPointLight: {
      get: function () {
        return this._isPointLight;
      },
    },

    /**
     * Debug option for visualizing the cascades by color.
     *
     * @memberof ShadowMap.prototype
     * @type {Boolean}
     * @default false
     * @private
     */
    debugCascadeColors: {
      get: function () {
        return this._debugCascadeColors;
      },
      set: function (value) {
        this.dirty = this._debugCascadeColors !== value;
        this._debugCascadeColors = value;
      },
    },
  });

  function destroyFramebuffer$1(shadowMap) {
    var length = shadowMap._passes.length;
    for (var i = 0; i < length; ++i) {
      var pass = shadowMap._passes[i];
      var framebuffer = pass.framebuffer;
      if (defined(framebuffer) && !framebuffer.isDestroyed()) {
        framebuffer.destroy();
      }
      pass.framebuffer = undefined;
    }

    // Destroy the framebuffer attachments
    shadowMap._depthAttachment =
      shadowMap._depthAttachment && shadowMap._depthAttachment.destroy();
    shadowMap._colorAttachment =
      shadowMap._colorAttachment && shadowMap._colorAttachment.destroy();
  }

  function createFramebufferColor(shadowMap, context) {
    var depthRenderbuffer = new Renderbuffer({
      context: context,
      width: shadowMap._textureSize.x,
      height: shadowMap._textureSize.y,
      format: RenderbufferFormat$1.DEPTH_COMPONENT16,
    });

    var colorTexture = new Texture({
      context: context,
      width: shadowMap._textureSize.x,
      height: shadowMap._textureSize.y,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    var framebuffer = new Framebuffer({
      context: context,
      depthRenderbuffer: depthRenderbuffer,
      colorTextures: [colorTexture],
      destroyAttachments: false,
    });

    var length = shadowMap._passes.length;
    for (var i = 0; i < length; ++i) {
      var pass = shadowMap._passes[i];
      pass.framebuffer = framebuffer;
      pass.passState.framebuffer = framebuffer;
    }

    shadowMap._shadowMapTexture = colorTexture;
    shadowMap._depthAttachment = depthRenderbuffer;
    shadowMap._colorAttachment = colorTexture;
  }

  function createFramebufferDepth(shadowMap, context) {
    var depthStencilTexture = new Texture({
      context: context,
      width: shadowMap._textureSize.x,
      height: shadowMap._textureSize.y,
      pixelFormat: PixelFormat$1.DEPTH_STENCIL,
      pixelDatatype: PixelDatatype$1.UNSIGNED_INT_24_8,
      sampler: Sampler.NEAREST,
    });

    var framebuffer = new Framebuffer({
      context: context,
      depthStencilTexture: depthStencilTexture,
      destroyAttachments: false,
    });

    var length = shadowMap._passes.length;
    for (var i = 0; i < length; ++i) {
      var pass = shadowMap._passes[i];
      pass.framebuffer = framebuffer;
      pass.passState.framebuffer = framebuffer;
    }

    shadowMap._shadowMapTexture = depthStencilTexture;
    shadowMap._depthAttachment = depthStencilTexture;
  }

  function createFramebufferCube(shadowMap, context) {
    var depthRenderbuffer = new Renderbuffer({
      context: context,
      width: shadowMap._textureSize.x,
      height: shadowMap._textureSize.y,
      format: RenderbufferFormat$1.DEPTH_COMPONENT16,
    });

    var cubeMap = new CubeMap({
      context: context,
      width: shadowMap._textureSize.x,
      height: shadowMap._textureSize.y,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      sampler: Sampler.NEAREST,
    });

    var faces = [
      cubeMap.negativeX,
      cubeMap.negativeY,
      cubeMap.negativeZ,
      cubeMap.positiveX,
      cubeMap.positiveY,
      cubeMap.positiveZ,
    ];

    for (var i = 0; i < 6; ++i) {
      var framebuffer = new Framebuffer({
        context: context,
        depthRenderbuffer: depthRenderbuffer,
        colorTextures: [faces[i]],
        destroyAttachments: false,
      });
      var pass = shadowMap._passes[i];
      pass.framebuffer = framebuffer;
      pass.passState.framebuffer = framebuffer;
    }

    shadowMap._shadowMapTexture = cubeMap;
    shadowMap._depthAttachment = depthRenderbuffer;
    shadowMap._colorAttachment = cubeMap;
  }

  function createFramebuffer$3(shadowMap, context) {
    if (shadowMap._isPointLight) {
      createFramebufferCube(shadowMap, context);
    } else if (shadowMap._usesDepthTexture) {
      createFramebufferDepth(shadowMap, context);
    } else {
      createFramebufferColor(shadowMap, context);
    }
  }

  function checkFramebuffer(shadowMap, context) {
    // Attempt to make an FBO with only a depth texture. If it fails, fallback to a color texture.
    if (
      shadowMap._usesDepthTexture &&
      shadowMap._passes[0].framebuffer.status !==
        WebGLConstants$1.FRAMEBUFFER_COMPLETE
    ) {
      shadowMap._usesDepthTexture = false;
      createRenderStates$5(shadowMap);
      destroyFramebuffer$1(shadowMap);
      createFramebuffer$3(shadowMap, context);
    }
  }

  function updateFramebuffer(shadowMap, context) {
    if (
      !defined(shadowMap._passes[0].framebuffer) ||
      shadowMap._shadowMapTexture.width !== shadowMap._textureSize.x
    ) {
      destroyFramebuffer$1(shadowMap);
      createFramebuffer$3(shadowMap, context);
      checkFramebuffer(shadowMap, context);
      clearFramebuffer(shadowMap, context);
    }
  }

  function clearFramebuffer(shadowMap, context, shadowPass) {
    shadowPass = defaultValue(shadowPass, 0);
    if (shadowMap._isPointLight || shadowPass === 0) {
      shadowMap._clearCommand.framebuffer =
        shadowMap._passes[shadowPass].framebuffer;
      shadowMap._clearCommand.execute(context, shadowMap._clearPassState);
    }
  }

  function resize(shadowMap, size) {
    shadowMap._size = size;
    var passes = shadowMap._passes;
    var numberOfPasses = passes.length;
    var textureSize = shadowMap._textureSize;

    if (shadowMap._isPointLight) {
      size =
        ContextLimits.maximumCubeMapSize >= size
          ? size
          : ContextLimits.maximumCubeMapSize;
      textureSize.x = size;
      textureSize.y = size;
      var faceViewport = new BoundingRectangle(0, 0, size, size);
      passes[0].passState.viewport = faceViewport;
      passes[1].passState.viewport = faceViewport;
      passes[2].passState.viewport = faceViewport;
      passes[3].passState.viewport = faceViewport;
      passes[4].passState.viewport = faceViewport;
      passes[5].passState.viewport = faceViewport;
    } else if (numberOfPasses === 1) {
      // +----+
      // |  1 |
      // +----+
      size =
        ContextLimits.maximumTextureSize >= size
          ? size
          : ContextLimits.maximumTextureSize;
      textureSize.x = size;
      textureSize.y = size;
      passes[0].passState.viewport = new BoundingRectangle(0, 0, size, size);
    } else if (numberOfPasses === 4) {
      // +----+----+
      // |  3 |  4 |
      // +----+----+
      // |  1 |  2 |
      // +----+----+
      size =
        ContextLimits.maximumTextureSize >= size * 2
          ? size
          : ContextLimits.maximumTextureSize / 2;
      textureSize.x = size * 2;
      textureSize.y = size * 2;
      passes[0].passState.viewport = new BoundingRectangle(0, 0, size, size);
      passes[1].passState.viewport = new BoundingRectangle(size, 0, size, size);
      passes[2].passState.viewport = new BoundingRectangle(0, size, size, size);
      passes[3].passState.viewport = new BoundingRectangle(
        size,
        size,
        size,
        size
      );
    }

    // Update clear pass state
    shadowMap._clearPassState.viewport = new BoundingRectangle(
      0,
      0,
      textureSize.x,
      textureSize.y
    );

    // Transforms shadow coordinates [0, 1] into the pass's region of the texture
    for (var i = 0; i < numberOfPasses; ++i) {
      var pass = passes[i];
      var viewport = pass.passState.viewport;
      var biasX = viewport.x / textureSize.x;
      var biasY = viewport.y / textureSize.y;
      var scaleX = viewport.width / textureSize.x;
      var scaleY = viewport.height / textureSize.y;
      pass.textureOffsets = new Matrix4(
        scaleX,
        0.0,
        0.0,
        biasX,
        0.0,
        scaleY,
        0.0,
        biasY,
        0.0,
        0.0,
        1.0,
        0.0,
        0.0,
        0.0,
        0.0,
        1.0
      );
    }
  }

  var scratchViewport$2 = new BoundingRectangle();

  function createDebugShadowViewCommand(shadowMap, context) {
    var fs;
    if (shadowMap._isPointLight) {
      fs =
        "uniform samplerCube shadowMap_textureCube; \n" +
        "varying vec2 v_textureCoordinates; \n" +
        "void main() \n" +
        "{ \n" +
        "    vec2 uv = v_textureCoordinates; \n" +
        "    vec3 dir; \n" +
        " \n" +
        "    if (uv.y < 0.5) \n" +
        "    { \n" +
        "        if (uv.x < 0.333) \n" +
        "        { \n" +
        "            dir.x = -1.0; \n" +
        "            dir.y = uv.x * 6.0 - 1.0; \n" +
        "            dir.z = uv.y * 4.0 - 1.0; \n" +
        "        } \n" +
        "        else if (uv.x < 0.666) \n" +
        "        { \n" +
        "            dir.y = -1.0; \n" +
        "            dir.x = uv.x * 6.0 - 3.0; \n" +
        "            dir.z = uv.y * 4.0 - 1.0; \n" +
        "        } \n" +
        "        else \n" +
        "        { \n" +
        "            dir.z = -1.0; \n" +
        "            dir.x = uv.x * 6.0 - 5.0; \n" +
        "            dir.y = uv.y * 4.0 - 1.0; \n" +
        "        } \n" +
        "    } \n" +
        "    else \n" +
        "    { \n" +
        "        if (uv.x < 0.333) \n" +
        "        { \n" +
        "            dir.x = 1.0; \n" +
        "            dir.y = uv.x * 6.0 - 1.0; \n" +
        "            dir.z = uv.y * 4.0 - 3.0; \n" +
        "        } \n" +
        "        else if (uv.x < 0.666) \n" +
        "        { \n" +
        "            dir.y = 1.0; \n" +
        "            dir.x = uv.x * 6.0 - 3.0; \n" +
        "            dir.z = uv.y * 4.0 - 3.0; \n" +
        "        } \n" +
        "        else \n" +
        "        { \n" +
        "            dir.z = 1.0; \n" +
        "            dir.x = uv.x * 6.0 - 5.0; \n" +
        "            dir.y = uv.y * 4.0 - 3.0; \n" +
        "        } \n" +
        "    } \n" +
        " \n" +
        "    float shadow = czm_unpackDepth(textureCube(shadowMap_textureCube, dir)); \n" +
        "    gl_FragColor = vec4(vec3(shadow), 1.0); \n" +
        "} \n";
    } else {
      fs =
        "uniform sampler2D shadowMap_texture; \n" +
        "varying vec2 v_textureCoordinates; \n" +
        "void main() \n" +
        "{ \n" +
        (shadowMap._usesDepthTexture
          ? "    float shadow = texture2D(shadowMap_texture, v_textureCoordinates).r; \n"
          : "    float shadow = czm_unpackDepth(texture2D(shadowMap_texture, v_textureCoordinates)); \n") +
        "    gl_FragColor = vec4(vec3(shadow), 1.0); \n" +
        "} \n";
    }

    var drawCommand = context.createViewportQuadCommand(fs, {
      uniformMap: {
        shadowMap_texture: function () {
          return shadowMap._shadowMapTexture;
        },
        shadowMap_textureCube: function () {
          return shadowMap._shadowMapTexture;
        },
      },
    });
    drawCommand.pass = Pass$1.OVERLAY;
    return drawCommand;
  }

  function updateDebugShadowViewCommand(shadowMap, frameState) {
    // Draws the shadow map on the bottom-right corner of the screen
    var context = frameState.context;
    var screenWidth = frameState.context.drawingBufferWidth;
    var screenHeight = frameState.context.drawingBufferHeight;
    var size = Math.min(screenWidth, screenHeight) * 0.3;

    var viewport = scratchViewport$2;
    viewport.x = screenWidth - size;
    viewport.y = 0;
    viewport.width = size;
    viewport.height = size;

    var debugCommand = shadowMap._debugShadowViewCommand;
    if (!defined(debugCommand)) {
      debugCommand = createDebugShadowViewCommand(shadowMap, context);
      shadowMap._debugShadowViewCommand = debugCommand;
    }

    // Get a new RenderState for the updated viewport size
    if (
      !defined(debugCommand.renderState) ||
      !BoundingRectangle.equals(debugCommand.renderState.viewport, viewport)
    ) {
      debugCommand.renderState = RenderState.fromCache({
        viewport: BoundingRectangle.clone(viewport),
      });
    }

    frameState.commandList.push(shadowMap._debugShadowViewCommand);
  }

  var frustumCornersNDC$1 = new Array(8);
  frustumCornersNDC$1[0] = new Cartesian4(-1.0, -1.0, -1.0, 1.0);
  frustumCornersNDC$1[1] = new Cartesian4(1.0, -1.0, -1.0, 1.0);
  frustumCornersNDC$1[2] = new Cartesian4(1.0, 1.0, -1.0, 1.0);
  frustumCornersNDC$1[3] = new Cartesian4(-1.0, 1.0, -1.0, 1.0);
  frustumCornersNDC$1[4] = new Cartesian4(-1.0, -1.0, 1.0, 1.0);
  frustumCornersNDC$1[5] = new Cartesian4(1.0, -1.0, 1.0, 1.0);
  frustumCornersNDC$1[6] = new Cartesian4(1.0, 1.0, 1.0, 1.0);
  frustumCornersNDC$1[7] = new Cartesian4(-1.0, 1.0, 1.0, 1.0);

  var scratchMatrix$4 = new Matrix4();
  var scratchFrustumCorners$1 = new Array(8);
  for (var i$5 = 0; i$5 < 8; ++i$5) {
    scratchFrustumCorners$1[i$5] = new Cartesian4();
  }

  function createDebugPointLight(modelMatrix, color) {
    var box = new GeometryInstance({
      geometry: new BoxOutlineGeometry({
        minimum: new Cartesian3(-0.5, -0.5, -0.5),
        maximum: new Cartesian3(0.5, 0.5, 0.5),
      }),
      attributes: {
        color: ColorGeometryInstanceAttribute.fromColor(color),
      },
    });

    var sphere = new GeometryInstance({
      geometry: new SphereOutlineGeometry({
        radius: 0.5,
      }),
      attributes: {
        color: ColorGeometryInstanceAttribute.fromColor(color),
      },
    });

    return new Primitive({
      geometryInstances: [box, sphere],
      appearance: new PerInstanceColorAppearance({
        translucent: false,
        flat: true,
      }),
      asynchronous: false,
      modelMatrix: modelMatrix,
    });
  }

  var debugOutlineColors = [Color.RED, Color.GREEN, Color.BLUE, Color.MAGENTA];
  var scratchScale$8 = new Cartesian3();

  function applyDebugSettings$1(shadowMap, frameState) {
    updateDebugShadowViewCommand(shadowMap, frameState);

    var enterFreezeFrame =
      shadowMap.debugFreezeFrame && !shadowMap._debugFreezeFrame;
    shadowMap._debugFreezeFrame = shadowMap.debugFreezeFrame;

    // Draw scene camera in freeze frame mode
    if (shadowMap.debugFreezeFrame) {
      if (enterFreezeFrame) {
        // Recreate debug camera when entering freeze frame mode
        shadowMap._debugCameraFrustum =
          shadowMap._debugCameraFrustum &&
          shadowMap._debugCameraFrustum.destroy();
        shadowMap._debugCameraFrustum = new DebugCameraPrimitive({
          camera: shadowMap._sceneCamera,
          color: Color.CYAN,
          updateOnChange: false,
        });
      }
      shadowMap._debugCameraFrustum.update(frameState);
    }

    if (shadowMap._cascadesEnabled) {
      // Draw cascades only in freeze frame mode
      if (shadowMap.debugFreezeFrame) {
        if (enterFreezeFrame) {
          // Recreate debug frustum when entering freeze frame mode
          shadowMap._debugLightFrustum =
            shadowMap._debugLightFrustum &&
            shadowMap._debugLightFrustum.destroy();
          shadowMap._debugLightFrustum = new DebugCameraPrimitive({
            camera: shadowMap._shadowMapCamera,
            color: Color.YELLOW,
            updateOnChange: false,
          });
        }
        shadowMap._debugLightFrustum.update(frameState);

        for (var i = 0; i < shadowMap._numberOfCascades; ++i) {
          if (enterFreezeFrame) {
            // Recreate debug frustum when entering freeze frame mode
            shadowMap._debugCascadeFrustums[i] =
              shadowMap._debugCascadeFrustums[i] &&
              shadowMap._debugCascadeFrustums[i].destroy();
            shadowMap._debugCascadeFrustums[i] = new DebugCameraPrimitive({
              camera: shadowMap._passes[i].camera,
              color: debugOutlineColors[i],
              updateOnChange: false,
            });
          }
          shadowMap._debugCascadeFrustums[i].update(frameState);
        }
      }
    } else if (shadowMap._isPointLight) {
      if (!defined(shadowMap._debugLightFrustum) || shadowMap._needsUpdate) {
        var translation = shadowMap._shadowMapCamera.positionWC;
        var rotation = Quaternion.IDENTITY;
        var uniformScale = shadowMap._pointLightRadius * 2.0;
        var scale = Cartesian3.fromElements(
          uniformScale,
          uniformScale,
          uniformScale,
          scratchScale$8
        );
        var modelMatrix = Matrix4.fromTranslationQuaternionRotationScale(
          translation,
          rotation,
          scale,
          scratchMatrix$4
        );

        shadowMap._debugLightFrustum =
          shadowMap._debugLightFrustum && shadowMap._debugLightFrustum.destroy();
        shadowMap._debugLightFrustum = createDebugPointLight(
          modelMatrix,
          Color.YELLOW
        );
      }
      shadowMap._debugLightFrustum.update(frameState);
    } else {
      if (!defined(shadowMap._debugLightFrustum) || shadowMap._needsUpdate) {
        shadowMap._debugLightFrustum = new DebugCameraPrimitive({
          camera: shadowMap._shadowMapCamera,
          color: Color.YELLOW,
          updateOnChange: false,
        });
      }
      shadowMap._debugLightFrustum.update(frameState);
    }
  }

  function ShadowMapCamera() {
    this.viewMatrix = new Matrix4();
    this.inverseViewMatrix = new Matrix4();
    this.frustum = undefined;
    this.positionCartographic = new Cartographic();
    this.positionWC = new Cartesian3();
    this.directionWC = Cartesian3.clone(Cartesian3.UNIT_Z);
    this.upWC = Cartesian3.clone(Cartesian3.UNIT_Y);
    this.rightWC = Cartesian3.clone(Cartesian3.UNIT_X);
    this.viewProjectionMatrix = new Matrix4();
  }

  ShadowMapCamera.prototype.clone = function (camera) {
    Matrix4.clone(camera.viewMatrix, this.viewMatrix);
    Matrix4.clone(camera.inverseViewMatrix, this.inverseViewMatrix);
    this.frustum = camera.frustum.clone(this.frustum);
    Cartographic.clone(camera.positionCartographic, this.positionCartographic);
    Cartesian3.clone(camera.positionWC, this.positionWC);
    Cartesian3.clone(camera.directionWC, this.directionWC);
    Cartesian3.clone(camera.upWC, this.upWC);
    Cartesian3.clone(camera.rightWC, this.rightWC);
  };

  // Converts from NDC space to texture space
  var scaleBiasMatrix = new Matrix4(
    0.5,
    0.0,
    0.0,
    0.5,
    0.0,
    0.5,
    0.0,
    0.5,
    0.0,
    0.0,
    0.5,
    0.5,
    0.0,
    0.0,
    0.0,
    1.0
  );

  ShadowMapCamera.prototype.getViewProjection = function () {
    var view = this.viewMatrix;
    var projection = this.frustum.projectionMatrix;
    Matrix4.multiply(projection, view, this.viewProjectionMatrix);
    Matrix4.multiply(
      scaleBiasMatrix,
      this.viewProjectionMatrix,
      this.viewProjectionMatrix
    );
    return this.viewProjectionMatrix;
  };

  var scratchSplits$1 = new Array(5);
  var scratchFrustum = new PerspectiveFrustum();
  var scratchCascadeDistances = new Array(4);
  var scratchMin$3 = new Cartesian3();
  var scratchMax$3 = new Cartesian3();

  function computeCascades(shadowMap, frameState) {
    var shadowMapCamera = shadowMap._shadowMapCamera;
    var sceneCamera = shadowMap._sceneCamera;
    var cameraNear = sceneCamera.frustum.near;
    var cameraFar = sceneCamera.frustum.far;
    var numberOfCascades = shadowMap._numberOfCascades;

    // Split cascades. Use a mix of linear and log splits.
    var i;
    var range = cameraFar - cameraNear;
    var ratio = cameraFar / cameraNear;

    var lambda = 0.9;
    var clampCascadeDistances = false;

    // When the camera is close to a relatively small model, provide more detail in the closer cascades.
    // If the camera is near or inside a large model, such as the root tile of a city, then use the default values.
    // To get the most accurate cascade splits we would need to find the min and max values from the depth texture.
    if (frameState.shadowState.closestObjectSize < 200.0) {
      clampCascadeDistances = true;
      lambda = 0.9;
    }

    var cascadeDistances = scratchCascadeDistances;
    var splits = scratchSplits$1;
    splits[0] = cameraNear;
    splits[numberOfCascades] = cameraFar;

    // Find initial splits
    for (i = 0; i < numberOfCascades; ++i) {
      var p = (i + 1) / numberOfCascades;
      var logScale = cameraNear * Math.pow(ratio, p);
      var uniformScale = cameraNear + range * p;
      var split = CesiumMath.lerp(uniformScale, logScale, lambda);
      splits[i + 1] = split;
      cascadeDistances[i] = split - splits[i];
    }

    if (clampCascadeDistances) {
      // Clamp each cascade to its maximum distance
      for (i = 0; i < numberOfCascades; ++i) {
        cascadeDistances[i] = Math.min(
          cascadeDistances[i],
          shadowMap._maximumCascadeDistances[i]
        );
      }

      // Recompute splits
      var distance = splits[0];
      for (i = 0; i < numberOfCascades - 1; ++i) {
        distance += cascadeDistances[i];
        splits[i + 1] = distance;
      }
    }

    Cartesian4.unpack(splits, 0, shadowMap._cascadeSplits[0]);
    Cartesian4.unpack(splits, 1, shadowMap._cascadeSplits[1]);
    Cartesian4.unpack(cascadeDistances, 0, shadowMap._cascadeDistances);

    var shadowFrustum = shadowMapCamera.frustum;
    var left = shadowFrustum.left;
    var right = shadowFrustum.right;
    var bottom = shadowFrustum.bottom;
    var top = shadowFrustum.top;
    var near = shadowFrustum.near;
    var far = shadowFrustum.far;

    var position = shadowMapCamera.positionWC;
    var direction = shadowMapCamera.directionWC;
    var up = shadowMapCamera.upWC;

    var cascadeSubFrustum = sceneCamera.frustum.clone(scratchFrustum);
    var shadowViewProjection = shadowMapCamera.getViewProjection();

    for (i = 0; i < numberOfCascades; ++i) {
      // Find the bounding box of the camera sub-frustum in shadow map texture space
      cascadeSubFrustum.near = splits[i];
      cascadeSubFrustum.far = splits[i + 1];
      var viewProjection = Matrix4.multiply(
        cascadeSubFrustum.projectionMatrix,
        sceneCamera.viewMatrix,
        scratchMatrix$4
      );
      var inverseViewProjection = Matrix4.inverse(viewProjection, scratchMatrix$4);
      var shadowMapMatrix = Matrix4.multiply(
        shadowViewProjection,
        inverseViewProjection,
        scratchMatrix$4
      );

      // Project each corner from camera NDC space to shadow map texture space. Min and max will be from 0 to 1.
      var min = Cartesian3.fromElements(
        Number.MAX_VALUE,
        Number.MAX_VALUE,
        Number.MAX_VALUE,
        scratchMin$3
      );
      var max = Cartesian3.fromElements(
        -Number.MAX_VALUE,
        -Number.MAX_VALUE,
        -Number.MAX_VALUE,
        scratchMax$3
      );

      for (var k = 0; k < 8; ++k) {
        var corner = Cartesian4.clone(
          frustumCornersNDC$1[k],
          scratchFrustumCorners$1[k]
        );
        Matrix4.multiplyByVector(shadowMapMatrix, corner, corner);
        Cartesian3.divideByScalar(corner, corner.w, corner); // Handle the perspective divide
        Cartesian3.minimumByComponent(corner, min, min);
        Cartesian3.maximumByComponent(corner, max, max);
      }

      // Limit light-space coordinates to the [0, 1] range
      min.x = Math.max(min.x, 0.0);
      min.y = Math.max(min.y, 0.0);
      min.z = 0.0; // Always start cascade frustum at the top of the light frustum to capture objects in the light's path
      max.x = Math.min(max.x, 1.0);
      max.y = Math.min(max.y, 1.0);
      max.z = Math.min(max.z, 1.0);

      var pass = shadowMap._passes[i];
      var cascadeCamera = pass.camera;
      cascadeCamera.clone(shadowMapCamera); // PERFORMANCE_IDEA : could do a shallow clone for all properties except the frustum

      var frustum = cascadeCamera.frustum;
      frustum.left = left + min.x * (right - left);
      frustum.right = left + max.x * (right - left);
      frustum.bottom = bottom + min.y * (top - bottom);
      frustum.top = bottom + max.y * (top - bottom);
      frustum.near = near + min.z * (far - near);
      frustum.far = near + max.z * (far - near);

      pass.cullingVolume = cascadeCamera.frustum.computeCullingVolume(
        position,
        direction,
        up
      );

      // Transforms from eye space to the cascade's texture space
      var cascadeMatrix = shadowMap._cascadeMatrices[i];
      Matrix4.multiply(
        cascadeCamera.getViewProjection(),
        sceneCamera.inverseViewMatrix,
        cascadeMatrix
      );
      Matrix4.multiply(pass.textureOffsets, cascadeMatrix, cascadeMatrix);
    }
  }

  var scratchLightView = new Matrix4();
  var scratchRight$2 = new Cartesian3();
  var scratchUp = new Cartesian3();
  var scratchTranslation$1 = new Cartesian3();

  function fitShadowMapToScene(shadowMap, frameState) {
    var shadowMapCamera = shadowMap._shadowMapCamera;
    var sceneCamera = shadowMap._sceneCamera;

    // 1. First find a tight bounding box in light space that contains the entire camera frustum.
    var viewProjection = Matrix4.multiply(
      sceneCamera.frustum.projectionMatrix,
      sceneCamera.viewMatrix,
      scratchMatrix$4
    );
    var inverseViewProjection = Matrix4.inverse(viewProjection, scratchMatrix$4);

    // Start to construct the light view matrix. Set translation later once the bounding box is found.
    var lightDir = shadowMapCamera.directionWC;
    var lightUp = sceneCamera.directionWC; // Align shadows to the camera view.
    if (Cartesian3.equalsEpsilon(lightDir, lightUp, CesiumMath.EPSILON10)) {
      lightUp = sceneCamera.upWC;
    }
    var lightRight = Cartesian3.cross(lightDir, lightUp, scratchRight$2);
    lightUp = Cartesian3.cross(lightRight, lightDir, scratchUp); // Recalculate up now that right is derived
    Cartesian3.normalize(lightUp, lightUp);
    Cartesian3.normalize(lightRight, lightRight);
    var lightPosition = Cartesian3.fromElements(
      0.0,
      0.0,
      0.0,
      scratchTranslation$1
    );

    var lightView = Matrix4.computeView(
      lightPosition,
      lightDir,
      lightUp,
      lightRight,
      scratchLightView
    );
    var cameraToLight = Matrix4.multiply(
      lightView,
      inverseViewProjection,
      scratchMatrix$4
    );

    // Project each corner from NDC space to light view space, and calculate a min and max in light view space
    var min = Cartesian3.fromElements(
      Number.MAX_VALUE,
      Number.MAX_VALUE,
      Number.MAX_VALUE,
      scratchMin$3
    );
    var max = Cartesian3.fromElements(
      -Number.MAX_VALUE,
      -Number.MAX_VALUE,
      -Number.MAX_VALUE,
      scratchMax$3
    );

    for (var i = 0; i < 8; ++i) {
      var corner = Cartesian4.clone(
        frustumCornersNDC$1[i],
        scratchFrustumCorners$1[i]
      );
      Matrix4.multiplyByVector(cameraToLight, corner, corner);
      Cartesian3.divideByScalar(corner, corner.w, corner); // Handle the perspective divide
      Cartesian3.minimumByComponent(corner, min, min);
      Cartesian3.maximumByComponent(corner, max, max);
    }

    // 2. Set bounding box back to include objects in the light's view
    max.z += 1000.0; // Note: in light space, a positive number is behind the camera
    min.z -= 10.0; // Extend the shadow volume forward slightly to avoid problems right at the edge

    // 3. Adjust light view matrix so that it is centered on the bounding volume
    var translation = scratchTranslation$1;
    translation.x = -(0.5 * (min.x + max.x));
    translation.y = -(0.5 * (min.y + max.y));
    translation.z = -max.z;

    var translationMatrix = Matrix4.fromTranslation(translation, scratchMatrix$4);
    lightView = Matrix4.multiply(translationMatrix, lightView, lightView);

    // 4. Create an orthographic frustum that covers the bounding box extents
    var halfWidth = 0.5 * (max.x - min.x);
    var halfHeight = 0.5 * (max.y - min.y);
    var depth = max.z - min.z;

    var frustum = shadowMapCamera.frustum;
    frustum.left = -halfWidth;
    frustum.right = halfWidth;
    frustum.bottom = -halfHeight;
    frustum.top = halfHeight;
    frustum.near = 0.01;
    frustum.far = depth;

    // 5. Update the shadow map camera
    Matrix4.clone(lightView, shadowMapCamera.viewMatrix);
    Matrix4.inverse(lightView, shadowMapCamera.inverseViewMatrix);
    Matrix4.getTranslation(
      shadowMapCamera.inverseViewMatrix,
      shadowMapCamera.positionWC
    );
    frameState.mapProjection.ellipsoid.cartesianToCartographic(
      shadowMapCamera.positionWC,
      shadowMapCamera.positionCartographic
    );
    Cartesian3.clone(lightDir, shadowMapCamera.directionWC);
    Cartesian3.clone(lightUp, shadowMapCamera.upWC);
    Cartesian3.clone(lightRight, shadowMapCamera.rightWC);
  }

  var directions = [
    new Cartesian3(-1.0, 0.0, 0.0),
    new Cartesian3(0.0, -1.0, 0.0),
    new Cartesian3(0.0, 0.0, -1.0),
    new Cartesian3(1.0, 0.0, 0.0),
    new Cartesian3(0.0, 1.0, 0.0),
    new Cartesian3(0.0, 0.0, 1.0),
  ];

  var ups = [
    new Cartesian3(0.0, -1.0, 0.0),
    new Cartesian3(0.0, 0.0, -1.0),
    new Cartesian3(0.0, -1.0, 0.0),
    new Cartesian3(0.0, -1.0, 0.0),
    new Cartesian3(0.0, 0.0, 1.0),
    new Cartesian3(0.0, -1.0, 0.0),
  ];

  var rights = [
    new Cartesian3(0.0, 0.0, 1.0),
    new Cartesian3(1.0, 0.0, 0.0),
    new Cartesian3(-1.0, 0.0, 0.0),
    new Cartesian3(0.0, 0.0, -1.0),
    new Cartesian3(1.0, 0.0, 0.0),
    new Cartesian3(1.0, 0.0, 0.0),
  ];

  function computeOmnidirectional(shadowMap, frameState) {
    // All sides share the same frustum
    var frustum = new PerspectiveFrustum();
    frustum.fov = CesiumMath.PI_OVER_TWO;
    frustum.near = 1.0;
    frustum.far = shadowMap._pointLightRadius;
    frustum.aspectRatio = 1.0;

    for (var i = 0; i < 6; ++i) {
      var camera = shadowMap._passes[i].camera;
      camera.positionWC = shadowMap._shadowMapCamera.positionWC;
      camera.positionCartographic = frameState.mapProjection.ellipsoid.cartesianToCartographic(
        camera.positionWC,
        camera.positionCartographic
      );
      camera.directionWC = directions[i];
      camera.upWC = ups[i];
      camera.rightWC = rights[i];

      Matrix4.computeView(
        camera.positionWC,
        camera.directionWC,
        camera.upWC,
        camera.rightWC,
        camera.viewMatrix
      );
      Matrix4.inverse(camera.viewMatrix, camera.inverseViewMatrix);

      camera.frustum = frustum;
    }
  }

  var scratchCartesian1$8 = new Cartesian3();
  var scratchCartesian2$b = new Cartesian3();
  var scratchBoundingSphere$4 = new BoundingSphere();
  var scratchCenter$5 = scratchBoundingSphere$4.center;

  function checkVisibility(shadowMap, frameState) {
    var sceneCamera = shadowMap._sceneCamera;
    var shadowMapCamera = shadowMap._shadowMapCamera;

    var boundingSphere = scratchBoundingSphere$4;

    // Check whether the shadow map is in view and needs to be updated
    if (shadowMap._cascadesEnabled) {
      // If the nearest shadow receiver is further than the shadow map's maximum distance then the shadow map is out of view.
      if (sceneCamera.frustum.near >= shadowMap.maximumDistance) {
        shadowMap._outOfView = true;
        shadowMap._needsUpdate = false;
        return;
      }

      // If the light source is below the horizon then the shadow map is out of view
      var surfaceNormal = frameState.mapProjection.ellipsoid.geodeticSurfaceNormal(
        sceneCamera.positionWC,
        scratchCartesian1$8
      );
      var lightDirection = Cartesian3.negate(
        shadowMapCamera.directionWC,
        scratchCartesian2$b
      );
      var dot = Cartesian3.dot(surfaceNormal, lightDirection);

      // Shadows start to fade out once the light gets closer to the horizon.
      // At this point the globe uses vertex lighting alone to darken the surface.
      var darknessAmount = CesiumMath.clamp(dot / 0.1, 0.0, 1.0);
      shadowMap._darkness = CesiumMath.lerp(
        1.0,
        shadowMap.darkness,
        darknessAmount
      );

      if (dot < 0.0) {
        shadowMap._outOfView = true;
        shadowMap._needsUpdate = false;
        return;
      }

      // By default cascaded shadows need to update and are always in view
      shadowMap._needsUpdate = true;
      shadowMap._outOfView = false;
    } else if (shadowMap._isPointLight) {
      // Sphere-frustum intersection test
      boundingSphere.center = shadowMapCamera.positionWC;
      boundingSphere.radius = shadowMap._pointLightRadius;
      shadowMap._outOfView =
        frameState.cullingVolume.computeVisibility(boundingSphere) ===
        Intersect$1.OUTSIDE;
      shadowMap._needsUpdate =
        !shadowMap._outOfView &&
        !shadowMap._boundingSphere.equals(boundingSphere);
      BoundingSphere.clone(boundingSphere, shadowMap._boundingSphere);
    } else {
      // Simplify frustum-frustum intersection test as a sphere-frustum test
      var frustumRadius = shadowMapCamera.frustum.far / 2.0;
      var frustumCenter = Cartesian3.add(
        shadowMapCamera.positionWC,
        Cartesian3.multiplyByScalar(
          shadowMapCamera.directionWC,
          frustumRadius,
          scratchCenter$5
        ),
        scratchCenter$5
      );
      boundingSphere.center = frustumCenter;
      boundingSphere.radius = frustumRadius;
      shadowMap._outOfView =
        frameState.cullingVolume.computeVisibility(boundingSphere) ===
        Intersect$1.OUTSIDE;
      shadowMap._needsUpdate =
        !shadowMap._outOfView &&
        !shadowMap._boundingSphere.equals(boundingSphere);
      BoundingSphere.clone(boundingSphere, shadowMap._boundingSphere);
    }
  }

  function updateCameras(shadowMap, frameState) {
    var camera = frameState.camera; // The actual camera in the scene
    var lightCamera = shadowMap._lightCamera; // The external camera representing the light source
    var sceneCamera = shadowMap._sceneCamera; // Clone of camera, with clamped near and far planes
    var shadowMapCamera = shadowMap._shadowMapCamera; // Camera representing the shadow volume, initially cloned from lightCamera

    // Clone light camera into the shadow map camera
    if (shadowMap._cascadesEnabled) {
      Cartesian3.clone(lightCamera.directionWC, shadowMapCamera.directionWC);
    } else if (shadowMap._isPointLight) {
      Cartesian3.clone(lightCamera.positionWC, shadowMapCamera.positionWC);
    } else {
      shadowMapCamera.clone(lightCamera);
    }

    // Get the light direction in eye coordinates
    var lightDirection = shadowMap._lightDirectionEC;
    Matrix4.multiplyByPointAsVector(
      camera.viewMatrix,
      shadowMapCamera.directionWC,
      lightDirection
    );
    Cartesian3.normalize(lightDirection, lightDirection);
    Cartesian3.negate(lightDirection, lightDirection);

    // Get the light position in eye coordinates
    Matrix4.multiplyByPoint(
      camera.viewMatrix,
      shadowMapCamera.positionWC,
      shadowMap._lightPositionEC
    );
    shadowMap._lightPositionEC.w = shadowMap._pointLightRadius;

    // Get the near and far of the scene camera
    var near;
    var far;
    if (shadowMap._fitNearFar) {
      // shadowFar can be very large, so limit to shadowMap.maximumDistance
      // Push the far plane slightly further than the near plane to avoid degenerate frustum
      near = Math.min(
        frameState.shadowState.nearPlane,
        shadowMap.maximumDistance
      );
      far = Math.min(
        frameState.shadowState.farPlane,
        shadowMap.maximumDistance + 1.0
      );
    } else {
      near = camera.frustum.near;
      far = shadowMap.maximumDistance;
    }

    shadowMap._sceneCamera = Camera.clone(camera, sceneCamera);
    camera.frustum.clone(shadowMap._sceneCamera.frustum);
    shadowMap._sceneCamera.frustum.near = near;
    shadowMap._sceneCamera.frustum.far = far;
    shadowMap._distance = far - near;

    checkVisibility(shadowMap, frameState);

    if (!shadowMap._outOfViewPrevious && shadowMap._outOfView) {
      shadowMap._needsUpdate = true;
    }
    shadowMap._outOfViewPrevious = shadowMap._outOfView;
  }

  /**
   * @private
   */
  ShadowMap.prototype.update = function (frameState) {
    updateCameras(this, frameState);

    if (this._needsUpdate) {
      updateFramebuffer(this, frameState.context);

      if (this._isPointLight) {
        computeOmnidirectional(this, frameState);
      }

      if (this._cascadesEnabled) {
        fitShadowMapToScene(this, frameState);

        if (this._numberOfCascades > 1) {
          computeCascades(this, frameState);
        }
      }

      if (!this._isPointLight) {
        // Compute the culling volume
        var shadowMapCamera = this._shadowMapCamera;
        var position = shadowMapCamera.positionWC;
        var direction = shadowMapCamera.directionWC;
        var up = shadowMapCamera.upWC;
        this._shadowMapCullingVolume = shadowMapCamera.frustum.computeCullingVolume(
          position,
          direction,
          up
        );

        if (this._passes.length === 1) {
          // Since there is only one pass, use the shadow map camera as the pass camera.
          this._passes[0].camera.clone(shadowMapCamera);
        }
      } else {
        this._shadowMapCullingVolume = CullingVolume.fromBoundingSphere(
          this._boundingSphere
        );
      }
    }

    if (this._passes.length === 1) {
      // Transforms from eye space to shadow texture space.
      // Always requires an update since the scene camera constantly changes.
      var inverseView = this._sceneCamera.inverseViewMatrix;
      Matrix4.multiply(
        this._shadowMapCamera.getViewProjection(),
        inverseView,
        this._shadowMapMatrix
      );
    }

    if (this.debugShow) {
      applyDebugSettings$1(this, frameState);
    }
  };

  /**
   * @private
   */
  ShadowMap.prototype.updatePass = function (context, shadowPass) {
    clearFramebuffer(this, context, shadowPass);
  };

  var scratchTexelStepSize = new Cartesian2();

  function combineUniforms(shadowMap, uniforms, isTerrain) {
    var bias = shadowMap._isPointLight
      ? shadowMap._pointBias
      : isTerrain
      ? shadowMap._terrainBias
      : shadowMap._primitiveBias;

    var mapUniforms = {
      shadowMap_texture: function () {
        return shadowMap._shadowMapTexture;
      },
      shadowMap_textureCube: function () {
        return shadowMap._shadowMapTexture;
      },
      shadowMap_matrix: function () {
        return shadowMap._shadowMapMatrix;
      },
      shadowMap_cascadeSplits: function () {
        return shadowMap._cascadeSplits;
      },
      shadowMap_cascadeMatrices: function () {
        return shadowMap._cascadeMatrices;
      },
      shadowMap_lightDirectionEC: function () {
        return shadowMap._lightDirectionEC;
      },
      shadowMap_lightPositionEC: function () {
        return shadowMap._lightPositionEC;
      },
      shadowMap_cascadeDistances: function () {
        return shadowMap._cascadeDistances;
      },
      shadowMap_texelSizeDepthBiasAndNormalShadingSmooth: function () {
        var texelStepSize = scratchTexelStepSize;
        texelStepSize.x = 1.0 / shadowMap._textureSize.x;
        texelStepSize.y = 1.0 / shadowMap._textureSize.y;

        return Cartesian4.fromElements(
          texelStepSize.x,
          texelStepSize.y,
          bias.depthBias,
          bias.normalShadingSmooth,
          this.combinedUniforms1
        );
      },
      shadowMap_normalOffsetScaleDistanceMaxDistanceAndDarkness: function () {
        return Cartesian4.fromElements(
          bias.normalOffsetScale,
          shadowMap._distance,
          shadowMap.maximumDistance,
          shadowMap._darkness,
          this.combinedUniforms2
        );
      },

      combinedUniforms1: new Cartesian4(),
      combinedUniforms2: new Cartesian4(),
    };

    return combine(uniforms, mapUniforms, false);
  }

  function createCastDerivedCommand(
    shadowMap,
    shadowsDirty,
    command,
    context,
    oldShaderId,
    result
  ) {
    var castShader;
    var castRenderState;
    var castUniformMap;
    if (defined(result)) {
      castShader = result.shaderProgram;
      castRenderState = result.renderState;
      castUniformMap = result.uniformMap;
    }

    result = DrawCommand.shallowClone(command, result);
    result.castShadows = true;
    result.receiveShadows = false;

    if (
      !defined(castShader) ||
      oldShaderId !== command.shaderProgram.id ||
      shadowsDirty
    ) {
      var shaderProgram = command.shaderProgram;

      var isTerrain = command.pass === Pass$1.GLOBE;
      var isOpaque = command.pass !== Pass$1.TRANSLUCENT;
      var isPointLight = shadowMap._isPointLight;
      var usesDepthTexture = shadowMap._usesDepthTexture;

      var keyword = ShadowMapShader.getShadowCastShaderKeyword(
        isPointLight,
        isTerrain,
        usesDepthTexture,
        isOpaque
      );
      castShader = context.shaderCache.getDerivedShaderProgram(
        shaderProgram,
        keyword
      );
      if (!defined(castShader)) {
        var vertexShaderSource = shaderProgram.vertexShaderSource;
        var fragmentShaderSource = shaderProgram.fragmentShaderSource;

        var castVS = ShadowMapShader.createShadowCastVertexShader(
          vertexShaderSource,
          isPointLight,
          isTerrain
        );
        var castFS = ShadowMapShader.createShadowCastFragmentShader(
          fragmentShaderSource,
          isPointLight,
          usesDepthTexture,
          isOpaque
        );

        castShader = context.shaderCache.createDerivedShaderProgram(
          shaderProgram,
          keyword,
          {
            vertexShaderSource: castVS,
            fragmentShaderSource: castFS,
            attributeLocations: shaderProgram._attributeLocations,
          }
        );
      }

      castRenderState = shadowMap._primitiveRenderState;
      if (isPointLight) {
        castRenderState = shadowMap._pointRenderState;
      } else if (isTerrain) {
        castRenderState = shadowMap._terrainRenderState;
      }

      // Modify the render state for commands that do not use back-face culling, e.g. flat textured walls
      var cullEnabled = command.renderState.cull.enabled;
      if (!cullEnabled) {
        castRenderState = clone(castRenderState, false);
        castRenderState.cull = clone(castRenderState.cull, false);
        castRenderState.cull.enabled = false;
        castRenderState = RenderState.fromCache(castRenderState);
      }

      castUniformMap = combineUniforms(shadowMap, command.uniformMap, isTerrain);
    }

    result.shaderProgram = castShader;
    result.renderState = castRenderState;
    result.uniformMap = castUniformMap;

    return result;
  }

  ShadowMap.createReceiveDerivedCommand = function (
    lightShadowMaps,
    command,
    shadowsDirty,
    context,
    result
  ) {
    if (!defined(result)) {
      result = {};
    }

    var lightShadowMapsEnabled = lightShadowMaps.length > 0;
    var shaderProgram = command.shaderProgram;
    var vertexShaderSource = shaderProgram.vertexShaderSource;
    var fragmentShaderSource = shaderProgram.fragmentShaderSource;
    var isTerrain = command.pass === Pass$1.GLOBE;

    var hasTerrainNormal = false;
    if (isTerrain) {
      hasTerrainNormal =
        command.owner.data.renderedMesh.encoding.hasVertexNormals;
    }

    if (command.receiveShadows && lightShadowMapsEnabled) {
      // Only generate a receiveCommand if there is a shadow map originating from a light source.
      var receiveShader;
      var receiveUniformMap;
      if (defined(result.receiveCommand)) {
        receiveShader = result.receiveCommand.shaderProgram;
        receiveUniformMap = result.receiveCommand.uniformMap;
      }

      result.receiveCommand = DrawCommand.shallowClone(
        command,
        result.receiveCommand
      );
      result.castShadows = false;
      result.receiveShadows = true;

      // If castShadows changed, recompile the receive shadows shader. The normal shading technique simulates
      // self-shadowing so it should be turned off if castShadows is false.
      var castShadowsDirty =
        result.receiveShaderCastShadows !== command.castShadows;
      var shaderDirty =
        result.receiveShaderProgramId !== command.shaderProgram.id;

      if (
        !defined(receiveShader) ||
        shaderDirty ||
        shadowsDirty ||
        castShadowsDirty
      ) {
        var keyword = ShadowMapShader.getShadowReceiveShaderKeyword(
          lightShadowMaps[0],
          command.castShadows,
          isTerrain,
          hasTerrainNormal
        );
        receiveShader = context.shaderCache.getDerivedShaderProgram(
          shaderProgram,
          keyword
        );
        if (!defined(receiveShader)) {
          var receiveVS = ShadowMapShader.createShadowReceiveVertexShader(
            vertexShaderSource,
            isTerrain,
            hasTerrainNormal
          );
          var receiveFS = ShadowMapShader.createShadowReceiveFragmentShader(
            fragmentShaderSource,
            lightShadowMaps[0],
            command.castShadows,
            isTerrain,
            hasTerrainNormal
          );

          receiveShader = context.shaderCache.createDerivedShaderProgram(
            shaderProgram,
            keyword,
            {
              vertexShaderSource: receiveVS,
              fragmentShaderSource: receiveFS,
              attributeLocations: shaderProgram._attributeLocations,
            }
          );
        }

        receiveUniformMap = combineUniforms(
          lightShadowMaps[0],
          command.uniformMap,
          isTerrain
        );
      }

      result.receiveCommand.shaderProgram = receiveShader;
      result.receiveCommand.uniformMap = receiveUniformMap;
      result.receiveShaderProgramId = command.shaderProgram.id;
      result.receiveShaderCastShadows = command.castShadows;
    }

    return result;
  };

  ShadowMap.createCastDerivedCommand = function (
    shadowMaps,
    command,
    shadowsDirty,
    context,
    result
  ) {
    if (!defined(result)) {
      result = {};
    }

    if (command.castShadows) {
      var castCommands = result.castCommands;
      if (!defined(castCommands)) {
        castCommands = result.castCommands = [];
      }

      var oldShaderId = result.castShaderProgramId;

      var shadowMapLength = shadowMaps.length;
      castCommands.length = shadowMapLength;

      for (var i = 0; i < shadowMapLength; ++i) {
        castCommands[i] = createCastDerivedCommand(
          shadowMaps[i],
          shadowsDirty,
          command,
          context,
          oldShaderId,
          castCommands[i]
        );
      }

      result.castShaderProgramId = command.shaderProgram.id;
    }

    return result;
  };

  /**
   * @private
   */
  ShadowMap.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * @private
   */
  ShadowMap.prototype.destroy = function () {
    destroyFramebuffer$1(this);

    this._debugLightFrustum =
      this._debugLightFrustum && this._debugLightFrustum.destroy();
    this._debugCameraFrustum =
      this._debugCameraFrustum && this._debugCameraFrustum.destroy();
    this._debugShadowViewCommand =
      this._debugShadowViewCommand &&
      this._debugShadowViewCommand.shaderProgram &&
      this._debugShadowViewCommand.shaderProgram.destroy();

    for (var i = 0; i < this._numberOfCascades; ++i) {
      this._debugCascadeFrustums[i] =
        this._debugCascadeFrustums[i] && this._debugCascadeFrustums[i].destroy();
    }

    return destroyObject(this);
  };

  function CommandExtent() {
    this.command = undefined;
    this.near = undefined;
    this.far = undefined;
  }

  /**
   * @private
   */
  function View(scene, camera, viewport) {
    var context = scene.context;

    var globeDepth;
    if (context.depthTexture) {
      globeDepth = new GlobeDepth();
    }

    var oit;
    if (scene._useOIT && context.depthTexture) {
      oit = new OIT(context);
    }

    var passState = new PassState(context);
    passState.viewport = BoundingRectangle.clone(viewport);

    this.camera = camera;
    this._cameraClone = Camera.clone(camera);
    this._cameraStartFired = false;
    this._cameraMovedTime = undefined;

    this.viewport = viewport;
    this.passState = passState;
    this.pickFramebuffer = new PickFramebuffer(context);
    this.pickDepthFramebuffer = new PickDepthFramebuffer();
    this.sceneFramebuffer = new SceneFramebuffer();
    this.globeDepth = globeDepth;
    this.globeTranslucencyFramebuffer = new GlobeTranslucencyFramebuffer();
    this.oit = oit;
    this.pickDepths = [];
    this.debugGlobeDepths = [];
    this.frustumCommandsList = [];
    this.debugFrustumStatistics = undefined;

    // Array of all commands that get rendered into frustums along with their near / far values.
    // Acts similar to a ManagedArray.
    this._commandExtents = [];
  }

  var scratchPosition0 = new Cartesian3();
  var scratchPosition1 = new Cartesian3();
  function maxComponent(a, b) {
    var x = Math.max(Math.abs(a.x), Math.abs(b.x));
    var y = Math.max(Math.abs(a.y), Math.abs(b.y));
    var z = Math.max(Math.abs(a.z), Math.abs(b.z));
    return Math.max(Math.max(x, y), z);
  }

  function cameraEqual(camera0, camera1, epsilon) {
    var scalar =
      1 / Math.max(1, maxComponent(camera0.position, camera1.position));
    Cartesian3.multiplyByScalar(camera0.position, scalar, scratchPosition0);
    Cartesian3.multiplyByScalar(camera1.position, scalar, scratchPosition1);
    return (
      Cartesian3.equalsEpsilon(scratchPosition0, scratchPosition1, epsilon) &&
      Cartesian3.equalsEpsilon(camera0.direction, camera1.direction, epsilon) &&
      Cartesian3.equalsEpsilon(camera0.up, camera1.up, epsilon) &&
      Cartesian3.equalsEpsilon(camera0.right, camera1.right, epsilon) &&
      Matrix4.equalsEpsilon(camera0.transform, camera1.transform, epsilon) &&
      camera0.frustum.equalsEpsilon(camera1.frustum, epsilon)
    );
  }

  View.prototype.checkForCameraUpdates = function (scene) {
    var camera = this.camera;
    var cameraClone = this._cameraClone;
    if (!cameraEqual(camera, cameraClone, CesiumMath.EPSILON15)) {
      if (!this._cameraStartFired) {
        camera.moveStart.raiseEvent();
        this._cameraStartFired = true;
      }
      this._cameraMovedTime = getTimestamp$1();
      Camera.clone(camera, cameraClone);

      return true;
    }

    if (
      this._cameraStartFired &&
      getTimestamp$1() - this._cameraMovedTime > scene.cameraEventWaitTime
    ) {
      camera.moveEnd.raiseEvent();
      this._cameraStartFired = false;
    }

    return false;
  };

  function updateFrustums(view, scene, near, far) {
    var frameState = scene.frameState;
    var camera = frameState.camera;
    var farToNearRatio = frameState.useLogDepth
      ? scene.logarithmicDepthFarToNearRatio
      : scene.farToNearRatio;
    var is2D = scene.mode === SceneMode$1.SCENE2D;
    var nearToFarDistance2D = scene.nearToFarDistance2D;

    // The computed near plane must be between the user defined near and far planes.
    // The computed far plane must between the user defined far and computed near.
    // This will handle the case where the computed near plane is further than the user defined far plane.
    near = Math.min(Math.max(near, camera.frustum.near), camera.frustum.far);
    far = Math.max(Math.min(far, camera.frustum.far), near);

    var numFrustums;
    if (is2D) {
      // The multifrustum for 2D is uniformly distributed. To avoid z-fighting in 2D,
      // the camera is moved to just before the frustum and the frustum depth is scaled
      // to be in [1.0, nearToFarDistance2D].
      far = Math.min(far, camera.position.z + scene.nearToFarDistance2D);
      near = Math.min(near, far);
      numFrustums = Math.ceil(
        Math.max(1.0, far - near) / scene.nearToFarDistance2D
      );
    } else {
      // The multifrustum for 3D/CV is non-uniformly distributed.
      numFrustums = Math.ceil(Math.log(far / near) / Math.log(farToNearRatio));
    }

    var frustumCommandsList = view.frustumCommandsList;
    frustumCommandsList.length = numFrustums;
    for (var m = 0; m < numFrustums; ++m) {
      var curNear;
      var curFar;

      if (is2D) {
        curNear = Math.min(
          far - nearToFarDistance2D,
          near + m * nearToFarDistance2D
        );
        curFar = Math.min(far, curNear + nearToFarDistance2D);
      } else {
        curNear = Math.max(near, Math.pow(farToNearRatio, m) * near);
        curFar = Math.min(far, farToNearRatio * curNear);
      }
      var frustumCommands = frustumCommandsList[m];
      if (!defined(frustumCommands)) {
        frustumCommands = frustumCommandsList[m] = new FrustumCommands(
          curNear,
          curFar
        );
      } else {
        frustumCommands.near = curNear;
        frustumCommands.far = curFar;
      }
    }
  }

  function insertIntoBin(view, scene, command, commandNear, commandFar) {
    if (scene.debugShowFrustums) {
      command.debugOverlappingFrustums = 0;
    }

    var frustumCommandsList = view.frustumCommandsList;
    var length = frustumCommandsList.length;

    for (var i = 0; i < length; ++i) {
      var frustumCommands = frustumCommandsList[i];
      var curNear = frustumCommands.near;
      var curFar = frustumCommands.far;

      if (commandNear > curFar) {
        continue;
      }

      if (commandFar < curNear) {
        break;
      }

      var pass = command.pass;
      var index = frustumCommands.indices[pass]++;
      frustumCommands.commands[pass][index] = command;

      if (scene.debugShowFrustums) {
        command.debugOverlappingFrustums |= 1 << i;
      }

      if (command.executeInClosestFrustum) {
        break;
      }
    }

    if (scene.debugShowFrustums) {
      var cf = view.debugFrustumStatistics.commandsInFrustums;
      cf[command.debugOverlappingFrustums] = defined(
        cf[command.debugOverlappingFrustums]
      )
        ? cf[command.debugOverlappingFrustums] + 1
        : 1;
      ++view.debugFrustumStatistics.totalCommands;
    }

    scene.updateDerivedCommands(command);
  }

  var scratchCullingVolume = new CullingVolume();
  var scratchNearFarInterval = new Interval();

  View.prototype.createPotentiallyVisibleSet = function (scene) {
    var frameState = scene.frameState;
    var camera = frameState.camera;
    var direction = camera.directionWC;
    var position = camera.positionWC;

    var computeList = scene._computeCommandList;
    var overlayList = scene._overlayCommandList;
    var commandList = frameState.commandList;

    if (scene.debugShowFrustums) {
      this.debugFrustumStatistics = {
        totalCommands: 0,
        commandsInFrustums: {},
      };
    }

    var frustumCommandsList = this.frustumCommandsList;
    var numberOfFrustums = frustumCommandsList.length;
    var numberOfPasses = Pass$1.NUMBER_OF_PASSES;
    for (var n = 0; n < numberOfFrustums; ++n) {
      for (var p = 0; p < numberOfPasses; ++p) {
        frustumCommandsList[n].indices[p] = 0;
      }
    }

    computeList.length = 0;
    overlayList.length = 0;

    var commandExtents = this._commandExtents;
    var commandExtentCapacity = commandExtents.length;
    var commandExtentCount = 0;

    var near = +Number.MAX_VALUE;
    var far = -Number.MAX_VALUE;

    var shadowsEnabled = frameState.shadowState.shadowsEnabled;
    var shadowNear = +Number.MAX_VALUE;
    var shadowFar = -Number.MAX_VALUE;
    var shadowClosestObjectSize = Number.MAX_VALUE;

    var occluder =
      frameState.mode === SceneMode$1.SCENE3D ? frameState.occluder : undefined;
    var cullingVolume = frameState.cullingVolume;

    // get user culling volume minus the far plane.
    var planes = scratchCullingVolume.planes;
    for (var k = 0; k < 5; ++k) {
      planes[k] = cullingVolume.planes[k];
    }
    cullingVolume = scratchCullingVolume;

    var length = commandList.length;
    for (var i = 0; i < length; ++i) {
      var command = commandList[i];
      var pass = command.pass;

      if (pass === Pass$1.COMPUTE) {
        computeList.push(command);
      } else if (pass === Pass$1.OVERLAY) {
        overlayList.push(command);
      } else {
        var commandNear;
        var commandFar;

        var boundingVolume = command.boundingVolume;
        if (defined(boundingVolume)) {
          if (!scene.isVisible(command, cullingVolume, occluder)) {
            continue;
          }

          var nearFarInterval = boundingVolume.computePlaneDistances(
            position,
            direction,
            scratchNearFarInterval
          );
          commandNear = nearFarInterval.start;
          commandFar = nearFarInterval.stop;
          near = Math.min(near, commandNear);
          far = Math.max(far, commandFar);

          // Compute a tight near and far plane for commands that receive shadows. This helps compute
          // good splits for cascaded shadow maps. Ignore commands that exceed the maximum distance.
          // When moving the camera low LOD globe tiles begin to load, whose bounding volumes
          // throw off the near/far fitting for the shadow map. Only update for globe tiles that the
          // camera isn't inside.
          if (
            shadowsEnabled &&
            command.receiveShadows &&
            commandNear < ShadowMap.MAXIMUM_DISTANCE &&
            !(pass === Pass$1.GLOBE && commandNear < -100.0 && commandFar > 100.0)
          ) {
            // Get the smallest bounding volume the camera is near. This is used to place more shadow detail near the object.
            var size = commandFar - commandNear;
            if (pass !== Pass$1.GLOBE && commandNear < 100.0) {
              shadowClosestObjectSize = Math.min(shadowClosestObjectSize, size);
            }
            shadowNear = Math.min(shadowNear, commandNear);
            shadowFar = Math.max(shadowFar, commandFar);
          }
        } else if (command instanceof ClearCommand) {
          // Clear commands don't need a bounding volume - just add the clear to all frustums.
          commandNear = camera.frustum.near;
          commandFar = camera.frustum.far;
        } else {
          // If command has no bounding volume we need to use the camera's
          // worst-case near and far planes to avoid clipping something important.
          commandNear = camera.frustum.near;
          commandFar = camera.frustum.far;
          near = Math.min(near, commandNear);
          far = Math.max(far, commandFar);
        }

        var extent = commandExtents[commandExtentCount];
        if (!defined(extent)) {
          extent = commandExtents[commandExtentCount] = new CommandExtent();
        }
        extent.command = command;
        extent.near = commandNear;
        extent.far = commandFar;
        commandExtentCount++;
      }
    }

    if (shadowsEnabled) {
      shadowNear = Math.min(
        Math.max(shadowNear, camera.frustum.near),
        camera.frustum.far
      );
      shadowFar = Math.max(Math.min(shadowFar, camera.frustum.far), shadowNear);
    }

    // Use the computed near and far for shadows
    if (shadowsEnabled) {
      frameState.shadowState.nearPlane = shadowNear;
      frameState.shadowState.farPlane = shadowFar;
      frameState.shadowState.closestObjectSize = shadowClosestObjectSize;
    }

    updateFrustums(this, scene, near, far);

    var c;
    var ce;

    for (c = 0; c < commandExtentCount; c++) {
      ce = commandExtents[c];
      insertIntoBin(this, scene, ce.command, ce.near, ce.far);
    }

    // Dereference old commands
    if (commandExtentCount < commandExtentCapacity) {
      for (c = commandExtentCount; c < commandExtentCapacity; c++) {
        ce = commandExtents[c];
        if (!defined(ce.command)) {
          // If the command is undefined, it's assumed that all
          // subsequent commmands were set to undefined as well,
          // so no need to loop over them all
          break;
        }
        ce.command = undefined;
      }
    }

    var numFrustums = frustumCommandsList.length;
    var frustumSplits = frameState.frustumSplits;
    frustumSplits.length = numFrustums + 1;
    for (var j = 0; j < numFrustums; ++j) {
      frustumSplits[j] = frustumCommandsList[j].near;
      if (j === numFrustums - 1) {
        frustumSplits[j + 1] = frustumCommandsList[j].far;
      }
    }
  };

  View.prototype.destroy = function () {
    this.pickFramebuffer = this.pickFramebuffer && this.pickFramebuffer.destroy();
    this.pickDepthFramebuffer =
      this.pickDepthFramebuffer && this.pickDepthFramebuffer.destroy();
    this.sceneFramebuffer =
      this.sceneFramebuffer && this.sceneFramebuffer.destroy();
    this.globeDepth = this.globeDepth && this.globeDepth.destroy();
    this.oit = this.oit && this.oit.destroy();
    this.globeTranslucencyFramebuffer =
      this.globeTranslucencyFramebuffer &&
      this.globeTranslucencyFramebuffer.destroy();

    var i;
    var length;

    var pickDepths = this.pickDepths;
    var debugGlobeDepths = this.debugGlobeDepths;

    length = pickDepths.length;
    for (i = 0; i < length; ++i) {
      pickDepths[i].destroy();
    }

    length = debugGlobeDepths.length;
    for (i = 0; i < length; ++i) {
      debugGlobeDepths[i].destroy();
    }
  };

  var offscreenDefaultWidth = 0.1;

  var mostDetailedPreloadTilesetPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.MOST_DETAILED_PRELOAD,
  });

  var mostDetailedPickTilesetPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.MOST_DETAILED_PICK,
  });

  var pickTilesetPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.PICK,
  });

  /**
   * @private
   */
  function Picking(scene) {
    this._mostDetailedRayPicks = [];
    this.pickRenderStateCache = {};
    this._pickPositionCache = {};
    this._pickPositionCacheDirty = false;

    var pickOffscreenViewport = new BoundingRectangle(0, 0, 1, 1);
    var pickOffscreenCamera = new Camera(scene);
    pickOffscreenCamera.frustum = new OrthographicFrustum({
      width: offscreenDefaultWidth,
      aspectRatio: 1.0,
      near: 0.1,
    });

    this._pickOffscreenView = new View(
      scene,
      pickOffscreenCamera,
      pickOffscreenViewport
    );
  }

  Picking.prototype.update = function () {
    this._pickPositionCacheDirty = true;
  };

  Picking.prototype.getPickDepth = function (scene, index) {
    var pickDepths = scene.view.pickDepths;
    var pickDepth = pickDepths[index];
    if (!defined(pickDepth)) {
      pickDepth = new PickDepth();
      pickDepths[index] = pickDepth;
    }
    return pickDepth;
  };

  var scratchOrthoPickingFrustum = new OrthographicOffCenterFrustum();
  var scratchOrthoOrigin = new Cartesian3();
  var scratchOrthoDirection = new Cartesian3();
  var scratchOrthoPixelSize = new Cartesian2();
  var scratchOrthoPickVolumeMatrix4 = new Matrix4();

  function getPickOrthographicCullingVolume(
    scene,
    drawingBufferPosition,
    width,
    height,
    viewport
  ) {
    var camera = scene.camera;
    var frustum = camera.frustum;
    if (defined(frustum._offCenterFrustum)) {
      frustum = frustum._offCenterFrustum;
    }

    var x = (2.0 * (drawingBufferPosition.x - viewport.x)) / viewport.width - 1.0;
    x *= (frustum.right - frustum.left) * 0.5;
    var y =
      (2.0 * (viewport.height - drawingBufferPosition.y - viewport.y)) /
        viewport.height -
      1.0;
    y *= (frustum.top - frustum.bottom) * 0.5;

    var transform = Matrix4.clone(
      camera.transform,
      scratchOrthoPickVolumeMatrix4
    );
    camera._setTransform(Matrix4.IDENTITY);

    var origin = Cartesian3.clone(camera.position, scratchOrthoOrigin);
    Cartesian3.multiplyByScalar(camera.right, x, scratchOrthoDirection);
    Cartesian3.add(scratchOrthoDirection, origin, origin);
    Cartesian3.multiplyByScalar(camera.up, y, scratchOrthoDirection);
    Cartesian3.add(scratchOrthoDirection, origin, origin);

    camera._setTransform(transform);

    if (scene.mode === SceneMode$1.SCENE2D) {
      Cartesian3.fromElements(origin.z, origin.x, origin.y, origin);
    }

    var pixelSize = frustum.getPixelDimensions(
      viewport.width,
      viewport.height,
      1.0,
      1.0,
      scratchOrthoPixelSize
    );

    var ortho = scratchOrthoPickingFrustum;
    ortho.right = pixelSize.x * 0.5;
    ortho.left = -ortho.right;
    ortho.top = pixelSize.y * 0.5;
    ortho.bottom = -ortho.top;
    ortho.near = frustum.near;
    ortho.far = frustum.far;

    return ortho.computeCullingVolume(origin, camera.directionWC, camera.upWC);
  }

  var scratchPerspPickingFrustum = new PerspectiveOffCenterFrustum();
  var scratchPerspPixelSize = new Cartesian2();

  function getPickPerspectiveCullingVolume(
    scene,
    drawingBufferPosition,
    width,
    height,
    viewport
  ) {
    var camera = scene.camera;
    var frustum = camera.frustum;
    var near = frustum.near;

    var tanPhi = Math.tan(frustum.fovy * 0.5);
    var tanTheta = frustum.aspectRatio * tanPhi;

    var x = (2.0 * (drawingBufferPosition.x - viewport.x)) / viewport.width - 1.0;
    var y =
      (2.0 * (viewport.height - drawingBufferPosition.y - viewport.y)) /
        viewport.height -
      1.0;

    var xDir = x * near * tanTheta;
    var yDir = y * near * tanPhi;

    var pixelSize = frustum.getPixelDimensions(
      viewport.width,
      viewport.height,
      1.0,
      1.0,
      scratchPerspPixelSize
    );
    var pickWidth = pixelSize.x * width * 0.5;
    var pickHeight = pixelSize.y * height * 0.5;

    var offCenter = scratchPerspPickingFrustum;
    offCenter.top = yDir + pickHeight;
    offCenter.bottom = yDir - pickHeight;
    offCenter.right = xDir + pickWidth;
    offCenter.left = xDir - pickWidth;
    offCenter.near = near;
    offCenter.far = frustum.far;

    return offCenter.computeCullingVolume(
      camera.positionWC,
      camera.directionWC,
      camera.upWC
    );
  }

  function getPickCullingVolume(
    scene,
    drawingBufferPosition,
    width,
    height,
    viewport
  ) {
    var frustum = scene.camera.frustum;
    if (
      frustum instanceof OrthographicFrustum ||
      frustum instanceof OrthographicOffCenterFrustum
    ) {
      return getPickOrthographicCullingVolume(
        scene,
        drawingBufferPosition,
        width,
        height,
        viewport
      );
    }

    return getPickPerspectiveCullingVolume(
      scene,
      drawingBufferPosition,
      width,
      height,
      viewport
    );
  }

  // pick rectangle width and height, assumed odd
  var scratchRectangleWidth = 3.0;
  var scratchRectangleHeight = 3.0;
  var scratchRectangle$7 = new BoundingRectangle(
    0.0,
    0.0,
    scratchRectangleWidth,
    scratchRectangleHeight
  );
  var scratchPosition$c = new Cartesian2();
  var scratchColorZero = new Color(0.0, 0.0, 0.0, 0.0);

  Picking.prototype.pick = function (scene, windowPosition, width, height) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(windowPosition)) {
      throw new DeveloperError("windowPosition is undefined.");
    }
    //>>includeEnd('debug');

    scratchRectangleWidth = defaultValue(width, 3.0);
    scratchRectangleHeight = defaultValue(height, scratchRectangleWidth);

    var context = scene.context;
    var us = context.uniformState;
    var frameState = scene.frameState;

    var view = scene.defaultView;
    scene.view = view;

    var viewport = view.viewport;
    viewport.x = 0;
    viewport.y = 0;
    viewport.width = context.drawingBufferWidth;
    viewport.height = context.drawingBufferHeight;

    var passState = view.passState;
    passState.viewport = BoundingRectangle.clone(viewport, passState.viewport);

    var drawingBufferPosition = SceneTransforms.transformWindowToDrawingBuffer(
      scene,
      windowPosition,
      scratchPosition$c
    );

    scene.jobScheduler.disableThisFrame();

    scene.updateFrameState();
    frameState.cullingVolume = getPickCullingVolume(
      scene,
      drawingBufferPosition,
      scratchRectangleWidth,
      scratchRectangleHeight,
      viewport
    );
    frameState.invertClassification = false;
    frameState.passes.pick = true;
    frameState.tilesetPassState = pickTilesetPassState;

    us.update(frameState);

    scene.updateEnvironment();

    scratchRectangle$7.x =
      drawingBufferPosition.x - (scratchRectangleWidth - 1.0) * 0.5;
    scratchRectangle$7.y =
      scene.drawingBufferHeight -
      drawingBufferPosition.y -
      (scratchRectangleHeight - 1.0) * 0.5;
    scratchRectangle$7.width = scratchRectangleWidth;
    scratchRectangle$7.height = scratchRectangleHeight;
    passState = view.pickFramebuffer.begin(scratchRectangle$7, view.viewport);

    scene.updateAndExecuteCommands(passState, scratchColorZero);
    scene.resolveFramebuffers(passState);

    var object = view.pickFramebuffer.end(scratchRectangle$7);
    context.endFrame();
    return object;
  };

  function renderTranslucentDepthForPick(scene, drawingBufferPosition) {
    // PERFORMANCE_IDEA: render translucent only and merge with the previous frame
    var context = scene.context;
    var frameState = scene.frameState;
    var environmentState = scene.environmentState;

    var view = scene.defaultView;
    scene.view = view;

    var viewport = view.viewport;
    viewport.x = 0;
    viewport.y = 0;
    viewport.width = context.drawingBufferWidth;
    viewport.height = context.drawingBufferHeight;

    var passState = view.passState;
    passState.viewport = BoundingRectangle.clone(viewport, passState.viewport);

    scene.clearPasses(frameState.passes);
    frameState.passes.pick = true;
    frameState.passes.depth = true;
    frameState.cullingVolume = getPickCullingVolume(
      scene,
      drawingBufferPosition,
      1,
      1,
      viewport
    );
    frameState.tilesetPassState = pickTilesetPassState;

    scene.updateEnvironment();
    environmentState.renderTranslucentDepthForPick = true;
    passState = view.pickDepthFramebuffer.update(
      context,
      drawingBufferPosition,
      viewport
    );

    scene.updateAndExecuteCommands(passState, scratchColorZero);
    scene.resolveFramebuffers(passState);

    context.endFrame();
  }

  var scratchPerspectiveFrustum = new PerspectiveFrustum();
  var scratchPerspectiveOffCenterFrustum = new PerspectiveOffCenterFrustum();
  var scratchOrthographicFrustum = new OrthographicFrustum();
  var scratchOrthographicOffCenterFrustum = new OrthographicOffCenterFrustum();

  Picking.prototype.pickPositionWorldCoordinates = function (
    scene,
    windowPosition,
    result
  ) {
    if (!scene.useDepthPicking) {
      return undefined;
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(windowPosition)) {
      throw new DeveloperError("windowPosition is undefined.");
    }
    if (!scene.context.depthTexture) {
      throw new DeveloperError(
        "Picking from the depth buffer is not supported. Check pickPositionSupported."
      );
    }
    //>>includeEnd('debug');

    var cacheKey = windowPosition.toString();

    if (this._pickPositionCacheDirty) {
      this._pickPositionCache = {};
      this._pickPositionCacheDirty = false;
    } else if (this._pickPositionCache.hasOwnProperty(cacheKey)) {
      return Cartesian3.clone(this._pickPositionCache[cacheKey], result);
    }

    var frameState = scene.frameState;
    var context = scene.context;
    var uniformState = context.uniformState;

    var view = scene.defaultView;
    scene.view = view;

    var drawingBufferPosition = SceneTransforms.transformWindowToDrawingBuffer(
      scene,
      windowPosition,
      scratchPosition$c
    );
    if (scene.pickTranslucentDepth) {
      renderTranslucentDepthForPick(scene, drawingBufferPosition);
    } else {
      scene.updateFrameState();
      uniformState.update(frameState);
      scene.updateEnvironment();
    }
    drawingBufferPosition.y = scene.drawingBufferHeight - drawingBufferPosition.y;

    var camera = scene.camera;

    // Create a working frustum from the original camera frustum.
    var frustum;
    if (defined(camera.frustum.fov)) {
      frustum = camera.frustum.clone(scratchPerspectiveFrustum);
    } else if (defined(camera.frustum.infiniteProjectionMatrix)) {
      frustum = camera.frustum.clone(scratchPerspectiveOffCenterFrustum);
    } else if (defined(camera.frustum.width)) {
      frustum = camera.frustum.clone(scratchOrthographicFrustum);
    } else {
      frustum = camera.frustum.clone(scratchOrthographicOffCenterFrustum);
    }

    var frustumCommandsList = view.frustumCommandsList;
    var numFrustums = frustumCommandsList.length;
    for (var i = 0; i < numFrustums; ++i) {
      var pickDepth = this.getPickDepth(scene, i);
      var depth = pickDepth.getDepth(
        context,
        drawingBufferPosition.x,
        drawingBufferPosition.y
      );
      if (!defined(depth)) {
        continue;
      }
      if (depth > 0.0 && depth < 1.0) {
        var renderedFrustum = frustumCommandsList[i];
        var height2D;
        if (scene.mode === SceneMode$1.SCENE2D) {
          height2D = camera.position.z;
          camera.position.z = height2D - renderedFrustum.near + 1.0;
          frustum.far = Math.max(1.0, renderedFrustum.far - renderedFrustum.near);
          frustum.near = 1.0;
          uniformState.update(frameState);
          uniformState.updateFrustum(frustum);
        } else {
          frustum.near =
            renderedFrustum.near *
            (i !== 0 ? scene.opaqueFrustumNearOffset : 1.0);
          frustum.far = renderedFrustum.far;
          uniformState.updateFrustum(frustum);
        }

        result = SceneTransforms.drawingBufferToWgs84Coordinates(
          scene,
          drawingBufferPosition,
          depth,
          result
        );

        if (scene.mode === SceneMode$1.SCENE2D) {
          camera.position.z = height2D;
          uniformState.update(frameState);
        }

        this._pickPositionCache[cacheKey] = Cartesian3.clone(result);
        return result;
      }
    }

    this._pickPositionCache[cacheKey] = undefined;
    return undefined;
  };

  var scratchPickPositionCartographic = new Cartographic();

  Picking.prototype.pickPosition = function (scene, windowPosition, result) {
    result = this.pickPositionWorldCoordinates(scene, windowPosition, result);
    if (defined(result) && scene.mode !== SceneMode$1.SCENE3D) {
      Cartesian3.fromElements(result.y, result.z, result.x, result);

      var projection = scene.mapProjection;
      var ellipsoid = projection.ellipsoid;

      var cart = projection.unproject(result, scratchPickPositionCartographic);
      ellipsoid.cartographicToCartesian(cart, result);
    }

    return result;
  };

  function drillPick(limit, pickCallback) {
    // PERFORMANCE_IDEA: This function calls each primitive's update for each pass. Instead
    // we could update the primitive once, and then just execute their commands for each pass,
    // and cull commands for picked primitives.  e.g., base on the command's owner.
    var i;
    var attributes;
    var result = [];
    var pickedPrimitives = [];
    var pickedAttributes = [];
    var pickedFeatures = [];
    if (!defined(limit)) {
      limit = Number.MAX_VALUE;
    }

    var pickedResult = pickCallback();
    while (defined(pickedResult)) {
      var object = pickedResult.object;
      var position = pickedResult.position;
      var exclude = pickedResult.exclude;

      if (defined(position) && !defined(object)) {
        result.push(pickedResult);
        break;
      }

      if (!defined(object) || !defined(object.primitive)) {
        break;
      }

      if (!exclude) {
        result.push(pickedResult);
        if (0 >= --limit) {
          break;
        }
      }

      var primitive = object.primitive;
      var hasShowAttribute = false;

      // If the picked object has a show attribute, use it.
      if (typeof primitive.getGeometryInstanceAttributes === "function") {
        if (defined(object.id)) {
          attributes = primitive.getGeometryInstanceAttributes(object.id);
          if (defined(attributes) && defined(attributes.show)) {
            hasShowAttribute = true;
            attributes.show = ShowGeometryInstanceAttribute.toValue(
              false,
              attributes.show
            );
            pickedAttributes.push(attributes);
          }
        }
      }

      if (object instanceof Cesium3DTileFeature) {
        hasShowAttribute = true;
        object.show = false;
        pickedFeatures.push(object);
      }

      // Otherwise, hide the entire primitive
      if (!hasShowAttribute) {
        primitive.show = false;
        pickedPrimitives.push(primitive);
      }

      pickedResult = pickCallback();
    }

    // Unhide everything we hid while drill picking
    for (i = 0; i < pickedPrimitives.length; ++i) {
      pickedPrimitives[i].show = true;
    }

    for (i = 0; i < pickedAttributes.length; ++i) {
      attributes = pickedAttributes[i];
      attributes.show = ShowGeometryInstanceAttribute.toValue(
        true,
        attributes.show
      );
    }

    for (i = 0; i < pickedFeatures.length; ++i) {
      pickedFeatures[i].show = true;
    }

    return result;
  }

  Picking.prototype.drillPick = function (
    scene,
    windowPosition,
    limit,
    width,
    height
  ) {
    var that = this;
    var pickCallback = function () {
      var object = that.pick(scene, windowPosition, width, height);
      if (defined(object)) {
        return {
          object: object,
          position: undefined,
          exclude: false,
        };
      }
    };
    var objects = drillPick(limit, pickCallback);
    return objects.map(function (element) {
      return element.object;
    });
  };

  var scratchRight$3 = new Cartesian3();
  var scratchUp$1 = new Cartesian3();

  function MostDetailedRayPick(ray, width, tilesets) {
    this.ray = ray;
    this.width = width;
    this.tilesets = tilesets;
    this.ready = false;
    this.deferred = when.defer();
    this.promise = this.deferred.promise;
  }

  function updateOffscreenCameraFromRay(picking, ray, width, camera) {
    var direction = ray.direction;
    var orthogonalAxis = Cartesian3.mostOrthogonalAxis(direction, scratchRight$3);
    var right = Cartesian3.cross(direction, orthogonalAxis, scratchRight$3);
    var up = Cartesian3.cross(direction, right, scratchUp$1);

    camera.position = ray.origin;
    camera.direction = direction;
    camera.up = up;
    camera.right = right;

    camera.frustum.width = defaultValue(width, offscreenDefaultWidth);
    return camera.frustum.computeCullingVolume(
      camera.positionWC,
      camera.directionWC,
      camera.upWC
    );
  }

  function updateMostDetailedRayPick(picking, scene, rayPick) {
    var frameState = scene.frameState;

    var ray = rayPick.ray;
    var width = rayPick.width;
    var tilesets = rayPick.tilesets;

    var camera = picking._pickOffscreenView.camera;
    var cullingVolume = updateOffscreenCameraFromRay(picking, ray, width, camera);

    var tilesetPassState = mostDetailedPreloadTilesetPassState;
    tilesetPassState.camera = camera;
    tilesetPassState.cullingVolume = cullingVolume;

    var ready = true;
    var tilesetsLength = tilesets.length;
    for (var i = 0; i < tilesetsLength; ++i) {
      var tileset = tilesets[i];
      if (tileset.show && scene.primitives.contains(tileset)) {
        // Only update tilesets that are still contained in the scene's primitive collection and are still visible
        // Update tilesets continually until all tilesets are ready. This way tiles are never removed from the cache.
        tileset.updateForPass(frameState, tilesetPassState);
        ready = ready && tilesetPassState.ready;
      }
    }

    if (ready) {
      rayPick.deferred.resolve();
    }

    return ready;
  }

  Picking.prototype.updateMostDetailedRayPicks = function (scene) {
    // Modifies array during iteration
    var rayPicks = this._mostDetailedRayPicks;
    for (var i = 0; i < rayPicks.length; ++i) {
      if (updateMostDetailedRayPick(this, scene, rayPicks[i])) {
        rayPicks.splice(i--, 1);
      }
    }
  };

  function getTilesets(primitives, objectsToExclude, tilesets) {
    var length = primitives.length;
    for (var i = 0; i < length; ++i) {
      var primitive = primitives.get(i);
      if (primitive.show) {
        if (defined(primitive.isCesium3DTileset)) {
          if (
            !defined(objectsToExclude) ||
            objectsToExclude.indexOf(primitive) === -1
          ) {
            tilesets.push(primitive);
          }
        } else if (primitive instanceof PrimitiveCollection) {
          getTilesets(primitive, objectsToExclude, tilesets);
        }
      }
    }
  }

  function launchMostDetailedRayPick(
    picking,
    scene,
    ray,
    objectsToExclude,
    width,
    callback
  ) {
    var tilesets = [];
    getTilesets(scene.primitives, objectsToExclude, tilesets);
    if (tilesets.length === 0) {
      return when.resolve(callback());
    }

    var rayPick = new MostDetailedRayPick(ray, width, tilesets);
    picking._mostDetailedRayPicks.push(rayPick);
    return rayPick.promise.then(function () {
      return callback();
    });
  }

  function isExcluded(object, objectsToExclude) {
    if (
      !defined(object) ||
      !defined(objectsToExclude) ||
      objectsToExclude.length === 0
    ) {
      return false;
    }
    return (
      objectsToExclude.indexOf(object) > -1 ||
      objectsToExclude.indexOf(object.primitive) > -1 ||
      objectsToExclude.indexOf(object.id) > -1
    );
  }

  function getRayIntersection(
    picking,
    scene,
    ray,
    objectsToExclude,
    width,
    requirePosition,
    mostDetailed
  ) {
    var context = scene.context;
    var uniformState = context.uniformState;
    var frameState = scene.frameState;

    var view = picking._pickOffscreenView;
    scene.view = view;

    updateOffscreenCameraFromRay(picking, ray, width, view.camera);

    scratchRectangle$7 = BoundingRectangle.clone(view.viewport, scratchRectangle$7);

    var passState = view.pickFramebuffer.begin(scratchRectangle$7, view.viewport);

    scene.jobScheduler.disableThisFrame();

    scene.updateFrameState();
    frameState.invertClassification = false;
    frameState.passes.pick = true;
    frameState.passes.offscreen = true;

    if (mostDetailed) {
      frameState.tilesetPassState = mostDetailedPickTilesetPassState;
    } else {
      frameState.tilesetPassState = pickTilesetPassState;
    }

    uniformState.update(frameState);

    scene.updateEnvironment();
    scene.updateAndExecuteCommands(passState, scratchColorZero);
    scene.resolveFramebuffers(passState);

    var position;
    var object = view.pickFramebuffer.end(context);

    if (scene.context.depthTexture) {
      var numFrustums = view.frustumCommandsList.length;
      for (var i = 0; i < numFrustums; ++i) {
        var pickDepth = picking.getPickDepth(scene, i);
        var depth = pickDepth.getDepth(context, 0, 0);
        if (!defined(depth)) {
          continue;
        }
        if (depth > 0.0 && depth < 1.0) {
          var renderedFrustum = view.frustumCommandsList[i];
          var near =
            renderedFrustum.near *
            (i !== 0 ? scene.opaqueFrustumNearOffset : 1.0);
          var far = renderedFrustum.far;
          var distance = near + depth * (far - near);
          position = Ray.getPoint(ray, distance);
          break;
        }
      }
    }

    scene.view = scene.defaultView;
    context.endFrame();

    if (defined(object) || defined(position)) {
      return {
        object: object,
        position: position,
        exclude:
          (!defined(position) && requirePosition) ||
          isExcluded(object, objectsToExclude),
      };
    }
  }

  function getRayIntersections(
    picking,
    scene,
    ray,
    limit,
    objectsToExclude,
    width,
    requirePosition,
    mostDetailed
  ) {
    var pickCallback = function () {
      return getRayIntersection(
        picking,
        scene,
        ray,
        objectsToExclude,
        width,
        requirePosition,
        mostDetailed
      );
    };
    return drillPick(limit, pickCallback);
  }

  function pickFromRay(
    picking,
    scene,
    ray,
    objectsToExclude,
    width,
    requirePosition,
    mostDetailed
  ) {
    var results = getRayIntersections(
      picking,
      scene,
      ray,
      1,
      objectsToExclude,
      width,
      requirePosition,
      mostDetailed
    );
    if (results.length > 0) {
      return results[0];
    }
  }

  function drillPickFromRay(
    picking,
    scene,
    ray,
    limit,
    objectsToExclude,
    width,
    requirePosition,
    mostDetailed
  ) {
    return getRayIntersections(
      picking,
      scene,
      ray,
      limit,
      objectsToExclude,
      width,
      requirePosition,
      mostDetailed
    );
  }

  function deferPromiseUntilPostRender(scene, promise) {
    // Resolve promise after scene's postRender in case entities are created when the promise resolves.
    // Entities can't be created between viewer._onTick and viewer._postRender.
    var deferred = when.defer();
    promise
      .then(function (result) {
        var removeCallback = scene.postRender.addEventListener(function () {
          deferred.resolve(result);
          removeCallback();
        });
        scene.requestRender();
      })
      .otherwise(function (error) {
        deferred.reject(error);
      });
    return deferred.promise;
  }

  Picking.prototype.pickFromRay = function (scene, ray, objectsToExclude, width) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("ray", ray);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError(
        "Ray intersections are only supported in 3D mode."
      );
    }
    //>>includeEnd('debug');

    return pickFromRay(this, scene, ray, objectsToExclude, width, false, false);
  };

  Picking.prototype.drillPickFromRay = function (
    scene,
    ray,
    limit,
    objectsToExclude,
    width
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("ray", ray);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError(
        "Ray intersections are only supported in 3D mode."
      );
    }
    //>>includeEnd('debug');

    return drillPickFromRay(
      this,
      scene,
      ray,
      limit,
      objectsToExclude,
      width,
      false,
      false
    );
  };

  Picking.prototype.pickFromRayMostDetailed = function (
    scene,
    ray,
    objectsToExclude,
    width
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("ray", ray);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError(
        "Ray intersections are only supported in 3D mode."
      );
    }
    //>>includeEnd('debug');

    var that = this;
    ray = Ray.clone(ray);
    objectsToExclude = defined(objectsToExclude)
      ? objectsToExclude.slice()
      : objectsToExclude;
    return deferPromiseUntilPostRender(
      scene,
      launchMostDetailedRayPick(
        that,
        scene,
        ray,
        objectsToExclude,
        width,
        function () {
          return pickFromRay(
            that,
            scene,
            ray,
            objectsToExclude,
            width,
            false,
            true
          );
        }
      )
    );
  };

  Picking.prototype.drillPickFromRayMostDetailed = function (
    scene,
    ray,
    limit,
    objectsToExclude,
    width
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("ray", ray);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError(
        "Ray intersections are only supported in 3D mode."
      );
    }
    //>>includeEnd('debug');

    var that = this;
    ray = Ray.clone(ray);
    objectsToExclude = defined(objectsToExclude)
      ? objectsToExclude.slice()
      : objectsToExclude;
    return deferPromiseUntilPostRender(
      scene,
      launchMostDetailedRayPick(
        that,
        scene,
        ray,
        objectsToExclude,
        width,
        function () {
          return drillPickFromRay(
            that,
            scene,
            ray,
            limit,
            objectsToExclude,
            width,
            false,
            true
          );
        }
      )
    );
  };

  var scratchSurfacePosition = new Cartesian3();
  var scratchSurfaceNormal = new Cartesian3();
  var scratchSurfaceRay = new Ray();
  var scratchCartographic$e = new Cartographic();

  function getRayForSampleHeight(scene, cartographic) {
    var globe = scene.globe;
    var ellipsoid = defined(globe)
      ? globe.ellipsoid
      : scene.mapProjection.ellipsoid;
    var height = ApproximateTerrainHeights._defaultMaxTerrainHeight;
    var surfaceNormal = ellipsoid.geodeticSurfaceNormalCartographic(
      cartographic,
      scratchSurfaceNormal
    );
    var surfacePosition = Cartographic.toCartesian(
      cartographic,
      ellipsoid,
      scratchSurfacePosition
    );
    var surfaceRay = scratchSurfaceRay;
    surfaceRay.origin = surfacePosition;
    surfaceRay.direction = surfaceNormal;
    var ray = new Ray();
    Ray.getPoint(surfaceRay, height, ray.origin);
    Cartesian3.negate(surfaceNormal, ray.direction);
    return ray;
  }

  function getRayForClampToHeight(scene, cartesian) {
    var globe = scene.globe;
    var ellipsoid = defined(globe)
      ? globe.ellipsoid
      : scene.mapProjection.ellipsoid;
    var cartographic = Cartographic.fromCartesian(
      cartesian,
      ellipsoid,
      scratchCartographic$e
    );
    return getRayForSampleHeight(scene, cartographic);
  }

  function getHeightFromCartesian(scene, cartesian) {
    var globe = scene.globe;
    var ellipsoid = defined(globe)
      ? globe.ellipsoid
      : scene.mapProjection.ellipsoid;
    var cartographic = Cartographic.fromCartesian(
      cartesian,
      ellipsoid,
      scratchCartographic$e
    );
    return cartographic.height;
  }

  function sampleHeightMostDetailed(
    picking,
    scene,
    cartographic,
    objectsToExclude,
    width
  ) {
    var ray = getRayForSampleHeight(scene, cartographic);
    return launchMostDetailedRayPick(
      picking,
      scene,
      ray,
      objectsToExclude,
      width,
      function () {
        var pickResult = pickFromRay(
          picking,
          scene,
          ray,
          objectsToExclude,
          width,
          true,
          true
        );
        if (defined(pickResult)) {
          return getHeightFromCartesian(scene, pickResult.position);
        }
      }
    );
  }

  function clampToHeightMostDetailed(
    picking,
    scene,
    cartesian,
    objectsToExclude,
    width,
    result
  ) {
    var ray = getRayForClampToHeight(scene, cartesian);
    return launchMostDetailedRayPick(
      picking,
      scene,
      ray,
      objectsToExclude,
      width,
      function () {
        var pickResult = pickFromRay(
          picking,
          scene,
          ray,
          objectsToExclude,
          width,
          true,
          true
        );
        if (defined(pickResult)) {
          return Cartesian3.clone(pickResult.position, result);
        }
      }
    );
  }

  Picking.prototype.sampleHeight = function (
    scene,
    position,
    objectsToExclude,
    width
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("position", position);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError("sampleHeight is only supported in 3D mode.");
    }
    if (!scene.sampleHeightSupported) {
      throw new DeveloperError(
        "sampleHeight requires depth texture support. Check sampleHeightSupported."
      );
    }
    //>>includeEnd('debug');

    var ray = getRayForSampleHeight(scene, position);
    var pickResult = pickFromRay(
      this,
      scene,
      ray,
      objectsToExclude,
      width,
      true,
      false
    );
    if (defined(pickResult)) {
      return getHeightFromCartesian(scene, pickResult.position);
    }
  };

  Picking.prototype.clampToHeight = function (
    scene,
    cartesian,
    objectsToExclude,
    width,
    result
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesian", cartesian);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError("clampToHeight is only supported in 3D mode.");
    }
    if (!scene.clampToHeightSupported) {
      throw new DeveloperError(
        "clampToHeight requires depth texture support. Check clampToHeightSupported."
      );
    }
    //>>includeEnd('debug');

    var ray = getRayForClampToHeight(scene, cartesian);
    var pickResult = pickFromRay(
      this,
      scene,
      ray,
      objectsToExclude,
      width,
      true,
      false
    );
    if (defined(pickResult)) {
      return Cartesian3.clone(pickResult.position, result);
    }
  };

  Picking.prototype.sampleHeightMostDetailed = function (
    scene,
    positions,
    objectsToExclude,
    width
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("positions", positions);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError(
        "sampleHeightMostDetailed is only supported in 3D mode."
      );
    }
    if (!scene.sampleHeightSupported) {
      throw new DeveloperError(
        "sampleHeightMostDetailed requires depth texture support. Check sampleHeightSupported."
      );
    }
    //>>includeEnd('debug');

    objectsToExclude = defined(objectsToExclude)
      ? objectsToExclude.slice()
      : objectsToExclude;
    var length = positions.length;
    var promises = new Array(length);
    for (var i = 0; i < length; ++i) {
      promises[i] = sampleHeightMostDetailed(
        this,
        scene,
        positions[i],
        objectsToExclude,
        width
      );
    }
    return deferPromiseUntilPostRender(
      scene,
      when.all(promises).then(function (heights) {
        var length = heights.length;
        for (var i = 0; i < length; ++i) {
          positions[i].height = heights[i];
        }
        return positions;
      })
    );
  };

  Picking.prototype.clampToHeightMostDetailed = function (
    scene,
    cartesians,
    objectsToExclude,
    width
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("cartesians", cartesians);
    if (scene.mode !== SceneMode$1.SCENE3D) {
      throw new DeveloperError(
        "clampToHeightMostDetailed is only supported in 3D mode."
      );
    }
    if (!scene.clampToHeightSupported) {
      throw new DeveloperError(
        "clampToHeightMostDetailed requires depth texture support. Check clampToHeightSupported."
      );
    }
    //>>includeEnd('debug');

    objectsToExclude = defined(objectsToExclude)
      ? objectsToExclude.slice()
      : objectsToExclude;
    var length = cartesians.length;
    var promises = new Array(length);
    for (var i = 0; i < length; ++i) {
      promises[i] = clampToHeightMostDetailed(
        this,
        scene,
        cartesians[i],
        objectsToExclude,
        width,
        cartesians[i]
      );
    }
    return deferPromiseUntilPostRender(
      scene,
      when.all(promises).then(function (clampedCartesians) {
        var length = clampedCartesians.length;
        for (var i = 0; i < length; ++i) {
          cartesians[i] = clampedCartesians[i];
        }
        return cartesians;
      })
    );
  };

  Picking.prototype.destroy = function () {
    this._pickOffscreenView =
      this._pickOffscreenView && this._pickOffscreenView.destroy();
  };

  /**
   * Determines how input texture to a {@link PostProcessStage} is sampled.
   *
   * @enum {Number}
   */
  var PostProcessStageSampleMode = {
    /**
     * Samples the texture by returning the closest texel.
     *
     * @type {Number}
     * @constant
     */
    NEAREST: 0,
    /**
     * Samples the texture through bi-linear interpolation of the four nearest texels.
     *
     * @type {Number}
     * @constant
     */
    LINEAR: 1,
  };

  /**
   * Runs a post-process stage on either the texture rendered by the scene or the output of a previous post-process stage.
   *
   * @alias PostProcessStage
   * @constructor
   *
   * @param {Object} options An object with the following properties:
   * @param {String} options.fragmentShader The fragment shader to use. The default <code>sampler2D</code> uniforms are <code>colorTexture</code> and <code>depthTexture</code>. The color texture is the output of rendering the scene or the previous stage. The depth texture is the output from rendering the scene. The shader should contain one or both uniforms. There is also a <code>vec2</code> varying named <code>v_textureCoordinates</code> that can be used to sample the textures.
   * @param {Object} [options.uniforms] An object whose properties will be used to set the shaders uniforms. The properties can be constant values or a function. A constant value can also be a URI, data URI, or HTML element to use as a texture.
   * @param {Number} [options.textureScale=1.0] A number in the range (0.0, 1.0] used to scale the texture dimensions. A scale of 1.0 will render this post-process stage  to a texture the size of the viewport.
   * @param {Boolean} [options.forcePowerOfTwo=false] Whether or not to force the texture dimensions to be both equal powers of two. The power of two will be the next power of two of the minimum of the dimensions.
   * @param {PostProcessStageSampleMode} [options.sampleMode=PostProcessStageSampleMode.NEAREST] How to sample the input color texture.
   * @param {PixelFormat} [options.pixelFormat=PixelFormat.RGBA] The color pixel format of the output texture.
   * @param {PixelDatatype} [options.pixelDatatype=PixelDatatype.UNSIGNED_BYTE] The pixel data type of the output texture.
   * @param {Color} [options.clearColor=Color.BLACK] The color to clear the output texture to.
   * @param {BoundingRectangle} [options.scissorRectangle] The rectangle to use for the scissor test.
   * @param {String} [options.name=createGuid()] The unique name of this post-process stage for reference by other stages in a composite. If a name is not supplied, a GUID will be generated.
   *
   * @exception {DeveloperError} options.textureScale must be greater than 0.0 and less than or equal to 1.0.
   * @exception {DeveloperError} options.pixelFormat must be a color format.
   * @exception {DeveloperError} When options.pixelDatatype is FLOAT, this WebGL implementation must support the OES_texture_float extension.  Check context.floatingPointTexture.
   *
   * @see PostProcessStageComposite
   *
   * @example
   * // Simple stage to change the color
   * var fs =
   *     'uniform sampler2D colorTexture;\n' +
   *     'varying vec2 v_textureCoordinates;\n' +
   *     'uniform float scale;\n' +
   *     'uniform vec3 offset;\n' +
   *     'void main() {\n' +
   *     '    vec4 color = texture2D(colorTexture, v_textureCoordinates);\n' +
   *     '    gl_FragColor = vec4(color.rgb * scale + offset, 1.0);\n' +
   *     '}\n';
   * scene.postProcessStages.add(new Cesium.PostProcessStage({
   *     fragmentShader : fs,
   *     uniforms : {
   *         scale : 1.1,
   *         offset : function() {
   *             return new Cesium.Cartesian3(0.1, 0.2, 0.3);
   *         }
   *     }
   * }));
   *
   * @example
   * // Simple stage to change the color of what is selected.
   * // If czm_selected returns true, the current fragment belongs to geometry in the selected array.
   * var fs =
   *     'uniform sampler2D colorTexture;\n' +
   *     'varying vec2 v_textureCoordinates;\n' +
   *     'uniform vec4 highlight;\n' +
   *     'void main() {\n' +
   *     '    vec4 color = texture2D(colorTexture, v_textureCoordinates);\n' +
   *     '    if (czm_selected()) {\n' +
   *     '        vec3 highlighted = highlight.a * highlight.rgb + (1.0 - highlight.a) * color.rgb;\n' +
   *     '        gl_FragColor = vec4(highlighted, 1.0);\n' +
   *     '    } else { \n' +
   *     '        gl_FragColor = color;\n' +
   *     '    }\n' +
   *     '}\n';
   * var stage = scene.postProcessStages.add(new Cesium.PostProcessStage({
   *     fragmentShader : fs,
   *     uniforms : {
   *         highlight : function() {
   *             return new Cesium.Color(1.0, 0.0, 0.0, 0.5);
   *         }
   *     }
   * }));
   * stage.selected = [cesium3DTileFeature];
   */
  function PostProcessStage(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var fragmentShader = options.fragmentShader;
    var textureScale = defaultValue(options.textureScale, 1.0);
    var pixelFormat = defaultValue(options.pixelFormat, PixelFormat$1.RGBA);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("options.fragmentShader", fragmentShader);
    Check.typeOf.number.greaterThan("options.textureScale", textureScale, 0.0);
    Check.typeOf.number.lessThanOrEquals(
      "options.textureScale",
      textureScale,
      1.0
    );
    if (!PixelFormat$1.isColorFormat(pixelFormat)) {
      throw new DeveloperError("options.pixelFormat must be a color format.");
    }
    //>>includeEnd('debug');

    this._fragmentShader = fragmentShader;
    this._uniforms = options.uniforms;
    this._textureScale = textureScale;
    this._forcePowerOfTwo = defaultValue(options.forcePowerOfTwo, false);
    this._sampleMode = defaultValue(
      options.sampleMode,
      PostProcessStageSampleMode.NEAREST
    );
    this._pixelFormat = pixelFormat;
    this._pixelDatatype = defaultValue(
      options.pixelDatatype,
      PixelDatatype$1.UNSIGNED_BYTE
    );
    this._clearColor = defaultValue(options.clearColor, Color.BLACK);

    this._uniformMap = undefined;
    this._command = undefined;

    this._colorTexture = undefined;
    this._depthTexture = undefined;
    this._idTexture = undefined;

    this._actualUniforms = {};
    this._dirtyUniforms = [];
    this._texturesToRelease = [];
    this._texturesToCreate = [];
    this._texturePromise = undefined;

    var passState = new PassState();
    passState.scissorTest = {
      enabled: true,
      rectangle: defined(options.scissorRectangle)
        ? BoundingRectangle.clone(options.scissorRectangle)
        : new BoundingRectangle(),
    };
    this._passState = passState;

    this._ready = false;

    var name = options.name;
    if (!defined(name)) {
      name = createGuid();
    }
    this._name = name;

    this._logDepthChanged = undefined;
    this._useLogDepth = undefined;

    this._selectedIdTexture = undefined;
    this._selected = undefined;
    this._selectedShadow = undefined;
    this._parentSelected = undefined;
    this._parentSelectedShadow = undefined;
    this._combinedSelected = undefined;
    this._combinedSelectedShadow = undefined;
    this._selectedLength = 0;
    this._parentSelectedLength = 0;
    this._selectedDirty = true;

    // set by PostProcessStageCollection
    this._textureCache = undefined;
    this._index = undefined;

    /**
     * Whether or not to execute this post-process stage when ready.
     *
     * @type {Boolean}
     */
    this.enabled = true;
    this._enabled = true;
  }

  Object.defineProperties(PostProcessStage.prototype, {
    /**
     * Determines if this post-process stage is ready to be executed. A stage is only executed when both <code>ready</code>
     * and {@link PostProcessStage#enabled} are <code>true</code>. A stage will not be ready while it is waiting on textures
     * to load.
     *
     * @memberof PostProcessStage.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return this._ready;
      },
    },
    /**
     * The unique name of this post-process stage for reference by other stages in a {@link PostProcessStageComposite}.
     *
     * @memberof PostProcessStage.prototype
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },
    /**
     * The fragment shader to use when execute this post-process stage.
     * <p>
     * The shader must contain a sampler uniform declaration for <code>colorTexture</code>, <code>depthTexture</code>,
     * or both.
     * </p>
     * <p>
     * The shader must contain a <code>vec2</code> varying declaration for <code>v_textureCoordinates</code> for sampling
     * the texture uniforms.
     * </p>
     *
     * @memberof PostProcessStage.prototype
     * @type {String}
     * @readonly
     */
    fragmentShader: {
      get: function () {
        return this._fragmentShader;
      },
    },
    /**
     * An object whose properties are used to set the uniforms of the fragment shader.
     * <p>
     * The object property values can be either a constant or a function. The function will be called
     * each frame before the post-process stage is executed.
     * </p>
     * <p>
     * A constant value can also be a URI to an image, a data URI, or an HTML element that can be used as a texture, such as HTMLImageElement or HTMLCanvasElement.
     * </p>
     * <p>
     * If this post-process stage is part of a {@link PostProcessStageComposite} that does not execute in series, the constant value can also be
     * the name of another stage in a composite. This will set the uniform to the output texture the stage with that name.
     * </p>
     *
     * @memberof PostProcessStage.prototype
     * @type {Object}
     * @readonly
     */
    uniforms: {
      get: function () {
        return this._uniforms;
      },
    },
    /**
     * A number in the range (0.0, 1.0] used to scale the output texture dimensions. A scale of 1.0 will render this post-process stage to a texture the size of the viewport.
     *
     * @memberof PostProcessStage.prototype
     * @type {Number}
     * @readonly
     */
    textureScale: {
      get: function () {
        return this._textureScale;
      },
    },
    /**
     * Whether or not to force the output texture dimensions to be both equal powers of two. The power of two will be the next power of two of the minimum of the dimensions.
     *
     * @memberof PostProcessStage.prototype
     * @type {Number}
     * @readonly
     */
    forcePowerOfTwo: {
      get: function () {
        return this._forcePowerOfTwo;
      },
    },
    /**
     * How to sample the input color texture.
     *
     * @memberof PostProcessStage.prototype
     * @type {PostProcessStageSampleMode}
     * @readonly
     */
    sampleMode: {
      get: function () {
        return this._sampleMode;
      },
    },
    /**
     * The color pixel format of the output texture.
     *
     * @memberof PostProcessStage.prototype
     * @type {PixelFormat}
     * @readonly
     */
    pixelFormat: {
      get: function () {
        return this._pixelFormat;
      },
    },
    /**
     * The pixel data type of the output texture.
     *
     * @memberof PostProcessStage.prototype
     * @type {PixelDatatype}
     * @readonly
     */
    pixelDatatype: {
      get: function () {
        return this._pixelDatatype;
      },
    },
    /**
     * The color to clear the output texture to.
     *
     * @memberof PostProcessStage.prototype
     * @type {Color}
     * @readonly
     */
    clearColor: {
      get: function () {
        return this._clearColor;
      },
    },
    /**
     * The {@link BoundingRectangle} to use for the scissor test. A default bounding rectangle will disable the scissor test.
     *
     * @memberof PostProcessStage.prototype
     * @type {BoundingRectangle}
     * @readonly
     */
    scissorRectangle: {
      get: function () {
        return this._passState.scissorTest.rectangle;
      },
    },
    /**
     * A reference to the texture written to when executing this post process stage.
     *
     * @memberof PostProcessStage.prototype
     * @type {Texture}
     * @readonly
     * @private
     */
    outputTexture: {
      get: function () {
        if (defined(this._textureCache)) {
          var framebuffer = this._textureCache.getFramebuffer(this._name);
          if (defined(framebuffer)) {
            return framebuffer.getColorTexture(0);
          }
        }
        return undefined;
      },
    },
    /**
     * The features selected for applying the post-process.
     * <p>
     * In the fragment shader, use <code>czm_selected</code> to determine whether or not to apply the post-process
     * stage to that fragment. For example:
     * <code>
     * if (czm_selected(v_textureCoordinates)) {
     *     // apply post-process stage
     * } else {
     *     gl_FragColor = texture2D(colorTexture, v_textureCordinates);
     * }
     * </code>
     * </p>
     *
     * @memberof PostProcessStage.prototype
     * @type {Array}
     */
    selected: {
      get: function () {
        return this._selected;
      },
      set: function (value) {
        this._selected = value;
      },
    },
    /**
     * @private
     */
    parentSelected: {
      get: function () {
        return this._parentSelected;
      },
      set: function (value) {
        this._parentSelected = value;
      },
    },
  });

  var depthTextureRegex = /uniform\s+sampler2D\s+depthTexture/g;

  /**
   * @private
   */
  PostProcessStage.prototype._isSupported = function (context) {
    return !depthTextureRegex.test(this._fragmentShader) || context.depthTexture;
  };

  function getUniformValueGetterAndSetter(stage, uniforms, name) {
    var currentValue = uniforms[name];
    if (
      typeof currentValue === "string" ||
      currentValue instanceof HTMLCanvasElement ||
      currentValue instanceof HTMLImageElement ||
      currentValue instanceof HTMLVideoElement ||
      currentValue instanceof ImageData
    ) {
      stage._dirtyUniforms.push(name);
    }

    return {
      get: function () {
        return uniforms[name];
      },
      set: function (value) {
        var currentValue = uniforms[name];
        uniforms[name] = value;

        var actualUniforms = stage._actualUniforms;
        var actualValue = actualUniforms[name];
        if (
          defined(actualValue) &&
          actualValue !== currentValue &&
          actualValue instanceof Texture &&
          !defined(stage._textureCache.getStageByName(name))
        ) {
          stage._texturesToRelease.push(actualValue);
          delete actualUniforms[name];
          delete actualUniforms[name + "Dimensions"];
        }

        if (currentValue instanceof Texture) {
          stage._texturesToRelease.push(currentValue);
        }

        if (
          typeof value === "string" ||
          value instanceof HTMLCanvasElement ||
          value instanceof HTMLImageElement ||
          value instanceof HTMLVideoElement ||
          value instanceof ImageData
        ) {
          stage._dirtyUniforms.push(name);
        } else {
          actualUniforms[name] = value;
        }
      },
    };
  }

  function getUniformMapFunction(stage, name) {
    return function () {
      var value = stage._actualUniforms[name];
      if (typeof value === "function") {
        return value();
      }
      return value;
    };
  }

  function getUniformMapDimensionsFunction(uniformMap, name) {
    return function () {
      var texture = uniformMap[name]();
      if (defined(texture)) {
        return texture.dimensions;
      }
      return undefined;
    };
  }

  function createUniformMap$5(stage) {
    if (defined(stage._uniformMap)) {
      return;
    }

    var uniformMap = {};
    var newUniforms = {};
    var uniforms = stage._uniforms;
    var actualUniforms = stage._actualUniforms;
    for (var name in uniforms) {
      if (uniforms.hasOwnProperty(name)) {
        if (typeof uniforms[name] !== "function") {
          uniformMap[name] = getUniformMapFunction(stage, name);
          newUniforms[name] = getUniformValueGetterAndSetter(
            stage,
            uniforms,
            name
          );
        } else {
          uniformMap[name] = uniforms[name];
          newUniforms[name] = uniforms[name];
        }

        actualUniforms[name] = uniforms[name];

        var value = uniformMap[name]();
        if (
          typeof value === "string" ||
          value instanceof Texture ||
          value instanceof HTMLImageElement ||
          value instanceof HTMLCanvasElement ||
          value instanceof HTMLVideoElement
        ) {
          uniformMap[name + "Dimensions"] = getUniformMapDimensionsFunction(
            uniformMap,
            name
          );
        }
      }
    }

    stage._uniforms = {};
    Object.defineProperties(stage._uniforms, newUniforms);

    stage._uniformMap = combine(uniformMap, {
      colorTexture: function () {
        return stage._colorTexture;
      },
      colorTextureDimensions: function () {
        return stage._colorTexture.dimensions;
      },
      depthTexture: function () {
        return stage._depthTexture;
      },
      depthTextureDimensions: function () {
        return stage._depthTexture.dimensions;
      },
      czm_idTexture: function () {
        return stage._idTexture;
      },
      czm_selectedIdTexture: function () {
        return stage._selectedIdTexture;
      },
      czm_selectedIdTextureStep: function () {
        return 1.0 / stage._selectedIdTexture.width;
      },
    });
  }

  function createDrawCommand(stage, context) {
    if (
      defined(stage._command) &&
      !stage._logDepthChanged &&
      !stage._selectedDirty
    ) {
      return;
    }

    var fs = stage._fragmentShader;
    if (defined(stage._selectedIdTexture)) {
      var width = stage._selectedIdTexture.width;

      fs = fs.replace(/varying\s+vec2\s+v_textureCoordinates;/g, "");
      fs =
        "#define CZM_SELECTED_FEATURE \n" +
        "uniform sampler2D czm_idTexture; \n" +
        "uniform sampler2D czm_selectedIdTexture; \n" +
        "uniform float czm_selectedIdTextureStep; \n" +
        "varying vec2 v_textureCoordinates; \n" +
        "bool czm_selected(vec2 offset) \n" +
        "{ \n" +
        "    bool selected = false;\n" +
        "    vec4 id = texture2D(czm_idTexture, v_textureCoordinates + offset); \n" +
        "    for (int i = 0; i < " +
        width +
        "; ++i) \n" +
        "    { \n" +
        "        vec4 selectedId = texture2D(czm_selectedIdTexture, vec2((float(i) + 0.5) * czm_selectedIdTextureStep, 0.5)); \n" +
        "        if (all(equal(id, selectedId))) \n" +
        "        { \n" +
        "            return true; \n" +
        "        } \n" +
        "    } \n" +
        "    return false; \n" +
        "} \n\n" +
        "bool czm_selected() \n" +
        "{ \n" +
        "    return czm_selected(vec2(0.0)); \n" +
        "} \n\n" +
        fs;
    }

    var fragmentShader = new ShaderSource({
      defines: [stage._useLogDepth ? "LOG_DEPTH" : ""],
      sources: [fs],
    });
    stage._command = context.createViewportQuadCommand(fragmentShader, {
      uniformMap: stage._uniformMap,
      owner: stage,
    });
  }

  function createSampler(stage) {
    var mode = stage._sampleMode;

    var minFilter;
    var magFilter;

    if (mode === PostProcessStageSampleMode.LINEAR) {
      minFilter = TextureMinificationFilter$1.LINEAR;
      magFilter = TextureMagnificationFilter$1.LINEAR;
    } else {
      minFilter = TextureMinificationFilter$1.NEAREST;
      magFilter = TextureMagnificationFilter$1.NEAREST;
    }

    var sampler = stage._sampler;
    if (
      !defined(sampler) ||
      sampler.minificationFilter !== minFilter ||
      sampler.magnificationFilter !== magFilter
    ) {
      stage._sampler = new Sampler({
        wrapS: TextureWrap$1.CLAMP_TO_EDGE,
        wrapT: TextureWrap$1.CLAMP_TO_EDGE,
        minificationFilter: minFilter,
        magnificationFilter: magFilter,
      });
    }
  }

  function createLoadImageFunction(stage, name) {
    return function (image) {
      stage._texturesToCreate.push({
        name: name,
        source: image,
      });
    };
  }

  function createStageOutputTextureFunction(stage, name) {
    return function () {
      return stage._textureCache.getOutputTexture(name);
    };
  }

  function updateUniformTextures(stage, context) {
    var i;
    var texture;
    var name;

    var texturesToRelease = stage._texturesToRelease;
    var length = texturesToRelease.length;
    for (i = 0; i < length; ++i) {
      texture = texturesToRelease[i];
      texture = texture && texture.destroy();
    }
    texturesToRelease.length = 0;

    var texturesToCreate = stage._texturesToCreate;
    length = texturesToCreate.length;
    for (i = 0; i < length; ++i) {
      var textureToCreate = texturesToCreate[i];
      name = textureToCreate.name;
      var source = textureToCreate.source;
      stage._actualUniforms[name] = new Texture({
        context: context,
        source: source,
      });
    }
    texturesToCreate.length = 0;

    var dirtyUniforms = stage._dirtyUniforms;
    if (dirtyUniforms.length === 0 && !defined(stage._texturePromise)) {
      stage._ready = true;
      return;
    }

    if (dirtyUniforms.length === 0 || defined(stage._texturePromise)) {
      return;
    }

    length = dirtyUniforms.length;
    var uniforms = stage._uniforms;
    var promises = [];
    for (i = 0; i < length; ++i) {
      name = dirtyUniforms[i];
      var stageNameUrlOrImage = uniforms[name];
      var stageWithName = stage._textureCache.getStageByName(stageNameUrlOrImage);
      if (defined(stageWithName)) {
        stage._actualUniforms[name] = createStageOutputTextureFunction(
          stage,
          stageNameUrlOrImage
        );
      } else if (typeof stageNameUrlOrImage === "string") {
        var resource = new Resource({
          url: stageNameUrlOrImage,
        });

        promises.push(
          resource.fetchImage().then(createLoadImageFunction(stage, name))
        );
      } else {
        stage._texturesToCreate.push({
          name: name,
          source: stageNameUrlOrImage,
        });
      }
    }

    dirtyUniforms.length = 0;

    if (promises.length > 0) {
      stage._ready = false;
      stage._texturePromise = when.all(promises).then(function () {
        stage._ready = true;
        stage._texturePromise = undefined;
      });
    } else {
      stage._ready = true;
    }
  }

  function releaseResources(stage) {
    if (defined(stage._command)) {
      stage._command.shaderProgram =
        stage._command.shaderProgram && stage._command.shaderProgram.destroy();
      stage._command = undefined;
    }

    stage._selectedIdTexture =
      stage._selectedIdTexture && stage._selectedIdTexture.destroy();

    var textureCache = stage._textureCache;
    if (!defined(textureCache)) {
      return;
    }

    var uniforms = stage._uniforms;
    var actualUniforms = stage._actualUniforms;
    for (var name in actualUniforms) {
      if (actualUniforms.hasOwnProperty(name)) {
        if (actualUniforms[name] instanceof Texture) {
          if (!defined(textureCache.getStageByName(uniforms[name]))) {
            actualUniforms[name].destroy();
          }
          stage._dirtyUniforms.push(name);
        }
      }
    }
  }

  function isSelectedTextureDirty(stage) {
    var length = defined(stage._selected) ? stage._selected.length : 0;
    var parentLength = defined(stage._parentSelected) ? stage._parentSelected : 0;
    var dirty =
      stage._selected !== stage._selectedShadow ||
      length !== stage._selectedLength;
    dirty =
      dirty ||
      stage._parentSelected !== stage._parentSelectedShadow ||
      parentLength !== stage._parentSelectedLength;

    if (defined(stage._selected) && defined(stage._parentSelected)) {
      stage._combinedSelected = stage._selected.concat(stage._parentSelected);
    } else if (defined(stage._parentSelected)) {
      stage._combinedSelected = stage._parentSelected;
    } else {
      stage._combinedSelected = stage._selected;
    }

    if (!dirty && defined(stage._combinedSelected)) {
      if (!defined(stage._combinedSelectedShadow)) {
        return true;
      }

      length = stage._combinedSelected.length;
      for (var i = 0; i < length; ++i) {
        if (stage._combinedSelected[i] !== stage._combinedSelectedShadow[i]) {
          return true;
        }
      }
    }
    return dirty;
  }

  function createSelectedTexture(stage, context) {
    if (!stage._selectedDirty) {
      return;
    }

    stage._selectedIdTexture =
      stage._selectedIdTexture && stage._selectedIdTexture.destroy();
    stage._selectedIdTexture = undefined;

    var features = stage._combinedSelected;
    if (!defined(features)) {
      return;
    }

    var i;
    var feature;

    var textureLength = 0;
    var length = features.length;
    for (i = 0; i < length; ++i) {
      feature = features[i];
      if (defined(feature.pickIds)) {
        textureLength += feature.pickIds.length;
      } else if (defined(feature.pickId)) {
        ++textureLength;
      }
    }

    if (length === 0 || textureLength === 0) {
      // max pick id is reserved
      var empty = new Uint8Array(4);
      empty[0] = 255;
      empty[1] = 255;
      empty[2] = 255;
      empty[3] = 255;

      stage._selectedIdTexture = new Texture({
        context: context,
        pixelFormat: PixelFormat$1.RGBA,
        pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
        source: {
          arrayBufferView: empty,
          width: 1,
          height: 1,
        },
        sampler: Sampler.NEAREST,
      });
      return;
    }

    var pickColor;
    var offset = 0;
    var ids = new Uint8Array(textureLength * 4);
    for (i = 0; i < length; ++i) {
      feature = features[i];
      if (defined(feature.pickIds)) {
        var pickIds = feature.pickIds;
        var pickIdsLength = pickIds.length;
        for (var j = 0; j < pickIdsLength; ++j) {
          pickColor = pickIds[j].color;
          ids[offset] = Color.floatToByte(pickColor.red);
          ids[offset + 1] = Color.floatToByte(pickColor.green);
          ids[offset + 2] = Color.floatToByte(pickColor.blue);
          ids[offset + 3] = Color.floatToByte(pickColor.alpha);
          offset += 4;
        }
      } else if (defined(feature.pickId)) {
        pickColor = feature.pickId.color;
        ids[offset] = Color.floatToByte(pickColor.red);
        ids[offset + 1] = Color.floatToByte(pickColor.green);
        ids[offset + 2] = Color.floatToByte(pickColor.blue);
        ids[offset + 3] = Color.floatToByte(pickColor.alpha);
        offset += 4;
      }
    }

    stage._selectedIdTexture = new Texture({
      context: context,
      pixelFormat: PixelFormat$1.RGBA,
      pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
      source: {
        arrayBufferView: ids,
        width: textureLength,
        height: 1,
      },
      sampler: Sampler.NEAREST,
    });
  }

  /**
   * A function that will be called before execute. Used to create WebGL resources and load any textures.
   * @param {Context} context The context.
   * @param {Boolean} useLogDepth Whether the scene uses a logarithmic depth buffer.
   * @private
   */
  PostProcessStage.prototype.update = function (context, useLogDepth) {
    if (this.enabled !== this._enabled && !this.enabled) {
      releaseResources(this);
    }

    this._enabled = this.enabled;
    if (!this._enabled) {
      return;
    }

    this._logDepthChanged = useLogDepth !== this._useLogDepth;
    this._useLogDepth = useLogDepth;

    this._selectedDirty = isSelectedTextureDirty(this);

    this._selectedShadow = this._selected;
    this._parentSelectedShadow = this._parentSelected;
    this._combinedSelectedShadow = this._combinedSelected;
    this._selectedLength = defined(this._selected) ? this._selected.length : 0;
    this._parentSelectedLength = defined(this._parentSelected)
      ? this._parentSelected.length
      : 0;

    createSelectedTexture(this, context);
    createUniformMap$5(this);
    updateUniformTextures(this, context);
    createDrawCommand(this, context);
    createSampler(this);

    this._selectedDirty = false;

    if (!this._ready) {
      return;
    }

    var framebuffer = this._textureCache.getFramebuffer(this._name);
    this._command.framebuffer = framebuffer;

    if (!defined(framebuffer)) {
      return;
    }

    var colorTexture = framebuffer.getColorTexture(0);
    var renderState;
    if (
      colorTexture.width !== context.drawingBufferWidth ||
      colorTexture.height !== context.drawingBufferHeight
    ) {
      renderState = this._renderState;
      if (
        !defined(renderState) ||
        colorTexture.width !== renderState.viewport.width ||
        colorTexture.height !== renderState.viewport.height
      ) {
        this._renderState = RenderState.fromCache({
          viewport: new BoundingRectangle(
            0,
            0,
            colorTexture.width,
            colorTexture.height
          ),
        });
      }
    }

    this._command.renderState = renderState;
  };

  /**
   * Executes the post-process stage. The color texture is the texture rendered to by the scene or from the previous stage.
   * @param {Context} context The context.
   * @param {Texture} colorTexture The input color texture.
   * @param {Texture} depthTexture The input depth texture.
   * @param {Texture} idTexture The id texture.
   * @private
   */
  PostProcessStage.prototype.execute = function (
    context,
    colorTexture,
    depthTexture,
    idTexture
  ) {
    if (
      !defined(this._command) ||
      !defined(this._command.framebuffer) ||
      !this._ready ||
      !this._enabled
    ) {
      return;
    }

    this._colorTexture = colorTexture;
    this._depthTexture = depthTexture;
    this._idTexture = idTexture;

    if (!Sampler.equals(this._colorTexture.sampler, this._sampler)) {
      this._colorTexture.sampler = this._sampler;
    }

    var passState =
      this.scissorRectangle.width > 0 && this.scissorRectangle.height > 0
        ? this._passState
        : undefined;
    if (defined(passState)) {
      passState.context = context;
    }

    this._command.execute(context, passState);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PostProcessStage#destroy
   */
  PostProcessStage.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PostProcessStage#isDestroyed
   */
  PostProcessStage.prototype.destroy = function () {
    releaseResources(this);
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var AcesTonemapping = "uniform sampler2D colorTexture;\n\
varying vec2 v_textureCoordinates;\n\
#ifdef AUTO_EXPOSURE\n\
uniform sampler2D autoExposure;\n\
#endif\n\
void main()\n\
{\n\
vec4 fragmentColor = texture2D(colorTexture, v_textureCoordinates);\n\
vec3 color = fragmentColor.rgb;\n\
#ifdef AUTO_EXPOSURE\n\
color /= texture2D(autoExposure, vec2(0.5)).r;\n\
#endif\n\
color = czm_acesTonemapping(color);\n\
color = czm_inverseGamma(color);\n\
gl_FragColor = vec4(color, fragmentColor.a);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var AmbientOcclusionGenerate = "uniform sampler2D randomTexture;\n\
uniform sampler2D depthTexture;\n\
uniform float intensity;\n\
uniform float bias;\n\
uniform float lengthCap;\n\
uniform float stepSize;\n\
uniform float frustumLength;\n\
varying vec2 v_textureCoordinates;\n\
vec4 clipToEye(vec2 uv, float depth)\n\
{\n\
vec2 xy = vec2((uv.x * 2.0 - 1.0), ((1.0 - uv.y) * 2.0 - 1.0));\n\
vec4 posEC = czm_inverseProjection * vec4(xy, depth, 1.0);\n\
posEC = posEC / posEC.w;\n\
return posEC;\n\
}\n\
vec3 getNormalXEdge(vec3 posInCamera, float depthU, float depthD, float depthL, float depthR, vec2 pixelSize)\n\
{\n\
vec4 posInCameraUp = clipToEye(v_textureCoordinates - vec2(0.0, pixelSize.y), depthU);\n\
vec4 posInCameraDown = clipToEye(v_textureCoordinates + vec2(0.0, pixelSize.y), depthD);\n\
vec4 posInCameraLeft = clipToEye(v_textureCoordinates - vec2(pixelSize.x, 0.0), depthL);\n\
vec4 posInCameraRight = clipToEye(v_textureCoordinates + vec2(pixelSize.x, 0.0), depthR);\n\
vec3 up = posInCamera.xyz - posInCameraUp.xyz;\n\
vec3 down = posInCameraDown.xyz - posInCamera.xyz;\n\
vec3 left = posInCamera.xyz - posInCameraLeft.xyz;\n\
vec3 right = posInCameraRight.xyz - posInCamera.xyz;\n\
vec3 DX = length(left) < length(right) ? left : right;\n\
vec3 DY = length(up) < length(down) ? up : down;\n\
return normalize(cross(DY, DX));\n\
}\n\
void main(void)\n\
{\n\
float depth = czm_readDepth(depthTexture, v_textureCoordinates);\n\
vec4 posInCamera = clipToEye(v_textureCoordinates, depth);\n\
if (posInCamera.z > frustumLength)\n\
{\n\
gl_FragColor = vec4(1.0);\n\
return;\n\
}\n\
vec2 pixelSize = czm_pixelRatio / czm_viewport.zw;\n\
float depthU = czm_readDepth(depthTexture, v_textureCoordinates - vec2(0.0, pixelSize.y));\n\
float depthD = czm_readDepth(depthTexture, v_textureCoordinates + vec2(0.0, pixelSize.y));\n\
float depthL = czm_readDepth(depthTexture, v_textureCoordinates - vec2(pixelSize.x, 0.0));\n\
float depthR = czm_readDepth(depthTexture, v_textureCoordinates + vec2(pixelSize.x, 0.0));\n\
vec3 normalInCamera = getNormalXEdge(posInCamera.xyz, depthU, depthD, depthL, depthR, pixelSize);\n\
float ao = 0.0;\n\
vec2 sampleDirection = vec2(1.0, 0.0);\n\
float gapAngle = 90.0 * czm_radiansPerDegree;\n\
float randomVal = texture2D(randomTexture, v_textureCoordinates).x;\n\
for (int i = 0; i < 4; i++)\n\
{\n\
float newGapAngle = gapAngle * (float(i) + randomVal);\n\
float cosVal = cos(newGapAngle);\n\
float sinVal = sin(newGapAngle);\n\
vec2 rotatedSampleDirection = vec2(cosVal * sampleDirection.x - sinVal * sampleDirection.y, sinVal * sampleDirection.x + cosVal * sampleDirection.y);\n\
float localAO = 0.0;\n\
float localStepSize = stepSize;\n\
for (int j = 0; j < 6; j++)\n\
{\n\
vec2 newCoords = v_textureCoordinates + rotatedSampleDirection * localStepSize * pixelSize;\n\
if(newCoords.x > 1.0 || newCoords.y > 1.0 || newCoords.x < 0.0 || newCoords.y < 0.0)\n\
{\n\
break;\n\
}\n\
float stepDepthInfo = czm_readDepth(depthTexture, newCoords);\n\
vec4 stepPosInCamera = clipToEye(newCoords, stepDepthInfo);\n\
vec3 diffVec = stepPosInCamera.xyz - posInCamera.xyz;\n\
float len = length(diffVec);\n\
if (len > lengthCap)\n\
{\n\
break;\n\
}\n\
float dotVal = clamp(dot(normalInCamera, normalize(diffVec)), 0.0, 1.0 );\n\
float weight = len / lengthCap;\n\
weight = 1.0 - weight * weight;\n\
if (dotVal < bias)\n\
{\n\
dotVal = 0.0;\n\
}\n\
localAO = max(localAO, dotVal * weight);\n\
localStepSize += stepSize;\n\
}\n\
ao += localAO;\n\
}\n\
ao /= 4.0;\n\
ao = 1.0 - clamp(ao, 0.0, 1.0);\n\
ao = pow(ao, intensity);\n\
gl_FragColor = vec4(vec3(ao), 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var AmbientOcclusionModulate = "uniform sampler2D colorTexture;\n\
uniform sampler2D ambientOcclusionTexture;\n\
uniform bool ambientOcclusionOnly;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
vec3 color = texture2D(colorTexture, v_textureCoordinates).rgb;\n\
vec3 ao = texture2D(ambientOcclusionTexture, v_textureCoordinates).rgb;\n\
gl_FragColor.rgb = ambientOcclusionOnly ? ao : ao * color;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BlackAndWhite = "uniform sampler2D colorTexture;\n\
uniform float gradations;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
vec3 rgb = texture2D(colorTexture, v_textureCoordinates).rgb;\n\
#ifdef CZM_SELECTED_FEATURE\n\
if (czm_selected()) {\n\
gl_FragColor = vec4(rgb, 1.0);\n\
return;\n\
}\n\
#endif\n\
float luminance = czm_luminance(rgb);\n\
float darkness = luminance * gradations;\n\
darkness = (darkness - fract(darkness)) / gradations;\n\
gl_FragColor = vec4(vec3(darkness), 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BloomComposite = "uniform sampler2D colorTexture;\n\
uniform sampler2D bloomTexture;\n\
uniform bool glowOnly;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
vec4 color = texture2D(colorTexture, v_textureCoordinates);\n\
#ifdef CZM_SELECTED_FEATURE\n\
if (czm_selected()) {\n\
gl_FragColor = color;\n\
return;\n\
}\n\
#endif\n\
vec4 bloom = texture2D(bloomTexture, v_textureCoordinates);\n\
gl_FragColor = glowOnly ? bloom : bloom + color;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var Brightness = "uniform sampler2D colorTexture;\n\
uniform float brightness;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
vec3 rgb = texture2D(colorTexture, v_textureCoordinates).rgb;\n\
vec3 target = vec3(0.0);\n\
gl_FragColor = vec4(mix(target, rgb, brightness), 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ContrastBias = "uniform sampler2D colorTexture;\n\
uniform float contrast;\n\
uniform float brightness;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
vec3 sceneColor = texture2D(colorTexture, v_textureCoordinates).xyz;\n\
sceneColor = czm_RGBToHSB(sceneColor);\n\
sceneColor.z += brightness;\n\
sceneColor = czm_HSBToRGB(sceneColor);\n\
float factor = (259.0 * (contrast + 255.0)) / (255.0 * (259.0 - contrast));\n\
sceneColor = factor * (sceneColor - vec3(0.5)) + vec3(0.5);\n\
gl_FragColor = vec4(sceneColor, 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var DepthOfField = "uniform sampler2D colorTexture;\n\
uniform sampler2D blurTexture;\n\
uniform sampler2D depthTexture;\n\
uniform float focalDistance;\n\
varying vec2 v_textureCoordinates;\n\
vec4 toEye(vec2 uv, float depth)\n\
{\n\
vec2 xy = vec2((uv.x * 2.0 - 1.0), ((1.0 - uv.y) * 2.0 - 1.0));\n\
vec4 posInCamera = czm_inverseProjection * vec4(xy, depth, 1.0);\n\
posInCamera = posInCamera / posInCamera.w;\n\
return posInCamera;\n\
}\n\
float computeDepthBlur(float depth)\n\
{\n\
float f;\n\
if (depth < focalDistance)\n\
{\n\
f = (focalDistance - depth) / (focalDistance - czm_currentFrustum.x);\n\
}\n\
else\n\
{\n\
f = (depth - focalDistance) / (czm_currentFrustum.y - focalDistance);\n\
f = pow(f, 0.1);\n\
}\n\
f *= f;\n\
f = clamp(f, 0.0, 1.0);\n\
return pow(f, 0.5);\n\
}\n\
void main(void)\n\
{\n\
float depth = czm_readDepth(depthTexture, v_textureCoordinates);\n\
vec4 posInCamera = toEye(v_textureCoordinates, depth);\n\
float d = computeDepthBlur(-posInCamera.z);\n\
gl_FragColor = mix(texture2D(colorTexture, v_textureCoordinates), texture2D(blurTexture, v_textureCoordinates), d);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var DepthView = "uniform sampler2D depthTexture;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
float depth = czm_readDepth(depthTexture, v_textureCoordinates);\n\
gl_FragColor = vec4(vec3(depth), 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var EdgeDetection = "uniform sampler2D depthTexture;\n\
uniform float length;\n\
uniform vec4 color;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
float directions[3];\n\
directions[0] = -1.0;\n\
directions[1] = 0.0;\n\
directions[2] = 1.0;\n\
float scalars[3];\n\
scalars[0] = 3.0;\n\
scalars[1] = 10.0;\n\
scalars[2] = 3.0;\n\
float padx = czm_pixelRatio / czm_viewport.z;\n\
float pady = czm_pixelRatio / czm_viewport.w;\n\
#ifdef CZM_SELECTED_FEATURE\n\
bool selected = false;\n\
for (int i = 0; i < 3; ++i)\n\
{\n\
float dir = directions[i];\n\
selected = selected || czm_selected(vec2(-padx, dir * pady));\n\
selected = selected || czm_selected(vec2(padx, dir * pady));\n\
selected = selected || czm_selected(vec2(dir * padx, -pady));\n\
selected = selected || czm_selected(vec2(dir * padx, pady));\n\
if (selected)\n\
{\n\
break;\n\
}\n\
}\n\
if (!selected)\n\
{\n\
gl_FragColor = vec4(color.rgb, 0.0);\n\
return;\n\
}\n\
#endif\n\
float horizEdge = 0.0;\n\
float vertEdge = 0.0;\n\
for (int i = 0; i < 3; ++i)\n\
{\n\
float dir = directions[i];\n\
float scale = scalars[i];\n\
horizEdge -= texture2D(depthTexture, v_textureCoordinates + vec2(-padx, dir * pady)).x * scale;\n\
horizEdge += texture2D(depthTexture, v_textureCoordinates + vec2(padx, dir * pady)).x * scale;\n\
vertEdge -= texture2D(depthTexture, v_textureCoordinates + vec2(dir * padx, -pady)).x * scale;\n\
vertEdge += texture2D(depthTexture, v_textureCoordinates + vec2(dir * padx, pady)).x * scale;\n\
}\n\
float len = sqrt(horizEdge * horizEdge + vertEdge * vertEdge);\n\
gl_FragColor = vec4(color.rgb, len > length ? color.a : 0.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var FilmicTonemapping = "uniform sampler2D colorTexture;\n\
varying vec2 v_textureCoordinates;\n\
#ifdef AUTO_EXPOSURE\n\
uniform sampler2D autoExposure;\n\
#endif\n\
void main()\n\
{\n\
vec4 fragmentColor = texture2D(colorTexture, v_textureCoordinates);\n\
vec3 color = fragmentColor.rgb;\n\
#ifdef AUTO_EXPOSURE\n\
float exposure = texture2D(autoExposure, vec2(0.5)).r;\n\
color /= exposure;\n\
#endif\n\
const float A = 0.22;\n\
const float B = 0.30;\n\
const float C = 0.10;\n\
const float D = 0.20;\n\
const float E = 0.01;\n\
const float F = 0.30;\n\
const float white = 11.2;\n\
vec3 c = ((color * (A * color + C * B) + D * E) / (color * ( A * color + B) + D * F)) - E / F;\n\
float w = ((white * (A * white + C * B) + D * E) / (white * ( A * white + B) + D * F)) - E / F;\n\
c = czm_inverseGamma(c / w);\n\
gl_FragColor = vec4(c, fragmentColor.a);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var FXAA = "varying vec2 v_textureCoordinates;\n\
uniform sampler2D colorTexture;\n\
const float fxaaQualitySubpix = 0.5;\n\
const float fxaaQualityEdgeThreshold = 0.125;\n\
const float fxaaQualityEdgeThresholdMin = 0.0833;\n\
void main()\n\
{\n\
vec2 fxaaQualityRcpFrame = vec2(1.0) / czm_viewport.zw;\n\
vec4 color = FxaaPixelShader(\n\
v_textureCoordinates,\n\
colorTexture,\n\
fxaaQualityRcpFrame,\n\
fxaaQualitySubpix,\n\
fxaaQualityEdgeThreshold,\n\
fxaaQualityEdgeThresholdMin);\n\
float alpha = texture2D(colorTexture, v_textureCoordinates).a;\n\
gl_FragColor = vec4(color.rgb, alpha);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var GaussianBlur1D = "#define SAMPLES 8\n\
uniform float delta;\n\
uniform float sigma;\n\
uniform float direction;\n\
uniform sampler2D colorTexture;\n\
#ifdef USE_STEP_SIZE\n\
uniform float stepSize;\n\
#else\n\
uniform vec2 step;\n\
#endif\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
vec2 st = v_textureCoordinates;\n\
vec2 dir = vec2(1.0 - direction, direction);\n\
#ifdef USE_STEP_SIZE\n\
vec2 step = vec2(stepSize * (czm_pixelRatio / czm_viewport.zw));\n\
#else\n\
vec2 step = step;\n\
#endif\n\
vec3 g;\n\
g.x = 1.0 / (sqrt(czm_twoPi) * sigma);\n\
g.y = exp((-0.5 * delta * delta) / (sigma * sigma));\n\
g.z = g.y * g.y;\n\
vec4 result = texture2D(colorTexture, st) * g.x;\n\
for (int i = 1; i < SAMPLES; ++i)\n\
{\n\
g.xy *= g.yz;\n\
vec2 offset = float(i) * dir * step;\n\
result += texture2D(colorTexture, st - offset) * g.x;\n\
result += texture2D(colorTexture, st + offset) * g.x;\n\
}\n\
gl_FragColor = result;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var LensFlare = "uniform sampler2D colorTexture;\n\
uniform sampler2D dirtTexture;\n\
uniform sampler2D starTexture;\n\
uniform vec2 dirtTextureDimensions;\n\
uniform float distortion;\n\
uniform float ghostDispersal;\n\
uniform float haloWidth;\n\
uniform float dirtAmount;\n\
uniform float earthRadius;\n\
uniform float intensity;\n\
varying vec2 v_textureCoordinates;\n\
#define DISTANCE_TO_SPACE 6500000.0\n\
vec4 getNDCFromWC(vec3 WC, float earthRadius)\n\
{\n\
vec4 positionEC = czm_view * vec4(WC, 1.0);\n\
positionEC = vec4(positionEC.x + earthRadius, positionEC.y, positionEC.z, 1.0);\n\
vec4 positionWC = czm_eyeToWindowCoordinates(positionEC);\n\
return czm_viewportOrthographic * vec4(positionWC.xy, -positionWC.z, 1.0);\n\
}\n\
float isInEarth(vec2 texcoord, vec2 sceneSize)\n\
{\n\
vec2 NDC = texcoord * 2.0 - 1.0;\n\
vec4 earthPosSC = getNDCFromWC(vec3(0.0), 0.0);\n\
vec4 earthPosSCEdge = getNDCFromWC(vec3(0.0), earthRadius * 1.5);\n\
NDC.xy -= earthPosSC.xy;\n\
float X = abs(NDC.x) * sceneSize.x;\n\
float Y = abs(NDC.y) * sceneSize.y;\n\
return clamp(0.0, 1.0, max(sqrt(X * X + Y * Y) / max(abs(earthPosSCEdge.x * sceneSize.x), 1.0) - 0.8 , 0.0));\n\
}\n\
vec4 textureDistorted(sampler2D tex, vec2 texcoord, vec2 direction, vec3 distortion, bool isSpace)\n\
{\n\
vec2 sceneSize = czm_viewport.zw;\n\
vec3 color;\n\
if(isSpace)\n\
{\n\
color.r = isInEarth(texcoord + direction * distortion.r, sceneSize) * texture2D(tex, texcoord + direction * distortion.r).r;\n\
color.g = isInEarth(texcoord + direction * distortion.g, sceneSize) * texture2D(tex, texcoord + direction * distortion.g).g;\n\
color.b = isInEarth(texcoord + direction * distortion.b, sceneSize) * texture2D(tex, texcoord + direction * distortion.b).b;\n\
}\n\
else\n\
{\n\
color.r = texture2D(tex, texcoord + direction * distortion.r).r;\n\
color.g = texture2D(tex, texcoord + direction * distortion.g).g;\n\
color.b = texture2D(tex, texcoord + direction * distortion.b).b;\n\
}\n\
return vec4(clamp(color, 0.0, 1.0), 0.0);\n\
}\n\
void main(void)\n\
{\n\
vec4 originalColor = texture2D(colorTexture, v_textureCoordinates);\n\
vec3 rgb = originalColor.rgb;\n\
bool isSpace = length(czm_viewerPositionWC.xyz) > DISTANCE_TO_SPACE;\n\
vec4 sunPos = czm_morphTime == 1.0 ? vec4(czm_sunPositionWC, 1.0) : vec4(czm_sunPositionColumbusView.zxy, 1.0);\n\
vec4 sunPositionEC = czm_view * sunPos;\n\
vec4 sunPositionWC = czm_eyeToWindowCoordinates(sunPositionEC);\n\
sunPos = czm_viewportOrthographic * vec4(sunPositionWC.xy, -sunPositionWC.z, 1.0);\n\
if(!isSpace || !((sunPos.x >= -1.1 && sunPos.x <= 1.1) && (sunPos.y >= -1.1 && sunPos.y <= 1.1)))\n\
{\n\
gl_FragColor = originalColor;\n\
return;\n\
}\n\
vec2 texcoord = vec2(1.0) - v_textureCoordinates;\n\
vec2 pixelSize = czm_pixelRatio / czm_viewport.zw;\n\
vec2 invPixelSize = 1.0 / pixelSize;\n\
vec3 distortionVec = pixelSize.x * vec3(-distortion, 0.0, distortion);\n\
vec2 ghostVec = (vec2(0.5) - texcoord) * ghostDispersal;\n\
vec3 direction = normalize(vec3(ghostVec, 0.0));\n\
vec4 result = vec4(0.0);\n\
vec4 ghost = vec4(0.0);\n\
for (int i = 0; i < 4; ++i)\n\
{\n\
vec2 offset = fract(texcoord + ghostVec * float(i));\n\
ghost += textureDistorted(colorTexture, offset, direction.xy, distortionVec, isSpace);\n\
}\n\
result += ghost;\n\
vec2 haloVec = normalize(ghostVec) * haloWidth;\n\
float weightForHalo = length(vec2(0.5) - fract(texcoord + haloVec)) / length(vec2(0.5));\n\
weightForHalo = pow(1.0 - weightForHalo, 5.0);\n\
result += textureDistorted(colorTexture, texcoord + haloVec, direction.xy, distortionVec, isSpace) * weightForHalo * 1.5;\n\
vec2 dirtTexCoords = (v_textureCoordinates * invPixelSize) / dirtTextureDimensions;\n\
if (dirtTexCoords.x > 1.0)\n\
{\n\
dirtTexCoords.x = mod(floor(dirtTexCoords.x), 2.0) == 1.0 ? 1.0 - fract(dirtTexCoords.x) :  fract(dirtTexCoords.x);\n\
}\n\
if (dirtTexCoords.y > 1.0)\n\
{\n\
dirtTexCoords.y = mod(floor(dirtTexCoords.y), 2.0) == 1.0 ? 1.0 - fract(dirtTexCoords.y) :  fract(dirtTexCoords.y);\n\
}\n\
result += dirtAmount * texture2D(dirtTexture, dirtTexCoords);\n\
float camrot = czm_view[0].z + czm_view[1].y;\n\
float cosValue = cos(camrot);\n\
float sinValue = sin(camrot);\n\
mat3 rotation = mat3(\n\
cosValue, -sinValue, 0.0,\n\
sinValue, cosValue, 0.0,\n\
0.0, 0.0, 1.0\n\
);\n\
vec3 st1 = vec3(v_textureCoordinates * 2.0 - vec2(1.0), 1.0);\n\
vec3 st2 = vec3((rotation * st1).xy, 1.0);\n\
vec3 st3 = st2 * 0.5 + vec3(0.5);\n\
vec2 lensStarTexcoord = st3.xy;\n\
float weightForLensFlare = length(vec3(sunPos.xy, 0.0));\n\
float oneMinusWeightForLensFlare = max(1.0 - weightForLensFlare, 0.0);\n\
if (!isSpace)\n\
{\n\
result *= oneMinusWeightForLensFlare * intensity * 0.2;\n\
}\n\
else\n\
{\n\
result *= oneMinusWeightForLensFlare * intensity;\n\
result *= texture2D(starTexture, lensStarTexcoord) * pow(weightForLensFlare, 1.0) * max((1.0 - length(vec3(st1.xy, 0.0))), 0.0) * 2.0;\n\
}\n\
result += texture2D(colorTexture, v_textureCoordinates);\n\
gl_FragColor = result;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ModifiedReinhardTonemapping = "uniform sampler2D colorTexture;\n\
uniform vec3 white;\n\
varying vec2 v_textureCoordinates;\n\
#ifdef AUTO_EXPOSURE\n\
uniform sampler2D autoExposure;\n\
#endif\n\
void main()\n\
{\n\
vec4 fragmentColor = texture2D(colorTexture, v_textureCoordinates);\n\
vec3 color = fragmentColor.rgb;\n\
#ifdef AUTO_EXPOSURE\n\
float exposure = texture2D(autoExposure, vec2(0.5)).r;\n\
color /= exposure;\n\
#endif\n\
color = (color * (1.0 + color / white)) / (1.0 + color);\n\
color = czm_inverseGamma(color);\n\
gl_FragColor = vec4(color, fragmentColor.a);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var NightVision = "uniform sampler2D colorTexture;\n\
varying vec2 v_textureCoordinates;\n\
float rand(vec2 co)\n\
{\n\
return fract(sin(dot(co.xy ,vec2(12.9898, 78.233))) * 43758.5453);\n\
}\n\
void main(void)\n\
{\n\
float noiseValue = rand(v_textureCoordinates + sin(czm_frameNumber)) * 0.1;\n\
vec3 rgb = texture2D(colorTexture, v_textureCoordinates).rgb;\n\
vec3 green = vec3(0.0, 1.0, 0.0);\n\
gl_FragColor = vec4((noiseValue + rgb) * green, 1.0);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var ReinhardTonemapping = "uniform sampler2D colorTexture;\n\
varying vec2 v_textureCoordinates;\n\
#ifdef AUTO_EXPOSURE\n\
uniform sampler2D autoExposure;\n\
#endif\n\
void main()\n\
{\n\
vec4 fragmentColor = texture2D(colorTexture, v_textureCoordinates);\n\
vec3 color = fragmentColor.rgb;\n\
#ifdef AUTO_EXPOSURE\n\
float exposure = texture2D(autoExposure, vec2(0.5)).r;\n\
color /= exposure;\n\
#endif\n\
color = color / (1.0 + color);\n\
color = czm_inverseGamma(color);\n\
gl_FragColor = vec4(color, fragmentColor.a);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var Silhouette = "uniform sampler2D colorTexture;\n\
uniform sampler2D silhouetteTexture;\n\
varying vec2 v_textureCoordinates;\n\
void main(void)\n\
{\n\
vec4 silhouetteColor = texture2D(silhouetteTexture, v_textureCoordinates);\n\
vec4 color = texture2D(colorTexture, v_textureCoordinates);\n\
gl_FragColor = mix(color, silhouetteColor, silhouetteColor.a);\n\
}\n\
";

  /**
   * @license
   * Copyright (c) 2014-2015, NVIDIA CORPORATION. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *  * Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *  * Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *  * Neither the name of NVIDIA CORPORATION nor the names of its
   *    contributors may be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  //This file is automatically rebuilt by the Cesium build process.
  var FXAA3_11 = "#if (FXAA_QUALITY_PRESET == 10)\n\
#define FXAA_QUALITY_PS 3\n\
#define FXAA_QUALITY_P0 1.5\n\
#define FXAA_QUALITY_P1 3.0\n\
#define FXAA_QUALITY_P2 12.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 11)\n\
#define FXAA_QUALITY_PS 4\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 3.0\n\
#define FXAA_QUALITY_P3 12.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 12)\n\
#define FXAA_QUALITY_PS 5\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 4.0\n\
#define FXAA_QUALITY_P4 12.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 13)\n\
#define FXAA_QUALITY_PS 6\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 4.0\n\
#define FXAA_QUALITY_P5 12.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 14)\n\
#define FXAA_QUALITY_PS 7\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 4.0\n\
#define FXAA_QUALITY_P6 12.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 15)\n\
#define FXAA_QUALITY_PS 8\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 2.0\n\
#define FXAA_QUALITY_P6 4.0\n\
#define FXAA_QUALITY_P7 12.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 20)\n\
#define FXAA_QUALITY_PS 3\n\
#define FXAA_QUALITY_P0 1.5\n\
#define FXAA_QUALITY_P1 2.0\n\
#define FXAA_QUALITY_P2 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 21)\n\
#define FXAA_QUALITY_PS 4\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 22)\n\
#define FXAA_QUALITY_PS 5\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 23)\n\
#define FXAA_QUALITY_PS 6\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 24)\n\
#define FXAA_QUALITY_PS 7\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 3.0\n\
#define FXAA_QUALITY_P6 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 25)\n\
#define FXAA_QUALITY_PS 8\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 2.0\n\
#define FXAA_QUALITY_P6 4.0\n\
#define FXAA_QUALITY_P7 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 26)\n\
#define FXAA_QUALITY_PS 9\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 2.0\n\
#define FXAA_QUALITY_P6 2.0\n\
#define FXAA_QUALITY_P7 4.0\n\
#define FXAA_QUALITY_P8 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 27)\n\
#define FXAA_QUALITY_PS 10\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 2.0\n\
#define FXAA_QUALITY_P6 2.0\n\
#define FXAA_QUALITY_P7 2.0\n\
#define FXAA_QUALITY_P8 4.0\n\
#define FXAA_QUALITY_P9 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 28)\n\
#define FXAA_QUALITY_PS 11\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 2.0\n\
#define FXAA_QUALITY_P6 2.0\n\
#define FXAA_QUALITY_P7 2.0\n\
#define FXAA_QUALITY_P8 2.0\n\
#define FXAA_QUALITY_P9 4.0\n\
#define FXAA_QUALITY_P10 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 29)\n\
#define FXAA_QUALITY_PS 12\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.5\n\
#define FXAA_QUALITY_P2 2.0\n\
#define FXAA_QUALITY_P3 2.0\n\
#define FXAA_QUALITY_P4 2.0\n\
#define FXAA_QUALITY_P5 2.0\n\
#define FXAA_QUALITY_P6 2.0\n\
#define FXAA_QUALITY_P7 2.0\n\
#define FXAA_QUALITY_P8 2.0\n\
#define FXAA_QUALITY_P9 2.0\n\
#define FXAA_QUALITY_P10 4.0\n\
#define FXAA_QUALITY_P11 8.0\n\
#endif\n\
#if (FXAA_QUALITY_PRESET == 39)\n\
#define FXAA_QUALITY_PS 12\n\
#define FXAA_QUALITY_P0 1.0\n\
#define FXAA_QUALITY_P1 1.0\n\
#define FXAA_QUALITY_P2 1.0\n\
#define FXAA_QUALITY_P3 1.0\n\
#define FXAA_QUALITY_P4 1.0\n\
#define FXAA_QUALITY_P5 1.5\n\
#define FXAA_QUALITY_P6 2.0\n\
#define FXAA_QUALITY_P7 2.0\n\
#define FXAA_QUALITY_P8 2.0\n\
#define FXAA_QUALITY_P9 2.0\n\
#define FXAA_QUALITY_P10 4.0\n\
#define FXAA_QUALITY_P11 8.0\n\
#endif\n\
#define FxaaBool bool\n\
#define FxaaFloat float\n\
#define FxaaFloat2 vec2\n\
#define FxaaFloat3 vec3\n\
#define FxaaFloat4 vec4\n\
#define FxaaHalf float\n\
#define FxaaHalf2 vec2\n\
#define FxaaHalf3 vec3\n\
#define FxaaHalf4 vec4\n\
#define FxaaInt2 vec2\n\
#define FxaaTex sampler2D\n\
#define FxaaSat(x) clamp(x, 0.0, 1.0)\n\
#define FxaaTexTop(t, p) texture2D(t, p)\n\
#define FxaaTexOff(t, p, o, r) texture2D(t, p + (o * r))\n\
FxaaFloat FxaaLuma(FxaaFloat4 rgba) { return rgba.y; }\n\
FxaaFloat4 FxaaPixelShader(\n\
FxaaFloat2 pos,\n\
FxaaTex tex,\n\
FxaaFloat2 fxaaQualityRcpFrame,\n\
FxaaFloat fxaaQualitySubpix,\n\
FxaaFloat fxaaQualityEdgeThreshold,\n\
FxaaFloat fxaaQualityEdgeThresholdMin\n\
) {\n\
FxaaFloat2 posM;\n\
posM.x = pos.x;\n\
posM.y = pos.y;\n\
FxaaFloat4 rgbyM = FxaaTexTop(tex, posM);\n\
#define lumaM rgbyM.y\n\
FxaaFloat lumaS = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2( 0, 1), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaE = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2( 1, 0), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaN = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2( 0,-1), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaW = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2(-1, 0), fxaaQualityRcpFrame.xy));\n\
FxaaFloat maxSM = max(lumaS, lumaM);\n\
FxaaFloat minSM = min(lumaS, lumaM);\n\
FxaaFloat maxESM = max(lumaE, maxSM);\n\
FxaaFloat minESM = min(lumaE, minSM);\n\
FxaaFloat maxWN = max(lumaN, lumaW);\n\
FxaaFloat minWN = min(lumaN, lumaW);\n\
FxaaFloat rangeMax = max(maxWN, maxESM);\n\
FxaaFloat rangeMin = min(minWN, minESM);\n\
FxaaFloat rangeMaxScaled = rangeMax * fxaaQualityEdgeThreshold;\n\
FxaaFloat range = rangeMax - rangeMin;\n\
FxaaFloat rangeMaxClamped = max(fxaaQualityEdgeThresholdMin, rangeMaxScaled);\n\
FxaaBool earlyExit = range < rangeMaxClamped;\n\
if(earlyExit)\n\
return rgbyM;\n\
FxaaFloat lumaNW = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2(-1,-1), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaSE = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2( 1, 1), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaNE = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2( 1,-1), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaSW = FxaaLuma(FxaaTexOff(tex, posM, FxaaInt2(-1, 1), fxaaQualityRcpFrame.xy));\n\
FxaaFloat lumaNS = lumaN + lumaS;\n\
FxaaFloat lumaWE = lumaW + lumaE;\n\
FxaaFloat subpixRcpRange = 1.0/range;\n\
FxaaFloat subpixNSWE = lumaNS + lumaWE;\n\
FxaaFloat edgeHorz1 = (-2.0 * lumaM) + lumaNS;\n\
FxaaFloat edgeVert1 = (-2.0 * lumaM) + lumaWE;\n\
FxaaFloat lumaNESE = lumaNE + lumaSE;\n\
FxaaFloat lumaNWNE = lumaNW + lumaNE;\n\
FxaaFloat edgeHorz2 = (-2.0 * lumaE) + lumaNESE;\n\
FxaaFloat edgeVert2 = (-2.0 * lumaN) + lumaNWNE;\n\
FxaaFloat lumaNWSW = lumaNW + lumaSW;\n\
FxaaFloat lumaSWSE = lumaSW + lumaSE;\n\
FxaaFloat edgeHorz4 = (abs(edgeHorz1) * 2.0) + abs(edgeHorz2);\n\
FxaaFloat edgeVert4 = (abs(edgeVert1) * 2.0) + abs(edgeVert2);\n\
FxaaFloat edgeHorz3 = (-2.0 * lumaW) + lumaNWSW;\n\
FxaaFloat edgeVert3 = (-2.0 * lumaS) + lumaSWSE;\n\
FxaaFloat edgeHorz = abs(edgeHorz3) + edgeHorz4;\n\
FxaaFloat edgeVert = abs(edgeVert3) + edgeVert4;\n\
FxaaFloat subpixNWSWNESE = lumaNWSW + lumaNESE;\n\
FxaaFloat lengthSign = fxaaQualityRcpFrame.x;\n\
FxaaBool horzSpan = edgeHorz >= edgeVert;\n\
FxaaFloat subpixA = subpixNSWE * 2.0 + subpixNWSWNESE;\n\
if(!horzSpan) lumaN = lumaW;\n\
if(!horzSpan) lumaS = lumaE;\n\
if(horzSpan) lengthSign = fxaaQualityRcpFrame.y;\n\
FxaaFloat subpixB = (subpixA * (1.0/12.0)) - lumaM;\n\
FxaaFloat gradientN = lumaN - lumaM;\n\
FxaaFloat gradientS = lumaS - lumaM;\n\
FxaaFloat lumaNN = lumaN + lumaM;\n\
FxaaFloat lumaSS = lumaS + lumaM;\n\
FxaaBool pairN = abs(gradientN) >= abs(gradientS);\n\
FxaaFloat gradient = max(abs(gradientN), abs(gradientS));\n\
if(pairN) lengthSign = -lengthSign;\n\
FxaaFloat subpixC = FxaaSat(abs(subpixB) * subpixRcpRange);\n\
FxaaFloat2 posB;\n\
posB.x = posM.x;\n\
posB.y = posM.y;\n\
FxaaFloat2 offNP;\n\
offNP.x = (!horzSpan) ? 0.0 : fxaaQualityRcpFrame.x;\n\
offNP.y = ( horzSpan) ? 0.0 : fxaaQualityRcpFrame.y;\n\
if(!horzSpan) posB.x += lengthSign * 0.5;\n\
if( horzSpan) posB.y += lengthSign * 0.5;\n\
FxaaFloat2 posN;\n\
posN.x = posB.x - offNP.x * FXAA_QUALITY_P0;\n\
posN.y = posB.y - offNP.y * FXAA_QUALITY_P0;\n\
FxaaFloat2 posP;\n\
posP.x = posB.x + offNP.x * FXAA_QUALITY_P0;\n\
posP.y = posB.y + offNP.y * FXAA_QUALITY_P0;\n\
FxaaFloat subpixD = ((-2.0)*subpixC) + 3.0;\n\
FxaaFloat lumaEndN = FxaaLuma(FxaaTexTop(tex, posN));\n\
FxaaFloat subpixE = subpixC * subpixC;\n\
FxaaFloat lumaEndP = FxaaLuma(FxaaTexTop(tex, posP));\n\
if(!pairN) lumaNN = lumaSS;\n\
FxaaFloat gradientScaled = gradient * 1.0/4.0;\n\
FxaaFloat lumaMM = lumaM - lumaNN * 0.5;\n\
FxaaFloat subpixF = subpixD * subpixE;\n\
FxaaBool lumaMLTZero = lumaMM < 0.0;\n\
lumaEndN -= lumaNN * 0.5;\n\
lumaEndP -= lumaNN * 0.5;\n\
FxaaBool doneN = abs(lumaEndN) >= gradientScaled;\n\
FxaaBool doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P1;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P1;\n\
FxaaBool doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P1;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P1;\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P2;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P2;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P2;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P2;\n\
#if (FXAA_QUALITY_PS > 3)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P3;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P3;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P3;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P3;\n\
#if (FXAA_QUALITY_PS > 4)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P4;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P4;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P4;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P4;\n\
#if (FXAA_QUALITY_PS > 5)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P5;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P5;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P5;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P5;\n\
#if (FXAA_QUALITY_PS > 6)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P6;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P6;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P6;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P6;\n\
#if (FXAA_QUALITY_PS > 7)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P7;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P7;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P7;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P7;\n\
#if (FXAA_QUALITY_PS > 8)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P8;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P8;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P8;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P8;\n\
#if (FXAA_QUALITY_PS > 9)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P9;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P9;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P9;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P9;\n\
#if (FXAA_QUALITY_PS > 10)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P10;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P10;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P10;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P10;\n\
#if (FXAA_QUALITY_PS > 11)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P11;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P11;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P11;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P11;\n\
#if (FXAA_QUALITY_PS > 12)\n\
if(doneNP) {\n\
if(!doneN) lumaEndN = FxaaLuma(FxaaTexTop(tex, posN.xy));\n\
if(!doneP) lumaEndP = FxaaLuma(FxaaTexTop(tex, posP.xy));\n\
if(!doneN) lumaEndN = lumaEndN - lumaNN * 0.5;\n\
if(!doneP) lumaEndP = lumaEndP - lumaNN * 0.5;\n\
doneN = abs(lumaEndN) >= gradientScaled;\n\
doneP = abs(lumaEndP) >= gradientScaled;\n\
if(!doneN) posN.x -= offNP.x * FXAA_QUALITY_P12;\n\
if(!doneN) posN.y -= offNP.y * FXAA_QUALITY_P12;\n\
doneNP = (!doneN) || (!doneP);\n\
if(!doneP) posP.x += offNP.x * FXAA_QUALITY_P12;\n\
if(!doneP) posP.y += offNP.y * FXAA_QUALITY_P12;\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
#endif\n\
}\n\
FxaaFloat dstN = posM.x - posN.x;\n\
FxaaFloat dstP = posP.x - posM.x;\n\
if(!horzSpan) dstN = posM.y - posN.y;\n\
if(!horzSpan) dstP = posP.y - posM.y;\n\
FxaaBool goodSpanN = (lumaEndN < 0.0) != lumaMLTZero;\n\
FxaaFloat spanLength = (dstP + dstN);\n\
FxaaBool goodSpanP = (lumaEndP < 0.0) != lumaMLTZero;\n\
FxaaFloat spanLengthRcp = 1.0/spanLength;\n\
FxaaBool directionN = dstN < dstP;\n\
FxaaFloat dst = min(dstN, dstP);\n\
FxaaBool goodSpan = directionN ? goodSpanN : goodSpanP;\n\
FxaaFloat subpixG = subpixF * subpixF;\n\
FxaaFloat pixelOffset = (dst * (-spanLengthRcp)) + 0.5;\n\
FxaaFloat subpixH = subpixG * fxaaQualitySubpix;\n\
FxaaFloat pixelOffsetGood = goodSpan ? pixelOffset : 0.0;\n\
FxaaFloat pixelOffsetSubpix = max(pixelOffsetGood, subpixH);\n\
if(!horzSpan) posM.x += pixelOffsetSubpix * lengthSign;\n\
if( horzSpan) posM.y += pixelOffsetSubpix * lengthSign;\n\
return FxaaFloat4(FxaaTexTop(tex, posM).xyz, lumaM);\n\
}\n\
";

  /**
   * A collection of {@link PostProcessStage}s or other post-process composite stages that execute together logically.
   * <p>
   * All stages are executed in the order of the array. The input texture changes based on the value of <code>inputPreviousStageTexture</code>.
   * If <code>inputPreviousStageTexture</code> is <code>true</code>, the input to each stage is the output texture rendered to by the scene or of the stage that executed before it.
   * If <code>inputPreviousStageTexture</code> is <code>false</code>, the input texture is the same for each stage in the composite. The input texture is the texture rendered to by the scene
   * or the output texture of the previous stage.
   * </p>
   *
   * @alias PostProcessStageComposite
   * @constructor
   *
   * @param {Object} options An object with the following properties:
   * @param {Array} options.stages An array of {@link PostProcessStage}s or composites to be executed in order.
   * @param {Boolean} [options.inputPreviousStageTexture=true] Whether to execute each post-process stage where the input to one stage is the output of the previous. Otherwise, the input to each contained stage is the output of the stage that executed before the composite.
   * @param {String} [options.name=createGuid()] The unique name of this post-process stage for reference by other composites. If a name is not supplied, a GUID will be generated.
   * @param {Object} [options.uniforms] An alias to the uniforms of post-process stages.
   *
   * @exception {DeveloperError} options.stages.length must be greater than 0.0.
   *
   * @see PostProcessStage
   *
   * @example
   * // Example 1: separable blur filter
   * // The input to blurXDirection is the texture rendered to by the scene or the output of the previous stage.
   * // The input to blurYDirection is the texture rendered to by blurXDirection.
   * scene.postProcessStages.add(new Cesium.PostProcessStageComposite({
   *     stages : [blurXDirection, blurYDirection]
   * }));
   *
   * @example
   * // Example 2: referencing the output of another post-process stage
   * scene.postProcessStages.add(new Cesium.PostProcessStageComposite({
   *     inputPreviousStageTexture : false,
   *     stages : [
   *         // The same as Example 1.
   *         new Cesium.PostProcessStageComposite({
   *             inputPreviousStageTexture : true
   *             stages : [blurXDirection, blurYDirection],
   *             name : 'blur'
   *         }),
   *         // The input texture for this stage is the same input texture to blurXDirection since inputPreviousStageTexture is false
   *         new Cesium.PostProcessStage({
   *             fragmentShader : compositeShader,
   *             uniforms : {
   *                 blurTexture : 'blur' // The output of the composite with name 'blur' (the texture that blurYDirection rendered to).
   *             }
   *         })
   *     ]
   * });
   *
   * @example
   * // Example 3: create a uniform alias
   * var uniforms = {};
   * Cesium.defineProperties(uniforms, {
   *     filterSize : {
   *         get : function() {
   *             return blurXDirection.uniforms.filterSize;
   *         },
   *         set : function(value) {
   *             blurXDirection.uniforms.filterSize = blurYDirection.uniforms.filterSize = value;
   *         }
   *     }
   * });
   * scene.postProcessStages.add(new Cesium.PostProcessStageComposite({
   *     stages : [blurXDirection, blurYDirection],
   *     uniforms : uniforms
   * }));
   */
  function PostProcessStageComposite(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.defined("options.stages", options.stages);
    Check.typeOf.number.greaterThan(
      "options.stages.length",
      options.stages.length,
      0
    );
    //>>includeEnd('debug');

    this._stages = options.stages;
    this._inputPreviousStageTexture = defaultValue(
      options.inputPreviousStageTexture,
      true
    );

    var name = options.name;
    if (!defined(name)) {
      name = createGuid();
    }
    this._name = name;

    this._uniforms = options.uniforms;

    // used by PostProcessStageCollection
    this._textureCache = undefined;
    this._index = undefined;

    this._selected = undefined;
    this._selectedShadow = undefined;
    this._parentSelected = undefined;
    this._parentSelectedShadow = undefined;
    this._combinedSelected = undefined;
    this._combinedSelectedShadow = undefined;
    this._selectedLength = 0;
    this._parentSelectedLength = 0;
    this._selectedDirty = true;
  }

  Object.defineProperties(PostProcessStageComposite.prototype, {
    /**
     * Determines if this post-process stage is ready to be executed.
     *
     * @memberof PostProcessStageComposite.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        var stages = this._stages;
        var length = stages.length;
        for (var i = 0; i < length; ++i) {
          if (!stages[i].ready) {
            return false;
          }
        }
        return true;
      },
    },
    /**
     * The unique name of this post-process stage for reference by other stages in a PostProcessStageComposite.
     *
     * @memberof PostProcessStageComposite.prototype
     * @type {String}
     * @readonly
     */
    name: {
      get: function () {
        return this._name;
      },
    },
    /**
     * Whether or not to execute this post-process stage when ready.
     *
     * @memberof PostProcessStageComposite.prototype
     * @type {Boolean}
     */
    enabled: {
      get: function () {
        return this._stages[0].enabled;
      },
      set: function (value) {
        var stages = this._stages;
        var length = stages.length;
        for (var i = 0; i < length; ++i) {
          stages[i].enabled = value;
        }
      },
    },
    /**
     * An alias to the uniform values of the post-process stages. May be <code>undefined</code>; in which case, get each stage to set uniform values.
     * @memberof PostProcessStageComposite.prototype
     * @type {Object}
     */
    uniforms: {
      get: function () {
        return this._uniforms;
      },
    },
    /**
     * All post-process stages are executed in the order of the array. The input texture changes based on the value of <code>inputPreviousStageTexture</code>.
     * If <code>inputPreviousStageTexture</code> is <code>true</code>, the input to each stage is the output texture rendered to by the scene or of the stage that executed before it.
     * If <code>inputPreviousStageTexture</code> is <code>false</code>, the input texture is the same for each stage in the composite. The input texture is the texture rendered to by the scene
     * or the output texture of the previous stage.
     *
     * @memberof PostProcessStageComposite.prototype
     * @type {Boolean}
     * @readonly
     */
    inputPreviousStageTexture: {
      get: function () {
        return this._inputPreviousStageTexture;
      },
    },
    /**
     * The number of post-process stages in this composite.
     *
     * @memberof PostProcessStageComposite.prototype
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._stages.length;
      },
    },
    /**
     * The features selected for applying the post-process.
     *
     * @memberof PostProcessStageComposite.prototype
     * @type {Array}
     */
    selected: {
      get: function () {
        return this._selected;
      },
      set: function (value) {
        this._selected = value;
      },
    },
    /**
     * @private
     */
    parentSelected: {
      get: function () {
        return this._parentSelected;
      },
      set: function (value) {
        this._parentSelected = value;
      },
    },
  });

  /**
   * @private
   */
  PostProcessStageComposite.prototype._isSupported = function (context) {
    var stages = this._stages;
    var length = stages.length;
    for (var i = 0; i < length; ++i) {
      if (!stages[i]._isSupported(context)) {
        return false;
      }
    }
    return true;
  };

  /**
   * Gets the post-process stage at <code>index</code>
   *
   * @param {Number} index The index of the post-process stage or composite.
   * @return {PostProcessStage|PostProcessStageComposite} The post-process stage or composite at index.
   *
   * @exception {DeveloperError} index must be greater than or equal to 0.
   * @exception {DeveloperError} index must be less than {@link PostProcessStageComposite#length}.
   */
  PostProcessStageComposite.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThan("index", index, this.length);
    //>>includeEnd('debug');
    return this._stages[index];
  };

  function isSelectedTextureDirty$1(stage) {
    var length = defined(stage._selected) ? stage._selected.length : 0;
    var parentLength = defined(stage._parentSelected) ? stage._parentSelected : 0;
    var dirty =
      stage._selected !== stage._selectedShadow ||
      length !== stage._selectedLength;
    dirty =
      dirty ||
      stage._parentSelected !== stage._parentSelectedShadow ||
      parentLength !== stage._parentSelectedLength;

    if (defined(stage._selected) && defined(stage._parentSelected)) {
      stage._combinedSelected = stage._selected.concat(stage._parentSelected);
    } else if (defined(stage._parentSelected)) {
      stage._combinedSelected = stage._parentSelected;
    } else {
      stage._combinedSelected = stage._selected;
    }

    if (!dirty && defined(stage._combinedSelected)) {
      if (!defined(stage._combinedSelectedShadow)) {
        return true;
      }

      length = stage._combinedSelected.length;
      for (var i = 0; i < length; ++i) {
        if (stage._combinedSelected[i] !== stage._combinedSelectedShadow[i]) {
          return true;
        }
      }
    }
    return dirty;
  }

  /**
   * A function that will be called before execute. Updates each post-process stage in the composite.
   * @param {Context} context The context.
   * @param {Boolean} useLogDepth Whether the scene uses a logarithmic depth buffer.
   * @private
   */
  PostProcessStageComposite.prototype.update = function (context, useLogDepth) {
    this._selectedDirty = isSelectedTextureDirty$1(this);

    this._selectedShadow = this._selected;
    this._parentSelectedShadow = this._parentSelected;
    this._combinedSelectedShadow = this._combinedSelected;
    this._selectedLength = defined(this._selected) ? this._selected.length : 0;
    this._parentSelectedLength = defined(this._parentSelected)
      ? this._parentSelected.length
      : 0;

    var stages = this._stages;
    var length = stages.length;
    for (var i = 0; i < length; ++i) {
      var stage = stages[i];
      if (this._selectedDirty) {
        stage.parentSelected = this._combinedSelected;
      }
      stage.update(context, useLogDepth);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PostProcessStageComposite#destroy
   */
  PostProcessStageComposite.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PostProcessStageComposite#isDestroyed
   */
  PostProcessStageComposite.prototype.destroy = function () {
    var stages = this._stages;
    var length = stages.length;
    for (var i = 0; i < length; ++i) {
      stages[i].destroy();
    }
    return destroyObject(this);
  };

  /**
   * Contains functions for creating common post-process stages.
   *
   * @namespace PostProcessStageLibrary
   */
  var PostProcessStageLibrary = {};

  function createBlur(name) {
    var delta = 1.0;
    var sigma = 2.0;
    var stepSize = 1.0;

    var blurShader = "#define USE_STEP_SIZE\n" + GaussianBlur1D;
    var blurX = new PostProcessStage({
      name: name + "_x_direction",
      fragmentShader: blurShader,
      uniforms: {
        delta: delta,
        sigma: sigma,
        stepSize: stepSize,
        direction: 0.0,
      },
      sampleMode: PostProcessStageSampleMode.LINEAR,
    });
    var blurY = new PostProcessStage({
      name: name + "_y_direction",
      fragmentShader: blurShader,
      uniforms: {
        delta: delta,
        sigma: sigma,
        stepSize: stepSize,
        direction: 1.0,
      },
      sampleMode: PostProcessStageSampleMode.LINEAR,
    });

    var uniforms = {};
    Object.defineProperties(uniforms, {
      delta: {
        get: function () {
          return blurX.uniforms.delta;
        },
        set: function (value) {
          var blurXUniforms = blurX.uniforms;
          var blurYUniforms = blurY.uniforms;
          blurXUniforms.delta = blurYUniforms.delta = value;
        },
      },
      sigma: {
        get: function () {
          return blurX.uniforms.sigma;
        },
        set: function (value) {
          var blurXUniforms = blurX.uniforms;
          var blurYUniforms = blurY.uniforms;
          blurXUniforms.sigma = blurYUniforms.sigma = value;
        },
      },
      stepSize: {
        get: function () {
          return blurX.uniforms.stepSize;
        },
        set: function (value) {
          var blurXUniforms = blurX.uniforms;
          var blurYUniforms = blurY.uniforms;
          blurXUniforms.stepSize = blurYUniforms.stepSize = value;
        },
      },
    });
    return new PostProcessStageComposite({
      name: name,
      stages: [blurX, blurY],
      uniforms: uniforms,
    });
  }

  /**
   * Creates a post-process stage that applies a Gaussian blur to the input texture. This stage is usually applied in conjunction with another stage.
   * <p>
   * This stage has the following uniforms: <code>delta</code>, <code>sigma</code>, and <code>stepSize</code>.
   * </p>
   * <p>
   * <code>delta</code> and <code>sigma</code> are used to compute the weights of a Gaussian filter. The equation is <code>exp((-0.5 * delta * delta) / (sigma * sigma))</code>.
   * The default value for <code>delta</code> is <code>1.0</code>. The default value for <code>sigma</code> is <code>2.0</code>.
   * <code>stepSize</code> is the distance to the next texel. The default is <code>1.0</code>.
   * </p>
   * @return {PostProcessStageComposite} A post-process stage that applies a Gaussian blur to the input texture.
   */
  PostProcessStageLibrary.createBlurStage = function () {
    return createBlur("czm_blur");
  };

  /**
   * Creates a post-process stage that applies a depth of field effect.
   * <p>
   * Depth of field simulates camera focus. Objects in the scene that are in focus
   * will be clear whereas objects not in focus will be blurred.
   * </p>
   * <p>
   * This stage has the following uniforms: <code>focalDistance</code>, <code>delta</code>, <code>sigma</code>, and <code>stepSize</code>.
   * </p>
   * <p>
   * <code>focalDistance</code> is the distance in meters from the camera to set the camera focus.
   * </p>
   * <p>
   * <code>delta</code>, <code>sigma</code>, and <code>stepSize</code> are the same properties as {@link PostProcessStageLibrary#createBlurStage}.
   * The blur is applied to the areas out of focus.
   * </p>
   * @return {PostProcessStageComposite} A post-process stage that applies a depth of field effect.
   */
  PostProcessStageLibrary.createDepthOfFieldStage = function () {
    var blur = createBlur("czm_depth_of_field_blur");
    var dof = new PostProcessStage({
      name: "czm_depth_of_field_composite",
      fragmentShader: DepthOfField,
      uniforms: {
        focalDistance: 5.0,
        blurTexture: blur.name,
      },
    });

    var uniforms = {};
    Object.defineProperties(uniforms, {
      focalDistance: {
        get: function () {
          return dof.uniforms.focalDistance;
        },
        set: function (value) {
          dof.uniforms.focalDistance = value;
        },
      },
      delta: {
        get: function () {
          return blur.uniforms.delta;
        },
        set: function (value) {
          blur.uniforms.delta = value;
        },
      },
      sigma: {
        get: function () {
          return blur.uniforms.sigma;
        },
        set: function (value) {
          blur.uniforms.sigma = value;
        },
      },
      stepSize: {
        get: function () {
          return blur.uniforms.stepSize;
        },
        set: function (value) {
          blur.uniforms.stepSize = value;
        },
      },
    });
    return new PostProcessStageComposite({
      name: "czm_depth_of_field",
      stages: [blur, dof],
      inputPreviousStageTexture: false,
      uniforms: uniforms,
    });
  };

  /**
   * Whether or not a depth of field stage is supported.
   * <p>
   * This stage requires the WEBGL_depth_texture extension.
   * </p>
   *
   * @param {Scene} scene The scene.
   * @return {Boolean} Whether this post process stage is supported.
   *
   * @see {Context#depthTexture}
   * @see {@link http://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/|WEBGL_depth_texture}
   */
  PostProcessStageLibrary.isDepthOfFieldSupported = function (scene) {
    return scene.context.depthTexture;
  };

  /**
   * Creates a post-process stage that detects edges.
   * <p>
   * Writes the color to the output texture with alpha set to 1.0 when it is on an edge.
   * </p>
   * <p>
   * This stage has the following uniforms: <code>color</code> and <code>length</code>
   * </p>
   * <ul>
   * <li><code>color</code> is the color of the highlighted edge. The default is {@link Color#BLACK}.</li>
   * <li><code>length</code> is the length of the edges in pixels. The default is <code>0.5</code>.</li>
   * </ul>
   * <p>
   * This stage is not supported in 2D.
   * </p>
   * @return {PostProcessStageComposite} A post-process stage that applies an edge detection effect.
   *
   * @example
   * // multiple silhouette effects
   * var yellowEdge = Cesium.PostProcessLibrary.createEdgeDetectionStage();
   * yellowEdge.uniforms.color = Cesium.Color.YELLOW;
   * yellowEdge.selected = [feature0];
   *
   * var greenEdge = Cesium.PostProcessLibrary.createEdgeDetectionStage();
   * greenEdge.uniforms.color = Cesium.Color.LIME;
   * greenEdge.selected = [feature1];
   *
   * // draw edges around feature0 and feature1
   * postProcessStages.add(Cesium.PostProcessLibrary.createSilhouetteStage([yellowEdge, greenEdge]);
   */
  PostProcessStageLibrary.createEdgeDetectionStage = function () {
    // unique name generated on call so more than one effect can be added
    var name = createGuid();
    return new PostProcessStage({
      name: "czm_edge_detection_" + name,
      fragmentShader: EdgeDetection,
      uniforms: {
        length: 0.25,
        color: Color.clone(Color.BLACK),
      },
    });
  };

  /**
   * Whether or not an edge detection stage is supported.
   * <p>
   * This stage requires the WEBGL_depth_texture extension.
   * </p>
   *
   * @param {Scene} scene The scene.
   * @return {Boolean} Whether this post process stage is supported.
   *
   * @see {Context#depthTexture}
   * @see {@link http://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/|WEBGL_depth_texture}
   */
  PostProcessStageLibrary.isEdgeDetectionSupported = function (scene) {
    return scene.context.depthTexture;
  };

  function getSilhouetteEdgeDetection(edgeDetectionStages) {
    if (!defined(edgeDetectionStages)) {
      return PostProcessStageLibrary.createEdgeDetectionStage();
    }

    var edgeDetection = new PostProcessStageComposite({
      name: "czm_edge_detection_multiple",
      stages: edgeDetectionStages,
      inputPreviousStageTexture: false,
    });

    var compositeUniforms = {};
    var fsDecl = "";
    var fsLoop = "";
    for (var i = 0; i < edgeDetectionStages.length; ++i) {
      fsDecl += "uniform sampler2D edgeTexture" + i + "; \n";
      fsLoop +=
        "        vec4 edge" +
        i +
        " = texture2D(edgeTexture" +
        i +
        ", v_textureCoordinates); \n" +
        "        if (edge" +
        i +
        ".a > 0.0) \n" +
        "        { \n" +
        "            color = edge" +
        i +
        "; \n" +
        "            break; \n" +
        "        } \n";
      compositeUniforms["edgeTexture" + i] = edgeDetectionStages[i].name;
    }

    var fs =
      fsDecl +
      "varying vec2 v_textureCoordinates; \n" +
      "void main() { \n" +
      "    vec4 color = vec4(0.0); \n" +
      "    for (int i = 0; i < " +
      edgeDetectionStages.length +
      "; i++) \n" +
      "    { \n" +
      fsLoop +
      "    } \n" +
      "    gl_FragColor = color; \n" +
      "} \n";

    var edgeComposite = new PostProcessStage({
      name: "czm_edge_detection_combine",
      fragmentShader: fs,
      uniforms: compositeUniforms,
    });
    return new PostProcessStageComposite({
      name: "czm_edge_detection_composite",
      stages: [edgeDetection, edgeComposite],
    });
  }

  /**
   * Creates a post-process stage that applies a silhouette effect.
   * <p>
   * A silhouette effect composites the color from the edge detection pass with input color texture.
   * </p>
   * <p>
   * This stage has the following uniforms when <code>edgeDetectionStages</code> is <code>undefined</code>: <code>color</code> and <code>length</code>
   * </p>
   * <p>
   * <code>color</code> is the color of the highlighted edge. The default is {@link Color#BLACK}.
   * <code>length</code> is the length of the edges in pixels. The default is <code>0.5</code>.
   * </p>
   * @param {PostProcessStage[]} [edgeDetectionStages] An array of edge detection post process stages.
   * @return {PostProcessStageComposite} A post-process stage that applies a silhouette effect.
   */
  PostProcessStageLibrary.createSilhouetteStage = function (edgeDetectionStages) {
    var edgeDetection = getSilhouetteEdgeDetection(edgeDetectionStages);
    var silhouetteProcess = new PostProcessStage({
      name: "czm_silhouette_color_edges",
      fragmentShader: Silhouette,
      uniforms: {
        silhouetteTexture: edgeDetection.name,
      },
    });

    return new PostProcessStageComposite({
      name: "czm_silhouette",
      stages: [edgeDetection, silhouetteProcess],
      inputPreviousStageTexture: false,
      uniforms: edgeDetection.uniforms,
    });
  };

  /**
   * Whether or not a silhouette stage is supported.
   * <p>
   * This stage requires the WEBGL_depth_texture extension.
   * </p>
   *
   * @param {Scene} scene The scene.
   * @return {Boolean} Whether this post process stage is supported.
   *
   * @see {Context#depthTexture}
   * @see {@link http://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/|WEBGL_depth_texture}
   */
  PostProcessStageLibrary.isSilhouetteSupported = function (scene) {
    return scene.context.depthTexture;
  };

  /**
   * Creates a post-process stage that applies a bloom effect to the input texture.
   * <p>
   * A bloom effect adds glow effect, makes bright areas brighter, and dark areas darker.
   * </p>
   * <p>
   * This post-process stage has the following uniforms: <code>contrast</code>, <code>brightness</code>, <code>glowOnly</code>,
   * <code>delta</code>, <code>sigma</code>, and <code>stepSize</code>.
   * </p>
   * <ul>
   * <li><code>contrast</code> is a scalar value in the range [-255.0, 255.0] and affects the contract of the effect. The default value is <code>128.0</code>.</li>
   * <li><code>brightness</code> is a scalar value. The input texture RGB value is converted to hue, saturation, and brightness (HSB) then this value is
   * added to the brightness. The default value is <code>-0.3</code>.</li>
   * <li><code>glowOnly</code> is a boolean value. When <code>true</code>, only the glow effect will be shown. When <code>false</code>, the glow will be added to the input texture.
   * The default value is <code>false</code>. This is a debug option for viewing the effects when changing the other uniform values.</li>
   * </ul>
   * <p>
   * <code>delta</code>, <code>sigma</code>, and <code>stepSize</code> are the same properties as {@link PostProcessStageLibrary#createBlurStage}.
   * </p>
   * @return {PostProcessStageComposite} A post-process stage to applies a bloom effect.
   *
   * @private
   */
  PostProcessStageLibrary.createBloomStage = function () {
    var contrastBias = new PostProcessStage({
      name: "czm_bloom_contrast_bias",
      fragmentShader: ContrastBias,
      uniforms: {
        contrast: 128.0,
        brightness: -0.3,
      },
    });
    var blur = createBlur("czm_bloom_blur");
    var generateComposite = new PostProcessStageComposite({
      name: "czm_bloom_contrast_bias_blur",
      stages: [contrastBias, blur],
    });

    var bloomComposite = new PostProcessStage({
      name: "czm_bloom_generate_composite",
      fragmentShader: BloomComposite,
      uniforms: {
        glowOnly: false,
        bloomTexture: generateComposite.name,
      },
    });

    var uniforms = {};
    Object.defineProperties(uniforms, {
      glowOnly: {
        get: function () {
          return bloomComposite.uniforms.glowOnly;
        },
        set: function (value) {
          bloomComposite.uniforms.glowOnly = value;
        },
      },
      contrast: {
        get: function () {
          return contrastBias.uniforms.contrast;
        },
        set: function (value) {
          contrastBias.uniforms.contrast = value;
        },
      },
      brightness: {
        get: function () {
          return contrastBias.uniforms.brightness;
        },
        set: function (value) {
          contrastBias.uniforms.brightness = value;
        },
      },
      delta: {
        get: function () {
          return blur.uniforms.delta;
        },
        set: function (value) {
          blur.uniforms.delta = value;
        },
      },
      sigma: {
        get: function () {
          return blur.uniforms.sigma;
        },
        set: function (value) {
          blur.uniforms.sigma = value;
        },
      },
      stepSize: {
        get: function () {
          return blur.uniforms.stepSize;
        },
        set: function (value) {
          blur.uniforms.stepSize = value;
        },
      },
    });

    return new PostProcessStageComposite({
      name: "czm_bloom",
      stages: [generateComposite, bloomComposite],
      inputPreviousStageTexture: false,
      uniforms: uniforms,
    });
  };

  /**
   * Creates a post-process stage that Horizon-based Ambient Occlusion (HBAO) to the input texture.
   * <p>
   * Ambient occlusion simulates shadows from ambient light. These shadows would always be present when the
   * surface receives light and regardless of the light's position.
   * </p>
   * <p>
   * The uniforms have the following properties: <code>intensity</code>, <code>bias</code>, <code>lengthCap</code>,
   * <code>stepSize</code>, <code>frustumLength</code>, <code>randomTexture</code>, <code>ambientOcclusionOnly</code>,
   * <code>delta</code>, <code>sigma</code>, and <code>blurStepSize</code>.
   * </p>
   * <ul>
   * <li><code>intensity</code> is a scalar value used to lighten or darken the shadows exponentially. Higher values make the shadows darker. The default value is <code>3.0</code>.</li>
   * <li><code>bias</code> is a scalar value representing an angle in radians. If the dot product between the normal of the sample and the vector to the camera is less than this value,
   * sampling stops in the current direction. This is used to remove shadows from near planar edges. The default value is <code>0.1</code>.</li>
   * <li><code>lengthCap</code> is a scalar value representing a length in meters. If the distance from the current sample to first sample is greater than this value,
   * sampling stops in the current direction. The default value is <code>0.26</code>.</li>
   * <li><code>stepSize</code> is a scalar value indicating the distance to the next texel sample in the current direction. The default value is <code>1.95</code>.</li>
   * <li><code>frustumLength</code> is a scalar value in meters. If the current fragment has a distance from the camera greater than this value, ambient occlusion is not computed for the fragment.
   * The default value is <code>1000.0</code>.</li>
   * <li><code>randomTexture</code> is a texture where the red channel is a random value in [0.0, 1.0]. The default value is <code>undefined</code>. This texture needs to be set.</li>
   * <li><code>ambientOcclusionOnly</code> is a boolean value. When <code>true</code>, only the shadows generated are written to the output. When <code>false</code>, the input texture is modulated
   * with the ambient occlusion. This is a useful debug option for seeing the effects of changing the uniform values. The default value is <code>false</code>.</li>
   * </ul>
   * <p>
   * <code>delta</code>, <code>sigma</code>, and <code>blurStepSize</code> are the same properties as {@link PostProcessStageLibrary#createBlurStage}.
   * The blur is applied to the shadows generated from the image to make them smoother.
   * </p>
   * @return {PostProcessStageComposite} A post-process stage that applies an ambient occlusion effect.
   *
   * @private
   */
  PostProcessStageLibrary.createAmbientOcclusionStage = function () {
    var generate = new PostProcessStage({
      name: "czm_ambient_occlusion_generate",
      fragmentShader: AmbientOcclusionGenerate,
      uniforms: {
        intensity: 3.0,
        bias: 0.1,
        lengthCap: 0.26,
        stepSize: 1.95,
        frustumLength: 1000.0,
        randomTexture: undefined,
      },
    });
    var blur = createBlur("czm_ambient_occlusion_blur");
    blur.uniforms.stepSize = 0.86;
    var generateAndBlur = new PostProcessStageComposite({
      name: "czm_ambient_occlusion_generate_blur",
      stages: [generate, blur],
    });

    var ambientOcclusionModulate = new PostProcessStage({
      name: "czm_ambient_occlusion_composite",
      fragmentShader: AmbientOcclusionModulate,
      uniforms: {
        ambientOcclusionOnly: false,
        ambientOcclusionTexture: generateAndBlur.name,
      },
    });

    var uniforms = {};
    Object.defineProperties(uniforms, {
      intensity: {
        get: function () {
          return generate.uniforms.intensity;
        },
        set: function (value) {
          generate.uniforms.intensity = value;
        },
      },
      bias: {
        get: function () {
          return generate.uniforms.bias;
        },
        set: function (value) {
          generate.uniforms.bias = value;
        },
      },
      lengthCap: {
        get: function () {
          return generate.uniforms.lengthCap;
        },
        set: function (value) {
          generate.uniforms.lengthCap = value;
        },
      },
      stepSize: {
        get: function () {
          return generate.uniforms.stepSize;
        },
        set: function (value) {
          generate.uniforms.stepSize = value;
        },
      },
      frustumLength: {
        get: function () {
          return generate.uniforms.frustumLength;
        },
        set: function (value) {
          generate.uniforms.frustumLength = value;
        },
      },
      randomTexture: {
        get: function () {
          return generate.uniforms.randomTexture;
        },
        set: function (value) {
          generate.uniforms.randomTexture = value;
        },
      },
      delta: {
        get: function () {
          return blur.uniforms.delta;
        },
        set: function (value) {
          blur.uniforms.delta = value;
        },
      },
      sigma: {
        get: function () {
          return blur.uniforms.sigma;
        },
        set: function (value) {
          blur.uniforms.sigma = value;
        },
      },
      blurStepSize: {
        get: function () {
          return blur.uniforms.stepSize;
        },
        set: function (value) {
          blur.uniforms.stepSize = value;
        },
      },
      ambientOcclusionOnly: {
        get: function () {
          return ambientOcclusionModulate.uniforms.ambientOcclusionOnly;
        },
        set: function (value) {
          ambientOcclusionModulate.uniforms.ambientOcclusionOnly = value;
        },
      },
    });

    return new PostProcessStageComposite({
      name: "czm_ambient_occlusion",
      stages: [generateAndBlur, ambientOcclusionModulate],
      inputPreviousStageTexture: false,
      uniforms: uniforms,
    });
  };

  /**
   * Whether or not an ambient occlusion stage is supported.
   * <p>
   * This stage requires the WEBGL_depth_texture extension.
   * </p>
   *
   * @param {Scene} scene The scene.
   * @return {Boolean} Whether this post process stage is supported.
   *
   * @see {Context#depthTexture}
   * @see {@link http://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/|WEBGL_depth_texture}
   */
  PostProcessStageLibrary.isAmbientOcclusionSupported = function (scene) {
    return scene.context.depthTexture;
  };

  var fxaaFS = "#define FXAA_QUALITY_PRESET 39 \n" + FXAA3_11 + "\n" + FXAA;

  /**
   * Creates a post-process stage that applies Fast Approximate Anti-aliasing (FXAA) to the input texture.
   * @return {PostProcessStage} A post-process stage that applies Fast Approximate Anti-aliasing to the input texture.
   *
   * @private
   */
  PostProcessStageLibrary.createFXAAStage = function () {
    return new PostProcessStage({
      name: "czm_FXAA",
      fragmentShader: fxaaFS,
      sampleMode: PostProcessStageSampleMode.LINEAR,
    });
  };

  /**
   * Creates a post-process stage that applies ACES tonemapping operator.
   * @param {Boolean} useAutoExposure Whether or not to use auto-exposure.
   * @return {PostProcessStage} A post-process stage that applies ACES tonemapping operator.
   * @private
   */
  PostProcessStageLibrary.createAcesTonemappingStage = function (
    useAutoExposure
  ) {
    var fs = useAutoExposure ? "#define AUTO_EXPOSURE\n" : "";
    fs += AcesTonemapping;
    return new PostProcessStage({
      name: "czm_aces",
      fragmentShader: fs,
      uniforms: {
        autoExposure: undefined,
      },
    });
  };

  /**
   * Creates a post-process stage that applies filmic tonemapping operator.
   * @param {Boolean} useAutoExposure Whether or not to use auto-exposure.
   * @return {PostProcessStage} A post-process stage that applies filmic tonemapping operator.
   * @private
   */
  PostProcessStageLibrary.createFilmicTonemappingStage = function (
    useAutoExposure
  ) {
    var fs = useAutoExposure ? "#define AUTO_EXPOSURE\n" : "";
    fs += FilmicTonemapping;
    return new PostProcessStage({
      name: "czm_filmic",
      fragmentShader: fs,
      uniforms: {
        autoExposure: undefined,
      },
    });
  };

  /**
   * Creates a post-process stage that applies Reinhard tonemapping operator.
   * @param {Boolean} useAutoExposure Whether or not to use auto-exposure.
   * @return {PostProcessStage} A post-process stage that applies Reinhard tonemapping operator.
   * @private
   */
  PostProcessStageLibrary.createReinhardTonemappingStage = function (
    useAutoExposure
  ) {
    var fs = useAutoExposure ? "#define AUTO_EXPOSURE\n" : "";
    fs += ReinhardTonemapping;
    return new PostProcessStage({
      name: "czm_reinhard",
      fragmentShader: fs,
      uniforms: {
        autoExposure: undefined,
      },
    });
  };

  /**
   * Creates a post-process stage that applies modified Reinhard tonemapping operator.
   * @param {Boolean} useAutoExposure Whether or not to use auto-exposure.
   * @return {PostProcessStage} A post-process stage that applies modified Reinhard tonemapping operator.
   * @private
   */
  PostProcessStageLibrary.createModifiedReinhardTonemappingStage = function (
    useAutoExposure
  ) {
    var fs = useAutoExposure ? "#define AUTO_EXPOSURE\n" : "";
    fs += ModifiedReinhardTonemapping;
    return new PostProcessStage({
      name: "czm_modified_reinhard",
      fragmentShader: fs,
      uniforms: {
        white: Color.WHITE,
        autoExposure: undefined,
      },
    });
  };

  /**
   * Creates a post-process stage that finds the average luminance of the input texture.
   * @return {PostProcessStage} A post-process stage that finds the average luminance of the input texture.
   * @private
   */
  PostProcessStageLibrary.createAutoExposureStage = function () {
    return new AutoExposure();
  };

  /**
   * Creates a post-process stage that renders the input texture with black and white gradations.
   * <p>
   * This stage has one uniform value, <code>gradations</code>, which scales the luminance of each pixel.
   * </p>
   * @return {PostProcessStage} A post-process stage that renders the input texture with black and white gradations.
   */
  PostProcessStageLibrary.createBlackAndWhiteStage = function () {
    return new PostProcessStage({
      name: "czm_black_and_white",
      fragmentShader: BlackAndWhite,
      uniforms: {
        gradations: 5.0,
      },
    });
  };

  /**
   * Creates a post-process stage that saturates the input texture.
   * <p>
   * This stage has one uniform value, <code>brightness</code>, which scales the saturation of each pixel.
   * </p>
   * @return {PostProcessStage} A post-process stage that saturates the input texture.
   */
  PostProcessStageLibrary.createBrightnessStage = function () {
    return new PostProcessStage({
      name: "czm_brightness",
      fragmentShader: Brightness,
      uniforms: {
        brightness: 0.5,
      },
    });
  };

  /**
   * Creates a post-process stage that adds a night vision effect to the input texture.
   * @return {PostProcessStage} A post-process stage that adds a night vision effect to the input texture.
   */
  PostProcessStageLibrary.createNightVisionStage = function () {
    return new PostProcessStage({
      name: "czm_night_vision",
      fragmentShader: NightVision,
    });
  };

  /**
   * Creates a post-process stage that replaces the input color texture with a black and white texture representing the fragment depth at each pixel.
   * @return {PostProcessStage} A post-process stage that replaces the input color texture with a black and white texture representing the fragment depth at each pixel.
   *
   * @private
   */
  PostProcessStageLibrary.createDepthViewStage = function () {
    return new PostProcessStage({
      name: "czm_depth_view",
      fragmentShader: DepthView,
    });
  };

  /**
   * Creates a post-process stage that applies an effect simulating light flaring a camera lens.
   * <p>
   * This stage has the following uniforms: <code>dirtTexture</code>, <code>starTexture</code>, <code>intensity</code>, <code>distortion</code>, <code>ghostDispersal</code>,
   * <code>haloWidth</code>, <code>dirtAmount</code>, and <code>earthRadius</code>.
   * <ul>
   * <li><code>dirtTexture</code> is a texture sampled to simulate dirt on the lens.</li>
   * <li><code>starTexture</code> is the texture sampled for the star pattern of the flare.</li>
   * <li><code>intensity</code> is a scalar multiplied by the result of the lens flare. The default value is <code>2.0</code>.</li>
   * <li><code>distortion</code> is a scalar value that affects the chromatic effect distortion. The default value is <code>10.0</code>.</li>
   * <li><code>ghostDispersal</code> is a scalar indicating how far the halo effect is from the center of the texture. The default value is <code>0.4</code>.</li>
   * <li><code>haloWidth</code> is a scalar representing the width of the halo  from the ghost dispersal. The default value is <code>0.4</code>.</li>
   * <li><code>dirtAmount</code> is a scalar representing the amount of dirt on the lens. The default value is <code>0.4</code>.</li>
   * <li><code>earthRadius</code> is the maximum radius of the earth. The default value is <code>Ellipsoid.WGS84.maximumRadius</code>.</li>
   * </ul>
   * </p>
   * @return {PostProcessStage} A post-process stage for applying a lens flare effect.
   */
  PostProcessStageLibrary.createLensFlareStage = function () {
    return new PostProcessStage({
      name: "czm_lens_flare",
      fragmentShader: LensFlare,
      uniforms: {
        dirtTexture: buildModuleUrl("Assets/Textures/LensFlare/DirtMask.jpg"),
        starTexture: buildModuleUrl("Assets/Textures/LensFlare/StarBurst.jpg"),
        intensity: 2.0,
        distortion: 10.0,
        ghostDispersal: 0.4,
        haloWidth: 0.4,
        dirtAmount: 0.4,
        earthRadius: Ellipsoid.WGS84.maximumRadius,
      },
    });
  };

  /**
   * Creates a minimal amount of textures and framebuffers.
   *
   * @alias PostProcessStageTextureCache
   * @constructor
   *
   * @param {PostProcessStageCollection} postProcessStageCollection The post process collection.
   *
   * @private
   */
  function PostProcessStageTextureCache(postProcessStageCollection) {
    this._collection = postProcessStageCollection;

    this._framebuffers = [];
    this._stageNameToFramebuffer = {};

    this._width = undefined;
    this._height = undefined;
    this._updateDependencies = false;
  }

  function getLastStageName(stage) {
    while (defined(stage.length)) {
      stage = stage.get(stage.length - 1);
    }
    return stage.name;
  }

  function getStageDependencies(
    collection,
    context,
    dependencies,
    stage,
    previousName
  ) {
    if (!stage.enabled || !stage._isSupported(context)) {
      return previousName;
    }

    var stageDependencies = (dependencies[stage.name] = {});
    if (defined(previousName)) {
      var previous = collection.getStageByName(previousName);
      stageDependencies[getLastStageName(previous)] = true;
    }
    var uniforms = stage.uniforms;
    if (defined(uniforms)) {
      var uniformNames = Object.getOwnPropertyNames(uniforms);
      var uniformNamesLength = uniformNames.length;
      for (var i = 0; i < uniformNamesLength; ++i) {
        var value = uniforms[uniformNames[i]];
        if (typeof value === "string") {
          var dependent = collection.getStageByName(value);
          if (defined(dependent)) {
            stageDependencies[getLastStageName(dependent)] = true;
          }
        }
      }
    }

    return stage.name;
  }

  function getCompositeDependencies(
    collection,
    context,
    dependencies,
    composite,
    previousName
  ) {
    if (
      (defined(composite.enabled) && !composite.enabled) ||
      (defined(composite._isSupported) && !composite._isSupported(context))
    ) {
      return previousName;
    }

    var originalDependency = previousName;

    var inSeries =
      !defined(composite.inputPreviousStageTexture) ||
      composite.inputPreviousStageTexture;
    var currentName = previousName;
    var length = composite.length;
    for (var i = 0; i < length; ++i) {
      var stage = composite.get(i);
      if (defined(stage.length)) {
        currentName = getCompositeDependencies(
          collection,
          context,
          dependencies,
          stage,
          previousName
        );
      } else {
        currentName = getStageDependencies(
          collection,
          context,
          dependencies,
          stage,
          previousName
        );
      }
      // Stages in a series only depend on the previous stage
      if (inSeries) {
        previousName = currentName;
      }
    }

    // Stages not in a series depend on every stage executed before it since it could reference it as a uniform.
    // This prevents looking at the dependencies of each stage in the composite, but might create more framebuffers than necessary.
    // In practice, there are only 2-3 stages in these composites.
    var j;
    var name;
    if (!inSeries) {
      for (j = 1; j < length; ++j) {
        name = getLastStageName(composite.get(j));
        var currentDependencies = dependencies[name];
        for (var k = 0; k < j; ++k) {
          currentDependencies[getLastStageName(composite.get(k))] = true;
        }
      }
    } else {
      for (j = 1; j < length; ++j) {
        name = getLastStageName(composite.get(j));
        if (!defined(dependencies[name])) {
          dependencies[name] = {};
        }
        dependencies[name][originalDependency] = true;
      }
    }

    return currentName;
  }

  function getDependencies(collection, context) {
    var dependencies = {};

    if (defined(collection.ambientOcclusion)) {
      var ao = collection.ambientOcclusion;
      var bloom = collection.bloom;
      var tonemapping = collection._tonemapping;
      var fxaa = collection.fxaa;

      var previousName = getCompositeDependencies(
        collection,
        context,
        dependencies,
        ao,
        undefined
      );
      previousName = getCompositeDependencies(
        collection,
        context,
        dependencies,
        bloom,
        previousName
      );
      previousName = getStageDependencies(
        collection,
        context,
        dependencies,
        tonemapping,
        previousName
      );
      previousName = getCompositeDependencies(
        collection,
        context,
        dependencies,
        collection,
        previousName
      );
      getStageDependencies(collection, context, dependencies, fxaa, previousName);
    } else {
      getCompositeDependencies(
        collection,
        context,
        dependencies,
        collection,
        undefined
      );
    }

    return dependencies;
  }

  function getFramebuffer(cache, stageName, dependencies) {
    var collection = cache._collection;
    var stage = collection.getStageByName(stageName);

    var textureScale = stage._textureScale;
    var forcePowerOfTwo = stage._forcePowerOfTwo;
    var pixelFormat = stage._pixelFormat;
    var pixelDatatype = stage._pixelDatatype;
    var clearColor = stage._clearColor;

    var i;
    var framebuffer;
    var framebuffers = cache._framebuffers;
    var length = framebuffers.length;
    for (i = 0; i < length; ++i) {
      framebuffer = framebuffers[i];

      if (
        textureScale !== framebuffer.textureScale ||
        forcePowerOfTwo !== framebuffer.forcePowerOfTwo ||
        pixelFormat !== framebuffer.pixelFormat ||
        pixelDatatype !== framebuffer.pixelDatatype ||
        !Color.equals(clearColor, framebuffer.clearColor)
      ) {
        continue;
      }

      var stageNames = framebuffer.stages;
      var stagesLength = stageNames.length;
      var foundConflict = false;
      for (var j = 0; j < stagesLength; ++j) {
        if (dependencies[stageNames[j]]) {
          foundConflict = true;
          break;
        }
      }

      if (!foundConflict) {
        break;
      }
    }

    if (defined(framebuffer) && i < length) {
      framebuffer.stages.push(stageName);
      return framebuffer;
    }

    framebuffer = {
      textureScale: textureScale,
      forcePowerOfTwo: forcePowerOfTwo,
      pixelFormat: pixelFormat,
      pixelDatatype: pixelDatatype,
      clearColor: clearColor,
      stages: [stageName],
      buffer: undefined,
      clear: undefined,
    };

    framebuffers.push(framebuffer);
    return framebuffer;
  }

  function createFramebuffers$3(cache, context) {
    var dependencies = getDependencies(cache._collection, context);
    for (var stageName in dependencies) {
      if (dependencies.hasOwnProperty(stageName)) {
        cache._stageNameToFramebuffer[stageName] = getFramebuffer(
          cache,
          stageName,
          dependencies[stageName]
        );
      }
    }
  }

  function releaseResources$1(cache) {
    var framebuffers = cache._framebuffers;
    var length = framebuffers.length;
    for (var i = 0; i < length; ++i) {
      var framebuffer = framebuffers[i];
      framebuffer.buffer = framebuffer.buffer && framebuffer.buffer.destroy();
      framebuffer.buffer = undefined;
    }
  }

  function updateFramebuffers$3(cache, context) {
    var width = cache._width;
    var height = cache._height;

    var framebuffers = cache._framebuffers;
    var length = framebuffers.length;
    for (var i = 0; i < length; ++i) {
      var framebuffer = framebuffers[i];

      var scale = framebuffer.textureScale;
      var textureWidth = Math.ceil(width * scale);
      var textureHeight = Math.ceil(height * scale);

      var size = Math.min(textureWidth, textureHeight);
      if (framebuffer.forcePowerOfTwo) {
        if (!CesiumMath.isPowerOfTwo(size)) {
          size = CesiumMath.nextPowerOfTwo(size);
        }
        textureWidth = size;
        textureHeight = size;
      }

      framebuffer.buffer = new Framebuffer({
        context: context,
        colorTextures: [
          new Texture({
            context: context,
            width: textureWidth,
            height: textureHeight,
            pixelFormat: framebuffer.pixelFormat,
            pixelDatatype: framebuffer.pixelDatatype,
          }),
        ],
      });
      framebuffer.clear = new ClearCommand({
        color: framebuffer.clearColor,
        framebuffer: framebuffer.buffer,
      });
    }
  }

  PostProcessStageTextureCache.prototype.updateDependencies = function () {
    this._updateDependencies = true;
  };

  /**
   * Called before the stages in the collection are executed. Creates the minimum amount of framebuffers for a post-process collection.
   *
   * @param {Context} context The context.
   */
  PostProcessStageTextureCache.prototype.update = function (context) {
    var collection = this._collection;
    var updateDependencies = this._updateDependencies;
    var aoEnabled =
      defined(collection.ambientOcclusion) &&
      collection.ambientOcclusion.enabled &&
      collection.ambientOcclusion._isSupported(context);
    var bloomEnabled =
      defined(collection.bloom) &&
      collection.bloom.enabled &&
      collection.bloom._isSupported(context);
    var tonemappingEnabled =
      defined(collection._tonemapping) &&
      collection._tonemapping.enabled &&
      collection._tonemapping._isSupported(context);
    var fxaaEnabled =
      defined(collection.fxaa) &&
      collection.fxaa.enabled &&
      collection.fxaa._isSupported(context);
    var needsCheckDimensionsUpdate =
      !defined(collection._activeStages) ||
      collection._activeStages.length > 0 ||
      aoEnabled ||
      bloomEnabled ||
      tonemappingEnabled ||
      fxaaEnabled;
    if (
      updateDependencies ||
      (!needsCheckDimensionsUpdate && this._framebuffers.length > 0)
    ) {
      releaseResources$1(this);
      this._framebuffers.length = 0;
      this._stageNameToFramebuffer = {};
      this._width = undefined;
      this._height = undefined;
    }

    if (!updateDependencies && !needsCheckDimensionsUpdate) {
      return;
    }

    if (this._framebuffers.length === 0) {
      createFramebuffers$3(this, context);
    }

    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight;
    var dimensionsChanged = this._width !== width || this._height !== height;
    if (!updateDependencies && !dimensionsChanged) {
      return;
    }

    this._width = width;
    this._height = height;
    this._updateDependencies = false;
    releaseResources$1(this);
    updateFramebuffers$3(this, context);
  };

  /**
   * Clears all of the framebuffers.
   *
   * @param {Context} context The context.
   */
  PostProcessStageTextureCache.prototype.clear = function (context) {
    var framebuffers = this._framebuffers;
    for (var i = 0; i < framebuffers.length; ++i) {
      framebuffers[i].clear.execute(context);
    }
  };

  /**
   * Gets the stage with the given name.
   * @param {String} name The name of the stage.
   * @return {PostProcessStage|PostProcessStageComposite}
   */
  PostProcessStageTextureCache.prototype.getStageByName = function (name) {
    return this._collection.getStageByName(name);
  };

  /**
   * Gets the output texture for a stage with the given name.
   * @param {String} name The name of the stage.
   * @return {Texture|undefined} The output texture of the stage with the given name.
   */
  PostProcessStageTextureCache.prototype.getOutputTexture = function (name) {
    return this._collection.getOutputTexture(name);
  };

  /**
   * Gets the framebuffer for a stage with the given name.
   *
   * @param {String} name The name of the stage.
   * @return {Framebuffer|undefined} The framebuffer for the stage with the given name.
   */
  PostProcessStageTextureCache.prototype.getFramebuffer = function (name) {
    var framebuffer = this._stageNameToFramebuffer[name];
    if (!defined(framebuffer)) {
      return undefined;
    }
    return framebuffer.buffer;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PostProcessStageTextureCache#destroy
   */
  PostProcessStageTextureCache.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PostProcessStageTextureCache#isDestroyed
   */
  PostProcessStageTextureCache.prototype.destroy = function () {
    releaseResources$1(this);
    return destroyObject(this);
  };

  /**
   * A tonemapping algorithm when rendering with high dynamic range.
   *
   * @enum {Number}
   * @private
   */
  var Tonemapper = {
    /**
     * Use the Reinhard tonemapping operator.
     *
     * @type {Number}
     * @constant
     */
    REINHARD: 0,

    /**
     * Use the modified Reinhard tonemapping operator.
     *
     * @type {Number}
     * @constant
     */
    MODIFIED_REINHARD: 1,

    /**
     * Use the Filmic tonemapping operator.
     *
     * @type {Number}
     * @constant
     */
    FILMIC: 2,

    /**
     * Use the ACES tonemapping operator.
     *
     * @type {Number}
     * @constant
     */
    ACES: 3,

    /**
     * @private
     */
    validate: function (tonemapper) {
      return (
        tonemapper === Tonemapper.REINHARD ||
        tonemapper === Tonemapper.MODIFIED_REINHARD ||
        tonemapper === Tonemapper.FILMIC ||
        tonemapper === Tonemapper.ACES
      );
    },
  };
  var Tonemapper$1 = Object.freeze(Tonemapper);

  var stackScratch = [];

  /**
   * A collection of {@link PostProcessStage}s and/or {@link PostProcessStageComposite}s.
   * <p>
   * The input texture for each post-process stage is the texture rendered to by the scene or the texture rendered
   * to by the previous stage in the collection.
   * </p>
   * <p>
   * If the ambient occlusion or bloom stages are enabled, they will execute before all other stages.
   * </p>
   * <p>
   * If the FXAA stage is enabled, it will execute after all other stages.
   * </p>
   *
   * @alias PostProcessStageCollection
   * @constructor
   */
  function PostProcessStageCollection() {
    var fxaa = PostProcessStageLibrary.createFXAAStage();
    var ao = PostProcessStageLibrary.createAmbientOcclusionStage();
    var bloom = PostProcessStageLibrary.createBloomStage();

    // Auto-exposure is currently disabled because most shaders output a value in [0.0, 1.0].
    // Some shaders, such as the atmosphere and ground atmosphere, output values slightly over 1.0.
    this._autoExposureEnabled = false;
    this._autoExposure = PostProcessStageLibrary.createAutoExposureStage();
    this._tonemapping = undefined;
    this._tonemapper = undefined;

    // set tonemapper and tonemapping
    this.tonemapper = Tonemapper$1.ACES;

    var tonemapping = this._tonemapping;

    fxaa.enabled = false;
    ao.enabled = false;
    bloom.enabled = false;
    tonemapping.enabled = false; // will be enabled if necessary in update

    var textureCache = new PostProcessStageTextureCache(this);

    var stageNames = {};
    var stack = stackScratch;
    stack.push(fxaa, ao, bloom, tonemapping);
    while (stack.length > 0) {
      var stage = stack.pop();
      stageNames[stage.name] = stage;
      stage._textureCache = textureCache;

      var length = stage.length;
      if (defined(length)) {
        for (var i = 0; i < length; ++i) {
          stack.push(stage.get(i));
        }
      }
    }

    this._stages = [];
    this._activeStages = [];
    this._previousActiveStages = [];

    this._randomTexture = undefined; // For AO

    var that = this;
    ao.uniforms.randomTexture = function () {
      return that._randomTexture;
    };

    this._ao = ao;
    this._bloom = bloom;
    this._fxaa = fxaa;

    this._lastLength = undefined;
    this._aoEnabled = undefined;
    this._bloomEnabled = undefined;
    this._tonemappingEnabled = undefined;
    this._fxaaEnabled = undefined;

    this._stagesRemoved = false;
    this._textureCacheDirty = false;

    this._stageNames = stageNames;
    this._textureCache = textureCache;
  }

  Object.defineProperties(PostProcessStageCollection.prototype, {
    /**
     * Determines if all of the post-process stages in the collection are ready to be executed.
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        var readyAndEnabled = false;
        var stages = this._stages;
        var length = stages.length;
        for (var i = length - 1; i >= 0; --i) {
          var stage = stages[i];
          readyAndEnabled = readyAndEnabled || (stage.ready && stage.enabled);
        }

        var fxaa = this._fxaa;
        var ao = this._ao;
        var bloom = this._bloom;
        var tonemapping = this._tonemapping;

        readyAndEnabled = readyAndEnabled || (fxaa.ready && fxaa.enabled);
        readyAndEnabled = readyAndEnabled || (ao.ready && ao.enabled);
        readyAndEnabled = readyAndEnabled || (bloom.ready && bloom.enabled);
        readyAndEnabled =
          readyAndEnabled || (tonemapping.ready && tonemapping.enabled);

        return readyAndEnabled;
      },
    },
    /**
     * A post-process stage for Fast Approximate Anti-aliasing.
     * <p>
     * When enabled, this stage will execute after all others.
     * </p>
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {PostProcessStage}
     * @readonly
     */
    fxaa: {
      get: function () {
        return this._fxaa;
      },
    },
    /**
     * A post-process stage that applies Horizon-based Ambient Occlusion (HBAO) to the input texture.
     * <p>
     * Ambient occlusion simulates shadows from ambient light. These shadows would always be present when the
     * surface receives light and regardless of the light's position.
     * </p>
     * <p>
     * The uniforms have the following properties: <code>intensity</code>, <code>bias</code>, <code>lengthCap</code>,
     * <code>stepSize</code>, <code>frustumLength</code>, <code>ambientOcclusionOnly</code>,
     * <code>delta</code>, <code>sigma</code>, and <code>blurStepSize</code>.
     * </p>
     * <ul>
     * <li><code>intensity</code> is a scalar value used to lighten or darken the shadows exponentially. Higher values make the shadows darker. The default value is <code>3.0</code>.</li>
     *
     * <li><code>bias</code> is a scalar value representing an angle in radians. If the dot product between the normal of the sample and the vector to the camera is less than this value,
     * sampling stops in the current direction. This is used to remove shadows from near planar edges. The default value is <code>0.1</code>.</li>
     *
     * <li><code>lengthCap</code> is a scalar value representing a length in meters. If the distance from the current sample to first sample is greater than this value,
     * sampling stops in the current direction. The default value is <code>0.26</code>.</li>
     *
     * <li><code>stepSize</code> is a scalar value indicating the distance to the next texel sample in the current direction. The default value is <code>1.95</code>.</li>
     *
     * <li><code>frustumLength</code> is a scalar value in meters. If the current fragment has a distance from the camera greater than this value, ambient occlusion is not computed for the fragment.
     * The default value is <code>1000.0</code>.</li>
     *
     * <li><code>ambientOcclusionOnly</code> is a boolean value. When <code>true</code>, only the shadows generated are written to the output. When <code>false</code>, the input texture is modulated
     * with the ambient occlusion. This is a useful debug option for seeing the effects of changing the uniform values. The default value is <code>false</code>.</li>
     * </ul>
     * <p>
     * <code>delta</code>, <code>sigma</code>, and <code>blurStepSize</code> are the same properties as {@link PostProcessStageLibrary#createBlurStage}.
     * The blur is applied to the shadows generated from the image to make them smoother.
     * </p>
     * <p>
     * When enabled, this stage will execute before all others.
     * </p>
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {PostProcessStageComposite}
     * @readonly
     */
    ambientOcclusion: {
      get: function () {
        return this._ao;
      },
    },
    /**
     * A post-process stage for a bloom effect.
     * <p>
     * A bloom effect adds glow effect, makes bright areas brighter, and dark areas darker.
     * </p>
     * <p>
     * This stage has the following uniforms: <code>contrast</code>, <code>brightness</code>, <code>glowOnly</code>,
     * <code>delta</code>, <code>sigma</code>, and <code>stepSize</code>.
     * </p>
     * <ul>
     * <li><code>contrast</code> is a scalar value in the range [-255.0, 255.0] and affects the contract of the effect. The default value is <code>128.0</code>.</li>
     *
     * <li><code>brightness</code> is a scalar value. The input texture RGB value is converted to hue, saturation, and brightness (HSB) then this value is
     * added to the brightness. The default value is <code>-0.3</code>.</li>
     *
     * <li><code>glowOnly</code> is a boolean value. When <code>true</code>, only the glow effect will be shown. When <code>false</code>, the glow will be added to the input texture.
     * The default value is <code>false</code>. This is a debug option for viewing the effects when changing the other uniform values.</li>
     * </ul>
     * <p>
     * <code>delta</code>, <code>sigma</code>, and <code>stepSize</code> are the same properties as {@link PostProcessStageLibrary#createBlurStage}.
     * The blur is applied to the shadows generated from the image to make them smoother.
     * </p>
     * <p>
     * When enabled, this stage will execute before all others.
     * </p>
     *
     * @memberOf PostProcessStageCollection.prototype
     * @type {PostProcessStageComposite}
     * @readonly
     */
    bloom: {
      get: function () {
        return this._bloom;
      },
    },
    /**
     * The number of post-process stages in this collection.
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        removeStages(this);
        return this._stages.length;
      },
    },
    /**
     * A reference to the last texture written to when executing the post-process stages in this collection.
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {Texture}
     * @readonly
     * @private
     */
    outputTexture: {
      get: function () {
        var fxaa = this._fxaa;
        if (fxaa.enabled && fxaa.ready) {
          return this.getOutputTexture(fxaa.name);
        }

        var stages = this._stages;
        var length = stages.length;
        for (var i = length - 1; i >= 0; --i) {
          var stage = stages[i];
          if (defined(stage) && stage.ready && stage.enabled) {
            return this.getOutputTexture(stage.name);
          }
        }

        var tonemapping = this._tonemapping;
        if (tonemapping.enabled && tonemapping.ready) {
          return this.getOutputTexture(tonemapping.name);
        }

        var bloom = this._bloom;
        if (bloom.enabled && bloom.ready) {
          return this.getOutputTexture(bloom.name);
        }

        var ao = this._ao;
        if (ao.enabled && ao.ready) {
          return this.getOutputTexture(ao.name);
        }

        return undefined;
      },
    },
    /**
     * Whether the collection has a stage that has selected features.
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {Boolean}
     * @readonly
     * @private
     */
    hasSelected: {
      get: function () {
        var stages = arraySlice(this._stages);
        while (stages.length > 0) {
          var stage = stages.pop();
          if (!defined(stage)) {
            continue;
          }
          if (defined(stage.selected)) {
            return true;
          }
          var length = stage.length;
          if (defined(length)) {
            for (var i = 0; i < length; ++i) {
              stages.push(stage.get(i));
            }
          }
        }
        return false;
      },
    },
    /**
     * Gets and sets the tonemapping algorithm used when rendering with high dynamic range.
     *
     * @memberof PostProcessStageCollection.prototype
     * @type {Tonemapper}
     * @private
     */
    tonemapper: {
      get: function () {
        return this._tonemapper;
      },
      set: function (value) {
        if (this._tonemapper === value) {
          return;
        }
        //>>includeStart('debug', pragmas.debug);
        if (!Tonemapper$1.validate(value)) {
          throw new DeveloperError("tonemapper was set to an invalid value.");
        }
        //>>includeEnd('debug');

        if (defined(this._tonemapping)) {
          delete this._stageNames[this._tonemapping.name];
          this._tonemapping.destroy();
        }

        var useAutoExposure = this._autoExposureEnabled;
        var tonemapper;

        switch (value) {
          case Tonemapper$1.REINHARD:
            tonemapper = PostProcessStageLibrary.createReinhardTonemappingStage(
              useAutoExposure
            );
            break;
          case Tonemapper$1.MODIFIED_REINHARD:
            tonemapper = PostProcessStageLibrary.createModifiedReinhardTonemappingStage(
              useAutoExposure
            );
            break;
          case Tonemapper$1.FILMIC:
            tonemapper = PostProcessStageLibrary.createFilmicTonemappingStage(
              useAutoExposure
            );
            break;
          default:
            tonemapper = PostProcessStageLibrary.createAcesTonemappingStage(
              useAutoExposure
            );
            break;
        }

        if (useAutoExposure) {
          var autoexposure = this._autoExposure;
          tonemapper.uniforms.autoExposure = function () {
            return autoexposure.outputTexture;
          };
        }

        this._tonemapper = value;
        this._tonemapping = tonemapper;

        if (defined(this._stageNames)) {
          this._stageNames[tonemapper.name] = tonemapper;
          tonemapper._textureCache = this._textureCache;
        }

        this._textureCacheDirty = true;
      },
    },
  });

  function removeStages(collection) {
    if (!collection._stagesRemoved) {
      return;
    }

    collection._stagesRemoved = false;

    var newStages = [];
    var stages = collection._stages;
    var length = stages.length;
    for (var i = 0, j = 0; i < length; ++i) {
      var stage = stages[i];
      if (stage) {
        stage._index = j++;
        newStages.push(stage);
      }
    }

    collection._stages = newStages;
  }

  /**
   * Adds the post-process stage to the collection.
   *
   * @param {PostProcessStage|PostProcessStageComposite} stage The post-process stage to add to the collection.
   * @return {PostProcessStage|PostProcessStageComposite} The post-process stage that was added to the collection.
   *
   * @exception {DeveloperError} The post-process stage has already been added to the collection or does not have a unique name.
   */
  PostProcessStageCollection.prototype.add = function (stage) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("stage", stage);
    //>>includeEnd('debug');

    var stageNames = this._stageNames;

    var stack = stackScratch;
    stack.push(stage);
    while (stack.length > 0) {
      var currentStage = stack.pop();
      //>>includeStart('debug', pragmas.debug);
      if (defined(stageNames[currentStage.name])) {
        throw new DeveloperError(
          currentStage.name +
            " has already been added to the collection or does not have a unique name."
        );
      }
      //>>includeEnd('debug');
      stageNames[currentStage.name] = currentStage;
      currentStage._textureCache = this._textureCache;

      var length = currentStage.length;
      if (defined(length)) {
        for (var i = 0; i < length; ++i) {
          stack.push(currentStage.get(i));
        }
      }
    }

    var stages = this._stages;
    stage._index = stages.length;
    stages.push(stage);
    this._textureCacheDirty = true;
    return stage;
  };

  /**
   * Removes a post-process stage from the collection and destroys it.
   *
   * @param {PostProcessStage|PostProcessStageComposite} stage The post-process stage to remove from the collection.
   * @return {Boolean} Whether the post-process stage was removed.
   */
  PostProcessStageCollection.prototype.remove = function (stage) {
    if (!this.contains(stage)) {
      return false;
    }

    var stageNames = this._stageNames;

    var stack = stackScratch;
    stack.push(stage);
    while (stack.length > 0) {
      var currentStage = stack.pop();
      delete stageNames[currentStage.name];

      var length = currentStage.length;
      if (defined(length)) {
        for (var i = 0; i < length; ++i) {
          stack.push(currentStage.get(i));
        }
      }
    }

    this._stages[stage._index] = undefined;
    this._stagesRemoved = true;
    this._textureCacheDirty = true;
    stage._index = undefined;
    stage._textureCache = undefined;
    stage.destroy();
    return true;
  };

  /**
   * Returns whether the collection contains a post-process stage.
   *
   * @param {PostProcessStage|PostProcessStageComposite} stage The post-process stage.
   * @return {Boolean} Whether the collection contains the post-process stage.
   */
  PostProcessStageCollection.prototype.contains = function (stage) {
    return (
      defined(stage) &&
      defined(stage._index) &&
      stage._textureCache === this._textureCache
    );
  };

  /**
   * Gets the post-process stage at <code>index</code>.
   *
   * @param {Number} index The index of the post-process stage.
   * @return {PostProcessStage|PostProcessStageComposite} The post-process stage at index.
   */
  PostProcessStageCollection.prototype.get = function (index) {
    removeStages(this);
    var stages = this._stages;
    //>>includeStart('debug', pragmas.debug);
    var length = stages.length;
    Check.typeOf.number.greaterThanOrEquals("stages length", length, 0);
    Check.typeOf.number.greaterThanOrEquals("index", index, 0);
    Check.typeOf.number.lessThan("index", index, length);
    //>>includeEnd('debug');
    return stages[index];
  };

  /**
   * Removes all post-process stages from the collection and destroys them.
   */
  PostProcessStageCollection.prototype.removeAll = function () {
    var stages = this._stages;
    var length = stages.length;
    for (var i = 0; i < length; ++i) {
      this.remove(stages[i]);
    }
    stages.length = 0;
  };

  /**
   * Gets a post-process stage in the collection by its name.
   *
   * @param {String} name The name of the post-process stage.
   * @return {PostProcessStage|PostProcessStageComposite} The post-process stage.
   *
   * @private
   */
  PostProcessStageCollection.prototype.getStageByName = function (name) {
    return this._stageNames[name];
  };

  /**
   * Called before the post-process stages in the collection are executed. Calls update for each stage and creates WebGL resources.
   *
   * @param {Context} context The context.
   * @param {Boolean} useLogDepth Whether the scene uses a logarithmic depth buffer.
   *
   * @private
   */
  PostProcessStageCollection.prototype.update = function (
    context,
    useLogDepth,
    useHdr
  ) {
    removeStages(this);

    var previousActiveStages = this._activeStages;
    var activeStages = (this._activeStages = this._previousActiveStages);
    this._previousActiveStages = previousActiveStages;

    var stages = this._stages;
    var length = (activeStages.length = stages.length);

    var i;
    var stage;
    var count = 0;
    for (i = 0; i < length; ++i) {
      stage = stages[i];
      if (stage.ready && stage.enabled && stage._isSupported(context)) {
        activeStages[count++] = stage;
      }
    }
    activeStages.length = count;

    var activeStagesChanged = count !== previousActiveStages.length;
    if (!activeStagesChanged) {
      for (i = 0; i < count; ++i) {
        if (activeStages[i] !== previousActiveStages[i]) {
          activeStagesChanged = true;
          break;
        }
      }
    }

    var ao = this._ao;
    var bloom = this._bloom;
    var autoexposure = this._autoExposure;
    var tonemapping = this._tonemapping;
    var fxaa = this._fxaa;

    tonemapping.enabled = useHdr;

    var aoEnabled = ao.enabled && ao._isSupported(context);
    var bloomEnabled = bloom.enabled && bloom._isSupported(context);
    var tonemappingEnabled =
      tonemapping.enabled && tonemapping._isSupported(context);
    var fxaaEnabled = fxaa.enabled && fxaa._isSupported(context);

    if (
      activeStagesChanged ||
      this._textureCacheDirty ||
      count !== this._lastLength ||
      aoEnabled !== this._aoEnabled ||
      bloomEnabled !== this._bloomEnabled ||
      tonemappingEnabled !== this._tonemappingEnabled ||
      fxaaEnabled !== this._fxaaEnabled
    ) {
      // The number of stages to execute has changed.
      // Update dependencies and recreate framebuffers.
      this._textureCache.updateDependencies();

      this._lastLength = count;
      this._aoEnabled = aoEnabled;
      this._bloomEnabled = bloomEnabled;
      this._tonemappingEnabled = tonemappingEnabled;
      this._fxaaEnabled = fxaaEnabled;
      this._textureCacheDirty = false;
    }

    if (defined(this._randomTexture) && !aoEnabled) {
      this._randomTexture.destroy();
      this._randomTexture = undefined;
    }

    if (!defined(this._randomTexture) && aoEnabled) {
      length = 256 * 256 * 3;
      var random = new Uint8Array(length);
      for (i = 0; i < length; i += 3) {
        random[i] = Math.floor(Math.random() * 255.0);
      }

      this._randomTexture = new Texture({
        context: context,
        pixelFormat: PixelFormat$1.RGB,
        pixelDatatype: PixelDatatype$1.UNSIGNED_BYTE,
        source: {
          arrayBufferView: random,
          width: 256,
          height: 256,
        },
        sampler: new Sampler({
          wrapS: TextureWrap$1.REPEAT,
          wrapT: TextureWrap$1.REPEAT,
          minificationFilter: TextureMinificationFilter$1.NEAREST,
          magnificationFilter: TextureMagnificationFilter$1.NEAREST,
        }),
      });
    }

    this._textureCache.update(context);

    fxaa.update(context, useLogDepth);
    ao.update(context, useLogDepth);
    bloom.update(context, useLogDepth);
    tonemapping.update(context, useLogDepth);

    if (this._autoExposureEnabled) {
      autoexposure.update(context, useLogDepth);
    }

    length = stages.length;
    for (i = 0; i < length; ++i) {
      stages[i].update(context, useLogDepth);
    }
  };

  /**
   * Clears all of the framebuffers used by the stages.
   *
   * @param {Context} context The context.
   *
   * @private
   */
  PostProcessStageCollection.prototype.clear = function (context) {
    this._textureCache.clear(context);

    if (this._autoExposureEnabled) {
      this._autoExposure.clear(context);
    }
  };

  function getOutputTexture(stage) {
    while (defined(stage.length)) {
      stage = stage.get(stage.length - 1);
    }
    return stage.outputTexture;
  }

  /**
   * Gets the output texture of a stage with the given name.
   *
   * @param {String} stageName The name of the stage.
   * @return {Texture|undefined} The texture rendered to by the stage with the given name.
   *
   * @private
   */
  PostProcessStageCollection.prototype.getOutputTexture = function (stageName) {
    var stage = this.getStageByName(stageName);
    if (!defined(stage)) {
      return undefined;
    }
    return getOutputTexture(stage);
  };

  function execute(stage, context, colorTexture, depthTexture, idTexture) {
    if (defined(stage.execute)) {
      stage.execute(context, colorTexture, depthTexture, idTexture);
      return;
    }

    var length = stage.length;
    var i;

    if (stage.inputPreviousStageTexture) {
      execute(stage.get(0), context, colorTexture, depthTexture, idTexture);
      for (i = 1; i < length; ++i) {
        execute(
          stage.get(i),
          context,
          getOutputTexture(stage.get(i - 1)),
          depthTexture,
          idTexture
        );
      }
    } else {
      for (i = 0; i < length; ++i) {
        execute(stage.get(i), context, colorTexture, depthTexture, idTexture);
      }
    }
  }

  /**
   * Executes all ready and enabled stages in the collection.
   *
   * @param {Context} context The context.
   * @param {Texture} colorTexture The color texture rendered to by the scene.
   * @param {Texture} depthTexture The depth texture written to by the scene.
   * @param {Texture} idTexture The id texture written to by the scene.
   *
   * @private
   */
  PostProcessStageCollection.prototype.execute = function (
    context,
    colorTexture,
    depthTexture,
    idTexture
  ) {
    var activeStages = this._activeStages;
    var length = activeStages.length;

    var fxaa = this._fxaa;
    var ao = this._ao;
    var bloom = this._bloom;
    var autoexposure = this._autoExposure;
    var tonemapping = this._tonemapping;

    var aoEnabled = ao.enabled && ao._isSupported(context);
    var bloomEnabled = bloom.enabled && bloom._isSupported(context);
    var autoExposureEnabled = this._autoExposureEnabled;
    var tonemappingEnabled =
      tonemapping.enabled && tonemapping._isSupported(context);
    var fxaaEnabled = fxaa.enabled && fxaa._isSupported(context);

    if (
      !fxaaEnabled &&
      !aoEnabled &&
      !bloomEnabled &&
      !tonemappingEnabled &&
      length === 0
    ) {
      return;
    }

    var initialTexture = colorTexture;
    if (aoEnabled && ao.ready) {
      execute(ao, context, initialTexture, depthTexture, idTexture);
      initialTexture = getOutputTexture(ao);
    }
    if (bloomEnabled && bloom.ready) {
      execute(bloom, context, initialTexture, depthTexture, idTexture);
      initialTexture = getOutputTexture(bloom);
    }
    if (autoExposureEnabled && autoexposure.ready) {
      execute(autoexposure, context, initialTexture, depthTexture, idTexture);
    }
    if (tonemappingEnabled && tonemapping.ready) {
      execute(tonemapping, context, initialTexture, depthTexture, idTexture);
      initialTexture = getOutputTexture(tonemapping);
    }

    var lastTexture = initialTexture;

    if (length > 0) {
      execute(activeStages[0], context, initialTexture, depthTexture, idTexture);
      for (var i = 1; i < length; ++i) {
        execute(
          activeStages[i],
          context,
          getOutputTexture(activeStages[i - 1]),
          depthTexture,
          idTexture
        );
      }
      lastTexture = getOutputTexture(activeStages[length - 1]);
    }

    if (fxaaEnabled && fxaa.ready) {
      execute(fxaa, context, lastTexture, depthTexture, idTexture);
    }
  };

  /**
   * Copies the output of all executed stages to the color texture of a framebuffer.
   *
   * @param {Context} context The context.
   * @param {Framebuffer} framebuffer The framebuffer to copy to.
   *
   * @private
   */
  PostProcessStageCollection.prototype.copy = function (context, framebuffer) {
    if (!defined(this._copyColorCommand)) {
      var that = this;
      this._copyColorCommand = context.createViewportQuadCommand(PassThrough, {
        uniformMap: {
          colorTexture: function () {
            return that.outputTexture;
          },
        },
        owner: this,
      });
    }

    this._copyColorCommand.framebuffer = framebuffer;
    this._copyColorCommand.execute(context);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <p>
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   * </p>
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see PostProcessStageCollection#destroy
   */
  PostProcessStageCollection.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <p>
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   * </p>
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @see PostProcessStageCollection#isDestroyed
   */
  PostProcessStageCollection.prototype.destroy = function () {
    this._fxaa.destroy();
    this._ao.destroy();
    this._bloom.destroy();
    this._autoExposure.destroy();
    this._tonemapping.destroy();
    this.removeAll();
    this._textureCache = this._textureCache && this._textureCache.destroy();
    return destroyObject(this);
  };

  /**
   * Provides general quadtree tiles to be displayed on or near the surface of an ellipsoid.  It is intended to be
   * used with the {@link QuadtreePrimitive}.  This type describes an interface and is not intended to be
   * instantiated directly.
   *
   * @alias QuadtreeTileProvider
   * @constructor
   * @private
   */
  function QuadtreeTileProvider() {
    DeveloperError.throwInstantiationError();
  }

  /**
   * Computes the default geometric error for level zero of the quadtree.
   *
   * @memberof QuadtreeTileProvider
   *
   * @param {TilingScheme} tilingScheme The tiling scheme for which to compute the geometric error.
   * @returns {Number} The maximum geometric error at level zero, in meters.
   */
  QuadtreeTileProvider.computeDefaultLevelZeroMaximumGeometricError = function (
    tilingScheme
  ) {
    return (
      (tilingScheme.ellipsoid.maximumRadius * 2 * Math.PI * 0.25) /
      (65 * tilingScheme.getNumberOfXTilesAtLevel(0))
    );
  };

  Object.defineProperties(QuadtreeTileProvider.prototype, {
    /**
     * Gets or sets the {@link QuadtreePrimitive} for which this provider is
     * providing tiles.
     * @memberof QuadtreeTileProvider.prototype
     * @type {QuadtreePrimitive}
     */
    quadtree: {
      get: DeveloperError.throwInstantiationError,
      set: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof QuadtreeTileProvider.prototype
     * @type {Boolean}
     */
    ready: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets the tiling scheme used by the provider.  This property should
     * not be accessed before {@link QuadtreeTileProvider#ready} returns true.
     * @memberof QuadtreeTileProvider.prototype
     * @type {TilingScheme}
     */
    tilingScheme: {
      get: DeveloperError.throwInstantiationError,
    },

    /**
     * Gets an event that is raised when the geometry provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof QuadtreeTileProvider.prototype
     * @type {Event}
     */
    errorEvent: {
      get: DeveloperError.throwInstantiationError,
    },
  });

  /**
   * Called at the beginning of the update cycle, regardless of id a new frame is being rendered, before {@link QuadtreeTileProvider#beginUpdate}
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {Context} context The rendering context.
   * @param {FrameState} frameState The frame state.
   */
  QuadtreeTileProvider.prototype.update = DeveloperError.throwInstantiationError;

  /**
   * Called at the beginning of the update cycle for each render frame, before {@link QuadtreeTileProvider#showTileThisFrame}
   * or any other functions.
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {Context} context The rendering context.
   * @param {FrameState} frameState The frame state.
   * @param {DrawCommand[]} commandList An array of rendering commands.  This method may push
   *        commands into this array.
   */
  QuadtreeTileProvider.prototype.beginUpdate =
    DeveloperError.throwInstantiationError;

  /**
   * Called at the end of the update cycle for each render frame, after {@link QuadtreeTileProvider#showTileThisFrame}
   * and any other functions.
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {Context} context The rendering context.
   * @param {FrameState} frameState The frame state.
   * @param {DrawCommand[]} commandList An array of rendering commands.  This method may push
   *        commands into this array.
   */
  QuadtreeTileProvider.prototype.endUpdate =
    DeveloperError.throwInstantiationError;

  /**
   * Gets the maximum geometric error allowed in a tile at a given level, in meters.  This function should not be
   * called before {@link QuadtreeTileProvider#ready} returns true.
   *
   * @see QuadtreeTileProvider#computeDefaultLevelZeroMaximumGeometricError
   *
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {Number} level The tile level for which to get the maximum geometric error.
   * @returns {Number} The maximum geometric error in meters.
   */
  QuadtreeTileProvider.prototype.getLevelMaximumGeometricError =
    DeveloperError.throwInstantiationError;

  /**
   * Loads, or continues loading, a given tile.  This function will continue to be called
   * until {@link QuadtreeTile#state} is no longer {@link QuadtreeTileLoadState#LOADING}.  This function should
   * not be called before {@link QuadtreeTileProvider#ready} returns true.
   *
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {Context} context The rendering context.
   * @param {FrameState} frameState The frame state.
   * @param {QuadtreeTile} tile The tile to load.
   *
   * @exception {DeveloperError} <code>loadTile</code> must not be called before the tile provider is ready.
   */
  QuadtreeTileProvider.prototype.loadTile =
    DeveloperError.throwInstantiationError;

  /**
   * Determines the visibility of a given tile.  The tile may be fully visible, partially visible, or not
   * visible at all.  Tiles that are renderable and are at least partially visible will be shown by a call
   * to {@link QuadtreeTileProvider#showTileThisFrame}.
   *
   * @memberof QuadtreeTileProvider
   *
   * @param {QuadtreeTile} tile The tile instance.
   * @param {FrameState} frameState The state information about the current frame.
   * @param {QuadtreeOccluders} occluders The objects that may occlude this tile.
   *
   * @returns {Visibility} The visibility of the tile.
   */
  QuadtreeTileProvider.prototype.computeTileVisibility =
    DeveloperError.throwInstantiationError;

  /**
   * Shows a specified tile in this frame.  The provider can cause the tile to be shown by adding
   * render commands to the commandList, or use any other method as appropriate.  The tile is not
   * expected to be visible next frame as well, unless this method is call next frame, too.
   *
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {QuadtreeTile} tile The tile instance.
   * @param {Context} context The rendering context.
   * @param {FrameState} frameState The state information of the current rendering frame.
   * @param {DrawCommand[]} commandList The list of rendering commands.  This method may add additional commands to this list.
   */
  QuadtreeTileProvider.prototype.showTileThisFrame =
    DeveloperError.throwInstantiationError;

  /**
   * Gets the distance from the camera to the closest point on the tile.  This is used for level-of-detail selection.
   *
   * @memberof QuadtreeTileProvider
   * @function
   *
   * @param {QuadtreeTile} tile The tile instance.
   * @param {FrameState} frameState The state information of the current rendering frame.
   *
   * @returns {Number} The distance from the camera to the closest point on the tile, in meters.
   */
  QuadtreeTileProvider.prototype.computeDistanceToTile =
    DeveloperError.throwInstantiationError;

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @memberof QuadtreeTileProvider
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see QuadtreeTileProvider#destroy
   */
  QuadtreeTileProvider.prototype.isDestroyed =
    DeveloperError.throwInstantiationError;

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @memberof QuadtreeTileProvider
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * provider = provider && provider();
   *
   * @see QuadtreeTileProvider#isDestroyed
   */
  QuadtreeTileProvider.prototype.destroy = DeveloperError.throwInstantiationError;

  /**
   * @private
   */
  function SceneTransitioner(scene) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("scene", scene);
    //>>includeEnd('debug');

    this._scene = scene;
    this._currentTweens = [];
    this._morphHandler = undefined;
    this._morphCancelled = false;
    this._completeMorph = undefined;
    this._morphToOrthographic = false;
  }

  SceneTransitioner.prototype.completeMorph = function () {
    if (defined(this._completeMorph)) {
      this._completeMorph();
    }
  };

  SceneTransitioner.prototype.morphTo2D = function (duration, ellipsoid) {
    if (defined(this._completeMorph)) {
      this._completeMorph();
    }

    var scene = this._scene;
    this._previousMode = scene.mode;
    this._morphToOrthographic =
      scene.camera.frustum instanceof OrthographicFrustum;

    if (
      this._previousMode === SceneMode$1.SCENE2D ||
      this._previousMode === SceneMode$1.MORPHING
    ) {
      return;
    }
    this._scene.morphStart.raiseEvent(
      this,
      this._previousMode,
      SceneMode$1.SCENE2D,
      true
    );

    scene._mode = SceneMode$1.MORPHING;
    scene.camera._setTransform(Matrix4.IDENTITY);

    if (this._previousMode === SceneMode$1.COLUMBUS_VIEW) {
      morphFromColumbusViewTo2D(this, duration);
    } else {
      morphFrom3DTo2D(this, duration, ellipsoid);
    }

    if (duration === 0.0 && defined(this._completeMorph)) {
      this._completeMorph();
    }
  };

  var scratchToCVPosition = new Cartesian3();
  var scratchToCVDirection = new Cartesian3();
  var scratchToCVUp = new Cartesian3();
  var scratchToCVPosition2D = new Cartesian3();
  var scratchToCVDirection2D = new Cartesian3();
  var scratchToCVUp2D = new Cartesian3();
  var scratchToCVSurfacePosition = new Cartesian3();
  var scratchToCVCartographic = new Cartographic();
  var scratchToCVToENU = new Matrix4();
  var scratchToCVFrustumPerspective = new PerspectiveFrustum();
  var scratchToCVFrustumOrthographic = new OrthographicFrustum();
  var scratchToCVCamera = {
    position: undefined,
    direction: undefined,
    up: undefined,
    position2D: undefined,
    direction2D: undefined,
    up2D: undefined,
    frustum: undefined,
  };

  SceneTransitioner.prototype.morphToColumbusView = function (
    duration,
    ellipsoid
  ) {
    if (defined(this._completeMorph)) {
      this._completeMorph();
    }

    var scene = this._scene;
    this._previousMode = scene.mode;

    if (
      this._previousMode === SceneMode$1.COLUMBUS_VIEW ||
      this._previousMode === SceneMode$1.MORPHING
    ) {
      return;
    }
    this._scene.morphStart.raiseEvent(
      this,
      this._previousMode,
      SceneMode$1.COLUMBUS_VIEW,
      true
    );

    scene.camera._setTransform(Matrix4.IDENTITY);

    var position = scratchToCVPosition;
    var direction = scratchToCVDirection;
    var up = scratchToCVUp;

    if (duration > 0.0) {
      position.x = 0.0;
      position.y = -1.0;
      position.z = 1.0;
      position = Cartesian3.multiplyByScalar(
        Cartesian3.normalize(position, position),
        5.0 * ellipsoid.maximumRadius,
        position
      );

      Cartesian3.negate(Cartesian3.normalize(position, direction), direction);
      Cartesian3.cross(Cartesian3.UNIT_X, direction, up);
    } else {
      var camera = scene.camera;
      if (this._previousMode === SceneMode$1.SCENE2D) {
        Cartesian3.clone(camera.position, position);
        position.z = camera.frustum.right - camera.frustum.left;
        Cartesian3.negate(Cartesian3.UNIT_Z, direction);
        Cartesian3.clone(Cartesian3.UNIT_Y, up);
      } else {
        Cartesian3.clone(camera.positionWC, position);
        Cartesian3.clone(camera.directionWC, direction);
        Cartesian3.clone(camera.upWC, up);

        var surfacePoint = ellipsoid.scaleToGeodeticSurface(
          position,
          scratchToCVSurfacePosition
        );
        var toENU = Transforms.eastNorthUpToFixedFrame(
          surfacePoint,
          ellipsoid,
          scratchToCVToENU
        );
        Matrix4.inverseTransformation(toENU, toENU);

        scene.mapProjection.project(
          ellipsoid.cartesianToCartographic(position, scratchToCVCartographic),
          position
        );
        Matrix4.multiplyByPointAsVector(toENU, direction, direction);
        Matrix4.multiplyByPointAsVector(toENU, up, up);
      }
    }

    var frustum;
    if (this._morphToOrthographic) {
      frustum = scratchToCVFrustumOrthographic;
      frustum.width = scene.camera.frustum.right - scene.camera.frustum.left;
      frustum.aspectRatio = scene.drawingBufferWidth / scene.drawingBufferHeight;
    } else {
      frustum = scratchToCVFrustumPerspective;
      frustum.aspectRatio = scene.drawingBufferWidth / scene.drawingBufferHeight;
      frustum.fov = CesiumMath.toRadians(60.0);
    }

    var cameraCV = scratchToCVCamera;
    cameraCV.position = position;
    cameraCV.direction = direction;
    cameraCV.up = up;
    cameraCV.frustum = frustum;

    var complete = completeColumbusViewCallback(cameraCV);
    createMorphHandler(this, complete);

    if (this._previousMode === SceneMode$1.SCENE2D) {
      morphFrom2DToColumbusView(this, duration, cameraCV, complete);
    } else {
      cameraCV.position2D = Matrix4.multiplyByPoint(
        Camera.TRANSFORM_2D,
        position,
        scratchToCVPosition2D
      );
      cameraCV.direction2D = Matrix4.multiplyByPointAsVector(
        Camera.TRANSFORM_2D,
        direction,
        scratchToCVDirection2D
      );
      cameraCV.up2D = Matrix4.multiplyByPointAsVector(
        Camera.TRANSFORM_2D,
        up,
        scratchToCVUp2D
      );

      scene._mode = SceneMode$1.MORPHING;
      morphFrom3DToColumbusView(this, duration, cameraCV, complete);
    }

    if (duration === 0.0 && defined(this._completeMorph)) {
      this._completeMorph();
    }
  };

  var scratchCVTo3DCamera = {
    position: new Cartesian3(),
    direction: new Cartesian3(),
    up: new Cartesian3(),
    frustum: undefined,
  };
  var scratch2DTo3DFrustumPersp = new PerspectiveFrustum();

  SceneTransitioner.prototype.morphTo3D = function (duration, ellipsoid) {
    if (defined(this._completeMorph)) {
      this._completeMorph();
    }

    var scene = this._scene;
    this._previousMode = scene.mode;

    if (
      this._previousMode === SceneMode$1.SCENE3D ||
      this._previousMode === SceneMode$1.MORPHING
    ) {
      return;
    }
    this._scene.morphStart.raiseEvent(
      this,
      this._previousMode,
      SceneMode$1.SCENE3D,
      true
    );

    scene._mode = SceneMode$1.MORPHING;
    scene.camera._setTransform(Matrix4.IDENTITY);

    if (this._previousMode === SceneMode$1.SCENE2D) {
      morphFrom2DTo3D(this, duration, ellipsoid);
    } else {
      var camera3D;
      if (duration > 0.0) {
        camera3D = scratchCVTo3DCamera;
        Cartesian3.fromDegrees(
          0.0,
          0.0,
          5.0 * ellipsoid.maximumRadius,
          ellipsoid,
          camera3D.position
        );
        Cartesian3.negate(camera3D.position, camera3D.direction);
        Cartesian3.normalize(camera3D.direction, camera3D.direction);
        Cartesian3.clone(Cartesian3.UNIT_Z, camera3D.up);
      } else {
        camera3D = getColumbusViewTo3DCamera(this, ellipsoid);
      }

      var frustum;
      var camera = scene.camera;
      if (camera.frustum instanceof OrthographicFrustum) {
        frustum = camera.frustum.clone();
      } else {
        frustum = scratch2DTo3DFrustumPersp;
        frustum.aspectRatio =
          scene.drawingBufferWidth / scene.drawingBufferHeight;
        frustum.fov = CesiumMath.toRadians(60.0);
      }
      camera3D.frustum = frustum;

      var complete = complete3DCallback(camera3D);
      createMorphHandler(this, complete);

      morphFromColumbusViewTo3D(this, duration, camera3D, complete);
    }

    if (duration === 0.0 && defined(this._completeMorph)) {
      this._completeMorph();
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   */
  SceneTransitioner.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * transitioner = transitioner && transitioner.destroy();
   */
  SceneTransitioner.prototype.destroy = function () {
    destroyMorphHandler(this);
    return destroyObject(this);
  };

  function createMorphHandler(transitioner, completeMorphFunction) {
    if (transitioner._scene.completeMorphOnUserInput) {
      transitioner._morphHandler = new ScreenSpaceEventHandler(
        transitioner._scene.canvas
      );

      var completeMorph = function () {
        transitioner._morphCancelled = true;
        transitioner._scene.camera.cancelFlight();
        completeMorphFunction(transitioner);
      };
      transitioner._completeMorph = completeMorph;
      transitioner._morphHandler.setInputAction(
        completeMorph,
        ScreenSpaceEventType$1.LEFT_DOWN
      );
      transitioner._morphHandler.setInputAction(
        completeMorph,
        ScreenSpaceEventType$1.MIDDLE_DOWN
      );
      transitioner._morphHandler.setInputAction(
        completeMorph,
        ScreenSpaceEventType$1.RIGHT_DOWN
      );
      transitioner._morphHandler.setInputAction(
        completeMorph,
        ScreenSpaceEventType$1.WHEEL
      );
    }
  }

  function destroyMorphHandler(transitioner) {
    var tweens = transitioner._currentTweens;
    for (var i = 0; i < tweens.length; ++i) {
      tweens[i].cancelTween();
    }
    transitioner._currentTweens.length = 0;
    transitioner._morphHandler =
      transitioner._morphHandler && transitioner._morphHandler.destroy();
  }

  var scratchCVTo3DCartographic = new Cartographic();
  var scratchCVTo3DSurfacePoint = new Cartesian3();
  var scratchCVTo3DFromENU = new Matrix4();

  function getColumbusViewTo3DCamera(transitioner, ellipsoid) {
    var scene = transitioner._scene;
    var camera = scene.camera;

    var camera3D = scratchCVTo3DCamera;
    var position = camera3D.position;
    var direction = camera3D.direction;
    var up = camera3D.up;

    var positionCarto = scene.mapProjection.unproject(
      camera.position,
      scratchCVTo3DCartographic
    );
    ellipsoid.cartographicToCartesian(positionCarto, position);
    var surfacePoint = ellipsoid.scaleToGeodeticSurface(
      position,
      scratchCVTo3DSurfacePoint
    );

    var fromENU = Transforms.eastNorthUpToFixedFrame(
      surfacePoint,
      ellipsoid,
      scratchCVTo3DFromENU
    );

    Matrix4.multiplyByPointAsVector(fromENU, camera.direction, direction);
    Matrix4.multiplyByPointAsVector(fromENU, camera.up, up);

    return camera3D;
  }

  var scratchCVTo3DStartPos = new Cartesian3();
  var scratchCVTo3DStartDir = new Cartesian3();
  var scratchCVTo3DStartUp = new Cartesian3();
  var scratchCVTo3DEndPos = new Cartesian3();
  var scratchCVTo3DEndDir = new Cartesian3();
  var scratchCVTo3DEndUp = new Cartesian3();

  function morphFromColumbusViewTo3D(
    transitioner,
    duration,
    endCamera,
    complete
  ) {
    duration *= 0.5;

    var scene = transitioner._scene;
    var camera = scene.camera;

    var startPos = Cartesian3.clone(camera.position, scratchCVTo3DStartPos);
    var startDir = Cartesian3.clone(camera.direction, scratchCVTo3DStartDir);
    var startUp = Cartesian3.clone(camera.up, scratchCVTo3DStartUp);

    var endPos = Matrix4.multiplyByPoint(
      Camera.TRANSFORM_2D_INVERSE,
      endCamera.position,
      scratchCVTo3DEndPos
    );
    var endDir = Matrix4.multiplyByPointAsVector(
      Camera.TRANSFORM_2D_INVERSE,
      endCamera.direction,
      scratchCVTo3DEndDir
    );
    var endUp = Matrix4.multiplyByPointAsVector(
      Camera.TRANSFORM_2D_INVERSE,
      endCamera.up,
      scratchCVTo3DEndUp
    );

    function update(value) {
      columbusViewMorph(startPos, endPos, value.time, camera.position);
      columbusViewMorph(startDir, endDir, value.time, camera.direction);
      columbusViewMorph(startUp, endUp, value.time, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
      Cartesian3.normalize(camera.right, camera.right);
    }

    var tween = scene.tweens.add({
      duration: duration,
      easingFunction: EasingFunction$1.QUARTIC_OUT,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: 1.0,
      },
      update: update,
      complete: function () {
        addMorphTimeAnimations(transitioner, scene, 0.0, 1.0, duration, complete);
      },
    });
    transitioner._currentTweens.push(tween);
  }

  var scratch2DTo3DFrustumOrtho = new OrthographicFrustum();
  var scratch3DToCVStartPos = new Cartesian3();
  var scratch3DToCVStartDir = new Cartesian3();
  var scratch3DToCVStartUp = new Cartesian3();
  var scratch3DToCVEndPos = new Cartesian3();
  var scratch3DToCVEndDir = new Cartesian3();
  var scratch3DToCVEndUp = new Cartesian3();

  function morphFrom2DTo3D(transitioner, duration, ellipsoid) {
    duration /= 3.0;

    var scene = transitioner._scene;
    var camera = scene.camera;

    var camera3D;
    if (duration > 0.0) {
      camera3D = scratchCVTo3DCamera;
      Cartesian3.fromDegrees(
        0.0,
        0.0,
        5.0 * ellipsoid.maximumRadius,
        ellipsoid,
        camera3D.position
      );
      Cartesian3.negate(camera3D.position, camera3D.direction);
      Cartesian3.normalize(camera3D.direction, camera3D.direction);
      Cartesian3.clone(Cartesian3.UNIT_Z, camera3D.up);
    } else {
      camera.position.z = camera.frustum.right - camera.frustum.left;

      camera3D = getColumbusViewTo3DCamera(transitioner, ellipsoid);
    }

    var frustum;
    if (transitioner._morphToOrthographic) {
      frustum = scratch2DTo3DFrustumOrtho;
      frustum.aspectRatio = scene.drawingBufferWidth / scene.drawingBufferHeight;
      frustum.width = camera.frustum.right - camera.frustum.left;
    } else {
      frustum = scratch2DTo3DFrustumPersp;
      frustum.aspectRatio = scene.drawingBufferWidth / scene.drawingBufferHeight;
      frustum.fov = CesiumMath.toRadians(60.0);
    }

    camera3D.frustum = frustum;

    var complete = complete3DCallback(camera3D);
    createMorphHandler(transitioner, complete);

    var morph;
    if (transitioner._morphToOrthographic) {
      morph = function () {
        morphFromColumbusViewTo3D(transitioner, duration, camera3D, complete);
      };
    } else {
      morph = function () {
        morphOrthographicToPerspective(
          transitioner,
          duration,
          camera3D,
          function () {
            morphFromColumbusViewTo3D(transitioner, duration, camera3D, complete);
          }
        );
      };
    }

    if (duration > 0.0) {
      scene._mode = SceneMode$1.SCENE2D;
      camera.flyTo({
        duration: duration,
        destination: Cartesian3.fromDegrees(
          0.0,
          0.0,
          5.0 * ellipsoid.maximumRadius,
          ellipsoid,
          scratch3DToCVEndPos
        ),
        complete: function () {
          scene._mode = SceneMode$1.MORPHING;
          morph();
        },
      });
    } else {
      morph();
    }
  }

  function columbusViewMorph(startPosition, endPosition, time, result) {
    // Just linear for now.
    return Cartesian3.lerp(startPosition, endPosition, time, result);
  }

  function morphPerspectiveToOrthographic(
    transitioner,
    duration,
    endCamera,
    updateHeight,
    complete
  ) {
    var scene = transitioner._scene;
    var camera = scene.camera;

    if (camera.frustum instanceof OrthographicFrustum) {
      return;
    }

    var startFOV = camera.frustum.fov;
    var endFOV = CesiumMath.RADIANS_PER_DEGREE * 0.5;
    var d = endCamera.position.z * Math.tan(startFOV * 0.5);
    camera.frustum.far = d / Math.tan(endFOV * 0.5) + 10000000.0;

    function update(value) {
      camera.frustum.fov = CesiumMath.lerp(startFOV, endFOV, value.time);
      var height = d / Math.tan(camera.frustum.fov * 0.5);
      updateHeight(camera, height);
    }
    var tween = scene.tweens.add({
      duration: duration,
      easingFunction: EasingFunction$1.QUARTIC_OUT,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: 1.0,
      },
      update: update,
      complete: function () {
        camera.frustum = endCamera.frustum.clone();
        complete(transitioner);
      },
    });
    transitioner._currentTweens.push(tween);
  }

  var scratchCVTo2DStartPos = new Cartesian3();
  var scratchCVTo2DStartDir = new Cartesian3();
  var scratchCVTo2DStartUp = new Cartesian3();
  var scratchCVTo2DEndPos = new Cartesian3();
  var scratchCVTo2DEndDir = new Cartesian3();
  var scratchCVTo2DEndUp = new Cartesian3();
  var scratchCVTo2DFrustum = new OrthographicOffCenterFrustum();
  var scratchCVTo2DRay = new Ray();
  var scratchCVTo2DPickPos = new Cartesian3();
  var scratchCVTo2DCamera = {
    position: undefined,
    direction: undefined,
    up: undefined,
    frustum: undefined,
  };

  function morphFromColumbusViewTo2D(transitioner, duration) {
    duration *= 0.5;

    var scene = transitioner._scene;
    var camera = scene.camera;

    var startPos = Cartesian3.clone(camera.position, scratchCVTo2DStartPos);
    var startDir = Cartesian3.clone(camera.direction, scratchCVTo2DStartDir);
    var startUp = Cartesian3.clone(camera.up, scratchCVTo2DStartUp);

    var endDir = Cartesian3.negate(Cartesian3.UNIT_Z, scratchCVTo2DEndDir);
    var endUp = Cartesian3.clone(Cartesian3.UNIT_Y, scratchCVTo2DEndUp);

    var endPos = scratchCVTo2DEndPos;

    if (duration > 0.0) {
      Cartesian3.clone(Cartesian3.ZERO, scratchCVTo2DEndPos);
      endPos.z = 5.0 * scene.mapProjection.ellipsoid.maximumRadius;
    } else {
      Cartesian3.clone(startPos, scratchCVTo2DEndPos);

      var ray = scratchCVTo2DRay;
      Matrix4.multiplyByPoint(Camera.TRANSFORM_2D, startPos, ray.origin);
      Matrix4.multiplyByPointAsVector(
        Camera.TRANSFORM_2D,
        startDir,
        ray.direction
      );

      var globe = scene.globe;
      if (defined(globe)) {
        var pickPos = globe.pickWorldCoordinates(
          ray,
          scene,
          true,
          scratchCVTo2DPickPos
        );
        if (defined(pickPos)) {
          Matrix4.multiplyByPoint(Camera.TRANSFORM_2D_INVERSE, pickPos, endPos);
          endPos.z += Cartesian3.distance(startPos, endPos);
        }
      }
    }

    var frustum = scratchCVTo2DFrustum;
    frustum.right = endPos.z * 0.5;
    frustum.left = -frustum.right;
    frustum.top =
      frustum.right * (scene.drawingBufferHeight / scene.drawingBufferWidth);
    frustum.bottom = -frustum.top;

    var camera2D = scratchCVTo2DCamera;
    camera2D.position = endPos;
    camera2D.direction = endDir;
    camera2D.up = endUp;
    camera2D.frustum = frustum;

    var complete = complete2DCallback(camera2D);
    createMorphHandler(transitioner, complete);

    function updateCV(value) {
      columbusViewMorph(startPos, endPos, value.time, camera.position);
      columbusViewMorph(startDir, endDir, value.time, camera.direction);
      columbusViewMorph(startUp, endUp, value.time, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
      Cartesian3.normalize(camera.right, camera.right);
      camera._adjustOrthographicFrustum(true);
    }

    function updateHeight(camera, height) {
      camera.position.z = height;
    }

    var tween = scene.tweens.add({
      duration: duration,
      easingFunction: EasingFunction$1.QUARTIC_OUT,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: 1.0,
      },
      update: updateCV,
      complete: function () {
        morphPerspectiveToOrthographic(
          transitioner,
          duration,
          camera2D,
          updateHeight,
          complete
        );
      },
    });
    transitioner._currentTweens.push(tween);
  }

  var scratch3DTo2DCartographic = new Cartographic();
  var scratch3DTo2DCamera = {
    position: new Cartesian3(),
    direction: new Cartesian3(),
    up: new Cartesian3(),
    position2D: new Cartesian3(),
    direction2D: new Cartesian3(),
    up2D: new Cartesian3(),
    frustum: new OrthographicOffCenterFrustum(),
  };
  var scratch3DTo2DEndCamera = {
    position: new Cartesian3(),
    direction: new Cartesian3(),
    up: new Cartesian3(),
    frustum: undefined,
  };
  var scratch3DTo2DPickPosition = new Cartesian3();
  var scratch3DTo2DRay = new Ray();
  var scratch3DTo2DToENU = new Matrix4();
  var scratch3DTo2DSurfacePoint = new Cartesian3();

  function morphFrom3DTo2D(transitioner, duration, ellipsoid) {
    duration *= 0.5;

    var scene = transitioner._scene;
    var camera = scene.camera;
    var camera2D = scratch3DTo2DCamera;

    if (duration > 0.0) {
      Cartesian3.clone(Cartesian3.ZERO, camera2D.position);
      camera2D.position.z = 5.0 * ellipsoid.maximumRadius;
      Cartesian3.negate(Cartesian3.UNIT_Z, camera2D.direction);
      Cartesian3.clone(Cartesian3.UNIT_Y, camera2D.up);
    } else {
      ellipsoid.cartesianToCartographic(
        camera.positionWC,
        scratch3DTo2DCartographic
      );
      scene.mapProjection.project(scratch3DTo2DCartographic, camera2D.position);

      Cartesian3.negate(Cartesian3.UNIT_Z, camera2D.direction);
      Cartesian3.clone(Cartesian3.UNIT_Y, camera2D.up);

      var ray = scratch3DTo2DRay;
      Cartesian3.clone(camera2D.position2D, ray.origin);
      var rayDirection = Cartesian3.clone(camera.directionWC, ray.direction);
      var surfacePoint = ellipsoid.scaleToGeodeticSurface(
        camera.positionWC,
        scratch3DTo2DSurfacePoint
      );
      var toENU = Transforms.eastNorthUpToFixedFrame(
        surfacePoint,
        ellipsoid,
        scratch3DTo2DToENU
      );
      Matrix4.inverseTransformation(toENU, toENU);
      Matrix4.multiplyByPointAsVector(toENU, rayDirection, rayDirection);
      Matrix4.multiplyByPointAsVector(
        Camera.TRANSFORM_2D,
        rayDirection,
        rayDirection
      );

      var globe = scene.globe;
      if (defined(globe)) {
        var pickedPos = globe.pickWorldCoordinates(
          ray,
          scene,
          true,
          scratch3DTo2DPickPosition
        );
        if (defined(pickedPos)) {
          var height = Cartesian3.distance(camera2D.position2D, pickedPos);
          pickedPos.x += height;
          Cartesian3.clone(pickedPos, camera2D.position2D);
        }
      }
    }

    function updateHeight(camera, height) {
      camera.position.x = height;
    }

    Matrix4.multiplyByPoint(
      Camera.TRANSFORM_2D,
      camera2D.position,
      camera2D.position2D
    );
    Matrix4.multiplyByPointAsVector(
      Camera.TRANSFORM_2D,
      camera2D.direction,
      camera2D.direction2D
    );
    Matrix4.multiplyByPointAsVector(
      Camera.TRANSFORM_2D,
      camera2D.up,
      camera2D.up2D
    );

    var frustum = camera2D.frustum;
    frustum.right = camera2D.position.z * 0.5;
    frustum.left = -frustum.right;
    frustum.top =
      frustum.right * (scene.drawingBufferHeight / scene.drawingBufferWidth);
    frustum.bottom = -frustum.top;

    var endCamera = scratch3DTo2DEndCamera;
    Matrix4.multiplyByPoint(
      Camera.TRANSFORM_2D_INVERSE,
      camera2D.position2D,
      endCamera.position
    );
    Cartesian3.clone(camera2D.direction, endCamera.direction);
    Cartesian3.clone(camera2D.up, endCamera.up);
    endCamera.frustum = frustum;

    var complete = complete2DCallback(endCamera);
    createMorphHandler(transitioner, complete);

    function completeCallback() {
      morphPerspectiveToOrthographic(
        transitioner,
        duration,
        camera2D,
        updateHeight,
        complete
      );
    }
    morphFrom3DToColumbusView(transitioner, duration, camera2D, completeCallback);
  }

  function morphOrthographicToPerspective(
    transitioner,
    duration,
    cameraCV,
    complete
  ) {
    var scene = transitioner._scene;
    var camera = scene.camera;

    var height = camera.frustum.right - camera.frustum.left;
    camera.frustum = cameraCV.frustum.clone();

    var endFOV = camera.frustum.fov;
    var startFOV = CesiumMath.RADIANS_PER_DEGREE * 0.5;
    var d = height * Math.tan(endFOV * 0.5);
    camera.frustum.far = d / Math.tan(startFOV * 0.5) + 10000000.0;
    camera.frustum.fov = startFOV;

    function update(value) {
      camera.frustum.fov = CesiumMath.lerp(startFOV, endFOV, value.time);
      camera.position.z = d / Math.tan(camera.frustum.fov * 0.5);
    }
    var tween = scene.tweens.add({
      duration: duration,
      easingFunction: EasingFunction$1.QUARTIC_OUT,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: 1.0,
      },
      update: update,
      complete: function () {
        complete(transitioner);
      },
    });
    transitioner._currentTweens.push(tween);
  }

  function morphFrom2DToColumbusView(transitioner, duration, cameraCV, complete) {
    duration *= 0.5;

    var scene = transitioner._scene;
    var camera = scene.camera;

    var endPos = Cartesian3.clone(cameraCV.position, scratch3DToCVEndPos);
    var endDir = Cartesian3.clone(cameraCV.direction, scratch3DToCVEndDir);
    var endUp = Cartesian3.clone(cameraCV.up, scratch3DToCVEndUp);

    scene._mode = SceneMode$1.MORPHING;

    function morph() {
      camera.frustum = cameraCV.frustum.clone();

      var startPos = Cartesian3.clone(camera.position, scratch3DToCVStartPos);
      var startDir = Cartesian3.clone(camera.direction, scratch3DToCVStartDir);
      var startUp = Cartesian3.clone(camera.up, scratch3DToCVStartUp);
      startPos.z = endPos.z;

      function update(value) {
        columbusViewMorph(startPos, endPos, value.time, camera.position);
        columbusViewMorph(startDir, endDir, value.time, camera.direction);
        columbusViewMorph(startUp, endUp, value.time, camera.up);
        Cartesian3.cross(camera.direction, camera.up, camera.right);
        Cartesian3.normalize(camera.right, camera.right);
      }
      var tween = scene.tweens.add({
        duration: duration,
        easingFunction: EasingFunction$1.QUARTIC_OUT,
        startObject: {
          time: 0.0,
        },
        stopObject: {
          time: 1.0,
        },
        update: update,
        complete: function () {
          complete(transitioner);
        },
      });
      transitioner._currentTweens.push(tween);
    }

    if (transitioner._morphToOrthographic) {
      morph();
    } else {
      morphOrthographicToPerspective(transitioner, 0.0, cameraCV, morph);
    }
  }

  function morphFrom3DToColumbusView(
    transitioner,
    duration,
    endCamera,
    complete
  ) {
    var scene = transitioner._scene;
    var camera = scene.camera;

    var startPos = Cartesian3.clone(camera.position, scratch3DToCVStartPos);
    var startDir = Cartesian3.clone(camera.direction, scratch3DToCVStartDir);
    var startUp = Cartesian3.clone(camera.up, scratch3DToCVStartUp);

    var endPos = Cartesian3.clone(endCamera.position2D, scratch3DToCVEndPos);
    var endDir = Cartesian3.clone(endCamera.direction2D, scratch3DToCVEndDir);
    var endUp = Cartesian3.clone(endCamera.up2D, scratch3DToCVEndUp);

    function update(value) {
      columbusViewMorph(startPos, endPos, value.time, camera.position);
      columbusViewMorph(startDir, endDir, value.time, camera.direction);
      columbusViewMorph(startUp, endUp, value.time, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
      Cartesian3.normalize(camera.right, camera.right);
      camera._adjustOrthographicFrustum(true);
    }
    var tween = scene.tweens.add({
      duration: duration,
      easingFunction: EasingFunction$1.QUARTIC_OUT,
      startObject: {
        time: 0.0,
      },
      stopObject: {
        time: 1.0,
      },
      update: update,
      complete: function () {
        addMorphTimeAnimations(transitioner, scene, 1.0, 0.0, duration, complete);
      },
    });
    transitioner._currentTweens.push(tween);
  }

  function addMorphTimeAnimations(
    transitioner,
    scene,
    start,
    stop,
    duration,
    complete
  ) {
    // Later, this will be linear and each object will adjust, if desired, in its vertex shader.
    var options = {
      object: scene,
      property: "morphTime",
      startValue: start,
      stopValue: stop,
      duration: duration,
      easingFunction: EasingFunction$1.QUARTIC_OUT,
    };

    if (defined(complete)) {
      options.complete = function () {
        complete(transitioner);
      };
    }

    var tween = scene.tweens.addProperty(options);
    transitioner._currentTweens.push(tween);
  }

  function complete3DCallback(camera3D) {
    return function (transitioner) {
      var scene = transitioner._scene;
      scene._mode = SceneMode$1.SCENE3D;
      scene.morphTime = SceneMode$1.getMorphTime(SceneMode$1.SCENE3D);

      destroyMorphHandler(transitioner);

      var camera = scene.camera;
      if (
        transitioner._previousMode !== SceneMode$1.MORPHING ||
        transitioner._morphCancelled
      ) {
        transitioner._morphCancelled = false;

        Cartesian3.clone(camera3D.position, camera.position);
        Cartesian3.clone(camera3D.direction, camera.direction);
        Cartesian3.clone(camera3D.up, camera.up);
        Cartesian3.cross(camera.direction, camera.up, camera.right);
        Cartesian3.normalize(camera.right, camera.right);

        camera.frustum = camera3D.frustum.clone();
      }

      var frustum = camera.frustum;
      if (scene.frameState.useLogDepth) {
        frustum.near = 0.1;
        frustum.far = 10000000000.0;
      }

      var wasMorphing = defined(transitioner._completeMorph);
      transitioner._completeMorph = undefined;
      scene.camera.update(scene.mode);
      transitioner._scene.morphComplete.raiseEvent(
        transitioner,
        transitioner._previousMode,
        SceneMode$1.SCENE3D,
        wasMorphing
      );
    };
  }

  function complete2DCallback(camera2D) {
    return function (transitioner) {
      var scene = transitioner._scene;

      scene._mode = SceneMode$1.SCENE2D;
      scene.morphTime = SceneMode$1.getMorphTime(SceneMode$1.SCENE2D);

      destroyMorphHandler(transitioner);

      var camera = scene.camera;
      Cartesian3.clone(camera2D.position, camera.position);
      camera.position.z = scene.mapProjection.ellipsoid.maximumRadius * 2.0;
      Cartesian3.clone(camera2D.direction, camera.direction);
      Cartesian3.clone(camera2D.up, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
      Cartesian3.normalize(camera.right, camera.right);
      camera.frustum = camera2D.frustum.clone();

      var wasMorphing = defined(transitioner._completeMorph);
      transitioner._completeMorph = undefined;
      scene.camera.update(scene.mode);
      transitioner._scene.morphComplete.raiseEvent(
        transitioner,
        transitioner._previousMode,
        SceneMode$1.SCENE2D,
        wasMorphing
      );
    };
  }

  function completeColumbusViewCallback(cameraCV) {
    return function (transitioner) {
      var scene = transitioner._scene;
      scene._mode = SceneMode$1.COLUMBUS_VIEW;
      scene.morphTime = SceneMode$1.getMorphTime(SceneMode$1.COLUMBUS_VIEW);

      destroyMorphHandler(transitioner);

      var camera = scene.camera;
      if (
        transitioner._previousModeMode !== SceneMode$1.MORPHING ||
        transitioner._morphCancelled
      ) {
        transitioner._morphCancelled = false;

        Cartesian3.clone(cameraCV.position, camera.position);
        Cartesian3.clone(cameraCV.direction, camera.direction);
        Cartesian3.clone(cameraCV.up, camera.up);
        Cartesian3.cross(camera.direction, camera.up, camera.right);
        Cartesian3.normalize(camera.right, camera.right);
      }

      var frustum = camera.frustum;
      if (scene.frameState.useLogDepth) {
        frustum.near = 0.1;
        frustum.far = 10000000000.0;
      }

      var wasMorphing = defined(transitioner._completeMorph);
      transitioner._completeMorph = undefined;
      scene.camera.update(scene.mode);
      transitioner._scene.morphComplete.raiseEvent(
        transitioner,
        transitioner._previousMode,
        SceneMode$1.COLUMBUS_VIEW,
        wasMorphing
      );
    };
  }

  /**
   * A tween is an animation that interpolates the properties of two objects using an {@link EasingFunction}.  Create
   * one using {@link Scene#tweens} and {@link TweenCollection#add} and related add functions.
   *
   * @alias Tween
   * @constructor
   *
   * @private
   */
  function Tween(
    tweens,
    tweenjs,
    startObject,
    stopObject,
    duration,
    delay,
    easingFunction,
    update,
    complete,
    cancel
  ) {
    this._tweens = tweens;
    this._tweenjs = tweenjs;

    this._startObject = clone(startObject);
    this._stopObject = clone(stopObject);

    this._duration = duration;
    this._delay = delay;
    this._easingFunction = easingFunction;

    this._update = update;
    this._complete = complete;

    /**
     * The callback to call if the tween is canceled either because {@link Tween#cancelTween}
     * was called or because the tween was removed from the collection.
     *
     * @type {TweenCollection.TweenCancelledCallback}
     */
    this.cancel = cancel;

    /**
     * @private
     */
    this.needsStart = true;
  }

  Object.defineProperties(Tween.prototype, {
    /**
     * An object with properties for initial values of the tween.  The properties of this object are changed during the tween's animation.
     * @memberof Tween.prototype
     *
     * @type {Object}
     * @readonly
     */
    startObject: {
      get: function () {
        return this._startObject;
      },
    },

    /**
     * An object with properties for the final values of the tween.
     * @memberof Tween.prototype
     *
     * @type {Object}
     * @readonly
     */
    stopObject: {
      get: function () {
        return this._stopObject;
      },
    },

    /**
     * The duration, in seconds, for the tween.  The tween is automatically removed from the collection when it stops.
     * @memberof Tween.prototype
     *
     * @type {Number}
     * @readonly
     */
    duration: {
      get: function () {
        return this._duration;
      },
    },

    /**
     * The delay, in seconds, before the tween starts animating.
     * @memberof Tween.prototype
     *
     * @type {Number}
     * @readonly
     */
    delay: {
      get: function () {
        return this._delay;
      },
    },

    /**
     * Determines the curve for animtion.
     * @memberof Tween.prototype
     *
     * @type {EasingFunction}
     * @readonly
     */
    easingFunction: {
      get: function () {
        return this._easingFunction;
      },
    },

    /**
     * The callback to call at each animation update (usually tied to the a rendered frame).
     * @memberof Tween.prototype
     *
     * @type {TweenCollection.TweenUpdateCallback}
     * @readonly
     */
    update: {
      get: function () {
        return this._update;
      },
    },

    /**
     * The callback to call when the tween finishes animating.
     * @memberof Tween.prototype
     *
     * @type {TweenCollection.TweenCompleteCallback}
     * @readonly
     */
    complete: {
      get: function () {
        return this._complete;
      },
    },

    /**
     * @memberof Tween.prototype
     *
     * @private
     */
    tweenjs: {
      get: function () {
        return this._tweenjs;
      },
    },
  });

  /**
   * Cancels the tween calling the {@link Tween#cancel} callback if one exists.  This
   * has no effect if the tween finished or was already canceled.
   */
  Tween.prototype.cancelTween = function () {
    this._tweens.remove(this);
  };

  /**
   * A collection of tweens for animating properties.  Commonly accessed using {@link Scene#tweens}.
   *
   * @alias TweenCollection
   * @constructor
   *
   * @private
   */
  function TweenCollection() {
    this._tweens = [];
  }

  Object.defineProperties(TweenCollection.prototype, {
    /**
     * The number of tweens in the collection.
     * @memberof TweenCollection.prototype
     *
     * @type {Number}
     * @readonly
     */
    length: {
      get: function () {
        return this._tweens.length;
      },
    },
  });

  /**
   * Creates a tween for animating between two sets of properties.  The tween starts animating at the next call to {@link TweenCollection#update}, which
   * is implicit when {@link Viewer} or {@link CesiumWidget} render the scene.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Object} options.startObject An object with properties for initial values of the tween.  The properties of this object are changed during the tween's animation.
   * @param {Object} options.stopObject An object with properties for the final values of the tween.
   * @param {Number} options.duration The duration, in seconds, for the tween.  The tween is automatically removed from the collection when it stops.
   * @param {Number} [options.delay=0.0] The delay, in seconds, before the tween starts animating.
   * @param {EasingFunction} [options.easingFunction=EasingFunction.LINEAR_NONE] Determines the curve for animtion.
   * @param {TweenCollection.TweenUpdateCallback} [options.update] The callback to call at each animation update (usually tied to the a rendered frame).
   * @param {TweenCollection.TweenCompleteCallback} [options.complete] The callback to call when the tween finishes animating.
   * @param {TweenCollection.TweenCancelledCallback} [options.cancel] The callback to call if the tween is canceled either because {@link Tween#cancelTween} was called or because the tween was removed from the collection.
   * @returns {Tween} The tween.
   *
   * @exception {DeveloperError} options.duration must be positive.
   */
  TweenCollection.prototype.add = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.startObject) || !defined(options.stopObject)) {
      throw new DeveloperError(
        "options.startObject and options.stopObject are required."
      );
    }

    if (!defined(options.duration) || options.duration < 0.0) {
      throw new DeveloperError(
        "options.duration is required and must be positive."
      );
    }
    //>>includeEnd('debug');

    if (options.duration === 0.0) {
      if (defined(options.complete)) {
        options.complete();
      }
      return new Tween(this);
    }

    var duration = options.duration / TimeConstants$1.SECONDS_PER_MILLISECOND;
    var delayInSeconds = defaultValue(options.delay, 0.0);
    var delay = delayInSeconds / TimeConstants$1.SECONDS_PER_MILLISECOND;
    var easingFunction = defaultValue(
      options.easingFunction,
      EasingFunction$1.LINEAR_NONE
    );

    var value = options.startObject;
    var tweenjs = new TWEEN.Tween(value);
    tweenjs.to(clone(options.stopObject), duration);
    tweenjs.delay(delay);
    tweenjs.easing(easingFunction);
    if (defined(options.update)) {
      tweenjs.onUpdate(function () {
        options.update(value);
      });
    }
    tweenjs.onComplete(defaultValue(options.complete, null));
    tweenjs.repeat(defaultValue(options._repeat, 0.0));

    var tween = new Tween(
      this,
      tweenjs,
      options.startObject,
      options.stopObject,
      options.duration,
      delayInSeconds,
      easingFunction,
      options.update,
      options.complete,
      options.cancel
    );
    this._tweens.push(tween);
    return tween;
  };

  /**
   * Creates a tween for animating a scalar property on the given object.  The tween starts animating at the next call to {@link TweenCollection#update}, which
   * is implicit when {@link Viewer} or {@link CesiumWidget} render the scene.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Object} options.object The object containing the property to animate.
   * @param {String} options.property The name of the property to animate.
   * @param {Number} options.startValue The initial value.
   * @param {Number} options.stopValue The final value.
   * @param {Number} [options.duration=3.0] The duration, in seconds, for the tween.  The tween is automatically removed from the collection when it stops.
   * @param {Number} [options.delay=0.0] The delay, in seconds, before the tween starts animating.
   * @param {EasingFunction} [options.easingFunction=EasingFunction.LINEAR_NONE] Determines the curve for animtion.
   * @param {TweenCollection.TweenUpdateCallback} [options.update] The callback to call at each animation update (usually tied to the a rendered frame).
   * @param {TweenCollection.TweenCompleteCallback} [options.complete] The callback to call when the tween finishes animating.
   * @param {TweenCollection.TweenCancelledCallback} [options.cancel] The callback to call if the tween is canceled either because {@link Tween#cancelTween} was called or because the tween was removed from the collection.
   * @returns {Tween} The tween.
   *
   * @exception {DeveloperError} options.object must have the specified property.
   * @exception {DeveloperError} options.duration must be positive.
   */
  TweenCollection.prototype.addProperty = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var object = options.object;
    var property = options.property;
    var startValue = options.startValue;
    var stopValue = options.stopValue;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(object) || !defined(options.property)) {
      throw new DeveloperError(
        "options.object and options.property are required."
      );
    }
    if (!defined(object[property])) {
      throw new DeveloperError(
        "options.object must have the specified property."
      );
    }
    if (!defined(startValue) || !defined(stopValue)) {
      throw new DeveloperError(
        "options.startValue and options.stopValue are required."
      );
    }
    //>>includeEnd('debug');

    function update(value) {
      object[property] = value.value;
    }

    return this.add({
      startObject: {
        value: startValue,
      },
      stopObject: {
        value: stopValue,
      },
      duration: defaultValue(options.duration, 3.0),
      delay: options.delay,
      easingFunction: options.easingFunction,
      update: update,
      complete: options.complete,
      cancel: options.cancel,
      _repeat: options._repeat,
    });
  };

  /**
   * Creates a tween for animating the alpha of all color uniforms on a {@link Material}.  The tween starts animating at the next call to {@link TweenCollection#update}, which
   * is implicit when {@link Viewer} or {@link CesiumWidget} render the scene.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Material} options.material The material to animate.
   * @param {Number} [options.startValue=0.0] The initial alpha value.
   * @param {Number} [options.stopValue=1.0] The final alpha value.
   * @param {Number} [options.duration=3.0] The duration, in seconds, for the tween.  The tween is automatically removed from the collection when it stops.
   * @param {Number} [options.delay=0.0] The delay, in seconds, before the tween starts animating.
   * @param {EasingFunction} [options.easingFunction=EasingFunction.LINEAR_NONE] Determines the curve for animtion.
   * @param {TweenCollection.TweenUpdateCallback} [options.update] The callback to call at each animation update (usually tied to the a rendered frame).
   * @param {TweenCollection.TweenCompleteCallback} [options.complete] The callback to call when the tween finishes animating.
   * @param {TweenCollection.TweenCancelledCallback} [options.cancel] The callback to call if the tween is canceled either because {@link Tween#cancelTween} was called or because the tween was removed from the collection.
   * @returns {Tween} The tween.
   *
   * @exception {DeveloperError} material has no properties with alpha components.
   * @exception {DeveloperError} options.duration must be positive.
   */
  TweenCollection.prototype.addAlpha = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var material = options.material;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(material)) {
      throw new DeveloperError("options.material is required.");
    }
    //>>includeEnd('debug');

    var properties = [];

    for (var property in material.uniforms) {
      if (
        material.uniforms.hasOwnProperty(property) &&
        defined(material.uniforms[property]) &&
        defined(material.uniforms[property].alpha)
      ) {
        properties.push(property);
      }
    }

    //>>includeStart('debug', pragmas.debug);
    if (properties.length === 0) {
      throw new DeveloperError(
        "material has no properties with alpha components."
      );
    }
    //>>includeEnd('debug');

    function update(value) {
      var length = properties.length;
      for (var i = 0; i < length; ++i) {
        material.uniforms[properties[i]].alpha = value.alpha;
      }
    }

    return this.add({
      startObject: {
        alpha: defaultValue(options.startValue, 0.0), // Default to fade in
      },
      stopObject: {
        alpha: defaultValue(options.stopValue, 1.0),
      },
      duration: defaultValue(options.duration, 3.0),
      delay: options.delay,
      easingFunction: options.easingFunction,
      update: update,
      complete: options.complete,
      cancel: options.cancel,
    });
  };

  /**
   * Creates a tween for animating the offset uniform of a {@link Material}.  The tween starts animating at the next call to {@link TweenCollection#update}, which
   * is implicit when {@link Viewer} or {@link CesiumWidget} render the scene.
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Material} options.material The material to animate.
   * @param {Number} options.startValue The initial alpha value.
   * @param {Number} options.stopValue The final alpha value.
   * @param {Number} [options.duration=3.0] The duration, in seconds, for the tween.  The tween is automatically removed from the collection when it stops.
   * @param {Number} [options.delay=0.0] The delay, in seconds, before the tween starts animating.
   * @param {EasingFunction} [options.easingFunction=EasingFunction.LINEAR_NONE] Determines the curve for animtion.
   * @param {TweenCollection.TweenUpdateCallback} [options.update] The callback to call at each animation update (usually tied to the a rendered frame).
   * @param {TweenCollection.TweenCancelledCallback} [options.cancel] The callback to call if the tween is canceled either because {@link Tween#cancelTween} was called or because the tween was removed from the collection.
   * @returns {Tween} The tween.
   *
   * @exception {DeveloperError} material.uniforms must have an offset property.
   * @exception {DeveloperError} options.duration must be positive.
   */
  TweenCollection.prototype.addOffsetIncrement = function (options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var material = options.material;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(material)) {
      throw new DeveloperError("material is required.");
    }
    if (!defined(material.uniforms.offset)) {
      throw new DeveloperError("material.uniforms must have an offset property.");
    }
    //>>includeEnd('debug');

    var uniforms = material.uniforms;
    return this.addProperty({
      object: uniforms,
      property: "offset",
      startValue: uniforms.offset,
      stopValue: uniforms.offset + 1,
      duration: options.duration,
      delay: options.delay,
      easingFunction: options.easingFunction,
      update: options.update,
      cancel: options.cancel,
      _repeat: Infinity,
    });
  };

  /**
   * Removes a tween from the collection.
   * <p>
   * This calls the {@link Tween#cancel} callback if the tween has one.
   * </p>
   *
   * @param {Tween} tween The tween to remove.
   * @returns {Boolean} <code>true</code> if the tween was removed; <code>false</code> if the tween was not found in the collection.
   */
  TweenCollection.prototype.remove = function (tween) {
    if (!defined(tween)) {
      return false;
    }

    var index = this._tweens.indexOf(tween);
    if (index !== -1) {
      tween.tweenjs.stop();
      if (defined(tween.cancel)) {
        tween.cancel();
      }
      this._tweens.splice(index, 1);
      return true;
    }

    return false;
  };

  /**
   * Removes all tweens from the collection.
   * <p>
   * This calls the {@link Tween#cancel} callback for each tween that has one.
   * </p>
   */
  TweenCollection.prototype.removeAll = function () {
    var tweens = this._tweens;

    for (var i = 0; i < tweens.length; ++i) {
      var tween = tweens[i];
      tween.tweenjs.stop();
      if (defined(tween.cancel)) {
        tween.cancel();
      }
    }
    tweens.length = 0;
  };

  /**
   * Determines whether this collection contains a given tween.
   *
   * @param {Tween} tween The tween to check for.
   * @returns {Boolean} <code>true</code> if this collection contains the tween, <code>false</code> otherwise.
   */
  TweenCollection.prototype.contains = function (tween) {
    return defined(tween) && this._tweens.indexOf(tween) !== -1;
  };

  /**
   * Returns the tween in the collection at the specified index.  Indices are zero-based
   * and increase as tweens are added.  Removing a tween shifts all tweens after
   * it to the left, changing their indices.  This function is commonly used to iterate over
   * all the tween in the collection.
   *
   * @param {Number} index The zero-based index of the tween.
   * @returns {Tween} The tween at the specified index.
   *
   * @example
   * // Output the duration of all the tweens in the collection.
   * var tweens = scene.tweens;
   * var length = tweens.length;
   * for (var i = 0; i < length; ++i) {
   *   console.log(tweens.get(i).duration);
   * }
   */
  TweenCollection.prototype.get = function (index) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(index)) {
      throw new DeveloperError("index is required.");
    }
    //>>includeEnd('debug');

    return this._tweens[index];
  };

  /**
   * Updates the tweens in the collection to be at the provide time.  When a tween finishes, it is removed
   * from the collection.
   *
   * @param {Number} [time=getTimestamp()] The time in seconds.  By default tweens are synced to the system clock.
   */
  TweenCollection.prototype.update = function (time) {
    var tweens = this._tweens;

    var i = 0;
    time = defined(time)
      ? time / TimeConstants$1.SECONDS_PER_MILLISECOND
      : getTimestamp$1();
    while (i < tweens.length) {
      var tween = tweens[i];
      var tweenjs = tween.tweenjs;

      if (tween.needsStart) {
        tween.needsStart = false;
        tweenjs.start(time);
      } else if (tweenjs.update(time)) {
        i++;
      } else {
        tweenjs.stop();
        tweens.splice(i, 1);
      }
    }
  };

  /**
   * Modifies the camera position and orientation based on mouse input to a canvas.
   * @alias ScreenSpaceCameraController
   * @constructor
   *
   * @param {Scene} scene The scene.
   */
  function ScreenSpaceCameraController(scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    /**
     * If true, inputs are allowed conditionally with the flags enableTranslate, enableZoom,
     * enableRotate, enableTilt, and enableLook.  If false, all inputs are disabled.
     *
     * NOTE: This setting is for temporary use cases, such as camera flights and
     * drag-selection of regions (see Picking demo).  It is typically set to false at the
     * start of such events, and set true on completion.  To keep inputs disabled
     * past the end of camera flights, you must use the other booleans (enableTranslate,
     * enableZoom, enableRotate, enableTilt, and enableLook).
     * @type {Boolean}
     * @default true
     */
    this.enableInputs = true;
    /**
     * If true, allows the user to pan around the map.  If false, the camera stays locked at the current position.
     * This flag only applies in 2D and Columbus view modes.
     * @type {Boolean}
     * @default true
     */
    this.enableTranslate = true;
    /**
     * If true, allows the user to zoom in and out.  If false, the camera is locked to the current distance from the ellipsoid.
     * @type {Boolean}
     * @default true
     */
    this.enableZoom = true;
    /**
     * If true, allows the user to rotate the world which translates the user's position.
     * This flag only applies in 2D and 3D.
     * @type {Boolean}
     * @default true
     */
    this.enableRotate = true;
    /**
     * If true, allows the user to tilt the camera.  If false, the camera is locked to the current heading.
     * This flag only applies in 3D and Columbus view.
     * @type {Boolean}
     * @default true
     */
    this.enableTilt = true;
    /**
     * If true, allows the user to use free-look. If false, the camera view direction can only be changed through translating
     * or rotating. This flag only applies in 3D and Columbus view modes.
     * @type {Boolean}
     * @default true
     */
    this.enableLook = true;
    /**
     * A parameter in the range <code>[0, 1)</code> used to determine how long
     * the camera will continue to spin because of inertia.
     * With value of zero, the camera will have no inertia.
     * @type {Number}
     * @default 0.9
     */
    this.inertiaSpin = 0.9;
    /**
     * A parameter in the range <code>[0, 1)</code> used to determine how long
     * the camera will continue to translate because of inertia.
     * With value of zero, the camera will have no inertia.
     * @type {Number}
     * @default 0.9
     */
    this.inertiaTranslate = 0.9;
    /**
     * A parameter in the range <code>[0, 1)</code> used to determine how long
     * the camera will continue to zoom because of inertia.
     * With value of zero, the camera will have no inertia.
     * @type {Number}
     * @default 0.8
     */
    this.inertiaZoom = 0.8;
    /**
     * A parameter in the range <code>[0, 1)</code> used to limit the range
     * of various user inputs to a percentage of the window width/height per animation frame.
     * This helps keep the camera under control in low-frame-rate situations.
     * @type {Number}
     * @default 0.1
     */
    this.maximumMovementRatio = 0.1;
    /**
     * Sets the duration, in seconds, of the bounce back animations in 2D and Columbus view.
     * @type {Number}
     * @default 3.0
     */
    this.bounceAnimationTime = 3.0;
    /**
     * The minimum magnitude, in meters, of the camera position when zooming. Defaults to 1.0.
     * @type {Number}
     * @default 1.0
     */
    this.minimumZoomDistance = 1.0;
    /**
     * The maximum magnitude, in meters, of the camera position when zooming. Defaults to positive infinity.
     * @type {Number}
     * @default {@link Number.POSITIVE_INFINITY}
     */
    this.maximumZoomDistance = Number.POSITIVE_INFINITY;
    /**
     * The input that allows the user to pan around the map. This only applies in 2D and Columbus view modes.
     * <p>
     * The type came be a {@link CameraEventType}, <code>undefined</code>, an object with <code>eventType</code>
     * and <code>modifier</code> properties with types <code>CameraEventType</code> and {@link KeyboardEventModifier},
     * or an array of any of the preceding.
     * </p>
     * @type {CameraEventType|Array|undefined}
     * @default {@link CameraEventType.LEFT_DRAG}
     */
    this.translateEventTypes = CameraEventType$1.LEFT_DRAG;
    /**
     * The input that allows the user to zoom in/out.
     * <p>
     * The type came be a {@link CameraEventType}, <code>undefined</code>, an object with <code>eventType</code>
     * and <code>modifier</code> properties with types <code>CameraEventType</code> and {@link KeyboardEventModifier},
     * or an array of any of the preceding.
     * </p>
     * @type {CameraEventType|Array|undefined}
     * @default [{@link CameraEventType.RIGHT_DRAG}, {@link CameraEventType.WHEEL}, {@link CameraEventType.PINCH}]
     */
    this.zoomEventTypes = [
      CameraEventType$1.RIGHT_DRAG,
      CameraEventType$1.WHEEL,
      CameraEventType$1.PINCH,
    ];
    /**
     * The input that allows the user to rotate around the globe or another object. This only applies in 3D and Columbus view modes.
     * <p>
     * The type came be a {@link CameraEventType}, <code>undefined</code>, an object with <code>eventType</code>
     * and <code>modifier</code> properties with types <code>CameraEventType</code> and {@link KeyboardEventModifier},
     * or an array of any of the preceding.
     * </p>
     * @type {CameraEventType|Array|undefined}
     * @default {@link CameraEventType.LEFT_DRAG}
     */
    this.rotateEventTypes = CameraEventType$1.LEFT_DRAG;
    /**
     * The input that allows the user to tilt in 3D and Columbus view or twist in 2D.
     * <p>
     * The type came be a {@link CameraEventType}, <code>undefined</code>, an object with <code>eventType</code>
     * and <code>modifier</code> properties with types <code>CameraEventType</code> and {@link KeyboardEventModifier},
     * or an array of any of the preceding.
     * </p>
     * @type {CameraEventType|Array|undefined}
     * @default [{@link CameraEventType.MIDDLE_DRAG}, {@link CameraEventType.PINCH}, {
     *     eventType : {@link CameraEventType.LEFT_DRAG},
     *     modifier : {@link KeyboardEventModifier.CTRL}
     * }, {
     *     eventType : {@link CameraEventType.RIGHT_DRAG},
     *     modifier : {@link KeyboardEventModifier.CTRL}
     * }]
     */
    this.tiltEventTypes = [
      CameraEventType$1.MIDDLE_DRAG,
      CameraEventType$1.PINCH,
      {
        eventType: CameraEventType$1.LEFT_DRAG,
        modifier: KeyboardEventModifier$1.CTRL,
      },
      {
        eventType: CameraEventType$1.RIGHT_DRAG,
        modifier: KeyboardEventModifier$1.CTRL,
      },
    ];
    /**
     * The input that allows the user to change the direction the camera is viewing. This only applies in 3D and Columbus view modes.
     * <p>
     * The type came be a {@link CameraEventType}, <code>undefined</code>, an object with <code>eventType</code>
     * and <code>modifier</code> properties with types <code>CameraEventType</code> and {@link KeyboardEventModifier},
     * or an array of any of the preceding.
     * </p>
     * @type {CameraEventType|Array|undefined}
     * @default { eventType : {@link CameraEventType.LEFT_DRAG}, modifier : {@link KeyboardEventModifier.SHIFT} }
     */
    this.lookEventTypes = {
      eventType: CameraEventType$1.LEFT_DRAG,
      modifier: KeyboardEventModifier$1.SHIFT,
    };
    /**
     * The minimum height the camera must be before picking the terrain instead of the ellipsoid.
     * @type {Number}
     * @default 150000.0
     */
    this.minimumPickingTerrainHeight = 150000.0;
    this._minimumPickingTerrainHeight = this.minimumPickingTerrainHeight;
    /**
     * The minimum height the camera must be before testing for collision with terrain.
     * @type {Number}
     * @default 15000.0
     */
    this.minimumCollisionTerrainHeight = 15000.0;
    this._minimumCollisionTerrainHeight = this.minimumCollisionTerrainHeight;
    /**
     * The minimum height the camera must be before switching from rotating a track ball to
     * free look when clicks originate on the sky or in space.
     * @type {Number}
     * @default 7500000.0
     */
    this.minimumTrackBallHeight = 7500000.0;
    this._minimumTrackBallHeight = this.minimumTrackBallHeight;
    /**
     * Enables or disables camera collision detection with terrain.
     * @type {Boolean}
     * @default true
     */
    this.enableCollisionDetection = true;

    this._scene = scene;
    this._globe = undefined;
    this._ellipsoid = undefined;

    this._aggregator = new CameraEventAggregator(scene.canvas);

    this._lastInertiaSpinMovement = undefined;
    this._lastInertiaZoomMovement = undefined;
    this._lastInertiaTranslateMovement = undefined;
    this._lastInertiaTiltMovement = undefined;

    // Zoom disables tilt, spin, and translate inertia
    // Tilt disables spin and translate inertia
    this._inertiaDisablers = {
      _lastInertiaZoomMovement: [
        "_lastInertiaSpinMovement",
        "_lastInertiaTranslateMovement",
        "_lastInertiaTiltMovement",
      ],
      _lastInertiaTiltMovement: [
        "_lastInertiaSpinMovement",
        "_lastInertiaTranslateMovement",
      ],
    };

    this._tweens = new TweenCollection();
    this._tween = undefined;

    this._horizontalRotationAxis = undefined;

    this._tiltCenterMousePosition = new Cartesian2(-1.0, -1.0);
    this._tiltCenter = new Cartesian3();
    this._rotateMousePosition = new Cartesian2(-1.0, -1.0);
    this._rotateStartPosition = new Cartesian3();
    this._strafeStartPosition = new Cartesian3();
    this._strafeMousePosition = new Cartesian2();
    this._strafeEndMousePosition = new Cartesian2();
    this._zoomMouseStart = new Cartesian2(-1.0, -1.0);
    this._zoomWorldPosition = new Cartesian3();
    this._useZoomWorldPosition = false;
    this._tiltCVOffMap = false;
    this._looking = false;
    this._rotating = false;
    this._strafing = false;
    this._zoomingOnVector = false;
    this._zoomingUnderground = false;
    this._rotatingZoom = false;
    this._adjustedHeightForTerrain = false;
    this._cameraUnderground = false;

    var projection = scene.mapProjection;
    this._maxCoord = projection.project(
      new Cartographic(Math.PI, CesiumMath.PI_OVER_TWO)
    );

    // Constants, Make any of these public?
    this._zoomFactor = 5.0;
    this._rotateFactor = undefined;
    this._rotateRateRangeAdjustment = undefined;
    this._maximumRotateRate = 1.77;
    this._minimumRotateRate = 1.0 / 5000.0;
    this._minimumZoomRate = 20.0;
    this._maximumZoomRate = 5906376272000.0; // distance from the Sun to Pluto in meters.
    this._minimumUndergroundPickDistance = 2000.0;
    this._maximumUndergroundPickDistance = 10000.0;
  }

  function decay(time, coefficient) {
    if (time < 0) {
      return 0.0;
    }

    var tau = (1.0 - coefficient) * 25.0;
    return Math.exp(-tau * time);
  }

  function sameMousePosition(movement) {
    return Cartesian2.equalsEpsilon(
      movement.startPosition,
      movement.endPosition,
      CesiumMath.EPSILON14
    );
  }

  // If the time between mouse down and mouse up is not between
  // these thresholds, the camera will not move with inertia.
  // This value is probably dependent on the browser and/or the
  // hardware. Should be investigated further.
  var inertiaMaxClickTimeThreshold = 0.4;

  function maintainInertia(
    aggregator,
    type,
    modifier,
    decayCoef,
    action,
    object,
    lastMovementName
  ) {
    var movementState = object[lastMovementName];
    if (!defined(movementState)) {
      movementState = object[lastMovementName] = {
        startPosition: new Cartesian2(),
        endPosition: new Cartesian2(),
        motion: new Cartesian2(),
        inertiaEnabled: true,
      };
    }

    var ts = aggregator.getButtonPressTime(type, modifier);
    var tr = aggregator.getButtonReleaseTime(type, modifier);

    var threshold = ts && tr && (tr.getTime() - ts.getTime()) / 1000.0;
    var now = new Date();
    var fromNow = tr && (now.getTime() - tr.getTime()) / 1000.0;

    if (ts && tr && threshold < inertiaMaxClickTimeThreshold) {
      var d = decay(fromNow, decayCoef);

      var lastMovement = aggregator.getLastMovement(type, modifier);
      if (
        !defined(lastMovement) ||
        sameMousePosition(lastMovement) ||
        !movementState.inertiaEnabled
      ) {
        return;
      }

      movementState.motion.x =
        (lastMovement.endPosition.x - lastMovement.startPosition.x) * 0.5;
      movementState.motion.y =
        (lastMovement.endPosition.y - lastMovement.startPosition.y) * 0.5;

      movementState.startPosition = Cartesian2.clone(
        lastMovement.startPosition,
        movementState.startPosition
      );

      movementState.endPosition = Cartesian2.multiplyByScalar(
        movementState.motion,
        d,
        movementState.endPosition
      );
      movementState.endPosition = Cartesian2.add(
        movementState.startPosition,
        movementState.endPosition,
        movementState.endPosition
      );

      // If value from the decreasing exponential function is close to zero,
      // the end coordinates may be NaN.
      if (
        isNaN(movementState.endPosition.x) ||
        isNaN(movementState.endPosition.y) ||
        Cartesian2.distance(
          movementState.startPosition,
          movementState.endPosition
        ) < 0.5
      ) {
        return;
      }

      if (!aggregator.isButtonDown(type, modifier)) {
        var startPosition = aggregator.getStartMousePosition(type, modifier);
        action(object, startPosition, movementState);
      }
    }
  }

  function activateInertia(controller, inertiaStateName) {
    if (defined(inertiaStateName)) {
      // Re-enable inertia if it was disabled
      var movementState = controller[inertiaStateName];
      if (defined(movementState)) {
        movementState.inertiaEnabled = true;
      }
      // Disable inertia on other movements
      var inertiasToDisable = controller._inertiaDisablers[inertiaStateName];
      if (defined(inertiasToDisable)) {
        var length = inertiasToDisable.length;
        for (var i = 0; i < length; ++i) {
          movementState = controller[inertiasToDisable[i]];
          if (defined(movementState)) {
            movementState.inertiaEnabled = false;
          }
        }
      }
    }
  }

  var scratchEventTypeArray = [];

  function reactToInput(
    controller,
    enabled,
    eventTypes,
    action,
    inertiaConstant,
    inertiaStateName
  ) {
    if (!defined(eventTypes)) {
      return;
    }

    var aggregator = controller._aggregator;

    if (!Array.isArray(eventTypes)) {
      scratchEventTypeArray[0] = eventTypes;
      eventTypes = scratchEventTypeArray;
    }

    var length = eventTypes.length;
    for (var i = 0; i < length; ++i) {
      var eventType = eventTypes[i];
      var type = defined(eventType.eventType) ? eventType.eventType : eventType;
      var modifier = eventType.modifier;

      var movement =
        aggregator.isMoving(type, modifier) &&
        aggregator.getMovement(type, modifier);
      var startPosition = aggregator.getStartMousePosition(type, modifier);

      if (controller.enableInputs && enabled) {
        if (movement) {
          action(controller, startPosition, movement);
          activateInertia(controller, inertiaStateName);
        } else if (inertiaConstant < 1.0) {
          maintainInertia(
            aggregator,
            type,
            modifier,
            inertiaConstant,
            action,
            controller,
            inertiaStateName
          );
        }
      }
    }
  }

  var scratchZoomPickRay = new Ray();
  var scratchPickCartesian = new Cartesian3();
  var scratchZoomOffset = new Cartesian2();
  var scratchZoomDirection = new Cartesian3();
  var scratchCenterPixel = new Cartesian2();
  var scratchCenterPosition = new Cartesian3();
  var scratchPositionNormal$2 = new Cartesian3();
  var scratchPickNormal = new Cartesian3();
  var scratchZoomAxis = new Cartesian3();
  var scratchCameraPositionNormal = new Cartesian3();

  // Scratch variables used in zooming algorithm
  var scratchTargetNormal = new Cartesian3();
  var scratchCameraPosition$1 = new Cartesian3();
  var scratchCameraUpNormal = new Cartesian3();
  var scratchCameraRightNormal = new Cartesian3();
  var scratchForwardNormal = new Cartesian3();
  var scratchPositionToTarget = new Cartesian3();
  var scratchPositionToTargetNormal = new Cartesian3();
  var scratchPan = new Cartesian3();
  var scratchCenterMovement = new Cartesian3();
  var scratchCenter$6 = new Cartesian3();
  var scratchCartesian$9 = new Cartesian3();
  var scratchCartesianTwo = new Cartesian3();
  var scratchCartesianThree = new Cartesian3();
  var scratchZoomViewOptions = {
    orientation: new HeadingPitchRoll(),
  };

  function handleZoom(
    object,
    startPosition,
    movement,
    zoomFactor,
    distanceMeasure,
    unitPositionDotDirection
  ) {
    var percentage = 1.0;
    if (defined(unitPositionDotDirection)) {
      percentage = CesiumMath.clamp(
        Math.abs(unitPositionDotDirection),
        0.25,
        1.0
      );
    }

    // distanceMeasure should be the height above the ellipsoid.
    // The zoomRate slows as it approaches the surface and stops minimumZoomDistance above it.
    var minHeight = object.minimumZoomDistance * percentage;
    var maxHeight = object.maximumZoomDistance;

    var minDistance = distanceMeasure - minHeight;
    var zoomRate = zoomFactor * minDistance;
    zoomRate = CesiumMath.clamp(
      zoomRate,
      object._minimumZoomRate,
      object._maximumZoomRate
    );

    var diff = movement.endPosition.y - movement.startPosition.y;
    var rangeWindowRatio = diff / object._scene.canvas.clientHeight;
    rangeWindowRatio = Math.min(rangeWindowRatio, object.maximumMovementRatio);
    var distance = zoomRate * rangeWindowRatio;

    if (
      object.enableCollisionDetection ||
      object.minimumZoomDistance === 0.0 ||
      !defined(object._globe) // look-at mode
    ) {
      if (distance > 0.0 && Math.abs(distanceMeasure - minHeight) < 1.0) {
        return;
      }

      if (distance < 0.0 && Math.abs(distanceMeasure - maxHeight) < 1.0) {
        return;
      }

      if (distanceMeasure - distance < minHeight) {
        distance = distanceMeasure - minHeight - 1.0;
      } else if (distanceMeasure - distance > maxHeight) {
        distance = distanceMeasure - maxHeight;
      }
    }

    var scene = object._scene;
    var camera = scene.camera;
    var mode = scene.mode;

    var orientation = scratchZoomViewOptions.orientation;
    orientation.heading = camera.heading;
    orientation.pitch = camera.pitch;
    orientation.roll = camera.roll;

    if (camera.frustum instanceof OrthographicFrustum) {
      if (Math.abs(distance) > 0.0) {
        camera.zoomIn(distance);
        camera._adjustOrthographicFrustum();
      }
      return;
    }

    var sameStartPosition = Cartesian2.equals(
      startPosition,
      object._zoomMouseStart
    );
    var zoomingOnVector = object._zoomingOnVector;
    var rotatingZoom = object._rotatingZoom;
    var pickedPosition;

    if (!sameStartPosition) {
      object._zoomMouseStart = Cartesian2.clone(
        startPosition,
        object._zoomMouseStart
      );

      if (defined(object._globe)) {
        if (mode === SceneMode$1.SCENE2D) {
          pickedPosition = camera.getPickRay(startPosition, scratchZoomPickRay)
            .origin;
          pickedPosition = Cartesian3.fromElements(
            pickedPosition.y,
            pickedPosition.z,
            pickedPosition.x
          );
        } else {
          pickedPosition = pickGlobe(object, startPosition, scratchPickCartesian);
        }
      }
      if (defined(pickedPosition)) {
        object._useZoomWorldPosition = true;
        object._zoomWorldPosition = Cartesian3.clone(
          pickedPosition,
          object._zoomWorldPosition
        );
      } else {
        object._useZoomWorldPosition = false;
      }

      zoomingOnVector = object._zoomingOnVector = false;
      rotatingZoom = object._rotatingZoom = false;
      object._zoomingUnderground = object._cameraUnderground;
    }

    if (!object._useZoomWorldPosition) {
      camera.zoomIn(distance);
      return;
    }

    var zoomOnVector = mode === SceneMode$1.COLUMBUS_VIEW;

    if (camera.positionCartographic.height < 2000000) {
      rotatingZoom = true;
    }

    if (!sameStartPosition || rotatingZoom) {
      if (mode === SceneMode$1.SCENE2D) {
        var worldPosition = object._zoomWorldPosition;
        var endPosition = camera.position;

        if (
          !Cartesian3.equals(worldPosition, endPosition) &&
          camera.positionCartographic.height < object._maxCoord.x * 2.0
        ) {
          var savedX = camera.position.x;

          var direction = Cartesian3.subtract(
            worldPosition,
            endPosition,
            scratchZoomDirection
          );
          Cartesian3.normalize(direction, direction);

          var d =
            (Cartesian3.distance(worldPosition, endPosition) * distance) /
            (camera.getMagnitude() * 0.5);
          camera.move(direction, d * 0.5);

          if (
            (camera.position.x < 0.0 && savedX > 0.0) ||
            (camera.position.x > 0.0 && savedX < 0.0)
          ) {
            pickedPosition = camera.getPickRay(startPosition, scratchZoomPickRay)
              .origin;
            pickedPosition = Cartesian3.fromElements(
              pickedPosition.y,
              pickedPosition.z,
              pickedPosition.x
            );
            object._zoomWorldPosition = Cartesian3.clone(
              pickedPosition,
              object._zoomWorldPosition
            );
          }
        }
      } else if (mode === SceneMode$1.SCENE3D) {
        var cameraPositionNormal = Cartesian3.normalize(
          camera.position,
          scratchCameraPositionNormal
        );
        if (
          object._cameraUnderground ||
          object._zoomingUnderground ||
          (camera.positionCartographic.height < 3000.0 &&
            Math.abs(Cartesian3.dot(camera.direction, cameraPositionNormal)) <
              0.6)
        ) {
          zoomOnVector = true;
        } else {
          var canvas = scene.canvas;

          var centerPixel = scratchCenterPixel;
          centerPixel.x = canvas.clientWidth / 2;
          centerPixel.y = canvas.clientHeight / 2;
          var centerPosition = pickGlobe(
            object,
            centerPixel,
            scratchCenterPosition
          );
          // If centerPosition is not defined, it means the globe does not cover the center position of screen

          if (
            defined(centerPosition) &&
            camera.positionCartographic.height < 1000000
          ) {
            var cameraPosition = scratchCameraPosition$1;
            Cartesian3.clone(camera.position, cameraPosition);
            var target = object._zoomWorldPosition;

            var targetNormal = scratchTargetNormal;

            targetNormal = Cartesian3.normalize(target, targetNormal);

            if (Cartesian3.dot(targetNormal, cameraPositionNormal) < 0.0) {
              return;
            }

            var center = scratchCenter$6;
            var forward = scratchForwardNormal;
            Cartesian3.clone(camera.direction, forward);
            Cartesian3.add(
              cameraPosition,
              Cartesian3.multiplyByScalar(forward, 1000, scratchCartesian$9),
              center
            );

            var positionToTarget = scratchPositionToTarget;
            var positionToTargetNormal = scratchPositionToTargetNormal;
            Cartesian3.subtract(target, cameraPosition, positionToTarget);

            Cartesian3.normalize(positionToTarget, positionToTargetNormal);

            var alphaDot = Cartesian3.dot(
              cameraPositionNormal,
              positionToTargetNormal
            );
            if (alphaDot >= 0.0) {
              // We zoomed past the target, and this zoom is not valid anymore.
              // This line causes the next zoom movement to pick a new starting point.
              object._zoomMouseStart.x = -1;
              return;
            }
            var alpha = Math.acos(-alphaDot);
            var cameraDistance = Cartesian3.magnitude(cameraPosition);
            var targetDistance = Cartesian3.magnitude(target);
            var remainingDistance = cameraDistance - distance;
            var positionToTargetDistance = Cartesian3.magnitude(positionToTarget);

            var gamma = Math.asin(
              CesiumMath.clamp(
                (positionToTargetDistance / targetDistance) * Math.sin(alpha),
                -1.0,
                1.0
              )
            );
            var delta = Math.asin(
              CesiumMath.clamp(
                (remainingDistance / targetDistance) * Math.sin(alpha),
                -1.0,
                1.0
              )
            );
            var beta = gamma - delta + alpha;

            var up = scratchCameraUpNormal;
            Cartesian3.normalize(cameraPosition, up);
            var right = scratchCameraRightNormal;
            right = Cartesian3.cross(positionToTargetNormal, up, right);
            right = Cartesian3.normalize(right, right);

            Cartesian3.normalize(
              Cartesian3.cross(up, right, scratchCartesian$9),
              forward
            );

            // Calculate new position to move to
            Cartesian3.multiplyByScalar(
              Cartesian3.normalize(center, scratchCartesian$9),
              Cartesian3.magnitude(center) - distance,
              center
            );
            Cartesian3.normalize(cameraPosition, cameraPosition);
            Cartesian3.multiplyByScalar(
              cameraPosition,
              remainingDistance,
              cameraPosition
            );

            // Pan
            var pMid = scratchPan;
            Cartesian3.multiplyByScalar(
              Cartesian3.add(
                Cartesian3.multiplyByScalar(
                  up,
                  Math.cos(beta) - 1,
                  scratchCartesianTwo
                ),
                Cartesian3.multiplyByScalar(
                  forward,
                  Math.sin(beta),
                  scratchCartesianThree
                ),
                scratchCartesian$9
              ),
              remainingDistance,
              pMid
            );
            Cartesian3.add(cameraPosition, pMid, cameraPosition);

            Cartesian3.normalize(center, up);
            Cartesian3.normalize(
              Cartesian3.cross(up, right, scratchCartesian$9),
              forward
            );

            var cMid = scratchCenterMovement;
            Cartesian3.multiplyByScalar(
              Cartesian3.add(
                Cartesian3.multiplyByScalar(
                  up,
                  Math.cos(beta) - 1,
                  scratchCartesianTwo
                ),
                Cartesian3.multiplyByScalar(
                  forward,
                  Math.sin(beta),
                  scratchCartesianThree
                ),
                scratchCartesian$9
              ),
              Cartesian3.magnitude(center),
              cMid
            );
            Cartesian3.add(center, cMid, center);

            // Update camera

            // Set new position
            Cartesian3.clone(cameraPosition, camera.position);

            // Set new direction
            Cartesian3.normalize(
              Cartesian3.subtract(center, cameraPosition, scratchCartesian$9),
              camera.direction
            );
            Cartesian3.clone(camera.direction, camera.direction);

            // Set new right & up vectors
            Cartesian3.cross(camera.direction, camera.up, camera.right);
            Cartesian3.cross(camera.right, camera.direction, camera.up);

            camera.setView(scratchZoomViewOptions);
            return;
          }

          if (defined(centerPosition)) {
            var positionNormal = Cartesian3.normalize(
              centerPosition,
              scratchPositionNormal$2
            );
            var pickedNormal = Cartesian3.normalize(
              object._zoomWorldPosition,
              scratchPickNormal
            );
            var dotProduct = Cartesian3.dot(pickedNormal, positionNormal);

            if (dotProduct > 0.0 && dotProduct < 1.0) {
              var angle = CesiumMath.acosClamped(dotProduct);
              var axis = Cartesian3.cross(
                pickedNormal,
                positionNormal,
                scratchZoomAxis
              );

              var denom =
                Math.abs(angle) > CesiumMath.toRadians(20.0)
                  ? camera.positionCartographic.height * 0.75
                  : camera.positionCartographic.height - distance;
              var scalar = distance / denom;
              camera.rotate(axis, angle * scalar);
            }
          } else {
            zoomOnVector = true;
          }
        }
      }

      object._rotatingZoom = !zoomOnVector;
    }

    if ((!sameStartPosition && zoomOnVector) || zoomingOnVector) {
      var ray;
      var zoomMouseStart = SceneTransforms.wgs84ToWindowCoordinates(
        scene,
        object._zoomWorldPosition,
        scratchZoomOffset
      );
      if (
        mode !== SceneMode$1.COLUMBUS_VIEW &&
        Cartesian2.equals(startPosition, object._zoomMouseStart) &&
        defined(zoomMouseStart)
      ) {
        ray = camera.getPickRay(zoomMouseStart, scratchZoomPickRay);
      } else {
        ray = camera.getPickRay(startPosition, scratchZoomPickRay);
      }

      var rayDirection = ray.direction;
      if (mode === SceneMode$1.COLUMBUS_VIEW || mode === SceneMode$1.SCENE2D) {
        Cartesian3.fromElements(
          rayDirection.y,
          rayDirection.z,
          rayDirection.x,
          rayDirection
        );
      }

      camera.move(rayDirection, distance);

      object._zoomingOnVector = true;
    } else {
      camera.zoomIn(distance);
    }

    if (!object._cameraUnderground) {
      camera.setView(scratchZoomViewOptions);
    }
  }

  var translate2DStart = new Ray();
  var translate2DEnd = new Ray();
  var scratchTranslateP0 = new Cartesian3();

  function translate2D(controller, startPosition, movement) {
    var scene = controller._scene;
    var camera = scene.camera;
    var start = camera.getPickRay(movement.startPosition, translate2DStart)
      .origin;
    var end = camera.getPickRay(movement.endPosition, translate2DEnd).origin;

    start = Cartesian3.fromElements(start.y, start.z, start.x, start);
    end = Cartesian3.fromElements(end.y, end.z, end.x, end);

    var direction = Cartesian3.subtract(start, end, scratchTranslateP0);
    var distance = Cartesian3.magnitude(direction);

    if (distance > 0.0) {
      Cartesian3.normalize(direction, direction);
      camera.move(direction, distance);
    }
  }

  function zoom2D$1(controller, startPosition, movement) {
    if (defined(movement.distance)) {
      movement = movement.distance;
    }

    var scene = controller._scene;
    var camera = scene.camera;

    handleZoom(
      controller,
      startPosition,
      movement,
      controller._zoomFactor,
      camera.getMagnitude()
    );
  }

  var twist2DStart = new Cartesian2();
  var twist2DEnd = new Cartesian2();

  function twist2D(controller, startPosition, movement) {
    if (defined(movement.angleAndHeight)) {
      singleAxisTwist2D(controller, startPosition, movement.angleAndHeight);
      return;
    }

    var scene = controller._scene;
    var camera = scene.camera;
    var canvas = scene.canvas;
    var width = canvas.clientWidth;
    var height = canvas.clientHeight;

    var start = twist2DStart;
    start.x = (2.0 / width) * movement.startPosition.x - 1.0;
    start.y = (2.0 / height) * (height - movement.startPosition.y) - 1.0;
    start = Cartesian2.normalize(start, start);

    var end = twist2DEnd;
    end.x = (2.0 / width) * movement.endPosition.x - 1.0;
    end.y = (2.0 / height) * (height - movement.endPosition.y) - 1.0;
    end = Cartesian2.normalize(end, end);

    var startTheta = CesiumMath.acosClamped(start.x);
    if (start.y < 0) {
      startTheta = CesiumMath.TWO_PI - startTheta;
    }
    var endTheta = CesiumMath.acosClamped(end.x);
    if (end.y < 0) {
      endTheta = CesiumMath.TWO_PI - endTheta;
    }
    var theta = endTheta - startTheta;

    camera.twistRight(theta);
  }

  function singleAxisTwist2D(controller, startPosition, movement) {
    var rotateRate =
      controller._rotateFactor * controller._rotateRateRangeAdjustment;

    if (rotateRate > controller._maximumRotateRate) {
      rotateRate = controller._maximumRotateRate;
    }

    if (rotateRate < controller._minimumRotateRate) {
      rotateRate = controller._minimumRotateRate;
    }

    var scene = controller._scene;
    var camera = scene.camera;
    var canvas = scene.canvas;

    var phiWindowRatio =
      (movement.endPosition.x - movement.startPosition.x) / canvas.clientWidth;
    phiWindowRatio = Math.min(phiWindowRatio, controller.maximumMovementRatio);

    var deltaPhi = rotateRate * phiWindowRatio * Math.PI * 4.0;

    camera.twistRight(deltaPhi);
  }

  function update2D(controller) {
    var rotatable2D = controller._scene.mapMode2D === MapMode2D$1.ROTATE;
    if (!Matrix4.equals(Matrix4.IDENTITY, controller._scene.camera.transform)) {
      reactToInput(
        controller,
        controller.enableZoom,
        controller.zoomEventTypes,
        zoom2D$1,
        controller.inertiaZoom,
        "_lastInertiaZoomMovement"
      );
      if (rotatable2D) {
        reactToInput(
          controller,
          controller.enableRotate,
          controller.translateEventTypes,
          twist2D,
          controller.inertiaSpin,
          "_lastInertiaSpinMovement"
        );
      }
    } else {
      reactToInput(
        controller,
        controller.enableTranslate,
        controller.translateEventTypes,
        translate2D,
        controller.inertiaTranslate,
        "_lastInertiaTranslateMovement"
      );
      reactToInput(
        controller,
        controller.enableZoom,
        controller.zoomEventTypes,
        zoom2D$1,
        controller.inertiaZoom,
        "_lastInertiaZoomMovement"
      );
      if (rotatable2D) {
        reactToInput(
          controller,
          controller.enableRotate,
          controller.tiltEventTypes,
          twist2D,
          controller.inertiaSpin,
          "_lastInertiaTiltMovement"
        );
      }
    }
  }

  var pickGlobeScratchRay = new Ray();
  var scratchDepthIntersection$1 = new Cartesian3();
  var scratchRayIntersection$1 = new Cartesian3();

  function pickGlobe(controller, mousePosition, result) {
    var scene = controller._scene;
    var globe = controller._globe;
    var camera = scene.camera;

    if (!defined(globe)) {
      return undefined;
    }

    var cullBackFaces = !controller._cameraUnderground;

    var depthIntersection;
    if (scene.pickPositionSupported) {
      depthIntersection = scene.pickPositionWorldCoordinates(
        mousePosition,
        scratchDepthIntersection$1
      );
    }

    var ray = camera.getPickRay(mousePosition, pickGlobeScratchRay);
    var rayIntersection = globe.pickWorldCoordinates(
      ray,
      scene,
      cullBackFaces,
      scratchRayIntersection$1
    );

    var pickDistance = defined(depthIntersection)
      ? Cartesian3.distance(depthIntersection, camera.positionWC)
      : Number.POSITIVE_INFINITY;
    var rayDistance = defined(rayIntersection)
      ? Cartesian3.distance(rayIntersection, camera.positionWC)
      : Number.POSITIVE_INFINITY;

    if (pickDistance < rayDistance) {
      return Cartesian3.clone(depthIntersection, result);
    }

    return Cartesian3.clone(rayIntersection, result);
  }

  var scratchDistanceCartographic = new Cartographic();

  function getDistanceFromSurface(controller) {
    var ellipsoid = controller._ellipsoid;
    var scene = controller._scene;
    var camera = scene.camera;
    var mode = scene.mode;

    var height = 0.0;
    if (mode === SceneMode$1.SCENE3D) {
      var cartographic = ellipsoid.cartesianToCartographic(
        camera.position,
        scratchDistanceCartographic
      );
      if (defined(cartographic)) {
        height = cartographic.height;
      }
    } else {
      height = camera.position.z;
    }
    var globeHeight = defaultValue(controller._scene.globeHeight, 0.0);
    var distanceFromSurface = Math.abs(globeHeight - height);
    return distanceFromSurface;
  }

  var scratchSurfaceNormal$1 = new Cartesian3();

  function getZoomDistanceUnderground(controller, ray) {
    var origin = ray.origin;
    var direction = ray.direction;
    var distanceFromSurface = getDistanceFromSurface(controller);

    // Weight zoom distance based on how strongly the pick ray is pointing inward.
    // Geocentric normal is accurate enough for these purposes
    var surfaceNormal = Cartesian3.normalize(origin, scratchSurfaceNormal$1);
    var strength = Math.abs(Cartesian3.dot(surfaceNormal, direction));
    strength = Math.max(strength, 0.5) * 2.0;
    return distanceFromSurface * strength;
  }

  function getTiltCenterUnderground(controller, ray, pickedPosition, result) {
    var distance = Cartesian3.distance(ray.origin, pickedPosition);
    var distanceFromSurface = getDistanceFromSurface(controller);

    var maximumDistance = CesiumMath.clamp(
      distanceFromSurface * 5.0,
      controller._minimumUndergroundPickDistance,
      controller._maximumUndergroundPickDistance
    );

    if (distance > maximumDistance) {
      // Simulate look-at behavior by tilting around a small invisible sphere
      distance = Math.min(distance, distanceFromSurface / 5.0);
      distance = Math.max(distance, 100.0);
    }

    return Ray.getPoint(ray, distance, result);
  }

  function getStrafeStartPositionUnderground(
    controller,
    ray,
    pickedPosition,
    result
  ) {
    var distance;
    if (!defined(pickedPosition)) {
      distance = getDistanceFromSurface(controller);
    } else {
      distance = Cartesian3.distance(ray.origin, pickedPosition);
      if (distance > controller._maximumUndergroundPickDistance) {
        // If the picked position is too far away set the strafe speed based on the
        // camera's height from the globe surface
        distance = getDistanceFromSurface(controller);
      }
    }

    return Ray.getPoint(ray, distance, result);
  }

  var scratchInertialDelta = new Cartesian2();

  function continueStrafing(controller, movement) {
    // Update the end position continually based on the inertial delta
    var originalEndPosition = movement.endPosition;
    var inertialDelta = Cartesian2.subtract(
      movement.endPosition,
      movement.startPosition,
      scratchInertialDelta
    );
    var endPosition = controller._strafeEndMousePosition;
    Cartesian2.add(endPosition, inertialDelta, endPosition);
    movement.endPosition = endPosition;
    strafe(controller, movement, controller._strafeStartPosition);
    movement.endPosition = originalEndPosition;
  }

  var translateCVStartRay = new Ray();
  var translateCVEndRay = new Ray();
  var translateCVStartPos = new Cartesian3();
  var translateCVEndPos = new Cartesian3();
  var translateCVDifference = new Cartesian3();
  var translateCVOrigin = new Cartesian3();
  var translateCVPlane = new Plane(Cartesian3.UNIT_X, 0.0);
  var translateCVStartMouse = new Cartesian2();
  var translateCVEndMouse = new Cartesian2();

  function translateCV(controller, startPosition, movement) {
    if (!Cartesian3.equals(startPosition, controller._translateMousePosition)) {
      controller._looking = false;
    }

    if (!Cartesian3.equals(startPosition, controller._strafeMousePosition)) {
      controller._strafing = false;
    }

    if (controller._looking) {
      look3D(controller, startPosition, movement);
      return;
    }

    if (controller._strafing) {
      continueStrafing(controller, movement);
      return;
    }

    var scene = controller._scene;
    var camera = scene.camera;
    var cameraUnderground = controller._cameraUnderground;
    var startMouse = Cartesian2.clone(
      movement.startPosition,
      translateCVStartMouse
    );
    var endMouse = Cartesian2.clone(movement.endPosition, translateCVEndMouse);
    var startRay = camera.getPickRay(startMouse, translateCVStartRay);

    var origin = Cartesian3.clone(Cartesian3.ZERO, translateCVOrigin);
    var normal = Cartesian3.UNIT_X;

    var globePos;
    if (camera.position.z < controller._minimumPickingTerrainHeight) {
      globePos = pickGlobe(controller, startMouse, translateCVStartPos);
      if (defined(globePos)) {
        origin.x = globePos.x;
      }
    }

    if (
      cameraUnderground ||
      (origin.x > camera.position.z && defined(globePos))
    ) {
      var pickPosition = globePos;
      if (cameraUnderground) {
        pickPosition = getStrafeStartPositionUnderground(
          controller,
          startRay,
          globePos,
          translateCVStartPos
        );
      }
      Cartesian2.clone(startPosition, controller._strafeMousePosition);
      Cartesian2.clone(startPosition, controller._strafeEndMousePosition);
      Cartesian3.clone(pickPosition, controller._strafeStartPosition);
      controller._strafing = true;
      strafe(controller, movement, controller._strafeStartPosition);
      return;
    }

    var plane = Plane.fromPointNormal(origin, normal, translateCVPlane);

    startRay = camera.getPickRay(startMouse, translateCVStartRay);
    var startPlanePos = IntersectionTests.rayPlane(
      startRay,
      plane,
      translateCVStartPos
    );

    var endRay = camera.getPickRay(endMouse, translateCVEndRay);
    var endPlanePos = IntersectionTests.rayPlane(
      endRay,
      plane,
      translateCVEndPos
    );

    if (!defined(startPlanePos) || !defined(endPlanePos)) {
      controller._looking = true;
      look3D(controller, startPosition, movement);
      Cartesian2.clone(startPosition, controller._translateMousePosition);
      return;
    }

    var diff = Cartesian3.subtract(
      startPlanePos,
      endPlanePos,
      translateCVDifference
    );
    var temp = diff.x;
    diff.x = diff.y;
    diff.y = diff.z;
    diff.z = temp;
    var mag = Cartesian3.magnitude(diff);
    if (mag > CesiumMath.EPSILON6) {
      Cartesian3.normalize(diff, diff);
      camera.move(diff, mag);
    }
  }

  var rotateCVWindowPos = new Cartesian2();
  var rotateCVWindowRay = new Ray();
  var rotateCVCenter = new Cartesian3();
  var rotateCVVerticalCenter = new Cartesian3();
  var rotateCVTransform = new Matrix4();
  var rotateCVVerticalTransform = new Matrix4();
  var rotateCVOrigin = new Cartesian3();
  var rotateCVPlane = new Plane(Cartesian3.UNIT_X, 0.0);
  var rotateCVCartesian3 = new Cartesian3();
  var rotateCVCart = new Cartographic();
  var rotateCVOldTransform = new Matrix4();
  var rotateCVQuaternion = new Quaternion();
  var rotateCVMatrix = new Matrix3();
  var tilt3DCartesian3 = new Cartesian3();

  function rotateCV(controller, startPosition, movement) {
    if (defined(movement.angleAndHeight)) {
      movement = movement.angleAndHeight;
    }

    if (!Cartesian2.equals(startPosition, controller._tiltCenterMousePosition)) {
      controller._tiltCVOffMap = false;
      controller._looking = false;
    }

    if (controller._looking) {
      look3D(controller, startPosition, movement);
      return;
    }

    var scene = controller._scene;
    var camera = scene.camera;

    if (
      controller._tiltCVOffMap ||
      !controller.onMap() ||
      Math.abs(camera.position.z) > controller._minimumPickingTerrainHeight
    ) {
      controller._tiltCVOffMap = true;
      rotateCVOnPlane(controller, startPosition, movement);
    } else {
      rotateCVOnTerrain(controller, startPosition, movement);
    }
  }

  function rotateCVOnPlane(controller, startPosition, movement) {
    var scene = controller._scene;
    var camera = scene.camera;
    var canvas = scene.canvas;

    var windowPosition = rotateCVWindowPos;
    windowPosition.x = canvas.clientWidth / 2;
    windowPosition.y = canvas.clientHeight / 2;
    var ray = camera.getPickRay(windowPosition, rotateCVWindowRay);
    var normal = Cartesian3.UNIT_X;

    var position = ray.origin;
    var direction = ray.direction;
    var scalar;
    var normalDotDirection = Cartesian3.dot(normal, direction);
    if (Math.abs(normalDotDirection) > CesiumMath.EPSILON6) {
      scalar = -Cartesian3.dot(normal, position) / normalDotDirection;
    }

    if (!defined(scalar) || scalar <= 0.0) {
      controller._looking = true;
      look3D(controller, startPosition, movement);
      Cartesian2.clone(startPosition, controller._tiltCenterMousePosition);
      return;
    }

    var center = Cartesian3.multiplyByScalar(direction, scalar, rotateCVCenter);
    Cartesian3.add(position, center, center);

    var projection = scene.mapProjection;
    var ellipsoid = projection.ellipsoid;

    Cartesian3.fromElements(center.y, center.z, center.x, center);
    var cart = projection.unproject(center, rotateCVCart);
    ellipsoid.cartographicToCartesian(cart, center);

    var transform = Transforms.eastNorthUpToFixedFrame(
      center,
      ellipsoid,
      rotateCVTransform
    );

    var oldGlobe = controller._globe;
    var oldEllipsoid = controller._ellipsoid;
    controller._globe = undefined;
    controller._ellipsoid = Ellipsoid.UNIT_SPHERE;
    controller._rotateFactor = 1.0;
    controller._rotateRateRangeAdjustment = 1.0;

    var oldTransform = Matrix4.clone(camera.transform, rotateCVOldTransform);
    camera._setTransform(transform);

    rotate3D(controller, startPosition, movement, Cartesian3.UNIT_Z);

    camera._setTransform(oldTransform);
    controller._globe = oldGlobe;
    controller._ellipsoid = oldEllipsoid;

    var radius = oldEllipsoid.maximumRadius;
    controller._rotateFactor = 1.0 / radius;
    controller._rotateRateRangeAdjustment = radius;
  }

  function rotateCVOnTerrain(controller, startPosition, movement) {
    var scene = controller._scene;
    var camera = scene.camera;
    var cameraUnderground = controller._cameraUnderground;

    var center;
    var ray;
    var normal = Cartesian3.UNIT_X;

    if (Cartesian2.equals(startPosition, controller._tiltCenterMousePosition)) {
      center = Cartesian3.clone(controller._tiltCenter, rotateCVCenter);
    } else {
      if (camera.position.z < controller._minimumPickingTerrainHeight) {
        center = pickGlobe(controller, startPosition, rotateCVCenter);
      }

      if (!defined(center)) {
        ray = camera.getPickRay(startPosition, rotateCVWindowRay);
        var position = ray.origin;
        var direction = ray.direction;

        var scalar;
        var normalDotDirection = Cartesian3.dot(normal, direction);
        if (Math.abs(normalDotDirection) > CesiumMath.EPSILON6) {
          scalar = -Cartesian3.dot(normal, position) / normalDotDirection;
        }

        if (!defined(scalar) || scalar <= 0.0) {
          controller._looking = true;
          look3D(controller, startPosition, movement);
          Cartesian2.clone(startPosition, controller._tiltCenterMousePosition);
          return;
        }

        center = Cartesian3.multiplyByScalar(direction, scalar, rotateCVCenter);
        Cartesian3.add(position, center, center);
      }

      if (cameraUnderground) {
        if (!defined(ray)) {
          ray = camera.getPickRay(startPosition, rotateCVWindowRay);
        }
        getTiltCenterUnderground(controller, ray, center, center);
      }

      Cartesian2.clone(startPosition, controller._tiltCenterMousePosition);
      Cartesian3.clone(center, controller._tiltCenter);
    }

    var canvas = scene.canvas;

    var windowPosition = rotateCVWindowPos;
    windowPosition.x = canvas.clientWidth / 2;
    windowPosition.y = controller._tiltCenterMousePosition.y;
    ray = camera.getPickRay(windowPosition, rotateCVWindowRay);

    var origin = Cartesian3.clone(Cartesian3.ZERO, rotateCVOrigin);
    origin.x = center.x;

    var plane = Plane.fromPointNormal(origin, normal, rotateCVPlane);
    var verticalCenter = IntersectionTests.rayPlane(
      ray,
      plane,
      rotateCVVerticalCenter
    );

    var projection = camera._projection;
    var ellipsoid = projection.ellipsoid;

    Cartesian3.fromElements(center.y, center.z, center.x, center);
    var cart = projection.unproject(center, rotateCVCart);
    ellipsoid.cartographicToCartesian(cart, center);

    var transform = Transforms.eastNorthUpToFixedFrame(
      center,
      ellipsoid,
      rotateCVTransform
    );

    var verticalTransform;
    if (defined(verticalCenter)) {
      Cartesian3.fromElements(
        verticalCenter.y,
        verticalCenter.z,
        verticalCenter.x,
        verticalCenter
      );
      cart = projection.unproject(verticalCenter, rotateCVCart);
      ellipsoid.cartographicToCartesian(cart, verticalCenter);

      verticalTransform = Transforms.eastNorthUpToFixedFrame(
        verticalCenter,
        ellipsoid,
        rotateCVVerticalTransform
      );
    } else {
      verticalTransform = transform;
    }

    var oldGlobe = controller._globe;
    var oldEllipsoid = controller._ellipsoid;
    controller._globe = undefined;
    controller._ellipsoid = Ellipsoid.UNIT_SPHERE;
    controller._rotateFactor = 1.0;
    controller._rotateRateRangeAdjustment = 1.0;

    var constrainedAxis = Cartesian3.UNIT_Z;

    var oldTransform = Matrix4.clone(camera.transform, rotateCVOldTransform);
    camera._setTransform(transform);

    var tangent = Cartesian3.cross(
      Cartesian3.UNIT_Z,
      Cartesian3.normalize(camera.position, rotateCVCartesian3),
      rotateCVCartesian3
    );
    var dot = Cartesian3.dot(camera.right, tangent);

    rotate3D(controller, startPosition, movement, constrainedAxis, false, true);

    camera._setTransform(verticalTransform);
    if (dot < 0.0) {
      var movementDelta = movement.startPosition.y - movement.endPosition.y;
      if (
        (cameraUnderground && movementDelta < 0.0) ||
        (!cameraUnderground && movementDelta > 0.0)
      ) {
        // Prevent camera from flipping past the up axis
        constrainedAxis = undefined;
      }

      var oldConstrainedAxis = camera.constrainedAxis;
      camera.constrainedAxis = undefined;

      rotate3D(controller, startPosition, movement, constrainedAxis, true, false);

      camera.constrainedAxis = oldConstrainedAxis;
    } else {
      rotate3D(controller, startPosition, movement, constrainedAxis, true, false);
    }

    if (defined(camera.constrainedAxis)) {
      var right = Cartesian3.cross(
        camera.direction,
        camera.constrainedAxis,
        tilt3DCartesian3
      );
      if (
        !Cartesian3.equalsEpsilon(right, Cartesian3.ZERO, CesiumMath.EPSILON6)
      ) {
        if (Cartesian3.dot(right, camera.right) < 0.0) {
          Cartesian3.negate(right, right);
        }

        Cartesian3.cross(right, camera.direction, camera.up);
        Cartesian3.cross(camera.direction, camera.up, camera.right);

        Cartesian3.normalize(camera.up, camera.up);
        Cartesian3.normalize(camera.right, camera.right);
      }
    }

    camera._setTransform(oldTransform);
    controller._globe = oldGlobe;
    controller._ellipsoid = oldEllipsoid;

    var radius = oldEllipsoid.maximumRadius;
    controller._rotateFactor = 1.0 / radius;
    controller._rotateRateRangeAdjustment = radius;

    var originalPosition = Cartesian3.clone(
      camera.positionWC,
      rotateCVCartesian3
    );

    if (controller.enableCollisionDetection) {
      adjustHeightForTerrain(controller);
    }

    if (!Cartesian3.equals(camera.positionWC, originalPosition)) {
      camera._setTransform(verticalTransform);
      camera.worldToCameraCoordinatesPoint(originalPosition, originalPosition);

      var magSqrd = Cartesian3.magnitudeSquared(originalPosition);
      if (Cartesian3.magnitudeSquared(camera.position) > magSqrd) {
        Cartesian3.normalize(camera.position, camera.position);
        Cartesian3.multiplyByScalar(
          camera.position,
          Math.sqrt(magSqrd),
          camera.position
        );
      }

      var angle = Cartesian3.angleBetween(originalPosition, camera.position);
      var axis = Cartesian3.cross(
        originalPosition,
        camera.position,
        originalPosition
      );
      Cartesian3.normalize(axis, axis);

      var quaternion = Quaternion.fromAxisAngle(axis, angle, rotateCVQuaternion);
      var rotation = Matrix3.fromQuaternion(quaternion, rotateCVMatrix);
      Matrix3.multiplyByVector(rotation, camera.direction, camera.direction);
      Matrix3.multiplyByVector(rotation, camera.up, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
      Cartesian3.cross(camera.right, camera.direction, camera.up);

      camera._setTransform(oldTransform);
    }
  }

  var zoomCVWindowPos = new Cartesian2();
  var zoomCVWindowRay = new Ray();
  var zoomCVIntersection = new Cartesian3();

  function zoomCV(controller, startPosition, movement) {
    if (defined(movement.distance)) {
      movement = movement.distance;
    }

    var scene = controller._scene;
    var camera = scene.camera;
    var canvas = scene.canvas;

    var cameraUnderground = controller._cameraUnderground;

    var windowPosition;

    if (cameraUnderground) {
      windowPosition = startPosition;
    } else {
      windowPosition = zoomCVWindowPos;
      windowPosition.x = canvas.clientWidth / 2;
      windowPosition.y = canvas.clientHeight / 2;
    }

    var ray = camera.getPickRay(windowPosition, zoomCVWindowRay);
    var position = ray.origin;
    var direction = ray.direction;
    var height = camera.position.z;

    var intersection;
    if (height < controller._minimumPickingTerrainHeight) {
      intersection = pickGlobe(controller, windowPosition, zoomCVIntersection);
    }

    var distance;
    if (defined(intersection)) {
      distance = Cartesian3.distance(position, intersection);
    }

    if (cameraUnderground) {
      var distanceUnderground = getZoomDistanceUnderground(
        controller,
        ray);
      if (defined(distance)) {
        distance = Math.min(distance, distanceUnderground);
      } else {
        distance = distanceUnderground;
      }
    }

    if (!defined(distance)) {
      var normal = Cartesian3.UNIT_X;
      distance =
        -Cartesian3.dot(normal, position) / Cartesian3.dot(normal, direction);
    }

    handleZoom(
      controller,
      startPosition,
      movement,
      controller._zoomFactor,
      distance
    );
  }

  function updateCV(controller) {
    var scene = controller._scene;
    var camera = scene.camera;

    if (!Matrix4.equals(Matrix4.IDENTITY, camera.transform)) {
      reactToInput(
        controller,
        controller.enableRotate,
        controller.rotateEventTypes,
        rotate3D,
        controller.inertiaSpin,
        "_lastInertiaSpinMovement"
      );
      reactToInput(
        controller,
        controller.enableZoom,
        controller.zoomEventTypes,
        zoom3D$1,
        controller.inertiaZoom,
        "_lastInertiaZoomMovement"
      );
    } else {
      var tweens = controller._tweens;

      if (controller._aggregator.anyButtonDown) {
        tweens.removeAll();
      }

      reactToInput(
        controller,
        controller.enableTilt,
        controller.tiltEventTypes,
        rotateCV,
        controller.inertiaSpin,
        "_lastInertiaTiltMovement"
      );
      reactToInput(
        controller,
        controller.enableTranslate,
        controller.translateEventTypes,
        translateCV,
        controller.inertiaTranslate,
        "_lastInertiaTranslateMovement"
      );
      reactToInput(
        controller,
        controller.enableZoom,
        controller.zoomEventTypes,
        zoomCV,
        controller.inertiaZoom,
        "_lastInertiaZoomMovement"
      );
      reactToInput(
        controller,
        controller.enableLook,
        controller.lookEventTypes,
        look3D
      );

      if (
        !controller._aggregator.anyButtonDown &&
        !tweens.contains(controller._tween)
      ) {
        var tween = camera.createCorrectPositionTween(
          controller.bounceAnimationTime
        );
        if (defined(tween)) {
          controller._tween = tweens.add(tween);
        }
      }

      tweens.update();
    }
  }

  var scratchStrafeRay = new Ray();
  var scratchStrafePlane = new Plane(Cartesian3.UNIT_X, 0.0);
  var scratchStrafeIntersection = new Cartesian3();
  var scratchStrafeDirection = new Cartesian3();
  var scratchMousePos = new Cartesian3();

  function strafe(controller, movement, strafeStartPosition) {
    var scene = controller._scene;
    var camera = scene.camera;

    var ray = camera.getPickRay(movement.endPosition, scratchStrafeRay);

    var direction = Cartesian3.clone(camera.direction, scratchStrafeDirection);
    if (scene.mode === SceneMode$1.COLUMBUS_VIEW) {
      Cartesian3.fromElements(direction.z, direction.x, direction.y, direction);
    }

    var plane = Plane.fromPointNormal(
      strafeStartPosition,
      direction,
      scratchStrafePlane
    );
    var intersection = IntersectionTests.rayPlane(
      ray,
      plane,
      scratchStrafeIntersection
    );
    if (!defined(intersection)) {
      return;
    }

    direction = Cartesian3.subtract(strafeStartPosition, intersection, direction);
    if (scene.mode === SceneMode$1.COLUMBUS_VIEW) {
      Cartesian3.fromElements(direction.y, direction.z, direction.x, direction);
    }

    Cartesian3.add(camera.position, direction, camera.position);
  }

  var spin3DPick = new Cartesian3();
  var scratchCartographic$f = new Cartographic();
  var scratchRadii$2 = new Cartesian3();
  var scratchEllipsoid$e = new Ellipsoid();
  var scratchLookUp = new Cartesian3();
  var scratchNormal$8 = new Cartesian3();

  function spin3D(controller, startPosition, movement) {
    var scene = controller._scene;
    var camera = scene.camera;
    var cameraUnderground = controller._cameraUnderground;
    var ellipsoid = controller._ellipsoid;

    if (!Matrix4.equals(camera.transform, Matrix4.IDENTITY)) {
      rotate3D(controller, startPosition, movement);
      return;
    }

    var magnitude;
    var radii;

    var up = ellipsoid.geodeticSurfaceNormal(camera.position, scratchLookUp);

    if (Cartesian2.equals(startPosition, controller._rotateMousePosition)) {
      if (controller._looking) {
        look3D(controller, startPosition, movement, up);
      } else if (controller._rotating) {
        rotate3D(controller, startPosition, movement);
      } else if (controller._strafing) {
        continueStrafing(controller, movement);
      } else {
        if (
          Cartesian3.magnitude(camera.position) <
          Cartesian3.magnitude(controller._rotateStartPosition)
        ) {
          // Pan action is no longer valid if camera moves below the pan ellipsoid
          return;
        }
        magnitude = Cartesian3.magnitude(controller._rotateStartPosition);
        radii = scratchRadii$2;
        radii.x = radii.y = radii.z = magnitude;
        ellipsoid = Ellipsoid.fromCartesian3(radii, scratchEllipsoid$e);
        pan3D(controller, startPosition, movement, ellipsoid);
      }
      return;
    }
    controller._looking = false;
    controller._rotating = false;
    controller._strafing = false;

    var height = ellipsoid.cartesianToCartographic(
      camera.positionWC,
      scratchCartographic$f
    ).height;
    var globe = controller._globe;

    if (defined(globe) && height < controller._minimumPickingTerrainHeight) {
      var mousePos = pickGlobe(
        controller,
        movement.startPosition,
        scratchMousePos
      );
      if (defined(mousePos)) {
        var strafing = false;
        var ray = camera.getPickRay(movement.startPosition, pickGlobeScratchRay);

        if (cameraUnderground) {
          strafing = true;
          getStrafeStartPositionUnderground(controller, ray, mousePos, mousePos);
        } else {
          var normal = ellipsoid.geodeticSurfaceNormal(mousePos, scratchNormal$8);
          var tangentPick =
            Math.abs(Cartesian3.dot(ray.direction, normal)) < 0.05;

          if (tangentPick) {
            strafing = true;
          } else {
            strafing =
              Cartesian3.magnitude(camera.position) <
              Cartesian3.magnitude(mousePos);
          }
        }

        if (strafing) {
          Cartesian2.clone(startPosition, controller._strafeEndMousePosition);
          Cartesian3.clone(mousePos, controller._strafeStartPosition);
          controller._strafing = true;
          strafe(controller, movement, controller._strafeStartPosition);
        } else {
          magnitude = Cartesian3.magnitude(mousePos);
          radii = scratchRadii$2;
          radii.x = radii.y = radii.z = magnitude;
          ellipsoid = Ellipsoid.fromCartesian3(radii, scratchEllipsoid$e);
          pan3D(controller, startPosition, movement, ellipsoid);

          Cartesian3.clone(mousePos, controller._rotateStartPosition);
        }
      } else {
        controller._looking = true;
        look3D(controller, startPosition, movement, up);
      }
    } else if (
      defined(
        camera.pickEllipsoid(
          movement.startPosition,
          controller._ellipsoid,
          spin3DPick
        )
      )
    ) {
      pan3D(controller, startPosition, movement, controller._ellipsoid);
      Cartesian3.clone(spin3DPick, controller._rotateStartPosition);
    } else if (height > controller._minimumTrackBallHeight) {
      controller._rotating = true;
      rotate3D(controller, startPosition, movement);
    } else {
      controller._looking = true;
      look3D(controller, startPosition, movement, up);
    }

    Cartesian2.clone(startPosition, controller._rotateMousePosition);
  }

  function rotate3D(
    controller,
    startPosition,
    movement,
    constrainedAxis,
    rotateOnlyVertical,
    rotateOnlyHorizontal
  ) {
    rotateOnlyVertical = defaultValue(rotateOnlyVertical, false);
    rotateOnlyHorizontal = defaultValue(rotateOnlyHorizontal, false);

    var scene = controller._scene;
    var camera = scene.camera;
    var canvas = scene.canvas;

    var oldAxis = camera.constrainedAxis;
    if (defined(constrainedAxis)) {
      camera.constrainedAxis = constrainedAxis;
    }

    var rho = Cartesian3.magnitude(camera.position);
    var rotateRate =
      controller._rotateFactor * (rho - controller._rotateRateRangeAdjustment);

    if (rotateRate > controller._maximumRotateRate) {
      rotateRate = controller._maximumRotateRate;
    }

    if (rotateRate < controller._minimumRotateRate) {
      rotateRate = controller._minimumRotateRate;
    }

    var phiWindowRatio =
      (movement.startPosition.x - movement.endPosition.x) / canvas.clientWidth;
    var thetaWindowRatio =
      (movement.startPosition.y - movement.endPosition.y) / canvas.clientHeight;
    phiWindowRatio = Math.min(phiWindowRatio, controller.maximumMovementRatio);
    thetaWindowRatio = Math.min(
      thetaWindowRatio,
      controller.maximumMovementRatio
    );

    var deltaPhi = rotateRate * phiWindowRatio * Math.PI * 2.0;
    var deltaTheta = rotateRate * thetaWindowRatio * Math.PI;

    if (!rotateOnlyVertical) {
      camera.rotateRight(deltaPhi);
    }

    if (!rotateOnlyHorizontal) {
      camera.rotateUp(deltaTheta);
    }

    camera.constrainedAxis = oldAxis;
  }

  var pan3DP0 = Cartesian4.clone(Cartesian4.UNIT_W);
  var pan3DP1 = Cartesian4.clone(Cartesian4.UNIT_W);
  var pan3DTemp0 = new Cartesian3();
  var pan3DTemp1 = new Cartesian3();
  var pan3DTemp2 = new Cartesian3();
  var pan3DTemp3 = new Cartesian3();
  var pan3DStartMousePosition = new Cartesian2();
  var pan3DEndMousePosition = new Cartesian2();

  function pan3D(controller, startPosition, movement, ellipsoid) {
    var scene = controller._scene;
    var camera = scene.camera;

    var startMousePosition = Cartesian2.clone(
      movement.startPosition,
      pan3DStartMousePosition
    );
    var endMousePosition = Cartesian2.clone(
      movement.endPosition,
      pan3DEndMousePosition
    );

    var p0 = camera.pickEllipsoid(startMousePosition, ellipsoid, pan3DP0);
    var p1 = camera.pickEllipsoid(endMousePosition, ellipsoid, pan3DP1);

    if (!defined(p0) || !defined(p1)) {
      controller._rotating = true;
      rotate3D(controller, startPosition, movement);
      return;
    }

    p0 = camera.worldToCameraCoordinates(p0, p0);
    p1 = camera.worldToCameraCoordinates(p1, p1);

    if (!defined(camera.constrainedAxis)) {
      Cartesian3.normalize(p0, p0);
      Cartesian3.normalize(p1, p1);
      var dot = Cartesian3.dot(p0, p1);
      var axis = Cartesian3.cross(p0, p1, pan3DTemp0);

      if (
        dot < 1.0 &&
        !Cartesian3.equalsEpsilon(axis, Cartesian3.ZERO, CesiumMath.EPSILON14)
      ) {
        // dot is in [0, 1]
        var angle = Math.acos(dot);
        camera.rotate(axis, angle);
      }
    } else {
      var basis0 = camera.constrainedAxis;
      var basis1 = Cartesian3.mostOrthogonalAxis(basis0, pan3DTemp0);
      Cartesian3.cross(basis1, basis0, basis1);
      Cartesian3.normalize(basis1, basis1);
      var basis2 = Cartesian3.cross(basis0, basis1, pan3DTemp1);

      var startRho = Cartesian3.magnitude(p0);
      var startDot = Cartesian3.dot(basis0, p0);
      var startTheta = Math.acos(startDot / startRho);
      var startRej = Cartesian3.multiplyByScalar(basis0, startDot, pan3DTemp2);
      Cartesian3.subtract(p0, startRej, startRej);
      Cartesian3.normalize(startRej, startRej);

      var endRho = Cartesian3.magnitude(p1);
      var endDot = Cartesian3.dot(basis0, p1);
      var endTheta = Math.acos(endDot / endRho);
      var endRej = Cartesian3.multiplyByScalar(basis0, endDot, pan3DTemp3);
      Cartesian3.subtract(p1, endRej, endRej);
      Cartesian3.normalize(endRej, endRej);

      var startPhi = Math.acos(Cartesian3.dot(startRej, basis1));
      if (Cartesian3.dot(startRej, basis2) < 0) {
        startPhi = CesiumMath.TWO_PI - startPhi;
      }

      var endPhi = Math.acos(Cartesian3.dot(endRej, basis1));
      if (Cartesian3.dot(endRej, basis2) < 0) {
        endPhi = CesiumMath.TWO_PI - endPhi;
      }

      var deltaPhi = startPhi - endPhi;

      var east;
      if (
        Cartesian3.equalsEpsilon(basis0, camera.position, CesiumMath.EPSILON2)
      ) {
        east = camera.right;
      } else {
        east = Cartesian3.cross(basis0, camera.position, pan3DTemp0);
      }

      var planeNormal = Cartesian3.cross(basis0, east, pan3DTemp0);
      var side0 = Cartesian3.dot(
        planeNormal,
        Cartesian3.subtract(p0, basis0, pan3DTemp1)
      );
      var side1 = Cartesian3.dot(
        planeNormal,
        Cartesian3.subtract(p1, basis0, pan3DTemp1)
      );

      var deltaTheta;
      if (side0 > 0 && side1 > 0) {
        deltaTheta = endTheta - startTheta;
      } else if (side0 > 0 && side1 <= 0) {
        if (Cartesian3.dot(camera.position, basis0) > 0) {
          deltaTheta = -startTheta - endTheta;
        } else {
          deltaTheta = startTheta + endTheta;
        }
      } else {
        deltaTheta = startTheta - endTheta;
      }

      camera.rotateRight(deltaPhi);
      camera.rotateUp(deltaTheta);
    }
  }

  var zoom3DUnitPosition = new Cartesian3();
  var zoom3DCartographic = new Cartographic();

  function zoom3D$1(controller, startPosition, movement) {
    if (defined(movement.distance)) {
      movement = movement.distance;
    }

    var ellipsoid = controller._ellipsoid;
    var scene = controller._scene;
    var camera = scene.camera;
    var canvas = scene.canvas;

    var cameraUnderground = controller._cameraUnderground;

    var windowPosition;

    if (cameraUnderground) {
      windowPosition = startPosition;
    } else {
      windowPosition = zoomCVWindowPos;
      windowPosition.x = canvas.clientWidth / 2;
      windowPosition.y = canvas.clientHeight / 2;
    }

    var ray = camera.getPickRay(windowPosition, zoomCVWindowRay);

    var intersection;
    var height = ellipsoid.cartesianToCartographic(
      camera.position,
      zoom3DCartographic
    ).height;
    if (height < controller._minimumPickingTerrainHeight) {
      intersection = pickGlobe(controller, windowPosition, zoomCVIntersection);
    }

    var distance;
    if (defined(intersection)) {
      distance = Cartesian3.distance(ray.origin, intersection);
    }

    if (cameraUnderground) {
      var distanceUnderground = getZoomDistanceUnderground(
        controller,
        ray);
      if (defined(distance)) {
        distance = Math.min(distance, distanceUnderground);
      } else {
        distance = distanceUnderground;
      }
    }

    if (!defined(distance)) {
      distance = height;
    }

    var unitPosition = Cartesian3.normalize(camera.position, zoom3DUnitPosition);
    handleZoom(
      controller,
      startPosition,
      movement,
      controller._zoomFactor,
      distance,
      Cartesian3.dot(unitPosition, camera.direction)
    );
  }

  var tilt3DWindowPos = new Cartesian2();
  var tilt3DRay = new Ray();
  var tilt3DCenter = new Cartesian3();
  var tilt3DVerticalCenter = new Cartesian3();
  var tilt3DTransform = new Matrix4();
  var tilt3DVerticalTransform = new Matrix4();
  var tilt3DOldTransform = new Matrix4();
  var tilt3DQuaternion = new Quaternion();
  var tilt3DMatrix = new Matrix3();
  var tilt3DCart = new Cartographic();
  var tilt3DLookUp = new Cartesian3();

  function tilt3D(controller, startPosition, movement) {
    var scene = controller._scene;
    var camera = scene.camera;

    if (!Matrix4.equals(camera.transform, Matrix4.IDENTITY)) {
      return;
    }

    if (defined(movement.angleAndHeight)) {
      movement = movement.angleAndHeight;
    }

    if (!Cartesian2.equals(startPosition, controller._tiltCenterMousePosition)) {
      controller._tiltOnEllipsoid = false;
      controller._looking = false;
    }

    if (controller._looking) {
      var up = controller._ellipsoid.geodeticSurfaceNormal(
        camera.position,
        tilt3DLookUp
      );
      look3D(controller, startPosition, movement, up);
      return;
    }

    var ellipsoid = controller._ellipsoid;
    var cartographic = ellipsoid.cartesianToCartographic(
      camera.position,
      tilt3DCart
    );

    if (
      controller._tiltOnEllipsoid ||
      cartographic.height > controller._minimumCollisionTerrainHeight
    ) {
      controller._tiltOnEllipsoid = true;
      tilt3DOnEllipsoid(controller, startPosition, movement);
    } else {
      tilt3DOnTerrain(controller, startPosition, movement);
    }
  }

  var tilt3DOnEllipsoidCartographic = new Cartographic();

  function tilt3DOnEllipsoid(controller, startPosition, movement) {
    var ellipsoid = controller._ellipsoid;
    var scene = controller._scene;
    var camera = scene.camera;
    var minHeight = controller.minimumZoomDistance * 0.25;
    var height = ellipsoid.cartesianToCartographic(
      camera.positionWC,
      tilt3DOnEllipsoidCartographic
    ).height;
    if (
      height - minHeight - 1.0 < CesiumMath.EPSILON3 &&
      movement.endPosition.y - movement.startPosition.y < 0
    ) {
      return;
    }

    var canvas = scene.canvas;

    var windowPosition = tilt3DWindowPos;
    windowPosition.x = canvas.clientWidth / 2;
    windowPosition.y = canvas.clientHeight / 2;
    var ray = camera.getPickRay(windowPosition, tilt3DRay);

    var center;
    var intersection = IntersectionTests.rayEllipsoid(ray, ellipsoid);
    if (defined(intersection)) {
      center = Ray.getPoint(ray, intersection.start, tilt3DCenter);
    } else if (height > controller._minimumTrackBallHeight) {
      var grazingAltitudeLocation = IntersectionTests.grazingAltitudeLocation(
        ray,
        ellipsoid
      );
      if (!defined(grazingAltitudeLocation)) {
        return;
      }
      var grazingAltitudeCart = ellipsoid.cartesianToCartographic(
        grazingAltitudeLocation,
        tilt3DCart
      );
      grazingAltitudeCart.height = 0.0;
      center = ellipsoid.cartographicToCartesian(
        grazingAltitudeCart,
        tilt3DCenter
      );
    } else {
      controller._looking = true;
      var up = controller._ellipsoid.geodeticSurfaceNormal(
        camera.position,
        tilt3DLookUp
      );
      look3D(controller, startPosition, movement, up);
      Cartesian2.clone(startPosition, controller._tiltCenterMousePosition);
      return;
    }

    var transform = Transforms.eastNorthUpToFixedFrame(
      center,
      ellipsoid,
      tilt3DTransform
    );

    var oldGlobe = controller._globe;
    var oldEllipsoid = controller._ellipsoid;
    controller._globe = undefined;
    controller._ellipsoid = Ellipsoid.UNIT_SPHERE;
    controller._rotateFactor = 1.0;
    controller._rotateRateRangeAdjustment = 1.0;

    var oldTransform = Matrix4.clone(camera.transform, tilt3DOldTransform);
    camera._setTransform(transform);

    rotate3D(controller, startPosition, movement, Cartesian3.UNIT_Z);

    camera._setTransform(oldTransform);
    controller._globe = oldGlobe;
    controller._ellipsoid = oldEllipsoid;

    var radius = oldEllipsoid.maximumRadius;
    controller._rotateFactor = 1.0 / radius;
    controller._rotateRateRangeAdjustment = radius;
  }

  function tilt3DOnTerrain(controller, startPosition, movement) {
    var ellipsoid = controller._ellipsoid;
    var scene = controller._scene;
    var camera = scene.camera;
    var cameraUnderground = controller._cameraUnderground;

    var center;
    var ray;
    var intersection;

    if (Cartesian2.equals(startPosition, controller._tiltCenterMousePosition)) {
      center = Cartesian3.clone(controller._tiltCenter, tilt3DCenter);
    } else {
      center = pickGlobe(controller, startPosition, tilt3DCenter);

      if (!defined(center)) {
        ray = camera.getPickRay(startPosition, tilt3DRay);
        intersection = IntersectionTests.rayEllipsoid(ray, ellipsoid);
        if (!defined(intersection)) {
          var cartographic = ellipsoid.cartesianToCartographic(
            camera.position,
            tilt3DCart
          );
          if (cartographic.height <= controller._minimumTrackBallHeight) {
            controller._looking = true;
            var up = controller._ellipsoid.geodeticSurfaceNormal(
              camera.position,
              tilt3DLookUp
            );
            look3D(controller, startPosition, movement, up);
            Cartesian2.clone(startPosition, controller._tiltCenterMousePosition);
          }
          return;
        }
        center = Ray.getPoint(ray, intersection.start, tilt3DCenter);
      }

      if (cameraUnderground) {
        if (!defined(ray)) {
          ray = camera.getPickRay(startPosition, tilt3DRay);
        }
        getTiltCenterUnderground(controller, ray, center, center);
      }

      Cartesian2.clone(startPosition, controller._tiltCenterMousePosition);
      Cartesian3.clone(center, controller._tiltCenter);
    }

    var canvas = scene.canvas;

    var windowPosition = tilt3DWindowPos;
    windowPosition.x = canvas.clientWidth / 2;
    windowPosition.y = controller._tiltCenterMousePosition.y;
    ray = camera.getPickRay(windowPosition, tilt3DRay);

    var mag = Cartesian3.magnitude(center);
    var radii = Cartesian3.fromElements(mag, mag, mag, scratchRadii$2);
    var newEllipsoid = Ellipsoid.fromCartesian3(radii, scratchEllipsoid$e);

    intersection = IntersectionTests.rayEllipsoid(ray, newEllipsoid);
    if (!defined(intersection)) {
      return;
    }

    var t =
      Cartesian3.magnitude(ray.origin) > mag
        ? intersection.start
        : intersection.stop;
    var verticalCenter = Ray.getPoint(ray, t, tilt3DVerticalCenter);

    var transform = Transforms.eastNorthUpToFixedFrame(
      center,
      ellipsoid,
      tilt3DTransform
    );
    var verticalTransform = Transforms.eastNorthUpToFixedFrame(
      verticalCenter,
      newEllipsoid,
      tilt3DVerticalTransform
    );

    var oldGlobe = controller._globe;
    var oldEllipsoid = controller._ellipsoid;
    controller._globe = undefined;
    controller._ellipsoid = Ellipsoid.UNIT_SPHERE;
    controller._rotateFactor = 1.0;
    controller._rotateRateRangeAdjustment = 1.0;

    var constrainedAxis = Cartesian3.UNIT_Z;

    var oldTransform = Matrix4.clone(camera.transform, tilt3DOldTransform);
    camera._setTransform(transform);

    var tangent = Cartesian3.cross(
      verticalCenter,
      camera.positionWC,
      tilt3DCartesian3
    );
    var dot = Cartesian3.dot(camera.rightWC, tangent);

    rotate3D(controller, startPosition, movement, constrainedAxis, false, true);

    camera._setTransform(verticalTransform);

    if (dot < 0.0) {
      var movementDelta = movement.startPosition.y - movement.endPosition.y;
      if (
        (cameraUnderground && movementDelta < 0.0) ||
        (!cameraUnderground && movementDelta > 0.0)
      ) {
        // Prevent camera from flipping past the up axis
        constrainedAxis = undefined;
      }

      var oldConstrainedAxis = camera.constrainedAxis;
      camera.constrainedAxis = undefined;

      rotate3D(controller, startPosition, movement, constrainedAxis, true, false);

      camera.constrainedAxis = oldConstrainedAxis;
    } else {
      rotate3D(controller, startPosition, movement, constrainedAxis, true, false);
    }

    if (defined(camera.constrainedAxis)) {
      var right = Cartesian3.cross(
        camera.direction,
        camera.constrainedAxis,
        tilt3DCartesian3
      );
      if (
        !Cartesian3.equalsEpsilon(right, Cartesian3.ZERO, CesiumMath.EPSILON6)
      ) {
        if (Cartesian3.dot(right, camera.right) < 0.0) {
          Cartesian3.negate(right, right);
        }

        Cartesian3.cross(right, camera.direction, camera.up);
        Cartesian3.cross(camera.direction, camera.up, camera.right);

        Cartesian3.normalize(camera.up, camera.up);
        Cartesian3.normalize(camera.right, camera.right);
      }
    }

    camera._setTransform(oldTransform);
    controller._globe = oldGlobe;
    controller._ellipsoid = oldEllipsoid;

    var radius = oldEllipsoid.maximumRadius;
    controller._rotateFactor = 1.0 / radius;
    controller._rotateRateRangeAdjustment = radius;

    var originalPosition = Cartesian3.clone(camera.positionWC, tilt3DCartesian3);

    if (controller.enableCollisionDetection) {
      adjustHeightForTerrain(controller);
    }

    if (!Cartesian3.equals(camera.positionWC, originalPosition)) {
      camera._setTransform(verticalTransform);
      camera.worldToCameraCoordinatesPoint(originalPosition, originalPosition);

      var magSqrd = Cartesian3.magnitudeSquared(originalPosition);
      if (Cartesian3.magnitudeSquared(camera.position) > magSqrd) {
        Cartesian3.normalize(camera.position, camera.position);
        Cartesian3.multiplyByScalar(
          camera.position,
          Math.sqrt(magSqrd),
          camera.position
        );
      }

      var angle = Cartesian3.angleBetween(originalPosition, camera.position);
      var axis = Cartesian3.cross(
        originalPosition,
        camera.position,
        originalPosition
      );
      Cartesian3.normalize(axis, axis);

      var quaternion = Quaternion.fromAxisAngle(axis, angle, tilt3DQuaternion);
      var rotation = Matrix3.fromQuaternion(quaternion, tilt3DMatrix);
      Matrix3.multiplyByVector(rotation, camera.direction, camera.direction);
      Matrix3.multiplyByVector(rotation, camera.up, camera.up);
      Cartesian3.cross(camera.direction, camera.up, camera.right);
      Cartesian3.cross(camera.right, camera.direction, camera.up);

      camera._setTransform(oldTransform);
    }
  }

  var look3DStartPos = new Cartesian2();
  var look3DEndPos = new Cartesian2();
  var look3DStartRay = new Ray();
  var look3DEndRay = new Ray();
  var look3DNegativeRot = new Cartesian3();
  var look3DTan = new Cartesian3();

  function look3D(controller, startPosition, movement, rotationAxis) {
    var scene = controller._scene;
    var camera = scene.camera;

    var startPos = look3DStartPos;
    startPos.x = movement.startPosition.x;
    startPos.y = 0.0;
    var endPos = look3DEndPos;
    endPos.x = movement.endPosition.x;
    endPos.y = 0.0;

    var startRay = camera.getPickRay(startPos, look3DStartRay);
    var endRay = camera.getPickRay(endPos, look3DEndRay);
    var angle = 0.0;
    var start;
    var end;

    if (camera.frustum instanceof OrthographicFrustum) {
      start = startRay.origin;
      end = endRay.origin;

      Cartesian3.add(camera.direction, start, start);
      Cartesian3.add(camera.direction, end, end);

      Cartesian3.subtract(start, camera.position, start);
      Cartesian3.subtract(end, camera.position, end);

      Cartesian3.normalize(start, start);
      Cartesian3.normalize(end, end);
    } else {
      start = startRay.direction;
      end = endRay.direction;
    }

    var dot = Cartesian3.dot(start, end);
    if (dot < 1.0) {
      // dot is in [0, 1]
      angle = Math.acos(dot);
    }

    angle = movement.startPosition.x > movement.endPosition.x ? -angle : angle;

    var horizontalRotationAxis = controller._horizontalRotationAxis;
    if (defined(rotationAxis)) {
      camera.look(rotationAxis, -angle);
    } else if (defined(horizontalRotationAxis)) {
      camera.look(horizontalRotationAxis, -angle);
    } else {
      camera.lookLeft(angle);
    }

    startPos.x = 0.0;
    startPos.y = movement.startPosition.y;
    endPos.x = 0.0;
    endPos.y = movement.endPosition.y;

    startRay = camera.getPickRay(startPos, look3DStartRay);
    endRay = camera.getPickRay(endPos, look3DEndRay);
    angle = 0.0;

    if (camera.frustum instanceof OrthographicFrustum) {
      start = startRay.origin;
      end = endRay.origin;

      Cartesian3.add(camera.direction, start, start);
      Cartesian3.add(camera.direction, end, end);

      Cartesian3.subtract(start, camera.position, start);
      Cartesian3.subtract(end, camera.position, end);

      Cartesian3.normalize(start, start);
      Cartesian3.normalize(end, end);
    } else {
      start = startRay.direction;
      end = endRay.direction;
    }

    dot = Cartesian3.dot(start, end);
    if (dot < 1.0) {
      // dot is in [0, 1]
      angle = Math.acos(dot);
    }
    angle = movement.startPosition.y > movement.endPosition.y ? -angle : angle;

    rotationAxis = defaultValue(rotationAxis, horizontalRotationAxis);
    if (defined(rotationAxis)) {
      var direction = camera.direction;
      var negativeRotationAxis = Cartesian3.negate(
        rotationAxis,
        look3DNegativeRot
      );
      var northParallel = Cartesian3.equalsEpsilon(
        direction,
        rotationAxis,
        CesiumMath.EPSILON2
      );
      var southParallel = Cartesian3.equalsEpsilon(
        direction,
        negativeRotationAxis,
        CesiumMath.EPSILON2
      );
      if (!northParallel && !southParallel) {
        dot = Cartesian3.dot(direction, rotationAxis);
        var angleToAxis = CesiumMath.acosClamped(dot);
        if (angle > 0 && angle > angleToAxis) {
          angle = angleToAxis - CesiumMath.EPSILON4;
        }

        dot = Cartesian3.dot(direction, negativeRotationAxis);
        angleToAxis = CesiumMath.acosClamped(dot);
        if (angle < 0 && -angle > angleToAxis) {
          angle = -angleToAxis + CesiumMath.EPSILON4;
        }

        var tangent = Cartesian3.cross(rotationAxis, direction, look3DTan);
        camera.look(tangent, angle);
      } else if ((northParallel && angle < 0) || (southParallel && angle > 0)) {
        camera.look(camera.right, -angle);
      }
    } else {
      camera.lookUp(angle);
    }
  }

  function update3D(controller) {
    reactToInput(
      controller,
      controller.enableRotate,
      controller.rotateEventTypes,
      spin3D,
      controller.inertiaSpin,
      "_lastInertiaSpinMovement"
    );
    reactToInput(
      controller,
      controller.enableZoom,
      controller.zoomEventTypes,
      zoom3D$1,
      controller.inertiaZoom,
      "_lastInertiaZoomMovement"
    );
    reactToInput(
      controller,
      controller.enableTilt,
      controller.tiltEventTypes,
      tilt3D,
      controller.inertiaSpin,
      "_lastInertiaTiltMovement"
    );
    reactToInput(
      controller,
      controller.enableLook,
      controller.lookEventTypes,
      look3D
    );
  }

  var scratchAdjustHeightTransform = new Matrix4();
  var scratchAdjustHeightCartographic = new Cartographic();

  function adjustHeightForTerrain(controller) {
    controller._adjustedHeightForTerrain = true;

    var scene = controller._scene;
    var mode = scene.mode;
    var globe = scene.globe;

    if (
      !defined(globe) ||
      mode === SceneMode$1.SCENE2D ||
      mode === SceneMode$1.MORPHING
    ) {
      return;
    }

    var camera = scene.camera;
    var ellipsoid = globe.ellipsoid;
    var projection = scene.mapProjection;

    var transform;
    var mag;
    if (!Matrix4.equals(camera.transform, Matrix4.IDENTITY)) {
      transform = Matrix4.clone(camera.transform, scratchAdjustHeightTransform);
      mag = Cartesian3.magnitude(camera.position);
      camera._setTransform(Matrix4.IDENTITY);
    }

    var cartographic = scratchAdjustHeightCartographic;
    if (mode === SceneMode$1.SCENE3D) {
      ellipsoid.cartesianToCartographic(camera.position, cartographic);
    } else {
      projection.unproject(camera.position, cartographic);
    }

    var heightUpdated = false;
    if (cartographic.height < controller._minimumCollisionTerrainHeight) {
      var globeHeight = controller._scene.globeHeight;
      if (defined(globeHeight)) {
        var height = globeHeight + controller.minimumZoomDistance;
        if (cartographic.height < height) {
          cartographic.height = height;
          if (mode === SceneMode$1.SCENE3D) {
            ellipsoid.cartographicToCartesian(cartographic, camera.position);
          } else {
            projection.project(cartographic, camera.position);
          }
          heightUpdated = true;
        }
      }
    }

    if (defined(transform)) {
      camera._setTransform(transform);
      if (heightUpdated) {
        Cartesian3.normalize(camera.position, camera.position);
        Cartesian3.negate(camera.position, camera.direction);
        Cartesian3.multiplyByScalar(
          camera.position,
          Math.max(mag, controller.minimumZoomDistance),
          camera.position
        );
        Cartesian3.normalize(camera.direction, camera.direction);
        Cartesian3.cross(camera.direction, camera.up, camera.right);
        Cartesian3.cross(camera.right, camera.direction, camera.up);
      }
    }
  }

  /**
   * @private
   */
  ScreenSpaceCameraController.prototype.onMap = function () {
    var scene = this._scene;
    var mode = scene.mode;
    var camera = scene.camera;

    if (mode === SceneMode$1.COLUMBUS_VIEW) {
      return (
        Math.abs(camera.position.x) - this._maxCoord.x < 0 &&
        Math.abs(camera.position.y) - this._maxCoord.y < 0
      );
    }

    return true;
  };

  var scratchPreviousPosition = new Cartesian3();
  var scratchPreviousDirection = new Cartesian3();

  /**
   * @private
   */
  ScreenSpaceCameraController.prototype.update = function () {
    var scene = this._scene;
    var camera = scene.camera;
    var globe = scene.globe;
    var mode = scene.mode;

    if (!Matrix4.equals(camera.transform, Matrix4.IDENTITY)) {
      this._globe = undefined;
      this._ellipsoid = Ellipsoid.UNIT_SPHERE;
    } else {
      this._globe = globe;
      this._ellipsoid = defined(this._globe)
        ? this._globe.ellipsoid
        : scene.mapProjection.ellipsoid;
    }

    this._cameraUnderground = scene.cameraUnderground && defined(this._globe);

    this._minimumCollisionTerrainHeight =
      this.minimumCollisionTerrainHeight * scene.terrainExaggeration;
    this._minimumPickingTerrainHeight =
      this.minimumPickingTerrainHeight * scene.terrainExaggeration;
    this._minimumTrackBallHeight =
      this.minimumTrackBallHeight * scene.terrainExaggeration;

    var radius = this._ellipsoid.maximumRadius;
    this._rotateFactor = 1.0 / radius;
    this._rotateRateRangeAdjustment = radius;

    this._adjustedHeightForTerrain = false;
    var previousPosition = Cartesian3.clone(
      camera.positionWC,
      scratchPreviousPosition
    );
    var previousDirection = Cartesian3.clone(
      camera.directionWC,
      scratchPreviousDirection
    );

    if (mode === SceneMode$1.SCENE2D) {
      update2D(this);
    } else if (mode === SceneMode$1.COLUMBUS_VIEW) {
      this._horizontalRotationAxis = Cartesian3.UNIT_Z;
      updateCV(this);
    } else if (mode === SceneMode$1.SCENE3D) {
      this._horizontalRotationAxis = undefined;
      update3D(this);
    }

    if (this.enableCollisionDetection && !this._adjustedHeightForTerrain) {
      // Adjust the camera height if the camera moved at all (user input or inertia) and an action didn't already adjust the camera height
      var cameraChanged =
        !Cartesian3.equals(previousPosition, camera.positionWC) ||
        !Cartesian3.equals(previousDirection, camera.directionWC);
      if (cameraChanged) {
        adjustHeightForTerrain(this);
      }
    }

    this._aggregator.reset();
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see ScreenSpaceCameraController#destroy
   */
  ScreenSpaceCameraController.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Removes mouse listeners held by this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * controller = controller && controller.destroy();
   *
   * @see ScreenSpaceCameraController#isDestroyed
   */
  ScreenSpaceCameraController.prototype.destroy = function () {
    this._tweens.removeAll();
    this._aggregator = this._aggregator && this._aggregator.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var AdditiveBlend = "uniform sampler2D colorTexture;\n\
uniform sampler2D colorTexture2;\n\
uniform vec2 center;\n\
uniform float radius;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
vec4 color0 = texture2D(colorTexture, v_textureCoordinates);\n\
vec4 color1 = texture2D(colorTexture2, v_textureCoordinates);\n\
float x = length(gl_FragCoord.xy - center) / radius;\n\
float t = smoothstep(0.5, 0.8, x);\n\
gl_FragColor = mix(color0 + color1, color1, t);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var BrightPass = "uniform sampler2D colorTexture;\n\
uniform float avgLuminance;\n\
uniform float threshold;\n\
uniform float offset;\n\
varying vec2 v_textureCoordinates;\n\
float key(float avg)\n\
{\n\
float guess = 1.5 - (1.5 / (avg * 0.1 + 1.0));\n\
return max(0.0, guess) + 0.1;\n\
}\n\
void main()\n\
{\n\
vec4 color = texture2D(colorTexture, v_textureCoordinates);\n\
vec3 xyz = czm_RGBToXYZ(color.rgb);\n\
float luminance = xyz.r;\n\
float scaledLum = key(avgLuminance) * luminance / avgLuminance;\n\
float brightLum = max(scaledLum - threshold, 0.0);\n\
float brightness = brightLum / (offset + brightLum);\n\
xyz.r = brightness;\n\
gl_FragColor = vec4(czm_XYZToRGB(xyz), 1.0);\n\
}\n\
";

  function SunPostProcess() {
    this._sceneFramebuffer = new SceneFramebuffer();

    var scale = 0.125;
    var stages = new Array(6);

    stages[0] = new PostProcessStage({
      fragmentShader: PassThrough,
      textureScale: scale,
      forcePowerOfTwo: true,
      sampleMode: PostProcessStageSampleMode.LINEAR,
    });

    var brightPass = (stages[1] = new PostProcessStage({
      fragmentShader: BrightPass,
      uniforms: {
        avgLuminance: 0.5, // A guess at the average luminance across the entire scene
        threshold: 0.25,
        offset: 0.1,
      },
      textureScale: scale,
      forcePowerOfTwo: true,
    }));

    var that = this;
    this._delta = 1.0;
    this._sigma = 2.0;
    this._blurStep = new Cartesian2();

    stages[2] = new PostProcessStage({
      fragmentShader: GaussianBlur1D,
      uniforms: {
        step: function () {
          that._blurStep.x = that._blurStep.y =
            1.0 / brightPass.outputTexture.width;
          return that._blurStep;
        },
        delta: function () {
          return that._delta;
        },
        sigma: function () {
          return that._sigma;
        },
        direction: 0.0,
      },
      textureScale: scale,
      forcePowerOfTwo: true,
    });

    stages[3] = new PostProcessStage({
      fragmentShader: GaussianBlur1D,
      uniforms: {
        step: function () {
          that._blurStep.x = that._blurStep.y =
            1.0 / brightPass.outputTexture.width;
          return that._blurStep;
        },
        delta: function () {
          return that._delta;
        },
        sigma: function () {
          return that._sigma;
        },
        direction: 1.0,
      },
      textureScale: scale,
      forcePowerOfTwo: true,
    });

    stages[4] = new PostProcessStage({
      fragmentShader: PassThrough,
      sampleMode: PostProcessStageSampleMode.LINEAR,
    });

    this._uCenter = new Cartesian2();
    this._uRadius = undefined;

    stages[5] = new PostProcessStage({
      fragmentShader: AdditiveBlend,
      uniforms: {
        center: function () {
          return that._uCenter;
        },
        radius: function () {
          return that._uRadius;
        },
        colorTexture2: function () {
          return that._sceneFramebuffer.getFramebuffer().getColorTexture(0);
        },
      },
    });

    this._stages = new PostProcessStageComposite({
      stages: stages,
    });

    var textureCache = new PostProcessStageTextureCache(this);
    var length = stages.length;
    for (var i = 0; i < length; ++i) {
      stages[i]._textureCache = textureCache;
    }

    this._textureCache = textureCache;
    this.length = stages.length;
  }

  SunPostProcess.prototype.get = function (index) {
    return this._stages.get(index);
  };

  SunPostProcess.prototype.getStageByName = function (name) {
    var length = this._stages.length;
    for (var i = 0; i < length; ++i) {
      var stage = this._stages.get(i);
      if (stage.name === name) {
        return stage;
      }
    }
    return undefined;
  };

  var sunPositionECScratch = new Cartesian4();
  var sunPositionWCScratch = new Cartesian2();
  var sizeScratch = new Cartesian2();
  var postProcessMatrix4Scratch = new Matrix4();

  function updateSunPosition(postProcess, context, viewport) {
    var us = context.uniformState;
    var sunPosition = us.sunPositionWC;
    var viewMatrix = us.view;
    var viewProjectionMatrix = us.viewProjection;
    var projectionMatrix = us.projection;

    // create up sampled render state
    var viewportTransformation = Matrix4.computeViewportTransformation(
      viewport,
      0.0,
      1.0,
      postProcessMatrix4Scratch
    );
    var sunPositionEC = Matrix4.multiplyByPoint(
      viewMatrix,
      sunPosition,
      sunPositionECScratch
    );
    var sunPositionWC = Transforms.pointToGLWindowCoordinates(
      viewProjectionMatrix,
      viewportTransformation,
      sunPosition,
      sunPositionWCScratch
    );

    sunPositionEC.x += CesiumMath.SOLAR_RADIUS;
    var limbWC = Transforms.pointToGLWindowCoordinates(
      projectionMatrix,
      viewportTransformation,
      sunPositionEC,
      sunPositionEC
    );
    var sunSize =
      Cartesian2.magnitude(Cartesian2.subtract(limbWC, sunPositionWC, limbWC)) *
      30.0 *
      2.0;

    var size = sizeScratch;
    size.x = sunSize;
    size.y = sunSize;

    postProcess._uCenter = Cartesian2.clone(sunPositionWC, postProcess._uCenter);
    postProcess._uRadius = Math.max(size.x, size.y) * 0.15;

    var width = context.drawingBufferWidth;
    var height = context.drawingBufferHeight;

    var stages = postProcess._stages;
    var firstStage = stages.get(0);

    var downSampleWidth = firstStage.outputTexture.width;
    var downSampleHeight = firstStage.outputTexture.height;

    var downSampleViewport = new BoundingRectangle();
    downSampleViewport.width = downSampleWidth;
    downSampleViewport.height = downSampleHeight;

    // create down sampled render state
    viewportTransformation = Matrix4.computeViewportTransformation(
      downSampleViewport,
      0.0,
      1.0,
      postProcessMatrix4Scratch
    );
    sunPositionWC = Transforms.pointToGLWindowCoordinates(
      viewProjectionMatrix,
      viewportTransformation,
      sunPosition,
      sunPositionWCScratch
    );

    size.x *= downSampleWidth / width;
    size.y *= downSampleHeight / height;

    var scissorRectangle = firstStage.scissorRectangle;
    scissorRectangle.x = Math.max(sunPositionWC.x - size.x * 0.5, 0.0);
    scissorRectangle.y = Math.max(sunPositionWC.y - size.y * 0.5, 0.0);
    scissorRectangle.width = Math.min(size.x, width);
    scissorRectangle.height = Math.min(size.y, height);

    for (var i = 1; i < 4; ++i) {
      BoundingRectangle.clone(scissorRectangle, stages.get(i).scissorRectangle);
    }
  }

  SunPostProcess.prototype.clear = function (context, passState, clearColor) {
    this._sceneFramebuffer.clear(context, passState, clearColor);
    this._textureCache.clear(context);
  };

  SunPostProcess.prototype.update = function (passState) {
    var context = passState.context;
    var viewport = passState.viewport;

    var sceneFramebuffer = this._sceneFramebuffer;
    sceneFramebuffer.update(context, viewport);
    var framebuffer = sceneFramebuffer.getFramebuffer();

    this._textureCache.update(context);
    this._stages.update(context, false);

    updateSunPosition(this, context, viewport);

    return framebuffer;
  };

  SunPostProcess.prototype.execute = function (context) {
    var colorTexture = this._sceneFramebuffer.getFramebuffer().getColorTexture(0);
    var stages = this._stages;
    var length = stages.length;
    stages.get(0).execute(context, colorTexture);
    for (var i = 1; i < length; ++i) {
      stages.get(i).execute(context, stages.get(i - 1).outputTexture);
    }
  };

  SunPostProcess.prototype.copy = function (context, framebuffer) {
    if (!defined(this._copyColorCommand)) {
      var that = this;
      this._copyColorCommand = context.createViewportQuadCommand(PassThrough, {
        uniformMap: {
          colorTexture: function () {
            return that._stages.get(that._stages.length - 1).outputTexture;
          },
        },
        owner: this,
      });
    }

    this._copyColorCommand.framebuffer = framebuffer;
    this._copyColorCommand.execute(context);
  };

  SunPostProcess.prototype.isDestroyed = function () {
    return false;
  };

  SunPostProcess.prototype.destroy = function () {
    this._textureCache.destroy();
    this._stages.destroy();
    return destroyObject(this);
  };

  var requestRenderAfterFrame = function (scene) {
    return function () {
      scene.frameState.afterRender.push(function () {
        scene.requestRender();
      });
    };
  };

  /**
   * The container for all 3D graphical objects and state in a Cesium virtual scene.  Generally,
   * a scene is not created directly; instead, it is implicitly created by {@link CesiumWidget}.
   * <p>
   * <em><code>contextOptions</code> parameter details:</em>
   * </p>
   * <p>
   * The default values are:
   * <code>
   * {
   *   webgl : {
   *     alpha : false,
   *     depth : true,
   *     stencil : false,
   *     antialias : true,
   *     powerPreference: 'high-performance',
   *     premultipliedAlpha : true,
   *     preserveDrawingBuffer : false,
   *     failIfMajorPerformanceCaveat : false
   *   },
   *   allowTextureFilterAnisotropic : true
   * }
   * </code>
   * </p>
   * <p>
   * The <code>webgl</code> property corresponds to the {@link http://www.khronos.org/registry/webgl/specs/latest/#5.2|WebGLContextAttributes}
   * object used to create the WebGL context.
   * </p>
   * <p>
   * <code>webgl.alpha</code> defaults to false, which can improve performance compared to the standard WebGL default
   * of true.  If an application needs to composite Cesium above other HTML elements using alpha-blending, set
   * <code>webgl.alpha</code> to true.
   * </p>
   * <p>
   * The other <code>webgl</code> properties match the WebGL defaults for {@link http://www.khronos.org/registry/webgl/specs/latest/#5.2|WebGLContextAttributes}.
   * </p>
   * <p>
   * <code>allowTextureFilterAnisotropic</code> defaults to true, which enables anisotropic texture filtering when the
   * WebGL extension is supported.  Setting this to false will improve performance, but hurt visual quality, especially for horizon views.
   * </p>
   *
   * @alias Scene
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {HTMLCanvasElement} options.canvas The HTML canvas element to create the scene for.
   * @param {Object} [options.contextOptions] Context and WebGL creation properties.  See details above.
   * @param {Element} [options.creditContainer] The HTML element in which the credits will be displayed.
   * @param {Element} [options.creditViewport] The HTML element in which to display the credit popup.  If not specified, the viewport will be a added as a sibling of the canvas.
   * @param {MapProjection} [options.mapProjection=new GeographicProjection()] The map projection to use in 2D and Columbus View modes.
   * @param {Boolean} [options.orderIndependentTranslucency=true] If true and the configuration supports it, use order independent translucency.
   * @param {Boolean} [options.scene3DOnly=false] If true, optimizes memory use and performance for 3D mode but disables the ability to use 2D or Columbus View.
   * @param {Number} [options.terrainExaggeration=1.0] A scalar used to exaggerate the terrain. Note that terrain exaggeration will not modify any other primitive as they are positioned relative to the ellipsoid.
   * @param {Boolean} [options.shadows=false] Determines if shadows are cast by light sources.
   * @param {MapMode2D} [options.mapMode2D=MapMode2D.INFINITE_SCROLL] Determines if the 2D map is rotatable or can be scrolled infinitely in the horizontal direction.
   * @param {Boolean} [options.requestRenderMode=false] If true, rendering a frame will only occur when needed as determined by changes within the scene. Enabling improves performance of the application, but requires using {@link Scene#requestRender} to render a new frame explicitly in this mode. This will be necessary in many cases after making changes to the scene in other parts of the API. See {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}.
   * @param {Number} [options.maximumRenderTimeChange=0.0] If requestRenderMode is true, this value defines the maximum change in simulation time allowed before a render is requested. See {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}.
   *
   * @see CesiumWidget
   * @see {@link http://www.khronos.org/registry/webgl/specs/latest/#5.2|WebGLContextAttributes}
   *
   * @exception {DeveloperError} options and options.canvas are required.
   *
   * @example
   * // Create scene without anisotropic texture filtering
   * var scene = new Cesium.Scene({
   *   canvas : canvas,
   *   contextOptions : {
   *     allowTextureFilterAnisotropic : false
   *   }
   * });
   */
  function Scene(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var canvas = options.canvas;
    var creditContainer = options.creditContainer;
    var creditViewport = options.creditViewport;

    var contextOptions = clone(options.contextOptions);
    if (!defined(contextOptions)) {
      contextOptions = {};
    }
    if (!defined(contextOptions.webgl)) {
      contextOptions.webgl = {};
    }
    contextOptions.webgl.powerPreference = defaultValue(
      contextOptions.webgl.powerPreference,
      "high-performance"
    );

    //>>includeStart('debug', pragmas.debug);
    if (!defined(canvas)) {
      throw new DeveloperError("options and options.canvas are required.");
    }
    //>>includeEnd('debug');
    var hasCreditContainer = defined(creditContainer);
    var context = new Context(canvas, contextOptions);
    if (!hasCreditContainer) {
      creditContainer = document.createElement("div");
      creditContainer.style.position = "absolute";
      creditContainer.style.bottom = "0";
      creditContainer.style["text-shadow"] = "0 0 2px #000000";
      creditContainer.style.color = "#ffffff";
      creditContainer.style["font-size"] = "10px";
      creditContainer.style["padding-right"] = "5px";
      canvas.parentNode.appendChild(creditContainer);
    }
    if (!defined(creditViewport)) {
      creditViewport = canvas.parentNode;
    }

    this._id = createGuid();
    this._jobScheduler = new JobScheduler();
    this._frameState = new FrameState(
      context,
      new CreditDisplay(creditContainer, " • ", creditViewport),
      this._jobScheduler
    );
    this._frameState.scene3DOnly = defaultValue(options.scene3DOnly, false);
    this._removeCreditContainer = !hasCreditContainer;
    this._creditContainer = creditContainer;

    this._canvas = canvas;
    this._context = context;
    this._computeEngine = new ComputeEngine(context);
    this._globe = undefined;
    this._globeTranslucencyState = new GlobeTranslucencyState();
    this._primitives = new PrimitiveCollection();
    this._groundPrimitives = new PrimitiveCollection();

    this._globeHeight = undefined;
    this._cameraUnderground = false;

    this._logDepthBuffer = context.fragmentDepth;
    this._logDepthBufferDirty = true;

    this._tweens = new TweenCollection();

    this._shaderFrameCount = 0;

    this._sunPostProcess = undefined;

    this._computeCommandList = [];
    this._overlayCommandList = [];

    this._useOIT = defaultValue(options.orderIndependentTranslucency, true);
    this._executeOITFunction = undefined;

    this._depthPlane = new DepthPlane();

    this._clearColorCommand = new ClearCommand({
      color: new Color(),
      stencil: 0,
      owner: this,
    });
    this._depthClearCommand = new ClearCommand({
      depth: 1.0,
      owner: this,
    });
    this._stencilClearCommand = new ClearCommand({
      stencil: 0,
    });
    this._classificationStencilClearCommand = new ClearCommand({
      stencil: 0,
      renderState: RenderState.fromCache({
        stencilMask: StencilConstants$1.CLASSIFICATION_MASK,
      }),
    });

    this._depthOnlyRenderStateCache = {};

    this._transitioner = new SceneTransitioner(this);

    this._preUpdate = new Event();
    this._postUpdate = new Event();

    this._renderError = new Event();
    this._preRender = new Event();
    this._postRender = new Event();

    this._minimumDisableDepthTestDistance = 0.0;
    this._debugInspector = new DebugInspector();

    /**
     * Exceptions occurring in <code>render</code> are always caught in order to raise the
     * <code>renderError</code> event.  If this property is true, the error is rethrown
     * after the event is raised.  If this property is false, the <code>render</code> function
     * returns normally after raising the event.
     *
     * @type {Boolean}
     * @default false
     */
    this.rethrowRenderErrors = false;

    /**
     * Determines whether or not to instantly complete the
     * scene transition animation on user input.
     *
     * @type {Boolean}
     * @default true
     */
    this.completeMorphOnUserInput = true;

    /**
     * The event fired at the beginning of a scene transition.
     * @type {Event}
     * @default Event()
     */
    this.morphStart = new Event();

    /**
     * The event fired at the completion of a scene transition.
     * @type {Event}
     * @default Event()
     */
    this.morphComplete = new Event();

    /**
     * The {@link SkyBox} used to draw the stars.
     *
     * @type {SkyBox}
     * @default undefined
     *
     * @see Scene#backgroundColor
     */
    this.skyBox = undefined;

    /**
     * The sky atmosphere drawn around the globe.
     *
     * @type {SkyAtmosphere}
     * @default undefined
     */
    this.skyAtmosphere = undefined;

    /**
     * The {@link Sun}.
     *
     * @type {Sun}
     * @default undefined
     */
    this.sun = undefined;

    /**
     * Uses a bloom filter on the sun when enabled.
     *
     * @type {Boolean}
     * @default true
     */
    this.sunBloom = true;
    this._sunBloom = undefined;

    /**
     * The {@link Moon}
     *
     * @type Moon
     * @default undefined
     */
    this.moon = undefined;

    /**
     * The background color, which is only visible if there is no sky box, i.e., {@link Scene#skyBox} is undefined.
     *
     * @type {Color}
     * @default {@link Color.BLACK}
     *
     * @see Scene#skyBox
     */
    this.backgroundColor = Color.clone(Color.BLACK);

    this._mode = SceneMode$1.SCENE3D;

    this._mapProjection = defined(options.mapProjection)
      ? options.mapProjection
      : new GeographicProjection();

    /**
     * The current morph transition time between 2D/Columbus View and 3D,
     * with 0.0 being 2D or Columbus View and 1.0 being 3D.
     *
     * @type {Number}
     * @default 1.0
     */
    this.morphTime = 1.0;

    /**
     * The far-to-near ratio of the multi-frustum when using a normal depth buffer.
     * <p>
     * This value is used to create the near and far values for each frustum of the multi-frustum. It is only used
     * when {@link Scene#logarithmicDepthBuffer} is <code>false</code>. When <code>logarithmicDepthBuffer</code> is
     * <code>true</code>, use {@link Scene#logarithmicDepthFarToNearRatio}.
     * </p>
     *
     * @type {Number}
     * @default 1000.0
     */
    this.farToNearRatio = 1000.0;

    /**
     * The far-to-near ratio of the multi-frustum when using a logarithmic depth buffer.
     * <p>
     * This value is used to create the near and far values for each frustum of the multi-frustum. It is only used
     * when {@link Scene#logarithmicDepthBuffer} is <code>true</code>. When <code>logarithmicDepthBuffer</code> is
     * <code>false</code>, use {@link Scene#farToNearRatio}.
     * </p>
     *
     * @type {Number}
     * @default 1e9
     */
    this.logarithmicDepthFarToNearRatio = 1e9;

    /**
     * Determines the uniform depth size in meters of each frustum of the multifrustum in 2D. If a primitive or model close
     * to the surface shows z-fighting, decreasing this will eliminate the artifact, but decrease performance. On the
     * other hand, increasing this will increase performance but may cause z-fighting among primitives close to the surface.
     *
     * @type {Number}
     * @default 1.75e6
     */
    this.nearToFarDistance2D = 1.75e6;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * A function that determines what commands are executed.  As shown in the examples below,
     * the function receives the command's <code>owner</code> as an argument, and returns a boolean indicating if the
     * command should be executed.
     * </p>
     * <p>
     * The default is <code>undefined</code>, indicating that all commands are executed.
     * </p>
     *
     * @type Function
     *
     * @default undefined
     *
     * @example
     * // Do not execute any commands.
     * scene.debugCommandFilter = function(command) {
     *     return false;
     * };
     *
     * // Execute only the billboard's commands.  That is, only draw the billboard.
     * var billboards = new Cesium.BillboardCollection();
     * scene.debugCommandFilter = function(command) {
     *     return command.owner === billboards;
     * };
     */
    this.debugCommandFilter = undefined;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * When <code>true</code>, commands are randomly shaded.  This is useful
     * for performance analysis to see what parts of a scene or model are
     * command-dense and could benefit from batching.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.debugShowCommands = false;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * When <code>true</code>, commands are shaded based on the frustums they
     * overlap.  Commands in the closest frustum are tinted red, commands in
     * the next closest are green, and commands in the farthest frustum are
     * blue.  If a command overlaps more than one frustum, the color components
     * are combined, e.g., a command overlapping the first two frustums is tinted
     * yellow.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.debugShowFrustums = false;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * Displays frames per second and time between frames.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.debugShowFramesPerSecond = false;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * Displays depth information for the indicated frustum.
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.debugShowGlobeDepth = false;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * Indicates which frustum will have depth information displayed.
     * </p>
     *
     * @type Number
     *
     * @default 1
     */
    this.debugShowDepthFrustum = 1;

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * When <code>true</code>, draws outlines to show the boundaries of the camera frustums
     * </p>
     *
     * @type Boolean
     *
     * @default false
     */
    this.debugShowFrustumPlanes = false;
    this._debugShowFrustumPlanes = false;
    this._debugFrustumPlanes = undefined;

    /**
     * When <code>true</code>, enables picking using the depth buffer.
     *
     * @type Boolean
     * @default true
     */
    this.useDepthPicking = true;

    /**
     * When <code>true</code>, enables picking translucent geometry using the depth buffer. Note that {@link Scene#useDepthPicking} must also be true for enabling this to work.
     *
     * <p>
     * Render must be called between picks.
     * <br>There is a decrease in performance when enabled. There are extra draw calls to write depth for
     * translucent geometry.
     * </p>
     *
     * @example
     * // picking the position of a translucent primitive
     * viewer.screenSpaceEventHandler.setInputAction(function onLeftClick(movement) {
     *      var pickedFeature = viewer.scene.pick(movement.position);
     *      if (!Cesium.defined(pickedFeature)) {
     *          // nothing picked
     *          return;
     *      }
     *      viewer.scene.render();
     *      var worldPosition = viewer.scene.pickPosition(movement.position);
     * }, Cesium.ScreenSpaceEventType.LEFT_CLICK);
     *
     * @type {Boolean}
     * @default false
     */
    this.pickTranslucentDepth = false;

    /**
     * The time in milliseconds to wait before checking if the camera has not moved and fire the cameraMoveEnd event.
     * @type {Number}
     * @default 500.0
     * @private
     */
    this.cameraEventWaitTime = 500.0;

    /**
     * Blends the atmosphere to geometry far from the camera for horizon views. Allows for additional
     * performance improvements by rendering less geometry and dispatching less terrain requests.
     * @type {Fog}
     */
    this.fog = new Fog();

    this._shadowMapCamera = new Camera(this);

    /**
     * The shadow map for the scene's light source. When enabled, models, primitives, and the globe may cast and receive shadows.
     * @type {ShadowMap}
     */
    this.shadowMap = new ShadowMap({
      context: context,
      lightCamera: this._shadowMapCamera,
      enabled: defaultValue(options.shadows, false),
    });

    /**
     * When <code>false</code>, 3D Tiles will render normally. When <code>true</code>, classified 3D Tile geometry will render normally and
     * unclassified 3D Tile geometry will render with the color multiplied by {@link Scene#invertClassificationColor}.
     * @type {Boolean}
     * @default false
     */
    this.invertClassification = false;

    /**
     * The highlight color of unclassified 3D Tile geometry when {@link Scene#invertClassification} is <code>true</code>.
     * <p>When the color's alpha is less than 1.0, the unclassified portions of the 3D Tiles will not blend correctly with the classified positions of the 3D Tiles.</p>
     * <p>Also, when the color's alpha is less than 1.0, the WEBGL_depth_texture and EXT_frag_depth WebGL extensions must be supported.</p>
     * @type {Color}
     * @default Color.WHITE
     */
    this.invertClassificationColor = Color.clone(Color.WHITE);

    this._actualInvertClassificationColor = Color.clone(
      this._invertClassificationColor
    );
    this._invertClassification = new InvertClassification();

    /**
     * The focal length for use when with cardboard or WebVR.
     * @type {Number}
     */
    this.focalLength = undefined;

    /**
     * The eye separation distance in meters for use with cardboard or WebVR.
     * @type {Number}
     */
    this.eyeSeparation = undefined;

    /**
     * Post processing effects applied to the final render.
     * @type {PostProcessStageCollection}
     */
    this.postProcessStages = new PostProcessStageCollection();

    this._brdfLutGenerator = new BrdfLutGenerator();

    this._terrainExaggeration = defaultValue(options.terrainExaggeration, 1.0);

    this._performanceDisplay = undefined;
    this._debugVolume = undefined;

    this._screenSpaceCameraController = new ScreenSpaceCameraController(this);
    this._cameraUnderground = false;
    this._mapMode2D = defaultValue(options.mapMode2D, MapMode2D$1.INFINITE_SCROLL);

    // Keeps track of the state of a frame. FrameState is the state across
    // the primitives of the scene. This state is for internally keeping track
    // of celestial and environment effects that need to be updated/rendered in
    // a certain order as well as updating/tracking framebuffer usage.
    this._environmentState = {
      skyBoxCommand: undefined,
      skyAtmosphereCommand: undefined,
      sunDrawCommand: undefined,
      sunComputeCommand: undefined,
      moonCommand: undefined,

      isSunVisible: false,
      isMoonVisible: false,
      isReadyForAtmosphere: false,
      isSkyAtmosphereVisible: false,

      clearGlobeDepth: false,
      useDepthPlane: false,
      renderTranslucentDepthForPick: false,

      originalFramebuffer: undefined,
      useGlobeDepthFramebuffer: false,
      separatePrimitiveFramebuffer: false,
      useOIT: false,
      useInvertClassification: false,
      usePostProcess: false,
      usePostProcessSelected: false,
      useWebVR: false,
    };

    this._useWebVR = false;
    this._cameraVR = undefined;
    this._aspectRatioVR = undefined;

    /**
     * When <code>true</code>, rendering a frame will only occur when needed as determined by changes within the scene.
     * Enabling improves performance of the application, but requires using {@link Scene#requestRender}
     * to render a new frame explicitly in this mode. This will be necessary in many cases after making changes
     * to the scene in other parts of the API.
     *
     * @see {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}
     * @see Scene#maximumRenderTimeChange
     * @see Scene#requestRender
     *
     * @type {Boolean}
     * @default false
     */
    this.requestRenderMode = defaultValue(options.requestRenderMode, false);
    this._renderRequested = true;

    /**
     * If {@link Scene#requestRenderMode} is <code>true</code>, this value defines the maximum change in
     * simulation time allowed before a render is requested. Lower values increase the number of frames rendered
     * and higher values decrease the number of frames rendered. If <code>undefined</code>, changes to
     * the simulation time will never request a render.
     * This value impacts the rate of rendering for changes in the scene like lighting, entity property updates,
     * and animations.
     *
     * @see {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}
     * @see Scene#requestRenderMode
     *
     * @type {Number}
     * @default 0.0
     */
    this.maximumRenderTimeChange = defaultValue(
      options.maximumRenderTimeChange,
      0.0
    );
    this._lastRenderTime = undefined;
    this._frameRateMonitor = undefined;

    this._removeRequestListenerCallback = RequestScheduler.requestCompletedEvent.addEventListener(
      requestRenderAfterFrame(this)
    );
    this._removeTaskProcessorListenerCallback = TaskProcessor.taskCompletedEvent.addEventListener(
      requestRenderAfterFrame(this)
    );
    this._removeGlobeCallbacks = [];

    var viewport = new BoundingRectangle(
      0,
      0,
      context.drawingBufferWidth,
      context.drawingBufferHeight
    );
    var camera = new Camera(this);

    if (this._logDepthBuffer) {
      camera.frustum.near = 0.1;
      camera.frustum.far = 10000000000.0;
    }

    /**
     * The camera view for the scene camera flight destination. Used for preloading flight destination tiles.
     * @type {Camera}
     * @private
     */
    this.preloadFlightCamera = new Camera(this);

    /**
     * The culling volume for the scene camera flight destination. Used for preloading flight destination tiles.
     * @type {CullingVolume}
     * @private
     */
    this.preloadFlightCullingVolume = undefined;

    this._picking = new Picking(this);
    this._defaultView = new View(this, camera, viewport);
    this._view = this._defaultView;

    this._hdr = undefined;
    this._hdrDirty = undefined;
    this.highDynamicRange = false;
    this.gamma = 2.2;

    /**
     * The spherical harmonic coefficients for image-based lighting of PBR models.
     * @type {Cartesian3[]}
     */
    this.sphericalHarmonicCoefficients = undefined;

    /**
     * The url to the KTX file containing the specular environment map and convoluted mipmaps for image-based lighting of PBR models.
     * @type {String}
     */
    this.specularEnvironmentMaps = undefined;
    this._specularEnvironmentMapAtlas = undefined;

    /**
     * The light source for shading. Defaults to a directional light from the Sun.
     * @type {Light}
     */
    this.light = new SunLight();

    // Give frameState, camera, and screen space camera controller initial state before rendering
    updateFrameNumber(this, 0.0, JulianDate.now());
    this.updateFrameState();
    this.initializeFrame();
  }

  function updateGlobeListeners(scene, globe) {
    for (var i = 0; i < scene._removeGlobeCallbacks.length; ++i) {
      scene._removeGlobeCallbacks[i]();
    }
    scene._removeGlobeCallbacks.length = 0;

    var removeGlobeCallbacks = [];
    if (defined(globe)) {
      removeGlobeCallbacks.push(
        globe.imageryLayersUpdatedEvent.addEventListener(
          requestRenderAfterFrame(scene)
        )
      );
      removeGlobeCallbacks.push(
        globe.terrainProviderChanged.addEventListener(
          requestRenderAfterFrame(scene)
        )
      );
    }
    scene._removeGlobeCallbacks = removeGlobeCallbacks;
  }

  Object.defineProperties(Scene.prototype, {
    /**
     * Gets the canvas element to which this scene is bound.
     * @memberof Scene.prototype
     *
     * @type {HTMLCanvasElement}
     * @readonly
     */
    canvas: {
      get: function () {
        return this._canvas;
      },
    },

    /**
     * The drawingBufferHeight of the underlying GL context.
     * @memberof Scene.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @see {@link https://www.khronos.org/registry/webgl/specs/1.0/#DOM-WebGLRenderingContext-drawingBufferHeight|drawingBufferHeight}
     */
    drawingBufferHeight: {
      get: function () {
        return this._context.drawingBufferHeight;
      },
    },

    /**
     * The drawingBufferHeight of the underlying GL context.
     * @memberof Scene.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @see {@link https://www.khronos.org/registry/webgl/specs/1.0/#DOM-WebGLRenderingContext-drawingBufferHeight|drawingBufferHeight}
     */
    drawingBufferWidth: {
      get: function () {
        return this._context.drawingBufferWidth;
      },
    },

    /**
     * The maximum aliased line width, in pixels, supported by this WebGL implementation.  It will be at least one.
     * @memberof Scene.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>ALIASED_LINE_WIDTH_RANGE</code>.
     */
    maximumAliasedLineWidth: {
      get: function () {
        return ContextLimits.maximumAliasedLineWidth;
      },
    },

    /**
     * The maximum length in pixels of one edge of a cube map, supported by this WebGL implementation.  It will be at least 16.
     * @memberof Scene.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @see {@link https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGet.xml|glGet} with <code>GL_MAX_CUBE_MAP_TEXTURE_SIZE</code>.
     */
    maximumCubeMapSize: {
      get: function () {
        return ContextLimits.maximumCubeMapSize;
      },
    },

    /**
     * Returns <code>true</code> if the {@link Scene#pickPosition} function is supported.
     * @memberof Scene.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @see Scene#pickPosition
     */
    pickPositionSupported: {
      get: function () {
        return this._context.depthTexture;
      },
    },

    /**
     * Returns <code>true</code> if the {@link Scene#sampleHeight} and {@link Scene#sampleHeightMostDetailed} functions are supported.
     * @memberof Scene.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @see Scene#sampleHeight
     * @see Scene#sampleHeightMostDetailed
     */
    sampleHeightSupported: {
      get: function () {
        return this._context.depthTexture;
      },
    },

    /**
     * Returns <code>true</code> if the {@link Scene#clampToHeight} and {@link Scene#clampToHeightMostDetailed} functions are supported.
     * @memberof Scene.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @see Scene#clampToHeight
     * @see Scene#clampToHeightMostDetailed
     */
    clampToHeightSupported: {
      get: function () {
        return this._context.depthTexture;
      },
    },

    /**
     * Returns <code>true</code> if the {@link Scene#invertClassification} is supported.
     * @memberof Scene.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @see Scene#invertClassification
     */
    invertClassificationSupported: {
      get: function () {
        return this._context.depthTexture;
      },
    },

    /**
     * Returns <code>true</code> if specular environment maps are supported.
     * @memberof Scene.prototype
     *
     * @type {Boolean}
     * @readonly
     *
     * @see Scene#specularEnvironmentMaps
     */
    specularEnvironmentMapsSupported: {
      get: function () {
        return OctahedralProjectedCubeMap.isSupported(this._context);
      },
    },

    /**
     * Gets or sets the depth-test ellipsoid.
     * @memberof Scene.prototype
     *
     * @type {Globe}
     */
    globe: {
      get: function () {
        return this._globe;
      },

      set: function (globe) {
        this._globe = this._globe && this._globe.destroy();
        this._globe = globe;

        updateGlobeListeners(this, globe);
      },
    },

    /**
     * Gets the collection of primitives.
     * @memberof Scene.prototype
     *
     * @type {PrimitiveCollection}
     * @readonly
     */
    primitives: {
      get: function () {
        return this._primitives;
      },
    },

    /**
     * Gets the collection of ground primitives.
     * @memberof Scene.prototype
     *
     * @type {PrimitiveCollection}
     * @readonly
     */
    groundPrimitives: {
      get: function () {
        return this._groundPrimitives;
      },
    },

    /**
     * Gets or sets the camera.
     * @memberof Scene.prototype
     *
     * @type {Camera}
     * @readonly
     */
    camera: {
      get: function () {
        return this._view.camera;
      },
      set: function (camera) {
        // For internal use only. Documentation is still @readonly.
        this._view.camera = camera;
      },
    },

    /**
     * Gets or sets the view.
     * @memberof Scene.prototype
     *
     * @type {View}
     * @readonly
     *
     * @private
     */
    view: {
      get: function () {
        return this._view;
      },
      set: function (view) {
        // For internal use only. Documentation is still @readonly.
        this._view = view;
      },
    },

    /**
     * Gets the default view.
     * @memberof Scene.prototype
     *
     * @type {View}
     * @readonly
     *
     * @private
     */
    defaultView: {
      get: function () {
        return this._defaultView;
      },
    },

    /**
     * Gets picking functions and state
     * @memberof Scene.prototype
     *
     * @type {Picking}
     * @readonly
     *
     * @private
     */
    picking: {
      get: function () {
        return this._picking;
      },
    },

    /**
     * Gets the controller for camera input handling.
     * @memberof Scene.prototype
     *
     * @type {ScreenSpaceCameraController}
     * @readonly
     */
    screenSpaceCameraController: {
      get: function () {
        return this._screenSpaceCameraController;
      },
    },

    /**
     * Get the map projection to use in 2D and Columbus View modes.
     * @memberof Scene.prototype
     *
     * @type {MapProjection}
     * @readonly
     *
     * @default new GeographicProjection()
     */
    mapProjection: {
      get: function () {
        return this._mapProjection;
      },
    },

    /**
     * Gets the job scheduler
     * @memberof Scene.prototype
     * @type {JobScheduler}
     * @readonly
     *
     * @private
     */
    jobScheduler: {
      get: function () {
        return this._jobScheduler;
      },
    },

    /**
     * Gets state information about the current scene. If called outside of a primitive's <code>update</code>
     * function, the previous frame's state is returned.
     * @memberof Scene.prototype
     *
     * @type {FrameState}
     * @readonly
     *
     * @private
     */
    frameState: {
      get: function () {
        return this._frameState;
      },
    },

    /**
     * Gets the environment state.
     * @memberof Scene.prototype
     *
     * @type {EnvironmentState}
     * @readonly
     *
     * @private
     */
    environmentState: {
      get: function () {
        return this._environmentState;
      },
    },

    /**
     * Gets the collection of tweens taking place in the scene.
     * @memberof Scene.prototype
     *
     * @type {TweenCollection}
     * @readonly
     *
     * @private
     */
    tweens: {
      get: function () {
        return this._tweens;
      },
    },

    /**
     * Gets the collection of image layers that will be rendered on the globe.
     * @memberof Scene.prototype
     *
     * @type {ImageryLayerCollection}
     * @readonly
     */
    imageryLayers: {
      get: function () {
        if (!defined(this.globe)) {
          return undefined;
        }

        return this.globe.imageryLayers;
      },
    },

    /**
     * The terrain provider providing surface geometry for the globe.
     * @memberof Scene.prototype
     *
     * @type {TerrainProvider}
     */
    terrainProvider: {
      get: function () {
        if (!defined(this.globe)) {
          return undefined;
        }

        return this.globe.terrainProvider;
      },
      set: function (terrainProvider) {
        if (defined(this.globe)) {
          this.globe.terrainProvider = terrainProvider;
        }
      },
    },

    /**
     * Gets an event that's raised when the terrain provider is changed
     * @memberof Scene.prototype
     *
     * @type {Event}
     * @readonly
     */
    terrainProviderChanged: {
      get: function () {
        if (!defined(this.globe)) {
          return undefined;
        }

        return this.globe.terrainProviderChanged;
      },
    },

    /**
     * Gets the event that will be raised before the scene is updated or rendered.  Subscribers to the event
     * receive the Scene instance as the first parameter and the current time as the second parameter.
     * @memberof Scene.prototype
     *
     * @see {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}
     * @see Scene#postUpdate
     * @see Scene#preRender
     * @see Scene#postRender
     *
     * @type {Event}
     * @readonly
     */
    preUpdate: {
      get: function () {
        return this._preUpdate;
      },
    },

    /**
     * Gets the event that will be raised immediately after the scene is updated and before the scene is rendered.
     * Subscribers to the event receive the Scene instance as the first parameter and the current time as the second
     * parameter.
     * @memberof Scene.prototype
     *
     * @see {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}
     * @see Scene#preUpdate
     * @see Scene#preRender
     * @see Scene#postRender
     *
     * @type {Event}
     * @readonly
     */
    postUpdate: {
      get: function () {
        return this._postUpdate;
      },
    },

    /**
     * Gets the event that will be raised when an error is thrown inside the <code>render</code> function.
     * The Scene instance and the thrown error are the only two parameters passed to the event handler.
     * By default, errors are not rethrown after this event is raised, but that can be changed by setting
     * the <code>rethrowRenderErrors</code> property.
     * @memberof Scene.prototype
     *
     * @type {Event}
     * @readonly
     */
    renderError: {
      get: function () {
        return this._renderError;
      },
    },

    /**
     * Gets the event that will be raised after the scene is updated and immediately before the scene is rendered.
     * Subscribers to the event receive the Scene instance as the first parameter and the current time as the second
     * parameter.
     * @memberof Scene.prototype
     *
     * @see {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}
     * @see Scene#preUpdate
     * @see Scene#postUpdate
     * @see Scene#postRender
     *
     * @type {Event}
     * @readonly
     */
    preRender: {
      get: function () {
        return this._preRender;
      },
    },

    /**
     * Gets the event that will be raised immediately after the scene is rendered.  Subscribers to the event
     * receive the Scene instance as the first parameter and the current time as the second parameter.
     * @memberof Scene.prototype
     *
     * @see {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}
     * @see Scene#preUpdate
     * @see Scene#postUpdate
     * @see Scene#postRender
     *
     * @type {Event}
     * @readonly
     */
    postRender: {
      get: function () {
        return this._postRender;
      },
    },

    /**
     * Gets the simulation time when the scene was last rendered. Returns undefined if the scene has not yet been
     * rendered.
     * @memberof Scene.prototype
     *
     * @type {JulianDate}
     * @readonly
     */
    lastRenderTime: {
      get: function () {
        return this._lastRenderTime;
      },
    },

    /**
     * @memberof Scene.prototype
     * @private
     * @readonly
     */
    context: {
      get: function () {
        return this._context;
      },
    },

    /**
     * This property is for debugging only; it is not for production use.
     * <p>
     * When {@link Scene.debugShowFrustums} is <code>true</code>, this contains
     * properties with statistics about the number of command execute per frustum.
     * <code>totalCommands</code> is the total number of commands executed, ignoring
     * overlap. <code>commandsInFrustums</code> is an array with the number of times
     * commands are executed redundantly, e.g., how many commands overlap two or
     * three frustums.
     * </p>
     *
     * @memberof Scene.prototype
     *
     * @type {Object}
     * @readonly
     *
     * @default undefined
     */
    debugFrustumStatistics: {
      get: function () {
        return this._view.debugFrustumStatistics;
      },
    },

    /**
     * Gets whether or not the scene is optimized for 3D only viewing.
     * @memberof Scene.prototype
     * @type {Boolean}
     * @readonly
     */
    scene3DOnly: {
      get: function () {
        return this._frameState.scene3DOnly;
      },
    },

    /**
     * Gets whether or not the scene has order independent translucency enabled.
     * Note that this only reflects the original construction option, and there are
     * other factors that could prevent OIT from functioning on a given system configuration.
     * @memberof Scene.prototype
     * @type {Boolean}
     * @readonly
     */
    orderIndependentTranslucency: {
      get: function () {
        return this._useOIT;
      },
    },

    /**
     * Gets the unique identifier for this scene.
     * @memberof Scene.prototype
     * @type {String}
     * @readonly
     */
    id: {
      get: function () {
        return this._id;
      },
    },

    /**
     * Gets or sets the current mode of the scene.
     * @memberof Scene.prototype
     * @type {SceneMode}
     * @default {@link SceneMode.SCENE3D}
     */
    mode: {
      get: function () {
        return this._mode;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (this.scene3DOnly && value !== SceneMode$1.SCENE3D) {
          throw new DeveloperError(
            "Only SceneMode.SCENE3D is valid when scene3DOnly is true."
          );
        }
        //>>includeEnd('debug');
        if (value === SceneMode$1.SCENE2D) {
          this.morphTo2D(0);
        } else if (value === SceneMode$1.SCENE3D) {
          this.morphTo3D(0);
        } else if (value === SceneMode$1.COLUMBUS_VIEW) {
          this.morphToColumbusView(0);
          //>>includeStart('debug', pragmas.debug);
        } else {
          throw new DeveloperError(
            "value must be a valid SceneMode enumeration."
          );
          //>>includeEnd('debug');
        }
        this._mode = value;
      },
    },

    /**
     * Gets the number of frustums used in the last frame.
     * @memberof Scene.prototype
     * @type {FrustumCommands[]}
     *
     * @private
     */
    frustumCommandsList: {
      get: function () {
        return this._view.frustumCommandsList;
      },
    },

    /**
     * Gets the number of frustums used in the last frame.
     * @memberof Scene.prototype
     * @type {Number}
     *
     * @private
     */
    numberOfFrustums: {
      get: function () {
        return this._view.frustumCommandsList.length;
      },
    },

    /**
     * Gets the scalar used to exaggerate the terrain.
     * @memberof Scene.prototype
     * @type {Number}
     * @readonly
     */
    terrainExaggeration: {
      get: function () {
        return this._terrainExaggeration;
      },
    },

    /**
     * When <code>true</code>, splits the scene into two viewports with steroscopic views for the left and right eyes.
     * Used for cardboard and WebVR.
     * @memberof Scene.prototype
     * @type {Boolean}
     * @default false
     */
    useWebVR: {
      get: function () {
        return this._useWebVR;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (this.camera.frustum instanceof OrthographicFrustum) {
          throw new DeveloperError(
            "VR is unsupported with an orthographic projection."
          );
        }
        //>>includeEnd('debug');
        this._useWebVR = value;
        if (this._useWebVR) {
          this._frameState.creditDisplay.container.style.visibility = "hidden";
          this._cameraVR = new Camera(this);
          if (!defined(this._deviceOrientationCameraController)) {
            this._deviceOrientationCameraController = new DeviceOrientationCameraController(
              this
            );
          }

          this._aspectRatioVR = this.camera.frustum.aspectRatio;
        } else {
          this._frameState.creditDisplay.container.style.visibility = "visible";
          this._cameraVR = undefined;
          this._deviceOrientationCameraController =
            this._deviceOrientationCameraController &&
            !this._deviceOrientationCameraController.isDestroyed() &&
            this._deviceOrientationCameraController.destroy();

          this.camera.frustum.aspectRatio = this._aspectRatioVR;
          this.camera.frustum.xOffset = 0.0;
        }
      },
    },

    /**
     * Determines if the 2D map is rotatable or can be scrolled infinitely in the horizontal direction.
     * @memberof Scene.prototype
     * @type {MapMode2D}
     * @readonly
     */
    mapMode2D: {
      get: function () {
        return this._mapMode2D;
      },
    },

    /**
     * Gets or sets the position of the Imagery splitter within the viewport.  Valid values are between 0.0 and 1.0.
     * @memberof Scene.prototype
     *
     * @type {Number}
     */
    imagerySplitPosition: {
      get: function () {
        return this._frameState.imagerySplitPosition;
      },
      set: function (value) {
        this._frameState.imagerySplitPosition = value;
      },
    },

    /**
     * The distance from the camera at which to disable the depth test of billboards, labels and points
     * to, for example, prevent clipping against terrain. When set to zero, the depth test should always
     * be applied. When less than zero, the depth test should never be applied. Setting the disableDepthTestDistance
     * property of a billboard, label or point will override this value.
     * @memberof Scene.prototype
     * @type {Number}
     * @default 0.0
     */
    minimumDisableDepthTestDistance: {
      get: function () {
        return this._minimumDisableDepthTestDistance;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value) || value < 0.0) {
          throw new DeveloperError(
            "minimumDisableDepthTestDistance must be greater than or equal to 0.0."
          );
        }
        //>>includeEnd('debug');
        this._minimumDisableDepthTestDistance = value;
      },
    },

    /**
     * Whether or not to use a logarithmic depth buffer. Enabling this option will allow for less frustums in the multi-frustum,
     * increasing performance. This property relies on fragmentDepth being supported.
     * @memberof Scene.prototype
     * @type {Boolean}
     */
    logarithmicDepthBuffer: {
      get: function () {
        return this._logDepthBuffer;
      },
      set: function (value) {
        value = this._context.fragmentDepth && value;
        if (this._logDepthBuffer !== value) {
          this._logDepthBuffer = value;
          this._logDepthBufferDirty = true;
        }
      },
    },

    /**
     * The value used for gamma correction. This is only used when rendering with high dynamic range.
     * @memberof Scene.prototype
     * @type {Number}
     * @default 2.2
     */
    gamma: {
      get: function () {
        return this._context.uniformState.gamma;
      },
      set: function (value) {
        this._context.uniformState.gamma = value;
      },
    },

    /**
     * Whether or not to use high dynamic range rendering.
     * @memberof Scene.prototype
     * @type {Boolean}
     * @default true
     */
    highDynamicRange: {
      get: function () {
        return this._hdr;
      },
      set: function (value) {
        var context = this._context;
        var hdr =
          value &&
          context.depthTexture &&
          (context.colorBufferFloat || context.colorBufferHalfFloat);
        this._hdrDirty = hdr !== this._hdr;
        this._hdr = hdr;
      },
    },

    /**
     * Whether or not high dynamic range rendering is supported.
     * @memberof Scene.prototype
     * @type {Boolean}
     * @readonly
     * @default true
     */
    highDynamicRangeSupported: {
      get: function () {
        var context = this._context;
        return (
          context.depthTexture &&
          (context.colorBufferFloat || context.colorBufferHalfFloat)
        );
      },
    },

    /**
     * Whether or not the camera is underneath the globe.
     * @memberof Scene.prototype
     * @type {Boolean}
     * @readonly
     * @default false
     */
    cameraUnderground: {
      get: function () {
        return this._cameraUnderground;
      },
    },

    /**
     * Ratio between a pixel and a density-independent pixel. Provides a standard unit of
     * measure for real pixel measurements appropriate to a particular device.
     *
     * @memberof Scene.prototype
     * @type {Number}
     * @default 1.0
     * @private
     */
    pixelRatio: {
      get: function () {
        return this._frameState.pixelRatio;
      },
      set: function (value) {
        this._frameState.pixelRatio = value;
      },
    },

    /**
     * @private
     */
    opaqueFrustumNearOffset: {
      get: function () {
        return 0.9999;
      },
    },

    /**
     * @private
     */
    globeHeight: {
      get: function () {
        return this._globeHeight;
      },
    },
  });

  /**
   * Determines if a compressed texture format is supported.
   * @param {String} format The texture format. May be the name of the format or the WebGL extension name, e.g. s3tc or WEBGL_compressed_texture_s3tc.
   * @return {boolean} Whether or not the format is supported.
   */
  Scene.prototype.getCompressedTextureFormatSupported = function (format) {
    var context = this.context;
    return (
      ((format === "WEBGL_compressed_texture_s3tc" || format === "s3tc") &&
        context.s3tc) ||
      ((format === "WEBGL_compressed_texture_pvrtc" || format === "pvrtc") &&
        context.pvrtc) ||
      ((format === "WEBGL_compressed_texture_etc1" || format === "etc1") &&
        context.etc1)
    );
  };

  function updateDerivedCommands$1(scene, command, shadowsDirty) {
    var frameState = scene._frameState;
    var context = scene._context;
    var oit = scene._view.oit;
    var lightShadowMaps = frameState.shadowState.lightShadowMaps;
    var lightShadowsEnabled = frameState.shadowState.lightShadowsEnabled;

    var derivedCommands = command.derivedCommands;

    if (defined(command.pickId)) {
      derivedCommands.picking = DerivedCommand.createPickDerivedCommand(
        scene,
        command,
        context,
        derivedCommands.picking
      );
    }

    if (!command.pickOnly) {
      derivedCommands.depth = DerivedCommand.createDepthOnlyDerivedCommand(
        scene,
        command,
        context,
        derivedCommands.depth
      );
    }

    derivedCommands.originalCommand = command;

    if (scene._hdr) {
      derivedCommands.hdr = DerivedCommand.createHdrCommand(
        command,
        context,
        derivedCommands.hdr
      );
      command = derivedCommands.hdr.command;
      derivedCommands = command.derivedCommands;
    }

    if (lightShadowsEnabled && command.receiveShadows) {
      derivedCommands.shadows = ShadowMap.createReceiveDerivedCommand(
        lightShadowMaps,
        command,
        shadowsDirty,
        context,
        derivedCommands.shadows
      );
    }

    if (command.pass === Pass$1.TRANSLUCENT && defined(oit) && oit.isSupported()) {
      if (lightShadowsEnabled && command.receiveShadows) {
        derivedCommands.oit = defined(derivedCommands.oit)
          ? derivedCommands.oit
          : {};
        derivedCommands.oit.shadows = oit.createDerivedCommands(
          derivedCommands.shadows.receiveCommand,
          context,
          derivedCommands.oit.shadows
        );
      } else {
        derivedCommands.oit = oit.createDerivedCommands(
          command,
          context,
          derivedCommands.oit
        );
      }
    }
  }

  /**
   * @private
   */
  Scene.prototype.updateDerivedCommands = function (command) {
    if (!defined(command.derivedCommands)) {
      // Is not a DrawCommand
      return;
    }

    var frameState = this._frameState;
    var context = this._context;

    // Update derived commands when any shadow maps become dirty
    var shadowsDirty = false;
    var lastDirtyTime = frameState.shadowState.lastDirtyTime;
    if (command.lastDirtyTime !== lastDirtyTime) {
      command.lastDirtyTime = lastDirtyTime;
      command.dirty = true;
      shadowsDirty = true;
    }

    var useLogDepth = frameState.useLogDepth;
    var useHdr = this._hdr;
    var derivedCommands = command.derivedCommands;
    var hasLogDepthDerivedCommands = defined(derivedCommands.logDepth);
    var hasHdrCommands = defined(derivedCommands.hdr);
    var hasDerivedCommands = defined(derivedCommands.originalCommand);
    var needsLogDepthDerivedCommands = useLogDepth && !hasLogDepthDerivedCommands;
    var needsHdrCommands = useHdr && !hasHdrCommands;
    var needsDerivedCommands = (!useLogDepth || !useHdr) && !hasDerivedCommands;
    command.dirty =
      command.dirty ||
      needsLogDepthDerivedCommands ||
      needsHdrCommands ||
      needsDerivedCommands;

    if (command.dirty) {
      command.dirty = false;

      var shadowMaps = frameState.shadowState.shadowMaps;
      var shadowsEnabled = frameState.shadowState.shadowsEnabled;
      if (shadowsEnabled && command.castShadows) {
        derivedCommands.shadows = ShadowMap.createCastDerivedCommand(
          shadowMaps,
          command,
          shadowsDirty,
          context,
          derivedCommands.shadows
        );
      }

      if (hasLogDepthDerivedCommands || needsLogDepthDerivedCommands) {
        derivedCommands.logDepth = DerivedCommand.createLogDepthCommand(
          command,
          context,
          derivedCommands.logDepth
        );
        updateDerivedCommands$1(
          this,
          derivedCommands.logDepth.command,
          shadowsDirty
        );
      }
      if (hasDerivedCommands || needsDerivedCommands) {
        updateDerivedCommands$1(this, command, shadowsDirty);
      }
    }
  };

  var renderTilesetPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.RENDER,
  });

  var preloadTilesetPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.PRELOAD,
  });

  var preloadFlightTilesetPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.PRELOAD_FLIGHT,
  });

  var requestRenderModeDeferCheckPassState = new Cesium3DTilePassState({
    pass: Cesium3DTilePass$1.REQUEST_RENDER_MODE_DEFER_CHECK,
  });

  var scratchOccluderBoundingSphere = new BoundingSphere();
  var scratchOccluder;

  function getOccluder(scene) {
    // TODO: The occluder is the top-level globe. When we add
    //       support for multiple central bodies, this should be the closest one.
    var globe = scene.globe;
    if (
      scene._mode === SceneMode$1.SCENE3D &&
      defined(globe) &&
      globe.show &&
      !scene._cameraUnderground &&
      !scene._globeTranslucencyState.translucent
    ) {
      var ellipsoid = globe.ellipsoid;
      var minimumTerrainHeight = scene.frameState.minimumTerrainHeight;
      scratchOccluderBoundingSphere.radius =
        ellipsoid.minimumRadius + minimumTerrainHeight;
      scratchOccluder = Occluder.fromBoundingSphere(
        scratchOccluderBoundingSphere,
        scene.camera.positionWC,
        scratchOccluder
      );
      return scratchOccluder;
    }

    return undefined;
  }

  /**
   * @private
   */
  Scene.prototype.clearPasses = function (passes) {
    passes.render = false;
    passes.pick = false;
    passes.depth = false;
    passes.postProcess = false;
    passes.offscreen = false;
  };

  function updateFrameNumber(scene, frameNumber, time) {
    var frameState = scene._frameState;
    frameState.frameNumber = frameNumber;
    frameState.time = JulianDate.clone(time, frameState.time);
  }

  /**
   * @private
   */
  Scene.prototype.updateFrameState = function () {
    var camera = this.camera;

    var frameState = this._frameState;
    frameState.commandList.length = 0;
    frameState.shadowMaps.length = 0;
    frameState.brdfLutGenerator = this._brdfLutGenerator;
    frameState.environmentMap = this.skyBox && this.skyBox._cubeMap;
    frameState.mode = this._mode;
    frameState.morphTime = this.morphTime;
    frameState.mapProjection = this.mapProjection;
    frameState.camera = camera;
    frameState.cullingVolume = camera.frustum.computeCullingVolume(
      camera.positionWC,
      camera.directionWC,
      camera.upWC
    );
    frameState.occluder = getOccluder(this);
    frameState.terrainExaggeration = this._terrainExaggeration;
    frameState.minimumTerrainHeight = 0.0;
    frameState.minimumDisableDepthTestDistance = this._minimumDisableDepthTestDistance;
    frameState.invertClassification = this.invertClassification;
    frameState.useLogDepth =
      this._logDepthBuffer &&
      !(
        this.camera.frustum instanceof OrthographicFrustum ||
        this.camera.frustum instanceof OrthographicOffCenterFrustum
      );
    frameState.light = this.light;
    frameState.cameraUnderground = this._cameraUnderground;
    frameState.globeTranslucencyState = this._globeTranslucencyState;

    if (
      defined(this._specularEnvironmentMapAtlas) &&
      this._specularEnvironmentMapAtlas.ready
    ) {
      frameState.specularEnvironmentMaps = this._specularEnvironmentMapAtlas.texture;
      frameState.specularEnvironmentMapsMaximumLOD = this._specularEnvironmentMapAtlas.maximumMipmapLevel;
    } else {
      frameState.specularEnvironmentMaps = undefined;
      frameState.specularEnvironmentMapsMaximumLOD = undefined;
    }

    frameState.sphericalHarmonicCoefficients = this.sphericalHarmonicCoefficients;

    this._actualInvertClassificationColor = Color.clone(
      this.invertClassificationColor,
      this._actualInvertClassificationColor
    );
    if (!InvertClassification.isTranslucencySupported(this._context)) {
      this._actualInvertClassificationColor.alpha = 1.0;
    }

    frameState.invertClassificationColor = this._actualInvertClassificationColor;

    if (defined(this.globe)) {
      frameState.maximumScreenSpaceError = this.globe.maximumScreenSpaceError;
    } else {
      frameState.maximumScreenSpaceError = 2;
    }

    this.clearPasses(frameState.passes);

    frameState.tilesetPassState = undefined;
  };

  /**
   * @private
   */
  Scene.prototype.isVisible = function (command, cullingVolume, occluder) {
    return (
      defined(command) &&
      (!defined(command.boundingVolume) ||
        !command.cull ||
        (cullingVolume.computeVisibility(command.boundingVolume) !==
          Intersect$1.OUTSIDE &&
          (!defined(occluder) ||
            !command.occlude ||
            !command.boundingVolume.isOccluded(occluder))))
    );
  };

  var transformFrom2D = new Matrix4(
    0.0,
    0.0,
    1.0,
    0.0,
    1.0,
    0.0,
    0.0,
    0.0,
    0.0,
    1.0,
    0.0,
    0.0,
    0.0,
    0.0,
    0.0,
    1.0
  );
  transformFrom2D = Matrix4.inverseTransformation(
    transformFrom2D,
    transformFrom2D
  );

  function debugShowBoundingVolume(command, scene, passState, debugFramebuffer) {
    // Debug code to draw bounding volume for command.  Not optimized!
    // Assumes bounding volume is a bounding sphere or box
    var frameState = scene._frameState;
    var context = frameState.context;
    var boundingVolume = command.boundingVolume;

    if (defined(scene._debugVolume)) {
      scene._debugVolume.destroy();
    }

    var geometry;

    var center = Cartesian3.clone(boundingVolume.center);
    if (frameState.mode !== SceneMode$1.SCENE3D) {
      center = Matrix4.multiplyByPoint(transformFrom2D, center, center);
      var projection = frameState.mapProjection;
      var centerCartographic = projection.unproject(center);
      center = projection.ellipsoid.cartographicToCartesian(centerCartographic);
    }

    if (defined(boundingVolume.radius)) {
      var radius = boundingVolume.radius;

      geometry = GeometryPipeline.toWireframe(
        EllipsoidGeometry.createGeometry(
          new EllipsoidGeometry({
            radii: new Cartesian3(radius, radius, radius),
            vertexFormat: PerInstanceColorAppearance.FLAT_VERTEX_FORMAT,
          })
        )
      );

      scene._debugVolume = new Primitive({
        geometryInstances: new GeometryInstance({
          geometry: geometry,
          modelMatrix: Matrix4.fromTranslation(center),
          attributes: {
            color: new ColorGeometryInstanceAttribute(1.0, 0.0, 0.0, 1.0),
          },
        }),
        appearance: new PerInstanceColorAppearance({
          flat: true,
          translucent: false,
        }),
        asynchronous: false,
      });
    } else {
      var halfAxes = boundingVolume.halfAxes;

      geometry = GeometryPipeline.toWireframe(
        BoxGeometry.createGeometry(
          BoxGeometry.fromDimensions({
            dimensions: new Cartesian3(2.0, 2.0, 2.0),
            vertexFormat: PerInstanceColorAppearance.FLAT_VERTEX_FORMAT,
          })
        )
      );

      scene._debugVolume = new Primitive({
        geometryInstances: new GeometryInstance({
          geometry: geometry,
          modelMatrix: Matrix4.fromRotationTranslation(
            halfAxes,
            center,
            new Matrix4()
          ),
          attributes: {
            color: new ColorGeometryInstanceAttribute(1.0, 0.0, 0.0, 1.0),
          },
        }),
        appearance: new PerInstanceColorAppearance({
          flat: true,
          translucent: false,
        }),
        asynchronous: false,
      });
    }

    var savedCommandList = frameState.commandList;
    var commandList = (frameState.commandList = []);
    scene._debugVolume.update(frameState);

    command = commandList[0];

    if (frameState.useLogDepth) {
      var logDepth = DerivedCommand.createLogDepthCommand(command, context);
      command = logDepth.command;
    }

    var framebuffer;
    if (defined(debugFramebuffer)) {
      framebuffer = passState.framebuffer;
      passState.framebuffer = debugFramebuffer;
    }

    command.execute(context, passState);

    if (defined(framebuffer)) {
      passState.framebuffer = framebuffer;
    }

    frameState.commandList = savedCommandList;
  }

  function executeCommand(command, scene, context, passState, debugFramebuffer) {
    var frameState = scene._frameState;

    if (defined(scene.debugCommandFilter) && !scene.debugCommandFilter(command)) {
      return;
    }

    if (command instanceof ClearCommand) {
      command.execute(context, passState);
      return;
    }

    if (command.debugShowBoundingVolume && defined(command.boundingVolume)) {
      debugShowBoundingVolume(command, scene, passState, debugFramebuffer);
    }

    if (frameState.useLogDepth && defined(command.derivedCommands.logDepth)) {
      command = command.derivedCommands.logDepth.command;
    }

    var passes = frameState.passes;
    if (
      !passes.pick &&
      !passes.depth &&
      scene._hdr &&
      defined(command.derivedCommands) &&
      defined(command.derivedCommands.hdr)
    ) {
      command = command.derivedCommands.hdr.command;
    }

    if (passes.pick || passes.depth) {
      if (
        passes.pick &&
        !passes.depth &&
        defined(command.derivedCommands.picking)
      ) {
        command = command.derivedCommands.picking.pickCommand;
        command.execute(context, passState);
        return;
      } else if (defined(command.derivedCommands.depth)) {
        command = command.derivedCommands.depth.depthOnlyCommand;
        command.execute(context, passState);
        return;
      }
    }

    if (scene.debugShowCommands || scene.debugShowFrustums) {
      scene._debugInspector.executeDebugShowFrustumsCommand(
        scene,
        command,
        passState
      );
      return;
    }

    if (
      frameState.shadowState.lightShadowsEnabled &&
      command.receiveShadows &&
      defined(command.derivedCommands.shadows)
    ) {
      // If the command receives shadows, execute the derived shadows command.
      // Some commands, such as OIT derived commands, do not have derived shadow commands themselves
      // and instead shadowing is built-in. In this case execute the command regularly below.
      command.derivedCommands.shadows.receiveCommand.execute(context, passState);
    } else {
      command.execute(context, passState);
    }
  }

  function executeIdCommand(command, scene, context, passState) {
    var frameState = scene._frameState;
    var derivedCommands = command.derivedCommands;
    if (!defined(derivedCommands)) {
      return;
    }

    if (frameState.useLogDepth && defined(derivedCommands.logDepth)) {
      command = derivedCommands.logDepth.command;
    }

    derivedCommands = command.derivedCommands;
    if (defined(derivedCommands.picking)) {
      command = derivedCommands.picking.pickCommand;
      command.execute(context, passState);
    } else if (defined(derivedCommands.depth)) {
      command = derivedCommands.depth.depthOnlyCommand;
      command.execute(context, passState);
    }
  }

  function backToFront(a, b, position) {
    return (
      b.boundingVolume.distanceSquaredTo(position) -
      a.boundingVolume.distanceSquaredTo(position)
    );
  }

  function frontToBack(a, b, position) {
    // When distances are equal equal favor sorting b before a. This gives render priority to commands later in the list.
    return (
      a.boundingVolume.distanceSquaredTo(position) -
      b.boundingVolume.distanceSquaredTo(position) +
      CesiumMath.EPSILON12
    );
  }

  function executeTranslucentCommandsBackToFront(
    scene,
    executeFunction,
    passState,
    commands,
    invertClassification
  ) {
    var context = scene.context;

    mergeSort(commands, backToFront, scene.camera.positionWC);

    if (defined(invertClassification)) {
      executeFunction(
        invertClassification.unclassifiedCommand,
        scene,
        context,
        passState
      );
    }

    var length = commands.length;
    for (var i = 0; i < length; ++i) {
      executeFunction(commands[i], scene, context, passState);
    }
  }

  function executeTranslucentCommandsFrontToBack(
    scene,
    executeFunction,
    passState,
    commands,
    invertClassification
  ) {
    var context = scene.context;

    mergeSort(commands, frontToBack, scene.camera.positionWC);

    if (defined(invertClassification)) {
      executeFunction(
        invertClassification.unclassifiedCommand,
        scene,
        context,
        passState
      );
    }

    var length = commands.length;
    for (var i = 0; i < length; ++i) {
      executeFunction(commands[i], scene, context, passState);
    }
  }

  function getDebugGlobeDepth(scene, index) {
    var globeDepths = scene._view.debugGlobeDepths;
    var globeDepth = globeDepths[index];
    if (!defined(globeDepth) && scene.context.depthTexture) {
      globeDepth = new GlobeDepth();
      globeDepths[index] = globeDepth;
    }
    return globeDepth;
  }

  var scratchPerspectiveFrustum$1 = new PerspectiveFrustum();
  var scratchPerspectiveOffCenterFrustum$1 = new PerspectiveOffCenterFrustum();
  var scratchOrthographicFrustum$1 = new OrthographicFrustum();
  var scratchOrthographicOffCenterFrustum$1 = new OrthographicOffCenterFrustum();

  function executeCommands$1(scene, passState) {
    var camera = scene.camera;
    var context = scene.context;
    var frameState = scene.frameState;
    var us = context.uniformState;

    us.updateCamera(camera);

    // Create a working frustum from the original camera frustum.
    var frustum;
    if (defined(camera.frustum.fov)) {
      frustum = camera.frustum.clone(scratchPerspectiveFrustum$1);
    } else if (defined(camera.frustum.infiniteProjectionMatrix)) {
      frustum = camera.frustum.clone(scratchPerspectiveOffCenterFrustum$1);
    } else if (defined(camera.frustum.width)) {
      frustum = camera.frustum.clone(scratchOrthographicFrustum$1);
    } else {
      frustum = camera.frustum.clone(scratchOrthographicOffCenterFrustum$1);
    }

    // Ideally, we would render the sky box and atmosphere last for
    // early-z, but we would have to draw it in each frustum
    frustum.near = camera.frustum.near;
    frustum.far = camera.frustum.far;
    us.updateFrustum(frustum);
    us.updatePass(Pass$1.ENVIRONMENT);

    var passes = frameState.passes;
    var picking = passes.pick;
    var environmentState = scene._environmentState;
    var view = scene._view;
    var renderTranslucentDepthForPick =
      environmentState.renderTranslucentDepthForPick;
    var useWebVR = environmentState.useWebVR;

    // Do not render environment primitives during a pick pass since they do not generate picking commands.
    if (!picking) {
      var skyBoxCommand = environmentState.skyBoxCommand;
      if (defined(skyBoxCommand)) {
        executeCommand(skyBoxCommand, scene, context, passState);
      }

      if (environmentState.isSkyAtmosphereVisible) {
        executeCommand(
          environmentState.skyAtmosphereCommand,
          scene,
          context,
          passState
        );
      }

      if (environmentState.isSunVisible) {
        environmentState.sunDrawCommand.execute(context, passState);
        if (scene.sunBloom && !useWebVR) {
          var framebuffer;
          if (environmentState.useGlobeDepthFramebuffer) {
            framebuffer = view.globeDepth.framebuffer;
          } else if (environmentState.usePostProcess) {
            framebuffer = view.sceneFramebuffer.getFramebuffer();
          } else {
            framebuffer = environmentState.originalFramebuffer;
          }
          scene._sunPostProcess.execute(context);
          scene._sunPostProcess.copy(context, framebuffer);
          passState.framebuffer = framebuffer;
        }
      }

      // Moon can be seen through the atmosphere, since the sun is rendered after the atmosphere.
      if (environmentState.isMoonVisible) {
        environmentState.moonCommand.execute(context, passState);
      }
    }

    // Determine how translucent surfaces will be handled.
    var executeTranslucentCommands;
    if (environmentState.useOIT) {
      if (!defined(scene._executeOITFunction)) {
        scene._executeOITFunction = function (
          scene,
          executeFunction,
          passState,
          commands,
          invertClassification
        ) {
          view.oit.executeCommands(
            scene,
            executeFunction,
            passState,
            commands,
            invertClassification
          );
        };
      }
      executeTranslucentCommands = scene._executeOITFunction;
    } else if (passes.render) {
      executeTranslucentCommands = executeTranslucentCommandsBackToFront;
    } else {
      executeTranslucentCommands = executeTranslucentCommandsFrontToBack;
    }

    var frustumCommandsList = view.frustumCommandsList;
    var numFrustums = frustumCommandsList.length;

    var clearGlobeDepth = environmentState.clearGlobeDepth;
    var useDepthPlane = environmentState.useDepthPlane;
    var globeTranslucencyState = scene._globeTranslucencyState;
    var globeTranslucent = globeTranslucencyState.translucent;
    var globeTranslucencyFramebuffer = scene._view.globeTranslucencyFramebuffer;
    var separatePrimitiveFramebuffer = (environmentState.separatePrimitiveFramebuffer = false);
    var clearDepth = scene._depthClearCommand;
    var clearStencil = scene._stencilClearCommand;
    var clearClassificationStencil = scene._classificationStencilClearCommand;
    var depthPlane = scene._depthPlane;
    var usePostProcessSelected = environmentState.usePostProcessSelected;

    var height2D = camera.position.z;

    // Execute commands in each frustum in back to front order
    var j;
    for (var i = 0; i < numFrustums; ++i) {
      var index = numFrustums - i - 1;
      var frustumCommands = frustumCommandsList[index];

      if (scene.mode === SceneMode$1.SCENE2D) {
        // To avoid z-fighting in 2D, move the camera to just before the frustum
        // and scale the frustum depth to be in [1.0, nearToFarDistance2D].
        camera.position.z = height2D - frustumCommands.near + 1.0;
        frustum.far = Math.max(1.0, frustumCommands.far - frustumCommands.near);
        frustum.near = 1.0;
        us.update(frameState);
        us.updateFrustum(frustum);
      } else {
        // Avoid tearing artifacts between adjacent frustums in the opaque passes
        frustum.near =
          index !== 0
            ? frustumCommands.near * scene.opaqueFrustumNearOffset
            : frustumCommands.near;
        frustum.far = frustumCommands.far;
        us.updateFrustum(frustum);
      }

      var globeDepth = scene.debugShowGlobeDepth
        ? getDebugGlobeDepth(scene, index)
        : view.globeDepth;

      if (separatePrimitiveFramebuffer) {
        // Render to globe framebuffer in GLOBE pass
        passState.framebuffer = globeDepth.framebuffer;
      }

      var fb;
      if (
        scene.debugShowGlobeDepth &&
        defined(globeDepth) &&
        environmentState.useGlobeDepthFramebuffer
      ) {
        globeDepth.update(
          context,
          passState,
          view.viewport,
          scene._hdr,
          clearGlobeDepth
        );
        globeDepth.clear(context, passState, scene._clearColorCommand.color);
        fb = passState.framebuffer;
        passState.framebuffer = globeDepth.framebuffer;
      }

      clearDepth.execute(context, passState);

      if (context.stencilBuffer) {
        clearStencil.execute(context, passState);
      }

      us.updatePass(Pass$1.GLOBE);
      var commands = frustumCommands.commands[Pass$1.GLOBE];
      var length = frustumCommands.indices[Pass$1.GLOBE];

      if (globeTranslucent) {
        globeTranslucencyState.executeGlobeCommands(
          frustumCommands,
          executeCommand,
          globeTranslucencyFramebuffer,
          scene,
          passState
        );
      } else {
        for (j = 0; j < length; ++j) {
          executeCommand(commands[j], scene, context, passState);
        }
      }

      if (defined(globeDepth) && environmentState.useGlobeDepthFramebuffer) {
        globeDepth.executeCopyDepth(context, passState);
      }

      if (
        scene.debugShowGlobeDepth &&
        defined(globeDepth) &&
        environmentState.useGlobeDepthFramebuffer
      ) {
        passState.framebuffer = fb;
      }

      // Draw terrain classification
      if (!environmentState.renderTranslucentDepthForPick) {
        us.updatePass(Pass$1.TERRAIN_CLASSIFICATION);
        commands = frustumCommands.commands[Pass$1.TERRAIN_CLASSIFICATION];
        length = frustumCommands.indices[Pass$1.TERRAIN_CLASSIFICATION];

        if (globeTranslucent) {
          globeTranslucencyState.executeGlobeClassificationCommands(
            frustumCommands,
            executeCommand,
            globeTranslucencyFramebuffer,
            scene,
            passState
          );
        } else {
          for (j = 0; j < length; ++j) {
            executeCommand(commands[j], scene, context, passState);
          }
        }
      }

      if (clearGlobeDepth) {
        clearDepth.execute(context, passState);
        if (useDepthPlane) {
          depthPlane.execute(context, passState);
        }
      }

      if (separatePrimitiveFramebuffer) {
        // Render to primitive framebuffer in all other passes
        passState.framebuffer = globeDepth.primitiveFramebuffer;
      }

      if (
        !environmentState.useInvertClassification ||
        picking ||
        environmentState.renderTranslucentDepthForPick
      ) {
        // Common/fastest path. Draw 3D Tiles and classification normally.

        // Draw 3D Tiles
        us.updatePass(Pass$1.CESIUM_3D_TILE);
        commands = frustumCommands.commands[Pass$1.CESIUM_3D_TILE];
        length = frustumCommands.indices[Pass$1.CESIUM_3D_TILE];
        for (j = 0; j < length; ++j) {
          executeCommand(commands[j], scene, context, passState);
        }

        if (length > 0) {
          if (defined(globeDepth) && environmentState.useGlobeDepthFramebuffer) {
            globeDepth.executeUpdateDepth(context, passState, clearGlobeDepth);
          }

          // Draw classifications. Modifies 3D Tiles color.
          if (!environmentState.renderTranslucentDepthForPick) {
            us.updatePass(Pass$1.CESIUM_3D_TILE_CLASSIFICATION);
            commands =
              frustumCommands.commands[Pass$1.CESIUM_3D_TILE_CLASSIFICATION];
            length = frustumCommands.indices[Pass$1.CESIUM_3D_TILE_CLASSIFICATION];
            for (j = 0; j < length; ++j) {
              executeCommand(commands[j], scene, context, passState);
            }
          }
        }
      } else {
        // When the invert classification color is opaque:
        //    Main FBO (FBO1):                   Main_Color   + Main_DepthStencil
        //    Invert classification FBO (FBO2) : Invert_Color + Main_DepthStencil
        //
        //    1. Clear FBO2 color to vec4(0.0) for each frustum
        //    2. Draw 3D Tiles to FBO2
        //    3. Draw classification to FBO2
        //    4. Fullscreen pass to FBO1, draw Invert_Color when:
        //           * Main_DepthStencil has the stencil bit set > 0 (classified)
        //    5. Fullscreen pass to FBO1, draw Invert_Color * czm_invertClassificationColor when:
        //           * Main_DepthStencil has stencil bit set to 0 (unclassified) and
        //           * Invert_Color !== vec4(0.0)
        //
        // When the invert classification color is translucent:
        //    Main FBO (FBO1):                  Main_Color         + Main_DepthStencil
        //    Invert classification FBO (FBO2): Invert_Color       + Invert_DepthStencil
        //    IsClassified FBO (FBO3):          IsClassified_Color + Invert_DepthStencil
        //
        //    1. Clear FBO2 and FBO3 color to vec4(0.0), stencil to 0, and depth to 1.0
        //    2. Draw 3D Tiles to FBO2
        //    3. Draw classification to FBO2
        //    4. Fullscreen pass to FBO3, draw any color when
        //           * Invert_DepthStencil has the stencil bit set > 0 (classified)
        //    5. Fullscreen pass to FBO1, draw Invert_Color when:
        //           * Invert_Color !== vec4(0.0) and
        //           * IsClassified_Color !== vec4(0.0)
        //    6. Fullscreen pass to FBO1, draw Invert_Color * czm_invertClassificationColor when:
        //           * Invert_Color !== vec4(0.0) and
        //           * IsClassified_Color === vec4(0.0)
        //
        // NOTE: Step six when translucent invert color occurs after the TRANSLUCENT pass
        //
        scene._invertClassification.clear(context, passState);

        var opaqueClassificationFramebuffer = passState.framebuffer;
        passState.framebuffer = scene._invertClassification._fbo;

        // Draw normally
        us.updatePass(Pass$1.CESIUM_3D_TILE);
        commands = frustumCommands.commands[Pass$1.CESIUM_3D_TILE];
        length = frustumCommands.indices[Pass$1.CESIUM_3D_TILE];
        for (j = 0; j < length; ++j) {
          executeCommand(commands[j], scene, context, passState);
        }

        if (defined(globeDepth) && environmentState.useGlobeDepthFramebuffer) {
          globeDepth.executeUpdateDepth(context, passState, clearGlobeDepth);
        }

        // Set stencil
        us.updatePass(Pass$1.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW);
        commands =
          frustumCommands.commands[
            Pass$1.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW
          ];
        length =
          frustumCommands.indices[Pass$1.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW];
        for (j = 0; j < length; ++j) {
          executeCommand(commands[j], scene, context, passState);
        }

        passState.framebuffer = opaqueClassificationFramebuffer;

        // Fullscreen pass to copy classified fragments
        scene._invertClassification.executeClassified(context, passState);
        if (frameState.invertClassificationColor.alpha === 1.0) {
          // Fullscreen pass to copy unclassified fragments when alpha == 1.0
          scene._invertClassification.executeUnclassified(context, passState);
        }

        // Clear stencil set by the classification for the next classification pass
        if (length > 0 && context.stencilBuffer) {
          clearClassificationStencil.execute(context, passState);
        }

        // Draw style over classification.
        us.updatePass(Pass$1.CESIUM_3D_TILE_CLASSIFICATION);
        commands = frustumCommands.commands[Pass$1.CESIUM_3D_TILE_CLASSIFICATION];
        length = frustumCommands.indices[Pass$1.CESIUM_3D_TILE_CLASSIFICATION];
        for (j = 0; j < length; ++j) {
          executeCommand(commands[j], scene, context, passState);
        }
      }

      if (length > 0 && context.stencilBuffer) {
        clearStencil.execute(context, passState);
      }

      us.updatePass(Pass$1.OPAQUE);
      commands = frustumCommands.commands[Pass$1.OPAQUE];
      length = frustumCommands.indices[Pass$1.OPAQUE];
      for (j = 0; j < length; ++j) {
        executeCommand(commands[j], scene, context, passState);
      }

      if (index !== 0 && scene.mode !== SceneMode$1.SCENE2D) {
        // Do not overlap frustums in the translucent pass to avoid blending artifacts
        frustum.near = frustumCommands.near;
        us.updateFrustum(frustum);
      }

      var invertClassification;
      if (
        !picking &&
        environmentState.useInvertClassification &&
        frameState.invertClassificationColor.alpha < 1.0
      ) {
        // Fullscreen pass to copy unclassified fragments when alpha < 1.0.
        // Not executed when undefined.
        invertClassification = scene._invertClassification;
      }

      us.updatePass(Pass$1.TRANSLUCENT);
      commands = frustumCommands.commands[Pass$1.TRANSLUCENT];
      commands.length = frustumCommands.indices[Pass$1.TRANSLUCENT];
      executeTranslucentCommands(
        scene,
        executeCommand,
        passState,
        commands,
        invertClassification
      );

      if (
        context.depthTexture &&
        scene.useDepthPicking &&
        (environmentState.useGlobeDepthFramebuffer ||
          renderTranslucentDepthForPick)
      ) {
        // PERFORMANCE_IDEA: Use MRT to avoid the extra copy.
        var depthStencilTexture = renderTranslucentDepthForPick
          ? passState.framebuffer.depthStencilTexture
          : globeDepth.framebuffer.depthStencilTexture;
        var pickDepth = scene._picking.getPickDepth(scene, index);
        pickDepth.update(context, depthStencilTexture);
        pickDepth.executeCopyDepth(context, passState);
      }

      if (separatePrimitiveFramebuffer) {
        // Reset framebuffer
        passState.framebuffer = globeDepth.framebuffer;
      }

      if (picking || !usePostProcessSelected) {
        continue;
      }

      var originalFramebuffer = passState.framebuffer;
      passState.framebuffer = view.sceneFramebuffer.getIdFramebuffer();

      // reset frustum
      frustum.near =
        index !== 0
          ? frustumCommands.near * scene.opaqueFrustumNearOffset
          : frustumCommands.near;
      frustum.far = frustumCommands.far;
      us.updateFrustum(frustum);

      us.updatePass(Pass$1.GLOBE);
      commands = frustumCommands.commands[Pass$1.GLOBE];
      length = frustumCommands.indices[Pass$1.GLOBE];

      if (globeTranslucent) {
        globeTranslucencyState.executeGlobeCommands(
          frustumCommands,
          executeIdCommand,
          globeTranslucencyFramebuffer,
          scene,
          passState
        );
      } else {
        for (j = 0; j < length; ++j) {
          executeIdCommand(commands[j], scene, context, passState);
        }
      }

      if (clearGlobeDepth) {
        clearDepth.framebuffer = passState.framebuffer;
        clearDepth.execute(context, passState);
        clearDepth.framebuffer = undefined;
      }

      if (clearGlobeDepth && useDepthPlane) {
        depthPlane.execute(context, passState);
      }

      us.updatePass(Pass$1.CESIUM_3D_TILE);
      commands = frustumCommands.commands[Pass$1.CESIUM_3D_TILE];
      length = frustumCommands.indices[Pass$1.CESIUM_3D_TILE];
      for (j = 0; j < length; ++j) {
        executeIdCommand(commands[j], scene, context, passState);
      }

      us.updatePass(Pass$1.OPAQUE);
      commands = frustumCommands.commands[Pass$1.OPAQUE];
      length = frustumCommands.indices[Pass$1.OPAQUE];
      for (j = 0; j < length; ++j) {
        executeIdCommand(commands[j], scene, context, passState);
      }

      us.updatePass(Pass$1.TRANSLUCENT);
      commands = frustumCommands.commands[Pass$1.TRANSLUCENT];
      length = frustumCommands.indices[Pass$1.TRANSLUCENT];
      for (j = 0; j < length; ++j) {
        executeIdCommand(commands[j], scene, context, passState);
      }

      passState.framebuffer = originalFramebuffer;
    }
  }

  function executeComputeCommands(scene) {
    var us = scene.context.uniformState;
    us.updatePass(Pass$1.COMPUTE);

    var sunComputeCommand = scene._environmentState.sunComputeCommand;
    if (defined(sunComputeCommand)) {
      sunComputeCommand.execute(scene._computeEngine);
    }

    var commandList = scene._computeCommandList;
    var length = commandList.length;
    for (var i = 0; i < length; ++i) {
      commandList[i].execute(scene._computeEngine);
    }
  }

  function executeOverlayCommands(scene, passState) {
    var us = scene.context.uniformState;
    us.updatePass(Pass$1.OVERLAY);

    var context = scene.context;
    var commandList = scene._overlayCommandList;
    var length = commandList.length;
    for (var i = 0; i < length; ++i) {
      commandList[i].execute(context, passState);
    }
  }

  function insertShadowCastCommands(scene, commandList, shadowMap) {
    var shadowVolume = shadowMap.shadowMapCullingVolume;
    var isPointLight = shadowMap.isPointLight;
    var passes = shadowMap.passes;
    var numberOfPasses = passes.length;

    var length = commandList.length;
    for (var i = 0; i < length; ++i) {
      var command = commandList[i];
      scene.updateDerivedCommands(command);

      if (
        command.castShadows &&
        (command.pass === Pass$1.GLOBE ||
          command.pass === Pass$1.CESIUM_3D_TILE ||
          command.pass === Pass$1.OPAQUE ||
          command.pass === Pass$1.TRANSLUCENT)
      ) {
        if (scene.isVisible(command, shadowVolume)) {
          if (isPointLight) {
            for (var k = 0; k < numberOfPasses; ++k) {
              passes[k].commandList.push(command);
            }
          } else if (numberOfPasses === 1) {
            passes[0].commandList.push(command);
          } else {
            var wasVisible = false;
            // Loop over cascades from largest to smallest
            for (var j = numberOfPasses - 1; j >= 0; --j) {
              var cascadeVolume = passes[j].cullingVolume;
              if (scene.isVisible(command, cascadeVolume)) {
                passes[j].commandList.push(command);
                wasVisible = true;
              } else if (wasVisible) {
                // If it was visible in the previous cascade but now isn't
                // then there is no need to check any more cascades
                break;
              }
            }
          }
        }
      }
    }
  }

  function executeShadowMapCastCommands(scene) {
    var frameState = scene.frameState;
    var shadowMaps = frameState.shadowState.shadowMaps;
    var shadowMapLength = shadowMaps.length;

    if (!frameState.shadowState.shadowsEnabled) {
      return;
    }

    var context = scene.context;
    var uniformState = context.uniformState;

    for (var i = 0; i < shadowMapLength; ++i) {
      var shadowMap = shadowMaps[i];
      if (shadowMap.outOfView) {
        continue;
      }

      // Reset the command lists
      var j;
      var passes = shadowMap.passes;
      var numberOfPasses = passes.length;
      for (j = 0; j < numberOfPasses; ++j) {
        passes[j].commandList.length = 0;
      }

      // Insert the primitive/model commands into the command lists
      var sceneCommands = scene.frameState.commandList;
      insertShadowCastCommands(scene, sceneCommands, shadowMap);

      for (j = 0; j < numberOfPasses; ++j) {
        var pass = shadowMap.passes[j];
        uniformState.updateCamera(pass.camera);
        shadowMap.updatePass(context, j);
        var numberOfCommands = pass.commandList.length;
        for (var k = 0; k < numberOfCommands; ++k) {
          var command = pass.commandList[k];
          // Set the correct pass before rendering into the shadow map because some shaders
          // conditionally render based on whether the pass is translucent or opaque.
          uniformState.updatePass(command.pass);
          executeCommand(
            command.derivedCommands.shadows.castCommands[i],
            scene,
            context,
            pass.passState
          );
        }
      }
    }
  }

  var scratchEyeTranslation = new Cartesian3();

  /**
   * @private
   */
  Scene.prototype.updateAndExecuteCommands = function (
    passState,
    backgroundColor
  ) {
    var frameState = this._frameState;
    var mode = frameState.mode;
    var useWebVR = this._environmentState.useWebVR;

    if (useWebVR) {
      executeWebVRCommands(this, passState, backgroundColor);
    } else if (
      mode !== SceneMode$1.SCENE2D ||
      this._mapMode2D === MapMode2D$1.ROTATE
    ) {
      executeCommandsInViewport(true, this, passState, backgroundColor);
    } else {
      updateAndClearFramebuffers(this, passState, backgroundColor);
      execute2DViewportCommands(this, passState);
    }
  };

  function executeWebVRCommands(scene, passState, backgroundColor) {
    var view = scene._view;
    var camera = view.camera;
    var environmentState = scene._environmentState;
    var renderTranslucentDepthForPick =
      environmentState.renderTranslucentDepthForPick;

    updateAndClearFramebuffers(scene, passState, backgroundColor);

    if (!renderTranslucentDepthForPick) {
      updateAndRenderPrimitives(scene);
    }

    view.createPotentiallyVisibleSet(scene);

    if (!renderTranslucentDepthForPick) {
      executeComputeCommands(scene);
      executeShadowMapCastCommands(scene);
    }

    // Based on Calculating Stereo pairs by Paul Bourke
    // http://paulbourke.net/stereographics/stereorender/
    var viewport = passState.viewport;
    viewport.x = 0;
    viewport.y = 0;
    viewport.width = viewport.width * 0.5;

    var savedCamera = Camera.clone(camera, scene._cameraVR);
    savedCamera.frustum = camera.frustum;

    var near = camera.frustum.near;
    var fo = near * defaultValue(scene.focalLength, 5.0);
    var eyeSeparation = defaultValue(scene.eyeSeparation, fo / 30.0);
    var eyeTranslation = Cartesian3.multiplyByScalar(
      savedCamera.right,
      eyeSeparation * 0.5,
      scratchEyeTranslation
    );

    camera.frustum.aspectRatio = viewport.width / viewport.height;

    var offset = (0.5 * eyeSeparation * near) / fo;

    Cartesian3.add(savedCamera.position, eyeTranslation, camera.position);
    camera.frustum.xOffset = offset;

    executeCommands$1(scene, passState);

    viewport.x = viewport.width;

    Cartesian3.subtract(savedCamera.position, eyeTranslation, camera.position);
    camera.frustum.xOffset = -offset;

    executeCommands$1(scene, passState);

    Camera.clone(savedCamera, camera);
  }

  var scratch2DViewportCartographic = new Cartographic(
    Math.PI,
    CesiumMath.PI_OVER_TWO
  );
  var scratch2DViewportMaxCoord = new Cartesian3();
  var scratch2DViewportSavedPosition = new Cartesian3();
  var scratch2DViewportTransform = new Matrix4();
  var scratch2DViewportCameraTransform = new Matrix4();
  var scratch2DViewportEyePoint = new Cartesian3();
  var scratch2DViewportWindowCoords = new Cartesian3();
  var scratch2DViewport = new BoundingRectangle();

  function execute2DViewportCommands(scene, passState) {
    var context = scene.context;
    var frameState = scene.frameState;
    var camera = scene.camera;

    var originalViewport = passState.viewport;
    var viewport = BoundingRectangle.clone(originalViewport, scratch2DViewport);
    passState.viewport = viewport;

    var maxCartographic = scratch2DViewportCartographic;
    var maxCoord = scratch2DViewportMaxCoord;

    var projection = scene.mapProjection;
    projection.project(maxCartographic, maxCoord);

    var position = Cartesian3.clone(
      camera.position,
      scratch2DViewportSavedPosition
    );
    var transform = Matrix4.clone(
      camera.transform,
      scratch2DViewportCameraTransform
    );
    var frustum = camera.frustum.clone();

    camera._setTransform(Matrix4.IDENTITY);

    var viewportTransformation = Matrix4.computeViewportTransformation(
      viewport,
      0.0,
      1.0,
      scratch2DViewportTransform
    );
    var projectionMatrix = camera.frustum.projectionMatrix;

    var x = camera.positionWC.y;
    var eyePoint = Cartesian3.fromElements(
      CesiumMath.sign(x) * maxCoord.x - x,
      0.0,
      -camera.positionWC.x,
      scratch2DViewportEyePoint
    );
    var windowCoordinates = Transforms.pointToGLWindowCoordinates(
      projectionMatrix,
      viewportTransformation,
      eyePoint,
      scratch2DViewportWindowCoords
    );

    windowCoordinates.x = Math.floor(windowCoordinates.x);

    var viewportX = viewport.x;
    var viewportWidth = viewport.width;

    if (
      x === 0.0 ||
      windowCoordinates.x <= viewportX ||
      windowCoordinates.x >= viewportX + viewportWidth
    ) {
      executeCommandsInViewport(true, scene, passState);
    } else if (
      Math.abs(viewportX + viewportWidth * 0.5 - windowCoordinates.x) < 1.0
    ) {
      viewport.width = windowCoordinates.x - viewport.x;

      camera.position.x *= CesiumMath.sign(camera.position.x);

      camera.frustum.right = 0.0;

      frameState.cullingVolume = camera.frustum.computeCullingVolume(
        camera.positionWC,
        camera.directionWC,
        camera.upWC
      );
      context.uniformState.update(frameState);

      executeCommandsInViewport(true, scene, passState);

      viewport.x = windowCoordinates.x;

      camera.position.x = -camera.position.x;

      camera.frustum.right = -camera.frustum.left;
      camera.frustum.left = 0.0;

      frameState.cullingVolume = camera.frustum.computeCullingVolume(
        camera.positionWC,
        camera.directionWC,
        camera.upWC
      );
      context.uniformState.update(frameState);

      executeCommandsInViewport(false, scene, passState);
    } else if (windowCoordinates.x > viewportX + viewportWidth * 0.5) {
      viewport.width = windowCoordinates.x - viewportX;

      var right = camera.frustum.right;
      camera.frustum.right = maxCoord.x - x;

      frameState.cullingVolume = camera.frustum.computeCullingVolume(
        camera.positionWC,
        camera.directionWC,
        camera.upWC
      );
      context.uniformState.update(frameState);

      executeCommandsInViewport(true, scene, passState);

      viewport.x = windowCoordinates.x;
      viewport.width = viewportX + viewportWidth - windowCoordinates.x;

      camera.position.x = -camera.position.x;

      camera.frustum.left = -camera.frustum.right;
      camera.frustum.right = right - camera.frustum.right * 2.0;

      frameState.cullingVolume = camera.frustum.computeCullingVolume(
        camera.positionWC,
        camera.directionWC,
        camera.upWC
      );
      context.uniformState.update(frameState);

      executeCommandsInViewport(false, scene, passState);
    } else {
      viewport.x = windowCoordinates.x;
      viewport.width = viewportX + viewportWidth - windowCoordinates.x;

      var left = camera.frustum.left;
      camera.frustum.left = -maxCoord.x - x;

      frameState.cullingVolume = camera.frustum.computeCullingVolume(
        camera.positionWC,
        camera.directionWC,
        camera.upWC
      );
      context.uniformState.update(frameState);

      executeCommandsInViewport(true, scene, passState);

      viewport.x = viewportX;
      viewport.width = windowCoordinates.x - viewportX;

      camera.position.x = -camera.position.x;

      camera.frustum.right = -camera.frustum.left;
      camera.frustum.left = left - camera.frustum.left * 2.0;

      frameState.cullingVolume = camera.frustum.computeCullingVolume(
        camera.positionWC,
        camera.directionWC,
        camera.upWC
      );
      context.uniformState.update(frameState);

      executeCommandsInViewport(false, scene, passState);
    }

    camera._setTransform(transform);
    Cartesian3.clone(position, camera.position);
    camera.frustum = frustum.clone();
    passState.viewport = originalViewport;
  }

  function executeCommandsInViewport(
    firstViewport,
    scene,
    passState,
    backgroundColor
  ) {
    var environmentState = scene._environmentState;
    var view = scene._view;
    var renderTranslucentDepthForPick =
      environmentState.renderTranslucentDepthForPick;

    if (!firstViewport && !renderTranslucentDepthForPick) {
      scene.frameState.commandList.length = 0;
    }

    if (!renderTranslucentDepthForPick) {
      updateAndRenderPrimitives(scene);
    }

    view.createPotentiallyVisibleSet(scene);

    if (firstViewport) {
      if (defined(backgroundColor)) {
        updateAndClearFramebuffers(scene, passState, backgroundColor);
      }
      if (!renderTranslucentDepthForPick) {
        executeComputeCommands(scene);
        executeShadowMapCastCommands(scene);
      }
    }

    executeCommands$1(scene, passState);
  }

  var scratchCullingVolume$1 = new CullingVolume();

  /**
   * @private
   */
  Scene.prototype.updateEnvironment = function () {
    var frameState = this._frameState;
    var view = this._view;

    // Update celestial and terrestrial environment effects.
    var environmentState = this._environmentState;
    var renderPass = frameState.passes.render;
    var offscreenPass = frameState.passes.offscreen;
    var skyAtmosphere = this.skyAtmosphere;
    var globe = this.globe;
    var globeTranslucencyState = this._globeTranslucencyState;

    if (
      !renderPass ||
      (this._mode !== SceneMode$1.SCENE2D &&
        view.camera.frustum instanceof OrthographicFrustum) ||
      !globeTranslucencyState.environmentVisible
    ) {
      environmentState.skyAtmosphereCommand = undefined;
      environmentState.skyBoxCommand = undefined;
      environmentState.sunDrawCommand = undefined;
      environmentState.sunComputeCommand = undefined;
      environmentState.moonCommand = undefined;
    } else {
      if (defined(skyAtmosphere)) {
        if (defined(globe)) {
          skyAtmosphere.setDynamicAtmosphereColor(
            globe.enableLighting && globe.dynamicAtmosphereLighting,
            globe.dynamicAtmosphereLightingFromSun
          );
          environmentState.isReadyForAtmosphere =
            environmentState.isReadyForAtmosphere ||
            globe._surface._tilesToRender.length > 0;
        }
        environmentState.skyAtmosphereCommand = skyAtmosphere.update(
          frameState,
          globe
        );
        if (defined(environmentState.skyAtmosphereCommand)) {
          this.updateDerivedCommands(environmentState.skyAtmosphereCommand);
        }
      } else {
        environmentState.skyAtmosphereCommand = undefined;
      }

      environmentState.skyBoxCommand = defined(this.skyBox)
        ? this.skyBox.update(frameState, this._hdr)
        : undefined;
      var sunCommands = defined(this.sun)
        ? this.sun.update(frameState, view.passState, this._hdr)
        : undefined;
      environmentState.sunDrawCommand = defined(sunCommands)
        ? sunCommands.drawCommand
        : undefined;
      environmentState.sunComputeCommand = defined(sunCommands)
        ? sunCommands.computeCommand
        : undefined;
      environmentState.moonCommand = defined(this.moon)
        ? this.moon.update(frameState)
        : undefined;
    }

    var clearGlobeDepth = (environmentState.clearGlobeDepth =
      defined(globe) &&
      globe.show &&
      (!globe.depthTestAgainstTerrain || this.mode === SceneMode$1.SCENE2D));
    var useDepthPlane = (environmentState.useDepthPlane =
      clearGlobeDepth &&
      this.mode === SceneMode$1.SCENE3D &&
      globeTranslucencyState.useDepthPlane);
    if (useDepthPlane) {
      // Update the depth plane that is rendered in 3D when the primitives are
      // not depth tested against terrain so primitives on the backface
      // of the globe are not picked.
      this._depthPlane.update(frameState);
    }

    environmentState.renderTranslucentDepthForPick = false;
    environmentState.useWebVR =
      this._useWebVR && this.mode !== SceneMode$1.SCENE2D && !offscreenPass;

    var occluder =
      frameState.mode === SceneMode$1.SCENE3D &&
      !globeTranslucencyState.sunVisibleThroughGlobe
        ? frameState.occluder
        : undefined;
    var cullingVolume = frameState.cullingVolume;

    // get user culling volume minus the far plane.
    var planes = scratchCullingVolume$1.planes;
    for (var k = 0; k < 5; ++k) {
      planes[k] = cullingVolume.planes[k];
    }
    cullingVolume = scratchCullingVolume$1;

    // Determine visibility of celestial and terrestrial environment effects.
    environmentState.isSkyAtmosphereVisible =
      defined(environmentState.skyAtmosphereCommand) &&
      environmentState.isReadyForAtmosphere;
    environmentState.isSunVisible = this.isVisible(
      environmentState.sunDrawCommand,
      cullingVolume,
      occluder
    );
    environmentState.isMoonVisible = this.isVisible(
      environmentState.moonCommand,
      cullingVolume,
      occluder
    );

    var envMaps = this.specularEnvironmentMaps;
    var envMapAtlas = this._specularEnvironmentMapAtlas;
    if (
      defined(envMaps) &&
      (!defined(envMapAtlas) || envMapAtlas.url !== envMaps)
    ) {
      envMapAtlas = envMapAtlas && envMapAtlas.destroy();
      this._specularEnvironmentMapAtlas = new OctahedralProjectedCubeMap(envMaps);
    } else if (!defined(envMaps) && defined(envMapAtlas)) {
      envMapAtlas.destroy();
      this._specularEnvironmentMapAtlas = undefined;
    }

    if (defined(this._specularEnvironmentMapAtlas)) {
      this._specularEnvironmentMapAtlas.update(frameState);
    }
  };

  function updateDebugFrustumPlanes(scene) {
    var frameState = scene._frameState;
    if (scene.debugShowFrustumPlanes !== scene._debugShowFrustumPlanes) {
      if (scene.debugShowFrustumPlanes) {
        scene._debugFrustumPlanes = new DebugCameraPrimitive({
          camera: scene.camera,
          updateOnChange: false,
          frustumSplits: frameState.frustumSplits,
        });
      } else {
        scene._debugFrustumPlanes =
          scene._debugFrustumPlanes && scene._debugFrustumPlanes.destroy();
      }
      scene._debugShowFrustumPlanes = scene.debugShowFrustumPlanes;
    }

    if (defined(scene._debugFrustumPlanes)) {
      scene._debugFrustumPlanes.update(frameState);
    }
  }

  function updateShadowMaps(scene) {
    var frameState = scene._frameState;
    var shadowMaps = frameState.shadowMaps;
    var length = shadowMaps.length;

    var shadowsEnabled =
      length > 0 && !frameState.passes.pick && scene.mode === SceneMode$1.SCENE3D;
    if (shadowsEnabled !== frameState.shadowState.shadowsEnabled) {
      // Update derived commands when shadowsEnabled changes
      ++frameState.shadowState.lastDirtyTime;
      frameState.shadowState.shadowsEnabled = shadowsEnabled;
    }

    frameState.shadowState.lightShadowsEnabled = false;

    if (!shadowsEnabled) {
      return;
    }

    // Check if the shadow maps are different than the shadow maps last frame.
    // If so, the derived commands need to be updated.
    for (var j = 0; j < length; ++j) {
      if (shadowMaps[j] !== frameState.shadowState.shadowMaps[j]) {
        ++frameState.shadowState.lastDirtyTime;
        break;
      }
    }

    frameState.shadowState.shadowMaps.length = 0;
    frameState.shadowState.lightShadowMaps.length = 0;

    for (var i = 0; i < length; ++i) {
      var shadowMap = shadowMaps[i];
      shadowMap.update(frameState);

      frameState.shadowState.shadowMaps.push(shadowMap);

      if (shadowMap.fromLightSource) {
        frameState.shadowState.lightShadowMaps.push(shadowMap);
        frameState.shadowState.lightShadowsEnabled = true;
      }

      if (shadowMap.dirty) {
        ++frameState.shadowState.lastDirtyTime;
        shadowMap.dirty = false;
      }
    }
  }

  function updateAndRenderPrimitives(scene) {
    var frameState = scene._frameState;

    scene._groundPrimitives.update(frameState);
    scene._primitives.update(frameState);

    updateDebugFrustumPlanes(scene);
    updateShadowMaps(scene);

    if (scene._globe) {
      scene._globe.render(frameState);
    }
  }

  function updateAndClearFramebuffers(scene, passState, clearColor) {
    var context = scene._context;
    var frameState = scene._frameState;
    var environmentState = scene._environmentState;
    var view = scene._view;

    var passes = scene._frameState.passes;
    var picking = passes.pick;
    var useWebVR = environmentState.useWebVR;

    // Preserve the reference to the original framebuffer.
    environmentState.originalFramebuffer = passState.framebuffer;

    // Manage sun bloom post-processing effect.
    if (defined(scene.sun) && scene.sunBloom !== scene._sunBloom) {
      if (scene.sunBloom && !useWebVR) {
        scene._sunPostProcess = new SunPostProcess();
      } else if (defined(scene._sunPostProcess)) {
        scene._sunPostProcess = scene._sunPostProcess.destroy();
      }

      scene._sunBloom = scene.sunBloom;
    } else if (!defined(scene.sun) && defined(scene._sunPostProcess)) {
      scene._sunPostProcess = scene._sunPostProcess.destroy();
      scene._sunBloom = false;
    }

    // Clear the pass state framebuffer.
    var clear = scene._clearColorCommand;
    Color.clone(clearColor, clear.color);
    clear.execute(context, passState);

    // Update globe depth rendering based on the current context and clear the globe depth framebuffer.
    // Globe depth is copied for the pick pass to support picking batched geometries in GroundPrimitives.
    var useGlobeDepthFramebuffer = (environmentState.useGlobeDepthFramebuffer = defined(
      view.globeDepth
    ));
    if (useGlobeDepthFramebuffer) {
      view.globeDepth.update(
        context,
        passState,
        view.viewport,
        scene._hdr,
        environmentState.clearGlobeDepth
      );
      view.globeDepth.clear(context, passState, clearColor);
    }

    // If supported, configure OIT to use the globe depth framebuffer and clear the OIT framebuffer.
    var oit = view.oit;
    var useOIT = (environmentState.useOIT =
      !picking && defined(oit) && oit.isSupported());
    if (useOIT) {
      oit.update(context, passState, view.globeDepth.framebuffer, scene._hdr);
      oit.clear(context, passState, clearColor);
      environmentState.useOIT = oit.isSupported();
    }

    var postProcess = scene.postProcessStages;
    var usePostProcess = (environmentState.usePostProcess =
      !picking &&
      (scene._hdr ||
        postProcess.length > 0 ||
        postProcess.ambientOcclusion.enabled ||
        postProcess.fxaa.enabled ||
        postProcess.bloom.enabled));
    environmentState.usePostProcessSelected = false;
    if (usePostProcess) {
      view.sceneFramebuffer.update(context, view.viewport, scene._hdr);
      view.sceneFramebuffer.clear(context, passState, clearColor);

      postProcess.update(context, frameState.useLogDepth, scene._hdr);
      postProcess.clear(context);

      usePostProcess = environmentState.usePostProcess = postProcess.ready;
      environmentState.usePostProcessSelected =
        usePostProcess && postProcess.hasSelected;
    }

    if (environmentState.isSunVisible && scene.sunBloom && !useWebVR) {
      passState.framebuffer = scene._sunPostProcess.update(passState);
      scene._sunPostProcess.clear(context, passState, clearColor);
    } else if (useGlobeDepthFramebuffer) {
      passState.framebuffer = view.globeDepth.framebuffer;
    } else if (usePostProcess) {
      passState.framebuffer = view.sceneFramebuffer.getFramebuffer();
    }

    if (defined(passState.framebuffer)) {
      clear.execute(context, passState);
    }

    var useInvertClassification = (environmentState.useInvertClassification =
      !picking && defined(passState.framebuffer) && scene.invertClassification);
    if (useInvertClassification) {
      var depthFramebuffer;
      if (scene.frameState.invertClassificationColor.alpha === 1.0) {
        if (environmentState.useGlobeDepthFramebuffer) {
          depthFramebuffer = view.globeDepth.framebuffer;
        }
      }

      if (defined(depthFramebuffer) || context.depthTexture) {
        scene._invertClassification.previousFramebuffer = depthFramebuffer;
        scene._invertClassification.update(context);
        scene._invertClassification.clear(context, passState);

        if (scene.frameState.invertClassificationColor.alpha < 1.0 && useOIT) {
          var command = scene._invertClassification.unclassifiedCommand;
          var derivedCommands = command.derivedCommands;
          derivedCommands.oit = oit.createDerivedCommands(
            command,
            context,
            derivedCommands.oit
          );
        }
      } else {
        environmentState.useInvertClassification = false;
      }
    }

    if (scene._globeTranslucencyState.translucent) {
      view.globeTranslucencyFramebuffer.updateAndClear(
        scene._hdr,
        view.viewport,
        context,
        passState
      );
    }
  }

  /**
   * @private
   */
  Scene.prototype.resolveFramebuffers = function (passState) {
    var context = this._context;
    var frameState = this._frameState;
    var environmentState = this._environmentState;
    var view = this._view;
    var globeDepth = view.globeDepth;

    var useOIT = environmentState.useOIT;
    var useGlobeDepthFramebuffer = environmentState.useGlobeDepthFramebuffer;
    var usePostProcess = environmentState.usePostProcess;

    var defaultFramebuffer = environmentState.originalFramebuffer;
    var globeFramebuffer = useGlobeDepthFramebuffer
      ? globeDepth.framebuffer
      : undefined;
    var sceneFramebuffer = view.sceneFramebuffer.getFramebuffer();
    var idFramebuffer = view.sceneFramebuffer.getIdFramebuffer();

    if (environmentState.separatePrimitiveFramebuffer) {
      // Merge primitive framebuffer into globe framebuffer
      globeDepth.executeMergeColor(context, passState);
    }

    if (useOIT) {
      passState.framebuffer = usePostProcess
        ? sceneFramebuffer
        : defaultFramebuffer;
      view.oit.execute(context, passState);
    }

    if (usePostProcess) {
      var inputFramebuffer = sceneFramebuffer;
      if (useGlobeDepthFramebuffer && !useOIT) {
        inputFramebuffer = globeFramebuffer;
      }

      var postProcess = this.postProcessStages;
      var colorTexture = inputFramebuffer.getColorTexture(0);
      var idTexture = idFramebuffer.getColorTexture(0);
      var depthTexture = defaultValue(globeFramebuffer, sceneFramebuffer)
        .depthStencilTexture;
      postProcess.execute(context, colorTexture, depthTexture, idTexture);
      postProcess.copy(context, defaultFramebuffer);
    }

    if (!useOIT && !usePostProcess && useGlobeDepthFramebuffer) {
      passState.framebuffer = defaultFramebuffer;
      globeDepth.executeCopyColor(context, passState);
    }

    var useLogDepth = frameState.useLogDepth;

    if (this.debugShowGlobeDepth && useGlobeDepthFramebuffer) {
      var gd = getDebugGlobeDepth(this, this.debugShowDepthFrustum - 1);
      gd.executeDebugGlobeDepth(context, passState, useLogDepth);
    }

    if (this.debugShowPickDepth && useGlobeDepthFramebuffer) {
      var pd = this._picking.getPickDepth(this, this.debugShowDepthFrustum - 1);
      pd.executeDebugPickDepth(context, passState, useLogDepth);
    }
  };

  function callAfterRenderFunctions(scene) {
    // Functions are queued up during primitive update and executed here in case
    // the function modifies scene state that should remain constant over the frame.
    var functions = scene._frameState.afterRender;
    for (var i = 0, length = functions.length; i < length; ++i) {
      functions[i]();
      scene.requestRender();
    }

    functions.length = 0;
  }

  function getGlobeHeight(scene) {
    var globe = scene._globe;
    var camera = scene.camera;
    var cartographic = camera.positionCartographic;
    if (defined(globe) && globe.show && defined(cartographic)) {
      return globe.getHeight(cartographic);
    }
    return undefined;
  }

  function isCameraUnderground(scene) {
    var camera = scene.camera;
    var mode = scene._mode;
    var globe = scene.globe;
    var cameraController = scene._screenSpaceCameraController;
    var cartographic = camera.positionCartographic;

    if (!defined(cartographic)) {
      return false;
    }

    if (!cameraController.onMap() && cartographic.height < 0.0) {
      // The camera can go off the map while in Columbus View.
      // Make a best guess as to whether it's underground by checking if its height is less than zero.
      return true;
    }

    if (
      !defined(globe) ||
      !globe.show ||
      mode === SceneMode$1.SCENE2D ||
      mode === SceneMode$1.MORPHING
    ) {
      return false;
    }

    var globeHeight = scene._globeHeight;
    return defined(globeHeight) && cartographic.height < globeHeight;
  }

  /**
   * @private
   */
  Scene.prototype.initializeFrame = function () {
    // Destroy released shaders and textures once every 120 frames to avoid thrashing the cache
    if (this._shaderFrameCount++ === 120) {
      this._shaderFrameCount = 0;
      this._context.shaderCache.destroyReleasedShaderPrograms();
      this._context.textureCache.destroyReleasedTextures();
    }

    this._tweens.update();

    this._globeHeight = getGlobeHeight(this);
    this._cameraUnderground = isCameraUnderground(this);
    this._globeTranslucencyState.update(this);

    this._screenSpaceCameraController.update();
    if (defined(this._deviceOrientationCameraController)) {
      this._deviceOrientationCameraController.update();
    }

    this.camera.update(this._mode);
    this.camera._updateCameraChanged();
  };

  function updateDebugShowFramesPerSecond(scene, renderedThisFrame) {
    if (scene.debugShowFramesPerSecond) {
      if (!defined(scene._performanceDisplay)) {
        var performanceContainer = document.createElement("div");
        performanceContainer.className =
          "cesium-performanceDisplay-defaultContainer";
        var container = scene._canvas.parentNode;
        container.appendChild(performanceContainer);
        var performanceDisplay = new PerformanceDisplay({
          container: performanceContainer,
        });
        scene._performanceDisplay = performanceDisplay;
        scene._performanceContainer = performanceContainer;
      }

      scene._performanceDisplay.throttled = scene.requestRenderMode;
      scene._performanceDisplay.update(renderedThisFrame);
    } else if (defined(scene._performanceDisplay)) {
      scene._performanceDisplay =
        scene._performanceDisplay && scene._performanceDisplay.destroy();
      scene._performanceContainer.parentNode.removeChild(
        scene._performanceContainer
      );
    }
  }

  function prePassesUpdate(scene) {
    scene._jobScheduler.resetBudgets();

    var frameState = scene._frameState;
    var primitives = scene.primitives;
    primitives.prePassesUpdate(frameState);

    if (defined(scene.globe)) {
      scene.globe.update(frameState);
    }

    scene._picking.update();
    frameState.creditDisplay.update();
  }

  function postPassesUpdate(scene) {
    var frameState = scene._frameState;
    var primitives = scene.primitives;
    primitives.postPassesUpdate(frameState);

    RequestScheduler.update();
  }

  var scratchBackgroundColor = new Color();

  function render(scene) {
    var frameState = scene._frameState;

    var context = scene.context;
    var us = context.uniformState;

    var view = scene._defaultView;
    scene._view = view;

    scene.updateFrameState();
    frameState.passes.render = true;
    frameState.passes.postProcess = scene.postProcessStages.hasSelected;
    frameState.tilesetPassState = renderTilesetPassState;

    var backgroundColor = defaultValue(scene.backgroundColor, Color.BLACK);
    if (scene._hdr) {
      backgroundColor = Color.clone(backgroundColor, scratchBackgroundColor);
      backgroundColor.red = Math.pow(backgroundColor.red, scene.gamma);
      backgroundColor.green = Math.pow(backgroundColor.green, scene.gamma);
      backgroundColor.blue = Math.pow(backgroundColor.blue, scene.gamma);
    }
    frameState.backgroundColor = backgroundColor;

    scene.fog.update(frameState);

    us.update(frameState);

    var shadowMap = scene.shadowMap;
    if (defined(shadowMap) && shadowMap.enabled) {
      if (!defined(scene.light) || scene.light instanceof SunLight) {
        // Negate the sun direction so that it is from the Sun, not to the Sun
        Cartesian3.negate(us.sunDirectionWC, scene._shadowMapCamera.direction);
      } else {
        Cartesian3.clone(scene.light.direction, scene._shadowMapCamera.direction);
      }
      frameState.shadowMaps.push(shadowMap);
    }

    scene._computeCommandList.length = 0;
    scene._overlayCommandList.length = 0;

    var viewport = view.viewport;
    viewport.x = 0;
    viewport.y = 0;
    viewport.width = context.drawingBufferWidth;
    viewport.height = context.drawingBufferHeight;

    var passState = view.passState;
    passState.framebuffer = undefined;
    passState.blendingEnabled = undefined;
    passState.scissorTest = undefined;
    passState.viewport = BoundingRectangle.clone(viewport, passState.viewport);

    if (defined(scene.globe)) {
      scene.globe.beginFrame(frameState);
    }

    scene.updateEnvironment();
    scene.updateAndExecuteCommands(passState, backgroundColor);
    scene.resolveFramebuffers(passState);

    passState.framebuffer = undefined;
    executeOverlayCommands(scene, passState);

    if (defined(scene.globe)) {
      scene.globe.endFrame(frameState);

      if (!scene.globe.tilesLoaded) {
        scene._renderRequested = true;
      }
    }

    context.endFrame();
  }

  function tryAndCatchError(scene, functionToExecute) {
    try {
      functionToExecute(scene);
    } catch (error) {
      scene._renderError.raiseEvent(scene, error);

      if (scene.rethrowRenderErrors) {
        throw error;
      }
    }
  }

  function updateMostDetailedRayPicks(scene) {
    return scene._picking.updateMostDetailedRayPicks(scene);
  }

  /**
   * Update and render the scene. It is usually not necessary to call this function
   * directly because {@link CesiumWidget} or {@link Viewer} do it automatically.
   * @param {JulianDate} [time] The simulation time at which to render.
   */
  Scene.prototype.render = function (time) {
    /**
     *
     * Pre passes update. Execute any pass invariant code that should run before the passes here.
     *
     */
    this._preUpdate.raiseEvent(this, time);

    var frameState = this._frameState;
    frameState.newFrame = false;

    if (!defined(time)) {
      time = JulianDate.now();
    }

    // Determine if shouldRender
    var cameraChanged = this._view.checkForCameraUpdates(this);
    var shouldRender =
      !this.requestRenderMode ||
      this._renderRequested ||
      cameraChanged ||
      this._logDepthBufferDirty ||
      this._hdrDirty ||
      this.mode === SceneMode$1.MORPHING;
    if (
      !shouldRender &&
      defined(this.maximumRenderTimeChange) &&
      defined(this._lastRenderTime)
    ) {
      var difference = Math.abs(
        JulianDate.secondsDifference(this._lastRenderTime, time)
      );
      shouldRender = shouldRender || difference > this.maximumRenderTimeChange;
    }

    if (shouldRender) {
      this._lastRenderTime = JulianDate.clone(time, this._lastRenderTime);
      this._renderRequested = false;
      this._logDepthBufferDirty = false;
      this._hdrDirty = false;

      var frameNumber = CesiumMath.incrementWrap(
        frameState.frameNumber,
        15000000.0,
        1.0
      );
      updateFrameNumber(this, frameNumber, time);
      frameState.newFrame = true;
    }

    tryAndCatchError(this, prePassesUpdate);

    /**
     *
     * Passes update. Add any passes here
     *
     */
    if (this.primitives.show) {
      tryAndCatchError(this, updateMostDetailedRayPicks);
      tryAndCatchError(this, updatePreloadPass);
      tryAndCatchError(this, updatePreloadFlightPass);
      if (!shouldRender) {
        tryAndCatchError(this, updateRequestRenderModeDeferCheckPass);
      }
    }

    this._postUpdate.raiseEvent(this, time);

    if (shouldRender) {
      this._preRender.raiseEvent(this, time);
      frameState.creditDisplay.beginFrame();
      tryAndCatchError(this, render);
    }

    /**
     *
     * Post passes update. Execute any pass invariant code that should run after the passes here.
     *
     */
    updateDebugShowFramesPerSecond(this, shouldRender);
    tryAndCatchError(this, postPassesUpdate);

    // Often used to trigger events (so don't want in trycatch) that the user might be subscribed to. Things like the tile load events, ready promises, etc.
    // We don't want those events to resolve during the render loop because the events might add new primitives
    callAfterRenderFunctions(this);

    if (shouldRender) {
      this._postRender.raiseEvent(this, time);
      frameState.creditDisplay.endFrame();
    }
  };

  /**
   * Update and render the scene. Always forces a new render frame regardless of whether a render was
   * previously requested.
   * @param {JulianDate} [time] The simulation time at which to render.
   *
   * @private
   */
  Scene.prototype.forceRender = function (time) {
    this._renderRequested = true;
    this.render(time);
  };

  /**
   * Requests a new rendered frame when {@link Scene#requestRenderMode} is set to <code>true</code>.
   * The render rate will not exceed the {@link CesiumWidget#targetFrameRate}.
   *
   * @see Scene#requestRenderMode
   */
  Scene.prototype.requestRender = function () {
    this._renderRequested = true;
  };

  /**
   * @private
   */
  Scene.prototype.clampLineWidth = function (width) {
    return Math.max(
      ContextLimits.minimumAliasedLineWidth,
      Math.min(width, ContextLimits.maximumAliasedLineWidth)
    );
  };

  /**
   * Returns an object with a `primitive` property that contains the first (top) primitive in the scene
   * at a particular window coordinate or undefined if nothing is at the location. Other properties may
   * potentially be set depending on the type of primitive and may be used to further identify the picked object.
   * <p>
   * When a feature of a 3D Tiles tileset is picked, <code>pick</code> returns a {@link Cesium3DTileFeature} object.
   * </p>
   *
   * @example
   * // On mouse over, color the feature yellow.
   * handler.setInputAction(function(movement) {
   *     var feature = scene.pick(movement.endPosition);
   *     if (feature instanceof Cesium.Cesium3DTileFeature) {
   *         feature.color = Cesium.Color.YELLOW;
   *     }
   * }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
   *
   * @param {Cartesian2} windowPosition Window coordinates to perform picking on.
   * @param {Number} [width=3] Width of the pick rectangle.
   * @param {Number} [height=3] Height of the pick rectangle.
   * @returns {Object} Object containing the picked primitive.
   */
  Scene.prototype.pick = function (windowPosition, width, height) {
    return this._picking.pick(this, windowPosition, width, height);
  };

  /**
   * Returns the cartesian position reconstructed from the depth buffer and window position.
   * The returned position is in world coordinates. Used internally by camera functions to
   * prevent conversion to projected 2D coordinates and then back.
   * <p>
   * Set {@link Scene#pickTranslucentDepth} to <code>true</code> to include the depth of
   * translucent primitives; otherwise, this essentially picks through translucent primitives.
   * </p>
   *
   * @private
   *
   * @param {Cartesian2} windowPosition Window coordinates to perform picking on.
   * @param {Cartesian3} [result] The object on which to restore the result.
   * @returns {Cartesian3} The cartesian position in world coordinates.
   *
   * @exception {DeveloperError} Picking from the depth buffer is not supported. Check pickPositionSupported.
   */
  Scene.prototype.pickPositionWorldCoordinates = function (
    windowPosition,
    result
  ) {
    return this._picking.pickPositionWorldCoordinates(
      this,
      windowPosition,
      result
    );
  };

  /**
   * Returns the cartesian position reconstructed from the depth buffer and window position.
   * <p>
   * The position reconstructed from the depth buffer in 2D may be slightly different from those
   * reconstructed in 3D and Columbus view. This is caused by the difference in the distribution
   * of depth values of perspective and orthographic projection.
   * </p>
   * <p>
   * Set {@link Scene#pickTranslucentDepth} to <code>true</code> to include the depth of
   * translucent primitives; otherwise, this essentially picks through translucent primitives.
   * </p>
   *
   * @param {Cartesian2} windowPosition Window coordinates to perform picking on.
   * @param {Cartesian3} [result] The object on which to restore the result.
   * @returns {Cartesian3} The cartesian position.
   *
   * @exception {DeveloperError} Picking from the depth buffer is not supported. Check pickPositionSupported.
   */
  Scene.prototype.pickPosition = function (windowPosition, result) {
    return this._picking.pickPosition(this, windowPosition, result);
  };

  /**
   * Returns a list of objects, each containing a `primitive` property, for all primitives at
   * a particular window coordinate position. Other properties may also be set depending on the
   * type of primitive and may be used to further identify the picked object. The primitives in
   * the list are ordered by their visual order in the scene (front to back).
   *
   * @param {Cartesian2} windowPosition Window coordinates to perform picking on.
   * @param {Number} [limit] If supplied, stop drilling after collecting this many picks.
   * @param {Number} [width=3] Width of the pick rectangle.
   * @param {Number} [height=3] Height of the pick rectangle.
   * @returns {Array.<*>} Array of objects, each containing 1 picked primitives.
   *
   * @exception {DeveloperError} windowPosition is undefined.
   *
   * @example
   * var pickedObjects = scene.drillPick(new Cesium.Cartesian2(100.0, 200.0));
   *
   * @see Scene#pick
   */
  Scene.prototype.drillPick = function (windowPosition, limit, width, height) {
    return this._picking.drillPick(this, windowPosition, limit, width, height);
  };

  function updatePreloadPass(scene) {
    var frameState = scene._frameState;
    preloadTilesetPassState.camera = frameState.camera;
    preloadTilesetPassState.cullingVolume = frameState.cullingVolume;

    var primitives = scene.primitives;
    primitives.updateForPass(frameState, preloadTilesetPassState);
  }

  function updatePreloadFlightPass(scene) {
    var frameState = scene._frameState;
    var camera = frameState.camera;
    if (!camera.canPreloadFlight()) {
      return;
    }

    preloadFlightTilesetPassState.camera = scene.preloadFlightCamera;
    preloadFlightTilesetPassState.cullingVolume =
      scene.preloadFlightCullingVolume;

    var primitives = scene.primitives;
    primitives.updateForPass(frameState, preloadFlightTilesetPassState);
  }

  function updateRequestRenderModeDeferCheckPass(scene) {
    // Check if any ignored requests are ready to go (to wake rendering up again)
    scene.primitives.updateForPass(
      scene._frameState,
      requestRenderModeDeferCheckPassState
    );
  }

  /**
   * Returns an object containing the first object intersected by the ray and the position of intersection,
   * or <code>undefined</code> if there were no intersections. The intersected object has a <code>primitive</code>
   * property that contains the intersected primitive. Other properties may be set depending on the type of primitive
   * and may be used to further identify the picked object. The ray must be given in world coordinates.
   * <p>
   * This function only picks globe tiles and 3D Tiles that are rendered in the current view. Picks all other
   * primitives regardless of their visibility.
   * </p>
   *
   * @private
   *
   * @param {Ray} ray The ray.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to exclude from the ray intersection.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Object} An object containing the object and position of the first intersection.
   *
   * @exception {DeveloperError} Ray intersections are only supported in 3D mode.
   */
  Scene.prototype.pickFromRay = function (ray, objectsToExclude, width) {
    return this._picking.pickFromRay(this, ray, objectsToExclude, width);
  };

  /**
   * Returns a list of objects, each containing the object intersected by the ray and the position of intersection.
   * The intersected object has a <code>primitive</code> property that contains the intersected primitive. Other
   * properties may also be set depending on the type of primitive and may be used to further identify the picked object.
   * The primitives in the list are ordered by first intersection to last intersection. The ray must be given in
   * world coordinates.
   * <p>
   * This function only picks globe tiles and 3D Tiles that are rendered in the current view. Picks all other
   * primitives regardless of their visibility.
   * </p>
   *
   * @private
   *
   * @param {Ray} ray The ray.
   * @param {Number} [limit=Number.MAX_VALUE] If supplied, stop finding intersections after this many intersections.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to exclude from the ray intersection.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Object[]} List of objects containing the object and position of each intersection.
   *
   * @exception {DeveloperError} Ray intersections are only supported in 3D mode.
   */
  Scene.prototype.drillPickFromRay = function (
    ray,
    limit,
    objectsToExclude,
    width
  ) {
    return this._picking.drillPickFromRay(
      this,
      ray,
      limit,
      objectsToExclude,
      width
    );
  };

  /**
   * Initiates an asynchronous {@link Scene#pickFromRay} request using the maximum level of detail for 3D Tilesets
   * regardless of visibility.
   *
   * @private
   *
   * @param {Ray} ray The ray.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to exclude from the ray intersection.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Promise.<Object>} A promise that resolves to an object containing the object and position of the first intersection.
   *
   * @exception {DeveloperError} Ray intersections are only supported in 3D mode.
   */
  Scene.prototype.pickFromRayMostDetailed = function (
    ray,
    objectsToExclude,
    width
  ) {
    return this._picking.pickFromRayMostDetailed(
      this,
      ray,
      objectsToExclude,
      width
    );
  };

  /**
   * Initiates an asynchronous {@link Scene#drillPickFromRay} request using the maximum level of detail for 3D Tilesets
   * regardless of visibility.
   *
   * @private
   *
   * @param {Ray} ray The ray.
   * @param {Number} [limit=Number.MAX_VALUE] If supplied, stop finding intersections after this many intersections.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to exclude from the ray intersection.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Promise.<Object[]>} A promise that resolves to a list of objects containing the object and position of each intersection.
   *
   * @exception {DeveloperError} Ray intersections are only supported in 3D mode.
   */
  Scene.prototype.drillPickFromRayMostDetailed = function (
    ray,
    limit,
    objectsToExclude,
    width
  ) {
    return this._picking.drillPickFromRayMostDetailed(
      this,
      ray,
      limit,
      objectsToExclude,
      width
    );
  };

  /**
   * Returns the height of scene geometry at the given cartographic position or <code>undefined</code> if there was no
   * scene geometry to sample height from. The height of the input position is ignored. May be used to clamp objects to
   * the globe, 3D Tiles, or primitives in the scene.
   * <p>
   * This function only samples height from globe tiles and 3D Tiles that are rendered in the current view. Samples height
   * from all other primitives regardless of their visibility.
   * </p>
   *
   * @param {Cartographic} position The cartographic position to sample height from.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to not sample height from.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Number} The height. This may be <code>undefined</code> if there was no scene geometry to sample height from.
   *
   * @example
   * var position = new Cesium.Cartographic(-1.31968, 0.698874);
   * var height = viewer.scene.sampleHeight(position);
   * console.log(height);
   *
   * @see Scene#clampToHeight
   * @see Scene#clampToHeightMostDetailed
   * @see Scene#sampleHeightMostDetailed
   *
   * @exception {DeveloperError} sampleHeight is only supported in 3D mode.
   * @exception {DeveloperError} sampleHeight requires depth texture support. Check sampleHeightSupported.
   */
  Scene.prototype.sampleHeight = function (position, objectsToExclude, width) {
    return this._picking.sampleHeight(this, position, objectsToExclude, width);
  };

  /**
   * Clamps the given cartesian position to the scene geometry along the geodetic surface normal. Returns the
   * clamped position or <code>undefined</code> if there was no scene geometry to clamp to. May be used to clamp
   * objects to the globe, 3D Tiles, or primitives in the scene.
   * <p>
   * This function only clamps to globe tiles and 3D Tiles that are rendered in the current view. Clamps to
   * all other primitives regardless of their visibility.
   * </p>
   *
   * @param {Cartesian3} cartesian The cartesian position.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to not clamp to.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @param {Cartesian3} [result] An optional object to return the clamped position.
   * @returns {Cartesian3} The modified result parameter or a new Cartesian3 instance if one was not provided. This may be <code>undefined</code> if there was no scene geometry to clamp to.
   *
   * @example
   * // Clamp an entity to the underlying scene geometry
   * var position = entity.position.getValue(Cesium.JulianDate.now());
   * entity.position = viewer.scene.clampToHeight(position);
   *
   * @see Scene#sampleHeight
   * @see Scene#sampleHeightMostDetailed
   * @see Scene#clampToHeightMostDetailed
   *
   * @exception {DeveloperError} clampToHeight is only supported in 3D mode.
   * @exception {DeveloperError} clampToHeight requires depth texture support. Check clampToHeightSupported.
   */
  Scene.prototype.clampToHeight = function (
    cartesian,
    objectsToExclude,
    width,
    result
  ) {
    return this._picking.clampToHeight(
      this,
      cartesian,
      objectsToExclude,
      width,
      result
    );
  };

  /**
   * Initiates an asynchronous {@link Scene#sampleHeight} query for an array of {@link Cartographic} positions
   * using the maximum level of detail for 3D Tilesets in the scene. The height of the input positions is ignored.
   * Returns a promise that is resolved when the query completes. Each point height is modified in place.
   * If a height cannot be determined because no geometry can be sampled at that location, or another error occurs,
   * the height is set to undefined.
   *
   * @param {Cartographic[]} positions The cartographic positions to update with sampled heights.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to not sample height from.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Promise.<Cartographic[]>} A promise that resolves to the provided list of positions when the query has completed.
   *
   * @example
   * var positions = [
   *     new Cesium.Cartographic(-1.31968, 0.69887),
   *     new Cesium.Cartographic(-1.10489, 0.83923)
   * ];
   * var promise = viewer.scene.sampleHeightMostDetailed(positions);
   * promise.then(function(updatedPosition) {
   *     // positions[0].height and positions[1].height have been updated.
   *     // updatedPositions is just a reference to positions.
   * }
   *
   * @see Scene#sampleHeight
   *
   * @exception {DeveloperError} sampleHeightMostDetailed is only supported in 3D mode.
   * @exception {DeveloperError} sampleHeightMostDetailed requires depth texture support. Check sampleHeightSupported.
   */
  Scene.prototype.sampleHeightMostDetailed = function (
    positions,
    objectsToExclude,
    width
  ) {
    return this._picking.sampleHeightMostDetailed(
      this,
      positions,
      objectsToExclude,
      width
    );
  };

  /**
   * Initiates an asynchronous {@link Scene#clampToHeight} query for an array of {@link Cartesian3} positions
   * using the maximum level of detail for 3D Tilesets in the scene. Returns a promise that is resolved when
   * the query completes. Each position is modified in place. If a position cannot be clamped because no geometry
   * can be sampled at that location, or another error occurs, the element in the array is set to undefined.
   *
   * @param {Cartesian3[]} cartesians The cartesian positions to update with clamped positions.
   * @param {Object[]} [objectsToExclude] A list of primitives, entities, or 3D Tiles features to not clamp to.
   * @param {Number} [width=0.1] Width of the intersection volume in meters.
   * @returns {Promise.<Cartesian3[]>} A promise that resolves to the provided list of positions when the query has completed.
   *
   * @example
   * var cartesians = [
   *     entities[0].position.getValue(Cesium.JulianDate.now()),
   *     entities[1].position.getValue(Cesium.JulianDate.now())
   * ];
   * var promise = viewer.scene.clampToHeightMostDetailed(cartesians);
   * promise.then(function(updatedCartesians) {
   *     entities[0].position = updatedCartesians[0];
   *     entities[1].position = updatedCartesians[1];
   * }
   *
   * @see Scene#clampToHeight
   *
   * @exception {DeveloperError} clampToHeightMostDetailed is only supported in 3D mode.
   * @exception {DeveloperError} clampToHeightMostDetailed requires depth texture support. Check clampToHeightSupported.
   */
  Scene.prototype.clampToHeightMostDetailed = function (
    cartesians,
    objectsToExclude,
    width
  ) {
    return this._picking.clampToHeightMostDetailed(
      this,
      cartesians,
      objectsToExclude,
      width
    );
  };

  /**
   * Transforms a position in cartesian coordinates to canvas coordinates.  This is commonly used to place an
   * HTML element at the same screen position as an object in the scene.
   *
   * @param {Cartesian3} position The position in cartesian coordinates.
   * @param {Cartesian2} [result] An optional object to return the input position transformed to canvas coordinates.
   * @returns {Cartesian2} The modified result parameter or a new Cartesian2 instance if one was not provided.  This may be <code>undefined</code> if the input position is near the center of the ellipsoid.
   *
   * @example
   * // Output the canvas position of longitude/latitude (0, 0) every time the mouse moves.
   * var scene = widget.scene;
   * var ellipsoid = scene.globe.ellipsoid;
   * var position = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
   * var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
   * handler.setInputAction(function(movement) {
   *     console.log(scene.cartesianToCanvasCoordinates(position));
   * }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
   */
  Scene.prototype.cartesianToCanvasCoordinates = function (position, result) {
    return SceneTransforms.wgs84ToWindowCoordinates(this, position, result);
  };

  /**
   * Instantly completes an active transition.
   */
  Scene.prototype.completeMorph = function () {
    this._transitioner.completeMorph();
  };

  /**
   * Asynchronously transitions the scene to 2D.
   * @param {Number} [duration=2.0] The amount of time, in seconds, for transition animations to complete.
   */
  Scene.prototype.morphTo2D = function (duration) {
    var ellipsoid;
    var globe = this.globe;
    if (defined(globe)) {
      ellipsoid = globe.ellipsoid;
    } else {
      ellipsoid = this.mapProjection.ellipsoid;
    }
    duration = defaultValue(duration, 2.0);
    this._transitioner.morphTo2D(duration, ellipsoid);
  };

  /**
   * Asynchronously transitions the scene to Columbus View.
   * @param {Number} [duration=2.0] The amount of time, in seconds, for transition animations to complete.
   */
  Scene.prototype.morphToColumbusView = function (duration) {
    var ellipsoid;
    var globe = this.globe;
    if (defined(globe)) {
      ellipsoid = globe.ellipsoid;
    } else {
      ellipsoid = this.mapProjection.ellipsoid;
    }
    duration = defaultValue(duration, 2.0);
    this._transitioner.morphToColumbusView(duration, ellipsoid);
  };

  /**
   * Asynchronously transitions the scene to 3D.
   * @param {Number} [duration=2.0] The amount of time, in seconds, for transition animations to complete.
   */
  Scene.prototype.morphTo3D = function (duration) {
    var ellipsoid;
    var globe = this.globe;
    if (defined(globe)) {
      ellipsoid = globe.ellipsoid;
    } else {
      ellipsoid = this.mapProjection.ellipsoid;
    }
    duration = defaultValue(duration, 2.0);
    this._transitioner.morphTo3D(duration, ellipsoid);
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Scene#destroy
   */
  Scene.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * scene = scene && scene.destroy();
   *
   * @see Scene#isDestroyed
   */
  Scene.prototype.destroy = function () {
    this._tweens.removeAll();
    this._computeEngine = this._computeEngine && this._computeEngine.destroy();
    this._screenSpaceCameraController =
      this._screenSpaceCameraController &&
      this._screenSpaceCameraController.destroy();
    this._deviceOrientationCameraController =
      this._deviceOrientationCameraController &&
      !this._deviceOrientationCameraController.isDestroyed() &&
      this._deviceOrientationCameraController.destroy();
    this._primitives = this._primitives && this._primitives.destroy();
    this._groundPrimitives =
      this._groundPrimitives && this._groundPrimitives.destroy();
    this._globe = this._globe && this._globe.destroy();
    this.skyBox = this.skyBox && this.skyBox.destroy();
    this.skyAtmosphere = this.skyAtmosphere && this.skyAtmosphere.destroy();
    this._debugSphere = this._debugSphere && this._debugSphere.destroy();
    this.sun = this.sun && this.sun.destroy();
    this._sunPostProcess = this._sunPostProcess && this._sunPostProcess.destroy();
    this._depthPlane = this._depthPlane && this._depthPlane.destroy();
    this._transitioner = this._transitioner && this._transitioner.destroy();
    this._debugFrustumPlanes =
      this._debugFrustumPlanes && this._debugFrustumPlanes.destroy();
    this._brdfLutGenerator =
      this._brdfLutGenerator && this._brdfLutGenerator.destroy();
    this._picking = this._picking && this._picking.destroy();

    this._defaultView = this._defaultView && this._defaultView.destroy();
    this._view = undefined;

    if (this._removeCreditContainer) {
      this._canvas.parentNode.removeChild(this._creditContainer);
    }

    this.postProcessStages =
      this.postProcessStages && this.postProcessStages.destroy();

    this._context = this._context && this._context.destroy();
    this._frameState.creditDisplay =
      this._frameState.creditDisplay && this._frameState.creditDisplay.destroy();

    if (defined(this._performanceDisplay)) {
      this._performanceDisplay =
        this._performanceDisplay && this._performanceDisplay.destroy();
      this._performanceContainer.parentNode.removeChild(
        this._performanceContainer
      );
    }

    this._removeRequestListenerCallback();
    this._removeTaskProcessorListenerCallback();
    for (var i = 0; i < this._removeGlobeCallbacks.length; ++i) {
      this._removeGlobeCallbacks[i]();
    }
    this._removeGlobeCallbacks.length = 0;

    return destroyObject(this);
  };

  /**
   * @license
   * Copyright (c) 2000-2005, Sean O'Neil (s_p_oneil@hotmail.com)
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * * Redistributions of source code must retain the above copyright notice,
   *   this list of conditions and the following disclaimer.
   * * Redistributions in binary form must reproduce the above copyright notice,
   *   this list of conditions and the following disclaimer in the documentation
   *   and/or other materials provided with the distribution.
   * * Neither the name of the project nor the names of its contributors may be
   *   used to endorse or promote products derived from this software without
   *   specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Modifications made by Cesium GS, Inc.
   */
  //This file is automatically rebuilt by the Cesium build process.
  var SkyAtmosphereCommon = "const float Kr = 0.0025;\n\
const float Kr4PI = Kr * 4.0 * czm_pi;\n\
const float Km = 0.0015;\n\
const float Km4PI = Km * 4.0 * czm_pi;\n\
const float ESun = 15.0;\n\
const float KmESun = Km * ESun;\n\
const float KrESun = Kr * ESun;\n\
const vec3 InvWavelength = vec3(\n\
5.60204474633241,\n\
9.473284437923038,\n\
19.643802610477206);\n\
const float rayleighScaleDepth = 0.25;\n\
const int nSamples = 2;\n\
const float fSamples = 2.0;\n\
const float g = -0.95;\n\
const float g2 = g * g;\n\
#ifdef COLOR_CORRECT\n\
uniform vec3 u_hsbShift;\n\
#endif\n\
uniform vec3 u_radiiAndDynamicAtmosphereColor;\n\
float scale(float cosAngle)\n\
{\n\
float x = 1.0 - cosAngle;\n\
return rayleighScaleDepth  * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25))));\n\
}\n\
vec3 getLightDirection(vec3 positionWC)\n\
{\n\
float lightEnum = u_radiiAndDynamicAtmosphereColor.z;\n\
vec3 lightDirection =\n\
positionWC * float(lightEnum == 0.0) +\n\
czm_lightDirectionWC * float(lightEnum == 1.0) +\n\
czm_sunDirectionWC * float(lightEnum == 2.0);\n\
return normalize(lightDirection);\n\
}\n\
void calculateRayScatteringFromSpace(in vec3 positionWC, in vec3 ray, in float innerRadius, in float outerRadius, inout float far, out vec3 start, out float startOffset)\n\
{\n\
float cameraHeight = length(positionWC);\n\
float B = 2.0 * dot(positionWC, ray);\n\
float C = cameraHeight * cameraHeight - outerRadius * outerRadius;\n\
float det = max(0.0, B * B - 4.0 * C);\n\
float near = 0.5 * (-B - sqrt(det));\n\
start = positionWC + ray * near;\n\
far -= near;\n\
float startAngle = dot(ray, start) / outerRadius;\n\
float startDepth = exp(-1.0 / rayleighScaleDepth);\n\
startOffset = startDepth * scale(startAngle);\n\
}\n\
void calculateRayScatteringFromGround(in vec3 positionWC, in vec3 ray, in float atmosphereScale, in float innerRadius, out vec3 start, out float startOffset)\n\
{\n\
float cameraHeight = length(positionWC);\n\
start = positionWC;\n\
float height = length(start);\n\
float depth = exp((atmosphereScale / rayleighScaleDepth ) * (innerRadius - cameraHeight));\n\
float startAngle = dot(ray, start) / height;\n\
startOffset = depth*scale(startAngle);\n\
}\n\
czm_raySegment rayEllipsoidIntersection(czm_ray ray, vec3 inverseRadii)\n\
{\n\
vec3 o = inverseRadii * (czm_inverseView * vec4(ray.origin, 1.0)).xyz;\n\
vec3 d = inverseRadii * (czm_inverseView * vec4(ray.direction, 0.0)).xyz;\n\
float a = dot(d, d);\n\
float b = dot(d, o);\n\
float c = dot(o, o) - 1.0;\n\
float discriminant = b * b - a * c;\n\
if (discriminant < 0.0)\n\
{\n\
return czm_emptyRaySegment;\n\
}\n\
discriminant = sqrt(discriminant);\n\
float t1 = (-b - discriminant) / a;\n\
float t2 = (-b + discriminant) / a;\n\
if (t1 < 0.0 && t2 < 0.0)\n\
{\n\
return czm_emptyRaySegment;\n\
}\n\
if (t1 < 0.0 && t2 >= 0.0)\n\
{\n\
t1 = 0.0;\n\
}\n\
return czm_raySegment(t1, t2);\n\
}\n\
vec3 getAdjustedPosition(vec3 positionWC, float innerRadius)\n\
{\n\
float cameraHeight = czm_eyeHeight + innerRadius;\n\
return normalize(positionWC) * cameraHeight;\n\
}\n\
vec3 getTranslucentPosition(vec3 positionWC, vec3 outerPositionWC, float innerRadius, out bool intersectsEllipsoid)\n\
{\n\
vec3 directionWC = normalize(outerPositionWC - positionWC);\n\
vec3 directionEC = czm_viewRotation * directionWC;\n\
czm_ray viewRay = czm_ray(vec3(0.0), directionEC);\n\
czm_raySegment raySegment = rayEllipsoidIntersection(viewRay, czm_ellipsoidInverseRadii);\n\
intersectsEllipsoid = raySegment.start >= 0.0;\n\
if (intersectsEllipsoid)\n\
{\n\
return positionWC + raySegment.stop * directionWC;\n\
}\n\
return getAdjustedPosition(positionWC, innerRadius);\n\
}\n\
void calculateMieColorAndRayleighColor(vec3 outerPositionWC, out vec3 mieColor, out vec3 rayleighColor)\n\
{\n\
float outerRadius = u_radiiAndDynamicAtmosphereColor.x;\n\
float innerRadius = u_radiiAndDynamicAtmosphereColor.y;\n\
#ifdef GLOBE_TRANSLUCENT\n\
bool intersectsEllipsoid = false;\n\
vec3 startPositionWC = getTranslucentPosition(czm_viewerPositionWC, outerPositionWC, innerRadius, intersectsEllipsoid);\n\
#else\n\
vec3 startPositionWC = getAdjustedPosition(czm_viewerPositionWC, innerRadius);\n\
#endif\n\
vec3 lightDirection = getLightDirection(startPositionWC);\n\
vec3 ray = outerPositionWC - startPositionWC;\n\
float far = length(ray);\n\
ray /= far;\n\
float atmosphereScale = 1.0 / (outerRadius - innerRadius);\n\
vec3 start;\n\
float startOffset;\n\
#ifdef SKY_FROM_SPACE\n\
#ifdef GLOBE_TRANSLUCENT\n\
if (intersectsEllipsoid)\n\
{\n\
calculateRayScatteringFromGround(startPositionWC, ray, atmosphereScale, innerRadius, start, startOffset);\n\
}\n\
else\n\
{\n\
calculateRayScatteringFromSpace(startPositionWC, ray, innerRadius, outerRadius, far, start, startOffset);\n\
}\n\
#else\n\
calculateRayScatteringFromSpace(startPositionWC, ray, innerRadius, outerRadius, far, start, startOffset);\n\
#endif\n\
#else\n\
calculateRayScatteringFromGround(startPositionWC, ray, atmosphereScale, innerRadius, start, startOffset);\n\
#endif\n\
float sampleLength = far / fSamples;\n\
float scaledLength = sampleLength * atmosphereScale;\n\
vec3 sampleRay = ray * sampleLength;\n\
vec3 samplePoint = start + sampleRay * 0.5;\n\
vec3 frontColor = vec3(0.0, 0.0, 0.0);\n\
for (int i = 0; i<nSamples; i++)\n\
{\n\
float height = length(samplePoint);\n\
float depth = exp((atmosphereScale / rayleighScaleDepth ) * (innerRadius - height));\n\
float fLightAngle = dot(lightDirection, samplePoint) / height;\n\
float fCameraAngle = dot(ray, samplePoint) / height;\n\
float fScatter = (startOffset + depth*(scale(fLightAngle) - scale(fCameraAngle)));\n\
vec3 attenuate = exp(-fScatter * (InvWavelength * Kr4PI + Km4PI));\n\
frontColor += attenuate * (depth * scaledLength);\n\
samplePoint += sampleRay;\n\
}\n\
mieColor = frontColor * KmESun;\n\
rayleighColor = frontColor * (InvWavelength * KrESun);\n\
mieColor = min(mieColor, vec3(10000000.0));\n\
rayleighColor = min(rayleighColor, vec3(10000000.0));\n\
}\n\
vec4 calculateFinalColor(vec3 positionWC, vec3 toCamera, vec3 lightDirection, vec3 mieColor, vec3 rayleighColor)\n\
{\n\
float cosAngle = dot(lightDirection, normalize(toCamera)) / length(toCamera);\n\
float rayleighPhase = 0.75 * (1.0 + cosAngle * cosAngle);\n\
float miePhase = 1.5 * ((1.0 - g2) / (2.0 + g2)) * (1.0 + cosAngle * cosAngle) / pow(1.0 + g2 - 2.0 * g * cosAngle, 1.5);\n\
vec3 rgb = rayleighPhase * rayleighColor + miePhase * mieColor;\n\
const float exposure = 2.0;\n\
vec3 rgbExposure = vec3(1.0) - exp(-exposure * rgb);\n\
#ifndef HDR\n\
rgb = rgbExposure;\n\
#endif\n\
#ifdef COLOR_CORRECT\n\
vec3 hsb = czm_RGBToHSB(rgb);\n\
hsb.x += u_hsbShift.x;\n\
hsb.y = clamp(hsb.y + u_hsbShift.y, 0.0, 1.0);\n\
hsb.z = hsb.z > czm_epsilon7 ? hsb.z + u_hsbShift.z : 0.0;\n\
rgb = czm_HSBToRGB(hsb);\n\
#endif\n\
float outerRadius = u_radiiAndDynamicAtmosphereColor.x;\n\
float innerRadius = u_radiiAndDynamicAtmosphereColor.y;\n\
float lightEnum = u_radiiAndDynamicAtmosphereColor.z;\n\
float cameraHeight = czm_eyeHeight + innerRadius;\n\
float atmosphereAlpha = clamp((outerRadius - cameraHeight) / (outerRadius - innerRadius), 0.0, 1.0);\n\
float nightAlpha = (lightEnum != 0.0) ? clamp(dot(normalize(positionWC), lightDirection), 0.0, 1.0) : 1.0;\n\
atmosphereAlpha *= pow(nightAlpha, 0.5);\n\
vec4 finalColor = vec4(rgb, mix(clamp(rgbExposure.b, 0.0, 1.0), 1.0, atmosphereAlpha) * smoothstep(0.0, 1.0, czm_morphTime));\n\
if (mieColor.b > 1.0)\n\
{\n\
float strength = mieColor.b;\n\
float minDistance = outerRadius;\n\
float maxDistance = outerRadius * 3.0;\n\
float maxStrengthLerp = 1.0 - clamp((maxDistance - cameraHeight) / (maxDistance - minDistance), 0.0, 1.0);\n\
float maxStrength = mix(100.0, 10000.0, maxStrengthLerp);\n\
strength = min(strength, maxStrength);\n\
float alpha = 1.0 - (strength / maxStrength);\n\
finalColor.a = alpha;\n\
}\n\
return finalColor;\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var SkyAtmosphereFS = "varying vec3 v_outerPositionWC;\n\
#ifndef PER_FRAGMENT_ATMOSPHERE\n\
varying vec3 v_mieColor;\n\
varying vec3 v_rayleighColor;\n\
#endif\n\
void main (void)\n\
{\n\
vec3 toCamera = czm_viewerPositionWC - v_outerPositionWC;\n\
vec3 lightDirection = getLightDirection(czm_viewerPositionWC);\n\
vec3 mieColor;\n\
vec3 rayleighColor;\n\
#ifdef PER_FRAGMENT_ATMOSPHERE\n\
calculateMieColorAndRayleighColor(v_outerPositionWC, mieColor, rayleighColor);\n\
#else\n\
mieColor = v_mieColor;\n\
rayleighColor = v_rayleighColor;\n\
#endif\n\
gl_FragColor = calculateFinalColor(czm_viewerPositionWC, toCamera, lightDirection, mieColor, rayleighColor);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var SkyAtmosphereVS = "attribute vec4 position;\n\
varying vec3 v_outerPositionWC;\n\
#ifndef PER_FRAGMENT_ATMOSPHERE\n\
varying vec3 v_mieColor;\n\
varying vec3 v_rayleighColor;\n\
#endif\n\
void main(void)\n\
{\n\
vec4 positionWC = czm_model * position;\n\
#ifndef PER_FRAGMENT_ATMOSPHERE\n\
calculateMieColorAndRayleighColor(positionWC.xyz, v_mieColor, v_rayleighColor);\n\
#endif\n\
v_outerPositionWC = positionWC.xyz;\n\
gl_Position = czm_modelViewProjection * position;\n\
}\n\
";

  /**
   * An atmosphere drawn around the limb of the provided ellipsoid.  Based on
   * {@link https://developer.nvidia.com/gpugems/GPUGems2/gpugems2_chapter16.html|Accurate Atmospheric Scattering}
   * in GPU Gems 2.
   * <p>
   * This is only supported in 3D. Atmosphere is faded out when morphing to 2D or Columbus view.
   * </p>
   *
   * @alias SkyAtmosphere
   * @constructor
   *
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid that the atmosphere is drawn around.
   *
   * @example
   * scene.skyAtmosphere = new Cesium.SkyAtmosphere();
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Sky%20Atmosphere.html|Sky atmosphere demo in Sandcastle}
   *
   * @see Scene.skyAtmosphere
   */
  function SkyAtmosphere(ellipsoid) {
    ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);

    /**
     * Determines if the atmosphere is shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = true;

    /**
     * Compute atmosphere per-fragment instead of per-vertex.
     * This produces better looking atmosphere with a slight performance penalty.
     *
     * @type {Boolean}
     * @default false
     */
    this.perFragmentAtmosphere = false;

    this._ellipsoid = ellipsoid;

    var outerEllipsoidScale = 1.025;
    var scaleVector = Cartesian3.multiplyByScalar(
      ellipsoid.radii,
      outerEllipsoidScale,
      new Cartesian3()
    );
    this._scaleMatrix = Matrix4.fromScale(scaleVector);
    this._modelMatrix = new Matrix4();

    this._command = new DrawCommand({
      owner: this,
      modelMatrix: this._modelMatrix,
    });
    this._spSkyFromSpace = undefined;
    this._spSkyFromAtmosphere = undefined;

    this._flags = undefined;

    /**
     * The hue shift to apply to the atmosphere. Defaults to 0.0 (no shift).
     * A hue shift of 1.0 indicates a complete rotation of the hues available.
     * @type {Number}
     * @default 0.0
     */
    this.hueShift = 0.0;

    /**
     * The saturation shift to apply to the atmosphere. Defaults to 0.0 (no shift).
     * A saturation shift of -1.0 is monochrome.
     * @type {Number}
     * @default 0.0
     */
    this.saturationShift = 0.0;

    /**
     * The brightness shift to apply to the atmosphere. Defaults to 0.0 (no shift).
     * A brightness shift of -1.0 is complete darkness, which will let space show through.
     * @type {Number}
     * @default 0.0
     */
    this.brightnessShift = 0.0;

    this._hueSaturationBrightness = new Cartesian3();

    // outer radius, inner radius, dynamic atmosphere color flag
    var radiiAndDynamicAtmosphereColor = new Cartesian3();

    radiiAndDynamicAtmosphereColor.x =
      ellipsoid.maximumRadius * outerEllipsoidScale;
    radiiAndDynamicAtmosphereColor.y = ellipsoid.maximumRadius;

    // Toggles whether the sun position is used. 0 treats the sun as always directly overhead.
    radiiAndDynamicAtmosphereColor.z = 0;

    this._radiiAndDynamicAtmosphereColor = radiiAndDynamicAtmosphereColor;

    var that = this;

    this._command.uniformMap = {
      u_radiiAndDynamicAtmosphereColor: function () {
        return that._radiiAndDynamicAtmosphereColor;
      },
      u_hsbShift: function () {
        that._hueSaturationBrightness.x = that.hueShift;
        that._hueSaturationBrightness.y = that.saturationShift;
        that._hueSaturationBrightness.z = that.brightnessShift;
        return that._hueSaturationBrightness;
      },
    };
  }

  Object.defineProperties(SkyAtmosphere.prototype, {
    /**
     * Gets the ellipsoid the atmosphere is drawn around.
     * @memberof SkyAtmosphere.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
  });

  /**
   * @private
   */
  SkyAtmosphere.prototype.setDynamicAtmosphereColor = function (
    enableLighting,
    useSunDirection
  ) {
    var lightEnum = enableLighting ? (useSunDirection ? 2.0 : 1.0) : 0.0;
    this._radiiAndDynamicAtmosphereColor.z = lightEnum;
  };

  var scratchModelMatrix = new Matrix4();

  /**
   * @private
   */
  SkyAtmosphere.prototype.update = function (frameState, globe) {
    if (!this.show) {
      return undefined;
    }

    var mode = frameState.mode;
    if (mode !== SceneMode$1.SCENE3D && mode !== SceneMode$1.MORPHING) {
      return undefined;
    }

    // The atmosphere is only rendered during the render pass; it is not pickable, it doesn't cast shadows, etc.
    if (!frameState.passes.render) {
      return undefined;
    }

    // Align the ellipsoid geometry so it always faces the same direction as the
    // camera to reduce artifacts when rendering atmosphere per-vertex
    var rotationMatrix = Matrix4.fromRotationTranslation(
      frameState.context.uniformState.inverseViewRotation,
      Cartesian3.ZERO,
      scratchModelMatrix
    );
    var rotationOffsetMatrix = Matrix4.multiplyTransformation(
      rotationMatrix,
      Axis$1.Y_UP_TO_Z_UP,
      scratchModelMatrix
    );
    var modelMatrix = Matrix4.multiply(
      this._scaleMatrix,
      rotationOffsetMatrix,
      scratchModelMatrix
    );
    Matrix4.clone(modelMatrix, this._modelMatrix);

    var context = frameState.context;

    var colorCorrect = hasColorCorrection(this);
    var translucent = frameState.globeTranslucencyState.translucent;
    var perFragmentAtmosphere =
      this.perFragmentAtmosphere || translucent || !defined(globe) || !globe.show;

    var command = this._command;

    if (!defined(command.vertexArray)) {
      var geometry = EllipsoidGeometry.createGeometry(
        new EllipsoidGeometry({
          radii: new Cartesian3(1.0, 1.0, 1.0),
          slicePartitions: 256,
          stackPartitions: 256,
          vertexFormat: VertexFormat.POSITION_ONLY,
        })
      );
      command.vertexArray = VertexArray.fromGeometry({
        context: context,
        geometry: geometry,
        attributeLocations: GeometryPipeline.createAttributeLocations(geometry),
        bufferUsage: BufferUsage$1.STATIC_DRAW,
      });
      command.renderState = RenderState.fromCache({
        cull: {
          enabled: true,
          face: CullFace$1.FRONT,
        },
        blending: BlendingState$1.ALPHA_BLEND,
        depthMask: false,
      });
    }

    var flags = colorCorrect | (perFragmentAtmosphere << 2) | (translucent << 3);

    if (flags !== this._flags) {
      this._flags = flags;

      var defines = [];

      if (colorCorrect) {
        defines.push("COLOR_CORRECT");
      }

      if (perFragmentAtmosphere) {
        defines.push("PER_FRAGMENT_ATMOSPHERE");
      }

      if (translucent) {
        defines.push("GLOBE_TRANSLUCENT");
      }

      var vs = new ShaderSource({
        defines: defines.concat("SKY_FROM_SPACE"),
        sources: [SkyAtmosphereCommon, SkyAtmosphereVS],
      });

      var fs = new ShaderSource({
        defines: defines.concat("SKY_FROM_SPACE"),
        sources: [SkyAtmosphereCommon, SkyAtmosphereFS],
      });

      this._spSkyFromSpace = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: vs,
        fragmentShaderSource: fs,
      });

      vs = new ShaderSource({
        defines: defines.concat("SKY_FROM_ATMOSPHERE"),
        sources: [SkyAtmosphereCommon, SkyAtmosphereVS],
      });

      fs = new ShaderSource({
        defines: defines.concat("SKY_FROM_ATMOSPHERE"),
        sources: [SkyAtmosphereCommon, SkyAtmosphereFS],
      });

      this._spSkyFromAtmosphere = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: vs,
        fragmentShaderSource: fs,
      });
    }

    var cameraPosition = frameState.camera.positionWC;
    var cameraHeight = Cartesian3.magnitude(cameraPosition);

    if (cameraHeight > this._radiiAndDynamicAtmosphereColor.x) {
      // Camera in space
      command.shaderProgram = this._spSkyFromSpace;
    } else {
      // Camera in atmosphere
      command.shaderProgram = this._spSkyFromAtmosphere;
    }

    return command;
  };

  function hasColorCorrection(skyAtmosphere) {
    return !(
      CesiumMath.equalsEpsilon(
        skyAtmosphere.hueShift,
        0.0,
        CesiumMath.EPSILON7
      ) &&
      CesiumMath.equalsEpsilon(
        skyAtmosphere.saturationShift,
        0.0,
        CesiumMath.EPSILON7
      ) &&
      CesiumMath.equalsEpsilon(
        skyAtmosphere.brightnessShift,
        0.0,
        CesiumMath.EPSILON7
      )
    );
  }

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see SkyAtmosphere#destroy
   */
  SkyAtmosphere.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * skyAtmosphere = skyAtmosphere && skyAtmosphere.destroy();
   *
   * @see SkyAtmosphere#isDestroyed
   */
  SkyAtmosphere.prototype.destroy = function () {
    var command = this._command;
    command.vertexArray = command.vertexArray && command.vertexArray.destroy();
    this._spSkyFromSpace = this._spSkyFromSpace && this._spSkyFromSpace.destroy();
    this._spSkyFromAtmosphere =
      this._spSkyFromAtmosphere && this._spSkyFromAtmosphere.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var SkyBoxFS = "uniform samplerCube u_cubeMap;\n\
varying vec3 v_texCoord;\n\
void main()\n\
{\n\
vec4 color = textureCube(u_cubeMap, normalize(v_texCoord));\n\
gl_FragColor = vec4(czm_gammaCorrect(color).rgb, czm_morphTime);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var SkyBoxVS = "attribute vec3 position;\n\
varying vec3 v_texCoord;\n\
void main()\n\
{\n\
vec3 p = czm_viewRotation * (czm_temeToPseudoFixed * (czm_entireFrustum.y * position));\n\
gl_Position = czm_projection * vec4(p, 1.0);\n\
v_texCoord = position.xyz;\n\
}\n\
";

  /**
   * A sky box around the scene to draw stars.  The sky box is defined using the True Equator Mean Equinox (TEME) axes.
   * <p>
   * This is only supported in 3D.  The sky box is faded out when morphing to 2D or Columbus view.  The size of
   * the sky box must not exceed {@link Scene#maximumCubeMapSize}.
   * </p>
   *
   * @alias SkyBox
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Object} [options.sources] The source URL or <code>Image</code> object for each of the six cube map faces.  See the example below.
   * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
   *
   *
   * @example
   * scene.skyBox = new Cesium.SkyBox({
   *   sources : {
   *     positiveX : 'skybox_px.png',
   *     negativeX : 'skybox_nx.png',
   *     positiveY : 'skybox_py.png',
   *     negativeY : 'skybox_ny.png',
   *     positiveZ : 'skybox_pz.png',
   *     negativeZ : 'skybox_nz.png'
   *   }
   * });
   *
   * @see Scene#skyBox
   * @see Transforms.computeTemeToPseudoFixedMatrix
   */
  function SkyBox(options) {
    /**
     * The sources used to create the cube map faces: an object
     * with <code>positiveX</code>, <code>negativeX</code>, <code>positiveY</code>,
     * <code>negativeY</code>, <code>positiveZ</code>, and <code>negativeZ</code> properties.
     * These can be either URLs or <code>Image</code> objects.
     *
     * @type Object
     * @default undefined
     */
    this.sources = options.sources;
    this._sources = undefined;

    /**
     * Determines if the sky box will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    this._command = new DrawCommand({
      modelMatrix: Matrix4.clone(Matrix4.IDENTITY),
      owner: this,
    });
    this._cubeMap = undefined;

    this._attributeLocations = undefined;
    this._useHdr = undefined;
  }

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} this.sources is required and must have positiveX, negativeX, positiveY, negativeY, positiveZ, and negativeZ properties.
   * @exception {DeveloperError} this.sources properties must all be the same type.
   */
  SkyBox.prototype.update = function (frameState, useHdr) {
    var that = this;

    if (!this.show) {
      return undefined;
    }

    if (
      frameState.mode !== SceneMode$1.SCENE3D &&
      frameState.mode !== SceneMode$1.MORPHING
    ) {
      return undefined;
    }

    // The sky box is only rendered during the render pass; it is not pickable, it doesn't cast shadows, etc.
    if (!frameState.passes.render) {
      return undefined;
    }

    var context = frameState.context;

    if (this._sources !== this.sources) {
      this._sources = this.sources;
      var sources = this.sources;

      //>>includeStart('debug', pragmas.debug);
      if (
        !defined(sources.positiveX) ||
        !defined(sources.negativeX) ||
        !defined(sources.positiveY) ||
        !defined(sources.negativeY) ||
        !defined(sources.positiveZ) ||
        !defined(sources.negativeZ)
      ) {
        throw new DeveloperError(
          "this.sources is required and must have positiveX, negativeX, positiveY, negativeY, positiveZ, and negativeZ properties."
        );
      }

      if (
        typeof sources.positiveX !== typeof sources.negativeX ||
        typeof sources.positiveX !== typeof sources.positiveY ||
        typeof sources.positiveX !== typeof sources.negativeY ||
        typeof sources.positiveX !== typeof sources.positiveZ ||
        typeof sources.positiveX !== typeof sources.negativeZ
      ) {
        throw new DeveloperError(
          "this.sources properties must all be the same type."
        );
      }
      //>>includeEnd('debug');

      if (typeof sources.positiveX === "string") {
        // Given urls for cube-map images.  Load them.
        loadCubeMap(context, this._sources).then(function (cubeMap) {
          that._cubeMap = that._cubeMap && that._cubeMap.destroy();
          that._cubeMap = cubeMap;
        });
      } else {
        this._cubeMap = this._cubeMap && this._cubeMap.destroy();
        this._cubeMap = new CubeMap({
          context: context,
          source: sources,
        });
      }
    }

    var command = this._command;

    if (!defined(command.vertexArray)) {
      command.uniformMap = {
        u_cubeMap: function () {
          return that._cubeMap;
        },
      };

      var geometry = BoxGeometry.createGeometry(
        BoxGeometry.fromDimensions({
          dimensions: new Cartesian3(2.0, 2.0, 2.0),
          vertexFormat: VertexFormat.POSITION_ONLY,
        })
      );
      var attributeLocations = (this._attributeLocations = GeometryPipeline.createAttributeLocations(
        geometry
      ));

      command.vertexArray = VertexArray.fromGeometry({
        context: context,
        geometry: geometry,
        attributeLocations: attributeLocations,
        bufferUsage: BufferUsage$1.STATIC_DRAW,
      });

      command.renderState = RenderState.fromCache({
        blending: BlendingState$1.ALPHA_BLEND,
      });
    }

    if (!defined(command.shaderProgram) || this._useHdr !== useHdr) {
      var fs = new ShaderSource({
        defines: [useHdr ? "HDR" : ""],
        sources: [SkyBoxFS],
      });
      command.shaderProgram = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: SkyBoxVS,
        fragmentShaderSource: fs,
        attributeLocations: this._attributeLocations,
      });
      this._useHdr = useHdr;
    }

    if (!defined(this._cubeMap)) {
      return undefined;
    }

    return command;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see SkyBox#destroy
   */
  SkyBox.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * skyBox = skyBox && skyBox.destroy();
   *
   * @see SkyBox#isDestroyed
   */
  SkyBox.prototype.destroy = function () {
    var command = this._command;
    command.vertexArray = command.vertexArray && command.vertexArray.destroy();
    command.shaderProgram =
      command.shaderProgram && command.shaderProgram.destroy();
    this._cubeMap = this._cubeMap && this._cubeMap.destroy();
    return destroyObject(this);
  };

  /**
   * A ParticleEmitter that emits particles within a sphere.
   * Particles will be positioned randomly within the sphere and have initial velocities emanating from the center of the sphere.
   *
   * @alias SphereEmitter
   * @constructor
   *
   * @param {Number} [radius=1.0] The radius of the sphere in meters.
   */
  function SphereEmitter(radius) {
    radius = defaultValue(radius, 1.0);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.number.greaterThan("radius", radius, 0.0);
    //>>includeEnd('debug');

    this._radius = defaultValue(radius, 1.0);
  }

  Object.defineProperties(SphereEmitter.prototype, {
    /**
     * The radius of the sphere in meters.
     * @memberof SphereEmitter.prototype
     * @type {Number}
     * @default 1.0
     */
    radius: {
      get: function () {
        return this._radius;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        Check.typeOf.number.greaterThan("value", value, 0.0);
        //>>includeEnd('debug');
        this._radius = value;
      },
    },
  });

  /**
   * Initializes the given {Particle} by setting it's position and velocity.
   *
   * @private
   * @param {Particle} particle The particle to initialize
   */
  SphereEmitter.prototype.emit = function (particle) {
    var theta = CesiumMath.randomBetween(0.0, CesiumMath.TWO_PI);
    var phi = CesiumMath.randomBetween(0.0, CesiumMath.PI);
    var rad = CesiumMath.randomBetween(0.0, this._radius);

    var x = rad * Math.cos(theta) * Math.sin(phi);
    var y = rad * Math.sin(theta) * Math.sin(phi);
    var z = rad * Math.cos(phi);

    particle.position = Cartesian3.fromElements(x, y, z, particle.position);
    particle.velocity = Cartesian3.normalize(
      particle.position,
      particle.velocity
    );
  };

  /**
   * An expression for a style applied to a {@link Cesium3DTileset}.
   * <p>
   * Derived classes of this interface evaluate expressions in the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}.
   * </p>
   * <p>
   * This type describes an interface and is not intended to be instantiated directly.
   * </p>
   *
   * @alias StyleExpression
   * @constructor
   *
   * @see Expression
   * @see ConditionsExpression
   */
  function StyleExpression() {}

  /**
   * Evaluates the result of an expression, optionally using the provided feature's properties. If the result of
   * the expression in the
   * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
   * is of type <code>Boolean</code>, <code>Number</code>, or <code>String</code>, the corresponding JavaScript
   * primitive type will be returned. If the result is a <code>RegExp</code>, a Javascript <code>RegExp</code>
   * object will be returned. If the result is a <code>Cartesian2</code>, <code>Cartesian3</code>, or <code>Cartesian4</code>,
   * a {@link Cartesian2}, {@link Cartesian3}, or {@link Cartesian4} object will be returned. If the <code>result</code> argument is
   * a {@link Color}, the {@link Cartesian4} value is converted to a {@link Color} and then returned.
   *
   * @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
   * @param {Object} [result] The object onto which to store the result.
   * @returns {Boolean|Number|String|RegExp|Cartesian2|Cartesian3|Cartesian4|Color} The result of evaluating the expression.
   */
  StyleExpression.prototype.evaluate = function (feature, result) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Evaluates the result of a Color expression, optionally using the provided feature's properties.
   * <p>
   * This is equivalent to {@link StyleExpression#evaluate} but always returns a {@link Color} object.
   * </p>
   *
   * @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
   * @param {Color} [result] The object in which to store the result.
   * @returns {Color} The modified result parameter or a new Color instance if one was not provided.
   */
  StyleExpression.prototype.evaluateColor = function (feature, result) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Gets the shader function for this expression.
   * Returns undefined if the shader function can't be generated from this expression.
   *
   * @param {String} functionName Name to give to the generated function.
   * @param {String} propertyNameMap Maps property variable names to shader attribute names.
   * @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
   * @param {String} returnType The return type of the generated function.
   *
   * @returns {String} The shader function.
   *
   * @private
   */
  StyleExpression.prototype.getShaderFunction = function (
    functionName,
    propertyNameMap,
    shaderState,
    returnType
  ) {
    DeveloperError.throwInstantiationError();
  };

  //This file is automatically rebuilt by the Cesium build process.
  var SunFS = "uniform sampler2D u_texture;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
vec4 color = texture2D(u_texture, v_textureCoordinates);\n\
gl_FragColor = czm_gammaCorrect(color);\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var SunTextureFS = "uniform float u_radiusTS;\n\
varying vec2 v_textureCoordinates;\n\
vec2 rotate(vec2 p, vec2 direction)\n\
{\n\
return vec2(p.x * direction.x - p.y * direction.y, p.x * direction.y + p.y * direction.x);\n\
}\n\
vec4 addBurst(vec2 position, vec2 direction, float lengthScalar)\n\
{\n\
vec2 rotatedPosition = rotate(position, direction) * vec2(25.0, 0.75);\n\
float radius = length(rotatedPosition) * lengthScalar;\n\
float burst = 1.0 - smoothstep(0.0, 0.55, radius);\n\
return vec4(burst);\n\
}\n\
void main()\n\
{\n\
float lengthScalar = 2.0 / sqrt(2.0);\n\
vec2 position = v_textureCoordinates - vec2(0.5);\n\
float radius = length(position) * lengthScalar;\n\
float surface = step(radius, u_radiusTS);\n\
vec4 color = vec4(vec2(1.0), surface + 0.2, surface);\n\
float glow = 1.0 - smoothstep(0.0, 0.55, radius);\n\
color.ba += mix(vec2(0.0), vec2(1.0), glow) * 0.75;\n\
vec4 burst = vec4(0.0);\n\
burst += 0.4 * addBurst(position, vec2(0.38942,  0.92106), lengthScalar);\n\
burst += 0.4 * addBurst(position, vec2(0.99235,  0.12348), lengthScalar);\n\
burst += 0.4 * addBurst(position, vec2(0.60327, -0.79754), lengthScalar);\n\
burst += 0.3 * addBurst(position, vec2(0.31457,  0.94924), lengthScalar);\n\
burst += 0.3 * addBurst(position, vec2(0.97931,  0.20239), lengthScalar);\n\
burst += 0.3 * addBurst(position, vec2(0.66507, -0.74678), lengthScalar);\n\
color += clamp(burst, vec4(0.0), vec4(1.0)) * 0.15;\n\
gl_FragColor = clamp(color, vec4(0.0), vec4(1.0));\n\
}\n\
";

  //This file is automatically rebuilt by the Cesium build process.
  var SunVS = "attribute vec2 direction;\n\
uniform float u_size;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
vec4 position;\n\
if (czm_morphTime == 1.0)\n\
{\n\
position = vec4(czm_sunPositionWC, 1.0);\n\
}\n\
else\n\
{\n\
position = vec4(czm_sunPositionColumbusView.zxy, 1.0);\n\
}\n\
vec4 positionEC = czm_view * position;\n\
vec4 positionWC = czm_eyeToWindowCoordinates(positionEC);\n\
vec2 halfSize = vec2(u_size * 0.5);\n\
halfSize *= ((direction * 2.0) - 1.0);\n\
gl_Position = czm_viewportOrthographic * vec4(positionWC.xy + halfSize, -positionWC.z, 1.0);\n\
v_textureCoordinates = direction;\n\
}\n\
";

  /**
   * Draws a sun billboard.
   * <p>This is only supported in 3D and Columbus view.</p>
   *
   * @alias Sun
   * @constructor
   *
   *
   * @example
   * scene.sun = new Cesium.Sun();
   *
   * @see Scene#sun
   */
  function Sun() {
    /**
     * Determines if the sun will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = true;

    this._drawCommand = new DrawCommand({
      primitiveType: PrimitiveType$1.TRIANGLES,
      boundingVolume: new BoundingSphere(),
      owner: this,
    });
    this._commands = {
      drawCommand: this._drawCommand,
      computeCommand: undefined,
    };
    this._boundingVolume = new BoundingSphere();
    this._boundingVolume2D = new BoundingSphere();

    this._texture = undefined;
    this._drawingBufferWidth = undefined;
    this._drawingBufferHeight = undefined;
    this._radiusTS = undefined;
    this._size = undefined;

    this.glowFactor = 1.0;
    this._glowFactorDirty = false;

    this._useHdr = undefined;

    var that = this;
    this._uniformMap = {
      u_texture: function () {
        return that._texture;
      },
      u_size: function () {
        return that._size;
      },
    };
  }

  Object.defineProperties(Sun.prototype, {
    /**
     * Gets or sets a number that controls how "bright" the Sun's lens flare appears
     * to be.  Zero shows just the Sun's disc without any flare.
     * Use larger values for a more pronounced flare around the Sun.
     *
     * @memberof Sun.prototype
     * @type {Number}
     * @default 1.0
     */
    glowFactor: {
      get: function () {
        return this._glowFactor;
      },
      set: function (glowFactor) {
        glowFactor = Math.max(glowFactor, 0.0);
        this._glowFactor = glowFactor;
        this._glowFactorDirty = true;
      },
    },
  });

  var scratchPositionWC = new Cartesian2();
  var scratchLimbWC = new Cartesian2();
  var scratchPositionEC = new Cartesian4();
  var scratchCartesian4$6 = new Cartesian4();

  /**
   * @private
   */
  Sun.prototype.update = function (frameState, passState, useHdr) {
    if (!this.show) {
      return undefined;
    }

    var mode = frameState.mode;
    if (mode === SceneMode$1.SCENE2D || mode === SceneMode$1.MORPHING) {
      return undefined;
    }

    if (!frameState.passes.render) {
      return undefined;
    }

    var context = frameState.context;
    var drawingBufferWidth = passState.viewport.width;
    var drawingBufferHeight = passState.viewport.height;

    if (
      !defined(this._texture) ||
      drawingBufferWidth !== this._drawingBufferWidth ||
      drawingBufferHeight !== this._drawingBufferHeight ||
      this._glowFactorDirty ||
      useHdr !== this._useHdr
    ) {
      this._texture = this._texture && this._texture.destroy();
      this._drawingBufferWidth = drawingBufferWidth;
      this._drawingBufferHeight = drawingBufferHeight;
      this._glowFactorDirty = false;
      this._useHdr = useHdr;

      var size = Math.max(drawingBufferWidth, drawingBufferHeight);
      size = Math.pow(2.0, Math.ceil(Math.log(size) / Math.log(2.0)) - 2.0);

      // The size computed above can be less than 1.0 if size < 4.0. This will probably
      // never happen in practice, but does in the tests. Clamp to 1.0 to prevent WebGL
      // errors in the tests.
      size = Math.max(1.0, size);

      var pixelDatatype = useHdr
        ? context.halfFloatingPointTexture
          ? PixelDatatype$1.HALF_FLOAT
          : PixelDatatype$1.FLOAT
        : PixelDatatype$1.UNSIGNED_BYTE;
      this._texture = new Texture({
        context: context,
        width: size,
        height: size,
        pixelFormat: PixelFormat$1.RGBA,
        pixelDatatype: pixelDatatype,
      });

      this._glowLengthTS = this._glowFactor * 5.0;
      this._radiusTS = (1.0 / (1.0 + 2.0 * this._glowLengthTS)) * 0.5;

      var that = this;
      var uniformMap = {
        u_radiusTS: function () {
          return that._radiusTS;
        },
      };

      this._commands.computeCommand = new ComputeCommand({
        fragmentShaderSource: SunTextureFS,
        outputTexture: this._texture,
        uniformMap: uniformMap,
        persists: false,
        owner: this,
        postExecute: function () {
          that._commands.computeCommand = undefined;
        },
      });
    }

    var drawCommand = this._drawCommand;

    if (!defined(drawCommand.vertexArray)) {
      var attributeLocations = {
        direction: 0,
      };

      var directions = new Uint8Array(4 * 2);
      directions[0] = 0;
      directions[1] = 0;

      directions[2] = 255;
      directions[3] = 0.0;

      directions[4] = 255;
      directions[5] = 255;

      directions[6] = 0.0;
      directions[7] = 255;

      var vertexBuffer = Buffer$1.createVertexBuffer({
        context: context,
        typedArray: directions,
        usage: BufferUsage$1.STATIC_DRAW,
      });
      var attributes = [
        {
          index: attributeLocations.direction,
          vertexBuffer: vertexBuffer,
          componentsPerAttribute: 2,
          normalize: true,
          componentDatatype: ComponentDatatype$1.UNSIGNED_BYTE,
        },
      ];
      // Workaround Internet Explorer 11.0.8 lack of TRIANGLE_FAN
      var indexBuffer = Buffer$1.createIndexBuffer({
        context: context,
        typedArray: new Uint16Array([0, 1, 2, 0, 2, 3]),
        usage: BufferUsage$1.STATIC_DRAW,
        indexDatatype: IndexDatatype$1.UNSIGNED_SHORT,
      });
      drawCommand.vertexArray = new VertexArray({
        context: context,
        attributes: attributes,
        indexBuffer: indexBuffer,
      });

      drawCommand.shaderProgram = ShaderProgram.fromCache({
        context: context,
        vertexShaderSource: SunVS,
        fragmentShaderSource: SunFS,
        attributeLocations: attributeLocations,
      });

      drawCommand.renderState = RenderState.fromCache({
        blending: BlendingState$1.ALPHA_BLEND,
      });
      drawCommand.uniformMap = this._uniformMap;
    }

    var sunPosition = context.uniformState.sunPositionWC;
    var sunPositionCV = context.uniformState.sunPositionColumbusView;

    var boundingVolume = this._boundingVolume;
    var boundingVolume2D = this._boundingVolume2D;

    Cartesian3.clone(sunPosition, boundingVolume.center);
    boundingVolume2D.center.x = sunPositionCV.z;
    boundingVolume2D.center.y = sunPositionCV.x;
    boundingVolume2D.center.z = sunPositionCV.y;

    boundingVolume.radius =
      CesiumMath.SOLAR_RADIUS + CesiumMath.SOLAR_RADIUS * this._glowLengthTS;
    boundingVolume2D.radius = boundingVolume.radius;

    if (mode === SceneMode$1.SCENE3D) {
      BoundingSphere.clone(boundingVolume, drawCommand.boundingVolume);
    } else if (mode === SceneMode$1.COLUMBUS_VIEW) {
      BoundingSphere.clone(boundingVolume2D, drawCommand.boundingVolume);
    }

    var position = SceneTransforms.computeActualWgs84Position(
      frameState,
      sunPosition,
      scratchCartesian4$6
    );

    var dist = Cartesian3.magnitude(
      Cartesian3.subtract(position, frameState.camera.position, scratchCartesian4$6)
    );
    var projMatrix = context.uniformState.projection;

    var positionEC = scratchPositionEC;
    positionEC.x = 0;
    positionEC.y = 0;
    positionEC.z = -dist;
    positionEC.w = 1;

    var positionCC = Matrix4.multiplyByVector(
      projMatrix,
      positionEC,
      scratchCartesian4$6
    );
    var positionWC = SceneTransforms.clipToGLWindowCoordinates(
      passState.viewport,
      positionCC,
      scratchPositionWC
    );

    positionEC.x = CesiumMath.SOLAR_RADIUS;
    var limbCC = Matrix4.multiplyByVector(
      projMatrix,
      positionEC,
      scratchCartesian4$6
    );
    var limbWC = SceneTransforms.clipToGLWindowCoordinates(
      passState.viewport,
      limbCC,
      scratchLimbWC
    );

    this._size = Cartesian2.magnitude(
      Cartesian2.subtract(limbWC, positionWC, scratchCartesian4$6)
    );
    this._size = 2.0 * this._size * (1.0 + 2.0 * this._glowLengthTS);
    this._size = Math.ceil(this._size);

    return this._commands;
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see Sun#destroy
   */
  Sun.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * sun = sun && sun.destroy();
   *
   *  @see Sun#isDestroyed
   */
  Sun.prototype.destroy = function () {
    var command = this._drawCommand;
    command.vertexArray = command.vertexArray && command.vertexArray.destroy();
    command.shaderProgram =
      command.shaderProgram && command.shaderProgram.destroy();

    this._texture = this._texture && this._texture.destroy();

    return destroyObject(this);
  };

  /**
   * Defines a bounding volume for a tile. This type describes an interface
   * and is not intended to be instantiated directly.
   *
   * @alias TileBoundingVolume
   * @constructor
   *
   * @see TileBoundingRegion
   * @see TileBoundingSphere
   * @see TileOrientedBoundingBox
   *
   * @private
   */
  function TileBoundingVolume() {}

  /**
   * The underlying bounding volume.
   *
   * @type {Object}
   * @readonly
   */
  TileBoundingVolume.prototype.boundingVolume = undefined;

  /**
   * The underlying bounding sphere.
   *
   * @type {BoundingSphere}
   * @readonly
   */
  TileBoundingVolume.prototype.boundingSphere = undefined;

  /**
   * Calculates the distance between the tile and the camera.
   *
   * @param {FrameState} frameState The frame state.
   * @return {Number} The distance between the tile and the camera, in meters.
   *                  Returns 0.0 if the camera is inside the tile.
   */
  TileBoundingVolume.prototype.distanceToCamera = function (frameState) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Determines which side of a plane this volume is located.
   *
   * @param {Plane} plane The plane to test against.
   * @returns {Intersect} {@link Intersect.INSIDE} if the entire volume is on the side of the plane
   *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire volume is
   *                      on the opposite side, and {@link Intersect.INTERSECTING} if the volume
   *                      intersects the plane.
   */
  TileBoundingVolume.prototype.intersectPlane = function (plane) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * Creates a debug primitive that shows the outline of the tile bounding
   * volume.
   *
   * @param {Color} color The desired color of the primitive's mesh
   * @return {Primitive}
   */
  TileBoundingVolume.prototype.createDebugVolume = function (color) {
    DeveloperError.throwInstantiationError();
  };

  /**
   * @typedef {Object} TileCoordinatesImageryProvider.ConstructorOptions
   *
   * Initialization options for the TileCoordinatesImageryProvider constructor
   *
   * @property {TilingScheme} [tilingScheme=new GeographicTilingScheme()] The tiling scheme for which to draw tiles.
   * @property {Ellipsoid} [ellipsoid] The ellipsoid.  If the tilingScheme is specified,
   *                    this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
   *                    parameter is specified, the WGS84 ellipsoid is used.
   * @property {Color} [color=Color.YELLOW] The color to draw the tile box and label.
   * @property {Number} [tileWidth=256] The width of the tile for level-of-detail selection purposes.
   * @property {Number} [tileHeight=256] The height of the tile for level-of-detail selection purposes.
   */

  /**
   * An {@link ImageryProvider} that draws a box around every rendered tile in the tiling scheme, and draws
   * a label inside it indicating the X, Y, Level coordinates of the tile.  This is mostly useful for
   * debugging terrain and imagery rendering problems.
   *
   * @alias TileCoordinatesImageryProvider
   * @constructor
   *
   * @param {TileCoordinatesImageryProvider.ConstructorOptions} [options] Object describing initialization options
   */
  function TileCoordinatesImageryProvider(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    this._tilingScheme = defined(options.tilingScheme)
      ? options.tilingScheme
      : new GeographicTilingScheme({ ellipsoid: options.ellipsoid });
    this._color = defaultValue(options.color, Color.YELLOW);
    this._errorEvent = new Event();
    this._tileWidth = defaultValue(options.tileWidth, 256);
    this._tileHeight = defaultValue(options.tileHeight, 256);
    this._readyPromise = when.resolve(true);

    /**
     * The default alpha blending value of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultAlpha = undefined;

    /**
     * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultNightAlpha = undefined;

    /**
     * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
     * 1.0 representing fully opaque.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultDayAlpha = undefined;

    /**
     * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
     * makes the imagery darker while greater than 1.0 makes it brighter.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultBrightness = undefined;

    /**
     * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
     * the contrast while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultContrast = undefined;

    /**
     * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultHue = undefined;

    /**
     * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
     * saturation while greater than 1.0 increases it.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultSaturation = undefined;

    /**
     * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.defaultGamma = undefined;

    /**
     * The default texture minification filter to apply to this provider.
     *
     * @type {TextureMinificationFilter}
     * @default undefined
     */
    this.defaultMinificationFilter = undefined;

    /**
     * The default texture magnification filter to apply to this provider.
     *
     * @type {TextureMagnificationFilter}
     * @default undefined
     */
    this.defaultMagnificationFilter = undefined;
  }

  Object.defineProperties(TileCoordinatesImageryProvider.prototype, {
    /**
     * Gets the proxy used by this provider.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Proxy}
     * @readonly
     */
    proxy: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the width of each tile, in pixels. This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileWidth: {
      get: function () {
        return this._tileWidth;
      },
    },

    /**
     * Gets the height of each tile, in pixels.  This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    tileHeight: {
      get: function () {
        return this._tileHeight;
      },
    },

    /**
     * Gets the maximum level-of-detail that can be requested.  This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Number|undefined}
     * @readonly
     */
    maximumLevel: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the minimum level-of-detail that can be requested.  This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Number}
     * @readonly
     */
    minimumLevel: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets the tiling scheme used by this provider.  This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {TilingScheme}
     * @readonly
     */
    tilingScheme: {
      get: function () {
        return this._tilingScheme;
      },
    },

    /**
     * Gets the rectangle, in radians, of the imagery provided by this instance.  This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Rectangle}
     * @readonly
     */
    rectangle: {
      get: function () {
        return this._tilingScheme.rectangle;
      },
    },

    /**
     * Gets the tile discard policy.  If not undefined, the discard policy is responsible
     * for filtering out "missing" tiles via its shouldDiscardImage function.  If this function
     * returns undefined, no tiles are filtered.  This function should
     * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {TileDiscardPolicy}
     * @readonly
     */
    tileDiscardPolicy: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets an event that is raised when the imagery provider encounters an asynchronous error.  By subscribing
     * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
     * are passed an instance of {@link TileProviderError}.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Event}
     * @readonly
     */
    errorEvent: {
      get: function () {
        return this._errorEvent;
      },
    },

    /**
     * Gets a value indicating whether or not the provider is ready for use.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    ready: {
      get: function () {
        return true;
      },
    },

    /**
     * Gets a promise that resolves to true when the provider is ready for use.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Promise.<Boolean>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise;
      },
    },

    /**
     * Gets the credit to display when this imagery provider is active.  Typically this is used to credit
     * the source of the imagery.  This function should not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Credit}
     * @readonly
     */
    credit: {
      get: function () {
        return undefined;
      },
    },

    /**
     * Gets a value indicating whether or not the images provided by this imagery provider
     * include an alpha channel.  If this property is false, an alpha channel, if present, will
     * be ignored.  If this property is true, any images without an alpha channel will be treated
     * as if their alpha is 1.0 everywhere.  Setting this property to false reduces memory usage
     * and texture upload time.
     * @memberof TileCoordinatesImageryProvider.prototype
     * @type {Boolean}
     * @readonly
     */
    hasAlphaChannel: {
      get: function () {
        return true;
      },
    },
  });

  /**
   * Gets the credits to be displayed when a given tile is displayed.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level;
   * @returns {Credit[]} The credits to be displayed when the tile is displayed.
   *
   * @exception {DeveloperError} <code>getTileCredits</code> must not be called before the imagery provider is ready.
   */
  TileCoordinatesImageryProvider.prototype.getTileCredits = function (
    x,
    y,
    level
  ) {
    return undefined;
  };

  /**
   * Requests the image for a given tile.  This function should
   * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Request} [request] The request object. Intended for internal use only.
   * @returns {Promise.<HTMLImageElement|HTMLCanvasElement>|undefined} A promise for the image that will resolve when the image is available, or
   *          undefined if there are too many active requests to the server, and the request
   *          should be retried later.  The resolved image may be either an
   *          Image or a Canvas DOM object.
   */
  TileCoordinatesImageryProvider.prototype.requestImage = function (
    x,
    y,
    level,
    request
  ) {
    var canvas = document.createElement("canvas");
    canvas.width = 256;
    canvas.height = 256;
    var context = canvas.getContext("2d");

    var cssColor = this._color.toCssColorString();

    context.strokeStyle = cssColor;
    context.lineWidth = 2;
    context.strokeRect(1, 1, 255, 255);

    context.font = "bold 25px Arial";
    context.textAlign = "center";
    context.fillStyle = cssColor;
    context.fillText("L: " + level, 124, 86);
    context.fillText("X: " + x, 124, 136);
    context.fillText("Y: " + y, 124, 186);

    return canvas;
  };

  /**
   * Picking features is not currently supported by this imagery provider, so this function simply returns
   * undefined.
   *
   * @param {Number} x The tile X coordinate.
   * @param {Number} y The tile Y coordinate.
   * @param {Number} level The tile level.
   * @param {Number} longitude The longitude at which to pick features.
   * @param {Number} latitude  The latitude at which to pick features.
   * @return {Promise.<ImageryLayerFeatureInfo[]>|undefined} A promise for the picked features that will resolve when the asynchronous
   *                   picking completes.  The resolved value is an array of {@link ImageryLayerFeatureInfo}
   *                   instances.  The array may be empty if no features are found at the given location.
   *                   It may also be undefined if picking is not supported.
   */
  TileCoordinatesImageryProvider.prototype.pickFeatures = function (
    x,
    y,
    level,
    longitude,
    latitude
  ) {
    return undefined;
  };

  /**
   * A policy for discarding tile images according to some criteria.  This type describes an
   * interface and is not intended to be instantiated directly.
   *
   * @alias TileDiscardPolicy
   * @constructor
   *
   * @see DiscardMissingTileImagePolicy
   * @see NeverTileDiscardPolicy
   */
  function TileDiscardPolicy(options) {
    DeveloperError.throwInstantiationError();
  }

  /**
   * Determines if the discard policy is ready to process images.
   * @function
   *
   * @returns {Boolean} True if the discard policy is ready to process images; otherwise, false.
   */
  TileDiscardPolicy.prototype.isReady = DeveloperError.throwInstantiationError;

  /**
   * Given a tile image, decide whether to discard that image.
   * @function
   *
   * @param {HTMLImageElement} image An image to test.
   * @returns {Boolean} True if the image should be discarded; otherwise, false.
   */
  TileDiscardPolicy.prototype.shouldDiscardImage =
    DeveloperError.throwInstantiationError;

  /**
   * @private
   */
  var TileState = {
    START: 0,
    LOADING: 1,
    READY: 2,
    UPSAMPLED_ONLY: 3,
  };
  var TileState$1 = Object.freeze(TileState);

  /**
   * Provides playback of time-dynamic point cloud data.
   * <p>
   * Point cloud frames are prefetched in intervals determined by the average frame load time and the current clock speed.
   * If intermediate frames cannot be loaded in time to meet playback speed, they will be skipped. If frames are sufficiently
   * small or the clock is sufficiently slow then no frames will be skipped.
   * </p>
   *
   * @alias TimeDynamicPointCloud
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Clock} options.clock A {@link Clock} instance that is used when determining the value for the time dimension.
   * @param {TimeIntervalCollection} options.intervals A {@link TimeIntervalCollection} with its data property being an object containing a <code>uri</code> to a 3D Tiles Point Cloud tile and an optional <code>transform</code>.
   * @param {Boolean} [options.show=true] Determines if the point cloud will be shown.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] A 4x4 transformation matrix that transforms the point cloud.
   * @param {ShadowMode} [options.shadows=ShadowMode.ENABLED] Determines whether the point cloud casts or receives shadows from light sources.
   * @param {Number} [options.maximumMemoryUsage=256] The maximum amount of memory in MB that can be used by the point cloud.
   * @param {Object} [options.shading] Options for constructing a {@link PointCloudShading} object to control point attenuation and eye dome lighting.
   * @param {Cesium3DTileStyle} [options.style] The style, defined using the {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}, applied to each point in the point cloud.
   * @param {ClippingPlaneCollection} [options.clippingPlanes] The {@link ClippingPlaneCollection} used to selectively disable rendering the point cloud.
   */
  function TimeDynamicPointCloud(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("options.clock", options.clock);
    Check.typeOf.object("options.intervals", options.intervals);
    //>>includeEnd('debug');

    /**
     * Determines if the point cloud will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = defaultValue(options.show, true);

    /**
     * A 4x4 transformation matrix that transforms the point cloud.
     *
     * @type {Matrix4}
     * @default Matrix4.IDENTITY
     */
    this.modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );

    /**
     * Determines whether the point cloud casts or receives shadows from light sources.
     * <p>
     * Enabling shadows has a performance impact. A point cloud that casts shadows must be rendered twice, once from the camera and again from the light's point of view.
     * </p>
     * <p>
     * Shadows are rendered only when {@link Viewer#shadows} is <code>true</code>.
     * </p>
     *
     * @type {ShadowMode}
     * @default ShadowMode.ENABLED
     */
    this.shadows = defaultValue(options.shadows, ShadowMode$1.ENABLED);

    /**
     * The maximum amount of GPU memory (in MB) that may be used to cache point cloud frames.
     * <p>
     * Frames that are not being loaded or rendered are unloaded to enforce this.
     * </p>
     * <p>
     * If decreasing this value results in unloading tiles, the tiles are unloaded the next frame.
     * </p>
     *
     * @type {Number}
     * @default 256
     *
     * @see TimeDynamicPointCloud#totalMemoryUsageInBytes
     */
    this.maximumMemoryUsage = defaultValue(options.maximumMemoryUsage, 256);

    /**
     * Options for controlling point size based on geometric error and eye dome lighting.
     * @type {PointCloudShading}
     */
    this.shading = new PointCloudShading(options.shading);

    /**
     * The style, defined using the
     * {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language},
     * applied to each point in the point cloud.
     * <p>
     * Assign <code>undefined</code> to remove the style, which will restore the visual
     * appearance of the point cloud to its default when no style was applied.
     * </p>
     *
     * @type {Cesium3DTileStyle}
     *
     * @example
     * pointCloud.style = new Cesium.Cesium3DTileStyle({
     *    color : {
     *        conditions : [
     *            ['${Classification} === 0', 'color("purple", 0.5)'],
     *            ['${Classification} === 1', 'color("red")'],
     *            ['true', '${COLOR}']
     *        ]
     *    },
     *    show : '${Classification} !== 2'
     * });
     *
     * @see {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
     */
    this.style = options.style;

    /**
     * The event fired to indicate that a frame failed to load. A frame may fail to load if the
     * request for its uri fails or processing fails due to invalid content.
     * <p>
     * If there are no event listeners, error messages will be logged to the console.
     * </p>
     * <p>
     * The error object passed to the listener contains two properties:
     * <ul>
     * <li><code>uri</code>: the uri of the failed frame.</li>
     * <li><code>message</code>: the error message.</li>
     * </ul>
     *
     * @type {Event}
     * @default new Event()
     *
     * @example
     * pointCloud.frameFailed.addEventListener(function(error) {
     *     console.log('An error occurred loading frame: ' + error.uri);
     *     console.log('Error: ' + error.message);
     * });
     */
    this.frameFailed = new Event();

    /**
     * The event fired to indicate that a new frame was rendered.
     * <p>
     * The time dynamic point cloud {@link TimeDynamicPointCloud} is passed to the event listener.
     * </p>
     * @type {Event}
     * @default new Event()
     *
     * @example
     * pointCloud.frameChanged.addEventListener(function(timeDynamicPointCloud) {
     *     viewer.camera.viewBoundingSphere(timeDynamicPointCloud.boundingSphere);
     * });
     */
    this.frameChanged = new Event();

    this._clock = options.clock;
    this._intervals = options.intervals;
    this._clippingPlanes = undefined;
    this.clippingPlanes = options.clippingPlanes; // Call setter
    this._pointCloudEyeDomeLighting = new PointCloudEyeDomeLighting();
    this._loadTimestamp = undefined;
    this._clippingPlanesState = 0;
    this._styleDirty = false;
    this._pickId = undefined;
    this._totalMemoryUsageInBytes = 0;
    this._frames = [];
    this._previousInterval = undefined;
    this._nextInterval = undefined;
    this._lastRenderedFrame = undefined;
    this._clockMultiplier = 0.0;
    this._readyPromise = when.defer();

    // For calculating average load time of the last N frames
    this._runningSum = 0.0;
    this._runningLength = 0;
    this._runningIndex = 0;
    this._runningSamples = arrayFill(new Array(5), 0.0);
    this._runningAverage = 0.0;
  }

  Object.defineProperties(TimeDynamicPointCloud.prototype, {
    /**
     * The {@link ClippingPlaneCollection} used to selectively disable rendering the point cloud.
     *
     * @memberof TimeDynamicPointCloud.prototype
     *
     * @type {ClippingPlaneCollection}
     */
    clippingPlanes: {
      get: function () {
        return this._clippingPlanes;
      },
      set: function (value) {
        ClippingPlaneCollection.setOwner(value, this, "_clippingPlanes");
      },
    },

    /**
     * The total amount of GPU memory in bytes used by the point cloud.
     *
     * @memberof TimeDynamicPointCloud.prototype
     *
     * @type {Number}
     * @readonly
     *
     * @see TimeDynamicPointCloud#maximumMemoryUsage
     */
    totalMemoryUsageInBytes: {
      get: function () {
        return this._totalMemoryUsageInBytes;
      },
    },

    /**
     * The bounding sphere of the frame being rendered. Returns <code>undefined</code> if no frame is being rendered.
     *
     * @memberof TimeDynamicPointCloud.prototype
     *
     * @type {BoundingSphere}
     * @readonly
     */
    boundingSphere: {
      get: function () {
        if (defined(this._lastRenderedFrame)) {
          return this._lastRenderedFrame.pointCloud.boundingSphere;
        }
        return undefined;
      },
    },

    /**
     * Gets the promise that will be resolved when the point cloud renders a frame for the first time.
     *
     * @memberof TimeDynamicPointCloud.prototype
     *
     * @type {Promise.<TimeDynamicPointCloud>}
     * @readonly
     */
    readyPromise: {
      get: function () {
        return this._readyPromise.promise;
      },
    },
  });

  function getFragmentShaderLoaded$1(fs) {
    return "uniform vec4 czm_pickColor;\n" + fs;
  }

  function getUniformMapLoaded$1(stream) {
    return function (uniformMap) {
      return combine(uniformMap, {
        czm_pickColor: function () {
          return stream._pickId.color;
        },
      });
    };
  }

  function getPickIdLoaded$1() {
    return "czm_pickColor";
  }

  /**
   * Marks the point cloud's {@link TimeDynamicPointCloud#style} as dirty, which forces all
   * points to re-evaluate the style in the next frame.
   */
  TimeDynamicPointCloud.prototype.makeStyleDirty = function () {
    this._styleDirty = true;
  };

  /**
   * Exposed for testing.
   *
   * @private
   */
  TimeDynamicPointCloud.prototype._getAverageLoadTime = function () {
    if (this._runningLength === 0) {
      // Before any frames have loaded make a best guess about the average load time
      return 0.05;
    }
    return this._runningAverage;
  };

  var scratchDate$1 = new JulianDate();

  function getClockMultiplier(that) {
    var clock = that._clock;
    var isAnimating = clock.canAnimate && clock.shouldAnimate;
    var multiplier = clock.multiplier;
    return isAnimating ? multiplier : 0.0;
  }

  function getIntervalIndex(that, interval) {
    return that._intervals.indexOf(interval.start);
  }

  function getNextInterval(that, currentInterval) {
    var intervals = that._intervals;
    var clock = that._clock;
    var multiplier = getClockMultiplier(that);

    if (multiplier === 0.0) {
      return undefined;
    }

    var averageLoadTime = that._getAverageLoadTime();
    var time = JulianDate.addSeconds(
      clock.currentTime,
      averageLoadTime * multiplier,
      scratchDate$1
    );
    var index = intervals.indexOf(time);

    var currentIndex = getIntervalIndex(that, currentInterval);
    if (index === currentIndex) {
      if (multiplier >= 0) {
        ++index;
      } else {
        --index;
      }
    }

    // Returns undefined if not in range
    return intervals.get(index);
  }

  function getCurrentInterval(that) {
    var intervals = that._intervals;
    var clock = that._clock;
    var time = clock.currentTime;
    var index = intervals.indexOf(time);

    // Returns undefined if not in range
    return intervals.get(index);
  }

  function reachedInterval(that, currentInterval, nextInterval) {
    var multiplier = getClockMultiplier(that);
    var currentIndex = getIntervalIndex(that, currentInterval);
    var nextIndex = getIntervalIndex(that, nextInterval);

    if (multiplier >= 0) {
      return currentIndex >= nextIndex;
    }
    return currentIndex <= nextIndex;
  }

  function handleFrameFailure(that, uri) {
    return function (error) {
      var message = defined(error.message) ? error.message : error.toString();
      if (that.frameFailed.numberOfListeners > 0) {
        that.frameFailed.raiseEvent({
          uri: uri,
          message: message,
        });
      } else {
        console.log("A frame failed to load: " + uri);
        console.log("Error: " + message);
      }
    };
  }

  function requestFrame(that, interval, frameState) {
    var index = getIntervalIndex(that, interval);
    var frames = that._frames;
    var frame = frames[index];
    if (!defined(frame)) {
      var transformArray = interval.data.transform;
      var transform = defined(transformArray)
        ? Matrix4.fromArray(transformArray)
        : undefined;
      var uri = interval.data.uri;
      frame = {
        pointCloud: undefined,
        transform: transform,
        timestamp: getTimestamp$1(),
        sequential: true,
        ready: false,
        touchedFrameNumber: frameState.frameNumber,
      };
      frames[index] = frame;
      Resource.fetchArrayBuffer({
        url: uri,
      })
        .then(function (arrayBuffer) {
          // PERFORMANCE_IDEA: share a memory pool, render states, shaders, and other resources among all
          // frames. Each frame just needs an index/offset into the pool.
          frame.pointCloud = new PointCloud({
            arrayBuffer: arrayBuffer,
            cull: true,
            fragmentShaderLoaded: getFragmentShaderLoaded$1,
            uniformMapLoaded: getUniformMapLoaded$1(that),
            pickIdLoaded: getPickIdLoaded$1,
          });
          return frame.pointCloud.readyPromise;
        })
        .otherwise(handleFrameFailure(that, uri));
    }
    return frame;
  }

  function updateAverageLoadTime(that, loadTime) {
    that._runningSum += loadTime;
    that._runningSum -= that._runningSamples[that._runningIndex];
    that._runningSamples[that._runningIndex] = loadTime;
    that._runningLength = Math.min(
      that._runningLength + 1,
      that._runningSamples.length
    );
    that._runningIndex = (that._runningIndex + 1) % that._runningSamples.length;
    that._runningAverage = that._runningSum / that._runningLength;
  }

  function prepareFrame(that, frame, updateState, frameState) {
    if (frame.touchedFrameNumber < frameState.frameNumber - 1) {
      // If this frame was not loaded in sequential updates then it can't be used it for calculating the average load time.
      // For example: selecting a frame on the timeline, selecting another frame before the request finishes, then selecting this frame later.
      frame.sequential = false;
    }

    var pointCloud = frame.pointCloud;

    if (defined(pointCloud) && !frame.ready) {
      // Call update to prepare renderer resources. Don't render anything yet.
      var commandList = frameState.commandList;
      var lengthBeforeUpdate = commandList.length;
      renderFrame(that, frame, updateState, frameState);

      if (pointCloud.ready) {
        // Point cloud became ready this update
        frame.ready = true;
        that._totalMemoryUsageInBytes += pointCloud.geometryByteLength;
        commandList.length = lengthBeforeUpdate; // Don't allow preparing frame to insert commands.
        if (frame.sequential) {
          // Update the values used to calculate average load time
          var loadTime = (getTimestamp$1() - frame.timestamp) / 1000.0;
          updateAverageLoadTime(that, loadTime);
        }
      }
    }

    frame.touchedFrameNumber = frameState.frameNumber;
  }

  var scratchModelMatrix$1 = new Matrix4();

  function getGeometricError$1(that, pointCloud) {
    var shading = that.shading;
    if (defined(shading) && defined(shading.baseResolution)) {
      return shading.baseResolution;
    } else if (defined(pointCloud.boundingSphere)) {
      return CesiumMath.cbrt(
        pointCloud.boundingSphere.volume() / pointCloud.pointsLength
      );
    }
    return 0.0;
  }

  function getMaximumAttenuation(that) {
    var shading = that.shading;
    if (defined(shading) && defined(shading.maximumAttenuation)) {
      return shading.maximumAttenuation;
    }

    // Return a hardcoded maximum attenuation. For a tileset this would instead be the maximum screen space error.
    return 10.0;
  }

  var defaultShading$1 = new PointCloudShading();

  function renderFrame(that, frame, updateState, frameState) {
    var shading = defaultValue(that.shading, defaultShading$1);
    var pointCloud = frame.pointCloud;
    var transform = defaultValue(frame.transform, Matrix4.IDENTITY);
    pointCloud.modelMatrix = Matrix4.multiplyTransformation(
      that.modelMatrix,
      transform,
      scratchModelMatrix$1
    );
    pointCloud.style = that.style;
    pointCloud.time = updateState.timeSinceLoad;
    pointCloud.shadows = that.shadows;
    pointCloud.clippingPlanes = that._clippingPlanes;
    pointCloud.isClipped = updateState.isClipped;
    pointCloud.attenuation = shading.attenuation;
    pointCloud.backFaceCulling = shading.backFaceCulling;
    pointCloud.normalShading = shading.normalShading;
    pointCloud.geometricError = getGeometricError$1(that, pointCloud);
    pointCloud.geometricErrorScale = shading.geometricErrorScale;
    pointCloud.maximumAttenuation = getMaximumAttenuation(that);

    pointCloud.update(frameState);
    frame.touchedFrameNumber = frameState.frameNumber;
  }

  function loadFrame(that, interval, updateState, frameState) {
    var frame = requestFrame(that, interval, frameState);
    prepareFrame(that, frame, updateState, frameState);
  }

  function getUnloadCondition(frameState) {
    return function (frame) {
      // Unload all frames that aren't currently being loaded or rendered
      return frame.touchedFrameNumber < frameState.frameNumber;
    };
  }

  function unloadFrames(that, unloadCondition) {
    var frames = that._frames;
    var length = frames.length;
    for (var i = 0; i < length; ++i) {
      var frame = frames[i];
      if (defined(frame)) {
        if (!defined(unloadCondition) || unloadCondition(frame)) {
          var pointCloud = frame.pointCloud;
          if (frame.ready) {
            that._totalMemoryUsageInBytes -= pointCloud.geometryByteLength;
          }
          if (defined(pointCloud)) {
            pointCloud.destroy();
          }
          if (frame === that._lastRenderedFrame) {
            that._lastRenderedFrame = undefined;
          }
          frames[i] = undefined;
        }
      }
    }
  }

  function getFrame(that, interval) {
    var index = getIntervalIndex(that, interval);
    var frame = that._frames[index];
    if (defined(frame) && frame.ready) {
      return frame;
    }
  }

  function updateInterval(that, interval, frame, updateState, frameState) {
    if (defined(frame)) {
      if (frame.ready) {
        return true;
      }
      loadFrame(that, interval, updateState, frameState);
      return frame.ready;
    }
    return false;
  }

  function getNearestReadyInterval(
    that,
    previousInterval,
    currentInterval,
    updateState,
    frameState
  ) {
    var i;
    var interval;
    var frame;
    var intervals = that._intervals;
    var frames = that._frames;
    var currentIndex = getIntervalIndex(that, currentInterval);
    var previousIndex = getIntervalIndex(that, previousInterval);

    if (currentIndex >= previousIndex) {
      // look backwards
      for (i = currentIndex; i >= previousIndex; --i) {
        interval = intervals.get(i);
        frame = frames[i];
        if (updateInterval(that, interval, frame, updateState, frameState)) {
          return interval;
        }
      }
    } else {
      // look forwards
      for (i = currentIndex; i <= previousIndex; ++i) {
        interval = intervals.get(i);
        frame = frames[i];
        if (updateInterval(that, interval, frame, updateState, frameState)) {
          return interval;
        }
      }
    }

    // If no intervals are ready return the previous interval
    return previousInterval;
  }

  function setFramesDirty(that, clippingPlanesDirty, styleDirty) {
    var frames = that._frames;
    var framesLength = frames.length;
    for (var i = 0; i < framesLength; ++i) {
      var frame = frames[i];
      if (defined(frame) && defined(frame.pointCloud)) {
        frame.pointCloud.clippingPlanesDirty = clippingPlanesDirty;
        frame.pointCloud.styleDirty = styleDirty;
      }
    }
  }

  var updateState = {
    timeSinceLoad: 0,
    isClipped: false,
    clippingPlanesDirty: false,
  };

  /**
   * @private
   */
  TimeDynamicPointCloud.prototype.update = function (frameState) {
    if (frameState.mode === SceneMode$1.MORPHING) {
      return;
    }

    if (!this.show) {
      return;
    }

    if (!defined(this._pickId)) {
      this._pickId = frameState.context.createPickId({
        primitive: this,
      });
    }

    if (!defined(this._loadTimestamp)) {
      this._loadTimestamp = JulianDate.clone(frameState.time);
    }

    // For styling
    var timeSinceLoad = Math.max(
      JulianDate.secondsDifference(frameState.time, this._loadTimestamp) * 1000,
      0.0
    );

    // Update clipping planes
    var clippingPlanes = this._clippingPlanes;
    var clippingPlanesState = 0;
    var clippingPlanesDirty = false;
    var isClipped = defined(clippingPlanes) && clippingPlanes.enabled;

    if (isClipped) {
      clippingPlanes.update(frameState);
      clippingPlanesState = clippingPlanes.clippingPlanesState;
    }

    if (this._clippingPlanesState !== clippingPlanesState) {
      this._clippingPlanesState = clippingPlanesState;
      clippingPlanesDirty = true;
    }

    var styleDirty = this._styleDirty;
    this._styleDirty = false;

    if (clippingPlanesDirty || styleDirty) {
      setFramesDirty(this, clippingPlanesDirty, styleDirty);
    }

    updateState.timeSinceLoad = timeSinceLoad;
    updateState.isClipped = isClipped;

    var shading = this.shading;
    var eyeDomeLighting = this._pointCloudEyeDomeLighting;

    var commandList = frameState.commandList;
    var lengthBeforeUpdate = commandList.length;

    var previousInterval = this._previousInterval;
    var nextInterval = this._nextInterval;
    var currentInterval = getCurrentInterval(this);

    if (!defined(currentInterval)) {
      return;
    }

    var clockMultiplierChanged = false;
    var clockMultiplier = getClockMultiplier(this);
    var clockPaused = clockMultiplier === 0;
    if (clockMultiplier !== this._clockMultiplier) {
      clockMultiplierChanged = true;
      this._clockMultiplier = clockMultiplier;
    }

    if (!defined(previousInterval) || clockPaused) {
      previousInterval = currentInterval;
    }

    if (
      !defined(nextInterval) ||
      clockMultiplierChanged ||
      reachedInterval(this, currentInterval, nextInterval)
    ) {
      nextInterval = getNextInterval(this, currentInterval);
    }

    previousInterval = getNearestReadyInterval(
      this,
      previousInterval,
      currentInterval,
      updateState,
      frameState
    );
    var frame = getFrame(this, previousInterval);

    if (!defined(frame)) {
      // The frame is not ready to render. This can happen when the simulation starts or when scrubbing the timeline
      // to a frame that hasn't loaded yet. Just render the last rendered frame in its place until it finishes loading.
      loadFrame(this, previousInterval, updateState, frameState);
      frame = this._lastRenderedFrame;
    }

    if (defined(frame)) {
      renderFrame(this, frame, updateState, frameState);
    }

    if (defined(nextInterval)) {
      // Start loading the next frame
      loadFrame(this, nextInterval, updateState, frameState);
    }

    var that = this;
    if (defined(frame) && !defined(this._lastRenderedFrame)) {
      frameState.afterRender.push(function () {
        that._readyPromise.resolve(that);
      });
    }

    if (defined(frame) && frame !== this._lastRenderedFrame) {
      if (that.frameChanged.numberOfListeners > 0) {
        frameState.afterRender.push(function () {
          that.frameChanged.raiseEvent(that);
        });
      }
    }

    this._previousInterval = previousInterval;
    this._nextInterval = nextInterval;
    this._lastRenderedFrame = frame;

    var totalMemoryUsageInBytes = this._totalMemoryUsageInBytes;
    var maximumMemoryUsageInBytes = this.maximumMemoryUsage * 1024 * 1024;

    if (totalMemoryUsageInBytes > maximumMemoryUsageInBytes) {
      unloadFrames(this, getUnloadCondition(frameState));
    }

    var lengthAfterUpdate = commandList.length;
    var addedCommandsLength = lengthAfterUpdate - lengthBeforeUpdate;

    if (
      defined(shading) &&
      shading.attenuation &&
      shading.eyeDomeLighting &&
      addedCommandsLength > 0
    ) {
      eyeDomeLighting.update(
        frameState,
        lengthBeforeUpdate,
        shading,
        this.boundingSphere
      );
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
   *
   * @see TimeDynamicPointCloud#destroy
   */
  TimeDynamicPointCloud.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   * @example
   * pointCloud = pointCloud && pointCloud.destroy();
   *
   * @see TimeDynamicPointCloud#isDestroyed
   */
  TimeDynamicPointCloud.prototype.destroy = function () {
    unloadFrames(this);
    this._clippingPlanes = this._clippingPlanes && this._clippingPlanes.destroy();
    this._pickId = this._pickId && this._pickId.destroy();
    return destroyObject(this);
  };

  //This file is automatically rebuilt by the Cesium build process.
  var ViewportQuadFS = "varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
czm_materialInput materialInput;\n\
materialInput.s = v_textureCoordinates.s;\n\
materialInput.st = v_textureCoordinates;\n\
materialInput.str = vec3(v_textureCoordinates, 0.0);\n\
materialInput.normalEC = vec3(0.0, 0.0, -1.0);\n\
czm_material material = czm_getMaterial(materialInput);\n\
gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);\n\
}\n\
";

  /**
   * A viewport aligned quad.
   *
   * @alias ViewportQuad
   * @constructor
   *
   * @param {BoundingRectangle} [rectangle] The {@link BoundingRectangle} defining the quad's position within the viewport.
   * @param {Material} [material] The {@link Material} defining the surface appearance of the viewport quad.
   *
   * @example
   * var viewportQuad = new Cesium.ViewportQuad(new Cesium.BoundingRectangle(0, 0, 80, 40));
   * viewportQuad.material.uniforms.color = new Cesium.Color(1.0, 0.0, 0.0, 1.0);
   */
  function ViewportQuad(rectangle, material) {
    /**
     * Determines if the viewport quad primitive will be shown.
     *
     * @type {Boolean}
     * @default true
     */
    this.show = true;

    if (!defined(rectangle)) {
      rectangle = new BoundingRectangle();
    }

    /**
     * The BoundingRectangle defining the quad's position within the viewport.
     *
     * @type {BoundingRectangle}
     *
     * @example
     * viewportQuad.rectangle = new Cesium.BoundingRectangle(0, 0, 80, 40);
     */
    this.rectangle = BoundingRectangle.clone(rectangle);

    if (!defined(material)) {
      material = Material.fromType(Material.ColorType, {
        color: new Color(1.0, 1.0, 1.0, 1.0),
      });
    }

    /**
     * The surface appearance of the viewport quad.  This can be one of several built-in {@link Material} objects or a custom material, scripted with
     * {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}.
     * <p>
     * The default material is <code>Material.ColorType</code>.
     * </p>
     *
     * @type Material
     *
     * @example
     * // 1. Change the color of the default material to yellow
     * viewportQuad.material.uniforms.color = new Cesium.Color(1.0, 1.0, 0.0, 1.0);
     *
     * // 2. Change material to horizontal stripes
     * viewportQuad.material = Cesium.Material.fromType(Cesium.Material.StripeType);
     *
     * @see {@link https://github.com/CesiumGS/cesium/wiki/Fabric|Fabric}
     */
    this.material = material;
    this._material = undefined;

    this._overlayCommand = undefined;
    this._rs = undefined;
  }

  /**
   * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
   * get the draw commands needed to render this primitive.
   * <p>
   * Do not call this function directly.  This is documented just to
   * list the exceptions that may be propagated when the scene is rendered:
   * </p>
   *
   * @exception {DeveloperError} this.material must be defined.
   * @exception {DeveloperError} this.rectangle must be defined.
   */
  ViewportQuad.prototype.update = function (frameState) {
    if (!this.show) {
      return;
    }

    //>>includeStart('debug', pragmas.debug);
    if (!defined(this.material)) {
      throw new DeveloperError("this.material must be defined.");
    }
    if (!defined(this.rectangle)) {
      throw new DeveloperError("this.rectangle must be defined.");
    }
    //>>includeEnd('debug');

    var rs = this._rs;
    if (!defined(rs) || !BoundingRectangle.equals(rs.viewport, this.rectangle)) {
      this._rs = RenderState.fromCache({
        blending: BlendingState$1.ALPHA_BLEND,
        viewport: this.rectangle,
      });
    }

    var pass = frameState.passes;
    if (pass.render) {
      var context = frameState.context;

      if (this._material !== this.material || !defined(this._overlayCommand)) {
        // Recompile shader when material changes
        this._material = this.material;

        if (defined(this._overlayCommand)) {
          this._overlayCommand.shaderProgram.destroy();
        }

        var fs = new ShaderSource({
          sources: [this._material.shaderSource, ViewportQuadFS],
        });
        this._overlayCommand = context.createViewportQuadCommand(fs, {
          renderState: this._rs,
          uniformMap: this._material._uniforms,
          owner: this,
        });
        this._overlayCommand.pass = Pass$1.OVERLAY;
      }

      this._material.update(context);

      this._overlayCommand.uniformMap = this._material._uniforms;
      frameState.commandList.push(this._overlayCommand);
    }
  };

  /**
   * Returns true if this object was destroyed; otherwise, false.
   * <br /><br />
   * If this object was destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
   *
   * @returns {Boolean} True if this object was destroyed; otherwise, false.
   *
   * @see ViewportQuad#destroy
   */
  ViewportQuad.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
   * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
   * <br /><br />
   * Once an object is destroyed, it should not be used; calling any function other than
   * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
   * assign the return value (<code>undefined</code>) to the object as done in the example.
   *
   * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
   *
   *
   * @example
   * quad = quad && quad.destroy();
   *
   * @see ViewportQuad#isDestroyed
   */
  ViewportQuad.prototype.destroy = function () {
    if (defined(this._overlayCommand)) {
      this._overlayCommand.shaderProgram =
        this._overlayCommand.shaderProgram &&
        this._overlayCommand.shaderProgram.destroy();
    }
    return destroyObject(this);
  };

  /**
   * Computes the final camera location to view a rectangle adjusted for the current terrain.
   * If the terrain does not support availability, the height above the ellipsoid is used.
   *
   * @param {Rectangle} rectangle The rectangle being zoomed to.
   * @param {Scene} scene The scene being used.
   *
   * @returns {Cartographic} The optimal location to place the camera so that the entire rectangle is in view.
   *
   * @private
   */
  function computeFlyToLocationForRectangle(rectangle, scene) {
    var terrainProvider = scene.terrainProvider;
    var mapProjection = scene.mapProjection;
    var ellipsoid = mapProjection.ellipsoid;

    var positionWithoutTerrain;
    var tmp = scene.camera.getRectangleCameraCoordinates(rectangle);
    if (scene.mode === SceneMode$1.SCENE3D) {
      positionWithoutTerrain = ellipsoid.cartesianToCartographic(tmp);
    } else {
      positionWithoutTerrain = mapProjection.unproject(tmp);
    }

    if (!defined(terrainProvider)) {
      return when.resolve(positionWithoutTerrain);
    }

    return terrainProvider.readyPromise.then(function () {
      var availability = terrainProvider.availability;

      if (!defined(availability) || scene.mode === SceneMode$1.SCENE2D) {
        return positionWithoutTerrain;
      }

      var cartographics = [
        Rectangle.center(rectangle),
        Rectangle.southeast(rectangle),
        Rectangle.southwest(rectangle),
        Rectangle.northeast(rectangle),
        Rectangle.northwest(rectangle),
      ];

      return computeFlyToLocationForRectangle
        ._sampleTerrainMostDetailed(terrainProvider, cartographics)
        .then(function (positionsOnTerrain) {
          var maxHeight = positionsOnTerrain.reduce(function (currentMax, item) {
            return Math.max(item.height, currentMax);
          }, -Number.MAX_VALUE);

          var finalPosition = positionWithoutTerrain;
          finalPosition.height += maxHeight;
          return finalPosition;
        });
    });
  }

  //Exposed for testing.
  computeFlyToLocationForRectangle._sampleTerrainMostDetailed = sampleTerrainMostDetailed;

  /**
   * Creates a {@link Cesium3DTileset} instance for the
   * {@link https://cesium.com/content/cesium-osm-buildings/|Cesium OSM Buildings}
   * tileset.
   *
   * @function
   *
   * @param {Object} [options] Construction options. Any options allowed by the {@link Cesium3DTileset} constructor
   *        may be specified here. In addition to those, the following properties are supported:
   * @param {Color} [options.defaultColor=Color.WHITE] The default color to use for buildings
   *        that do not have a color. This parameter is ignored if <code>options.style</code> is specified.
   * @param {Cesium3DTileStyle} [options.style] The style to use with the tileset. If not
   *        specified, a default style is used which gives each building or building part a
   *        color inferred from its OpenStreetMap <code>tags</code>. If no color can be inferred,
   *        <code>options.defaultColor</code> is used.
   * @returns {Cesium3DTileset}
   *
   * @see Ion
   *
   * @example
   * // Create Cesium OSM Buildings with default styling
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.scene.primitives.add(Cesium.createOsmBuildings());
   *
   * @example
   * // Create Cesium OSM Buildings with a custom style highlighting
   * // schools and hospitals.
   * viewer.scene.primitives.add(Cesium.createOsmBuildings({
   *   style: new Cesium.Cesium3DTileStyle({
   *     color: {
   *       conditions: [
   *         ["${feature['building']} === 'hospital'", "color('#0000FF')"],
   *         ["${feature['building']} === 'school'", "color('#00FF00')"],
   *         [true, "color('#ffffff')"]
   *       ]
   *     }
   *   })
   * }));
   */
  function createOsmBuildings(options) {
    options = combine(options, {
      url: IonResource.fromAssetId(96188),
    });

    var tileset = new Cesium3DTileset(options);

    var style = options.style;

    if (!defined(style)) {
      var color = defaultValue(
        options.defaultColor,
        Color.WHITE
      ).toCssColorString();
      style = new Cesium3DTileStyle({
        color:
          "Boolean(${feature['cesium#color']}) ? color(${feature['cesium#color']}) : " +
          color,
      });
    }

    tileset.style = style;

    return tileset;
  }

  /**
   * Creates a {@link Primitive} to visualize well-known vector vertex attributes:
   * <code>normal</code>, <code>tangent</code>, and <code>bitangent</code>.  Normal
   * is red; tangent is green; and bitangent is blue.  If an attribute is not
   * present, it is not drawn.
   *
   * @function
   *
   * @param {Object} options Object with the following properties:
   * @param {Geometry} options.geometry The <code>Geometry</code> instance with the attribute.
   * @param {Number} [options.length=10000.0] The length of each line segment in meters.  This can be negative to point the vector in the opposite direction.
   * @param {Matrix4} [options.modelMatrix=Matrix4.IDENTITY] The model matrix that transforms to transform the geometry from model to world coordinates.
   * @returns {Primitive} A new <code>Primitive</code> instance with geometry for the vectors.
   *
   * @example
   * scene.primitives.add(Cesium.createTangentSpaceDebugPrimitive({
   *    geometry : instance.geometry,
   *    length : 100000.0,
   *    modelMatrix : instance.modelMatrix
   * }));
   */
  function createTangentSpaceDebugPrimitive(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var instances = [];
    var geometry = options.geometry;

    //>>includeStart('debug', pragmas.debug);
    if (!defined(geometry)) {
      throw new DeveloperError("options.geometry is required.");
    }
    //>>includeEnd('debug');

    if (!defined(geometry.attributes) || !defined(geometry.primitiveType)) {
      // to create the debug lines, we need the computed attributes.
      // compute them if they are undefined.
      geometry = geometry.constructor.createGeometry(geometry);
    }

    var attributes = geometry.attributes;
    var modelMatrix = Matrix4.clone(
      defaultValue(options.modelMatrix, Matrix4.IDENTITY)
    );
    var length = defaultValue(options.length, 10000.0);

    if (defined(attributes.normal)) {
      instances.push(
        new GeometryInstance({
          geometry: GeometryPipeline.createLineSegmentsForVectors(
            geometry,
            "normal",
            length
          ),
          attributes: {
            color: new ColorGeometryInstanceAttribute(1.0, 0.0, 0.0, 1.0),
          },
          modelMatrix: modelMatrix,
        })
      );
    }

    if (defined(attributes.tangent)) {
      instances.push(
        new GeometryInstance({
          geometry: GeometryPipeline.createLineSegmentsForVectors(
            geometry,
            "tangent",
            length
          ),
          attributes: {
            color: new ColorGeometryInstanceAttribute(0.0, 1.0, 0.0, 1.0),
          },
          modelMatrix: modelMatrix,
        })
      );
    }

    if (defined(attributes.bitangent)) {
      instances.push(
        new GeometryInstance({
          geometry: GeometryPipeline.createLineSegmentsForVectors(
            geometry,
            "bitangent",
            length
          ),
          attributes: {
            color: new ColorGeometryInstanceAttribute(0.0, 0.0, 1.0, 1.0),
          },
          modelMatrix: modelMatrix,
        })
      );
    }

    if (instances.length > 0) {
      return new Primitive({
        asynchronous: false,
        geometryInstances: instances,
        appearance: new PerInstanceColorAppearance({
          flat: true,
          translucent: false,
        }),
      });
    }

    return undefined;
  }

  /**
   * Creates an {@link IonImageryProvider} instance for ion's default global base imagery layer, currently Bing Maps.
   *
   * @function
   *
   * @param {Object} [options] Object with the following properties:
   * @param {IonWorldImageryStyle} [options.style=IonWorldImageryStyle] The style of base imagery, only AERIAL, AERIAL_WITH_LABELS, and ROAD are currently supported.
   * @returns {IonImageryProvider}
   *
   * @see Ion
   *
   * @example
   * // Create Cesium World Terrain with default settings
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *     imageryProvider : Cesium.createWorldImagery();
   * });
   *
   * @example
   * // Create Cesium World Terrain with water and normals.
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *     imageryProvider : Cesium.createWorldImagery({
   *         style: Cesium.IonWorldImageryStyle.AERIAL_WITH_LABELS
   *     })
   * });
   *
   */
  function createWorldImagery(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);
    var style = defaultValue(options.style, IonWorldImageryStyle$1.AERIAL);
    return new IonImageryProvider({
      assetId: style,
    });
  }

  /* jshint forin: false, bitwise: false */
  /*
  Copyright 2015-2018 Esri

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  A copy of the license and additional notices are located with the
  source distribution at:

  http://github.com/Esri/lerc/

  Contributors:  Johannes Schmid, (LERC v1)
                 Chayanika Khatua, (LERC v1)
                 Wenxue Ju (LERC v1, v2.x)
  */

  /* Copyright 2015-2018 Esri. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 @preserve */

  var tmp$6 = {};

  /**
   * a module for decoding LERC blobs
   * @module Lerc
   */
  (function() {
    //the original LercDecode for Version 1
    var LercDecode = (function() {

      // WARNING: This decoder version can only read old version 1 Lerc blobs. Use with caution.

      // Note: currently, this module only has an implementation for decoding LERC data, not encoding. The name of
      // the class was chosen to be future proof.

      var CntZImage = {};

      CntZImage.defaultNoDataValue = -3.4027999387901484e+38; // smallest Float32 value

      /**
       * Decode a LERC byte stream and return an object containing the pixel data and some required and optional
       * information about it, such as the image's width and height.
       *
       * @param {ArrayBuffer} input The LERC input byte stream
       * @param {object} [options] Decoding options, containing any of the following properties:
       * @config {number} [inputOffset = 0]
       *        Skip the first inputOffset bytes of the input byte stream. A valid LERC file is expected at that position.
       * @config {Uint8Array} [encodedMask = null]
       *        If specified, the decoder will not read mask information from the input and use the specified encoded
       *        mask data instead. Mask header/data must not be present in the LERC byte stream in this case.
       * @config {number} [noDataValue = LercCode.defaultNoDataValue]
       *        Pixel value to use for masked pixels.
       * @config {ArrayBufferView|Array} [pixelType = Float32Array]
       *        The desired type of the pixelData array in the return value. Note that it is the caller's responsibility to
       *        provide an appropriate noDataValue if the default pixelType is overridden.
       * @config {boolean} [returnMask = false]
       *        If true, the return value will contain a maskData property of type Uint8Array which has one element per
       *        pixel, the value of which is 1 or 0 depending on whether that pixel's data is present or masked. If the
       *        input LERC data does not contain a mask, maskData will not be returned.
       * @config {boolean} [returnEncodedMask = false]
       *        If true, the return value will contain a encodedMaskData property, which can be passed into encode() as
       *        encodedMask.
       * @config {boolean} [returnFileInfo = false]
       *        If true, the return value will have a fileInfo property that contains metadata obtained from the
       *        LERC headers and the decoding process.
       * @config {boolean} [computeUsedBitDepths = false]
       *        If true, the fileInfo property in the return value will contain the set of all block bit depths
       *        encountered during decoding. Will only have an effect if returnFileInfo option is true.
       * @returns {{width, height, pixelData, minValue, maxValue, noDataValue, maskData, encodedMaskData, fileInfo}}
       */
      CntZImage.decode = function(input, options) {
        options = options || {};

        var skipMask = options.encodedMaskData || (options.encodedMaskData === null);
        var parsedData = parse(input, options.inputOffset || 0, skipMask);

        var noDataValue = (options.noDataValue !== null) ? options.noDataValue : CntZImage.defaultNoDataValue;

        var uncompressedData = uncompressPixelValues(parsedData, options.pixelType || Float32Array,
          options.encodedMaskData, noDataValue, options.returnMask);

        var result = {
          width: parsedData.width,
          height: parsedData.height,
          pixelData: uncompressedData.resultPixels,
          minValue: uncompressedData.minValue,
          maxValue: parsedData.pixels.maxValue,
          noDataValue: noDataValue
        };

        if (uncompressedData.resultMask) {
          result.maskData = uncompressedData.resultMask;
        }

        if (options.returnEncodedMask && parsedData.mask) {
          result.encodedMaskData = parsedData.mask.bitset ? parsedData.mask.bitset : null;
        }

        if (options.returnFileInfo) {
          result.fileInfo = formatFileInfo(parsedData);
          if (options.computeUsedBitDepths) {
            result.fileInfo.bitDepths = computeUsedBitDepths(parsedData);
          }
        }

        return result;
      };

      var uncompressPixelValues = function(data, TypedArrayClass, maskBitset, noDataValue, storeDecodedMask) {
        var blockIdx = 0;
        var numX = data.pixels.numBlocksX;
        var numY = data.pixels.numBlocksY;
        var blockWidth = Math.floor(data.width / numX);
        var blockHeight = Math.floor(data.height / numY);
        var scale = 2 * data.maxZError;
        var minValue = Number.MAX_VALUE, currentValue;
        maskBitset = maskBitset || ((data.mask) ? data.mask.bitset : null);

        var resultPixels, resultMask;
        resultPixels = new TypedArrayClass(data.width * data.height);
        if (storeDecodedMask && maskBitset) {
          resultMask = new Uint8Array(data.width * data.height);
        }
        var blockDataBuffer = new Float32Array(blockWidth * blockHeight);

        var xx, yy;
        for (var y = 0; y <= numY; y++) {
          var thisBlockHeight = (y !== numY) ? blockHeight : (data.height % numY);
          if (thisBlockHeight === 0) {
            continue;
          }
          for (var x = 0; x <= numX; x++) {
            var thisBlockWidth = (x !== numX) ? blockWidth : (data.width % numX);
            if (thisBlockWidth === 0) {
              continue;
            }

            var outPtr = y * data.width * blockHeight + x * blockWidth;
            var outStride = data.width - thisBlockWidth;

            var block = data.pixels.blocks[blockIdx];

            var blockData, blockPtr, constValue;
            if (block.encoding < 2) {
              // block is either uncompressed or bit-stuffed (encodings 0 and 1)
              if (block.encoding === 0) {
                // block is uncompressed
                blockData = block.rawData;
              } else {
                // block is bit-stuffed
                unstuff(block.stuffedData, block.bitsPerPixel, block.numValidPixels, block.offset, scale, blockDataBuffer, data.pixels.maxValue);
                blockData = blockDataBuffer;
              }
              blockPtr = 0;
            }
            else if (block.encoding === 2) {
              // block is all 0
              constValue = 0;
            }
            else {
              // block has constant value (encoding === 3)
              constValue = block.offset;
            }

            var maskByte;
            if (maskBitset) {
              for (yy = 0; yy < thisBlockHeight; yy++) {
                if (outPtr & 7) {
                  //
                  maskByte = maskBitset[outPtr >> 3];
                  maskByte <<= outPtr & 7;
                }
                for (xx = 0; xx < thisBlockWidth; xx++) {
                  if (!(outPtr & 7)) {
                    // read next byte from mask
                    maskByte = maskBitset[outPtr >> 3];
                  }
                  if (maskByte & 128) {
                    // pixel data present
                    if (resultMask) {
                      resultMask[outPtr] = 1;
                    }
                    currentValue = (block.encoding < 2) ? blockData[blockPtr++] : constValue;
                    minValue = minValue > currentValue ? currentValue : minValue;
                    resultPixels[outPtr++] = currentValue;
                  } else {
                    // pixel data not present
                    if (resultMask) {
                      resultMask[outPtr] = 0;
                    }
                    resultPixels[outPtr++] = noDataValue;
                  }
                  maskByte <<= 1;
                }
                outPtr += outStride;
              }
            } else {
              // mask not present, simply copy block over
              if (block.encoding < 2) {
                // duplicating this code block for performance reasons
                // blockData case:
                for (yy = 0; yy < thisBlockHeight; yy++) {
                  for (xx = 0; xx < thisBlockWidth; xx++) {
                    currentValue = blockData[blockPtr++];
                    minValue = minValue > currentValue ? currentValue : minValue;
                    resultPixels[outPtr++] = currentValue;
                  }
                  outPtr += outStride;
                }
              }
              else {
                // constValue case:
                minValue = minValue > constValue ? constValue : minValue;
                for (yy = 0; yy < thisBlockHeight; yy++) {
                  for (xx = 0; xx < thisBlockWidth; xx++) {
                    resultPixels[outPtr++] = constValue;
                  }
                  outPtr += outStride;
                }
              }
            }
            if ((block.encoding === 1) && (blockPtr !== block.numValidPixels)) {
              throw "Block and Mask do not match";
            }
            blockIdx++;
          }
        }

        return {
          resultPixels: resultPixels,
          resultMask: resultMask,
          minValue: minValue
        };
      };

      var formatFileInfo = function(data) {
        return {
          "fileIdentifierString": data.fileIdentifierString,
          "fileVersion": data.fileVersion,
          "imageType": data.imageType,
          "height": data.height,
          "width": data.width,
          "maxZError": data.maxZError,
          "eofOffset": data.eofOffset,
          "mask": data.mask ? {
            "numBlocksX": data.mask.numBlocksX,
            "numBlocksY": data.mask.numBlocksY,
            "numBytes": data.mask.numBytes,
            "maxValue": data.mask.maxValue
          } : null,
          "pixels": {
            "numBlocksX": data.pixels.numBlocksX,
            "numBlocksY": data.pixels.numBlocksY,
            "numBytes": data.pixels.numBytes,
            "maxValue": data.pixels.maxValue,
            "noDataValue": data.noDataValue
          }
        };
      };

      var computeUsedBitDepths = function(data) {
        var numBlocks = data.pixels.numBlocksX * data.pixels.numBlocksY;
        var bitDepths = {};
        for (var i = 0; i < numBlocks; i++) {
          var block = data.pixels.blocks[i];
          if (block.encoding === 0) {
            bitDepths.float32 = true;
          } else if (block.encoding === 1) {
            bitDepths[block.bitsPerPixel] = true;
          } else {
            bitDepths[0] = true;
          }
        }

        return Object.keys(bitDepths);
      };

      var parse = function(input, fp, skipMask) {
        var data = {};

        // File header
        var fileIdView = new Uint8Array(input, fp, 10);
        data.fileIdentifierString = String.fromCharCode.apply(null, fileIdView);
        if (data.fileIdentifierString.trim() !== "CntZImage") {
          throw "Unexpected file identifier string: " + data.fileIdentifierString;
        }
        fp += 10;
        var view = new DataView(input, fp, 24);
        data.fileVersion = view.getInt32(0, true);
        data.imageType = view.getInt32(4, true);
        data.height = view.getUint32(8, true);
        data.width = view.getUint32(12, true);
        data.maxZError = view.getFloat64(16, true);
        fp += 24;

        // Mask Header
        if (!skipMask) {
          view = new DataView(input, fp, 16);
          data.mask = {};
          data.mask.numBlocksY = view.getUint32(0, true);
          data.mask.numBlocksX = view.getUint32(4, true);
          data.mask.numBytes = view.getUint32(8, true);
          data.mask.maxValue = view.getFloat32(12, true);
          fp += 16;

          // Mask Data
          if (data.mask.numBytes > 0) {
            var bitset = new Uint8Array(Math.ceil(data.width * data.height / 8));
            view = new DataView(input, fp, data.mask.numBytes);
            var cnt = view.getInt16(0, true);
            var ip = 2, op = 0;
            do {
              if (cnt > 0) {
                while (cnt--) { bitset[op++] = view.getUint8(ip++); }
              } else {
                var val = view.getUint8(ip++);
                cnt = -cnt;
                while (cnt--) { bitset[op++] = val; }
              }
              cnt = view.getInt16(ip, true);
              ip += 2;
            } while (ip < data.mask.numBytes);
            if ((cnt !== -32768) || (op < bitset.length)) {
              throw "Unexpected end of mask RLE encoding";
            }
            data.mask.bitset = bitset;
            fp += data.mask.numBytes;
          }
          else if ((data.mask.numBytes | data.mask.numBlocksY | data.mask.maxValue) === 0) {  // Special case, all nodata
            data.mask.bitset = new Uint8Array(Math.ceil(data.width * data.height / 8));
          }
        }

        // Pixel Header
        view = new DataView(input, fp, 16);
        data.pixels = {};
        data.pixels.numBlocksY = view.getUint32(0, true);
        data.pixels.numBlocksX = view.getUint32(4, true);
        data.pixels.numBytes = view.getUint32(8, true);
        data.pixels.maxValue = view.getFloat32(12, true);
        fp += 16;

        var numBlocksX = data.pixels.numBlocksX;
        var numBlocksY = data.pixels.numBlocksY;
        // the number of blocks specified in the header does not take into account the blocks at the end of
        // each row/column with a special width/height that make the image complete in case the width is not
        // evenly divisible by the number of blocks.
        var actualNumBlocksX = numBlocksX + ((data.width % numBlocksX) > 0 ? 1 : 0);
        var actualNumBlocksY = numBlocksY + ((data.height % numBlocksY) > 0 ? 1 : 0);
        data.pixels.blocks = new Array(actualNumBlocksX * actualNumBlocksY);
        var blockI = 0;
        for (var blockY = 0; blockY < actualNumBlocksY; blockY++) {
          for (var blockX = 0; blockX < actualNumBlocksX; blockX++) {

            // Block
            var size = 0;
            var bytesLeft = input.byteLength - fp;
            view = new DataView(input, fp, Math.min(10, bytesLeft));
            var block = {};
            data.pixels.blocks[blockI++] = block;
            var headerByte = view.getUint8(0); size++;
            block.encoding = headerByte & 63;
            if (block.encoding > 3) {
              throw "Invalid block encoding (" + block.encoding + ")";
            }
            if (block.encoding === 2) {
              fp++;
              continue;
            }
            if ((headerByte !== 0) && (headerByte !== 2)) {
              headerByte >>= 6;
              block.offsetType = headerByte;
              if (headerByte === 2) {
                block.offset = view.getInt8(1); size++;
              } else if (headerByte === 1) {
                block.offset = view.getInt16(1, true); size += 2;
              } else if (headerByte === 0) {
                block.offset = view.getFloat32(1, true); size += 4;
              } else {
                throw "Invalid block offset type";
              }

              if (block.encoding === 1) {
                headerByte = view.getUint8(size); size++;
                block.bitsPerPixel = headerByte & 63;
                headerByte >>= 6;
                block.numValidPixelsType = headerByte;
                if (headerByte === 2) {
                  block.numValidPixels = view.getUint8(size); size++;
                } else if (headerByte === 1) {
                  block.numValidPixels = view.getUint16(size, true); size += 2;
                } else if (headerByte === 0) {
                  block.numValidPixels = view.getUint32(size, true); size += 4;
                } else {
                  throw "Invalid valid pixel count type";
                }
              }
            }
            fp += size;

            if (block.encoding === 3) {
              continue;
            }

            var arrayBuf, store8;
            if (block.encoding === 0) {
              var numPixels = (data.pixels.numBytes - 1) / 4;
              if (numPixels !== Math.floor(numPixels)) {
                throw "uncompressed block has invalid length";
              }
              arrayBuf = new ArrayBuffer(numPixels * 4);
              store8 = new Uint8Array(arrayBuf);
              store8.set(new Uint8Array(input, fp, numPixels * 4));
              var rawData = new Float32Array(arrayBuf);
              block.rawData = rawData;
              fp += numPixels * 4;
            } else if (block.encoding === 1) {
              var dataBytes = Math.ceil(block.numValidPixels * block.bitsPerPixel / 8);
              var dataWords = Math.ceil(dataBytes / 4);
              arrayBuf = new ArrayBuffer(dataWords * 4);
              store8 = new Uint8Array(arrayBuf);
              store8.set(new Uint8Array(input, fp, dataBytes));
              block.stuffedData = new Uint32Array(arrayBuf);
              fp += dataBytes;
            }
          }
        }
        data.eofOffset = fp;
        return data;
      };

      var unstuff = function(src, bitsPerPixel, numPixels, offset, scale, dest, maxValue) {
        var bitMask = (1 << bitsPerPixel) - 1;
        var i = 0, o;
        var bitsLeft = 0;
        var n, buffer;
        var nmax = Math.ceil((maxValue - offset) / scale);
        // get rid of trailing bytes that are already part of next block
        var numInvalidTailBytes = src.length * 4 - Math.ceil(bitsPerPixel * numPixels / 8);
        src[src.length - 1] <<= 8 * numInvalidTailBytes;

        for (o = 0; o < numPixels; o++) {
          if (bitsLeft === 0) {
            buffer = src[i++];
            bitsLeft = 32;
          }
          if (bitsLeft >= bitsPerPixel) {
            n = (buffer >>> (bitsLeft - bitsPerPixel)) & bitMask;
            bitsLeft -= bitsPerPixel;
          } else {
            var missingBits = (bitsPerPixel - bitsLeft);
            n = ((buffer & bitMask) << missingBits) & bitMask;
            buffer = src[i++];
            bitsLeft = 32 - missingBits;
            n += (buffer >>> bitsLeft);
          }
          //pixel values may exceed max due to quantization
          dest[o] = n < nmax ? offset + n * scale : maxValue;
        }
        return dest;
      };

      return CntZImage;
    })();

    //version 2. Supports 2.1, 2.2, 2.3
    var Lerc2Decode = (function() {
      // Note: currently, this module only has an implementation for decoding LERC data, not encoding. The name of
      // the class was chosen to be future proof, following LercDecode.

      /*****************************************
      * private static class bitsutffer used by Lerc2Decode
      *******************************************/
      var BitStuffer = {
        //methods ending with 2 are for the new byte order used by Lerc2.3 and above.
        //originalUnstuff is used to unpack Huffman code table. code is duplicated to unstuffx for performance reasons.
        unstuff: function(src, dest, bitsPerPixel, numPixels, lutArr, offset, scale, maxValue) {
          var bitMask = (1 << bitsPerPixel) - 1;
          var i = 0, o;
          var bitsLeft = 0;
          var n, buffer, missingBits, nmax;

          // get rid of trailing bytes that are already part of next block
          var numInvalidTailBytes = src.length * 4 - Math.ceil(bitsPerPixel * numPixels / 8);
          src[src.length - 1] <<= 8 * numInvalidTailBytes;
          if (lutArr) {
            for (o = 0; o < numPixels; o++) {
              if (bitsLeft === 0) {
                buffer = src[i++];
                bitsLeft = 32;
              }
              if (bitsLeft >= bitsPerPixel) {
                n = (buffer >>> (bitsLeft - bitsPerPixel)) & bitMask;
                bitsLeft -= bitsPerPixel;
              }
              else {
                missingBits = (bitsPerPixel - bitsLeft);
                n = ((buffer & bitMask) << missingBits) & bitMask;
                buffer = src[i++];
                bitsLeft = 32 - missingBits;
                n += (buffer >>> bitsLeft);
              }
              dest[o] = lutArr[n];//offset + lutArr[n] * scale;
            }
          }
          else {
            nmax = Math.ceil((maxValue - offset) / scale);
            for (o = 0; o < numPixels; o++) {
              if (bitsLeft === 0) {
                buffer = src[i++];
                bitsLeft = 32;
              }
              if (bitsLeft >= bitsPerPixel) {
                n = (buffer >>> (bitsLeft - bitsPerPixel)) & bitMask;
                bitsLeft -= bitsPerPixel;
              }
              else {
                missingBits = (bitsPerPixel - bitsLeft);
                n = ((buffer & bitMask) << missingBits) & bitMask;
                buffer = src[i++];
                bitsLeft = 32 - missingBits;
                n += (buffer >>> bitsLeft);
              }
              //pixel values may exceed max due to quantization
              dest[o] = n < nmax ? offset + n * scale : maxValue;
            }
          }
        },

        unstuffLUT: function(src, bitsPerPixel, numPixels, offset, scale, maxValue) {
          var bitMask = (1 << bitsPerPixel) - 1;
          var i = 0, o = 0, missingBits = 0, bitsLeft = 0, n = 0;
          var buffer;
          var dest = [];

          // get rid of trailing bytes that are already part of next block
          var numInvalidTailBytes = src.length * 4 - Math.ceil(bitsPerPixel * numPixels / 8);
          src[src.length - 1] <<= 8 * numInvalidTailBytes;

          var nmax = Math.ceil((maxValue - offset) / scale);
          for (o = 0; o < numPixels; o++) {
            if (bitsLeft === 0) {
              buffer = src[i++];
              bitsLeft = 32;
            }
            if (bitsLeft >= bitsPerPixel) {
              n = (buffer >>> (bitsLeft - bitsPerPixel)) & bitMask;
              bitsLeft -= bitsPerPixel;
            } else {
              missingBits = (bitsPerPixel - bitsLeft);
              n = ((buffer & bitMask) << missingBits) & bitMask;
              buffer = src[i++];
              bitsLeft = 32 - missingBits;
              n += (buffer >>> bitsLeft);
            }
            //dest.push(n);
            dest[o] = n < nmax ? offset + n * scale : maxValue;
          }
          dest.unshift(offset);//1st one
          return dest;
        },

        unstuff2: function(src, dest, bitsPerPixel, numPixels, lutArr, offset, scale, maxValue) {
          var bitMask = (1 << bitsPerPixel) - 1;
          var i = 0, o;
          var bitsLeft = 0, bitPos = 0;
          var n, buffer, missingBits;
          if (lutArr) {
            for (o = 0; o < numPixels; o++) {
              if (bitsLeft === 0) {
                buffer = src[i++];
                bitsLeft = 32;
                bitPos = 0;
              }
              if (bitsLeft >= bitsPerPixel) {
                n = ((buffer >>> bitPos) & bitMask);
                bitsLeft -= bitsPerPixel;
                bitPos += bitsPerPixel;
              } else {
                missingBits = (bitsPerPixel - bitsLeft);
                n = (buffer >>> bitPos) & bitMask;
                buffer = src[i++];
                bitsLeft = 32 - missingBits;
                n |= (buffer & ((1 << missingBits) - 1)) << (bitsPerPixel - missingBits);
                bitPos = missingBits;
              }
              dest[o] = lutArr[n];
            }
          }
          else {
            var nmax = Math.ceil((maxValue - offset) / scale);
            for (o = 0; o < numPixels; o++) {
              if (bitsLeft === 0) {
                buffer = src[i++];
                bitsLeft = 32;
                bitPos = 0;
              }
              if (bitsLeft >= bitsPerPixel) {
                //no unsigned left shift
                n = ((buffer >>> bitPos) & bitMask);
                bitsLeft -= bitsPerPixel;
                bitPos += bitsPerPixel;
              } else {
                missingBits = (bitsPerPixel - bitsLeft);
                n = (buffer >>> bitPos) & bitMask;//((buffer & bitMask) << missingBits) & bitMask;
                buffer = src[i++];
                bitsLeft = 32 - missingBits;
                n |= (buffer & ((1 << missingBits) - 1)) << (bitsPerPixel - missingBits);
                bitPos = missingBits;
              }
              //pixel values may exceed max due to quantization
              dest[o] = n < nmax ? offset + n * scale : maxValue;
            }
          }
          return dest;
        },

        unstuffLUT2: function(src, bitsPerPixel, numPixels, offset, scale, maxValue) {
          var bitMask = (1 << bitsPerPixel) - 1;
          var i = 0, o = 0, missingBits = 0, bitsLeft = 0, n = 0, bitPos = 0;
          var buffer;
          var dest = [];
          var nmax = Math.ceil((maxValue - offset) / scale);
          for (o = 0; o < numPixels; o++) {
            if (bitsLeft === 0) {
              buffer = src[i++];
              bitsLeft = 32;
              bitPos = 0;
            }
            if (bitsLeft >= bitsPerPixel) {
              //no unsigned left shift
              n = ((buffer >>> bitPos) & bitMask);
              bitsLeft -= bitsPerPixel;
              bitPos += bitsPerPixel;
            } else {
              missingBits = (bitsPerPixel - bitsLeft);
              n = (buffer >>> bitPos) & bitMask;//((buffer & bitMask) << missingBits) & bitMask;
              buffer = src[i++];
              bitsLeft = 32 - missingBits;
              n |= (buffer & ((1 << missingBits) - 1)) << (bitsPerPixel - missingBits);
              bitPos = missingBits;
            }
            //dest.push(n);
            dest[o] = n < nmax ? offset + n * scale : maxValue;
          }
          dest.unshift(offset);
          return dest;
        },

        originalUnstuff: function(src, dest, bitsPerPixel, numPixels) {
          var bitMask = (1 << bitsPerPixel) - 1;
          var i = 0, o;
          var bitsLeft = 0;
          var n, buffer, missingBits;

          // get rid of trailing bytes that are already part of next block
          var numInvalidTailBytes = src.length * 4 - Math.ceil(bitsPerPixel * numPixels / 8);
          src[src.length - 1] <<= 8 * numInvalidTailBytes;

          for (o = 0; o < numPixels; o++) {
            if (bitsLeft === 0) {
              buffer = src[i++];
              bitsLeft = 32;
            }
            if (bitsLeft >= bitsPerPixel) {
              n = (buffer >>> (bitsLeft - bitsPerPixel)) & bitMask;
              bitsLeft -= bitsPerPixel;
            }
            else {
              missingBits = (bitsPerPixel - bitsLeft);
              n = ((buffer & bitMask) << missingBits) & bitMask;
              buffer = src[i++];
              bitsLeft = 32 - missingBits;
              n += (buffer >>> bitsLeft);
            }
            dest[o] = n;
          }
          return dest;
        },

        originalUnstuff2: function(src, dest, bitsPerPixel, numPixels) {
          var bitMask = (1 << bitsPerPixel) - 1;
          var i = 0, o;
          var bitsLeft = 0, bitPos = 0;
          var n, buffer, missingBits;
          //micro-optimizations
          for (o = 0; o < numPixels; o++) {
            if (bitsLeft === 0) {
              buffer = src[i++];
              bitsLeft = 32;
              bitPos = 0;
            }
            if (bitsLeft >= bitsPerPixel) {
              //no unsigned left shift
              n = ((buffer >>> bitPos) & bitMask);
              bitsLeft -= bitsPerPixel;
              bitPos += bitsPerPixel;
            } else {
              missingBits = (bitsPerPixel - bitsLeft);
              n = (buffer >>> bitPos) & bitMask;//((buffer & bitMask) << missingBits) & bitMask;
              buffer = src[i++];
              bitsLeft = 32 - missingBits;
              n |= (buffer & ((1 << missingBits) - 1)) << (bitsPerPixel - missingBits);
              bitPos = missingBits;
            }
            dest[o] = n;
          }
          return dest;
        }
      };

      /*****************************************
      *private static class used by Lerc2Decode
      ******************************************/
      var Lerc2Helpers = {
        HUFFMAN_LUT_BITS_MAX: 12, //use 2^12 lut, treat it like constant
        computeChecksumFletcher32: function(input) {

          var sum1 = 0xffff, sum2 = 0xffff;
          var len = input.length;
          var words = Math.floor(len / 2);
          var i = 0;
          while (words) {
            var tlen = (words >= 359) ? 359 : words;
            words -= tlen;
            do {
              sum1 += (input[i++] << 8);
              sum2 += sum1 += input[i++];
            } while (--tlen);

            sum1 = (sum1 & 0xffff) + (sum1 >>> 16);
            sum2 = (sum2 & 0xffff) + (sum2 >>> 16);
          }

          // add the straggler byte if it exists
          if (len & 1) {
            sum2 += sum1 += (input[i] << 8);
          }
          // second reduction step to reduce sums to 16 bits
          sum1 = (sum1 & 0xffff) + (sum1 >>> 16);
          sum2 = (sum2 & 0xffff) + (sum2 >>> 16);

          return (sum2 << 16 | sum1) >>> 0;
        },

        readHeaderInfo: function(input, data) {
          var ptr = data.ptr;
          var fileIdView = new Uint8Array(input, ptr, 6);
          var headerInfo = {};
          headerInfo.fileIdentifierString = String.fromCharCode.apply(null, fileIdView);
          if (headerInfo.fileIdentifierString.lastIndexOf("Lerc2", 0) !== 0) {
            throw "Unexpected file identifier string (expect Lerc2 ): " + headerInfo.fileIdentifierString;
          }
          ptr += 6;
          var view = new DataView(input, ptr, 8);
          var fileVersion = view.getInt32(0, true);
          headerInfo.fileVersion = fileVersion;
          ptr += 4;
          if (fileVersion >= 3) {
            headerInfo.checksum = view.getUint32(4, true); //nrows
            ptr += 4;
          }

          //keys start from here
          view = new DataView(input, ptr, 12);
          headerInfo.height = view.getUint32(0, true); //nrows
          headerInfo.width = view.getUint32(4, true); //ncols
          ptr += 8;
          if (fileVersion >= 4) {
            headerInfo.numDims = view.getUint32(8, true);
            ptr += 4;
          }
          else {
            headerInfo.numDims = 1;
          }

          view = new DataView(input, ptr, 40);
          headerInfo.numValidPixel = view.getUint32(0, true);
          headerInfo.microBlockSize = view.getInt32(4, true);
          headerInfo.blobSize = view.getInt32(8, true);
          headerInfo.imageType = view.getInt32(12, true);

          headerInfo.maxZError = view.getFloat64(16, true);
          headerInfo.zMin = view.getFloat64(24, true);
          headerInfo.zMax = view.getFloat64(32, true);
          ptr += 40;
          data.headerInfo = headerInfo;
          data.ptr = ptr;

          var checksum, keyLength;
          if (fileVersion >= 3) {
            keyLength = fileVersion >= 4 ? 52 : 48;
            checksum = this.computeChecksumFletcher32(new Uint8Array(input, ptr - keyLength, headerInfo.blobSize - 14));
            if (checksum !== headerInfo.checksum) {
              throw "Checksum failed.";
            }
          }
          return true;
        },

        checkMinMaxRanges: function(input, data) {
          var headerInfo = data.headerInfo;
          var OutPixelTypeArray = this.getDataTypeArray(headerInfo.imageType);
          var rangeBytes = headerInfo.numDims * this.getDataTypeSize(headerInfo.imageType);
          var minValues = this.readSubArray(input, data.ptr, OutPixelTypeArray, rangeBytes);
          var maxValues = this.readSubArray(input, data.ptr + rangeBytes, OutPixelTypeArray, rangeBytes);
          data.ptr += (2 * rangeBytes);
          var i, equal = true;
          for (i = 0; i < headerInfo.numDims; i++) {
            if (minValues[i] !== maxValues[i]) {
              equal = false;
              break;
            }
          }
          headerInfo.minValues = minValues;
          headerInfo.maxValues = maxValues;
          return equal;
        },

        readSubArray: function(input, ptr, OutPixelTypeArray, numBytes) {
          var rawData;
          if (OutPixelTypeArray === Uint8Array) {
            rawData = new Uint8Array(input, ptr, numBytes);
          }
          else {
            var arrayBuf = new ArrayBuffer(numBytes);
            var store8 = new Uint8Array(arrayBuf);
            store8.set(new Uint8Array(input, ptr, numBytes));
            rawData = new OutPixelTypeArray(arrayBuf);
          }
          return rawData;
        },

        readMask: function(input, data) {
          var ptr = data.ptr;
          var headerInfo = data.headerInfo;
          var numPixels = headerInfo.width * headerInfo.height;
          var numValidPixel = headerInfo.numValidPixel;

          var view = new DataView(input, ptr, 4);
          var mask = {};
          mask.numBytes = view.getUint32(0, true);
          ptr += 4;

          // Mask Data
          if ((0 === numValidPixel || numPixels === numValidPixel) && 0 !== mask.numBytes) {
            throw ("invalid mask");
          }
          var bitset, resultMask;
          if (numValidPixel === 0) {
            bitset = new Uint8Array(Math.ceil(numPixels / 8));
            mask.bitset = bitset;
            resultMask = new Uint8Array(numPixels);
            data.pixels.resultMask = resultMask;
            ptr += mask.numBytes;
          }// ????? else if (data.mask.numBytes > 0 && data.mask.numBytes< data.numValidPixel) {
          else if (mask.numBytes > 0) {
            bitset = new Uint8Array(Math.ceil(numPixels / 8));
            view = new DataView(input, ptr, mask.numBytes);
            var cnt = view.getInt16(0, true);
            var ip = 2, op = 0, val = 0;
            do {
              if (cnt > 0) {
                while (cnt--) { bitset[op++] = view.getUint8(ip++); }
              } else {
                val = view.getUint8(ip++);
                cnt = -cnt;
                while (cnt--) { bitset[op++] = val; }
              }
              cnt = view.getInt16(ip, true);
              ip += 2;
            } while (ip < mask.numBytes);
            if ((cnt !== -32768) || (op < bitset.length)) {
              throw "Unexpected end of mask RLE encoding";
            }

            resultMask = new Uint8Array(numPixels);
            var mb = 0, k = 0;

            for (k = 0; k < numPixels; k++) {
              if (k & 7) {
                mb = bitset[k >> 3];
                mb <<= k & 7;
              }
              else {
                mb = bitset[k >> 3];
              }
              if (mb & 128) {
                resultMask[k] = 1;
              }
            }
            data.pixels.resultMask = resultMask;

            mask.bitset = bitset;
            ptr += mask.numBytes;
          }
          data.ptr = ptr;
          data.mask = mask;
          return true;
        },

        readDataOneSweep: function(input, data, OutPixelTypeArray) {
          var ptr = data.ptr;
          var headerInfo = data.headerInfo;
          var numDims = headerInfo.numDims;
          var numPixels = headerInfo.width * headerInfo.height;
          var imageType = headerInfo.imageType;
          var numBytes = headerInfo.numValidPixel * Lerc2Helpers.getDataTypeSize(imageType) * numDims;
          //data.pixels.numBytes = numBytes;
          var rawData;
          var mask = data.pixels.resultMask;
          if (OutPixelTypeArray === Uint8Array) {
            rawData = new Uint8Array(input, ptr, numBytes);
          }
          else {
            var arrayBuf = new ArrayBuffer(numBytes);
            var store8 = new Uint8Array(arrayBuf);
            store8.set(new Uint8Array(input, ptr, numBytes));
            rawData = new OutPixelTypeArray(arrayBuf);
          }
          if (rawData.length === numPixels * numDims) {
            data.pixels.resultPixels = rawData;
          }
          else  //mask
          {
            data.pixels.resultPixels = new OutPixelTypeArray(numPixels * numDims);
            var z = 0, k = 0, i = 0, nStart = 0;
            if (numDims > 1) {
              for (i=0; i < numDims; i++) {
                nStart = i * numPixels;
                for (k = 0; k < numPixels; k++) {
                  if (mask[k]) {
                    data.pixels.resultPixels[nStart + k] = rawData[z++];
                  }
                }
              }
            }
            else {
              for (k = 0; k < numPixels; k++) {
                if (mask[k]) {
                  data.pixels.resultPixels[k] = rawData[z++];
                }
              }
            }
          }
          ptr += numBytes;
          data.ptr = ptr;       //return data;
          return true;
        },

        readHuffmanTree: function(input, data) {
          var BITS_MAX = this.HUFFMAN_LUT_BITS_MAX; //8 is slow for the large test image
          //var size_max = 1 << BITS_MAX;
          /* ************************
           * reading code table
           *************************/
          var view = new DataView(input, data.ptr, 16);
          data.ptr += 16;
          var version = view.getInt32(0, true);
          if (version < 2) {
            throw "unsupported Huffman version";
          }
          var size = view.getInt32(4, true);
          var i0 = view.getInt32(8, true);
          var i1 = view.getInt32(12, true);
          if (i0 >= i1) {
            return false;
          }
          var blockDataBuffer = new Uint32Array(i1 - i0);
          Lerc2Helpers.decodeBits(input, data, blockDataBuffer);
          var codeTable = []; //size
          var i, j, k, len;

          for (i = i0; i < i1; i++) {
            j = i - (i < size ? 0 : size);//wrap around
            codeTable[j] = { first: blockDataBuffer[i - i0], second: null };
          }

          var dataBytes = input.byteLength - data.ptr;
          var dataWords = Math.ceil(dataBytes / 4);
          var arrayBuf = new ArrayBuffer(dataWords * 4);
          var store8 = new Uint8Array(arrayBuf);
          store8.set(new Uint8Array(input, data.ptr, dataBytes));
          var stuffedData = new Uint32Array(arrayBuf); //must start from x*4
          var bitPos = 0, word, srcPtr = 0;
          word = stuffedData[0];
          for (i = i0; i < i1; i++) {
            j = i - (i < size ? 0 : size);//wrap around
            len = codeTable[j].first;
            if (len > 0) {
              codeTable[j].second = (word << bitPos) >>> (32 - len);

              if (32 - bitPos >= len) {
                bitPos += len;
                if (bitPos === 32) {
                  bitPos = 0;
                  srcPtr++;
                  word = stuffedData[srcPtr];
                }
              }
              else {
                bitPos += len - 32;
                srcPtr++;
                word = stuffedData[srcPtr];
                codeTable[j].second |= word >>> (32 - bitPos);
              }
            }
          }

          //finished reading code table

          /* ************************
           * building lut
           *************************/
          var numBitsLUT = 0, numBitsLUTQick = 0;
          var tree = new TreeNode();
          for (i = 0; i < codeTable.length; i++) {
            if (codeTable[i] !== undefined) {
              numBitsLUT = Math.max(numBitsLUT, codeTable[i].first);
            }
          }
          if (numBitsLUT >= BITS_MAX) {
            numBitsLUTQick = BITS_MAX;
          }
          else {
            numBitsLUTQick = numBitsLUT;
          }
          if (numBitsLUT >= 30) {
            console.log("WARning, large NUM LUT BITS IS " + numBitsLUT);
          }
          var decodeLut = [], entry, code, numEntries, jj, currentBit, node;
          for (i = i0; i < i1; i++) {
            j = i - (i < size ? 0 : size);//wrap around
            len = codeTable[j].first;
            if (len > 0) {
              entry = [len, j];
              if (len <= numBitsLUTQick) {
                code = codeTable[j].second << (numBitsLUTQick - len);
                numEntries = 1 << (numBitsLUTQick - len);
                for (k = 0; k < numEntries; k++) {
                  decodeLut[code | k] = entry;
                }
              }
              else {
                //build tree
                code = codeTable[j].second;
                node = tree;
                for (jj = len - 1; jj >= 0; jj--) {
                  currentBit = code >>> jj & 1; //no left shift as length could be 30,31
                  if (currentBit) {
                    if (!node.right) {
                      node.right = new TreeNode();
                    }
                    node = node.right;
                  }
                  else {
                    if (!node.left) {
                      node.left = new TreeNode();
                    }
                    node = node.left;
                  }
                  if (jj === 0 && !node.val) {
                    node.val = entry[1];
                  }
                }
              }
            }
          }
          return {
            decodeLut: decodeLut,
            numBitsLUTQick: numBitsLUTQick,
            numBitsLUT: numBitsLUT,
            tree: tree,
            stuffedData: stuffedData,
            srcPtr: srcPtr,
            bitPos: bitPos
          };
        },

        readHuffman: function(input, data, OutPixelTypeArray) {
          var headerInfo = data.headerInfo;
          var numDims = headerInfo.numDims;
          var height = data.headerInfo.height;
          var width = data.headerInfo.width;
          var numPixels = width * height;
          //var size_max = 1 << BITS_MAX;
          /* ************************
           * reading huffman structure info
           *************************/
          var huffmanInfo = this.readHuffmanTree(input, data);
          var decodeLut = huffmanInfo.decodeLut;
          var tree = huffmanInfo.tree;
          //stuffedData includes huffman headers
          var stuffedData = huffmanInfo.stuffedData;
          var srcPtr = huffmanInfo.srcPtr;
          var bitPos = huffmanInfo.bitPos;
          var numBitsLUTQick = huffmanInfo.numBitsLUTQick;
          var numBitsLUT = huffmanInfo.numBitsLUT;
          var offset = data.headerInfo.imageType === 0 ? 128 : 0;
          /*************************
          *  decode
          ***************************/
          var node, val, delta, mask = data.pixels.resultMask, valTmp, valTmpQuick, currentBit;
          var i, j, k, ii;
          var prevVal = 0;
          if (bitPos > 0) {
            srcPtr++;
            bitPos = 0;
          }
          var word = stuffedData[srcPtr];
          var deltaEncode = data.encodeMode === 1;
          var resultPixelsAllDim = new OutPixelTypeArray(numPixels * numDims);
          var resultPixels = resultPixelsAllDim;
          var iDim;
          for (iDim = 0; iDim < headerInfo.numDims; iDim++) {
            if (numDims > 1) {
              //get the mem block of current dimension
              resultPixels = new OutPixelTypeArray(resultPixelsAllDim.buffer, numPixels * iDim, numPixels);
              prevVal = 0;
            }
            if (data.headerInfo.numValidPixel === width * height) { //all valid
              for (k = 0, i = 0; i < height; i++) {
                for (j = 0; j < width; j++, k++) {
                  val = 0;
                  valTmp = (word << bitPos) >>> (32 - numBitsLUTQick);
                  valTmpQuick = valTmp;// >>> deltaBits;
                  if (32 - bitPos < numBitsLUTQick) {
                    valTmp |= ((stuffedData[srcPtr + 1]) >>> (64 - bitPos - numBitsLUTQick));
                    valTmpQuick = valTmp;// >>> deltaBits;
                  }
                  if (decodeLut[valTmpQuick])    // if there, move the correct number of bits and done
                  {
                    val = decodeLut[valTmpQuick][1];
                    bitPos += decodeLut[valTmpQuick][0];
                  }
                  else {
                    valTmp = (word << bitPos) >>> (32 - numBitsLUT);
                    valTmpQuick = valTmp;// >>> deltaBits;
                    if (32 - bitPos < numBitsLUT) {
                      valTmp |= ((stuffedData[srcPtr + 1]) >>> (64 - bitPos - numBitsLUT));
                      valTmpQuick = valTmp;// >>> deltaBits;
                    }
                    node = tree;
                    for (ii = 0; ii < numBitsLUT; ii++) {
                      currentBit = valTmp >>> (numBitsLUT - ii - 1) & 1;
                      node = currentBit ? node.right : node.left;
                      if (!(node.left || node.right)) {
                        val = node.val;
                        bitPos = bitPos + ii + 1;
                        break;
                      }
                    }
                  }

                  if (bitPos >= 32) {
                    bitPos -= 32;
                    srcPtr++;
                    word = stuffedData[srcPtr];
                  }

                  delta = val - offset;
                  if (deltaEncode) {
                    if (j > 0) {
                      delta += prevVal;    // use overflow
                    }
                    else if (i > 0) {
                      delta += resultPixels[k - width];
                    }
                    else {
                      delta += prevVal;
                    }
                    delta &= 0xFF; //overflow
                    resultPixels[k] = delta;//overflow
                    prevVal = delta;
                  }
                  else {
                    resultPixels[k] = delta;
                  }
                }
              }
            }
            else { //not all valid, use mask
              for (k = 0, i = 0; i < height; i++) {
                for (j = 0; j < width; j++, k++) {
                  if (mask[k]) {
                    val = 0;
                    valTmp = (word << bitPos) >>> (32 - numBitsLUTQick);
                    valTmpQuick = valTmp;// >>> deltaBits;
                    if (32 - bitPos < numBitsLUTQick) {
                      valTmp |= ((stuffedData[srcPtr + 1]) >>> (64 - bitPos - numBitsLUTQick));
                      valTmpQuick = valTmp;// >>> deltaBits;
                    }
                    if (decodeLut[valTmpQuick])    // if there, move the correct number of bits and done
                    {
                      val = decodeLut[valTmpQuick][1];
                      bitPos += decodeLut[valTmpQuick][0];
                    }
                    else {
                      valTmp = (word << bitPos) >>> (32 - numBitsLUT);
                      valTmpQuick = valTmp;// >>> deltaBits;
                      if (32 - bitPos < numBitsLUT) {
                        valTmp |= ((stuffedData[srcPtr + 1]) >>> (64 - bitPos - numBitsLUT));
                        valTmpQuick = valTmp;// >>> deltaBits;
                      }
                      node = tree;
                      for (ii = 0; ii < numBitsLUT; ii++) {
                        currentBit = valTmp >>> (numBitsLUT - ii - 1) & 1;
                        node = currentBit ? node.right : node.left;
                        if (!(node.left || node.right)) {
                          val = node.val;
                          bitPos = bitPos + ii + 1;
                          break;
                        }
                      }
                    }

                    if (bitPos >= 32) {
                      bitPos -= 32;
                      srcPtr++;
                      word = stuffedData[srcPtr];
                    }

                    delta = val - offset;
                    if (deltaEncode) {
                      if (j > 0 && mask[k - 1]) {
                        delta += prevVal;    // use overflow
                      }
                      else if (i > 0 && mask[k - width]) {
                        delta += resultPixels[k - width];
                      }
                      else {
                        delta += prevVal;
                      }

                      delta &= 0xFF; //overflow
                      resultPixels[k] = delta;//overflow
                      prevVal = delta;
                    }
                    else {
                      resultPixels[k] = delta;
                    }
                  }
                }
              }
            }
            data.ptr = data.ptr + (srcPtr + 1) * 4 + (bitPos > 0 ? 4 : 0);
          }
          data.pixels.resultPixels = resultPixelsAllDim;
        },

        decodeBits: function(input, data, blockDataBuffer, offset, iDim) {
          {
            //bitstuff encoding is 3
            var headerInfo = data.headerInfo;
            var fileVersion = headerInfo.fileVersion;
            //var block = {};
            var blockPtr = 0;
            var viewByteLength = ((input.byteLength - data.ptr) >= 5) ? 5 : (input.byteLength - data.ptr);
            var view = new DataView(input, data.ptr, viewByteLength);
            var headerByte = view.getUint8(0);
            blockPtr++;
            var bits67 = headerByte >> 6;
            var n = (bits67 === 0) ? 4 : 3 - bits67;
            var doLut = (headerByte & 32) > 0 ? true : false;//5th bit
            var numBits = headerByte & 31;
            var numElements = 0;
            if (n === 1) {
              numElements = view.getUint8(blockPtr); blockPtr++;
            } else if (n === 2) {
              numElements = view.getUint16(blockPtr, true); blockPtr += 2;
            } else if (n === 4) {
              numElements = view.getUint32(blockPtr, true); blockPtr += 4;
            } else {
              throw "Invalid valid pixel count type";
            }
            //fix: huffman codes are bit stuffed, but not bound by data's max value, so need to use originalUnstuff
            //offset = offset || 0;
            var scale = 2 * headerInfo.maxZError;
            var stuffedData, arrayBuf, store8, dataBytes, dataWords;
            var lutArr, lutData, lutBytes, bitsPerPixel;
            var zMax = headerInfo.numDims > 1 ? headerInfo.maxValues[iDim] : headerInfo.zMax;
            if (doLut) {
              data.counter.lut++;
              lutBytes = view.getUint8(blockPtr);
              blockPtr++;
              dataBytes = Math.ceil((lutBytes - 1) * numBits / 8);
              dataWords = Math.ceil(dataBytes / 4);
              arrayBuf = new ArrayBuffer(dataWords * 4);
              store8 = new Uint8Array(arrayBuf);

              data.ptr += blockPtr;
              store8.set(new Uint8Array(input, data.ptr, dataBytes));

              lutData = new Uint32Array(arrayBuf);
              data.ptr += dataBytes;

              bitsPerPixel = 0;
              while ((lutBytes - 1) >>> bitsPerPixel) {
                bitsPerPixel++;
              }
              dataBytes = Math.ceil(numElements * bitsPerPixel / 8);
              dataWords = Math.ceil(dataBytes / 4);
              arrayBuf = new ArrayBuffer(dataWords * 4);
              store8 = new Uint8Array(arrayBuf);
              store8.set(new Uint8Array(input, data.ptr, dataBytes));
              stuffedData = new Uint32Array(arrayBuf);
              data.ptr += dataBytes;
              if (fileVersion >= 3) {
                lutArr = BitStuffer.unstuffLUT2(lutData, numBits, lutBytes - 1, offset, scale, zMax);
              }
              else {
                lutArr = BitStuffer.unstuffLUT(lutData, numBits, lutBytes - 1, offset, scale, zMax);
              }
              //lutArr.unshift(0);
              if (fileVersion >= 3) {
                //BitStuffer.unstuff2(block, blockDataBuffer, headerInfo.zMax);
                BitStuffer.unstuff2(stuffedData, blockDataBuffer, bitsPerPixel, numElements, lutArr);
              }
              else {
                BitStuffer.unstuff(stuffedData, blockDataBuffer, bitsPerPixel, numElements, lutArr);
              }
            }
            else {
              //console.debug("bitstuffer");
              data.counter.bitstuffer++;
              bitsPerPixel = numBits;
              data.ptr += blockPtr;
              if (bitsPerPixel > 0) {
                dataBytes = Math.ceil(numElements * bitsPerPixel / 8);
                dataWords = Math.ceil(dataBytes / 4);
                arrayBuf = new ArrayBuffer(dataWords * 4);
                store8 = new Uint8Array(arrayBuf);
                store8.set(new Uint8Array(input, data.ptr, dataBytes));
                stuffedData = new Uint32Array(arrayBuf);
                data.ptr += dataBytes;
                if (fileVersion >= 3) {
                  if (offset === null) {
                    BitStuffer.originalUnstuff2(stuffedData, blockDataBuffer, bitsPerPixel, numElements);
                  }
                  else {
                    BitStuffer.unstuff2(stuffedData, blockDataBuffer, bitsPerPixel, numElements, false, offset, scale, zMax);
                  }
                }
                else {
                  if (offset === null) {
                    BitStuffer.originalUnstuff(stuffedData, blockDataBuffer, bitsPerPixel, numElements);
                  }
                  else {
                    BitStuffer.unstuff(stuffedData, blockDataBuffer, bitsPerPixel, numElements, false, offset, scale, zMax);
                  }
                }
              }
            }
          }

        },

        readTiles: function(input, data, OutPixelTypeArray) {
          var headerInfo = data.headerInfo;
          var width = headerInfo.width;
          var height = headerInfo.height;
          var microBlockSize = headerInfo.microBlockSize;
          var imageType = headerInfo.imageType;
          var dataTypeSize = Lerc2Helpers.getDataTypeSize(imageType);
          var numBlocksX = Math.ceil(width / microBlockSize);
          var numBlocksY = Math.ceil(height / microBlockSize);
          data.pixels.numBlocksY = numBlocksY;
          data.pixels.numBlocksX = numBlocksX;
          data.pixels.ptr = 0;
          var row = 0, col = 0, blockY = 0, blockX = 0, thisBlockHeight = 0, thisBlockWidth = 0, bytesLeft = 0, headerByte = 0, bits67 = 0, testCode = 0, outPtr = 0, outStride = 0, numBytes = 0, bytesleft = 0, z = 0, blockPtr = 0;
          var view, block, arrayBuf, store8, rawData;
          var blockEncoding;
          var blockDataBuffer = new OutPixelTypeArray(microBlockSize * microBlockSize);
          var lastBlockHeight = (height % microBlockSize) || microBlockSize;
          var lastBlockWidth = (width % microBlockSize) || microBlockSize;
          var offsetType, offset;
          var numDims = headerInfo.numDims, iDim;
          var mask = data.pixels.resultMask;
          var resultPixels = data.pixels.resultPixels;
          for (blockY = 0; blockY < numBlocksY; blockY++) {
            thisBlockHeight = (blockY !== numBlocksY - 1) ? microBlockSize : lastBlockHeight;
            for (blockX = 0; blockX < numBlocksX; blockX++) {
              //console.debug("y" + blockY + " x" + blockX);
              thisBlockWidth = (blockX !== numBlocksX - 1) ? microBlockSize : lastBlockWidth;

              outPtr = blockY * width * microBlockSize + blockX * microBlockSize;
              outStride = width - thisBlockWidth;


              for (iDim = 0; iDim < numDims; iDim++) {
                if (numDims > 1) {
                  resultPixels = new OutPixelTypeArray(data.pixels.resultPixels.buffer, width * height * iDim * dataTypeSize, width * height);
                }
                bytesLeft = input.byteLength - data.ptr;
                view = new DataView(input, data.ptr, Math.min(10, bytesLeft));
                block = {};
                blockPtr = 0;
                headerByte = view.getUint8(0);
                blockPtr++;
                bits67 = (headerByte >> 6) & 0xFF;
                testCode = (headerByte >> 2) & 15;    // use bits 2345 for integrity check
                if (testCode !== (((blockX * microBlockSize) >> 3) & 15)) {
                  throw "integrity issue";
                  //return false;
                }

                blockEncoding = headerByte & 3;
                if (blockEncoding > 3) {
                  data.ptr += blockPtr;
                  throw "Invalid block encoding (" + blockEncoding + ")";
                }
                else if (blockEncoding === 2) { //constant 0
                  data.counter.constant++;
                  data.ptr += blockPtr;
                  continue;
                }
                else if (blockEncoding === 0) {  //uncompressed
                  data.counter.uncompressed++;
                  data.ptr += blockPtr;
                  numBytes = thisBlockHeight * thisBlockWidth * dataTypeSize;
                  bytesleft = input.byteLength - data.ptr;
                  numBytes = numBytes < bytesleft ? numBytes : bytesleft;
                  //bit alignment
                  arrayBuf = new ArrayBuffer((numBytes % dataTypeSize) === 0 ? numBytes : (numBytes + dataTypeSize - numBytes % dataTypeSize));
                  store8 = new Uint8Array(arrayBuf);
                  store8.set(new Uint8Array(input, data.ptr, numBytes));
                  rawData = new OutPixelTypeArray(arrayBuf);
                  z = 0;
                  if (mask) {
                    for (row = 0; row < thisBlockHeight; row++) {
                      for (col = 0; col < thisBlockWidth; col++) {
                        if (mask[outPtr]) {
                          resultPixels[outPtr] = rawData[z++];
                        }
                        outPtr++;
                      }
                      outPtr += outStride;
                    }
                  }
                  else {//all valid
                    for (row = 0; row < thisBlockHeight; row++) {
                      for (col = 0; col < thisBlockWidth; col++) {
                        resultPixels[outPtr++] = rawData[z++];
                      }
                      outPtr += outStride;
                    }
                  }
                  data.ptr += z * dataTypeSize;
                }
                else { //1 or 3
                  offsetType = Lerc2Helpers.getDataTypeUsed(imageType, bits67);
                  offset = Lerc2Helpers.getOnePixel(block, blockPtr, offsetType, view);
                  blockPtr += Lerc2Helpers.getDataTypeSize(offsetType);
                  if (blockEncoding === 3) //constant offset value
                  {
                    data.ptr += blockPtr;
                    data.counter.constantoffset++;
                    //you can delete the following resultMask case in favor of performance because val is constant and users use nodata mask, otherwise nodatavalue post processing handles it too.
                    //while the above statement is true, we're not doing it as we want to keep invalid pixel value at 0 rather than arbitrary values
                    if (mask) {
                      for (row = 0; row < thisBlockHeight; row++) {
                        for (col = 0; col < thisBlockWidth; col++) {
                          if (mask[outPtr]) {
                            resultPixels[outPtr] = offset;
                          }
                          outPtr++;
                        }
                        outPtr += outStride;
                      }
                    }
                    else {
                      for (row = 0; row < thisBlockHeight; row++) {
                        for (col = 0; col < thisBlockWidth; col++) {
                          resultPixels[outPtr++] = offset;
                        }
                        outPtr += outStride;
                      }
                    }
                  }
                  else { //bitstuff encoding is 3
                    data.ptr += blockPtr;
                    //heavy lifting
                    Lerc2Helpers.decodeBits(input, data, blockDataBuffer, offset, iDim);
                    blockPtr = 0;
                    if (mask) {
                      for (row = 0; row < thisBlockHeight; row++) {
                        for (col = 0; col < thisBlockWidth; col++) {
                          if (mask[outPtr]) {
                            resultPixels[outPtr] = blockDataBuffer[blockPtr++];
                          }
                          outPtr++;
                        }
                        outPtr += outStride;
                      }
                    }
                    else {
                      for (row = 0; row < thisBlockHeight; row++) {
                        for (col = 0; col < thisBlockWidth; col++) {
                          resultPixels[outPtr++] = blockDataBuffer[blockPtr++];
                        }
                        outPtr += outStride;
                      }
                    }
                  }
                }
              }
            }
          }
        },

        /*****************
        *  private methods (helper methods)
        *****************/

        formatFileInfo: function(data) {
          return {
            "fileIdentifierString": data.headerInfo.fileIdentifierString,
            "fileVersion": data.headerInfo.fileVersion,
            "imageType": data.headerInfo.imageType,
            "height": data.headerInfo.height,
            "width": data.headerInfo.width,
            "numValidPixel": data.headerInfo.numValidPixel,
            "microBlockSize": data.headerInfo.microBlockSize,
            "blobSize": data.headerInfo.blobSize,
            "maxZError": data.headerInfo.maxZError,
            "pixelType": Lerc2Helpers.getPixelType(data.headerInfo.imageType),
            "eofOffset": data.eofOffset,
            "mask": data.mask ? {
              "numBytes": data.mask.numBytes
            } : null,
            "pixels": {
              "numBlocksX": data.pixels.numBlocksX,
              "numBlocksY": data.pixels.numBlocksY,
              //"numBytes": data.pixels.numBytes,
              "maxValue": data.headerInfo.zMax,
              "minValue": data.headerInfo.zMin,
              "noDataValue": data.noDataValue
            }
          };
        },

        constructConstantSurface: function(data) {
          var val = data.headerInfo.zMax;
          var numDims =  data.headerInfo.numDims;
          var numPixels = data.headerInfo.height * data.headerInfo.width;
          var numPixelAllDims = numPixels * numDims;
          var i=0, k = 0, nStart=0;
          var mask = data.pixels.resultMask;
          if (mask) {
            if (numDims > 1) {
              for (i=0; i < numDims; i++) {
                nStart = i * numPixels;
                for (k = 0; k < numPixels; k++) {
                  if (mask[k]) {
                    data.pixels.resultPixels[nStart + k] = val;
                  }
                }
              }
            }
            else {
              for (k = 0; k < numPixels; k++) {
                if (mask[k]) {
                  data.pixels.resultPixels[k] = val;
                }
              }
            }
          }
          else {
            if (data.pixels.resultPixels.fill) {
              data.pixels.resultPixels.fill(val);
            }
            else {
              for (k = 0; k < numPixelAllDims; k++) {
                data.pixels.resultPixels[k] = val;
              }
            }
          }
          return;
        },

        getDataTypeArray: function(t) {
          var tp;
          switch (t) {
            case 0: //char
              tp = Int8Array;
              break;
            case 1: //byte
              tp = Uint8Array;
              break;
            case 2: //short
              tp = Int16Array;
              break;
            case 3: //ushort
              tp = Uint16Array;
              break;
            case 4:
              tp = Int32Array;
              break;
            case 5:
              tp = Uint32Array;
              break;
            case 6:
              tp = Float32Array;
              break;
            case 7:
              tp = Float64Array;
              break;
            default:
              tp = Float32Array;
          }
          return tp;
        },

        getPixelType: function(t) {
          var tp;
          switch (t) {
            case 0: //char
              tp = "S8";
              break;
            case 1: //byte
              tp = "U8";
              break;
            case 2: //short
              tp = "S16";
              break;
            case 3: //ushort
              tp = "U16";
              break;
            case 4:
              tp = "S32";
              break;
            case 5:
              tp = "U32";
              break;
            case 6:
              tp = "F32";
              break;
            case 7:
              tp = "F64"; //not supported
              break;
            default:
              tp = "F32";
          }
          return tp;
        },

        isValidPixelValue: function(t, val) {
          if (val === null) {
            return false;
          }
          var isValid;
          switch (t) {
            case 0: //char
              isValid = val >= -128 && val <= 127;
              break;
            case 1: //byte  (unsigned char)
              isValid = val >= 0 && val <= 255;
              break;
            case 2: //short
              isValid = val >= -32768 && val <= 32767;
              break;
            case 3: //ushort
              isValid = val >= 0 && val <= 65536;
              break;
            case 4: //int 32
              isValid = val >= -2147483648 && val <= 2147483647;
              break;
            case 5: //uinit 32
              isValid = val >= 0 && val <= 4294967296;
              break;
            case 6:
              isValid = val >= -3.4027999387901484e+38 && val <= 3.4027999387901484e+38;
              break;
            case 7:
              isValid = val >= 5e-324 && val <= 1.7976931348623157e+308;
              break;
            default:
              isValid = false;
          }
          return isValid;
        },

        getDataTypeSize: function(t) {
          var s = 0;
          switch (t) {
            case 0: //ubyte
            case 1: //byte
              s = 1;
              break;
            case 2: //short
            case 3: //ushort
              s = 2;
              break;
            case 4:
            case 5:
            case 6:
              s = 4;
              break;
            case 7:
              s = 8;
              break;
            default:
              s = t;
          }
          return s;
        },

        getDataTypeUsed: function(dt, tc) {
          var t = dt;
          switch (dt) {
            case 2: //short
            case 4: //long
              t = dt - tc;
              break;
            case 3: //ushort
            case 5: //ulong
              t = dt - 2 * tc;
              break;
            case 6: //float
              if (0 === tc) {
                t = dt;
              }
              else if (1 === tc) {
                t = 2;
              }
              else {
                t = 1;//byte
              }
              break;
            case 7: //double
              if (0 === tc) {
                t = dt;
              }
              else {
                t = dt - 2 * tc + 1;
              }
              break;
            default:
              t = dt;
              break;
          }
          return t;
        },

        getOnePixel: function(block, blockPtr, offsetType, view) {
          var temp = 0;
          switch (offsetType) {
            case 0: //char
              temp = view.getInt8(blockPtr);
              break;
            case 1: //byte
              temp = view.getUint8(blockPtr);
              break;
            case 2:
              temp = view.getInt16(blockPtr, true);
              break;
            case 3:
              temp = view.getUint16(blockPtr, true);
              break;
            case 4:
              temp = view.getInt32(blockPtr, true);
              break;
            case 5:
              temp = view.getUInt32(blockPtr, true);
              break;
            case 6:
              temp = view.getFloat32(blockPtr, true);
              break;
            case 7:
              //temp = view.getFloat64(blockPtr, true);
              //blockPtr += 8;
              //lerc2 encoding doesnt handle float 64, force to float32???
              temp = view.getFloat64(blockPtr, true);
              break;
            default:
              throw ("the decoder does not understand this pixel type");
          }
          return temp;
        }
      };

      /***************************************************
      *private class for a tree node. Huffman code is in Lerc2Helpers
      ****************************************************/
      var TreeNode = function(val, left, right) {
        this.val = val;
        this.left = left;
        this.right = right;
      };

      var Lerc2Decode = {
        /*
        * ********removed options compared to LERC1. We can bring some of them back if needed.
         * removed pixel type. LERC2 is typed and doesn't require user to give pixel type
         * changed encodedMaskData to maskData. LERC2 's js version make it faster to use maskData directly.
         * removed returnMask. mask is used by LERC2 internally and is cost free. In case of user input mask, it's returned as well and has neglible cost.
         * removed nodatavalue. Because LERC2 pixels are typed, nodatavalue will sacrify a useful value for many types (8bit, 16bit) etc,
         *       user has to be knowledgable enough about raster and their data to avoid usability issues. so nodata value is simply removed now.
         *       We can add it back later if their's a clear requirement.
         * removed encodedMask. This option was not implemented in LercDecode. It can be done after decoding (less efficient)
         * removed computeUsedBitDepths.
         *
         *
         * response changes compared to LERC1
         * 1. encodedMaskData is not available
         * 2. noDataValue is optional (returns only if user's noDataValue is with in the valid data type range)
         * 3. maskData is always available
        */
        /*****************
        *  public properties
        ******************/
        //HUFFMAN_LUT_BITS_MAX: 12, //use 2^12 lut, not configurable

        /*****************
        *  public methods
        *****************/

        /**
         * Decode a LERC2 byte stream and return an object containing the pixel data and optional metadata.
         *
         * @param {ArrayBuffer} input The LERC input byte stream
         * @param {object} [options] options Decoding options
         * @param {number} [options.inputOffset] The number of bytes to skip in the input byte stream. A valid LERC file is expected at that position
         * @param {boolean} [options.returnFileInfo] If true, the return value will have a fileInfo property that contains metadata obtained from the LERC headers and the decoding process
         */
        decode: function(/*byte array*/ input, /*object*/ options) {
          //currently there's a bug in the sparse array, so please do not set to false
          options = options || {};
          var noDataValue = options.noDataValue;

          //initialize
          var i = 0, data = {};
          data.ptr = options.inputOffset || 0;
          data.pixels = {};

          // File header
          if (!Lerc2Helpers.readHeaderInfo(input, data)) {
            return;
          }
          var headerInfo = data.headerInfo;
          var fileVersion = headerInfo.fileVersion;
          var OutPixelTypeArray = Lerc2Helpers.getDataTypeArray(headerInfo.imageType);

          // Mask Header
          Lerc2Helpers.readMask(input, data);
          if (headerInfo.numValidPixel !== headerInfo.width * headerInfo.height && !data.pixels.resultMask) {
            data.pixels.resultMask = options.maskData;
          }

          var numPixels = headerInfo.width * headerInfo.height;
          data.pixels.resultPixels = new OutPixelTypeArray(numPixels * headerInfo.numDims);

          data.counter = {
            onesweep: 0,
            uncompressed: 0,
            lut: 0,
            bitstuffer: 0,
            constant: 0,
            constantoffset: 0
          };
          if (headerInfo.numValidPixel !== 0) {
            //not tested
            if (headerInfo.zMax === headerInfo.zMin) //constant surface
            {
              Lerc2Helpers.constructConstantSurface(data);
            }
            else if (fileVersion >= 4 && Lerc2Helpers.checkMinMaxRanges(input, data)) {
              Lerc2Helpers.constructConstantSurface(data);
            }
            else {
              var view = new DataView(input, data.ptr, 2);
              var bReadDataOneSweep = view.getUint8(0);
              data.ptr++;
              if (bReadDataOneSweep) {
                //console.debug("OneSweep");
                Lerc2Helpers.readDataOneSweep(input, data, OutPixelTypeArray);
              }
              else {
                //lerc2.1: //bitstuffing + lut
                //lerc2.2: //bitstuffing + lut + huffman
                //lerc2.3: new bitstuffer
                if (fileVersion > 1 && headerInfo.imageType <= 1 && Math.abs(headerInfo.maxZError - 0.5) < 0.00001) {
                  //this is 2.x plus 8 bit (unsigned and signed) data, possiblity of Huffman
                  var flagHuffman = view.getUint8(1);
                  data.ptr++;
                  data.encodeMode = flagHuffman;
                  if (flagHuffman > 2 || (fileVersion < 4 && flagHuffman > 1)) {
                    throw "Invalid Huffman flag " + flagHuffman;
                  }
                  if (flagHuffman) {//1 - delta Huffman, 2 - Huffman
                    //console.log("Huffman");
                    Lerc2Helpers.readHuffman(input, data, OutPixelTypeArray);
                  }
                  else {
                    //console.log("Tiles");
                    Lerc2Helpers.readTiles(input, data, OutPixelTypeArray);
                  }
                }
                else { //lerc2.x non-8 bit data
                  //console.log("Tiles");
                  Lerc2Helpers.readTiles(input, data, OutPixelTypeArray);
                }
              }
            }
          }

          data.eofOffset = data.ptr;
          var diff;
          if (options.inputOffset) {
            diff = data.headerInfo.blobSize + options.inputOffset - data.ptr;
            if (Math.abs(diff) >= 1) {
              //console.debug("incorrect eof: dataptr " + data.ptr + " offset " + options.inputOffset + " blobsize " + data.headerInfo.blobSize + " diff: " + diff);
              data.eofOffset = options.inputOffset + data.headerInfo.blobSize;
            }
          }
          else {
            diff = data.headerInfo.blobSize - data.ptr;
            if (Math.abs(diff) >= 1) {
              //console.debug("incorrect first band eof: dataptr " + data.ptr + " blobsize " + data.headerInfo.blobSize + " diff: " + diff);
              data.eofOffset = data.headerInfo.blobSize;
            }
          }

          var result = {
            width: headerInfo.width,
            height: headerInfo.height,
            pixelData: data.pixels.resultPixels,
            minValue: headerInfo.zMin,
            maxValue: headerInfo.zMax,
            validPixelCount: headerInfo.numValidPixel,
            dimCount: headerInfo.numDims,
            dimStats: {
              minValues: headerInfo.minValues,
              maxValues: headerInfo.maxValues
            },
            maskData: data.pixels.resultMask
            //noDataValue: noDataValue
          };

          //we should remove this if there's no existing client
          //optional noDataValue processing, it's user's responsiblity
          if (data.pixels.resultMask && Lerc2Helpers.isValidPixelValue(headerInfo.imageType, noDataValue)) {
            var mask = data.pixels.resultMask;
            for (i = 0; i < numPixels; i++) {
              if (!mask[i]) {
                result.pixelData[i] = noDataValue;
              }
            }
            result.noDataValue = noDataValue;
          }
          data.noDataValue = noDataValue;
          if (options.returnFileInfo) {
            result.fileInfo = Lerc2Helpers.formatFileInfo(data);
          }
          return result;
        },

        getBandCount: function(/*byte array*/ input) {
          var count = 0;
          var i = 0;
          var temp = {};
          temp.ptr = 0;
          temp.pixels = {};
          while (i < input.byteLength - 58) {
            Lerc2Helpers.readHeaderInfo(input, temp);
            i += temp.headerInfo.blobSize;
            count++;
            temp.ptr = i;
          }
          return count;
        }
      };

      return Lerc2Decode;
    })();

    var isPlatformLittleEndian = (function() {
      var a = new ArrayBuffer(4);
      var b = new Uint8Array(a);
      var c = new Uint32Array(a);
      c[0] = 1;
      return b[0] === 1;
    })();

    var Lerc = {
      /************wrapper**********************************************/
      /**
       * A wrapper for decoding both LERC1 and LERC2 byte streams capable of handling multiband pixel blocks for various pixel types.
       *
       * @alias module:Lerc
       * @param {ArrayBuffer} input The LERC input byte stream
       * @param {object} [options] The decoding options below are optional.
       * @param {number} [options.inputOffset] The number of bytes to skip in the input byte stream. A valid Lerc file is expected at that position.
       * @param {string} [options.pixelType] (LERC1 only) Default value is F32. Valid pixel types for input are U8/S8/S16/U16/S32/U32/F32.
       * @param {number} [options.noDataValue] (LERC1 only). It is recommended to use the returned mask instead of setting this value.
       * @returns {{width, height, pixels, pixelType, mask, statistics}}
         * @property {number} width Width of decoded image.
         * @property {number} height Height of decoded image.
         * @property {array} pixels [band1, band2, …] Each band is a typed array of width*height.
         * @property {string} pixelType The type of pixels represented in the output.
         * @property {mask} mask Typed array with a size of width*height, or null if all pixels are valid.
         * @property {array} statistics [statistics_band1, statistics_band2, …] Each element is a statistics object representing min and max values
      **/
      decode: function(encodedData, options) {
        if (!isPlatformLittleEndian) {
          throw "Big endian system is not supported.";
        }
        options = options || {};
        var inputOffset = options.inputOffset || 0;
        var fileIdView = new Uint8Array(encodedData, inputOffset, 10);
        var fileIdentifierString = String.fromCharCode.apply(null, fileIdView);
        var lerc, majorVersion;
        if (fileIdentifierString.trim() === "CntZImage") {
          lerc = LercDecode;
          majorVersion = 1;
        }
        else if (fileIdentifierString.substring(0, 5) === "Lerc2") {
          lerc = Lerc2Decode;
          majorVersion = 2;
        }
        else {
          throw "Unexpected file identifier string: " + fileIdentifierString;
        }

        var iPlane = 0, eof = encodedData.byteLength - 10, encodedMaskData, bandMasks = [], bandMask, maskData;
        var decodedPixelBlock = {
          width: 0,
          height: 0,
          pixels: [],
          pixelType: options.pixelType,
          mask: null,
          statistics: []
        };

        while (inputOffset < eof) {
          var result = lerc.decode(encodedData, {
            inputOffset: inputOffset,//for both lerc1 and lerc2
            encodedMaskData: encodedMaskData,//lerc1 only
            maskData: maskData,//lerc2 only
            returnMask: iPlane === 0 ? true : false,//lerc1 only
            returnEncodedMask: iPlane === 0 ? true : false,//lerc1 only
            returnFileInfo: true,//for both lerc1 and lerc2
            pixelType: options.pixelType || null,//lerc1 only
            noDataValue: options.noDataValue || null//lerc1 only
          });

          inputOffset = result.fileInfo.eofOffset;
          if (iPlane === 0) {
            encodedMaskData = result.encodedMaskData;//lerc1
            maskData = result.maskData;//lerc2
            decodedPixelBlock.width = result.width;
            decodedPixelBlock.height = result.height;
            decodedPixelBlock.dimCount = result.dimCount || 1;
            //decodedPixelBlock.dimStats = decodedPixelBlock.dimStats;
            decodedPixelBlock.pixelType = result.pixelType || result.fileInfo.pixelType;
            decodedPixelBlock.mask = result.maskData;
          }
          if (majorVersion >1 && result.fileInfo.mask && result.fileInfo.mask.numBytes > 0) {
            bandMasks.push(result.maskData);
          }

          iPlane++;
          decodedPixelBlock.pixels.push(result.pixelData);
          decodedPixelBlock.statistics.push({
            minValue: result.minValue,
            maxValue: result.maxValue,
            noDataValue: result.noDataValue,
            dimStats: result.dimStats
          });
        }
        var i, j, numPixels;
        if (majorVersion > 1 && bandMasks.length > 1) {
          numPixels = decodedPixelBlock.width * decodedPixelBlock.height;
          decodedPixelBlock.bandMasks = bandMasks;
          maskData = new Uint8Array(numPixels);
          maskData.set(bandMasks[0]);
          for (i = 1; i < bandMasks.length; i++) {
            bandMask = bandMasks[i];
            for (j = 0; j < numPixels; j++) {
              maskData[j] = maskData[j] & bandMask[j];
            }
          }
          decodedPixelBlock.maskData = maskData;
        }

        return decodedPixelBlock;
      }
    };

    tmp$6.Lerc = Lerc;
  })();

  var LercDecode = tmp$6.Lerc;

  var tmp$7 = {};

  /*! NoSleep.js v0.9.0 - git.io/vfn01 - Rich Tibbett - MIT license */
  (function webpackUniversalModuleDefinition(root, factory) {
  	// if(typeof exports === 'object' && typeof module === 'object')
  	// 	module.exports = factory();
  	// else if(typeof define === 'function' && define.amd)
  	// 	define([], factory);
  	// else if(typeof exports === 'object')
  	// 	exports["NoSleep"] = factory();
  	// else
  		root["NoSleep"] = factory();
  })(tmp$7, function() {
  return /******/ (function(modules) { // webpackBootstrap
  /******/ 	// The module cache
  /******/ 	var installedModules = {};
  /******/
  /******/ 	// The require function
  /******/ 	function __webpack_require__(moduleId) {
  /******/
  /******/ 		// Check if module is in cache
  /******/ 		if(installedModules[moduleId]) {
  /******/ 			return installedModules[moduleId].exports;
  /******/ 		}
  /******/ 		// Create a new module (and put it into the cache)
  /******/ 		var module = installedModules[moduleId] = {
  /******/ 			i: moduleId,
  /******/ 			l: false,
  /******/ 			exports: {}
  /******/ 		};
  /******/
  /******/ 		// Execute the module function
  /******/ 		modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
  /******/
  /******/ 		// Flag the module as loaded
  /******/ 		module.l = true;
  /******/
  /******/ 		// Return the exports of the module
  /******/ 		return module.exports;
  /******/ 	}
  /******/
  /******/
  /******/ 	// expose the modules object (__webpack_modules__)
  /******/ 	__webpack_require__.m = modules;
  /******/
  /******/ 	// expose the module cache
  /******/ 	__webpack_require__.c = installedModules;
  /******/
  /******/ 	// define getter function for harmony exports
  /******/ 	__webpack_require__.d = function(exports, name, getter) {
  /******/ 		if(!__webpack_require__.o(exports, name)) {
  /******/ 			Object.defineProperty(exports, name, {
  /******/ 				configurable: false,
  /******/ 				enumerable: true,
  /******/ 				get: getter
  /******/ 			});
  /******/ 		}
  /******/ 	};
  /******/
  /******/ 	// getDefaultExport function for compatibility with non-harmony modules
  /******/ 	__webpack_require__.n = function(module) {
  /******/ 		var getter = module && module.__esModule ?
  /******/ 			function getDefault() { return module['default']; } :
  /******/ 			function getModuleExports() { return module; };
  /******/ 		__webpack_require__.d(getter, 'a', getter);
  /******/ 		return getter;
  /******/ 	};
  /******/
  /******/ 	// Object.prototype.hasOwnProperty.call
  /******/ 	__webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };
  /******/
  /******/ 	// __webpack_public_path__
  /******/ 	__webpack_require__.p = "";
  /******/
  /******/ 	// Load entry module and return exports
  /******/ 	return __webpack_require__(__webpack_require__.s = 0);
  /******/ })
  /************************************************************************/
  /******/ ([
  /* 0 */
  /***/ (function(module, exports, __webpack_require__) {


  var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

  function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

  var _require = __webpack_require__(1),
      webm = _require.webm,
      mp4 = _require.mp4;

  // Detect iOS browsers < version 10


  var oldIOS = typeof navigator !== 'undefined' && parseFloat(('' + (/CPU.*OS ([0-9_]{3,4})[0-9_]{0,1}|(CPU like).*AppleWebKit.*Mobile/i.exec(navigator.userAgent) || [0, ''])[1]).replace('undefined', '3_2').replace('_', '.').replace('_', '')) < 10 && !window.MSStream;

  var NoSleep = function () {
    function NoSleep() {
      var _this = this;

      _classCallCheck(this, NoSleep);

      if (oldIOS) {
        this.noSleepTimer = null;
      } else {
        // Set up no sleep video element
        this.noSleepVideo = document.createElement('video');

        this.noSleepVideo.setAttribute('muted', '');
        this.noSleepVideo.setAttribute('title', 'No Sleep');
        this.noSleepVideo.setAttribute('playsinline', '');

        this._addSourceToVideo(this.noSleepVideo, 'webm', webm);
        this._addSourceToVideo(this.noSleepVideo, 'mp4', mp4);

        this.noSleepVideo.addEventListener('loadedmetadata', function () {
          if (_this.noSleepVideo.duration <= 1) {
            // webm source
            _this.noSleepVideo.setAttribute('loop', '');
          } else {
            // mp4 source
            _this.noSleepVideo.addEventListener('timeupdate', function () {
              if (_this.noSleepVideo.currentTime > 0.5) {
                _this.noSleepVideo.currentTime = Math.random();
              }
            });
          }
        });
      }
    }

    _createClass(NoSleep, [{
      key: '_addSourceToVideo',
      value: function _addSourceToVideo(element, type, dataURI) {
        var source = document.createElement('source');
        source.src = dataURI;
        source.type = 'video/' + type;
        element.appendChild(source);
      }
    }, {
      key: 'enable',
      value: function enable() {
        if (oldIOS) {
          this.disable();
          console.warn('\n        NoSleep enabled for older iOS devices. This can interrupt\n        active or long-running network requests from completing successfully.\n        See https://github.com/richtr/NoSleep.js/issues/15 for more details.\n      ');
          this.noSleepTimer = window.setInterval(function () {
            if (!document.hidden) {
              window.location.href = window.location.href.split('#')[0];
              window.setTimeout(window.stop, 0);
            }
          }, 15000);
        } else {
          this.noSleepVideo.play();
        }
      }
    }, {
      key: 'disable',
      value: function disable() {
        if (oldIOS) {
          if (this.noSleepTimer) {
            console.warn('\n          NoSleep now disabled for older iOS devices.\n        ');
            window.clearInterval(this.noSleepTimer);
            this.noSleepTimer = null;
          }
        } else {
          this.noSleepVideo.pause();
        }
      }
    }]);

    return NoSleep;
  }();

  module.exports = NoSleep;

  /***/ }),
  /* 1 */
  /***/ (function(module, exports, __webpack_require__) {


  module.exports = {
    webm: 'data:video/webm;base64,GkXfo0AgQoaBAUL3gQFC8oEEQvOBCEKCQAR3ZWJtQoeBAkKFgQIYU4BnQI0VSalmQCgq17FAAw9CQE2AQAZ3aGFtbXlXQUAGd2hhbW15RIlACECPQAAAAAAAFlSua0AxrkAu14EBY8WBAZyBACK1nEADdW5khkAFVl9WUDglhohAA1ZQOIOBAeBABrCBCLqBCB9DtnVAIueBAKNAHIEAAIAwAQCdASoIAAgAAUAmJaQAA3AA/vz0AAA=',
    mp4: 'data:video/mp4;base64,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  };

  /***/ })
  /******/ ]);
  });

  var NoSleep = tmp$7.NoSleep;

  var oldValue;
  if (typeof ko !== 'undefined') {
      oldValue = ko;
  }

  (function(){
  /*!
   * Knockout JavaScript library v3.5.1
   * (c) The Knockout.js team - http://knockoutjs.com/
   * License: MIT (http://www.opensource.org/licenses/mit-license.php)
   */

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  })();

  // Avoid polluting the global scope.
  var knockout = ko;
  if (typeof window !== 'undefined') {
      ko = window.ko;
      if (typeof oldValue !== 'undefined') {
          window.ko = oldValue;
      } else {
          delete window.ko;
      }
  } else {
      ko = global.ko;
      if (typeof oldValue !== 'undefined') {
          global.ko = oldValue;
      } else {
          delete global.ko;
      }
  }

  /**
   * @license
   * Knockout ES5 plugin - https://github.com/SteveSanderson/knockout-es5
   * Copyright (c) Steve Sanderson
   * MIT license
   */

      var OBSERVABLES_PROPERTY = '__knockoutObservables';
      var SUBSCRIBABLE_PROPERTY = '__knockoutSubscribable';

      // Model tracking
      // --------------
      //
      // This is the central feature of Knockout-ES5. We augment model objects by converting properties
      // into ES5 getter/setter pairs that read/write an underlying Knockout observable. This means you can
      // use plain JavaScript syntax to read/write the property while still getting the full benefits of
      // Knockout's automatic dependency detection and notification triggering.
      //
      // For comparison, here's Knockout ES3-compatible syntax:
      //
      //     var firstNameLength = myModel.user().firstName().length; // Read
      //     myModel.user().firstName('Bert'); // Write
      //
      // ... versus Knockout-ES5 syntax:
      //
      //     var firstNameLength = myModel.user.firstName.length; // Read
      //     myModel.user.firstName = 'Bert'; // Write

      // `ko.track(model)` converts each property on the given model object into a getter/setter pair that
      // wraps a Knockout observable. Optionally specify an array of property names to wrap; otherwise we
      // wrap all properties. If any of the properties are already observables, we replace them with
      // ES5 getter/setter pairs that wrap your original observable instances. In the case of readonly
      // ko.computed properties, we simply do not define a setter (so attempted writes will be ignored,
      // which is how ES5 readonly properties normally behave).
      //
      // By design, this does *not* recursively walk child object properties, because making literally
      // everything everywhere independently observable is usually unhelpful. When you do want to track
      // child object properties independently, define your own class for those child objects and put
      // a separate ko.track call into its constructor --- this gives you far more control.
      function track(obj, propertyNames) {
          if (!obj /*|| typeof obj !== 'object'*/) {
              throw new Error('When calling ko.track, you must pass an object as the first parameter.');
          }

          var ko = this,
              allObservablesForObject = getAllObservablesForObject(obj, true);
          propertyNames = propertyNames || Object.getOwnPropertyNames(obj);

          propertyNames.forEach(function(propertyName) {
              // Skip storage properties
              if (propertyName === OBSERVABLES_PROPERTY || propertyName === SUBSCRIBABLE_PROPERTY) {
                  return;
              }
              // Skip properties that are already tracked
              if (propertyName in allObservablesForObject) {
                  return;
              }

              var origValue = obj[propertyName],
                  isArray = origValue instanceof Array,
                  observable = ko.isObservable(origValue) ? origValue
                                                : isArray ? ko.observableArray(origValue)
                                                          : ko.observable(origValue);

              Object.defineProperty(obj, propertyName, {
                  configurable: true,
                  enumerable: true,
                  get: observable,
                  set: ko.isWriteableObservable(observable) ? observable : undefined
              });

              allObservablesForObject[propertyName] = observable;

              if (isArray) {
                  notifyWhenPresentOrFutureArrayValuesMutate(ko, observable);
              }
          });

          return obj;
      }

      // Gets or creates the hidden internal key-value collection of observables corresponding to
      // properties on the model object.
      function getAllObservablesForObject(obj, createIfNotDefined) {
          var result = obj[OBSERVABLES_PROPERTY];
          if (!result && createIfNotDefined) {
              result = {};
              Object.defineProperty(obj, OBSERVABLES_PROPERTY, {
                  value : result
              });
          }
          return result;
      }

      // Computed properties
      // -------------------
      //
      // The preceding code is already sufficient to upgrade ko.computed model properties to ES5
      // getter/setter pairs (or in the case of readonly ko.computed properties, just a getter).
      // These then behave like a regular property with a getter function, except they are smarter:
      // your evaluator is only invoked when one of its dependencies changes. The result is cached
      // and used for all evaluations until the next time a dependency changes).
      //
      // However, instead of forcing developers to declare a ko.computed property explicitly, it's
      // nice to offer a utility function that declares a computed getter directly.

      // Implements `ko.defineProperty`
      function defineComputedProperty(obj, propertyName, evaluatorOrOptions) {
          var ko = this,
              computedOptions = { owner: obj, deferEvaluation: true };

          if (typeof evaluatorOrOptions === 'function') {
              computedOptions.read = evaluatorOrOptions;
          } else {
              if ('value' in evaluatorOrOptions) {
                  throw new Error('For ko.defineProperty, you must not specify a "value" for the property. You must provide a "get" function.');
              }

              if (typeof evaluatorOrOptions.get !== 'function') {
                  throw new Error('For ko.defineProperty, the third parameter must be either an evaluator function, or an options object containing a function called "get".');
              }

              computedOptions.read = evaluatorOrOptions.get;
              computedOptions.write = evaluatorOrOptions.set;
          }

          obj[propertyName] = ko.computed(computedOptions);
          track.call(ko, obj, [propertyName]);
          return obj;
      }

      // Array handling
      // --------------
      //
      // Arrays are special, because unlike other property types, they have standard mutator functions
      // (`push`/`pop`/`splice`/etc.) and it's desirable to trigger a change notification whenever one of
      // those mutator functions is invoked.
      //
      // Traditionally, Knockout handles this by putting special versions of `push`/`pop`/etc. on observable
      // arrays that mutate the underlying array and then trigger a notification. That approach doesn't
      // work for Knockout-ES5 because properties now return the underlying arrays, so the mutator runs
      // in the context of the underlying array, not any particular observable:
      //
      //     // Operates on the underlying array value
      //     myModel.someCollection.push('New value');
      //
      // To solve this, Knockout-ES5 detects array values, and modifies them as follows:
      //  1. Associates a hidden subscribable with each array instance that it encounters
      //  2. Intercepts standard mutators (`push`/`pop`/etc.) and makes them trigger the subscribable
      // Then, for model properties whose values are arrays, the property's underlying observable
      // subscribes to the array subscribable, so it can trigger a change notification after mutation.

      // Given an observable that underlies a model property, watch for any array value that might
      // be assigned as the property value, and hook into its change events
      function notifyWhenPresentOrFutureArrayValuesMutate(ko, observable) {
          var watchingArraySubscription = null;
          ko.computed(function () {
              // Unsubscribe to any earlier array instance
              if (watchingArraySubscription) {
                  watchingArraySubscription.dispose();
                  watchingArraySubscription = null;
              }

              // Subscribe to the new array instance
              var newArrayInstance = observable();
              if (newArrayInstance instanceof Array) {
                  watchingArraySubscription = startWatchingArrayInstance(ko, observable, newArrayInstance);
              }
          });
      }

      // Listens for array mutations, and when they happen, cause the observable to fire notifications.
      // This is used to make model properties of type array fire notifications when the array changes.
      // Returns a subscribable that can later be disposed.
      function startWatchingArrayInstance(ko, observable, arrayInstance) {
          var subscribable = getSubscribableForArray(ko, arrayInstance);
          return subscribable.subscribe(observable);
      }

      // Gets or creates a subscribable that fires after each array mutation
      function getSubscribableForArray(ko, arrayInstance) {
          var subscribable = arrayInstance[SUBSCRIBABLE_PROPERTY];
          if (!subscribable) {
              subscribable = new ko.subscribable();
              Object.defineProperty(arrayInstance, SUBSCRIBABLE_PROPERTY, {
                  value : subscribable
              });

              var notificationPauseSignal = {};
              wrapStandardArrayMutators(arrayInstance, subscribable, notificationPauseSignal);
              addKnockoutArrayMutators(ko, arrayInstance, subscribable, notificationPauseSignal);
          }

          return subscribable;
      }

      // After each array mutation, fires a notification on the given subscribable
      function wrapStandardArrayMutators(arrayInstance, subscribable, notificationPauseSignal) {
          ['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'].forEach(function(fnName) {
              var origMutator = arrayInstance[fnName];
              arrayInstance[fnName] = function() {
                  var result = origMutator.apply(this, arguments);
                  if (notificationPauseSignal.pause !== true) {
                      subscribable.notifySubscribers(this);
                  }
                  return result;
              };
          });
      }

      // Adds Knockout's additional array mutation functions to the array
      function addKnockoutArrayMutators(ko, arrayInstance, subscribable, notificationPauseSignal) {
          ['remove', 'removeAll', 'destroy', 'destroyAll', 'replace'].forEach(function(fnName) {
              // Make it a non-enumerable property for consistency with standard Array functions
              Object.defineProperty(arrayInstance, fnName, {
                  enumerable: false,
                  value: function() {
                      var result;

                      // These additional array mutators are built using the underlying push/pop/etc.
                      // mutators, which are wrapped to trigger notifications. But we don't want to
                      // trigger multiple notifications, so pause the push/pop/etc. wrappers and
                      // delivery only one notification at the end of the process.
                      notificationPauseSignal.pause = true;
                      try {
                          // Creates a temporary observableArray that can perform the operation.
                          result = ko.observableArray.fn[fnName].apply(ko.observableArray(arrayInstance), arguments);
                      }
                      finally {
                          notificationPauseSignal.pause = false;
                      }
                      subscribable.notifySubscribers(arrayInstance);
                      return result;
                  }
              });
          });
      }

      // Static utility functions
      // ------------------------
      //
      // Since Knockout-ES5 sets up properties that return values, not observables, you can't
      // trivially subscribe to the underlying observables (e.g., `someProperty.subscribe(...)`),
      // or tell them that object values have mutated, etc. To handle this, we set up some
      // extra utility functions that can return or work with the underlying observables.

      // Returns the underlying observable associated with a model property (or `null` if the
      // model or property doesn't exist, or isn't associated with an observable). This means
      // you can subscribe to the property, e.g.:
      //
      //     ko.getObservable(model, 'propertyName')
      //       .subscribe(function(newValue) { ... });
      function getObservable(obj, propertyName) {
          if (!obj /*|| typeof obj !== 'object'*/) {
              return null;
          }

          var allObservablesForObject = getAllObservablesForObject(obj, false);
          return (allObservablesForObject && allObservablesForObject[propertyName]) || null;
      }

      // Causes a property's associated observable to fire a change notification. Useful when
      // the property value is a complex object and you've modified a child property.
      function valueHasMutated(obj, propertyName) {
          var observable = getObservable(obj, propertyName);

          if (observable) {
              observable.valueHasMutated();
          }
      }

      // Extends a Knockout instance with Knockout-ES5 functionality
      function attachToKo(ko) {
          ko.track = track;
          ko.getObservable = getObservable;
          ko.valueHasMutated = valueHasMutated;
          ko.defineProperty = defineComputedProperty;
      }

      var knockout_es5 = {
          attachToKo : attachToKo
      };

  var svgNS = "http://www.w3.org/2000/svg";
  var svgClassName = "cesium-svgPath-svg";

  /**
   * A Knockout binding handler that creates a DOM element for a single SVG path.
   * This binding handler will be registered as cesiumSvgPath.
   *
   * <p>
   * The parameter to this binding is an object with the following properties:
   * </p>
   *
   * <ul>
   * <li>path: The SVG path as a string.</li>
   * <li>width: The width of the SVG path with no transformations applied.</li>
   * <li>height: The height of the SVG path with no transformations applied.</li>
   * <li>css: Optional. A string containing additional CSS classes to apply to the SVG. 'cesium-svgPath-svg' is always applied.</li>
   * </ul>
   *
   * @namespace SvgPathBindingHandler
   *
   * @example
   * // Create an SVG as a child of a div
   * <div data-bind="cesiumSvgPath: { path: 'M 100 100 L 300 100 L 200 300 z', width: 28, height: 28 }"></div>
   *
   * // parameters can be observable from the view model
   * <div data-bind="cesiumSvgPath: { path: currentPath, width: currentWidth, height: currentHeight }"></div>
   *
   * // or the whole object can be observable from the view model
   * <div data-bind="cesiumSvgPath: svgPathOptions"></div>
   */
  var SvgPathBindingHandler = {
    /**
     * @function
     */
    register: function (knockout) {
      knockout.bindingHandlers.cesiumSvgPath = {
        init: function (element, valueAccessor) {
          var svg = document.createElementNS(svgNS, "svg:svg");
          svg.setAttribute("class", svgClassName);

          var pathElement = document.createElementNS(svgNS, "path");
          svg.appendChild(pathElement);

          knockout.virtualElements.setDomNodeChildren(element, [svg]);

          knockout.computed({
            read: function () {
              var value = knockout.unwrap(valueAccessor());

              pathElement.setAttribute("d", knockout.unwrap(value.path));

              var pathWidth = knockout.unwrap(value.width);
              var pathHeight = knockout.unwrap(value.height);

              svg.setAttribute("width", pathWidth);
              svg.setAttribute("height", pathHeight);
              svg.setAttribute("viewBox", "0 0 " + pathWidth + " " + pathHeight);

              if (value.css) {
                svg.setAttribute(
                  "class",
                  svgClassName + " " + knockout.unwrap(value.css)
                );
              }
            },
            disposeWhenNodeIsRemoved: element,
          });

          return {
            controlsDescendantBindings: true,
          };
        },
      };

      knockout.virtualElements.allowedBindings.cesiumSvgPath = true;
    },
  };

  // install the Knockout-ES5 plugin
  knockout_es5.attachToKo(knockout);

  // Register all Cesium binding handlers
  SvgPathBindingHandler.register(knockout);

  function quickselect$1(arr, k, left, right, compare) {
      quickselectStep$1(arr, k, left || 0, right || (arr.length - 1), compare || defaultCompare$1);
  }
  function quickselectStep$1(arr, k, left, right, compare) {

      while (right > left) {
          if (right - left > 600) {
              var n = right - left + 1;
              var m = k - left + 1;
              var z = Math.log(n);
              var s = 0.5 * Math.exp(2 * z / 3);
              var sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1);
              var newLeft = Math.max(left, Math.floor(k - m * s / n + sd));
              var newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd));
              quickselectStep$1(arr, k, newLeft, newRight, compare);
          }

          var t = arr[k];
          var i = left;
          var j = right;

          swap$3(arr, left, k);
          if (compare(arr[right], t) > 0) swap$3(arr, left, right);

          while (i < j) {
              swap$3(arr, i, j);
              i++;
              j--;
              while (compare(arr[i], t) < 0) i++;
              while (compare(arr[j], t) > 0) j--;
          }

          if (compare(arr[left], t) === 0) swap$3(arr, left, j);
          else {
              j++;
              swap$3(arr, j, right);
          }

          if (j <= k) left = j + 1;
          if (k <= j) right = j - 1;
      }
  }

  function swap$3(arr, i, j) {
      var tmp = arr[i];
      arr[i] = arr[j];
      arr[j] = tmp;
  }

  function defaultCompare$1(a, b) {
      return a < b ? -1 : a > b ? 1 : 0;
  }

  /**
   * A view model which exposes a {@link Clock} for user interfaces.
   * @alias ClockViewModel
   * @constructor
   *
   * @param {Clock} [clock] The clock object wrapped by this view model, if undefined a new instance will be created.
   *
   * @see Clock
   */
  function ClockViewModel(clock) {
    if (!defined(clock)) {
      clock = new Clock();
    }
    this._clock = clock;

    this._eventHelper = new EventHelper();
    this._eventHelper.add(clock.onTick, this.synchronize, this);

    /**
     * Gets the current system time.
     * This property is observable.
     * @type {JulianDate}
     */
    this.systemTime = knockout.observable(JulianDate.now());
    this.systemTime.equalityComparer = JulianDate.equals;

    /**
     * Gets or sets the start time of the clock.
     * See {@link Clock#startTime}.
     * This property is observable.
     * @type {JulianDate}
     */
    this.startTime = knockout.observable(clock.startTime);
    this.startTime.equalityComparer = JulianDate.equals;
    this.startTime.subscribe(function (value) {
      clock.startTime = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets the stop time of the clock.
     * See {@link Clock#stopTime}.
     * This property is observable.
     * @type {JulianDate}
     */
    this.stopTime = knockout.observable(clock.stopTime);
    this.stopTime.equalityComparer = JulianDate.equals;
    this.stopTime.subscribe(function (value) {
      clock.stopTime = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets the current time.
     * See {@link Clock#currentTime}.
     * This property is observable.
     * @type {JulianDate}
     */
    this.currentTime = knockout.observable(clock.currentTime);
    this.currentTime.equalityComparer = JulianDate.equals;
    this.currentTime.subscribe(function (value) {
      clock.currentTime = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets the clock multiplier.
     * See {@link Clock#multiplier}.
     * This property is observable.
     * @type {Number}
     */
    this.multiplier = knockout.observable(clock.multiplier);
    this.multiplier.subscribe(function (value) {
      clock.multiplier = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets the clock step setting.
     * See {@link Clock#clockStep}.
     * This property is observable.
     * @type {ClockStep}
     */
    this.clockStep = knockout.observable(clock.clockStep);
    this.clockStep.subscribe(function (value) {
      clock.clockStep = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets the clock range setting.
     * See {@link Clock#clockRange}.
     * This property is observable.
     * @type {ClockRange}
     */
    this.clockRange = knockout.observable(clock.clockRange);
    this.clockRange.subscribe(function (value) {
      clock.clockRange = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets whether the clock can animate.
     * See {@link Clock#canAnimate}.
     * This property is observable.
     * @type {Boolean}
     */
    this.canAnimate = knockout.observable(clock.canAnimate);
    this.canAnimate.subscribe(function (value) {
      clock.canAnimate = value;
      this.synchronize();
    }, this);

    /**
     * Gets or sets whether the clock should animate.
     * See {@link Clock#shouldAnimate}.
     * This property is observable.
     * @type {Boolean}
     */
    this.shouldAnimate = knockout.observable(clock.shouldAnimate);
    this.shouldAnimate.subscribe(function (value) {
      clock.shouldAnimate = value;
      this.synchronize();
    }, this);

    knockout.track(this, [
      "systemTime",
      "startTime",
      "stopTime",
      "currentTime",
      "multiplier",
      "clockStep",
      "clockRange",
      "canAnimate",
      "shouldAnimate",
    ]);
  }

  Object.defineProperties(ClockViewModel.prototype, {
    /**
     * Gets the underlying Clock.
     * @memberof ClockViewModel.prototype
     * @type {Clock}
     */
    clock: {
      get: function () {
        return this._clock;
      },
    },
  });

  /**
   * Updates the view model with the contents of the underlying clock.
   * Can be called to force an update of the viewModel if the underlying
   * clock has changed and <code>Clock.tick</code> has not yet been called.
   */
  ClockViewModel.prototype.synchronize = function () {
    var clock = this._clock;

    this.systemTime = JulianDate.now();
    this.startTime = clock.startTime;
    this.stopTime = clock.stopTime;
    this.currentTime = clock.currentTime;
    this.multiplier = clock.multiplier;
    this.clockStep = clock.clockStep;
    this.clockRange = clock.clockRange;
    this.canAnimate = clock.canAnimate;
    this.shouldAnimate = clock.shouldAnimate;
  };

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  ClockViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the view model.  Should be called to
   * properly clean up the view model when it is no longer needed.
   */
  ClockViewModel.prototype.destroy = function () {
    this._eventHelper.removeAll();

    destroyObject(this);
  };

  /**
   * A Command is a function with an extra <code>canExecute</code> observable property to determine
   * whether the command can be executed.  When executed, a Command function will check the
   * value of <code>canExecute</code> and throw if false.
   *
   * This type describes an interface and is not intended to be instantiated directly.
   * See {@link createCommand} to create a command from a function.
   *
   * @alias Command
   * @constructor
   */
  function Command() {
    /**
     * Gets whether this command can currently be executed.  This property is observable.
     * @type {Boolean}
     * @default undefined
     */
    this.canExecute = undefined;

    /**
     * Gets an event which is raised before the command executes, the event
     * is raised with an object containing two properties: a <code>cancel</code> property,
     * which if set to false by the listener will prevent the command from being executed, and
     * an <code>args</code> property, which is the array of arguments being passed to the command.
     * @type {Event}
     * @default undefined
     */
    this.beforeExecute = undefined;

    /**
     * Gets an event which is raised after the command executes, the event
     * is raised with the return value of the command as its only parameter.
     * @type {Event}
     * @default undefined
     */
    this.afterExecute = undefined;

    DeveloperError.throwInstantiationError();
  }

  /**
   * A static class with helper functions used by the CesiumInspector and Cesium3DTilesInspector
   * @private
   */
  var InspectorShared = {};

  /**
   * Creates a checkbox component
   * @param {String} labelText The text to display in the checkbox label
   * @param {String} checkedBinding The name of the variable used for checked binding
   * @param {String} [enableBinding] The name of the variable used for enable binding
   * @return {Element}
   */
  InspectorShared.createCheckbox = function (
    labelText,
    checkedBinding,
    enableBinding
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.string("labelText", labelText);
    Check.typeOf.string("checkedBinding", checkedBinding);
    //>>includeEnd('debug');
    var checkboxContainer = document.createElement("div");
    var checkboxLabel = document.createElement("label");
    var checkboxInput = document.createElement("input");
    checkboxInput.type = "checkbox";

    var binding = "checked: " + checkedBinding;
    if (defined(enableBinding)) {
      binding += ", enable: " + enableBinding;
    }
    checkboxInput.setAttribute("data-bind", binding);
    checkboxLabel.appendChild(checkboxInput);
    checkboxLabel.appendChild(document.createTextNode(labelText));
    checkboxContainer.appendChild(checkboxLabel);
    return checkboxContainer;
  };

  /**
   * Creates a section element
   * @param {Element} panel The parent element
   * @param {String} headerText The text to display at the top of the section
   * @param {String} sectionVisibleBinding The name of the variable used for visible binding
   * @param {String} toggleSectionVisibilityBinding The name of the function used to toggle visibility
   * @return {Element}
   */
  InspectorShared.createSection = function (
    panel,
    headerText,
    sectionVisibleBinding,
    toggleSectionVisibilityBinding
  ) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("panel", panel);
    Check.typeOf.string("headerText", headerText);
    Check.typeOf.string("sectionVisibleBinding", sectionVisibleBinding);
    Check.typeOf.string(
      "toggleSectionVisibilityBinding",
      toggleSectionVisibilityBinding
    );
    //>>includeEnd('debug');
    var section = document.createElement("div");
    section.className = "cesium-cesiumInspector-section";
    section.setAttribute(
      "data-bind",
      'css: { "cesium-cesiumInspector-section-collapsed": !' +
        sectionVisibleBinding +
        " }"
    );
    panel.appendChild(section);

    var sectionHeader = document.createElement("h3");
    sectionHeader.className = "cesium-cesiumInspector-sectionHeader";
    sectionHeader.appendChild(document.createTextNode(headerText));
    sectionHeader.setAttribute(
      "data-bind",
      "click: " + toggleSectionVisibilityBinding
    );
    section.appendChild(sectionHeader);

    var sectionContent = document.createElement("div");
    sectionContent.className = "cesium-cesiumInspector-sectionContent";
    section.appendChild(sectionContent);
    return sectionContent;
  };

  /**
   * A view model which exposes the properties of a toggle button.
   * @alias ToggleButtonViewModel
   * @constructor
   *
   * @param {Command} command The command which will be executed when the button is toggled.
   * @param {Object} [options] Object with the following properties:
   * @param {Boolean} [options.toggled=false] A boolean indicating whether the button should be initially toggled.
   * @param {String} [options.tooltip=''] A string containing the button's tooltip.
   */
  function ToggleButtonViewModel(command, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(command)) {
      throw new DeveloperError("command is required.");
    }
    //>>includeEnd('debug');

    this._command = command;

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    /**
     * Gets or sets whether the button is currently toggled.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.toggled = defaultValue(options.toggled, false);

    /**
     * Gets or sets the button's tooltip.  This property is observable.
     * @type {String}
     * @default ''
     */
    this.tooltip = defaultValue(options.tooltip, "");

    knockout.track(this, ["toggled", "tooltip"]);
  }

  Object.defineProperties(ToggleButtonViewModel.prototype, {
    /**
     * Gets the command which will be executed when the button is toggled.
     * @memberof ToggleButtonViewModel.prototype
     * @type {Command}
     */
    command: {
      get: function () {
        return this._command;
      },
    },
  });

  /**
   * Create a Command from a given function, for use with ViewModels.
   *
   * A Command is a function with an extra <code>canExecute</code> observable property to determine
   * whether the command can be executed.  When executed, a Command function will check the
   * value of <code>canExecute</code> and throw if false.  It also provides events for when
   * a command has been or is about to be executed.
   *
   * @function
   *
   * @param {Function} func The function to execute.
   * @param {Boolean} [canExecute=true] A boolean indicating whether the function can currently be executed.
   */
  function createCommand$2(func, canExecute) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(func)) {
      throw new DeveloperError("func is required.");
    }
    //>>includeEnd('debug');

    canExecute = defaultValue(canExecute, true);

    var beforeExecute = new Event();
    var afterExecute = new Event();

    function command() {
      //>>includeStart('debug', pragmas.debug);
      if (!command.canExecute) {
        throw new DeveloperError("Cannot execute command, canExecute is false.");
      }
      //>>includeEnd('debug');

      var commandInfo = {
        args: arguments,
        cancel: false,
      };

      var result;
      beforeExecute.raiseEvent(commandInfo);
      if (!commandInfo.cancel) {
        result = func.apply(null, arguments);
        afterExecute.raiseEvent(result);
      }
      return result;
    }

    command.canExecute = canExecute;
    knockout.track(command, ["canExecute"]);

    Object.defineProperties(command, {
      beforeExecute: {
        value: beforeExecute,
      },
      afterExecute: {
        value: afterExecute,
      },
    });

    return command;
  }

  /**
   * Subscribe to a Knockout observable ES5 property, and immediately fire
   * the callback with the current value of the property.
   *
   * @private
   *
   * @function subscribeAndEvaluate
   *
   * @param {Object} owner The object containing the observable property.
   * @param {String} observablePropertyName The name of the observable property.
   * @param {Function} callback The callback function.
   * @param {Object} [target] The value of this in the callback function.
   * @param {String} [event='change'] The name of the event to receive notification for.
   * @returns The subscription object from Knockout which can be used to dispose the subscription later.
   */
  function subscribeAndEvaluate(
    owner,
    observablePropertyName,
    callback,
    target,
    event
  ) {
    callback.call(target, owner[observablePropertyName]);
    return knockout
      .getObservable(owner, observablePropertyName)
      .subscribe(callback, target, event);
  }

  //This file is automatically rebuilt by the Cesium build process.
  var DepthViewPacked = "uniform sampler2D u_depthTexture;\n\
varying vec2 v_textureCoordinates;\n\
void main()\n\
{\n\
float z_window = czm_unpackDepth(texture2D(u_depthTexture, v_textureCoordinates));\n\
z_window = czm_reverseLogDepth(z_window);\n\
float n_range = czm_depthRange.near;\n\
float f_range = czm_depthRange.far;\n\
float z_ndc = (2.0 * z_window - n_range - f_range) / (f_range - n_range);\n\
float scale = pow(z_ndc * 0.5 + 0.5, 8.0);\n\
gl_FragColor = vec4(mix(vec3(0.0), vec3(1.0), scale), 1.0);\n\
}\n\
";

  /**
       * Iterate through the objects within the glTF and delete their pipeline extras object.
       *
       * @param {Object} gltf A javascript object containing a glTF asset.
       * @returns {Object} glTF with no pipeline extras.
       *
       * @private
       */
      function removePipelineExtras(gltf) {
          ForEach.shader(gltf, function(shader) {
              removeExtras(shader);
          });
          ForEach.buffer(gltf, function(buffer) {
              removeExtras(buffer);
          });
          ForEach.image(gltf, function (image) {
              removeExtras(image);
              ForEach.compressedImage(image, function(compressedImage) {
                  removeExtras(compressedImage);
              });
          });

          removeExtras(gltf);

          return gltf;
      }

      function removeExtras(object) {
          if (!defined(object.extras)) {
              return;
          }

          if (defined(object.extras._pipeline)) {
              delete object.extras._pipeline;
          }

          if (Object.keys(object.extras).length === 0) {
              delete object.extras;
          }
      }

  var svgNS$1 = "http://www.w3.org/2000/svg";
  var xlinkNS = "http://www.w3.org/1999/xlink";

  var widgetForDrag;

  var gradientEnabledColor0 = Color.fromCssColorString("rgba(247,250,255,0.384)");
  var gradientEnabledColor1 = Color.fromCssColorString("rgba(143,191,255,0.216)");
  var gradientEnabledColor2 = Color.fromCssColorString("rgba(153,197,255,0.098)");
  var gradientEnabledColor3 = Color.fromCssColorString("rgba(255,255,255,0.086)");

  var gradientDisabledColor0 = Color.fromCssColorString(
    "rgba(255,255,255,0.267)"
  );
  var gradientDisabledColor1 = Color.fromCssColorString("rgba(255,255,255,0)");

  var gradientKnobColor = Color.fromCssColorString("rgba(66,67,68,0.3)");
  var gradientPointerColor = Color.fromCssColorString("rgba(0,0,0,0.5)");

  function getElementColor(element) {
    return Color.fromCssColorString(
      window.getComputedStyle(element).getPropertyValue("color")
    );
  }

  var svgIconsById = {
    animation_pathReset: {
      tagName: "path",
      transform: "translate(16,16) scale(0.85) translate(-16,-16)",
      d:
        "M24.316,5.318,9.833,13.682,9.833,5.5,5.5,5.5,5.5,25.5,9.833,25.5,9.833,17.318,24.316,25.682z",
    },
    animation_pathPause: {
      tagName: "path",
      transform: "translate(16,16) scale(0.85) translate(-16,-16)",
      d: "M13,5.5,7.5,5.5,7.5,25.5,13,25.5zM24.5,5.5,19,5.5,19,25.5,24.5,25.5z",
    },
    animation_pathPlay: {
      tagName: "path",
      transform: "translate(16,16) scale(0.85) translate(-16,-16)",
      d: "M6.684,25.682L24.316,15.5L6.684,5.318V25.682z",
    },
    animation_pathPlayReverse: {
      tagName: "path",
      transform: "translate(16,16) scale(-0.85,0.85) translate(-16,-16)",
      d: "M6.684,25.682L24.316,15.5L6.684,5.318V25.682z",
    },
    animation_pathLoop: {
      tagName: "path",
      transform: "translate(16,16) scale(0.85) translate(-16,-16)",
      d:
        "M24.249,15.499c-0.009,4.832-3.918,8.741-8.75,8.75c-2.515,0-4.768-1.064-6.365-2.763l2.068-1.442l-7.901-3.703l0.744,8.694l2.193-1.529c2.244,2.594,5.562,4.242,9.26,4.242c6.767,0,12.249-5.482,12.249-12.249H24.249zM15.499,6.75c2.516,0,4.769,1.065,6.367,2.764l-2.068,1.443l7.901,3.701l-0.746-8.693l-2.192,1.529c-2.245-2.594-5.562-4.245-9.262-4.245C8.734,3.25,3.25,8.734,3.249,15.499H6.75C6.758,10.668,10.668,6.758,15.499,6.75z",
    },
    animation_pathClock: {
      tagName: "path",
      transform: "translate(16,16) scale(0.85) translate(-16,-15.5)",
      d:
        "M15.5,2.374C8.251,2.375,2.376,8.251,2.374,15.5C2.376,22.748,8.251,28.623,15.5,28.627c7.249-0.004,13.124-5.879,13.125-13.127C28.624,8.251,22.749,2.375,15.5,2.374zM15.5,25.623C9.909,25.615,5.385,21.09,5.375,15.5C5.385,9.909,9.909,5.384,15.5,5.374c5.59,0.01,10.115,4.535,10.124,10.125C25.615,21.09,21.091,25.615,15.5,25.623zM8.625,15.5c-0.001-0.552-0.448-0.999-1.001-1c-0.553,0-1,0.448-1,1c0,0.553,0.449,1,1,1C8.176,16.5,8.624,16.053,8.625,15.5zM8.179,18.572c-0.478,0.277-0.642,0.889-0.365,1.367c0.275,0.479,0.889,0.641,1.365,0.365c0.479-0.275,0.643-0.887,0.367-1.367C9.27,18.461,8.658,18.297,8.179,18.572zM9.18,10.696c-0.479-0.276-1.09-0.112-1.366,0.366s-0.111,1.09,0.365,1.366c0.479,0.276,1.09,0.113,1.367-0.366C9.821,11.584,9.657,10.973,9.18,10.696zM22.822,12.428c0.478-0.275,0.643-0.888,0.366-1.366c-0.275-0.478-0.89-0.642-1.366-0.366c-0.479,0.278-0.642,0.89-0.366,1.367C21.732,12.54,22.344,12.705,22.822,12.428zM12.062,21.455c-0.478-0.275-1.089-0.111-1.366,0.367c-0.275,0.479-0.111,1.09,0.366,1.365c0.478,0.277,1.091,0.111,1.365-0.365C12.704,22.344,12.54,21.732,12.062,21.455zM12.062,9.545c0.479-0.276,0.642-0.888,0.366-1.366c-0.276-0.478-0.888-0.642-1.366-0.366s-0.642,0.888-0.366,1.366C10.973,9.658,11.584,9.822,12.062,9.545zM22.823,18.572c-0.48-0.275-1.092-0.111-1.367,0.365c-0.275,0.479-0.112,1.092,0.367,1.367c0.477,0.275,1.089,0.113,1.365-0.365C23.464,19.461,23.3,18.848,22.823,18.572zM19.938,7.813c-0.477-0.276-1.091-0.111-1.365,0.366c-0.275,0.48-0.111,1.091,0.366,1.367s1.089,0.112,1.366-0.366C20.581,8.702,20.418,8.089,19.938,7.813zM23.378,14.5c-0.554,0.002-1.001,0.45-1.001,1c0.001,0.552,0.448,1,1.001,1c0.551,0,1-0.447,1-1C24.378,14.949,23.929,14.5,23.378,14.5zM15.501,6.624c-0.552,0-1,0.448-1,1l-0.466,7.343l-3.004,1.96c-0.478,0.277-0.642,0.889-0.365,1.365c0.275,0.479,0.889,0.643,1.365,0.367l3.305-1.676C15.39,16.99,15.444,17,15.501,17c0.828,0,1.5-0.671,1.5-1.5l-0.5-7.876C16.501,7.072,16.053,6.624,15.501,6.624zM15.501,22.377c-0.552,0-1,0.447-1,1s0.448,1,1,1s1-0.447,1-1S16.053,22.377,15.501,22.377zM18.939,21.455c-0.479,0.277-0.643,0.889-0.366,1.367c0.275,0.477,0.888,0.643,1.366,0.365c0.478-0.275,0.642-0.889,0.366-1.365C20.028,21.344,19.417,21.18,18.939,21.455z",
    },
    animation_pathWingButton: {
      tagName: "path",
      d:
        "m 4.5,0.5 c -2.216,0 -4,1.784 -4,4 l 0,24 c 0,2.216 1.784,4 4,4 l 13.71875,0 C 22.478584,27.272785 27.273681,22.511272 32.5,18.25 l 0,-13.75 c 0,-2.216 -1.784,-4 -4,-4 l -24,0 z",
    },
    animation_pathPointer: {
      tagName: "path",
      d: "M-15,-65,-15,-55,15,-55,15,-65,0,-95z",
    },
    animation_pathSwooshFX: {
      tagName: "path",
      d:
        "m 85,0 c 0,16.617 -4.813944,35.356 -13.131081,48.4508 h 6.099803 c 8.317138,-13.0948 13.13322,-28.5955 13.13322,-45.2124 0,-46.94483 -38.402714,-85.00262 -85.7743869,-85.00262 -1.0218522,0 -2.0373001,0.0241 -3.0506131,0.0589 45.958443,1.59437 82.723058,35.77285 82.723058,81.70532 z",
    },
  };

  //Dynamically builds an SVG element from a JSON object.
  function svgFromObject(obj) {
    var ele = document.createElementNS(svgNS$1, obj.tagName);
    for (var field in obj) {
      if (obj.hasOwnProperty(field) && field !== "tagName") {
        if (field === "children") {
          var i;
          var len = obj.children.length;
          for (i = 0; i < len; ++i) {
            ele.appendChild(svgFromObject(obj.children[i]));
          }
        } else if (field.indexOf("xlink:") === 0) {
          ele.setAttributeNS(xlinkNS, field.substring(6), obj[field]);
        } else if (field === "textContent") {
          ele.textContent = obj[field];
        } else {
          ele.setAttribute(field, obj[field]);
        }
      }
    }
    return ele;
  }

  function svgText(x, y, msg) {
    var text = document.createElementNS(svgNS$1, "text");
    text.setAttribute("x", x);
    text.setAttribute("y", y);
    text.setAttribute("class", "cesium-animation-svgText");

    var tspan = document.createElementNS(svgNS$1, "tspan");
    tspan.textContent = msg;
    text.appendChild(tspan);
    return text;
  }

  function setShuttleRingPointer(shuttleRingPointer, knobOuter, angle) {
    shuttleRingPointer.setAttribute(
      "transform",
      "translate(100,100) rotate(" + angle + ")"
    );
    knobOuter.setAttribute("transform", "rotate(" + angle + ")");
  }

  var makeColorStringScratch = new Color();
  function makeColorString(background, gradient) {
    var gradientAlpha = gradient.alpha;
    var backgroundAlpha = 1.0 - gradientAlpha;
    makeColorStringScratch.red =
      background.red * backgroundAlpha + gradient.red * gradientAlpha;
    makeColorStringScratch.green =
      background.green * backgroundAlpha + gradient.green * gradientAlpha;
    makeColorStringScratch.blue =
      background.blue * backgroundAlpha + gradient.blue * gradientAlpha;
    return makeColorStringScratch.toCssColorString();
  }

  function rectButton(x, y, path) {
    var iconInfo = svgIconsById[path];

    var button = {
      tagName: "g",
      class: "cesium-animation-rectButton",
      transform: "translate(" + x + "," + y + ")",
      children: [
        {
          tagName: "rect",
          class: "cesium-animation-buttonGlow",
          width: 32,
          height: 32,
          rx: 2,
          ry: 2,
        },
        {
          tagName: "rect",
          class: "cesium-animation-buttonMain",
          width: 32,
          height: 32,
          rx: 4,
          ry: 4,
        },
        {
          class: "cesium-animation-buttonPath",
          id: path,
          tagName: iconInfo.tagName,
          transform: iconInfo.transform,
          d: iconInfo.d,
        },
        {
          tagName: "title",
          textContent: "",
        },
      ],
    };
    return svgFromObject(button);
  }

  function wingButton(x, y, path) {
    var buttonIconInfo = svgIconsById[path];
    var wingIconInfo = svgIconsById["animation_pathWingButton"];

    var button = {
      tagName: "g",
      class: "cesium-animation-rectButton",
      transform: "translate(" + x + "," + y + ")",
      children: [
        {
          class: "cesium-animation-buttonGlow",
          id: "animation_pathWingButton",
          tagName: wingIconInfo.tagName,
          d: wingIconInfo.d,
        },
        {
          class: "cesium-animation-buttonMain",
          id: "animation_pathWingButton",
          tagName: wingIconInfo.tagName,
          d: wingIconInfo.d,
        },
        {
          class: "cesium-animation-buttonPath",
          id: path,
          tagName: buttonIconInfo.tagName,
          transform: buttonIconInfo.transform,
          d: buttonIconInfo.d,
        },
        {
          tagName: "title",
          textContent: "",
        },
      ],
    };
    return svgFromObject(button);
  }

  function setShuttleRingFromMouseOrTouch(widget, e) {
    var viewModel = widget._viewModel;
    var shuttleRingDragging = viewModel.shuttleRingDragging;

    if (shuttleRingDragging && widgetForDrag !== widget) {
      return;
    }

    if (
      e.type === "mousedown" ||
      (shuttleRingDragging && e.type === "mousemove") ||
      (e.type === "touchstart" && e.touches.length === 1) ||
      (shuttleRingDragging && e.type === "touchmove" && e.touches.length === 1)
    ) {
      var centerX = widget._centerX;
      var centerY = widget._centerY;
      var svg = widget._svgNode;
      var rect = svg.getBoundingClientRect();
      var clientX;
      var clientY;
      if (e.type === "touchstart" || e.type === "touchmove") {
        clientX = e.touches[0].clientX;
        clientY = e.touches[0].clientY;
      } else {
        clientX = e.clientX;
        clientY = e.clientY;
      }

      if (
        !shuttleRingDragging &&
        (clientX > rect.right ||
          clientX < rect.left ||
          clientY < rect.top ||
          clientY > rect.bottom)
      ) {
        return;
      }

      var pointerRect = widget._shuttleRingPointer.getBoundingClientRect();

      var x = clientX - centerX - rect.left;
      var y = clientY - centerY - rect.top;

      var angle = (Math.atan2(y, x) * 180) / Math.PI + 90;
      if (angle > 180) {
        angle -= 360;
      }
      var shuttleRingAngle = viewModel.shuttleRingAngle;
      if (
        shuttleRingDragging ||
        (clientX < pointerRect.right &&
          clientX > pointerRect.left &&
          clientY > pointerRect.top &&
          clientY < pointerRect.bottom)
      ) {
        widgetForDrag = widget;
        viewModel.shuttleRingDragging = true;
        viewModel.shuttleRingAngle = angle;
      } else if (angle < shuttleRingAngle) {
        viewModel.slower();
      } else if (angle > shuttleRingAngle) {
        viewModel.faster();
      }
      e.preventDefault();
    } else {
      if (widget === widgetForDrag) {
        widgetForDrag = undefined;
      }
      viewModel.shuttleRingDragging = false;
    }
  }

  //This is a private class for treating an SVG element like a button.
  //If we ever need a general purpose SVG button, we can make this generic.
  function SvgButton(svgElement, viewModel) {
    this._viewModel = viewModel;
    this.svgElement = svgElement;
    this._enabled = undefined;
    this._toggled = undefined;

    var that = this;
    this._clickFunction = function () {
      var command = that._viewModel.command;
      if (command.canExecute) {
        command();
      }
    };

    svgElement.addEventListener("click", this._clickFunction, true);

    //TODO: Since the animation widget uses SVG and has no HTML backing,
    //we need to wire everything up manually.  Knockout can supposedly
    //bind to SVG, so we we figure that out we can modify our SVG
    //to include the binding information directly.

    this._subscriptions = [
      //
      subscribeAndEvaluate(viewModel, "toggled", this.setToggled, this), //
      subscribeAndEvaluate(viewModel, "tooltip", this.setTooltip, this), //
      subscribeAndEvaluate(
        viewModel.command,
        "canExecute",
        this.setEnabled,
        this
      ),
    ];
  }

  SvgButton.prototype.destroy = function () {
    this.svgElement.removeEventListener("click", this._clickFunction, true);
    var subscriptions = this._subscriptions;
    for (var i = 0, len = subscriptions.length; i < len; i++) {
      subscriptions[i].dispose();
    }
    destroyObject(this);
  };

  SvgButton.prototype.isDestroyed = function () {
    return false;
  };

  SvgButton.prototype.setEnabled = function (enabled) {
    if (this._enabled !== enabled) {
      this._enabled = enabled;

      if (!enabled) {
        this.svgElement.setAttribute("class", "cesium-animation-buttonDisabled");
        return;
      }

      if (this._toggled) {
        this.svgElement.setAttribute(
          "class",
          "cesium-animation-rectButton cesium-animation-buttonToggled"
        );
        return;
      }

      this.svgElement.setAttribute("class", "cesium-animation-rectButton");
    }
  };

  SvgButton.prototype.setToggled = function (toggled) {
    if (this._toggled !== toggled) {
      this._toggled = toggled;

      if (this._enabled) {
        if (toggled) {
          this.svgElement.setAttribute(
            "class",
            "cesium-animation-rectButton cesium-animation-buttonToggled"
          );
        } else {
          this.svgElement.setAttribute("class", "cesium-animation-rectButton");
        }
      }
    }
  };

  SvgButton.prototype.setTooltip = function (tooltip) {
    this.svgElement.getElementsByTagName("title")[0].textContent = tooltip;
  };

  /**
   * <span style="display: block; text-align: center;">
   * <img src="Images/AnimationWidget.png" width="211" height="142" alt="" />
   * <br />Animation widget
   * </span>
   * <br /><br />
   * The Animation widget provides buttons for play, pause, and reverse, along with the
   * current time and date, surrounded by a "shuttle ring" for controlling the speed of animation.
   * <br /><br />
   * The "shuttle ring" concept is borrowed from video editing, where typically a
   * "jog wheel" can be rotated to move past individual animation frames very slowly, and
   * a surrounding shuttle ring can be twisted to control direction and speed of fast playback.
   * Cesium typically treats time as continuous (not broken into pre-defined animation frames),
   * so this widget offers no jog wheel.  Instead, the shuttle ring is capable of both fast and
   * very slow playback.  Click and drag the shuttle ring pointer itself (shown above in green),
   * or click in the rest of the ring area to nudge the pointer to the next preset speed in that direction.
   * <br /><br />
   * The Animation widget also provides a "realtime" button (in the upper-left) that keeps
   * animation time in sync with the end user's system clock, typically displaying
   * "today" or "right now."  This mode is not available in {@link ClockRange.CLAMPED} or
   * {@link ClockRange.LOOP_STOP} mode if the current time is outside of {@link Clock}'s startTime and endTime.
   *
   * @alias Animation
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {AnimationViewModel} viewModel The view model used by this widget.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   *
   * @example
   * // In HTML head, include a link to Animation.css stylesheet,
   * // and in the body, include: <div id="animationContainer"></div>
   *
   * var clock = new Cesium.Clock();
   * var clockViewModel = new Cesium.ClockViewModel(clock);
   * var viewModel = new Cesium.AnimationViewModel(clockViewModel);
   * var widget = new Cesium.Animation('animationContainer', viewModel);
   *
   * function tick() {
   *     clock.tick();
   *     Cesium.requestAnimationFrame(tick);
   * }
   * Cesium.requestAnimationFrame(tick);
   *
   * @see AnimationViewModel
   * @see Clock
   */
  function Animation(container, viewModel) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    if (!defined(viewModel)) {
      throw new DeveloperError("viewModel is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);
    this._viewModel = viewModel;
    this._container = container;
    this._centerX = 0;
    this._centerY = 0;
    this._defsElement = undefined;
    this._svgNode = undefined;
    this._topG = undefined;
    this._lastHeight = undefined;
    this._lastWidth = undefined;

    var ownerDocument = container.ownerDocument;

    // Firefox requires SVG references to be included directly, not imported from external CSS.
    // Also, CSS minifiers get confused by this being in an external CSS file.
    var cssStyle = document.createElement("style");
    cssStyle.textContent =
      ".cesium-animation-rectButton .cesium-animation-buttonGlow { filter: url(#animation_blurred); }\
.cesium-animation-rectButton .cesium-animation-buttonMain { fill: url(#animation_buttonNormal); }\
.cesium-animation-buttonToggled .cesium-animation-buttonMain { fill: url(#animation_buttonToggled); }\
.cesium-animation-rectButton:hover .cesium-animation-buttonMain { fill: url(#animation_buttonHovered); }\
.cesium-animation-buttonDisabled .cesium-animation-buttonMain { fill: url(#animation_buttonDisabled); }\
.cesium-animation-shuttleRingG .cesium-animation-shuttleRingSwoosh { fill: url(#animation_shuttleRingSwooshGradient); }\
.cesium-animation-shuttleRingG:hover .cesium-animation-shuttleRingSwoosh { fill: url(#animation_shuttleRingSwooshHovered); }\
.cesium-animation-shuttleRingPointer { fill: url(#animation_shuttleRingPointerGradient); }\
.cesium-animation-shuttleRingPausePointer { fill: url(#animation_shuttleRingPointerPaused); }\
.cesium-animation-knobOuter { fill: url(#animation_knobOuter); }\
.cesium-animation-knobInner { fill: url(#animation_knobInner); }";

    ownerDocument.head.insertBefore(cssStyle, ownerDocument.head.childNodes[0]);

    var themeEle = document.createElement("div");
    themeEle.className = "cesium-animation-theme";
    themeEle.innerHTML =
      '<div class="cesium-animation-themeNormal"></div>\
<div class="cesium-animation-themeHover"></div>\
<div class="cesium-animation-themeSelect"></div>\
<div class="cesium-animation-themeDisabled"></div>\
<div class="cesium-animation-themeKnob"></div>\
<div class="cesium-animation-themePointer"></div>\
<div class="cesium-animation-themeSwoosh"></div>\
<div class="cesium-animation-themeSwooshHover"></div>';

    this._theme = themeEle;
    this._themeNormal = themeEle.childNodes[0];
    this._themeHover = themeEle.childNodes[1];
    this._themeSelect = themeEle.childNodes[2];
    this._themeDisabled = themeEle.childNodes[3];
    this._themeKnob = themeEle.childNodes[4];
    this._themePointer = themeEle.childNodes[5];
    this._themeSwoosh = themeEle.childNodes[6];
    this._themeSwooshHover = themeEle.childNodes[7];

    var svg = document.createElementNS(svgNS$1, "svg:svg");
    this._svgNode = svg;

    // Define the XLink namespace that SVG uses
    svg.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:xlink", xlinkNS);

    var topG = document.createElementNS(svgNS$1, "g");
    this._topG = topG;

    this._realtimeSVG = new SvgButton(
      wingButton(3, 4, "animation_pathClock"),
      viewModel.playRealtimeViewModel
    );
    this._playReverseSVG = new SvgButton(
      rectButton(44, 99, "animation_pathPlayReverse"),
      viewModel.playReverseViewModel
    );
    this._playForwardSVG = new SvgButton(
      rectButton(124, 99, "animation_pathPlay"),
      viewModel.playForwardViewModel
    );
    this._pauseSVG = new SvgButton(
      rectButton(84, 99, "animation_pathPause"),
      viewModel.pauseViewModel
    );

    var buttonsG = document.createElementNS(svgNS$1, "g");
    buttonsG.appendChild(this._realtimeSVG.svgElement);
    buttonsG.appendChild(this._playReverseSVG.svgElement);
    buttonsG.appendChild(this._playForwardSVG.svgElement);
    buttonsG.appendChild(this._pauseSVG.svgElement);

    var shuttleRingBackPanel = svgFromObject({
      tagName: "circle",
      class: "cesium-animation-shuttleRingBack",
      cx: 100,
      cy: 100,
      r: 99,
    });
    this._shuttleRingBackPanel = shuttleRingBackPanel;

    var swooshIconInfo = svgIconsById["animation_pathSwooshFX"];
    var shuttleRingPointerIconInfo = svgIconsById["animation_pathPointer"];

    var shuttleRingSwooshG = svgFromObject({
      tagName: "g",
      class: "cesium-animation-shuttleRingSwoosh",
      children: [
        {
          tagName: swooshIconInfo.tagName,
          transform: "translate(100,97) scale(-1,1)",
          id: "animation_pathSwooshFX",
          d: swooshIconInfo.d,
        },
        {
          tagName: swooshIconInfo.tagName,
          transform: "translate(100,97)",
          id: "animation_pathSwooshFX",
          d: swooshIconInfo.d,
        },
        {
          tagName: "line",
          x1: 100,
          y1: 8,
          x2: 100,
          y2: 22,
        },
      ],
    });
    this._shuttleRingSwooshG = shuttleRingSwooshG;

    this._shuttleRingPointer = svgFromObject({
      class: "cesium-animation-shuttleRingPointer",
      id: "animation_pathPointer",
      tagName: shuttleRingPointerIconInfo.tagName,
      d: shuttleRingPointerIconInfo.d,
    });

    var knobG = svgFromObject({
      tagName: "g",
      transform: "translate(100,100)",
    });

    this._knobOuter = svgFromObject({
      tagName: "circle",
      class: "cesium-animation-knobOuter",
      cx: 0,
      cy: 0,
      r: 71,
    });

    var knobInnerAndShieldSize = 61;

    var knobInner = svgFromObject({
      tagName: "circle",
      class: "cesium-animation-knobInner",
      cx: 0,
      cy: 0,
      r: knobInnerAndShieldSize,
    });

    this._knobDate = svgText(0, -24, "");
    this._knobTime = svgText(0, -7, "");
    this._knobStatus = svgText(0, -41, "");

    // widget shield catches clicks on the knob itself (even while DOM elements underneath are changing).
    var knobShield = svgFromObject({
      tagName: "circle",
      class: "cesium-animation-blank",
      cx: 0,
      cy: 0,
      r: knobInnerAndShieldSize,
    });

    var shuttleRingBackG = document.createElementNS(svgNS$1, "g");
    shuttleRingBackG.setAttribute("class", "cesium-animation-shuttleRingG");

    container.appendChild(themeEle);
    topG.appendChild(shuttleRingBackG);
    topG.appendChild(knobG);
    topG.appendChild(buttonsG);

    shuttleRingBackG.appendChild(shuttleRingBackPanel);
    shuttleRingBackG.appendChild(shuttleRingSwooshG);
    shuttleRingBackG.appendChild(this._shuttleRingPointer);

    knobG.appendChild(this._knobOuter);
    knobG.appendChild(knobInner);
    knobG.appendChild(this._knobDate);
    knobG.appendChild(this._knobTime);
    knobG.appendChild(this._knobStatus);
    knobG.appendChild(knobShield);

    svg.appendChild(topG);
    container.appendChild(svg);

    var that = this;
    function mouseCallback(e) {
      setShuttleRingFromMouseOrTouch(that, e);
    }
    this._mouseCallback = mouseCallback;

    shuttleRingBackPanel.addEventListener("mousedown", mouseCallback, true);
    shuttleRingBackPanel.addEventListener("touchstart", mouseCallback, true);
    shuttleRingSwooshG.addEventListener("mousedown", mouseCallback, true);
    shuttleRingSwooshG.addEventListener("touchstart", mouseCallback, true);
    ownerDocument.addEventListener("mousemove", mouseCallback, true);
    ownerDocument.addEventListener("touchmove", mouseCallback, true);
    ownerDocument.addEventListener("mouseup", mouseCallback, true);
    ownerDocument.addEventListener("touchend", mouseCallback, true);
    ownerDocument.addEventListener("touchcancel", mouseCallback, true);
    this._shuttleRingPointer.addEventListener("mousedown", mouseCallback, true);
    this._shuttleRingPointer.addEventListener("touchstart", mouseCallback, true);
    this._knobOuter.addEventListener("mousedown", mouseCallback, true);
    this._knobOuter.addEventListener("touchstart", mouseCallback, true);

    //TODO: Since the animation widget uses SVG and has no HTML backing,
    //we need to wire everything up manually.  Knockout can supposedly
    //bind to SVG, so we we figure that out we can modify our SVG
    //to include the binding information directly.

    var timeNode = this._knobTime.childNodes[0];
    var dateNode = this._knobDate.childNodes[0];
    var statusNode = this._knobStatus.childNodes[0];
    var isPaused;
    this._subscriptions = [
      //
      subscribeAndEvaluate(viewModel.pauseViewModel, "toggled", function (value) {
        if (isPaused !== value) {
          isPaused = value;
          if (isPaused) {
            that._shuttleRingPointer.setAttribute(
              "class",
              "cesium-animation-shuttleRingPausePointer"
            );
          } else {
            that._shuttleRingPointer.setAttribute(
              "class",
              "cesium-animation-shuttleRingPointer"
            );
          }
        }
      }),

      subscribeAndEvaluate(viewModel, "shuttleRingAngle", function (value) {
        setShuttleRingPointer(that._shuttleRingPointer, that._knobOuter, value);
      }),

      subscribeAndEvaluate(viewModel, "dateLabel", function (value) {
        if (dateNode.textContent !== value) {
          dateNode.textContent = value;
        }
      }),

      subscribeAndEvaluate(viewModel, "timeLabel", function (value) {
        if (timeNode.textContent !== value) {
          timeNode.textContent = value;
        }
      }),

      subscribeAndEvaluate(viewModel, "multiplierLabel", function (value) {
        if (statusNode.textContent !== value) {
          statusNode.textContent = value;
        }
      }),
    ];

    this.applyThemeChanges();
    this.resize();
  }

  Object.defineProperties(Animation.prototype, {
    /**
     * Gets the parent container.
     *
     * @memberof Animation.prototype
     * @type {Element}
     * @readonly
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     *
     * @memberof Animation.prototype
     * @type {AnimationViewModel}
     * @readonly
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  Animation.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the animation widget.  Should be called if permanently
   * removing the widget from layout.
   */
  Animation.prototype.destroy = function () {
    if (defined(this._observer)) {
      this._observer.disconnect();
      this._observer = undefined;
    }

    var doc = this._container.ownerDocument;

    var mouseCallback = this._mouseCallback;
    this._shuttleRingBackPanel.removeEventListener(
      "mousedown",
      mouseCallback,
      true
    );
    this._shuttleRingBackPanel.removeEventListener(
      "touchstart",
      mouseCallback,
      true
    );
    this._shuttleRingSwooshG.removeEventListener(
      "mousedown",
      mouseCallback,
      true
    );
    this._shuttleRingSwooshG.removeEventListener(
      "touchstart",
      mouseCallback,
      true
    );
    doc.removeEventListener("mousemove", mouseCallback, true);
    doc.removeEventListener("touchmove", mouseCallback, true);
    doc.removeEventListener("mouseup", mouseCallback, true);
    doc.removeEventListener("touchend", mouseCallback, true);
    doc.removeEventListener("touchcancel", mouseCallback, true);
    this._shuttleRingPointer.removeEventListener(
      "mousedown",
      mouseCallback,
      true
    );
    this._shuttleRingPointer.removeEventListener(
      "touchstart",
      mouseCallback,
      true
    );
    this._knobOuter.removeEventListener("mousedown", mouseCallback, true);
    this._knobOuter.removeEventListener("touchstart", mouseCallback, true);

    this._container.removeChild(this._svgNode);
    this._container.removeChild(this._theme);
    this._realtimeSVG.destroy();
    this._playReverseSVG.destroy();
    this._playForwardSVG.destroy();
    this._pauseSVG.destroy();

    var subscriptions = this._subscriptions;
    for (var i = 0, len = subscriptions.length; i < len; i++) {
      subscriptions[i].dispose();
    }

    return destroyObject(this);
  };

  /**
   * Resizes the widget to match the container size.
   * This function should be called whenever the container size is changed.
   */
  Animation.prototype.resize = function () {
    var parentWidth = this._container.clientWidth;
    var parentHeight = this._container.clientHeight;
    if (parentWidth === this._lastWidth && parentHeight === this._lastHeight) {
      return;
    }

    var svg = this._svgNode;

    //The width and height as the SVG was originally drawn.
    var baseWidth = 200;
    var baseHeight = 132;

    var width = parentWidth;
    var height = parentHeight;

    if (parentWidth === 0 && parentHeight === 0) {
      width = baseWidth;
      height = baseHeight;
    } else if (parentWidth === 0) {
      height = parentHeight;
      width = baseWidth * (parentHeight / baseHeight);
    } else if (parentHeight === 0) {
      width = parentWidth;
      height = baseHeight * (parentWidth / baseWidth);
    }

    var scaleX = width / baseWidth;
    var scaleY = height / baseHeight;

    svg.style.cssText =
      "width: " +
      width +
      "px; height: " +
      height +
      "px; position: absolute; bottom: 0; left: 0; overflow: hidden;";
    svg.setAttribute("width", width);
    svg.setAttribute("height", height);
    svg.setAttribute("viewBox", "0 0 " + width + " " + height);

    this._topG.setAttribute("transform", "scale(" + scaleX + "," + scaleY + ")");

    this._centerX = Math.max(1, 100.0 * scaleX);
    this._centerY = Math.max(1, 100.0 * scaleY);

    this._lastHeight = parentWidth;
    this._lastWidth = parentHeight;
  };

  /**
   * Updates the widget to reflect any modified CSS rules for theming.
   *
   * @example
   * //Switch to the cesium-lighter theme.
   * document.body.className = 'cesium-lighter';
   * animation.applyThemeChanges();
   */
  Animation.prototype.applyThemeChanges = function () {
    // Since we rely on computed styles for themeing, we can't actually
    // do anything if the container has not yet been added to the DOM.
    // Set up an observer to be notified when it is added and apply
    // the changes at that time.

    var doc = this._container.ownerDocument;

    if (!doc.body.contains(this._container)) {
      if (defined(this._observer)) {
        //Already listening.
        return;
      }
      var that = this;
      that._observer = new MutationObserver(function () {
        if (doc.body.contains(that._container)) {
          that._observer.disconnect();
          that._observer = undefined;
          that.applyThemeChanges();
        }
      });
      that._observer.observe(doc, { childList: true, subtree: true });
      return;
    }

    var buttonNormalBackColor = getElementColor(this._themeNormal);
    var buttonHoverBackColor = getElementColor(this._themeHover);
    var buttonToggledBackColor = getElementColor(this._themeSelect);
    var buttonDisabledBackColor = getElementColor(this._themeDisabled);
    var knobBackColor = getElementColor(this._themeKnob);
    var pointerColor = getElementColor(this._themePointer);
    var swooshColor = getElementColor(this._themeSwoosh);
    var swooshHoverColor = getElementColor(this._themeSwooshHover);

    var defsElement = svgFromObject({
      tagName: "defs",
      children: [
        {
          id: "animation_buttonNormal",
          tagName: "linearGradient",
          x1: "50%",
          y1: "0%",
          x2: "50%",
          y2: "100%",
          children: [
            //add a 'stop-opacity' field to make translucent.
            {
              tagName: "stop",
              offset: "0%",
              "stop-color": makeColorString(
                buttonNormalBackColor,
                gradientEnabledColor0
              ),
            },
            {
              tagName: "stop",
              offset: "12%",
              "stop-color": makeColorString(
                buttonNormalBackColor,
                gradientEnabledColor1
              ),
            },
            {
              tagName: "stop",
              offset: "46%",
              "stop-color": makeColorString(
                buttonNormalBackColor,
                gradientEnabledColor2
              ),
            },
            {
              tagName: "stop",
              offset: "81%",
              "stop-color": makeColorString(
                buttonNormalBackColor,
                gradientEnabledColor3
              ),
            },
          ],
        },
        {
          id: "animation_buttonHovered",
          tagName: "linearGradient",
          x1: "50%",
          y1: "0%",
          x2: "50%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-color": makeColorString(
                buttonHoverBackColor,
                gradientEnabledColor0
              ),
            },
            {
              tagName: "stop",
              offset: "12%",
              "stop-color": makeColorString(
                buttonHoverBackColor,
                gradientEnabledColor1
              ),
            },
            {
              tagName: "stop",
              offset: "46%",
              "stop-color": makeColorString(
                buttonHoverBackColor,
                gradientEnabledColor2
              ),
            },
            {
              tagName: "stop",
              offset: "81%",
              "stop-color": makeColorString(
                buttonHoverBackColor,
                gradientEnabledColor3
              ),
            },
          ],
        },
        {
          id: "animation_buttonToggled",
          tagName: "linearGradient",
          x1: "50%",
          y1: "0%",
          x2: "50%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-color": makeColorString(
                buttonToggledBackColor,
                gradientEnabledColor0
              ),
            },
            {
              tagName: "stop",
              offset: "12%",
              "stop-color": makeColorString(
                buttonToggledBackColor,
                gradientEnabledColor1
              ),
            },
            {
              tagName: "stop",
              offset: "46%",
              "stop-color": makeColorString(
                buttonToggledBackColor,
                gradientEnabledColor2
              ),
            },
            {
              tagName: "stop",
              offset: "81%",
              "stop-color": makeColorString(
                buttonToggledBackColor,
                gradientEnabledColor3
              ),
            },
          ],
        },
        {
          id: "animation_buttonDisabled",
          tagName: "linearGradient",
          x1: "50%",
          y1: "0%",
          x2: "50%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-color": makeColorString(
                buttonDisabledBackColor,
                gradientDisabledColor0
              ),
            },
            {
              tagName: "stop",
              offset: "75%",
              "stop-color": makeColorString(
                buttonDisabledBackColor,
                gradientDisabledColor1
              ),
            },
          ],
        },
        {
          id: "animation_blurred",
          tagName: "filter",
          width: "200%",
          height: "200%",
          x: "-50%",
          y: "-50%",
          children: [
            {
              tagName: "feGaussianBlur",
              stdDeviation: 4,
              in: "SourceGraphic",
            },
          ],
        },
        {
          id: "animation_shuttleRingSwooshGradient",
          tagName: "linearGradient",
          x1: "50%",
          y1: "0%",
          x2: "50%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-opacity": 0.2,
              "stop-color": swooshColor.toCssColorString(),
            },
            {
              tagName: "stop",
              offset: "85%",
              "stop-opacity": 0.85,
              "stop-color": swooshColor.toCssColorString(),
            },
            {
              tagName: "stop",
              offset: "95%",
              "stop-opacity": 0.05,
              "stop-color": swooshColor.toCssColorString(),
            },
          ],
        },
        {
          id: "animation_shuttleRingSwooshHovered",
          tagName: "linearGradient",
          x1: "50%",
          y1: "0%",
          x2: "50%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-opacity": 0.2,
              "stop-color": swooshHoverColor.toCssColorString(),
            },
            {
              tagName: "stop",
              offset: "85%",
              "stop-opacity": 0.85,
              "stop-color": swooshHoverColor.toCssColorString(),
            },
            {
              tagName: "stop",
              offset: "95%",
              "stop-opacity": 0.05,
              "stop-color": swooshHoverColor.toCssColorString(),
            },
          ],
        },
        {
          id: "animation_shuttleRingPointerGradient",
          tagName: "linearGradient",
          x1: "0%",
          y1: "50%",
          x2: "100%",
          y2: "50%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-color": pointerColor.toCssColorString(),
            },
            {
              tagName: "stop",
              offset: "40%",
              "stop-color": pointerColor.toCssColorString(),
            },
            {
              tagName: "stop",
              offset: "60%",
              "stop-color": makeColorString(pointerColor, gradientPointerColor),
            },
            {
              tagName: "stop",
              offset: "100%",
              "stop-color": makeColorString(pointerColor, gradientPointerColor),
            },
          ],
        },
        {
          id: "animation_shuttleRingPointerPaused",
          tagName: "linearGradient",
          x1: "0%",
          y1: "50%",
          x2: "100%",
          y2: "50%",
          children: [
            {
              tagName: "stop",
              offset: "0%",
              "stop-color": "#CCC",
            },
            {
              tagName: "stop",
              offset: "40%",
              "stop-color": "#CCC",
            },
            {
              tagName: "stop",
              offset: "60%",
              "stop-color": "#555",
            },
            {
              tagName: "stop",
              offset: "100%",
              "stop-color": "#555",
            },
          ],
        },
        {
          id: "animation_knobOuter",
          tagName: "linearGradient",
          x1: "20%",
          y1: "0%",
          x2: "90%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "5%",
              "stop-color": makeColorString(knobBackColor, gradientEnabledColor0),
            },
            {
              tagName: "stop",
              offset: "60%",
              "stop-color": makeColorString(knobBackColor, gradientKnobColor),
            },
            {
              tagName: "stop",
              offset: "85%",
              "stop-color": makeColorString(knobBackColor, gradientEnabledColor1),
            },
          ],
        },
        {
          id: "animation_knobInner",
          tagName: "linearGradient",
          x1: "20%",
          y1: "0%",
          x2: "90%",
          y2: "100%",
          children: [
            {
              tagName: "stop",
              offset: "5%",
              "stop-color": makeColorString(knobBackColor, gradientKnobColor),
            },
            {
              tagName: "stop",
              offset: "60%",
              "stop-color": makeColorString(knobBackColor, gradientEnabledColor0),
            },
            {
              tagName: "stop",
              offset: "85%",
              "stop-color": makeColorString(knobBackColor, gradientEnabledColor3),
            },
          ],
        },
      ],
    });

    if (!defined(this._defsElement)) {
      this._svgNode.appendChild(defsElement);
    } else {
      this._svgNode.replaceChild(defsElement, this._defsElement);
    }
    this._defsElement = defsElement;
  };

  var monthNames = [
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug",
    "Sep",
    "Oct",
    "Nov",
    "Dec",
  ];
  var realtimeShuttleRingAngle = 15;
  var maxShuttleRingAngle = 105;

  function numberComparator(left, right) {
    return left - right;
  }

  function getTypicalMultiplierIndex(multiplier, shuttleRingTicks) {
    var index = binarySearch(shuttleRingTicks, multiplier, numberComparator);
    return index < 0 ? ~index : index;
  }

  function angleToMultiplier(angle, shuttleRingTicks) {
    //Use a linear scale for -1 to 1 between -15 < angle < 15 degrees
    if (Math.abs(angle) <= realtimeShuttleRingAngle) {
      return angle / realtimeShuttleRingAngle;
    }

    var minp = realtimeShuttleRingAngle;
    var maxp = maxShuttleRingAngle;
    var maxv;
    var minv = 0;
    var scale;
    if (angle > 0) {
      maxv = Math.log(shuttleRingTicks[shuttleRingTicks.length - 1]);
      scale = (maxv - minv) / (maxp - minp);
      return Math.exp(minv + scale * (angle - minp));
    }

    maxv = Math.log(-shuttleRingTicks[0]);
    scale = (maxv - minv) / (maxp - minp);
    return -Math.exp(minv + scale * (Math.abs(angle) - minp));
  }

  function multiplierToAngle(multiplier, shuttleRingTicks, clockViewModel) {
    if (clockViewModel.clockStep === ClockStep$1.SYSTEM_CLOCK) {
      return realtimeShuttleRingAngle;
    }

    if (Math.abs(multiplier) <= 1) {
      return multiplier * realtimeShuttleRingAngle;
    }

    var fastedMultipler = shuttleRingTicks[shuttleRingTicks.length - 1];
    if (multiplier > fastedMultipler) {
      multiplier = fastedMultipler;
    } else if (multiplier < -fastedMultipler) {
      multiplier = -fastedMultipler;
    }

    var minp = realtimeShuttleRingAngle;
    var maxp = maxShuttleRingAngle;
    var maxv;
    var minv = 0;
    var scale;

    if (multiplier > 0) {
      maxv = Math.log(fastedMultipler);
      scale = (maxv - minv) / (maxp - minp);
      return (Math.log(multiplier) - minv) / scale + minp;
    }

    maxv = Math.log(-shuttleRingTicks[0]);
    scale = (maxv - minv) / (maxp - minp);
    return -((Math.log(Math.abs(multiplier)) - minv) / scale + minp);
  }

  /**
   * The view model for the {@link Animation} widget.
   * @alias AnimationViewModel
   * @constructor
   *
   * @param {ClockViewModel} clockViewModel The ClockViewModel instance to use.
   *
   * @see Animation
   */
  function AnimationViewModel(clockViewModel) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(clockViewModel)) {
      throw new DeveloperError("clockViewModel is required.");
    }
    //>>includeEnd('debug');

    var that = this;
    this._clockViewModel = clockViewModel;
    this._allShuttleRingTicks = [];
    this._dateFormatter = AnimationViewModel.defaultDateFormatter;
    this._timeFormatter = AnimationViewModel.defaultTimeFormatter;

    /**
     * Gets or sets whether the shuttle ring is currently being dragged.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.shuttleRingDragging = false;

    /**
     * Gets or sets whether dragging the shuttle ring should cause the multiplier
     * to snap to the defined tick values rather than interpolating between them.
     * This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.snapToTicks = false;

    knockout.track(this, [
      "_allShuttleRingTicks",
      "_dateFormatter",
      "_timeFormatter",
      "shuttleRingDragging",
      "snapToTicks",
    ]);

    this._sortedFilteredPositiveTicks = [];

    this.setShuttleRingTicks(AnimationViewModel.defaultTicks);

    /**
     * Gets the string representation of the current time.  This property is observable.
     * @type {String}
     */
    this.timeLabel = undefined;
    knockout.defineProperty(this, "timeLabel", function () {
      return that._timeFormatter(that._clockViewModel.currentTime, that);
    });

    /**
     * Gets the string representation of the current date.  This property is observable.
     * @type {String}
     */
    this.dateLabel = undefined;
    knockout.defineProperty(this, "dateLabel", function () {
      return that._dateFormatter(that._clockViewModel.currentTime, that);
    });

    /**
     * Gets the string representation of the current multiplier.  This property is observable.
     * @type {String}
     */
    this.multiplierLabel = undefined;
    knockout.defineProperty(this, "multiplierLabel", function () {
      var clockViewModel = that._clockViewModel;
      if (clockViewModel.clockStep === ClockStep$1.SYSTEM_CLOCK) {
        return "Today";
      }

      var multiplier = clockViewModel.multiplier;

      //If it's a whole number, just return it.
      if (multiplier % 1 === 0) {
        return multiplier.toFixed(0) + "x";
      }

      //Convert to decimal string and remove any trailing zeroes
      return multiplier.toFixed(3).replace(/0{0,3}$/, "") + "x";
    });

    /**
     * Gets or sets the current shuttle ring angle.  This property is observable.
     * @type {Number}
     */
    this.shuttleRingAngle = undefined;
    knockout.defineProperty(this, "shuttleRingAngle", {
      get: function () {
        return multiplierToAngle(
          clockViewModel.multiplier,
          that._allShuttleRingTicks,
          clockViewModel
        );
      },
      set: function (angle) {
        angle = Math.max(
          Math.min(angle, maxShuttleRingAngle),
          -maxShuttleRingAngle
        );
        var ticks = that._allShuttleRingTicks;

        var clockViewModel = that._clockViewModel;
        clockViewModel.clockStep = ClockStep$1.SYSTEM_CLOCK_MULTIPLIER;

        //If we are at the max angle, simply return the max value in either direction.
        if (Math.abs(angle) === maxShuttleRingAngle) {
          clockViewModel.multiplier =
            angle > 0 ? ticks[ticks.length - 1] : ticks[0];
          return;
        }

        var multiplier = angleToMultiplier(angle, ticks);
        if (that.snapToTicks) {
          multiplier = ticks[getTypicalMultiplierIndex(multiplier, ticks)];
        } else if (multiplier !== 0) {
          var positiveMultiplier = Math.abs(multiplier);

          if (positiveMultiplier > 100) {
            var numDigits = positiveMultiplier.toFixed(0).length - 2;
            var divisor = Math.pow(10, numDigits);
            multiplier = (Math.round(multiplier / divisor) * divisor) | 0;
          } else if (positiveMultiplier > realtimeShuttleRingAngle) {
            multiplier = Math.round(multiplier);
          } else if (positiveMultiplier > 1) {
            multiplier = +multiplier.toFixed(1);
          } else if (positiveMultiplier > 0) {
            multiplier = +multiplier.toFixed(2);
          }
        }
        clockViewModel.multiplier = multiplier;
      },
    });

    this._canAnimate = undefined;
    knockout.defineProperty(this, "_canAnimate", function () {
      var clockViewModel = that._clockViewModel;
      var clockRange = clockViewModel.clockRange;

      if (that.shuttleRingDragging || clockRange === ClockRange$1.UNBOUNDED) {
        return true;
      }

      var multiplier = clockViewModel.multiplier;
      var currentTime = clockViewModel.currentTime;
      var startTime = clockViewModel.startTime;

      var result = false;
      if (clockRange === ClockRange$1.LOOP_STOP) {
        result =
          JulianDate.greaterThan(currentTime, startTime) ||
          (currentTime.equals(startTime) && multiplier > 0);
      } else {
        var stopTime = clockViewModel.stopTime;
        result =
          (JulianDate.greaterThan(currentTime, startTime) &&
            JulianDate.lessThan(currentTime, stopTime)) || //
          (currentTime.equals(startTime) && multiplier > 0) || //
          (currentTime.equals(stopTime) && multiplier < 0);
      }

      if (!result) {
        clockViewModel.shouldAnimate = false;
      }
      return result;
    });

    this._isSystemTimeAvailable = undefined;
    knockout.defineProperty(this, "_isSystemTimeAvailable", function () {
      var clockViewModel = that._clockViewModel;
      var clockRange = clockViewModel.clockRange;
      if (clockRange === ClockRange$1.UNBOUNDED) {
        return true;
      }

      var systemTime = clockViewModel.systemTime;
      return (
        JulianDate.greaterThanOrEquals(systemTime, clockViewModel.startTime) &&
        JulianDate.lessThanOrEquals(systemTime, clockViewModel.stopTime)
      );
    });

    this._isAnimating = undefined;
    knockout.defineProperty(this, "_isAnimating", function () {
      return (
        that._clockViewModel.shouldAnimate &&
        (that._canAnimate || that.shuttleRingDragging)
      );
    });

    var pauseCommand = createCommand$2(function () {
      var clockViewModel = that._clockViewModel;
      if (clockViewModel.shouldAnimate) {
        clockViewModel.shouldAnimate = false;
      } else if (that._canAnimate) {
        clockViewModel.shouldAnimate = true;
      }
    });

    this._pauseViewModel = new ToggleButtonViewModel(pauseCommand, {
      toggled: knockout.computed(function () {
        return !that._isAnimating;
      }),
      tooltip: "Pause",
    });

    var playReverseCommand = createCommand$2(function () {
      var clockViewModel = that._clockViewModel;
      var multiplier = clockViewModel.multiplier;
      if (multiplier > 0) {
        clockViewModel.multiplier = -multiplier;
      }
      clockViewModel.shouldAnimate = true;
    });

    this._playReverseViewModel = new ToggleButtonViewModel(playReverseCommand, {
      toggled: knockout.computed(function () {
        return that._isAnimating && clockViewModel.multiplier < 0;
      }),
      tooltip: "Play Reverse",
    });

    var playForwardCommand = createCommand$2(function () {
      var clockViewModel = that._clockViewModel;
      var multiplier = clockViewModel.multiplier;
      if (multiplier < 0) {
        clockViewModel.multiplier = -multiplier;
      }
      clockViewModel.shouldAnimate = true;
    });

    this._playForwardViewModel = new ToggleButtonViewModel(playForwardCommand, {
      toggled: knockout.computed(function () {
        return (
          that._isAnimating &&
          clockViewModel.multiplier > 0 &&
          clockViewModel.clockStep !== ClockStep$1.SYSTEM_CLOCK
        );
      }),
      tooltip: "Play Forward",
    });

    var playRealtimeCommand = createCommand$2(function () {
      that._clockViewModel.clockStep = ClockStep$1.SYSTEM_CLOCK;
    }, knockout.getObservable(this, "_isSystemTimeAvailable"));

    this._playRealtimeViewModel = new ToggleButtonViewModel(playRealtimeCommand, {
      toggled: knockout.computed(function () {
        return clockViewModel.clockStep === ClockStep$1.SYSTEM_CLOCK;
      }),
      tooltip: knockout.computed(function () {
        return that._isSystemTimeAvailable
          ? "Today (real-time)"
          : "Current time not in range";
      }),
    });

    this._slower = createCommand$2(function () {
      var clockViewModel = that._clockViewModel;
      var shuttleRingTicks = that._allShuttleRingTicks;
      var multiplier = clockViewModel.multiplier;
      var index = getTypicalMultiplierIndex(multiplier, shuttleRingTicks) - 1;
      if (index >= 0) {
        clockViewModel.multiplier = shuttleRingTicks[index];
      }
    });

    this._faster = createCommand$2(function () {
      var clockViewModel = that._clockViewModel;
      var shuttleRingTicks = that._allShuttleRingTicks;
      var multiplier = clockViewModel.multiplier;
      var index = getTypicalMultiplierIndex(multiplier, shuttleRingTicks) + 1;
      if (index < shuttleRingTicks.length) {
        clockViewModel.multiplier = shuttleRingTicks[index];
      }
    });
  }

  /**
   * Gets or sets the default date formatter used by new instances.
   *
   * @member
   * @type {AnimationViewModel.DateFormatter}
   */
  AnimationViewModel.defaultDateFormatter = function (date, viewModel) {
    var gregorianDate = JulianDate.toGregorianDate(date);
    return (
      monthNames[gregorianDate.month - 1] +
      " " +
      gregorianDate.day +
      " " +
      gregorianDate.year
    );
  };

  /**
   * Gets or sets the default array of known clock multipliers associated with new instances of the shuttle ring.
   * @type {Number[]}
   */
  AnimationViewModel.defaultTicks = [
    //
    0.001,
    0.002,
    0.005,
    0.01,
    0.02,
    0.05,
    0.1,
    0.25,
    0.5,
    1.0,
    2.0,
    5.0,
    10.0, //
    15.0,
    30.0,
    60.0,
    120.0,
    300.0,
    600.0,
    900.0,
    1800.0,
    3600.0,
    7200.0,
    14400.0, //
    21600.0,
    43200.0,
    86400.0,
    172800.0,
    345600.0,
    604800.0,
  ];

  /**
   * Gets or sets the default time formatter used by new instances.
   *
   * @member
   * @type {AnimationViewModel.TimeFormatter}
   */
  AnimationViewModel.defaultTimeFormatter = function (date, viewModel) {
    var gregorianDate = JulianDate.toGregorianDate(date);
    var millisecond = Math.round(gregorianDate.millisecond);
    if (Math.abs(viewModel._clockViewModel.multiplier) < 1) {
      return sprintf(
        "%02d:%02d:%02d.%03d",
        gregorianDate.hour,
        gregorianDate.minute,
        gregorianDate.second,
        millisecond
      );
    }
    return sprintf(
      "%02d:%02d:%02d UTC",
      gregorianDate.hour,
      gregorianDate.minute,
      gregorianDate.second
    );
  };

  /**
   * Gets a copy of the array of positive known clock multipliers to associate with the shuttle ring.
   *
   * @returns {Number[]} The array of known clock multipliers associated with the shuttle ring.
   */
  AnimationViewModel.prototype.getShuttleRingTicks = function () {
    return this._sortedFilteredPositiveTicks.slice(0);
  };

  /**
   * Sets the array of positive known clock multipliers to associate with the shuttle ring.
   * These values will have negative equivalents created for them and sets both the minimum
   * and maximum range of values for the shuttle ring as well as the values that are snapped
   * to when a single click is made.  The values need not be in order, as they will be sorted
   * automatically, and duplicate values will be removed.
   *
   * @param {Number[]} positiveTicks The list of known positive clock multipliers to associate with the shuttle ring.
   */
  AnimationViewModel.prototype.setShuttleRingTicks = function (positiveTicks) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(positiveTicks)) {
      throw new DeveloperError("positiveTicks is required.");
    }
    //>>includeEnd('debug');

    var i;
    var len;
    var tick;

    var hash = {};
    var sortedFilteredPositiveTicks = this._sortedFilteredPositiveTicks;
    sortedFilteredPositiveTicks.length = 0;
    for (i = 0, len = positiveTicks.length; i < len; ++i) {
      tick = positiveTicks[i];
      //filter duplicates
      if (!hash.hasOwnProperty(tick)) {
        hash[tick] = true;
        sortedFilteredPositiveTicks.push(tick);
      }
    }
    sortedFilteredPositiveTicks.sort(numberComparator);

    var allTicks = [];
    for (len = sortedFilteredPositiveTicks.length, i = len - 1; i >= 0; --i) {
      tick = sortedFilteredPositiveTicks[i];
      if (tick !== 0) {
        allTicks.push(-tick);
      }
    }
    Array.prototype.push.apply(allTicks, sortedFilteredPositiveTicks);

    this._allShuttleRingTicks = allTicks;
  };

  Object.defineProperties(AnimationViewModel.prototype, {
    /**
     * Gets a command that decreases the speed of animation.
     * @memberof AnimationViewModel.prototype
     * @type {Command}
     */
    slower: {
      get: function () {
        return this._slower;
      },
    },

    /**
     * Gets a command that increases the speed of animation.
     * @memberof AnimationViewModel.prototype
     * @type {Command}
     */
    faster: {
      get: function () {
        return this._faster;
      },
    },

    /**
     * Gets the clock view model.
     * @memberof AnimationViewModel.prototype
     *
     * @type {ClockViewModel}
     */
    clockViewModel: {
      get: function () {
        return this._clockViewModel;
      },
    },

    /**
     * Gets the pause toggle button view model.
     * @memberof AnimationViewModel.prototype
     *
     * @type {ToggleButtonViewModel}
     */
    pauseViewModel: {
      get: function () {
        return this._pauseViewModel;
      },
    },

    /**
     * Gets the reverse toggle button view model.
     * @memberof AnimationViewModel.prototype
     *
     * @type {ToggleButtonViewModel}
     */
    playReverseViewModel: {
      get: function () {
        return this._playReverseViewModel;
      },
    },

    /**
     * Gets the play toggle button view model.
     * @memberof AnimationViewModel.prototype
     *
     * @type {ToggleButtonViewModel}
     */
    playForwardViewModel: {
      get: function () {
        return this._playForwardViewModel;
      },
    },

    /**
     * Gets the realtime toggle button view model.
     * @memberof AnimationViewModel.prototype
     *
     * @type {ToggleButtonViewModel}
     */
    playRealtimeViewModel: {
      get: function () {
        return this._playRealtimeViewModel;
      },
    },

    /**
     * Gets or sets the function which formats a date for display.
     * @memberof AnimationViewModel.prototype
     *
     * @type {AnimationViewModel.DateFormatter}
     * @default AnimationViewModel.defaultDateFormatter
     */
    dateFormatter: {
      //TODO:@exception {DeveloperError} dateFormatter must be a function.
      get: function () {
        return this._dateFormatter;
      },
      set: function (dateFormatter) {
        //>>includeStart('debug', pragmas.debug);
        if (typeof dateFormatter !== "function") {
          throw new DeveloperError("dateFormatter must be a function");
        }
        //>>includeEnd('debug');

        this._dateFormatter = dateFormatter;
      },
    },

    /**
     * Gets or sets the function which formats a time for display.
     * @memberof AnimationViewModel.prototype
     *
     * @type {AnimationViewModel.TimeFormatter}
     * @default AnimationViewModel.defaultTimeFormatter
     */
    timeFormatter: {
      //TODO:@exception {DeveloperError} timeFormatter must be a function.
      get: function () {
        return this._timeFormatter;
      },
      set: function (timeFormatter) {
        //>>includeStart('debug', pragmas.debug);
        if (typeof timeFormatter !== "function") {
          throw new DeveloperError("timeFormatter must be a function");
        }
        //>>includeEnd('debug');

        this._timeFormatter = timeFormatter;
      },
    },
  });

  //Currently exposed for tests.
  AnimationViewModel._maxShuttleRingAngle = maxShuttleRingAngle;
  AnimationViewModel._realtimeShuttleRingAngle = realtimeShuttleRingAngle;

  /**
   * The view model for {@link BaseLayerPicker}.
   * @alias BaseLayerPickerViewModel
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Globe} options.globe The Globe to use.
   * @param {ProviderViewModel[]} [options.imageryProviderViewModels=[]] The array of ProviderViewModel instances to use for imagery.
   * @param {ProviderViewModel} [options.selectedImageryProviderViewModel] The view model for the current base imagery layer, if not supplied the first available imagery layer is used.
   * @param {ProviderViewModel[]} [options.terrainProviderViewModels=[]] The array of ProviderViewModel instances to use for terrain.
   * @param {ProviderViewModel} [options.selectedTerrainProviderViewModel] The view model for the current base terrain layer, if not supplied the first available terrain layer is used.
   *
   * @exception {DeveloperError} imageryProviderViewModels must be an array.
   * @exception {DeveloperError} terrainProviderViewModels must be an array.
   */
  function BaseLayerPickerViewModel(options) {
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var globe = options.globe;
    var imageryProviderViewModels = defaultValue(
      options.imageryProviderViewModels,
      []
    );
    var terrainProviderViewModels = defaultValue(
      options.terrainProviderViewModels,
      []
    );

    //>>includeStart('debug', pragmas.debug);
    if (!defined(globe)) {
      throw new DeveloperError("globe is required");
    }
    //>>includeEnd('debug');

    this._globe = globe;

    /**
     * Gets or sets an array of ProviderViewModel instances available for imagery selection.
     * This property is observable.
     * @type {ProviderViewModel[]}
     */
    this.imageryProviderViewModels = imageryProviderViewModels.slice(0);

    /**
     * Gets or sets an array of ProviderViewModel instances available for terrain selection.
     * This property is observable.
     * @type {ProviderViewModel[]}
     */
    this.terrainProviderViewModels = terrainProviderViewModels.slice(0);

    /**
     * Gets or sets whether the imagery selection drop-down is currently visible.
     * @type {Boolean}
     * @default false
     */
    this.dropDownVisible = false;

    knockout.track(this, [
      "imageryProviderViewModels",
      "terrainProviderViewModels",
      "dropDownVisible",
    ]);

    var imageryObservable = knockout.getObservable(
      this,
      "imageryProviderViewModels"
    );
    var imageryProviders = knockout.pureComputed(function () {
      var providers = imageryObservable();
      var categories = {};
      var i;
      for (i = 0; i < providers.length; i++) {
        var provider = providers[i];
        var category = provider.category;
        if (defined(categories[category])) {
          categories[category].push(provider);
        } else {
          categories[category] = [provider];
        }
      }
      var allCategoryNames = Object.keys(categories);

      var result = [];
      for (i = 0; i < allCategoryNames.length; i++) {
        var name = allCategoryNames[i];
        result.push({
          name: name,
          providers: categories[name],
        });
      }
      return result;
    });
    this._imageryProviders = imageryProviders;

    var terrainObservable = knockout.getObservable(
      this,
      "terrainProviderViewModels"
    );
    var terrainProviders = knockout.pureComputed(function () {
      var providers = terrainObservable();
      var categories = {};
      var i;
      for (i = 0; i < providers.length; i++) {
        var provider = providers[i];
        var category = provider.category;
        if (defined(categories[category])) {
          categories[category].push(provider);
        } else {
          categories[category] = [provider];
        }
      }
      var allCategoryNames = Object.keys(categories);

      var result = [];
      for (i = 0; i < allCategoryNames.length; i++) {
        var name = allCategoryNames[i];
        result.push({
          name: name,
          providers: categories[name],
        });
      }
      return result;
    });
    this._terrainProviders = terrainProviders;

    /**
     * Gets the button tooltip.  This property is observable.
     * @type {String}
     */
    this.buttonTooltip = undefined;
    knockout.defineProperty(this, "buttonTooltip", function () {
      var selectedImagery = this.selectedImagery;
      var selectedTerrain = this.selectedTerrain;

      var imageryTip = defined(selectedImagery)
        ? selectedImagery.name
        : undefined;
      var terrainTip = defined(selectedTerrain)
        ? selectedTerrain.name
        : undefined;

      if (defined(imageryTip) && defined(terrainTip)) {
        return imageryTip + "\n" + terrainTip;
      } else if (defined(imageryTip)) {
        return imageryTip;
      }
      return terrainTip;
    });

    /**
     * Gets the button background image.  This property is observable.
     * @type {String}
     */
    this.buttonImageUrl = undefined;
    knockout.defineProperty(this, "buttonImageUrl", function () {
      var selectedImagery = this.selectedImagery;
      if (defined(selectedImagery)) {
        return selectedImagery.iconUrl;
      }
    });

    /**
     * Gets or sets the currently selected imagery.  This property is observable.
     * @type {ProviderViewModel}
     * @default undefined
     */
    this.selectedImagery = undefined;
    var selectedImageryViewModel = knockout.observable();

    this._currentImageryProviders = [];
    knockout.defineProperty(this, "selectedImagery", {
      get: function () {
        return selectedImageryViewModel();
      },
      set: function (value) {
        if (selectedImageryViewModel() === value) {
          this.dropDownVisible = false;
          return;
        }

        var i;
        var currentImageryProviders = this._currentImageryProviders;
        var currentImageryProvidersLength = currentImageryProviders.length;
        var imageryLayers = this._globe.imageryLayers;
        var hadExistingBaseLayer = false;
        for (i = 0; i < currentImageryProvidersLength; i++) {
          var layersLength = imageryLayers.length;
          for (var x = 0; x < layersLength; x++) {
            var layer = imageryLayers.get(x);
            if (layer.imageryProvider === currentImageryProviders[i]) {
              imageryLayers.remove(layer);
              hadExistingBaseLayer = true;
              break;
            }
          }
        }

        if (defined(value)) {
          var newProviders = value.creationCommand();
          if (Array.isArray(newProviders)) {
            var newProvidersLength = newProviders.length;
            for (i = newProvidersLength - 1; i >= 0; i--) {
              imageryLayers.addImageryProvider(newProviders[i], 0);
            }
            this._currentImageryProviders = newProviders.slice(0);
          } else {
            this._currentImageryProviders = [newProviders];
            if (hadExistingBaseLayer) {
              imageryLayers.addImageryProvider(newProviders, 0);
            } else {
              var baseLayer = imageryLayers.get(0);
              if (defined(baseLayer)) {
                imageryLayers.remove(baseLayer);
              }
              imageryLayers.addImageryProvider(newProviders, 0);
            }
          }
        }
        selectedImageryViewModel(value);
        this.dropDownVisible = false;
      },
    });

    /**
     * Gets or sets the currently selected terrain.  This property is observable.
     * @type {ProviderViewModel}
     * @default undefined
     */
    this.selectedTerrain = undefined;
    var selectedTerrainViewModel = knockout.observable();

    knockout.defineProperty(this, "selectedTerrain", {
      get: function () {
        return selectedTerrainViewModel();
      },
      set: function (value) {
        if (selectedTerrainViewModel() === value) {
          this.dropDownVisible = false;
          return;
        }

        var newProvider;
        if (defined(value)) {
          newProvider = value.creationCommand();
        }

        this._globe.depthTestAgainstTerrain = !(
          newProvider instanceof EllipsoidTerrainProvider
        );
        this._globe.terrainProvider = newProvider;
        selectedTerrainViewModel(value);
        this.dropDownVisible = false;
      },
    });

    var that = this;
    this._toggleDropDown = createCommand$2(function () {
      that.dropDownVisible = !that.dropDownVisible;
    });

    this.selectedImagery = defaultValue(
      options.selectedImageryProviderViewModel,
      imageryProviderViewModels[0]
    );
    this.selectedTerrain = defaultValue(
      options.selectedTerrainProviderViewModel,
      terrainProviderViewModels[0]
    );
  }

  Object.defineProperties(BaseLayerPickerViewModel.prototype, {
    /**
     * Gets the command to toggle the visibility of the drop down.
     * @memberof BaseLayerPickerViewModel.prototype
     *
     * @type {Command}
     */
    toggleDropDown: {
      get: function () {
        return this._toggleDropDown;
      },
    },

    /**
     * Gets the globe.
     * @memberof BaseLayerPickerViewModel.prototype
     *
     * @type {Globe}
     */
    globe: {
      get: function () {
        return this._globe;
      },
    },
  });

  /**
   * <span style="display: block; text-align: center;">
   * <img src="Images/BaseLayerPicker.png" width="264" height="287" alt="" />
   * <br />BaseLayerPicker with its drop-panel open.
   * </span>
   * <br /><br />
   * The BaseLayerPicker is a single button widget that displays a panel of available imagery and
   * terrain providers.  When imagery is selected, the corresponding imagery layer is created and inserted
   * as the base layer of the imagery collection; removing the existing base.  When terrain is selected,
   * it replaces the current terrain provider.  Each item in the available providers list contains a name,
   * a representative icon, and a tooltip to display more information when hovered. The list is initially
   * empty, and must be configured before use, as illustrated in the below example.
   *
   * @alias BaseLayerPicker
   * @constructor
   *
   * @param {Element|String} container The parent HTML container node or ID for this widget.
   * @param {Object} options Object with the following properties:
   * @param {Globe} options.globe The Globe to use.
   * @param {ProviderViewModel[]} [options.imageryProviderViewModels=[]] The array of ProviderViewModel instances to use for imagery.
   * @param {ProviderViewModel} [options.selectedImageryProviderViewModel] The view model for the current base imagery layer, if not supplied the first available imagery layer is used.
   * @param {ProviderViewModel[]} [options.terrainProviderViewModels=[]] The array of ProviderViewModel instances to use for terrain.
   * @param {ProviderViewModel} [options.selectedTerrainProviderViewModel] The view model for the current base terrain layer, if not supplied the first available terrain layer is used.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   *
   * @example
   * // In HTML head, include a link to the BaseLayerPicker.css stylesheet,
   * // and in the body, include: <div id="baseLayerPickerContainer"
   * //   style="position:absolute;top:24px;right:24px;width:38px;height:38px;"></div>
   *
   * //Create the list of available providers we would like the user to select from.
   * //This example uses 3, OpenStreetMap, The Black Marble, and a single, non-streaming world image.
   * var imageryViewModels = [];
   * imageryViewModels.push(new Cesium.ProviderViewModel({
   *      name : 'Open\u00adStreet\u00adMap',
   *      iconUrl : Cesium.buildModuleUrl('Widgets/Images/ImageryProviders/openStreetMap.png'),
   *      tooltip : 'OpenStreetMap (OSM) is a collaborative project to create a free editable \
   * map of the world.\nhttp://www.openstreetmap.org',
   *      creationFunction : function() {
   *          return new Cesium.OpenStreetMapImageryProvider({
   *              url : 'https://a.tile.openstreetmap.org/'
   *          });
   *      }
   *  }));
   *
   *  imageryViewModels.push(new Cesium.ProviderViewModel({
   *      name : 'Earth at Night',
   *      iconUrl : Cesium.buildModuleUrl('Widgets/Images/ImageryProviders/blackMarble.png'),
   *      tooltip : 'The lights of cities and villages trace the outlines of civilization \
   * in this global view of the Earth at night as seen by NASA/NOAA\'s Suomi NPP satellite.',
   *      creationFunction : function() {
   *          return new Cesium.IonImageryProvider({ assetId: 3812 });
   *      }
   *  }));
   *
   *  imageryViewModels.push(new Cesium.ProviderViewModel({
   *      name : 'Natural Earth\u00a0II',
   *      iconUrl : Cesium.buildModuleUrl('Widgets/Images/ImageryProviders/naturalEarthII.png'),
   *      tooltip : 'Natural Earth II, darkened for contrast.\nhttp://www.naturalearthdata.com/',
   *      creationFunction : function() {
   *          return new Cesium.TileMapServiceImageryProvider({
   *              url : Cesium.buildModuleUrl('Assets/Textures/NaturalEarthII')
   *          });
   *      }
   *  }));
   *
   * //Create a CesiumWidget without imagery, if you haven't already done so.
   * var cesiumWidget = new Cesium.CesiumWidget('cesiumContainer', { imageryProvider: false });
   *
   * //Finally, create the baseLayerPicker widget using our view models.
   * var layers = cesiumWidget.imageryLayers;
   * var baseLayerPicker = new Cesium.BaseLayerPicker('baseLayerPickerContainer', {
   *     globe : cesiumWidget.scene.globe,
   *     imageryProviderViewModels : imageryViewModels
   * });
   *
   * @see TerrainProvider
   * @see ImageryProvider
   * @see ImageryLayerCollection
   */
  function BaseLayerPicker(container, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var viewModel = new BaseLayerPickerViewModel(options);

    var element = document.createElement("button");
    element.type = "button";
    element.className = "cesium-button cesium-toolbar-button";
    element.setAttribute(
      "data-bind",
      "\
attr: { title: buttonTooltip },\
click: toggleDropDown"
    );
    container.appendChild(element);

    var imgElement = document.createElement("img");
    imgElement.setAttribute("draggable", "false");
    imgElement.className = "cesium-baseLayerPicker-selected";
    imgElement.setAttribute(
      "data-bind",
      "\
attr: { src: buttonImageUrl }, visible: !!buttonImageUrl"
    );
    element.appendChild(imgElement);

    var dropPanel = document.createElement("div");
    dropPanel.className = "cesium-baseLayerPicker-dropDown";
    dropPanel.setAttribute(
      "data-bind",
      '\
css: { "cesium-baseLayerPicker-dropDown-visible" : dropDownVisible }'
    );
    container.appendChild(dropPanel);

    var imageryTitle = document.createElement("div");
    imageryTitle.className = "cesium-baseLayerPicker-sectionTitle";
    imageryTitle.setAttribute(
      "data-bind",
      "visible: imageryProviderViewModels.length > 0"
    );
    imageryTitle.innerHTML = "Imagery";
    dropPanel.appendChild(imageryTitle);

    var imagerySection = document.createElement("div");
    imagerySection.className = "cesium-baseLayerPicker-section";
    imagerySection.setAttribute("data-bind", "foreach: _imageryProviders");
    dropPanel.appendChild(imagerySection);

    var imageryCategories = document.createElement("div");
    imageryCategories.className = "cesium-baseLayerPicker-category";
    imagerySection.appendChild(imageryCategories);

    var categoryTitle = document.createElement("div");
    categoryTitle.className = "cesium-baseLayerPicker-categoryTitle";
    categoryTitle.setAttribute("data-bind", "text: name");
    imageryCategories.appendChild(categoryTitle);

    var imageryChoices = document.createElement("div");
    imageryChoices.className = "cesium-baseLayerPicker-choices";
    imageryChoices.setAttribute("data-bind", "foreach: providers");
    imageryCategories.appendChild(imageryChoices);

    var imageryProvider = document.createElement("div");
    imageryProvider.className = "cesium-baseLayerPicker-item";
    imageryProvider.setAttribute(
      "data-bind",
      '\
css: { "cesium-baseLayerPicker-selectedItem" : $data === $parents[1].selectedImagery },\
attr: { title: tooltip },\
visible: creationCommand.canExecute,\
click: function($data) { $parents[1].selectedImagery = $data; }'
    );
    imageryChoices.appendChild(imageryProvider);

    var providerIcon = document.createElement("img");
    providerIcon.className = "cesium-baseLayerPicker-itemIcon";
    providerIcon.setAttribute("data-bind", "attr: { src: iconUrl }");
    providerIcon.setAttribute("draggable", "false");
    imageryProvider.appendChild(providerIcon);

    var providerLabel = document.createElement("div");
    providerLabel.className = "cesium-baseLayerPicker-itemLabel";
    providerLabel.setAttribute("data-bind", "text: name");
    imageryProvider.appendChild(providerLabel);

    var terrainTitle = document.createElement("div");
    terrainTitle.className = "cesium-baseLayerPicker-sectionTitle";
    terrainTitle.setAttribute(
      "data-bind",
      "visible: terrainProviderViewModels.length > 0"
    );
    terrainTitle.innerHTML = "Terrain";
    dropPanel.appendChild(terrainTitle);

    var terrainSection = document.createElement("div");
    terrainSection.className = "cesium-baseLayerPicker-section";
    terrainSection.setAttribute("data-bind", "foreach: _terrainProviders");
    dropPanel.appendChild(terrainSection);

    var terrainCategories = document.createElement("div");
    terrainCategories.className = "cesium-baseLayerPicker-category";
    terrainSection.appendChild(terrainCategories);

    var terrainCategoryTitle = document.createElement("div");
    terrainCategoryTitle.className = "cesium-baseLayerPicker-categoryTitle";
    terrainCategoryTitle.setAttribute("data-bind", "text: name");
    terrainCategories.appendChild(terrainCategoryTitle);

    var terrainChoices = document.createElement("div");
    terrainChoices.className = "cesium-baseLayerPicker-choices";
    terrainChoices.setAttribute("data-bind", "foreach: providers");
    terrainCategories.appendChild(terrainChoices);

    var terrainProvider = document.createElement("div");
    terrainProvider.className = "cesium-baseLayerPicker-item";
    terrainProvider.setAttribute(
      "data-bind",
      '\
css: { "cesium-baseLayerPicker-selectedItem" : $data === $parents[1].selectedTerrain },\
attr: { title: tooltip },\
visible: creationCommand.canExecute,\
click: function($data) { $parents[1].selectedTerrain = $data; }'
    );
    terrainChoices.appendChild(terrainProvider);

    var terrainProviderIcon = document.createElement("img");
    terrainProviderIcon.className = "cesium-baseLayerPicker-itemIcon";
    terrainProviderIcon.setAttribute("data-bind", "attr: { src: iconUrl }");
    terrainProviderIcon.setAttribute("draggable", "false");
    terrainProvider.appendChild(terrainProviderIcon);

    var terrainProviderLabel = document.createElement("div");
    terrainProviderLabel.className = "cesium-baseLayerPicker-itemLabel";
    terrainProviderLabel.setAttribute("data-bind", "text: name");
    terrainProvider.appendChild(terrainProviderLabel);

    knockout.applyBindings(viewModel, element);
    knockout.applyBindings(viewModel, dropPanel);

    this._viewModel = viewModel;
    this._container = container;
    this._element = element;
    this._dropPanel = dropPanel;

    this._closeDropDown = function (e) {
      if (!(element.contains(e.target) || dropPanel.contains(e.target))) {
        viewModel.dropDownVisible = false;
      }
    };

    if (FeatureDetection.supportsPointerEvents()) {
      document.addEventListener("pointerdown", this._closeDropDown, true);
    } else {
      document.addEventListener("mousedown", this._closeDropDown, true);
      document.addEventListener("touchstart", this._closeDropDown, true);
    }
  }

  Object.defineProperties(BaseLayerPicker.prototype, {
    /**
     * Gets the parent container.
     * @memberof BaseLayerPicker.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof BaseLayerPicker.prototype
     *
     * @type {BaseLayerPickerViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  BaseLayerPicker.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  BaseLayerPicker.prototype.destroy = function () {
    if (FeatureDetection.supportsPointerEvents()) {
      document.removeEventListener("pointerdown", this._closeDropDown, true);
    } else {
      document.removeEventListener("mousedown", this._closeDropDown, true);
      document.removeEventListener("touchstart", this._closeDropDown, true);
    }

    knockout.cleanNode(this._element);
    knockout.cleanNode(this._dropPanel);
    this._container.removeChild(this._element);
    this._container.removeChild(this._dropPanel);
    return destroyObject(this);
  };

  /**
   * A view model that represents each item in the {@link BaseLayerPicker}.
   *
   * @alias ProviderViewModel
   * @constructor
   *
   * @param {Object} options The object containing all parameters.
   * @param {String} options.name The name of the layer.
   * @param {String} options.tooltip The tooltip to show when the item is moused over.
   * @param {String} options.iconUrl An icon representing the layer.
   * @param {String} [options.category] A category for the layer.
   * @param {ProviderViewModel.CreationFunction|Command} options.creationFunction A function or Command
   *        that creates one or more providers which will be added to the globe when this item is selected.
   *
   * @see BaseLayerPicker
   * @see ImageryProvider
   * @see TerrainProvider
   */
  function ProviderViewModel(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options.name)) {
      throw new DeveloperError("options.name is required.");
    }
    if (!defined(options.tooltip)) {
      throw new DeveloperError("options.tooltip is required.");
    }
    if (!defined(options.iconUrl)) {
      throw new DeveloperError("options.iconUrl is required.");
    }
    if (typeof options.creationFunction !== "function") {
      throw new DeveloperError("options.creationFunction is required.");
    }
    //>>includeEnd('debug');

    var creationCommand = options.creationFunction;
    if (!defined(creationCommand.canExecute)) {
      creationCommand = createCommand$2(creationCommand);
    }

    this._creationCommand = creationCommand;

    /**
     * Gets the display name.  This property is observable.
     * @type {String}
     */
    this.name = options.name;

    /**
     * Gets the tooltip.  This property is observable.
     * @type {String}
     */
    this.tooltip = options.tooltip;

    /**
     * Gets the icon.  This property is observable.
     * @type {String}
     */
    this.iconUrl = options.iconUrl;

    this._category = defaultValue(options.category, "");

    knockout.track(this, ["name", "tooltip", "iconUrl"]);
  }

  Object.defineProperties(ProviderViewModel.prototype, {
    /**
     * Gets the Command that creates one or more providers which will be added to
     * the globe when this item is selected.
     * @memberof ProviderViewModel.prototype
     * @memberof ProviderViewModel.prototype
     * @type {Command}
     * @readonly
     */
    creationCommand: {
      get: function () {
        return this._creationCommand;
      },
    },

    /**
     * Gets the category
     * @type {String}
     * @memberof ProviderViewModel.prototype
     * @readonly
     */
    category: {
      get: function () {
        return this._category;
      },
    },
  });

  /**
   * @private
   */
  function createDefaultImageryProviderViewModels() {
    var providerViewModels = [];
    providerViewModels.push(
      new ProviderViewModel({
        name: "Bing Maps Aerial",
        iconUrl: buildModuleUrl("Widgets/Images/ImageryProviders/bingAerial.png"),
        tooltip: "Bing Maps aerial imagery, provided by Cesium ion",
        category: "Cesium ion",
        creationFunction: function () {
          return createWorldImagery({
            style: IonWorldImageryStyle$1.AERIAL,
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Bing Maps Aerial with Labels",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/bingAerialLabels.png"
        ),
        tooltip: "Bing Maps aerial imagery with labels, provided by Cesium ion",
        category: "Cesium ion",
        creationFunction: function () {
          return createWorldImagery({
            style: IonWorldImageryStyle$1.AERIAL_WITH_LABELS,
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Bing Maps Roads",
        iconUrl: buildModuleUrl("Widgets/Images/ImageryProviders/bingRoads.png"),
        tooltip: "Bing Maps standard road maps, provided by Cesium ion",
        category: "Cesium ion",
        creationFunction: function () {
          return createWorldImagery({
            style: IonWorldImageryStyle$1.ROAD,
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "ESRI World Imagery",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/esriWorldImagery.png"
        ),
        tooltip:
          "\
World Imagery provides one meter or better satellite and aerial imagery in many parts of the world and lower resolution \
satellite imagery worldwide.  The map includes NASA Blue Marble: Next Generation 500m resolution imagery at small scales \
(above 1:1,000,000), i-cubed 15m eSAT imagery at medium-to-large scales (down to 1:70,000) for the world, and USGS 15m Landsat \
imagery for Antarctica. The map features 0.3m resolution imagery in the continental United States and 0.6m resolution imagery in \
parts of Western Europe from DigitalGlobe. In other parts of the world, 1 meter resolution imagery is available from GeoEye IKONOS, \
i-cubed Nationwide Prime, Getmapping, AeroGRID, IGN Spain, and IGP Portugal.  Additionally, imagery at different resolutions has been \
contributed by the GIS User Community.\nhttp://www.esri.com",
        category: "Other",
        creationFunction: function () {
          return new ArcGisMapServerImageryProvider({
            url:
              "https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer",
            enablePickFeatures: false,
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "ESRI World Street Map",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/esriWorldStreetMap.png"
        ),
        tooltip:
          "\
This worldwide street map presents highway-level data for the world. Street-level data includes the United States; much of \
Canada; Japan; most countries in Europe; Australia and New Zealand; India; parts of South America including Argentina, Brazil, \
Chile, Colombia, and Venezuela; Ghana; and parts of southern Africa including Botswana, Lesotho, Namibia, South Africa, and Swaziland.\n\
http://www.esri.com",
        category: "Other",
        creationFunction: function () {
          return new ArcGisMapServerImageryProvider({
            url:
              "https://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer",
            enablePickFeatures: false,
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "ESRI National Geographic",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/esriNationalGeographic.png"
        ),
        tooltip:
          "\
This web map contains the National Geographic World Map service. This map service is designed to be used as a general reference map \
for informational and educational purposes as well as a basemap by GIS professionals and other users for creating web maps and web \
mapping applications.\nhttp://www.esri.com",
        category: "Other",
        creationFunction: function () {
          return new ArcGisMapServerImageryProvider({
            url:
              "https://services.arcgisonline.com/ArcGIS/rest/services/NatGeo_World_Map/MapServer/",
            enablePickFeatures: false,
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Open\u00adStreet\u00adMap",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/openStreetMap.png"
        ),
        tooltip:
          "OpenStreetMap (OSM) is a collaborative project to create a free editable map \
of the world.\nhttp://www.openstreetmap.org",
        category: "Other",
        creationFunction: function () {
          return new OpenStreetMapImageryProvider({
            url: "https://a.tile.openstreetmap.org/",
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Stamen Watercolor",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/stamenWatercolor.png"
        ),
        tooltip:
          "Reminiscent of hand drawn maps, Stamen watercolor maps apply raster effect \
area washes and organic edges over a paper texture to add warm pop to any map.\nhttp://maps.stamen.com",
        category: "Other",
        creationFunction: function () {
          return new OpenStreetMapImageryProvider({
            url: "https://stamen-tiles.a.ssl.fastly.net/watercolor/",
            credit:
              "Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under CC BY SA.",
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Stamen Toner",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/stamenToner.png"
        ),
        tooltip: "A high contrast black and white map.\nhttp://maps.stamen.com",
        category: "Other",
        creationFunction: function () {
          return new OpenStreetMapImageryProvider({
            url: "https://stamen-tiles.a.ssl.fastly.net/toner/",
            credit:
              "Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under CC BY SA.",
          });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Sentinel-2",
        iconUrl: buildModuleUrl("Widgets/Images/ImageryProviders/sentinel-2.png"),
        tooltip:
          "Sentinel-2 cloudless by EOX IT Services GmbH (Contains modified Copernicus Sentinel data 2016 and 2017).",
        category: "Cesium ion",
        creationFunction: function () {
          return new IonImageryProvider({ assetId: 3954 });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Blue Marble",
        iconUrl: buildModuleUrl("Widgets/Images/ImageryProviders/blueMarble.png"),
        tooltip: "Blue Marble Next Generation July, 2004 imagery from NASA.",
        category: "Cesium ion",
        creationFunction: function () {
          return new IonImageryProvider({ assetId: 3845 });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Earth at night",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/earthAtNight.png"
        ),
        tooltip:
          "The Earth at night, also known as The Black Marble, is a 500 meter resolution global composite imagery layer released by NASA.",
        category: "Cesium ion",
        creationFunction: function () {
          return new IonImageryProvider({ assetId: 3812 });
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Natural Earth\u00a0II",
        iconUrl: buildModuleUrl(
          "Widgets/Images/ImageryProviders/naturalEarthII.png"
        ),
        tooltip:
          "Natural Earth II, darkened for contrast.\nhttp://www.naturalearthdata.com/",
        category: "Cesium ion",
        creationFunction: function () {
          return new TileMapServiceImageryProvider({
            url: buildModuleUrl("Assets/Textures/NaturalEarthII"),
          });
        },
      })
    );

    return providerViewModels;
  }

  /**
   * @private
   */
  function createDefaultTerrainProviderViewModels() {
    var providerViewModels = [];
    providerViewModels.push(
      new ProviderViewModel({
        name: "WGS84 Ellipsoid",
        iconUrl: buildModuleUrl("Widgets/Images/TerrainProviders/Ellipsoid.png"),
        tooltip: "WGS84 standard ellipsoid, also known as EPSG:4326",
        category: "Cesium ion",
        creationFunction: function () {
          return new EllipsoidTerrainProvider();
        },
      })
    );

    providerViewModels.push(
      new ProviderViewModel({
        name: "Cesium World Terrain",
        iconUrl: buildModuleUrl(
          "Widgets/Images/TerrainProviders/CesiumWorldTerrain.png"
        ),
        tooltip:
          "High-resolution global terrain tileset curated from several datasources and hosted by Cesium ion",
        category: "Cesium ion",
        creationFunction: function () {
          return createWorldTerrain({
            requestWaterMask: true,
            requestVertexNormals: true,
          });
        },
      })
    );

    return providerViewModels;
  }

  function getPickTileset(viewModel) {
    return function (e) {
      var pick = viewModel._scene.pick(e.position);
      if (defined(pick) && pick.primitive instanceof Cesium3DTileset) {
        viewModel.tileset = pick.primitive;
      }
      viewModel.pickActive = false;
    };
  }

  function selectTilesetOnHover(viewModel, value) {
    if (value) {
      viewModel._eventHandler.setInputAction(function (e) {
        var pick = viewModel._scene.pick(e.endPosition);
        if (defined(pick) && pick.primitive instanceof Cesium3DTileset) {
          viewModel.tileset = pick.primitive;
        }
      }, ScreenSpaceEventType$1.MOUSE_MOVE);
    } else {
      viewModel._eventHandler.removeInputAction(ScreenSpaceEventType$1.MOUSE_MOVE);

      // Restore hover-over selection to its current value
      // eslint-disable-next-line no-self-assign
      viewModel.picking = viewModel.picking;
    }
  }

  var stringOptions$1 = {
    maximumFractionDigits: 3,
  };

  function formatMemoryString$1(memorySizeInBytes) {
    var memoryInMegabytes = memorySizeInBytes / 1048576;
    if (memoryInMegabytes < 1.0) {
      return memoryInMegabytes.toLocaleString(undefined, stringOptions$1);
    }
    return Math.round(memoryInMegabytes).toLocaleString();
  }

  function getStatistics(tileset, isPick) {
    if (!defined(tileset)) {
      return "";
    }

    var statistics = isPick
      ? tileset._statisticsPerPass[Cesium3DTilePass$1.PICK]
      : tileset._statisticsPerPass[Cesium3DTilePass$1.RENDER];

    // Since the pick pass uses a smaller frustum around the pixel of interest,
    // the statistics will be different than the normal render pass.
    var s = '<ul class="cesium-cesiumInspector-statistics">';
    s +=
      // --- Rendering statistics
      "<li><strong>Visited: </strong>" +
      statistics.visited.toLocaleString() +
      "</li>" +
      // Number of commands returned is likely to be higher than the number of tiles selected
      // because of tiles that create multiple commands.
      "<li><strong>Selected: </strong>" +
      statistics.selected.toLocaleString() +
      "</li>" +
      // Number of commands executed is likely to be higher because of commands overlapping
      // multiple frustums.
      "<li><strong>Commands: </strong>" +
      statistics.numberOfCommands.toLocaleString() +
      "</li>";
    s += "</ul>";
    if (!isPick) {
      s += '<ul class="cesium-cesiumInspector-statistics">';
      s +=
        // --- Cache/loading statistics
        "<li><strong>Requests: </strong>" +
        statistics.numberOfPendingRequests.toLocaleString() +
        "</li>" +
        "<li><strong>Attempted: </strong>" +
        statistics.numberOfAttemptedRequests.toLocaleString() +
        "</li>" +
        "<li><strong>Processing: </strong>" +
        statistics.numberOfTilesProcessing.toLocaleString() +
        "</li>" +
        "<li><strong>Content Ready: </strong>" +
        statistics.numberOfTilesWithContentReady.toLocaleString() +
        "</li>" +
        // Total number of tiles includes tiles without content, so "Ready" may never reach
        // "Total."  Total also will increase when a tile with a tileset JSON content is loaded.
        "<li><strong>Total: </strong>" +
        statistics.numberOfTilesTotal.toLocaleString() +
        "</li>";
      s += "</ul>";
      s += '<ul class="cesium-cesiumInspector-statistics">';
      s +=
        // --- Features statistics
        "<li><strong>Features Selected: </strong>" +
        statistics.numberOfFeaturesSelected.toLocaleString() +
        "</li>" +
        "<li><strong>Features Loaded: </strong>" +
        statistics.numberOfFeaturesLoaded.toLocaleString() +
        "</li>" +
        "<li><strong>Points Selected: </strong>" +
        statistics.numberOfPointsSelected.toLocaleString() +
        "</li>" +
        "<li><strong>Points Loaded: </strong>" +
        statistics.numberOfPointsLoaded.toLocaleString() +
        "</li>" +
        "<li><strong>Triangles Selected: </strong>" +
        statistics.numberOfTrianglesSelected.toLocaleString() +
        "</li>";
      s += "</ul>";
      s += '<ul class="cesium-cesiumInspector-statistics">';
      s +=
        // --- Styling statistics
        "<li><strong>Tiles styled: </strong>" +
        statistics.numberOfTilesStyled.toLocaleString() +
        "</li>" +
        "<li><strong>Features styled: </strong>" +
        statistics.numberOfFeaturesStyled.toLocaleString() +
        "</li>";
      s += "</ul>";
      s += '<ul class="cesium-cesiumInspector-statistics">';
      s +=
        // --- Optimization statistics
        "<li><strong>Children Union Culled: </strong>" +
        statistics.numberOfTilesCulledWithChildrenUnion.toLocaleString() +
        "</li>";
      s += "</ul>";
      s += '<ul class="cesium-cesiumInspector-statistics">';
      s +=
        // --- Memory statistics
        "<li><strong>Geometry Memory (MB): </strong>" +
        formatMemoryString$1(statistics.geometryByteLength) +
        "</li>" +
        "<li><strong>Texture Memory (MB): </strong>" +
        formatMemoryString$1(statistics.texturesByteLength) +
        "</li>" +
        "<li><strong>Batch Table Memory (MB): </strong>" +
        formatMemoryString$1(statistics.batchTableByteLength) +
        "</li>";
      s += "</ul>";
    }
    return s;
  }

  var colorBlendModes = [
    {
      text: "Highlight",
      value: Cesium3DTileColorBlendMode$1.HIGHLIGHT,
    },
    {
      text: "Replace",
      value: Cesium3DTileColorBlendMode$1.REPLACE,
    },
    {
      text: "Mix",
      value: Cesium3DTileColorBlendMode$1.MIX,
    },
  ];

  var highlightColor$1 = new Color(1.0, 1.0, 0.0, 0.4);
  var scratchColor$l = new Color();
  var oldColor = new Color();

  /**
   * The view model for {@link Cesium3DTilesInspector}.
   * @alias Cesium3DTilesInspectorViewModel
   * @constructor
   *
   * @param {Scene} scene The scene instance to use.
   * @param {HTMLElement} performanceContainer The container for the performance display
   */
  function Cesium3DTilesInspectorViewModel(scene, performanceContainer) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("scene", scene);
    Check.typeOf.object("performanceContainer", performanceContainer);
    //>>includeEnd('debug');

    var that = this;
    var canvas = scene.canvas;
    this._eventHandler = new ScreenSpaceEventHandler(canvas);
    this._scene = scene;
    this._performanceContainer = performanceContainer;
    this._canvas = canvas;

    this._performanceDisplay = new PerformanceDisplay({
      container: performanceContainer,
    });

    this._statisticsText = "";
    this._pickStatisticsText = "";
    this._editorError = "";

    /**
     * Gets or sets the flag to enable performance display.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.performance = false;

    /**
     * Gets or sets the flag to show statistics.  This property is observable.
     *
     * @type {Boolean}
     * @default true
     */
    this.showStatistics = true;

    /**
     * Gets or sets the flag to show pick statistics.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showPickStatistics = true;

    /**
     * Gets or sets the flag to show the inspector.  This property is observable.
     *
     * @type {Boolean}
     * @default true
     */
    this.inspectorVisible = true;

    /**
     * Gets or sets the flag to show the tileset section.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.tilesetVisible = false;

    /**
     * Gets or sets the flag to show the display section.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.displayVisible = false;

    /**
     * Gets or sets the flag to show the update section.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.updateVisible = false;

    /**
     * Gets or sets the flag to show the logging section.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.loggingVisible = false;

    /**
     * Gets or sets the flag to show the style section.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.styleVisible = false;

    /**
     * Gets or sets the flag to show the tile info section.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.tileDebugLabelsVisible = false;

    /**
     * Gets or sets the flag to show the optimization info section. This property is observable.
     *
     * @type {Boolean}
     * @default false;
     */
    this.optimizationVisible = false;

    /**
     * Gets or sets the JSON for the tileset style.  This property is observable.
     *
     * @type {String}
     * @default '{}'
     */
    this.styleString = "{}";

    this._tileset = undefined;
    this._feature = undefined;
    this._tile = undefined;

    knockout.track(this, [
      "performance",
      "inspectorVisible",
      "_statisticsText",
      "_pickStatisticsText",
      "_editorError",
      "showPickStatistics",
      "showStatistics",
      "tilesetVisible",
      "displayVisible",
      "updateVisible",
      "loggingVisible",
      "styleVisible",
      "optimizationVisible",
      "tileDebugLabelsVisible",
      "styleString",
      "_feature",
      "_tile",
    ]);

    this._properties = knockout.observable({});
    /**
     * Gets the names of the properties in the tileset.  This property is observable.
     * @type {String[]}
     * @readonly
     */
    this.properties = [];
    knockout.defineProperty(this, "properties", function () {
      var names = [];
      var properties = that._properties();
      for (var prop in properties) {
        if (properties.hasOwnProperty(prop)) {
          names.push(prop);
        }
      }
      return names;
    });

    var dynamicScreenSpaceError = knockout.observable();
    knockout.defineProperty(this, "dynamicScreenSpaceError", {
      get: function () {
        return dynamicScreenSpaceError();
      },
      set: function (value) {
        dynamicScreenSpaceError(value);
        if (defined(that._tileset)) {
          that._tileset.dynamicScreenSpaceError = value;
        }
      },
    });
    /**
     * Gets or sets the flag to enable dynamic screen space error.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.dynamicScreenSpaceError = false;

    var colorBlendMode = knockout.observable();
    knockout.defineProperty(this, "colorBlendMode", {
      get: function () {
        return colorBlendMode();
      },
      set: function (value) {
        colorBlendMode(value);
        if (defined(that._tileset)) {
          that._tileset.colorBlendMode = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the color blend mode.  This property is observable.
     *
     * @type {Cesium3DTileColorBlendMode}
     * @default Cesium3DTileColorBlendMode.HIGHLIGHT
     */
    this.colorBlendMode = Cesium3DTileColorBlendMode$1.HIGHLIGHT;

    var showOnlyPickedTileDebugLabel = knockout.observable();
    var picking = knockout.observable();
    knockout.defineProperty(this, "picking", {
      get: function () {
        return picking();
      },
      set: function (value) {
        picking(value);
        if (value) {
          that._eventHandler.setInputAction(function (e) {
            var picked = scene.pick(e.endPosition);
            if (picked instanceof Cesium3DTileFeature) {
              // Picked a feature
              that.feature = picked;
              that.tile = picked.content.tile;
            } else if (defined(picked) && defined(picked.content)) {
              // Picked a tile
              that.feature = undefined;
              that.tile = picked.content.tile;
            } else {
              // Picked nothing
              that.feature = undefined;
              that.tile = undefined;
            }
            if (!defined(that._tileset)) {
              return;
            }
            if (
              showOnlyPickedTileDebugLabel &&
              defined(picked) &&
              defined(picked.content)
            ) {
              var position;
              if (scene.pickPositionSupported) {
                position = scene.pickPosition(e.endPosition);
                if (defined(position)) {
                  that._tileset.debugPickPosition = position;
                }
              }
              that._tileset.debugPickedTile = picked.content.tile;
            } else {
              that._tileset.debugPickedTile = undefined;
            }
            that._scene.requestRender();
          }, ScreenSpaceEventType$1.MOUSE_MOVE);
        } else {
          that.feature = undefined;
          that.tile = undefined;
          that._eventHandler.removeInputAction(ScreenSpaceEventType$1.MOUSE_MOVE);
        }
      },
    });
    /**
     * Gets or sets the flag to enable picking.  This property is observable.
     *
     * @type {Boolean}
     * @default true
     */
    this.picking = true;

    var colorize = knockout.observable();
    knockout.defineProperty(this, "colorize", {
      get: function () {
        return colorize();
      },
      set: function (value) {
        colorize(value);
        if (defined(that._tileset)) {
          that._tileset.debugColorizeTiles = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to colorize tiles.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.colorize = false;

    var wireframe = knockout.observable();
    knockout.defineProperty(this, "wireframe", {
      get: function () {
        return wireframe();
      },
      set: function (value) {
        wireframe(value);
        if (defined(that._tileset)) {
          that._tileset.debugWireframe = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to draw with wireframe.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.wireframe = false;

    var showBoundingVolumes = knockout.observable();
    knockout.defineProperty(this, "showBoundingVolumes", {
      get: function () {
        return showBoundingVolumes();
      },
      set: function (value) {
        showBoundingVolumes(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowBoundingVolume = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to show bounding volumes.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showBoundingVolumes = false;

    var showContentBoundingVolumes = knockout.observable();
    knockout.defineProperty(this, "showContentBoundingVolumes", {
      get: function () {
        return showContentBoundingVolumes();
      },
      set: function (value) {
        showContentBoundingVolumes(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowContentBoundingVolume = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to show content volumes.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showContentBoundingVolumes = false;

    var showRequestVolumes = knockout.observable();
    knockout.defineProperty(this, "showRequestVolumes", {
      get: function () {
        return showRequestVolumes();
      },
      set: function (value) {
        showRequestVolumes(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowViewerRequestVolume = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to show request volumes.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showRequestVolumes = false;

    var freezeFrame = knockout.observable();
    knockout.defineProperty(this, "freezeFrame", {
      get: function () {
        return freezeFrame();
      },
      set: function (value) {
        freezeFrame(value);
        if (defined(that._tileset)) {
          that._tileset.debugFreezeFrame = value;
          that._scene.debugShowFrustumPlanes = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to suspend updates.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.freezeFrame = false;

    knockout.defineProperty(this, "showOnlyPickedTileDebugLabel", {
      get: function () {
        return showOnlyPickedTileDebugLabel();
      },
      set: function (value) {
        showOnlyPickedTileDebugLabel(value);
        if (defined(that._tileset)) {
          that._tileset.debugPickedTileLabelOnly = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to show debug labels only for the currently picked tile.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showOnlyPickedTileDebugLabel = false;

    var showGeometricError = knockout.observable();
    knockout.defineProperty(this, "showGeometricError", {
      get: function () {
        return showGeometricError();
      },
      set: function (value) {
        showGeometricError(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowGeometricError = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to show tile geometric error.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showGeometricError = false;

    var showRenderingStatistics = knockout.observable();
    knockout.defineProperty(this, "showRenderingStatistics", {
      get: function () {
        return showRenderingStatistics();
      },
      set: function (value) {
        showRenderingStatistics(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowRenderingStatistics = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Displays the number of commands, points, triangles and features used per tile.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showRenderingStatistics = false;

    var showMemoryUsage = knockout.observable();
    knockout.defineProperty(this, "showMemoryUsage", {
      get: function () {
        return showMemoryUsage();
      },
      set: function (value) {
        showMemoryUsage(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowMemoryUsage = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Displays the memory used per tile.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showMemoryUsage = false;

    var showUrl = knockout.observable();
    knockout.defineProperty(this, "showUrl", {
      get: function () {
        return showUrl();
      },
      set: function (value) {
        showUrl(value);
        if (defined(that._tileset)) {
          that._tileset.debugShowUrl = value;
          that._scene.requestRender();
        }
      },
    });
    /**
     * Gets or sets the flag to show the tile url.  This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.showUrl = false;

    var maximumScreenSpaceError = knockout.observable();
    knockout.defineProperty(this, "maximumScreenSpaceError", {
      get: function () {
        return maximumScreenSpaceError();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          maximumScreenSpaceError(value);
          if (defined(that._tileset)) {
            that._tileset.maximumScreenSpaceError = value;
          }
        }
      },
    });
    /**
     * Gets or sets the maximum screen space error.  This property is observable.
     *
     * @type {Number}
     * @default 16
     */
    this.maximumScreenSpaceError = 16;

    var dynamicScreenSpaceErrorDensity = knockout.observable();
    knockout.defineProperty(this, "dynamicScreenSpaceErrorDensity", {
      get: function () {
        return dynamicScreenSpaceErrorDensity();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          dynamicScreenSpaceErrorDensity(value);
          if (defined(that._tileset)) {
            that._tileset.dynamicScreenSpaceErrorDensity = value;
          }
        }
      },
    });
    /**
     * Gets or sets the dynamic screen space error density.  This property is observable.
     *
     * @type {Number}
     * @default 0.00278
     */
    this.dynamicScreenSpaceErrorDensity = 0.00278;

    /**
     * Gets or sets the dynamic screen space error density slider value.
     * This allows the slider to be exponential because values tend to be closer to 0 than 1.
     * This property is observable.
     *
     * @type {Number}
     * @default 0.00278
     */
    this.dynamicScreenSpaceErrorDensitySliderValue = undefined;
    knockout.defineProperty(this, "dynamicScreenSpaceErrorDensitySliderValue", {
      get: function () {
        return Math.pow(dynamicScreenSpaceErrorDensity(), 1 / 6);
      },
      set: function (value) {
        dynamicScreenSpaceErrorDensity(Math.pow(value, 6));
      },
    });

    var dynamicScreenSpaceErrorFactor = knockout.observable();
    knockout.defineProperty(this, "dynamicScreenSpaceErrorFactor", {
      get: function () {
        return dynamicScreenSpaceErrorFactor();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          dynamicScreenSpaceErrorFactor(value);
          if (defined(that._tileset)) {
            that._tileset.dynamicScreenSpaceErrorFactor = value;
          }
        }
      },
    });
    /**
     * Gets or sets the dynamic screen space error factor.  This property is observable.
     *
     * @type {Number}
     * @default 4.0
     */
    this.dynamicScreenSpaceErrorFactor = 4.0;

    var pickTileset = getPickTileset(this);
    var pickActive = knockout.observable();
    knockout.defineProperty(this, "pickActive", {
      get: function () {
        return pickActive();
      },
      set: function (value) {
        pickActive(value);
        if (value) {
          that._eventHandler.setInputAction(
            pickTileset,
            ScreenSpaceEventType$1.LEFT_CLICK
          );
        } else {
          that._eventHandler.removeInputAction(ScreenSpaceEventType$1.LEFT_CLICK);
        }
      },
    });

    var pointCloudShading = knockout.observable();
    knockout.defineProperty(this, "pointCloudShading", {
      get: function () {
        return pointCloudShading();
      },
      set: function (value) {
        pointCloudShading(value);
        if (defined(that._tileset)) {
          that._tileset.pointCloudShading.attenuation = value;
        }
      },
    });
    /**
     * Gets or sets the flag to enable point cloud shading. This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.pointCloudShading = false;

    var geometricErrorScale = knockout.observable();
    knockout.defineProperty(this, "geometricErrorScale", {
      get: function () {
        return geometricErrorScale();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          geometricErrorScale(value);
          if (defined(that._tileset)) {
            that._tileset.pointCloudShading.geometricErrorScale = value;
          }
        }
      },
    });
    /**
     * Gets or sets the geometric error scale.  This property is observable.
     *
     * @type {Number}
     * @default 1.0
     */
    this.geometricErrorScale = 1.0;

    var maximumAttenuation = knockout.observable();
    knockout.defineProperty(this, "maximumAttenuation", {
      get: function () {
        return maximumAttenuation();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          maximumAttenuation(value);
          if (defined(that._tileset)) {
            that._tileset.pointCloudShading.maximumAttenuation =
              value === 0 ? undefined : value;
          }
        }
      },
    });
    /**
     * Gets or sets the maximum attenuation.  This property is observable.
     *
     * @type {Number}
     * @default 0
     */
    this.maximumAttenuation = 0;

    var baseResolution = knockout.observable();
    knockout.defineProperty(this, "baseResolution", {
      get: function () {
        return baseResolution();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          baseResolution(value);
          if (defined(that._tileset)) {
            that._tileset.pointCloudShading.baseResolution =
              value === 0 ? undefined : value;
          }
        }
      },
    });
    /**
     * Gets or sets the base resolution.  This property is observable.
     *
     * @type {Number}
     * @default 0
     */
    this.baseResolution = 0;

    var eyeDomeLighting = knockout.observable();
    knockout.defineProperty(this, "eyeDomeLighting", {
      get: function () {
        return eyeDomeLighting();
      },
      set: function (value) {
        eyeDomeLighting(value);
        if (defined(that._tileset)) {
          that._tileset.pointCloudShading.eyeDomeLighting = value;
        }
      },
    });
    /**
     * Gets or sets the flag to enable eye dome lighting. This property is observable.
     *
     * @type {Boolean}
     * @default false
     */
    this.eyeDomeLighting = false;

    var eyeDomeLightingStrength = knockout.observable();
    knockout.defineProperty(this, "eyeDomeLightingStrength", {
      get: function () {
        return eyeDomeLightingStrength();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          eyeDomeLightingStrength(value);
          if (defined(that._tileset)) {
            that._tileset.pointCloudShading.eyeDomeLightingStrength = value;
          }
        }
      },
    });
    /**
     * Gets or sets the eye dome lighting strength.  This property is observable.
     *
     * @type {Number}
     * @default 1.0
     */
    this.eyeDomeLightingStrength = 1.0;

    var eyeDomeLightingRadius = knockout.observable();
    knockout.defineProperty(this, "eyeDomeLightingRadius", {
      get: function () {
        return eyeDomeLightingRadius();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          eyeDomeLightingRadius(value);
          if (defined(that._tileset)) {
            that._tileset.pointCloudShading.eyeDomeLightingRadius = value;
          }
        }
      },
    });
    /**
     * Gets or sets the eye dome lighting radius.  This property is observable.
     *
     * @type {Number}
     * @default 1.0
     */
    this.eyeDomeLightingRadius = 1.0;

    /**
     * Gets or sets the pick state
     *
     * @type {Boolean}
     * @default false
     */
    this.pickActive = false;

    var skipLevelOfDetail = knockout.observable();
    knockout.defineProperty(this, "skipLevelOfDetail", {
      get: function () {
        return skipLevelOfDetail();
      },
      set: function (value) {
        skipLevelOfDetail(value);
        if (defined(that._tileset)) {
          that._tileset.skipLevelOfDetail = value;
        }
      },
    });
    /**
     * Gets or sets the flag to determine if level of detail skipping should be applied during the traversal.
     * This property is observable.
     * @type {Boolean}
     * @default true
     */
    this.skipLevelOfDetail = true;

    var skipScreenSpaceErrorFactor = knockout.observable();
    knockout.defineProperty(this, "skipScreenSpaceErrorFactor", {
      get: function () {
        return skipScreenSpaceErrorFactor();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          skipScreenSpaceErrorFactor(value);
          if (defined(that._tileset)) {
            that._tileset.skipScreenSpaceErrorFactor = value;
          }
        }
      },
    });
    /**
     * Gets or sets the multiplier defining the minimum screen space error to skip. This property is observable.
     * @type {Number}
     * @default 16
     */
    this.skipScreenSpaceErrorFactor = 16;

    var baseScreenSpaceError = knockout.observable();
    knockout.defineProperty(this, "baseScreenSpaceError", {
      get: function () {
        return baseScreenSpaceError();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          baseScreenSpaceError(value);
          if (defined(that._tileset)) {
            that._tileset.baseScreenSpaceError = value;
          }
        }
      },
    });
    /**
     * Gets or sets the screen space error that must be reached before skipping levels of detail. This property is observable.
     * @type {Number}
     * @default 1024
     */
    this.baseScreenSpaceError = 1024;

    var skipLevels = knockout.observable();
    knockout.defineProperty(this, "skipLevels", {
      get: function () {
        return skipLevels();
      },
      set: function (value) {
        value = Number(value);
        if (!isNaN(value)) {
          skipLevels(value);
          if (defined(that._tileset)) {
            that._tileset.skipLevels = value;
          }
        }
      },
    });
    /**
     * Gets or sets the constant defining the minimum number of levels to skip when loading tiles. This property is observable.
     * @type {Number}
     * @default 1
     */
    this.skipLevels = 1;

    var immediatelyLoadDesiredLevelOfDetail = knockout.observable();
    knockout.defineProperty(this, "immediatelyLoadDesiredLevelOfDetail", {
      get: function () {
        return immediatelyLoadDesiredLevelOfDetail();
      },
      set: function (value) {
        immediatelyLoadDesiredLevelOfDetail(value);
        if (defined(that._tileset)) {
          that._tileset.immediatelyLoadDesiredLevelOfDetail = value;
        }
      },
    });
    /**
     * Gets or sets the flag which, when true, only tiles that meet the maximum screen space error will ever be downloaded.
     * This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.immediatelyLoadDesiredLevelOfDetail = false;

    var loadSiblings = knockout.observable();
    knockout.defineProperty(this, "loadSiblings", {
      get: function () {
        return loadSiblings();
      },
      set: function (value) {
        loadSiblings(value);
        if (defined(that._tileset)) {
          that._tileset.loadSiblings = value;
        }
      },
    });
    /**
     * Gets or sets the flag which determines whether siblings of visible tiles are always downloaded during traversal.
     * This property is observable
     * @type {Boolean}
     * @default false
     */
    this.loadSiblings = false;

    this._style = undefined;
    this._shouldStyle = false;
    this._definedProperties = [
      "properties",
      "dynamicScreenSpaceError",
      "colorBlendMode",
      "picking",
      "colorize",
      "wireframe",
      "showBoundingVolumes",
      "showContentBoundingVolumes",
      "showRequestVolumes",
      "freezeFrame",
      "maximumScreenSpaceError",
      "dynamicScreenSpaceErrorDensity",
      "baseScreenSpaceError",
      "skipScreenSpaceErrorFactor",
      "skipLevelOfDetail",
      "skipLevels",
      "immediatelyLoadDesiredLevelOfDetail",
      "loadSiblings",
      "dynamicScreenSpaceErrorDensitySliderValue",
      "dynamicScreenSpaceErrorFactor",
      "pickActive",
      "showOnlyPickedTileDebugLabel",
      "showGeometricError",
      "showRenderingStatistics",
      "showMemoryUsage",
      "showUrl",
      "pointCloudShading",
      "geometricErrorScale",
      "maximumAttenuation",
      "baseResolution",
      "eyeDomeLighting",
      "eyeDomeLightingStrength",
      "eyeDomeLightingRadius",
    ];
    this._removePostRenderEvent = scene.postRender.addEventListener(function () {
      that._update();
    });

    if (!defined(this._tileset)) {
      selectTilesetOnHover(this, true);
    }
  }

  Object.defineProperties(Cesium3DTilesInspectorViewModel.prototype, {
    /**
     * Gets the scene
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {Scene}
     * @readonly
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },
    /**
     * Gets the performance container
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {HTMLElement}
     * @readonly
     */
    performanceContainer: {
      get: function () {
        return this._performanceContainer;
      },
    },

    /**
     * Gets the statistics text.  This property is observable.
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {String}
     * @readonly
     */
    statisticsText: {
      get: function () {
        return this._statisticsText;
      },
    },
    /**
     * Gets the pick statistics text.  This property is observable.
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {String}
     * @readonly
     */
    pickStatisticsText: {
      get: function () {
        return this._pickStatisticsText;
      },
    },

    /**
     * Gets the available blend modes
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {Object[]}
     * @readonly
     */
    colorBlendModes: {
      get: function () {
        return colorBlendModes;
      },
    },

    /**
     * Gets the editor error message
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {String}
     * @readonly
     */
    editorError: {
      get: function () {
        return this._editorError;
      },
    },

    /**
     * Gets or sets the tileset of the view model.
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {Cesium3DTileset}
     */
    tileset: {
      get: function () {
        return this._tileset;
      },
      set: function (tileset) {
        this._tileset = tileset;
        this._style = undefined;
        this.styleString = "{}";
        this.feature = undefined;
        this.tile = undefined;

        if (defined(tileset)) {
          var that = this;
          tileset.readyPromise.then(function (t) {
            if (!that.isDestroyed()) {
              that._properties(t.properties);
            }
          });

          // update tileset with existing settings
          var settings = [
            "colorize",
            "wireframe",
            "showBoundingVolumes",
            "showContentBoundingVolumes",
            "showRequestVolumes",
            "freezeFrame",
            "showOnlyPickedTileDebugLabel",
            "showGeometricError",
            "showRenderingStatistics",
            "showMemoryUsage",
            "showUrl",
          ];
          var length = settings.length;
          for (var i = 0; i < length; ++i) {
            var setting = settings[i];
            //eslint-disable-next-line no-self-assign
            this[setting] = this[setting];
          }

          // update view model with existing tileset settings
          this.maximumScreenSpaceError = tileset.maximumScreenSpaceError;
          this.dynamicScreenSpaceError = tileset.dynamicScreenSpaceError;
          this.dynamicScreenSpaceErrorDensity =
            tileset.dynamicScreenSpaceErrorDensity;
          this.dynamicScreenSpaceErrorFactor =
            tileset.dynamicScreenSpaceErrorFactor;
          this.colorBlendMode = tileset.colorBlendMode;
          this.skipLevelOfDetail = tileset.skipLevelOfDetail;
          this.skipScreenSpaceErrorFactor = tileset.skipScreenSpaceErrorFactor;
          this.baseScreenSpaceError = tileset.baseScreenSpaceError;
          this.skipLevels = tileset.skipLevels;
          this.immediatelyLoadDesiredLevelOfDetail =
            tileset.immediatelyLoadDesiredLevelOfDetail;
          this.loadSiblings = tileset.loadSiblings;

          var pointCloudShading = tileset.pointCloudShading;
          this.pointCloudShading = pointCloudShading.attenuation;
          this.geometricErrorScale = pointCloudShading.geometricErrorScale;
          this.maximumAttenuation = pointCloudShading.maximumAttenuation
            ? pointCloudShading.maximumAttenuation
            : 0.0;
          this.baseResolution = pointCloudShading.baseResolution
            ? pointCloudShading.baseResolution
            : 0.0;
          this.eyeDomeLighting = pointCloudShading.eyeDomeLighting;
          this.eyeDomeLightingStrength =
            pointCloudShading.eyeDomeLightingStrength;
          this.eyeDomeLightingRadius = pointCloudShading.eyeDomeLightingRadius;

          this._scene.requestRender();
        } else {
          this._properties({});
        }

        this._statisticsText = getStatistics(tileset, false);
        this._pickStatisticsText = getStatistics(tileset, true);
        selectTilesetOnHover(this, false);
      },
    },

    /**
     * Gets the current feature of the view model.
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {Cesium3DTileFeature}
     */
    feature: {
      get: function () {
        return this._feature;
      },
      set: function (feature) {
        if (this._feature === feature) {
          return;
        }
        var currentFeature = this._feature;
        if (defined(currentFeature) && !currentFeature.content.isDestroyed()) {
          // Restore original color to feature that is no longer selected
          if (!this.colorize && defined(this._style)) {
            currentFeature.color = defined(this._style.color)
              ? this._style.color.evaluateColor(currentFeature, scratchColor$l)
              : Color.WHITE;
          } else {
            currentFeature.color = oldColor;
          }
          this._scene.requestRender();
        }
        if (defined(feature)) {
          // Highlight new feature
          Color.clone(feature.color, oldColor);
          feature.color = highlightColor$1;
          this._scene.requestRender();
        }
        this._feature = feature;
      },
    },

    /**
     * Gets the current tile of the view model
     * @memberof Cesium3DTilesInspectorViewModel.prototype
     * @type {Cesium3DTile}
     */
    tile: {
      get: function () {
        return this._tile;
      },
      set: function (tile) {
        if (this._tile === tile) {
          return;
        }
        var currentTile = this._tile;

        if (
          defined(currentTile) &&
          !currentTile.isDestroyed() &&
          !hasFeatures(currentTile.content)
        ) {
          // Restore original color to tile that is no longer selected
          currentTile.color = oldColor;
          this._scene.requestRender();
        }

        if (defined(tile) && !hasFeatures(tile.content)) {
          // Highlight new tile
          Color.clone(tile.color, oldColor);
          tile.color = highlightColor$1;
          this._scene.requestRender();
        }
        this._tile = tile;
      },
    },
  });

  function hasFeatures(content) {
    if (content.featuresLength > 0) {
      return true;
    }
    var innerContents = content.innerContents;
    if (defined(innerContents)) {
      var length = innerContents.length;
      for (var i = 0; i < length; ++i) {
        if (!hasFeatures(innerContents[i])) {
          return false;
        }
      }
      return true;
    }
    return false;
  }

  /**
   * Toggles the pick tileset mode
   */
  Cesium3DTilesInspectorViewModel.prototype.togglePickTileset = function () {
    this.pickActive = !this.pickActive;
  };

  /**
   * Toggles the inspector visibility
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleInspector = function () {
    this.inspectorVisible = !this.inspectorVisible;
  };

  /**
   * Toggles the visibility of the tileset section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleTileset = function () {
    this.tilesetVisible = !this.tilesetVisible;
  };

  /**
   * Toggles the visibility of the display section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleDisplay = function () {
    this.displayVisible = !this.displayVisible;
  };

  /**
   * Toggles the visibility of the update section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleUpdate = function () {
    this.updateVisible = !this.updateVisible;
  };

  /**
   * Toggles the visibility of the logging section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleLogging = function () {
    this.loggingVisible = !this.loggingVisible;
  };

  /**
   * Toggles the visibility of the style section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleStyle = function () {
    this.styleVisible = !this.styleVisible;
  };

  /**
   * Toggles the visibility of the tile Debug Info section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleTileDebugLabels = function () {
    this.tileDebugLabelsVisible = !this.tileDebugLabelsVisible;
  };

  /**
   * Toggles the visibility of the optimization section
   */
  Cesium3DTilesInspectorViewModel.prototype.toggleOptimization = function () {
    this.optimizationVisible = !this.optimizationVisible;
  };

  /**
   * Trims tile cache
   */
  Cesium3DTilesInspectorViewModel.prototype.trimTilesCache = function () {
    if (defined(this._tileset)) {
      this._tileset.trimLoadedTiles();
    }
  };

  /**
   * Compiles the style in the style editor.
   */
  Cesium3DTilesInspectorViewModel.prototype.compileStyle = function () {
    var tileset = this._tileset;
    if (!defined(tileset) || this.styleString === JSON.stringify(tileset.style)) {
      return;
    }
    this._editorError = "";
    try {
      if (this.styleString.length === 0) {
        this.styleString = "{}";
      }
      this._style = new Cesium3DTileStyle(JSON.parse(this.styleString));
      this._shouldStyle = true;
      this._scene.requestRender();
    } catch (err) {
      this._editorError = err.toString();
    }

    // set feature again so pick coloring is set
    this.feature = this._feature;
    this.tile = this._tile;
  };

  /**
   * Handles key press events on the style editor.
   */
  Cesium3DTilesInspectorViewModel.prototype.styleEditorKeyPress = function (
    sender,
    event
  ) {
    if (event.keyCode === 9) {
      //tab
      event.preventDefault();
      var textArea = event.target;
      var start = textArea.selectionStart;
      var end = textArea.selectionEnd;
      var newEnd = end;
      var selected = textArea.value.slice(start, end);
      var lines = selected.split("\n");
      var length = lines.length;
      var i;
      if (!event.shiftKey) {
        for (i = 0; i < length; ++i) {
          lines[i] = "  " + lines[i];
          newEnd += 2;
        }
      } else {
        for (i = 0; i < length; ++i) {
          if (lines[i][0] === " ") {
            if (lines[i][1] === " ") {
              lines[i] = lines[i].substr(2);
              newEnd -= 2;
            } else {
              lines[i] = lines[i].substr(1);
              newEnd -= 1;
            }
          }
        }
      }
      var newText = lines.join("\n");
      textArea.value =
        textArea.value.slice(0, start) + newText + textArea.value.slice(end);
      textArea.selectionStart = start !== end ? start : newEnd;
      textArea.selectionEnd = newEnd;
    } else if (event.ctrlKey && (event.keyCode === 10 || event.keyCode === 13)) {
      //ctrl + enter
      this.compileStyle();
    }
    return true;
  };

  /**
   * Updates the values of view model
   * @private
   */
  Cesium3DTilesInspectorViewModel.prototype._update = function () {
    var tileset = this._tileset;

    if (this.performance) {
      this._performanceDisplay.update();
    }

    if (defined(tileset)) {
      if (tileset.isDestroyed()) {
        this.tile = undefined;
        this.feature = undefined;
        this.tileset = undefined;
        return;
      }

      var style = tileset.style;
      if (this._style !== tileset.style) {
        if (this._shouldStyle) {
          tileset.style = this._style;
          this._shouldStyle = false;
        } else {
          this._style = style;
          this.styleString = JSON.stringify(style.style, null, "  ");
        }
      }
    }
    if (this.showStatistics) {
      this._statisticsText = getStatistics(tileset, false);
      this._pickStatisticsText = getStatistics(tileset, true);
    }
  };

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  Cesium3DTilesInspectorViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  Cesium3DTilesInspectorViewModel.prototype.destroy = function () {
    this._eventHandler.destroy();
    this._removePostRenderEvent();

    var that = this;
    this._definedProperties.forEach(function (property) {
      knockout.getObservable(that, property).dispose();
    });

    return destroyObject(this);
  };

  /**
   * Generates an HTML string of the statistics
   *
   * @function
   * @param {Cesium3DTileset} tileset The tileset
   * @param {Boolean} isPick Whether this is getting the statistics for the pick pass
   * @returns {String} The formatted statistics
   */
  Cesium3DTilesInspectorViewModel.getStatistics = getStatistics;

  /**
   * Inspector widget to aid in debugging 3D Tiles
   *
   * @alias Cesium3DTilesInspector
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene the Scene instance to use.
   */
  function Cesium3DTilesInspector(container, scene) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("container", container);
    Check.typeOf.object("scene", scene);
    //>>includeEnd('debug');

    container = getElement(container);
    var element = document.createElement("div");
    var performanceContainer = document.createElement("div");
    performanceContainer.setAttribute("data-bind", "visible: performance");
    var viewModel = new Cesium3DTilesInspectorViewModel(
      scene,
      performanceContainer
    );

    this._viewModel = viewModel;
    this._container = container;
    this._element = element;

    var text = document.createElement("div");
    text.textContent = "3D Tiles Inspector";
    text.className = "cesium-cesiumInspector-button";
    text.setAttribute("data-bind", "click: toggleInspector");
    element.appendChild(text);
    element.className = "cesium-cesiumInspector cesium-3DTilesInspector";
    element.setAttribute(
      "data-bind",
      'css: { "cesium-cesiumInspector-visible" : inspectorVisible, "cesium-cesiumInspector-hidden" : !inspectorVisible}'
    );
    container.appendChild(element);

    var panel = document.createElement("div");
    this._panel = panel;
    panel.className = "cesium-cesiumInspector-dropDown";
    element.appendChild(panel);

    var createSection = InspectorShared.createSection;
    var createCheckbox = InspectorShared.createCheckbox;

    var tilesetPanelContents = createSection(
      panel,
      "Tileset",
      "tilesetVisible",
      "toggleTileset"
    );
    var displayPanelContents = createSection(
      panel,
      "Display",
      "displayVisible",
      "toggleDisplay"
    );
    var updatePanelContents = createSection(
      panel,
      "Update",
      "updateVisible",
      "toggleUpdate"
    );
    var loggingPanelContents = createSection(
      panel,
      "Logging",
      "loggingVisible",
      "toggleLogging"
    );
    var tileDebugLabelsPanelContents = createSection(
      panel,
      "Tile Debug Labels",
      "tileDebugLabelsVisible",
      "toggleTileDebugLabels"
    );
    var stylePanelContents = createSection(
      panel,
      "Style",
      "styleVisible",
      "toggleStyle"
    );
    var optimizationPanelContents = createSection(
      panel,
      "Optimization",
      "optimizationVisible",
      "toggleOptimization"
    );

    var properties = document.createElement("div");
    properties.className = "field-group";
    var propertiesLabel = document.createElement("label");
    propertiesLabel.className = "field-label";
    propertiesLabel.appendChild(document.createTextNode("Properties: "));
    var propertiesField = document.createElement("div");
    propertiesField.setAttribute("data-bind", "text: properties");
    properties.appendChild(propertiesLabel);
    properties.appendChild(propertiesField);
    tilesetPanelContents.appendChild(properties);
    tilesetPanelContents.appendChild(
      makeButton("togglePickTileset", "Pick Tileset", "pickActive")
    );
    tilesetPanelContents.appendChild(
      makeButton("trimTilesCache", "Trim Tiles Cache")
    );
    tilesetPanelContents.appendChild(createCheckbox("Enable Picking", "picking"));

    displayPanelContents.appendChild(createCheckbox("Colorize", "colorize"));
    displayPanelContents.appendChild(createCheckbox("Wireframe", "wireframe"));
    displayPanelContents.appendChild(
      createCheckbox("Bounding Volumes", "showBoundingVolumes")
    );
    displayPanelContents.appendChild(
      createCheckbox("Content Volumes", "showContentBoundingVolumes")
    );
    displayPanelContents.appendChild(
      createCheckbox("Request Volumes", "showRequestVolumes")
    );

    displayPanelContents.appendChild(
      createCheckbox("Point Cloud Shading", "pointCloudShading")
    );
    var pointCloudShadingContainer = document.createElement("div");
    pointCloudShadingContainer.setAttribute(
      "data-bind",
      "visible: pointCloudShading"
    );
    pointCloudShadingContainer.appendChild(
      makeRangeInput("geometricErrorScale", 0, 2, 0.01, "Geometric Error Scale")
    );
    pointCloudShadingContainer.appendChild(
      makeRangeInput("maximumAttenuation", 0, 32, 1, "Maximum Attenuation")
    );
    pointCloudShadingContainer.appendChild(
      makeRangeInput("baseResolution", 0, 1, 0.01, "Base Resolution")
    );
    pointCloudShadingContainer.appendChild(
      createCheckbox("Eye Dome Lighting (EDL)", "eyeDomeLighting")
    );
    displayPanelContents.appendChild(pointCloudShadingContainer);

    var edlContainer = document.createElement("div");
    edlContainer.setAttribute("data-bind", "visible: eyeDomeLighting");
    edlContainer.appendChild(
      makeRangeInput("eyeDomeLightingStrength", 0, 2.0, 0.1, "EDL Strength")
    );
    edlContainer.appendChild(
      makeRangeInput("eyeDomeLightingRadius", 0, 4.0, 0.1, "EDL Radius")
    );
    pointCloudShadingContainer.appendChild(edlContainer);

    updatePanelContents.appendChild(
      createCheckbox("Freeze Frame", "freezeFrame")
    );
    updatePanelContents.appendChild(
      createCheckbox("Dynamic Screen Space Error", "dynamicScreenSpaceError")
    );
    var sseContainer = document.createElement("div");
    sseContainer.appendChild(
      makeRangeInput(
        "maximumScreenSpaceError",
        0,
        128,
        1,
        "Maximum Screen Space Error"
      )
    );
    updatePanelContents.appendChild(sseContainer);
    var dynamicScreenSpaceErrorContainer = document.createElement("div");
    dynamicScreenSpaceErrorContainer.setAttribute(
      "data-bind",
      "visible: dynamicScreenSpaceError"
    );
    dynamicScreenSpaceErrorContainer.appendChild(
      makeRangeInput(
        "dynamicScreenSpaceErrorDensitySliderValue",
        0,
        1,
        0.005,
        "Screen Space Error Density",
        "dynamicScreenSpaceErrorDensity"
      )
    );
    dynamicScreenSpaceErrorContainer.appendChild(
      makeRangeInput(
        "dynamicScreenSpaceErrorFactor",
        1,
        10,
        0.1,
        "Screen Space Error Factor"
      )
    );
    updatePanelContents.appendChild(dynamicScreenSpaceErrorContainer);

    loggingPanelContents.appendChild(
      createCheckbox("Performance", "performance")
    );
    loggingPanelContents.appendChild(performanceContainer);
    loggingPanelContents.appendChild(
      createCheckbox("Statistics", "showStatistics")
    );
    var statistics = document.createElement("div");
    statistics.className = "cesium-3dTilesInspector-statistics";
    statistics.setAttribute(
      "data-bind",
      "html: statisticsText, visible: showStatistics"
    );
    loggingPanelContents.appendChild(statistics);
    loggingPanelContents.appendChild(
      createCheckbox("Pick Statistics", "showPickStatistics")
    );
    var pickStatistics = document.createElement("div");
    pickStatistics.className = "cesium-3dTilesInspector-statistics";
    pickStatistics.setAttribute(
      "data-bind",
      "html: pickStatisticsText, visible: showPickStatistics"
    );
    loggingPanelContents.appendChild(pickStatistics);

    var stylePanelEditor = document.createElement("div");
    stylePanelContents.appendChild(stylePanelEditor);
    stylePanelEditor.appendChild(document.createTextNode("Color Blend Mode: "));
    var blendDropdown = document.createElement("select");
    blendDropdown.setAttribute(
      "data-bind",
      "options: colorBlendModes, " +
        'optionsText: "text", ' +
        'optionsValue: "value", ' +
        "value: colorBlendMode"
    );
    stylePanelEditor.appendChild(blendDropdown);
    var styleEditor = document.createElement("textarea");
    styleEditor.setAttribute(
      "data-bind",
      "textInput: styleString, event: { keydown: styleEditorKeyPress }"
    );
    stylePanelEditor.className = "cesium-cesiumInspector-styleEditor";
    stylePanelEditor.appendChild(styleEditor);
    var closeStylesBtn = makeButton("compileStyle", "Compile (Ctrl+Enter)");
    stylePanelEditor.appendChild(closeStylesBtn);
    var errorBox = document.createElement("div");
    errorBox.className = "cesium-cesiumInspector-error";
    errorBox.setAttribute("data-bind", "text: editorError");
    stylePanelEditor.appendChild(errorBox);

    tileDebugLabelsPanelContents.appendChild(
      createCheckbox("Show Picked Only", "showOnlyPickedTileDebugLabel")
    );
    tileDebugLabelsPanelContents.appendChild(
      createCheckbox("Geometric Error", "showGeometricError")
    );
    tileDebugLabelsPanelContents.appendChild(
      createCheckbox("Rendering Statistics", "showRenderingStatistics")
    );
    tileDebugLabelsPanelContents.appendChild(
      createCheckbox("Memory Usage (MB)", "showMemoryUsage")
    );
    tileDebugLabelsPanelContents.appendChild(createCheckbox("Url", "showUrl"));

    optimizationPanelContents.appendChild(
      createCheckbox("Skip Tile LODs", "skipLevelOfDetail")
    );
    var skipScreenSpaceErrorFactorContainer = document.createElement("div");
    skipScreenSpaceErrorFactorContainer.appendChild(
      makeRangeInput("skipScreenSpaceErrorFactor", 1, 50, 1, "Skip SSE Factor")
    );
    optimizationPanelContents.appendChild(skipScreenSpaceErrorFactorContainer);
    var baseScreenSpaceError = document.createElement("div");
    baseScreenSpaceError.appendChild(
      makeRangeInput(
        "baseScreenSpaceError",
        0,
        4096,
        1,
        "SSE before skipping LOD"
      )
    );
    optimizationPanelContents.appendChild(baseScreenSpaceError);
    var skipLevelsContainer = document.createElement("div");
    skipLevelsContainer.appendChild(
      makeRangeInput("skipLevels", 0, 10, 1, "Min. levels to skip")
    );
    optimizationPanelContents.appendChild(skipLevelsContainer);
    optimizationPanelContents.appendChild(
      createCheckbox(
        "Load only tiles that meet the max SSE.",
        "immediatelyLoadDesiredLevelOfDetail"
      )
    );
    optimizationPanelContents.appendChild(
      createCheckbox("Load siblings of visible tiles", "loadSiblings")
    );

    knockout.applyBindings(viewModel, element);
  }

  Object.defineProperties(Cesium3DTilesInspector.prototype, {
    /**
     * Gets the parent container.
     * @memberof Cesium3DTilesInspector.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof Cesium3DTilesInspector.prototype
     *
     * @type {Cesium3DTilesInspectorViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  Cesium3DTilesInspector.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  Cesium3DTilesInspector.prototype.destroy = function () {
    knockout.cleanNode(this._element);
    this._container.removeChild(this._element);
    this.viewModel.destroy();

    return destroyObject(this);
  };

  function makeRangeInput(property, min, max, step, text, displayProperty) {
    displayProperty = defaultValue(displayProperty, property);
    var input = document.createElement("input");
    input.setAttribute("data-bind", "value: " + displayProperty);
    input.type = "number";

    var slider = document.createElement("input");
    slider.type = "range";
    slider.min = min;
    slider.max = max;
    slider.step = step;
    slider.setAttribute("data-bind", 'valueUpdate: "input", value: ' + property);

    var wrapper = document.createElement("div");
    wrapper.appendChild(slider);

    var container = document.createElement("div");
    container.className = "cesium-cesiumInspector-slider";
    container.appendChild(document.createTextNode(text));
    container.appendChild(input);
    container.appendChild(wrapper);

    return container;
  }

  function makeButton(action, text, active) {
    var button = document.createElement("button");
    button.type = "button";
    button.textContent = text;
    button.className = "cesium-cesiumInspector-pickButton";
    var binding = "click: " + action;
    if (defined(active)) {
      binding +=
        ', css: {"cesium-cesiumInspector-pickButtonHighlight" : ' + active + "}";
    }
    button.setAttribute("data-bind", binding);

    return button;
  }

  function frustumStatisticsToString(statistics) {
    var str;
    if (defined(statistics)) {
      str = "Command Statistics";
      var com = statistics.commandsInFrustums;
      for (var n in com) {
        if (com.hasOwnProperty(n)) {
          var num = parseInt(n, 10);
          var s;
          if (num === 7) {
            s = "1, 2 and 3";
          } else {
            var f = [];
            for (var i = 2; i >= 0; i--) {
              var p = Math.pow(2, i);
              if (num >= p) {
                f.push(i + 1);
                num -= p;
              }
            }
            s = f.reverse().join(" and ");
          }
          str += "<br>&nbsp;&nbsp;&nbsp;&nbsp;" + com[n] + " in frustum " + s;
        }
      }
      str += "<br>Total: " + statistics.totalCommands;
    }

    return str;
  }

  function boundDepthFrustum(lower, upper, proposed) {
    var bounded = Math.min(proposed, upper);
    bounded = Math.max(bounded, lower);
    return bounded;
  }

  var scratchPickRay$1 = new Ray();
  var scratchPickCartesian$1 = new Cartesian3();

  /**
   * The view model for {@link CesiumInspector}.
   * @alias CesiumInspectorViewModel
   * @constructor
   *
   * @param {Scene} scene The scene instance to use.
   * @param {Element} performanceContainer The instance to use for performance container.
   */
  function CesiumInspectorViewModel(scene, performanceContainer) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required");
    }

    if (!defined(performanceContainer)) {
      throw new DeveloperError("performanceContainer is required");
    }
    //>>includeEnd('debug');

    var that = this;
    var canvas = scene.canvas;
    var eventHandler = new ScreenSpaceEventHandler(canvas);
    this._eventHandler = eventHandler;
    this._scene = scene;
    this._canvas = canvas;
    this._primitive = undefined;
    this._tile = undefined;
    this._modelMatrixPrimitive = undefined;
    this._performanceDisplay = undefined;
    this._performanceContainer = performanceContainer;

    var globe = this._scene.globe;
    globe.depthTestAgainstTerrain = true;

    /**
     * Gets or sets the show frustums state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.frustums = false;

    /**
     * Gets or sets the show frustum planes state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.frustumPlanes = false;

    /**
     * Gets or sets the show performance display state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.performance = false;

    /**
     * Gets or sets the shader cache text.  This property is observable.
     * @type {String}
     * @default ''
     */
    this.shaderCacheText = "";

    /**
     * Gets or sets the show primitive bounding sphere state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.primitiveBoundingSphere = false;

    /**
     * Gets or sets the show primitive reference frame state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.primitiveReferenceFrame = false;

    /**
     * Gets or sets the filter primitive state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.filterPrimitive = false;

    /**
     * Gets or sets the show tile bounding sphere state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.tileBoundingSphere = false;

    /**
     * Gets or sets the filter tile state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.filterTile = false;

    /**
     * Gets or sets the show wireframe state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.wireframe = false;

    /**
     * Gets or sets the show globe depth state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.globeDepth = false;

    /**
     * Gets or sets the show pick depth state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.pickDepth = false;

    /**
     * Gets or sets the index of the depth frustum to display.  This property is observable.
     * @type {Number}
     * @default 1
     */
    this.depthFrustum = 1;
    this._numberOfFrustums = 1;

    /**
     * Gets or sets the suspend updates state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.suspendUpdates = false;

    /**
     * Gets or sets the show tile coordinates state.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.tileCoordinates = false;

    /**
     * Gets or sets the frustum statistic text.  This property is observable.
     * @type {String}
     * @default ''
     */
    this.frustumStatisticText = false;

    /**
     * Gets or sets the selected tile information text.  This property is observable.
     * @type {String}
     * @default ''
     */
    this.tileText = "";

    /**
     * Gets if a primitive has been selected.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.hasPickedPrimitive = false;

    /**
     * Gets if a tile has been selected.  This property is observable
     * @type {Boolean}
     * @default false
     */
    this.hasPickedTile = false;

    /**
     * Gets if the picking primitive command is active.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.pickPrimitiveActive = false;

    /**
     * Gets if the picking tile command is active.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.pickTileActive = false;

    /**
     * Gets or sets if the cesium inspector drop down is visible.  This property is observable.
     * @type {Boolean}
     * @default true
     */
    this.dropDownVisible = true;

    /**
     * Gets or sets if the general section is visible.  This property is observable.
     * @type {Boolean}
     * @default true
     */
    this.generalVisible = true;

    /**
     * Gets or sets if the primitive section is visible.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.primitivesVisible = false;

    /**
     * Gets or sets if the terrain section is visible.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.terrainVisible = false;

    /**
     * Gets or sets the index of the depth frustum text.  This property is observable.
     * @type {String}
     * @default ''
     */
    this.depthFrustumText = "";

    knockout.track(this, [
      "frustums",
      "frustumPlanes",
      "performance",
      "shaderCacheText",
      "primitiveBoundingSphere",
      "primitiveReferenceFrame",
      "filterPrimitive",
      "tileBoundingSphere",
      "filterTile",
      "wireframe",
      "globeDepth",
      "pickDepth",
      "depthFrustum",
      "suspendUpdates",
      "tileCoordinates",
      "frustumStatisticText",
      "tileText",
      "hasPickedPrimitive",
      "hasPickedTile",
      "pickPrimitiveActive",
      "pickTileActive",
      "dropDownVisible",
      "generalVisible",
      "primitivesVisible",
      "terrainVisible",
      "depthFrustumText",
    ]);

    this._toggleDropDown = createCommand$2(function () {
      that.dropDownVisible = !that.dropDownVisible;
    });

    this._toggleGeneral = createCommand$2(function () {
      that.generalVisible = !that.generalVisible;
    });

    this._togglePrimitives = createCommand$2(function () {
      that.primitivesVisible = !that.primitivesVisible;
    });

    this._toggleTerrain = createCommand$2(function () {
      that.terrainVisible = !that.terrainVisible;
    });

    this._frustumsSubscription = knockout
      .getObservable(this, "frustums")
      .subscribe(function (val) {
        that._scene.debugShowFrustums = val;
        that._scene.requestRender();
      });

    this._frustumPlanesSubscription = knockout
      .getObservable(this, "frustumPlanes")
      .subscribe(function (val) {
        that._scene.debugShowFrustumPlanes = val;
        that._scene.requestRender();
      });

    this._performanceSubscription = knockout
      .getObservable(this, "performance")
      .subscribe(function (val) {
        if (val) {
          that._performanceDisplay = new PerformanceDisplay({
            container: that._performanceContainer,
          });
        } else {
          that._performanceContainer.innerHTML = "";
        }
      });

    this._showPrimitiveBoundingSphere = createCommand$2(function () {
      that._primitive.debugShowBoundingVolume = that.primitiveBoundingSphere;
      that._scene.requestRender();
      return true;
    });

    this._primitiveBoundingSphereSubscription = knockout
      .getObservable(this, "primitiveBoundingSphere")
      .subscribe(function () {
        that._showPrimitiveBoundingSphere();
      });

    this._showPrimitiveReferenceFrame = createCommand$2(function () {
      if (that.primitiveReferenceFrame) {
        var modelMatrix = that._primitive.modelMatrix;
        that._modelMatrixPrimitive = new DebugModelMatrixPrimitive({
          modelMatrix: modelMatrix,
        });
        that._scene.primitives.add(that._modelMatrixPrimitive);
      } else if (defined(that._modelMatrixPrimitive)) {
        that._scene.primitives.remove(that._modelMatrixPrimitive);
        that._modelMatrixPrimitive = undefined;
      }
      that._scene.requestRender();
      return true;
    });

    this._primitiveReferenceFrameSubscription = knockout
      .getObservable(this, "primitiveReferenceFrame")
      .subscribe(function () {
        that._showPrimitiveReferenceFrame();
      });

    this._doFilterPrimitive = createCommand$2(function () {
      if (that.filterPrimitive) {
        that._scene.debugCommandFilter = function (command) {
          if (
            defined(that._modelMatrixPrimitive) &&
            command.owner === that._modelMatrixPrimitive._primitive
          ) {
            return true;
          } else if (defined(that._primitive)) {
            return (
              command.owner === that._primitive ||
              command.owner === that._primitive._billboardCollection ||
              command.owner.primitive === that._primitive
            );
          }
          return false;
        };
      } else {
        that._scene.debugCommandFilter = undefined;
      }
      return true;
    });

    this._filterPrimitiveSubscription = knockout
      .getObservable(this, "filterPrimitive")
      .subscribe(function () {
        that._doFilterPrimitive();
        that._scene.requestRender();
      });

    this._wireframeSubscription = knockout
      .getObservable(this, "wireframe")
      .subscribe(function (val) {
        globe._surface.tileProvider._debug.wireframe = val;
        that._scene.requestRender();
      });

    this._globeDepthSubscription = knockout
      .getObservable(this, "globeDepth")
      .subscribe(function (val) {
        that._scene.debugShowGlobeDepth = val;
        that._scene.requestRender();
      });

    this._pickDepthSubscription = knockout
      .getObservable(this, "pickDepth")
      .subscribe(function (val) {
        that._scene.debugShowPickDepth = val;
        that._scene.requestRender();
      });

    this._depthFrustumSubscription = knockout
      .getObservable(this, "depthFrustum")
      .subscribe(function (val) {
        that._scene.debugShowDepthFrustum = val;
        that._scene.requestRender();
      });

    this._incrementDepthFrustum = createCommand$2(function () {
      var next = that.depthFrustum + 1;
      that.depthFrustum = boundDepthFrustum(1, that._numberOfFrustums, next);
      that._scene.requestRender();
      return true;
    });

    this._decrementDepthFrustum = createCommand$2(function () {
      var next = that.depthFrustum - 1;
      that.depthFrustum = boundDepthFrustum(1, that._numberOfFrustums, next);
      that._scene.requestRender();
      return true;
    });

    this._suspendUpdatesSubscription = knockout
      .getObservable(this, "suspendUpdates")
      .subscribe(function (val) {
        globe._surface._debug.suspendLodUpdate = val;
        if (!val) {
          that.filterTile = false;
        }
      });

    var tileBoundariesLayer;
    this._showTileCoordinates = createCommand$2(function () {
      if (that.tileCoordinates && !defined(tileBoundariesLayer)) {
        tileBoundariesLayer = scene.imageryLayers.addImageryProvider(
          new TileCoordinatesImageryProvider({
            tilingScheme: scene.terrainProvider.tilingScheme,
          })
        );
      } else if (!that.tileCoordinates && defined(tileBoundariesLayer)) {
        scene.imageryLayers.remove(tileBoundariesLayer);
        tileBoundariesLayer = undefined;
      }
      return true;
    });

    this._tileCoordinatesSubscription = knockout
      .getObservable(this, "tileCoordinates")
      .subscribe(function () {
        that._showTileCoordinates();
        that._scene.requestRender();
      });

    this._tileBoundingSphereSubscription = knockout
      .getObservable(this, "tileBoundingSphere")
      .subscribe(function () {
        that._showTileBoundingSphere();
        that._scene.requestRender();
      });

    this._showTileBoundingSphere = createCommand$2(function () {
      if (that.tileBoundingSphere) {
        globe._surface.tileProvider._debug.boundingSphereTile = that._tile;
      } else {
        globe._surface.tileProvider._debug.boundingSphereTile = undefined;
      }
      that._scene.requestRender();
      return true;
    });

    this._doFilterTile = createCommand$2(function () {
      if (!that.filterTile) {
        that.suspendUpdates = false;
      } else {
        that.suspendUpdates = true;

        globe._surface._tilesToRender = [];

        if (defined(that._tile) && that._tile.renderable) {
          globe._surface._tilesToRender.push(that._tile);
        }
      }
      return true;
    });

    this._filterTileSubscription = knockout
      .getObservable(this, "filterTile")
      .subscribe(function () {
        that.doFilterTile();
        that._scene.requestRender();
      });

    function pickPrimitive(e) {
      var newPick = that._scene.pick({
        x: e.position.x,
        y: e.position.y,
      });
      if (defined(newPick)) {
        that.primitive = defined(newPick.collection)
          ? newPick.collection
          : newPick.primitive;
      }

      that._scene.requestRender();
      that.pickPrimitiveActive = false;
    }

    this._pickPrimitive = createCommand$2(function () {
      that.pickPrimitiveActive = !that.pickPrimitiveActive;
    });

    this._pickPrimitiveActiveSubscription = knockout
      .getObservable(this, "pickPrimitiveActive")
      .subscribe(function (val) {
        if (val) {
          eventHandler.setInputAction(
            pickPrimitive,
            ScreenSpaceEventType$1.LEFT_CLICK
          );
        } else {
          eventHandler.removeInputAction(ScreenSpaceEventType$1.LEFT_CLICK);
        }
      });

    function selectTile(e) {
      var selectedTile;
      var ellipsoid = globe.ellipsoid;

      var ray = that._scene.camera.getPickRay(e.position, scratchPickRay$1);
      var cartesian = globe.pick(ray, that._scene, scratchPickCartesian$1);

      if (defined(cartesian)) {
        var cartographic = ellipsoid.cartesianToCartographic(cartesian);
        var tilesRendered =
          globe._surface.tileProvider._tilesToRenderByTextureCount;
        for (
          var textureCount = 0;
          !selectedTile && textureCount < tilesRendered.length;
          ++textureCount
        ) {
          var tilesRenderedByTextureCount = tilesRendered[textureCount];
          if (!defined(tilesRenderedByTextureCount)) {
            continue;
          }

          for (
            var tileIndex = 0;
            !selectedTile && tileIndex < tilesRenderedByTextureCount.length;
            ++tileIndex
          ) {
            var tile = tilesRenderedByTextureCount[tileIndex];
            if (Rectangle.contains(tile.rectangle, cartographic)) {
              selectedTile = tile;
            }
          }
        }
      }

      that.tile = selectedTile;

      that.pickTileActive = false;
    }

    this._pickTile = createCommand$2(function () {
      that.pickTileActive = !that.pickTileActive;
    });

    this._pickTileActiveSubscription = knockout
      .getObservable(this, "pickTileActive")
      .subscribe(function (val) {
        if (val) {
          eventHandler.setInputAction(
            selectTile,
            ScreenSpaceEventType$1.LEFT_CLICK
          );
        } else {
          eventHandler.removeInputAction(ScreenSpaceEventType$1.LEFT_CLICK);
        }
      });

    this._removePostRenderEvent = scene.postRender.addEventListener(function () {
      that._update();
    });
  }

  Object.defineProperties(CesiumInspectorViewModel.prototype, {
    /**
     * Gets the scene to control.
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets the container of the PerformanceDisplay
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Element}
     */
    performanceContainer: {
      get: function () {
        return this._performanceContainer;
      },
    },

    /**
     * Gets the command to toggle the visibility of the drop down.
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    toggleDropDown: {
      get: function () {
        return this._toggleDropDown;
      },
    },

    /**
     * Gets the command to toggle the visibility of a BoundingSphere for a primitive
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    showPrimitiveBoundingSphere: {
      get: function () {
        return this._showPrimitiveBoundingSphere;
      },
    },

    /**
     * Gets the command to toggle the visibility of a {@link DebugModelMatrixPrimitive} for the model matrix of a primitive
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    showPrimitiveReferenceFrame: {
      get: function () {
        return this._showPrimitiveReferenceFrame;
      },
    },

    /**
     * Gets the command to toggle a filter that renders only a selected primitive
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    doFilterPrimitive: {
      get: function () {
        return this._doFilterPrimitive;
      },
    },

    /**
     * Gets the command to increment the depth frustum index to be shown
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    incrementDepthFrustum: {
      get: function () {
        return this._incrementDepthFrustum;
      },
    },

    /**
     * Gets the command to decrement the depth frustum index to be shown
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    decrementDepthFrustum: {
      get: function () {
        return this._decrementDepthFrustum;
      },
    },

    /**
     * Gets the command to toggle the visibility of tile coordinates
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    showTileCoordinates: {
      get: function () {
        return this._showTileCoordinates;
      },
    },

    /**
     * Gets the command to toggle the visibility of a BoundingSphere for a selected tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    showTileBoundingSphere: {
      get: function () {
        return this._showTileBoundingSphere;
      },
    },

    /**
     * Gets the command to toggle a filter that renders only a selected tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    doFilterTile: {
      get: function () {
        return this._doFilterTile;
      },
    },

    /**
     * Gets the command to expand and collapse the general section
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    toggleGeneral: {
      get: function () {
        return this._toggleGeneral;
      },
    },

    /**
     * Gets the command to expand and collapse the primitives section
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    togglePrimitives: {
      get: function () {
        return this._togglePrimitives;
      },
    },

    /**
     * Gets the command to expand and collapse the terrain section
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    toggleTerrain: {
      get: function () {
        return this._toggleTerrain;
      },
    },

    /**
     * Gets the command to pick a primitive
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    pickPrimitive: {
      get: function () {
        return this._pickPrimitive;
      },
    },

    /**
     * Gets the command to pick a tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    pickTile: {
      get: function () {
        return this._pickTile;
      },
    },

    /**
     * Gets the command to pick a tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    selectParent: {
      get: function () {
        var that = this;
        return createCommand$2(function () {
          that.tile = that.tile.parent;
        });
      },
    },

    /**
     * Gets the command to pick a tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    selectNW: {
      get: function () {
        var that = this;
        return createCommand$2(function () {
          that.tile = that.tile.northwestChild;
        });
      },
    },

    /**
     * Gets the command to pick a tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    selectNE: {
      get: function () {
        var that = this;
        return createCommand$2(function () {
          that.tile = that.tile.northeastChild;
        });
      },
    },

    /**
     * Gets the command to pick a tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    selectSW: {
      get: function () {
        var that = this;
        return createCommand$2(function () {
          that.tile = that.tile.southwestChild;
        });
      },
    },

    /**
     * Gets the command to pick a tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    selectSE: {
      get: function () {
        var that = this;
        return createCommand$2(function () {
          that.tile = that.tile.southeastChild;
        });
      },
    },

    /**
     * Gets or sets the current selected primitive
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    primitive: {
      get: function () {
        return this._primitive;
      },
      set: function (newPrimitive) {
        var oldPrimitive = this._primitive;
        if (newPrimitive !== oldPrimitive) {
          this.hasPickedPrimitive = true;
          if (defined(oldPrimitive)) {
            oldPrimitive.debugShowBoundingVolume = false;
          }
          this._scene.debugCommandFilter = undefined;
          if (defined(this._modelMatrixPrimitive)) {
            this._scene.primitives.remove(this._modelMatrixPrimitive);
            this._modelMatrixPrimitive = undefined;
          }
          this._primitive = newPrimitive;
          newPrimitive.show = false;
          setTimeout(function () {
            newPrimitive.show = true;
          }, 50);
          this.showPrimitiveBoundingSphere();
          this.showPrimitiveReferenceFrame();
          this.doFilterPrimitive();
        }
      },
    },

    /**
     * Gets or sets the current selected tile
     * @memberof CesiumInspectorViewModel.prototype
     *
     * @type {Command}
     */
    tile: {
      get: function () {
        return this._tile;
      },
      set: function (newTile) {
        if (defined(newTile)) {
          this.hasPickedTile = true;
          var oldTile = this._tile;
          if (newTile !== oldTile) {
            this.tileText =
              "L: " + newTile.level + " X: " + newTile.x + " Y: " + newTile.y;
            this.tileText +=
              "<br>SW corner: " +
              newTile.rectangle.west +
              ", " +
              newTile.rectangle.south;
            this.tileText +=
              "<br>NE corner: " +
              newTile.rectangle.east +
              ", " +
              newTile.rectangle.north;
            var data = newTile.data;
            if (defined(data) && defined(data.tileBoundingRegion)) {
              this.tileText +=
                "<br>Min: " +
                data.tileBoundingRegion.minimumHeight +
                " Max: " +
                data.tileBoundingRegion.maximumHeight;
            } else {
              this.tileText += "<br>(Tile is not loaded)";
            }
          }
          this._tile = newTile;
          this.showTileBoundingSphere();
          this.doFilterTile();
        } else {
          this.hasPickedTile = false;
          this._tile = undefined;
        }
      },
    },
  });

  /**
   * Updates the view model
   * @private
   */
  CesiumInspectorViewModel.prototype._update = function () {
    if (this.frustums) {
      this.frustumStatisticText = frustumStatisticsToString(
        this._scene.debugFrustumStatistics
      );
    }

    // Determine the number of frustums being used.
    var numberOfFrustums = this._scene.numberOfFrustums;
    this._numberOfFrustums = numberOfFrustums;
    // Bound the frustum to be displayed.
    this.depthFrustum = boundDepthFrustum(1, numberOfFrustums, this.depthFrustum);
    // Update the displayed text.
    this.depthFrustumText = this.depthFrustum + " of " + numberOfFrustums;

    if (this.performance) {
      this._performanceDisplay.update();
    }
    if (this.primitiveReferenceFrame) {
      this._modelMatrixPrimitive.modelMatrix = this._primitive.modelMatrix;
    }

    this.shaderCacheText =
      "Cached shaders: " + this._scene.context.shaderCache.numberOfShaders;
  };

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  CesiumInspectorViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  CesiumInspectorViewModel.prototype.destroy = function () {
    this._eventHandler.destroy();
    this._removePostRenderEvent();
    this._frustumsSubscription.dispose();
    this._frustumPlanesSubscription.dispose();
    this._performanceSubscription.dispose();
    this._primitiveBoundingSphereSubscription.dispose();
    this._primitiveReferenceFrameSubscription.dispose();
    this._filterPrimitiveSubscription.dispose();
    this._wireframeSubscription.dispose();
    this._globeDepthSubscription.dispose();
    this._pickDepthSubscription.dispose();
    this._depthFrustumSubscription.dispose();
    this._suspendUpdatesSubscription.dispose();
    this._tileCoordinatesSubscription.dispose();
    this._tileBoundingSphereSubscription.dispose();
    this._filterTileSubscription.dispose();
    this._pickPrimitiveActiveSubscription.dispose();
    this._pickTileActiveSubscription.dispose();
    return destroyObject(this);
  };

  /**
   * Inspector widget to aid in debugging
   *
   * @alias CesiumInspector
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene The Scene instance to use.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Cesium%20Inspector.html|Cesium Sandcastle Cesium Inspector Demo}
   */
  function CesiumInspector(container, scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }

    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var performanceContainer = document.createElement("div");

    var viewModel = new CesiumInspectorViewModel(scene, performanceContainer);
    this._viewModel = viewModel;
    this._container = container;

    var element = document.createElement("div");
    this._element = element;
    var text = document.createElement("div");
    text.textContent = "Cesium Inspector";
    text.className = "cesium-cesiumInspector-button";
    text.setAttribute("data-bind", "click: toggleDropDown");
    element.appendChild(text);
    element.className = "cesium-cesiumInspector";
    element.setAttribute(
      "data-bind",
      'css: { "cesium-cesiumInspector-visible" : dropDownVisible, "cesium-cesiumInspector-hidden" : !dropDownVisible }'
    );
    container.appendChild(this._element);

    var panel = document.createElement("div");
    this._panel = panel;
    panel.className = "cesium-cesiumInspector-dropDown";
    element.appendChild(panel);

    var createSection = InspectorShared.createSection;
    var createCheckbox = InspectorShared.createCheckbox;

    // General
    var generalSection = createSection(
      panel,
      "General",
      "generalVisible",
      "toggleGeneral"
    );

    var debugShowFrustums = createCheckbox("Show Frustums", "frustums");
    var frustumStatistics = document.createElement("div");
    frustumStatistics.className = "cesium-cesiumInspector-frustumStatistics";
    frustumStatistics.setAttribute(
      "data-bind",
      "visible: frustums, html: frustumStatisticText"
    );
    debugShowFrustums.appendChild(frustumStatistics);
    generalSection.appendChild(debugShowFrustums);

    generalSection.appendChild(
      createCheckbox("Show Frustum Planes", "frustumPlanes")
    );
    generalSection.appendChild(
      createCheckbox("Performance Display", "performance")
    );

    performanceContainer.className = "cesium-cesiumInspector-performanceDisplay";
    generalSection.appendChild(performanceContainer);

    var shaderCacheDisplay = document.createElement("div");
    shaderCacheDisplay.className = "cesium-cesiumInspector-shaderCache";
    shaderCacheDisplay.setAttribute("data-bind", "html: shaderCacheText");
    generalSection.appendChild(shaderCacheDisplay);

    // https://github.com/CesiumGS/cesium/issues/6763
    // var globeDepth = createCheckbox('Show globe depth', 'globeDepth');
    // generalSection.appendChild(globeDepth);
    //
    // var globeDepthFrustum = document.createElement('div');
    // globeDepth.appendChild(globeDepthFrustum);
    //
    // generalSection.appendChild(createCheckbox('Show pick depth', 'pickDepth'));

    var depthFrustum = document.createElement("div");
    generalSection.appendChild(depthFrustum);

    // Use a span with HTML binding so that we can indent with non-breaking spaces.
    var gLabel = document.createElement("span");
    gLabel.setAttribute(
      "data-bind",
      'html: "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Frustum:"'
    );
    depthFrustum.appendChild(gLabel);

    var gText = document.createElement("span");
    gText.setAttribute("data-bind", "text: depthFrustumText");
    depthFrustum.appendChild(gText);

    var gMinusButton = document.createElement("input");
    gMinusButton.type = "button";
    gMinusButton.value = "-";
    gMinusButton.className = "cesium-cesiumInspector-pickButton";
    gMinusButton.setAttribute("data-bind", "click: decrementDepthFrustum");
    depthFrustum.appendChild(gMinusButton);

    var gPlusButton = document.createElement("input");
    gPlusButton.type = "button";
    gPlusButton.value = "+";
    gPlusButton.className = "cesium-cesiumInspector-pickButton";
    gPlusButton.setAttribute("data-bind", "click: incrementDepthFrustum");
    depthFrustum.appendChild(gPlusButton);

    // Primitives
    var primSection = createSection(
      panel,
      "Primitives",
      "primitivesVisible",
      "togglePrimitives"
    );
    var pickPrimRequired = document.createElement("div");
    pickPrimRequired.className = "cesium-cesiumInspector-pickSection";
    primSection.appendChild(pickPrimRequired);

    var pickPrimitiveButton = document.createElement("input");
    pickPrimitiveButton.type = "button";
    pickPrimitiveButton.value = "Pick a primitive";
    pickPrimitiveButton.className = "cesium-cesiumInspector-pickButton";
    pickPrimitiveButton.setAttribute(
      "data-bind",
      'css: {"cesium-cesiumInspector-pickButtonHighlight" : pickPrimitiveActive}, click: pickPrimitive'
    );
    var buttonWrap = document.createElement("div");
    buttonWrap.className = "cesium-cesiumInspector-center";
    buttonWrap.appendChild(pickPrimitiveButton);
    pickPrimRequired.appendChild(buttonWrap);

    pickPrimRequired.appendChild(
      createCheckbox(
        "Show bounding sphere",
        "primitiveBoundingSphere",
        "hasPickedPrimitive"
      )
    );
    pickPrimRequired.appendChild(
      createCheckbox(
        "Show reference frame",
        "primitiveReferenceFrame",
        "hasPickedPrimitive"
      )
    );

    this._primitiveOnly = createCheckbox(
      "Show only selected",
      "filterPrimitive",
      "hasPickedPrimitive"
    );
    pickPrimRequired.appendChild(this._primitiveOnly);

    // Terrain
    var terrainSection = createSection(
      panel,
      "Terrain",
      "terrainVisible",
      "toggleTerrain"
    );
    var pickTileRequired = document.createElement("div");
    pickTileRequired.className = "cesium-cesiumInspector-pickSection";
    terrainSection.appendChild(pickTileRequired);
    var pickTileButton = document.createElement("input");
    pickTileButton.type = "button";
    pickTileButton.value = "Pick a tile";
    pickTileButton.className = "cesium-cesiumInspector-pickButton";
    pickTileButton.setAttribute(
      "data-bind",
      'css: {"cesium-cesiumInspector-pickButtonHighlight" : pickTileActive}, click: pickTile'
    );
    buttonWrap = document.createElement("div");
    buttonWrap.appendChild(pickTileButton);
    buttonWrap.className = "cesium-cesiumInspector-center";
    pickTileRequired.appendChild(buttonWrap);
    var tileInfo = document.createElement("div");
    pickTileRequired.appendChild(tileInfo);
    var parentTile = document.createElement("input");
    parentTile.type = "button";
    parentTile.value = "Parent";
    parentTile.className = "cesium-cesiumInspector-pickButton";
    parentTile.setAttribute("data-bind", "click: selectParent");
    var nwTile = document.createElement("input");
    nwTile.type = "button";
    nwTile.value = "NW";
    nwTile.className = "cesium-cesiumInspector-pickButton";
    nwTile.setAttribute("data-bind", "click: selectNW");
    var neTile = document.createElement("input");
    neTile.type = "button";
    neTile.value = "NE";
    neTile.className = "cesium-cesiumInspector-pickButton";
    neTile.setAttribute("data-bind", "click: selectNE");
    var swTile = document.createElement("input");
    swTile.type = "button";
    swTile.value = "SW";
    swTile.className = "cesium-cesiumInspector-pickButton";
    swTile.setAttribute("data-bind", "click: selectSW");
    var seTile = document.createElement("input");
    seTile.type = "button";
    seTile.value = "SE";
    seTile.className = "cesium-cesiumInspector-pickButton";
    seTile.setAttribute("data-bind", "click: selectSE");

    var tileText = document.createElement("div");
    tileText.className = "cesium-cesiumInspector-tileText";
    tileInfo.className = "cesium-cesiumInspector-frustumStatistics";
    tileInfo.appendChild(tileText);
    tileInfo.setAttribute("data-bind", "visible: hasPickedTile");
    tileText.setAttribute("data-bind", "html: tileText");

    var relativeText = document.createElement("div");
    relativeText.className = "cesium-cesiumInspector-relativeText";
    relativeText.textContent = "Select relative:";
    tileInfo.appendChild(relativeText);

    var table = document.createElement("table");
    var tr1 = document.createElement("tr");
    var tr2 = document.createElement("tr");
    var td1 = document.createElement("td");
    td1.appendChild(parentTile);
    var td2 = document.createElement("td");
    td2.appendChild(nwTile);
    var td3 = document.createElement("td");
    td3.appendChild(neTile);
    tr1.appendChild(td1);
    tr1.appendChild(td2);
    tr1.appendChild(td3);
    var td4 = document.createElement("td");
    var td5 = document.createElement("td");
    td5.appendChild(swTile);
    var td6 = document.createElement("td");
    td6.appendChild(seTile);
    tr2.appendChild(td4);
    tr2.appendChild(td5);
    tr2.appendChild(td6);
    table.appendChild(tr1);
    table.appendChild(tr2);

    tileInfo.appendChild(table);

    pickTileRequired.appendChild(
      createCheckbox(
        "Show bounding volume",
        "tileBoundingSphere",
        "hasPickedTile"
      )
    );
    pickTileRequired.appendChild(
      createCheckbox("Show only selected", "filterTile", "hasPickedTile")
    );

    terrainSection.appendChild(createCheckbox("Wireframe", "wireframe"));
    terrainSection.appendChild(
      createCheckbox("Suspend LOD update", "suspendUpdates")
    );
    terrainSection.appendChild(
      createCheckbox("Show tile coordinates", "tileCoordinates")
    );

    knockout.applyBindings(viewModel, this._element);
  }

  Object.defineProperties(CesiumInspector.prototype, {
    /**
     * Gets the parent container.
     * @memberof CesiumInspector.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof CesiumInspector.prototype
     *
     * @type {CesiumInspectorViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  CesiumInspector.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  CesiumInspector.prototype.destroy = function () {
    knockout.cleanNode(this._element);
    this._container.removeChild(this._element);
    this.viewModel.destroy();

    return destroyObject(this);
  };

  function getDefaultSkyBoxUrl(suffix) {
    return buildModuleUrl(
      "Assets/Textures/SkyBox/tycho2t3_80_" + suffix + ".jpg"
    );
  }

  function startRenderLoop(widget) {
    widget._renderLoopRunning = true;

    var lastFrameTime = 0;
    function render(frameTime) {
      if (widget.isDestroyed()) {
        return;
      }

      if (widget._useDefaultRenderLoop) {
        try {
          var targetFrameRate = widget._targetFrameRate;
          if (!defined(targetFrameRate)) {
            widget.resize();
            widget.render();
            requestAnimationFramePolyFill(render);
          } else {
            var interval = 1000.0 / targetFrameRate;
            var delta = frameTime - lastFrameTime;

            if (delta > interval) {
              widget.resize();
              widget.render();
              lastFrameTime = frameTime - (delta % interval);
            }
            requestAnimationFramePolyFill(render);
          }
        } catch (error) {
          widget._useDefaultRenderLoop = false;
          widget._renderLoopRunning = false;
          if (widget._showRenderLoopErrors) {
            var title =
              "An error occurred while rendering.  Rendering has stopped.";
            widget.showErrorPanel(title, undefined, error);
          }
        }
      } else {
        widget._renderLoopRunning = false;
      }
    }

    requestAnimationFramePolyFill(render);
  }

  function configurePixelRatio(widget) {
    var pixelRatio = widget._useBrowserRecommendedResolution
      ? 1.0
      : window.devicePixelRatio;
    pixelRatio *= widget._resolutionScale;
    if (defined(widget._scene)) {
      widget._scene.pixelRatio = pixelRatio;
    }

    return pixelRatio;
  }

  function configureCanvasSize(widget) {
    var canvas = widget._canvas;
    var width = canvas.clientWidth;
    var height = canvas.clientHeight;
    var pixelRatio = configurePixelRatio(widget);

    widget._canvasClientWidth = width;
    widget._canvasClientHeight = height;

    width *= pixelRatio;
    height *= pixelRatio;

    canvas.width = width;
    canvas.height = height;

    widget._canRender = width !== 0 && height !== 0;
    widget._lastDevicePixelRatio = window.devicePixelRatio;
  }

  function configureCameraFrustum(widget) {
    var canvas = widget._canvas;
    var width = canvas.width;
    var height = canvas.height;
    if (width !== 0 && height !== 0) {
      var frustum = widget._scene.camera.frustum;
      if (defined(frustum.aspectRatio)) {
        frustum.aspectRatio = width / height;
      } else {
        frustum.top = frustum.right * (height / width);
        frustum.bottom = -frustum.top;
      }
    }
  }

  /**
   * A widget containing a Cesium scene.
   *
   * @alias CesiumWidget
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Object} [options] Object with the following properties:
   * @param {Clock} [options.clock=new Clock()] The clock to use to control current time.
   * @param {ImageryProvider | false} [options.imageryProvider=createWorldImagery()] The imagery provider to serve as the base layer. If set to <code>false</code>, no imagery provider will be added.
   * @param {TerrainProvider} [options.terrainProvider=new EllipsoidTerrainProvider] The terrain provider.
   * @param {SkyBox| false} [options.skyBox] The skybox used to render the stars.  When <code>undefined</code>, the default stars are used. If set to <code>false</code>, no skyBox, Sun, or Moon will be added.
   * @param {SkyAtmosphere | false} [options.skyAtmosphere] Blue sky, and the glow around the Earth's limb.  Set to <code>false</code> to turn it off.
   * @param {SceneMode} [options.sceneMode=SceneMode.SCENE3D] The initial scene mode.
   * @param {Boolean} [options.scene3DOnly=false] When <code>true</code>, each geometry instance will only be rendered in 3D to save GPU memory.
   * @param {Boolean} [options.orderIndependentTranslucency=true] If true and the configuration supports it, use order independent translucency.
   * @param {MapProjection} [options.mapProjection=new GeographicProjection()] The map projection to use in 2D and Columbus View modes.
   * @param {Globe | false} [options.globe=new Globe(mapProjection.ellipsoid)] The globe to use in the scene.  If set to <code>false</code>, no globe will be added.
   * @param {Boolean} [options.useDefaultRenderLoop=true] True if this widget should control the render loop, false otherwise.
   * @param {Boolean} [options.useBrowserRecommendedResolution=true] If true, render at the browser's recommended resolution and ignore <code>window.devicePixelRatio</code>.
   * @param {Number} [options.targetFrameRate] The target frame rate when using the default render loop.
   * @param {Boolean} [options.showRenderLoopErrors=true] If true, this widget will automatically display an HTML panel to the user containing the error, if a render loop error occurs.
   * @param {Object} [options.contextOptions] Context and WebGL creation properties corresponding to <code>options</code> passed to {@link Scene}.
   * @param {Element|String} [options.creditContainer] The DOM element or ID that will contain the {@link CreditDisplay}.  If not specified, the credits are added
   *        to the bottom of the widget itself.
   * @param {Element|String} [options.creditViewport] The DOM element or ID that will contain the credit pop up created by the {@link CreditDisplay}.  If not specified, it will appear over the widget itself.
   * @param {Number} [options.terrainExaggeration=1.0] A scalar used to exaggerate the terrain. Note that terrain exaggeration will not modify any other primitive as they are positioned relative to the ellipsoid.
   * @param {Boolean} [options.shadows=false] Determines if shadows are cast by light sources.
   * @param {ShadowMode} [options.terrainShadows=ShadowMode.RECEIVE_ONLY] Determines if the terrain casts or receives shadows from light sources.
   * @param {MapMode2D} [options.mapMode2D=MapMode2D.INFINITE_SCROLL] Determines if the 2D map is rotatable or can be scrolled infinitely in the horizontal direction.
   * @param {Boolean} [options.requestRenderMode=false] If true, rendering a frame will only occur when needed as determined by changes within the scene. Enabling improves performance of the application, but requires using {@link Scene#requestRender} to render a new frame explicitly in this mode. This will be necessary in many cases after making changes to the scene in other parts of the API. See {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}.
   * @param {Number} [options.maximumRenderTimeChange=0.0] If requestRenderMode is true, this value defines the maximum change in simulation time allowed before a render is requested. See {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Cesium%20Widget.html|Cesium Sandcastle Cesium Widget Demo}
   *
   * @example
   * // For each example, include a link to CesiumWidget.css stylesheet in HTML head,
   * // and in the body, include: <div id="cesiumContainer"></div>
   *
   * //Widget with no terrain and default Bing Maps imagery provider.
   * var widget = new Cesium.CesiumWidget('cesiumContainer');
   *
   * //Widget with ion imagery and Cesium World Terrain.
   * var widget = new Cesium.CesiumWidget('cesiumContainer', {
   *     imageryProvider : Cesium.createWorldImagery(),
   *     terrainProvider : Cesium.createWorldTerrain(),
   *     skyBox : new Cesium.SkyBox({
   *         sources : {
   *           positiveX : 'stars/TychoSkymapII.t3_08192x04096_80_px.jpg',
   *           negativeX : 'stars/TychoSkymapII.t3_08192x04096_80_mx.jpg',
   *           positiveY : 'stars/TychoSkymapII.t3_08192x04096_80_py.jpg',
   *           negativeY : 'stars/TychoSkymapII.t3_08192x04096_80_my.jpg',
   *           positiveZ : 'stars/TychoSkymapII.t3_08192x04096_80_pz.jpg',
   *           negativeZ : 'stars/TychoSkymapII.t3_08192x04096_80_mz.jpg'
   *         }
   *     }),
   *     // Show Columbus View map with Web Mercator projection
   *     sceneMode : Cesium.SceneMode.COLUMBUS_VIEW,
   *     mapProjection : new Cesium.WebMercatorProjection()
   * });
   */
  function CesiumWidget(container, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //Configure the widget DOM elements
    var element = document.createElement("div");
    element.className = "cesium-widget";
    container.appendChild(element);

    var canvas = document.createElement("canvas");
    var supportsImageRenderingPixelated = FeatureDetection.supportsImageRenderingPixelated();
    this._supportsImageRenderingPixelated = supportsImageRenderingPixelated;
    if (supportsImageRenderingPixelated) {
      canvas.style.imageRendering = FeatureDetection.imageRenderingValue();
    }

    canvas.oncontextmenu = function () {
      return false;
    };
    canvas.onselectstart = function () {
      return false;
    };

    // Interacting with a canvas does not automatically blur the previously focused element.
    // This leads to unexpected interaction if the last element was an input field.
    // For example, clicking the mouse wheel could lead to the value in  the field changing
    // unexpectedly. The solution is to blur whatever has focus as soon as canvas interaction begins.
    function blurActiveElement() {
      if (canvas !== canvas.ownerDocument.activeElement) {
        canvas.ownerDocument.activeElement.blur();
      }
    }
    canvas.addEventListener("mousedown", blurActiveElement);
    canvas.addEventListener("pointerdown", blurActiveElement);

    element.appendChild(canvas);

    var innerCreditContainer = document.createElement("div");
    innerCreditContainer.className = "cesium-widget-credits";

    var creditContainer = defined(options.creditContainer)
      ? getElement(options.creditContainer)
      : element;
    creditContainer.appendChild(innerCreditContainer);

    var creditViewport = defined(options.creditViewport)
      ? getElement(options.creditViewport)
      : element;

    var showRenderLoopErrors = defaultValue(options.showRenderLoopErrors, true);

    var useBrowserRecommendedResolution = defaultValue(
      options.useBrowserRecommendedResolution,
      true
    );

    this._element = element;
    this._container = container;
    this._canvas = canvas;
    this._canvasClientWidth = 0;
    this._canvasClientHeight = 0;
    this._lastDevicePixelRatio = 0;
    this._creditViewport = creditViewport;
    this._creditContainer = creditContainer;
    this._innerCreditContainer = innerCreditContainer;
    this._canRender = false;
    this._renderLoopRunning = false;
    this._showRenderLoopErrors = showRenderLoopErrors;
    this._resolutionScale = 1.0;
    this._useBrowserRecommendedResolution = useBrowserRecommendedResolution;
    this._forceResize = false;
    this._clock = defined(options.clock) ? options.clock : new Clock();

    configureCanvasSize(this);

    try {
      var scene = new Scene({
        canvas: canvas,
        contextOptions: options.contextOptions,
        creditContainer: innerCreditContainer,
        creditViewport: creditViewport,
        mapProjection: options.mapProjection,
        orderIndependentTranslucency: options.orderIndependentTranslucency,
        scene3DOnly: defaultValue(options.scene3DOnly, false),
        terrainExaggeration: options.terrainExaggeration,
        shadows: options.shadows,
        mapMode2D: options.mapMode2D,
        requestRenderMode: options.requestRenderMode,
        maximumRenderTimeChange: options.maximumRenderTimeChange,
      });
      this._scene = scene;

      scene.camera.constrainedAxis = Cartesian3.UNIT_Z;

      configurePixelRatio(this);
      configureCameraFrustum(this);

      var ellipsoid = defaultValue(
        scene.mapProjection.ellipsoid,
        Ellipsoid.WGS84
      );

      var globe = options.globe;
      if (!defined(globe)) {
        globe = new Globe(ellipsoid);
      }
      if (globe !== false) {
        scene.globe = globe;
        scene.globe.shadows = defaultValue(
          options.terrainShadows,
          ShadowMode$1.RECEIVE_ONLY
        );
      }

      var skyBox = options.skyBox;
      if (!defined(skyBox)) {
        skyBox = new SkyBox({
          sources: {
            positiveX: getDefaultSkyBoxUrl("px"),
            negativeX: getDefaultSkyBoxUrl("mx"),
            positiveY: getDefaultSkyBoxUrl("py"),
            negativeY: getDefaultSkyBoxUrl("my"),
            positiveZ: getDefaultSkyBoxUrl("pz"),
            negativeZ: getDefaultSkyBoxUrl("mz"),
          },
        });
      }
      if (skyBox !== false) {
        scene.skyBox = skyBox;
        scene.sun = new Sun();
        scene.moon = new Moon();
      }

      // Blue sky, and the glow around the Earth's limb.
      var skyAtmosphere = options.skyAtmosphere;
      if (!defined(skyAtmosphere)) {
        skyAtmosphere = new SkyAtmosphere(ellipsoid);
      }
      if (skyAtmosphere !== false) {
        scene.skyAtmosphere = skyAtmosphere;
      }

      //Set the base imagery layer
      var imageryProvider =
        options.globe === false ? false : options.imageryProvider;
      if (!defined(imageryProvider)) {
        imageryProvider = createWorldImagery();
      }

      if (imageryProvider !== false) {
        scene.imageryLayers.addImageryProvider(imageryProvider);
      }

      //Set the terrain provider if one is provided.
      if (defined(options.terrainProvider) && options.globe !== false) {
        scene.terrainProvider = options.terrainProvider;
      }

      this._screenSpaceEventHandler = new ScreenSpaceEventHandler(canvas);

      if (defined(options.sceneMode)) {
        if (options.sceneMode === SceneMode$1.SCENE2D) {
          this._scene.morphTo2D(0);
        }
        if (options.sceneMode === SceneMode$1.COLUMBUS_VIEW) {
          this._scene.morphToColumbusView(0);
        }
      }

      this._useDefaultRenderLoop = undefined;
      this.useDefaultRenderLoop = defaultValue(
        options.useDefaultRenderLoop,
        true
      );

      this._targetFrameRate = undefined;
      this.targetFrameRate = options.targetFrameRate;

      var that = this;
      this._onRenderError = function (scene, error) {
        that._useDefaultRenderLoop = false;
        that._renderLoopRunning = false;
        if (that._showRenderLoopErrors) {
          var title =
            "An error occurred while rendering.  Rendering has stopped.";
          that.showErrorPanel(title, undefined, error);
        }
      };
      scene.renderError.addEventListener(this._onRenderError);
    } catch (error) {
      if (showRenderLoopErrors) {
        var title = "Error constructing CesiumWidget.";
        var message =
          'Visit <a href="http://get.webgl.org">http://get.webgl.org</a> to verify that your web browser and hardware support WebGL.  Consider trying a different web browser or updating your video drivers.  Detailed error information is below:';
        this.showErrorPanel(title, message, error);
      }
      throw error;
    }
  }

  Object.defineProperties(CesiumWidget.prototype, {
    /**
     * Gets the parent container.
     * @memberof CesiumWidget.prototype
     *
     * @type {Element}
     * @readonly
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the canvas.
     * @memberof CesiumWidget.prototype
     *
     * @type {HTMLCanvasElement}
     * @readonly
     */
    canvas: {
      get: function () {
        return this._canvas;
      },
    },

    /**
     * Gets the credit container.
     * @memberof CesiumWidget.prototype
     *
     * @type {Element}
     * @readonly
     */
    creditContainer: {
      get: function () {
        return this._creditContainer;
      },
    },

    /**
     * Gets the credit viewport
     * @memberof CesiumWidget.prototype
     *
     * @type {Element}
     * @readonly
     */
    creditViewport: {
      get: function () {
        return this._creditViewport;
      },
    },

    /**
     * Gets the scene.
     * @memberof CesiumWidget.prototype
     *
     * @type {Scene}
     * @readonly
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets the collection of image layers that will be rendered on the globe.
     * @memberof CesiumWidget.prototype
     *
     * @type {ImageryLayerCollection}
     * @readonly
     */
    imageryLayers: {
      get: function () {
        return this._scene.imageryLayers;
      },
    },

    /**
     * The terrain provider providing surface geometry for the globe.
     * @memberof CesiumWidget.prototype
     *
     * @type {TerrainProvider}
     */
    terrainProvider: {
      get: function () {
        return this._scene.terrainProvider;
      },
      set: function (terrainProvider) {
        this._scene.terrainProvider = terrainProvider;
      },
    },

    /**
     * Gets the camera.
     * @memberof CesiumWidget.prototype
     *
     * @type {Camera}
     * @readonly
     */
    camera: {
      get: function () {
        return this._scene.camera;
      },
    },

    /**
     * Gets the clock.
     * @memberof CesiumWidget.prototype
     *
     * @type {Clock}
     * @readonly
     */
    clock: {
      get: function () {
        return this._clock;
      },
    },

    /**
     * Gets the screen space event handler.
     * @memberof CesiumWidget.prototype
     *
     * @type {ScreenSpaceEventHandler}
     * @readonly
     */
    screenSpaceEventHandler: {
      get: function () {
        return this._screenSpaceEventHandler;
      },
    },

    /**
     * Gets or sets the target frame rate of the widget when <code>useDefaultRenderLoop</code>
     * is true. If undefined, the browser's {@link requestAnimationFrame} implementation
     * determines the frame rate.  If defined, this value must be greater than 0.  A value higher
     * than the underlying requestAnimationFrame implementation will have no effect.
     * @memberof CesiumWidget.prototype
     *
     * @type {Number}
     */
    targetFrameRate: {
      get: function () {
        return this._targetFrameRate;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (value <= 0) {
          throw new DeveloperError(
            "targetFrameRate must be greater than 0, or undefined."
          );
        }
        //>>includeEnd('debug');
        this._targetFrameRate = value;
      },
    },

    /**
     * Gets or sets whether or not this widget should control the render loop.
     * If set to true the widget will use {@link requestAnimationFrame} to
     * perform rendering and resizing of the widget, as well as drive the
     * simulation clock. If set to false, you must manually call the
     * <code>resize</code>, <code>render</code> methods as part of a custom
     * render loop.  If an error occurs during rendering, {@link Scene}'s
     * <code>renderError</code> event will be raised and this property
     * will be set to false.  It must be set back to true to continue rendering
     * after the error.
     * @memberof CesiumWidget.prototype
     *
     * @type {Boolean}
     */
    useDefaultRenderLoop: {
      get: function () {
        return this._useDefaultRenderLoop;
      },
      set: function (value) {
        if (this._useDefaultRenderLoop !== value) {
          this._useDefaultRenderLoop = value;
          if (value && !this._renderLoopRunning) {
            startRenderLoop(this);
          }
        }
      },
    },

    /**
     * Gets or sets a scaling factor for rendering resolution.  Values less than 1.0 can improve
     * performance on less powerful devices while values greater than 1.0 will render at a higher
     * resolution and then scale down, resulting in improved visual fidelity.
     * For example, if the widget is laid out at a size of 640x480, setting this value to 0.5
     * will cause the scene to be rendered at 320x240 and then scaled up while setting
     * it to 2.0 will cause the scene to be rendered at 1280x960 and then scaled down.
     * @memberof CesiumWidget.prototype
     *
     * @type {Number}
     * @default 1.0
     */
    resolutionScale: {
      get: function () {
        return this._resolutionScale;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (value <= 0) {
          throw new DeveloperError("resolutionScale must be greater than 0.");
        }
        //>>includeEnd('debug');
        if (this._resolutionScale !== value) {
          this._resolutionScale = value;
          this._forceResize = true;
        }
      },
    },

    /**
     * Boolean flag indicating if the browser's recommended resolution is used.
     * If true, the browser's device pixel ratio is ignored and 1.0 is used instead,
     * effectively rendering based on CSS pixels instead of device pixels. This can improve
     * performance on less powerful devices that have high pixel density. When false, rendering
     * will be in device pixels. {@link CesiumWidget#resolutionScale} will still take effect whether
     * this flag is true or false.
     * @memberof CesiumWidget.prototype
     *
     * @type {Boolean}
     * @default true
     */
    useBrowserRecommendedResolution: {
      get: function () {
        return this._useBrowserRecommendedResolution;
      },
      set: function (value) {
        if (this._useBrowserRecommendedResolution !== value) {
          this._useBrowserRecommendedResolution = value;
          this._forceResize = true;
        }
      },
    },
  });

  /**
   * Show an error panel to the user containing a title and a longer error message,
   * which can be dismissed using an OK button.  This panel is displayed automatically
   * when a render loop error occurs, if showRenderLoopErrors was not false when the
   * widget was constructed.
   *
   * @param {String} title The title to be displayed on the error panel.  This string is interpreted as text.
   * @param {String} [message] A helpful, user-facing message to display prior to the detailed error information.  This string is interpreted as HTML.
   * @param {String} [error] The error to be displayed on the error panel.  This string is formatted using {@link formatError} and then displayed as text.
   */
  CesiumWidget.prototype.showErrorPanel = function (title, message, error) {
    var element = this._element;
    var overlay = document.createElement("div");
    overlay.className = "cesium-widget-errorPanel";

    var content = document.createElement("div");
    content.className = "cesium-widget-errorPanel-content";
    overlay.appendChild(content);

    var errorHeader = document.createElement("div");
    errorHeader.className = "cesium-widget-errorPanel-header";
    errorHeader.appendChild(document.createTextNode(title));
    content.appendChild(errorHeader);

    var errorPanelScroller = document.createElement("div");
    errorPanelScroller.className = "cesium-widget-errorPanel-scroll";
    content.appendChild(errorPanelScroller);
    function resizeCallback() {
      errorPanelScroller.style.maxHeight =
        Math.max(Math.round(element.clientHeight * 0.9 - 100), 30) + "px";
    }
    resizeCallback();
    if (defined(window.addEventListener)) {
      window.addEventListener("resize", resizeCallback, false);
    }

    var hasMessage = defined(message);
    var hasError = defined(error);

    if (hasMessage || hasError) {
      var errorMessage = document.createElement("div");
      errorMessage.className = "cesium-widget-errorPanel-message";
      errorPanelScroller.appendChild(errorMessage);

      if (hasError) {
        var errorDetails = formatError(error);
        if (!hasMessage) {
          if (typeof error === "string") {
            error = new Error(error);
          }

          message = formatError({
            name: error.name,
            message: error.message,
          });
          errorDetails = error.stack;
        }

        //IE8 does not have a console object unless the dev tools are open.
        if (typeof console !== "undefined") {
          console.error(title + "\n" + message + "\n" + errorDetails);
        }

        var errorMessageDetails = document.createElement("div");
        errorMessageDetails.className =
          "cesium-widget-errorPanel-message-details collapsed";

        var moreDetails = document.createElement("span");
        moreDetails.className = "cesium-widget-errorPanel-more-details";
        moreDetails.appendChild(document.createTextNode("See more..."));
        errorMessageDetails.appendChild(moreDetails);

        errorMessageDetails.onclick = function (e) {
          errorMessageDetails.removeChild(moreDetails);
          errorMessageDetails.appendChild(document.createTextNode(errorDetails));
          errorMessageDetails.className =
            "cesium-widget-errorPanel-message-details";
          content.className = "cesium-widget-errorPanel-content expanded";
          errorMessageDetails.onclick = undefined;
        };

        errorPanelScroller.appendChild(errorMessageDetails);
      }

      errorMessage.innerHTML = "<p>" + message + "</p>";
    }

    var buttonPanel = document.createElement("div");
    buttonPanel.className = "cesium-widget-errorPanel-buttonPanel";
    content.appendChild(buttonPanel);

    var okButton = document.createElement("button");
    okButton.setAttribute("type", "button");
    okButton.className = "cesium-button";
    okButton.appendChild(document.createTextNode("OK"));
    okButton.onclick = function () {
      if (defined(resizeCallback) && defined(window.removeEventListener)) {
        window.removeEventListener("resize", resizeCallback, false);
      }
      element.removeChild(overlay);
    };

    buttonPanel.appendChild(okButton);

    element.appendChild(overlay);
  };

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  CesiumWidget.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  CesiumWidget.prototype.destroy = function () {
    if (defined(this._scene)) {
      this._scene.renderError.removeEventListener(this._onRenderError);
      this._scene = this._scene.destroy();
    }
    this._container.removeChild(this._element);
    this._creditContainer.removeChild(this._innerCreditContainer);
    destroyObject(this);
  };

  /**
   * Updates the canvas size, camera aspect ratio, and viewport size.
   * This function is called automatically as needed unless
   * <code>useDefaultRenderLoop</code> is set to false.
   */
  CesiumWidget.prototype.resize = function () {
    var canvas = this._canvas;
    if (
      !this._forceResize &&
      this._canvasClientWidth === canvas.clientWidth &&
      this._canvasClientHeight === canvas.clientHeight &&
      this._lastDevicePixelRatio === window.devicePixelRatio
    ) {
      return;
    }
    this._forceResize = false;

    configureCanvasSize(this);
    configureCameraFrustum(this);

    this._scene.requestRender();
  };

  /**
   * Renders the scene.  This function is called automatically
   * unless <code>useDefaultRenderLoop</code> is set to false;
   */
  CesiumWidget.prototype.render = function () {
    if (this._canRender) {
      this._scene.initializeFrame();
      var currentTime = this._clock.tick();
      this._scene.render(currentTime);
    } else {
      this._clock.tick();
    }
  };

  /**
   * The view model for {@link FullscreenButton}.
   * @alias FullscreenButtonViewModel
   * @constructor
   *
   * @param {Element|String} [fullscreenElement=document.body] The element or id to be placed into fullscreen mode.
   * @param {Element|String} [container] The DOM element or ID that will contain the widget.
   */
  function FullscreenButtonViewModel(fullscreenElement, container) {
    if (!defined(container)) {
      container = document.body;
    }

    container = getElement(container);

    var that = this;

    var tmpIsFullscreen = knockout.observable(Fullscreen.fullscreen);
    var tmpIsEnabled = knockout.observable(Fullscreen.enabled);
    var ownerDocument = container.ownerDocument;

    /**
     * Gets whether or not fullscreen mode is active.  This property is observable.
     *
     * @type {Boolean}
     */
    this.isFullscreen = undefined;
    knockout.defineProperty(this, "isFullscreen", {
      get: function () {
        return tmpIsFullscreen();
      },
    });

    /**
     * Gets or sets whether or not fullscreen functionality should be enabled.  This property is observable.
     *
     * @type {Boolean}
     * @see Fullscreen.enabled
     */
    this.isFullscreenEnabled = undefined;
    knockout.defineProperty(this, "isFullscreenEnabled", {
      get: function () {
        return tmpIsEnabled();
      },
      set: function (value) {
        tmpIsEnabled(value && Fullscreen.enabled);
      },
    });

    /**
     * Gets the tooltip.  This property is observable.
     *
     * @type {String}
     */
    this.tooltip = undefined;
    knockout.defineProperty(this, "tooltip", function () {
      if (!this.isFullscreenEnabled) {
        return "Full screen unavailable";
      }
      return tmpIsFullscreen() ? "Exit full screen" : "Full screen";
    });

    this._command = createCommand$2(function () {
      if (Fullscreen.fullscreen) {
        Fullscreen.exitFullscreen();
      } else {
        Fullscreen.requestFullscreen(that._fullscreenElement);
      }
    }, knockout.getObservable(this, "isFullscreenEnabled"));

    this._fullscreenElement = defaultValue(
      getElement(fullscreenElement),
      ownerDocument.body
    );

    this._callback = function () {
      tmpIsFullscreen(Fullscreen.fullscreen);
    };
    ownerDocument.addEventListener(Fullscreen.changeEventName, this._callback);
  }

  Object.defineProperties(FullscreenButtonViewModel.prototype, {
    /**
     * Gets or sets the HTML element to place into fullscreen mode when the
     * corresponding button is pressed.
     * @memberof FullscreenButtonViewModel.prototype
     *
     * @type {Element}
     */
    fullscreenElement: {
      //TODO:@exception {DeveloperError} value must be a valid HTML Element.
      get: function () {
        return this._fullscreenElement;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!(value instanceof Element)) {
          throw new DeveloperError("value must be a valid Element.");
        }
        //>>includeEnd('debug');

        this._fullscreenElement = value;
      },
    },

    /**
     * Gets the Command to toggle fullscreen mode.
     * @memberof FullscreenButtonViewModel.prototype
     *
     * @type {Command}
     */
    command: {
      get: function () {
        return this._command;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  FullscreenButtonViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the view model.  Should be called to
   * properly clean up the view model when it is no longer needed.
   */
  FullscreenButtonViewModel.prototype.destroy = function () {
    document.removeEventListener(Fullscreen.changeEventName, this._callback);
    destroyObject(this);
  };

  var enterFullScreenPath =
    "M 83.96875 17.5625 L 83.96875 17.59375 L 76.65625 24.875 L 97.09375 24.96875 L 76.09375 45.96875 L 81.9375 51.8125 L 102.78125 30.9375 L 102.875 51.15625 L 110.15625 43.875 L 110.1875 17.59375 L 83.96875 17.5625 z M 44.125 17.59375 L 17.90625 17.625 L 17.9375 43.90625 L 25.21875 51.1875 L 25.3125 30.96875 L 46.15625 51.8125 L 52 45.96875 L 31 25 L 51.4375 24.90625 L 44.125 17.59375 z M 46.0625 76.03125 L 25.1875 96.875 L 25.09375 76.65625 L 17.8125 83.9375 L 17.8125 110.21875 L 44 110.25 L 51.3125 102.9375 L 30.90625 102.84375 L 51.875 81.875 L 46.0625 76.03125 z M 82 76.15625 L 76.15625 82 L 97.15625 103 L 76.71875 103.0625 L 84.03125 110.375 L 110.25 110.34375 L 110.21875 84.0625 L 102.9375 76.8125 L 102.84375 97 L 82 76.15625 z";
  var exitFullScreenPath =
    "M 104.34375 17.5625 L 83.5 38.4375 L 83.40625 18.21875 L 76.125 25.5 L 76.09375 51.78125 L 102.3125 51.8125 L 102.3125 51.78125 L 109.625 44.5 L 89.1875 44.40625 L 110.1875 23.40625 L 104.34375 17.5625 z M 23.75 17.59375 L 17.90625 23.4375 L 38.90625 44.4375 L 18.5 44.53125 L 25.78125 51.8125 L 52 51.78125 L 51.96875 25.53125 L 44.6875 18.25 L 44.625 38.46875 L 23.75 17.59375 z M 25.6875 76.03125 L 18.375 83.3125 L 38.78125 83.40625 L 17.8125 104.40625 L 23.625 110.25 L 44.5 89.375 L 44.59375 109.59375 L 51.875 102.3125 L 51.875 76.0625 L 25.6875 76.03125 z M 102.375 76.15625 L 76.15625 76.1875 L 76.1875 102.4375 L 83.46875 109.71875 L 83.5625 89.53125 L 104.40625 110.375 L 110.25 104.53125 L 89.25 83.53125 L 109.6875 83.46875 L 102.375 76.15625 z";

  /**
   * A single button widget for toggling fullscreen mode.
   *
   * @alias FullscreenButton
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Element|String} [fullscreenElement=document.body] The element or id to be placed into fullscreen mode.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   * @see Fullscreen
   */
  function FullscreenButton(container, fullscreenElement) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var viewModel = new FullscreenButtonViewModel(fullscreenElement, container);

    viewModel._exitFullScreenPath = exitFullScreenPath;
    viewModel._enterFullScreenPath = enterFullScreenPath;

    var element = document.createElement("button");
    element.type = "button";
    element.className = "cesium-button cesium-fullscreenButton";
    element.setAttribute(
      "data-bind",
      "\
attr: { title: tooltip },\
click: command,\
enable: isFullscreenEnabled,\
cesiumSvgPath: { path: isFullscreen ? _exitFullScreenPath : _enterFullScreenPath, width: 128, height: 128 }"
    );

    container.appendChild(element);

    knockout.applyBindings(viewModel, element);

    this._container = container;
    this._viewModel = viewModel;
    this._element = element;
  }

  Object.defineProperties(FullscreenButton.prototype, {
    /**
     * Gets the parent container.
     * @memberof FullscreenButton.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof FullscreenButton.prototype
     *
     * @type {FullscreenButtonViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  FullscreenButton.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  FullscreenButton.prototype.destroy = function () {
    this._viewModel.destroy();

    knockout.cleanNode(this._element);
    this._container.removeChild(this._element);

    return destroyObject(this);
  };

  // The height we use if geocoding to a specific point instead of an rectangle.
  var DEFAULT_HEIGHT = 1000;

  /**
   * The view model for the {@link Geocoder} widget.
   * @alias GeocoderViewModel
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Scene} options.scene The Scene instance to use.
   * @param {GeocoderService[]} [options.geocoderServices] Geocoder services to use for geocoding queries.
   *        If more than one are supplied, suggestions will be gathered for the geocoders that support it,
   *        and if no suggestion is selected the result from the first geocoder service wil be used.
   * @param {Number} [options.flightDuration] The duration of the camera flight to an entered location, in seconds.
   * @param {Geocoder.DestinationFoundFunction} [options.destinationFound=GeocoderViewModel.flyToDestination] A callback function that is called after a successful geocode.  If not supplied, the default behavior is to fly the camera to the result destination.
   */
  function GeocoderViewModel(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.scene)) {
      throw new DeveloperError("options.scene is required.");
    }
    //>>includeEnd('debug');

    if (defined(options.geocoderServices)) {
      this._geocoderServices = options.geocoderServices;
    } else {
      this._geocoderServices = [
        new CartographicGeocoderService(),
        new IonGeocoderService({ scene: options.scene }),
      ];
    }

    this._viewContainer = options.container;
    this._scene = options.scene;
    this._flightDuration = options.flightDuration;
    this._searchText = "";
    this._isSearchInProgress = false;
    this._geocodePromise = undefined;
    this._complete = new Event();
    this._suggestions = [];
    this._selectedSuggestion = undefined;
    this._showSuggestions = true;

    this._handleArrowDown = handleArrowDown;
    this._handleArrowUp = handleArrowUp;

    var that = this;

    this._suggestionsVisible = knockout.pureComputed(function () {
      var suggestions = knockout.getObservable(that, "_suggestions");
      var suggestionsNotEmpty = suggestions().length > 0;
      var showSuggestions = knockout.getObservable(that, "_showSuggestions")();
      return suggestionsNotEmpty && showSuggestions;
    });

    this._searchCommand = createCommand$2(function (geocodeType) {
      geocodeType = defaultValue(geocodeType, GeocodeType$1.SEARCH);
      that._focusTextbox = false;
      if (defined(that._selectedSuggestion)) {
        that.activateSuggestion(that._selectedSuggestion);
        return false;
      }
      that.hideSuggestions();
      if (that.isSearchInProgress) {
        cancelGeocode(that);
      } else {
        geocode(that, that._geocoderServices, geocodeType);
      }
    });

    this.deselectSuggestion = function () {
      that._selectedSuggestion = undefined;
    };

    this.handleKeyDown = function (data, event) {
      var downKey =
        event.key === "ArrowDown" || event.key === "Down" || event.keyCode === 40;
      var upKey =
        event.key === "ArrowUp" || event.key === "Up" || event.keyCode === 38;
      if (downKey || upKey) {
        event.preventDefault();
      }

      return true;
    };

    this.handleKeyUp = function (data, event) {
      var downKey =
        event.key === "ArrowDown" || event.key === "Down" || event.keyCode === 40;
      var upKey =
        event.key === "ArrowUp" || event.key === "Up" || event.keyCode === 38;
      var enterKey = event.key === "Enter" || event.keyCode === 13;
      if (upKey) {
        handleArrowUp(that);
      } else if (downKey) {
        handleArrowDown(that);
      } else if (enterKey) {
        that._searchCommand();
      }
      return true;
    };

    this.activateSuggestion = function (data) {
      that.hideSuggestions();
      that._searchText = data.displayName;
      var destination = data.destination;
      clearSuggestions(that);
      that.destinationFound(that, destination);
    };

    this.hideSuggestions = function () {
      that._showSuggestions = false;
      that._selectedSuggestion = undefined;
    };

    this.showSuggestions = function () {
      that._showSuggestions = true;
    };

    this.handleMouseover = function (data, event) {
      if (data !== that._selectedSuggestion) {
        that._selectedSuggestion = data;
      }
    };

    /**
     * Gets or sets a value indicating if this instance should always show its text input field.
     *
     * @type {Boolean}
     * @default false
     */
    this.keepExpanded = false;

    /**
     * True if the geocoder should query as the user types to autocomplete
     * @type {Boolean}
     * @default true
     */
    this.autoComplete = defaultValue(options.autocomplete, true);

    /**
     * Gets and sets the command called when a geocode destination is found
     * @type {Geocoder.DestinationFoundFunction}
     */
    this.destinationFound = defaultValue(
      options.destinationFound,
      GeocoderViewModel.flyToDestination
    );

    this._focusTextbox = false;

    knockout.track(this, [
      "_searchText",
      "_isSearchInProgress",
      "keepExpanded",
      "_suggestions",
      "_selectedSuggestion",
      "_showSuggestions",
      "_focusTextbox",
    ]);

    var searchTextObservable = knockout.getObservable(this, "_searchText");
    searchTextObservable.extend({ rateLimit: { timeout: 500 } });
    this._suggestionSubscription = searchTextObservable.subscribe(function () {
      GeocoderViewModel._updateSearchSuggestions(that);
    });
    /**
     * Gets a value indicating whether a search is currently in progress.  This property is observable.
     *
     * @type {Boolean}
     */
    this.isSearchInProgress = undefined;
    knockout.defineProperty(this, "isSearchInProgress", {
      get: function () {
        return this._isSearchInProgress;
      },
    });

    /**
     * Gets or sets the text to search for.  The text can be an address, or longitude, latitude,
     * and optional height, where longitude and latitude are in degrees and height is in meters.
     *
     * @type {String}
     */
    this.searchText = undefined;
    knockout.defineProperty(this, "searchText", {
      get: function () {
        if (this.isSearchInProgress) {
          return "Searching...";
        }

        return this._searchText;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (typeof value !== "string") {
          throw new DeveloperError("value must be a valid string.");
        }
        //>>includeEnd('debug');
        this._searchText = value;
      },
    });

    /**
     * Gets or sets the the duration of the camera flight in seconds.
     * A value of zero causes the camera to instantly switch to the geocoding location.
     * The duration will be computed based on the distance when undefined.
     *
     * @type {Number|undefined}
     * @default undefined
     */
    this.flightDuration = undefined;
    knockout.defineProperty(this, "flightDuration", {
      get: function () {
        return this._flightDuration;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value < 0) {
          throw new DeveloperError("value must be positive.");
        }
        //>>includeEnd('debug');

        this._flightDuration = value;
      },
    });
  }

  Object.defineProperties(GeocoderViewModel.prototype, {
    /**
     * Gets the event triggered on flight completion.
     * @memberof GeocoderViewModel.prototype
     *
     * @type {Event}
     */
    complete: {
      get: function () {
        return this._complete;
      },
    },

    /**
     * Gets the scene to control.
     * @memberof GeocoderViewModel.prototype
     *
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets the Command that is executed when the button is clicked.
     * @memberof GeocoderViewModel.prototype
     *
     * @type {Command}
     */
    search: {
      get: function () {
        return this._searchCommand;
      },
    },

    /**
     * Gets the currently selected geocoder search suggestion
     * @memberof GeocoderViewModel.prototype
     *
     * @type {Object}
     */
    selectedSuggestion: {
      get: function () {
        return this._selectedSuggestion;
      },
    },

    /**
     * Gets the list of geocoder search suggestions
     * @memberof GeocoderViewModel.prototype
     *
     * @type {Object[]}
     */
    suggestions: {
      get: function () {
        return this._suggestions;
      },
    },
  });

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  GeocoderViewModel.prototype.destroy = function () {
    this._suggestionSubscription.dispose();
  };

  function handleArrowUp(viewModel) {
    if (viewModel._suggestions.length === 0) {
      return;
    }
    var next;
    var currentIndex = viewModel._suggestions.indexOf(
      viewModel._selectedSuggestion
    );
    if (currentIndex === -1 || currentIndex === 0) {
      viewModel._selectedSuggestion = undefined;
      return;
    }
    next = currentIndex - 1;
    viewModel._selectedSuggestion = viewModel._suggestions[next];
    GeocoderViewModel._adjustSuggestionsScroll(viewModel, next);
  }

  function handleArrowDown(viewModel) {
    if (viewModel._suggestions.length === 0) {
      return;
    }
    var numberOfSuggestions = viewModel._suggestions.length;
    var currentIndex = viewModel._suggestions.indexOf(
      viewModel._selectedSuggestion
    );
    var next = (currentIndex + 1) % numberOfSuggestions;
    viewModel._selectedSuggestion = viewModel._suggestions[next];

    GeocoderViewModel._adjustSuggestionsScroll(viewModel, next);
  }

  function computeFlyToLocationForCartographic(cartographic, terrainProvider) {
    var availability = defined(terrainProvider)
      ? terrainProvider.availability
      : undefined;

    if (!defined(availability)) {
      cartographic.height += DEFAULT_HEIGHT;
      return when.resolve(cartographic);
    }

    return sampleTerrainMostDetailed(terrainProvider, [cartographic]).then(
      function (positionOnTerrain) {
        cartographic = positionOnTerrain[0];
        cartographic.height += DEFAULT_HEIGHT;
        return cartographic;
      }
    );
  }

  function flyToDestination(viewModel, destination) {
    var scene = viewModel._scene;
    var mapProjection = scene.mapProjection;
    var ellipsoid = mapProjection.ellipsoid;

    var camera = scene.camera;
    var terrainProvider = scene.terrainProvider;
    var finalDestination = destination;

    var promise;
    if (destination instanceof Rectangle) {
      // Some geocoders return a Rectangle of zero width/height, treat it like a point instead.
      if (
        CesiumMath.equalsEpsilon(
          destination.south,
          destination.north,
          CesiumMath.EPSILON7
        ) &&
        CesiumMath.equalsEpsilon(
          destination.east,
          destination.west,
          CesiumMath.EPSILON7
        )
      ) {
        // destination is now a Cartographic
        destination = Rectangle.center(destination);
      } else {
        promise = computeFlyToLocationForRectangle(destination, scene);
      }
    } else {
      // destination is a Cartesian3
      destination = ellipsoid.cartesianToCartographic(destination);
    }

    if (!defined(promise)) {
      promise = computeFlyToLocationForCartographic(destination, terrainProvider);
    }

    promise
      .then(function (result) {
        finalDestination = ellipsoid.cartographicToCartesian(result);
      })
      .always(function () {
        // Whether terrain querying succeeded or not, fly to the destination.
        camera.flyTo({
          destination: finalDestination,
          complete: function () {
            viewModel._complete.raiseEvent();
          },
          duration: viewModel._flightDuration,
          endTransform: Matrix4.IDENTITY,
        });
      });
  }

  function chainPromise(promise, geocoderService, query, geocodeType) {
    return promise.then(function (result) {
      if (
        defined(result) &&
        result.state === "fulfilled" &&
        result.value.length > 0
      ) {
        return result;
      }
      var nextPromise = geocoderService
        .geocode(query, geocodeType)
        .then(function (result) {
          return { state: "fulfilled", value: result };
        })
        .otherwise(function (err) {
          return { state: "rejected", reason: err };
        });

      return nextPromise;
    });
  }

  function geocode(viewModel, geocoderServices, geocodeType) {
    var query = viewModel._searchText;

    if (hasOnlyWhitespace(query)) {
      viewModel.showSuggestions();
      return;
    }

    viewModel._isSearchInProgress = true;

    var promise = when.resolve();
    for (var i = 0; i < geocoderServices.length; i++) {
      promise = chainPromise(promise, geocoderServices[i], query, geocodeType);
    }

    viewModel._geocodePromise = promise;
    promise.then(function (result) {
      if (promise.cancel) {
        return;
      }
      viewModel._isSearchInProgress = false;

      var geocoderResults = result.value;
      if (
        result.state === "fulfilled" &&
        defined(geocoderResults) &&
        geocoderResults.length > 0
      ) {
        viewModel._searchText = geocoderResults[0].displayName;
        viewModel.destinationFound(viewModel, geocoderResults[0].destination);
        return;
      }
      viewModel._searchText = query + " (not found)";
    });
  }

  function adjustSuggestionsScroll(viewModel, focusedItemIndex) {
    var container = getElement(viewModel._viewContainer);
    var searchResults = container.getElementsByClassName("search-results")[0];
    var listItems = container.getElementsByTagName("li");
    var element = listItems[focusedItemIndex];

    if (focusedItemIndex === 0) {
      searchResults.scrollTop = 0;
      return;
    }

    var offsetTop = element.offsetTop;
    if (offsetTop + element.clientHeight > searchResults.clientHeight) {
      searchResults.scrollTop = offsetTop + element.clientHeight;
    } else if (offsetTop < searchResults.scrollTop) {
      searchResults.scrollTop = offsetTop;
    }
  }

  function cancelGeocode(viewModel) {
    viewModel._isSearchInProgress = false;
    if (defined(viewModel._geocodePromise)) {
      viewModel._geocodePromise.cancel = true;
      viewModel._geocodePromise = undefined;
    }
  }

  function hasOnlyWhitespace(string) {
    return /^\s*$/.test(string);
  }

  function clearSuggestions(viewModel) {
    knockout.getObservable(viewModel, "_suggestions").removeAll();
  }

  function updateSearchSuggestions(viewModel) {
    if (!viewModel.autoComplete) {
      return;
    }

    var query = viewModel._searchText;

    clearSuggestions(viewModel);
    if (hasOnlyWhitespace(query)) {
      return;
    }

    var promise = when.resolve([]);
    viewModel._geocoderServices.forEach(function (service) {
      promise = promise.then(function (results) {
        if (results.length >= 5) {
          return results;
        }
        return service
          .geocode(query, GeocodeType$1.AUTOCOMPLETE)
          .then(function (newResults) {
            results = results.concat(newResults);
            return results;
          });
      });
    });
    promise.then(function (results) {
      var suggestions = viewModel._suggestions;
      for (var i = 0; i < results.length; i++) {
        suggestions.push(results[i]);
      }
    });
  }

  /**
   * A function to fly to the destination found by a successful geocode.
   * @type {Geocoder.DestinationFoundFunction}
   */
  GeocoderViewModel.flyToDestination = flyToDestination;

  //exposed for testing
  GeocoderViewModel._updateSearchSuggestions = updateSearchSuggestions;
  GeocoderViewModel._adjustSuggestionsScroll = adjustSuggestionsScroll;

  var startSearchPath =
    "M29.772,26.433l-7.126-7.126c0.96-1.583,1.523-3.435,1.524-5.421C24.169,8.093,19.478,3.401,13.688,3.399C7.897,3.401,3.204,8.093,3.204,13.885c0,5.789,4.693,10.481,10.484,10.481c1.987,0,3.839-0.563,5.422-1.523l7.128,7.127L29.772,26.433zM7.203,13.885c0.006-3.582,2.903-6.478,6.484-6.486c3.579,0.008,6.478,2.904,6.484,6.486c-0.007,3.58-2.905,6.476-6.484,6.484C10.106,20.361,7.209,17.465,7.203,13.885z";
  var stopSearchPath =
    "M24.778,21.419 19.276,15.917 24.777,10.415 21.949,7.585 16.447,13.087 10.945,7.585 8.117,10.415 13.618,15.917 8.116,21.419 10.946,24.248 16.447,18.746 21.948,24.248z";

  /**
   * A widget for finding addresses and landmarks, and flying the camera to them.  Geocoding is
   * performed using {@link https://cesium.com/cesium-ion/|Cesium ion}.
   *
   * @alias Geocoder
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Element|String} options.container The DOM element or ID that will contain the widget.
   * @param {Scene} options.scene The Scene instance to use.
   * @param {GeocoderService[]} [options.geocoderServices] The geocoder services to be used
   * @param {Boolean} [options.autoComplete = true] True if the geocoder should query as the user types to autocomplete
   * @param {Number} [options.flightDuration=1.5] The duration of the camera flight to an entered location, in seconds.
   * @param {Geocoder.DestinationFoundFunction} [options.destinationFound=GeocoderViewModel.flyToDestination] A callback function that is called after a successful geocode.  If not supplied, the default behavior is to fly the camera to the result destination.
   */
  function Geocoder(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.container)) {
      throw new DeveloperError("options.container is required.");
    }
    if (!defined(options.scene)) {
      throw new DeveloperError("options.scene is required.");
    }
    //>>includeEnd('debug');

    var container = getElement(options.container);
    var viewModel = new GeocoderViewModel(options);

    viewModel._startSearchPath = startSearchPath;
    viewModel._stopSearchPath = stopSearchPath;

    var form = document.createElement("form");
    form.setAttribute("data-bind", "submit: search");

    var textBox = document.createElement("input");
    textBox.type = "search";
    textBox.className = "cesium-geocoder-input";
    textBox.setAttribute("placeholder", "Enter an address or landmark...");
    textBox.setAttribute(
      "data-bind",
      '\
textInput: searchText,\
disable: isSearchInProgress,\
event: { keyup: handleKeyUp, keydown: handleKeyDown, mouseover: deselectSuggestion },\
css: { "cesium-geocoder-input-wide" : keepExpanded || searchText.length > 0 },\
hasFocus: _focusTextbox'
    );

    this._onTextBoxFocus = function () {
      // as of 2016-10-19, setTimeout is required to ensure that the
      // text is focused on Safari 10
      setTimeout(function () {
        textBox.select();
      }, 0);
    };

    textBox.addEventListener("focus", this._onTextBoxFocus, false);
    form.appendChild(textBox);
    this._textBox = textBox;

    var searchButton = document.createElement("span");
    searchButton.className = "cesium-geocoder-searchButton";
    searchButton.setAttribute(
      "data-bind",
      "\
click: search,\
cesiumSvgPath: { path: isSearchInProgress ? _stopSearchPath : _startSearchPath, width: 32, height: 32 }"
    );
    form.appendChild(searchButton);

    container.appendChild(form);

    var searchSuggestionsContainer = document.createElement("div");
    searchSuggestionsContainer.className = "search-results";
    searchSuggestionsContainer.setAttribute(
      "data-bind",
      "visible: _suggestionsVisible"
    );

    var suggestionsList = document.createElement("ul");
    suggestionsList.setAttribute("data-bind", "foreach: _suggestions");
    var suggestions = document.createElement("li");
    suggestionsList.appendChild(suggestions);
    suggestions.setAttribute(
      "data-bind",
      "text: $data.displayName, \
click: $parent.activateSuggestion, \
event: { mouseover: $parent.handleMouseover}, \
css: { active: $data === $parent._selectedSuggestion }"
    );

    searchSuggestionsContainer.appendChild(suggestionsList);
    container.appendChild(searchSuggestionsContainer);

    knockout.applyBindings(viewModel, form);
    knockout.applyBindings(viewModel, searchSuggestionsContainer);

    this._container = container;
    this._searchSuggestionsContainer = searchSuggestionsContainer;
    this._viewModel = viewModel;
    this._form = form;

    this._onInputBegin = function (e) {
      // e.target will not be correct if we are inside of the Shadow DOM
      // and contains will always fail. To retrieve the correct target,
      // we need to access the first element of the composedPath.
      // This allows us to use shadow DOM if it exists and fall
      // back to legacy behavior if its not being used.

      var target = e.target;
      if (typeof e.composedPath === "function") {
        target = e.composedPath()[0];
      }

      if (!container.contains(target)) {
        viewModel._focusTextbox = false;
        viewModel.hideSuggestions();
      }
    };

    this._onInputEnd = function (e) {
      viewModel._focusTextbox = true;
      viewModel.showSuggestions();
    };

    //We subscribe to both begin and end events in order to give the text box
    //focus no matter where on the widget is clicked.

    if (FeatureDetection.supportsPointerEvents()) {
      document.addEventListener("pointerdown", this._onInputBegin, true);
      container.addEventListener("pointerup", this._onInputEnd, true);
      container.addEventListener("pointercancel", this._onInputEnd, true);
    } else {
      document.addEventListener("mousedown", this._onInputBegin, true);
      container.addEventListener("mouseup", this._onInputEnd, true);
      document.addEventListener("touchstart", this._onInputBegin, true);
      container.addEventListener("touchend", this._onInputEnd, true);
      container.addEventListener("touchcancel", this._onInputEnd, true);
    }
  }

  Object.defineProperties(Geocoder.prototype, {
    /**
     * Gets the parent container.
     * @memberof Geocoder.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the parent container.
     * @memberof Geocoder.prototype
     *
     * @type {Element}
     */
    searchSuggestionsContainer: {
      get: function () {
        return this._searchSuggestionsContainer;
      },
    },

    /**
     * Gets the view model.
     * @memberof Geocoder.prototype
     *
     * @type {GeocoderViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  Geocoder.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  Geocoder.prototype.destroy = function () {
    var container = this._container;
    if (FeatureDetection.supportsPointerEvents()) {
      document.removeEventListener("pointerdown", this._onInputBegin, true);
      container.removeEventListener("pointerup", this._onInputEnd, true);
    } else {
      document.removeEventListener("mousedown", this._onInputBegin, true);
      container.removeEventListener("mouseup", this._onInputEnd, true);
      document.removeEventListener("touchstart", this._onInputBegin, true);
      container.removeEventListener("touchend", this._onInputEnd, true);
    }
    this._viewModel.destroy();
    knockout.cleanNode(this._form);
    knockout.cleanNode(this._searchSuggestionsContainer);
    container.removeChild(this._form);
    container.removeChild(this._searchSuggestionsContainer);
    this._textBox.removeEventListener("focus", this._onTextBoxFocus, false);

    return destroyObject(this);
  };

  /**
   * The view model for {@link HomeButton}.
   * @alias HomeButtonViewModel
   * @constructor
   *
   * @param {Scene} scene The scene instance to use.
   * @param {Number} [duration] The duration of the camera flight in seconds.
   */
  function HomeButtonViewModel(scene, duration) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    this._scene = scene;
    this._duration = duration;

    var that = this;
    this._command = createCommand$2(function () {
      that._scene.camera.flyHome(that._duration);
    });

    /**
     * Gets or sets the tooltip.  This property is observable.
     *
     * @type {String}
     */
    this.tooltip = "View Home";

    knockout.track(this, ["tooltip"]);
  }

  Object.defineProperties(HomeButtonViewModel.prototype, {
    /**
     * Gets the scene to control.
     * @memberof HomeButtonViewModel.prototype
     *
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets the Command that is executed when the button is clicked.
     * @memberof HomeButtonViewModel.prototype
     *
     * @type {Command}
     */
    command: {
      get: function () {
        return this._command;
      },
    },

    /**
     * Gets or sets the the duration of the camera flight in seconds.
     * A value of zero causes the camera to instantly switch to home view.
     * The duration will be computed based on the distance when undefined.
     * @memberof HomeButtonViewModel.prototype
     *
     * @type {Number|undefined}
     */
    duration: {
      get: function () {
        return this._duration;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (defined(value) && value < 0) {
          throw new DeveloperError("value must be positive.");
        }
        //>>includeEnd('debug');

        this._duration = value;
      },
    },
  });

  /**
   * A single button widget for returning to the default camera view of the current scene.
   *
   * @alias HomeButton
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene The Scene instance to use.
   * @param {Number} [duration] The time, in seconds, it takes to complete the camera flight home.
   */
  function HomeButton(container, scene, duration) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var viewModel = new HomeButtonViewModel(scene, duration);

    viewModel._svgPath =
      "M14,4l-10,8.75h20l-4.25-3.7188v-4.6562h-2.812v2.1875l-2.938-2.5625zm-7.0938,9.906v10.094h14.094v-10.094h-14.094zm2.1876,2.313h3.3122v4.25h-3.3122v-4.25zm5.8442,1.281h3.406v6.438h-3.406v-6.438z";

    var element = document.createElement("button");
    element.type = "button";
    element.className = "cesium-button cesium-toolbar-button cesium-home-button";
    element.setAttribute(
      "data-bind",
      "\
attr: { title: tooltip },\
click: command,\
cesiumSvgPath: { path: _svgPath, width: 28, height: 28 }"
    );

    container.appendChild(element);

    knockout.applyBindings(viewModel, element);

    this._container = container;
    this._viewModel = viewModel;
    this._element = element;
  }

  Object.defineProperties(HomeButton.prototype, {
    /**
     * Gets the parent container.
     * @memberof HomeButton.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof HomeButton.prototype
     *
     * @type {HomeButtonViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  HomeButton.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  HomeButton.prototype.destroy = function () {
    knockout.cleanNode(this._element);
    this._container.removeChild(this._element);

    return destroyObject(this);
  };

  var cameraEnabledPath =
    "M 13.84375 7.03125 C 11.412798 7.03125 9.46875 8.975298 9.46875 11.40625 L 9.46875 11.59375 L 2.53125 7.21875 L 2.53125 24.0625 L 9.46875 19.6875 C 9.4853444 22.104033 11.423165 24.0625 13.84375 24.0625 L 25.875 24.0625 C 28.305952 24.0625 30.28125 22.087202 30.28125 19.65625 L 30.28125 11.40625 C 30.28125 8.975298 28.305952 7.03125 25.875 7.03125 L 13.84375 7.03125 z";
  var cameraDisabledPath =
    "M 27.34375 1.65625 L 5.28125 27.9375 L 8.09375 30.3125 L 30.15625 4.03125 L 27.34375 1.65625 z M 13.84375 7.03125 C 11.412798 7.03125 9.46875 8.975298 9.46875 11.40625 L 9.46875 11.59375 L 2.53125 7.21875 L 2.53125 24.0625 L 9.46875 19.6875 C 9.4724893 20.232036 9.5676108 20.7379 9.75 21.21875 L 21.65625 7.03125 L 13.84375 7.03125 z M 28.21875 7.71875 L 14.53125 24.0625 L 25.875 24.0625 C 28.305952 24.0625 30.28125 22.087202 30.28125 19.65625 L 30.28125 11.40625 C 30.28125 9.8371439 29.456025 8.4902779 28.21875 7.71875 z";

  /**
   * The view model for {@link InfoBox}.
   * @alias InfoBoxViewModel
   * @constructor
   */
  function InfoBoxViewModel() {
    this._cameraClicked = new Event();
    this._closeClicked = new Event();

    /**
     * Gets or sets the maximum height of the info box in pixels.  This property is observable.
     * @type {Number}
     */
    this.maxHeight = 500;

    /**
     * Gets or sets whether the camera tracking icon is enabled.
     * @type {Boolean}
     */
    this.enableCamera = false;

    /**
     * Gets or sets the status of current camera tracking of the selected object.
     * @type {Boolean}
     */
    this.isCameraTracking = false;

    /**
     * Gets or sets the visibility of the info box.
     * @type {Boolean}
     */
    this.showInfo = false;

    /**
     * Gets or sets the title text in the info box.
     * @type {String}
     */
    this.titleText = "";

    /**
     * Gets or sets the description HTML for the info box.
     * @type {String}
     */
    this.description = "";

    knockout.track(this, [
      "showInfo",
      "titleText",
      "description",
      "maxHeight",
      "enableCamera",
      "isCameraTracking",
    ]);

    this._loadingIndicatorHtml =
      '<div class="cesium-infoBox-loadingContainer"><span class="cesium-infoBox-loading"></span></div>';

    /**
     * Gets the SVG path of the camera icon, which can change to be "crossed out" or not.
     * @type {String}
     */
    this.cameraIconPath = undefined;
    knockout.defineProperty(this, "cameraIconPath", {
      get: function () {
        return !this.enableCamera || this.isCameraTracking
          ? cameraDisabledPath
          : cameraEnabledPath;
      },
    });

    knockout.defineProperty(this, "_bodyless", {
      get: function () {
        return !defined(this.description) || this.description.length === 0;
      },
    });
  }

  /**
   * Gets the maximum height of sections within the info box, minus an offset, in CSS-ready form.
   * @param {Number} offset The offset in pixels.
   * @returns {String}
   */
  InfoBoxViewModel.prototype.maxHeightOffset = function (offset) {
    return this.maxHeight - offset + "px";
  };

  Object.defineProperties(InfoBoxViewModel.prototype, {
    /**
     * Gets an {@link Event} that is fired when the user clicks the camera icon.
     * @memberof InfoBoxViewModel.prototype
     * @type {Event}
     */
    cameraClicked: {
      get: function () {
        return this._cameraClicked;
      },
    },
    /**
     * Gets an {@link Event} that is fired when the user closes the info box.
     * @memberof InfoBoxViewModel.prototype
     * @type {Event}
     */
    closeClicked: {
      get: function () {
        return this._closeClicked;
      },
    },
  });

  /**
   * A widget for displaying information or a description.
   *
   * @alias InfoBox
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   */
  function InfoBox(container) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("container", container);
    //>>includeEnd('debug')

    container = getElement(container);

    var infoElement = document.createElement("div");
    infoElement.className = "cesium-infoBox";
    infoElement.setAttribute(
      "data-bind",
      '\
css: { "cesium-infoBox-visible" : showInfo, "cesium-infoBox-bodyless" : _bodyless }'
    );
    container.appendChild(infoElement);

    var titleElement = document.createElement("div");
    titleElement.className = "cesium-infoBox-title";
    titleElement.setAttribute("data-bind", "text: titleText");
    infoElement.appendChild(titleElement);

    var cameraElement = document.createElement("button");
    cameraElement.type = "button";
    cameraElement.className = "cesium-button cesium-infoBox-camera";
    cameraElement.setAttribute(
      "data-bind",
      '\
attr: { title: "Focus camera on object" },\
click: function () { cameraClicked.raiseEvent(this); },\
enable: enableCamera,\
cesiumSvgPath: { path: cameraIconPath, width: 32, height: 32 }'
    );
    infoElement.appendChild(cameraElement);

    var closeElement = document.createElement("button");
    closeElement.type = "button";
    closeElement.className = "cesium-infoBox-close";
    closeElement.setAttribute(
      "data-bind",
      "\
click: function () { closeClicked.raiseEvent(this); }"
    );
    closeElement.innerHTML = "&times;";
    infoElement.appendChild(closeElement);

    var frame = document.createElement("iframe");
    frame.className = "cesium-infoBox-iframe";
    frame.setAttribute("sandbox", "allow-same-origin allow-popups allow-forms"); //allow-pointer-lock allow-scripts allow-top-navigation
    frame.setAttribute(
      "data-bind",
      "style : { maxHeight : maxHeightOffset(40) }"
    );
    frame.setAttribute("allowfullscreen", true);
    infoElement.appendChild(frame);

    var viewModel = new InfoBoxViewModel();
    knockout.applyBindings(viewModel, infoElement);

    this._container = container;
    this._element = infoElement;
    this._frame = frame;
    this._viewModel = viewModel;
    this._descriptionSubscription = undefined;

    var that = this;
    //We can't actually add anything into the frame until the load event is fired
    frame.addEventListener("load", function () {
      var frameDocument = frame.contentDocument;

      //We inject default css into the content iframe,
      //end users can remove it or add their own via the exposed frame property.
      var cssLink = frameDocument.createElement("link");
      cssLink.href = buildModuleUrl("Widgets/InfoBox/InfoBoxDescription.css");
      cssLink.rel = "stylesheet";
      cssLink.type = "text/css";

      //div to use for description content.
      var frameContent = frameDocument.createElement("div");
      frameContent.className = "cesium-infoBox-description";

      frameDocument.head.appendChild(cssLink);
      frameDocument.body.appendChild(frameContent);

      //We manually subscribe to the description event rather than through a binding for two reasons.
      //1. It's an easy way to ensure order of operation so that we can adjust the height.
      //2. Knockout does not bind to elements inside of an iFrame, so we would have to apply a second binding
      //   model anyway.
      that._descriptionSubscription = subscribeAndEvaluate(
        viewModel,
        "description",
        function (value) {
          // Set the frame to small height, force vertical scroll bar to appear, and text to wrap accordingly.
          frame.style.height = "5px";
          frameContent.innerHTML = value;

          //If the snippet is a single element, then use its background
          //color for the body of the InfoBox. This makes the padding match
          //the content and produces much nicer results.
          var background = null;
          var firstElementChild = frameContent.firstElementChild;
          if (
            firstElementChild !== null &&
            frameContent.childNodes.length === 1
          ) {
            var style = window.getComputedStyle(firstElementChild);
            if (style !== null) {
              var backgroundColor = style["background-color"];
              var color = Color.fromCssColorString(backgroundColor);
              if (defined(color) && color.alpha !== 0) {
                background = style["background-color"];
              }
            }
          }
          infoElement.style["background-color"] = background;

          // Measure and set the new custom height, based on text wrapped above.
          var height = frameContent.getBoundingClientRect().height;
          frame.style.height = height + "px";
        }
      );
    });

    //Chrome does not send the load event unless we explicitly set a src
    frame.setAttribute("src", "about:blank");
  }

  Object.defineProperties(InfoBox.prototype, {
    /**
     * Gets the parent container.
     * @memberof InfoBox.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof InfoBox.prototype
     *
     * @type {InfoBoxViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },

    /**
     * Gets the iframe used to display the description.
     * @memberof InfoBox.prototype
     *
     * @type {HTMLIFrameElement}
     */
    frame: {
      get: function () {
        return this._frame;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  InfoBox.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  InfoBox.prototype.destroy = function () {
    var container = this._container;
    knockout.cleanNode(this._element);
    container.removeChild(this._element);

    if (defined(this._descriptionSubscription)) {
      this._descriptionSubscription.dispose();
    }

    return destroyObject(this);
  };

  /**
   * The view model for {@link NavigationHelpButton}.
   * @alias NavigationHelpButtonViewModel
   * @constructor
   */
  function NavigationHelpButtonViewModel() {
    /**
     * Gets or sets whether the instructions are currently shown.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.showInstructions = false;

    var that = this;
    this._command = createCommand$2(function () {
      that.showInstructions = !that.showInstructions;
    });
    this._showClick = createCommand$2(function () {
      that._touch = false;
    });
    this._showTouch = createCommand$2(function () {
      that._touch = true;
    });

    this._touch = false;

    /**
     * Gets or sets the tooltip.  This property is observable.
     *
     * @type {String}
     */
    this.tooltip = "Navigation Instructions";

    knockout.track(this, ["tooltip", "showInstructions", "_touch"]);
  }

  Object.defineProperties(NavigationHelpButtonViewModel.prototype, {
    /**
     * Gets the Command that is executed when the button is clicked.
     * @memberof NavigationHelpButtonViewModel.prototype
     *
     * @type {Command}
     */
    command: {
      get: function () {
        return this._command;
      },
    },

    /**
     * Gets the Command that is executed when the mouse instructions should be shown.
     * @memberof NavigationHelpButtonViewModel.prototype
     *
     * @type {Command}
     */
    showClick: {
      get: function () {
        return this._showClick;
      },
    },

    /**
     * Gets the Command that is executed when the touch instructions should be shown.
     * @memberof NavigationHelpButtonViewModel.prototype
     *
     * @type {Command}
     */
    showTouch: {
      get: function () {
        return this._showTouch;
      },
    },
  });

  /**
   * <p>The NavigationHelpButton is a single button widget for displaying instructions for
   * navigating the globe with the mouse.</p><p style="clear: both;"></p><br/>
   *
   * @alias NavigationHelpButton
   * @constructor
   *
   * @param {Object} options Object with the following properties:
   * @param {Element|String} options.container The DOM element or ID that will contain the widget.
   * @param {Boolean} [options.instructionsInitiallyVisible=false] True if the navigation instructions should initially be visible; otherwise, false.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   * @example
   * // In HTML head, include a link to the NavigationHelpButton.css stylesheet,
   * // and in the body, include: <div id="navigationHelpButtonContainer"></div>
   *
   * var navigationHelpButton = new Cesium.NavigationHelpButton({
   *     container : 'navigationHelpButtonContainer'
   * });
   */
  function NavigationHelpButton(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.container)) {
      throw new DeveloperError("options.container is required.");
    }
    //>>includeEnd('debug');

    var container = getElement(options.container);

    var viewModel = new NavigationHelpButtonViewModel();

    var showInsructionsDefault = defaultValue(
      options.instructionsInitiallyVisible,
      false
    );
    viewModel.showInstructions = showInsructionsDefault;

    viewModel._svgPath =
      "M16,1.466C7.973,1.466,1.466,7.973,1.466,16c0,8.027,6.507,14.534,14.534,14.534c8.027,0,14.534-6.507,14.534-14.534C30.534,7.973,24.027,1.466,16,1.466z M17.328,24.371h-2.707v-2.596h2.707V24.371zM17.328,19.003v0.858h-2.707v-1.057c0-3.19,3.63-3.696,3.63-5.963c0-1.034-0.924-1.826-2.134-1.826c-1.254,0-2.354,0.924-2.354,0.924l-1.541-1.915c0,0,1.519-1.584,4.137-1.584c2.487,0,4.796,1.54,4.796,4.136C21.156,16.208,17.328,16.627,17.328,19.003z";

    var wrapper = document.createElement("span");
    wrapper.className = "cesium-navigationHelpButton-wrapper";
    container.appendChild(wrapper);

    var button = document.createElement("button");
    button.type = "button";
    button.className =
      "cesium-button cesium-toolbar-button cesium-navigation-help-button";
    button.setAttribute(
      "data-bind",
      "\
attr: { title: tooltip },\
click: command,\
cesiumSvgPath: { path: _svgPath, width: 32, height: 32 }"
    );
    wrapper.appendChild(button);

    var instructionContainer = document.createElement("div");
    instructionContainer.className = "cesium-navigation-help";
    instructionContainer.setAttribute(
      "data-bind",
      'css: { "cesium-navigation-help-visible" : showInstructions}'
    );
    wrapper.appendChild(instructionContainer);

    var mouseButton = document.createElement("button");
    mouseButton.type = "button";
    mouseButton.className =
      "cesium-navigation-button cesium-navigation-button-left";
    mouseButton.setAttribute(
      "data-bind",
      'click: showClick, css: {"cesium-navigation-button-selected": !_touch, "cesium-navigation-button-unselected": _touch}'
    );
    var mouseIcon = document.createElement("img");
    mouseIcon.src = buildModuleUrl("Widgets/Images/NavigationHelp/Mouse.svg");
    mouseIcon.className = "cesium-navigation-button-icon";
    mouseIcon.style.width = "25px";
    mouseIcon.style.height = "25px";
    mouseButton.appendChild(mouseIcon);
    mouseButton.appendChild(document.createTextNode("Mouse"));

    var touchButton = document.createElement("button");
    touchButton.type = "button";
    touchButton.className =
      "cesium-navigation-button cesium-navigation-button-right";
    touchButton.setAttribute(
      "data-bind",
      'click: showTouch, css: {"cesium-navigation-button-selected": _touch, "cesium-navigation-button-unselected": !_touch}'
    );
    var touchIcon = document.createElement("img");
    touchIcon.src = buildModuleUrl("Widgets/Images/NavigationHelp/Touch.svg");
    touchIcon.className = "cesium-navigation-button-icon";
    touchIcon.style.width = "25px";
    touchIcon.style.height = "25px";
    touchButton.appendChild(touchIcon);
    touchButton.appendChild(document.createTextNode("Touch"));

    instructionContainer.appendChild(mouseButton);
    instructionContainer.appendChild(touchButton);

    var clickInstructions = document.createElement("div");
    clickInstructions.className =
      "cesium-click-navigation-help cesium-navigation-help-instructions";
    clickInstructions.setAttribute(
      "data-bind",
      'css: { "cesium-click-navigation-help-visible" : !_touch}'
    );
    clickInstructions.innerHTML =
      '\
            <table>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/MouseLeft.svg") +
      '" width="48" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-pan">Pan view</div>\
                        <div class="cesium-navigation-help-details">Left click + drag</div>\
                    </td>\
                </tr>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/MouseRight.svg") +
      '" width="48" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-zoom">Zoom view</div>\
                        <div class="cesium-navigation-help-details">Right click + drag, or</div>\
                        <div class="cesium-navigation-help-details">Mouse wheel scroll</div>\
                    </td>\
                </tr>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/MouseMiddle.svg") +
      '" width="48" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-rotate">Rotate view</div>\
                        <div class="cesium-navigation-help-details">Middle click + drag, or</div>\
                        <div class="cesium-navigation-help-details">CTRL + Left/Right click + drag</div>\
                    </td>\
                </tr>\
            </table>';

    instructionContainer.appendChild(clickInstructions);

    var touchInstructions = document.createElement("div");
    touchInstructions.className =
      "cesium-touch-navigation-help cesium-navigation-help-instructions";
    touchInstructions.setAttribute(
      "data-bind",
      'css: { "cesium-touch-navigation-help-visible" : _touch}'
    );
    touchInstructions.innerHTML =
      '\
            <table>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/TouchDrag.svg") +
      '" width="70" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-pan">Pan view</div>\
                        <div class="cesium-navigation-help-details">One finger drag</div>\
                    </td>\
                </tr>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/TouchZoom.svg") +
      '" width="70" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-zoom">Zoom view</div>\
                        <div class="cesium-navigation-help-details">Two finger pinch</div>\
                    </td>\
                </tr>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/TouchTilt.svg") +
      '" width="70" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-rotate">Tilt view</div>\
                        <div class="cesium-navigation-help-details">Two finger drag, same direction</div>\
                    </td>\
                </tr>\
                <tr>\
                    <td><img src="' +
      buildModuleUrl("Widgets/Images/NavigationHelp/TouchRotate.svg") +
      '" width="70" height="48" /></td>\
                    <td>\
                        <div class="cesium-navigation-help-tilt">Rotate view</div>\
                        <div class="cesium-navigation-help-details">Two finger drag, opposite direction</div>\
                    </td>\
                </tr>\
            </table>';

    instructionContainer.appendChild(touchInstructions);

    knockout.applyBindings(viewModel, wrapper);

    this._container = container;
    this._viewModel = viewModel;
    this._wrapper = wrapper;

    this._closeInstructions = function (e) {
      if (!wrapper.contains(e.target)) {
        viewModel.showInstructions = false;
      }
    };

    if (FeatureDetection.supportsPointerEvents()) {
      document.addEventListener("pointerdown", this._closeInstructions, true);
    } else {
      document.addEventListener("mousedown", this._closeInstructions, true);
      document.addEventListener("touchstart", this._closeInstructions, true);
    }
  }

  Object.defineProperties(NavigationHelpButton.prototype, {
    /**
     * Gets the parent container.
     * @memberof NavigationHelpButton.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof NavigationHelpButton.prototype
     *
     * @type {NavigationHelpButtonViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  NavigationHelpButton.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  NavigationHelpButton.prototype.destroy = function () {
    if (FeatureDetection.supportsPointerEvents()) {
      document.removeEventListener("pointerdown", this._closeInstructions, true);
    } else {
      document.removeEventListener("mousedown", this._closeInstructions, true);
      document.removeEventListener("touchstart", this._closeInstructions, true);
    }

    knockout.cleanNode(this._wrapper);
    this._container.removeChild(this._wrapper);

    return destroyObject(this);
  };

  /**
   * The view model for {@link PerformanceWatchdog}.
   *
   * @alias PerformanceWatchdogViewModel
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Scene} options.scene The Scene instance for which to monitor performance.
   * @param {String} [options.lowFrameRateMessage='This application appears to be performing poorly on your system.  Please try using a different web browser or updating your video drivers.'] The
   *        message to display when a low frame rate is detected.  The message is interpeted as HTML, so make sure
   *        it comes from a trusted source so that your application is not vulnerable to cross-site scripting attacks.
   */
  function PerformanceWatchdogViewModel(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.scene)) {
      throw new DeveloperError("options.scene is required.");
    }
    //>>includeEnd('debug');

    this._scene = options.scene;

    /**
     * Gets or sets the message to display when a low frame rate is detected.  This string will be interpreted as HTML.
     * @type {String}
     */
    this.lowFrameRateMessage = defaultValue(
      options.lowFrameRateMessage,
      "This application appears to be performing poorly on your system.  Please try using a different web browser or updating your video drivers."
    );

    /**
     * Gets or sets a value indicating whether the low frame rate message has previously been dismissed by the user.  If it has
     * been dismissed, the message will not be redisplayed, no matter the frame rate.
     * @type {Boolean}
     */
    this.lowFrameRateMessageDismissed = false;

    /**
     * Gets or sets a value indicating whether the low frame rate message is currently being displayed.
     * @type {Boolean}
     */
    this.showingLowFrameRateMessage = false;

    knockout.track(this, [
      "lowFrameRateMessage",
      "lowFrameRateMessageDismissed",
      "showingLowFrameRateMessage",
    ]);

    var that = this;
    this._dismissMessage = createCommand$2(function () {
      that.showingLowFrameRateMessage = false;
      that.lowFrameRateMessageDismissed = true;
    });

    var monitor = FrameRateMonitor.fromScene(options.scene);

    this._unsubscribeLowFrameRate = monitor.lowFrameRate.addEventListener(
      function () {
        if (!that.lowFrameRateMessageDismissed) {
          that.showingLowFrameRateMessage = true;
        }
      }
    );

    this._unsubscribeNominalFrameRate = monitor.nominalFrameRate.addEventListener(
      function () {
        that.showingLowFrameRateMessage = false;
      }
    );
  }

  Object.defineProperties(PerformanceWatchdogViewModel.prototype, {
    /**
     * Gets the {@link Scene} instance for which to monitor performance.
     * @memberof PerformanceWatchdogViewModel.prototype
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets a command that dismisses the low frame rate message.  Once it is dismissed, the message
     * will not be redisplayed.
     * @memberof PerformanceWatchdogViewModel.prototype
     * @type {Command}
     */
    dismissMessage: {
      get: function () {
        return this._dismissMessage;
      },
    },
  });

  PerformanceWatchdogViewModel.prototype.destroy = function () {
    this._unsubscribeLowFrameRate();
    this._unsubscribeNominalFrameRate();

    return destroyObject(this);
  };

  /**
   * Monitors performance of the application and displays a message if poor performance is detected.
   *
   * @alias PerformanceWatchdog
   * @constructor
   *
   * @param {Object} [options] Object with the following properties:
   * @param {Element|String} options.container The DOM element or ID that will contain the widget.
   * @param {Scene} options.scene The {@link Scene} for which to monitor performance.
   * @param {String} [options.lowFrameRateMessage='This application appears to be performing poorly on your system.  Please try using a different web browser or updating your video drivers.'] The
   *        message to display when a low frame rate is detected.  The message is interpeted as HTML, so make sure
   *        it comes from a trusted source so that your application is not vulnerable to cross-site scripting attacks.
   */
  function PerformanceWatchdog(options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(options) || !defined(options.container)) {
      throw new DeveloperError("options.container is required.");
    }
    if (!defined(options.scene)) {
      throw new DeveloperError("options.scene is required.");
    }
    //>>includeEnd('debug');

    var container = getElement(options.container);

    var viewModel = new PerformanceWatchdogViewModel(options);

    var element = document.createElement("div");
    element.className = "cesium-performance-watchdog-message-area";
    element.setAttribute("data-bind", "visible: showingLowFrameRateMessage");

    var dismissButton = document.createElement("button");
    dismissButton.setAttribute("type", "button");
    dismissButton.className = "cesium-performance-watchdog-message-dismiss";
    dismissButton.innerHTML = "&times;";
    dismissButton.setAttribute("data-bind", "click: dismissMessage");
    element.appendChild(dismissButton);

    var message = document.createElement("div");
    message.className = "cesium-performance-watchdog-message";
    message.setAttribute("data-bind", "html: lowFrameRateMessage");
    element.appendChild(message);

    container.appendChild(element);

    knockout.applyBindings(viewModel, element);

    this._container = container;
    this._viewModel = viewModel;
    this._element = element;
  }

  Object.defineProperties(PerformanceWatchdog.prototype, {
    /**
     * Gets the parent container.
     * @memberof PerformanceWatchdog.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof PerformanceWatchdog.prototype
     *
     * @type {PerformanceWatchdogViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @memberof PerformanceWatchdog
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  PerformanceWatchdog.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   * @memberof PerformanceWatchdog
   */
  PerformanceWatchdog.prototype.destroy = function () {
    this._viewModel.destroy();
    knockout.cleanNode(this._element);
    this._container.removeChild(this._element);

    return destroyObject(this);
  };

  /**
   * The view model for {@link ProjectionPicker}.
   * @alias ProjectionPickerViewModel
   * @constructor
   *
   * @param {Scene} scene The Scene to switch projections.
   */
  function ProjectionPickerViewModel(scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    this._scene = scene;
    this._orthographic = scene.camera.frustum instanceof OrthographicFrustum;
    this._flightInProgress = false;

    /**
     * Gets or sets whether the button drop-down is currently visible.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.dropDownVisible = false;

    /**
     * Gets or sets the perspective projection tooltip.  This property is observable.
     * @type {String}
     * @default 'Perspective Projection'
     */
    this.tooltipPerspective = "Perspective Projection";

    /**
     * Gets or sets the orthographic projection tooltip.  This property is observable.
     * @type {String}
     * @default 'Orthographic Projection'
     */
    this.tooltipOrthographic = "Orthographic Projection";

    /**
     * Gets the currently active tooltip.  This property is observable.
     * @type {String}
     */
    this.selectedTooltip = undefined;

    /**
     * Gets or sets the current SceneMode.  This property is observable.
     * @type {SceneMode}
     */
    this.sceneMode = scene.mode;

    knockout.track(this, [
      "_orthographic",
      "_flightInProgress",
      "sceneMode",
      "dropDownVisible",
      "tooltipPerspective",
      "tooltipOrthographic",
    ]);

    var that = this;
    knockout.defineProperty(this, "selectedTooltip", function () {
      if (that._orthographic) {
        return that.tooltipOrthographic;
      }
      return that.tooltipPerspective;
    });

    this._toggleDropDown = createCommand$2(function () {
      if (that.sceneMode === SceneMode$1.SCENE2D || that._flightInProgress) {
        return;
      }

      that.dropDownVisible = !that.dropDownVisible;
    });

    this._eventHelper = new EventHelper();
    this._eventHelper.add(scene.morphComplete, function (
      transitioner,
      oldMode,
      newMode,
      isMorphing
    ) {
      that.sceneMode = newMode;
      that._orthographic =
        newMode === SceneMode$1.SCENE2D ||
        that._scene.camera.frustum instanceof OrthographicFrustum;
    });
    this._eventHelper.add(scene.preRender, function () {
      that._flightInProgress = defined(scene.camera._currentFlight);
    });

    this._switchToPerspective = createCommand$2(function () {
      if (that.sceneMode === SceneMode$1.SCENE2D) {
        return;
      }

      that._scene.camera.switchToPerspectiveFrustum();
      that._orthographic = false;
      that.dropDownVisible = false;
    });

    this._switchToOrthographic = createCommand$2(function () {
      if (that.sceneMode === SceneMode$1.SCENE2D) {
        return;
      }

      that._scene.camera.switchToOrthographicFrustum();
      that._orthographic = true;
      that.dropDownVisible = false;
    });

    //Used by knockout
    this._sceneMode = SceneMode$1;
  }

  Object.defineProperties(ProjectionPickerViewModel.prototype, {
    /**
     * Gets the scene
     * @memberof ProjectionPickerViewModel.prototype
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets the command to toggle the drop down box.
     * @memberof ProjectionPickerViewModel.prototype
     *
     * @type {Command}
     */
    toggleDropDown: {
      get: function () {
        return this._toggleDropDown;
      },
    },

    /**
     * Gets the command to switch to a perspective projection.
     * @memberof ProjectionPickerViewModel.prototype
     *
     * @type {Command}
     */
    switchToPerspective: {
      get: function () {
        return this._switchToPerspective;
      },
    },

    /**
     * Gets the command to switch to orthographic projection.
     * @memberof ProjectionPickerViewModel.prototype
     *
     * @type {Command}
     */
    switchToOrthographic: {
      get: function () {
        return this._switchToOrthographic;
      },
    },

    /**
     * Gets whether the scene is currently using an orthographic projection.
     * @memberof ProjectionPickerViewModel.prototype
     *
     * @type {Command}
     */
    isOrthographicProjection: {
      get: function () {
        return this._orthographic;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  ProjectionPickerViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the view model.
   */
  ProjectionPickerViewModel.prototype.destroy = function () {
    this._eventHelper.removeAll();
    destroyObject(this);
  };

  var perspectivePath =
    "M 28.15625,10.4375 9.125,13.21875 13.75,43.25 41.75,55.09375 50.8125,37 54.5,11.9375 z m 0.125,3 19.976451,0.394265 L 43.03125,16.875 22.6875,14.28125 z M 50.971746,15.705477 47.90625,36.03125 42.53125,46 44.84375,19.3125 z M 12.625,16.03125 l 29.15625,3.6875 -2.65625,31 L 16.4375,41.125 z";
  var orthographicPath =
    "m 31.560594,6.5254438 -20.75,12.4687502 0.1875,24.5625 22.28125,11.8125 19.5,-12 0.65625,-0.375 0,-0.75 0.0312,-23.21875 z m 0.0625,3.125 16.65625,9.5000002 -16.125,10.28125 -17.34375,-9.71875 z m 18.96875,11.1875002 0.15625,20.65625 -17.46875,10.59375 0.15625,-20.28125 z m -37.0625,1.25 17.21875,9.625 -0.15625,19.21875 -16.9375,-9 z";

  /**
   * The ProjectionPicker is a single button widget for switching between perspective and orthographic projections.
   *
   * @alias ProjectionPicker
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene The Scene instance to use.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   * @example
   * // In HTML head, include a link to the ProjectionPicker.css stylesheet,
   * // and in the body, include: <div id="projectionPickerContainer"></div>
   * // Note: This code assumes you already have a Scene instance.
   *
   * var projectionPicker = new Cesium.ProjectionPicker('projectionPickerContainer', scene);
   */
  function ProjectionPicker(container, scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var viewModel = new ProjectionPickerViewModel(scene);

    viewModel._perspectivePath = perspectivePath;
    viewModel._orthographicPath = orthographicPath;

    var wrapper = document.createElement("span");
    wrapper.className = "cesium-projectionPicker-wrapper cesium-toolbar-button";
    container.appendChild(wrapper);

    var button = document.createElement("button");
    button.type = "button";
    button.className = "cesium-button cesium-toolbar-button";
    button.setAttribute(
      "data-bind",
      '\
css: { "cesium-projectionPicker-buttonPerspective": !_orthographic,\
       "cesium-projectionPicker-buttonOrthographic": _orthographic,\
       "cesium-button-disabled" : sceneMode === _sceneMode.SCENE2D || _flightInProgress, \
       "cesium-projectionPicker-selected": dropDownVisible },\
attr: { title: selectedTooltip },\
click: toggleDropDown'
    );
    button.innerHTML =
      '\
<!-- ko cesiumSvgPath: { path: _perspectivePath, width: 64, height: 64, css: "cesium-projectionPicker-iconPerspective" } --><!-- /ko -->\
<!-- ko cesiumSvgPath: { path: _orthographicPath, width: 64, height: 64, css: "cesium-projectionPicker-iconOrthographic" } --><!-- /ko -->';
    wrapper.appendChild(button);

    var perspectiveButton = document.createElement("button");
    perspectiveButton.type = "button";
    perspectiveButton.className =
      "cesium-button cesium-toolbar-button cesium-projectionPicker-dropDown-icon";
    perspectiveButton.setAttribute(
      "data-bind",
      '\
css: { "cesium-projectionPicker-visible" : (dropDownVisible && _orthographic),\
       "cesium-projectionPicker-none" : !_orthographic,\
       "cesium-projectionPicker-hidden" : !dropDownVisible },\
attr: { title: tooltipPerspective },\
click: switchToPerspective,\
cesiumSvgPath: { path: _perspectivePath, width: 64, height: 64 }'
    );
    wrapper.appendChild(perspectiveButton);

    var orthographicButton = document.createElement("button");
    orthographicButton.type = "button";
    orthographicButton.className =
      "cesium-button cesium-toolbar-button cesium-projectionPicker-dropDown-icon";
    orthographicButton.setAttribute(
      "data-bind",
      '\
css: { "cesium-projectionPicker-visible" : (dropDownVisible && !_orthographic),\
       "cesium-projectionPicker-none" : _orthographic,\
       "cesium-projectionPicker-hidden" : !dropDownVisible},\
attr: { title: tooltipOrthographic },\
click: switchToOrthographic,\
cesiumSvgPath: { path: _orthographicPath, width: 64, height: 64 }'
    );
    wrapper.appendChild(orthographicButton);

    knockout.applyBindings(viewModel, wrapper);

    this._viewModel = viewModel;
    this._container = container;
    this._wrapper = wrapper;

    this._closeDropDown = function (e) {
      if (!wrapper.contains(e.target)) {
        viewModel.dropDownVisible = false;
      }
    };
    if (FeatureDetection.supportsPointerEvents()) {
      document.addEventListener("pointerdown", this._closeDropDown, true);
    } else {
      document.addEventListener("mousedown", this._closeDropDown, true);
      document.addEventListener("touchstart", this._closeDropDown, true);
    }
  }

  Object.defineProperties(ProjectionPicker.prototype, {
    /**
     * Gets the parent container.
     * @memberof ProjectionPicker.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof ProjectionPicker.prototype
     *
     * @type {ProjectionPickerViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  ProjectionPicker.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  ProjectionPicker.prototype.destroy = function () {
    this._viewModel.destroy();

    if (FeatureDetection.supportsPointerEvents()) {
      document.removeEventListener("pointerdown", this._closeDropDown, true);
    } else {
      document.removeEventListener("mousedown", this._closeDropDown, true);
      document.removeEventListener("touchstart", this._closeDropDown, true);
    }

    knockout.cleanNode(this._wrapper);
    this._container.removeChild(this._wrapper);

    return destroyObject(this);
  };

  /**
   * The view model for {@link SceneModePicker}.
   * @alias SceneModePickerViewModel
   * @constructor
   *
   * @param {Scene} scene The Scene to morph
   * @param {Number} [duration=2.0] The duration of scene morph animations, in seconds
   */
  function SceneModePickerViewModel(scene, duration) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    this._scene = scene;

    var that = this;

    var morphStart = function (transitioner, oldMode, newMode, isMorphing) {
      that.sceneMode = newMode;
      that.dropDownVisible = false;
    };

    this._eventHelper = new EventHelper();
    this._eventHelper.add(scene.morphStart, morphStart);

    this._duration = defaultValue(duration, 2.0);

    /**
     * Gets or sets the current SceneMode.  This property is observable.
     * @type {SceneMode}
     */
    this.sceneMode = scene.mode;

    /**
     * Gets or sets whether the button drop-down is currently visible.  This property is observable.
     * @type {Boolean}
     * @default false
     */
    this.dropDownVisible = false;

    /**
     * Gets or sets the 2D tooltip.  This property is observable.
     * @type {String}
     * @default '2D'
     */
    this.tooltip2D = "2D";

    /**
     * Gets or sets the 3D tooltip.  This property is observable.
     * @type {String}
     * @default '3D'
     */
    this.tooltip3D = "3D";

    /**
     * Gets or sets the Columbus View tooltip.  This property is observable.
     * @type {String}
     * @default 'Columbus View'
     */
    this.tooltipColumbusView = "Columbus View";

    knockout.track(this, [
      "sceneMode",
      "dropDownVisible",
      "tooltip2D",
      "tooltip3D",
      "tooltipColumbusView",
    ]);

    /**
     * Gets the currently active tooltip.  This property is observable.
     * @type {String}
     */
    this.selectedTooltip = undefined;
    knockout.defineProperty(this, "selectedTooltip", function () {
      var mode = that.sceneMode;
      if (mode === SceneMode$1.SCENE2D) {
        return that.tooltip2D;
      }
      if (mode === SceneMode$1.SCENE3D) {
        return that.tooltip3D;
      }
      return that.tooltipColumbusView;
    });

    this._toggleDropDown = createCommand$2(function () {
      that.dropDownVisible = !that.dropDownVisible;
    });

    this._morphTo2D = createCommand$2(function () {
      scene.morphTo2D(that._duration);
    });

    this._morphTo3D = createCommand$2(function () {
      scene.morphTo3D(that._duration);
    });

    this._morphToColumbusView = createCommand$2(function () {
      scene.morphToColumbusView(that._duration);
    });

    //Used by knockout
    this._sceneMode = SceneMode$1;
  }

  Object.defineProperties(SceneModePickerViewModel.prototype, {
    /**
     * Gets the scene
     * @memberof SceneModePickerViewModel.prototype
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },

    /**
     * Gets or sets the the duration of scene mode transition animations in seconds.
     * A value of zero causes the scene to instantly change modes.
     * @memberof SceneModePickerViewModel.prototype
     * @type {Number}
     */
    duration: {
      get: function () {
        return this._duration;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (value < 0.0) {
          throw new DeveloperError("duration value must be positive.");
        }
        //>>includeEnd('debug');

        this._duration = value;
      },
    },

    /**
     * Gets the command to toggle the drop down box.
     * @memberof SceneModePickerViewModel.prototype
     *
     * @type {Command}
     */
    toggleDropDown: {
      get: function () {
        return this._toggleDropDown;
      },
    },

    /**
     * Gets the command to morph to 2D.
     * @memberof SceneModePickerViewModel.prototype
     *
     * @type {Command}
     */
    morphTo2D: {
      get: function () {
        return this._morphTo2D;
      },
    },

    /**
     * Gets the command to morph to 3D.
     * @memberof SceneModePickerViewModel.prototype
     *
     * @type {Command}
     */
    morphTo3D: {
      get: function () {
        return this._morphTo3D;
      },
    },

    /**
     * Gets the command to morph to Columbus View.
     * @memberof SceneModePickerViewModel.prototype
     *
     * @type {Command}
     */
    morphToColumbusView: {
      get: function () {
        return this._morphToColumbusView;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  SceneModePickerViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the view model.
   */
  SceneModePickerViewModel.prototype.destroy = function () {
    this._eventHelper.removeAll();

    destroyObject(this);
  };

  var globePath =
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        -3.47e-4,-2.2e-4 -0.133444,-0.03532 -0.244525,-0.06987 C 51.944299,13.447603 51.751076,13.104317 51.474391,12.827728 46.462556,7.8176457 39.488996,4.9330437 32.401392,4.9330437 z m -2.130866,3.5281554 0.104797,9.6762289 c -4.111695,-0.08361 -7.109829,-0.423664 -9.257041,-0.943171 1.198093,-2.269271 2.524531,-4.124404 3.91241,-5.414496 2.167498,-2.0147811 3.950145,-2.8540169 5.239834,-3.3185619 z m 2.794579,0 c 1.280302,0.4754953 3.022186,1.3285948 5.065173,3.2486979 1.424667,1.338973 2.788862,3.303645 3.982275,5.728886 -2.29082,0.403367 -5.381258,0.621049 -8.942651,0.698645 L 33.065105,8.4611991 z m 5.728886,0.2445256 c 4.004072,1.1230822 7.793098,3.1481363 10.724195,6.0782083 0.03468,0.03466 0.07033,0.06991 0.104797,0.104797 -0.45375,0.313891 -0.923054,0.663002 -1.956205,1.082899 -0.647388,0.263114 -1.906242,0.477396 -2.829511,0.733577 -1.382296,-2.988132 \
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        M 8.2632205,30.922625 c 0.7558676,0.510548 1.5529563,1.013339 3.0041715,1.57195 0.937518,0.360875 2.612202,0.647642 3.91241,0.978102 0.112814,3.85566 0.703989,7.107756 1.606883,9.920754 -1.147172,-0.324262 -2.644553,-0.640648 -3.423359,-0.978102 -1.516688,-0.657177 -2.386627,-1.287332 -2.864443,-1.71168 -0.477816,-0.424347 -0.489051,-0.489051 -0.489051,-0.489051 L 9.8002387,40.319395 C 8.791691,37.621767 8.1584238,34.769583 8.1584238,31.900727 c 0,-0.330153 0.090589,-0.648169 0.1047967,-0.978102 z m 48.2763445,0.419186 c 0.0047,0.188973 0.06986,0.36991 0.06986,0.558916 0,2.938869 -0.620228,5.873558 -1.676747,8.628261 -0.07435,0.07583 -0.06552,0.07411 -0.454119,0.349323 -0.606965,0.429857 -1.631665,1.042044 -3.318562,1.676747 -1.208528,0.454713 -3.204964,0.850894 -5.135038,1.25756 0.84593,-2.765726 1.41808,-6.005357 1.606883,-9.815957 2.232369,-0.413371 4.483758,-0.840201 \
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        -3.213765,4.156936 -2.74253,2.741571 -6.244106,4.696717 -9.955686,5.868615 0.261347,-0.241079 0.507495,-0.394491 0.768509,-0.663713 1.674841,-1.727516 3.320792,-4.181056 4.645987,-7.265904 2.962447,-0.503021 5.408965,-1.122293 7.161107,-1.781544 0.284034,-0.106865 0.337297,-0.207323 0.593848,-0.31439 z m -31.404076,2.305527 c 2.645807,0.376448 5.701178,0.649995 9.466635,0.698645 l 0.139729,7.789888 c -1.38739,-0.480844 -3.316218,-1.29837 -5.659022,-3.388427 -1.388822,-1.238993 -2.743668,-3.0113 -3.947342,-5.100106 z m 20.365491,0.104797 c -1.04872,2.041937 -2.174337,3.779068 -3.353494,4.995309 -1.853177,1.911459 -3.425515,2.82679 -4.611055,3.353494 l -0.139729,-7.789887 c 3.13091,-0.05714 5.728238,-0.278725 8.104278,-0.558916 z";
  var flatMapPath =
    "m 2.9825053,17.550598 0,1.368113 0,26.267766 0,1.368113 1.36811,0 54.9981397,0 1.36811,0 0,-1.368113 0,-26.267766 0,-1.368113 -1.36811,0 -54.9981397,0 -1.36811,0 z m 2.73623,2.736226 10.3292497,0 0,10.466063 -10.3292497,0 0,-10.466063 z m 13.0654697,0 11.69737,0 0,10.466063 -11.69737,0 0,-10.466063 z m 14.43359,0 11.69737,0 0,10.466063 -11.69737,0 0,-10.466063 z m 14.43359,0 10.32926,0 0,10.466063 -10.32926,0 0,-10.466063 z m -41.9326497,13.202288 10.3292497,0 0,10.329252 -10.3292497,0 0,-10.329252 z m 13.0654697,0 11.69737,0 0,10.329252 -11.69737,0 0,-10.329252 z m 14.43359,0 11.69737,0 0,10.329252 -11.69737,0 0,-10.329252 z m 14.43359,0 10.32926,0 0,10.329252 -10.32926,0 0,-10.329252 z";
  var columbusViewPath =
    "m 14.723969,17.675598 -0.340489,0.817175 -11.1680536,26.183638 -0.817175,1.872692 2.076986,0 54.7506996,0 2.07698,0 -0.81717,-1.872692 -11.16805,-26.183638 -0.34049,-0.817175 -0.91933,0 -32.414586,0 -0.919322,0 z m 1.838643,2.723916 6.196908,0 -2.928209,10.418977 -7.729111,0 4.460412,-10.418977 z m 9.02297,0 4.903049,0 0,10.418977 -7.831258,0 2.928209,-10.418977 z m 7.626964,0 5.584031,0 2.62176,10.418977 -8.205791,0 0,-10.418977 z m 8.410081,0 5.51593,0 4.46042,10.418977 -7.38863,0 -2.58772,-10.418977 z m -30.678091,13.142892 8.103649,0 -2.89416,10.282782 -9.6018026,0 4.3923136,-10.282782 z m 10.929711,0 8.614384,0 0,10.282782 -11.508544,0 2.89416,-10.282782 z m 11.338299,0 8.852721,0 2.58772,10.282782 -11.440441,0 0,-10.282782 z m 11.678781,0 7.86531,0 4.39231,10.282782 -9.6699,0 -2.58772,-10.282782 z";

  /**
   * <img src="Images/sceneModePicker.png" style="float: left; margin-right: 10px;" width="44" height="116" />
   * <p>The SceneModePicker is a single button widget for switching between scene modes;
   * shown to the left in its expanded state. Programatic switching of scene modes will
   * be automatically reflected in the widget as long as the specified Scene
   * is used to perform the change.</p><p style="clear: both;"></p><br/>
   *
   * @alias SceneModePicker
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene The Scene instance to use.
   * @param {Number} [duration=2.0] The time, in seconds, it takes for the scene to transition.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   *
   * @example
   * // In HTML head, include a link to the SceneModePicker.css stylesheet,
   * // and in the body, include: <div id="sceneModePickerContainer"></div>
   * // Note: This code assumes you already have a Scene instance.
   *
   * var sceneModePicker = new Cesium.SceneModePicker('sceneModePickerContainer', scene);
   */
  function SceneModePicker(container, scene, duration) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var viewModel = new SceneModePickerViewModel(scene, duration);

    viewModel._globePath = globePath;
    viewModel._flatMapPath = flatMapPath;
    viewModel._columbusViewPath = columbusViewPath;

    var wrapper = document.createElement("span");
    wrapper.className = "cesium-sceneModePicker-wrapper cesium-toolbar-button";
    container.appendChild(wrapper);

    var button = document.createElement("button");
    button.type = "button";
    button.className = "cesium-button cesium-toolbar-button";
    button.setAttribute(
      "data-bind",
      '\
css: { "cesium-sceneModePicker-button2D": sceneMode === _sceneMode.SCENE2D,\
       "cesium-sceneModePicker-button3D": sceneMode === _sceneMode.SCENE3D,\
       "cesium-sceneModePicker-buttonColumbusView": sceneMode === _sceneMode.COLUMBUS_VIEW,\
       "cesium-sceneModePicker-selected": dropDownVisible },\
attr: { title: selectedTooltip },\
click: toggleDropDown'
    );
    button.innerHTML =
      '\
<!-- ko cesiumSvgPath: { path: _globePath, width: 64, height: 64, css: "cesium-sceneModePicker-slide-svg cesium-sceneModePicker-icon3D" } --><!-- /ko -->\
<!-- ko cesiumSvgPath: { path: _flatMapPath, width: 64, height: 64, css: "cesium-sceneModePicker-slide-svg cesium-sceneModePicker-icon2D" } --><!-- /ko -->\
<!-- ko cesiumSvgPath: { path: _columbusViewPath, width: 64, height: 64, css: "cesium-sceneModePicker-slide-svg cesium-sceneModePicker-iconColumbusView" } --><!-- /ko -->';
    wrapper.appendChild(button);

    var morphTo3DButton = document.createElement("button");
    morphTo3DButton.type = "button";
    morphTo3DButton.className =
      "cesium-button cesium-toolbar-button cesium-sceneModePicker-dropDown-icon";
    morphTo3DButton.setAttribute(
      "data-bind",
      '\
css: { "cesium-sceneModePicker-visible" : (dropDownVisible && (sceneMode !== _sceneMode.SCENE3D)) || (!dropDownVisible && (sceneMode === _sceneMode.SCENE3D)),\
       "cesium-sceneModePicker-none" : sceneMode === _sceneMode.SCENE3D,\
       "cesium-sceneModePicker-hidden" : !dropDownVisible },\
attr: { title: tooltip3D },\
click: morphTo3D,\
cesiumSvgPath: { path: _globePath, width: 64, height: 64 }'
    );
    wrapper.appendChild(morphTo3DButton);

    var morphTo2DButton = document.createElement("button");
    morphTo2DButton.type = "button";
    morphTo2DButton.className =
      "cesium-button cesium-toolbar-button cesium-sceneModePicker-dropDown-icon";
    morphTo2DButton.setAttribute(
      "data-bind",
      '\
css: { "cesium-sceneModePicker-visible" : (dropDownVisible && (sceneMode !== _sceneMode.SCENE2D)),\
       "cesium-sceneModePicker-none" : sceneMode === _sceneMode.SCENE2D,\
       "cesium-sceneModePicker-hidden" : !dropDownVisible },\
attr: { title: tooltip2D },\
click: morphTo2D,\
cesiumSvgPath: { path: _flatMapPath, width: 64, height: 64 }'
    );
    wrapper.appendChild(morphTo2DButton);

    var morphToCVButton = document.createElement("button");
    morphToCVButton.type = "button";
    morphToCVButton.className =
      "cesium-button cesium-toolbar-button cesium-sceneModePicker-dropDown-icon";
    morphToCVButton.setAttribute(
      "data-bind",
      '\
css: { "cesium-sceneModePicker-visible" : (dropDownVisible && (sceneMode !== _sceneMode.COLUMBUS_VIEW)) || (!dropDownVisible && (sceneMode === _sceneMode.COLUMBUS_VIEW)),\
       "cesium-sceneModePicker-none" : sceneMode === _sceneMode.COLUMBUS_VIEW,\
       "cesium-sceneModePicker-hidden" : !dropDownVisible},\
attr: { title: tooltipColumbusView },\
click: morphToColumbusView,\
cesiumSvgPath: { path: _columbusViewPath, width: 64, height: 64 }'
    );
    wrapper.appendChild(morphToCVButton);

    knockout.applyBindings(viewModel, wrapper);

    this._viewModel = viewModel;
    this._container = container;
    this._wrapper = wrapper;

    this._closeDropDown = function (e) {
      if (!wrapper.contains(e.target)) {
        viewModel.dropDownVisible = false;
      }
    };
    if (FeatureDetection.supportsPointerEvents()) {
      document.addEventListener("pointerdown", this._closeDropDown, true);
    } else {
      document.addEventListener("mousedown", this._closeDropDown, true);
      document.addEventListener("touchstart", this._closeDropDown, true);
    }
  }

  Object.defineProperties(SceneModePicker.prototype, {
    /**
     * Gets the parent container.
     * @memberof SceneModePicker.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof SceneModePicker.prototype
     *
     * @type {SceneModePickerViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  SceneModePicker.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  SceneModePicker.prototype.destroy = function () {
    this._viewModel.destroy();

    if (FeatureDetection.supportsPointerEvents()) {
      document.removeEventListener("pointerdown", this._closeDropDown, true);
    } else {
      document.removeEventListener("mousedown", this._closeDropDown, true);
      document.removeEventListener("touchstart", this._closeDropDown, true);
    }

    knockout.cleanNode(this._wrapper);
    this._container.removeChild(this._wrapper);

    return destroyObject(this);
  };

  var screenSpacePos = new Cartesian2();
  var offScreen = "-1000px";

  /**
   * The view model for {@link SelectionIndicator}.
   * @alias SelectionIndicatorViewModel
   * @constructor
   *
   * @param {Scene} scene The scene instance to use for screen-space coordinate conversion.
   * @param {Element} selectionIndicatorElement The element containing all elements that make up the selection indicator.
   * @param {Element} container The DOM element that contains the widget.
   */
  function SelectionIndicatorViewModel(
    scene,
    selectionIndicatorElement,
    container
  ) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }

    if (!defined(selectionIndicatorElement)) {
      throw new DeveloperError("selectionIndicatorElement is required.");
    }

    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug')

    this._scene = scene;
    this._screenPositionX = offScreen;
    this._screenPositionY = offScreen;
    this._tweens = scene.tweens;
    this._container = defaultValue(container, document.body);
    this._selectionIndicatorElement = selectionIndicatorElement;
    this._scale = 1;

    /**
     * Gets or sets the world position of the object for which to display the selection indicator.
     * @type {Cartesian3}
     */
    this.position = undefined;

    /**
     * Gets or sets the visibility of the selection indicator.
     * @type {Boolean}
     */
    this.showSelection = false;

    knockout.track(this, [
      "position",
      "_screenPositionX",
      "_screenPositionY",
      "_scale",
      "showSelection",
    ]);

    /**
     * Gets the visibility of the position indicator.  This can be false even if an
     * object is selected, when the selected object has no position.
     * @type {Boolean}
     */
    this.isVisible = undefined;
    knockout.defineProperty(this, "isVisible", {
      get: function () {
        return this.showSelection && defined(this.position);
      },
    });

    knockout.defineProperty(this, "_transform", {
      get: function () {
        return "scale(" + this._scale + ")";
      },
    });

    /**
     * Gets or sets the function for converting the world position of the object to the screen space position.
     *
     * @member
     * @type {SelectionIndicatorViewModel.ComputeScreenSpacePosition}
     * @default SceneTransforms.wgs84ToWindowCoordinates
     *
     * @example
     * selectionIndicatorViewModel.computeScreenSpacePosition = function(position, result) {
     *     return Cesium.SceneTransforms.wgs84ToWindowCoordinates(scene, position, result);
     * };
     */
    this.computeScreenSpacePosition = function (position, result) {
      return SceneTransforms.wgs84ToWindowCoordinates(scene, position, result);
    };
  }

  /**
   * Updates the view of the selection indicator to match the position and content properties of the view model.
   * This function should be called as part of the render loop.
   */
  SelectionIndicatorViewModel.prototype.update = function () {
    if (this.showSelection && defined(this.position)) {
      var screenPosition = this.computeScreenSpacePosition(
        this.position,
        screenSpacePos
      );
      if (!defined(screenPosition)) {
        this._screenPositionX = offScreen;
        this._screenPositionY = offScreen;
      } else {
        var container = this._container;
        var containerWidth = container.parentNode.clientWidth;
        var containerHeight = container.parentNode.clientHeight;
        var indicatorSize = this._selectionIndicatorElement.clientWidth;
        var halfSize = indicatorSize * 0.5;

        screenPosition.x =
          Math.min(
            Math.max(screenPosition.x, -indicatorSize),
            containerWidth + indicatorSize
          ) - halfSize;
        screenPosition.y =
          Math.min(
            Math.max(screenPosition.y, -indicatorSize),
            containerHeight + indicatorSize
          ) - halfSize;

        this._screenPositionX = Math.floor(screenPosition.x + 0.25) + "px";
        this._screenPositionY = Math.floor(screenPosition.y + 0.25) + "px";
      }
    }
  };

  /**
   * Animate the indicator to draw attention to the selection.
   */
  SelectionIndicatorViewModel.prototype.animateAppear = function () {
    this._tweens.addProperty({
      object: this,
      property: "_scale",
      startValue: 2,
      stopValue: 1,
      duration: 0.8,
      easingFunction: EasingFunction$1.EXPONENTIAL_OUT,
    });
  };

  /**
   * Animate the indicator to release the selection.
   */
  SelectionIndicatorViewModel.prototype.animateDepart = function () {
    this._tweens.addProperty({
      object: this,
      property: "_scale",
      startValue: this._scale,
      stopValue: 1.5,
      duration: 0.8,
      easingFunction: EasingFunction$1.EXPONENTIAL_OUT,
    });
  };

  Object.defineProperties(SelectionIndicatorViewModel.prototype, {
    /**
     * Gets the HTML element containing the selection indicator.
     * @memberof SelectionIndicatorViewModel.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the HTML element that holds the selection indicator.
     * @memberof SelectionIndicatorViewModel.prototype
     *
     * @type {Element}
     */
    selectionIndicatorElement: {
      get: function () {
        return this._selectionIndicatorElement;
      },
    },

    /**
     * Gets the scene being used.
     * @memberof SelectionIndicatorViewModel.prototype
     *
     * @type {Scene}
     */
    scene: {
      get: function () {
        return this._scene;
      },
    },
  });

  /**
   * A widget for displaying an indicator on a selected object.
   *
   * @alias SelectionIndicator
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene The Scene instance to use.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   */
  function SelectionIndicator(container, scene) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug')

    container = getElement(container);

    this._container = container;

    var el = document.createElement("div");
    el.className = "cesium-selection-wrapper";
    el.setAttribute(
      "data-bind",
      '\
style: { "top" : _screenPositionY, "left" : _screenPositionX },\
css: { "cesium-selection-wrapper-visible" : isVisible }'
    );
    container.appendChild(el);
    this._element = el;

    var svgNS = "http://www.w3.org/2000/svg";
    var path =
      "M -34 -34 L -34 -11.25 L -30 -15.25 L -30 -30 L -15.25 -30 L -11.25 -34 L -34 -34 z M 11.25 -34 L 15.25 -30 L 30 -30 L 30 -15.25 L 34 -11.25 L 34 -34 L 11.25 -34 z M -34 11.25 L -34 34 L -11.25 34 L -15.25 30 L -30 30 L -30 15.25 L -34 11.25 z M 34 11.25 L 30 15.25 L 30 30 L 15.25 30 L 11.25 34 L 34 34 L 34 11.25 z";

    var svg = document.createElementNS(svgNS, "svg:svg");
    svg.setAttribute("width", 160);
    svg.setAttribute("height", 160);
    svg.setAttribute("viewBox", "0 0 160 160");

    var group = document.createElementNS(svgNS, "g");
    group.setAttribute("transform", "translate(80,80)");
    svg.appendChild(group);

    var pathElement = document.createElementNS(svgNS, "path");
    pathElement.setAttribute("data-bind", "attr: { transform: _transform }");
    pathElement.setAttribute("d", path);
    group.appendChild(pathElement);

    el.appendChild(svg);

    var viewModel = new SelectionIndicatorViewModel(
      scene,
      this._element,
      this._container
    );
    this._viewModel = viewModel;

    knockout.applyBindings(this._viewModel, this._element);
  }

  Object.defineProperties(SelectionIndicator.prototype, {
    /**
     * Gets the parent container.
     * @memberof SelectionIndicator.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof SelectionIndicator.prototype
     *
     * @type {SelectionIndicatorViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  SelectionIndicator.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  SelectionIndicator.prototype.destroy = function () {
    var container = this._container;
    knockout.cleanNode(this._element);
    container.removeChild(this._element);
    return destroyObject(this);
  };

  /**
   * @private
   */
  function TimelineHighlightRange(color, heightInPx, base) {
    this._color = color;
    this._height = heightInPx;
    this._base = defaultValue(base, 0);
  }

  TimelineHighlightRange.prototype.getHeight = function () {
    return this._height;
  };

  TimelineHighlightRange.prototype.getBase = function () {
    return this._base;
  };

  TimelineHighlightRange.prototype.getStartTime = function () {
    return this._start;
  };

  TimelineHighlightRange.prototype.getStopTime = function () {
    return this._stop;
  };

  TimelineHighlightRange.prototype.setRange = function (start, stop) {
    this._start = start;
    this._stop = stop;
  };

  TimelineHighlightRange.prototype.render = function (renderState) {
    var range = "";
    if (this._start && this._stop && this._color) {
      var highlightStart = JulianDate.secondsDifference(
        this._start,
        renderState.epochJulian
      );
      var highlightLeft = Math.round(
        renderState.timeBarWidth * renderState.getAlpha(highlightStart)
      );
      var highlightStop = JulianDate.secondsDifference(
        this._stop,
        renderState.epochJulian
      );
      var highlightWidth =
        Math.round(
          renderState.timeBarWidth * renderState.getAlpha(highlightStop)
        ) - highlightLeft;
      if (highlightLeft < 0) {
        highlightWidth += highlightLeft;
        highlightLeft = 0;
      }
      if (highlightLeft + highlightWidth > renderState.timeBarWidth) {
        highlightWidth = renderState.timeBarWidth - highlightLeft;
      }
      if (highlightWidth > 0) {
        range =
          '<span class="cesium-timeline-highlight" style="left: ' +
          highlightLeft.toString() +
          "px; width: " +
          highlightWidth.toString() +
          "px; bottom: " +
          this._base.toString() +
          "px; height: " +
          this._height +
          "px; background-color: " +
          this._color +
          ';"></span>';
      }
    }
    return range;
  };

  /**
   * @private
   */
  function TimelineTrack(interval, pixelHeight, color, backgroundColor) {
    this.interval = interval;
    this.height = pixelHeight;
    this.color = color || new Color(0.5, 0.5, 0.5, 1.0);
    this.backgroundColor = backgroundColor || new Color(0.0, 0.0, 0.0, 0.0);
  }

  TimelineTrack.prototype.render = function (context, renderState) {
    var startInterval = this.interval.start;
    var stopInterval = this.interval.stop;

    var spanStart = renderState.startJulian;
    var spanStop = JulianDate.addSeconds(
      renderState.startJulian,
      renderState.duration,
      new JulianDate()
    );

    if (
      JulianDate.lessThan(startInterval, spanStart) &&
      JulianDate.greaterThan(stopInterval, spanStop)
    ) {
      //The track takes up the entire visible span.
      context.fillStyle = this.color.toCssColorString();
      context.fillRect(0, renderState.y, renderState.timeBarWidth, this.height);
    } else if (
      JulianDate.lessThanOrEquals(startInterval, spanStop) &&
      JulianDate.greaterThanOrEquals(stopInterval, spanStart)
    ) {
      //The track only takes up some of the visible span, compute that span.
      var x;
      var start, stop;
      for (x = 0; x < renderState.timeBarWidth; ++x) {
        var currentTime = JulianDate.addSeconds(
          renderState.startJulian,
          (x / renderState.timeBarWidth) * renderState.duration,
          new JulianDate()
        );
        if (
          !defined(start) &&
          JulianDate.greaterThanOrEquals(currentTime, startInterval)
        ) {
          start = x;
        } else if (
          !defined(stop) &&
          JulianDate.greaterThanOrEquals(currentTime, stopInterval)
        ) {
          stop = x;
        }
      }

      context.fillStyle = this.backgroundColor.toCssColorString();
      context.fillRect(0, renderState.y, renderState.timeBarWidth, this.height);

      if (defined(start)) {
        if (!defined(stop)) {
          stop = renderState.timeBarWidth;
        }
        context.fillStyle = this.color.toCssColorString();
        context.fillRect(
          start,
          renderState.y,
          Math.max(stop - start, 1),
          this.height
        );
      }
    }
  };

  var timelineWheelDelta = 1e12;

  var timelineMouseMode = {
    none: 0,
    scrub: 1,
    slide: 2,
    zoom: 3,
    touchOnly: 4,
  };
  var timelineTouchMode = {
    none: 0,
    scrub: 1,
    slideZoom: 2,
    singleTap: 3,
    ignore: 4,
  };

  var timelineTicScales = [
    0.001,
    0.002,
    0.005,
    0.01,
    0.02,
    0.05,
    0.1,
    0.25,
    0.5,
    1.0,
    2.0,
    5.0,
    10.0,
    15.0,
    30.0,
    60.0, // 1min
    120.0, // 2min
    300.0, // 5min
    600.0, // 10min
    900.0, // 15min
    1800.0, // 30min
    3600.0, // 1hr
    7200.0, // 2hr
    14400.0, // 4hr
    21600.0, // 6hr
    43200.0, // 12hr
    86400.0, // 24hr
    172800.0, // 2days
    345600.0, // 4days
    604800.0, // 7days
    1296000.0, // 15days
    2592000.0, // 30days
    5184000.0, // 60days
    7776000.0, // 90days
    15552000.0, // 180days
    31536000.0, // 365days
    63072000.0, // 2years
    126144000.0, // 4years
    157680000.0, // 5years
    315360000.0, // 10years
    630720000.0, // 20years
    1261440000.0, // 40years
    1576800000.0, // 50years
    3153600000.0, // 100years
    6307200000.0, // 200years
    12614400000.0, // 400years
    15768000000.0, // 500years
    31536000000.0, // 1000years
  ];

  var timelineMonthNames = [
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug",
    "Sep",
    "Oct",
    "Nov",
    "Dec",
  ];

  /**
   * The Timeline is a widget for displaying and controlling the current scene time.
   * @alias Timeline
   * @constructor
   *
   * @param {Element} container The parent HTML container node for this widget.
   * @param {Clock} clock The clock to use.
   */
  function Timeline(container, clock) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    if (!defined(clock)) {
      throw new DeveloperError("clock is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var ownerDocument = container.ownerDocument;

    /**
     * Gets the parent container.
     * @type {Element}
     */
    this.container = container;

    var topDiv = ownerDocument.createElement("div");
    topDiv.className = "cesium-timeline-main";
    container.appendChild(topDiv);
    this._topDiv = topDiv;

    this._endJulian = undefined;
    this._epochJulian = undefined;
    this._lastXPos = undefined;
    this._scrubElement = undefined;
    this._startJulian = undefined;
    this._timeBarSecondsSpan = undefined;
    this._clock = clock;
    this._scrubJulian = clock.currentTime;
    this._mainTicSpan = -1;
    this._mouseMode = timelineMouseMode.none;
    this._touchMode = timelineTouchMode.none;
    this._touchState = {
      centerX: 0,
      spanX: 0,
    };
    this._mouseX = 0;
    this._timelineDrag = 0;
    this._timelineDragLocation = undefined;
    this._lastHeight = undefined;
    this._lastWidth = undefined;

    this._topDiv.innerHTML =
      '<div class="cesium-timeline-bar"></div><div class="cesium-timeline-trackContainer">' +
      '<canvas class="cesium-timeline-tracks" width="10" height="1">' +
      '</canvas></div><div class="cesium-timeline-needle"></div><span class="cesium-timeline-ruler"></span>';
    this._timeBarEle = this._topDiv.childNodes[0];
    this._trackContainer = this._topDiv.childNodes[1];
    this._trackListEle = this._topDiv.childNodes[1].childNodes[0];
    this._needleEle = this._topDiv.childNodes[2];
    this._rulerEle = this._topDiv.childNodes[3];
    this._context = this._trackListEle.getContext("2d");

    this._trackList = [];
    this._highlightRanges = [];

    this.zoomTo(clock.startTime, clock.stopTime);

    this._onMouseDown = createMouseDownCallback(this);
    this._onMouseUp = createMouseUpCallback(this);
    this._onMouseMove = createMouseMoveCallback(this);
    this._onMouseWheel = createMouseWheelCallback(this);
    this._onTouchStart = createTouchStartCallback(this);
    this._onTouchMove = createTouchMoveCallback(this);
    this._onTouchEnd = createTouchEndCallback(this);

    var timeBarEle = this._timeBarEle;
    ownerDocument.addEventListener("mouseup", this._onMouseUp, false);
    ownerDocument.addEventListener("mousemove", this._onMouseMove, false);
    timeBarEle.addEventListener("mousedown", this._onMouseDown, false);
    timeBarEle.addEventListener("DOMMouseScroll", this._onMouseWheel, false); // Mozilla mouse wheel
    timeBarEle.addEventListener("mousewheel", this._onMouseWheel, false);
    timeBarEle.addEventListener("touchstart", this._onTouchStart, false);
    timeBarEle.addEventListener("touchmove", this._onTouchMove, false);
    timeBarEle.addEventListener("touchend", this._onTouchEnd, false);
    timeBarEle.addEventListener("touchcancel", this._onTouchEnd, false);

    this._topDiv.oncontextmenu = function () {
      return false;
    };

    clock.onTick.addEventListener(this.updateFromClock, this);
    this.updateFromClock();
  }

  /**
   * @private
   */
  Timeline.prototype.addEventListener = function (type, listener, useCapture) {
    this._topDiv.addEventListener(type, listener, useCapture);
  };

  /**
   * @private
   */
  Timeline.prototype.removeEventListener = function (type, listener, useCapture) {
    this._topDiv.removeEventListener(type, listener, useCapture);
  };

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  Timeline.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  Timeline.prototype.destroy = function () {
    this._clock.onTick.removeEventListener(this.updateFromClock, this);

    var doc = this.container.ownerDocument;
    doc.removeEventListener("mouseup", this._onMouseUp, false);
    doc.removeEventListener("mousemove", this._onMouseMove, false);

    var timeBarEle = this._timeBarEle;
    timeBarEle.removeEventListener("mousedown", this._onMouseDown, false);
    timeBarEle.removeEventListener("DOMMouseScroll", this._onMouseWheel, false); // Mozilla mouse wheel
    timeBarEle.removeEventListener("mousewheel", this._onMouseWheel, false);
    timeBarEle.removeEventListener("touchstart", this._onTouchStart, false);
    timeBarEle.removeEventListener("touchmove", this._onTouchMove, false);
    timeBarEle.removeEventListener("touchend", this._onTouchEnd, false);
    timeBarEle.removeEventListener("touchcancel", this._onTouchEnd, false);
    this.container.removeChild(this._topDiv);
    destroyObject(this);
  };

  /**
   * @private
   */
  Timeline.prototype.addHighlightRange = function (color, heightInPx, base) {
    var newHighlightRange = new TimelineHighlightRange(color, heightInPx, base);
    this._highlightRanges.push(newHighlightRange);
    this.resize();
    return newHighlightRange;
  };

  /**
   * @private
   */
  Timeline.prototype.addTrack = function (
    interval,
    heightInPx,
    color,
    backgroundColor
  ) {
    var newTrack = new TimelineTrack(
      interval,
      heightInPx,
      color,
      backgroundColor
    );
    this._trackList.push(newTrack);
    this._lastHeight = undefined;
    this.resize();
    return newTrack;
  };

  /**
   * Sets the view to the provided times.
   *
   * @param {JulianDate} startTime The start time.
   * @param {JulianDate} stopTime The stop time.
   */
  Timeline.prototype.zoomTo = function (startTime, stopTime) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(startTime)) {
      throw new DeveloperError("startTime is required.");
    }
    if (!defined(stopTime)) {
      throw new DeveloperError("stopTime is required");
    }
    if (JulianDate.lessThanOrEquals(stopTime, startTime)) {
      throw new DeveloperError("Start time must come before end time.");
    }
    //>>includeEnd('debug');

    this._startJulian = startTime;
    this._endJulian = stopTime;
    this._timeBarSecondsSpan = JulianDate.secondsDifference(stopTime, startTime);

    // If clock is not unbounded, clamp timeline range to clock.
    if (this._clock && this._clock.clockRange !== ClockRange$1.UNBOUNDED) {
      var clockStart = this._clock.startTime;
      var clockEnd = this._clock.stopTime;
      var clockSpan = JulianDate.secondsDifference(clockEnd, clockStart);
      var startOffset = JulianDate.secondsDifference(
        clockStart,
        this._startJulian
      );
      var endOffset = JulianDate.secondsDifference(clockEnd, this._endJulian);

      if (this._timeBarSecondsSpan >= clockSpan) {
        // if new duration longer than clock range duration, clamp to full range.
        this._timeBarSecondsSpan = clockSpan;
        this._startJulian = this._clock.startTime;
        this._endJulian = this._clock.stopTime;
      } else if (startOffset > 0) {
        // if timeline start is before clock start, shift right
        this._endJulian = JulianDate.addSeconds(
          this._endJulian,
          startOffset,
          new JulianDate()
        );
        this._startJulian = clockStart;
        this._timeBarSecondsSpan = JulianDate.secondsDifference(
          this._endJulian,
          this._startJulian
        );
      } else if (endOffset < 0) {
        // if timeline end is after clock end, shift left
        this._startJulian = JulianDate.addSeconds(
          this._startJulian,
          endOffset,
          new JulianDate()
        );
        this._endJulian = clockEnd;
        this._timeBarSecondsSpan = JulianDate.secondsDifference(
          this._endJulian,
          this._startJulian
        );
      }
    }

    this._makeTics();

    var evt = document.createEvent("Event");
    evt.initEvent("setzoom", true, true);
    evt.startJulian = this._startJulian;
    evt.endJulian = this._endJulian;
    evt.epochJulian = this._epochJulian;
    evt.totalSpan = this._timeBarSecondsSpan;
    evt.mainTicSpan = this._mainTicSpan;
    this._topDiv.dispatchEvent(evt);
  };

  /**
   * @private
   */
  Timeline.prototype.zoomFrom = function (amount) {
    var centerSec = JulianDate.secondsDifference(
      this._scrubJulian,
      this._startJulian
    );
    if (amount > 1 || centerSec < 0 || centerSec > this._timeBarSecondsSpan) {
      centerSec = this._timeBarSecondsSpan * 0.5;
    } else {
      centerSec += centerSec - this._timeBarSecondsSpan * 0.5;
    }
    var centerSecFlip = this._timeBarSecondsSpan - centerSec;
    this.zoomTo(
      JulianDate.addSeconds(
        this._startJulian,
        centerSec - centerSec * amount,
        new JulianDate()
      ),
      JulianDate.addSeconds(
        this._endJulian,
        centerSecFlip * amount - centerSecFlip,
        new JulianDate()
      )
    );
  };

  function twoDigits(num) {
    return num < 10 ? "0" + num.toString() : num.toString();
  }

  /**
   * @private
   */
  Timeline.prototype.makeLabel = function (time) {
    var gregorian = JulianDate.toGregorianDate(time);
    var millisecond = gregorian.millisecond,
      millisecondString = " UTC";
    if (millisecond > 0 && this._timeBarSecondsSpan < 3600) {
      millisecondString = Math.floor(millisecond).toString();
      while (millisecondString.length < 3) {
        millisecondString = "0" + millisecondString;
      }
      millisecondString = "." + millisecondString;
    }

    return (
      timelineMonthNames[gregorian.month - 1] +
      " " +
      gregorian.day +
      " " +
      gregorian.year +
      " " +
      twoDigits(gregorian.hour) +
      ":" +
      twoDigits(gregorian.minute) +
      ":" +
      twoDigits(gregorian.second) +
      millisecondString
    );
  };

  /**
   * @private
   */
  Timeline.prototype.smallestTicInPixels = 7.0;

  /**
   * @private
   */
  Timeline.prototype._makeTics = function () {
    var timeBar = this._timeBarEle;

    var seconds = JulianDate.secondsDifference(
      this._scrubJulian,
      this._startJulian
    );
    var xPos = Math.round(
      (seconds * this._topDiv.clientWidth) / this._timeBarSecondsSpan
    );
    var scrubX = xPos - 8,
      tic;
    var widget = this;

    this._needleEle.style.left = xPos.toString() + "px";

    var tics = "";

    var minimumDuration = 0.01;
    var maximumDuration = 31536000000.0; // ~1000 years
    var epsilon = 1e-10;

    // If time step size is known, enter it here...
    var minSize = 0;

    var duration = this._timeBarSecondsSpan;
    if (duration < minimumDuration) {
      duration = minimumDuration;
      this._timeBarSecondsSpan = minimumDuration;
      this._endJulian = JulianDate.addSeconds(
        this._startJulian,
        minimumDuration,
        new JulianDate()
      );
    } else if (duration > maximumDuration) {
      duration = maximumDuration;
      this._timeBarSecondsSpan = maximumDuration;
      this._endJulian = JulianDate.addSeconds(
        this._startJulian,
        maximumDuration,
        new JulianDate()
      );
    }

    var timeBarWidth = this._timeBarEle.clientWidth;
    if (timeBarWidth < 10) {
      timeBarWidth = 10;
    }
    var startJulian = this._startJulian;

    // epsilonTime: a small fraction of one pixel width of the timeline, measured in seconds.
    var epsilonTime = Math.min((duration / timeBarWidth) * 1e-5, 0.4);

    // epochJulian: a nearby time to be considered "zero seconds", should be a round-ish number by human standards.
    var epochJulian;
    var gregorianDate = JulianDate.toGregorianDate(startJulian);
    if (duration > 315360000) {
      // 3650+ days visible, epoch is start of the first visible century.
      epochJulian = JulianDate.fromDate(
        new Date(Date.UTC(Math.floor(gregorianDate.year / 100) * 100, 0))
      );
    } else if (duration > 31536000) {
      // 365+ days visible, epoch is start of the first visible decade.
      epochJulian = JulianDate.fromDate(
        new Date(Date.UTC(Math.floor(gregorianDate.year / 10) * 10, 0))
      );
    } else if (duration > 86400) {
      // 1+ day(s) visible, epoch is start of the year.
      epochJulian = JulianDate.fromDate(
        new Date(Date.UTC(gregorianDate.year, 0))
      );
    } else {
      // Less than a day on timeline, epoch is midnight of the visible day.
      epochJulian = JulianDate.fromDate(
        new Date(
          Date.UTC(gregorianDate.year, gregorianDate.month, gregorianDate.day)
        )
      );
    }

    // startTime: Seconds offset of the left side of the timeline from epochJulian.
    var startTime = JulianDate.secondsDifference(
      this._startJulian,
      JulianDate.addSeconds(epochJulian, epsilonTime, new JulianDate())
    );
    // endTime: Seconds offset of the right side of the timeline from epochJulian.
    var endTime = startTime + duration;
    this._epochJulian = epochJulian;

    function getStartTic(ticScale) {
      return Math.floor(startTime / ticScale) * ticScale;
    }

    function getNextTic(tic, ticScale) {
      return Math.ceil(tic / ticScale + 0.5) * ticScale;
    }

    function getAlpha(time) {
      return (time - startTime) / duration;
    }

    function remainder(x, y) {
      //return x % y;
      return x - y * Math.round(x / y);
    }

    // Width in pixels of a typical label, plus padding
    this._rulerEle.innerHTML = this.makeLabel(
      JulianDate.addSeconds(this._endJulian, -minimumDuration, new JulianDate())
    );
    var sampleWidth = this._rulerEle.offsetWidth + 20;
    if (sampleWidth < 30) {
      // Workaround an apparent IE bug with measuring the width after going full-screen from inside an iframe.
      sampleWidth = 180;
    }

    var origMinSize = minSize;
    minSize -= epsilon;

    var renderState = {
      startTime: startTime,
      startJulian: startJulian,
      epochJulian: epochJulian,
      duration: duration,
      timeBarWidth: timeBarWidth,
      getAlpha: getAlpha,
    };
    this._highlightRanges.forEach(function (highlightRange) {
      tics += highlightRange.render(renderState);
    });

    // Calculate tic mark label spacing in the TimeBar.
    var mainTic = 0.0,
      subTic = 0.0,
      tinyTic = 0.0;
    // Ideal labeled tic as percentage of zoom interval
    var idealTic = sampleWidth / timeBarWidth;
    if (idealTic > 1.0) {
      // Clamp to width of window, for thin windows.
      idealTic = 1.0;
    }
    // Ideal labeled tic size in seconds
    idealTic *= this._timeBarSecondsSpan;
    var ticIndex = -1,
      smallestIndex = -1;

    var i,
      ticScaleLen = timelineTicScales.length;
    for (i = 0; i < ticScaleLen; ++i) {
      var sc = timelineTicScales[i];
      ++ticIndex;
      mainTic = sc;
      // Find acceptable main tic size not smaller than ideal size.
      if (sc > idealTic && sc > minSize) {
        break;
      }
      if (
        smallestIndex < 0 &&
        timeBarWidth * (sc / this._timeBarSecondsSpan) >= this.smallestTicInPixels
      ) {
        smallestIndex = ticIndex;
      }
    }
    if (ticIndex > 0) {
      while (ticIndex > 0) {
        // Compute sub-tic size that evenly divides main tic.
        --ticIndex;
        if (Math.abs(remainder(mainTic, timelineTicScales[ticIndex])) < 0.00001) {
          if (timelineTicScales[ticIndex] >= minSize) {
            subTic = timelineTicScales[ticIndex];
          }
          break;
        }
      }

      if (smallestIndex >= 0) {
        while (smallestIndex < ticIndex) {
          // Compute tiny tic size that evenly divides sub-tic.
          if (
            Math.abs(remainder(subTic, timelineTicScales[smallestIndex])) <
              0.00001 &&
            timelineTicScales[smallestIndex] >= minSize
          ) {
            tinyTic = timelineTicScales[smallestIndex];
            break;
          }
          ++smallestIndex;
        }
      }
    }

    minSize = origMinSize;
    if (
      minSize > epsilon &&
      tinyTic < 0.00001 &&
      Math.abs(minSize - mainTic) > epsilon
    ) {
      tinyTic = minSize;
      if (minSize <= mainTic + epsilon) {
        subTic = 0.0;
      }
    }

    var lastTextLeft = -999999,
      textWidth;
    if (timeBarWidth * (tinyTic / this._timeBarSecondsSpan) >= 3.0) {
      for (
        tic = getStartTic(tinyTic);
        tic <= endTime;
        tic = getNextTic(tic, tinyTic)
      ) {
        tics +=
          '<span class="cesium-timeline-ticTiny" style="left: ' +
          Math.round(timeBarWidth * getAlpha(tic)).toString() +
          'px;"></span>';
      }
    }
    if (timeBarWidth * (subTic / this._timeBarSecondsSpan) >= 3.0) {
      for (
        tic = getStartTic(subTic);
        tic <= endTime;
        tic = getNextTic(tic, subTic)
      ) {
        tics +=
          '<span class="cesium-timeline-ticSub" style="left: ' +
          Math.round(timeBarWidth * getAlpha(tic)).toString() +
          'px;"></span>';
      }
    }
    if (timeBarWidth * (mainTic / this._timeBarSecondsSpan) >= 2.0) {
      this._mainTicSpan = mainTic;
      endTime += mainTic;
      tic = getStartTic(mainTic);
      var leapSecond = JulianDate.computeTaiMinusUtc(epochJulian);
      while (tic <= endTime) {
        var ticTime = JulianDate.addSeconds(
          startJulian,
          tic - startTime,
          new JulianDate()
        );
        if (mainTic > 2.1) {
          var ticLeap = JulianDate.computeTaiMinusUtc(ticTime);
          if (Math.abs(ticLeap - leapSecond) > 0.1) {
            tic += ticLeap - leapSecond;
            ticTime = JulianDate.addSeconds(
              startJulian,
              tic - startTime,
              new JulianDate()
            );
          }
        }
        var ticLeft = Math.round(timeBarWidth * getAlpha(tic));
        var ticLabel = this.makeLabel(ticTime);
        this._rulerEle.innerHTML = ticLabel;
        textWidth = this._rulerEle.offsetWidth;
        if (textWidth < 10) {
          // IE iframe fullscreen sampleWidth workaround, continued.
          textWidth = sampleWidth;
        }
        var labelLeft = ticLeft - (textWidth / 2 - 1);
        if (labelLeft > lastTextLeft) {
          lastTextLeft = labelLeft + textWidth + 5;
          tics +=
            '<span class="cesium-timeline-ticMain" style="left: ' +
            ticLeft.toString() +
            'px;"></span>' +
            '<span class="cesium-timeline-ticLabel" style="left: ' +
            labelLeft.toString() +
            'px;">' +
            ticLabel +
            "</span>";
        } else {
          tics +=
            '<span class="cesium-timeline-ticSub" style="left: ' +
            ticLeft.toString() +
            'px;"></span>';
        }
        tic = getNextTic(tic, mainTic);
      }
    } else {
      this._mainTicSpan = -1;
    }

    tics +=
      '<span class="cesium-timeline-icon16" style="left:' +
      scrubX +
      'px;bottom:0;background-position: 0 0;"></span>';
    timeBar.innerHTML = tics;
    this._scrubElement = timeBar.lastChild;

    // Clear track canvas.
    this._context.clearRect(
      0,
      0,
      this._trackListEle.width,
      this._trackListEle.height
    );

    renderState.y = 0;
    this._trackList.forEach(function (track) {
      track.render(widget._context, renderState);
      renderState.y += track.height;
    });
  };

  /**
   * @private
   */
  Timeline.prototype.updateFromClock = function () {
    this._scrubJulian = this._clock.currentTime;
    var scrubElement = this._scrubElement;
    if (defined(this._scrubElement)) {
      var seconds = JulianDate.secondsDifference(
        this._scrubJulian,
        this._startJulian
      );
      var xPos = Math.round(
        (seconds * this._topDiv.clientWidth) / this._timeBarSecondsSpan
      );

      if (this._lastXPos !== xPos) {
        this._lastXPos = xPos;

        scrubElement.style.left = xPos - 8 + "px";
        this._needleEle.style.left = xPos + "px";
      }
    }
    if (defined(this._timelineDragLocation)) {
      this._setTimeBarTime(
        this._timelineDragLocation,
        (this._timelineDragLocation * this._timeBarSecondsSpan) /
          this._topDiv.clientWidth
      );
      this.zoomTo(
        JulianDate.addSeconds(
          this._startJulian,
          this._timelineDrag,
          new JulianDate()
        ),
        JulianDate.addSeconds(
          this._endJulian,
          this._timelineDrag,
          new JulianDate()
        )
      );
    }
  };

  /**
   * @private
   */
  Timeline.prototype._setTimeBarTime = function (xPos, seconds) {
    xPos = Math.round(xPos);
    this._scrubJulian = JulianDate.addSeconds(
      this._startJulian,
      seconds,
      new JulianDate()
    );
    if (this._scrubElement) {
      var scrubX = xPos - 8;
      this._scrubElement.style.left = scrubX.toString() + "px";
      this._needleEle.style.left = xPos.toString() + "px";
    }

    var evt = document.createEvent("Event");
    evt.initEvent("settime", true, true);
    evt.clientX = xPos;
    evt.timeSeconds = seconds;
    evt.timeJulian = this._scrubJulian;
    evt.clock = this._clock;
    this._topDiv.dispatchEvent(evt);
  };

  function createMouseDownCallback(timeline) {
    return function (e) {
      if (timeline._mouseMode !== timelineMouseMode.touchOnly) {
        if (e.button === 0) {
          timeline._mouseMode = timelineMouseMode.scrub;
          if (timeline._scrubElement) {
            timeline._scrubElement.style.backgroundPosition = "-16px 0";
          }
          timeline._onMouseMove(e);
        } else {
          timeline._mouseX = e.clientX;
          if (e.button === 2) {
            timeline._mouseMode = timelineMouseMode.zoom;
          } else {
            timeline._mouseMode = timelineMouseMode.slide;
          }
        }
      }
      e.preventDefault();
    };
  }

  function createMouseUpCallback(timeline) {
    return function (e) {
      timeline._mouseMode = timelineMouseMode.none;
      if (timeline._scrubElement) {
        timeline._scrubElement.style.backgroundPosition = "0 0";
      }
      timeline._timelineDrag = 0;
      timeline._timelineDragLocation = undefined;
    };
  }

  function createMouseMoveCallback(timeline) {
    return function (e) {
      var dx;
      if (timeline._mouseMode === timelineMouseMode.scrub) {
        e.preventDefault();
        var x = e.clientX - timeline._topDiv.getBoundingClientRect().left;

        if (x < 0) {
          timeline._timelineDragLocation = 0;
          timeline._timelineDrag = -0.01 * timeline._timeBarSecondsSpan;
        } else if (x > timeline._topDiv.clientWidth) {
          timeline._timelineDragLocation = timeline._topDiv.clientWidth;
          timeline._timelineDrag = 0.01 * timeline._timeBarSecondsSpan;
        } else {
          timeline._timelineDragLocation = undefined;
          timeline._setTimeBarTime(
            x,
            (x * timeline._timeBarSecondsSpan) / timeline._topDiv.clientWidth
          );
        }
      } else if (timeline._mouseMode === timelineMouseMode.slide) {
        dx = timeline._mouseX - e.clientX;
        timeline._mouseX = e.clientX;
        if (dx !== 0) {
          var dsec =
            (dx * timeline._timeBarSecondsSpan) / timeline._topDiv.clientWidth;
          timeline.zoomTo(
            JulianDate.addSeconds(timeline._startJulian, dsec, new JulianDate()),
            JulianDate.addSeconds(timeline._endJulian, dsec, new JulianDate())
          );
        }
      } else if (timeline._mouseMode === timelineMouseMode.zoom) {
        dx = timeline._mouseX - e.clientX;
        timeline._mouseX = e.clientX;
        if (dx !== 0) {
          timeline.zoomFrom(Math.pow(1.01, dx));
        }
      }
    };
  }

  function createMouseWheelCallback(timeline) {
    return function (e) {
      var dy = e.wheelDeltaY || e.wheelDelta || -e.detail;
      timelineWheelDelta = Math.max(
        Math.min(Math.abs(dy), timelineWheelDelta),
        1
      );
      dy /= timelineWheelDelta;
      timeline.zoomFrom(Math.pow(1.05, -dy));
    };
  }

  function createTouchStartCallback(timeline) {
    return function (e) {
      var len = e.touches.length,
        seconds,
        xPos,
        leftX = timeline._topDiv.getBoundingClientRect().left;
      e.preventDefault();
      timeline._mouseMode = timelineMouseMode.touchOnly;
      if (len === 1) {
        seconds = JulianDate.secondsDifference(
          timeline._scrubJulian,
          timeline._startJulian
        );
        xPos = Math.round(
          (seconds * timeline._topDiv.clientWidth) /
            timeline._timeBarSecondsSpan +
            leftX
        );
        if (Math.abs(e.touches[0].clientX - xPos) < 50) {
          timeline._touchMode = timelineTouchMode.scrub;
          if (timeline._scrubElement) {
            timeline._scrubElement.style.backgroundPosition =
              len === 1 ? "-16px 0" : "0 0";
          }
        } else {
          timeline._touchMode = timelineTouchMode.singleTap;
          timeline._touchState.centerX = e.touches[0].clientX - leftX;
        }
      } else if (len === 2) {
        timeline._touchMode = timelineTouchMode.slideZoom;
        timeline._touchState.centerX =
          (e.touches[0].clientX + e.touches[1].clientX) * 0.5 - leftX;
        timeline._touchState.spanX = Math.abs(
          e.touches[0].clientX - e.touches[1].clientX
        );
      } else {
        timeline._touchMode = timelineTouchMode.ignore;
      }
    };
  }

  function createTouchEndCallback(timeline) {
    return function (e) {
      var len = e.touches.length,
        leftX = timeline._topDiv.getBoundingClientRect().left;
      if (timeline._touchMode === timelineTouchMode.singleTap) {
        timeline._touchMode = timelineTouchMode.scrub;
        timeline._onTouchMove(e);
      } else if (timeline._touchMode === timelineTouchMode.scrub) {
        timeline._onTouchMove(e);
      }
      timeline._mouseMode = timelineMouseMode.touchOnly;
      if (len !== 1) {
        timeline._touchMode =
          len > 0 ? timelineTouchMode.ignore : timelineTouchMode.none;
      } else if (timeline._touchMode === timelineTouchMode.slideZoom) {
        timeline._touchState.centerX = e.touches[0].clientX - leftX;
      }
      if (timeline._scrubElement) {
        timeline._scrubElement.style.backgroundPosition = "0 0";
      }
    };
  }

  function createTouchMoveCallback(timeline) {
    return function (e) {
      var dx,
        x,
        len,
        newCenter,
        newSpan,
        newStartTime,
        zoom = 1,
        leftX = timeline._topDiv.getBoundingClientRect().left;
      if (timeline._touchMode === timelineTouchMode.singleTap) {
        timeline._touchMode = timelineTouchMode.slideZoom;
      }
      timeline._mouseMode = timelineMouseMode.touchOnly;
      if (timeline._touchMode === timelineTouchMode.scrub) {
        e.preventDefault();
        if (e.changedTouches.length === 1) {
          x = e.changedTouches[0].clientX - leftX;
          if (x >= 0 && x <= timeline._topDiv.clientWidth) {
            timeline._setTimeBarTime(
              x,
              (x * timeline._timeBarSecondsSpan) / timeline._topDiv.clientWidth
            );
          }
        }
      } else if (timeline._touchMode === timelineTouchMode.slideZoom) {
        len = e.touches.length;
        if (len === 2) {
          newCenter = (e.touches[0].clientX + e.touches[1].clientX) * 0.5 - leftX;
          newSpan = Math.abs(e.touches[0].clientX - e.touches[1].clientX);
        } else if (len === 1) {
          newCenter = e.touches[0].clientX - leftX;
          newSpan = 0;
        }

        if (defined(newCenter)) {
          if (newSpan > 0 && timeline._touchState.spanX > 0) {
            // Zoom and slide
            zoom = timeline._touchState.spanX / newSpan;
            newStartTime = JulianDate.addSeconds(
              timeline._startJulian,
              (timeline._touchState.centerX * timeline._timeBarSecondsSpan -
                newCenter * timeline._timeBarSecondsSpan * zoom) /
                timeline._topDiv.clientWidth,
              new JulianDate()
            );
          } else {
            // Slide to newCenter
            dx = timeline._touchState.centerX - newCenter;
            newStartTime = JulianDate.addSeconds(
              timeline._startJulian,
              (dx * timeline._timeBarSecondsSpan) / timeline._topDiv.clientWidth,
              new JulianDate()
            );
          }

          timeline.zoomTo(
            newStartTime,
            JulianDate.addSeconds(
              newStartTime,
              timeline._timeBarSecondsSpan * zoom,
              new JulianDate()
            )
          );
          timeline._touchState.centerX = newCenter;
          timeline._touchState.spanX = newSpan;
        }
      }
    };
  }

  /**
   * Resizes the widget to match the container size.
   */
  Timeline.prototype.resize = function () {
    var width = this.container.clientWidth;
    var height = this.container.clientHeight;

    if (width === this._lastWidth && height === this._lastHeight) {
      return;
    }

    this._trackContainer.style.height = height + "px";

    var trackListHeight = 1;
    this._trackList.forEach(function (track) {
      trackListHeight += track.height;
    });
    this._trackListEle.style.height = trackListHeight.toString() + "px";
    this._trackListEle.width = this._trackListEle.clientWidth;
    this._trackListEle.height = trackListHeight;
    this._makeTics();

    this._lastXPos = undefined;
    this._lastWidth = width;
    this._lastHeight = height;
  };

  function lockScreen(orientation) {
    var locked = false;
    var screen = window.screen;
    if (defined(screen)) {
      if (defined(screen.lockOrientation)) {
        locked = screen.lockOrientation(orientation);
      } else if (defined(screen.mozLockOrientation)) {
        locked = screen.mozLockOrientation(orientation);
      } else if (defined(screen.msLockOrientation)) {
        locked = screen.msLockOrientation(orientation);
      } else if (defined(screen.orientation && screen.orientation.lock)) {
        locked = screen.orientation.lock(orientation);
      }
    }
    return locked;
  }

  function unlockScreen() {
    var screen = window.screen;
    if (defined(screen)) {
      if (defined(screen.unlockOrientation)) {
        screen.unlockOrientation();
      } else if (defined(screen.mozUnlockOrientation)) {
        screen.mozUnlockOrientation();
      } else if (defined(screen.msUnlockOrientation)) {
        screen.msUnlockOrientation();
      } else if (defined(screen.orientation && screen.orientation.unlock)) {
        screen.orientation.unlock();
      }
    }
  }

  function toggleVR(viewModel, scene, isVRMode, isOrthographic) {
    if (isOrthographic()) {
      return;
    }

    if (isVRMode()) {
      scene.useWebVR = false;
      if (viewModel._locked) {
        unlockScreen();
        viewModel._locked = false;
      }
      viewModel._noSleep.disable();
      Fullscreen.exitFullscreen();
      isVRMode(false);
    } else {
      if (!Fullscreen.fullscreen) {
        Fullscreen.requestFullscreen(viewModel._vrElement);
      }
      viewModel._noSleep.enable();
      if (!viewModel._locked) {
        viewModel._locked = lockScreen("landscape");
      }
      scene.useWebVR = true;
      isVRMode(true);
    }
  }

  /**
   * The view model for {@link VRButton}.
   * @alias VRButtonViewModel
   * @constructor
   *
   * @param {Scene} scene The scene.
   * @param {Element|String} [vrElement=document.body] The element or id to be placed into VR mode.
   */
  function VRButtonViewModel(scene, vrElement) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    var that = this;

    var isEnabled = knockout.observable(Fullscreen.enabled);
    var isVRMode = knockout.observable(false);

    /**
     * Gets whether or not VR mode is active.
     *
     * @type {Boolean}
     */
    this.isVRMode = undefined;
    knockout.defineProperty(this, "isVRMode", {
      get: function () {
        return isVRMode();
      },
    });

    /**
     * Gets or sets whether or not VR functionality should be enabled.
     *
     * @type {Boolean}
     * @see Fullscreen.enabled
     */
    this.isVREnabled = undefined;
    knockout.defineProperty(this, "isVREnabled", {
      get: function () {
        return isEnabled();
      },
      set: function (value) {
        isEnabled(value && Fullscreen.enabled);
      },
    });

    /**
     * Gets the tooltip.  This property is observable.
     *
     * @type {String}
     */
    this.tooltip = undefined;
    knockout.defineProperty(this, "tooltip", function () {
      if (!isEnabled()) {
        return "VR mode is unavailable";
      }
      return isVRMode() ? "Exit VR mode" : "Enter VR mode";
    });

    var isOrthographic = knockout.observable(false);

    this._isOrthographic = undefined;
    knockout.defineProperty(this, "_isOrthographic", {
      get: function () {
        return isOrthographic();
      },
    });

    this._eventHelper = new EventHelper();
    this._eventHelper.add(scene.preRender, function () {
      isOrthographic(scene.camera.frustum instanceof OrthographicFrustum);
    });

    this._locked = false;
    this._noSleep = new NoSleep();

    this._command = createCommand$2(function () {
      toggleVR(that, scene, isVRMode, isOrthographic);
    }, knockout.getObservable(this, "isVREnabled"));

    this._vrElement = defaultValue(getElement(vrElement), document.body);

    this._callback = function () {
      if (!Fullscreen.fullscreen && isVRMode()) {
        scene.useWebVR = false;
        if (that._locked) {
          unlockScreen();
          that._locked = false;
        }
        that._noSleep.disable();
        isVRMode(false);
      }
    };
    document.addEventListener(Fullscreen.changeEventName, this._callback);
  }

  Object.defineProperties(VRButtonViewModel.prototype, {
    /**
     * Gets or sets the HTML element to place into VR mode when the
     * corresponding button is pressed.
     * @memberof VRButtonViewModel.prototype
     *
     * @type {Element}
     */
    vrElement: {
      //TODO:@exception {DeveloperError} value must be a valid HTML Element.
      get: function () {
        return this._vrElement;
      },
      set: function (value) {
        //>>includeStart('debug', pragmas.debug);
        if (!(value instanceof Element)) {
          throw new DeveloperError("value must be a valid Element.");
        }
        //>>includeEnd('debug');

        this._vrElement = value;
      },
    },

    /**
     * Gets the Command to toggle VR mode.
     * @memberof VRButtonViewModel.prototype
     *
     * @type {Command}
     */
    command: {
      get: function () {
        return this._command;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  VRButtonViewModel.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the view model.  Should be called to
   * properly clean up the view model when it is no longer needed.
   */
  VRButtonViewModel.prototype.destroy = function () {
    this._eventHelper.removeAll();
    document.removeEventListener(Fullscreen.changeEventName, this._callback);
    destroyObject(this);
  };

  var enterVRPath =
    "M 5.3125 6.375 C 4.008126 6.375 2.96875 7.4141499 2.96875 8.71875 L 2.96875 19.5 C 2.96875 20.8043 4.008126 21.875 5.3125 21.875 L 13.65625 21.875 C 13.71832 20.0547 14.845166 18.59375 16.21875 18.59375 C 17.592088 18.59375 18.71881 20.0552 18.78125 21.875 L 27.09375 21.875 C 28.398125 21.875 29.4375 20.8043 29.4375 19.5 L 29.4375 8.71875 C 29.4375 7.4141499 28.398125 6.375 27.09375 6.375 L 5.3125 6.375 z M 9.625 10.4375 C 11.55989 10.4375 13.125 12.03385 13.125 13.96875 C 13.125 15.90365 11.55989 17.46875 9.625 17.46875 C 7.69011 17.46875 6.125 15.90365 6.125 13.96875 C 6.125 12.03385 7.69011 10.4375 9.625 10.4375 z M 22.46875 10.4375 C 24.40364 10.4375 25.96875 12.03385 25.96875 13.96875 C 25.96875 15.90365 24.40364 17.46875 22.46875 17.46875 C 20.53386 17.46875 18.96875 15.90365 18.96875 13.96875 C 18.96875 12.03385 20.53386 10.4375 22.46875 10.4375 z";
  var exitVRPath =
    "M 25.770585,2.4552065 C 15.72282,13.962707 10.699956,19.704407 8.1768352,22.580207 c -1.261561,1.4379 -1.902282,2.1427 -2.21875,2.5 -0.141624,0.1599 -0.208984,0.2355 -0.25,0.2813 l 0.6875,0.75 c 10e-5,-10e-5 0.679191,0.727 0.6875,0.7187 0.01662,-0.016 0.02451,-0.024 0.03125,-0.031 0.01348,-0.014 0.04013,-0.038 0.0625,-0.062 0.04474,-0.05 0.120921,-0.1315 0.28125,-0.3126 0.320657,-0.3619 0.956139,-1.0921 2.2187499,-2.5312 2.5252219,-2.8781 7.5454589,-8.6169 17.5937499,-20.1250005 l -1.5,-1.3125 z m -20.5624998,3.9063 c -1.304375,0 -2.34375,1.0391 -2.34375,2.3437 l 0,10.8125005 c 0,1.3043 1.039375,2.375 2.34375,2.375 l 2.25,0 c 1.9518039,-2.2246 7.4710958,-8.5584 13.5624998,-15.5312005 l -15.8124998,0 z m 21.1249998,0 c -1.855467,2.1245 -2.114296,2.4005 -3.59375,4.0936995 1.767282,0.1815 3.15625,1.685301 3.15625,3.500001 0,1.9349 -1.56511,3.5 -3.5,3.5 -1.658043,0 -3.043426,-1.1411 -3.40625,-2.6875 -1.089617,1.2461 -2.647139,2.9988 -3.46875,3.9375 0.191501,-0.062 0.388502,-0.094 0.59375,-0.094 1.373338,0 2.50006,1.4614 2.5625,3.2812 l 8.3125,0 c 1.304375,0 2.34375,-1.0707 2.34375,-2.375 l 0,-10.8125005 c 0,-1.3046 -1.039375,-2.3437 -2.34375,-2.3437 l -0.65625,0 z M 9.5518351,10.423906 c 1.9348899,0 3.4999999,1.596401 3.4999999,3.531301 0,1.9349 -1.56511,3.5 -3.4999999,3.5 -1.9348899,0 -3.4999999,-1.5651 -3.4999999,-3.5 0,-1.9349 1.56511,-3.531301 3.4999999,-3.531301 z m 4.2187499,10.312601 c -0.206517,0.2356 -0.844218,0.9428 -1.03125,1.1562 l 0.8125,0 c 0.01392,-0.4081 0.107026,-0.7968 0.21875,-1.1562 z";

  /**
   * A single button widget for toggling vr mode.
   *
   * @alias VRButton
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Scene} scene The scene.
   * @param {Element|String} [vrElement=document.body] The element or id to be placed into vr mode.
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   */
  function VRButton(container, scene, vrElement) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    if (!defined(scene)) {
      throw new DeveloperError("scene is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);

    var viewModel = new VRButtonViewModel(scene, vrElement);

    viewModel._exitVRPath = exitVRPath;
    viewModel._enterVRPath = enterVRPath;

    var element = document.createElement("button");
    element.type = "button";
    element.className = "cesium-button cesium-vrButton";
    element.setAttribute(
      "data-bind",
      '\
css: { "cesium-button-disabled" : _isOrthographic }, \
attr: { title: tooltip },\
click: command,\
enable: isVREnabled,\
cesiumSvgPath: { path: isVRMode ? _exitVRPath : _enterVRPath, width: 32, height: 32 }'
    );

    container.appendChild(element);

    knockout.applyBindings(viewModel, element);

    this._container = container;
    this._viewModel = viewModel;
    this._element = element;
  }

  Object.defineProperties(VRButton.prototype, {
    /**
     * Gets the parent container.
     * @memberof VRButton.prototype
     *
     * @type {Element}
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the view model.
     * @memberof VRButton.prototype
     *
     * @type {VRButtonViewModel}
     */
    viewModel: {
      get: function () {
        return this._viewModel;
      },
    },
  });

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  VRButton.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  VRButton.prototype.destroy = function () {
    this._viewModel.destroy();

    knockout.cleanNode(this._element);
    this._container.removeChild(this._element);

    return destroyObject(this);
  };

  var boundingSphereScratch$2 = new BoundingSphere();

  function onTimelineScrubfunction(e) {
    var clock = e.clock;
    clock.currentTime = e.timeJulian;
    clock.shouldAnimate = false;
  }

  function pickEntity(viewer, e) {
    var picked = viewer.scene.pick(e.position);
    if (defined(picked)) {
      var id = defaultValue(picked.id, picked.primitive.id);
      if (id instanceof Entity) {
        return id;
      }
    }

    // No regular entity picked.  Try picking features from imagery layers.
    if (defined(viewer.scene.globe)) {
      return pickImageryLayerFeature(viewer, e.position);
    }
  }

  function trackDataSourceClock(timeline, clock, dataSource) {
    if (defined(dataSource)) {
      var dataSourceClock = dataSource.clock;
      if (defined(dataSourceClock)) {
        dataSourceClock.getValue(clock);
        if (defined(timeline)) {
          timeline.updateFromClock();
          timeline.zoomTo(dataSourceClock.startTime, dataSourceClock.stopTime);
        }
      }
    }
  }

  var cartesian3Scratch$3 = new Cartesian3();

  function pickImageryLayerFeature(viewer, windowPosition) {
    var scene = viewer.scene;
    var pickRay = scene.camera.getPickRay(windowPosition);
    var imageryLayerFeaturePromise = scene.imageryLayers.pickImageryLayerFeatures(
      pickRay,
      scene
    );
    if (!defined(imageryLayerFeaturePromise)) {
      return;
    }

    // Imagery layer feature picking is asynchronous, so put up a message while loading.
    var loadingMessage = new Entity({
      id: "Loading...",
      description: "Loading feature information...",
    });

    when(
      imageryLayerFeaturePromise,
      function (features) {
        // Has this async pick been superseded by a later one?
        if (viewer.selectedEntity !== loadingMessage) {
          return;
        }

        if (!defined(features) || features.length === 0) {
          viewer.selectedEntity = createNoFeaturesEntity();
          return;
        }

        // Select the first feature.
        var feature = features[0];

        var entity = new Entity({
          id: feature.name,
          description: feature.description,
        });

        if (defined(feature.position)) {
          var ecfPosition = viewer.scene.globe.ellipsoid.cartographicToCartesian(
            feature.position,
            cartesian3Scratch$3
          );
          entity.position = new ConstantPositionProperty(ecfPosition);
        }

        viewer.selectedEntity = entity;
      },
      function () {
        // Has this async pick been superseded by a later one?
        if (viewer.selectedEntity !== loadingMessage) {
          return;
        }
        viewer.selectedEntity = createNoFeaturesEntity();
      }
    );

    return loadingMessage;
  }

  function createNoFeaturesEntity() {
    return new Entity({
      id: "None",
      description: "No features found.",
    });
  }

  function enableVRUI(viewer, enabled) {
    var geocoder = viewer._geocoder;
    var homeButton = viewer._homeButton;
    var sceneModePicker = viewer._sceneModePicker;
    var projectionPicker = viewer._projectionPicker;
    var baseLayerPicker = viewer._baseLayerPicker;
    var animation = viewer._animation;
    var timeline = viewer._timeline;
    var fullscreenButton = viewer._fullscreenButton;
    var infoBox = viewer._infoBox;
    var selectionIndicator = viewer._selectionIndicator;

    var visibility = enabled ? "hidden" : "visible";

    if (defined(geocoder)) {
      geocoder.container.style.visibility = visibility;
    }
    if (defined(homeButton)) {
      homeButton.container.style.visibility = visibility;
    }
    if (defined(sceneModePicker)) {
      sceneModePicker.container.style.visibility = visibility;
    }
    if (defined(projectionPicker)) {
      projectionPicker.container.style.visibility = visibility;
    }
    if (defined(baseLayerPicker)) {
      baseLayerPicker.container.style.visibility = visibility;
    }
    if (defined(animation)) {
      animation.container.style.visibility = visibility;
    }
    if (defined(timeline)) {
      timeline.container.style.visibility = visibility;
    }
    if (
      defined(fullscreenButton) &&
      fullscreenButton.viewModel.isFullscreenEnabled
    ) {
      fullscreenButton.container.style.visibility = visibility;
    }
    if (defined(infoBox)) {
      infoBox.container.style.visibility = visibility;
    }
    if (defined(selectionIndicator)) {
      selectionIndicator.container.style.visibility = visibility;
    }

    if (viewer._container) {
      var right =
        enabled || !defined(fullscreenButton)
          ? 0
          : fullscreenButton.container.clientWidth;
      viewer._vrButton.container.style.right = right + "px";

      viewer.forceResize();
    }
  }

  /**
   * @typedef {Object} Viewer.ConstructorOptions
   *
   * Initialization options for the Viewer constructor
   *
   * @property {Boolean} [animation=true] If set to false, the Animation widget will not be created.
   * @property {Boolean} [baseLayerPicker=true] If set to false, the BaseLayerPicker widget will not be created.
   * @property {Boolean} [fullscreenButton=true] If set to false, the FullscreenButton widget will not be created.
   * @property {Boolean} [vrButton=false] If set to true, the VRButton widget will be created.
   * @property {Boolean|GeocoderService[]} [geocoder=true] If set to false, the Geocoder widget will not be created.
   * @property {Boolean} [homeButton=true] If set to false, the HomeButton widget will not be created.
   * @property {Boolean} [infoBox=true] If set to false, the InfoBox widget will not be created.
   * @property {Boolean} [sceneModePicker=true] If set to false, the SceneModePicker widget will not be created.
   * @property {Boolean} [selectionIndicator=true] If set to false, the SelectionIndicator widget will not be created.
   * @property {Boolean} [timeline=true] If set to false, the Timeline widget will not be created.
   * @property {Boolean} [navigationHelpButton=true] If set to false, the navigation help button will not be created.
   * @property {Boolean} [navigationInstructionsInitiallyVisible=true] True if the navigation instructions should initially be visible, or false if the should not be shown until the user explicitly clicks the button.
   * @property {Boolean} [scene3DOnly=false] When <code>true</code>, each geometry instance will only be rendered in 3D to save GPU memory.
   * @property {Boolean} [shouldAnimate=false] <code>true</code> if the clock should attempt to advance simulation time by default, <code>false</code> otherwise.  This option takes precedence over setting {@link Viewer#clockViewModel}.
   * @property {ClockViewModel} [clockViewModel=new ClockViewModel(clock)] The clock view model to use to control current time.
   * @property {ProviderViewModel} [selectedImageryProviderViewModel] The view model for the current base imagery layer, if not supplied the first available base layer is used.  This value is only valid if `baseLayerPicker` is set to true.
   * @property {ProviderViewModel[]} [imageryProviderViewModels=createDefaultImageryProviderViewModels()] The array of ProviderViewModels to be selectable from the BaseLayerPicker.  This value is only valid if `baseLayerPicker` is set to true.
   * @property {ProviderViewModel} [selectedTerrainProviderViewModel] The view model for the current base terrain layer, if not supplied the first available base layer is used.  This value is only valid if `baseLayerPicker` is set to true.
   * @property {ProviderViewModel[]} [terrainProviderViewModels=createDefaultTerrainProviderViewModels()] The array of ProviderViewModels to be selectable from the BaseLayerPicker.  This value is only valid if `baseLayerPicker` is set to true.
   * @property {ImageryProvider} [imageryProvider=createWorldImagery()] The imagery provider to use.  This value is only valid if `baseLayerPicker` is set to false.
   * @property {TerrainProvider} [terrainProvider=new EllipsoidTerrainProvider()] The terrain provider to use
   * @property {SkyBox|false} [skyBox] The skybox used to render the stars.  When <code>undefined</code>, the default stars are used. If set to <code>false</code>, no skyBox, Sun, or Moon will be added.
   * @property {SkyAtmosphere|false} [skyAtmosphere] Blue sky, and the glow around the Earth's limb.  Set to <code>false</code> to turn it off.
   * @property {Element|String} [fullscreenElement=document.body] The element or id to be placed into fullscreen mode when the full screen button is pressed.
   * @property {Boolean} [useDefaultRenderLoop=true] True if this widget should control the render loop, false otherwise.
   * @property {Number} [targetFrameRate] The target frame rate when using the default render loop.
   * @property {Boolean} [showRenderLoopErrors=true] If true, this widget will automatically display an HTML panel to the user containing the error, if a render loop error occurs.
   * @property {Boolean} [useBrowserRecommendedResolution=true] If true, render at the browser's recommended resolution and ignore <code>window.devicePixelRatio</code>.
   * @property {Boolean} [automaticallyTrackDataSourceClocks=true] If true, this widget will automatically track the clock settings of newly added DataSources, updating if the DataSource's clock changes.  Set this to false if you want to configure the clock independently.
   * @property {Object} [contextOptions] Context and WebGL creation properties corresponding to <code>options</code> passed to {@link Scene}.
   * @property {SceneMode} [sceneMode=SceneMode.SCENE3D] The initial scene mode.
   * @property {MapProjection} [mapProjection=new GeographicProjection()] The map projection to use in 2D and Columbus View modes.
   * @property {Globe} [globe=new Globe(mapProjection.ellipsoid)] The globe to use in the scene.  If set to <code>false</code>, no globe will be added.
   * @property {Boolean} [orderIndependentTranslucency=true] If true and the configuration supports it, use order independent translucency.
   * @property {Element|String} [creditContainer] The DOM element or ID that will contain the {@link CreditDisplay}.  If not specified, the credits are added to the bottom of the widget itself.
   * @property {Element|String} [creditViewport] The DOM element or ID that will contain the credit pop up created by the {@link CreditDisplay}.  If not specified, it will appear over the widget itself.
   * @property {DataSourceCollection} [dataSources=new DataSourceCollection()] The collection of data sources visualized by the widget.  If this parameter is provided,
   *                               the instance is assumed to be owned by the caller and will not be destroyed when the viewer is destroyed.
   * @property {Number} [terrainExaggeration=1.0] A scalar used to exaggerate the terrain. Note that terrain exaggeration will not modify any other primitive as they are positioned relative to the ellipsoid.
   * @property {Boolean} [shadows=false] Determines if shadows are cast by light sources.
   * @property {ShadowMode} [terrainShadows=ShadowMode.RECEIVE_ONLY] Determines if the terrain casts or receives shadows from light sources.
   * @property {MapMode2D} [mapMode2D=MapMode2D.INFINITE_SCROLL] Determines if the 2D map is rotatable or can be scrolled infinitely in the horizontal direction.
   * @property {Boolean} [projectionPicker=false] If set to true, the ProjectionPicker widget will be created.
   * @property {Boolean} [requestRenderMode=false] If true, rendering a frame will only occur when needed as determined by changes within the scene. Enabling reduces the CPU/GPU usage of your application and uses less battery on mobile, but requires using {@link Scene#requestRender} to render a new frame explicitly in this mode. This will be necessary in many cases after making changes to the scene in other parts of the API. See {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}.
   * @property {Number} [maximumRenderTimeChange=0.0] If requestRenderMode is true, this value defines the maximum change in simulation time allowed before a render is requested. See {@link https://cesium.com/blog/2018/01/24/cesium-scene-rendering-performance/|Improving Performance with Explicit Rendering}.
   */

  /**
   * A base widget for building applications.  It composites all of the standard Cesium widgets into one reusable package.
   * The widget can always be extended by using mixins, which add functionality useful for a variety of applications.
   *
   * @alias Viewer
   * @constructor
   *
   * @param {Element|String} container The DOM element or ID that will contain the widget.
   * @param {Viewer.ConstructorOptions} [options] Object describing initialization options
   *
   * @exception {DeveloperError} Element with id "container" does not exist in the document.
   * @exception {DeveloperError} options.selectedImageryProviderViewModel is not available when not using the BaseLayerPicker widget, specify options.imageryProvider instead.
   * @exception {DeveloperError} options.selectedTerrainProviderViewModel is not available when not using the BaseLayerPicker widget, specify options.terrainProvider instead.
   *
   * @see Animation
   * @see BaseLayerPicker
   * @see CesiumWidget
   * @see FullscreenButton
   * @see HomeButton
   * @see SceneModePicker
   * @see Timeline
   * @see viewerDragDropMixin
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Hello%20World.html|Cesium Sandcastle Hello World Demo}
   *
   * @example
   * //Initialize the viewer widget with several custom options and mixins.
   * var viewer = new Cesium.Viewer('cesiumContainer', {
   *     //Start in Columbus Viewer
   *     sceneMode : Cesium.SceneMode.COLUMBUS_VIEW,
   *     //Use Cesium World Terrain
   *     terrainProvider : Cesium.createWorldTerrain(),
   *     //Hide the base layer picker
   *     baseLayerPicker : false,
   *     //Use OpenStreetMaps
   *     imageryProvider : new Cesium.OpenStreetMapImageryProvider({
   *         url : 'https://a.tile.openstreetmap.org/'
   *     }),
   *     skyBox : new Cesium.SkyBox({
   *         sources : {
   *           positiveX : 'stars/TychoSkymapII.t3_08192x04096_80_px.jpg',
   *           negativeX : 'stars/TychoSkymapII.t3_08192x04096_80_mx.jpg',
   *           positiveY : 'stars/TychoSkymapII.t3_08192x04096_80_py.jpg',
   *           negativeY : 'stars/TychoSkymapII.t3_08192x04096_80_my.jpg',
   *           positiveZ : 'stars/TychoSkymapII.t3_08192x04096_80_pz.jpg',
   *           negativeZ : 'stars/TychoSkymapII.t3_08192x04096_80_mz.jpg'
   *         }
   *     }),
   *     // Show Columbus View map with Web Mercator projection
   *     mapProjection : new Cesium.WebMercatorProjection()
   * });
   *
   * //Add basic drag and drop functionality
   * viewer.extend(Cesium.viewerDragDropMixin);
   *
   * //Show a pop-up alert if we encounter an error when processing a dropped file
   * viewer.dropError.addEventListener(function(dropHandler, name, error) {
   *     console.log(error);
   *     window.alert(error);
   * });
   */
  function Viewer(container, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(container)) {
      throw new DeveloperError("container is required.");
    }
    //>>includeEnd('debug');

    container = getElement(container);
    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var createBaseLayerPicker =
      (!defined(options.globe) || options.globe !== false) &&
      (!defined(options.baseLayerPicker) || options.baseLayerPicker !== false);

    //>>includeStart('debug', pragmas.debug);
    // If not using BaseLayerPicker, selectedImageryProviderViewModel is an invalid option
    if (
      !createBaseLayerPicker &&
      defined(options.selectedImageryProviderViewModel)
    ) {
      throw new DeveloperError(
        "options.selectedImageryProviderViewModel is not available when not using the BaseLayerPicker widget. \
Either specify options.imageryProvider instead or set options.baseLayerPicker to true."
      );
    }

    // If not using BaseLayerPicker, selectedTerrainProviderViewModel is an invalid option
    if (
      !createBaseLayerPicker &&
      defined(options.selectedTerrainProviderViewModel)
    ) {
      throw new DeveloperError(
        "options.selectedTerrainProviderViewModel is not available when not using the BaseLayerPicker widget. \
Either specify options.terrainProvider instead or set options.baseLayerPicker to true."
      );
    }
    //>>includeEnd('debug')

    var that = this;

    var viewerContainer = document.createElement("div");
    viewerContainer.className = "cesium-viewer";
    container.appendChild(viewerContainer);

    // Cesium widget container
    var cesiumWidgetContainer = document.createElement("div");
    cesiumWidgetContainer.className = "cesium-viewer-cesiumWidgetContainer";
    viewerContainer.appendChild(cesiumWidgetContainer);

    // Bottom container
    var bottomContainer = document.createElement("div");
    bottomContainer.className = "cesium-viewer-bottom";

    viewerContainer.appendChild(bottomContainer);

    var scene3DOnly = defaultValue(options.scene3DOnly, false);

    var clock;
    var clockViewModel;
    var destroyClockViewModel = false;
    if (defined(options.clockViewModel)) {
      clockViewModel = options.clockViewModel;
      clock = clockViewModel.clock;
    } else {
      clock = new Clock();
      clockViewModel = new ClockViewModel(clock);
      destroyClockViewModel = true;
    }

    if (defined(options.shouldAnimate)) {
      clock.shouldAnimate = options.shouldAnimate;
    }

    // Cesium widget
    var cesiumWidget = new CesiumWidget(cesiumWidgetContainer, {
      imageryProvider:
        createBaseLayerPicker || defined(options.imageryProvider)
          ? false
          : undefined,
      clock: clock,
      skyBox: options.skyBox,
      skyAtmosphere: options.skyAtmosphere,
      sceneMode: options.sceneMode,
      mapProjection: options.mapProjection,
      globe: options.globe,
      orderIndependentTranslucency: options.orderIndependentTranslucency,
      contextOptions: options.contextOptions,
      useDefaultRenderLoop: options.useDefaultRenderLoop,
      targetFrameRate: options.targetFrameRate,
      showRenderLoopErrors: options.showRenderLoopErrors,
      useBrowserRecommendedResolution: options.useBrowserRecommendedResolution,
      creditContainer: defined(options.creditContainer)
        ? options.creditContainer
        : bottomContainer,
      creditViewport: options.creditViewport,
      scene3DOnly: scene3DOnly,
      terrainExaggeration: options.terrainExaggeration,
      shadows: options.shadows,
      terrainShadows: options.terrainShadows,
      mapMode2D: options.mapMode2D,
      requestRenderMode: options.requestRenderMode,
      maximumRenderTimeChange: options.maximumRenderTimeChange,
    });

    var dataSourceCollection = options.dataSources;
    var destroyDataSourceCollection = false;
    if (!defined(dataSourceCollection)) {
      dataSourceCollection = new DataSourceCollection();
      destroyDataSourceCollection = true;
    }

    var scene = cesiumWidget.scene;

    var dataSourceDisplay = new DataSourceDisplay({
      scene: scene,
      dataSourceCollection: dataSourceCollection,
    });

    var eventHelper = new EventHelper();

    eventHelper.add(clock.onTick, Viewer.prototype._onTick, this);
    eventHelper.add(scene.morphStart, Viewer.prototype._clearTrackedObject, this);

    // Selection Indicator
    var selectionIndicator;
    if (
      !defined(options.selectionIndicator) ||
      options.selectionIndicator !== false
    ) {
      var selectionIndicatorContainer = document.createElement("div");
      selectionIndicatorContainer.className =
        "cesium-viewer-selectionIndicatorContainer";
      viewerContainer.appendChild(selectionIndicatorContainer);
      selectionIndicator = new SelectionIndicator(
        selectionIndicatorContainer,
        scene
      );
    }

    // Info Box
    var infoBox;
    if (!defined(options.infoBox) || options.infoBox !== false) {
      var infoBoxContainer = document.createElement("div");
      infoBoxContainer.className = "cesium-viewer-infoBoxContainer";
      viewerContainer.appendChild(infoBoxContainer);
      infoBox = new InfoBox(infoBoxContainer);

      var infoBoxViewModel = infoBox.viewModel;
      eventHelper.add(
        infoBoxViewModel.cameraClicked,
        Viewer.prototype._onInfoBoxCameraClicked,
        this
      );
      eventHelper.add(
        infoBoxViewModel.closeClicked,
        Viewer.prototype._onInfoBoxClockClicked,
        this
      );
    }

    // Main Toolbar
    var toolbar = document.createElement("div");
    toolbar.className = "cesium-viewer-toolbar";
    viewerContainer.appendChild(toolbar);

    // Geocoder
    var geocoder;
    if (!defined(options.geocoder) || options.geocoder !== false) {
      var geocoderContainer = document.createElement("div");
      geocoderContainer.className = "cesium-viewer-geocoderContainer";
      toolbar.appendChild(geocoderContainer);
      var geocoderService;
      if (defined(options.geocoder) && typeof options.geocoder !== "boolean") {
        geocoderService = Array.isArray(options.geocoder)
          ? options.geocoder
          : [options.geocoder];
      }
      geocoder = new Geocoder({
        container: geocoderContainer,
        geocoderServices: geocoderService,
        scene: scene,
      });
      // Subscribe to search so that we can clear the trackedEntity when it is clicked.
      eventHelper.add(
        geocoder.viewModel.search.beforeExecute,
        Viewer.prototype._clearObjects,
        this
      );
    }

    // HomeButton
    var homeButton;
    if (!defined(options.homeButton) || options.homeButton !== false) {
      homeButton = new HomeButton(toolbar, scene);
      if (defined(geocoder)) {
        eventHelper.add(homeButton.viewModel.command.afterExecute, function () {
          var viewModel = geocoder.viewModel;
          viewModel.searchText = "";
          if (viewModel.isSearchInProgress) {
            viewModel.search();
          }
        });
      }
      // Subscribe to the home button beforeExecute event so that we can clear the trackedEntity.
      eventHelper.add(
        homeButton.viewModel.command.beforeExecute,
        Viewer.prototype._clearTrackedObject,
        this
      );
    }

    // SceneModePicker
    // By default, we silently disable the scene mode picker if scene3DOnly is true,
    // but if sceneModePicker is explicitly set to true, throw an error.
    //>>includeStart('debug', pragmas.debug);
    if (options.sceneModePicker === true && scene3DOnly) {
      throw new DeveloperError(
        "options.sceneModePicker is not available when options.scene3DOnly is set to true."
      );
    }
    //>>includeEnd('debug');

    var sceneModePicker;
    if (
      !scene3DOnly &&
      (!defined(options.sceneModePicker) || options.sceneModePicker !== false)
    ) {
      sceneModePicker = new SceneModePicker(toolbar, scene);
    }

    var projectionPicker;
    if (options.projectionPicker) {
      projectionPicker = new ProjectionPicker(toolbar, scene);
    }

    // BaseLayerPicker
    var baseLayerPicker;
    var baseLayerPickerDropDown;
    if (createBaseLayerPicker) {
      var imageryProviderViewModels = defaultValue(
        options.imageryProviderViewModels,
        createDefaultImageryProviderViewModels()
      );
      var terrainProviderViewModels = defaultValue(
        options.terrainProviderViewModels,
        createDefaultTerrainProviderViewModels()
      );

      baseLayerPicker = new BaseLayerPicker(toolbar, {
        globe: scene.globe,
        imageryProviderViewModels: imageryProviderViewModels,
        selectedImageryProviderViewModel:
          options.selectedImageryProviderViewModel,
        terrainProviderViewModels: terrainProviderViewModels,
        selectedTerrainProviderViewModel:
          options.selectedTerrainProviderViewModel,
      });

      //Grab the dropdown for resize code.
      var elements = toolbar.getElementsByClassName(
        "cesium-baseLayerPicker-dropDown"
      );
      baseLayerPickerDropDown = elements[0];
    }

    // These need to be set after the BaseLayerPicker is created in order to take effect
    if (defined(options.imageryProvider) && options.imageryProvider !== false) {
      if (createBaseLayerPicker) {
        baseLayerPicker.viewModel.selectedImagery = undefined;
      }
      scene.imageryLayers.removeAll();
      scene.imageryLayers.addImageryProvider(options.imageryProvider);
    }
    if (defined(options.terrainProvider)) {
      if (createBaseLayerPicker) {
        baseLayerPicker.viewModel.selectedTerrain = undefined;
      }
      scene.terrainProvider = options.terrainProvider;
    }

    // Navigation Help Button
    var navigationHelpButton;
    if (
      !defined(options.navigationHelpButton) ||
      options.navigationHelpButton !== false
    ) {
      var showNavHelp = true;
      try {
        //window.localStorage is null if disabled in Firefox or undefined in browsers with implementation
        if (defined(window.localStorage)) {
          var hasSeenNavHelp = window.localStorage.getItem(
            "cesium-hasSeenNavHelp"
          );
          if (defined(hasSeenNavHelp) && Boolean(hasSeenNavHelp)) {
            showNavHelp = false;
          } else {
            window.localStorage.setItem("cesium-hasSeenNavHelp", "true");
          }
        }
      } catch (e) {
        //Accessing window.localStorage throws if disabled in Chrome
        //window.localStorage.setItem throws if in Safari private browsing mode or in any browser if we are over quota.
      }
      navigationHelpButton = new NavigationHelpButton({
        container: toolbar,
        instructionsInitiallyVisible: defaultValue(
          options.navigationInstructionsInitiallyVisible,
          showNavHelp
        ),
      });
    }

    // Animation
    var animation;
    if (!defined(options.animation) || options.animation !== false) {
      var animationContainer = document.createElement("div");
      animationContainer.className = "cesium-viewer-animationContainer";
      viewerContainer.appendChild(animationContainer);
      animation = new Animation(
        animationContainer,
        new AnimationViewModel(clockViewModel)
      );
    }

    // Timeline
    var timeline;
    if (!defined(options.timeline) || options.timeline !== false) {
      var timelineContainer = document.createElement("div");
      timelineContainer.className = "cesium-viewer-timelineContainer";
      viewerContainer.appendChild(timelineContainer);
      timeline = new Timeline(timelineContainer, clock);
      timeline.addEventListener("settime", onTimelineScrubfunction, false);
      timeline.zoomTo(clock.startTime, clock.stopTime);
    }

    // Fullscreen
    var fullscreenButton;
    var fullscreenSubscription;
    var fullscreenContainer;
    if (
      !defined(options.fullscreenButton) ||
      options.fullscreenButton !== false
    ) {
      fullscreenContainer = document.createElement("div");
      fullscreenContainer.className = "cesium-viewer-fullscreenContainer";
      viewerContainer.appendChild(fullscreenContainer);
      fullscreenButton = new FullscreenButton(
        fullscreenContainer,
        options.fullscreenElement
      );

      //Subscribe to fullscreenButton.viewModel.isFullscreenEnabled so
      //that we can hide/show the button as well as size the timeline.
      fullscreenSubscription = subscribeAndEvaluate(
        fullscreenButton.viewModel,
        "isFullscreenEnabled",
        function (isFullscreenEnabled) {
          fullscreenContainer.style.display = isFullscreenEnabled
            ? "block"
            : "none";
          if (defined(timeline)) {
            timeline.container.style.right =
              fullscreenContainer.clientWidth + "px";
            timeline.resize();
          }
        }
      );
    }

    // VR
    var vrButton;
    var vrSubscription;
    var vrModeSubscription;
    if (options.vrButton) {
      var vrContainer = document.createElement("div");
      vrContainer.className = "cesium-viewer-vrContainer";
      viewerContainer.appendChild(vrContainer);
      vrButton = new VRButton(vrContainer, scene, options.fullScreenElement);

      vrSubscription = subscribeAndEvaluate(
        vrButton.viewModel,
        "isVREnabled",
        function (isVREnabled) {
          vrContainer.style.display = isVREnabled ? "block" : "none";
          if (defined(fullscreenButton)) {
            vrContainer.style.right = fullscreenContainer.clientWidth + "px";
          }
          if (defined(timeline)) {
            timeline.container.style.right = vrContainer.clientWidth + "px";
            timeline.resize();
          }
        }
      );

      vrModeSubscription = subscribeAndEvaluate(
        vrButton.viewModel,
        "isVRMode",
        function (isVRMode) {
          enableVRUI(that, isVRMode);
        }
      );
    }

    //Assign all properties to this instance.  No "this" assignments should
    //take place above this line.
    this._baseLayerPickerDropDown = baseLayerPickerDropDown;
    this._fullscreenSubscription = fullscreenSubscription;
    this._vrSubscription = vrSubscription;
    this._vrModeSubscription = vrModeSubscription;
    this._dataSourceChangedListeners = {};
    this._automaticallyTrackDataSourceClocks = defaultValue(
      options.automaticallyTrackDataSourceClocks,
      true
    );
    this._container = container;
    this._bottomContainer = bottomContainer;
    this._element = viewerContainer;
    this._cesiumWidget = cesiumWidget;
    this._selectionIndicator = selectionIndicator;
    this._infoBox = infoBox;
    this._dataSourceCollection = dataSourceCollection;
    this._destroyDataSourceCollection = destroyDataSourceCollection;
    this._dataSourceDisplay = dataSourceDisplay;
    this._clockViewModel = clockViewModel;
    this._destroyClockViewModel = destroyClockViewModel;
    this._toolbar = toolbar;
    this._homeButton = homeButton;
    this._sceneModePicker = sceneModePicker;
    this._projectionPicker = projectionPicker;
    this._baseLayerPicker = baseLayerPicker;
    this._navigationHelpButton = navigationHelpButton;
    this._animation = animation;
    this._timeline = timeline;
    this._fullscreenButton = fullscreenButton;
    this._vrButton = vrButton;
    this._geocoder = geocoder;
    this._eventHelper = eventHelper;
    this._lastWidth = 0;
    this._lastHeight = 0;
    this._allowDataSourcesToSuspendAnimation = true;
    this._entityView = undefined;
    this._enableInfoOrSelection = defined(infoBox) || defined(selectionIndicator);
    this._clockTrackedDataSource = undefined;
    this._trackedEntity = undefined;
    this._needTrackedEntityUpdate = false;
    this._selectedEntity = undefined;
    this._clockTrackedDataSource = undefined;
    this._zoomIsFlight = false;
    this._zoomTarget = undefined;
    this._zoomPromise = undefined;
    this._zoomOptions = undefined;
    this._selectedEntityChanged = new Event();
    this._trackedEntityChanged = new Event();

    knockout.track(this, [
      "_trackedEntity",
      "_selectedEntity",
      "_clockTrackedDataSource",
    ]);

    //Listen to data source events in order to track clock changes.
    eventHelper.add(
      dataSourceCollection.dataSourceAdded,
      Viewer.prototype._onDataSourceAdded,
      this
    );
    eventHelper.add(
      dataSourceCollection.dataSourceRemoved,
      Viewer.prototype._onDataSourceRemoved,
      this
    );

    // Prior to each render, check if anything needs to be resized.
    eventHelper.add(scene.postUpdate, Viewer.prototype.resize, this);
    eventHelper.add(scene.postRender, Viewer.prototype._postRender, this);

    // We need to subscribe to the data sources and collections so that we can clear the
    // tracked object when it is removed from the scene.
    // Subscribe to current data sources
    var dataSourceLength = dataSourceCollection.length;
    for (var i = 0; i < dataSourceLength; i++) {
      this._dataSourceAdded(dataSourceCollection, dataSourceCollection.get(i));
    }
    this._dataSourceAdded(undefined, dataSourceDisplay.defaultDataSource);

    // Hook up events so that we can subscribe to future sources.
    eventHelper.add(
      dataSourceCollection.dataSourceAdded,
      Viewer.prototype._dataSourceAdded,
      this
    );
    eventHelper.add(
      dataSourceCollection.dataSourceRemoved,
      Viewer.prototype._dataSourceRemoved,
      this
    );

    // Subscribe to left clicks and zoom to the picked object.
    function pickAndTrackObject(e) {
      var entity = pickEntity(that, e);
      if (defined(entity)) {
        //Only track the entity if it has a valid position at the current time.
        if (
          Property.getValueOrUndefined(entity.position, that.clock.currentTime)
        ) {
          that.trackedEntity = entity;
        } else {
          that.zoomTo(entity);
        }
      } else if (defined(that.trackedEntity)) {
        that.trackedEntity = undefined;
      }
    }

    function pickAndSelectObject(e) {
      that.selectedEntity = pickEntity(that, e);
    }

    cesiumWidget.screenSpaceEventHandler.setInputAction(
      pickAndSelectObject,
      ScreenSpaceEventType$1.LEFT_CLICK
    );
    cesiumWidget.screenSpaceEventHandler.setInputAction(
      pickAndTrackObject,
      ScreenSpaceEventType$1.LEFT_DOUBLE_CLICK
    );
  }

  Object.defineProperties(Viewer.prototype, {
    /**
     * Gets the parent container.
     * @memberof Viewer.prototype
     * @type {Element}
     * @readonly
     */
    container: {
      get: function () {
        return this._container;
      },
    },

    /**
     * Gets the DOM element for the area at the bottom of the window containing the
     * {@link CreditDisplay} and potentially other things.
     * @memberof Viewer.prototype
     * @type {Element}
     * @readonly
     */
    bottomContainer: {
      get: function () {
        return this._bottomContainer;
      },
    },

    /**
     * Gets the CesiumWidget.
     * @memberof Viewer.prototype
     * @type {CesiumWidget}
     * @readonly
     */
    cesiumWidget: {
      get: function () {
        return this._cesiumWidget;
      },
    },

    /**
     * Gets the selection indicator.
     * @memberof Viewer.prototype
     * @type {SelectionIndicator}
     * @readonly
     */
    selectionIndicator: {
      get: function () {
        return this._selectionIndicator;
      },
    },

    /**
     * Gets the info box.
     * @memberof Viewer.prototype
     * @type {InfoBox}
     * @readonly
     */
    infoBox: {
      get: function () {
        return this._infoBox;
      },
    },

    /**
     * Gets the Geocoder.
     * @memberof Viewer.prototype
     * @type {Geocoder}
     * @readonly
     */
    geocoder: {
      get: function () {
        return this._geocoder;
      },
    },

    /**
     * Gets the HomeButton.
     * @memberof Viewer.prototype
     * @type {HomeButton}
     * @readonly
     */
    homeButton: {
      get: function () {
        return this._homeButton;
      },
    },

    /**
     * Gets the SceneModePicker.
     * @memberof Viewer.prototype
     * @type {SceneModePicker}
     * @readonly
     */
    sceneModePicker: {
      get: function () {
        return this._sceneModePicker;
      },
    },

    /**
     * Gets the ProjectionPicker.
     * @memberof Viewer.prototype
     * @type {ProjectionPicker}
     * @readonly
     */
    projectionPicker: {
      get: function () {
        return this._projectionPicker;
      },
    },

    /**
     * Gets the BaseLayerPicker.
     * @memberof Viewer.prototype
     * @type {BaseLayerPicker}
     * @readonly
     */
    baseLayerPicker: {
      get: function () {
        return this._baseLayerPicker;
      },
    },

    /**
     * Gets the NavigationHelpButton.
     * @memberof Viewer.prototype
     * @type {NavigationHelpButton}
     * @readonly
     */
    navigationHelpButton: {
      get: function () {
        return this._navigationHelpButton;
      },
    },

    /**
     * Gets the Animation widget.
     * @memberof Viewer.prototype
     * @type {Animation}
     * @readonly
     */
    animation: {
      get: function () {
        return this._animation;
      },
    },

    /**
     * Gets the Timeline widget.
     * @memberof Viewer.prototype
     * @type {Timeline}
     * @readonly
     */
    timeline: {
      get: function () {
        return this._timeline;
      },
    },

    /**
     * Gets the FullscreenButton.
     * @memberof Viewer.prototype
     * @type {FullscreenButton}
     * @readonly
     */
    fullscreenButton: {
      get: function () {
        return this._fullscreenButton;
      },
    },

    /**
     * Gets the VRButton.
     * @memberof Viewer.prototype
     * @type {VRButton}
     * @readonly
     */
    vrButton: {
      get: function () {
        return this._vrButton;
      },
    },

    /**
     * Gets the display used for {@link DataSource} visualization.
     * @memberof Viewer.prototype
     * @type {DataSourceDisplay}
     * @readonly
     */
    dataSourceDisplay: {
      get: function () {
        return this._dataSourceDisplay;
      },
    },

    /**
     * Gets the collection of entities not tied to a particular data source.
     * This is a shortcut to [dataSourceDisplay.defaultDataSource.entities]{@link Viewer#dataSourceDisplay}.
     * @memberof Viewer.prototype
     * @type {EntityCollection}
     * @readonly
     */
    entities: {
      get: function () {
        return this._dataSourceDisplay.defaultDataSource.entities;
      },
    },

    /**
     * Gets the set of {@link DataSource} instances to be visualized.
     * @memberof Viewer.prototype
     * @type {DataSourceCollection}
     * @readonly
     */
    dataSources: {
      get: function () {
        return this._dataSourceCollection;
      },
    },

    /**
     * Gets the canvas.
     * @memberof Viewer.prototype
     * @type {HTMLCanvasElement}
     * @readonly
     */
    canvas: {
      get: function () {
        return this._cesiumWidget.canvas;
      },
    },

    /**
     * Gets the scene.
     * @memberof Viewer.prototype
     * @type {Scene}
     * @readonly
     */
    scene: {
      get: function () {
        return this._cesiumWidget.scene;
      },
    },

    /**
     * Determines if shadows are cast by light sources.
     * @memberof Viewer.prototype
     * @type {Boolean}
     */
    shadows: {
      get: function () {
        return this.scene.shadowMap.enabled;
      },
      set: function (value) {
        this.scene.shadowMap.enabled = value;
      },
    },

    /**
     * Determines if the terrain casts or shadows from light sources.
     * @memberof Viewer.prototype
     * @type {ShadowMode}
     */
    terrainShadows: {
      get: function () {
        return this.scene.globe.shadows;
      },
      set: function (value) {
        this.scene.globe.shadows = value;
      },
    },

    /**
     * Get the scene's shadow map
     * @memberof Viewer.prototype
     * @type {ShadowMap}
     * @readonly
     */
    shadowMap: {
      get: function () {
        return this.scene.shadowMap;
      },
    },

    /**
     * Gets the collection of image layers that will be rendered on the globe.
     * @memberof Viewer.prototype
     *
     * @type {ImageryLayerCollection}
     * @readonly
     */
    imageryLayers: {
      get: function () {
        return this.scene.imageryLayers;
      },
    },

    /**
     * The terrain provider providing surface geometry for the globe.
     * @memberof Viewer.prototype
     *
     * @type {TerrainProvider}
     */
    terrainProvider: {
      get: function () {
        return this.scene.terrainProvider;
      },
      set: function (terrainProvider) {
        this.scene.terrainProvider = terrainProvider;
      },
    },

    /**
     * Gets the camera.
     * @memberof Viewer.prototype
     *
     * @type {Camera}
     * @readonly
     */
    camera: {
      get: function () {
        return this.scene.camera;
      },
    },

    /**
     * Gets the post-process stages.
     * @memberof Viewer.prototype
     *
     * @type {PostProcessStageCollection}
     * @readonly
     */
    postProcessStages: {
      get: function () {
        return this.scene.postProcessStages;
      },
    },

    /**
     * Gets the clock.
     * @memberof Viewer.prototype
     * @type {Clock}
     * @readonly
     */
    clock: {
      get: function () {
        return this._clockViewModel.clock;
      },
    },

    /**
     * Gets the clock view model.
     * @memberof Viewer.prototype
     * @type {ClockViewModel}
     * @readonly
     */
    clockViewModel: {
      get: function () {
        return this._clockViewModel;
      },
    },

    /**
     * Gets the screen space event handler.
     * @memberof Viewer.prototype
     * @type {ScreenSpaceEventHandler}
     * @readonly
     */
    screenSpaceEventHandler: {
      get: function () {
        return this._cesiumWidget.screenSpaceEventHandler;
      },
    },

    /**
     * Gets or sets the target frame rate of the widget when <code>useDefaultRenderLoop</code>
     * is true. If undefined, the browser's {@link requestAnimationFrame} implementation
     * determines the frame rate.  If defined, this value must be greater than 0.  A value higher
     * than the underlying requestAnimationFrame implementation will have no effect.
     * @memberof Viewer.prototype
     *
     * @type {Number}
     */
    targetFrameRate: {
      get: function () {
        return this._cesiumWidget.targetFrameRate;
      },
      set: function (value) {
        this._cesiumWidget.targetFrameRate = value;
      },
    },

    /**
     * Gets or sets whether or not this widget should control the render loop.
     * If set to true the widget will use {@link requestAnimationFrame} to
     * perform rendering and resizing of the widget, as well as drive the
     * simulation clock. If set to false, you must manually call the
     * <code>resize</code>, <code>render</code> methods
     * as part of a custom render loop.  If an error occurs during rendering, {@link Scene}'s
     * <code>renderError</code> event will be raised and this property
     * will be set to false.  It must be set back to true to continue rendering
     * after the error.
     * @memberof Viewer.prototype
     *
     * @type {Boolean}
     */
    useDefaultRenderLoop: {
      get: function () {
        return this._cesiumWidget.useDefaultRenderLoop;
      },
      set: function (value) {
        this._cesiumWidget.useDefaultRenderLoop = value;
      },
    },

    /**
     * Gets or sets a scaling factor for rendering resolution.  Values less than 1.0 can improve
     * performance on less powerful devices while values greater than 1.0 will render at a higher
     * resolution and then scale down, resulting in improved visual fidelity.
     * For example, if the widget is laid out at a size of 640x480, setting this value to 0.5
     * will cause the scene to be rendered at 320x240 and then scaled up while setting
     * it to 2.0 will cause the scene to be rendered at 1280x960 and then scaled down.
     * @memberof Viewer.prototype
     *
     * @type {Number}
     * @default 1.0
     */
    resolutionScale: {
      get: function () {
        return this._cesiumWidget.resolutionScale;
      },
      set: function (value) {
        this._cesiumWidget.resolutionScale = value;
      },
    },

    /**
     * Boolean flag indicating if the browser's recommended resolution is used.
     * If true, the browser's device pixel ratio is ignored and 1.0 is used instead,
     * effectively rendering based on CSS pixels instead of device pixels. This can improve
     * performance on less powerful devices that have high pixel density. When false, rendering
     * will be in device pixels. {@link Viewer#resolutionScale} will still take effect whether
     * this flag is true or false.
     * @memberof Viewer.prototype
     *
     * @type {Boolean}
     * @default true
     */
    useBrowserRecommendedResolution: {
      get: function () {
        return this._cesiumWidget.useBrowserRecommendedResolution;
      },
      set: function (value) {
        this._cesiumWidget.useBrowserRecommendedResolution = value;
      },
    },

    /**
     * Gets or sets whether or not data sources can temporarily pause
     * animation in order to avoid showing an incomplete picture to the user.
     * For example, if asynchronous primitives are being processed in the
     * background, the clock will not advance until the geometry is ready.
     *
     * @memberof Viewer.prototype
     *
     * @type {Boolean}
     */
    allowDataSourcesToSuspendAnimation: {
      get: function () {
        return this._allowDataSourcesToSuspendAnimation;
      },
      set: function (value) {
        this._allowDataSourcesToSuspendAnimation = value;
      },
    },

    /**
     * Gets or sets the Entity instance currently being tracked by the camera.
     * @memberof Viewer.prototype
     * @type {Entity | undefined}
     */
    trackedEntity: {
      get: function () {
        return this._trackedEntity;
      },
      set: function (value) {
        if (this._trackedEntity !== value) {
          this._trackedEntity = value;

          //Cancel any pending zoom
          cancelZoom(this);

          var scene = this.scene;
          var sceneMode = scene.mode;

          //Stop tracking
          if (!defined(value) || !defined(value.position)) {
            this._needTrackedEntityUpdate = false;
            if (
              sceneMode === SceneMode$1.COLUMBUS_VIEW ||
              sceneMode === SceneMode$1.SCENE2D
            ) {
              scene.screenSpaceCameraController.enableTranslate = true;
            }

            if (
              sceneMode === SceneMode$1.COLUMBUS_VIEW ||
              sceneMode === SceneMode$1.SCENE3D
            ) {
              scene.screenSpaceCameraController.enableTilt = true;
            }

            this._entityView = undefined;
            this.camera.lookAtTransform(Matrix4.IDENTITY);
          } else {
            //We can't start tracking immediately, so we set a flag and start tracking
            //when the bounding sphere is ready (most likely next frame).
            this._needTrackedEntityUpdate = true;
          }

          this._trackedEntityChanged.raiseEvent(value);
          this.scene.requestRender();
        }
      },
    },
    /**
     * Gets or sets the object instance for which to display a selection indicator.
     * @memberof Viewer.prototype
     * @type {Entity | undefined}
     */
    selectedEntity: {
      get: function () {
        return this._selectedEntity;
      },
      set: function (value) {
        if (this._selectedEntity !== value) {
          this._selectedEntity = value;
          var selectionIndicatorViewModel = defined(this._selectionIndicator)
            ? this._selectionIndicator.viewModel
            : undefined;
          if (defined(value)) {
            if (defined(selectionIndicatorViewModel)) {
              selectionIndicatorViewModel.animateAppear();
            }
          } else if (defined(selectionIndicatorViewModel)) {
            // Leave the info text in place here, it is needed during the exit animation.
            selectionIndicatorViewModel.animateDepart();
          }
          this._selectedEntityChanged.raiseEvent(value);
        }
      },
    },
    /**
     * Gets the event that is raised when the selected entity changes.
     * @memberof Viewer.prototype
     * @type {Event}
     * @readonly
     */
    selectedEntityChanged: {
      get: function () {
        return this._selectedEntityChanged;
      },
    },
    /**
     * Gets the event that is raised when the tracked entity changes.
     * @memberof Viewer.prototype
     * @type {Event}
     * @readonly
     */
    trackedEntityChanged: {
      get: function () {
        return this._trackedEntityChanged;
      },
    },
    /**
     * Gets or sets the data source to track with the viewer's clock.
     * @memberof Viewer.prototype
     * @type {DataSource}
     */
    clockTrackedDataSource: {
      get: function () {
        return this._clockTrackedDataSource;
      },
      set: function (value) {
        if (this._clockTrackedDataSource !== value) {
          this._clockTrackedDataSource = value;
          trackDataSourceClock(this._timeline, this.clock, value);
        }
      },
    },
  });

  /**
   * Extends the base viewer functionality with the provided mixin.
   * A mixin may add additional properties, functions, or other behavior
   * to the provided viewer instance.
   *
   * @param {Viewer.ViewerMixin} mixin The Viewer mixin to add to this instance.
   * @param {Object} [options] The options object to be passed to the mixin function.
   *
   * @see viewerDragDropMixin
   */
  Viewer.prototype.extend = function (mixin, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(mixin)) {
      throw new DeveloperError("mixin is required.");
    }
    //>>includeEnd('debug')

    mixin(this, options);
  };

  /**
   * Resizes the widget to match the container size.
   * This function is called automatically as needed unless
   * <code>useDefaultRenderLoop</code> is set to false.
   */
  Viewer.prototype.resize = function () {
    var cesiumWidget = this._cesiumWidget;
    var container = this._container;
    var width = container.clientWidth;
    var height = container.clientHeight;
    var animationExists = defined(this._animation);
    var timelineExists = defined(this._timeline);

    cesiumWidget.resize();

    if (width === this._lastWidth && height === this._lastHeight) {
      return;
    }

    var panelMaxHeight = height - 125;
    var baseLayerPickerDropDown = this._baseLayerPickerDropDown;

    if (defined(baseLayerPickerDropDown)) {
      baseLayerPickerDropDown.style.maxHeight = panelMaxHeight + "px";
    }

    if (defined(this._geocoder)) {
      var geocoderSuggestions = this._geocoder.searchSuggestionsContainer;
      geocoderSuggestions.style.maxHeight = panelMaxHeight + "px";
    }

    if (defined(this._infoBox)) {
      this._infoBox.viewModel.maxHeight = panelMaxHeight;
    }

    var timeline = this._timeline;
    var animationContainer;
    var animationWidth = 0;
    var creditLeft = 0;
    var creditBottom = 0;

    if (
      animationExists &&
      window.getComputedStyle(this._animation.container).visibility !== "hidden"
    ) {
      var lastWidth = this._lastWidth;
      animationContainer = this._animation.container;
      if (width > 900) {
        animationWidth = 169;
        if (lastWidth <= 900) {
          animationContainer.style.width = "169px";
          animationContainer.style.height = "112px";
          this._animation.resize();
        }
      } else if (width >= 600) {
        animationWidth = 136;
        if (lastWidth < 600 || lastWidth > 900) {
          animationContainer.style.width = "136px";
          animationContainer.style.height = "90px";
          this._animation.resize();
        }
      } else {
        animationWidth = 106;
        if (lastWidth > 600 || lastWidth === 0) {
          animationContainer.style.width = "106px";
          animationContainer.style.height = "70px";
          this._animation.resize();
        }
      }
      creditLeft = animationWidth + 5;
    }

    if (
      timelineExists &&
      window.getComputedStyle(this._timeline.container).visibility !== "hidden"
    ) {
      var fullscreenButton = this._fullscreenButton;
      var vrButton = this._vrButton;
      var timelineContainer = timeline.container;
      var timelineStyle = timelineContainer.style;

      creditBottom = timelineContainer.clientHeight + 3;
      timelineStyle.left = animationWidth + "px";

      var pixels = 0;
      if (defined(fullscreenButton)) {
        pixels += fullscreenButton.container.clientWidth;
      }
      if (defined(vrButton)) {
        pixels += vrButton.container.clientWidth;
      }

      timelineStyle.right = pixels + "px";
      timeline.resize();
    }

    this._bottomContainer.style.left = creditLeft + "px";
    this._bottomContainer.style.bottom = creditBottom + "px";

    this._lastWidth = width;
    this._lastHeight = height;
  };

  /**
   * This forces the widget to re-think its layout, including
   * widget sizes and credit placement.
   */
  Viewer.prototype.forceResize = function () {
    this._lastWidth = 0;
    this.resize();
  };

  /**
   * Renders the scene.  This function is called automatically
   * unless <code>useDefaultRenderLoop</code> is set to false;
   */
  Viewer.prototype.render = function () {
    this._cesiumWidget.render();
  };

  /**
   * @returns {Boolean} true if the object has been destroyed, false otherwise.
   */
  Viewer.prototype.isDestroyed = function () {
    return false;
  };

  /**
   * Destroys the widget.  Should be called if permanently
   * removing the widget from layout.
   */
  Viewer.prototype.destroy = function () {
    var i;

    this.screenSpaceEventHandler.removeInputAction(
      ScreenSpaceEventType$1.LEFT_CLICK
    );
    this.screenSpaceEventHandler.removeInputAction(
      ScreenSpaceEventType$1.LEFT_DOUBLE_CLICK
    );

    // Unsubscribe from data sources
    var dataSources = this.dataSources;
    var dataSourceLength = dataSources.length;
    for (i = 0; i < dataSourceLength; i++) {
      this._dataSourceRemoved(dataSources, dataSources.get(i));
    }
    this._dataSourceRemoved(undefined, this._dataSourceDisplay.defaultDataSource);

    this._container.removeChild(this._element);
    this._element.removeChild(this._toolbar);

    this._eventHelper.removeAll();

    if (defined(this._geocoder)) {
      this._geocoder = this._geocoder.destroy();
    }

    if (defined(this._homeButton)) {
      this._homeButton = this._homeButton.destroy();
    }

    if (defined(this._sceneModePicker)) {
      this._sceneModePicker = this._sceneModePicker.destroy();
    }

    if (defined(this._projectionPicker)) {
      this._projectionPicker = this._projectionPicker.destroy();
    }

    if (defined(this._baseLayerPicker)) {
      this._baseLayerPicker = this._baseLayerPicker.destroy();
    }

    if (defined(this._animation)) {
      this._element.removeChild(this._animation.container);
      this._animation = this._animation.destroy();
    }

    if (defined(this._timeline)) {
      this._timeline.removeEventListener(
        "settime",
        onTimelineScrubfunction,
        false
      );
      this._element.removeChild(this._timeline.container);
      this._timeline = this._timeline.destroy();
    }

    if (defined(this._fullscreenButton)) {
      this._fullscreenSubscription.dispose();
      this._element.removeChild(this._fullscreenButton.container);
      this._fullscreenButton = this._fullscreenButton.destroy();
    }

    if (defined(this._vrButton)) {
      this._vrSubscription.dispose();
      this._vrModeSubscription.dispose();
      this._element.removeChild(this._vrButton.container);
      this._vrButton = this._vrButton.destroy();
    }

    if (defined(this._infoBox)) {
      this._element.removeChild(this._infoBox.container);
      this._infoBox = this._infoBox.destroy();
    }

    if (defined(this._selectionIndicator)) {
      this._element.removeChild(this._selectionIndicator.container);
      this._selectionIndicator = this._selectionIndicator.destroy();
    }

    if (this._destroyClockViewModel) {
      this._clockViewModel = this._clockViewModel.destroy();
    }
    this._dataSourceDisplay = this._dataSourceDisplay.destroy();
    this._cesiumWidget = this._cesiumWidget.destroy();

    if (this._destroyDataSourceCollection) {
      this._dataSourceCollection = this._dataSourceCollection.destroy();
    }

    return destroyObject(this);
  };

  /**
   * @private
   */
  Viewer.prototype._dataSourceAdded = function (
    dataSourceCollection,
    dataSource
  ) {
    var entityCollection = dataSource.entities;
    entityCollection.collectionChanged.addEventListener(
      Viewer.prototype._onEntityCollectionChanged,
      this
    );
  };

  /**
   * @private
   */
  Viewer.prototype._dataSourceRemoved = function (
    dataSourceCollection,
    dataSource
  ) {
    var entityCollection = dataSource.entities;
    entityCollection.collectionChanged.removeEventListener(
      Viewer.prototype._onEntityCollectionChanged,
      this
    );

    if (defined(this.trackedEntity)) {
      if (
        entityCollection.getById(this.trackedEntity.id) === this.trackedEntity
      ) {
        this.trackedEntity = undefined;
      }
    }

    if (defined(this.selectedEntity)) {
      if (
        entityCollection.getById(this.selectedEntity.id) === this.selectedEntity
      ) {
        this.selectedEntity = undefined;
      }
    }
  };

  /**
   * @private
   */
  Viewer.prototype._onTick = function (clock) {
    var time = clock.currentTime;

    var isUpdated = this._dataSourceDisplay.update(time);
    if (this._allowDataSourcesToSuspendAnimation) {
      this._clockViewModel.canAnimate = isUpdated;
    }

    var entityView = this._entityView;
    if (defined(entityView)) {
      var trackedEntity = this._trackedEntity;
      var trackedState = this._dataSourceDisplay.getBoundingSphere(
        trackedEntity,
        false,
        boundingSphereScratch$2
      );
      if (trackedState === BoundingSphereState$1.DONE) {
        entityView.update(time, boundingSphereScratch$2);
      }
    }

    var position;
    var enableCamera = false;
    var selectedEntity = this.selectedEntity;
    var showSelection = defined(selectedEntity) && this._enableInfoOrSelection;

    if (
      showSelection &&
      selectedEntity.isShowing &&
      selectedEntity.isAvailable(time)
    ) {
      var state = this._dataSourceDisplay.getBoundingSphere(
        selectedEntity,
        true,
        boundingSphereScratch$2
      );
      if (state !== BoundingSphereState$1.FAILED) {
        position = boundingSphereScratch$2.center;
      } else if (defined(selectedEntity.position)) {
        position = selectedEntity.position.getValue(time, position);
      }
      enableCamera = defined(position);
    }

    var selectionIndicatorViewModel = defined(this._selectionIndicator)
      ? this._selectionIndicator.viewModel
      : undefined;
    if (defined(selectionIndicatorViewModel)) {
      selectionIndicatorViewModel.position = Cartesian3.clone(
        position,
        selectionIndicatorViewModel.position
      );
      selectionIndicatorViewModel.showSelection = showSelection && enableCamera;
      selectionIndicatorViewModel.update();
    }

    var infoBoxViewModel = defined(this._infoBox)
      ? this._infoBox.viewModel
      : undefined;
    if (defined(infoBoxViewModel)) {
      infoBoxViewModel.showInfo = showSelection;
      infoBoxViewModel.enableCamera = enableCamera;
      infoBoxViewModel.isCameraTracking =
        this.trackedEntity === this.selectedEntity;

      if (showSelection) {
        infoBoxViewModel.titleText = defaultValue(
          selectedEntity.name,
          selectedEntity.id
        );
        infoBoxViewModel.description = Property.getValueOrDefault(
          selectedEntity.description,
          time,
          ""
        );
      } else {
        infoBoxViewModel.titleText = "";
        infoBoxViewModel.description = "";
      }
    }
  };

  /**
   * @private
   */
  Viewer.prototype._onEntityCollectionChanged = function (
    collection,
    added,
    removed
  ) {
    var length = removed.length;
    for (var i = 0; i < length; i++) {
      var removedObject = removed[i];
      if (this.trackedEntity === removedObject) {
        this.trackedEntity = undefined;
      }
      if (this.selectedEntity === removedObject) {
        this.selectedEntity = undefined;
      }
    }
  };

  /**
   * @private
   */
  Viewer.prototype._onInfoBoxCameraClicked = function (infoBoxViewModel) {
    if (
      infoBoxViewModel.isCameraTracking &&
      this.trackedEntity === this.selectedEntity
    ) {
      this.trackedEntity = undefined;
    } else {
      var selectedEntity = this.selectedEntity;
      var position = selectedEntity.position;
      if (defined(position)) {
        this.trackedEntity = this.selectedEntity;
      } else {
        this.zoomTo(this.selectedEntity);
      }
    }
  };

  /**
   * @private
   */
  Viewer.prototype._clearTrackedObject = function () {
    this.trackedEntity = undefined;
  };

  /**
   * @private
   */
  Viewer.prototype._onInfoBoxClockClicked = function (infoBoxViewModel) {
    this.selectedEntity = undefined;
  };

  /**
   * @private
   */
  Viewer.prototype._clearObjects = function () {
    this.trackedEntity = undefined;
    this.selectedEntity = undefined;
  };

  /**
   * @private
   */
  Viewer.prototype._onDataSourceChanged = function (dataSource) {
    if (this.clockTrackedDataSource === dataSource) {
      trackDataSourceClock(this.timeline, this.clock, dataSource);
    }
  };

  /**
   * @private
   */
  Viewer.prototype._onDataSourceAdded = function (
    dataSourceCollection,
    dataSource
  ) {
    if (this._automaticallyTrackDataSourceClocks) {
      this.clockTrackedDataSource = dataSource;
    }
    var id = dataSource.entities.id;
    var removalFunc = this._eventHelper.add(
      dataSource.changedEvent,
      Viewer.prototype._onDataSourceChanged,
      this
    );
    this._dataSourceChangedListeners[id] = removalFunc;
  };

  /**
   * @private
   */
  Viewer.prototype._onDataSourceRemoved = function (
    dataSourceCollection,
    dataSource
  ) {
    var resetClock = this.clockTrackedDataSource === dataSource;
    var id = dataSource.entities.id;
    this._dataSourceChangedListeners[id]();
    this._dataSourceChangedListeners[id] = undefined;
    if (resetClock) {
      var numDataSources = dataSourceCollection.length;
      if (this._automaticallyTrackDataSourceClocks && numDataSources > 0) {
        this.clockTrackedDataSource = dataSourceCollection.get(
          numDataSources - 1
        );
      } else {
        this.clockTrackedDataSource = undefined;
      }
    }
  };

  /**
   * Asynchronously sets the camera to view the provided entity, entities, or data source.
   * If the data source is still in the process of loading or the visualization is otherwise still loading,
   * this method waits for the data to be ready before performing the zoom.
   *
   * <p>The offset is heading/pitch/range in the local east-north-up reference frame centered at the center of the bounding sphere.
   * The heading and the pitch angles are defined in the local east-north-up reference frame.
   * The heading is the angle from y axis and increasing towards the x axis. Pitch is the rotation from the xy-plane. Positive pitch
   * angles are above the plane. Negative pitch angles are below the plane. The range is the distance from the center. If the range is
   * zero, a range will be computed such that the whole bounding sphere is visible.</p>
   *
   * <p>In 2D, there must be a top down view. The camera will be placed above the target looking down. The height above the
   * target will be the range. The heading will be determined from the offset. If the heading cannot be
   * determined from the offset, the heading will be north.</p>
   *
   * @param {Entity|Entity[]|EntityCollection|DataSource|ImageryLayer|Cesium3DTileset|TimeDynamicPointCloud|Promise.<Entity|Entity[]|EntityCollection|DataSource|ImageryLayer|Cesium3DTileset|TimeDynamicPointCloud>} target The entity, array of entities, entity collection, data source, Cesium3DTileset, point cloud, or imagery layer to view. You can also pass a promise that resolves to one of the previously mentioned types.
   * @param {HeadingPitchRange} [offset] The offset from the center of the entity in the local east-north-up reference frame.
   * @returns {Promise.<Boolean>} A Promise that resolves to true if the zoom was successful or false if the target is not currently visualized in the scene or the zoom was cancelled.
   */
  Viewer.prototype.zoomTo = function (target, offset) {
    var options = {
      offset: offset,
    };
    return zoomToOrFly(this, target, options, false);
  };

  /**
   * Flies the camera to the provided entity, entities, or data source.
   * If the data source is still in the process of loading or the visualization is otherwise still loading,
   * this method waits for the data to be ready before performing the flight.
   *
   * <p>The offset is heading/pitch/range in the local east-north-up reference frame centered at the center of the bounding sphere.
   * The heading and the pitch angles are defined in the local east-north-up reference frame.
   * The heading is the angle from y axis and increasing towards the x axis. Pitch is the rotation from the xy-plane. Positive pitch
   * angles are above the plane. Negative pitch angles are below the plane. The range is the distance from the center. If the range is
   * zero, a range will be computed such that the whole bounding sphere is visible.</p>
   *
   * <p>In 2D, there must be a top down view. The camera will be placed above the target looking down. The height above the
   * target will be the range. The heading will be determined from the offset. If the heading cannot be
   * determined from the offset, the heading will be north.</p>
   *
   * @param {Entity|Entity[]|EntityCollection|DataSource|ImageryLayer|Cesium3DTileset|TimeDynamicPointCloud|Promise.<Entity|Entity[]|EntityCollection|DataSource|ImageryLayer|Cesium3DTileset|TimeDynamicPointCloud>} target The entity, array of entities, entity collection, data source, Cesium3DTileset, point cloud, or imagery layer to view. You can also pass a promise that resolves to one of the previously mentioned types.
   * @param {Object} [options] Object with the following properties:
   * @param {Number} [options.duration=3.0] The duration of the flight in seconds.
   * @param {Number} [options.maximumHeight] The maximum height at the peak of the flight.
   * @param {HeadingPitchRange} [options.offset] The offset from the target in the local east-north-up reference frame centered at the target.
   * @returns {Promise.<Boolean>} A Promise that resolves to true if the flight was successful or false if the target is not currently visualized in the scene or the flight was cancelled. //TODO: Cleanup entity mentions
   */
  Viewer.prototype.flyTo = function (target, options) {
    return zoomToOrFly(this, target, options, true);
  };

  function zoomToOrFly(that, zoomTarget, options, isFlight) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(zoomTarget)) {
      throw new DeveloperError("zoomTarget is required.");
    }
    //>>includeEnd('debug');

    cancelZoom(that);

    //We can't actually perform the zoom until all visualization is ready and
    //bounding spheres have been computed.  Therefore we create and return
    //a deferred which will be resolved as part of the post-render step in the
    //frame that actually performs the zoom
    var zoomPromise = when.defer();
    that._zoomPromise = zoomPromise;
    that._zoomIsFlight = isFlight;
    that._zoomOptions = options;

    when(zoomTarget, function (zoomTarget) {
      //Only perform the zoom if it wasn't cancelled before the promise resolved.
      if (that._zoomPromise !== zoomPromise) {
        return;
      }

      //If the zoom target is a rectangular imagery in an ImageLayer
      if (zoomTarget instanceof ImageryLayer) {
        zoomTarget
          .getViewableRectangle()
          .then(function (rectangle) {
            return computeFlyToLocationForRectangle(rectangle, that.scene);
          })
          .then(function (position) {
            //Only perform the zoom if it wasn't cancelled before the promise was resolved
            if (that._zoomPromise === zoomPromise) {
              that._zoomTarget = position;
            }
          });
        return;
      }

      //If the zoom target is a Cesium3DTileset
      if (zoomTarget instanceof Cesium3DTileset) {
        that._zoomTarget = zoomTarget;
        return;
      }

      //If the zoom target is a TimeDynamicPointCloud
      if (zoomTarget instanceof TimeDynamicPointCloud) {
        that._zoomTarget = zoomTarget;
        return;
      }

      //If the zoom target is a data source, and it's in the middle of loading, wait for it to finish loading.
      if (zoomTarget.isLoading && defined(zoomTarget.loadingEvent)) {
        var removeEvent = zoomTarget.loadingEvent.addEventListener(function () {
          removeEvent();

          //Only perform the zoom if it wasn't cancelled before the data source finished.
          if (that._zoomPromise === zoomPromise) {
            that._zoomTarget = zoomTarget.entities.values.slice(0);
          }
        });
        return;
      }

      //Zoom target is already an array, just copy it and return.
      if (Array.isArray(zoomTarget)) {
        that._zoomTarget = zoomTarget.slice(0);
        return;
      }

      //If zoomTarget is an EntityCollection, this will retrieve the array
      zoomTarget = defaultValue(zoomTarget.values, zoomTarget);

      //If zoomTarget is a DataSource, this will retrieve the array.
      if (defined(zoomTarget.entities)) {
        zoomTarget = zoomTarget.entities.values;
      }

      //Zoom target is already an array, just copy it and return.
      if (Array.isArray(zoomTarget)) {
        that._zoomTarget = zoomTarget.slice(0);
      } else {
        //Single entity
        that._zoomTarget = [zoomTarget];
      }
    });

    that.scene.requestRender();
    return zoomPromise.promise;
  }

  function clearZoom(viewer) {
    viewer._zoomPromise = undefined;
    viewer._zoomTarget = undefined;
    viewer._zoomOptions = undefined;
  }

  function cancelZoom(viewer) {
    var zoomPromise = viewer._zoomPromise;
    if (defined(zoomPromise)) {
      clearZoom(viewer);
      zoomPromise.resolve(false);
    }
  }

  /**
   * @private
   */
  Viewer.prototype._postRender = function () {
    updateZoomTarget(this);
    updateTrackedEntity(this);
  };

  function updateZoomTarget(viewer) {
    var target = viewer._zoomTarget;
    if (!defined(target) || viewer.scene.mode === SceneMode$1.MORPHING) {
      return;
    }

    var scene = viewer.scene;
    var camera = scene.camera;
    var zoomPromise = viewer._zoomPromise;
    var zoomOptions = defaultValue(viewer._zoomOptions, {});
    var options;
    var boundingSphere;

    // If zoomTarget was Cesium3DTileset
    if (target instanceof Cesium3DTileset) {
      return target.readyPromise.then(function () {
        var boundingSphere = target.boundingSphere;
        // If offset was originally undefined then give it base value instead of empty object
        if (!defined(zoomOptions.offset)) {
          zoomOptions.offset = new HeadingPitchRange(
            0.0,
            -0.5,
            boundingSphere.radius
          );
        }

        options = {
          offset: zoomOptions.offset,
          duration: zoomOptions.duration,
          maximumHeight: zoomOptions.maximumHeight,
          complete: function () {
            zoomPromise.resolve(true);
          },
          cancel: function () {
            zoomPromise.resolve(false);
          },
        };

        if (viewer._zoomIsFlight) {
          camera.flyToBoundingSphere(target.boundingSphere, options);
        } else {
          camera.viewBoundingSphere(boundingSphere, zoomOptions.offset);
          camera.lookAtTransform(Matrix4.IDENTITY);

          // Finish the promise
          zoomPromise.resolve(true);
        }

        clearZoom(viewer);
      });
    }

    // If zoomTarget was TimeDynamicPointCloud
    if (target instanceof TimeDynamicPointCloud) {
      return target.readyPromise.then(function () {
        var boundingSphere = target.boundingSphere;
        // If offset was originally undefined then give it base value instead of empty object
        if (!defined(zoomOptions.offset)) {
          zoomOptions.offset = new HeadingPitchRange(
            0.0,
            -0.5,
            boundingSphere.radius
          );
        }

        options = {
          offset: zoomOptions.offset,
          duration: zoomOptions.duration,
          maximumHeight: zoomOptions.maximumHeight,
          complete: function () {
            zoomPromise.resolve(true);
          },
          cancel: function () {
            zoomPromise.resolve(false);
          },
        };

        if (viewer._zoomIsFlight) {
          camera.flyToBoundingSphere(boundingSphere, options);
        } else {
          camera.viewBoundingSphere(boundingSphere, zoomOptions.offset);
          camera.lookAtTransform(Matrix4.IDENTITY);

          // Finish the promise
          zoomPromise.resolve(true);
        }

        clearZoom(viewer);
      });
    }

    // If zoomTarget was an ImageryLayer
    if (target instanceof Cartographic) {
      options = {
        destination: scene.mapProjection.ellipsoid.cartographicToCartesian(
          target
        ),
        duration: zoomOptions.duration,
        maximumHeight: zoomOptions.maximumHeight,
        complete: function () {
          zoomPromise.resolve(true);
        },
        cancel: function () {
          zoomPromise.resolve(false);
        },
      };

      if (viewer._zoomIsFlight) {
        camera.flyTo(options);
      } else {
        camera.setView(options);
        zoomPromise.resolve(true);
      }
      clearZoom(viewer);
      return;
    }

    var entities = target;

    var boundingSpheres = [];
    for (var i = 0, len = entities.length; i < len; i++) {
      var state = viewer._dataSourceDisplay.getBoundingSphere(
        entities[i],
        false,
        boundingSphereScratch$2
      );

      if (state === BoundingSphereState$1.PENDING) {
        return;
      } else if (state !== BoundingSphereState$1.FAILED) {
        boundingSpheres.push(BoundingSphere.clone(boundingSphereScratch$2));
      }
    }

    if (boundingSpheres.length === 0) {
      cancelZoom(viewer);
      return;
    }

    //Stop tracking the current entity.
    viewer.trackedEntity = undefined;

    boundingSphere = BoundingSphere.fromBoundingSpheres(boundingSpheres);

    if (!viewer._zoomIsFlight) {
      camera.viewBoundingSphere(boundingSphere, zoomOptions.offset);
      camera.lookAtTransform(Matrix4.IDENTITY);
      clearZoom(viewer);
      zoomPromise.resolve(true);
    } else {
      clearZoom(viewer);
      camera.flyToBoundingSphere(boundingSphere, {
        duration: zoomOptions.duration,
        maximumHeight: zoomOptions.maximumHeight,
        complete: function () {
          zoomPromise.resolve(true);
        },
        cancel: function () {
          zoomPromise.resolve(false);
        },
        offset: zoomOptions.offset,
      });
    }
  }

  function updateTrackedEntity(viewer) {
    if (!viewer._needTrackedEntityUpdate) {
      return;
    }

    var trackedEntity = viewer._trackedEntity;
    var currentTime = viewer.clock.currentTime;

    //Verify we have a current position at this time. This is only triggered if a position
    //has become undefined after trackedEntity is set but before the boundingSphere has been
    //computed. In this case, we will track the entity once it comes back into existence.
    var currentPosition = Property.getValueOrUndefined(
      trackedEntity.position,
      currentTime
    );

    if (!defined(currentPosition)) {
      return;
    }

    var scene = viewer.scene;

    var state = viewer._dataSourceDisplay.getBoundingSphere(
      trackedEntity,
      false,
      boundingSphereScratch$2
    );
    if (state === BoundingSphereState$1.PENDING) {
      return;
    }

    var sceneMode = scene.mode;
    if (
      sceneMode === SceneMode$1.COLUMBUS_VIEW ||
      sceneMode === SceneMode$1.SCENE2D
    ) {
      scene.screenSpaceCameraController.enableTranslate = false;
    }

    if (
      sceneMode === SceneMode$1.COLUMBUS_VIEW ||
      sceneMode === SceneMode$1.SCENE3D
    ) {
      scene.screenSpaceCameraController.enableTilt = false;
    }

    var bs =
      state !== BoundingSphereState$1.FAILED ? boundingSphereScratch$2 : undefined;
    viewer._entityView = new EntityView(
      trackedEntity,
      scene,
      scene.mapProjection.ellipsoid
    );
    viewer._entityView.update(currentTime, bs);
    viewer._needTrackedEntityUpdate = false;
  }

  /**
   * A mixin which adds the {@link Cesium3DTilesInspector} widget to the {@link Viewer} widget.
   * Rather than being called directly, this function is normally passed as
   * a parameter to {@link Viewer#extend}, as shown in the example below.
   * @function
   *
   * @param {Viewer} viewer The viewer instance.
   *
   * @example
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.extend(Cesium.viewerCesium3DTilesInspectorMixin);
   */
  function viewerCesium3DTilesInspectorMixin(viewer) {
    //>>includeStart('debug', pragmas.debug);
    Check.typeOf.object("viewer", viewer);
    //>>includeEnd('debug');

    var container = document.createElement("div");
    container.className = "cesium-viewer-cesium3DTilesInspectorContainer";
    viewer.container.appendChild(container);
    var cesium3DTilesInspector = new Cesium3DTilesInspector(
      container,
      viewer.scene
    );

    Object.defineProperties(viewer, {
      cesium3DTilesInspector: {
        get: function () {
          return cesium3DTilesInspector;
        },
      },
    });
  }

  /**
   * A mixin which adds the CesiumInspector widget to the Viewer widget.
   * Rather than being called directly, this function is normally passed as
   * a parameter to {@link Viewer#extend}, as shown in the example below.
   * @function
   *
   * @param {Viewer} viewer The viewer instance.
   *
   * @exception {DeveloperError} viewer is required.
   *
   * @demo {@link https://sandcastle.cesium.com/index.html?src=Cesium%20Inspector.html|Cesium Sandcastle Cesium Inspector Demo}
   *
   * @example
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.extend(Cesium.viewerCesiumInspectorMixin);
   */
  function viewerCesiumInspectorMixin(viewer) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(viewer)) {
      throw new DeveloperError("viewer is required.");
    }
    //>>includeEnd('debug');

    var cesiumInspectorContainer = document.createElement("div");
    cesiumInspectorContainer.className = "cesium-viewer-cesiumInspectorContainer";
    viewer.container.appendChild(cesiumInspectorContainer);
    var cesiumInspector = new CesiumInspector(
      cesiumInspectorContainer,
      viewer.scene
    );

    Object.defineProperties(viewer, {
      cesiumInspector: {
        get: function () {
          return cesiumInspector;
        },
      },
    });
  }

  /**
   * A mixin which adds default drag and drop support for CZML files to the Viewer widget.
   * Rather than being called directly, this function is normally passed as
   * a parameter to {@link Viewer#extend}, as shown in the example below.
   * @function viewerDragDropMixin

   * @param {Viewer} viewer The viewer instance.
   * @param {Object} [options] Object with the following properties:
   * @param {Element|String} [options.dropTarget=viewer.container] The DOM element which will serve as the drop target.
   * @param {Boolean} [options.clearOnDrop=true] When true, dropping files will clear all existing data sources first, when false, new data sources will be loaded after the existing ones.
   * @param {Boolean} [options.flyToOnDrop=true] When true, dropping files will fly to the data source once it is loaded.
   * @param {Boolean} [options.clampToGround=true] When true, datasources are clamped to the ground.
   * @param {Proxy} [options.proxy] The proxy to be used for KML network links.
   *
   * @exception {DeveloperError} Element with id <options.dropTarget> does not exist in the document.
   * @exception {DeveloperError} dropTarget is already defined by another mixin.
   * @exception {DeveloperError} dropEnabled is already defined by another mixin.
   * @exception {DeveloperError} dropError is already defined by another mixin.
   * @exception {DeveloperError} clearOnDrop is already defined by another mixin.
   *
   * @example
   * // Add basic drag and drop support and pop up an alert window on error.
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.extend(Cesium.viewerDragDropMixin);
   * viewer.dropError.addEventListener(function(viewerArg, source, error) {
   *     window.alert('Error processing ' + source + ':' + error);
   * });
   */
  function viewerDragDropMixin(viewer, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(viewer)) {
      throw new DeveloperError("viewer is required.");
    }
    if (viewer.hasOwnProperty("dropTarget")) {
      throw new DeveloperError("dropTarget is already defined by another mixin.");
    }
    if (viewer.hasOwnProperty("dropEnabled")) {
      throw new DeveloperError(
        "dropEnabled is already defined by another mixin."
      );
    }
    if (viewer.hasOwnProperty("dropError")) {
      throw new DeveloperError("dropError is already defined by another mixin.");
    }
    if (viewer.hasOwnProperty("clearOnDrop")) {
      throw new DeveloperError(
        "clearOnDrop is already defined by another mixin."
      );
    }
    if (viewer.hasOwnProperty("flyToOnDrop")) {
      throw new DeveloperError(
        "flyToOnDrop is already defined by another mixin."
      );
    }
    //>>includeEnd('debug');

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    //Local variables to be closed over by defineProperties.
    var dropEnabled = true;
    var flyToOnDrop = defaultValue(options.flyToOnDrop, true);
    var dropError = new Event();
    var clearOnDrop = defaultValue(options.clearOnDrop, true);
    var dropTarget = defaultValue(options.dropTarget, viewer.container);
    var clampToGround = defaultValue(options.clampToGround, true);
    var proxy = options.proxy;

    dropTarget = getElement(dropTarget);

    Object.defineProperties(viewer, {
      /**
       * Gets or sets the element to serve as the drop target.
       * @memberof viewerDragDropMixin.prototype
       * @type {Element}
       */
      dropTarget: {
        //TODO See https://github.com/CesiumGS/cesium/issues/832
        get: function () {
          return dropTarget;
        },
        set: function (value) {
          //>>includeStart('debug', pragmas.debug);
          if (!defined(value)) {
            throw new DeveloperError("value is required.");
          }
          //>>includeEnd('debug');

          unsubscribe(dropTarget, handleDrop);
          dropTarget = value;
          subscribe(dropTarget, handleDrop);
        },
      },

      /**
       * Gets or sets a value indicating if drag and drop support is enabled.
       * @memberof viewerDragDropMixin.prototype
       * @type {Element}
       */
      dropEnabled: {
        get: function () {
          return dropEnabled;
        },
        set: function (value) {
          if (value !== dropEnabled) {
            if (value) {
              subscribe(dropTarget, handleDrop);
            } else {
              unsubscribe(dropTarget, handleDrop);
            }
            dropEnabled = value;
          }
        },
      },

      /**
       * Gets the event that will be raised when an error is encountered during drop processing.
       * @memberof viewerDragDropMixin.prototype
       * @type {Event}
       */
      dropError: {
        get: function () {
          return dropError;
        },
      },

      /**
       * Gets or sets a value indicating if existing data sources should be cleared before adding the newly dropped sources.
       * @memberof viewerDragDropMixin.prototype
       * @type {Boolean}
       */
      clearOnDrop: {
        get: function () {
          return clearOnDrop;
        },
        set: function (value) {
          clearOnDrop = value;
        },
      },

      /**
       * Gets or sets a value indicating if the camera should fly to the data source after it is loaded.
       * @memberof viewerDragDropMixin.prototype
       * @type {Boolean}
       */
      flyToOnDrop: {
        get: function () {
          return flyToOnDrop;
        },
        set: function (value) {
          flyToOnDrop = value;
        },
      },

      /**
       * Gets or sets the proxy to be used for KML.
       * @memberof viewerDragDropMixin.prototype
       * @type {Proxy}
       */
      proxy: {
        get: function () {
          return proxy;
        },
        set: function (value) {
          proxy = value;
        },
      },

      /**
       * Gets or sets a value indicating if the datasources should be clamped to the ground
       * @memberof viewerDragDropMixin.prototype
       * @type {Boolean}
       */
      clampToGround: {
        get: function () {
          return clampToGround;
        },
        set: function (value) {
          clampToGround = value;
        },
      },
    });

    function handleDrop(event) {
      stop(event);

      if (clearOnDrop) {
        viewer.entities.removeAll();
        viewer.dataSources.removeAll();
      }

      var files = event.dataTransfer.files;
      var length = files.length;
      for (var i = 0; i < length; i++) {
        var file = files[i];
        var reader = new FileReader();
        reader.onload = createOnLoadCallback(viewer, file, proxy, clampToGround);
        reader.onerror = createDropErrorCallback(viewer, file);
        reader.readAsText(file);
      }
    }

    //Enable drop by default;
    subscribe(dropTarget, handleDrop);

    //Wrap the destroy function to make sure all events are unsubscribed from
    viewer.destroy = wrapFunction(viewer, viewer.destroy, function () {
      viewer.dropEnabled = false;
    });

    //Specs need access to handleDrop
    viewer._handleDrop = handleDrop;
  }

  function stop(event) {
    event.stopPropagation();
    event.preventDefault();
  }

  function unsubscribe(dropTarget, handleDrop) {
    var currentTarget = dropTarget;
    if (defined(currentTarget)) {
      currentTarget.removeEventListener("drop", handleDrop, false);
      currentTarget.removeEventListener("dragenter", stop, false);
      currentTarget.removeEventListener("dragover", stop, false);
      currentTarget.removeEventListener("dragexit", stop, false);
    }
  }

  function subscribe(dropTarget, handleDrop) {
    dropTarget.addEventListener("drop", handleDrop, false);
    dropTarget.addEventListener("dragenter", stop, false);
    dropTarget.addEventListener("dragover", stop, false);
    dropTarget.addEventListener("dragexit", stop, false);
  }

  function createOnLoadCallback(viewer, file, proxy, clampToGround) {
    var scene = viewer.scene;
    return function (evt) {
      var fileName = file.name;
      try {
        var loadPromise;

        if (/\.czml$/i.test(fileName)) {
          loadPromise = CzmlDataSource.load(JSON.parse(evt.target.result), {
            sourceUri: fileName,
          });
        } else if (
          /\.geojson$/i.test(fileName) ||
          /\.json$/i.test(fileName) ||
          /\.topojson$/i.test(fileName)
        ) {
          loadPromise = GeoJsonDataSource.load(JSON.parse(evt.target.result), {
            sourceUri: fileName,
            clampToGround: clampToGround,
          });
        } else if (/\.(kml|kmz)$/i.test(fileName)) {
          loadPromise = KmlDataSource.load(file, {
            sourceUri: fileName,
            proxy: proxy,
            camera: scene.camera,
            canvas: scene.canvas,
            clampToGround: clampToGround,
          });
        } else {
          viewer.dropError.raiseEvent(
            viewer,
            fileName,
            "Unrecognized file: " + fileName
          );
          return;
        }

        if (defined(loadPromise)) {
          viewer.dataSources
            .add(loadPromise)
            .then(function (dataSource) {
              if (viewer.flyToOnDrop) {
                viewer.flyTo(dataSource);
              }
            })
            .otherwise(function (error) {
              viewer.dropError.raiseEvent(viewer, fileName, error);
            });
        }
      } catch (error) {
        viewer.dropError.raiseEvent(viewer, fileName, error);
      }
    };
  }

  function createDropErrorCallback(viewer, file) {
    return function (evt) {
      viewer.dropError.raiseEvent(viewer, file.name, evt.target.error);
    };
  }

  /**
   * A mixin which adds the {@link PerformanceWatchdog} widget to the {@link Viewer} widget.
   * Rather than being called directly, this function is normally passed as
   * a parameter to {@link Viewer#extend}, as shown in the example below.
   * @function
   *
   * @param {Viewer} viewer The viewer instance.
   * @param {Object} [options] An object with properties.
   * @param {String} [options.lowFrameRateMessage='This application appears to be performing poorly on your system.  Please try using a different web browser or updating your video drivers.'] The
   *        message to display when a low frame rate is detected.  The message is interpeted as HTML, so make sure
   *        it comes from a trusted source so that your application is not vulnerable to cross-site scripting attacks.
   *
   * @exception {DeveloperError} viewer is required.
   *
   * @example
   * var viewer = new Cesium.Viewer('cesiumContainer');
   * viewer.extend(Cesium.viewerPerformanceWatchdogMixin, {
   *     lowFrameRateMessage : 'Why is this going so <em>slowly</em>?'
   * });
   */
  function viewerPerformanceWatchdogMixin(viewer, options) {
    //>>includeStart('debug', pragmas.debug);
    if (!defined(viewer)) {
      throw new DeveloperError("viewer is required.");
    }
    //>>includeEnd('debug');

    options = defaultValue(options, defaultValue.EMPTY_OBJECT);

    var performanceWatchdog = new PerformanceWatchdog({
      scene: viewer.scene,
      container: viewer.bottomContainer,
      lowFrameRateMessage: options.lowFrameRateMessage,
    });

    Object.defineProperties(viewer, {
      performanceWatchdog: {
        get: function () {
          return performanceWatchdog;
        },
      },
    });
  }

  // createXXXGeometry functions may return Geometry or a Promise that resolves to Geometry
  // if the function requires access to ApproximateTerrainHeights.
  // For fully synchronous functions, just wrapping the function call in a `when` Promise doesn't
  // handle errors correctly, hence try-catch
  function callAndWrap(workerFunction, parameters, transferableObjects) {
    var resultOrPromise;
    try {
      resultOrPromise = workerFunction(parameters, transferableObjects);
      return resultOrPromise; // errors handled by Promise
    } catch (e) {
      return when.reject(e);
    }
  }

  /**
   * Creates an adapter function to allow a calculation function to operate as a Web Worker,
   * paired with TaskProcessor, to receive tasks and return results.
   *
   * @function createTaskProcessorWorker
   *
   * @param {createTaskProcessorWorker.WorkerFunction} workerFunction The calculation function,
   *        which takes parameters and returns a result.
   * @returns {createTaskProcessorWorker.TaskProcessorWorkerFunction} A function that adapts the
   *          calculation function to work as a Web Worker onmessage listener with TaskProcessor.
   *
   *
   * @example
   * function doCalculation(parameters, transferableObjects) {
   *   // calculate some result using the inputs in parameters
   *   return result;
   * }
   *
   * return Cesium.createTaskProcessorWorker(doCalculation);
   * // the resulting function is compatible with TaskProcessor
   *
   * @see TaskProcessor
   * @see {@link http://www.w3.org/TR/workers/|Web Workers}
   * @see {@link http://www.w3.org/TR/html5/common-dom-interfaces.html#transferable-objects|Transferable objects}
   */
  function createTaskProcessorWorker(workerFunction) {
    var postMessage;

    return function (event) {
      var data = event.data;

      var transferableObjects = [];
      var responseMessage = {
        id: data.id,
        result: undefined,
        error: undefined,
      };

      return when(
        callAndWrap(workerFunction, data.parameters, transferableObjects)
      )
        .then(function (result) {
          responseMessage.result = result;
        })
        .otherwise(function (e) {
          if (e instanceof Error) {
            // Errors can't be posted in a message, copy the properties
            responseMessage.error = {
              name: e.name,
              message: e.message,
              stack: e.stack,
            };
          } else {
            responseMessage.error = e;
          }
        })
        .always(function () {
          if (!defined(postMessage)) {
            postMessage = defaultValue(self.webkitPostMessage, self.postMessage);
          }

          if (!data.canTransferArrayBuffer) {
            transferableObjects.length = 0;
          }

          try {
            postMessage(responseMessage, transferableObjects);
          } catch (e) {
            // something went wrong trying to post the message, post a simpler
            // error that we can be sure will be cloneable
            responseMessage.result = undefined;
            responseMessage.error =
              "postMessage failed with error: " +
              formatError(e) +
              "\n  with responseMessage: " +
              JSON.stringify(responseMessage);
            postMessage(responseMessage);
          }
        });
    };
  }

  var VERSION = '1.72';

  exports.Animation = Animation;
  exports.AnimationViewModel = AnimationViewModel;
  exports.Appearance = Appearance;
  exports.ApproximateTerrainHeights = ApproximateTerrainHeights;
  exports.ArcGISTiledElevationTerrainProvider = ArcGISTiledElevationTerrainProvider;
  exports.ArcGisMapServerImageryProvider = ArcGisMapServerImageryProvider;
  exports.ArcType = ArcType$1;
  exports.AssociativeArray = AssociativeArray;
  exports.AttributeCompression = AttributeCompression;
  exports.AttributeType = AttributeType$1;
  exports.AutoExposure = AutoExposure;
  exports.Autolinker = Autolinker;
  exports.AutomaticUniforms = AutomaticUniforms;
  exports.Axis = Axis$1;
  exports.AxisAlignedBoundingBox = AxisAlignedBoundingBox;
  exports.BaseLayerPicker = BaseLayerPicker;
  exports.BaseLayerPickerViewModel = BaseLayerPickerViewModel;
  exports.BatchTable = BatchTable;
  exports.Batched3DModel3DTileContent = Batched3DModel3DTileContent;
  exports.Billboard = Billboard;
  exports.BillboardCollection = BillboardCollection;
  exports.BillboardGraphics = BillboardGraphics;
  exports.BillboardVisualizer = BillboardVisualizer;
  exports.BingMapsApi = BingMapsApi;
  exports.BingMapsGeocoderService = BingMapsGeocoderService;
  exports.BingMapsImageryProvider = BingMapsImageryProvider;
  exports.BingMapsStyle = BingMapsStyle$1;
  exports.BlendEquation = BlendEquation$1;
  exports.BlendFunction = BlendFunction$1;
  exports.BlendOption = BlendOption$1;
  exports.BlendingState = BlendingState$1;
  exports.BoundingRectangle = BoundingRectangle;
  exports.BoundingSphere = BoundingSphere;
  exports.BoundingSphereState = BoundingSphereState$1;
  exports.BoxEmitter = BoxEmitter;
  exports.BoxGeometry = BoxGeometry;
  exports.BoxGeometryUpdater = BoxGeometryUpdater;
  exports.BoxGraphics = BoxGraphics;
  exports.BoxOutlineGeometry = BoxOutlineGeometry;
  exports.BrdfLutGenerator = BrdfLutGenerator;
  exports.Buffer = Buffer$1;
  exports.BufferUsage = BufferUsage$1;
  exports.CallbackProperty = CallbackProperty;
  exports.Camera = Camera;
  exports.CameraEventAggregator = CameraEventAggregator;
  exports.CameraEventType = CameraEventType$1;
  exports.CameraFlightPath = CameraFlightPath;
  exports.Cartesian2 = Cartesian2;
  exports.Cartesian3 = Cartesian3;
  exports.Cartesian4 = Cartesian4;
  exports.Cartographic = Cartographic;
  exports.CartographicGeocoderService = CartographicGeocoderService;
  exports.CatmullRomSpline = CatmullRomSpline;
  exports.Cesium3DTile = Cesium3DTile;
  exports.Cesium3DTileBatchTable = Cesium3DTileBatchTable;
  exports.Cesium3DTileColorBlendMode = Cesium3DTileColorBlendMode$1;
  exports.Cesium3DTileContent = Cesium3DTileContent;
  exports.Cesium3DTileContentFactory = Cesium3DTileContentFactory;
  exports.Cesium3DTileContentState = Cesium3DTileContentState$1;
  exports.Cesium3DTileFeature = Cesium3DTileFeature;
  exports.Cesium3DTileFeatureTable = Cesium3DTileFeatureTable;
  exports.Cesium3DTileOptimizationHint = Cesium3DTileOptimizationHint$1;
  exports.Cesium3DTileOptimizations = Cesium3DTileOptimizations;
  exports.Cesium3DTilePass = Cesium3DTilePass$1;
  exports.Cesium3DTilePassState = Cesium3DTilePassState;
  exports.Cesium3DTilePointFeature = Cesium3DTilePointFeature;
  exports.Cesium3DTileRefine = Cesium3DTileRefine$1;
  exports.Cesium3DTileStyle = Cesium3DTileStyle;
  exports.Cesium3DTileStyleEngine = Cesium3DTileStyleEngine;
  exports.Cesium3DTilesInspector = Cesium3DTilesInspector;
  exports.Cesium3DTilesInspectorViewModel = Cesium3DTilesInspectorViewModel;
  exports.Cesium3DTileset = Cesium3DTileset;
  exports.Cesium3DTilesetCache = Cesium3DTilesetCache;
  exports.Cesium3DTilesetGraphics = Cesium3DTilesetGraphics;
  exports.Cesium3DTilesetHeatmap = Cesium3DTilesetHeatmap;
  exports.Cesium3DTilesetMostDetailedTraversal = Cesium3DTilesetMostDetailedTraversal;
  exports.Cesium3DTilesetStatistics = Cesium3DTilesetStatistics;
  exports.Cesium3DTilesetTraversal = Cesium3DTilesetTraversal;
  exports.Cesium3DTilesetVisualizer = Cesium3DTilesetVisualizer;
  exports.CesiumInspector = CesiumInspector;
  exports.CesiumInspectorViewModel = CesiumInspectorViewModel;
  exports.CesiumTerrainProvider = CesiumTerrainProvider;
  exports.CesiumWidget = CesiumWidget;
  exports.Check = Check;
  exports.CheckerboardMaterialProperty = CheckerboardMaterialProperty;
  exports.CircleEmitter = CircleEmitter;
  exports.CircleGeometry = CircleGeometry;
  exports.CircleOutlineGeometry = CircleOutlineGeometry;
  exports.ClassificationModel = ClassificationModel;
  exports.ClassificationPrimitive = ClassificationPrimitive;
  exports.ClassificationType = ClassificationType$1;
  exports.ClearCommand = ClearCommand;
  exports.ClippingPlane = ClippingPlane;
  exports.ClippingPlaneCollection = ClippingPlaneCollection;
  exports.Clock = Clock;
  exports.ClockRange = ClockRange$1;
  exports.ClockStep = ClockStep$1;
  exports.ClockViewModel = ClockViewModel;
  exports.Color = Color;
  exports.ColorBlendMode = ColorBlendMode$1;
  exports.ColorGeometryInstanceAttribute = ColorGeometryInstanceAttribute;
  exports.ColorMaterialProperty = ColorMaterialProperty;
  exports.Command = Command;
  exports.ComponentDatatype = ComponentDatatype$1;
  exports.Composite3DTileContent = Composite3DTileContent;
  exports.CompositeEntityCollection = CompositeEntityCollection;
  exports.CompositeMaterialProperty = CompositeMaterialProperty;
  exports.CompositePositionProperty = CompositePositionProperty;
  exports.CompositeProperty = CompositeProperty;
  exports.CompressedTextureBuffer = CompressedTextureBuffer;
  exports.ComputeCommand = ComputeCommand;
  exports.ComputeEngine = ComputeEngine;
  exports.ConditionsExpression = ConditionsExpression;
  exports.ConeEmitter = ConeEmitter;
  exports.ConstantPositionProperty = ConstantPositionProperty;
  exports.ConstantProperty = ConstantProperty;
  exports.Context = Context;
  exports.ContextLimits = ContextLimits;
  exports.CoplanarPolygonGeometry = CoplanarPolygonGeometry;
  exports.CoplanarPolygonGeometryLibrary = CoplanarPolygonGeometryLibrary;
  exports.CoplanarPolygonOutlineGeometry = CoplanarPolygonOutlineGeometry;
  exports.CornerType = CornerType$1;
  exports.CorridorGeometry = CorridorGeometry;
  exports.CorridorGeometryLibrary = CorridorGeometryLibrary;
  exports.CorridorGeometryUpdater = CorridorGeometryUpdater;
  exports.CorridorGraphics = CorridorGraphics;
  exports.CorridorOutlineGeometry = CorridorOutlineGeometry;
  exports.Credit = Credit;
  exports.CreditDisplay = CreditDisplay;
  exports.CubeMap = CubeMap;
  exports.CubeMapFace = CubeMapFace;
  exports.CubicRealPolynomial = CubicRealPolynomial;
  exports.CullFace = CullFace$1;
  exports.CullingVolume = CullingVolume;
  exports.CustomDataSource = CustomDataSource;
  exports.CylinderGeometry = CylinderGeometry;
  exports.CylinderGeometryLibrary = CylinderGeometryLibrary;
  exports.CylinderGeometryUpdater = CylinderGeometryUpdater;
  exports.CylinderGraphics = CylinderGraphics;
  exports.CylinderOutlineGeometry = CylinderOutlineGeometry;
  exports.CzmlDataSource = CzmlDataSource;
  exports.DataSource = DataSource;
  exports.DataSourceClock = DataSourceClock;
  exports.DataSourceCollection = DataSourceCollection;
  exports.DataSourceDisplay = DataSourceDisplay;
  exports.DebugAppearance = DebugAppearance;
  exports.DebugCameraPrimitive = DebugCameraPrimitive;
  exports.DebugInspector = DebugInspector;
  exports.DebugModelMatrixPrimitive = DebugModelMatrixPrimitive;
  exports.DefaultProxy = DefaultProxy;
  exports.DepthFunction = DepthFunction$1;
  exports.DepthPlane = DepthPlane;
  exports.DerivedCommand = DerivedCommand;
  exports.DeveloperError = DeveloperError;
  exports.DeviceOrientationCameraController = DeviceOrientationCameraController;
  exports.DirectionalLight = DirectionalLight;
  exports.DiscardEmptyTileImagePolicy = DiscardEmptyTileImagePolicy;
  exports.DiscardMissingTileImagePolicy = DiscardMissingTileImagePolicy;
  exports.DistanceDisplayCondition = DistanceDisplayCondition;
  exports.DistanceDisplayConditionGeometryInstanceAttribute = DistanceDisplayConditionGeometryInstanceAttribute;
  exports.DoublyLinkedList = DoublyLinkedList;
  exports.DracoLoader = DracoLoader;
  exports.DrawCommand = DrawCommand;
  exports.DynamicGeometryBatch = DynamicGeometryBatch;
  exports.DynamicGeometryUpdater = DynamicGeometryUpdater;
  exports.EarthOrientationParameters = EarthOrientationParameters;
  exports.EarthOrientationParametersSample = EarthOrientationParametersSample;
  exports.EasingFunction = EasingFunction$1;
  exports.EllipseGeometry = EllipseGeometry;
  exports.EllipseGeometryLibrary = EllipseGeometryLibrary;
  exports.EllipseGeometryUpdater = EllipseGeometryUpdater;
  exports.EllipseGraphics = EllipseGraphics;
  exports.EllipseOutlineGeometry = EllipseOutlineGeometry;
  exports.Ellipsoid = Ellipsoid;
  exports.EllipsoidGeodesic = EllipsoidGeodesic;
  exports.EllipsoidGeometry = EllipsoidGeometry;
  exports.EllipsoidGeometryUpdater = EllipsoidGeometryUpdater;
  exports.EllipsoidGraphics = EllipsoidGraphics;
  exports.EllipsoidOutlineGeometry = EllipsoidOutlineGeometry;
  exports.EllipsoidPrimitive = EllipsoidPrimitive;
  exports.EllipsoidRhumbLine = EllipsoidRhumbLine;
  exports.EllipsoidSurfaceAppearance = EllipsoidSurfaceAppearance;
  exports.EllipsoidTangentPlane = EllipsoidTangentPlane;
  exports.EllipsoidTerrainProvider = EllipsoidTerrainProvider;
  exports.EllipsoidalOccluder = EllipsoidalOccluder;
  exports.Empty3DTileContent = Empty3DTileContent;
  exports.EncodedCartesian3 = EncodedCartesian3;
  exports.Entity = Entity;
  exports.EntityCluster = EntityCluster;
  exports.EntityCollection = EntityCollection;
  exports.EntityView = EntityView;
  exports.Event = Event;
  exports.EventHelper = EventHelper;
  exports.Expression = Expression;
  exports.ExpressionNodeType = ExpressionNodeType$1;
  exports.ExtrapolationType = ExtrapolationType$1;
  exports.FXAA3_11 = FXAA3_11;
  exports.FeatureDetection = FeatureDetection;
  exports.Fog = Fog;
  exports.ForEach = ForEach;
  exports.FrameRateMonitor = FrameRateMonitor;
  exports.FrameState = FrameState;
  exports.Framebuffer = Framebuffer;
  exports.FrustumCommands = FrustumCommands;
  exports.FrustumGeometry = FrustumGeometry;
  exports.FrustumOutlineGeometry = FrustumOutlineGeometry;
  exports.Fullscreen = Fullscreen;
  exports.FullscreenButton = FullscreenButton;
  exports.FullscreenButtonViewModel = FullscreenButtonViewModel;
  exports.GeoJsonDataSource = GeoJsonDataSource;
  exports.GeocodeType = GeocodeType$1;
  exports.Geocoder = Geocoder;
  exports.GeocoderService = GeocoderService;
  exports.GeocoderViewModel = GeocoderViewModel;
  exports.GeographicProjection = GeographicProjection;
  exports.GeographicTilingScheme = GeographicTilingScheme;
  exports.Geometry = Geometry;
  exports.Geometry3DTileContent = Geometry3DTileContent;
  exports.GeometryAttribute = GeometryAttribute;
  exports.GeometryAttributes = GeometryAttributes;
  exports.GeometryFactory = GeometryFactory;
  exports.GeometryInstance = GeometryInstance;
  exports.GeometryInstanceAttribute = GeometryInstanceAttribute;
  exports.GeometryOffsetAttribute = GeometryOffsetAttribute$1;
  exports.GeometryPipeline = GeometryPipeline;
  exports.GeometryType = GeometryType$1;
  exports.GeometryUpdater = GeometryUpdater;
  exports.GeometryVisualizer = GeometryVisualizer;
  exports.GetFeatureInfoFormat = GetFeatureInfoFormat;
  exports.Globe = Globe;
  exports.GlobeDepth = GlobeDepth;
  exports.GlobeSurfaceShaderSet = GlobeSurfaceShaderSet;
  exports.GlobeSurfaceTile = GlobeSurfaceTile;
  exports.GlobeSurfaceTileProvider = GlobeSurfaceTileProvider;
  exports.GlobeTranslucency = GlobeTranslucency;
  exports.GlobeTranslucencyFramebuffer = GlobeTranslucencyFramebuffer;
  exports.GlobeTranslucencyState = GlobeTranslucencyState;
  exports.GoogleEarthEnterpriseImageryProvider = GoogleEarthEnterpriseImageryProvider;
  exports.GoogleEarthEnterpriseMapsProvider = GoogleEarthEnterpriseMapsProvider;
  exports.GoogleEarthEnterpriseMetadata = GoogleEarthEnterpriseMetadata;
  exports.GoogleEarthEnterpriseTerrainData = GoogleEarthEnterpriseTerrainData;
  exports.GoogleEarthEnterpriseTerrainProvider = GoogleEarthEnterpriseTerrainProvider;
  exports.GoogleEarthEnterpriseTileInformation = GoogleEarthEnterpriseTileInformation;
  exports.GregorianDate = GregorianDate;
  exports.GridImageryProvider = GridImageryProvider;
  exports.GridMaterialProperty = GridMaterialProperty;
  exports.GroundGeometryUpdater = GroundGeometryUpdater;
  exports.GroundPolylineGeometry = GroundPolylineGeometry;
  exports.GroundPolylinePrimitive = GroundPolylinePrimitive;
  exports.GroundPrimitive = GroundPrimitive;
  exports.HeadingPitchRange = HeadingPitchRange;
  exports.HeadingPitchRoll = HeadingPitchRoll;
  exports.Heap = Heap;
  exports.HeightReference = HeightReference$1;
  exports.HeightmapEncoding = HeightmapEncoding$1;
  exports.HeightmapTerrainData = HeightmapTerrainData;
  exports.HeightmapTessellator = HeightmapTessellator;
  exports.HermitePolynomialApproximation = HermitePolynomialApproximation;
  exports.HermiteSpline = HermiteSpline;
  exports.HomeButton = HomeButton;
  exports.HomeButtonViewModel = HomeButtonViewModel;
  exports.HorizontalOrigin = HorizontalOrigin$1;
  exports.Iau2000Orientation = Iau2000Orientation;
  exports.Iau2006XysData = Iau2006XysData;
  exports.Iau2006XysSample = Iau2006XysSample;
  exports.IauOrientationAxes = IauOrientationAxes;
  exports.IauOrientationParameters = IauOrientationParameters;
  exports.ImageMaterialProperty = ImageMaterialProperty;
  exports.Imagery = Imagery;
  exports.ImageryLayer = ImageryLayer;
  exports.ImageryLayerCollection = ImageryLayerCollection;
  exports.ImageryLayerFeatureInfo = ImageryLayerFeatureInfo;
  exports.ImageryProvider = ImageryProvider;
  exports.ImagerySplitDirection = ImagerySplitDirection$1;
  exports.ImageryState = ImageryState$1;
  exports.IndexDatatype = IndexDatatype$1;
  exports.InfoBox = InfoBox;
  exports.InfoBoxViewModel = InfoBoxViewModel;
  exports.InspectorShared = InspectorShared;
  exports.Instanced3DModel3DTileContent = Instanced3DModel3DTileContent;
  exports.InterpolationAlgorithm = InterpolationAlgorithm;
  exports.Intersect = Intersect$1;
  exports.IntersectionTests = IntersectionTests;
  exports.Intersections2D = Intersections2D;
  exports.Interval = Interval;
  exports.InvertClassification = InvertClassification;
  exports.Ion = Ion;
  exports.IonGeocoderService = IonGeocoderService;
  exports.IonImageryProvider = IonImageryProvider;
  exports.IonResource = IonResource;
  exports.IonWorldImageryStyle = IonWorldImageryStyle$1;
  exports.Iso8601 = Iso8601;
  exports.JobScheduler = JobScheduler;
  exports.JobType = JobType$1;
  exports.JulianDate = JulianDate;
  exports.KeyboardEventModifier = KeyboardEventModifier$1;
  exports.KmlCamera = KmlCamera;
  exports.KmlDataSource = KmlDataSource;
  exports.KmlLookAt = KmlLookAt;
  exports.KmlTour = KmlTour;
  exports.KmlTourFlyTo = KmlTourFlyTo;
  exports.KmlTourWait = KmlTourWait;
  exports.Label = Label;
  exports.LabelCollection = LabelCollection;
  exports.LabelGraphics = LabelGraphics;
  exports.LabelStyle = LabelStyle$1;
  exports.LabelVisualizer = LabelVisualizer;
  exports.LagrangePolynomialApproximation = LagrangePolynomialApproximation;
  exports.LeapSecond = LeapSecond;
  exports.LercDecode = LercDecode;
  exports.Light = Light;
  exports.LinearApproximation = LinearApproximation;
  exports.LinearSpline = LinearSpline;
  exports.ManagedArray = ManagedArray;
  exports.MapMode2D = MapMode2D$1;
  exports.MapProjection = MapProjection;
  exports.MapboxApi = MapboxApi;
  exports.MapboxImageryProvider = MapboxImageryProvider;
  exports.MapboxStyleImageryProvider = MapboxStyleImageryProvider;
  exports.Material = Material;
  exports.MaterialAppearance = MaterialAppearance;
  exports.MaterialProperty = MaterialProperty;
  exports.Math = CesiumMath;
  exports.Matrix2 = Matrix2;
  exports.Matrix3 = Matrix3;
  exports.Matrix4 = Matrix4;
  exports.MipmapHint = MipmapHint$1;
  exports.Model = Model;
  exports.ModelAnimation = ModelAnimation;
  exports.ModelAnimationCache = ModelAnimationCache;
  exports.ModelAnimationCollection = ModelAnimationCollection;
  exports.ModelAnimationLoop = ModelAnimationLoop$1;
  exports.ModelAnimationState = ModelAnimationState;
  exports.ModelGraphics = ModelGraphics;
  exports.ModelInstance = ModelInstance;
  exports.ModelInstanceCollection = ModelInstanceCollection;
  exports.ModelLoadResources = ModelLoadResources;
  exports.ModelMaterial = ModelMaterial;
  exports.ModelMesh = ModelMesh;
  exports.ModelNode = ModelNode;
  exports.ModelOutlineLoader = ModelOutlineLoader;
  exports.ModelUtility = ModelUtility;
  exports.ModelVisualizer = ModelVisualizer;
  exports.Moon = Moon;
  exports.NavigationHelpButton = NavigationHelpButton;
  exports.NavigationHelpButtonViewModel = NavigationHelpButtonViewModel;
  exports.NearFarScalar = NearFarScalar;
  exports.NeverTileDiscardPolicy = NeverTileDiscardPolicy;
  exports.NoSleep = NoSleep;
  exports.NodeTransformationProperty = NodeTransformationProperty;
  exports.OIT = OIT;
  exports.Occluder = Occluder;
  exports.OctahedralProjectedCubeMap = OctahedralProjectedCubeMap;
  exports.OffsetGeometryInstanceAttribute = OffsetGeometryInstanceAttribute;
  exports.OpenCageGeocoderService = OpenCageGeocoderService;
  exports.OpenStreetMapImageryProvider = OpenStreetMapImageryProvider;
  exports.OrderedGroundPrimitiveCollection = OrderedGroundPrimitiveCollection;
  exports.OrientedBoundingBox = OrientedBoundingBox;
  exports.OrthographicFrustum = OrthographicFrustum;
  exports.OrthographicOffCenterFrustum = OrthographicOffCenterFrustum;
  exports.Packable = Packable;
  exports.PackableForInterpolation = PackableForInterpolation;
  exports.Particle = Particle;
  exports.ParticleBurst = ParticleBurst;
  exports.ParticleEmitter = ParticleEmitter;
  exports.ParticleSystem = ParticleSystem;
  exports.Pass = Pass$1;
  exports.PassState = PassState;
  exports.PathGraphics = PathGraphics;
  exports.PathVisualizer = PathVisualizer;
  exports.PeliasGeocoderService = PeliasGeocoderService;
  exports.PerInstanceColorAppearance = PerInstanceColorAppearance;
  exports.PerformanceDisplay = PerformanceDisplay;
  exports.PerformanceWatchdog = PerformanceWatchdog;
  exports.PerformanceWatchdogViewModel = PerformanceWatchdogViewModel;
  exports.PerspectiveFrustum = PerspectiveFrustum;
  exports.PerspectiveOffCenterFrustum = PerspectiveOffCenterFrustum;
  exports.PickDepth = PickDepth;
  exports.PickDepthFramebuffer = PickDepthFramebuffer;
  exports.PickFramebuffer = PickFramebuffer;
  exports.Picking = Picking;
  exports.PinBuilder = PinBuilder;
  exports.PixelDatatype = PixelDatatype$1;
  exports.PixelFormat = PixelFormat$1;
  exports.Plane = Plane;
  exports.PlaneGeometry = PlaneGeometry;
  exports.PlaneGeometryUpdater = PlaneGeometryUpdater;
  exports.PlaneGraphics = PlaneGraphics;
  exports.PlaneOutlineGeometry = PlaneOutlineGeometry;
  exports.PointCloud = PointCloud;
  exports.PointCloud3DTileContent = PointCloud3DTileContent;
  exports.PointCloudEyeDomeLighting = PointCloudEyeDomeLighting;
  exports.PointCloudShading = PointCloudShading;
  exports.PointGraphics = PointGraphics;
  exports.PointPrimitive = PointPrimitive;
  exports.PointPrimitiveCollection = PointPrimitiveCollection;
  exports.PointVisualizer = PointVisualizer;
  exports.PolygonGeometry = PolygonGeometry;
  exports.PolygonGeometryLibrary = PolygonGeometryLibrary;
  exports.PolygonGeometryUpdater = PolygonGeometryUpdater;
  exports.PolygonGraphics = PolygonGraphics;
  exports.PolygonHierarchy = PolygonHierarchy;
  exports.PolygonOutlineGeometry = PolygonOutlineGeometry;
  exports.PolygonPipeline = PolygonPipeline;
  exports.Polyline = Polyline;
  exports.PolylineArrowMaterialProperty = PolylineArrowMaterialProperty;
  exports.PolylineCollection = PolylineCollection;
  exports.PolylineColorAppearance = PolylineColorAppearance;
  exports.PolylineDashMaterialProperty = PolylineDashMaterialProperty;
  exports.PolylineGeometry = PolylineGeometry;
  exports.PolylineGeometryUpdater = PolylineGeometryUpdater;
  exports.PolylineGlowMaterialProperty = PolylineGlowMaterialProperty;
  exports.PolylineGraphics = PolylineGraphics;
  exports.PolylineMaterialAppearance = PolylineMaterialAppearance;
  exports.PolylineOutlineMaterialProperty = PolylineOutlineMaterialProperty;
  exports.PolylinePipeline = PolylinePipeline;
  exports.PolylineVisualizer = PolylineVisualizer;
  exports.PolylineVolumeGeometry = PolylineVolumeGeometry;
  exports.PolylineVolumeGeometryLibrary = PolylineVolumeGeometryLibrary;
  exports.PolylineVolumeGeometryUpdater = PolylineVolumeGeometryUpdater;
  exports.PolylineVolumeGraphics = PolylineVolumeGraphics;
  exports.PolylineVolumeOutlineGeometry = PolylineVolumeOutlineGeometry;
  exports.PositionProperty = PositionProperty;
  exports.PositionPropertyArray = PositionPropertyArray;
  exports.PostProcessStage = PostProcessStage;
  exports.PostProcessStageCollection = PostProcessStageCollection;
  exports.PostProcessStageComposite = PostProcessStageComposite;
  exports.PostProcessStageLibrary = PostProcessStageLibrary;
  exports.PostProcessStageSampleMode = PostProcessStageSampleMode;
  exports.PostProcessStageTextureCache = PostProcessStageTextureCache;
  exports.Primitive = Primitive;
  exports.PrimitiveCollection = PrimitiveCollection;
  exports.PrimitivePipeline = PrimitivePipeline;
  exports.PrimitiveState = PrimitiveState$1;
  exports.PrimitiveType = PrimitiveType$1;
  exports.ProjectionPicker = ProjectionPicker;
  exports.ProjectionPickerViewModel = ProjectionPickerViewModel;
  exports.Property = Property;
  exports.PropertyArray = PropertyArray;
  exports.PropertyBag = PropertyBag;
  exports.ProviderViewModel = ProviderViewModel;
  exports.Proxy = Proxy;
  exports.QuadraticRealPolynomial = QuadraticRealPolynomial;
  exports.QuadtreeOccluders = QuadtreeOccluders;
  exports.QuadtreePrimitive = QuadtreePrimitive;
  exports.QuadtreeTile = QuadtreeTile;
  exports.QuadtreeTileLoadState = QuadtreeTileLoadState$1;
  exports.QuadtreeTileProvider = QuadtreeTileProvider;
  exports.QuantizedMeshTerrainData = QuantizedMeshTerrainData;
  exports.QuarticRealPolynomial = QuarticRealPolynomial;
  exports.Quaternion = Quaternion;
  exports.QuaternionSpline = QuaternionSpline;
  exports.Queue = Queue;
  exports.Ray = Ray;
  exports.Rectangle = Rectangle;
  exports.RectangleCollisionChecker = RectangleCollisionChecker;
  exports.RectangleGeometry = RectangleGeometry;
  exports.RectangleGeometryLibrary = RectangleGeometryLibrary;
  exports.RectangleGeometryUpdater = RectangleGeometryUpdater;
  exports.RectangleGraphics = RectangleGraphics;
  exports.RectangleOutlineGeometry = RectangleOutlineGeometry;
  exports.ReferenceFrame = ReferenceFrame$1;
  exports.ReferenceProperty = ReferenceProperty;
  exports.RenderState = RenderState;
  exports.Renderbuffer = Renderbuffer;
  exports.RenderbufferFormat = RenderbufferFormat$1;
  exports.Request = Request;
  exports.RequestErrorEvent = RequestErrorEvent;
  exports.RequestScheduler = RequestScheduler;
  exports.RequestState = RequestState$1;
  exports.RequestType = RequestType$1;
  exports.Resource = Resource;
  exports.Rotation = Rotation;
  exports.RuntimeError = RuntimeError;
  exports.SDFSettings = SDFSettings$1;
  exports.SampledPositionProperty = SampledPositionProperty;
  exports.SampledProperty = SampledProperty;
  exports.Sampler = Sampler;
  exports.ScaledPositionProperty = ScaledPositionProperty;
  exports.Scene = Scene;
  exports.SceneFramebuffer = SceneFramebuffer;
  exports.SceneMode = SceneMode$1;
  exports.SceneModePicker = SceneModePicker;
  exports.SceneModePickerViewModel = SceneModePickerViewModel;
  exports.SceneTransforms = SceneTransforms;
  exports.SceneTransitioner = SceneTransitioner;
  exports.ScreenSpaceCameraController = ScreenSpaceCameraController;
  exports.ScreenSpaceEventHandler = ScreenSpaceEventHandler;
  exports.ScreenSpaceEventType = ScreenSpaceEventType$1;
  exports.SelectionIndicator = SelectionIndicator;
  exports.SelectionIndicatorViewModel = SelectionIndicatorViewModel;
  exports.ShaderCache = ShaderCache;
  exports.ShaderProgram = ShaderProgram;
  exports.ShaderSource = ShaderSource;
  exports.ShadowMap = ShadowMap;
  exports.ShadowMapShader = ShadowMapShader;
  exports.ShadowMode = ShadowMode$1;
  exports.ShadowVolumeAppearance = ShadowVolumeAppearance;
  exports.ShowGeometryInstanceAttribute = ShowGeometryInstanceAttribute;
  exports.Simon1994PlanetaryPositions = Simon1994PlanetaryPositions;
  exports.SimplePolylineGeometry = SimplePolylineGeometry;
  exports.SingleTileImageryProvider = SingleTileImageryProvider;
  exports.SkyAtmosphere = SkyAtmosphere;
  exports.SkyBox = SkyBox;
  exports.SphereEmitter = SphereEmitter;
  exports.SphereGeometry = SphereGeometry;
  exports.SphereOutlineGeometry = SphereOutlineGeometry;
  exports.Spherical = Spherical;
  exports.Spline = Spline;
  exports.StaticGeometryColorBatch = StaticGeometryColorBatch;
  exports.StaticGeometryPerMaterialBatch = StaticGeometryPerMaterialBatch;
  exports.StaticGroundGeometryColorBatch = StaticGroundGeometryColorBatch;
  exports.StaticGroundGeometryPerMaterialBatch = StaticGroundGeometryPerMaterialBatch;
  exports.StaticGroundPolylinePerMaterialBatch = StaticGroundPolylinePerMaterialBatch;
  exports.StaticOutlineGeometryBatch = StaticOutlineGeometryBatch;
  exports.StencilConstants = StencilConstants$1;
  exports.StencilFunction = StencilFunction$1;
  exports.StencilOperation = StencilOperation$1;
  exports.StripeMaterialProperty = StripeMaterialProperty;
  exports.StripeOrientation = StripeOrientation$1;
  exports.StyleExpression = StyleExpression;
  exports.Sun = Sun;
  exports.SunLight = SunLight;
  exports.SunPostProcess = SunPostProcess;
  exports.SvgPathBindingHandler = SvgPathBindingHandler;
  exports.TaskProcessor = TaskProcessor;
  exports.TerrainData = TerrainData;
  exports.TerrainEncoding = TerrainEncoding;
  exports.TerrainFillMesh = TerrainFillMesh;
  exports.TerrainMesh = TerrainMesh;
  exports.TerrainOffsetProperty = TerrainOffsetProperty;
  exports.TerrainProvider = TerrainProvider;
  exports.TerrainQuantization = TerrainQuantization$1;
  exports.TerrainState = TerrainState$2;
  exports.Texture = Texture;
  exports.TextureAtlas = TextureAtlas;
  exports.TextureCache = TextureCache;
  exports.TextureMagnificationFilter = TextureMagnificationFilter$1;
  exports.TextureMinificationFilter = TextureMinificationFilter$1;
  exports.TextureWrap = TextureWrap$1;
  exports.TileAvailability = TileAvailability;
  exports.TileBoundingRegion = TileBoundingRegion;
  exports.TileBoundingSphere = TileBoundingSphere;
  exports.TileBoundingVolume = TileBoundingVolume;
  exports.TileCoordinatesImageryProvider = TileCoordinatesImageryProvider;
  exports.TileDiscardPolicy = TileDiscardPolicy;
  exports.TileEdge = TileEdge;
  exports.TileImagery = TileImagery;
  exports.TileMapServiceImageryProvider = TileMapServiceImageryProvider;
  exports.TileOrientedBoundingBox = TileOrientedBoundingBox;
  exports.TileProviderError = TileProviderError;
  exports.TileReplacementQueue = TileReplacementQueue;
  exports.TileSelectionResult = TileSelectionResult;
  exports.TileState = TileState$1;
  exports.Tileset3DTileContent = Tileset3DTileContent;
  exports.TilingScheme = TilingScheme;
  exports.TimeConstants = TimeConstants$1;
  exports.TimeDynamicImagery = TimeDynamicImagery;
  exports.TimeDynamicPointCloud = TimeDynamicPointCloud;
  exports.TimeInterval = TimeInterval;
  exports.TimeIntervalCollection = TimeIntervalCollection;
  exports.TimeIntervalCollectionPositionProperty = TimeIntervalCollectionPositionProperty;
  exports.TimeIntervalCollectionProperty = TimeIntervalCollectionProperty;
  exports.TimeStandard = TimeStandard$1;
  exports.Timeline = Timeline;
  exports.TimelineHighlightRange = TimelineHighlightRange;
  exports.TimelineTrack = TimelineTrack;
  exports.Tipsify = Tipsify;
  exports.ToggleButtonViewModel = ToggleButtonViewModel;
  exports.Tonemapper = Tonemapper$1;
  exports.Transforms = Transforms;
  exports.TranslationRotationScale = TranslationRotationScale;
  exports.TridiagonalSystemSolver = TridiagonalSystemSolver;
  exports.TrustedServers = TrustedServers;
  exports.Tween = TWEEN;
  exports.TweenCollection = TweenCollection;
  exports.UniformState = UniformState;
  exports.Uri = URI;
  exports.UrlTemplateImageryProvider = UrlTemplateImageryProvider;
  exports.VERSION = VERSION;
  exports.VRButton = VRButton;
  exports.VRButtonViewModel = VRButtonViewModel;
  exports.VRTheWorldTerrainProvider = VRTheWorldTerrainProvider;
  exports.Vector3DTileBatch = Vector3DTileBatch;
  exports.Vector3DTileContent = Vector3DTileContent;
  exports.Vector3DTileGeometry = Vector3DTileGeometry;
  exports.Vector3DTilePoints = Vector3DTilePoints;
  exports.Vector3DTilePolygons = Vector3DTilePolygons;
  exports.Vector3DTilePolylines = Vector3DTilePolylines;
  exports.Vector3DTilePrimitive = Vector3DTilePrimitive;
  exports.VelocityOrientationProperty = VelocityOrientationProperty;
  exports.VelocityVectorProperty = VelocityVectorProperty;
  exports.VertexArray = VertexArray;
  exports.VertexArrayFacade = VertexArrayFacade;
  exports.VertexFormat = VertexFormat;
  exports.VerticalOrigin = VerticalOrigin$1;
  exports.VideoSynchronizer = VideoSynchronizer;
  exports.View = View;
  exports.Viewer = Viewer;
  exports.ViewportQuad = ViewportQuad;
  exports.Visibility = Visibility$1;
  exports.Visualizer = Visualizer;
  exports.WallGeometry = WallGeometry;
  exports.WallGeometryLibrary = WallGeometryLibrary;
  exports.WallGeometryUpdater = WallGeometryUpdater;
  exports.WallGraphics = WallGraphics;
  exports.WallOutlineGeometry = WallOutlineGeometry;
  exports.WebGLConstants = WebGLConstants$1;
  exports.WebMapServiceImageryProvider = WebMapServiceImageryProvider;
  exports.WebMapTileServiceImageryProvider = WebMapTileServiceImageryProvider;
  exports.WebMercatorProjection = WebMercatorProjection;
  exports.WebMercatorTilingScheme = WebMercatorTilingScheme;
  exports.WeightSpline = WeightSpline;
  exports.WindingOrder = WindingOrder$1;
  exports._shadersAcesTonemappingStage = AcesTonemapping;
  exports._shadersAdditiveBlend = AdditiveBlend;
  exports._shadersAdjustTranslucentFS = AdjustTranslucentFS;
  exports._shadersAllMaterialAppearanceFS = AllMaterialAppearanceFS;
  exports._shadersAllMaterialAppearanceVS = AllMaterialAppearanceVS;
  exports._shadersAmbientOcclusionGenerate = AmbientOcclusionGenerate;
  exports._shadersAmbientOcclusionModulate = AmbientOcclusionModulate;
  exports._shadersAspectRampMaterial = AspectRampMaterial;
  exports._shadersBasicMaterialAppearanceFS = BasicMaterialAppearanceFS;
  exports._shadersBasicMaterialAppearanceVS = BasicMaterialAppearanceVS;
  exports._shadersBillboardCollectionFS = BillboardCollectionFS;
  exports._shadersBillboardCollectionVS = BillboardCollectionVS;
  exports._shadersBlackAndWhite = BlackAndWhite;
  exports._shadersBloomComposite = BloomComposite;
  exports._shadersBrdfLutGeneratorFS = BrdfLutGeneratorFS;
  exports._shadersBrightPass = BrightPass;
  exports._shadersBrightness = Brightness;
  exports._shadersBumpMapMaterial = BumpMapMaterial;
  exports._shadersCheckerboardMaterial = CheckerboardMaterial;
  exports._shadersCompositeOITFS = CompositeOITFS;
  exports._shadersContrastBias = ContrastBias;
  exports._shadersCzmBuiltins = CzmBuiltins;
  exports._shadersDepthOfField = DepthOfField;
  exports._shadersDepthPlaneFS = DepthPlaneFS;
  exports._shadersDepthPlaneVS = DepthPlaneVS;
  exports._shadersDepthView = DepthView;
  exports._shadersDepthViewPacked = DepthViewPacked;
  exports._shadersDotMaterial = DotMaterial;
  exports._shadersEdgeDetection = EdgeDetection;
  exports._shadersElevationContourMaterial = ElevationContourMaterial;
  exports._shadersElevationRampMaterial = ElevationRampMaterial;
  exports._shadersEllipsoidFS = EllipsoidFS;
  exports._shadersEllipsoidSurfaceAppearanceFS = EllipsoidSurfaceAppearanceFS;
  exports._shadersEllipsoidSurfaceAppearanceVS = EllipsoidSurfaceAppearanceVS;
  exports._shadersEllipsoidVS = EllipsoidVS;
  exports._shadersFXAA = FXAA;
  exports._shadersFadeMaterial = FadeMaterial;
  exports._shadersFilmicTonemapping = FilmicTonemapping;
  exports._shadersGaussianBlur1D = GaussianBlur1D;
  exports._shadersGlobeFS = GlobeFS;
  exports._shadersGlobeVS = GlobeVS;
  exports._shadersGridMaterial = GridMaterial;
  exports._shadersGroundAtmosphere = GroundAtmosphere;
  exports._shadersHSBToRGB = czm_HSBToRGB;
  exports._shadersHSLToRGB = czm_HSLToRGB;
  exports._shadersLensFlare = LensFlare;
  exports._shadersModifiedReinhardTonemapping = ModifiedReinhardTonemapping;
  exports._shadersNightVision = NightVision;
  exports._shadersNormalMapMaterial = NormalMapMaterial;
  exports._shadersOctahedralProjectionAtlasFS = OctahedralProjectionAtlasFS;
  exports._shadersOctahedralProjectionFS = OctahedralProjectionFS;
  exports._shadersOctahedralProjectionVS = OctahedralProjectionVS;
  exports._shadersPassThrough = PassThrough;
  exports._shadersPassThroughDepth = PassThroughDepth;
  exports._shadersPerInstanceColorAppearanceFS = PerInstanceColorAppearanceFS;
  exports._shadersPerInstanceColorAppearanceVS = PerInstanceColorAppearanceVS;
  exports._shadersPerInstanceFlatColorAppearanceFS = PerInstanceFlatColorAppearanceFS;
  exports._shadersPerInstanceFlatColorAppearanceVS = PerInstanceFlatColorAppearanceVS;
  exports._shadersPointCloudEyeDomeLighting = PointCloudEyeDomeLightingShader;
  exports._shadersPointPrimitiveCollectionFS = PointPrimitiveCollectionFS;
  exports._shadersPointPrimitiveCollectionVS = PointPrimitiveCollectionVS;
  exports._shadersPolylineArrowMaterial = PolylineArrowMaterial;
  exports._shadersPolylineColorAppearanceVS = PolylineColorAppearanceVS;
  exports._shadersPolylineCommon = PolylineCommon;
  exports._shadersPolylineDashMaterial = PolylineDashMaterial;
  exports._shadersPolylineFS = PolylineFS;
  exports._shadersPolylineGlowMaterial = PolylineGlowMaterial;
  exports._shadersPolylineMaterialAppearanceVS = PolylineMaterialAppearanceVS;
  exports._shadersPolylineOutlineMaterial = PolylineOutlineMaterial;
  exports._shadersPolylineShadowVolumeFS = PolylineShadowVolumeFS;
  exports._shadersPolylineShadowVolumeMorphFS = PolylineShadowVolumeMorphFS;
  exports._shadersPolylineShadowVolumeMorphVS = PolylineShadowVolumeMorphVS;
  exports._shadersPolylineShadowVolumeVS = PolylineShadowVolumeVS;
  exports._shadersPolylineVS = PolylineVS;
  exports._shadersRGBToHSB = czm_RGBToHSB;
  exports._shadersRGBToHSL = czm_RGBToHSL;
  exports._shadersRGBToXYZ = czm_RGBToXYZ;
  exports._shadersReinhardTonemapping = ReinhardTonemapping;
  exports._shadersReprojectWebMercatorFS = ReprojectWebMercatorFS;
  exports._shadersReprojectWebMercatorVS = ReprojectWebMercatorVS;
  exports._shadersRimLightingMaterial = RimLightingMaterial;
  exports._shadersShadowVolumeAppearanceFS = ShadowVolumeAppearanceFS;
  exports._shadersShadowVolumeAppearanceVS = ShadowVolumeAppearanceVS;
  exports._shadersShadowVolumeFS = ShadowVolumeFS;
  exports._shadersSilhouette = Silhouette;
  exports._shadersSkyAtmosphereCommon = SkyAtmosphereCommon;
  exports._shadersSkyAtmosphereFS = SkyAtmosphereFS;
  exports._shadersSkyAtmosphereVS = SkyAtmosphereVS;
  exports._shadersSkyBoxFS = SkyBoxFS;
  exports._shadersSkyBoxVS = SkyBoxVS;
  exports._shadersSlopeRampMaterial = SlopeRampMaterial;
  exports._shadersStripeMaterial = StripeMaterial;
  exports._shadersSunFS = SunFS;
  exports._shadersSunTextureFS = SunTextureFS;
  exports._shadersSunVS = SunVS;
  exports._shadersTexturedMaterialAppearanceFS = TexturedMaterialAppearanceFS;
  exports._shadersTexturedMaterialAppearanceVS = TexturedMaterialAppearanceVS;
  exports._shadersVector3DTilePolylinesVS = Vector3DTilePolylinesVS;
  exports._shadersVectorTileVS = VectorTileVS;
  exports._shadersViewportQuadFS = ViewportQuadFS;
  exports._shadersViewportQuadVS = ViewportQuadVS;
  exports._shadersWater = WaterMaterial;
  exports._shadersXYZToRGB = czm_XYZToRGB;
  exports._shadersacesTonemapping = czm_acesTonemapping;
  exports._shadersalphaWeight = czm_alphaWeight;
  exports._shadersantialias = czm_antialias;
  exports._shadersapproximateSphericalCoordinates = czm_approximateSphericalCoordinates;
  exports._shadersbackFacing = czm_backFacing;
  exports._shadersbranchFreeTernary = czm_branchFreeTernary;
  exports._shaderscascadeColor = czm_cascadeColor;
  exports._shaderscascadeDistance = czm_cascadeDistance;
  exports._shaderscascadeMatrix = czm_cascadeMatrix;
  exports._shaderscascadeWeights = czm_cascadeWeights;
  exports._shaderscolumbusViewMorph = czm_columbusViewMorph;
  exports._shaderscomputePosition = czm_computePosition;
  exports._shaderscosineAndSine = czm_cosineAndSine;
  exports._shadersdecompressTextureCoordinates = czm_decompressTextureCoordinates;
  exports._shadersdegreesPerRadian = czm_degreesPerRadian;
  exports._shadersdepthClamp = czm_depthClamp;
  exports._shadersdepthRange = czm_depthRange;
  exports._shadersdepthRangeStruct = czm_depthRangeStruct;
  exports._shaderseastNorthUpToEyeCoordinates = czm_eastNorthUpToEyeCoordinates;
  exports._shadersellipsoidContainsPoint = czm_ellipsoidContainsPoint;
  exports._shadersellipsoidWgs84TextureCoordinates = czm_ellipsoidWgs84TextureCoordinates;
  exports._shadersepsilon1 = czm_epsilon1;
  exports._shadersepsilon2 = czm_epsilon2;
  exports._shadersepsilon3 = czm_epsilon3;
  exports._shadersepsilon4 = czm_epsilon4;
  exports._shadersepsilon5 = czm_epsilon5;
  exports._shadersepsilon6 = czm_epsilon6;
  exports._shadersepsilon7 = czm_epsilon7;
  exports._shadersequalsEpsilon = czm_equalsEpsilon;
  exports._shaderseyeOffset = czm_eyeOffset;
  exports._shaderseyeToWindowCoordinates = czm_eyeToWindowCoordinates;
  exports._shadersfastApproximateAtan = czm_fastApproximateAtan;
  exports._shadersfog = czm_fog;
  exports._shadersgammaCorrect = czm_gammaCorrect;
  exports._shadersgeodeticSurfaceNormal = czm_geodeticSurfaceNormal;
  exports._shadersgetDefaultMaterial = czm_getDefaultMaterial;
  exports._shadersgetLambertDiffuse = czm_getLambertDiffuse;
  exports._shadersgetSpecular = czm_getSpecular;
  exports._shadersgetWaterNoise = czm_getWaterNoise;
  exports._shadershue = czm_hue;
  exports._shadersinfinity = czm_infinity;
  exports._shadersinverseGamma = czm_inverseGamma;
  exports._shadersisEmpty = czm_isEmpty;
  exports._shadersisFull = czm_isFull;
  exports._shaderslatitudeToWebMercatorFraction = czm_latitudeToWebMercatorFraction;
  exports._shaderslineDistance = czm_lineDistance;
  exports._shadersluminance = czm_luminance;
  exports._shadersmaterial = czm_material;
  exports._shadersmaterialInput = czm_materialInput;
  exports._shadersmetersPerPixel = czm_metersPerPixel;
  exports._shadersmodelToWindowCoordinates = czm_modelToWindowCoordinates;
  exports._shadersmultiplyWithColorBalance = czm_multiplyWithColorBalance;
  exports._shadersnearFarScalar = czm_nearFarScalar;
  exports._shadersoctDecode = czm_octDecode;
  exports._shadersoneOverPi = czm_oneOverPi;
  exports._shadersoneOverTwoPi = czm_oneOverTwoPi;
  exports._shaderspackDepth = czm_packDepth;
  exports._shaderspassCesium3DTile = czm_passCesium3DTile;
  exports._shaderspassCesium3DTileClassification = czm_passCesium3DTileClassification;
  exports._shaderspassCesium3DTileClassificationIgnoreShow = czm_passCesium3DTileClassificationIgnoreShow;
  exports._shaderspassClassification = czm_passClassification;
  exports._shaderspassCompute = czm_passCompute;
  exports._shaderspassEnvironment = czm_passEnvironment;
  exports._shaderspassGlobe = czm_passGlobe;
  exports._shaderspassOpaque = czm_passOpaque;
  exports._shaderspassOverlay = czm_passOverlay;
  exports._shaderspassTerrainClassification = czm_passTerrainClassification;
  exports._shaderspassTranslucent = czm_passTranslucent;
  exports._shadersphong = czm_phong;
  exports._shaderspi = czm_pi;
  exports._shaderspiOverFour = czm_piOverFour;
  exports._shaderspiOverSix = czm_piOverSix;
  exports._shaderspiOverThree = czm_piOverThree;
  exports._shaderspiOverTwo = czm_piOverTwo;
  exports._shadersplaneDistance = czm_planeDistance;
  exports._shaderspointAlongRay = czm_pointAlongRay;
  exports._shadersradiansPerDegree = czm_radiansPerDegree;
  exports._shadersray = czm_ray;
  exports._shadersrayEllipsoidIntersectionInterval = czm_rayEllipsoidIntersectionInterval;
  exports._shadersraySegment = czm_raySegment;
  exports._shadersreadDepth = czm_readDepth;
  exports._shadersreadNonPerspective = czm_readNonPerspective;
  exports._shadersreverseLogDepth = czm_reverseLogDepth;
  exports._shaderssampleOctahedralProjection = czm_sampleOctahedralProjection;
  exports._shaderssaturation = czm_saturation;
  exports._shaderssceneMode2D = czm_sceneMode2D;
  exports._shaderssceneMode3D = czm_sceneMode3D;
  exports._shaderssceneModeColumbusView = czm_sceneModeColumbusView;
  exports._shaderssceneModeMorphing = czm_sceneModeMorphing;
  exports._shadersshadowDepthCompare = czm_shadowDepthCompare;
  exports._shadersshadowParameters = czm_shadowParameters;
  exports._shadersshadowVisibility = czm_shadowVisibility;
  exports._shaderssignNotZero = czm_signNotZero;
  exports._shaderssolarRadius = czm_solarRadius;
  exports._shaderssphericalHarmonics = czm_sphericalHarmonics;
  exports._shaderstangentToEyeSpaceMatrix = czm_tangentToEyeSpaceMatrix;
  exports._shadersthreePiOver2 = czm_threePiOver2;
  exports._shaderstransformPlane = czm_transformPlane;
  exports._shaderstranslateRelativeToEye = czm_translateRelativeToEye;
  exports._shaderstranslucentPhong = czm_translucentPhong;
  exports._shaderstranspose = czm_transpose;
  exports._shaderstwoPi = czm_twoPi;
  exports._shadersunpackDepth = czm_unpackDepth;
  exports._shadersunpackFloat = czm_unpackFloat;
  exports._shadersvertexLogDepth = czm_vertexLogDepth;
  exports._shaderswebMercatorMaxLatitude = czm_webMercatorMaxLatitude;
  exports._shaderswindowToEyeCoordinates = czm_windowToEyeCoordinates;
  exports._shaderswriteDepthClamp = czm_writeDepthClamp;
  exports._shaderswriteLogDepth = czm_writeLogDepth;
  exports._shaderswriteNonPerspective = czm_writeNonPerspective;
  exports.addBuffer = addBuffer;
  exports.addDefaults = addDefaults;
  exports.addExtensionsRequired = addExtensionsRequired;
  exports.addExtensionsUsed = addExtensionsUsed;
  exports.addPipelineExtras = addPipelineExtras;
  exports.addToArray = addToArray;
  exports.appendForwardSlash = appendForwardSlash;
  exports.arrayFill = arrayFill;
  exports.arrayRemoveDuplicates = arrayRemoveDuplicates;
  exports.arraySlice = arraySlice;
  exports.barycentricCoordinates = barycentricCoordinates;
  exports.binarySearch = binarySearch;
  exports.bitmap_sdf = calcSDF;
  exports.buildModuleUrl = buildModuleUrl;
  exports.cancelAnimationFrame = cancelAnimationFramePolyfill;
  exports.clone = clone;
  exports.combine = combine;
  exports.computeFlyToLocationForRectangle = computeFlyToLocationForRectangle;
  exports.createBillboardPointCallback = createBillboardPointCallback;
  exports.createCommand = createCommand$2;
  exports.createDefaultImageryProviderViewModels = createDefaultImageryProviderViewModels;
  exports.createDefaultTerrainProviderViewModels = createDefaultTerrainProviderViewModels;
  exports.createGuid = createGuid;
  exports.createMaterialPropertyDescriptor = createMaterialPropertyDescriptor;
  exports.createOsmBuildings = createOsmBuildings;
  exports.createPropertyDescriptor = createPropertyDescriptor;
  exports.createRawPropertyDescriptor = createRawPropertyDescriptor;
  exports.createTangentSpaceDebugPrimitive = createTangentSpaceDebugPrimitive;
  exports.createTaskProcessorWorker = createTaskProcessorWorker;
  exports.createUniform = createUniform$1;
  exports.createUniformArray = createUniformArray;
  exports.createWorldImagery = createWorldImagery;
  exports.createWorldTerrain = createWorldTerrain;
  exports.decodeGoogleEarthEnterpriseData = decodeGoogleEarthEnterpriseData;
  exports.defaultValue = defaultValue;
  exports.defined = defined;
  exports.deprecationWarning = deprecationWarning;
  exports.destroyObject = destroyObject;
  exports.earcut_2_2_1 = earcut;
  exports.exportKml = exportKml;
  exports.findAccessorMinMax = findAccessorMinMax;
  exports.formatError = formatError;
  exports.freezeRenderState = freezeRenderState;
  exports.getAbsoluteUri = getAbsoluteUri;
  exports.getAccessorByteStride = getAccessorByteStride;
  exports.getBaseUri = getBaseUri;
  exports.getBinaryAccessor = getBinaryAccessor;
  exports.getClipAndStyleCode = getClipAndStyleCode;
  exports.getClippingFunction = getClippingFunction;
  exports.getComponentReader = getComponentReader;
  exports.getElement = getElement;
  exports.getExtensionFromUri = getExtensionFromUri;
  exports.getFilenameFromUri = getFilenameFromUri;
  exports.getImagePixels = getImagePixels;
  exports.getMagic = getMagic;
  exports.getStringFromTypedArray = getStringFromTypedArray;
  exports.getTimestamp = getTimestamp$1;
  exports.graphemesplitter = GraphemeSplitter;
  exports.hasExtension = hasExtension;
  exports.heightReferenceOnEntityPropertyChanged = heightReferenceOnEntityPropertyChanged;
  exports.isBitSet = isBitSet;
  exports.isBlobUri = isBlobUri;
  exports.isCrossOriginUrl = isCrossOriginUrl;
  exports.isDataUri = isDataUri;
  exports.isLeapYear = isLeapYear;
  exports.jsep = jsep;
  exports.kdbush = kdbush;
  exports.knockout = knockout;
  exports.knockout_3_5_1 = knockout;
  exports.knockout_es5 = knockout_es5;
  exports.loadAndExecuteScript = loadAndExecuteScript;
  exports.loadCRN = loadCRN;
  exports.loadCubeMap = loadCubeMap;
  exports.loadImageFromTypedArray = loadImageFromTypedArray;
  exports.loadKTX = loadKTX;
  exports.measureText = measureText;
  exports.mergeSort = mergeSort;
  exports.mersenne_twister = MersenneTwister;
  exports.modernizeShader = modernizeShader;
  exports.moveTechniqueRenderStates = moveTechniqueRenderStates;
  exports.moveTechniquesToExtension = moveTechniquesToExtension;
  exports.numberOfComponentsForType = numberOfComponentsForType;
  exports.objectToQuery = objectToQuery;
  exports.oneTimeWarning = oneTimeWarning;
  exports.parseGlb = parseGlb;
  exports.parseResponseHeaders = parseResponseHeaders;
  exports.pointInsideTriangle = pointInsideTriangle;
  exports.processModelMaterialsCommon = processModelMaterialsCommon;
  exports.processPbrMaterials = processPbrMaterials;
  exports.protobuf_minimal = protobuf;
  exports.purify = purify;
  exports.queryToObject = queryToObject;
  exports.quickselect = quickselect$1;
  exports.rbush = RBush;
  exports.readAccessorPacked = readAccessorPacked;
  exports.removeExtensionsRequired = removeExtensionsRequired;
  exports.removeExtensionsUsed = removeExtensionsUsed;
  exports.removePipelineExtras = removePipelineExtras;
  exports.removeUnusedElements = removeUnusedElements;
  exports.requestAnimationFrame = requestAnimationFramePolyFill;
  exports.sampleTerrain = sampleTerrain;
  exports.sampleTerrainMostDetailed = sampleTerrainMostDetailed;
  exports.scaleToGeodeticSurface = scaleToGeodeticSurface;
  exports.sprintf = sprintf;
  exports.subdivideArray = subdivideArray;
  exports.subscribeAndEvaluate = subscribeAndEvaluate;
  exports.topojson = topojson;
  exports.updateAccessorComponentTypes = updateAccessorComponentTypes;
  exports.updateVersion = updateVersion;
  exports.viewerCesium3DTilesInspectorMixin = viewerCesium3DTilesInspectorMixin;
  exports.viewerCesiumInspectorMixin = viewerCesiumInspectorMixin;
  exports.viewerDragDropMixin = viewerDragDropMixin;
  exports.viewerPerformanceWatchdogMixin = viewerPerformanceWatchdogMixin;
  exports.webGLConstantToGlslType = webGLConstantToGlslType;
  exports.when = when;
  exports.wrapFunction = wrapFunction;
  exports.writeTextToCanvas = writeTextToCanvas;
  exports.zip = zip;

  Object.defineProperty(exports, '__esModule', { value: true });

})));
//# sourceMappingURL=Cesium.js.map